Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams.

PubMed

Poppinga, D; Halbur, J; Lemmer, S; Delfs, B; Harder, D; Looe, H K; Poppe, B

2017-09-05

The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm -3 ) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm  ×  10 cm field size agreed with the results of ionization chamber measurements within  ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.

Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams

NASA Astrophysics Data System (ADS)

Poppinga, D.; Halbur, J.; Lemmer, S.; Delfs, B.; Harder, D.; Looe, H. K.; Poppe, B.

2017-09-01

The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm-3) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm  ×  10 cm field size agreed with the results of ionization chamber measurements within  ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.

Membrane Signaling Induced by High Doses of Ionizing Radiation in the Endothelial Compartment. Relevance in Radiation Toxicity

PubMed Central

Corre, Isabelle; Guillonneau, Maëva; Paris, François

2013-01-01

Tumor areas can now be very precisely delimited thanks to technical progress in imaging and ballistics. This has also led to the development of novel radiotherapy protocols, delivering higher doses of ionizing radiation directly to cancer cells. Despite this, radiation toxicity in healthy tissue remains a major issue, particularly with dose-escalation in these new protocols. Acute and late tissue damage following irradiation have both been linked to the endothelium irrigating normal tissues. The molecular mechanisms involved in the endothelial response to high doses of radiation are associated with signaling from the plasma membrane, mainly via the acid sphingomyelinase/ceramide pathway. This review describes this signaling pathway and discusses the relevance of targeting endothelial signaling to protect healthy tissues from the deleterious effects of high doses of radiation. PMID:24252908

Modulation of inflammation by low and high doses of ionizing radiation: Implications for benign and malign diseases.

PubMed

Frey, Benjamin; Hehlgans, Stephanie; Rödel, Franz; Gaipl, Udo S

2015-11-28

Inflammation is a homeostatic mechanism aiming to maintain tissue integrity. The underlying immunological mechanisms and the interrelationship between ionizing radiation and inflammation are complex and multifactorial on cellular and chemical levels. On the one hand, radiation with single doses exceeding 1 Gy might initiate inflammatory reactions and thereby impact on tumor development. On the other hand, radiation is capable of attenuating an established inflammatory process, which is clinically used for the treatment of inflammatory and degenerative diseases with low-dose radiotherapy (single dose <1 Gy). At higher doses, ionizing radiation, especially in combination with additional immune stimulation, fosters the induction of immunogenic forms of tumor cell death and shifts the tumor microenvironment as well as the infiltration of immune cells from an anti- to a pro-inflammatory state. Distinct tumor infiltrating immune cells predict the response to radiochemotherapy in a multitude of tumor entities. While a high tumor infiltration of these adaptive immune cells mostly predicts a favorable disease outcome, a high infiltration of tumor-associated macrophages predicts an unfavorable response. Pro-inflammatory events should dominate over anti-inflammatory ones in this scenario. This review focuses on how ionizing radiation modulates inflammatory events in benign inflammatory and in malign diseases. A special focus is set on the role of tumor infiltrating lymphocytes and macrophages as biomarkers to predict treatment response and anti-tumor immunity and on mechanisms implicated in the anti-inflammatory effects of low-dose radiation therapy. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Identifying and managing the risks of medical ionizing radiation in endourology.

PubMed

Yecies, Todd; Averch, Timothy D; Semins, Michelle J

2018-02-01

The risks of exposure to medical ionizing radiation is of increasing concern both among medical professionals and the general public. Patients with nephrolithiasis are exposed to high levels of ionizing radiation through both diagnostic and therapeutic modalities. Endourologists who perform a high-volume of fluoroscopy guided procedures are also exposed to significant quantities of ionizing radiation. The combination of judicious use of radiation-based imaging modalities, application of new imaging techniques such as ultra-low dose computed tomography (CT) scan, and modifying use of current technology such as increasing ultrasound and pulsed fluoroscopy utilization offers the possibility of significantly reducing radiation exposure. We present a review of the literature regarding the risks of medical ionizing radiation to patients and surgeons as it pertains to the field of endourology and interventions that can be performed to limit this exposure. A review of the current state of the literature was performed using MEDLINE and PubMed. Interventions designed to limit patient and surgeon radiation exposure were identified and analyzed. Summaries of the data were compiled and synthesized in the body of the text. While no level 1 evidence exists demonstrating the risk of secondary malignancy with radiation exposure, the preponderance of evidence suggests a dose and age dependent increase in malignancy risk from ionizing radiation. Patients with nephrolithiasis were exposed to an average effective dose of 37mSv over a 2 year period. Multiple evidence-based interventions to limit patient and surgeon radiation exposure and associated risk were identified. Current evidence suggest an age and dose dependent risk of secondary malignancy from ionizing radiation. Urologists must act in accordance with ALARA principles to safely manage nephrolithiasis while minimizing radiation exposure.

Terrestrial Sources of X-Ray Radiation and Their Effects on NASA Flight Hardware

NASA Technical Reports Server (NTRS)

Kniffin, Scott

2016-01-01

X-rays are an energetic and penetrating form of ionizing electromagnetic radiation, which can degrade NASA flight hardware. The main concern posed by such radiation is degradation of active electronic devices and, in some cases, diodes. Non-electronic components are only damaged at doses that far exceed the point where any electronic device would be destroyed. For the purposes of this document, flight hardware can be taken to mean an entire instrument, the flight electronics within the instrument or the individual microelectronic devices in the flight electronics. This document will discuss and describe the ways in which NASA flight hardware might be exposed to x-rays, what is and isn't a concern, and how to tell the difference. First, we must understand what components in flight hardware may be vulnerable to degradation or failure as a result of being exposed to ionizing radiation, such as x-rays. As stated above, bulk materials (structural metals, plastics, etc.) are generally only affected by ionizing radiation at very high dose levels. Likewise, passive electronic components (e.g. resistors, capacitors, most diodes) are strongly resistant to exposure to x-rays, except at very high doses. The main concerns arise when active components, that is, components like discrete transistors and microelectronic devices, are exposed to ionizing radiation. Active components are designed to respond to minute changes in currents and voltages in the circuit. As such, it is not surprising that exposure to ionizing radiation, which creates ionized and therefore electrically active particles, may degrade the way the hardware performs. For the most part, the mechanism for this degradation is trapping of the charges generated by ionizing radiation by defects in dielectric materials in the hardware. As such, the degree of damage is a function of both the quantity of ionizing radiation exposure and the physical characteristics of the hardware itself. The metric that describes the level of exposure to ionizing radiation is total ionizing dose (TID). The unit of TID is the rad, which is defined as 100 ergs absorbed per gram of material. Dose can be expressed in other units, for example grays (gy), where 1 gy = 100 rads. The actual fluence of radiation needed to deliver a rad depends on the absorbing material, so units of dose are usually stated in reference to the material of interest. That is, for microelectronic devices, the unit of dose is generally rad (Si) or rad (SiO2). However, the definition of absorbed dose in this fashion has the advantage that the type of radiation causing the ionization can be normalized so that a realistic and adequate comparison can be made. The sensitivity of microelectronic parts to TID varies over many orders of magnitude. (Note: Doses to humans are typically expressed in rems-or roentgen-equivalent-man-which measures tissue damage, and depends on the type of radiation, as well as the dose in rads.) Thus far, the "softest" parts tested at NASA showed damage at 500 rads (Si), while parts that are radiation-hardened by design can remain functional to doses on the order of 107 rads (Si). This broad range of sensitivity highlights one of the most important considerations when considering the effects of radiation on electronic parts: In order to determine whether a radiation exposure is a concern for a particular part, one must understand the technologies used in the part and their vulnerabilities to TID damage. A NASA radiation expert should be consulted to obtain such information.

Commentary: Ethical Issues of Current Health-Protection Policies on Low-Dose Ionizing Radiation

PubMed Central

Socol, Yehoshua; Dobrzyński, Ludwik; Doss, Mohan; Feinendegen, Ludwig E.; Janiak, Marek K.; Miller, Mark L.; Sanders, Charles L.; Scott, Bobby R.; Ulsh, Brant; Vaiserman, Alexander

2014-01-01

The linear no-threshold (LNT) model of ionizing-radiation-induced cancer is based on the assumption that every radiation dose increment constitutes increased cancer risk for humans. The risk is hypothesized to increase linearly as the total dose increases. While this model is the basis for radiation safety regulations, its scientific validity has been questioned and debated for many decades. The recent memorandum of the International Commission on Radiological Protection admits that the LNT-model predictions at low doses are “speculative, unproven, undetectable and ‘phantom’.” Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of sparsely-ionizing or sparsely-ionizing plus highly-ionizing radiation may be beneficial to human health (hormesis/adaptive response). The present LNT-model-based regulations impose excessive costs on the society. For example, the median-cost medical program is 5000 times more cost-efficient in saving lives than controlling radiation emissions. There are also lives lost: e.g., following Fukushima accident, more than 1000 disaster-related yet non-radiogenic premature deaths were officially registered among the population evacuated due to radiation concerns. Additional negative impacts of LNT-model-inspired radiophobia include: refusal of some patients to undergo potentially life-saving medical imaging; discouragement of the study of low-dose radiation therapies; motivation for radiological terrorism and promotion of nuclear proliferation. PMID:24910586

Low-Dose, Ionizing Radiation and Age-Related Changes in Skeletal Microarchitecture

DOE PAGES

Alwood, Joshua S.; Kumar, Akhilesh; Tran, Luan H.; ...

2012-01-01

Osteoporosis can profoundly affect the aged as a consequence of progressive bone loss; high-dose ionizing radiation can cause similar changes, although less is known about lower doses (≤100 cGy). We hypothesized that exposure to relatively low doses of gamma radiation accelerates structural changes characteristic of skeletal aging. Mice (C57BL/6J-10 wk old, male) were irradiated (total body; 0-sham, 1, 10 or 100 cGy 137 Cs) and tissues harvested on the day of irradiation, 1 or 4 months later. Microcomputed tomography was used to quantify microarchitecture of high turnover, cancellous bone. Irradiation at 100 cGy caused transient microarchitectural changes over one month that were only evident atmore » longer times in controls (4 months). Ex vivo bone cell differentiation from the marrow was unaffected by gamma radiation. In conclusion, acute ionizing gamma irradiation at 100 cGy (but not at 1 cGy or 10 cGy) exacerbated microarchitectural changes normally found during progressive, postpubertal aging prior to the onset of age-related osteoporosis.« less

Low-Dose, Ionizing Radiation and Age-Related Changes in Skeletal Microarchitecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alwood, Joshua S.; Kumar, Akhilesh; Tran, Luan H.

Osteoporosis can profoundly affect the aged as a consequence of progressive bone loss; high-dose ionizing radiation can cause similar changes, although less is known about lower doses (≤100 cGy). We hypothesized that exposure to relatively low doses of gamma radiation accelerates structural changes characteristic of skeletal aging. Mice (C57BL/6J-10 wk old, male) were irradiated (total body; 0-sham, 1, 10 or 100 cGy 137 Cs) and tissues harvested on the day of irradiation, 1 or 4 months later. Microcomputed tomography was used to quantify microarchitecture of high turnover, cancellous bone. Irradiation at 100 cGy caused transient microarchitectural changes over one month that were only evident atmore » longer times in controls (4 months). Ex vivo bone cell differentiation from the marrow was unaffected by gamma radiation. In conclusion, acute ionizing gamma irradiation at 100 cGy (but not at 1 cGy or 10 cGy) exacerbated microarchitectural changes normally found during progressive, postpubertal aging prior to the onset of age-related osteoporosis.« less

A 0.18 micrometer CMOS Thermopile Readout ASIC Immune to 50 MRAD Total Ionizing Dose (SI) and Single Event Latchup to 174MeV-cm(exp 2)/mg

NASA Technical Reports Server (NTRS)

Quilligan, Gerard T.; Aslam, Shahid; Lakew, Brook; DuMonthier, Jeffery J.; Katz, Richard B.; Kleyner, Igor

2014-01-01

Radiation hardened by design (RHBD) techniques allow commercial CMOS circuits to operate in high total ionizing dose and particle fluence environments. Our radiation hard multi-channel digitizer (MCD) ASIC (Figure 1) is a versatile analog system on a chip (SoC) fabricated in 180nm CMOS. It provides 18 chopper stabilized amplifier channels, a 16- bit sigma-delta analog-digital converter (SDADC) and an on-chip controller. The MCD was evaluated at Goddard Space Flight Center and Texas A&M University's radiation effects facilities and found to be immune to single event latchup (SEL) and total ionizing dose (TID) at 174 MeV-cm(exp 2)/mg and 50 Mrad (Si) respectively.

Dosimetry for electron Intra-Operative RadioTherapy: Comparison of output factors obtained through alanine/EPR pellets, ionization chamber and Monte Carlo-GEANT4 simulations for IORT mobile dedicate accelerator

NASA Astrophysics Data System (ADS)

Marrale, Maurizio; Longo, Anna; Russo, Giorgio; Casarino, Carlo; Candiano, Giuliana; Gallo, Salvatore; Carlino, Antonio; Brai, Maria

2015-09-01

In this work a comparison between the response of alanine and Markus ionization chamber was carried out for measurements of the output factors (OF) of electron beams produced by a linear accelerator used for Intra-Operative Radiation Therapy (IORT). Output factors (OF) for conventional high-energy electron beams are normally measured using ionization chamber according to international dosimetry protocols. However, the electron beams used in IORT have characteristics of dose per pulse, energy spectrum and angular distribution quite different from beams usually used in external radiotherapy, so the direct application of international dosimetry protocols may introduce additional uncertainties in dosimetric determinations. The high dose per pulse could lead to an inaccuracy in dose measurements with ionization chamber, due to overestimation of ks recombination factor. Furthermore, the electron fields obtained with IORT-dedicated applicators have a wider energy spectrum and a wider angular distribution than the conventional fields, due to the presence of electrons scattered by the applicator's wall. For this reason, a dosimetry system should be characterized by a minimum dependence from the beam energy and from angle of incidence of electrons. This become particularly critical for small and bevelled applicators. All of these reasons lead to investigate the use of detectors different from the ionization chamber for measuring the OFs. Furthermore, the complete characterization of the radiation field could be accomplished also by the use of Monte Carlo simulations which allows to obtain detailed information on dose distributions. In this work we compare the output factors obtained by means of alanine dosimeters and Markus ionization chamber. The comparison is completed by the Monte Carlo calculations of OFs determined through the use of the Geant4 application "iort _ therapy" . The results are characterized by a good agreement of response of alanine pellets and Markus ionization chamber and Monte Carlo results (within about 3%) for both flat and bevelled applicators.

LiF TLD-100 as a Dosimeter in High Energy Proton Beam Therapy-Can It Yield Accurate Results?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zullo, John R.; Kudchadker, Rajat J.; Zhu, X. Ronald

In the region of high-dose gradients at the end of the proton range, the stopping power ratio of the protons undergoes significant changes, allowing for a broad spectrum of proton energies to be deposited within a relatively small volume. Because of the potential linear energy transfer dependence of LiF TLD-100 (thermolumescent dosimeter), dose measurements made in the distal fall-off region of a proton beam may be less accurate than those made in regions of low-dose gradients. The purpose of this study is to determine the accuracy and precision of dose measured using TLD-100 for a pristine Bragg peak, particularly inmore » the distal fall-off region. All measurements were made along the central axis of an unmodulated 200-MeV proton beam from a Probeat passive beam-scattering proton accelerator (Hitachi, Ltd., Tokyo, Japan) at varying depths along the Bragg peak. Measurements were made using TLD-100 powder flat packs, placed in a virtual water slab phantom. The measurements were repeated using a parallel plate ionization chamber. The dose measurements using TLD-100 in a proton beam were accurate to within {+-}5.0% of the expected dose, previously seen in our past photon and electron measurements. The ionization chamber and the TLD relative dose measurements agreed well with each other. Absolute dose measurements using TLD agreed with ionization chamber measurements to within {+-} 3.0 cGy, for an exposure of 100 cGy. In our study, the differences in the dose measured by the ionization chamber and those measured by TLD-100 were minimal, indicating that the accuracy and precision of measurements made in the distal fall-off region of a pristine Bragg peak is within the expected range. Thus, the rapid change in stopping power ratios at the end of the range should not affect such measurements, and TLD-100 may be used with confidence as an in vivo dosimeter for proton beam therapy.« less

Nuclear magnetic resonance spectroscopy reveals metabolic changes in living cardiomyocytes after low doses of ionizing radiation.

PubMed

Gramatyka, Michalina; Skorupa, Agnieszka; Sokół, Maria

2018-01-01

Several lines of evidence indicate that exposure of heart to ionizing radiation increases the risk of cardiotoxicity manifested by heart dysfunction and cardiovascular diseases. It was initially believed that the heart is an organ relatively resistant to radiation. Currently, however, it is suspected that even low doses of radiation (< 2 Gy) may have a negative impact on the cardiovascular system. Cardiotoxicity of ionizing radiation is associated with metabolic changes observed in cardiac cells injured by radiation. In this study, we used human cardiomyocytes as a model system, and studied their metabolic response to radiation using high-resolution magic angle spinning nuclear magnetic resonance techniques (HR-MAS NMR). Human cardiomyocytes cultured in vitro were exposed to ionizing radiation and their survival was assessed by clonogenic assay. Changes in apoptosis intensity and cell cycle distribution after the irradiation were measured as well. NMR spectra of cardiomyocytes were acquired using Bruker Avance 400 MHz spectrometer at a spinning rate of 3200 Hz. Survival of cardiomyocytes after NMR experiments was assessed by the Trypan blue exclusion assay. Exposure of cardiomyocytes to small doses of ionizing radiation had no effect on cell proliferation potential and intensity of cell death. However, analysis of metabolic profiles revealed changes in lipids, threonine, glycine, glycerophosphocholine, choline, valine, isoleucine, glutamate, reduced glutathione and taurine metabolism. The results of this study showed that ionizing radiation affects metabolic profiles of cardiomyocytes even at low doses, which potentially have no effect on cell viability.

Physico-Chemical Evaluation of Rationally Designed Melanins as Novel Nature-Inspired Radioprotectors

PubMed Central

Schweitzer, Andrew D.; Howell, Robertha C.; Jiang, Zewei; Bryan, Ruth A.; Gerfen, Gary; Chen, Chin-Cheng; Mah, Dennis; Cahill, Sean

2009-01-01

Background Melanin, a high-molecular weight pigment that is ubiquitous in nature, protects melanized microorganisms against high doses of ionizing radiation. However, the physics of melanin interaction with ionizing radiation is unknown. Methodology/Principal Findings We rationally designed melanins from either 5-S-cysteinyl-DOPA, L-cysteine/L-DOPA, or L-DOPA with diverse structures as shown by elemental analysis and HPLC. Sulfur-containing melanins had higher predicted attenuation coefficients than non-sulfur-containing melanins. All synthetic melanins displayed strong electron paramagnetic resonance (2.14·1018, 7.09·1018, and 9.05·1017 spins/g, respectively), with sulfur-containing melanins demonstrating more complex spectra and higher numbers of stable free radicals. There was no change in the quality or quantity of the stable free radicals after high-dose (30,000 cGy), high-energy (137Cs, 661.6 keV) irradiation, indicating a high degree of radical stability as well as a robust resistance to the ionizing effects of gamma irradiation. The rationally designed melanins protected mammalian cells against ionizing radiation of different energies. Conclusions/Significance We propose that due to melanin's numerous aromatic oligomers containing multiple π-electron system, a generated Compton recoil electron gradually loses energy while passing through the pigment, until its energy is sufficiently low that it can be trapped by stable free radicals present in the pigment. Controlled dissipation of high-energy recoil electrons by melanin prevents secondary ionizations and the generation of damaging free radical species. PMID:19789711

Physico-chemical evaluation of rationally designed melanins as novel nature-inspired radioprotectors.

PubMed

Schweitzer, Andrew D; Howell, Robertha C; Jiang, Zewei; Bryan, Ruth A; Gerfen, Gary; Chen, Chin-Cheng; Mah, Dennis; Cahill, Sean; Casadevall, Arturo; Dadachova, Ekaterina

2009-09-30

Melanin, a high-molecular weight pigment that is ubiquitous in nature, protects melanized microorganisms against high doses of ionizing radiation. However, the physics of melanin interaction with ionizing radiation is unknown. We rationally designed melanins from either 5-S-cysteinyl-DOPA, L-cysteine/L-DOPA, or L-DOPA with diverse structures as shown by elemental analysis and HPLC. Sulfur-containing melanins had higher predicted attenuation coefficients than non-sulfur-containing melanins. All synthetic melanins displayed strong electron paramagnetic resonance (2.14.10(18), 7.09.10(18), and 9.05.10(17) spins/g, respectively), with sulfur-containing melanins demonstrating more complex spectra and higher numbers of stable free radicals. There was no change in the quality or quantity of the stable free radicals after high-dose (30,000 cGy), high-energy ((137)Cs, 661.6 keV) irradiation, indicating a high degree of radical stability as well as a robust resistance to the ionizing effects of gamma irradiation. The rationally designed melanins protected mammalian cells against ionizing radiation of different energies. We propose that due to melanin's numerous aromatic oligomers containing multiple pi-electron system, a generated Compton recoil electron gradually loses energy while passing through the pigment, until its energy is sufficiently low that it can be trapped by stable free radicals present in the pigment. Controlled dissipation of high-energy recoil electrons by melanin prevents secondary ionizations and the generation of damaging free radical species.

Quantitative modeling of total ionizing dose reliability effects in device silicon dioxide layers

NASA Astrophysics Data System (ADS)

Rowsey, Nicole L.

The electrical breakdown of oxides and oxide/semiconductor interfaces is one of the main reasons for device failure in integrated circuits, especially devices under high-stress conditions. One high-stress environment of interest is the space environment. All electronics are vulnerable to ionizing radiation; any high-energy particle that passes through an insulating layer will deposit unwanted charge there, causing shifts in device characteristics. Designing electronics for use in space can be a challenge, because much more energetic radiation exits in space than on Earth, as there is no atmosphere in space to collide with, and thereby reduce the energy of, energetic particles. Although oxide charging due to ionizing radiation creates well-known changes in device characteristics, or total ionizing dose effects, it is still poorly-understood exactly how these changes come about. There are many theories that draw upon a large body of both experimental work and, more recently, quantum-mechanical first principles calculations at the molecular level. This work uses FLOODS, a 3D object-oriented device simulator with multi-physics capability, to investigate these theories, by simulating oxide degradation in realistic device geometries, and comparing the subsequent degradation in device characteristics to experimental measurements. The charge trapping and defect-modulated transport models developed and implemented here have resulted in the first quantitative account of the enhanced low-dose-rate sensitivity effect, and are applicable in a comprehensive range of hydrogen environments. Measurements show that devices exposed to ionizing radiation at high dose rates exhibit less degradation that those exposed at low dose rates. Furthermore, the observed trend differs depending on the amount of hydrogen available before, during, and after irradiation. It is therefore important to understand and take into account the effects of dose rate and hydrogen when developing accelerated testing procedures for devices which have been exposed to various levels of hydrogen during processing and packaging, and which must be deployed in the low-dose-rate space environment. Thus, this work represents a substantial increase in the state-of-the-art, since a quantitative model has not previously been available. The success of the model is due in great part to the use of first-principles calculations of defect and hydrogen bond energies. Vanderbilt collaborators provided the results of these calculations as input to the FLOODS simulations. Using these physical insights, a sensitivity analysis in FLOODS yielded insights into key controlling parameters.

Concentration, physical state, and purity of bacterial endotoxin affect its detoxification by ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Csako, G.; Tsai, C.M.; Hochstein, H.D.

Increasing concentrations of a highly purified bacterial lipopolysaccharide preparation, the U.S. Reference Standard Endotoxin, were exposed to increasing doses of ionizing radiation from a 60Co source. At identical radiation doses both the structural change and Limulus amebocyte lysate (LAL) reactivity were progressively smaller with increasing concentrations of the lipopolysaccharide in an aqueous medium. Under the experimental conditions used, there was a linear relationship between the endotoxin concentration and radiation dose for the structural changes. In contrast to endotoxin in aqueous medium, endotoxin irradiated in its dry state showed no decrease in LAL reactivity and rabbit pyrogenicity. Endotoxin exposed to radiationmore » in water in the presence of albumin showed a much smaller decrease in LAL and pyrogenic activities than expected. The results show that the concentration, physical state, and purity of endotoxin influence its structural and functional alteration by ionizing radiation.« less

Development of a center for light ion therapy and accurate tumor diagnostics at karolinska institutet and hospital

NASA Astrophysics Data System (ADS)

Brahme, Anders; Lind, Bengt K.

2002-04-01

Radiation therapy is today in a state of very rapid development with new intensity modulated treatment techniques continuously being developed. This has made intensity modulated electron and photon beams almost as powerful as conventional uniform beam proton therapy. To be able to cure also the most advanced hypoxic and radiation resistant tumors of complex local spread, intensity modulated light ion beams are really the ultimate tool and only slightly more expensive than proton therapy. The aim of the new center for ion therapy and tumor diagnostics in Stockholm is to develop radiobiologically optimized 3-dimensional pencil beam scanning techniques. Beside the "classical" approaches using low ionization density hydrogen ions (protons, but also deuterons and tritium nuclei) and high ionization density carbon ions, two new approaches will be developed. In the first one lithium or beryllium ions, that induce the least detrimental biological effect to normal tissues for a given biological effect in a small volume of the tumor, will be key particles. In the second approach, referred patients will be given a high-dose high-precision "boost" treatment with carbon or oxygen ions during one week preceding the final treatment with conventional radiations in the referring hospital. The rationale behind these approaches is to reduce the high ionization density dose to the normal tissue stroma inside the tumor and to ensure a microscopically uniform dose delivery. The principal idea of the center is to closely integrate ion therapy into the clinical routine and research of a large radiotherapy department. The light ion therapy center will therefore be combined with advanced tumor diagnostics including MR and PET-CT imaging to facilitate efficient high-precision high-dose boost treatment of remitted patients. The possibility to do 3D tumor diagnostics and 3D dose delivery verification with the same PET camera will be the ultimate step in high quality adaptive radiation therapy where alterations in the delivered dose can be corrected by subsequent treatments

The biobehavioral and neuroimmune impact of low-dose ionizing radiation.

PubMed

York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

2012-02-01

In the clinical setting, repeated exposures (10-30) to low-doses of ionizing radiation (≤200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. Copyright © 2011 Elsevier Inc. All rights reserved.

The biobehavioral and neuroimmune impact of low-dose ionizing radiation

PubMed Central

York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

2011-01-01

In the clinical setting, repeated exposures (10–30) to low-doses of ionizing radiation (≤ 200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 h and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. PMID:21958477

Resveratrol sensitization of DU145 prostate cancer cells to ionizing radiation is associated to ceramide increase.

PubMed

Scarlatti, Francesca; Sala, Giusy; Ricci, Clara; Maioli, Claudio; Milani, Franco; Minella, Marco; Botturi, Marco; Ghidoni, Riccardo

2007-08-08

Radiotherapy is an established therapeutic modality for prostate cancer. Since it is well known that radiotherapy is limited due to its severe toxicity towards normal cells at high dose and minimal effect at low dose, the search for biological compounds that increase the sensitivity of tumors cells to radiation may improve the efficacy of therapy. Resveratrol, a natural antioxidant, was shown to inhibit carcinogenesis in animal models, and to block the process of tumor initiation and progression. The purpose of this study was to examine whether or not resveratrol can sensitize DU145, an androgen-independent human prostate cancer cell line, to ionizing radiation. We report here that DU145 cells are resistant to ionizing radiation-induced cell death, but pretreatment with resveratrol significantly enhances cell death. Resveratrol acts synergistically with ionizing radiation to inhibit cell survival in vitro. Resveratrol also potentiates ionizing radiation-induced ceramide accumulation, by promoting its de novo biosynthesis. This confirms ceramide as an effective mediator of the anticancer potential induced by resveratrol.

