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Sample records for absorbed radiation dose

  1. An international intercomparison of absorbed dose measurements for radiation therapy

    Dose intercomparison on an international basis has become an important component of quality assurance measurement i.e. to check the performance of absorbed dose measurements in radiation therapy. The absorbed dose to water measurements for radiation therapy at the SSDL, MINT have been regularly compared through international intercomparison programmes organised by the IAEA Dosimetry Laboratory, Seibersdorf, Austria such as IAEA/WHO TLD postal dose quality audits and the Intercomparison of therapy level ionisation chamber calibration factors in terms of air kerma and absorbed dose to water calibration factors. The results of these intercomparison in terms of percentage deviations for Cobalt 60 gamma radiation and megavoltage x-ray from medical linear accelerators participated by the SSDL-MINT during the year 1985-2001 are within the acceptance limit. (Author)

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

    Perevertaylo V. L.

    2010-01-01

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

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

    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.

  4. Problems in radiation absorbed dose estimation from positron emitters

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

  5. Patient absorbed radiation doses estimation related to irradiation anatomy

    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

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

    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

  7. Space radiation absorbed dose distribution in a human phantom

    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

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

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

    1977-01-01

    Thin radiochromic dye films are useful for measuring large radiation absorbed doses (105–108 rads) and for high-resolution imaging of dose patterns produced by penetrating radiation beams passing through non-homogeneous media. Certain types of amino-substituted triarylmethane cyanides dissolved 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...... dose rate (1–1014 rad s−1). Upon irradiation of the film, the profile of the radiation field is registered as a permanent colored image of the dose distribution. Unlike most other types of dyed plastic dose meters, the optical density produced by irradiation is in most cases stable for periods of at...

  9. Biological indicators for radiation absorbed dose: a review

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

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

    Sudha Rana

    2010-01-01

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

  11. Assessment of population absorbed dose from external penetrating radiation in Beijing

    Gonad mean annual absorbed dose from external penetrating radiation for Beijing residents is 73.4 mrad/y of which the annual absorbed dose from cosmic ray is 27.1 mrad/y and that from natural radioactivity in building materials is 37.6 mrad/y. The construction of buildings and roads makes the annual absorbed dose change. The construction of buildings brings about an increase of 19.7 per cent in the annual absorbed dose. The construction of roads results in a reduction of 2.4%

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

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

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

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

    2013-06-01

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

  14. Advances in absorbed dose measurement standards at the australian radiation laboratory

    The applications of ionising radiation in the medical and industrial fields require both an accurate knowledge of the amount of ionising radiation absorbed by the medium in question and the capability of relating this to National and International standards. The most useful measure of the amount of radiation is the absorbed dose which is defined as the energy absorbed per unit mass. For radiotherapy, the reference medium is water, even though the measurement of the absorbed dose to water is not straightforward. Two methods are commonly used to provide calibrations in absorbed dose to water. The first is the calibration of the chamber in terms of exposure in a Cobalt-60 beam, followed by the conversion by a protocol into dose to water in this and higher energy beams. The other route is via the use of a graphite calorimeter as a primary standard device, where the conversion from absorbed dose to graphite to absorbed dose in water is performed either by theoretical means making use of cavity ionisation theory, or by experiment where the graphite calorimeter and secondary standard ionisation chamber are placed at scaled distances from the source of the radiation beam (known as the Dose-Ratio method). Extensive measurements have been made at Cobalt-60 at ARL using both the exposure and absorbed dose to graphite routes. Agreement between the ARL measurements and those based on standards maintained by ANSTO and NPL is within ± 0.3%. Absorbed dose measurements have also been performed at ARL with photon beams of nominal energy 16 and 19 MeV obtained from the ARL linac. The validity of the protocols at high photon energies, the validity of the methods used to convert from absorbed dose in graphite to absorbed dose in water and the validity of the indices used to specify the beams are discussed. Brief mention will also be made of the establishment of a calibration facility for neutron monitors at ARL and of progress in the development of ERP dosimetry

  15. Method for determination of ratio of absorbed doses created by different radiations from two sources

    The proposed method involves determination of ratio of absorbed doses in a mixed radiation field due to radiations from two different sources, provided that both radiations are of different LET, hence of a different quality factor. A detector used in the method is a tissue-equivalent recombination chamber. Shape of saturation curve of such a chamber depends on LET (on radiation quality). If the shapes of saturation curves are known for the radiations from two sources or for both components of a two-component radiation, then the actual ratio of absorbed dose components created simultaneously by these radiations in the mixed radiation field can be determined, performing relatively simple measurements of the ionization current at two different polarizing voltages applied to the chamber.

  16. Method for determination of ratio of absorbed doses created by different radiations from two sources

    Gryzinski, Michal A., E-mail: m.gryzinski@cyf.gov.p [Institute of Atomic Energy, 05-400 Otwock-Swierk (Poland); Zielczynski, Mieczyslaw [Institute of Atomic Energy, 05-400 Otwock-Swierk (Poland); Golnik, Natalia [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland)

    2010-12-15

    The proposed method involves determination of ratio of absorbed doses in a mixed radiation field due to radiations from two different sources, provided that both radiations are of different LET, hence of a different quality factor. A detector used in the method is a tissue-equivalent recombination chamber. Shape of saturation curve of such a chamber depends on LET (on radiation quality). If the shapes of saturation curves are known for the radiations from two sources or for both components of a two-component radiation, then the actual ratio of absorbed dose components created simultaneously by these radiations in the mixed radiation field can be determined, performing relatively simple measurements of the ionization current at two different polarizing voltages applied to the chamber.

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

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

  18. An absorbed dose microcalorimeter

    A graphite microcalorimeter is described for use as a primary standard of ionising radiation absorbed dose; its place in the hierarchy of Australian ionising radiation standards is discussed. A disc shaped absorber is supported on pins within three nested graphite jackets and an insulated vacuum vessel. Calibration heating is by thermistor, the feasibility of this was verified by computer modelling. Adiabatic and heat-flow modes of operation are described, and calculations of heat transfer between the various graphite parts are summarised. Carbon and water phantoms were built for the evaluation of correction factors for the microcalorimeter, and for the calibration of radiotherapy dosemeters. The microcalorimeter will be used as a working standard for the calibration of dosemeters in terms of absorbed dose for the x-ray, gamma-ray and electron radiotherapy beams commonly used in Australia today

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

    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.

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

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

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

    McLaughlin, W. L.; Miller, Arne; Fidan, S.; Pejtersen, K.; Pedersen, Walther Batsberg

    1977-01-01

    dose rate (1–1014 rad s−1). Upon irradiation of the film, the profile of the radiation field is registered as a permanent colored image of the dose distribution. Unlike most other types of dyed plastic dose meters, the optical density produced by irradiation is in most cases stable for periods of at...... 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...

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

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

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

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

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

    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...

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

    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)

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

    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)

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

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

    2014-07-01

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

  8. The design of a calorimetric standard of ionising radiation absorbed dose

    The design of a calorimetric working standard of ionising radiation absorbed dose is discussed. A brief history of the appropriate quantities and units of measurement is given. Detailed design considerations follow a summary of the relevant literature. The methods to be used to relate results to national standards of measurement are indicated, including the need for various correction factors. A status report is given on the construction and testing program

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

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

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

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

  11. Testing of the IAEA code: Absorbed dose determination at Co 60 gamma radiation

    At several Primary Standard Dosimetry Laboratories measurements of absorbed dose to water have been performed with ionization chambers of different types. These ionization chambers are calibrated against both, primary standards of air kerma and water absorbed dose. Using the formalism of the IAEA Code of Practice the absorbed dose to water in Co 60 gamma beams was derived and compared with direct measurements of water absorbed dose. This yields a very valid test of the IAEA Code. (author). 18 refs, 7 tabs

  12. Aquatic ecosystems of the Chernobyl NPP exclusion zone: dynamics of contamination, radiation absorbed doses, radiation effects

    The results of radioactive contamination dynamics in the main components of aquatic ecosystems and absorbed dose rate for hydrobionts within the Chernobyl accident exclusion zone has been analysed. Some cytogenetic and haematological effects of long-term irradiation on aquatic organisms as well as damage of higher aquatic plants by parasitic fungi and gall-producing arthropods have been considered. (authors)

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

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

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

    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.

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

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

    1983-04-01

    Biological data obtained principally with Fe-59 citrate are used with physical data to calculate radiation absorbed doses for ionic or weak chelate forms of Fe-52, Fe-55, and Fe-59, administered by intravenous injection. Doses are calculated for normal subjects, primary hemochromatosis (also called idiopathic or hereditary hemochromatosis), pernicious anemia in relapse, iron-deficiency anemia, and polycythemia vera. The Fe-52 doses include the dose from the Mn-52m daughter generated after injection of Fe-52. Special attention has been given to the dose to the spleen, which has a relatively high concentration of RBCs and therefore of radioiron, and which varies significantly in size in both health and disease. PMID:6339690

  16. About some aspects of absorbed and effective ionizing radiation dose computation of population under external and internal radiation influence

    The purpose of the investigation is to develop methods of dose assessment, absorbed by individual human organs, or effective dose of population, as well as to study factors effecting on uncertainties in their computation. The dose assessment for the Thyroid or other organ is based on retrospective information obtained from radioecological monitoring and according to the information about radioactive fallout's on the surface after each nuclear test, as well as the information about concrete living conditions of local population. The main parameter in proposed algorithms is gamma-radiation dose rate at open area, which is a result of direct measurements. When assessing internal radiation dose, in the course of inhalation, the whole period of local fallout's is taken into consideration. The developed method allows obtaining a systematic information describing irradiation of people by means of the radioactive traces, as well as tabulated information for model computations of internal and external radiation dose

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

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

  18. Absorbed radiation dose in plants of natural complexes in Belarus over the past 10 years following the Chernobyl accident

    An absorbed radiation dose in plant of the natural complexes in Belarus for 10 years following the Chernobyl accident was calculated. The data on dynamics of the exposure dose rate in the area for 10 years were used for calculating the absorbed dose due to external irradiation and the data on the specific activity of the plants due to incorporation of cesium 137 and strontium 90 were taken into consideration when calculating the absorbed dose due to internal irradiation. Maximal absorbed doses in plants (to 40 Gy) were fixed in the zone with the high density of contamination. It resulted in visible somatic damages of separated plant organs. The highest contribution to formation of absorbed doses of ionizing radiation in plants in the contaminated zones belongs to internal irradiation of plant organisms due to incorporated radionuclides, in particular cesium 137

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

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

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

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

    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.

  2. Standard Guide for Selection and Use of Mathematical Methods for Calculating Absorbed Dose in Radiation Processing Applications

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide describes different mathematical methods that may be used to calculate absorbed dose and criteria for their selection. Absorbed-dose calculations can determine the effectiveness of the radiation process, estimate the absorbed-dose distribution in product, or supplement or complement, or both, the measurement of absorbed dose. 1.2 Radiation processing is an evolving field and annotated examples are provided in Annex A6 to illustrate the applications where mathematical methods have been successfully applied. While not limited by the applications cited in these examples, applications specific to neutron transport, radiation therapy and shielding design are not addressed in this document. 1.3 This guide covers the calculation of radiation transport of electrons and photons with energies up to 25 MeV. 1.4 The mathematical methods described include Monte Carlo, point kernel, discrete ordinate, semi-empirical and empirical methods. 1.5 General purpose software packages are available for the calcul...

  3. The Australian Commonwealth standard of measurement for absorbed radiation dose. Part 1

    As an agent for the Commonwealth Scientific and Industrial Research Organisation, the Australian Nuclear Science and Technology Organisation is responsible for maintenance of the Australian Commonwealth standard of absorbed dose. This standard of measurement has application in radiation therapy dosimetry, which is required for the treatment of cancer patients. This report is the first in a series of reports documenting the absorbed dose standard for photon beams in the range from 1 to 25 MeV. The Urquhart graphite micro-calorimeters, which is used for the determination of absorbed dose under high energy photon beams, has been now placed under computer control. Accordingly, a complete upgrade of the calorimeter systems was performed to allow operation in the hospital. In this report, control and monitoring techniques have been described, with an assessment of the performance achieved being given for 6 and 18 MeV bremsstrahlung beams. Random errors have been reduced to near negligible proportions, while systematic errors have been minimized by achieving true quasi-adiabatic operation. 16 refs., 9 tabs., 11 figs

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

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

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

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

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

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

    2012-07-01

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

  7. Magnetic Resonance Imaging-Based Radiation-Absorbed Dose Estimation of 166Ho Microspheres in Liver Radioembolization

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

  8. Comparison of skin absorbed radiation dose in thyroid gland area during panoramic radiography and spiral tomography techniques

    Najmeh Akhlaghi

    2011-01-01

    Full Text Available Introduction: Thyroid gland is one of the critical organs during radiation in the head and neck region. The aim of this study was to compare absorbed radiation dose by skin in the thyroid area during spiral tomography and panoramic radiography by means of thermoluminance dosimetry (TLD.Materials and Methods: Thirty-six LiF (TLD-100 thermoluminescence dosimetry chips were utilized in this experimental in vitro study. One TLD chip was placed on the tube side and another was placed on the opposite side of the thyroid gland of a sliced anatomic Alderson head and neck phantom during panoramic radiography and spiral tomography. The dosimeters were read by a SOLARO 2A TLD reader twice followed by calculation of the absorbed dose. The results were analyzed by Wilcoxon’s test at a confidence interval of 95%.Results: The mean dose for screen-film panoramic radiographs was 34 µGy in the left thyroid and 39 on the right side. With spiral tomography the thyroid gland received a mean dose of 30‒71 µGy. There were no statistically significant differences in the mean thyroid doses between anterior and posterior spiral tomography and panoramic examination (p value > 0.05.Conclusion: Skin absorbed radiation dose of a tomographic examination, which includes four sections with a specific thickness, are almost comparable to that with a panoramic radiographic technique. Key words: Absorbed dose, Spiral tomography, Panoramic radiography.

  9. Influence of gamma radiation of indoor radon decay products on absorbed dose

    A survey of absorbed dose rate and indoor radon concentration in multi storey houses was carried out. The main source of radon in such houses is construction materials. There is a relationship between absorbed dose rate and indoor radon concentration. This relationship is rather complicated and different for different premises. It depends on the geometry of premises and other characteristics which influence the distribution of indoor radon daughters. Increment of absorbed dose rate per unit of increment of indoor radon concentration depends on the concentration of indoor radon, floor where premises are situated, geometry of premises. The results of this study might help to assess the dose due to indoor radon which originates from construction materials. (author)

  10. Absorbed dose measurements using TLDS in biological samples from beta radiation

    José Eduardo Manzoli

    2006-01-01

    Full Text Available Irradiation of samples in peculiar experimental apparatus, subject to radiation spread, requires a special evaluation of absorbed dose implanted to the sample. Indirect calibration of the irradiation source, obtained in a different apparatus, and the spread, usually of very difficult theoretical evaluation, can cause very serious measurement errors, sometimes reaching 50%. In this work, the procedure for dose evaluation in an apparatus for beta irradiation of samples, usually biological ones,is presented, making use of calibration curves, obtained by irradiation in advance of thermoluminescent detectors in air, and so irradiating them in the same position of the sample. An application in blood sample irradiation is also presented.A irradiação de amostras em arranjos experimentais peculiares sujeitos a espalhamento necessita de uma determinação própria da dose absorvida que a amostra irá receber. A calibração indireta da fonte de irradiação, que ocorre em arranjo diferente, e o espalhamento, geralmente de difícil estimativa teórica, podem causar erros de medição muito elevados, não raro atingindo 50%. Neste trabalho é apresentado o procedimento para determinação da dose absorvida em um arranjo para irradiação beta de amostras, normalmente biológicas, utilizando curvas de calibração obtidas pela irradiação de dosímetros termoluminescentes no ar, e os irradiando na mesma posição das amostras. É apresentado um exemplo de aplicação para amostra irradiada de sangue.

