Pulsed radiobiology with laser-driven plasma accelerators

Science.gov (United States)

Giulietti, Antonio; Grazia Andreassi, Maria; Greco, Carlo

2011-05-01

Recently, a high efficiency regime of acceleration in laser plasmas has been discovered, allowing table top equipment to deliver doses of interest for radiotherapy with electron bunches of suitable kinetic energy. In view of an R&D program aimed to the realization of an innovative class of accelerators for medical uses, a radiobiological validation is needed. At the present time, the biological effects of electron bunches from the laser-driven electron accelerator are largely unknown. In radiobiology and radiotherapy, it is known that the early spatial distribution of energy deposition following ionizing radiation interactions with DNA molecule is crucial for the prediction of damages at cellular or tissue levels and during the clinical responses to this irradiation. The purpose of the present study is to evaluate the radio-biological effects obtained with electron bunches from a laser-driven electron accelerator compared with bunches coming from a IORT-dedicated medical Radio-frequency based linac's on human cells by the cytokinesis block micronucleus assay (CBMN). To this purpose a multidisciplinary team including radiotherapists, biologists, medical physicists, laser and plasma physicists is working at CNR Campus and University of Pisa. Dose on samples is delivered alternatively by the "laser-linac" operating at ILIL lab of Istituto Nazionale di Ottica and an RF-linac operating for IORT at Pisa S. Chiara Hospital. Experimental data are analyzed on the basis of suitable radiobiological models as well as with numerical simulation based on Monte Carlo codes. Possible collective effects are also considered in the case of ultrashort, ultradense bunches of ionizing radiation.

New challenges in high-energy particle radiobiology

Science.gov (United States)

2014-01-01

Densely ionizing radiation has always been a main topic in radiobiology. In fact, α-particles and neutrons are sources of radiation exposure for the general population and workers in nuclear power plants. More recently, high-energy protons and heavy ions attracted a large interest for two applications: hadrontherapy in oncology and space radiation protection in manned space missions. For many years, studies concentrated on measurements of the relative biological effectiveness (RBE) of the energetic particles for different end points, especially cell killing (for radiotherapy) and carcinogenesis (for late effects). Although more recently, it has been shown that densely ionizing radiation elicits signalling pathways quite distinct from those involved in the cell and tissue response to photons. The response of the microenvironment to charged particles is therefore under scrutiny, and both the damage in the target and non-target tissues are relevant. The role of individual susceptibility in therapy and risk is obviously a major topic in radiation research in general, and for ion radiobiology as well. Particle radiobiology is therefore now entering into a new phase, where beyond RBE, the tissue response is considered. These results may open new applications for both cancer therapy and protection in deep space. PMID:24198199

Experimental radiotherapy and clinical radiobiology. Vol. 8, special issue 1. Proceedings

International Nuclear Information System (INIS)

Doerr, W.; Baumann, M.; Herrmann, T.

1999-01-01

The publication contains the abstracts of all papers and posters presented at the symposium. The headings were as follows: Radiobiology of the lung, mediation of radiation damage in the lung, clinical studies, future clinical directions, as well as documentation and management. (MG)

Radiobiology at GANIL: local project and others fields studied

International Nuclear Information System (INIS)

Anon.

2001-01-01

This article reviews the research that is led in the field of radiobiology using heavy ions at Ganil. Our first studies with heavy ions were mainly focused on chromosome rearrangements induced in irradiated human cells. We analyzed R-banded chromosome rearrangements in human lymphocytes irradiated with several ions having a wide range of linear energy transfer (LET). Damage increased with the fluence and LET but at the higher LET, damage decreased for fluences above 10 7 particles/cm 2 . Chromosome rearrangements of high complexity involve several breaks. DNA strand breaks are concentrated in localized areas and their complexity is greatly increased by high-LET radiations. Our study was mainly qualitative and we showed a clear shift and dispersion of comet distribution towards high tail moments when particle LET and fluence increased. The higher the LET, the greater the level of DNA breaks observed for the same fluence. Gamma rays were more effective in producing DNA breaks than all the ions, at least in the lower dose range. In addition to early damage, high-LET irradiation also induces delayed lesions, and genomic instability occurs after many generations in the progeny of irradiated cells. We observed delayed chromosome instability on human dermis fibroblasts exposed to heavy ions, neon, argon, and lead but not after gamma rays. Various fields of radiobiology are now explored by different research groups. One of the studies aims to detect locally multiple damage sites (LMDS) formed in DNA after exposure to heavy ions. (A.C.)

Basic Radiobiology. Chapter 2

Energy Technology Data Exchange (ETDEWEB)

Dale, R. G. [Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London (United Kingdom); Wondergem, J. [Division of Human Health, International Atomic Energy Agency, Vienna (Austria)

2014-12-15

Radiobiology is the study (both qualitative and quantitative) of the actions of ionizing radiations on living matter. Since radiation has the ability to cause changes in cells which may later cause them to become malignant, or bring about other detrimental functional changes in irradiated tissues and organs, consideration of the associated radiobiology is important in all diagnostic applications of radiation. Additionally, since radiation can lead directly to cell death, consideration of the radiobiological aspects of cell killing is essential in all types of radiation therapy.

Checking the foundation: recent radiobiology and the linear no-threshold theory.

Science.gov (United States)

Ulsh, Brant A

2010-12-01

The linear no-threshold (LNT) theory has been adopted as the foundation of radiation protection standards and risk estimation for several decades. The "microdosimetric argument" has been offered in support of the LNT theory. This argument postulates that energy is deposited in critical cellular targets by radiation in a linear fashion across all doses down to zero, and that this in turn implies a linear relationship between dose and biological effect across all doses. This paper examines whether the microdosimetric argument holds at the lowest levels of biological organization following low dose, low dose-rate exposures to ionizing radiation. The assumptions of the microdosimetric argument are evaluated in light of recent radiobiological studies on radiation damage in biological molecules and cellular and tissue level responses to radiation damage. There is strong evidence that radiation initially deposits energy in biological molecules (e.g., DNA) in a linear fashion, and that this energy deposition results in various forms of prompt DNA damage that may be produced in a pattern that is distinct from endogenous (e.g., oxidative) damage. However, a large and rapidly growing body of radiobiological evidence indicates that cell and tissue level responses to this damage, particularly at low doses and/or dose-rates, are nonlinear and may exhibit thresholds. To the extent that responses observed at lower levels of biological organization in vitro are predictive of carcinogenesis observed in vivo, this evidence directly contradicts the assumptions upon which the microdosimetric argument is based.

On the valency state of radiogenic lead in zircon and its consequences

DEFF Research Database (Denmark)

Kramers, J.; Frei, Robert; Newville, M.

2009-01-01

nucleus comes to rest. Further, a zircon grain, being small, should remain highly oxidizing in its interior by the constant loss of ß-particles, maintaining the 4+ state of radiogenic Pb. From its effective ion radius, similar to that of Zr4+, and its charge, Pb4+ has to be compatible in the zircon...... not resemble that of PbO2. The arguments why radiogenic Pb should be tetravalent are based on analogies with studies relating to the tetravalent state of 234Th and the hexavalent state of 234U, which show that a-recoil in silicates generates a strongly oxidizing environment at the site where the recoiling......-recoil damaged sites could be leached out by any electrolyte solution that reduces it to the divalent state, making it both incompatible and soluble. Thus, discordia can be generated in weathering. The curious observation that discordant Archaean zircon suites generally define trends to lower intercepts at up...

Cancer radiobiology

International Nuclear Information System (INIS)

Almahi, W.A.A.

2006-03-01

The work i have done in this dissertation, was mainly aimed at the literature review of radiotherapy radiobiology discussing the cure of tumours with ionizing radiation, from both the biological and physical point of view. The first chapter an introduction about the radiotherapy and includes: definition, working dose, benefit of radiotherapy, risk of radiotherapy, external and internal radiotherapy and treatment planing. In chapter two the theories of radiobiology and main effects caused by the radiation in the interaction with the biological matter were explained, the damages caused by the use of low and high LET (linear energy transfer) particles to mammalian cells were discussed. And discuss a therapeutic advantage may be gained by one of four hypothetical mechanism: repair the damage of DAN, so when sublethal injury can be repaired if no further hits are sustained. Also the reoxygenation of tumor is important for its effects on stabilization of free radicals produced by ionizing radiation. Hypoxic cells generally require an increased dose of radiation for lethal effect, redistribution, within the cell cycle depends on location of cells and their radiosensitivity also cells undergoing DNA synthesis, the S phase, are much more radioresistant than cells in other phase of the cell cycle, and repopulation of tumor cells is indicator of the surviving cells respond by increased regeneration or repopulation. Repopulation is a greater problem with rapidly proliferating tumors than slower growing neoplasms. These mechanisms are known as the classical four R's of radiation biology. One of the important applications of radiobiology is the radiotherapy and cancer treatment, experimental and theoretical studies in radiation biology contribute to the development of radiotherapy, in this dissertation we discussed the dose response relation so as the size of the tumor increases, and the dose needed for local control like wise increases, the risk of injury to normal tissue

Radiobiological Research in JINR

CERN Document Server

Krasavin, E A

2000-01-01

The results of long-term radiobiological and radiation-genetical research in DRRR (Division of Radiobiology) are summarized. The different radiation-induced effects in bacteria, yeasts, mammalian and human cells after irradiation by gamma-rays and heavy charged particles are considered. The important role of DNA repair processes in biological effectiveness of different types of radiation were shown. The data on mutagenic action of such kinds of radiation on pro- and eukaryotic cells were analyzed. On the basis of our data the hypersensitivity of human and mammalian chromosomes after low doses of gamma-rays (10-20 sGy) was revealed. The radiobiological effect of ^{211}At - methylene blue complex on human melanoma cells was studied. The extremely high effectiveness of this complex on melanoma cells was shown.

Radiation Protection Research: Radiobiology

International Nuclear Information System (INIS)

Desaintes, C.

2000-01-01

The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality in nuclear workers in Belgium; to document the feasibility of retrospective cohort studies in Belgium; (2) to participate in the IARC study; (3) to elucidate the molecular basis of the effects of ionising radiation in the mammalian embryo during the early phases of its development; (4) to assess the genetic risk of maternal exposure to ionizing radiation; (5) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 1999 are reported

Radiation Protection Research: Radiobiology

Energy Technology Data Exchange (ETDEWEB)

Desaintes, C

2000-07-01

The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality in nuclear workers in Belgium; to document the feasibility of retrospective cohort studies in Belgium; (2) to participate in the IARC study; (3) to elucidate the molecular basis of the effects of ionising radiation in the mammalian embryo during the early phases of its development; (4) to assess the genetic risk of maternal exposure to ionizing radiation; (5) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 1999 are reported.

Radiotherapy treatment planning linear-quadratic radiobiology

CERN Document Server

Chapman, J Donald

2015-01-01

Understand Quantitative Radiobiology from a Radiation Biophysics PerspectiveIn the field of radiobiology, the linear-quadratic (LQ) equation has become the standard for defining radiation-induced cell killing. Radiotherapy Treatment Planning: Linear-Quadratic Radiobiology describes tumor cell inactivation from a radiation physics perspective and offers appropriate LQ parameters for modeling tumor and normal tissue responses.Explore the Latest Cell Killing Numbers for Defining Iso-Effective Cancer TreatmentsThe book compil

Influence of oxygen on the chemical stage of radiobiological mechanism

International Nuclear Information System (INIS)

Barilla, Jiří; Lokajíček, Miloš V.; Pisaková, Hana; Simr, Pavel

2016-01-01

The simulation of the chemical stage of radiobiological mechanism may be very helpful in studying the radiobiological effect of ionizing radiation when the water radical clusters formed by the densely ionizing ends of primary or secondary charged particle may form DSBs damaging DNA molecules in living cells. It is possible to study not only the efficiency of individual radicals but also the influence of other species or radiomodifiers (mainly oxygen) being present in water medium during irradiation. The mathematical model based on Continuous Petri nets (proposed by us recently) will be described. It makes it possible to analyze two main processes running at the same time: chemical radical reactions and the diffusion of radical clusters formed during energy transfer. One may study the time change of radical concentrations due to the chemical reactions running during diffusion process. Some orientation results concerning the efficiency of individual radicals in DSB formation (in the case of Co60 radiation) will be presented; the influence of oxygen present in water medium during irradiation will be shown, too. - Highlights: • Creation of the mathematical model. • Realization of the model with the help of Continuous Petri nets. • Obtain the time dependence of changes in the concentration of radicals. • Influence of oxygen on the chemical stage of radiobiological mechanism.

Leaching of uranium and thorium from monazite: III. Leaching of radiogenic daughters

International Nuclear Information System (INIS)

Olander, D.; Eyal, Y.

1990-01-01

The solid-state diffusion model of actinide leaching developed in Part II of this series is applied to leaching of radiogenic daughters of the actinide decay chains. For an untreated natural monazite, the direct leaching component of 228 Th release is larger than that for 232 Th because of enhanced solid-state mobility for 228 Th provided by 228 Ra-recoil tracks. A significant portion of the 228 Th which appears in the leachate, however, is attributed to decay of insoluble 228 Ra which is continually released from the mineral by matrix dissolution and recoil ejection. For a monazite sample that was annealed at 800 degree C prior to leaching, the bulk of the 228 Th in solution was supplied by decay of 228 Ra rejected from the mineral matrix during annealing. The radiogenic 234 U daughter of the 238 U decay chain did not exhibit similarly enhanced leaching because the long half-life of 234 U permitted local radiation damage to be annealed out at ambient temperature prior to 234 U decay

Radiogenic stenosis of the colon following hypernephroma irradiation

International Nuclear Information System (INIS)

Razzaghipour, A.I.

1973-01-01

Refering to extensive home and foreign literature and to the number of 200 patients who were treated during the last 12 years, this paper reports about the radiogenic damage of the colon after irradiating renal tumors. Although no side dispositions of these types of radiation damage were mentioned in the literature, it was noticed in the group of the patients asked as well as in an Anglo-Saxon publication that both after conventional and after cobalt treatment exclusively the upper descending colon resp. the left half of the transverse colon showed alterations in the sense of a stenosing radiation colitis. The possible causes like differing topography of the colon as well as an individual disposition for increased radiation sensibility are discussed. The results of the clinical examination and the radiological symptoms colon stenosis in the number of the patients examined are shown casuistically, the successful surgical treatment of the colon stenosis is put briefly. This should help to contradict the reservations against a combined therapy for renal tumors and make the prognoses of malignant growth more pleasant. (orig.) [de

A radiobiological review on melatonin. A novel radioprotector

International Nuclear Information System (INIS)

Shirazi Hosseinidokht, A.

2007-01-01

Complete text of publication follows. For the sake of improvement in radiation therapy, radiobiology plays a crucial role through explaining observed phenomena, and suggesting improvements to existing therapies. Due to the damaging effects of ionizing radiation, radiobiologists have long been interested in identifying novel, nontoxic, effective, and convenient compounds to protect humans against radiation induced normal tissue injuries. Melatonin (N-acetyl-5-methoxytryptamine), the chief secretory product of the pineal gland in the brain, has been documented to ameliorate the oxidative injuries due to ionizing radiation. This article reviews different features that make melatonin a potentially useful radioprotector. Moreover, based on radiobiological models we hypothesize that melatonin may postpone the saturation of repair enzymes which leads to repairing more induced damage by repair system and more importantly allows the use of higher doses of radiation during radiotherapy to get a better therapeutic ratio. The implications of the accumulated observations suggest by virtue of melatonin's radioprotective and anticancer effects; it is time to use it as a radioprotector both for radiation workers and patients suffering from cancer either alone for cancer inhibition or in combination with traditional radiotherapy for getting a favorable efficacy/toxicity ratio during the treatment. Although compelling evidence suggests that melatonin may be effective for a variety of disorders, the optimum dose of melatonin for human radioprotection is yet to be determined by further research. We propose that, in the future melatonin improve therapeutic ratio in radiation oncology.

Quantitative clinical radiobiology

International Nuclear Information System (INIS)

Bentzen, S.M.

1993-01-01

Based on a series of recent papers, a status is given of our current ability to quantify the radiobiology of human tumors and normal tissues. Progress has been made in the methods of analysis. This includes the introduction of 'direct' (maximum likelihood) analysis, incorporation of latent-time in the analyses, and statistical approaches to allow for the many factors of importance in predicting tumor-control probability of normal-tissue complications. Quantitative clinical radiobiology of normal tissues is reviewed with emphasis on fractionation sensitivity, repair kinetics, regeneration, latency, and the steepness of dose-response curves. In addition, combined modality treatment, functional endpoints, and the search for a correlation between the occurrence of different endpoints in the same individual are discussed. For tumors, quantitative analyses of fractionation sensitivity, repair kinetics, reoxygenation, and regeneration are reviewed. Other factors influencing local control are: Tumor volume, histopathologic differentiation and hemoglobin concentration. Also, the steepness of the dose-response curve for tumors is discussed. Radiobiological strategies for improving radiotherapy are discussed with emphasis on non-standard fractionation and individualization of treatment schedules. (orig.)

Radiobiology and Epidemiology

International Nuclear Information System (INIS)

Desaintes, C; Holmstock, L.

2001-01-01

The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality in nuclear workers in Belgium and to co-ordinate the Belgian contribution to the 'International Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry'; (2) to elucidate the molecular basis of individual susceptibility to ionizing radiation in mammalian embryo during the early phases of its development; (3) to assess the genetic risk of maternal exposure to ionizing radiation; (4) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (5) to monitor the early variations of gene expression induced by ionising radiation and cytokines; (6) to evaluate the use of cytokines and natural substances for improving radiotherapy protocols; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 2000 are reported

Radiobiology and Epidemiology

Energy Technology Data Exchange (ETDEWEB)

Desaintes, C; Holmstock, L

2001-04-01

The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality in nuclear workers in Belgium and to co-ordinate the Belgian contribution to the 'International Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry'; (2) to elucidate the molecular basis of individual susceptibility to ionizing radiation in mammalian embryo during the early phases of its development; (3) to assess the genetic risk of maternal exposure to ionizing radiation; (4) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (5) to monitor the early variations of gene expression induced by ionising radiation and cytokines; (6) to evaluate the use of cytokines and natural substances for improving radiotherapy protocols; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 2000 are reported.

Radiogenic breast cancer risk and mammography

International Nuclear Information System (INIS)

Jayaprakash, Shobha; Nair, C.P.R.; Rao, B.S.; Sawant, S.G.

2001-01-01

There is a general concern that the risks from mammography screening in inducting radiogenic breast cancer may outweigh the possible benefits to be derived from it. A review of epidemiological, case-control and cohort studies of radiogenic breast cancer, age-specific incidence and dose and dose-rate relationship reveals that such a fear is unfounded. The dose to the breast tissues in a quality assured mammography screening programme falls far below the levels that were observed to produce increased relative risk. The age-specific incidence rates also indicate that the need for mammography is for the women of age at which the relative risk is minimum

Radiobiological Optimization in Lung Stereotactic Body Radiation Therapy: Are We Ready to Apply Radiobiological Models?

Directory of Open Access Journals (Sweden)

Marco D’Andrea

2018-01-01

Full Text Available Lung tumors are often associated with a poor prognosis although different schedules and treatment modalities have been extensively tested in the clinical practice. The complexity of this disease and the use of combined therapeutic approaches have been investigated and the use of high dose-rates is emerging as effective strategy. Technological improvements of clinical linear accelerators allow combining high dose-rate and a more conformal dose delivery with accurate imaging modalities pre- and during therapy. This paper aims at reporting the state of the art and future direction in the use of radiobiological models and radiobiological-based optimizations in the clinical practice for the treatment of lung cancer. To address this issue, a search was carried out on PubMed database to identify potential papers reporting tumor control probability and normal tissue complication probability for lung tumors. Full articles were retrieved when the abstract was considered relevant, and only papers published in English language were considered. The bibliographies of retrieved papers were also searched and relevant articles included. At the state of the art, dose–response relationships have been reported in literature for local tumor control and survival in stage III non-small cell lung cancer. Due to the lack of published radiobiological models for SBRT, several authors used dose constraints and models derived for conventional fractionation schemes. Recently, several radiobiological models and parameters for SBRT have been published and could be used in prospective trials although external validations are recommended to improve the robustness of model predictive capability. Moreover, radiobiological-based functions have been used within treatment planning systems for plan optimization but the advantages of using this strategy in the clinical practice are still under discussion. Future research should be directed toward combined regimens, in order to

New evidence for the etiology of the so-called radiation caries. Proof for direct radiogenic damage of the dento-enamel junction

International Nuclear Information System (INIS)

Groetz, K.A.; Wagner, W.; Duschner, H.; Kutzner, J.; Thelen, M.

1997-01-01

Methods: A systematic study is presented, comparing teeth with a manifest radiation caries (group 1, about 60 Gy, long interval to the extraction) and clinically caries free teeth (group 2, about 30 Gy, short interval) with tooth specimens after an experimental enoral (in situ) irradiation (60 Gy, group 3) and after in vitro irradiation (500 to 2.500 Gy, group 4). 60 Co was the irradiation source. Sound teeth were used as a standard (group 5). For non destructive visualisation of subsurface histotomograms by confocal laser scanning microscopy (CLSM) teeth were either used as fresh sections or as Technovit embedded thin slices (sawing grinding technique). Results: Tooth samples from radiotherapy patients (cancer therapeutic doses, long interval before extraction; group 1) showed three characteristic changes: 1. Rarefication of the branching (ramification) of odontoblast processes near the junction, 2. dentine tubules end infront of the interface to the hard tissue and 3. in dentine the interface is characterised by a zone (about 10 μm wide) of low intensity of the remitted light. Conclusions: The obliteration of the dentine tubules, preceded by a degeneration of the odontoblast processes, is obviously the result of a direct radiogenic cell damage with hampered vascularisation and metabolism particularly in the area of the terminations of the odontoblast processes. The deficit in metabolism combined with a latent damage of the parenchyma (hypo-remitting zone) is evidence for the functional symptoms (subsurface caries). The prerequisite for the micromorphological manifestation of this direct irradiation damage is a vital tooth and in consequence cannot be simulated in situ or in vivo. (orig./MG) [de

Paradigms of modern radio-biology

International Nuclear Information System (INIS)

Grodzins'kij, D.M.

2005-01-01

The basic paradigms of modern radio-biology are considered as models of pictures of essence of radio-biology problems and methods of their decision. It is marked on absolute heuristics of these ascending conceptual assertions and their assistance to subsequent development of experimental science. That has the concrete display in the decision of actual tasks of protection of people from action of ionizing radiation

Thyroid cancer. Reevaluation of an experimental model for radiogenic endocrine carcinogenesis

International Nuclear Information System (INIS)

Clifton, K.H.

1984-11-01

The status of experimental studies of radiogenic thyroid cancer is appraised, and some older data are reinterpreted in the light of more recent findings. Problems of thyroid dosimetry, particularly the dosimetry of internal radioiodides, are discussed. The steps in radiation carcinogenesis during the acute phase, the latent phase, and the phase of tumor growth are discussed in terms of thyroid epithelial cell population changes. The roles of three cell populations (undamaged or completely repaired epithelial cells, oncogenically initiated cells, and terminally damaged but functionally competent cells) in neoplasia are described. Finally, the implications for man of these experimental results and conclusions are discussed. 89 refs., 4 figs

Improvement of the projection models for radiogenic cancer risk

International Nuclear Information System (INIS)

Tong Jian

2005-01-01

Calculations of radiogenic cancer risk are based on the risk projection models for specific cancer sites. Improvement has been made for the parameters used in the previous models including introductions of mortality and morbidity risk coefficients, and age-/ gender-specific risk coefficients. These coefficients have been applied to calculate the radiogenic cancer risks for specific organs and radionuclides under different exposure scenarios. (authors)

Experimental radiotherapy and clinical radiobiology. Vol. 20. Proceedings

International Nuclear Information System (INIS)

Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemannn, Hans-Peter; Zips, Daniel

2011-01-01

The proceedings include contributions on the following issues: laser driven proton accelerators on the way for radiotherapy, radiobiological evaluation of new radiations; molecular factors of radiation response; biological targeting; EGFR epidermal growth factor receptor/targeting - combined internal and external irradiation, radiobiology of normal tissues; dose-volume histograms for the radiotherapy: curves without radiobiological relevance or important information for the therapy planning; HPV (human papilloma virus) and radiation sensitivity of HNSCC (head and neck squamous cell carcinomas): evidence, radiobiological mechanism, clinical consequences and perspectives; mechanisms of action and intertumoral heterogeneity of response to EGFR inhibition in radiotherapy of solid tumors; evaluation of biomarkers for radiotherapy.

Some applications of radiation chemistry to biochemistry and radiobiology

International Nuclear Information System (INIS)

Wardman, P.

1987-01-01

In this chapter illustrate the use of radiation chemistry as a tool in investigating biologically important radical reactions, and also outline some studies of models for radiobiological damage. Because aqueous solutions usually offer the most important matrix, an appreciation of the main features of water radiolysis will be essential. Most of the illustrations involve pulse radiolysis, and some familiarity with chemical kinetics is assumed. In addition to these and other chapters in this book, readers find the proceedings of a recent NATO Advanced Study Institute most useful. The authors shall not try to review here all the applications of radiation chemistry to biochemistry and biology, but they will illustrate, using selected examples, the main principles and practical advantages and problems. Another recent volume covers the main contributions of flash photolysis and pulse radiolysis to the chemistry of biology and medicine, complementing earlier reviews. Papers from symposia on radical processes in radiobiology and carcinogenesis, and on super-oxide dismutases, and proceedings of recent international congresses of radiation research, together with the other publications referred to above will enable the reader to gain a comprehensive overview of the role of radicals in biological processes and the contributions of radiation chemistry

Radiobiological experiments at the Munich ion microbeam SNAKE

Energy Technology Data Exchange (ETDEWEB)

Friedl, A.A.; Drexler, G.A.; Loewe, R. [Strahlenbiologisches Inst., Ludwig-Maximilians-Univ. Muenchen (Germany); Dollinger, G.; Hauptner, A.; Hable, V.; Greubel, C.; Kruecken, R. [Physik Dept. E12, Technische Univ. Muenchen, Garching (Germany); Cremer, T.; Dietzel, S. [Dept. Biologie II, Ludwig-Maximilians-Univ. Muenchen, Planegg-Martinsried (Germany)

2005-07-01

The ion microbeam SNAKE at the Munich 14 MV tandem accelerator was recently adapted for irradiation of cells and is now routinely used for radiobiological experiments. Several features, including ion-optical beam focussing to achieve a targeting accuracy of about 500 nm, fast movement of the beam by electrostatic deflection and single ion preparation make SNAKE an excellent tool for localized irradiation with a defined number of ions. The ion spectrum available ranges from 20 MeV protons to 200 MeV gold ions, thus allowing to vary the LET over four orders of magnitude and to conduct low and high LET irradiation in a single experimental set-up. This offers the possibility of a systematic analysis of the cellular response mechanisms in their dependence on dose and LET. Other current lines of research include analysis of the spatio-temporal dynamics of protein recruitment at damaged chromatin sites and determination of the mobility of damaged chromatin regions in the interphase nucleus. (orig.)

A competing risk model for reduction in life expectancy from radiogenic cancer

International Nuclear Information System (INIS)

Davis, H.T.

1978-01-01

Latent radiogenic cancer fatalities from reactor accidents are considered to be more important than early fatalities. However, early fatalities generally result in appreciable life shortening for the affected individual whereas latent cancer fatalities generally result in limited life shortening. In this report a mathematical model is developed to express the reduction in life expectancy from radiogenic cancer as a function of dose received. The model is then used to compare the linear model of latent radiogenic cancer incidence with several nonlinear models that have appeared in the literature. (author)

Biophysical models of radiobiological effects

International Nuclear Information System (INIS)

Obaturov, G.M.

1987-01-01

Radiobiological effect models at different organization levels, developed by the author, are presented. Classification and analysis of concepts and biophysical models at molecular, genetic and cellular levels, developed by Soviet and foreign authors in comparison to inherent models, are conducted from the viewpoint of system approach to radiobiological processes and of modelling principles. Models are compared with each other, limits of their applicability and drawbacks are determined. Evaluation of the model truthfulness is conducted according to a number of criteria, ways of further investigations and experimental examination of some models are proposed

A radiobiological review on melatonin. A novel radioprotector

International Nuclear Information System (INIS)

Shirazi, A.; Ghobadi, G.; Ghazi-Khansari, M.

2007-01-01

In spite of the fact that radiotherapy is a common and effective tool for cancer treatment; the radio sensitivity of normal tissues adjacent to the tumor which are unavoidably exposed to radiation limits therapeutic gain. For the sake of improvement in radiation therapy, radiobiology- the study of the action of ionizing radiation on living things- plays a crucial role through explaining observed phenomena, and suggesting improvements to existing therapies. Due to the damaging effects of ionizing radiation, radiobiologists have long been interested in identifying novel, nontoxic, effective, and convenient compounds to protect humans against radiation induced normal tissue injuries. In hundreds of investigations, melatonin (N-acetyl-5-methoxytryptamine), the chief secretory product of the pineal gland in the brain, has been documented to ameliorate the oxidative injuries due to ionizing radiation. This article reviews different features that make melatonin a potentially useful radioprotector. Moreover, based on radiobiological models we can hypothesize that melatonin may postpone the saturation of repair enzymes which leads to repairing more induced damage by repair system and more importantly allows the use of higher doses of radiation during radiotherapy to get a better therapeutic ratio. The implications of the accumulated observations suggest by virtue of melatonin's radioprotective and anticancer effects; it is time to use it as a radioprotector both for radiation workers and patients suffering from cancer either alone for cancer inhibition or in combination with traditional radiotherapy for getting a favorable efficacy/toxicity ratio during the treatment. Although compelling evidence suggests that melatonin may be effective for a variety of disorders, the optimum dose of melatonin for human radioprotection is yet to be determined. We propose that, in the future, melatonin improve the therapeutic ratio in radiation oncology. (author)

Radiogenic health effects: communicating risks to the general public

International Nuclear Information System (INIS)

Strzelczyk, Jadwiga

1999-01-01

Harmful effects of prolonged radiation exposures were recognized early on following the discovery of X-rays by W.C. Roentgen in 1895. The type and severity of radiogenic effects are functions of a number of factors, radiation quality and quantity, chemical toxicity, and radiosensitivity of irradiated tissues being the most significant ones. Currently, there are several human registries for radiogenic cancers. Atomic bomb and nuclear test survivors, and populations exposed to medical irradiation constitute the largest study cohorts. Two general types of radiogenic effects have emerged from these registries: prompt and delayed. While the effects of acute exposures are very well documented, investigations of the effects of low-level exposures require the use of mathematical models. Communicating the risks of lower-level chronic radiation exposures to the general public remains a challenging task. The most effective approaches include clear interpretation and placing radiation risks in perspective: risks versus benefits, and comparisons with risks carried by common activities in which we all engage. (author)

Introduction to radiobiology of targeted radionuclide therapy

Directory of Open Access Journals (Sweden)

Jean-Pierre ePOUGET

2015-03-01

Full Text Available During the last decades, new radionuclide-based targeted therapies have emerged as efficient tools for cancer treatment. Targeted radionuclide therapies (TRT are based on a multidisciplinary approach that involves the cooperation of specialists in several research fields. Among them, radiobiologists investigate the biological effects of ionizing radiation, specifically the molecular and cellular mechanisms involved in the radiation response. Most of the knowledge about radiation effects concerns external beam radiation therapy (EBRT and radiobiology has then strongly contributed to the development of this therapeutic approach. Similarly, radiobiology and dosimetry are also assumed to be ways for improving TRT, in particular in the therapy of solid tumors which are radioresistant. However, extrapolation of EBRT radiobiology to TRT is not straightforward. Indeed, the specific physical characteristics of TRT (heterogeneous and mixed irradiation, protracted exposure and low absorbed dose rate differ from those of conventional EBRT (homogeneous irradiation, short exposure and high absorbed dose rate, and consequently the response of irradiated tissues might be different. Therefore, specific TRT radiobiology needs to be explored. Determining dose-effect correlation is also a prerequisite for rigorous preclinical radiobiology studies because dosimetry provides the necessary referential to all TRT situations. It is required too for developing patient-tailored TRT in the clinic in order to estimate the best dose for tumor control, while protecting the healthy tissues, thereby improving therapeutic efficacy. Finally, it will allow to determine the relative contribution of targeted effects (assumed to be dose-related and non-targeted effects (assumed to be non-dose-related of ionizing radiation. However, conversely to EBRT where it is routinely used, dosimetry is still challenging in TRT. Therefore, it constitutes with radiobiology, one of the main

Endogenous opiates mediate radiogenic behavioral change

International Nuclear Information System (INIS)

Mickley, G.A.; Stevens, K.E.; White, G.A.; Gibbs, G.L.

1983-01-01

Exposure of C57BL/6J mice to ionizing radiation caused stereotypical locomotor hyperactivity similar to that produced by morphine. Naloxone administration prevented this radiation-induced behavioral activation. These results support the hypothesis that endorphins are involved in some aspects of radiogenic behavioral change

Radiobiological basis of SBRT and SRS.

Science.gov (United States)

Song, Chang W; Kim, Mi-Sook; Cho, L Chinsoo; Dusenbery, Kathryn; Sperduto, Paul W

2014-08-01

Stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) have been demonstrated to be highly effective for a variety of tumors. However, the radiobiological principles of SBRT and SRS have not yet been clearly defined. It is well known that newly formed tumor blood vessels are fragile and extremely sensitive to ionizing radiation. Various lines of evidence indicate that irradiation of tumors with high dose per fraction, i.e. >10 Gy per fraction, not only kills tumor cells but also causes significant damage in tumor vasculatures. Such vascular damage and ensuing deterioration of the intratumor environment then cause ischemic or indirect/secondary tumor cell death within a few days after radiation exposure, indicating that vascular damage plays an important role in the response of tumors to SBRT and SRS. Indications are that the extensive tumor cell death due to the direct effect of radiation on tumor cells and the secondary effect through vascular damage may lead to massive release of tumor-associated antigens and various pro-inflammatory cytokines, thereby triggering an anti-tumor immune response. However, the precise role of immune assault on tumor cells in SBRT and SRS has not yet been clearly defined. The "4 Rs" for conventional fractionated radiotherapy do not include indirect cell death and thus 4 Rs cannot account for the effective tumor control by SBRT and SRS. The linear-quadratic model is for cell death caused by DNA breaks and thus the usefulness of this model for ablative high-dose SBRT and SRS is limited.

METHODOLOGICAL PROBLEMS OF PRACTICAL RADIOGENIC RISK ESTIMATIONS

Directory of Open Access Journals (Sweden)

A. Т. Gubin

2014-01-01

Full Text Available Mathematical ratios were established according to the description of the calculation procedure for the values of the nominal risk coefficient given in the ICRP Recommendations 2007. It is shown that the lifetime radiogenic risk is a linear functional from the distribution of the dose in time with a multiplier descending with age. As a consequence, application of the nominal risk coefficient in the risk calculations is justified in the case when prolonged exposure is practically evenly distributed in time, and gives a significant deviation at a single exposure. When using the additive model of radiogenic risk proposed in the UNSCEAR Report 2006 for solid cancers, this factor is almost linearly decreasing with the age, which is convenient for its practical application.

Epidemiology of radiogenic breast cancer

International Nuclear Information System (INIS)

Howe, G.R.

1984-01-01

The primary objective of epidemiologic studies of radiogenic breast cancer is to use empirical data from human populations exposed to radiation, in order to delineate increases in risk of breast cancer as a function of the radiation characteristics and the characteristics of the women exposed. In addition, such empirical data may be used to test hypotheses concerning the biological mechanism of radiation-induced breast cancer, and this mechanism in turn may serve as a useful model both for other radiogenic solid tumors, and for breast tumors induced by other carcinogens. Specifically, the objective may be formulated in terms of developing an appropriate relatively simple mathematical model, whose functional form may be tested and whose parameters may be estimated from the relevant human data. It is necessary to derive such a model, both because of the sampling instability of estimates based on small subgroups of populations and also because observations may not be available in populations with the characteristics of interest. These latter two restrictions are exemplified by the problem of estimating an increase in risk for individuals with relatively small exposures, and the problem of estimating lifetime risk

Melanomas: radiobiology and role of radiation therapy

International Nuclear Information System (INIS)

Peschel, Richard E.

1995-01-01

Purpose/Objective: This course will review the radiobiology of malignant melanoma (MM) and the clinical use of radiation therapy for metastatic melanoma and selected primary sites. The course will emphasize the scientific principles underlying the clinical treatment of MM. Introduction: The incidence of malignant melanoma has one of the fastest growth rates in the world. In 1991, there were 32,000 cases and 7,000 deaths from MM in the United States. By the year 2000, one of every 90 Americans will develop MM. Wide local excision is the treatment of choice for Stage I-II cutaneous MM. Five-year survival rates depend on (a) sex: female-63%, male-40%; (b) tumor thickness: t 4 mm-25%; (c) location: extremity-60%, trunk-41%; and (d) regional lymph node status: negative-77%, positive-31%. Despite adequate surgery, 45-50% of all MM patients will develop metastatic disease. Radiobiology: Both the multi-target model: S = 1-(1-e-D/Do)n and the linear quadratic mode: -In(S) = alpha x D + beta x D2 predict a possible benefit for high dose per fraction (> 400 cGy) radiation therapy for some MM cell lines. The extrapolation number (n) varies from 1-100 for MM compared to other mammalian cells with n=2-4. The alpha/beta ratios for a variety of MM cell lines vary from 1 to 33. Other radiobiologic factors (repair of potentially lethal damage, hypoxia, reoxygenation, and repopulation) predict a wide variety of clinical responses to different time-dose prescriptions including high dose per fraction (> 400 cGy), low dose per fraction (200-300 cGy), or b.i.d. therapy. Based on a review of the radiobiology of MM, no single therapeutic strategy emerges which could be expected to be successful for all tumors. Time-Dose Prescriptions: A review of the retrospective and prospective clinical trials evaluating various time-dose prescriptions for MM reveals: (1) MM is a radiosensitive tumor over a wide range of diverse time-dose prescriptions; and (2) The high clinical response rates to a

Primordial Pb, radiogenic Pb and lunar soil maturity

International Nuclear Information System (INIS)

Reed, G.W. Jr.; Jovanovic, S.

1978-01-01

The soil maturity index I/sub s//FeO does not apply to either 204 Pb/sub r/ or C/sub hyd/; both are directly correlated with the submicron Fe 0 (I/sub s/) content. They act as an index of soil maturity which is independent of soil composition. In contrast to primordial Pb, radiogenic Pb is lost during soil maturation. Radiogenic Pb is present in mineral grains and may be lost by solar wind sputtering (or volatilization) and not resupplied. 204 Pb coating grain surfaces acts as a reservoir to provide the 204 Pb being extracted in the Fe 0 formation process. Venting or some other volatile source may replenish the surface 204 Pb. 1 figure

Status and role of radiobiology in veterinary medicine

International Nuclear Information System (INIS)

Benova, K.

2013-01-01

In this presentation history of radiobiology in University of Veterinary Medicine and Pharmacy in Kosice from 1949 is presented. Scientific and pedagogic programs, role of veterinary physician as well as concept of radiobiology and cooperation are reviewed. Changes in Poecilia reticulata and Artemia franciscana after gamma radiation are presented.

Radiogenic Lead Isotopes and Time Stratigraphy in the Hudson River, New York

International Nuclear Information System (INIS)

Chillrud, Steven N.; Bopp, Richard F.; Ross, James M.; Chaky, Damon A.; Hemming, Sidney; Shuster, Edward L.; Simpson, H. James; Estabrooks, Frank

2004-01-01

Radionuclide, radiogenic lead isotope and trace metal analyses on fine-grained sediment cores collected along 160 km of the upper and tidal Hudson River were used to examine temporal trends of contaminant loadings and to develop radiogenic lead isotopes both as a stratigraphic tool and as tracers for resolving decadal particle transport fluxes. Very large inputs of Cd, Sb, Pb, and Cr are evident in the sediment record, potentially from a single manufacturing facility. The total range in radiogenic lead isotope ratios observed in well-dated cores collected about 24 km downstream of the plant is large (e.g., maximum difference in 206 Pb/ 207 Pb is 10%), characterized by four major shifts occurring in the 1950s, 1960s, 1970s and 1980s. The upper Hudson signals in Cd and radiogenic lead isotopes were still evident in sediments collected 160 km downstream in the tidal Hudson. The large magnitude and abrupt shifts in radiogenic lead isotope ratios as a function of depth provide sensitive temporal constraints that complement information derived from radionuclide analyses to significantly improve the precision of dating assignments. Application of a simple dilution model to data from paired cores suggests much larger sediment inputs in one section of the river than previously reported, suggesting particle influxes to the Hudson have been underestimated

Radiobiology software for educational purpose

International Nuclear Information System (INIS)

Pandey, A.K.; Sharma, S.K.; Kumar, R.; Bal, C.S.; Nair, O.; Haresh, K.P.; Julka, P.K.

2014-01-01

To understand radio-nuclide therapy and the basis of radiation protection, it is essential to understand radiobiology. With limited time for classroom teaching and limited time and resources for radiobiology experiments students do not acquire firm grasp of theoretical mathematical models and experimental knowledge of target theory and Linear quadratic models that explain nature of cell survival curves. We believe that this issue might be addressed with numerical simulation of cell survival curves using mathematical models. Existing classroom teaching can be reoriented to understand the subject using the concept of modeling, simulation and virtual experiments. After completion of the lecture, students can practice with simulation tool at their convenient time. In this study we have developed software that can help the students to acquire firm grasp of theoretical and experimental radiobiology. The software was developed using FreeMat ver 4.0, open source software. Target theory, linear quadratic model, cell killing based on Poisson model have been included. The implementation of the program structure was to display the menu for the user choice to be made and then program flows depending on the users choice. The program executes by typing 'Radiobiology' on the command line interface. Students can investigate the effect of radiation dose on cell, interactively. They can practice to draw the cell survival curve based on the input and output data and they can also compare their handmade graphs with automatically generated graphs by the program. This software is in the early stage of development and will evolve on user feedback. We feel this simulation software will be quite useful for students entering in the nuclear medicine, radiology and radiotherapy disciplines. (author)

Toward a national consensus: teaching radiobiology to radiation oncology residents

International Nuclear Information System (INIS)

Zeman, Elaine M.; Dynlacht, Joseph R.; Rosenstein, Barry S.; Dewhirst, Mark W.

2002-01-01

Purpose: The ASTRO Joint Working Group on Radiobiology Teaching, a committee composed of members having affiliations with several national radiation oncology and biology-related societies and organizations, commissioned a survey designed to address issues of manpower, curriculum standardization, and instructor feedback as they relate to resident training in radiation biology. Methods and Materials: Radiation biology instructors at U.S. radiation oncology training programs were identified and asked to respond to a comprehensive electronic questionnaire dealing with instructor educational background, radiation biology course content, and sources of feedback with respect to curriculum planning and resident performance on standardized radiation biology examinations. Results: Eighty-five radiation biology instructors were identified, representing 73 radiation oncology residency training programs. A total of 52 analyzable responses to the questionnaire were received, corresponding to a response rate of 61.2%. Conclusion: There is a decreasing supply of instructors qualified to teach classic, and to some extent, clinical, radiobiology to radiation oncology residents. Additionally, those instructors with classic training in radiobiology are less likely to be comfortable teaching cancer molecular biology or other topics in cancer biology. Thus, a gap exists in teaching the whole complement of cancer and radiobiology curricula, particularly in those programs in which the sole responsibility for teaching falls to one faculty member (50% of training programs are in this category). On average, the percentage of total teaching time devoted to classic radiobiology (50%), clinical radiobiology (30%), and molecular and cancer biology (20%) is appropriate, relative to the current makeup of the board examination. Nevertheless large variability exists between training programs with respect to the total number of contact hours per complete radiobiology course (ranging from

National Radiobiology Archives distributed access programmer's guide

International Nuclear Information System (INIS)

Prather, J.C.; Smith, S.K.; Watson, C.R.

1991-12-01

The National Radiobiology Archives is a comprehensive effort to gather, organize, and catalog original data, representative specimens, and supporting materials related to significant radiobiology studies. This provides researchers with information for analyses which compare or combine results of these and other studies and with materials for analysis by advanced molecular biology techniques. This Programmer's Guide document describes the database access software, NRADEMO, and the subset loading script NRADEMO/MAINT/MAINTAIN, which comprise the National Laboratory Archives Distributed Access Package. The guide is intended for use by an experienced database management specialist. It contains information about the physical and logical organization of the software and data files. It also contains printouts of all the scripts and associated batch processing files. It is part of a suite of documents published by the National Radiobiology Archives

Morphological differences in the response of mouse small intestine to radiobiologically equivalent doses of X and neutron irradiation

International Nuclear Information System (INIS)

Carr, K.E.; Hamlet, R.; Nias, A.H.; Watt, C.

1984-01-01

A scale has been developed to describe the effects of radiation on small intestinal villi. The scale has been used to compare the damage done to the villi in the period 0-5 days after irradiation by X-irradiation or neutron irradiation, using 10 Gy X-rays and 5 Gy neutrons, doses which are radiobiologically equivalent when assessed by the microcolony assay method. Use of the scale indicates that the damage done to the villi by neutrons is greater than that produced by X-rays. This has implications for the interpretation of radiobiological equivalent doses (R.B.E.). Resin light microscopy and transmission electron microscopy (T.E.M.) have also been used to examine small intestinal damage after 10 Gy X-irradiation and 5 Gy neutron irradiation. Differences include variations in crypt shape, mitotic activity and the proportion of crypts which are heavily parasitised. As well as the differences in villous shape which have been reflected in the different values on the scoring system, there are also variations in the response of the constituent cells of the epithelial compartment of the villi. In general, the effect of the neutron irradiation is more severe than that of the X-rays, particularly as would be suggested by a simple quantitation of crypt regeneration

Research in Radiobiology

International Nuclear Information System (INIS)

Miller, S.C.; Buster, D.S.

1988-01-01

This document contains the tables of contents for the reports published by the University of Utah Radiobiology Laboratory from 1953--1987. Also included is a keyword index for the reports, and references for all books, book and symposia chapters and journal article published by Laboratory staff between 1950 and 1988

3D slicing of radiogenic heat production in Bahariya Formation, Tut oil field, North-Western Desert, Egypt.

Science.gov (United States)

Al-Alfy, I M; Nabih, M A

2013-03-01

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 μWm(-3) to 2.2 μWm(-3). Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 μWm(-3) is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Radiobiological Effects of Alpha-Particles from Astatine-211: From DNA Damage to Cell Death

Energy Technology Data Exchange (ETDEWEB)

Claesson, Kristina

2011-05-15

In recent years, the use of high linear energy transfer (LET) radiation for radiotherapeutic applications has gained increased interest. Astatine-211 (211At) is an alpha-particle emitting radionuclide, promising for targeted radioimmunotherapy of isolated tumor cells and microscopic clusters. To improve development of safe radiotherapy using 211At it is important to increase our knowledge of the radiobiological effects in cells. During radiotherapy, both tumors and adjacent normal tissue will be irradiated and therefore, it is of importance to understand differences in the radio response between proliferating and resting cells. The aim of this thesis was to investigate effects in fibroblasts with different proliferation status after irradiation with alpha-particles from 211At or X-rays, from inflicted DNA damage, to cellular responses and biological consequences. Throughout this work, irradiation was performed with alpha-particles from 211A or X-rays. The induction and repair of double-strand breaks (DSBs) in human normal fibroblasts were investigated using pulsed-field gel electrophoresis and fragment analysis. The relative biological effectiveness (RBE) of 211At for DSB induction varied between 1.4 and 3.1. A small increase of DSBs was observed in cycling cells compared to stationary cells. The repair kinetics was slower after 211At and more residual damage was found after 24 h. Comparison between cells with different proliferation status showed that the repair was inefficient in cycling cells with more residual damage, regardless of radiation quality. Activation of cell cycle arrests was investigated using immunofluorescent labeling of the checkpoint kinase Chk2 and by measuring cell cycle distributions with flow cytometry analysis. After alpha-particle irradiation, the average number of Chk2-foci was larger and the cells had a more affected cell cycle progression for several weeks compared with X-irradiated cells, indicating a more powerful arrest after 211At

Radiobiological studies with marine fish

International Nuclear Information System (INIS)

Pentreath, R.J.

1975-01-01

The experimental methodology employed in radiobiological studies with fish is discussed and reviewed. The problems of care and maintenance of healthy stock fish are cons. (author)idered, including the techniques of egg and larval rearing. A variety of methods have been used to study the accumulation and loss of radionuclides, including labelled water, food and injections, and their relative merits are discussed in conjunction with the parameters affecting these processes. Other, more specialized, techniques that aid the physiological interpretation of tracer experiments are also discussed. Finally, consideration is given to some of the mathematical models that have been applied to radiobiological studies with fish, and of their value in extrapolating laboratory data to environmental conditions

Radiobiological input to radiation protection standards

International Nuclear Information System (INIS)

Bond, V.P.

1981-01-01

A brief review of the radiobiological data relevant to radiation protection standards is given. In particular the nature of the dose-response relationships for mutagenesis and carcinogenesis in animals and man is discussed with reference to the BEIR 1 1972, the NRC75, the UNSCEAR 77 and the NCRP80 Reports. It was concluded that the linear-no-threshold relationship for mutagenesis and carcinogenesis is too simple and that the relationship is best described by curves of varying slopes depending on the dose rate. By examining the data on the incidence of actual tumour systems in animals and man in relation to radiation dose, it was shown that the relationships developed in the simple Tradescantia single-cell system appear to hold widely throughout radiobiology. In developing radiation protection standards, first animal and human radiobiological data were used in determining an appropriate risk coefficient for late and genetic effects for the human being, and second an appropriate comparison of radiation and other more common risks was used as a basis for setting limits of incidence in the exposed population/individual. (U.K.)

Radiation oncology: radiobiological and physiological perspectives

International Nuclear Information System (INIS)

Awwad, H.K.

1990-01-01

This book deals with the normal tissue and tumor radiation-induced responses in terms of the underlying radiobiological and physiological process. Coverage includes the following topics: Functional test for normal tissue responses. Relation to the underlying target cell, Clinical structural end-points, e.g., increased lung density in CT-scan. Conditions and parameters of the LQ-model in clinical applications. An NSD-type of formalism is still clinically applicable. Clinical importance of the kinetics of recovery. The notion of normal tissue tolerance and tumor control. The steepness of the response curve. How accurate radiotherpy should be. The volume effect: clinical, biological and physiological perspectives. The tumor bed effect, residual damage and the problems of reirradiation. Radiation-induced perturbations of the immune response. Clinical consequences. Exploitation to a therapeutic benefit. Hypoxia in human solid tumors. Probing and methods of control. Growth of human tumors. Parameters, measurement and clinical implications. The dose-rate effect. The optimum use of low dose rate irradiation in human cancer

Atmospheric and radiogenic gases in ground waters from the Stripa granite

International Nuclear Information System (INIS)

Andrews, J.N.; Hussain, N.; Youngman, M.J.

1989-01-01

Ground waters from depths of 350 m to 1,250 m in the Stripa granite contain dissolved radiogenic He in amounts up to 50,000 times that due to air-saturation. The groundwater He-contents increase with depth and lie close to the expected profile for He loss by aqueous diffusion (D = 0.032 m 2 a -1 ). Measurements on core samples show that the rock has retained about 10% of the possible cumulative radiogenic He and that this component is lost by matrix diffusion (D = 5 x 10 -7 m 2 a -1 ). Diffusive equilibrium between He in fracture fluids and in the adjacent rock matrix is rapidly established for the narrow fracture widths of the flow system. A major loss of stored He by both diffusion and advection along fluid-filled fractures is attributed to the proximity of a major fraction of uranium to the aqueous flow system because of its deposition within an interconnective microfracture system. The crustal flux of He is limited by its diffusion coefficient in the matrix of a granitic crust but may be supplemented by transport due to fluid circulation. The 3 He/ 4 He ratio of the excess He present in the Stripa ground waters, corresponds to that expected for radiogenic He production within the granite. The 40 Ar/ 36 Ar ratio of dissolved Ar shows that radiogenic 40 Ar has been released from the rock matrix, especially for ground waters from greater than 450 m depth. Slow alteration reactions are the most probable cause of this radiogenic 40 Ar release which has occurred in the more saline ground waters. Groundwater recharge temperatures, estimated from their noble gas contents, are about 3 degree C lower than those for modern shallow ground waters in the locality and are related to the stable isotope composition of the groundwater

Natural radiogenic heat production in the northeastern part of the North German Basin; Natuerliche radiogene Waermeproduktion im Nordostdeutschen Becken

Energy Technology Data Exchange (ETDEWEB)

Ullner, H A [GeoForschungsZentrum Potsdam (Germany)

1997-12-01

The radiogenic heat-production rate is a parameter that affects the thermal structure in the sedimentary cover. The parameter is important to warrant an extensive study. The first results gained in the northeastern part of the North German Basin show values in the range between 2.2 and 2.6 {mu}W/m{sup 3} in Permian mudstones in the Peckensen borehole and in the Bonese borehole (Altmark area). Comparable results were obtained in mudstones from a {gamma}-ray log measured in the Rheinsberg borehole (Brandenburg area). (orig.) [Deutsch] Die Untersuchung der thermischen Struktur des nordostdeutschen Beckens erfordert Kenntnisse ueber die radiogene Waermeproduktion der in zahlreichen Bohrungen aufgeschlossenen Sedimente. Die erste Ergebnisse eines am GFZ Postdam begonnenen Messprogrammes zeigen Waermeproduktionsraten im Bereich 2,2 bis 2,6 {mu}W/m{sup 3} in Tonsteinen des Perm in den Bohrungen Peckensen und Bonese (Altmark). Eine vergleichbare Waermeproduktion wurde anhand eines {gamma}-ray-Logs in Tonsteinen in der Bohrung Rheinsberg (Brandenburg) ermittelt. (orig.)

Heavy-ion radiobiology: new approaches to delineate mechanisms underlying enhanced biological effectiveness

Science.gov (United States)

Blakely, E. A.; Kronenberg, A.; Chatterjee, A. (Principal Investigator)

1998-01-01

Shortly after the discovery of polonium and radium by Marie Curie and her husband and colleague, Pierre Curie, it was learned that exposure to these alpha-particle emitters produced deleterious biological effects. The mechanisms underlying the increased biological effectiveness of densely ionizing radiations, including alpha particles, neutrons and highly energetic heavy charged particles, remain an active area of investigation. In this paper, we review recent advances in several areas of the radiobiology of these densely ionizing radiations, also known as heavy ions. Advances are described in the areas of DNA damage and repair, chromosome aberrations, mutagenesis, neoplastic transformation in vitro, genomic instability, normal tissue radiobiology and carcinogenesis in vivo. We focus on technical innovations, including novel applications of pulsed-field gel electrophoresis, fluorescence in situ hybridization (FISH), linkage analysis, and studies of gene expression and protein expression. We also highlight the use of new cellular and animal systems, including those with defined DNA repair deficiencies, as well as epithelial cell model systems to assess neoplastic transformation both in vitro and in vivo. The studies reviewed herein have had a substantial impact on our understanding of the genotoxic effects of heavy ions as well as their distinct effects on tissue homeostasis. The use of these radiations in cancer therapy is also discussed. The use of both heavy-ion and proton therapy is on the upswing in several centers around the world, due to their unique energy deposition characteristics that enhance the therapeutic effect and help reduce damage to normal tissue.

Progress on clustered DNA damage in radiation research

International Nuclear Information System (INIS)

Yang Li'na; Zhang Hong; Di Cuixia; Zhang Qiuning; Wang Xiaohu

2012-01-01

Clustered DNA damage which caused by high LET heavy ion radiation can lead to mutation, tumorigenesis and apoptosis. Promoting apoptosis of cancer cells is always the basis of cancer treatment. Clustered DNA damage has been the hot topic in radiobiology. The detect method is diversity, but there is not a detail and complete protocol to analyze clustered DNA damage. In order to provide reference for clustered DNA damage in the radiotherapy study, the clustered DNA damage characteristics, the latest progresses on clustered DNA damage and the detecting methods are reviewed and discussed in detail in this paper. (authors)

The effects of radiogenic heat on groundwater flow

International Nuclear Information System (INIS)

Beddoes, R.J.; Tammemagi, H.Y.

1986-03-01

The effects of radiogenic heat released by a nuclear waste repository on the groundwater flow in the neighbouring rock mass is reviewed. The report presents an overview of the hydrogeologic properties of crystalline rocks in the Canadian Shield and also describes the mathematical theory of groundwater flow and heat transfer in both porous media and fractured rock. Numerical methods for the solution of the governing equations are described. A number of case histories are described where analyses of flow systems have been performed both with and without radiogenic heat sources. A number of relevant topics are reviewed such as the role of the porous medium model, boundary conditions and, most importantly, the role of complex coupled processes where the effects of heat and water flow are intertwined with geochemical and mechanical processes. The implications to radioactive waste disposal are discussed

Radiobiological considerations in magna-field irradiation

International Nuclear Information System (INIS)

Evans, R.G.

1983-01-01

Radiobiological considerations are described for total body irradiation (TBI) as given to patients undergoing bone marrow transplantation (BMT). Although much progress has been made in the use of BMT for refractory leukemias, many patients still die from interstitial pneumonia and relapse. Fractionated TBI has been introduced in order to improve leukemic cell kill, while increasing the degree of normal tissue tolerance. Traditionally, bone marrow stem cells, leukemic cells and immunocytes have been considered as having a limited ability to repair radiation damage while cells of lung tissue and intestinal epithelial cells have a greater capacity. During fractionated radiation therapy or continuous low-dose rate exposure, repair of sublethal damage between fractions allows greater recovery in the cells of lung tissue to those in the bone marrow. Clinically, the potential benefit of six fractions over one fraction or low dose-rate TBI has yet to be proved, although there is suggestive evidence for a reduced incidence of interstitial pneumonitis. However, other extraneous factors such as doses to the lung, differences in conditioning regimens, effect of increased delay in BMT for patients receiving fractionated TBI, and the unmeasurable differences between institutions make definite conclusions impossible. Despite this, a consensus for dose fractionation has developed and most centers are moving away from the use of large single dose TBI

3D slicing of radiogenic heat production in Bahariya Formation, Tut oil field, North-Western Desert, Egypt

International Nuclear Information System (INIS)

Al-Alfy, I.M.; Nabih, M.A.

2013-01-01

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 μWm −3 to 2.2 μWm −3 . Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 μWm −3 is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts. - Highlights: ► Radiogenic heat production ranging from 0.21 to 2.25 μWm −3 averaging about 0.95 μWm −3 . ► High Stdev. 0.3 μWm −3 indicates a heterogenic distribution of (RHP) values. ► Statistically, the range from 0.8 to 1.2 μWm −3 is about 45.3 % of the values. ► A renew RHP which can be produced from the study area are calculated as 6.3 kW

New radiobiological, radiation risk and radiation protection paradigms

International Nuclear Information System (INIS)

Goodhead, Dudley T.

2010-01-01

The long-standing conventional paradigm for radiobiology has formed a logical basis for the standard paradigm for radiation risk of cancer and heritable effects and, from these paradigms, has developed the internationally applied system for radiation protection, but with many simplifications, assumptions and generalizations. A variety of additional radiobiological phenomena that do not conform to the standard paradigm for radiobiology may have potential implications for radiation risk and radiation protection. It is suggested, however, that the current state of knowledge is still insufficient for these phenomena, individually or collectively, to be formulated systematically into a new paradigm for radiobiology. Additionally, there is at present lack of direct evidence of their relevance to risk for human health, despite attractive hypotheses as to how they might be involved. Finally, it remains to be shown how incorporation of such phenomena into the paradigm for radiation protection would provide sufficient added value to offset disruption to the present widely applied system. Further research should aim for better mechanistic understanding of processes such as radiation-induced genomic instability (for all radiation types) and bystander effects (particularly for low-fluence high-LET particles) and also priority should be given to confirmation, or negation, of the relevance of the processes to human health risks from radiation.

Dictionary of radiation protection, radiobiology and nuclear medicine

Energy Technology Data Exchange (ETDEWEB)

Sube, R [comp.

1986-01-01

Radiation protection, including aspects of radiobiology, nuclear medicine, and nuclear legislation, has an important role within nuclear research and the use of radioactive materials. Radiation protection comprises all measures and efforts to prevent the unwanted distribution and negative influence of ionizing radiation, especially where the human organism and the living environment are involved. The increasing role of radiation protection is reflected by the foundation of institutes in all industrial countries to control such radiant energy and prevent radiation damage. Nowadays ionizing radiation is employed on a large scale for basic investigations in biochemistry, molecular biology and genetics, in soil tests, fertilization problems and pest control in agriculture, as well as for medicinal diagnoses and therapy. This dictionary is a thematic enlargement of the four-language 'Dictionary of Nuclear Engineering', compiled by the same author. It comprises about 12,000 terms in each language.

Proceedings of the 4th Radiobiological conference with international participation 2008

International Nuclear Information System (INIS)

Benova, K.; Falis, M.

2008-06-01

Scientific conference deals with problems in radiobiology, photobiology and radio-environmental sciences. The Conference included the following sessions: (i): Radiobiology; (ii) Biology. Proceedings contains thirty-two papers dealing with the scope of INIS

Heavy charged particle radiobiology: using enhanced biological effectiveness and improved beam focusing to advance cancer therapy.

Science.gov (United States)

Allen, Christopher; Borak, Thomas B; Tsujii, Hirohiko; Nickoloff, Jac A

2011-06-03

Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. 2011 Elsevier B.V. All rights reserved.

Practical Radiobiology for Proton Therapy Planning

Science.gov (United States)

Jones, Bleddyn

2017-12-01

Practical Radiobiology for Proton Therapy Planning covers the principles, advantages and potential pitfalls that occur in proton therapy, especially its radiobiological modelling applications. This book is intended to educate, inform and to stimulate further research questions. Additionally, it will help proton therapy centres when designing new treatments or when unintended errors or delays occur. The clear descriptions of useful equations for high LET particle beam applications, worked examples of many important clinical situations, and discussion of how proton therapy may be optimized are all important features of the text. This important book blends the relevant physics, biology and medical aspects of this multidisciplinary subject. Part of Series in Physics and Engineering in Medicine and Biology.

Radiogenic lead from poly-metallic thorium ores as a valuable material for advanced nuclear facilities

Energy Technology Data Exchange (ETDEWEB)

Kulikov, Gennady G.; Apse, Vladimir A.; Kulikov, Evgeny G.; Kozhahmet, Bauyrzhan K.; Shkodin, Alexey O.; Shmelev, Anatoly N.

2017-03-15

Main purpose of the study is assessing reasonability for recovery, production and application of radiogenic lead as a coolant, neutron moderator and neutron reflector in advanced fast reactors and accelerator-driven systems (ADS). The following results were obtained: 1. Radiogenic lead with high content of isotope {sup 208}Pb can be extracted from thorium or mixed thorium-uranium ores because {sup 208}Pb is a final product of {sup 232}Th natural decay chain. 2. The use of radiogenic lead with high {sup 208}Pb content in advanced fast reactors and ADS makes it possible to improve significantly their neutron-physical and thermal-hydraulic parameters. 3. The use of radiogenic lead with high {sup 208}Pb content in advanced fast reactors as a coolant opens the possibilities for more intense fuel breeding and for application of well-known oxide fuel instead of the promising but not tested enough nitride fuel under the same safety parameters. 4. The use of radiogenic lead with high {sup 208}Pb content in advanced fast reactors as a neutron reflector opens a possibility for substantial elongation of prompt neutron lifetime. As a result, chain fission reaction in the reactor core could be slowed down, and the reactor operation could become safer. 5. The use of radiogenic lead with high {sup 208}Pb content in ADS as a coolant can upgrade substantially the level of neutron flux in the ADS blanket. Thus, favorable conditions could be formed in the ADS blanket for effective transmutation of radioactive wastes with low cross-sections of radiative neutron capture.

The ATM gene and the radiobiology of ataxia-telangiectasia

International Nuclear Information System (INIS)

Jorgensen, T.J.; Shiloh, Y.

1996-01-01

Ataxia-telangiectasia (A-T) is the classic human genetic disease involving severe ionizing radiation sensitivity and as such has been intensely studied by radiation biologists over the years. Unlike its counterpart for UV light sensitivity -xeroderma pigmentosum - A-T has no obvious DNA repair defect; and there has been much speculation as to the mechanism underlying the altered radioresponses associated with this disease. The gene defective in A-T (ATM) has recently been cloned, and its primary coding sequence determined. The primary sequence of the ATM protein suggests that it has some regulatory functions related to cellular radioresponse and maintenance of genomic stability, and shares these functions with a growing family of other proteins in various organisms. At this juncture it is appropriate to review our current knowledge about the radiobiology of A-T and reflect on the possible radiobiological mechanisms that are suggested by the ATM gene itself. This article will attempt briefly to review current knowledge about the radiobiology of A-T and to introduce new speculations about underlying radiobiological mechanisms that are suggested by the primary amino acid sequence of the predicted ATM gene product. (Author)

Radiobiology in clinical radiation therapy - Part III: Normal tissue damage

International Nuclear Information System (INIS)

Travis, Elizabeth L.

1996-01-01

Objective: This is the third part of a course designed for residents in radiation oncology preparing for their boards. This part of the course will focus on the mechanisms underlying damage in normal tissues. Although conventional wisdom long held that killing and depletion of a critical cell(s) in a tissue was responsible for the later expression of damage, histopathologic changes in normal tissue can now be explained and better understood in terms of the new molecular biology. The concept that depletion of a single cell type is responsible for the observed histopathologic changes in normal tissues has been replaced by the hypothesis that damage results from the interaction of many different cell systems, including epithelial, endothelial, macrophages and fibroblasts, via the production of specific autocrine, paracrine and endocrine growth factors. A portion of this course will discuss the clinical and experimental data on the production and interaction of those cytokines and cell systems considered to be critical to tissue damage. It had long been suggested that interindividual differences in radiation-induced normal tissue damage was genetically regulated, at least in part. Both clinical and experimental data supported this hypothesis but it is the recent advances in human and mouse molecular genetics which have provided the tools to dissect out the genetic component of normal tissue damage. These data will be presented and related to the potential to develop genetic markers to identify sensitive individuals. The impact on clinical outcome of the ability to identify prospectively sensitive patients will be discussed. Clinically it is well-accepted that the volume of tissue irradiated is a critical factor in determining tissue damage. A profusion of mathematical models for estimating dose-volume relationships in a number of organs have been published recently despite the fact that little data are available to support these models. This course will review the

Radioactive and radiogenic isotopes in sediments from Cooper Creek, Western Arnhem Land

Energy Technology Data Exchange (ETDEWEB)

Frostick, A. [Charles Darwin University, Darwin, NT 0909 (Australia); ERISS, GPO Box 461, Darwin, NT 0801 (Australia)], E-mail: alison.frostick@cdu.edu.au; Bollhoefer, A. [ERISS, GPO Box 461, Darwin, NT 0801 (Australia); Parry, D.; Munksgaard, N. [Charles Darwin University, Darwin, NT 0909 (Australia); Evans, K. [ERISS, GPO Box 461, Darwin, NT 0801 (Australia)

2008-03-15

Protection of the environment post-mining is a key objective of rehabilitation, especially where runoff and erosion from rehabilitated mine sites could potentially lead to contamination of the surrounding land and watercourses. As part of an overall assessment of the success of rehabilitation at the former Nabarlek uranium (U) mine, an appraisal of stable lead (Pb) isotopes, radionuclides and trace metals within sediments and soils was conducted to determine the off site impacts from a spatial and temporal perspective. The study found localised areas on and adjacent to the site where soils had elevated levels of trace metals and radionuclides. Lead isotope ratios are highly radiogenic in some samples, indicating the presence of U-rich material. There is some indication that erosion products with more radiogenic Pb isotope ratios have deposited in sediments downstream of the former ore body. However, there is no indication that the radiogenic erosion products found on the mine site at present have significantly contaminated sediments further downstream of Cooper Creek.

Radioactive and radiogenic isotopes in sediments from Cooper Creek, Western Arnhem Land

International Nuclear Information System (INIS)

Frostick, A.; Bollhoefer, A.; Parry, D.; Munksgaard, N.; Evans, K.

