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Sample records for absorbed gamma dose

  1. Computational determination of absorbed dose distributions from multiple volumetric gamma ray sources

    Science.gov (United States)

    Zhou, Chuanyu; Inanc, Feyzi

    2002-05-01

    Determination of absorbed dose distributions is very important in brachytherapy procedures. The typical computation involves superposition of absorbed dose distributions from a single seed to compute the combined absorbed dose distribution formed by multiple seeds. This approach does not account for the shadow effect caused by the metallic nature of volumetric radioactive seeds. Since this shadow effect will cause deviations from the targeted dose distribution, it may have important implications on the success of the procedures. We demonstrated accuracy of our deterministic algorithms for isotropic point sources in the past. We will show that we now have the capability of computing absorbed dose distributions from multiple volumetric seeds and demonstrate that our results are quite close to the results published in the literature.

  2. Determination of the absorbed dose rate to water for the 18-mm helmet of a gamma knife.

    Science.gov (United States)

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

    2011-04-01

    To measure the absorbed dose rate to water of (60)Co gamma rays of a Gamma Knife Model C using water-filled phantoms (WFP). Spherical WFP with an equivalent water depth of 5, 7, 8, and 9 cm were constructed. The dose rates at the center of an 18-mm helmet were measured in an 8-cm WFP (WFP-3) and two plastic phantoms. Two independent measurement systems were used: one was calibrated to an air kerma (Set I) and the other was calibrated to the absorbed dose to water (Set II). The dose rates of WFP-3 and the plastic phantoms were converted to dose rates for an 8-cm water depth using the attenuation coefficient and the equivalent water depths. The dose rate measured at the center of WFP-3 using Set II was 2.2% and 1.0% higher than dose rates measured at the center of the two plastic phantoms. The measured effective attenuation coefficient of Gamma Knife photon beam in WFPs was 0.0621 cm(-1). After attenuation correction, the difference between the dose rate at an 8-cm water depth measured in WFP-3 and dose rates in the plastic phantoms was smaller than the uncertainty of the measurements. Systematic errors related to the characteristics of the phantom materials in the dose rate measurement of a Gamma Knife need to be corrected for. Correction of the dose rate using an equivalent water depth and attenuation provided results that were more consistent. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. 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

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

    Science.gov (United States)

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

    2000-03-01

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

  5. 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

    2006-09-07

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

  6. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-15

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

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

    Directory of Open Access Journals (Sweden)

    Mohammad Mirzaie

    2012-09-01

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

  9. 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.

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

    Science.gov (United States)

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

    2014-03-01

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

  11. X-ray and gamma-ray absorbed dose profiles in teeth: An EPR and modeling study

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, S. [Scientific Center of Radiation Medicine, Melnikova Street, 53, Kiev (Ukraine)], E-mail: sholom@leed1.kiev.ua; O' Brien, M. [Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Bakhanova, E.; Chumak, V. [Scientific Center of Radiation Medicine, Melnikova Street, 53, Kiev (Ukraine); Desrosiers, M. [Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Bouville, A. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, DHHS, Bethesda, MD (United States)

    2007-07-15

    Dose profiles in teeth have been experimentally and theoretically studied for different energies and geometries of incident X- and gamma-rays. The experiments were conducted with teeth inside of an Alderson phantom using monodirectional radiation beams at selected energies; they revealed two effects: an apparent lack of dose attenuation between the buccal and the lingual sides of the teeth for energies higher than 120 keV and an attenuation between first and last tooth layers for low-energy beams in the range from 0.28 to 0.57. Monte Carlo simulations confirmed the experimental data and provided dose profiles for other energies and geometries. In particular, exposure in the rotational radiation field produces pronounced dose profiles only for energies lower than 60 keV. The usefulness of these data to estimate the average energy of accidental radiation field is discussed.

  12. Comparison of the standards for absorbed dose to water of the NMIJ and the BIPM for {sup 60}Co {gamma}-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C.; Allisy-Roberts, P.J. [Bureau International des Poids et Mesures, Pavillon de Breteuil, F-92312 Sevres cedex (France); Morishita, Y.; Kato, M.; Takata, N.; Kurosawa, T.; Tanaka, T.; Saito, N. [National Metrology Institute of Japan, AIST, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2011-06-15

    A comparison of the standards for absorbed dose to water of the National Metrology Institute of Japan (NMIJ) and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 60}Co {gamma}-ray reference beam of the BIPM in November to December 2009 under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result, based on the calibration coefficients for two transfer standards and expressed as a ratio of the NMIJ and the BIPM standards for absorbed dose to water, is 0.9960(46). The degrees of equivalence between the NMIJ 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 participated. A graphical presentation is also given. (authors)

  13. 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).

  14. 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.

  15. 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)

  16. [Absorbed doses in dental radiology].

    Science.gov (United States)

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

    1996-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-15

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

  18. 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)

  19. 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)

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

    Science.gov (United States)

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

    2016-12-01

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

  1. 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)

  2. 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)

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

    Science.gov (United States)

    Garcia, Tristan; Anton, Mathias; Sharpe, Peter

    2012-01-01

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

  4. Methods of calculating radiation absorbed dose.

    Science.gov (United States)

    Wegst, A V

    1987-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  7. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Esau Francisco Sena

    2006-07-01

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

  9. The changes in optical absorbance of ZrO{sub 2} thin film with the rise of the absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Abayli, D., E-mail: abayli@itu.edu.tr; Baydogan, N., E-mail: dogannil@itu.edu.tr [Energy Institute, Istanbul Technical University, Ayazaga Campus, 34469, Istanbul (Turkey)

    2016-03-25

    In this study, zirconium oxide (ZrO{sub 2}) thin film samples prepared by sol–gel method were irradiated using Co-60 radioisotope as gamma source. Then, it was investigated the ionizing effect on optical properties of ZrO{sub 2} thin film samples with the rise of the absorbed dose. The changes in the optical absorbance of ZrO{sub 2} thin films were determined by using optical transmittance and the reflectance measurements in the range between 190 – 1100 nm obtained from PG Instruments T80 UV-Vis spectrophotometer.

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

    DEFF Research Database (Denmark)

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

    1980-01-01

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

  11. Radiation absorbed dose measurement after I-131 metaiodobenzylguanidine treatment in a patient with pheochromycytoma

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Won Il; Kim, Byeung Il; Lee, Jae Sung; Lee, Jung Rim; Choi, Chang Woon; Lim, Sang Moo; Hong, Sung Woon [Korea Cancer Center, Seoul (Korea, Republic of)

    1999-08-01

    The measurement of radiation absorbed dose is useful to predict the response after I-131 labeled metaiodobenzylguanidine (MIBG) therapy and determine therapy dose in patients with unresectable or malignant pheochromocytoma. We estimated the absorbed dose in tumor tissue after high dose I-131 MIBG in a patient with pheochromocytoma using a gamma camera and Medical Internal Radiation Dose (MIRD) formula. A 64-year old female patient with pheochromocytoma who had multiple metastases of mediastinum, right kidney and periaortic lymph nodes, received 74 GBq (200 mCi) of K-131 MIBG. We obtained anterior and posterior images at 0.5, 16, 24, 64 and 145 hours after treatment. Two standard sources of 37 and 74 MBq of I-131 were imaged simulatanously. Cummulated I-131 MIBG uptake in tumor tissue was calculated after the correction of background activity, attenuation, system sensitivity and count loss at a high count rate. The calculated absorbed radiation dose was 32-63 Gy/ 74 GBq, which was lower than the known dose for tumor remission (150-200 Gy). Follow-up studies at 1 month showed minimally reduced tumor size on computed tomography, and mildly reduced I-131 MIBG uptake. We estimated radiation absorbed dose after therapeutic I-131 MIBG using a gamma camera and MIRD formula, which can be peformed in a clinical nuclear medicine laboratory. Our results suggest that the measurement of radiation absorbed dose in I-131 MIBG therapy is feasible as a routine clinical practice that can guide further treatment plan. The accuracy of dose measurement and correlation with clinical outcome should be evaluated further.

  12. Comparison of absorbed dose to air calibration factors for a parallel plate ionization chamber

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, Roseli T.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN), Sao Paulo, SP (Brazil)]. E-mail: lcaldas@ipen.br; rtbulla@ig.com.br

    2006-05-15

    Objective: the objective of this study was to compare the absorbed dose to air calibration factors determined in gamma ({sup 60}Co) and electron beams.Objective: an irradiator with a {sup 60}Co 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 {sup 60}Co beams, at maximum, are 1.2% higher than the values obtained in high energy electron beams. (author)

  13. 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)

  14. Measurement of absorbed dose and proposed radiation exposure level

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-03-01

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

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

    Science.gov (United States)

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

    2013-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in April 2013. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the LNE-LNHB and the BIPM standards for absorbed dose to water, is 0.9971 with a combined standard uncertainty of 3.9 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. 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...

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

    Science.gov (United States)

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

    2005-09-01

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

  18. The dose of gamma radiation from building materials and soil

    Directory of Open Access Journals (Sweden)

    Manić Goran

    2015-12-01

    Full Text Available The radioactivity of some structural building materials, rows, binders, and final construction products, originating from Serbia or imported from other countries, was investigated in the current study by using the standard HPGe gamma spectrometry. The absorbed dose in the air was computed by the method of buildup factors for models of the room with the walls of concrete, gas-concrete, brick and stone. Using the conversion coefficients obtained by interpolation of the International Commission on Radiobiological Protection (ICRP equivalent doses for isotropic irradiation, the corresponding average indoor effective dose from the radiation of building materials of 0.24 mSv·y−1 was determined. The outdoor dose of 0.047 mSv·y−1 was estimated on the basis of values of the specific absorbed dose rates calculated for the radiation of the series of 238U, 232Th and 40K from the ground and covering materials. The literature values of the effective dose conversion coefficients for ground geometry were applied as well as the published data for content of the radionuclides in the soil.

  19. 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...

  20. Ceramic Matrix Composites Performances Under High Gamma Radiation Doses

    Science.gov (United States)

    Cemmi, A.; Baccaro, S.; Fiore, S.; Gislon, P.; Serra, E.; Fassina, S.; Ferrari, E.; Ghisolfi, E.

    2014-06-01

    Ceramic matrix composites reinforced by continuous ceramic fibers (CMCs) represent a class of advanced materials developed for applications in automotive, aerospace, nuclear fusion reactors and in other specific systems for harsh environments. In the present work, the silicon carbide/silicon carbide (SiCf/SiC) composites, manufactured by Chemical Vapour Infiltration process at FN S.p.A. plant, have been evaluated in term of gamma radiation hardness at three different absorbed doses (up to around 3MGy). Samples behavior has been investigated before and after irradiation by means of mechanical tests (flexural strength) and by surface and structural analyses (X-ray diffraction, SEM, FTIR-ATR, EPR).

  1. 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.

  2. 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)

  3. 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

  4. Electron paramagnetic resonance measurements of absorbed dose in teeth from citizens of Ozyorsk

    Energy Technology Data Exchange (ETDEWEB)

    Wieser, A.; Semiochkina, N. [Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Institute of Radiation Protection, Neuherberg (Germany); Vasilenko, E.; Aladova, E.; Smetanin, M. [Southern Urals Biophysics Institute, Ozyorsk (Russian Federation); Fattibene, P. [Istituto Superiore di Sanita, Rome (Italy)

    2014-05-15

    In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960. (orig.)

  5. Some comments on the concept of absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-15

    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 d{epsilon} divided by dm, where d{epsilon} 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 {epsilon}. 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)

  6. 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.

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

    Science.gov (United States)

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

    2002-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-01

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

  9. Isodose distributions and dose uniformity in the Portuguese gamma irradiation facility calculated using the MCNP code

    CERN Document Server

    Oliveira, C

    2001-01-01

    A systematic study of isodose distributions and dose uniformity in sample carriers of the Portuguese Gamma Irradiation Facility was carried out using the MCNP code. The absorbed dose rate, gamma flux per energy interval and average gamma energy were calculated. For comparison purposes, boxes filled with air and 'dummy' boxes loaded with layers of folded and crumpled newspapers to achieve a given value of density were used. The magnitude of various contributions to the total photon spectra, including source-dependent factors, irradiator structures, sample material and other origins were also calculated.

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

    Science.gov (United States)

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

    1994-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-12-01

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

  12. Absorbed Dose and Collision Kerma Relationship for High-Energy Photons

    Science.gov (United States)

    Sibata, Claudio Hissao

    Historically, exposure has been used as an important quantity to specify X- or (gamma)- ray beams. For any photon beam the energy fluence is proportional to the exposure. Exposure can be calculated and/or measured if the spectrum of the beam is known and charged particle equilibrium (CPE) exists. For low energy photons (up to approximately 1 MeV), due to the existence of CPE, absorbed dose (D) is equal to the collision kerma (K(,c)). For megavoltage photons this equality is lost due to CPE failure, which also restricts the measurement of exposure. It is possible, though, to find a relationship between the absorbed dose and collision kerma when transient charged particle equilibrium (TCPE) exists. This basic idea was originally proposed by Roesch in 1958 and its refinement has been discussed by Attix in 1979 and 1983. The modified Roesch's formula which enables us to measure exposure even for high-energy photons is given by D = (beta) K(,c) (TURNEQ) K(,c) (1 + (mu)' ) where (mu)' is the effective linear attenuation coefficient and is the mean distance the secondary electrons carry kinetic energy in the direction of the photon beam while depositing it as absorbed dose. The symbol (beta) is the quotient of the absorbed dose and the collision kerma. The importance of Roesch's formula has been recognized and used implicitly in the recent dosimetry protocol of the AAPM (Task Group 21). However, the value used in the protocol is based on theoretical calculations which do not include photon scattering. As a result of the present effort the parameters (mu)' and have been determined experimentally, for the first time. The dependence of (beta) on several factors has been studied and (beta) has been obtained including the effects of scattering. Calculations were also performed for several photon energies and materials, using the Roesch method, which does not include photon scattering effects. Comparisons of measured and calculated values of show reasonable agreement.

  13. 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.

  14. Correlation analysis of gamma dose rate from natural radiation in the test field

    Directory of Open Access Journals (Sweden)

    Avdic Senada

    2016-01-01

    Full Text Available This paper deals with correlation analysis of gamma dose rate measured in the test field with the five distinctive soil samples from a few minefields in Federation of Bosnia and Herzegovina. The measurements of ambient dose equivalent rate, due to radionuclides present in each of the soil samples, were performed by the RADIAGEMTM 2000 portable survey meter, placed on the ground and 1m above the ground. The gamma spectrometric analysis of the same soil samples was carried out by GAMMA-RAD5 spectrometer. This study showed that there is a high correlation between the absorbed dose rate evaluated from soil radioactivity and the corresponding results obtained by the survey meter placed on the ground. Correlation analysis indicated that the survey meter, due to its narrow energy range, is not suitable for the examination of cosmic radiation contribution.

  15. Abdominal pediatric cancer surveillance using serial computed tomography: evaluation of organ absorbed dose and effective dose.

    Science.gov (United States)

    Lam, Diana; Wootton-Gorges, Sandra L; McGahan, John P; Stern, Robin; Boone, John M

    2011-02-01

    Computed tomography (CT) is used extensively in cancer diagnosis, staging, evaluation of response to treatment, and in active surveillance for cancer reoccurrence. A review of CT technology is provided, at a level of detail appropriate for a busy clinician to review. The basis of x-ray CT dosimetry is also discussed, and concepts of absorbed dose and effective dose (ED) are distinguished. Absorbed dose is a physical quantity (measured in milligray [mGy]) equal to the x-ray energy deposited in a mass of tissue, whereas ED uses an organ-specific weighting method that converts organ doses to ED measured in millisieverts (mSv). The organ weighting values carry with them a measure of radiation risk, and so ED (in mSv) is not a physical dose metric but rather is one that conveys radiation risk. The use of CT in a cancer surveillance protocol was used as an example of a pediatric patient who had kidney cancer, with surgery and radiation therapy. The active use of CT for cancer surveillance along with diagnostic CT scans led to a total of 50 CT scans performed on this child in a 7-year period. It was estimated that the patient received an average organ dose of 431 mGy from these CT scans. By comparison, the radiation therapy was performed and delivered 50.4 Gy to the patient's abdomen. Thus, the total dose from CT represented only 0.8% of the patient's radiation dose. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Gamma ray attenuation coefficient measurement for neutron-absorbent materials

    Energy Technology Data Exchange (ETDEWEB)

    Jalali, Majid [Isfahan Nuclear Science and Technology Research Institute (NSTRT), Reactor and Accelerators Research and Development School, Atomic Energy Organization (Iran, Islamic Republic of)], E-mail: m_jalali@entc.org.ir; Mohammadi, Ali [Faculty of Science, Department of Physics, University of Kashan, Km. 6, Ravand Road, Kashan (Iran, Islamic Republic of)

    2008-05-15

    The compounds Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the {gamma} rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H{sub 3}BO{sub 3} with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds.

  17. 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 ...

  18. Amorphous and crystalline optical materials used as instruments for high gamma radiation doses estimations

    Energy Technology Data Exchange (ETDEWEB)

    Ioan, M-R., E-mail: razvan.ioan@nipne.ro

    2016-06-15

    Highlights: • The damage induced by gamma rays to optical materials was highlighted and quantified, using laser techniques. • Polarized light and the particularities of the laser light (monochromaticity, directionality and coherence) were used. • The correlation between the damage and the gamma rays absorbed dose was made. • The comparison between different types of optical materials and their dose related calibrations were made. • The uncertainty associated to the technique was determined. - Abstract: Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiation dose can be done. By using two types of laser wavelengths (532 nm and 633 nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1 kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

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

    Science.gov (United States)

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

    2015-11-01

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

  20. Aspartame tablets-gamma dose response and usability for routine radiation processing dosimetry using spectrophotometry

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, S.H. [Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)]. E-mail: shs_barc@yahoo.com; Mukherjee, T. [Radiation Safety Systems Division, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2007-02-15

    Aspartame tablets were studied for gamma dose response, using spectrophotometric read-out method. The optimum concentration for ferrous ions was 2x10{sup -4}moldm{sup -3} and xylenol orange with 2.5x10{sup -1}moldm{sup -3} of sulphuric acid for the optimum acidity in FX solution. Wavelength of maximum absorbance is 548nm. Post-irradiation stability is appreciable i.e. for not less than one month. Dose response is non-linear with third order polynomial fit, in the dose range of 1000-10000Gy. This system of aspartame was further used for carrying out relative percentage dose profile measurement in Gamma Cell-220. Results obtained were inter-compared with that of a glutamine dosimeter, which showed that maximum difference between the values of aspartame and glutamine systems is within +/-10%.

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

    Science.gov (United States)

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

    2016-12-01

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

  2. 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.

  3. Terrestrial gamma dose rates and physical-chemical properties of ...

    African Journals Online (AJOL)

    Terrestrial gamma dose rates and physical-chemical properties of farm soils ... African Journal of Environmental Science and Technology ... left a legacy derelict landscapes and impoverished agricultural farm lands in the Jos, Plateau Nigeria.

  4. Physical changes associated with gamma doses on Wood/ Polypropylene Composites

    Science.gov (United States)

    Ndiaye, Diène; Tidjani, Adams

    2014-08-01

    The effect of gamma- radiation on the morphology, thermal behavior and mechanical properties of wood polypropylene composites has been investigated. Simultaneous thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been performed on WPC samples of (9.5 ± 0.1) mg. These samples were exposed to different gamma-dose in the range 10 to 100kGy. The results indicated that gamma radiation improves the mechanical properties while the thermal stability is decreased. With gamma radiation, the scanning electron microscopy (SEM) of the micrographs became smoother and we can notice an improvement of interaction between polymer and wood fibers.

  5. Dose-Response Curve of Chromosome Aberrations in Human Lymphocytes Induced by Gamma-Rays

    Directory of Open Access Journals (Sweden)

    Y. Lusiyanti

    2013-12-01

    Full Text Available Chromosome aberration is a biomarker to predict the level of cell damage caused by exposure to ionizing radiation on human body. Dicentric chromosome is a specific chromosome aberration caused by ionizing radiation and is used as a gold standard biodosimetry of individuals over exposed to ionizing radiation. In radiation accident the dicentric assays has been applied as biological dosimetry to estimate radiation absorbed dose and also to confirm the radiation dose received to radiation workers.The purpose of this study was to generate a dose response curve of chromosome aberration (dicentric in human lymphocyte induced by gamma radiation. Peripheral blood samples from three non smoking healthy volunteers aged between 25-48 years old with informed consent were irradiated with dose between 0.1-4.0 Gy and a control using gamma teletherapy source. The culture procedure was conducted following the IAEA standard procedures with slight modifications. Analysis of dose-response curves used was LQ model Y = a + αD + βD2. The result showed that α and β values of the curve obtained were 0.018 ± 0.006 and 0.013 ± 0.002, respectively. Dose response calibration curve for dicentric chromosome aberrations in human lymphocytes induced by gamma-radiation fitted to linear quadratic model. In order to apply the dose response curve of chromosome aberration disentric for biodosimetry, this standar curve still need to be validated.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-06-15

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

  7. 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

  8. 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...

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

    Science.gov (United States)

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

    1982-05-01

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

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

    Science.gov (United States)

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

    2014-05-01

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

  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. 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...

  13. Spectroscopic gamma camera for use in high dose environments

    Science.gov (United States)

    Ueno, Yuichiro; Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi; Fujishima, Yasutake; Kometani, Yutaka; Suzuki, Yasuhiko; Umegaki, Kikuo

    2016-06-01

    We developed a pinhole gamma camera to measure distributions of radioactive material contaminants and to identify radionuclides in extraordinarily high dose regions (1000 mSv/h). The developed gamma camera is characterized by: (1) tolerance for high dose rate environments; (2) high spatial and spectral resolution for identifying unknown contaminating sources; and (3) good usability for being carried on a robot and remotely controlled. These are achieved by using a compact pixelated detector module with CdTe semiconductors, efficient shielding, and a fine resolution pinhole collimator. The gamma camera weighs less than 100 kg, and its field of view is an 8 m square in the case of a distance of 10 m and its image is divided into 256 (16×16) pixels. From the laboratory test, we found the energy resolution at the 662 keV photopeak was 2.3% FWHM, which is enough to identify the radionuclides. We found that the count rate per background dose rate was 220 cps h/mSv and the maximum count rate was 300 kcps, so the maximum dose rate of the environment where the gamma camera can be operated was calculated as 1400 mSv/h. We investigated the reactor building of Unit 1 at the Fukushima Dai-ichi Nuclear Power Plant using the gamma camera and could identify the unknown contaminating source in the dose rate environment that was as high as 659 mSv/h.

  14. Spectroscopic gamma camera for use in high dose environments

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Yuichiro, E-mail: yuichiro.ueno.bv@hitachi.com [Research and Development Group, Hitachi, Ltd., Hitachi-shi, Ibaraki-ken 319-1221 (Japan); Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi [Research and Development Group, Hitachi, Ltd., Hitachi-shi, Ibaraki-ken 319-1221 (Japan); Fujishima, Yasutake; Kometani, Yutaka [Hitachi Works, Hitachi-GE Nuclear Energy, Ltd., Hitachi-shi, Ibaraki-ken (Japan); Suzuki, Yasuhiko [Measuring Systems Engineering Dept., Hitachi Aloka Medical, Ltd., Ome-shi, Tokyo (Japan); Umegaki, Kikuo [Faculty of Engineering, Hokkaido University, Sapporo-shi, Hokkaido (Japan)

    2016-06-21

    We developed a pinhole gamma camera to measure distributions of radioactive material contaminants and to identify radionuclides in extraordinarily high dose regions (1000 mSv/h). The developed gamma camera is characterized by: (1) tolerance for high dose rate environments; (2) high spatial and spectral resolution for identifying unknown contaminating sources; and (3) good usability for being carried on a robot and remotely controlled. These are achieved by using a compact pixelated detector module with CdTe semiconductors, efficient shielding, and a fine resolution pinhole collimator. The gamma camera weighs less than 100 kg, and its field of view is an 8 m square in the case of a distance of 10 m and its image is divided into 256 (16×16) pixels. From the laboratory test, we found the energy resolution at the 662 keV photopeak was 2.3% FWHM, which is enough to identify the radionuclides. We found that the count rate per background dose rate was 220 cps h/mSv and the maximum count rate was 300 kcps, so the maximum dose rate of the environment where the gamma camera can be operated was calculated as 1400 mSv/h. We investigated the reactor building of Unit 1 at the Fukushima Dai-ichi Nuclear Power Plant using the gamma camera and could identify the unknown contaminating source in the dose rate environment that was as high as 659 mSv/h.

  15. 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...

  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. Radon survey and soil gamma doses in primary schools of Batman, Turkey.

    Science.gov (United States)

    Damla, Nevzat; Aldemir, Kamuran

    2014-06-01

    A survey was conducted to evaluate levels of indoor radon and gamma doses in 42 primary schools located in Batman, southeastern Anatolia, Turkey. Indoor radon measurements were carried out using CR-39 solid-state nuclear track detector-based radon dosimeters. The overall mean annual (222)Rn activity in the surveyed area was found to be 49 Bq m(-3) (equivalent to an annual effective dose of 0.25 mSv). However, in one of the districts (Besiri) the maximum radon value turned out to be 307 Bq m(-3). The estimated annual effective doses are less than the recommended action level (3-10 mSv). It is found that the radon concentration decreases with increasing floor number. The concentrations of natural and artificial radioisotopes were determined using gamma-ray spectroscopy for soil samples collected in close vicinity of the studied schools. The mean gamma activity concentrations in the soil samples were 31, 25, 329 and 12 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, respectively. The radiological parameters such as the absorbed dose rate in air and the annual effective dose equivalent were calculated. These radiological parameters were evaluated and compared with the internationally recommended values.

  18. 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

  19. Absorbed dose measurements in the build-up region of flattened versus unflattened megavoltage photon beams.

    Science.gov (United States)

    De Puysseleyr, Annemieke; Lechner, Wolfgang; De Neve, Wilfried; Georg, Dietmar; De Wagter, Carlos

    2016-06-01

    This study evaluated absorbed dose measurements in the build-up region of conventional (FF) versus flattening filter-free (FFF) photon beams. The absorbed dose in the build-up region of static 6 and 10MV FF and FFF beams was measured using radiochromic film and extrapolation chamber dosimetry for single beams with a variety of field sizes, shapes and positions relative to the central axis. Removing the flattening filter generally resulted in slightly higher relative build-up doses. No considerable impact on the depth of maximum dose was found. Copyright © 2016. Published by Elsevier GmbH.

  20. 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

    of the polyhalostyrenes have essentially rate-independent and moderately temperature-dependent responses to such large doses of ionizing radiation. While radiation-induced optical absorption in the ultraviolet for polystyrene is unstable following irradiation, thus leading to an intrinsic low-intensity rate dependence......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...

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

    Science.gov (United States)

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

    2017-01-01

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

  2. Natural radioactivity in some building materials in Cuba and their contribution to the indoor gamma dose rate

    Energy Technology Data Exchange (ETDEWEB)

    Brigido Flores, Osvaldo; Barreras Caballero, Aldo A.; Montalvan Estrada, Alberto; Queipo Garcia, Maite [Ministerio de Ciencia, Tecnologia y Medio Ambiente, Camaguey (Cuba). Centro de Atencion a la Actividad Nuclear. Lab. de Vigilancia Radiologica Ambiental]. E-mail: sean@caonao.cmw.inf.cu; Zerquera, Juan Tomas [Ministerio de Ciencia, Tecnologia y Medio Ambiente, La Habana (Cuba). Agencia de Energia Nuclear. Centro de Proteccion y Higiene de las Radiaciones

    2001-07-01

    The natural radioactivity of some building materials commonly used in Cuba was measured by gamma spectrometry. Typical concentrations, so far encountered, are in the ranges: 47 to 2511 Bq.kg{sup -1} for {sup 40} K; 9 to 71 Bq.kg{sup -1} for {sup 226} Ra; and 2 to 38 Bq.kg{sup -1} for {sup 232} Th. The external gamma ray absorbed doses in indoor air, and the corresponding effective dose equivalents in a typical dwelling are presented in this work. (author)

  3. Target and peripheral dose during patient repositioning with the Gamma Knife automatic positioning system (APS) device.

    Science.gov (United States)

    Tran, Tuan-Anh; Stanley, Thomas R; Malhotra, Harish K; De Boer, Steven F; Prasad, Dheerendra; Podgorsak, Matthew B

    2010-01-28

    The GammaPlan treatment planning system does not account for the leakage and scatter dose during APS repositioning. In this study, the dose delivered to the target site and its periphery from the defocus stage and intershot couch transit (couch motion from the focus to defocus position and back) associated with APS repositioning are measured for the Gamma Knife model 4C. A stereotactic head-frame was attached to a Leksell 16 cm diameter spherical phantom with a calibrated ion chamber at its center. Using a fiducial box, CT images of the phantom were acquired and registered in the GammaPlan treatment planning system to determine the coordinates of the target (center of the phantom). An absorbed dose of 10 Gy to the 50% isodose line was prescribed to the target site for all measurements. Plans were generated for the 8, 14 and 18 mm collimator helmets to determine the relationship of measured dose to the number of repositions of the APS system and to the helmet size. The target coordinate was identical throughout entire study and there was no movement of the APS between various shots. This allowed for measurement of intershot transit dose at the target site and its periphery. The couch was paused in the defocus position, allowing defocus dose measurements at the intracranial target and periphery. Measured dose increases with frequency of repositioning and with helmet collimator size. During couch transit, the target receives more dose than peripheral regions; however, in the defocus position, the greatest dose is superior to the target site. The automatic positioning system for the Leksell Gamma Knife model 4C results in an additional dose of up to 3.87 +/- 0.07%, 4.97 +/- 0.04%, and 5.71 +/- 0.07% to the target site; its periphery receives additional dose that varies depending on its position relative to the target. There is also dose contribution to the patient in the defocus position, where the APS repositions the patient from one treatment coordinate to another

  4. In vitro cell culture lethal dose submitted to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Carolina S.; Rogero, Sizue O.; Rogero, Jose Roberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: carolina_sm@hotmail.com; Ikeda, Tamiko I.; Cruz, Aurea S. [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil)

    2009-07-01

    The present study was designed to evaluate the in vitro effect of gamma radiation in cell culture of mouse connective tissue exposed to different doses of gamma radiation and under several conditions. The cell viability was analyzed by neutral red uptake methodology. This assay was developed for establish a methodology to be used in the future in the study of resveratrol radioprotection. Resveratrol (3,4',5- trihydroxystilbene), a phenolic phytoalexin that occurs naturally in some spermatophytes, such as grapevines, in response to injury as fungal infections and exposure to ultraviolet light. In the wines this compound is found at high levels and is considered one of the highest antioxidant constituents. The intense antioxidant potential of resveratrol provides many pharmacological activities including cardioprotection, chemoprevention and anti-tumor effects. Our results demonstrated that {sup 60}Co gamma radiation lethal dose (LD50) on NCTC clone 929 cells was about 340Gy. (author)

  5. Water absorbency studies of {gamma}-radiation crosslinked poly(acrylamide-co-2,3-dihydroxybutanedioic acid) hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Karadag, Erdener E-mail: ekaradag@adu.edu.tr; Saraydin, Dursun; Gueven, Olgun

    2004-10-01

    Water absorbency behavior of acrylamide (AAm)/2,3-dihydroxybutanedioic acid (DBA) hydrogels synthesized by {gamma}-radiation crosslinking of AAm and DBA in an aqueous solution was investigated. Different amounts of DBA containing AAm/DBA hydrogels were obtained in the form of rods via a radiation technique. Swelling experiments were performed in water at 25 deg. C, gravimetrically. The influence of absorbed dose and DBA content of the hydrogels on swelling properties were examined. The hydrogels showed enormous swelling in an aqueous medium and displayed swelling characteristics which were highly dependent on the chemical composition of the hydrogels and irradiation dose. Diffusion behavior and some swelling kinetic parameters were investigated. The values of the weight swelling ratio of AAm/DBA hydrogels were between 8.34 and 15.16, while the values of the weight swelling ratio of pure AAm hydrogels were between 7.58 and 8.28. Water diffusion into hydrogels was found to be non-Fickian in character. Equilibrium water contents of the hydrogel systems were changed between 0.8681 and 0.9340.

  6. Effect of low-Z absorber's thickness on gamma-ray shielding parameters

    Science.gov (United States)

    Mann, Kulwinder Singh; Heer, Manmohan Singh; Rani, Asha

    2015-10-01

    Gamma ray shielding behaviour of any material can be studied by various interaction parameters such as total mass attenuation coefficient (μm); half value layer (HVL); tenth value layer (TVL); effective atomic number (Zeff), electron density (Nel), effective atomic weight (Aeff) and buildup factor. For gamma rays, the accurate measurements of μm (cm2 g-1) theoretically require perfect narrow beam irradiation geometry. However, the practical geometries used for the experimental investigations deviate from perfect-narrowness thereby the multiple scattered photons cause systematic errors in the measured values of μm. Present investigation is an attempt to find the optimum value of absorber thickness (low-Z) for which these errors are insignificant and acceptable. Both experimental and theoretical calculations have been performed to investigate the effect of absorber's thickness on μm of six low-Z (10materials (cement-black; cement-white; clay; red-mud; lime-stone and plaster of paris) at gamma-ray energies 661.66 keV, 1173.24 keV and 1332.50 keV. A computer program (GRIC2-toolkit) was designed for theoretical evaluation of shielding parameters of any material. Good agreement of theoretical and measured values of μm was observed for all absorbers with thickness ≤0.5 mean free paths, thus considered it as optimum thickness for low-Z materials in the selected energy range. White cement was found to possess maximum shielding effectiveness for the selected gamma rays.

  7. Two Dimensional Verification of the Dose Distribution of Gamma Knife Model C using Monte Carlo Simulation with a Virtual Source

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Hoon; Kim, Yong-Kyun; Lee, Cheol Ho; Son, Jaebum; Lee, Sangmin; Kim, Dong Geon; Choi, Joonbum; Jang, Jae Yeong [Hanyang University, Seoul (Korea, Republic of); Chung, Hyun-Tai [Seoul National University, Seoul (Korea, Republic of)

    2016-10-15

    Gamma Knife model C contains 201 {sup 60}Co sources located on a spherical surface, so that each beam is concentrated on the center of the sphere. In the last work, we simulated the Gamma Knife model C through Monte Carlo simulation code using Geant4. Instead of 201 multi-collimation system, we made one single collimation system that collects source parameter passing through the collimator helmet. Using the virtual source, we drastically reduced the simulation time to transport 201 gamma circle beams to the target. Gamma index has been widely used to compare two dose distributions in cancer radiotherapy. Gamma index pass rates were compared in two calculated results using the virtual source method and the original method and measured results obtained using radiocrhomic films. A virtual source method significantly reduces simulation time of a Gamma Knife Model C and provides equivalent absorbed dose distributions as that of the original method showing Gamma Index pass rate close to 100% under 1mm/3% criteria. On the other hand, it gives a little narrow dose distribution compared to the film measurement showing Gamma Index pass rate of 94%. More accurate and sophisticated examination on the accuracy of the simulation and film measurement is necessary.

  8. 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.

  9. Gamma irradiator dose mapping: a Monte Carlo simulation and experimental measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Rogerio R.; Ribeiro, Mariana A.; Grynberg, Suely E.; Ferreira, Andrea V.; Meira-Belo, Luiz Claudio, E-mail: rrr@cdtn.b, E-mail: marianaalmeida@ufmg.b, E-mail: seg@cdtn.b, E-mail: avf@cdtn.b, E-mail: lcmb@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Sousa, Romulo V.; Sebastiao, Rita de C.O., E-mail: romuloverdolin@yahoo.com.b, E-mail: ritacos@ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Quimica

    2009-07-01

    Gamma irradiator facilities can be used in a wide range of applications such as biological and chemical researches, food treatment and sterilization of medical devices and products. Dose mapping must be performed in these equipment in order to establish plant operational parameters, as dose uniformity, source utilization efficiency and maximum and minimum dose positions. The isodoses curves are generally measured using dosimeters distributed throughout the device, and this procedure often consume a large amount of dosimeters, irradiation time and manpower. However, a detailed curve doses identification of the irradiation facility can be performed using Monte Carlo simulation, which reduces significantly the monitoring with dosimeters. The present work evaluates the absorbed dose in the CDTN/CNEN Gammacell Irradiation Facility, using the Monte Carlo N-particles (MCNP) code. The Gammacell 220, serial number 39, was produced by Atomic Energy of Canada Limited and was loaded with sources of {sup 60}Co. Dose measurements using TLD and Fricke dosimeters were also performed to validate the calculations. The good agreement of the results shows that Monte Carlo simulations can be used as a predictive tool of irradiation planning for the CDTN/CNEN Gamma Cell Irradiator. (author)

  10. Biological dose estimation for accidental supra-high dose gamma-ray exposure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y., E-mail: yingchen29@yahoo.com.cn [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China); Yan, X.K. [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China); Department of Radiation Safety, Beijing Institute of Nuclear and Chemical Safety, 14 Guan-cun, Dongcheng District, Beijing 100077 (China); Du, J.; Wang, Z.D.; Zhang, X.Q.; Zeng, F.G.; Zhou, P.K. [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China)

    2011-09-15

    To correctly estimate the biological dose of victims accidentally exposed to a very high dose of {sup 60}Co gamma-ray, a new dose-effect curve of chromosomal dicentrics/multicentrics and rings in the supra-high dose range was established. Peripheral blood from two healthy men was irradiated in vitro with doses of {sup 60}Co gamma-rays ranging from 6 to 22 Gy at a dose rate of 2.0 Gy/min. Lymphocytes were concentrated, cultured and harvested at 52 h, 68 h and 72 h. The numbers of dic + r were counted. The dose-effect curves were established and validated using comparisons with doses from the Tokai-mura accident and were then applied to two victims of supra-high dose exposure accident. The results indicated that there were no significant differences in chromosome aberration frequency among the different culture times from 52 h to 72 h. The 6-22 Gy dose-effect curve was fitted to a linear quadratic model Y = -2.269 + 0.776D - 7.868 x l0{sup -3}D{sup 2}. Using this mathematic model, the dose estimates were similar to data from Tokai-mura which were estimated by PCC ring. Whole body average doses of 9.7 Gy and 18.1 Gy for two victims in the Jining accident were satisfactorily given. We established and successfully applied a new dose-effect curve of chromosomal dicentrics plus ring (dic + r) after 6-22 Gy {gamma}-irradiation from a supra-high dose {sup 60}Co gamma-ray accident.

  11. 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.

  12. Comparison of the Absorbed Dose of Target Organs between Conventional and Digital Panoramic Radiography

    Directory of Open Access Journals (Sweden)

    Zohre Reyhani

    2016-09-01

    Full Text Available The purpose of this study was to measure and compare target organ’s exposure by direct digital and conventional panoramic radiography. Dose measurements were carried out on a RANDO phantom, which TLDs were placed into 5 target area: thyroid gland, left and right submandibular and parotid salivary glands. Panoramic radiographs were taken with two conventional (CRANEX Tome, Soredex, Tusula Finland and direct digital devices (CRANEX D, Soredex, Tusula Finland.In total, the phantom was irradiated 30 times in the two systems. The TLDs were then coded and analyzed. T-test of statistical analysis was used to find the correlation. We found statistically significant reduction in absorbed dose of target organs in digital panoramic radiography(P<0.01. The highest absorbed dose was for submandibular gland and the lowest was for thyroid gland. We concluded that can reduce absorbed dose in vital organs.

  13. Effect of low-Z absorber's thickness on gamma-ray shielding parameters

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Kulwinder Singh, E-mail: ksmann6268@gmail.com [Department of Applied Sciences, Punjab Technical University, Kapurthala 144601 (India); Department of Physics, D.A.V. College, Bathinda 151001, Punjab (India); Heer, Manmohan Singh [Department of Physics, Kanya Maha Vidyalaya, Jalandhar 144001 (India); Rani, Asha [Department of Applied Sciences, Ferozpur College of Engineering and Technology, Ferozshah, Ferozpur 142052 (India)

    2015-10-11

    Gamma ray shielding behaviour of any material can be studied by various interaction parameters such as total mass attenuation coefficient (μ{sub m}); half value layer (HVL); tenth value layer (TVL); effective atomic number (Z{sub eff}), electron density (N{sub el}), effective atomic weight (A{sub eff}) and buildup factor. For gamma rays, the accurate measurements of μ{sub m} (cm{sup 2} g{sup −1}) theoretically require perfect narrow beam irradiation geometry. However, the practical geometries used for the experimental investigations deviate from perfect-narrowness thereby the multiple scattered photons cause systematic errors in the measured values of μ{sub m}. Present investigation is an attempt to find the optimum value of absorber thickness (low-Z) for which these errors are insignificant and acceptable. Both experimental and theoretical calculations have been performed to investigate the effect of absorber's thickness on μ{sub m} of six low-Z (10gamma-ray energies 661.66 keV, 1173.24 keV and 1332.50 keV. A computer program (GRIC2-toolkit) was designed for theoretical evaluation of shielding parameters of any material. Good agreement of theoretical and measured values of μ{sub m} was observed for all absorbers with thickness ≤0.5 mean free paths, thus considered it as optimum thickness for low-Z materials in the selected energy range. White cement was found to possess maximum shielding effectiveness for the selected gamma rays. - Highlights: • Optimum thickness value is 0.5 mfp for low-Z absorbers in energy range 662–1332 keV. • For accurate measurement of μ{sub m} absorber's thickness should be ≤optimum thickness. • GRIC2-toolkit is useful for γ-ray shielding analysis of composite materials.