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

    This study aimed to validate a MOSFET dosemeter system for determining absorbed and effective doses (EDs) in the dose and energy range used in diagnostic radiology. Energy dependence, dose linearity and repeatability of the dosemeter were examined. The absorbed doses (ADs) were compared at anterior-posterior projection and the EDs were determined at posterior-anterior, anterior-posterior and lateral projections of thoracic imaging using an anthropomorphic phantom. The radiation exposures were made using digital radiography systems. This study revealed that the MOSFET system with high sensitivity bias supply set-up is sufficiently accurate for AD and ED determination. The dosemeter is recommended to be calibrated for energies <60 and >80 kVp. The entrance skin dose level should be at least 5 mGy to minimise the deviation of the individual dosemeter dose. For ED determination, dosemeters should be implanted perpendicular to the surface of the phantom to prevent the angular dependence error. (authors)

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

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

    2015-04-01

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

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

    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)

  14. Comparison of the standards of absorbed dose to water of the METAS and the BIPM for 60Co gamma radiation

    A comparison of the standards of absorbed dose to water of the Swiss Federal Office of Metrology and Accreditation (METAS), Switzerland and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co gamma radiation. The results show that the METAS and the BIPM standards for absorbed dose to water are in agreement, yielding a comparison result of 1.0001 for the mean ratio of the calibration coefficients for the transfer chambers, the difference from unity being within the combined standard uncertainty (0.0054). (authors)

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

    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....

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

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

  17. The MIRD method of estimating absorbed dose

    Weber, D.A.

    1991-01-01

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

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

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

    2010-07-01

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

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

    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.

  20. Detection limits of absorbed dose of ionizing radiation in molluscan shells as determined by e.p.r. spectroscopy

    The exposure of waters to ionizing radiation from radionuclides imprisoned in dumped nuclear waste containers, freed in nuclear submarine accidents or released in underwater magma eruptions are difficult to be evaluated by conventional radiometric methods. Ionizing radiation evokes stable paramagnetic centers in crystalline lattice of mineral components in bone skeletons of mammals and fishes as well as in exoskeletons of mollusca. They give rise in e.p.r. to specific, extremely stable signals which are proposed to be applied as indicators of radiation exposure levels. In the present study the e.p.r. detection limits of the dose of ionizing radiation absorbed in shells of fresh water and marine mollusca (selected species) have been estimated. It has been found that with fresh water mollusca the dose of 1-2 Gy can be detected, while the sea water mollusca by one order of magnitude lower, i.e. about 0.1 Gy. (author)

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

    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

  2. Simultaneos determination of absorbed doses due to beta and gamma radiations with CaSO4: Dy produced at Ipen

    Due to the Goiania radiological accident, it was necessary to develop urgently a dosimeter in order to evaluate, simultaneously, beta and gamma absorbed doses, due to 137Cs radiations. Therefore, the Dosimetric Material Production Laboratory of IPEN developed a simple, practical, light and low cost badge using small thickness (0,20mm) thermoluminescent CaSO4: Dy pellets produced by the same laboratory. This pellets are adequate for beta radiation detection. These dosimeters were worn by some IPEN technicians who worked in Goiania city, and were used to evaluate the external and internal contaminations presented by the accident victims interned at the Hospital Naval Marcilio Dias. (author)

  3. Estimation of radiation absorbed doses for 6-18F-L-DOPA in human based on rats biodistribution

    To estimate the radiation absorbed doses in humans due to intravenous administration of 6-18F-L-DOPA (18F-DOPA) based on rats biodistribution data and appraise the security of 18F-DOPA in humans. At 5, 30, 60, 90, 120 and 150 min after 18F-DOPA is injected into rats through a tail vein, the rats are killed by cervical fracture and biodistribution in rats are determined. Radiation dosimetry in humans are calculated on the base of activity distribution in rats and the standard MIRD method using radioactivity-time curves for humans. The kidney is the organ receiving highest dose of 22.9 pGy/Bq, the brain receives a dose of 11.8 pGy/Bq, and other organs receive doses between 9 and 18 pGy/Bq. The effective dose is estimated to be 20.5 pSv/Bq. The results demonstrate that human radiation dosimetry can be estimated to be 20.5 pSv/Bq. The results demonstrate that human radiation dosimetry can be estimated by the rats biodistribution data and provide an important data for clinical safe trial of 18F-DOPA

  4. Evaluation of absorbed dose rate and annual effective dose equivalent due to terrestrial gamma radiation in rocks in a part of Southwestern Nigeria

    The average outdoor absorbed dose rate in air and the average annual effective dose equivalent due to terrestrial gamma radiation from 40K, 238U and 232Th in rocks in Ondo and Ekiti States, Southwestern Nigeria have been evaluated from measurements of the concentrations of these radionuclides in this environmental material. The concentration measurements were obtained using a very sensitive gamma spectroscopic system consisting of a 7.6x7.6 cm NaI(Tl) scintillation detector coupled to a computerised ACCUSPEC installation. The average absorbed dose rate and average annual effective dose equivalent was found to be 8.33±2.76 nGy.h-1 and 8.7±2.9 μSv.y-1 respectively. (author)

  5. Evaluation of absorbed dose rate and annual effective dose equivalent due to terrestrial gamma radiation in rocks in a part of Southwestern Nigeria

    Ajayi, O.S

    2002-07-01

    The average outdoor absorbed dose rate in air and the average annual effective dose equivalent due to terrestrial gamma radiation from {sup 40}K, {sup 238}U and {sup 232}Th in rocks in Ondo and Ekiti States, Southwestern Nigeria have been evaluated from measurements of the concentrations of these radionuclides in this environmental material. The concentration measurements were obtained using a very sensitive gamma spectroscopic system consisting of a 7.6x7.6 cm NaI(Tl) scintillation detector coupled to a computerised ACCUSPEC installation. The average absorbed dose rate and average annual effective dose equivalent was found to be 8.33{+-}2.76 nGy.h{sup -1} and 8.7{+-}2.9 {mu}Sv.y{sup -1} respectively. (author)

  6. On the definition of absorbed dose

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

  7. Absorbed dose by a CMOS in radiotherapy

    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)

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

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

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

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

  10. Estimation of Absorbed Dose in Occlusal Radiography

    The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-210 Head and Neck Section R, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70 Kvp and 15 mA, 1/4 second (8 inch cone ) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In Mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

  11. Estimation of Absorbed Dose in Occlusal Radiography

    Yoo, Young Ah; Choi, Karp Shick [Dept. of Oral Radiology, College of Dentistry, Kyungpuk National University, Daegu (Korea, Republic of); Lee, Sang Han [Dept. of Oral and Maxillofacial Surgery, College of Dentistry, Kyungpook National University, Daegu (Korea, Republic of)

    1990-02-15

    The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-210 Head and Neck Section R, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70 Kvp and 15 mA, 1/4 second (8 inch cone) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In Mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

  12. [Absorbed doses in dental radiology].

    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. PMID:8966249

  13. Distribution of absorbed dose rate in air because of terrestrial gamma radiation in Miyako-jima, Okinawa Prefecture, Japan

    The absorbed dose rate in air because of terrestrial gamma radiation in Miyako-jima, an island that is part of Okinawa Prefecture in the subtropical region of Japan, was estimated at 637 points by in situ measurements with spectrometers equipped with 3''φ x 3''NaI(Tl) and 1''φ x 2''NaI(TL) scintillation detectors. The mean, minimum, and maximum dose rates were calculated to be about 79 nGy/h, 3 nGy/h, and 165 nGy/h, respectively. The correlation of the dose rate and geology showed that the high-rate areas (>100 nGy/h) and the distribution of the Holocene red soils (Onokoshi Clay) overlap each other. On the other hand, the low dose rates (<30 nGy/h) were mainly found in an outcrop of the Pleistocene Ryukyu Limestone, the main geologic element in the foundation of the red soils. Recent studies (e.g., Inoue et al., 1993) concluded that most of the red soils were not residuals from the base rocks, but of eolian dust ''Kosa (Yellow Sand)'' origin. These results strongly indicate that the dose rate in Miyako-jima has been enhanced as a result of eolian deposits transported mainly from the arid region of China since the last glacial epoch. (author)

  14. On the definition of absorbed dose

    Grusell, Erik

    2015-02-01

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

  15. Tumoral fibrosis effect on the radiation absorbed dose of 177Lu–Tyr3-octreotate and 177Lu–Tyr3-octreotate conjugated to gold nanoparticles

    The aim of this work was to evaluate the tumoral fibrosis effect on the radiation absorbed dose of the radiopharmaceuticals 177Lu–Tyr3-octreotate (monomeric) and 177Lu–Tyr3-octreotate–gold nanoparticles (multimeric) using an experimental HeLa cells tumoral model and the Monte Carlo PENELOPE code. Experimental and computer micro-environment models with or without fibrosis were constructed. Results showed that fibrosis increases up to 33% the tumor radiation absorbed dose, although the major effect on the dose was produced by the type of radiopharmaceutical (112 Gy-multimeric vs. 43 Gy-monomeric). - Highlights: • Fibrosis increases the radiation absorbed dose to the tumor. • Fibrosis increases the radiopharmaceutical residence time in the tumor. • The multimeric nature of the radiopharmaceuticals enhances the radiopharmaceutical retention

  16. A model study on the absorbed dose of radiation following respiratory intake of 238U3O8 aerosols

    Aerosols of depleted uranium oxides, formed upon high-energy impact of shells on hard targets during military operations, are able to disperse, reach the alveolar region of the lungs and be absorbed and distributed throughout various parts of the body. The absorbed particles are subjected to clearance in the upper respiratory tract, distribution to other body districts, dissolution and excretion. While the soluble forms of uranium are known to deliver a small dose of radiation to the body due to their homogeneous distribution and the low specific activity of 238U, ceramic particles exhibit a low dissolution rate and irradiate a limited volume of tissue for a long time with alpha particles with an energy of 4.267 MeV. The extent of the irradiated tissues depends on the radius of the particles and the total intake of uranium oxides. For the measured intake of U3O8 of a war veteran (15.51 μg) the number of particles ranges from 5.56x104 to 6.95x106 for sizes of 0.4-2.0 μm. Modelling the distribution of the particles between two compartments of the body, the averaged dose absorbed in 20 y by tissues surrounding the particles and within the range of the alpha particles varies from 6.8 mGy to 0.85 Gy for lungs and 8.1 mGy to 1.0 Gy for the lymph nodes, respectively. Correspondingly, due to the clearance and redistribution, the mass irradiated by 2.0-mm particles falls in 20 y from 6.06 mg to 0.94 μg in the lungs and grows from 0 to 1.0 mg in the lymph nodes. The estimated rate of formation of hydroxyl radicals upon radiolysis of water in the lungs and lymph nodes is 5.17x104 d-1 per cell after 1 y. (authors)

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

    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...

  18. Soil radioactivity and radiation absorbed dose rates at roadsides in high-traffic density areas in Ibadan metropolis, southwestern Nigeria

    The effect of ionising of ionising radiation on biological systems depends among other factors on time and place of exposure and population involved. Socio-economic factors in human daily activities have subjected humans to certain environmental health risks. In most cases the risk appears to be higher outdoors than indoors. In order to quantify the radiation exposure levels to individuals in the outdoors in areas with high human and vehicular densities, roadside soil samples were collected from major bus stops and round-about in the metropolis of Ibadan and were analysed for their activity concentration levels using gamma-ray spectrometry. The 40K activity concentration ranged between 96.1 and 336.5 Bq kg-1 with a mean of 219.8 ± 71.4 Bq kg-1; 238U was in the range of 10.2-40.7 Bq kg-1 with a mean of 20.3 ± 6.9 Bq kg-1 while that of 232Th ranged between 13.3 and 29.7 Bq kg-1 with a mean of 21.2 ± 5.3 Bq kg-1. The total gamma absorbed dose rates in air ranged between 17.2 and 41.8 nGy h-1 with an average of 32.0 ± 5.8 nGy h-1. The gamma absorbed dose rates at the roadsides in traffic density areas were found to be lower when compared with previously reported values in natural and undisturbed locations in non-traffic density areas in the city. (authors)

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

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

  20. The measuring of the absorbed dose in human tissue that underwent irradiation with ionizing radiation

    Bercea, S.; Nikolic, A.; Cenusa, C.; Celarel, A.

    2010-07-01

    Ionizing radiations are radiations of atomic origin (X) or nuclear origin (α, β, γ). They are composed of either subatomic particles (α, β) or electromagnetic waves (X, γ) which possess enough energy to remove electrons from the atoms and molecules of the medium with which particles interact. They thus generate ionizing processes. The effects that are produced by the interaction of the ionizing radiations with a particular medium (which could be human tissue) have different intensities depending on the nature of the incident radiations, on the rate in which these radiations release energy to the medium and on the total amount of energy released to the medium. For this reason, the energy released by a particular type of ionizing radiations to a particular type of medium has become of great interest both for researchers and for specialists who deal with using ionizing radiations in different fields, such as the biomedical one. The aim of the present paper is to briefly present some of the aspects connected to the way certain quantities are defined, quantities which are specific to the interaction of ionizing particles with the medium they pass through and which are also connected to the energy released in the medium. The paper also describes methods of measuring these quantities.

  1. Absorbed doses from temporomandibular joint radiography

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

    1985-06-01

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

  2. Absorbed doses from temporomandibular joint radiography

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

  3. Absorbed doses and radiation damage during the 11 years of LEP operation

    Schönbacher, H

    2004-01-01

    During the 11 years of operation of the Large Electron Positron Collider (LEP), synchrotron radiation was emitted in the tunnel. This ionizing radiation induced degradation in organic insulators and structural materials, as well as in electronics. Annual dosimetric measurements have shown that the level of radiation increased with the ninth power of the beam energy. During the machine shut-downs and at the end of the operation, samples of rigid and flexible polymeric insulators (magnet-coil resins and cable insulations) were taken out and checked for their integrity. The test results are compared with the results obtained during the qualification of the materials, 12 to 15 years ago. At that time, lifetime predictions were done; they are now compared with the real time aged materials.