2008-01-01

Protection of the environment post-mining is a key objective of rehabilitation, especially where runoff and erosion from rehabilitated mine sites could potentially lead to contamination of the surrounding land and watercourses. As part of an overall assessment of the success of rehabilitation at the former Nabarlek uranium (U) mine, an appraisal of stable lead (Pb) isotopes, radionuclides and trace metals within sediments and soils was conducted to determine the off site impacts from a spatial and temporal perspective. The study found localised areas on and adjacent to the site where soils had elevated levels of trace metals and radionuclides. Lead isotope ratios are highly radiogenic in some samples, indicating the presence of U-rich material. There is some indication that erosion products with more radiogenic Pb isotope ratios have deposited in sediments downstream of the former ore body. However, there is no indication that the radiogenic erosion products found on the mine site at present have significantly contaminated sediments further downstream of Cooper Creek

Radiobiological considerations in the treatment of neuroblastoma by total body irradiation

International Nuclear Information System (INIS)

Wheldon, T.E.; O'Donoghue, J.; Gregor, A.; Livingstone, A.; Wilson, L.; West of Scotland Health Boards, Glasgow

1986-01-01

Neuroblastoma is a radiosensitive neoplasm for which total body irradiation (TBI) is presently under clinical consideration. Collated data on the radiobiology of human neuroblastoma cells in vitro indicates moderate cellular radiosensitivity and low capacity for accumulation of sublethal damage. Mathematical studies incorporating these parameters suggest that low dose fractionated TBI is unlikely to achieve significant levels of tumour cell kill. When high dose TBI is used in conjuction with bone marrow rescue a tumour 'log cell kill' of 4-5 should be achievable. This effect would be additional to that acheived by chemotherapy. Fractionated TBI with bone marrow rescue may be curative for some patients in clinical remission who are presently destined to relapse. (Auth.)

Tcp and NTCP radiobiological models: conventional and hypo fractionated treatments in radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Astudillo V, A.; Paredes G, L. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Resendiz G, G.; Posadas V, A. [Hospital Angeles Lomas, Av. Vialidad de la Barranca s/n, Col. Valle de las Palmas, 52763 Huixquilucan de Degallado, Estado de Mexico (Mexico); Mitsoura, E. [Universidad Autonoma del Estado de Mexico, Facultad de Medicina, Paseo Tollocan, Esq. Jesus Carranza s/n, Col. Moderna de la Cruz, 50180 Toluca, Estado de Mexico (Mexico); Rodriguez L, A.; Flores C, J. M., E-mail: armando.astudillo@inin.gob.mx [Hospital Medica Sur, Puente de Piedra 150, Col. Toriello Guerra, 14050 Tlalpan, Mexico D. F. (Mexico)

2015-10-15

The hypo and conventional fractionated schedules performance were compared in terms of the tumor control and the normal tissue complications. From the records of ten patients, treated for adenocarcinoma and without mastectomy, the dose-volume histogram was used. Using radiobiological models the probabilities for tumor control and normal tissue complications were calculated. For both schedules the tumor control was approximately the same. However, the damage in the normal tissue was larger in conventional fractionated schedule. This is important because patients assistance time to their fractions (15 fractions/25 fractions) can be optimized. Thus, the hypo fractionated schedule has suitable characteristics to be implemented. (Author)

Tcp and NTCP radiobiological models: conventional and hypo fractionated treatments in radiotherapy

International Nuclear Information System (INIS)

Astudillo V, A.; Paredes G, L.; Resendiz G, G.; Posadas V, A.; Mitsoura, E.; Rodriguez L, A.; Flores C, J. M.

2015-10-01

The hypo and conventional fractionated schedules performance were compared in terms of the tumor control and the normal tissue complications. From the records of ten patients, treated for adenocarcinoma and without mastectomy, the dose-volume histogram was used. Using radiobiological models the probabilities for tumor control and normal tissue complications were calculated. For both schedules the tumor control was approximately the same. However, the damage in the normal tissue was larger in conventional fractionated schedule. This is important because patients assistance time to their fractions (15 fractions/25 fractions) can be optimized. Thus, the hypo fractionated schedule has suitable characteristics to be implemented. (Author)

An irradiation facility with a horizontal beam for radiobiological studies

International Nuclear Information System (INIS)

Czub, J.; Banas, D.; Braziewicz, J.; Choinski, J.; Jaskola, M.; Korman, A.; Szeflinski, Z.; Wojcik, A.

2006-01-01

A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw Univ.. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as in the region of the Bragg peak. (authors)

National Radiobiology Archives distributed access programmer's guide

Energy Technology Data Exchange (ETDEWEB)

Prather, J. C. [Linfield Coll., McMinnville, OR (United States); Smith, S. K.; Watson, C. R. [Pacific Northwest Lab., Richland, WA (United States)

1991-12-01

The National Radiobiology Archives is a comprehensive effort to gather, organize, and catalog original data, representative specimens, and supporting materials related to significant radiobiology studies. This provides researchers with information for analyses which compare or combine results of these and other studies and with materials for analysis by advanced molecular biology techniques. This Programmer's Guide document describes the database access software, NRADEMO, and the subset loading script NRADEMO/MAINT/MAINTAIN, which comprise the National Laboratory Archives Distributed Access Package. The guide is intended for use by an experienced database management specialist. It contains information about the physical and logical organization of the software and data files. It also contains printouts of all the scripts and associated batch processing files. It is part of a suite of documents published by the National Radiobiology Archives.

Dictionary of radiation protection, radiobiology and nuclear medicine

International Nuclear Information System (INIS)

Sube, R.

1986-01-01

Radiation protection, including aspects of radiobiology, nuclear medicine, and nuclear legislation, has an important role within nuclear research and the use of radioactive materials. Radiation protection comprises all measures and efforts to prevent the unwanted distribution and negative influence of ionizing radiation, especially where the human organism and the living environment are involved. The increasing role of radiation protection is reflected by the foundation of institutes in all industrial countries to control such radiant energy and prevent radiation damage. Nowadays ionizing radiation is employed on a large scale for basic investigations in biochemistry, molecular biology and genetics, in soil tests, fertilization problems and pest control in agriculture, as well as for medicinal diagnoses and therapy. This dictionary is a thematic enlargement of the four-language 'Dictionary of Nuclear Engineering', compiled by the same author. It comprises about 12,000 terms in each language. (orig.)

Fast neutrons: Inexpensive and reliable tool to investigate high-LET particle radiobiology

International Nuclear Information System (INIS)

Gueulette, J.; Slabbert, J.P.; Bischoff, P.; Denis, J.M.; Wambersie, A.; Jones, D.

2010-01-01

Radiation therapy with carbon ions as well as missions into outer space have boosted the interest for high-LET particle radiobiology. Optimization of treatments in accordance with technical developments, as well as the radioprotection of cosmonauts during long missions require that research in these domains continue. Therefore suitable radiation fields are needed. Fast neutrons and carbon ions exhibit comparable LET values and similar radiobiological properties. Consequently, the findings obtained with each radiation quality could be shared to benefit knowledge in all concerned domains. The p(66+Be) neutron therapy facilities of iThemba LABS (South Africa) and the p(65)+Be neutron facility of Louvain-la-Neuve (Belgium) are in constant use to do radiobiological research for clinical applications with fast neutrons. These beams - which comply with all physical and technical requirements for clinical applications - are now fully reliable, easy to use and frequently accessible for radiobiological investigations. These facilities thus provide unique opportunities to undertake radiobiological experimentation, especially for investigations that require long irradiation times and/or fractionated treatments.

The challenge for the paradigms heat have guided the radiobiology in the past

International Nuclear Information System (INIS)

Real, A.

2001-01-01

Until recently, it has been commonly accepted that the biological consequences following ionizing radiation exposure are attributable to direct DNA damage. However, in the last decade some evidence have emerged to suggest that the classical genetic effects associated with radiation exposure (i.e. mutations, chromosomal aberrations, micronucleus) are not necessarily the result of the direct damage induced in the cellular DNA. These effects have been termed non-targeted and include radiation-induced genomic instability, effects detected after cytoplasmic irradiation and bystander effects. All of them support the hypothesis that important genetic consequences of radiation may arise in cells that in themselves receive no direct radiation exposure at all. The radioinduced damage signals could be transmitted to these cells from those that have been directly irradiated. The non-targeted effects challenge the paradigms that have guided radiobiology in the past and may change our thinking about the early events in the carcinogenic process and in particular about the critical targets for genetic and carcinogenic damage by radiation. These effects could be particularly important at low doses, when non all the cells are directly exposed to an ionizing track. (Author) 45 refs

With the Radiobiology Group

CERN Multimedia

CERN PhotoLab

1980-01-01

The Radiobiology Group carries out experiments to study the effect of radiation on living cells. The photo shows the apparatus for growing broad beans which have been irradiated by 250 GeV protons. The roots are immersed in a tank of running water (CERN Weekly Bulletin 26 January 1981 and Annual Report 1980 p. 160). Karen Panman, Marilena Streit-Bianchi, Roger Paris.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-07-15

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

(RadioBiological Optimization of External-Beam Radiotherapy

Directory of Open Access Journals (Sweden)

Alan E. Nahum

2012-01-01

Full Text Available “Biological optimization” (BIOP means planning treatments using (radiobiological criteria and models, that is, tumour control probability and normal-tissue complication probability. Four different levels of BIOP are identified: Level I is “isotoxic” individualization of prescription dose at fixed fraction number. is varied to keep the NTCP of the organ at risk constant. Significant improvements in local control are expected for non-small-cell lung tumours. Level II involves the determination of an individualized isotoxic combination of and fractionation scheme. This approach is appropriate for “parallel” OARs (lung, parotids. Examples are given using our BioSuite software. Hypofractionated SABR for early-stage NSCLC is effectively Level-II BIOP. Level-III BIOP uses radiobiological functions as part of the inverse planning of IMRT, for example, maximizing TCP whilst not exceeding a given NTCP. This results in non-uniform target doses. The NTCP model parameters (reflecting tissue “architecture” drive the optimizer to emphasize different regions of the DVH, for example, penalising high doses for quasi-serial OARs such as rectum. Level-IV BIOP adds functional imaging information, for example, hypoxia or clonogen location, to Level III; examples are given of our prostate “dose painting” protocol, BioProp. The limitations of and uncertainties inherent in the radiobiological models are emphasized.

Effect of Rosiglitazone on Radiation Damage in Bone Marrow Hemopoiesis

Science.gov (United States)

Benkő, Klára; Pintye, Éva; Szabó, Boglárka; Géresi, Krisztina; Megyeri, Attila; Benkő, Ilona

2008-12-01

To study radiobiological effects and drugs, which can modify radiation injury, has an importance if we would like to avoid harmful effects of radiation due to emergency situations or treat patients with malignant diseases by radiotherapy. During the long treatment schedules patients may be treated by not only anticancer but many other drugs because of accompanying diseases. These drugs may also modify radiobiological effects. Rosiglitazone pre-treatment proved to be myeloprotective and accelerated recovery of 5-fluorouracil-damaged bone marrow in our previous experiments. Our new studies are designed to evaluate whether rosiglitazone has similar beneficial effects in radiation-damaged hemopoiesis. Bone marrow damage was precipitated by total body irradiation (TBI) using single increasing doses (2-10 Gy) of γ—irradiation in groups of mice. Lethality was well correlated with damage in hemopoiesis measured by cellularity of bone marrow (LD50 values were 4.8 and 5.3 gray respectively). Rosiglitazone, an insulin-sensitizing drug, had no significant effect on bone marrow cellularity. Insulin resistance associated with obesity or diabetes mellitus type 2 is intensively growing among cancer patients requiring some kind of radiotherapy. Therefore it is important to know whether drugs used for their therapy can modify radiation effects.

Effect of Rosiglitazone on Radiation Damage in Bone Marrow Hemopoiesis

International Nuclear Information System (INIS)

Benko', Klara; Pintye, Eva; Szabo, Boglarka; Geresi, Krisztina; Megyeri, Attila; Benko, Ilona

2008-01-01

To study radiobiological effects and drugs, which can modify radiation injury, has an importance if we would like to avoid harmful effects of radiation due to emergency situations or treat patients with malignant diseases by radiotherapy. During the long treatment schedules patients may be treated by not only anticancer but many other drugs because of accompanying diseases. These drugs may also modify radiobiological effects. Rosiglitazone pre-treatment proved to be myeloprotective and accelerated recovery of 5-fluorouracil-damaged bone marrow in our previous experiments. Our new studies are designed to evaluate whether rosiglitazone has similar beneficial effects in radiation-damaged hemopoiesis. Bone marrow damage was precipitated by total body irradiation (TBI) using single increasing doses (2-10 Gy) of γ--irradiation in groups of mice. Lethality was well correlated with damage in hemopoiesis measured by cellularity of bone marrow (LD 50 values were 4.8 and 5.3 gray respectively). Rosiglitazone, an insulin-sensitizing drug, had no significant effect on bone marrow cellularity. Insulin resistance associated with obesity or diabetes mellitus type 2 is intensively growing among cancer patients requiring some kind of radiotherapy. Therefore it is important to know whether drugs used for their therapy can modify radiation effects.

Thresholds in radiobiology

International Nuclear Information System (INIS)

Katz, R.; Hofmann, W.

1982-01-01

Interpretations of biological radiation effects frequently use the word 'threshold'. The meaning of this word is explored together with its relationship to the fundamental character of radiation effects and to the question of perception. It is emphasised that although the existence of either a dose or an LET threshold can never be settled by experimental radiobiological investigations, it may be argued on fundamental statistical grounds that for all statistical processes, and especially where the number of observed events is small, the concept of a threshold is logically invalid. (U.K.)

Radiogenic cell transformation and carcinogenesis

Science.gov (United States)

Yang, T. C.; Georgy, K. A.; Mei, M.; Durante, M.; Craise, L. M.

1995-01-01

Radiation carcinogenesis is one of the major biological effects considered important in the risk assessment for space travel. Various biological model systems, including both cultured cells and animals, have been found useful for studying the carcinogenic effects of space radiations, which consist of energetic electrons, protons and heavy ions. The development of techniques for studying neoplastic cell transformation in culture has made it possible to examine the cellular and molecular mechanisms of radiation carcinogenesis. Cultured cell systems are thus complementary to animal models. Many investigators have determined the oncogenic effects of ionizing and nonionizing radiation in cultured mammalian cells. One of the cell systems used most often for radiation transformation studies is mouse embryonic cells (C3H10T1/2), which are easy to culture and give good quantitative dose-response curves. Relative biological effectiveness (RBE) for heavy ions with various energies and linear energy transfer (LET) have been obtained with this cell system. Similar RBE and LET relationship was observed by investigators for other cell systems. In addition to RBE measurements, fundamental questions on repair of sub- and potential oncogenic lesions, direct and indirect effect, primary target and lesion, the importance of cell-cell interaction and the role of oncogenes and tumor suppressor genes in radiogenic carcinogenesis have been studied, and interesting results have been found. Recently several human epithelial cell systems have been developed, and ionizing radiation have been shown to transform these cells. Oncogenic transformation of these cells, however, requires a long expression time and/or multiple radiation exposures. Limited experimental data indicate high-LET heavy ions can be more effective than low-LET radiation in inducing cell transformation. Cytogenetic and molecular analyses can be performed with cloned transformants to provide insights into basic genetic

Cell survivor: Modeling radiobiological phenomena with a new kind of simulation

Science.gov (United States)

Spencer, Melissa A.

Despite widespread societal fear of radiation, whether justified or unjustified, and whether related to medicine (e.g., CT scans) or other forms of nuclear and atomic radiation (e.g., nuclear power) there is a fundamental lack of basic understanding of radiation effects on the human body. Different types of radiation are psychologically grouped into the same general fear category irrespective of their different potential to do harm, and this fear is not balanced by their potential beneficial effects. By modeling certain types of radiation biology experiments within a game engine, it is possible to enhance the player's intuitive understanding of radiobiology, both the effects of different types of radiation as well as different environmental factors that can enhance or suppress repair. For this dissertation, a game/simulation has been developed that intends to narrow the gap between public perception and the reality of these physical processes. The building blocks of this simulation are cells, which are damaged by incident radiation, accumulating either single or double strand breaks. They grow and reproduce, and are especially vulnerable during certain phases of the cell cycle (e.g. mitosis). Two dominant damage mechanisms are modeled, along with multiple repair mechanisms, for example, double strand breaks can be repaired by either non-homologous end joining or homologous repair. The output of the developed simulation was compared to data collected in experimental studies and the simulation appears to be a valid representation of the dominant mechanisms of radiobiology, as far as can be determined within the scope of this dissertation. Cell survival curves generated from playtest data display shoulders that depend on the LET of incident radiation, and rest time restores repair capability. In addition to public outreach, the presented code can be used to aid investigators by collecting data during play that can be used as a distributed Monte Carlo simulation

Workshop on radiobiological effectiveness of neutrons

International Nuclear Information System (INIS)

Stapleton, G.E.; Thomas, R.G.; Thiessen, J.W.

1985-09-01

The radiobiological effectiveness (RBE) of neutrons has become the subject of some heated discussions in both scientific and radiation-protection oriented communities. This has become especially so since the realization that neutron exposures of A-bomb survivors in Hiroshima were considerably lower than previously assumed, thus ''devaluating'' the importance of what we thought was a solid human data base. At the same time, more recent data from radiobiological research appeared to indicate that, at least for some biological endpoints, the RBE of neutrons at low doses and low dose rates was increased dramatically compared to the RBE at higher dose and dose rates. As a consequence, the protection of health against neutrons became a subject of some urgency. The objective of this workshop was to evaluate the existing data base in order to determine the need for additional research in this field. 22 refs., 3 figs., 6 tabs

Radiobiological studies with the nematode Caenorhabditis elegans. Genetic and developmental effects of high LET radiation

International Nuclear Information System (INIS)

Nelson, G.A.; Schubert, W.W.; Marshall, T.M.

1992-01-01

The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long-duration space flights where exposure levels represents a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets. There are many consequences of this feature to biological endpoints when compared with effects of ionizing photons. Dose vs response and dose-rate kinetics may be modified, DNA and cellular repair systems may be altered in their abilities to cope with damage, and the qualitative features of damage may be unique for different ions. The nematode Caenorhabditis elegans is being used to address these and related questions associated with exposure to radiation. HZE-induced mutation, chromosome aberration, cell inactivation and altered organogenesis are discussed along with plans for radiobiological experiments in space. (author)

Recent radiobiological findings from spaceflight and ground-based studies - an overview

Energy Technology Data Exchange (ETDEWEB)

Buecker, H.; Facius, R.

1980-01-01

An a priori risk assessment of radiobiological effects remains uncertain due to the unpredictable solar flare contribution to the low LET radiation or the unknown reaction mechanisms of heavy ions. Tests suggest that mechanisms inherent to biological systems may be impeded by physiological and psychological stress during spaceflight. The discovery of heavy ion induced late effects in rabbits demonstrates what might be experienced during longer space missions. The evidence for a specific radiobiological reaction mechanism of heavy ions as encountered in space is discussed. A report by Kovalev and Markelov (1979) on LET spectra is reviewed, and the use of absorbed dose as the quantity of reference in estimating an average radiobiological quality factor representative of cosmic particle radiation is criticized.

Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

Energy Technology Data Exchange (ETDEWEB)

Adjei, Daniel, E-mail: nana.adjeidan@gmail.com [Institute of Optoelectronics, Military University of Technology, 2, Kaliskiego Str., 00-908 Warsaw (Poland); Radiation Protection Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon, Accra (Ghana); Ayele, Mesfin Getachew; Wachulak, Przemyslaw; Bartnik, Andrzej; Wegrzynski, Łukasz; Fiedorowicz, Henryk [Institute of Optoelectronics, Military University of Technology, 2, Kaliskiego Str., 00-908 Warsaw (Poland); Vyšín, Luděk [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Faculty of Nuclear Sciences and Engineering Physics, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic); Wiechec, Anna; Lekki, Janusz; Kwiatek, Wojciech M. [Institute of Nuclear Physics, Polish Academy of Sciences, 152, Radzikowskiego Str., 31-342 Cracow (Poland); Pina, Ladislav [Faculty of Nuclear Sciences and Engineering Physics, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic); Davídková, Marie [Institute of Nuclear Physics, Czech Academy of Sciences, Řež (Czech Republic); Juha, Libor [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

2015-12-01

A desk-top laser-produced plasma (LPP) source of soft X-rays (SXR) has been developed for radiobiology research. The source is based on a double-stream gas puff target, irradiated with the focused beam of a commercial Nd:YAG laser. The source has been optimized to get a maximum photon emission from LPP in the X-ray “water window” spectral wavelength range from 2.3 nm (i.e., an absorption edge of oxygen) to 4.4 nm (i.e., an absorption edge of carbon) (280–540 eV in photon energy units) by using argon gas-puff target and spectral filtering by free-standing thin foils. The present source delivers nanosecond pulses of soft X-rays at a fluence of about 4.2 × 10{sup 3} photons/μm{sup 2}/pulse on a sample placed inside the vacuum chamber. In this paper, the source design, radiation output characterization measurements and initial irradiation experiments are described. The source can be useful in addressing observations related to biomolecular, cellular and organisms’ sensitivity to pulsed radiation in the “water window”, where carbon atoms absorb X-rays more strongly than the oxygen, mostly present in water. The combination of the SXR source and the radiobiology irradiation layout, reported in this article, make possible a systematic investigation of relationships between direct and indirect action of ionizing radiation, an increase of a local dose in carbon-rich compartments of the cell (e.g., lipid membranes), an experimental estimation of a particular role of the Auger effect (in particular in carbon atoms) in the damage to biological systems, and the study of ionization/excitation-density (LET – Linear Energy Transfer) and dose-rate effects in radiobiology.

Radiobiological comparison of pions and heavy ions

International Nuclear Information System (INIS)

Raju, M.R.

1981-01-01

The physical and radiobiological differences between some aspects of pions and heavy ions are discussed, followed by a discussion of acute and late effects of high LET radiations compared to low LET radiations

Modeling volume effects of experimental brachytherapy in the rat rectum: uncovering the limitations of a radiobiologic concept

International Nuclear Information System (INIS)

Johannessen, Hans-Olaf; Dale, Einar; Hellebust, Taran P.; Olsen, Dag R.; Nesland, Jahn M.; Giercksky, Karl-Erik

2002-01-01

Purpose: To analyze the significance of volume effects in experimental brachytherapy, based on modeling normal tissue complication probability. Methods and Materials: Experimental brachytherapy in the rat rectum was based on an eight-step 2.5-mm step size source configuration for 192 Ir, afterloaded into an unshielded polystyrene applicator. Volume effects were studied using a half-circumferential lead-shielded applicator and a shorter (two-step) source configuration. The main end point was rectal stenosis. Results: Rectal stenosis was always caused by a radiation ulcer. With the shielded configuration, single-dose ED 50 (50% incidence of rectal stenosis) increased from 23 Gy to 36.5 Gy. Single-dose ED 50 for the short configuration was 77.9 Gy. The data showed a reasonable fit to a three-parameter version of the biophysical model described by Jackson et al. (1995). This model assumes that organs consist of a large number of radiobiologically independent subunits and that radiation causes a complication if the fraction of the organ damaged is greater than its functional reserve. The fraction of the organ damaged is calculated summing over fractions of the organ damaged at each dose level. The calculated mean functional reserve (ν 50 ) of the rat rectum, assuming a cumulative functional reserve distribution in the group of experimental rats, was 0.53. Conclusions: The volume effect observed within small brachytherapy volumes agreed well with clinical experience of large tolerance doses in contact X-ray therapy. However, the ν 50 value was comparable to the high functional reserve value reported for liver. Experimental volume effects probably reflect repair processes originating in the areas adjacent to small radiation fields of brachytherapy more than the radiobiologic characteristics of the cells in the irradiated volume

Optimization in brachytherapy with the implementation of Radiobiology

International Nuclear Information System (INIS)

Duran, M.P.; Bourel, V.J.; Rodriguez, I.; Torre, M. de la; Caneva, S.

1998-01-01

In the brachytherapy planning treatments with High dose rates (HDR), the optimization algorithms used are based in dosimetric considerations and/or geometric ones, ignoring the radiobiological response of the tissue treated. In this work we wish to show the implementation of radiobiological concepts in the optimization. Assuming that the subtiles differences that result in the dose distribution among the different optimization models which are not visible in an isodose plane, it is studied how is classically make it , the quality implant through natural histograms about dose volumes and the resulting parameters. Also is studied the necrosis probability which may be caused by the choice of some optimization model, allowing with this the choice of the best implant. (Author)

Soft x rays for radiobiological studies

International Nuclear Information System (INIS)

Ban, Sadayuki; Iida, Shozo; Shimba, Hachiro; Awa, A.A.; Hamilton, H.B.; Clifton, K.H.

1986-04-01

Lethal effects and chromosome aberrations induced in cells exposed to low energy (soft) X rays demonstrated that these relatively low energy X rays are just as effective as those of higher energy for radiobiological studies, and even more effective for irradiating cultured mammalian cells than laboratory animals. (author)

Overview of research and therapy facilities for radiobiological experimental work in particle therapy. Report from the European Particle Therapy Network radiobiology group.

Science.gov (United States)

Dosanjh, Manjit; Jones, Bleddyn; Pawelke, Jörg; Pruschy, Martin; Sørensen, Brita Singers

2018-04-24

Particle therapy (PT) as cancer treatment, using protons or heavier ions, can provide a more favorable dose distribution compared to X-rays. While the physical characteristics of particle radiation have been the aim of intense research, less focus has been placed on the actual biological responses arising from particle irradiation. One of the biggest challenges for proton radiobiology is the RBE, with an increasing concern that the clinically-applied generic RBE-value of 1.1 is an approximation, as RBE is a complex quantity, depending on both biological and physical parameters, such as dose, LET, cellular and tissue radiobiological characteristics, as well as the endpoints being studied. Most of the available RBE data derive from in vitro experiments, with very limited in vivo data available, especially in late-reacting tissues, which provide the main constraints and influence the quality of life endpoints in radiotherapy. There is a need for systematic, large-scale studies to thoroughly establish the biology of particle radiation in a number of different experimental models in order to refine biophysical mathematical models that can potentially be used to guide PT. The overall objective of the European Particle Therapy Network (EPTN) WP6 is to form a network of research and therapy facilities in order to coordinate and standardize the radiobiological experiments, to obtain more accurate predictive parameters than in the past. Coordinated research is required in order to obtain the most appropriate experimental data. The aim in this paper is to describe the available radiobiology infrastructure of the centers involved in EPTN WP6. Copyright © 2018 Elsevier B.V. All rights reserved.

Press breakfast, radiobiology stakes: an European context, Thursday 25 March 2004

International Nuclear Information System (INIS)

2004-03-01

The radiobiology endeavours to know the ionizing radiations effects on living systems, particular at low doses exposures. The researches in this area contribute to the elaboration of international regulation on nuclear industry. The individual radiosensitivity is an other aspect of the research in radiobiology. These studies should allow the establishing of radiation protection standards founded on a direct approach and an individual estimation of the level of acceptable dose. (N.C.)

Modern concepts for basic radiobiological factors characterizing tumor tissue radiosensitivity

International Nuclear Information System (INIS)

Gocheva, L.; Sergieva, K.

2002-01-01

Traditionally radiotherapy is prescribed at doses consistent with the expected therapeutic response and tolerance of tumor and normal tissues without consideration to individual differences in radiosensitivity. However, the basic radiobiological knowledge and clinical experience along this line point to significant variations in the observed therapeutic results. It has been established that cells and tissues under experimental and clinical conditions manifest a wide spectrum of individual radiosensitivity. The aim of this survey is to outline the current concepts for the basic radiobiological factors influencing tumor radiosensitivity. A thorough discussion is done of the essence, mechanisms of action, methods of determination and measurement, and effect on the prognosis in patients with malignant diseases of a number of radiobiological factors, such as: tumor-cell proliferation, apoptosis, tumor hypoxia and neovascularization. Although the knowledge of the mechanisms of radiosensitivity is constantly expanding, its clinical implementation is still rather limited. The true role of radiosensitivity in predicting the therapeutic response should be more accurately defined. (authors)

Josephinite. A terrestrial alloy with radiogenic xenon-129 and the noble gas imprint of iron meteorites

Energy Technology Data Exchange (ETDEWEB)

Downing, R G; Hennecke, E W; Manuel, O K [Missouri Univ., Rolla (USA). Dept. of Chemistry

1977-12-01

Analyses of noble gases released by stepwise heating of Josephinite reveal two radiogenic components, radiogenic /sup 129/Xe asymptotically equals 1 x 10/sup -12/ ccSTP/g and radiogenic /sup 40/Ar asymptotically equals 1 x 10/sup -6/ cc STP/g, and the following components of trapped noble gases: He with /sup 3/He//sup 4/He asymptotically equals 4 x 10/sup -5/, Ne with /sup 20/Ne//sup 22/Ne=10.5, Ar with /sup 40/Ar//sup 36/Ar=3 x 10/sup 2/, and Kr and Xe with isotopic compositions similar to those observed in iron meteorites. The excess of /sup 40/Ar and literature values of K in bulk Josephinite yield and apparent K-Ar age of asymptotically equals 4.6 x 10/sup 9/ years.

Advances and perspectives in radiobiological technology

International Nuclear Information System (INIS)

Kuzin, A.M.; Kaushanskij, D.A.

1983-01-01

On the basis of the analysis of experience in the USSR and in foreign countries nowadays the state and perspectives for the development of a new, in principle, aspect of technology is considered based on using ionizing radiations and radiobiological effects in agriculture, medical-, food-, microbiological and other branches of industry

Recommendations for the future of translational radiobiology research: a Canadian perspective

International Nuclear Information System (INIS)

Bristow, Robert G.

2004-01-01

The use of molecular medicine is now merging into clinical practice with the advent of molecular targeting agents, molecular pathology and molecular imaging for both diagnosis and treatment response. Radiation oncologists must therefore gain expertise in utilizing this information to drive new treatment protocols. Recognizing the importance of this issue, the Canadian Association of Radiation Oncologists (CARO) charged a Task Force in Translational Radiobiology to: (1) critically assess training programs and research infrastructure in relation to current and future translational radiobiology requirements; and (2) make specific recommendations to accelerate the implementation of translational science into day-to-day practice. Selected Task Force recommendations included the principle that universities and departmental Chairs increase the opportunities for academic promotion, funding, and tenure track positions of radiobiologists and translational radiation oncologists. The dedication of 4 to 5 national centers as translational 'hubs', can serve as an interface between clinicians, clinical specimens and radiobiological sciences within the context of correlative clinical trials. The model of the clinician-scientist was encouraged as an important adjunct to good clinical care to be associated with strong enticement, training and mentoring programs and 75%-protected research time. Finally, an integrated model of radiobiological training programs and mutual continuing education between clinicians and basic scientists can be facilitated through a new national radiobiology meeting sponsored by CARO. These recommendations have been accepted by the national radiation oncology membership. Such a framework may serve useful for national programs wishing to develop rapid conduits from the lab to the clinic as a means of integrating molecular biology and the day-to-day practice of radiation oncology

Surface damage in the small intestine of the mouse after X - or neutron irradiation

International Nuclear Information System (INIS)

Hamlet, R.; Carr, K.E.; Nias, A.H.; Watt, C.

1981-01-01

Damage after X-irradiation includes lateral villous collapse, progressing after 3 - 5 days to villi which sometimes show signs of vertical collapse. After neutron irradiation vertical villous collapse is established earlier, with less swelling of villous tips. It seems, therefore, that at radiobiologically equivalent doses, neutron and X-irradiation produce different levels of surface damage, with neutron irradiation being the more destructive. Early villous tip damage may perhaps be due to disruption of susceptible cells already at the extrusion zone, or to stromal damage

Radiogenic and muon-induced backgrounds in the LUX dark matter detector

Science.gov (United States)

Akerib, D. S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Bernard, E.; Bernstein, A.; Bradley, A.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chapman, J. J.; Chiller, A. A.; Chiller, C.; Coffey, T.; Currie, A.; de Viveiros, L.; Dobi, A.; Dobson, J.; Druszkiewicz, E.; Edwards, B.; Faham, C. H.; Fiorucci, S.; Flores, C.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C.; Hertel, S. A.; Horn, M.; Huang, D. Q.; Ihm, M.; Jacobsen, R. G.; Kazkaz, K.; Knoche, R.; Larsen, N. A.; Lee, C.; Lindote, A.; Lopes, M. I.; Malling, D. C.; Mannino, R.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H.; Neves, F.; Ott, R. A.; Pangilinan, M.; Parker, P. D.; Pease, E. K.; Pech, K.; Phelps, P.; Reichhart, L.; Shutt, T.; Silva, C.; Solovov, V. N.; Sorensen, P.; O'Sullivan, K.; Sumner, T. J.; Szydagis, M.; Taylor, D.; Tennyson, B.; Tiedt, D. R.; Tripathi, M.; Uvarov, S.; Verbus, J. R.; Walsh, N.; Webb, R.; White, J. T.; Witherell, M. S.; Wolfs, F. L. H.; Woods, M.; Zhang, C.

2015-03-01

The Large Underground Xenon (LUX) dark matter experiment aims to detect rare low-energy interactions from Weakly Interacting Massive Particles (WIMPs). The radiogenic backgrounds in the LUX detector have been measured and compared with Monte Carlo simulation. Measurements of LUX high-energy data have provided direct constraints on all background sources contributing to the background model. The expected background rate from the background model for the 85.3 day WIMP search run is (2.6 ±0.2stat ±0.4sys) ×10-3 events keVee-1 kg-1day-1 in a 118 kg fiducial volume. The observed background rate is (3.6 ±0.4stat) ×10-3 events keVee-1 kg-1day-1 , consistent with model projections. The expectation for the radiogenic background in a subsequent one-year run is presented.

Experimental radiotherapy and clinical radiobiology. Vol. 20. Proceedings; Experimentelle Strahlentherapie und Klinische Strahlenbiologie. Bd. 20. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemannn, Hans-Peter; Zips, Daniel (eds.)

2011-07-01

The proceedings include contributions on the following issues: laser driven proton accelerators on the way for radiotherapy, radiobiological evaluation of new radiations; molecular factors of radiation response; biological targeting; EGFR epidermal growth factor receptor/targeting - combined internal and external irradiation, radiobiology of normal tissues; dose-volume histograms for the radiotherapy: curves without radiobiological relevance or important information for the therapy planning; HPV (human papilloma virus) and radiation sensitivity of HNSCC (head and neck squamous cell carcinomas): evidence, radiobiological mechanism, clinical consequences and perspectives; mechanisms of action and intertumoral heterogeneity of response to EGFR inhibition in radiotherapy of solid tumors; evaluation of biomarkers for radiotherapy.

IAEA advisory group meeting on nuclear and atomic data for radiotherapy and related radiobiology in co-operation with the Radiobiological Institute of the Division for Health Research TNO, 16-20 September 1985, Rijswijk, the Netherlands

International Nuclear Information System (INIS)

Okamoto, K.

1985-11-01

The IAEA Advisory Group Meeting on ''Nuclear and Atomic Data for Radiotherapy and Related Radiobiology'' was held at Rijswijk, the Netherlands, from 16 to 20 September 1985, in co-operation with the Radiobiological Institute TNO. The meeting participants reviewed the current and future requirements on nuclear and atomic data for radiotherapy and radiobiology, identified data requirements and their priorities, and issued a number of specific recommendations for future technical work in nuclear and atomic data required to establish a more solid nuclear physics foundation of radiotherapy and related radiobiology. The recommendations in this report are directed to three areas, namely beam production and field description, dosimetry, and interpretation and optimization of biological effects. The final proceedings will be issued as an IAEA publication in 1986. (author)

Radiogenic cancer in underground miners

International Nuclear Information System (INIS)

Radford, E.P.

1984-01-01

Multiple studies have yielded remarkably consistent results relating radon daughter exposure to lung cancer risk in underground mining populations. The U.S. uranium miner study appears to be at variance with the other results. The primary reason is that the doses in the U.S. miner study were systematically overestimated, resulting in a risk coefficient that is lower than all the others. The significance of these findings for radiogenic lung cancer goes well beyond mining populations, because one is now aware of the implications of radon daughters detected in homes. The highest cumulative levels from radon exposures within homes have been found in Sweden, evidently because of their unusual geology with uranium-bearing ores near the surface. The Swedish authorities view this as a major public health problem that needs to be addressed

Radiogenic Lead with Dominant Content of 208Pb: New Coolant and Neutron Moderator for Innovative Nuclear Facilities

Directory of Open Access Journals (Sweden)

A. N. Shmelev

2011-01-01

Full Text Available As a rule materials of small atomic weight (light and heavy water, graphite, and so on are used as neutron moderators and reflectors. A new very heavy atomic weight moderator is proposed—radiogenic lead consisting mainly of isotope 208Pb. It is characterized by extremely low neutron radiative capture cross-section (0.23 mbarn for thermal neutrons, i.e., less than that for graphite and deuterium and highest albedo of thermal neutrons. It is evaluated that the use of radiogenic lead makes it possible to slow down the chain fission reaction on prompt neutrons in a fast reactor. This can increase safety of the fast reactors and reduce as well requirements pertaining to the fuel fabrication technology. Radiogenic lead with high 208Pb content as a liquid-metal coolant of fast reactors helps to achieve a favorable (negative reactivity coefficient on coolant temperature. It is noteworthy that radiogenic lead with high 208Pb content may be extracted from thorium (as well as thorium-uranium ores without isotope separation. This has been confirmed experimentally by the investigations performed at San Paulo University, Brazil.

A review of the statistical principles of geochronometry. II. Additional concepts pertinent to radiogenic U-Pb studies

International Nuclear Information System (INIS)

Eglington, B.M.; Harmer, R.E.

1993-01-01

A summary is provided of statistical regression techniques as applied to radiogenic uranium-lead data. The model-dependent nature of U-Pb regression calculations, both for isochrons and errorchrons, is emphasized throughout. Near concordant U-Pb radiogenic data preserve better information about the original age of the samples than do more discordant data, yet most conventional regression techniques assign more importance to the discordant data than to those near concordia. The links between mathematical techniques for regression and conceptual models are highlighted and critically examined and methods illustrated to deal with the discordant data. Comparison of dates from different laboratories or researchers requires that the techniques applied be statistically valid and, in most cases, that the model-dependent assumptions be compatible. This is particularly important for U-Pb radiogenic data where the influence of model-dependent assumptions may have a greater influence than in the case of whole-rock techniques. A consistent approach is proposed for treating data at South African laboratories in order ro facilitate comparison of results. Recommendations are presented as regards the minimum requirements to be met when reporting radiogenic U-Pb isotope data so that future geochronologists may benefit. 35 refs., 2 tabs., 6 figs

Partial radiogenic heat model for Earth revealed by geoneutrino measurements

NARCIS (Netherlands)

Abe, S.; et al., [Unknown; Decowski, M.P.

2011-01-01

The Earth has cooled since its formation, yet the decay of radiogenic isotopes, and in particular uranium, thorium and potassium, in the planet’s interior provides a continuing heat source. The current total heat flux from the Earth to space is 44.2±1.0 TW, but the relative contributions from

The significance of the choice of radiobiological (NTCP) models in treatment plan objective functions

International Nuclear Information System (INIS)

Miller, J.; Fuller, M.; Vinod, S.; Holloway, L.

2009-01-01

Full text: A Clinician's discrimination between radiation therapy treatment plans is traditionally a subjective process, based on experience and existing protocols. A more objective and quantitative approach to distinguish between treatment plans is to use radiobiological or dosimetric objective functions, based on radiobiological or dosimetric models. The efficacy of models is not well understood, nor is the correlation of the rank of plans resulting from the use of models compared to the traditional subjective approach. One such radiobiological model is the Normal Tissue Complication Probability (NTCP). Dosimetric models or indicators are more accepted in clinical practice. In this study, three radiobiological models, Lyman NTCP, critical volume NTCP and relative seriality NTCP, and three dosimetric models, Mean Lung Dose (MLD) and the Lung volumes irradiated at lOGy (V|0) and 20 G y (V20), were used to rank a series of treatment plans using, harm to normal (Lung) tissue as the objective criterion. None of the models considered in this study showed consistent correlation with the Radiation Oncologists plan ranking. If radiobiological or dosimetric models are to be used in objective functions for lung treatments, based on this study it is recommended that the Lyman NTCP model be used because it will provide most consistency with traditional clinician ranking.

Radiation-related caries. Etiology and possible preventive strategies. What should the radiotherapist know?; Radiogene Karies. Aetiologie und Moeglichkeiten der Praevention. Was sollte der Strahlentherapeut wissen?

Energy Technology Data Exchange (ETDEWEB)

Schweyen, R.; Hey, J. [Martin-Luther-Univ., Halle-Wittenberg (Germany). Universitaetspoliklinik fuer Prothetik; Fraenzel, W. [Martin-Luther-Univ., Halle-Wittenberg (Germany). Inst. fuer Physik; Vordermark, D. [Martin-Luther-Univ., Halle-Wittenberg (Germany). Universitaetsklinik und Poliklinik fuer Strahlentherapie; Hildebrandt, G.; Kuhnt, T. [Universitaetsklinikum Rostock (Germany). Universitaetsklinik und Poliklinik fuer Strahlentherapie

2012-01-15

After radiation treatment of head-and-neck cancer, the impairment of patient's quality of life still remains an issue. After completion of the treatment course, a substantial number of patients develop so-called radiation caries. In addition, almost 50% of all cases of infectious osteoradionecrosis (iORN) of the jaws are directly associated with radiation caries. This review addresses our current knowledge on the etiology and pathogenesis of radiation caries including possible preventive strategies. Materials and methods A PubMed search using the terms ''radiation caries'' (''radiation related caries'', ''radiation related damage to dentition'') and ''radiogenic caries'' (''postradiation caries'', ''dental complications and radiotherapy'') was performed. The analysis of its content focused on the etiology, the pathogenesis, and the available knowledge on prophylaxis as well as treatment of radiation caries. Results For this review, 60 publications were selected. As main causal factors for radiogenic caries, either indirect impairment, resulting from alterations in the oral environment (e.g., radiation-induced xerostomia) or direct radiation-induced damage in teeth hard tissues are discussed. Radiation caries remains a lifelong threat and, therefore, requires permanent prevention programs. Conclusion To enable optimal medical care of the patients during the time course of radiotherapy as well as afterwards, close interdisciplinary cooperation between radiotherapists, oral surgeons, otorhinolaryngologists, and dentists is absolutely essential. (orig.)

Radiobiology with heavy charged particles: a historical review

International Nuclear Information System (INIS)

Skarsgard, L.D.

1997-01-01

The presentation will attempt to briefly review some of radiobiological data on the effects of heavy charged particles and to discuss the influence of those studies on the clinical application which followed. (orig./MG)

A systemic approach to modelling of radiobiological effects

International Nuclear Information System (INIS)

Obaturov, G.M.

1988-01-01

Basic principles of the systemic approach to modelling of the radiobiological effects at different levels of cell organization have been formulated. The methodology is proposed for theoretical modelling of the effects at these levels

Radiobiology with heavy charged particles: a historical review

Energy Technology Data Exchange (ETDEWEB)

Skarsgard, L D [Dept. of Medical Biophysics, B.C. Cancer Research Centre and TRIUMF, Vancouver (Canada)

1997-09-01

The presentation will attempt to briefly review some of radiobiological data on the effects of heavy charged particles and to discuss the influence of those studies on the clinical application which followed. (orig./MG)

The radiobiology of laser-driven particle beams: focus on sub-lethal responses of normal human cells

International Nuclear Information System (INIS)

Manti, L.; Perozziello, F.M.; Romagnani, L.; Borghesi, M.; Doria, D.; Candiano, G.; Cirrone, G.A.P.; Leanza, R.; Romano, F.; Scuderi, V.; Tramontana, A.; Chaudhary, P.; Gwynne, D.; Prise, K. M.

2017-01-01

Accelerated proton beams have become increasingly common for treating cancer. The need for cost and size reduction of particle accelerating machines has led to the pioneering investigation of optical ion acceleration techniques based on laser-plasma interactions as a possible alternative. Laser-matter interaction can produce extremely pulsed particle bursts of ultra-high dose rates (≥ 10 9 Gy/s), largely exceeding those currently used in conventional proton therapy. Since biological effects of ionizing radiation are strongly affected by the spatio-temporal distribution of DNA-damaging events, the unprecedented physical features of such beams may modify cellular and tissue radiosensitivity to unexplored extents. Hence, clinical applications of laser-generated particles need thorough assessment of their radiobiological effectiveness. To date, the majority of studies have either used rodent cell lines or have focussed on cancer cell killing being local tumour control the main objective of radiotherapy. Conversely, very little data exist on sub-lethal cellular effects, of relevance to normal tissue integrity and secondary cancers, such as premature cellular senescence. Here, we discuss ultra-high dose rate radiobiology and present preliminary data obtained in normal human cells following irradiation by laser-accelerated protons at the LULI PICO2000 facility at Laser Lab Europe, France.

Radiogenic neoplasia in thyroid and mammary clonogens

International Nuclear Information System (INIS)

Clifton, K.H.

1992-01-01

We have developed rat thyroid and mammary clonogen transplantation systems for the study of radiogenic cancer induction at the target cell level in vivo. The epithelial cell populations of both glands contain small subpopulations of cells which are capable of giving rise to monoclonal glandular structures when transplanted and stimulated with appropriate hormones. Previous results indicated that these clonogens are the precursor cells of radiogenic cancer, and that initiation, is common event at the clonegenic cell level. Detailed information on the physiologic control of clonogen proliferation, differentiation, and total numbers is thus essential to an understanding of the carcinogenic process. We report here studies on investigations on the relationships between grafted thyroid cell number and the rapidity and degree of reestablishment of the thyroid-hypothalamus-pituitary feedback axis in thyroidectomized rats maintained on a normal diet or an iodine deficient diet; studies of the persistence of, and the differentiation potential and functional characteristics of, the TSH-(thyrotropin-) responsive sub- population of clonogens during goitrogenesis, the plateau-phase of goiter growth, and goiter involution; studies of changes in the size of the clonogen sub-population during goitrogenesis, goiter involution and the response to goitrogen rechallenge; and a large carcinogenesis experiment on the nature of the grafted thyroid cell number-dependent suppression of promotion/progression to neoplasia in grafts of radiation-initiated thyroid cells. Data from these studies will be used in the design of future carcinogenesis experiments on neoplastic initiation by high and low LET radiations and on cell interactions during the neoplastic process

Radiobiological Impact of Planning Techniques for Prostate Cancer ...

African Journals Online (AJOL)

of gantry rotation speed, dose rate, and multi leaf collimator ... Background: The radiobiological models describe the effects of the radiation treatment on cancer and healthy ... delivery time and decrement in the number of monitor units.[3-5].

Mathematical and physical models and radiobiology

International Nuclear Information System (INIS)

Lokajicek, M.

1980-01-01

The hit theory of the mechanism of biological radiation effects in the cell is discussed with respect to radiotherapy. The mechanisms of biological effects and of intracellular recovery, the cumulative radiation effect and the cumulative biological effect in fractionated irradiation are described. The benefit is shown of consistent application of mathematical and physical models in radiobiology and radiotherapy. (J.P.)

National Radiobiology Archives Distributed Access user's manual

International Nuclear Information System (INIS)

Watson, C.; Smith, S.; Prather, J.

1991-11-01

This User's Manual describes installation and use of the National Radiobiology Archives (NRA) Distributed Access package. The package consists of a distributed subset of information representative of the NRA databases and database access software which provide an introduction to the scope and style of the NRA Information Systems

Investigations of DNA damage induction and repair resulting from cellular exposure to high dose-rate pulsed proton beams

International Nuclear Information System (INIS)

Renis, M.; Malfa, G.; Tomasello, B.; Borghesi, M.; Schettino, G.; Favetta, M.; Romano, F.; Cirrone, G. A. P.; Manti, L.

2013-01-01

Studies regarding the radiobiological effects of low dose radiation, microbeam irradiation services have been developed in the world and today laser acceleration of protons and heavy ions may be used in radiation therapy. The application of different facilities is essential for studying bystander effects and relating signalling phenomena in different cells or tissues. In particular the use of ion beams results advantageous in cancer radiotherapy compared to more commonly used X-rays, since the ability of ions in delivering lethal amount of doses into the target tumour avoiding or limiting damage to the contiguous healthy tissues. At the INFN-LNS in Catania, a multidisciplinary radiobiology group is strategically structured aimed to develop radiobiological research, finalised to therapeutic applications, compatible with the use of high dose laser-driven ion beams. The characteristic non-continuous dose rates with several orders of magnitude of laser-driven ion beams makes this facility very interesting in the cellular systems' response to ultra-high dose rates with non-conventional pulse time intervals cellular studies. Our group have projected to examine the effect of high dose laser-driven ion beams on two cellular types: foetal fibroblasts (normal control cells) and DU145 (prostate cancer cells), studying the modulation of some different bio-molecular parameters, in particular cell proliferation and viability, DNA damage, redox cellular status, morphological alterations of both the cytoskeleton components and some cell organelles and the possible presence of apoptotic or necrotic cell death. Our group performed preliminary experiments with high energy (60 MeV), dose rate of 10 Gy/min, doses of 1, 2, 3 Gy and LET 1 keV/μm on human foetal fibroblasts (control cells). We observed that cell viability was not influenced by the characteristics of the beam, the irradiation conditions or the analysis time. Conversely, DNA damage was present at time 0, immediately

Investigations of DNA damage induction and repair resulting from cellular exposure to high dose-rate pulsed proton beams

Energy Technology Data Exchange (ETDEWEB)

Renis, M.; Malfa, G.; Tomasello, B. [Drug Sciences Department, University of Catania, Catania (Italy); Borghesi, M.; Schettino, G. [Queen' s University Belfast, Northern Ireland (United Kingdom); Favetta, M.; Romano, F.; Cirrone, G. A. P. [National Institute for Nuclear Physics (INFN-LNS), Catania (Italy); Manti, L. [Physics Science Department, University of Naples Federico II, Naples, and National Institute for Nuclear Physics (INFN), Naples (Italy)

2013-07-26

Studies regarding the radiobiological effects of low dose radiation, microbeam irradiation services have been developed in the world and today laser acceleration of protons and heavy ions may be used in radiation therapy. The application of different facilities is essential for studying bystander effects and relating signalling phenomena in different cells or tissues. In particular the use of ion beams results advantageous in cancer radiotherapy compared to more commonly used X-rays, since the ability of ions in delivering lethal amount of doses into the target tumour avoiding or limiting damage to the contiguous healthy tissues. At the INFN-LNS in Catania, a multidisciplinary radiobiology group is strategically structured aimed to develop radiobiological research, finalised to therapeutic applications, compatible with the use of high dose laser-driven ion beams. The characteristic non-continuous dose rates with several orders of magnitude of laser-driven ion beams makes this facility very interesting in the cellular systems' response to ultra-high dose rates with non-conventional pulse time intervals cellular studies. Our group have projected to examine the effect of high dose laser-driven ion beams on two cellular types: foetal fibroblasts (normal control cells) and DU145 (prostate cancer cells), studying the modulation of some different bio-molecular parameters, in particular cell proliferation and viability, DNA damage, redox cellular status, morphological alterations of both the cytoskeleton components and some cell organelles and the possible presence of apoptotic or necrotic cell death. Our group performed preliminary experiments with high energy (60 MeV), dose rate of 10 Gy/min, doses of 1, 2, 3 Gy and LET 1 keV/μm on human foetal fibroblasts (control cells). We observed that cell viability was not influenced by the characteristics of the beam, the irradiation conditions or the analysis time. Conversely, DNA damage was present at time 0, immediately

Damage of lymphocytes by ionizing irradiation

International Nuclear Information System (INIS)

Rose, H.; Moldenhauer, H.; Kehrberg, G.

1985-01-01

After a short review, how lymphocytes of the peripheral blood are influenced by radiotherapy, the damage of lymphocytes by whole-body irradiation is pointed out in animal experiments and after in vitro irradiation. The special sensibility of B-cells and their homogeneity in fields of radiobiology are opposed to the heterogeneity of T-cells. The radiosensibility of cytotoxic lymphocytes, suppressor cells, and helper cells are discussed. It appears, that within these functional criteria, there is a different radiosensibility, too. (author)

Radiobiological and PK assays at advance Centre for Training Research and Education in Cancer (ACTREC)

International Nuclear Information System (INIS)

Sastri, Goda Jayant; Gota, Vikram

2014-01-01

Radiobiological, pharmacokinetic and biodistribution studies are of paramount importance for drug development and more so in the development of newer radiation modulators. Radiobiological studies have now graduated from simple cell survival and viability assays to more complex molecular and imaging studies to study radiation modulation both in in-vitro and in-vivo models. Tata Memorial Centre and its research centre (ACTREC) is a premiere cancer centre in India dedicated to cancer research. The Department of Radiation Oncology treats approximately 7000 new patients in a year and is uniquely placed to do both translational radiation and clinical research in the field of drug development. The Clinical Biology Lab of the Department of Radiation Oncology at ACTREC in collaboration with other labs at ACTREC has standardized cell survival assays, DNA damage assays such as Gamma H2AX assay (by flow as well as confocal microscopy), Micronuclei assay and COMET assays using CASP software for quantification. We have also done apoptotic assays. These assays have been conducted for development newer drug formulations (for e.g liposomal radiosensitizers). We also have a strong imaging division having sophisticated microscopes (confocal and single molecule super resolution microscopes) for in-vitro optical imaging and a dedicated preclinical PET/CT/SPECT for in-vivo imaging. The clinical 3T MRI and PET/CT is being used to study the effect of hypoxia in various cancers

An Estimation of Radiobiological Parameters for Head-and-Neck Cancer Cells and the Clinical Implications

International Nuclear Information System (INIS)

Qi, X. Sharon; Yang, Qiuhui; Lee, Steve P.; Li, X. Allen; Wang, Dian

2012-01-01

In vitro survival measurements using two human head-and-neck cancer (HNC) cell lines were performed. The specially designed split-dose surviving fraction was obtained and fitted to the linear-quadratic formalism. The repair halftime (Tr), the potential doubling time (T d ), α/β and radiosensitivity α, were estimated. Other radiobiological models: EUD, BED, TCP, etc., were used to examine the potential treatment effectiveness of different IMRT techniques. Our data indicated the repair halftime of ~17 min based on two HNC cell lines. The combined α/β, α and T d are α/β = 8.1 ± 4.1 Gy, α = 0.22 ± 0.08 Gy −1 , T d = 4.0 ± 1.8 day, respectively. The prolonged IMRT dose delivery for entire HNC treatment course could possibly result in the loss of biological effectiveness, i.e., the target EUDs decreased by 11% with fraction dose delivery time varying from 5 to 30 min. We determined the sublethal damage repair halftime and other radiobiological parameters for HNC cells, and to evaluate treatment effectiveness of the prolonged dose delivery times associated with different IMRT techniques. The estimated repair halftime for HNC is relatively short and may be comparable to the step-and-shoot IMRT fraction dose delivery time. The effectiveness of IMRT treatment may be improved by reducing the fraction delivery time for HNC treatment

KamLAND results and the radiogenic terrestrial heat

International Nuclear Information System (INIS)

Fiorentini, Gianni; Lissia, Marcello; Mantovani, Fabio; Ricci, Barbara

2005-01-01

We find that recent results from the KamLAND Collaboration on geologically produced antineutrinos, N(U+Th)=28 -15 +16 events, correspond to a radiogenic heat production from uranium and thorium decay chains H(U+Th)=38 -33 +35 TW. The 99% confidence limit on the geo-neutrino signal translates into the upper bound H(U+Th) 13 C(α,n) 16 O cross section. The result, N(U+Th)=31 -13 +14 , corroborates the evidence (∼2.5σ) for geo-neutrinos in KamLAND data

Radiobiological basis of radiation protection and ICRP 2007 general recommendations

International Nuclear Information System (INIS)

Rao, B.S.

2014-01-01

The ICRP 2007 General Recommendations are based on the detailed review of the new information on the biological effects and risk evaluation done during the last decade. Most of this information reinforces the validity of earlier findings. Since the publication of ICRP 60 general recommendations in 1991(ICRP 1991b), sufficient new information on the health effects of ionizing radiations has accrued based on radiobiological and epidemiological studies (UNSCEAR 2000, ICRP Publication 99). There is an improvement in understanding the mechanistic aspects of the induction of radiation damage at cellular level. Biophysical studies based on Monte Carlo track structure codes have provided information on the nature of critical damage to DNA leading to the radiation effects at cellular level. Experimental work with model animal systems has provided information on the role of post irradiation repair processes and the genes influencing the process of radiation carcinogenesis. Longer follow up of A-Bomb survivors of Hiroshima and Nagasaki now provides a more reliable risk estimate based on the cancer incidence data and also a better model for the transfer of risk among different populations with varying frequency of background incidence. At present it is clear that the breast cancer contributes substantially to the radiation risk and provides quantitative risk estimates for brain and salivary glands. In the light of the new information, Tissue Weighting factors (WT) have been revised

Radiogenic age and isotopic studies

International Nuclear Information System (INIS)

1991-01-01

This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Reports in this issue give U-Pb zircon ages for rocks in Newfoundland, Yukon Territory, Manitoba, Ontario, and the Northwest Territories; present a compilation of K-Ar ages; and discuss Precambrian activity in New Brunswick, the geochronology of rock from the Northwest Territories, and reconnaissance Nd studies of rocks from the Northwest Territories. (figs., tabs., refs.)

Radiogenic age and isotopic studies

International Nuclear Information System (INIS)

1992-01-01

This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Report 5 contains 24 papers from most regions of Canada, but particularly from British Columbia. The Geochronology Laboratory has, over the years, provided substantial U-Pb dating for the Cordilleran Division of the Geological Survey of Canada in Vancouver, and the results of a number of these studies are presented this year. A compilation of K-Ar ages is given. (figs., tabs., refs.)

Radiobiological inactivation of Epstein-Barr virus

International Nuclear Information System (INIS)

Henderson, E.; Heston, L.; Grogan, E.; Miller, G.

1978-01-01

Lymphocyte transforming properties of B95-8 strain Epstein-Barr virus (EBV) are very sensitive to inactivation by either uv or x irradiation. No dose of irradiation increases the transforming capacity of EBV. The x-ray dose needed for inactivation of EBV transformation (dose that results in 37% survival, 60,000 rads) is similar to the dose required for inactivation of plaque formation by herpes simplex virus type 1 (Fischer strain). Although herpes simplex virus is more sensitive than EBV to uv irradiation, this difference is most likely due to differences in the kinetics or mechanisms of repair of uv damage to the two viruses. The results lead to the hypothesis that a large part, or perhaps all, of the EBV genome is in some way needed to initiate transformation. The abilities of EBV to stimulate host cell DNA synthesis, to induce nuclear antigen, and to immortalize are inactivated in parallel. All clones of marmoset cells transformed by irradiated virus produce extracellular transforming virus. These findings suggest that the abilities of the virus to transform and to replicate complete progeny are inactivated together. The amounts of uv and x irradiation that inactivate transformation by B95-8 virus are less than the dose needed to inactivate early antigen induction by the nontransforming P 3 HR-1 strain of EBV. Based on radiobiological inactivation, 10 to 50% of the genome is needed for early antigen induction

Radiobiology studies for the evaluation of epithermal neutron beams used for BNCT

International Nuclear Information System (INIS)

Green, S.; Jones, B.; Mill, A.J.

2006-01-01

This paper outlines our plans for a study to establish the radiobiological effectiveness of the various mixes of radiation components present in an epithermal neutron beam designed for BNCT and to incorporate these data into clinical protocols for the treatment of malignant glioma. This is a description of work which is funded and just now beginning in Birmingham so no results can be presented. Our project will involve a combination of experimental measurements carried out in Birmingham and in Boston and mathematical modelling carried out in Birmingham. Despite all the extant in-vitro and in-vivo work, there is no widely accepted method to determine biological effect by accounting for variations in beam component mix, dose rate and treatment fractionation for disparate from the various BNCT centres. The objectives of this study are: To develop a cell-based radiobiology protocol to provide essential data on safety and efficacy of beams for Boron Neutron Capture Therapy (BNCT) in advance of clinical trials. To exploit the facilities at Massachusetts Institute of Technology for variable dose-rate epithermal irradiations to validate the above protocol. To develop mathematical models of this radiobiological system that can be used to inform decisions on dose selection, fractionation schedules, BNCT use as supplementary boosts or for re-treatment of recurrent cancers. To provide fundamental data relevant to the understanding of the radiobiology of simultaneous mixed high-and low-LET radiations over a clinically relevant dose-range. (author)

Realization of radiobiological in vitro cell experiments at conventional X-ray tubes and unconventional radiation sources

International Nuclear Information System (INIS)

Beyreuther, Elke

2010-01-01

of damage for decreasing photon energy. For this reason, the assumed photon energy dependence was reconfirmed for a cell line other than human lymphocytes, an important finding that was discussed on the 2007 Retreat of the German Commission on Radiological Protection. After successful finalization of the photon experiments the focus of the present dissertation was directed to the realization of in vitro cell irradiation experiments with laser-accelerated electrons. This research was carried out in the frame of the project onCOOPtics that aims on the development of laser-based particle accelerators, which promise accelerators of potentially compact size and more cost-effectiveness suitable for a widespread medical application, especially for high precision hadron therapy. The unique properties, i.e., the ultrashort bunch length and resultant ultrahigh pulse dose rate, of these unconventional particle accelerators demand for extensive investigations with respect to potential effects on the dosimetric and radiobiological characterization. Based on the experiences gained at ELBE first experiments on the radiobiological characterization of laser-accelerated electrons have been performed at the Jena Titanium:Sapphire laser system. After beam optimization, a sophisticated dosimetry system was established that allow for the online control of the beam parameters and for the controlled delivery of dose to the cell sample. Finally, worldwide first systematic in vitro cell irradiation experiments were carried out resulting in a reduced biological effectiveness for laser-accelerated electrons relative to the 200 kV X-ray reference, irrespectively on the biological effect and cell lines examined. These successful results are the basis for future in vivo studies and experiments with laser-accelerated protons.

Realization of radiobiological in vitro cell experiments at conventional X-ray tubes and unconventional radiation sources

Energy Technology Data Exchange (ETDEWEB)

Beyreuther, Elke

2010-09-10

of damage for decreasing photon energy. For this reason, the assumed photon energy dependence was reconfirmed for a cell line other than human lymphocytes, an important finding that was discussed on the 2007 Retreat of the German Commission on Radiological Protection. After successful finalization of the photon experiments the focus of the present dissertation was directed to the realization of in vitro cell irradiation experiments with laser-accelerated electrons. This research was carried out in the frame of the project onCOOPtics that aims on the development of laser-based particle accelerators, which promise accelerators of potentially compact size and more cost-effectiveness suitable for a widespread medical application, especially for high precision hadron therapy. The unique properties, i.e., the ultrashort bunch length and resultant ultrahigh pulse dose rate, of these unconventional particle accelerators demand for extensive investigations with respect to potential effects on the dosimetric and radiobiological characterization. Based on the experiences gained at ELBE first experiments on the radiobiological characterization of laser-accelerated electrons have been performed at the Jena Titanium:Sapphire laser system. After beam optimization, a sophisticated dosimetry system was established that allow for the online control of the beam parameters and for the controlled delivery of dose to the cell sample. Finally, worldwide first systematic in vitro cell irradiation experiments were carried out resulting in a reduced biological effectiveness for laser-accelerated electrons relative to the 200 kV X-ray reference, irrespectively on the biological effect and cell lines examined. These successful results are the basis for future in vivo studies and experiments with laser-accelerated protons.

Radiogenic heat production and the earth's heat balance. A source of arguments in geoscience

International Nuclear Information System (INIS)

Kuczera, B.

2008-01-01

The terrestrial heat flow into interstellar space amounts to approx. 32 TW on the basis of an average heat flow density of 63 mW per sq.m. of earth surface. The loss flow derives part of the energy from the residual heat of the nascent phase of the earth (approx. 40%) and the other part from the natural disintegration of longlived radionuclides, i.e. radiogenic heat production (roughly 60%). This concept met with broad consensus in the geosciences until the 1980s. In 1993, Pollack et al. concluded from the evaluation of recent measured data that heat loss via the oceanic crust of the earth was clearly higher, which raises the loss flow to a total of 44 TW. This is contradicted by Hoffmeister and Criss, who conclude from a modified geochemical model that the total heat loss of 31 TW is fully compensated by radiogenic heat production. In 2001, C. Herndon introduced a new idea into the discussion. According to his thesis, planetary differentiation caused a nuclear georeactor to be created in the center of the earth, whose continuous thermal power of approx. 3 TW contributes to compensating heat losses. Physicists and geoscientists hope to be able to derive new findings on this thesis and on the distribution of radiogenic heat production in the interior of the earth from the planned geo-neutrino experiment in Homestake, USA. (orig.)

Prevention of radiogenic cancers through changes in procedure

International Nuclear Information System (INIS)

Matthews, I.P.

1988-01-01

A report is given of a comprehensive study of radiographic practice carried out between 1983-86 in 18 district general hospitals throughout Wales. Results are presented for the range of variation in exposure-area product (EAP) for each type of radiographic examination, the mean EAPs for various projections of each examination and the inter-departmental variation in choices of projections and film size for examination of the cervical spine. It is estimated that 80% of the radiogenic cancers associated with these examinations could be prevented through implementation of suitable guidelines to reduce inter-departmental variation in patients' exposure. (UK)

National radiobiology archives Dr. J. Newell Stannard Collection Inventory Listing

International Nuclear Information System (INIS)

Watson, C.R.; Ligotke, E.K.; Smith, S.K.

1994-11-01

This document describes the National Radiobiology Archives (NRA) J. Newell Stannard Collection. Items in the Stannard Collection are available upon written request. The written correspondence should identify specific items, or the topic of the items, to be retrieved from the NRA holdings. The NRA is a Department of Energy Office of Health and Environmental Research (DOE/OHER) funded project at Pacific Northwest Laboratory (PNL). Dr. Charles R. Watson, telephone (509) 376-3483, is the project director. The NRA project is a comprehensive effort to gather, organize, and catalog data, tissues, and documents related to radiobiology studies. This archiving activity will provide future researchers with information for statistical analyses to compare results of these and other studies and materials for analysis and application of advanced molecular biology techniques

Radiobiology of Proton Therapy - Results of an international expert workshop

DEFF Research Database (Denmark)

Lühr, Armin; von Neubeck, Cläre; Pawelke, Jörg

2018-01-01

The physical properties of proton beams offer the potential to reduce toxicity in tumor-adjacent normal tissues. Toward this end, the number of proton radiotherapy facilities has steeply increased over the last 10-15 years to currently around 70 operational centers worldwide. However, taking full...... in proton therapy combined with systemic treatments, and (4) testing biological effects of protons in clinical trials. Finally, important research avenues for improvement of proton radiotherapy based on radiobiological knowledge are identified. The clinical distribution of radiobiological effectiveness...... of protons alone or in combination with systemic chemo- or immunotherapies as well as patient stratification based on biomarker expressions are key to reach the full potential of proton beam therapy. Dedicated preclinical experiments, innovative clinical trial designs, and large high-quality data...

Low doses of ionizing radiation: Relationship between biological benefit and damage induction. A synopsis

International Nuclear Information System (INIS)

Feinendegen, L.E.

2005-01-01

Absorption of ionizing radiation in biological tissue stochastically interacts with constituent atoms and molecules and always generates energy deposition (track) events accompanied by bursts of reactive oxygen species (ROS). These ROS are quite similar to those ROS that arise abundantly and constantly by normal oxidative metabolism. ROS effects from either source need attention when assessing radiation-induced alterations in biological structure and function. Endogenous ROS alone induce about 10 6 DNA oxyadducts per cell per day compared to about 5x10 -3 total DNA damage per average cell per day from background radiation exposure (1 mGy per year). At this background level, the corresponding ratio of probabilities of endogenous versus radiogenic DNA double strand breaks (DSBs) per cell per day is about 103 with some 25-40 % of low-LET caused radiogenic DNA-DSBs being of the multi-damage-site type. Radiogenic DNA damage increases in proportion to absorbed dose over a certain dose range. By evolution, tissues possess physiological mechanisms of protection against an array of potentially toxic agents, externally from the environment and endogenously from metabolism, mainly against the abundantly and constantly produced ROS. Ad hoc protection operates at a level that is genetically determined. Following small to moderate perturbation of cell-tissue homeostasis by a toxic impact, adaptive responses develop with a delay and may last from hours to weeks, even months, and aim at protecting the system against renewed insults. Protective responses encompass defense by scavenging mechanisms, DNA repair, damage removal largely by apoptosis and immune responses, as well as changes in cell proliferation. Acute low-dose irradiation below about 0.2 Gy can not only disturb cell-tissue homeostasis but also initiate adaptived protection that appears with a delay of hours and may last from less than a day to months. The balance between damage production and adaptive protection favors

Skin, eye, and testis: current exposure problems and recent advances in radiobiology

International Nuclear Information System (INIS)

Charles, M.W.

1986-01-01

Three organs, the skin, eye and testis are potentially at risk from poorly penetrating radiations such as beta particles or low energy X-Rays. They may be preferentially irradiated in fields with steep depth - dose gradients and thereby dictate radiological protection procedures. Since there is not a wide margin of safety in the annual permissible dose limits for these organs it is important to have clearly defensible methods of dose assessment. This requires both an adequate understanding of the radiobiology of these organs and the availability of experimental techniques for measuring doses at various depths near the surface of the body. This paper reviews the current state of knowledge in this field, drawing partly on information from two recent CEC workshops on the 'Dosimetry of Beta Particles and Low Energy X-Rays' and 'Radiation Damage to the Skin'. It is concluded that protection criteria for the limitation of skin dose are in need of revision. (author)

Radiogenic Isotopes in Weathering and Hydrology

Science.gov (United States)

Blum, J. D.; Erel, Y.