Clustered DNA damages induced in isolated DNA and in human cells by low doses of ionizing radiation

NASA Technical Reports Server (NTRS)

Sutherland, B. M.; Bennett, P. V.; Sidorkina, O.; Laval, J.; Lowenstein, D. I. (Principal Investigator)

2000-01-01

Clustered DNA damages-two or more closely spaced damages (strand breaks, abasic sites, or oxidized bases) on opposing strands-are suspects as critical lesions producing lethal and mutagenic effects of ionizing radiation. However, as a result of the lack of methods for measuring damage clusters induced by ionizing radiation in genomic DNA, neither the frequencies of their production by physiological doses of radiation, nor their repairability, nor their biological effects are known. On the basis of methods that we developed for quantitating damages in large DNAs, we have devised and validated a way of measuring ionizing radiation-induced clustered lesions in genomic DNA, including DNA from human cells. DNA is treated with an endonuclease that induces a single-strand cleavage at an oxidized base or abasic site. If there are two closely spaced damages on opposing strands, such cleavage will reduce the size of the DNA on a nondenaturing gel. We show that ionizing radiation does induce clustered DNA damages containing abasic sites, oxidized purines, or oxidized pyrimidines. Further, the frequency of each of these cluster classes is comparable to that of frank double-strand breaks; among all complex damages induced by ionizing radiation, double-strand breaks are only about 20%, with other clustered damage constituting some 80%. We also show that even low doses (0.1-1 Gy) of high linear energy transfer ionizing radiation induce clustered damages in human cells.

Alloy nanoparticle synthesis using ionizing radiation

DOEpatents

Nenoff, Tina M [Sandia Park, NM; Powers, Dana A [Albuquerque, NM; Zhang, Zhenyuan [Durham, NC

2011-08-16

A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

Pretreatment of low dose radiation reduces radiation-induced apoptosis in mouse lymphoma (EL4) cells.

PubMed

Kim, J H; Hyun, S J; Yoon, M Y; Ji, Y H; Cho, C K; Yoo, S Y

1997-06-01

Induction of an adaptive response to ionizing radiation in mouse lymphoma (EL4) cells was studied by using cell survival fraction and apoptotic nucleosomal DNA fragmentation as biological end points. Cells in early log phase were pre-exposed to low dose of gamma-rays (0.01 Gy) 4 or 20 hrs prior to high dose gamma-ray (4, 8 and 12 Gy for cell survival fraction analysis; 8 Gy for DNA fragmentation analysis) irradiation. Then cell survival fractions and the extent of DNA fragmentation were measured. Significant adaptive response, increase in cell survival fraction and decrease in the extent of DNA fragmentation were induced when low and high dose gamma-ray irradiation time interval was 4 hr. Addition of protein or RNA synthesis inhibitor, cycloheximide or 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole (DRFB), respectively during adaptation period, the period from low dose gamma-ray irradiation to high dose gamma-ray irradiation, was able to inhibit the induction of adaptive response, which is the reduction of the extent DNA fragmentation in irradiated EL4 cells. These data suggest that the induction of adaptive response to ionizing radiation in EL4 cells required both protein and RNA synthesis.

LiF TLD-100 as a dosimeter in high energy proton beam therapy--can it yield accurate results?

PubMed

Zullo, John R; Kudchadker, Rajat J; Zhu, X Ronald; Sahoo, Narayan; Gillin, Michael T

2010-01-01

In the region of high-dose gradients at the end of the proton range, the stopping power ratio of the protons undergoes significant changes, allowing for a broad spectrum of proton energies to be deposited within a relatively small volume. Because of the potential linear energy transfer dependence of LiF TLD-100 (thermolumescent dosimeter), dose measurements made in the distal fall-off region of a proton beam may be less accurate than those made in regions of low-dose gradients. The purpose of this study is to determine the accuracy and precision of dose measured using TLD-100 for a pristine Bragg peak, particularly in the distal fall-off region. All measurements were made along the central axis of an unmodulated 200-MeV proton beam from a Probeat passive beam-scattering proton accelerator (Hitachi, Ltd., Tokyo, Japan) at varying depths along the Bragg peak. Measurements were made using TLD-100 powder flat packs, placed in a virtual water slab phantom. The measurements were repeated using a parallel plate ionization chamber. The dose measurements using TLD-100 in a proton beam were accurate to within +/-5.0% of the expected dose, previously seen in our past photon and electron measurements. The ionization chamber and the TLD relative dose measurements agreed well with each other. Absolute dose measurements using TLD agreed with ionization chamber measurements to within +/- 3.0 cGy, for an exposure of 100 cGy. In our study, the differences in the dose measured by the ionization chamber and those measured by TLD-100 were minimal, indicating that the accuracy and precision of measurements made in the distal fall-off region of a pristine Bragg peak is within the expected range. Thus, the rapid change in stopping power ratios at the end of the range should not affect such measurements, and TLD-100 may be used with confidence as an in vivo dosimeter for proton beam therapy. Copyright 2010 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Evidence for formation of DNA repair centers and dose-response nonlinearity in human cells

PubMed Central

Neumaier, Teresa; Swenson, Joel; Pham, Christopher; Polyzos, Aris; Lo, Alvin T.; Yang, PoAn; Dyball, Jane; Asaithamby, Aroumougame; Chen, David J.; Bissell, Mina J.; Thalhammer, Stefan; Costes, Sylvain V.

2012-01-01

The concept of DNA “repair centers” and the meaning of radiation-induced foci (RIF) in human cells have remained controversial. RIFs are characterized by the local recruitment of DNA damage sensing proteins such as p53 binding protein (53BP1). Here, we provide strong evidence for the existence of repair centers. We used live imaging and mathematical fitting of RIF kinetics to show that RIF induction rate increases with increasing radiation dose, whereas the rate at which RIFs disappear decreases. We show that multiple DNA double-strand breaks (DSBs) 1 to 2 μm apart can rapidly cluster into repair centers. Correcting mathematically for the dose dependence of induction/resolution rates, we observe an absolute RIF yield that is surprisingly much smaller at higher doses: 15 RIF/Gy after 2 Gy exposure compared to approximately 64 RIF/Gy after 0.1 Gy. Cumulative RIF counts from time lapse of 53BP1-GFP in human breast cells confirmed these results. The standard model currently in use applies a linear scale, extrapolating cancer risk from high doses to low doses of ionizing radiation. However, our discovery of DSB clustering over such large distances casts considerable doubts on the general assumption that risk to ionizing radiation is proportional to dose, and instead provides a mechanism that could more accurately address risk dose dependency of ionizing radiation. PMID:22184222

Radiation measurements aboard the fourth Gemini flight.

PubMed

Janni, J F; Schneider, M F

1967-01-01

Two special tissue-equivalent ionization chambers and 5 highly sensitive passive dosimetry packages were flown aboard the recent Gemini 4 flight for the purpose of obtaining precise values of instantaneous dose rate, accumulated dose. and shielding effectiveness. This experiment marked the first time that well-defined tissue dose and radiation survey measurements have been carried out in manned spaceflight operations. Since all measurements were accomplished under normal spacecraft environmental conditions, the biological dose resulted primarily from trapped inner Van Allen Belt radiation encountered by the spacecraft in the South Atlantic Anomaly. The experiment determined the particle type, ionizing and penetrating power, and variation with time and position within the Gemini spacecraft. Measured dose rates ranged from 100 mrad/hr for passes penetrating deeply into the South Atlantic Anomaly to less than 0.1 mrad/hr from lower latitude cosmic radiation. The accumulated tissue dose measured by the active ionization chambers, shielded by 0.4 gm/cm2 for the 4-day mission, was 82 mrad. Since the 5 passive dosimetry packages were each located in different positions within the spacecraft, the total mission surface dose measured by these detectors varied from 73 to 27 mrad, depending upon location and shielding. The particles within the spacecraft were recorded in nuclear emulsion, which established that over 90% of the tissue dose was attributable to penetrating protons. This experiment indicates that the radiation environment under shielded conditions at Gemini altitudes was not hazardous.

Radiation Safety in Children With Congenital and Acquired Heart Disease: A Scientific Position Statement on Multimodality Dose Optimization From the Image Gently Alliance.

PubMed

Hill, Kevin D; Frush, Donald P; Han, B Kelly; Abbott, Brian G; Armstrong, Aimee K; DeKemp, Robert A; Glatz, Andrew C; Greenberg, S Bruce; Herbert, Alexander Sheldon; Justino, Henri; Mah, Douglas; Mahesh, Mahadevappa; Rigsby, Cynthia K; Slesnick, Timothy C; Strauss, Keith J; Trattner, Sigal; Viswanathan, Mohan N; Einstein, Andrew J

2017-07-01

There is a need for consensus recommendations for ionizing radiation dose optimization during multimodality medical imaging in children with congenital and acquired heart disease (CAHD). These children often have complex diseases and may be exposed to a relatively high cumulative burden of ionizing radiation from medical imaging procedures, including cardiac computed tomography, nuclear cardiology studies, and fluoroscopically guided diagnostic and interventional catheterization and electrophysiology procedures. Although these imaging procedures are all essential to the care of children with CAHD and have contributed to meaningfully improved outcomes in these patients, exposure to ionizing radiation is associated with potential risks, including an increased lifetime attributable risk of cancer. The goal of these recommendations is to encourage informed imaging to achieve appropriate study quality at the lowest achievable dose. Other strategies to improve care include a patient-centered approach to imaging, emphasizing education and informed decision making and programmatic approaches to ensure appropriate dose monitoring. Looking ahead, there is a need for standardization of dose metrics across imaging modalities, so as to encourage comparative effectiveness studies across the spectrum of CAHD in children. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA Goddard Space Flight Center and NASA Electronic Parts and Packaging Program

NASA Technical Reports Server (NTRS)

Topper, Alyson D.; Campola, Michael J.; Chen, Dakai; Casey, Megan C.; Yau, Ka-Yen; Cochran, Donna J.; Label, Kenneth A.; Ladbury, Raymond L.; Mondy, Timothy K.; O'Bryan, Martha V.;

Low- and high-LET radiation drives clonal expansion of lung progenitor cells in vivo

PubMed Central

Farin, Alicia M.; Manzo, Nicholas D.; Kirsch, David G.; Stripp, Barry R.

2015-01-01

Abundant populations of epithelial progenitor cells maintain the epithelium along the proximal-to-distal axis of the airway. Exposure of lung tissue to ionizing radiation leads to tissue remodeling and potential cancer initiation or progression. However, little is known about the effects of ionizing radiation on airway epithelial progenitor cells. We hypothesized that ionizing radiation exposure will alter the behavior of airway epithelial progenitor cells in a radiation dose- and quality-dependent manner. To address this hypothesis, we cultured primary airway epithelial cells isolated from mice exposed to various doses of 320 kVp X-ray or 600 MeV/nucleon 56Fe ions in a 3D epithelial-fibroblast co-culture system. Colony-forming efficiency of the airway epithelial progenitor cells was assessed at culture day 14. In vivo clonogenic and proliferative potentials of airway epithelial progenitor cells were measured after exposure to ionizing radiation by lineage tracing and IdU incorporation. Exposure to both X-rays and 56Fe resulted in a dose dependent decrease in the ability of epithelial progenitors to form colonies in vitro. In vivo evidence for increased clonogenic expansion of epithelial progenitors was observed after exposure to both X-rays and 56Fe. Interestingly, we found no significant increase in the epithelial proliferative index, indicating that ionizing radiation does not promote increased turnover of the airway epithelium. Therefore, we propose a model in which radiation induces a dose-dependent decrease in the pool of available progenitor cells, leaving fewer progenitors able to maintain the airway long-term. This work provides novel insights into the effects of ionizing radiation exposure on airway epithelial progenitor cell behavior. PMID:25564721

Mechanism of action for anti-radiation vaccine in reducing the biological impact of high-dose gamma irradiation

NASA Astrophysics Data System (ADS)

Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after high-dose gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naïve animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which they mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

Radiation Dose-Response Relationships and Risk Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strom, Daniel J.

The notion of a dose-response relationship was probably invented shortly after the discovery of poisons, the invention of alcoholic beverages, and the bringing of fire into a confined space in the forgotten depths of ancient prehistory. The amount of poison or medicine ingested can easily be observed to affect the behavior, health, or sickness outcome. Threshold effects, such as death, could be easily understood for intoxicants, medicine, and poisons. As Paracelsus (1493-1541), the 'father' of modern toxicology said, 'It is the dose that makes the poison.' Perhaps less obvious is the fact that implicit in such dose-response relationships is alsomore » the notion of dose rate. Usually, the dose is administered fairly acutely, in a single injection, pill, or swallow; a few puffs on a pipe; or a meal of eating or drinking. The same amount of intoxicants, medicine, or poisons administered over a week or month might have little or no observable effect. Thus, before the discovery of ionizing radiation in the late 19th century, toxicology ('the science of poisons') and pharmacology had deeply ingrained notions of dose-response relationships. This chapter demonstrates that the notion of a dose-response relationship for ionizing radiation is hopelessly simplistic from a scientific standpoint. While useful from a policy or regulatory standpoint, dose-response relationships cannot possibly convey enough information to describe the problem from a quantitative view of radiation biology, nor can they address societal values. Three sections of this chapter address the concepts, observations, and theories that contribute to the scientific input to the practice of managing risks from exposure to ionizing radiation. The presentation begins with irradiation regimes, followed by responses to high and low doses of ionizing radiation, and a discussion of how all of this can inform radiation risk management. The knowledge that is really needed for prediction of individual risk is presented. The chapter ends with conclusions and recommendations.« less

Computer model to simulate ionizing radiation effects correlates with experimental data

NASA Astrophysics Data System (ADS)

Perez-Poch, Antoni

Exposure to radiation from high energy protons and particles with ionizing properties is a major challenge for long-term space missions. The specific effect of such radiation on hematopoietic cells is still not fully understood. A number of experiments have been conducted on ground and in space. Those experiments on one hand, measure the extent of damage on blood markers. On the other hand, they intend to quantify the correlation between dose and energy from the radiation particles, with their ability to impair the hematopoietic stem and progenitor function. We present a computer model based on a neural network that intends to assess the relationship between dose, energy and number of hits on a particular cell, to the damage incurred to the human marrow cells. Calibration of the network is performed with the existing experimental data available in bibliography. Different sources of ionizing radiation at different doses (0-90 cGy) and along different patterns of a long-term exposure scenarios are simulated. Results are shown for a continuous variation of doses and are compared with specific data available in the literature. Some predictions are inferred for long-term scenarios of spaceflight, and the risk of jeopardizing a mission due to a major disfunction of the bone marrow is calculated. The method has proved successful in reproducing specific experimental data. We also discuss the significance and validity of the predicted ionizing radiation effects in situations such as long-term missions for a continuous range of dose.

Micro RNA responses to chronic or acute exposures to low dose ionizing radiation

PubMed Central

Chaudhry, M. Ahmad; Omaruddin, Romaica A.; Kreger, Bridget; de Toledo, Sonia M.; Azzam, Edouard I.

2014-01-01

Human health risks of exposure to low dose ionizing radiation remain ambiguous and are the subject of intense debate. A wide variety of biological effects are induced after cellular exposure to ionizing radiation, but the underlying molecular mechanism(s) remain to be completely understood. We hypothesized that low dose c-radiation-induced effects are controlled by the modulation of micro RNA (miRNA) that participate in the control of gene expression at the posttranscriptional level and are involved in many cellular processes. We monitored the expression of several miRNA in human cells exposed to acute or chronic low doses of 10 cGy or a moderate dose of 400 cGy of 137Cs γ-rays. Dose, dose rate and time dependent differences in the relative expression of several miRNA were investigated. The expression patterns of many miRNA differed after exposure to either chronic or acute 10 cGy. The expression of miRNA let-7e, a negative regulator of RAS oncogene, and the c-MYC miRNA cluster were upregulated after 10 cGy chronic dose but were downregulated after 3 h of acute 10 cGy. The miR-21 was upregulated in chronic or acute low dose and moderate dose treated cells and its target genes hPDCD4, hPTEN, hSPRY2, and hTPM1 were found to be downregulated. These findings provide evidence that low dose and dose rate c-irradiation dictate the modulation of miRNA, which can result in a differential cellular response than occurs at high doses. This information will contribute to understanding the risks to human health after exposure to low dose radiation. PMID:22367372

Atmospheric Ionizing Radiation (AIR) ER-2 Preflight Analysis

NASA Technical Reports Server (NTRS)

Tai, Hsiang; Wilson, John W.; Maiden, D. L.

1998-01-01

Atmospheric ionizing radiation (AIR) produces chemically active radicals in biological tissues that alter the cell function or result in cell death. The AIR ER-2 flight measurements will enable scientists to study the radiation risk associated with the high-altitude operation of a commercial supersonic transport. The ER-2 radiation measurement flights will follow predetermined, carefully chosen courses to provide an appropriate database matrix which will enable the evaluation of predictive modeling techniques. Explicit scientific results such as dose rate, dose equivalent rate, magnetic cutoff, neutron flux, and air ionization rate associated with those flights are predicted by using the AIR model. Through these flight experiments, we will further increase our knowledge and understanding of the AIR environment and our ability to assess the risk from the associated hazard.

Low-Dose Ionizing Radiation Exposure, Oxidative Stress and Epigenetic Programing of Health and Disease.

PubMed

Tharmalingam, Sujeenthar; Sreetharan, Shayenthiran; Kulesza, Adomas V; Boreham, Douglas R; Tai, T C

2017-10-01

Ionizing radiation exposure from medical diagnostic imaging has greatly increased over the last few decades. Approximately 80% of patients who undergo medical imaging are exposed to low-dose ionizing radiation (LDIR). Although there is widespread consensus regarding the harmful effects of high doses of radiation, the biological effects of low-linear energy transfer (LET) LDIR is not well understood. LDIR is known to promote oxidative stress, however, these levels may not be large enough to result in genomic mutations. There is emerging evidence that oxidative stress causes heritable modifications via epigenetic mechanisms (DNA methylation, histone modification, noncoding RNA regulation). These epigenetic modifications result in permanent cellular transformations without altering the underlying DNA nucleotide sequence. This review summarizes the major concepts in the field of epigenetics with a focus on the effects of low-LET LDIR (<100 mGy) and oxidative stress on epigenetic gene modification. In this review, we show evidence that suggests that LDIR-induced oxidative stress provides a mechanistic link between LDIR and epigenetic gene regulation. We also discuss the potential implication of LDIR exposure during pregnancy where intrauterine fetal development is highly susceptible to oxidative stress-induced epigenetic programing.

Dose equivalent near the bone-soft tissue interface from nuclear fragments produced by high-energy protons

NASA Technical Reports Server (NTRS)

Shavers, M. R.; Poston, J. W.; Cucinotta, F. A.; Wilson, J. W.

1996-01-01

During manned space missions, high-energy nucleons of cosmic and solar origin collide with atomic nuclei of the human body and produce a broad linear energy transfer spectrum of secondary particles, called target fragments. These nuclear fragments are often more biologically harmful than the direct ionization of the incident nucleon. That these secondary particles increase tissue absorbed dose in regions adjacent to the bone-soft tissue interface was demonstrated in a previous publication. To assess radiological risks to tissue near the bone-soft tissue interface, a computer transport model for nuclear fragments produced by high energy nucleons was used in this study to calculate integral linear energy transfer spectra and dose equivalents resulting from nuclear collisions of 1-GeV protons transversing bone and red bone marrow. In terms of dose equivalent averaged over trabecular bone marrow, target fragments emitted from interactions in both tissues are predicted to be at least as important as the direct ionization of the primary protons-twice as important, if recently recommended radiation weighting factors and "worst-case" geometry are used. The use of conventional dosimetry (absorbed dose weighted by aa linear energy transfer-dependent quality factor) as an appropriate framework for predicting risk from low fluences of high-linear energy transfer target fragments is discussed.

Detecting ionizing radiation with optical fibers down to biomedical doses

NASA Astrophysics Data System (ADS)

Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; De Natale, P.; Gagliardi, G.

2013-10-01

We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10-4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.

Sparsely Ionizing Diagnostic and Natural Background Radiations are Likely Preventing Cancer and Other Genomic-Instability-Associated Diseases

PubMed Central

Scott, Bobby R.; Di Palma, Jennifer

2007-01-01

Routine diagnostic X-rays (e.g., chest X-rays, mammograms, computed tomography scans) and routine diagnostic nuclear medicine procedures using sparsely ionizing radiation forms (e.g., beta and gamma radiations) stimulate the removal of precancerous neo-plastically transformed and other genomically unstable cells from the body (medical radiation hormesis). The indicated radiation hormesis arises because radiation doses above an individual-specific stochastic threshold activate a system of cooperative protective processes that include high-fidelity DNA repair/apoptosis (presumed p53 related), an auxiliary apoptosis process (PAM process) that is presumed p53-independent, and stimulated immunity. These forms of induced protection are called adapted protection because they are associated with the radiation adaptive response. Diagnostic X-ray sources, other sources of sparsely ionizing radiation used in nuclear medicine diagnostic procedures, as well as radioisotope-labeled immunoglobulins could be used in conjunction with apopto-sis-sensitizing agents (e.g., the natural phenolic compound resveratrol) in curing existing cancer via low-dose fractionated or low-dose, low-dose-rate therapy (therapeutic radiation hormesis). Evidence is provided to support the existence of both therapeutic (curing existing cancer) and medical (cancer prevention) radiation hormesis. Evidence is also provided demonstrating that exposure to environmental sparsely ionizing radiations, such as gamma rays, protect from cancer occurrence and the occurrence of other diseases via inducing adapted protection (environmental radiation hormesis). PMID:18648608

The influence of ionizing radiation, temperature, and light on eplerenone in the solid state.

PubMed

Dettlaff, Katarzyna; Ogrodowczyk, Magdalena; Kycler, Witold; Dołhań, Agnieszka; Cwiertnia, Barbara; Garbacki, Piotr; Jelińska, Anna

2014-01-01

Eplerenone was subjected to the influence of ionizing radiation in the form of a high-energy electron beam (25-400 kGy), high temperature (90°C RH 0% and 60°C RH 76.4%), and light (6 mln lux h). An HPLC method was used to determine the content of eplerenone and to establish the impurity profile of all samples. As eplerenone was found to be a compound of great resistance to the above stress factors with the exception of high doses of ionizing radiation (≥ 200 kGy) when its degradation was above 1%, it is possible to sterilize eplerenone by radiation method with the standard dose of 25 kGy. Based on the analysis of impurities and degradation products, the mechanism of radiodegradation was demonstrated to differ from the mechanisms of photo- and thermodegradation. The observation that the DSC curves for the nondegraded and degraded samples of eplerenone were significantly different only under exposure to the electron beam confirmed the applicability of DSC for studies of radiolytic degradation of eplerenone.

Effects of ionizing radiation on the immune system with special emphasis on the interaction of dendritic and T cells.

PubMed

Manda, Katrin; Glasow, Annegret; Paape, Daniel; Hildebrandt, Guido

2012-01-01

Dendritic cells (DCs), as professional antigen-presenting cells, are members of the innate immune system and function as key players during the induction phase of adaptive immune responses. Uptake, processing, and presentation of antigens direct the outcome toward either tolerance or immunity. The cells of the immune system are among the most highly radiosensitive cells in the body. For high doses of ionizing radiation (HD-IR) both immune-suppressive effects after whole body irradiation and possible immune activation during tumor therapy were observed. On the other hand, the effects of low doses of ionizing radiation (LD-IR) on the immune system are controversial and seem to show high variability among different individuals and species. There are reports revealing that protracted LD-IR can result in radioresistance. But immune-suppressive effects of chronic LD-IR are also reported, including the killing or sensitizing of certain cell types. This article shall review the current knowledge of radiation-induced effects on the immune system, paying special attention to the interaction of DCs and T cells.

Identification of Differential Gene Expression Patterns after Acute Exposure to High and Low Doses of Low-LET Ionizing Radiation in a Reconstituted Human Skin Tissue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tilton, Susan C.; Markillie, Lye Meng; Hays, Spencer

Our goal here was to identify dose and temporal dependent radiation responses in a complex tissue, reconstituted human skin. Direct sequencing of RNA (RNA-seq) was used to quantify altered transcripts following exposure to 0.1, 2 and 10 Gy of ionizing radiation at 3 and 8 hours. These doses include a low dose in the range of some medical diagnostic procedures (0.1 Gy), a dose typically received during radiotherapy (2.0 Gy) and a lethal dose (10 Gy). These doses could be received after an intentional or accidental radiation exposure and biomarkers are needed to rapidly and accurately triage exposed individuals. Amore » total of 1701 genes were deemed to be significantly affected by high dose radiation exposure with the majority of genes affected at 10 Gy. A group of 29 genes including GDF15, BBC3, PPM1D, FDXR, GADD45A, MDM2, CDKN1A, TP53INP1, CYCSP27, SESN1, SESN2, PCNA, and AEN were similarly altered at both 2 and 10 Gy, but not 0.1 Gy, at multiple time points. A much larger group of up regulated genes, including those involved in inflammatory responses, was significantly altered only after a 10 Gy exposure. At high doses, down regulated genes were associated with cell cycle regulation and exhibited an apparent linear response between 2 and 10 Gy. While only a handful of genes were significantly affected by 0.1 Gy exposure using stringent statistical filters, groups of related genes regulating cell cycle progression and inflammatory responses consistently exhibited opposite trends in their regulation compared to the high dose exposures. Differential regulation of PLK1 signaling at low and high doses was confirmed using qRT-PCR. These results indicate that some alterations in gene expression are qualitatively different at low and high doses of radiation in this model system.« less

CARCINOGENIC EFFECTS OF LOW DOSES OF IONIZING RADIATION

EPA Science Inventory

Carcinogenic Effects of Low Doses of Ionizing Radiation

R Julian Preston, Environmental Carcinogenesis Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711

The form of the dose-response curve for radiation-induced cancers, particu...

Free radical production by high energy shock waves--comparison with ionizing irradiation.

PubMed

Morgan, T R; Laudone, V P; Heston, W D; Zeitz, L; Fair, W R

1988-01-01

Fricke chemical dosimetry is used as an indirect measure of the free radical production of ionizing irradiation. We adapted the Fricke ferrous sulfate radiation dosimeter to examine the chemical effects of high energy shock waves. Significant free radical production was documented. The reaction was dose dependent, predictably increased by acoustic impedance, but curvilinear. A thousand shocks at 18 kilovolts induced the same free radical oxidation as 1100 rad cobalt-60 gamma ionizing irradiation, increasing to 2900 rad in the presence of an air-fluid zone of acoustic impedance. The biological effect of these free radicals was compared to that of cobalt-60 ionizing irradiation by measuring the affect on Chinese hamster cells by clonogenic assay. While cobalt-60 irradiation produced a marked decrease in clonogenic survivors, little effect was noted with high energy shock waves. This suggested that the chemical effects produced by shock waves were either absent or attenuated in the cells, or were inherently less toxic than those of ionizing irradiation.

Oxidation of Carbon Nanotubes in an Ionizing Environment.

PubMed

Koh, Ai Leen; Gidcumb, Emily; Zhou, Otto; Sinclair, Robert

2016-02-10

In this work, we present systematic studies on how an illuminating electron beam which ionizes molecular gas species can influence the mechanism of carbon nanotube oxidation in an environmental transmission electron microscope (ETEM). We found that preferential attack of the nanotube tips is much more prevalent than for oxidation in a molecular gas environment. We establish the cumulative electron doses required to damage carbon nanotubes from 80 keV electron beam irradiation in gas versus in high vacuum. Our results provide guidelines for the electron doses required to study carbon nanotubes within or without a gas environment, to determine or ameliorate the influence of the imaging electron beam. This work has important implications for in situ studies as well as for the oxidation of carbon nanotubes in an ionizing environment such as that occurring during field emission.

Environmental standards for ionizing radiation: theoretical basis for dose-response curves.