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

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

  5. Radiation-absorbed doses and energy imparted from panoramic tomography, cephalometric radiography, and occlusal film radiography in children

    The absorbed doses and energy imparted from radiographic examinations of children, using panoramic tomography (PTG), cephalometric radiography (CPR), and maxillary frontal occlusal overview (FOO), were examined. The absorbed dose at various sites of the head were measured with TL dosimeters in a phantom and in patients. The energy imparted was calculated from measurements of areal exposure using a planparallel ionization chamber. The maximum absorbed doses for panoramic tomography were located around the lateral rotation center, for cephalometric radiography in the left (tube side) parotid region, and for frontal occlusal radiography in the nose. The absorbed doses in the eyes, thyroid gland, and skin are discussed and compared with previous reports and, for the most part, are found to be in agreement. The mean energy imparted from all three examination methods is 5 mJ with about 57 percent from panoramic, 33 percent from cephalometric, and 10 percent from frontal occlusal examinations. The energy imparted from cephalometric radiography can be reduced to about 10 percent with the use of an improved examination technique, leaving panoramic tomography responsible for contributing about 80 percent of the total energy imparted

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

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

  7. Absorber for terahertz radiation management

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

    2015-12-08

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

  8. Quality assurance technique for absorbed dose distribution in external radiation therapy with non-physical wedges in consideration of the character of the imaging plate

    The film dose distribution method is used for profile measurements of non-physical wedges, because three-dimensional automatic control water phantoms cannot be used. Recently, many hospitals have adopted computed radiography (CR) systems in preference to automatic developing processors and films. This may allow use of automatic processors to be discontinued. In this study, a beam was irradiated to an Imaging Plate (IP), and then IP was exposed to a fixed amount of light with fading, and we then measured the off-center ratio (OCR) absorbed dose distribution in external radiation therapy with non-physical wedge. This was compared with the OCR measured with an ionization chamber dosimeter. It was consequently possible for IP to approximate the value measured by the ionization chamber dosimeter by using a metal filter. This method offers a simple quality assurance technique for absorbed dose distribution in external radiation therapy with non-physical wedges in consideration of the character of the IP. (author)

  9. Absorbed Doses to Patients in Nuclear Medicine

    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: 11C- acetate, 11C- methionine, 18F-DOPA, whole antibody labelled with either 99mTc, 111In, 123I or 131I, fragment of antibody, F(ab')2 labelled with either 99mTc, 111In, 123I or 131I and fragment of antibody, Fab' labelled with either 99mTc, 111In, 123I or 131I. The absorbed dose estimates for these substances have been made from published biokinetic information. For other substances of interest, e.g. 14C-urea (children age 3-6 years), 14C-glycocholic acid, 14C-xylose and 14C-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

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

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

  11. Evaluation of natural gamma radiation and absorbed gamma dose in soil and rocks of Perambalur district (Tamil Nadu, India)

    The activity concentrations and absorbed gamma dose of primordial radionuclides 238U, 232Th and 40K were determined employing γ-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg-1 for 238U, 66 Bq kg-1 for 232Th and 340.3 Bq kg-1 for 40K as compared to mean values for rock samples (238U-8.0 Bq kg-1; 232Th-65.1 Bq kg-1; 40K-199.1 Bq kg-1). The mean absorbed gamma dose rate for soil (61.4 nGy h-1) marginally exceeded the prescribed limit of 55 nGy h-1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h-1. The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg-1) than in rock (20.0 Bq kg-1). However, these values were lower than the limit (370 Bq kg-1) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district. (author)

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

    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.

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

    Christensen, Poul

    1986-01-01

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

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

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

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

    Christensen, Poul

    1986-01-01

    The techniques available at present for personal monitoring of doses from external beta and low energy photon radiation are reviewed. The performance of currently used dosimetry systems is compared with that recommended internationally, and developments for improving the actual performance are...

  16. Determination of absorbed dose in reactors

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

  17. 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

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

  18. The expression revealing variation trend about radiation resistance of aromatic polymers serving in nuclear environment over absorbed dose

    For polymeric materials applied in nuclear environment, the macroscopic properties usually remain unchanged after irradiation for several years or decades up to a threshold dose at which the deterioration of materials begins to take place. In this paper, the general radiation response of aromatic polymers is firstly reviewed and discussed. Then percolation theory is employed innovatively to elucidate the critical phenomenon over the service life for polymeric materials with high radiation resistance. For a better quantitative evaluation, a novel two-parameter radiation resistance model is proposed by the method of analogy between two nuclear-related phenomena. Six epoxy systems are employed from the published literatures to verify the novel model and the result shows that it is reliable and helpful in not only estimating the radiation damage over the service period but also multi-objective optimum design of polymeric materials. - Highlights: • Radiation resistance of aromatic polymers was studied. • Percolation theory was employed to elucidate the critical phenomenon. • A novel two-parameter radiation resistance model was proposed and verified

  19. Estimation of Absorbed Dose Rate and Collective Effective Dose Equivalent Due to Gamma Radiation from Selected Radionuclides in Soil in Ondo and Ekiti State, South-Western Nigeria

    The concentrations of natural radionuclides, namely 40K, 238U and 232Th, in surface soils in Ondo and Ekiti States, south-western Nigeria have been measured using a very sensitive gamma ray spectroscopic system consisting of a 760 mm x 760 mm NaI(Tl) scintillation detector coupled to a Canberra Series 10 Plus multichannel analyser. The mean absorbed dose rate, annual effective dose equivalent and the collective effective dose equivalent in these states have been estimated from the measured concentrations of the radionuclides, which are 0.015 ± 0.008 μGy.h-1, 18.4 μSv.y-1 and 73.6 man.Sv.y-1 respectively. (author)

  20. Estimation of Absorbed Dose Rate and Collective Effective Dose Equivalent Due to Gamma Radiation from Selected Radionuclides in Soil in Ondo and Ekiti State, South-Western Nigeria

    Ajayi, I.R.; Ajayi, O.S

    1999-07-01

    The concentrations of natural radionuclides, namely {sup 40}K, {sup 238}U and {sup 232}Th, in surface soils in Ondo and Ekiti States, south-western Nigeria have been measured using a very sensitive gamma ray spectroscopic system consisting of a 760 mm x 760 mm NaI(Tl) scintillation detector coupled to a Canberra Series 10 Plus multichannel analyser. The mean absorbed dose rate, annual effective dose equivalent and the collective effective dose equivalent in these states have been estimated from the measured concentrations of the radionuclides, which are 0.015 {+-} 0.008 {mu}Gy.h{sup -1}, 18.4 {mu}Sv.y{sup -1} and 73.6 man.Sv.y{sup -1} respectively. (author)

  1. Investigation of the reliability and accuracy of thermoluminescence dosimetry for the determination of absorbed doses of radiation from dental x-ray machines

    A method for acceptably accurate measurement of doses of absorbed radiation to certain parts of the body during dental x-ray examinations was developed. This method used lithium fluoride discs. Eighteen Harshaw thermoluminescent dosimeters (TLDs) were selected, as they gave the most consistent readings when subjected to a constant source of radiation. These TLDs were subjected to measured exposures of radiation from a cobalt source and a dental x-ray machine, the beam quality and symmetry of which were determined. The TLDs were read on an Eberline model TLR-6 TLD reader and the results plotted graphically against the measured exposure readings obtained from a Farmer dosemeter. The relationship of the measured exposure to the corresponding TLD readings was found to be linear and it was shown that the mean or median figures for each series of TLD readings could be relied upon to an accuracy of 90%. 26 refs., 7 figs., 4 tabs

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

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

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

    Gunalp, Bengul

    2015-07-01

    Myocardial perfusion imaging (MPI) is one the most contributing nuclear medicine technique to the annual population dose. The purpose of this study is to compare radiation-absorbed doses to the patients examined by conventional cardiac SPECT (CSPECT) camera and ultrafast cardiac (UFC) camera with cadmium-zinc-telluride (CZT) solid-state detectors. Total injected activity was reduced by 50 % when both stress and rest images were acquired and by 75 % when only stress images were taken with UFC camera. As a result of this, the mean total effective dose was found significantly lower with UFC camera (2.2 ± 1.2 mSv) than CSPECT (7.7 ± 3.8 mSv) (p < 0.001). Further dose reduction was obtained by reducing equivocal test results and unnecessary additional examinations with UFC camera. Using UFC camera, MPI can be conveniently used for the detection of coronary artery disease (CAD) much less increasing annual population radiation dose as it had been before. PMID:25848109

  4. 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

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent, for isotropic exposure of an adult male and an adult female to helions (3He2+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Calculations were performed using Monte Carlo transport code MCNPX 2.7.C and BodyBuilderTM 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP), and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 2%. The greatest difference, 62%, occurred at 100 MeV. Published by Oxford Univ. Press on behalf of the U.S. Government 2010. (authors)

  5. 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

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons (3H+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilderTM 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV. Published by Oxford Univ. Press on behalf of the US Government 2010. (authors)

  6. Determination of absorbed dose in water

    This report describes the experimental work carried out for the determination of absorbed dose in water in the energy of X-rays generated at potentials of 100 kV to 250 kV. Two small cavity ionization chambers were used for this experiment. The results of these measurements were compared with the results obtained by using NPL Secondary Standard Therapy level X-ray exposure meter. The related problems of converting an exposure quantity into absorbed dose in water an absorbed dose in water have also been discussed. (Orig./A.B.)

  7. Definition of spatial distribution of the absorbed dose of γ-radiation source 60Co for installation URI

    The study of energy distribution among different objects (as well as forms of energy absorption in them) being researched in radiation chemistry, radiobiology and micro-dosimetry has become one of the actual problems recently. Impossibility of practical parameters definition makes the theoretical solution of the problem one of the major tasks in this field. The most probable primary processes of interaction the γ-radiation with subjects of inquiry are Compton dispersion and photoeffect. Therefore in this work on the base of Compton dispersion and photoeffect an entire spectrum of dispersive γ-quanta and δ-electrons formed in the result of monoenergetic γ-quanta interaction with different media (gaseous, liquid, solid) is calculated. The flux density of γ-quanta in any part of cylindrical working volume is determined. Section of interaction of monoenergetic γ-quanta with the medium is calculated by the equation of Klein-Nishina-Tamm and Bete. Depending on energy spectrum of δ-electrons obtained in the result of the interaction their average energy is determined by means of stepping method. Interaction process cross-sectional of δ-electrons with the medium is determined by the equation of Grizinsky. The account proceeded up to value of δ-electrons energy approached to value of medium ionization energy. Dose rate received by a calculation way on the formula: P = k·φi (k - the constant of transition from density of a flow to a dose) to within ±5 % coincides with experimental values. The account was carried out on the basis of installations available in Section of Radiation Researches National Academy of Science of Azerbaijan, and on the basis of the mathematical program Mathcad

  8. Evaluation of the absorbed dose in odontological computerized tomography

    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

  9. Radiation dose in vertebroplasty

    Mehdizade, A.; Lovblad, K.O.; Wilhelm, K.E.; Somon, T.; Wetzel, S.G.; Kelekis, A.D.; Yilmaz, H.; Abdo, G.; Martin, J.B.; Viera, J.M.; Ruefenacht, D.A. [Neuroradiology DRRI, Geneva University Hospital, Rue Micheli-du-Crest 24, 1211, Geneva 14 (Switzerland)

    2004-03-01

    We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11 consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256 mGy outside and 0.01-0.47 mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5 mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurements. (orig.)

  10. A novel parameter, cell-cycle progression index, for radiation dose absorbed estimation in the premature chromosome condensation assay

    The calyculin A-induced premature chromosome condensation (PCC) assay is a simple and useful method for assessing the cell-cycle distribution in cells, since calyculin A induces chromosome condensation in various phases of the cell cycle. In this study, a novel parameter, the cell-cycle progression index (CPI), in the PCC assay was validated as a novel bio-marker for bio-dosimetry. Peripheral blood was drawn from healthy donors after informed consent was obtained. CPI was investigated using a human peripheral blood lymphocyte (PBL) ex vivo irradiation (60Co-gamma rays: ∼0.6 Gy min-1, or X ray: 1.0 Gy min-1; 0-10 Gy) model. The calyculin A-induced PCC assay was performed for chromosome preparation. PCC cells were divided into the following five categories according to cell-cycle stage: non-PCC, G1-PCC, S-PCC, G2/M-PCC and M/A-PCC cells. CPI was calculated as the ratio of G2/M-PCC cells to G1-PCC cells. The PCC-stage distribution varied markedly with irradiation doses. The G1-PCC cell fraction was significantly reduced, and the G2/M-PCC cell fraction increased, in 10-Gy-irradiated PBL after 48 h of culture. CPI levels were fitted to an exponential dose-response curve with gamma-ray irradiation [y = 0.6729 + 0.3934 exp(0.5685D), r = 1.0000, p < 0.0001] and X-ray irradiation [y = -0.3743 + 0.9744 exp(0.3321D), r = 0.9999, p < 0.0001]. There were no significant individual (p = 0.853) or gender effects (p = 0.951) on the CPI in the human peripheral blood ex vivo irradiation model. Furthermore, CPI measurements are rapid (< 15 min per case). These results suggest that the CPI is a useful screening tool for the assessment of radiation doses received ranging from 0 to 10 Gy in radiation exposure early after a radiation event, especially after a mass-casualty radiological incident. (authors)

  11. Whole-body biodistribution, radiation absorbed dose, and brain SPET imaging with [123I]5-I-A-85380 in healthy human subjects

    The biodistribution of radioactivity after the administration of a new tracer for α4β2 nicotinic acetylcholine receptors (nAChRs), [123I]5-iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380), was studied in ten healthy human subjects. Following administration of 98±6 MBq [123I]5-I-A-85380, serial whole-body images were acquired over 24 h and corrected for attenuation. One to four brain single-photon emission tomography (SPET) images were also acquired between 2.5 and 24 h. Estimates of radiation absorbed dose were calculated using MIRDOSE 3.1 with a dynamic bladder model and a dynamic gastrointestinal tract model. The estimates of the highest absorbed dose (μGy/MBq) were for the urinary bladder wall (71 and 140), lower large intestine wall (70 and 72), and upper large intestine wall (63 and 64), with 2.4-h and 4.8-h urine voiding intervals, respectively. The whole brain activity at the time of the initial whole-body imaging at 14 min was 5.0% of the injected dose. Consistent with the known distribution of α4β2 nAChRs, SPET images showed the highest activity in the thalamus. These results suggest that [123I]5-I-A-85380 is a promising SPET agent to image α4β2 nAChRs in humans, with acceptable dosimetry and high brain uptake. (orig.)

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

    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)

  13. 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

    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)

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

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

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

    Radiation-induced reduction, radiolysis of copper sites and the effect of pH value together with the concomitant geometrical distortions of the active centres were analysed in several fungal (C. gallica) laccase structures collected at cryotemperature. This study emphasizes the importance of careful interpretation when the crystallographic structure of a metalloprotein is described. X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O2. In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UV–Vis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O2 reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account

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

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

    2012-05-01

    Radiation-induced reduction, radiolysis of copper sites and the effect of pH value together with the concomitant geometrical distortions of the active centres were analysed in several fungal (C. gallica) laccase structures collected at cryotemperature. This study emphasizes the importance of careful interpretation when the crystallographic structure of a metalloprotein is described. X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O{sub 2}. In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UV–Vis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O{sub 2} reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account.