2003-12-01

There are a small group of elements that display variations in their isotopic composition, resulting from radioactive decay within minerals over geological timescales. These isotopic variations provide natural fingerprints of rock-water interactions and have been widely utilized in studies of weathering and hydrology. The isotopic systems that have been applied in such studies are dictated by the limited number of radioactive parent-daughter nuclide pairs with half-lives and isotopic abundances that result in measurable differences in daughter isotope ratios among common rocks and minerals. Prior to their application to studies of weathering and hydrology, each of these isotopic systems was utilized in geochronology and petrology. As in the case of their original introduction into geochronology and petrology, isotopic systems with the highest concentrations of daughter isotopes in common rocks and minerals and systems with the largest observed isotopic variations were introduced first and have made the largest impact on our understanding of weathering and hydrologic processes. Although radiogenic isotopes have helped elucidate many important aspects of weathering and hydrology, it is important to note that in almost every case that will be discussed in this chapter, our fundamental understanding of these topics came from studies of variations in the concentrations of major cations and anions. This chapter is a "tools chapter" and thus it will highlight applications of radiogenic isotopes that have added additional insight into a wide spectrum of research areas that are summarized in almost all of the other chapters of this volume.The first applications of radiogenic isotopes to weathering processes were based on studies that sought to understand the effects of chemical weathering on the geochronology of whole-rock samples and geochronologically important minerals (Goldich and Gast, 1966; Dasch, 1969; Blaxland, 1974; Clauer, 1979, 1981; Clauer et al., 1982); as well

The Nasa space radiation school, an excellent training in radiobiology and space radiation protection

International Nuclear Information System (INIS)

Vogin, G.

2009-01-01

The astronauts have to spend more time in space and the colonization of the moon and Mars are in the cross hairs of international agencies. The cosmic radiation from which we are protected on ground by atmosphere and by the terrestrial magnetosphere (.4 mSv/year according to Who) become really threatening since 20 km altitude, delivering an average radiation dose of a therapeutic kind to astronauts with peaks related to solar events. It is composed in majority of hadrons: protons (85%) and heavy ions (13%), but also photons (2%) of high energy (GeV/n)). the incurred risks are multiple: early ones(cataract, central nervous system damages, whole body irradiation) but especially delayed ones (carcinogenesis). The astronauts radiation protection turns poor and the rate of death risk by cancer returning from a mission on Mars has been estimated at 5%. The Nasa created in 2004 a summer school aiming to awareness young researchers to the space radiobiology specificities. Areas concerned as follow: radioinduced DNA damage and repair, cell cycle, apoptosis, bystander effect, genome instability, neuro degeneration, delayed effects and carcinogenesis in relation with radiation exposure. (N.C.)

Neutron radiobiology. Summary of a workshop

International Nuclear Information System (INIS)

1978-01-01

This report is a summary of a workshop held in June 1977 at Oak Ridge National Laboratory to evaluate the progress of research in the field of neutron radiobiology. The participants reviewed the results of current research and identified unresolved questions and areas of uncertainty. They then defined areas in which additional research should be undertaken, and, finally, they reviewed ways in which results from current and projected research could be applied to inform and influence regulatory decisions

The European Radiobiology Archives (ERA) - Content, structure and use illustrated by an example

International Nuclear Information System (INIS)

Gerber, G. B.; Wick, R. R.; Kellerer, A. M.; Hopewell, J. W.; Di Majo, V.; Dudoignon, N.; Goessner, W.; Stather, J.

2006-01-01

The European Radiobiology Archives (ERA), supported by the European Commission and the European Late Effect Project Group (EULEP), together with the US National Radiobiology Archives (NRA) and the Japanese Radiobiology Archives (JRA) have collected all information still available on long-term animal experiments, including some selected human studies. The archives consist of a database in Microsoft Access, a web site, databases of references and information on the use of the database. At present, the archives contain a description of the exposure conditions, animal strains, etc. from ∼350,000 individuals; data on survival and pathology are available from ∼200,000 individuals. Care has been taken to render pathological diagnoses compatible among different studies and to allow the lumping of pathological diagnoses into more general classes. 'Forms' in Access with an underlying computer code facilitate the use of the database. This paper describes the structure and content of the archives and illustrates an example for a possible analysis of such data. (authors)

Application of microdosimetry to radiobiology

International Nuclear Information System (INIS)

Zaider, M.; Rossi, H.H.

1987-01-01

The application of microdosimetry to radiobiology has frequently been based on the site model, i.e., the concept of a sensitive subcellular volume in which energy concentration determines the biological effect regardless of the nature of ionizing radiations. A later publication extended the treatment as to include the distance model in which lesion formation is assumed to depend on the initial separation of the two component sublesions. This was developed as a theoretical basis for the molecular ion experiment in which the biological effectiveness of pairs of ions is determined as a function of their separation. The results of this experiment made it evident that the effectiveness of single events must be largely determined by energy concentration in volumes having dimensions of less than a tenth of a micrometer. It can not be determined a priori whether this difference is due to a distance-dependent probability of combination between sublesions that are perhaps produced at random locations in a critical region of the cell (the gross sensitive volume, GSV), or whether the interaction probability is constant but the sensitive material is contained in a matrix that is within the GSV but has a complex geometrical shape. The generalized TDRA allows for either condition or their combination. In this paper it will be shown that regardless of the ultimate resolution of this question microdosimetry can retain its predictive role in radiobiology provided measurements are performed in a series of spherical sites (of different dimensions) rather than one single, micrometer-size volume

Principal Physical and Technical Advantages from the Use of Radiogenic Lead as a Coolant of Power Nuclear Reactors

Energy Technology Data Exchange (ETDEWEB)

Kulikov, G.G. [International Science and Technology Center (ISTC), Krasnoproletarskaya ulitsa 32-34, Moscow, 127473 (Russian Federation); Shmelev, A.N.; Apse, V.A. [Moscow Engineering Physics Institute (State University), Kashirskoe shosse 31, Moscow, 115409 (Russian Federation); Artisyuk, V.V. [Obninsk State Technical University of Nuclear Power Engineering, Obninsk, Kaluzhskaya reg. 249040 (Russian Federation)

2009-06-15

Radiogenic lead is a final product of radioactive decay chains in uranium and thorium ores. After a number of alpha- and beta-decays, the starting isotopes {sup 232}Th, {sup 238}U and {sup 235}U are converted into stable lead isotopes: {sup 208}Pb, {sup 206}Pb and {sup 207}Pb, respectively. Radiogenic lead with a large fraction of {sup 208}Pb has unique neutron-physical properties because {sup 208}Pb is a double magic nuclide with closed proton and neutron shells in nucleus. That is why {sup 208}Pb has an extremely low cross-section of thermal neutron capture reaction ({approx}0.5 mb) in comparison with common lead ({approx}175 mb) and graphite ({approx}3.5 mb). In addition, {sup 208}Pb is a weak neutron moderator through inelastic scattering of fast neutrons owing to the higher first energy excitation level of nucleus ({approx}2.7 MeV for {sup 208}Pb as against {approx}0.8 MeV for common lead) and through elastic scattering owing to a high atomic number. So, high {sup 208}Pb content in lead coolant of fast reactor allows a decrease in the unfavorable spectral component in a coolant temperature reactivity coefficient [1]. In spite of {sup 208}Pb content being as high as 52% in common lead, the remaining lead fraction (mainly {sup 207}Pb and {sup 204}Pb isotopes) is characterized both by a large neutron capture cross-section and essential inelastic scattering. Radiogenic lead from thorium and uranium-thorium ores has a very low fraction of these unfavorable isotopes. The use of radiogenic lead as a coolant and graphite as a structural material creates favorable conditions for development of high-temperature and high-flux reactors. Such a high-temperature reactor differs profitably from He-cooled HTGR by low pressure and natural circulation of coolant, while such a high-flux reactor makes it possible to transmute radioactive isotopes with extremely low neutron capture cross-sections, like {sup 90}Sr and {sup 137}Cs. Plutonium in ({sup 238}U-Pu-Th-{sup 233}U

Radiobiology of human cancer radiotherapy

International Nuclear Information System (INIS)

Andrews, J.R.

1978-01-01

The author has systematically collected and collated the scientific literature correlating the basic and clinical sciences in this field in order to produce a definitive treatise. The book thoroughly reviews the biology and biochemistry relevant to radiobiology and describes the critical locus for the extinction of cell reproductive capacity. Extensive coverage is given to oxygen effect, hyperthermia, high linear energy transfer, cell populations, and similar topics. Separate sections cover time, dose, and fractionation; radiation hematology; cancer chemotherapy; and cancer immunology. The book also contains invaluable discussions of techniques for optimizing radiotherapy alone and in combination with other therapies

Can Transport of Saharan Dust Explain Extensive Clay Deposits in the Amazon Basin? A Test Using Radiogenic Isotopes

Science.gov (United States)

Andreae, M. O.; Abouchami, W.; Näthe, K.; Kumar, A.; Galer, S. J.; Jochum, K. P.; Williams, E.; Horbe, A. M.; Rosa, J. W.; Adams, D. K.; Balsam, W. R.

2012-12-01

The Bodélé Depression, located in the Southern Sahara, is a huge source of atmospheric dust and thus an important element in biogeochemical cycles and the radiative budget of Earth's atmosphere. Previous studies have shown that Saharan dust transport across the Atlantic acts as an important source of mineral nutrients to the Amazon rainforest. The Belterra Clay, which outcrops extensively across the Amazon Basin in Brazil, has been proposed to result from dry deposition of African dusts. We have investigated this hypothesis by measuring the radiogenic isotopic composition (Sr, Nd and Pb) of a suite of samples from the Belterra Clay, the Bodélé Depression, dusts deposits collected at various locations along the airmass transport trajectory, as well as loess from the Cape Verde Islands. Radiogenic isotope systems are powerful tracers of provenance and can be used to fingerprint dust sources and atmospheric transport patterns. Our results identify distinct isotopic signatures in the Belterra Clay samples and the African sources. The Belterra Clay display radiogenic Sr and Pb isotope ratios associated with non-radiogenic Nd isotope signatures. In contrast, Bodélé samples and dusts deposits show lower Pb isotope ratios, variable 87Sr/86Sr, and relatively homogeneous Nd isotopic compositions, albeit more radiogenic than those of the Belterra Clay. Our data show unambiguously that the Belterra Clay is not derived from African dust deposition, nor from the Andean chain, as originally suggested by W. Sombroek. Rather, isotopic compositions and Nd model ages are consistent with simple mixing of Archean and younger Proterozoic terranes within the Amazon Basin as a result of weathering and erosion under humid tropical conditions. Whether Saharan dusts contribute to the fertilization in the Amazon Basin cannot be ruled out, however, since the African dust isotopic signature is expected to be entirely overprinted by local sources. Radiogenic isotope data obtained on

Probabilistic causality and radiogenic cancers

International Nuclear Information System (INIS)

Groeer, P.G.

1986-01-01

A review and scrutiny of the literature on probability and probabilistic causality shows that it is possible under certain assumptions to estimate the probability that a certain type of cancer diagnosed in an individual exposed to radiation prior to diagnosis was caused by this exposure. Diagnosis of this causal relationship like diagnosis of any disease - malignant or not - requires always some subjective judgments by the diagnostician. It is, therefore, illusory to believe that tables based on actuarial data can provide objective estimates of the chance that a cancer diagnosed in an individual is radiogenic. It is argued that such tables can only provide a base from which the diagnostician(s) deviate in one direction or the other according to his (their) individual (consensual) judgment. Acceptance of a physician's diagnostic judgment by patients is commonplace. Similar widespread acceptance of expert judgment by claimants in radiation compensation cases does presently not exist. Judicious use of the present radioepidemiological tables prepared by the Working Group of the National Institutes of Health or of updated future versions of similar tables may improve the situation. 20 references

Characterization and performances of DOSION, a dosimetry equipment dedicated to radiobiology experiments taking place at GANIL

Energy Technology Data Exchange (ETDEWEB)

Boissonnat, Guillaume, E-mail: boissonnat@lpccaen.in2p3.fr [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Fontbonne, Jean-Marc [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Balanzat, Emmanuel [CIMAP (CEA/DSM-CNRS/INP-ENSICAEN-UNICAEN), Bd Henri Becquerel, 14076 Caen (France); Boumard, Frederic; Carniol, Benjamin [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Cassimi, Amine [CIMAP (CEA/DSM-CNRS/INP-ENSICAEN-UNICAEN), Bd Henri Becquerel, 14076 Caen (France); Colin, Jean; Cussol, Daniel; Etasse, David; Fontbonne, Cathy [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Frelin, Anne-Marie [GANIL (CEA/DSM-CNRS/IN2P3), Bd Henri Becquerel, 14076 Caen (France); Hommet, Jean; Salvador, Samuel [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France)

2017-06-01

Currently, radiobiology experiments using heavy ions at GANIL (Grand Accélérateur National d′Ions Lourds) are conducted under the supervision of the CIMAP (Center for research on Ions, MAterials and Photonics). In this context, a new beam monitoring equipment named DOSION has been developed. It allows to perform measurements of accurate fluence and dose maps in near real time for each biological sample irradiated. In this paper, we present the detection system, its design, performances, calibration protocol and measurements performed during radiobiology experiments. This setup is currently available for any radiobiology experiments if one wishes to correlate one's own sample analysis to state-of-the-art dosimetric references.

Radiobiological researches on Dianthus caryophyllus L. carnation chimeras

International Nuclear Information System (INIS)

Pereau-Leroy, Pierre

1975-01-01

This research thesis reports a radiobiological study of Dianthus periclinal chimeras performed by submitting plants and plant cuttings at different physiological stages to cobalt-60 gamma irradiation under different dose conditions and rates. The effects of these treatments are studied while growing the so-processed plants and by microscopic examination of sections of irradiated meristems [fr

Tritium radiobiology research in the US DOE program

International Nuclear Information System (INIS)

Carsten, A.L.

1986-01-01

The history of the original US Atomic Energy Commission, its replacement, the Energy Research and Development Administration, and the present Department of Energy's interest and sponsorship of tritium radiobiology is reviewed beginning in 1971 and continuing through 1986. In particular, the four remaining US Department of Energy, Division of Health and Environmental Research programs are described in some detail

Research in radiobiology. Annual report, Internal Irradiation Program

International Nuclear Information System (INIS)

Miller, S.C.; Buster, D.S.

1985-01-01

The annual progress report for the Radiobiology Division of the University of Utah College of Medicine is presented. Summaries of twenty-four projects concerning the metabolism, dosimetry and toxicity of a variety of actinide elements in beagles or rats are given. Individual papers within this report have been separately indexed and abstracted for the data base

What kind of radiobiology should be done at a hadron therapy center

International Nuclear Information System (INIS)

Kraft, G.; Kraft-Weyrather, W.; Taucher-Scholz, G.; Scholz, M.

1997-01-01

Although therapy with heavy particles like neutrons, protons or heavier ions has now a rather long history of several decades, but there are more open questions than settled problems. This fact is really amazing because the use of the high LET particles, neutrons and heavy ions was strongly motivated by radiobiological arguments. Presently, the use of protons with a better physical dose distribution is more widely accepted than neutrons or heavy ions where the expected high LET benefit could not be verified clinically. This demonstrates that predictions made on the basis of radiobiological experiments cannot be transferred directly from in vitro experiments to the therapy situation. In particular, it is not possible to transfer an average RBE value measured in vitro in an extended exposure field to the treatment situation. Therefore, in the following section the dependence of RBE on LET, dose and radiosensitivity will be summarized and compared to models. Basic experiments illustrating the RBE problem in a particle field will be described. The fundamentals of a recently developed track structure model will be given and calculations will be compared to experiments. Finally, a short outline of possible future developments for radiobiology will be presented. (orig.)

Radiobiology and dosimetry

International Nuclear Information System (INIS)

Saenger, E.L.; Kereiakes, J.G.

1975-01-01

A brief review of radiobiology is presented that should indicate the reasonable limits of pediatric nuclear medicine. Together with the dosimetric information and the few caveats of laboratory procedure, the use of nuclear medicine as clinically indicated, maintaining doses as low as practicable, should be readily applied to pediatrics. In discussing benefits versus risks in nuclear medicine, the conscience guide (CG) was introduced as a unit, being defined as the referral rate to better qualified centers from a laboratory where expertise in a given test is lacking versus the total number of examinations done in that laboratory. When considering procedures in the pediatric age group, the physician is urged to use the CG to do only those procedures for which he and his staff have adequate equipment and experience. In this way, the best interests of the patient and physician can be insured. (auth)

Radiobiological compensation: A case study of uterine cervix cancer with concurrent chemotherapy

Energy Technology Data Exchange (ETDEWEB)

Herrera, Higmar; Yanez, Elvia; Lopez, Jesus [Centro Estatal de Cancerologia de Durango, Victoria de Durango, Durango (Mexico); ISSSTE General Hospital Dr. Santiago Ramon y Cajal, Victoria de Durango, Durango (Mexico)

2012-10-23

The case of a patient diagnosed with uterine cervix cancer is presented as an example of the clinical application of the radiobiological compensation method implemented at Centro Estatal de Cancerologia de Durango. Radiotherapy treatment was initially modified to compensate for the chemotherapy component and, as medical complications arose during treatment delivery resulting in an 18 days gap, new compensation followed. All physical and radiobiological assumptions to calculate the Biologically Effective Dose in the external beam and brachytherapy parts of the treatment are presented. Good local control of the tumor was achieved, the theoretical tolerance limits for the organs at risk were not surpassed and the patient manifested no extensive morbidity.

DNA Damage and Repair in Plants under Ultraviolet and Ionizing Radiations

Science.gov (United States)

Gill, Sarvajeet S.; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315–400 nm; UV-B, 280–315 nm; and UV-C, important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH•) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context. PMID:25729769

On the radiogenic heat production of igneous rocks

Directory of Open Access Journals (Sweden)

D. Hasterok

2017-09-01

Full Text Available Radiogenic heat production is a physical parameter crucial to properly estimating lithospheric temperatures and properly understanding processes related to the thermal evolution of the Earth. Yet heat production is, in general, poorly constrained by direct observation because the key radiogenic elements exist in trace amounts making them difficulty image geophysically. In this study, we advance our knowledge of heat production throughout the lithosphere by analyzing chemical analyses of 108,103 igneous rocks provided by a number of geochemical databases. We produce global estimates of the average and natural range for igneous rocks using common chemical classification systems. Heat production increases as a function of increasing felsic and alkali content with similar values for analogous plutonic and volcanic rocks. The logarithm of median heat production is negatively correlated (r2 = 0.98 to compositionally-based estimates of seismic velocities between 6.0 and 7.4 km s−1, consistent with the vast majority of igneous rock compositions. Compositional variations for continent-wide models are also well-described by a log-linear correlation between heat production and seismic velocity. However, there are differences between the log-linear models for North America and Australia, that are consistent with interpretations from previous studies that suggest above average heat production across much of Australia. Similar log-linear models also perform well within individual geological provinces with ∼1000 samples. This correlation raises the prospect that this empirical method can be used to estimate average heat production and natural variance both laterally and vertically throughout the lithosphere. This correlative relationship occurs despite a direct causal relationship between these two parameters but probably arises from the process of differentiation through melting and crystallization.

Radiogenic lead with dominant content of {sup 208}Pb: New coolant and neutron moderator for innovative nuclear reactors

Energy Technology Data Exchange (ETDEWEB)

Shmelev, A. N.; Kulikov, G. G.; Kryuchkov, E. F.; Apse, V. A.; Kulikov, E. G. [National Research Nuclear Univ. MEPhI, Kashirskoe shosse, 31, 115409, Moscow (Russian Federation)

2012-07-01

The advantages of radiogenic lead with dominant content of {sup 208}Pb as a reactor coolant with respect to natural lead are caused by unique nuclear properties of {sup 208}Pb which is a double-magic nucleus with closed proton and neutron shells. This results in significantly lower micro cross section and resonance integral of radiative neutron capture by {sup 208}Pb than those for numerous light neutron moderators. The extremely weak ability of {sup 208}Pb to absorb neutrons results in the following effects. Firstly, neutron moderating factor (ratio of scattering to capture cross sections) is larger than that for graphite and light water. Secondly, age and diffusion length of thermal neutrons are larger than those for graphite, light and heavy water. Thirdly, neutron lifetime in {sup 208}Pb is comparable with that for graphite, beryllium and heavy water what could be important for safe reactor operation. The paper presents some results obtained in neutronics and thermal-hydraulics evaluations of the benefits from the use of radiogenic lead with dominant content of {sup 208}Pb instead of natural lead as a coolant of fast breeder reactors. The paper demonstrates that substitution of radiogenic lead for natural lead can offer the following benefits for operation of fast breeder reactors. Firstly, improvement of the reactor safety thanks to the better values of coolant temperature reactivity coefficient and, secondly, improvement of some thermal-hydraulic reactor parameters. Radiogenic lead can be extracted from thorium sludge without isotope separation as {sup 208}Pb is a final isotope in the decay chain of {sup 232}Th. (authors)

In vivo tumor radiobiology of heavy charged particles

International Nuclear Information System (INIS)

Curtis, S.B.; Tenforde, T.S.

1980-01-01

The response of tumor cells systems to irradiation with carbon, neon and argon beams at various positions in the plateau and extended-peak regions of the Bragg ionization curve is being evaluated from experiments conducted both in vivo and in vitro. The radiobiological end points being studied include: tumor volume response, cellular survival after tumor irradiation in situ, and cell-kinetic parameters

National Radiobiology Archives Distributed Access user's manual

Energy Technology Data Exchange (ETDEWEB)

Watson, C.; Smith, S. (Pacific Northwest Lab., Richland, WA (United States)); Prather, J. (Linfield Coll., McMinnville, OR (United States))

1991-11-01

This User's Manual describes installation and use of the National Radiobiology Archives (NRA) Distributed Access package. The package consists of a distributed subset of information representative of the NRA databases and database access software which provide an introduction to the scope and style of the NRA Information Systems.

Radiobiological research needed for the improvement of radiotherapy

International Nuclear Information System (INIS)

1977-01-01

The use of radiation in therapy of cancer and diagnosis of other diseases has been practised since the discovery of X-ray. Radiotherapy of cancer was founded on the simple observation that radiations can kill tumour cells. As the science of radiobiology developed, some of its concepts were slowly incorporated in the therapeutic use of radiations, and this led to improve patient treatment. However, although radiobiology continued to progress, a communication gap built up between practising clinicians and radiobiologists. The purpose of this symposium was to help bridge the gap and to encourage co-operation between radiotherapists and radiobiologists. Fractionated dose regimes for external cobalt or X-ray therapy were extensively discussed. Of particular concern was whether acute dose rates which could reduce treatment time per patient would be favourable from the point of view of side effects on normal tissues such as skin, spinal cord, lungs, kidneys and other organs. Also discussed was whether high doses followed by small dose fractionation would lead to a therapeutic gain. New information was presented that during the fractionation period, normal cells may have better recovery potential than the tumour cells, and in view of this new information, the present practice of radiotherapy using fractionated doses may be further improved. The failures of radiotherapy are mainly due to the radioresistant hypoxic cells which escape radiation damage. These could be destroyed with the use of high LET radiations, super fractionated dose schedules or radiosensitisers specifically active towards hypoxic cells. Chemical radiosensitisers have now become available and have proved as effective as neutrons in their therapeutic gains. Clinical trials are underway in the UK and Romania on these radiosensitisers. One that deserves special mention is a nitroimidazole derivative, RO-07-0582, which has had extensive in vitro and in vivo studies, and clinical trials with human patients

Radiation monitoring considerations for radiobiology facilities

International Nuclear Information System (INIS)

McClelland, T.W.; McFall, E.D.

1976-01-01

Battelle, Pacific Northwest Laboratories, conducts a wide variety of radiobiology and radioecology research in a number of facilities on the Hanford Reservation. Review of radiation monitoring problems associated with storage, plant and animal experiments, waste handling and sterile facilities shows that careful monitoring, strict procedural controls and innovative techniques are required to minimize occupational exposure and control contamination. Although a wide variety of radioactivity levels are involved, much of the work is with extremely low level materials. Monitoring low level work is mundane and often impractical but cannot be ignored in today's ever tightening controls

Physics and radiobiology of nuclear medicine

CERN Document Server

Saha, Gopal B

2010-01-01

From a distinguished author comes this new edition for technologists, practitioners, residents, and students in radiology and nuclear medicine. Encompassing major topics in nuclear medicine from the basic physics of radioactive decay to instrumentation and radiobiology, it is an ideal review for Board and Registry examinations. The material is well organized and written with clarity. The book is supplemented with tables and illustrations throughout. It provides a quick reference book that is concise but comprehensive, and offers a complete discussion of topics for the nuclear medicine and radi

SU-F-T-03: Radiobiological Evaluation of a Directional Brachytherapy Device Surgically Implanted Following EBRT

Energy Technology Data Exchange (ETDEWEB)

Rivard, MJ [Tufts University School of Medicine, Boston, MA (United States); Emrich, JG; Poli, J [Drexel University College of Medicine, Philadelphia, PA (United States)

2016-06-15

Purpose: Preceding surgical implantation following external-beam radiotherapy (EBRT) delivery, a radiobiological evaluation was performed for a new LDR Pd-103 directional brachytherapy device (CivaSheet). As this was the first case with the device used in combination with EBRT, there was concern to determine the appropriate prescription dose. Methods: The radiobiological model of Dale (1985, 1989) was used for a permanent LDR implant including radioactive decay. The biological effective dose (BED) was converted to the equivalent dose in 2 Gy fractions (EQD2) for comparison with EBRT prescription expectations. Given IMRT delivery of 50.4 Gy, an LDR brachytherapy dose of approximately 15–20 Gy EQD2 was desired. To be specific to the treatment site (leiomyosarcoma T2bN0M0, grade 2 with R1 surgical margin), the radiobiological model required several radiobiological parameters with values taken from the literature. A sensitivity analysis was performed to determine their relative importance on the calculated BED and subsequent EQD2. The Pd-103 decay constant (λ=0.0017 h{sup −1}) was also used. DVHs were prepared for pre- and post-surgical geometries to glean the possible and realized implant geometric configuration. DVHs prepared in VariSeed9 were converted to BEDVHs and subsequently EQD2 values for each volume-element. Results: For a physical dose of 28 Gy to a 0.5 cm depth, BED=21.7 Gy and EQD2=17.6 Gy, which was near the center of the desired EQD2 range. Tumor bed (CTV=4 cm{sup 3}) coverage was 99.2% with 48 sources implanted. In order of decreasing importance from the sensitivity analysis, the radiobiological parameters were α=0.25 Gy{sup −1}, T{sub POT}=23 days, α/β=8.6 Gy, and T=1.5 h. Percentage variations in these values produced EQD2 variations of 40%, 20%, 18%, and 1%, respectively. Conclusion: This radiobiological evaluation indicated that prescription dose may be determined for comparison with the desired EQD2, and that radiobiologicalparameter

Radiobiological compensation: A case study of uterine cervix cancer with concurrent chemotherapy

International Nuclear Information System (INIS)

Herrera, Higmar; Yañez, Elvia; López, Jesús

2012-01-01

The case of a patient diagnosed with uterine cervix cancer is presented as an example of the clinical application of the radiobiological compensation method implemented at Centro Estatal de Cancerología de Durango. Radiotherapy treatment was initially modified to compensate for the chemotherapy component and, as medical complications arose during treatment delivery resulting in an 18 days gap, new compensation followed. All physical and radiobiological assumptions to calculate the Biologically Effective Dose in the external beam and brachytherapy parts of the treatment are presented. Good local control of the tumor was achieved, the theoretical tolerance limits for the organs at risk were not surpassed and the patient manifested no extensive morbidity.

Radiobiological compensation: A case study of uterine cervix cancer with concurrent chemotherapy

Science.gov (United States)

Herrera, Higmar; Yañez, Elvia; López, Jesús

2012-10-01

The case of a patient diagnosed with uterine cervix cancer is presented as an example of the clinical application of the radiobiological compensation method implemented at Centro Estatal de Cancerología de Durango. Radiotherapy treatment was initially modified to compensate for the chemotherapy component and, as medical complications arose during treatment delivery resulting in an 18 days gap, new compensation followed. All physical and radiobiological assumptions to calculate the Biologically Effective Dose in the external beam and brachytherapy parts of the treatment are presented. Good local control of the tumor was achieved, the theoretical tolerance limits for the organs at risk were not surpassed and the patient manifested no extensive morbidity.

The status and role of radiobiology in veterinary medicine

International Nuclear Information System (INIS)

Benova, K.

2007-01-01

In this presentation author deals with history of the University of Veterinary Medicine in Kosice as well as with the status and role of radiobiology in veterinary medicine. Some results of gamma irradiation of Pecilia reticulata are presented. Activity levels of cesium-137 in contaminated mushrooms gathered in Slovakia in 2001 are presented.

Scientific projection paper for space radiobiological research

International Nuclear Information System (INIS)

Vinograd, S.P.

1980-01-01

A nationale for the radiobiological research requirements for space is rooted in a national commitment to the exploration of space, mandated in the form of the National Space Act. This research is almost entirely centered on man; more specifically, on the effects of the space radiation environment on man and his protection from them. The research needs discussed in this presentation include the space radiation environment; dosimetry; radiation biology-high LET particles (dose/response); and operational countermeasures

The use of recombinant DNA techniques to study radiation-induced damage, repair and genetic change in mammalian cells

International Nuclear Information System (INIS)

Thacker, J.

1986-01-01

A brief introduction is given to appropriate elements of recombinant DNA techniques and applications to problems in radiobiology are reviewed with illustrative detail. Examples are included of studies with both 254 nm ultraviolet light and ionizing radiation and the review progresses from the molecular analysis of DNA damage in vitro through to the nature of consequent cellular responses. The review is dealt with under the following headings: Molecular distribution of DNA damage, The use of DNA-mediated gene transfer to assess damage and repair, The DNA double strand break: use of restriction endonucleases to model radiation damage, Identification and cloning of DNA repair genes, Analysis of radiation-induced genetic change. (UK)

Radiobiological analyse based on cell cluster models

International Nuclear Information System (INIS)

Lin Hui; Jing Jia; Meng Damin; Xu Yuanying; Xu Liangfeng

2010-01-01

The influence of cell cluster dimension on EUD and TCP for targeted radionuclide therapy was studied using the radiobiological method. The radiobiological features of tumor with activity-lack in core were evaluated and analyzed by associating EUD, TCP and SF.The results show that EUD will increase with the increase of tumor dimension under the activity homogeneous distribution. If the extra-cellular activity was taken into consideration, the EUD will increase 47%. Under the activity-lack in tumor center and the requirement of TCP=0.90, the α cross-fire influence of 211 At could make up the maximum(48 μm)3 activity-lack for Nucleus source, but(72 μm)3 for Cytoplasm, Cell Surface, Cell and Voxel sources. In clinic,the physician could prefer the suggested dose of Cell Surface source in case of the future of local tumor control for under-dose. Generally TCP could well exhibit the effect difference between under-dose and due-dose, but not between due-dose and over-dose, which makes TCP more suitable for the therapy plan choice. EUD could well exhibit the difference between different models and activity distributions,which makes it more suitable for the research work. When the user uses EUD to study the influence of activity inhomogeneous distribution, one should keep the consistency of the configuration and volume of the former and the latter models. (authors)

BNL ACCELERATOR-BASED RADIOBIOLOGY FACILITIES

International Nuclear Information System (INIS)

LOWENSTEIN, D.I.

2000-01-01

For the past several years, the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (USA) has provided ions of iron, silicon and gold, at energies from 600 MeV/nucleon to 10 GeV/nucleon, for the US National Aeronautics and Space Administration (NASA) radiobiology research program. NASA has recently funded the construction of a new dedicated ion facility, the Booster Applications Facility (BAF). The Booster synchrotron will supply ion beams ranging from protons to gold, in an energy range from 40--3,000 MeV/nucleon with maximum beam intensities of 10 10 to 10 11 ions per pulse. The BAF Project is described and the future AGS and BAF operation plans are presented

Radiobiology Department. Report of Activities 1977-1980

International Nuclear Information System (INIS)

1982-02-01

The different research activities carried out by the Radiobiology Department of the CNEA over the 4-year period 1977-1980 are summarized. These activities were devoted to the study of the effects of radiation on different biological systems, to the search for adequate experimental models, and to the development of techniques permiting a correct evaluation of the information obtained. Topics covered are genetics, microbiology, somatic effects of radiation, pathology and the operation of the animal's house. (M.E.L.) [es

Biometrical analysis in radiobiological works of N.V. Luchnik

International Nuclear Information System (INIS)

Glotov, N.V.

1996-01-01

The contribution of the famous Russian geneticist and biophysics N.V. Luchnik into biometrical analysis of radiobiological data is discussed. His works on radiation mortality of mice (2) and the process of post-radiation repair of chromosome aberrations (10) are thoroughly observed. The conclusion of necessity to develop biometrical analysis as separate part of biometry is made

Radiogenic lead-208 abundance 88.34 %

International Nuclear Information System (INIS)

Seneda, Jose A.; Abrao, Alcidio; Dias, Mauro S.; Kakazu, Mauricio H.; Salvador, Vera L.R.; Queiroz, Carlos A.S.; Rocha, Soraya M.R. da; Sato, Key

2009-01-01

Brazil has a long tradition in thorium technology, from the monazite ores mining until the production of the nuclear grade thorium compounds. Early in 1969 the Institute of Energy and Nuclear Research (IPEN) designed a project for a pilot plant installation to purify the thorium compounds, based on the solvent extraction technique. Thorium compounds used came from monazite's industrialization. During the course of the operation of this plant, a crude sludge were formed containing thorium not extracted and the whole rare earths, plus minor impurities like sodium, titanium, zirconium, hafnium, iron, silicon, phosphate and the thorium daughters were accumulated. Included is the radiogenic lead-208. This sludge, hereafter named 'RETOTER', was treated with hydrochloric acid and the lead was separated and recovered by anion exchange technology. The lead-208 was analyzed by mass spectrometry (HR-ICPMS) technique. The lead-208 abundance measure was 88.34%, this allowed the calculation of the thermal neutron capture cross section of σ 0 γ = 14,6 +/- 0.7 mb, considerably lower than the σ 0 γ = 174.2 +/- 0.7 mb value of the natural lead. (author)

Heat flow study at the Chinese Continental Scientific Drilling site: Borehole temperature, thermal conductivity, and radiogenic heat production

Science.gov (United States)

He, Lijuan; Hu, Shengbiao; Huang, Shaopeng; Yang, Wencai; Wang, Jiyang; Yuan, Yusong; Yang, Shuchun

2008-02-01

The Chinese Continental Scientific Drilling (CCSD) Project offers a unique opportunity for studying the thermal regime of the Dabie-Sulu ultrahigh-pressure metamorphic belt. In this paper, we report measurements of borehole temperature, thermal conductivity, and radiogenic heat production from the 5158 m deep main hole (CCSD MH). We have obtained six continuous temperature profiles from this borehole so far. The temperature logs show a transient mean thermal gradient that has increased from 24.38 to 25.28 K km-1 over a period of about 1.5 years. We measured thermal conductivities and radiogenic heat productions on more than 400 core samples from CCSD MH. The measured thermal conductivities range between 1.71 and 3.60 W m-1 K-1, and the radiogenic heat productions vary from 0.01 μW m-3 to over 5.0 μW m-3, with a mean value of 1.23 ± 0.82 μW m-3 for the upper 5-km layer of the crust. The heat productions in CCSD MH appear to be more rock-type than depth-dependent and, over the depth range of CCSD MH, do not fit the popular model of heat production decreasing exponentially with increasing depth. The measured heat flow decreases with depth from ˜75 mW m-2 near the surface to ˜66 mW m-2 at a depth of 4600 m. High heat flow anomalies occur at ˜1000 and ˜2300 m, and low anomalies occur at 3300-4000 m. A preliminary two-dimensional numerical model suggests that both radiogenic heat production and thermal refraction due to structural heterogeneity are at least partially responsible for the vertical variation of heat flow in CCSD MH.

Radiogenic age and isotopic studies

International Nuclear Information System (INIS)

Parrish, R.R.

1990-01-01

This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Reports in this issue cover methods for Rb-Sr and Sm-Nd isotopic analyses; 40 Ar- 39 Ar ages for the New Quebec Crater and for basaltic rocks; U-Pb ages for a differentiated mafic sill in the Ogilvie Mountains, plutonic rocks in the Contwoyto-Nose Lakes are, zircons from the Anton Complex, the Clinton-Colden gabbro-anorthosite intrusion, the Himag plutonic suite, the Campbell granite, the Central Gneiss Belt, Silurian granites, a metarhyolite, plagiogranite and gabbro, and the Wage shear zone; Rb-Sr ages for granitic rocks; K-Ar and Rb-Sr geochronology of granites; a compilation of K-Ar ages; ages of archean and proterozoic mylonites and pre-Misi granitoid domes; and reconnaissance geochronology of Baffin Island

Radiobiology of normal tissue. Scientific advances and perspectives; Strahlenbiologie der Normalgewebe. Wissenschaftliche Fortschritte und Perspektiven

Energy Technology Data Exchange (ETDEWEB)

Doerr, W. [Medizinische Univ. Wien (Austria). Universitaetsklinik fuer Strahlentherapie; Medizinische Univ. Wien (Austria). Universitaetsklinik fuer Radioonkologie; Medizinische Univ. Wien (Austria). Christian Doppler Labor fuer Medizinische Strahlenforschung fuer die Radioonkologie; Herskind, C. [Universitaetsmedizin Mannheim, Heidelberg Univ., Mannheim (Germany). Labor fuer Zellulaere und Molekulare Radioonkologie

2012-11-15

Radiotherapy involves always the exposure of normal tissue, resulting in an excepted risk of complications. The side effect rate is therefore the compromise between optimized tumor doses and the side effect minimization. The report covers the issues target cell hypothesis and the consequences, new aspect of the pathogenesis of normal issue reactions and strategies of targeted reduction of normal tissue effects. The complexity of the radiobiological processes, the specificity and action mechanisms, the mutual interactions of chemical and radiological processes require further coordinated radiobiological research in the future.

Clinical peculiarities of the brain damage in the liquidators of the Chernobyl accident

Energy Technology Data Exchange (ETDEWEB)

Zozulya, Y A; Vinnitsky, A R; Stepanenko, I V [Institute of Neurosurgery, Academy of Medical Sciences, Kiev (Ukraine)

1997-09-01

Investigation into the features of the brain damage by the liquidators of the Chernobyl accident has become an urgent issue of today due to a number of circumstances. According to the classical concept dominating radiobiology until recently, the brain being composed of highly - differentiated nerve cells, present a radioresistant structure responsive to radiation injury induced by high and very high radiation doses (10000 rem and higher) only. The results of clinical examinations given to the Chernobyl accident recovery workers at Kiev Institute of Neurosurgery, Academy of Medical Sciences of Ukraine, show that even the so - called ``small - dose`` radiation, when consumed continuously, produces neurological sings of brain damage. 6 figs.

Clinical peculiarities of the brain damage in the liquidators of the Chernobyl accident

International Nuclear Information System (INIS)

Zozulya, Y.A.; Vinnitsky, A.R.; Stepanenko, I.V.

1997-01-01

Investigation into the features of the brain damage by the liquidators of the Chernobyl accident has become an urgent issue of today due to a number of circumstances. According to the classical concept dominating radiobiology until recently, the brain being composed of highly - differentiated nerve cells, present a radioresistant structure responsive to radiation injury induced by high and very high radiation doses (10000 rem and higher) only. The results of clinical examinations given to the Chernobyl accident recovery workers at Kiev Institute of Neurosurgery, Academy of Medical Sciences of Ukraine, show that even the so - called ''small - dose'' radiation, when consumed continuously, produces neurological sings of brain damage. 6 figs

Tracking seasonal subglacial drainage evolution of alpine glaciers using radiogenic Nd and Sr isotope systematics: Lemon Creek Glacier, Alaska

Science.gov (United States)

Clinger, A. E.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

2014-12-01

The transport pathways of water beneath a glacier are subject to change as melt seasons progress due to variability in the balance between basal water pressure and water flux. Subglacial hydrology has been well studied, but the understanding of spatial distribution is less well constrained. Whereas radiogenic isotopic tracers have been traditionally used as proxies to track spatial variability and weathering rates in fluvial and riverine systems, these techniques have yet to be applied extensively to the subglacial environment and may help resolve ambiguity in subglacial hydrology. Research has shown the 143Nd/144Nd values can reflect variation in source provenance processes due to variations in the age of the continental crust. Correlating the 143Nd/144Nd with other radiogenic isotope systematics such as strontium (87Sr/86Sr) provides important constraints on the role of congruent and incongruent weathering processes. Our study presents the application of Nd and Sr systematics using isotopic ratios to the suspended load of subglacial meltwater collected over a single melt season at Lemon Creek Glacier, USA (LCG). The time-series data show an average ɛNd ~ -6.83, indicating a young bedrock (~60 MYA). Isotopic variation helps track the seasonal expansion of the subglacial meltwater channels and subsequent return to early season conditions due to the parabolic trend towards less radiogenic Nd in June and towards more radiogenic Nd beginning in mid-August. However, the high variability in July and early August may reflect a mixture of source as the channels diverge and derive sediment from differently aged lithologies. We find a poor correlation between 143Nd/144Nd and 87Sr/86Sr (R2= 0.38) along with a slight trend towards more radiogenic 87Sr/86Sr values with time ((R2= 0.49). This may indicate that, even as the residence time decreases over the melt season, the LCG subglacial system is relatively stable and that the bedrock is congruently weathered. Our study

An automated method for breathing frequency determination for rat lung radiobiology in BNCT

International Nuclear Information System (INIS)

Kiger, J.L.; Coderre, J.A.; Kiger, W.S. III

2006-01-01

Whole-body plethysmography was used to the measure the breathing rate in rats as a functional indication of radiation-induced lung damage, either weekly or bi-weekly for a period of 180 days following thorax irradiations in a BNCT radiobiology study. A three-minute digital breathing signal was collected in each measurement. Software has been developed to automatically discriminate against large-amplitude noise due to animal movement. After segmenting the signal into consecutive, overlapping and circular blocks, the mean frequency spectrum of the processed signal was calculated using the Fast Fourier Transform (FFT). The breathing rate was defined as the primary frequency of the spectrum and the standard deviation was estimated using the bootstrap method. The mean standard deviation of all measurements in the data set (n=4269) was 2.4%. The improved accuracy with low standard deviation of the measurements ensures good sensitivity and a low threshold for detection of responding animals; breathing rates more than 20% (∼3 σ) above the control mean were considered responding. (author)

Epidemiological and radio-biological studies in high background radiation areas of Kerala coast: implications in radiation protection science and human health

International Nuclear Information System (INIS)

Das, Birajalaxmi

2018-01-01

Till date, Linear No Threshold hypothesis (LNT) is well accepted in radiation protection science in spite of its limitations. However, dose response studies using multiple biological end points from high-background radiation areas have challenged the linearity. Radio-biological and epidemiological studies from high level natural radiation areas of Kerala coast showed non-linearity as well as efficient repair of DNA damage in HLNRA indicating that dose limits for public exposure needs to be revisited which may have implications in radiation protection science, human health and low dose radiation biology. However, further studies using high throughput approach is required to identify chronic radiation signatures in human population exposed to elevated level of natural background radiation

Development of fast neutron therapy worldwide. Radiobiological, clinical and technical aspects

International Nuclear Information System (INIS)

Wambersie, A.; Richard, F.; Breteau, N.

1994-01-01

Radiobiological data indicate that fast neutrons could bring a benefit in the treatment of some tumour types, and suggest mechanisms through which this benefit could be achieved. However, radiobiology also clearly indicates that there is a need for patient selection as well as for a high-physical selectivity. The main difficulty when interpreting the results of neutron therapy are the poor technical conditions in which the first treatments were applied. This explains why the value and the place of neutron therapy are not universally recognized, although more than 15000 patients have been treated so far worldwide. There are, however, clinical indications of fast neutrons bringing a benefit for the following tumour sites: salivary glands, paranasal sinuses, soft tissue sarcomas, prostatic adenocarcinomas, palliative treatment of melanoma and rectum. These tumours represent about 10-15% of all patients currently referred to the radiation therapy departments. (orig.)

The effect of higher order chromatin structure on DNA damage and repair

International Nuclear Information System (INIS)

Yasui, L.S.; Warters, R.L.; Higashikubo, R.

1985-01-01

Alterations in chromatin structure are thought to play an important role in various radiobiological end points, i.e., DNA damage, DNA damage repair and cell survival. The authors use here the isoleucine deprivation technique to decondense higher order chromatin structure and asses X-ray induced DNA damage, DNA damage repair and cell survival on cells with decondensed chromatin as compared to controls. This chromatin decondensation manifests itself as a 30 fold decrease in nuclear area occupied by heterochromatin, an increased rate of Micrococcal nuclease digestion, 15% increased ethidium bromide intercalation and an altered binding capacity of Hl histone. These chromatin/nuclear changes do not affect X-ray induced DNA damage as measured by the alkaline elution technique or cell survival but slows DNA damage repair by 2 fold. Therefore, even though the chromatin appears more accessible to DNA damage and repair processes, these particular nuclear changes do not affect the DNA damaging effects of X-rays and in addition, repair is not enhanced by the ''relaxed'' state of chromatin. It is proposed that the altered metabolic state of isoleucine deprived cells provides a less efficient system for the repair of X-ray induced DNA damage

Dynamical modeling approach to risk assessment for radiogenic leukemia among astronauts engaged in interplanetary space missions.

Science.gov (United States)

Smirnova, Olga A; Cucinotta, Francis A

2018-02-01

A recently developed biologically motivated dynamical model of the assessment of the excess relative risk (ERR) for radiogenic leukemia among acutely/continuously irradiated humans (Smirnova, 2015, 2017) is applied to estimate the ERR for radiogenic leukemia among astronauts engaged in long-term interplanetary space missions. Numerous scenarios of space radiation exposure during space missions are used in the modeling studies. The dependence of the ERR for leukemia among astronauts on several mission parameters including the dose equivalent rates of galactic cosmic rays (GCR) and large solar particle events (SPEs), the number of large SPEs, the time interval between SPEs, mission duration, the degree of astronaut's additional shielding during SPEs, the degree of their additional 12-hour's daily shielding, as well as the total mission dose equivalent, is examined. The results of the estimation of ERR for radiogenic leukemia among astronauts, which are obtained in the framework of the developed dynamical model for various scenarios of space radiation exposure, are compared with the corresponding results, computed by the commonly used linear model. It is revealed that the developed dynamical model along with the linear model can be applied to estimate ERR for radiogenic leukemia among astronauts engaged in long-term interplanetary space missions in the range of applicability of the latter. In turn, the developed dynamical model is capable of predicting the ERR for leukemia among astronauts for the irradiation regimes beyond the applicability range of the linear model in emergency cases. As a supplement to the estimations of cancer incidence and death (REIC and REID) (Cucinotta et al., 2013, 2017), the developed dynamical model for the assessment of the ERR for leukemia can be employed on the pre-mission design phase for, e.g., the optimization of the regimes of astronaut's additional shielding in the course of interplanetary space missions. The developed model can

Numerical analysis of temperature distribution due to basement radiogenic heat production, St. Lawrence Lowlands, eastern Canada

Science.gov (United States)

Liu, Hejuan; Giroux, Bernard; Harris, Lyal B.; Mansour, John

2017-04-01

Although eastern Canada is considered as having a low potential for high-temperature geothermal resources, the possibility for additional localized radioactive heat sources in Mesoproterozoic Grenvillian basement to parts of the Palaeozoic St. Lawrence Lowlands in Quebec, Canada, suggests that this potential should be reassessed. However, such a task remains hard to achieve due to scarcity of heat flow data and ambiguity about the nature of the basement. To get an appraisal, the impact of radiogenic heat production for different Grenville Province crystalline basement units on temperature distribution at depth was simulated using the Underworld Geothermal numerical modelling code. The region south of Trois-Rivières was selected as representative for the St. Lawrence Lowlands. An existing 3D geological model based on well log data, seismic profiles and surface geology was used to build a catalogue of plausible thermal models. Statistical analyses of radiogenic element (U, Th, K) concentrations from neighbouring outcropping Grenville domains indicate that the radiogenic heat production of rocks in the modelled region is in the range of 0.34-3.24 μW/m3, with variations in the range of 0.94-5.83 μW/m3 for the Portneuf-Mauricie (PM) Domain, 0.02-4.13 μW/m3 for the Shawinigan Domain (Morin Terrane), and 0.34-1.96 μW/m3 for the Parc des Laurentides (PDL) Domain. Various scenarios considering basement characteristics similar to the PM domain, Morin Terrane and PDL Domain were modelled. The results show that the temperature difference between the scenarios can be as much as 12 °C at a depth of 5 km. The results also show that the temperature distribution is strongly affected by both the concentration of radiogenic elements and the thermal conductivity of the basement rocks. The thermal conductivity in the basement affects the trend of temperature change between two different geological units, and the spatial extent of thermal anomalies. The validity of the results was

Potassium, uranium, thorium radiogenic heat contribution to heat flow in the Precambrian and younger silicic rocks of the Zuni and Florida Mountains, New Mexico (U.S.A.)

International Nuclear Information System (INIS)

Brookins, D.G.

1982-01-01

High heat flow in the Zuni Mountains, New Mexico, U.S.A., has been explained by the possible presence of a buried felsic pluton. Alternately, high K, U, Th abundances have been proposed to account for part of the high heat flow. The mean radiogenic heat contricution for 60 samples of Precambrian core rocks is 7.23 μcal/gm-yr, which is slightly higher than the average for western U.S.A. granitic rocks and significantly higher than the average for continental 'crust'; hence, the K, U, Th radiogenic contribution from Precambrian rocks to the overall heat flow is significant. Radiogenic K, U, Th heat for 32 samples for the Florida Mountains, New Mexico, U.S.A., yields a lower mean of 5.46 μcal/gm-yr. This value is somewhat anomalous in that the predominantly syenitic rocks commonly yield higher values. Furthermore, heat flow is higher in areas distant from the Floridas and the radiogenic heat contribution is considered small. (orig.)

Dosimetry and radiobiology of negative pions and heavy ions

International Nuclear Information System (INIS)

Raju, M.R.

1978-01-01

The depth dose distribution of pion beams has not been found superior to protons. Pion radiation quality at the plateau region is comparable to conventional low-LET radiations, and radiobiology results also indicate RBE values close to unity. In the pion stopping region, the radiation quality increases considerably. Radiobiology data for negative pions at the Bragg peak position clearly indicate the increase in RBE and the reduction in OER. Even at the Bragg peak position, compared to fast neutrons, the average LET of negative pions is lower. Pion radiobiology data have indicated lower RBE values and higher OER values compared to fast neutrons. The radiation quality of fast neutrons is in between that of carbon and neon ions at the peak region and that of neon ions at the plateau is lower than for fast neutrons. The mean LET value for helium ions, even at the distal end of the peak, is lower than for fast neutrons. Dose localization of heavy ions has been found to decrease slowly with increasing charge of the heavy ion. The intercellular contact that protects cells after exposure to low-LET radiations is not detected after exposure to heavy ions. Single and fractionated doses of heavy ions produce dose-response curves for heavy ions having reduced shoulders but similar slopes when compared to gamma rays. Fractionated treatments of heavy ions produce an enhanced effect in the peak region compared to the plateau region and could lead to a substantial gain in therapeutic ratio. The OER for protons was similar to that for x rays. The OER values for negative pions, helium ions, and carbon ions were larger, for neon ions similar, and for argon ions smaller when compared to fast neutrons.Negative pions, helium ions, and carbon ions may be very effective clinically because the radiation quality of these beams is similar to that of the mixed scheme of neutrons and x rays

Characteristic 8 keV X rays possess radiobiological properties of higher-LET radiation.

Science.gov (United States)

Shridhar, Ravi; Estabrook, William; Yudelev, Mark; Rakowski, Joseph; Burmeister, Jay; Wilson, George D; Joiner, Michael C

2010-03-01

Electronic brachytherapy systems are being developed that can deliver X rays of varying energy depending on the material of a secondary target. A copper target produces characteristic 8 keV X rays. Our aim was to determine whether 8 keV X rays might deliver greater biological effectiveness than megavoltage photons. Cells of the U251 human glioma cell line were used to compare the biological effects of 8 keV X rays and (60)Co gamma rays in terms of relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and DNA damage. The RBE at 50% and 10% survival was 2.6 and 1.9, respectively. At 50% survival, the OER for cells treated with 8 keV X rays was 1.6 compared with 3.0 for (60)Co gamma rays. The numbers of H2AX foci per Gy after treatment with 8 keV X rays and (60)Co gamma rays were similar; however, the size of the foci generated at 8 keV was significantly larger, possibly indicating more complex DNA damage. The mean area of H2AX foci generated by 8 keV X rays was 0.785 microm(2) (95% CI: 0.756-0.814) compared with 0.491 microm(2) (95% CI: 0.462-0.520) for (60)Co gamma rays (P X rays produce two to three times the biological effectiveness of megavoltage photons, with a radiobiological profile similar to higher-LET radiations.

Functional and histological assessment of the radiobiology of normal rat lung in BNCT

International Nuclear Information System (INIS)

Kiger, J.L.; Riley, K.J.; Binns, P.J.; Harling, O.K.; Coderre, J.A.; Kiger, W.S. III; Patel, H.

2006-01-01

This study investigated the radiobiology and sensitivity of the normal rat lung to Boron Neutron Capture Therapy (BNCT) radiation. Rat thorax irradiations were carried out with x-rays or with neutrons in the presence or absence of p-boronophenylalanine (BPA). Lung damage were assessed functionally with breathing rate measurement up to 180 days after irradiation and then histologically. Breathing rates 20% (∼3 σ) above the control group (sham-irradiated rats) mean were considered as positive responses to lung radiation damage. Though most responding animals demonstrated radiation induced pneumonitis (≤110 days) as well as pulmonary fibrosis (>110 days), some animals receiving neutrons plus BPA showed only the latter. The breathing rate dose response data were fit using probit analysis. The ED 50 values measured for x-rays, neutron beam only, and neutrons plus BPA were 11.5±0.4 Gy, 9.2±0.5 Gy, and 6.7±0.4 Gy, respectively. The biological weighting factors for the neutron beam (n+γ), the thermal neutron dose component, and the 10 B dose component were determined to be 1.2±0.1, 2.2±0.4, and 2.3±0.3, respectively. The histological dose response curves were linear. Consistent with the functional assay, the weighting factors measured histologically were 1.2±0.1 for the thermal neutron beam and 1.9±0.2 for the 10 B dose component. (author)

Monte Carlo studies on photon interactions in radiobiological experiments

Science.gov (United States)

Shahmohammadi Beni, Mehrdad; Krstic, D.; Nikezic, D.

2018-01-01

X-ray and γ-ray photons have been widely used for studying radiobiological effects of ionizing radiations. Photons are indirectly ionizing radiations so they need to set in motion electrons (which are a directly ionizing radiation) to perform the ionizations. When the photon dose decreases to below a certain limit, the number of electrons set in motion will become so small that not all cells in an “exposed” cell population can get at least one electron hit. When some cells in a cell population are not hit by a directly ionizing radiation (in other words not irradiated), there will be rescue effect between the irradiated cells and non-irradiated cells, and the resultant radiobiological effect observed for the “exposed” cell population will be different. In the present paper, the mechanisms underlying photon interactions in radiobiological experiments were studied using our developed NRUphoton computer code, which was benchmarked against the MCNP5 code by comparing the photon dose delivered to the cell layer underneath the water medium. The following conclusions were reached: (1) The interaction fractions decreased in the following order: 16O > 12C > 14N > 1H. Bulges in the interaction fractions (versus water medium thickness) were observed, which reflected changes in the energies of the propagating photons due to traversals of different amount of water medium as well as changes in the energy-dependent photon interaction cross-sections. (2) Photoelectric interaction and incoherent scattering dominated for lower-energy (10 keV) and high-energy (100 keV and 1 MeV) incident photons. (3) The fractions of electron ejection from different nuclei were mainly governed by the photoelectric effect cross-sections, and the fractions from the 1s subshell were the largest. (4) The penetration fractions in general decreased with increasing medium thickness, and increased with increasing incident photon energy, the latter being explained by the corresponding reduction in

Monte Carlo studies on photon interactions in radiobiological experiments.

Directory of Open Access Journals (Sweden)

Mehrdad Shahmohammadi Beni

Full Text Available X-ray and γ-ray photons have been widely used for studying radiobiological effects of ionizing radiations. Photons are indirectly ionizing radiations so they need to set in motion electrons (which are a directly ionizing radiation to perform the ionizations. When the photon dose decreases to below a certain limit, the number of electrons set in motion will become so small that not all cells in an "exposed" cell population can get at least one electron hit. When some cells in a cell population are not hit by a directly ionizing radiation (in other words not irradiated, there will be rescue effect between the irradiated cells and non-irradiated cells, and the resultant radiobiological effect observed for the "exposed" cell population will be different. In the present paper, the mechanisms underlying photon interactions in radiobiological experiments were studied using our developed NRUphoton computer code, which was benchmarked against the MCNP5 code by comparing the photon dose delivered to the cell layer underneath the water medium. The following conclusions were reached: (1 The interaction fractions decreased in the following order: 16O > 12C > 14N > 1H. Bulges in the interaction fractions (versus water medium thickness were observed, which reflected changes in the energies of the propagating photons due to traversals of different amount of water medium as well as changes in the energy-dependent photon interaction cross-sections. (2 Photoelectric interaction and incoherent scattering dominated for lower-energy (10 keV and high-energy (100 keV and 1 MeV incident photons. (3 The fractions of electron ejection from different nuclei were mainly governed by the photoelectric effect cross-sections, and the fractions from the 1s subshell were the largest. (4 The penetration fractions in general decreased with increasing medium thickness, and increased with increasing incident photon energy, the latter being explained by the corresponding reduction in

Feasibility studies of colorless LR 115 SSNTD for alpha-particle radiobiological experiments

International Nuclear Information System (INIS)

Chan, K.F.; Tse, A.K.W.; Fong, W.F.; Yu, K.N.

2006-01-01

The feasibility of using the active layer of the colorless LR 115 SSNTD for alpha-particle radiobiological experiments was studied. The track revelation time on the bottom side (the side attached to the polyester base) was much longer than that on the top side (the side not attached to the polyester base) of the active layer so track formation on the top side was more desirable. In relation to this, culture of HeLa cells on the bottom side of the active layer was found feasible although the cultured cell number was relatively smaller. The feasibility of using this SSNTD for alpha-particle radiobiological experiments was demonstrated by culturing cells on the bottom side while performing alpha-particle irradiation and chemical etching on the top side, and by taking photographs of the cells and alpha-particle tracks together under the optical microscope

Radiobiological effects in small mammals populations dwelled at radioactive waste disposal sites

International Nuclear Information System (INIS)

Sypin, V.D.; Osipov, A.N.; Pol'skij, O.G.; Elakov, A.L.; Egorov, V.G.; Synsynys, B.I.

2004-01-01

A major issue in evaluating the ecological acceptability of a disposal system for radioactive waste is in preventing the ecological risk that may arise from exposures in the distant future. There is uncertainty surrounding any estimate of these doses or risks due to lack of knowledge about future conditions. Therefore, the adequate estimation of the ecological acceptability of a radioactive waste disposal system required a complex radioecological and radiobiological approach. Environmental surveillance at the Sergievo-Posadsky radioactive waste disposal system of the Scientific and Industrial Association Radon in additional to a standard complex radiological testing includes also the study of the radiobiological effects in different biological objects sampled from the contaminated areas. In present report the results obtained on small rodents (mice and voles) sampled from the strict mode and fence zones of this disposal system are displayed and discussed. (author)

Computer simulation in cell radiobiology

International Nuclear Information System (INIS)

Yakovlev, A.Y.; Zorin, A.V.

1988-01-01

This research monograph demonstrates the possible ways of using stochastic simulation for exploring cell kinetics, emphasizing the effects of cell radiobiology. In vitro kinetics of normal and irradiated cells is the main subject, but some approaches to the simulation of controlled cell systems are considered as well: the epithelium of the small intestine in mice taken as a case in point. Of particular interest is the evaluation of simulation modelling as a tool for gaining insight into biological processes and hence the new inferences from concrete experimental data, concerning regularities in cell population response to irradiation. The book is intended to stimulate interest among computer science specialists in developing new, more efficient means for the simulation of cell systems and to help radiobiologists in interpreting the experimental data

Comparative radiobiology of genetic loci of eukaryots as the basis of the general theory of mutations

International Nuclear Information System (INIS)

Aleksandrov, I.D.

1983-01-01

One of the fundamental problems of modern molecular cellular radiobiology is to reveal general and peculiar processes of the formation of gene mutations and chromosome aberrations in each stage of their formation in the irradiated genome of the higher eukaryots. The solution of the problems depends on the development of research within the framework of comparative radiobiology of genetic loci of the higher eukaryots that makes it possible to study quantitative regularities in the formation of gene (point) mutations and chromosome aberrations in one object and in the same experiment

Experimental radiotherapy and clinical radiobiology. Vol. 18. Proceedings

International Nuclear Information System (INIS)

Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemann, H. Peter; Zips, Daniel

2009-01-01

The proceedings on experimental radiotherapy and clinical radiobiology contain two review articles (prediction of normal tissue reactions after radiotherapy, ?H2AX foci as a marker for DNA double-strand breaks) and 34 contributions to the following topics: Hypoxia and molecular mechanisms of radiation resistance; biological imaging of the tumor micromilieu; DNA repair, genomic instability and carcerogenesis; molecular factors of radiation resistance; actual controversial discussion on possible irradiation caused metastasis risk enhancement; EGFR inhibition and irradiation; biology of experimental radiation/ normal tissue toxicity

Apoptosis, energy metabolism, and fraction of radiobiologically hypoxic cells: a study of human melanoma multicellular spheroids.

Science.gov (United States)

Rofstad, E K; Eide, K; Skøyum, R; Hystad, M E; Lyng, H

1996-09-01

The magnitude of the fraction of radiobiologically hypoxic cells in tumours is generally believed to reflect the efficiency of the vascular network. Theoretical studies have suggested that the hypoxic fraction might also be influenced by biological properties of the tumour cells. Quantitative experimental results of cell energy metabolism, hypoxia- induced apoptosis, and radiobiological hypoxia are reported here. Human melanoma multicellular spheroids (BEX-c and WIX-c) were used as tumour models to avoid confounding effects of the vascular network. Radiobiological studies showed that the fractions of hypoxic cells in 1000-microM spheroids were 32 +/- 12% (BEX-c) and 2.5 +/- 1.1% (WIX-c). The spheroid hypoxic volume fractions (28 +/- 6% (BEX-c) and 1.4 +/- 7% (WIX-c)), calculated from the rate of oxygen consumption per cell, the cell packing density, and the thickness of the viable rim, were similar to the fractions of radiobiologically hypoxic cells. Large differences between tumours in fraction of hypoxic cells are therefore not necessarily a result of differences in the efficiency of the vascular network. Studies of monolayer cell cultures, performed to identify the biological properties of the BEX-c and WIX-c cells leading to this large difference in fraction of hypoxic cells, gave the following results: (1) WIX-c showed lower cell surviving fractions after exposure to hypoxia than BEX-c, (2) WIX-c showed higher glucose uptake and lactate release rates than BEX-c both under aerobic and hypoxic conditions, and (3) hypoxia induced apoptosis in WIX-c but not in BEX-c. These observations suggested that the difference between BEX-c and WIX-c spheroids in fraction of hypoxic cells resulted partly from differences in cell energy metabolism and partly from a difference in capacity to retain viability under hypoxic stress. The induction of apoptosis by hypoxia was identified as a phenomenon which has an important influence on the magnitude of the fraction of

Physics and radiobiology of nuclear medicine

CERN Document Server

Saha, Gopal B

2013-01-01

The Fourth Edition of Dr. Gopal B. Saha’s Physics and Radiobiology of Nuclear Medicine was prompted by the need to provide up-to-date information to keep pace with the perpetual growth and improvement in the instrumentation and techniques employed in nuclear medicine since the last edition published in 2006. Like previous editions, the book is intended for radiology and nuclear medicine residents to prepare for the American Board of Nuclear Medicine, American Board of Radiology, and American Board of Science in Nuclear Medicine examinations, all of which require a strong physics background. Additionally, the book will serve as a textbook on nuclear medicine physics for nuclear medicine technologists taking the Nuclear Medicine Technology Certification Board examination.

Radiobiology: Biologic effects of ionizing radiations

International Nuclear Information System (INIS)

Held, K.D.

1987-01-01

The biologic effects after exposure to ionizing radiation, such as cell death or tissue injury, result from a chain of complex physical, chemical, metabolic, and histologic events. The time scale of these radiation actions spans many orders of magnitude. The physical absorption of ionizing radiation occurs in about 10 -18 s, while late carcinogenic and genetic effects are expressed years or even generations later. Collectively, these effects form the science of radiobiology. Many of the concepts discussed in this chapter have been developed through the study of effects generated in tissues by external radiation sources, but they apply generally and often specifically to internally distributed radiopharmaceuticals which form the central topic of this book

Radiation damage effects in solids special topic volume with invited peer reviewed papers only

CERN Document Server

Virk, Hardev Singh

2013-01-01

Public interest and concern about radiation damage effects has increased during recent times. Nuclear radiation proved to be a precursor for the study of radiation damage effects in solids. In general, all types of radiation, e.g. X-ray, gamma ray, heavy ions, fission fragments and neutrons produce damage effects in materials. Radiation damage latent tracks in solids find applications in nuclear and elementary particle physics, chemistry, radiobiology, earth sciences, nuclear engineering, and a host of other areas such as nuclear safeguards, virus counting, ion track filters, uranium exploration and archaeology. Radiation dosimetry and reactor shielding also involve concepts based on radiation damage in solids. This special volume consists of ten Chapters, including Review and Research Papers on various topics in this field.Physical scientists known to be investigating the effects of radiation on material were invited to contribute research and review papers on the areas of their specialty. The topics include...

Radiation induced DNA damage and repair in mutagenesis

International Nuclear Information System (INIS)

Strniste, G.F.; Chen, D.J.; Okinaka, R.T.

1987-01-01

The central theme in cellular radiobiological research has been the mechanisms of radiation action and the physiological response of cells to this action. Considerable effort has been directed toward the characterization of radiation-induced DNA damage and the correlation of this damage to cellular genetic change that is expressed as mutation or initiating events leading to cellular transformation and ultimately carcinogenesis. In addition, there has been a significant advancement in their understanding of the role of DNA repair in the process of mutation leading to genetic change in cells. There is extensive literature concerning studies that address radiation action in both procaryotic and eucaryotic systems. This brief report will make no attempt to summarize this voluminous data but will focus on recent results from their laboratory of experiments in which they have examined, at both the cellular and molecular levels, the process of ionizing radiation-induced mutagenesis in cultured human cells

Radiobiological research for improving tumor radiotherapy - an Indian perspective

International Nuclear Information System (INIS)

Jain, Viney

1990-01-01

Radiation-induced damage to normal tissues within the non-target volume is a major limitation of tumor radiotherapy. Physical methods to obtain superior spatial dose distributions use sophisticated technology and are expensive. Large scale applications of these technologies in a developing country like India, with a large number of cancer patients, poor instrumental facilities and inadequate infrastructure face several problems. Radiobiological research aiming at developing simple, inexpensive and effective methods to increase the differential response between tumor and normal tissues should be, therefore, strengthened. Biological end-points are determined not only by the molecular lesions produced due to the absorption of the radiation energy but also by the cellular repair processes, which become operative in response to lesions in the living system. Therefore, enhancement of repair processes in the normal tissues and inhibition of the same in tumors should considerably improve the therapeutic index of radiation treatment. A combination of agents which can suitably alter the spectrum of important molecular lesions with modifiers of cellular repair could be an effective strategy. Initial experiments using halopyrimidines to increase repairable DNA lesions produced by sparsely ionizing radiations in combination with 2-deoxy-D-glucose to modulate differentially the repair and fixation processes in the tumor and normal tissues have provided promising results. Further research work is warranted since this strategy appears to have great potential for improving tumor radiotherapy. (author). 46 refs., 4 figs., 1 tab

DOE/CEC [Department of Energy/Commission of the European Communities] workshop on critical evaluation of radiobiological data to biophysical modeling

International Nuclear Information System (INIS)

1988-01-01

The Department of Energy's Office of Health and Environmental Research and the Commission of the European Communities (CEC) Radiation Protection Program support the majority of Research in the Field of Radiobiological Modeling. This field of science develops models based on scientifically sound principles to predict biological response (at the cellular, molecular, and animal level) to exposure to low level ionizing radiation. Biophysical models are an important tool for estimating response of ionizing radiation at low doses and dose rates. Generally speaking, the biophysical models can be classified into two groups: (1) mechanistic models and (2) phenomenological models. Mechanistic models are based on some assumptions about the physical, chemical, or biological mechanisms of action in association with radiobiological data whereas the phenomenological models are based solely on available experimental data on radiobiological effects with less emphasis on mechanisms of action. There are a number of these models which are being developed. Since model builders rely on radiobiological data available in the literature either to develop mechanistic or phenomenological models, it is essential that a critical evaluation of existing radiobiological data be made and data that is generally considered good and most appropriate for biophysical modeling be identified. A Workshop jointly sponsored by the DOE and the CEC was held at Oak Ridge, Tennessee from June 23--25, 1988, to review the data available from physical and chemical, cellular and molecular and animal studies with ionizing radiation

Seasonal radiogenic isotopic variability of the African dust outflow to the tropical Atlantic Ocean and across to the Caribbean

Science.gov (United States)

Kumar, Ashwini; Abouchami, W.; Galer, S. J. G.; Singh, Satinder Pal; Fomba, K. W.; Prospero, J. M.; Andreae, M. O.