  14. 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.

  15. 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)

  16. Distribution of Absorbed Doses to the Important Organs of Head and Neck Region in Panoramic Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byeong Sam; Choi, Karp Sick [Dept. of Dental Radiology, College of Dentistry, Kyungpook National University, Deagu (Korea, Republic of); Kim, Chin Soo [Dept. of Oral and Maxillofacial Surgery, College of Dentistry, Kyungpook National University, Deagu (Korea, Republic of)

    1990-08-15

    The purpose of this study was to estimate the distribution of absorbed doses of each important organs of head and neck region in panoramic radiography. Radiation dosimetry at internal anatomic sites and skin surfaces of phantom (RT-210 Humanoid Head and Neck Section R) was performed with lithium fluoride (TLD-100R) thermoluminescent dosimeters according to change of kilovoltage (65 kVp, 75 kVp and 85 kVp) with 4 miliamperage and 20 second exposure time. The results obtained were as follows; Radiation absorbed doses of internal anatomic sites were presented the highest does of 1.04 mGy, 1.065 mGy and 2.09 mGy in nasopharynx, relatively high doses of 0.525 mGy, 0.59 mGy and 1.108 mGy in deep lobe of parotid gland, 0.481 mGy, 0.68 mGy and 1.191 mGy in submandibular gland. But there were comparatively low doses of 0.172 mGy and 0.128 mGy in eyes and thyroid gland that absorbed dose was estimated at 85kVp. Radiation absorbed doses of skin surfaces were presented the highest doses of 1.263 mGy, 1.538 mGy and 2.952 mGy in back side of first cervical vertebra and relatively high doses of 0.267 mGy, 0.401 mGy and 0.481 mGy in parotid gland. But there were comparatively low doses of 0.057 mGy, 0.068 mGy and 0.081 mGy in philtrum and 0.059 mGy in middle portion of chin that absorbed dose was estimated at 85 kVp. According to increase of kilovoltage, the radiation absorbed doses were increased 1.1 times when kilovoltage changes from 65 kVp to 75 kVp and 1.9 times when kilovoltage changes from 75 kVp to 85 kVp at internal anatomic sites. According to increase of kilovoltage, the radiation absorbed doses were increased 1.3 times when kilovoltage changes from 65 kVp to 75 kVp and 1.6 times when kilovoltage changes from 75 kVp to 85 kVp at skin surfaces.

  17. Sensitivity of MOS transistors to gamma and electron doses

    Energy Technology Data Exchange (ETDEWEB)

    Petr, I. (Ceske Vysoke Uceni Technicke, Prague (Czechoslovakia). Fakulta Jaderna a Fysikalne Inzenyrska); Gilar, O. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky)

    1985-03-01

    The threshold shift has been as a function of the properties of the SiO/sub 2/ layer, viz. oxide thickness and diffusion length of the charge carriers formed in the oxide layer. Experimental results obtained from gamma, fast electron, and fast neutron irradiation of MOS transistors having different oxide thickness are given. The theoretical results are compared with the measured data. The sensitivity of MOS transistors to gamma rays and fast electrons is given together with the energy dependence of radiation doses. The application of MOS transistors as dosemeters is discussed.

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

    Science.gov (United States)

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

    1999-09-01

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

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

    Science.gov (United States)

    Palm, Asa; Nilsson, Elisabeth; Herrnsdorf, Lars

    2010-01-28

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

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

    Science.gov (United States)

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

    2006-09-01

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

  1. 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

  2. A cyanocobalamin dosimeter for monitoring gamma-radiation doses of 0.1-2 kGy

    Science.gov (United States)

    Maged, A. F.; Hamza, M. S. A.; Saad, E. A.

    1997-08-01

    A simple dosimeter is described for measuring gamma-ray doses useful for insect sterilization, seed-sprouting inhibition and food shelf-life extensions. The red aqueous solution of cyanocobalamin (B 12) before irradiation, assumes a stable yellow color when irradiated. It shows a linear response of absorbance decrease with the dose over the range of 0.1-2.0 kGy when the concentration of cyanocobalamin is equal 0.09 mM. The radiation-induced color is analyzed spectrophotometrically at the maximum absorption band (361 nm). The absorption spectra, dose response and post-irradiation stability of the dosimeter are discussed.

  3. A cyanocobalamin dosimeter for monitoring gamma-radiation doses of 0.1-2 kGy

    Energy Technology Data Exchange (ETDEWEB)

    Maged, A.F. [National Centre for Radiation Research and Technology, Cairo (Egypt); Hamza, M.S.A.; Saad, E.A. [Ain Shams Univ., Cairo (Egypt). Faculty of Science

    1997-08-01

    A simple dosimeter is described for measuring gamma-ray doses useful for insect sterilization, seed-sprouting inhibition and food shelf-life extension. The red aqueous solution of cyanocobalamin (B{sub 12}) before irradiation, assumes a stable yellow color when irradiated. It shows a linear response of absorbance decrease with the dose over the rage of 0.1-2.0 kGy when the concentration of cyanocobalamin is equal 0.09 mM. The radiation-induced color is analyzed spectrophotometrically at the maximum absorption band (361 nm). The absorption spectra, dose response and post-irradiation stability of the dosimeter are discussed. (author).

  4. Gamma/neutron dose evaluation using Fricke gel and alanine gel dosimeters to be applied in boron neutron capture therapy.

    Science.gov (United States)

    Mangueira, T F; Silva, C F; Coelho, P R P; Campos, L L

    2010-01-01

    Gel dosimetry has been studied mainly for medical applications. The radiation induced ferric ions concentration can be measured by different techniques to be related with the absorbed dose. Aiming to assess gamma/thermal neutrons dose from research reactors, Fricke gel and alanine gel solutions produced at IPEN using 300 bloom gelatin were mixed with Na(2)B(4)O(7) salt, and the mixtures were irradiated at the beam hole #3 of the IEA-R1 research reactor, (BH#3) adapted to BNCT studies, and the dose-response was evaluated using spectrophotometry technique.

  5. Gamma Knife radiosurgery with CT image-based dose calculation.

    Science.gov (United States)

    Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Niranjan, Ajay; Kondziolka, Douglas; Flickinger, John; Lunsford, L Dade; Huq, M Saiful

    2015-11-08

    The Leksell GammaPlan software version 10 introduces a CT image-based segmentation tool for automatic skull definition and a convolution dose calculation algorithm for tissue inhomogeneity correction. The purpose of this work was to evaluate the impact of these new approaches on routine clinical Gamma Knife treatment planning. Sixty-five patients who underwent CT image-guided Gamma Knife radiosurgeries at the University of Pittsburgh Medical Center in recent years were retrospectively investigated. The diagnoses for these cases include trigeminal neuralgia, meningioma, acoustic neuroma, AVM, glioma, and benign and metastatic brain tumors. Dose calculations were performed for each patient with the same dose prescriptions and the same shot arrangements using three different approaches: 1) TMR 10 dose calculation with imaging skull definition; 2) convolution dose calculation with imaging skull definition; 3) TMR 10 dose calculation with conventional measurement-based skull definition. For each treatment matrix, the total treatment time, the target coverage index, the selectivity index, the gradient index, and a set of dose statistics parameters were compared between the three calculations. The dose statistics parameters investigated include the prescription isodose volume, the 12 Gy isodose volume, the minimum, maximum and mean doses on the treatment targets, and the critical structures under consideration. The difference between the convolution and the TMR 10 dose calculations for the 104 treatment matrices were found to vary with the patient anatomy, location of the treatment shots, and the tissue inhomogeneities around the treatment target. An average difference of 8.4% was observed for the total treatment times between the convolution and the TMR algorithms. The maximum differences in the treatment times, the prescription isodose volumes, the 12 Gy isodose volumes, the target coverage indices, the selectivity indices, and the gradient indices from the convolution

  6. Optical fiber sensor for low dose gamma irradiation monitoring

    Science.gov (United States)

    de Andrés, Ana I.; Esteban, Ã.`scar; Embid, Miguel

    2016-05-01

    An optical fiber gamma ray detector is presented in this work. It is based on a Terbium doped Gadolinium Oxysulfide (Gd2O2S:Tb) scintillating powder which cover a chemically etched polymer fiber tip. This etching improves the fluorescence gathering by the optical fiber. The final diameter has been selected to fulfill the trade-off between light gathering and mechanical strength. Powder has been encapsulated inside a microtube where the fiber tip is immersed. The sensor has been irradiated with different air Kerma doses up to 2 Gy/h with a 137Cs source, and the spectral distribution of the fluorescence intensity has been recorded in a commercial grade CCD spectrometer. The obtained signal-to-noise ratio is good enough even for low doses, which has allowed to reduce the integration time in the spectrometer. The presented results show the feasibility for using low cost equipment to detect/measure ionizing radiation as gamma rays are.

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

    Science.gov (United States)

    Tedgren, Åsa Carlsson; Carlsson, Gudrun Alm

    2013-04-21

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

  8. Combined scintillation detector for gamma dose rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Viererbl, L.; Novakova, O.; Jursova, L. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky)

    1990-01-01

    The specifications are described of a newly developed scintillation detector, essentially consisting of a plastic scintillator completed with inorganic scintillators ZnS(Ag) and NaI(Tl). The gamma dose rate is derived from the photomultiplier anode current. The composition and sizes of the scintillators and the capsule are selected so as to minimise the energy dependence errors and directional dependence errors of the detector response over a wide range of energies and/or angles. (author).

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

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  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. Calculation of absorbed dose in water by chemical Fricke dosimetry; Calculo de dose absorvida na agua por dosimetria quimica Fricke

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Adenilson Paiva, E-mail: adenilson-fisica@hotmail.com.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil); Meireles, Ramiro Conceicao [Fundacao do Cancer, Rio de Janeiro, RJ (Brazil)

    2016-07-01

    This work is the result of a laboratory activity performed in Radiological Sciences Laboratory (CRL), linked to the State University of Rio de Janeiro (UERJ). This practice aimed to determine the absorbed dose to water, through the primary calibration method called dosimetry Fricke, which consists of ferrous ions (Fe + 2) to ferric (Fe + 3), generated by water radiolysis products which is the structural change of water molecule caused by ionizing radiation. A spectrophotometer was used to extract data for analysis at a wavelength (λ) 304 and 224 nm with function of measuring the absorbance using bottles with irradiated and nonirradiated Fricke solution. (author)

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

    Directory of Open Access Journals (Sweden)

    Mohammad Mirzaei

    2015-04-01

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

  14. C IV ABSORBERS ALONG THE SIGHTLINES TO GAMMA-RAY BURSTS

    Directory of Open Access Journals (Sweden)

    N. Tejos

    2009-01-01

    Full Text Available We report on the statistics of strong (Wr > 0:15 A C IV absorbers at z = 1:5 3:5 toward high-redshift Gamma-Ray Bursts (GRBs. In contrast with a recent survey for strong Mg II absorption systems at z < 2, we nd that the number of C IV absorbers per unit redshift dN=dz does not show any signi cant deviation from previous surveys using QSOs as background sources. Although the results for Mg II and C IV absorbers along GRB sightlines appear to contradict one another, we note that the surveys are nearly disjoint: the C IV survey corresponds to higher redshift and more highly ionized gas than the Mg II survey. Nevertheless, analysis on larger statistical samples may constrain properties of the galaxies hosting these metals (e.g. mass, dust content and/or the coherence-length of the gas giving rise to the metal-line absorption.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Shokofeh Pirdomooie

    2016-07-01

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

  17. Comment on ‘Development of a primary standard for absorbed dose from unsealed radionuclide solutions’

    Science.gov (United States)

    Ross, C. K.

    2017-08-01

    The authors of a recent paper (Billas et al 2016 Metrologia 53 1259-71) describe the development of a primary standard for the absorbed dose in an aqueous solution containing the radionuclide 90Y. By positioning a thin-window extrapolation chamber near the surface of the solution they determine the absorbed dose in the air cavity. Using Monte Carlo calculations and knowledge of the 90Y β-ray spectrum they relate the absorbed dose in air to that in the aqueous solution. I point out that there is no need to develop a new standard for this problem because knowledge of the activity of the radionuclide, combined with its decay characteristics, is adequate to establish a primary standard for the absorbed dose in water. Furthermore, the uncertainty using this approach is significantly smaller than that achieved using the authors’ technique. Results from Monte Carlo calculations are reported that: (1) determine the minimum phantom size required to establish charged particle equilibrium; (2) show that the authors have neglected bremsstrahlung losses from the phantom; (3) show why the authors’ results are very sensitive to the air gap between the solution and the window of the ionization chamber. Finally, I consider the problem of calibrating secondary detectors against the primary standard.

  18. Gamma radiation measurements and dose rates in commercially-used natural tiling rocks (granites)

    CERN Document Server

    Tzortzis, M; Christofides, S; Christodoulides, G

    2003-01-01

    The gamma radiation in samples of a variety of natural tiling rocks (granites) imported in Cyprus for use in the building industry was measured, employing high-resolution gamma-ray spectroscopy. The rock samples were pulverized, sealed in 1 litre plastic Marinelli beakers, and measured in the laboratory with a live-time between 10 and 14 hours each. From the measured gamma-ray spectra, activity concentrations were determined for Th-232 (range from 1 to 906 Bq/kg), U-238 (from 1 to 588 Bq/kg) and K-40 (from 50 to 1606 Bq/kg). Elemental concentrations mean values of (35.2 +- 8.4) ppm, (6.2 +- 1.8) ppm and (4.0 +- 0.2) % were deduced, for thorium, uranium and potassium, respectively. The total absorbed dose rates in air calculated from the concentrations of the three radionuclides, Th-232 and U-238 series and K-40, ranged from 7 to 1209 nGy/h for full utilization of the materials, from 4 to 605 nGy/h for half utilization and from 2 to 302 nGy/h for one quarter utilization. The total effective dose rates per pers...

  19. Inter- and intrafractional dose uncertainty in hypofractionated Gamma Knife radiosurgery.

    Science.gov (United States)

    Kim, Taeho; Sheehan, Jason; Schlesinger, David

    2016-03-08

    The purpose of this study is to evaluate inter- and intrafractional dose variations resulting from head position deviations for patients treated with the Extend relocatable frame system utilized in hypofractionated Gamma Knife radiosurgery (GKRS). While previous reports characterized the residual setup and intrafraction uncertainties of the system, the dosimetric consequences have not been investigated. A digital gauge was used to measure the head position of 16 consecutive Extend patients (62 fractions) at the time of simulation, before each fraction, and immediately following each fraction. Vector interfraction (difference between simulation and prefraction positions) and intrafraction (difference between postfraction and prefraction positions) shifts in patient position were calculated. Planned dose distributions were shifted by the offset to determine the time-of-treatment dose. Variations in mean and maximum target and organ at risk (OAR) doses as a function of positional shift were evaluated. The mean vector interfraction shift was 0.64 mm (Standard Deviation (SD): 0.25 mm, maximum: 1.17 mm). The mean intrafraction shift was 0.39 mm (SD: 0.25 mm, maximum: 1.44 mm). The mean variation in mean target dose was 0.66% (SD: 1.15%, maximum: 5.77%) for inter-fraction shifts and 0.26% (SD: 0.34%, maximum: 1.85%) for intrafraction shifts. The mean variation in maximum dose to OARs was 7.15% (SD: 5.73%, maximum: 30.59%) for interfraction shifts and 4.07% (SD: 4.22%, maximum: 17.04%) for intrafraction shifts. Linear fitting of the mean variation in maximum dose to OARs as a function of position yielded dose deviations of 10.58%/mm for interfractional shifts and 7.69%/mm for intrafractional shifts. Positional uncertainties when per-forming hypofractionated Gamma Knife radiosurgery with the Extend system are small and comparable to frame-based uncertainties (< 1 mm). However, the steep dose gradient characteristics of GKRS mean that the dosimetric consequences of

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

    Science.gov (United States)

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

    2016-03-01

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

  1. Gamma-Ray Dose Measurement with Radio-Photoluminescence Glass Dosimeter in Mixed Radiation Field for BNCT

    Science.gov (United States)

    Hiramatsu, K.; Yoshihashi, S.; Kusaka, S.; Sato, F.; Hoashi, E.; Murata, I.

    2017-09-01

    Accelerator based neutron sources (ABNS) are being developed as the next generation neutron irradiation system for BNCT. From the ABNS, unnecessary gamma-rays will be generated by neutron capture reactions, as well as fast neutrons. To control the whole-body radiation dose to the patient, measurement of gamma-ray dose in the irradiation room is necessary. In this study, the objective is to establish a method to measure gamma-ray dose separately in a neutron/gamma mixed field by using RPL glass dosimeter. For this purpose, we proposed a lead filter method which uses a pair of RPL glasses with and without a lead filter outside. In order to realize this method, the basic characteristics of glass dosimeter was verified in the gamma-ray field, before adapting it in the mixture field. From the result of the experiment using the lead filter, the simulation result especially for the case with a lead filter overestimated the absorbed does obtained from measurement. We concluded that the reason of the discrepancy is caused by existence of gradient of the dose distribution in the glass, and the difference of sensitivity to low-energy photon between measurement and theory.

  2. Development of autonomous gamma dose logger for environmental monitoring.

    Science.gov (United States)

    Jisha, N V; Krishnakumar, D N; Surya Prakash, G; Kumari, Anju; Baskaran, R; Venkatraman, B

    2012-03-01

    Continuous monitoring and archiving of background radiation levels in and around the nuclear installation is essential and the data would be of immense use during analysis of any untoward incidents. A portable Geiger Muller detector based autonomous gamma dose logger (AGDL) for environmental monitoring is indigenously designed and developed. The system operations are controlled by microcontroller (AT89S52) and the main features of the system are software data acquisition, real time LCD display of radiation level, data archiving at removable compact flash card. The complete system operates on 12 V battery backed up by solar panel and hence the system is totally portable and ideal for field use. The system has been calibrated with Co-60 source (8.1 MBq) at various source-detector distances. The system is field tested and performance evaluation is carried out. This paper covers the design considerations of the hardware, software architecture of the system along with details of the front-end operation of the autonomous gamma dose logger and the data file formats. The data gathered during field testing and inter comparison with GammaTRACER are also presented in the paper. AGDL has shown excellent correlation with energy fluence monitor tuned to identify (41)Ar, proving its utility for real-time plume tracking and source term estimation.

  3. Out of field dose during Gamma Knife treatment: a paediatric case study

    Science.gov (United States)

    Moutrie, V.; Grace, M.; Izard, M. A.; Fuller, J. W.

    2017-01-01

    An 11-year-old girl with an arteriovenous malformation (AVM) was referred for Gamma Knife treatment. As this would be the first paediatric treatment in Australia, additional investigations were undertaken into out of field dose to assure the best possible long term outcome for the patient. A phantom was constructed from water equivalent materials to simulate the patient. A target volume was defined to emulate the size and location of the AVM visible in diagnostic images. An ionisation chamber and EBT3 Gafchromic film were used to record absorbed dose at strategic points both on the surface and at depth within the phantom. On the day of treatment, EBT3 Gafchromic film was used to conduct in vivo dosimetry. The pre-treatment phantom measurements matched the planning system for the cranial section (the only modelled section) and no measurable dose above background was detected in the extracranial sites. In vivo measurements of the lenses returned doses of up to 2 cGy for imaging and 8 cGy for treatment which was also consistent with the planned dose. Dose to the thyroid, chest and abdomen was not measurable above background.

  4. 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

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Science.gov (United States)

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

    1989-01-01

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

  7. Formation of radical cations and dose response of alpha-terthiophene-cellulose triacetate films irradiated by electrons and gamma rays

    CERN Document Server

    Emmi, S S; Ceroni, P; D'Angelantonio, M; Lavalle, M; Fuochi, P G; Kovács, A

    2002-01-01

    The radiation-induced UV-vis spectrum of alpha-terthiophene radical cation in solid is reported. The radical cation initiates an oligomerization in the CTA matrix producing permanently coloured conjugated polarons. The specific net absorbance at 465 nm is linearly related with dose up to 2x10 sup sup 6 sup sup G y, for electrons and gamma irradiation. The decrease of the UV typical absorption (355 nm) and of four IR bands of alpha-terthiophene is linear with dose, as well. Although sensitivity is influenced by dose rate, it turned out that a linear relationship holds between sensitivity and log dose rate, in the range from 2 to 10 sup sup 5 Gy, min. These findings suggest a potential application of the system for dosimetric purposes over a wide range of dose and dose rate.

  8. Assessment of effective absorbed dose of (111)In-DTPA-Buserelin in human on the basis of biodistribution rat data.

    Science.gov (United States)

    Lahooti, Afsaneh; Shanehsazzadeh, Saeed; Jalilian, Amir Reza; Tavakoli, Mohammad Bagher

    2013-04-01

    In this study, the effective absorbed dose to human organs was estimated, following intra vascular administration of (111)In-DTPA-Buserelin using biodistribution data from rats. Rats were sacrificed at exact time intervals of 0.25, 0.5, 1, 2, 4 and 24 h post injections. The Medical Internal Radiation Dose formulation was applied to extrapolate from rats to humans and to project the absorbed radiation dose for various human organs. From rat data, it was estimated that a 185-MBq injection of (111)In-DTPA-Buserelin into the human might result in an estimated absorbed dose of 24.27 mGy to the total body and the highest effective absorbed dose was in kidneys, 28.39 mSv. The promising results of this study emphasises the importance of absorbed doses in humans estimated from data on rats.

  9. Fetal and maternal absorbed dose estimates for positron-emitting molecular imaging probes.

    Science.gov (United States)

    Xie, Tianwu; Zaidi, Habib

    2014-09-01

    PET and hybrid (PET/CT and PET/MR) imaging currently play a pivotal role in clinical diagnosis, staging and restaging, treatment, and surveillance of several diseases. As such, limiting the radiation exposure of special patients, such as pregnant women, from PET procedures is an important challenge that needs to be appropriately addressed because of the high sensitivity of the developing embryo/fetus to ionizing radiation. Therefore, accurate radiation dose calculation for the embryo/fetus and pregnant patient from common positron-emitting radiotracers is highly desired. To obtain representative estimates of radiation dose to the human body, realistic biologic and physical models should be used. In this work, we evaluate the S values of 9 positron-emitting radionuclides ((11)C, (13)N, (15)O, (18)F, (64)Cu, (68)Ga, (82)Rb, (86)Y, and (124)I) and the absorbed and effective doses for 21 positron-emitting labeled radiotracers using realistic anthropomorphic computational phantoms of early pregnancy and at 3-, 6-, and 9-mo of gestation and the most recent biokinetic data available. The Monte Carlo N-Particle eXtended general-purpose Monte Carlo code was used for radiation transport simulation. The absorbed dose to the pregnant model is less influenced by the gestation for most organs or tissues, but the anatomic changes of the maternal body increases the effective dose for some radiotracers. For (18)F-FDG, the estimated absorbed doses to the embryo/fetus are 3.05E-02, 2.27E-02, 1.50E-02, and 1.33E-02 mGy/MBq at early pregnancy and 3-, 6-, and 9-mo gestation, respectively. The absorbed dose is nonuniformly distributed in the fetus and would be 1.03-2 times higher in the fetal brain than in other fetal soft tissues. The generated S values can be exploited to estimate the radiation dose delivered to pregnant patients and the embryo/fetus from various PET radiotracers used in clinical and research settings. The generated dosimetric database of radiotracers using new

  10. Comparison of the neutron ambient dose equivalent and ambient absorbed dose calculations with different GEANT4 physics lists

    Science.gov (United States)

    Ribeiro, Rosane Moreira; Souza-Santos, Denison

    2017-10-01

    A comparison between neutron physics lists given by GEANT4, is made in the calculation of the ambient dose equivalent, and ambient absorbed dose, per fluence conversion coefficients (H* (10) / ϕ and D* (10) / ϕ) for neutrons in the range of 10-9 MeV to 15 MeV. Physics processes are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles. Results obtained for QBBC, QGSP_BERT, QGSP_BIC and Neutron High Precision physics lists are compared with values published in ICRP 74 and previously published articles. Neutron high precision physics lists showed the best results in the studied energy range.

  11. 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)

  12. Dose response of multiple parameters for calyculin A-induced premature chromosome condensation in human peripheral blood lymphocytes exposed to high doses of cobalt-60 gamma-rays.

    Science.gov (United States)

    Lu, Xue; Zhao, Hua; Feng, Jiang-Bin; Zhao, Xiao-Tao; Chen, De-Qing; Liu, Qing-Jie

    2016-09-01

    Many studies have investigated exposure biomarkers for high dose radiation. However, no systematic study on which biomarkers can be used in dose estimation through premature chromosome condensation (PCC) analysis has been conducted. The present study aims to screen the high-dose radiation exposure indicator in calyculin A-induced PCC. The dose response of multiple biological endpoints, including G2/A-PCC (G2/M and M/A-PCC) index, PCC ring (PCC-R), ratio of the longest/shortest length (L/L ratio), and length and width ratio of the longest chromosome (L/B ratio), were investigated in calyculin A-induced G2/A-PCC spreads in human peripheral blood lymphocytes exposed to 0-20Gy (dose-rate of 1Gy/min) cobalt-60 gamma-rays. The G2/A-PCC index was decreased with enhanced absorbed doses of 4-20Gy gamma-rays. The G2/A PCC-R at 0-12Gy gamma-rays conformed to Poisson distribution. Three types of PCC-R were scored according to their shape and their solidity or hollowness. The frequencies of hollow PCC-R and PCC-R including or excluding solid ring in G2/A-PCC spreads were enhanced with increased doses. The length and width of the longest chromosome, as well as the length of the shortest chromosome in each G2/M-PCC or M/A-PCC spread, were measured. All L/L or L/B ratios in G2/M-PCC or M/A-PCC spread increased with enhanced doses. A blind test with two new irradiated doses was conducted to validate which biomarker could be used in dose estimation. Results showed that hollow PCC-R and PCC-R including solid ring can be utilized for accurate dose estimation, and that hollow PCC-R was optimal for practical application.

  13. Dose verification to cochlea during gamma knife radiosurgery of acoustic schwannoma using MOSFET dosimeter

    Directory of Open Access Journals (Sweden)

    Sunil D Sharma

    2012-01-01

    Conclusion: The measured dose values were found in good agreement with the dose values calculated using the TPS. The MOSFET dosimeter can be a suitable choice for routine dose verification in the Gamma Knife radiosurgery.

  14. 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

  15. 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.

  16. Tyrosol and hydroxytyrosol are absorbed from moderate and sustained doses of virgin olive oil in humans.

    Science.gov (United States)

    Miró-Casas, E; Covas, M-I; Fitó, M; Farré-Albadalejo, M; Marrugat, J; de la Torre, R

    2003-01-01

    To investigate the absorption of tyrosol and hydroxytyrosol from moderate and sustained doses of virgin olive oil consumption. The study also aimed to investigate whether these phenolic compounds could be used as biomarkers of virgin olive oil intake. Ingestion of a single dose of virgin olive oil (50 ml). Thereafter, for a week, participants followed their usual diet which included 25 ml/day of the same virgin olive oil as the source of raw fat. Unitat de Recerca en Farmacologia. Institut Municipal d'Investigació Mèdica (IMIM). Seven healthy volunteers. An increase in 24 h urine of tyrosol and hydroxytyrosol, after both a single-dose ingestion (50 ml) and short-term consumption (one week, 25 ml/day) of virgin olive oil (P<0.05) was observed. Urinary recoveries for tyrosol were similar after a single dose and after sustained doses of virgin olive oil. Mean recovery values for hydroxytyrosol after sustained doses were 1.5-fold those obtained after a single 50 ml dose. Tyrosol and hydroxytyrosol are absorbed from realistic doses of virgin olive oil. With regard to the dose-effect relationship, 24 h urinary tyrosol seems to be a better biomarker of sustained and moderate doses of virgin olive oil consumption than hydroxytyrosol.

  17. Dose calculation method with 60-cobalt gamma rays in total body irradiation

    CERN Document Server

    Scaff, L A M

    2001-01-01

    Physical factors associated to total body irradiation using sup 6 sup 0 Co gamma rays beams, were studied in order to develop a calculation method of the dose distribution that could be reproduced in any radiotherapy center with good precision. The method is based on considering total body irradiation as a large and irregular field with heterogeneities. To calculate doses, or doses rates, of each area of interest (head, thorax, thigh, etc.), scattered radiation is determined. It was observed that if dismagnified fields were considered to calculate the scattered radiation, the resulting values could be applied on a projection to the real size to obtain the values for dose rate calculations. In a parallel work it was determined the variation of the dose rate in the air, for the distance of treatment, and for points out of the central axis. This confirm that the use of the inverse square law is not valid. An attenuation curve for a broad beam was also determined in order to allow the use of absorbers. In this wo...

  18. Discovery of Rapidly Moving Partial X-ray Absorbers within gamma Cassiopeiae

    CERN Document Server

    Hamaguchi, K; Russell, C M P; Petre, R; Enoto, T; Morihana, K; Ishida, M

    2016-01-01

    Gamma Cassiopeiae is an enigmatic Be star with unusually strong hard X-ray emission. The Suzaku observatory detected six rapid X-ray spectral hardening events called "softness dips" in a ~100 ksec duration observation in 2011. All the softness dip events show symmetric softness ratio variations, and some of them have flat bottoms apparently due to saturation. The softness dip spectra are best described by either ~40% or ~70% partial covering absorption to kT ~12 keV plasma emission by matter with a neutral hydrogen column density of ~2-8e21 cm-2, while the spectrum outside of these dips is almost free of absorption. This result suggests the presence of two distinct X-ray emitting spots in the gamma Cas system, perhaps on a white dwarf companion with dipole mass accretion. The partial covering absorbers may be blobs in the Be stellar wind, the Be disk, or rotating around the white dwarf companion. Weak correlations of the softness ratios to the hard X-ray flux suggest the presence of stable plasmas at kT ~0.9 ...

  19. Radioactivity Levels and Gamma-Ray Dose Rate in Soil Samples from Kohistan (Pakistan) Using Gamma-Ray Spectrometry

    Institute of Scientific and Technical Information of China (English)

    Hasan M. Khan; M. Ismail; K. Khan; P. Akhter

    2011-01-01

    The analysis of naturally occurring radionuclides (226Ra, 232Th and 40K) and an anthropogenic radionuclide 137Cs is carried out in some soil samples collected from Kohistan district of N.W.F.P. (Pakistan), using gamma-ray spectrometry. The gamma spectrometry is operated using a high purity Germanium (HPGe) detector coupled with a computer based high resolution multi channel analyzer. The speciSc activity in soil ranges from 24.72 to 78.48Bq·kg-1 for 226Ra, 21.73 to 75.28Bq·kg-1 for 232Th, 7.06 to 14.9Bq·kg-1 for l37Cs and 298.46 to 570.77Bq·kg-1 for 40K with the mean values of 42.11, 43.27, 9.5 and 418.27Bq·kg-1, respectively. The radium equivalent activity in all the soil samples is lower than the safe limit set in the OECD report (370Bq·kg-1). Man-made radionuclide 137Cs is also present in detectable amount in all soil samples. Presence of 137Cs indicates that the samples in this remote area also receive some fallout from nuclear accident in Chernobyl power plant in 1986. The internal and external hazard indices have the mean values of 0.48 and 0.37 respectively. Absorbed dose rates and effective dose equivalents are also determined for the samples. The concentration of radionuclides found in the soil samples during the present study is nominal and does not pose any potential health hazard to the general public.

  20. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  2. 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...

  3. Determination of the [gamma]-ray dose in an epithermal neutron beam

    Energy Technology Data Exchange (ETDEWEB)

    Raaijmakers, C.P.J.; Konijnenberg, M.W.; Mijnheer, B.J. (Netherlands Cancer Inst., Amsterdam (Netherlands)); Stecher-Rasmussen, F.; Verhagen, H. (Netherlands Energy Research Foundation, Petten (Netherlands))

    1993-01-01

    Neutron beams used for Boron Neutron Capture Therapy (BNCT) are always accompanied by photons. These two irradiation components have different relative biological effectiveness. Therefore it is necessary to determine the neutron and photon absorbed dose in the mixed field separately. All gamma-ray detectors however are also sensitive for neutrons. In this work preliminary results are presented using TLD-700 chips, a Mg(Ar) ionisation chamber and a GM-counter to determine the gamm-ray component in a mixed beam of gamma-rays and neutrons. The results show a good agreement between the GM-counter and the ionisation chamber, indicating a small realtive neutron sensitivity (k[sub u]) for these detectors. The sensitivity of TLD-700 for thermal neutrons however gives rise to a detector response for which a correction is necessary. The uncertainty however in the relative gamma-ray sensitivity (h[sub u]) of the detectors is at this moment too large to determine accurate values of the relative neutron sensitivities. (orig.).

  4. Radon exhalation rates and gamma doses from ceramic tiles.

    Science.gov (United States)

    O'Brien, R S; Aral, H; Peggie, J R

    1998-12-01

    This study was carried out to assess the possible radiological hazard resulting from the use of zircon in glaze applied to tiles used in buildings. The 226Ra content of various stains and glazing compounds was measured using gamma spectroscopy and the 222Rn exhalation rates for these materials were measured using adsorption on activated charcoal. The radon exhalation rates were found to be close to or less than the minimum detectable values for the equipment used. This limit was much lower than the estimated exhalation rates, which were calculated assuming that the parameters controlling the emanation and diffusion of 222Rn in the materials studied were similar to those of soil. This implied that the 222Rn emanation coefficients and/or diffusion coefficients for most of the materials studied were very much lower than expected. Measurements on zircon powders showed that the 222Rn emanation coefficient for zircon was much lower than that for soil, indicating that only a small fraction of the 222Rn produced by the decay of 226Ra was able to escape from the zircon grains. The estimated increase in radon concentration in room air and the estimated external gamma radiation dose resulting from the use of zircon glaze are both much lower than the relevant action level and dose limit.

  5. Neutron and gamma ray total dose rate determination using anisn

    Science.gov (United States)

    Amin, E.; Ashoub, N.; Elkady, A.

    1994-07-01

    The National Center for Nuclear Safety and Radiation Control is in the process of acquiring a computer software library based mainly on internationally widely used computer codes. These codes are to be used as basic tools in safety analysis and radiation control and risk assessment. A complementary part of this activity is to validate the computer codes and set standard procedures with the limits of confidence for the different areas of applications of the one or the other code or set of codes. The present work has been then initiated in order to develop a standard shielding calculating procedure to be applied for the different applications of interest to the center, namely: shielding of nuclear installations, such as the ET-RR-1 reactor, the gamma unit, nuclear accelerator, radiotherapy units; shielding of nuclear sources (mainly neutron and gamma sources); shielding of transportation containers. In developing such a standard method, the sources of error to the final results (i.e. the dose rate and dose rate distribution) have to been identified and the error to be quantified. Through applying the developed procedure to benchmark PWR shielding problems, and to documented results for fission sources in water and concrete, the levels of confidence of the procedure in different application areas have been set.

  6. Neutron and gamma ray total dose rate determination using ANISN

    Energy Technology Data Exchange (ETDEWEB)

    Amin, E.; Elkady, A. [Atomic Energy Authority, Cairo (Egypt). National Center for Nuclear Safety and Radiation Control; Ashoub, N. [Nuclear Research Center, Cairo (Egypt)

    1994-07-01

    The National Center for Nuclear Safety and Radiation Control is in the process of acquiring a computer software library based mainly on internationally widely used computer codes. These codes are to be used as basic tools in safety analysis and radiation control and risk assessment. A complementary part of this activity is to validate the computer codes and set standard procedures with the limits of confidence for the different areas of applications of the one or the other code or set of codes. The present work has been then initiated in order to develop a standard shielding calculating procedure to be applied for the different applications of interest to the center, namely: shielding of nuclear installations, such as the ET-RR-1 reactor, the gamma unit, nuclear accelerator, radiotherapy units; shielding of nuclear sources (mainly neutron and gamma sources); shielding of transportation containers. In developing such a standard method, the sources of error to the final results (i.e. the dose rate and dose rate distribution) have to be identified and the error to be quantified. Through applying the developed procedure to benchmark PWR shielding problems, and to documented results for fission sources in water and concrete, the levels of confidence of the procedure in different application areas have been set. (author).

  7. 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)

  8. Identification of QTL affecting a piglet’s ability to acquire and absorb gamma-immunoglobulin from colostrum

    Science.gov (United States)

    Consumption of an adequate amount of colostrum is critical to a piglet’s survival and productivity. The immunocrit is an inexpensive rapid measurement of the amount of gamma-immunoglobulin absorbed by a piglet. Genetic analysis of immunocrits on 5,312 piglets indicated that the heritabilities (se) f...

  9. 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.

  10. 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.

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

    Science.gov (United States)

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

    2016-09-24

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

  12. 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)

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

    Science.gov (United States)

    Kramer, Richard

    2011-08-01

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

  14. Specific gamma-ray dose constants for nuclides important to dosimetry and radiological assessment

    Energy Technology Data Exchange (ETDEWEB)

    Unger, L.M.; Trubey, D.K.

    1982-05-01

    Tables of specific gamma-ray dose constants (the unshielded gamma-ray dose equivalent rate at 1 m from a point source) have been computed for approximately 500 nuclides important to dosimetry and radiological assessment. The half life, the mean attenuation coefficient, and thickness for a lead shield providing 95% dose equivalent attenuation are also listed.

  15. Specific gamma-ray dose constants for nuclides important to dosimetry and radiological assessment

    Energy Technology Data Exchange (ETDEWEB)

    Unger, L.M.; Trubey, D.K.

    1981-09-01

    Tables of specific gamma-ray dose constants (the unshielded gamma-ray dose equivalent rate at 1 m from a point source) have been computed for approximately 500 nuclides important to dosimetry and radiological assessment. The half life, the mean attenuation coefficient, and thickness for a lead shield providing 95% dose equivalent attenuation are also listed.

  16. Experimental and Simulation of Gamma Radiation Dose Rate for High Exposure Building Material

    CERN Document Server

    Abbasi, Akbar

    2015-01-01

    Natural radioactivity concentrations in high exposure building materials are commonly used in Iran, which is measured a direct exposure by using {\\gamma}-ray spectrometry. The values for 226Ra, 232Th and 40K were in the ranges 3.8 - 94.2, 6.5 - 172.2 and 556.9 - 1539.2 Bqkg-1, respectively. The absorbed dose rates in the standard dwelling room due to 238U, 232Th series and 40K were calculated with MCNPX code. The simulation and experimental results were between 7.95 - 41.74 and 8.36 - 39.99 nGy h-1, respectively. These results were compared with experimental outing and there was overlap closely. The simulation results are able to develop for any kind of dwelling places.

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

    DEFF Research Database (Denmark)

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

    1977-01-01

    in polymeric solutions can be cast into flexible free-standing thin films of uniform thickness and reproducible response to ultraviolet and ionizing radiation. The increase in optical density versus energy deposited by radiation is linear over a wide range of doses and is for practical purposes independent...... of many polymeric systems in industrial radiation processing. The result is that errors due to energy dependence of response of the radiation sensor are effectively reduced, since the spectral sensitivity of the dose meter matches that of the polymer of interest, over a wide range of photon and electron...