  17. Development and comparison of computational models for estimation of absorbed organ radiation dose in rainbow trout (Oncorhynchus mykiss) from uptake of iodine-131

    This study develops and compares different, increasingly detailed anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ absorbed radiation dose and dose rates from 131I uptake in multiple organs. The models considered are: a simplistic geometry considering a single organ, a more specific geometry employing additional organs with anatomically relevant size and location, and voxel reconstruction of internal anatomy obtained from CT imaging (referred to as CSUTROUT). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling, and combined with estimated activity concentrations, to approximate dose rates and ultimately determine cumulative radiation dose (μGy) to selected organs after several half-lives of 131I. The different computational models provided similar results, especially for source organs (less than 30% difference between estimated doses), and whole body DCFs for each model (∼3 × 10−3 μGy d−1 per Bq kg−1) were comparable to DCFs listed in ICRP 108 for 131I. The main benefit provided by the computational models developed here is the ability to accurately determine organ dose. A conservative mass-ratio approach may provide reasonable results for sufficiently large organs, but is only applicable to individual source organs. Although CSUTROUT is the more anatomically realistic phantom, it required much more resource dedication to develop and is less flexible than the stylized phantom for similar results. There may be instances where a detailed phantom such as CSUTROUT is appropriate, but generally the stylized phantom appears to be the best choice for an ideal balance between accuracy and resource requirements. - Highlights: • Computational models (phantoms) are developed for rainbow trout internal dosimetry. • Phantoms are combined with empirical models for 131I uptake to estimate dose. • Voxel and stylized phantoms predict similar

  18. 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

    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)

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

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

    2016-01-01

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

  20. 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

    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)

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

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

  2. Electron absorbed dose measurements in LINACs by thermoluminescent dosimeters

    In this work, electron absorbed doses measurements in radiation therapy (RT) were obtained. Radiation measurements were made using thermoluminescent dosimeters of calcium sulfate doped with dysprosium (CaSO4:Dy) and zirconium oxide (ZrO2). TL response calibration was obtained by irradiating TLDs and a Farmer cylindrical ionization chamber PTW 30013 at the same time. Each TL material showed a typical glow curve according to each material. Both calcium sulfate doped with dysprosium and zirconium oxide exhibited better light intensity to high energy electron beam compared with lithium fluoride. TL response as a function of absorbed dose was analyzed. TL response as a function of high energy electron beam was also studied. - Highlights: • Experimental results of ZrO2 irradiated by high energy electron beam. • Dosimetric characteristics of CaSO4:Dy were obtained under high energy electron effect. • Absorbed dose in electron beam was determined by TL phosphors. • Absorbed dose could be measured by TL phosphors and the results suggest that phosphors are good candidate for absorbed dose determining

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

    Kubota, Yoshihisa; Takahashi, Hiroyuki; Watanabe, Yoshito; Fuma, Shoichi; Kawaguchi, Isao; Aoki, Masanari; Kubota, Masahide; Furuhata, Yoshiaki; Shigemura, Yusaku; Yamada, Fumio; Ishikawa, Takahiro; Obara, Satoshi; Yoshida, Satoshi

    2015-04-01

    The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium ((134)Cs and (137)Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h(-1) (1.2 mGy d(-1)), even 3 years after the accident. This dose rate exceeds 0.1-1 mGy d(-1) derived consideration

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

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

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

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

  6. Bone marrow and thyroid absorbed doses from mammography

    Breast dose from mammography has been estimated by various investigators, because of the established effectiveness of mammography in early screening for breast cancer and the relatively high sensitivity of the breast to radiation carcinogenesis. Nevertheless, to our knowledge, there is no available information in the literature about absorbed doses from mammography to organs other than the breast. The absorbed doses to the red bone marrow in the sternum and to the thyroid, due to scattered radiation from mammographic examinations, have been measured using a Plexiglas upper-body phantom and thermoluminescent dosemeters. Their dependence on several parameters has also been examined. It is necessary to emphasize that this work is still in progress. (author)

  7. Photon absorbed dose: the UK standard

    Since 1988, the primary standard for megavoltage photon dosimetry in the UK has been a graphite calorimeter. The routine calibration of secondary standard ionisation chambers has been provided by NPL directly in terms of absorbed dose to water since then, with users following the 1990 IPSM Code of Practice. Comparisons of the primary standard with NPL's reference ionisation chambers have been carried out annually, and the calibration service has been offered in the spring and autumn each year, for 60Co γ-rays and 4 MV to 19 MV X-rays. The data generated have been analysed and the results of this analysis are presented here. The long-term stability of the NE 2561 chamber, and its value in maintaining the standard of absorbed dose is demonstrated. The utility of TPR as a beam quality parameter is discussed, and the resulting ambiguity in chamber calibration is quantified. The conversion of dose from graphite to water is summarized, and changes in the basis of the NPL absorbed dose standard over the last seven years are described

  8. Some comments on the concept of absorbed dose

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

  9. Recent regional key comparison results for air kerma and absorbed dose to water in X-rays and 60Co radiation

    beam qualities, - new comparisons involving the radiation of the brachytherapy sources in terms of absorbed dose to water in the vicinity of the seeds, - new Dw comparisons for high energy accelerator beams to have more information about the different high energy accelerator beams

  10. Absorbed dose evaluation by SISCODES code, kerma and fluence deviations

    Radiotherapy is a common treatment of cancer. Radiotherapy exposes the patient to a radiation field, producing ionization, and absorbed dose. A precise dose calculation and the ability to execute the irradiation on the patient are necessary in order to avoid serious injuries on the surrounding health tissue, thus, the maximum acceptable absorbed dose error from the prescribed and applied is about 5%. The doses on radiotherapy are usually calculated by superimposition experimental dose profile, namely PDP, which is experimentally measured in a water simulator. Moreover, the radiation interaction with human body tissues depends on the chemical composition and the tissue density, which means the anthropomorphism and anthropometric of the human being. This paper evaluates the deviation of calculated value of kerma, induced by human body heterogeneities. To do this job two thorax voxel models created on SISCODES (one filled with various tissues other filled with water) were applied. The result of simulations permits two different comparisons. One is the ratio between tissues kermas and water kerma. Another is the ratio between human phantom fluence, where exists radiation scatter and reflection, and water phantom fluence. The reconstructed pictures of studied regions showing the calculated ratios, and graphs of the ratios versus energy of each tissue are shown. The dose ratio deviations obtained are, in some situations, larger than the acceptable 5% point out serious miscalculation of doses for some spatial regions on the human body. (author)

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

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

  12. Application of cytogenetic methods for estimation of absorbed dose

    Accumulated data on the practical application of cytogenetic technique to evaluate the absorbed dose for men involved in activities to eliminate the effects of the Chernobyl NPP accident were analyzed. Those data were compared with the results of cytogenetic studies conducted in other Russia regions affected by radiation impacts (Muslyumovo settle., Chelyabinsk Region, the Altay Territory settlements near the Semipalatinsk test range) and with the examination results of population of the territory of the Three Mile Island NPP (Island, Pennsylvania, USA) where in 1975 the nuclear accident took place. The cytogenetic studies were carried out using the standard analysis technique evaluating the frequency of unstable aberrations of chromosomes (UA) and using FISH-technique designed to evaluate the frequency of stable aberrations of chromosomes. It was pointed out that UA-technique could not be used efficiently for the retrospective evaluation of the absorbed doses with no clear idea correlating the nature and the rate of elimination with cell life time, especially, in case of small doses of irradiation. Analysis of the stable translocation using FISH-technique enabled to evaluate the absorbed dose within 8-9 years following the accident. The range of the absorbed doses of the examined persons varied from the background ones up to 1 Gy

  13. Radiation dose estimates for radiopharmaceuticals

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

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

    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.

  15. Absorbed radiation by various tissues during simulated endodontic radiography

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

  16. Absorbed radiation by various tissues during simulated endodontic radiography

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

    1989-06-01

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

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

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

    2016-01-01

    The aim of this research was to investigate the fetal doses of pregnant patients undergoing conformal radiotherapy or intensity-modulated radiation therapy (IMRT) for breast cancers. An Alderson Rando phantom was chosen to simulate a pregnant patient with breast cancer who is receiving radiation therapy. This phantom was irradiated using the Varian Clinac DBX 600 system (Varian Medical System, Palo Alto, CA) linear accelerator, according to the standard treatment plans of both three-dimensional conformal radiation therapy (3-D CRT) and IMRT techniques. Thermoluminescent dosimeters were used to measure the irradiated phantom׳s virtually designated uterus area. Thermoluminescent dosimeter measurements (in the phantom) revealed that the mean cumulative fetal dose for 3-D CRT is 1.39cGy and for IMRT it is 8.48cGy, for a pregnant breast cancer woman who received radiation treatment of 50Gy. The fetal dose was confirmed to increase by 70% for 3-D CRT and 40% for IMRT, if it is closer to the irradiated field by 5cm. The mean fetal dose from 3-D CRT is 1.39cGy and IMRT is 8.48cGy, consistent with theoretic calculations. The IMRT technique causes the fetal dose to be 5 times more than that of 3-D CRT. Theoretic knowledge concerning the increase in the peripheral doses as the measurements approached the beam was also practically proven. PMID:26831923

  18. Red bone marrow doses, integral absorbed doses, and somatically effective dose equivalent from four maxillary occlusal projections

    Phantom measurements of red bone marrow (RBM) doses, integral absorbed doses, and somatically effective dose equivalent (SEDE) from four different maxillary occlusal projections are presented. For each projection, different combinations of focus-skin distances and tube potentials were compared with regard to the patient's radiation load. The axial incisal view produced the highest patient exposures, with a maximum red bone marrow dose of 122.5 microGy/exposure, integral absorbed dose of 8.6 mJ/exposure, and SEDE values of 39.6 microSv/exposure. The corresponding values from the frontal, lateral occlusal, and tuber views ranged between 4% and 44% of the axial incisal view values for the integral absorbed dose and SEDE values, and between 0.3% and 3% for the red bone marrow doses. Increasing the focus-skin distance from 17.5 cm to 27 cm is accompanied by a 24% to 30% reduction in integral absorbed dose. Increasing the tube potential from 50 kV to 65 kV likewise results in a 23% reduction in absorbed energy

  19. Red bone marrow doses, integral absorbed doses, and somatically effective dose equivalent from four maxillary occlusal projections

    Berge, T.I.; Wohni, T.

    1984-02-01

    Phantom measurements of red bone marrow (RBM) doses, integral absorbed doses, and somatically effective dose equivalent (SEDE) from four different maxillary occlusal projections are presented. For each projection, different combinations of focus-skin distances and tube potentials were compared with regard to the patient's radiation load. The axial incisal view produced the highest patient exposures, with a maximum red bone marrow dose of 122.5 microGy/exposure, integral absorbed dose of 8.6 mJ/exposure, and SEDE values of 39.6 microSv/exposure. The corresponding values from the frontal, lateral occlusal, and tuber views ranged between 4% and 44% of the axial incisal view values for the integral absorbed dose and SEDE values, and between 0.3% and 3% for the red bone marrow doses. Increasing the focus-skin distance from 17.5 cm to 27 cm is accompanied by a 24% to 30% reduction in integral absorbed dose. Increasing the tube potential from 50 kV to 65 kV likewise results in a 23% reduction in absorbed energy.

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

    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...

  1. Registration of radiation doses

    In Finland the Radiation and Nuclear Safety Authority (STUK) is maintaining the register (called Dose Register) of the radiation exposure of occupationally exposed workers in order to ensure compliance with the principles of optimisation and individual protection. The guide contains a description of the Dose Register and specifies the responsibilities of the party running a radiation practice to report the relevant information to the Dose Register

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

    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.

  3. Estimation of absorbed organ doses and effective dose based on body mass index in digital radiography

    With the introduction of digital radiography, patients undergoing radiographic procedures are subject to being overexposed to radiation. Therefore, it is necessary to estimate the absorbed organ dose and the effective dose, which are significant for patient health, along with body type. During chest radiographic examinations conducted in 899 patients for screening, the absorbed dose of the 13 major organs, the average whole-body dose, and two effective doses weighted by factors published in ICRP 60 and ICRP 103 were calculated on the basis of patient information such as height, weight and examination condition, including kilovolt potential, focus-skin distance and entrance surface dose (ESD), using a PC-based Monte Carlo program simulation. It was found that dose per unit ESD had a tendency to decrease with body mass index (BMI). In particular, the absorbed dose for most organs was larger at high voltages (140 kVp) than at low voltages (120 kVp, 100 kVp). In addition, the effective dose which was based on ICRP 60 and ICRP 103 also represented the same tendency in respect of BMI and tube voltage. (authors)

  4. Calculation of the absorbed dose for contamination in skin imparted by beta radiation through the Varskin code modified for 122 isotopes of interest for nuclear medicine, nuclear plants and research

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

  5. Calculation of 131I-ortho-iodohippurate absorbed kidney dose: A literature review

    Extensive information has been made available relative to the physical aspects necessary for calculation of radiation absorbed dose from radiopharmaceuticals. A similar data base for the biological factors involved in these calculations has not been documented as thoroughly. The authors present an extensive literature review for the radiation absorbed dose of 131I-ortho-iodohippurate and discuss the rationale for adjusting previously accepted values with new biodistribution information

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

    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)

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

    Marília Tavares Christóvão

    2010-08-01

    Full Text Available OBJETIVO: Propõe-se avaliar os perfis de dose em profundidade e as distribuições espaciais de dose para protocolos de radioterapia ocular por prótons, a partir de simulações computacionais em código nuclear e modelo de olho discretizado em voxels. MATERIAIS E MÉTODOS: As ferramentas computacionais empregadas foram o código Geant4 (GEometry ANd Tracking Toolkit e o SISCODES (Sistema Computacional para Dosimetria em Radioterapia. O Geant4 é um pacote de software livre, utilizado para simular a passagem de partículas nucleares com carga elétrica através da matéria, pelo método de Monte Carlo. Foram executadas simulações computacionais reprodutivas de radioterapia por próton baseada em instalações pré-existentes. RESULTADOS: Os dados das simulações foram integrados ao modelo de olho através do código SISCODES, para geração das distribuições espaciais de doses. Perfis de dose em profundidade reproduzindo o pico de Bragg puro e modulado são apresentados. Importantes aspectos do planejamento radioterápico com prótons são abordados, como material absorvedor, modulação, dimensões do colimador, energia incidente do próton e produção de isodoses. CONCLUSÃO: Conclui-se que a terapia por prótons, quando adequadamente modulada e direcionada, pode reproduzir condições ideais de deposição de dose em neoplasias oculares.OBJECTIVE: The present study proposes the evaluation of the depth-dose profiles and the spatial distribution of radiation dose for ocular proton beam radiotherapy protocols, based on computer simulations in nuclear codes and an eye model discretized into voxels. MATERIALS AND METHODS: The employed computational tools were Geant4 (GEometry ANd Tracking Toolkit and SISCODES (Sistema Computacional para Dosimetria em Radioterapia - Computer System for Dosimetry in Radiotherapy. Geant4 is a toolkit for simulating the passage of particles through the matter, based on Monte Carlo method. Computer simulations

  8. Utilization of thermoluminescent dosemeters for determination of exposure or absorbed dose in a radiation gamma or X radiation field with unknown spectral distribution

    Having in view the choice of the best pair of dosemeters to be used in the 'Tandem' method, the main response characteristics of LiF:Mg, Ti, Li2B4O7:Mn, CaSO4Dy, CaF2:Mn and CaF2:Dy thermoluminescent dosemeters and also some critical parameters in their calibration and evaluation processes were studied. Three different physical forms of TLD's were investigated: hot pressed chips, disc teflon dosemeters and glass mini TLD's. Their calibration factors were obtained for the energy of Cobalt-60 gamma rays. Their energy dependences normalized to 60Co radiation were determined using spectral width as parameter. 'Tandens' formed by all TLD's evaluated were compaired. (E.G.)