2018-04-01

In order to assess the impact of mineral dust on climate and biogeochemistry, it is paramount to identify the sources of dust emission. In this regard, radiogenic isotopes have recently been used successfully for tracing North African dust provenance and its transport across the tropical Atlantic to the Caribbean. Here we present two time series of radiogenic isotopes (Pb, Sr and Nd) in dusts collected at the Cape Verde Islands and Barbados in order to determine the origin of the dust and examine the seasonality of westerly dust outflow from Northern Africa. Aerosol samples were collected daily during two campaigns - February 2012 (winter) and June-July 2013 (summer) - at the Cape Verde Atmospheric Observatory (CVAO) on the island of São Vicente (16.9°N, 24.9°W). A one-year-long time series of aerosols from Barbados (13.16°N, 59.43°W) - a receptor region in the Caribbean - was sampled at a lower, monthly resolution. Our results resolve a seasonal isotopic signal at Cape Verde shown by daily variations, with a larger radiogenic isotope variability in winter compared to that in summer. This summer signature is also observed over Barbados, indicating similar dust provenance at both locations, despite different sampling years. This constrains the isotope fingerprint of Saharan Air Layer (SAL) dust that is well-mixed during its transport. This result provides unequivocal evidence for a permanent, albeit of variable strength, long-range transport of African dust to the Caribbean and is in full agreement with atmospheric models of North African dust emission and transport across the tropical Atlantic in the SAL. The seasonal isotopic variability is related to changes in the dust source areas - mainly the Sahara and Sahel regions - that are active all-year-round, albeit with variable contributions in summer versus the winter months. Our results provide little support for much dust contributed from the Bodélé Depression in Chad - the "dustiest" place on Earth

Amchitka radiobiological program progress report, January 1976--December 1976

International Nuclear Information System (INIS)

Nelson, V.A.; Seymour, A.H.

1977-05-01

The Amchitka Radiobiological Program is a continuing program to collect biological and environmental samples for radiometric analyses. Results of analyses for samples collected during 1976 include gamma-emitting radionuclides in air filters, freshwater, birds, lichens, marine algae, marine invertebrates, fish, aufwuchs, and freshwater moss and plants; 90 Sr in rats, birds, and soil; 239 240 Pu in sand, soil, marine algae and fish; and tritium ( 3 H) in seawater, freshwater, and biological organisms

On radiogenic nature of xenon-X in carbonaceous and LL chondrites

International Nuclear Information System (INIS)

Gerling, Eh.K.

1982-01-01

The nature of Xe-X from the mineral fraction produced during the differential dissolution of carbonaceous and LL chondrites was investigated using literature data on the age of some meteorites and their fractions and quantities of fission 136 Xe contained in them. A graph of lg fission 136 Xe against the age of meteorites was plotted; the decay constant of a hypothetical superheavy nucleus was calculated using the graph and equaled 1x10 - 7 year - 1 . The calculations served as a forcible argument for the radiogenic nature of xenon with 136 and 134 mass in carbonaceous and LL chondrites

Radiogenic age and isotopic studies: report 9. Current research 1995-F

International Nuclear Information System (INIS)

1996-01-01

'Radiogenic Age and Isotopic Studies' is an annual collection of research presentations containing U-Pb, Sm-Nd, Rb-Sr, and 40 Ar- 39 Ar data generated by the Geochronology Laboratory under the auspices of the Continental Geoscience Division, Geological Survey of Canada. Report 9 contains 5 papers from regions across Canada, followed by a compilation of 40 Ar- 39 Ar and K-Ar ages. Authors herein present data, relate results to field settings, and make brief interpretations. Readers are thus reminded that much of the research encompassed represents 'work-in-progress' and that more extensive publications may follow at a later date

A radiogenic isotope tracer study of transatlantic dust transport from Africa to the Caribbean

Science.gov (United States)

Kumar, A.; Abouchami, W.; Galer, S.J.G.; Garrison, V.H.; Williams, E.; Andreae, M.O.

2014-01-01

Many studies have suggested that long-range transport of African desert dusts across the Atlantic Ocean occurs, delivering key nutrients and contributing to fertilization of the Amazon rainforest. Here we utilize radiogenic isotope tracers – Sr, Nd and Pb – to derive the provenance, local or remote, and pathways of dust transport from Africa to the Caribbean. Atmospheric total suspended particulate (TSP) matter was collected in 2008 on quartz fibre filters, from both sides of the Atlantic Ocean at three different locations: in Mali (12.6°N, 8.0°W; 555 m a.s.l.), Tobago (11.3°N, 60.5°W; 329 m a.s.l.) and the U.S. Virgin Islands (17.7°N, 64.6°W; 27 m a.s.l.). Both the labile phase, representative of the anthropogenic signal, and the refractory detrital silicate fraction were analysed. Dust deposits and soils from around the sampling sites were measured as well to assess the potential contribution from local sources to the mineral dust collected. The contribution from anthropogenic sources of Pb was predominant in the labile, leachate phase. The overall similarity in Pb isotope signatures found in the leachates is attributed to a common African source of anthropogenic Pb, with minor inputs from other sources, such as from Central and South America. The Pb, Sr and Nd isotopic compositions in the silicate fraction were found to be systematically more radiogenic than those in the corresponding labile phases. In contrast, Nd and Sr isotopic compositions from Mali, Tobago, and the Virgin Islands are virtually identical in both leachates and residues. Comparison with existing literature data on Saharan and Sahelian sources constrains the origin of summer dust transported to the Caribbean to mainly originate from the Sahel region, with some contribution from northern Saharan sources. The source regions derived from the isotope data are consistent with 7-day back-trajectory analyses, demonstrating the usefulness of radiogenic isotopes in tracing dust provenance and

A radiogenic isotope tracer study of transatlantic dust transport from Africa to the Caribbean

Science.gov (United States)

Kumar, A.; Abouchami, W.; Galer, S. J. G.; Garrison, V. H.; Williams, E.; Andreae, M. O.

2014-01-01

Many studies have suggested that long-range transport of African desert dusts across the Atlantic Ocean occurs, delivering key nutrients and contributing to fertilization of the Amazon rainforest. Here we utilize radiogenic isotope tracers - Sr, Nd and Pb - to derive the provenance, local or remote, and pathways of dust transport from Africa to the Caribbean. Atmospheric total suspended particulate (TSP) matter was collected in 2008 on quartz fibre filters, from both sides of the Atlantic Ocean at three different locations: in Mali (12.6°N, 8.0°W; 555 m a.s.l.), Tobago (11.3°N, 60.5°W; 329 m a.s.l.) and the U.S. Virgin Islands (17.7°N, 64.6°W; 27 m a.s.l.). Both the labile phase, representative of the anthropogenic signal, and the refractory detrital silicate fraction were analysed. Dust deposits and soils from around the sampling sites were measured as well to assess the potential contribution from local sources to the mineral dust collected. The contribution from anthropogenic sources of Pb was predominant in the labile, leachate phase. The overall similarity in Pb isotope signatures found in the leachates is attributed to a common African source of anthropogenic Pb, with minor inputs from other sources, such as from Central and South America. The Pb, Sr and Nd isotopic compositions in the silicate fraction were found to be systematically more radiogenic than those in the corresponding labile phases. In contrast, Nd and Sr isotopic compositions from Mali, Tobago, and the Virgin Islands are virtually identical in both leachates and residues. Comparison with existing literature data on Saharan and Sahelian sources constrains the origin of summer dust transported to the Caribbean to mainly originate from the Sahel region, with some contribution from northern Saharan sources. The source regions derived from the isotope data are consistent with 7-day back-trajectory analyses, demonstrating the usefulness of radiogenic isotopes in tracing dust provenance and

Claudius Regaud (1870-1940): A pioneer of radiobiology and radiotherapy

International Nuclear Information System (INIS)

Foray, N.

2012-01-01

Born in 1870, Claudius Regaud was a pioneer of radiobiology and radiotherapy. As histologist, he developed a new staining technique that allowed him to describe in detail all the reproduction system of a number of animal models. As radio-biologist, he contradicted the interpretations of Tribondeau and Bergonie about relationships between cell proliferation and radiosensitivity. In 1908, he suggested that chromatin was the main target of radiation. As physician, he defined the first bases of anti-cancer radiation treatments and treated patients suffering from incurable cancer from 1911. As military doctor, he organized war hospitals by creating multidisciplinary teams for the surgery of hurts. Organizer, he was one of the founders of the League against Cancer. As radiotherapist and brachy-therapist, he contributed to make Institut Curie an international reference center for research and teaching, with nearly a thousand treated patients. As globe-trotter, he was at the origin of the creation of numerous worldwide radiotherapy and radiobiology centers. He died in December 1940 and let an impressive but still mis-known scientific heritage. A re-reading of the familial archives and the Regaud Fund of Institut Curie is the occasion to remind the contribution of Regaud. (authors)

An irradiation facility with a horizontal beam for radiobiological studies

International Nuclear Information System (INIS)

Czub, J.; Adamus, T.; Banas, D.

2006-01-01

A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw University. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as the plateau of the Bragg curve as well as in the Bragg peak. The passive beam spread out by a thin scattering foil provides a homogeneous irradiation field over an area of at least 1 x 1 cm 2 . For in vitro irradiation of biological samples the passive beam spreading combined with the x - y mechanical scanning of the irradiated sample was found to be an optimum solution. Using x - y step motor, the homogenous beam of ions with the energy loss range in the cells varied from 1 MeV/μm to 200 keV/μm is able to cover a 6 cm in diameter Petri dish that holds the biological samples. Moreover on-line fluence monitoring based on single-particle counting is performed to determine the dose absorbed by cells. Data acquisition system for dosimetry and ion monitoring based on a personal computer is described. (author)

An in vitro study of the radiobiological effects of flattening filter free radiotherapy treatments

International Nuclear Information System (INIS)

King, R B; Hyland, W B; McGarry, C K; Hounsell, A R; Cole, A J; Butterworth, K T; McMahon, S J; Redmond, K M; Trainer, C; Prise, K M

2013-01-01

Flattening filter free (FFF) linear accelerators allow for an increase in instantaneous dose-rate of the x-ray pulses by a factor of 2–6 over the conventional flattened output. As a result, radiobiological investigations are being carried out to determine the effect of these higher dose-rates on cell response. The studies reported thus far have presented conflicting results, highlighting the need for further investigation. To determine the radiobiological impact of the increased dose-rates from FFF exposures a Varian Truebeam medical linear accelerator was used to irradiate two human cancer cell lines in vitro, DU-145 prostate and H460 non-small cell lung, with both flattened and FFF 6 MV beams. The fluence profile of the FFF beam was modified using a custom-designed Nylon compensator to produce a similar dose profile to the flattened beam (6X) at the cell surface but at a higher instantaneous dose-rate. For both cell lines there appeared to be no significant change in cell survival. Curve fitting coefficients for DU145 cells irradiated with constant average dose-rates were 6X: α = 0.09 ± 0.03, β = 0.03 ± 0.01 and 6FFF: α = 0.14 ± 0.13, β = 0.03 ± 0.02 with a significance of p = 0.75. For H460 cells irradiated with the same instantaneous dose-rate but different average dose-rate the fit coefficients were 6FFF (low dose-rate): α = 0.21 ± 0.11, 0.07 ± 0.02 and 6FFF (high dose-rate): α = 0.21 ± 0.16, 0.07 ± 0.03, with p = 0.79. The results indicate that collective damage behaviour does not occur at the instantaneous dose-rates investigated here and that the use of either modality should result in the same clinical outcome, however this will require further validation in vivo. (note)

Mixed-field GCR Simulations for Radiobiological Research using Ground Based Accelerators

Science.gov (United States)

Kim, Myung-Hee Y.; Rusek, Adam; Cucinotta, Francis

Space radiation is comprised of a large number of particle types and energies, which have differential ionization power from high energy protons to high charge and energy (HZE) particles and secondary neutrons produced by galactic cosmic rays (GCR). Ground based accelerators such as the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL) are used to simulate space radiation for radiobiology research and dosimetry, electronics parts, and shielding testing using mono-energetic beams for single ion species. As a tool to support research on new risk assessment models, we have developed a stochastic model of heavy ion beams and space radiation effects, the GCR Event-based Risk Model computer code (GERMcode). For radiobiological research on mixed-field space radiation, a new GCR simulator at NSRL is proposed. The NSRL-GCR simulator, which implements the rapid switching mode and the higher energy beam extraction to 1.5 GeV/u, can integrate multiple ions into a single simulation to create GCR Z-spectrum in major energy bins. After considering the GCR environment and energy limitations of NSRL, a GCR reference field is proposed after extensive simulation studies using the GERMcode. The GCR reference field is shown to reproduce the Z and LET spectra of GCR behind shielding within 20 percents accuracy compared to simulated full GCR environments behind shielding. A major challenge for space radiobiology research is to consider chronic GCR exposure of up to 3-years in relation to simulations with cell and animal models of human risks. We discuss possible approaches to map important biological time scales in experimental models using ground-based simulation with extended exposure of up to a few weeks and fractionation approaches at a GCR simulator.

Radiobiological heterogeneity of leukemic lymphocyte precursors from acute lymphoblastic leukemia patients

International Nuclear Information System (INIS)

Uckun, F.M.; Kim, T.H.; Ramsay, N.C.; Min, W.S.; Song, C.W.

1989-01-01

The report outlines the authors' findings on the radiobiological features of leukemic lymphocyte precursors from acute lymphoblastic leukemia (ALL) patients. A marked heterogeneity existed between different cell lines, with a remarkable radioresistance and repair capacity in some ALL patients and an acute radiosensitivity in the absence of a detectable repair capacity in others. (U.K.)

Harmonization of radiobiological assays: why and how?

International Nuclear Information System (INIS)

Prasanna, Pataje G.

2014-01-01

The International Atomic Energy Agency has made available a technical manual for cytogenetic biodosimetry assays (dicentric chromosome aberration (DCA) and cytokinesis-block micronucleus (CBMN) assays) used for radiation dose assessment in radiation accidents. The International Standardization Organization, which develops standards and guidelines, also provides an avenue for laboratory accreditation, has developed guidelines and recommendations for performing cytogenetic biodosimetry assays. Harmonization of DCA and CBMN assays, has improved their accuracy. Double-blinded inter-laboratory comparison studies involving several networks have further validated DCA and CBMN assays and improved the confidence in their potential use for radiation dose assessment in mass casualties. This kind of international harmonization is lacking for pre-clinical radiobiology assays. The widely used pre-clinical assays that are relatively important to set stage for clinical trials include clonogenic assays, flow-cytometry assays, apoptotic assays, and tumor regression and growth delay assays. However, significant inter-laboratory variations occur with respect to data among laboratories. This raises concerns on the reliability and reproducibility of preclinical data that drives further development and translation. Lack of reproducibility may stem from a variety of factors such as poor scientist training, less than optimal experimental design, inadequate description of methodology, and impulse to publish only the positive data etc. Availability of technical manuals, standard operating procedures, accreditation avenues for laboratories performing such assays, inter-laboratory comparisons, and use of standardized protocols are necessary to enhance reliability and reproducibility. Thus, it is important that radiobiological assays are harmonized for laboratory protocols to ensure successful translation of pre-clinical research on radiation effect modulators to help design clinic trials with

Comparative study on fast neutrons radiobiological effect on Chinese hamster cells in culture depending on regime of irradiation

International Nuclear Information System (INIS)

Elisova, T.V.; Feoktistova, T.P.; Stavrakova, N.M.

1988-01-01

Comparative study of regularities of fast neutron radiobiological effect on Chinese hamster cells in culture under pulse and statistic irradiation regimes that was estimated by reproductive death of cells and induced frequency of resistence mutations to 6-tioguanine is carried out. It is stated that with the dose rate increase approximately by 6 orders radiobiological efficiency of fast neutrons decreases. It is suggested that one of the causes of decreasing pulse irradiation efficiency are processes on radiation-chemical level. 9 refs.; 3 figs

Radiobiological studies using gamma and x rays.

Energy Technology Data Exchange (ETDEWEB)

Potter, Charles Augustus; Longley, Susan W.; Scott, Bobby R.; Lin, Yong; Wilder, Julie; Hutt, Julie A.; Padilla, Mabel T.; Gott, Katherine M.

2013-02-01

There are approximately 500 self-shielded research irradiators used in various facilities throughout the U.S. These facilities use radioactive sources containing either 137Cs or 60Co for a variety of biological investigations. A report from the National Academy of Sciences[1] described the issues with security of particular radiation sources and the desire for their replacement. The participants in this effort prepared two peer-reviewed publications to document the results of radiobiological studies performed using photons from 320-kV x rays and 137Cs on cell cultures and mice. The effectiveness of X rays was shown to vary with cell type.

AFRRI (Armed Forces Radiobiology Research Institute) Reports, October, November and December 1987.

Science.gov (United States)

1988-03-01

pulsive motility (7), diarrhea (10), anorexia (29, present ported by the Armed Forces Radiobiology Research Institute, Defense Nuclear Agency, under...there was no significant interaction be- food than the rats with VMH lesions alone this was teen time and treatment groups (h’= 1.74. df= 12. not a

Design study of the ESS-Bilbao 50 MeV proton beam line for radiobiological studies

Energy Technology Data Exchange (ETDEWEB)

Huerta-Parajon, M., E-mail: mhuerta@essbilbao.org; Martinez-Ballarin, R., E-mail: rmartinez@essbilbao.org; Abad, E., E-mail: eabad@essbilbao.org

2015-02-01

The ESS-Bilbao proton accelerator facility has been designed fulfilling the European Spallation Source (ESS) specifications to serve as the Spanish contribution to the ESS construction. Furthermore, several applications of the ESS-Bilbao proton beam are being considered in order to contribute to the knowledge in the field of radiobiology, materials and aerospace components. Understanding of the interaction of radiation with biological systems is of vital importance as it affects important applications such as cancer treatment with ion beam therapy among others. ESS-Bilbao plans to house a facility exclusively dedicated to radiobiological experiments with protons up to 50 MeV. Beam line design, optimisation and initial calculations of flux densities and absorbed doses were undertaken using the Monte Carlo simulation package FLUKA. A proton beam with a flux density of about 10{sup 6} protons/cm{sup 2} s reaches the water sample with a flat lateral distribution of the dose. The absorbed dose at the pristine Bragg peak calculated with FLUKA is 2.4 ± 0.1 Gy in 1 min of irradiation time. This value agrees with the clinically meaningful dose rates, i.e. around 2 Gy/min, used in hadrontherapy. Optimisation and validation studies in the ESS-Bilbao line for radiobiological experiments are detailed in this article.

Radiobiologically based treatment plan evaluation for prostate seed implants

Directory of Open Access Journals (Sweden)

Sotirios Stathakis

2011-07-01

Full Text Available Purpose: Accurate prostate low dose-rate brachytherapy treatment plan evaluation is important for future care decisions. Presently, an evaluation is based on dosimetric quantifiers for the tumor and organs at risk. However, these do not account for effects of varying dose-rate, tumor repopulation and other biological effects. In this work, incorporation of the biological response is used to obtain more clinically relevant treatment plan evaluation.Material and methods: Eleven patients were evaluated. Each patient received a 145 Gy implant. Iodine-125 seeds were used and the treatment plans were created on the Prowess system. Based on CT images the post-implant plan was created. In the post-plan, the tumor, urethra, bladder and rectum were contoured. The biologically effective dose was used to determine the tumor control probability and the normal tissue complication probabilities for the urethra, bladder, rectum and surrounding tissue. Results: The average tumor control probability and complication probabilities for the urethra, bladder, rectum and surrounding tissue were 99%, 29%, 0%, 12% and 6%, respectively. These measures provide a simpler means for evaluation and since they include radiobiological factors, they provide more reliable estimation of the treatment outcome. Conclusions: The goal of this work was to create more clinically relevant prostate seed-implant evaluation by incorporating radiobiological measures. This resulted in a simpler descriptor of treatment plan quality and was consistent with patient outcomes.

Radiogenic age and isotopic studies: report 9. Current research 1995-F

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-31

`Radiogenic Age and Isotopic Studies` is an annual collection of research presentations containing U-Pb, Sm-Nd, Rb-Sr, and {sup 40}Ar-{sup 39}Ar data generated by the Geochronology Laboratory under the auspices of the Continental Geoscience Division, Geological Survey of Canada. Report 9 contains 5 papers from regions across Canada, followed by a compilation of {sup 40}Ar-{sup 39}Ar and K-Ar ages. Authors herein present data, relate results to field settings, and make brief interpretations. Readers are thus reminded that much of the research encompassed represents `work-in-progress` and that more extensive publications may follow at a later date.

LDR vs. HDR brachytherapy for localized prostate cancer: the view from radiobiological models.

Science.gov (United States)

King, Christopher R

2002-01-01

Permanent LDR brachytherapy and temporary HDR brachytherapy are competitive techniques for clinically localized prostate radiotherapy. Although a randomized trial will likely never be conducted comparing these two forms of brachytherapy, a comparative radiobiological modeling analysis proves useful in understanding some of their intrinsic differences, several of which could be exploited to improve outcomes. Radiobiological models based upon the linear quadratic equations are presented for fractionated external beam, fractionated (192)Ir HDR brachytherapy, and (125)I and (103)Pd LDR brachytherapy. These models incorporate the dose heterogeneities present in brachytherapy based upon patient-derived dose volume histograms (DVH) as well as tumor doubling times and repair kinetics. Radiobiological parameters are normalized to correspond to three accepted clinical risk factors based upon T-stage, PSA, and Gleason score to compare models with clinical series. Tumor control probabilities (TCP) for LDR and HDR brachytherapy (as monotherapy or combined with external beam) are compared with clinical bNED survival rates. Predictions are made for dose escalation with HDR brachytherapy regimens. Model predictions for dose escalation with external beam agree with clinical data and validate the models and their underlying assumptions. Both LDR and HDR brachytherapy achieve superior tumor control when compared with external beam at conventional doses (LDR brachytherapy as boost achieves superior tumor control than when used as monotherapy. Stage for stage, both LDR and current HDR regimens achieve similar tumor control rates, in agreement with current clinical data. HDR monotherapy with large-dose fraction sizes might achieve superior tumor control compared with LDR, especially if prostate cancer possesses a high sensitivity to dose fractionation (i.e., if the alpha/beta ratio is low). Radiobiological models support the current clinical evidence for equivalent outcomes in localized

SU-F-J-11: Radiobiologically Optimized Patient Localization During Prostate External Beam Localization

Energy Technology Data Exchange (ETDEWEB)

Huang, Y; Gardner, S; Liu, C; Zhao, B; Wen, N; Brown, S; Chetty, I [Henry Ford Health System, Detroit, MI (United States)

2016-06-15

Purpose: To present a novel positioning strategy which optimizes radiation delivery with radiobiological response knowledge, and to evaluate its application during prostate external beam radiotherapy. Methods: Ten patients with low or intermediate risk prostate cancer were evaluated retrospectively in this IRB-approved study. For each patient, a VMAT plan was generated on the planning CT (PCT) to deliver 78 Gy in 39 fractions with PTV = prostate + 7 mm margin, except for 5mm in the posterior direction. Five representative pretreatment CBCT images were selected for each patient, and prostate, rectum, and bladder were delineated on all CBCT images. Each CBCT was auto-registered to the corresponding PCT. Starting from this auto-matched position (AM-position), a search for optimal treatment position was performed utilizing a score function based on radiobiological and dosimetric indices (D98-DTV, NTCP-rectum, and NTCP-bladder) for the daily target volume (DTV), rectum, and bladder. DTV was defined as prostate + 4 mm margin to account for intra-fraction motion as well as contouring variability on CBCT. We termed the optimal treatment position the radiobiologically optimized couch shift position (ROCS-position). Results: The indices, averaged over the 10 patients’ treatment plans, were (mean±SD): 77.7±0.2 Gy (D98-PTV), 12.3±2.7% (NTCP-rectum), and 53.2±11.2% (NTCP-bladder). The corresponding values calculated on all 50 CBCT images at the AM-positions were 72.9±11.3 Gy (D98-DTV), 15.8±6.4% (NTCP-rectum), and 53.0±21.1% (NTCP-bladder), respectively. In comparison, calculated on CBCT at the ROCS-positions, the indices were 77.0±2.1 Gy (D98-DTV), 12.1±5.7% (NTCP-rectum), and 60.7±16.4% (NTCP-bladder). Compared to autoregistration, ROCS-optimization recovered dose coverage to target volume and lowered the risk to rectum. Moreover, NTCPrectum for one patient remained high after ROCS-optimization and therefore could potentially benefit from adaptive planning

Radiobiological research at its best. Does a low radiation dose involve risks?

International Nuclear Information System (INIS)

Baatout, S.; Jacquet, P.; Derradji, H.

2011-01-01

Radiotherapy, radiation protection, nuclear medicine, etc.: there is a growing interest in radio(bio)logy in the health care sector. The number of medical treatments with ionising radiation per year will increase even more. It is therefore increasingly important to closely monitor the possible harmful effects of low radiation doses.

Basics of radiobiology and nuclear medicine

International Nuclear Information System (INIS)

Kostadinova, I.; Hadjidekova, V.; Georgieva, R.

2002-01-01

The authors successively reveal the topics of the biological impact of radiation (radiobiology) and the diagnostic and the therapeutic application of radiopharmaceuticals (nuclear medicine). Data on the influence of radiation on subcellular, cellular, tissue and organ level are given, on early and late radiation changes, as well. Indication for the application of the different radionuclide methods in the diagnosis of the diseases in the endocrinology, nephrology, cardiology, gastroenterology, haematology of lungs, bones, tumors are pointed out and the main trends of the growing therapeutical use of nuclear medicine are presented. The aim is to teach students the nuclear medicine methods in the complex investigation of the patients, his preliminary preparation and the biological impact of radiation and its risk. Self assessment test for students are proposed and a literature for further reading

A comparison of physically and radiobiologically based optimization for IMRT

International Nuclear Information System (INIS)

Jones, Lois; Hoban, Peter

2002-01-01

Many optimization techniques for intensity modulated radiotherapy have now been developed. The majority of these techniques including all the commercial systems that are available are based on physical dose methods of assessment. Some techniques have also been based on radiobiological models. None of the radiobiological optimization techniques however have assessed the clinically realistic situation of considering both tumor and normal cells within the target volume. This study considers a ratio-based fluence optimizing technique to compare a dose-based optimization method described previously and two biologically based models. The biologically based methods use the values of equivalent uniform dose calculated for the tumor cells and integral biological effective dose for normal cells. The first biologically based method includes only tumor cells in the target volume while the second considers both tumor and normal cells in the target volume. All three methods achieve good conformation to the target volume. The biologically based optimization without the normal tissue in the target volume shows a high dose region in the center of the target volume while this is reduced when the normal tissues are also considered in the target volume. This effect occurs because the normal tissues in the target volume require the optimization to reduce the dose and therefore limit the maximum dose to that volume

Determination of damage and In vivo DNA repairing through the unicellular in gel electrophoresis technique

International Nuclear Information System (INIS)

Mendiola C, M.T.; Morales R, P.

1997-01-01

The experimental conditions were standardized for the unicellular in gel electrophoresis technique setting up (EUG) at the Cellular Radiobiology laboratory. Preliminary experiments were realized with human cells and mouse which were exposed to ionizing radiation or hydroxide peroxide (H 2 O 2 ) to induce DNA damage and to verify the technique performance. It was analysed the In vivo repairing kinetics of induced damage by gamma radiation in mouse leukocytes which were exposed to 137 Cs source and taking samples of peripheric blood of the tail of each mouse at different exposure times and processing them for EUG. In function of the cells proportion with damage in each time it was determined the existence of fast repairing mechanism at the first 15 minutes followed by a slight increase in the damage and a late repairing stage between 30 and 90 minutes. It was analysed this behavior and the potentiality of this In vivo system. (Author)

An analysis of radiation-induced damage in the spider mite. Relationship between mortality of haploid and diploid eggs in two successive generations

International Nuclear Information System (INIS)

Leenhouts, H.P.; Chadwick, K.H.

1976-01-01

Unfertilized females of the spider mite (Tetranychus urticae) produce only haploid eggs which develop into a haploid male. Fertilized females produce both haploid eggs (unfertilized), which develop into males, and diploid eggs (fertilized), which develop into females. Radiobiological experiments performed by A.M. Feldmann (Association Euratom-ITAL) made data available on the radiation-induced mortality of haploid and diploid eggs in the F 1 and F 2 generation following irradiation of either males or females with X rays or fast neutrons. The data have been analysed using the molecular theory of cell survival where it is assumed that DNA double strand breaks, induced randomly in the cell, are the critical radiation-induced lesions, which lead to cell death. Theoretical relationships are derived for the dose dependence of hatchability in haploid and diploid eggs in the first and second generations expressed as a function of the radiation damage in the parental genome. These theoretical relationships can be used to derive the inter-relationship between the different hatchabilities, and the results from the spider mite have been analysed using these considerations. It is concluded that the radiation-induced genetic damage arises from one type of initial lesion. The eventual radiobiological implications of this analysis are discussed, expecially with respect to the transmittance of radiation-induced genetic damage after low-level radiation. (author)

Relationships Between Rectal Wall Dose-Volume Constraints and Radiobiologic Indices of Toxicity for Patients With Prostate Cancer

International Nuclear Information System (INIS)

Marzi, Simona; Arcangeli, Giorgio; Saracino, Bianca; Petrongari, Maria G.; Bruzzaniti, Vicente; Iaccarino, Giuseppe; Landoni, Valeria; Soriani, Antonella; Benassi, Marcello

2007-01-01

Purpose: The purpose of this article was to investigate how exceeding specified rectal wall dose-volume constraints impacts on the risk of late rectal bleeding by using radiobiologic calculations. Methods and Materials: Dose-volume histograms (DVH) of the rectal wall of 250 patients with prostate cancer were analyzed. All patients were treated by three-dimensional conformal radiation therapy, receiving mean target doses of 80 Gy. To study the main features of the patient population, the average and the standard deviation of the distribution of DVHs were generated. The mean dose , generalized equivalent uniform dose formulation (gEUD), modified equivalent uniform dose formulation (mEUD) 0 , and normal tissue complication probability (NTCP) distributions were also produced. The DVHs set was then binned into eight classes on the basis of the exceeding or the fulfilling of three dose-volume constraints: V 40 = 60%, V 50 = 50%, and V 70 = 25%. Comparisons were made between them by , gEUD, mEUD 0 , and NTCP. Results: The radiobiologic calculations suggest that late rectal toxicity is mostly influenced by V 70 . The gEUD and mEUD 0 are risk factors of toxicity always concordant with NTCP, inside each DVH class. The mean dose, although a reliable index, may be misleading in critical situations. Conclusions: Both in three-dimensional conformal radiation therapy and particularly in intensity-modulated radiation therapy, it should be known what the relative importance of each specified dose-volume constraint is for each organ at risk. This requires a greater awareness of radiobiologic properties of tissues and radiobiologic indices may help to gradually become aware of this issue

Probability of causation for radiogenic cancer in Indian population

International Nuclear Information System (INIS)

Bhatia, D.P.; Murthy, M.S.S.

1992-01-01

The National Institute of Health (NIH), USA has generated tables for probability of causation (PC) for various radiogenic cancers for the population of United States, (NIH 1985). These are based on cancer incidence rates derived from data on the Japanese survivors of atomic bomb, followed up to 1977 and T65D dosimetry system. In 1987, Radiation Effects Research Foundation (RERF), a cooperative Japan-United States research organisation published radiation induced risk estimates (absolute and relative) using revised system of dosimetry DS86 and extended follow up of 35 years (Yukiko et al., 1988). In this paper PC has been calculated for the Indian population: i) using absolute risk estimates of RERF and NIH methodology, and ii) using the constant relative risk coefficients (CRR) of RERF. Calculations with new risk coefficients have been extended to the American population and results compared with Indian population. (author). 3 refs., 2 figs

The radiogenic hazards of working in a radiology department

International Nuclear Information System (INIS)

Russell, J.G.B.

1992-01-01

The author assesses the risks incurred by the medical personnel working in a radiology department with regard to the new estimates of risk levels for ionizing radiation delivered at low dose rates and low doses (UNSCEAR, 1988; NRPB, 1988; ICRP, 1991). It is emphasised that in deciding if the cancer has been caused by an occupational exposure, the factors to be taken into account are the radiosensitivity of the organ involved, the dose the organ has received and the time of the appearance of the cancer. Figures are provided for the radiation doses and risk of fatality of medical workers. A comparison is made with the risk of death from working in various industries. It appears that for the majority of medical radiation workers the radiogenic hazard is slight but that the hazards can be substantial for the higher dose workers. 13 refs., 2 tabs.; 1 fig

Radiogenic neoplasia in thyroid and mammary clonogens. Final progress report, 1 January 1987--31 December 1997

International Nuclear Information System (INIS)

Clifton, K.H.

1998-01-01

The induction of cancer by ionizing radiation is a matter of great practical importance to the nuclear industry, to national defense, to radiological medicine and to the general public. It is increasingly apparent that carcinogenesis is a leading dose-limiting effect of radiation exposure. The thyroid and mammary glands are among the most sensitive human tissues to radiogenic initiation of cancer, and there is a profoundly higher risk of neoplastic initiation in these glands among individuals irradiated before or during puberty than among those exposed in later life. The authors developed unique quantitative experimental models to investigate and characterize the cells of origin of thyroid and mammary cancers and the effects of radiation on them (C185). To study these progenitor cells in vivo it is necessary to have a system by which their concentrations, total numbers and responses to radiation and other factors can be measured. It is a truism that not all cells in a tissue are equally sensitive to neoplastic initiation. They reasoned that the progenitor cells are most likely members of that subpopulation that is necessary to maintenance of normal tissue cell numbers and to repair and replacement after tissue damage. They further reasoned that such cells would likely be responsive to specific mitogenic stimulation by hormones. On the basis of these considerations, they developed quantitative rat thyroid and mammary epithelial cell transplantation systems

Radiogenic neoplasia in thyroid and mammary clonogens. Final progress report, 1 January 1987--31 December 1997

Energy Technology Data Exchange (ETDEWEB)

Clifton, K.H.

1998-07-10

The induction of cancer by ionizing radiation is a matter of great practical importance to the nuclear industry, to national defense, to radiological medicine and to the general public. It is increasingly apparent that carcinogenesis is a leading dose-limiting effect of radiation exposure. The thyroid and mammary glands are among the most sensitive human tissues to radiogenic initiation of cancer, and there is a profoundly higher risk of neoplastic initiation in these glands among individuals irradiated before or during puberty than among those exposed in later life. The authors developed unique quantitative experimental models to investigate and characterize the cells of origin of thyroid and mammary cancers and the effects of radiation on them (C185). To study these progenitor cells in vivo it is necessary to have a system by which their concentrations, total numbers and responses to radiation and other factors can be measured. It is a truism that not all cells in a tissue are equally sensitive to neoplastic initiation. They reasoned that the progenitor cells are most likely members of that subpopulation that is necessary to maintenance of normal tissue cell numbers and to repair and replacement after tissue damage. They further reasoned that such cells would likely be responsive to specific mitogenic stimulation by hormones. On the basis of these considerations, they developed quantitative rat thyroid and mammary epithelial cell transplantation systems.

Regional trends in radiogenic heat generation in the Precambrian basement of the Western Canadian Basin

Science.gov (United States)

Jones, F. W.; Majorowicz, J. A.

Radiogenic heat generation values for 381 basement samples from 229 sites in the western Canadian basin exhibit a lognormal frequency distribution. The mean value = 2.06 (S.D. = 1.22) µWm-3 is larger than the radiogenic heat generation values reported for the shield in the Superior (ca. 1.2 µWm-3, Jessop and Lewis, 1978) and Churchill (ca. 0.7 µWm-3, Drury, 1985) provinces. When equal Log A contour intervals are used to map the basement heat generation, three large zones of relatively high heat generation are found. One coincides with the Peace River Arch basement structure and one with the Athabasca axis (Darnley, 1981). There is no apparent indication of increased heat flow through the Paleozoic formations associated with these two zones. The third zone, in southwestern Saskatchewan, coincides with a high heat flow zone in the Swift Current area. The lack of correlation between heat flow and heat generation in Alberta may be due to the disturbance to the heat flow in the Paleozoic formations by water motion, or may indicate that the heat is from uranium, thorium and potassium isotope enrichment near the basement surface rather than enrichment throughout the entire upper crust.

Quaternary naltrexone reverses radiogenic and morphine-induced locomotor hyperactivity

Energy Technology Data Exchange (ETDEWEB)

Mickley, G.A.; Stevens, K.E.; Galbraith, J.A.; White, G.A.; Gibbs, G.L.

1984-04-01

The present study attempted to determine the relative role of the peripheral and central nervous system in the production of morphine-induced or radiation-induced locomotor hyperactivity of the mouse. Toward this end, we used a quaternary derivative of an opiate antagonist (naltrexone methobromide), which presumably does not cross the blood-brain barrier. Quaternary naltrexone was used to challenge the stereotypic locomotor response observed in these mice after either an i.p. injection of morphine or exposure to 1500 rads /sup 60/Co. The quaternary derivative of naltrexone reversed the locomotor hyperactivity normally observed in the C57BL/6J mouse after an injection of morphine. It also significantly attenuated radiation-induced locomotion. The data reported here support the hypothesis of endorphin involvement in radiation-induced and radiogenic behaviors. However, these conclusions are contingent upon further research which more fully evaluates naltrexone methobromide's capacity to cross the blood-brain barrier.

Optimization in brachytherapy with the implementation of Radiobiology; Optimizacion en Braquiterapia con la implementacion de la Radiobiologia

Energy Technology Data Exchange (ETDEWEB)

Duran, M.P.; Bourel, V.J.; Rodriguez, I.; Torre, M. de la; Caneva, S. [Braqui S.R.L. Viamonte 1861, Buenos Aires (Argentina)

1998-12-31

In the brachytherapy planning treatments with High dose rates (HDR), the optimization algorithms used are based in dosimetric considerations and/or geometric ones, ignoring the radiobiological response of the tissue treated. In this work we wish to show the implementation of radiobiological concepts in the optimization. Assuming that the subtiles differences that result in the dose distribution among the different optimization models which are not visible in an isodose plane, it is studied how is classically make it , the quality implant through natural histograms about dose volumes and the resulting parameters. Also is studied the necrosis probability which may be caused by the choice of some optimization model, allowing with this the choice of the best implant. (Author)

On occurrence of a neurogenic sarcoma in irradiation area after combined operative-radiogenic therapy of an adenosarcoma in kidney during childhood

International Nuclear Information System (INIS)

Eberhardt, H.J.; Friedrich, S.; Herrmann, T.; Roy, U.

1990-01-01

Malignant neoplasias in childhood generally are an increased risk for the patient to fall ill with a second tumor. Second tumors in former irradiation field are seldom, but are acknowledged radiogenically if histology is different to that of the first tumor and a sufficiently long period is between the two tumors. A patient is presented who had been operated and irradiated because of an adenosarcoma of the kidney at the age of seven and who has fallen ill with a neurogenic sarcoma in the irradiation area more than 30 years later. The same patient had to suffer from radiogenic retardation during differentiation of the lumbar apparatus of attitude and locomotion and on the other hand be became father of a healthy daughter at the age of 32. (author)

Low LET protons focused to submicrometer shows enhanced radiobiological effectiveness

Science.gov (United States)

Schmid, T. E.; Greubel, C.; Hable, V.; Zlobinskaya, O.; Michalski, D.; Girst, S.; Siebenwirth, C.; Schmid, E.; Molls, M.; Multhoff, G.; Dollinger, G.

2012-10-01

This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm-1) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBEMN = 1.48 ± 0.07) and dicentrics (RBED = 1.92 ± 0.15), in human-hamster hybrid (AL) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm2 matrix compared to quasi homogeneous in a 1 × 1 µm2 matrix applied protons (RBEMN = 1.28 ± 0.07; RBED = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a 12C ion with 55 MeV total energy (4.48 MeV u-1). The enhancements are about half of that obtained for 12C ions (RBEMN = 2.20 ± 0.06 and RBED = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles.

Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells.

Science.gov (United States)

Laschinsky, Lydia; Karsch, Leonhard; Leßmann, Elisabeth; Oppelt, Melanie; Pawelke, Jörg; Richter, Christian; Schürer, Michael; Beyreuther, Elke

2016-08-01

Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10(10) Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone.

Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells

International Nuclear Information System (INIS)

Laschinsky, Lydia; Karsch, Leonhard; Schuerer, Michael; Lessmann, Elisabeth; Beyreuther, Elke; Oppelt, Melanie; Pawelke, Joerg; Richter, Christian

2016-01-01

Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10"1"0 Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone. (orig.)

Hypofractionated radiation induces a decrease in cell proliferation but no histological damage to organotypic multicellular spheroids of human glioblastomas

International Nuclear Information System (INIS)

Kaaijk, P.; Academic Medical Center, Amsterdam; Troost, D.; Leenstra, S.; Bosch, D.A.; Sminia, P.; Hulshof, M.C.C.M..; Kracht, A.H.W. van der

1997-01-01

The aim of this study was to examine the effect of radiation on glioblastoma, using an organotypic multicellular spheroid (OMS) model. Most glioblastoma cell lines are, in contrast to glioblastomas in vivo, relatively radiosensitive. This limits the value of using cell lines for studying the radiation effect of glioblastomas. The advantage of OMS is maintenance of the characteristics of the original tumour, which is lost in conventional cell cultures. OMS prepared from four glioblastomas were treated with hypofractionated radiation with a radiobiologically equivalent dose to standard radiation treatment for glioblastomas patients. After treatment, the histology as well as the cell proliferation of the OMS was examined. After radiation, a significant decrease in cell proliferation was found, although no histological damage to the OMS was observed. The modest effects of radiation on the OMS are in agreement with the limited therapeutic value of radiotherapy for glioblastoma patients. Therefore, OMS seems to be a good alternative for cell lines to study the radiobiological effect on glioblastomas. (author)

Hypofractionated radiation induces a decrease in cell proliferation but no histological damage to organotypic multicellular spheroids of human glioblastomas

Energy Technology Data Exchange (ETDEWEB)

Kaaijk, P [Academic Medical Center, Amsterdam (Netherlands). Dept. of (Neuro) Pathology; [Academic Medical Center, Amsterdam (Netherlands). Dept. of Neurosurgery; Troost, D [Academic Medical Center, Amsterdam (Netherlands). Dept. of (Neuro) Pathology; Leenstra, S; Bosch, D A [Academic Medical Center, Amsterdam (Netherlands). Dept. of Neurosurgery; Sminia, P; Hulshof, M C.C.M.; Kracht, A.H.W. van der [Academic Medical Center, Amsterdam (Netherlands). Dept. of (Experimental) Radiotherapy

1997-04-01

The aim of this study was to examine the effect of radiation on glioblastoma, using an organotypic multicellular spheroid (OMS) model. Most glioblastoma cell lines are, in contrast to glioblastomas in vivo, relatively radiosensitive. This limits the value of using cell lines for studying the radiation effect of glioblastomas. The advantage of OMS is maintenance of the characteristics of the original tumour, which is lost in conventional cell cultures. OMS prepared from four glioblastomas were treated with hypofractionated radiation with a radiobiologically equivalent dose to standard radiation treatment for glioblastomas patients. After treatment, the histology as well as the cell proliferation of the OMS was examined. After radiation, a significant decrease in cell proliferation was found, although no histological damage to the OMS was observed. The modest effects of radiation on the OMS are in agreement with the limited therapeutic value of radiotherapy for glioblastoma patients. Therefore, OMS seems to be a good alternative for cell lines to study the radiobiological effect on glioblastomas. (author).

Transfer of Minibeam Radiation Therapy into a cost-effective equipment for radiobiological studies: a proof of concept.

Science.gov (United States)

Prezado, Y; Dos Santos, M; Gonzalez, W; Jouvion, G; Guardiola, C; Heinrich, S; Labiod, D; Juchaux, M; Jourdain, L; Sebrie, C; Pouzoulet, F

2017-12-11

Minibeam radiation therapy (MBRT) is an innovative synchrotron radiotherapy technique able to shift the normal tissue complication probability curves to significantly higher doses. However, its exploration was hindered due to the limited and expensive beamtime at synchrotrons. The aim of this work was to develop a cost-effective equipment to perform systematic radiobiological studies in view of MBRT. Tumor control for various tumor entities will be addressable as well as studies to unravel the distinct biological mechanisms involved in normal and tumor tissues responses when applying MBRT. With that aim, a series of modifications of a small animal irradiator were performed to make it suitable for MBRT experiments. In addition, the brains of two groups of rats were irradiated. Half of the animals received a standard irradiation, the other half, MBRT. The animals were followed-up for 6.5 months. Substantial brain damage was observed in the group receiving standard RT, in contrast to the MBRT group, where no significant lesions were observed. This work proves the feasibility of the transfer of MBRT outside synchrotron sources towards a small animal irradiator.

Radiobiological investigations of soft X-rays near carbon, nitrogen, oxygen K-shell edges on Aspergillus oryzae spores

International Nuclear Information System (INIS)

Chen, L.; Jiang, S. P.; Wan, L. B.; Ma, X. D.; Li, M. F.

2008-01-01

Soft X-rays at carbon, nitrogen, oxygen K-shell edges have special radiobiological effects. Using Aspergillus oryzae spores as sample, the radiation effects of soft X-rays near the K-shell edges of C, N and O elements from synchrotron radiation were investigated. Also the dose depositions of different X-ray energies in spore were discussed. At the same time, the spores were irradiated by gamma rays from 60 Co and relative biological effects were compared with those produced by soft X-rays. The results showed that soft X-rays near K-shell edges of O element had higher ability of radiation damage than that of X-rays near K-shell edges of C and N elements as compared with one another. But they all had higher killing abilities per unit dose than that of gamma rays from 60 Co. The relative biological effects (RBEs), the comparison of dose to gamma rays at 10% survival level, of the three soft X-rays were 1.65, 1.73 and 1.91, respectively. (authors)

Stable and Radiogenic Sr Isotopes in Barite - Clues on the Links Between Weathering, Climate and the C Cycle

Science.gov (United States)

Paytan, A.; Eisenhauer, A.; Wallmann, K. J. G.; Griffith, E. M.; Ridgwell, A.

2017-12-01

The radiogenic Sr-isotopic signature (87Sr/86Sr) of seawater fluctuates primarily in response to changes in the inputs of Sr from weathering and hydrothermal activity, which have distinct 87Sr/86Sr values. Changes in the isotopic ratio of the weathered terrain also contribute to observed changes in 87Sr/86Sr. The stable Sr-isotope ratios in seawater (mass dependent isotopic fractionation; δ88/86Sr) fluctuate primarily in response to the rate of calcium carbonate (CaCO3) accumulation at the seafloor. Together the radiogenic and stable Sr can constrain the coupling between weathering and sedimentation and shed light on the relation between weathering, CaCO3 deposition, the global carbon (C) cycle and climate. Reconstruction of the coupled stable and radiogenic Sr seawater curves over the past 35 Ma of Earth history indicates that the location and rate of CaCO3 burial in the ocean fluctuated considerably over the past 35 Ma. Between 35 to 18 Ma a reduction in neritic CaCO3 burial and increased burial in pelagic settings is observed. The trend was reversed between 20 and 3 Ma and finally over the last 3 million years a rapid change from neritic to pelagic burial is seen. The lack of continues increase of pelagic CaCO3 burial rates suggests that silicate weathering rates have not increased monotonically over the past 35 Ma implying strong feedbacks operating in the climate system - lower atmospheric pCO2 and cooling trends (which control chemical weathering as seen from carbonate deposition in the ocean) countered the effects of uplift (which controls physical weathering) - modulating weathering rates and preventing a runaway ice-house. In addition the data suggests considerable fluctuations in seawater Sr concentrations over time. These data demonstrate how using multiple isotope proxies can help constrain interpretations of the geological record.

Basic radiation protection education and training for medical professionals; Georgian experience and future perspective

International Nuclear Information System (INIS)

Todua, F.; Nadareishvili, D.; Ormotsadze, G.; Sanikidze, T.

2016-01-01

The level of knowledge provided by the Tbilisi State Medical University (TSMU) standard curriculum modules in 'Medical physics' and 'Radiation risk estimates' was assessed as was the learning outcome of modern standards elective course in 'Radiation protection'. Two groups of medical students were examined: Group 1: 5 y students, participants in elective course 'Radiobiology and radiogenic health risk' and Group 2: 1-2 y students, participants in winter and summer schools. Students were tested before and after training courses with the same tests questionnaire. The results of the tests showed the necessity for improvement of the educational curriculum. The changes needed are the inclusion of a basic radiobiological course in the curricula of the faculty of medicine and expansion of the medical physics course through a more detailed presentation of medical imaging methods. (authors)

A note on modeling of tumor regression for estimation of radiobiological parameters

International Nuclear Information System (INIS)

Zhong, Hualiang; Chetty, Indrin

2014-01-01

Purpose: Accurate calculation of radiobiological parameters is crucial to predicting radiation treatment response. Modeling differences may have a significant impact on derived parameters. In this study, the authors have integrated two existing models with kinetic differential equations to formulate a new tumor regression model for estimation of radiobiological parameters for individual patients. Methods: A system of differential equations that characterizes the birth-and-death process of tumor cells in radiation treatment was analytically solved. The solution of this system was used to construct an iterative model (Z-model). The model consists of three parameters: tumor doubling time T d , half-life of dead cells T r , and cell survival fraction SF D under dose D. The Jacobian determinant of this model was proposed as a constraint to optimize the three parameters for six head and neck cancer patients. The derived parameters were compared with those generated from the two existing models: Chvetsov's model (C-model) and Lim's model (L-model). The C-model and L-model were optimized with the parameter T d fixed. Results: With the Jacobian-constrained Z-model, the mean of the optimized cell survival fractions is 0.43 ± 0.08, and the half-life of dead cells averaged over the six patients is 17.5 ± 3.2 days. The parameters T r and SF D optimized with the Z-model differ by 1.2% and 20.3% from those optimized with the T d -fixed C-model, and by 32.1% and 112.3% from those optimized with the T d -fixed L-model, respectively. Conclusions: The Z-model was analytically constructed from the differential equations of cell populations that describe changes in the number of different tumor cells during the course of radiation treatment. The Jacobian constraints were proposed to optimize the three radiobiological parameters. The generated model and its optimization method may help develop high-quality treatment regimens for individual patients

A comparative study of the radiobiologic risks from three different TMJ (temporary modular joint) radiographic techniques using a pan-tomographic system

International Nuclear Information System (INIS)

Chilvarquer, Israel.

1992-01-01

The aim of this study was the obtention of the absorbed doses to critical organs for evaluating and comparing the radiobiologic risks from three different TMJ radiographic techniques, using a pantomographic system, utilizing a combination of rare-earth screens to fast films. The compared techniques were the conventional panoramic technique, the Manufacture's recommended technique for TMJ and the Chilvarquer's technique. The absorber doses were measured by exposing a phantom, fitted with fluoride TLD in fourteen sites distributed at the Thyroid, Pituitary, Salivary glands sites distributed at the Thyroid, Pituitary, Salivary glands and at the bone marrow. The radiobiologic risks were calculated using the UNSCEAR 34 (1977), and the fatal cancer incidence for age and sex was calculated using the ICRP 29 (1977). Based on the obtained data, it was concluded that the Chilvarquer's technique induced the lowest absorbed doses and the estimated radiobiologic risks were lower than a cancer per a million of examinations. (author). 108 refs., 19 figs., 14 tabs

SU-E-T-194: From Dicom-RT to Radiobiological Dose Metrics in 5 Minutes

Energy Technology Data Exchange (ETDEWEB)

Whelan, B; Holloway, L

2014-06-01

Purpose: To develop a flexible and standalone framework for batch calculation of radiobiological dose metrics from Dicom-RT. Methods: Software has been developed which allows (1) The calculation of DVH data from DICOM dose and structure files (DVHgenerator), (2) Calculation of a wide range of radiobiological metrics from this data (CompPlanGui). Both these tools are run via graphical user interface (GUI), making them fast and simple. Part 1 is a new tool which has not previously been published, whilst part 2 is a GUI overlay for the previously published software ‘Comp-Plan’ (Holloway et. al., Medical Dosimetry, 2012), previously reliant on command line interface. The time taken for an experienced user to evaluate a test case of 6 plans with and without CompPlanGUI was quantified. Results: The DVH-generator has been found to be faster, more robust and require far less physical memory then using alternative software solutions for the same purpose. The Comp Plan GUI significantly reduces the amount of time required to set up a base directory, eliminates code crashes arising from typographical errors, and renders the code far more accessible to non-expert users. It took an experienced user of the code around 3 minutes to set up a base directory of 6 plans compared around 8 minutes without, indicating that using CompPlanGUI reduced setup time by over 50%. Conclusion: A standalone GUI based framework has developed which allows for the batch calculation of radiobiological dose metrics directly from Dicom-RT files. As with the original code, this work will be made freely available on request, as well as via matlab file exchange.

Repair of radiation damage caused by cyclotron-produced neutrons

International Nuclear Information System (INIS)

Martins, B.I.

1979-01-01

Hall et al. present experimental data on repair of sublethal damage in cultured mammalian cells exposed to 35 MeV neutrons and 60 Co γ rays. Hall and Kraljevic present experimental data on repair of potentially lethal damage in cultured mammalian cells exposed to 35 MeV neutrons and 210 kVp x rays. These results of Hall et al. are very difficult to explain from basic concepts in radiobiology. Contrary to Rossi, these data do not support his thesis that repair of radiation damage is dose-dependent and linear energy transfer independent. Nor do these results meet the expectations of multitarget-single hit theory which would require dose-independent repair equal to n. The observation of the same extrapolation number for neutrons and for x rays is also surprising. From the point of view of radiotherapy, the doses of interest are about 140 rad for neutrons and about 300 rad for x rays. There are no data for repair of potentially lethal damage below 800 rad for x rays and 400 rad for neutrons. The difference in survival between single and split dose is negligible up to a total of about 600 rad of x rays or of neutrons. These data of Hall et al. therefore have little significance to radiotherapists and are an enigma to radiobiologists

Radiogenic leukemia risk analysis for the Techa River Cohort members

International Nuclear Information System (INIS)

Krestinina, L.Y.; Epifanova, S.B.; Akleyev, A.V.; Preston, D.; Davis, F.; Ron, E.

2008-01-01

Full text: Members of the Techa River Cohort have been exposed to a long-term external and internal irradiation due to releases of radioactive waste from the Mayak Production Association into the Techa River. Since internal exposure resulted primarily from incorporation of 90 Sr in the bone structure, the bone marrow was the principal target. The maximum dose to the red bone marrow accumulated over 50 years in cohort members reached 2 Gy, and the mean dose was 0.3 Gy. The epidemiological analysis of radiogenic risk of leukemia development was conducted based on the retrospective cohort study approach and regression analysis using the Epicure statistical packet. The extended Techa River Cohort (ETRC) includes about 30 thousand people of the two genders, various ages and different ethnicity (mostly Russians, Tartars and Bashkirs). The catchment area for leukemia mortality and incidence follow-up includes the whole Chelyabinsk and Kurgan Oblasts. The previous analysis of leukemia mortality risk for a 50-year follow-up period pointed out statistically significant dose dependence. The presentation will for the first time describe the results of leukemia incidence risk analyses for the period from 1953 through 2004. Over this 52-year follow-up period 92 leukemia cases (42 in men and 50 in women) were registered among ETRC members resident in the catchment area. Among those 92 cases there were 22 cases attributed to chronic lymphoid leukemia (12 in men and 10 in women). The preliminary analysis of leukemia incidence risk showed a statistically significant linear dependence on dose for total leukemias (p = 0.006), as well as for leukemias with CLL excluded (p < 0.001). The point value of the total leukemia incidence ERR was 2.0/Gy (95% CI: 0.4-15.4) and for leukemia with CLL excluded the ERR was 4.5/Gy (95% CI: 1.1-14.7). More than 57% of leukemia cases (excluding CLL) registered in ETRC members could be related to the radiogenic factor. Analyses of chronic lymphoid

Prognosticating and pharmacological prophylaxis of radiogenic malignant tumours

International Nuclear Information System (INIS)

Muksinova, K.N.; Kirillova, E.N.; Rabinovich, E.I.; Mushkacheva, G.S.; Revina, E.S.; Lemberg, V.K.

1996-01-01

Cancerogenic effect risks due to ionizing radiation, that impacted on large population groups because of Chernobyl and other accidents, cause the actuality of early diagnosis problems and of radiogenic tumour prevention. Since canceroembryonic antigen and α-fetoprotein had been found, the tumour markers began to be frequently used by oncologists. However, attempt to use onco-markers, as test for earlier pre-clinic determination, have been unsuccessful. The secondary messengers of hormonal signal, cyclic nucleotides, that take the leading place in system of organism self-regulation, had attracted our attention. As known, the increase of cell division number and suppression of morphological and biochemical developments of differentiation are the fundamental characteristics of tumour growth and are proceeding together with participating of cyclic nucleotide system. The including of both nucleotides in neoplastic transformation and at the same time their constant presence in extracellular fluid (blood serum, urine) makes the perspective use of these compounds as indicators of tumour growth before the appearance of clinic signs of diseases. This coincides with the modern viewpoints on the developments of optimum programs for pre-clinic diagnosing of tumours, that needs to base on the change in homeostasis preceded the malignant tumour development. (author)

Morphine tolerance offers protection from radiogenic performance deficits

International Nuclear Information System (INIS)

Mickley, G.A.; Stevens, K.E.; Burrows, J.M.; White, G.A.; Gibbs, G.L.

1983-01-01

When rats are exposed to a sufficiently large dose of ionizing radiation they exhibit lethargy, hypokinesia, and deficits in performance. These and other behavioral changes parallel those often observed in this species after a large dose of morphine. Since the release of endogenous opiates has been implicated in some stress reactions, we sought to determine if they might play a part in radiogenic behavioral deficits. Rats were trained to criterion on a signaled avoidance task. Some subjects were then implanted with a pellet containing 75 mg of morphine. Other animals received placebo implants. Over a number of days, morphine tolerance was evaluated by measurement of body temperature changes. Prior to 2500 rad 60 Co exposure or sham irradiation, morphine (or placebo) pellets were removed. Twenty-four hours later rats were retested to assess their performance on the avoidance task. Morphine-tolerant subjects performed significantly better than the irradiated placebo-implanted group and no differently than morphine-tolerant/sham-irradiated animals. Morphine tolerance seems to provide a degree of behavioral radiation resistance. These data are consistent with the hypothesis that endogenous opiate hyperexcretion may play some part in the behavioral deficits often observed after irradiation

Installation of a flow cytometry facility and some applications in radiobiology

International Nuclear Information System (INIS)

Walsh, M.; Kellington, J.P.

1988-01-01

Flow cytometry has enormous potential in many areas of experimental pathology. Details of the installation and commissioning of a flow cytometer at the Harwell Laboratory are described. Following an explanation of the principles of flow cytometry, several applications to specific problems in radiobiology are discussed. Also included are results of some preliminary studies with the Harwell flow cytometer on samples such as blood, bone marrow, macrophages and cell cultures, and a discussion of future applications. (author)

[From microdosimetry to nanodosimetry--the link between radiobiology and radiation physics].

Science.gov (United States)

Fu, Yuchuan; Li, Ping

2014-06-01

The link between micro- and macro-parameters for radiation interactions that take place in living biological systems is described in this paper. Meanwhile recent progress and development in microdosimetry and nanodosimetry are introduced, including the methods to measure and calculate these micro- or nano-parameters. The relationship between radiobiology and physical quantities in microdosimetry and nanodosimetry was presented. Both the current problems on their applications in radiation protection and radiotherapy and the future development direction are proposed.

Biophysical and biomathematical adventures in radiobiology

International Nuclear Information System (INIS)

Scott, B.R.

1991-01-01

Highlights of my biophysical and biomathematical adventures in radiobiology is presented. Early adventures involved developing ''state-vector models'' for specific harmful effects (cell killing, life shortening) of exposure to radiation. More recent adventures led to developing ''hazard-function models'' for predicting biological effects (e.g., cell killing, mutations, tumor induction) of combined exposure to different toxicants. Hazard-function models were also developed for predicting harm to man from exposure to large radiation doses. Major conclusions derived from the modeling adventures are as follows: (1) synergistic effects of different genotoxic agents should not occur at low doses; (2) for exposure of the lung or bone marrow to large doses of photon radiation, low rates of exposure should be better tolerated than high rates; and (3) for some types of radiation (e.g., alpha particles and fission neutrons), moderate doses delivered at a low rate may be more harmful than the same dose given at a high rate. 53 refs., 7 figs

Radiobiology 2000: advances in fundamental and clinical radiobiology. Programme and abstracts: 1st international congress of the South African Radiobiology Society (SARS) in conjunction with the South African Association of Physicists in Medicine and Biology (SAAPMB) and the University of Stellenbosch, 10-13 December 2000, Music Conservatoire, University of Stellenbosch

International Nuclear Information System (INIS)

2000-12-01

Programme and abstracts of the 1st international congress of the South African Radiobiology Society, held in conjunction with the South African Association of Physicists in Medicine and Biology and the University of Stellenbosch, from 10-13 December 2000. This publication contain the abstracts of the forty-four papers and posters that were presented

A detailed radiobiological and dosimetric analysis of biochemical outcomes in a case-control study of permanent prostate brachytherapy patients

International Nuclear Information System (INIS)

Butler, Wayne M.; Stewart, Renee R.; Merrick, Gregory S.

2009-01-01

The purpose of this study is to determine dosimetric and radiobiological predictors of biochemical control after recalculation of prostate implant dosimetry using updated AAPM Task Group 43 (TG-43) parameters and the radiobiological parameters recommended by TG-137. All biochemical failures among patients implanted with 125 I or 103 Pd sources between 1994 and March 2006 were matched 2:1 with nonfailure controls. The individual matching was by risk group, radionuclide, prescribed dose, and time of implant (one match before and one after the failed patient) resulting in a median follow-up of 10.9 years. Complete dose volume histogram (DVH) data were recalculated for all 55 cases and 110 controls after updating the original source strength by the retrospectively determined ratios of TG-43. Differential DVH data were acquired in 179 increments of prostate volume versus percentage prescribed dose. At each incremental dose level i, the biologically equivalent dose BED i , equivalent uniform dose EUD i , and tumor control probability TCP i were calculated from the implant dose plus any external beam delivered to the patient. Total BED, EUD, and TCP were then derived from the incremental values for comparison with single point dosimetric quality parameters and DVH-based averages. There was no significant difference between failures and controls in terms of total BED (143 vs 142 Gy), EUD (95 vs 94 Gy), or TCP (0.87 vs 0.89). Conditional logistic regression analysis factored out the matching variables and stratified the cohort into each case and its controls, but no radiobiological parameter was predictive of biochemical failure. However, there was a significant difference between radiobiological parameters of 125 I and 103 Pd due to less complete coverage of the target volume by the former isotope. The implant BED and TCP were highly correlated with the D 90 and natural prescription doses and a series of mean DVH-based doses such as the harmonic mean and expressions of the

Skin damage probabilities using fixation materials in high-energy photon beams

International Nuclear Information System (INIS)

Carl, J.; Vestergaard, A.

2000-01-01

Patient fixation, such as thermoplastic masks, carbon-fibre support plates and polystyrene bead vacuum cradles, is used to reproduce patient positioning in radiotherapy. Consequently low-density materials may be introduced in high-energy photon beams. The aim of the this study was to measure the increase in skin dose when low-density materials are present and calculate the radiobiological consequences in terms of probabilities of early and late skin damage. An experimental thin-windowed plane-parallel ion chamber was used. Skin doses were measured using various overlaying low-density fixation materials. A fixed geometry of a 10 x 10 cm field, a SSD = 100 cm and photon energies of 4, 6 and 10 MV on Varian Clinac 2100C accelerators were used for all measurements. Radiobiological consequences of introducing these materials into the high-energy photon beams were evaluated in terms of early and late damage of the skin based on the measured surface doses and the LQ-model. The experimental ion chamber save results consistent with other studies. A relationship between skin dose and material thickness in mg/cm 2 was established and used to calculate skin doses in scenarios assuming radiotherapy treatment with opposed fields. Conventional radiotherapy may apply mid-point doses up to 60-66 Gy in daily 2-Gy fractions opposed fields. Using thermoplastic fixation and high-energy photons as low as 4 MV do increase the dose to the skin considerably. However, using thermoplastic materials with thickness less than 100 mg/cm 2 skin doses are comparable with those produced by variation in source to skin distance, field size or blocking trays within clinical treatment set-ups. The use of polystyrene cradles and carbon-fibre materials with thickness less than 100 mg/cm 2 should be avoided at 4 MV at doses above 54-60 Gy. (author)

IMRT optimization: Variability of solutions and its radiobiological impact

International Nuclear Information System (INIS)

Mattia, Maurizio; Del Giudice, Paolo; Caccia, Barbara

2004-01-01

We aim at (1) defining and measuring a 'complexity' index for the optimization process of an intensity modulated radiation therapy treatment plan (IMRT TP), (2) devising an efficient approximate optimization strategy, and (3) evaluating the impact of the complexity of the optimization process on the radiobiological quality of the treatment. In this work, for a prostate therapy case, the IMRT TP optimization problem has been formulated in terms of dose-volume constraints. The cost function has been minimized in order to achieve the optimal solution, by means of an iterative procedure, which is repeated for many initial modulation profiles, and for each of them the final optimal solution is recorded. To explore the complexity of the space of such solutions we have chosen to minimize the cost function with an algorithm that is unable to avoid local minima. The size of the (sub)optimal solutions distribution is taken as an indicator of the complexity of the optimization problem. The impact of the estimated complexity on the probability of success of the therapy is evaluated using radiobiological indicators (Poissonian TCP model [S. Webb and A. E. Nahum, Phys. Med. Biol. 38(6), 653-666 (1993)] and NTCP relative seriality model [Kallman et al., Int. J. Radiat. Biol. 62(2), 249-262 (1992)]). We find in the examined prostate case a nontrivial distribution of local minima, which has symmetry properties allowing a good estimate of near-optimal solutions with a moderate computational load. We finally demonstrate that reducing the a priori uncertainty in the optimal solution results in a significant improvement of the probability of success of the TP, based on TCP and NTCP estimates

Method for validating radiobiological samples using a linear accelerator.

Science.gov (United States)

Brengues, Muriel; Liu, David; Korn, Ronald; Zenhausern, Frederic

2014-04-29

There is an immediate need for rapid triage of the population in case of a large scale exposure to ionizing radiation. Knowing the dose absorbed by the body will allow clinicians to administer medical treatment for the best chance of recovery for the victim. In addition, today's radiotherapy treatment could benefit from additional information regarding the patient's sensitivity to radiation before starting the treatment. As of today, there is no system in place to respond to this demand. This paper will describe specific procedures to mimic the effects of human exposure to ionizing radiation creating the tools for optimization of administered radiation dosimetry for radiotherapy and/or to estimate the doses of radiation received accidentally during a radiation event that could pose a danger to the public. In order to obtain irradiated biological samples to study ionizing radiation absorbed by the body, we performed ex-vivo irradiation of human blood samples using the linear accelerator (LINAC). The LINAC was implemented and calibrated for irradiating human whole blood samples. To test the calibration, a 2 Gy test run was successfully performed on a tube filled with water with an accuracy of 3% in dose distribution. To validate our technique the blood samples were ex-vivo irradiated and the results were analyzed using a gene expression assay to follow the effect of the ionizing irradiation by characterizing dose responsive biomarkers from radiobiological assays. The response of 5 genes was monitored resulting in expression increase with the dose of radiation received. The blood samples treated with the LINAC can provide effective irradiated blood samples suitable for molecular profiling to validate radiobiological measurements via the gene-expression based biodosimetry tools.

Radiological and Environmental Research Division, Center for Human Radiobiology. Annual report, July 1980-June 1981

International Nuclear Information System (INIS)

1982-03-01

Separate abstracts were prepared for the 22 papers of this annual report of the Center for Human Radiobiology. Abstracts were not written for 2 appendices which contain data on the exposure and radium-induced malignancies of 2259 persons whose radium content has been determined at least once

Low LET protons focused to submicrometer shows enhanced radiobiological effectiveness

International Nuclear Information System (INIS)

Schmid, T E; Zlobinskaya, O; Michalski, D; Molls, M; Multhoff, G; Greubel, C; Hable, V; Girst, S; Siebenwirth, C; Dollinger, G; Schmid, E

2012-01-01

This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm −1 ) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBE MN = 1.48 ± 0.07) and dicentrics (RBE D = 1.92 ± 0.15), in human–hamster hybrid (A L ) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm 2 matrix compared to quasi homogeneous in a 1 × 1 µm 2 matrix applied protons (RBE MN = 1.28 ± 0.07; RBE D = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a 12 C ion with 55 MeV total energy (4.48 MeV u −1 ). The enhancements are about half of that obtained for 12 C ions (RBE MN = 2.20 ± 0.06 and RBE D = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles. (paper)

Radiobiology of hypofractionated stereotactic radiotherapy: what are the optimal fractionation schedules?