  18. Low Dose Gamma Irradiation Potentiates Secondary Exposure to Gamma Rays or Protons in Thyroid Tissue Analogs

    Energy Technology Data Exchange (ETDEWEB)

    Green, Lora M

    2006-05-25

    We have utilized our unique bioreactor model to produce three-dimensional thyroid tissue analogs that we believe better represent the effects of radiation in vivo than two-dimensional cultures. Our thyroid model has been characterized at multiple levels, including: cell-cell exchanges (bystander), signal transduction, functional changes and modulation of gene expression. We have significant preliminary data on structural, functional, signal transduction and gene expression responses from acute exposures at high doses (50-1000 rads) of gamma, protons and iron (Green et al., 2001a; 2001b; 2002a; 2002b; 2005). More recently, we used our DOE funding (ending Feb 06) to characterize the pattern of radiation modulated gene expression in rat thyroid tissue analogs using low-dose/low-dose rate radiation, plus/minus acute challenge exposures. Findings from these studies show that the low-dose/low-dose rate “priming” exposures to radiation invoked changes in gene expression profiles that varied with dose and time. The thyrocytes transitioned to a “primed” state, so that when the tissue analogs were challenged with an acute exposure to radiation they had a muted response (or an increased resistance) to cytopathological changes relative to “un-primed” cells. We measured dramatic differences in the primed tissue analogs, showing that our original hypothesis was correct: that low dose gamma irradiation will potentiate the repair/adaptation response to a secondary exposure. Implications from these findings are that risk assessments based on classical in vitro tissue culture assays will overestimate risk, and that low dose rate priming results in a reduced response in gene expression to a secondary challenge exposure, which implies that a priming dose provides enhanced protection to thyroid cells grown as tissue analogs. If we can determine that the effects of radiation on our tissue analogs more closely resemble the effects of radiation in vivo, then we can better

  19. 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.

  20. 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.

  1. Dose-response curve for blood exposed to gamma-neutron mixed field by conventional cytogenetic method

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Jose Odinilson de C.; Souza, Priscilla L.G.; Santos, Joelan A.L.; Vilela, Eudice C.; Lima, Fabiana F., E-mail: jodinilson@cnen.gov.b, E-mail: fflima@cnen.gov.b, E-mail: jasantos@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Calixto, Merilane S.; Santos, Neide, E-mail: santos_neide@yahoo.com.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Genetica

    2009-07-01

    There is increasing concern about airline crew members (about one million worldwide) are exposed to measurable neutrons doses. Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations (dicentrics, centric rings and acentric fragments) in mytogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage in peripheral blood lymphocytes are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure. Since radiological accidents are not common, not all nations feel that it is economically justified to maintain biodosimetry competence. However, dependable access to biological dosimetry capabilities is completely critical in event of an accident. In this paper the dose-response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to neutron-gamma mixes field. Blood was obtained from one healthy donor and exposed to two neutron-gamma mixed field from sources {sup 241}AmBe (20 Ci) at the Neutron Calibration Laboratory (NCL-CRCN/NE-PE-Brazil). The evaluated absorbed doses were 0.2 Gy; 1.0 Gy and 2.5 Gy. The dicentric chromosomes were observed at metaphase, following colcemid accumulation and 1000 well-spread metaphase figures were analyzed for the presence of dicentrics by two experienced scorers after painted by giemsa 5%. Our preliminary results showed a linear dependence between radiations absorbed dose and dicentric chromosomes frequencies. Dose-response curve described in this paper will contribute to the construction of calibration curve that will be used in our laboratory for biological dosimetry. (author)

  2. Thermoluminescent characteristic of MWCVD diamond films exposed to gamma dose

    Energy Technology Data Exchange (ETDEWEB)

    Gastelum, S.; Chernov, V.; Melendrez, R.; Barboza F, M. [Centro de Investigacion en Fisica, Universidad de Sonora, A.P. 5-088, 83190 Hermosillo, Sonora (Mexico); Cruz Z, E. [ICN-UNAM, A.P. 70-543, 04510 Mexico D.F. (Mexico)

    2006-07-01

    The thermoluminescence measurements of microwave plasma assisted CVD diamond of 6 and 12 {mu}m thick films grown on (100) silicon substrates indicated the existence of a suitable thermoluminescence dosimetric peak around 310 C. The range of linearity of the 6 {mu}m diamond sample exposed to 0.67 Gy/min {sup 60} Co gamma radiation is observed up to 125 Gy being non -linear for higher doses. The 12 {mu} m displayed lower thermoluminescence efficiency as compared to the 6 {mu}m specimen. The discrepancy was attributed to the non uniform distribution- of nucleated diamond on the substrate as revealed by SEM micrograph of the samples. The thermoluminescence behaviour of the samples exhibited very low thermal fading and show a good reproducibity of the thermoluminescence signal. The kinetics parameters were calculated by Initial Rise and Chen methods. (Author)

  3. 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)

  4. Discovery of Rapidly Moving Partial X-ray Absorbers within Gamma Cassiopeiae

    Science.gov (United States)

    Hamaguchi, K.; Oskinova, L.; Russell, C. M. P.; Petre, R.; Enoto, T.; Morihana, K.; Ishida, M.

    2016-12-01

    Gamma Cassiopeiae is an enigmatic Be star with unusually strong hard X-ray emission. The Suzaku observatory detected six rapid X-ray spectral hardening events called “softness dips” in a ˜100 ks observation in 2011. All the softness dip events show symmetric softness-ratio variations, and some of them have flat bottoms apparently due to saturation. The softness dip spectra are best described by either ˜40% or ˜70% partial covering absorption to kT ˜ 12 keV plasma emission by matter with a neutral hydrogen column density of ˜(2-8) × 1021 cm-2, while the spectrum outside these dips is almost free of absorption. This result suggests the presence of two distinct X-ray-emitting spots in the γ Cas system, perhaps on a white dwarf (WD) companion with dipole mass accretion. The partial covering absorbers may be blobs in the Be stellar wind, the Be disk, or rotating around the WD companion. Weak correlations of the softness ratios to the hard X-ray flux suggest the presence of stable plasmas at kT ˜ 0.9 and 5 keV, which may originate from the Be or WD winds. The formation of a Be star and WD binary system requires mass transfer between two stars; γ Cas may have experienced such activity in the past.

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

    Energy Technology Data Exchange (ETDEWEB)

    Joensson, Helene

    2003-10-01

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

  6. Effect of gamma-ray irradiation at low doses on the performance of PES ultrafiltration membrane

    Science.gov (United States)

    Zhang, Xue; Niu, Lixia; Li, Fuzhi; Yu, Suping; Zhao, Xuan; Hu, Hongying

    2016-10-01

    The influence of gamma irradiation on the performance of polyether sulfone (PES) ultrafiltration (UF) membrane was investigated at low absorbed doses (0-75 kGy) using a cobalt source. The performance of the UF membranes was tested using low level radioactive wastewater (LLRW) containing three types of surfactants (anionic, cationic and nonionic surfactants). The physical and chemical properties of membrane surface were analyzed, and relationships between these properties and separation performance and fouling characteristics were determined. At 10-75 kGy irradiation, there were no significant changes observed in the membrane surface roughness or polymer functional groups, however the contact angle decreased sharply from 92° to ca. 70° at irradiation levels as low as 10 kGy. When membranes were exposed to the surfactant-containing LLRW, the flux decreased more sharply for higher dosed irradiated membranes, while flux in virgin membranes increased during the filtration processes. The study highlights that fouling properties of membrane may be changed due to the changes of surface hydrophilicity at low dose irradiation, while other surface properties and retentions remain stable. Therefore, a membrane fouling test with real or simulated wastewater is recommended to fully evaluate the membrane irradiation resistance.

  7. 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.

  8. Reply to Comment on ‘Development of a primary standard for absorbed dose from unsealed radionuclide solutions’

    Science.gov (United States)

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

    2017-08-01

    This article is a reply to the comment from Ross (2017 Metrologia 54 610) on our paper (Billas et al 2016 Metrologia 53 1259) ‘Development of a primary standard for absorbed dose from unsealed radionuclide solutions’.

  9. 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.

  10. 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.

  11. 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.

  12. Total and secondary gamma doses in ilmenite-limonite concrete biological shields

    Energy Technology Data Exchange (ETDEWEB)

    Makarious, A.S. (AEA, Cairo (Egypt). Reactor and Neutron Physics Dept.); El-Kolaly, M.A. (AEA, Cairo (Egypt). Radiation Protection Dept.); Bashter, I.I. (Zagazig Univ. (Egypt). Physics Dept.); Kansouh, W.A. (AEA, Cairo (Egypt). Nuclear Research Centre)

    1991-10-01

    The attenuation and distribution of total gamma ray doses in a bulk shield of ilmenite-limonite concrete of density 2.9 g cm{sup -3} have been measured. Direct, cadmium filtered and B{sub 4}C filtered collimated reactor beam emitted from one of the horizontal channels of the ET-RR-1 reactor have been utilized in the present work. The distribution of the secondary gamma ray doses generated from the interaction of reactor neutrons of definite energy ranges has also been obtained for ilmenite-limonite concrete. The gamma doses were measured using {sup 7}LiF Teflon disc TL dosimeters. A semiempirical formula was derived to calculate total gamma dose distributions for bare, cadmium filtered and B{sub 4}C filtered reactor beams at different thickness along the beam axis in ordinary concrete, with density 2.3 g cm{sup -3}, using the corresponding measured value in ilmenite-limonite concrete. Good agreement has been achieved between the values of the total gamma doses and those calculated using the derived empirical formula. Isodose curves were constructed for both the total gamma-ray doses and the secondary gamma-ray doses shields together with the corresponding values for ordinary concrete shields. The thickness of ilmenite-limonite concrete required to attenuate the total gamma dose intensity to a certain factor is approximately 94% of the thickness when the shield is made of ordinary concrete. (orig./HP).

  13. 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.

  14. {sup 99m}Tc Auger electrons - Analysis on the effects of low absorbed doses by computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Adriana Alexandre S., E-mail: adriana_tavares@msn.co [Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Dr. Roberto Frias, S/N, 4200-465 Porto (Portugal); Tavares, Joao Manuel R.S., E-mail: tavares@fe.up.p [Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Dr. Roberto Frias, S/N, 4200-465 Porto (Portugal)

    2011-03-15

    We describe here the use of computational methods for evaluation of the low dose effects on human fibroblasts after irradiation with Technetium-99m ({sup 99m}Tc) Auger electrons. The results suggest a parabolic relationship between the irradiation of fibroblasts with {sup 99m}Tc Auger electrons and the total absorbed dose. Additionally, the results on very low absorbed doses may be explained by the bystander effect, which has been implicated on the cell's effects at low doses. Further in vitro evaluation will be worthwhile to clarify these findings.

  15. Dose-rate dependence of epitaxial diodes response for gamma dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, J.A.C.; Santos, T.C. dos; Barbosa, R.F.; Pascoalino, K.C.S.; 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: In this work, we present the preliminary results about the evaluation of dose-rate influence on the response of rad-hard epitaxial (EPI) diodes for on-line gamma-ray dosimetry using Co-60 irradiators. The diodes used were processed at University of Hamburg on n-type 75 micrometer thick epitaxial silicon layer (nominal resistivity of 69 Ohm.cm) grown on a highly doped n-type 300 micrometer thick Czochralski (Cz) silicon substrate. Two samples of EPI diodes were investigated: EPI-08 and EPI-10 - both non-irradiated previously. These devices, with 5mm x 5mm active area, were housed in a PMMA probe and connected, in a photovoltaic mode, to a Keithley 617 electrometer. The EPI-10 device irradiation was performed in the Radiation Technology Center at IPEN-CNEN/SP using a Co-60 irradiator (Gammacell 220 - Nordion) which delivers a dose rate of 2.16 kGy/h, while the EPI-08 device irradiation was performed in Nuclear Energy Department at UFPE/PE using the same model Co-60 irradiator, but with a dose-rate of 7.47 kGy/h. During the irradiation, the devices photocurrents were monitored as a function of the exposure time. The diodes were irradiated at room temperature. The dose-response curves of the EPI diodes were achieved through the integration of the current signals as a function of the exposure time. The normalized current signals as a function of the dose evidenced a decrease of about 60 percent from the initial current for the first 100 kGy dose received. After 500 kGy of exposure, the current signals stabilize (ou maintain stable). The dose-response curves behave as a second order polynomial fit, with correlation coefficients of about 0.99991 and 0.99995, respectively to EPI-10 and EPI-08 diodes. The preliminary results obtained evinced that the EPI diodes response are not dose-rate dependent within the range of 2.16 kGy/h up to 7.47 kGy/h. On the other hand, the devices studied are tolerant to radiation damages for total absorbed doses of approximately 550

  16. Measurements of the attenuation of neutron and gamma doses in ordinary and ilmenite concrete shields

    Energy Technology Data Exchange (ETDEWEB)

    Megahid, R.M.; Makarious, A.S.; El-Kolaly, M.A. (Atomic Energy Establishment, Inshas (Egypt). Reactor and Neutron Physics Dept.)

    1980-01-01

    Measurements have been carried out to study the attenuation of neutron and gamma-doses in ordinary and ilmenite concrete shields of densities 2.3 and 4.6 gt. cm/sup -3/ respectively. The attenuation of thermal neutron doses emitted directly from the reactor core and the secondary gamma doses produced from the absorption of these neutrons were evaluated. Measurements were performed using a reactor beam from one of the horizontal channels of the ET-RR-1 reactor. The neutron and gamma doses were monitored be means of Li/sub 2/ B/sub 4/ O/sub 7/: Mn and liF-7 teflon thermoluminescent dosimeters. The measured data give the value of the relative intensities between neutron and gamma doses obtained in these two types of concrete. The contribution of thermal neutrons emitted directly from the reactor core and the secondary gamma from the radiative capture of these neutrons were evaluated.

  17. Evaluation of dose distributions in gamma chamber using glass plate detector

    Directory of Open Access Journals (Sweden)

    Narayan Pradeep

    2008-01-01

    Full Text Available A commercial glass plate of thickness 1.75 mm has been utilized for evaluation of dose distributions inside the irradiation volume of gamma chamber using optical densitometry technique. The glass plate showed linear response in the dose range 0.10 Kilo Gray (kGy to 10 kGy of cobalt-60 gamma radiation with optical sensitivity 0.04 Optical Density (OD /kGy. The change in the optical density at each identified spatial dose matrix on the glass plate in relation to the position in the irradiation volume has been presented as dose distributions inside the gamma chamber. The optical density changes have been graphically plotted in the form of surface diagram of color washes for different percentage dose rate levels as isodose distributions in gamma chamber. The variation in dose distribution inside the gamma chamber unit, GC 900, BRIT India make, using this technique has been observed within ± 15%. This technique can be used for routine quality assurances and dose distribution validation of any gamma chamber during commissioning and source replacement. The application of commercial glass plate for dose mapping in gamma chambers has been found very promising due to its wider dose linearity, quick measurement, and lesser expertise requirement in application of the technique.

  18. Detection and quantification of (223)Ra uptake in bone metastases of patients with castration resistant prostate carcinoma, with the aim of determining the absorbed dose in the metastases.

    Science.gov (United States)

    Mínguez, P; Gómez de Iturriaga, A; Fernández, I L; Rodeño, E

    2017-06-20

    To obtain the necessary acquisition and calibration parameters in order to evaluate the possibility of detecting and quantifying (223)Ra uptake in bone metastases of patients treated for castration resistant prostate carcinoma. Furthermore, in the cases in which the activity can be quantified, to determine the absorbed dose. Acquisitions from a Petri dish filled with (223)Ra were performed in the gamma camera. Monte Carlo simulations were also performed to study the partial volume effect. Formulae to obtain the detection and quantification limits of (223)Ra uptake were applied to planar images of two patients 7 days post-administration of 55kBq/kg of (223)Ra. In order to locate the lesions in advance, whole-body scans and SPECT/CT images were acquired after injecting (99m)Tc-HDP. The optimal energy window was found to be at 82keV with a medium-energy collimator MEGP. Of the lesions found in the patients, only those that had been detected in both the AP and PA projections could be quantified. These lesions were those which had shown a higher (99m)Tc-HDP uptake. The estimated values of absorbed doses ranged between 0.7Gy and 7.8Gy. Of the lesions that can be detected, it is not possible to quantify the activity uptake in some of them, which means that the absorbed dose cannot be determined either. This does not mean that the absorbed dose in these lesions can be regarded as negligible. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

  19. 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.

  20. 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.

  1. Dosimetric effect by the low-dose threshold levels in gamma analysis on VMAT QA

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ji Hye; Kim, Min Joo; Park, So Hyun; Lee, Seu Ran; Lee, Min Young; Suh, Tae Suk [Dept. of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Lee, Dong Soo [Dept. of Radiation Oncology, Uijeongbu St. Mary' s Hospital, Uijeongbu (Korea, Republic of)

    2015-10-15

    Based on a survey by Nelms and Simon, more than 70% of institutions use a low-dose threshold between 0% and 10% for gamma analysis. However, there are no clinical data to quantitatively demonstrate the impact of the low-dose threshold on the gamma index. Therefore, we performed a gamma analysis with low-dose thresholds of 0%, 5%, 10%, and 15% according to both global and local normalization and different acceptance criteria: 3%/3 mm, 2%/2 mm, and 1%/1 mm. Applying low-dose threshold in the global normalization does not have critical effect to judge patient-specific QA results.

  2. Assessment of the absorbed dose to organs from bone mineral density scan by using TLDS and the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    Karimian Alireza

    2014-01-01

    Full Text Available Nowadays, dual energy X-ray absorptiometry is used in bone mineral density systems to assess the amount of osteoporosis. The purpose of this research is to evaluate patient organ doses from dual X-ray absorptiometry by thermoluminescence dosimeters chips and Monte Carlo method. To achieve this goal, in the first step, the surface dose of the cervix, kidney, abdomen region, and thyroid were measured by using TLD-GR 200 at various organ locations. Then, to evaluate the absorbed dose by simulation, the BMD system, patient's body, X-ray source and radiosensitive tissues were simulated by the Monte Carlo method. The results showed, for the spine (left femur bone mineral density scan by using thermoluminescence dosimeters, the absorbed doses of the cervix and kidney were 4.5 (5.64 and 162.17 (3.99(mGy, respectively. For spine (left femur bone mineral density scan in simulation, the absorbed doses of the cervix and kidney were 4.19 (5.88 and 175 (3.68(mGy, respectively. The data obtained showed that the absorbed dose of the kidney in the spine scan is noticeable. Furthermore, because of the small relative difference between the simulation and experimental results, the radiation absorbed dose may be assessed by simulation and software, especially for internal organs, and at different depths of otherwise inaccessible organs which is not possible in experiments.

  3. Equivalence of cell survival data for radiation dose and thermal dose in ablative treatments: analysis applied to essential tremor thalamotomy by focused ultrasound and gamma knife.

    Science.gov (United States)

    Schlesinger, D; Lee, M; Ter Haar, G; Sela, B; Eames, M; Snell, J; Kassell, N; Sheehan, J; Larner, J M; Aubry, J-F

    2017-01-31

    Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to measure the biological effect of each procedure. Survival curves for both thermal and radiation doses have been extracted from previously published data for three different cell types. Fits of these curves were used to convert both thermal and radiation dose into the same quantified biological effect: fraction of surviving cells. They have also been used to generate and compare survival profiles from the only indication for which clinical data are available for both focused ultrasound (FUS) thermal ablation and radiation ablation: essential tremor thalamotomy. All cell types could be fitted with coefficients of determination greater than 0.992. As an illustration, survival profiles of clinical thalamotomies performed by radiosurgery and FUS are plotted on a same graph for the same metric: fraction of surviving cells. FUS and Gamma Knife have the potential to be used in combination to deliver a more effective treatment (for example, FUS may be used to debulk the main tumour mass, and radiation to treat the surrounding tumour bed). In this case, a model which compares thermal and radiation treatments is valuable in order to adjust the dose between the two.

  4. Novel Radiobiological Gamma Index for Evaluation of 3-Dimensional Predicted Dose Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Sumida, Iori, E-mail: sumida@radonc.med.osaka-u.ac.jp [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Yamaguchi, Hajime; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yoshikawa, Nobuhiko; Yamada, Yuji [Department of Radiation Oncology, NTT West Osaka Hospital, Osaka (Japan); Suzuki, Osamu; Seo, Yuji [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Isohashi, Fumiaki [Department of Radiation Oncology, NTT West Osaka Hospital, Osaka (Japan); Yoshioka, Yasuo [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Ogawa, Kazuhiko [Department of Radiation Oncology, NTT West Osaka Hospital, Osaka (Japan)

    2015-07-15

    Purpose: To propose a gamma index-based dose evaluation index that integrates the radiobiological parameters of tumor control (TCP) and normal tissue complication probabilities (NTCP). Methods and Materials: Fifteen prostate and head and neck (H&N) cancer patients received intensity modulated radiation therapy. Before treatment, patient-specific quality assurance was conducted via beam-by-beam analysis, and beam-specific dose error distributions were generated. The predicted 3-dimensional (3D) dose distribution was calculated by back-projection of relative dose error distribution per beam. A 3D gamma analysis of different organs (prostate: clinical [CTV] and planned target volumes [PTV], rectum, bladder, femoral heads; H&N: gross tumor volume [GTV], CTV, spinal cord, brain stem, both parotids) was performed using predicted and planned dose distributions under 2%/2 mm tolerance and physical gamma passing rate was calculated. TCP and NTCP values were calculated for voxels with physical gamma indices (PGI) >1. We propose a new radiobiological gamma index (RGI) to quantify the radiobiological effects of TCP and NTCP and calculate radiobiological gamma passing rates. Results: The mean RGI gamma passing rates for prostate cases were significantly different compared with those of PGI (P<.03–.001). The mean RGI gamma passing rates for H&N cases (except for GTV) were significantly different compared with those of PGI (P<.001). Differences in gamma passing rates between PGI and RGI were due to dose differences between the planned and predicted dose distributions. Radiobiological gamma distribution was visualized to identify areas where the dose was radiobiologically important. Conclusions: RGI was proposed to integrate radiobiological effects into PGI. This index would assist physicians and medical physicists not only in physical evaluations of treatment delivery accuracy, but also in clinical evaluations of predicted dose distribution.

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, J.C.

    1991-01-01

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

  7. Verification of absorbed dose to the lung SBRT treatments; Verificacion de dosis absorbida en los tratamientos de SBRT de pulmon

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Gonzalez, J.; Modolell Farre, I.

    2011-07-01

    The hypo fractionated stereotactic radiotherapy technique applied to the lung, also known as lung SBRT is a technique that small volumes irradiated to high doses using photon beams, usually not coplanar, with energies of 6 and 15 MV. Because of the uncertainties associated with the small field dosimetry calculation in heterogeneous media comes the need to verify the absorbed dose.

  8. Assessment of Environmental Gamma Radiation Dose Rate in Ardabil and Sarein in 2009

    Directory of Open Access Journals (Sweden)

    M Alighadri

    2011-10-01

    Full Text Available Background and Objectives: Gamma rays, the most energetic photons within the any other wave in the electromagnetic spectrum, pose enough energy to form charged particles and adversely affect human health. Provided that the external exposure of human beings to natural environmental gamma radiation normally exceeds that from all man-made sources combined, environmental gamma dose rate and corresponding annual effective dose were determined in the cities of Ardabil and Sar Ein.Materials and Methods: Outdoor environmental gamma dose rates were measured using an Ion Chamber Survey Meter in 48 selected locations (one in city center and the remaining in cardinal and ordinal directions in Ardabil and Sar Ein. Ten more locations were monitored along the hot springs effluent in Sar Ein. Measurements of gamma radiation dose rate were performed at 20 and 100 cm above the ground for a period of one hour.Results: Average outdoor environmental gamma dose rate were determined as 265, 219, and 208  for Ardabil, Sar Ein, and along the hot spring effluent, respectively. The annual affective dose for Ardabil and Sar Ein residents were estimated to be 1.45 and 1.39 mSv, respectively.Conclusion: Calculated annual effective dose of 1.49 and 1.35 are appreciably higher than the population weighted average exposure to environmental gamma radiation worldwide and that analysis of soil content to different radionuclide is suggested.

  9. Irradiation with low-dose gamma ray enhances tolerance to heat stress in Arabidopsis seedlings.

    Science.gov (United States)

    Zhang, Liang; Zheng, Fengxia; Qi, Wencai; Wang, Tianqi; Ma, Lingyu; Qiu, Zongbo; Li, Jingyuan

    2016-06-01

    Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings.

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

    Directory of Open Access Journals (Sweden)

    Shyam Mohan Srinivas

    2014-10-01

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

  12. Measurement of the absorbed dose distribution near an 192Ir intravascular brachytherapy seed using a high-spatial-resolution gel dosimetry system

    Science.gov (United States)

    Massillon-JL, G.; Minniti, R.; Mitch, M. G.; Soares, C. G.

    2012-06-01

    The absorbed dose distribution at sub-millimeter distances from the Best single 192Ir intravascular brachytherapy seed was measured using a high-spatial-resolution gel dosimetry system. Two gel phantoms from the same batch were used; one for the seed irradiation and one for calibration. Since the response of this gel is energy independent for photons between 20 and 1250 keV, the gel was calibrated using a narrowly collimated 60Co gamma-ray beam (cross-sectional area ˜1 cm2). A small format laser computed tomography scanner was used to acquire the data. The measurements were carried out with a spatial resolution of 100 µm in all dimensions. The seed was calibrated at NIST in terms of air-kerma strength. The absorbed dose rate as well as the radial dose function, gL(r), was measured for radial distances between 0.6 and 12.6 mm from the seed center. The dose rate constant was measured, yielding a value of Λ = (1.122 ± 0.032) cGy h-1 U-1, which agrees with published data within the measurement uncertainty. For distances between 0.6 and 1.5 mm, gL(r) decreases from a maximum value of 1.06 down to 1.00; between 1.5 and 6.7 mm, an enhancement is clearly observed with a maximum value around 1.24 and beyond 6.7 mm, gL(r) has an approximately constant value around 1.0, which suggests that this seed can be considered as a point source only at distances larger than 6.7 mm. This latter observation agrees with data for the same seed reported previously using Gafchromic film MD-55-2. Additionally, published Monte Carlo (MC) calculations have predicted the observed behavior of the radial dose function resulting from the absorbed dose contributions of beta particles and electrons emitted by the 192Ir seed. Nonetheless, in the enhancement region, MC underestimates the dose by approximately 20%. This work suggests that beta particles and electrons emitted from the seed make a significant contribution to the total absorbed dose delivered at distances near the seed center (less

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-10-21

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

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

    CERN Document Server

    Pisharody, M; Berkvens, P; Colomp, P

    2000-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo deAlmeida

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

  18. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

    Science.gov (United States)

    Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

    2015-01-01

    Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. PMID:26437425

  19. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico.

    Science.gov (United States)

    Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

    2015-09-30

    Determining ionizing radiation in a geographic area serves to assess its effects on a population's health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h(-1). At the same sites, 48 soil samples were taken to obtain the activity concentrations of (226)Ra, (232)Th and (40)K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h(-1). Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg(-1), for (226)Ra, (232)Th and (40)K, respectively. From the analysis, the spatial distribution of (232)Th, (226)Ra and (40)K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

  20. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

    Directory of Open Access Journals (Sweden)

    Sergio Luevano-Gurrola

    2015-09-01

    Full Text Available Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

  1. A simple method for conversion of airborne gamma-ray spectra to ground level doses

    DEFF Research Database (Denmark)

    Korsbech, Uffe C C; Bargholz, Kim

    1996-01-01

    A new and simple method for conversion of airborne NaI(Tl) gamma-ray spectra to dose rates at ground level has been developed. By weighting the channel count rates with the channel numbers a spectrum dose index (SDI) is calculated for each spectrum. Ground level dose rates then are determined...

  2. 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)

  3. Exposure of luminous marine bacteria to low-dose gamma-radiation.

    Science.gov (United States)

    Kudryasheva, N S; Petrova, A S; Dementyev, D V; Bondar, A A

    2017-04-01

    The study addresses biological effects of low-dose gamma-radiation. Radioactive (137)Cs-containing particles were used as model sources of gamma-radiation. Luminous marine bacterium Photobacterium phosphoreum was used as a bioassay with the bioluminescent intensity as the physiological parameter tested. To investigate the sensitivity of the bacteria to the low-dose gamma-radiation exposure (≤250 mGy), the irradiation conditions were varied as follows: bioluminescence intensity was measured at 5, 10, and 20°С for 175, 100, and 47 h, respectively, at different dose rates (up to 4100 μGy/h). There was no noticeable effect of gamma-radiation at 5 and 10°С, while the 20°С exposure revealed authentic bioluminescence inhibition. The 20°С results of gamma-radiation exposure were compared to those for low-dose alpha- and beta-radiation exposures studied previously under comparable experimental conditions. In contrast to ionizing radiation of alpha and beta types, gamma-emission did not initiate bacterial bioluminescence activation (adaptive response). As with alpha- and beta-radiation, gamma-emission did not demonstrate monotonic dose-effect dependencies; the bioluminescence inhibition efficiency was found to be related to the exposure time, while no dose rate dependence was found. The sequence analysis of 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose gamma radiation. The exposure time that caused 50% bioluminescence inhibition was suggested as a test parameter for radiotoxicity evaluation under conditions of chronic low-dose gamma irradiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Dose-dependent hepatic transcriptional responses in Atlantic salmon (Salmo salar) exposed to sublethal doses of gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Song, You, E-mail: you.song@niva.no [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo (Norway); Salbu, Brit; Teien, Hans-Christian; Heier, Lene Sørlie [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Rosseland, Bjørn Olav [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Norwegian University of Life Sciences (NMBU), Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432 Ås (Norway); Tollefsen, Knut Erik [Norwegian University of Life Sciences (NMBU), Faculty of Environmental Science and Technology, Department of Environmental Sciences (IMV), Centre for Environmental Radioactivity - CERAD, P.O. Box 5003, N-1432 Ås (Norway); Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo (Norway)

    2014-11-15

    Highlights: • First study on early stress responses in salmon exposed to low-dose gamma radiation. • Dramatic dose-dependent transcriptional responses characterized. • Multiple modes of action proposed for gamma radiation. - Abstract: Due to the production of free radicals, gamma radiation may pose a hazard to living organisms. The high-dose radiation effects have been extensively studied, whereas the ecotoxicity data on low-dose gamma radiation is still limited. The present study was therefore performed using Atlantic salmon (Salmo salar) to characterize effects of low-dose (15, 70 and 280 mGy) gamma radiation after short-term (48 h) exposure. Global transcriptional changes were studied using a combination of high-density oligonucleotide microarrays and quantitative real-time reverse transcription polymerase chain reaction (qPCR). Differentially expressed genes (DEGs; in this article the phrase gene expression is taken as a synonym of gene transcription, although it is acknowledged that gene expression can also be regulated, e.g., at protein stability and translational level) were determined and linked to their biological meanings predicted using both Gene Ontology (GO) and mammalian ortholog-based functional analyses. The plasma glucose level was also measured as a general stress biomarker at the organism level. Results from the microarray analysis revealed a dose-dependent pattern of global transcriptional responses, with 222, 495 and 909 DEGs regulated by 15, 70 and 280 mGy gamma radiation, respectively. Among these DEGs, only 34 were commonly regulated by all radiation doses, whereas the majority of differences were dose-specific. No GO functions were identified at low or medium doses, but repression of DEGs associated with GO functions such as DNA replication, cell cycle regulation and response to reactive oxygen species (ROS) were observed after 280 mGy gamma exposure. Ortholog-based toxicity pathway analysis further showed that 15 mGy radiation

  5. Uncertainty analysis in the determination of absorbed dose in water by Fricke chemical dosimetry; Analise das incertezas na determinacao da dose absorvida na agua por dosimetria quimica Fricke

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Fabia; Aguirre, Eder Aguirre, E-mail: fabiavasco@hotmail.com, E-mail: ederuni01@gmail.com [Fundacao do Cancer, Rio de Janeiro, RJ (Brazil); Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2016-07-01

    This work studies the calculations of uncertainties and the level of confidence that involves the process for obtaining the dose absorbed in water using the method of Fricke dosimetry, developed at Laboratorio de Ciencias Radiologicas (LCR). Measurements of absorbance of samples Fricke, irradiated and non-irradiated is going to use in order to calculate the respective sensitivity coefficients, along with the expressions of the calculation of Fricke dose and the absorbed dose in water. Those expressions are used for calculating the others sensitivity coefficients from the input variable. It is going to use the combined uncertainty and the expanded uncertainty, with a level of confidence of 95.45%, in order to report the uncertainties of the measurement. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-15

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

  7. Effect of gamma-dose rate and total dose interrelation on the polymeric hydrogel: A novel injectable male contraceptive

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Pradeep K. [School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721302 (India); Department of Management Science, U.P. Technical University, Lucknow 226021 (India); Jha, Rakhi [School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721302 (India); Toxicology Laboratory, Department of Zoology, Ch. C.S. University, Meerut 200005 (India); Gupta, B.L. [CH3/56 Kendriya Vihar, Kharghar, Sector-11, Navi Mumbai-410 210 (India); Guha, Sujoy K., E-mail: guha_sk@yahoo.co [School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721302 (India)

    2010-05-15

    Functional necessity to use a particular range of dose rate and total dose of gamma-initiated polymerization to manufacture a novel polymeric hydrogel RISUG (reversible inhibition of sperm under guidance) made of styrene maleic anhydride (SMA) dissolved in dimethyl sulphoxide (DMSO), for its broad biomedical application explores new dimension of research. The present work involves 16 irradiated samples. They were tested by fourier transform infrared spectroscopy, matrix assisted laser desorption/ionization-TOF, field emission scanning electron microscopy, high resolution transmission electron microscopy, etc. to see the interrelation effect of gamma dose rates (8.25, 17.29, 20.01 and 25.00 Gy/min) and four sets of doses (1.8, 2.0, 2.2 and 2.4 kGy) on the molecular weight, molecular weight distribution and porosity analysis of the biopolymeric drug RISUG. The results of randomized experiment indicated that a range of 18-24 Gy/min gamma-dose rate and 2.0-2.4 kGy gamma-total doses is suitable for the desirable in vivo performance of the contraceptive copolymer.

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

    Science.gov (United States)

    Nunes, Josane C.

    1991-02-01

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

  9. Criticality prompt gamma and neutron dose equations validated by Monte Carlo analyses and compared to known criticality accident doses

    Science.gov (United States)

    Hochhalter, Eugene

    The United States (US) Department of Energy [DOE] and the Nuclear Regulatory Commission [NRC] have provided the nuclear industry with requirements, goals, and objectives for the preparation of safety analysis and the finalization of that safety analysis in the form of a documented safety analysis (DSA) and technical safety requirements (TSRs). The deterministic guidance provided by the NRC in Regulatory Guide (RG) 3.33 for calculating the prompt gamma and neutron doses from a criticality has a number of potential issues associated with the semi-empirical equations, which make these equations potentially out dated. The NRC guidance for estimating the prompt gamma and neutron doses to a facility worker due to an accidental criticality was withdrawn without newer deterministic guidance being issued. This research project determined the original basis for the RG prompt gamma and neutron equations, evaluated the potential issues associated with the RG 3.33 prompt gamma and neutron equations, and modified the RG 3.33 point source prompt gamma and neutron equations to calculate the doses for the selected set of criticality accidents. The criticality accidents addressed by this dissertation include: 1. U-235, Pu-239, and Pu-241 point source criticality, 2. U-235, Pu-239, and Pu-241 sphere source criticality, 3. Uranyl nitrate and plutonium nitrate solutions in a cylindrical process vessel and 4. Low level waste in 55-gallon and 30-gallon drums. The prompt gamma and neutron equation doses (RG 3.33/3.34/3.35) are compared to actual nuclear industry criticality accident worker doses to assess the conservatism of the RG equations. Finally, the RG 3.33 prompt gamma and neutron dose equations are compared to MCNP5 results to investigate consistency with respect to the modified prompt gamma and neutron dose equations and the representative dose estimates for each of the criticality configurations (point source, spherical source, and cylindrical source). Knowledge and accurate

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

    Science.gov (United States)

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

    2016-11-01

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

  11. 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.

  12. A gamma dose distribution evaluation technique using the k-d tree for nearest neighbor searching.

    Science.gov (United States)

    Yuan, Jiankui; Chen, Weimin

    2010-09-01

    The authors propose an algorithm based on the k-d tree for nearest neighbor searching to improve the gamma calculation time for 2D and 3D dose distributions. The gamma calculation method has been widely used for comparisons of dose distributions in clinical treatment plans and quality assurances. By specifying the acceptable dose and distance-to-agreement criteria, the method provides quantitative measurement of the agreement between the reference and evaluation dose distributions. The gamma value indicates the acceptability. In regions where gamma nearest neighbor can be an O (log N) operation with a k-d tree, where N is the total number of the dose points, the authors propose an algorithm based on the k-d tree for the gamma evaluation in this work. In the experiment, the authors found that the average k-d tree construction time per reference point is O (log N), while the nearest neighbor searching time per evaluation point is proportional to O (N(1/k), where k is between 2 and 3 for two-dimensional and three-dimensional dose distributions, respectively. Comparing with other algorithms such as exhaustive search and sorted list O (N), the k-d tree algorithm for gamma evaluation is much more efficient.

  13. Committed dose assessment based on background outdoor gamma exposure in Chihuahua City, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Luevano G, S.; Perez T, A.; Pinedo A, C.; Renteria V, M. [Universidad Autonoma de Chihuahua, Facultad de Zootecnia y Ecologia, Perif. Francisco R. Almada Km 1, 31415 Chihuahua, Chih. (Mexico); Carrillo F, J.; Montero C, M. E., E-mail: mrenteria@uach.mx [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes 120, 31136 Chihuahua, Chih. (Mexico)

    2015-10-15

    Full text: Determining ionizing radiation in a geographic area serves to assess its effects on populations health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the committed dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, annual effective dose, and the lifetime cancer risk, 48 sampling points were randomly selected along the Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Muller counter. At the same sites, 48 soil samples were taken to obtain the activity concentrations of {sup 226}Ra, {sup 232}Th, {sup 40}K and their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Outdoor gamma dose rates ranged from 56 to 193 n Gy h{sup -1}. Results indicated that lifetime effective dose to inhabitants of Chihuahua City is in average of 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of activity concentrations in soil were 51.8, 73.1, and 1096.5 Bq kg{sup -1}, of {sup 226}Ra, {sup 232}Th and {sup 40}K, respectively. From the analysis of the spatial distribution of {sup 232}Th, {sup 226}Ra, and {sup 40}K is to north, to north-center, and to south of city, respectively. In conclusion, natural background gamma dose received by inhabitants of Chihuahua City is high and mainly due to geological characteristics of the zone. (Author)

  14. 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.

  15. Low doses effects and gamma radiations low dose rates; Les effets des faibles doses et des faibles debits de doses de rayons gamma

    Energy Technology Data Exchange (ETDEWEB)

    Averbeck, D. [Institut Curie, CNRS UMR 2027, 75 - Paris (France)

    1999-07-01

    This expose wishes for bringing some definitions and base facts relative to the problematics of low doses effects and low dose rates effects. It shows some already used methods and some actual experimental approaches by focusing on the effects of ionizing radiations with a low linear energy transfer. (N.C.)

  16. Absorbed organ and effective doses from digital intra-oral and panoramic radiography applying the ICRP 103 recommendations for effective dose estimations.

    Science.gov (United States)

    Granlund, Christina; Thilander-Klang, Anne; Ylhan, Betȕl; Lofthag-Hansen, Sara; Ekestubbe, Annika

    2016-10-01

    During dental radiography, the salivary and thyroid glands are at radiation risk. In 2007, the International Commission on Radiological Protection (ICRP) updated the methodology for determining the effective dose, and the salivary glands were assigned tissue-specific weighting factors for the first time. The aims of this study were to determine the absorbed dose to the organs and to calculate, applying the ICRP publication 103 tissue-weighting factors, the effective doses delivered during digital intraoral and panoramic radiography. Thermoluminescent dosemeter measurements were performed on an anthropomorphic head and neck phantom. The organ-absorbed doses were measured at 30 locations, representing different radiosensitive organs in the head and neck, and the effective dose was calculated according to the ICRP recommendations. The salivary glands and the oral mucosa received the highest absorbed doses from both intraoral and panoramic radiography. The effective dose from a full-mouth intraoral examination was 15 μSv and for panoramic radiography, the effective dose was in the range of 19-75 μSv, depending on the panoramic equipment used. The effective dose from a full-mouth intraoral examination is lower and that from panoramic radiography is higher than previously reported. Clinicians should be aware of the higher effective dose delivered during panoramic radiography and the risk-benefit profile of this technique must be assessed for the individual patient. The effective dose of radiation from panoramic radiography is higher than previously reported and there is large variability in the delivered radiation dosage among the different types of equipment used.

  17. Gamma-radiation-induced corrosion of aluminum alloy: low dose effect

    Science.gov (United States)

    Kanjana, K.; Ampornrat, P.; Channuie, J.