PubMed Central

Upton, A C

1983-01-01

The types of injury attributable to ionizing radiation are subdivided, for purposes of risk assessment and radiological protection, into two broad categories: stochastic effects and nonstochastic effects. Stochastic effects are viewed as probablistic phenomena, varying in frequency but not severity as a function of the dose, without any threshold; nonstochastic effects are viewed as deterministic phenomena, varying in both frequency and severity as a function of the dose, with clinical thresholds. Included among stochastic effects are heritable effects (mutations and chromosome aberrations) and carcinogenic effects. Both types of effects are envisioned as unicellular phenomena which can result from nonlethal injury of individual cells, without the necessity of damage to other cells. For the induction of mutations and chromosome aberrations in the low-to-intermediate dose range, the dose-response curve with high-linear energy transfer (LET) radiation generally conforms to a linear nonthreshold relationship and varies relatively little with the dose rate. In contrast, the curve with low-LET radiation generally conforms to a linear-quadratic relationship, rising less steeply than the curve with high-LET radiation and increasing in slope with increasing dose and dose rate. The dose-response curve for carcinogenic effects varies widely from one type of neoplasm to another in the intermediate-to-high dose range, in part because of differences in the way large doses of radiation can affect the promotion and progression of different neoplasms. Information about dose-response relations for low-level irradiation is fragmentary but consistent, in general, with the hypothesis that the neoplastic transformation may result from mutation, chromosome aberration or genetic recombination in a single susceptible cell. PMID:6653536

Total Ionizing Dose Test Report for the UC1823A Pulse Width Modulator

NASA Technical Reports Server (NTRS)

Chen, Dakai; Forney, James

2017-01-01

The purpose of this study is to examine the total ionizing dose susceptibility for the UC1823A pulse width modulator manufactured by Texas Instruments, Inc. The part is suspected to be vulnerable to enhanced low dose rate sensitivity (ELDRS).

Quantitative Proteomic Profiling of Low Dose Ionizing Radiation Effects in a Human Skin Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hengel, Shawna; Aldrich, Joshua T.; Waters, Katrina M.

2014-07-29

To assess molecular responses to low doses of radiation that may be encountered during medical diagnostic procedures, nuclear accidents, or terrorist acts, a quantitative global proteomic approach was used to identify protein alterations in a reconstituted human skin tissue treated with 10 cGy of ionizing radiation. Subcellular fractionation was employed to remove highly abundant structural proteins and provide insight on radiation induced alterations in protein abundance and localization. In addition, peptides were post-fractionated using high resolution 2-dimensional liquid chromatography to increase the dynamic range of detection of protein abundance and translocation changes. Quantitative data was obtained by labeling peptides withmore » 8-plex isobaric iTRAQ tags. A total of 207 proteins were detected with statistically significant alterations in abundance and/or subcellular localization compared to sham irradiated tissues. Bioinformatics analysis of the data indicated that the top canonical pathways affected by low dose radiation are related to cellular metabolism. Among the proteins showing alterations in abundance, localization and proteolytic processing was the skin barrier protein filaggrin which is consistent with our previous observation that ionizing radiation alters profilaggrin processing with potential effects on skin barrier functions. In addition, a large number of proteases and protease regulators were affected by low dose radiation exposure indicating that altered proteolytic activity may be a hallmark of low dose radiation exposure. While several studies have demonstrated altered transcriptional regulation occurs following low dose radiation exposures, the data presented here indicates post-transcriptional regulation of protein abundance, localization, and proteolytic processing play an important role in regulating radiation responses in complex human tissues.« less

Radiation dose management for pediatric cardiac computed tomography: a report from the Image Gently 'Have-A-Heart' campaign.

PubMed

Rigsby, Cynthia K; McKenney, Sarah E; Hill, Kevin D; Chelliah, Anjali; Einstein, Andrew J; Han, B Kelly; Robinson, Joshua D; Sammet, Christina L; Slesnick, Timothy C; Frush, Donald P

2018-01-01

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently "Have-A-Heart" campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease.

Generation of polypeptide-templated gold nanoparticles using ionizing radiation.

PubMed

Walker, Candace Rae; Pushpavanam, Karthik; Nair, Divya Geetha; Potta, Thrimoorthy; Sutiyoso, Caesario; Kodibagkar, Vikram D; Sapareto, Stephen; Chang, John; Rege, Kaushal

2013-08-13

Ionizing radiation, including γ rays and X-rays, are high-energy electromagnetic radiation with diverse applications in nuclear energy, astrophysics, and medicine. In this work, we describe the use of ionizing radiation and cysteine-containing elastin-like polypeptides (C(n)ELPs, where n = 2 or 12 cysteines in the polypeptide sequence) for the generation of gold nanoparticles. In the presence of C(n)ELPs, ionizing radiation doses higher than 175 Gy resulted in the formation of maroon-colored gold nanoparticle dispersions, with maximal absorbance at 520 nm, from colorless metal salts. Visible color changes were not observed in any of the control systems, indicating that ionizing radiation, gold salt solution, and C(n)ELPs were all required for nanoparticle formation. The hydrodynamic diameters of nanoparticles, determined using dynamic light scattering, were in the range of 80-150 nm, while TEM imaging indicated the formation of gold cores 10-20 nm in diameter. Interestingly, C2ELPs formed 1-2 nm diameter gold nanoparticles in the absence of radiation. Our results describe a facile method of nanoparticle formation in which nanoparticle size can be tailored based on radiation dose and C(n)ELP type. Further improvements in these polypeptide-based systems can lead to colorimetric detection of ionizing radiation in a variety of applications.

Intercomparison of standards of absorbed dose between the USSR and the UK

NASA Astrophysics Data System (ADS)

Berlyand, V. A.; Bregadze, J. I.; Burns, J. E.; Dusautoy, A. R.; Sharpe, P. H. G.

1991-05-01

A comparison of national standards of absorbed dose was carried out between the All-Union Research Institute for Physical Technical and Radiotechnical Measurements (VNIIFTRI), USSR, and the National Physical Laboratotry (NPL), UK (United Kingdom). Absorbed dose to water for cobalt 60 gamma radiation was compared by means of Fricke dosimeters and ionization chambers in 1985 and 1986. The primary standards used to derive absorbed dose to water were cavity ionization chambers at NPL and a graphite calorimeter at VNIIFTRI. The ratio of absorbed dose to water, NPL to VNIIFTRI, using Fricke dosimeters was 1.008; using ionization chambers it was 1.007. This agreement is within the estimated uncertainties of the standards and measurement methods.

Effect of gamma-irradiation on the levels of total and cis/trans isomers of beta-carotene in dehydrated parsley

NASA Astrophysics Data System (ADS)

Sebastião, Kátia I.; Almeida-Muradian, Lígia B.; Romanelli, Maria Fernanda; Koseki, Paula Massae; Villavicencio, Anna Lúcia C. H.

2002-03-01

Ionizing radiation is a method for preservation of foods that use the high energy of gamma rays or accelerated electrons, thereby ionizing molecules. The most important precursor of vitamin A is β-carotene, a carotenoid with pro-vitamin A activity. The highly unsaturated chain confers the instability of β-carotene, and some reactions, as isomerisation, can reduce the characteristics of pro-vitamin A. The present study investigated whether increasing doses of 0, 10 and 20 kGy lower the total β-carotene level and if an enhancement of cis-isomers occurred on samples of dehydrated parsley. No differences were observed of either fractions analyzed at doses applied in this study, nor did it contribute to the decrease of vitamin A.

Physical and biological properties of U. S. standard endotoxin EC after exposure to ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Csako, G.; Elin, R.J.; Hochstein, H.D.

Techniques that reduce the toxicity of bacterial endotoxins are useful for studying the relationship between structure and biological activity. We used ionizing radiation to detoxify a highly refined endotoxin preparation. U.S. standard endotoxin EC. Dose-dependent changes occurred by exposure to /sup 60/Co-radiation in the physical properties and biological activities of the endotoxin. Sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis showed gradual loss of the polysaccharide components (O-side chain and R-core) from the endotoxin molecules. In contrast, although endotoxin revealed a complex absorption pattern in the UV range, radiation treatment failed to modify that pattern. Dose-related destruction of the primary toxic component,more » lipid A, was suggested by the results of activity tests: both the pyrogenicity and limulus reactivity of the endotoxin were destroyed by increasing doses of radiation. The results indicate that the detoxification is probably due to multiple effects of the ionizing radiation on bacterial lipopolysaccharides, and the action involves (i) the destruction of polysaccharide moieties and possibly (ii) the alteration of lipid A component of the endotoxin molecule.« less

Ionization chamber-based reference dosimetry of intensity modulated radiation beams.

PubMed

Bouchard, Hugo; Seuntjens, Jan

2004-09-01

The present paper addresses reference dose measurements using thimble ionization chambers for quality assurance in IMRT fields. In these radiation fields, detector fluence perturbation effects invalidate the application of open-field dosimetry protocol data for the derivation of absorbed dose to water from ionization chamber measurements. We define a correction factor C(Q)IMRT to correct the absorbed dose to water calibration coefficient N(D, w)Q for fluence perturbation effects in individual segments of an IMRT delivery and developed a calculation method to evaluate the factor. The method consists of precalculating, using accurate Monte Carlo techniques, ionization chamber, type-dependent cavity air dose, and in-phantom dose to water at the reference point for zero-width pencil beams as a function of position of the pencil beams impinging on the phantom surface. These precalculated kernels are convolved with the IMRT fluence distribution to arrive at the dose-to-water-dose-to-cavity air ratio [D(a)w (IMRT)] for IMRT fields and with a 10x10 cm2 open-field fluence to arrive at the same ratio D(a)w (Q) for the 10x10 cm2 reference field. The correction factor C(Q)IMRT is then calculated as the ratio of D(a)w (IMRT) and D(a)w (Q). The calculation method was experimentally validated and the magnitude of chamber correction factors in reference dose measurements in single static and dynamic IMRT fields was studied. The results show that, for thimble-type ionization chambers the correction factor in a single, realistic dynamic IMRT field can be of the order of 10% or more. We therefore propose that for accurate reference dosimetry of complete n-beam IMRT deliveries, ionization chamber fluence perturbation correction factors must explicitly be taken into account.

Total Ionizing Dose Effects in Bipolar and BiCMOS Devices

NASA Technical Reports Server (NTRS)

Chavez, Rosa M.; Rax, Bernard G.; Scheick, Leif Z.; Johnston, Allan H.

2005-01-01

This paper describes total ionizing dose (TID) test results performed at JPL. Bipolar and BiCMOS device samples were tested exhibiting significant degradation and failures at different irradiation levels. Linear technology which is susceptible to low-dose dependency (ELDRS) exhibited greater damage for devices tested under zero bias condition.

SU-G-IeP2-11: Measurement of Equilibrium Doses in Computed Tomography: Comparative Study of Ionization and Solid-State Dosimeters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsubara, K; Kobayashi, A; Koshida, K

Purpose: This study aimed to compare equilibrium doses in computed tomography (CT) obtained from ionization and solid-state dosimeters based on the approach presented in the American Association of Physicists in Medicine Report No. 111. The equilibrium doses were also compared with the CT dose index (CTDI) using a 10-cm pencil-type ionization chamber. Methods: A 0.6-cm{sup 3} ionization chamber (10X6-0.6CT) and a solid-state detector (CT Dose Profiler [CTDP]) were calibrated using 80–130 kVp X-ray beams (44.5–55.8 keV of effective energy) from a radiography X-ray machine against a reference ionization dosimeter. Three 16- or 32-cm diameter polymethyl methacrylate (PMMA) phantoms were assembledmore » consecutively on the CT table to obtain equilibrium doses. The 10X6-0.6CT and CTDP were each placed at the center and peripheral holes (12, 3, 6, and 9 o’clock) of the z-center. Central and mean peripheral equilibrium doses were obtained by scanning with longitudinal translation for a length less than the entire phantom length. CTDIs were also obtained with a 10-cm pencil-type ionization chamber (10X6-0.6CT) by scanning a 16- or 32-cm diameter PMMA phantom with one rotation of the X-ray tube. Results: The difference of calibration coefficients between 80 and 130 kVp was 21.1% for the CTDP and 0.7% for the 10X6-0.6CT. The equilibrium doses were higher than the CTDI. Especially at the peripheral positions and 80 kVp, the 10X6-0.6CT showed higher equilibrium doses than CTDP. However, the relation between the equilibrium dose for the 10X6-0.6CT and the CTDP differed depending on the phantom size, scanner type, measurement position, and selected acquisition parameters. Conclusion: The use of a 10-cm pencil-type ionization chamber causes underestimation of the equilibrium dose. The CTDP has a higher energy dependency than the 10X6-0.6CT. The obtained equilibrium doses are different between the 10X6-0.6CT and the CTDP depending on various conditions. This study was supported by JSPS KAKENHI Grant Number 15K09887.« less

SU-F-T-32: Evaluation of the Performance of a Multiple-Array-Diode Detector for Quality Assurance Tests in High-Dose-Rate Brachytherapy with Ir-192 Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harpool, K; De La Fuente Herman, T; Ahmad, S

Purpose: To evaluate the performance of a two-dimensional (2D) array-diode- detector for geometric and dosimetric quality assurance (QA) tests of high-dose-rate (HDR) brachytherapy with an Ir-192-source. Methods: A phantom setup was designed that encapsulated a two-dimensional (2D) array-diode-detector (MapCheck2) and a catheter for the HDR brachytherapy Ir-192 source. This setup was used to perform both geometric and dosimetric quality assurance for the HDR-Ir192 source. The geometric tests included: (a) measurement of the position of the source and (b) spacing between different dwell positions. The dosimteric tests include: (a) linearity of output with time, (b) end effect and (c) relative dosemore » verification. The 2D-dose distribution measured with MapCheck2 was used to perform the previous tests. The results of MapCheck2 were compared with the corresponding quality assurance testes performed with Gafchromic-film and well-ionization-chamber. Results: The position of the source and the spacing between different dwell-positions were reproducible within 1 mm accuracy by measuring the position of maximal dose using MapCheck2 in contrast to the film which showed a blurred image of the dwell positions due to limited film sensitivity to irradiation. The linearity of the dose with dwell times measured from MapCheck2 was superior to the linearity measured with ionization chamber due to higher signal-to-noise ratio of the diode readings. MapCheck2 provided more accurate measurement of the end effect with uncertainty < 1.5% in comparison with the ionization chamber uncertainty of 3%. Although MapCheck2 did not provide absolute calibration dosimeter for the activity of the source, it provided accurate tool for relative dose verification in HDR-brachytherapy. Conclusion: The 2D-array-diode-detector provides a practical, compact and accurate tool to perform quality assurance for HDR-brachytherapy with an Ir-192 source. The diodes in MapCheck2 have high radiation sensitivity and linearity that is superior to Gafchromic-films and ionization chamber used for geometric and dosimetric QA in HDR-brachytherapy, respectively.« less

SU-E-I-45: Measurement of CT Dose to An HDPE Phantom Using Calorimetry: A Feasibility Study.

PubMed

Chen-Mayer, H; Tosh, R; Bateman, F; Zimmerman, B

2012-06-01

Radiation dose in CT is traditionally evaluated using an ionization chamber calibrated in terms of air kerma in a phantom of specific dimensions. The radiation absorbed dose, J/kg, can also be realized directly by measuring the temperature rise in the medium. We investigate using this primary method to determine the CT dose at a point (a few mm), using the recently proposed (APMM TG220) high density polyethylene (HDPE) phantom as a medium. The calorimeter detection scheme is adapted from the second generation NIST water calorimeter using sensitive thermistors in a Wheatstone bridge powered by a lock-in amplifier. The temperature sensitivity is about 3 microK. The expected temperature rise in PE is about 0.6 mK per Gy. The thermistor sensors were placed inside a 26 cm dia. × 10 cm HDPE phantom. Two preliminary tests were made: at a linear accelerator with a 6 MV photon beam, and at a 16-slice CT scanner with a 120 kV beam, each with the thermal sensor and with a calibrated ionization chamber. The 6 MV photon beam with 10 on/off cycles at 60 s each yielded the (uncorrected) run-to-run average dose of 3.06 Gy per cycle (sdm 0.3%), about 8% higher than the Result from the ionization chamber (calibrated in terms of absorbed to water). The CT measurements were also made in the middle section of the TG200 30 cm phantom. Twenty consecutive axial scans at 250 mA, which delivers a nominal accumulated dose (CTDIvol) of 705 mGy in 50 s at three axial and three radial locations were measured. The accumulated dose measured by the ionization chamber at the center of the smaller phantom was 347 mGy. The calorimeter data show qualitative tracking of the chamber measurements. Detailed thermal and electrical analysis of the system are planned to obtain quantitative results. © 2012 American Association of Physicists in Medicine.

Identifying the health risks from very low-dose sparsely ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dreyer, N.A.; Friedlander, E.

1982-01-01

The health risks from low-dose sparsely ionizing (low-LET) radiation have been the subject of continued debate. At present, quantitative estimates of risk are extremely uncertain due to the controversy surrounding both the dosimetry for A-bomb survivor data and the choice of mathematical models for extrapolating risk from high to low doses. Nevertheless, much can be learned about the nature of the health risks by reviewing the epidemiologic literature. We present a summary of diseases which have been associated with low-LET radiation (<1000 rad) in at least two independent studies, according to the mean cumulative organ dose at which the diseasemore » was observed. At organ doses of less than or equal to50 rad, the only diseases that have been reported consistently are thyroid cancer, salivary gland tumors, and leukemia. The first two diseases were observed in association with x-ray epilation of the scalp for tinea capitis, a therapy which is no longer employed. On the other hand, leukemia has been observed repeatedly to occur at cumulative doses of greater than or equal to30 rad low-LET radiation.« less

Compendium of Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Boutte, Alvin J.; Chen, Dakai; Pellish, Jonathan A.; Ladbury, Raymond L.; Casey, Megan C.; Campola, Michael J.; Wilcox, Edward P.; Obryan, Martha V.; LaBel, Kenneth A.;

A study of the effects of therapeutic doses of ionizing radiation in vitro on Lactobacillus isolates originating from the vagina - a pilot study.

PubMed

Gosiewski, Tomasz; Mróz, Tomasz; Ochońska, Dorota; Pabian, Wojciech; Bulanda, Malgorzata; Brzychczy-Wloch, Monika

2016-05-31

Ionizing radiation is used as a therapeutic option in the treatment of certain neoplastic lesions located, among others, in the pelvic region. The therapeutic doses of radiation employed often result in adverse effects manifesting themselves primarily in the form of genital tract infections in patients or diarrhea. The data available in the literature indicate disorders in the microbial ecosystem caused by ionizing radiation, which leads to the problems mentioned above. In the present study, we examined the influence of ionizing radiation on 52 selected strains of bacteria: Lactobacillus crispatus, L. fermentum, L. plantarum, L. reuteri, L. acidophilus L. amylovorus, L. casei, L. helveticus, L. paracasei, L. rhamnosus, L. salivarius and L. gasseri. This collection of Lactobacillus bacteria isolates of various species, obtained from the genital tract and gastrointestinal tract of healthy women, was tested for resistance to therapeutic doses of ionizing radiation. The species studied, were isolated from the genital tract (n = 30) and from the anus (n = 22) of healthy pregnant women. Three doses of 3 Gy (fractionated dose) and 50 Gy (total dose of the whole radiotherapy cycle) were applied. The greatest differences in survival of the tested strains in comparison to the control group (not subjected to radiation) were observed at the dose of 50 Gy. However, the results were not statistically significant. Survival decrease to zero was not demonstrated for any of the tested strains. Therapeutic doses of radiation do not affect the Lactobacillus bacteria significantly.

Dosimetry of Al2O3 optically stimulated luminescent dosimeter at high energy photons and electrons

NASA Astrophysics Data System (ADS)

Yusof, M. F. Mohd; Joohari, N. A.; Abdullah, R.; Shukor, N. S. Abd; Kadir, A. B. Abd; Isa, N. Mohd

2018-01-01

The linearity of Al2O3 OSL dosimeters (OSLD) were evaluated for dosimetry works in clinical photons and electrons. The measurements were made at a reference depth of Zref according to IAEA TRS 398:2000 codes of practice at 6 and 10 MV photons and 6 and 9 MeV electrons. The measured dose was compared to the thermoluminescence dosimeters (TLD) and ionization chamber commonly used for dosimetry works for higher energy photons and electrons. The results showed that the measured dose in OSL dosimeters were in good agreement with the reported by the ionization chamber in both high energy photons and electrons. A reproducibility test also reported excellent consistency of readings with the OSL at similar energy levels. The overall results confirmed the suitability of OSL dosimeters for dosimetry works involving high energy photons and electrons in radiotherapy.

Assessment of the Technologies for Molecular Biodosimetry for Human Low-Dose Radiation Exposure Symposium: Agenda and Abstracts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, Matthew A.; Ramakrishnan, Narayani

In the event of a radiological accident, the rapid evaluation of the individual absorbed dose is paramount to discriminate those individuals who must receive medical attention. New research with genomic- and proteomic-wide tools is showing that within minutes to hours after exposure to ionizing radiation the cellular machinery is modified. For example: large-scale changes occur in the gene expression profiles involving a broad variety of cellular pathways after a wide range of both low dose (<10 cGy) and high dose (>10 cGy) ionizing radiation exposures. Symposium 12 was organized to address a wide range of biological effects using the latestmore » technologies. To address current models following ionizing radiation exposure, methods in biodosimetry and dose effects the symposia featured a general overview titled “Model Systems and Current Approaches in Biodosimetry” by Matthew A. Coleman, from Lawrence Livermore National Laboratory and a talk entitled “Brief Overview of Biodosimetry Projects in the NIH Rad/Nuc Program” by Dr. Narayani Ramakrishnan, National Institute of Allergy and Infectious Diseases. These two talk set the tone for issues in data and model integration as well as addressing the national need for robust technologies for biological dosimetry. The report continues with more description of the presentations, along with the agenda and abstracts of the papers presented.« less

Enhanced Low Dose Rate Effects in Bipolar Circuits: A New Hardness Assurance Problem for NASA

NASA Technical Reports Server (NTRS)

Johnston, A.; Barnes, C.

1995-01-01

Many bipolar integrated circuits are much more susceptible to ionizing radiation at low dose rates than they are at high dose rates typically used for radiation parts testing. Since the low dose rate is equivalent to that seen in space, the standard lab test no longer can be considered conservative and has caused the Air Force to issue an alert. Although a reliable radiation hardness assurance test has not yet been designed, possible mechanisms for low dose rate enhancement and hardness assurance tests are discussed.

Radiation response of industrial materials: Dose-rate and morphology implications

NASA Astrophysics Data System (ADS)

Berejka, Anthony J.

2007-08-01

Industrial uses of ionizing radiation mostly rely upon high current, high dose-rate (100 kGy/s) electron beam (EB) accelerators. To a lesser extent, industry uses low dose-rate (2.8 × 10-3 kGy/s) radioactive Cobalt-60 as a gamma source, generally for some rather specific purposes, as medical device sterilization and the treatment of food and foodstuffs. There are nearly nine times as many (∼1400) high current EB units in commercial operation than gamma sources (∼160). However, gamma sources can be easily scaled-down so that much research on materials effects is conducted using gamma radiation. Likewise, laboratories are more likely to have very low beam current and consequently low dose-rate accelerators such as Van de Graaff generators and linear accelerators. With the advent of very high current EB accelerators, X-ray processing has become an industrially viable option. With X-rays from high power sources, dose-rates can be modulated based upon accelerator power and the attenuation of the X-ray by the distance of the material from the X-ray target. Dose and dose-rate dependence has been found to be of consequence in several commercial applications which can employ the use of ionizing radiation. The combination of dose and dose-rate dependence of the polymerization and crosslinking of wood impregnants and of fiber composite matrix materials can yield more economically viable results which have promising commercial potential. Monomer and oligomer structure also play an important role in attaining these desirable results. The influence of morphology is shown on the radiation response of olefin polymers, such as ethylene, propylene and isobutylene polymers and their copolymers. Both controlled morphology and controlled dose-rate have commercial consequences. These are also impacted both by the adroit selection of materials and through the possible use of X-ray processing.

Low-dose ionizing irradiation triggers a 53BP1 response to DNA double strand breaks in mouse spermatogonial stem cells.

PubMed

Le, Wei; Qi, Lixin; Li, Jiaxuan; Wu, DengIong; Xu, Jun; Zhang, Jinfu

2016-01-01

The present study aims to examine the effect of low-dose ionizing irradiation on DNA double strand breaks (DSB) in mouse spermatogonial stem cells (SSCs) and reveal the underlying pathways for the DNA repair for DSB in SSCs. Eighteen one-month-old mice were divided into 6 groups and sacrificed separately at 45 minutes, 2 hours, 24 hours, 48 hours, and 72 hours after 0.1Gy X-ray irradiation (mice without receiving ionizing irradiation served as control). After perfusion fixation, testes were removed, sectioned, and followed by staining of γH2AX, 53BP1, Caspase 3, and promyelocytic leukemia zinc-finger (PLZF) for analysis among the different groups. The staining was observed by immunofluorescence visualized by confocal laser scanning. After low-dose irradiation, only 53BP1, but not Caspase3 or γH2AX was upregulated in PLZF positive SSCs within 45 minutes. The expression level of 53BP1 gradually decreased 24 hours after irradiation. Moreover, low-dose irradiation had no effect on the cell number and apoptotic status of SSCs. However other spermatogenic cells highly expressed γH2AX shortly after irradiation which was dramatically reduced following the events of DNA repair. It appears that low-dose ionizing irradiation may cause the DNA DSB of mouse spermatogenic cells. 53BP1, but not γH2AX, is involved in the DNA repair for DSB in SSCs. Our data indicates that 53BP1 plays an important role in the pathophysiological repair of DNA DSB in SSCs. This may open a new avenue to understanding the mechanisms of DNA repair of SSCs and male infertility.

Total Ionizing Dose and Displacement Damage Compendium of Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Chen, Dakai; Oldham, Timothy R.; Sanders, Anthony B.; Kim, Hak S.; Campola, Michael J.; Buchner, Stephen P.; LaBel, Kenneth A.; Marshall, Cheryl J.; Pellish, Jonathan A.;

Low dose or low dose rate ionizing radiation-induced health effect in the human.

PubMed

Tang, Feng Ru; Loganovsky, Konstantin

2018-06-05

The extensive literature review on human epidemiological studies suggests that low dose ionizing radiation (LDIR) (≤100 mSv) or low dose rate ionizing radiation (LDRIR) (<6mSv/H) exposure could induce either negative or positive health effects. These changes may depend on genetic background, age (prenatal day for embryo), sex, nature of radiation exposure, i.e., acute or chronic irradiation, radiation sources (such as atomic bomb attack, fallout from nuclear weapon test, nuclear power plant accidents, 60 Co-contaminated building, space radiation, high background radiation, medical examinations or procedures) and radionuclide components and human epidemiological experimental designs. Epidemiological and clinical studies show that LDIR or LDRIR exposure may induce cancer, congenital abnormalities, cardiovascular and cerebrovascular diseases, cognitive and other neuropsychiatric disorders, cataracts and other eye and somatic pathology (endocrine, bronchopulmonary, digestive, etc). LDIR or LDRIR exposure may also reduce mutation and cancer mortality rates. So far, the mechanisms of LDIR- or LDRIR -induced health effect are poorly understood. Further extensive studies are still needed to clarify under what circumstances, LDIR or LDRIR exposure may induce positive or negative effects, which may facilitate development of new therapeutic approaches to prevent or treat the radiation-induced human diseases or enhance radiation-induced positive health effect. Copyright © 2018 Elsevier Ltd. All rights reserved.

Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers

NASA Astrophysics Data System (ADS)

Lye, J. E.; Harty, P. D.; Butler, D. J.; Crosbie, J. C.; Livingstone, J.; Poole, C. M.; Ramanathan, G.; Wright, T.; Stevenson, A. W.

2016-06-01

The absolute dose delivered to a dynamically scanned sample in the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter anticipated to be established as a primary standard for synchrotron dosimetry. The calorimetry was compared to measurements using a free-air chamber (FAC), a PTW 31 014 Pinpoint ionization chamber, and a PTW 34 001 Roos ionization chamber. The IMBL beam height is limited to approximately 2 mm. To produce clinically useful beams of a few centimetres the beam must be scanned in the vertical direction. In practice it is the patient/detector that is scanned and the scanning velocity defines the dose that is delivered. The calorimeter, FAC, and Roos chamber measure the dose area product which is then converted to central axis dose with the scanned beam area derived from Monte Carlo (MC) simulations and film measurements. The Pinpoint chamber measures the central axis dose directly and does not require beam area measurements. The calorimeter and FAC measure dose from first principles. The calorimetry requires conversion of the measured absorbed dose to graphite to absorbed dose to water using MC calculations with the EGSnrc code. Air kerma measurements from the free air chamber were converted to absorbed dose to water using the AAPM TG-61 protocol. The two ionization chambers are secondary standards requiring calibration with kilovoltage x-ray tubes. The Roos and Pinpoint chambers were calibrated against the Australian primary standard for air kerma at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Agreement of order 2% or better was obtained between the calorimetry and ionization chambers. The FAC measured a dose 3-5% higher than the calorimetry, within the stated uncertainties.