  9. Determination of Absorbed Dose Using a Dosimetric Film

    This paper presents the absorbed dose measurements by means of the irradiated dosimetric reference films. The dose distributions were made by MULTIDATA film densitometer using RTD-4 software, in INFLPR Linear Accelerator Department

  10. Radiation doses to Finns

    The estimated annual radiation doses to Finns have been reduced in the recent years without any change in the actual radiation environment. This is because the radiation types have been changed. The risk factors will probably be changed again in the future, because recent studies show discrepancies in the neutron dosimetry concerning the city of Hiroshima. Neutron dosimetry discrepancy has been found between the predicted and estimated neutron radiation. The prediction of neutron radiation is calculated by Monte Carlo simulations, which have also been used when designing recommendations for the limits of radiation doses (ICRP60). Estimation of the neutron radiation is made on the basis of measured neutron activation of materials in the city. The estimated neutron dose beyond 1 km is two to ten, or more, times as high as the predicted dose. This discrepancy is important, because the most relevant distances with respect to radiation risk evaluation are between 1 and 2 km. Because of this discrepancy, the present radiation risk factors for gamma and neutron radiation, which rely on the Monte Carlo calculations, are false, too. The recommendations of ICRP60 have been adopted in a few countries, including Finland, and they affect the planned common limits of the EU. It is questionable whether happiness is increased by adopting false limits, even if they are common. (orig.) (2 figs., 1 tab.)

  11. Thyroid absorbed dose using TLDs during mammography

    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)

  12. Thyroid absorbed dose using TLDs during mammography

    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)

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

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

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

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

  15. Radiation doses from residual radioactivity

    requires knowing the location of the person to within about 200 m from the time of the explosion to a few weeks afterwards. This is an effort that might be comparable to the present shielding study for survivors. The sizes of the four exposed groups are relatively small; however, the number has been estimated only for those exposed to fallout in the Nishiyama district of Nagasaki. Okajima listed the population of Nishiyama as about 600 at the time of the bomb. No figures are available for the other three groups. The individual exposures from residual radiation may not be significant compared with the direct radiation at the time of the bomb. On the other hand, individuals with potential exposure from these sources are dubious candidates for inclusion in a cohort that was presumably not exposed. For comparison with organ doses estimated in other parts of this program, the exposure estimates are converted to absorbed dose in tissue. The first conversion of exposure to absorbed dose in air uses the factor rad in air 0.87 x exposure in R. UNSCEAR uses an average combined factor of 0.7 to convert absorbed dose in air to absorbed dose in tissue for the whole body. This factor accounts for the change in material (air to tissue) and for backscatter and the shielding afforded by other tissues of the body. No allowance for shielding by buildings has been included here. The cumulative fallout exposures given above become absorbed doses in tissue of 12 to 24 rad for Nagasaki and 0.6 to 2 rad for Hiroshima. The cumulative exposures from induced radioactivity become absorbed doses in tissue of 18 to 24 rad for Nagasaki and about 50 rad for Hiroshima. (author)

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

    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

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

    The purpose of this work is to develop an alternative method to determine the absorbed dose and effective energy of photons with unknown spectral distributions. It includes a 'tandem' system that consists of two thermoluminescent dosemeters with different energetic dependence. LiF: Mg, Ti, CaF2: Dy thermoluminescent dosemeters and a Harshaw 3500 reading system are employed. Dosemeters are characterized with 90Sr-90Y, calibrated with the energy of 60Co and irradiated with seven different qualities of x-ray beams, suggested by ANSI No. 13 and ISO 4037. The answers of each type of dosemeter are adjusted to a function that depends on the effective energy of photons. The adjustment is carried out by means of the Rosenbrock minimization algorithm. The mathematical model used for this function includes five parameters and has a gauss and a straight line. Results show that the analytical functions reproduce the experimental data of the answers, with a margin of error of less than 5%. The reason of the answers of the CaF2: Dy and LiF: Mg, Ti, according to the energy of the radiation, allows us to establish the effective energy of photons and the absorbed dose, with a margin of error of less than 10% and 20% respectively

  18. Design and development of radiation absorber for sighting beam line

    During the commissioning of Indus-2 , it is necessary to view the synchrotron radiation that will be emanating from the dipole exit ports. The 100 beam line from dipole 11 was earmarked for sighting beam line. The synchrotron radiation power density would be around 340 watts on the photon absorber inside the radiation absorber module, at the specified beam power of Indus-2. The beam striking on this photon absorber produces x-rays and Bremsstrahlung radiation. These are to be stopped and absorbed by radiation absorber. The photon absorber and the radiation absorber are integrated in a single vacuum chamber and actuated by a pneumatic cylinder connected using a bellow. Radiation absorber was needed to isolate the diagnostic components and to protect them from radiation a well as heat when they were not in use. The paper describes the design, calculation and development of the dynamic photon cum radiation absorber. The ultimate vacuum performance is also described. (author)

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

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

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

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

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

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

    2013-11-01

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

  2. Specification of absorbed dose for reporting a therapeutic irradiation

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

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

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

  4. Estimation of terrestrial air-absorbed dose rate from the data of regional geochemistry database

    This paper presents an estimation of air-absorbed dose rate from the data of K2O, U and Th content from Chinese regional geochemical database. A total of 421 group original data of combined samples in Zhongshan City (ZSC), Guangdong Province and south China were extracted from the national geochemical database. Estimated average value of air-absorbed dose rate is 139.4 nGy h-1 in the granite area and 73.7 nGy h-1 in the sedimentary area. The level of air-absorbed dose rate is closely related with the surface lithology. Estimated mean air-absorbed dose rate approximates to the measured average value by a portable plastic scintillator dosemeter in Zhuhai City were bordered with ZSC. The results show that the pre-evaluation of ionizing radiation level using regional geochemical data is feasible. (author)

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

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

  6. Evaluation of absorbed dose in Gadolinium neutron capture therapy

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

    2015-01-01

    Gadolinium neutron capture therapy (GdNCT) is used for treatment of radioresistant malignant tumors. The absorbed dose in GdNCT can be divided into four primary dose components: thermal neutron, fast neutron, photon and natural gadolinium doses. The most significant is the dose created by natural gadolinium. The amount of gadolinium at the irradiated region is changeable and depends on the gadolinium delivery agent and on the structure of the location where the agent i...

  7. Absorbed doses to patients from angioradiology

    The aim of study was to know patients doses exposes when three different procedures of angioradiology were carried out. The explorations considered were drainage biliary, varicocele embolization and dacriocistography made in the Radiodiagnostic Service at the University Hospital of Canary Islands, Tenerife (Spain). In total 14 patients were studied. The measurements were made using large area transmission ionisation chamber which gives the values of Dose Area Product (DAP). In addition, thermoluminescent dosimeters type TLD-100 were used in anthropomorphic phantom in order to obtain values of organ doses when the phantom was submitted to the same procedures rather than the actual patients. Furthermore, the Effdose program was used to estimate the effective doses in the procedures conditions. The values for DAP were in the range of 70-300 for drainage biliary, 43-180 for varicocele embolization and 1.4-9 for dacriocistography. The organ doses measured with TLD-100 were higher than the corresponding values estimated by Effdose program. The results for varicocele embolization were higher than other published data. In the case of drainage biliary procedure, the values were closed to other published results. It was not possible to find data for dacriocistography from other authors. (author)

  8. In vivo dosimetry for head and neck carcinoma: determination of target absorbed dose from entrance and exit absorbed dose measurements

    Farhat, L.; Daoud, J. [Service de radiotherapie carcinologique, CHU Habib-Bourguiba, 3029 Sfax (Tunisia); Besbes, M. [Service de radiotherapie carcinologique, Institut Salah-Azaiz, Boulevard du 9-avril-Bab-Saadoun, 1006 Tunis (Tunisia); Bridier, A. [Service de radiophysique, Institut Gustave-Roussy, 39 rue Camille-Desmoulins, 94805 Villejuif Cedex (France)

    2011-04-15

    The aims of this work were to measure the entrance and exit dose for patient treated for head and neck tumors. The target absorbed dose was determined from the exit and entrance dose measurement. Twenty patients were evaluated. The results were compared to the calculated values and the midline dose was determinate and compared with the prescribed dose. 80 entrance doses and 80 exit doses measurements were performed. The average difference from expected values was 1.93% for entrance dose (SD 1.92%) and -0.34% for exit dose (SD 4.1%). The target absorbed dose differed from prescribed dose values by 2.94% (1.97%) for the results using the Noel method and 3.34% (SD: 2.29%) with the Rizzotti method. The total uncertainty budget in the measurement of the absorbed entrance and exit dose with diode, including diode reading, correction factors and diode calibration coefficient, is determined as 3.02% (1 s). Simple in vivo dose measurements are an additional safeguard against major setup errors and calculation or transcription errors that were missed during pre-treatment chart check. (authors)

  9. Low chronic radiation doses

    In the context of the Chernobyl and Fukushima accidents where large territories have been contaminated durably and as consequence where local populations are submitted to chronic low radiation doses, IRSN (French institute for radiation protection and nuclear safety) has led various studies to assess the impact of chronic low doses. Studies about the effects of uranium on marine life show that the impact is strongly dependent on the initial state of the individual (zebra Danio rerio fish). The studies about the impact of chronic low doses due to cesium and strontium contamination show different bio-accumulations: 137Cs is found in the animal's whole body with higher concentrations in muscles and kidneys while 90Sr is found almost exclusively in bones and it accumulates more in female mice than in males. The study dedicated to the sanitary impact of chronic low doses on the workers of the nuclear industry shows a higher risk for developing a leukemia, a pleural cancer or a melanoma but no correlation appears between doses and the appearance of the pleural cancer or the melanoma. (A.C.)

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

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

  11. Phantoms for calculations of absorbed organ dose

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

  12. Doses from radiation exposure

    Menzel, H G

    2012-01-01

    Practical implementation of the International Commission on Radiological Protection's (ICRP) system of protection requires the availability of appropriate methods and data. The work of Committee 2 is concerned with the development of reference data and methods for the assessment of internal and external radiation exposure of workers and members of the public. This involves the development of reference biokinetic and dosimetric models, reference anatomical models of the human body, and reference anatomical and physiological data. Following ICRP's 2007 Recommendations, Committee 2 has focused on the provision of new reference dose coefficients for external and internal exposure. As well as specifying changes to the radiation and tissue weighting factors used in the calculation of protection quantities, the 2007 Recommendations introduced the use of reference anatomical phantoms based on medical imaging data, requiring explicit sex averaging of male and female organ-equivalent doses in the calculation of effecti...

  13. Eye lens dosimetry for interventional procedures – Relation between the absorbed dose to the lens and dose at measurement positions

    This study investigated the relationship between the absorbed dose to the lens of the eye and the absorbed dose at different measurement positions near the eye of interventional radiologists. It also visualised the dose distribution inside the head, both when protective eyewear were used and without such protection. The best position for an eye lens dosimeter was found to be at the side of the head nearest to the radiation source, close to the eye. Positioning the dosimeter at the eyebrow could lead to an underestimation of the lens dose of as much as 45%. The measured dose distribution showed that the absorbed dose to the eye lenses was high compared to the other parts of the head, which stresses the importance of wearing protective eyewear. However, many models of eyewear were found to be deficient as the radiation could slip through at several places, e.g. at the cheek. The relationship between the absorbed dose to the lens and the kerma-area-product (PKA) delivered to the patient was also studied.

  14. Absorbed doses calculation in dental diagnosis

    Theoretical teaching guide practices, it explains the measures of prevention that should be applied during the exhibitions to the radiation, as much for the patient as for the operator and the assistant. It doesn't seek the text books in no way, but upgrading them. it has for object, to integrate the modern contributions that come from the mensuration of the dosimetry and to establish the risk, that is subjected the patient and the operator to an inadequate irradiation

  15. Measurement of dose speed absorbed in depth imparted by sources external secondary patterns of beta radiation. Part 1 Measurement of dose speed absorbed in the surface of soft fabric for isotopes of 90Sr/90Y, 147Pm and 204TI

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

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

    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)

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

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

  18. Estimation of the absorbed dose in gamma irradiated food containing bone by electron spin resonance spectroscopy

    The use of electron spin resonance (ESR) spectroscopy to accurately evaluate the absorbed dose to radiationprocessed bones (and thus meats) is examined. The exposure of foodstuffs containing bone to a dose of ionizing radiation results in the formation of long lived free radicals which give rise to characteristics ESR signals. The yield of radicals was found to be proportional to absorbed dose. Additive re-irradiation of previously irradiated bone was used to estimate the absorbed dose in the irradiated chicken bone. Simple non-linear rational equation was found to fit to the data and yields good dose estimates for irradiated bone in the range of doses (1.0 - 5.0 kGy). Decay of the ESR signal intensity was monitored at different dose levels (2.0 and 7.0 kGy) up to 22 days. The absorbed dose in irradiated chicken (2.Om 3.0 and 6.0 kGy) was assessed at 2, 6 and 12 days after irradiation. Relatively good results were obtained when measurements were made within the following days (up to 12 days) after irradiation. The ability of the dose additive method to provide accurate dose assessments is tested here

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

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

  20. Dose absorbed by technologists in positron emission tomography procedures with FDG

    The objective of this work was to evaluate radiation doses delivered to technologists engaged in different tasks involving positron emission tomography (PET) studies with FDG (fluorodeoxyglucose). This investigation was performed in two French nuclear medicine departments, which presented significant differences in their arrangements and radiation safety conditions. Both centers administered about 300 MBq per PET/CT study, although only one of them is a dedicated clinical PET center. Dose equivalent Hp(10) and skin dose Hp(0.07) were measured using Siemens electronic personnel dosimeters. For assessment dose absorbed by hands during drawing up of tracer and injection into the patient, a Polimaster wristwatch gamma dosimeter was employed. Absorbed dose and the time spent during each investigated task were recorded for a total of 180 whole-body PET studies. In this report, the methodology employed, the results and their radioprotection issues are presented as well as discussed. (author)

  1. Peculiarities of absorbed dose forming in some wild animals in Chornobyl,y exclusion zone

    Based on field researches conducted in the exclusion zone of the Chernobyl nuclear power plant in the years after the accident, identified the peculiarities of formation absorbed doses in animals of different taxonomic and ecological groups that live in conditions of radioactive contamination of ecosystems. Was shown importance of consideration of radiation features on wild animals according to their life cycle, conditions and ways of life. Was displayed data about the importance of different types of irradiation according to the period of stay the animals in the ground, in burrows and nests. Was reviewed the questions about value of external and internal radiation in absorbed dose of different types of wildlife. Was shown the results of the calculation of the absorbed dose of bird embryos from egg shell

  2. Absorbed dose in the full-mouth periapical radiography, panoramic radiography, and zonography

    The objective of this study was to evaluate the possibility of substitution of the zonography for the full-mouth periapical radiography in aspect of radiation protection. Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses at brain, skin above the TMJ, parotid gland, bone marrow in the mandibular body, and thyroid gland during the full-mouth periapical radiography, panoramic radiography, and zonography were measured. From the zonography, the absorbed doses to the brain, the skin over the TMJ, and the parotid gland were relatively high, but the absorbed doses to the bone marrow in the mandibular body and, especially, the thyroid gland were very low. The zonography can be an alternative to the full-mouth periapical radiography in aspect of radiation protection.

