These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Radiation dosimetry.  

PubMed Central

This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists. PMID:2040250

Cameron, J

1991-01-01

2

Effect of respiratory motion on internal radiation dosimetry  

SciTech Connect

Purpose: Estimation of the radiation dose to internal organs is essential for the assessment of radiation risks and benefits to patients undergoing diagnostic and therapeutic nuclear medicine procedures including PET. Respiratory motion induces notable internal organ displacement, which influences the absorbed dose for external exposure to radiation. However, to their knowledge, the effect of respiratory motion on internal radiation dosimetry has never been reported before. Methods: Thirteen computational models representing the adult male at different respiratory phases corresponding to the normal respiratory cycle were generated from the 4D dynamic XCAT phantom. Monte Carlo calculations were performed using the MCNP transport code to estimate the specific absorbed fractions (SAFs) of monoenergetic photons/electrons, the S-values of common positron-emitting radionuclides (C-11, N-13, O-15, F-18, Cu-64, Ga-68, Rb-82, Y-86, and I-124), and the absorbed dose of {sup 18}F-fluorodeoxyglucose ({sup 18}F-FDG) in 28 target regions for both the static (average of dynamic frames) and dynamic phantoms. Results: The self-absorbed dose for most organs/tissues is only slightly influenced by respiratory motion. However, for the lung, the self-absorbed SAF is about 11.5% higher at the peak exhale phase than the peak inhale phase for photon energies above 50 keV. The cross-absorbed dose is obviously affected by respiratory motion for many combinations of source-target pairs. The cross-absorbed S-values for the heart contents irradiating the lung are about 7.5% higher in the peak exhale phase than the peak inhale phase for different positron-emitting radionuclides. For {sup 18}F-FDG, organ absorbed doses are less influenced by respiratory motion. Conclusions: Respiration-induced volume variations of the lungs and the repositioning of internal organs affect the self-absorbed dose of the lungs and cross-absorbed dose between organs in internal radiation dosimetry. The dynamic anatomical model provides more accurate internal radiation dosimetry estimates for the lungs and abdominal organs based on realistic modeling of respiratory motion. This work also contributes to a better understanding of model-induced uncertainties in internal radiation dosimetry.

Xie, Tianwu [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva 4 CH-1211 (Switzerland); Zaidi, Habib, E-mail: habib.zaidi@hcuge.ch [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva 4 CH-1211 (Switzerland); Geneva Neuroscience Center, Geneva University, Geneva CH-1205 (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen 9700 RB (Netherlands)

2014-11-01

3

Standard Practice for Dosimetry of Proton Beams for use in Radiation Effects Testing of Electronics  

Microsoft Academic Search

Representatives of facilities that routinely deliver protons for radiation effect testing are collaborating to establish a set of standard best practices for proton dosimetry. These best practices will be submitted to the ASTM International for adoption.

Margaret A. McMahan; Ewart Blackmore; Ethan W. Cascio; Carlos Castaneda; Barbara von Przewoski; Harvey Eisen

2008-01-01

4

Standard Practice for Dosimetry of Proton Beams for use in Radiation Effects Testing of Electronics  

SciTech Connect

Representatives of facilities that routinely deliver protons for radiation effect testing are collaborating to establish a set of standard best practices for proton dosimetry. These best practices will be submitted to the ASTM International for adoption.

McMahan, Margaret A.; Blackmore, Ewart; Cascio, Ethan W.; Castaneda, Carlos; von Przewoski, Barbara; Eisen, Harvey

2008-07-25

5

The dosimetry of ionizing radiation. Volume 1  

SciTech Connect

This book discusses the papers on dosimetry of ionizing radiation. The topics covered are: theoretical basis for dosimetry; fundamentals of microdosimetry; dosimetry of external radiation beams of photon and electron radiation; beam characteristics dosimetry of nuclear particles; measurement and dosimetry of radioactivity in the environment; and internal dosimetry for radiation protection.

Kase, K.R.; Bjarngard, B.E.; Attix, F.H.

1985-01-01

6

Fundamentals of Radiation Dosimetry  

SciTech Connect

The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

Bos, Adrie J. J. [Delft University of Technology, Faculty of Applied Sciences, Mekelweg 15, 2629JB Delft (Netherlands)

2011-05-05

7

Dosimetry for quantitative analysis of low dose ionizing radiation effects on humans in radiation therapy patients  

SciTech Connect

We have successfully developed a practical approach to predicting the location of skin surface dose at potential biopsy sites that receive 1 cGy and 10 cGy, respectively, in support of in vivo biologic dosimetry in humans. This represents a significant technical challenge as the sites lie on the patient surface out side the radiation fields. The PEREGRINE Monte Carlo simulation system was used to model radiation dose delivery and TLDs were used for validation on a phantom and confirmation during patient treatment. In the developmental studies the Monte Carlo simulations consistently underestimated the dose at the biopsy site by approximately 15% for a realistic treatment configuration, most likely due to lack of detail in the simulation of the linear accelerator outside the main beam line. Using a single, thickness-independent correction factor for the clinical calculations, the average of 36 measurements for the predicted 1 cGy point was 0.985 cGy (standard deviation: 0.110 cGy) despite patient breathing motion and other real world challenges. Since the 10 cGy point is situated in the region of high dose gradient at the edge of the field, patient motion had a greater effect and the six measured points averaged 5.90 cGy (standard deviation: 1.01 cGy), a difference that is equivalent to approximately a 6 mm shift on the patient's surface.

Lehmann, J; Stern, R L; Daly, T P; Schwieter, C W; Jones, G E; Arnold, M L; Hartmann-Siantar, C L; Goldberg, Z

2004-04-20

8

2015 Radiation Epidemiology and Dosimetry Course  

Cancer.gov

Mark your calendars for the 2015 Radiation Epidemiology and Dosimetry Course, offered by the Radiation Epidemiology Branch, part of NCI's Division of Cancer Epidemiology and Genetics (DCEG). World renowned radiation experts will discuss basic principles and the most up-to-date thinking about the health effects of radiation exposure.

9

Radiation effects on MOS devices - dosimetry, annealing, irradiation sequence, and sources  

NASA Technical Reports Server (NTRS)

This paper reports on some investigations of dosimetry, annealing, irradiation sequences, and radioactive sources, involved in the determination of radiation effects on MOS devices. Results show that agreement in the experimental and theoretical surface to average doses support the use of thermo-luminescent dosimeters (manganese activated calcium fluoride) in specifying the surface dose delivered to thin gate insulators of MOS devices. Annealing measurements indicate the existence of at least two energy levels,,s or a activation energies, for recovery of soft oxide MOS devices after irradiation by electrons, protons, and gammas. Damage sensitivities of MOS devices were found to be independent of combinations and sequences of radiation type or energies. Comparison of various gamma sources indicated a small dependence of damage sensitivity on the Cobalt facility, but a more significant dependence in the case of the Cesium source. These results were attributed to differences in the spectral content of the several sources.

Stassinopoulos, E. G.; Brucker, G. J.; Van Gunten, O.; Knudson, A. R.; Jordan, T. M.

1983-01-01

10

Analysis of MIR-18 results for physical and biological dosimetry: radiation shielding effectiveness in LEO  

NASA Technical Reports Server (NTRS)

We compare models of radiation transport and biological response to physical and biological dosimetry results from astronauts on the Mir space station. Transport models are shown to be in good agreement with physical measurements and indicate that the ratio of equivalent dose from the Galactic Cosmic Rays (GCR) to protons is about 3/2:1 and that this ratio will increase for exposures to internal organs. Two biological response models are used to compare to the Mir biodosimetry for chromosome aberration in lymphocyte cells; a track-structure model and the linear-quadratic model with linear energy transfer (LET) dependent weighting coefficients. These models are fit to in vitro data for aberration formation in human lymphocytes by photons and charged particles. Both models are found to be in reasonable agreement with data for aberrations in lymphocytes of Mir crew members: however there are differences between the use of LET dependent weighting factors and track structure models for assigning radiation quality factors. The major difference in the models is the increased effectiveness predicted by the track model for low charge and energy ions with LET near 10 keV/micrometers. The results of our calculations indicate that aluminum shielding, although providing important mitigation of the effects of trapped radiation, provides no protective effect from the galactic cosmic rays (GCR) in low-earth orbit (LEO) using either equivalent dose or the number of chromosome aberrations as a measure until about 100 g/cm 2 of material is used.

Cucinotta, F. A.; Wilson, J. W.; Williams, J. R.; Dicello, J. F.

2000-01-01

11

Introduction to Radiological Physics and Radiation Dosimetry  

Microsoft Academic Search

A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as photographic, calorimetric, chemical, and thermoluminescence dosimetry. Includes many new derivations, such as Kramers X-ray spectrum, as well as topics that

Frank Herbert Attix

1987-01-01

12

Remote radiation dosimetry  

DOEpatents

Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via transmissive fiber which also preferably serves to return the emission from the luminescent sensor. The stimulating beam is advantageously split by a beam splitter to create a detector beam which is measured for power during a reading period during which the luminescent phosphor is read. The detected power is preferably used to control the beam generator to thus produce desired beam power during the reading period. The luminescent emission from the remote sensor is communicated to a suitable emission detector, preferably after filtering or other selective treatment to better isolate the luminescent emission.

Braunlich, Peter F. (Pullman, WA); Tetzlaff, Wolfgang (Pullman, WA); Hegland, Joel E. (Pullman, WA); Jones, Scott C. (Pullman, WA)

1991-01-01

13

Remote radiation dosimetry  

DOEpatents

Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via a transmissive fiber which also preferably serves to return the emission from the luminescent sensor. The stimulating beam is advantageously split by a beam splitter to create a detector beam which is measured for power during a reading period during which the luminescent phosphor is read. The detected power is preferably used to control the beam generator to thus produce desired beam power during the reading period. The luminescent emission from the remote sensor is communicated to a suitable emission detector, preferably after filtering or other selective treatment to better isolate the luminescent emission. 8 figures.

Braunlich, P.F.; Tetzlaff, W.; Hegland, J.E.; Jones, S.C.

1991-03-12

14

Dosimetry for quantitative analysis of the effects of low-dose ionizing radiation in radiation therapy patients.  

PubMed

We have developed and validated a practical approach to identifying the location on the skin surface that will receive a prespecified biopsy dose (ranging down to 1 cGy) in support of in vivo biological dosimetry in humans. This represents a significant technical challenge since the sites lie on the patient's surface outside the radiation fields. The PEREGRINE Monte Carlo simulation system was used to model radiation dose delivery, and TLDs were used for validation on phantoms and for confirmation during patient treatment. In the developmental studies, the Monte Carlo simulations consistently underestimated the dose at the biopsy site by approximately 15% (of the local dose) for a realistic treatment configuration, most likely due to lack of detail in the simulation of the linear accelerator outside the main beam line. Using a single, thickness-independent correction factor for the clinical calculations, the average of 36 measurements for the predicted 1-cGy point was 0.985 cGy (standard deviation: 0.110 cGy) despite patient breathing motion and other real-world challenges. Since the 10-cGy point is situated in the region of high-dose gradient at the edge of the field, patient motion had a greater effect, and the six measured points averaged 5.90 cGy (standard deviation: 1.01 cGy), a difference that is equivalent to approximately a 6-mm shift on the patient's surface. PMID:16435922

Lehmann, Joerg; Stern, Robin L; Daly, Thomas P; Rocke, David M; Schwietert, Chad W; Jones, Gregory E; Arnold, Michelle L; Siantar, Christine L Hartmann; Goldberg, Zelanna

2006-02-01

15

The dosimetry of ionizing radiation. Volume 2  

SciTech Connect

This treatise reviews current methodology and theory of radiation measurement and dosimetry and is designed to supplement the three-volume Radiation Dosimetry, Second Edition. To incorporate advances in this changing field, recognized authorities approach the subject with new theoretical insights and applied techniques. The chapters in Volume II include coverage of new detector systems for radiation measurements in neutron and photon fields, as well as techniques for interpreting data; new designs for calorimeters and temperature measurement methods; and new methods for measuring high-intensity pulsed radiation. CONTENTS: Relationship of Microdosimetric Techniques to Applications in Biological Systems; Neutron Spectroscopy; Ionization Chambers; Advances in Calorimetry for Radiation Dosimetry; External Beta-Photon Dosimetry for Radiation Protection; Each chapter includes references. Index.

Kase, K.R.; Bjarngard, B.E.; Attix, F.H.

1987-01-01

16

The Radiofrequency Radiation Dosimetry Handbook: reminiscences.  

PubMed

This paper traces the history of the development of the Radiofrequency Radiation Dosimetry Handbook and its subsequent impact on radio frequency radiation exposure standards. The author's recollections are used to illustrate the behind the scenes efforts of the individuals involved in this project. The development of models at the University of Utah and confirmation of these results by various experimenters led to the publication of four editions of the Radiofrequency Radiation Dosimetry Handbook, i.e., "The RFR Experimenters Bible." PMID:10334710

Allen, S J

1999-01-01

17

Radiation dosimetry onboard the International Space Station ISS.  

PubMed

Besides the effects of the microgravity environment, and the psychological and psychosocial problems encountered in confined spaces, radiation is the main health detriment for long duration human space missions. The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the ones encountered on earth for occupational radiation workers. Therefore the determination and the control of the radiation load on astronauts is a moral obligation of the space faring nations. The requirements for radiation detectors in space are very different to that on earth. Limitations in mass, power consumption and the complex nature of the space radiation environment define and limit the overall construction of radiation detectors. Radiation dosimetry onboard the International Space Station (ISS) is onboard the International Space Station (ISS) is accomplished to one part as "operational" dosimetry accomplished to one part as "operational" dosimetry aiming for area monitoring of the radiation environment as well as astronaut surveillance. Another part focuses on "scientific" dosimetry aiming for a better understanding of the radiation environment and its constitutes. Various research activities for a more detailed quantification of the radiation environment as well as its distribution in and outside the space station have been accomplished in the last years onboard the ISS. The paper will focus on the current radiation detectors onboard the ISS, their results, as well as on future planned activities. PMID:19205296

Berger, Thomas

2008-01-01

18

EDITORIAL: Special issue on radiation dosimetry Special issue on radiation dosimetry  

NASA Astrophysics Data System (ADS)

This special issue of Metrologia on radiation dosimetry is the second in a trilogy on the subject of ionizing radiation measurements, a field that is overseen by Sections I, II and III of the CIPM's Consultative Committee for Ionizing Radiation (CCRI). The work of Section II, on radionuclide metrology, was covered in issue 44(4), published in 2007, and that of Section III, on neutron metrology, will be covered in a special issue to be published shortly. This issue covers the work of Section I (x-rays and ? rays, and charged particles). The proposal to publish special issues of Metrologia covering the work of the CCRI Sections was first made in 2003 and refined at the two subsequent meetings of the CCRI in 2005 and 2007. The overall aim is to present the work of the CCRI to a wider metrological audience and to highlight the relevance and importance of the field. The main focus of our special issue on dosimetry metrology is on the 'state of the art' in the various areas covered, with an indication of the current developments taking place and the problems and challenges that remain. Where appropriate, this is set in a brief historical context, although it is not the aim to give a historical review. The need for accurate measurement has been appreciated from the pioneering days of the use of ionizing radiation in the early 20th century, particularly in the fields of diagnostic and therapeutic medicine. Over the years, the range of applications for ionizing radiation has expanded both in scope and in the types and energies of radiation employed. This has led to the need to develop a wide variety of measurement techniques and standards covering fields ranging from the low doses experienced in environmental and protection applications to the extremely high doses used in industrial processing. The different types of radiation employed give rise to the need for dose measurements in radiation beams whose effective penetration through a material such as water ranges from a few micrometres to several metres. The wide variety of radiation types and dose ranges posed a particular problem in selecting the topics to be included in this special issue and has inevitably meant that some fields of application have received less attention than others. It is hoped, however, that the topics covered are broad and varied enough to provide useful information for those with an interest in radiation dosimetry, both experienced practitioners and those entering the field. The extensive reference lists also provide a valuable resource. The issue begins with the important topic of mutual recognition of dosimetry standards and the procedures that have been put in place to achieve this, and continues with contributions on the principal measurement techniques employed: free-air chambers, air-kerma cavity standards, photon absorbed-dose standards and absorbed-dose standards for electron beams. The topics of brachytherapy and radiation protection dosimetry are covered in separate articles, and the issue concludes with a review of the mathematical modelling techniques that underpin much of the recent work described in the preceding sections. The work involved in the production of a document such as this is considerable and we have been extremely fortunate in securing the involvement of many of the acknowledged experts in the field of ionizing radiation dosimetry, both as named authors and serving as anonymous referees. The editors would like to thank all those who have given their time and commitment to producing this special issue, and particularly Professor Georgio Moscati, former President of the CCRI, and Dr Penny Allisy-Roberts, Executive Secretary of the CCRI, for their support and encouragement.

Sharpe, Peter

2009-04-01

19

Third conference on radiation protection and dosimetry  

SciTech Connect

This conference has been designed with the objectives of promoting communication among applied, research, regulatory, and standards personnel involved in radiation protection and providing them with sufficient information to evaluate their programs. To partly fulfill these objectives, a technical program consisting of more than 75 invited and contributed oral presentations encompassing all aspects of radiation protection has been prepared. General topics include external dosimetry, internal dosimetry, instruments, regulations and standards, accreditation and test programs, research advances, and applied program experience. This publication provides a summary of the technical program and a collection of abstracts of the oral presentations.

Not Available

1991-01-01

20

Holographic interferometry in radiation dosimetry, microprocessor assisted  

NASA Astrophysics Data System (ADS)

In this paper the applications of holographic interferometry to ionizing radiation dosimetry are presented. The determination of the accurate value of dose delivered by an ionizing radiation source (released energy per mass unit) is a complex problem which imposes different solutions depending on the experimental parameters and it is solved with a double exposure holographic interferometric method associated with an optoelectronic interface and Z-80 microprocessor. The method can determine the integral absorbed dose as well as the tridimensional distribution of dose in a given volume. The paper presents some results obtained in radiation dosimetry. Different transparent liquids were used as ionizing radiation transducers. Integral dose and spatial dose-distribution were recorded for equivalent tissue liquids and blood plasma. Boundary phenomena, during a irradiation of successive layers of liquids having different atomic numbers, were investigated.

Nicolau, Silvia; Sporea, Dan G.; Niculescu, V. I. R.

1999-08-01

21

Advanced Semiconductor Dosimetry in Radiation Therapy  

SciTech Connect

Modern radiation therapy is very conformal, resulting in a complexity of delivery that leads to many small radiation fields with steep dose gradients, increasing error probability. Quality assurance in delivery of such radiation fields is paramount and requires real time and high spatial resolution dosimetry. Semiconductor radiation detectors due to their small size, ability to operate in passive and active modes and easy real time multichannel readout satisfy many aspects of in vivo and in a phantom quality assurance in modern radiation therapy. Update on the recent developments and improvements in semiconductor radiation detectors and their application for quality assurance in radiation therapy, based mostly on the developments at the Centre for Medical Radiation Physics (CMRP), University of Wollongong, is presented.

Rosenfeld, Anatoly B. [Centre for Medical Radiation Physics, University of Wollongong, Wollongong NSW 2522 (Australia)

2011-05-05

22

Advanced Semiconductor Dosimetry in Radiation Therapy  

NASA Astrophysics Data System (ADS)

Modern radiation therapy is very conformal, resulting in a complexity of delivery that leads to many small radiation fields with steep dose gradients, increasing error probability. Quality assurance in delivery of such radiation fields is paramount and requires real time and high spatial resolution dosimetry. Semiconductor radiation detectors due to their small size, ability to operate in passive and active modes and easy real time multichannel readout satisfy many aspects of in vivo and in a phantom quality assurance in modern radiation therapy. Update on the recent developments and improvements in semiconductor radiation detectors and their application for quality assurance in radiation therapy, based mostly on the developments at the Centre for Medical Radiation Physics (CMRP), University of Wollongong, is presented.

Rosenfeld, Anatoly B.

2011-05-01

23

Piezo and pyroelectric radiation dosimetry  

Microsoft Academic Search

The use of photoacoustic, piezoelectric, and pyroelectric radiation dosimeters is presented. New results with photoacoustic, pulsed photoacoustic, piezoelectric, and pyroelectric systems are discussed. The characteristics of the new dosimeters developed are compared. A theoretical model to explain the results obtained with the pulsed pyroelectric radiation dosimeter is presented and compared with experimental results. The use of such dosimeters as calorimeters

S. Mascarenhas; A. A. d. Carvalho

1991-01-01

24

Progress in high-dose radiation dosimetry. Final report  

SciTech Connect

The last decade has witnessed a deluge of new high-dose dosimetry techniques and expended applications of methods developed earlier. Many of the principal systems are calibrated by means of calorimetry, although production of heat is not always the final radiation effect of interest. Requirements for a stable and reliable transfer dose meters have led to further developments of several important high-dose systems: thermoluminescent materials, radiochromic dyes, ceric-cerous solutions analyzed by high-frequency oscillometry. A number of other prospective dosimeters are also treated in this review. In addition, an IAEA program of high-dose intercomparison and standardization for industrial radiation processing is described.

Ettinger, K.V.; Nam, J.W.; McLaughlin, W.L.; Chadwick, K.H.

1981-01-01

25

Progress in high-dose radiation dosimetry. Final report  

SciTech Connect

The last decade has witnessed a deluge of new high-dose dosimetry techniques and expended applications of methods developed earlier. Many of the principal systems are calibrated by means of calorimetry, although production of heat is not always the final radiation effect of interest. Requirements for a stable and reliable transfer dose meters have led to further developments of several important high-dose systems: thermoluminescent materials, radiochromic dyes, ceric-cerous solutions analyzed by high-frequency oscillometry. A number of other prospective dosimeters also treated in this review. In addition, an IAEA programme of high-dose intercomparison and standardization for industrial radiation processing is described.

Ettinger, K.V.; Nam, J.W.; McLaughlin, W.L.; Chadwick, K.H.

1981-01-01

26

The radiation dosimetry of Re-186 HEDP  

SciTech Connect

Patients suffering from metastatic bone cancer may be offered some relief of bone pain by several palliative agents currently under study. One such agent is Re-186 HEDP (etidronate). We gathered biodistribution data from 27 patients receiving this agent for palliation of bone pain. Skeletal activity was estimated as that portion of administered activity not recovered in urine or measured in kidneys or extracellular fluid (ECF) space. Activity in kidneys was estimated through scintigraphic imaging. Activity in urine and blood were estimated by direct counting of samples; activity in ECF was approximated as blood activity divided by the plasmacrit, multiplied by 0.2 times body weight. All retention data were fit to a sum of exponentials for estimation of residence times. Activity in the urinary bladder contents was estimated from the urinary excretion data using the dynamic bladder model of Cloutier et al. Estimated residence times were kidneys 0.538 hr, bone 33.3 hr (divided evenly between cortical and trabecular bone for dosimetry purposes), urinary bladder contents 1.18 hr, and remainder of body 6.52hr. Radiation dose estimates were developed, using the MIRDOSE 3 software. Radiation dose estimates for bone surfaces and red marrow are 1.9 and 0.82 mGy/MBq, respectively. The estimate for the urinary bladder wall is 0.57 mGy/MBq. Most other organs` estimates were around 0.02 mGy/MBq. The new marrow dose model presented in MIRDOSE 3 was used to look at the distribution of marrow dose in different bones, and to develop a dose-volume histogram. These data should be used as the basis for the radiation dosimetry of this agent.

Stabin, M.G. [Oak Ridge Inst. for Science and Education, TN (United States); Graham, M.C.; Scher, H.J. [Memorial Sloan-Kettering Cancer Center, NY (United States)

1995-05-01

27

Retrospective biological dosimetry of absorbed radiation.  

PubMed

Frequencies of chromosomal translocations in human peripheral blood lymphocytes irradiated in vitro by 200 kV X rays have been estimated by the fluorescence in situ hybridisation (FISH) technique. Probes specific for whole chromosomes 1, 3 and 4 were labelled with, biotin 16 dUTP + digoxigenin 11 dUTP; biotin 16 dUTP and digoxigenin 11 dUTP respectively, to achieve three colour FISH to distinguish exchanges involving individual chromosomes. The translocation frequencies for individual chromosomes suggested a relationship between the response and the genomic content of the chromosomes studied. Dose-response curves derived from translocations involving all the three painted chromosomes (22.3% of the genome) showed a linear-quadratic response with alpha and beta coefficients of 0.027 +/- 0.009 Gy-1 and 0.033 +/- 0.004 Gy-2, corresponding coefficients for the response curves extrapolated to the entire genome are 0.072 +/- 0.026 Gy-1 and 0.075 +/- 0.011 Gy-2 respectively. Dose-response curves for the induction of dicentrics involving painted chromosomes also showed a similar response, but the dicentric frequencies were consistently lower than the translocation frequencies for all the doses studied. Dose fractionation resulted in a small but significant reduction in the yield of exchanges, thus suggesting repair of some radiation damage during the period between the two fractions. Retrospective biological dosimetry was attempted with FISH assay of five radiation workers with chronically accumulated doses of approximately 500 mSv received over a period of 2-3 decades. Among the 2421 metaphases scored in these subjects 28 translocations involving the painted chromosomes were detected. The dose estimates based on FISH assay ranged from 0.215 +/- 0.116 Gy to 0.635 +/- 0.292 mGy, thus suggesting the usefulness of this assay in retrospective biological dosimetry. PMID:11468799

Rao, B S; Natarajan, A T

2001-01-01

28

The MCART Radiation Physics Core: The Quest for Radiation Dosimetry Standardization  

PubMed Central

Dose-related radiobiological research results can only be meaningfully compared when radiation dosimetry is standardized. To this purpose, the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Medical Countermeasures Against Radiological Threats (MCART) consortium recently created a Radiation Physics Core (RPC) as an entity to assume responsibility of standardizing radiation dosimetry practices among its member laboratories. The animal research activities in these laboratories utilize a variety of ionizing photon beams from several irradiators such as 250–320 kVp x-ray generators, 137Cs irradiators, 60Co teletherapy machines, and medical linear accelerators (LINACs). In addition to this variety of sources, these centers utilize a range of irradiation techniques and make use of different dose calculation schemes to conduct their experiments. An extremely important objective in these research activities is to obtain a Dose Response Relationship (DRR) appropriate to their respective organ-specific models of acute and delayed radiation effects. A clear and unambiguous definition of the DRR is essential for the development of medical countermeasures. It is imperative that these DRRs are transparent between centers. The MCART RPC has initiated the establishment of standard dosimetry practices among member centers and is introducing a Remote Dosimetry Monitoring Service (RDMS) to ascertain ongoing quality assurance. In this paper we will describe the initial activities of the MCART RPC toward implementing these standardization goals. It is appropriate to report a summary of initial activities with the intent of reporting the full implementation at a later date. PMID:24276553

Kazi, Abdul M.; MacVittie, Thomas J.; Lasio, Giovanni; Lu, Wei; Prado, Karl L.

2013-01-01

29

2011 Radiation Epidemiology and Dosimetry Course  

Cancer.gov

2011 - Three-day course intended for people with backgrounds in epidemiology who are interested in learning about the health effects of radiation exposure–particularly the relationship between ionizing radiation and cancer.

30

Proceedings of the third conference on radiation protection and dosimetry  

SciTech Connect

The Third Conference on Radiation Protection and Dosimetry was held during October 21--24, 1991, at the Sheraton Plaza Hotel in Orlando, Florida. This meeting was designed with the objectives of promoting communication among applied, research, regulatory, and standards personnel involved in radiation protection, and providing them with sufficient information to evaluate their programs. To meet these objectives, a technical program consisting of more than 75 invited and contributed oral presentations encompassing all aspects of radiation protection was prepared. General topics considered in the technical session included external dosimetry, internal dosimetry, instruments, accident dosimetry, regulations and standards, research advances, and applied program experience. In addition, special sessions were held to afford attendees the opportunity to make short presentations of recent work or to discuss topics of general interest. Individual reports are processed separately on the database.

Swaja, R.E.; Sims, C.S.; Casson, W.H. [eds.

1991-10-01

31

Proceedings of the Third Conference on Radiation Protection and Dosimetry  

NASA Astrophysics Data System (ADS)

The Third Conference on Radiation Protection and Dosimetry was held during October 21-24, 1991, at the Sheraton Plaza Hotel in Orlando, Florida. This meeting was designed with the objectives of promoting communication among applied, research, regulatory, and standards personnel involved in radiation protection, and providing them with sufficient information to evaluate their programs. To meet these objectives, a technical program consisting of more than 75 invited and contributed oral presentations encompassing all aspects of radiation protection was prepared. General topics considered in the technical session included external dosimetry, internal dosimetry, instruments, accident dosimetry, regulations and standards, research advances, and applied program experience. In addition, special sessions were held to afford attendees the opportunity to make short presentations of recent work or to discuss topics of general interest. Individual reports are processed separately on the database.

Swaja, R. E.; Sims, C. S.; Casson, W. H.

1991-10-01

32

Radiation Protection Dosimetry Vol. 97, No. 1, pp. 6973 (2001)  

E-print Network

69 Radiation Protection Dosimetry Vol. 97, No. 1, pp. 69­73 (2001) Nuclear Technology Publishing BIOMARKERS SPECIFIC TO DENSELY-IONISING (HIGH LET) RADIATIONS D. J. Brenner, N. Okladnikova, P. Hande, L -- There have been several suggestions of biomarkers that are specific to high LET radiation. Such a biomarker

Brenner, David Jonathan

33

Medical Radiation Dosimetry: Concepts and Needs  

SciTech Connect

Radiation is used widely used in medicine for diagnostic and therapeutic applications. Both the desired effects and the potential detrimental side effects depend on the radiation dose delivered. As such it is essential to determining the radiation dose received by patients as accurately as needed to optimise the radiation procedure. Solid state dosimeters are increasingly used in medicine because of their small physical size, high sensitivity and usually low cost. Combining multiple detectors allows the detection of radiation dose distributions, an application where the distinction between radiation dosimeter and image detector starts to blur. Given the rapid development of detector technology it can be expected that the utilisation of solid-state dosimeters in medicine will continue to increase.

Kron, Tomas [Peter MacCallum Cancer Centre, Department of Physical Sciences, St Andrews Place, East Melbourne, Victoria 3002 (Australia)

2011-05-05

34

Space radiation dosimetry in low-Earth orbit and beyond.  

PubMed

Space radiation dosimetry presents one of the greatest challenges in the discipline of radiation protection. This is a result of both the highly complex nature of the radiation fields encountered in low-Earth orbit (LEO) and interplanetary space and of the constraints imposed by spaceflight on instrument design. This paper reviews the sources and composition of the space radiation environment in LEO as well as beyond the Earth's magnetosphere. A review of much of the dosimetric data that have been gathered over the last four decades of human space flight is presented. The different factors affecting the radiation exposures of astronauts and cosmonauts aboard the International Space Station (ISS) are emphasized. Measurements made aboard the Mir Orbital Station have highlighted the importance of both secondary particle production within the structure of spacecraft and the effect of shielding on both crew dose and dose equivalent. Roughly half the dose on ISS is expected to come from trapped protons and half from galactic cosmic rays (GCRs). The dearth of neutron measurements aboard LEO spacecraft and the difficulty inherent in making such measurements have led to large uncertainties in estimates of the neutron contribution to total dose equivalent. Except for a limited number of measurements made aboard the Apollo lunar missions, no crew dosimetry has been conducted beyond the Earth's magnetosphere. At the present time we are forced to rely on model-based estimates of crew dose and dose equivalent when planning for interplanetary missions, such as a mission to Mars. While space crews in LEO are unlikely to exceed the exposure limits recommended by such groups as the NCRP, dose equivalents of the same order as the recommended limits are likely over the course of a human mission to Mars. PMID:11863032

Benton, E R; Benton, E V

2001-09-01

35

Radiation Protection Dosimetry Vol. 100, Nos 14, pp. 207209 (2002)  

E-print Network

207 Radiation Protection Dosimetry Vol. 100, Nos 1­4, pp. 207­209 (2002) Nuclear Technology for radiation detectors and solid state dosemeters. In previous work, mainly thermoluminescence (TL) methods§ School of Physics & Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel Nuclear Technology Division

Chen, Reuven

36

Recommended improvements to the DS02 dosimetry system's calculation of organ doses and their potential advantages for the Radiation Effects Research Foundation.  

PubMed

The Radiation Effects Research Foundation (RERF) uses a dosimetry system to calculate radiation doses received by the Japanese atomic bomb survivors based on their reported location and shielding at the time of exposure. The current system, DS02, completed in 2003, calculates detailed doses to 15 particular organs of the body from neutrons and gamma rays, using new source terms and transport calculations as well as some other improvements in the calculation of terrain and structural shielding, but continues to use methods from an older system, DS86, to account for body self-shielding. Although recent developments in models of the human body from medical imaging, along with contemporary computer speed and software, allow for improvement of the calculated organ doses, before undertaking changes to the organ dose calculations, it is important to evaluate the improvements that can be made and their potential contribution to RERF's research. The analysis provided here suggests that the most important improvements can be made by providing calculations for more organs or tissues and by providing a larger series of age- and sex-specific models of the human body from birth to adulthood, as well as fetal models. PMID:22262817

Cullings, Harry M

2012-03-01

37

Twenty new ISO standards on dosimetry for radiation processing  

NASA Astrophysics Data System (ADS)

Twenty standards on essentially all aspects of dosimetry for radiation processing were published as new ISO standards in December 1998. The standards are based on 20 standard practices and guides developed over the past 14 years by Subcommittee E10.01 of the American Society for Testing and Materials (ASTM). The transformation to ISO standards using the 'fast track' process under ISO Technical Committee 85 (ISO/TC85) commenced in 1995 and resulted in some overlap of technical information between three of the new standards and the existing ISO Standard 11137 Sterilization of health care products — Requirements for validation and routine control — Radiation sterilization. Although the technical information in these four standards was consistent, compromise wording in the scopes of the three new ISO standards to establish precedence for use were adopted. Two of the new ISO standards are specifically for food irradiation applications, but the majority apply to all forms of gamma, X-ray, and electron beam radiation processing, including dosimetry for sterilization of health care products and the radiation processing of fruit, vegetables, meats, spices, processed foods, plastics, inks, medical wastes, and paper. Most of the standards provide exact procedures for using individual dosimetry systems or for characterizing various types of irradiation facilities, but one covers the selection and calibration of dosimetry systems, and another covers the treatment of uncertainties using the new ISO Type A and Type B evaluations. Unfortunately, nine of the 20 standards just adopted by the ISO are not the most recent versions of these standards and are therefore already out of date. To help solve this problem, efforts are being made to develop procedures to coordinate the ASTM and ISO development and revision processes for these and future ASTM-originating dosimetry standards. In the meantime, an additional four dosimetry standards have recently been published by the ASTM but have not yet been submitted to the ISO, and six more dosimetry standards are under development.

Farrar, H., IV

2000-03-01

38

Radiation dosimetry for the Gemini program  

NASA Technical Reports Server (NTRS)

The principal source of radiation for low-earth-orbit, low inclination space flights is in the area of the South Atlantic magnetic anomaly. None of the Gemini dose measurements reported in the paper are of high enough intensity to be considered hazardous. There is a trend toward larger doses as missions are flown higher and longer. Extended orbital operations between 1400 and 4400 kilometers would encounter high interior radiation levels. Pronounced spacecraft geometry effects have been measured in manned spacecraft. Instrumentation for radiation measurements on Gemini spacecraft is described.

Richmond, R. G.

1972-01-01

39

Radiation sensitive scintillator\\/optical fibre system for radiation dosimetry in burning plasma machine  

Microsoft Academic Search

A possibility of applying a compact radiation dosimetry system to burning plasma machines, such as detecting high energy neutrons and gamma-rays with a wide dynamic range at elevated temperatures, has been studied, utilizing radiation resistant optical fibres and radioluminescence (radiation-induced luminescence) materials. Appropriate radioluminescence materials were found for dosimetry of each radiation field, namely, gamma-rays and neutrons. Especially, a high-energy

T. Shikama; K. Toh; S. Nagata; B. Tsuchiya; M. Yamauchi; T. Nishitani; T. Suzuki; K. Okamoto; N. Kubo

2006-01-01

40

Third conference on radiation protection and dosimetry. Program and abstracts  

SciTech Connect

This conference has been designed with the objectives of promoting communication among applied, research, regulatory, and standards personnel involved in radiation protection and providing them with sufficient information to evaluate their programs. To partly fulfill these objectives, a technical program consisting of more than 75 invited and contributed oral presentations encompassing all aspects of radiation protection has been prepared. General topics include external dosimetry, internal dosimetry, instruments, regulations and standards, accreditation and test programs, research advances, and applied program experience. This publication provides a summary of the technical program and a collection of abstracts of the oral presentations.

Not Available

1991-12-31

41

Personnel radiation dosimetry symposium: program and abstracts  

SciTech Connect

The purpose was to provide applied and research dosimetrists with sufficient information to evaluate the status and direction of their programs relative to the latest guidelines and techniques. A technical program was presented concerning experience, requirements, and advances in gamma, beta, and neutron personnel dosimetry.

Not Available

1984-10-01

42

Radiation protection and dosimetry issues in the medical applications of ionizing radiation  

NASA Astrophysics Data System (ADS)

The technological advances that occurred during the last few decades paved the way to the dissemination of CT-based procedures in radiology, to an increasing number of procedures in interventional radiology and cardiology as well as to new techniques and hybrid modalities in nuclear medicine and in radiotherapy. These technological advances encompass the exposure of patients and medical staff to unprecedentedly high dose values that are a cause for concern due to the potential detrimental effects of ionizing radiation to the human health. As a consequence, new issues and challenges in radiological protection and dosimetry in the medical applications of ionizing radiation have emerged. The scientific knowledge of the radiosensitivity of individuals as a function of age, gender and other factors has also contributed to raising the awareness of scientists, medical staff, regulators, decision makers and other stakeholders (including the patients and the public) for the need to correctly and accurately assess the radiation induced long-term health effects after medical exposure. Pediatric exposures and their late effects became a cause of great concern. The scientific communities of experts involved in the study of the biological effects of ionizing radiation have made a strong case about the need to undertake low dose radiation research and the International System of Radiological Protection is being challenged to address and incorporate issues such as the individual sensitivities, the shape of dose-response relationship and tissue sensitivity for cancer and non-cancer effects. Some of the answers to the radiation protection and dosimetry issues and challenges in the medical applications of ionizing radiation lie in computational studies using Monte Carlo or hybrid methods to model and simulate particle transport in the organs and tissues of the human body. The development of sophisticated Monte Carlo computer programs and voxel phantoms paves the way to an accurate dosimetric assessment of the medical applications of ionizing radiation. In this paper, the aforementioned topics will be reviewed. The current status and the future trends in the implementation of the justification and optimization principles, pillars of the International System of Radiological Protection, in the medical applications of ionizing radiation will be discussed. Prospective views will be provided on the future of the system of radiological protection and on dosimetry issues in the medical applications of ionizing radiation.

Vaz, Pedro

2014-11-01

43

Effect of Brain Stem and Dorsal Vagus Complex Dosimetry on Nausea and Vomiting in Head and Neck Intensity-Modulated Radiation Therapy  

SciTech Connect

Intensity-modulated radiation therapy (IMRT) is becoming the treatment of choice for many head and neck cancer patients. IMRT reduces some toxicities by reducing radiation dose to uninvolved normal tissue near tumor targets; however, other tissues not irradiated using previous 3D techniques may receive clinically significant doses, causing undesirable side effects including nausea and vomiting (NV). Irradiation of the brainstem, and more specifically, the area postrema and dorsal vagal complex (DVC), has been linked to NV. We previously reported preliminary hypothesis-generating dose effects associated with NV in IMRT patients. The goal of this study is to relate brainstem dose to NV symptoms. We retrospectively studied 100 consecutive patients that were treated for oropharyngeal cancer with IMRT. We contoured the brainstem, area postrema, and DVC with the assistance of an expert diagnostic neuroradiologist. We correlated dosimetry for the 3 areas contoured with weekly NV rates during IMRT. NV rates were significantly higher for patients who received concurrent chemotherapy. Post hoc analysis demonstrated that chemoradiation cases exhibited a trend towards the same dose-response relationship with both brainstem mean dose (p = 0.0025) and area postrema mean dose (p = 0.004); however, both failed to meet statistical significance at the p {<=} 0.002 level. Duration of toxicity was also greater for chemoradiation patients, who averaged 3.3 weeks with reported Common Terminology Criteria for Adverse Events (CTC-AE), compared with an average of 2 weeks for definitive RT patients (p = 0.002). For definitive RT cases, no dose-response trend could be ascertained. The mean brainstem dose emerged as a key parameter of interest; however, no one dose parameter (mean/median/EUD) best correlated with NV. This study does not address extraneous factors that would affect NV incidence, including the use of antiemetics, nor chemotherapy dose schedule specifics before and during RT. A prospective study will be required to depict exactly how IMRT dose affects NV.

Ciura, Katherine; McBurney, Michelle; Nguyen, Baongoc [School of Health Sciences, Medical Dosimetry Program, Department of Radiation Oncology, Anderson Cancer Center, Houston, TX (United States); Pham, Mary, E-mail: mary.pham@mdanderson.or [School of Health Sciences, Medical Dosimetry Program, Department of Radiation Oncology, Anderson Cancer Center, Houston, TX (United States); Rebueno, Neal [Department of Diagnostic Radiology, University of Texas M.D. Anderson Cancer Center, Houston (United States); Fuller, Clifton D.; Guha-Thakurta, Nandita [Department of Radiation Oncology, University of Texas Health Science Center, San Antonio, TX (United States); Rosenthal, David I. [Department of Diagnostic Radiology, University of Texas M.D. Anderson Cancer Center, Houston (United States)

2011-04-01

44

Fostering a culture of interprofessional education for radiation therapy and medical dosimetry students  

SciTech Connect

A less-studied aspect of radiation therapy and medical dosimetry education is experiential learning through attendance at interprofessional conferences. University of North Carolina radiation therapy and medical dosimetry students regularly attended morning conferences and daily pretreatment peer review, including approximately 145 hours of direct interaction with medical attending physicians and residents, medical physicists, and other faculty. We herein assessed the effect of their participation in these interprofessional conferences on knowledge and communication. The students who graduated from our radiation therapy and medical dosimetry programs who were exposed to the interprofessional education initiative were compared with those who graduated in the previous years. The groups were compared with regard to their knowledge (as assessed by grades on end-of-training examinations) and team communication (assessed via survey). The results for the 2 groups were compared via exact tests. There was a trend for the examination scores for the 2012 cohort to be higher than for the 2007 to 2011 groups. Survey results suggested that students who attended the interprofessional education sessions were more comfortable speaking with attending physicians, residents, physicists, and faculty compared with earlier students who did not attend these educational sessions. Interprofessional education, particularly vertical integration, appears to provide an enhanced educational experience both in regard to knowledge (per the examination scores) and in building a sense of communication (via the survey results). Integration of interprofessional education into radiation therapy and medical dosimetry educational programs may represent an opportunity to enrich the learning experience in multiple ways and merits further study.

Lavender, Charlotte, E-mail: charlavender@gmail.com; Miller, Seth; Church, Jessica; Chen, Ronald C.; Muresan, Petronella A.; Adams, Robert D.

2014-04-01

45

A GENERALIZED CONCEPT FOR RADIATION DOSIMETRY  

Microsoft Academic Search

The Bragg-Gray principle was successfully employed to measure the ; absorbed dose in varlous kinds of matter for ionizing radiation over a wide range ; of energy. However, with the present large scale application of different types ; of ionizing radiation and the resulting more stringent requirements for the ; protection of man against these radiations, it is desirable to

G. S. Hurst; R. H. Ritchie

1962-01-01

46

WHOLE-BODY DOSIMETRY OF MICROWAVE RADIATION IN SMALL ANIMALS: THE EFFECT OF BODY MASS AND EXPOSURE GEOMETRY  

EPA Science Inventory

Whole-body absorption of 2450-MHz radiation was measured in rats that ranged from 6 to 440 grams and mice that ranged from 30 to 50 grams. Simultaneous exposure of groups of animals in varying numbers and various configurations were made under free-field conditions in an electric...

47

Internal radiation dosimetry for clinical testing of radiolabeled monoclonal antibodies  

SciTech Connect

In gauging the efficacy of radiolabeled monoclonal antibodies in cancer treatment, it is important to know the amount of radiation energy absorbed by tumors and normal tissue per unit administered activity. This paper describes methods for estimating absorbed doses to human tumors and normal tissues, including intraperitoneal tissue surfaces, red marrow, and the intestinal tract from incorporated radionuclides. These methods use the Medical Internal Radiation Dose (MIRD) scheme; however, they also incorporate enhancements designed to solve specific dosimetry problems encountered during clinical studies, such as patient-specific organ masses obtained from computerized tomography (CT) volumetrics, estimates of the dose to tumor masses within normal organs, and multicellular dosimetry for studying dose inhomogeneities in solid tumors. Realistic estimates of absorbed dose are provided within the short time requirements of physicians so that decisions can be made with regard to patient treatment and procurement of radiolabeled antibodies. Some areas in which further research could improve dose assessment are also discussed. 16 refs., 3 figs.

Fisher, D.R.; Durham, J.S.; Hui, T.E.; Hill, R.L.

1990-11-01

48

Radiation dosimetry for bolus administration of oxygen-15-water  

SciTech Connect

The authors describe the development of a biokinetic model which permits an estimation of organ activities and the dosimetry of a bolus of {sup 15}O-water. The aim of this study was to estimate time-activity functions and deduce the cumulated activities in different organs so that the radiation absorbed dose values can be estimated. The model used includes the right heart chambers, lungs, left heart chambers, brain, liver, kidneys, muscles, gasrointestinal tract and the remainder of the body. Activity in an organ will decay by physical decay with the decay constant, {gamma}, and can diffuse in the organ. An exception is the heart, where blood is ejected from the heart chambers. Depending on the location of the organ in relation to the blood sampling point, organ activities can be calculated by convolution or deconvolution. The radiation absorbed dose values were estimated and an effective dose equivalent H{sub E} of 1.16 {mu}Sv/MBq (4.32 mrem/mCi) as well as an effective dose E of 1.15 {mu}Sv/MBq (4.25 mrem/mCi) were calculated. The cumulated activities in select organs measured by PET gave good agreement with the values calculated by this model. The values of effective dose equivalent and effective dose for bolus administration of {sup 15}O-water calculated from the absorbed doses estimated by the proposed kinetic model are almost three times higher than those previously published. A total of 8700 MBq (235 mCi) of {sup 15}O-water can be administered if an effective dose of 10 mSv (1 rem) is accepted. 32 refs., 5 figs., 2 tabs.

Brihaye, C.; Depresseux, J.C.; Comar, D. [Universite de Liege (Belgium)

1995-04-01

49

High LET, passive space radiation dosimetry and spectrometry  

NASA Technical Reports Server (NTRS)

The development of high linear energy transfer (LET), passive radiation dosimetry and spectrometry is needed for the purpose of accurate determination of equivalent doses and assessment of health risks to astronauts on long duration missions. Progress in the following research areas is summerized: intercomparisons of cosmic ray equivalent dose and LET spectra measurements between STS missions and between astronauts; increases LET spectra measurement accuracy with ATAS; space radiation measurements for intercomparisons of passive (PNTD, TLD, TRND, Emulsion) and active (TEPC, RME-111) dosimeters; interaction of cosmic ray particles with nuclei in matter; radiation measurements after long duration space exposures; ground based dosimeter calibrations; neutron detector calibrations; radiation measurements on Soviet/Russian spacecraft; space radiation measurements under thin shielding; and space radiation.

Benton, E. V.; Frank, A. L.; Benton, E. R.; Keegan, R. P.; Frigo, L. A.; Sanner, D.; Rowe, V.

1995-01-01

50

Effect of Normal Lung Definition on Lung Dosimetry and Lung Toxicity Prediction in Radiation Therapy Treatment Planning  

SciTech Connect

Purpose: This study aimed to compare lung dose–volume histogram (DVH) parameters such as mean lung dose (MLD) and the lung volume receiving ?20 Gy (V20) of commonly used definitions of normal lung in terms of tumor/target subtraction and to determine to what extent they differ in predicting radiation pneumonitis (RP). Methods and Materials: One hundred lung cancer patients treated with definitive radiation therapy were assessed. The gross tumor volume (GTV) and clinical planning target volume (PTV{sub c}) were defined by the treating physician and dosimetrist. For this study, the clinical target volume (CTV) was defined as GTV with 8-mm uniform expansion, and the PTV was defined as CTV with an 8-mm uniform expansion. Lung DVHs were generated with exclusion of targets: (1) GTV (DVH{sub G}); (2) CTV (DVH{sub C}); (3) PTV (DVH{sub P}); and (4) PTV{sub c} (DVH{sub Pc}). The lung DVHs, V20s, and MLDs from each of the 4 methods were compared, as was their significance in predicting radiation pneumonitis of grade 2 or greater (RP2). Results: There are significant differences in dosimetric parameters among the various definition methods (all Ps<.05). The mean and maximum differences in V20 are 4.4% and 12.6% (95% confidence interval 3.6%-5.1%), respectively. The mean and maximum differences in MLD are 3.3 Gy and 7.5 Gy (95% confidence interval, 1.7-4.8 Gy), respectively. MLDs of all methods are highly correlated with each other and significantly correlated with clinical RP2, although V20s are not. For RP2 prediction, on the receiver operating characteristic curve, MLD from DVH{sub G} (MLD{sub G}) has a greater area under curve of than MLD from DVH{sub C} (MLD{sub C}) or DVH{sub P} (MLD{sub P}). Limiting RP2 to 30%, the threshold is 22.4, 20.6, and 18.8 Gy, for MLD{sub G}, MLD{sub C}, and MLD{sub P}, respectively. Conclusions: The differences in MLD and V20 from various lung definitions are significant. MLD from the GTV exclusion method may be more accurate in predicting clinical significant radiation pneumonitis.

Wang, Weili [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiation Oncology, the Fourth Affiliated Hospital, China Medical University, Shenyang (China); Xu, Yaping [Department of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou (China); Schipper, Matthew; Matuszak, Martha M. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Ritter, Timothy [Department of Radiation Oncology, Veteran Administration Hospital, Ann Arbor, Michigan (United States); Cao, Yue; Ten Haken, Randall K. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Kong, Feng-Ming, E-mail: fkong@gru.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiation Oncology, Veteran Administration Hospital, Ann Arbor, Michigan (United States)

2013-08-01

51

Electron paramagnetic resonance biophysical radiation dosimetry with tooth enamel  

NASA Astrophysics Data System (ADS)

This thesis deals with advancements made in the field of Electron Paramagnetic Resonance (EPR) for biophysical dosimetry with tooth enamel for accident, emergency and retrospective radiation dose reconstruction. A methodology has been developed to measure retrospective radiation exposures in human tooth enamel. This entails novel sample preparation procedures with minimum mechanical treatment to reduce the preparation induced uncertainties, establish optimum measurement conditions inside the EPR cavity, post process the measured spectrum with functional simulation of dosimetric and other interfering signals, and reconstruct dose. By using this technique, retrospective gamma radiation exposures as low as 80 +/- 30 mGy have been successfully deciphered. The notion of dose modifier was introduced in EPR biodosimetry for low dose measurements. It has been demonstrated that by using the modified zero added dose (MZAD) technique for low radiation exposures, doses in the 100 mGy range can be easily reconstructed in teeth which were previously thought useless for EPR dosimetry. Also the use of a dose modifier makes robust dose reconstruction possible for higher radiation exposures. The EPR dosimetry technique was also developed for tooth samples extracted from rodents, which represent small tooth sizing. EPR doses in the molars, extracted from mice irradiated with whole body exposures, were reassessed and shown to be correct within the experimental uncertainty. The sensitivity of human tooth enamel for neutron irradiation, obtained from the 3 MV McMaster K. N. Van de Graaff accelerator, was also studied. For the first time this work has shown that the neutron sensitivity of the tooth enamel is approximately 1/10th of the equivalent gamma sensitivity. Parametric studies for neutron dose rate and neutron energy within the available range of the accelerator, showed no impact on the sensitivity of the tooth enamel. Therefore, tooth enamel can be used as a dosimeter for both neutrons as well as gamma radiation. We will continue experiments to develop this endpoint as a sensitive accident or emergency tool for our response capabilities.