    2017-06-01

    Gamma-radiation-induced corrosion of aluminium alloy 6061 (AA6061) immersed in demineralized water was studied at radiation dose up to 206 kGy using a Co-60 gamma radiation source. The surface morphology and chemical composition of the oxide produced on the post-irradiated samples were investigated using SEM-EDS. The electrochemical corrosion potentials (Ecorr ) of the post-irradiated samples were measured. The corrosion behavior of AA6061 appeared to be dose dependent under the experimental conditions. A dramatic change in surface morphology was observed in the samples exposed to gamma radiation at 206 kGy. At this radiation dose the aluminium oxide scale developed can be clearly seen. The results from electrochemical corrosion tests have shown that the corrosion potentials (Ecorr ) can be undoubtedly decreased by gamma irradiation, giving corrosion rate of 7 × 10-4 mm/yr.

  18. 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

  19. 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)

  20. Preliminary survey of outdoor gamma dose rates in Lesvos Island (Greece).

    Science.gov (United States)

    Petalas, Anastasios B; Vogiannis, Efstratios; Nikolopoulos, Dimitrios; Halvadakis, Constantinos P

    2005-01-01

    This study reports the first attempt to record the radioactive background due to gamma radiation in Lesvos Island (Greece). The study reports the results from 335 outdoor total gamma effective dose rate measurements conducted using GPS navigation and a Geiger-Muller detector (Bicron, Micro Sievert) on the whole surface of the island together with a digital map produced by appropriate mapping GIS programme. The study also reports the measurements of outdoor gamma dose rates due to the 238U, 232Th and 40K radionuclides as estimated via in situ gamma-ray spectrometry measurements performed at 26 sites using a 3 x 3 inch NaI (thallium activated) portable detector. The results from the outdoor total gamma effective dose rates range between 0.0023 and 0.28 microSv h(-1). The highest outdoor total gamma effective dose rates (0.013-0.28 microSv h(-1)) were detected in the northeastern part of the island and the intermediate rates (0.066-0.13 microSv h(-1)) in the central region. The outdoor gamma dose rates due to 238U, 232Th and 40K radionuclides range between 1.7 +/- 0.8 and 154 +/- 7 nGy h(-1) with an average of 86 +/- 6 nGy h(-1). The average contribution of each of the examined radionuclides (238U, 232Th and 40K) to the total gamma dose rate was found to be equal to 12 +/- 4% for 238U, 58 +/- 6% for 232Th and 29 +/- 7% for 40K, respectively.

  1. 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.

  2. 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)

  3. Effect of statistical fluctuation in Monte Carlo based photon beam dose calculation on gamma index evaluation.

    Science.gov (United States)

    Graves, Yan Jiang; Jia, Xun; Jiang, Steve B

    2013-03-21

    The γ-index test has been commonly adopted to quantify the degree of agreement between a reference dose distribution and an evaluation dose distribution. Monte Carlo (MC) simulation has been widely used for the radiotherapy dose calculation for both clinical and research purposes. The goal of this work is to investigate both theoretically and experimentally the impact of the MC statistical fluctuation on the γ-index test when the fluctuation exists in the reference, the evaluation, or both dose distributions. To the first order approximation, we theoretically demonstrated in a simplified model that the statistical fluctuation tends to overestimate γ-index values when existing in the reference dose distribution and underestimate γ-index values when existing in the evaluation dose distribution given the original γ-index is relatively large for the statistical fluctuation. Our numerical experiments using realistic clinical photon radiation therapy cases have shown that (1) when performing a γ-index test between an MC reference dose and a non-MC evaluation dose, the average γ-index is overestimated and the gamma passing rate decreases with the increase of the statistical noise level in the reference dose; (2) when performing a γ-index test between a non-MC reference dose and an MC evaluation dose, the average γ-index is underestimated when they are within the clinically relevant range and the gamma passing rate increases with the increase of the statistical noise level in the evaluation dose; (3) when performing a γ-index test between an MC reference dose and an MC evaluation dose, the gamma passing rate is overestimated due to the statistical noise in the evaluation dose and underestimated due to the statistical noise in the reference dose. We conclude that the γ-index test should be used with caution when comparing dose distributions computed with MC simulation.

  4. Angular and energy dependence of radiation protection monitors to the quantity ambient dose equivalent for gamma radiation;Dependencia angular e energetica de monitores de radioprotecao para medidas de equivalente de dose ambiental para radiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Nonato, Fernanda B.C.; Carvalho, Valdir S.; Diniz, Raphael E.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    In Brazil, most of the equipment used for monitoring area is just used in the quantities exposure and absorbed dose, with the need of adjustment to the ambient dose equivalent, H{sup *}(10). In this work, 19 Geiger-Mueller detectors and 7 ionization chambers were calibrated in the Calibration Laboratory of the Instituto de Pesquisas Energeticas Nucleares, IPEN. The energy dependence of these radiation detectors was studied for gamma radiation ({sup 137}Cs e {sup 60}Co) and the angular dependence, for {sup 137}Cs radiation. (author)

  5. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators.

    Science.gov (United States)

    Rodrigues, Ary A; Vieira, Jose M; Hamada, Margarida M

    2010-01-01

    A 1 cm(3) cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a (60)Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  6. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Ary A. [Universidade Estadual de Londrina-Depto de Fisica, Rodovia Celso Garcia Cid, km 38, 086051-990 Londrina (Brazil); Vieira, Jose M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Hamada, Margarida M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900 Sao Paulo (Brazil)], E-mail: mmhamada@ipen.br

    2010-04-15

    A 1 cm{sup 3} cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a {sup 60}Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  7. Population dose from indoor gamma exposure in the dwellings around Kudankulam nuclear power plant.

    Science.gov (United States)

    Brahmanandhan, G M; Selvasekarapandian, S; Malathi, J; Khanna, D; Jose, M T; Meenakshisundaram, V

    2008-01-01

    To assess the population dose due to the natural background radiation around the upcoming Kudankulam nuclear power plant, a systematic investigation has been carried out by measuring the indoor gamma dose. In total, 159 dwellings have been selected around the Kudankulam nuclear power plant area i.e. in Radhapuram and Nanguneri taluk (sub-districts) for the measurement. The geometric mean value of indoor gamma dose rate is 305 +/- 48 nGy h(-1) and 273 +/- 50 nGy h(-1) in Radhapuram and Nanguneri taluks (sub-districts), respectively. The annual effective dose due to indoor gamma radiation to the population has been found to be 1.5 mSv and 1.36 mSv in Radhapuram and Nanguneri taluks, respectively.

  8. 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.

  9. Effects of high dose rate gamma radiation on survival and reproduction of Biomphalaria glabrata

    Energy Technology Data Exchange (ETDEWEB)

    Cantinha, Rebeca S.; Nakano, Eliana [Instituto Butantan, Sao Paulo, SP (Brazil). Lab. de Parasitologia], e-mail: rebecanuclear@gmail.com, e-mail: eliananakano@butantan.gov.br; Borrely, Sueli I. [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Centro de Tecnologia das Radiacoes], e-mail: sborrely@ipen.br; Amaral, Ademir; Melo, Ana M.M.A. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia (GERAR)], e-mail: amaral@ufpe.br; Silva, Luanna R.S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Biofisica e Radiobiologia. Lab. de Radiobiologia], e-mail: amdemelo@hotmail.com, e-mail: luannaribeiro_lua@hotmail.com

    2009-07-01

    Ionizing radiations are known as mutagenic agents, causing lethality and infertility. This characteristic has motivated its application on animal biological control. In this context, the freshwater snail Biomphalaria glabrata can be considered an excellent experimental model to study effects of ionizing radiations on lethality and reproduction. This work was designed to evaluate effects of {sup 60}Co gamma radiation at high dose rate (10.04 kGy/h) on B. glabrata. For this purpose, adult snails were selected and exposed to doses ranging from 20 to 100 Gy, with 10 Gy intervals; one group was kept as control. There was not effect of dose rate in the lethality of gamma radiation; the value of 64,3 Gy of LD{sub 50} obtained in our study was similar to that obtained by other authors with low dose rates. Nevertheless, our data suggest that there was a dose rate effect in the reproduction. On all dose levels, radiation improved the production of embryos for all exposed individuals. However, viability indexes were below 6% and, even 65 days after irradiation, fertility was not recovered. These results are not in agreement with other studies using low dose rates. Lethality was obtained in all groups irradiated, and the highest doses presented percentiles of dead animals above 50%. The results demonstrated that doses of 20 and 30 Gy were ideal for population control of B. glabrata. Further studies are needed; nevertheless, this research evidenced great potential of high dose rate gamma radiation on B. glabrata reproductive control. (author)

  10. 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.)

  11. Indoor terrestrial gamma dose rate mapping in France: a case study using two different geostatistical models.

    Science.gov (United States)

    Warnery, E; Ielsch, G; Lajaunie, C; Cale, E; Wackernagel, H; Debayle, C; Guillevic, J

    2015-01-01

    Terrestrial gamma dose rates show important spatial variations in France. Previous studies resulted in maps of arithmetic means of indoor terrestrial gamma dose rates by "departement" (French district). However, numerous areas could not be characterized due to the lack of data. The aim of our work was to obtain more precise estimates of the spatial variability of indoor terrestrial gamma dose rates in France by using a more recent and complete data base and geostatistics. The study was based on the exploitation of 97,595 measurements results distributed in 17,404 locations covering all of France. Measurements were done by the Institute for Radioprotection and Nuclear Safety (IRSN) using RPL (Radio Photo Luminescent) dosimeters, exposed during several months between years 2011 and 2012 in French dentist surgeries and veterinary clinics. The data used came from dosimeters which were not exposed to anthropic sources. After removing the cosmic rays contribution in order to study only the telluric gamma radiation, it was decided to work with the arithmetic means of the time-series measurements, weighted by the time-exposure of the dosimeters, for each location. The values varied between 13 and 349 nSv/h, with an arithmetic mean of 76 nSv/h. The observed statistical distribution of the gamma dose rates was skewed to the right. Firstly, ordinary kriging was performed in order to predict the gamma dose rate on cells of 1*1 km(2), all over the domain. The second step of the study was to use an auxiliary variable in estimates. The IRSN achieved in 2010 a classification of the French geological formations, characterizing their uranium potential on the bases of geology and local measurement results of rocks uranium content. This information is georeferenced in a map at the scale 1:1,000,000. The geological uranium potential (GUP) was classified in 5 qualitative categories. As telluric gamma rays mostly come from the progenies of the (238)Uranium series present in rocks, this

  12. Pathological consequences of chronic low daily dose gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Seed, T.M.; Miller, A.C.; Ramakrishnan, N. [Armed Forces Radiobiology Research Inst., Bethesda, MD (United States); Fritz, T.E.

    2000-07-01

    The quantitative relationships between the chronic radiation exposure parameters of dose-rate and total dose in relation to associated health risks was examined in dogs. At a dose-rate of 75, 128, and 263 mGy/d the incidence of acute lymphohematopoietic suppression (aplastic anemia) and associated septic complications was 73%, 87%, and 100%, respectively, and it increased in dose-dependent manner. By contrast, at dose-rates below 75 mGy/d, late cancers contributed significantly to the death of relatively long-lived animals, whose mean survival time was 1800 days. Myeloproliferative disease (MPD), mainly myeloid leukemia, was the dominant pathology seen at the higher daily dose-rates (18.8-75 mGy/d). When daily exposure was carried out continuously, the incidence of MPD was quite high. It should be noted that the induction radiation-induced MPD in this study was highly significant, because spontaneous MPD is exceedingly rare in the dog. However, when the daily dose-rate was reduced further or exposure was discontinued, the incidence of MPD declined significantly. At these lower dose-rates, solid tumors contributed heavily to the life-shortening effects of chronic irradiation. The induction and progression of these survival-compromising, late forms of pathology appeared to be driven by the degree of hematopoietic suppression that occurred early during the exposure phase, and in turn by the capacity of hematopoietic system to repair itself, recover, and to accommodate under chronic radiation stress. (K.H.)

  13. Experimental validation of Monte Carlo depth-dose calculations using radiochromic dye film dosimetry for a beta-gamma {sup 153}Sm radionuclide applied to the treatment of rheumatoid arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Villarreal-Barajas, J.E.; Ferro-Flores, G.; Hernandez-Oviedo, O

    2002-07-01

    In this work we compare the Monte Carlo (MCNP4B) calculated beta-gamma depth-dose profile for a liquid {sup 153}Sm beta-gamma source used in radiation synovectomy with the experimental depth-dose distribution obtained using radiochromic dye film dosimetry. The calculated and experimental depth-dose distribution shows a very good agreement (within 5%) in the region where the dose deposition is dominated by the beta particle component (first 800 {mu}m depth on tissue-equivalent material). The agreement worsens, reaching a maximum deviation of 15%, at depths close to the maximum range of the beta particles. Finally the agreement improves for the region where the gamma component accounts for one-third of the total absorbed dose (depths >1 mm ). The possible contributions to these differences are discussed, as well as their relevance for the application of {sup 153}Sm in the treatment of rheumatoid arthritis. (author)

  14. Gamma dose measurements at Zion and Fort Calhoun Stations

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, N.C.; Bunting, R.L.; Nieschmidt, E.B.; Croney, S.T.; Kynaston, R.L.; McIssac, C.V.; Underwood, D.R.

    1979-04-01

    The objective of this study was to provide experimental data to the NRC for evaluation of the gamma radiation fields in personnel access areas within operating LWR's. As partial fulfillment of this objective, data were obtained at two PWR's on in-plant gamma radiation fields in areas such as inside and outside equipment cubicles and spent fuel pool areas. Also, airborne radionuclide concentrations were measured in areas where plant personnel could be working during a refueling outage. Data presented were obtained at the Zion Station operated by Commonwealth Edison Co. and located near Zion, Illinois, and at the Fort Calhoun Station - Unit 1 operated by the Omaha Public Power District and located near Blair, Nebraska.

  15. Assessment of individual organ doses in a realistic human phantom from neutron and gamma stimulated spectroscopy of the breast and liver

    Energy Technology Data Exchange (ETDEWEB)

    Belley, Matthew D. [Medical Physics Graduate Program, Duke University, Durham 27705, North Carolina (United States); Segars, William Paul; Kapadia, Anuj J., E-mail: anuj.kapadia@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina and Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham 27710, North Carolina (United States)

    2014-06-15

    Purpose: Understanding the radiation dose to a patient is essential when considering the use of an ionizing diagnostic imaging test for clinical diagnosis and screening. Using Monte Carlo simulations, the authors estimated the three-dimensional organ-dose distribution from neutron and gamma irradiation of the male liver, female liver, and female breasts for neutron- and gamma-stimulated spectroscopic imaging. Methods: Monte Carlo simulations were developed using the Geant4 GATE application and a voxelized XCAT human phantom. A male and a female whole body XCAT phantom was voxelized into 256 × 256 × 600 voxels (3.125 × 3.125 × 3.125 mm{sup 3}). A monoenergetic rectangular beam of 5.0 MeV neutrons or 7.0 MeV photons was made incident on a 2 cm thick slice of the phantom. The beam was rotated at eight different angles around the phantom ranging from 0° to 180°. Absorbed dose was calculated for each individual organ in the body and dose volume histograms were computed to analyze the absolute and relative doses in each organ. Results: The neutron irradiations of the liver showed the highest organ dose absorption in the liver, with appreciably lower doses in other proximal organs. The dose distribution within the irradiated slice exhibited substantial attenuation with increasing depth along the beam path, attenuating to ∼15% of the maximum value at the beam exit side. The gamma irradiation of the liver imparted the highest organ dose to the stomach wall. The dose distribution from the gammas showed a region of dose buildup at the beam entrance, followed by a relatively uniform dose distribution to all of the deep tissue structures, attenuating to ∼75% of the maximum value at the beam exit side. For the breast scans, both the neutron and gamma irradiation registered maximum organ doses in the breasts, with all other organs receiving less than 1% of the breast dose. Effective doses ranged from 0.22 to 0.37 mSv for the neutron scans and 41 to 66 mSv for the gamma

  16. Estimation of the committed radiation dose resulting from gamma radionuclides ingested with food.

    Science.gov (United States)

    Godyń, Piotr; Dołhańczuk-Śródka, Agnieszka; Ziembik, Zbigniew; Moliszewska, Ewa

    The objective of the study was to estimate the value of the radiation dose absorbed in consequence of consumption of popular food products for individual age groups. Potatoes, corn and sugar beet were selected for the study. Edible parts of these plants were collected in experimental fields of the KWS Lochów Polska Sp. z o.o. seeding company in Kondratowice (Poland). On the basis of the obtained study results, it can be stated that in consequence of consumption of the selected food products, people may receive increased doses from both natural and artificial radioactive isotopes. The doses calculated for several age groups do not show any health hazards in consequence of consumption of the tested food. One of the determined radionuclides was (137)Cs; however, its presence in the absorbed dose is lower than the doses from natural radioactive isotopes, in particular (40)K.

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

    Science.gov (United States)

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

    2001-09-01

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

  18. 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.

  19. High-Resolution Gamma-Ray Spectrometers using Bulk Absorbers Coupled to Mo/Cu Multilayer Superconducting Transition-Edge Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Chow, D.T.; Loshak, A.; Van Den Berg, M.L.; Frank, M.; Barbee Jr., T.W.; Labov, S.E.

    2000-07-04

    In x-ray and gamma-ray spectroscopy, it is desirable to have detectors with high energy resolution and high absorption efficiency. At LLNL, we have developed superconducting tunnel junction-based single photon x-ray detectors with thin film absorbers that have achieved these goals for photon energies up to 1 keV. However, for energies above 1 keV, the absorption efficiency of these thin-film detectors decreases drastically. We are developing the use of high-purity superconducting bulk materials as microcalorimeter absorbers for high-energy x-rays and gamma rays. The increase in absorber temperature due to incident photons is sensed by a superconducting transition-edge sensor (TES) composed of a Mo/Cu multilayer thin film. Films of Mo and Cu are mutually insoluble and therefore very stable and can be annealed. The multilayer structure allows scaling in thickness to optimize heat capacity and normal state resistance. We measured an energy resolution of 70 eV for 60 keV incident gamma-rays with a 1 x 1 x 0.25 mm{sup 3} Sn absorber. We present x-ray and gamma-ray results from this detector design with a Sn absorber. We also propose the use of an active negative feedback voltage bias to improve the performance of our detector and show preliminary results.

  20. 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

  1. Selective source blocking for Gamma Knife radiosurgery of trigeminal neuralgia based on analytical dose modelling

    Science.gov (United States)

    Li, Kaile; Ma, Lijun

    2004-08-01

    We have developed an automatic critical region shielding (ACRS) algorithm for Gamma Knife radiosurgery of trigeminal neuralgia. The algorithm selectively blocks 201 Gamma Knife sources to minimize the dose to the brainstem while irradiating the root entry area of the trigeminal nerve with 70-90 Gy. An independent dose model was developed to implement the algorithm. The accuracy of the dose model was tested and validated via comparison with the Leksell GammaPlan (LGP) calculations. Agreements of 3% or 3 mm in isodose distributions were found for both single-shot and multiple-shot treatment plans. After the optimized blocking patterns are obtained via the independent dose model, they are imported into the LGP for final dose calculations and treatment planning analyses. We found that the use of a moderate number of source plugs (30-50 plugs) significantly lowered (~40%) the dose to the brainstem for trigeminal neuralgia treatments. Considering the small effort involved in using these plugs, we recommend source blocking for all trigeminal neuralgia treatments with Gamma Knife radiosurgery.

  2. Aging of magnesium stearate under high doses gamma irradiation and oxidative conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lebeau, D.; Beuvier, L.; Cornaton, M. [CEA, DEN, DPC, SECR, LRMO, F-91191 Gif-sur-Yvette (France); Miserque, F. [CEA, DEN, DPC, SCCME, LECA, F-91191 Gif-sur-Yvette (France); Tabarant, M. [CEA, DEN, DPC, SEARS, LISL, F-91191 Gif-sur-Yvette (France); Esnouf, S. [CEA, DEN, DPC, SECR, LRMO, F-91191 Gif-sur-Yvette (France); Ferry, M., E-mail: muriel.ferry@cea.fr [CEA, DEN, DPC, SECR, LRMO, F-91191 Gif-sur-Yvette (France)

    2015-05-15

    Highlights: • Magnesium stearate was radio-oxidized at very high doses using gamma-rays. • H{sub 2} emission was estimated as a function of the integrated dose. • Modifications in the organic solid were followed as a function of the integrated dose. • A non-exhaustive degradation mechanism of magnesium stearate was proposed. - Abstract: In nuclear waste packages conditioning processes, magnesium stearate is widely used because of its high lubricating properties. For safety purposes, the radiolytic degradation of these organic materials has to be better understood to be able to predict their aging in repository conditions. This study reports the radiolytic degradation of magnesium stearate, using gamma-rays at room temperature and under air. Modifications were followed using different analytical tools (XPS, ATR-FTIR, ICP-AES, ATG and mass spectrometry). It has been observed that molecules mainly formed up to 1000 kGy of gamma irradiation dose under radio-oxidation are alkanes, hydroperoxides, double bonds in the aliphatic chain, carboxylates with aliphatic chain shorter than the one of stearate and ketones. At a dose of 4000 kGy, dicarboxylic acids are observed: the formation of these molecules needs a dose of at least 1000 kGy to be created under radio-oxidation. These observations allow us to propose a non-exhaustive degradation mechanism of magnesium stearate under gamma-irradiation at room temperature and under air.

  3. Selective source blocking for Gamma Knife radiosurgery of trigeminal neuralgia based on analytical dose modelling

    Energy Technology Data Exchange (ETDEWEB)

    Li Kaile; Ma Lijun [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21210 (United States)

    2004-08-07

    We have developed an automatic critical region shielding (ACRS) algorithm for Gamma Knife radiosurgery of trigeminal neuralgia. The algorithm selectively blocks 201 Gamma Knife sources to minimize the dose to the brainstem while irradiating the root entry area of the trigeminal nerve with 70-90 Gy. An independent dose model was developed to implement the algorithm. The accuracy of the dose model was tested and validated via comparison with the Leksell GammaPlan (LGP) calculations. Agreements of 3% or 3 mm in isodose distributions were found for both single-shot and multiple-shot treatment plans. After the optimized blocking patterns are obtained via the independent dose model, they are imported into the LGP for final dose calculations and treatment planning analyses. We found that the use of a moderate number of source plugs (30-50 plugs) significantly lowered ({approx}40%) the dose to the brainstem for trigeminal neuralgia treatments. Considering the small effort involved in using these plugs, we recommend source blocking for all trigeminal neuralgia treatments with Gamma Knife radiosurgery.

  4. A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions.

    Science.gov (United States)

    Podesta, Mark; Persoon, Lucas C G G; Verhaegen, Frank

    2014-10-21

    Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors.The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields

  5. Dose Rate and Mass Attenuation Coefficients of Gamma Ray for Concretes

    CERN Document Server

    Abdel-Latif, A A; Kansouh, W A; El-Sayed, F H

    2003-01-01

    This work is concerned with the study of the leakage gamma ray dose and mass attenuation coefficients for ordinary, basalt and dolomite concretes made from local ores. Concretes under investigation were constructed from gravel, basalt and dolomite ores, and then reconstructed with the addition of 3% steel fibers by weight. Measurements were carried out using a collimated beam from sup 6 sup 0 Co gamma ray source and sodium iodide (3x3) crystal with the genie 2000 gamma spectrometer. The obtained fluxes were transformed to gamma ray doses and displayed in the form of gamma ray dose rates distribution. The displayed curves were used to estimate the linear attenuation coefficients (mu), the relaxation lengths (lambda), half value layer (t sub 1 /2) and tenth value layer (t sub 1 /10). Also, The total mass attenuation coefficients of gamma ray have been calculated to the concerned concretes using XCOM (version 3.1) program and database elements cross sections from Z=1 to 100 at energies from 10 keV to 100 MeV. In...

  6. Terrestrial gamma radiation dose measurement and health hazard along river Alaknanda and Ganges in India

    Directory of Open Access Journals (Sweden)

    Prerna Sharma

    2014-10-01

    Full Text Available Direct measurement of absorbed dose rate in air due to exposure from outdoor terrestrial γ radiation and assessment of consequent public health hazard continues to be of environmental and public concern. Present study was aimed to establish a baseline data of annual effective dose and to assess the associated health risk from outdoor terrestrial γ radiation along the river Alaknanda and Ganges of India. Terrestrial γ radiation exposure doses (excluding cosmic radiation were measured using a Plastic Scintillation Counter. Absorbed dose rates in air were measured at eight designated locations from Nandprayag to Allahabad along the river. From the average absorbed dose rates, annual effective dose (AED and excess life time cancer risks (ELCR were calculated by standard method. Results showed that absorbed dose rates in air ranged between 81.33 ± 2.34 nSv.h−1 and 144 ± 5.77 nSv.h−1 and calculated AED ranged between 0.10 ± 0.012 mSv.y−1 to 0.18 ± 0.007 mSv.y−1 at the designated locations along these rivers. Calculated ELCR were found in the range of 0.375 × 10−3 to 0.662 × 10−3. Present study measured the outdoor γ radiation levels along the rivers. The calculated annual effective doses and life time cancer risk were found higher than the world average value at higher altitudes. But the measured doses and calculated risks at plains were close to that of reported average values.

  7. 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)

  8. {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

  9. Gamma Dose Distribution Studies in Ducted Shield Material Having Different Configurations

    Science.gov (United States)

    Sayed Ahmed, F. M.

    In the present work the radial distribution of total gamma doses arising from the interaction of reactor neutrons and gamma radiations inside ilmenite heavy concrete shield are measured. The ilmenite concrete is pierced with neutral beam injector ducts having different diameters and lengths. The results obtained show a relative increase in radial gamma doses at a distance of 10 cm from the neutral beam end. An empirical formula was obtained, fitting the measured gamma doses at the peak position in good agreement within a factor of 1.27. Moreover the variation of the total gamma radiation was measured along straight filled ducted with different diameters and length. The experimental data obtained show a reasonable agreement with calculated ones. The scattered as well as unscattered components of the gamma radiation transmitted through a straight duct were investigated. An empirical formula describing this behaviour was obtained.Translated AbstractDie Untersuchung der Dosisverteilung in verschieden konfigurierten Schirmmaterialien mit DurchführungenIn der vorliegenden Arbeit wird die radiale Verteilung der totalen -Dosis gemessen, wie sie aus der Wechselwirkung von Reaktorneutronen und -Strahlung innerhalb eines Betonschirms entsteht. Der Beton ist mit verschieden großen und langen Durchführungen versehen. Die erhaltenen Resultate zeigen einen relativen Intensitätspik 10 cm vor Durchführungsende. Eine empirische Formel wird aufgestellt, die diese Verhältnisse relativ gut (um den Faktor 1.27) wiedergibt. Darüber hinaus wurde die Gamma-Strahlung entlang gerader, gefüllter Durchführungen unterschiedlicher Abmessungen gemessen. Übereinstimmung mit berechneten Werten konnte erzielt werden. Sowohl die gestreuten als auch die ungestreuten Komponenten der Gamma-Strahlung in einer geraden Durchführung wurden untersucht und eine beschriebene, empirische Formel dafür angegeben.

  10. Dose mapping of dried figs treated by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Polonia, I.; Portugal, L.; Andrade, M. E

    1998-06-01

    The irradiation parameters of two varieties of dried figs were determined in a fixed position. The Dose Uniformity (U=Dmax/Dmin) obtained for Fricke Dosimeter was 1.4 and for YR Gammachrome 1.3. The isodose curves were built using a geostatistical gridding method, the Kriging method.

  11. Determination of absorbed dose in electron beams using parallel-plane ionization chambers; Determinacao de dose absorvida em feixes de eletrons utilizando camaras de ionizacao de placas paralelas

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, Roseli T.; Caldas, Linda V.E. [Instituto de Pesquisas Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: lcaldas@ipen.br

    2004-06-01

    Objective: The objective of this paper was to establish a procedure for the determination of calibration factors and absorbed doses in electron beams. Materials And Methods: An irradiator with a {sup 60} Co source and a linear accelerator Varian, Clinac 2100C, with photon and electron beams, were utilized. Thimble type and parallel-plane ionization chambers were tested. Results: The measurement systems showed very good results in the preliminary tests (response stability and leakage current). The ionization chambers used for electron beam dosimetry were calibrated using four different methods. For the determination of absorbed dose, three methodologies recommended by the International Atomic Energy Agency were applied. Concordant results were obtained in almost all cases. Conclusion: The majority of the ionization chambers tested showed good results according to the established international limits. (author)

  12. MO-F-CAMPUS-T-03: Continuous Dose Delivery with Gamma Knife Perfexion

    Energy Technology Data Exchange (ETDEWEB)

    Ghobadi,; Li, W; Chung, C; Jaffray, D [Princess Margaret Cancer Centre and University Health Network, Toronto, Ontario (Canada); Aleman, D [University of Toronto, Toronto, Ontario (Canada)

    2015-06-15

    Purpose: We propose continuous dose delivery techniques for stereotactic treatments delivered by Gamma Knife Perfexion using inverse treatment planning system that can be applied to various tumour sites in the brain. We test the accuracy of the plans on Perfexion’s planning system (GammaPlan) to ensure the obtained plans are viable. This approach introduces continuous dose delivery for Perefxion, as opposed to the currently employed step-and-shoot approaches, for different tumour sites. Additionally, this is the first realization of automated inverse planning on GammaPlan. Methods: The inverse planning approach is divided into two steps of identifying a quality path inside the target, and finding the best collimator composition for the path. To find a path, we select strategic regions inside the target volume and find a path that visits each region exactly once. This path is then passed to a mathematical model which finds the best combination of collimators and their durations. The mathematical model minimizes the dose spillage to the surrounding tissues while ensuring the prescribed dose is delivered to the target(s). Organs-at-risk and their corresponding allowable doses can also be added to the model to protect adjacent organs. Results: We test this approach on various tumour sizes and sites. The quality of the obtained treatment plans are comparable or better than forward plans and inverse plans that use step- and-shoot technique. The conformity indices in the obtained continuous dose delivery plans are similar to those of forward plans while the beam-on time is improved on average (see Table 1 in supporting document). Conclusion: We employ inverse planning for continuous dose delivery in Perfexion for brain tumours. The quality of the obtained plans is similar to forward and inverse plans that use conventional step-and-shoot technique. We tested the inverse plans on GammaPlan to verify clinical relevance. This research was partially supported by Elekta

  13. An empirical model for independent dose verification of the Gamma Knife treatment planning.

    Science.gov (United States)

    Phaisangittisakul, Nakorn; Ma, Lijun

    2002-09-01

    A formalism for an independent dose verification of the Gamma Knife treatment planning is developed. It is based on the approximation that isodose distribution for a single shot is in the shape of an ellipsoid in three-dimensional space. The dose profiles for a phantom along each of the three major axes are fitted to a function which contains the terms that represent the contributions from a point source, an extrafocal scattering, and a flat background. The fitting parameters are extracted for all four helmet collimators, at various shot locations, and with different skull shapes. The 33 parameters of a patient's skull shape obtained from the Skull Scaling Instrument measurements are modeled for individual patients. The relative doses for a treatment volume in the form of 31 x 31 x 31 matrix of points are extracted from the treatment planning system, the Leksell Gamma-Plan (LGP). Our model evaluates the relative doses using the same input parameters as in the LGP, which are skull measurement data, shot location, weight, gamma-angle of the head frame, and helmet collimator size. For 29 single-shot cases, the discrepancy of dose at the focus point between the calculation and the LGP is found to be within -1% to 2%. For multi-shot cases, the value and the coordinate of the maximum dose point from the calculation agree within +/-7% and +/-3 mm with the LGP results. In general, the calculated doses agree with the LGP calculations within +/-10% for the off-center locations. Results of calculation with this method for the dimension and location of the 50% isodose line are in good agreement with results from Leksell GammaPlan. Therefore, this method can be served as a useful tool for secondary quality assurance of Gamma Knife treatment plans.

  14. Establishment and validation of a dose-effect curve for {gamma}-rays by cytogenetic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Barquinero, Joan F.; Caballin, Maria Rosa [Unitat d`Antropologia, Departament de Biologia Animal, Biologia Vegetal i Ecologia, Facultat de Ciencies, Universitat Autonoma de Barcelona, Bellaterra (Spain); Barrios, Leonardo; Ribas, Montserrat [Unitat de Biologia Cel.lular, Departament de Biologia Cel.lular i Fisiologia, Facultat de Ciencies, Universitat Autonoma de Barcelona, Bellaterra (Spain); Miro, Rosa [Institut de Biologia Fondamental `Vicent Villar Palasi`, Universitat Autonoma de Barcelona, Barcelona (Spain); Egozcue, Josep [Servei d`Oncologia, Hospital de la Santa Crue i Sant Pau, Universitat Autonome de Barcelona, Barcelona (Spain)

    1995-01-01

    A dose-effect curve obtained by analysis of dicentric chromosomes after irradiation of peripheral blood samples, from one donor, at 11 different doses of {gamma}-rays is presented. For the elaboration of this curve, more than 18,000 first division metaphases have been analyzed. The results fit very well to the linear-quadratic model. To validate the curve, samples from six individuals (three controls and three occupationally exposed persons) were irradiated at 2 Gy. The results obtained, when compared with the curve, showed that in all cases the 95% confidence interval included the 2 Gy dose, with estimated dose ranges from 1.82 to 2.19 Gy.

  15. 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

  16. Cell engineering: nanometric grafting of poly-N-isopropylacrylamide onto polystyrene film by different doses of gamma radiation

    Directory of Open Access Journals (Sweden)

    Esmaeil Biazar

    2010-07-01

    Full Text Available Esmaeil Biazar1, Reza Zeinali2, Naser Montazeri1, Khalil Pourshamsian1, Mahmoud Jabarvand Behrouz3, Azadeh Asefnejad2, Ahad Khoshzaban3, Gholamreza Shahhosseini4, Mostafa Soleimannejad Najafabadi5, Reza Abyani2, Hamidreza Jamalzadeh6, Mahdi Fouladi1, Sasan Rahbar F Hagh7, Aylar Shams Khamaneh1, Soudabeh Kabiri1, Saeed Heidari Keshel3, Ana Mansourkiaei61Department of Chemistry, 6Department of Biology, 7Young Researchers Club, Islamic Azad University, Tonekabon Branch, Mazandaran, Iran; 2Biomedical Engineering Faculty, Islamic Azad University, Science and Research Branch, Tehran, Iran; 3Stem Cell Preparation Unit, Farabi Hospital, Tehran University Medical Science, Tehran, Iran; 4Agricultural, Medical and Industrial Research School, Nuclear Science and Techniques Research Institute, Karaj, Iran; 5Material Engineering Faculty, Islamic Azad University, Najafabad Branch, Isfahan, IranAbstract: Poly-N-isopropylacrylamide was successfully grafted onto a polystyrene cell culture dish and γ-preirradiated in air. In this study, the effect of a γ-pre-irradiation dose of radiation (radiation absorbed dosages of 10, 20, 30, 40 KGy under appropriate temperature and grafting conditions was investigated. The Fourier transform infrared spectroscopy analysis showed the existence of the graft poly-N-isopropylacrylamide (PNIPAAm on the substrate. The optimal value of the dose for grafting was 40 KGy at 50°C. The scanning electron microscopy and atomic force microscopy (AFM images clearly showed that increasing the absorbed dose of radiation would increase the amount of grafting. Surface topography and graft thickness in AFM images of the radiated samples showed that the PNIPAAm at the absorbed dose of radiation was properly grafted. The thickness of these grafts was about 50–100 nm. The drop water contact angles of the best grafted sample at 37°C and 10°C were 55.3 ± 1.2° and 61.2 ± 0.9° respectively, which showed the hydrophilicity and hydrophobicity of

  17. 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.

  18. Low-dose radiation modifies skin response to acute gamma-rays and protons.

    Science.gov (United States)

    Mao, Xiao Wen; Pecaut, Michael J; Cao, Jeffrey D; Moldovan, Maria; Gridley, Daila S

    2013-01-01

    The goal of the present study was to obtain pilot data on the effects of protracted low-dose/low-dose-rate (LDR) γ-rays on the skin, both with and without acute gamma or proton irradiation (IR). Six groups of C57BL/6 mice were examined: a) 0 Gy control, b) LDR, c) Gamma, d) LDR+Gamma, e) Proton, and f) LDR+Proton. LDR radiation was delivered to a total dose of 0.01 Gy (0.03 cGy/h), whereas the Gamma and Proton groups received 2 Gy (0.9 Gy/min and 1.0 Gy/min, respectively). Assays were performed 56 days after exposure. Skin samples from all irradiated groups had activated caspase-3, indicative of apoptosis. The significant (pGamma and Proton groups were not present when LDR pre-exposure was included. However, the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay for DNA fragmentation and histological examination of hematoxylin and eosin-stained sections revealed no significant differences among groups, regardless of radiation regimen. The data demonstrate that caspase-3 activation initially triggered by both forms of acute radiation was greatly elevated in the skin nearly two months after whole-body exposure. In addition, LDR γ-ray priming ameliorated this response.

  19. Incase of Same Region Treatment by using a Tomotherapy and a Linear Accelerator Absorbed Dose Evaluation of Normal Tissues and a Tumor

    Energy Technology Data Exchange (ETDEWEB)

    Cheon, Geum Seong; Kim, Chang Uk; Kim, Hoi Nam; Heo, Gyeong Hun; Song, Jin Ho; Hong, Joo Yeong [Dept. of Radiation Oncology, Catholic University Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Jeong, Jae Yong [Dept. of Radiation Oncology, Inje University Sanggye Paik Hospital, Seoul (Korea, Republic of)

    2010-09-15

    Treating same region with different modalities there is a limit to evaluate the total absorbed dose of normal tissues. The reason is that it does not support to communication each modalities yet. In this article, it evaluates absorbed dose of the patients who had been treated same region by a tomotherapy and a linear accelerator. After reconstructing anatomic structure with a anthropomorphic phantom, administrate 45 Gy to a tumor in linac plan system as well as prescribe 15 Gy in tomotherapy plan system for make an ideal treatment plan. After the plan which made by tomoplan system transfers to the oncentra plan system for reproduce plan under the same condition and realize total treatment plan with summation 45 Gy linac treatment plan. To evaluate the absorbed dose of two different modalities, do a comparative study both a simple summation dose values and integration dose values. Then compare and analyze absorbed dose of normal tissues and a tumor with the patients who had been exposured radiation by above two different modalities. The result of compared data, in case of minimum dose, there are big different dose values in spleen (12.4%). On the other hand, in case of the maximum dose, it reports big different in a small bowel (10.2%) and a cord (5.8%) in head and neck cancer patients, there presents that oral (20.3%), right lens (7.7%) in minimum dose value. About maximum dose, it represents that spinal (22.5), brain stem (12%), optic chiasm (8.9%), Rt lens (11.5%), mandible (8.1%), pituitary gland (6.2%). In case of Rt abdominal cancer patients, there represents big different minimum dose as Lt kidney (20.3%), stomach (8.1%) about pelvic cancer patients, it reports there are big different in minimum dose as a bladder (15.2%) as well as big different value in maximum dose as a small bowel (5.6%), a bladder (5.5%) in addition, making treatment plan it is able us to get. In case of comparing both simple summation absorbed dose and integration absorbed dose, the

  20. Evaluation of excess life time cancer risk from gamma dose rates in Jhelum valley

    Directory of Open Access Journals (Sweden)

    Muhammad Rafique

    2014-01-01

    Full Text Available Human beings are continuously exposed to the radiations coming from outside and inside their bodies. Outside and inside radiations are coming from ground, building materials, food, air, the universe and even elements within human own bodies. According to UNSCEAR 2000 report, background radiations deliver an average effective dose of 2.4 mSv per person worldwide. Sustained exposure from high background radiation levels may pose substantial health threats to general public. In the current study we are presenting the results of ambient outdoor gamma dose rates measured for Jhelum valley of the state of Azad Kashmir. This study has been carried out by using Ludlum micrometer-19 which is an active and portable detector. Effects of different parameters of interest on the measured values of gamma dose rates have been investigated. For the region under investigation, minimum and maximum indoor gamma dose rates were found as 610 ± 4.05 μGy·y−1 and 1372 ± 2.7 μGy·y−1, respectively, whilst minimum and maximum outdoor gamma dose rates were found as 495 ± 4.49 μGy·y−1 and 1296 ± 2.78 μGy·y−1, respectively. Overall arithmetic mean (A.M and geometric mean (G.M values of gamma dose rates for indoor and outdoor measurements were found as 940 ± 3.26 μGy·y−1, 892 ± 3.35 μGy·y−1 and 928 ± 3.28 μGy·y−1, 880 ± 3.37 μGy·y−1 respectively. Excess life time cancer risk (ELCR for indoor exposure ranges from 1.057 × 10−3 to 2.377 × 10−3 with an average value of 1.629 × 10−3. For outdoor exposure, ELCR varies from 0.352 × 10−3 to 0.792 × 10−3 with mean value of 0.543 × 10−3. Average values of indoor gamma doses were found to be greater than the world population-weighted average for indoor gamma dose rates (780 μGy·y−1 or 89 nGy h−1.