International Nuclear Information System (INIS)

Shibamoto, Yuta; Miyakawa, Akifumi; Otsuka, Shinya; Iwata, Hiromitsu

2016-01-01

In hypofractionated stereotactic radiotherapy (SRT), high doses per fraction are usually used and the dose delivery pattern is different from that of conventional radiation. The daily dose is usually given intermittently over a longer time compared with conventional radiotherapy. During prolonged radiation delivery, sublethal damage repair takes place, leading to the decreased effect of radiation. In in vivo tumors, however, this decrease in effect may be counterbalanced by rapid reoxygenation. Another issue related to hypofractionated SRT is the mathematical model for dose evaluation and conversion. The linear–quadratic (LQ) model and biologically effective dose (BED) have been suggested to be incorrect when used for hypofractionation. The LQ model overestimates the effect of high fractional doses of radiation. BED is particularly incorrect when used for tumor responses in vivo, since it does not take reoxygenation into account. Correction of the errors, estimated at 5–20%, associated with the use of BED is necessary when it is used for SRT. High fractional doses have been reported to exhibit effects against tumor vasculature and enhance host immunity, leading to increased antitumor effects. This may be an interesting topic that should be further investigated. Radioresistance of hypoxic tumor cells is more problematic in hypofractionated SRT, so trials of hypoxia-targeted agents are encouraged in the future. In this review, the radiobiological characteristics of hypofractionated SRT are summarized, and based on the considerations, we would like to recommend 60 Gy in eight fractions delivered three times a week for lung tumors larger than 2 cm in diameter

In vitro and in vivo ion beam targeted micro-irradiation for radiobiology

International Nuclear Information System (INIS)

Vianna, Francois

2014-01-01

The main goal of radiobiology is to understand the effects of ionizing radiations on the living. These past decades, ion microbeams have shown to be important tools to study for example the effects of low dose exposure, or the bystander effect. Since 2003, the CENBG has been equipped with a system to perform targeted micro-irradiation of living samples. Recently, microbeams applications on this subject have diversified and the study of DNA repair mechanisms at the cellular and multicellular scales, in vitro and in vivo, has become possible thanks to important evolutions of fluorescence imaging techniques and cellular biology. To take into account these new approaches, the CENBG micro-irradiation beamline has been entirely redesigned and rebuilt to implement new features and to improve the existing ones. My PhD objectives were i) commissioning the facility, ii) characterizing the system on track etch detectors, and on living samples, iii) implementing protocols to perform targeted irradiations of living samples with a con-trolled delivered dose, at the cellular and multicellular scales, and to visualize the early consequences online, iv) modelling these irradiations to explain the biological results using the calculated physical data. The work of these past years has allowed us i) to measure the performances of our system: a beam spot size of about 2 μm and a targeting accuracy of ± 2 μm, and to develop ion detection systems for an absolute delivered dose control, ii) to create highly localized radiation-induced DNA damages and to see online the recruitment of DNA repair proteins, iii) to apply these protocols to generate radiation-induced DNA damages in vivo inside a multicellular organism at the embryonic stage: Caenorhabditis elegans. These results have opened up many perspectives on the study of the interaction between ionizing radiations and the living, at the cellular and multicellular scales, in vitro and in vivo. (author) [fr

Activities of the radiobiological institute, the institute for experimental gerontology, and the primate center. Annual report, 1976

International Nuclear Information System (INIS)

1976-01-01

Activities, presented by way of concise articles, cover the following subjects: radiation physics, radiobiology, experimental tumor therapy, tumor induction and tumor biology, immunology, transplantation and immunogenetics, hematology, gerontology, ethology, microbiology and quotobiology, techniques, and animals

A community call for a dedicated radiobiological research facility to support particle beam cancer therapy

DEFF Research Database (Denmark)

Holzscheiter, Michael H.; Bassler, Niels; Dosanjh, Manjit

2012-01-01

Recently more than one hundred researchers followed an invitation to a brainstorming meeting on the topic of a future dedicated radio-biological and radio-physical research center. 100 more joint the meeting via webcast. After a day of presentations and discussions it was clear, that an urgent need...

Use of the NASA Space Radiation Laboratory at Brookhaven National Laboratory to Conduct Charged Particle Radiobiology Studies Relevant to Ion Therapy.

Science.gov (United States)

Held, Kathryn D; Blakely, Eleanor A; Story, Michael D; Lowenstein, Derek I

2016-06-01

Although clinical studies with carbon ions have been conducted successfully in Japan and Europe, the limited radiobiological information about charged particles that are heavier than protons remains a significant impediment to exploiting the full potential of particle therapy. There is growing interest in the U.S. to build a cancer treatment facility that utilizes charged particles heavier than protons. Therefore, it is essential that additional radiobiological knowledge be obtained using state-of-the-art technologies and biological models and end points relevant to clinical outcome. Currently, most such ion radiotherapy-related research is being conducted outside the U.S. This article addresses the substantial contributions to that research that are possible at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), which is the only facility in the U.S. at this time where heavy-ion radiobiology research with the ion species and energies of interest for therapy can be done. Here, we briefly discuss the relevant facilities at NSRL and how selected charged particle biology research gaps could be addressed using those facilities.

Ages and Growth of the Continental Crust from Radiogenic Isotopes

Science.gov (United States)

Patchett, P. J.; Samson, S. D.

2003-12-01

The development and application of radiogenic isotopes to dating of geologic events, and to questions of growth, evolution, and recycling processes in the continental crust are mature areas of scientific inquiry. By this we understand that many of the approaches used to date rocks and constrain the evolution of the continents are well established, even routine, and that the scope of data available on age and evolution of continents is very large. This is not to say that new approaches have not been developed in recent years, or that new approaches and/or insights cannot be developed in the future. However, the science of continental crustal evolution is definitely a domain where many of the problems are well defined, the power of the techniques used to solve them are well known, and the limitations of field and laboratory databases, as well as the preserved geologic record, are understood.From the very early days of crustal evolution studies, it was innovations and improvements in laboratory techniques that drove the pace of discovery (e.g., Holmes, 1911; Nier, 1939). This remained true through all the increments in capability reviewed in this chapter, up to the present day. Thus, continental crustal evolution is an area of Earth science where a species of very laboratory-oriented investigator, the "radiogenic isotope geologist" or "geochronologist," has made major advances, even breakthroughs, in understanding. This is true in spite of the fact that many of the individuals of the species may have lacked field expertise, or even more than a primitive level of geologic background. Because design and building of instruments like radiation detectors or mass spectrometers requires a knowledge of physics, many of the early practitioners of rock dating were physicists, like Alfred Nier (cited above). Since the 1970s, essentially all mass spectrometers have been constructed by specialized commercial firms, and the level of physics expertise among isotope geologists has

Radiobiological effects of heavy ions and protons. [on cells of mammals, bacteria and viruses

Science.gov (United States)

Ryzhov, N. I.; Vorozhtsova, S. V.; Krasavin, Y. A.; Mashinskaya, T. Y.; Savchenko, N. Y.; Fedorov, B. S.; Khlaponina, V. F.; Shelegedin, V. N.; Gut, L.; Sabo, L.

1974-01-01

Radiobiological effects of heavy ions and protons are studied on cells of mammals, bacteria, viruses and DNA of bacteria. Results show that the dose effect dependence bears an exponential character; the reduction of RBE as LET of particle increases reflects the different character of microdistribution of absorbed energy in biological objects with different levels of biological organization.

In vitro irradiation system for radiobiological experiments

International Nuclear Information System (INIS)

Tesei, Anna; Zoli, Wainer; D’Errico, Vincenzo; Romeo, Antonino; Parisi, Elisabetta; Polico, Rolando; Sarnelli, Anna; Arienti, Chiara; Menghi, Enrico; Medri, Laura; Gabucci, Elisa; Pignatta, Sara; Falconi, Mirella; Silvestrini, Rosella

2013-01-01

Although two-dimensional (2-D) monolayer cell cultures provide important information on basic tumor biology and radiobiology, they are not representative of the complexity of three-dimensional (3-D) solid tumors. In particular, new models reproducing clinical conditions as closely as possible are needed for radiobiological studies to provide information that can be translated from bench to bedside. We developed a novel system for the irradiation, under sterile conditions, of 3-D tumor spheroids, the in vitro model considered as a bridge between the complex architectural organization of in vivo tumors and the very simple one of in vitro monolayer cell cultures. The system exploits the same equipment as that used for patient treatments, without the need for dedicated and highly expensive instruments. To mimic the passage of radiation beams through human tissues before they reach the target tumor mass, 96-multiwell plates containing the multicellular tumor spheroids (MCTS) are inserted into a custom-built phantom made of plexiglass, the material most similar to water, the main component of human tissue. The system was used to irradiate CAEP- and A549-derived MCTS, pre-treated or not with 20 μM cisplatin, with a dose of 20 Gy delivered in one session. We also tested the same treatment schemes on monolayer CAEP and A549 cells. Our preliminary results indicated a significant increment in radiotoxicity 20 days after the end of irradiation in the CAEP spheroids pre-treated with cisplatin compared to those treated with cisplatin or irradiation alone. Conversely, the effect of the radio- chemotherapy combination in A549-derived MCTS was similar to that induced by cisplatin or irradiation alone. Finally, the 20 Gy dose did not affect cell survival in monolayer CAEP and A549 cells, whereas cisplatin or cisplatin plus radiation caused 100% cell death, regardless of the type of cell line used. We set up a system for the irradiation, under sterile conditions, of tumor cells

Radiobiological modelling of dose-gradient effects in low dose rate, high dose rate and pulsed brachytherapy

International Nuclear Information System (INIS)

Armpilia, C; Dale, R G; Sandilos, P; Vlachos, L

2006-01-01

This paper presents a generalization of a previously published methodology which quantified the radiobiological consequences of dose-gradient effects in brachytherapy applications. The methodology uses the linear-quadratic (LQ) formulation to identify an equivalent biologically effective dose (BED eq ) which, if applied uniformly to a specified tissue volume, would produce the same net cell survival as that achieved by a given non-uniform brachytherapy application. Multiplying factors (MFs), which enable the equivalent BED for an enclosed volume to be estimated from the BED calculated at the dose reference surface, have been calculated and tabulated for both spherical and cylindrical geometries. The main types of brachytherapy (high dose rate (HDR), low dose rate (LDR) and pulsed (PB)) have been examined for a range of radiobiological parameters/dimensions. Equivalent BEDs are consistently higher than the BEDs calculated at the reference surface by an amount which depends on the treatment prescription (magnitude of the prescribed dose) at the reference point. MFs are closely related to the numerical BED values, irrespective of how the original BED was attained (e.g., via HDR, LDR or PB). Thus, an average MF can be used for a given prescribed BED as it will be largely independent of the assumed radiobiological parameters (radiosensitivity and α/β) and standardized look-up tables may be applicable to all types of brachytherapy treatment. This analysis opens the way to more systematic approaches for correlating physical and biological effects in several types of brachytherapy and for the improved quantitative assessment and ranking of clinical treatments which involve a brachytherapy component

Paul Scherrer Institut annual report 1995. Annex II: PSI life sciences and institute for medical radiobiology newsletter 1995

Energy Technology Data Exchange (ETDEWEB)

Blaeuenstein, P; Gschwend, B [eds.

1996-09-01

The newsletter presents the 1995 progress report of PSI F2-Department and of the Institute for Medical Radiobiology in the fields of radiation medicine, radiopharmacy and radiation hygiene. figs., tabs., refs.

Paul Scherrer Institut annual report 1995. Annex II: PSI life sciences and institute for medical radiobiology newsletter 1995

International Nuclear Information System (INIS)

Blaeuenstein, P.; Gschwend, B.

1996-01-01

The newsletter presents the 1995 progress report of PSI F2-Department and of the Institute for Medical Radiobiology in the fields of radiation medicine, radiopharmacy and radiation hygiene. figs., tabs., refs

Method for validating radiobiological samples using a linear accelerator

International Nuclear Information System (INIS)

Brengues, Muriel; Liu, David; Korn, Ronald; Zenhausern, Frederic

2014-01-01

There is an immediate need for rapid triage of the population in case of a large scale exposure to ionizing radiation. Knowing the dose absorbed by the body will allow clinicians to administer medical treatment for the best chance of recovery for the victim. In addition, today's radiotherapy treatment could benefit from additional information regarding the patient's sensitivity to radiation before starting the treatment. As of today, there is no system in place to respond to this demand. This paper will describe specific procedures to mimic the effects of human exposure to ionizing radiation creating the tools for optimization of administered radiation dosimetry for radiotherapy and/or to estimate the doses of radiation received accidentally during a radiation event that could pose a danger to the public. In order to obtain irradiated biological samples to study ionizing radiation absorbed by the body, we performed ex-vivo irradiation of human blood samples using the linear accelerator (LINAC). The LINAC was implemented and calibrated for irradiating human whole blood samples. To test the calibration, a 2 Gy test run was successfully performed on a tube filled with water with an accuracy of 3% in dose distribution. To validate our technique the blood samples were ex-vivo irradiated and the results were analyzed using a gene expression assay to follow the effect of the ionizing irradiation by characterizing dose responsive biomarkers from radiobiological assays. The response of 5 genes was monitored resulting in expression increase with the dose of radiation received. The blood samples treated with the LINAC can provide effective irradiated blood samples suitable for molecular profiling to validate radiobiological measurements via the gene-expression based biodosimetry tools. (orig.)

Radiation-induced normal tissue damage: implications for radiotherapy

International Nuclear Information System (INIS)

Prasanna, Pataje G.

2014-01-01

Radiotherapy is an important treatment modality for many malignancies, either alone or as a part of combined modality treatment. However, despite technological advances in physical treatment delivery, patients suffer adverse effects from radiation therapy due to normal tissue damage. These side effects may be acute, occurring during or within weeks after therapy, or intermediate to late, occurring months to years after therapy. Minimizing normal tissue damage from radiotherapy will allow enhancement of tumor killing and improve tumor control and patients quality of life. Understanding mechanisms through which radiation toxicity develops in normal tissue will facilitate the development of next generation radiation effect modulators. Translation of these agents to the clinic will also require an understanding of the impact of these protectors and mitigators on tumor radiation response. In addition, normal tissues vary in radiobiologically important ways, including organ sensitivity to radiation, cellular turnover rate, and differences in mechanisms of injury manifestation and damage response. Therefore, successful development of radiation modulators may require multiple approaches to address organ/site-specific needs. These may include treatments that modify cellular damage and death processes, inflammation, alteration of normal flora, wound healing, tissue regeneration and others, specifically to counter cancer site-specific adverse effects. Further, an understanding of mechanisms of normal tissue damage will allow development of predictive biomarkers; however harmonization of such assays is critical. This is a necessary step towards patient-specific treatment customization. Examples of important adverse effects of radiotherapy either alone or in conjunction with chemotherapy, and important limitations in the current approaches of using radioprotectors for improving therapeutic outcome will be highlighted. (author)

Radiogenic male breast cancer with in vitro sensitivity to ionizing radiation and bleomycin

International Nuclear Information System (INIS)

Greene, M.H.; Goedert, J.J.; Bech-Hansen, N.T.; McGuire, D.; Paterson, M.C.; Fraumeni, J.F. Jr.

1983-01-01

A cytogenetically normal man with gynecomastia and a family history of diverse cancers developed adenocarcinoma of the breast 30 years following thymic irradiation. In vitro experiments measuring colony-forming ability of cultured skin fibroblasts from family members implied that the patient had a small but significant increase in sensitivity to ionizing radiation, and a moderate increase in sensitivity to bleomycin, a radiomimetic drug. Enhanced radiosensitivity of fibroblasts from the patient's mother, and bleomycin sensitivity of fibroblasts from the sister suggested, but did not prove, that genetic susceptibility affected the risk of radiogenic cancer in this individual. In vitro studies of cancer-prone kindreds are a useful research strategy in delineating mechanisms of carcinogenesis

Radon as a remedy - radiobiological and medical aspects, risk

International Nuclear Information System (INIS)

Schwarz, E.R.; Nuernberger, E.; Martignoni, K.

1995-01-01

For years there have been controversial discussions about the benefit and risk of radon-balneo-therapy. This is particularly true where the inhalation of radon and its daughter products in curative galleries is concerned. Animal experiments and studies on uranium miners have clearly shown that the exposure with radon and its daughter products is connected with an additional risk for lung cancer. Findings on balneo-therapeutic mechanisms are, at best, incomplete and the topic of controversial discussions in radiobiology. This applies specifically to 'hormesis' or 'adaptive response', as indicated in this context. Given the numerous reports of therapeutic results, there appear to be curative effects from radon-balneotherapy for special indications. (orig.) [de

Common genomic signaling among initial DNA damage and radiation-induced apoptosis in peripheral blood lymphocytes from locally advanced breast cancer patients

DEFF Research Database (Denmark)

Henríquez-Hernández, Luis Alberto; Pinar, Beatriz; Carmona-Vigo, Ruth

2013-01-01

PURPOSE: To investigate the genomic signaling that defines sensitive lymphocytes to radiation and if such molecular profiles are consistent with clinical toxicity; trying to disclose the radiobiology mechanisms behind these cellular processes. PATIENTS AND METHODS: Twelve consecutive patients...... suffering from locally advanced breast cancer and treated with high-dose hyperfractionated radiotherapy were recruited. Initial DNA damage was measured by pulsed-field gel electrophoresis and radiation-induced apoptosis was measured by flow cytometry. Gene expression was assessed by DNA microarray. RESULTS...

FISH as A method for detection of radiation Induced genetic damage

International Nuclear Information System (INIS)

Lakatosova, M.; Holeckova, B.

2006-01-01

Fluorescence in situ hybridization (FISH) has been considered as a suitable method for rapid and easy detection of chromosome aberrations. In contrast to the standard conventional staining procedure, this technique enables the detection and specification of stable chromosomal re-arrangements, which are compatible with cellular division and thus, they could be transmitted from common ancestral to next cell generations. FISH chromosome - specific painting probes have been effectively applied for the detection of chromosomal damage after exposure to radiation. During last years, several specific fluorescent labeled probes were performed that allowed precise detection of centromeres, sub-telomeres or other regions (sequences) in genome. Our paper deals with describing of different types of FISH probes and their possibilities for application in radiobiology. (authors)

Preliminary study on proteomic technique in radiobiological characteristics in nasopharyngeal carcinoma cell line

International Nuclear Information System (INIS)

Wang Hui; Yi Xuping; Hu Bingqiang; Zeng Liang; Liu Yisong; Liang Songping

2007-01-01

Objective: To examine the variation of protein expression in nasopharyngeal carcinoma cell lines with different biological characteristics and to identify the radiobiological associated proteins. Methods: Biological characteristics of 5-8F and 6-10B were compared by flow cytometry assay after irradiation. The total proteins of 5-8F and 6-10B were separated by immobilized pH gradient(IPG) IEF-SDS two-dimensional gel eleetrophoresis technique. The differentially expressed proteins were cut from the gel and digested into peptides for MALDI-TOF MS and the Q-TOF mass spectrometric analysis. Identification of protein was made through searching in protein sequence database. Protein expressions were examined by western blot and immunohistochemistry method. Results: Nine most differentially expressed proteins between 5-8F cell and 6-10B cell were identified, p73 and CK19 expression examined by western blot were conformal with that by proteomic method, p73 expression in 5-8F cell was higher than in 6-10B cell. CK19 expression in 6- 10B cell was higher than in 5-8F cell. Conclusion: Differentially expression of proteins exist in nasopharyngeal carcinoma cell lines with different biological characteristics. These proteins may be associated with cell radiobiological characteristic with the p73 as a potential biomarker. (authors)

Design of a radiation facility for very small specimens used in radiobiology studies

Science.gov (United States)

Rodriguez, Manuel; Jeraj, Robert

2008-06-01

A design of a radiation facility for very small specimens used in radiobiology is presented. This micro-irradiator has been primarily designed to irradiate partial bodies in zebrafish embryos 3-4 mm in length. A miniature x-ray, 50 kV photon beam, is used as a radiation source. The source is inserted in a cylindrical brass collimator that has a pinhole of 1.0 mm in diameter along the central axis to produce a pencil photon beam. The collimator with the source is attached underneath a computer-controlled movable table which holds the specimens. Using a 45° tilted mirror, a digital camera, connected to the computer, takes pictures of the specimen and the pinhole collimator. From the image provided by the camera, the relative distance from the specimen to the pinhole axis is calculated and coordinates are sent to the movable table to properly position the samples in the beam path. Due to its monitoring system, characteristic of the radiation beam, accuracy and precision of specimen positioning, and automatic image-based specimen recognition, this radiation facility is a suitable tool to irradiate partial bodies in zebrafish embryos, cell cultures or any other small specimen used in radiobiology research.

Dictionary of radiation protection, radiobiology and nuclear medicine. English-German-French-Russian

International Nuclear Information System (INIS)

Sube, R.

1985-01-01

This multilingual dictionary covers the subject fields of radiation protection, radiobiology, and nuclear medicine with about 12,000 terms in each language. All terms are supplemented by one or more abbreviations of 22 special branches to assure the use of the very relevant terms. Special branches listed are for instance decontamination, dosimetry, atomic legislation, radiation detectors, radiography (medical), radiotherapy, safeguards, shielding, tansportation and storage. The terminology used in the International Nuclear Information System (INIS) of the IAEA has been completely taken into account

Intermolecular-directed reactivity in solid media. Radiogenic formation of phosphorus-centered radicals in chiral diphosphine disulfides studied by ESR

Energy Technology Data Exchange (ETDEWEB)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M. (Eindhoven Univ. of Technology (Netherlands)); Kanters, J.A.; Schouten, A. (State Univ. of Utrecht (Netherlands))

1990-07-04

Single-crystal, powder, and frozen-matrix ESR experiments have been performed to study the radiogenic electron-capture properties of several diastereoisomeric and asymmetric diphosphine disulfides (R{sub 1}R{sub 2}P(S)P(S)R{sub 3}R{sub 4}). The principal values of the hyperfine couplings of several phosphorus-centered radical configurations are determined and related to the spin density distribution. Attention is focused on the strong differences in radiogenic properties, observed between the meso and racemic forms of phenyl- and tolyl-substituted diphosphine disulfides. The most striking result is that X irradiation of the crystalline meso compounds MePhP(S)P(S)MePh, Me(p-Tol)P(S)P(S)Me(p-Tol), and Ph(PhCH{sub 2})P(S)P(S)Ph(CH{sub 2}Ph) does not lead to the formation of a three-electron bond P-P {sigma}* radical but invariably results in configurations in which the unpaired electron is primarily localized on one half of the molecule. X irradiation of the corresponding racemic forms, on the other hand, gives rise to P-P {sigma}* configurations.

Expression of Wnt-1, TGF-β and related cell–cell adhesion components following radiotherapy in salivary glands of patients with manifested radiogenic xerostomia

International Nuclear Information System (INIS)

Hakim, Samer George; Ribbat, Julika; Berndt, Alexander; Richter, Petra; Kosmehl, Hartwig; Benedek, Geza A.; Jacobsen, Hans Christian; Trenkle, Thomas; Sieg, Peter; Rades, Dirk

2011-01-01

Background: Radiation-induced xerostomia still represents a common symptom following radiotherapy of head and neck malignancies, which significantly impairs the patient’s quality of life. In this cross-sectional study, human salivary glands were investigated to assess the role of Wnt/β-catenin and TGF-β pathways in the pathogenic process of radiogenic impairment of salivary function. Methods: Irradiated human salivary glands were investigated in patients with manifested xerostomia. Alteration of Wnt-1 and cell–cell adhesion was evaluated immunohistologically as well as changes in the expression of TGF-β were assessed in salivary gland tissue. Results: We assessed two alteration patterns in which Wnt-1 expression represents one change along with up-regulation of β-catenin and E-cadherin in irradiated but viable acinar cells. Increased expression of tenascin-C was observed in sites of epithelial–mesenchymal interaction and loss of cell–cell adhesion was assessed in translocated epithelial cells in the stroma. Conclusion: Increased transdifferentiation and remodeling of acinar structures was associated with decrease of viable acinar structures. The role of Wnt and TGF signaling may provide a potential therapeutic approach to prevent radiation-induced damage to salivary glands during radiotherapy for head and neck cancer.

Radiobiological parameters of a human tumor parent line and four tumor clones of a human epidermoid carcinoma

International Nuclear Information System (INIS)

Weichselbaum, R.R.; Beckett, M.; Dahlberg, W.

1987-01-01

The authors examined the radiobiological parameters of a parent tumor line and four tumor clones of a human squamous cell carcinoma of the skin. The parent line and clones have a tumor morphology, aneuploid karyotype, and the ability to passage continuously in vitro. With the exception of clone F2A, all cell lines form tumors in nude mice. The parent line, SCC-12 has a D/sub o/ of 154 and an n 7.5 In four tumor clones, D/sub o/ ranges from 131 (clone V) to 266 (clone B2); n ranges from 22.8 in clone V to 2.1 in clone B2. PLDR following 1100 rad ranges from 1.7 in clone B2 to 13.1 in clone V. However, PLDR following equitoxic doses of radiation is similar in the parent and all sub-clones. Radiobiological heterogeneity may complicate predictive assays for clinical radiotherapy

Screening of microbial radiation-inducible promoter and study of its expression; Development of basic technique of radiogenic therapy

Energy Technology Data Exchange (ETDEWEB)

Lim, Sangyong; Kim Dongho; Yang, Jaeseung

2007-02-15

In the search for new therapeutic modalities for cancer, gene therapy has attracted enormous interest over the last few years. Recently, the use of bacteria as a tumor specific protein transfer system has attracted interest. Attenuated Salmonella has been shown to provide selective colonization in tumors. This strategy to apply gene therapy for cancer has been defined as 'Radiogenic Therapy'. In this research, firstly, we screened a radiation inducible promoter of Salmonella responding to clinically relevant low dose of 10 Gy using microarray analysis. Of all genes showing a expression ratio of at least 2-fold changes relative to wild type, 168 genes were induced. To confirm the findings of the microarray by an alternative method, we investigated the transcriptional changes of radio-inducible genes using real time PCR analysis. To verify the ability of screened genes (fadB, narK, cyoA, STM1011, STM2617, and STM2632) to produce a downstream protein by irradiation, the reporter plasmids were constructed. Finally, we found that the promoter of fadB, cyoA, and STM2617 can be activated by irradiation within cancer cells. These results suggest that these genes may be the most probable candidate used in radiogenic therapy.

Screening of microbial radiation-inducible promoter and study of its expression; Development of basic technique of radiogenic therapy

International Nuclear Information System (INIS)

Lim, Sangyong; Kim Dongho; Yang, Jaeseung

2007-02-01

In the search for new therapeutic modalities for cancer, gene therapy has attracted enormous interest over the last few years. Recently, the use of bacteria as a tumor specific protein transfer system has attracted interest. Attenuated Salmonella has been shown to provide selective colonization in tumors. This strategy to apply gene therapy for cancer has been defined as 'Radiogenic Therapy'. In this research, firstly, we screened a radiation inducible promoter of Salmonella responding to clinically relevant low dose of 10 Gy using microarray analysis. Of all genes showing a expression ratio of at least 2-fold changes relative to wild type, 168 genes were induced. To confirm the findings of the microarray by an alternative method, we investigated the transcriptional changes of radio-inducible genes using real time PCR analysis. To verify the ability of screened genes (fadB, narK, cyoA, STM1011, STM2617, and STM2632) to produce a downstream protein by irradiation, the reporter plasmids were constructed. Finally, we found that the promoter of fadB, cyoA, and STM2617 can be activated by irradiation within cancer cells. These results suggest that these genes may be the most probable candidate used in radiogenic therapy

Radiobiological work using a negative pion beam at the Rutherford Laboratory 1971-76

International Nuclear Information System (INIS)

Ellis, R.E.; Lindop, P.J.; Coggle, J.E.; Fraser, G.

1976-08-01

The subject is discussed in two sections: physics experiments (including, inter alia, dose measurement, LET distribution, radiation products of spallation); radiobiological studies (including separate reports as follows: review of experimental programme; some in vivo effects of negative pions in mice; survival and recovery of Hela cells in vitro; negative pion dose-response curves for frozen Hela cells; response of vicia faba to irradiation with negative pions; pion experiments with chromosome aberrations). (U.K.)

Paul Scherrer Institut annual report 1996. Annex II: PSI life sciences and Institute for Medical Radiobiology Newsletter 1996

International Nuclear Information System (INIS)

Kuehne, G.; Gschwend, B.

1997-01-01

This annex to the PSI Annual Report 1996 reports on the progress achieved by the PSI Department II during 1996 in the fields of radiation medicine, radiopharmacy, radiation hygiene, positron emission tomography and medical radiobiology. figs., tab., refs

Tumor radiobiology studies with heavy charged-particle beams

International Nuclear Information System (INIS)

Curtis, S.B.; Tenforde, T.S.; Tenforde, S.D.; Parr, S.S.; Flynn, M.J.

1981-01-01

The response of tumor-cell systems to irradiation with carbon, neon, and argon beams at various positions in the plateau and extended peak regions of the Bragg ionization (dose versus depth) curve is being evaluated from experiments conducted both in vivo and in vitro. The radiobiological end points being studied include: tumor volume response, cellular survival after tumor irradiation in situ, cell-kinetic parameters measured by flow cytofluorometry and time-lapse cinematography, and survival of oxic and hypoxic cells irradiated in suspension. One focus of the research effort during the past year has been on the combined effect of radiosensitizing drugs and charged-particle irradiation. In this article, the results are presented of studies on combined drug and radiation treatment of a rat rhabdomyosarcoma tumor and a human melanoma tumor growing in athymic (thymus-less) nude mice

Model for radiation damage in cells by direct effect and by indirect effect: a radiation chemistry approach

International Nuclear Information System (INIS)

Michaels, H.B.; Hunt, J.W.

1978-01-01

A model is presented to describe the contributions of direct and indirect effects to the radiation damage of cells. The model is derived using principles of radiation chemistry and of pulse radiolysis in particular. From data available in the literature, parameters for cellular composition and values of rate constants for indirect action have been used in preliminary applications of the model. The results obtained in calculations of the protective effect of .OH and .H scavengers are consistent with experimental data. Possible modifications and improvements to the model are suggested, along with proposed future applications of the model in radiobiological studies

Radiogenic neoplasia in thyroid and mammary clonogens

International Nuclear Information System (INIS)

Clifton, K.H.

1991-01-01

We have developed rat thyroid and mammary clonogen transplantation systems for the study of radiogenic cancer induction at the target cell level in vivo. The epithelial cell populations of both glands contain small subpopulations of cells which are capable of giving rise to monoclonal glandular structures when transplanted and stimulated with appropriate hormones. During the end of the last grant year and the first half of the current grant year, we have completed analyses and summarized for publication: investigations on the relationship between grafted thyroid cell number and the rapidity and degree of reestablishment of the thyroid-hypothalamicpituitary axis in thyroidectomized rats maintained on a normal diet or an iodine deficient diet; studies of the persistence of, and the differentiation potential and functional characteristics of, the TSH- (thyrotropin-) responsive sub-population of clonogens during goitrogenesis, the plateau-phase of goiter growth, and goiter involution; studies of changes in the size of the clonogen sub-population during goitrogenesis, goiter involution and the response to goitrogen rechallenge; and the results of the large carcinogenesis experiment on the nature of the grafted thyroid cell number-dependent suppression of promotion/progression to neoplasia in grafts of radiation-initiated thyroid cells. We are testing new techniques for the culture, cytofluorescent analysis and characterization mammary epithelial cells and of clonogens in a parallel project, and plan to apply similar technology to the thyroid epithelial cells and clonogen population. Data from these studies will be used in the design of future carcinogenesis experiments on neoplastic initiation by high and low LET radiations and on cells interactions during the neoplastic process

Linear versus non-linear: a perspective from health physics and radiobiology

International Nuclear Information System (INIS)

Gentner, N.E.; Osborne, R.V.

1998-01-01

There is a vigorous debate about whether or not there may be a 'threshold' for radiation-induced adverse health effects. A linear-no threshold (LNT) model allows radiation protection practitioners to manage putative risk consistently, because different types of exposure, exposures at different times, and exposures to different organs may be summed. If we are to argue to regulators and the public that low doses are less dangerous than we presently assume, it is incumbent on us to prove this. The question is, therefore, whether any consonant body of evidence exists that the risk of low doses has been over-estimated. From the perspectives of both health physics and radiobiology, we conclude that the evidence for linearity at high doses (and arguably of fairly small total doses if delivered at high dose rate) is strong. For low doses (or in fact, even for fairly high doses) delivered at low dose rate, the evidence is much less compelling. Since statistical limitations at low doses are almost always going to prevent a definitive answer, one way or the other, from human data, we need a way out of this epistemological dilemma of 'LNT or not LNT, that is the question'. To our minds, the path forward is to exploit (1) radiobiological studies which address directly the question of what the dose and dose rate effectiveness factor is in actual human bodies exposed to low-level radiation, in concert with (2) epidemiological studies of human populations exposed to fairly high doses (to obtain statistical power) but where exposure was protracted over some years. (author)

Radiogenic changes in the behavior and physiology of the spontaneously hypertensive rat: evidence for a dissociation between acute hypotension and incapacitation

International Nuclear Information System (INIS)

Mickley, G.A.; Teitelbaum, H.; Parker, G.A.; Vieras, F.; Dennison, B.A.; Bonney, C.H.

1982-01-01

Immediately following exposure to a sufficiently large dose of ionizing radiation, rats and several other species experience a transient period of acute hypotension and an accompanying deficit in performance. Although significant correlations have been reported between the drop in blood pressure and the early transient incapacitation (ETI) and a causal relationship has been suggested, the extent to which hypotension precipitates the occurrence of the behavioral deficits remains uncertain. The present experiments investigated both radiogenic blood pressure and performance changes in a strain of rat bred for hypertension (spontaneously hypertensive rat: SHR) in order to determine if high blood pressure might attenuate ETI. Although male SHRs experienced a severe ETI and a drop in blood pressure, much of the data is inconsistent with the hypothesis that hypotension causes performance decrements. In an additional series of studies, blood volume and serum chemistry data were analyzed. Male SHRs were significantly higher than normotensive controls on several blood chemistry determinations. Exposure to ionizing radiation, more often than not, enhanced these differences. These results could not be explained on the basis of radiogenic blood volume fluctuations

MO-D-BRD-03: Radiobiology and Commissioning of Electronic Brachytherapy for IORT

Energy Technology Data Exchange (ETDEWEB)

Zhang, J. [Oregon Health & Science Univ (United States)

2015-06-15

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014, a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic

Simple preparation of thin CR-39 detectors for alpha-particle radiobiological experiments

International Nuclear Information System (INIS)

Chan, K.F.; Lau, B.M.F.; Nikezic, D.; Tse, A.K.W.; Fong, W.F.; Yu, K.N.

2007-01-01

Alpha-particle radiobiological experiments involve irradiating cells with alpha particles and require accurate positions where the alpha particles hit the cells. In the present work, we prepared thin CR-39 detectors from commercially available CR-39 SSNTDs with a thickness of 100 μm by etching them in 1 N NaOH/ethanol at 40 deg. C to below 20 μm. The desired final thickness was achieved within ∼8 h. Such etching conditions can provide relatively small roughness of the detector as revealed by atomic force microscope, and thus provide transparent detectors for radiobiological experiments. UV radiation was employed to shorten track formation time on these thin CR-39 detectors. After exposure to UV light (UVA + B radiation) for 2-3 h with doses from 259 to 389 W/cm 2 , 5 MeV alpha-particle tracks can be seen to develop on these CR-39 detectors clearly under the optical microscope within 2 h in 14 N KOH at 37 deg. C. As an example for practical use, custom-made petri dishes, with a hole drilled at the bottom and covered with a thin CR-39 detector, were used for culturing HeLa cells. The feasibility of using these thin CR-39 detectors is demonstrated by taking photographs of the cells and alpha-particle tracks together under the optical microscope, which can allow the hit positions on the cells by the alpha particles to be determined accurately

A model to describe potential effects of chemotherapy on critical radiobiological treatments

Science.gov (United States)

Rodríguez-Pérez, D.; Desco, M. M.; Antoranz, J. C.

2016-08-01

Although chemo- and radiotherapy can annihilate tumors on their own. they are also used in coadjuvancy: improving local effects of radiotherapy using chemotherapy as a radiosensit.izer. The effects of radiotherapy are well described by current radiobiological models. The goal of this work is to describe a discrete radiotherapy model, that has been previously used describe high radiation dose response as well as unusual radio-responses of some types of tumors (e.g. prostate cancer), to obtain a model of chemo+radiotherapy that can describe how the outcome of their combination is a more efficient removal of the tumor. Our hypothesis is that, although both treatments haven different mechanisms, both affect similar key points of cell metabolism and regulation, that lead to cellular death. Hence, we will consider a discrete model where chemotherapy may affect a fraction of the same targets destroyed by radiotherapy. Although radiotherapy reaches all cells equally, chemotherapy diffuses through a tumor attaining lower concentration in its center and higher in its surface. With our simulations we study the enhanced effect of combined therapy treatment and how it depends on the tissue critical parameters (the parameters of the lion-extensive radiobiological model), the number of “targets” aimed at by chemotherapy, and the concentration and diffusion rate of the drug inside the tumor. The results show that an equivalent, cliemo-radio-dose can be computed that allows the prediction of the lower radiation dose that causes the same effect than a radio-only treatment.

Radiobiological Determination of Dose Escalation and Normal Tissue Toxicity in Definitive Chemoradiation Therapy for Esophageal Cancer

Energy Technology Data Exchange (ETDEWEB)

Warren, Samantha, E-mail: Samantha.warren@oncology.ox.ac.uk [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom); Partridge, Mike [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom); Carrington, Rhys [Velindre Cancer Centre, Velindre Hospital, Cardiff (United Kingdom); Hurt, Chris [Wales Cancer Trials Unit, School of Medicine, Heath Park, Cardiff (United Kingdom); Crosby, Thomas [Velindre Cancer Centre, Velindre Hospital, Cardiff (United Kingdom); Hawkins, Maria A. [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom)

2014-10-01

Purpose: This study investigated the trade-off in tumor coverage and organ-at-risk sparing when applying dose escalation for concurrent chemoradiation therapy (CRT) of mid-esophageal cancer, using radiobiological modeling to estimate local control and normal tissue toxicity. Methods and Materials: Twenty-one patients with mid-esophageal cancer were selected from the SCOPE1 database (International Standard Randomised Controlled Trials number 47718479), with a mean planning target volume (PTV) of 327 cm{sup 3}. A boost volume, PTV2 (GTV + 0.5 cm margin), was created. Radiobiological modeling of tumor control probability (TCP) estimated the dose required for a clinically significant (+20%) increase in local control as 62.5 Gy/25 fractions. A RapidArc (RA) plan with a simultaneously integrated boost (SIB) to PTV2 (RA{sub 62.5}) was compared to a standard dose plan of 50 Gy/25 fractions (RA{sub 50}). Dose-volume metrics and estimates of normal tissue complication probability (NTCP) for heart and lungs were compared. Results: Clinically acceptable dose escalation was feasible for 16 of 21 patients, with significant gains (>18%) in tumor control from 38.2% (RA{sub 50}) to 56.3% (RA{sub 62.5}), and only a small increase in predicted toxicity: median heart NTCP 4.4% (RA{sub 50}) versus 5.6% (RA{sub 62.5}) P<.001 and median lung NTCP 6.5% (RA{sub 50}) versus 7.5% (RA{sub 62.5}) P<.001. Conclusions: Dose escalation to the GTV to improve local control is possible when overlap between PTV and organ-at-risk (<8% heart volume and <2.5% lung volume overlap for this study) generates only negligible increase in lung or heart toxicity. These predictions from radiobiological modeling should be tested in future clinical trials.

Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

Energy Technology Data Exchange (ETDEWEB)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M. (Eindhoven Univ. of Technology (Netherlands))

1990-01-31

ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed.

Intermolecular effects on the radiogenic formation of electron-capture phosphorus-centered radicals. A single-crystal ESR study of diastereoisomeric precursors

International Nuclear Information System (INIS)

Aagaard, O.M.; Janssen, R.A.J.; de Waal, B.F.M.; Buck, H.M.

1990-01-01

ESR experiments on X-irradiated single crystals of the 2R,4S,5R and 2S,4S,5R diastereoisomers of 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide reveal that the yield of radiogenic electron-capture reactions in the solid state strongly depends on intermolecular interactions in the crystal. In the present case a high yield of P-Cl three-electron-bond phosphoranyl radical anions is found in crystals of the 2R,4S,5R isomer, whereas no radical formation can be detected for the 2S,4S,5R isomer. An analysis of nonbonded interactions with neighboring molecules reveals that the geometry relaxation necessary for the radical stabilization is easily accommodated in crystals of the 2R,4S,SR isomer but not in the 2S,4S,5R isomer, explaining the observed difference in electron-capture efficiency. Experiments on radical formation in a MeTHF host matrix give further insight into the importance of the environment on radiogenic radical formation. The possible concurrent effect of the matrix on the electronic configuration and spin density distribution of the resulting phosphoranyl radical is discussed

Radiological and Environmental Research Division, Center for Human Radiobiology. Annual report, July 1980-June 1981. [Lead abstract

Energy Technology Data Exchange (ETDEWEB)

1982-03-01

Separate abstracts were prepared for the 22 papers of this annual report of the Center for Human Radiobiology. Abstracts were not written for 2 appendices which contain data on the exposure and radium-induced malignancies of 2259 persons whose radium content has been determined at least once. (KRM)

Radiobiological experiments with heavy ions

International Nuclear Information System (INIS)

Kraft, G.

1988-11-01

In experiments, performed at the Unilac, Bevalac, and Ganil a large body of radiobiological data, cross sections for cell inactivation and mutation, induction of both, chromosome aberrations, and strand breaks of DNA have been measured for different atomic numbers, from helium (Z=2) to uranium (Z=92), and at an LET range from 10 to 16000 keV/μm. These data exhibit a common feature: At LET values below 100 keV/μm all data points of one specific effect form one single curve as a function of LET, independent from the atomic number of the ion. In this LET range, the biological effects are independ from the particle energy or track structure and depend only on the energy transfer. Therefore, LET is a good parameter in this regime. For LET values greater than 100 keV/μm, the curves for the different ions separate from the common curve in order of increasing atomic numbers. In this regime LET is no longer a good parameter and the physical parameters of the formation of particle tracks are important. The similarity of the σ-LET curves for different endpoints shows that the 'hook-structure' is produced by physical and chemical effects which occur before the biologically relevant lesions are formed. For this part of the reaction chain only a very limited amount of data are available. (orig./MG)

Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

Czech Academy of Sciences Publication Activity Database

Adjei, D.; Ayele, M. G.; Wachulak, P.; Bartnik, A.; Wegrzynski, L.; Fiedorowicz, H.; Vyšín, Luděk; Wiechec, A.; Lekki, J.; Kwiatek, W. M.; Pina, L.; Davídková, Marie; Juha, Libor

2015-01-01

Roč. 364, Dec (2015), s. 27-32 ISSN 0168-583X R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GA13-28721S EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Institutional support: RVO:68378271 ; RVO:61389005 Keywords : laser-produced plasma * soft X-rays * radiobiology * gas puff target * water window Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.389, year: 2015

Repairable-conditionally repairable damage model based on dual Poisson processes.

Science.gov (United States)

Lind, B K; Persson, L M; Edgren, M R; Hedlöf, I; Brahme, A

2003-09-01

The advent of intensity-modulated radiation therapy makes it increasingly important to model the response accurately when large volumes of normal tissues are irradiated by controlled graded dose distributions aimed at maximizing tumor cure and minimizing normal tissue toxicity. The cell survival model proposed here is very useful and flexible for accurate description of the response of healthy tissues as well as tumors in classical and truly radiobiologically optimized radiation therapy. The repairable-conditionally repairable (RCR) model distinguishes between two different types of damage, namely the potentially repairable, which may also be lethal, i.e. if unrepaired or misrepaired, and the conditionally repairable, which may be repaired or may lead to apoptosis if it has not been repaired correctly. When potentially repairable damage is being repaired, for example by nonhomologous end joining, conditionally repairable damage may require in addition a high-fidelity correction by homologous repair. The induction of both types of damage is assumed to be described by Poisson statistics. The resultant cell survival expression has the unique ability to fit most experimental data well at low doses (the initial hypersensitive range), intermediate doses (on the shoulder of the survival curve), and high doses (on the quasi-exponential region of the survival curve). The complete Poisson expression can be approximated well by a simple bi-exponential cell survival expression, S(D) = e(-aD) + bDe(-cD), where the first term describes the survival of undamaged cells and the last term represents survival after complete repair of sublethal damage. The bi-exponential expression makes it easy to derive D(0), D(q), n and alpha, beta values to facilitate comparison with classical cell survival models.

The crystallochemical factor of strong keeping of radiogenic 187Os in the structure of rhenium-bearing molybdenites

International Nuclear Information System (INIS)

Val'ter, A.A.; Pisanskij, A.I.; Podberezskaya, N.V.

2007-01-01

To understand the possible cause of the strong keeping of radiogenic Os in comparison with initial Re in the molybdenite structure, we compare the cation positions in MoS 2 , ReS 2 , and OsS 2 and the geometry of 'empty' octahedra of the molybdenite structure. The similarity of 'empty' octahedra of MoS 2 and the Os environment in OsS 2 is determined. So, one can assume that knock-on atoms of 187 Os can be fixed in 'empty' octahedra by recoiling or the later thermal action

SU-G-TeP3-11: Radiobiological-Cum-Dosimetric Quality Assurance of Complex Radiotherapy Plans

Energy Technology Data Exchange (ETDEWEB)

Paudel, N; Narayanasamy, G; Zhang, X; Penagaricano, J; Morrill, S [University of Arkansas for Medical Sciences, Little Rock, AR (United States); Mavroidis, P [University North Carolina, Chapel Hill, NC (United States); Pyakuryal, A [National Cancer Institute, Rockville, MD (United States); Han, E [UT MD Anderson Cancer Center, Houston, TX (United States); Liang, X [University of Florida Health Proton Therapy Institute, Jacksonville, FL (United States); Kim, D [Kyung Hee University Hospital, Seol (Korea, Republic of)

2016-06-15

Purpose: Dosimetric gamma-analysis used for QA of complex radiotherapy plans tests the dosimetric equivalence of a delivered plan with the treatment planning system (TPS) optimized plan. It does not examine whether a dosimetric difference results in any radiobiological difference. This study introduces a method to test the radiobiological and dosimetric equivalence between a delivered and the TPS optimized plan. Methods: Six head and neck and seven lung cancer VMAT or IMRT plans optimized for patient treatment were calculated and delivered to an ArcCheck phantom. ArcCheck measured dose distributions were compared with the TPS calculated dose distributions using a 2-D gamma-analysis. Dose volume histograms (DVHs) for various patient structures were obtained by using measured data in 3DVH software and compared against the TPS calculated DVHs using 3-D gamma analysis. DVH data were used in the Poisson model to calculate tumor control probability (TCP) for the treatment targets and in the sigmoid dose response model to calculate normal tissue complication probability (NTCP) for the normal structures. Results: Two-D and three-D gamma passing rates among six H&N patient plans differed by 0 to 2.7% and among seven lung plans by 0.1 to 4.5%. Average ± SD TCPs based on measurement and TPS were 0.665±0.018 and 0.674±0.044 for H&N, and 0.791±0.027 and 0.733±0.031 for lung plans, respectively. Differences in NTCPs were usually negligible. The differences in dosimetric results, TCPs and NTCPs were insignificant. Conclusion: The 2-D and 3-D gamma-analysis based agreement between measured and planned dose distributions may indicate their dosimetric equivalence. Small and insignificant differences in TCPs and NTCPs based on measured and planned dose distributions indicate the radiobiological equivalence between the measured and optimized plans. However, patient plans showing larger differences between 2-D and 3-D gamma-analysis can help us make a more definite conclusion

Removal of radiation damage by subpopulations of plateau-phase Chinese hamster ovary cells

International Nuclear Information System (INIS)

Nelson, J.M.; Metting, N.F.; Braby, L.A.; Roesch, W.C.

1987-01-01

Specific cellular radiobiology studies are often required to test aspects of the mathematical models developed in the Radiation Dosimetry program. These studies are designed to determine whether specific mathematical expressions, which characterize the expected effect of biochemical mechanisms on observable biological responses, are consistent with the behavior of selected cell lines. Since these tests place stringent requirements on the cellular system, special techniques and culture conditions are required to minimize biological variability. The use of specialized cell populations is providing data on the extent of repair following low doses, and on the changes in the types of damage that can be repaired as the cell progresses toward mitosis. The stationary-phase Chinese hamster ovary (CHO) cells are composed primarily of G(1)-phase cells (83%), with the remainder comprising both G(2) and S phases. Removal of radiation damage by cells was studied in split-dose experiments. To date, we have observed no significant differences in cellular repair rate. This suggests, therefore, that each of the repair processes found in stationary-phase cells is cell-age independent. However, cellular radiation sensitivity does change rapidly and considerably as the cells progress from one phase to the next through the cell cycle. Since the rate of damage removal appears invariant, the change in survival must reflect the efficiency of producing that damage. The experimental data suggest that production of one or another sort of damage probably dominates during specific phases of the cell cycle, while the capacity for removal of all types of damage remains relatively constant

Characterizing genetic syndromes involved in cancer and radiogenic cancer risk

International Nuclear Information System (INIS)

Unrau, P.; Doerffer, K.

1998-01-01

The COG project 2806A (1995), reviewed the On-line Mendelian Inheritance in Man (OMIM) database of genetic syndromes to identify those syndromes, genes, and DNA sequences implicated in some way in the cancer process, and especially in radiogenic cancer risk. The current report describes a recent update of the survey in light of two years of further progress in the Human Genome project, and is intended to supply a comprehensive list of those genetic syndromes, genes, DNA sequences and map locations that define genes likely to be involved in cancer risk. Of the 8203 syndromes in OMIM in 1997 June, 814 are associated, even if marginally, with cancer. Of the 814 syndromes so linked, 672 have been mapped to a chromosome, and 476 have been mapped to a chromosome and had a DNA sequence associated with their messenger RNA (or cDNA) sequences. In addition, 35 syndromes have sequences not associated with map locations, and the remaining 107 have neither been mapped nor sequenced. We supply the list of the various genetic syndromes sorted by chromosome location and by OMIM descriptor, together with all the associated but unmapped and unsequenced syndromes. (author)

Characterizing genetic syndromes involved in cancer and radiogenic cancer risk

Energy Technology Data Exchange (ETDEWEB)

Unrau, P; Doerffer, K

1998-01-01

The COG project 2806A (1995), reviewed the On-line Mendelian Inheritance in Man (OMIM) database of genetic syndromes to identify those syndromes, genes, and DNA sequences implicated in some way in the cancer process, and especially in radiogenic cancer risk. The current report describes a recent update of the survey in light of two years of further progress in the Human Genome project, and is intended to supply a comprehensive list of those genetic syndromes, genes, DNA sequences and map locations that define genes likely to be involved in cancer risk. Of the 8203 syndromes in OMIM in 1997 June, 814 are associated, even if marginally, with cancer. Of the 814 syndromes so linked, 672 have been mapped to a chromosome, and 476 have been mapped to a chromosome and had a DNA sequence associated with their messenger RNA (or cDNA) sequences. In addition, 35 syndromes have sequences not associated with map locations, and the remaining 107 have neither been mapped nor sequenced. We supply the list of the various genetic syndromes sorted by chromosome location and by OMIM descriptor, together with all the associated but unmapped and unsequenced syndromes. (author) 1 tab., 4 figs.

Radiobiological research for improving cancer therapy in India: rationale, problems and prospects

International Nuclear Information System (INIS)

Kalia, Vijay K.; Shobha, A.G.; KaIia, Anita; Saxena, Amit

2012-01-01

Cancer is emerging as a very important health hazard in India. According to recent studies by the Indian Council of Medical Research, about 2.25 million patients are presently suffering from different types of cancer in India. Approximately one million new cases are diagnosed, and nearly 0.3 million deaths occur every year on account of this disease. About 2/3rd of the cancers are at an advanced stage at the time of diagnosis. However, the allocation of funds for healthcare in India to support the research efforts for developing more potent radio-chemotherapy protocols for cancer treatment is too little. Studies by the W.H.O. have estimated that less developed countries including India use less than 5% of world resources destined for cancer control. It follows from the above discussions that it is imperative to further encourage and diversify the radiobiological research in India. This can be achieved by creating radiobiological research facilities, mainly in all the cancer centers and post graduate medical institutions, and further expanding the upcoming laboratories in the universities such as Bikaner. Collaborative research programs between laboratories at different centers could facilitate systematic evaluation of various pharmacological agents and neutraceuticals for potential application for treatment of different cancers. Our studies on combination of radiation with temozolomide and certain adjuvants with selective effects on brain tumour cells will be very briefly discussed in this presentation. Finally the possible administrative set up and multi dimensional collaborations for cost effective utilization of existing resources to further augment radiation biology research will also be discussed

A model to describe potential effects of chemotherapy on critical radiobiological treatments

International Nuclear Information System (INIS)

Rodríguez-Pérez, D.; Desco, M.M.; Antoranz, J.C.

2016-01-01

Although chemo- and radiotherapy can annihilate tumors on their own. they are also used in coadjuvancy: improving local effects of radiotherapy using chemotherapy as a radiosensit.izer. The effects of radiotherapy are well described by current radiobiological models. The goal of this work is to describe a discrete radiotherapy model, that has been previously used describe high radiation dose response as well as unusual radio-responses of some types of tumors (e.g. prostate cancer), to obtain a model of chemo+radiotherapy that can describe how the outcome of their combination is a more efficient removal of the tumor. Our hypothesis is that, although both treatments haven different mechanisms, both affect similar key points of cell metabolism and regulation, that lead to cellular death. Hence, we will consider a discrete model where chemotherapy may affect a fraction of the same targets destroyed by radiotherapy. Although radiotherapy reaches all cells equally, chemotherapy diffuses through a tumor attaining lower concentration in its center and higher in its surface. With our simulations we study the enhanced effect of combined therapy treatment and how it depends on the tissue critical parameters (the parameters of the lion-extensive radiobiological model), the number of “targets” aimed at by chemotherapy, and the concentration and diffusion rate of the drug inside the tumor. The results show that an equivalent, cliemo-radio-dose can be computed that allows the prediction of the lower radiation dose that causes the same effect than a radio-only treatment. (paper)

Radiobiological research on carnation chimerae Dianthus Caryophyllus L

International Nuclear Information System (INIS)

Pereau-Leroy, Pierre.

1975-01-01

A radiobiological study of periclinal carnation chimerae is carried out by subjecting whole plants and cuttings at different physiological stages to cobalt 60 gamma radiation under different dose and dose rate conditions. The effects of these treatments are observed during cultivation of the treated plants and by microscopic examination of irradiated meristem sections. The destruction of meristem cells in proportions varying with the irradiation conditions leads to structural changes in the chimerae; the more frequent change is the formation of genetically homogeneous stalks from different genotypes existing in the irradiated plant. Treatment by ionizing radiations is thus a practical means of detecting periclinical chimerae which, as in the case of carnations, are very common in plants grown by vegetative propagation. However since more than two independent meristem cell groups are usually present it is not possible by this method alone to define the distribution of the differentent genotypes in these groups; additional genetic studies or cell labelling such as chlorophyll or genoma mutations are then necessary [fr

Interface between technical physics and technological irradiation with reference to applications in vegetal and animal radiobiology

International Nuclear Information System (INIS)

Peteu, G.; Opris, M.

1994-01-01

The main goals of vegetal and animal radiobiology in a specific correlation with technical physics are the stimulation of germination and induced mutations; vegetal and animal food conservation, sterilization techniques, and modifications in the radiosensitivity of biological systems. The existing correlation between the effects of exposed and absorbed doses, and the behaviour of the 'microflora' (microbes, fungi), are discussed. (Author)

Role of endothelium in radiation-induced normal tissue damages

International Nuclear Information System (INIS)

Milliat, F.

2007-05-01

More than half of cancers are treated with radiation therapy alone or in combination with surgery and/or chemotherapy. The goal of radiation therapy is to deliver enough ionising radiation to destroy cancer cells without exceeding the level that the surrounding healthy cells can tolerate. Unfortunately, radiation-induced normal tissue injury is still a dose limiting factor in the treatment of cancer with radiotherapy. The knowledge of normal tissue radiobiology is needed to determine molecular mechanisms involved in normal tissue pathogenic pathways in order to identify therapeutic targets and develop strategies to prevent and /or reduce side effects of radiation therapy. The endothelium is known to play a critical role in radiation-induced injury. Our work shows that endothelial cells promote vascular smooth muscle cell proliferation, migration and fibro-genic phenotype after irradiation. Moreover, we demonstrate for the first time the importance of PAI-1 in radiation-induced normal tissue damage suggesting that PAI-1 may represent a molecular target to limit injury following radiotherapy. We describe a new role for the TGF-b/Smad pathway in the pathogenesis of radiation-induced damages. TGF-b/Smad pathway is involved in the fibro-genic phenotype of VSMC induced by irradiated EC as well as in the radiation-induced PAI-1 expression in endothelial cells. (author)

GBD 2000 - Proceedings of the 4. annual meeting of 'Gesellschaft fuer Biologische Strahlenforschung'; GBS 2000 - Proceedings der 4. Jahrestagung der Gesellschaft fuer Biologische Strahlenforschung

Energy Technology Data Exchange (ETDEWEB)

Eckardt-Schupp, F.; Ahne, F.; Kistler, M. (eds.) [Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany). Inst. fuer Strahlenbiologie

2000-07-01

The headings of the meeting were as follows: Radiation chemistry and micro beam irradiation; DNA radiation damage and biological models; DNA repair; genetic radiation effects; radiation effects and stress effects on gene expression; cellular radiobiology; radiobiology of tumors and normal tissues; epidemiology.

GBD 2000 - Proceedings of the 4. annual meeting of 'Gesellschaft fuer Biologische Strahlenforschung'

International Nuclear Information System (INIS)

Eckardt-Schupp, F.; Ahne, F.; Kistler, M.

2000-01-01

The headings of the meeting were as follows: Radiation chemistry and micro beam irradiation; DNA radiation damage and biological models; DNA repair; genetic radiation effects; radiation effects and stress effects on gene expression; cellular radiobiology; radiobiology of tumors and normal tissues; epidemiology

Low energy electron-driven damage in biomolecules

International Nuclear Information System (INIS)

Sanche, L.

2005-01-01

The damage induced by the impact of low energy electrons (LEE) on biomolecules is reviewed from a radiobiological perspective with emphasis on transient anion formation. The major type of experiments, which measure the yields of fragments produced as a function of incident electron energy (0.1 - 30 eV), are briefly described. Theoretical advances are also summarized. Several examples are presented from the results of recent experiments performed in the gas-phase and on bio-molecular films bombarded with LEE under ultra-high vacuum conditions. These include the results obtained from DNA films and those obtained from the fragmentation of elementary components of the DNA molecule (i.e., the bases, sugar and phosphate group analogs and oligonucleotides) and of proteins (e.g. amino acids). By comparing the results from different experiments and theory, it is possible to determine fundamental mechanisms that are involved in the dissociation of the biomolecules and the production of single- and double-strand breaks in DNA. Below 15 eV, electron resonances (i.e., the formation of transient anions) play a dominant role in the fragmentation of all biomolecules investigated. These transient anions fragment molecules by decaying into dissociative electronically excited states or by dissociating into a stable anion and a neutral radical. These fragments can initiate further reactions within large biomolecules or with nearby molecules and thus cause more complex chemical damage. Dissociation of a transient anion within DNA may occur by direct electron attachment at the location of dissociation or by electron transfer from another subunit. Damage to DNA is dependent on the molecular environment, topology, type of counter ion, sequence context and chemical modifications. (author)

Primary radiation damage and disturbance in cell divisions

International Nuclear Information System (INIS)

Kim, Jin Kyu; Lee, Yun-Jong; Kim, Jae-Hun; Petin, Vladislav G.; Nili, Mohammad

2008-01-01

Survived cells from a homogeneous population exposed to ionizing radiation form various colonies of different sizes and morphology on a solid nutrient medium, which appear at different time intervals after irradiation. Such a phenomenon agrees well with the modern theory of microdosimetry and classical hit-and-target models of radiobiology. According to the hit-principle, individual cells exposed to the same dose of radiation are damaged in different manners. It means that the survived cells can differ in the content of sublethal damage (hits) produced by the energy absorbed into the cell and which is not enough to give rise to effective radiation damage which is responsible for cell killing or inactivation. In diploid yeast cells, the growth rate of cells from 250 colonies of various sizes appeared at different time intervals after irradiation with 600 Gy of gamma radiation from a 60 Co isotopic source was analyzed. The survival rate after irradiation was 20%. Based on the analyses results, it was possible to categorize the clones grown from irradiated cells according to the number of sub-lesions from 1 to 4. The clones with various numbers of sub-lesions were shown to be different in their viability, radiosensitivity, sensitivity to environmental conditions, and the frequency of recombination and respiratory deficient mutations. Cells from unstable clones exhibited an enhanced radiosensitivity, and an increased portion of morphologically changed cells, nonviable cells and respiration mutants, as well. The degree of expression of the foregoing effects was higher if the number of primary sublethal lesions was greater in the originally irradiated cell. Disturbance in cell division can be characterized by cell inactivation or incorrect distribution of mitochondria between daughter cells. Thus, the suggested methodology of identification of cells with a definite number of primary sublethal lesions will promote further elucidation of the nature of primary radiation

Direct evaluation of radiobiological parameters from clinical data in the case of ion beam therapy: an alternative approach to the relative biological effectiveness

International Nuclear Information System (INIS)

Cometto, A; Russo, G; Giordanengo, S; Marchetto, F; Cirio, R; Attili, A; Bourhaleb, F; Milian, F M

2014-01-01

The relative biological effectiveness (RBE) concept is commonly used in treatment planning for ion beam therapy. Whether models based on in vitro/in vivo RBE data can be used to predict human response to treatments is an open issue. In this work an alternative method, based on an effective radiobiological parameterization directly derived from clinical data, is presented. The method has been applied to the analysis of prostate cancer trials with protons and carbon ions. Prostate cancer trials with proton and carbon ion beams reporting 5 year-local control (LC5) and grade 2 (G2) or higher genitourinary toxicity rates (TOX) were selected from literature to test the method. Treatment simulations were performed on a representative subset of patients to produce dose and linear energy transfer distribution, which were used as explicative physical variables for the radiobiological modelling. Two models were taken into consideration: the microdosimetric kinetic model (MKM) and a linear model (LM). The radiobiological parameters of the LM and MKM were obtained by coupling them with the tumor control probability and normal tissue complication probability models to fit the LC5 and TOX data through likelihood maximization. The model ranking was based on the Akaike information criterion. Results showed large confidence intervals due to the limited variety of available treatment schedules. RBE values, such as RBE = 1.1 for protons in the treated volume, were derived as a by-product of the method, showing a consistency with current approaches. Carbon ion RBE values were also derived, showing lower values than those assumed for the original treatment planning in the target region, whereas higher values were found in the bladder. Most importantly, this work shows the possibility to infer the radiobiological parametrization for proton and carbon ion treatment directly from clinical data. (paper)

Preliminary results in the application of radiobiological models in the evaluation of radiotherapy plans

International Nuclear Information System (INIS)

Calderon, Carlos; Napoles, Mysleidis; Asencion, Yudy; Yanes, Yahima; Alfonso, Rodolfo; Gonzalez, Joaquin

2009-01-01

Notwithstanding the limitations of radiobiological models in the clinical application, its use is becoming more widespread in order to quantitatively assess the bioequivalence of different regimens of irradiation, the effective comparison between different treatment plans by estimating the probability tumor control (TCP) or the probability of normal tissue complication (NTCP), or solve problems, such as the rescheduling of treatments in case of failure. The response to irradiation in the tissues at risk (OARS) depends on factors such as volume irradiated or its organizational structure and behavior can vary for a given dose distribution. Another important aspect is the sensitivity of these models to the variation of parameters (α, α / β, proliferation, clonogenic density, etc.) Measuring the difference between-subjects. Commercial planning systems do not always possible to estimate the biological response of the OARS and CTV. This study presents an assessment of the results of two applications (free ware) and Albireo Target BIOPLAN Cygnus X1 that calculate statistical parameters of the DVH: equivalent uniform dose (EUD), equivalent biological dose (BED), medium dose and other to estimate TCP (Poisson model) and NTCP (Lyman-Kutcker models-Burman and relative seriality) for the calculation of the objective functions: the probability of uncomplicated control (UTCP) based on generalized EUD (f). We studied the response of both systems to the variation of relevant radiobiological parameters and the shape of the DVH. (Author)

Preliminary results in the application of radiobiological models in the evaluation of radiotherapy plans

International Nuclear Information System (INIS)

Calderon, Carlos; Napoles, Mysleidis; Asencion, Yudy; Yanes, Yahima; Alfonso, Rodolfo; Gonzalez Joaquin

2009-01-01

Notwithstanding the limitations of radiobiological models in the clinical application, its use is becoming more widespread in order to quantitatively assess the bioequivalence of different regimens of irradiation, the effective comparison between different treatment plans by estimating the probability tumor control (TCP) or the probability of normal tissue complication (NTCP), or solve problems, such as the rescheduling of treatments in case of failure. The response to irradiation in the tissues at risk (OARS) depends on factors such as volume irradiated or its organizational structure and behavior can vary for a given dose distribution. Another important aspect is the sensitivity of these models to the variation of parameters (a, a / β, proliferation, clonogenic density, etc.) Measuring the difference between-subjects. Commercial planning systems do not always possible to estimate the biological response of the OARS and CTV. This study presents an assessment of the results of two applications (free ware) and Albireo Target BIOPLAN Cygnus X1 that calculate statistical parameters of the DVH: equivalent uniform dose (EUD), equivalent biological dose (BED), medium dose and other to estimate TCP (Poisson model) and NTCP (Lyman-models-Kutcker Burman and relative seriality) for the calculation of the objective functions: the probability of uncomplicated control (UTCP) based on generalized EUD (f). We studied the response of both systems to the variation of relevant radiobiological parameters and the shape of the DVH. (author)

Late radiation-induced heart disease after radiotherapy. Clinical importance, radiobiological mechanisms and strategies of prevention

International Nuclear Information System (INIS)

Andratschke, Nicolaus; Maurer, Jean; Molls, Michael; Trott, Klaus-Ruediger

2011-01-01

The clinical importance of radiation-induced heart disease, in particular in post-operative radiotherapy of breast cancer patients, has been recognised only recently. There is general agreement, that a co-ordinated research effort would be needed to explore all the potential strategies of how to reduce the late risk of radiation-induced heart disease in radiotherapy. This approach would be based, on one hand, on a comprehensive understanding of the radiobiological mechanisms of radiation-induced heart disease after radiotherapy which would require large-scale long-term animal experiments with high precision local heart irradiation. On the other hand - in close co-operation with mechanistic in vivo research studies - clinical studies in patients need to determine the influence of dose distribution in the heart on the risk of radiation-induced heart disease. The aim of these clinical studies would be to identify the critical structures within the organ which need to be spared and their radiation sensitivity as well as a potential volume and dose effect. The results of the mechanistic studies might also provide concepts of how to modify the gradual progression of radiation damage in the heart by drugs or biological molecules. The results of the studies in patients would need to also incorporate detailed dosimetric and imaging studies in order to develop early indicators of impending radiation-induced heart disease which would be a pre-condition to develop sound criteria for treatment plan optimisation.

Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate.

Science.gov (United States)

Beyreuther, Elke; Karsch, Leonhard; Laschinsky, Lydia; Leßmann, Elisabeth; Naumburger, Doreen; Oppelt, Melanie; Richter, Christian; Schürer, Michael; Woithe, Julia; Pawelke, Jörg

2015-08-01

In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery. The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity. The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation. The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.