Khan, Rao F. H.

52

Nuclear data needs for radiation protection and therapy dosimetry  

SciTech Connect

New nuclear data are required for improved neutron and proton radiotherapy treatment planning as well as future applications of high-energy particle accelerators. Modern neutron radiotherapy employs energies extending to 70 MeV, while industrial applications such as transmutation and tritium breeding may generate neutrons exceeding energies of 100 MeV. Secondary neutrons produced by advanced proton therapy facilities can have energies as high as 250 MeV. Each use requires nuclear data for transport calculations and analysis of radiation effects (dosimetry). We discuss the nuclear data needs supportive of these applications including the different information requirements. As data in this energy region are sparse and likely to remain so, advanced nuclear model calculations can provide some of the needed information. ln this context, we present new evaluated nuclear data for C, N, and O. Additional experimental information, including integral and differential data, are required to confirm these results and to bound further calculations. We indicate the required new data to be measured and the difficulties in carrying out such experiments.

Chadwick, M.B. [Lawrence Livermore National Lab., CA (United States); DeLuca, P.M. Jr. [Wisconsin Univ., Madison, WI (United States). Dept of Medical Physics; Haight, R.C. [Los Alamos National Lab., NM (United States)

1995-12-31

53

Mixed radiation field dosimetry utilizing Nuclear Quadrupole Resonance  

SciTech Connect

This project has proposed to develop a novel dosimetry system that is capable of directly evaluating the chemical/biological damage caused by neutrons, photons, or both in a single measurement. The dosimeter itself will consist of a small volume of biological equivalent material that is probed for radiation damage with Nuclear Quadrupole Resonance (NQR) techniques. NQR has previously been utilized as a sensitive probe of structural and chemical changes at the molecular level for a variety of organic compounds. The biological equivalent materials used in this study will not only have a density similar to tissue (tissue equivalent) but will have the same atomic components as tissue. This is a significant requirement if the important neutron interactions that occur in tissue are to occur in the dosimeter as well. The overall objective of this study is to investigate a methodology to perform accurate mixed-field (neutron and photon) dosimetry for biological systems.

Hintenlang, D.

1991-01-01

54

Effect of processor temperature on film dosimetry  

SciTech Connect

Optical density (OD) of a radiographic film plays an important role in radiation dosimetry, which depends on various parameters, including beam energy, depth, field size, film batch, dose, dose rate, air film interface, postexposure processing time, and temperature of the processor. Most of these parameters have been studied for Kodak XV and extended dose range (EDR) films used in radiation oncology. There is very limited information on processor temperature, which is investigated in this study. Multiple XV and EDR films were exposed in the reference condition (d{sub max.}, 10 Multiplication-Sign 10 cm{sup 2}, 100 cm) to a given dose. An automatic film processor (X-Omat 5000) was used for processing films. The temperature of the processor was adjusted manually with increasing temperature. At each temperature, a set of films was processed to evaluate OD at a given dose. For both films, OD is a linear function of processor temperature in the range of 29.4-40.6 Degree-Sign C (85-105 Degree-Sign F) for various dose ranges. The changes in processor temperature are directly related to the dose by a quadratic function. A simple linear equation is provided for the changes in OD vs. processor temperature, which could be used for correcting dose in radiation dosimetry when film is used.

Srivastava, Shiv P. [Department of Radiation Oncology, Reid Hospital and Health Care Services, Richmond, IN (United States); Das, Indra J., E-mail: idas@iupui.edu [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)

2012-07-01

55

Radiation dosimetry of radioimmunotherapy antibodies conjugated with (90)Y  

NASA Astrophysics Data System (ADS)

The ultimate objective of radiation dosimetry in the treatment of cancer is to predict the biological effects of energy deposited in cells. Radioimmunotherapy (RIT) is rapidly attracting interest as a potential new technique for cancer therapy. sp{90}Y is a potential conjugate isotope for tumor-seeking antibodies (Monoclonal antibodies). In this work, the beta dose kernel of sp{90}Y was calculated using MCNP-4B. The established correlation of beta point kernel could be then used to calculate the conventional dose distribution from the sp{90}Y activity distribution within a tumor mass. In general, the calculated point kernel is in good agreement with the published data. The activity distribution is not uniform and there are regions where there is low or no activity. These regions are known as cold-regions. The effect of the cold-regions on the therapeutic dose was studied for sp{90}Y. Calculations of microdosimetric quantities are important in an attempt to infer the mechanisms of the biological effect of ionizing radiation. In this work, the single event distributions, fsb1(z), are evaluated for sp{90}Y for two different radiotherapy cases. The first is for an isolated cancer cell with sp{90}Y bonded to the antigen at the cell surface; in this case no cross-fire effect is considered from the possible sp{90}Y attached to the surrounding cells (e.g., simulating Leukemia). The second case where the cross-fire effect is considered (e.g., simulating solid-tumors) by assuming a uniform distribution of sp{90}Y within the radiation equilibrium region of the tumor mass. The calculations were performed using the electron transport Monte Carlo code (EMCS) which is specially developed for this purpose. In each of the two cases, the single event spectrum was evaluated for both the whole cell and the cell-nucleus. EMCS simulates the electron tracks in water-vapor down to the lowest vibrational excitation energy (0.198 eV). Extension of the tracking to low energies is another significant aspect of the work. Appropriate electron interaction cross sections were developed to enable these calculations.

Al-Hussan, Khalid A. I. Eleissa

56

Computer Aided Dosimetry and Verification of Exposure to Radiation  

NASA Astrophysics Data System (ADS)

In the timeframe following the September 11th attacks on the United States, increased emphasis has been placed on Chemical, Biological, Radiological and Nuclear (CBRN) preparedness. Of prime importance is rapid field assessment of potential radiation exposure to Canadian Forces field personnel. This work set up a framework for generating an 'expert' computer system for aiding and assisting field personnel in determining the extent of radiation insult to military personnel. Data was gathered by review of the available literature, discussions with medical and health physics personnel having hands-on experience dealing with radiation accident victims, and from experience of the principal investigator. Flow charts and generic data fusion algorithms were developed. Relationships between known exposure parameters, patient interview and history, clinical symptoms, clinical work-ups, physical dosimetry, biological dosimetry, and dose reconstruction as critical data indicators were investigated. The data obtained was examined in terms of information theory. A main goal was to determine how best to generate an adaptive model (i.e. when more data becomes available, how is the prediction improved). Consideration was given to determination of predictive algorithms for health outcome. In addition. the concept of coding an expert medical treatment advisor system was developed (U)

Waller, Edward; Stodilka, Robert Z.; Leach, Karen E.; Lalonde, Louise

2002-06-01

57

Reactor dosimetry. ASTM STP 1228  

SciTech Connect

Important advances have been made over the past three decades in neutron and gamma physics and dosimetry. Most of this has been done in support of reactor development programs and the enhanced understanding of radiation damage to reactor fuels, materials, and components. The eighth symposium provided an update of the field of reactor dosimetry. Experts were specifically invited to discuss their latest results under the broad theme of dosimetry for the correlation of radiation effects. This volume has been divided into the following sections: pressure vessel surveillance dosimetry; neutron dosimetry techniques--passive; neutron dosimetry techniques--active; benchmarks; gamma-ray dosimetry techniques; radiation field characterization; nuclear data; and high energy neutron dosimetry. Separate abstracts were prepared for 75 papers in this book.

Farrar, H. IV; Lippincott, E.P.; Williams, J.G.; Vehar, D.W. [eds.

1994-12-31

58

In vivo EPR tooth dosimetry for triage after a radiation event involving large populations.  

PubMed

The management of radiation injuries following a catastrophic event where large numbers of people may have been exposed to life-threatening doses of ionizing radiation will rely critically on the availability and use of suitable biodosimetry methods. In vivo electron paramagnetic resonance (EPR) tooth dosimetry has a number of valuable and unique characteristics and capabilities that may help enable effective triage. We have produced a prototype of a deployable EPR tooth dosimeter and tested it in several in vitro and in vivo studies to characterize the performance and utility at the state of the art. This report focuses on recent advances in the technology, which strengthen the evidence that in vivo EPR tooth dosimetry can provide practical, accurate, and rapid measurements in the context of its intended use to help triage victims in the event of an improvised nuclear device. These advances provide evidence that the signal is stable, accurate to within 0.5 Gy, and can be successfully carried out in vivo. The stability over time of the radiation-induced EPR signal from whole teeth was measured to confirm its long-term stability and better characterize signal behavior in the hours following irradiation. Dosimetry measurements were taken for five pairs of natural human upper central incisors mounted within a simple anatomic mouth model that demonstrates the ability to achieve 0.5 Gy standard error of inverse dose prediction. An assessment of the use of intact upper incisors for dose estimation and screening was performed with volunteer subjects who have not been exposed to significant levels of ionizing radiation and patients who have undergone total body irradiation as part of bone marrow transplant procedures. Based on these and previous evaluations of the performance and use of the in vivo tooth dosimetry system, it is concluded that this system could be a very valuable resource to aid in the management of a massive radiological event. PMID:24711003

Williams, Benjamin B; Flood, Ann Barry; Salikhov, Ildar; Kobayashi, Kyo; Dong, Ruhong; Rychert, Kevin; Du, Gaixin; Schreiber, Wilson; Swartz, Harold M

2014-05-01

59

A new method of retrospective radiation dosimetry: Optically stimulated luminescence in dental enamel  

SciTech Connect

Currently, retrospective biophysical radiation dosimetry lacks a technique that is sensitive, non-invasive, and portable. This has made reliable cause and effect relationships between radiation exposure and its outcomes in humans difficult to establish. Since optical technology is amenable to miniaturization, a search for optically stimulated luminescence in dental enamel was begun. The first successful detection of time dependent optically stimulated luminescence from {gamma} irradiated enamel was accomplished. This luminescence is absent in enamel that is not irradiated or that was heated following irradiation. Thermoluminescence observations were made concurrently with the optical measurements which clarified the role of the organic component of enamel. 20 refs., 5 figs.

Godfrey-Smith, D.I.; Pass, B. [Dalhousie Univ., Halifax (Canada)

1997-05-01

60

Real-time dosimetry in external beam radiation therapy  

PubMed Central

With growing complexity in radiotherapy treatment delivery, it has become mandatory to check each and every treatment plan before implementing clinically. This process is currently administered by an independent secondary check of all treatment parameters and as a pre-treatment quality assurance (QA) check for intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy treatment plans. Although pre-treatment IMRT QA is aimed to ensure the correct dose is delivered to the patient, it does not necessarily predict the clinically relevant patient dose errors. During radiotherapy, treatment uncertainties can affect tumor control and may increase complications to surrounding normal tissues. To combat this, image guided radiotherapy is employed to help ensure the plan conditions are mimicked on the treatment machine. However, it does not provide information on actual delivered dose to the tumor volume. Knowledge of actual dose delivered during treatment aid in confirming the prescribed dose and also to replan/reassess the treatment in situations where the planned dose is not delivered as expected by the treating physician. Major accidents in radiotherapy would have been averted if real time dosimetry is incorporated as part of the routine radiotherapy procedure. Of late real-time dosimetry is becoming popular with complex treatments in radiotherapy. Real-time dosimetry can be either in the form of point doses or planar doses or projected on to a 3D image dataset to obtain volumetric dose. They either provide entrance dose or exit dose or dose inside the natural cavities of a patient. In external beam radiotherapy, there are four different established platforms whereby the delivered dose information can be obtained: (1) Collimator; (2) Patient; (3) Couch; and (4) Electronic Portal Imaging Device. Current real-time dosimetric techniques available in radiotherapy have their own advantages and disadvantages and a combination of one or more of these methods provide vital information about the actual dose delivered to radiotherapy patients. PMID:24179630

Prabhakar, Ramachandran

2013-01-01

61

ELECTRON PARAMAGNETIC RESONANCE DOSIMETRY FOR A LARGE-SCALE RADIATION INCIDENT  

PubMed Central

With possibilities for radiation terrorism and intensified concerns about nuclear accidents since the recent Fukushima Daiichi event, the potential exposure of large numbers of individuals to radiation that could lead to acute clinical effects has become a major concern. For the medical community to cope with such an event and avoid overwhelming the medical care system, it is essential to identify not only individuals who have received clinically significant exposures and need medical intervention but also those who do not need treatment. The ability of electron paramagnetic resonance to measure radiation-induced paramagnetic species, which persist in certain tissues (e.g., teeth, fingernails, toenails, bone, and hair), has led this technique to become a prominent method for screening significantly exposed individuals. Although the technical requirements needed to develop this method for effective application in a radiation event are daunting, remarkable progress has been made. In collaboration with General Electric, and through funding committed by the Biomedical Advanced Research and Development Authority, electron paramagnetic resonance tooth dosimetry of the upper incisors is being developed to become a Food and Drug Administration-approved and manufacturable device designed to carry out triage for a threshold dose of 2 Gy. Significant progress has also been made in the development of electron paramagnetic resonance nail dosimetry based on measurements of nails in situ under point-of-care conditions, and in the near future this may become a second field-ready technique. Based on recent progress in measurements of nail clippings, we anticipate that this technique may be implementable at remotely located laboratories to provide additional information when the measurements of dose on site need to be supplemented. We conclude that electron paramagnetic resonance dosimetry is likely to be a useful part of triage for a large-scale radiation incident. PMID:22850230

Swartz, Harold M.; Flood, Ann Barry; Williams, Benjamin B.; Dong, Ruhong; Swarts, Steven G.; He, Xiaoming; Grinberg, Oleg; Sidabras, Jason; Demidenko, Eugene; Gui, Jiang; Gladstone, David J.; Jarvis, Lesley A.; Kmiec, Maciej M.; Kobayashi, Kyo; Lesniewski, Piotr N.; Marsh, Stephen D.P.; Matthews, Thomas P.; Nicolalde, Roberto J.; Pennington, Patrick M.; Raynolds, Timothy; Salikhov, Ildar; Wilcox, Dean E.; Zaki, Bassem I.

2013-01-01

62

Electron paramagnetic resonance dosimetry for a large-scale radiation incident.  

PubMed

With possibilities for radiation terrorism and intensified concerns about nuclear accidents since the recent Fukushima Daiichi event, the potential exposure of large numbers of individuals to radiation that could lead to acute clinical effects has become a major concern. For the medical community to cope with such an event and avoid overwhelming the medical care system, it is essential to identify not only individuals who have received clinically significant exposures and need medical intervention but also those who do not need treatment. The ability of electron paramagnetic resonance to measure radiation-induced paramagnetic species, which persist in certain tissues (e.g., teeth, fingernails, toenails, bone, and hair), has led to this technique becoming a prominent method for screening significantly exposed individuals. Although the technical requirements needed to develop this method for effective application in a radiation event are daunting, remarkable progress has been made. In collaboration with General Electric and through funding committed by the Biomedical Advanced Research and Development Authority, electron paramagnetic resonance tooth dosimetry of the upper incisors is being developed to become a Food and Drug Administration-approved and manufacturable device designed to carry out triage for a threshold dose of 2 Gy. Significant progress has also been made in the development of electron paramagnetic resonance nail dosimetry based on measurements of nails in situ under point-of-care conditions, and in the near future this may become a second field-ready technique. Based on recent progress in measurements of nail clippings, it is anticipated that this technique may be implementable at remotely located laboratories to provide additional information when the measurements of dose on-site need to be supplemented. The authors conclude that electron paramagnetic resonance dosimetry is likely to be a useful part of triage for a large-scale radiation incident. PMID:22850230

Swartz, Harold M; Flood, Ann Barry; Williams, Benjamin B; Dong, Ruhong; Swarts, Steven G; He, Xiaoming; Grinberg, Oleg; Sidabras, Jason; Demidenko, Eugene; Gui, Jiang; Gladstone, David J; Jarvis, Lesley A; Kmiec, Maciej M; Kobayashi, Kyo; Lesniewski, Piotr N; Marsh, Stephen D P; Matthews, Thomas P; Nicolalde, Roberto J; Pennington, Patrick M; Raynolds, Timothy; Salikhov, Ildar; Wilcox, Dean E; Zaki, Bassem I

2012-09-01

63

Radiation-damage studies, irradiations and high-dose dosimetry for LHC detectors  

E-print Network

The proposal is divided into a main project and special projects. The main project consists of a service similar to the one given in the past to accelerator construction projects at CERN (ISR,SPS,LEP) on high-dose dosimetry, material irradiations, irradiations tests, standardization of test procedures and data compilations. Large experience in this field and numerous radiation damage test data of insulating and structural materials are available. The special projects cover three topics which are of specific interest for LHC detector physicists and engineers at CERN and in other high energy physics institutes, namely: Radiation effects in scintillators; Selection of radiation hard optical fibres for data transmission; and Selection and testing of radiation hard electronic components.

Coninckx, F; León-Florián, E; Leutz, H; Schönbacher, Helmut; Sonderegger, P; Tavlet, Marc; Sopko, B; Henschel, H; Schmidt, H U; Boden, A; Bräunig, D; Wulf, F; Cramariuc, R; Ilie, D; Fattibene, P; Onori, S; Miljanic, S; Paic, G; Razen, B; Razem, D; Rendic, D; CERN. Geneva. Detector Research and Development Committee

1991-01-01

64

Modeling radiation dosimetry to predict cognitive outcomes in pediatric patients with CNS embryonal tumors including medulloblastoma  

SciTech Connect

Purpose: Model the effects of radiation dosimetry on IQ among pediatric patients with central nervous system (CNS) tumors. Methods and Materials: Pediatric patients with CNS embryonal tumors (n = 39) were prospectively evaluated with serial cognitive testing, before and after treatment with postoperative, risk-adapted craniospinal irradiation (CSI) and conformal primary-site irradiation, followed by chemotherapy. Differential dose-volume data for 5 brain volumes (total brain, supratentorial brain, infratentorial brain, and left and right temporal lobes) were correlated with IQ after surgery and at follow-up by use of linear regression. Results: When the dose distribution was partitioned into 2 levels, both had a significantly negative effect on longitudinal IQ across all 5 brain volumes. When the dose distribution was partitioned into 3 levels (low, medium, and high), exposure to the supratentorial brain appeared to have the most significant impact. For most models, each Gy of exposure had a similar effect on IQ decline, regardless of dose level. Conclusions: Our results suggest that radiation dosimetry data from 5 brain volumes can be used to predict decline in longitudinal IQ. Despite measures to reduce radiation dose and treatment volume, the volume that receives the highest dose continues to have the greatest effect, which supports current volume-reduction efforts.

Merchant, Thomas E. [Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States)]. E-mail: thomas.merchant@stjude.org; Kiehna, Erin N. [Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Li Chenghong [Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN (United States); Shukla, Hemant [Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Sengupta, Saikat [Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Xiong Xiaoping [Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN (United States); Gajjar, Amar [Department of Hematology Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Mulhern, Raymond K. [Division of Behavioral Medicine, St. Jude Children's Research Hospital, Memphis, TN (United States)

2006-05-01

65

Radiation dosimetry data management using VAX C, FMS, RMS, DCL, and Oracle  

Microsoft Academic Search

The External Dosimetry Badge System was developed to support the radiation protection program at Los Alamos National Laboratory. The radiation protection program is responsible for monitoring external radiation exposures to approximately 7,500 Laboratory employees, visitors and contractors each month. External radiation exposure is measured using thermoluminescent dosimeters (TLDs). The system is used to control the assembly and distribution of TLD

M. J. Jr. Voltin; A. K. Martin

1991-01-01

66

Radiation dosimetry onboard the International Space Station ISS  

Microsoft Academic Search

Besides the effects of the microgravity environment, and the psychological and psychosocial problems encountered in confined spaces, radiation is the main health detriment for long duration human space missions. The radiation environment encountered in space differs in nature from that on earth, consisting mostly of high energetic ions from protons up to iron, resulting in radiation levels far exceeding the

Thomas Berger

2008-01-01

67

Genetic and molecular dosimetry of HZE radiation (US-1 RADIAT)  

NASA Technical Reports Server (NTRS)

In order to estimate radiation exposure in space, experiments were conducted during the 1st International Microgravity Laboratory (IML-1) mission in order to isolate genetic changes in animal cells caused by cosmic rays. The space measurements were evaluated against results from synthetic cosmic rays produced by particle accelerators on the ground. The biological material used was the tiny soil nematode, Caenorhabditis elegans. The measurements were made by thermoluminescent detectors and plastic nuclear track detectors. The development and the chromosome mechanics in microgravity were studied, and the mutagenesis induced by radiation exposure was analyzed. The results showed that there are no obvious differences in the development, behavior and chromosome mechanics, as a function of gravity unloading (reproduction, self-fertilization and mating of males with hermaphrodites, gross anatomy, symmetry and gametogenesis, pairing, disjoining and recombination of chromosomes). A variety of mutants were isolated, and it was noted that mutants isolated from regions of identified high particles were more severely affected than those isolated by random screening. Linear energy transfer particles seem to favor large scale genetic lesions.

Nelson, Gregory A.; Schubert, W. W.; Kazarians, G. A.; Richards, G. F.; Benton, E. V.; Benton, E. R.; Henke, R. P.

1995-01-01

68

Radiation Protection Dosimetry Vol. 97, No. 3, pp. 279-285 (2001)  

E-print Network

1 Radiation Protection Dosimetry Vol. 97, No. 3, pp. 279-285 (2001) Nuclear Technology Publishing Topics under Debate IS THE LINEAR-NO-THRESHOLD HYPOTHESIS APPROPRIATE FOR USE IN RADIATION PROTECTION? D. C. McDonald, Moderator INTRODUCTION There are few things more important to the practice of radiation

Brenner, David Jonathan

69

GENII (Generation II): The Hanford Environmental Radiation Dosimetry Software System: Volume 3, Code maintenance manual: Hanford Environmental Dosimetry Upgrade Project  

SciTech Connect

The Hanford Environmental Dosimetry Upgrade Project was undertaken to incorporate the internal dosimetry models recommended by the International Commission on Radiological Protection (ICRP) in updated versions of the environmental pathway analysis models used at Hanford. The resulting second generation of Hanford environmental dosimetry computer codes is compiled in the Hanford Environmental Dosimetry System (Generation II, or GENII). This coupled system of computer codes is intended for analysis of environmental contamination resulting from acute or chronic releases to, or initial contamination of, air, water, or soil, on through the calculation of radiation doses to individuals or populations. GENII is described in three volumes of documentation. This volume is a Code Maintenance Manual for the serious user, including code logic diagrams, global dictionary, worksheets to assist with hand calculations, and listings of the code and its associated data libraries. The first volume describes the theoretical considerations of the system. The second volume is a Users' Manual, providing code structure, users' instructions, required system configurations, and QA-related topics. 7 figs., 5 tabs.

Napier, B.A.; Peloquin, R.A.; Strenge, D.L.; Ramsdell, J.V.

1988-09-01

70

Intrinsic Dosimetry: Elemental Composition Effects on the Thermoluminescence of Commercial Borosilicate Glass  

SciTech Connect

Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering this dose in tandem with the physical characteristics of the radioactive material housed within the container, this method can provide enhanced pathway information for interdicted radioactive samples. Thermoluminescence (TL) dosimetry was used to measure ionizing radiation dose effects on stock borosilicate glass. Differences in TL glow curve shape and intensity were observed for glasses from different geographical origins. The different TL signatures strongly correlated with the concentration of alkaline earth metals and the ratio of sodium to the total amount of alkali metal present in the borosilicate glass.

Richard A. Clark; J. David Robertson; Jon M. Schwantes

2013-12-01

71

Intrinsic Dosimetry: Elemental Composition Effects on the Thermoluminescence of Commercial Borosilicate Glass  

SciTech Connect

Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering this dose in tandem with the physical characteristics of the radioactive material housed within the container, this method can provide enhanced pathway information for interdicted radioactive samples. Thermoluminescence (TL) dosimetry was used to measure ionizing radiation dose effects on stock borosilicate glass. Differences in TL glow curve shape and intensity were observed for glasses from different geographical origins. The different TL signatures strongly correlated with the concentration of alkaline earth metals and the ratio of sodium to the total amount of alkali metal present in the borosilicate glass.

Clark, Richard A.; Robinson, J. D.; Schwantes, Jon M.

2013-12-07

72

Effects of dose fractionation on the response of alanine dosimetry  

NASA Astrophysics Data System (ADS)

Alanine dosimetry is well established as a transfer standard and is becoming more prevalently used in routine dosimetry systems for radiation processing. Many routine measurement applications in radiation processing involve absorbed dose measurements resulting from fractioned exposures to ionizing radiation. Fractioning of absorbed dose is identified as an influence quantity (ISO/ASTM, 2013). This paper reports on study results of absorbed dose fractioning characteristics of alanine for gamma and high energy electron beam radiation sources. The results of this study indicate a radiation response difference due to absorbed dose fractioning in response can be observed after four fractionations for high-energy electron beams and no difference up to seven fractions for gamma rays using an ANOVA evaluation method.

Lundahl, Brad; Logar, John; Desrosiers, Marc; Puhl, James

2014-12-01

73

Workshop report on atomic bomb dosimetry-residual radiation exposure: recent research and suggestions for future studies.  

PubMed

There is a need for accurate dosimetry for studies of health effects in the Japanese atomic bomb survivors because of the important role that these studies play in worldwide radiation protection standards. International experts have developed dosimetry systems, such as the Dosimetry System 2002 (DS02), which assess the initial radiation exposure to gamma rays and neutrons but only briefly consider the possibility of some minimal contribution to the total body dose by residual radiation exposure. In recognition of the need for an up-to-date review of the topic of residual radiation exposure in Hiroshima and Nagasaki, recently reported studies were reviewed at a technical session at the 57th Annual Meeting of the Health Physics Society in Sacramento, California, 22-26 July 2012. A one-day workshop was also held to provide time for detailed discussion of these newer studies and to evaluate their potential use in clarifying the residual radiation exposures to the atomic-bomb survivors at Hiroshima and Nagasaki. Suggestions for possible future studies are also included in this workshop report. PMID:23799498

Kerr, George D; Egbert, Stephen D; Al-Nabulsi, Isaf; Beck, Harold L; Cullings, Harry M; Endo, Satoru; Hoshi, Masaharu; Imanaka, Tetsuji; Kaul, Dean C; Maruyama, Satoshi; Reeves, Glen I; Ruehm, Werner; Sakaguchi, Aya; Simon, Steven L; Spriggs, Gregory D; Stram, Daniel O; Tonda, Tetsuji; Weiss, Joseph F; Weitz, Ronald L; Young, Robert W

2013-08-01

74

Workshop Report on Atomic Bomb Dosimetry--Residual Radiation Exposure: Recent Research and Suggestions for Future Studies  

SciTech Connect

There is a need for accurate dosimetry for studies of health effects in the Japanese atomic bomb survivors because of the important role that these studies play in worldwide radiation protection standards. International experts have developed dosimetry systems, such as the Dosimetry System 2002 (DS02), which assess the initial radiation exposure to gamma rays and neutrons but only briefly consider the possibility of some minimal contribution to the total body dose by residual radiation exposure. In recognition of the need for an up-to-date review of the topic of residual radiation exposure in Hiroshima and Nagasaki, recently reported studies were reviewed at a technical session at the 57th Annual Meeting of the Health Physics Society in Sacramento, California, 22-26 July 2012. A one-day workshop was also held to provide time for detailed discussion of these newer studies and to evaluate their potential use in clarifying the residual radiation exposures to the atomic-bomb survivors at Hiroshima and Nagasaki. Suggestions for possible future studies are also included in this workshop report.

none,

2013-06-06

75

Developing a high performance superoxide dismutase based electrochemical biosensor for radiation dosimetry of thallium 201  

NASA Astrophysics Data System (ADS)

To develop a new biosensor for measurement of superoxide free radical generated in radiolysis reaction, three combinations of SOD-based biosensors including Au/Cys/SOD, Au/GNP/Cys/SOD and Au/GNP/Cys/SOD/Chit were fabricated. In these biosensors Au, GNP, Cys, SOD and Chit represent gold electrode, gold nano-particles, cysteine, superoxide dismutase and chitosan, respectively. For biosensors fabrication, SOD, GNP, Cys and Chit were immobilized at the surface of gold electrode. Cyclic voltametry and chronoamperometry were utilized for evaluation of biosensors performances. The results showed that Au/GNP/Cys/SOD/Chit has significantly better responses compared to Au/Cys/SOD and Au/GNP/Cys/SOD. As a result, this biosensor was selected for dosimetry of ionizing radiation. For this purpose, thallium 201 at different volumes was added to buffer phosphate solution in electrochemical cell. To obtain analytical parameters of Au/GNP/Cys/SOD/Chit, calibration curve was sketched. The results showed that this biosensor has a linear response in the range from 0.5 to 4 Gy, detection limit 0.03 ?M. It also has a proper sensitivity (0.6038 nA/Gy), suitable long term stability and cost effective as well as high function for radiation dosimetry.

Salem, Fatemeh; Tavakoli, Hassan; Sadeghi, Mahdi; Riazi, Abbas

2014-09-01

76

Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry  

SciTech Connect

Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KCl:Eu{sup 2+}), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. Methods: Pellet-style KCl:Eu{sup 2+} dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate {sup 137}Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu{sup 2+}, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. Results: KCl:Eu{sup 2+} dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100-700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0-5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. Conclusions: Systematic studies of KCl:Eu{sup 2+} material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu{sup 2+} exhibits strong radiation hardness and lends support for further investigations of this novel material.

Driewer, Joseph P.; Chen, Haijian; Osvet, Andres; Low, Daniel A.; Li, H. Harold [Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 and Nuclear Science and Engineering Institute, University of Missouri, E4431 Lafferre Hall, Columbia, Missouri 65211 (United States); Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States); Department of Materials Science and Engineering, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, Erlangen 91058 (Germany); Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States)

2011-08-15

77

Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry  

PubMed Central

Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KCl:Eu2+), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. Methods: Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate 137Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu2+, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. Results: KCl:Eu2+ dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100–700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0–5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. Conclusions: Systematic studies of KCl:Eu2+ material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu2+ exhibits strong radiation hardness and lends support for further investigations of this novel material. PMID:21928642

Driewer, Joseph P.; Chen, Haijian; Osvet, Andres; Low, Daniel A.; Li, H. Harold

2011-01-01

78

International Standardization of the Clinical Dosimetry of Beta Radiation Brachytherapy Sources: Progress of an ISO Standard  

NASA Astrophysics Data System (ADS)

In 2004 a new work item proposal (NWIP) was accepted by the International Organization for Standardization (ISO) Technical Committee 85 (TC85 -- Nuclear Energy), Subcommittee 2 (Radiation Protection) for the development of a standard for the clinical dosimetry of beta radiation sources used for brachytherapy. To develop this standard, a new Working Group (WG 22 - Ionizing Radiation Dosimetry and Protocols in Medical Applications) was formed. The standard is based on the work of an ad-hoc working group initiated by the Dosimetry task group of the Deutsches Insitiut für Normung (DIN). Initially the work was geared mainly towards the needs of intravascular brachytherapy, but with the decline of this application, more focus has been placed on the challenges of accurate dosimetry for the concave eye plaques used to treat ocular melanoma. Guidance is given for dosimetry formalisms, reference data to be used, calibrations, measurement methods, modeling, uncertainty determinations, treatment planning and reporting, and clinical quality control. The document is currently undergoing review by the ISO member bodies for acceptance as a Committee Draft (CD) with publication of the final standard expected by 2007. There are opportunities for other ISO standards for medical dosimetry within the framework of WG22.

Soares, Christopher

2006-03-01

79

Dosimetry by means of the radiation reduction of hemin in aprotic solvents. Final report  

SciTech Connect

Iron (III) porphyrins when dissolved in certain polar organic solvents are reduced by ionizing radiation. This results in a stable shift of both the Soret (B) and visible (Q) absorption bands, as long as the solution is maintained in a deaerated state, thus affording a means of radiation dosimetry.

McLaughlin, W.L.; Simic, M.G.; Miller, A.

1982-01-01

80

Human Brain Imaging and Radiation Dosimetry of 11C-N-Desmethyl-Loperamide,  

E-print Network

- tion of radioactivity in the entire body to estimate radiation expo- sure. Methods: Brain PET scans- compartment model to estimate the rate of entry (K1) of radio- tracer into the brain. Whole-body PET scansHuman Brain Imaging and Radiation Dosimetry of 11C-N-Desmethyl-Loperamide, a PET Radiotracer

Shen, Jun

81

Optical filtering and spectral measurements of radiation-induced light in plastic scintillation dosimetry  

Microsoft Academic Search

A small, water-equivalent plastic scintillation detector system has previously been developed for radiation therapy dosimetry. A light signal, proportional to dose, is generated in the scintillator and is transmitted to a remote photomultiplier tube (PMT) via optical fibres. Ionizing radiation also produces light in the fibres, which, if not properly accounted for, could limit the accuracy of the scintillator system.

S. F. de Boer; A. S. Beddar; J. A. Rawlinson

1993-01-01

82

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+  

PubMed Central

This work, for the first time, reports the use of europium doped potassium chloride (KCl:Eu2+) storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl:Eu2+ functions using the same photostimulatated luminescence (PSL) mechanism as commercially available BaFBr0.85I0.15:Eu2+ material that is used for computed radiography (CR) but features a significantly smaller effective atomic number—18 versus 49—making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl:Eu2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within ±2.5%. The findings were (1) KCl:Eu2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. (2) KCl:Eu2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. (3) After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1%?h after 12 h. (4) The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy?min. (5) The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. (6) Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters (0.3 mm thick lead foils) during irradiation, the over-response was reduced. The authors have demonstrated that KCl:Eu2+ dosimeters have many desirable dosimetric characteristics that make the material conducive to radiation therapy dosimetry. In the future, a large-area KCl:Eu2+-based CR plate with a thickness of the order of a few microns, created using modern thin film techniques, could provide a reusable, quantitative, high-resolution two-dimensional dosimeter with minimal energy dependence. PMID:19746808

Han, Zhaohui; Driewer, Joseph P.; Zheng, Yuanshui; Low, Daniel A.; Li, H. Harold

2009-01-01

83

Radiation dosimetry predicts IQ after conformal radiation therapy in pediatric patients with localized ependymoma  

SciTech Connect

Purpose: To assess the effects of radiation dose-volume distribution on the trajectory of IQ development after conformal radiation therapy (CRT) in pediatric patients with ependymoma. Methods and Materials: The study included 88 patients (median age, 2.8 years {+-} 4.5 years) with localized ependymoma who received CRT (54-59.4 Gy) that used a 1-cm margin on the postoperative tumor bed. Patients were evaluated with tests that included IQ measures at baseline (before CRT) and at 6, 12, 24, 36, 48, and 60 months. Differential dose-volume histograms (DVH) were derived for total-brain, supratentorial-brain, and right and left temporal-lobe volumes. The data were partitioned into three dose intervals and integrated to create variables that represent the fractional volume that received dose over the specified intervals (e.g., V{sub 0-20Gy}, V{sub 20-40Gy}, V{sub 40-65Gy}) and modeled with clinical variables to develop a regression equation to estimate IQ after CRT. Results: A total of 327 IQ tests were performed in 66 patients with infratentorial tumors and 20 with supratentorial tumors. The median follow-up was 29.4 months. For all patients, IQ was best estimated by age (years) at CRT; percent volume of the supratentorial brain that received doses between 0 and 20 Gy, 20 and 40 Gy, and 40 and 65 Gy; and time (months) after CRT. Age contributed significantly to the intercept (p > 0.0001), and the dose-volume coefficients were statistically significant (V{sub 0-20Gy}, p = 0.01; V{sub 20-40Gy}, p < 0.001; V{sub 40-65Gy}, p = 0.04). A similar model was developed exclusively for patients with infratentorial tumors but not supratentorial tumors. Conclusion: Radiation dosimetry can be used to predict IQ after CRT in patients with localized ependymoma. The specificity of models may be enhanced by grouping according to tumor location.

Merchant, Thomas E. [Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States)]. E-mail: thomas.merchant@stjude.org; Kiehna, Erin N. [Division of Radiation Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Li Chenghong [Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN (United States); Xiong Xiaoping [Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN (United States); Mulhern, Raymond K. [Division of Behavioral Medicine, St. Jude Children's Research Hospital, Memphis, TN (United States)

2005-12-01

84

Internal radiation dosimetry of orally administered radiotracers for the assessment of gastrointestinal motility.  

PubMed

Radionuclide imaging using (111)In, (99m)Tc and (153)Sm is commonly undertaken for the clinical investigation of gastric emptying, intestinal motility and whole gut transit. However the documented evidence concerning internal radiation dosimetry for such studies is not readily available. This communication documents the internal radiation dosimetry for whole gastrointestinal transit studies using (111)In, (99m)Tc and (153)Sm labeled formulations. The findings were compared to the diagnostic reference levels recommended by the United Kingdom Administration of Radioactive Substances Advisory Committee, for gastrointestinal transit studies. PMID:25222875

Yeong, Chai-Hong; Ng, Kwan-Hoong; Abdullah, Basri Johan Jeet; Chung, Lip-Yong; Goh, Khean-Lee; Perkins, Alan Christopher

2014-12-01

85

The Application of FLUKA to Dosimetry and Radiation Therapy  

NASA Technical Reports Server (NTRS)

Monte Carlo transport codes like FLUKA are useful for many purposes, and one of those is the simulation of the effects of radiation traversing the human body. In particular, radiation has been used in cancer therapy for a long time, and recently this has been extended to include heavy ion particle beams. The advent of this particular type of therapy has led to the need for increased capabilities in the transport codes used to simulate the detailed nature of the treatment doses to the Y O U S tissues that are encountered. This capability is also of interest to NASA because of the nature of the radiation environment in space.[l] While in space, the crew members bodies are continually being traversed by virtually all forms of radiation. In assessing the risk that this exposure causes, heavy ions are of primary importance. These arise both from the primary external space radiation itself, as well as fragments that result from interactions during the traversal of that radiation through any intervening material including intervening body tissue itself. Thus the capability to characterize the details of the radiation field accurately within a human body subjected to such external 'beams" is of critical importance.

Wilson, Thomas L.; Andersen, Victor; Pinsky, Lawrence; Ferrari, Alfredo; Battistoni, Giusenni

2005-01-01

86

The role of Monte Carlo simulation of electron transport in radiation dosimetry.  

PubMed

A brief overview is given of the role in radiation dosimetry of electron transport simulations using the Monte Carlo technique. Two areas are discussed in some detail. The first is the calculation of stopping-power ratios for use in ion chamber dosimetry. The uncertainty in stopping-power ratios is discussed with attention being drawn to the fact that the relative uncertainty in restricted collision stopping powers is greater than that in unrestricted stopping powers if the major source of uncertainty is the density effect correction. Using ICRU Report 37 stopping powers and electron spectra calculated in a small cylinder of graphite, the value of the Spencer-Attix graphite to air stopping-power ratio in a 60Co beam is found to be 1.0021 for an assumed graphite density of 1.70 g/cm(3) and 0.23% less for an assumed density of 2.26 g/cm(3). The second area discussed is the feasibility of using Monte Carlo techniques to calculate dose patterns in a patient undergoing electron beam radiotherapy. PMID:1661717

Rogers, D W

1991-01-01

87

Statistical issues in biological radiation dosimetry for risk assessment using stable chromosome aberrations  

SciTech Connect

Biological dosimeters are useful for epidemiologic risk assessment in populations exposed to catastrophic nuclear events and as a means of validating physical dosimetry in radiation workers. Application requires knowledge of the magnitude of uncertainty in the biological dose estimates and an understanding of potential statistical pitfalls arising from their use. This paper describes the statistical aspects of biological dosimetry in general and presents a detailed analysis in the specific case of dosimetry for risk assessment using stable chromosome aberration frequency. Biological dose estimates may be obtained from a dose-response curve, but negative estimates can result and adjustment must be made for regression bias due to imprecise estimation when the estimates are used in regression analyses. Posterior-mean estimates, derived as the mean of the distribution of true doses compatible with a given value of the biological endpoint, have several desirable properties: they are nonnegative, less sensitive to extreme skewness in the true dose distribution, and implicitly adjusted to avoid regression bias. The methods necessitate approximating the true-dose distribution in the population in which biological dosimetry is being applied, which calls for careful consideration of this distribution through other information. An important question addressed here is to what extent the methods are robust to misspecification of this distribution, because in many applications of biological dosimetry it cannot be characterized well. The findings suggest that dosimetry based solely on stable chromosome aberration frequency may be useful for population-based risk assessment.

Cologne, J.B.; Preston, D.L. [Radiation Effects Research Foundation, Hiroshima (Japan). Dept. of Statistics; Pawel, D.J. [Environmental Protection Agency, Washington, DC (United States)

1998-11-01

88

Radiation Protection Dosimetry Vol. 84, Nos. 14, pp. 131133 (1999)  

E-print Network

by vacuum UV (VUV) radiation(3) . In the present work the photo- transferred thermoluminescence (PTTL) of Ca on the tem- perature was measured between LNT and RT. Effects of optical and thermal bleaching as well as the dose dependences of the PTTL intensities were also investi- gated. EXPERIMENTAL PROCEDURE The nominally

Chen, Reuven

89

Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry  

Microsoft Academic Search

Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417nm depends linearly on the dose below 50kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed.

Munzer Kattan; Haroun al Kassiri; Yarob Daher

2011-01-01

90

Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry.  

PubMed

Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417 nm depends linearly on the dose below 50 kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed. PMID:21109445

Kattan, Munzer; al Kassiri, Haroun; Daher, Yarob

2011-02-01

91

The impact of MLC transmitted radiation on EPID dosimetry for dynamic MLC beams  

SciTech Connect

The purpose of this study was to experimentally quantify the change in response of an amorphous silicon (a-Si) electronic portal imaging device (EPID) to dynamic multileaf collimator (dMLC) beams with varying MLC-transmitted dose components and incorporate the response into a commercial treatment planning system (TPS) EPID prediction model. A combination of uniform intensity dMLC beams and static beams were designed to quantify the effect of MLC transmission on EPID response at the central axis of 10x10 cm{sup 2} beams, at off-axis positions using wide dMLC beam profiles, and at different field sizes. The EPID response to MLC transmitted radiation was 0.79{+-}0.02 of the response to open beam radiation at the central axis of a 10x10 cm{sup 2} field. The EPID response to MLC transmitted radiation was further reduced relative to the open beam response with off-axis distance. The EPID response was more sensitive to field size changes for MLC transmitted radiation compared to open beam radiation by a factor of up to 1.17 at large field sizes. The results were used to create EPID response correction factors as a function of the fraction of MLC transmitted radiation, off-axis distance, and field size. Software was developed to apply the correction factors to each pixel in the TPS predicted EPID image. The corrected images agreed more closely with the measured EPID images in areas of intensity modulated fields with a large fraction of MLC transmission and, as a result the accuracy of portal dosimetry with a-Si EPIDs can be improved. Further investigation into the detector response function and the radiation source model are required to achieve improvements in accuracy for the general case.

Vial, Philip; Greer, Peter B.; Hunt, Peter; Oliver, Lyn; Baldock, Clive [Royal North Shore Hospital, Sydney (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney (Australia) and Department of Radiation Oncology, Liverpool Hospital, Sydney (Australia); Calvary Mater Newcastle Hospital, Newcastle, Australia and University of Newcastle, Newcastle (Australia); Royal North Shore Hospital, Sydney (Australia); Royal North Shore Hospital, Sydney (Australia) and Institute of Medical Physics, School of Physics, University of Sydney, Sydney (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney (Australia)

2008-04-15

92

The PUR Experiment on the EXPOSE-R facility: biological dosimetry of solar extraterrestrial UV radiation  

NASA Astrophysics Data System (ADS)

The aim of our experiment Phage and Uracil Response was to extend the use of bacteriophage T7 and uracil biological dosimeters for measuring the biologically effective ultraviolet (UV) dose in the harsh extraterrestrial radiation conditions. The biological detectors were exposed in vacuum-tightly cases in the European Space Agency (ESA) astrobiological exposure facility attached to the external platform of Zvezda (EXPOSE-R). EXPOSE-R took off to the International Space Station (ISS) in November 2008 and was installed on the External platform of the Russian module Zvezda of the ISS in March 2009. Our goal was to determine the dose-effect relation for the formation of photoproducts (i.e. damage to phage DNA and uracil, respectively). The extraterrestrial solar UV radiation ranges over the whole spectrum from vacuum-UV (?<200 nm) to UVA (315 nmradiation. From this aspect the role of the photoreversion in the extension of the biological UV dosimetry are discussed.

Bérces, A.; Egyeki, M.; Fekete, A.; Horneck, G.; Kovács, G.; Panitz, C.

2015-01-01

93

Dosimetry of Atomic Bomb Radiation in Hiroshima by Thermoluminescence of Roof Tiles  

Microsoft Academic Search

Thermoluminescence dosimetry is a powerful tool for obtaining the distribution of gamma dose, heretofore unknown, from the atomic bombs dropped on Hiroshima and Nagasaki. Roof tiles irradiated by the bombs show intense thermoluminescence, and the radiation dose for samples irradiated below 100 r by the bomb can be measured by this method.

Takenobu Higashimura; Yoneta Ichikawa; Tunahiko Sidei

1963-01-01

94

Verification of intensity modulated radiation therapy beams using a tissue equivalent plastic scintillator dosimetry system  

Microsoft Academic Search

This thesis describes the development and implementation of a novel method for the dosimetric verification of intensity modulated radiation therapy (IMRT) fields with several advantages over current techniques. Through the use of a tissue equivalent plastic scintillator sheet viewed by a charge-coupled device (CCD) camera, this method provides a truly tissue equivalent dosimetry system capable of efficiently and accurately performing

Martin Peter Petric

2006-01-01

95

Radiochromic film dosimetry: Recommendations of AAPM Radiation Therapy Committee Task Group 55  

Microsoft Academic Search

Recommendations of the American Association of Physicists in Medicine (AAPM) for the radio- chromic film dosimetry are presented. These guidelines were prepared by a task group of the AAPM Radiation Therapy Committee and have been reviewed and approved by the AAPM Science Council. © 1998 American Association of Physicists in Medicine. (S0094-2405(98)00211-9)

Azam Niroomand-Rad; Charles Robert Blackwell; Bert M. Coursey; Kenneth P. Gall; James M. Galvin; William L. McLaughlin; Ali S. Meigooni; Ravinder Nath; James E. Rodgers; Christopher G. Soares

1998-01-01

96

Impact of Track Structure Effects on Shielding and Dosimetry  

NASA Technical Reports Server (NTRS)

Galactic cosmic rays (GCR) consisting of nuclei of all the known elements with kinetic energies extending from tens to millions of MeV pose a significant health hazard to future deep space operations. Even half of the radiation exposures expected in ISS will result from GCR components. The biological actions of these radiations are known to depend on the details of the energy deposition (not just linear energy transfer, LET, but the lateral dispersion of energy deposition about the particle track). Energy deposits in tissues are dominated by the transfer of tens to hundreds of eV to the tissue's atomic electrons. In the case of low LET radiations, the collisions are separated by large dimensions compared to the size of important biomolecular structures. If such events are also separated in time, then the radiation adds little to the background of radicals occurring from ordinary metabolic processes and causes little or no biological injury. Hence, dose rate is a strong determinant of the action of low LET exposures. The GCR exposures are dominated by ions of high charge and energy (HZE) characterized by many collisions with atomic electrons over biomolecular dimensions, resulting in high radical- density events associated with a few isolated ion paths through the cell and minimal dose rate dependence at ordinary exposure levels. The HZE energy deposit declines quickly laterally and merges with the background radical density in the track periphery for which the exact lateral distribution of the energy deposit is the determinant of the biological injury. Although little data exists on human exposures from HZE radiations, limited studies in mice and mammalian cell cultures allow evaluation of the effects of track structure on shield attenuation properties and evaluation of implications for dosimetry. The most complete mammalian cell HZE exposure data sets have been modeled including the C3H10T1/2 survival and transformation data of Yang et al., the V79 survival and mutation data of various groups, and the Harderian gland tumor data of Alpen et al. Model results for the Harderian gland tumor data in comparison with data from Alpen et al. The Harderian target cell initiation cross section compares closely with the transformation cross section found for the C3H10T1/2 cell transformation data of Yang et al. The most notable feature of the cross sections are the multivalued cross sections for a given LET which implies the corresponding relative biological effectiveness (RBE) is dependent not only on the LET but also the ion type. This fact is at variance with the latest ICRP recommended quality factor which is a defined function of only the LET.

Wilson, J. W.; Cucinotta, F. A.; Schimmerling, W.; Kim, M. Y.

1999-01-01

97

Photon dosimetry using plastic scintillators in pulsed radiation fields  

SciTech Connect

Simulations and experiments have been carried out to explore using a plastic scintillator as a dosimetry probe in the vicinity of a pulsed bremsstrahlung source in the range 4 to 20 MeV. Taking advantage of the tissue-equivalent properties of this detector in conjunction with the use of a fast digital signal processor near real-time dosimetry was shown to be possible. The importance of accounting for a broad energy electron beam in bremsstrahlung production, and photon scattering and build-up, in correctly interpreting dosimetry results at long stand-off distances is highlighted by comparing real world experiments with ideal geometry simulations. Close agreement was found between absorbed energy calculations based upon spectroscopic techniques and calculations based upon signal integration, showing a ratio between 10 MeV absorbed dose to 12 MeV absorbed dose of 0.66 at a distance of 91.4 m from the accelerator. This is compared with an idealized model simulation with a monoenergetic electron beam and without scattering, where the ratio was 0.46.

David L. Chichester; Brandon W. Blackburn; James T. Johnson; Scott W. Watson

2007-04-01

98

Micro-Fabricated Solid-State Radiation Detectors for Active Personal Dosimetry  

NASA Technical Reports Server (NTRS)

Active radiation dosimetry is important to human health and equipment functionality for space applications outside the protective environment of a space station or vehicle. This is especially true for long duration missions to the moon, where the lack of a magnetic field offers no protection from space radiation to those on extravehicular activities. In order to improve functionality, durability and reliability of radiation dosimeters for future NASA lunar missions, single crystal silicon carbide devices and scintillating fiber detectors are currently being investigated for applications in advanced extravehicular systems. For many years, NASA Glenn Research Center has led significant efforts in silicon carbide semiconductor technology research and instrumentation research for sensor applications under extreme conditions. This report summarizes the technical progress and accomplishments toward characterization of radiation-sensing components for the recommendation of their fitness for advanced dosimetry development.

Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.; Chen, Liang-Yu

2007-01-01

99

PREFACE: 7th International Conference on 3D Radiation Dosimetry (IC3DDose)  

NASA Astrophysics Data System (ADS)

IC3DDose 2013, the 7th International Conference on 3D Radiation Dosimetry held in Sydney, Australia from 4-8 November 2012, grew out of the DosGel series, which began as DosGel99, the 1st International Workshop on Radiation Therapy Gel Dosimetry in Lexington, Kentucky. Since 1999 subsequent DoSGel conferences were held in Brisbane, Australia (2001), Ghent, Belgium (2004), Sherbrooke, Canada (2006) and Crete, Greece (2008). In 2010 the conference was held on Hilton Head Island, South Carolina and underwent a name-change to IC3DDose. The aim of the first workshop was to bring together individuals, both researchers and users, with an interest in 3D radiation dosimetry techniques, with a mix of presentations from basic science to clinical applications, which has remained an objective for all of the meetings. One rationale of DosGel99 was stated as supporting the increasing clinical implementation of gel dosimetry, as the technique appeared, at that time, to be leaving the laboratories of gel dosimetry enthusiasts and entering clinical practice. Clearly by labelling the first workshop as the 1st, there was a vision of a continuing series, which has been fulfilled. On the other hand, the expectation of widespread clinical use of gel dosimetry has perhaps not been what was hoped for and anticipated. Nevertheless the rapidly increasing demand for advanced high-precision 3D radiotherapy technology and techniques has continued apace. The need for practical and accurate 3D dosimetry methods for development and quality assurance has only increased. By the 6th meeting, held in South Carolina in 2010, the Conference Scientific Committee recognised the wider developments in 3D systems and methods and decided to widen the scope, whilst keeping the same span from basic science to applications. This was signalled by a change of name from 'Dosgel' to 'IC3DDose', a name that has continued to this latest conference. The conference objectives were: to enhance the quality and accuracy of radiation therapy treatment through improved clinical dosimetry to investigate and understand the dosimetric challenges of modern radiation treatments to provide a forum to discuss the latest research and developments in 3D and advanced radiation dosimetry to energise and diversify dosimetry research and clinical practice by encouraging interaction and synergy between advanced, 3D and semi-3D dosimetry techniques We believe the conference program, with its excellent range of expert and specialist speakers, met these objectives. Thanks are due to all invited speakers for their participation, to the Local Organising Committee members for all their hard work in making the conference happen, particularly the small core administrative support group, and to the range of academic, organisation and commercial sponsors who generously supported the meeting. The Scientific Committee members are also thanked for reviewing the submitted manuscripts and for assisting in the editorial process. Finally, all who travelled to Sydney, Australia for the meeting are acknowledged for choosing to attend and contribute to making this a successful conference. Local Conference Organising Committee David Thwaites (Conference Convener) Clive Baldock Leanne Price Elizabeth Starkey May Whitaker Peter Greer Lois Holloway Phil Vial Robin Hill Conference Scientific Committee Sven Back (Sweden) Clive Baldock (Australia) Cheng-Shie Wuu (USA) Yves de Deene (Belgium) Simon Doran (UK) Geoffrey Ibbott (USA) Andrew Jirasek (Canada) Kevin Jordan (Canada) Martin Lepage (Canada) Mark Oldham (USA) Evangelos Pappas (Greece) John Schreiner (Canada) David Thwaites (Australia) David ThwaitesClive Baldock DirectorExecutive Dean Institute of Medical PhysicsFaculty of Science School of PhysicsMacquarie University University of SydneyNorth Ryde NSW 2006NSW 2109 AustraliaAustralia The PDF also contains the conference program.