  1. SU-E-T-453: Optimization of Dose Gradient for Gamma Knife Radiosurgery.

    Science.gov (United States)

    Sheth, N; Chen, Y; Yang, J

    2012-06-01

    The goals of stereotactic radiosurgery (SRS) are the ablation of target tissue and sparing of critical normal tissue. We develop tools to aid in the selection of collimation and prescription (Rx) isodose line to optimize the dose gradient for single isocenter intracranial stereotactic radiosurgery (SRS) with GammaKnife 4C utilizing the updated physics data in GammaPlan v10.1. Single isocenter intracranial SRS plans were created to treat the center of a solid water anthropomorphism head phantom for each GammaKnife collimator (4 mm, 8 mm, 14 mm, and 18 mm). The dose gradient, defined as the difference of effective radii of spheres equal to half and full Rx volumes, and Rx treatment volume was analyzed for isodoses from 99% to 20% of Rx. The dosimetric data on Rx volume and dose gradient vs. Rx isodose for each collimator was compiled into an easy to read nomogram as well as plotted graphically. The 4, 8, 14, and 18 mm collimators have the sharpest dose gradient at the 64%, 70%, 76%, and 77% Rx isodose lines, respectively. This corresponds to treating 4.77 mm, 8.86 mm, 14.78 mm, and 18.77 mm diameter targets with dose gradients radii of 1.06 mm, 1.63 mm, 2.54 mm, and 3.17 mm, respectively. We analyzed the dosimetric data for the most recent version of GammaPlan treatment planning software to develop tools that when applied clinically will aid in the selection of a collimator and Rx isodose line for optimal dose gradient and target coverage for single isocenter intracranial SRS with GammaKnife 4C. © 2012 American Association of Physicists in Medicine.

  2. Calibration of GafChromic EBT3 for absorbed dose measurements in 5 MeV proton beam and (60)Co γ-rays.

    Science.gov (United States)

    Vadrucci, M; Esposito, G; Ronsivalle, C; Cherubini, R; Marracino, F; Montereali, R M; Picardi, L; Piccinini, M; Pimpinella, M; Vincenti, M A; De Angelis, C

    2015-08-01

    To study EBT3 GafChromic film in low-energy protons, and for comparison purposes, in a reference (60)Co beam in order to use it as a calibrated dosimetry system in the proton irradiation facility under construction within the framework of the Oncological Therapy with Protons (TOP)-Intensity Modulated Proton Linear Accelerator for RadioTherapy (IMPLART) Project at ENEA-Frascati, Italy. EBT3 film samples were irradiated at the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Legnaro, Italy, with a 5 MeV proton beam generated by a 7 MV Van de Graaff CN accelerator. The nominal dose rates used were 2.1 Gy/min and 40 Gy/min. The delivered dose was determined by measuring the particle fluence and the energy spectrum in air with silicon surface barrier detector monitors. A preliminary study of the EBT3 film beam quality dependence in low-energy protons was conducted by passively degrading the beam energy. EBT3 films were also irradiated at ENEA-National Institute of Ionizing Radiation Metrology with gamma radiation produced by a (60)Co source characterized by an absorbed dose to water rate of 0.26 Gy/min as measured by a calibrated Farmer type ionization chamber. EBT3 film calibration curves were determined by means of a set of 40 film pieces irradiated to various doses ranging from 0.5 Gy to 30 Gy absorbed dose to water. An EPSON Expression 11000XL color scanner in transmission mode was used for film analysis. Scanner response stability, intrafilm uniformity, and interfilm reproducibility were verified. Optical absorption spectra measurements were performed on unirradiated and irradiated EBT3 films to choose the most sensitive color channel to the dose range used. EBT3 GafChromic films show an under response up to about 33% for low-energy protons with respect to (60)Co gamma radiation, which is consistent with the linear energy transfer dependence already observed with higher energy protons, and a negligible dose-rate dependence in the 2-40 Gy/min range

  3. Calibration of GafChromic EBT3 for absorbed dose measurements in 5 MeV proton beam and {sup 60}Co γ-rays

    Energy Technology Data Exchange (ETDEWEB)

    Vadrucci, M., E-mail: monia.vadrucci@enea.it; Ronsivalle, C.; Marracino, F.; Montereali, R. M.; Picardi, L.; Piccinini, M.; Vincenti, M. A. [Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA)–Application of Radiations Technical Unit, Via E. Fermi 45, Frascati, Rome 00044 (Italy); Esposito, G.; De Angelis, C. [Istituto Superiore di Sanità (ISS), Viale Regina Elena 299, Rome I-00161, Italy and INFN, Sezione di Roma1, Gruppo Collegato Sanità, Rome 00100 (Italy); Cherubini, R. [INFN-Laboratori Nazionali di Legnaro, Viale dell’Università 2, Legnaro, Padova I-35020 (Italy); Pimpinella, M. [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (ENEA–INMRI), Via Anguillarese 301, Rome 00123 (Italy)

    2015-08-15

    Purpose: To study EBT3 GafChromic film in low-energy protons, and for comparison purposes, in a reference {sup 60}Co beam in order to use it as a calibrated dosimetry system in the proton irradiation facility under construction within the framework of the Oncological Therapy with Protons (TOP)-Intensity Modulated Proton Linear Accelerator for RadioTherapy (IMPLART) Project at ENEA-Frascati, Italy. Methods: EBT3 film samples were irradiated at the Istituto Nazionale di Fisica Nucleare—Laboratori Nazionali di Legnaro, Italy, with a 5 MeV proton beam generated by a 7 MV Van de Graaff CN accelerator. The nominal dose rates used were 2.1 Gy/min and 40 Gy/min. The delivered dose was determined by measuring the particle fluence and the energy spectrum in air with silicon surface barrier detector monitors. A preliminary study of the EBT3 film beam quality dependence in low-energy protons was conducted by passively degrading the beam energy. EBT3 films were also irradiated at ENEA-National Institute of Ionizing Radiation Metrology with gamma radiation produced by a {sup 60}Co source characterized by an absorbed dose to water rate of 0.26 Gy/min as measured by a calibrated Farmer type ionization chamber. EBT3 film calibration curves were determined by means of a set of 40 film pieces irradiated to various doses ranging from 0.5 Gy to 30 Gy absorbed dose to water. An EPSON Expression 11000XL color scanner in transmission mode was used for film analysis. Scanner response stability, intrafilm uniformity, and interfilm reproducibility were verified. Optical absorption spectra measurements were performed on unirradiated and irradiated EBT3 films to choose the most sensitive color channel to the dose range used. Results: EBT3 GafChromic films show an under response up to about 33% for low-energy protons with respect to {sup 60}Co gamma radiation, which is consistent with the linear energy transfer dependence already observed with higher energy protons, and a negligible dose

  4. Monitoring performance of the cameras under the high dose-rate gamma ray environments.

    Science.gov (United States)

    Cho, Jai Wan; Choi, Young Soo; Jeong, Kyung Min

    2014-05-01

    CCD/CMOS cameras, loaded on a robot system, are generally used as the eye of the robot and monitoring unit. A major problem that arises when dealing with images provided by CCD/CMOS cameras under severe accident situations of a nuclear power plant is the presence of speckles owing to the high dose-rate gamma irradiation fields. To use a CCD/CMOS camera as a monitoring unit in a high radiation area, the legibility of the camera image in such intense gamma-radiation fields should therefore be defined. In this paper, the authors describe the monitoring index as a figure of merit of the camera's legibleness under a high dose-rate gamma ray irradiation environment. From a low dose-rate (10 Gy h) to a high dose-rate (200 Gy h) level, the legible performances of the cameras owing to the speckles are evaluated. The numbers of speckles generated by gamma ray irradiation in the camera image are calculated by an image processing technique. The legibility of the sensor indicator (thermo/hygrometer) owing to the number of speckles is also presented.

  5. A computational study to evaluate indoor gamma dose-rate on the basis of outdoor measurements

    Energy Technology Data Exchange (ETDEWEB)

    Nuccetelli, C.; Menghi, E.; Bochicchio, F. [Istituto Superiore di Sanita, Roma (Italy)

    2006-07-01

    A new method to estimate the indoor gamma dose rate has been developed. This method is based on outdoor gamma dose rate measurements and a computational model that requires the knowledge of some structural and geometrical characteristics of the dwelling. It can be a very useful tool in situations in which it is impossible entering the dwellings to measure the indoor gamma dose rate, such as epidemiological studies and other surveys. To validate the method, estimates and actual indoor measurements have been compared for a sample of dwellings. In a first phase, indoor gamma dose rate estimates were obtained using the detailed dwelling information contained in questionnaire filled-in during the indoor measurements. This first comparison gave excellent results. A more general and less site dependent approach has now been implemented, assuming average values for many indoor parameters instead of using questionnaire data, in order to evaluate the predictive characteristics of this method for a practical use. In this paper, the new procedure is presented and the results obtained till now are summarized. (authors)

  6. Moving from gamma passing rates to patient DVH-based QA metrics in pretreatment dose QA

    Energy Technology Data Exchange (ETDEWEB)

    Zhen, Heming; Nelms, Benjamin E.; Tome, Wolfgang A. [Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705 (United States); Department of Human Oncology, University of Wisconsin, Madison, Wisconsin 53792 and Canis Lupus LLC, Merrimac, Wisconsin 53561 (United States); Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705 and Department of Human Oncology, University of Wisconsin, Madison, Wisconsin 53792 (United States)

    2011-10-15

    Purpose: The purpose of this work is to explore the usefulness of the gamma passing rate metric for per-patient, pretreatment dose QA and to validate a novel patient-dose/DVH-based method and its accuracy and correlation. Specifically, correlations between: (1) gamma passing rates for three 3D dosimeter detector geometries vs clinically relevant patient DVH-based metrics; (2) Gamma passing rates of whole patient dose grids vs DVH-based metrics, (3) gamma passing rates filtered by region of interest (ROI) vs DVH-based metrics, and (4) the capability of a novel software algorithm that estimates corrected patient Dose-DVH based on conventional phan-tom QA data are analyzed. Methods: Ninety six unique ''imperfect'' step-and-shoot IMRT plans were generated by applying four different types of errors on 24 clinical Head/Neck patients. The 3D patient doses as well as the dose to a cylindrical QA phantom were then recalculated using an error-free beam model to serve as a simulated measurement for comparison. Resulting deviations to the planned vs simulated measured DVH-based metrics were generated, as were gamma passing rates for a variety of difference/distance criteria covering: dose-in-phantom comparisons and dose-in-patient comparisons, with the in-patient results calculated both over the whole grid and per-ROI volume. Finally, patient dose and DVH were predicted using the conventional per-beam planar data as input into a commercial ''planned dose perturbation'' (PDP) algorithm, and the results of these predicted DVH-based metrics were compared to the known values. Results: A range of weak to moderate correlations were found between clinically relevant patient DVH metrics (CTV-D95, parotid D{sub mean}, spinal cord D1cc, and larynx D{sub mean}) and both 3D detector and 3D patient gamma passing rate (3%/3 mm, 2%/2 mm) for dose-in-phantom along with dose-in-patient for both whole patient volume and filtered per-ROI. There was

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

    Science.gov (United States)

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

    2013-10-01

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

  8. Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

    Science.gov (United States)

    Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

    2001-01-01

    The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

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

    Science.gov (United States)

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

    1998-01-01

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

  10. Target and peripheral dose from radiation sector motions accompanying couch repositioning of patient coordinates with the Gamma Knife® Perfexion™

    Science.gov (United States)

    Tran, Tuan-Anh; Wu, Vincent; Malhotra, Harish; Steinman, James P.; Prasad, Dheerendra; Podgorsak, Matthew B.

    2011-01-01

    Background The GammaPlan™ treatment planning system (TPS) does not fully account for shutter dose when multiple shots are required to deliver a patient’s treatment. The unaccounted exposures to the target site and its periphery are measured in this study. The collected data are compared to a similar effect from the Gamma Knife® model 4C. Materials and methods. A stereotactic head frame was attached to a Leksell® 16 cm diameter spherical phantom; using a fiducial-box, CT images of the phantom were acquired and registered in the TPS. Measurements give the relationship of measured dose to the number of repositions with the patient positioning system (PPS) and to the collimator size. An absorbed dose of 10 Gy to the 50% isodose line was prescribed to the target site and all measurements were acquired with an ionization chamber. Results Measured dose increases with frequency of repositioning and with collimator size. As the radiation sectors transition between the beam on and beam off states, the target receives more shutter dose than the periphery. Shutter doses of 3.53±0.04 and 1.59±0.04 cGy/reposition to the target site are observed for the 16 and 8 mm collimators, respectively. The target periphery receives additional dose that varies depending on its position relative to the target. Conclusions The radiation sector motions for the Gamma Knife® Perfexion™ result in an additional dose due to the shutter effect. The magnitude of this exposure is comparable to that measured for the model 4C. PMID:22933947

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

    Science.gov (United States)

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

    2015-02-07

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

  12. 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.

  13. 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.

  14. Determination of differential dose rates in a mixed beta and gamma field using shielded Al{sub 2}O{sub 3}:C: results of Monte Carlo modelling

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M.C. E-mail: marianne.aznar@risoe.dk; Nathan, R.; Murray, A.S.; Boetter-Jensen, L

    2003-10-01

    Mixed beta and gamma heterogeneous radiation fields are found in many circumstances, ranging from retrospective dosimetry to medical therapy treatments. It can be very important to provide a direct measurement of the contribution to dose rate from beta particles and gamma rays separately, especially when heterogeneity is on a scale comparable to the range of beta particles (a few mm). In the retrospective dosimetry of heterogeneous sites, in situ measurement at a point may be the only practical method of measuring the appropriate dose rate. Only if the beta and gamma contributions are measured separately can the appropriate water content and grain attenuation corrections be applied. Such corrections are also essential if the full potential of direct dose rate measurement in reducing the overall uncertainty in a luminescence age to much below 5% is ever to be realised. In this paper we outline the results of our modelling of the most appropriate encapsulation for Al{sub 2}O{sub 3}:C luminescence dosimeters when used to measure the dose rate from natural radiation fields. We consider a configuration where one Al{sub 2}O{sub 3}:C chip of a pair is enclosed in a beta-thin light-tight package (which would allow most of the beta radiation to reach the chip); the other in a beta-thick package (which would absorb most beta radiation, hence leaving the chip to record only gamma radiation). The design of the encapsulation is developed using Monte Carlo simulations, and this approach is also used to investigate the sensitivity of the response to the different beta and gamma contributions from uranium, thorium and potassium sources.

  15. 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.

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

    Science.gov (United States)

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

    2006-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-15

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

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

    Science.gov (United States)

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

    2010-06-01

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

  19. Neutron/gamma dose separation by the multiple-ion-chamber technique

    Energy Technology Data Exchange (ETDEWEB)

    Goetsch, S.J.

    1983-01-01

    Many mixed n/..gamma.. dosimetry systems rely on two dosimeters, one composed of a tissue-equivalent material and the other made from a non-hydrogenous material. The paired chamber technique works well in fields of neutron radiation nearly identical in spectral composition to that in which the dosimeters were calibrated. However, this technique is drastically compromised in phantom due to the degradation of the neutron spectrum. The three-dosimeter technique allows for the fall-off in neutron sensitivity of the two non-hydrogenous dosimeters. Precise and physically meaningful results were obtained with this technique with a D-T source in air and in phantom and with simultaneous D-T neutron and /sup 60/Co gamma ray irradiation in air. The MORSE-CG coupled n/..gamma.. three-dimensional Monte Carlo code was employed to calculate neutron and gamma doses in a water phantom. Gamma doses calculated in phantom with this code were generally lower than corresponding ion chamber measurements. This can be explained by the departure of irradiation conditions from ideal narrow-beam geometry. 97 references.

  20. High gamma irradiation doses and long storage times reduce soybean seed quality

    Directory of Open Access Journals (Sweden)

    Danúbia Aparecida Costa Nobre

    2016-06-01

    Full Text Available High quality seeds are required for soybean production. This study evaluated the effect of gamma irradiation and storage time on seed quality in soybean lines VX04-6828 and VX04-5692. Seeds were gamma irradiated (60Co with 0, 50, 150, and 250 Gy. After the first seed production cycle (M1, the harvested seeds were stored in the laboratory for 0, 2, 4, and 6 months. Moisture content, seed quality (germination rate, dead seeds, and normal and abnormal seedlings, and seed vigor (first germination count, germination index, and seedling length were determined. Data were submitted to analysis of variance for each soybean line using a 4 x 4 factorial design (four storage times x four gamma irradiation doses. Response surfaces were constructed based on the F test significance (p ? 0.05. VX04-5692 seeds were more sensitive to gamma radiation than were VX04-6828 seeds. Soybean seed quality was highest in M2 seeds derived from seeds irradiated with less than 100 Gy and stored for up to two months. High gamma irradiation doses and long storage times reduced soybean seed quality.

  1. Dose profile monitoring with carbon ions by means of prompt-gamma measurements

    Energy Technology Data Exchange (ETDEWEB)

    Testa, E. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France)], E-mail: e.testa@ipnl.in2p3.fr; Bajard, M.; Chevallier, M.; Dauvergne, D.; Le Foulher, F. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France); Freud, N.; Letang, J.M. [Institut National des Sciences Appliquees de Lyon, Laboratoire de Controle Non-Destructif par Rayonnements Ionisants (France); Poizat, J.C.; Ray, C.; Testa, M. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France)

    2009-03-15

    A key point in the quality control of ion therapy is real-time monitoring and imaging of the dose delivered to the patient. Among the possible signals that can be used to make such a monitoring, prompt gamma-rays issued from nuclear fragmentation are possible candidates, provided the correlation between the emission profile and the primary beam range can be established. By means of simultaneous energy and time-of-flight discrimination, we could measure the longitudinal profile of the prompt gamma-rays emitted by 73 MeV/u carbon ions stopping inside a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered gamma rays, and to find a good correlation between the prompt-gamma profile and the ion range. This profile was studied as a function of the observation angle. By extrapolating our results to higher energies and realistic detection efficiencies, we showed that prompt gamma-ray measurements make it feasible to control in real time the longitudinal dose during ion therapy treatments.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-15

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

  3. Effects of high dose gamma irradiation on ITO thin film properties

    Energy Technology Data Exchange (ETDEWEB)

    Alyamani, A. [National Nanotechnology Center, King Abdul-Aziz City for Science and Technology (KACST), Riyadh (Saudi Arabia); Mustapha, N., E-mail: nazirmustapha@hotmail.com [Dept. of Physics, College of Sciences, Al Imam Mohammad Ibn Saud Islamic University, P.O. Box 90950, Riyadh 11623 (Saudi Arabia)

    2016-07-29

    Transparent thin-film Indium Tin Oxides (ITO) were prepared on 0.7 mm thick glass substrates using a pulsed laser deposition (PLD) process with average thickness of 150 nm. The samples were then exposed to high gamma γ radiation doses by {sup 60}Co radioisotope. The films have been irradiated by performing exposure cycles up to 250 kGy total doses at room temperature. The surface structures before and after irradiation were analysed by x-ray diffraction. Atomic Force Microscopy (AFM) was performed on all samples before and after irradiation to investigate any change in the grain sizes, and also in the roughness of the ITO surface. We investigated the influence of γ irradiation on the spectra of transmittance T, in the ultraviolet-visible-near infrared spectrum using spectrophotometer measurements. Energy band gap E{sub g} was then calculated from the optical spectra for all ITO films. It was found that the optical band gap values decreased as the radiation dose was increased. To compare the effect of the irradiation on refractive index n and extinction coefficient k properties, additional measurements were done on the ITO samples before and after gamma irradiation using an ellipsometer. The optical constants n and k increased by increasing the irradiation doses. Electrical properties such as resistivity and sheet resistance were measured using the four-point probe method. The good optical, electrical and morphological properties maintained by the ITO films even after being exposed to high gamma irradiation doses, made them very favourable to be used as anodes for solar cells and as protective coatings in space windows. - Highlights: • Indium Tin Oxide (ITO) thin films were deposited by pulsed laser deposition. • Effects of Gamma irradiation were investigated. • Changes of optical transmission and electrical properties of ITO films were studied. • Intensity of the diffraction peaks and the film's structure changed with increasing irradiation doses.

  4. Influence of dose on particle size of colloidal silver nanoparticles synthesized by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Naghavi, Kazem, E-mail: Kazem.naghavi@gmail.co [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia); Saion, Elias [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia); Rezaee, Khadijeh [Department of Nuclear Engineering, Faculty of Modern Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Yunus, Wan Mahmood Mat [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia)

    2010-12-15

    Colloidal silver nanoparticles were synthesized by {gamma}-irradiation-induced reduction method of an aqueous solution containing silver nitrate as a precursor in various concentrations between 7.40x10{sup -4} and 1.84x10{sup -3} M, polyvinyl pyrrolidone for capping colloidal nanoparticles, isopropanol as radical scavenger of hydroxyl radicals and deionised water as a solvent. The irradiations were carried out in a {sup 60}Co {gamma} source chamber at doses up to 70 kGy. The optical absorption spectra were measured using UV-vis spectrophotometer and used to study the particle distribution and electronic structure of silver nanoparticles. As the radiation dose increases from 10 to 70 kGy, the absorption intensity increases with increasing dose. The absorption peak {lambda}{sub max} blue shifted from 410 to 403 nm correspond to the increase of absorption conduction electron energy from 3.02 to 3.08 eV, indicating the particle size decreases with increasing dose. The particle size was determined by photon cross correlation spectroscopy and the results showed that the particle diameter decreases exponentially with the increase of dose. The transmission electron microscopy images were taken at doses of 20 and 60 kGy and the results confirmed that as the dose increases the diameter of colloidal silver nanoparticle decreases and the particle distribution increases.

  5. Simulation of radioactive plume gamma dose over a complex terrain using Lagrangian particle dispersion model.

    Science.gov (United States)

    Rakesh, P T; Venkatesan, R; Hedde, Thierry; Roubin, Pierre; Baskaran, R; Venkatraman, B

    2015-07-01

    FLEXPART-WRF is a versatile model for the simulation of plume dispersion over a complex terrain in a mesoscale region. This study deals with its application to the dispersion of a hypothetical air borne gaseous radioactivity over a topographically complex nuclear site in southeastern France. A computational method for calculating plume gamma dose to the ground level receptor is introduced in FLEXPART using the point kernel method. Comparison with another similar dose computing code SPEEDI is carried out. In SPEEDI the dose is calculated for specific grid sizes, the lowest available being 250 m, whereas in FLEXPART it is grid independent. Spatial distribution of dose by both the models is analyzed. Due to the ability of FLEXPART to utilize the spatio-temporal variability of meteorological variables as input, particularly the height of the PBL, the simulated dose values were higher than SPEEDI estimates. The FLEXPART-WRF in combination with point kernel dose module gives a more realistic picture of plume gamma dose distribution in a complex terrain, a situation likely under accidental release of radioactivity in a mesoscale range.

  6. Dosimetric effects of Onyx embolization on Gamma Knife arteriovenous malformation dose distributions.

    Science.gov (United States)

    Schlesinger, David J; Nordström, Håkan; Lundin, Anders; Xu, Zhiyuan; Sheehan, Jason P

    2016-12-01

    OBJECTIVE Patients with arteriovenous malformations (AVMs) treated with Gamma Knife radiosurgery (GKRS) subsequent to embolization suffer from elevated local failure rates and differences in adverse radiation effects. Onyx is a common embolic material for AVMs. Onyx is formulated with tantalum, a high atomic number (Z = 73) element that has been investigated as a source of dosimetric uncertainty contributing to the less favorable clinical results. However, prior studies have not modeled the complicated anatomical and beam geometries characteristic of GKRS. This study investigated the magnitude of dose perturbation that can occur due to Onyx embolization using clinically realistic anatomical and Gamma Knife beam models. METHODS Leksell GammaPlan (LGP) was used to segment the AVM nidus and areas of Onyx from postcontrast stereotactic MRI for 7 patients treated with GKRS postembolization. The resulting contours, skull surface, and clinically selected dose distributions were exported from LGP in DICOM-RT (Digital Imaging and Communications in Medicine-radiotherapy) format. Isocenter locations and dwell times were recorded from the LGP database. Contours were converted into 3D mesh representations using commercial and in-house mesh-editing software. The resulting data were imported into a Monte Carlo (MC) dose calculation engine (Pegasos, Elekta Instruments AB) with a beam geometry for the Gamma Knife Perfexion. The MC-predicted dose distributions were calculated with Onyx assigned manufacturer-reported physical constants (MC-Onyx), and then compared with corresponding distributions in which Onyx was reassigned constants for water (MC-water). Differences in dose metrics were determined, including minimum, maximum, and mean dose to the AVM nidus; selectivity index; and target coverage. Combined differences in dose magnitude and distance to agreement were calculated as 3D Gamma analysis passing rates using tolerance criteria of 0.5%/0.5 mm, 1.0%/1.0 mm, and 3.0%/3.0 mm

  7. Cytogenetic dose-response in vitro for biological dosimetry after exposure to high doses of gamma-rays.

    Science.gov (United States)

    Vinnikov, Volodymyr A; Maznyk, Nataliya A

    2013-04-01

    The dose response for dicentrics plus centric rings and total unstable chromosome-type aberrations was studied in the first mitoses of cultured human peripheral blood lymphocytes irradiated in vitro to doses of ∼2, 4, 6, 8, 10, 16 and 20 Gy of acute (60)Со gamma-rays. A dose-dependent increase of aberration yield was accompanied by a tendency to the underdispersion of dicentrics and centric rings among cells distributions compared with Poisson statistics at doses ≥6 Gy. The formal fitting of the data to a linear-quadratic model resulted in an equation with the linear and quadratic coefficients ranged 0.098-0.129×cell(-1)×Gy(-1) and 0.039-0.034×cell(-1)×Gy(-2), respectively, depending on the fitting method. The actual radiation-induced aberration yield was markedly lower than expected from a calibration curve, generated earlier within a lower dose range. Interlaboratory variations in reported dicentric yields induced by medium-to-high radiation doses in vitro are discussed.

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

    Directory of Open Access Journals (Sweden)

    A. R. Talaeipour

    2007-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L [UCSF Comprehensive Cancer Center, San Francisco, CA (United States)

    2015-06-15

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

  10. MCz diode response as a high-dose gamma radiation dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, F. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP, Caixa Postal 11049 - 05422 970 Sao Paulo/SP (Brazil); Goncalves, J.A.C. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP, Caixa Postal 11049 - 05422 970 Sao Paulo/SP (Brazil); Depto. de Fisica, Pontificia Universidade Catolica de Sao Paulo-PUC/SP, Rua Marques de Paranagua no 111-01303 050 Sao Paulo/SP (Brazil); Khoury, H.J. [Nuclear Energy Department, Universidade Federal de Pernambuco-UFPE, Av. Prof. Luiz Freire no 1000-50740 540 Recife/PE (Brazil); Napolitano, C.M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP, Caixa Postal 11049 - 05422 970 Sao Paulo/SP (Brazil); Haerkoenen, J. [Helsinki Institute of Physics-HIP, University of Helsinki, 00014 Helsinki (Finland); Bueno, C.C. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP, Caixa Postal 11049 - 05422 970 Sao Paulo/SP (Brazil); Depto. de Fisica, Pontificia Universidade Catolica de Sao Paulo-PUC/SP, Rua Marques de Paranagua no 111-01303 050 Sao Paulo/SP (Brazil)], E-mail: ccbueno@ipen.br

    2008-02-15

    This work presents the preliminary results obtained with a high-resistivity magnetic Czochralski (MCz) silicon diode processed at the Helsinki Institute of Physics as a high-dose gamma dosimeter in radiation processing. The irradiation was performed using a {sup 60}Co source (Gammacell 220, MDS Nordion) within total doses from 100 Gy up to 3 kGy at a dose rate of 3 kGy/h. In this interval, the dosimetric response of the diode is linear with a correlation coefficient (r{sup 2}) higher than 0.993. However, without any irradiation procedure, the device showed a small sensitivity dependence on the accumulated dose. For total dose of 3 kGy, the observed decrease was about 2%. To clarify the origin of this possible radiation damage effect, some studies are under way.

  11. Does the pretherapeutic tumor SUV in 68Ga DOTATOC PET predict the absorbed dose of 177Lu octreotate?

    Science.gov (United States)

    Ezziddin, Samer; Lohmar, Jonas; Yong-Hing, Charlotte J; Sabet, Amir; Ahmadzadehfar, Hojjat; Kukuk, Guido; Biersack, Hans-Jürgen; Guhlke, Stefan; Reichmann, Karl

    2012-06-01

    Selection of candidates for peptide receptor radionuclide therapy (PRRT) is increasingly based on receptor positron emission tomography (PET) imaging, including the common tracer 68Ga DOTATOC. However, no studies have yet compared standardized uptake values (SUVs) and absorbed doses in this field. We retrospectively analyzed a consecutive cohort of 21 patients with 61 evaluable tumor lesions undergoing both pretherapeutic 68Ga DOTATOC-PET/CT (Biograph Duo [Siemens Medical Solutions, Erlangen, Germany]; PET acquisition, 75.3 ± 15.4 minutes postinjection; 117.3 ± 33.9 MBq 68Ga DOTATOC) and PRRT with Lu octreotate (7.47 ± 1.39 GBq; intratherapeutic tumor dosimetry with serial whole-body scans; 1, 2, and 4 days postinjection) at our institution. SUVs were compared with the tumor-absorbed doses per injected activity (D/A0) of the subsequent first treatment cycle. The correlation of SUV and D/A0 was r = 0.72 (SUVmean) and r = 0.71 (SUVmax), both P 15; SUVmax >25) resulted in high D/A0 (>10 Gy/GBq) in 66.7% to 70.8% and low D/A0 (<5 Gy/GBq) in only 8.3% to 12.5% on subsequent PRRT. The mentioned low D/A0 range, on the other hand, was achieved by all lesions with SUVmean <7 or SUVmax <9. Somatostatin receptor PET imaging may predict tumor-absorbed doses. The ability to indicate insufficient target irradiation by a low SUV could aid in selection of appropriate candidates for PRRT. However, larger series are needed to confirm and validate these initial findings.

  12. Measurement of natural radioactivity in Jordanian building materials and their contribution to the public indoor gamma dose rate.

    Science.gov (United States)

    Sharaf, J M; Hamideen, M S

    2013-10-01

    This study is undertaken to determine the activity concentration of (226)Ra, (232)Th and (40)K in samples of commonly used building materials in Jordan. Samples of seven different materials were collected from construction sites and local agencies supplying raw construction materials and analyzed using a HPGe gamma-ray spectrometer, taking into account self-attenuation in bulk samples. The average specific activity concentrations of (226)Ra, (232)Th, and (40)K ranged from 2.84 to 41.52, 0.78 to 58.42. and 3.74 to 897 Bq/kg, respectively. All the samples had radium equivalent activities well below the limit of 370 Bq/kg set by the Organization for Economic Cooperation and Development (OECD, 1979). External and internal hazard indices, absorbed dose and annual effective dose rate associated with the radionuclides of interest were calculated and compared with the international legislation and guidance. In general, most of the activities did not exceed the recommended international limits, except for granite and ceramic samples which are usually used as secondary building materials in Jordan.

  13. Effect of high gamma-doses in the sensitization of natural quartz for thermoluminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Khoury, H.J.; Guzzo, P.L.; Brito, S.B. [Universidade Federal de Pernambuco, 50740-540 Recife PE (Brazil)

    2006-07-01

    Sensitization is an important effect in radiation dosimetry using thermoluminescent (TL materials where the enhancement of sensitivity is a desirable feature. Until known, the investigation of sensitization in quartz has been restricted to its first glow peak appearing around 110 C. In addition, the sensitization process has been essentially produced by heat-treatments in powdered quartz. The aim of this study is to investigate the sensitization process in the second glow peak of crystalline quartz using high doses of gamma irradiation. For this, five lots of samples were prepared from quartz single crystals issued from different geologies in Brazil. Chips of 5 x 5 x 1 mm{sup 3} (60 mg) were cut and lapped parallel to the (0001) plane. The specimens were initially irradiated with doses of gamma radiation of {sup 137} Cs in the range of 10 mGy to 10 Gy in order to determine its TL response curve. After that, the specimens were submitted to successive high doses of gamma-irradiation with {sup 60} Co from 25 kGy to 350 kGy. After each irradiation, the TL response curves to gamma radiation of {sup 137} Cs were determined for each quartz lot irradiated in the range of 2 to 20 mGy. The TL measurements were carried out with a 2800M Victoreen reader using the step mode. The step parameters were set in 10 s from 30 to 160 C (first region) and in 20 s from 160 to 320 C (second region). The absolute TL signal used to obtain the calibration curves represented the sum of electric charges under the glow peak appearing in the second region. The results showed that the TL response of the quartz studied increased with the dose sensitization, so that the TL response for 10mGy of {sup 137} Cs radiation varied from 0.05 nC/mg for the quartz without sensitization to 10 nC/mg after a sensitization with 50 kGy of gamma radiation of {sup 60} Co. The effect of sensitization with high doses of gamma irradiation was clearly observed for three quartz lots and it was observed that the high

  14. 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.

  15. 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)

  16. Characterizing low dose and dose rate effects in rodent and human neural stem cells exposed to proton and gamma irradiation

    Directory of Open Access Journals (Sweden)

    Bertrand P. Tseng

    2013-01-01

    Full Text Available Past work has shown that exposure to gamma rays and protons elicit a persistent oxidative stress in rodent and human neural stem cells (hNSCs. We have now adapted these studies to more realistic exposure scenarios in space, using lower doses and dose rates of these radiation modalities, to further elucidate the role of radiation-induced oxidative stress in these cells. Rodent neural stem and precursor cells grown as neurospheres and human neural stem cells grown as monolayers were subjected to acute and multi-dosing paradigms at differing dose rates and analyzed for changes in reactive oxygen species (ROS, reactive nitrogen species (RNS, nitric oxide and superoxide for 2 days after irradiation. While acute exposures led to significant changes in both cell types, hNSCs in particular, exhibited marked and significant elevations in radiation-induced oxidative stress. Elevated oxidative stress was more significant in hNSCs as opposed to their rodent counterparts, and hNSCs were significantly more sensitive to low dose exposures in terms of survival. Combinations of protons and γ-rays delivered as lower priming or higher challenge doses elicited radioadaptive changes that were associated with improved survival, but in general, only under conditions where the levels of reactive species were suppressed compared to cells irradiated acutely. Protective radioadaptive effects on survival were eliminated in the presence of the antioxidant N-acetylcysteine, suggesting further that radiation-induced oxidative stress could activate pro-survival signaling pathways that were sensitive to redox state. Data corroborates much of our past work and shows that low dose and dose rate exposures elicit significant changes in oxidative stress that have functional consequences on survival.

  17. Dose-rate effects for apoptosis and micronucleus formation in gamma-irradiated human lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Boreham, D.R.; Dolling, J.-A.; Maves, S.R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Siwarungsun, N. [Chulalongkorn Univ., Bangkok (Thailand); Mitchel, R.E.J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2000-07-01

    We have compared dose-rate effects for {gamma}-radiation-induced apoptosis and micronucleus formation in human lymphocytes. Long-term assessment of individual radiation-induced apoptosis showed little intraindividual variation but significant interindividual variation. The effectiveness of radiation exposure to cause apoptosis or micronucleus formation was reduced by low-dose-rate exposures, but the reduction was apparent at different dose rates for these two end points. Micronucleus formation showed a dose-rate effect when the dose rate was lowered to 0.29 cGy/min, but there was no accompanying cell cycle delay. A further increase in the dose-rate effect was seen at 0.15 cGy/min, but was now accompanied by cell cycle delay. There was no dose-rate effect for the induction of apoptosis until the dose rate was reduced to 0.15 cGy/min, indicating that the mechanisms or signals for processing radiation-induced lesions for these two end points must be different at least in part. There appear to be two mechanisms that contribute to the dose-rate effect for micronucleus formation. One of these does not affect binucleate cell frequency and occurs at dose rates higher than that required to produce a dose-rate effect for apoptosis, and one affects binucleate cell frequency, induced only at the very low dose rate which coincidentally produces a dose-rate effect for apoptosis. Since the dose rate at which cells showed reduced apoptosis as well as a further reduction in micronucleus formation was very low, we conclude that the processing of the radiation-induced lesions that induce apoptosis, and some micronuclei, is very slow in quiescent and PHA-stimulated lymphocytes, respectively. (author)

  18. Dust-to-metal ratios in Damped Lyman-alpha absorbers: Fresh clues to the origins of dust and optical extinction towards gamma-ray bursts

    CERN Document Server

    De Cia, A; Savaglio, S; Schady, P; Vreeswijk, P M

    2013-01-01

    Motivated by the anomalous dust-to-metal ratios (DTM) derived in the literature for gamma-ray burst (GRB) damped Ly-alpha absorbers (DLAs), we measure these ratios using the dust-depletion pattern observed in UV/optical afterglow spectra, associated with the interstellar medium (ISM) at the GRB host-galaxy redshifts. Our sample consists of 20 GRB absorbers and a comparison sample of 72 QSO-DLAs, overall at redshift 1.2 14.7, above which several QSO-DLAs reveal H2, making GRB-DLAs promising candidates for molecular research.

  19. Effect of low dose gamma irradiation on plant and grain nutrition of wheat

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Bhupinder, E-mail: bhupindersinghiari@yahoo.co [Nuclear Research Laboratory, Indian Agricultural Research Institute, New Delhi 110 012 (India); Datta, Partha Sarathi [Nuclear Research Laboratory, Indian Agricultural Research Institute, New Delhi 110 012 (India)

    2010-08-15

    We recently reported the use of low dose gamma irradiation to improve plant vigor, grain development and yield attributes of wheat (). Further, we report here the results of a field experiment conducted to assess the effect of gamma irradiation at 0, 0.01, 0.03, 0.05, 0.07 and 0.1 kGy on flag leaf area, stomatal conductance, transpiration and photosynthetic rate and plant and grain nutritional quality. Gamma irradiation improved plant nutrition but did not improve the nutritional quality of grains particularly relating to micronutrients. Grain carotene, a precursor for vitamin A, was higher in irradiated grains. Low grain micronutrients seem to be caused by a limitation in the source to sink nutrient translocation rather than in the nutrient uptake capacity of the plant root.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-15

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

  1. 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)

  2. External gamma-ray dose rate and radon concentration in indoor environments covered with Brazilian granites

    Energy Technology Data Exchange (ETDEWEB)

    Anjos, R.M., E-mail: meigikos@if.uff.br [LARA - Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (Brazil); Juri Ayub, J. [LARA - Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (Brazil); GEA-Instituto de Matematica Aplicada San Luis (IMASL), Universidad Nacional de San Luis, Consejo Nacional de Investigaciones Cientificas y Tecnicas, CCT-San Luis, Ej. de los Andes 950, D5700HHW San Luis (Argentina); Cid, A.S.; Cardoso, R.; Lacerda, T. [LARA - Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (Brazil)

    2011-11-15

    Health hazard from natural radioactivity in Brazilian granites, covering the walls and floor in a typical dwelling room, was assessed by indirect methods to predict external gamma-ray dose rates and radon concentrations. The gamma-ray dose rate was estimated by a Monte Carlo simulation method and validated by in-situ measurements with a NaI spectrometer. Activity concentrations of {sup 232}Th, {sup 226}Ra, and {sup 40}K in an extensive selection of Brazilian commercial granite samples measured by using gamma-ray spectrometry were found to be 4.5-450 Bq kg{sup -1}, 4.9-160 Bq kg{sup -1} and 190-2029 Bq kg{sup -1}, respectively. The maximum external gamma-ray dose rate from floor and walls covered with the Brazilian granites in the typical dwelling room (5.0 m x 4.0 m area, 2.8 m height) was found to be 120 nGy h{sup -1}, which is comparable with the average worldwide exposure to external terrestrial radiation of 80 nGy h{sup -1} due to natural sources, proposed by United Nations Scientific Committee on the Effects of Atomic Radiation. Radon concentrations in the room were also estimated by a simple mass balance equation and exhalation rates calculated from the measured values of {sup 226}Ra concentrations and the material properties. The results showed that the radon concentration in the room ventilated adequately (0.5 h{sup -1}) will be lower than 100 Bq m{sup -3}, value recommended as a reference level by the World Health Organization. - Highlights: > We used indirect methods to predict external gamma dose rate and radon concentration. > The gamma-ray dose rate was estimated by a Monte Carlo simulation method. > The results were validated by in-situ measurements with a NaI spectrometer. > Radon concentrations in the room were estimated by a simple mass balance equation. > Radon concentration in the room ventilated adequately will be lower than 100 Bq m{sup -3}.