Radiobiological effect of different irradiation fractionated regimens in human brain glioma

International Nuclear Information System (INIS)

Gai Xue; Yang Weizhi; Gao Li; Jiang Heng; Wang Mianrong; Shi Huizhen

2010-01-01

Objective: To evaluate the radiobiological effect of different irradiation fractionated regimens in human glioma cells (BT 325 cell line). Methods: The xenografts in Balb/c-nude mice were irradiated with different single and fractionated regimens. The single fraction dose was 10, 20, 30, 40 and 60 Gy, respectively. The fractionated regimens were 2 Gy x 5 fractions ( irradiated every day), and 3 Gy x 3 fractions (irradiated every other day), 3 Gy x 5 fractions (irradiated every day) and 4 Gy x 3 fractions (irradiated every other day), with total doses of 125 Gy, 114 Gy, 126 Gy and 112 Gy, respectively. The growth curve was used to evaluate the tumor doubling time. clonogenic assays was performed to draw the cell survival curve and analyze the radiobiological parameters with doses of 1, 2, 4, 6, 8 and 10 Gy. T 1/2 was measured by comet assay. Results: Tumor regression were not observed by single fraction irradiation, 2 Gy x 5 fractions and 3 Gy x 3 fractions irradiation regimens. The tumor regress was more significant with the increas of fraction dose. The 4 Gy x 3 fractions inhibited tumor more though not curing tumor. The cell doubling time of the BT 325 cell was 30. 16 h and the tumor doubling time of the xenograft was 43 days.When fitted with L-Q model, α was 0. 36 Gy -1 and β was 0. 057 Gy -2 . When fitted with the single-hit multi target model, D 0 was 1. 394 Gy, Dq was 2. 127 Gy and SF 2 was 0.714, respectively. The T 1/2 was 9.999 min. Conclusions: Glioma is a radioresistant tumor. Increase of the fraction dose improves recent effect.Further study is needed to control the tumor stem cells. (authors)

Automated Sample Preparation for Radiogenic and Non-Traditional Metal Isotopes: Removing an Analytical Barrier for High Sample Throughput

Science.gov (United States)

Field, M. Paul; Romaniello, Stephen; Gordon, Gwyneth W.; Anbar, Ariel D.; Herrmann, Achim; Martinez-Boti, Miguel A.; Anagnostou, Eleni; Foster, Gavin L.

2014-05-01

MC-ICP-MS has dramatically improved the analytical throughput for high-precision radiogenic and non-traditional isotope ratio measurements, compared to TIMS. The generation of large data sets, however, remains hampered by tedious manual drip chromatography required for sample purification. A new, automated chromatography system reduces the laboratory bottle neck and expands the utility of high-precision isotope analyses in applications where large data sets are required: geochemistry, forensic anthropology, nuclear forensics, medical research and food authentication. We have developed protocols to automate ion exchange purification for several isotopic systems (B, Ca, Fe, Cu, Zn, Sr, Cd, Pb and U) using the new prepFAST-MC™ (ESI, Nebraska, Omaha). The system is not only inert (all-flouropolymer flow paths), but is also very flexible and can easily facilitate different resins, samples, and reagent types. When programmed, precise and accurate user defined volumes and flow rates are implemented to automatically load samples, wash the column, condition the column and elute fractions. Unattended, the automated, low-pressure ion exchange chromatography system can process up to 60 samples overnight. Excellent reproducibility, reliability, recovery, with low blank and carry over for samples in a variety of different matrices, have been demonstrated to give accurate and precise isotopic ratios within analytical error for several isotopic systems (B, Ca, Fe, Cu, Zn, Sr, Cd, Pb and U). This illustrates the potential of the new prepFAST-MC™ (ESI, Nebraska, Omaha) as a powerful tool in radiogenic and non-traditional isotope research.

Mechanistic explanations for the elevated susceptibility of the perinatal thyroid gland to radiogenic cancer

International Nuclear Information System (INIS)

Sikov, M.R.; Mahlum, D.D.; Dagle, G.E.; Daniel, J.L.; Goldman, M.

1988-01-01

Results from laboratory experiments and epidemiologic studies suggest that the thyroid gland is more susceptible to radiogenic cancer during the late prenatal or early postnatal periods than in adulthood. We have evaluated several endpoints in the course of experiments in which rats, at ages ranging from late gestation to adulthood, were exposed to graded doses of 131 I. Morphologic responses at sequential times after exposure were evaluated in one series of experiments. Cell death, degeneration, fibrosis of the gland were the predominant findings after exposure of weanlings or adults, but inhibition of thyroid growth and differentiation was the characteristic change after perinatal exposure. The degree of maturation and dosimetric factors are involved in this differential morphologic response, and also result in age-dependent physiologic differences in the postexposure period

Noble Gases in Alpine Gold: U/Th-He Dating and Excesses of Radiogenic He and AR

Science.gov (United States)

Eugster, O.; Hofmann, B.; Krahenbuhl, U.; Neuenschwander, J.

1992-07-01

Gold precipitates in hydrothermal fluids along with other heavy elements, such as Ag and Pt. In order to explore the possibility of dating the formation of gold we determined the concentrations of U, Th, and their decay product ^4He, as well as the K and ^40Ar concentrations in vein-type gold and in placer gold samples. The gold-quartz veins at Brusson in the south-western alps were formed approximately 32 Ma ago during an episode of tectonic uplift (Diamond, 1990). Alpine material was deposited as sediment layers in the region of central Switzerland and placer gold is thus relatively abundant in the rivers of the Napf area. We washed placer gold from the river Grosse Fontanne in 1990 and 1991. Placer gold that had been collected from the river Kruempelgraben in 1933 and a sample of vein-type free gold grown on quartz rock from the Brusson area (Val d'Ayas) have been obtained from the Museum of Natural History in Bern. Table 1 gives the results. Most of the ^4He is released above 1050 degrees C, that is when gold melts, indicating that gold is extremely well retentive for He. From the ^4He concentration of (269 +- 20) x 10^-8 cm^3 STP/g, (0.4 +- 0.1) ppm U, and (0.9 +- 0.3) ppm Th for vein-type gold we calculate a U/Th-He age of (36 +- 8)Ma. This age agrees within errors with the proposed age of 32 Ma. The data given in Table 1 show that all placer gold samples contain excesses of radiogenic ^4He and ^40Ar relative to the concentrations expected from the U/Th and K decay, respectively, if we assume a formation age of 32 Ma. The quartz sample is depleted in ^4He but strongly enriched in radiogenic ^40Ar. The excess of ^40Ar(sub)rad is easier to explain than that of ^4He. Vein-type gold and placer gold contain quartz inclusions (Schmid, 1973). The high ^40Ar(sub)rad content of quartz (Table 1) indicates that the ^40Ar(sub)rad excess of gold originates from quartz inclusions. Excess ^4He in gold must be of radiogenic origin. Taking ^20Ne and ^36Ar as a measure for the

The Nasa space radiation school, an excellent training in radiobiology and space radiation protection; La NASA space radiation summer school, une formation d'excellence en radiobiologie et radioprotection spatiale

Energy Technology Data Exchange (ETDEWEB)

Vogin, G. [Centre Alexis-Vautrin, 54 - Nancy (France)

2009-10-15

The astronauts have to spend more time in space and the colonization of the moon and Mars are in the cross hairs of international agencies. The cosmic radiation from which we are protected on ground by atmosphere and by the terrestrial magnetosphere (.4 mSv/year according to Who) become really threatening since 20 km altitude, delivering an average radiation dose of a therapeutic kind to astronauts with peaks related to solar events. It is composed in majority of hadrons: protons (85%) and heavy ions (13%), but also photons (2%) of high energy (GeV/n)). the incurred risks are multiple: early ones(cataract, central nervous system damages, whole body irradiation) but especially delayed ones (carcinogenesis). The astronauts radiation protection turns poor and the rate of death risk by cancer returning from a mission on Mars has been estimated at 5%. The Nasa created in 2004 a summer school aiming to awareness young researchers to the space radiobiology specificities. Areas concerned as follow: radioinduced DNA damage and repair, cell cycle, apoptosis, bystander effect, genome instability, neuro degeneration, delayed effects and carcinogenesis in relation with radiation exposure. (N.C.)

Evaluation of radiobiological effects in 3 distinct biological models

International Nuclear Information System (INIS)

Lemos, J.; Costa, P.; Cunha, L.; Metello, L.F.; Carvalho, A.P.; Vasconcelos, V.; Genesio, P.; Ponte, F.; Costa, P.S.; Crespo, P.

2015-01-01

Full text of publication follows. The present work aims at sharing the process of development of advanced biological models to study radiobiological effects. Recognizing several known limitations and difficulties of the current monolayer cellular models, as well as the increasing difficulties to use advanced biological models, our group has been developing advanced biological alternative models, namely three-dimensional cell cultures and a less explored animal model (the Zebra fish - Danio rerio - which allows the access to inter-generational data, while characterized by a great genetic homology towards the humans). These 3 models (monolayer cellular model, three-dimensional cell cultures and zebra fish) were externally irradiated with 100 mGy, 500 mGy or 1 Gy. The consequences of that irradiation were studied using cellular and molecular tests. Our previous experimental studies with 100 mGy external gamma irradiation of HepG2 monolayer cells showed a slight increase in the proliferation rate 24 h, 48 h and 72 h post irradiation. These results also pointed into the presence of certain bystander effects 72 h post irradiation, constituting the starting point for the need of a more accurate analysis realized with this work. At this stage, we continue focused on the acute biological effects. Obtained results, namely MTT and clonogenic assays for evaluating cellular metabolic activity and proliferation in the in vitro models, as well as proteomics for the evaluation of in vivo effects will be presented, discussed and explained. Several hypotheses will be presented and defended based on the facts previously demonstrated. This work aims at sharing the actual state and the results already available from this medium-term project, building the proof of the added value on applying these advanced models, while demonstrating the strongest and weakest points from all of them (so allowing the comparison between them and to base the subsequent choice for research groups starting

ON01210.Na (Ex-RAD® mitigates radiation damage through activation of the AKT pathway.

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Anthony D Kang

Full Text Available Development of radio-protective agents that are non-toxic is critical in light of ever increasing threats associated with proliferation of nuclear materials, terrorism and occupational risks associated with medical and space exploration. In this communication, we describe the discovery, characterization and mechanism of action of ON01210.Na, which effectively protects mouse and human bone marrow cells from radiation-induced damage both in vitro and in vivo. Our results show that treatment of normal fibroblasts with ON01210.Na before and after exposure to ionizing radiation provides dose dependent protection against radiation-induced damage. Treatment of mice with ON01210.Na prior to radiation exposure was found to result in a more rapid recovery of their hematopoietic system. The mechanistic studies described here show that ON01210.Na manifests its protective effects through the up-regulation of PI3-Kinase/AKT pathways in cells exposed to radiation. These results suggest that ON 01210.Na is a safe and effective radioprotectant and could be a novel agent for use in radiobiological disasters.

Radiobiology, biochemistry and radiation biophysics at CYLAB

International Nuclear Information System (INIS)

Ftacnikova, S.

1998-01-01

The Cyclotron Laboratory (CYLAB) should fill the gap in the field of nuclear medicine, radiotherapy, basic research, metrology of ionizing radiation, education and implications of accelerator technology existing today in Slovak Republic. The main planned activities of this facility are in the fields of nuclear medicine (production of radioisotopes for Positron Emission Tomography - PET and for oncology) and radiotherapy (neutron capture therapy, fast neutron therapy and proton therapy). The radiobiological and biophysical research will be closely connected with medical applications, particularly with radiotherapy. Problems to be addressed include the determination of the values of Relative Biological Effectiveness (RBE) for different types of ionizing radiation involved in the therapy, microdosimetric measurements and calculations, which are indispensable in the calculation of the absorbed dose (lineal and specific energy spectra) at the cellular and macromolecular level. Radiation biophysics and medical physics help in creating therapeutic plans for radiotherapy (NCT and fast neutron therapy). In nuclear medicine, in diagnostic and therapeutical procedures it is necessary to assess the biodistribution of radiopharmaceuticals and to calculate doses in target and critical organs and to determine whole body burden - effective equivalent dose for newly developed radiopharmaceuticals

Philosophy of veterinary radiobiology twenty years after the Chernobyl disaster

International Nuclear Information System (INIS)

Dvorak, P.; Toropila, M.

2006-01-01

The basic objective is to provide safe foodstuffs. This approach has connection with the food chain protection including the diagnostics and the acute radiation disease therapy at the farm animals. The extra significance is given to the research of technologies which can reduce the activity of the contaminated foodstuffs. In the field of the ionizing radiation effect research in live organisms attention should be devoted to the new alternative bio-tests. The low-dose effect or the interaction with other negative physical and chemical aspects of the environment is mainly considered. In cooperation with human medicine, it is necessary to develop radiotherapy and to study the effects of therapy and radiotherapy. From the standpoint of perspective technologies, it is advisable to focus on irradiation of the foodstuffs in veterinary radiobiology. (authors)

SU-E-T-399: Determination of the Radiobiological Parameters That Describe the Dose-Response Relations of Xerostomia and Disgeusia From Head and Neck Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Mavroidis, P; Stathakis, S; Papanikolaou, N [University of Texas Health Science Center, UTHSCSA, San Antonio, TX (United States); Peixoto Xavier, C [University of Coimbra, Coimbra, Coimbra (Portugal); Costa Ferreira, B [University of Aveiro, Coimbra, Coimbra (Portugal); Khouri, L; Carmo Lopes, M do [IPOCFG, EPE, Coimbra, Coimbra (Portugal)

2014-06-01

Purpose: To estimate the radiobiological parameters that describe the doseresponse relations of xerostomia and disgeusia from head and neck cancer radiotherapy. To identify the organs that are best correlated with the manifestation of those clinical endpoints. Finally, to evaluate the goodnessof- fit by comparing the model predictions against the actual clinical results. Methods: In this study, 349 head and neck cancer patients were included. For each patient the dose volume histograms (DVH) of parotids (separate and combined), mandible, submandibular glands (separate and combined) and salivary glands were calculated. The follow-up of those patients was recorded at different times after the completion of the treatment (7 weeks, 3, 7, 12, 18 and 24 months). Acute and late xerostomia and acute disgeusia were the clinical endpoints examined. A maximum likelihood fitting was performed to calculate the best estimates of the parameters used by the relative seriality model. The statistical methods of the error distribution, the receiver operating characteristic (ROC) curve, the Pearson's test and the Akaike's information criterion were utilized to assess the goodness-of-fit and the agreement between the pattern of the radiobiological predictions with that of the clinical records. Results: The estimated values of the radiobiological parameters of salivary glands are D50 = 25.2 Gy, γ = 0.52, s = 0.001. The statistical analysis confirmed the clinical validity of those parameters (area under the ROC curve = 0.65 and AIC = 38.3). Conclusion: The analysis proved that the treatment outcome pattern of the patient material can be reproduced by the relative seriality model and the estimated radiobiological parameters. Salivary glands were found to have strong volume dependence (low relative seriality). Diminishing the biologically effective uniform dose to salivary glands below 30 Gy may significantly reduce the risk of complications to the patients irradiated for

SU-E-T-399: Determination of the Radiobiological Parameters That Describe the Dose-Response Relations of Xerostomia and Disgeusia From Head and Neck Radiotherapy

International Nuclear Information System (INIS)

Mavroidis, P; Stathakis, S; Papanikolaou, N; Peixoto Xavier, C; Costa Ferreira, B; Khouri, L; Carmo Lopes, M do

2014-01-01

Purpose: To estimate the radiobiological parameters that describe the doseresponse relations of xerostomia and disgeusia from head and neck cancer radiotherapy. To identify the organs that are best correlated with the manifestation of those clinical endpoints. Finally, to evaluate the goodnessof- fit by comparing the model predictions against the actual clinical results. Methods: In this study, 349 head and neck cancer patients were included. For each patient the dose volume histograms (DVH) of parotids (separate and combined), mandible, submandibular glands (separate and combined) and salivary glands were calculated. The follow-up of those patients was recorded at different times after the completion of the treatment (7 weeks, 3, 7, 12, 18 and 24 months). Acute and late xerostomia and acute disgeusia were the clinical endpoints examined. A maximum likelihood fitting was performed to calculate the best estimates of the parameters used by the relative seriality model. The statistical methods of the error distribution, the receiver operating characteristic (ROC) curve, the Pearson's test and the Akaike's information criterion were utilized to assess the goodness-of-fit and the agreement between the pattern of the radiobiological predictions with that of the clinical records. Results: The estimated values of the radiobiological parameters of salivary glands are D50 = 25.2 Gy, γ = 0.52, s = 0.001. The statistical analysis confirmed the clinical validity of those parameters (area under the ROC curve = 0.65 and AIC = 38.3). Conclusion: The analysis proved that the treatment outcome pattern of the patient material can be reproduced by the relative seriality model and the estimated radiobiological parameters. Salivary glands were found to have strong volume dependence (low relative seriality). Diminishing the biologically effective uniform dose to salivary glands below 30 Gy may significantly reduce the risk of complications to the patients irradiated for

Study of quality effects on radiobiological actions, 1

International Nuclear Information System (INIS)

Iwanami, Shigeru; Nakazawa, Keiji; Matsubayashi, Takashi; Hashimoto, Shozo.

1979-01-01

In order to interpret the quality effects of high LET radiation on the radiobiological actions, the target theory formulated by Oda on basis of the microdose concept introduced by Rossi has been developed to express intertrack effect (cumulative effect) and intratrack effect (non-cumulative effect) separately. Analysis for the dose-survival relation by this theory have been discussed with comparison of those of Rossi or Bender. If the target for the intertrack effect was the same one for the intratrack effect, it was found in this theory that the contribution of the intertrack effect for the cell lethality was larger than that of the intratrack effect in the case of high LET radiation as well as in that of low LET ones. The survival rates of Escherichia coli B/r and B sub(s-1) irradiated with heavy ions such as He, C, N and O at 4 MeV/a.m.u. and neutrons at 1, 2 and 5 MeV were calculated with this theory. The results were in reasonable agreement with experimental ones. (author)

Particularities of the human genome immunological effects under radiogenic stress conditions

International Nuclear Information System (INIS)

Coretchi, L.

2010-01-01

In this paper the immunological effects and individual dosimeter control results of the occupationally exposed workers (OEW) employed in the radiological therapy and radiological diagnostic are presented. The peripheral blood lymphocytes immunological phenotypization has been made by using monoclonal antibodies ('Sorbent' LTD, Moscow, Russia). The number of CD3+, CD4+, CD8+, CD16+, CD19+ T-lymphocytes and CDHLA DR has been determined by utilizing 'FACS-COUNT' flow cytometry and 'LOMO' luminescent microscope. Length of service (seniority) in the radiogenic stress conditions, age and individual accumulated doses of the OEW were taken into consideration during the results' analysis. The thermoluminescent dosimeters have been used in the process of individual dosimeter monitoring of the OEW. A data base was created in Access and afterwards exported to Microsoft Excel, the latter being used for descriptive statistic. The results demonstrated the general dysfunction of the OEW immunological system, which manifested itself through the diminution, balance or co-expression of the superficial determinants responsible with immunity system. The individual doses of the investigated OEW were within admissible levels according to Fundamental Norms of Radiation Protection standards. (authors)

High value of the radiobiological parameter Dq correlates to expression of the transforming growth factor beta type II receptor in a panel of small cell lung cancer cell lines

DEFF Research Database (Denmark)

Hougaard, S; Krarup, M; Nørgaard, P

1998-01-01

Our panel of SCLC cell lines have previously been examined for their radiobiological characteristics and sensitivity to treatment with TGF beta 1. In this study we examined the possible correlations between radiobiological parameters and the expression of the TGF beta type II receptor (TGF beta......-rII). We have, in other studies, shown that the presence of TGF beta-rII was mandatory for transmitting the growth inhibitory effect of TGF beta. The results showed a statistically significant difference in Dq, i.e. the shoulder width of the survival curve, between cell lines expressing TGF beta......-rII and cell lines which did not express the receptor (P = 0.01). Cell lines expressing TGF beta-rII had a high Dq-value. TGF beta-rII expression did not correlate with any other radiobiological parameters. We suggest that an intact growth inhibitory pathway mediated by the TGF beta-rII may have a significant...

Environmental Research Division annual report: Center for Human Radiobiology, July 1982-June 1983

International Nuclear Information System (INIS)

1984-03-01

This is the fourteenth Annual Report of the Center for Human Radiobiology. New cases of bone cancer and carcinoma of head sinuses are occurring at a rate of about one per year in patients who acquired radium burdens 50 to 60 years ago. Several papers deal with dosimetry of alpha-emitting radionuclides in man, in animals, or in the environment. The report concludes with an appendix containing data on the exposure of 2312 persons whose radium content has been determined and an appendix listing the classical radium-related malignancies (osteosarcomas and carcinomas of the paranasal sinuses and mastoid)

On the cells of origin of radiogenic thyroid cancer

International Nuclear Information System (INIS)

Clifton, K.H.; Domann, F.E.; Groch, K.M.

1991-01-01

A major effort has been devoted to studies of the origins of radiogenic and hormonally-induced cancer at the cellular level in vivo. The studies has provided evidence that the functional thyroid follicules (follicular units, FU) which are formed in grafts of monodispersed rat thyroid cells, and hence the thyroid tumors which later develop in such grafts, are clonal in origin. Transplantation assays indicate that the clonogens comprise 1% of the cells in monodispersed suspensions of normal thyroid tissue. Carcinogenesis studies show that neoplastic initiation of thyroid clonogens by radiation is a commo event. Promotion-progression to cancer from radiation initiated clonogens has, however, been shown to be inversely related to the total grafted thyroid cell number. It is thus important to further define the physiology and population kinetics of the thyroid clonogens under different hormonal conditions both in situ and following transplantion. This report briefly summarizes recent data on (a) local cell-cell and remote hormonal feedback interactions during neoplastic promotion of initiated cells among the progeny of grafted clonogens in multicellular FU; (b) clonogenic cell population kinetics in situ during goitrogenesis and goiter involution; and (c) the reestablishment of the thyroid-hypothalamus-pituitary hormonal feedback system in thyroid cell-grafted thyroidectomized rats and its dependence on the formation of FU by the grafted clonogens. These results support the conclusion that the thyroid gland contains a small sub-population of clonogenic epithelial cells which posess many stem cell-like characteristics. (N.K.)

Research in radiobiology: Annual report of work in progress in the internal irradiation program

International Nuclear Information System (INIS)

Miller, S.C.; Buster, D.S.

1987-01-01

In the early 1950's the Atomic Energy Commission established at the University of Utah a large, long-term study designed to investigate the toxicity of internally deposited radionuclides in beagles. The first animals were injected on December 1, 1952 and thus began an odyssey unusual in modern science both for its duration and continued scientific interest and relevance. The original dogs were injected with 239 Pu and 226 Ra. Later, studies were initiated with 241 Am, 249 Cf, 252 Cf, 253 Es, 224 Ra, 228 Ra, 90 Sr, and 228 Th. These studies were unique and have and will continue to contribute valuable scientific information on the behavior and effects of these substances in biological systems. We feel that the data collected from these studies will be useful for many decades to come as we ask more demanding questions relative to radionuclides and environmental, biological and health issues. While this publication will be the last of our series Research in Radiobiology, the lifespan carcinogenesis studies are continuing under a collaborative arrangement with the I.T.R.I. Beginning in 1988, the colony status tables of dogs in the Utah studies and reports of research by the Radiobiology faculty will be included in the annual I.T.R.I. report. Under our new collaborative arrangements with the I.T.R.I. for the conduct of the lifespan carcinogenesis studies, we expect a continued high level of scientific productivity from our faculty

Magnetic Hyperthermia and Radiation Therapy: Radiobiological Principles and Current Practice †

Directory of Open Access Journals (Sweden)

Spiridon V. Spirou

2018-06-01

Full Text Available Hyperthermia, though by itself generally non-curative for cancer, can significantly increase the efficacy of radiation therapy, as demonstrated by in vitro, in vivo, and clinical results. Its limited use in the clinic is mainly due to various practical implementation difficulties, the most important being how to adequately heat the tumor, especially deep-seated ones. In this work, we first review the effects of hyperthermia on tissue, the limitations of radiation therapy and the radiobiological rationale for combining the two treatment modalities. Subsequently, we review the theory and evidence for magnetic hyperthermia that is based on magnetic nanoparticles, its advantages compared with other methods of hyperthermia, and how it can be used to overcome the problems associated with traditional techniques of hyperthermia.

Construction of cell model of silenced Ku80 and the radiobiology change of HeLa cell

International Nuclear Information System (INIS)

Zhuang Liang; Yu Shiying; Huang Xiaoyuan; Xiong Huihua; Xiong Hua; Li Xiaolan; Leng Yan

2007-01-01

Objective: To construct the cell model of Ku80 with expression inhibited by siRNA and to explore the role of Ku80 in radiobiology. Methods: Ku80-siRNA expression plasmids were constructed and HeLa cells were transfected with these plasmids by lipofectamine. Western blotting was used to measure the expression of Ku80. After irradiation with 6 MV X ray, cells were collected and analyzed by flow cytometry for apoptosis and cell cycle at 24, 48 and 72 h; The radiobiology parameters of four cell lines were acquired by clone formation array. Results: Three stable transfected cell clones were obtained, and the inhibition rates of Ku80 protein expression of two positive clones were 89.3% and 96.4%; The apoptosis rates of HeLa cells Ku80 inhibited were higher than control cells at 48 and 72 after X ray irradiation (P 0.05). HeLa cells of silenced Ku80 had lower SF 2 and D 0 than control cells, and their SER (sensitization enhancement ratio) based on D 10 were 1.315 and 1.365, respectively. Conclusions: The HeLa cell models with Ku80 expression suppressed were successfully established; the inhibition of Ku80 by siRNA could enhance the radiosensitivity of HeLa cells. (authors)

Light ions radiobiological effects on human tumoral cells: measurements modelling and application to hadron-therapy

International Nuclear Information System (INIS)

Jalade, P.

2005-11-01

In classical radiotherapy, the characteristics of photons interactions undergo limits for the treatment of radioresistant and not well located tumours. Pioneering treatments of patients at the Lawrence Laboratory at Berkeley has demonstrated two advantages of hadrons beams: the Relative Biologic Effect (the RBE) and the ballistic of the beams. Since 1994, the clinical centre at Chiba, has demonstrated successfully the applicability of the method. A physics group, managed by G. Kraft, at Darmstadt in Germany, has underlined the advantages of carbon beams. An European pool, called ENGIGHT (European Network for LIGHt ion Therapy) has been created in which the French ETOILE project appeared. The purpose of the thesis concerns measurements and models of 'in vitro' human cells survival. In the first part, the nowadays situation in particles interactions, tracks and cells structures and radiobiology is presented here. The second is devoted to the models based on the beam tracks and localization of the physical dose. Discussion of sensitivity to various parameters of the model has been realized with the help of numerical simulations. Finally the predictions of the improved model has been compared to experimental irradiations of human cells with argon and carbon beams of the GANIL machine. Conclusion of such study shows the performance and limits of a local model for predicting the radiobiological efficiency of light ions in hadron-therapy. (author)

Competing risk model for reduction in life expectancy from radiogenic latent cancer

International Nuclear Information System (INIS)

Davis, H.T.

1978-01-01

Because of the large number of persons who could potentially receive low doses of radiation as a result of a nuclear reactor accident, the number of fatalities from latent cancers is generally larger than the early, or prompt, fatalities. For this reason the latent cancer fatality risk of reactor accidents is perceived as being more important than the early fatality risk. In addition, there exists the temptation to add the latent cancer fatality risk to the early fatality risk for the purpose of comparing reactor accident risks to other risks that society is exposed to, such as automobile accidents, airplane accidents, hurricanes, etc. However, the impact on the individual, and society as a whole, due to latent cancer fatalities is significantly different from the impact produced by early fatalities. Early fatalities generally result in appreciable life shortening for the affected individual while latent cancer fatalities generally result in very limited life shortening. A mathematical model was developed to express the reduction in life expectancy due to latent radiogenic cancer as a function of dose received

Limitations of a convolution method for modeling geometric uncertainties in radiation therapy: the radiobiological dose-per-fraction effect

International Nuclear Information System (INIS)

Song, William; Battista, Jerry; Van Dyk, Jake

2004-01-01

The convolution method can be used to model the effect of random geometric uncertainties into planned dose distributions used in radiation treatment planning. This is effectively done by linearly adding infinitesimally small doses, each with a particular geometric offset, over an assumed infinite number of fractions. However, this process inherently ignores the radiobiological dose-per-fraction effect since only the summed physical dose distribution is generated. The resultant potential error on predicted radiobiological outcome [quantified in this work with tumor control probability (TCP), equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and generalized equivalent uniform dose (gEUD)] has yet to be thoroughly quantified. In this work, the results of a Monte Carlo simulation of geometric displacements are compared to those of the convolution method for random geometric uncertainties of 0, 1, 2, 3, 4, and 5 mm (standard deviation). The α/β CTV ratios of 0.8, 1.5, 3, 5, and 10 Gy are used to represent the range of radiation responses for different tumors, whereas a single α/β OAR ratio of 3 Gy is used to represent all the organs at risk (OAR). The analysis is performed on a four-field prostate treatment plan of 18 MV x rays. The fraction numbers are varied from 1-50, with isoeffective adjustments of the corresponding dose-per-fractions to maintain a constant tumor control, using the linear-quadratic cell survival model. The average differences in TCP and EUD of the target, and in NTCP and gEUD of the OAR calculated from the convolution and Monte Carlo methods reduced asymptotically as the total fraction number increased, with the differences reaching negligible levels beyond the treatment fraction number of ≥20. The convolution method generally overestimates the radiobiological indices, as compared to the Monte Carlo method, for the target volume, and underestimates those for the OAR. These effects are interconnected and attributed

Thermal histories of convective earth models and constraints on radiogenic heat production in the earth

International Nuclear Information System (INIS)

Davies, G.F.

1980-01-01

Thermal histories have been calculated for simple models of the earth which assume that heat is transported by convection throughout the interior. The application of independent constraints to these solutions limits the acceptable range of the ratio of present radiogenic heat production in the earth to the present surface heat flux. The models use an empirical relation between the rate of convective heat transport and the temperature difference across a convecting fluid. This is combined with an approximate proportionality between effective mantle viscosity and T/sup -n/, where T is temperature and it is argued that n is about 30 throughout the mantle. The large value of n causes T to be strongly buffered against changes in the earth's energy budget and shortens by an order of magnitude the response time of surface heat flux to changes in energy budget as compared to less temperature-dependent heat transport mechanisms. Nevertheless, response times with n=30 are still as long as 1 or 2 b.y. Assuming that the present heat flux is entirely primordial (i.e., nonradiogenic) in a convective model leads back to unrealistically high temperatures about 1.7 b.y. ago. Inclusion of exponentially decaying (i.e., radiogenic) heat sources moves the high temperatures further into the past and leads to a transition from 'hot' to 'cool' calculated thermal histories for the case when the present rate of heat production is near 50% of the present rate of heat loss. Requiring the calculated histories to satisfy minimal geological constraints limits the present heat production/heat loss ratio to between about 0.3 and 0.85. Plausible stronger constraints narrow this range to between 0.45 and 0.65. These results are compatible with estimated radiogentic heat production rates in some meteorites and terrestrial rocks, with a whole-earth K/U ratio of 1--2 x 10 4 giving optimal agreement

Radiobiologic comparison of helical tomotherapy, intensity modulated radiotherapy, and conformal radiotherapy in treating lung cancer accounting for secondary malignancy risks

Energy Technology Data Exchange (ETDEWEB)

Komisopoulos, Georgios [Department of Medical Physics, Medical School, University of Patras, Patras (Greece); Mavroidis, Panayiotis, E-mail: mavroidis@uthscsa.edu [Department of Radiation Oncology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, Stockholm (Sweden); Rodriguez, Salvador; Stathakis, Sotirios; Papanikolaou, Nikos [Department of Radiation Oncology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Nikiforidis, Georgios C.; Sakellaropoulos, Georgios C. [Department of Medical Physics, Medical School, University of Patras, Patras (Greece)

2014-01-01

The aim of the present study is to examine the importance of using measures to predict the risk of inducing secondary malignancies in association with the clinical effectiveness of treatment plans in terms of tumor control and normal tissue complication probabilities. This is achieved by using radiobiologic parameters and measures, which may provide a closer association between clinical outcome and treatment delivery. Overall, 4 patients having been treated for lung cancer were examined. For each of them, 3 treatment plans were developed based on the helical tomotherapy (HT), multileaf collimator-based intensity modulated radiation therapy (IMRT), and 3-dimensional conformal radiation therapy (CRT) modalities. The different plans were evaluated using the complication-free tumor control probability (p{sub +}), the overall probability of injury (p{sub I}), the overall probability of control/benefit (p{sub B}), and the biologically effective uniform dose (D{sup ¯¯}). These radiobiologic measures were used to develop dose-response curves (p-D{sup ¯¯} diagram), which can help to evaluate different treatment plans when used in conjunction with standard dosimetric criteria. The risks for secondary malignancies in the heart and the contralateral lung were calculated for the 3 radiation modalities based on the corresponding dose-volume histograms (DVHs) of each patient. Regarding the overall evaluation of the different radiation modalities based on the p{sub +} index, the average values of the HT, IMRT, and CRT are 67.3%, 61.2%, and 68.2%, respectively. The corresponding average values of p{sub B} are 75.6%, 70.5%, and 71.0%, respectively, whereas the average values of p{sub I} are 8.3%, 9.3%, and 2.8%, respectively. Among the organs at risk (OARs), lungs show the highest probabilities for complications, which are 7.1%, 8.0%, and 1.3% for the HT, IMRT, and CRT modalities, respectively. Similarly, the biologically effective prescription doses (D{sub B}{sup ¯¯}) for the

Radiobiological responses for two cell lines following continuous low dose-rate (CLDR) and pulsed dose rate (PDR) brachytherapy

International Nuclear Information System (INIS)

Hanisch, Per Henrik; Furre, Torbjoern; Olsen, Dag Rune; Pettersen, Erik O.

2007-01-01

The iso-effective irradiation of continuous low-dose-rate (CLDR) irradiation was compared with that of various schedules of pulsed dose rate (PDR) irradiation for cells of two established human lines, T-47D and NHIK 3025. Complete single-dose response curves were obtained for determination of parameters α and β by fitting of the linear quadratic formula. Sublethal damage repair constants μ and T 1/2 were determined by split-dose recovery experiments. On basis of the acquired parameters of each cell type the relative effectiveness of the two regimens of irradiation (CLDR and PDR) was calculated by use of Fowler's radiobiological model for iso-effect irradiation for repeated fractions of dose delivered at medium dose rates. For both cell types the predicted and observed relative effectiveness was compared at low and high iso-effect levels. The results indicate that the effect of PDR irradiation predicted by Fowler's model is equal to that of CLDR irradiation for both small and large doses with T-47D cells. With NHIK 3025 cells PDR irradiation induces a larger effect than predicted by the model for small doses, while it induces the predicted effect for high doses. The underlying cause of this difference is unclear, but cell-cycle parameters, like G2-accumulation is tested and found to be the same for the two cell lines

Radiogenic 3He/4He Estimates and Their Effect on Calculating Plio-Pleistocene Cosmogenic 3He Ages of Alluvial-Fan Terraces in the Lower Colorado River Basin, USA

Science.gov (United States)

Fenton, C.; Pelletier, J.

2005-12-01

Several alluvial-fan terraces near Topock, AZ were created by successive entrenchment of Pliocene and Pleistocene alluvial-fan gravels shed from the adjacent Black Mountains along the lower Colorado River corridor below Hoover Dam. These fans interfinger with and overlie main-stem Colorado River sands and gravels and grade to terrace levels that correspond with pre-existing elevations of the Colorado River. Absolute dates for the ages of Quaternary deposits on the lower Colorado River are rare and cosmogenic 3He age estimates of these surfaces would help constrain the timing of aggradation and incision in the lower Colorado River corridor. We analyzed individual basalt boulders from several terrace surfaces for total 3He/4He concentrations to calculate cosmogenic 3He ages of each fan terrace; 3He/4He values, expressed as R/Ra where Ra is the 3He/4He of air, range from 0.29 to 590. Black Mountain volcanic rocks have reported K-Ar ages between 15 and 30 Ma and basalt samples from adjacent alluvial fans contain 0.42 to 47× 1012 at/g of 4He, which has likely accumulated due to nuclear processes. The amount of radiogenic 3He/4He can be significant in old rocks with young exposure ages and can complicate determination of cosmogenic 3 He content. Alpha-decay of U, Th, and their daughter isotopes produces large amounts of 4He, whereas significant amounts of radiogenic 3He are only produced through the neutron bombardment of Li and subsequent beta-decay of tritium. We measured Li, U, Th, major and rare-earth element concentrations in whole-rock basalts and mineral separates. These concentrations are used to estimate the ratio of radiogenic helium contributed to the total helium system in our samples. Li concentrations typically range from 6 to 17 ppm, with one outlier of 62 ppm. U contents range from calculations predict that the average radiogenic helium (R/Ra) contributed to the total helium in Black Mountain basalt samples is 0.011. Other noble gas studies have shown

Radiobiology of systemic radiation therapy.

Science.gov (United States)

Murray, David; McEwan, Alexander J

2007-02-01

Although systemic radionuclide therapy (SRT) is effective as a palliative therapy in patients with metastatic cancer, there has been limited success in expanding patterns of utilization and in bringing novel systemic radiotherapeutic agents to routine clinical use. Although there are many factors that contribute to this situation, we hypothesize that a better understanding of the radiobiology and mechanism of action of SRT will facilitate the development of future compounds and the future designs of prospective clinical trials. If these trials can be rationalized to the biological basis of the therapy, it is likely that the long-term outcome would be enhanced therapeutic efficacy. In this review, we provide perspectives of the current state of low-dose-rate (LDR) radiation research and offer linkages where appropriate with current clinical knowledge. These include the recently described phenomena of low-dose hyper-radiosensitivity-increased radioresistance (LDH-IRR), adaptive responses, and biological bystander effects. Each of these areas require a major reconsideration of existing models for radiation action and an understanding of how this knowledge will integrate into the evolution of clinical SRT practice. Validation of a role in vivo for both LDH-IRR and biological bystander effects in SRT would greatly impact the way we would assess therapeutic response to SRT, the design of clinical trials of novel SRT radiopharmaceuticals, and risk estimates for both therapeutic and diagnostic radiopharmaceuticals. We believe that the current state of research in LDR effects offers a major opportunity to the nuclear medicine community to address the basic science of clinical SRT practice, to use this new knowledge to expand the use and roles of SRT, and to facilitate the introduction of new therapeutic radiopharmaceuticals.

Radiation damage and repair in cells and cell components. Part 2. Physical radiations and biological significance. Final report

International Nuclear Information System (INIS)

Fluke, D.J.

1984-08-01

The report comprises a teaching text, encompassing all physical radiations likely to be of biological interest, and the relevant biological effects and their significance. Topics include human radiobiology, delayed effects, radiation absorption in organisms, aqueous radiation chemistry, cell radiobiology, mutagenesis, and photobiology

Hypo-fractionated treatment in radiotherapy: radio-biological models Tcp and NTCP

International Nuclear Information System (INIS)

Astudillo V, A. J.; Mitsoura, E.; Paredes G, L.; Resendiz G, G.

2014-08-01

At the present time the breast cancer in Mexico has the first place of incidence of the malignant neoplasia s in the women, and represents 11.34% of all the cancer cases. On the other hand, the treatments for cancer by means of ionizing radiations have been dominated under the approaches of the medical radio-oncologists which have been based on test and error by many years. The radio-biological models, as the Tcp, NTCP and dosimetric variables, for their clinical application in the conventional radiotherapy with hypo-fractionation have as purpose predicting personalized treatment plans that they present most probability of tumor control and minor probability of late reactions, becoming this way support tools in the decisions taking for the patient treatments planning of Medical Physicists and Radio-oncologists. (Author)

Research in radiobiology

Energy Technology Data Exchange (ETDEWEB)

NONE

1959-10-15

Safety in the production and use of radioactive substances and protection against ionizing radiation are matters of direct concern to the International Atomic Energy Agency. On the one hand, the Agency has been trying to establish standards of safe practice, and on the other, it has been trying to promote research on the biological effects of radiation. Radiobiological research is of basic importance in the context of the growing use of radiation sources all over the world, because measures of radiation protection or the treatment of radiation sickness can be adequate and effective only when there is a clear and thorough understanding of the effects of ionizing radiation on living organisms. IAEA has placed several contracts with scientific institutions in different countries for research on problems that may throw some light on various aspects of this problem. One line of research is to study the effects of small doses of radiation, a study that is essential in establishing the maximum permissible doses for radiation workers and others. A contract has been given to the Pharmacological Institute of Vienna University for the investigation of the response of cells, particularly of the nervous system, to low-level exposures. Another important field of research is the protective action of certain substances against the effects of radiation. Under a research contract given by IAEA, the mode of protective action of certain chemical compounds is being studied at the Physiological Institute of Vienna University. Of the possible effects of radiation, those of a genetic nature have caused widespread concern. Under an IAEA contract, cytogenetical investigations are being carried out at the Institute of Medical Genetics of Uppsala University on the effects of radiation on human cells grown in vitro. While certain conclusions about the effects of radiation on human cells can be deduced from test tube experiments, some valuable inferences can also be drawn from studies of the

Speciation of rhenium and radiogenic osmium in molybdenite by sensitive XAFS

International Nuclear Information System (INIS)

Takahashi, Y.

2006-01-01

For the speciation of trace elements in rocks and minerals, fluorescence XAFS using energy-dispersive Ge detector has been often used. By this method, however, high quality fluorescence XAFS cannot be obtained under intense scattering and/or fluorescence from other predominant elements in the samples. To deal with this problem, we developed a system for fluorescence XAFS using a bent crystal analyzer to selectively extract fluorescence x-rays of a target element. In this paper, speciation of Os in molybdenite has been studied as an example of the application. Radiometric dating using various radioactive decay systems has been widely applied to various terrestrial and extraterrestrial materials. Although the information is closely related to chemical stabilities of parent and daughter nuclides and the reliability of the radiometric dating, there have been few investigations on the direct identification of the chemical state of the daughter nuclides. In this study, we chose Re-Os system in molybdenite for the possible application of this idea, since initial abundance of Os in molybdenite is often negligible compared with radiogenic Os in molybdenite rich in Re. From XAFS spectra, we have investigated local structure of Re and Os in molybdenite. Details of the analyses will be given in the presentation. (author)

Oxygen as a product of water radiolysis in high-LET tracks. II. Radiobiological implications

International Nuclear Information System (INIS)

Baverstock, K.F.; Burns, W.G.

1981-01-01

Consideration is given to the possibility that molecular oxygen generated in the tracks of energetic heavy ions is responsible for the reduction in oxygen enhancement ratio (OER) with increasing linear energy transfer (LET) observed for the loss of reproductive capacity caused by radiation in many cellular organisms. Yields of oxygen relationship of OER to LET for two organisms, Chlamydomonas reinhardii and Shigella flexneri, using a simple diffusion kinetic model for radiobiological action which takes account of the diffusion of oxygen after its formation. The results of these calculations show that the model accounts well for the shape of the OER vs. LET relationship

Research in radiobiology. Annual report of work in progress in the Internal Irradiation Program

International Nuclear Information System (INIS)

Miller, S.C.

1980-01-01

Survival data on 160 nonirradiated control beagles of the University of Utah's Radiobiology Laboratory were analyzed. The animals died during a period from 1958 into 1979. The average age at death of animals which died during the 1958 to 1965 interval was significantly less than that of those whose deaths occurred in the 1965 to 1979 interval. The best estimate for average age at death for Super-Selected nonirradiated control beagles of the colony is 4864 +- 901 days. The Super-Selected dogs excluded those dying because of epilepsy, lymphosarcoma, lymphoma or accidents, and also excluded all dogs dying before 1966

Determination of damage and In vivo DNA repairing through the unicellular in gel electrophoresis technique; Determinacion del dano y la reparacion del ADN In vivo mediante la tecnica de electroforesis unicelular en gel

Energy Technology Data Exchange (ETDEWEB)

Mendiola C, M.T.; Morales R, P. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1997-07-01

The experimental conditions were standardized for the unicellular in gel electrophoresis technique setting up (EUG) at the Cellular Radiobiology laboratory. Preliminary experiments were realized with human cells and mouse which were exposed to ionizing radiation or hydroxide peroxide (H{sub 2}O{sub 2}) to induce DNA damage and to verify the technique performance. It was analysed the In vivo repairing kinetics of induced damage by gamma radiation in mouse leukocytes which were exposed to {sup 137} Cs source and taking samples of peripheric blood of the tail of each mouse at different exposure times and processing them for EUG. In function of the cells proportion with damage in each time it was determined the existence of fast repairing mechanism at the first 15 minutes followed by a slight increase in the damage and a late repairing stage between 30 and 90 minutes. It was analysed this behavior and the potentiality of this In vivo system. (Author)

Basic principles of molecular effects of irradiation.

Science.gov (United States)

Selzer, Edgar; Hebar, Alexandra

2012-02-01

In order to understand the consequences of radiation a thorough understanding of the radiobiological mechanisms of the molecular up to the clinical level is of importance. Radiobiology therefore combines the basic principles of physics as well as biology and medicine and is concerned with the action of radiation from the subcellular level up to the living organism. Topics of interest and relevance are covered in much more broadness as is possible in the short following article in the literature to which the interested reader is referred to. Classical books in this field were written by Steel et al. (1989) as well as by Hall (1994). Topics usually covered by radiobiological reviews are the classification of different types of radiation, cell cycle dependency of radiation effects, types of radiation damage and cell death, dose response curves, measurement of radiation damage, the oxygen effect, relative biological effectiveness, the influence of dose rate, and several other important research areas. This short overview will concentrate on a subset of radiobiological topics of high importance and relative novelty.

Experimental radiotherapy and clinical radiobiology. Vol. 18. Proceedings; Experimentelle Strahlentherapie und Klinische Strahlenbiologie. Bd. 18. Proceedings

Energy Technology Data Exchange (ETDEWEB)

Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemann, H Peter; Zips, Daniel [eds.

2009-07-15

The proceedings on experimental radiotherapy and clinical radiobiology contain two review articles (prediction of normal tissue reactions after radiotherapy, ?H2AX foci as a marker for DNA double-strand breaks) and 34 contributions to the following topics: Hypoxia and molecular mechanisms of radiation resistance; biological imaging of the tumor micromilieu; DNA repair, genomic instability and carcerogenesis; molecular factors of radiation resistance; actual controversial discussion on possible irradiation caused metastasis risk enhancement; EGFR inhibition and irradiation; biology of experimental radiation/ normal tissue toxicity.

Radioactivity and radiogenic heat production in the oil field of the Reconcavo Basin; Radioatividade e geracao de calor radiogenico em pocos petroliferos na Bacia do Reconcavo

Energy Technology Data Exchange (ETDEWEB)

Alves Junior, Paulo B.; Argollo, Roberto M. de [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Centro de Pesquisa em Geofisica e Geologia

2004-07-01

The production of radiogenic heat in the terrestrial crust is due mainly to U, Th and K presents in the rocks. In this work, we use the gamma-ray spectrometry technique to determine the contents of these elements in drill cuttings and obtaining profiles of heat production rates in oils wells of the Reconcavo basin. In the total, we measure 640 samples of drill cuttings from wells FFL-1 and MGP-34 ceded by PETROBRAS. The thorium contents vary from 1.6 to 25.5 ppm, the uranium contents varied from 0.5 to 5.82 ppm, the potassium samples varied from 0.05 to 2.25 % and the production rates of radiogenic heat varied among 0.50 to 10.85 10{sup -4} {mu}W kg{sup -1}. With the profiles heat production rates obtained, a correlation was verified among these rates and the lithologies at wells FFL-1 and MGP-34. These values will be used in the correlation between these samples at wells and the sample collected at blooming. (author)

Radiation biology of medical imaging

CERN Document Server

Kelsey, Charles A; Sandoval, Daniel J; Chambers, Gregory D; Adolphi, Natalie L; Paffett, Kimberly S

2014-01-01

This book provides a thorough yet concise introduction to quantitative radiobiology and radiation physics, particularly the practical and medical application. Beginning with a discussion of the basic science of radiobiology, the book explains the fast processes that initiate damage in irradiated tissue and the kinetic patterns in which such damage is expressed at the cellular level. The final section is presented in a highly practical handbook style and offers application-based discussions in radiation oncology, fractionated radiotherapy, and protracted radiation among others. The text is also supplemented by a Web site.

Laser-driven particle acceleration for radiobiology and radiotherapy: where we are and where we are going

Science.gov (United States)

Giulietti, Antonio

2017-05-01

Radiation therapy of tumors progresses continuously and so do devices, sharing a global market of about $ 4 billions, growing at an annual rate exceeding 5%. Most of the progress involves tumor targeting, multi-beam irradiation, reduction of damage on healthy tissues and critical organs, dose fractioning. This fast-evolving scenario is the moving benchmark for the progress of the laser-based accelerators towards clinical uses. As for electrons, both energy and dose requested by radiotherapy are available with plasma accelerators driven by lasers in the power range of tens of TW but several issues have still to be faced before getting a prototype device for clinical tests. They include capability of varying electron energy, stability of the process, reliability for medical users. On the other side hadron therapy, presently applied to a small fraction of cases but within an exponential growth, is a primary option for the future. With such a strong motivation, research on laser-based proton/ion acceleration has been supported in the last decade in order to get performances suitable to clinical standards. None of these performances has been achieved so far with laser techniques. In the meantime a rich crop of data have been obtained in radiobiological experiments performed with beams of particles produced with laser techniques. It is quite significant however that most of the experiments have been performed moving bio samples to laser labs, rather moving laser equipment to bio labs or clinical contexts. This give us the measure that laser community cannot so far provide practical devices usable by non-laser people.

Radiobiological characteristics of cervical cancer

International Nuclear Information System (INIS)

Kagabu, Teruo; Kobayashi, Takashi; Nanayama, Kunihiko

1976-01-01

In order to observe the radiobiological characteristics of cervical cancer, the author carried out irradiation of 60 Co in 16 cases of cervical cancer. The primary lesion of each case was exposed to radiation of 100 R once a day, 40 times in sequence, totaling 4,000 R. To evaluate this results, the vaginal smears were obtained everyday and examined for changes in cancerous cells caused by the irradiation. The results of our study showed that cervical cancer could be classified into three groups according to the radiosensitivity of its cancerous cells. In the group of low-radiosensitivity (11 cases of 16), the cancerous cells decreased gradually, and enlargement of the nuclei of the cancerous cells was observed from 2,000 R of irradiation, but the majority of the cancerous cells were those of nucleus after the irradiation of 4,000 R. In all of the 5 uterus removed, residual cancer lesion was noted. The radiocuability was unfavourable. In the group of high-radiosensitivity (4 cases of 16), the cancerous cells decreased remarkablly. Enlargement of nucleus was noted from 1,000 R of the irradiation, the cancerous cells of small-sized nucleus appeared with the irradiation of 3,000 R but the cancerous cells almost disappeared with the irradiation of 4,000 R. The radiocuability was favourable. In the group of combination of high-radiosensitivity and low-radiosensitivity portions (one case of 16), the cancerous cells decreased remarkablly until the exposure to the radiation of 2,000 R but thereafter did slowly. In a removed uterus, the cancer lesion was noted, but the prognosis was favourable. The foregoing results suggest that changes in the nuclear diameter of the cancerous cells in vaginal smears during irradiation can tell the radiosensitivity of the cancerous cells. (Kanao, N.)

Radiobiology of Cell Renewal Systems

Energy Technology Data Exchange (ETDEWEB)

Patt, H. M. [Laboratory of Radiobiology, University of California Medical Center, San Francisco, CA (United States)

1968-08-15

In recent years, considerable attention has been given to quantitative aspects of radiation effects on cell renewal systems. The behaviour of stem-type cells has been a focal point of interest, and it has been assumed by many that the fraction of surviving stem cells is the principal determinant of the probability of survival of the irradiated system or organism. The apparent close similarity in dose requirements for impairment of reproductive capacity, and the similarity in early repair and in stage sensitivity in vitro and in vivo.clearly indicate that purely cellular phenomena are reflected in the organized population. It does not necessarily follow, however, that there is a straightforward relationship between radiation effects on stem cells and the response of systems or organisms. Indeed, this is not so. It is abundantly clear that differential radiosensitivity is anchored in a number of variables that are associated with the organizational framework of the system and its environment. Many, but not all, effects can be understood in terms of the normal kinetics of the developmental pathway. Yet, deviations from normal kinetics that are minor in the steady state can have profound significance in the perturbed state. To understand the radiobiology of cell renewal systems and to place the many possible variables in reasonable perspective, we need to know a good deal more about the interplay of the component parts than we do at present. When we view the totality of an organized cell population, it seems necessary to postulate mechanisms external to any given cell in the regulation of the balanced sequence of proliferation and differentiation. At present, we have only a vague idea about this. Most attention has been directed to the proliferative process and it is encouraging to note the growing interest in the more developmental facets of cell renewal. (author)

Growth of the continental crust: constraints from radiogenic isotope geochemistry

International Nuclear Information System (INIS)

Taylor, P.N.

1988-01-01

Most models for evolution of continental crust are expressed in the form of a diagram illustrating the cumulative crustal mass (normalized relative to the present crustal mass) as a function of time. Thus, geochronological data inevitably play a major role in either constructing or testing crustal growth models. For all models, determining the start-time for effective crustal accretion is of vital importance. To this end, the continuing search for, and reliable characterization of, the most ancient crustal rock-units remains a worthy enterprise. Another important role for geochronology and radiogenic isotope geochemistry is to assess the status of major geological events as period either of new crust generation or of reworking of earlier formed continental crust. For age characterization of major geological provinces, using the critieria outined, the mass (or volume) of crust surviving to the present day should be determinable as a function of crust formation age. More recent developments, however, appear to set severe limitations on recycling of crust, at least by the process of sediment subduction. In modeling crustal growth without recycling, valuable constaints on growth rate variations through time can be provided if variations in the average age of the continental crust can be monitored through geological history. The question of the average age of the exposed continental crust was addressed by determining Sm-Nd crustal residence model ages (T-CR) for fine-grained sediment loads of many of the world's major rivers

Radiobiological arguments for and clinical possibilities of unconventional fractionating rhythms

International Nuclear Information System (INIS)

Herrmann, T.; Voigtmann, L.

1986-01-01

Radiobiological considerations are presented using unconventional fractionating rhythms. The aim of this method is to enlarge the therapeutic dimensions between maximum tumor destruction and most careful treatment of late responding cell systems. These late responding tissues show a very similar dose-time reaction, probably by reason of a causal injury on cells of the capillary endothelium. In linear-quadratic models for the estimation of the parameters of the number of fractions and total treatment period it becomes evident that a careful treatment of late responding tissue can be attained by reduction of the single dose per fraction. Because with partition of a total dose in several fractions at daily irradiation a longer repopulation period is available also for the tumor irradiations are presented, done repeatedly during the day. Accelerated fractionation (same fractionating number in reduced treatment period) are contrasted to hyperfractionation (increased fractionating number within the same total treatment period) and possibilities in application are suggested. (author)

Estimation of the radiobiological and kinetic factors of radiosensitivity and radiocurability of metastases of squamous cell carcinoma of the larynx to neck lymph nodes

International Nuclear Information System (INIS)

Maciejewski, B.

1985-01-01

The usefulness of theoretical model of tumour growth and experimental methods of kinetic and radiobiological factors for analysis of clinical data to improve the effectiveness of dose fractionation are checked. 176 refs., 27 figs., 19 tabs. (author)

Comparison of volumetric modulated arc therapy and intensity modulated radiation therapy for whole brain hippocampal sparing treatment plans based on radiobiological modeling

Directory of Open Access Journals (Sweden)

Ethan Kendall

2018-01-01

Full Text Available Introduction: In this article, we report the results of our investigation on comparison of radiobiological aspects of treatment plans with linear accelerator-based intensity-modulated radiation therapy and volumetric-modulated arc therapy for patients having hippocampal avoidance whole-brain radiation therapy. Materials and Methods: In this retrospective study using the dose-volume histogram, we calculated and compared biophysical indices of equivalent uniform dose, tumor control probability, and normal tissue complication probability (NTCP for 15 whole-brain radiotherapy patients. Results and Discussions: Dose-response models for tumors and critical structures were separated into two groups: mechanistic and empirical. Mechanistic models formulate mathematically with describable relationships while empirical models fit data through empirical observations to appropriately determine parameters giving results agreeable to those given by mechanistic models. Conclusions: Techniques applied in this manuscript could be applied to any other organs or types of cancer to evaluate treatment plans based on radiobiological modeling.

Radiobiological effects in organisms of plants and animals exposed to ionizing irradiation in the Chernobyl NPP zone

International Nuclear Information System (INIS)

Panchenko, N.A.; Arkhipov, N.P.; Alesina, M.Y.; Kuchma, V.I.; Gaschak, S.P.; Burov, N.I.

1997-01-01

Influence of ionizing radiation on forest ecosystems most clearly revealed itself near the Chernobyl NPP (ChNPP), were magnitudes of absorbed doses reached 'lethal' values, as applied to conifers. Main contribution to absorbed dose was due to beta-radiation of short-living radionuclides. To largest extent the radiobiological effects appeared at injured plantations of pines and firs. Nevertheless, during the first year maximum absorbed doses influenced also on leaf-bearing trees (birch, alder, asp) which then rehabilitated themselves completely

Survey of post-gamma-ray colony-forming ability, DNA metabolism and oncogene status in non-malignant fibroblast strains from cancer-prone families and individual cancer patients

International Nuclear Information System (INIS)

Paterson, M.C.; Aubin, R.A.; Fourney, R.M.; Mirzayans, R.

1989-01-01

The in vitro radiobiological studies described here have focused on highly selected individuals comprising some of the most likely cases of predisposition to radiogenic cancer ascertained to date. Our results argue against the existence, within the general population, of quantitatively significant subgroups sensitive to the carcinogenic effects of ubiquitous low-level radiation. In fact, of the forty-six cancer-susceptible conditions examined, only four (i.e. members of the cancer-prone lineage in two kindreds and two isolated patients), exhibited abnormal cellular response to γ-rays in vitro. These findings indicate that in this unprecedented collection of high cancer risk conditions, the incidence of abnormal radiation cytotoxicity is only about two-fold above that found in a randomly selected group of age-matched healthy subjects (i.e, about 9% [4/46 conditions] versus about 5% [1/21 volunteers]). This interpretation of the data assumes, however, that the post-γ-ray CFA assay performed on cultured dermal fibroblasts is a reliable and sensitive indicator of the donor's susceptibility to develop radiogenic cancer, irrespective of the anatomical site or histological type of the tumour(s). (author)

‘Survival’: a simulation toolkit introducing a modular approach for radiobiological evaluations in ion beam therapy

Science.gov (United States)

Manganaro, L.; Russo, G.; Bourhaleb, F.; Fausti, F.; Giordanengo, S.; Monaco, V.; Sacchi, R.; Vignati, A.; Cirio, R.; Attili, A.

2018-04-01

One major rationale for the application of heavy ion beams in tumour therapy is their increased relative biological effectiveness (RBE). The complex dependencies of the RBE on dose, biological endpoint, position in the field etc require the use of biophysical models in treatment planning and clinical analysis. This study aims to introduce a new software, named ‘Survival’, to facilitate the radiobiological computations needed in ion therapy. The simulation toolkit was written in C++ and it was developed with a modular architecture in order to easily incorporate different radiobiological models. The following models were successfully implemented: the local effect model (LEM, version I, II and III) and variants of the microdosimetric-kinetic model (MKM). Different numerical evaluation approaches were also implemented: Monte Carlo (MC) numerical methods and a set of faster analytical approximations. Among the possible applications, the toolkit was used to reproduce the RBE versus LET for different ions (proton, He, C, O, Ne) and different cell lines (CHO, HSG). Intercomparison between different models (LEM and MKM) and computational approaches (MC and fast approximations) were performed. The developed software could represent an important tool for the evaluation of the biological effectiveness of charged particles in ion beam therapy, in particular when coupled with treatment simulations. Its modular architecture facilitates benchmarking and inter-comparison between different models and evaluation approaches. The code is open source (GPL2 license) and available at https://github.com/batuff/Survival.

Literature study of the radiobiological parameters of Caesium-137 required for evaluating internal irradiation doses as a function of age

International Nuclear Information System (INIS)

Garnier, A.

1968-01-01

This document reassembles information published in scientific literature on radiobiological parameters of Cs-137, necessary for the estimate of the internal irradiation dose of man according to his age (during growth). The data are completed by a commented review of the mathematical models, proposed in order to value the irradiation doses from ingested cesium and the biological parameters. (author) [fr

Potential application of radiogenic isotopes and geophysical methods to understand the hydrothermal dystem of the Upper Geyser Basin, Yellowstone National Park

Science.gov (United States)

Paces, James B.; Long, Andrew J.; Koth, Karl R.

2015-01-01

Numerous geochemical and geophysical studies have been conducted at Yellowstone National Park to better understand the hydrogeologic processes supporting the thermal features of the Park. This report provides the first 87Sr/86Sr and 234U/238U data for thermal water from the Upper Geyser Basin (UGB) intended to evaluate whether heavy radiogenic isotopes might provide insight to sources of groundwater supply and how they interact over time and space. In addition, this report summarizes previous geophysical studies made at Yellowstone National Park and provides suggestions for applying non-invasive ground and airborne studies to better understand groundwater flow in the subsurface of the UGB. Multiple samples from Old Faithful, Aurum, Grand, Oblong, and Daisy geysers characterized previously for major-ion concentrations and isotopes of water (δ2H, δ18O, and 3H) were analyzed for Sr and U isotopes. Concentrations of dissolved Sr and U are low (4.3–128 ng g-1 Sr and 0.026–0.0008 ng g-1 U); consequently only 87Sr/86Sr data are reported for most samples. Values of 87Sr/86Sr for most geysers remained uniform between April and September 2007, but show large increases in all five geysers between late October 2007 and early April, 2008. By late summer of 2008, 87Sr/86Sr values returned to values similar to those observed a year earlier. Similar patterns are not present in major-ion data measured on the same samples. Furthermore, large geochemical differences documented between geysers are not observed in 87Sr/86Sr data, although smaller differences between sites may be present. Sr-isotope data are consistent with a stratified hydrologic system where water erupted in spring and summer of 2007 and summer of 2008 equilibrated with local intracaldera rhyolite flows at shallower depths. Water erupted between October 2007 and April 2008 includes greater amounts of groundwater that circulated deep enough to acquire a radiogenic 87Sr/86Sr, most likely from Archean basement

Radiobiological considerations in gynaecological HDR and LDR brachytherapy

International Nuclear Information System (INIS)

Bauer, M.; Schulz-Wendtland, R.

1989-01-01

In brachytherapy the advantages of high dose rate over low dose rate afterloading therapy were obvious. Out-patient treatment becomes possible, the position of the sources is reproducible and can be observed during the treatment and the patients have to be immobilised for only a short time, giving less psychological stress and a decreased risk of thrombosis and embolism. When changing from LDR to HDR afterloading therapy we are not yet able to evaluate its biological impact. Radiobiological considerations and our experimental data, however, give us the following clinical consequences by using HDR brachytherapy: There is a need for about 15 fractions or more and each increase in dose rate requires higher fractioning. Due to the steep dose rate decline and the inhomogeneous dose distribution, multiple equivalence factors are necessary when fractioning is not sufficiently high. Correction factors to reduce the dose close to the source are low, with increasing distance from the source they increase. If HDR radiation therapy is used, the percutaneous dose in the pelvic wall region should be reduced. The reduction of the dose in HDR brachytherapy is a compromise to limit the side effects caused by the radiation. The drawback is a small therapeutic range and reduced therapeutic effectivity at the tumour. (orig.) [de

DNA damage and repair in oncogenic transformation by heavy ion radiation

Science.gov (United States)

Yang, T. C.; Mei, M.; George, K. A.; Craise, L. M.

1996-01-01

Energetic heavy ions are present in galactic cosmic rays and solar particle events. One of the most important late effects in risk assessment is carcinogenesis. We have studied the carcinogenic effects of heavy ions at the cellular and molecular levels and have obtained quantitative data on dose-response curves and on the repair of oncogenic lesions for heavy particles with various charges and energies. Studies with repair inhibitors and restriction endonucleases indicated that for oncogenic transformation DNA is the primary target. Results from heavy ion experiments showed that the cross section increased with LET and reached a maximum value of about 0.02 micrometer2 at about 500 keV/micrometer. This limited size of cross section suggests that only a fraction of cellular genomic DNA is important in radiogenic transformation. Free radical scavengers, such as DMSO, do not give any effect on induction of oncogenic transformation by 600 MeV/u iron particles, suggesting most oncogenic damage induced by high-LET heavy ions is through direct action. Repair studies with stationary phase cells showed that the amount of reparable oncogenic lesions decreased with an increase of LET and that heavy ions with LET greater than 200 keV/micrometer produced only irreparable oncogenic damage. An enhancement effect for oncogenic transformation was observed in cells irradiated by low-dose-rate argon ions (400 MeV/u; 120 keV/micrometer). Chromosomal aberrations, such as translocation and deletion, but not sister chromatid exchange, are essential for heavy-ion-induced oncogenic transformation. The basic mechanism(s) of misrepair of DNA damage, which form oncogenic lesions, is unknown.

A study of the radiobiological modeling of the conformal radiation therapy in cancer treatment

Science.gov (United States)

Pyakuryal, Anil Prasad

Cancer is one of the leading causes of mortalities in the world. The precise diagnosis of the disease helps the patients to select the appropriate modality of the treatments such as surgery, chemotherapy and radiation therapy. The physics of X-radiation and the advanced imaging technologies such as positron emission tomography (PET) and computed tomography (CT) plays an important role in the efficient diagnosis and therapeutic treatments in cancer. However, the accuracy of the measurements of the metabolic target volumes (MTVs) in the PET/CT dual-imaging modality is always limited. Similarly the external beam radiation therapy (XRT) such as 3D conformal radiotherapy (3DCRT) and intensity modulated radiation therapy (IMRT) is the most common modality in the radiotherapy treatment. These treatments are simulated and evaluated using the XRT plans and the standard methodologies in the commercial planning system. However, the normal organs are always susceptible to the radiation toxicity in these treatments due to lack of knowledge of the appropriate radiobiological models to estimate the clinical outcomes. We explored several methodologies to estimate MTVs by reviewing various techniques of the target volume delineation using the static phantoms in the PET scans. The review suggests that the more precise and practical method of delineating PET MTV should be an intermediate volume between the volume coverage for the standardized uptake value (SUV; 2.5) of glucose and the 50% (40%) threshold of the maximum SUV for the smaller (larger) volume delineations in the radiotherapy applications. Similarly various types of optimal XRT plans were designed using the CT and PET/CT scans for the treatment of various types of cancer patients. The qualities of these plans were assessed using the universal plan-indices. The dose-volume criteria were also examined in the targets and organs by analyzing the conventional dose-volume histograms (DVHs). The biological models such as tumor

2. International conference. Radiobiological consequences of nuclear accidents; Russian-Norwegian Satellite Symposium on nuclear accidents, radioecology and health. Abstracts. Part 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

Materials on radiobiological effect of ionizing radiation under emergency situations are presented. The radiation contamination of environmental media after the Chernobyl NPP accident (ground, earth and water ecological systems), effect of external and internal irradiation on the inhabitants of the region are estimated. Time characteristic of radiation risk of originating tumors and genetic injuries is given.

2. International conference. Radiobiological consequences of nuclear accidents; Russian-Norwegian Satellite Symposium on nuclear accidents, radioecology and health. Abstracts. Part 2

International Nuclear Information System (INIS)

1994-01-01

Materials on radiobiological effect of ionizing radiation under emergency situations are presented. The radiation contamination of environmental media after the Chernobyl NPP accident (ground, earth and water ecological systems), effect of external and internal irradiation on the inhabitants of the region are estimated. Time characteristic of radiation risk of originating tumors and genetic injuries is given

Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone

Science.gov (United States)

Lowenstern, Jacob B.; Evans, William C.; Bergfeld, D.; Hunt, Andrew G.

2014-01-01

Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone hotspot2. However, much of the helium emitted from this region is actually radiogenic helium-4 produced within the crust by α-decay of uranium and thorium. Here we show, by combining gas emission rates with chemistry and isotopic analyses, that crustal helium-4 emission rates from Yellowstone exceed (by orders of magnitude) any conceivable rate of generation within the crust. It seems that helium has accumulated for (at least) many hundreds of millions of years in Archaean (more than 2.5 billion years old) cratonic rocks beneath Yellowstone, only to be liberated over the past two million years by intense crustal metamorphism induced by the Yellowstone hotspot. Our results demonstrate the extremes in variability of crustal helium efflux on geologic timescales and imply crustal-scale open-system behaviour of helium in tectonically and magmatically active regions.

Lithospheric stresses due to radiogenic heating of an ice-silicate planetary body - Implications for Ganymede's tectonic evolution

Science.gov (United States)

Zuber, M. T.; Parmentier, E. M.

1984-01-01

Thermal evolution models of differentiated and undifferentiated ice-silicate bodies containing long-lived radiogenic heat sources are examined. Lithospheric sresses arise due to volume change of the interior and temperature change in the lithosphere. For an undifferentiated body, the surface stress peaks early in the evolution, while in the differentiated case, stresses peak later and continue to accumulate for longer periods of time. The variation of near-surface stress with depth shows that stresses for the undifferentiated body initially penetrate to great depths, but rapidly concentrate within a few kilometers of the surface. For the differentiated body, elastic stresses never accumulate at a depth greater than a few kilometers. These models are applied to consider long-term rdioactive heating as a possible mechanism of tectonic activity and bright terrain formation on Ganymede.