Thwaites, David; Baldock, Clive

2013-06-01

100

Review of the correlation between results of cytogenetic dosimetry from blood lymphocytes and EPR dosimetry from tooth enamel for victims of radiation accidents.  

PubMed

The goal of this study was to compare dose estimates from electron paramagnetic resonance (EPR) dosimetry with teeth and cytogenetic dosimetry with blood lymphocytes for 30 victims of radiation accidents. The whole-body exposures estimated by tooth enamel EPR dosimetry were ranging from 0.01 to 9.3 Gy. Study group comprised victims exposed to acute and prolonged irradiation at high and low dose rate in different accidents. Blood samples were taken from each of them for cytogenetic analysis. Aberrations were scored and analysed according to International Atomic Energy Agency (IAEA) guidelines for conventional and FISH analysis. Tooth samples were collected in dental clinics after they had been extracted during ordinary practice. EPR dosimetry was performed according to the IAEA protocol. EPR dosimetry showed good correlation with dosimetry based on chromosomal analysis. All estimations of cytogenetic dose below detection limit coincide with EPR dose estimates within the ranges of uncertainty. The differences between cytogenetic and EPR assays may occur in a case of previous unaccounted exposure, non-homogeneous irradiation and due to contribution to absorbed dose from neutron irradiation. PMID:24982260

Khvostunov, I K; Ivannikov, A I; Skvortsov, V G; Nugis, V Yu; Golub, E V

2015-03-01

101

High field magnetic resonance imaging-based gel dosimetry for small radiation fields  

NASA Astrophysics Data System (ADS)

Small megavoltage photon radiation fields (< 3cm diameter) are used in advanced radiation therapy techniques, such as intensity modulated radiotherapy, and stereotactic radiosurgery, as well as for cellular and preclinical radiobiology studies (very small fields, <1 mm diameter). Radiation dose characteristics for these small fields are difficult to determine in multiple dimensions because of steep dose gradients (30--40% per mm) and conditions of electronic disequilibrium. Conventional radiation dosimetry techniques have limitations for small fields because detector size may be large compared to radiation field size and/or dose acquisition may be restricted to one or two dimensions. Polymer gel dosimetry, is a three-dimensional (3D) dosimeter based on radiation-induced polymerization of tissue equivalent gelatin. Polymer gel dosimeters can be read using magnetic resonance imaging (MRI), which detects changes in relaxivity due to gel polymerization. Spatial resolution for dose readout is limited to 0.25--0.5mm pixel size because of available the magnetic field strengths (1.5T and 3T) and the stability of polymer gelatin at room temperature. A reliable glucose-based MAGIC (methacrylic and ascorbic acid in gelatine initiated by copper) gel dosimeter was formulated and evaluated for small field 3D dosimetry using 3T and 7T high field MRI for dose readout. The melting point of the original recipe MAGIC gel was increased by 4°C by adding 10% glucose to improve gel stability. Excellent spatial resolution of 79um (1.5 hr scan) and 39um (12 hr scan) was achieved using 7T MRI, proving gel stability for long scan times and high resolution 3D dosimetry.

Ding, Xuanfeng

102

Accurate patient dosimetry of kilovoltage cone-beam CT in radiation therapy  

SciTech Connect

The increased utilization of x-ray imaging in image-guided radiotherapy has dramatically improved the radiation treatment and the lives of cancer patients. Daily imaging procedures, such as cone-beam computed tomography (CBCT), for patient setup may significantly increase the dose to the patient's normal tissues. This study investigates the dosimetry from a kilovoltage (kV) CBCT for real patient geometries. Monte Carlo simulations were used to study the kV beams from a Varian on-board imager integrated into the Trilogy accelerator. The Monte Carlo calculated results were benchmarked against measurements and good agreement was obtained. The authors developed a novel method to calibrate Monte Carlo simulated beams with measurements using an ionization chamber in which the air-kerma calibration factors are obtained from an Accredited Dosimetry Calibration Laboratory. The authors have introduced a new Monte Carlo calibration factor, f{sub MCcal}, which is determined from the calibration procedure. The accuracy of the new method was validated by experiment. When a Monte Carlo simulated beam has been calibrated, the simulated beam can be used to accurately predict absolute dose distributions in the irradiated media. Using this method the authors calculated dose distributions to patient anatomies from a typical CBCT acquisition for different treatment sites, such as head and neck, lung, and pelvis. Their results have shown that, from a typical head and neck CBCT, doses to soft tissues, such as eye, spinal cord, and brain can be up to 8, 6, and 5 cGy, respectively. The dose to the bone, due to the photoelectric effect, can be as much as 25 cGy, about three times the dose to the soft tissue. The study provides detailed information on the additional doses to the normal tissues of a patient from a typical kV CBCT acquisition. The methodology of the Monte Carlo beam calibration developed and introduced in this study allows the user to calculate both relative and absolute absorbed doses.

Ding, George X.; Duggan, Dennis M.; Coffey, Charles W. [Vanderbilt-Ingram Cancer Center, Department of Radiation Oncology, Vanderbilt University School of Medicine and Department of Physics and Astronomy, Vanderbilt University College of Art and Sciences, B-902, TVC, 1301 Medical Center Drive, Nashville, Tennessee 37232-5671 (United States)

2008-03-15

103

Accurate patient dosimetry of kilovoltage cone-beam CT in radiation therapy.  

PubMed

The increased utilization of x-ray imaging in image-guided radiotherapy has dramatically improved the radiation treatment and the lives of cancer patients. Daily imaging procedures, such as cone-beam computed tomography (CBCT), for patient setup may significantly increase the dose to the patient's normal tissues. This study investigates the dosimetry from a kilovoltage (kV) CBCT for real patient geometries. Monte Carlo simulations were used to study the kV beams from a Varian on-board imager integrated into the Trilogy accelerator. The Monte Carlo calculated results were benchmarked against measurements and good agreement was obtained. The authors developed a novel method to calibrate Monte Carlo simulated beams with measurements using an ionization chamber in which the air-kerma calibration factors are obtained from an Accredited Dosimetry Calibration Laboratory. The authors have introduced a new Monte Carlo calibration factor, fMCcal, which is determined from the calibration procedure. The accuracy of the new method was validated by experiment. When a Monte Carlo simulated beam has been calibrated, the simulated beam can be used to accurately predict absolute dose distributions in the irradiated media. Using this method the authors calculated dose distributions to patient anatomies from a typical CBCT acquisition for different treatment sites, such as head and neck, lung, and pelvis. Their results have shown that, from a typical head and neck CBCT, doses to soft tissues, such as eye, spinal cord, and brain can be up to 8, 6, and 5 cGy, respectively. The dose to the bone, due to the photoelectric effect, can be as much as 25 cGy, about three times the dose to the soft tissue. The study provides detailed information on the additional doses to the normal tissues of a patient from a typical kV CBCT acquisition. The methodology of the Monte Carlo beam calibration developed and introduced in this study allows the user to calculate both relative and absolute absorbed doses. PMID:18404948

Ding, George X; Duggan, Dennis M; Coffey, Charles W

2008-03-01

104

Application of radiation physics to improve dosimetry in early breast cancer radiotherapy  

SciTech Connect

Radiotherapy for early breast cancer has been shown to be a highly effective treatment in a number of long term studies. The radiation dose uniformity of the current standard treatments is often poor, however, with dose variations across the breast much higher than those recommended in international guidelines. This work aimed to explore methods for improving this aspect of the radiation dosimetry of early breast cancer radiotherapy. An experimental method was validated by applying it to computed tomography data from 14 patients with a variety of breast shapes and sizes. The volume of the breast receiving the desired dose levels increased by a mean of 6.9% (range -0.8% to 15.9%) and this benefit was shown to increase with breast volume. The quality of reference images in the verification of treatments was improved by introducing differential filtering to the imaging beams on a radiotherapy simulator. The positive results from the first two studies were applied in a clinical trial (which used the experimental technique). The unique set of data from the trial was analyzed and confirmation of dosimetric improvement, and the increased benefit, for larger breasted women were found. In addition, an analysis of the position of high doses showed these occurred in the upper or lower third of the breast and affected 46% and 30% of patients, respectively, with standard treatment but only 1% of patients with the improved method. Other published methods for improving breast dosimetry were explored by building a simple physical model and carrying out a comparative planning study. The physical model was shown to be effective in predicting the dosimetric consequences of each method. The planning study showed that there was little difference between the methods generally but dosimetric improvement could be increased for larger breast volumes by an appropriate choice of technique. A final study explored how breathing control could be used to reduce cardiac doses in patients with left breast disease. This work has shown that early breast cancer radiotherapy treatments may be significantly improved by applying principles of radiation physics.

Donovan, Ellen Mary [Joint Department of Physics, Royal Marsden Foundation Trust and Institute of Cancer Research, Downs Road, Sutton SM2 5PT (United Kingdom)

2005-07-15

105

Monte Carlo modeling in CT-based geometries: dosimetry for biological modeling experiments with particle beam radiation.  

PubMed

The space radiation environment imposes increased dangers of exposure to ionizing radiation, particularly during a solar particle event (SPE). These events consist primarily of low energy protons that produce a highly inhomogeneous dose distribution. Due to this inherent dose heterogeneity, experiments designed to investigate the radiobiological effects of SPE radiation present difficulties in evaluating and interpreting dose to sensitive organs. To address this challenge, we used the Geant4 Monte Carlo simulation framework to develop dosimetry software that uses computed tomography (CT) images and provides radiation transport simulations incorporating all relevant physical interaction processes. We found that this simulation accurately predicts measured data in phantoms and can be applied to model dose in radiobiological experiments with animal models exposed to charged particle (electron and proton) beams. This study clearly demonstrates the value of Monte Carlo radiation transport methods for two critically interrelated uses: (i) determining the overall dose distribution and dose levels to specific organ systems for animal experiments with SPE-like radiation, and (ii) interpreting the effect of random and systematic variations in experimental variables (e.g. animal movement during long exposures) on the dose distributions and consequent biological effects from SPE-like radiation exposure. The software developed and validated in this study represents a critically important new tool that allows integration of computational and biological modeling for evaluating the biological outcomes of exposures to inhomogeneous SPE-like radiation dose distributions, and has potential applications for other environmental and therapeutic exposure simulations. PMID:24309720

Diffenderfer, Eric S; Dolney, Derek; Schaettler, Maximilian; Sanzari, Jenine K; McDonough, James; Cengel, Keith A

2014-03-01

106

Monte Carlo modeling in CT-based geometries: dosimetry for biological modeling experiments with particle beam radiation  

PubMed Central

The space radiation environment imposes increased dangers of exposure to ionizing radiation, particularly during a solar particle event (SPE). These events consist primarily of low energy protons that produce a highly inhomogeneous dose distribution. Due to this inherent dose heterogeneity, experiments designed to investigate the radiobiological effects of SPE radiation present difficulties in evaluating and interpreting dose to sensitive organs. To address this challenge, we used the Geant4 Monte Carlo simulation framework to develop dosimetry software that uses computed tomography (CT) images and provides radiation transport simulations incorporating all relevant physical interaction processes. We found that this simulation accurately predicts measured data in phantoms and can be applied to model dose in radiobiological experiments with animal models exposed to charged particle (electron and proton) beams. This study clearly demonstrates the value of Monte Carlo radiation transport methods for two critically interrelated uses: (i) determining the overall dose distribution and dose levels to specific organ systems for animal experiments with SPE-like radiation, and (ii) interpreting the effect of random and systematic variations in experimental variables (e.g. animal movement during long exposures) on the dose distributions and consequent biological effects from SPE-like radiation exposure. The software developed and validated in this study represents a critically important new tool that allows integration of computational and biological modeling for evaluating the biological outcomes of exposures to inhomogeneous SPE-like radiation dose distributions, and has potential applications for other environmental and therapeutic exposure simulations. PMID:24309720

Diffenderfer, Eric S.; Dolney, Derek; Schaettler, Maximilian; Sanzari, Jenine K.; Mcdonough, James; Cengel, Keith A.

2014-01-01

107

PREFACE: 8th International Conference on 3D Radiation Dosimetry (IC3DDose)  

NASA Astrophysics Data System (ADS)

IC3DDose 2014, the 8th International Conference on 3D Radiation Dosimetry was held in Ystad, Sweden, from 4-7 September 2014. This grew out of the DosGel series, which began as DosGel99, the 1st International Workshop on Radiation Therapy Gel Dosimetry in Lexington, Kentucky. Since 1999 subsequent DoSGel conferences were held in Brisbane, Australia (2001), Ghent, Belgium (2004), Sherbrooke, Canada (2006) and Crete, Greece (2008). In 2010 the conference was held on Hilton Head Island, South Carolina and underwent a name-change to IC3DDose. The 7th and last meeting was held in Sydney, Australia from 4–8 November 2012. It is worth remembering that the conference series started at the very beginning of the intensity modulated radiotherapy era and that the dosimeters being developed then were, to some extent, ahead of the clinical need of radiotherapy. However, since then the technical developments in radiation therapy have been dramatic, with dynamic treatments, including tracking, gating and volumetric modulated arc therapy, widely introduced in the clinic with the need for 3D dosimetry thus endless. This was also reflected by the contributions at the meeting in Ystad. Accordingly the scope of the meeting has also broadened to IC3DDOSE - I See Three-Dimensional Dose. A multitude of dosimetry techniques and radiation detectors are now represented, all with the common denominator: three-dimensional or 3D. Additionally, quality assurance (QA) procedures and other aspects of clinical dosimetry are represented. The implementation of new dosimetric techniques in radiotherapy is a process that needs every kind of caution, carefulness and thorough validation. Therefore, the clinical needs, reformulated as the aims for IC3DDOSE - I See Three-Dimensional Dose, are: • Enhance the quality and accuracy of radiation therapy treatments through improved clinical dosimetry. • Investigate and understand the dosimetric challenges of modern radiation treatment techniques. • Provide a forum to discuss the latest research and developments in 3D and advanced radiation dosimetry. • Energize and diversify dosimetry research and clinical practice by encouraging interaction and synergy between advanced, 3D, and semi-3D dosimetry techniques. We commend these IC3Dose 2014 conference proceedings to you and strongly believe they include significant contributions to scientific progress in this field. We would like to express our sincere gratitude to everybody involved in making the conference possible, the Scientific committee for their work on the general planning, paper review and program formulation, the distinguished invited speakers for their contributions and the local organizing committee members for all their hard work on the practical preparation for the meeting. Lars E. Olsson, Sven Bäck and Sofie Ceberg Lund University and Skåne University Hospital, Sweden International Scientific Committee Sven Bäck, Sweden (chair) Clive Baldock, Australia Sam Beddar, USA Crister Ceberg, Sweden Yves de Deene, Belgium/Australia Simon Doran, UK Geoffrey Ibbott, USA Andrew Jirasek, Canada Kevin Jordan, Canada Martin Lepage, Canada Daniel Low, USA Mark Oldham, USA Tony Popescu, Canada John Schreiner, Canada Cheng-Shie Wuu, USA David Thwaites, Australia Local Organizing Committee Sofie Ceberg (chair) Lars E. Olsson (conference chair) Fredrik Nordstrom Anneli Edvardsson Anna Karlsson Hauer Anna Bäck

Olsson, Lars E.; Bäck, S.; Ceberg, Sofie

2015-01-01

108

Performance characteristics of a high-level solid-state personnel dosimetry system in pulsed radiation environments  

SciTech Connect

The Health Physics Research Reactor at Oak Ridge National Laboratory was used to evaluate performance characteristics of a high-level, solid-state, personnel-dosimetry system developed for the US Army for the rapid measurement of total(gamma plus neutron) radiation doses to soldiers in locations where tactical nuclear weapons could be used. The gamma-sensitive element of the dosemeter consists of a silver-activated phosphate glass and the neutron detector is a silicon diode. Areas considered in this evaluation included pre-irradiation dose indication: accuracy and precision of gamma, neutron, and total dose measurements; time dependence; and temperature effects. Study results indicate that for doses above about 0.4 Gy, the system can provide rapid and accurate dose estimates within accuracy limits specified by several international regulatory and standards agencies for criticality accident dosimetry. However, theoretical and observed lower limits of detection for this system are somewhat higher than the 0.25 Gy minimum dose of interest for general-accident dosimetry.

Swaja, R.E.; Oyan, R.; Sims, C.S.; Dooley, M.A.

1986-01-01

109

Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry  

NASA Astrophysics Data System (ADS)

Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

Singh, Vishwanath P.; Badiger, N. M.

2014-11-01

110

Somatic aberration induction in Tradescantia occidentalis by neutrons, x- and gamma-radiations. I. Dosimetry.  

PubMed

The dosimetry is described for an investigation of the induction of somatic aberrations in Tradescantia occidentalis by substantially mono-energetic neutrons in the energy range 100 keV to 15 MeV, by 200 keV X-rays and cobalt-60 gamma-radiation. Spectrometry was carried out for both neutrons and X-rays. Neutron fluence was measured by uranium fission chambers. Two types of ionization chamber were employed for dose measurement. One chamber was manufactured of CH-plastic and filled with acetylene and the other of graphite and filled with carbon dioxide. Dosimetry for X- and gamma-radiation was by means of lithium fluoride thermoluminescent dosemeters calibrated against a Victoreen ionization chamber. PMID:1084865

Dennis, J A; Delafield, H J; Peaple, L H; Boot, S J

1976-04-01

111

BREN Tower: A Monument to the Material Culture of Radiation Dosimetry Research  

SciTech Connect

With a height of more than 1,500 feet, the BREN (Bare Reactor Experiment, Nevada) Tower dominates the surrounding desert landscape of the Nevada Test Site. Associated with the nuclear research and atmospheric testing programs carried out during the 1950s and 1960s, the tower was a vital component in a series of experiments aimed at characterizing radiation fields from nuclear detonations. Research programs conducted at the tower provided the data for the baseline dosimetry studies crucial to determining the radiation dose rates received by the atomic bomb survivors of Hiroshima and Nagasaki, Japan. Today, BREN Tower stands as a monument to early dosimetry research and one of the legacies of the Cold War.

Susan Edwards

2008-05-30

112

High resolution 3D dosimetry for microbeam radiation therapy using optical CT  

NASA Astrophysics Data System (ADS)

Optical Computed Tomography (CT) is a promising technique for dosimetry of Microbeam Radiation Therapy (MRT), providing high resolution 3D dose maps. Here different MRT irradiation geometries are visualised showing the potential of Optical CT as a tool for future MRT trials. The Peak-to-Valley dose ratio (PVDR) is calculated to be 7 at a depth of 3mm in the radiochromic dosimeter PRESAGE®. This is significantly lower than predicted values and possible reasons for this are discussed.

McErlean, C.; Bräuer-Krisch, E.; Adamovics, J.; Leach, M. O.; Doran, S. J.

2015-01-01

113

A scintillating GEM for 2D-dosimetry in radiation therapy  

Microsoft Academic Search

The first results of a study on the properties of a gaseous scintillation detector based on a Gas Electron Multiplier (GEM) are reported. The detector is designed for use in position-sensitive dosimetry applications in radiation therapy. A double GEM system, operating in a 90-10% Ar-CO2 gas mixture at a gas amplification factor of ~3000, emits a sufficient amount of detectable

J. H. Timmer; T. L. van Vuure; V. Bom; C. W. van Eijk; J. de Haas; J. M. Schippers

2002-01-01

114

A scintillating GEM for 2D-dosimetry in radiation therapy  

Microsoft Academic Search

The first results of a study on the properties of a gaseous scintillation detector based on a Gas Electron Multiplier (GEM) are reported. The detector is designed for use in position-sensitive dosimetry applications in radiation therapy. A double GEM system, operating in a 90–10% Ar–CO2 gas mixture at a gas amplification factor of ?3000, emits a sufficient amount of detectable

J. H. Timmer; T. L. van Vuure; V. Bom; C. W. van Eijk; J. de Haas; J. M. Schippers

2002-01-01

115

ASSESSMENT OF UNCERTAINTY IN THE RADIATION DOSES FOR THE TECHA RIVER DOSIMETRY SYSTEM  

SciTech Connect

In order to provide more accurate and precise estimates of individual dose (and thus more precise estimates of radiation risk) for the members of the ETRC, a new dosimetric calculation system, the Techa River Dosimetry System-2009 (TRDS-2009) has been prepared. The deterministic version of the improved dosimetry system TRDS-2009D was basically completed in April 2009. Recent developments in evaluation of dose-response models in light of uncertain dose have highlighted the importance of different types of uncertainties in the development of individual dose estimates. These include uncertain parameters that may be either shared or unshared within the dosimetric cohort, and also the nature of the type of uncertainty as aleatory or epistemic and either classical or Berkson. This report identifies the nature of the various input parameters and calculational methods incorporated in the Techa River Dosimetry System (based on the TRDS-2009D implementation), with the intention of preparing a stochastic version to estimate the uncertainties in the dose estimates. This report reviews the equations, databases, and input parameters, and then identifies the author’s interpretations of their general nature. It presents the approach selected so that the stochastic, Monte-Carlo, implementation of the dosimetry System - TRDS-2009MC - will provide useful information regarding the uncertainties of the doses.

Napier, Bruce A.; Degteva, M. O.; Anspaugh, L. R.; Shagina, N. B.

2009-10-23

116

GENII: The Hanford Environmental Radiation Dosimetry Software System: Volume 1, Conceptual representation  

SciTech Connect

The Hanford Environmental Dosimetry Upgrade Project was undertaken to incorporate the internal dosimetry models recommended by the International Commission on Radiological Protection (ICRP) in updated versions of the environmental pathway analysis models used at Hanford. The resulting second generation of Hanford environmental dosimetry computer codes is compiled in the Hanford Environmental Dosimetry System (Generation II, or GENII). The purpose of this coupled system of computer codes is to analyze environmental contamination resulting from acute or chronic releases to, or initial contamination of, air, water, or soil. This is accomplished by calculating radiation doses to individuals or populations. GENII is described in three volumes of documentation. The first volume describes the theoretical considerations of the system. The second volume is a Users' Manual, providing code structure, users' instructions, required system configurations, and QA-related topics. The third volume is a Code Maintenance Manual for the user who requires knowledge of code detail. It includes code logic diagrams, global dictionary, worksheets, example hand calculations, and listings of the code and its associated data libraries. 72 refs., 15 figs., 34 tabs.

Napier, B.A.; Peloquin, R.A.; Strenge, D.L.; Ramsdell, J.V.

1988-12-01

117

Computational dosimetry  

SciTech Connect

The paper presents a definition of the term ``Computational Dosimetry`` that is interpreted as the sub-discipline of computational physics which is devoted to radiation metrology. It is shown that computational dosimetry is more than a mere collection of computational methods. Computational simulations directed at basic understanding and modelling are important tools provided by computational dosimetry, while another very important application is the support that it can give to the design, optimization and analysis of experiments. However, the primary task of computational dosimetry is to reduce the variance in the determination of absorbed dose (and its related quantities), for example in the disciplines of radiological protection and radiation therapy. In this paper emphasis is given to the discussion of potential pitfalls in the applications of computational dosimetry and recommendations are given for their avoidance. The need for comparison of calculated and experimental data whenever possible is strongly stressed.

Siebert, B.R.L.; Thomas, R.H.

1996-01-01

118

Three-dimensional dosimetry of small megavoltage radiation fields using radiochromic gels and optical CT scanning  

NASA Astrophysics Data System (ADS)

The dosimetry of small fields as used in stereotactic radiotherapy, radiosurgery and intensity-modulated radiation therapy can be challenging and inaccurate due to partial volume averaging effects and possible disruption of charged particle equilibrium. Consequently, there exists a need for an integrating, tissue equivalent dosimeter with high spatial resolution to avoid perturbing the radiation beam and artificially broadening the measured beam penumbra. In this work, radiochromic ferrous xylenol-orange (FX) and leuco crystal violet (LCV) micelle gels were used to measure relative dose factors (RDFs), percent depth dose profiles and relative lateral beam profiles of 6 MV x-ray pencil beams of diameter 28.1, 9.8 and 4.9 mm. The pencil beams were produced via stereotactic collimators mounted on a Varian 2100 EX linear accelerator. The gels were read using optical computed tomography (CT). Data sets were compared quantitatively with dosimetric measurements made with radiographic (Kodak EDR2) and radiochromic (GAFChromic® EBT) film, respectively. Using a fast cone-beam optical CT scanner (Vista™), corrections for diffusion in the FX gel data yielded RDFs that were comparable to those obtained by minimally diffusing LCV gels. Considering EBT film-measured RDF data as reference, cone-beam CT-scanned LCV gel data, corrected for scattered stray light, were found to be in agreement within 0.5% and -0.6% for the 9.8 and 4.9 mm diameter fields, respectively. The validity of the scattered stray light correction was confirmed by general agreement with RDF data obtained from the same LCV gel read out with a laser CT scanner that is less prone to the acceptance of scattered stray light. Percent depth dose profiles and lateral beam profiles were found to agree within experimental error for the FX gel (corrected for diffusion), LCV gel (corrected for scattered stray light), and EBT and EDR2 films. The results from this study reveal that a three-dimensional dosimetry method utilizing optical CT-scanned radiochromic gels allows for the acquisition of a self-consistent volumetric data set in a single exposure, with sufficient spatial resolution to accurately characterize small fields.

Babic, Steven; McNiven, Andrea; Battista, Jerry; Jordan, Kevin

2009-04-01

119

Three-dimensional dosimetry of small megavoltage radiation fields using radiochromic gels and optical CT scanning.  

PubMed

The dosimetry of small fields as used in stereotactic radiotherapy, radiosurgery and intensity-modulated radiation therapy can be challenging and inaccurate due to partial volume averaging effects and possible disruption of charged particle equilibrium. Consequently, there exists a need for an integrating, tissue equivalent dosimeter with high spatial resolution to avoid perturbing the radiation beam and artificially broadening the measured beam penumbra. In this work, radiochromic ferrous xylenol-orange (FX) and leuco crystal violet (LCV) micelle gels were used to measure relative dose factors (RDFs), percent depth dose profiles and relative lateral beam profiles of 6 MV x-ray pencil beams of diameter 28.1, 9.8 and 4.9 mm. The pencil beams were produced via stereotactic collimators mounted on a Varian 2100 EX linear accelerator. The gels were read using optical computed tomography (CT). Data sets were compared quantitatively with dosimetric measurements made with radiographic (Kodak EDR2) and radiochromic (GAFChromic EBT) film, respectively. Using a fast cone-beam optical CT scanner (Vista), corrections for diffusion in the FX gel data yielded RDFs that were comparable to those obtained by minimally diffusing LCV gels. Considering EBT film-measured RDF data as reference, cone-beam CT-scanned LCV gel data, corrected for scattered stray light, were found to be in agreement within 0.5% and -0.6% for the 9.8 and 4.9 mm diameter fields, respectively. The validity of the scattered stray light correction was confirmed by general agreement with RDF data obtained from the same LCV gel read out with a laser CT scanner that is less prone to the acceptance of scattered stray light. Percent depth dose profiles and lateral beam profiles were found to agree within experimental error for the FX gel (corrected for diffusion), LCV gel (corrected for scattered stray light), and EBT and EDR2 films. The results from this study reveal that a three-dimensional dosimetry method utilizing optical CT-scanned radiochromic gels allows for the acquisition of a self-consistent volumetric data set in a single exposure, with sufficient spatial resolution to accurately characterize small fields. PMID:19336848

Babic, Steven; McNiven, Andrea; Battista, Jerry; Jordan, Kevin

2009-04-21

120

1987 Annual Conference on Nuclear and Space Radiation Effects, Snowmass Village, CO, July 28-31, 1987, Proceedings  

NASA Technical Reports Server (NTRS)

Various papers on nuclear and space radiation effects are presented. The general topics addressed include: basic mechanisms of radiation effects, single-event phenomena, temperature and field effects, modeling and characterization of radiation effects, IC radiation effects and hardening, and EMP/SGEMP/IEMP phenomena. Also considered are: dosimetry/energy-dependent effects, sensors in and for radiation environments, spacecraft charging and space radiation effects, radiation effects and devices, radiation effects on isolation technologies, and hardness assurance and testing techniques.

1987-01-01

121

An investigation of PRESAGE® 3D dosimetry for IMRT and VMAT radiation therapy treatment verification  

NASA Astrophysics Data System (ADS)

The purpose of this work was to characterize three formulations of PRESAGE® dosimeters (DEA-1, DEA-2, and DX) and to identify optimal readout timing and procedures for accurate in-house 3D dosimetry. The optimal formulation and procedure was then applied for the verification of an intensity modulated radiation therapy (IMRT) and a volumetric modulated arc therapy (VMAT) treatment technique. PRESAGE® formulations were studied for their temporal stability post-irradiation, sensitivity, and linearity of dose response. Dosimeters were read out using a high-resolution optical-CT scanner. Small volumes of PRESAGE® were irradiated to investigate possible differences in sensitivity for large and small volumes (‘volume effect’). The optimal formulation and read-out technique was applied to the verification of two patient treatments: an IMRT plan and a VMAT plan. A gradual decrease in post-irradiation optical-density was observed in all formulations with DEA-1 exhibiting the best temporal stability with less than 4% variation between 2–22?h post-irradiation. A linear dose response at the 4?h time point was observed for all formulations with an R2 value >0.99. A large volume effect was observed for DEA-1 with sensitivity of the large dosimeter being ~63% less than the sensitivity of the cuvettes. For the IMRT and VMAT treatments, the 3D gamma passing rates for 3%/3?mm criteria using absolute measured dose were 99.6 and 94.5% for the IMRT and VMAT treatments, respectively. In summary, this work shows that accurate 3D dosimetry is possible with all three PRESAGE® formulations. The optimal imaging windows post-irradiation were 3–24?h, 2–6?h, and immediately for the DEA-1, DEA-2, and DX formulations, respectively. Because of the large volume effect, small volume cuvettes are not yet a reliable method for calibration of larger dosimeters to absolute dose. Finally, PRESAGE® is observed to be a useful method of 3D verification when careful consideration is given to the temporal stability and imaging protocols for the specific formulation used.

Jackson, Jake; Juang, Titania; Adamovics, John; Oldham, Mark

2015-03-01

122

An investigation of PRESAGE(®) 3D dosimetry for IMRT and VMAT radiation therapy treatment verification.  

PubMed

The purpose of this work was to characterize three formulations of PRESAGE(®) dosimeters (DEA-1, DEA-2, and DX) and to identify optimal readout timing and procedures for accurate in-house 3D dosimetry. The optimal formulation and procedure was then applied for the verification of an intensity modulated radiation therapy (IMRT) and a volumetric modulated arc therapy (VMAT) treatment technique.PRESAGE(®) formulations were studied for their temporal stability post-irradiation, sensitivity, and linearity of dose response. Dosimeters were read out using a high-resolution optical-CT scanner. Small volumes of PRESAGE(®) were irradiated to investigate possible differences in sensitivity for large and small volumes ('volume effect'). The optimal formulation and read-out technique was applied to the verification of two patient treatments: an IMRT plan and a VMAT plan.A gradual decrease in post-irradiation optical-density was observed in all formulations with DEA-1 exhibiting the best temporal stability with less than 4% variation between 2-22?h post-irradiation. A linear dose response at the 4?h time point was observed for all formulations with an R(2) value >0.99. A large volume effect was observed for DEA-1 with sensitivity of the large dosimeter being ~63% less than the sensitivity of the cuvettes. For the IMRT and VMAT treatments, the 3D gamma passing rates for 3%/3?mm criteria using absolute measured dose were 99.6 and 94.5% for the IMRT and VMAT treatments, respectively.In summary, this work shows that accurate 3D dosimetry is possible with all three PRESAGE(®) formulations. The optimal imaging windows post-irradiation were 3-24?h, 2-6?h, and immediately for the DEA-1, DEA-2, and DX formulations, respectively. Because of the large volume effect, small volume cuvettes are not yet a reliable method for calibration of larger dosimeters to absolute dose. Finally, PRESAGE(®) is observed to be a useful method of 3D verification when careful consideration is given to the temporal stability and imaging protocols for the specific formulation used. PMID:25683902

Jackson, Jake; Juang, Titania; Adamovics, John; Oldham, Mark

2015-03-21

123

A method for estimating occupational radiation dose to individuals, using weekly dosimetry data  

SciTech Connect

Statistical analyses of data from epidemiologic studies of workers exposed to radiation have been based on recorded annual radiation doses. It is usually assumed that the annual dose values are known exactly, although it is generally recognized that the data contain uncertainty due to measurement error and bias. We propose the use of a probability distribution to describe an individual`s dose during a specific period of time. Statistical methods for estimating this dose distribution are developed. The methods take into account the ``measurement error`` that is produced by the dosimetry system, and the bias that was introduced by policies that lead to right censoring of small doses as zero. The method is applied to a sample of dose histories obtained from hard copy dosimetry records at Oak Ridge National Laboratory (ORNL). The result of this evaluation raises serious questions about the validity of the historical personnel dosimetry data that is currently being used in low-dose studies of nuclear industry workers. In particular, it appears that there was a systematic underestimation of doses for ORNL workers. This could result in biased estimates of dose-response coefficients and their standard errors.

Mitchell, T.J.; Ostrouchov, G.; Frome, E.L.; Kerr, G.D.

1993-12-01

124

SCINTILLATION METHOD FOR DOSIMETRY OF ROENTGEN AND GAMMA RADIATION  

Microsoft Academic Search

The high radiation sensitivity of an air-equivalent scintillator is ; discussed. The possibility of creating a scintillation dosimeter with a high ; radiation sensitivity not worse than plus or minus 6.0% in the energy range 30-; 130 kev with efficiency not less than 0.1 mr\\/hr is considered. The possibility ; of increasing the efficiency is also discussed. (tr-auth);

M. I. Arsaev; N. E. Sulimova

1963-01-01

125

Automation of radiation dosimetry using PTW dosemeter and LabVIEW™  

NASA Astrophysics Data System (ADS)

Automation of UNIDOS "Dosemeter" using personal computer (PC) is discussed in this paper. In order to save time and eliminate human operation errors during the radiation dosimetry, suitable software, using LabVIEW™ graphical programming language, was written to automate and facilitate the processes of measurements, analysis and data storage. The software calculates the calibration factor of the ionization chamber in terms of air kerma or absorbed dose to water according to IAEA dosimetry protocols. It also has the ability to print a calibration certificate. The obtained results using this software are found to be more reliable and flexible than those obtained by manual methods previously employed. Using LabVIEW™ as a development tool is extremely convenient to make things easier when software modifications and improvements are needed.

Weiss, C.; Al-Frouh, K.; Anjak, O.

2011-10-01

126

DESCRIPTION OF MODULAR DEVICES FOR THE MEASUREMENT OF EXTERNAL DOSIMETRY IN RADIATION PROTECTION.  

PubMed

In 2002 the Group of Radiation Dosimetry and Calibration of the Belgian Nuclear Research Centre (SCK•CEN) has developed an experimental device based on the optically stimulated luminescence (OSL) working with Al2O3:C detectors (TLD-500 and Luxel) stimulated with an argon laser. A set of devices made from different modules have been developed to permit external dosimetry measurements with thermoluminescence (TL) and OSL techniques under different conditions. This study describes these measurement devices that can be made with these modules and some of the characteristics of the different systems. These devices present several advantages in terms of measurement possibilities: a small number of modules allow the use of different detection materials (Al2O3:C, BeO, quartz electronic components and tiles) and different measurement methods (TL, CW-OSL and pulsed OSL). Some applications are commented. PMID:25236335

Genicot, Jean Louis; Boogers, Eric; Van Iersel, Mark

2014-09-18

127

Dosimetry protocol for the preclinical trials in white-beam minibeam radiation therapy  

SciTech Connect

Purpose: In the quest of a curative radiotherapy treatment for gliomas, new delivery modes are being explored. At the Biomedical Beamline of the European Synchrotron Radiation Facility, a new spatially fractionated technique, called minibeam radiation therapy (MBRT), is under development. The aims of this work were to assess different dosimetric aspects and to establish a dosimetry protocol to be applied in the forthcoming animal (rat) studies in order to evaluate the therapeutic index of this new radiotherapy approach. Methods: Absolute dosimetry was performed with a thimble ionization chamber (PTW semiflex 31010) whose center was positioned at 2 g cm{sup -2} depth. To translate the dose measured in broad beam configuration to the dose deposited with a minibeam, the scatter factors were used. Those were assessed by using the Monte Carlo simulations and verified experimentally with Gafchromic films and a Bragg Peak chamber. The comparison of the theoretical and experimental data were used to benchmark the calculations. Finally, the dose distributions in a rat phantom were evaluated by using the validated Monte Carlo calculations. Results: The absolute dosimetry in broad beam configuration was measured in reference conditions. The dose rate was in the range between 168 and 224 Gy/min, depending on the storage ring current. A scatter factor of 0.80 {+-} 0.04 was obtained. Percentage depth dose and lateral profiles were evaluated both in homogenous and heterogeneous slab phantoms. The general good agreement between Monte Carlo simulations and experimental data permitted the benchmark of the calculations. Finally, the peak doses in the rat head phantom were assessed from the measurements in reference conditions. In addition, the peak-to-valley dose ratio values as a function of depth in the rat head were evaluated. Conclusions: A new promising radiotherapy approach is being explored at the ESRF: Minibeam Radiation Therapy. To assess the therapeutic index of this new modality, in vivo experiments are being planned, for which an accurate knowledge of the dosimetry is essential. For that purpose, a complete set of measurements and Monte Carlo simulations was performed. The first dosimetry protocol for preclinical trials in minibeam radiation therapy was established. This protocol allows to have reproducibility in terms of dose for the different biological studies.

Prezado, Y.; Martinez-Rovira, I.; Thengumpallil, S.; Deman, P. [ID17 Biomedical Beamline, European Synchrotron Radiation Facility (ESRF), 6, Rue Jules Horowitz B.P.220, 38043 Grenoble (France); ID17 Biomedical Beamline, European Synchrotron Radiation Facility (ESRF), 6, Rue Jules Horowitz B.P. 220, 38043 Grenoble Cedex (France) and Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, E-08028 Barcelona (Spain); ID17 Biomedical Beamline, European Synchrotron Radiation Facility (ESRF), 6, Rue Jules Horowitz B.P.220, 38043 Grenoble (France) and Dipartimento di Fisica ''E. Amaldi'', Universita degli Studi Roma Tre, 84, Via della Vasca Navale, 00146 Rome (Italy); ID17 Biomedical Beamline, European Synchrotron Radiation Facility (ESRF), 6, Rue Jules Horowitz B.P.220, 38043 Grenoble (France); INSERM, U836, Equipe 6, F-38042 Grenoble 9 (France) and University Grenoble 1, F-38041 Grenoble (France)

2011-09-15

128

Ion-kill dosimetry  

NASA Technical Reports Server (NTRS)

Unanticipated late effects in neutron and heavy ion therapy, not attributable to overdose, imply a qualitative difference between low and high LET therapy. We identify that difference as 'ion kill', associated with the spectrum of z/beta in the radiation field, whose measurement we label 'ion-kill dosimetry'.

Katz, R.; Cucinotta, F. A.; Fromm, M.; Chambaudet, A.

2001-01-01

129

A hybrid radiation detector for simultaneous spatial and temporal dosimetry.  

PubMed

In this feasibility study an organic plastic scintillator is calibrated against ionisation chamber measurements and then embedded in a polymer gel dosimeter to obtain a quasi-4D radiation detector. This hybrid dosimeter was irradiated with megavoltage x-rays from a linear accelerator, with temporal measurements of the dose rate being acquired by the scintillator and spatial measurements acquired with the gel dosimeter. The detectors employed in this study are radiologically equivalent; and we show that neither detector perturbs the intensity of the radiation field of the other. By employing these detectors in concert, spatial and temporal variations in the radiation intensity can now be detected and gel dosimeters can be calibrated for absolute dose from a single irradiation. PMID:21678102

Poole, C; Trapp, J V; Kenny, J; Kairn, T; Williams, K; Taylor, M; Franich, R; Langton, C M

2011-09-01

130

Space radiation dosimetry on US and Soviet manned missions  

NASA Technical Reports Server (NTRS)

Radiation measurements obtained on board U.S. and Soviet spacecraft are presented and discussed. A considerable amount of data has now been collected and analyzed from measurements with a variety of detector types in low-Earth orbit. The objectives of these measurements have been to investigate the dose and Linear Energy Transfer (LET) spectra within the complex shielding of large spacecraft. The shielding modifies the external radiation (trapped protons, electrons, cosmic ray nuclei) which, in turn, is quite dependent on orbital parameters (altitude, inclination). For manned flights, these measurements provide a crew exposure record and a data base for future spacecraft design and flight planning. For the scientific community they provide useful information for planning and analyzing data from experiments with high sensitivity to radiation. In this paper, results of measurements by both passive and active detectors are described. High-LET spectra measurements were obtained by means of plastic nuclear track detectors (PNTD's) while thermoluminescent dosimeters (TLD's) measured the dose.

Parnell, T. A.; Benton, E. V.

1995-01-01

131

A Novel Technique for Performing Space Based Radiation Dosimetry Using DNA-Results from GRaDEx-I and the Design of GRaDEx-II  

NASA Technical Reports Server (NTRS)

Because of the large amounts of cosmic radiation in the space environment relative to that on earth, the effects of radiation on the physiology of astronauts is of major concern. Doses of radiation which can cause acute or chronic biological effects are to be avoided, therefore determination of the amount of radiation exposure encountered during space flight and assessment of its impact on biological systems is critical. Quantifying the radiation dosage and damage to biological systems, especially to humans during repetitive high altitude flight and during long duration space flight is important for several reasons. Radiation can cause altered biosynthesis and long term genotoxicity resulting in cancer and birth defects etc. Radiation damage to biological systems depends in a complex way on incident radiation species and their energy spectra. Typically non-biological, i.e. film or electronic monitoring systems with narrow energy band sensitivity are used to perform dosimetry and then results are extrapolated to biological models. For this reason it may be desirable to perform radiation dosimetry by using biological molecules e.g. DNA or RNA strands as passive sensors. A lightweight genotoxicology experiment was constructed to determine the degree to which in vitro naked DNA extracted from tissues of a variety of vertebrate organisms is damaged by exposure to radiation in a space environment. The DNA is assayed by means of agarose gel electrophoresis to determine damage such as strand breakage caused by high momentum particles and photons, and base oxidation caused by free radicals. The length distribution of DNA fragments is directly correlated with the radiation dose. It is hoped that a low mass, low cost, passive biological system to determine dose response relationship (increase in strand breaks with increase in exposure) can be developed to perform radiation dosimetry in support of long duration space flight, and to predict negative effects on biological systems (e.g. astronauts and greenhouses) in space. The payload was flown in a 2.5 cubic foot Get Away Special (GAS) container through NASA's GAS program. It was subjected to the environment of the space shuttle cargo bay for the duration of the STS-91 mission (9 days). Results of the genotoxicology and radiation dosimetry experiment (GRaDEx-1) as well as the design of an improved follow on payload are presented.

Ritter, Joe; Branly, R.; Theodorakis, C.; Bickham, J.; Swartz, C.; Friedfeld, R.; Ackerman, E.; Carruthers, C.; DiGirolamo, A.; Faranda, J.

1999-01-01

132

A Novel Technique for Performing Space Based Radiation Dosimetry Using DNA: Results from GRaDEx-I and the Design of GRaDEx-II  

NASA Technical Reports Server (NTRS)

Because of the large amounts of cosmic radiation in the space environment relative to that on earth, the effects of radiation on the physiology of astronauts is of major concern. Doses of radiation which can cause acute or chronic biological effects are to be avoided, therefore determination of the amount of radiation exposure encountered during space flight and assessment of its impact on biological systems is critical. Quantifying the radiation dosage and damage to biological systems, especially to humans during repetitive high altitude flight and during long duration space flight is important for several reasons. Radiation can cause altered biosynthesis and long term genotoxicity resulting in cancer and birth defects, etc. Radiation damage to biological systems depends in a complex way on incident radiation species and their energy spectra. Typically non-biological, i.e. film or electronic monitoring systems with narrow energy band sensitivity are used to perform dosimetry and then results are extrapolated to biological models. For this reason it may be desirable to perform radiation dosimetry by using biological molecules e.g. DNA or RNA strands as passive sensors. A lightweight genotoxicology experiment was constructed to determine the degree to which in-vitro naked DNA extracted from tissues of a variety of vertebrate organisms is damaged by exposure to radiation in a space environment. The DNA is assayed by means of agarose gel electrophoresis to determine damage such as strand breakage caused by high momentum particles and photons, and base oxidation caused by free radicals. The length distribution of DNA fragments is directly correlated with the radiation dose. It is hoped that a low mass, low cost, passive biological system to determine dose-response relationship (increase in strand breaks with increase in exposure) can be developed to perform radiation dosimetry in support of long duration space flight, and to predict negative effects on biological systems (e.g. astronauts and greenhouses) in space. The payload was flown in a 2.5 cubic foot Get Away Special (GAS) container through NASA's GAS program. It was subjected to the environment of the space shuttle cargo bay for the duration of the STS-91 mission (9 days). Results of the genotoxicology and radiation dosimetry experiment (GRaDEx-I) as well as the design of an improved follow on payload are presented.

Ritter, Joe; Branly, R.; Theodorakis, C.; Bickham, J.; Swartz, C.; Friedfeld, R.; Ackerman, E.; Carruthers, C.; DiGirolamo, A.; Faranda, J.; Howard, E.; Bruno, C.

1999-01-01

133

Radiation dosimetry for intrasynovial administration of Sm153 particulates  

Microsoft Academic Search

Radiation therapy to the synovial joint using Sm-153 is a promising area of inquiry. A particulate agent under development at Mallinckrodt Medical, Inc. was evaluated in eleven rabbits (six normals and five with antigen-induced-arthritis (AIA)). Radioactivity was assayed in eight tissues plus blood and urine, after injection of activity into the stifle, with samples gathered as late as 6 days.

M. G. Stabin; J. W. Brodack; K. F. Deutsch

1994-01-01

134

ORIGINAL ARTICLE Biodistribution and radiation dosimetry of a positron  

E-print Network

of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan P. The purposes of this study were to estimate the radiation-absorbed doses of 18 F-SP203 in humans plasma [2]. Merck developed another ligand, 18 F-MTEB, and reported studies in monkeys [5] but have

Shen, Jun

135

Bibliographical database of radiation biological dosimetry and risk assessment: Part 1, through June 1988  

SciTech Connect

This database was constructed to support research in radiation biological dosimetry and risk assessment. Relevant publications were identified through detailed searches of national and international electronic databases and through our personal knowledge of the subject. Publications were numbered and key worded, and referenced in an electronic data-retrieval system that permits quick access through computerized searches on publication number, authors, key words, title, year, and journal name. Photocopies of all publications contained in the database are maintained in a file that is numerically arranged by citation number. This report of the database is provided as a useful reference and overview. It should be emphasized that the database will grow as new citations are added to it. With that in mind, we arranged this report in order of ascending citation number so that follow-up reports will simply extend this document. The database cite 1212 publications. Publications are from 119 different scientific journals, 27 of these journals are cited at least 5 times. It also contains reference to 42 books and published symposia, and 129 reports. Information relevant to radiation biological dosimetry and risk assessment is widely distributed among the scientific literature, although a few journals clearly dominate. The four journals publishing the largest number of relevant papers are Health Physics, Mutation Research, Radiation Research, and International Journal of Radiation Biology. Publications in Health Physics make up almost 10% of the current database.

Straume, T.; Ricker, Y.; Thut, M.

1988-08-29

136

Dosimetry by ESR spectroscopy following a radiation accident.  

PubMed

On 2 September, 1982, one of the employees of the gamma-irradiation facility at The Institute for Energy and Technology (Kjeller, Norway) entered the irradiation cell with a 65.7-kCi 60Co source in unshielded position. The victim received an unknown radiation dose and died after 13 days. Using electron-spin resonance spectroscopy (ESR), the radiation dose in this accident was subsequently determined based on the production of long-lived free radicals in nitroglycerol tablets carried by the operator during accident. He used nitroglycerol for heart problems and free radicals are easily formed and trapped in sugar which is the main component of the tablets. Calibration experiments were carried out and the dose given to the tablets during the accident was determined to be 39 Gy. Phantom experiments based on this result indicate an average whole-body dose in the accident of 22.5 Gy. PMID:6315638

Sagstuen, E; Theisen, H; Henriksen, T

1983-11-01

137

The radiation oncology workforce: a focus on medical dosimetry.  

PubMed

The 2012 Radiation Oncology Workforce survey was conducted to assess the current state of the entire workforce, predict its future needs and concerns, and evaluate quality improvement and safety within the field. This article describes the dosimetrist segment results. The American Society for Radiation Oncology (ASTRO) Workforce Subcommittee, in conjunction with other specialty societies, conducted an online survey targeting all segments of the radiation oncology treatment team. The data from the dosimetrist respondents are presented in this article. Of the 2573 dosimetrists who were surveyed, 890 responded, which resulted in a 35% segment response rate. Most respondents were women (67%), whereas only a third were men (33%). More than half of the medical dosimetrists were older than 45 years (69.2%), whereas the 45 to 54 years age group represented the highest percentage of respondents (37%). Most medical dosimetrists stated that their workload was appropriate (52%), with respondents working a reported average of 41.7 ± 4 hours per week. Overall, 86% of medical dosimetrists indicated that they were satisfied with their career, and 69% were satisfied in their current position. Overall, 61% of respondents felt that there was an oversupply of medical dosimetrists in the field, 14% reported that supply and demand was balanced, and the remaining 25% felt that there was an undersupply. The medical dosimetrists? greatest concerns included documentation/paperwork (78%), uninsured patients (80%), and insufficient reimbursement rates (87%). This survey provided an insight into the dosimetrist perspective of the radiation oncology workforce. Though an overwhelming majority has conveyed satisfaction concerning their career, the study allowed a spotlight to be placed on the profession?s current concerns, such as insufficient reimbursement rates and possible oversupply of dosimetrists within the field. PMID:24630911

Robinson, Gregg F; Mobile, Katherine; Yu, Yan

2014-01-01

138

Genetic and molecular dosimetry of HZE radiation (7-IML-1)  

NASA Technical Reports Server (NTRS)

The objectives of the study are to determine the kinetics of production and to characterize the unique aspects of genetic and developmental lesion induced in animal cells by radiation present in the space environment. Special attention is given to heavy charged particles. The organism Caenorhabditis elegans, a simple nematode, is used as a model system for a coordinated set of ground-based and flight experiments.

Nelson, Gregory A.