Effects of high energy radiation on the mechanical properties of epoxy/graphite fiber reinforced composites

NASA Technical Reports Server (NTRS)

Fornes, R. E.; Gilbert, R. D.; Memory, J. D.

1986-01-01

The epoxy resin system formed by tetraglycidyl 4,4'-diamino diphenyl methane (TGDDM) and 4,4'-diamino diphenyl sulfone (DDS) was characterized by dynamic mechanical analysis and differential scanning calorimetry. Dynamic mechanical properties of graphite fiber epoxy composite specimens formulated with two different adhesive systems (NARMCO 5208, NARMCO 5209) were determined. The specimens were exposed to varying dose levels of ionizing radiation (0.5 MeV electrons) with a maximum absorbed dose of 10,000 Mrads. Following irradiation, property measurements were made to assess the influence of radiation on the epoxy and composite specimens. The results established that ionizing radiation has a limited effect on the properties of epoxy and composite specimens.

Recent Total Ionizing Dose and Displacement Damage Compendium of Candidate Electronics for NASA Space Systems

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Boutte, Alvin J.; Campola, Michael J.; Carts, Martin A.; Casey, Megan C.; Chen, Dakai; LaBel, Kenneth A.; Ladbury, Raymond L.; Lauenstein, Jean-Marie; Marshall, Cheryl J.;

GDF-15 gene expression alterations in human lymphoblastoid cells and peripheral blood lymphocytes following exposure to ionizing radiation

PubMed Central

Li, Shuang; Zhang, Qing-Zhao; Zhang, De-Qin; Feng, Jiang-Bin; Luo, Qun; Lu, Xue; Wang, Xin-Ru; Li, Kun-Peng; Chen, De-Qing; Mu, Xiao-Feng; Gao, Ling; Liu, Qing-Jie

2017-01-01

The identification of rapid, sensitive and high-throughput biomarkers is imperative in order to identify individuals harmed by radiation accidents, and accurately evaluate the absorbed doses of radiation. DNA microarrays have previously been used to evaluate the alterations in growth/differentiation factor 15 (GDF15) gene expression in AHH-1 human lymphoblastoid cells, following exposure to γ-rays. The present study aimed to characterize the relationship between the dose of ionizing radiation and the produced effects in GDF-15 gene expression in AHH-1 cells and human peripheral blood lymphocytes (HPBLs). GDF-15 mRNA and protein expression levels following exposure to γ-rays and neutron radiation were assessed by reverse transcription-quantitative polymerase chain reaction and western blot analysis in AHH-1 cells. In addition, alterations in GDF-15 gene expression in HPBLs following ex vivo irradiation were evaluated. The present results demonstrated that GDF-15 mRNA and protein expression levels in AHH-1 cells were significantly upregulated following exposure to γ-ray doses ranging between 1 and 10 Gy, regardless of the dose rate. A total of 48 h following exposure to neutron radiation, a dose-response relationship was identified in AHH-1 cells at γ-ray doses between 0.4 and 1.6 Gy. GDF-15 mRNA levels in HPBLs were significantly upregulated following exposure to γ-ray doses between 1 and 8 Gy, within 4–48 h following irradiation. These results suggested that significant time- and dose-dependent alterations in GDF-15 mRNA and protein expression occur in AHH-1 cells and HPBLs in the early phases following exposure to ionizing radiation. In conclusion, alterations in GDF-15 gene expression may have potential as a biomarker to evaluate radiation exposure. PMID:28440431

A Double-Blind Placebo-Controlled Crossover Trial of Intravenous Magnesium Sulfate for Foscarnet-Induced Ionized Hypocalcemia and Hypomagnesemia in Patients with AIDS and Cytomegalovirus Infection

PubMed Central

Huycke, Mark M.; Naguib, M. Tarek; Stroemmel, Mathias M.; Blick, Kenneth; Monti, Katherine; Martin-Munley, Sarah; Kaufman, Chris

2000-01-01

Foscarnet (trisodium phosphonoformate hexahydrate) is an antiviral agent used to treat cytomegalovirus disease in immunocompromised patients. One common side effect is acute ionized hypocalcemia and hypomagnesemia following intravenous administration. Foscarnet-induced ionized hypomagnesemia might contribute to ionized hypocalcemia by impairing excretion of preformed parathyroid hormone (PTH) or by producing target organ resistance. Prevention of ionized hypomagnesemia following foscarnet administration could blunt the development of ionized hypocalcemia. To determine whether intravenous magnesium ameliorates the decline in ionized calcium and/or magnesium following foscarnet infusions, MgSO4 at doses of 1, 2, and 3 g was administered in a double-blind, placebo-controlled, randomized, crossover trial to 12 patients with AIDS and cytomegalovirus disease. Overall, increasing doses of MgSO4 reduced or eliminated foscarnet-induced acute ionized hypomagnesemia. Supplementation, however, had no discernible effect on foscarnet-induced ionized hypocalcemia despite significant increases in serum PTH levels. No dose-related, clinically significant adverse events were found, suggesting that intravenous supplementation with up to 3 g of MgSO4 was safe in this chronically ill population. Since parenteral MgSO4 did not alter foscarnet-induced ionized hypocalcemia or symptoms associated with foscarnet, routine intravenous supplementation for patients with normal serum magnesium levels is not recommended during treatment with foscarnet. PMID:10898688

Reducing ionizing radiation doses during cardiac interventions in pregnant women.

PubMed

Orchard, Elizabeth; Dix, Sarah; Wilson, Neil; Mackillop, Lucy; Ormerod, Oliver

2012-09-01

There is concern over ionizing radiation exposure in women who are pregnant or of child-bearing age. Due to the increasing prevalence of congenital and acquired heart disease, the number of women who require cardiac interventions during pregnancy has increased. We have developed protocols for cardiac interventions in pregnant women and women of child-bearing age, aimed at substantially reducing both fluoroscopy duration and radiation doses. Over five years, we performed cardiac interventions on 15 pregnant women, nine postpartum women and four as part of prepregnancy assessment. Fluoroscopy times were minimized by simultaneous use of intracardiac echocardiography, and by using very low frame rates (2/second) during fluoroscopy. The procedures most commonly undertaken were closure of atrial septal defect (ASD) or patent foramen ovale (PFO) in 16 women, coronary angiograms in seven, right and left heart catheters in three and two stent placements. The mean screening time for all patients was 2.38 minutes (range 0.48-13.7), the median radiation dose was 66 (8.9-1501) Gy/cm(2). The median radiation dose to uterus was 1.92 (0.59-5.47) μGy, and the patient estimated dose was 0.24 (0.095-0.80) mSv. Ionizing radiation can be used safely in the management of severe cardiac structural disease in pregnancy, with very low ionizing radiation dose to the mother and extremely low exposure to the fetus. With experience, ionizing radiation doses at our institution have been reduced.

The Effect of High-Dose Ionizing Radiation on the Isolated Photobiont of the Astrobiological Model Lichen Circinaria gyrosa

NASA Astrophysics Data System (ADS)

Meeßen, Joachim; Backhaus, Theresa; Brandt, Annette; Raguse, Marina; Böttger, Ute; de Vera, Jean-Pierre; de la Torre, Rosa

2017-02-01

Lichen symbioses between fungi and algae represent successful life strategies to colonize the most extreme terrestrial habitats. Consequently, space exposure and simulation experiments have demonstrated lichens' high capacity for survival, and thus, they have become models in astrobiological research with which to discern the limits and limitations of terrestrial life. In a series of ground-based irradiation experiments, the STARLIFE campaign investigated the resistance of astrobiological model organisms to galactic cosmic radiation, which is one of the lethal stressors of extraterrestrial environments. Since previous studies have identified that the alga is the more sensitive lichen symbiont, we chose the isolated photobiont Trebouxia sp. of the astrobiological model Circinaria gyrosa as a subject in the campaign. Therein, γ radiation was used to exemplify the deleterious effects of low linear energy transfer (LET) ionizing radiation at extremely high doses up to 113 kGy in the context of astrobiology. The effects were analyzed by chlorophyll a fluorescence of photosystem II (PSII), cultivation assays, live/dead staining and confocal laser scanning microscopy (CLSM), and Raman laser spectroscopy (RLS). The results demonstrate dose-dependent impairment of photosynthesis, the cessation of cell proliferation, cellular damage, a decrease in metabolic activity, and degradation of photosynthetic pigments. While previous investigations on other extraterrestrial stressors have demonstrated a high potential of resistance, results of this study reveal the limits of photobiont resistance to ionizing radiation and characterize γ radiation-induced damages. This study also supports parallel STARLIFE studies on the lichens Circinaria gyrosa and Xanthoria elegans, both of which harbor a Trebouxia sp. photobiont.

Advanced p-MOSFET Ionizing-Radiation Dosimeter

NASA Technical Reports Server (NTRS)

Buehler, Martin G.; Blaes, Brent R.

1994-01-01

Circuit measures total dose of ionizing radiation in terms of shift in threshold gate voltage of doped-channel metal oxide/semiconductor field-effect transistor (p-MOSFET). Drain current set at temperature-independent point to increase accuracy in determination of radiation dose.

Compendium of Current Total Ionizing Dose Results and Displacement Damage Results for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; O'Bryan, Martha V.; Buchner, Stephen P.; Poivey, Christian; Ladbury, Ray L.; LaBel, Kenneth A.

2007-01-01

Sensitivity of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear bipolar devices, and hybrid devices.

A Biodosimeter for Multiparametric Determination of Radiation Dose, Radiation Quality, and Radiation Risk

NASA Technical Reports Server (NTRS)

Richmond, Robert; Cruz, Angela; Jansen, Heather; Bors, Karen

2003-01-01

Predicting risk of human cancer following exposure of an individual or a population to ionizing radiation is challenging. To an approximation, this is because uncertainties of uniform absorption of dose and the uniform processing of dose-related damage at the cellular level within a complex set of biological variables degrade the confidence of predicting the delayed expression of cancer as a relatively rare event. Cellular biodosimeters that simultaneously report: 1) the quantity of absorbed dose after exposure to ionizing radiation, 2) the quality of radiation delivering that dose, and 3) the risk of developing cancer by the cells absorbing that dose would therefore be useful. An approach to such a multiparametric biodosimeter will be reported. This is the demonstration of a dose responsive field effect of enhanced expression of keratin 18 (K18) in cultures of human mammary epithelial cells irradiated with cesium-1 37 gamma-rays. Dose response of enhanced K18 expression was experimentally extended over a range of 30 to 90 cGy for cells evaluated at mid-log phase. K18 has been reported to be a marker for tumor staging and for apoptosis, and thereby serves as an example of a potential marker for cancer risk, where the reality of such predictive value would require additional experimental development. Since observed radiogenic increase in expression of K18 is a field effect, ie., chronically present in all cells of the irradiated population, it may be hypothesized that K18 expression in specific cells absorbing particulate irradiation, such as the high-LET-producing atomic nuclei of space radiation, will report on both the single-cell distributions of those particles amongst cells within the exposed population, and that the relatively high dose per cell delivered by densely ionizing tracks of those intersecting particles will lead to cell-specific high-expression levels of K18, thereby providing analytical end points that may be used to resolve both the quantity and the quality of the radiation dose absorbed by individual cells. The principal value of this reported potential multiparametric cellular biodosimeter is suggested to be that it justifies a search for similar but more robust radiogenic assays. That is, K18 is only one radiation dose-sensitive expressed protein, whereas analytical techniques of genomics and proteomics can be used to simultaneously analyze multiple gene and protein expressions resulting from radiation-dose absorption. The potential usefulness of multiparametric cellular biodosimeters will be best realized from quantitatively profiling these multiple markers using these modern techniques.

Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanyi, James A.; Nitzling, Kevin D.; Lodwick, Camille J.

2011-02-15

Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation {+-}0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibilitymore » of the system was {+-}0.55% for dose fractions of {approx}100 cGy. Energy dependence was within {+-}1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R{sup 2}=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within {+-}0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.« less

Comparison of the ionizing radiation effects on cochineal, annatto and turmeric natural dyes

NASA Astrophysics Data System (ADS)

Cosentino, Helio M.; Takinami, Patricia Y. I.; del Mastro, Nelida L.

2016-07-01

As studies on radiation stability of food dyes are scarce, commercially important natural food grade dyes were evaluated in terms of their sensitivity against gamma ionizing radiation. Cochineal, annatto and turmeric dyes with suitable concentrations were subjected to increasing doses up to 32 kGy and analyzed by spectrophotometry and capillary electrophoresis. The results showed different pattern of absorbance versus absorbed dose for the three systems. Carmine, the glucosidal coloring matter from the scale insect Coccus cacti L., Homoptera (cochineal) remained almost unaffected by radiation up to doses of about 32 kGy (absorbance at 494 nm). Meanwhile, at that dose, a plant-derived product annatto or urucum (Bixa orellana L.) tincture presented a nearly 58% reduction in color intensity. Tincture of curcumin (diferuloylmethane) the active ingredient in the eastern spice turmeric (Curcuma longa) showed to be highly sensitive to radiation when diluted. These data shall be taken in account whenever food products containing these food colors were going to undergo radiation processing.

Quantifying Cancer Risk from Radiation.

PubMed

Keil, Alexander P; Richardson, David B

2017-12-06

Complex statistical models fitted to data from studies of atomic bomb survivors are used to estimate the human health effects of ionizing radiation exposures. We describe and illustrate an approach to estimate population risks from ionizing radiation exposure that relaxes many assumptions about radiation-related mortality. The approach draws on developments in methods for causal inference. The results offer a different way to quantify radiation's effects and show that conventional estimates of the population burden of excess cancer at high radiation doses are driven strongly by projecting outside the range of current data. Summary results obtained using the proposed approach are similar in magnitude to those obtained using conventional methods, although estimates of radiation-related excess cancers differ for many age, sex, and dose groups. At low doses relevant to typical exposures, the strength of evidence in data is surprisingly weak. Statements regarding human health effects at low doses rely strongly on the use of modeling assumptions. © 2017 Society for Risk Analysis.

James V. Neel and Yuri E. Dubrova: Cold War debates and the genetic effects of low-dose radiation.

PubMed

Goldstein, Donna M; Stawkowski, Magdalena E

2015-01-01

This article traces disagreements about the genetic effects of low-dose radiation exposure as waged by James Neel (1915-2000), a central figure in radiation studies of Japanese populations after World War II, and Yuri Dubrova (1955-), who analyzed the 1986 Chernobyl nuclear power plant accident. In a 1996 article in Nature, Dubrova reported a statistically significant increase in the minisatellite (junk) DNA mutation rate in the children of parents who received a high dose of radiation from the Chernobyl accident, contradicting studies that found no significant inherited genetic effects among offspring of Japanese A-bomb survivors. Neel's subsequent defense of his large-scale longitudinal studies of the genetic effects of ionizing radiation consolidated current scientific understandings of low-dose ionizing radiation. The article seeks to explain how the Hiroshima/Nagasaki data remain hegemonic in radiation studies, contextualizing the debate with attention to the perceived inferiority of Soviet genetic science during the Cold War.

Whole-body γ-irradiation decelerates rat hepatocyte polyploidization.

PubMed

Ikhtiar, Adnan M

2015-07-01

To characterize hepatocyte polyploidization induced by intermediate dose of γ-ray. Male Wistar strain rats were whole-body irradiated (WBI) with 2 Gy of γ-ray at the age of 1 month, and 5-6 rats were sacrificed monthly at 0-25 months after irradiation. The nuclear DNA content of individual hepatocytes was measured by flow cytometry, then hepatocytes were classified into various ploidy classes. Survival percentage, after exposure up to the end of the study, did not indicate any differences between the irradiated groups and controls. The degree of polyploidization in hepatocytes of irradiated rats, was significantly lower than that for the control after 1 month of exposure, and it continued to be lower after up to 8 months. Thereafter, the degree of polyploidization in the irradiated group slowly returned to the control level when the irradiated rats reached the age of 10 months. Intermediate dose of ionizing radiation, in contrast to high doses, decelerate hepatocyte polyploidization, which may coincides with the hypothesis of the beneficial effects of low doses of ionizing radiation.

Update on the biological effects of ionizing radiation, relative dose factors and radiation hygiene.

PubMed

White, Stuart C; Mallya, S M

2012-03-01

Diagnostic imaging is an indispensable part of contemporary medical and dental practice. Over the last few decades there has been a dramatic increase in the use of ionizing radiation for diagnostic imaging. The carcinogenic effects of high-dose exposure are well known. Does diagnostic radiation rarely cause cancer? We don't know but we should act as if it does. Accordingly, dentists should select patients wisely - only make radiographs when there is patient-specific reason to believe there is a reasonable expectation the radiograph will offer unique information influencing diagnosis or treatment. Low-dose examinations should be made: intraoral imaging - use fast film or digital sensors, thyroid collars, rectangular collimation; panoramic and lateral cephalometric imaging - use digital systems or rare-earth film screen combinations; and cone beam computed tomography - use low-dose machines, restrict field size to region of interest, reduce mA and length of exposure arc as appropriate. © 2012 Australian Dental Association.

Small total dose measurement system for SDS-1

NASA Astrophysics Data System (ADS)

Kimoto, Yugo; Satoh, Yohei; Tachihara, Hiroshi

2009-11-01

The Japanese Aerospace Exploration Agency (JAXA) uses monitors on board satellites to measure and record in-flight data on ionization effects in space. A compact, total dose measurement system for the small satellite (SDS-1) was developed based on the previous system for measuring total ionizing dose effects. Especially, the sensor for SDS-1 is quite smaller than the sensor for SOHLA-1, which is presented in the last year. The sensor is 8 mm wide×3 mm high×19 mm long and weighs approximately 4 g with 500 mm its wire harness. Eight pin LCC RADFET and temperature sensor are arranged on it. Seven sensors are arranged on some components inside the SDS-1. One of the sensors is arranged on a printed board in advanced microprocessing in-ORBIT experiment equipment (AMI). The AMI demonstrate 320 MIPS microprocessor and DC-DC converter for space. The absorbed dose at the points where the sensors are arranged was evaluated before flight and will be compared with resulting flight data.

Assessment of ionization chamber correction factors in photon beams using a time saving strategy with PENELOPE code.

PubMed

Reis, C Q M; Nicolucci, P

2016-02-01

The purpose of this study was to investigate Monte Carlo-based perturbation and beam quality correction factors for ionization chambers in photon beams using a saving time strategy with PENELOPE code. Simulations for calculating absorbed doses to water using full spectra of photon beams impinging the whole water phantom and those using a phase-space file previously stored around the point of interest were performed and compared. The widely used NE2571 ionization chamber was modeled with PENELOPE using data from the literature in order to calculate absorbed doses to the air cavity of the chamber. Absorbed doses to water at reference depth were also calculated for providing the perturbation and beam quality correction factors for that chamber in high energy photon beams. Results obtained in this study show that simulations with phase-space files appropriately stored can be up to ten times shorter than using a full spectrum of photon beams in the input-file. Values of kQ and its components for the NE2571 ionization chamber showed good agreement with published values in the literature and are provided with typical statistical uncertainties of 0.2%. Comparisons to kQ values published in current dosimetry protocols such as the AAPM TG-51 and IAEA TRS-398 showed maximum percentage differences of 0.1% and 0.6% respectively. The proposed strategy presented a significant efficiency gain and can be applied for a variety of ionization chambers and clinical photon beams. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Radiation Response of Emerging High Gain, Low Noise Detectors

NASA Technical Reports Server (NTRS)

Becker, Heidi N.; Farr, William H; Zhu, David Q.

2007-01-01

Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

Repair-dependent cell radiation survival and transformation: an integrated theory.

PubMed

Sutherland, John C

2014-09-07

The repair-dependent model of cell radiation survival is extended to include radiation-induced transformations. The probability of transformation is presumed to scale with the number of potentially lethal damages that are repaired in a surviving cell or the interactions of such damages. The theory predicts that at doses corresponding to high survival, the transformation frequency is the sum of simple polynomial functions of dose; linear, quadratic, etc, essentially as described in widely used linear-quadratic expressions. At high doses, corresponding to low survival, the ratio of transformed to surviving cells asymptotically approaches an upper limit. The low dose fundamental- and high dose plateau domains are separated by a downwardly concave transition region. Published transformation data for mammalian cells show the high-dose plateaus predicted by the repair-dependent model for both ultraviolet and ionizing radiation. For the neoplastic transformation experiments that were analyzed, the data can be fit with only the repair-dependent quadratic function. At low doses, the transformation frequency is strictly quadratic, but becomes sigmodial over a wider range of doses. Inclusion of data from the transition region in a traditional linear-quadratic analysis of neoplastic transformation frequency data can exaggerate the magnitude of, or create the appearance of, a linear component. Quantitative analysis of survival and transformation data shows good agreement for ultraviolet radiation; the shapes of the transformation components can be predicted from survival data. For ionizing radiations, both neutrons and x-rays, survival data overestimate the transforming ability for low to moderate doses. The presumed cause of this difference is that, unlike UV photons, a single x-ray or neutron may generate more than one lethal damage in a cell, so the distribution of such damages in the population is not accurately described by Poisson statistics. However, the complete sigmodial dose-response data for neoplastic transformations can be fit using the repair-dependent functions with all parameters determined only from transformation frequency data.

Mechanism of Action for Anti-Radiation Vaccine in Reducing the Biological Impact of High-Dose Irradiation

NASA Technical Reports Server (NTRS)

Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

2006-01-01

Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. We partially analyzed the biochemical characteristics of the SRDs. The SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

Mechanism of Action for Anti-radiation Vaccine in Reducing the Biological Impact of High-dose Gamma Irradiation

NASA Technical Reports Server (NTRS)

Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

2007-01-01

Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

Whole-Body Imaging of High-Dose Ionizing Irradiation-Induced Tissue Injuries Using 99mTc-Duramycin

PubMed Central

Johnson, Steven E.; Li, Zhixin; Liu, Yu; Moulder, John E.; Zhao, Ming

2013-01-01

High-dose ionizing irradiation can cause extensive injuries in susceptible tissues. A noninvasive imaging technique that detects a surrogate marker of apoptosis may help characterize the dynamics of radiation-induced tissue damage. The goal of this study was to prove the concept of imaging the temporal and spatial distribution of damage in susceptible tissues after high-dose radiation exposure, using 99mTc-duramycin as a phosphatidylethanolamine-binding radiopharmaceutical. Methods Rats were subjected to 15 Gy of total-body irradiation with x-rays. Planar whole-body 99mTc-duramycin scanning (n = 4 per time point) was conducted at 24, 48, and 72 h using a clinical γ-camera. On the basis of findings from planar imaging, preclinical SPECT data were acquired on control rats and on irradiated rats at 6 and 24 h after irradiation (n = 4 per time point). Imaging data were validated by γ-counting and histology, using harvested tissues in parallel groups of animals (n = 4). Results Prominent focal uptake was detected in the thymus as early as 6 h after irradiation, followed by a gradual decline in 99mTc-duramycin binding accompanied by extensive thymic atrophy. Early (6–24 h) radioactivity uptake in the gastrointestinal region was detected. Significant signal was seen in major bones in a slightly delayed fashion, at 24 h, which persisted for at least 2 d. This finding was paralleled by an elevation in signal intensity in the kidneys, spleen, and liver. The imaging results were consistent with ex vivo γ-counting results and histology. Relatively high levels of apoptosis were detected from histology in the thymus, guts, and bones, with the thymus undergoing substantial atrophy. Conclusion As a proof of principle, this study demonstrated a noninvasive imaging technique that allows characterization of the temporal and spatial dynamics of injuries in susceptible tissues during the acute phase after high-dose ionizing irradiation. Such an imaging capability will potentially be useful for global, whole-body, assessment of tissue damage after radiation exposure. These data, in turn, will contribute to our general knowledge of tissue susceptibility to ionizing irradiation, as well as the onset and progression of tissue injuries. PMID:23804327

Long-Term Effects of Exposure to Ionizing Irradiation on Periodontal Health Status – The Tinea capitis Cohort Study

PubMed Central

Sadetzki, Siegal; Chetrit, Angela; Sgan-Cohen, Harold D.; Mann, Jonathan; Amitai, Tova; Even-Nir, Hadas; Vered, Yuval

2015-01-01

Studies among long-term survivors of childhood cancer who had received high-dose irradiation therapy of 4–60 Gy, demonstrated acute and chronic dental effects, including periodontal diseases. However, the possible effects of low to moderate doses of radiation on dental health are sparse. The aim of this study is to investigate the association between childhood exposure to low–moderate doses of ionizing radiation and periodontal health following 50 years since exposure. The study population included 253 irradiated subjects (treated for Tinea capitis in the 1950s) and, 162 non-irradiated subjects. The estimated dose to the teeth was 0.2–0.4 Gy. Dental examination was performed according to the community periodontal index (CPI). Socioeconomic and health behavior variables were obtained through a personal questionnaire. Periodontal disease was operationally defined as “deep periodontal pockets.” A multivariate logistic regression model was used for the association of irradiation status and other independent variables with periodontal status. The results showed that among the irradiated subjects, 23%, (95% CI 18–28%) demonstrated complete edentulousness or insufficient teeth for CPI scoring as compared to 13% (95% CI 8–19%) among the non-irradiated subjects (p = 0.01). Periodontal disease was detected among 54% of the irradiated subjects as compared to 40% of the non-irradiated (p = 0.008). Controlling for education and smoking, the ORs for the association between radiation and periodontal disease were 1.61 (95% CI 1.01–2.57) and 1.95 (95% CI 1.1–3.5) for ever never and per 1 Gy absorbed in the salivary gland, respectively. In line with other studies, a protective effect for periodontal diseases among those with high education and an increased risk for ever smokers were observed. In conclusion, childhood exposure to low-moderate doses of ionizing radiation might be associated with later outcomes of dental health. The results add valuable data on the long-term health effects of exposure to ionizing radiation and support the implementation of the ALARA principle in childhood exposure to diagnostic procedure involving radiation. PMID:26539423

Radiation-Related Risk Analysis for Atmospheric Flight Civil Aviation Flight Personnel

NASA Technical Reports Server (NTRS)

DeAngelis, G.; Wilson, J. W.

2003-01-01

Human data on low dose rate radiation exposure and consequent effects are not readily available, and this fact generates groundtruth concerns for all risk assessment techniques for possible health effects induced by the space radiation environment, especially for long term missions like those foreseen now and in the near future. A large amount of such data may be obtained through civil aviation flight personnel cohorts, in the form of epidemiological studies on delayed health effects induced by the cosmic-ray generated atmospheric radiation environment, a high- LET low dose and low dose rate ionizing radiation with its typical neutron component, to which flight personnel are exposed all throughout their work activity. In the perspective of worldwide studies on radiation exposure of the civil aviation flight personnel, all the available results from previous studies on flight personnel radiation exposure have been examined in various ways (i.e. literature review, meta-analysis) to evaluate possible significant associations between atmospheric ionizing radiation environment and health risks, and to assess directions for future investigations. The physical characteristics of the atmospheric ionizing radiation environment make the results obtained for atmospheric flight personnel relevant for space exploration.

Micron MT29F128G08AJAAA 128GB Asynchronous Flash Memory Total Ionizing Dose Characterization Test Report

NASA Technical Reports Server (NTRS)

Campola, Michael; Wyrwas, Edward

2017-01-01

The purpose of this test was to characterize the Micron MT29F128G08AJAAAs parameter degradation for total dose response and to evaluate and compare lot date codes for sensitivity. In the test, the device was exposed to both low dose and high dose rate (HDR) irradiations using gamma radiation. Device parameters such as leakage currents, quantity of upset bits and overall chip and die health were investigated to determine which lot is more robust.

A Review of Non-Cancer Effects, Especially Circulatory and Ocular Diseases1

PubMed Central

Little, Mark P.