Stochastic, weighted hit size theory of cellular radiobiological action

International Nuclear Information System (INIS)

Bond, V.P.; Varma, M.N.

1982-01-01

A stochastic theory that appears to account well for the observed responses of cell populations exposed in radiation fields of different qualities and for different durations of exposure is described. The theory appears to explain well most cellular radiobiological phenomena observed in at least autonomous cell systems, argues for the use of fluence rate (phi) instead of absorbed dose for quantification of the amount of radiation involved in low level radiation exposure. With or without invoking the cell sensitivity function, the conceptual improvement would be substantial. The approach suggested also shows that the absorbed dose-cell response functions currently employed do not reflect the spectrum of cell sensitivities to increasing cell doses of a single agent, nor can RBE represent the potency ratio for different agents that can produce similar quantal responses. Thus, for accurate comparison of cell sensitivities among different cells in the same individual, or between the cells in different kinds of individuals, it is necessary to quantify cell sensitivity in terms of the hit size weighting or cell sensitivity function introduced here. Similarly, this function should be employed to evaluate the relative potency of radiation and other radiomimetic chemical or physical agents

Amchitka Radiobiological Program progress report, January 1979-December 1979

International Nuclear Information System (INIS)

Thornberg, L.D.; Sibley, T.H.; Nakatani, R.E.

1980-07-01

The objective of the Amchitka Radiobiological Program for the period 1970-1979 was to determine the extent of radionuclide contamination from world-wide atmospheric fallout and from the detonation of three underground nuclear blasts on Amchitka Island. The objective is achieved, by the collection and radiological analyses of biological and environmental samples and by background radiation measurements. Leakage of radionuclides from the underground sites of the Amchitka nuclear detonations would be suspected if the contamination was significntly greater than would be expected from world fallout. An account of the program from July 1970 to December 1978 has been given in nine previous reports from the Laboratory of Radiation Ecology to the Nevada Operations Office of the US Department of Energy. This report is an account of the program for calendar year 1979. The results of analyses of the samples collected in 1979 lead to the same conclusions as in previous years; i.e., there is no evidence that the radionuclide contamination at Amchitka Island is greater than would be expected from world fallout except for a slight contamination of the Long Shot Mud Pits with tritium

Calcium biogeochemical cycle at the beech tree-soil solution interface from the Strengbach CZO (NE France): insights from stable Ca and radiogenic Sr isotopes

Science.gov (United States)

Schmitt, Anne-Désirée; Gangloff, Sophie; Labolle, François; Chabaux, François; Stille, Peter

2017-09-01

Calcium (Ca) is the fourth most abundant element in mineral nutrition and plays key physiological and structural roles in plant metabolism. At the soil-water-plant scale, stable Ca isotopes are a powerful tool for the identification of plant-mineral interactions and recycling via vegetation. Radiogenic Sr isotopes are often used as tracers of Ca sources and mixtures of different reservoirs. In this study, stable Ca and radiogenic Sr are combined and analysed in several organs from two beech trees that were collected in June and September in the Strengbach critical zone observatory (CZO) (NE France) and in corresponding soil solutions. At the beech-tree scale, this study confirms the field Ca adsorption (i.e., physico-chemical mechanism and not vital effects) on carboxyl acid groups of pectin in the apoplasm of small roots. The analysis of the xylem sap and corresponding organs shows that although the Strengbach CZO is nutrient-poor, Ca seems to be non-limiting for tree-growth. Different viscosities of xylem sap between the stemwood and branches or leaves can explain δ44/40Ca values in different tree-organs. The bark and phloem 40Ca-enrichments could be due to Ca-oxalate precipitation in the bark tissues and in the phloem. The results from this study regarding the combination of these two isotopic systems show that the isotopic signatures of the roots are dominated by Ca fractionation mechanisms and Sr, and thus Ca, source variations. In contrast, translocation mechanisms are only governed by Ca fractionation processes. This study showed that at the root-soil solution interface, litter degradation was not the main source of Ca and Sr and that the soil solutions are not the complement of uptake by roots for samples from the 2011/2013 period. The opposite is observed for older samples. These observations indicate the decreasing contribution of low radiogenic Sr fluxes, such as recycling, alimenting the soil solutions. Such reduced importance of nutrient uptake and

Hidden stressors in the clonogenic assay used in radiobiology experiments

International Nuclear Information System (INIS)

Potter, M.D.E.; Suchowerska, N.; Rizvi, S.; McKenzie, D.R.

2011-01-01

Full text: While clonogenic assays are extensively used in radiobiology, there is no widely accepted procedure for choosing the composition of the cell culture media. Cell line suppliers recommend a specific culture medium for each cell line, however a researcher will frequently customize this aspect of the protocol by supplementing the recommended support medium with additives. For example, many researchers add antibiotics, in order to avoid contamination of cells and the consequent loss of data, with little discussion of the influence of the antibiotics on the clonogenic survival of the cells. It is assumed that the effect of any variables in the growth medium on cell survival is taken into consideration by comparing the survival fraction relative to that of controls grown under the same conditions. In the search for better cancer treatment, the effect of various stressors on clonogenic cell survival is under investigation. This study seeks to identify and test potential stressors commonly introduced into the cell culture medium, which may confound the response to radiation. (author)

Effect of SL25 on radiogenic xerostomia in the radiotherapy of tumors in the region of neck and face

International Nuclear Information System (INIS)

Hassenstein, E.; Mueller, R.; Reinhard, H.J.; Kali-Chemie A.G., Hannover; Tieraerztliche Hochschule Hannover

1978-01-01

The radiogenic xerostomia often poses problems to the radiotherapeutist because this symptom can become so severe that treatment has to be interrupted or in some cases even stopped. The therapeutic success can become uncertain because of such deviations from the irradiation scheme. Because of promising observations reported in literature, we have examined the stimulating effect on the salivation produced by the test preparation SL25 from Kali-Chemie Pharma GmbH in Hannover. A double blindfold test was made. Only three out of fourteen patients (22%) in the active substance group declared to feel a relief of the xerostomia, whereas in the control group five out of twenty patients (25%) felt this relief. (orig.) [de

Early Tissue Effects of Stereotactic Body Radiation Therapy for Spinal Metastases

NARCIS (Netherlands)

Steverink, Jasper G.; Willems, Stefan M.; Philippens, Marielle E.P.; Kasperts, Nicolien; Eppinga, Wietse S.C.; Versteeg, Anne L.; van der Velden, Joanne M.; Faruqi, Salman; Sahgal, Arjun; Verlaan, Jorrit Jan

2018-01-01

Purpose: Stereotactic body radiation therapy (SBRT) is a highly effective and potentially ablative treatment for complex spinal metastases. Recent data have suggested radiobiologic effects of SBRT that expand beyond the traditional concept of DNA damage. Antitumor immunity, vascular damage leading

Problems of radiation medicine and radiobiology

International Nuclear Information System (INIS)

Bazyka, D.A.

2014-01-01

Research activities and scientific advance achieved in 2013 at the State Institution 'National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine' (NRCRM) concerning medical problems of the Chornobyl disaster, radiation medicine, radiobiology, radiation hygiene and epidemiology in collaboration with the WHO network of medical preparedness and assistance in radiation accidents are outlined in the annual report. Key points include the research results of XRCC1 and XPD gene polymorphism in thyroid cancer patients, CD38 gene GG genotype as a risk factor for chronic lymphocytic leukemia, frequency of 185delAG and 5382insC mutations in BRCA1 gene in women with breast cancer, cognitive function and TERF1, TERF2, TERT gene expression both with telomere length in human under the low dose radiation exposure. The 'source-scattering/shielding structures-man' models for calculation of partial dose values to the eye lens and new methods for radiation risk assessment were developed and adapted. Radiation risks of leukemia including chronic lymphocytic leukemia in the cohort of liquidators were published according to the 'case-control' study results after 20 years of survey. Increase of non-tumor morbidity in liquidators during the 1988-2011 with the maximum level 12-21 years upon irradiation was found. Incidence in evacuees appeared being of two-peak pattern i.e. in the first years after the accident and 12 years later. Experimental studies have concerned the impact of radio-modifiers on cellular systems, reproductive function in the population, features of the child nutrition in radiation contamination area were studied. Report also shows the results of scientific and organizational, medical and preventive work, staff training, and implementation of innovations. The NRCRM Annual Report was approved at the Scientific Council meeting of NAMS on March 3, 201

Micro-and nanodosimetry for radiobiological planning in radiotherapy and cancer risk assessment in radiation environment

International Nuclear Information System (INIS)

Rosenfeld, A.B.

2006-01-01

Full text: Microdosimetry and nanodosimetry can provide unique information for prediction of radiobiological properties of radiation, which is important in radiation therapy for accurate dose planning and in radiation protection for cancer induction risk assessment. This demand measurements of the pattern of energies deposited by ionizing radiation on cellular scale and DNA levels.Silicon microelectronics technology is offering a unique opportunity for replacing gas proportional counters (TEPC) with miniature detectors for regional microdosimetry. Silicon on Insulator (SOI) technology has been used for the development of arrays of micron size sensitive volumes for modelling energy deposited in biological cells. The challenge in silicon microdosimetry is the development of well defined sensitive volume (SV) and full charge collection deposited by ionizing radiation in the SV. First generation SOI microdosimeters were developed at CMRP and investigated in a wide range of radiation fields for proton and neutron therapies and recently on isotopic neutron sources and heavy ions with energy up to lGeV/jj,m which are typical for deep space radiation environment. Microdosimetric spectra were obtained in a phantom that are well matched to TEPC and Monte Carlo simulations. Evidence that radiations with the same LET exhibit different biological effects demand development of new sensors sensitive to the track structure of ions or the type of particle for prediction of radiobiological effect of radiation using radiobiological models. New monolithic Si AE-E telescope of cellular size for simultaneous regional microdosimetry and particle identification will be presented and results will be discussed. The new design of the SOI microdosimeter is based on 3D micron and submicron size of Si SVs. This approach allows improvement in the accuracy of the Si microdosimetry because of full charge collection and the ability to measure low LET as low as 0.01 keV/jjm, which is similar to TEPC

Development of a tool computer to compensate for interruptions of treatment and radiobiological comparisons Tr in external radiotherapy; Desarrollo de una herramienta informatica para la compensacion de interrupciones de tratamiento y comparaciones radiobiologicas en radioterapia externa

Energy Technology Data Exchange (ETDEWEB)

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

2013-07-01

Outages unscheduled in the course of external beam radiation treatments, and the loss of probability of tumour control (TCP), which make it necessary to have a tool that allows the adjustment of the compensation of the absorbed dose required to keep the biological effect on the tumor, controlling the possible impact on the organ at risk. In order to perform this radiobiological quickly setting has been developed a software application that also allows comparison of treatments with different subdivisions from the point of view of radiobiological. (Author)

Amchitka Radiobiological Program. Final report, July 1970-December 1979

International Nuclear Information System (INIS)

Sibley, T.H.; Tornberg, L.D.

1982-11-01

The Amchitka Radiobiological Program, to collect biological and environmental samples for radiological analyses, began in 1970 and continued through 1979. The principal objective was to determine the extent of radionuclide contamination from worldwide atmospheric fallout and from the detonation of three underground nuclear tests on Amchitka. Leakage of radionuclides from the underground test sites would be suspected if the amount of contamination was significantly greater than could be attributed to worldwide fallout or if an unexpected assemblage of radionuclides was detected. No radionuclides from the underground sites were detected, except for tritium from the Long Shot test (1965) which produced increased tritium concentrations in surface water and freshwater plants near the test site. This final report compiles all previous data into one report and considers the temporal trends in these data. Two naturally occurring radionuclides, 40 K and 7 Be, were the most abundantly occurring radionuclides in most samples; in lichen samples either 137 Cs or 144 Ce had the highest activity. All samples were below applicable Radiation Protection Guides and by 1979 most samples were near or below the statistical detection limits. Increased concentrations of short-lived fallout radionuclides following the Chinese atmospheric tests were found in freshwater and seawater samples and in most indicator organisms

Dictionary of radiation protection, radiobiology and nuclear medicine. English-German-French-Russian. Strahlenschutz, Strahlenbiologie, Nuklearmedizin. Englisch-Deutsch-Franzoesisch-Russisch

Energy Technology Data Exchange (ETDEWEB)

Sube, R

1985-01-01

This multilingual dictionary covers the subject fields of radiation protection, radiobiology, and nuclear medicine with about 12,000 terms in each language. All terms are supplemented by one or more abbreviations of 22 special branches to assure the use of the very relevant terms. Special branches listed are for instance decontamination, dosimetry, atomic legislation, radiation detectors, radiography (medical), radiotherapy, safeguards, shielding, tansportation and storage. The terminology used in the International Nuclear Information System (INIS) of the IAEA has been completely taken into account.

Targeting the epidermal growth factor receptor in radiotherapy: radiobiological mechanisms, preclinical and clinical results

International Nuclear Information System (INIS)

Baumann, Michael; Krause, Mechthild

2004-01-01

Background and purpose: Inhibition of the epidermal growth factor receptor (EGFR) is a fastly developing field in preclinical and clinical cancer research. This review presents the current status of knowledge and discusses radiobiological mechanisms which may underly the efficacy of EGFR inhibitors combined with irradiation. Materials and methods: Preclinical and clinical results on combined targeting of the EGFR and irradiation from the literature and from this laboratory are reviewed. Focus is given to the radiobiological rationale of this approach and to endpoints of experimental radiotherapy. Results: Overexpression of the EGFR is associated with decreased local tumour control after radiotherapy, especially when the overall treatment time is long. Inhibition of the EGFR either alone or in combination with irradiation decreases the growth rate of tumours expressing this receptor. Preclinical data provide proof-of-principle that local tumour control may be improved by combining irradiation with C225 mAb. In a randomised phase III clinical trial, simultaneous irradiation and treatment with the EGFR antibody Cetuximab (Erbitux[reg]; C225) in head and neck cancer patients resulted in significantly improved locoregional tumour control and survival compared to curative irradiation alone. Acute skin reactions increased in the experimental arm. The underlying mechanisms of enhanced radiation effects of combined EGFR inhibition with irradiation and of the partly conflicting results in different studies are poorly understood. There is increasing evidence, that important intertumoral heterogeneity in the response to EGFR inhibition alone and combined with irradiation exists, which appears to be at least partly dependent on specific mutations of the receptor as well as of molecules that are involved in the intracellular signal transduction pathway. Conclusions and outlook: Further investigations at all levels of the translational research chain exploring the mechanisms of

Proceedings of the international conference on radiation biology and clinical applications: a molecular approach towards innovations in applied radiobiology and a workshop on strategies in radiation research

International Nuclear Information System (INIS)

2013-10-01

Innovations in radiotherapy approaches to cancer and radiation biology research is of growing interest in radiation researchers to conduct preclinical studies at their centers and translating the results as soon as possible to clinical radiotherapy practice. Recent papers have greatly enriched the current knowledge of radiation oncology, especially radiobiology and molecular oncology, and this has radically changed the oncology practice in radiation therapy in just a few years. The conference theme highlights the molecular and cellular responses within tissue and higher levels of mammalian biological organization. New experimental radiobiology research to underpin current and future regulatory decisions setting workplace exposure limits. To develop rapid, high-precision analytical methods that assess radiation exposure doses from clinical samples and thus aid in the triage and medical management of radiological casualties. Innovative approaches to improve the accuracy, dose range, ease of use, and speed of classical biodosimetry. Papers relevant to INIS are indexed separately

Low-Mass Dark Matter Search Results and Radiogenic Backgrounds for the Cryogenic Dark Matter Search

Energy Technology Data Exchange (ETDEWEB)

Pepin, Mark David [Univ. of Minnesota, Minneapolis, MN (United States)

2016-12-01

An ever-increasing amount of evidence suggests that approximately one quarter of the energy in the universe is composed of some non-luminous, and hitherto unknown, “dark matter”. Physicists from numerous sub-fields have been working on and trying to solve the dark matter problem for decades. The common solution is the existence of some new type of elementary particle with particular focus on weakly interacting massive particles (WIMPs). One avenue of dark matter research is to create an extremely sensitive particle detector with the goal of directly observing the interaction of WIMPs with standard matter. The Cryogenic Dark Matter Search (CDMS) project operated at the Soudan Underground Laboratory from 2003–2015, under the CDMS II and SuperCDMS Soudan experiments, with this goal of directly detecting dark matter. The next installation, SuperCDMS SNOLAB, is planned for near-future operation. The reason the dark-matter particle has not yet been observed in traditional particle physics experiments is that it must have very small cross sections, thus making such interactions extremely rare. In order to identify these rare events in the presence of a background of known particles and interactions, direct detection experiments employ various types and amounts of shielding to prevent known backgrounds from reaching the instrumented detector(s). CDMS utilized various gamma and neutron shielding to such an effect that the shielding, and other experimental components, themselves were sources of background. These radiogenic backgrounds must be understood to have confidence in any WIMP-search result. For this dissertation, radiogenic background studies and estimates were performed for various analyses covering CDMS II, SuperCDMS Soudan, and SuperCDMS SNOLAB. Lower-mass dark matter t c2 inent in the past few years. The CDMS detectors can be operated in an alternative, higher-biased, mode v to decrease their energy thresholds and correspondingly increase their sensitivity

Research trends in radiobiology since 40 years. a new approach: the enzymatic repair function of DNA, internal factor in evolution of biological systems under irradiation

International Nuclear Information System (INIS)

Mouton, R.

1968-01-01

In the first part of the report, the author attempts to draw an historical scheme of successive research working hypotheses in radiobiology since 1924. Less than a generation ago the effect of radiation exposure were viewed as being direct, immediate, irreparable and unmodifiable. Now it is generally accepted that radiation lesion can also be indirect, delayed, reparable and often modified with appropriate chemical or biochemical treatment. It was however in 1962-1964 that came the decisive breakthrough in radiobiology with the discovery that the cell possesses a natural active self-defense mechanism against whatever stress would affect the integrity of the genetic message contained in the DNA structure itself. The existence of what could be considered as a fourth DNA function i.e. self-repair by enzymatic action under genetic control-brings at least to radiobiology the missing molecular biology basis it needed to get out of its 'phenomenological night' after abandon of the generalization of Lea's theory through lack of experimental evidence. In the second part, which is a prospective one, the author tries to set an enlarged synthesis considering the possible role of DNA repair system not only in cell survival - in presence or absence of dose modifiers or mutagens - but also in the artificial and natural evolution of biological system exposed to sub-lethal doses of radiation. Most recent data from the literature fit well with what must be still considered as a general working hypothesis. Studies dealing with phenotypic and genotypic characters linked with the acquisition of gamma and UV radiation resistance in 'Escherichia coli K12' has been started by the author, in collaboration with O. Tremeau, in order to bring a new experimental contribution in this respect. (author) [fr

Relationship between radiobiological hypoxia in a C3H mouse mammary carcinoma and osteopontin levels in mouse serum

DEFF Research Database (Denmark)

Lukácová, Slávka; Khalil, Azza Ahmed; Overgaard, Jens

2005-01-01

To investigate the possible relationship between radiobiological hypoxia in a C3H mouse mammary carcinoma and osteopontin (OPN) levels measured in mouse serum. MATERIAL AND METHODS: Experiments were performed in CDF1 mice that were either non-tumour bearing or with different sized tumours implanted...... in the right rear foot. Osteopontin levels in extracted mouse blood serum and tissue from the transplanted tumours were measured using an ELISA assay. The tumour oxygenation status was estimated using the Eppendorf Histograph and the fraction of oxygen partial pressure (pO2) values =5 mm Hg (HF5...

Damage to haemopoiesis, therapeutic strategies and repair mechanisms

International Nuclear Information System (INIS)

Wangenheim, K.H. von; Peterson, H.P.; Feinendegen, L.E.

1993-01-01

Investigations were carried out into the question as to whether stem cells surviving irradiation remain intact, which is suggested by radiobiological experience to date, or have suffered permanent lesions. The development of a test system gauging the quality of stem cells and their progeny on the basis of their proliferation ability led to the conclusion that radiation caused long-term injuries that permanently compromised the entire haemopoietic system. Observations of the regeneration of normal and irradiated bone marrow under homogeneous conditions in animal donors subjected to high-dose radiation as well as determinations of spleen colony size, proliferation factor and number of stem cells pointed to the fact that the vast majority of stem cells were permanently damaged. It could be shown that unspecific genetic lesions remained unchanged in surviving stem cells and were passed on to their progeny. Refinements to the original proliferation test and the in vitro determination of the proliferation ability of stem cells and various blood cell lines permitted to differentiate between several causative factors. Studies on ways to diminish stem cell injuries either by influencing humoral proliferation stimuli during the regenerative phase or by the use of radiation protection substances are already in progress. In addition to the primary studies, tests were performed to examine the effects of low dose irradiation, vitamin E deficiency and a static magnetic field. (orig./MG) [de

Tail's Entropy and dose of critical annihilation: a new view of the problem radiobiological; Entropia de Tsallis y dosis de aniquilacion critica: una nueva vision del problema radiobiologico

Energy Technology Data Exchange (ETDEWEB)

Sotolongo Grau, O.; Rodriguez Perez, D.; Antoranz, J. C.

2011-07-01

The aim of this paper is to present a model based on a minimum radiobiological physical hypotheses containing known models as special cases, allowing to define operations of addition and multiplication dose survival probabilities to fit the experimental data.

Light ion production for a future radiobiological facility at CERN: preliminary studies.

Science.gov (United States)

Stafford-Haworth, Joshua; Bellodi, Giulia; Küchler, Detlef; Lombardi, Alessandra; Röhrich, Jörg; Scrivens, Richard

2014-02-01

Recent medical applications of ions such as carbon and helium have proved extremely effective for the treatment of human patients. However, before now a comprehensive study of the effects of different light ions on organic targets has not been completed. There is a strong desire for a dedicated facility which can produce ions in the range of protons to neon in order to perform this study. This paper will present the proposal and preliminary investigations into the production of light ions, and the development of a radiobiological research facility at CERN. The aims of this project will be presented along with the modifications required to the existing linear accelerator (Linac3), and the foreseen facility, including the requirements for an ion source in terms of some of the specification parameters and the flexibility of operation for different ion types. Preliminary results from beam transport simulations will be presented, in addition to some planned tests required to produce some of the required light ions (lithium, boron) to be conducted in collaboration with the Helmholtz-Zentrum für Materialien und Energie, Berlin.

Transformation of Physical DVHs to Radiobiologically Equivalent Ones in Hypofractionated Radiotherapy Analyzing Dosimetric and Clinical Parameters: A Practical Approach for Routine Clinical Practice in Radiation Oncology

Directory of Open Access Journals (Sweden)

Zoi Thrapsanioti

2013-01-01

Full Text Available Purpose. The purpose of this study was to transform DVHs from physical to radiobiological ones as well as to evaluate their reliability by correlations of dosimetric and clinical parameters for 50 patients with prostate cancer and 50 patients with breast cancer, who were submitted to Hypofractionated Radiotherapy. Methods and Materials. To achieve this transformation, we used both the linear-quadratic model (LQ model and the Niemierko model. The outcome of radiobiological DVHs was correlated with acute toxicity score according to EORTC/RTOG criteria. Results. Concerning the prostate radiotherapy, there was a significant correlation between RTOG acute rectal toxicity and ( and ( dosimetric parameters, calculated for  Gy. Moreover, concerning the breast radiotherapy there was a significant correlation between RTOG skin toxicity and dosimetric parameter, calculated for both  Gy ( and  Gy (. The new tool seems reliable and user-friendly. Conclusions. Our proposed model seems user-friendly. Its reliability in terms of agreement with the presented acute radiation induced toxicity was satisfactory. However, more patients are needed to extract safe conclusions.

European Society for Radiation Biology 21. annual meeting

International Nuclear Information System (INIS)

1988-01-01

The volume contains about 100 abstracts of lectures presented to the conference covering a large variety of topics like: Radiobiology as a base for radiotherapy, radiation carcinogenesis and cellular effects, late and secondary effects of radiotherapy, radioprotection and radiosensitization, heavy ions in radiobiology and space research, microdosimetry and biological dosimetry, radiation effects on the mature and the developing central nervous system, DNA damage and repair and cellular mutations, the imact of radiation on the environment, free radicals in radiation biology

Evaluation of the radiobiological impact of anatomic modifications during radiation therapy for head and neck cancer: Can we simply summate the dose?

International Nuclear Information System (INIS)

Orban de Xivry, Jonathan; Castadot, Pierre; Janssens, Guillaume; Lee, John Aldo; Geets, Xavier; Gregoire, Vincent; Macq, Benoit

2010-01-01

Background and purpose: Adaptive strategies in radiotherapy (RT) require the knowledge of the total dose given to every organ of the body. Because of anatomical changes and setup errors non-rigid registration is necessary to map the different dose fractions to a common reference. This study evaluates practically if the accumulation of all of these registered dose fractions must take radiobiology into account in a classical clinical setting. Materials and methods: Ten patients with head and neck tumors treated by chemo-RT were used. Contrast-enhanced CT scans were acquired prior and during RT following delivery of mean doses of 14.2, 24.5, 35.0 and 44.9 Gy and the planned pre-treatment helical tomotherapy sinograms were applied on the per-treatment CTs to create a series of per-treatment dose distributions corresponding to each per-treatment CT image. In order to calculate the cumulative dose distribution, the per-treatment dose maps were non-rigidly deformed by using the deformation map computed by a non-rigid registration. The deformed dose maps were then summed in two ways: one while taking radiobiology into account and one without. These two strategies were compared using clinical surrogates in the target volumes (TV) and in surrounding organs at risk (OAR). Results: The differences between the strategies, while statistically significant (p < 0.05), are clinically irrelevant. In the OARs, the mean differences stay in the 0.01-0.07 Gy range for the total dose. In the targets, all mean differences stay in the 0.001-0.012 Gy range. However, some local high difference spots appear leading to punctual errors as high as 2.5 Gy. Conclusion: If using current radiotherapy practices and clinical recommendations based on dose surrogates computed globally on OARs and TVs, one does not need to take radiobiological effects into account while accumulating total dose as these lead to very small differences compared to a simple accumulation technique consisting of a linear sum

WE-E-BRE-04: Dual Focal Spot Dose Painting for Precision Preclinical Radiobiological Investigations

Energy Technology Data Exchange (ETDEWEB)

Stewart, J; Lindsay, P [Princess Margaret Cancer Centre, Toronto (Canada); University of Toronto, Toronto (Canada); Jaffray, D [Princess Margaret Cancer Centre, Toronto (Canada); The Techna Institute for the Advancement of Technology for Health, Toronto (Canada)

2014-06-15

Purpose: Recent progress in small animal radiotherapy systems has provided the foundation for delivering the heterogeneous, millimeter scale dose distributions demanded by preclinical radiobiology investigations. Despite advances in preclinical dose planning, delivery of highly heterogeneous dose distributions is constrained by the fixed collimation systems and large x-ray focal spot common in small animal radiotherapy systems. This work proposes a dual focal spot dose optimization and delivery method with a large x-ray focal spot used to deliver homogeneous dose regions and a small focal spot to paint spatially heterogeneous dose regions. Methods: Two-dimensional dose kernels were measured for a 1 mm circular collimator with radiochromic film at 10 mm depth in a solid water phantom for the small and large x-ray focal spots on a recently developed small animal microirradiator. These kernels were used in an optimization framework which segmented a desired dose distribution into low- and high-spatial frequency regions for delivery by the large and small focal spot, respectively. For each region, the method determined an optimal set of stage positions and beam-on times. The method was demonstrated by optimizing a bullseye pattern consisting of 0.75 mm radius circular target and 0.5 and 1.0 mm wide rings alternating between 0 and 2 Gy. Results: Compared to a large focal spot technique, the dual focal spot technique improved the optimized dose distribution: 69.2% of the optimized dose was within 0.5 Gy of the intended dose for the large focal spot, compared to 80.6% for the dual focal spot method. The dual focal spot design required 14.0 minutes of optimization, and will require 178.3 minutes for automated delivery. Conclusion: The dual focal spot optimization and delivery framework is a novel option for delivering conformal and heterogeneous dose distributions at the preclinical level and provides a new experimental option for unique radiobiological investigations

WE-E-BRE-04: Dual Focal Spot Dose Painting for Precision Preclinical Radiobiological Investigations

International Nuclear Information System (INIS)

Stewart, J; Lindsay, P; Jaffray, D

2014-01-01

Purpose: Recent progress in small animal radiotherapy systems has provided the foundation for delivering the heterogeneous, millimeter scale dose distributions demanded by preclinical radiobiology investigations. Despite advances in preclinical dose planning, delivery of highly heterogeneous dose distributions is constrained by the fixed collimation systems and large x-ray focal spot common in small animal radiotherapy systems. This work proposes a dual focal spot dose optimization and delivery method with a large x-ray focal spot used to deliver homogeneous dose regions and a small focal spot to paint spatially heterogeneous dose regions. Methods: Two-dimensional dose kernels were measured for a 1 mm circular collimator with radiochromic film at 10 mm depth in a solid water phantom for the small and large x-ray focal spots on a recently developed small animal microirradiator. These kernels were used in an optimization framework which segmented a desired dose distribution into low- and high-spatial frequency regions for delivery by the large and small focal spot, respectively. For each region, the method determined an optimal set of stage positions and beam-on times. The method was demonstrated by optimizing a bullseye pattern consisting of 0.75 mm radius circular target and 0.5 and 1.0 mm wide rings alternating between 0 and 2 Gy. Results: Compared to a large focal spot technique, the dual focal spot technique improved the optimized dose distribution: 69.2% of the optimized dose was within 0.5 Gy of the intended dose for the large focal spot, compared to 80.6% for the dual focal spot method. The dual focal spot design required 14.0 minutes of optimization, and will require 178.3 minutes for automated delivery. Conclusion: The dual focal spot optimization and delivery framework is a novel option for delivering conformal and heterogeneous dose distributions at the preclinical level and provides a new experimental option for unique radiobiological investigations

Exploring ultrashort high-energy electron-induced damage in human carcinoma cells

International Nuclear Information System (INIS)

Rigaud, O.; Fortunel, N.O.; Vaigot, P.; Cadio, E.; Martin, M.T.; Lundh, O.; Faure, J.; Rechatin, C.; Malka, V.; Gauduel, Y.A.

2010-01-01

In conventional cancer therapy or fundamental radiobiology research, the accumulated knowledge on the complex responses of healthy or diseased cells to ionizing radiation is generally obtained with low-dose rates. Under these radiation conditions, the time spent for energy deposition is very long compared with the dynamics of early molecular and cellular responses. The use of ultrashort pulsed radiation would offer new perspectives for exploring the 'black box' aspects of long irradiation profiles and favouring the selective control of early damage in living targets. Several attempts were previously performed using nanosecond or picosecond pulsed irradiations on various mammalian cells and radiosensitive mutants at high dose rate. The effects of single or multi-pulsed radiations on cell populations were generally analyzed in the framework of dose survival curves or characterized by 2D imaging of γ-H2AX foci and no increase in cytotoxicity was shown compared with a delivery at a conventional dose rate. Moreover, when multi-shot irradiations were performed, the overall time needed to obtain an integrated dose of several Grays again overlapped with the multi-scale dynamics of bio-molecular damage-repair sequences and cell signalling steps. Ideally, a single-shot irradiation delivering a well-defined energy profile, via a very short temporal window, would permit the approach of a real-time investigation of early radiation induced molecular damage within the confined spaces of cell compartments. Owing to the potential applications of intense ultrashort laser for radiation therapy, the model of the A431 carcinoma cell line was chosen. An ultrafast single-shot irradiation strategy was carried out with these radio-resistant human skin carcinoma cells, using the capacity of an innovating laser-plasma accelerator to generate quasi mono-energetic femtosecond electron bunches in the MeV domain and to deliver a very high dose rate of 10 13 Gy s -1 per pulse. The alkaline comet

Radiobiological basis for setting neutron radiation safety standards

International Nuclear Information System (INIS)

Straume, T.

1985-01-01

Present neutron standards, adopted more than 20 yr ago from a weak radiobiological data base, have been in doubt for a number of years and are currently under challenge. Moreover, recent dosimetric re-evaluations indicate that Hiroshima neutron doses may have been much lower than previously thought, suggesting that direct data for neutron-induced cancer in humans may in fact not be available. These recent developments make it urgent to determine the extent to which neutron cancer risk in man can be estimated from data that are available. Two approaches are proposed here that are anchored in particularly robust epidemiological and experimental data and appear most likely to provide reliable estimates of neutron cancer risk in man. The first approach uses gamma-ray dose-response relationships for human carcinogenesis, available from Nagasaki (Hiroshima data are also considered), together with highly characterized neutron and gamma-ray data for human cytogenetics. When tested against relevant experimental data, this approach either adequately predicts or somewhat overestimates neutron tumorigenesis (and mutagenesis) in animals. The second approach also uses the Nagasaki gamma-ray cancer data, but together with neutron RBEs from animal tumorigenesis studies. Both approaches give similar results and provide a basis for setting neutron radiation safety standards. They appear to be an improvement over previous approaches, including those that rely on highly uncertain maximum neutron RBEs and unnecessary extrapolations of gamma-ray data to very low doses. Results suggest that, at the presently accepted neutron dose limit of 0.5 rad/yr, the cancer mortality risk to radiation workers is not very different from accidental mortality risks to workers in various nonradiation occupations

Laser-driven proton beams applied to radiobiological experiments

International Nuclear Information System (INIS)

Yogo, Akifumi

2012-01-01

The proton accelerators based on the high intensity laser system generate shorter and higher pulse beams compared to the conventional particle accelerators used for the cancer therapy. To demonstrate the radiobiological effects of the new proton beams, the program to develop a biological irradiation instrument for the DNA double-strand break was started in the fiscal year 2008. A prototype instrument was made by making use of the J-KAREN (JAEA Kansai Advanced Relativistic Engineering) laser beam. Polyimide thin film targets were used to irradiate A-549 cells. The DNA double-strand break was tested by the fluorescence spectrometry. In the second year the quantitative yield of the DNA double-strand break and its proton dose dependence were measured. The results indicated that they were comparative to the cases of the conventional particle accelerators. In the fiscal year of 2010 the design of the magnetic field for the energy selection has been changed. The new irradiation instrument, the main part of which is only about 40 cm in length as illustrated in the figure, has been constructed and tested. The experiment has been carried out using the human cancer cells (HSG) and the relative biological effectiveness (RBE) has been quantitatively evaluated by the colony assay for varied distribution of the proton beam energy. The survival fractions plotted against the dose were in good agreement with the case of 3 He beam. RBE was found not to be changed up to 1x10 7 Gy/s. Stability of the energy peak, half width and the proton density has been confirmed for this very compact instrument. (S. Funahashi)

On the consistency of Monte Carlo track structure DNA damage simulations

Energy Technology Data Exchange (ETDEWEB)

Pater, Piotr, E-mail: piotr.pater@mail.mcgill.ca; Seuntjens, Jan; El Naqa, Issam [McGill University, Montreal, Quebec H3G 1A4 (Canada); Bernal, Mario A. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, Campinas 13083-859 (Brazil)

2014-12-15

Purpose: Monte Carlo track structures (MCTS) simulations have been recognized as useful tools for radiobiological modeling. However, the authors noticed several issues regarding the consistency of reported data. Therefore, in this work, they analyze the impact of various user defined parameters on simulated direct DNA damage yields. In addition, they draw attention to discrepancies in published literature in DNA strand break (SB) yields and selected methodologies. Methods: The MCTS code Geant4-DNA was used to compare radial dose profiles in a nanometer-scale region of interest (ROI) for photon sources of varying sizes and energies. Then, electron tracks of 0.28 keV–220 keV were superimposed on a geometric DNA model composed of 2.7 × 10{sup 6} nucleosomes, and SBs were simulated according to four definitions based on energy deposits or energy transfers in DNA strand targets compared to a threshold energy E{sub TH}. The SB frequencies and complexities in nucleosomes as a function of incident electron energies were obtained. SBs were classified into higher order clusters such as single and double strand breaks (SSBs and DSBs) based on inter-SB distances and on the number of affected strands. Results: Comparisons of different nonuniform dose distributions lacking charged particle equilibrium may lead to erroneous conclusions regarding the effect of energy on relative biological effectiveness. The energy transfer-based SB definitions give similar SB yields as the one based on energy deposit when E{sub TH} ≈ 10.79 eV, but deviate significantly for higher E{sub TH} values. Between 30 and 40 nucleosomes/Gy show at least one SB in the ROI. The number of nucleosomes that present a complex damage pattern of more than 2 SBs and the degree of complexity of the damage in these nucleosomes diminish as the incident electron energy increases. DNA damage classification into SSB and DSB is highly dependent on the definitions of these higher order structures and their

On the consistency of Monte Carlo track structure DNA damage simulations

International Nuclear Information System (INIS)

Pater, Piotr; Seuntjens, Jan; El Naqa, Issam; Bernal, Mario A.

2014-01-01

Purpose: Monte Carlo track structures (MCTS) simulations have been recognized as useful tools for radiobiological modeling. However, the authors noticed several issues regarding the consistency of reported data. Therefore, in this work, they analyze the impact of various user defined parameters on simulated direct DNA damage yields. In addition, they draw attention to discrepancies in published literature in DNA strand break (SB) yields and selected methodologies. Methods: The MCTS code Geant4-DNA was used to compare radial dose profiles in a nanometer-scale region of interest (ROI) for photon sources of varying sizes and energies. Then, electron tracks of 0.28 keV–220 keV were superimposed on a geometric DNA model composed of 2.7 × 10 6 nucleosomes, and SBs were simulated according to four definitions based on energy deposits or energy transfers in DNA strand targets compared to a threshold energy E TH . The SB frequencies and complexities in nucleosomes as a function of incident electron energies were obtained. SBs were classified into higher order clusters such as single and double strand breaks (SSBs and DSBs) based on inter-SB distances and on the number of affected strands. Results: Comparisons of different nonuniform dose distributions lacking charged particle equilibrium may lead to erroneous conclusions regarding the effect of energy on relative biological effectiveness. The energy transfer-based SB definitions give similar SB yields as the one based on energy deposit when E TH ≈ 10.79 eV, but deviate significantly for higher E TH values. Between 30 and 40 nucleosomes/Gy show at least one SB in the ROI. The number of nucleosomes that present a complex damage pattern of more than 2 SBs and the degree of complexity of the damage in these nucleosomes diminish as the incident electron energy increases. DNA damage classification into SSB and DSB is highly dependent on the definitions of these higher order structures and their implementations. The authors�

Comparison of Model Calculations of Biological Damage from Exposure to Heavy Ions with Measurements

Science.gov (United States)

Kim, Myung-Hee Y.; Hada, Megumi; Cucinotta, Francis A.; Wu, Honglu

2014-01-01

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X rays, the presence of shielding does not always reduce the radiation risks for energetic charged-particle exposure. Dose delivered by the charged particle increases sharply at the Bragg peak. However, the Bragg curve does not necessarily represent the biological damage along the particle path since biological effects are influenced by the track structures of both primary and secondary particles. Therefore, the ''biological Bragg curve'' is dependent on the energy and the type of the primary particle and may vary for different biological end points. Measurements of the induction of micronuclei (MN) have made across the Bragg curve in human fibroblasts exposed to energetic silicon and iron ions in vitro at two different energies, 300 MeV/nucleon and 1 GeV/nucleon. Although the data did not reveal an increased yield of MN at the location of the Bragg peak, the increased inhibition of cell progression, which is related to cell death, was found at the Bragg peak location. These results are compared to the calculations of biological damage using a stochastic Monte-Carlo track structure model, Galactic Cosmic Ray Event-based Risk Model (GERM) code (Cucinotta, et al., 2011). The GERM code estimates the basic physical properties along the passage of heavy ions in tissue and shielding materials, by which the experimental set-up can be interpreted. The code can also be used to describe the biophysical events of interest in radiobiology, cancer therapy, and space exploration. The calculation has shown that the severely damaged cells at the Bragg peak are more likely to go through reproductive death, the so called "overkill".

Absence of storage effects on radiation damage after thermal neutron irradiation of dry rice seeds

Energy Technology Data Exchange (ETDEWEB)

Kowyama, Y. [Mie Univ., Tsu (Japan); Saito, M.; Kawase, T.

1987-09-15

Storage effects on dry rice seeds equilibrated to 6.8% moisture content were examined after irradiation with X-rays of 5, 10, 20 and 40 kR and with thermal neutrons of 2.1, 4.2, 6.3 and 8.4×10{sup 13}N{sub th}/cm{sup 2}. Reduction in root growth was estimated from dose response curves after storage periods of 1 hr to 21 days. The longer the storage period, the greater enhancement of radiation damages in X-irradiated seeds. There were two components in the storage effect, i. e., a rapid increase of radiosensitivity within the first 24 hr and a slow increase up to 21 days. An almost complete absence of a storage effect was observed after thermal neutron exposure, in spite of considerably high radioactivities of the induced nuclides, {sup 56}Mn, {sup 42}K and {sup 24}Na, which were detected from gamma-ray spectrometry of the irradiated seeds. The present results suggest that the contributions of gamma-rays from the activated nuclides and of inherent contaminating gamma-rays are little or negligible against the neutron-induced damage, and that the main radiobiological effects of thermal neutrons are ascribed to in situ radiations, i, e., heavy particles resulting from neutron-capture reaction of atom. A mechanism underlying the absence of storage effect after thermal neutron irradiation was briefly discussed on the basis of radical formation and decay. (author)

Recent tasks and status of National Research Institute for Radiobiology and Radiohygiene as TSO

International Nuclear Information System (INIS)

Pellet, S.

2007-01-01

The technical support function of the National Research Institute for Radiobiology and Radiohygiene has been introduced at the time of its establishment. In order to support the actual requirements the Institute carries on extended research in the fields of radiation protection and radiation biology participating in national and international projects. Supporting the proper performance of national radiation protection and safety tasks the Institute gives professional directives and expert opinions for decision processes of authorities. The Institutes main areas of radiation protection activity are: - Radiation-related licensing, inspection, record keeping; - assuring safety of radiation sources; - National Personal Dosimetry Service; - radiological monitoring of the environment; - preparedness for radiological incidents and accidents; - radiation protection training activities. The Institute has an accredited Testing Laboratory with nearly sixty examination protocols. Together with its Central Environmental Testing Laboratory, the Institute thus provides a significant support for both theoretical and practical accomplishment of the national radiation protection and safety tasks. (author)

Water versus DNA: new insights into proton track-structure modelling in radiobiology and radiotherapy.

Science.gov (United States)

Champion, C; Quinto, M A; Monti, J M; Galassi, M E; Weck, P F; Fojón, O A; Hanssen, J; Rivarola, R D

2015-10-21

Water is a common surrogate of DNA for modelling the charged particle-induced ionizing processes in living tissue exposed to radiations. The present study aims at scrutinizing the validity of this approximation and then revealing new insights into proton-induced energy transfers by a comparative analysis between water and realistic biological medium. In this context, a self-consistent quantum mechanical modelling of the ionization and electron capture processes is reported within the continuum distorted wave-eikonal initial state framework for both isolated water molecules and DNA components impacted by proton beams. Their respective probability of occurrence-expressed in terms of total cross sections-as well as their energetic signature (potential and kinetic) are assessed in order to clearly emphasize the differences existing between realistic building blocks of living matter and the controverted water-medium surrogate. Consequences in radiobiology and radiotherapy will be discussed in particular in view of treatment planning refinement aiming at better radiotherapy strategies.

The molecular basis of radiosensitivity

International Nuclear Information System (INIS)

McMillan, T.J.

1989-01-01

This paper considers how DNA damage induced by ionising radiation is processed within the cell. The current view of radiobiology is discussed. The author explains the molecular processes that underlie the differences in radiosensitivity

A new radiation biology: epigenetics, exosomes and metabolism

International Nuclear Information System (INIS)

Atkinson, M.J.

2016-01-01

Exposure to ionizing radiation leads to chronic disease, including cancer, cardiovascular disease, neurocognitive deficits and possibly metabolic diseases. The prevailing paradigm of radiation biology considers DNA damage to be the initiating event. Misrepair of initial DNA damage leads to gene mutations that promote clonal expansion and eventually malignancy. However, the paradigm is inconsistent with some recent radiobiological observations

'BioQuaRT' project: design of a novel in situ protocol for the simultaneous visualisation of chromosomal aberrations and micronuclei after irradiation at microbeam facilities

International Nuclear Information System (INIS)

Patrono, C.; Testa, A.; Monteiro Gil, O.; Giesen, U.; Langner, F.; Rabus, H.; Pinto, M.

2015-01-01

The aim of the 'BioQuaRT' (Biologically weighted Quantities in Radiotherapy) project is to develop measurement techniques for characterising charged particle track structure on different length scales, and to correlate at the cellular level the track structure properties with the biological effects of radiation. This multi-scale approach will allow characterisation of the radiation qualities used in radiotherapy and the related biological effects. Charged-particle microbeam facilities were chosen as the platforms for all radiobiology experiments in the 'BioQuaRT' project, because they allow targeting single cells (or compartments of a cell) with a predefined number of ionising particles and correlating the cell-by-cell induced damage with type and energy of the radiation and with the number of ions per cell. Within this project, a novel in situ protocol was developed for the analysis of the mis-repaired and/or unrepaired chromosome damage induced by charged-particle irradiations at the Physikalisch-Technische Bundesanstalt (PTB) ion microbeam facility. Among the cytogenetic biomarkers to detect and estimate radiation-induced DNA damage in radiobiology, chromosomal aberrations and micronuclei were chosen. The characteristics of the PTB irradiation system required the design of a special in situ assay: specific irradiation dishes with a base made from a bio-foil 25-μm thick and only 3000-4000 cells seeded and irradiated per dish. This method was developed on Chinese hamster ovary (CHO) cells, one of the most commonly used cell lines in radiobiology in vitro experiments. The present protocol allows the simultaneous scoring of chromosome aberrations and micronuclei on the same irradiated dish. Thanks to its versatility, this method could also be extended to other radiobiological applications besides the single-ion microbeam irradiations. (authors)

Decontamination activities at the National Institute of Oncology and Radiobiology in Havana, Cuba

International Nuclear Information System (INIS)

Castillo, R.; Salgado, M.; Madrazo, S.; Flores, J.; Marcos, J.

2002-01-01

The National Institute of Oncology and Radiobiology had a facility contaminated with 137 Cs. The contamination was produced by a leaking source stored in the place. First decontamination work was performed in 1988. Some highly contaminated floor tiles and other contaminated items were removed. Spent sealed sources stored in the facility were collected. The facility was closed because of the remaining contamination. As the Regulatory Body allowed the unrestricted use of the facility, decontamination and decommissioning were needed. D and D activities were requested to the CPHR. Contamination surveys conducted in 1999 confirmed the extent of contamination with 137 Cs. Items inside the contaminated area were carefully monitored and segregated. Six Radium sources were recovered. Physical and chemical methods of decontamination were used. For different reasons, the requirements established by the Regulatory Authority for decommissioning could not be achieved, and therefore the facility could not be released from regulatory control. A Radiological Status Report was done explaining the high cost of decontamination according to the established clearance levels. New alternatives were then proposed for decommissioning of this facility. (author)

Long-term radiobiological effects in rats after exposure of 131I in utero

Directory of Open Access Journals (Sweden)

V. V. Talko

2017-12-01

Full Text Available Remote radiobiological effects in male rats prenatally exposed by 131I in different periods of gestation were studied. It was established that the negative effects of irradiation of 131I in utero in the distant period are manifested by disorders of the functioning of the pituitary-thyroid link of endocrine regulation, pro-antioxidant equilibrium, changes in the lipid-lipoprotein spectrum of blood serum. As a result of irradiation of 131I in utero throughout the period of gestation, discoordination in the functioning of the pituitary-thyroid link of endocrine regulation, a violation of the pro-antioxidant balance by increasing the intensity of lipoperoxidation processes and the activity reducing of enzymes of antioxidant defense, the atherogenic orientation of changes in the lipid-lipoprotein spectrum was established. As a result of irradiation by 131I in utero during the third trimester of gestation, the development of hypothyroidism, changes in pro-antioxidant balance due to the activation of antioxidant defense, and the reduction of the concentration of the main classes of lipids have been established.

Role of endothelium in radiation-induced normal tissue damages; Role de l'endothelium dans les dommages radio-induits aux tissus sains

Energy Technology Data Exchange (ETDEWEB)

Milliat, F

2007-05-15

More than half of cancers are treated with radiation therapy alone or in combination with surgery and/or chemotherapy. The goal of radiation therapy is to deliver enough ionising radiation to destroy cancer cells without exceeding the level that the surrounding healthy cells can tolerate. Unfortunately, radiation-induced normal tissue injury is still a dose limiting factor in the treatment of cancer with radiotherapy. The knowledge of normal tissue radiobiology is needed to determine molecular mechanisms involved in normal tissue pathogenic pathways in order to identify therapeutic targets and develop strategies to prevent and /or reduce side effects of radiation therapy. The endothelium is known to play a critical role in radiation-induced injury. Our work shows that endothelial cells promote vascular smooth muscle cell proliferation, migration and fibro-genic phenotype after irradiation. Moreover, we demonstrate for the first time the importance of PAI-1 in radiation-induced normal tissue damage suggesting that PAI-1 may represent a molecular target to limit injury following radiotherapy. We describe a new role for the TGF-b/Smad pathway in the pathogenesis of radiation-induced damages. TGF-b/Smad pathway is involved in the fibro-genic phenotype of VSMC induced by irradiated EC as well as in the radiation-induced PAI-1 expression in endothelial cells. (author)

A method for radiobiological investigations in radiation fields with different LET and high dose rates

International Nuclear Information System (INIS)

Grundler, W.

1976-01-01

For investigations: 1. Performed in the field of radiobiology with different LET-radiation and a relatively high background dose rate of one component (e.g. investigations with fast and intermediate reactor neutrons) 2. Concerning radiation risk studies within a wide range 3. Of irradiations, covering a long time period (up to 100 days) a test system is necessary which on the one hand makes it possible to analyze the influence of different LET radiation and secondly shows a relative radiation resistant behaviour and allows a simple cell cycle regulation. A survey is given upon the installed device of a simple cell observation method, the biological test system used and the analysis of effects caused by dose, repair and LET. It is possible to analyze the behaviour of the nonsurvival cells and to demonstrate different reactions of the test parameters to the radiation of different LET. (author)

Radiogenic isotopes in enriched mid-ocean ridge basalts from Explorer Ridge, northeast Pacific Ocean

Science.gov (United States)

Cousens, Brian; Weis, Dominique; Constantin, Marc; Scott, Steve

2017-09-01

Extreme gradients in topography related to variations in magma supply are observed on the Southern Explorer Ridge (SER), part of the northern Juan de Fuca ridge system. We report radiogenic isotope (Pb, Sr, Nd, Hf) and geochemical data for twenty-four basalt whole-rock and glass samples collected from the length of the SER and from Explorer Deep, a rift to the north of the SER. Lavas from the SER form a north-south geochemical gradient, dominated by E-MORB at the northern axial high, and range from T-MORB to N-MORB towards the southern deepest part of the ridge. Linear relationships between incompatible element ratios and isotopic ratios in MORB along the ridge are consistent with mixing of magmas beneath the ridge to generate the geographic gradient from E- to N-MORB. The E-MORB have high Sr and Pb, and low Nd and Hf isotopic ratios, typical of enriched mantle that includes a FOZO or HIMU isotopic component. The West Valley and Endeavour segments of the northern Juan de Fuca ridge also include this isotopic component, but the proportion of the FOZO or HIMU component is more extreme in the SER basalts. The FOZO or HIMU component may be garnet-bearing peridotite, or a garnet pyroxenite embedded in peridotite. Recycled garnet pyroxenite better explains the very shallow SER axial high, high Nb/La and La/Sm, and the ;enriched; isotopic compositions.

DOE life-span radiation effects studies in experimental animals at University of Utah Division of Radiobiology

International Nuclear Information System (INIS)

Wrenn, M.E.; Taylor, G.N.; Stevens, W.

1986-01-01

The Radiobiology Laboratory at the University of Utah compared the long-term biological effects of 226 Ra and 239 Pu in adult beagles. The program includes the investigation of other radionuclides. More recently, groups of juvenile and aged beagles were added to the study to investigate the influence of age at exposure. These studies involved single intravenous injection of radionuclides to small groups of beagles, in graded doses from levels at which no effects were expected up to levels where a 100% incidence of bone tumors was sometimes found. Some of the principal effects were bone tumors, fractures, and other skeletal alterations observed radiographically and histologically; emphasis was placed on the detection of precancerous changes, hematological changes, and changes related to aging. Emphasis was also placed on metabolic and autoradiographic studies necessary for good radiation dosimetry

Role of endothelium in radiation-induced normal tissue damages; Role de l'endothelium dans les dommages radio-induits aux tissus sains

Energy Technology Data Exchange (ETDEWEB)

Milliat, F

2007-05-15

More than half of cancers are treated with radiation therapy alone or in combination with surgery and/or chemotherapy. The goal of radiation therapy is to deliver enough ionising radiation to destroy cancer cells without exceeding the level that the surrounding healthy cells can tolerate. Unfortunately, radiation-induced normal tissue injury is still a dose limiting factor in the treatment of cancer with radiotherapy. The knowledge of normal tissue radiobiology is needed to determine molecular mechanisms involved in normal tissue pathogenic pathways in order to identify therapeutic targets and develop strategies to prevent and /or reduce side effects of radiation therapy. The endothelium is known to play a critical role in radiation-induced injury. Our work shows that endothelial cells promote vascular smooth muscle cell proliferation, migration and fibro-genic phenotype after irradiation. Moreover, we demonstrate for the first time the importance of PAI-1 in radiation-induced normal tissue damage suggesting that PAI-1 may represent a molecular target to limit injury following radiotherapy. We describe a new role for the TGF-b/Smad pathway in the pathogenesis of radiation-induced damages. TGF-b/Smad pathway is involved in the fibro-genic phenotype of VSMC induced by irradiated EC as well as in the radiation-induced PAI-1 expression in endothelial cells. (author)

SU-F-T-670: From the OR to the Radiobiology Lab: The Journey of a Small X-Ray Source

Energy Technology Data Exchange (ETDEWEB)

Lehmann, J [Calvary Mater, Newcastle, NSW (Australia); The University of Sydney, Sydney, NSW (Australia); The University of Newcastle, Newcastle, NSW (Australia); Barry, M; Jones, R; Fay, M [Calvary Mater, Newcastle, NSW (Australia)

2016-06-15

Purpose: Irradiation of small animal tumor models within laboratories is vital to radiobiological experiments. Often the animals are not able to be brought back into the lab after being taken out for irradiation. Cell biology laboratories benefit from irradiation capability available around the clock without regard to patient load in an associated radiotherapy clinic. Commercial systems are available, but bulky and expensive. Methods: An intraoperative kV irradiation system (IntraBeam™) designed to deliver spherical dose distributions to surgical cavities has been repurposed for the irradiation of cell plates and small laboratory animals. An applicator has been altered to allow for simple, open fields. Special collimators are being developed. BEAMnrc Monte Carlo simulations with the “NRC swept BEAM” source model have been performed to characterize the dose distributions, to develop optimal collimators and as basis for dose prescription. Measurements with radiochromic film and with an ionization chamber were performed to characterize the beam and to validate the simulations. Results: Using its highest setting (50 kV and 40 µA) the x-ray unit is capable of delivering dose rates over 1 Gy/min homogeneously to standard cell plates even without an optimized collimator. Smaller areas (tumors in animals) can be irradiated with significantly higher dose rates (> 20 Gy/min) depending on distance of the source to the tumor. The HVL was found to be 0.21 mm Al which means the shielding requirements for the device are easily achievable in the lab. Conclusion: A mobile irradiation facility is feasible. It will allow easier access to radiation for radiobiology experiments. The modified system is versatile in that for cell plates homogenous irradiations can be achieved through distance from the source, while for high dose rate small field irradiations the source can be brought in close proximity to the target.

Toxicological characteristics and primary radiobiological screening of Cystizid-M

International Nuclear Information System (INIS)

Minkova, M.; Pantev, T.; Georgieva, R.

1987-01-01

The toxic and radioprotective properties of the potential radioprotector of the mollecular combination Cystisid-M (cysteamine-adenosin-5'-monophosphate - CAM) were investigated. The experiments were carried out on male mice C 57 BI irradiated with 137 Cs source. The intraperitoneal administration of 1000 mg/kg b.w. and 500 mg/kg b.w., injected 15 min prior to the irradiation with 8,5 Gr (LD 90/30 ) was performed, and orally 3000 mg/kg b.w. and 1500 mg/kg b.w. was introduced into the stomach 45 min prior to the irradiation with 8,2 Gr (LD 83/30 ). The radioprotective effect of CAM was recorded according to: individual survival curves up to the 30th day; the biometrical coefficients 'ALPHA' (the individual survival expectancy in the population); and S 30 (the group survival expectancy). At the intraperitoneal administration of the protector the values of LD 50 = 1390 mg/kg b.w. and MPD (maximum permissible dose) = 1200 mg/kg b.w. were found. At the oral administration these doses were LD 50/3 = 4630 mg/kg b.w. and MPD = 3500 mg/kg b.w. It was established that CAM injected intraperitoneally in a dose of 1000 mg/kg b.w. ensured 75% survival of the protected mice against 10% of the control ones, increased the mean survival of the deceased and reduced the percentage of the animals died during the height of the bone marrow syndrome. The twofold lower dose exetted a considerably slighter effect. At oral administration the protector did not significantly modify the survival of the animals. The data obtained revealed the perspectiveness of the tested protective agent radiobiological investigations are required

Radiobiological mechanisms of stereotactic body radiation therapy and stereotactic radiation surgery

Energy Technology Data Exchange (ETDEWEB)

Kim, Mi Sook; Kim, Won Woo; Park, In Hwan; Kim, Hee Jong; Lee, Eun Jin; Jung, Jae Hoon [Research Center for Radiotherapy, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Cho, Lawrence Chin Soo; Song, Chang W. [Dept. of Radiation Oncology, University of Minnesota Medical School, Minneapolis (United States)

2015-12-15

Despite the increasing use of stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS) in recent years, the biological base of these high-dose hypo-fractionated radiotherapy modalities has been elusive. Given that most human tumors contain radioresistant hypoxic tumor cells, the radiobiological principles for the conventional multiple-fractionated radiotherapy cannot account for the high efficacy of SBRT and SRS. Recent emerging evidence strongly indicates that SBRT and SRS not only directly kill tumor cells, but also destroy the tumor vascular beds, thereby deteriorating intratumor microenvironment leading to indirect tumor cell death. Furthermore, indications are that the massive release of tumor antigens from the tumor cells directly and indirectly killed by SBRT and SRS stimulate anti-tumor immunity, thereby suppressing recurrence and metastatic tumor growth. The reoxygenation, repair, repopulation, and redistribution, which are important components in the response of tumors to conventional fractionated radiotherapy, play relatively little role in SBRT and SRS. The linear-quadratic model, which accounts for only direct cell death has been suggested to overestimate the cell death by high dose per fraction irradiation. However, the model may in some clinical cases incidentally do not overestimate total cell death because high-dose irradiation causes additional cell death through indirect mechanisms. For the improvement of the efficacy of SBRT and SRS, further investigation is warranted to gain detailed insights into the mechanisms underlying the SBRT and SRS.

Monte Carlo dose calculations and radiobiological modelling: analysis of the effect of the statistical noise of the dose distribution on the probability of tumour control

International Nuclear Information System (INIS)

Buffa, Francesca M.

2000-01-01

The aim of this work is to investigate the influence of the statistical fluctuations of Monte Carlo (MC) dose distributions on the dose volume histograms (DVHs) and radiobiological models, in particular the Poisson model for tumour control probability (tcp). The MC matrix is characterized by a mean dose in each scoring voxel, d, and a statistical error on the mean dose, σ d ; whilst the quantities d and σ d depend on many statistical and physical parameters, here we consider only their dependence on the phantom voxel size and the number of histories from the radiation source. Dose distributions from high-energy photon beams have been analysed. It has been found that the DVH broadens when increasing the statistical noise of the dose distribution, and the tcp calculation systematically underestimates the real tumour control value, defined here as the value of tumour control when the statistical error of the dose distribution tends to zero. When increasing the number of energy deposition events, either by increasing the voxel dimensions or increasing the number of histories from the source, the DVH broadening decreases and tcp converges to the 'correct' value. It is shown that the underestimation of the tcp due to the noise in the dose distribution depends on the degree of heterogeneity of the radiobiological parameters over the population; in particular this error decreases with increasing the biological heterogeneity, whereas it becomes significant in the hypothesis of a radiosensitivity assay for single patients, or for subgroups of patients. It has been found, for example, that when the voxel dimension is changed from a cube with sides of 0.5 cm to a cube with sides of 0.25 cm (with a fixed number of histories of 10 8 from the source), the systematic error in the tcp calculation is about 75% in the homogeneous hypothesis, and it decreases to a minimum value of about 15% in a case of high radiobiological heterogeneity. The possibility of using the error on the

Radiobiological evaluation of the radiation dose as used in high-precision radiotherapy. Effect of prolonged delivery time and applicability of the linear-quadratic model

International Nuclear Information System (INIS)

Shibamoto, Yuta; Otsuka, Shinya; Iwata, Hiromitsu; Sugie, Chikao; Ogino, Hiroyuki; Tomita, Natsuo

2012-01-01

Since the dose delivery pattern in high-precision radiotherapy is different from that in conventional radiation, radiobiological assessment of the physical dose used in stereotactic irradiation and intensity-modulated radiotherapy has become necessary. In these treatments, the daily dose is usually given intermittently over a time longer than that used in conventional radiotherapy. During prolonged radiation delivery, sublethal damage repair takes place, leading to the decreased effect of radiation. This phenomenon is almost universarily observed in vitro. In in vivo tumors, however, this decrease in effect can be counterbalanced by rapid reoxygenation, which has been demonstrated in a laboratory study. Studies on reoxygenation in human tumors are warranted to better evaluate the influence of prolonged radiation delivery. Another issue related to radiosurgery and hypofractionated stereotactic radiotherapy is the mathematical model for dose evaluation and conversion. Many clinicians use the linear-quadratic (LQ) model and biologically effective dose (BED) to estimate the effects of various radiation schedules, but it has been suggested that the LQ model is not applicable to high doses per fraction. Recent experimental studies verified the inadequacy of the LQ model in converting hypofractionated doses into single doses. The LQ model overestimates the effect of high fractional doses of radiation. BED is particularly incorrect when it is used for tumor responses in vivo, since it does not take reoxygenation into account. For normal tissue responses, improved models have been proposed, but, for in vivo tumor responses, the currently available models are not satisfactory, and better ones should be proposed in future studies. (author)

Cardiac endothelial cells isolated from mouse heart - a novel model for radiobiology

International Nuclear Information System (INIS)

Jelonek, K.; Walaszczyk, A.; Gabrys, D.; Pietrowska, M.; Widlak, P.; Kanthou, Ch.

2011-01-01

Cardiovascular disease is recognized as an important clinical problem in radiotherapy and radiation protection. However, only few radiobiological models relevant for assessment of cardiotoxic effects of ionizing radiation are available. Here we describe the isolation of mouse primary cardiac endothelial cells, a possible target for cardiotoxic effects of radiation. Cells isolated from hearts of juvenile mice were cultured and irradiated in vitro. In addition, cells isolated from hearts of locally irradiated adult animals (up to 6 days after irradiation) were tested. A dose-dependent formation of histone γH 2 A.X foci was observed after in vitro irradiation of cultured cells. However, such cells were resistant to radiation-induced apoptosis. Increased levels of actin stress fibres were observed in the cytoplasm of cardiac endothelial cells irradiated in vitro or isolated from irradiated animals. A high dose of 16 Gy did not increase permeability to Dextran in monolayers formed by endothelial cells. Up-regulated expression of Vcam1, Sele and Hsp70i genes was detected after irradiation in vitro and in cells isolated few days after irradiation in vivo. The increased level of actin stress fibres and enhanced expression of stress-response genes in irradiated endothelial cells are potentially involved in cardiotoxic effects of ionizing radiation. (authors)

Development of a single ion micro-irradiation facility for experimental radiobiology at cell level

International Nuclear Information System (INIS)

Barberet, Ph.

2003-10-01

A micro-irradiation device has been developed for radiobiology applications at the scale of the cell. This device is based on an upgrade of an existing micro-beam line that was already able to deliver a 1 to 3 MeV proton or alpha beam of low intensity and whose space resolution is lower than 1 micrometer in vacuum. The important part of this work has been the development of an irradiation stage designed to fit on the micro-probe and able to deliver ions in the air with an absolute accuracy of a few micrometers. A program has been set up to monitor the complete irradiation line in testing and in automatic irradiation operating phases. Simulation tools based on Monte-Carlo calculations have been validated through comparisons with experimental data particularly in the field of spatial resolution and of the number of ions delivered. The promising results show the possibility in a near future to use this tool to study the response of cells to very low irradiation doses down to the extreme limit of one ion per cell

Radiogenic isotope evidence for transatlantic atmospheric dust transport

Science.gov (United States)

Kumar, Ashwini; Abouchami, Wafa; Garrison, Virginia H.; Galer, Stephen J. G.; Andreae, Meinrat O.

2013-04-01

Early studies by Prospero and colleagues [1] have shown that African dust reaches all across the Atlantic and into the Caribbean. It may contribute to fertilizing the Amazon rainforest [2,3,4], in addition to enhancing the ocean biological productivity via delivery of iron, a key nutrient element[5]. Radiogenic isotope ratios (Sr, Nd, Pb) are robust tracers of dust sources and can thus provide information on provenance and pathways of dust transport. Here we report Sr, Nd and Pb isotope data on atmospheric aerosols, collected in 2008 on quartz filters, from three different locations in Mali (12.6° N, 8.0° W; 555 m a.s.l.), Tobago (11.3° N, 60.5° W; 329 m a.s.l.) and the U.S. Virgin Islands (17.7° N, 64.6° W; 27 m a.s.l.) to investigate the hypothesis of dust transport across the Atlantic. About 2 cm2 of filter were acid-leached in 0.5 N HBr for selective removal of the anthropogenic labile Pb component (leachate) and possibly the fine soluble particle fraction. The remainder of the filter was subsequently dissolved using a mixture of HF and HNO3 acids, and should be representative of the silicate fraction. Isotopic compositions were measured by TIMS on a ThermoFisher Triton at MPIC, with Pb isotope ratios determined using the triple-spike method. Significant Pb isotope differences between leachates and residues were observed. The variability in Pb isotopic composition among leachates may be attributed to variable and distinct anthropogenic local Pb sources from Africa and South America [6], however, residues are imprinted by filter blank contribution suggesting to avoid the quartz fiber filter for isotopic study of aerosols. The Nd and Sr isotope ratios of aerosol leachates show similar signatures at all three locations investigated. The nearly identical Nd and Sr isotopic compositions in the Mali, Tobago and Virgin islands leachates are comparable to those obtained on samples from the Bodélé depression, Northern Chad [7] and suggest a possible common

Radiation damage prediction system using damage function

International Nuclear Information System (INIS)

Tanaka, Yoshihisa; Mori, Seiji

1979-01-01

The irradiation damage analysis system using a damage function was investigated. This irradiation damage analysis system consists of the following three processes, the unfolding of a damage function, the calculation of the neutron flux spectrum of the object of damage analysis and the estimation of irradiation effect of the object of damage analysis. The damage function is calculated by applying the SAND-2 code. The ANISN and DOT3, 5 codes are used to calculate neutron flux. The neutron radiation and the allowable time of reactor operation can be estimated based on these calculations of the damage function and neutron flux. The flow diagram of the process of analyzing irradiation damage by a damage function and the flow diagram of SAND-2 code are presented, and the analytical code for estimating damage, which is determined with a damage function and a neutron spectrum, is explained. The application of the irradiation damage analysis system using a damage function was carried out to the core support structure of a fast breeder reactor for the damage estimation and the uncertainty evaluation. The fundamental analytical conditions and the analytical model for this work are presented, then the irradiation data for SUS304, the initial estimated values of a damage function, the error analysis for a damage function and the analytical results are explained concerning the computation of a damage function for 10% total elongation. Concerning the damage estimation of FBR core support structure, the standard and lower limiting values of damage, the permissible neutron flux and the allowable years of reactor operation are presented and were evaluated. (Nakai, Y.)

Pacific Northwest Laboratory annual report for 1994 to the DOE Office of Energy Research Part 1: Biomedical sciences

Energy Technology Data Exchange (ETDEWEB)

Park, J.F.

1995-04-01

Research in the biomedical sciences at PNL is described. Activities reported include: inhaled plutonium in dogs; national radiobiology archives; statistical analysis of data from animal studies; genotoxicity of inhaled energy effluents; molecular events during tumor initiation; biochemistry of free radical induced DNA damage; radon hazards in homes; mechanisms of radon injury; genetics of radon induced lung cancer; and in vivo/in vitro radon induced cellular damage.