1992-01-01

139

Gene Expression-Based Dosimetry by Dose and Time in Mice Following Acute Radiation Exposure  

PubMed Central

Rapid and reliable methods for performing biological dosimetry are of paramount importance in the event of a large-scale nuclear event. Traditional dosimetry approaches lack the requisite rapid assessment capability, ease of use, portability and low cost, which are factors needed for triaging a large number of victims. Here we describe the results of experiments in which mice were acutely exposed to 60Co gamma rays at doses of 0 (control) to 10 Gy. Blood was obtained from irradiated mice 0.5, 1, 2, 3, 5, and 7 days after exposure. mRNA expression levels of 106 selected genes were obtained by reverse-transcription real time PCR. Stepwise regression of dose received against individual gene transcript expression levels provided optimal dosimetry at each time point. The results indicate that only 4–7 different gene transcripts are needed to explain ? 0.69 of the variance (R2), and that receiver-operator characteristics, a measure of sensitivity and specificity, of ? 0.93 for these statistical models were achieved at each time point. These models provide an excellent description of the relationship between the actual and predicted doses up to 6 Gy. At doses of 8 and 10 Gy there appears to be saturation of the radiation-response signals with a corresponding diminution of accuracy. These results suggest that similar analyses in humans may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations. PMID:24358280

Tucker, James D.; Divine, George W.; Grever, William E.; Thomas, Robert A.; Joiner, Michael C.; Smolinski, Joseph M.; Auner, Gregory W.

2013-01-01

140

Gene expression-based dosimetry by dose and time in mice following acute radiation exposure.  

PubMed

Rapid and reliable methods for performing biological dosimetry are of paramount importance in the event of a large-scale nuclear event. Traditional dosimetry approaches lack the requisite rapid assessment capability, ease of use, portability and low cost, which are factors needed for triaging a large number of victims. Here we describe the results of experiments in which mice were acutely exposed to (60)Co gamma rays at doses of 0 (control) to 10 Gy. Blood was obtained from irradiated mice 0.5, 1, 2, 3, 5, and 7 days after exposure. mRNA expression levels of 106 selected genes were obtained by reverse-transcription real time PCR. Stepwise regression of dose received against individual gene transcript expression levels provided optimal dosimetry at each time point. The results indicate that only 4-7 different gene transcripts are needed to explain ? 0.69 of the variance (R(2)), and that receiver-operator characteristics, a measure of sensitivity and specificity, of ? 0.93 for these statistical models were achieved at each time point. These models provide an excellent description of the relationship between the actual and predicted doses up to 6 Gy. At doses of 8 and 10 Gy there appears to be saturation of the radiation-response signals with a corresponding diminution of accuracy. These results suggest that similar analyses in humans may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations. PMID:24358280

Tucker, James D; Divine, George W; Grever, William E; Thomas, Robert A; Joiner, Michael C; Smolinski, Joseph M; Auner, Gregory W

2013-01-01

141

Radiochromic film dosimetry of HDR {sup 192}Ir source radiation fields  

SciTech Connect

Purpose: A radiochromic film based dosimetry system for high dose rate (HDR) Iridium-192 brachytherapy source was described. A comparison between calibration curves established in water and Solid Water was provided. Methods: Pieces of EBT-2 model GAFCHROMIC film were irradiated in both water and Solid Water with HDR {sup 192}Ir brachytherapy source in a dose range from 0 to 50 Gy. Responses of EBT-2 GAFCHROMIC film were compared for irradiations in water and Solid Water by scaling the dose between media through Monte Carlo calculated conversion factor for both setups. To decrease uncertainty in dose delivery due to positioning of the film piece with respect to the radiation source, traceable calibration irradiations were performed in a parallel-opposed beam setup. Results: The EBT-2 GAFCHROMIC film based dosimetry system described in this work can provide an overall one-sigma dose uncertainty of 4.12% for doses above 1 Gy. The ratio of dose delivered to the sensitive layer of the film in water to the dose delivered to the sensitive layer of the film in Solid Water was calculated using Monte Carlo simulations to be 0.9941 {+-} 0.0007. Conclusions: A radiochromic film based dosimetry system using only the green color channel of a flatbed document scanner showed superior precision if used alone in a dose range that extends up to 50 Gy, which greatly decreases the complexity of work. In addition, Solid Water material was shown to be a viable alternative to water in performing radiochromic film based dosimetry with HDR {sup 192}Ir brachytherapy sources.

Aldelaijan, Saad; Mohammed, Huriyyah; Tomic, Nada; Liang Liheng; DeBlois, Francois; Sarfehnia, Arman; Abdel-Rahman, Wamied; Seuntjens, Jan; Devic, Slobodan [Medical Physics Unit, McGill University, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2 (Canada); Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4 (Canada); Medical Physics Unit, McGill University, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2 (Canada)

2011-11-15

142

Review on the characteristics of radiation detectors for dosimetry and imaging  

NASA Astrophysics Data System (ADS)

The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general discussion of the application of detectors for x-ray nuclear medicine and ion beam imaging and dosimetry is presented.

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-01

143

Dosimetry protocol for the forthcoming clinical trials in synchrotron stereotactic radiation therapy (SSRT)  

SciTech Connect

Purpose: An adequate dosimetry protocol for synchrotron radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron stereotactic radiation therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. Methods: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm{sup -2} equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irradiation. Different correction factors have been assessed by using Monte Carlo simulations. Results: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18 Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. Conclusions: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.

Prezado, Y.; Vautrin, M.; Martinez-Rovira, I. [ID17 Biomedical Beamline, European Synchrotron Radiation Facility (ESRF), 38043 Grenoble (France); and others

2011-03-15

144

Review on the characteristics of radiation detectors for dosimetry and imaging.  

PubMed

The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general discussion of the application of detectors for x-ray nuclear medicine and ion beam imaging and dosimetry is presented. PMID:25229250

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-10-21

145

Hanford Technical Basis for Multiple Dosimetry Effective Dose Methodology  

SciTech Connect

The current method at Hanford for dealing with the results from multiple dosimeters worn during non-uniform irradiation is to use a compartmentalization method to calculate the effective dose (E). The method, as documented in the current version of Section 6.9.3 in the 'Hanford External Dosimetry Technical Basis Manual, PNL-MA-842,' is based on the compartmentalization method presented in the 1997 ANSI/HPS N13.41 standard, 'Criteria for Performing Multiple Dosimetry.' With the adoption of the ICRP 60 methodology in the 2007 revision to 10 CFR 835 came changes that have a direct affect on the compartmentalization method described in the 1997 ANSI/HPS N13.41 standard, and, thus, to the method used at Hanford. The ANSI/HPS N13.41 standard committee is in the process of updating the standard, but the changes to the standard have not yet been approved. And, the drafts of the revision of the standard tend to align more with ICRP 60 than with the changes specified in the 2007 revision to 10 CFR 835. Therefore, a revised method for calculating effective dose from non-uniform external irradiation using a compartmental method was developed using the tissue weighting factors and remainder organs specified in 10 CFR 835 (2007).

Hill, Robin L.; Rathbone, Bruce A.

2010-08-01

146

Radiation dosimetry at the BNL Medical Research Reactor  

SciTech Connect

The Medical Research Reactor, BMRR, at the Brookhaven National Laboratory, BNL, is a three megawatt, 3 MW, heterogeneous, tank-type, light water cooled and moderated, graphite reflected reactor, which was designed for biomedical studies, and became operational in 1959. It provides thermal and epithermal neutron beams suitable for research studies such as radiation therapy of various types of tumors. At the present time, the major program at BMRR is Boron Neutron Capture Therapy, BNCT. Modifications have been made to the BMRR to significantly increase the available epithermal neutron flux density to a patient in clinical trials of BNCT. The data indicate that the flux density and dose rate are concentrated in the center of the beam, the patient absorbs neutrons rather than gamma radiation and as noted previously even with the increasing flux values, gamma-ray dose received by the attending personnel has remained minimal. Flux densities in the center of the thermal port and epithermal port beams have been characterized with an agreement between the measurements and the calculations.

Holden, N.E.; Reciniello, R.N.; Greenberg, D.D.; Hu, J.P.

1998-11-01

147

Multi-dimensional fiber-optic radiation sensor for ocular proton therapy dosimetry  

NASA Astrophysics Data System (ADS)

In this study, we fabricated a multi-dimensional fiber-optic radiation sensor, which consists of organic scintillators, plastic optical fibers and a water phantom with a polymethyl methacrylate structure for the ocular proton therapy dosimetry. For the purpose of sensor characterization, we measured the spread out Bragg-peak of 120 MeV proton beam using a one-dimensional sensor array, which has 30 fiber-optic radiation sensors with a 1.5 mm interval. A uniform region of spread out Bragg-peak using the one-dimensional fiber-optic radiation sensor was obtained from 20 to 25 mm depth of a phantom. In addition, the Bragg-peak of 109 MeV proton beam was measured at the depth of 11.5 mm of a phantom using a two-dimensional sensor array, which has 10×3 sensor array with a 0.5 mm interval.

Jang, K. W.; Yoo, W. J.; Moon, J.; Han, K. T.; Park, B. G.; Shin, D.; Park, S.-Y.; Lee, B.

2012-12-01

148

Automated radiofrequency radiation dosimetry. Final report, Jun 89-Sep 90  

SciTech Connect

The interaction of radiofrequency (RF) and microwave (MW) electromagnetic radiation with biological tissues is of increasing importance from the standpoint of health and safety. From considerable literature devoted to the study of RF and MW bioeffects based primarily on animal experimentation it has been determined that bioeffects are correlated with mass-normalized rates of RF or MW energy absorption (specific absorption rates or SARs). An emphasis of our project was to improve the efficiency of the SAR algorithms and to extend their use to higher RF and MW frequencies. Another objective was to adapt these algorithms to computing workstations and distributed memory parallel processors that are becoming more affordable and hence readily available to potential users of these codes.

Gandhi, O.P.

1990-12-01

149

Ce{sup 3+}-doped fibers for remote radiation dosimetry  

SciTech Connect

A radioluminescent (RL) dosimetric system, based on a SiO{sub 2} optical fiber with the core doped by Ce{sup 3+} ions as luminescent activators has been investigated. Structural and optical properties of the luminescent fiber have been studied by Raman, refractive index, RL and scintillation time decay measurements, and compared to those obtained on bulk material. The RL response of a composite fiber made of a short portion of active Ce-doped fiber coupled to a long commercial one has been investigated by x-ray irradiation. A linear RL intensity response has been found in the dose rate interval 6x10{sup -3}-40 mGy/s together with a good radiation hardness, suggesting possible application in low-dose monitoring.

Vedda, A.; Chiodini, N.; Di Martino, D.; Fasoli, M.; Keffer, S.; Lauria, A.; Martini, M.; Moretti, F.; Spinolo, G.; Nikl, M.; Solovieva, N.; Brambilla, G. [Department of Materials Science and INFM/CNR, University of Milano-Bicocca, Via Cozzi 53, I-20125 Milan (Italy); Institute of Physics ASCR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Optoelectronics Research Centre, University of Southampton, Southampton, S0171BJ (United Kingdom)

2004-12-27

150

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

NASA Astrophysics Data System (ADS)

This work quantifies the changes effected in electron absorbed dose to a soft-tissue equivalent medium when part of this medium is replaced by a material that is not soft -tissue equivalent. That is, heterogeneous dosimetry is addressed. Radionuclides which emit beta particles are the electron sources of primary interest. They are used in brachytherapy and in nuclear medicine: for example, beta -ray applicators made with strontium-90 are employed in certain ophthalmic treatments and iodine-131 is used to test thyroid function. More recent medical procedures under development and which involve beta radionuclides include radioimmunotherapy and radiation synovectomy; the first is a cancer modality and the second deals with the treatment of rheumatoid arthritis. In addition, the possibility of skin surface contamination exists whenever there is handling of radioactive material. Determination of absorbed doses in the examples of the preceding paragraph requires considering boundaries of interfaces. Whilst the Monte Carlo method can be applied to boundary calculations, for routine work such as in clinical situations, or in other circumstances where doses need to be determined quickly, analytical dosimetry would be invaluable. Unfortunately, few analytical methods for boundary beta dosimetry exist. Furthermore, the accuracy of results from both Monte Carlo and analytical methods has to be assessed. Although restricted to one radionuclide, phosphorus -32, the experimental data obtained in this work serve several purposes, one of which is to provide standards against which calculated results can be tested. The experimental data also contribute to the relatively sparse set of published boundary dosimetry data. At the same time, they may be useful in developing analytical boundary dosimetry methodology. The first application of the experimental data is demonstrated. Results from two Monte Carlo codes and two analytical methods, which were developed elsewhere, are compared with experimental data. Monte Carlo results compare satisfactory with experimental results for the boundaries considered. The agreement with experimental results for air interfaces is of particular interest because of discrepancies reported previously by another investigator who used data obtained from a different experimental technique. Results from one of the analytical methods differ significantly from the experimental data obtained here. The second analytical method provided data which approximate experimental results to within 30%. This is encouraging but it remains to be determined whether this method performs equally well for other source energies.

Nunes, Josane C.

1991-02-01

151

Plastic scintillation dosimetry for radiation therapy: minimizing capture of Cerenkov radiation noise  

Microsoft Academic Search

Over the last decade, there has been an increased interest in scintillation dosimetry using small water-equivalent plastic scintillators, because of their favourable characteristics when compared with other more commonly used detector systems. Although plastic scintillators have been shown to have many desirable dosimetric properties, as yet there is no successful commercial detector system of this type available for routine clinical

A Sam Beddar; Natalka Suchowerska; Susan H Law

2004-01-01

152

Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications.  

PubMed

During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al(2)O(3):C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al(2)O(3):C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF(3):Eu(2+) appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al(2)O(3):C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose measurements in clinical applications. A brief review of the recent developments is presented. PMID:19893698

Pradhan, A S; Lee, J I; Kim, J L

2008-07-01

153

Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications  

PubMed Central

During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al2O3:C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al2O3:C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF3:Eu2+ appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al2O3:C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose measurements in clinical applications. A brief review of the recent developments is presented. PMID:19893698

Pradhan, A. S.; Lee, J. I.; Kim, J. L.

2008-01-01

154

Ion storage dosimetry  

NASA Astrophysics Data System (ADS)

The availability of a reliable, accurate and cost-effective real-time personnel dosimetry system is fascinating to radiation workers. Electronic dosimeters are contemplated to meet this demand of active dosimetry. The development of direct ion storage (DIS) dosimeters, a member of the electronic dosimeter family, for personnel dosimetry is also an attempt in this direction. DIS dosimeter is a hybrid of the well-established technology of ion chambers and the latest advances in data storage using metal oxide semiconductor field effect transistor (MOSFET) analog memory device. This dosimeter is capable of monitoring legal occupational radiation doses of gamma, X-rays, beta and neutron radiation. Similar to an ion chamber, the performance of the dosimeter for a particular application can be optimized through the selection of appropriate wall materials. The use of the floating gate of a MOSFET as one of the electrodes of the ion chamber allows the miniaturization of the device to the size of a dosimetry badge and avoids the use of power supplies during dose accumulation. The concept of the device, underlying physics and the design of the DIS dosimeter are discussed. The results of preliminary testing of the device are also provided.

Mathur, V. K.

2001-09-01

155

Biodistribution and radiation dosimetry of radioiodinated hypericin as a cancer therapeutic.  

PubMed

Iodine-131?labeled monoiodohypericin (131I?Hyp) is a necrosis avid compound used as a complementary anticancer agent. Herein, the biodistribution in rats with re-perfused partial liver infarction (RPLI) was used to estimate its human internal radiation dosimetry. Iodine-123?labeled monoiodohypericin (123I-Hyp) as a safer surrogate for 131I-Hyp was prepared with iodogen as oxidant. Determination of radiochemical yield and purification was performed by high performance liquid chromatography (HPLC). To control aggregation, the formulation was macroscopically and microscopically examined. Biodistribution of 123I-Hyp was studied in RPLI rats (n=18) at 4, 24 and 48 h post-injection. Tissue gamma counting (TGC), autoradiography and histology were performed. Dosimetry of 131I-Hyp in hepatic necrosis and in normal human organs was estimated using biodistribution data of 123I-Hyp, the Organ Level Internal Dose Assessment/Exponential Modeling (OLINDA/EXM®), a sphere model and male and female phantoms. A radiochemical yield of 95% was achieved in labeling of 123I-Hyp with a radiochemical purity of 99% after HPLC purification. In the Hyp added formulation, no macroscopic but minimal microscopic aggregation was observed. By TGC, selective accumulation in hepatic infarction and low uptake in viable liver of 123I?Hyp/Hyp were detected, as confirmed by autoradiography and histology. Significantly higher doses of 131I-Hyp were delivered to necrotic (276?93,600 mGy/MBq) than to viable (4.2 mGy/MBq) liver (P<0.05). In normal organs, 123I?Hyp was eliminated within 24 h except for relatively high levels in the lungs and thyroid. Hepatobiliary elimination was a major pathway of 123I-Hyp causing high activity in the intestines. For both genders, dosimetry showed the longest residence time of 131I-Hyp in the remainder, followed by the lungs, intestines and thyroid. The highest absorbed radiation dose was seen in necrotic tissues and the shortest residence times and lowest absorbed radiation dose were found in the brain. 131I-Hyp selectively delivers higher radiation dose to necrosis compared with the rest of the body. Among normal organs, thyroids, lungs and intestines receive considerable radiation dose, which deserves cautious attention in developing this anticancer approach. PMID:24366374

Cona, Marlein Miranda; Koole, Michel; Feng, Yuanbo; Liu, Yewei; Verbruggen, Alfons; Oyen, Raymond; Ni, Yicheng

2014-03-01

156

1989 IEEE Annual Conference on Nuclear and Space Radiation Effects, 26th, Marco Island, FL, July 25-29, 1989, Proceedings. Part 1  

NASA Technical Reports Server (NTRS)

Various papers on nuclear science are presented. The general topics addressed include: basic mechanics of radiation effects, dosimetry and energy-dependent effects, hardness assurance and testing techniques, spacecraft charging and space radiation effects, EMP/SGEMP/IEMP phenomena, device radiation effects and hardening, radiation effects on isolation technologies, IC radiation effects and hardening, and single-event phenomena.

Ochoa, Agustin, Jr. (editor)

1989-01-01

157

Radiation dosimetry data management using VAX C, FMS, RMS, DCL, and Oracle  

SciTech Connect

The External Dosimetry Badge System was developed to support the radiation protection program at Los Alamos National Laboratory. The radiation protection program is responsible for monitoring external radiation exposures to approximately 7,500 Laboratory employees, visitors and contractors each month. External radiation exposure is measured using thermoluminescent dosimeters (TLDs). The system is used to control the assembly and distribution of TLD badges. The system monitors badge return and disassembly at the end of each month, and analyzes the TLDs to determine individual radiation exposure levels. Results are reported and stored in a database designed to maintain detailed individual exposure records. The system maintains a complete history of annual summaries for external exposures. The system is user-friendly with user prompts, menus, and extensive help functions. The completely menu-driven system uses VAX C, VAX Forms Management System, VMS Record Management Services, VMS Digital Command Language, and the Oracle Relational Database Management System. Design and development issues faced, and methods and techniques used in developing the system will be described. Topics discussed include consistent user interface design approaches, considerations for using VAX/VMS programming tools versus Oracle development tools to develop and implement the application, and overall system benefits. 3 refs.

Voltin, M.J. Jr.; Martin, A.K.

1991-01-01

158

Annual Conference on Nuclear and Space Radiation Effects, 16th, Santa Cruz, Calif., July 17-20, 1979, Proceedings  

NASA Technical Reports Server (NTRS)

Papers are presented on the following topics: radiation effects in bipolar microcircuits; basic radiation mechanisms in materials and devices; energy deposition and dosimetry; and system responses from SGEMP, IEMP, and EMP. Also considered are basic processes in SGEMP and IEMP, radiation effects in MOS microcircuits, and space radiation effects and spacecraft charging.

Bombardt, J.

1979-01-01

159

Toward 3D dosimetry of intensity modulated radiation therapy treatments with plastic scintillation detectors  

NASA Astrophysics Data System (ADS)

In this work, we present a novel two Dimensional Plastic Scintillation Detector (2D-PSD) array designed to measure dose distributions generated by high energy photon beams from medical linear accelerators. This study aim to demonstrate that the dose distribution in the irradiated volume is not modified by the presence of several hundred plastic scintillation detectors (PSDs). The 2D-PSD consists of 781 PSDs inserted in a plastic water slab. The dose distributions measured with the 2D-PSD were compared to calculations from a treatment planning system (Pinnacle3, Philips Medical Systems) and with measurements taken with an ionization chambers array (MatriXX Evolution, IBA Dosimetry). Furthermore, a clinical head and neck IMRT plan was delivered on the 2D-PSD. A good agreement is obtained between the measured and planned dose distributions. The results show that the 2D arrangement presented in this work is water equivalent and transparent to x-ray radiation. As a consequence, our design could be extended to multiple detection planes, opening the possibility for 3D dosimetry with PSDs.

Guillot, M.; Gingras, L.; Archambault, L.; Beddar, S.; Beaulieu, L.

2010-11-01

160

Review of radiation dosimetry research at the University of Wisconsin during 1961-1982  

SciTech Connect

The report provides a comprehensive review of the overall activities in this program since 1961. Research areas have included the development and use of lithium fluoride for thermoluminescent dosimetry, solid state neutron dosimetry, and ionization chamber research. (ACR)

Cameron, J.R.; Moran, P.R.; Attix, F.H.

1982-01-01

161

Low-energy x-ray dosimetry studies (7 to 17.5 keV) with synchroton radiation  

SciTech Connect

Unique properties of synchrotron radiation (SR), such as its high intensity, brightness, polarization, and broad spectral distribution (extending from x-ray to infra-red wavelengths) make it an attractive light source for numerous experiments. As SR facilities are rapidly being built all over the world, they introduce the need for low-energy x-ray dosemeters because of the potential radiation exposure to experimenters. However, they also provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory are described. Lithium fluoride TLDs (TLD-100) of varying thicknesses (0.015 to 0.08 cm) were exposed free in air to monochromatic x-rays (7 to 17.5 keV). These exposures were monitored with ionization chambers. The response (nC/Gy) was found to increase with increasing TLD thickness and with increasing beam energy. A steeper increase in response with increasing energy was observed with the thicker TLDs. The responses at 7 and 17.5 keV were within a factor of 2.3 and 5.2 for the 0.015 and 0.08 cm-thick TLDs, respectively. The effects of narrow (beam size smaller than the dosemeter) and broad (beam size larger than the dosemeter) beams on the response of the TLDs are also reported.

Ipe, N.E.; Bellamy, H.; Flood, J.R. [and others

1995-06-01

162

Epid Dosimetry  

SciTech Connect

Electronic portal imaging devices (EPIDs) were introduced originally for patient position verification. The idea of using EPIDs for dosimetry was realised in the 1980s. Little was published on the topic until the mid 1990's, when the interest in EPIDs for dosimetry increased rapidly and continues to grow. The increasing research on EPID dosimetry coincided with the introduction of intensity modulated radiation therapy (IMRT). EPIDs are well suited to IMRT dosimetry because they are high resolution, two-dimensional (2D) digital detectors. They are also pre-existing on almost all modern linear accelerators. They generally show a linear response to increasing dose. Different types of EPIDs have been clinically implemented, and these have been described in several review papers. The current generation of commercially available EPIDs are indirect detection active matrix flat panel imagers, also known as amorphous silicon (a-Si) EPIDs. Disadvantages of a-Si EPIDs for dosimetry include non-water equivalent construction materials, and the energy sensitivity and optical scatter of the phosphor scintillators used to create optical signal from the megavoltage beam. This report discusses current knowledge regarding a-Si EPIDs for dosimetry.

Greer, Peter B. [Dept.Radiation Oncology, Calvary Mater Newcastle Hospital, Locked Bag 7, Hunter Region Mail Centre, Newcastle, NSW 2310 (Australia); Mathematical and Physical Sciences, University of Newcastle, Callaghan, NSW 2298 (Australia); Vial, Philip [Dept Medical Physics, Liverpool and Macarthur Cancer Therapy Centre, Liverpool, NSW 2170 (Australia); School of Physics, University of Sydney, Camperdown, NSW 2050 (Australia)

2011-05-05

163

Epid Dosimetry  

NASA Astrophysics Data System (ADS)

Electronic portal imaging devices (EPIDs) were introduced originally for patient position verification. The idea of using EPIDs for dosimetry was realised in the 1980s. Little was published on the topic until the mid 1990's, when the interest in EPIDs for dosimetry increased rapidly and continues to grow. The increasing research on EPID dosimetry coincided with the introduction of intensity modulated radiation therapy (IMRT). EPIDs are well suited to IMRT dosimetry because they are high resolution, two-dimensional (2D) digital detectors. They are also pre-existing on almost all modern linear accelerators. They generally show a linear response to increasing dose. Different types of EPIDs have been clinically implemented, and these have been described in several review papers. The current generation of commercially available EPIDs are indirect detection active matrix flat panel imagers, also known as amorphous silicon (a-Si) EPIDs. Disadvantages of a-Si EPIDs for dosimetry include non-water equivalent construction materials, and the energy sensitivity and optical scatter of the phosphor scintillators used to create optical signal from the megavoltage beam. This report discusses current knowledge regarding a-Si EPIDs for dosimetry.

Greer, Peter B.; Vial, Philip

2011-05-01

164

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak  

SciTech Connect

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points – three TLDs per point – to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

Rasouli, C.; Pourshahab, B.; Rasouli, H. [Plasma Physics and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, AEOI, PO Box 14155-1339, Tehran (Iran, Islamic Republic of)] [Plasma Physics and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, AEOI, PO Box 14155-1339, Tehran (Iran, Islamic Republic of); Hosseini Pooya, S. M.; Orouji, T. [Radiation Application Research School, Nuclear Science and Technology Research Institute, AEOI, PO Box 14155-1339, Tehran (Iran, Islamic Republic of)] [Radiation Application Research School, Nuclear Science and Technology Research Institute, AEOI, PO Box 14155-1339, Tehran (Iran, Islamic Republic of)

2014-05-15

165

Performance of neutron and gamma personnel dosimetry in mixed radiation fields  

SciTech Connect

From 1974 to 1980, six personnel dosimetry intercomparison studies (PDIS) were conducted at the Oak Ridge National Laboratory (ORNL) to evaluate the performance of personnel dosimeters in a variety of neutron and gamma fields produced by operating the Health Physics Research Reactor (HPRR) in the steady state mode with and without spectral modifying shields. A total of 58 different organizations participated in these studies which produced approximately 2000 measurements of neutron and gamma dose equivalents on anthropomorphic phantoms for five different reactor spectra. Based on these data, the relative performance of three basic types of neutron dosimeters (nuclear emulsion film, thermoluminescent (TLD), and track-etch) and two basic types of gamma dosimeters (film and TLD) in mixed radiation fields was assessed.

Swaja, R.E.; Sims, C.S.

1981-01-01

166

Development and Validation of a GEANT4 Radiation Transport Code for CT Dosimetry.  

PubMed

The authors have created a radiation transport code using the GEANT4 Monte Carlo toolkit to simulate pediatric patients undergoing CT examinations. The focus of this paper is to validate their simulation with real-world physical dosimetry measurements using two independent techniques. Exposure measurements were made with a standard 100-mm CT pencil ionization chamber, and absorbed doses were also measured using optically stimulated luminescent (OSL) dosimeters. Measurements were made in air with a standard 16-cm acrylic head phantom and with a standard 32-cm acrylic body phantom. Physical dose measurements determined from the ionization chamber in air for 100 and 120 kVp beam energies were used to derive photon-fluence calibration factors. Both ion chamber and OSL measurement results provide useful comparisons in the validation of the Monte Carlo simulations. It was found that simulated and measured CTDI values were within an overall average of 6% of each other. PMID:25706135

Carver, D E; Kost, S D; Fernald, M J; Lewis, K G; Fraser, N D; Pickens, D R; Price, R R; Stabin, M G

2015-04-01

167

Fabrication and optimization of a fiber-optic radiation sensor for proton beam dosimetry  

NASA Astrophysics Data System (ADS)

In this study, we fabricated a fiber-optic radiation sensor for proton therapy dosimetry and measured the output and the peak-to-plateau ratio of scintillation light with various kinds of organic scintillators in order to select an organic scintillator appropriate for measuring the dose of a proton beam. For the optimization of an organic scintillator, the linearity between the light output and the stopping power of a proton beam was evaluated for two different diameters of the scintillator, and the angular dependency and standard deviation of the light pulses were investigated for four different scintillator lengths. We also evaluated the linearity between the light output and the dose rate and monitor units of a proton generator, respectively. The relative depth-dose curve of the proton beam was obtained and corrected using Birk's theory.

Jang, K. W.; Yoo, W. J.; Seo, J. K.; Heo, J. Y.; Moon, J.; Park, J.-Y.; Hwang, E. J.; Shin, D.; Park, S.-Y.; Cho, H.-S.; Lee, B.

2011-10-01

168

Thermoluminescence properties of LiF:Mg,Cu,Na,Si pellets in radiation dosimetry.  

PubMed

Sintered LiF:Mg,Cu,Na,Si thermoluminescence (TL) pellets have been developed for application in radiation dosimetry. LiF:M,Cu,Na,Si TL pellets were made from TL powders using a sintering process, that is, pressing and heat treatment. These pellets have a diameter of 4.5 mm, and a thickness of 0.8 mm are blue in colour and have a mass of 28 mg each. After 400 pellets had been produced they were irradiated with 137Cs gamma radiation and samples having a sensitivity within a +/-5% standard deviation were selected for experimental use. In the present study, the physical and dosimetric properties of LiF:Mg,Cu,Na,Si TL pellets were investigated for their emission spectrum, dose response, energy response and fading characteristics. Photon irradiation for the experiments was carried out using X ray beams and a 137Cs gamma source at the Korea Atomic Energy Research Institute (KAERI). The average energies and the dose were in the range of 20-662 keV and 10(-6) - 10(2) Gy respectively. The glow curves were measured with a manual type thermoluminescence dosimetry reader (system 310, Teledyne) at a constant nitrogen flux and a linear heating rate. For a constant heating rate of 5 degrees C.s(-1). the main dosimetric peak of the glow curve appeared at 234 degrees C, its activation energy was 2.34 eV and the frequency factor was 1.00 x 10(23). The TL emission spectrum appeared at the blue region centred at 410 nm. A linearity of photon dose response was maintained up to 100 Gy. The photon energy responses relative to the 137Cs response were within +/-20% in the overall photon energy region. No fading of the TL sensitivity of the pellets stored at room temperature was found over the course of a year. Therefore LiF:Mg,Cu,Na,Si TL pellets can be used for personal dosimetry, but more research is needed to improve the characteristics for repeated use. PMID:12382923

Nam, Y M; Kim, J L

2002-01-01

169

Potential application of pure silica optical flat fibers for radiation therapy dosimetry  

NASA Astrophysics Data System (ADS)

Pure silica optical flat fibers (FF) have been proposed as the basis for a novel radiation sensor by the measurement of the thermoluminescence (TL) produced. In this paper the TL performance of the FFs were studied. Using a linear accelerator (LINAC) delivering doses in the range 0.2-10.0 Gy, the TL dosimetric glow curves of the FFs were studied with respect to 6 MeV electron and 6 MV photon beams. When exposed to 6 MeV electron irradiation, the pure silica FFs displayed a supralinear response starting from 2 Gy up to 10.0 Gy. While for 6 MV photon irradiation, the FFs shows linear characteristic (f(D)=1) nearly up to 2 Gy. The TL intensity (Im) of the main peak of FFs is 1.5 times higher for 6 MeV electron beams than for 6 MV photon beams. The maximum peak temperature (Tm) it is not affected by the type of irradiation used at the same dose while the maximum TL intensity (Im) was found to be dependent on the type of radiation used. Overall results indicate that the pure silica FFs can be used as radiation sensors in the high-dose therapy dosimetry.

Alawiah, A.; Bauk, S.; Abdul-Rashid, H. A.; Gieszczyk, W.; Hashim, S.; Mahdiraji, G. A.; Tamchek, N.; Bradley, D. A.

2015-01-01

170

Advances in a framework to compare bio-dosimetry methods for triage in large-scale radiation events.  

PubMed

Planning and preparation for a large-scale nuclear event would be advanced by assessing the applicability of potentially available bio-dosimetry methods. Using an updated comparative framework the performance of six bio-dosimetry methods was compared for five different population sizes (100-1,000,000) and two rates for initiating processing of the marker (15 or 15,000 people per hour) with four additional time windows. These updated factors are extrinsic to the bio-dosimetry methods themselves but have direct effects on each method's ability to begin processing individuals and the size of the population that can be accommodated. The results indicate that increased population size, along with severely compromised infrastructure, increases the time needed to triage, which decreases the usefulness of many time intensive dosimetry methods. This framework and model for evaluating bio-dosimetry provides important information for policy-makers and response planners to facilitate evaluation of each method and should advance coordination of these methods into effective triage plans. PMID:24729594

Flood, Ann Barry; Boyle, Holly K; Du, Gaixin; Demidenko, Eugene; Nicolalde, Roberto J; Williams, Benjamin B; Swartz, Harold M

2014-06-01

171

Characterization of a parallel-beam CCD optical-CT apparatus for 3D radiation dosimetry.  

PubMed

3D measurement of optical attenuation is of interest in a variety of fields of biomedical importance, including spectrophotometry, optical projection tomography (OPT) and analysis of 3D radiation dosimeters. Accurate, precise and economical 3D measurements of optical density (OD) are a crucial step in enabling 3D radiation dosimeters to enter wider use in clinics. Polymer gels and Fricke gels, as well as dosimeters not based around gels, have been characterized for 3D dosimetry over the last two decades. A separate problem is the verification of the best readout method. A number of different imaging modalities (magnetic resonance imaging (MRI), optical CT, x-ray CT and ultrasound) have been suggested for the readout of information from 3D dosimeters. To date only MRI and laser-based optical CT have been characterized in detail. This paper describes some initial steps we have taken in establishing charge coupled device (CCD)-based optical CT as a viable alternative to MRI for readout of 3D radiation dosimeters. The main advantage of CCD-based optical CT over traditional laser-based optical CT is a speed increase of at least an order of magnitude, while the simplicity of its architecture would lend itself to cheaper implementation than both MRI and laser-based optical CT if the camera itself were inexpensive enough. Specifically, we study the following aspects of optical metrology, using high quality test targets: (i) calibration and quality of absorbance measurements and the camera requirements for 3D dosimetry; (ii) the modulation transfer function (MTF) of individual projections; (iii) signal-to-noise ratio (SNR) in the projection and reconstruction domains; (iv) distortion in the projection domain, depth-of-field (DOF) and telecentricity. The principal results for our current apparatus are as follows: (i) SNR of optical absorbance in projections is better than 120:1 for uniform phantoms in absorbance range 0.3 to 1.6 (and better than 200:1 for absorbances 1.0 to 3.5 with the test target and a novel absorbance range extension method), (ii) the spatial resolution is shown to be at worst 0.5 mm (and often better than this) with an associated DOF of 8 cm, (iii) the SNR of uniform phantoms in reconstruction domain is above 80:1 (one standard deviation) over an absorbance dynamic range of 0.3 to 1.6, (iv) the apparatus is telecentric and without distortion. Finally, a sample scan and reconstruction of a scan of a PRESAGE dosimeter are shown, demonstrating the capabilities of the apparatus. PMID:17664571

Krstaji?, Nikola; Doran, Simon J

2007-07-01

172

Characterization of a parallel-beam CCD optical-CT apparatus for 3D radiation dosimetry  

NASA Astrophysics Data System (ADS)

3D measurement of optical attenuation is of interest in a variety of fields of biomedical importance, including spectrophotometry, optical projection tomography (OPT) and analysis of 3D radiation dosimeters. Accurate, precise and economical 3D measurements of optical density (OD) are a crucial step in enabling 3D radiation dosimeters to enter wider use in clinics. Polymer gels and Fricke gels, as well as dosimeters not based around gels, have been characterized for 3D dosimetry over the last two decades. A separate problem is the verification of the best readout method. A number of different imaging modalities (magnetic resonance imaging (MRI), optical CT, x-ray CT and ultrasound) have been suggested for the readout of information from 3D dosimeters. To date only MRI and laser-based optical CT have been characterized in detail. This paper describes some initial steps we have taken in establishing charge coupled device (CCD)-based optical CT as a viable alternative to MRI for readout of 3D radiation dosimeters. The main advantage of CCD-based optical CT over traditional laser-based optical CT is a speed increase of at least an order of magnitude, while the simplicity of its architecture would lend itself to cheaper implementation than both MRI and laser-based optical CT if the camera itself were inexpensive enough. Specifically, we study the following aspects of optical metrology, using high quality test targets: (i) calibration and quality of absorbance measurements and the camera requirements for 3D dosimetry; (ii) the modulation transfer function (MTF) of individual projections; (iii) signal-to-noise ratio (SNR) in the projection and reconstruction domains; (iv) distortion in the projection domain, depth-of-field (DOF) and telecentricity. The principal results for our current apparatus are as follows: (i) SNR of optical absorbance in projections is better than 120:1 for uniform phantoms in absorbance range 0.3 to 1.6 (and better than 200:1 for absorbances 1.0 to 3.5 with the test target and a novel absorbance range extension method), (ii) the spatial resolution is shown to be at worst 0.5 mm (and often better than this) with an associated DOF of 8 cm, (iii) the SNR of uniform phantoms in reconstruction domain is above 80:1 (one standard deviation) over an absorbance dynamic range of 0.3 to 1.6, (iv) the apparatus is telecentric and without distortion. Finally, a sample scan and reconstruction of a scan of a PRESAGE™ dosimeter are shown, demonstrating the capabilities of the apparatus.

Krstajic, Nikola; Doran, Simon J.

2007-07-01

173

Intercomparison of luminescence detectors for space radiation dosimetry within Proton-ICCHIBAN experiments  

NASA Astrophysics Data System (ADS)

Luminescence detectors for space radiation dosimetry are frequently used to estimate personal and environmental doses in the International Space Station and other space vehicles. Detector responses for cosmic rays and their secondaries were investigated for a long time and it is well-known that luminescence detectors have dependencies of response on LET (Linear Energy Transfer). Some of luminescence detectors show over-response to gamma rays (used for routine calibration) and others have similar responses to gamma rays. But, because of lack of sufficient and reliable calibration data in the low LET region (about 1 keV/?m), it is the responses of these detectors at LET is poorly known. Protons make up the dominant portion of the fluence from space radiation, so the LET region corresponding to energetic protons must be characterized very well. For that purpose, calibration and intercomparison experiments were performed using relatively low energy (30 to 80 MeV) proton beams at the National Institute of Radiological Sciences, Chiba, Japan. In this paper, the results of these intercomparison experiments, including high energy protons and light ions, are reported and illustrate the response of luminescence detectors in the low LET region. This research will help improve our understanding of space dosimeters and reliable dose measurement for astronauts and cosmonauts in low earth orbit.

Uchihori, Yukio; Ploc, Ondrej; Yasuda, Nakahiro; Berger, Thomas; Hajek, Michael; Kodaira, Satoshi; Benton, Eric; Ambrozova, Iva; Kitamura, Hisashi

2012-07-01

174

JPL Radiation Effects Facilities  

NASA Technical Reports Server (NTRS)

Radiation Effects Group investigates the effects of space radiation on present and future microelectronic and optoelectronic technologies, evaluate the risk of using them in specific space missions, and recommend component and design techniques for JPL and NASA programs to reduce reliability risk from space radiation.

Thorbourn, Dennis

2013-01-01

175

Medical radiation exposure and accidents. Dosimetry and radiation protection. Do we only benefit the patient?  

PubMed

This article presents and discusses new information on the old Hippocratic moto of "...not to harm but to benefit the patient". Some radiation accidents are due to medical errors. Millions of medical tests exposing radiation are performed every day worldwide increasing and sometimes exceeding the annual permissible dose administered to the general population. Public authorities are now seriously concerned about medical radiation overused. In U.S.A. both the House of Representatives and the Food and Drug Administration have recently delt with this problem. Others and we have suggested before and the International Atomic Energy Agency now proposes: a "Smart Card" for every individual who receives medical radiation. In this card the amount of medical radiation administered will be recorded. It is time to issue rules for protection of the public from medical radiation overdose. PMID:20808982

Grammaticos, Philip; Lyra, Maria

2010-01-01

176

ASTM dosimetry activities: A progress report  

NASA Astrophysics Data System (ADS)

Radiation dosimetry standards are under development in ASTM on the selection of dosimetry systems for use in the operation of gamma ray or electron beam food processing facilities, on the dosimetry in gamma ray facilities used for radiation-hardness testing of electronic devices, and on the use of dosimetry systems for general applications such as the Fricke and ceric-cerous sulfate dosimeters.

Humphreys, J. C.; Farrar, H.; Fairand, B. P.

177

Radiation effects in space  

SciTech Connect

The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented. (ACR)

Fry, R.J.M.

1986-01-01

178

Estimating the effective density of engineered nanomaterials for in vitro dosimetry  

NASA Astrophysics Data System (ADS)

The need for accurate in vitro dosimetry remains a major obstacle to the development of cost-effective toxicological screening methods for engineered nanomaterials. An important key to accurate in vitro dosimetry is the characterization of sedimentation and diffusion rates of nanoparticles suspended in culture media, which largely depend upon the effective density and diameter of formed agglomerates in suspension. Here we present a rapid and inexpensive method for accurately measuring the effective density of nano-agglomerates in suspension. This novel method is based on the volume of the pellet obtained by benchtop centrifugation of nanomaterial suspensions in a packed cell volume tube, and is validated against gold-standard analytical ultracentrifugation data. This simple and cost-effective method allows nanotoxicologists to correctly model nanoparticle transport, and thus attain accurate dosimetry in cell culture systems, which will greatly advance the development of reliable and efficient methods for toxicological testing and investigation of nano-bio interactions in vitro.

Deloid, Glen; Cohen, Joel M.; Darrah, Tom; Derk, Raymond; Rojanasakul, Liying; Pyrgiotakis, Georgios; Wohlleben, Wendel; Demokritou, Philip

2014-03-01

179

(Biological dosimetry)  

SciTech Connect

The traveler attended the 1st International Conference on Biological Dosimetry in Madrid, Spain. This conference was organized to provide information to a general audience of biologists, physicists, radiotherapists, industrial hygiene personnel and individuals from related fields on the current ability of cytogenetic analysis to provide estimates of radiation dose in cases of occupational or environmental exposure. There is a growing interest in Spain in biological dosimetry because of the increased use of radiation sources for medical and occupational uses, and with this the anticipated and actual increase in numbers of overexposure. The traveler delivered the introductory lecture on Biological Dosimetry: Mechanistic Concepts'' that was intended to provide a framework by which the more applied lectures could be interpreted in a mechanistic way. A second component of the trip was to provide advice with regard to several recent cases of overexposure that had been or were being assessed by the Radiopathology and Radiotherapy Department of the Hospital General Gregorio Maranon'' in Madrid. The traveler had provided information on several of these, and had analyzed cells from some exposed or purportedly exposed individuals. The members of the biological dosimetry group were referred to individuals at REACTS at Oak Ridge Associated Universities for advice on follow-up treatment.

Preston, R.J.

1990-12-17

180

Determination of uncertainty components for a system in Radiation Protection Dosimetry  

NASA Astrophysics Data System (ADS)

This work is about the theoretical calculation of uncertainties associated to the dosimetry of photons of a 137Cs source that will be used in a Dosimetry Laboratory. In this case recognition of the influence quantities that provide most uncertainty and the right choice of resolution of auxiliary equipment to obtain the smallest uncertainties according to the laboratory.

Lopez, F.; Cabral, T. S.; Peixoto, J. G.

2015-01-01

181

MIRD Commentary: Proposed Name for a Dosimetry Unit Applicable to Deterministic Biological Effects-The Barendsen (Bd)  

SciTech Connect

The fundamental physical quantity for relating all biologic effects to radiation exposure is the absorbed dose, the energy imparted per unit mass of tissue. Absorbed dose is expressed in units of joules per kilogram (J/kg) and is given the special name gray (Gy). Exposure to ionizing radiation may cause both deterministic and stochastic biologic effects. To account for the relative effect per unit absorbed dose that has been observed for different types of radiation, the International Commission on Radiological Protection (ICRP) has established radiation weighting factors for stochastic effects. The product of absorbed dose in Gy and the radiation weighting factor is defined as the equivalent dose. Equivalent dose values are designated by a special named unit, the sievert (Sv). Unlike the situation for stochastic effects, no well-defined formalism and associated special named quantities have been widely adopted for deterministic effects. The therapeutic application of radionuclides and, specifically, -particle emitters in nuclear medicine has brought to the forefront the need for a well-defined dosimetry formalism applicable to deterministic effects that is accompanied by corresponding special named quantities. This commentary reviews recent proposals related to this issue and concludes with a recommendation to establish a new named quantity.

Sgouros, George; Howell, R. W.; Bolch, Wesley E.; Fisher, Darrell R.

2009-03-02

182

1990 IEEE Annual Conference on Nuclear and Space Radiation Effects, 27th, Reno, NV, July 16-20, 1990, Proceedings  

NASA Technical Reports Server (NTRS)

Various papers on nuclear and space radiation effects are presented. The general topics addressed include: basic mechanisms of radiation effects, dosimetry and energy-dependent effects, hardness assurance and testing techniques, single-event upset and latchup, isolation technologies, device and integrated circuit effects and hardening, spacecraft charging and electromagnetic effects.

Fleetwood, Daniel M. (editor)

1990-01-01

183

Lithium formate for EPR dosimetry: radiation-induced radical trapping at low temperatures.  

PubMed

Radiation-induced primary radicals in lithium formate. A material used in EPR dosimetry have been studied using electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR) and ENDOR-Induced EPR (EIE) techniques. In this study, single crystals were X irradiated at 6-8 K and radical formation at these and higher temperatures were investigated. Periodic density functional theory calculations were used to assist in assigning the radical structures. Mainly two radicals are present at 6 K, the well-known CO2(•-) radical and a protonated electron-gain product. Hyperfine coupling tensors for proton and lithium interactions were obtained for these two radicals and show that the latter radical exists in four conformations with various degrees of bending at the radical center. Pairs of CO2(•-) radicals were also observed and the tensor for the electron-electron dipolar coupling was determined for the strongest coupled pair, which exhibited the largest spectral intensity. Upon warming, both the radical pairs and the reduction product decay, the latter apparently by a transient species. Above 200 K the EPR spectrum was mainly due to the CO2(•-) (mono) radicals, which were previously characterized as the dominant species present at room temperature and which account for the dosimetric EPR signal. PMID:24720752

Krivokapi?, André; Aalbergsjø, Siv G; De Cooman, Hendrik; Hole, Eli Olaug; Nelson, William H; Sagstuen, Einar

2014-05-01

184

Annual Conference on Nuclear and Space Radiation Effects, 17th, Cornell University, Ithaca, N.Y., July 15-18, 1980, Proceedings  

NASA Technical Reports Server (NTRS)

The conference covered the radiation effects on devices, circuits, and systems, physics and basic radiation effects in materials, dosimetry and radiation transport, spacecraft charging, and space radiation effects. Other subjects included single particle upset phenomena, systems-generated electromagnetic pulse phenomena, fabrication of hardened components, testing techniques, and hardness assurance.

Mcgarrity, J. M.

1980-01-01

185

Digital holographic interferometry: A novel optical calorimetry technique for radiation dosimetry  

SciTech Connect

Purpose: To develop and demonstrate the proof-of-principle of a novel optical calorimetry method to determine radiation absorbed dose in a transparent medium. Methods: The calorimetric property of water is measured during irradiation by means of an interferometer, which detects temperature-induced changes in the refractive index that can be mathematically related to absorbed dose. The proposed method uses a technique called digital holographic interferometry (DHI), which comprises an optical laser interferometer setup and consecutive physical reconstruction of the recorded wave fronts by means of the Fresnel transform. This paper describes the conceptual framework and provides the mathematical basis for DHI dosimetry. Dose distributions from a high dose rate Brachytherapy source were measured by a prototype optical setup to demonstrate the feasibility of the approach. Results: The developed DHI dosimeter successfully determined absorbed dose distributions in water in the region adjacent to a high dose rate Brachytherapy source. A temperature change of 0.0381 K across a distance of 6.8 mm near the source was measured, corresponding to a dose of 159.3 Gy. The standard deviation in a typical measurement set was ±3.45 Gy (corresponding to an uncertainty in the temperature value of ±8.3 × 10{sup ?4} K). The relative dose fall off was in agreement with treatment planning system modeled data. Conclusions: First results with a prototype optical setup and a Brachytherapy source demonstrate the proof-of-principle of the approach. The prototype achieves high spatial resolution of approximately 3 × 10{sup ?5} m. The general approach is fundamentally independent of the radiation type and energy. The sensitivity range determined indicates that the method is predominantly suitable for high dose rate applications. Further work is required to determine absolute dose in all three dimensions.

Cavan, Alicia, E-mail: alicia.cavan@cdhb.health.nz [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand and Christchurch Hospital, Private Bag 4710, Christchurch 8140 (New Zealand)] [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand and Christchurch Hospital, Private Bag 4710, Christchurch 8140 (New Zealand); Meyer, Juergen, E-mail: juergen@uw.edu [Department of Radiation Oncology, University of Washington, 1959 Northeast Pacific Street, Box 356043, Seattle, Washington 98195 (United States)] [Department of Radiation Oncology, University of Washington, 1959 Northeast Pacific Street, Box 356043, Seattle, Washington 98195 (United States)

2014-02-15

186

Validation of QuickScan dicentric chromosome analysis for high throughput radiation biological dosimetry.  

PubMed

Currently, the dicentric chromosome assay (DCA) is used to estimate radiation doses to individuals following accidental radiological and nuclear overexposures when traditional dosimetry methods are not available. While being an exceptionally sensitive method for estimating doses by radiation, conventional DCA is time-intensive and requires highly trained expertise for analysis. For this reason, in a mass casualty situation, triage-quality conventional DCA struggles to provide dose estimations in a timely manner for triage purposes. In Canada, a new scoring technique, termed DCA QuickScan, has been devised to increase the throughput of this assay. DCA QuickScan uses traditional DCA sample preparation methods while adapting a rapid scoring approach. In this study, both conventional and QuickScan methods of scoring the DCA assay were compared for accuracy and sensitivity. Dose response curves were completed on four different donors based on the analysis of 1,000 metaphases or 200 events at eight to nine dose points by eight different scorers across two laboratories. Statistical analysis was performed on the data to compare the two methods within and across the laboratories and to test their respective sensitivities for dose estimation. This study demonstrated that QuickScan is statistically similar to conventional DCA analysis and is capable of producing dose estimates as low as 0.1 Gy but up to six times faster. Therefore, DCA QuickScan analysis can be used as a sensitive and accurate method for scoring samples for radiological biodosimetry in mass casualty situations or where faster dose assessment is required. PMID:22217587

Flegal, F N; Devantier, Y; Marro, L; Wilkins, R C

2012-02-01

187

An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals.  

PubMed

The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms. PMID:24353030

Andersson, M; Johansson, L; Minarik, D; Mattsson, S; Leide-Svegborn, S

2014-12-01

188

From ``micro`` to ``macro`` internal dosimetry  

SciTech Connect

Radiation dose is the amount of radiation energy deposited per unit mass of absorbing tissue. Internal dosimetry applies to assessments of dose to internal organs from penetrating radiation sources outside the body and from radionuclides taken into the body. Dosimetry is essential for correlating energy deposition with biological effects that are observed when living tissues are irradiated. Dose-response information provides the basis for radiation protection standards and risk assessment. Radiation interactions with living matter takes place on a microscopic scale, and the manifestation of damage may be evident at the cellular, multi-cellular, and even organ levels of biological organization. The relative biological effectiveness of ionization radiation is largely determined by the spatial distribution of energy deposition events within microscopic as well as macroscopic biological targets of interest. The spatial distribution of energy imparted is determined by the spatial distribution of radionuclides and properties of the emitted charged-particle radiation involved. The nonuniformity of energy deposition events in microscopic volumes, particularly from high linear energy transfer (LET) radiation, results in large variations in the amount of energy imparted to very small volumes or targets. Microdosimetry is the study of energy deposition events at the cellular level. Macrodosimetry is a term for conventional dose averaging at the tissue or organ level. In between is a level of dosimetry sometimes referred to as multi-cellular dosimetry. The distinction between these terms and their applications in assessment of dose from internally deposited radionuclides is described.

Fisher, D.R.

1994-06-01

189

Radiation effects in space  

SciTech Connect

As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs.

Fry, R.J.M.