2014-01-01

There is a well-established association between high doses (> 5 Gy) of ionizing radiation exposure and damage to the heart and coronary arteries, although only recently have studies with high quality individual dosimetry been conducted that would enable quantification of this risk adjusting for concomitant chemotherapy. The association between lower dose exposures and late occurring circulatory disease has only recently begun to emerge in the Japanese atomic bomb survivors and in various occupationally-exposed cohorts, and is still controversial. Excess relative risks per unit dose in moderate and low dose epidemiological studies are somewhat variable, possibly a result of confounding and effect modification by well known (but unobserved) risk factors. Radiation doses of 1 Gy or more are associated with increased risk of posterior subcapsular cataract. Accumulating evidence from the Japanese atomic bomb survivors, Chernobyl liquidators, US astronauts and various other exposed groups suggest that cortical cataracts may also be associated with ionizing radiation, although there is little evidence that nuclear cataracts are radiogenic. The dose response appears to be linear, although modest thresholds (of no more than about 0.6 Gy) cannot be ruled out. A variety of other non-malignant effects have been observed after moderate/low dose exposure in various groups, in particular respiratory and digestive disease and central nervous system (and in particular neuro-cognitive) damage. However, because these are generally only observed in isolated groups, or because the evidence is excessively heterogeneous, these associations must be treated with caution. PMID:23903347

Modeling Acute Health Effects of Astronauts from Exposure to Large Solar Particle Events

NASA Technical Reports Server (NTRS)

Hu, Shaowen; Kim, Myung-Hee Y.; Cucinotta, Francis A.

2011-01-01

In space exploration outside the Earth s geomagnetic field, radiation exposure from solar particle events (SPE) presents a health concern for astronauts, that could impair their performance and result in possible failure of the mission. Acute risks are of special concern during extra-vehicular activities because of the rapid onset of SPE. However, most SPEs will not lead to acute risks but can lead to mission disruption if accurate projection methods are not available. Acute Radiation Sickness (ARS) is a group of clinical syndromes developing acutely (within several seconds to 3 days) after high dose whole-body or significant partial-body ionizing radiation exposures. The manifestation of these syndromes reflects the disturbance of physiological processes of various cellular groups damaged by radiation. Hematopoietic cells, skin, epithelium, intestine, and vascular endothelium are among the most sensitive tissues of human body to ionizing radiation. Most ARS symptoms are directly related to these tissues and other systems (nervous, endocrine, and cardiovascular, etc.) with coupled regulations. Here we report the progress in bio-mathematical models to describe the dose and time-dependent early human responses to ionizing radiation. The responses include lymphocyte depression, granulocyte modulation, fatigue and weakness syndrome, and upper gastrointestinal distress. The modest dose and dose-rates of SPEs are predicted to lead to large sparing of ARS, however detailed experimental data on a range of proton dose-rates for organ doses from 0.5 to 2 Gy is needed to validate the models. We also report on the ARRBOD code that integrates the BRYNTRN and SUMDOSE codes, which are used to estimate the SPE organ doses for astronauts under various space travel scenarios, with our models of ARS. The more recent effort is to provide easy web access to space radiation risk assessment using the ARRBOD code.

Evaluation of polymer gels and MRI as a 3-D dosimeter for intensity-modulated radiation therapy.

PubMed

Low, D A; Dempsey, J F; Venkatesan, R; Mutic, S; Markman, J; Mark Haacke, E; Purdy, J A

1999-08-01

BANG gel (MGS Research, Inc., Guilford, CT) has been evaluated for measuring intensity-modulated radiation therapy (IMRT) dose distributions. Treatment plans with target doses of 1500 cGy were generated by the Peacock IMRT system (NOMOS Corp., Sewickley, PA) using test target volumes. The gels were enclosed in 13 cm outer diameter cylindrical glass vessels. Dose calibration was conducted using seven smaller (4 cm diameter) cylindrical glass vessels irradiated to 0-1800 cGy in 300 cGy increments. Three-dimensional maps of the proton relaxation rate R2 were obtained using a 1.5 T magnetic resonance imaging (MRI) system (Siemens Medical Systems, Erlangen, Germany) and correlated with dose. A Hahn spin echo sequence was used with TR = 3 s, TE = 20 and 100 ms, NEX = 1, using 1 x 1 x 3 mm3 voxels. The MRI measurements were repeated weekly to identify the gel-aging characteristics. Ionization chamber, thermoluminescent dosimetry (TLD), and film dosimetry measurements of the IMRT dose distributions were obtained to compare against the gel results. The other dosimeters were used in a phantom with the same external cross-section as the gel phantom. The irradiated R2 values of the large vessels did not precisely track the smaller vessels, so the ionization chamber measurements were used to normalize the gel dose distributions. The point-to-point standard deviation of the gel dose measurements was 7.0 cGy. When compared with the ionization chamber measurements averaged over the chamber volume, 1% agreement was obtained. Comparisons against radiographic film dose distribution measurements and the treatment planning dose distribution calculation were used to determine the spatial localization accuracy of the gel and MRI. Spatial localization was better than 2 mm, and the dose was accurately determined by the gel both within and outside the target. The TLD chips were placed throughout the phantom to determine gel measurement precision in high- and low-dose regions. A multidimensional dose comparison tool that simultaneously examines the dose-difference and distance-to-agreement was used to evaluate the gel in both low-and high-dose gradient regions. When 3% and 3 mm criteria were used for the comparisons, more than 90% of the TLD measurements agreed with the gel, with the worst of 309 TLD chip measurements disagreeing by 40% of the criteria. All four MRI measurement session gel-measured dose distributions were compared to evaluate the time behavior of the gel. The low-dose regions were evaluated by comparison with TLD measurements at selected points, while high-dose regions were evaluated by directly comparing measured dose distributions. Tests using the multidimensional comparison tool showed detectable degradation beyond one week postirradiation, but all low-dose measurements passed relative to the test criteria and the dose distributions showed few regions that failed.

Identifying the health risks from very low-dose sparsely ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dreyer, N.A.; Friedlander, E.

1982-06-01

The health risks from low-dose sparsely ionizing (low-LET) radiation have been the subject of continued debate. At present, quantitative estimates of risk are extremely uncertain due to the controversy surrounding both the dosimetry for A-bomb survivor data and the choice of mathematical models for extrapolating risk from high to low doses. Nevertheless, much can be learned about the nature of the health risks by reviewing the epidemiologic literature. We present a summary of diseases which have been associated with low-LET radiation (less than 1000 rad) in at least two independent studies, according to the mean cumulative organ dose at whichmore » the disease was observed. At organ doses of less than or equal to 50 rad, the only diseases that have been reported consistently are thyroid cancer, salivary gland tumors, and leukemia. The first two diseases were observed in association with x-ray epilation of the scalp for tinea capitis, a therapy which is no longer employed. On the other hand, leukemia has been observed repeatedly to occur at cumulative doses of greater than or equal to 30 rad low-LET radiation.« less

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA GSFC and NEPP

NASA Technical Reports Server (NTRS)

Topper, Alyson D.; Campola, Michael J.; Chen, Dakai; Casey, Megan C.; Yau, Ka-Yen; Label, Kenneth A.; Cochran, Donna J.; O'Bryan, Martha V.

2017-01-01

Total ionizing dose and displacement damage testing was performed to characterize and determine the suitability of candidate electronics for NASA space utilization. Devices tested include opto-electronics, digital, analog, linear bipolar devices, and hybrid devices.

Effects of ionizing radiation in ginkgo and guarana [rapid communication

NASA Astrophysics Data System (ADS)

Rabelo Soriani, Renata; Cristina Satomi, Lucilia; Pinto, Terezinha de Jesus A.

2005-07-01

Raw plant materials normally carry high bioburden due to their origin, offering potential hazards to consumers. The use of decontamination processes is therefore an important step towards the consumer safety and therapeutical efficiency. Several authors have reported the treatment of medicinal herbs with ionizing radiation. This work evaluated the effects of different radiation doses on the microbial burden and chemical constituents of ginkgo ( Ginkgo biloba L.) and guaraná ( Paullinia cupana H.B.K.).

Comparison of depth-dose distributions of proton therapeutic beams calculated by means of logical detectors and ionization chamber modeled in Monte Carlo codes

NASA Astrophysics Data System (ADS)

Pietrzak, Robert; Konefał, Adam; Sokół, Maria; Orlef, Andrzej

2016-08-01

The success of proton therapy depends strongly on the precision of treatment planning. Dose distribution in biological tissue may be obtained from Monte Carlo simulations using various scientific codes making it possible to perform very accurate calculations. However, there are many factors affecting the accuracy of modeling. One of them is a structure of objects called bins registering a dose. In this work the influence of bin structure on the dose distributions was examined. The MCNPX code calculations of Bragg curve for the 60 MeV proton beam were done in two ways: using simple logical detectors being the volumes determined in water, and using a precise model of ionization chamber used in clinical dosimetry. The results of the simulations were verified experimentally in the water phantom with Marcus ionization chamber. The average local dose difference between the measured relative doses in the water phantom and those calculated by means of the logical detectors was 1.4% at first 25 mm, whereas in the full depth range this difference was 1.6% for the maximum uncertainty in the calculations less than 2.4% and for the maximum measuring error of 1%. In case of the relative doses calculated with the use of the ionization chamber model this average difference was somewhat greater, being 2.3% at depths up to 25 mm and 2.4% in the full range of depths for the maximum uncertainty in the calculations of 3%. In the dose calculations the ionization chamber model does not offer any additional advantages over the logical detectors. The results provided by both models are similar and in good agreement with the measurements, however, the logical detector approach is a more time-effective method.

A test of the IAEA code of practice for absorbed dose determination in photon and electron beams

NASA Astrophysics Data System (ADS)

Leitner, Arnold; Tiefenboeck, Wilhelm; Witzani, Josef; Strachotinsky, Christian

1990-12-01

The IAEA (International Atomic Energy Agency) code of practice TRS 277 gives recommendations for absorbed dose determination in high energy photon and electron beams based on the use of ionization chambers calibrated in terms of exposure of air kerma. The scope of the work was to test the code for cobalt 60 gamma radiation and for several radiation qualities at four different types of electron accelerators and to compare the ionization chamber dosimetry with ferrous sulphate dosimetry. The results show agreement between the two methods within about one per cent for all the investigated qualities. In addition the response of the TLD capsules of the IAEA/WHO TL dosimetry service was determined.

A novel multitarget model of radiation-induced cell killing based on the Gaussian distribution.

PubMed

Zhao, Lei; Mi, Dong; Sun, Yeqing

2017-05-07

The multitarget version of the traditional target theory based on the Poisson distribution is still used to describe the dose-survival curves of cells after ionizing radiation in radiobiology and radiotherapy. However, noting that the usual ionizing radiation damage is the result of two sequential stochastic processes, the probability distribution of the damage number per cell should follow a compound Poisson distribution, like e.g. Neyman's distribution of type A (N. A.). In consideration of that the Gaussian distribution can be considered as the approximation of the N. A. in the case of high flux, a multitarget model based on the Gaussian distribution is proposed to describe the cell inactivation effects in low linear energy transfer (LET) radiation with high dose-rate. Theoretical analysis and experimental data fitting indicate that the present theory is superior to the traditional multitarget model and similar to the Linear - Quadratic (LQ) model in describing the biological effects of low-LET radiation with high dose-rate, and the parameter ratio in the present model can be used as an alternative indicator to reflect the radiation damage and radiosensitivity of the cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulator training to minimize ionizing radiation exposure in the catheterization laboratory.

PubMed

Katz, Aric; Shtub, Avraham; Solomonica, Amir; Poliakov, Adva; Roguin, Ariel

2017-03-01

To learn about radiation and how to lower it. Patients and operators are routinely exposed to high doses of ionizing radiation during catheterization procedures. This increased exposure to ionizing radiation is partially due to a lack of awareness to the effects of ionizing radiation, and lack of knowledge on the distribution and behavior of scattered radiation. A simulator, which incorporates data on scattered ionizing radiation, was built based on multiple phantom measurements and used for teaching radiation safety. The validity of the simulator was confirmed in three catheterization laboratories and tested by 20 interventional cardiologists. All evaluators were tested by an objective knowledge examination before, immediately following, and 12 weeks after simulator-based learning and training. A subjective Likert questionnaire on satisfaction with simulation-based learning and training was also completed. The 20 evaluators learned and retained the knowledge that they gained from using the simulator: the average scores of the knowledge examination pre-simulator training was 54 ± 15% (mean ± standard deviation), and this score significantly increased after training to 94 ± 10% (p < 0.001). The evaluators also reported high levels of satisfaction following simulation-based learning and training according to the results of the subjective Likert questionnaire. Simulators can be used to train cardiology staff and fellows and to further educate experienced personnel on radiation safety. As a result of simulator training, the operator gains knowledge, which can then be applied in the catheterization laboratory in order to reduce radiation doses to the patient and to the operator, thereby improving the safety of the intervention.

High dose-per-pulse electron beam dosimetry - A model to correct for the ion recombination in the Advanced Markus ionization chamber.

PubMed

Petersson, Kristoffer; Jaccard, Maud; Germond, Jean-François; Buchillier, Thierry; Bochud, François; Bourhis, Jean; Vozenin, Marie-Catherine; Bailat, Claude

2017-03-01

The purpose of this work was to establish an empirical model of the ion recombination in the Advanced Markus ionization chamber for measurements in high dose rate/dose-per-pulse electron beams. In addition, we compared the observed ion recombination to calculations using the standard Boag two-voltage-analysis method, the more general theoretical Boag models, and the semiempirical general equation presented by Burns and McEwen. Two independent methods were used to investigate the ion recombination: (a) Varying the grid tension of the linear accelerator (linac) gun (controls the linac output) and measuring the relative effect the grid tension has on the chamber response at different source-to-surface distances (SSD). (b) Performing simultaneous dose measurements and comparing the dose-response, in beams with varying dose rate/dose-per-pulse, with the chamber together with dose rate/dose-per-pulse independent Gafchromic™ EBT3 film. Three individual Advanced Markus chambers were used for the measurements with both methods. All measurements were performed in electron beams with varying mean dose rate, dose rate within pulse, and dose-per-pulse (10 -2  ≤ mean dose rate ≤ 10 3 Gy/s, 10 2  ≤ mean dose rate within pulse ≤ 10 7  Gy/s, 10 -4  ≤ dose-per-pulse ≤ 10 1  Gy), which was achieved by independently varying the linac gun grid tension, and the SSD. The results demonstrate how the ion collection efficiency of the chamber decreased as the dose-per-pulse increased, and that the ion recombination was dependent on the dose-per-pulse rather than the dose rate, a behavior predicted by Boag theory. The general theoretical Boag models agreed well with the data over the entire investigated dose-per-pulse range, but only for a low polarizing chamber voltage (50 V). However, the two-voltage-analysis method and the Burns & McEwen equation only agreed with the data at low dose-per-pulse values (≤ 10 -2 and ≤ 10 -1  Gy, respectively). An empirical model of the ion recombination in the chamber was found by fitting a logistic function to the data. The ion collection efficiency of the Advanced Markus ionization chamber decreases for measurements in electron beams with increasingly higher dose-per-pulse. However, this chamber is still functional for dose measurements in beams with dose-per-pulse values up toward and above 10 Gy, if the ion recombination is taken into account. Our results show that existing models give a less-than-accurate description of the observed ion recombination. This motivates the use of the presented empirical model for measurements with the Advanced Markus chamber in high dose-per-pulse electron beams, as it enables accurate absorbed dose measurements (uncertainty estimation: 2.8-4.0%, k = 1). The model depends on the dose-per-pulse in the beam, and it is also influenced by the polarizing chamber voltage, with increasing ion recombination with a lowering of the voltage. © 2017 American Association of Physicists in Medicine.

Current Status and Future Challenges in Risk-Based Radiation Engineering

NASA Technical Reports Server (NTRS)

Pellish, Jonathan A.

2017-01-01

This presentation covers the basis and challenges for radiation effects in electronic systems. The three main types of radiation effects in electronics are: 1) total ionizing dose (TID), 2) total non-ionizing dose (TNID) / displacement damage dose (DDD), and 3) single-event effect (SEE). Some content on relevant examples of effects, current concerns, and possible environmental model-driven solutions are also included.

Monte-Carlo Simulation of Radiation Track Structure and Calculation of Dose Deposition in Nanovolumes

NASA Technical Reports Server (NTRS)

Plante, I.; Cucinotta, F. A.

2010-01-01

INTRODUCTION: The radiation track structure is of crucial importance to understand radiation damage to molecules and subsequent biological effects. Of a particular importance in radiobiology is the induction of double-strand breaks (DSBs) by ionizing radiation, which are caused by clusters of lesions in DNA, and oxidative damage to cellular constituents leading to aberrant signaling cascades. DSB can be visualized within cell nuclei with gamma-H2AX experiments. MATERIAL AND METHODS: In DSB induction models, the DSB probability is usually calculated by the local dose obtained from a radial dose profile of HZE tracks. In this work, the local dose imparted by HZE ions is calculated directly from the 3D Monte-Carlo simulation code RITRACKS. A cubic volume of 5 micron edge (Figure 1) is irradiated by a (Fe26+)-56 ion of 1 GeV/amu (LET approx.150 keV/micron) and by a fluence of 450 H+ ions, 300 MeV/amu (LET approx. 0.3 keV/micron). In both cases, the dose deposited in the volume is approx.1 Gy. The dose is then calculated into each 3D pixels (voxels) of 20 nm edge and visualized in 3D. RESULTS AND DISCUSSION: The dose is deposited uniformly in the volume by the H+ ions. The voxels which receive a high dose (orange) corresponds to electron track ends. The dose is deposited differently by the 56Fe26+ ion. Very high dose (red) is deposited in voxels with direct ion traversal. Voxels with electron track ends (orange) are also found distributed around the path of the track. In both cases, the appearance of the dose distribution looks very similar to DSBs seen in gammaH2AX experiments, particularly when the visualization threshold is applied. CONCLUSION: The refinement of the dose calculation to the nanometer scale has revealed important differences in the energy deposition between high- and low-LET ions. Voxels of very high dose are only found in the path of high-LET ions. Interestingly, experiments have shown that DSB induced by high-LET radiation are more difficult to repair. Therefore, this new approach may be useful to understand the nature of DSB and oxidative damage induced by ionizing radiation.

Ultra-low power high temperature and radiation hard complementary metal-oxide-semiconductor (CMOS) silicon-on-insulator (SOI) voltage reference.

PubMed

Boufouss, El Hafed; Francis, Laurent A; Kilchytska, Valeriya; Gérard, Pierre; Simon, Pascal; Flandre, Denis

2013-12-13

This paper presents an ultra-low power CMOS voltage reference circuit which is robust under biomedical extreme conditions, such as high temperature and high total ionized dose (TID) radiation. To achieve such performances, the voltage reference is designed in a suitable 130 nm Silicon-on-Insulator (SOI) industrial technology and is optimized to work in the subthreshold regime of the transistors. The design simulations have been performed over the temperature range of -40-200 °C and for different process corners. Robustness to radiation was simulated using custom model parameters including TID effects, such as mobilities and threshold voltages degradation. The proposed circuit has been tested up to high total radiation dose, i.e., 1 Mrad (Si) performed at three different temperatures (room temperature, 100 °C and 200 °C). The maximum drift of the reference voltage V(REF) depends on the considered temperature and on radiation dose; however, it remains lower than 10% of the mean value of 1.5 V. The typical power dissipation at 2.5 V supply voltage is about 20 μW at room temperature and only 75 μW at a high temperature of 200 °C. To understand the effects caused by the combination of high total ionizing dose and temperature on such voltage reference, the threshold voltages of the used SOI MOSFETs were extracted under different conditions. The evolution of V(REF) and power consumption with temperature and radiation dose can then be explained in terms of the different balance between fixed oxide charge and interface states build-up. The total occupied area including pad-ring is less than 0.09 mm2.

Implementation of ionizing radiation environment requirements for Space Station

NASA Technical Reports Server (NTRS)

Boeder, Paul A.; Watts, John W.

1993-01-01

Proper functioning of Space Station hardware requires that the effects of high-energy ionizing particles from the natural environment and (possibly) from man-made sources be considered during design. At the Space Station orbit of 28.5-deg inclination and 330-440 km altitude, geomagnetically trapped protons and electrons contribute almost all of the dose, while galactic cosmic rays and anomalous cosmic rays may produce Single Event Upsets (SEUs), latchups, and burnouts of microelectronic devices. Implementing ionizing radiation environment requirements for Space Station has been a two part process, including the development of a description of the environment for imposing requirements on the design and the development of a control process for assessing how well the design addresses the effects of the ionizing radiation environment. We will review both the design requirements and the control process for addressing ionizing radiation effects on Space Station.

Total Ionizing Dose Test of Microsemi's Silicon Switching Transistors JANTXV2N2222AUB and 2N2907AUB

NASA Technical Reports Server (NTRS)

Campola, M.; Freeman, B.; Yau, K.

2017-01-01

Microsemi's silicon switching transistors, JANTXV2N2222AUB and 2N2907AUB, were tested for total ionizing dose (TID) response beginning on July 11, 2016. This test served as the radiation lot acceptance test (RLAT) for the lot date code (LDC) tested. Low dose rate (LDR) irradiations were performed in this test so that the device susceptibility to enhanced low dose rate sensitivity (ELDRS) could be determined.

CHAMBER - IONIZATION - EXPERIMENT - GEMINI-TITAN (GT)-6 EQUIPMENT - CAPE

NASA Image and Video Library

1965-12-10

S65-61788 (For release: 11 Dec. 1965) --- Close-up view of equipment which will be used in the D-8 (Radiation in Spacecraft) experiment on the National Aeronautics and Space Administration's Gemini-6 spaceflight. This experiment is designed to make highly accurate measurements of the absorbed dose rate of radiation which penetrates the Gemini spacecraft, and determine the spatial distribution of dose levels inside the spacecraft particularly in the crew area. This is experimentation of the U.S. Air Force Weapons Laboratory, Kirtland AFB, N.M. LOWER LEFT: The second ionization chamber, this one is unshielded. This chamber can be removed from its bracket by the astronaut who will periodically take measurements at various locations in the spacecraft. Nearby is Passive Dosimeter Unit which is one of five small packets each containing a standard pocket ionization chamber, gamma electron sensitive film, glass needles and thermo luminescent dosimeters which are mounted at various locations in the cabin. UPPER LEFT: Photo illustrates how ionization chamber can be removed from bracket for measurements. LOWER RIGHT: Shield of bulb-shaped chamber will be removed (shown in photo) as the spacecraft passes through the South Atlantic anomaly, the area where the radiation belt dips closest to Earth's surface. UPPER RIGHT: Dome-shaped object is shield covering one of two Tissue Equivalent Ionization Chambers (sensors) which will read out continuously the instantaneous rate at which dose is delivered during the flight. This chamber is mounted permanently. The information will be recorded aboard the spacecraft, and will also be received directly by ground stations. This chamber is shielded to simulate the amount of radiation the crew members are receiving beneath their skin. Photo credit: NASA or National Aeronautics and Space Administration

Evaluation of the dosimetric properties of a diode detector for small field proton radiosurgery.

PubMed

McAuley, Grant A; Teran, Anthony V; Slater, Jerry D; Slater, James M; Wroe, Andrew J

2015-11-08

The small fields and sharp gradients typically encountered in proton radiosurgery require high spatial resolution dosimetric measurements, especially below 1-2 cm diameters. Radiochromic film provides high resolution, but requires postprocessing and special handling. Promising alternatives are diode detectors with small sensitive volumes (SV) that are capable of high resolution and real-time dose acquisition. In this study we evaluated the PTW PR60020 proton dosimetry diode using radiation fields and beam energies relevant to radiosurgery applications. Energies of 127 and 157 MeV (9.7 to 15 cm range) and initial diameters of 8, 10, 12, and 20mm were delivered using single-stage scattering and four modulations (0, 15, 30, and 60mm) to a water tank in our treatment room. Depth dose and beam profile data were compared with PTW Markus N23343 ionization chamber, EBT2 Gafchromic film, and Monte Carlo simulations. Transverse dose profiles were measured using the diode in "edge-on" orientation or EBT2 film. Diode response was linear with respect to dose, uniform with dose rate, and showed an orientation-dependent (i.e., beam parallel to, or perpendicular to, detector axis) response of less than 1%. Diodevs. Markus depth-dose profiles, as well as Markus relative dose ratio vs. simulated dose-weighted average lineal energy plots, suggest that any LET-dependent diode response is negligible from particle entrance up to the very distal portion of the SOBP for the energies tested. Finally, while not possible with the ionization chamber due to partial volume effects, accurate diode depth-dose measurements of 8, 10, and 12 mm diameter beams were obtained compared to Monte Carlo simulations. Because of the small SV that allows measurements without partial volume effects and the capability of submillimeter resolution (in edge-on orientation) that is crucial for small fields and high-dose gradients (e.g., penumbra, distal edge), as well as negligible LET dependence over nearly the full the SOBP, the PTW proton diode proved to be a useful high-resolution, real-time metrology device for small proton field radiation measurements such as would be encountered in radiosurgery applications.

GaAs MMIC: recovery from upset by x-ray pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Armendariz, M.G.; Castle, J.G. Jr.

1986-01-01

Tolerance for fast neutrons and total ionizing dose is a feature of GaAs microwave monolithic integrated circuits (MMIC). However, upset during an ionizing pulse is expected to occur and delayed recovery due to backgating may be a problem. The purpose of this study of an experimental MMIC design is to observe the recovery of oscillator power output following upset by a short ionizing pulse as a function of applied bias, dose per pulse and case temperature.

Characteristics of a p-Si detector in high energy electron fields.

PubMed

Rikner, G

1985-01-01

Comparison of depth ionization distributions from a silicon semiconductor detector and depth dose curves from a plane parallel ionization chamber show that a semiconductor detector of p-type is well suited for relative electron dosimetry in the energy range of 6 to 20 MeV in Ep,0. Maximum deviations of the order of 1.5 per cent and of 1 mm were obtained down to a phantom depth of about 1 mm. The directional dependence of the detector was about 4 per cent.

Performance parameters of a liquid filled ionization chamber array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poppe, B.; Stelljes, T. S.; Looe, H. K.

2013-08-15

Purpose: In this work, the properties of the two-dimensional liquid filled ionization chamber array Octavius 1000SRS (PTW-Freiburg, Germany) for use in clinical photon-beam dosimetry are investigated.Methods: Measurements were carried out at an Elekta Synergy and Siemens Primus accelerator. For measurements of stability, linearity, and saturation effects of the 1000SRS array a Semiflex 31013 ionization chamber (PTW-Freiburg, Germany) was used as a reference. The effective point of measurement was determined by TPR measurements of the array in comparison with a Roos chamber (type 31004, PTW-Freiburg, Germany). The response of the array with varying field size and depth of measurement was evaluatedmore » using a Semiflex 31010 ionization chamber as a reference. Output factor measurements were carried out with a Semiflex 31010 ionization chamber, a diode (type 60012, PTW-Freiburg, Germany), and the detector array under investigation. The dose response function for a single detector of the array was determined by measuring 1 cm wide slit-beam dose profiles and comparing them against diode-measured profiles. Theoretical aspects of the low pass properties and of the sampling frequency of the detector array were evaluated. Dose profiles measured with the array and the diode detector were compared, and an intensity modulated radiation therapy (IMRT) field was verified using the Gamma-Index method and the visualization of line dose profiles.Results: The array showed a short and long term stability better than 0.1% and 0.2%, respectively. Fluctuations in linearity were found to be within ±0.2% for the vendor specified dose range. Saturation effects were found to be similar to those reported in other studies for liquid-filled ionization chambers. The detector's relative response varied with field size and depth of measurement, showing a small energy dependence accounting for maximum signal deviations of ±2.6% from the reference condition for the setup used. The σ-values of the Gaussian dose response function for a single detector of the array were found to be (0.72 ± 0.25) mm at 6 MV and (0.74 ± 0.25) mm at 15 MV and the corresponding low pass cutoff frequencies are 0.22 and 0.21 mm{sup −1}, respectively. For the inner 5 × 5 cm{sup 2} region and the outer 11 × 11 cm{sup 2} region of the array the Nyquist theorem is fulfilled for maximum sampling frequencies of 0.2 and 0.1 mm{sup −1}, respectively. An IMRT field verification with a Gamma-Index analysis yielded a passing rate of 95.2% for a 3 mm/3% criterion with a TPS calculation as reference.Conclusions: This study shows the applicability of the Octavius 1000SRS in modern dosimetry. Output factor and dose profile measurements illustrated the applicability of the array in small field and stereotactic dosimetry. The high spatial resolution ensures adequate measurements of dose profiles in regular and intensity modulated photon-beam fields.« less

Single Low-Dose Ionizing Radiation Induces Genotoxicity in Adult Zebrafish and its Non-Irradiated Progeny.