Analysis of a large number of clinical studies for breast cancer radiotherapy: estimation of radiobiological parameters for treatment planning

International Nuclear Information System (INIS)

Guerrero, M; Li, X Allen

2003-01-01

Numerous studies of early-stage breast cancer treated with breast conserving surgery (BCS) and radiotherapy (RT) have been published in recent years. Both external beam radiotherapy (EBRT) and/or brachytherapy (BT) with different fractionation schemes are currently used. The present RT practice is largely based on empirical experience and it lacks a reliable modelling tool to compare different RT modalities or to design new treatment strategies. The purpose of this work is to derive a plausible set of radiobiological parameters that can be used for RT treatment planning. The derivation is based on existing clinical data and is consistent with the analysis of a large number of published clinical studies on early-stage breast cancer. A large number of published clinical studies on the treatment of early breast cancer with BCS plus RT (including whole breast EBRT with or without a boost to the tumour bed, whole breast EBRT alone, brachytherapy alone) and RT alone are compiled and analysed. The linear quadratic (LQ) model is used in the analysis. Three of these clinical studies are selected to derive a plausible set of LQ parameters. The potential doubling time is set a priori in the derivation according to in vitro measurements from the literature. The impact of considering lower or higher T pot is investigated. The effects of inhomogeneous dose distributions are considered using clinically representative dose volume histograms. The derived LQ parameters are used to compare a large number of clinical studies using different regimes (e.g., RT modality and/or different fractionation schemes with different prescribed dose) in order to validate their applicability. The values of the equivalent uniform dose (EUD) and biologically effective dose (BED) are used as a common metric to compare the biological effectiveness of each treatment regime. We have obtained a plausible set of radiobiological parameters for breast cancer. This set of parameters is consistent with in vitro

Fractionated homogenous total-body irradiation prior to bone marrow transplantation

Energy Technology Data Exchange (ETDEWEB)

Duehmke, E; Brix, F; Hebbinghaus, D; Jensen, M; Wendhausen, H; Schmitz, N

1985-03-01

At the University of Kiel, myeloid and acute lymphatic leukemia is treated since 1983 by total-body irradiation applied prior to bone marrow transplantation. Dose deviations in the midplane caused by the irregular surface and tissue inhomogeneities of the patient are reduced down to +-3.5% compared to the central ray, with the help of CT-based individual compensators. This method prevents above all an excessive dose to the lungs. The radiobiologic advantages of fractionated irradiation have been employed for all patients treated hitherto (n = 9). At present, a total body dose of 12 Gy in six fractions is applied within three days. There were no undesired acute radiogenic reactions except a mild acute mucositis found in all patients. Chronic side effects, especially in the lungs, were not demonstrated, too. However, the average follow-up time of 149 days has been rather short. One patient died from relapse of leukemia after a total dose of 10 Gy, another patient died because the transplanted bone marrow was rejected, and a third died from catheter sepsis. Six out of nine patients are in complete remission with a maximum index of Karnofsky. The limited experiences gained hitherto show that the homogeneous accelerated-fractionated total-body irradiation offers essential advantages compared to non-compensated single dose irradiation with respect to the prevention of undesired radiogenic effects in sound tissues and that its therapeutic efficacy is at least the same.

Radiobiological waste treatment-ashing treatment and immobilization with cement

Energy Technology Data Exchange (ETDEWEB)

Shengtao, Feng; Li, Gong; Li, Cheng; Benli, Wang; Lihong, Wang [China Inst. for Radiation Protection, Taiyuan, Shanxi (China)

1997-02-01

This report describes the results of the study on the treatment of radioactive biological waste in the China Institute for Radiation Protection (CIRP). The possibility of radiobiological waste treatment was investigated by using a RAF-3 type rapid ashing apparatus together with the immobilization of the resulted ash. This rapid ashing apparatus, developed by CIRP, is usually used for pretreatment of samples prior to chemical analysis and physical measurements. The results show that it can ash 3 kg of animal carcasses a batch, the ashing time is 5-7 h and the ash content is less than 4 wt%. The ashing temperature not exceeding 450 deg. C was used without any risk of high losses of radionuclides. The ash from the rapid ashing apparatus was demonstrated to be immobilized with ordinary silicate cement. The optimum cement/ash/water formulation of the cemented waste form was 35 {+-} 5 wt% cement, 29 {+-} 2 wt% water, and 36 {+-} 6 wt% ash. The performance of the waste form was in compliance with the technical requirements except for impact resistance. Mixing additives in immobilization formulations can improve the performance of the cemented ash waste form. The additives chosen were DH{sub 4A} flow promoter as a cement additive and vermiculite or zeolite as a supplement. The recommended formulation, i.e. an improved formulation of the cemented ash waste form is that additives DH{sub 4A} flow promoter and vermiculite (or zeolite) are added on the ground of optimum cement/ash/water formulation of the cemented waste form, the dosage of water, DH{sub 4A} and vermiculite (or zeolite) is 70 wt%, 0.5 wt% and {<=} 5 wt% of the cement dosage, respectively. The cemented ash waste forms obtained meet all the requirements for disposal. (author). 12 refs, 7 figs, 13 tabs.

Radiobiological waste treatment-ashing treatment and immobilization with cement

International Nuclear Information System (INIS)

Feng Shengtao; Gong Li; Cheng Li; Wang Benli; Wang Lihong

1997-01-01

This report describes the results of the study on the treatment of radioactive biological waste in the China Institute for Radiation Protection (CIRP). The possibility of radiobiological waste treatment was investigated by using a RAF-3 type rapid ashing apparatus together with the immobilization of the resulted ash. This rapid ashing apparatus, developed by CIRP, is usually used for pretreatment of samples prior to chemical analysis and physical measurements. The results show that it can ash 3 kg of animal carcasses a batch, the ashing time is 5-7 h and the ash content is less than 4 wt%. The ashing temperature not exceeding 450 deg. C was used without any risk of high losses of radionuclides. The ash from the rapid ashing apparatus was demonstrated to be immobilized with ordinary silicate cement. The optimum cement/ash/water formulation of the cemented waste form was 35 ± 5 wt% cement, 29 ± 2 wt% water, and 36 ± 6 wt% ash. The performance of the waste form was in compliance with the technical requirements except for impact resistance. Mixing additives in immobilization formulations can improve the performance of the cemented ash waste form. The additives chosen were DH 4A flow promoter as a cement additive and vermiculite or zeolite as a supplement. The recommended formulation, i.e. an improved formulation of the cemented ash waste form is that additives DH 4A flow promoter and vermiculite (or zeolite) are added on the ground of optimum cement/ash/water formulation of the cemented waste form, the dosage of water, DH 4A and vermiculite (or zeolite) is 70 wt%, 0.5 wt% and ≤ 5 wt% of the cement dosage, respectively. The cemented ash waste forms obtained meet all the requirements for disposal. (author). 12 refs, 7 figs, 13 tabs

Biochemical and Radiobiological Factors in the Early Detection of Radiation Injury in Mammals

Energy Technology Data Exchange (ETDEWEB)

Cole, L. J. [Life Sciences Division, Stanford Research Institute, Menlo Park, CA (United States)

1971-03-15

In considering the body of radiobiological knowledge upon which the present possibilities for the development of an objective quantitative laboratory procedure for early detection of radiation injury depend, it is evident that there are at least three general categories of radiation effects which are relevant to this objective: (1) Products of the enzymatic-chemical breakdown of macromolecules, and lysis of killed or dying cells from radiosensitive tissues, for example deoxypolynucleotides from lymphoid tissues and bone marrow; (2) Radiation-induced inhibition of synthesis of deoxyribonucleic acid (DNA) and/or other macromolecules, eliciting alterations in tissue and blood concentrations and pool size of metabolic intermediates in the synthesis, for example, deoxycytidine; (3) Radiation-induced alterations, suppression, or cessation of specialized cell function; of particular interest here is the immunological functions of lymphocytes, including those in the circulating blood. For rodents, the exquisite radiosensitivity of bone-marrow-stem cells as well as of lymphocytes has been precisely measured by modern cellular radiobiological techniques: the colony-forming technique of Till and McCulloch, yielding a D{sub 0} for bone-marrow cells of about 80 R; and the graft-versus-host reactivity of transplanted lymphocytes yielding a similar D{sub 0} value. In our own hands, a modified colony-formation technique for dog bone-marrow cells irradiated in.vitro and in vivo give D{sub 0} values of {approx}100 R. Thus, on the basis of radiation sensitivity and the time-relationships for interphase cell death for lymphocytes, it appears that this cell class is probably the best ''candidate'' source for an early radiation-injury detection system. However,- the important report by Zicha and Buric indicates that extrapolation of biochemical data on radiation dosimetry from rodents to man is not necessarily feasible, at least in the. case of the urinary excretion of deoxycytidine

Radiogenic responses of normal cells induced by fractionated irradiation -a simulation study. Pt. 2. Late responses

International Nuclear Information System (INIS)

Duechting, W.; Ulmer, W.; Ginsberg, T.; Kikhounga-N'Got, O.; Saile, C.

1995-01-01

Based on controlled theory, a computed simulation model has been constructed which describes the time course of slowly responding normal cells after irradiation exposure. Subsequently, different clinical irradiation schemes are compared in regard to their delayed radiogenic responses referred to as late effects in radiological terminology. A cybernetic model of a paraenchymal tissue consisting of dominantly resting functional cells has been developed and transferred into a computer model. The radiation effects are considered by characteristic cell parameters as well as by the linear-quadratic model. Three kinds of tissue (brain and lung parenchym of the mouse, liver parenchym of rat) have been irradiated in the model according to standard-, super-, hyperfractionation and a single high dose per week. The simulation studies indicate that the late reaction of brain parenchym to hyperfractionation (3 x 1.5 Gy per day) and of lung parenchym tissue with regard to all fractionation schemes applied is particularly severe. The behavior of liver parenchym is not unique. A comparison of the simulation results basing to the survival of cell numbers with clinical experience and practice shows that the clinical reality can qualitatively be represented by the model. This opens the door for connecting side effects to normal tissue with the corresponding tumor efficacy (discussed in previous papers). The model is open to further refinement and to discussions referring to the phenomenon of late effects. (orig.) [de

Meson radiobiology and therapy

International Nuclear Information System (INIS)

Kilgerman, M.M.

1975-08-01

High-linear energy transfer radiation (neutrons, heavy ions, and pions) have a greater relative biological effectiveness than low-linear energy transfer radiation by depositing a high density of ionization in irradiated cells. This overcomes the protective effect of oxygen; decreases the variation in sensitivity among the several stages of the cell cycles; and, inhibits the repair of sublethal damage as compared to x-rays, gamma rays, electrons and protons. Negative pi mesons (pions), appear particularly suited for radiation therapy as their penetration and depth-dose profiles lend themselves to shaping the high dose area to the tumor size and location. Preliminary biological experiments with pions produced at the Los Alamos Meson Physics Facility studied cell survival at various radiation depths and cell cycle sensitivity. Histologic study of data from the first human experiments indicated severe tumor cell destruction by pions as compared to x-rays in treating malignant melanoma skin nodules, without increased effects on dermal elements. (U.S.)

Some aspects of the mechanism of bacteriophage function. Final progress report

International Nuclear Information System (INIS)

Freifelder, D.

1977-01-01

Data are summarized from a ten-year study on the radiobiology of phages. The results showed that: phages are inactivated principally by damage to DNA; DNA damage is of two types, base damage and double-strand breakage; double-strand breakage may be lethal because of interruption within a gene, however in phage systems the damage is more fundamental in that only a single DNA fragment is injected into the host; E. coli phage T4 is relatively resistant to inactivation by x-rays; and the rate of production of strand breaks and base damage is nearly the same in bacteriophage and bacteria

Effects of ionizing radiation and the molecular and cellular mechanisms

International Nuclear Information System (INIS)

1982-01-01

This symposium with its 60 contributions presents a survey of the current state of the art in molecular radiation biophysics and radiobiology in the FRG. Many contributions show the trend of applying findings in these fields to cancer research. The various sessions have been devoted to: 1) Radiation chemistry of biomolecules; 2) DNA damage and repair; 3) Repair of DNA damage; 4) Cell proliferation and cell inactivation; 5) Cancerogenesis, mutation and chromosomal damage; 6) Effects of heavy ions. (AJ) [de

Cellular radiobiology of heavy-ion beams

International Nuclear Information System (INIS)

Tobias, C.A.; Blakely, E.A.; Ngo, F.Q.H.; Roots, R.J.; Yang, T.C.

1981-01-01

Progress is reported in the following areas of this research program: relative biological effectiveness and oxygen enhancement ratio of silicon ion beams; heavy ion effects on the cell cycle; the potentiation effect (2 doses of high LET heavy-ion radiations separated by 2 to 3 hours); potentially lethal damage in actively growing cells and plateau growth cells; radiation induced macromolecular lesions and cellular radiation chemistry; lethal effects of dual radiation; and the development of a biophysical repair/misrepair model

Dosimetry and radiobiology at the new RA-3 reactor boron neutron capture therapy (BNCT) facility: Application to the treatment of experimental oral cancer

Energy Technology Data Exchange (ETDEWEB)

Pozzi, E. [Research and Production Reactors, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina)], E-mail: epozzi@cnea.gov.ar; Nigg, D.W. [Idaho National Laboratory, Idaho Falls (United States); Miller, M.; Thorp, S.I. [Instrumentation and Control Department, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Heber, E.M. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina); Zarza, L.; Estryk, G. [Research and Production Reactors, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Monti Hughes, A.; Molinari, A.J.; Garabalino, M. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina); Itoiz, M.E. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina); Department of Oral Pathology, Faculty of Dentistry, University of Buenos Aires (Argentina); Aromando, R.F. [Department of Oral Pathology, Faculty of Dentistry, University of Buenos Aires (Argentina); Quintana, J. [Research and Production Reactors, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Trivillin, V.A.; Schwint, A.E. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina)

2009-07-15

The National Atomic Energy Commission of Argentina (CNEA) constructed a novel thermal neutron source for use in boron neutron capture therapy (BNCT) applications at the RA-3 research reactor facility located in Buenos Aires. The aim of the present study was to perform a dosimetric characterization of the facility and undertake radiobiological studies of BNCT in an experimental model of oral cancer in the hamster cheek pouch. The free-field thermal flux was 7.1x10{sup 9} n cm{sup -2} s{sup -1} and the fast neutron flux was 2.5x10{sup 6} n cm{sup -2} s{sup -1}, indicating a very well-thermalized neutron field with negligible fast neutron dose. For radiobiological studies it was necessary to shield the body of the hamster from the neutron flux while exposing the everted cheek pouch bearing the tumors. To that end we developed a lithium (enriched to 95% in {sup 6}Li) carbonate enclosure. Groups of tumor-bearing hamsters were submitted to BPA-BNCT, GB-10-BNCT, (GB-10+BPA)-BNCT or beam only treatments. Normal (non-cancerized) hamsters were treated similarly to evaluate normal tissue radiotoxicity. The total physical dose delivered to tumor with the BNCT treatments ranged from 6 to 8.5 Gy. Tumor control at 30 days ranged from 73% to 85%, with no normal tissue radiotoxicity. Significant but reversible mucositis in precancerous tissue surrounding tumors was associated to BPA-BNCT. The therapeutic success of different BNCT protocols in treating experimental oral cancer at this novel facility was unequivocally demonstrated.

Dosimetry and radiobiology at the new RA-3 reactor boron neutron capture therapy (BNCT) facility: Application to the treatment of experimental oral cancer

International Nuclear Information System (INIS)

Pozzi, E.; Nigg, D.W.; Miller, M.; Thorp, S.I.; Heber, E.M.; Zarza, L.; Estryk, G.; Monti Hughes, A.; Molinari, A.J.; Garabalino, M.; Itoiz, M.E.; Aromando, R.F.; Quintana, J.; Trivillin, V.A.; Schwint, A.E.

2009-01-01

The National Atomic Energy Commission of Argentina (CNEA) constructed a novel thermal neutron source for use in boron neutron capture therapy (BNCT) applications at the RA-3 research reactor facility located in Buenos Aires. The aim of the present study was to perform a dosimetric characterization of the facility and undertake radiobiological studies of BNCT in an experimental model of oral cancer in the hamster cheek pouch. The free-field thermal flux was 7.1x10 9 n cm -2 s -1 and the fast neutron flux was 2.5x10 6 n cm -2 s -1 , indicating a very well-thermalized neutron field with negligible fast neutron dose. For radiobiological studies it was necessary to shield the body of the hamster from the neutron flux while exposing the everted cheek pouch bearing the tumors. To that end we developed a lithium (enriched to 95% in 6 Li) carbonate enclosure. Groups of tumor-bearing hamsters were submitted to BPA-BNCT, GB-10-BNCT, (GB-10+BPA)-BNCT or beam only treatments. Normal (non-cancerized) hamsters were treated similarly to evaluate normal tissue radiotoxicity. The total physical dose delivered to tumor with the BNCT treatments ranged from 6 to 8.5 Gy. Tumor control at 30 days ranged from 73% to 85%, with no normal tissue radiotoxicity. Significant but reversible mucositis in precancerous tissue surrounding tumors was associated to BPA-BNCT. The therapeutic success of different BNCT protocols in treating experimental oral cancer at this novel facility was unequivocally demonstrated.

Abstracts of papers of international scientific conference 'Fundamental and applied aspects of radiobiology: Biological effects of low doses and radioactive contamination of environment (Radioecological and medical biological consequences of the Chernobyl NPP accident)'

International Nuclear Information System (INIS)

Konoplya, E.F.; Astakhov, A.I.; Bogdevich, I.M.; Borisevich, N.Ya.; Zubovich, V.K.; Knat'ko, V.A.; Lobanok, L.M.; Matsko, V.P.; Mrochek, A.G.

1998-05-01

The results of research works executed in Belarus, as well as in Ukraine and Russia, on various aspects of the Chernobyl problematic are given: radiation medicine and risks, radiobiological effects and their forecasting, radioecology and agricultural radiology, decontamination and radioactive wastes management, socio economic and psychological problems caused by the Chernobyl NPP accident

Brachytherapy optimization using radiobiological-based planning for high dose rate and permanent implants for prostate cancer treatment

Science.gov (United States)

Seeley, Kaelyn; Cunha, J. Adam; Hong, Tae Min

2017-01-01

We discuss an improvement in brachytherapy--a prostate cancer treatment method that directly places radioactive seeds inside target cancerous regions--by optimizing the current standard for delivering dose. Currently, the seeds' spatiotemporal placement is determined by optimizing the dose based on a set of physical, user-defined constraints. One particular approach is the ``inverse planning'' algorithms that allow for tightly fit isodose lines around the target volumes in order to reduce dose to the patient's organs at risk. However, these dose distributions are typically computed assuming the same biological response to radiation for different types of tissues. In our work, we consider radiobiological parameters to account for the differences in the individual sensitivities and responses to radiation for tissues surrounding the target. Among the benefits are a more accurate toxicity rate and more coverage to target regions for planning high-dose-rate treatments as well as permanent implants.

Metabolite Damage and Metabolite Damage Control in Plants

Energy Technology Data Exchange (ETDEWEB)

Hanson, Andrew D. [Horticultural Sciences Department and; Henry, Christopher S. [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, Illinois 60439, email:; Computation Institute, University of Chicago, Chicago, Illinois 60637; Fiehn, Oliver [Genome Center, University of California, Davis, California 95616, email:; de Crécy-Lagard, Valérie [Microbiology and Cell Science Department, University of Florida, Gainesville, Florida 32611, email: ,

2016-04-29

It is increasingly clear that (a) many metabolites undergo spontaneous or enzyme-catalyzed side reactions in vivo, (b) the damaged metabolites formed by these reactions can be harmful, and (c) organisms have biochemical systems that limit the buildup of damaged metabolites. These damage-control systems either return a damaged molecule to its pristine state (metabolite repair) or convert harmful molecules to harmless ones (damage preemption). Because all organisms share a core set of metabolites that suffer the same chemical and enzymatic damage reactions, certain damage-control systems are widely conserved across the kingdoms of life. Relatively few damage reactions and damage-control systems are well known. Uncovering new damage reactions and identifying the corresponding damaged metabolites, damage-control genes, and enzymes demands a coordinated mix of chemistry, metabolomics, cheminformatics, biochemistry, and comparative genomics. This review illustrates the above points using examples from plants, which are at least as prone to metabolite damage as other organisms.

Whole planet cooling and the radiogenic heat source contents of the earth and moon

International Nuclear Information System (INIS)

Schubert, G.; Stevenson, D.

1980-01-01

It is widely believed that the surface heat flows of the earth and moon provide good measures of the total amounts of radioactives in these bodies. Simple thermal evolution models, based on subsolidus whole mantle convection, indicate that this may not be the case. These models have been constructed assuming an initially hot state, but with a wide variety of choices for the parameters characterizing the rheology and convective vigor. All models are constrained to be consistent with present-day surface heat fluxes, and many of the terrestrial models are consistent with the mantle viscosities indicated by post-glacial rebound. For the earth the acceptable models give a radiogenic heat production that is only 65--85% of the surface heat output, the difference being due to secular cooling of the earth (about 50 0 --100 0 C per 10 9 years in the upper mantle). It is argued that the actual heat generation may be substantially less, since the models omit core heat, upward migration of heat sources, possible layering of the mantle, and deviations from steady convection. Geochemical models which are near to chondritic (apart from potassium depletion) are marginally consistent with surface heat flow. In the lunar models, heat generation is typically only 70--80% of the surface heat flow, even with allowance for the strong near-surface enhancement of radioactives. Despite the simplicity of the models the persistence of a significant difference between heat generation and heat output for a wide range of parameter choices indicates that this difference is real and should be incorporated in geochemical modeling of the planets

Radiobiologically based assessments of the net costs of fractionated radiotherapy

International Nuclear Information System (INIS)

Dale, Roger G.; Jones, Bleddyn

1996-01-01

Purpose: To examine how the long-term costs of radiation therapy may be influenced by modifications to fractionation schemes, and how any improvements in tumor control might, in principle, be translated into a potential cost saving for the responsible healthcare organization. Methods and Materials: Standard radiobiological modeling based on the linear-quadratic (LQ) model is combined with financial parameters relating to the estimated costs of different aspects of radiotherapy treatment delivery. The cost model includes provision for the long-term costs of treatment failure and enables the extra costs of near optimal radiotherapy to be balanced against suboptimal alternatives, which are more likely to be associated with further radiotherapy, salvage surgery, and continuing care. Results: A number of caveats are essential in presenting a model such as this for the first time, and these are clearly stated. However, a recurring observation is that, in terms of the whole cost of supporting a patient from first radiotherapy treatment onwards, high quality radiotherapy (i.e., based on individual patterns of fractionation that are near optimal for particular subpopulations of tumor) will frequently be associated with the lowest global cost. Conclusions: This work adds weight to the case for identifying fast and accurate predictive assay techniques, and supports the argument that suboptimal radiotherapy is usually more costly in the long term. Although the article looks only at the cost-benefit consequences of altered patterns of fractionation, the method will, in principle, have application to other changes in the way radiotherapy can be performed, e.g., to examining the cost-benefit aspects of tumor dose escalation as a consequence of using advanced conformal treatment planning

AFRRI (Armed Forces Radiobiology Research Institute) reports, April, May, June 1987. Technical report

Energy Technology Data Exchange (ETDEWEB)

1987-07-01

This document is a collection of reprinted technical reports. Partial contents include: Effect of ionizing radiation on prostaglandins and gastric secretion in rhesus monkeys; Characterization of rat prothymocyte with monoclonal antibodies recognizing rat lymphocyte membrane antigenic determinants; Effects of subdiaphragmatic vagotomy on the acquisition of a radiation-induced condition taste aversion; Ethanol-induced taste aversions; Lack of involvement of acetaldehyde and the area postrema; Dose and time relationships of the radioprotector WR-2721 on locomotor activity in mice; Purification and analysis of rat hematopoietic stem cells by flow cytometry, Plasma histamine and catecholamine levels during hypotension induced by morphine and compound 48/80; Effects of ionizing radiation on hippocampal excitability, Tumor necrosis factor/cachectin is a less-potent inducer of serum amyloid A synthesis than interleukin 1, Protection of mice against fission-neutron irradiation by WR-2721 or WR-151327, Induction of colony-stimulating factor in vivo by recombinant interleukin 1 a and recombinant tumor necrosis factor alpha; 16,16-Dimethyl prostaglandin E2 increases survival in mice following irradiation, Selenium pretreatment enhances the radioprotective effect and reduces the lethal toxicity of WR-2721; Rat phantom depth dose studies in electron, x-ray, gamma-ray, and reactor-radiation fields; Wall attenuation and scatter characteristics of ionization chambers at Armed Forces Radiobiology Research Institute.

Radiobiological characterization of different energy-photon beams used in radiotherapy from linear accelerator

International Nuclear Information System (INIS)

Elata, A.; Hassan, A. M. E.; Ali, E.; Calzolari, P.; Bettega, D.

2009-02-01

The main objective of this study was to perform a radiobiological characterization of different energy photon beams (6 MV and 15 MV) from linear accelerator used in radiotherapy, and comparison of different treatment modalities, with special regard to late effects of radiation. Using two end points, cell survival and micronucleus induction, in the biological system (Chines hamster V79 cell line). Chromosomes number was counted and found to be 22 chromosomes per cell. Cells were kept in confluent growth for two days and then exposed to two photon beams and immediately after irradiation were counted and re seeded in different numbered for each dose. For evaluation of surviving fraction samples were incubated at 37o C for 6 days, five samples were counted for each dose. At the same time three samples were seeded for the micronuclei frequency and incubated at 37o C after 24 hours cytochalasin-B was added to block cells in cytokinesis. The survival curve showed similar curves for the two beams and decreased with dose. The micronuclei frequency was positively correlated with dose and the energy of the photon. This indicates the presence of low dose of photoneutrons produced by using high energy photon beams. (Author)

The Chernobyl accident: possible pathogenic mechanisms of origination of psychical and psychosomatic disadaptation

International Nuclear Information System (INIS)

Gelda, A.P

1998-01-01

The impact of the social-psychological and biological (low doze chronic irradiation, foods unbalance, local ecological hazards) factors increase a degree of pathogen influence on organism. It is known that chronic irradiation by low dozes promotes to an increase of sensitivity to damaging action other pathogenic factors. At the same time at the special functional condition (for example, stresses), radiosensitivity of organism and a number of non radiobiological agents in combined action with radiation enhances the radiobiological effect of irradiation. Predisposing factors have a certain significance. Taking into account a real social-psychological situation the problem of medico-biological consequences of the Chernobyl accident gets the special social-medical importance

Imperfect conformation of experimental and epidemiological data for frequency of RET/РТС gene rearrangements in papillary thyroid carcinoma for the Chernobyl accident

Directory of Open Access Journals (Sweden)

Ushenkova L.N.

2013-12-01

Full Text Available In an overview and analytical study of the epidemiological data on the frequency of RET/РТС gene rearrangements in sporadic and radiogenic (patients after radiotherapy, residents of contaminated after the Chernobyl disaster areas, victims after the atomic bombings, etc. carcinomas of the thyroid gland were examined. In general, the observed epidemiological laws were confirmed in radiobiology experiments by irradiation of different cultures of thyroid cells and ex vivo with the exception of Chernobyl cohorts. Induction of RET/РТС gene rearrangements by 131l exposure in children carcinomas of Chernobyl residents in mice did not observe too. It is concluded that the situation with the frequency of RET/РТС rearrangements in thyroid carcinoma in Chernobyl cohorts once again confirms the multifactorial nature of the induction and development of these tumors with a contribution of radiation and non-radiation factors (iodine deficiency and different stresses.

Microdosimetric investigation of a fast neutron radiobiology facility utilising the d(4)-9Be reaction.

Science.gov (United States)

Waker, A J; Maughan, R L

1986-11-01

For fast neutron therapy and radiobiology beams, knowledge of the primary neutron spectrum is the most fundamental requirement for the definition of radiation quality. However, microdosimetric measurements in the form of single-event spectra not only complement the primary neutron spectrum as a statement of radiation quality but also provide a sensitive method of detecting changes in the radiation field in situations where it is no longer possible to have precise knowledge of the primary neutron spectrum, for example after collimator changes and in positions where the radiation field consists of a large scattered component. For the various collimator arrangements employed at the Gray Laboratory facility small perturbations of the radiation field are observed which can be related to a softening of the primary neutron spectrum with increasing field size of the collimator. Gamma fraction determinations are in very good agreement with measurements employing the dual chamber technique and also show small changes with collimator field size giving rise to gamma components ranging from 0.09 to 0.12, the higher values being measured for the larger field sizes. Quality changes represented by the shape of the measured event-size spectra and the derived microdosimetric parameters were greatest for off axis and phantom measurements. With increasing depth in water, yD was found to decrease from 47.3 keV micron-1 at 5 cm to 35.6 keV micron-1 at 15 cm depth, and the gamma fraction was found to increase from 0.23 to 0.40. Although there is no generally accepted and agreed method of relating microdosimetric information to biological effectiveness, the dual radiation theory in its original form (Kellerer and Rossi 1972) has been shown to be a very useful model for the assessment of the biological effectiveness of fast neutrons (Kellerer et al 1976). The microdosimetric parameter which is used in the dual radiation model is the dose mean specific energy corrected for saturation zeta

Radiobiological experiments in space: a review

International Nuclear Information System (INIS)

Horneck, G.

1992-01-01

This paper deals mainly with results from space experiments on the biological effects of cosmic ray high charge, high energy (HZE) particles and on their potential interactions with the microgravity environment. So far, mainly with resting systems, such as viruses, bacterial spores, plant seeds or shrimp cysts, as well as in a few embryonic systems, methods have been applied to trace injuries to the passage of a single HZE particle of comic radiation Most effects point to damage to the genetic material such as mutations, tumour induction, chromosomal aberrations, cell inactivation, or development anomalies. Using higher organisms, including mammals, a few attempts have been made to identify tissue damage along the passage of single HZE particles, such as microscopically visible injury in brain or eyes, or the light flash sensation. The latter, correlated with orbital parameters, showed highest frequency during the passage of the South Atlantic Anomaly. To study potential interactions of ionizing radiation with microgravity, either additional irradiation was applied, pre-, in-, or post-flight, or a 1 g reference centrifuge was utilized in combination with methods of particle effect correlation. Especially in embryonic systems, synergistic interactions were observed in producing mutations or anomalies with high frequency. It is assumed that, among other mechanisms, microgravity might interfere with the function of DNA repair systems. On the basis of the results obtained on the biological effectiveness of radiation in space and in view of upcoming space activities with an increasing number of manned missions, perspectives are given for future experimental approaches in space radiation biology. (author)

Impact of Radiogenic Heating on the Formation Conditions of Comet 67P/Churyumov–Gerasimenko

International Nuclear Information System (INIS)

Mousis, O.; Drouard, A.; Vernazza, P.; Le Deun, T.; Lunine, J. I.; Monnereau, M.; Rème, H.; Maggiolo, R.; Cessateur, G.; De Keyser, J.; Gasc, S.; Altwegg, K.; Balsiger, H.; Rubin, M.; Tzou, C.-Y.; Berthelier, J.-J.; Fuselier, S. A.; Korth, A.; Mall, U.; Marty, B.

2017-01-01

Because of the high fraction of refractory material present in comets, the heat produced by the radiogenic decay of elements such as aluminum and iron can be high enough to induce the loss of ultravolatile species such as nitrogen, argon, or carbon monoxide during their accretion phase in the protosolar nebula (PSN). Here, we investigate how heat generated by the radioactive decay of "2"6Al and "6"0Fe influences the formation of comet 67P/Churyumov–Gerasimenko, as a function of its accretion time and the size of its parent body. We use an existing thermal evolution model that includes various phase transitions, heat transfer in the ice-dust matrix, and gas diffusion throughout the porous material, based on thermodynamic parameters derived from Rosetta observations. Two possibilities are considered: either, to account for its bilobate shape, 67P/Churyumov–Gerasimenko was assembled from two primordial ∼2 km sized planetesimals, or it resulted from the disruption of a larger parent body with a size corresponding to that of comet Hale–Bopp (∼70 km). To fully preserve its volatile content, we find that either 67P/Churyumov–Gerasimenko’s formation was delayed between ∼2.2 and 7.7 Myr after that of Ca–Al-rich Inclusions in the PSN or the comet’s accretion phase took place over the entire time interval, depending on the primordial size of its parent body and the composition of the icy material considered. Our calculations suggest that the formation of 67P/Churyumov–Gerasimenko is consistent with both its accretion from primordial building blocks formed in the nebula or from debris issued from the disruption of a Hale–Bopp-like body.

Geochronology, radiogenic isotope geochemistry, and petrogenesis of Sang bast Paleo-tethys monzogranite, Mashhad, Iran

International Nuclear Information System (INIS)

Karimpour, M. H.; Farmer, G.L.; Stern, C.R.

2010-01-01

The study area is located in northeastern Iran (south of Mashhad). Paleo-Tethys Ocean opened during Silurian time and subduction under Turan plate was started in Late Devonian. By Late Triassic (225 Ma) there was no Paleo-Tethys left on an Iranian transect, therefore Turan plate obducted over Iran Plate. Two stages of low grade regional metamorphism are exposed, that are related to Hercynian (Late Paleozoic) and Cimmerian (Jurassic) oro genies. The Paleo-Tethys remnants (meta-ophiolite and meta-flysch) were intruded by Sang bast monzogranite. Chemically, monzogranite is moderately peraluminous S-type granitoid. It has low values of magnetic susceptibility [(5 to 11) * 10 -5 SI] therefore it is classified as belonging to the ilmenite-series of reduced type granitoids. Monzogranite is characterized by strong light rare earth element enrichment and less low heavy rare earth element. All samples have very small negative Eu anomalies (Eu/Eu * = 0.62 to 0.88). Total rare earth element content of monzogranite is between 212-481 ppm. The result of U-Pb zircon age dating of monzogranite is 201.3 ± 3.6 Ma (Upper Triassic, Rhaetian time). The initial 87 Sr/ 86 Sr and 143 Nd/ 144 Nd ratios for monzogranite is (0.706776 and 0.512219) when recalculated to an age of 201 Ma, consistent with the new radiometric. The initial 87 Sr/ 86 Sr and 143 Nd/ 144 Nd ratios for slate is (0.720613 and 0.511601) respectively when recalculated to an age of 201 Ma, consistent with the new radiometric results. Initial εNd isotope values for monzogranite is -3.13 and the slate is -15.19. Based on radiogenic isotopic data and rare earth element monzogranite magma originated either from lower continental crust which was very different from slate or it is originated from mantle and contaminated in continental crust during ascending.

Impact of Radiogenic Heating on the Formation Conditions of Comet 67P/Churyumov–Gerasimenko

Energy Technology Data Exchange (ETDEWEB)

Mousis, O.; Drouard, A.; Vernazza, P.; Le Deun, T. [Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France); Lunine, J. I. [Department of Astronomy and Carl Sagan Institute, Space Sciences Building Cornell University, Ithaca, NY 14853 (United States); Monnereau, M.; Rème, H. [Université de Toulouse, UPS-OMP-CNRS, IRAP, Toulouse (France); Maggiolo, R.; Cessateur, G.; De Keyser, J.; Gasc, S. [Royal Belgian Institute for Space Aeronomy, BIRA-IASB, Ringlaan 3, B-1180 Brussels (Belgium); Altwegg, K.; Balsiger, H.; Rubin, M.; Tzou, C.-Y. [Physikalisches Institut, University of Bern, Sidlerstr. 5, CH-3012 Bern (Switzerland); Berthelier, J.-J. [LATMOS/IPSL-CNRS-UPMC-UVSQ, 4 Avenue de Neptune F-94100, Saint-Maur (France); Fuselier, S. A. [Department of Space Science, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228 (United States); Korth, A.; Mall, U. [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Marty, B., E-mail: olivier.mousis@lam.fr [Centre de Recherches Pétrographiques et Géochimiques, CRPG-CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, F-54501 Vandoeuvre lès Nancy (France); and others

2017-04-10

Because of the high fraction of refractory material present in comets, the heat produced by the radiogenic decay of elements such as aluminum and iron can be high enough to induce the loss of ultravolatile species such as nitrogen, argon, or carbon monoxide during their accretion phase in the protosolar nebula (PSN). Here, we investigate how heat generated by the radioactive decay of {sup 26}Al and {sup 60}Fe influences the formation of comet 67P/Churyumov–Gerasimenko, as a function of its accretion time and the size of its parent body. We use an existing thermal evolution model that includes various phase transitions, heat transfer in the ice-dust matrix, and gas diffusion throughout the porous material, based on thermodynamic parameters derived from Rosetta observations. Two possibilities are considered: either, to account for its bilobate shape, 67P/Churyumov–Gerasimenko was assembled from two primordial ∼2 km sized planetesimals, or it resulted from the disruption of a larger parent body with a size corresponding to that of comet Hale–Bopp (∼70 km). To fully preserve its volatile content, we find that either 67P/Churyumov–Gerasimenko’s formation was delayed between ∼2.2 and 7.7 Myr after that of Ca–Al-rich Inclusions in the PSN or the comet’s accretion phase took place over the entire time interval, depending on the primordial size of its parent body and the composition of the icy material considered. Our calculations suggest that the formation of 67P/Churyumov–Gerasimenko is consistent with both its accretion from primordial building blocks formed in the nebula or from debris issued from the disruption of a Hale–Bopp-like body.

Skin carcinomas: Radiobiological principles, radiotherapeutic techniques and clinical management

International Nuclear Information System (INIS)

Schmidt-Ullrich, Rupert K.; Johnson, Christopher R.

1997-01-01

Purpose/Objective: The course will be divided into three major topics: (1) Review of radiobiological principles as they apply to the radiotherapeutic management of skin carcinomas; (2) review of radiotherapeutic techniques including beam qualities, beam collimation, tissue dose profiles, and the relative indications of external beam irradiation vs. brachytherapy; (3) comprehensive review of the tumor biology of skin malignancies, including malignant melanoma, and of the relative indications for radiotherapeutic and/or surgical management. (1) Review of critical data which have led to currently applied principles of time-dose-volume concepts in the radiotherapeutic management of skin carcinomas. Emphasis will be placed on the relative importance of fraction size and overall treatment time on tumor control probability and acute and late normal tissue toxicity. (2) Considering that radiotherapy in the management of skin carcinomas is often used to minimize patient disfiguration and to preserve critical body functions (e.g. eye lids) the technical aspects of radiotherapy delivery are most critical. Careful evaluation of the extent of the lesions including evaluation of their depth of invasion will determine the quality of the radiation beams, orthovoltage and low energy electrons being the most useful. Beam harding for orthovoltage beams and secondary and tertiary (skin) collimation of appropriate electron beams are critical. For more extensive and deeply invasive lesions contour-shaping through customized bolus material is essential. Equally important is the familiarity with custom shielding of critical structures, such as eyes, ears, oral cavity and central nervous system structures. Brachytherapy applications in the treatment of skin carcinomas is limited but should be considered when implants with high dose uniformity can be constructed. (3) The discussion of clinical management will start with a discussion of properties and routes of spread of the diverse

Skin carcinomas: radiobiological principles, radiotherapeutic techniques and clinical management

International Nuclear Information System (INIS)

Schmidt-Ullrich, Rupert K. A.; Johnson, Christopher R.

1995-01-01

Purpose/Objective: The course will be divided into three major topics: (1) Review of radiobiological principles as they apply to the radiotherapeutic management of skin carcinomas; (2) review of radiotherapeutic techniques including beam qualities, beam collimation, tissue dose profiles, and the relative indications of external beam irradiation vs. brachytherapy; (3) comprehensive review of the tumor biology of skin malignancies, including malignant melanoma, and of the relative indications for radiotherapeutic and/or surgical management. (1) Review of critical data which have lead to currently applied principles of time-dose-volume concepts in the radiotherapeutic management of skin carcinomas. Emphasis will be placed on the relative importance of fraction size and overall treatment time on tumor control probability and acute and late normal tissue toxicity. (2) Considering that radiotherapy in the management of skin carcinomas is often used to minimize patient disfiguration and to preserve critical body functions (e.g. eye lids) the technical aspects of radiotherapy delivery are most critical. Careful evaluation of the extent of the lesions including evaluation of their depth of invasion will determine the quality of the radiation beams, orthovoltage and low energy electrons being the most useful. Beam harding for orthovoltage beams and secondary and tertiary (skin) collimation of appropriate electron beams are critical. For more extensive and deeply invasive lesions contour-shaping through customized bolus material is essential. Equally important is the familiarity with custom shielding of critical structures, such as eyes, ears, oral cavity and central nervous system structures. Brachytherapy applications in the treatment of skin carcinomas is limited but should be considered when implants with high dose uniformity can be constructed. (3) The discussion of clinical management will start with a discussion of tumor biological properties of the diverse malignant

Radiobiological studies of cells in multicellular spheroids using a sequential trypsinization technique

International Nuclear Information System (INIS)

Giesbrecht, J.L.; Wilson, W.R.; Hill, R.P.

1981-01-01

The radiation response of V79 Chinese hamster cells grown as multicellular spheroids has been investigated by determining survival curves for treatment under a variety of different oxygen concentrations. Spheroids were irradiated under fully oxygenated conditions in air-equilibrated medium at 37 0 C, in medium exposed to lower oxygen tension (5% O 2 ) for times varying from 1 hr to 3 days, or under anoxic conditions. For comparison with the spheroids, using identical treatment conditions, V79 cells were grown in suspension as a subconfluent monolayer attached to Sephadex (microcarrier) beads and irradiated under fully oxygenated or anoxic conditions. The radiation response of cells at different depths within the spheroid was investigated by using a sequential trypsinization technique developed to remove eight or nine shells of cells successively from the spheroid surface. When irradiation was given under fully oxygenated conditions the outer few cell layers were more sensitive than the inner cells, a finding which is not understood. As expected the inner cells in spheroids irradiated in air (at 37 0 C) or in 5% O 2 are more resistant than the outer cells. For an acute exposure to 5% O 2 (1 hr) in the inner cells displayed full radiobiological hypoxia; however, for chronic exposures to low oxygen this was not the case. These results with the sequential trypsinization procedure suggest that the radiation response of cells in spheroids is more complex than anticipted

Tumor-Volume Simulation During Radiotherapy for Head-and-Neck Cancer Using a Four-Level Cell Population Model

International Nuclear Information System (INIS)

Chvetsov, Alexei V.; Dong Lei; Palta, Jantinder R.; Amdur, Robert J.

2009-01-01

Purpose: To develop a fast computational radiobiologic model for quantitative analysis of tumor volume during fractionated radiotherapy. The tumor-volume model can be useful for optimizing image-guidance protocols and four-dimensional treatment simulations in proton therapy that is highly sensitive to physiologic changes. Methods: The analysis is performed using two approximations: (1) tumor volume is a linear function of total cell number and (2) tumor-cell population is separated into four subpopulations: oxygenated viable cells, oxygenated lethally damaged cells, hypoxic viable cells, and hypoxic lethally damaged cells. An exponential decay model is used for disintegration and removal of oxygenated lethally damaged cells from the tumor. Results: We tested our model on daily volumetric imaging data available for 14 head-and-neck cancer patients treated with an integrated computed tomography/linear accelerator system. A simulation based on the averaged values of radiobiologic parameters was able to describe eight cases during the entire treatment and four cases partially (50% of treatment time) with a maximum 20% error. The largest discrepancies between the model and clinical data were obtained for small tumors, which may be explained by larger errors in the manual tumor volume delineation procedure. Conclusions: Our results indicate that the change in gross tumor volume for head-and-neck cancer can be adequately described by a relatively simple radiobiologic model. In future research, we propose to study the variation of model parameters by fitting to clinical data for a cohort of patients with head-and-neck cancer and other tumors. The potential impact of other processes, like concurrent chemotherapy, on tumor volume should be evaluated.

Hypo-fractionated treatment in radiotherapy: radio-biological models Tcp and NTCP; Tratamiento hipofraccionado en radioterapia: modelos radiobiologicos TCP y NTCP

Energy Technology Data Exchange (ETDEWEB)

Astudillo V, A. J.; Mitsoura, E. [Universidad Autonoma del Estado de Mexico, Facultad de Medicina, Paseo Tollocan s/n, 50180 Toluca, Estado de Mexico (Mexico); Paredes G, L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Resendiz G, G., E-mail: lydia.paredes@inin.gob.mx [Hospital Medica Sur, Departamento de Radioterapia, Puente de Piedra 150, Col. Toriello Guerra, 14050 Mexico D. F. (Mexico)

2014-08-15

At the present time the breast cancer in Mexico has the first place of incidence of the malignant neoplasia s in the women, and represents 11.34% of all the cancer cases. On the other hand, the treatments for cancer by means of ionizing radiations have been dominated under the approaches of the medical radio-oncologists which have been based on test and error by many years. The radio-biological models, as the Tcp, NTCP and dosimetric variables, for their clinical application in the conventional radiotherapy with hypo-fractionation have as purpose predicting personalized treatment plans that they present most probability of tumor control and minor probability of late reactions, becoming this way support tools in the decisions taking for the patient treatments planning of Medical Physicists and Radio-oncologists. (Author)

SU-F-T-545: Dosimetric and Radiobiological Evaluation of Dose Calculation Algorithms On Prostate Stereotactic Body Radiotherapy Using Conventional Flattened and Flattening-Filter-Free Beam

International Nuclear Information System (INIS)

Kang, S; Suh, T; Chung, J; Eom, K; Lee, J

2016-01-01

Purpose: The purpose of this study is to evaluate the dosimetric and radiobiological impact of Acuros XB (AXB) and Anisotropic Analytic Algorithm (AAA) dose calculation algorithms on prostate stereotactic body radiation therapy plans with both conventional flattened (FF) and flattening-filter free (FFF) modes. Methods: For thirteen patients with prostate cancer, SBRT planning was performed using 10-MV photon beam with FF and FFF modes. The total dose prescribed to the PTV was 42.7 Gy in 7 fractions. All plans were initially calculated using AAA algorithm in Eclipse treatment planning system (11.0.34), and then were re-calculated using AXB with the same MUs and MLC files. The four types of plans for different algorithms and beam energies were compared in terms of homogeneity and conformity. To evaluate the radiobiological impact, the tumor control probability (TCP) and normal tissue complication probability (NTCP) calculations were performed. Results: For PTV, both calculation algorithms and beam modes lead to comparable homogeneity and conformity. However, the averaged TCP values in AXB plans were always lower than in AAA plans with an average difference of 5.3% and 6.1% for 10-MV FFF and FF beam, respectively. In addition, the averaged NTCP values for organs at risk (OARs) were comparable. Conclusion: This study showed that prostate SBRT plan were comparable dosimetric results with different dose calculation algorithms as well as delivery beam modes. For biological results, even though NTCP values for both calculation algorithms and beam modes were similar, AXB plans produced slightly lower TCP compared to the AAA plans.

SU-F-T-545: Dosimetric and Radiobiological Evaluation of Dose Calculation Algorithms On Prostate Stereotactic Body Radiotherapy Using Conventional Flattened and Flattening-Filter-Free Beam

Energy Technology Data Exchange (ETDEWEB)

Kang, S; Suh, T [The catholic university of Korea, Seoul (Korea, Republic of); Chung, J; Eom, K [Seoul National University Bundang Hospital (Korea, Republic of); Lee, J [Konkuk University Medical Center (Korea, Republic of)

2016-06-15

Purpose: The purpose of this study is to evaluate the dosimetric and radiobiological impact of Acuros XB (AXB) and Anisotropic Analytic Algorithm (AAA) dose calculation algorithms on prostate stereotactic body radiation therapy plans with both conventional flattened (FF) and flattening-filter free (FFF) modes. Methods: For thirteen patients with prostate cancer, SBRT planning was performed using 10-MV photon beam with FF and FFF modes. The total dose prescribed to the PTV was 42.7 Gy in 7 fractions. All plans were initially calculated using AAA algorithm in Eclipse treatment planning system (11.0.34), and then were re-calculated using AXB with the same MUs and MLC files. The four types of plans for different algorithms and beam energies were compared in terms of homogeneity and conformity. To evaluate the radiobiological impact, the tumor control probability (TCP) and normal tissue complication probability (NTCP) calculations were performed. Results: For PTV, both calculation algorithms and beam modes lead to comparable homogeneity and conformity. However, the averaged TCP values in AXB plans were always lower than in AAA plans with an average difference of 5.3% and 6.1% for 10-MV FFF and FF beam, respectively. In addition, the averaged NTCP values for organs at risk (OARs) were comparable. Conclusion: This study showed that prostate SBRT plan were comparable dosimetric results with different dose calculation algorithms as well as delivery beam modes. For biological results, even though NTCP values for both calculation algorithms and beam modes were similar, AXB plans produced slightly lower TCP compared to the AAA plans.

Radiobiological significance of radioactive contamination - summary assessment based on great number of measurements

International Nuclear Information System (INIS)

Angelov, V.; Bonchev, Ts.; Mavrodiev, V.; Kyrdzhilov, N.

1995-01-01

In order to facilitate quantitative and qualitative characterisation of radioactive contamination the authors introduce a relative estimate of radionuclide activity by setting as a reference the most abundant element -Co-60 in the case of the Kozloduy NPP. The ratio η i of the mean annual permissible concentration in air for each radionuclide (RPC-92) to that of Co-60 is calculated. It is found that η i has the same or close values for groups of radionuclides, e.g. η i = 2.10 -4 for 238 Pu, 239 Pu, 240 Pu, 241 Am, 244 Cm; η i = 5 for 89 Sr, 91 Y; 93 Nb, 134 Cs, 137 Cs; η i = 50 for 55 Fe, 63 Ni, 95 Zr, 95 Nb, 140 Ba, 140 La. Then it is compared to the experimentally measured values of the same quantity η iexp , derived from surface contamination data. The ratio η iexp /η i is plotted against log η i . The resulting nomograms give graphic representation of the radiobiological significance of various radionuclide groups. Data from different locations at the Kozloduy NPP are presented. It is found that the alpha emitter contamination has highest values in the Unit 1 (WWER-440) control rooms after repair. The Unit 5 (WWER-1000) has lower alpha contamination compared to WWER-440 units. 1 ref., 5 figs., 1 tab

Analysis of the radiobiology of ytterbium-169 and iodine-125 permanent brachytherapy implants

Energy Technology Data Exchange (ETDEWEB)

Lazarescu, G.R. [Windsor Regional Cancer Center, Ontario Cancer Treatment and Research Foundation, Windsor, Canada N8W 2X3 (Canada); Battista, J.J. [London Regional Cancer Center, Ontario Cancer Treatment and Research Foundation, Dept. of Oncology and Dept. of Medical Biophysics, University of Western Ontario, London, Canada N6A 4L6 (Canada)

1997-09-01

Recently, Yb-169 has been considered as a potential replacement for I-125 and Pd-103 in permanent implants. In spite of the uncertainties in the parameters necessary for an accurate radiobiological modelling, the linear quadratic model can be useful in the comparative evaluation of the radiotherapeutic merit of similar implants. In order to find out if a Yb-169 permanent implant can be made biologically 'equivalent' to an I-125 implant, we studied the dependence of local control on the tumour cell radiosensitivity and on the balance between the rate of tumour cell killing and tumour cell proliferation, for rapidly and slowly proliferating tumours. The extrapolated response dose (ERD) has been calculated for tumour and late reacting normal tissue for both types of implants and the possible biological restrictions due to the normal tissue tolerance have been discussed. Our theoretical analysis is consistent with the clinical results published for I-125 permanent implants in prostate tumours and meningiomas. It predicts that Yb-169, which has only recently been used in human tumours, can provide comparable tumour control for permanent implants in slowly proliferating tumours with an initial dose rate of 13 cGy h{sup -1}. Control might be extended to rapidly proliferating tumours by increasing the initial dose rate within a range consistent with an acceptable level of normal tissue late reaction. (author)

Radiobiological experiments with heavy ions: a comparison of the cross sections of different biological endpoints

International Nuclear Information System (INIS)

Kraft, G.

1989-01-01

Biological effect of heavy charged particles was studied in experiment at the Unilac on different physical, chemical and biological levels. On these experiments a large body of radiobiological data, cross sections for cell inactivation and mutation, induction of both, chromosome aberrations, and strand breaks, of DNA have been measured for different atomic numbers, from helium (z=2) to uranium (z=92), and at an LET range from 10 to 16000 keV/μm. At LET values below 100 keV/μm all data points to one specific effect form one single curve as a function of LET, independent of the atomic number of the ion. In this LET range the biological effects are independent of the particle energy or track structure and depend only on the energy transfer. Therefore LET is a good parameter in this regime. For LET values greater than 100 keV/μm this regime LET is no longer a good parameter and the physical parameters of the formation of particle track are important. The energy and angular distribution of the electrons in a solid target has to be measured. 28 refs.; 14 figs

Radiobiology of Small Hive Beetle (Coleoptera: Nitidulidae) and Prospects for Management Using Sterile Insect

International Nuclear Information System (INIS)

Downey, Danielle; Chun, Stacey; Follett, Peter

2016-01-01

Small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), is considered a serious threat to beekeeping in the Western Hemisphere, Australia, and Europe mainly due to larval feeding on honey, pollen, and brood of the European honeybee, Apis mellifera L. Control methods are limited for this pest. Studies were conducted to provide information on the radiobiology of small hive beetle and determine the potential for sterile insect releases as a control strategy. Adult males and females were equally sensitive to a radiation dose of 80 Gy and died within 5–7 d after treatment. In reciprocal crossing studies, irradiation of females only lowered reproduction to a greater extent than irradiation of males only. For matings between unirradiated males and irradiated females, mean reproduction was reduced by >99% at 45 and 60 Gy compared with controls, and no larvae were produced at 75 Gy. Irradiation of prereproductive adults of both sexes at 45 Gy under low oxygen (1–4%) caused a high level of sterility (>99%) while maintaining moderate survivorship for several weeks, and should suffice for sterile insect releases. Sterile insect technique holds potential for suppressing small hive beetle populations in newly invaded areas and limiting its spread. (author)

Radiobiological effectiveness of high LET radiation

Energy Technology Data Exchange (ETDEWEB)

Urano, M; Koike, S; Suzuki, Y; Todoroki, T [National Inst. of Radiological Sciences, Chiba (Japan)

1977-03-01

The effect of cyclotron-produced neutrons (30 MeV d ..-->.. Be) on an animal tumors was studied. The experimental tumors were 5th generation isotransplants of spontaneous mouse squamous cell carcinoma. C3Hf/He mouse were used throughout. Cell survival was examined by the TD/sub 50/ method after neutron or x-ray irradiation. Tumor regrowth was also analysed by measuring tumor size daily. Results indicated that RBE was higher at low dose level, tumor cells surviving a neutron dose were not capable of repairing potentially lethal damage, and the OER was less after neutrons than after x rays. Implications of these results in radiation oncology and therapy were discussed.

Novel pattern of post-γ ray de novo DNA synthesis in a radioresistant human strain

International Nuclear Information System (INIS)

Mirzayans, R.; Gentner, N.E.; Paterson, M.C.

1985-01-01

Enhanced resistance to radiation cytotoxicity in a fibroblast strain from an afflicted member of a Li-Fraumeni syndrome family may be largely ascribable to a change in the pattern of DNA replicative synthesis following γ ray exposure. That is, the extent of the initial radiogenic inhibition of replicative synthesis and the time interval before its subsequent recovery were both found to be greater in radioresistant (RR) compared to normal cells. In addition, the post-recovery replication rates in the RR cells were both higher and longer lasting than those in the control cells. A similar differential pattern was also seen following treatment with 4NQO, another DNA-damaging agent to which this RR strain displays enhanced resistance. Moreover, several conventional DNA repair assays indicated that the RR cells repair radiogenic damage at normal rates. The authors therefore suggest that the increased inhibition and prolonged lag in resumption of replicative synthesis seen in the RR strain upon exposure to certain genotoxic agents may enhance cellular recovery by ''buying additional time'' for processing of potentially lethal lesions

Incremental heating of Bishop Tuff sanidine reveals preeruptive radiogenic Ar and rapid remobilization from cold storage

Science.gov (United States)

Andersen, Nathan L.; Jicha, Brian R.; Singer, Brad S.; Hildreth, Wes

2017-11-01

Accurate and precise ages of large silicic eruptions are critical to calibrating the geologic timescale and gauging the tempo of changes in climate, biologic evolution, and magmatic processes throughout Earth history. The conventional approach to dating these eruptive products using the 40Ar/39Ar method is to fuse dozens of individual feldspar crystals. However, dispersion of fusion dates is common and interpretation is complicated by increasingly precise data obtained via multicollector mass spectrometry. Incremental heating of 49 individual Bishop Tuff (BT) sanidine crystals produces 40Ar/39Ar dates with reduced dispersion, yet we find a 16-ky range of plateau dates that is not attributable to excess Ar. We interpret this dispersion to reflect cooling of the magma reservoir margins below ˜475 °C, accumulation of radiogenic Ar, and rapid preeruption remobilization. Accordingly, these data elucidate the recycling of subsolidus material into voluminous rhyolite magma reservoirs and the effect of preeruptive magmatic processes on the 40Ar/39Ar system. The youngest sanidine dates, likely the most representative of the BT eruption age, yield a weighted mean of 764.8 ± 0.3/0.6 ka (2σ analytical/full uncertainty) indicating eruption only ˜7 ky following the Matuyama‑Brunhes magnetic polarity reversal. Single-crystal incremental heating provides leverage with which to interpret complex populations of 40Ar/39Ar sanidine and U-Pb zircon dates and a substantially improved capability to resolve the timing and causal relationship of events in the geologic record.

Radiobiological impact of dose calculation algorithms on biologically optimized IMRT lung stereotactic body radiation therapy plans

International Nuclear Information System (INIS)

Liang, X.; Penagaricano, J.; Zheng, D.; Morrill, S.; Zhang, X.; Corry, P.; Griffin, R. J.; Han, E. Y.; Hardee, M.; Ratanatharathom, V.

2016-01-01

The aim of this study is to evaluate the radiobiological impact of Acuros XB (AXB) vs. Anisotropic Analytic Algorithm (AAA) dose calculation algorithms in combined dose-volume and biological optimized IMRT plans of SBRT treatments for non-small-cell lung cancer (NSCLC) patients. Twenty eight patients with NSCLC previously treated SBRT were re-planned using Varian Eclipse (V11) with combined dose-volume and biological optimization IMRT sliding window technique. The total dose prescribed to the PTV was 60 Gy with 12 Gy per fraction. The plans were initially optimized using AAA algorithm, and then were recomputed using AXB using the same MUs and MLC files to compare with the dose distribution of the original plans and assess the radiobiological as well as dosimetric impact of the two different dose algorithms. The Poisson Linear-Quadatric (PLQ) and Lyman-Kutcher-Burman (LKB) models were used for estimating the tumor control probability (TCP) and normal tissue complication probability (NTCP), respectively. The influence of the model parameter uncertainties on the TCP differences and the NTCP differences between AAA and AXB plans were studied by applying different sets of published model parameters. Patients were grouped into peripheral and centrally-located tumors to evaluate the impact of tumor location. PTV dose was lower in the re-calculated AXB plans, as compared to AAA plans. The median differences of PTV(D 95% ) were 1.7 Gy (range: 0.3, 6.5 Gy) and 1.0 Gy (range: 0.6, 4.4 Gy) for peripheral tumors and centrally-located tumors, respectively. The median differences of PTV(mean) were 0.4 Gy (range: 0.0, 1.9 Gy) and 0.9 Gy (range: 0.0, 4.3 Gy) for peripheral tumors and centrally-located tumors, respectively. TCP was also found lower in AXB-recalculated plans compared with the AAA plans. The median (range) of the TCP differences for 30 month local control were 1.6 % (0.3 %, 5.8 %) for peripheral tumors and 1.3 % (0.5 %, 3.4 %) for centrally located tumors. The lower

WE-AB-202-11: Radiobiological Modeling of Tumor Response During Radiotherapy Based On Pre-Treatment Dynamic PET Imaging Data

Energy Technology Data Exchange (ETDEWEB)

Crispin-Ortuzar, M; Grkovski, M; Beattie, B; Lee, N; Riaz, N; Humm, J; Jeong, J; Fontanella, A; Deasy, J [Memorial Sloan Kettering Cancer Center, New York, NY (United States)

2016-06-15

Purpose: To evaluate the ability of a multiscale radiobiological model of tumor response to predict mid-treatment hypoxia images, based on pretreatment imaging of perfusion and hypoxia with [18-F]FMISO dynamic PET and glucose metabolism with [18-F]FDG PET. Methods: A mechanistic tumor control probability (TCP) radiobiological model describing the interplay between tumor cell proliferation and hypoxia (Jeong et al., PMB 2013) was extended to account for intra-tumor nutrient heterogeneity, dynamic cell migration due to nutrient gradients, and stromal cells. This extended model was tested on 10 head and neck cancer patients treated with chemoradiotherapy, randomly drawn from a larger MSKCC protocol involving baseline and mid-therapy dynamic PET scans. For each voxel, initial fractions of proliferative and hypoxic tumor cells were obtained by finding an approximate solution to a system of linear equations relating cell fractions to voxel-level FDG uptake, perfusion (FMISO K{sub 1}) and hypoxia (FMISO k{sub 3}). The TCP model then predicted their evolution over time up until the mid treatment scan. Finally, the linear model was reapplied to predict each lesion’s median hypoxia level (k{sub 3}[med,sim]) which in turn was compared to the FMISO k{sub 3}[med] measured at mid-therapy. Results: The average k3[med] of the tumors in pre-treatment scans was 0.0035 min{sup −1}, with an inter-tumor standard deviation of σ[pre]=0.0034 min{sup −1}. The initial simulated k{sub 3}[med,sim] of each tumor agreed with the corresponding measurements within 0.1σ[pre]. In 7 out of 10 lesions, the mid-treatment k{sub 3}[med,sim] prediction agreed with the data within 0.3σ[pre]. The remaining cases corresponded to the most extreme relative changes in k{sub 3}[med]. Conclusion: This work presents a method to personalize the prediction of a TCP model using pre-treatment kinetic imaging data, and validates the modeling of radiotherapy response by predicting changes in median hypoxia

Damage analysis: damage function development and application

International Nuclear Information System (INIS)

Simons, R.L.; Odette, G.R.

1975-01-01

The derivation and application of damage functions, including recent developments for the U.S. LMFBR and CTR programs, is reviewed. A primary application of damage functions is in predicting component life expectancies; i.e., the fluence required in a service spectrum to attain a specified design property change. An important part of the analysis is the estimation of the uncertainty in such fluence limit predictions. The status of standardizing the procedures for the derivation and application of damage functions is discussed. Improvements in several areas of damage function development are needed before standardization can be completed. These include increasing the quantity and quality of the data used in the analysis, determining the limitations of the analysis due to the presence of multiple damage mechanisms, and finally, testing of damage function predictions against data obtained from material surveillance programs in operating thermal and fast reactors. 23 references. (auth)

Mammalian cell biology

International Nuclear Information System (INIS)

Elkind, M.M.

1975-01-01

Progress is reported on the following research projects: the effects of N-ethyl-maleimide and hydroxyurea on hamster cells in culture; sensitization of synchronized human cells to x rays by N-ethylmaleimide; sensitization of hypoxic mammalian cells with a sulfhydryl inhibitor; damage interaction due to ionizing and nonionizing radiation in mammalian cells; DNA damage relative to radioinduced cell killing; spurious photolability of DNA labeled with methyl- 14 C-thymidine; radioinduced malignant transformation of cultured mouse cells; a comparison of properties of uv and near uv light relative to cell function and DNA damage; Monte Carlo simulation of DNA damage and repair mechanisms; and radiobiology of fast neutrons

Physics and radiobiology of heavy charged particles in relation to the use of ion beams for therapy

International Nuclear Information System (INIS)

Kraft, G.; Haberer, T.; Schardt, D.; Scholz, M.

1993-07-01

Heavy charged particles are the most advanced tool of an external subcutane radiotherapy of deep seated tumors. Small angular- and lateral-scattering and the increase of the energy deposition with penetration depth are the physical basis for a more efficient tumor targeting. High biological efficiency in the tumor is the prerequisite for a successful treatment of tumors radioresistant against sparsely ionizing radiation. The possibility to perform target conform irradiation and to control the achieved/actual distribution using PET techniques guarantees that biological highly efficient stepping particles can be restricted to the tumor volume only. Although the physical and radiobiological properties of ion beams are very favourable for therapy, the necessity to produce these particles in an accelerator restricts a general application of heavy ions up to now. Presently the heavy ion accelerator SIS at GSI is the only source of heavy ion beams, sufficient in energy and intensity for therapy. A therapy unit is in preparation at GSI, the status of this project is given at the end of the paper. (orig.)

Research projects in radiobiology and radiation protection

International Nuclear Information System (INIS)

1960-01-01

Of the research projects sponsored by the International Atomic Energy Agency quite a large number are concerned with the biological effects of ionizing radiation. That itself, of course, is a very wide field covering such subjects as the nature and mechanism of radiation damage, genetic mutations, the varying radiosensitivity of different organisms, ways of modifying the natural sensitivity or resistance, and biological and chemical means of protection. In all these branches of enquiry, the Agency has awarded research contracts to scientific institutes or laboratories in different countries

Research projects in radiobiology and radiation protection

Energy Technology Data Exchange (ETDEWEB)

NONE

1960-04-15

Of the research projects sponsored by the International Atomic Energy Agency quite a large number are concerned with the biological effects of ionizing radiation. That itself, of course, is a very wide field covering such subjects as the nature and mechanism of radiation damage, genetic mutations, the varying radiosensitivity of different organisms, ways of modifying the natural sensitivity or resistance, and biological and chemical means of protection. In all these branches of enquiry, the Agency has awarded research contracts to scientific institutes or laboratories in different countries

Heat flow and radiogenic heat production in Brazil with implications for thermal evolution of continents

International Nuclear Information System (INIS)

Vitorello, I.

1978-01-01

Heat flow and heat production results are reported from nineteen widely spaced sites in eastern and central parts of Brazil. Three sites in the stable Sao Francisco Craton comprising rocks with Transamazonic ages (2600 to 1800 Ma) or older present an average heat flow of 41.8 +- 4.6 (standard error of the mean=sem) mW m -2 , typical of shield areas; eight sites located in the Late Precambrian Braziliane metamorphic belt have an average heat flow of 54.7 +- 3.8 (sem) mW m -2 ; and four sites in the Parana basin, locus of a Late Jurassic-Early Cretaceous basaltic volcanicity, have a mean heat flow of 70.1 +- 5.9 (sem) mW m -2 . Heat flow results from the Late Cretaceous-Early Tertiary alkalic intrusion of Pocos de Caldas have yielded a site mean of 55.3 mW m -2 . These results indicate a systematic decrease of heat flow with increasing age of the last tectonothermal event. As an explanation for this pattern, a model comprising three main heat flow components is advanced: radiogenic heat from the crust (40%), with the decrease of this contribution with time being achieved by erosional removal of radioactive material; a residual heat from a transient thermal perturbation associated with tectogenesis; and a uniform heat flow of about 28 mW m -2 from deeper sources. The Coastal Brazilian Shield is characterized by ordinary surface and reduced heat flow, but its heat production appears to be less concentrated near the surface, and distributed over a greater depth. Because of the variation in plate thickness, relative movements between the South American plate and the underlying mantle material are possibly constrained to depths exceeding 400 km

Predicted risks of radiogenic cardiac toxicity in two pediatric patients undergoing photon or proton radiotherapy

International Nuclear Information System (INIS)

Zhang, Rui; Howell, Rebecca M; Homann, Kenneth; Giebeler, Annelise; Taddei, Phillip J; Mahajan, Anita; Newhauser, Wayne D

2013-01-01

Hodgkin disease (HD) and medulloblastoma (MB) are common malignancies found in children and young adults, and radiotherapy is part of the standard treatment. It was reported that these patients who received radiation therapy have an increased risk of cardiovascular late effects. We compared the predicted risk of developing radiogenic cardiac toxicity after photon versus proton radiotherapies for a pediatric patient with HD and a pediatric patient with MB. In the treatment plans, each patient’s heart was contoured in fine detail, including substructures of the pericardium and myocardium. Risk calculations took into account both therapeutic and stray radiation doses. We calculated the relative risk (RR) of cardiac toxicity using a linear risk model and the normal tissue complication probability (NTCP) values using relative seriality and Lyman models. Uncertainty analyses were also performed. The RR values of cardiac toxicity for the HD patient were 7.27 (proton) and 8.37 (photon), respectively; the RR values for the MB patient were 1.28 (proton) and 8.39 (photon), respectively. The predicted NTCP values for the HD patient were 2.17% (proton) and 2.67% (photon) for the myocardium, and were 2.11% (proton) and 1.92% (photon) for the whole heart. The predicted ratios of NTCP values (proton/photon) for the MB patient were much less than unity. Uncertainty analyses revealed that the predicted ratio of risk between proton and photon therapies was sensitive to uncertainties in the NTCP model parameters and the mean radiation weighting factor for neutrons, but was not sensitive to heart structure contours. The qualitative findings of the study were not sensitive to uncertainties in these factors. We conclude that proton and photon radiotherapies confer similar predicted risks of cardiac toxicity for the HD patient in this study, and that proton therapy reduced the predicted risk for the MB patient in this study