1987-07-01

190

The effect of patient inhomogeneities in oesophageal 192Ir HDR brachytherapy: a Monte Carlo and analytical dosimetry study  

Microsoft Academic Search

The effect of patient inhomogeneities surrounding the oesophagus on the dosimetry planning of an upper thoracic oesophageal 192Ir HDR brachytherapy treatment is studied. The MCNPX Monte Carlo code is used for dosimetry in a patient-equivalent phantom geometry and results are compared in terms of isodose contours as well as dose volume histograms with corresponding calculations by a contemporary treatment planning

G. Anagnostopoulos; D. Baltas; E. Pantelis; P. Papagiannis; L. Sakelliou

2004-01-01

191

Dosimetry measurements using Timepix in mixed radiation fields induced by heavy ions; comparison with standard dosimetry methods  

PubMed Central

Objective of our research was to explore capabilities of Timepix for its use as a single dosemeter and LET spectrometer in mixed radiation fields created by heavy ions. We exposed it to radiation field (i) at heavy ion beams at HIMAC, Chiba, Japan, (ii) in the CERN's high-energy reference field (CERF) facility at Geneva, France/Switzerland, (iii) in the exposure room of the proton therapy laboratory at JINR, Dubna, Russia, and (iv) onboard aircraft. We compared the absolute values of dosimetric quantities obtained with Timepix and with other dosemeters and spectrometers like tissue-equivalent proportional counter (TEPC) Hawk, silicon detector Liulin, and track-etched detectors (TEDs).

Ploc, Ondrej; Kubancak, Jan; Sihver, Lembit; Uchihori, Yukio; Jakubek, Jan; Ambrozova, Iva; Molokanov, Alexander; Pinsky, Lawrence

2014-01-01

192

SU-E-J-17: A Study of Accelerator-Induced Cerenkov Radiation as a Beam Diagnostic and Dosimetry Tool  

SciTech Connect

Purpose: To investigate accelerator-induced Cerenkov radiation imaging as a possible beam diagnostic and medical dosimetry tool. Methods: Cerenkov emission produced by clinical accelerator beams in a water phantom was imaged using a camera system comprised of a high-sensitivity thermoelectrically-cooled CCD camera coupled to a large aperture (f/0.75) objective lens with 16:1 magnification. This large format lens allows a significant amount of the available Cerenkov light to be collected and focused onto the CCD camera to form the image. Preliminary images, obtained with 6 MV photon beams, used an unshielded camera mounted horizontally with the beam normal to the water surface, and confirmed the detection of Cerenkov radiation. Several improvements were subsequently made including the addition of radiation shielding around the camera, and altering of the beam and camera angles to give a more favorable geometry for Cerenkov light collection. A detailed study was then undertaken over a range of electron and photon beam energies and dose rates to investigate the possibility of using this technique for beam diagnostics and dosimetry. Results: A series of images were obtained at a fixed dose rate over a range of electron energies from 6 to 20 MeV. The location of maximum intensity was found to vary linearly with the energy of the beam. A linear relationship was also found between the light observed from a fixed point on the central axis and the dose rate for both photon and electron beams. Conclusion: We have found that the analysis of images of beam-induced Cerenkov light in a water phantom has potential for use as a beam diagnostic and medical dosimetry tool. Our future goals include the calibration of the light output in terms of radiation dose and development of a tomographic system for 3D Cerenkov imaging in water phantoms and other media.

Bateman, F; Tosh, R [NIST, Gaithersburg, MD (United States)

2014-06-01

193

A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction  

PubMed Central

It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors contributing to the recently renewed concern about the second cancer include improved cancer survival rate, younger patient population as well as emerging treatment modalities such as intensity-modulated radiation treatment (IMRT) and proton therapy that can potentially elevate secondary exposures to healthy tissues distant from the target volume. In the past 30 years, external-beam treatment technologies have evolved significantly, and a large amount of data exist but appear to be difficult to comprehend and compare. This review article aims to provide readers with an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies. Basic concepts and terminology are introduced at the beginning. That is followed by a comprehensive review of dosimetry studies for external-beam treatment modalities including classical radiation therapy, 3D-conformal x-ray therapy, intensity-modulated x-ray therapy (IMRT and tomotherapy) and proton therapy. Selected clinical data on second cancer induction among radiotherapy patients are also covered. Problems in past studies and controversial issues are discussed. The needs for future studies are presented at the end. PMID:18540047

Xu, X George; Bednarz, Bryan; Paganetti, Harald

2014-01-01

194

TOPICAL REVIEW: A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction  

NASA Astrophysics Data System (ADS)

It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors contributing to the recently renewed concern about the second cancer include improved cancer survival rate, younger patient population as well as emerging treatment modalities such as intensity-modulated radiation treatment (IMRT) and proton therapy that can potentially elevate secondary exposures to healthy tissues distant from the target volume. In the past 30 years, external-beam treatment technologies have evolved significantly, and a large amount of data exist but appear to be difficult to comprehend and compare. This review article aims to provide readers with an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies. Basic concepts and terminology are introduced at the beginning. That is followed by a comprehensive review of dosimetry studies for external-beam treatment modalities including classical radiation therapy, 3D-conformal x-ray therapy, intensity-modulated x-ray therapy (IMRT and tomotherapy) and proton therapy. Selected clinical data on second cancer induction among radiotherapy patients are also covered. Problems in past studies and controversial issues are discussed. The needs for future studies are presented at the end.

Xu, X. George; Bednarz, Bryan; Paganetti, Harald

2008-07-01

195

The [14C-N-methyl]-erythromycin breath test dosimetry complies with the French regulations for radiation safety.  

PubMed

The [14C-N-methyl]-erythromycin breath test (14C-ERMBT) is one of the most valuable probes for liver cytochrome P450-3A4 activity in humans. In order to extend the use of this test in France, we herein provide safety data regarding either patient dosimetry or worker exposure to [14C-N-methyl]-erythromycin. In order to determine the maximum radiation exposure for patient and nuclear medicine technician following one intravenous 14C-ERMBT [111 kiloBequerel (kBq)], we have used the dosimetric data gathered in animal studies and extrapolated to humans using a weight-based method, approximate data provided by the French Society of Radioprotection and erythromycin pharmacokinetics in humans, considering always the worst conditions for the patient and worker exposure determination. The radioactivity administered to a patient after one 14C-ERMBT was equal to 108.8 kBq (i.e. 98% of the total radioactivity in the 14C-erythromycin vial) leading to a patient effective dose of 20 microsievert (microSv) and a maximum effective dose after 14CO2 inhalation by the exposed worker of 16 microSv compared with a mean individual annual effective dose from natural and artificial radioactivity exposure of 3500 microSv in France. The 14C-ERMBT is safe and complies with the European regulations regarding the administration of 14C-labelled compounds in humans. It can therefore be used in clinical research in France without any particular safety requirement. PMID:12803574

Salvat, Cécile; Mouly, Stéphane; Rizzo-Padoin, Nathalie; Knellwolf, Anne-Laure; Simoneau, Guy; Duet, Michèle; Nataf, Valérie; Bailliart, Olivier; Bergmann, Jean-François

2003-06-01

196

Video-rate optical dosimetry and dynamic visualization of IMRT and VMAT treatment plans in water using Cherenkov radiation  

SciTech Connect

Purpose: A novel technique for optical dosimetry of dynamic intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. Methods: A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 (TG-119) C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a water tank doped with the fluorophore quinine sulfate. The ICCD acquisition was gated to the Linac target trigger pulse to reduce background light artifacts, read out for a single radiation pulse, and binned to a resolution of 512 × 512 pixels. The resulting videos were analyzed temporally for various regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR), and summed to obtain an overall light intensity distribution, which was compared to the expected dose distribution from the TPS using a gamma-index analysis. Results: The chosen camera settings resulted in 23.5 frames per second dosimetry videos. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.9% and 96.2% agreement between the experimentally captured Cherenkov light distribution and expected TPS dose distribution based upon a 3%/3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans, respectively. Conclusions: The results from this initial study demonstrate the first documented use of Cherenkov radiation for video-rate optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real-time nature of the acquisition, and upon future refinement may prove to be a robust and novel dosimetry method with both research and clinical applications.

Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M.; Davis, Scott C. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)] [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Zhang, Rongxiao [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)] [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Pogue, Brian W., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu [Department of Physics and Astronomy and Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Fox, Colleen J.; Gladstone, David J. [Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States)] [Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States)

2014-06-15

197

Potential of Hybrid Computational Phantoms for Retrospective Heart Dosimetry After Breast Radiation Therapy: A Feasibility Study  

SciTech Connect

Purpose: Current retrospective cardiovascular dosimetry studies are based on a representative patient or simple mathematic phantoms. Here, a process of patient modeling was developed to personalize the anatomy of the thorax and to include a heart model with coronary arteries. Methods and Materials: The patient models were hybrid computational phantoms (HCPs) with an inserted detailed heart model. A computed tomography (CT) acquisition (pseudo-CT) was derived from HCP and imported into a treatment planning system where treatment conditions were reproduced. Six current patients were selected: 3 were modeled from their CT images (A patients) and the others were modelled from 2 orthogonal radiographs (B patients). The method performance and limitation were investigated by quantitative comparison between the initial CT and the pseudo-CT, namely, the morphology and the dose calculation were compared. For the B patients, a comparison with 2 kinds of representative patients was also conducted. Finally, dose assessment was focused on the whole coronary artery tree and the left anterior descending coronary. Results: When 3-dimensional anatomic information was available, the dose calculations performed on the initial CT and the pseudo-CT were in good agreement. For the B patients, comparison of doses derived from HCP and representative patients showed that the HCP doses were either better or equivalent. In the left breast radiation therapy context and for the studied cases, coronary mean doses were at least 5-fold higher than heart mean doses. Conclusions: For retrospective dose studies, it is suggested that HCP offers a better surrogate, in terms of dose accuracy, than representative patients. The use of a detailed heart model eliminates the problem of identifying the coronaries on the patient's CT.

Moignier, Alexandra, E-mail: alexandra.moignier@irsn.fr [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)] [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France); Derreumaux, Sylvie; Broggio, David; Beurrier, Julien [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)] [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France); Chea, Michel; Boisserie, Gilbert [Groupe Hospitalier Pitie Salpetriere, Service de Radiotherapie, Paris (France)] [Groupe Hospitalier Pitie Salpetriere, Service de Radiotherapie, Paris (France); Franck, Didier; Aubert, Bernard [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)] [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France); Mazeron, Jean-Jacques [Groupe Hospitalier Pitie Salpetriere, Service de Radiotherapie, Paris (France)] [Groupe Hospitalier Pitie Salpetriere, Service de Radiotherapie, Paris (France)

2013-02-01

198

Effect of chemical composition and density of the pelvic structure in intracavitary brachytherapy dosimetry  

NASA Astrophysics Data System (ADS)

High dose rate (HDR) and low dose rate (LDR) intracavitary brachytherapies dosimetry in clinical practice are typically performed by commercial treatment planning systems. However, these systems do not fully consider the heterogeneities present in the real structure of the patient. The aim of this work is to obtain isodose curves and surfaces around the usual array of sources used in LDR ( 137Cs) and HDR ( 192Ir) intracavitary brachytherapy by Monte Carlo simulation, considering the real anatomic structure, density and chemical composition of media and tissues from the female pelvic region. The structural information was obtained from computed tomography images in the DICOM format. A voxel phantom (VP) was developed to perform ionizing radiation transport, considering the gamma spectrum of 137Cs and 192Ir. The absorbed dose was computed within each voxel of 2×2×3 mm 3. Four materials were considered in the VP—air, fat, muscle tissue and bone; however, one material per voxel was defined. Results show and quantify the effect of density and chemical composition of the medium on the absorbed dose distribution. According to them, the treatment planning systems underestimate the absorbed dose by 8% approximately for both radionuclides. In a heterogeneous medium, the absorbed dose distribution of 192Ir is more irregular than that of 137Cs but spatially better defined.

Chávez-Aguilera, N.; Torres-García, E.; Mitsoura, E.

2011-03-01

199

Dosimetry for a study of effects of 2. 45-GHz microwaves on mouse testis  

SciTech Connect

In order to determine the effects of microwave radiation on the testis, it is necessary to express the physical insult in animal studies in a way that can be replicated elsewhere and ultimately used as a basis for extrapolation to man. However, there is conflict--especially in chronic experiments--between the desire for precise dosimetry and the need to minimise alteration of the normal physiological functions of the animals. The compromise arrangement used in this study was to house the mice singly, in cages with limited food and water, and to irradiate them for up to 30 days (16 h/day) in an anechoic chamber. The only measurements taken routinely were of power density in the positions normally occupied by the cages. In addition, a series of absorption measurements was made in mouse carcasses: Whole-body specific absorption rate (SAR); energy-deposition patterns (determined thermographically); and local SAR in testis (using a miniature electric (E)-field probe). It was concluded that the SAR in testis was considerably less than the whole-body SAR. Exposure for 16 h at 50 mW/cm2 elevated rectal but not testis temperature, thus demonstrating the ability of the conscious mouse to regulate the temperature of its testis.

Cairnie, A.B.; Hill, D.A.; Assenheim, H.M.

1980-01-01

200

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

Radiation test data submitted by many testers is collated to serve as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. Total dose damage information and single event upset cross sections, i.e., the probability of a soft error (bit flip) or of a hard error (latchup) are presented.

1983-01-01

201

The UF family of reference hybrid phantoms for computational radiation dosimetry.  

PubMed

Computational human phantoms are computer models used to obtain dose distributions within the human body exposed to internal or external radiation sources. In addition, they are increasingly used to develop detector efficiencies for in vivo whole-body counters. Two classes of computational human phantoms have been widely utilized for dosimetry calculation: stylized and voxel phantoms that describe human anatomy through mathematical surface equations and 3D voxel matrices, respectively. Stylized phantoms are flexible in that changes to organ position and shape are possible given avoidance of region overlap, while voxel phantoms are typically fixed to a given patient anatomy, yet can be proportionally scaled to match individuals of larger or smaller stature, but of equivalent organ anatomy. Voxel phantoms provide much better anatomical realism as compared to stylized phantoms which are intrinsically limited by mathematical surface equations. To address the drawbacks of these phantoms, hybrid phantoms based on non-uniform rational B-spline (NURBS) surfaces have been introduced wherein anthropomorphic flexibility and anatomic realism are both preserved. Researchers at the University of Florida have introduced a series of hybrid phantoms representing the ICRP Publication 89 reference newborn, 15 year, and adult male and female. In this study, six additional phantoms are added to the UF family of hybrid phantoms-those of the reference 1 year, 5 year and 10 year child. Head and torso CT images of patients whose ages were close to the targeted ages were obtained under approved protocols. Major organs and tissues were segmented from these images using an image processing software, 3D-DOCTOR. NURBS and polygon mesh surfaces were then used to model individual organs and tissues after importing the segmented organ models to the 3D NURBS modeling software, Rhinoceros. The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference organ masses from ICRP Publication 89, (3) reference elemental compositions provided in ICRP 89 as well as ICRU Report 46, and (4) reference data on the alimentary tract organs given in ICRP Publications 89 and 100. Various adjustments and refinements to the organ systems of the previously described newborn, 15 year and adult phantoms are also presented. The UF series of hybrid phantoms retain the non-uniform scalability of stylized phantoms while maintaining the anatomical realism of patient-specific voxel phantoms with respect to organ shape, depth and inter-organ distance. While the final versions of these phantoms are in a voxelized format for radiation transport simulation, their primary format is given as NURBS and polygon mesh surfaces, thus permitting one to sculpt non-reference phantoms using the reference phantoms as an anatomic template. PMID:20019401

Lee, Choonsik; Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna; Williams, Jonathan L; Bolch, Wesley E

2010-01-21

202

Computational lymphatic node models in pediatric and adult hybrid phantoms for radiation dosimetry  

NASA Astrophysics Data System (ADS)

We developed models of lymphatic nodes for six pediatric and two adult hybrid computational phantoms to calculate the lymphatic node dose estimates from external and internal radiation exposures. We derived the number of lymphatic nodes from the recommendations in International Commission on Radiological Protection (ICRP) Publications 23 and 89 at 16 cluster locations for the lymphatic nodes: extrathoracic, cervical, thoracic (upper and lower), breast (left and right), mesentery (left and right), axillary (left and right), cubital (left and right), inguinal (left and right) and popliteal (left and right), for different ages (newborn, 1-, 5-, 10-, 15-year-old and adult). We modeled each lymphatic node within the voxel format of the hybrid phantoms by assuming that all nodes have identical size derived from published data except narrow cluster sites. The lymph nodes were generated by the following algorithm: (1) selection of the lymph node site among the 16 cluster sites; (2) random sampling of the location of the lymph node within a spherical space centered at the chosen cluster site; (3) creation of the sphere or ovoid of tissue representing the node based on lymphatic node characteristics defined in ICRP Publications 23 and 89. We created lymph nodes until the pre-defined number of lymphatic nodes at the selected cluster site was reached. This algorithm was applied to pediatric (newborn, 1-, 5-and 10-year-old male, and 15-year-old males) and adult male and female ICRP-compliant hybrid phantoms after voxelization. To assess the performance of our models for internal dosimetry, we calculated dose conversion coefficients, called S values, for selected organs and tissues with Iodine-131 distributed in six lymphatic node cluster sites using MCNPX2.6, a well validated Monte Carlo radiation transport code. Our analysis of the calculations indicates that the S values were significantly affected by the location of the lymph node clusters and that the values increased for smaller phantoms due to the shorter inter-organ distances compared to the bigger phantoms. By testing sensitivity of S values to random sampling and voxel resolution, we confirmed that the lymph node model is reasonably stable and consistent for different random samplings and voxel resolutions.

Lee, Choonsik; Lamart, Stephanie; Moroz, Brian E.

2013-03-01

203

The UF family of reference hybrid phantoms for computational radiation dosimetry  

NASA Astrophysics Data System (ADS)

Computational human phantoms are computer models used to obtain dose distributions within the human body exposed to internal or external radiation sources. In addition, they are increasingly used to develop detector efficiencies for in vivo whole-body counters. Two classes of computational human phantoms have been widely utilized for dosimetry calculation: stylized and voxel phantoms that describe human anatomy through mathematical surface equations and 3D voxel matrices, respectively. Stylized phantoms are flexible in that changes to organ position and shape are possible given avoidance of region overlap, while voxel phantoms are typically fixed to a given patient anatomy, yet can be proportionally scaled to match individuals of larger or smaller stature, but of equivalent organ anatomy. Voxel phantoms provide much better anatomical realism as compared to stylized phantoms which are intrinsically limited by mathematical surface equations. To address the drawbacks of these phantoms, hybrid phantoms based on non-uniform rational B-spline (NURBS) surfaces have been introduced wherein anthropomorphic flexibility and anatomic realism are both preserved. Researchers at the University of Florida have introduced a series of hybrid phantoms representing the ICRP Publication 89 reference newborn, 15 year, and adult male and female. In this study, six additional phantoms are added to the UF family of hybrid phantoms—those of the reference 1 year, 5 year and 10 year child. Head and torso CT images of patients whose ages were close to the targeted ages were obtained under approved protocols. Major organs and tissues were segmented from these images using an image processing software, 3D-DOCTOR™. NURBS and polygon mesh surfaces were then used to model individual organs and tissues after importing the segmented organ models to the 3D NURBS modeling software, Rhinoceros™. The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference organ masses from ICRP Publication 89, (3) reference elemental compositions provided in ICRP 89 as well as ICRU Report 46, and (4) reference data on the alimentary tract organs given in ICRP Publications 89 and 100. Various adjustments and refinements to the organ systems of the previously described newborn, 15 year and adult phantoms are also presented. The UF series of hybrid phantoms retain the non-uniform scalability of stylized phantoms while maintaining the anatomical realism of patient-specific voxel phantoms with respect to organ shape, depth and inter-organ distance. While the final versions of these phantoms are in a voxelized format for radiation transport simulation, their primary format is given as NURBS and polygon mesh surfaces, thus permitting one to sculpt non-reference phantoms using the reference phantoms as an anatomic template.

Lee, Choonsik; Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna; Williams, Jonathan L.; Bolch, Wesley E.

2010-01-01

204

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. Rev. 0 marks the first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database.

Rathbone, Bruce A.

2005-02-25

205

1988 IEEE Annual Conference on Nuclear and Space Radiation Effects, 25th, Portland, OR, July 12-15, 1988, Proceedings  

NASA Technical Reports Server (NTRS)

The effects of nuclear and space radiation on the performance of electronic devices are discussed in reviews and reports of recent investigations. Topics addressed include the basic mechanisms of radiation effects, dosimetry and energy-dependent effects, sensors in and for radiation environments, EMP/SGEMP/IEMP phenomena, radiation effects on isolation technologies, and spacecraft charging and space radiation effects. Consideration is given to device radiation effects and hardening, hardness assurance and testing techniques, IC radiation effects and hardening, and single-event phenomena.

Coakley, Peter G. (editor)

1988-01-01

206

[Genetic effects of radiation].  

PubMed

This paper is a short review of genetic effect of radiation. This includes methods and results of a large-scale genetic study on specific loci in mice and of various studies in the offspring of atomic-bomb survivors. As for the latter, there is no results obtained which suggest the effect of parental exposure to radiation. Further, in recent years, studies are conducted to the offspring born to parents who were survivors of childhood cancers. In several reports, the mean gonad dose is quite large whereas in most instances, the results do not indicate genetic effect following parental exposure to radiation. Possible reasons for the difficulties in detecting genetic effect of radiation are discussed. PMID:22514926

Nakamura, Nori

2012-03-01

207

Optically stimulated luminescence dosimetry  

Microsoft Academic Search

Models and the conceptual framework necessary for an understanding of optically stimulated luminescence (OSL) are described. Examples of various OSL readout schemes are described, along with examples of the use of OSL in radiation dosimetry.

Stephen W. S. McKeever

2001-01-01

208

Final Report Summary: Radiation dosimetry of Cu-64-labeled radiotherapy agents using PET [Positron Emission Tomography  

SciTech Connect

This project began in 1996, and was completed in July 2001. The overall goals were to compare various methods of dosimetry of PET imaging agents, as well as develop more optimal methods. One of the major accomplishments of this grant was the human PET imaging studies of a positron-emitting radiopharmaceutical for somatostatin-receptor imaging, and subsequent dosimetry calculations resulting from this study. In addition, we collaborated with Darrell Fisher and Edmund Hui to develop a MIRD-hamster program for calculating hamster organ and tumor dosimetry in hamster models. Progress was made towards a point kernel approach to more accurately determining absorbed doses to normal organs, as well as towards co-registration of PET and MRI images. This report focuses on the progress made in the last 15 months of the grant, which in general is a summary of the progress over the 5 years the project was ongoing.

Anderson, Carolyn J.; Cutler, P.D.

2002-09-01

209

Summary of radiation dosimetry results on U.S. and Soviet manned spacecraft.  

PubMed

Measurements of the radiation environment aboard U.S. and Soviet manned spacecraft are reviewed and summarized. Data obtained mostly from passive and some active radiation detectors now exist for the case of low Earth-orbit missions. Major uncertainties still exist for space exposure in high altitude, high inclination, geostationary orbits, in connection with solar effects and that of shielding. Data from active detectors flown in Spacelabs 1 and 2 suggest that a variety of phenomena must be understood before the effects of long-term exposure at the space-station type of orbit and shielding can be properly assessed. PMID:11537239

Benton, E V

1986-01-01

210

1991 IEEE Annual Conference on Nuclear and Space Radiation Effects, 28th, San Diego, CA, July 15-19, 1991, Proceedings  

NASA Technical Reports Server (NTRS)

Various papers on nuclear science are presented. The general topics addressed are: basic mechanisms of radiation effects, dosimetry and energy-dependent effects, isolation technologies, device radiation response and hardening, microcircuit radiation response and hardening, single-event phenomena, hardness assurance and testing techniques, spacecraft charging, space environments and effects.

Millward, Douglas G. (editor)

1991-01-01

211

Radiation Effects In Space  

SciTech Connect

Protecting space missions from severe exposures from radiation, in general, and long duration/deep space human missions, in particular, is a critical design driver, and could be a limiting factor. The space radiation environment consists of galactic cosmic rays (GCR), solar particle events (SPE), trapped radiation, and includes ions of all the known elements over a very broad energy range. These ions penetrate spacecraft materials producing nuclear fragments and secondary particles that damage biological tissues and microelectronic devices. One is required to know how every element (and all isotopes of each element) in the periodic table interacts and fragments on every other element in the same table as a function of kinetic energy ranging over many decades. In addition, the accuracy of the input information and database, in general and nuclear data in particular, impacts radiation exposure health assessments and payload penalty. After a brief review of effects of space radiation on materials and electronics, human space missions to Mars is discussed.

Tripathi, Ram K. [NASA Langley Research Center, MS - 188 E, Hampton VA 23681 (United States)

2011-06-01

212

The 15-Country Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry: study of errors in dosimetry.  

PubMed

To provide direct estimates of cancer risk after low-dose protracted exposure to ionizing radiation, a large-scale epidemiological study of nuclear industry workers was conducted in 15 countries. As part of this study, identification and quantification of errors in historical recorded doses was conducted based on a review of dosimetric practices and technologies in participating facilities. The main sources of errors on doses from "high-energy" photons (100-3000 keV) were identified as the response of dosimeters in workplace exposure conditions and historical calibration practices. Errors related to dosimetry technology and radiation fields were quantified to derive period- and facility-specific estimates of bias and uncertainties in recorded doses. This was based on (1) an evaluation of predominant workplace radiation from measurement studies and dosimetry expert assessment and (2) an estimation of the energy and geometry response of dosimeters used historically in study facilities. Coefficients were derived to convert recorded doses to H(p) (10) and organ dose, taking into account different aspects of the calibration procedures. A parametric, lognormal error structure model was developed to describe errors in doses as a function of facility and time period. Doses from other radiation types, particularly neutrons and radionuclide intake, could not be adequately reconstructed in the framework of the 15-Country Study. Workers with substantial doses from these radiation types were therefore identified and excluded from analyses. Doses from "lower-energy" photons (<100 keV) and from "higher-energy" photons (>3 MeV) were estimated to be small. PMID:17388692

Thierry-Chef, I; Marshall, M; Fix, J J; Bermann, F; Gilbert, E S; Hacker, C; Heinmiller, B; Murray, W; Pearce, M S; Utterback, D; Bernar, K; Deboodt, P; Eklof, M; Griciene, B; Holan, K; Hyvonen, H; Kerekes, A; Lee, M-C; Moser, M; Pernicka, F; Cardis, E

2007-04-01

213

Evaluation of The Combined Effects of Hyperthermia, Cobalt-60 Gamma Rays and IUdR on Cultured Glioblastoma Spheroid Cells and Dosimetry Using TLD-100  

PubMed Central

Objective In radiation treatment, the irradiation which is effective enough to control the tumors far exceeds normal-tissues tolerance. Thus to avoid such unfavourable outcomes, some methods sensitizing the tumor cells to radiation are used. Iododeoxyuridine (IUdR) is a halogenated thymidine analogue that known to be effective as a radiosensitizer in human cancer therapy. Improving the potential efficacy of radiation therapy after combining to hyperthermia depends on the magnitude of the differential sensitization of the hyperthermic effects or on the differential cytotoxicity of the radiation effects on the tumor cells. In this study, we evaluated the combined effects of IUdR, hyperthermia and gamma rays of 60Co on human glioblastoma spheroids culture. Materials and Methods In this experimental study,the cultured spheroids with 100µm diameter were treated by 1 µM IUdR, 43°C hyperthermia for an hour and 2 Gy gamma rays, respectively. The DNA damages induced in cells were compared using alkaline comet assay method, and dosimetry was then performed by TLD-100. Comet scores were calculated as mean ± standard error of mean (SEM) using one-way ANOVA. Results Comparison of DNA damages induced by IUdR and hyperthermia + gamma treatment showed 2.67- and 1.92-fold enhancement, respectively, as compared to the damages induced by radiation alone or radiation combined IUdR. Dosimetry results showed the accurate dose delivered to cells. Conclusion Analysis of the comet tail moments of spheroids showed that the radiation treatments combined with hyperthermia and IUdR caused significant radiosensitization when compared to related results of irradiation alone or of irradiation with IUdR. These results suggest a potential clinical advantage of combining radiation with hyperthermia and indicate effectiveness of hyperthermia treatment in inducing cytotoxicity of tumor cells. PMID:24611138

Neshasteh-Riz, Ali; Rahdani, Rozhin; Mostaar, Ahmad

2014-01-01

214

Water calorimetry-based radiation dosimetry in iridium-192 brachytherapy and proton therapy  

NASA Astrophysics Data System (ADS)

The aim of this work is to develop and evaluate a primary standard for HDR 192Ir brachytherapy sources as well as for active spot scanning proton radiotherapy beams based on stagnant 4 °C water calorimetry. The measurements were performed using an in-house built water calorimeter and a parallel-plate calorimeter vessel. The dose measurement results of the McGill calorimeter were validated in high energy photon beams against Canada's national established primary standard at the NRC. The measurements in brachytherapy were performed with a spring-loaded catheter holder which allowed for the 192Ir source to come directly inside the water calorimeter. The COMSOL MULTIPHYSICS(TM) software was used to solve the heat transport equation numerically for a detailed geometrical model of our experimental setup. In brachytherapy, reference dosimetry protocols were also developed and used to measure the dose to water directly using thimble type ionization chambers and Gafchromic films with traceable 60Co (or higher energy photons) calibration factor. Based on water calorimetry standard, we measured an absolute dose rate to water of 361+/-7 microGy/(h·U) at 55 mm source-to-detector separation. The 1.9 % uncertainty on water calorimetry results is in contrast with the current recommended AAPM TG-43 protocol that achieves at best an uncertainty (k=1) of 2.5 % based on an indirect dose to water measurement technique. All measurement results from water calorimetry, ion chamber, film, and TG-43 agreed to within 0.83 %. We achieved an overall dose uncertainty of 0.4 % and 0.6 % for scattered and scanned proton radiation water calorimetry, respectively. The water calorimetry absorbed dose to water results agreed with those obtained through the currently recommended IAEA TRS-398 protocol (measurements made using an ionization chamber with a 60Co calibration factor) to better than 0.14 % and 0.32 % in scattered and scanned proton beams, respectively. In conclusion, this work forms the foundation for a primary standard in 192Ir brachytherapy and scanning proton radiotherapy using water calorimetry. Not only have we been able to directly and absolute measure the absorbed dose to water, but the uncertainties of dose results over the current accepted protocols have been improved dramatically.

Sarfehnia, Arman

215

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

This databank is the collation of radiation test data submitted by many testers and serves as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. It contains radiation sensitivity results from ground tests and is divided into two sections. Section A lists total dose damage information, and section B lists single event upset cross sections, I.E., the probability of a soft error (bit flip) or of a hard error (latchup).

1983-01-01

216

Impacts of LIS technology on internal dosimetry  

Microsoft Academic Search

The Laser Isotope Separation (LIS) process has some undesirable side effects that are detrimental to present methods of internal dosimetry. This report concludes: (1) the LIS process will result in the loss of the americium-241 ''tag'' that is used to assess internal depositions of plutonium from measurements of americium-241 radiations, thereby increasing the detection limit of plutonium in the lung

L. G. Faust; L. W. Brackenbush

1986-01-01

217

Cell specific radiation dosimetry in skeleton from life-span carcinogenesis studies  

SciTech Connect

The osteogenic sarcoma is the dominant life-threatening pathology in lifespan studies of beagles exposed to alpha-emitting bone-seeking radionuclides. It was deduced from these studies that certain skeletal sites are more prone to develop tumors. This project sought to determine the bone cells at risk and their cell-specific radiation dose. The cell-specific radiation dose values are related to loss and high Ra-226 and Pu-239 induced osteogenic sarcoma sites, to test different dose response hypothesis and predict the extent of effects in humans.

Webster, S.S.J.

1993-04-05

218

Cell specific radiation dosimetry in skeleton from life-span carcinogenesis studies. Final report  

SciTech Connect

The osteogenic sarcoma is the dominant life-threatening pathology in lifespan studies of beagles exposed to alpha-emitting bone-seeking radionuclides. It was deduced from these studies that certain skeletal sites are more prone to develop tumors. This project sought to determine the bone cells at risk and their cell-specific radiation dose. The cell-specific radiation dose values are related to loss and high Ra-226 and Pu-239 induced osteogenic sarcoma sites, to test different dose response hypothesis and predict the extent of effects in humans.

Webster, S.S.J.

1993-04-05

219

Study on application of PTFE, FEP and PFA fluoropolymers on radiation dosimetry  

NASA Astrophysics Data System (ADS)

Changes induced by radiation in the UV-vis and Infrared absorbance spectra of fluoropolymer films were investigated. Samples (3×1 cm 2) of commercially available fluoropolymers, tetrafluoropolymer homopolymer (PTFE-Tecnofluor/DuPont) and its copolymers with hexafluoropropylene (FEP 1000 C-DuPont) and perfluoroalkoxy (PFA 500 CLP-Dupont) were irradiated with 60Co gamma radiation in free air at electronic equilibrium conditions with absorbed doses between 1 and 150 kGy. Studies of environmental condition effects, such as temperature and light, pre- and post-irradiation stability and dose range useful response were carried out. Fluoropolymers are very stable when exposed to different ambient conditions; the dosimetric wavelength is characteristic for each type of fluoropolymer and a linear correlation was found between gamma radiation dose and optical response.

Galante, A. M. S.; Galante, O. L.; Campos, L. L.

2010-07-01

220

Estimating the effective density of engineered nanomaterials for in vitro dosimetry  

PubMed Central

The need for accurate in vitro dosimetry remains a major obstacle to the development of cost-effective toxicological screening methods for engineered nanomaterials. An important key to accurate in vitro dosimetry is the characterization of sedimentation and diffusion rates of nanoparticles suspended in culture media, which largely depend upon the effective density and diameter of formed agglomerates in suspension. Here we present a rapid and inexpensive method for accurately measuring the effective density of nano-agglomerates in suspension. This novel method is based on the volume of the pellet obtained by bench-top centrifugation of nanomaterial suspensions in a packed cell volume tube, and is validated against gold-standard analytical ultracentrifugation data. This simple and cost-effective method allows nanotoxicologists to correctly model nanoparticle transport, and thus attain accurate dosimetry in cell culture systems, which will greatly advance the development of reliable and efficient methods for toxicological testing and investigation of nano-bio interactions in vitro. PMID:24675174

DeLoid, Glen; Cohen, Joel M.; Darrah, Tom; Derk, Raymond; Wang, Liying; Pyrgiotakis, Georgios; Wohlleben, Wendel; Demokritou, Philip

2014-01-01

221

Phys. Med. Biol. 45 (2000) 18631868. Printed in the UK PII: S0031-9155(00)10622-0 Ultraviolet radiation dosimetry with radiochromic film  

E-print Network

-mail: mbutson@usa.net Received 4 January 2000, in final form 29 March 2000 Abstract. Radiochromic film is tested radiation dosimetry with radiochromic film Martin J Butson¶, Tsang Cheung, Peter K N Yu, Donna Abbati, NSW 2500, Australia § Wollongong Hospital, Department of Nuclear Medicine, Crown Street, Wollongong

Yu, K.N.

222

DEVELOPMENTS AND TRENDS IN BIOEQUIVALENT DOSIMETRY.  

PubMed

Significant progress in radiobiology has refined the understanding of radiation-induced biological response at the cellular level and challenged the conventional application of a macroscopic description of radiation action to dosimetry in favour of a microscopic approach. Pioneering experiments, which investigated the stochastics of energy deposition from ionising radiations in volumes of cellular dimensions, contributed to the recognition of microdosimetry as a new scientific discipline. The first quantitative applications of Monte Carlo track structure simulations in radiobiology, however, supported evidence for target sizes of particular biological importance being in the nanometre regime. Bioequivalent dosimetry attempts to link particular features of the response of physical detectors with biological endpoints, exploiting clusters of multiple ionisations within nanometre scales in solid-state, gas- and water-filled devices. This approach supports the continued development of new concepts and quantities in radiation protection to permit evaluation of the biological effectiveness of radiations of different quality independently of dose and dose rate. PMID:25183836

Hajek, M

2014-09-01

223

Application of fission track detectors to californium-252 neutron dosimetry in tissue near the radiation source  

Microsoft Academic Search

Fission track detectors were applied to a unique problem in neutron dosimetry. Measurements of neutron doses were required at locations within a tumor of 1 cm diameter implanted on the back of a mouse and surrounded by a square array of four ²⁵²Cf medical sources. Measurements made in a tissue-equivalent mouse phantom showed that the neutron dose rate to the

Richard A. Oswald; L. H. Lanzl; M. Rozenfeld

1981-01-01

224

Cancer risk among atomic bomb survivors. The RERF Life Span Study. Radiation Effects Research Foundation  

Microsoft Academic Search

This article summarizes the risk of cancer among the survivors of the atomic bombing of Hiroshima and Nagasaki. We focus primarily on the risk of death from cancer among individuals in the Life Span Study sample of the Radiation Effects Research Foundation from 1950 through 1985 based on recently revised dosimetry procedures. We report the risk of cancer other than

Y. Shimizu; W. J. Schull; H. Kato

1990-01-01

225

Response of the alanine/ESR dosimetry system to MV x-rays relative to 60Co radiation  

NASA Astrophysics Data System (ADS)

The measurand relevant in dosimetry for radiation therapy is the absorbed dose to water, DW. The Physikalisch-Technische Bundesanstalt (PTB) has established a secondary standard for DW for high-energy photon and electron radiation based on electron spin resonance (ESR) of the amino acid alanine. Since the calibration is usually performed using 60Co radiation while a huge part of the external radiation therapy is done with high-energy x-rays from linear accelerators, determination of the response is an important issue. The results presented in this paper are the most accurate ones available today with uncertainties assigned to the relative response for 8 MV and 16 MV of the order of 0.3%. The experimental results are compared to Monte Carlo simulations using the EGSnrc software package. In the appendix, it is demonstrated how mean values from repetitive irradiations and their uncertainties are obtained in a consistent way using Bayesian statistics, even in the presence of at first sight inconsistent data. It is important to note that the formulae derived to obtain the final results follow from first principles, without recurring to ad hoc solutions or simple recipes and are valid for all kinds of repetitive measurements.

Anton, Mathias; Kapsch, Ralf-Peter; Krystek, Michael; Renner, Franziska

2008-05-01

226

Historical review of personnel dosimetry development and its use in radiation protection programs at Hanford 1944 to the 1980s  

SciTech Connect

This document is an account of the personnel dosimetry programs as they were developed and practiced at Hanford from their inception in 1943 to 1944 to the 1980s. This history is divided into sections covering the general categories of external and internal measurement methods, in vivo counting, radiation exposure recordkeeping, and calibration of personnel dosimeters. The reasons and circumstances surrounding the inception of these programs at Hanford are discussed. Information about these programs was obtained from documents, letters, and memos that are available in our historical records; the personnel files of many people who participated in these programs; and from the recollections of many long-time, current, and past Hanford employees. For the most part, the history of these programs is presented chronologically to relate their development and use in routine Hanford operations. 131 refs., 38 figs., 23 tabs.

Wilson, R.H.

1987-02-01

227

A review of the use and potential of the GATE Monte Carlo simulation code for radiation therapy and dosimetry applications  

SciTech Connect

In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same frameworkis emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.

Sarrut, David, E-mail: david.sarrut@creatis.insa-lyon.fr [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon (France) [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon (France); Université Lyon 1 (France); Centre Léon Bérard (France)] [France; Bardiès, Manuel; Marcatili, Sara; Mauxion, Thibault [Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse (France)] [Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse (France); Boussion, Nicolas [INSERM, UMR 1101, LaTIM, CHU Morvan, 29609 Brest (France)] [INSERM, UMR 1101, LaTIM, CHU Morvan, 29609 Brest (France); Freud, Nicolas; Létang, Jean-Michel [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon (France)] [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon (France); Jan, Sébastien [CEA/DSV/I2BM/SHFJ, Orsay 91401 (France)] [CEA/DSV/I2BM/SHFJ, Orsay 91401 (France); Loudos, George [Department of Medical Instruments Technology, Technological Educational Institute of Athens, Athens 12210 (Greece)] [Department of Medical Instruments Technology, Technological Educational Institute of Athens, Athens 12210 (Greece); Maigne, Lydia; Perrot, Yann [UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière (France)] [UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière (France); Papadimitroulas, Panagiotis [Department of Biomedical Engineering, Technological Educational Institute of Athens, 12210, Athens (Greece)] [Department of Biomedical Engineering, Technological Educational Institute of Athens, 12210, Athens (Greece); Pietrzyk, Uwe [Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany and Fachbereich für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal (Germany)] [Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany and Fachbereich für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal (Germany); Robert, Charlotte [IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, Orsay 91406 (France)] [IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, Orsay 91406 (France); and others

2014-06-15

228

1992 IEEE Annual Conference on Nuclear and Space Radiation Effects, 29th, New Orleans, LA, July 13-17, 1992, Proceedings  

NASA Technical Reports Server (NTRS)

The papers presented in this volume provide an overview of recent theoretical and experimental research related to nuclear and space radiation effects. Topics dicussed include single event phenomena, radiation effects in particle detectors and associated electronics for accelerators, spacecraft charging, and space environments and effects. The discussion also covers hardness assurance and testing techniques, electromagnetic effects, radiation effects in devices and integrated circuits, dosimetry and radiation facilities, isolation techniques, and basic mechanisms.

Van Vonno, Nick W. (editor)

1992-01-01

229

US plant and radiation dosimetry experiments flown on the soviet satellite COSMOS 1129. Final report  

SciTech Connect

Experiments included: 30 young male Wistar SPF rats used for wide range physiological studies Kosmos Satellites experiments with plants, fungi, insects, and mammalian tissue cultures; radiation physics experiments; a heat convection study; a rat embryology experiment in which an attempt was made to breed 2 male and 5 female rats during the flight; and fertile quail eggs used to determine the effects of spaceflight on avian embryogenesis. Specimens for US experiments were initially prepared at the recovery site or in Moscow and transferred to US laboratories for complete analyses. An overview of the mission focusing on preflight, on orbit, and postflight activities pertinent to the fourteen US experiments aboard Cosmos 1129 is presented.

Heinrich, M.R.; Souza, K.A.

1981-05-01

230

US plant and radiation dosimetry experiments flown on the Soviet satellite Cosmos 1129  

NASA Technical Reports Server (NTRS)

Experiments included: 30 young male Wistar SPF rats used for wide range physiological studies; experiments with plants, fungi, insects, and mammalian tissue cultures; radiation physics experiments; a heat convection study; a rat embryology experiment in which an attempt was made to breed 2 male and 5 female rats during the flight; and fertile quail eggs used to determine the effects of spaceflight on avian embryogenesis. Specimens for US experiments were initially prepared at the recovery site or in Moscow and transferred to US laboratories for complete analyses. An overview of the mission focusing on preflight, on orbit, and postflight activities pertinent to the fourteen US experiments aboard Cosmos 1129 is presented.

Heinrich, M. R. (editor); Souza, K. A. (editor)

1981-01-01

231

Preclinical animal research on therapy dosimetry with dual isotopes  

Microsoft Academic Search

Preclinical research into radionuclide therapies based on radiation dosimetry will enable the use of any LET-equivalent radionuclide.\\u000a Radiation dose and dose rate have significant influence on dose effects in the tumour depending on its radiation sensitivity,\\u000a possibilities for repair of sublethal damage, and repopulation during or after the therapy. Models for radiation response\\u000a of preclinical tumour models after peptide receptor

Mark W. Konijnenberg; Marion de Jong

2011-01-01

232

Radiation effect on implanted pacemakers  

SciTech Connect

It was previously thought that diagnostic or therapeutic ionizing radiation did not have an adverse effect on the function of cardiac pacemakers. Recently, however, some authors have reported damaging effect of therapeutic radiation on cardiac pulse generators. An analysis of a recently-extracted pacemaker documented the effect of radiation on the pacemaker pulse generator.

Pourhamidi, A.H.

1983-10-01

233

Cosmic Ray Dosimetry  

NASA Astrophysics Data System (ADS)

Radiation levels at aircraft cruising altitudes are twenty times higher than at sea level. Thus, on average, a typical airline pilot receives a larger annual radiation dose than some one working in nuclear industry. The main source of this radiation is from galactic cosmic radiation, high energy particles generated by exploding stars within our own galaxy. In this work we study cosmic rays dosimetry at various aviation altitudes using the PARMA model.

Si Belkhir, F.; Attallah, R.

2010-10-01

234

Dosimetry of He-Ne laser radiation on specimens of human tympanic membrane  

NASA Astrophysics Data System (ADS)

The clinical application of a laser-Doppler-vibrometry for recording the motion of the tympanic membrane is relying on the harmlessness of the used He-Ne-laser beam. Even when the daily experience tells that an intensity of 1 mW focused onto the skin introduces no obvious thermal effects, focusing this beam down to a waist of a diameter of 40 micrometers , as it is done in this case, raises up the density of power to 80 W/cm2. Safety rules postulate a maximum radiation time at this density of less than 10 ms sec, which is much too short to perform any measurement. Therefore the threshold and the degree of thermal effects have been investigated histomorphologically.

Foth, Hans-Jochen; Huthoff, Christian; Gauer, Axel; Baker, Antonio; Stasche, Norbert; Hoermann, Karl

1994-02-01

235

Image-based dosimetry for selective internal radiation therapy (SIRT) using yttrium-90 microspheres  

NASA Astrophysics Data System (ADS)

90Y-loaded microspheres are currently used as a palliative treatment for patients with primary and metastatic solid liver tumors. These microspheres contain radioactive 90Y, which decays via beta-minus transition to 90Zr. While the normal liver receives about 75% of its blood supply from the portal vein, hepatic tumors receive their blood supply almost exclusively from the hepatic artery. Taking advantage of this unique blood flow, radioactive microspheres are injected into the hepatic artery resulting in a preferential distribution to tumor sites within the liver. Studies show that the single best prognostic indicator for patient response is the tumor-to-normal tissue (T:N) activity uptake ratio. However, 90Y emits very few photons its broad bremsstrahlung spectrum leads to diffuse, low resolution images, which are insufficient for accurate T:N quantification. Thus, the first objective was to develop a PET-labeled microsphere as a surrogate for the therapeutic microsphere to provide accurate biodistribution information. Furthermore, patient outcome is also suspected to be linked to the mean tumor dose and tumor dose volume histogram. Therefore, a second objective was to develop and validate a method to calculate the dose distribution within the tumor and normal liver tissue. Computer software that generates three-dimensional (3D) dose distributions was validated by comparing results to experimental measurements. The novel development of a 3D gel dosimeter will be discussed as well as a new protocol for 2D film dosimetry. Both dosimetry methods were validated but only film provided the desired accuracy. The overall accuracy of the dose distribution depends on the uncertainty of the 90Y assay, which can extend to 15% at 1sigma. Therefore, the third objective was to develop an accurate non-destructive assay of 90Y. To this end, a new 90Y positron branching ratio was measured and a clinically relevant transfer standard was developed. In summation, this thesis will present a new PET-labeled microsphere for pre- and post-treatment assessment, two new beta dosimetry protocols along with validation studies, a new positron branching ratio for 90Y that led to formation of an accurate non-destructive assay, and the first successful experimental validation of a computer generated internal dose distribution using dose kernel convolution.

Selwyn, Reed G.

236

Spallation radiation damage and dosimetry for accelerator transmutation of waste applications  

SciTech Connect

Proposals are currently being made for systems to treat radioactive waste based on the use of accelerator-driven neutron sources. A linear proton accelerator with energies as high as 1600 MeV and currents up to 250 ma are anticipated for the driver. The neutron fluxes may reach up to 10{sup 20} neutrons/m{sup 2}s as generated by the spallation reactions that occur when the protons strike target materials. Calculations are described to determine radiation fluxes and flux spectra inherent in such systems and to estimate likely radiation effects on system components. The calculations use LAHET, a Monte Carlo high-energy transport code, and MCNP, a generalized-geometry, coupled neutron-photon Monte Carlo transport code. Cross sections for displacement and helium production are presented for spallation neutrons of energies from 21 MeV to 1600 MeV for Inconel 718 (Ni plus 18.5, 18.5, 5.1, and 3 wt % of Cr, Fe, Nb, and Mo, respectively), an alloy that is used for the proton beam entry window in several accelerators. In addition, results for this alloy are presented for the primary knocked-on atom (PKA) spectrum and the transmutation yield for 1600 MeV incident neutrons.

Wechsler, M.S.; Lin, C. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering; Ferguson, P.D. [Missouri Univ., Rolla, MO (United States). Dept. of Nuclear Engineering; Sommer, W.F. [Los Alamos National Lab., NM (United States)

1993-10-01

237

Ultraviolet radiation (UVR) dosimetry system and the use of Ge-doped silica optical fibres  

NASA Astrophysics Data System (ADS)

Previous studies have shown that over exposure to ultraviolet radiation (UVR), either from sunlight or artificial sources, can cause severe biological effects including cataracts, photokeratitis and skin cancer. In this respect, there exists the need to introduce a sensitive UV dosimetric material capable of measuring radiation dose to high accuracy in order to deliver UVR safely and efficiently. Present study has focussed on the investigation of the potential thermoluminescent (TL) sensitivity of commercially available germanium (Ge)-doped silica (SiO2) optical fibres subjected to UVR. The main interest of this study is to find out whether these doped SiO2 optical fibres can be used as a sensible integrator of environmental UV exposures. In the present study, commercially available Ge-doped SiO2 optical fibres have been used with a core diameter of 11 ?m (CorActive, Canada), 23 ?m (Central Glass and Ceramic Research Institute Kolkata, India) and 50 ?m (Central Glass and Ceramic Research Institute Kolkata, India) and a cladding diameter of 125±0.1 ?m, irradiated over a wide range of UV dose. Results have shown that these fibres exhibit a linear dose response (with correlation coefficient better than 0.9852). The 50 ?m fibre produces greater TL response than that obtained for 11- and 23 ?m fibres. The TL results are compared with that of the well-established TL dosimeter material lithium fluoride.

Abdul Rahman, Ahmad Taufek; Abu Bakar, Noor Khairunnisa; Chandra Paul, Mukul; Bradley, D. A.

2014-11-01

238

Optically stimulated luminescence in LiF:Mg,Ti: Application to solid-state radiation dosimetry  

NASA Astrophysics Data System (ADS)

The effects of various experimental parameters have been investigated in order to optimize potential dosimetric applications of optically stimulated luminescence from LiF:Mg,Ti. These included: (i) the most appropriate filter in the emission channel for optimization of signal to noise ratio, (ii) the effect of sample thickness and self-absorption, (iii) the effects of high dose pre-irradiation for sensitization/radiation damage on the emission spectra and (iv) the effects of the preirradiation annealing/cooling procedures. Two methods have been used to measure the time-stability of the F3+ and F2 emission bands: (i) via the measurement of the OSL intensity (520 or 640 nm band) as a function of the laser illumination time and (ii) via the measurement of the emission spectra in the range 500-700 nm after 30 min illumination by 300 mW laser light (457 nm). In addition the OSL dependence on the stimulation light intensity has also been investigated.

Oster, L.; Druzhyna, S.; Horowitz, Y. S.

2011-08-01

239

"Mir" radiation dosimetry results during the solar proton events in September-October 1989.  

PubMed

Using data from dosimetry-radiometry system "Liulin" on board of "Mir"-space station the particle flux and doserate during September-October, 1989 has been studied. The orbit of the station was 379 km perigee, 410 km apogee and 51.6 degrees inclination. Special attention has been paid to the flux and doserate changes inside the station after intensive solar proton events (SPE) on 29 of September, 1989. The comparison between the doses before and after the solar flares shows increase of the calculated mean dose per day by factor of 10 to 200. During the SPE on the 29 of September the additional dose was 310 mrad. The results of the experiment are compared with the data for the solar proton fluxes obtained on the GOES-7 satellite. PMID:11537022

Dachev TsP; Matviichuk YuN; Bankov, N G; Semkova, J V; Koleva, R T; Ivanov YaJ; Tomov, B T; Petrov, V M; Shurshakov, V A; Bengin, V V; Machmutov, V S; Panova, N A; Kostereva, T A; Temny, V V; Ponomarev YuN; Tykva, R

1992-01-01

240

ESTIMATING SOLAR RADIATION EXPOSURE IN WETLANDS USING RADIATION MODELS, FIELD DATA, AND GEOGRAPHIC INFORMATION SYSTEMS  

EPA Science Inventory

This seminar will describe development of methods for the estimation of solar radiation doses in wetlands. The methodology presents a novel approach to incorporating aspects of solar radiation dosimetry that have historically received limited attention. These include effects of a...