  3. Verification of dose profiles generated by the convolution algorithm of the gamma knife(®) radiosurgery planning system.

    Science.gov (United States)

    Chung, Hyun-Tai; Park, Jeong-Hoon; Chun, Kook Jin

    2017-09-01

    A convolution algorithm that takes into account electron-density inhomogeneity was recently introduced to calculate dose distributions for the Gamma Knife (GK) Perfexion™ treatment planning program. The accuracies of the dose distributions computed using the convolution method were assessed using an anthropomorphic phantom and film dosimetry. Absorbed-dose distributions inside a phantom (CIRS Radiosurgery Head Phantom, Model 605) were calculated using the convolution method of the GK treatment-planning software (Leksell Gamma Plan(®) version 10.1; LGP) for various combinations of collimator size, location, direction of calculation plane, and number of shots. Computed tomography (CT) images of the phantom and a data set of CT number versus electron density were provided to the LGP. Calculated distributions were exported as digital-image communications in medicine-radiation therapy (DICOM-RT) files. Three types of radiochromic film (GafChromic(®) MD-V2-55, MD-V3, and EBT2) were irradiated inside the phantom using GK Perfexion™. Scanned images of the measured films were processed following standard radiochromic film-handling procedures. For a two-dimensional quantitative evaluation, gamma index pass rates (GIPRs) and normalized agreement-test indices (NATIs) were obtained. Image handling and index calculations were performed using a commercial software package (DoseLab Pro version 6.80). The film-dose calibration data were well fitted with third-order polynomials (R(2)  ≥ 0.9993). The mean GIPR and NATI of the 93 analyzed films were 99.3 ± 1.1% and 0.8 ± 1.3, respectively, using 3%/1.0 mm criteria. The calculated maximum doses were 4.3 ± 1.7% higher than the measured values for the 4 mm single shots and 1.8 ± 0.7% greater than those for the 8 mm single shots, whereas differences of only 0.3 ± 0.9% were observed for the 16 mm single shots. The accuracy of the calculated distribution was not statistically related to the collimator size, number

  4. Study of the Melting Latent Heat of Semicrystalline PVDF applied to High Gamma Dose Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M. [Departamento de Anatomia e Imagem - IMA, Universidade Federal de Minas Gerais, Av. Prof. Alfredo Balena, 190, 30130-100, Belo Horizonte, MG (Brazil); Gual, Maritza R.; Faria, Luiz O. [Centro de Desenvolvimento da Tecnologia Nuclear - CDTN, Av. Antonio Carlos 6627, C.P. 941, 31270-901, Belo Horizonte, MG (Brazil); Lima, Claubia P.B. [Departamento de Engenharia Nuclear - DEN, Universidade Federal de Minas Gerais - UFMG, Av. Antonio Carlos 6627, 31270-970 Belo Horizonte, MG (Brazil)

    2015-07-01

    Poly(vinylidene fluoride) homopolymers [PVDF] homopolymers were irradiated with gamma doses ranging from 0.5 to 2.75 MGy. Differential scanning calorimetry (DSC) and FTIR spectrometry were used in order to study the effects of gamma radiation in the amorphous and crystalline polymer structures. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. The melting latent heat (LM) measured by DSC was used to construct an unambiguous relationship with the delivered dose. Regression analyses revealed that the best mathematical function that fits the experimental calibration curve is a 4-degree polynomial function, with an adjusted Rsquare of 0.99817. (authors)

  5. Effects of low dose gamma radiation on the early growth of red pepper and the resistance to subsquent high dose of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. S.; Baek, M. H.; Kim, D. H.; Lee, Y. K. [KAERI, Taejon (Korea, Republic of); Lee, Y. B. [Chungnam National Univ., Taejon (Korea, Republic of)

    2001-05-01

    Red pepper (capsicum annuum L. cv. Jokwang and cv. Johong) seeds were irradiated with the dose of 0{approx}50 Gy to investigated the effect of the low dose gamma radiation on the early growth and resistance to subsequent high dose of radiation. The effect of the low dose gamma radiation on the early growth and resistance to subsequenct high dose of radiation were enhanced in Johong cultivar but not in Jokwang cultivar. Germination rate and early growth of Johong cultivar were noticeably increased at 4 Gy-, 8 Gy- and 20 Gy irradiation group. Resistance to subsequent high dose of radiation of Johong cultivar were increased at almost all of the low dose irradiation group. Especially it was highest at 4 Gy irradiation group. The carotenoid contents and enzyme activity on the resistance to subsequent high dose of radiation of Johong cultivar were increased at the 4 Gy and 8 Gy irradiation group.

  6. 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

  7. Cytosolic Hsp70/Hsc70 protein expression in lymphocytes exposed to low gamma-ray dose

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares A, E.; Vega C, H.R.; Letechipia de Leon, C. [Unidades Academicas de Estudios Nucleares, UAZ, A.P. 336, 98000 Zacatecas (Mexico)]. E-mail: emanz@cantera.reduaz.mx; Guzman E, L.J. [Unidad Academica de Biologia Experimental, Guadalupe, Zacatecas (Mexico); Garcia T, M. [LIBRA, Centro I and D, Campus Miguel Delibes, Valladolid 47011 (Spain)

    2004-07-01

    The purpose of this study was to evaluate the effect of low gamma ray intensity upon Hsp70 expression in human Iymphocytes. The heat shock proteins (Hsp) family, are a group of proteins present in all living organism, therefore there are highly conserved and are related to adaptation and evolution. At cellular level these proteins acts as chaperones correcting denatured proteins. When a stress agent, such heavy metals, UV, heat, etc. is affecting a cell a response to this aggression is triggered only through over expression of Hsp. Several studies has been carried out in which the cellular effect are observed, mostly of these studies uses large doses, but very few studies are related with low doses. Blood of healthy volunteers was obtained and the Iymphocytes were isolated by ficoll- histopaque gradient. Experimental lots were irradiated in a {sup 137} Cs gamma-ray. Hsp70 expression was found since 0.5 c Gy, indicating a threshold to very low doses of gamma rays. (Author)

  8. Assessment of Annual Effective Dose for Natural Radioactivity of Gamma Emitters in Biscuit Samples in Iraq.

    Science.gov (United States)

    Abojassim, Ali Abid; Al-Alasadi, Lubna A; Shitake, Ahmed R; Al-Tememie, Faeq A; Husain, Afnan A

    2015-09-01

    Biscuits are an important type of food, widely consumed by babies in Iraq and other countries. This work uses gamma spectroscopy to measure the natural radioactivity due to long-lived gamma emitters in children's biscuits; it also estimates radiation hazard indices, that is, the radium equivalent activity, the representative of gamma level index, the internal hazard index, and the annual effective dose in children. Ten samples were collected from the Iraqi market from different countries of origin. The average specific activities for (226)Ra, (232)Th, and (40)K were 9.390, 3.1213, and 214.969 Bq/kg, respectively, but the average of the radium equivalent activity and the internal hazard index were 33.101 Bq/kg and 0.107, respectively. The total average annual effective dose from consumption by adults, children, and infants is estimated to be 0.655, 1.009, and 0.875 mSv, respectively. The values found for specific activity, radiation hazard indices, and annual effective dose in all samples in this study were lower than worldwide median values for all groups; therefore, these values are found to be safe.

  9. Absorbed Dose and Effective Dose for Lung Cancer Image Guided Radiation Therapy(IGRT) using CBCT and 4D-CBCT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Yong; Lee, Woo Suk; Koo, Ki Lae; Kim, Joo Seob; Lee, Sang Hyeon [Dept. of Radiation Oncology, GangNeung Asan Hospital, Gangneung (Korea, Republic of)

    2016-06-15

    To evaluate the results of absorbed and effective doses using CBCT and 4D-CBCT settings for lung cancer. This experimental study. Measurements were performed using a Anderson rando phantom with OSLD(optically stimulated luminescent dosimeters). It was performed computed tomography(Lightspeed GE, USA) in order to express the major organs of the human body. Measurements were obtained a mean value is repeated three times each. Evaluations of effective dose and absorbed dose were performed the CL-IX-Thorax mode and Truebeam-Thorax mode CBCT. Additionally, compared Truebeam-Thorax mode CBCT with Truebeam-Thorax mode 4D-CBCT(Four-dimensional Cone Beam Computed Tomography). Average absorbed dose in the CBCT of CL-IX was measured in lung 2.505cGy, heart 2.595cGy, liver 2.145cGy, stomach 1.934cGy, skin 2.233cGy, in case of Truebeam, It was measured lung 1.725cGy, heart 2.034cGy, liver 1.616cGy, stomach 1.470cGy, skin 1.445cGy. In case of 4D-CBCT, It was measured lung 3.849cGy, heart 4.578cGy, liver 3.497cGy, stomach 3.179cGy, skin 3.319cGy Average effective dose, considered tissue weighting and radiation weighting, in the CBCT of CL-IX was measured lung 2.164mSv, heart 2.241mSVv, liver 0.136mSv, stomach 1.668mSv, skin 0.009mSv, in case of Turebeam, it was measured lung 1.725mSv, heart 1.757mSv, liver 0.102mSv, stomach 1.270mSv, skin 0.005mSv, In case of 4D-CBCT, It was measured lung 3.326mSv, heart 3.952mSv, liver 0.223mSv, stomach 2.747mSv, skin 0.013mSv. As a result, absorbed dose and effective Dose in the CL-IX than Truebeam was higher about 1.3 times and in the 4D-CBCT Truebeam than CBCT of Truebeam was higher about 2.2times However, a large movement of the patient and respiratory gated radiotherapy may be more accurate treatment in 4D-CBCT. Therefore, it will be appropriate to selectively used.

  10. On-site gamma dose rates at the Andreeva Bay shore technical base, northwest Russia.

    Science.gov (United States)

    Reistad, O; Dowdall, M; Standring, W J F; Selnaes, Ø G; Hustveit, S; Steinhusen, F; Sørlie, A

    2008-07-01

    The spent nuclear fuel (SNF) and radioactive waste (RAW) storage facility at Andreeva Bay shore technical base (STB) is one of the largest and most hazardous nuclear legacy sites in northwest Russia. Originally commissioned in the 1960s the facility now stores large amounts of SNF and RAW associated with the Russian Northern Fleet of nuclear powered submarines. The objective of the present study was to map ambient gamma dose rates throughout the facility, in particular at a number of specific sites where SNF and RAW are stored. The data presented here are taken from a Norwegian-Russian collaboration enabling the first publication in the scientific literature of the complete survey of on-site dose rates. Results indicate that elevated gamma dose rates are found primarily at discrete sites within the facility; maximum dose rates of up to 1000 microSv/h close to the ground (0.1m) and up to 3000 microSv/h at 1m above ground were recorded, higher doses at the 1m height being indicative primarily of the presence of contaminated equipment as opposed to ground contamination. Highest dose rates were measured at sites located in the immediate vicinity of buildings used for storing SNF and sites associated with storage of solid and liquid radioactive wastes. Elevated dose rates were also observed near the former channel of a small brook that became heavily contaminated as a result of radioactive leaks from the SNF storage at Building 5 starting in 1982. Isolated patches of elevated dose rates were also observed throughout the STB. A second paper detailing the radioactive soil contamination at the site is published in this issue of Journal of Environmental Radioactivity.

  11. Determination of the dose rate to the center of the irradiation chamber of the Gamma cell 220 AECL; Determinacion de la razon de dosis al centro de la camara de irradiacion del Gammacell 220 AECL

    Energy Technology Data Exchange (ETDEWEB)

    Zuazua G, M.P

    1991-11-15

    To determine the dose rate at the center of the irradiation chamber of the Gamma cell 220 AECL, two different spectrophotometers for to measure the absorbency of the irradiated dosemeters were used. In the first one dosimetry, the absorbency of the irradiated Fricke solution was read in the Varian-UV-visible spectrophotometer Series 634 of the Applied Research Management. For the second dosimetry it was used the Shimadzu UV-visible spectrophotometer belonging to the Special Projects Department. The obtained results in this study are presented. (Author)

  12. 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.

  13. Foods for a Mission to Mars: Investigations of Low-Dose Gamma Radiation Effects

    Science.gov (United States)

    Gandolph, J.; Shand, A.; Stoklosa, A.; Ma, A.; Weiss, I.; Alexander, D.; Perchonok, M.; Mauer, L. J.

    2007-01-01

    Food must be safe, nutritious, and acceptable throughout a long duration mission to maintain the health, well-being, and productivity of the astronauts. In addition to a developing a stable pre-packaged food supply, research is required to better understand the ability to convert edible biomass into safe, nutritious, and acceptable food products in a closed system with many restrictions (mass, volume, power, crew time, etc.). An understanding of how storage conditions encountered in a long-term space mission, such as elevated radiation, will impact food quality is also needed. The focus of this project was to contribute to the development of the highest quality food system possible for the duration of a mission, considering shelf-stable extended shelf-life foods, bulk ingredients, and crops to be grown in space. The impacts of space-relevant radiation doses on food, bulk ingredient, and select candidate crop quality and antioxidant capacity were determined. Interestingly, increasing gamma-radiation doses (0 to 1000 Gy) did not always increase dose-related effects in foods. Intermediate radiation doses (10 to 800Gy) often had significantly larger impact on the stability of bulk ingredient oils than higher (1000Gy) radiation doses. Overall, most food, ingredient, and crop systems investigated showed no significant differences between control samples and those treated with 3 Gy of gamma radiation (the upper limit estimated for a mission to Mars). However, this does not mean that all foods will be stable for 3-5 years, nor does it mean that foods are stable to space radiation comprising more than gamma rays.

  14. 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)

  15. 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.

  16. Gamma knife radiosurgery for vestibular schwannomas: results of hearing preservation in relation to the cochlear radiation dose.

    NARCIS (Netherlands)

    Timmer, F.C.A.; Hanssens, P.E.; Haren, A.E. van; Mulder, J.J.S.; Cremers, C.W.R.J.; Beynon, A.J.; Overbeeke, J.J. van; Graamans, K.

    2009-01-01

    OBJECTIVES/HYPOTHESIS: This study was designed to evaluate hearing preservation after gamma knife radiosurgery (GKRS) and to determine the relation between hearing preservation and cochlear radiation dose in patients with a sporadic vestibular schwannoma (VS). METHODS: Prospective study involving

  17. Comparative dosimetry of GammaMed Plus high-dose rate 192 Ir brachytherapy source

    Directory of Open Access Journals (Sweden)

    Patel N

    2010-01-01

    Full Text Available The comparative dosimetry of GammaMed (GM Plus high-dose rate brachytherapy source was performed by an experiment using 0.1-cc thimble ionization chamber and simulation-based study using EGSnrc code. In-water dose measurements were performed with 0.1-cc chamber to derive the radial dose function (r = 0.8 to 20.0 cm and anisotropy function (r = 5.0 cm with polar angle from 10° to 170°. The nonuniformity correction factor for 0.1-cc chamber was applied for in-water measurements at shorter distances from the source. The EGSnrc code was used to derive the dose rate constant (L, radial dose function g L (r and anisotropy function F(r, q of GM Plus source. The dosimetric data derived using EGSnrc code in our study were in very good agreement relative to published data for GM Plus source. The radial dose function up to 12 cm derived from measured dose using 0.1-cc chamber was in agreement within ±3% of data derived by the simulation study.

  18. Study of dose-response and radical decay curves of gamma irradiated norfloxacin using EPR spectroscopy

    Science.gov (United States)

    Sütçü, Kerem; Osmanoǧlu, Yunus Emre

    2017-02-01

    In this study, Electron Paramagnetic Resonance (EPR) spectra of unirradiated and γ-irradiated at doses of 1, 5, 10, 12 and 15 kGy norfloxacin (NOF) were investigated. Before irradiation no EPR signal were observed. After irradiation a weak singlet signal at g = 2.0039 were obtained at room temperature. In order to describe the variation of EPR signal intensity with absorbed radiation dose, several mathematical equations were tried. Increasing irradiation dose up to 15 kGy has increased the signal intensity of the central signal however, no significant changes were observed in g spectroscopic splitting factor. The stability of signal intensity of irradiated NOF was studied over a storage period of 200 days. According to analyses conducted, EPR spectroscopy can be used to distinguish irradiated and unirradiated samples from each other.

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

    Science.gov (United States)

    Mohammadi, Akram; Kinase, Sakae; Saito, Kimiaki

    2012-07-01

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

  20. Effects of gamma irradiation dose rate on microbiological and physical quality of mushrooms (Agaricus bisporus)

    Energy Technology Data Exchange (ETDEWEB)

    Beaulieu, M.; Lacroix, M.; Charbonneau, R.; Laberge, I.; Gagnon, M. (Canadian Irradiation Centre, Laval, PQ (Canada))

    1992-01-01

    The effects of gamma irradiation (2 kGy) and dose rate of irradiation (4.5 and 32.0 kGy/h) on increasing the shelf-life and some quality properties of the mushrooms (Agaricus bisporus) were investigated during storage at 15 deg C and 90% R.H. The retardation of mushroom growth and ageing by reduction of gamma irradiation dose rate (4.5 kGy) was observed by measurements of the cap opening, the stipe increase, the cap diameter, the weight loss and the color of the caps. The color was measured in order to evaluate the lightness with the L value measurement and the color changes were measured in terms of lightness, hue and chroma. The control of fungal and bacterial diseases were also evaluated. The irradiation of mushrooms at both dose rates of irradiation was found to be effective in lowering microorganism counts initially and throughout storage and increased the shelf-life by four days. This study also showed that mushrooms exposed to a lower dose rate (4.5 kGy/h) of irradiation preserve the whiteness and reduce the stripe increase of mushrooms during storage.

  1. Protection of melanized Cryptococcus neoformans from lethal dose gamma irradiation involves changes in melanin's chemical structure and paramagnetism.

    Directory of Open Access Journals (Sweden)

    Abdelahad Khajo

    Full Text Available Certain fungi thrive in highly radioactive environments including the defunct Chernobyl nuclear reactor. Cryptococcus neoformans (C. neoformans, which uses L-3,4-dihydroxyphenylalanine (L-DOPA to produce melanin, was used here to investigate how gamma radiation under aqueous aerobic conditions affects the properties of melanin, with the aim of gaining insight into its radioprotective role. Exposure of melanized fungal cell in aqueous suspensions to doses of γ-radiation capable of killing 50 to 80% of the cells did not lead to a detectable loss of melanin integrity according to EPR spectra of melanin radicals. Moreover, upon UV-visible (Xe-lamp illumination of melanized cells, the increase in radical population was unchanged after γ-irradiation. Gamma-irradiation of frozen cell suspensions and storage of samples for several days at 77 K however, produced melanin modification noted by a reduced radical population and reduced photoresponse. More direct evidence for structural modification of melanin came from the detection of soluble products with absorbance maxima near 260 nm in supernatants collected after γ-irradiation of cells and cell-free melanin. These products, which include thiobarbituric acid (TBA-reactive aldehydes, were also generated by Fenton reagent treatment of cells and cell-free melanin. In an assay of melanin integrity based on the metal (Bi(+3 binding capacity of cells, no detectable loss in binding was detected after γ-irradiation. Our results show that melanin in C. neoformans cells is susceptible to some damage by hydroxyl radical formed in lethal radioactive aqueous environments and serves a protective role in melanized fungi that involves sacrificial breakdown.

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

    Science.gov (United States)

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

    2016-08-20

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

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

    Directory of Open Access Journals (Sweden)

    Shahrokh Naseri

    2014-08-01

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

  4. Characterization of gamma irradiated plasticized carboxymethyl cellulose (CMC)/gum arabic (GA) polymer blends as absorbents for dyestuffs

    Indian Academy of Sciences (India)

    Sayeda M Ibrahim; Issa M Mousaa; Mervat S Ibrahim

    2014-05-01

    Polymer blends based on carboxymethylcellulose (CMC) and gum arabic (GA) were prepared by solution casting method. Glycerol was added to the polymer blend solution as a plasticizer with different ratios (2.5, 5, 10 and 20%). Then, the plasticized blends were exposed to gamma irradiation at different doses (5, 10 and 20 kGy). The physical properties of the plasticized polymer blends were investigated in terms of gel fraction (%) and swelling percent (%). Thermal properties were investigated by TGA. Also, the structure of the plasticized polymer blends was characterized by Fourier transform infrared spectroscopy. Scanning electron microscope was investigated in order to examine the compatibility between two polymers in the blend and also between polymer blend and plasticizer. The prepared plasticized polymer blends were used as an adsorbent for different dyestuffs. The sorption of dyestuffs by the plasticized polymer blend was determined by a method based on spectroscopic analysis. The results showed that the plasticized polymer blend has a high affinity for basic, acid, reactive and direct dyes. The obtained results showed that using glycerol as plasticizer improved the swellability of polymer blend and also the dye uptake (%).

  5. Influence of radiation dose distribution in radiobiological modifications after Gamma Knife radiosurgery

    OpenAIRE

    Massager, Nicolas

    2008-01-01

    La radiochirurgie par Gamma Knife constitue une modalité thérapeutique reconnue de certaines affections cérébrales. Le traitement se base sur l’administration d’un rayonnement focalisé au niveau d’une cible intracrânienne. L’efficacité de ce traitement repose sur la délivrance d’une dose d’irradiation efficace au sein d’un volume-cible associé à la délivrance d’une dose d’irradiation négligeable à l’extérieur de ce même volume-cible. En pratique, la dose d’irradiation administrée à l’intérieu...

  6. Gamma Radiation Measurements and Dose Rates in Commonly Used Building Materials in Cyprus

    CERN Document Server

    Michael, F; Parpottas, Y

    2010-01-01

    A first comprehensive study is presented on radioactivity concentrations and dose rates in 87 commonly used materials, manufactured or imported in Cyprus, for building purposes. The natural radioactivity of K-40, Th-232, U-238 and Ra-226 is determined using high-resolution gamma ray spectroscopy. The respective dose rates and the associated radiological effect indices are also calculated. A comparison of the measured specific activity values with the corresponding world average values shows that most of them are below the world average activity values. The annual indoor effective dose rates received by an individual from three measured imported granites and four measured imported ceramics are found to be higher than the world upper limit value of 1 mSv y-1. Hence, these materials should have a restricted use according to their corresponding calculated activity concentration index values and the related EC 1999 guidelines.

  7. 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...

  8. Gantry orientation effect on the neutron and capture gamma ray dose equivalent at the maze entrance door in radiation therapy

    Directory of Open Access Journals (Sweden)

    Ghiasi Hosein

    2012-01-01

    Full Text Available In the present study, the effect of gantry orientation on the photoneutron and capture gamma dose calculations for maze entrance door was evaluated. A typical radiation therapy room made of ordinary concrete was simulated using MCNPX Monte Carlo code. Gantry rotation was simulated at eight different angles around the isocenter. Both neutron and capture gamma dose vary considerably with gantry angle. The ratios of the maximum to the minimum values for neutron and capture gamma dose equivalents were 1.9 and 1.4, respectively. On the other hand, comparison of the Monte Carlo calculated mean value over all orientations with Monte Carlo calculated neutron and gamma dose showed that the Wu-McGinley method differed by 5% and 2%, respectively. However, for more conservative shielding calculations, factors of 1.6 and 1.3 should be applied to the calculated neutron and capture gamma doses at downward irradiation. Finally, it can be concluded that the gantry angle influences neutron and capture gamma dose at the maze entrance door and it should be taken into account in shielding considerations.

  9. 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

  10. 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.

  11. Avoidance behaviour and anxiety in rats irradiated with a sublethal dose of gamma-rays.

    Science.gov (United States)

    Tomášová, Lenka; Smajda, B; Bona, M

    2011-12-01

    The aim of this study was to assess, whether a sublethal dose of gamma-rays will influence the avoidance behaviour and anxiety in rats and whether the response to radiation depends on time of day of its application. Adult male Wistar rats were tested in elevated plus-maze, in hot plate test and in the light/dark box in 4 regular intervals during a day. After two weeks the animals were irradiated with a whole-body dose 6 Gy of gamma-rays. One day after irradiation the animals were repeatedly tested in the same way, as before irradiation. In the plus-maze test an increased level of anxiety was established. The irradiation significantly decreased the locomotor activity of rats, but the extent of exploratory and comfortable behaviour were not altered. After irradiation, an elevated aversion to the thermal stimulus was observed in the hot plate test. The effects of radiation were more pronounced in the light period of the day, than in the dark one. No significant differences in aversion to light were detected after irradiation. The obtained results indicate, that sublethal doses of ionizing radiation can markedly influence the reactivity of animals to adverse stimuli, their motoric activity and emotional status, as well.

  12. Scattering-absorbing method for the detection of 16.7 MeV high-energy pulse gamma

    Institute of Scientific and Technical Information of China (English)

    Tan Xinjian; Ouyang Xiaoping; Wang Qunshu

    2009-01-01

    Based on theoretical calculation and Monte Carlo simulation, this paper proposes a new method for the diagno-sing of 16.7 MeV high-energy pulse gamma, named "scattering absorption method". The ratio of the sensitivity of high-energy gamma to that of the low-energy background gamma can reach 106 to 108 by this new method. The sensitivity of 16.7 McV high-energy gamma ranges from 10-21 to 10-16 C·cm2. It's better than the traditional method which is based on the magnetic analyzer and Chcrankov detector on some aspects.

  13. Measurements of gamma dose and thermal neutron fluence in phantoms exposed to a BNCT epithermal beam with TLD-700.

    Science.gov (United States)

    Gambarini, G; Magni, D; Regazzoni, V; Borroni, M; Carrara, M; Pignoli, E; Burian, J; Marek, M; Klupak, V; Viererbl, L

    2014-10-01

    Gamma dose and thermal neutron fluence in a phantom exposed to an epithermal neutron beam for boron neutron capture therapy (BNCT) can be measured by means of a single thermoluminescence dosemeter (TLD-700). The method exploits the shape of the glow curve (GC) and requires the gamma-calibration GC (to obtain gamma dose) and the thermal-neutron-calibration GC (to obtain neutron fluence). The method is applicable for BNCT dosimetry in case of epithermal neutron beams from a reactor because, in most irradiation configurations, thermal neutrons give a not negligible contribution to the TLD-700 GC. The thermal neutron calibration is not simple, because of the impossibility of having thermal neutron fields without gamma contamination, but a calibration method is here proposed, strictly bound to the method itself of dose separation.

  14. 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

  15. Determination of the absorbed dose rate to a person exposed to a spent source of {sup 60}Co for radiotherapy; Determinacion de la rapidez de dosis absorbida a una persona expuesta a una fuente gastada de {sup 60}Co para radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, T.; Angeles C, A.; Benitez, J. A.; Ruiz C, M. A., E-mail: teodoro.garcia@inin.gob.mx [ININ, Departamento de Proteccion Radiologica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2016-09-15

    In this work the analysis of absorbed dose rate to a person in made due to the exposure to a spent source of {sup 60}Co of radiotherapy, which has been removed from its shielding clandestinely to sell the shielding as scrap. During the removal of the source of their shielding the people were necessarily exposed to the field of gamma radiation. The activity of the source is considered to be 2595 Ci at the exposure time and to determine the rate of absorbed dose to different organs and the velocity of effective absorbed dose to which the person (s) who manipulated the source of {sup 60}Co were considered three plausible scenarios of manipulation of the source , through modeling with MCNP5. For the execution of the scenarios and the determination of the absorbed doses, two different phantoms are considered. The results obtained for each scenario show that the dose rates to which the people who manipulated the source without the shielding were exposed are extremely high, and in short time the lethal dose is reached. (Author)

  16. Bystander responses in low dose irradiated cells treated with plasma from gamma irradiated blood

    Energy Technology Data Exchange (ETDEWEB)

    Acheva, A; Georgieva, R; Rupova, I; Boteva, R [Laboratory Molecular Radiobiology and Epidemiology, National Centre of Radiobiology and Radiation Protection, 132 Kliment Ohridski blvd, Sofia 1756 (Bulgaria); Lyng, F [Radiation and Environmental Science Center, Dublin Institute of Technology, Kevin st, Dublin 8 (Ireland)], E-mail: anjin_a@mail.bg

    2008-02-01

    There are two specific low-dose radiation-induced responses that have been the focus of radiobiologists' interest in recent years. These are the bystander effect in non-irradiated cells and the adaptive response to a challenge dose after prior low dose irradiation. In the present study we have investigated if plasma from irradiated blood can act as a 'challenge dose' on low dose irradiated reporter epithelial cells (HaCaT cell line). The main aim was to evaluate the overall effect of low dose irradiation (0.05 Gy) of reporter cells and the influence of bystander factors in plasma from 0.5 Gy gamma irradiated blood on these cells. The effects were estimated by clonogenic survival of the reporter cells. We also investigated the involvement of reactive oxygen species (ROS) as potential factors involved in the bystander signaling. Calcium fluxes and mitochondrial membrane potential (MMP) depolarization were also examined as a marker for initiation of apoptosis in the reporter cells. The results show that there are large individual differences in the production of bystander effects and adaptive responses between different donors. These may be due to the specific composition of the donor plasma. The observed effects generally could be divided into two groups: adaptive responses and additive effects. ROS appeared to be involved in the responses of the low dose pretreated reporter cells. In all cases there was a significant decrease in MMP which may be an early event in the apoptotic process. Calcium signaling also appeared to be involved in triggering apoptosis in the low dose pretreated reporter cells. The heterogeneity of the bystander responses makes them difficult to be modulated for medical uses. Specific plasma characteristics that cause these large differences in the responses would need to be identified to make them useful for radiotherapy.

  17. Bystander responses in low dose irradiated cells treated with plasma from gamma irradiated blood

    Science.gov (United States)

    Acheva, A.; Georgieva, R.; Rupova, I.; Boteva, R.; Lyng, F.

    2008-02-01

    There are two specific low-dose radiation-induced responses that have been the focus of radiobiologists' interest in recent years. These are the bystander effect in non-irradiated cells and the adaptive response to a challenge dose after prior low dose irradiation. In the present study we have investigated if plasma from irradiated blood can act as a 'challenge dose' on low dose irradiated reporter epithelial cells (HaCaT cell line). The main aim was to evaluate the overall effect of low dose irradiation (0.05 Gy) of reporter cells and the influence of bystander factors in plasma from 0.5 Gy gamma irradiated blood on these cells. The effects were estimated by clonogenic survival of the reporter cells. We also investigated the involvement of reactive oxygen species (ROS) as potential factors involved in the bystander signaling. Calcium fluxes and mitochondrial membrane potential (MMP) depolarization were also examined as a marker for initiation of apoptosis in the reporter cells. The results show that there are large individual differences in the production of bystander effects and adaptive responses between different donors. These may be due to the specific composition of the donor plasma. The observed effects generally could be divided into two groups: adaptive responses and additive effects. ROS appeared to be involved in the responses of the low dose pretreated reporter cells. In all cases there was a significant decrease in MMP which may be an early event in the apoptotic process. Calcium signaling also appeared to be involved in triggering apoptosis in the low dose pretreated reporter cells. The heterogeneity of the bystander responses makes them difficult to be modulated for medical uses. Specific plasma characteristics that cause these large differences in the responses would need to be identified to make them useful for radiotherapy.

  18. 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

    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......, 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...... dose associated with i.p. administration of (211)At-MX35 F(ab')2. METHODS AND MATERIALS: Patients in clinical remission after salvage chemotherapy for peritoneal recurrence of ovarian cancer underwent i.p. infusion of (211)At-MX35 F(ab')2. Potassium perchlorate was given to block unwanted accumulation...

  19. 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. 

  20. Effect of gamma irradiation at intermediate doses on the performance of reverse osmosis membranes

    Science.gov (United States)

    Combernoux, Nicolas; Labed, Véronique; Schrive, Luc; Wyart, Yvan; Carretier, Emilie; Moulin, Philippe

    2016-07-01

    The goal of this study is to explain the degradation of Polyamide (PA) composite reverse osmosis membrane (RO) in function of the irradiation dose. Irradiations were performed with a gamma 60Co source in wet conditions and under oxygen atmosphere. For different doses of 0.2 and 0.5 MGy with a constant dose rate of 0.5 kGy h-1, RO membranes performances (NaCl retention, permeability) were studied before and after irradiation. ATR-FTIR, ion chromatography and gas chromatography were used to characterize structural modification. Results showed that the permeability of RO membranes irradiated at 0.2 MGy exhibited a small decrease, related to scissions of the PVA coating. However, retention did not change at this dose. At 0.5 MGy, permeability showed a large increase of a factor around 2 and retention began to decrease from 99% to 95%. Chromatography measurements revealed a strong link between permselectivity properties variation, ion leakage and oxygen consumption. Add to ATR-FTIR observations, these results emphasized that the cleavages of amide and ester bonds were observed at 0.5 MGy, more precisely the loss of hydrogen bonds between polyamide chains. By different analysis, modifications of the polysulfone layer occur until a dose of 0.2 MGy.

  1. Degradation and annealing studies on gamma rays irradiated COTS PPD CISs at different dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zujun, E-mail: wangzujun@nint.ac.cn [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Ma, Yingwu [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China); Liu, Jing [School of Materials Science and Engineering, Xiangtan University, Xiangtan, 411105 Hunan (China); Xue, Yuan; He, Baoping; Yao, Zhibin; Huang, Shaoyan; Liu, Minbo; Sheng, Jiangkun [State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, P.O.Box 69-10, Xi’an (China)

    2016-06-01

    The degradation and annealing studies on Colbalt-60 gamma-rays irradiated commercial-off-the-shelf (COTS) pinned photodiode (PPD) CMOS image sensors (CISs) at the various dose rates are presented. The irradiation experiments of COTS PPD CISs are carried out at 0.3, 3.0 and 30.0 rad(Si)/s. The COTS PPD CISs are manufactured using a standard 0.18-μm CMOS technology with four-transistor pixel PPD architecture. The behavior of the tested CISs shows a remarkable degradation after irradiation and differs in the dose rates. The dark current, dark signal non-uniformity (DSNU), random noise, saturation output, signal to noise ratio (SNR), and dynamic range (DR) versus the total ionizing dose (TID) at the various dose rates are investigated. The tendency of dark current, DSNU, and random noise increase and saturation output, SNR, and DR to decrease at 3.0 rad(Si)/s are far greater than those at 0.3 and 30.0 rad(Si)/s. The damage mechanisms caused by TID irradiation at the various dose rates are also analyzed. The annealing tests are carried out at room temperature with unbiased conditions after irradiation.

  2. 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.

  3. Dosis: A computer program for the calculation of absorbed dose in photon and electron beams from ionization measurements in a phantom

    Science.gov (United States)

    Andreo, Pedro

    1983-06-01

    A computer program has been developed to facilitate the calculation of the absorbed dose in photon and electron beams from measurements with an ionization chamber in a phantom. The generalized Bragg-Gray theory, introduced in the latest recommendations of the Nordic Association of Clinical Physics (NACP), is used throughout the code, including more updated parameter values than those included in the NACP protocol. The calibration factor of the ionization chamber in units of absorbed dose in the air of the cavity can be derived for most of the chambers available today by using experimental data or fitted relations to Monte Carlo results.

  4. Gamma spectrum, count rate, and dose rate measurements of the Columbia riverbank from Vernita to Sacajawea

    Energy Technology Data Exchange (ETDEWEB)

    Grande, L.A.

    1966-01-31

    The purpose of this study was to evaluate radiological conditions that exist on the riverbank of the Columbia River. Included was a comparative study of the suitability of three instruments to measure the dose rates. These instruments were a NaI (T1) scintillation counter normally used for aerial monitoring, a bioplastic scintillation counter normally used as a road monitor, and a portable 40 liter ionization chamber normally used to measure very low gamma dose rates. The selection of representative sites for the comparative study was based on an initial GM survey of the general areas in question. Seven sites were studied--from Vernita Ferry Landing above the Hanford project to Sacajawea Park below Pasco.

  5. Open-source hardware and software and web application for gamma dose rate network operation.

    Science.gov (United States)

    Luff, R; Zähringer, M; Harms, W; Bleher, M; Prommer, B; Stöhlker, U

    2014-08-01

    The German Federal Office for Radiation Protection operates a network of about 1800 gamma dose rate stations as a part of the national emergency preparedness plan. Each of the six network centres is capable of operating the network alone. Most of the used hardware and software have been developed in-house under open-source license. Short development cycles and close cooperation between developers and users ensure robustness, transparency and fast maintenance procedures, thus avoiding unnecessary complex solutions. This also reduces the overall costs of the network operation. An easy-to-expand web interface has been developed to make the complete system available to other interested network operators in order to increase cooperation between different countries. The interface is also regularly in use for education during scholarships of trainees supported, e.g. by the 'International Atomic Energy Agency' to operate a local area dose rate monitoring test network.

  6. 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

  7. Terrestrial gamma radiation dose study to determine the baseline for environmental radiological health practices in Melaka state, Malaysia.

    Science.gov (United States)

    Ramli, Ahmad Termizi; Sahrone, Sallehudin; Wagiran, Husin

    2005-12-01

    Environmental terrestrial gamma radiation dose rates were measured throughout Melaka, Malaysia, over a period of two years, with the objective of establishing baseline data on the background radiation level. Results obtained are shown in tabular, graphic and cartographic form. The values of terrestrial gamma radiation dose rate vary significantly over different soil types and for different underlying geological characteristics present in the study area. The values ranged from 54 +/- 5 to 378 +/- 38 nGy h(-1). The highest terrestrial gamma dose rates were measured over soil types of granitic origin and in areas with underlying geological characteristics of an acid intrusive (undifferentiated) type. An isodose map of terrestrial gamma dose rate in Melaka was drawn by using the GIS application 'Arc View'. This was based on data collected using a NaI(Tl) scintillation detector survey meter. The measurements were taken at 542 locations. Three small 'hot spots' were found where the dose rates were more than 350 nGy h(-1). The mean dose rates in the main population areas in the mukims (parishes) of Bukit Katil, Sungai Udang, Batu Berendam, Bukit Baru and Bandar Melaka were 154 +/- 15, 161 +/- 16, 160 +/- 16, 175 +/- 18 and 176 +/- 18 nGy h(-1), respectively. The population-weighted mean dose rate throughout Melaka state is 172 +/- 17 nGy h(-1). This is lower than the geographical mean dose rate of 183 +/- 54 nGy h(-1). The lower value arises from the fact that most of the population lives in the central area of the state where the lithology is dominated by sedimentary rocks consisting of shale, mudstone, phyllite, slate, hornfels, sandstone and schist of Devonian origin which have lower associated dose rates. The mean annual effective dose to the population from outdoor terrestrial gamma radiation was estimated to be 0.21 mSv. This value is higher than the world average of 0.07 mSv.

  8. The maximum tolerated dose of gamma radiation to the optic nerve during γ knife radiosurgery in an animal study.

    Science.gov (United States)

    Deng, Xingli; Yang, Zhiyong; Liu, Ruen; Yi, Meiying; Lei, Deqiang; Wang, Zhi; Zhao, Hongyang

    2013-01-01

    The safety of gamma knife radiosurgery should be considered when treating pituitary adenomas. To determine the maximum tolerated dose of radiation delivered by gamma knife radiosurgery to optic nerves. An animal model designed to establish prolonged balloon compression of the optic chiasm and parasellar region was developed to mimic the optic nerve compression caused by pituitary adenomas. Twenty cats underwent surgery to place a balloon for compression effect and 20 cats in a sham operation group received microsurgery without any treatment. The effects of gamma knife irradiation at 10-13 Gy on normal (sham operation group) and compressed (optic nerve compression group) optic nerves were investigated by pattern visual evoked potential examination and histopathology. Gamma knife radiosurgery at 10 Gy had almost no effect. At 11 Gy, P100 latency was significantly prolonged and P100 amplitude was significantly decreased in compressed optic nerves, but there was little change in the normal optic nerves. Doses of 11 Gy and higher induced significant electrophysiological variations and degeneration of the myelin sheath and axons in both normal and compressed optic nerves. Compressed optic nerves are more sensitive to gamma knife radiosurgery than normal optic nerves. The minimum dose of gamma knife radiosurgery that causes radiation injury in normal optic nerves is 12 Gy; however, the minimum dose is 11 Gy in compressed optic nerves. Copyright © 2013 S. Karger AG, Basel.

  9. 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.