PubMed

Lemos, J; Neuparth, T; Trigo, M; Costa, P; Vieira, D; Cunha, L; Ponte, F; Costa, P S; Metello, L F; Carvalho, A P

2017-02-01

This study investigated to what extent a single exposure to low doses of ionizing radiation can induce genotoxic damage in irradiated adult zebrafish (Danio rerio) and its non-irradiated F1 progeny. Four groups of adult zebrafish were irradiated with a single dose of X-rays at 0 (control), 100, 500 and 1000 mGy, respectively, and couples of each group were allowed to reproduce following irradiation. Blood of parental fish and whole-body offspring were analysed by the comet assay for detection of DNA damage. The level of DNA damage in irradiated parental fish increased in a radiation dose-dependent manner at day 1 post-irradiation, but returned to the control level thereafter. The level of DNA damage in the progeny was directly correlated with the parental irradiation dose. Results highlight the genotoxic risk of a single exposure to low-dose ionizing radiation in irradiated individuals and also in its non-irradiated progeny.

Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate–Dependent Manner

PubMed Central

Vieira Dias, Juliana; Gloaguen, Celine; Kereselidze, Dimitri; Manens, Line; Tack, Karine; Ebrahimian, Teni G

2018-01-01

A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR. PMID:29531508

Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate-Dependent Manner.

PubMed

Vieira Dias, Juliana; Gloaguen, Celine; Kereselidze, Dimitri; Manens, Line; Tack, Karine; Ebrahimian, Teni G

2018-01-01

A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR.

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA Goddard Space Flight Center and Selected NASA Electronic Parts and Packaging Program

NASA Technical Reports Server (NTRS)

Topper, Alyson D.; Campola, Michael J.; Chen, Dakai; Casey, Megan C.; Yau, Ka-Yen; Cochran, Donna J.; LaBel, Kenneth A.; Ladbury, Raymond L.; Lauenstein, Jean-Marie; Mondy, Timothy K.;

Current Total Ionizing Dose Results and Displacement Damage Results for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Kniffin, Scott D.; LaBel, Kenneth A.; OBryan, Martha V.; Reed, Robert A.; Ladbury, Ray L.; Howard, James W., Jr.; Poivey, Christian; Buchner, Stephen P.; Marshall, Cheryl J.

2004-01-01

We present data on the vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage. Devices tested include optoelectronics, digital, analog, linear bipolar devices, hybrid devices, Analog-to-Digital Converters (ADCs), and Digital-to-Analog Converters (DACS), among others.

Total Ionizing Dose Results and Displacement Damage Results for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Kniffin, Scott D.; LaBel, Kenneth A.; OBryan, Martha V.; Reed, Robert A.; Ladbury, Ray L.; Howard, James W., Jr.; Poivey, Christian; Buchner, Stephen P.; Marshall, Cheryl J.

2003-01-01

We present data on the vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage. Devices tested include optoelectronics, digital, analog, linear bipolar devices, hybrid devices, Analog-to-Digital Converters (ADCs), and Digital-to-Analog Converters (DACs), among others.

Radiation tolerance in the tardigrade Milnesium tardigradum.

PubMed

Horikawa, Daiki D; Sakashita, Tetsuya; Katagiri, Chihiro; Watanabe, Masahiko; Kikawada, Takahiro; Nakahara, Yuichi; Hamada, Nobuyuki; Wada, Seiichi; Funayama, Tomoo; Higashi, Seigo; Kobayashi, Yasuhiko; Okuda, Takashi; Kuwabara, Mikinori

2006-12-01

Tardigrades are known to survive high doses of ionizing radiation. However, there have been no reports about radiation effects in tardigrades under culture conditions. In this study, we investigated tolerance of the tardigrade, Milnesium tardigradum, against gamma-rays and heavy ions by determining short-term or long-term survival, and reproductive ability after irradiation. Hydrated and anhydrobiotic animals were exposed to gamma-rays (1000 - 7000 Gy) or heavy ions (1000 - 8000 Gy) to evaluate short-term survival at 2, 24 and 48 h post-irradiation. Long-term survival and reproduction were observed up to 31 days after irradiation with gamma-rays (1000 - 4000 Gy). At 48 h after irradiation, median lethal doses were 5000 Gy (gamma-rays) and 6200 Gy (heavy ions) in hydrated animals, and 4400 Gy (gamma-rays) and 5200 Gy (heavy ions) in anhydrobiotic ones. Gamma-irradiation shortened average life span in a dose-dependent manner both in hydrated and anhydrobiotic groups. No irradiated animals laid eggs with one exception in which a hydrated animal irradiated with 2000 Gy of gamma-rays laid 3 eggs, and those eggs failed to hatch, whereas eggs produced by non-irradiated animals hatched successfully. M. tardigradum survives high doses of ionizing radiation in both hydrated and anhydrobiotic states, but irradiation with >1000 Gy makes them sterile.

Enhancing the biological degradability of sulfamethoxazole by ionizing radiation treatment in aqueous solution

NASA Astrophysics Data System (ADS)

Sági, Gyuri; Kovács, Krisztina; Bezsenyi, Anikó; Csay, Tamás; Takács, Erzsébet; Wojnárovits, László

2016-07-01

Changes of biodegradability and toxicity were followed up on aqueous solutions of sulfamethoxazole (SMX), during ionizing radiation treatment. The biodegradability of SMX (0.1 mmol dm-3) was specified by five-day biological oxygen demand (BOD5), using municipal activated sludge, and the results showed an improvement with applying only 0.4 kGy dose. BOD5 further increased with prolonged irradiation, indicating a conversion of SMX, a non-biodegradable compound, to biologically treatable substances. At 2.5 kGy dose, the BOD5/COD ratio increased from 0 to 0.16. The total organic carbon (TOC) content showed a decrease of only 15% at this point, thus high degree of mineralization is not necessary to make SMX digestible for the low concentrations of microorganisms used during BOD5 measurements. Increment in respiration inhibition of municipal activated sludge was observed with increasing the dose. The EC50 values showed a decrease of one order of magnitude when changing the dose from 0.4 kGy to 2.5 kGy. The increase of inhibition and formation of H2O2 showed a strong correlation.

Small Total Dose Measurement System for SOHLA-1 and SDS-1

NASA Astrophysics Data System (ADS)

Kimoto, Yugo; Satoh, Yohei; Tachihara, Hiroshi

The Japanese Aerospace Exploration Agency (JAXA) uses monitors on board satellites to measure and record in-flight data about ionization effects in space. A compact, total-dose measurement system for small satellites—Space-Oriented Higashiosaka Leading Association -1 (SOHLA-1) and Small Demonstration-Satellite -1 (SDS-1)—was developed based on a prior system for measuring total ionizing dose effects. Especially, the sensor for SDS-1 is much smaller than the sensor for SOHLA-1. The sensor for SDS-1 is 8 mm wide × 3 mm high × 19 mm long and weighs approximately 4 g with 500 mm with its wire harness. An 8-pin Lead less Chip Carrier (LCC) RADFET and temperature sensor are arranged on it. Seven sensors are mounted on some components inside the SDS-1. The sensor for SOHLA-1 is a 14-pin Dual Inline Package (DIP) type RADFET. The four sensors, which have RADFET on a printed board covered with an aluminum chassis, are mounted both inside and outside the satellite. This report presents small total dose measurement systems and ground irradiation test results for two small satellites.

Radiation-stability of smectite.

PubMed

Sorieul, Stéphanie; Allard, Thierry; Wang, Lumin M; Grambin-Lapeyre, Caroline; Lian, Jie; Calas, Georges; Ewings, Rodney C

2008-11-15

The safety assessment of geological repositories for high-level nuclear waste and spent nuclear fuel requires an understanding of the response of materials to high temperatures and intense radiation fields. Clays, such as smectite, have been proposed as backfill material around waste packages, but their response to intense radiation from short-lived fission products and alpha decay of sorbed actinides remains poorly understood. Cumulative doses may amorphize clays and may alter their properties of sorption, swelling, or water retention. We describe the amorphization of smectites induced by electron and heavy ion irradiations to simulate ionizing radiation and alpha recoil nuclei, respectively. A new "bell-shaped" evolution of the amorphization dose with temperature has been determined. The maximum dose for amorphization occurs at about 300-400 degrees C, showing that temperature-induced dehydroxylation enhances amorphization. The exact shape of the bell-shaped curves depends on the interlayer cation. At ambient temperature, ionizing radiation and alpha-decay events do not show the same efficiency. The former results in amorphization at doses between 10(10)-10(11) Gy which are greater than the total radiation dose expected for radioactive waste over 10(6) years. In contrast, alpha-decay events amorphize clays at doses as low as 0.13-0.16 displacements per atom, i.e. doses consistent with nuclear waste accumulated over approximately 1000 yrs. However, the limited penetration of alpha particles and recoil nuclei, in the 100 nm - 20 microm range, will minimize damage. Clays will not be amorphized unless the waste package is breached and released actinides are heavily sorbed onto the clay overpack.

Cancer and non-cancer brain and eye effects of chronic low-dose ionizing radiation exposure

PubMed Central

2012-01-01

Background According to a fundamental law of radiobiology (“Law of Bergonié and Tribondeau”, 1906), the brain is a paradigm of a highly differentiated organ with low mitotic activity, and is thus radio-resistant. This assumption has been challenged by recent evidence discussed in the present review. Results Ionizing radiation is an established environmental cause of brain cancer. Although direct evidence is lacking in contemporary fluoroscopy due to obvious sample size limitation, limited follow-up time and lack of focused research, anecdotal reports of clusters have appeared in the literature, raising the suspicion that brain cancer may be a professional disease of interventional cardiologists. In addition, although terminally differentiated neurons have reduced or mild proliferative capacity, and are therefore not regarded as critical radiation targets, adult neurogenesis occurs in the dentate gyrus of the hippocampus and the olfactory bulb, and is important for mood, learning/memory and normal olfactory function, whose impairment is a recognized early biomarker of neurodegenerative diseases. The head doses involved in radiotherapy are high, usually above 2 Sv, whereas the low-dose range of professional exposure typically involves lifetime cumulative whole-body exposure in the low-dose range of < 200 mSv, but with head exposure which may (in absence of protection) arrive at a head equivalent dose of 1 to 3 Sv after a professional lifetime (corresponding to a brain equivalent dose around 500 mSv). Conclusions At this point, a systematic assessment of brain (cancer and non-cancer) effects of chronic low-dose radiation exposure in interventional cardiologists and staff is needed. PMID:22540409

A diamond detector in the dosimetry of high-energy electron and photon beams.

PubMed

Laub, W U; Kaulich, T W; Nüsslin, F

1999-09-01

A diamond detector type 60003 (PTW Freiburg) was examined for the purpose of dosimetry with 4-20 MeV electron beams and 4-25 MV photon beams. Results were compared with those obtained by using a Markus chamber for electron beams and an ionization chamber for photon beams. Dose distributions were measured in a water phantom with the detector connected to a Unidos electrometer (PTW Freiburg). After a pre-irradiation of about 5 Gy the diamond detector shows a stability in response which is better than that of an ionization chamber. The current of the diamond detector was measured under variation of photon beam dose rate between 0.1 and 7 Gy min(-1). Different FSDs were chosen. Furthermore the pulse repetition frequency and the depth of the detector were changed. The electron beam dose rate was varied between 0.23 and 4.6 Gy min(-1) by changing the pulse-repetition frequency. The response shows no energy dependence within the covered photon-beam energy range. Between 4 MeV and 18 MeV electron beam energy it shows only a small energy dependence of about 2%, as expected from theory. For smaller electron energies the response increases significantly and an influence of the contact material used for the diamond detector can be surmised. A slight sublinearity of the current and dose rate was found. Detector current and dose rate are related by the expression i alpha Ddelta, where i is the detector current, D is the dose rate and delta is a correction factor of approximately 0.963. Depth-dose curves of photon beams, measured with the diamond detector, show a slight overestimation compared with measurements with the ionization chamber. This overestimation is compensated for by the above correction term. The superior spatial resolution of the diamond detector leads to minor deviations between depth-dose curves of electron beams measured with a Markus chamber and a diamond detector.

Dosimetry for Small and Nonstandard Fields

NASA Astrophysics Data System (ADS)

Junell, Stephanie L.

The proposed small and non-standard field dosimetry protocol from the joint International Atomic Energy Agency (IAEA) and American Association of Physicist in Medicine working group introduces new reference field conditions for ionization chamber based reference dosimetry. Absorbed dose beam quality conversion factors (kQ factors) corresponding to this formalism were determined for three different models of ionization chambers: a Farmer-type ionization chamber, a thimble ionization chamber, and a small volume ionization chamber. Beam quality correction factor measurements were made in a specially developed cylindrical polymethyl methacrylate (PMMA) phantom and a water phantom using thermoluminescent dosimeters (TLDs) and alanine dosimeters to determine dose to water. The TLD system for absorbed dose to water determination in high energy photon and electron beams was fully characterized as part of this dissertation. The behavior of the beam quality correction factor was observed as it transfers the calibration coefficient from the University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) 60Co reference beam to the small field calibration conditions of the small field formalism. TLD-determined beam quality correction factors for the calibration conditions investigated ranged from 0.97 to 1.30 and had associated standard deviations from 1% to 3%. The alanine-determined beam quality correction factors ranged from 0.996 to 1.293. Volume averaging effects were observed with the Farmer-type ionization chamber in the small static field conditions. The proposed small and non-standard field dosimetry protocols new composite-field reference condition demonstrated its potential to reduce or remove ionization chamber volume dependancies, but the measured beam quality correction factors were not equal to the standard CoP's kQ, indicating a change in beam quality in the small and non-standard field dosimetry protocols new composite-field reference condition relative to the standard broad beam reference conditions. The TLD- and alanine-determined beam quality correction factors in the composite-field reference conditions were approximately 3% greater and differed by more than one standard deviation from the published TG-51 kQ values for all three chambers.

Suppression of E. multilocularis Hydatid Cysts after Ionizing Radiation Exposure

PubMed Central

Zhou, Rong; Zhang, Hong

2013-01-01

Background Heavy-ion therapy has an advantage over conventional radiotherapy due to its superb biological effectiveness and dose conformity in cancer therapy. It could be a potential alternate approach for hydatid cyst treatment. However, there is no information currently available on the cellular and molecular basis for heavy-ion irradiation induced cell death in cystic echinococcosis. Methododology/Principal Findings LD50 was scored by protoscolex death. Cellular and ultrastructural changes within the parasite were studied by light and electron microscopy, mitochondrial DNA (mtDNA) damage and copy number were measured by QPCR, and apoptosis was determined by caspase 3 expression and caspase 3 activity. Ionizing radiation induced sparse cytoplasm, disorganized and clumped organelles, large vacuoles and devoid of villi. The initial mtDNA damage caused by ionizing radiation increased in a dose-dependent manner. The kinetic of DNA repair was slower after carbon-ion radiation than that after X-rays radiation. High dose carbon-ion radiation caused irreversible mtDNA degradation. Cysts apoptosis was pronounced after radiation. Carbon-ion radiation was more effective to suppress hydatid cysts than X-rays. Conclusions These studies provide a framework to the evaluation of attenuation effect of heavy-ion radiation on cystic echinococcosis in vitro. Carbon-ion radiation is more effective to suppress E. multilocularis than X-rays. PMID:24205427

An optically stimulated luminescence system to measure dose profiles in x-ray computed tomography

NASA Astrophysics Data System (ADS)

Yukihara, E. G.; Ruan, C.; Gasparian, P. B. R.; Clouse, W. J.; Kalavagunta, C.; Ahmad, S.

2009-10-01

This paper describes an LED-based optically stimulated luminescence (OSL) system for dose profile measurements using OSL detector strips and investigates its performance in x-ray computed tomography (CT) dosimetry. To compensate for the energy response of the Al2O3:C OSL detectors, which have an effective atomic number of 11.28, field-specific energy correction factors were determined using two methods: (a) comparing the OSL profiles with ionization chamber point measurements (0.3 cm3 ionization chamber) and (b) comparing the OSL profiles integrated over a 100 mm length with 100 mm long pencil ionization chamber measurements. These correction factors were obtained for the CT body and head phantoms, central and peripheral positions and three x-ray tube potential differences (100 kVp, 120 kVp and 140 kVp). The OSL dose profiles corrected by the energy dependence agreed with the ionization chamber point measurements over the entire length of the phantom (300 mm). For 120 kVp x-ray tube potential difference, the CTDI100 values calculated using the OSL dose profiles corrected for the energy dependence and those obtained from an independent measurement with a 100 mm long pencil ionization chamber also agreed within ±5%.

A Compendium of Recent Optocoupler Radiation Test Data

NASA Technical Reports Server (NTRS)

Label, K. A.; Kniffin, S. D.; Reed, R. A.; Kim, H. S.; Wert, J. L.; Oberg, D. L.; Normand, E.; Johnston, A. H.; Lum, G. K.; Koga, R.;

Recent Total Ionizing Dose Results and Displacement Damage Results for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

Cochran, Donna J.; Buchner, Stephen P.; Irwin, Tim L.; LaBel, Kenneth A.; Marshall, Cheryl J.; Reed, Robert A.; Sanders, Anthony B.; Hawkins, Donald K.; Flanigan, Ryan J.; Cox, Stephen R.

2005-01-01

We present data on the vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage. Devices tested include optoelectronics, digital, analog, linear bipolar devices, hybrid devices, Analog-to- Digital Converters (ADCs), and Digital-to-Analog Converters (DACs), among others. T

Compendium of Single Event Effects, Total Ionizing Dose, and Displacement Damage for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

LaBel, Kenneth A.; O'Bryan, Martha V.; Chen, Dakai; Campola, Michael J.; Casey, Megan C.; Pellish, Jonathan A.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Ladbury, Raymond L.;

SU-F-T-293: Experimental Comparisons of Ionization Chambers with Different Volumes for CyberKnife Delivery Quality Assurance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakayama, M; Kobe University Graduate School of Medicine, Kobe, Hyogo; Munetomo, Y

2016-06-15

Purpose: To evaluate the practicality use of ionization chambers with different volumes for delivery quality assurance of CyberKnife plans, Methods: Dosimetric measurements with a spherical solid water phantom and three ionization chambers with volumes of 0.13, 0.04, and 0.01 cm3 (IBA CC13, CC04, and CC01, respectively) were performed for various CyberKnife clinical treatment plans including both isocentric and nonisocentric delivery. For each chamber, the ion recombination correction factors Ks were calculated using the Jaffe plot method and twovoltage method at a 10-cm depth for a 60-mm collimator field in a water phantom. The polarity correction factors Kpol were determined formore » 5–60-mm collimator fields in same experimental setup. The measured doses were compared to the doses for the detectors calculated using a treatment planning system. Results: The differences in the Ks between the Jaffe plot method and two-voltage method were −0.12, −0.02, and 0.89% for CC13, CC04, and CC01, respectively. The changes in Kpol for the different field sizes were 0.2, 0.3, and 0.8% for CC13, CC04, and CC01, respectively. The measured doses for CC04 and CC01 were within 3% of the calculated doses for the clinical treatment plans with isocentric delivery with collimator fields greater than 12.5 mm. Those for CC13 had differences of over 3% for the plans with isocentric delivery with collimator fields less than 15 mm. The differences for the isocentric plans were similar to those for the single beam plans. The measured doses for each chamber were within 3% of the calculated doses for the non-isocentric plans except for that with a PTV volume less than 1.0 cm{sup 3}. Conclusion: Although there are some limitations, the ionization chamber with a smaller volume is a better detector for verification of the CyberKnife plans owing to the high spatial resolution.« less

Atmospheric Gaseous Plasma with Large Dimensions

NASA Astrophysics Data System (ADS)

Korenev, Sergey

2012-10-01

The forming of atmospheric plasma with large dimensions using electrical discharge typically uses the Dielectric Barrier Discharge (DBD). The study of atmospheric DBD was shown some problems related to homogeneous volume plasma. The volume of this plasma determines by cross section and gas gap between electrode and dielectric. The using of electron beam for volume ionization of air molecules by CW relativistic electron beams was shown the high efficiency of this process [1, 2]. The main advantage of this approach consists in the ionization of gas molecules by electrons in longitudinal direction determines by their kinetic energy. A novel method for forming of atmospheric homogeneous plasma with large volume dimensions using ionization of gas molecules by pulsed non-relativistic electron beams is presented in the paper. The results of computer modeling for delivered doses of electron beams in gases and ionization are discussed. The structure of experimental bench with plasma diagnostics is considered. The preliminary results of forming atmospheric plasma with ionization gas molecules by pulsed nanosecond non-relativistic electron beam are given. The analysis of potential applications for atmospheric volume plasma is presented. Reference: [1] S. Korenev. ``The ionization of air by scanning relativistic high power CW electron beam,'' 2002 IEEE International Conference on Plasma Science. May 2002, Alberta, Canada. [2] S. Korenev, I. Korenev. ``The propagation of high power CW scanning electron beam in air.'' BEAMS 2002: 14th International Conference on High-Power Particle Beams, Albuquerque, New Mexico (USA), June 2002, AIP Conference Proceedings Vol. 650(1), pp. 373-376. December 17.

Ionizing radiation measurements on LDEF: A0015 Free flyer biostack experiment

NASA Technical Reports Server (NTRS)

Benton, E. V.; Frank, A. L.; Benton, E. R.; Csige, I.; Frigo, L. A.

1995-01-01

This report covers the analysis of passive radiation detectors flown as part of the A0015 Free Flyer Biostack on LDEF (Long Duration Exposure Facility). LET (linear energy transfer) spectra and track density measurements were made with CR-39 and Polycarbonate plastic nuclear track detectors. Measurements of total absorbed dose were carried out using Thermoluminescent Detectors. Thermal and resonance neutron dose equivalents were measured with LiF/CR-39 detectors. High energy neutron and proton dose equivalents were measured with fission foil/CR-39 detectors.

Evaluating analytical ionization quenching correction models for 3D liquid organic scintillator detector

NASA Astrophysics Data System (ADS)

Alsanea, F.; Beddar, S.

2017-05-01

Proton therapy offers dosimetric advantage over conventional photon therapy due to the finite range of the proton beam, which improves dose conformity. However, one of the main challenges of proton beam therapy is verification of the complex treatment plans delivered to a patient. Thus, 3D measurements are needed to verify the complex dose distribution. A 3D organic scintillator detector is capable of such measurements. However, organic scintillators exhibit a non-linear relation to the ionization density called ionization quenching. The ionization quenching phenomenon in organic scintillators must be accounted for to obtain accurate dose measurements. We investigated the energy deposition by secondary electrons (EDSE) model to explain ionization quenching in 3D liquid organic scintillator when exposed to proton beams. The EDSE model was applied to volumetric scintillation measurement of proton pencil beam with energies of 85.6, 100.9, 144.9 and 161.9 MeV. The quenching parameter in EDSE model ρq was determined by plotting the total light output vs the initial energy of the ion. The results were compared to the Birks semi-empirical formula of scintillation light emission.

Circulating Cytokine/Chemokine Concentrations Respond to Ionizing Radiation Doses but not Radiation Dose Rates: Granulocyte-Colony Stimulating Factor and Interleukin-18.

PubMed

Kiang, Juliann G; Smith, Joan T; Hegge, Sara R; Ossetrova, Natalia I

2018-06-01

Exposure to ionizing radiation is a crucial life-threatening factor in nuclear and radiological incidents. It is known that ionizing radiation affects cytokine/chemokine concentrations in the blood of B6D2F1 mice. It is not clear whether radiation dose rates would vary the physiological response. Therefore, in this study we utilized data from two experiments using B6D2F1 female mice exposed to six different dose rates ranging from low to high rates. In one experiment, mice received a total dose of 8 Gy (LD 0/30 ) of 60 Co gamma radiation at four dose rates: 0.04, 0.15, 0.30 and 0.47 Gy/min. Blood samples from mice were collected at 24 and 48 h postirradiation for cytokine/chemokine measurements, including interleukin (IL)-1β, IL-6, IL-10, keratinocyte cytokine (KC), IL-12p70, IL-15, IL-17A, IL-18, granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage (GM)-CSF, macrophage (M)-CSF, monokine induced by gamma interferon (MIG), tumor necrosis factor (TNF)-α, fibroblast growth factor (FGF)-basic, vascular endothelial growth factor (VEGF) and platelet-derived growth factor basic (PDGF-bb). At 24 h after ionizing irradiation at dose rate of 0.04 Gy/min, significant increases were observed only in G-CSF and M-CSF ( P < 0.05). At 0.15 Gy/min, IL-10, IL-17A, G-CSF and GM-CSF concentrations were increased. At 0.3 Gy/min, IL-15, IL-18, G-CSF, GM-CSF, M-CSF, MCP-1, MIP-2, MIG, FGF-basic, VEGF and PDGF-bb were significantly elevated ( P < 0.05). At 0.47 Gy/min, IL-6, KC, IL-10, MCP-1, G-CSF, GM-CSF and M-CSF were significantly increased. At 48 h postirradiation, all cytokines/chemokines except MCP-1 returned to or were below their baselines, suggesting these increases are transient at LD 0/30 irradiation. Of note, there is a limitation on day 2 because cytokines/chemokines are either at or below their baselines. Other parameters such as fms-like tyrosine kinase receptor-3 ligand (Flt-3 ligand) concentrations and lymphocyte counts, which have proven to be unaffected by radiation dose rates, can be used instead for assessing the radiation dose. However, in a separate radiation dose and time-course experiment, increases in IL-18 and G-CSF depended on the radiation doses but showed no significant differences between 0.58 and 1.94 Gy/min ( P > 0.05) at 3 and 6 Gy but not 12 Gy. G-CSF continued to increase up to day 7, whereas IL-18 increased on day 4 and remained above baseline level on day 7. Therefore, time after irradiation at different doses should be taken into consideration. To our knowledge, these results are the first to suggest that ionizing radiation, even at a very low-dose-rate (0.04 Gy/min), induces circulating G-CSF increases but not others for selected time points; radiation-induced increases in IL-18 at radiation dose rates between 0.15 and 1.94 Gy/min are also not in a radiation dose-rate-dependent manner. C-CSF, lymphocyte counts and circulating Flt-3 ligand should be explored further as possible biomarkers of radiation exposure at early time points. IL-18 is also worthy of further study as a potential biomarker at later time points.

A new model for volume recombination in plane-parallel chambers in pulsed fields of high dose-per-pulse

NASA Astrophysics Data System (ADS)

Gotz, M.; Karsch, L.; Pawelke, J.

2017-11-01

In order to describe the volume recombination in a pulsed radiation field of high dose-per-pulse this study presents a numerical solution of a 1D transport model of the liberated charges in a plane-parallel ionization chamber. In addition, measurements were performed on an Advanced Markus ionization chamber in a pulsed electron beam to obtain suitable data to test the calculation. The experiment used radiation pulses of 4 μs duration and variable dose-per-pulse values up to about 1 Gy, as well as pulses of variable duration up to 308 μs at constant dose-per-pulse values between 85 mGy and 400 mGy. Those experimental data were compared to the developed numerical model and existing descriptions of volume recombination. At low collection voltages the observed dose-per-pulse dependence of volume recombination can be approximated by the existing theory using effective parameters. However, at high collection voltages large discrepancies are observed. The developed numerical model shows much better agreement with the observations and is able to replicate the observed behavior over the entire range of dose-per-pulse values and collection voltages. Using the developed numerical model, the differences between observation and existing theory are shown to be the result of a large fraction of the charge being collected as free electrons and the resultant distortion of the electric field inside the chamber. Furthermore, the numerical solution is able to calculate recombination losses for arbitrary pulse durations in good agreement with the experimental data, an aspect not covered by current theory. Overall, the presented numerical solution of the charge transport model should provide a more flexible tool to describe volume recombination for high dose-per-pulse values as well as for arbitrary pulse durations and repetition rates.