241

Taurine for EPR dosimetry.  

PubMed

EPR dosimetry is characterized by its non-destructive read-out and the possibility of dose archival. Here, taurine is proposed as a radiation dosimeter using EPR spectroscopy. The EPR spectrum of taurine was studied and assigned, and changes in the taurine EPR spectrum as a result of the change in both modulation amplitude and microwave power were quantified. For gamma radiation, the energy absorption coefficient and the collision mass stopping power of taurine were compared to the corresponding values of soft tissue and alanine, in addition to calculation of effective atomic numbers. The response of taurine to gamma radiation doses in the range from 0.1 to 50 kGy was investigated, as well as that in the range from 1.0 to 20.0 Gy using numerically enhanced EPR taurine spectra. Both response curves showed a linear behavior. In addition, the time dependence of radiation-induced radicals was studied for short (during the first 6 h after irradiation) and long (during about 3 months after irradiation) time periods, and a reasonable degree of stability of the taurine radicals was observed. It is concluded that taurine is a promising dosimeter, which is characterized by its simple spectrum, radical stability, and wide range of linear response to gamma radiation. PMID:22526915

Maghraby, A; Mansour, A; Tarek, E

2012-08-01

242

Unruh radiation and Interference effect  

E-print Network

A uniformly accelerated charged particle feels the vacuum as thermally excited and fluctuates around the classical trajectory. Then we may expect additional radiation besides the Larmor radiation. It is called Unruh radiation. In this report, we review the calculation of the Unruh radiation with an emphasis on the interference effect between the vacuum fluctuation and the radiation from the fluctuating motion. Our calculation is based on a stochastic treatment of the particle under a uniform acceleration. The basics of the stochastic equation are reviewed in another report in the same proceeding. In this report, we mainly discuss the radiation and the interference effect.

Satoshi Iso; Yasuhiro Yamamoto; Sen Zhang

2011-02-23

243

Correction-less dosimetry of nonstandard photon fields: a new criterion to determine the usability of radiation detectors  

NASA Astrophysics Data System (ADS)

In the IAEA-AAPM dosimetry formalism, detector measurements in general nonstandard conditions are corrected using the factor k_{{{Q}_{\\text{clin}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{clin}}},{{f}_{\\text{msr}}}} . This factor needs to be evaluated on a case-by-case basis which is difficult to accomplish in practice. The present paper aims to provide a method that allows neglecting correction factors for small and composite IMRT fields by first determining a radiation detector’s usability in these fields. Detailed models of nine radiation detectors are built: four ionization chambers (NE2571, A12, A1SL, A14), three small field detectors (PTW31018 microLion, PTW60003 natural diamond, PTW60012 unshielded diode) and two near water-equivalent detectors (alanine, W1 scintillating fiber). Using the egs_chamber Monte Carlo code, dose response functions at 6 MV and 25 MV are sampled for each detector and their corresponding volume of water. These functions are then used with a newly derived criterion to evaluate an upper bound \\xi _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} on the variable \\epsilon _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} if no field collimation/modulation occurs over a given perturbation zone. The variable \\epsilon _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} is defined as the absolute value of the relative deviation from unity of a nonstandard field quality correction factor k_{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} . Using the same criterion, perturbation zones are evaluated by finding the smallest field size allowed for correction-less dosimetry with a given tolerance \\xi _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} . For composite fields, the sensitivity of detectors to the non-uniformity of virtual symmetric collapsed beams over regions of interest specified by the criterion is studied to estimate an upper bound \\tilde{\\xi}_{{{Q}_{\\text{ns}}},Q}^{{{f}_{\\text{ns}}},{{f}_{\\text{ref}}}} on \\epsilon _{{{Q}_{\\text{ns}}},Q}^{{{f}_{\\text{ns}}},{{f}_{\\text{ref}}}} for a given beam flatness. Finally, a newly defined perturbation function is used to minimize the perturbations of the microLion chamber through density compensation. The theoretical criterion shows good agreement with full Monte Carlo simulations of \\epsilon _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} . Perturbation zones are shown to be sensitive to both the energy of the beam and the orientation of the detector. The density-compensated microLion shows significantly improved response in both axial and radial orientations in small and composite IMRT fields. Finally, the new Exradin W1 scintillator is shown to have \\xi _{{{Q}_{\\text{ns}}},{{Q}_{\\text{msr}}}}^{{{f}_{\\text{ns}}},{{f}_{\\text{msr}}}} values under 1% in small fields. The methods presented in this work theoretically show that correction-less dosimetry of nonstandard field can be accomplished by knowing the limit of usability of radiation detectors in these conditions. Potential applications include small field output factor measurements and absolute absorbed dose to water verification in the QA of clinical IMRT fields.

Kamio, Y.; Bouchard, H.

2014-09-01

244

Jaw Dysfunction Related to Pterygoid and Masseter Muscle Dosimetry After Radiation Therapy in Children and Young Adults With Head-and-Neck Sarcomas  

SciTech Connect

Purpose: To investigate the relationship between jaw function, patient and treatment variables, and radiation dosimetry of the mandibular muscles and joints in children and young adults receiving radiation for soft-tissue and bone sarcomas. Methods and Materials: Twenty-four pediatric and young adult patients with head-and-neck sarcomas were treated on an institutional review board-approved prospective study of focal radiation therapy for local tumor control. Serial jaw depression measurements were related to radiation dosimetry delivered to the medial and lateral pterygoid muscles, masseter muscles, and temporomandibular joints to generate mathematical models of jaw function. Results: Baseline jaw depression was only influenced by the degree of surgical resection. In the first 12 weeks from initiation of radiation, surgical procedures greater than a biopsy, administration of cyclophosphamide containing chemotherapy regimes, and large gross tumor volumes adversely affected jaw depression. Increasing dose to the pterygoid and masseter muscles above 40 Gy predicted loss of jaw function over the full course of follow-up. Conclusions: Clinical and treatment factors are related to initial and subsequent jaw dysfunction. Understanding these complex interactions and the affect of specific radiation doses may help reduce the risk for jaw dysfunction in future children and young adults undergoing radiation therapy for the management of soft-tissue and bone sarcomas.

Krasin, Matthew J., E-mail: matthew.krasin@stjude.org [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN (United States); Wiese, Kristin M. [Department of Rehabilitation Services, St. Jude Children's Research Hospital, Memphis, TN (United States); Spunt, Sheri L. [Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Department of Pediatrics, University of Tennessee College of Medicine, Memphis, TN (United States); Hua, Chia-ho [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN (United States); Daw, Najat [Department of Pediatrics, University of Tennessee College of Medicine, Memphis, TN (United States); Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Navid, Fariba [Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Department of Pediatrics, University of Tennessee College of Medicine, Memphis, TN (United States); Davidoff, Andrew M. [Department of Surgery, St. Jude Children's Research Hospital, Memphis, TN (United States); Department of Surgery, University of Tennessee College of Medicine, Memphis, TN (United States); McGregor, Lisa [Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN (United States); Department of Pediatrics, University of Tennessee College of Medicine, Memphis, TN (United States); Merchant, Thomas E.; Kun, Larry E. [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN (United States); McCrarey, Lola [Department of Rehabilitation Services, St. Jude Children's Research Hospital, Memphis, TN (United States); and others

2012-01-01

245

Verification of motion induced thread effect during tomotherapy using gel dosimetry  

NASA Astrophysics Data System (ADS)

The purpose of the study was to evaluate how breathing motion during tomotherapy (Accuray, CA, USA) treatment affects the absorbed dose distribution. The experiments were carried out using gel dosimetry and a motion device simulating respiratory-like motion (HexaMotion, ScandiDos, Uppsala, Sweden). Normoxic polyacrylamide gels (nPAG) were irradiated, both during respiratory-like motion and in a static mode. To be able to investigate interplay effects the static absorbed dose distribution was convolved with the motion function and differences between the dynamic and convolved static absorbed dose distributions were interpreted as interplay effects. The expected dose blurring was present and the interplay effects formed a spiral pattern in the lower dose volume. This was expected since the motion induced affects the preset pitch and the theoretically predicted thread effect may emerge. In this study, the motion induced thread effect was experimentally verified for the first time.

Edvardsson, Anneli; Ljusberg, Anna; Ceberg, Crister; Medin, Joakim; Ambolt, Lee; Nordström, Fredrik; Ceberg, Sofie

2015-01-01

246

Compounds of 6Li and natural Li for EPR dosimetry in photon/neutron mixed radiation fields.  

PubMed

Formates and dithionates of 6Li, enriched and 7Li in natural composition of Li offer a possibility to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field for instance at a boron neutron capture therapy (BNCT) facility. Tests with formates and dithionates of enriched 6Li and lithium compounds with natural composition have been performed at the BNCT facility at Studsvik, Sweden. Irradiations have been performed at 3 cm depth in a Perspex phantom in a fluence rate of thermal neutrons 1.8 x 10(9) n cm(-2) s(-1). The compounds were also irradiated in a pure X-ray field from a 4MV linear accelerator at 5 cm depth in a phantom with accurately determined absorbed doses. The signal intensity and shape was investigated within 3 h after the irradiation. A single line spectrum attributed to the CO2- radical was observed after irradiation of lithium formate. An increase in line width occurring after neutron irradiation in comparison with photon irradiation of the 6Li sample was attributed to dipolar broadening between CO2- radicals trapped in the tracks of the alpha particles. A spectrum due to the SO3- radical anion was observed after irradiation of lithium dithionate. The signal amplitude increased using the 6Li in place of the Li with natural composition of isotopes, in studies with low energy X-ray irradiation. Due to the decreased line width, caused by the difference in g(N) and I between the isotopes, the sensitivity with 6Li dithionate may be enhanced by an order of magnitude compared to alanine dosimetry. After comprehensive examination of the different combinations of compounds with different amounts of 6Li and 7Li regarding dosimetry, radiation chemistry and EPR properties these dosimeter material might be used for dose determinations at BNCT treatments and for biomedical experiments. Interesting properties of the radical formation might be visible due to the large difference in ionization density of neutrons compared to photons. PMID:15134730

Lund, E; Gustafsson, H; Danilczuk, M; Sastry, M D; Lund, A

2004-05-01

247

Compounds of 6Li and natural Li for EPR dosimetry in photon/neutron mixed radiation fields  

NASA Astrophysics Data System (ADS)

Formates and dithionates of 6Li, enriched and 7Li in natural composition of Li offer a possibility to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field for instance at a boron neutron capture therapy (BNCT) facility. Tests with formates and dithionates of enriched 6Li and lithium compounds with natural composition have been performed at the BNCT facility at Studsvik, Sweden. Irradiations have been performed at 3 cm depth in a Perspex phantom in a fluence rate of thermal neutrons 1.8×10 9 n cm -2 s -1. The compounds were also irradiated in a pure X-ray field from a 4 MV linear accelerator at 5 cm depth in a phantom with accurately determined absorbed doses. The signal intensity and shape was investigated within 3 h after the irradiation. A single line spectrum attributed to the CO 2- radical was observed after irradiation of lithium formate. An increase in line width occurring after neutron irradiation in comparison with photon irradiation of the 6Li sample was attributed to dipolar broadening between CO 2- radicals trapped in the tracks of the ? particles. A spectrum due to the SO 3- radical anion was observed after irradiation of lithium dithionate. The signal amplitude increased using the 6Li in place of the Li with natural composition of isotopes, in studies with low energy X-ray irradiation. Due to the decreased line width, caused by the difference in gN and I between the isotopes, the sensitivity with 6Li dithionate may be enhanced by an order of magnitude compared to alanine dosimetry. After comprehensive examination of the different combinations of compounds with different amounts of 6Li and 7Li regarding dosimetry, radiation chemistry and EPR properties these dosimeter material might be used for dose determinations at BNCT treatments and for biomedical experiments. Interesting properties of the radical formation might be visible due to the large difference in ionization density of neutrons compared to photons.

Lund, E.; Gustafsson, H.; Danilczuk, M.; Sastry, M. D.; Lund, A.

2004-05-01

248

A new water-equivalent 2D plastic scintillation detectors array for the dosimetry of megavoltage energy photon beams in radiation therapy  

SciTech Connect

Purpose: The objective of this work is to present a new 2D plastic scintillation detectors array (2D-PSDA) designed for the dosimetry of megavoltage (MV) energy photon beams in radiation therapy and to characterize its basic performance. Methods: We developed a 2D detector array consisting of 781 plastic scintillation detectors (PSDs) inserted into a plane of a water-equivalent phantom. The PSDs were distributed on a 26 x 26 cm{sup 2} grid, with an interdetector spacing of 10 mm, except for two perpendicular lines centered on the detection plane, where the spacing was 5 mm. Each PSD was made of a 1 mm diameter by 3 mm long cylindrical polystyrene scintillating fiber coupled to a clear nonscintillating plastic optical fiber. All of the light signals emitted by the PSDs were read simultaneously with an optical system at a rate of one measurement per second. We characterized the performance of the optical system, the angular dependency of the device, and the perturbation of dose distributions caused by the hundreds of PSDs inserted into the phantom. We also evaluated the capacity of the system to monitor complex multileaf collimator (MLC) sequences such as those encountered in step-and-shoot intensity modulated radiation therapy (IMRT) plans. We compared our results with calculations performed by a treatment planning system and with measurements taken with a 2D ionization chamber array and with a radiochromic film. Results: The detector array that we developed allowed us to measure doses with an average precision of better than 1% for cumulated doses equal to or greater than 6.3 cGy. Our results showed that the dose distributions produced by the 6-MV photon beam are not perturbed (within {+-}1.1%) by the presence of the hundreds of PSDs located into the phantom. The results also showed that the variations in the beam incidences have little effect on the dose response of the device. For all incidences tested, the passing rates of the gamma tests between the 2D-PSDA and the treatment planning system were higher than 97.5% when the standard clinical tolerances of 3% or 3 mm were used. Excellent agreement was obtained between the doses measured and calculated when we used the 2D-PSDA for monitoring a MLC sequence from a step-and-shoot IMRT plan. Conclusions: We demonstrated the feasibility of using a large number of PSDs in a new 2D-PSDA for the dosimetry of MV energy photon beams in radiation therapy. The excellent precision, accuracy, and low angular dependence of the device indicate that such a prototype could potentially be used as a high-accuracy quality assurance tool for IMRT and arc therapy patient plan verification. The homogeneity and water-equivalence of the prototype we built suggest that this technology could be extended to multiple detection planes by arranging the fibers into more complex orientations, opening the possibility for 3D dosimetry with PSDs.

Guillot, Mathieu; Beaulieu, Luc; Archambault, Louis; Beddar, Sam; Gingras, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R 2J6 (Canada)

2011-12-15

249

TOPICAL REVIEW: Polymer gel dosimetry  

NASA Astrophysics Data System (ADS)

Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented.

Baldock, C.; De Deene, Y.; Doran, S.; Ibbott, G.; Jirasek, A.; Lepage, M.; McAuley, K. B.; Oldham, M.; Schreiner, L. J.

2010-03-01

250

Topical Review: Polymer gel dosimetry  

PubMed Central

Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. PMID:20150687

Baldock, C; De Deene, Y; Doran, S; Ibbott, G; Jirasek, A; Lepage, M; McAuley, K B; Oldham, M; Schreiner, L J

2010-01-01

251

Medical dosimetry in Hungary  

NASA Astrophysics Data System (ADS)

Radiation exposure of medical staff during cardiological and radiological procedures was investigated. The exposure of medical staff is directly connected to patient exposure. The aim of this study was to determine the distribution of doses on uncovered part of body of medical staff using LiF thermoluminescent (TL) dosimeters in seven locations. Individual Kodak film dosimeters (as authorized dosimetry system) were used for the assessment of medical staff's effective dose. Results achieved on dose distribution measurements confirm that wearing only one film badge under the lead apron does not provide enough information on the personal dose. The value of estimated annual doses on eye lens and extremities (fingers) were in good correlation with international publications.

Turák, O.; Osvay, M.; Ballay, L.

2012-09-01

252

Characterization of a parallel-beam CCD optical-CT apparatus for 3D radiation dosimetry  

Microsoft Academic Search

3D measurement of optical attenuation is of interest in a variety of fields of biomedical importance, including spectrophotometry, optical projection tomography (OPT) and analysis of 3D radiation dosimeters. Accurate, precise and economical 3D measurements of optical density (OD) are a crucial step in enabling 3D radiation dosimeters to enter wider use in clinics. Polymer gels and Fricke gels, as well

Nikola Krstajic; Simon J. Doran

2007-01-01

253

On the validity of 3D polymer gel dosimetry: II. Physico-chemical effects  

NASA Astrophysics Data System (ADS)

This study quantifies some major physico-chemical factors that influence the validity of MRI (PAGAT) polymer gel dosimetry: temperature history (pre-, during and post-irradiation), oxygen exposure (post-irradiation) and volumetric effects (experiment with phantom in which a small test tube is inserted). Present results confirm the effects of thermal history prior to irradiation. By exposing a polymer gel sample to a linear temperature gradient of ˜2.8 °C cm-1 and following the dose deviation as a function of post-irradiation time new insights into temporal variations were added. A clear influence of the temperature treatment on the measured dose distribution is seen during the first hours post-irradiation (resulting in dose deviations up to 12%). This effect diminishes to 5% after 54 h post-irradiation. Imposing a temperature offset (maximum 6 °C for 3 h) during and following irradiation on a series of calibration phantoms results in only a small dose deviation of maximum 4%. Surprisingly, oxygen diffusing in a gel dosimeter up to 48 h post-irradiation was shown to have no effect. Volumetric effects were studied by comparing the dose distribution in a homogeneous phantom compared to the dose distribution in a phantom in which a small test tube was inserted. This study showed that the dose measured inside the test tube was closer to the ion chamber measurement in comparison to the reference phantom without test tube by almost 7%. It is demonstrated that physico-chemical effects are not the major causes for the dose discrepancies encountered in the reproducibility study discussed in the concurrent paper (Vandecasteele and De Deene 2013a Phys. Med. Biol. 58 19-42). However, it is concluded that these physico-chemical effects are important factors that should be addressed to further improve the dosimetric accuracy of 3D MRI polymer gel dosimetry. Both authors contributed equally to this study.

Vandecasteele, Jan; De Deene, Yves

2013-01-01

254

On the validity of 3D polymer gel dosimetry: II. physico-chemical effects.  

PubMed

This study quantifies some major physico-chemical factors that influence the validity of MRI (PAGAT) polymer gel dosimetry: temperature history (pre-, during and post-irradiation), oxygen exposure (post-irradiation) and volumetric effects (experiment with phantom in which a small test tube is inserted). Present results confirm the effects of thermal history prior to irradiation. By exposing a polymer gel sample to a linear temperature gradient of ?2.8 °C cm?¹ and following the dose deviation as a function of post-irradiation time new insights into temporal variations were added. A clear influence of the temperature treatment on the measured dose distribution is seen during the first hours post-irradiation (resulting in dose deviations up to 12%). This effect diminishes to 5% after 54 h post-irradiation. Imposing a temperature offset (maximum 6 °C for 3 h) during and following irradiation on a series of calibration phantoms results in only a small dose deviation of maximum 4%. Surprisingly, oxygen diffusing in a gel dosimeter up to 48 h post-irradiation was shown to have no effect. Volumetric effects were studied by comparing the dose distribution in a homogeneous phantom compared to the dose distribution in a phantom in which a small test tube was inserted. This study showed that the dose measured inside the test tube was closer to the ion chamber measurement in comparison to the reference phantom without test tube by almost 7%. It is demonstrated that physico-chemical effects are not the major causes for the dose discrepancies encountered in the reproducibility study discussed in the concurrent paper (Vandecasteele and De Deene 2013a Phys. Med. Biol. 58 19-42). However, it is concluded that these physico-chemical effects are important factors that should be addressed to further improve the dosimetric accuracy of 3D MRI polymer gel dosimetry. PMID:23221322

Vandecasteele, Jan; De Deene, Yves

2013-01-01

255

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program (HEDP) which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee (HPDAC) which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document.

Rathbone, Bruce A.

2009-08-28

256

Considerations regarding the implementation of EPR dosimetry for the population in the vicinity of Semipalatinsk nuclear test site based on experience from other radiation accidents.  

PubMed

General aspects of applying the method of retrospective dose estimation by electron paramagnetic resonance spectroscopy of human tooth enamel (EPR dosimetry) to the population residing in the vicinity of the Semipalatinsk nuclear test site are analyzed and summarized. The analysis is based on the results obtained during 20 years of investigations conducted in the Medical Radiological Research Center regarding the development and practical application of this method for wide-scale dosimetrical investigation of populations exposed to radiation after the Chernobyl accident and other radiation accidents. PMID:16571946

Skvortsov, Valeriy; Ivannikov, Alexander; Tikunov, Dimitri; Stepanenko, Valeriy; Borysheva, Natalie; Orlenko, Sergey; Nalapko, Mikhail; Hoshi, Masaharu

2006-02-01

257

Practical dosimetry methods for the determination of effective skin and breast dose for a modern CT system, incorporating partial irradiation and prospective cardiac gating  

PubMed Central

Objective For CT coronary angiography (CTCA), a generic chest conversion factor returns a significant underestimate of effective dose. The aim of this manuscript is to communicate new dosimetry methods to calculate weighted CT dose index (CTDIw), effective dose, entrance surface dose (ESD) and organ dose to the breast for prospectively gated CTCA. Methods CTDIw in 32 cm diameter Perspex phantom was measured using an adapted technique, accounting for the segmented scan characteristic. Gafchromic XRCT film (International Speciality Products, New Jersey, NJ) was used to measure the distribution and magnitude of ESD. Breast dose was measured using high sensitivity metal oxide semiconductor field-effect transistors and compared to the computer based imaging performance assessment of CT scanners (ImPACT) dosimetry calculations. Results For a typical cardiac scan the mean ESD remained broadly constant (7–9 mGy) when averaged over the circumference of the Perspex phantom. Typical absorbed dose to the breast with prospectively gated protocols was within the range 2–15 mGy. The subsequent lifetime attributable risk (LAR) of cancer incidence to the breast was found at 0.01–0.06 for a 20-year-old female. This compares favourably to 100 mGy (LAR ?0.43) for a retrospectively gated CTCA. Conclusions Care must be taken when considering radiation dosimetry associated with prospectively gated scanning for CTCA and a method has been conveyed to account for this. Breast doses for prospectively gated CTCA are an order of magnitude lower than retrospectively gated scans. Optimisation of cardiac protocols is expected to show further dose reduction. PMID:21896660

Loader, R J; Gosling, O; Roobottom, C; Morgan-Hughes, G; Rowles, N

2012-01-01

258

Study and development of an innovative electron beam imaging system for dosimetry in IORT (Intra Operative Radiation Therapy)  

NASA Astrophysics Data System (ADS)

Intra Operative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionising radiation to the cancer tissue, after tumour ablation, during surgery, while reducing the exposure of normal surrounding tissue. The Novac7 is a new linear accelerator expressly conceived to perform in the operating theatre. This accelerator supplies electron beams with high dose rate (up to 20 cGy/min). Because of these peculiar characteristics, classical dosimetric techniques are not able to give at once a real-time response and an extensive measure of the absorbed dose. In the framework of a research contract between ENEA (Italian National Agency for Environment and Alternative Energy Research) and the Physics Department of the University of Bologna, Italy, a new system has been developed to study and visualise the Novac7 electron beam. The system is conceived as a grid that consists of two bundles of scintillating optical fibers (SOF) over-crossing each other, optically coupled with two arrays of photodiodes as read-out system. The instrument samples the delivered beam at 100 Hz. A dedicated software collects the signals from the photodiodes and reconstructs the bi-dimensional image. Moreover it provides a series of dosimetric parameters. We studied an appropriate reconstruction algorithm searching for the best compromise between computational complexity and high precision. An accelerator ranging from 3 to 12 MeV has been used for the experimental tests. The various phases of design, development and characterisation of the instrument will be illustrated, as well as some experimental tests performed with the prototype. The system is able to give a real time response (within 30 s), while the resolution is of 1 mm. The response is linear versus dose and the measures are not affected by the high dose rate. The conclusions confirm the capability of the instrument to overcome problems encountered with classic dosimetry, showing that the results obtained strongly encourage the continuation of this research.

Brancaccio, Rosa; Bettuzzi, Matteo; Casali, Franco; Cornacchia, Samantha; Morigi, Maria Pia; Pasini, Alessandro; Ronsivalle, C.; Tata, A.

2006-06-01

259

Dosimetry in diagnostic radiology  

Microsoft Academic Search

Dosimetry is an area of increasing importance in diagnostic radiology. There is a realisation amongst health professionals that the radiation dose received by patients from modern X-ray examinations and procedures can be at a level of significance for the induction of cancer across a population, and in some unfortunate instances, in the acute damage to particular body organs such as

Ahmed Meghzifene; David R. Dance; Donald McLean; Hans-Michael Kramer

2010-01-01

260

Numerical assessment of radiation binary targeted therapy for HER-2 positive breast cancers: advanced calculations and radiation dosimetry.  

PubMed

In our previous publication (Mundy et al 2006 Phys. Med. Biol. 51 1377) we have described the theoretical assessment of our novel approach in radiation binary targeted therapy for HER-2 positive breast cancers and summarized the future directions in this area of research. In this paper we advanced the numerical analysis to show the detailed radiation dose distribution for various neutron sources in combination with the required boron concentration and allowed radiation skin doses. We once again proved the feasibility of the concept and will use these data and conclusions to start with the experimental verifications. PMID:17664606

Sztejnberg Gonçalves-Carralves, Manuel L; Jevremovic, Tatjana

2007-07-21

261

Proton Radiotherapy for Pediatric Bladder/Prostate Rhabdomyosarcoma: Clinical Outcomes and Dosimetry Compared to Intensity-Modulated Radiation Therapy  

SciTech Connect

Purpose: In this study, we report the clinical outcomes of 7 children with bladder/prostate rhabdomyosarcoma (RMS) treated with proton radiation and compare proton treatment plans with matched intensity-modulated radiation therapy (IMRT) plans, with an emphasis on dose savings to reproductive and skeletal structures. Methods and Materials: Follow-up consisted of scheduled clinic appointments at our institution or direct communication with the treating physicians for referred patients. Each proton radiotherapy plan used for treatment was directly compared to an IMRT plan generated for the study. Clinical target volumes and normal tissue volumes were held constant to facilitate dosimetric comparisons. Each plan was optimized for target coverage and normal tissue sparing. Results: Seven male patients were treated with proton radiotherapy for bladder/prostate RMS at the Massachusetts General Hospital between 2002 and 2008. Median age at treatment was 30 months (11-70 months). Median follow-up was 27 months (10-90 months). Four patients underwent a gross total resection prior to radiation, and all patients received concurrent chemotherapy. Radiation doses ranged from 36 cobalt Gray equivalent (CGE) to 50.4 CGE. Five of 7 patients were without evidence of disease and with intact bladders at study completion. Target volume dosimetry was equivalent between the two modalities for all 7 patients. Proton radiotherapy led to a significant decrease in mean organ dose to the bladder (25.1 CGE vs. 33.2 Gy; p = 0.03), testes (0.0 CGE vs. 0.6 Gy; p = 0.016), femoral heads (1.6 CGE vs. 10.6 Gy; p = 0.016), growth plates (21.7 CGE vs. 32.4 Gy; p = 0.016), and pelvic bones (8.8 CGE vs. 13.5 Gy; p = 0.016) compared to IMRT. Conclusions: This study provides evidence of significant dose savings to normal structures with proton radiotherapy compared to IMRT and is well tolerated in this patient population. The long-term impact of these reduced doses can be tested in future studies incorporating extended follow-up, objective outcome measures, and quality-of-life analyses.

Cotter, Shane E. [Harvard Radiation Oncology Program, Boston, Massachusetts (United States); Herrup, David A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Friedmann, Alison [Department of Pediatric Hematology-Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Macdonald, Shannon M. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Pieretti, Raphael V. [Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts (United States); Robinson, Gregoire; Adams, Judith; Tarbell, Nancy J. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Yock, Torunn I., E-mail: tyock@partners.org [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States)

2011-12-01

262

Effect of different breathing patterns in the same patient on stereotactic ablative body radiotherapy dosimetry for primary renal cell carcinoma: A case study  

SciTech Connect

Stereotactic ablative body radiotherapy (SABR) for primary renal cell carcinoma (RCC) targets requires motion management strategies to verify dose delivery. This case study highlights the effect of a change in patient breathing amplitude on the dosimetry to organs at risk and target structures. A 73-year-old male patient was planned for receiving 26 Gy of radiation in 1 fraction of SABR for a left primary RCC. The patient was simulated with four-dimensional computed tomography (4DCT) and the tumor internal target volume (ITV) was delineated using the 4DCT maximum intensity projection. However, the initially planned treatment was abandoned at the radiation oncologist's discretion after pretreatment cone-beam CT (CBCT) motion verification identified a greater than 50% reduction in superior to inferior diaphragm motion as compared with the planning 4DCT. This patient was resimulated with respiratory coaching instructions. To assess the effect of the change in breathing on the dosimetry to the target, each plan was recalculated on the data set representing the change in breathing condition. A change from smaller to larger breathing showed a 46% loss in planning target volume (PTV) coverage, whereas a change from larger breathing to smaller breathing resulted in an 8% decrease in PTV coverage. ITV coverage was similarly reduced by 8% in both scenarios. This case study highlights the importance of tools to verify breathing motion prior to treatment delivery. 4D image guided radiation therapy verification strategies should focus on not only verifying ITV margin coverage but also the effect on the surrounding organs at risk.

Pham, Daniel, E-mail: Daniel.Pham@petermac.org [Radiotherapy Services, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Kron, Tomas [Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Foroudi, Farshad; Siva, Shankar [Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)

2013-10-01

263

On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry  

NASA Astrophysics Data System (ADS)

A systematic analysis of the available data has been carried out for mass energy-absorption coefficients and their ratios for air, graphite and water for photon energies between 1 keV and 2 MeV, using representative kilovoltage x-ray spectra for mammography and diagnostic radiology below 100 kV, and for 192Ir and 60Co gamma-ray spectra. The aim of this work was to establish ‘an envelope of uncertainty’ based on the spread of the available data. Type A uncertainties were determined from the results of Monte Carlo (MC) calculations with the PENELOPE and EGSnrc systems, yielding mean values for µen/? with a given statistical standard uncertainty. Type B estimates were based on two groupings. The first grouping consisted of MC calculations based on a similar implementation but using different data and/or approximations. The second grouping was formed by various datasets, obtained by different authors or methods using the same or different basic data, and with different implementations (analytical, MC-based, or a combination of the two); these datasets were the compilations of NIST, Hubbell, Johns-Cunningham, Attix and Higgins, plus MC calculations with PENELOPE and EGSnrc. The combined standard uncertainty, uc, for the µen/? values for the mammography x-ray spectra is 2.5%, decreasing gradually to 1.6% for kilovoltage x-ray spectra up to 100 kV. For 60Co and 192Ir, uc is approximately 0.1%. The Type B uncertainty analysis for the ratios of µen/? values includes four methods of analysis and concludes that for the present data the assumption that the data interval represents 95% confidence limits is a good compromise. For the mammography x-ray spectra, the combined standard uncertainties of (µen/?)graphite,air and (µen/?)graphite,water are 1.5%, and 0.5% for (µen/?)water,air, decreasing gradually down to uc = 0.1% for the three µen/? ratios for the gamma-ray spectra. The present estimates are shown to coincide well with those of Hubbell (1977 Rad. Res. 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (µen/?)graphite,air for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication).

Andreo, Pedro; Burns, David T.; Salvat, Francesc

2012-04-01

264

On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry.  

PubMed

A systematic analysis of the available data has been carried out for mass energy-absorption coefficients and their ratios for air, graphite and water for photon energies between 1 keV and 2 MeV, using representative kilovoltage x-ray spectra for mammography and diagnostic radiology below 100 kV, and for ¹?²Ir and ??Co gamma-ray spectra. The aim of this work was to establish 'an envelope of uncertainty' based on the spread of the available data. Type A uncertainties were determined from the results of Monte Carlo (MC) calculations with the PENELOPE and EGSnrc systems, yielding mean values for µ(en)/? with a given statistical standard uncertainty. Type B estimates were based on two groupings. The first grouping consisted of MC calculations based on a similar implementation but using different data and/or approximations. The second grouping was formed by various datasets, obtained by different authors or methods using the same or different basic data, and with different implementations (analytical, MC-based, or a combination of the two); these datasets were the compilations of NIST, Hubbell, Johns-Cunningham, Attix and Higgins, plus MC calculations with PENELOPE and EGSnrc. The combined standard uncertainty, u(c), for the µ(en)/? values for the mammography x-ray spectra is 2.5%, decreasing gradually to 1.6% for kilovoltage x-ray spectra up to 100 kV. For ??Co and ¹?²Ir, u(c) is approximately 0.1%. The Type B uncertainty analysis for the ratios of µ(en)/? values includes four methods of analysis and concludes that for the present data the assumption that the data interval represents 95% confidence limits is a good compromise. For the mammography x-ray spectra, the combined standard uncertainties of (µ(en)/?)(graphite,air) and (µ(en)/?)(graphite,water) are 1.5%, and 0.5% for (µ(en)/?)(water,air), decreasing gradually down to u(c) = 0.1% for the three µ(en)/? ratios for the gamma-ray spectra. The present estimates are shown to coincide well with those of Hubbell (1977 Rad. Res. 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (µ(en)/?)(graphite,air) for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication). PMID:22451262

Andreo, Pedro; Burns, David T; Salvat, Francesc

2012-04-21

265

MODIFICATION OF SHIRT BUTTONS FOR RETROSPECTIVE RADIATION DOSIMETRY AFTER A RADIOLOGICAL EVENT  

E-print Network

are presented for a personal radiation dosimeter in the form of a clothing button to provide gamma-ray dose subsequently exposed to doses of 137 Cs gamma rays ranging from 0.75 to 8.2 Gy. The rods were removed from exposure would depend on many parameters, such as proximity, length of expo- sure, and shielding

Brenner, David Jonathan

266

Investigation of scintillator and fibre light in plastic scintillation dosimetry  

Microsoft Academic Search

Plastic scintillation dosimetry is a new and promising method of measuring dose in a radiation therapy beam. In this dosimetry system, the light signal produced in a miniature scintillator is transmitted to a photomultiplier tube via fiber optic cables. This system offers many advantages over conventional dosimetry methods, but an undesired radiation induced light signal is produced in the optical

Steven Francis Deboer

1993-01-01

267

Characterisation of the thermoluminescence (TL) properties of tailor-made Ge-doped silica glass fibre for applications in medical radiation therapy dosimetry  

NASA Astrophysics Data System (ADS)

We have investigated the characterisation of new fabricated material Ge doped silica glass thermoluminescence TL dosimeter (Photonic Research Centre, University of Malaya) for medical radiation dosimetry at therapy energy. Previously, the dosimeter has been studied to provide ideal dosimetry system, suitable to ensure an accurate delivery of radiation doses to tumour tissue while minimising the amount of radiation administrated to healthy tissue. Both energies of photon and electron were used in this experiment for a dose range of 1 to 5 Gy. The various sizes of core diameter Ge doped silica glass (120, 241, 362, 483 and 604 ?m) were exposed by using linear accelerator at Pantai Medical Centre. For both energies, the optical fibres were found to produce a flat response to a fixed photon and electron doses to within 4% (S.D) of the mean of the TL distribution. In terms of dose response, the fibres provide linear response over the range investigated, from a fraction of 1-5 Gy. The finding shows 120 ?m fibres have 1.82 greater dose response than 604 pm fibres irradiated at 6 MV photon with a fixed dose of 3 Gy. While for electron energy 12 MeV, the response shows 120 ?m fibres have 1.58 greater dose response compared to 604 ?m fibres. The good responses are suitable to make these tailor-made doped silica fibres a promising TL material for use as a dosimetric system in medical radiation therapy.

Zahaimi, N. A.; Zin, H.; Mahdiraji, G. A.; Rahman, A. L. Abdul; Bradley, D. A.; Rahman, A. T. Abdul

2014-11-01

268

1986 Annual Conference on Nuclear and Space Radiation Effects, 23rd, Providence, RI, July 21-23, 1986, Proceedings  

NASA Technical Reports Server (NTRS)

The present conference on the effects of nuclear and space radiation on electronic hardware gives attention to topics in the basic mechanisms of radiation effects, dosimetry and energy-dependent effects, electronic device radiation hardness assurance, SOI/SOS radiation effects, spacecraft charging and space radiation, IC radiation effects and hardening, single-event upset (SEU) phenomena and hardening, and EMP/SGEMP/IEMP phenomena. Specific treatments encompass the generation of interface states by ionizing radiation in very thin MOS oxides, the microdosimetry of meson energy deposited on 1-micron sites in Si, total dose radiation and engineering studies, plasma interactions with biased concentrator solar cells, the transient imprint memory effect in MOS memories, mechanisms leading to SEU, and the vaporization and breakdown of thin columns of water.

Ellis, Thomas D. (editor)

1986-01-01

269

Uranium Dispersion and Dosimetry (UDAD) Code  

Microsoft Academic Search

The Uranium Dispersion and Dosimetry (UDAD) Code provides estimates of potential radiation exposure to individuals and to the general population in the vicinity of a uranium processing facility. The UDAD Code incorporates the radiation dose from the airborne release of radioactive materials, and includes dosimetry of inhalation, ingestion, and external exposures. The removal of raioactive particles from a contaminated area

M. H. Momeni; Y. Yuan; A. J. Zielen

1979-01-01

270

Improved Radiation Dosimetry/Risk Estimates to Facilitate Environmental Management of Plutonium-Contaminated Sites  

SciTech Connect

This report summarizes 4 years of research achievements in this Office of Science (BER), U.S. Department of Energy (DOE) project. The research described was conducted by scientists and supporting staff at Lovelace Respiratory Research Institute (LRRI)/Lovelace Biomedical and Environmental Research Institute (LBERI) and the Southern Urals Biophysics Institute (SUBI). All project objectives and goals were achieved. A major focus was on obtaining improved cancer risk estimates for exposure via inhalation to plutonium (Pu) isotopes in the workplace (DOE radiation workers) and environment (public exposures to Pu-contaminated soil). A major finding was that low doses and dose rates of gamma rays can significantly suppress cancer induction by alpha radiation from inhaled Pu isotopes. The suppression relates to stimulation of the body's natural defenses, including immunity against cancer cells and selective apoptosis which removes precancerous and other aberrant cells.

Scott, Bobby R.; Tokarskaya, Zoya B.; Zhuntova, Galina V.; Osovets, Sergey V.; Syrchikov, Victor A., Belyaeva, Zinaida D.

2007-12-14

271

Nanosensor dosimetry of mouse blood proteins after exposure to ionizing radiation  

NASA Astrophysics Data System (ADS)

Giant magnetoresistive (GMR) nanosensors provide a novel approach for measuring protein concentrations in blood for medical diagnosis. Using an in vivo mouse radiation model, we developed protocols for measuring Flt3 ligand (Flt3lg) and serum amyloid A1 (Saa1) in small amounts of blood collected during the first week after X-ray exposures of sham, 0.1, 1, 2, 3, or 6 Gy. Flt3lg concentrations showed excellent dose discrimination at >= 1 Gy in the time window of 1 to 7 days after exposure except 1 Gy at day 7. Saa1 dose response was limited to the first two days after exposure. A multiplex assay with both proteins showed improved dose classification accuracy. Our magneto-nanosensor assay demonstrates the dose and time responses, low-dose sensitivity, small volume requirements, and rapid speed that have important advantages in radiation triage biodosimetry.

Kim, Dokyoon; Marchetti, Francesco; Chen, Zuxiong; Zaric, Sasa; Wilson, Robert J.; Hall, Drew A.; Gaster, Richard S.; Lee, Jung-Rok; Wang, Junyi; Osterfeld, Sebastian J.; Yu, Heng; White, Robert M.; Blakely, William F.; Peterson, Leif E.; Bhatnagar, Sandhya; Mannion, Brandon; Tseng, Serena; Roth, Kristen; Coleman, Matthew; Snijders, Antoine M.; Wyrobek, Andrew J.; Wang, Shan X.

2013-07-01

272

The small-animal radiation research platform (SARRP): dosimetry of a focused lens system  

Microsoft Academic Search

A small animal radiation platform equipped with on-board cone-beam CT and conformal irradiation capabilities is being constructed for translational research. To achieve highly localized dose delivery, an x-ray lens is used to focus the broad beam from a 225 kVp x-ray tube down to a beam with a full width half maximum (FWHM) of approximately 1.5 mm in the energy

Hua Deng; Christopher W. Kennedy; Elwood Armour; Erik Tryggestad; Eric Ford; Todd McNutt; Licai Jiang; John Wong

2007-01-01

273

Aircrew dosimetry using the predictive code for aircrew radiation exposure (PCAIRE)  

Microsoft Academic Search

During 2003, a portable instrument suite was used to conduct cosmic radiation measurements on 49 jet-altitude flights, which brings the total number of in-flight measurements by this research group to over 160 flights since 1999. From previous measurements, correlations have been developed to allow for the interpolation of the dose-equivalent rate for any global position, altitude and date. The result

B. J. Lewis; L. G. I. Bennett; A. R. Green; A. Butler; M. Desormeaux; F. Kitching; M. J. McCall; B. Ellaschuk; M. Pierre

2005-01-01

274

The UF Family of hybrid phantoms of the pregnant female for computational radiation dosimetry  

NASA Astrophysics Data System (ADS)

Efforts to assess in utero radiation doses and related quantities to the developing fetus should account for the presence of the surrounding maternal tissues. Maternal tissues can provide varying levels of protection to the fetus by shielding externally-emitted radiation or, alternatively, can become sources of internally-emitted radiation following the biokinetic uptake of medically-administered radiopharmaceuticals or radionuclides located in the surrounding environment—as in the case of the European Union’s SOLO project (Epidemiological Studies of Exposed Southern Urals Populations). The University of Florida had previously addressed limitations in available computational phantom representation of the developing fetus by constructing a series of hybrid computational fetal phantoms at eight different ages and three weight percentiles. Using CT image sets of pregnant patients contoured using 3D-DOCTORTM, the eight 50th percentile fetal phantoms from that study were systematically combined in RhinocerosTM with the UF adult non-pregnant female to yield a series of reference pregnant female phantoms at fetal ages 8, 10, 15, 20, 25, 30, 35 and 38?weeks post-conception. Deformable, non-uniform rational B-spline surfaces were utilized to alter contoured maternal anatomy in order to (1) accurately position and orient each fetus and surrounding maternal tissues and (2) match target masses of maternal soft tissue organs to reference data reported in the literature.

Maynard, Matthew R.; Long, Nelia S.; Moawad, Nash S.; Shifrin, Roger Y.; Geyer, Amy M.; Fong, Grant; Bolch, Wesley E.

2014-08-01

275

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Nuclear accident dosimetry. 835.1304 ...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations...individuals to radiation from a nuclear accident is possible, shall...

2012-01-01

276

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Nuclear accident dosimetry. 835.1304 ...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations...individuals to radiation from a nuclear accident is possible, shall...

2010-01-01

277

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 2014-01-01 false Nuclear accident dosimetry. 835.1304 ...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations...individuals to radiation from a nuclear accident is possible, shall...

2014-01-01

278

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Nuclear accident dosimetry. 835.1304 ...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations...individuals to radiation from a nuclear accident is possible, shall...

2011-01-01

279

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Nuclear accident dosimetry. 835.1304 ...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations...individuals to radiation from a nuclear accident is possible, shall...

2013-01-01

280

Cataractogenic effects of proton radiation  

E-print Network

CATARACTOGENIC EFFECTS OF PROTON RADIATION A Thesis by James Ronald Kyzar Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1972 Major Subject...: Veterinary Physiology CATARACTOGENIC EFFECTS OF PROTON RADIATION A Thesis by James Ronald Kyzar Approved as to style and content by: (Char of Committee) (Head of Depar ent) (Membei / (Member (Member ) May 1972 ABSTRACT Cataractogenic Effects...

Kyzar, James Ronald

1972-01-01

281

BIOLOGICAL EFFECTS OF RADIOFREQUENCY RADIATION  

EPA Science Inventory

The document presents a critical review of the available literature on the biological effects of radiofrequency (RF) radiation. The objective was to summarize and evaluate the existing database for use in developing RF-radiation exposure guidance for the general public. The frequ...

282

Dosimetry in brain tumor phantom at 15 MV 3D conformal radiation therapy  

PubMed Central

Glioblastoma multiforme (GBM) is the most common, aggressive, highly malignant and infiltrative of all brain tumors with low rate of control. The main goal of this work was to evaluate the spatial dose distribution into a GBM simulator inside a head phantom exposed to a 15 MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Such phantom holds the following synthetic structures: brain and spinal cord, skull, cervical and thoracic vertebrae, jaw, hyoid bone, laryngeal cartilages, head and neck muscles and skin. Computer tomography (CT) of the simulator was taken, capturing a set of contrasted references. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples at coronal, sagittal-anterior and sagittal-posterior positions, inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, measured at coronal section, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. And, as final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. PMID:23829593

2013-01-01

283

Dosimetry in brain tumor phantom at 15 MV 3D conformal radiation therapy.  

PubMed

Glioblastoma multiforme (GBM) is the most common, aggressive, highly malignant and infiltrative of all brain tumors with low rate of control. The main goal of this work was to evaluate the spatial dose distribution into a GBM simulator inside a head phantom exposed to a 15 MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Such phantom holds the following synthetic structures: brain and spinal cord, skull, cervical and thoracic vertebrae, jaw, hyoid bone, laryngeal cartilages, head and neck muscles and skin. Computer tomography (CT) of the simulator was taken, capturing a set of contrasted references. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples at coronal, sagittal-anterior and sagittal-posterior positions, inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, measured at coronal section, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. And, as final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. PMID:23829593

Thompson, Larissa; Dias, Humberto Galvão; Campos, Tarcísio Passos Ribeiro

2013-01-01

284

Dosimetry of secondary cosmic radiation up to an altitude of 30 km.  

PubMed

Dosimetric measurements in the field of secondary cosmic radiation were extensively made during the last years. Since the majority of these measurements were performed on-board passenger aircraft at altitudes between 10 and 12 km, measurements at higher altitudes are desirable for the verification of the legal dose assessment procedures for aircrew. A simple solution is to use a high-altitude balloon that reaches altitudes as high as 30 km. In this work, it is shown that the dose rate profile up to 30 km can be measured with acceptable uncertainties using a Si-detector. PMID:24345463

Wissmann, F; Burda, O; Khurana, S; Klages, T; Langner, F

2014-10-01

285

Effect of brachytherapy technique and patient characteristics on cervical cancer implant dosimetry.  

PubMed

Our purpose was to evaluate the relationship between brachytherapy technique and patient characteristics on dose to organs-at-risk (OARs) in patients undergoing high dose rate (HDR) brachytherapy for cervical cancer. From 1998 to 2008, 31 patients with cervical cancer with full dosimetric data were identified who received definitive external-beam radiation and HDR brachytherapy with tandem and ovoid applicators. Doses were recorded at point A, the International Commission on Radiation Units and Measurements (ICRU)-38 rectal point, the ICRU-38 bladder point, the vaginal surface, and the pelvic sidewall. Generalized estimating equations were used to determine the significance of changes in OAR to point A dose ratios with differences in brachytherapy technique or patient characteristics. Patients underwent a median of 5 brachytherapy procedures (range, 3 to 5), with a total of 179 procedures for 31 patients. For all brachytherapy treatments, the average ratios between the doses for the rectal, bladder, vaginal surface, and pelvic sidewall reference points to those at point A were 0.49, 0.59, 1.15, and 0.17, respectively. In general, decreased OAR dose was associated with a lower stage, younger age, increased ovoid size, increased tandem length, and earlier implant number. Increased tandem curvature significantly increased bladder dose and decreased rectal dose. Intravenous anesthesia usage was not correlated with improved dosimetry. This study allowed identification of patient and procedure characteristics influencing OAR dosing. Although the advent of 3-dimensional (3D) image-guided brachytherapy will bring new advances in treatment optimization, the actual technique involved at the time of the brachytherapy implant procedure will remain important. PMID:23973016

Anker, Christopher J; O'Donnell, Kristen; Boucher, Kenneth M; Gaffney, David K

2013-01-01

286

Effect of brachytherapy technique and patient characteristics on cervical cancer implant dosimetry  

SciTech Connect

Our purpose was to evaluate the relationship between brachytherapy technique and patient characteristics on dose to organs-at-risk (OARs) in patients undergoing high dose rate (HDR) brachytherapy for cervical cancer. From 1998 to 2008, 31 patients with cervical cancer with full dosimetric data were identified who received definitive external-beam radiation and HDR brachytherapy with tandem and ovoid applicators. Doses were recorded at point A, the International Commission on Radiation Units and Measurements (ICRU)-38 rectal point, the ICRU-38 bladder point, the vaginal surface, and the pelvic sidewall. Generalized estimating equations were used to determine the significance of changes in OAR to point A dose ratios with differences in brachytherapy technique or patient characteristics. Patients underwent a median of 5 brachytherapy procedures (range, 3 to 5), with a total of 179 procedures for 31 patients. For all brachytherapy treatments, the average ratios between the doses for the rectal, bladder, vaginal surface, and pelvic sidewall reference points to those at point A were 0.49, 0.59, 1.15, and 0.17, respectively. In general, decreased OAR dose was associated with a lower stage, younger age, increased ovoid size, increased tandem length, and earlier implant number. Increased tandem curvature significantly increased bladder dose and decreased rectal dose. Intravenous anesthesia usage was not correlated with improved dosimetry. This study allowed identification of patient and procedure characteristics influencing OAR dosing. Although the advent of 3-dimensional (3D) image-guided brachytherapy will bring new advances in treatment optimization, the actual technique involved at the time of the brachytherapy implant procedure will remain important.

Anker, Christopher J., E-mail: chris.anker@hci.utah.edu [Department of Radiation Oncology, Huntsman Cancer Hospital, University of Utah, Salt Lake City, UT (United States); O'Donnell, Kristen [Department of Radiation Oncology, The University of Arizona, Tucson, AZ (United States); Boucher, Kenneth M. [Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT (United States); Gaffney, David K. [Department of Radiation Oncology, Huntsman Cancer Hospital, University of Utah, Salt Lake City, UT (United States)

2013-01-01

287

Radiation Therapy Side Effects Sheets  

Cancer.gov

Radiation therapy fact sheets that help patients understand their treatment and manage side effects. The fact sheets (also available in audio) have tips from patients and healthcare providers, and questions to ask providers.

288

Radiation effects on bacterial cells  

NASA Technical Reports Server (NTRS)

Study reveals the physicochemical and biochemical mechanisms which alter or modify the effects of high-energy radiation on living cells. An in-depth discussion is presented emphasizing the importance of optimizing bacterial treatment with glycerol.

Powers, E. L.

1968-01-01

289

Health Effects of UV Radiation  

MedlinePLUS

Fact Sheet Download the Health Effects of Overexposure to the Sun (PDF) Ozone layer depletion decreases our atmosphere’s natural protection from the sun’s harmful ultraviolet (UV) radiation. This Web page provides an overview of ...