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

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

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

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

  5. Norwegian system for implementing the IAEA code of practice based on absorbed dose to water

    In 2001 the Nordic secondary standards dosimetry laboratories (SSDLs) recommended the use of absorbed dose to water as the quantity for the calibration standard and code of practice in radiotherapy.The code of practice adopted was IAEA Technical Reports Series No. 398. The Norwegian system for implementation includes the 60Co calibration of SSDL and hospital dosimeters in terms of absorbed dose to water at the Norwegian SSDL and on-site visits to every clinic teaching the new code and performing dose measurements. Comparisons of the Norwegian Radiation Protection Authority 60Co absorbed dose to water calibration at the Finnish SSDL with the French primary standards dosimetry laboratory showed agreement within 0.4%.The on-site visit measuring system compared with the Finnish on-site equipment agreed within 0.6%.The on-site visits were welcomed, and demonstrated the need for external dosimetry audits to improve the local implementation of the code of practice. (author)

  6. Implementation of an absorbed dose postal QA programme for radiosurgery

    Radiosurgery is becoming a well accepted method for the treatment of small intra cranial benign lesions and neoplasic tumours. It can be delivered using multiple sources of 60Co gamma rays (i.e. Gamma knife) or using high energy photons, typically 6 MV, produced by clinical linear accelerators. The main objective of this work was to develop, test, and implement a Postal System of Quality Assurance of the absorbed dose applicable specifically to radiosurgery. Due to the specificity of the radiation field including the steep dose gradients, several measuring systems were necessary in order to guarantee the required dose accuracy. The ionization chamber (0,125 cm3/ PTW-Model 31010), thermoluminescent mini dosimeters (TLD), film, and mini Alanina dosimeters were selected. The dosimeters were calibrated against a PTW ionization dosimeter previously calibrated at the PTW secondary standards. The postal evaluation system consist of a main cylindrical acrylic phantom, with 16 cm of length and 21 cm of diameter, and four smaller cylindrical (C1-C4) inserts with 10 cm of length and 7 cm of diameter with the following specific characteristics: - C1 contains a small air volume with 2 cm of diameter that simulates the target with 3 air micro spheres with a diameter of 3 mm; - C2 contains five cylindrical rods where the mini TLDs with 2 mm of diameter and 0,5 mm of length were inserted and placed 5, 15, and 35 mm from the centre; - C3 contains five cylindrical rods where the alanine dosimeters with 1 mm of diameter and 2 mm of length were inserted at distances similar to those of the TLDs; - C4 contains an oncology film (X Omat-V) placed inside. In addition, a set of forms for data register and written procedures were sent to the participating institutions. A total dose of 25 Gy is requested to be delivered at the target. The overall management procedure is described, and the three main phases of the procedure are as follows: 1) An evaluation was made of the coordinate system of

  7. A system for 3-D absorbed dose measurements with tissue-equivalence for thermal neutrons

    A ferrous sulphate gel with a proper composition to thermalise epithermal neutrons with tissue equivalence with brain tissue gives the possibility of making phantoms which act as a continuous dosimeter for the gamma radiation, with the possibility of 3-D dose determination. If in the phantom a volume of gel containing 10B (in the amount typical for BNCT) is set, information on the absorbed dose in the tumour site may also be drawn. ((orig.))

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

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

    2010-01-15

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

  9. System for selective individual measurement of absorbed doses of gamma radiation and neutrons in mixed field. Portable individual sensor used in this system

    The system includes at least a sensor including two ionization chambers, each one in a different body, equipped with an electrometer and at least a transparent zone allowing visualization of movable part of the electrometer. One of the two bodies is sensitive to gamma radiation, while the other to both gamma and neutron radiations in fixed proportions; it is equipped also with a reading device common to the two sensors including at least an optical system able to give the image of the movable part of the two bodies on the sensitive part of at least one photo-electric detector

  10. Calorimeter measurements of absorbed doses at the heavy water enriched uranium reactor

    Application of calorimetry measurements of absorbed doses was imposed by the need of good knowledge of the absorbed dose values in the reactor experimental channels. Other methods are considered less reliable. The work was done in two phases: calorimetry measurements at lower reactor power (13-80 kW) by isothermal calorimeter, and differential calorimeter constructions for measurements at higher power levels (up to 1 MW). This report includes the following four annexes, papers: Isothermal calorimeter for reactor radiation monitoring, to be published; Calorimeter dosimetry of reactor radiation, presented at the Symposium about nuclear fuel held in april 1961; Radiation dosimetry of the reactor RA at Vinca, published in the Bull. Inst. Nucl. Sci. 1961; Differential calorimeter for reactor radiation dosimetry

  11. Identification and absorbed dose determination in irradiated kiwi by electron paramagnetic resonance

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

  12. The effect of latex maturity on the absorbed dose for preparing RVNRL of optimum tensile strength

    This paper present the results of the studies on the effects of using latex of different maturity periods, between 0 to 15 weeks on gamma irradiation dose require to prepare RVNRL of optimum tensile strength. Absorbed dose to prepare RVNRL of optimum tensile strength, molecular weight between cross-links and cross-link density were found to be influenced by the maturity of the latex used in the studies. With respect to optimum tensile strength and absorbed dose, latex of about six weeks maturity was found most suitable and economical for radiation vulcanization process. Using latex either with or without added secondary preservative the optimum tensile strength was determined at an absorbed of 8 kGy. However, the optimum tensile strength of RVNRL prepared from latex contained added secondary preservative was found to be higher than the optimum tensile strength of RVNRL prepared from latex without secondary preservative

  13. Study of absorbed dose distribution to high energy electron beams

    The depth absorbed dose distribution by electron beams was studied. The influence of the beam energy, the energy spread, field size and design characteristics of the accelerator was relieved. Three accelerators with different scattering and collimation systems were studied leading todifferent depth dose distributions. A theoretical model was constructed in order to explain the increase in the depth dose in the build-up region with the increase of the energy. The model utilizes a three-dimensional formalism based on the Fermi-Eyges multiple scattering theory, with the introduction of modifications that takes into account the criation of secondary electrons. (Author)

  14. Absorbed dose estimation and prediction irradiation effects in tumor-bearing mice under radionuclide therapy

    Full text: As the sizes of mouse organ are comparable with the range of the high-energy beta particles emitted by the radionuclides commonly used in radionuclide therapy a significant amount of beta radiation emitted could be imparted to the adjacent tissues. The often assumption that beta particles are fully-absorbed at the emission site is not satisfied and cross-irradiation should be included into the dose estimation formulas. Keeping in mind that the radiation effects are correlated with the absorbed dose in the target the inclusion of cross-irradiation in the dose estimation must be evaluated. The MIRD's formulation was used to perform absorbed dose calculation in mice using absorbed fractions previously reported for 131I, 90Y and 177Lu. Two approaches were considered: a) cross irradiation when a fraction of beta particles emitted can escape from the organ source and, b) full self- irradiation when the beta particles are considered fully absorbed at the emission site. The formulation of linear-quadratic model was readapted to be used in the radionuclide therapy. Treatment with a single administration in mice was simulated and radiation effects on tumor, bone marrow and kidneys under the assumption of cross-irradiation were predicted. A biphasic repair kinetics was considered in the calculation of irradiation effects on kidneys. Typical published biokinetic data for radiopharmaceutical assayed in mice and radiobiological parameters were used in the calculations. The influence of cross irradiation condition was diverse for the tissues analyzed here. The absorbed dose values in kidneys calculated for both methods were no significantly different for low energies, but variations around to 40-50% (over or under-estimation) in absorbed dose were obtained for high energies. Approximately a 30% of the beta radiation emitted from bone will cross irradiates the bone marrow. For injected activities values higher than 10MBq (300μCi), as a single injection, the

  15. Photon spectrum and absorbed dose in brain tumor

    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)

  16. Photon spectrum and absorbed dose in brain tumor

    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)

  17. Reconstruction of the composition of the Chernobyl radionuclide fallout and external radiation absorbed doses to the population in areas of Russia

    The results of reconstruction of the radionuclide composition of the Chernobyl fallout in the territories of Russia is presented. Reconstruction has been carried out by means of statistical analysis of the gamma spectrometry data on 2867 soil samples collected in the territories of Ukraine, Byelarus and Russia from 1986 to 1988. To verify the data, aggregated estimates of the fuel composition of the 4th block at the moment of the accident (available from the literature) have been used, as well as the estimates of activity released to the atmosphere. As a result, correlation and regression dependences have been obtained between the activities of the radionuclides most contributing to the dose (137Cs, 134Cs, 131I, 140Ba, 140La, 95Zr, 95Nb, 103Ru, 106Ru, 141Ce, 144Ce, 125Sb). Statistically significant regression relations between different pairs of radionuclides (including analysis of the 'noise' contribution to the data) depending on the distance between the point of sample collection and the power station are presented for the 'north-east track' - the northern part of the 30 km zone and southern part of the Gomel 'district (Byelarus) and the Briansk, Kaluga, Tula and Orel districts (Russia). A methodology is also described for reconstructing space-time characteristics of the contamination of the territories by major dose-forming radionuclides released from the Chernobyl NPP 4th unit. (Author)

  18. National pattern for the realization of the unit of the dose speed absorbed in air for beta radiation. (Method: Ionometer, cavity of Bragg-Gray implemented in an extrapolation chamber with electrodes of variable separation, exposed to a field of beta radiation of 90Sr/90Y)

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

  19. Internal Dosimetry Protocol to Determine Incidental Radiation Dose Absorbed by an Infant, due to the Incorporation of Gallium-67 in Breast Milk

    Within the protocol of quality in radiation protection designed in the service of nuclear medicine, taking into account the patients who will receive radionuclides and radiopharmaceuticals for diagnosis and therapy and their families. Despite the forecast, there is the possibility that incidental exposures occur in patients studied with dosimetry virtual or real. This case illustrates how to proceed and investigate in a study where a mother was administered gallium 67 (Ga-67) intravenously for staging of lymphoma and not properly followed the recommendation to temporarily suspend breastfeeding. When the Ga-67 is administered to a nursing mother, it has high concentration in breast milk, which creates a risk to the baby if inadvertently fed

  20. Radiation dose assessment for building material

    A mathematical model for radiation dose assessment for building materials based on attenuation and build up for gamma rays of the natural emitters was studied in this work. This was done by calculate the air absorbed dose from elemental volume and integrate over the total wall volume, which uniformed density and activity concentration. The used form of the build-up is a mixing of exponential and linear form for Berger model [1]. To convert absorbed dose to effective dose for all natural emitter (include 137Cs in case of fallout), the dose rate conversion factors which were reported in UNSCEAR (1993) Report [2] and U. S. NCRP (1987) [3] was used. These factors are 0.7 Sv/Gy for adult and 0.8 Sv/Gy for children. A computer program for calculating the absorbed and the annual effective dose was prepared in MATLAB language. The program is applicable for wall or room building materials when walls consist of one or two layers. The obtained results were compared with published studies. (author)

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

    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...

  2. Description and evaluation of a calibration procedure for the quantity absorbed dose to water

    A working standard for the quantity absorbed dose to water in a 60Co gamma radiation field has been established at the National Laboratory at the Swedish Radiation Protection Institute. In this report a description is given of the measurement set up and results from an evaluation of the calibration procedure are presented. Repeated measurements indicate a very good reproducibility in the measurement set up used for calibration. The combined uncertainty in the calibration factor for a therapy ionization chamber for the quantity absorbed dose to water at a water depth of 5 g·cm-2 in a 60Co gamma radiation field is estimated to be 0,50% (one standard deviation)

  3. Status of air kerma and absorbed dose standards in India

    maintained as primary standards for protection level and brachytherapy measurements of Ir-192, Cs-137 and Co-60 sources. These chambers are made of high purity reactor-grade graphite of density 1700 kg/m3. The three chambers have different wall thickness, the external diameters of all the chambers being equal. A reference standard in the form of a re-entrant chamber developed at BARC, calibrated against this primary standard was intercompared with a reference standard from M.D Anderson Centre, Houston, U.S.A and the results showed a good agreement. Recently one of the chambers was used for the Cs-137 intercomparison with IAEA and showed an agreement of better than ± 1%. 3. Primary Standard for X-rays - the free air chamber (FAC): This facility is utilized in conjunction with a Philips RT-250 X-ray machine for calibrating secondary standard dosemeters at different X-ray qualities in the 75 to 250 kV range. The total uncertainty in the realization of air kerma is around ±1% using the free air chamber. Accuracy of calibration of the secondary standards is estimated to be better than ±2%. The FAC has been intercompared via transferable transfer standards with FACs at BIPM (1971), BNM (France) RCL (Canada) and Kriss (Korea), which showed good agreement within ±1% after necessary correction for the spectral differences in X-ray beams. BARC is just now taking part in intercomparisons of X-ray air kerma calibration factors organised by Institute of Nuclear Energy Research (INER), Taiwan under Asia Pacific Metrology Programme. In addition to the above-mentioned primary standards, the SSDL is also maintaining the following secondary standards. For air kerma measurements at Co-60 gamma energy, ionisation chambers of Exradin A3, NE2571, NE2577 and Victoreen 415 types are calibrated and maintained. For Co-60 radiation dose to water measurements, NE 2571 and NE 2577 chambers calibrated at BIPM in terms of ND,W are maintained. For air kerma at medium energy x-rays, chambers of the type

  4. MEASUREMENT OF MICROWAVE RADIATION ABSORBED BY BIOLOGICAL SYSTEMS, 2, ANALYSIS BY DEWAR-FLASK CALORIMETRY

    Free-field power density has long been used as an index of energy dosing in studies of biological effects of microwave radiation. However, this method of quantifying dose can lead to considerable error if it is used as an index of the rate of energy actually being absorbed by a s...

  5. The Monte Carlo simulation of the absorbed dose in quartz

    Chen Shaowen [School of Physics Science and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275 (China) and Electron Engineering Department, Dongguan University of Technology, Dongguan 523808 (China)], E-mail: siumon@163.com; Liu Xiaowei; Zhang Chunxiang; Tang Qiang [School of Physics Science and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275 (China)

    2009-05-15

    Regeneration irradiation is a necessary procedure in TL or OSL dating protocol. The accuracy of measuring the absorbed dose is one of the important factors in dating. Since a beta source is often used in the regeneration irradiation process, the size of the quartz sample, pressure of nitrogen gas and the material of the sample holder may cause significant uncertainties in delivering the absorbed dose. In this work, the effects of the size of the quartz sample, the pressure of nitrogen gas and the material of the sample holder are simulated using the Monte Carlo method, and the uncertainties are discussed in these cases. The results show that they need to be considered in the dating.