A new model for volume recombination in plane-parallel chambers in pulsed fields of high dose-per-pulse.

PubMed

Gotz, M; Karsch, L; Pawelke, J

2017-11-01

In order to describe the volume recombination in a pulsed radiation field of high dose-per-pulse this study presents a numerical solution of a 1D transport model of the liberated charges in a plane-parallel ionization chamber. In addition, measurements were performed on an Advanced Markus ionization chamber in a pulsed electron beam to obtain suitable data to test the calculation. The experiment used radiation pulses of 4 μs duration and variable dose-per-pulse values up to about 1 Gy, as well as pulses of variable duration up to 308 [Formula: see text] at constant dose-per-pulse values between 85 mGy and 400 mGy. Those experimental data were compared to the developed numerical model and existing descriptions of volume recombination. At low collection voltages the observed dose-per-pulse dependence of volume recombination can be approximated by the existing theory using effective parameters. However, at high collection voltages large discrepancies are observed. The developed numerical model shows much better agreement with the observations and is able to replicate the observed behavior over the entire range of dose-per-pulse values and collection voltages. Using the developed numerical model, the differences between observation and existing theory are shown to be the result of a large fraction of the charge being collected as free electrons and the resultant distortion of the electric field inside the chamber. Furthermore, the numerical solution is able to calculate recombination losses for arbitrary pulse durations in good agreement with the experimental data, an aspect not covered by current theory. Overall, the presented numerical solution of the charge transport model should provide a more flexible tool to describe volume recombination for high dose-per-pulse values as well as for arbitrary pulse durations and repetition rates.

A comparison of two methods of in vivo dosimetry for a high energy neutron beam.

PubMed

Blake, S W; Bonnett, D E; Finch, J

1990-06-01

Two methods of in vivo dosimetry have been compared in a high energy neutron beam. These were activation dosimetry and thermoluminescence dosimetry (TLD). Their suitability was determined by comparison with estimates of total dose, obtained using a tissue equivalent ionization chamber. Measurements were made on the central axis and a profile of a 10 x 10 cm square field and also behind a shielding block in order to simulate conditions of clinical use. The TLD system was found to provide the best estimate of total dose.

SU-F-T-174: Patient-Specific Point Dose Measurement Using Fiber Optic Radiation Sensor Using Cerenkov Radiation for Proton Therapeutic Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Son, J; National Cancer Center, Goyang-si; Kim, M

Purpose: A fiber-optic radiation sensor using Cerenkov radiation (FOCR) has been widely studied for use as a dosimeter for proton therapeutic beam. We developed the FOCR, and it applied to patient-specific point dose measurement in order to evaluate the effectiveness of the FOCR system for proton therapy QA. Methods: Calibration of FOCR was performed with an ionization chamber whose absolute doses were determined according to the IAEA TRS-398 protocol. To determine the calibration curve, the FOCR was irradiated perpendicularly to the proton beam at the 13 dose levels steps. We selected five actual patient treatment plans performed at proton therapymore » center and compared the resulting FOCR measurements with the ionization chamber measurements. Results: The Cerenkov light yield of the FOCR increases linearly with as the dose measured using the ionization chamber increases from 0 cGy to 500 cGy. The results indicate that the fitting curve is linear, suggesting that dose measurement based on the light yield of the FOCR is possible. The results of proton radiation dose QA performed using the FOCR for 10 proton fields and five patients are good agreement with an ionization chamber. Conclusion: We carried out the patient QA using the FOCR for proton therapeutic beam and evaluated the effectiveness of the FOCR as a proton therapy QA tool. Our results indicate that the FOCR is suitable for use in patient QA of clinical proton beams.« less

Terrestrial effects of high energy cosmic rays

NASA Astrophysics Data System (ADS)

Atri, Dimitra

On geological timescales, the Earth is likely to be exposed to higher than the usual flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere, initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles and photons. Increased ionization leads to changes in atmospheric chemistry, resulting in ozone depletion. This increases the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit, which could enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of hadronic interactions of the primary cosmic rays with the atmosphere are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates the radiation dose from cosmic rays causing damage to DNA and an increase in mutation rates and cancer, which can have serious biological implications for surface and sub-surface life. Using CORSIKA, we perform massive computer simulations and construct lookup tables for 10 GeV - 1 PeV primaries, which can be used to quantify these effects from enhanced cosmic ray exposure to any astrophysical source. These tables are freely available to the community and can be used for other studies. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. Increased radiation dose from muons could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

Terrestrial Effects of High Energy Cosmic Rays

NASA Astrophysics Data System (ADS)

Atri, Dimitra

2011-01-01

On geological timescales, the Earth is likely to be exposed to an increased flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles. Increased ionization could lead to changes in atmospheric chemistry, resulting in ozone depletion. This could increase the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit can could possibly enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of nuclear interactions are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates radiation dose from cosmic rays causing DNA damage and increase in the mutation rates, which can have serious biological implications for terrestrial and sub-terrestrial life. This radiation dose is an important constraint on the habitability of a planet. Using CORSIKA, we perform massive computer simulations and construct lookup tables from 10 GeV - 1 PeV primaries (1 PeV - 0.1 ZeV in progress), which can be used to quantify these effects. These tables are freely available to the community and can be used for other studies, not necessarily relevant to Astrobiology. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. This could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

Ionizing radiation and autoimmunity: Induction of autoimmune disease in mice by high dose fractionated total lymphoid irradiation and its prevention by inoculating normal T cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakaguchi, N.; Sakaguchi, S.; Miyai, K.

1992-11-01

Ionizing radiation can functionally alter the immune system and break self-tolerance. High dose (42.5 Gy), fractionated (2.5 Gy 17 times) total lymphoid irradiation (TLI) on mice caused various organ-specific autoimmune diseases, such as gastritis, thyroiditis, and orchitis, depending on the radiation dosages, the extent of lymphoid irradiation, and the genetic background of the mouse strains. Radiation-induced tissue damage is not the primary cause of the autoimmune disease because irradiation of the target organs alone failed to elicit the autoimmunity and shielding of the organs from irradiation was unable to prevent it. In contrast, irradiation of both the thymus and themore » peripheral lymphoid organs/tissues was required for efficient induction of autoimmune disease by TLI. TLI eliminated the majority of mature thymocytes and the peripheral T cells for 1 mo, and inoculation of spleen cell, thymocyte, or bone marrow cell suspensions (prepared from syngeneic nonirradiated mice) within 2 wk after TLI effectively prevented the autoimmune development. Depletion of T cells from the inocula abrogated the preventive activity. CD4[sup +] T cells mediated the autoimmune prevention but CD8[sup +] T cells did not. CD4[sup +] T cells also appeared to mediate the TLI-induced autoimmune disease because CD4[sup +] T cells from disease-bearing TLI mice adoptively transferred the autoimmune disease to syngeneic naive mice. Taken together, these results indicate that high dose, fractionated ionizing radiation on the lymphoid organs/tissues can cause autoimmune disease by affecting the T cell immune system, rather than the target self-Ags, presumably by altering T cell-dependent control of self-reactive T cells. 62 refs., 9 figs., 2 tabs.« less

The skin: its structure and response to ionizing radiation.

PubMed

Hopewell, J W

1990-04-01

The response of the skin to ionizing radiation has important implications both for the treatment of malignant disease by radiation and for radiological protection. The structural organization of human skin is described and compared with that of the pig, with which it shows many similarities, in order that the response of the skin to ionizing radiation may be more fully understood. Acute radiation damage to the skin is primarily a consequence of changes in the epidermis; the timing of the peak of the reaction is related to the kinetic organization of this layer. The rate of development of damage is independent of the radiation dose, since this is related to the natural rate of loss of cells from the basal layer of the epidermis. Recovery of the epidermis occurs as a result of the proliferation of surviving clonogenic basal cells from within the irradiated area. The presence of clonogenic cells in the canal of the hair follicle is important, particularly after non-uniform irradiation from intermediate energy beta-emitters. The migration of viable cells from the edges of the irradiated site is also significant when small areas of skin are irradiated. Late damage to the skin is primarily a function of radiation effects on the vasculature; this produces a wave of dermal atrophy after 16-26 weeks. Dermal necrosis develops at this time after high doses. A second phase of dermal thinning is seen to develop after greater than 52 weeks, and this later phase of damage is associated with the appearance of telangiectasia. Highly localized irradiation of the skin, either to a specific layer (as may result from exposure to very low energy beta-emitters) or after exposure to small highly radioactive particles, 'hot particles', produces gross effects that become visibly manifest within 2 weeks of exposure. These changes result from the direct killing of the cells of the skin in interphase after doses greater than 100 Gy. Dose-effect curves have been established for the majority of these deterministic endpoints in the skin from the results of both experimental and clinical studies. These are of value in the establishment of safe radiation dose limits for the skin.

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroll, Florian; Karsch, Leonhard; Pawelke, Jörg

2013-08-15

Purpose: Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-termmore » stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time.Methods: A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators.Results: Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account, determined dose profiles are in agreement with reference measurements. An inherent drawback of the scintillator is the nonlinear light output for high stopping-power radiation due to the quenching effect. It impacts the depth dose curves measured with the dosimeter. For single Bragg peak distributions this leads to a peak to plateau ratio of 2.8 instead of 4.5 for the reference ionization chamber measurement. Furthermore, the transmission of the clinical bremsstrahlung beams through the scintillator leads to the saturation of one camera, making dose reconstructions in that case presently not feasible.Conclusions: It is shown that distributions of scintillation light generated by proton or electron beams can be reconstructed by the dosimetry system within minutes. The quenching apparent for proton irradiation, and the yet not precisely determined position dependency of the imaging scale, require further investigation and corrections. Upgrading the prototype with larger or inorganic scintillators would increase the detectable proton and electron energy range. The presented results show that the determination of 3D dose distributions using scintillator blocks and optical tomography is a promising dosimetry method.« less

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography.

PubMed

Kroll, Florian; Pawelke, Jörg; Karsch, Leonhard

2013-08-01

Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-term stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time. A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators. Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account, determined dose profiles are in agreement with reference measurements. An inherent drawback of the scintillator is the nonlinear light output for high stopping-power radiation due to the quenching effect. It impacts the depth dose curves measured with the dosimeter. For single Bragg peak distributions this leads to a peak to plateau ratio of 2.8 instead of 4.5 for the reference ionization chamber measurement. Furthermore, the transmission of the clinical bremsstrahlung beams through the scintillator leads to the saturation of one camera, making dose reconstructions in that case presently not feasible. It is shown that distributions of scintillation light generated by proton or electron beams can be reconstructed by the dosimetry system within minutes. The quenching apparent for proton irradiation, and the yet not precisely determined position dependency of the imaging scale, require further investigation and corrections. Upgrading the prototype with larger or inorganic scintillators would increase the detectable proton and electron energy range. The presented results show that the determination of 3D dose distributions using scintillator blocks and optical tomography is a promising dosimetry method.

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

NASA Astrophysics Data System (ADS)

Vaz, Pedro

2014-11-01

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.

Preventive or Potential Therapeutic Value of Nutraceuticals against Ionizing Radiation-Induced Oxidative Stress in Exposed Subjects and Frequent Fliers

PubMed Central

Giardi, Maria Teresa; Touloupakis, Eleftherios; Bertolotto, Delfina; Mascetti, Gabriele

2013-01-01

Humans are constantly exposed to ionizing radiation deriving from outer space sources or activities related to medical care. Absorption of ionizing radiation doses over a prolonged period of time can result in oxidative damage and cellular dysfunction inducing several diseases, especially in ageing subjects. In this report, we analyze the effects of ionizing radiation, particularly at low doses, in relation to a variety of human pathologies, including cancer, and cardiovascular and retinal diseases. We discuss scientific data in support of protection strategies by safe antioxidant formulations that can provide preventive or potential therapeutic value in response to long-term diseases that may develop following exposure. PMID:23965979

Radiation Gene-expression Signatures in Primary Breast Cancer Cells.

PubMed

Minafra, Luigi; Bravatà, Valentina; Cammarata, Francesco P; Russo, Giorgio; Gilardi, Maria C; Forte, Giusi I

2018-05-01

In breast cancer (BC) care, radiation therapy (RT) is an efficient treatment to control localized tumor. Radiobiological research is needed to understand molecular differences that affect radiosensitivity of different tumor subtypes and the response variability. The aim of this study was to analyze gene expression profiling (GEP) in primary BC cells following irradiation with doses of 9 Gy and 23 Gy delivered by intraoperative electron radiation therapy (IOERT) in order to define gene signatures of response to high doses of ionizing radiation. We performed GEP by cDNA microarrays and evaluated cell survival after IOERT treatment in primary BC cell cultures. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to validate candidate genes. We showed, for the first time, a 4-gene and a 6-gene signature, as new molecular biomarkers, in two primary BC cell cultures after exposure at 9 Gy and 23 Gy respectively, for which we observed a significantly high survival rate. Gene signatures activated by different doses of ionizing radiation may predict response to RT and contribute to defining a personalized biological-driven treatment plan. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Determination of bisphenol AF (BPAF) in tissues, serum, urine and feces of orally dosed rats by ultra-high-pressure liquid chromatography-electrospray tandem mass spectrometry.

PubMed

Yang, Yunjia; Yin, Jie; Yang, Yi; Zhou, Naiyuan; Zhang, Jing; Shao, Bing; Wu, Yongning

2012-07-15

As a homologue of bisphenol A (BPA), there is concern about the potential reproductive and developmental toxicity of bisphenol AF (BPAF) based on in vitro tests. In this study, a simple and universal analytical method was developed for the determination of trace BPAF in various tissues and excreta of rats after they were orally dosed. The samples were hydrolyzed with glucuronidase/arylsulfatase followed by ultrasonic extraction with acetonitrile. The crude extract was purified with a mixed-mode anion exchange (Oasis MAX) solid-phase extraction (SPE) cartridge. Separation and quantification was then conducted by ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in negative ionization mode. The recoveries at three fortification levels in different biological samples were from 71.0% to 102.3% with relative standard deviations no more than 13.2% (n=6). The quantification limits of the method were from 0.5 μg/kg to 3 μg/kg depending on the matrix. This method was successfully applied to the determination of BPAF in tissues, serum, urine and feces of orally dosed rats. Copyright © 2012 Elsevier B.V. All rights reserved.

Evaluation of characteristics of high-energy electron beams using N-isopropyl-acrylamide gel dosimeter

NASA Astrophysics Data System (ADS)

Shih, Tian-Yu; Yen, Tsung-Hsien; Liu, Yan-Lin; Luzhbin, Dmytro; Wu, Jay

2017-11-01

The advantage of electron beam radiotherapy is that the absorbed dose rapidly decreases with the increasing depth, which can prevent damage to deeper organs and tissues. Accurately evaluating the absorbed dose in the superficial tumor is imperative. This study assessed the characteristics of electron beams by using the N-isopropyl-acrylamide (n-NIPAM) gel dosimeter. The n-NIPAM gel was composed of 6% gelatin, 5% monomer, and 2.5% cross-linker with 5 mM tetrakis (hydroxymethyl) phosphonium chloride for deoxygenation. The gel was irradiated with 6-, 9-, and 12-MeV electron beams with dose rates of 100-600 MU/min, respectively. The energy dependence and dose rate dependence were assessed. The beam profiles and percentage depth doses were measured and compared with the results of the Gafchromic film and ionization chamber. The linearity of the n-NIPAM gel under 6-, 9-, and 12-MeV electrons was larger than 0.990 with 2% variation in sensitivity. The sensitivity of the gel under 100-600 MU/min showed 5% variations. The energy and dose rate dependence can be negligible. The beam profiles and percentage depth doses measured by the n-NIPAM gel matched well with the results of the ionization chamber and film. This study reveals the possibility of using the n-NIPAM gel dosimeter for electron beam measurements in clinical radiotherapy.

Evoked bioelectrical brain activity following exposure to ionizing radiation.

PubMed

Loganovsky, K; Kuts, K

2017-12-01

The article provides an overview of modern physiological evidence to support the hypothesis on cortico limbic sys tem dysfunction due to the hippocampal neurogenesis impairment as a basis of the brain interhemispheric asym metry and neurocognitive deficit after radiation exposure. The importance of the research of both evoked poten tials and fields as a highly sensitive and informative method is emphasized.Particular attention is paid to cerebral sensor systems dysfunction as a typical effect of ionizing radiation. Changes in functioning of the central parts of sensory analyzers of different modalities as well as the violation of brain integrative information processes under the influence of small doses of ionizing radiation can be critical when determining the radiation risks of space flight. The possible long term prospects for manned flights into space, including to Mars, given the effects identified are discussed. Potential risks to the central nervous system during space travel comprise cognitive functions impairment, including the volume of short term memory short ening, impaired motor functions, behavioral changes that could affect human performance and health. The remote risks for CNS are considered to be the following possible neuropsychiatric disorders: accelerated brain aging, Alzheimer's disease and other types of dementia. The new radiocerebral dose dependent effect, when applied cog nitive auditory evoked potentials P300 technique with a possible threshold dose of 0.05 Gy, manifesting in a form of disruption of information processing in the Wernicke's area is under discussion. In order to identify neurophys iological biological markers of ionizing radiation further international researches with adequate dosimetry support are necessary. K. Loganovsky, K. Kuts.

Quantitative Proteomic Profiling of Low-Dose Ionizing Radiation Effects in a Human Skin Model

PubMed Central

Hengel, Shawna M.; Aldrich, Joshua T.; Waters, Katrina M.; Pasa-Tolic, Ljiljana; Stenoien, David L.

2014-01-01

To assess responses to low-dose ionizing radiation (LD-IR) exposures potentially encountered during medical diagnostic procedures, nuclear accidents or terrorist acts, a quantitative proteomic approach was used to identify changes in protein abundance in a reconstituted human skin tissue model treated with 0.1 Gy of ionizing radiation. To improve the dynamic range of the assay, subcellular fractionation was employed to remove highly abundant structural proteins and to provide insight into radiation-induced alterations in protein localization. Relative peptide quantification across cellular fractions, control and irradiated samples was performing using 8-plex iTRAQ labeling followed by online two-dimensional nano-scale liquid chromatography and high resolution MS/MS analysis. A total of 107 proteins were detected with statistically significant radiation-induced change in abundance (>1.5 fold) and/or subcellular localization compared to controls. The top biological pathways identified using bioinformatics include organ development, anatomical structure formation and the regulation of actin cytoskeleton. From the proteomic data, a change in proteolytic processing and subcellular localization of the skin barrier protein, filaggrin, was identified, and the results were confirmed by western blotting. This data indicate post-transcriptional regulation of protein abundance, localization and proteolytic processing playing an important role in regulating radiation response in human tissues. PMID:28250387

[Dose rate-dependent cellular and molecular effects of ionizing radiation].

PubMed

Przybyszewski, Waldemar M; Wideł, Maria; Szurko, Agnieszka; Maniakowski, Zbigniew

2008-09-11

The aim of radiation therapy is to kill tumor cells while minimizing damage to normal cells. The ultimate effect of radiation can be apoptotic or necrotic cell death as well as cytogenetic damage resulting in genetic instability and/or cell death. The destructive effects of radiation arise from direct and indirect ionization events leading to peroxidation of macromolecules, especially those present in lipid-rich membrane structures as well as chromatin lipids. Lipid peroxidative end-products may damage DNA and proteins. A characteristic feature of radiation-induced peroxidation is an inverse dose-rate effect (IDRE), defined as an increase in the degree of oxidation(at constant absorbed dose) accompanying a lower dose rate. On the other hand, a low dose rate can lead to the accumulation of cells in G2, the radiosensitive phase of the cell cycle since cell cycle control points are not sensitive to low dose rates. Radiation dose rate may potentially be the main factor improving radiotherapy efficacy as well as affecting the intensity of normal tissue and whole-body side effects. A better understanding of dose rate-dependent biological effects may lead to improved therapeutic intervention and limit normal tissue reaction. The study reviews basic biological effects that depend on the dose rate of ionizing radiation.

Transit dosimetry in IMRT with an a-Si EPID in direct detection configuration

NASA Astrophysics Data System (ADS)

Sabet, Mahsheed; Rowshanfarzad, Pejman; Vial, Philip; Menk, Frederick W.; Greer, Peter B.

2012-08-01

In this study an amorphous silicon electronic portal imaging device (a-Si EPID) converted to direct detection configuration was investigated as a transit dosimeter for intensity modulated radiation therapy (IMRT). After calibration to dose and correction for a background offset signal, the EPID-measured absolute IMRT transit doses for 29 fields were compared to a MatriXX two-dimensional array of ionization chambers (as reference) using Gamma evaluation (3%, 3 mm). The MatriXX was first evaluated as reference for transit dosimetry. The accuracy of EPID measurements was also investigated by comparison of point dose measurements by an ionization chamber on the central axis with slab and anthropomorphic phantoms in a range of simple to complex fields. The uncertainty in ionization chamber measurements in IMRT fields was also investigated by its displacement from the central axis and comparison with the central axis measurements. Comparison of the absolute doses measured by the EPID and MatriXX with slab phantoms in IMRT fields showed that on average 96.4% and 97.5% of points had a Gamma index<1 in head and neck and prostate fields, respectively. For absolute dose comparisons with anthropomorphic phantoms, the values changed to an average of 93.6%, 93.7% and 94.4% of points with Gamma index<1 in head and neck, brain and prostate fields, respectively. Point doses measured by the EPID and ionization chamber were within 3% difference for all conditions. The deviations introduced in the response of the ionization chamber in IMRT fields were<1%. The direct EPID performance for transit dosimetry showed that it has the potential to perform accurate, efficient and comprehensive in vivo dosimetry for IMRT.

Practical use of a plastic scintillator for quality assurance of electron beam therapy.

PubMed

Yogo, Katsunori; Tatsuno, Yuya; Tsuneda, Masato; Aono, Yuki; Mochizuki, Daiki; Fujisawa, Yoshiki; Matsushita, Akihiro; Ishigami, Minoru; Ishiyama, Hiromichi; Hayakawa, Kazushige

2017-06-07

Quality assurance (QA) of clinical electron beams is essential for performing accurate and safe radiation therapy. However, with advances in radiation therapy, QA has become increasingly labor-intensive and time-consuming. In this paper, we propose a tissue-equivalent plastic scintillator for quick and easy QA of clinical electron beams. The proposed tool comprises a plastic scintillator plate and a charge-coupled device camera that enable the scintillation light by electron beams to be recorded with high sensitivity and high spatial resolution. Further, the Cerenkov image is directly subtracted from the scintillation image to discriminate Cerenkov emissions and accurately measure the dose profiles of electron beams with high spatial resolution. Compared with conventional methods, discrepancies in the depth profile improved from 7% to 2% in the buildup region via subtractive corrections. Further, the output brightness showed good linearity with dose, good reproducibility (deviations below 1%), and dose rate independence (within 0.5%). The depth of 50% dose measured with the tool, an index of electron beam quality, was within  ±0.5 mm of that obtained with an ionization chamber. Lateral brightness profiles agreed with the lateral dose profiles to within 4% and no significant improvement was obtained using Cerenkov corrections. Field size agreed to within 0.5 mm with those obtained with ionization chamber. For clinical QA of electron boost treatment, a disk scintillator that mimics the shape of a patient's breast is applied. The brightness distribution and dose, calculated using a treatment planning system, was generally acceptable for clinical use, except in limited zones. Overall, the proposed plastic scintillator plate tool efficiently performs QA for electron beam therapy and enables simultaneous verification of output constancy, beam quality, depth, and lateral dose profiles during monthly QAs at lower doses of irradiation (small monitor units, MUs).

Evaluation of low-dose irradiation on microbiological quality of white carrots and string beans

NASA Astrophysics Data System (ADS)

Koike, Amanda C. R.; Santillo, Amanda G.; Rodrigues, Flávio T.; Duarte, Renato C.; Villavicencio, Anna Lucia C. H.

2012-08-01

The minimally processed food provided the consumer with a product quality, safety and practicality. However, minimal processing of food does not reduce pathogenic population of microorganisms to safe levels. Ionizing radiation used in low doses is effective to maintain the quality of food, reducing the microbiological load but rather compromising the nutritional values and sensory property. The association of minimal processing with irradiation could improve the quality and safety of product. The purpose of this study was to evaluate the effectiveness of low-doses of ionizing radiation on the reduction of microorganisms in minimally processed foods. The results show that the ionizing radiation of minimally processed vegetables could decontaminate them without several changes in its properties.

Role of genetic background in induced instability

NASA Technical Reports Server (NTRS)

Kadhim, Munira A.; Nelson, G. A. (Principal Investigator)

2003-01-01

Genomic instability is effectively induced by ionizing radiation. Recently, evidence has accumulated supporting a relationship between genetic background and the radiation-induced genomic instability phenotype. This is possibly due to alterations in proteins responsible for maintenance of genomic integrity or altered oxidative metabolism. Studies in human cell lines, human primary cells, and mouse models have been performed predominantly using high linear energy transfer (LET) radiation, or high doses of low LET radiation. The interplay between genetics, radiation response, and genomic instability has not been fully determined at low doses of low LET radiation. However, recent studies using low doses of low LET radiation suggest that the relationship between genetic background and radiation-induced genomic instability may be more complicated than these same relationships at high LET or high doses of low LET radiation. The complexity of this relationship at low doses of low LET radiation suggests that more of the population may be at risk than previously recognized and may have implications for radiation risk assessment.

SU-E-T-184: Clinical VMAT QA Practice Using LINAC Delivery Log Files

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnston, H; Jacobson, T; Gu, X

2015-06-15

Purpose: To evaluate the accuracy of volumetric modulated arc therapy (VMAT) treatment delivery dose clouds by comparing linac log data to doses measured using an ionization chamber and film. Methods: A commercial IMRT quality assurance (QA) process utilizing a DICOM-RT framework was tested for clinical practice using 30 prostate and 30 head and neck VMAT plans. Delivered 3D VMAT dose distributions were independently checked using a PinPoint ionization chamber and radiographic film in a solid water phantom. DICOM RT coordinates were used to extract the corresponding point and planar doses from 3D log file dose distributions. Point doses were evaluatedmore » by computing the percent error between log file and chamber measured values. A planar dose evaluation was performed for each plan using a 2D gamma analysis with 3% global dose difference and 3 mm isodose point distance criteria. The same analysis was performed to compare treatment planning system (TPS) doses to measured values to establish a baseline assessment of agreement. Results: The mean percent error between log file and ionization chamber dose was 1.0%±2.1% for prostate VMAT plans and −0.2%±1.4% for head and neck plans. The corresponding TPS calculated and measured ionization chamber values agree within 1.7%±1.6%. The average 2D gamma passing rates for the log file comparison to film are 98.8%±1.0% and 96.2%±4.2% for the prostate and head and neck plans, respectively. The corresponding passing rates for the TPS comparison to film are 99.4%±0.5% and 93.9%±5.1%. Overall, the point dose and film data indicate that log file determined doses are in excellent agreement with measured values. Conclusion: Clinical VMAT QA practice using LINAC treatment log files is a fast and reliable method for patient-specific plan evaluation.« less

Ionizing radiation induces O6-alkylguanine-DNA-alkyltransferase mRNA and activity in mouse tissues.

PubMed

Wilson, R E; Hoey, B; Margison, G P

1993-04-01

The effect of exposure to whole-body gamma-irradiation or fast electrons on O6-alkylguanine-DNA-alkyltransferase (ATase) activity and mRNA abundance has been examined in mice. In response to gamma-radiation, hepatic ATase activity was significantly raised in BDF1 mice 24 h post-irradiation, reaching a maximum of 2- to 3-fold at 36 h and beginning to decrease by 48-60 h. A small but consistently higher level of induction was achieved when mice were exposed using a low dose rate (0.015 Gy/min) compared to a high dose rate (0.5 Gy/min). ATase activity was also induced approximately 2-fold 48 h post-irradiation in brain, kidney, lung and spleen, with a greater induction again observed in response to the lower dose rate. In response to fast electrons from a linear accelerator hepatic ATase activity was also induced 2- to 3-fold 48 h post-irradiation in BDF1, BALB/c, C57Bl and DBA2 strains. Induction of ATase activity in livers of BDF1 mice was observed 48 h after a total single dose of 5 Gy gamma-radiation (2-fold), increasing to a slightly higher level at 15 Gy, but no induction was observed at doses of 2 Gy and below. Although a maximum 2- to 3-fold induction of ATase activity was observed, mRNA levels were induced 3- to 4-fold by 48 h after a dose of 15 Gy. Furthermore, significant increases in mRNA levels were detected at low doses (1-2 Gy) at which there was no apparent increase in ATase activity. This suggests that ionizing radiation increases ATase levels by a process involving transcriptional upregulation but that strong post-transcriptional and/or translational controls operate to limit induction of enzyme activity to 2- to 3-fold. This is the first report of an in vivo induction of ATase by ionizing radiation in a species other than the rat.