290

Pediatric radiation dosimetry for positron-emitting radionuclides using anthropomorphic phantoms  

SciTech Connect

Purpose: Positron emission tomography (PET) plays an important role in the diagnosis, staging, treatment, and surveillance of clinically localized diseases. Combined PET/CT imaging exhibits significantly higher sensitivity, specificity, and accuracy than conventional imaging when it comes to detecting malignant tumors in children. However, the radiation dose from positron-emitting radionuclide to the pediatric population is a matter of concern since children are at a particularly high risk when exposed to ionizing radiation.Methods: The authors evaluate the absorbed fractions and specific absorbed fractions (SAFs) of monoenergy photons/electrons as well as S-values of 9 positron-emitting radionuclides (C-11, N-13, O-15, F-18, Cu-64, Ga-68, Rb-82, Y-86, and I-124) in 48 source regions for 10 anthropomorphic pediatric hybrid models, including the reference newborn, 1-, 5-, 10-, and 15-yr-old male and female models, using the Monte Carlo N-Particle eXtended general purpose Monte Carlo transport code.Results: The self-absorbed SAFs and S-values for most organs were inversely related to the age and body weight, whereas the cross-dose terms presented less correlation with body weight. For most source/target organ pairs, Rb-82 and Y-86 produce the highest self-absorbed and cross-absorbed S-values, respectively, while Cu-64 produces the lowest S-values because of the low-energy and high-frequency of electron emissions. Most of the total self-absorbed S-values are contributed from nonpenetrating particles (electrons and positrons), which have a linear relationship with body weight. The dependence of self-absorbed S-values of the two annihilation photons varies to the reciprocal of 0.76 power of the mass, whereas the self-absorbed S-values of positrons vary according to the reciprocal mass.Conclusions: The produced S-values for common positron-emitting radionuclides can be exploited for the assessment of radiation dose delivered to the pediatric population from various PET radiotracers used in clinical and research settings. The mass scaling method for positron-emitters can be used to derive patient-specific S-values from data of reference phantoms.

Xie, Tianwu [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva 4 (Switzerland)] [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva 4 (Switzerland); Bolch, Wesley E. [Departments of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States)] [Departments of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States); Lee, Choonsik [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Rockville, Maryland 20850 (United States)] [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Rockville, Maryland 20850 (United States); Zaidi, Habib [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva 4 (Switzerland) [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva 4 (Switzerland); Geneva Neuroscience Center, Geneva University, CH-1205 Geneva (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, 9700 RB Groningen (Netherlands)

2013-10-15

291

New developments in radiochromic film dosimetry.  

PubMed

NIST has been a pioneer in the use of radiochromic film for medical dosimetry applications. Beginning in 1988 with experiments with (90)Sr/Y ophthalmic applicators, this work has continued into the present. A review of the latest applications is presented, which include high activity low-energy photon source dosimetry and ultra-high resolution film densitometry for dose enhancement near stents and microbeam radiation therapy dosimetry. An exciting recent development is the availability of a new radiochromic emulsion which has been developed for IMRT dosimetry. This emulsion is an order of magnitude more sensitive than was previously available. Measurements of the sensitivity and uniformity of samples of this new film are reported, using a spectrophotometer and two scanning laser densitometers. A unique feature of the new emulsion is that the peak of the absorbance spectrum falls at the wavelength of the HeNe lasers used in the densitometer, maximising sensitivity. When read at a wavelength of 633 nm, sensitivities on the order of 900 mAU Gy(-1) were determined for this new film type, compared with about 40 mAU Gy(-1) for type HS film, 20 mAU Gy(-1) for type MD-55-2 film, and 3 mAU Gy(-1) for type HD-810. Film uniformities were found to be good, on the order of 6% peak to peak. However, there is a strong polarisation effect in the samples examined, requiring care in film orientation during readout. PMID:16987914

Soares, C G

2006-01-01

292

Internal dosimetry technical basis manual  

SciTech Connect

The internal dosimetry program at the Savannah River Site (SRS) consists of radiation protection programs and activities used to detect and evaluate intakes of radioactive material by radiation workers. Examples of such programs are: air monitoring; surface contamination monitoring; personal contamination surveys; radiobioassay; and dose assessment. The objectives of the internal dosimetry program are to demonstrate that the workplace is under control and that workers are not being exposed to radioactive material, and to detect and assess inadvertent intakes in the workplace. The Savannah River Site Internal Dosimetry Technical Basis Manual (TBM) is intended to provide a technical and philosophical discussion of the radiobioassay and dose assessment aspects of the internal dosimetry program. Detailed information on air, surface, and personal contamination surveillance programs is not given in this manual except for how these programs interface with routine and special bioassay programs.

Not Available

1990-12-20

293

Polyvinyltoluene scintillators for relative ion dosimetry: an investigation with Helium, Carbon and Neon beams.  

E-print Network

and the relative dose. Keywords: Scintillation detectors, dosimetry, ion radiation effects, ion the beam or to monitor the dose during irradiation: ionisation chambers, nuclear tracks detectors with Helium, Carbon and Neon beams. David Broggio et al. 2 I. Introduction Different kinds of radiation

Boyer, Edmond

294

Dosimetry challenges for implementing emerging technologies  

NASA Astrophysics Data System (ADS)

During the last 10 years, radiation therapy technologies have gone through major changes, mainly related introduction of sophisticated delivery and imaging techniques to improve the target localization accuracy and dose conformity. While implementation of these emerging technologies such as image-guided SRS/SBRT, IMRT/IMAT, IGRT, 4D motion management, and special delivery technologies showed substantial clinical gains for patient care, many other factors, such as training/quality, efficiency/efficacy, and cost/effectiveness etc. remain to be challenging. This talk will address technical challenges for dosimetry verification of implementing these emerging technologies in radiation therapy.

Yin, Fang-Fang; Oldham, Mark; Cai, Jing; Wu, Qiuwen

2010-11-01

295

A CUDA Monte Carlo simulator for radiation therapy dosimetry based on Geant4  

NASA Astrophysics Data System (ADS)

Geant4 is a large-scale particle physics package that facilitates every aspect of particle transport simulation. This includes, but is not limited to, geometry description, material definition, tracking of particles passing through and interacting with matter, storage of event data, and visualization. As more detailed and complex simulations are required in different application domains, there is much interest in adapting the code for parallel and multi-core architectures. Parallelism can be achieved by tracking many particles at the same time. The complexity in the context of a GPU/CUDA adaptation is the highly serialized nature of the Geant4 package and the presence of large lookup tables that guide the simulation. This work presents G4CU, a CUDA implementation of the core Geant4 algorithm adapted for dose calculations in radiation therapy. For these applications the geometry is a block of voxels and the physics is limited to low energy electromagnetic physics. These features allow efficient tracking of many particles in parallel on the GPU. Experiments with radiotherapy simulations in G4CU demonstrate about 40 times speedups over Geant4.

Henderson, N.; Murakami, K.; Amako, K.; Asai, M.; Aso, T.; Dotti, A.; Kimura, A.; Gerritsen, M.; Kurashige, H.; Perl, J.; Sasaki, T.

2014-06-01

296

A reference radiation facility for dosimetry at flight altitude and in space.  

PubMed

A reference facility for the intercomparison of active and passive detectors in high-energy neutron fields is available at CERN since 1993. A positive charged hadron beam (a mixture of protons and pions) with momentum of 120 GeV/c hits a copper target, 50 cm thick and 7 cm in diameter. The secondary particles produced in the interaction are filtered by a shielding of either 80 cm of concrete or 40 cm of iron. Behind the iron shielding, the resulting neutron spectrum has a maximum at about 1 MeV, with an additional high-energy component. Behind the concrete shielding, the neutron spectrum has a pronounced maximum at about 70 MeV and resembles the high-energy component of the radiation field created by cosmic rays at commercial flight altitudes. The facility is used for a variety of investigations with active and passive neutron dosimeters. Its use for measurements related to the space programme is discussed. PMID:11770525

Ferrari, A; Mitaroff, A; Silari, M

2001-01-01

297

Image guidance during breast radiotherapy: a phantom dosimetry and radiation-induced second cancer risk study  

NASA Astrophysics Data System (ADS)

Imaging procedures utilised for patient position verification during breast radiotherapy can add a considerable dose to organs surrounding the target volume on top of therapeutic scatter dose. This study investigated the dose from a breast kilovoltage cone-beam CT (kV-CBCT), a breast megavoltage fan-beam CT (MV-FBCT), and a TomoDirectTM breast treatment. Thermoluminescent dosimeters placed within a female anthropomorphic phantom were utilised to measure the dose to various organs and tissues. The contralateral breast, lungs and heart received 0.40 cGy, 0.45 cGy and 0.40 cGy from the kV-CBCT and 1.74 cGy, 1.39 cGy and 1.73 cGy from the MV-FBCT. In comparison to treatment alone, daily imaging would increase the contralateral breast, contralateral lung and heart dose by a relative 12%, 24% and 13% for the kV-CBCT, and 52%, 101% and 58% for the MV-FBCT. The impact of the imaging dose relative to the treatment dose was assessed with linear and linear-quadratic radiation-induced secondary cancer risk models for the contralateral breast. The additional imaging dose and risk estimates presented in this study should be taken into account when considering an image modality and frequency for patient position verification protocols in breast radiotherapy.

Quinn, A.; Holloway, L.; Metcalfe, P.

2013-06-01

298

REVIEW ARTICLE: Perturbation effects in dosimetry: Part I. Kilovoltage x-rays and electrons  

NASA Astrophysics Data System (ADS)

Perturbation effects are defined as departures from ideal large-detector or Bragg - Gray cavity behaviour. Such effects are central to the use of practical dosimeters for accurate dose determination, as is required in external-beam radiotherapy. A theoretical framework for treating perturbation effects is established. In this first part of the review, perturbation in kilovoltage x-ray and megavoltage electron beams are treated in detail, with the emphasis on ionization chambers. The displacement factor for ion chambers in kilovoltage x-ray beams is discussed, starting with the early, pioneering work of Lamerton and Lidén. The evidence for the large values of the perturbation factor in medium-energy x-ray beams (between 100 and 300 kV) recommended in the 1987 IAEA dosimetry code is critically examined and revised, smaller values are given. In electron beams the theoretical approaches to the correction for the in-scattering correction in gas-filled cavities is discussed in detail. The evidence for negligible perturbation in low-energy electron beams in plane-parallel chambers with adequate guard-ring widths is critically reviewed, including the suggested correction for perturbation due to backscattering differences between the chamber-wall material and the medium. The various models for the response of thermoluminescent dosimeters in electron beams are discussed. It is concluded that Monte Carlo simulation of dosimeter response is likely to play an even bigger role in the future.

Nahum, A. E.

1996-09-01

299

Dosimetry at the Los Alamos Critical Experiments Facility: Past, present, and future  

SciTech Connect

Although the primary reason for the existence of the Los Alamos Critical Experiments Facility is to provide basic data on the physics of systems of fissile material, the physical arrangements and ability to provide sources of radiation have led to applications for all types of radiation dosimetry. In the broad definition of radiation phenomena, the facility has provided sources to evaluate biological effects, radiation shielding and transport, and measurements of basic parameters such as the evaluation of delayed neutron parameters. Within the last 15 years, many of the radiation measurements have been directed to calibration and intercomparison of dosimetry related to nuclear criticality safety. Future plans include (1) the new applications of Godiva IV, a bare-metal pulse assembly, for dosimetry (including an evaluation of neutron and gamma-ray room return); (2) a proposal to relocate the Health Physics Research Reactor from the Oak Ridge National Laboratory to Los Alamos, which will provide the opportunity to continue the application of a primary benchmark source to radiation dosimetry; and (3) a proposal to employ SHEBA, a low-enrichment solution assembly, for accident dosimetry and evaluation.

Malenfant, R.E.

1993-10-01

300

Radiation-induced cardiovascular effects  

NASA Astrophysics Data System (ADS)

Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

Tapio, Soile

301

Pharmacokinetics, Metabolism, Biodistribution, Radiation Dosimetry, and Toxicology of 18F-Fluoroacetate (18F-FACE) in Non-human Primates  

PubMed Central

Introduction To facilitate the clinical translation of 18F-fluoroacetate (18F-FACE), the pharmacokinetics, biodistribution, radiolabeled metabolites, radiation dosimetry, and pharmacological safety of diagnostic doses of 18F-FACE were determined in non-human primates. Methods 18F-FACE was synthesized using a custom-built automated synthesis module. Six rhesus monkeys (three of each sex) were injected intravenously with 18F-FACE (165.4± 28.5 MBq), followed by dynamic positron emission tomography (PET) imaging of the thoracoabdominal area during 0–30 min post-injection and static whole-body PET imaging at 40, 100, and 170 min. Serial blood samples and a urine sample were obtained from each animal to determine the time course of 18F-FACE and its radiolabeled metabolites. Electrocardiograms and hematology analyses were obtained to evaluate the acute and delayed toxicity of diagnostic dosages of 18F-FACE. The time-integrated activity coefficients for individual source organs and the whole body after administration of 18F-FACE were obtained using quantitative analyses of dynamic and static PET images and were extrapolated to humans. Results The blood clearance of 18F-FACE exhibited bi-exponential kinetics with half-times of 4 and 250 min for the fast and slow phases, respectively. A rapid accumulation of 18F-FACE-derived radioactivity was observed in the liver and kidneys, followed by clearance of the radioactivity into the intestine and the urinary bladder. Radio-HPLC analyses of blood and urine samples demonstrated that 18F-fluoride was the only detectable radiolabeled metabolite at the level of less than 9% of total radioactivity in blood at 180 min after the 18F-FACE injection. The uptake of free 18F-fluoride in the bones was insignificant during the course of the imaging studies. No significant changes in ECG, CBC, liver enzymes, or renal function were observed. The estimated effective dose for an adult human is 3.90–7.81 mSv from the administration of 185–370 MBq of 18F-FACE. Conclusions The effective dose and individual organ radiation absorbed doses from administration of a diagnostic dosage of 18F-FACE are acceptable. From a pharmacologic perspective, diagnostic dosages of 18F-FACE are non-toxic in primates and, therefore, could be safely administered to human patients for PET imaging. PMID:21437735

Nishii, Ryuichi; Tong, William; Wendt, Richard; Soghomonyan, Suren; Mukhopadhyay, Uday; Balatoni, Julius; Mawlawi, Osama; Bidaut, Luc; Tinkey, Peggy; Borne, Agatha; Alauddin, Mian; Gonzalez-Lepera, Carlos; Yang, Bijun; Gelovani, Juri G.

2014-01-01

302

Radiation Effects on Spacecraft & Aircraft  

Microsoft Academic Search

Satellite systems are vulnerable to Space Weather through its influence on energetic charged particle and plasma populations, which produce a variety of effects, including total dose, lattice displacement damage, single event effects (SEE), noise in sensors and electrostatic charging. In addition aircraft electronics and aircrew are subjected to atmospheric secondary radiation produced by cosmic rays and solar particle events. European

Clive Dyer

2001-01-01

303

Evaluating noncancer effects of trichloroethylene: dosimetry, mode of action, and risk assessment.  

PubMed Central

Alternatives for developing chronic exposure limits for noncancer effects of trichloroethylene (TCE) were evaluated. These alternatives were organized within a framework for dose-response assessment--exposure:dosimetry (pharmacokinetics):mode of action (pharmacodynamics): response. This framework provides a consistent structure within which to make scientific judgments about available information, its interpretation, and use. These judgments occur in the selection of critical studies, internal dose metrics, pharmacokinetic models, approaches for interspecies extrapolation of pharmacodynamics, and uncertainty factors. Potentially limiting end points included developmental eye malformations, liver effects, immunotoxicity, and kidney toxicity from oral exposure and neurological, liver, and kidney effects by inhalation. Each end point was evaluated quantitatively using several methods. Default analyses used the traditional no-observed adverse effect level divided by uncertainty factors and the benchmark dose divided by uncertainty factors methods. Subsequently, mode-of-action and pharmacokinetic information were incorporated. Internal dose metrics were estimated using a physiologically based pharmacokinetic (PBPK) model for TCE and its major metabolites. This approach was notably useful with neurological and kidney toxicities. The human PBPK model provided estimates of human exposure doses for the internal dose metrics. Pharmacodynamic data or default assumptions were used for interspecies extrapolation. For liver and neurological effects, humans appear no more sensitive than rodents when internal dose metrics were considered. Therefore, the interspecies uncertainty factor was reduced, illustrating that uncertainty factors are a semiquantitative approach fitting into the organizational framework. Incorporation of pharmacokinetics and pharmacodynamics can result in values that differ significantly from those obtained with the default methods. PMID:10807562

Barton, H A; Clewell, H J

2000-01-01

304

Harmful effects of ultraviolet radiation  

SciTech Connect

Tanning for cosmetic purposes by sunbathing or by using artificial tanning devices is widespread. The hazards associated with exposure to ultraviolet radiation are of concern to the medical profession. Depending on the amount and form of the radiation, as well as on the skin type of the individual exposed, ultraviolet radiation causes erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity. Skin cancers most commonly produced by ultraviolet radiation are basal and squamous cell carcinomas. There also is much circumstantial evidence that the increase in the incidence of cutaneous malignant melanoma during the past half century is related to increased sun exposure, but this has not been proved. Effective and cosmetically acceptable sunscreen preparations have been developed that can do much to prevent or reduce most harmful effects to ultraviolet radiation if they are applied properly and consistently. Other safety measures include (1) minimizing exposure to ultraviolet radiation, (2) being aware of reflective surfaces while in the sun, (3) wearing protective clothing, (4) avoiding use of artificial tanning devices, and (5) protecting infants and children.

Not Available

1989-07-21

305

Reactor Dosimetry State of the Art 2008  

NASA Astrophysics Data System (ADS)

Oral session 1: Retrospective dosimetry. Retrospective dosimetry of VVER 440 reactor pressure vessel at the 3rd unit of Dukovany NPP / M. Marek ... [et al.]. Retrospective dosimetry study at the RPV of NPP Greifswald unit 1 / J. Konheiser ... [et al.]. Test of prototype detector for retrospective neutron dosimetry of reactor internals and vessel / K. Hayashi ... [et al.]. Neutron doses to the concrete vessel and tendons of a magnox reactor using retrospective dosimetry / D. A. Allen ... [et al.]. A retrospective dosimetry feasibility study for Atucha I / J. Wagemans ... [et al.]. Retrospective reactor dosimetry with zirconium alloy samples in a PWR / L. R. Greenwood and J. P. Foster -- Oral session 2: Experimental techniques. Characterizing the Time-dependent components of reactor n/y environments / P. J. Griffin, S. M. Luker and A. J. Suo-Anttila. Measurements of the recoil-ion response of silicon carbide detectors to fast neutrons / F. H. Ruddy, J. G. Seidel and F. Franceschini. Measurement of the neutron spectrum of the HB-4 cold source at the high flux isotope reactor at Oak Ridge National Laboratory / J. L. Robertson and E. B. Iverson. Feasibility of cavity ring-down laser spectroscopy for dose rate monitoring on nuclear reactor / H. Tomita ... [et al.]. Measuring transistor damage factors in a non-stable defect environment / D. B. King ... [et al.]. Neutron-detection based monitoring of void effects in boiling water reactors / J. Loberg ... [et al.] -- Poster session 1: Power reactor surveillance, retrospective dosimetry, benchmarks and inter-comparisons, adjustment methods, experimental techniques, transport calculations. Improved diagnostics for analysis of a reactor pulse radiation environment / S. M. Luker ... [et al.]. Simulation of the response of silicon carbide fast neutron detectors / F. Franceschini, F. H. Ruddy and B. Petrovi?. NSV A-3: a computer code for least-squares adjustment of neutron spectra and measured dosimeter responses / J. G. Williams, A. P. Ribaric and T. Schnauber. Agile high-fidelity MCNP model development techniques for rapid mechanical design iteration / J. A. Kulesza.Extension of Raptor-M3G to r-8-z geometry for use in reactor dosimetry applications / M. A. Hunter, G. Longoni and S. L. Anderson. In vessel exposure distributions evaluated with MCNP5 for Atucha II / J. M. Longhino, H. Blaumann and G. Zamonsky. Atucha I nuclear power plant azimutal ex-vessel flux profile evaluation / J. M. Longhino ... [et al.]. UFTR thermal column characterization and redesign for maximized thermal flux / C. Polit and A. Haghighat. Activation counter using liquid light-guide for dosimetry of neutron burst / M. Hayashi ... [et al.]. Control rod reactivity curves for the annular core research reactor / K. R. DePriest ... [et al.]. Specification of irradiation conditions in VVER-440 surveillance positions / V. Kochkin ... [et al.]. Simulations of Mg-Ar ionisation and TE-TE ionisation chambers with MCNPX in a straightforward gamma and beta irradiation field / S. Nievaart ... [et al.]. The change of austenitic stainless steel elements content in the inner parts of VVER-440 reactor during operation / V. Smutný, J. Hep and P. Novosad. Fast neutron environmental spectrometry using disk activation / G. Lövestam ... [et al.]. Optimization of the neutron activation detector location scheme for VVER-lOOO ex-vessel dosimetry / V. N. Bukanov ... [et al.]. Irradiation conditions for surveillance specimens located into plane containers installed in the WWER-lOOO reactor of unit 2 of the South-Ukrainian NPP / O. V. Grytsenko. V. N. Bukanov and S. M. Pugach. Conformity between LRO mock-ups and VVERS NPP RPV neutron flux attenuation / S. Belousov. Kr. Ilieva and D. Kirilova. FLUOLE: a new relevant experiment for PWR pressure vessel surveillance / D. Beretz ... [et al.]. Transport of neutrons and photons through the iron and water layers / M. J. Kost'ál ... [et al.]. Condition evaluation of spent nuclear fuel assemblies from the first-generation nuclear-powered submarines by gamma scanning / A. F. Usatyi. L. A. Serdyuk

Voorbraak, Wim; Debarberis, Luigi; D'Hondt, Pierre; Wagemans, Jan

2009-08-01

306

Radiation effects on human heredity.  

PubMed

In experimental organisms such as fruit flies and mice, increased frequencies in germ cell mutations have been detected following exposure to ionizing radiation. In contrast, there has been no clear evidence for radiation-induced germ cell mutations in humans that lead to birth defects, chromosome aberrations, Mendelian disorders, etc. This situation exists partly because no sensitive and practical genetic marker is available for human studies and also because the number of people exposed to large doses of radiation and subsequently having offspring was small until childhood cancer survivors became an important study population. In addition, the genome of apparently normal individuals seems to contain large numbers of alterations, including dozens to hundreds of nonfunctional alleles. With the number of mutational events in protein-coding genes estimated as less than one per genome after 1 gray (Gy) exposure, it is unsurprising that genetic effects from radiation have not yet been detected conclusively in humans. PMID:23988120

Nakamura, Nori; Suyama, Akihiko; Noda, Asao; Kodama, Yoshiaki

2013-01-01

307

Dosimetry in diagnostic radiology.  

PubMed

Dosimetry is an area of increasing importance in diagnostic radiology. There is a realisation amongst health professionals that the radiation dose received by patients from modern X-ray examinations and procedures can be at a level of significance for the induction of cancer across a population, and in some unfortunate instances, in the acute damage to particular body organs such as skin and eyes. The formulation and measurement procedures for diagnostic radiology dosimetry have recently been standardised through an international code of practice which describes the methodologies necessary to address the diverging imaging modalities used in diagnostic radiology. Common to all dosimetry methodologies is the measurement of the air kerma from the X-ray device under defined conditions. To ensure the accuracy of the dosimetric determination, such measurements need to be made with appropriate instrumentation that has a calibration that is traceable to a standards laboratory. Dosimetric methods are used in radiology departments for a variety of purposes including the determination of patient dose levels to allow examinations to be optimized and to assist in decisions on the justification of examination choices. Patient dosimetry is important for special cases such as for X-ray examinations of children and pregnant patients. It is also a key component of the quality control of X-ray equipment and procedures. PMID:20655679

Meghzifene, Ahmed; Dance, David R; McLean, Donald; Kramer, Hans-Michael

2010-10-01

308

Investigation on the effect of sharp phantom edges on point dose measurement during patient-specific dosimetry with Rapid Arc  

PubMed Central

The objective of this work was to investigate and quantify the effect of sharp edges of the phantom on the point dose measurement during patient-specific dosimetry with Rapid Arc (RA). Ten patients with carcinoma of prostate were randomly selected for this dosimetric study. Rapid Arc plans were generated with 6 MV X-rays in the Eclipse (v 8.6.14) with single arc (clockwise). Dosimetry verification plans were generated for two phantoms (cylindrical and rectangular). The cylindrical phantom was solid water (diameter 34 cm) and the rectangular phantom was a water phantom (25 cm × 25 cm × 10 cm). These phantoms were pre-scanned in computed tomography (CT) machine with cylindrical ionization chamber (FC65) in place. The plans were delivered with Novalis Tx linear accelerator with 6 MV X-rays for both the phantoms separately. The measured dose was compared with the planned dose for both the phantoms. Mean percentage deviation between measured and planned doses was found to be 4.19 (SD 0.82) and 3.63 (SD 0.89) for cylindrical and rectangular phantoms, respectively. No significant dosimetric variation was found due to the geometry (sharp edges) of the phantom. The sharp edges of the phantom do not perturb the patient specific Rapid Arc dosimetry significantly. PMID:24049321

Kinhikar, R. A.; Pandey, V. P.; Jose, Rojas K.; Mahantshetty, U.; Dhote, D. S.; Deshpande, D. D.; Shrivastava, S. K.

2013-01-01

309

20. Ruhm, W. et al. The dosimetry system DS86 and the neutron discrepancy in Hiroshima--historical review, present status, and future options. Radiat. Environ. Biophys. 37, 293310 (1998).  

E-print Network

. Collection of Investigative Reports on Atomic Bomb Disaster 34­35 (Science Council of Japan, Tokyo, 1953). 22. Yamasaki, F. & Sugimoto, A. Collection of Investigative Reports on Atomic Bomb Disaster 18­19 (Science of Atomic Bomb Radiation Dosimetry in Hiroshima And Nagasaki-Final Report Vol. 2 (ed. Roesch, W. C.) 283

Losos, Jonathan B.

310

Cumulative radiation damage and cumulative radiation effect.  

PubMed

Different mathematical formulas capable of replacing CRE have been analyzed. The purpose was to develop an expression which would yield a value identical with CRE for regular treatment schedules, but would represent more clearly and more truthfully the radiation damage of tissue. This quantity has been called cumulative radiation damage (CRD). Its unit is adequately called CRD unit. CRD does not require a separate gap correction, as does CRE, it is easy to use, explicit and unambiguous. CRE, CRD and some other formulas have been compared in different types of radiation therapy. PMID:6316749

Väyrynen, T

1983-01-01

311

UV EFFECTS IN TOOTH ENAMEL AND THEIR POSSIBLE APPLICATION IN EPR DOSIMETRY WITH FRONT TEETH  

PubMed Central

The effects of ultraviolet (UV) radiation on ionizing radiation biodosimetry were studied in human tooth enamel samples using the technique of electron paramagnetic resonance (EPR) in X-band. For samples in the form of grains, UV-specific EPR spectra were spectrally distinct from that produced by exposure to gamma radiation. From larger enamel samples, the UV penetration depth was determined to be in the 60–120 ?m range. The difference in EPR spectra from UV exposure and from exposure to gamma radiation samples was found to be a useful marker of UV equivalent dose (defined as the apparent contribution to the gamma dose in mGy that results from UV radiation absorption) in tooth enamel. This concept was preliminarily tested on front teeth from inhabitants of the region of the Semipalatinsk Nuclear Test Site (Kazakhstan) who might have received some exposure to gamma radiation from the nuclear tests conducted there as well as from normal UV radiation in sunlight. The technique developed here to quantify and subtract the UV contribution to the measured tooth is currently limited to cumulative dose measurements with a component of UV equivalent dose equal to or greater than 300 mGy. PMID:20065706

Sholom, S.; Desrosiers, M.; Chumak, V.; Luckyanov, N.; Simon, S.L.; Bouville, A.

2009-01-01

312

Technical Basis Document for PFP Area Monitoring Dosimetry Program  

SciTech Connect

This document describes the phantom dosimetry used for the PFP Area Monitoring program and establishes the basis for the Plutonium Finishing Plant's (PFP) area monitoring dosimetry program in accordance with the following requirements: Title 10, Code of Federal Regulations (CFR), part 835, ''Occupational Radiation Protection'' Part 835.403; Hanford Site Radiological Control Manual (HSRCM-1), Part 514; HNF-PRO-382, Area Dosimetry Program; and PNL-MA-842, Hanford External Dosimetry Technical Basis Manual.

COOPER, J.R.

2000-04-17

313

Annual Conference on Nuclear and Space Radiation Effects, 15th, University of New Mexico, Albuquerque, N. Mex., July 18-21, 1978, Proceedings  

NASA Technical Reports Server (NTRS)

Radiation effects in MOS devices and circuits are considered along with radiation effects in materials, space radiation effects and spacecraft charging, SGEMP, IEMP, EMP, fabrication of radiation-hardened devices, radiation effects in bipolar devices and circuits, simulation, energy deposition, and dosimetry. Attention is given to the rapid anneal of radiation-induced silicon-sapphire interface charge trapping, cosmic ray induced errors in MOS memory cells, a simple model for predicting radiation effects in MOS devices, the response of MNOS capacitors to ionizing radiation at 80 K, trapping effects in irradiated and avalanche-injected MOS capacitors, inelastic interactions of electrons with polystyrene, the photoelectron spectral yields generated by monochromatic soft X radiation, and electron transport in reactor materials.

Simons, M.

1978-01-01

314

Biodistribution and Radiation Dosimetry of the Serotonin Transporter Ligand 11C-DASB Determined from Human Whole-Body PET  

Microsoft Academic Search

11C-Labeled 3-amino-4-(2-dimethylaminomethylphenylsulfanyl)- benzonitrile (DASB) is a selective radioligand for the in vivo quantitation of serotonin transporters (SERTs) using PET. The goal of this study was to provide dosimetry estimates for 11C- DASB based on human whole-body PET. Methods: Dynamic whole-body PET scans were acquired for 7 subjects after the injection of 669 97 MBq (18.1 2.6 mCi) of 11C-DASB. The

Jian-Qiang Lu; Masanori Ichise; Jeih-San Liow; Subroto Ghose; Doug Vines; Robert B. Innis

315

Radiation effects in spacecraft electronics  

NASA Technical Reports Server (NTRS)

Effects on the internal spacecraft electronics due to exposure to the natural and enhanced space radiation environment will be reviewed. The emphasis will be placed on the description of the nature of both the exposure environment and failure mechanisms in semiconductors. Understanding both the system environment and device effects is critical in the use of laboratory simulation environments to obtain the data necessary to design and qualify components for successful application.

Raymond, James P.

1989-01-01

316

Radiative Effects of Aerosols  

NASA Technical Reports Server (NTRS)

During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

Valero, Francisco P. J.

1996-01-01

317

Radiation effects on eye components  

NASA Astrophysics Data System (ADS)

The most important water-soluble components of the vertebrate eye (lens proteins, aqueous humor, vitreous, hyaluronic acid, ascorbic acid) have been investigated in aqueous solution, after preceding X- or UV-irradiation. Spectroscopic, chromatographic, electrophoretic, hydrodynamic and analytic techniques have been applied, to monitor several radiation damages such as destruction of aromatic and sulfur-containing amino acids, aggregation, crosslinking, dissociation, fragmentation, and partial unfolding. Various substances were found which were able to protect eye components effectively against radiation, some of them being also of medical relevance.

Durchschlag, H.; Fochler, C.; Abraham, K.; Kulawik, B.

1999-08-01

318

[Study on the development of a patient dosimetry gown for interventional cardiology procedures].  

PubMed

In recent years, dose justification and optimization have been attempted in percutaneous coronary intervention (PCI); however, deterministic effects have been reported. To prevent radiation skin injuries in PCI, it is necessary to measure the patient entrance skin dose (ESD), but an accurate dose measurement method has not yet been established. In this study, we developed a dosimetry gown that can measure the ESD during PCI using multiple radiophotoluminescence dosimeters (RPLDs). The RPLDs were placed into 84 pockets that were sewn into a dosimetry gown. Patients wear the original dosimetry gown during the procedures, after which we obtain accurate ESD measurements. We believe that this method using RPLDs and a newly-designed dosimetry gown provides accurate ESD measurements during PCI. We expect this system to become a standard method for measuring ESD during PCI. PMID:25142393

Kato, Mamoru; Chida, Koichi; Moritake, Takashi; Koguchi, Yasuhiro; Kaga, Yuji; Sakamoto, Hajime; Tsukamoto, Atsuko; Kawauchi, Satoru; Matsumoto, Kazuma; Matsumura, Mitsuaki; Oosaka, Hajime; Tosa, Tetsuo

2014-08-01

319

International intercomparison for criticality dosimetry: the case of biological dosimetry.  

PubMed

The Institute of Radiation Protection and Nuclear Safety (IRSN) organized a biological dosimetry international intercomparison with the purpose of comparing (i) dicentrics yield produced in human lymphocytes; (ii) the gamma and neutron dose estimate according to the corresponding laboratory calibration curve. The experimental reactor SILENE was used with different configurations: bare source 4 Gy, lead shield 1 and 2 Gy and a 60Co source 2 Gy. An increasing variation of dicentric yield per cell was observed between participants when there were more damages in the samples. Doses were derived from the observed dicentric rates according to the dose-effect relationship provided by each laboratory. Differences in dicentric rate values are more important than those in the corresponding dose values. The doses obtained by the participants were found to be in agreement with the given physical dose within 20%. The evaluation of the respective gamma and neutron dose was achieved only by four laboratories, with some small variations among them. PMID:15353693

Roy, L; Buard, V; Delbos, M; Durand, V; Paillole, N; Grégoire, E; Voisin, P

2004-01-01

320

Dichromate dosimetry. The effect of acetic acid on the radiolytic reduction yield  

NASA Astrophysics Data System (ADS)

The radiation chemical yield for the reduction of dichromate, Cr(VI) ? Cr 3+, in an acidic aqueous perchloric acid solution of potassium dichromate, may be increased from 0.04 to >0.2 ? mol J -1 by adding acetic acid. The increased yield, G[-(Cr 2O 7) 2-] is about the same in N 2- and O 2-saturated solutions. The molar linear absorption coefficient at 350 nm also is the same in both solutions ( ?m = 2800 M-1cm-1) at pH 0.4. The proposed mechanism to explain the enhanced response in N 2-saturated solutions involves the efficient reaction of acetic acid with hydroxyl radicals by the abstraction of H from the methyl group; the resulting acid radicals react with relatively high yield to reduce Cr(VI). In O 2-saturated solution, the acetic acid radical apparently goes through an acetic acid peroxyl radical by a bimolecular reaction to the tetroxide intermediate of acetic acid, which releases H 2O 2 with relatively high yield by a Bennett-type reaction. This additional H 2O 2, as a reducing agent, reacts slowly with dichromate and boosts the value of G[-(Cr 2O 7) 2-]. The negative slope of the response (? A vs dose) continues to increase during the period immediately after irradiation of oxygenated solution, due to slow reaction of radiolytically-produced H 2O 2 with dichromate. There is also in both O 2- and N 2-saturated solution a long-term slow reaction involving oxidation of the organic substrate (in this case, acetic acid). Because of these instabilities, the solutions cannot readily be used for dosimetry without the presence of silver ions, which in the oxidized state, Ag 2+, act to stabilize the solution after irradiation. The addition of silver dichromate at a concentration of 0.1 mM decreases the yield to G[-(Cr 2O 7) 2-] = 0.17 ?molJ-1, but greatly improves the stability of the solution after irradiation. The absorbed dose range for the modified dichromate dosimeter when analyzed spectrophotometrically at 350 nm wavelength is approx. 2 × 10 2-2 × 10 3 Gy.

Al-Sheikhly, M.; Hussmann, M. H.; McLaughlin, W. L.

321

Effects of nuclear interactions on energy and stopping power in proton beam dosimetry  

Microsoft Academic Search

Most experimental methods for proton beam dosimetry require stopping power values and proton energy distributions in the irradiated materials. At proton energies of interest in radiotherapy, nuclear interactions in biological tissue or in tissue-equivalent materials are not negligible. As a consequence of nuclear interactions the primary proton fluence is attenuated and lower energy secondary protons and other charged particles are

R. F. Laitano; M. Rosetti; M. Frisoni

1996-01-01

322

Evaluation of Effective Sources in Uncertainty Measurements of Personal Dosimetry by a Harshaw TLD System  

PubMed Central

Background: The accurate results of the individual doses in personal dosimety which are reported by the service providers in personal dosimetry are very important. There are national / international criteria for acceptable dosimetry system performance. Objective: In this research, the sources of uncertainties are identified, measured and calculated in a personal dosimetry system by TLD. Method: These sources are included; inhomogeneity of TLDs sensitivity, variability of TLD readings due to limited sensitivity and background, energy dependence, directional dependence, non-linearity of the response, fading, dependent on ambient temperature / humidity and calibration errors, which may affect on the dose responses. Some parameters which influence on the above sources of uncertainty are studied for Harshaw TLD-100 cards dosimeters as well as the hot gas Harshaw 6600 TLD reader system. Results: The individual uncertainties of each sources was measured less than 6.7% in 68% confidence level. The total uncertainty was calculated 17.5% with 95% confidence level. Conclusion: The TLD-100 personal dosimeters as well as the Harshaw TLD-100 reader 6600 system show the total uncertainty value which is less than that of admissible value of 42% for personal dosimetry services. PMID:25505769

Hosseini Pooya, SM; Orouji, T

2014-01-01

323

Effect of Edema on Postimplant Dosimetry in Prostate Brachytherapy Using CT/MRI Fusion  

SciTech Connect

Purpose: To investigate the time course of prostatic edema and the effect on the dose-volume histograms of the prostate for patients treated with brachytherapy. Methods and Materials: A total of 74 patients with prostate cancer were enrolled in this prospective study. A transrectal ultrasound-based preplan was performed 4 weeks before implantation and computed tomography/magnetic resonance imaging fusion-based postimplant dosimetry was performed on the day after implantation (Day 1) and 30 days after implantation (Day 30). The prostate volume, prostate volume covered by 100% of the prescription dose (V{sub 100}), and dose covering 90% of the prostate (D{sub 90}) were evaluated with prostatic edema over time. Results: Prostatic edema was greatest on Day 1, with the mean prostate volume 36% greater than the preplan transrectal ultrasound-based volume; it thereafter decreased over time. It was 9% greater than preplan volume on Day 30. The V{sub 100} increased 5.7% from Day 1 to Day 30, and the D{sub 90} increased 13.1% from Day 1 to Day 30. The edema ratio (postplan/preplan) on Day 1 of low-quality implants with a V{sub 100} of <80% was significantly greater than that of intermediate- to high-quality implants (>80% V{sub 100}; p = 0.0272). The lower V{sub 100} on Day 1 showed a greater increase from Day 1 to Day 30. A V{sub 100} on Day 1 of >92% is unlikely to increase >0% during the interval studied. Conclusion: Low-quality implants on Day 1 were highly associated with edema; however, such a low-quality implant on Day 1, with significant edema, tended to improve by Day 30. If a high-quality implant (V100 >92%) can be obtained on Day 1, a re-examination is no longer necessary.

Tanaka, Osamu [Department of Radiology, Gifu University School of Medicine, Gifu (Japan); Division of Radiation Oncology, Gifu University Hospital, Gifu City (Japan)], E-mail: osa-mu@umin.ac.jp; Hayashi, Shinya; Matsuo, Masayuki [Department of Radiology, Gifu University School of Medicine, Gifu (Japan); Division of Radiation Oncology, Gifu University Hospital, Gifu City (Japan); Nakano, Masahiro; Uno, Hiromi [Department of Urology, Gifu University School of Medicine, Gifu (Japan); Ohtakara, Kazuhiro [Department of Radiology, Gifu University School of Medicine, Gifu (Japan); Division of Radiation Oncology, Gifu University Hospital, Gifu City (Japan); Miyoshi, Toshiharu [Division of Radiation Oncology, Gifu University Hospital, Gifu City (Japan); Deguchi, Takashi [Department of Urology, Gifu University School of Medicine, Gifu (Japan); Hoshi, Hiroaki [Department of Radiology, Gifu University School of Medicine, Gifu (Japan)

2007-10-01

324

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

NASA Astrophysics Data System (ADS)

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

Garcia, Tristan; Anton, Mathias; Sharpe, Peter

2012-01-01

325

The importance of 3D dosimetry  

NASA Astrophysics Data System (ADS)

Radiation therapy has been getting progressively more complex for the past 20 years. Early radiation therapy techniques needed only basic dosimetry equipment; motorized water phantoms, ionization chambers, and basic radiographic film techniques. As intensity modulated radiation therapy and image guided therapy came into widespread practice, medical physicists were challenged with developing effective and efficient dose measurement techniques. The complex 3-dimensional (3D) nature of the dose distributions that were being delivered demanded the development of more quantitative and more thorough methods for dose measurement. The quality assurance vendors developed a wide array of multidetector arrays that have been enormously useful for measuring and characterizing dose distributions, and these have been made especially useful with the advent of 3D dose calculation systems based on the array measurements, as well as measurements made using film and portal imagers. Other vendors have been providing 3D calculations based on data from the linear accelerator or the record and verify system, providing thorough evaluation of the dose but lacking quality assurance (QA) of the dose delivery process, including machine calibration. The current state of 3D dosimetry is one of a state of flux. The vendors and professional associations are trying to determine the optimal balance between thorough QA, labor efficiency, and quantitation. This balance will take some time to reach, but a necessary component will be the 3D measurement and independent calculation of delivered radiation therapy dose distributions.

Low, Daniel

2015-01-01

326

Neutron personnel dosimetry  

SciTech Connect

The current state-of-the-art in neutron personnel dosimetry is reviewed. Topics covered include dosimetry needs and alternatives, current dosimetry approaches, personnel monitoring devices, calibration strategies, and future developments. (ACR)

Griffith, R.V.

1981-06-16

327

A method applicable to effective dose rate estimates for aircrew dosimetry.  

PubMed

The inclusion of cosmic radiation as occupational exposure under ICRP Publication 60 and the European Union Council Directive 96/29/Euratom has highlighted the need to estimate the exposure of aircrew. According to a report of the Group of Experts established under the terms of Article 31 of the European Treaty, the individual estimates of dose for flights below 15 km may be done using an appropriate computer program. In order to calculate the radiation exposure at aircraft altitudes, calculations have been performed by means of the Monte Carlo transport code FLUKA. On the basis of the calculated results, a simple method is proposed for the individual evaluation of effective dose rate due to the galactic component of cosmic radiation as a function of latitude and altitude. PMID:11586734

Ferrari, A; Pelliccioni, M; Rancati, T

2001-01-01

328

The effects of incidence angle on film dosimetry and their consequences in IMRT dose verification  

SciTech Connect

Purpose: The dosimetric accuracy of EDR2 radiographic film has been rigorously assessed in regular and intensity modulated beams for various incidence angles, including the parallel and perpendicular orientation. There clearly exists confusion in literature regarding the effect of film orientation. The primary aim is to clarify potential sources of the confusion and to gain physical insight into the film orientation effect with a link to radiochromic film as well. Methods: An inverse pyramid IMRT field, consisting of six regular and elongated 3 Multiplication-Sign 20 cm{sup 2} field segments, was studied in perpendicular and parallel orientation. Assessment of film self-perturbation and intrinsic directional sensitivity were also included in the experiments. Finally, the authors investigated the orientational effect in composite beams in the two extreme orientations, i.e., perpendicular and parallel. Results: The study of an inverse pyramid dose profile revealed good agreement between the perpendicular film and the diamond detector within 0.5% in the low-scatter regions for both 6 and 18 MV. The parallel oriented film demonstrated a 3% under-response at 5-cm (6 MV) depth against the perpendicular orientation, but both orientations over responded equally in the central region, which received only scattered dose, at both 5- and 20-cm depths. In a regular 6-MV 5 Multiplication-Sign 5 cm{sup 2} field, a 4.1% lower film response was observed in the parallel orientation compared to perpendicular orientation. The under response gradually increased to 6% when reducing the field size to 0.5 Multiplication-Sign 5 cm{sup 2}. On the other hand, the film showed a 1.7% lower response in parallel orientation for the large field size of 20 Multiplication-Sign 20 cm{sup 2} at 5-cm depth but the difference disappeared at 10 cm. At 18 MV, similar but somewhat lower differences were found between the two orientations. The directional sensitivity of the film diminishes with increasing field size and depth. Surprisingly a composite IMRT beam consisting of 20 adjacent strip segments also produced a significant orientational dependence of film response, notwithstanding the large total field size of 20 Multiplication-Sign 20 cm{sup 2}. Conclusions: This analysis allowed the development of a hypothesis about the physics behind the orientational dependence of film response in general and to formulate precautions when using film dosimetry in the dosimetric verification of multibeam treatments.

Srivastava, R. P.; De Wagter, C. [Department of Radiation Oncology and Experimental Cancer Research, Ghent University Hospital, De Pintelaan 185, 9000 Gent (Belgium)

2012-10-15

329

Geant4 electromagnetic physics updates for space radiation effects simulation  

NASA Astrophysics Data System (ADS)

The Geant4 toolkit is used in many applications including space science studies. The new Geant4 version 10.0 released in December 2013 includes a major revision of the toolkit and offers multi-threaded mode for event level parallelism. At the same time, Geant4 electromagnetic and hadronic physics sub-libraries have been significantly updated. In order to validate the new and updated models Geant4 verification tests and benchmarks were extended. Part of these developments was sponsored by the European Space Agency in the context of research aimed at modelling radiation biological end effects. In this work, we present an overview of results of several benchmarks for electromagnetic physics models relevant to space science. For electromagnetic physics, recently Compton scattering, photoelectric effect, and Rayleigh scattering models have been improved and extended down to lower energies. Models of ionization and fluctuations have also been improved; special micro-dosimetry models for Silicon and liquid water were introduced; the main multiple scattering model was consolidated; and the atomic de-excitation module has been made available to all models. As a result, Geant4 predictions for space radiation effects obtained with different Physics Lists are in better agreement with the benchmark data than previous Geant4 versions. Here we present results of electromagnetic tests and models comparison in the energy interval 10 eV - 10 MeV.

Ivantchenko, Anton; Nieminen, Petteri; Incerti, Sebastien; Santin, Giovanni; Ivantchenko, Vladimir; Grichine, Vladimir; Allison, John; Karamitos, Mathiew

330

Radiation dosimetry estimation of N-(2-[(18)F]fluoropropionyl)- l-glutamate based on the mice distribution data.  

PubMed

N-(2-[(18)F]fluoropropionyl)-l-glutamate([(18)F]FPGLU) was a recently developed potential amino acid tracer for tumor imaging with positron emission tomography-computer tomography (PET-CT). The absorbed and effective radiation doses resulting from the intravenous administration of [(18)F]FPGLU were estimated using biodistribution data from normal mice. The methodology recommended by Medical Internal Radiation Dose Committee (MIRD) was used to estimate the doses. The highest uptake of [(18)F]FPGLU was found in the kidneys, followed by the liver and lung. The kidneys were the organ received the highest absorbed dose, 58.4?Gy/MBq, the brain received the lowest dose, 5.5?Gy/MBq, and other organs received doses in the range of 8.3-11.9?Gy/MBq. The effective dose was 17.0?Sv/MBq. The data show that a 370MBq (10mCi) injection of [(18)F]FPGLU would lead to an estimated effective dose of 6.3mSv, which is within the accepted range of routine nuclear medicine investigations. PMID:25661723

Tang, Caihua; Xu, Zeqing; Hu, Kongzhen; Yao, Baoguo; Tang, Ganghua; Nie, Dahong

2015-04-01

331

Extension of the biological effective dose to the MIRD schema and possible implications in radionuclide therapy dosimetry  

SciTech Connect

In dosimetry-based treatment planning protocols, patients with rapid clearance of the radiopharmaceutical require a larger amount of initial activity than those with slow clearance to match the absorbed dose to the critical organ. As a result, the dose-rate to the critical organ is higher in patients with rapid clearance and may cause unexpected toxicity compared to patients with slow clearance. In order to account for the biological impact of different dose-rates, radiobiological modeling is beginning to be applied to the analysis of radionuclide therapy patient data. To date, the formalism used for these analyses is based on kinetics derived from activity in a single organ, the target. This does not include the influence of other source organs to the dose and dose-rate to the target organ. As a result, only self-dose irradiation in the target organ contributes to the dose-rate. In this work, the biological effective dose (BED) formalism has been extended to include the effect of multiple source organ contributions to the net dose-rate in a target organ. The generalized BED derivation has been based on the Medical Internal Radionuclide Dose Committee (MIRD) schema assuming multiple source organs following exponential effective clearance of the radionuclide. A BED-based approach to determine the largest safe dose to critical organs has also been developed. The extended BED formalism is applied to red marrow dosimetry, as well as kidney dosimetry considering the cortex and the medulla separately, since both those organs are commonly dose limiting in radionuclide therapy. The analysis shows that because the red marrow is an early responding tissue (high {alpha}/{beta}), it is less susceptible to unexpected toxicity arising from rapid clearance of high levels of administered activity in the marrow or in the remainder of the body. In kidney dosimetry, the study demonstrates a complex interplay between clearance of activity in the cortex and the medulla, as well as the initial activity ratio and the S value ratio between the two. In some scenarios, projected BED based on both the cortex and the medulla is a more appropriate constraint on the administered activity than the BED based on the cortex only. Furthermore, different fractionated regimens were considered to reduce renal toxicity. The MIRD-based BED formalism is expected to be useful for patient-specific adjustments of activity and to facilitate the investigation of dose-toxicity correlations with respect to dose-rate and tissue repair mechanism.

Baechler, Sebastien; Hobbs, Robert F.; Prideaux, Andrew R.; Wahl, Richard L.; Sgouros, George [Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21231 (United States) and University Institute of Radiation Physics (IRA-DUMSC), University of Lausanne, Lausanne (Switzerland); Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21231 (United States)

2008-03-15

332

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at the U.S. Department of Energy (DOE) Hanford site. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with requirements of 10 CFR 835, the DOE Laboratory Accreditation Program, the DOE Richland Operations Office, DOE Office of River Protection, DOE Pacific Northwest Office of Science, and Hanford’s DOE contractors. The dosimetry system is operated by the Pacific Northwest National Laboratory (PNNL) Hanford External Dosimetry Program which provides dosimetry services to PNNL and all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document. Maintenance and distribution of controlled hard copies of the manual by PNNL was discontinued beginning with Revision 0.2.

Rathbone, Bruce A.

2011-04-04

333

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at the U.S. Department of Energy (DOE) Hanford site. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with requirements of 10 CFR 835, the DOE Laboratory Accreditation Program, the DOE Richland Operations Office, DOE Office of River Protection, DOE Pacific Northwest Office of Science, and Hanford’s DOE contractors. The dosimetry system is operated by the Pacific Northwest National Laboratory (PNNL) Hanford External Dosimetry Program which provides dosimetry services to PNNL and all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document. Maintenance and distribution of controlled hard copies of the manual by PNNL was discontinued beginning with Revision 0.2.

Rathbone, Bruce A.

2010-04-01

334

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program (HEDP) which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee (HPDAC) which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. Rev. 0 marks the first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database. Revision numbers that are whole numbers reflect major revisions typically involving changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document. Revision Log: Rev. 0 (2/25/2005) Major revision and expansion. Rev. 0.1 (3/12/2007) Minor revision. Updated Chapters 5, 6 and 9 to reflect change in default ring calibration factor used in HEDP dose calculation software. Factor changed from 1.5 to 2.0 beginning January 1, 2007. Pages on which changes were made are as follows: 5.23, 5.69, 5.78, 5.80, 5.82, 6.3, 6.5, 6.29, 9.2.

Rathbone, Bruce A.

2007-03-12

335

Polymer gel dosimetry for neutron beam in the Neutron Exposure Accelerator System for Biological Effect Experiments (NASBEE)  

NASA Astrophysics Data System (ADS)

This study aimed to investigate whether gel dosimetry could be used to measure neutron beams. We irradiated a BANG3-type polymer gel dosimeter using neutron beams in the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) at the National Institute of Radiological Sciences (NIRS) in Japan. First, the polymer gels were irradiated from 0 to 7.0 Gy to investigate the dose-R2 responses. Irradiated gels were evaluated using 1.5-T magnetic resonance R2 images. Second, the polymer gels were irradiated to 1.0, 3.0, and 5.0 Gy to acquire a depth-R2 response curve. The dose-R2 response curve was linear up to approximately 7 Gy, with a slope of 1.25 Gy?1·s?1. Additionally, compared with the photon- irradiated gels, the neutron-irradiated gels had lower R2 values. The acquired depth-R2 curves of the central axis from the 3.0- and 5.0-Gy neutron dose-irradiated gels exhibited an initial build-up. Although, a detailed investigation is needed, polymer gel dosimetry is effective for measuring the dose-related R2 linearity and depth-R2 relationships of neutron beams.

Kawamura, H.; Sato, H.; Hamano, T.; Suda, M.; Yoshii, H.