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

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

  7. Simple dose verification system for radiotherapy radiation

    The aim of this paper is to investigate an accurate and convenient quality assurance programme that should be included in the dosimetry system of the radiotherapy level radiation. We designed a mailed solid phantom and used TLD-100 chips and a Rexon UL320 reader for the purpose of dosimetry quality assurance in Taiwanese radiotherapy centers. After being assembled, the solid polystyrene phantom weighted only 375 g which was suitable for mailing. The Monte Carlo BEAMnrc code was applied in calculations of the dose conversion factor of water and polystyrene phantom: the dose conversion factor measurements were obtained by switching the TLDs at the same calibration depth of water and the solid phantom to measure the absorbed dose and verify the accuracy of the theoretical calculation results. The experimental results showed that the dose conversion factors from TLD measurements and the calculation values from the BEAMnrc were in good agreement with a difference within 0.5%. Ten radiotherapy centers were instructed to deliver to the TLDs on central beam axis absorbed dose of 2 Gy. The measured doses were compared with the planned ones. A total of 21 beams were checked. The dose verification differences under reference conditions for 60Co, high energy X-rays of 6, 10 and 15 MV were truly within 4% and that proved the feasibility of applying the method suggested in this work in radiotherapy dose verification

  8. Determination of Absorbed Dose in Large 60-Co Fields Radiotherapy

    Radiation in radiotherapy has selective impact on ill and healthy tissue. During the therapy the healthy tissue receives certain amount of dose. Therefore dose calculations in outer radiotherapy must be accurate because too high doses produce damage in healthy tissue and too low doses cannot ensure efficient treatment of cancer cells. A requirement on accuracy in the dose calculations has lead to improvement of detectors, and development of absolute and relative dosimetry. Determination of the dose distribution with use of computer is based on data provided by the relative dosimetry. This paper compares the percentage depth doses in cubic water phantoms of various dimensions with percentage depth doses calculated with use of Mayneord factor from the experimental depth doses measured in water phantom of large dimension. Depth doses in water phantoms were calculated by the model of empirical dosimetrical functions. The calculations were based on the assumption that large 60Co photon field exceeds the phantom's limits. The experimental basis for dose calculations by the model of empirical dosimetrical functions were exposure doses measured in air and dose reduction factors because of finite phantom dimensions. Calculations were performed by fortran 90 software. It was found that the deviation of dosimetric model was small in comparison to the experimental data. (author)

  9. Absorbed Dose Distribution in a Pulse Radiolysis Optical Cell

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    When a liquid solution in an optical cell is irradiated by an intense pulsed electron beam, it may be important in the chemical analysis of the solution to know the distribution of energy deposited throughout the cell. For the present work, absorbed dose distributions were measured by thin...... radiochromic dye film dosimeters placed at various depths in a quartz glass pulse radiolysis cell. The cell was irradiated with 30 ns pulses from a field-emission electron accelerator having a broad spectrum with a maximum energy of ≈MeV. The measured three-dimensional dose distributions showed sharp gradients...

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

    have arisen from various causes such as the intrinsic dose deviation in the MC calculation, modeling accuracy, and CT-to-density table used in each planning system It is useful to perform independent absorbed-dose calculations with the MC algorithm in intensity-modulated radiation therapy commissioning

  11. Dynamic dose-shaping by gravity-oriented absorbers for total lymph node irradiation

    Rotational therapy with gravity-oriented absorbers is proposed for better total lymph node irradiation (TLI). Two metal semicylinders are joined coaxially (face to face) to form a radiation absorber that is centrally suspended in the beam. During rotation this absorber is kept parallel to itself by gravity, like the riders of a Ferris wheel. The vertebrae remain continuously protected under the absorber's shadow. The circular full-dose region, achieved by ordinary rotation, is now transformed into a horse-shoe region embracing the spine anteriorly. The abdominal lymph nodes are thus irradiated while the spine and most of the normal tissue around the spine are protected. A similar technique is applied for the selective irradiation of the pelvic lymph nodes, which are confined in the two legs of an inverted V region

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

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

  13. Success of the postoperative 131I therapy in young Belarusian patients with differentiated thyroid cancer after Chernobyl depends on the radiation absorbed dose to the blood and the thyroglobulin level

    Differentiated thyroid carcinoma (DTC) in children and young adults is rare but often aggressive and in an advanced stage at diagnosis. In a cohort of young Belarusian patients with advanced DTC after Chernobyl we retrospectively studied parameters influencing the success of the postoperative 131I therapy. Included in the study were 136 patients (83 female, 53 male; median age 14.3 years, range 9.4-22.8 years) who had had total thyroidectomy in Belarus and subsequent 131I therapy and follow-up in Germany. Of the 136 patients, 34 were classified as M1 and 102 as M0 (N0 1, N1 101). The median weight-adjusted 131I activity administered after thyroid hormone withdrawal was 52 MBq/kg (range 24-74 MBq/kg). TNM stage, gender, administered activity, whole-body residence time and blood dose during ablation, Tg and TSH levels, date, and age at time of treatment were tested for their effect on the rate of complete remission (CR). CR was defined as a negative scan and a stimulated Tg level of 0.3). The regression model was able to correctly predict CR in 82 of 102 patients (80.4%). In children and young adults with advanced DTC, the rate of CR after postoperative 131I therapy is dependent on the preablative Tg level and the radiation absorbed dose to the blood. Though the present results must be confirmed in a prospective study, they imply that preablative dosimetry may improve rates of CR. (orig.)

  14. The Norwegian system for implementing the IAEA code of practice based on absorbed dose to water

    The Norwegian Radiation Protection Authority (NRPA) SSDL recommended in 2000 the use of absorbed dose to water as the quality for calibration and code of practice in radiotherapy. The absorbed dose to water standard traceable to BIPM was established in Norway in 1995. The international code of practice, IAEA TRS 398 was under preparation. As a part of the implementation of the new dosimetry system the SSDL went to radiotherapy departments in Norway in 2001. The aim of the visit was to: Prepare and support the users in the implementation of TRS 398 by teaching, discussions and measurements on-site; Gain experience for NRPA in the practical implementation of TRS 398 and perform comparisons between TRS 277 and TRS 398 for different beam qualities; Report experience from implementation of TRS 398 to IAEA. The NRPA 30x30x30 cm3 water phantom is equal to the BIPM calibration phantom. This was used for the photon measurements in 16 different beams. NRPA used three chambers: NE 2571, NE 2611 and PR06C for the photon measurements. As a quality control the set-up was compared with the Finnish site-visit equipment at University Hospital of Helsinki, and the measured absorbed dose to water agreed within 0.6%. The Finnish SSDL calibrated the Norwegian chambers and the absorbed dose to water calibration factors given by the two SSDLs for the three chambers agreed within 0.3%. The local clinical dosimetry in Norway was based on TRS 277. For the site-visit the absorbed dose to water was determined by NRPA using own equipment including the three chambers and the hospitals reference chamber. The hospital determined the dose the same evening using their local equipment. For the 16 photon beams the deviations between the two absorbed dose to water determinations for TRS 277 were in the range -1,7% to +4.0%. The uncertainty in the measurements was 1% (k=1). The deviation was explained in local implementation of TRS 277, the use of plastic phantoms, no resent calibration of thermometers

  15. The 1997 determination of the Australian standards of exposure and absorbed dose at 60Co

    The arrangements for the maintenance of the Australian standards for 60Co 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 90Sr reference sources are reported. Accurate ratios between the Australian Radiation Laboratory (ARL) and Australian Nuclear Science and Technology (ANSTO) 90Sr reference sources are derived for use in future calibrations. The value of 28.8 years for the half-life of 90Sr is confirmed. The usefulness of 90Sr 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 those of the Bureau International

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

    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

  17. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters. The calibration service uses 60Co gamma radiation, ten high energy photon beam qualities between TPR20,10 = 0.639 and 0.802 and ten electron beam qualities between R50 = 1.75 g/cm2 and 8.54 g/cm2. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter used to calibrate several METAS NE 2611A and NE 2571A type ionization chamber working standards in terms of absorbed dose to water in the energy range of 60Co to TPR20,10 = 0.802. The users' reference dosimeters are compared with the working standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co radiation and 1.4% for higher energies (coverage factor k = 2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the IAEA Technical Reports Series No. 398 (TRS 398) code of practice and from Recommendations No. 4 of the Swiss Society of Radiobiology and Medical Physics (SSRMP). The comparisons showed a maximum difference of 1.2% for the NE 2561A and NE 2571A chambers. At 60Co gamma radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau international des poids et mesures.The standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of known particle energy and beam charge is totally absorbed in Fricke solution. The experiment was carried out in the energy range of 5.3 MeV to 22.4 MeV, which allows the determination of the response of the Fricke dosimeter. Finally, the users' dosimeters are compared with the METAS working standards. The overall uncertainty in

  18. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    Full text: The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters using 60Co γ radiation, ten X-ray beam qualities between TPR20,10=0.639 and 0.802 and ten electron beam qualities between R50=1.75 gcm-2 and 8.54 gcm-2. A 22 MeV microtron accelerator with a conventional treatment head is used as radiation source for the high energy photon and electron beams. The treatment head produces clinical beams. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter of the Domen type, that is used to calibrate several METAS transfer standards of type NE2611A and NE2571A in terms of absorbed dose to water in the energy range from 60Co to TPR20,10 = 0.802. User reference dosimeters are compared with the transfer standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co γ radiation and 1.4% for higher energies (coverage factor k=2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the Code of Practice of the International Atomic Energy Agency using the calculated kQ factors listed in table 14. The comparison showed a maximum difference of 0.8% for the NE25611A and NE 2571A chambers. At 60Co γ radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau International des Poids et Mesures BIPM (Sevres) as well as of the National Research Council NRC (Canada). In either case the standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of precisely known particle energy and beam charge is totally absorbed in Fricke solution (ferrous ammonium sulphate) of a given mass. This

  19. Measurement of absorbed doses in a homogeneous β rays fields with an extrapolation chamber

    The main characteristics of a variable cavity ionization chamber are described. Using the ionization current of the detector irradiated in homogeneous β rays fields, the tissue absorbed dose is determined. The corrective factors required to compute this quantity are analysed. Finally, international recommandations (ISO standards) relating to β rays reference fields are given, with the characteristics of β sources required for the energy response study of radiation protection instruments

  20. Preliminary results from a polymer gel dosimeter for absorbed dose imaging in radiotherapy

    Mariani, M. [Dipartimento di Ingegneria Nucleare, Politecnico di Milano, Via Ponzio 34/3, 20133 Milan (Italy); Vanossi, E. [Dipartimento di Ingegneria Nucleare, Politecnico di Milano, Via Ponzio 34/3, 20133 Milan (Italy); INFN-Istituto Nazionale di Fisica Nucleare, Via Celoria 16, 20133 Milan (Italy); Gambarini, G. [INFN-Istituto Nazionale di Fisica Nucleare, Via Celoria 16, 20133 Milan (Italy) and Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milan (Italy)]. E-mail: grazia.gambarini@mi.infn.it; Carrara, M. [Unita di Fisica Sanitaria, Istituto Nazionale dei Tumori, Via Venezian 1, 20133 Milan (Italy); Valente, M. [INFN-Istituto Nazionale di Fisica Nucleare, Via Celoria 16, 20133 Milan (Italy); Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milan (Italy)

    2007-08-15

    The reliability for radiotherapy applications of a normoxic-polymer gel dosimeter, analysed by means of optical methods, was studied. The optical transmittance was measured with a spectrophotometer and imaged with a CCD camera. The characteristics of sensitivity, spatial resolution, image stability, linearity of the response and reproducibility were investigated and analysed. Radiation induces a radical polymerisation in the gel matrix and the resulting macromolecules remain fixed in space making therefore possible the absorbed dose imaging.

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

    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. PMID:11537297

  2. Calculation of absorbed dose of anchorage-dependent cells from internal beta-rays irradiation

    Objective: To elicit the formula of internal dosimetry in anchorage-dependent cells by beta-emitting radionuclides from uniformly distributed volume sources. Methods: By means of the definition of absorbed dose and the MIRD (Medical International Radiation Dose) scheme the formula of internal dosimetry was reasonably deduced. Firstly, studying the systems of suspension culture cells. Then, taking account of the speciality of the systems of the anchorage-dependent cells and the directions of irradiation, the absorbed dose of anchorage -dependent cells was calculated by the accumulated radioactivity, beta-ray energy, and the volume of the cultured systems. Results: The formula of internal dosimetry of suspension culture cells and anchorage-dependent cells were achieved. At the same time, the formula of internal dosimetry of suspension culture cells was compared with that of MIRD and was confirmed accurate. Conclusion: The formula of internal dosimetry is concise, reliable and accurate

  3. Prenatal radiation doses from radiopharmaceuticals

    The radiopharmaceutical administration with diagnostic or therapeutic purpose during pregnancy implies a prenatal radiation dose. The dose assessment and the evaluation of the radiological risks become relevant due to the great radiosensitivity of the fetal tissues in development. This paper is a revision of the available data for estimating fetal doses in the cases of the more frequently used radiopharmaceuticals in nuclear medicine, taking into account recent investigation in placental crossover. The more frequent diagnostic and therapeutic procedures were analyzed according to the radiation doses implied. (author)

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

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

    2016-01-01

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

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

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

  6. Radiation dose during angiographic procedures

    The use of angiographic procedures is becoming more prevalent as new techniques and equipment are developed. There have been concerns in the scientific community about the level of radiation doses received by patients, and indirectly by staff, during some of these radiological procedures. The purpose of this study was to assess the level of radiation dose from angiographic procedures to patient at the Ottawa Hospital, General Campus. Radiation dose measurements, using Thermo-Luminescent Dosimeters (TLDs), were performed on more than 100 patients on various procedures. The results show that while the patient dose from the great majority of angiographic procedures is less than 2 Gy, a significant number of procedures, especially interventional procedures may have doses greater than 2 Gy and may lead to deterministic effects. (author)

  7. Calculation of the field parameter of an absorbing cylindrical radiator in the end face direction

    The problem on determining the field parameters of an absorbing cylindrical radiator for the case, when the detection point is within the end face limits outside the radiation volume, including the presence of plane protection, is solved. The program on calculational integration of the expression obtained is developed. The calculational results on the dose rate isolines position for two nonabsorbing radiators with the relative height of 0.1 and 1 are presented

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

    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...