  10. The ferrous ammonium sulfate solid system, as dosemeter for processes at low temperatures and high doses of gamma radiation; El sistema sulfato ferroso amoniacal solido, como dosimetro para procesos a bajas temperaturas y altas dosis de radiacion gamma

    Energy Technology Data Exchange (ETDEWEB)

    Juarez C, J.M.; Ramos B, S.; Negron M, A. [ICN-UNAM, 04510 Mexico D.F. (Mexico)

    2005-07-01

    This paper presents the results obtained from a study of the radiation induced oxidation of crystalline ferrous ammonium sulfate with gamma rays at 295 K, 263 K and 77 K and dose from 0 to 300 kGy. The radiation induced decomposition of ferrous ammonium sulfate has been studied by the dissolution of the irradiated salt in 0,8 N sulfuric acid. The main product is Fe{sup 3+} and molar concentration of ferric ion was determined spectrophotometrically in the UV region at 304 nm. The optical density values showed a linear dependence with dose, indicating that the data obtained might be used to create a calibrating curve. Color in irradiated salt changes from blue to green, yellow and orange according to the absorbed dose. The accuracy and the reproducibility of the system were tested. In addition, some other characteristics make possible the use of this system as a dosimeter, similar to Fricke chemical dosemeter, at low temperatures and high dose. (Author)

  11. Spatial analysis of ambient gamma dose equivalent rate data by means of digital image processing techniques.

    Science.gov (United States)

    Szabó, Katalin Zsuzsanna; Jordan, Gyozo; Petrik, Attila; Horváth, Ákos; Szabó, Csaba

    2017-01-01

    A detailed ambient gamma dose equivalent rate mapping based on field measurements at ground level and at 1 m height was carried out at 142 sites in 80 × 90 km area in Pest County, Hungary. Detailed digital image processing analysis was carried out to identify and characterise spatial features such as outlying points, anomalous zones and linear edges in a smoothed TIN interpolated surface. The applied method proceeds from the simple shaded relief model and digital cross-sections to the more complex gradient magnitude and gradient direction maps, 2nd derivative profile curvature map, relief map and lineament density map. Each map is analysed for statistical characteristics and histogram-based image segmentation is used to delineate areas homogeneous with respect to the parameter values in these maps. Assessment of spatial anisotropy is implemented by 2D autocorrelogram and directional variogram analyses. The identified spatial features are related to underlying geological and tectonic conditions using GIS technology. Results show that detailed digital image processing is efficient in revealing the pattern present in field-measured ambient gamma dose equivalent rates and they are related to regional scale tectonic zones and surface sedimentary lithological conditions in the study area.

  12. Biological radiation dose from secondary particles in a Milky Way gamma-ray burst

    Science.gov (United States)

    Atri, Dimitra; Melott, Adrian L.; Karam, Andrew

    2014-07-01

    Gamma-ray bursts (GRBs) are a class of highly energetic explosions emitting radiation in a very short timescale of a few seconds and with a very narrow opening angle. Although, all GRBs observed so far are extragalactic in origin, there is a high probability of a GRB of galactic origin beaming towards the Earth in the past ~0.5 Gyr. We define the level of catastrophic damage to the biosphere as approximation 100 kJ m-2, based on Thomas et al. (2005a, b). Using results in Melott & Thomas (2011), we estimate the probability of the Earth receiving this fluence from a GRB of any type, as 87% during the last 500 Myr. Such an intense burst of gamma rays would ionize the atmosphere and deplete the ozone (O3) layer. With depleted O3, there will be an increased flux of Solar UVB on the Earth's surface with potentially harmful biological effects. In addition to the atmospheric damage, secondary particles produced by gamma ray-induced showers will reach the surface. Among all secondary particles, muons dominate the ground-level secondary particle flux (99% of the total number of particles) and are potentially of biological significance. Using the Monte Carlo simulation code CORSIKA, we modelled the air showers produced by gamma-ray primaries up to 100 GeV. We found that the number of muons produced by the electromagnetic component of hypothetical galactic GRBs significantly increases the total muon flux. However, since the muon production efficiency is extremely low for photon energies below 100 GeV, and because GRBs radiate strongly for only a very short time, we find that the biological radiation dose from secondary muons is negligible. The main mechanism of biological damage from GRBs is through Solar UVB irradiation from the loss of O3 in the upper atmosphere.

  13. Repeat Gamma-Knife Radiosurgery for Refractory or Recurrent Trigeminal Neuralgia with Consideration About the Optimal Second Dose.

    Science.gov (United States)

    Park, Seong-Cheol; Kwon, Do Hoon; Lee, Do Hee; Lee, Jung Kyo

    2016-02-01

    To investigate adequate radiation doses for repeat Gamma Knife radiosurgery (GKS) for trigeminal neuralgia in our series and meta-analysis. Fourteen patients treated by ipsilateral repeat GKS for trigeminal neuralgia were included. Median age of patients was 65 years (range, 28-78), the median target dose, 140-180). Patients were followed a median of 10.8 months (range, 1-151) after the second gamma-knife surgery. Brainstem dose analysis and vote-counting meta-analysis of 19 studies were performed. After the second gamma-knife radiosurgeries, pain was relieved effectively in 12 patients (86%; Barrow Neurological Institute Pain Intensity Score I-III). Post-gamma-knife radiosurgery trigeminal nerve deficits were mild in 5 patients. No serious anesthesia dolorosa was occurred. The second GKS radiation dose ≤ 60 Gy was significantly associated with worse pain control outcome (P = 0.018 in our series, permutation analysis of variance, and P = 0.009 in the meta-analysis, 2-tailed Fisher's exact test). Cumulative dose ≤ 140-150 Gy was significantly associated with poor pain control outcome (P = 0.033 in our series and P = 0.013 in the meta-analysis, 2-tailed Fisher's exact test). A cumulative brainstem edge dose >12 Gy tended to be associated with trigeminal nerve deficit (P = 0.077). Our study suggests that the second GKS dose is a potentially important factor. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Measurement of in-phantom neutron flux and gamma dose in Tehran research reactor boron neutron capture therapy beam line

    OpenAIRE

    Elham Bavarnegin; Alireza Sadremomtaz; Hossein Khalafi; Yaser Kasesaz

    2016-01-01

    Aim: Determination of in-phantom quality factors of Tehran research reactor (TRR) boron neutron capture therapy (BNCT) beam. Materials and Methods: The doses from thermal neutron reactions with 14N and 10B are calculated by kinetic energy released per unit mass approach, after measuring thermal neutron flux using neutron activation technique. Gamma dose is measured using TLD-700 dosimeter. Results: Different dose components have been measured in a head phantom which has been designed an...

  15. 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.

  16. Dose-response relationship of {gamma}-H2AX foci induction in human lymphocytes after X-rays exposure

    Energy Technology Data Exchange (ETDEWEB)

    Mandina, Tania [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Roch-Lefevre, Sandrine H.; Voisin, Pascale [Institut de Radioprotection et de Surete Nucleaire (IRSN), DRPH, SRBE, LDB, BP17, 92262 Fontenay-aux-Roses (France); Gonzalez, Jorge E.; Lamadrid, Ana I.; Romero, Ivonne [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Garcia, Omar, E-mail: omar@cphr.edu.cu [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41y 47 Miramar, AP 6195 C. Habana (Cuba); Voisin, Philippe; Roy, Laurence [Institut de Radioprotection et de Surete Nucleaire (IRSN), DRPH, SRBE, LDB, BP17, 92262 Fontenay-aux-Roses (France)

    2011-09-15

    Biological dosimeters are recommended for dose estimation in case of human overexposure to ionising radiation. Rapid measurement of {gamma}-H2AX foci as a marker of DNA double-strand breaks (DSB) induction has been recently tested with this purpose. Here we reported a dose-response relationship after X-ray irradiation at different times post-exposure. Blood samples were obtained from several healthy donors and exposed to doses between 0 and 2 Gy. After irradiation, blood samples were incubated at 37 deg. C during 0.5 h, 5 h, and 8 h. Scoring of cells and {gamma}-H2AX foci was performed by software. The dose-response curves for different incubation times were as follows: Y{sub (0.5h)} = 11.66D + 0.15 (R{sup 2} = 0.99), Y{sub (5h)} = 2.44D + 0.15 (R{sup 2} = 0.99), Y{sub (8h)} = 1.57D + 0.22 (R{sup 2} = 0.99). At 0.5 h post-exposure, the dose-response relationship for X-irradiated lymphocytes was similar to the one obtained after gamma-irradiation using the same protocol. On the other hand, the results were not similar after 8 h due to different kinetics after gamma- and X-irradiation. Our results confirm the possibilities of using {gamma}-H2AX foci method for dose estimation in a period from 0.5 h up to 8 h post X-irradiation and support the hypothesis of differences in {gamma}-H2AX foci kinetics after gamma- and X-irradiation in vitro.

  17. Caffeine protects mice against whole-body lethal dose of {gamma}-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    George, K.C.; Hebbar, S.A.; Kale, S.P.; Kesavan, P.C. [Biosciences Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    1999-06-01

    Administration of caffeine (1,3,7-trimethylxanthine), a major component of coffee, to Swiss mice at doses of 80 or 100 mg/kg body weight 60 min prior to whole-body lethal dose of {gamma}-irradiation (7.5 Gy) resulted in the survival of 70 and 63% of animals, respectively, at the above doses in contrast to absolutely no survivors (LD-100/25 days) in the group exposed to radiation alone. Pre-treatment with a lower concentration of caffeine (50 mg/kg) did not confer any radioprotection. The protection exerted by caffeine (80 mg/kg), however, was reduced from 70 to 50% if administered 30 min prior to irradiation. The trend statistics reveal that a dose of 80 mg/kg administered 60 min before whole-body exposure to 7.5 Gy is optimal for maximal radioprotection. However, caffeine (80 mg/kg) administered within 3 min after irradiation offered no protection. While there is documentation in the literature that caffeine is an antioxidant and radioprotector against the toxic pathway of radiation damage in a wide range of cells and organisms, this is the first report demonstrating unequivocally its potent radioprotective action in terms of survival of lethally whole-body irradiated mice. (author)

  18. Three years of seasonal dose assessment from outdoors gamma exposure in Sao Paulo city, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Janete C.G.G.; Sanches, Matias P.; Betti, Flavio; Pecequilo, Brigitte R.S., E-mail: janetegc@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Measurements of external (outdoors) gamma exposure from natural background radiation have been used to estimate the average annual doses in Sao Paulo city. Twelve monitoring stations were placed in different regions of the town including both urban (where building materials are present) and outskirts areas. Seasonally surveys observing the four seasons from 2008 to 2010 have been carried out. The data were drawn from a 3-month sampling using the thermoluminescent dosimetry. The effective doses values are quite similar (slightly higher during the winter), so it can be considered that these results are not under significant influence (or variability) of seasonal environmental conditions like temperature, wind or rain. Dose values over the three years period, from Vila Carrao district, exclusively an urban location with mostly no green areas, present the highest values, while the lower values were always obtained for Tucuruvi district, near the biggest urban forest, Parque Estadual da Cantareira. Over the assessed period, the mean of the average annual effective doses was 1.3 {+-} 0.1 mSv.y{sup -1}. For the same period, the average annual background from nuclear and radioactive facility at IPEN was 0.75 {+-} 0.12 mSv.y{sup -1}. (author)

  19. 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

  20. 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

  1. Radioactivity measurements in soils surrounding four coal-fired power plants in Serbia by gamma-ray spectrometry and estimated dose

    Directory of Open Access Journals (Sweden)

    Vukašinović Ivana Ž.

    2014-01-01

    Full Text Available The study of spatial distribution of activity concentration of 238U, 226Ra, 210Pb, 232Th, 40K, and 137Cs radionuclides in the surface soil samples (n = 42 collected in the vicinity of four coal-fired power plants in Serbia is presented. Radioactivity measurements in soils performed by gamma-ray spectrometry showed values [Bqkg-1] in the range: 15-117 for 238U, 21-115 for 226Ra, 33-65 for 210Pb, 20-69 for 232Th, 324-736 for 40K, and 2-59 for 137Cs. Surface soil radio-activity that could have resulted from deposition of radionuclides from airborne discharges or resuspension of ash from disposal sites showed no enhanced levels. It was found that variation of soil textural properties, pH values, and carbonate content influenced activity levels of natural radionuclides while radiocesium activities were associated with soil organic matter content. Modification of some soil properties was observed in the immediate vicinity (<1 km of power plants where the soil was more alkaline with coarser particles (0.2-0.05 mm and carbonates accumulated. Calculated average values of the absorbed gamma dose rate and annual external effective dose originating from the terrestrial radionuclides were 69.4 nGy/h and 0.085 mSv, respectively. [Projekat Ministarstva nauke Republike Srbije, br. 4007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation

  2. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-01

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

  4. Gamma knife treatment of rat glioma Influences of irradiation dose on apoptosis and necrosis

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Mianshun Pan; Xinggen Fang

    2008-01-01

    BACKGROUND: Apoptosis and necrosis are cellular death mechanisms that are induced in glioma cells following gamma knife irradiation. Increased apoptosis is essential for maintaining and enhancing treatment efficacy.OBJECTIVE: To observe apoptotic and necrotic mechanisms of rat glioma models induced by gamma knife treatment and to analyze the influences of irradiation doses on apoptosis and necrosis. DESIGN: Controlled animal experiment. SETTING: Cancer Hospital of Tianjin Medical University and Gamma Knife Center of Hefei Brain Hospital.MATERIALS: Eighteen female specific pathogen free Sprague Dawley rats, weighing 180-210 g and 5-6 weeks old, were purchased from the Experimental Animal Center, Medical College of Suzhou University. Rat C6 glioma cells were purchased from the cell bank of Chinese Academy of Sciences. Annexin V-FITC Reagent Kit (Bender Med System. Company, USA) and a flow cytometer (Becton Dickinson FACSCalibur) were provided.METHODS: The experiment was conducted at the Cancer Hospital of Tianjin Medical University and Gamma Knife Center of Hefei Brain Hospital from December 2006 to May 2007. All rats were inoculated with C6 glioma cells, i.e., 4 μL of a C6 glioma cell suspension was injected 5 mm deep in the cortex. All rats were divided randomly into a model group, 9-Gy treatment group, and 12-Gy treatment group. There were six rats in each group.MAIN OUTCOME MEASURES: Apoptosis and necrosis of normal brain tissue and glioma were observed by Flow Cytometry one week after irradiation, and pathological changes to tumor tissue were identified by HE staining.RESULTS: Eighteen rats were initially selected for the study: two rats from the model and 12-Gy treatment groups died from accidental anesthesia. The remaining 16 rats were included in the final result analysis. Cellular apoptosis and necrosis: apoptosis and necrosis were significantly increased in the treatment groups after gamma knife irradiation, compared to the model group (P < 0

  5. Angular Gamma Dose Rate Distribution at the Surface of Injected Ducted Concrete Shield

    Science.gov (United States)

    Sayed Ahmed, Fikria M.; Abboud, Aida

    The shielding problems that arise due to the irregular penetrations such as neutral beam injection ducts should be treated carefully to aid in the shield design. The present work was undertaken to describe the effects arising due to radiation streaming through the neutral beam injector ducts (NBID) on the angular distribution of the total gamma ray doses at the outer surface of illmenite concrete shield ( = 4.6g/cm3). The shield is pierced with NBID of different diameters and lengths.The measurements were performed using a collimated beam of both gamma rays and neutrons emitted from one of the horizontal channels of the ET-RR-1 reactor. The measurements were carried out using 7LiF teflon thermoliminescent dosimeters. Generally the obtained data reveal that the presence of the total dose increase at the centerline of NBID and which in turn tends to decrease with the increase of scattered angle. An empirical formula describing the differential dose rate ratio is predicted. The experimental data obtained reveal good agreement with the calculated ones.Translated AbstractDie radiale Verteilung der -Dosisrate auf der Oberfläuche einer durchlöcherten BetonabschirmungAbschirmprobleme, die ihren Ursprung in irregulärem Durchlaßvermögen haben, sollten sorgfältig untersucht werden, um die Konstruktion von Abschirmungen zu unterstützen. In der vorliegenden Arbeit wird versucht, den Effekt von ausgetretener Strahlung (nach dem Mechanismus der neutralen Strahlinjektordurchführung NBID) auf die radiale Verteilung der totalen y- Strahlendosis auf der äußeren Oberfläche einer Illmenitbetonabschirmung ( = 4,6 g/cm3) aufzuzeigen. Der Schild ist mit NBID's verschiedener Längen und Durchmesser versehen. Die experimentellen Werte stimmen gut mit berechneten überein. Eine empirische Formel für die radiale Verteilung wird angegeben.

  6. SU-E-T-647: Quality Assurance of VMAT by Gamma Analysis Dependence On Low-Dose Threshold

    Energy Technology Data Exchange (ETDEWEB)

    Song, J; Kim, M; Lee, S; Lee, M; Suh, T [Department of Biomedical Engineering, Reasearch Institute of Biomedical Engineering, The Catholic University of Korea, Seoul (Korea, Republic of); Park, S [Department of Biomedical Engineering, Reasearch Institute of Biomedical Engineering, The Catholic University of Korea, Seoul (Korea, Republic of); Department of Radiation Oncology, Uijeongbu St. Mary’s Hospital, Gyeonggi-do (Korea, Republic of)

    2015-06-15

    Purpose: The AAPM TG-119 instructed institutions to use low-dose threshold (LDT) of 10% or a ROI determined by the jaw when they collected gamma analysis QA data of planar dose distribution. Also, based on a survey by Nelms and Simon, more than 70% of institutions use a LDT between 0% and 10% for gamma analysis. However, there are no clinical data to quantitatively demonstrate the impact of the LDT on the gamma index. Therefore, we performed a gamma analysis with LDTs of 0% to 15% according to both global and local normalization and different acceptance criteria: 3%/3 mm, 2%/2 mm, and 1%/1 mm. Methods: A total of 30 treatment plans—10 head and neck, 10 brain, and 10 prostate cancer cases—were randomly selected from the Varian Eclipse TPS, retrospectively. For the gamma analysis, a predicted portal image was acquired through a portal dose calculation algorithm in the Eclipse TPS, and a measured portal image was obtained using a Varian Clinac iX and an EPID. Then, the gamma analysis was performed using the Portal Dosimetry software. Results: For the global normalization, the gamma passing rate (%GP) decreased as the LDT increased, and all cases of low-dose thresholds exhibited a %GP above 95% for both the 3%/3 mm and 2%/2 mm criteria. However, for local normalization, the %GP increased as LDT increased. The gamma passing rate with LDT of 10% increased by 6.86%, 9.22% and 6.14% compared with the 0% in the case of the head and neck, brain and prostate for 3%/3 mm criteria, respectively. Conclusion: Applying the LDT in the global normalization does not have critical impact to judge patient-specific QA results. However, LDT for the local normalization should be carefully selected because applying the LDT could affect the average of the %GP to increase rapidly.

  7. Characterization of Neutron and Gamma Dose in the Irradiation Cell of Texas A and M University Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Latha; Reece, Warren D. [Nuclear Science Center, Texas A and M University, College Station, Texas (United States); Chirayath, Sunil S. [Nuclear Security Science and Policy Institute, Texas A and M University, College Station, Texas (United States); Aghara, Sukesh [Prairie View A and M University, Prairie View, Texas (United States)

    2011-07-01

    The Monte Carlo N-Particle (MCNP) code was used to develop a three dimensional computational model of the Texas A and M University Nuclear Science Center Reactor (NSCR) operating against the irradiation (dry cell) at steady state thermal power of 1 MW. The geometry of the NSCR core and the dry cell were modeled in detail. NSCR is used for a wide variety of experiments that utilizes the dry cell for neutron as well as gamma irradiation of samples. Information on the neutron and gamma radiation environment inside the dry cell is required to facilitate irradiation of samples. This paper presents the computed neutron flux, neutron and gamma dose rate, and foil reaction rates in the dry cell, obtained through MCNP5 simulations of the NSCR core. The neutron flux was measured using foil activation method and the reaction rates obtained from {sup 197}Au(n,{gamma}){sup 198}Au and {sup 54}Fe(n,p){sup 54}Mn were compared with the model and they showed agreement within {approx} 20%. The gamma dose rate at selected locations inside the dry cell was measured using radiochromic films and the results indicate slightly higher dose rates than predicted from the model. This is because the model calculated only prompt gamma dose rates during reactor operation while the radiochromic films measured gammas from activation products and fission product decayed gammas. The model was also used to calculate the neutron energy spectra for the energy range from 0.001 eV- 20 MeV. (authors)

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

    Science.gov (United States)

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

    2011-01-01

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

  9. Induction of a Radio-Adaptive Response by Low-dose Gamma Irradiation in Mouse Cardiomyocytes

    Science.gov (United States)

    Westby, Christian M.; Seawright, John W.; Wu, Honglu

    2011-01-01

    One of the most significant occupational hazards to an astronaut is the frequent exposure to radiation. Commonly associated with increased risk for cancer related morbidity and mortality, radiation is also known to increase the risk for cardiovascular related disorders including: pericarditis, hypertension, and heart failure. It is believed that these radiation-induced disorders are a result of abnormal tissue remodeling. It is unknown whether radiation exposure promotes remodeling through fibrotic changes alone or in combination with programmed cell death. Furthermore, it is not known whether it is possible to mitigate the hazardous effects of radiation exposure. As such, we assessed the expression and mechanisms of radiation-induced tissue remodeling and potential radio-adaptive responses of p53-mediated apoptosis and fibrosis pathways along with markers for oxidative stress and inflammation in mice myocardium. 7 week old, male, C57Bl/6 mice were exposed to 6Gy (H) or 5cGy followed 24hr later with 6Gy (LH) 137Cs gamma radiation. Mice were sacrificed and their hearts extirpated 4, 24, or 72hr after final irradiation. Real Time - Polymerase Chain Reaction was used to evaluate target genes. Apoptotic genes Bad and Bax, pro-cell survival genes Bcl2 and Bcl2l2, fibrosis gene Vegfa, and oxidative stress genes Sod2 and GPx4 showed a reduced fold regulation change (Bad,-6.18; Bax,-6.94; Bcl2,-5.09; Bcl2l2,-4.03; Vegfa, -11.84; Sod2,-5.97; GPx4*,-28.72; * = Bonferroni adjusted p-value p53-mediated apoptosis genes Casp3, Casp9, Trp53, and Myc exhibited down-regulation but did not achieve a notable level of significance 4hr after H. 24hr after H, genetic down-regulation was no longer present compared to 24hr control. These data suggest a general reduction in genetic expression 4hrs after a high dose of gamma radiation. However, pre-exposure to 5cGy gamma radiation appears to facilitate a radio-adaptive response that mitigates the reduction in genetic expression associated

  10. Study of the Effect of Iron Loaded with B4C on the Total Gamma Doses Emitted from Laminated Shield

    Science.gov (United States)

    Makarious, A. S.; Maayouf, R. M. A.; Megahid, R. M.; El-Sayed Abdo, A.

    In this work a comparative study of the effect of iron loaded with B4C on the suppression of gamma-rays in a laminated shield of water, iron and either ordinary or limenite concrete have been carried out. It was found that B4C loaded with iron has a remarkable effect on the suppression of gamma doses all through the laminated shield. The suppression is more pronounced in the concrete layer. It was also found that the decrease of gamma doses in ilmenite concrete is 1.7 that one for ordinary concrete.Translated AbstractUntersuchung des Einflusses von mit B4C angereichertem Eisen auf die Gesamt-Gamma-Dosis aus einem laminierten SchildDer Effekt von mit B4C angereichertem Eisen auf die Abschirmung von Gamma-Strahlen durch einen laminierten Schild aus Wasser, Eisen und entweder gewöhnlichem oder Ilmenitebeton wird vergleichend untersucht. Es erweist sich ein bemerkenswerter Effekt des angereicherten Eisens auf die Abschwächung der Gamma-Dosis im gesamten Schild. Sie ist in der Betonschicht am ausgeprägtesten. Die Abnahme der Gamma-Dosis in Ilmenitebeton ist etwa 1,7fach der in gewöhnlichem Beton.

  11. Evaluation of neutron dose and gamma dose at thermal facility of Peruvian research reactor RP-10; Evaluacion de la dosis gamma y de neutrones en la facilidad termica del reactor peruano de investigacion RP-10

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Javier; Miranda, Hector; Aparicio, Claudia; Lazaro, Gerardo [Instituto Peruano de Energia Nuclear (IPEN), Lima (Peru). Dept. de Calculo, Analisis y Seguridad (CASE)]. E-mail: hmcmiranda@hotmail.com; jjgb76@yahoo.com; caparicio@scientist.com; glazaro@ipen.gob.pe; Zuniga, Agustin [Instituto Peruano de Energia Nuclear (IPEN), Lima (Peru). Direccion General de Instalaciones (DGI)]. E-mail: azuniga@ipen.gob.pe

    2005-07-01

    One of main lines of work in the Peruvian nuclear reactor RP-10, is a complex systems simulation by mean of Monte Carlo technique, oriented in particular to characterization of irradiation facilities. In this work it is presented the comparison of experimental measurements, based in measure of thermal, epithermal and fast neutron flux distribution, neutron dose and gamma dose at thermal facility of RP-10, with the MCNP4B compute code, being observed a good agreement between both results. The neutron flux measures were carried out by irradiation of gold, indium and nickel metallic monitors; then it were measured the activities using a gamma spectrometry chain based on a hyperpure germanium (HPGe) detector. With these results the neutron dose was determined, and it was also measured, using a equipment based on a boron trifluoride detector (BF3, NRC-RemRad). A device based on Geiger Mueller detector (FAG-FH40FE) was used for the gamma dose rate measurement. Finally there were measured both gamma and neutron dose rate using TLD-600 and TLD-700 thermoluminescent dosimeters, which were previously characterized. (author)

  12. Dependence of malformation upon gestational age and exposed dose of gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung-Ho; Lee, Jong-Hwan; Oh, Heon; Kim, Se-Ra [Chonnam National Univ., Kwangju (Korea, Republic of). Coll. of Veterinary Medicine; Lee, Cha-Soo; Jo, Sung-Kee; Kim, Tae-Hwan; Lee, Yun-Sil

    2001-09-01

    In order to evaluate the importance of gestational age and the dose-incidence relationship by gamma radiation, pregnant ICR mice at gestational days from 2.5 to 15.5 days post-coitus (p.c.) were exposed to a single dose of 2.0 Gy and also at day 11.5 after conception, which was the most sensitive stage for the induction of major congenital malformations. The animals were sacrificed on day 18 of gestation and the fetuses were examined for mortality, growth retardation, changes in head size and other morphological abnormalities. The only demonstrable effect of irradiation during the pre-implantation period was an increase in prenatal mortality. Resorptions were maximal on exposure at day 2.5 after conception. The pre-implantation irradiated embryos which survived did not show any major fetal abnormalities. A small head, growth retardation, a cleft palate, dilatation of the cerebral ventricle, a renal pelvis, and abnormalities of the extremities and tail after exposure were prominent during the organogenesis period, especially on day 11.5 of gestation. As for the dose-incidence relationship, the incidence of a small head, growth-retarded fetuses, a cleft palate, dilatation of cerebral ventricle and abnormalities of the extremities in live fetuses rose as the radiation dose increased. The result indicated that the late period of organogenesis in the development of the brain, skull and extremities of a mouse was a particularly sensitive phase. The threshold doses of radiation that induced a cleft palate and dilatation of the cerebral ventricle, and abnormal extremities were between 1.0 and 2.0 Gy, and between 0.5 and 1.0 Gy, respectively. (author)

  13. An investigation of eye lens dose of stereotactic radiosurgery for trigeminal neuralgia using Leksell Gamma Knife model C.

    Science.gov (United States)

    Liang, Cheng-Loong; Ho, Meng-Wei; Lu, Kang; Tsai, Yu-Duan; Liliang, Po-Chou; Wang, Kuo-Wei; Chen, Han-Jung

    2006-12-01

    The authors conducted a study to assess the eye lens dosimetry in trigeminal neuralgia (TN) treatment when using the Leksell Gamma Knife model C. Phantom studies were used to measure the maximal dose reaching the eye lens with and without eye shielding. Six consecutive patients with TN were evaluated for Gamma Knife surgery (GKS). The maximum prescribed dose of 80 Gy was delivered with a single shot using the 4-mm collimator helmet. High-sensitivity thermoluminescence dosimeter chips (TLDCs) were used to measure the dosimetry. In vitro, the Leksell GammaPlan (LGP) system predicted the mean maximal doses of 1.08 +/- 0.08 and 0.15 +/- 0.01 Gy (mean +/- standard deviation) to the lens ipsilateral to the treated trigeminal nerve without and with eye shielding, respectively. The TLDCs-measured dosimetry indicated the mean maximal doses of 1.12 +/- 0.09 and 0.17 +/- 0.01 Gy without and with eye shielding, respectively. The maximal doses to the lens contralateral to the nerve were similar. In vivo, the LGP predicted the mean maximal doses to the lens ipsilateral to the treated nerve as 1.1 +/- 0.07 and 0.16 +/- 0.02 Gy, respectively, without and with eye shielding. The dosimetry measured by TLDCs indicated the mean maximal dose to the lens ipsilateral to the treated nerve as 0.17 +/- 0.02 Gy with eye shielding. The mean maximal doses to the lens contralateral to the nerve were similar. Using the 110 and 125 degrees gamma angles, the LGP predicted the mean maximal doses of 0.32 +/- 0.04 and 0.12 +/- 0.04 Gy to the lens without and with eye shielding, respectively. Patients with TN undergoing GKS without eye shielding may develop cataracts due to the high radiation dose to the eye lenses. The authors suggest the routine use of bilateral eye shielding for the patients.

  14. 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.

  15. A Performance Evaluation of a Notebook PC under a High Dose-Rate Gamma Ray Irradiation Test

    Directory of Open Access Journals (Sweden)

    Jai Wan Cho

    2014-01-01

    Full Text Available We describe the performance of a notebook PC under a high dose-rate gamma ray irradiation test. A notebook PC, which is small and light weight, is generally used as the control unit of a robot system and loaded onto the robot body. Using TEPCO’s CAMS (containment atmospheric monitoring system data, the gamma ray dose rate before and after a hydrogen explosion in reactor units 1–3 of the Fukushima nuclear power plant was more than 150 Gy/h. To use a notebook PC as the control unit of a robot system entering a reactor building to mitigate the severe accident situation of a nuclear power plant, the performance of the notebook PC under such intense gamma-irradiation fields should be evaluated. Under a similar dose-rate (150 Gy/h gamma ray environment, the performances of different notebook PCs were evaluated. In addition, a simple method for a performance evaluation of a notebook PC under a high dose-rate gamma ray irradiation test is proposed. Three notebook PCs were tested to verify the method proposed in this paper.

  16. Effects of low dose gamma radiation on the growth, enzyme and photosynthetic activities of gourd (lagenaria siceraria)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. S.; Beak, M. H.; Lee, H. Y.; Lee, Y. K. [KAERI, Taejon (Korea, Republic of)

    2001-10-01

    Gourd seeds were irradiated with the doses of 0 {approx} 20 Gy to investigate the effect of the low lose gamma radiation on the early growth and physiological activity. The stimulating effects of the low dose gamma radiation on the early growth were not noticeably high, but were increased generally 4 {approx} 16 Gy irradiation group. The catalase and peroxidase activity of cotylendon from seeds irradiated with gamma radiation were increased at 8 Gy irradiation group and peroxidase activity of leaf was noticeably high at 4 Gy irradiation group. The photochemical yield of PSII, estimated as Fv/Fm, was decreased with increasing illumination time by 50% after 4 hours while Fo did not change. Interestingly, Fv/Fm in plants of 4 Gy irradiation group was decreased less showing 40% of inhibition after 4 hr, indicating that the low dose gamma radiation increased resistance of plants to photoinhibition. Changes in the effective quantum yield of PSII(1-F/Fm'), {phi}{sub PSII} and I/Fo-1/Fm, a measure of the rate constant of excitation trapping by the PSII reaction center, showed similar pattern as Fv/Fm. These results showed the positive effect of low dose gamma radiation on the seedling growth or physiological activities gourd via increasing photoprotective capacities of photosynthetic apparatus.

  17. Evolving Adjustments to External (Gamma) Slope Factors for CERCLA Risk and Dose Assessments - 12290

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Stuart [U.S. Environmental Protection Agency (United States)

    2012-07-01

    To model the external exposure pathway in risk and dose assessments of radioactive contamination at Superfund sites, the U.S. Environmental Protection Agency (EPA) uses slope factors (SFs), also known as risk coefficients, and dose conversion factors (DCFs). Without any adjustment these external radiation exposure pathways effectively assumes that an individual is exposed to a source geometry that is effectively an infinite slab. The concept of an 'infinite slab' means that the thickness of the contaminated zone and its aerial extent are so large that it behaves as if it were infinite in its physical dimensions. EPA has been making increasingly complex adjustments to account for the extent of the contamination and its corresponding radiation field to provide more accurate risk and dose assessment modeling when using its calculators. In most instances, the more accurate modeling results derived from these gamma adjustments are less conservative. The notable exception are for some radionuclides in rooms with contaminated walls, ceiling, and floors, and the receptor is in location of the room with the highest amount of radiation exposure, usually the corner of small rooms and the center of large conference rooms. (authors)

  18. Effect of exposure to low-dose [gamma] radiation during late organogenesis in the mouse fetus

    Energy Technology Data Exchange (ETDEWEB)

    Devi, P.U.; Baskar, R.; Hande, M.P. (Kasturba Medical College, Manipal (India))

    1994-04-01

    The adominal region of pregnant Swiss mice was exposed to 0.05 to 0.50 of [gamma] radiation on day 11.5 postcoitus. The animals were sacrificed on day 18 gestation and the fetuses were examined for mortality, growth retardation, changes in head size and brain weight, and incidence of microphthalmia. No marked increase in fetal mortality or growth retardation was observed below 0.25 Gy; the increase in these parameters was significant only at 0.50 Gy. A significant reduction in head size and brain weight and a significant increase in the incidence of microphthalmia were observed at doses above 0.15 Gy. Detectable levels of microcephaly and microphthalmia were evident even at 0.10 Gy. A linear dose response was seen for these effects in the dose range of 0.05 to 0.15 Gy. It is concluded that the late period of organogenesis in the mouse, especially between days 10 and 12 postcoitus, is a particularly sensitive phase in the development of the skull, brain and eye. 21 refs., 4 figs., 4 tabs.

  19. High doses of gamma radiation suppress allergic effect induced by food lectin

    Science.gov (United States)

    Vaz, Antônio F. M.; Souza, Marthyna P.; Vieira, Leucio D.; Aguiar, Jaciana S.; Silva, Teresinha G.; Medeiros, Paloma L.; Melo, Ana M. M. A.; Silva-Lucca, Rosemeire A.; Santana, Lucimeire A.; Oliva, Maria L. V.; Perez, Katia R.; Cuccovia, Iolanda M.; Coelho, Luana C. B. B.; Correia, Maria T. S.

    2013-04-01

    One of the most promising areas for the development of functional foods lies in the development of effective methods to reduce or eliminate food allergenicity, but few reports have summarized information concerning the progress made with food irradiation. In this study, we investigated the relationship between allergenicity and molecular structure of a food allergen after gamma irradiation and evaluate the profile of the allergic response to irradiated allergens. Cramoll, a lectin isolated from a bean and used as a food allergen, was irradiated and the possible structural changes were accompanied by spectrofluorimetry, circular dichroism and microcalorimetry. Subsequently, sensitized animals subjected to intragastric administration of non-irradiated and irradiated Cramoll were treated for 7 days. Then, body weight, leukocytes, cytokine profiles and histological parameters were also determined. Cramoll showed complete inhibition of intrinsic activity after high radiation doses. Changes in fluorescence and CD spectra with a simultaneous collapse of the tertiary structure followed by a pronounced decrease of native secondary structure were observed after irradiation. After oral challenge, sensitized mice demonstrate an association between Cramoll intake, body weight loss, eosinophilia, lymphocytic infiltrate in the gut and Eotaxin secretion. Irradiation significantly reduces, according to the dose, the effects observed by non-irradiated food allergens. We confirm that high-dose radiation may render protein food allergens innocuous by irreversibly compromising their molecular structure.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Fujio; Kouno, Tomohiro; Ohno, Takeshi [Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto 862-0976 (Japan); Kakei, Kiyotaka; Yoshiyama, Fumiaki [Department of Radiotherapy, Kumamoto University Hospital, 1-1-1 Honjyo, Kumamoto 860-8556 (Japan); Kawamura, Shinji [Department of Radiotherapy, Miyazaki University Hospital, 5200 Kihara Ohaza Kiyotake-Machi, Miyazaki 889-1692 (Japan)

    2013-09-15

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

  2. Neutron-gamma flux and dose calculations in a Pressurized Water Reactor (PWR

    Directory of Open Access Journals (Sweden)

    Brovchenko Mariya

    2017-01-01

    Full Text Available The present work deals with Monte Carlo simulations, aiming to determine the neutron and gamma responses outside the vessel and in the basemat of a Pressurized Water Reactor (PWR. The model is based on the Tihange-I Belgian nuclear reactor. With a large set of information and measurements available, this reactor has the advantage to be easily modelled and allows validation based on the experimental measurements. Power distribution calculations were therefore performed with the MCNP code at IRSN and compared to the available in-core measurements. Results showed a good agreement between calculated and measured values over the whole core. In this paper, the methods and hypotheses used for the particle transport simulation from the fission distribution in the core to the detectors outside the vessel of the reactor are also summarized. The results of the simulations are presented including the neutron and gamma doses and flux energy spectra. MCNP6 computational results comparing JEFF3.1 and ENDF-B/VII.1 nuclear data evaluations and sensitivity of the results to some model parameters are presented.

  3. 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)

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

    Science.gov (United States)

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

    2010-12-01

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

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

    Science.gov (United States)

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

    2010-12-01

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

  6. Determination of scattered gamma radiation in the calibration of environmental dose rate meters

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Hedemann Jensen, P.

    1992-01-01

    Practical free-field and shadow-shield calibration techniques using a variety of environmental dose rate meters were studied, and experimental and theoretical determinations were made of the contribution of scattered photons to the air kerma rate from certificated Cs-137, Co-60 and Ra-226 gamma...... the detector responses. Insignificant differences of the order of 1 % between the results for the two geometries were found both experimentally and theoretically. It is thus concluded that the scattered radiation from surrounding buildings farther away than around 15 m from a calibration set-up contributes...... negligibly to the detector response relative to that from ground and air. Shadow-shield measurements were used to deduce the contribution to the response from the scattered radiation in free-field geometries and the experimentally obtained results were found to agree agree extremely well with those...

  7. Assessment of the radiological impact of gamma and radon dose rates at former U mining sites in Tajikistan.

    Science.gov (United States)

    Lespukh, E; Stegnar, P; Yunusov, M; Tilloboev, H; Zyazev, G; Kayukov, P; Hosseini, A; Strømman, G; Salbu, B

    2013-12-01

    An assessment of the radiological situation due to exposure to gamma radiation, radon ((222)Rn) and thoron ((220)Rn) was carried out at former uranium (U) mining and processing sites in Taboshar and at Digmai in Tajikistan. Gamma dose rate measurements were made using various field instruments. (222)Rn/(220)Rn measurements were carried out with field instruments for instantaneous measurements and then discriminative (222)Rn/(220)Rn solid state nuclear track detectors (SSNTD) were used for longer representative measurements. The detectors were exposed for an extended period of time in different outdoor and indoor public and residential environments at the selected U legacy sites. The results showed that gamma, (222)Rn and (220)Rn doses were in general low, which consequently implies a low to relatively low radiological risk. The radiation doses deriving from external radiation (gamma dose rate), indoor (222)Rn and (220)Rn with their short-lived progenies did not exceed national or international standards. At none of the sites investigated did the average individual annual effective doses exceed 10 mSv, the recommended threshold value for the general public. A radiation hazard could be associated with exceptional situations, such as elevated exposures to ionizing radiation at the Digmai tailings site and/or in industrial facilities, where gamma and (222)Rn/(220)Rn dose rates could reach values of several 10 mSv/a. Current doses of ionizing radiation do not represent a hazard to the health of the resident public, with the exception of some specific situations. These issues should be adequately addressed to further reduce needless exposure of the resident public to ionizing radiation.