2015-01-01

336

EFFECT OF RADIOFREQUENCY RADIATION ON THERMOREGULATION  

EPA Science Inventory

In the past 30 years there have been numerous studies on the patho-physiological effects of exposure to radiofrequency (RF) radiation. t is clear that the majority of these effects can be attributed to the thermogenic action of RF radiation. uring exposure to RF radiation the the...

337

RADIATION EFFECTS IN MATERIAL MICROSTRUCTURE.  

SciTech Connect

Next generation nuclear power systems, high-power particle accelerators and space technology will inevitably rely on higher performance materials that will be able to function in the extreme environments of high irradiation, high temperatures, corrosion and stress. The ability of any material to maintain its functionality under exposure to harsh conditions is directly linked to the material structure at the nano- and micro-scales. Understanding of the underlying processes is key to the success of such undertakings. This paper presents experimental results of the effects of radiation exposure on several unique alloys, composites and crystals through induced changes in the physio-mechanical macroscopic properties.

SIMOS,N.

2007-05-30

338

SCIENTIFIC NOTE Variations in daily quality assurance dosimetry from device  

E-print Network

SCIENTIFIC NOTE Variations in daily quality assurance dosimetry from device levelling, feet are effective tools for analysis of daily dosimetry including flatness, symmetry, energy, field size and central these backscattering effects. Keywords Radiotherapy Á Quality assurance Á Dosimetry Á X-rays Introduction Radiotherapy

Yu, K.N.

339

Development of Fast and Highly Efficient Gas Ionization Chamber For Patient Imaging and Dosimetry in Radiation Therapy  

SciTech Connect

In radiation therapy of cancer, more accurate delivery techniques spur the need for improved patient imaging during treatment. To this purpose, the megavoltage radiation protocol that is used for treatment is also used for imaging.

R. Hinderler; H. Keller; T.R. Mackie; M.L. Corradini

2003-09-08

340

Handbook of Anatomical Models for Radiation Dosimetry (To be published in 2009 in "Series in Medical Physics and Biomedical Engineering")  

E-print Network

Family Maria Zankl Chapter 4 The ADELAIDE Teenage Female Voxel Computational Phantom Martin Caon in External Beam Radiation Therapy Harald Paganetti Chapter 26 Image-Guided Radiation Treatment Planning

Linhardt, Robert J.

341

Consistency of external dosimetry in epidemiologic studies of nuclear workers  

SciTech Connect

To make the best use of available epidemiologic data in assessing risks from exposure to low-level radiation, it is important that biases and uncertainties in estimated doses be understood and documented. With this understanding, analyses of mortality data can be strengthened by including the use of correction factors where judged appropriate, excluding portions of the data where uncertainty in dose estimates is judged to be very large, and conducting sensitivity analyses to examine the effect of alternative assumptions about dosimetry errors and biases on results. It is hoped that the pooling of data from several epidemiologic studies and improved understanding of dosimetry will lead to better estimates of radiation risks. 10 refs., 4 tabs.

Fix, J.J.; Gilbert, E.S.

1991-10-01

342

Status of neutron dosimetry cross sections  

SciTech Connect

Several new cross section libraries, such as ENDF/B-VI(release 2), IRDF-90,JEF-2.2, and JENDL-3 Dosimetry, have recently been made available to the dosimetry community. the Sandia National Laboratories (SNL) Radiation Metrology Laboratory (RML) has worked with these libraries since pre-release versions were available. this paper summarizes the results of the intercomparison and testing of dosimetry cross sections. As a result of this analysis, a compendium of the best dosimetry cross sections was assembled from the available libraries for use within the SNL RML. this library, referred to as the SNLRML Library, contains 66 general dosimetry sensors and 3 special dosimeters unique to the RML sensor inventory. The SNLRML cross sections have been put into a format compatible with commonly used spectrum determination codes.

Griffin, P.J.; Kelly, J.G.

1992-12-31

343

Joint USNRC/EC consequence uncertainty study: The ingestion pathway, dosimetry and health effects expert judgment elicitations and results  

SciTech Connect

The US Nuclear Regulatory Commission (USNRC) and the European Commission (EC) have conducted a formal expert judgment elicitation jointly to systematically collect the quantitative information needed to perform consequence uncertainty analyses on a broad set of commercial nuclear power plants. Information from three sets of joint US/European expert panels was collected and processed. Information from the three sets of panels was collected in the following areas: in the phenomenological areas of atmospheric dispersion and deposition, in the areas of ingestion pathways and external dosimetry, and in the areas of health effects and internal dosimetry. This exercise has demonstrated that the uncertainty for particular issues as measured by the ratio of the 95th percentile to the 5th percentile can be extremely large (orders of magnitude), or rather small (factor of two). This information has already been used by many of the experts that were involved in this process in areas other than the consequence uncertainty field. The benefit to the field of radiological consequences is just beginning as the results of this study are published and made available to the consequence community.

Harper, F. [Sandia National Labs., Albuquerque, NM (United States); Goossens, L. [Delft Univ. of Technology (Netherlands); Abbott, M. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States)] [and others

1996-08-01

344

Effect of lateral radiative losses on radiative shock propagation  

NASA Astrophysics Data System (ADS)

Experimental and numerical studies of radiative shocks, of interest as scaled astrophysical objects, have been performed. Experiments were conducted at the PALS facility in Prague with a xenon filled mini-shock tube using a laser accelerated plastic pusher. Numerical simulations of the hydrodynamics including radiation effects have been performed with the 3D code HERACLES. Measurements have been made of the electronic density of the shocked gas and of the time history of the position of the radiative precursor. Simulations and experimental results show good agreement when lateral radiative losses are taken into account, including a wall albedo of 40%.

Busquet, M.; Audit, E.; González, M.; Stehlé, C.; Thais, F.; Acef, O.; Bauduin, D.; Barroso, P.; Rus, B.; Kozlova, M.; Polan, J.; Mocek, T.

2007-05-01

345

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program (HEDP) which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee (HPDAC) which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document. Maintenance and distribution of controlled hard copies of the manual by PNNL was discontinued beginning with Revision 0.2. Revision Log: Rev. 0 (2/25/2005) Major revision and expansion. Rev. 0.1 (3/12/2007) Updated Chapters 5, 6 and 9 to reflect change in default ring calibration factor used in HEDP dose calculation software. Factor changed from 1.5 to 2.0 beginning January 1, 2007. Pages on which changes were made are as follows: 5.23, 5.69, 5.78, 5.80, 5.82, 6.3, 6.5, 6.29, and 9.2. Rev 0.2 (8/28/2009) Updated Chapters 3, 5, 6, 8 and 9. Chapters 6 and 8 were significantly expanded. References in the Preface and Chapters 1, 2, 4, and 7 were updated to reflect updates to DOE documents. Approved by HPDAC on 6/2/2009. Rev 1.0 (1/1/2010) Major revision. Updated all chapters to reflect the Hanford site wide implementation on January 1, 2010 of new DOE requirements for occupational radiation protection. The new requirements are given in the June 8, 2007 amendment to 10 CFR 835 Occupational Radiation Protection (Federal Register, June 8, 2007. Title 10 Part 835. U.S., Code of Federal Regulations, Vol. 72, No. 110, 31904-31941). Revision 1.0 to the manual replaces ICRP 26 dosimetry concepts and terminology with ICRP 60 dosimetry concepts and terminology and replaces external dose conversion factors from ICRP 51 with those from ICRP 74 for use in measurement of operational quantities with dosimeters. Descriptions of dose algorithms and dosimeter response characteristics, and field performance were updated to reflect changes in the neutron quality factors used in the measurement of operational quantities.

Rathbone, Bruce A.

2010-01-01

346

Monte Carlo Investigation on the Effect of Heterogeneities on Strut Adjusted Volume Implant (SAVI) Dosimetry  

NASA Astrophysics Data System (ADS)

Breast cancer is the most prevalent cancer for women with more than 225,000 new cases diagnosed in the United States in 2012 (ACS, 2012). With the high prevalence, comes an increased emphasis on researching new techniques to treat this disease. Accelerated partial breast irradiation (APBI) has been used as an alternative to whole breast irradiation (WBI) in order to treat occult disease after lumpectomy. Similar recurrence rates have been found using ABPI after lumpectomy as with mastectomy alone, but with the added benefit of improved cosmetic and psychological results. Intracavitary brachytherapy devices have been used to deliver the APBI prescription. However, inability to produce asymmetric dose distributions in order to avoid overdosing skin and chest wall has been an issue with these devices. Multi-lumen devices were introduced to overcome this problem. Of these, the Strut-Adjusted Volume Implant (SAVI) has demonstrated the greatest ability to produce an asymmetric dose distribution, which would have greater ability to avoid skin and chest wall dose, and thus allow more women to receive this type of treatment. However, SAVI treatments come with inherent heterogeneities including variable backscatter due to the proximity to the tissue-air and tissue-lung interfaces and variable contents within the cavity created by the SAVI. The dose calculation protocol based on TG-43 does not account for heterogeneities and thus will not produce accurate dosimetry; however Acuros, a model-based dose calculation algorithm manufactured by Varian Medical Systems, claims to accurately account for heterogeneities. Monte Carlo simulation can calculate the dosimetry with high accuracy. In this thesis, a model of the SAVI will be created for Monte Carlo, specifically using MCNP code, in order to explore the affects of heterogeneities on the dose distribution. This data will be compared to TG-43 and Acuros calculated dosimetry to explore their accuracy.

Koontz, Craig

347

Solid-State Personal Dosimetry  

NASA Technical Reports Server (NTRS)

This document is a web site page, and a data sheet about Personal protection (i.e., space suits) presented to the Radiation and Micrometeoroid Mitigation Technology Focus Group meeting. The website describes the work of the PI to improve solid state personal radiation dosimetry. The data sheet presents work on the active personal radiation detection system that is to provide real-time local radiation exposure information during EVA. Should undue exposure occur, knowledge of the dynamic intensity conditions during the exposure will allow more precise diagnostic assessment of the potential health risk to the exposed individual.

Wrbanek, John D.; Fralick, Gustave C.; Wrbanek, Susan Y.

2005-01-01

348

Radiation effects in the environment  

SciTech Connect

Although the Navajo possess substantial resource wealth-coal, gas, uranium, water-this potential wealth has been translated into limited permanent economic or political power. In fact, wealth or potential for wealth has often made the Navajo the victims of more powerful interests greedy for the assets under limited Navajo control. The primary focus for this education workshop on the radiation effects in the environment is to provide a forum where scientists from the nuclear science and technology community can share their knowledge toward the advancement and diffusion of nuclear science and technology issues for the Navajo public. The scientists will make an attempt to consider the following basic questions; what is science; what is mathematics; what is nuclear radiation? Seven papers are included in this report: Navajo view of radiation; Nuclear energy, national security and international stability; ABC`s of nuclear science; Nuclear medicine: 100 years in the making; Radon in the environment; Bicarbonate leaching of uranium; and Computational methods for subsurface flow and transport. The proceedings of this workshop will be used as a valuable reference materials in future workshops and K-14 classrooms in Navajo communities that need to improve basic understanding of nuclear science and technology issues. Results of the Begay-Stevens research has revealed the existence of strange and mysterious concepts in the Navajo Language of nature. With these research results Begay and Stevens prepared a lecture entitled The Physics of Laser Fusion in the Navajo language. This lecture has been delivered in numerous Navajo schools, and in universities and colleges in the US, Canada, and Alaska.

Begay, F.; Rosen, L.; Petersen, D.F.; Mason, C.; Travis, B. [Los Alamos National Lab., NM (United States); Yazzie, A. [Navajo Nation, Window Rock, AZ (United States). Dept. of History; Isaac, M.C.P.; Seaborg, G.T. [Lawrence Berkeley National Lab., CA (United States); Leavitt, C.P. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Physics and Astronomy

1999-04-01

349

The artefacts of radiochromic film dosimetry with flatbed scanners and their causation by light scattering from radiation-induced polymers  

NASA Astrophysics Data System (ADS)

Optical experiments and theoretical considerations have been undertaken in order to understand the causes of the ‘orientation effect’ and the ‘parabola effect’, the artefacts impairing the desired light absorption measurement on radiochromic EBT3 films with flatbed scanners. EBT3 films exposed to doses up to 20.9 Gy were scanned with an Epson Expression 10000XL flatbed scanner in landscape and portrait orientation. The horizontally and vertically polarized light components of the scanner were determined, and another Epson Expression 10000XL flatbed scanner was disassembled to examine its optical components. The optical properties of exposed and unexposed EBT3 films were studied with incident polarized and unpolarized white light, and the transmitted red light was investigated for its polarization and scattering properties including the distribution of the scattering angles. Neutral density filters were studied for comparison. Guidance was sought from the theory of light scattering from rod-like macromolecular structures. The drastic dose-dependent variation of the transmitted total light current as function of the orientation of front and rear polarizers, interpreted by light scattering theory, shows that the radiation-induced polymerization of the monomers of EBT3 films produces light scattering oscillators preferably polarized at right angles with the coating direction of the film. The directional distribution of the scattered light is partly anisotropic, with a preferred scattering plane at right angles with the coating direction, indicating light scattering from stacks of coherently vibrating oscillators piled up along the monomer crystals. The polyester carrier film also participates in these effects. The ‘orientation’ and ‘parabola’ artefacts due to flatbed scanning of radiochromic films can be explained by the interaction of the polarization-dependent and anisotropic light scattering from exposed and unexposed EBT3 films with the quantitative difference between the scanner's horizontally and vertically polarized light supply and with the limited directional acceptance of the scanner's light recording system.

Schoenfeld, Andreas A.; Poppinga, Daniela; Harder, Dietrich; Doerner, Karl-Joachim; Poppe, Bjoern

2014-07-01

350

Microbeam Radiation Therapy: Tissue Dose Penetration and BANG-Gel Dosimetry of Thick-Beams' Array Intelacing  

SciTech Connect

The tissue-sparing effect of parallel, thin (narrower than 100em) synchrotron-generated X-ray planar beams (microbeams) in healthy tissues including the central nervous system (CNS) is known since early 1990s. This, together with a remarkable preferential tumoricidal effect of such beam arrays observed at high doses, has been the basis for labeling the method microbeam radiation therapy (MRT). Recent studies showed that beams as thick as 0.68mm ('thick microbeams') retain part of their sparing effect in the rat's CNS, and that two such orthogonal microbeams arrays can be interlaced to produce an unsegmented field at the target, thus producing focal targeting. We measured the half-value layer (HVL) of our 120-keV median-energy beam in water phantoms, and we irradiated stereotactically bis acrylamide nitrogen gelatin (BANG)-gel-filled phantoms, including one containing a human skull, with interlaced microbeams and imaged them with MRI. A 43-mm water HVL resulted, together with an adequately large peak-to-valley ratio of the microbeams' three-dimensional dose distribution in the vicinity of the 20mmx20mmx20mm target deep into the skull. Furthermore, the 80-20% dose falloff was a fraction of a millimeter as predicted by Monte Carlo simulations. We conclude that clinical MRT will benefit from the use of higher beam energies than those used here, although the current energy could serve certain neurosurgical applications. Furthermore, thick microbeams particularly when interlaced present some advantages over thin microbeams in that they allow the use of higher beam energies and they could conceivably be implemented with high power orthovoltage X-ray tubes.

Dilmanian, F.; Romanelli, P; Zhong, Z; Wang, R; Wagshul, M; Kalef-Ezra, J; Maryanski, M; Rosen, E; Anschel, D

2008-01-01

351

The artefacts of radiochromic film dosimetry with flatbed scanners and their causation by light scattering from radiation-induced polymers.  

PubMed

Optical experiments and theoretical considerations have been undertaken in order to understand the causes of the 'orientation effect' and the 'parabola effect', the artefacts impairing the desired light absorption measurement on radiochromic EBT3 films with flatbed scanners. EBT3 films exposed to doses up to 20.9 Gy were scanned with an Epson Expression 10000XL flatbed scanner in landscape and portrait orientation. The horizontally and vertically polarized light components of the scanner were determined, and another Epson Expression 10000XL flatbed scanner was disassembled to examine its optical components. The optical properties of exposed and unexposed EBT3 films were studied with incident polarized and unpolarized white light, and the transmitted red light was investigated for its polarization and scattering properties including the distribution of the scattering angles. Neutral density filters were studied for comparison. Guidance was sought from the theory of light scattering from rod-like macromolecular structures. The drastic dose-dependent variation of the transmitted total light current as function of the orientation of front and rear polarizers, interpreted by light scattering theory, shows that the radiation-induced polymerization of the monomers of EBT3 films produces light scattering oscillators preferably polarized at right angles with the coating direction of the film. The directional distribution of the scattered light is partly anisotropic, with a preferred scattering plane at right angles with the coating direction, indicating light scattering from stacks of coherently vibrating oscillators piled up along the monomer crystals. The polyester carrier film also participates in these effects. The 'orientation' and 'parabola' artefacts due to flatbed scanning of radiochromic films can be explained by the interaction of the polarization-dependent and anisotropic light scattering from exposed and unexposed EBT3 films with the quantitative difference between the scanner's horizontally and vertically polarized light supply and with the limited directional acceptance of the scanner's light recording system. PMID:24909235

Schoenfeld, Andreas A; Poppinga, Daniela; Harder, Dietrich; Doerner, Karl-Joachim; Poppe, Bjoern

2014-07-01

352

How effective can optical-CT 3D dosimetry be without refractive fluid matching?  

NASA Astrophysics Data System (ADS)

Achieving accurate optical CT 3D dosimetry without the use of viscous refractive index (RI) matching fluids would greatly increase convenience. Software has been developed to simulate optical CT 3D dosimetry for a range of scanning configurations including parallel-beam, point and converging light sources. For each configuration the efficacy of 3 refractive media were investigated: air, water, and a fluid closely matched to Presage (RI = 1.00, 1.33 and 1.49 respectively). The results revealed that the useable radius of the dosimeter (i.e. where data was within 2% of truth) reduced to 68% for water-matching, and 31% for dry-scanning in air. Point source incident ray geometry produced slightly more favourable results, although variation between the three geometries was relatively small. The required detector size however, increased by a factor six for dry-scanning, introducing cost penalties. For applications where dose information is not required in the periphery, some dry and low-viscous matching configurations may be feasible.

Rankine, L.; Oldham

2013-06-01

353

A survey of space radiation effects  

NASA Technical Reports Server (NTRS)

The effects of space radiation and its significance for space missions, as they increase in scope, duration, and complexity are discussed. Type of radiation hazard may depend on location or on special equipment used. It is emphasized that it is necessary to search for potential radiation problems in the design stage of a mission. Problem areas such as radiation damage to solar cells and the revolutionary advances are discussed. Radiation effect to electronics components other than solar cells, and several specialized areas such as radioactivity and luminescence are also examined.

Hill, C. W.

1980-01-01

354

Slope effects on shortwave radiation components and net radiation  

NASA Technical Reports Server (NTRS)

The main objective of the International Satellite Land Surface Climatology Project (ISLSCP) has been stated as 'the development of techniques that may be applied to satellite observations of the radiation reflected and emitted from the Earth to yield quantitative information concerning land surface climatological conditions.' The major field study, FIFE (the First ISLSCP Field Experiment), was conducted in 1978-89 to accomplish this objective. Four intensive field campaigns (IFC's) were carried out in 1987 and one in 1989. Factors contributing to observed reflected radiation from the FIFE site must be understood before the radiation observed by satellites can be used to quantify surface processes. Analysis since our last report has focused on slope effects on incoming and outgoing shortwave radiation and net radiation from data collected in 1989.

Walter-Shea, Elizabeth A.; Blad, Blaine L.; Hays, Cynthia J.; Mesarch, Mark A.

1992-01-01

355

A dosimetry study precisely outlining the heart substructure of left breast cancer patients using intensity-modulated radiation therapy.  

PubMed

The purpose of this study was to evaluate the feasibility of delineating the substructure of the heart by using 64-slice spiral CT coronary angiography (CTA) in breast cancer patients who underwent left breast-conserving surgery, and to compare the dosimetric differences between the targets and organs at risk in the prone and supine positions in intensity-modulated radiation therapy (IMRT) planning. From January to December 2011, ten patients who underwent left breast-conserving surgery were enrolled in this study. CTA was performed in both the supine and prone positions during the simulation, and conventional scanning without CTA was performed at the same time. Image registration was performed for paired image series using a commercially available planning system. In a conventional image series, the clinical target volume (CTV) of the whole breast, planning target volume (PTV), bilateral lungs (L-Lung, R-Lung), spinal cord, contralateral breast (R-Breast), and heart were delineated. In the CTA image series, the left ventricular (LV) and left anterior descending coronary arteries (LAD) and the planning risk volume (LAD-PRV) of the LAD (LAD with a 1 cm margin) were outlined. For each patient, two separate IMRT plans were developed for the supine and prone positions. A total of 20 plans were generated. The following indicators were compared: Dmean and D95 for the PTV; Dmean, V5, and V20 for the left lung; Dmean, V10, V20, V25, V30, and V40 for the heart and its substructures (LAD-PRV, LV); Dmean and V5 for the right lung; and Dmax and Dmean for the right breast. Using CTA to delineate the substructures of the heart is simple and straightforward. Plans for both the prone and supine positions reached the prescribed dose for the PTV without significant differences. Dose distributions were acceptable for both the prone and supine positions. However, the LAD-PRV, LV, heart, and L-Lung received smaller doses in the prone position plans than in the supine position plans. The Dmean values reduced by 445.83 cGy (p = 0.043), 575.00 cGy (p = 0.003), 402.00 cGy (p = 0.039), and 553.33 cGy (p = 0.004) in the LAD-PRV, LV, heart, and L-Lung. In addition, the V25 lessened 12.54% (p = 0.042) and 8.70% (p = 0.019) in the LV and heart, while the V20 was decreased 8.57% (p = 0.042), 15.21% (p = 0.026), 12.59% (p = 0.011), and 10.62% (p = 0.006) in the LAD-PRV, LV, heart, and L-Lung, respectively. Similarly, the V10 and V30 were reduced by 28.31% (p = 0.029) and 5.54% (p = 0.034) in the heart, while the V5 was cut back 27.86% (p = 0.031) in the L-Lung. For most Asian women with average-sized breasts after breast conserving treatment (BCT), prone positioning during IMRT radiation will reduce the dose to the ipsilateral lung, heart, and substructures of the heart, which may reduce the incidence of cardiovascular events after radiotherapy more than radiation therapy performed in a supine position. Using CTA to delineate the substructures of the heart is easy and intuitive. It is cost-effective and highly recommended for breast cancer IMRT. However, the dose-volume limits of the heart substructures remain to be determined. PMID:25207559

Fan, Ling-li; Luo, Yang-kun; Xu, Jing-hui; He, Ling; Wang, Jie; Du, Xiao-bo

2014-01-01

356

Multiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation Response Effects of Radiation Quality and HypoxiaEffects of Radiation Quality and Hypoxia  

E-print Network

Multiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation ResponseMultiscale Modeling of Radiation Response Effects of Radiation Quality and HypoxiaEffects of Radiation Quality and Hypoxia Robert D. Stewart, Ph.D.Robert D. Stewart, Ph

Stewart, Robert D.

357

Establishment of ANSI N13.11 X-ray radiation fields for personal dosimetry performance test by computation and experiment.  

PubMed Central

This paper describes establishment by computational and experimental methods of the American National Standard Institute (ANSI) N13.11 X-ray radiation fields by the Korea Atomic Energy Research Institute (KAERI). These fields were used in the standard irradiations of various personal dosimeters for the personal dosimetry performance test program performed by the Ministry of Science and Technology of Korea in the autumn of 1995. Theoretical X-ray spectra produced from two KAERI X-ray generators were estimated using a modified Kramers' theory with target attenuation and backscatter correction and their spectral distributions experimentally measured by a high-purity germanium semiconductor detector through proper corrections for measured pulse height distributions with photopeak efficiency, Compton fraction, and K-escape fraction. The average energies and conversion coefficients obtained from the computation and experimental methods, when compared with ANSI N13.11 and the recently published National Institute of Standards and Technology X-ray beams, appeared to be in good agreement--(+/-)3% between corresponding values--and thus, could be satisfactorily applied in the performance test of personal dosimeters. PMID:9467054

Kim, J L; Kim, B H; Chang, S Y; Lee, J K

1997-01-01

358

EPR dosimetry of teeth in past and future accidents: a prospective look at a retrospective method  

SciTech Connect

Electron paramagnetic resonance spectroscopy (EPR) of tooth enamel is a relatively new technique for retrospective dosimetry that in the past two years has seen increasing effort towards its development and evaluation. Efforts have centered on determining the accuracy which may be achieved with current measurement techniques as well as the minimum doses detectable. The study was focused on evaluating some factors which influence the accuracy of EPR dosimetry of enamel. Reported are studies on sample intercomparisions, instrumental considerations, and effects of dental x-rays, environmental sunlight and ultraviolet radiation.

Haskell, E.H.; Kenner, G.H.; Hayes, R.B. [Utah Univ., Salt Lake City, UT (United States). Center for Applied Dosimetry; Chumak, V.; Shalom, S. [All-Union Scientific Centre of Radiation Medicine, Kiev (Ukraine)

1996-01-01

359

Potential health effects of space radiation  

NASA Technical Reports Server (NTRS)

Crewmembers on missions to the Moon or Mars will be exposed to radiation belts, galactic cosmic rays, and possibly solar particle events. The potential health hazards due to these space radiations must be considered carefully to ensure the success of space exploration. Because there is no human radioepidemiological data for acute and late effects of high-LET (Linear-Energy-Transfer) radiation, the biological risks of energetic charged particles have to be estimated from experimental results on animals and cultured cells. Experimental data obtained to date indicate that charged particle radiation can be much more effective than photons in causing chromosome aberrations, cell killing, mutation, and tumor induction. The relative biological effectiveness (RBE) varies with biological endpoints and depends on the LET of heavy ions. Most lesions induced by low-LET radiation can be repaired in mammalian cells. Energetic heavy ions, however, can produce large complex DNA damages, which may lead to large deletions and are irreparable. For high-LET radiation, therefore, there are less or no dose rate effects. Physical shielding may not be effective in minimizing the biological effects on energetic heavy ions, since fragments of the primary particles can be effective in causing biological effects. At present the uncertainty of biological effects of heavy particles is still very large. With further understanding of the biological effects of space radiation, the career doses can be kept at acceptable levels so that the space radiation environment need not be a barrier to the exploitation of the promise of space.

Yang, Chui-Hsu; Craise, Laurie M.

1993-01-01

360

Criteria for personal dosimetry in mixed radiation fields in space. [analyzing trapped protons, tissue disintegration stars, and neutrons  

NASA Technical Reports Server (NTRS)

The complexity of direct reading and passive dosimeters for monitoring radiation is studied to strike the right balance of compromise to simplify the monitoring procedure. Trapped protons, tissue disintegration stars, and neutrons are analyzed.

Schaefer, H. J.

1974-01-01

361

Methods to Estimate Solar Radiation Dosimetry in Coral Reefs Using Remote Sensed, Modeled, and in Situ Data.  

EPA Science Inventory

Solar irradiance has been increasingly recognized as an important determinant of bleaching in coral reefs, but measurements of solar radiation exposure within coral reefs have been relatively limited. Solar irradiance and diffuse down welling attenuation coefficients (Kd, m-1) we...

362

The effects of variations in the density and composition of eye materials on ophthalmic brachytherapy dosimetry  

SciTech Connect

In ophthalmic brachytherapy dosimetry, it is common to consider the water phantom as human eye anatomy. However, for better clinical analysis, there is a need for the dose determination in different parts of the eye. In this work, a full human eye is simulated with MCNP-4C code by considering all parts of the eye, i.e., the lens, cornea, retina, choroid, sclera, anterior chamber, optic nerve, and bulk of the eye comprising vitreous body and tumor. The average dose in different parts of this full model of the human eye is determined and the results are compared with the dose calculated in water phantom. The central axes depth dose and the dose in whole of the tumor for these 2 simulated eye models are calculated as well, and the results are compared.

Asadi, Somayeh [Department of Physics, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Masoudi, Seyed Farhad, E-mail: masoudi@kntu.ac.ir [Department of Physics, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shahriari, Majid [Department of Radiation Application, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

2012-04-01

363

Radiation effects on optical fibers and amplifiers  

Microsoft Academic Search

The effects of gamma radiation on rare-earth doped optical fibers have been investigated over the range of 0.01 to 145 kilorads(Si) per hour to total doses exceeding 100 kilorads(Si). The effects of 3 to 4 MeV protons have also been investigated. The level of radiation induced damage has been found to be strongly dependent on radiation dose rate and fiber

Robert G. Ahrens; James J. Jaques; Michael J. LuValle; David J. DiGiovanni; Robert S. Windeler

2001-01-01

364

Practical neutron dosimetry at high energies  

SciTech Connect

Dosimetry at high energy particle accelerators is discussed with emphasis on physical measurements which define the radiation environment and provide an immutable basis for the derivation of any quantities subsequently required for risk evaluation. Results of inter-laboratory dosimetric comparisons are reviewed and it is concluded that a well-supported systematic program is needed which would make possible detailed evaluations and inter-comparisons of instruments and techniques in well characterized high energy radiation fields. High-energy dosimetry is so coupled with radiation transport that it is clear their study should proceed concurrently.

McCaslin, J.B.; Thomas, R.H.

1980-10-01

365

Radiation Effects in Nuclear Waste Materials  

SciTech Connect

The objective of this project is to develop a fundamental understanding of radiation effects in glasses and ceramics, as well as the influence of solid-state radiation effects on aqueous dissolution kinetics, which may impact the performance of nuclear waste forms and stabilized nuclear materials.

William j. Weber; Lumin Wang; Jonathan Icenhower

2004-07-09

366

Radiation effects of proton collisions in polymers  

NASA Astrophysics Data System (ADS)

Protons affect the polymers mainly through scission and crosslinking of macromolecule chains. Ionization processes at proton non-elastic scattering define these effects. One of the most important problems of radiation physics and chemistry of polymers is dependence of radiation effects in polymers on the kind of ionizing radiation or the problem of LET (Linear Energy Transfer) effect. Analyze of such dependence for protons and some other kinds of radiation is presented. A detailed examination of 100 MeV proton collisions in polyethyleneterephtalate (PETP, trade mark Mylar) on the base of the sample heat conductivity behavior revealed an important role of atom displacements resulting from elastic nuclear scattering. Similar results were obtained for polymethylmethacrylate irradiated by low energy protons. It is necessary also to take into account the establishing clusters of displaced atoms. Such damage of polymer molecules was not obtained for other examined types of radiation, in particular, for recoil nuclei at reactor neutron irradiation and for 60Co - gamma radiation.

Briskman, B. A.

2003-09-01

367

Effects Of Radiation On Insulators  

NASA Technical Reports Server (NTRS)

Report presents data on responses of electrically insulating thermosetting and thermoplastic polymers to radiation. Lowest-threshold-dose (LTD) levels and 25-percent-change levels presented for such properties as tensile strength and electrical resistivity. Data on radiation-induced outgassing also given.

Bouquet, Frank L.

1988-01-01

368

Dosimetry implant for treating restenosis and hyperplasia  

DOEpatents

The present invention discloses a method of selectively providing radiation dosimetry to a subject in need of such treatment. The radiation is applied by an implant comprising a body member and .sup.117mSn electroplated at selected locations of the body member, emitting conversion electrons absorbed immediately adjacent selected locations while not affecting surrounding tissue outside of the immediately adjacent area.

Srivastava, Suresh; Gonzales, Gilbert R; Howell, Roger W; Bolch, Wesley E; Adzic, Radoslav

2014-09-16

369

Fifth personnel dosimetry intercomparison study  

SciTech Connect

The fifth Personnel Dosimetry Intercomparison Study (PDIS) was conducted at the Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research (DOSAR) facility on March 20-22, 1979. This study is the latest PDIS in the continuing series started at the DOSAR facility in 1974. The PDIS is a three day study, typically in March, where personnel dosimeters are mailed to the DOSAR facility, exposed to a range of low-level neutron radiation doses (1 to 15 mSv or equivalently, 100 to 1500 mrem) and neutron-to-gamma ratios (1:1-10:1) using the Health Physics Research Reactor (HPRR) as the radiation source, and returned to the participants for evaluation. This report is a summary and analysis of the results reported by the various participants. The participants are able to intercompare their results with those of others who made dose measurements under identical experimental conditions.

Sims, C.S.

1980-02-01

370

Physics of intense, high energy radiation effects.  

SciTech Connect

This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the continuum calculations and the experiments.

Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart

2011-02-01

371

Protective effects in radiation modification of elastomers  

NASA Astrophysics Data System (ADS)

Saturated character of ethylene/octene thermoplastic elastomers demands an application of nonconventional methods of crosslinking connections between chains of molecules. These are organic peroxides, usually in the presence of coagents or an application of ionizing radiation. Several approaches (radiation, peroxide, peroxide/plus radiation and radiation/plus peroxide) were applied in crosslinking of elastomere Engage 8200. Attention was directed to the protection effects by aromatic peroxides and by photo- and thermostabilizers on radiolysis of elastomers. Role of dose of radiation, dose rate of radiation as well as the role of composition of elastomere on the radiation yield of hydrogen and absorbtion of oxygen was investigated. DRS method was used to follow postirradiation degradation. Influence of crosslinking methods on properties of elastomers is described. Results were interpreted from the point of view of protective actions of aromatic compounds.

G?uszewski, Wojciech; Zagórski, Zbigniew P.; Rajkiewicz, Maria

2014-12-01

372

Radiation effects in solar cells  

NASA Astrophysics Data System (ADS)

Two types of space solar cells, silicon single-junction and InGaP/GaAs/Ge triple-junction (3J) solar cells, have been primarily adopted for spacecraft. The conversion efficiencies of the solar cells under AM0, 1 sun condition are ~17% for silicon and ~30% for 3J cells. Radiation degradation occurs in space due to high-energy electrons and protons existing in space environment. The degradation is caused by radiation induced crystal defects which act as minority-carrier recombination centers and majority-carrier trap centers. The 3J cells are superior radiation resistant to the silicon cells, and this is mainly because the InGaP top-subcell has property of very high radiation resistance.

Imaizumi, Mitsuru; Ohshima, Takeshi

2013-05-01

373

Radiation effects in optoelectronic devices. [Review  

SciTech Connect

Purpose of this report is to provide not only a summary of radiation damage studies at Sandia National Laboratories, but also of those in the literature on the components of optoelectronic systems: light emitting diodes (LEDs), laser diodes, photodetectors, optical fibers, and optical isolators. This review of radiation damage in optoelectronic components is structured according to device type. In each section, a brief discussion of those device properties relevant to radiation effects is given.

Barnes, C.E.; Wiczer, J.J.

1984-05-01

374

Radiation damage effects on solid state detectors  

NASA Technical Reports Server (NTRS)

Totally depleted silicon diodes are discussed which are used as nuclear particle detectors in investigations of galactic and solar cosmic radiation and trapped radiation. A study of radiation and chemical effects on the diodes was conducted. Work on electron and proton irradiation of surface barrier detectors with thicknesses up to 1 mm was completed, and work on lithium-drifted silicon devices with thicknesses of several millimeters was begun.

Trainor, J. H.

1972-01-01

375

Radiation friction versus ponderomotive effect  

NASA Astrophysics Data System (ADS)

The concept of ponderomotive potential is upgraded to a regime in which radiation friction becomes dominant. The radiation friction manifests itself in long-term capturing of the particles released at the focus and impenetrability of the focus from the exterior. We apply time scale separation to the Landau-Lifshitz equation splitting the particle motion into quivering and slow drift of a guiding center. The drift equation is deduced by averaging over fast motion.

Fedotov, A. M.; Elkina, N. V.; Gelfer, E. G.; Narozhny, N. B.; Ruhl, H.

2014-11-01

376

Radiation effects in the lung  

SciTech Connect

This article outlines the principles of radiobiology that can explain the time of onset, duration, and severity of the complex reactions of the lung to ionizing radiation. These reactions have been assayed biochemically, cell kinetically, physiologically, and pathologically. Clinical and experimental data are used to describe the acute and late reactions of the lung to both external and internal radiation including pneumonitis, fibrosis and carcinogenesis. Acute radiation pneumonitis, which can be fatal, develops in both humans and animals within 6 months of exposure to doses greater than or equal to 8 Gy of low LET radiation. It is divisible into a latent period lasting up to 4 weeks; an exudative phase (3-8 weeks) and with an acute pneumonitic phase between 2 and 6 months. There is much evidence to suggest that pneumonitis is an epithelial reaction and some evidence to suggest that this early damage may not be predictive of late fibrosis. However, despite detailed work on collagen metabolism, the pathogenesis of radiation fibrosis remains unknown. The data on radiation-induced pulmonary cancer, both in man and experimental animals from both external and internal irradiation following the inhalation of both soluble and insoluble alpha and beta emitting radionuclides are reviewed. 312 references. (Abstract Truncated)

Coggle, J.E.; Lambert, B.E.; Moores, S.R.

1986-12-01

377

2.2.1 Ionizing Radiation  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.2.1 Ionizing Radiation' of the Section '2.2 Kinds of Radiation' of the Chapter '2 Radiation and Biological Effects' with the contents:

Kasch, K.-U.

378

Breast dosimetry.  

PubMed

The estimation of the absorbed dose to the breast is an important part of the quality control of the mammographic examination. Knowledge of breast dose is essential for the design and performance assessment of mammographic imaging systems. This review gives a historical introduction to the measurement of breast dose. The mean glandular dose (MGD) is introduced as an appropriate measure of breast dose. MGD can be estimated from measurements of the incident air kerma at the surface of the breast and the application of an appropriate conversion factor. Methods of calculating and measuring this conversion factor are described and the results discussed. The incident air kerma itself may be measured for patients or for a test phantom simulating the breast. In each case the dose may be determined using TLD measurements, or known exposure parameters and measurements of tube output. The methodology appropriate to each case is considered and the results from sample surveys of breast dose are presented. Finally the various national protocols for breast dosimetry are compared. PMID:10028637

Dance, D R; Skinner, C L; Carlsson, G A

1999-01-01

379

Organ-specific dosimetry in spinal radiography: an analysis of genetic and somatic effects  

SciTech Connect

Radiation doses absorbed by the uterus, ovary, testicle and active bone marrow are computed for cervical, thoracic, lumbar, full spine and chest series performed under typical office conditions. Assuming a nonthreshold, linear relationship between dose and radiogenic effect, the computed tissue-specific doses are used to estimate the probability that each X-ray series might enhance the statistical probability of occurrence of an adult leukemia fatality of the irradiated patient; a childhood leukemia, mental retardation or cancer fatality as a result of fetal irradiation; or a variety of sex cell chromosomal aberrations in irradiated patients. It is concluded that the greatest hazard to active bone marrow, the uterus and the gonads is posed by lumbar and full spine radiography and that the need to adequately justify such exposure is mandatory; furthermore, in these series, irradiation of the ovary is 10 times as great as that of the testicle. Lumbar radiographic examinations can be made significantly safer by the elimination of the lumbosacral spot view.

Fickel, T.E.

1988-02-01

380

Intensity-modulated radiation therapy (IMRT) dosimetry of the head and neck: A comparison of treatment plans using linear accelerator-based IMRT and helical tomotherapy  

SciTech Connect

Purpose: To date, most intensity-modulated radiation therapy (IMRT) delivery has occurred using linear accelerators (linacs), although helical tomotherapy has become commercially available. To quantify the dosimetric difference, we compared linac-based and helical tomotherapy-based treatment plans for IMRT of the oropharynx. Methods and Materials: We compared the dosimetry findings of 10 patients who had oropharyngeal carcinoma. Five patients each had cancers in the base of the tongue and tonsil. Each plan was independently optimized using either the CORVUS planning system (Nomos Corporation, Sewickly, PA), commissioned for a Varian 2300 CD linear accelerator (Varian Medical Systems, Palo Alto, CA) with 1-cm multileaf collimator leaves, or helical tomotherapy. The resulting treatment plans were evaluated by comparing the dose-volume histograms, equivalent uniform dose (EUD), dose uniformity, and normal tissue complication probabilities. Results: Helical tomotherapy plans showed improvement of critical structure avoidance and target dose uniformity for all patients. The average equivalent uniform dose reduction for organs at risk (OARs) surrounding the base of tongue and the tonsil were 17.4% and 27.14% respectively. An 80% reduction in normal tissue complication probabilities for the parotid glands was observed in the tomotherapy plans relative to the linac-based plans. The standard deviation of the planning target volume dose was reduced by 71%. In our clinic, we use the combined dose-volume histograms for each class of plans as a reference goal for helical tomotherapy treatment planning optimization. Conclusions: Helical tomotherapy provides improved dose homogeneity and normal structure dose compared with linac-based IMRT in the treatment of oropharyngeal carcinoma resulting in a reduced risk for complications from focal hotspots within the planning target volume and for the adjacent parotid glands.

Sheng Ke [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States)]. E-mail: ks2mc@virginia.edu; Molloy, Janelle A. [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States); Department of Radiation Oncology, Mayo Clinic, Rochester, MN (United States); Read, Paul W. [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States)

2006-07-01

381

Polymer gel dosimetry  

NASA Astrophysics Data System (ADS)

Polymer gels are chemical dosimeters based on dose dependent radiation-induced polymerization and cross-linking of monomers in an irradiated volume. The changes are spatially localized in the volume by incorporating the initial monomers in an aqueous gel matrix in the dosimeter and can be probed by various imaging techniques such as magnetic resonance imaging (MRI), x-ray computed tomography (CT), and optical CT. As they are chemical dosimeters, polymer gels are sensitive to preparation conditions. The three dimensional dose readout is sensitive to the imaging modality and also to the technical conditions in use during specific scans. This brief article is intended to present an introduction to these points which need to be taken into account as one attempts to establish this dosimetry in the clinic.

Schreiner, L. J.; Olding, T.; McAuley, K. B.

2010-11-01

382

Effects of ionizing radiation on hippocampal excitability  

SciTech Connect

Ionizing radiation causes striking changes in hippocampal activity in vivo. Changes in neuronal firing patterns and spiking activity in electroencephalographic recordings appear at doses as low as 4 Gy. Accompanying exposure to ionizing radiation is a breakdown in blood brain barrier and a decrease in cerebral blood flow. In an effort to define the mechanisms of radiation damage to neuronal excitability, without these complicating factors, the effects of radiation on neuronal activity in hippocampal slices were investigated. Damage is likely to result from generation of free radicals. Since peroxide mixed with iron produces hydroxyl free radicals through the Fenton reaction, peroxidative damage was evaluated on hippocampal slices for comparison.

Pellmar, T.C.; Tolliver, J.M.

1986-01-01

383

Flare loop radiative hydrodynamics. III - Nonlocal radiative transfer effects  

NASA Technical Reports Server (NTRS)

The study has three goals. The first is to demonstrate that processes exist whose intrinsic nonlocal nature cannot be represented by local approximations. The second is to elucidate the physical nature and origins of these nonlocal processes. The third is to suggest that the methods and results described here may prove useful in constructing semiempirical models of the chromosphere by means more efficient than trial and error. Matrices are computed that describe the effect of a temperature perturbation at an arbitrary point in the loop on density, hydrogen ionized fraction, total radiative loss rate, and radiative loss rate of selected hydrogen lines and continua at all other points. It is found that the dominant nonlocal radiative transfer effects can be separated into flux divergence coefficient effects and upper level population effects. The former are most important when the perturbation takes place in a region of significant opacity. Upper level population effects arise in both optically thick and thin regions in response to nonlocal density, ionization, and interlocking effects.

Canfield, R. C.; Fisher, G. H.; Mcclymont, A. N.

1983-01-01

384

The Effects of Ionizing Radiation on Mammalian Cells.  

ERIC Educational Resources Information Center

Discusses the effects of radiation on dividing cells and factors influencing these effects; also briefly reviews the radical mechanism for radiation damage. Emphasizes the importance of oxygen in radiation effects. (CS)

Biaglow, John E.

1981-01-01

385

Historical Evaluation of Film Badge Dosimetry Y-12 Plant: Part 2–Neutron Radiation ORAUT-OTIB-0045  

SciTech Connect

A summary of the major neutron sources involved in radiation exposures to Y-12 workers is presented in this TIB. Graphical methods are used to evaluate available neutron dose data from quarterly exposures to Y-12 workers and to determine how the data could be used to derive neutron-to-gamma dose ratios for dose reconstruction purposes. This TIB provides estimates of neutron-to-gamma dose ratios for specific departments and a default value for the neutron-to-gamma dose ratio based on the pooled neutron dose data for all Y-12 departments.

Kerr GD, Frome EL, Watkins JP, Tankersley WG

2009-12-14

386

Quenching Effect, Signal to Noise, Contrast to Noise Ratios on Scintillator Screens for Proton Beam Dosimetry System  

NASA Astrophysics Data System (ADS)

There has been dosimetry using scintillator screen for proton quality assurance recently. To develop a proton beam dosimetry system using scintillator, we evaluated the dosimetric properties and imaging quality for three kinds of scintillator screens. Proton beam ranges of 6, 9, and 12 g/cm2 were determined in a water phantom using an ion chamber. Beam current was optimized about each scintillator screen at proton beam ranges of 6, 9, and 12 g/cm2. Dose rate was in beam condition of proton treatment. For comparison of the dosimetric properties, the quenching correction factors and standard deviations for the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) were obtained using the relation between the light yield (scintillator-relative output) and the dose distribution (diode-relative output). The image qualities for the scintillator screens were compared, using the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR), in consideration of the physical properties of the scintillator materials. After correction of the quenching effect, the correction factor for scintillator screen Gd2O2S:Tb was the lowest, at 0.004 g/(cm2 MeV). The standard deviations of the difference between the yields measured by the scintillator screens and the diode detector averaged 1, 1.3, and 1.3, respectively, at all of the ranges from origin to the peak position. The dosimetric properties of scintillator screens were no large difference. The SNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 28.67, 40.18, and 24.56, respectively, at all ranges. The CNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 0.44, 0.33, and 0.42, respectively, at all ranges. The highest SNR and the lowest CNR of scintillator screen Gd2O2S:Tb were more excellent than those of the other scintillator screens. We evaluated the dosimetric properties in terms of the quenching-effect correction factors, standard deviations image qualities in terms of SNR and CNR about scintillator screens. The correction factor and standard deviation for scintillator screens made no large difference. Scintillator screen Gd2O2S:Tb had the highest value of SNR and the lowest value of CNR, and accordingly was considered to be best in proton beam imaging quality.

Kim, Seonkyu; Byeong Lee, Se; Yoo, Seung Hoon; Cho, Sungkoo; Kim, Dong Wook; Shin, Dongho; Park, Sung Yong; Kim, Chan Hyeong; Lee, Sang Hoon

2012-04-01

387

A combined approach to the simulation of ionizing radiation effects in silicon devices  

Microsoft Academic Search

Silicon devices (both pixels and microstrips) have been widely used in the past years in High Energy Physics experiments and also in other applications involving the detection of ionizing radiation such as medical imaging and dosimetry. The simulation of the silicon devices response to ionizing radiation is an important step needed to understand the performances in terms of signal, noise,

T. Ozdemir; S. Meroli; E. Pilicer

2011-01-01

388

Radiation effect on rocket engine performance  

NASA Technical Reports Server (NTRS)

Critical problem areas involving the effect of radiation on the combustion of bipropellants are addressed by formulating a universal scaling law in combination with a radiation-enhanced vaporization combustion model. Numerical algorithms are developed and data pertaining to the Variable Thrust Engine (VTE) and the Space Shuttle Main Engine (SSME) are used to conduct parametric sensitivity studies to predict the principal intercoupling effects of radiation. The analysis reveals that low-enthalpy engines, such as the VTE, are vulnerable to a substantial performance setback due to radiative loss, whereas the performance of high-enthalpy engines such as the SSME are hardly affected over a broad range of engine operation. Combustion enhancement by radiative heating of the propellant has a significant impact on propellants with high absorptivity.

Chiu, Huei-Huang; Kross, K. W.; Krebsbach, A. N.

1990-01-01

389

RADIATION EFFECTS IN NUCLEAR WASTE MATERIALS  

EPA Science Inventory

The objective of this multidisciplinary, multi-institutional research effort is to develop a fundamental understanding at the atomic, microscopic, and macroscopic levels of radiation effects in glass and ceramics that provides the underpinning science and models for evaluation an...

390

Assurance Against Radiation Effects on Electronics  

NASA Technical Reports Server (NTRS)

Contents include the following: The Space Radiation Environment. The Effects on Electronics. The Environment in Action. NASA Approaches to Commercial Electronics: the mission mix, flight projects, and proactive research. Final Thoughts: atomic interactions, direct ionization, interaction with nucleus.

LaBel, Kenneth A.

2004-01-01

391

Annual Conference on Nuclear and Space Radiation Effects, 18th, University of Washington, Seattle, WA, July 21-24, 1981, Proceedings  

NASA Technical Reports Server (NTRS)

Single event upset phenomena are discussed, taking into account cosmic ray induced errors in IIL microprocessors and logic devices, single event upsets in NMOS microprocessors, a prediction model for bipolar RAMs in a high energy ion/proton environment, the search for neutron-induced hard errors in VLSI structures, soft errors due to protons in the radiation belt, and the use of an ion microbeam to study single event upsets in microcircuits. Basic mechanisms in materials and devices are examined, giving attention to gamma induced noise in CCD's, the annealing of MOS capacitors, an analysis of photobleaching techniques for the radiation hardening of fiber optic data links, a hardened field insulator, the simulation of radiation damage in solids, and the manufacturing of radiation resistant optical fibers. Energy deposition and dosimetry is considered along with SGEMP/IEMP, radiation effects in devices, space radiation effects and spacecraft charging, EMP/SREMP, and aspects of fabrication, testing, and hardness assurance.

Tasca, D. M.

1981-01-01

392

Dosimetry of radium-223 and progeny  

SciTech Connect

Radium-223 is a short-lived (11.4 d) alpha emitter with potential applications in radioimmunotherapy of cancer. Radium-223 can be complexed and linked to protein delivery molecules for specific tumor-cell targeting. It decays through a cascade of short-lived alpha- and beta-emitting daughters with emission of about 28 MeV of energy through complete decay. The first three alpha particles are essentially instantaneous. Photons associated with Ra-223 and progeny provide the means for tumor and normal-organ imaging and dosimetry. Two beta particles provide additional therapeutic value. Radium-223 may be produced economically and in sufficient amounts for widescale application. Many aspects of the chemistry of carrier-free isotope preparation, complexation, and linkage to the antibody have been developed and are being tested. The radiation dosimetry of a Ra-223-labeled antibody shows favorable tumor to normal tissue dose ratios for therapy. The 11.4-d half-life of Ra-223 allows sufficient time for immunoconjugate preparation, administration, and tumor localization by carrier antibodies before significant radiological decay takes place. If 0.01 percent of a 37 MBq (1 mCi) injection deposits in a one gram tumor mass, and if the activity is retained with a typical effective half-time (75 h), the absorbed dose will be 163 mGy MBq{sup {minus}1} (600 rad mCi{sup {minus}1}) administered. 49 refs., 5 figs., 2 tabs.

Fisher, D.R. [Pacific Northwest National Lab., Richland, WA (United States); Sgouros, G. [Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

1999-01-01

393

Ninth Annual Warren K. Sinclair Keynote Address: effects of childhood radiation exposure: an issue from computed tomography scans to Fukushima.  

PubMed

The acute and chronic effects of radiation on children have been and will continue to be of great social, public health, scientific, and clinical importance. The focus of interest on ionizing radiation and children has been clear for over half a century and ranges from the effects of fallout from nuclear weapons testing to exposures from accidents, natural radiation, and medical procedures. There is a loosely stated notion that "children are three to five times more sensitive to radiation than adults." Is this really true? In fact, children are at greater risk for some health effects, but not all. For a few sequelae, children may be more resistant than adults. Which are those effects? How and why do they occur? While there are clear instances of increased risk of some radiation-induced tumors in children compared to adults, there are other tumor types in which there appears to be little or no difference in risk by age at exposure and some in which published models that assume the same relative increase in risks for child compared to adult exposures apply to nearly all tumor types are not supported by the scientific data. The United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR) has a task group producing a comprehensive report on the subject. The factors to be considered include relevant radiation sources; developmental anatomy and physiology; dosimetry; and stochastic, deterministic, and hereditary effects. PMID:24077040

Mettler, Fred A; Constine, Louis S; Nosske, Dietmar; Shore, Roy E

2013-11-01

394