  9. Influence of elemental weight of human tissues estimated by ICCT software in absorbed dose calculation

    Massicano, Felipe; Possani, Rafael G.; Yoriyaz, Helio [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear; Cintra, Felipe B.; Massicano, Adriana V.F., E-mail: massicano@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (DIRF/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Diretoria de Radiofarmacia

    2011-07-01

    Therapeutic use of radiopharmaceuticals in Nuclear Medicine has been well established and presented good success rates against many forms of cancer. The biologic effects of radionuclide therapy are measured via a physical quantity, the absorbed dose, which is defined as per unit mass of tissue. Therefore, it is of great important an accurate dosimetry to assess the potential effects of treatment and to confirm or contradict the treatment predictions. The most common method used to estimate the absorbed dose at organ level was developed by Medical Internal Radiation Dose (MIRD) Committee, called MIRD system. However, this method does not have adequate patient data to obtain a dose estimate accurate in therapy. In recent years, internal radionuclide radiation dosimetry system evaluated spatial dose distribution. This system is based in Monte Carlo radiation transport codes with anatomical and functional information of the patient. The high accuracy is, at least in part, due to the Monte Carlo method allows human tissues to be characterized by elemental composition and mass density. Thus, a reliable estimation of human tissues (elemental composition and mass density) must be obtained. According to Schneider, Bortfield and Schlegel, the tissue parameters (mass densities ({rho}) and elemental weights ({omega}{sub i})) can be obtained using Hounsfield units provided from Computed Tomography (CT) images. Based on this, the Nuclear Engineer Center of IPEN developed the ICCT software (Image Converter Computed Tomography). It converts CT images in tissue parameters (mass densities ({rho}) and elemental weights ({omega}{sub i}). This work intended to verify if the estimate values by software ICCT of the tissue parameter and elemental weights ({omega}{sub i}) are plausible to estimate the absorbed dose with reasonable accuracy. (author)

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

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

  11. The Effect of Diagnostic Absorbed Doses from 131I on Human Thyrocytes in Vitro

    Zbigniew Adamczewski

    2015-06-01

    Full Text Available Background: Administration of diagnostic activities of 131I, performed in order to detect thyroid remnants after surgery and/or thyroid cancer recurrence/metastases, may lead to reduction of iodine uptake. This phenomenon is called “thyroid stunning”. We estimated radiation absorbed dose-dependent changes in genetic material, in particular in sodium iodide symporter (NIS gene promoter, and NIS protein level in human thyrocytes (HT. Materials and Methods: We used unmodified HT isolated from patients subjected to thyroidectomy exposed to 131I in culture. The different 131I activities applied were calculated to result in absorbed doses of 5, 10, and 20 Gy. Results: According to flow cytometry analysis and comet assay, 131I did not influence the HT viability in culture. Temporary increase of 8-oxo-dG concentration in HT directly after 24 h (p < 0.05 and increase in the number of AP-sites 72 h after termination of exposition to 20 Gy dose (p < 0.0001 were observed. The signs of dose-dependent DNA damage were not associated with essential changes in the NIS expression on mRNA and protein levels. Conclusions: Our observation constitutes a first attempt to evaluate the effect of the absorbed dose of 131I on HT. The results have not confirmed the theory that the “thyroid stunning” reduces the NIS protein synthesis.

  12. Simulation of absorbed dose in human blood with MCNP 4C code

    Biological dosimetry, based on the analysis of solid stained dicentric chromosomes, has been used since the mid 1960s. The intervening years have seen great improvements bringing the technique to a point where dicentric analysis has become a routine component of the radiological protection programs of many countries. Experience of its application in thousands of cases of actual or suspected overexposures has proved the worth of the method. The aberrations scored in the lymphocytes are interpreted in terms of absorbed dose by reference to a dose response calibration curve. This curve will have been produced by exposure of blood in vitro to doses of the appropriate quality of radiation. The doses given to the specimens should be traceable via a physical instrument such as an ionization chamber, to a primary or secondary standard. An alternative to obtain the information about absorbed dose in a specific blood volume is through the Monte Carlo method. The use of such technique is worldwide when physical measurements are inconvenient or impossible, and particularly useful for the solution of complex problems that cannot be modeled by codes that use deterministic methods. It is applied to particle systems as neutrons and electrons, as well as photons or still in mixed systems. Due to difficulties that involve the use of neutrons, this technique has shown extreme importance for preliminary research and experimental arrangements with neutron sources. In this study, the main objective was to simulate the dose absorbed by a blood sample in an experimental arrangement through the irradiation with sources of 241AmBe. It was used the code Monte Carlo N-Particle version 4C (MCNP 4C) whose data had been processed parallel in a computational structure in a cluster. This method allowed estimating the absorbed dose in a specific blood volume, making possible the experimental setup arrangement. (author)

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

    A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water trade mark sign 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 ∼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 trade mark sign 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

  14. Radiation doses to rodents inhabiting a radioactive waste receiving area

    A study was conducted of the gamma ray doses to four species of native rodents inhabiting a low level radioactive liquid waste disposal area. Absorbed doses of radiation were measured with lithium fluoride thermoluminescent dosimeters that were implanted subcutaneously. The absorbed radiation doses and 137Cs body burdens were significantly higher for western harvest mice (Reithrodontomys megalotis) than for deer mice (Peromyscus maniculatus), pinon mice (P. truei) and the least chipmunk (Eutamias minimus), reflecting differences in mobility and habitat preferences of the respective species. The average dose received by harvest mice was 26 mrad/day, which was 26% of the highest gamma dose detected at the ground surface in the study plot, although the maximum dose received by individual mice was as high as 45% of the maximum dose rates in the plot. (author)

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

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

    2014-08-15

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

  16. Basic evaluation of absorbed dose in the 'mantle' field in radiotherapy for Hodgkin's disease

    Hodgkin's disease is one of the radiocurable disease. Avoiding overlap of dose from adjacent fields, megavoltage beams can be utilized at a treatment distance of 100 to 160 cm, making in possible to encompass all of the lymph node chains above the diaphragm in a single treatment field-the 'mantle' field. In the mantle field, we use a set of lead blocks designed individually to spare lager parts of normal lung tissue. We made blocks with beam divergence from low melting lead alloy using lead shot. With these blocks, we measured the absorbed dose in the mantle field in a human phantom, using a thermoluminescent dosimetry system. The results demonstrate that the absorbed dose distribution calculated by the computer system in the axial slices at + 60, 0 and -70 mm from the middle of the radiation field were in good agreements with our dosimetric results in the same slices. An integral dose volume histogram (DVH) obtained from the axial slice in the middle of the radiation field showed quantitatively the irradiated normal lung tissue. In conclusion: first, a dose calculation system using a computer was available in the large irregular shaped field utilizing a long treatment distance such as the 'mantle' field. Second, the DVH may be useful in the quantitative evaluation of lung injury resulting from radiotherapy using the 'mantle' field. (author)

  17. Error in assessing the absorbed dose from the EPR signal from dental enamel

    Dose measurements from EPR signals from dental enamel were analyzed in a random sampling of 100 teeth extracted in liquidators of the Chernobyl accident aftermath and the EPR spectra of dental enamel of 80 intact teeth from children studied. The mean square deviation of enamel sensitivity to ionizing radiation in some teeth is approximately 0.3 of the mean sensitivity value. The variability of the nature EPR spectrum of dental enamel limits in principle the lower threshold of EPR-measured 60 mGy doses. When assessing the individual absorbed doses from the EPR signal from dental enamel without additional exposure it is necessary to bear in mind the extra error of approximately 6-% at a confidence probability P=0.95 caused by the variability of enamel sensitivity to radiation in some teeth. This additional error may be ruled out by graduated additional exposure of the examined enamel samples

  18. Radiation doses - maps and magnitudes

    Three slide sets which can be used in lectures about radiation protection have been published by NRPB. Each consists of 20 slides with captions, and are available at a price of Pound 25 + VAT per set (UK), Pound 25 (Europe) or Pound 35 (rest of world). The slide sets are based on publications in the NRPB ''At-a-Glance'' series of broadsheets, which use illustrations as the main source of information, supported by captions; the series generally avoids the jargon of radiation protection, although each leaflet is based on scientific studies. Slide Set Number 1, ''Radiation Doses - Maps and Magnitudes'' based on the broadsheet of the same name shows visually the main sources of radiation exposure, natural and man-made, with emphasis on the range of doses as well as the averages. The enormous variation in doses across the country is clearly set out. (author)

  19. Radiation biology of low doses

    Present risk assessments and standards in radiation protection are based on the so-called linear no-threshold (LNT) dose - effect hypothesis, i.e., on a linear, proportional relationship between radiation doses and their effects on biological systems. This concept presupposes that any dose, irrespective of its level and time of occurrence, carries the same risk coefficient and, moreover, that no individual biological effects are taken into account. This contribution presents studies of low energy transfer (LET) radiation which deal with the risk of cancer to individual cells. According to the LNT hypothesis, the relationship for the occurrence of these potential effects should be constant over the dose range: successful repair, cell death, mutation with potential carcinogenesis. The results of the studies presented here indicate more differentiated effects as a function of dose application as far as damage to cellular DNA by ionizing radiation is concerned. At the same overall dose level, multiple exposures to low doses sometimes give rise to much smaller effects than those arising from one single exposure to the total dose. These adaptive effects of cells are known from other studies. The results of the study allow the conclusion to be drawn that non-linear relationships must be assumed to exist for the LET radiation considered. Correspondingly, the linear no-threshold hypothesis model should at least be reconsidered with respect to the low dose range in the light of recent biological findings. The inclusion of other topical research findings also could give rise to a new, revised, risk-oriented approach in radiological protection. (orig.)

  20. Energy backscattering of electron beams and absorbed dose in thin layer

    Recent research development in this laboratory concerning radiation effects on the thin layer specimens of organic polymers and p-n junction of semiconductors requires the accurate evaluation of backscattered energy which is especially important for low energy electrons below 1.0 MeV and gives rise to errors of up to some 60 % depending on the materials of backing substrates. The present report describes the past studies on backscattering phenomena on backing substances of various elements and summarizes the experimental results of the measurements of the dose rate absorbed by the thin layer substance on backing substances of various elements as numerical tables which allow convenient determination of dose absorbed by the thin layer specimens on the backing substances. (author)

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

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

  2. Radiation Dose Risk and Diagnostic Benefit in Imaging Investigations

    Dobrescu, Lidia

    2015-01-01

    The paper presents many facets of medical imaging investigations radiological risks. The total volume of prescribed medical investigations proves a serious lack in monitoring and tracking of the cumulative radiation doses in many health services. Modern radiological investigations equipment is continuously reducing the total dose of radiation due to improved technologies, so a decrease in per caput dose can be noticed, but the increasing number of investigations has determined a net increase of the annual collective dose. High doses of radiation are cumulated from Computed Tomography investigations. An integrated system for radiation safety of the patients investigated by radiological imaging methods, based on smart cards and Public Key Infrastructure allow radiation absorbed dose data storage.

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

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

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

    Tavakoli, H.M.B. [Isfahan Univ. of Medical Sciences (Iran, Islamic Republic of)

    2006-07-01

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

  5. Estimation of absorbed doses in humans due to intravenous administration of fluorine-18-fluorodeoxyglucose in PET studies

    Radiation absorbed doses due to intravenous administration of fluorine-18-fluorodeoxyglucose in positron emission tomography (PET) studies were estimated in normal volunteers. The time-activity curves were obtained for seven human organs (brain, heart, kidney, liver, lung, pancreas, and spleen) by using dynamic PET scans and for bladder content by using a single detector. These time-activity curves were used for the calculation of the cumulative activity in these organs. Absorbed doses were calculated by the MIRD method using the absorbed dose per unit of cumulated activity, 'S' value, transformed for the Japanese physique and the organ masses of the Japanese reference man. The bladder wall and the heart were the organs receiving higher doses of 1.2 x 10(-1) and 4.5 x 10(-2) mGy/MBq, respectively. The brain received a dose of 2.9 x 10(-2) mGy/MBq, and other organs received doses between 1.0 x 10(-2) and 3.0 x 10(-2) mGy/MBq. The effective dose equivalent was estimated to be 2.4 x 10(-2) mSv/MBq. These results were comparable to values of absorbed doses reported by other authors on the radiation dosimetry of this radiopharmaceutical

  6. Development of an absorbed dose calorimeter for use in IMRT and small field external beam radiotherapy

    A calorimeter is in development for the absolute measurement of absorbed dose in small fields and complex fields such as those used to deliver intensity modulated radiation therapy. The probe consists of a spherical graphite core surrounded by and separated from a spherical graphite jacket, enclosed in water-equivalent plastic envelope. A spherical geometry was chosen to give approximately isotropic response and sensitivity to dose gradients. Temperature sensing and electrical heating are provided via small thermistors embedded in the graphite, and the temperatures of each component are actively controlled at a set value. Energy absorbed from radiation is measured by substitution, using the electrical heaters. The basic measurement is one of absorbed dose rate rather than absorbed dose. The device is calibrated in terms of absorbed dose to water under standard reference conditions and corrections to its response, in smaller and irregular non-reference fields, are calculated using EGSnrc Monte Carlo and Comsol MultiPhysics to perform finite element analysis of the heat transfer equation. Linearity of the heat equation plays a critical role in analysing measurement uncertainty and the limits on calorimeter performance. In measurements on the central axis of a small field, volume averaging effects make the correction for beam non-uniformity become dominant when the field size is comparable to the core diameter which, in the initial prototype, is 5 mm. The jacket diameter is 7 mm. Absorbed dose in the target volume of an IMRT treatment is measured as a time integral of dose rate, summed over the component fields in a multi-field plan, or integrated over the whole arc in an arc therapy treatment. Although the IMRT planned dose is uniform over the target volume, the instantaneous dose rate (i.e. the dose within a component field, or the dose rate during the arc delivery) is spatially non-uniform. Such variations in dose rate drive heat transfers within the calorimeter

  7. Dose conversion factors for external photon radiation

    Dose conversion factors for radionuclides have been computed and tabulated for two situations: photon doses resulting from immersion in contaminated air, and exposure to a contaminated land surface. Computed dose conversion factors relates absorbed dose rate in human tissue to activity concentration. Tabulated dose conversion factors includes contributions from naturally occurring radionuclides as well as manmade radionuclides: activation products, fission products, actinides. (Auth.)

  8. Dose conversion factors for external photon radiation

    Dose conversion factors for radionuclides have been computed and tabulated for two situations: photon doses resulting from immersion in contaminated air, and exposure to a contaminated land surface. Computed dose conversion factors relates absorbed dose rate in human tissue to activity concentration. Tabulated dose conversion factors includes contributions from naturally occuring radionuclides as well as manmade radionuclides: activation products, fission products, actinides. (author)

  9. Atmospheric radiation flight dose rates

    Tobiska, W. K.

    2015-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has been conducting space weather observations of the atmospheric radiation environment at aviation altitudes that will eventually be transitioned into air traffic management operations. The Automated Radiation Measurements for Aerospace Safety (ARMAS) system and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) both are providing dose rate measurements. Both activities are under the ARMAS goal of providing the "weather" of the radiation environment to improve aircraft crew and passenger safety. Over 5-dozen ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. Flight altitudes now exceed 60,000 ft. and extend above commercial aviation altitudes into the stratosphere. In this presentation we describe recent ARMAS and USEWX results.

  10. Mammography and radiation dose

    The physical aspects of mammography have been investigated by a commissioned group of physicists at six centers in the United States. Continuous monitoring of the various centers has established sound reproducible data. The 1976 evaluation of 63 systems used in 29 screening centers indicated an average dose to the skin of 2.2 rads per exposure. With high resolution mammography in 2000 asymptomatic women over 35 years of age in a screening program at Emory University, 19 cancers were demonstrated; only one was palpable after localization by mammography, the only one with an axillary lymph node metastasis. Each study required an average of less than 1.5 rads to the fibroglandular tissue of the breasts. Mammography is most useful in the 35 to 50 year age group but should not be denied to younger symptomatic or asymptomatic women