  8. Low-Dose Gamma Irradiation of Decellularized Heart Valves Results in Tissue Injury in Vitro and in Vivo

    Science.gov (United States)

    Helder, Meghana R. K.; Hennessy, Ryan S.; Spoon, Daniel B.; Tefft, Brandon J.; Witt, Tyra A.; Marler, Ronald J.; Pislaru, Sorin V.; Simari, Robert D.; Stulak, John M.; Lerman, Amir

    2017-01-01

    Background Decellularized heart valves are emerging as a potential alternative to current bioprostheses for valve replacement. While techniques of decellularization have been thoroughly examined, terminal sterilization techniques have not received the same scrutiny. Methods This study evaluated low dose gamma irradiation as a sterilization method for decellularized heart valves. Incubation of valves and transmission electron microscopy evaluation after different doses of gamma irradiation were used to determine the optimal dose of gamma irradiation. Quantitative evaluation of mechanical properties was done by tensile mechanical testing of isolated cusps. Sterilize decellularized heart valves were tested in a sheep model (n=3, 1 1,500 Gy and 2 3,000 Gy) of pulmonary valve replacement. Results Valves sterilized with gamma radiation between 1,000 Gy and 3,000 Gy were found to be optimal with in-vitro testing. However, with in-vivo showed deteriorating valve function within 2 months. On explant the valve with 1,500 Gy gamma irradiation showed signs of endocarditis with neutrophils on hematoxylin and eosin staining, positive gram stain resembling streptococcus infection. The 3,000 Gy valves had no evidence of infection, but the hematoxylin and eosin staining showed evidence of wound remodeling with macrophages and fibroblasts. Tensile strength testing showed decreased strength (0 Gy-2.53±0.98 MPa, 1,500 Gy-2.03±1.23 MPa, 3,000 Gy-1.26±0.90 MPa) with increasing levels of irradiation. Conclusions Low dose gamma irradiation does not maintain the mechanical integrity of valves and the balance between sterilization and damage may not be able to be achieved with gamma irradiation. Other methods of terminal sterilization must be pursued and evaluated. PMID:26453425

  9. Evaluation of the Effects of Inhomogeneities on Dose Profiles Using Polymer Gel Dosimeter and Monte Carlo Simulation in Gamma Knife

    Directory of Open Access Journals (Sweden)

    Tayeb Allahverdi Pourfallah

    2012-03-01

    Full Text Available Introduction Polymer gel dosimeters offer a practical solution to 3D dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. In this study, EGSnrc calculated and PAGAT polymer gel dosimeter measured dose profiles from single shot irradiation with 18 mm collimator of Gamma Knife in homogeneous and inhomogeneous phantoms were compared with each other. Materials and Methods The head phantom was a custom-built 16 cm diameter plexiglas sphere. Inside the phantom, there were two cubic cutouts for inserting the gel vials and inhomogeneities. Following irradiation with the Gamma Knife unit, the polymer gel dosimeters were scanned with a 1.5 T MRI scanner. For the purpose of simulation the simplified channel of 60Co source of Gamma Knife BEAMnrc and for extracting the 3D dose distribution in the phantom, DOSXYZnrc codes were used. Results Within high isodose levels (>80%, there are dose differences higher than 7%, especially between air inserted and PTFE inserted phantoms, which were obtained using both simulation and experiment. This means that these values exceed the acceptance criterion of conformal radiotherapy and stereotactic radiosurgery (i.e., within some isodose levels, less than 93% of prescription dose are delivered to the target. Conclusion The discrepancies observed between the results obtained from heterogeneous and homogeneous phantoms suggest that Leksell Gamma Knife planning system (LGP predictions which assume the target as a homogeneous material must be corrected in order to take care of the air- and bone-tissue inhomogeneities.

  10. Effects of low dose gamma-ray radiation on the seed germination and physiological activity of vegetable crops

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. S.; Baek, M. H.; Lee, Y. G. [KAERI, Taejon (Korea, Republic of); Jung, K. H. [Kyunghee Univ., Yongin (Korea, Republic of)

    2000-10-01

    To determine the effect of low dose gamma-ray radiation on the germination rate and physiology of germinative seeds of Chinese cabbage(Brassica campestris L. cv. Hanyoreum) and radish(Raphanus sativus L. cv. Chungsukoungzoung). The germination rate of irradiation group was higher than that of the control. Especially it was highest at the early stage of induction. The germination rate of Chinese cabbage increased at 4 Gy-, 10 Gy- and 50 Gy irradiation group and that of radish increased at 2 Gy-, 6 Gy- and 10 Gy irradiation group. The seedling height of Chinese cabbage and radish increased positively in low dose irradiation group. The seedling height of Chinese cabbage was noticeably higher at 4 Gy and 10 Gy irradiation group and that of radish at 6 Gy irradiation group. The protein contents of seeds irradiated with low dose gamma-ray radiation was increased compared to that of the control especially at the early stage of induction. The enzyme activity of seeds irradiated with low dose of gamma-ray radiation was increased at 4 Gy and 10 Gy irradiation group. These results suggest that the germination and physiological activity of old seeds could be stimulated promisingly by the low dose gamma-ray radiation.

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

    Science.gov (United States)

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

    2016-02-21

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

  12. Radiometric modeling through the combined use of the EDR gamma scanner and the VISIPLAN dose assessment tool

    Energy Technology Data Exchange (ETDEWEB)

    Perez, J.M. [Laboratoria General de Electronica y Automatica, CIEMAT, Edificio 22, Avenida Complutense 22, E-28040 Madrid (Spain)]. E-mail: jm.perez@ciemat.es; Vermeersch, F. [SCK-CEN, Boeretang 200, 2400 Mol (Belgium); Vela, O. [Laboratoria General de Electronica y Automatica, CIEMAT, Edificio 22, Avenida Complutense 22, E-28040 Madrid (Spain); Burgos, E. de [Laboratoria General de Electronica y Automatica, CIEMAT, Edificio 22, Avenida Complutense 22, E-28040 Madrid (Spain)

    2004-11-11

    In this paper, we present the work performed on the integration of a new gamma scanner prototype, known as EDR, with a 3D-dose assessment software tool called VISIPLAN. It is one of the first approaches to merge gamma imaging instrumentation and a 3D-dose assessment program into a combined operative hardware-software solution for the characterization of a site in the field of radiation protection. The main features of the scanner design are presented here, together with a representative part of the tests performed during its characterization. The EDR directional sensitivity is determined for two gamma radiation fields originating from {sup 137}Cs and {sup 60}Co sources and forms the basis for the interpretation of the gamma scans using VISIPLAN. The combination of a 3D-source model and the detailed instrument response function can determine the source activities from the gamma scans, and also enables in a second step, the simulation of the dose-rate field on the site. The integration of the two tools was tested in a laboratory and validated in an industrial facility.

  13. Gamma ray radiation induced visible light absorption in P-doped silica fibers at low dose levels

    CERN Document Server

    Lu Ping; Kulkarni, N S; Brown, K

    1999-01-01

    A CCD Fiber Optic Spectrometer has been used to monitor the gamma ray radiation induced loss in P-doped fibers at different dopant concentrations (1, 5 and 10 mol%) with a light source (an incandescent bulb with a temperature of 2800-3000 K). The range of dose rates is limited to that used in medical applications (cancer treatments), that is 0.1 to 1.0 Gray per minute (Gy/min). At low integral dose level (<2.0 Gy) four absorption peaks were observed (470, 502, 540 and 600 nm) within the visible region. It has been observed that the radiation induced loss at 470 and 600 nm depends strongly on dose rate. At dose rates of 0.2 and 0.5 Gy/min the induced loss shows nonlinear relation to the total dose. However, at high dose rate (1.0 Gy/min) and low dose rate (0.1 Gy/min) it seems to have a linear dependence with total dose. The conversion from NBOHCs to GeX centers was observed during gamma radiation at low dose rates (0.1-0.5 Gy/min). At the wavelength of 502 and 540 nm, the radiation induced losses show exce...

  14. 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.

  15. Absorbed dose in AgBr in direct film for photon energies ( < 150 keV): relation to optical density. Theoretical calculation and experimental evaluation.

    Science.gov (United States)

    Helmrot, E; Alm Carlsson, G

    1996-01-01

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

  16. Regeneration of Murine Hair Follicles is Inhibited by Low-Dose-Rate Gamma Irradiation.

    Science.gov (United States)

    Sugaya, Kimihiko; Hirobe, Tomohisa; Ishihara, Yoshie; Inoue, Sonoe

    2016-10-01

    To determine whether the effects of low-dose-rate gamma (γ) irradiation are identifiable in the regeneration of murine hair follicles, we irradiated whole bodies of C57BL/10JHir mice in the first telogen phase of the hair cycle with (137)Cs γ-rays. The mice were examined for effects on hair follicles, including number, morphology, and pigmentation in the second anagen phase. Effects of γ-radiation on melanocyte stem cells were also investigated by the indirect immunolabeling of tyrosinase-related protein 2 (TRP2). Irradiated skin showed a decrease in hair follicle density and the induction of curved hair follicles along with the presence of white hairs and hypopigmented hair bulbs. There was a small, but not significant, change in the number of TRP2-positive melanocyte stem cells in the hair bulge region of the irradiated skin. These results suggest that low-dose rate γ-irradiation does not deplete melanocyte stem cells, but can damage stem cells and progenitors for both keratinocytes and melanocytes, thereby affecting the structure and pigmentation of regenerated hair follicles in the 2(nd) anagen phase.

  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.

  18. Gamma knife radiosurgery for vestibular schwannomas: results of hearing preservation in relation to the cochlear radiation dose.

    NARCIS (Netherlands)

    Timmer, F.C.A.; Hanssens, P.E.; Haren, A.E. van; Mulder, J.J.S.; Cremers, C.W.R.J.; Beynon, A.J.; Overbeeke, J.J. van; Graamans, K.

    2009-01-01

    OBJECTIVES/HYPOTHESIS: This study was designed to evaluate hearing preservation after gamma knife radiosurgery (GKRS) and to determine the relation between hearing preservation and cochlear radiation dose in patients with a sporadic vestibular schwannoma (VS). METHODS: Prospective study involving pa

  19. Effects of low doses of gamma irradiation on pine nuts (Araucaria angustifolia)

    Energy Technology Data Exchange (ETDEWEB)

    Modolo, Debora M.; Silva, Lucia A.C.S.; Arthur, Valter, E-mail: dmmodolo@cena.usp.br, E-mail: lcasilva@cena.usp.br, E-mail: arthur@cena.usp.br [Laboratorio de Radiobiologia e Ambiente, Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil); Harder, Marcia N.C.; Arthur, Paula B.; Arthur, Valter [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The Araucaria angustifolia, is known as the Pinheiro-do-Parana, Brazilian pine, Pine, Pine Tree Monkey, emerges as the main representative of the Rain Forest, also known as Araucaria Forest, part of the Atlantic Forest biome (Decree Law 750/1993). A major problem in implementing this plan is to stand the loss of germination of seeds. The storage conditions of the seeds of species, some time have been the subject of studies by various researchers. Several studies have shown that ionizing radiation can increase the germination rate, to break dormancy and plant production, thus appearing as an alternative method to increase the production of economically important crops. Despite the Hormesis Theory have been confirmed in experiments and observations made over the years, relatively few researchers who are dedicated to the study of this phenomenon. Due to losses of germination of pine nut, the aim of this work was to study the effect of low doses of gamma radiation on pine nut. The seeds were bought locally in the city of Piracicaba and irradiated with 0 (control), 0.25, 0.50, 0.75, 10, 12, 5, 15.0 and 17.5 Gy. Subsequently the seeds were planted in a plastic cup containing vermiculite as substrate. Evaluations of the germinated seeds number and measure the size of the plants every 10 days. The results indicated that the dose of 0.25 Gy there was a greater number of plants germinated and irradiation stimulated the growth of these plants. Already a lethal dose of the seeds was 15 Gy. (author)

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

    Science.gov (United States)

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

    2017-01-01

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

  1. 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

  2. Terrestrial gamma radiation dose study to determine the baseline for environmental radiological health practices in Melaka state, Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Ramli, Ahmad Termizi; Sahrone, Sallehudin; Wagiran, Husin [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johore Bahru, Johore, Malaysia (Malaysia)

    2005-12-15

    Environmental terrestrial gamma radiation dose rates were measured throughout Melaka, Malaysia, over a period of two years, with the objective of establishing baseline data on the background radiation level. Results obtained are shown in tabular, graphic and cartographic form. The values of terrestrial gamma radiation dose rate vary significantly over different soil types and for different underlying geological characteristics present in the study area. The values ranged from 54 {+-} 5 to 378 {+-} 38 nGy h{sup -1}. The highest terrestrial gamma dose rates were measured over soil types of granitic origin and in areas with underlying geological characteristics of an acid intrusive (undifferentiated) type. An isodose map of terrestrial gamma dose rate in Melaka was drawn by using the GIS application 'Arc View'. This was based on data collected using a NaI(Tl) scintillation detector survey meter. The measurements were taken at 542 locations. Three small 'hot spots' were found where the dose rates were more than 350 nGy h{sup -1}. The mean dose rates in the main population areas in the mukims (parishes) of Bukit Katil, Sungai Udang, Batu Berendam, Bukit Baru and Bandar Melaka were 154 {+-} 15, 161 {+-} 16, 160 {+-} 16, 175 {+-} 18 and 176 {+-} 18 nGy h{sup -1}, respectively. The population-weighted mean dose rate throughout Melaka state is 172 {+-} 17 nGy h{sup -1}. This is lower than the geographical mean dose rate of 183 {+-} 54 nGy h{sup -1}. The lower value arises from the fact that most of the population lives in the central area of the state where the lithology is dominated by sedimentary rocks consisting of shale, mudstone, phyllite, slate, hornfels, sandstone and schist of Devonian origin which have lower associated dose rates. The mean annual effective dose to the population from outdoor terrestrial gamma radiation was estimated to be 0.21 mSv. This value is higher than the world average of 0.07 mSv.

  3. SU-F-I-53: Coded Aperture Coherent Scatter Spectral Imaging of the Breast: A Monte Carlo Evaluation of Absorbed Dose

    Energy Technology Data Exchange (ETDEWEB)

    Morris, R [Durham, NC (United States); Lakshmanan, M; Fong, G; Kapadia, A [Carl E Ravin Advanced Imaging Laboratories, Durham, NC (United States); Greenberg, J [Duke University, Durham, NC (United States)

    2016-06-15

    Purpose: Coherent scatter based imaging has shown improved contrast and molecular specificity over conventional digital mammography however the biological risks have not been quantified due to a lack of accurate information on absorbed dose. This study intends to characterize the dose distribution and average glandular dose from coded aperture coherent scatter spectral imaging of the breast. The dose deposited in the breast from this new diagnostic imaging modality has not yet been quantitatively evaluated. Here, various digitized anthropomorphic phantoms are tested in a Monte Carlo simulation to evaluate the absorbed dose distribution and average glandular dose using clinically feasible scan protocols. Methods: Geant4 Monte Carlo radiation transport simulation software is used to replicate the coded aperture coherent scatter spectral imaging system. Energy sensitive, photon counting detectors are used to characterize the x-ray beam spectra for various imaging protocols. This input spectra is cross-validated with the results from XSPECT, a commercially available application that yields x-ray tube specific spectra for the operating parameters employed. XSPECT is also used to determine the appropriate number of photons emitted per mAs of tube current at a given kVp tube potential. With the implementation of the XCAT digital anthropomorphic breast phantom library, a variety of breast sizes with differing anatomical structure are evaluated. Simulations were performed with and without compression of the breast for dose comparison. Results: Through the Monte Carlo evaluation of a diverse population of breast types imaged under real-world scan conditions, a clinically relevant average glandular dose for this new imaging modality is extrapolated. Conclusion: With access to the physical coherent scatter imaging system used in the simulation, the results of this Monte Carlo study may be used to directly influence the future development of the modality to keep breast dose to

  4. Construction of a cytogenetic dose-response curve for low-dose range gamma-irradiation in human peripheral blood lymphocytes using three-color FISH.

    Science.gov (United States)

    Suto, Yumiko; Akiyama, Miho; Noda, Takashi; Hirai, Momoki

    2015-12-01

    In order to estimate biological doses after low-dose ionizing radiation exposure, fluorescence in situ hybridization (FISH) using three differentially colored chromosome painting probes was employed to detect exchange-type chromosome aberrations. A reference dose response curve was constructed using blood samples from a female donor whose lymphocytes consistently exhibited a low frequency of cells at the second mitosis under routine culture conditions. Aberration yields were studied for a total of about 155 thousand metaphases obtained from seven dose-points of gamma irradiations (0, 50, 100, 150, 200, 250 and 300mGy). In situ hybridization was performed using commercially available painting probes for chromosomes 1, 2 and 4. With the aid of an automated image-capturing method, exchange-type aberrations involving painted chromosomes were detected with considerable accuracy and speed. The results on the exchange-type aberrations (dicentrics plus translocations) at the seven dose-points showed a good fit to the linear-quadratic model (y=0.0023+0.0015x+0.0819x(2), P=0.83). A blind test proved the reproducibility of the reference dose-response relationship. In the control experiments using blood samples from another donor, the estimated doses calculated on the basis of the present reference curve were proved to be in good agreement with the actual physical doses applied. The present dose-response curve may serve as a means to assess the individual differences in cytogenetical radio-sensitivities.

  5. Inverse modelling of radionuclide release rates using gamma dose rate observations

    Science.gov (United States)

    Hamburger, Thomas; Evangeliou, Nikolaos; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2015-04-01

    Severe accidents in nuclear power plants such as the historical accident in Chernobyl 1986 or the more recent disaster in the Fukushima Dai-ichi nuclear power plant in 2011 have drastic impacts on the population and environment. Observations and dispersion modelling of the released radionuclides help to assess the regional impact of such nuclear accidents. Modelling the increase of regional radionuclide activity concentrations, which results from nuclear accidents, underlies a multiplicity of uncertainties. One of the most significant uncertainties is the estimation of the source term. That is, the time dependent quantification of the released spectrum of radionuclides during the course of the nuclear accident. The quantification of the source term may either remain uncertain (e.g. Chernobyl, Devell et al., 1995) or rely on estimates given by the operators of the nuclear power plant. Precise measurements are mostly missing due to practical limitations during the accident. The release rates of radionuclides at the accident site can be estimated using inverse modelling (Davoine and Bocquet, 2007). The accuracy of the method depends amongst others on the availability, reliability and the resolution in time and space of the used observations. Radionuclide activity concentrations are observed on a relatively sparse grid and the temporal resolution of available data may be low within the order of hours or a day. Gamma dose rates, on the other hand, are observed routinely on a much denser grid and higher temporal resolution and provide therefore a wider basis for inverse modelling (Saunier et al., 2013). We present a new inversion approach, which combines an atmospheric dispersion model and observations of radionuclide activity concentrations and gamma dose rates to obtain the source term of radionuclides. We use the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998; Stohl et al., 2005) to model the atmospheric transport of the released radionuclides. The

  6. Increased repair of {gamma}-induced DNA double-strand breaks at lower dose-rate in CHO cells

    Energy Technology Data Exchange (ETDEWEB)

    Boucher, D.; Hindo, J.; Averbeck, D. [Centre Universitaire d' Orsay, Inst. Curie-Section de Recherche, Orsay CEDEX (France)]. E-mail: dietrich.averbeck@curie.u-psud.fr

    2004-02-01

    DNA double-strand breaks (DSBs) are highly cell damaging. We asked whether for a given dose a longer irradiation time would be advantageous for the repair of DSBs. Varying the {gamma}-irradiation dose and its delivery time (0.05 Gy/min low dose-rate (LDR) compared with 3.5 Gy/min high dose-rate), confluent Chinese hamster ovary cells (CHO-K1) and Ku80 mutant cells (xrs-6) deficient in nonhomologous end-joining (NHEJ) were irradiated in agarose plugs at room temperature using a cesium-137 {gamma}-ray source. We used pulsed-field gel electrophoresis (PFGE) to measure DSBs in terms of the fraction of activity released (FAR). At LDR, one third of DSBs were repaired in CHO-K1 but not in xrs-6 cells, indicating the involvement of NHEJ in the repair of {gamma}-induced DSBs at a prolonged irradiation incubation time. To improve DSB measurements, we introduced in our PFGE protocol an antioxidant at the cell lysis step, thus avoiding free-radical side reactions on DNA and spurious DSBs. Addition of the metal chelator deferoxamine (DFO) decreased more efficiently the basal DSB level than did reduced glutathione (GSH), showing that measuring DSBs in the absence of DFO reduces precision and underestimates the role of NHEJ in the dose-rate effect on DSB yield. (author)

  7. Investigation of dose distribution in mixed neutron-gamma field of boron neutron capture therapy using N isopropylacrylamide gel

    Energy Technology Data Exchange (ETDEWEB)

    Bavarmegin, Elham; Sadremomtaz, Alireza [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Khalafi, Hossein; Kasesaz, Yaser [Dept. of Physics, University of Guilan, Rasht (Iran, Islamic Republic of); Khajeali, Azim [Medical Education Research Center, Tabriz (Iran, Islamic Republic of)

    2017-02-15

    Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the R2 maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

  8. Investigation of Dose Distribution in Mixed Neutron-Gamma Field of Boron Neutron Capture Therapy using N-Isopropylacrylamide Gel

    Directory of Open Access Journals (Sweden)

    Elham Bavarnegin

    2017-02-01

    Full Text Available Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT. In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the R2 maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

  9. Application of egs4 computer code for determination of gamma ray spectrum and dose rate distribution in gammacell 220

    Science.gov (United States)

    Raisali, G. R.; Sohrabpour, M.

    1993-10-01

    The EGS4 a Monte Carlo electron-photon transport simulation package together with a locally developed computer program "GCELL" has been used to simulate the transport of the gamma rays in Gammacell 220. An additional lead attenuator has been inserted in the chamber, has been included for those cases where lower dose rates were required. For three cases of 0, 1.35 and 4.0 cm thickness of added lead attenuators, the gamma spectrum, and dose rate distribution inside the chamber have been determined. For the case of no attenuator present, the main shield around the source cage has been included in the simulation program and its albedo effects have been investigated. The calculated dose rate distribution in the Gammacell chamber has been compared against measurements carried out with Fricke, PMMA and Gafchromic film dosimeters.

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

    DEFF Research Database (Denmark)

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

    1979-01-01

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

  11. Dose calculation in biological samples in a mixed neutron-gamma field at the TRIGA reactor of the University of Mainz.

    Science.gov (United States)

    Schmitz, Tobias; Blaickner, Matthias; Schütz, Christian; Wiehl, Norbert; Kratz, Jens V; Bassler, Niels; Holzscheiter, Michael H; Palmans, Hugo; Sharpe, Peter; Otto, Gerd; Hampel, Gabriele

    2010-10-01

    To establish Boron Neutron Capture Therapy (BNCT) for non-resectable liver metastases and for in vitro experiments at the TRIGA Mark II reactor at the University of Mainz, Germany, it is necessary to have a reliable dose monitoring system. The in vitro experiments are used to determine the relative biological effectiveness (RBE) of liver and cancer cells in our mixed neutron and gamma field. We work with alanine detectors in combination with Monte Carlo simulations, where we can measure and characterize the dose. To verify our calculations we perform neutron flux measurements using gold foil activation and pin-diodes. Material and methods. When L-α-alanine is irradiated with ionizing radiation, it forms a stable radical which can be detected by electron spin resonance (ESR) spectroscopy. The value of the ESR signal correlates to the amount of absorbed dose. The dose for each pellet is calculated using FLUKA, a multipurpose Monte Carlo transport code. The pin-diode is augmented by a lithium fluoride foil. This foil converts the neutrons into alpha and tritium particles which are products of the (7)Li(n,α)(3)H-reaction. These particles are detected by the diode and their amount correlates to the neutron fluence directly. Results and discussion. Gold foil activation and the pin-diode are reliable fluence measurement systems for the TRIGA reactor, Mainz. Alanine dosimetry of the photon field and charged particle field from secondary reactions can in principle be carried out in combination with MC-calculations for mixed radiation fields and the Hansen & Olsen alanine detector response model. With the acquired data about the background dose and charged particle spectrum, and with the acquired information of the neutron flux, we are capable of calculating the dose to the tissue. Conclusion. Monte Carlo simulation of the mixed neutron and gamma field of the TRIGA Mainz is possible in order to characterize the neutron behavior in the thermal column. Currently we also

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

    Science.gov (United States)

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

    2005-01-01

    A comparison of the standards for absorbed dose to water of the Bureau National de Métrologie - Laboratoire National Henri Becquerel (BNM-LNHB), Saclay, France and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co radiation under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result expressed as a ratio of the BNM-LNHB and the BIPM standards for absorbed dose to water is 0.9970 (0.0053). The degrees of equivalence between the BNM-LNHB and the other participants in this comparison have been calculated and the results are given in the form of a matrix for the 12 national metrology institutes (NMIs) that have taken part in the ongoing comparison for absorbed dose to water. A graphical presentation is also given. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by Section I of the Consultative Committee for Ionizing Radiation (CCRI(I)), according to the provisions of the Mutual Recognition Arrangement (MRA).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

  14. Dosimetric and Clinical Analysis of Spatial Distribution of the Radiation Dose in Gamma Knife Radiosurgery for Vestibular Schwannoma

    Energy Technology Data Exchange (ETDEWEB)

    Massager, Nicolas, E-mail: nmassage@ulb.ac.be [Gamma Knife Center, Hospital Erasme, Brussels (Belgium); Neurosurgery-Department, Hospital Erasme, Brussels (Belgium); Lonneville, Sarah [Gamma Knife Center, Hospital Erasme, Brussels (Belgium); Neurosurgery-Department, Hospital Erasme, Brussels (Belgium); Delbrouck, Carine [Gamma Knife Center, Hospital Erasme, Brussels (Belgium); ENT-Department, Hospital Erasme, Brussels (Belgium); Benmebarek, Nadir [Gamma Knife Center, Hospital Erasme, Brussels (Belgium); Neurosurgery-Department, Hospital Erasme, Brussels (Belgium); Desmedt, Francoise [Gamma Knife Center, Hospital Erasme, Brussels (Belgium); Radiophysics, Bordet Institute, Brussels (Belgium); Devriendt, Daniel [Gamma Knife Center, Hospital Erasme, Brussels (Belgium); Radiotherapy, Bordet Institute, Brussels (Belgium)

    2011-11-15

    Objectives: We investigated variations in the distribution of radiation dose inside (dose inhomogeneity) and outside (dose falloff) the target volume during Gamma Knife (GK) irradiation of vestibular schwannoma (VS). We analyzed the relationship between some parameters of dose distribution and the clinical and radiological outcome of patients. Methods and Materials: Data from dose plans of 203 patients treated for a vestibular schwannoma by GK C using same prescription dose (12 Gy at the 50% isodose) were collected. Four different dosimetric indexes were defined and calculated retrospectively in all plannings on the basis of dose-volume histograms: Paddick conformity index (PI), gradient index (GI), homogeneity index (HI), and unit isocenter (UI). The different measures related to distribution of the radiation dose were compared with hearing and tumor outcome of 203 patients with clinical and radiological follow-up of minimum 2 years. Results: Mean, median, SD, and ranges of the four indexes of dose distribution analyzed were calculated; large variations were found between dose plans. We found a high correlation between the target volume and PI, GI, and UI. No significant association was found between the indexes of dose distribution calculated in this study and tumor control, tumor volume shrinkage, hearing worsening, loss of functional hearing, or complete hearing loss at last follow-up. Conclusions: Parameters of distribution of the radiation dose during GK radiosurgery for VS can be highly variable between dose plans. The tumor and hearing outcome of patients treated is not significantly related to these global indexes of dose distribution inside and around target volume. In GK radiosurgery for VS, the outcome seems more to be influenced by local radiation dose delivered to specific structures or volumes than by global dose gradients.

  15. Production of sake from rice material exposed to {gamma}-radiation and technical development for its production. Characterization of low-dose exposed rice and small-scale brewing with it

    Energy Technology Data Exchange (ETDEWEB)

    Samuta, Takashi; Aramaki, Isao; Hashizume, Katsumi [National Research Institute of Brewing, Higashihiroshima, Hiroshima (Japan)

    1997-02-01

    The effects of {gamma}-ray radiation have been studied on rice materials for sake production. Previous studies showed that the radiation caused to decrease the viscosity as well as the gelatinization heat of those rice and also decrease the chain length of amylose in its endosperm starch. Therefore, it is possible that a new kind sake with excellent quality might be produced by exposing raw material to radiation at an appropriate dose. Here, it was demonstrated that even a low-dose radiation with {gamma}-ray may change various properties of rice including milling characteristics, water absorbing capacity, digestibility, viscosity etc. However, the characteristics as to fermentation were not affected so much and significant changes were observed only in the degree of coloring of the products. The effects of radiation on the constituents of sake were found to be comparatively small. For the production of matured sake, {gamma}-ray radiation was evaluated to be much effective, because the period of maturation was significantly shortened by using irradiated rice material. Thus, a fragrant matured-like sake could be easily produced from {gamma}-ray radiated rice. There remains a trouble in the coloring of the product. (M.N.)

  16. [Mechanism of injury of air-dry pea seeds under the influence of low doses of gamma-radiation].

    Science.gov (United States)

    Veselova, T V; Veselovskiĭ, V A

    2012-01-01

    The aim of this work was to determine which processes in air-dry seeds result in bimodal changes of the pea seed quality under the influence of low doses of gamma-radiation. Pea seeds (cv. "Nemchinovsky-85", harvest 2006, 82% germination persentage) were exposed to gamma-radiation at doses of 3, 10 and 100 Gy The germination percentage decreased to 45% four days after irradiation at the dose of 3 Gy, rised up to 87% at doses of 10 Gy, while the dose of 100 Gy killed the most part of seeds. Seed fractions differing in quality were selected using the metod of Room temperature phosphorecsence (RTP): strong seed frasction I from non-irradiated seeds; weak seed fraction II from the seeds irradiated at a dose of 3 Gy; dead seeds from the seeds irradiated at a dose of 100 Gy. ThermoChemiLuminecnsece (TCL) of seed powders and cotyledons was used. It was shown that the increase of the TCL level in the temperature range from 50 to 110 degreesC was associated with the lipid peroxidation products. The TCL level of seeds subjected to gamma-irradiation at a dose of 3 Gy was similar to that of non-irradiated seeds in the temperature range 50 to 100 degreesC. Therefore, lipid peroxidation was not the cause of the abnormal seedling appearance. The TCL level within this temperature range was increased only in seeds subjected to y-irradiation at a dose of 100 Gy. The TCL level at 150 degreesC was in proportion with the exogenous glucose amount. The increased TCL level of seeds subjected to y-irradiation at a dose of 3 Gy at 150 degreesC resulted from the increase of the glucose content. This means that the transition from the fraction of strong seeds into the fraction of weak ones was the result of the activation of hydrolysis processes. Decrease in the water content of seeds testified to utilization of bound water in this process. The decrease of the glucose content in the "improved" seeds subjected to gamma-irradiation at a dose of 10 Gy most probably indicates the participation of

  17. Evaluation of the occupational dose reduction after automation process for calibration of gamma radiation monitors; Avaliacao da reducao da dose ocupacional apos automacao do processo de calibracao de monitores de radiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Silva Junior, Iremar Alves da; Potiens, Maria da P.A., E-mail: iremarjr@gmail.com, E-mail: mppalbu@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    2013-11-01

    In this study, it was evaluated the occupational dose of calibration technicians responsible for monitor calibration of gamma radiation in the Instrument Calibration Laboratory of the Institute of Energy and Nuclear Research (IPEN-LCI), Sp, Brazil in your calibration activities before and after the automation of the process monitor calibration gamma be completed. Various measures of occupational dose values were taken inside the room calibration and the control room of radiators allowing calculate and show the occupational dose values in these environments during a full calibration of a monitor gamma radiation, showing the advantage of automation process, with decrease in dose and time calibration. (author)

  18. 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)

  19. Dose Determination using alanine detectors in a Mixed Neutron and Gamma Field for Boron Neutron Capture Therapy of Liver Malignancies

    DEFF Research Database (Denmark)

    Schmitz, T.; Blaickner, M.; Ziegner, M.

    2011-01-01

    be suitable for measurements in mixed neutron and gamma fields. Materials and Methods Two experiments have been carried out in the thermal column of the TRIGA Mark II reactor at the University of Mainz. Alanine dosimeters have been irradiated in a phantom and in liver tissue. Results For the interpretation......, in combination with flux measurements and Monte Carlo calculations with FLUKA, suggest that it is possible to establish a system for monitoring the dose in a mixed neutron and gamma field for BNCT and other applications in radiotherapy....

  20. 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.

  1. 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)

  2. On-Line High Dose-Rate Gamma Ray Irradiation Test of the CCD/CMOS Cameras

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Wan; Jeong, Kyung Min [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    In this paper, test results of gamma ray irradiation to CCD/CMOS cameras are described. From the CAMS (containment atmospheric monitoring system) data of Fukushima Dai-ichi nuclear power plant station, we found out that the gamma ray dose-rate when the hydrogen explosion occurred in nuclear reactors 1{approx}3 is about 160 Gy/h. If assumed that the emergency response robot for the management of severe accident of the nuclear power plant has been sent into the reactor area to grasp the inside situation of reactor building and to take precautionary measures against releasing radioactive materials, the CCD/CMOS cameras, which are loaded with the robot, serve as eye of the emergency response robot. In the case of the Japanese Quince robot system, which was sent to carry out investigating the unit 2 reactor building refueling floor situation, 7 CCD/CMOS cameras are used. 2 CCD cameras of Quince robot are used for the forward and backward monitoring of the surroundings during navigation. And 2 CCD (or CMOS) cameras are used for monitoring the status of front-end and back-end motion mechanics such as flippers and crawlers. A CCD camera with wide field of view optics is used for monitoring the status of the communication (VDSL) cable reel. And another 2 CCD cameras are assigned for reading the indication value of the radiation dosimeter and the instrument. In the preceding assumptions, a major problem which arises when dealing with CCD/CMOS cameras in the severe accident situations of the nuclear power plant is the presence of high dose-rate gamma irradiation fields. In the case of the DBA (design basis accident) situations of the nuclear power plant, in order to use a CCD/CMOS camera as an ad-hoc monitoring unit in the vicinity of high radioactivity structures and components of the nuclear reactor area, a robust survivability of this camera in such intense gamma-radiation fields therefore should be verified. The CCD/CMOS cameras of various types were gamma irradiated at a

  3. The depth-dependence of the biological effectiveness of 60Co gamma rays in a large absorber determined by dicentric chromosomes in human lymphocytes.

    Science.gov (United States)

    Schmid, Ernst; Roos, Hartmut; Kramer, Hans-Michael

    2008-01-01

    Radiobiological evidence is shown concerning a significant depth-dependence of the maximum relative biological effectiveness at limiting low doses (RBE(M)) of (60)Co gamma rays in a cubic polymethylmethacrylate (PMMA) phantom of 30 cm edge length. Using the dose-response curve for the dicentric data in human lymphocytes obtained in the present experiment at a depth of 20 cm, together with the comprehensive and consistent data set determined earlier at smaller depths of the PMMA phantom, there is an increase in the RBE(M) value by a factor of 2.18 +/- 1.25 at a depth of 20 cm relative to 1 cm in the phantom. All the dicentric data are based on identical exposure durations and irradiation temperatures as well as identical culture and evaluation conditions, with blood from the same donor.

  4. Emission rate estimation through data assimilation of gamma dose measurements in a Lagrangian atmospheric dispersion model.

    Science.gov (United States)

    Tsiouri, V; Kovalets, I; Andronopoulos, S; Bartzis, J G

    2012-01-01

    This paper presents an efficient algorithm for estimating the unknown emission rate of radionuclides in the atmosphere following a nuclear accident. The algorithm is based on assimilation of gamma dose rate measured data in a Lagrangian atmospheric dispersion model. Such models are used in the framework of nuclear emergency response systems (ERSs). It is shown that the algorithm is applicable in both deterministic and stochastic modes of operation of the dispersion model. The method is evaluated by computational simulations of a 3-d field experiment on atmospheric dispersion of ⁴¹Ar emitted routinely from a research reactor. Available measurements of fluence rate (photons flux) in air are assimilated in the Lagrangian dispersion model DIPCOT and the ⁴¹Ar emission rate is estimated. The statistical analysis shows that the model-calculated emission rates agree well with the real ones. In addition the model-predicted fluence rates at the locations of the sensors, which were not used in the data assimilation procedure are in better agreement with the measurements. The first evaluation results of the method presented in this study show that the method performs satisfactorily and therefore it is applicable in nuclear ERSs provided that more comprehensive validation studies will be performed.

  5. 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)

  6. Determination of dose conversion factors for external gamma radiation in dwellings; Determinacao de fatores de conversao de dose para radiacao gama externa em residencias

    Energy Technology Data Exchange (ETDEWEB)

    Maduar, Marcelo Francis

    2000-07-01

    The use of building materials containing natural radionuclides in dwelling construction may lead to an increment of both external and internal radiation exposure of the population. External exposure in dwellings arises from gamma-emitter radionuclides existing in the walls, floor and ceiling. Mathematical models can be used to predict external dose rates inside the room, provided the radionuclide concentration activities in dwelling constituents and the building geometry are known. In this work, a methodology and a computer code, called EDVOS, for theoretical evaluation of external gamma doses in the air, due to radionuclides present in the constituents of an hypothetical room, were developed. The room is modeled as three pairs of rectangular sheets with finite thickness. Evaluation of doses was performed through the application of a photon transport model, taking into account self-absorption and radiation buildup. The radionuclides were assumed to be uniformly distributed in the building materials. Calculations were performed for concrete walls and results are presented for {sup 40}K, {sup 226} Ra, and {sup 232}Th, taking into account, for dose calculations, all gamma emitters from {sup 226}Ra and {sup 232}Th decay chains. The response of the model to the input parameters was studied by varying each of them within a reasonable range of applicability, while leaving the other ones at fixed selected values. The results obtained showed a good agreement with those presented in the literature and with data obtained by running RESRAD-BUILD code. Dose conversions factors are presented in a form suitable for the use in radiological impact studies applied to practical situations. (author)

  7. Effects of low dose gamma irradiation on the germination and physiological activity of old red pepper (Capsicum annuum L.) seed

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Sung; Back, Myung Hwa; Lee, Hae Youn; Lee, Young Keun [KAERI, Daejeon (Korea, Republic of)

    2001-12-15

    To observe the stimulating effects of low dose gamma radiation on the germination and physiological activity of germinating seeds of old red pepper (Capsicum annuum L. cv, Jokwang and cv. Hongkwang), seeds were irradiated at the dose of 2{approx}50 Gy. The germination rate of irradiation group was higher than that of the control. Especially it was highest at the early stage of induction. The germination rate at 7 days after sowing in Jokwang and Hongkwang cultivar was high as 74% and 11% at 4 Gy and 8 Gy irradiation group, respectively. The seedling height of Jokwang cultivar was noticeably high at 4 Gy irradiation group and that of Hongkwang cultivar at 8 Gy Irradiation group. The protein contents of seedlings from seeds irradiated with low dose gamma radiation of Jokwang cultivar increased at the late stage of induction and that of Hongkwang cultivar at the early stage of induction. Catalase and peroxidase activities of seedlings from seeds irradiated with low dose gamma radiation of Jokwang cultivar increased at 4 Gy irradiation group and that of Hongkwang cultivar at 8 Gy irradiation group.

  8. Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

    Energy Technology Data Exchange (ETDEWEB)

    Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha, E-mail: haqnawaz@bzu.edu.pk [Bahauddin Zakariya University, Multan (Pakistan)

    2016-10-15

    Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

  9. Clinical improvement in feline herpesvirus 1 infected cats by oral low dose of interleukin-12 plus interferon-gamma.

    Science.gov (United States)

    Fiorito, Filomena; Cantiello, Antonietta; Granato, Giovanna Elvira; Navas, Luigi; Diffidenti, Carmine; De Martino, Luisa; Maharajan, Veeramani; Olivieri, Fabio; Pagnini, Ugo; Iovane, Giuseppe

    2016-10-01

    Feline herpesvirus 1 (FHV-1) is a widespread cat pathogen inducing rhinitis, conjunctivitis and corneal ulcers. To alleviate acute FHV-1-induced disease, antiviral agents are used often with antibiotics. But sometimes, these treatments, as well as conventional doses of cytokines have moderate efficacy and/or collateral effects. Herein we have investigated the effects of low dose interleukin (IL)-12 plus interferon (IFN)-gamma, prepared by Sequential Kinetic Activated (SKA), on the treatment of FHV-1 infection. Twenty-five, unvaccinated FHV-1-positive cats were recruited into a prospective, randomized, placebo-controlled, double-blinded clinical trial. Fifteen cats were treated for 6 months with oral low doses of SKA IL-12 plus IFN-gamma and 10 cats were treated with placebo. At 1, 6 and 12 months (follow-up) after the beginning of treatment, clinical assessment, PCR assay and blood count were carried out. At follow-up, in treated group, we observed significant (pcats (80%). In placebo, 10/10 cats were PCR-positive, with improvements (30%) or worsening (70%) in clinical signs. Blood values were normal in both groups. Our results show that the low dose therapy, based on activated solutions of IL-12 plus IFN-gamma, represents a novel approach to treat FHV-1 infection in cats. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Tiago L.; Filho, Joao A. [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil). Dept. de Fisica; Silva, Jose M