Electron irradiation induced phase separation in a sodium borosilicate glass

NASA Astrophysics Data System (ADS)

Sun, K.; Wang, L. M.; Ewing, R. C.; Weber, W. J.

2004-06-01

Electron irradiation induced phase separation in a sodium borosilicate glass was studied in situ by analytical electron microscopy. Distinctly separate phases that are rich in boron and silicon formed at electron doses higher than 4.0 × 10 11 Gy during irradiation. The separated phases are still in amorphous states even at a much high dose (2.1 × 10 12 Gy). It indicates that most silicon atoms remain tetrahedrally coordinated in the glass during the entire irradiation period, except some possible reduction to amorphous silicon. The particulate B-rich phase that formed at high dose was identified as amorphous boron that may contain some oxygen. Both ballistic and ionization processes may contribute to the phase separation.

Solid state neutron dosimeter for space applications

NASA Technical Reports Server (NTRS)

Entine, Gerald; Nagargar, Vivek; Sharif, Daud

1990-01-01

Personnel engaged in space flight are exposed to significant flux of high energy neutrons arising from both primary and secondary sources of ionizing radiation. Presently, there exist no compact neutron sensor capable of being integrated in a flight instrument to provide real time measurement of this radiation flux. A proposal was made to construct such an instrument using special PIN silicon diode which has the property of being insensitive to the other forms of ionizing radiation. Studies were performed to determine the design and construction of a better reading system to allow the PIN diode to be read with high precision. The physics of the device was studied, especially with respect to those factors which affect the sensitivity and reproducibility of the neutron response. This information was then used to develop methods to achieve high sensitivity at low neutron doses. The feasibility was shown of enhancing the PIN diode sensitivity to make possible the measurement of the low doses of neutrons encountered in space flights. The new PIN diode will make possible the development of a very compact, accurate, personal neutron dosimeter.

Evaluation of commercial ADC radiation tolerance for accelerator experiments

DOE PAGES

Chen, K.; Chen, H.; Kierstead, J.; ...

2015-08-17

Electronic components used in high energy physics experiments are subjected to a radiation background composed of high energy hadrons, mesons and photons. These particles can induce permanent and transient effects that affect the normal device operation. Ionizing dose and displacement damage can cause chronic damage which disable the device permanently. Transient effects or single event effects are in general recoverable with time intervals that depend on the nature of the failure. The magnitude of these effects is technology dependent with feature size being one of the key parameters. Analog to digital converters are components that are frequently used in detectormore » front end electronics, generally placed as close as possible to the sensing elements to maximize signal fidelity. We report on radiation effects tests conducted on 17 commercially available analog to digital converters and extensive single event effect measurements on specific twelve and fourteen bit ADCs that presented high tolerance to ionizing dose. We discuss mitigation strategies for single event effects (SEE) for their use in the large hadron collider environment.« less

Comparison of absorbed-dose-to-water units for Co-60 and high-energy x-rays between PTB and LNE-LNHB

NASA Astrophysics Data System (ADS)

Delaunay, F.; Kapsch, R.-P.; Gouriou, J.; Illemann, J.; Krauss, A.; Le Roy, M.; Ostrowsky, A.; Sommier, L.; Vermesse, D.

2012-10-01

During the Euramet project JRP7 ‘External Beam Cancer Therapy’, PTB and LNE-LNHB used primary standards to determine the absorbed dose to water under IMRT conditions (in small fields). PTB used a water calorimeter to determine the absorbed-dose-to-water references in 6 MV and 10 MV beams for field sizes of 10 cm × 10 cm and 3 cm × 3 cm while LNE-LNHB used graphite calorimeters in 6 MV and 12 MV beams for field sizes of 10 cm × 10 cm, 4 cm × 4 cm and 2 cm × 2 cm. The purpose of this study is to compare PTB and LNE-LNHB new absorbed-dose-to-water references. LNE-LNHB sent an Exradin A1SL ionization chamber traceable to its primary standard to the PTB for calibration in 60Co and in linac beams and PTB sent a PTW 31010 ionization chamber traceable to its primary standard to LNE-LNHB for calibration in 60Co and in linac beams. Calculated Sw,air will be used as beam quality specifier for the ionization chamber comparison at different field sizes. The standard uncertainties (k = 1) of PTB and LNE-LNHB calibration coefficients lie respectively between 0.25% (60Co) and 0.40% (linac) and between 0.29% and 0.46%. PTB and LNE-LNHB absorbed-dose-to-water references developed for this project, based respectively on water calorimetry and on graphite calorimetry, agree within 1.5 standard deviations for field size of 10 cm × 10 cm down to 2 cm × 2 cm and for beams of 6 MV to 10 MV.

Feasibility of using two-dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry.

PubMed

Chung, Heeteak; Li, Jonathan; Samant, Sanjiv

2011-04-08

Two-dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from -0.2% ~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry.

Ionizing radiation exposure as a result of diagnostic imaging in patients with lymphoma.

PubMed

Crowley, M P; O'Neill, S B; Kevane, B; O'Neill, D C; Eustace, J A; Cahill, M R; Bird, B; Maher, M M; O'Regan, K; O'Shea, D

2016-05-01

Survival rates among patients with lymphoma continue to improve. Strategies aimed at reducing potential treatment-related toxicity are increasingly prioritized. While radiological procedures play an important role, ionizing radiation exposure has been linked to an increased risk of malignancy, particularly among individuals whose cumulative radiation exposure exceeds a specific threshold (75 millisieverts). Within this retrospective study, the cumulative radiation exposure dose was quantified for 486 consecutive patients with lymphoma. The median estimated total cumulative effective dose (CED) of ionizing radiation per subject was 69 mSv (42-118). However, younger patients (under 40 years) had a median CED of 89 mSv (55-124). This study highlights the considerable radiation exposure occurring among patients with lymphoma as a result of diagnostic imaging. To limit the risk of secondary carcinogenesis, consideration should be given to monitoring cumulative radiation exposure in individual patients as well as considering imaging modalities, which do not impart an ionizing radiation dose.

[Radiation situation prognosis for deep space: reactions of water and living systems to chronic low-dose ionizing irradiation].

PubMed

Ushakov, I B; Tsetlin, V V; Moisa, S S

2013-01-01

The authors review the findings of researches into the effects of low-dose ionizing irradiation on diverse biological objects (embryonic Japanese quails, Aspergillus niger, Spirostomum ambiguum Ehrbg., mesenchymal stem cells from mouse marrow, dry higher plants seeds, blood lymphocytes from pilots and cosmonauts). Model experiments with chronic exposure to ionizing radiation doses comparable with the measurements inside orbital vehicles and estimations for trips through the interplanetary space resulted in morphological disorders (embryonic Japanese quails, Aspergillus niger), radiation hormesis (Aspergillus niger, MSCs from mouse marrow), increase in the seed germination rate, inhibition of Spirostomum spontaneous activity, DNA damages, chromosomal aberrations, and increase of the blood lymphocytes reactivity to additional radiation loading. These facts give grounds to assume that the crucial factor in the radiation outcomes is changes in liquid medium. In other words, during extended orbiting within the magnetosphere region and interplanetary missions ionizing radiation affects primarily liquids of organism and, secondarily, its morphofunctional structures.

Stability of Molecules of Biological Importance to Ionizing Radiation: Relevance in Astrobiology

NASA Astrophysics Data System (ADS)

Meléndez-López, A. L.; Negrón-Mendoza, A.; Ramos-Bernal, S.; Colín-García, M.; Heredia, A.

2017-11-01

Our aim is to study the stability of amino acids in conditions that probably existed in the primitive environments. We study aspartic acid and glutamic acid, in solid state and aqueous solution, against high doses of gamma radiation at 298 and 77 K.

Characterizing the DNA Damage Response by Cell Tracking Algorithms and Cell Features Classification Using High-Content Time-Lapse Analysis

PubMed Central

Georgescu, Walter; Osseiran, Alma; Rojec, Maria; Liu, Yueyong; Bombrun, Maxime; Tang, Jonathan; Costes, Sylvain V.

2015-01-01

Traditionally, the kinetics of DNA repair have been estimated using immunocytochemistry by labeling proteins involved in the DNA damage response (DDR) with fluorescent markers in a fixed cell assay. However, detailed knowledge of DDR dynamics across multiple cell generations cannot be obtained using a limited number of fixed cell time-points. Here we report on the dynamics of 53BP1 radiation induced foci (RIF) across multiple cell generations using live cell imaging of non-malignant human mammary epithelial cells (MCF10A) expressing histone H2B-GFP and the DNA repair protein 53BP1-mCherry. Using automatic extraction of RIF imaging features and linear programming techniques, we were able to characterize detailed RIF kinetics for 24 hours before and 24 hours after exposure to low and high doses of ionizing radiation. High-content-analysis at the single cell level over hundreds of cells allows us to quantify precisely the dose dependence of 53BP1 protein production, RIF nuclear localization and RIF movement after exposure to X-ray. Using elastic registration techniques based on the nuclear pattern of individual cells, we could describe the motion of individual RIF precisely within the nucleus. We show that DNA repair occurs in a limited number of large domains, within which multiple small RIFs form, merge and/or resolve with random motion following normal diffusion law. Large foci formation is shown to be mainly happening through the merging of smaller RIF rather than through growth of an individual focus. We estimate repair domain sizes of 7.5 to 11 µm2 with a maximum number of ~15 domains per MCF10A cell. This work also highlights DDR which are specific to doses larger than 1 Gy such as rapid 53BP1 protein increase in the nucleus and foci diffusion rates that are significantly faster than for spontaneous foci movement. We hypothesize that RIF merging reflects a "stressed" DNA repair process that has been taken outside physiological conditions when too many DSB occur at once. High doses of ionizing radiation lead to RIF merging into repair domains which in turn increases DSB proximity and misrepair. Such finding may therefore be critical to explain the supralinear dose dependence for chromosomal rearrangement and cell death measured after exposure to ionizing radiation. PMID:26107175

Characterizing the DNA damage response by cell tracking algorithms and cell features classification using high-content time-lapse analysis

DOE PAGES

Georgescu, Walter; Osseiran, Alma; Rojec, Maria; ...

2015-06-24

Traditionally, the kinetics of DNA repair have been estimated using immunocytochemistry by labeling proteins involved in the DNA damage response (DDR) with fluorescent markers in a fixed cell assay. However, detailed knowledge of DDR dynamics across multiple cell generations cannot be obtained using a limited number of fixed cell time-points. Here we report on the dynamics of 53BP1 radiation induced foci (RIF) across multiple cell generations using live cell imaging of non-malignant human mammary epithelial cells (MCF10A) expressing histone H2B-GFP and the DNA repair protein 53BP1-mCherry. Using automatic extraction of RIF imaging features and linear programming techniques, we were ablemore » to characterize detailed RIF kinetics for 24 hours before and 24 hours after exposure to low and high doses of ionizing radiation. High-content-analysis at the single cell level over hundreds of cells allows us to quantify precisely the dose dependence of 53BP1 protein production, RIF nuclear localization and RIF movement after exposure to X-ray. Using elastic registration techniques based on the nuclear pattern of individual cells, we could describe the motion of individual RIF precisely within the nucleus. We show that DNA repair occurs in a limited number of large domains, within which multiple small RIFs form, merge and/or resolve with random motion following normal diffusion law. Large foci formation is shown to be mainly happening through the merging of smaller RIF rather than through growth of an individual focus. We estimate repair domain sizes of 7.5 to 11 µm 2 with a maximum number of ~15 domains per MCF10A cell. This work also highlights DDR which are specific to doses larger than 1 Gy such as rapid 53BP1 protein increase in the nucleus and foci diffusion rates that are significantly faster than for spontaneous foci movement. We hypothesize that RIF merging reflects a "stressed" DNA repair process that has been taken outside physiological conditions when too many DSB occur at once. High doses of ionizing radiation lead to RIF merging into repair domains which in turn increases DSB proximity and misrepair. Furthermore, such finding may therefore be critical to explain the supralinear dose dependence for chromosomal rearrangement and cell death measured after exposure to ionizing radiation.« less

Compendium of Single Event Effects, Total Ionizing Dose, and Displacement Damage for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

LaBel, Kenneth A.; OBryan, Martha V.; Chen, Dakai; Campola, Michael J.; Casey, Megan C.; Pellish, Jonathan A.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Ladbury, Raymond L.;

Design and characterization of a new high-dose-rate brachytherapy Valencia applicator for larger skin lesions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candela-Juan, C., E-mail: ccanjuan@gmail.com; Niatsetski, Y.; Laarse, R. van der

Purpose: The aims of this study were (i) to design a new high-dose-rate (HDR) brachytherapy applicator for treating surface lesions with planning target volumes larger than 3 cm in diameter and up to 5 cm in size, using the microSelectron-HDR or Flexitron afterloader (Elekta Brachytherapy) with a {sup 192}Ir source; (ii) to calculate by means of the Monte Carlo (MC) method the dose distribution for the new applicator when it is placed against a water phantom; and (iii) to validate experimentally the dose distributions in water. Methods: The PENELOPE2008 MC code was used to optimize dwell positions and dwell times.more » Next, the dose distribution in a water phantom and the leakage dose distribution around the applicator were calculated. Finally, MC data were validated experimentally for a {sup 192}Ir mHDR-v2 source by measuring (i) dose distributions with radiochromic EBT3 films (ISP); (ii) percentage depth–dose (PDD) curve with the parallel-plate ionization chamber Advanced Markus (PTW); and (iii) absolute dose rate with EBT3 films and the PinPoint T31016 (PTW) ionization chamber. Results: The new applicator is made of tungsten alloy (Densimet) and consists of a set of interchangeable collimators. Three catheters are used to allocate the source at prefixed dwell positions with preset weights to produce a homogenous dose distribution at the typical prescription depth of 3 mm in water. The same plan is used for all available collimators. PDD, absolute dose rate per unit of air kerma strength, and off-axis profiles in a cylindrical water phantom are reported. These data can be used for treatment planning. Leakage around the applicator was also scored. The dose distributions, PDD, and absolute dose rate calculated agree within experimental uncertainties with the doses measured: differences of MC data with chamber measurements are up to 0.8% and with radiochromic films are up to 3.5%. Conclusions: The new applicator and the dosimetric data provided here will be a valuable tool in clinical practice, making treatment of large skin lesions simpler, faster, and safer. Also the dose to surrounding healthy tissues is minimal.« less

SU-C-201-03: Ionization Chamber Collection Efficiency in Pulsed Radiation Fields of High Pulse Dose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gotz, M; Karsch, L; Pawelke, J

Purpose: To investigate the reduction of collection efficiency of ionization chambers (IC) by volume recombination and its correction in pulsed fields of very high pulse dose. Methods: Measurements of the collection efficiency of a plane-parallel advanced Markus IC (PTW 34045, 1mm electrode spacing, 300V nominal voltage) were obtained for collection voltages of 100V and 300V by irradiation with a pulsed electron beam (20MeV) of varied pulse dose up to approximately 600mGy (0.8nC liberated charge). A reference measurement was performed with a Faraday cup behind the chamber. It was calibrated for the liberated charge in the IC by a linear fitmore » of IC measurement to reference measurement at low pulse doses. The results were compared to the commonly used two voltage approximation (TVA) and to established theories for volume recombination, with and without considering a fraction of free electrons. In addition, an equation system describing the charge transport and reactions in the chamber was solved numerically. Results: At 100V collection voltage and moderate pulse doses the established theories accurately predict the observed collection efficiency, but at extreme pulse doses a fraction of free electrons needs to be considered. At 300V the observed collection efficiency deviates distinctly from that predicted by any of the established theories, even at low pulse doses. However, the numeric solution of the equation system is able to reproduce the measured collection efficiency across the entire dose range of both voltages with a single set of parameters. Conclusion: At high electric fields (3000V/cm here) the existing theoretical descriptions of collection efficiency, including the TVA, are inadequate to predict pulse dose dependency. Even at low pulse doses they might underestimate collection efficiency. The presented, more accurate numeric solution, which considers additional effects like electric shielding by the charges, might provide a valuable tool for future investigations. This project was funded by the German ministry of research and education (BMBF) under grant number: 03Z1N511 and by the state of Saxony under grant number: B 209.« less

NOTE: Calibration of low-energy electron beams from a mobile linear accelerator with plane-parallel chambers using both TG-51 and TG-21 protocols

NASA Astrophysics Data System (ADS)

Beddar, A. S.; Tailor, R. C.

2004-04-01

A new approach to intraoperative radiation therapy led to the development of mobile linear electron accelerators that provide lower electron energy beams than the usual conventional accelerators commonly encountered in radiotherapy. Such mobile electron accelerators produce electron beams that have nominal energies of 4, 6, 9 and 12 MeV. This work compares the absorbed dose output calibrations using both the AAPM TG-51 and TG-21 dose calibration protocols for two types of ion chambers: a plane-parallel (PP) ionization chamber and a cylindrical ionization chamber. Our results indicate that the use of a 'Markus' PP chamber causes 2 3% overestimation in dose output determination if accredited dosimetry-calibration laboratory based chamber factors \\big(N_{{\\rm D},{\\rm w}}^{{}^{60}{\\rm Co}}, N_x\\big) are used. However, if the ionization chamber factors are derived using a cross-comparison at a high-energy electron beam, then a good agreement is obtained (within 1%) with a calibrated cylindrical chamber over the entire energy range down to 4 MeV. Furthermore, even though the TG-51 does not recommend using cylindrical chambers at the low energies, our results show that the cylindrical chamber has a good agreement with the PP chamber not only at 6 MeV but also down to 4 MeV electron beams.

THE EFFECT OF IONIZING RADIATIONS ON ONTOGENESIS IN BIRDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinu, M.

1963-01-01

The effect of strong doses of ionizing radiations on the ontogenetic development of birds and formation of mutations was studied. The data obtained show that ionizing radiations have a different effect on the biological substratum, depending on their nature and relationship to physiological limits. Gamma radiations have a negative action on the biochemical process altering ths substratum and upsetting the entity of heredity. It was found that x rays produce a temporary stimulating effect on metabolic processes influencing the vitality, ontogenetic development, resistance, the appearance of sexual instinct, and the fertility. Ionizing radiations affect functioning of endocrinic glands and consequentlymore » the ratio of sexes in the offspring. From the results obtained it cand be stated that strong doses of ionizing radiations may be used to obtain variation of mutations, and that in general they are a factor in the evolution of the living organism. (OTS)« less

Effects of ionizing radiations on a pharmaceutical compound, chloramphenicol

NASA Astrophysics Data System (ADS)

Varshney, L.; Patel, K. M.

1994-05-01

Chloramphenicol, a broad spectrum antibiotic, has been irradiated using Cobalt-60 γ radiation and electron beam at graded radiation doses upto 100 kGy. Several degradation products and free radicals are formed on irradiation. Purity, degradation products, free radicals, discolouration, crystallinity, solubility and entropy of radiation processing have been investigated. Aqueous solutions undergo extensive radiolysis even at low doses. Physico-chemical, microbiological and toxicological tests do not show significant degradation at sterilization dose. High performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), UV-spectrophotometry, diffuse reflectance spectroscopy (DRS) and electron spin resonance spectroscopy (ESR) techniques were employed for the investigations.

Acute radiation syndrome: assessment and management.

PubMed

Donnelly, Elizabeth H; Nemhauser, Jeffrey B; Smith, James M; Kazzi, Ziad N; Farfán, Eduardo B; Chang, Arthur S; Naeem, Syed F

2010-06-01

Primary care physicians may be unprepared to diagnose and treat rare, yet potentially fatal, illnesses such as acute radiation syndrome (ARS). ARS, also known as radiation sickness, is caused by exposure to a high dose of penetrating, ionizing radiation over a short period of time. The time to onset of ARS is dependent on the dose received, but even at the lowest doses capable of causing illness, this will occur within a matter of hours to days. This article describes the clinical manifestations of ARS, provides guidelines for assessing its severity, and makes recommendations for managing ARS victims.

The effects of low doses of ionizing radiation - A question of ethics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tschaeche, A.N.

1996-12-31

Three ethical questions are asked and answered about the current state of affairs concerning how those in power manipulate public understanding of the effects of low doses of ionizing radiation. The questions are as follows: (1) Is it ethical to frighten people when you do not know that there is anything to be frightened of? (2) Is it ethical to be so conservative that resources are spent to solve a problem that may not exist? (3) Is it ethical not to tell the whole truth about the effects of low levels of ionizing radiation?

Is ionizing radiation regulated more stringently than chemical carcinogens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Travis, C.C.; Pack, S.R.; Hattemer-Frey, H.A.

1989-04-01

It is widely believed that United States government agencies regulate exposure to ionizing radiation more stringently than exposure to chemical carcinogens. It is difficult to verify this perception, however, because chemical carcinogens and ionizing radiation are regulated using vastly different strategies. Chemical carcinogens are generally regulated individually. Regulators consider the risk of exposure to one chemical rather than the cumulative radiation exposure from all sources. Moreover, standards for chemical carcinogens are generally set in terms of quantities released or resultant environmental concentrations, while standards for ionizing radiation are set in terms of dose to the human body. Since chemicals andmore » ionizing radiation cannot be compared on the basis of equal dose to the exposed individual, standards regulating chemicals and ionizing radiation cannot be compared directly. It is feasible, however, to compare the two sets of standards on the basis of equal risk to the exposed individual, assuming that standards for chemicals and ionizing radiation are equivalent if estimated risk levels are equitable. This paper compares risk levels associated with current standards for ionizing radiation and chemical carcinogens. The authors do not attempt to determine whether either type of risk is regulated too stringently or not stringently enough but endeavor only to ascertain if ionizing radiation is actually regulated more strictly than chemical carcinogens.« less

MAGIC with formaldehyde applied to dosimetry of HDR brachytherapy source

NASA Astrophysics Data System (ADS)

Marques; T; Fernandes; J; Barbi; G; Nicolucci; P; Baffa; O

2009-05-01

The use of polymer gel dosimeters in brachytherapy can allow the determination of three-dimensional dose distributions in large volumes and with high spatial resolution if an adequate calibration process is performed. One of the major issues in these experiments is the polymer gel response dependence on dose rate when high dose rate sources are used and the doses in the vicinity of the sources are to be determinated. In this study, the response of a modified MAGIC polymer gel with formaldehyde around an Iridium-192 HDR brachytherapy source is presented. Experimental results obtained with this polymer gel were compared with ionization chamber measurements and with Monte Carlo simulation with PENELOPE. A maximum difference of 3.10% was found between gel dose measurements and Monte Carlo simulation at a radial distance of 18 mm from the source. The results obtained show that the gel's response is strongly influenced by dose rate and that a different calibration should be used for the vicinity of the source and for regions of lower dose rates. The results obtained in this study show that, provided the proper calibration is performed, MAGIC with formaldehyde can be successfully used to accurate determinate dose distributions form high dose rate brachytherapy sources.

Residential Exposure to Natural Background Radiation and Risk of Childhood Acute Leukemia in France, 1990-2009.

PubMed

Demoury, Claire; Marquant, Fabienne; Ielsch, Géraldine; Goujon, Stéphanie; Debayle, Christophe; Faure, Laure; Coste, Astrid; Laurent, Olivier; Guillevic, Jérôme; Laurier, Dominique; Hémon, Denis; Clavel, Jacqueline

2017-04-01

Exposures to high-dose ionizing radiation and high-dose rate ionizing radiation are established risk factors for childhood acute leukemia (AL). The risk of AL following exposure to lower doses due to natural background radiation (NBR) has yet to be conclusively determined. AL cases diagnosed over 1990-2009 (9,056 cases) were identified and their municipality of residence at diagnosis collected by the National Registry of Childhood Cancers. The Geocap study, which included the 2,763 cases in 2002-2007 and 30,000 population controls, was used for complementary analyses. NBR exposures were modeled on a fine scale (36,326 municipalities) based on measurement campaigns and geological data. The power to detect an association between AL and dose to the red bone marrow (RBM) fitting UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) predictions was 92%, 45% and 99% for exposure to natural gamma radiation, radon and total radiation, respectively. AL risk, irrespective of subtype and age group, was not associated with the exposure of municipalities to radon or gamma radiation in terms of yearly exposure at age reached, cumulative exposure or RBM dose. There was no confounding effect of census-based socio-demographic indicators, or environmental factors (road traffic, high voltage power lines, vicinity of nuclear plants) related to AL in the Geocap study. Our findings do not support the hypothesis that residential exposure to NBR increases the risk of AL, despite the large size of the study, fine scale exposure estimates and wide range of exposures over France. However, our results at the time of diagnosis do not rule out a slight association with gamma radiation at the time of birth, which would be more in line with the recent findings in the UK and Switzerland.

Investigation Into Radiation-Induced Compaction of Zerodur (trademark)

NASA Technical Reports Server (NTRS)

Edwards, D. L.; Herren, K.; Hayden, M.; McDonald, K.; Sims, J. A.; Semmel, C. L.

1996-01-01

Zerodur is a low coefficient of thermal expansion glass-ceramic material. This property makes Zerodur an excellent material for high precision optical substrates. Functioning as a high precision optical substrate, a material must be dimensionally stable in the system operating environment. Published data indicate that Zerodur is dimensionally unstable when exposed to large doses of ionizing radiation. The dimensional instability is discussed as an increase in Zerodur density. This increase in density is described as a compaction. Experimental data showing proton-induced compaction of Zerodur is presented. The dependence of compaction on proton dose was determined to be a power law relationship.

Investigation Into Radiation-Induced Compaction of Zerodur (trademark)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, D.L.; Herren, K.; Hayden, M.

1996-03-01

Zerodur is a low coefficient of thermal expansion glass-ceramic material. This property makes Zerodur an excellent material for high precision optical substrates. Functioning as a high precision optical substrate, a material must be dimensionally stable in the system operating environment. Published data indicate that Zerodur is dimensionally unstable when exposed to large doses of ionizing radiation. The dimensional instability is discussed as an increase in Zerodur density. This increase in density is described as a compaction. Experimental data showing proton-induced compaction of Zerodur is presented. The dependence of compaction on proton dose was determined to be a power law relationship.

Low dose ionizing radiation detection using conjugated polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, E.A.B.; Borin, J.F.; Nicolucci, P.

2005-03-28

In this work, the effect of gamma radiation on the optical properties of poly[2-methoxy-5-(2{sup '}-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) is studied. The samples were irradiated at room temperature with different doses from 0 Gy to 152 Gy using a {sup 60}Co gamma ray source. For thin films, significant changes in the UV-visible spectra were only observed at high doses (>1 kGy). In solution, shifts in absorption peaks are observed at low doses (<10 Gy), linearly dependent on dose. The shifts are explained by conjugation reduction, and possible causes are discussed. Our results indicate that MEH-PPV solution can be used as a dosimeter adequatemore » for medical applications.« less

Effect of gamma and e-beam radiation on the essential oils of Thymus vulgaris thymoliferum, Eucalyptus radiata, and Lavandula angustifolia.

PubMed

Haddad, Mohamed; Herent, Marie-France; Tilquin, Bernard; Quetin-Leclercq, Joëlle

2007-07-25

The microbiological contamination of raw plant materials is common and may be adequately reduced by radiation processing. This study evaluated the effects of gamma- and e-beam ionizing radiations (25 kGy) on three plants used as food or as medicinal products (Thymus vulgaris L., Eucalyptus radiata D.C., and Lavandula angustifolia Mill.) as well as their effects on extracted or commercial essential oils and pure standard samples. Comparison between irradiated and nonirradiated samples was performed by GC/FID and GC/MS. At the studied doses, gamma and e-beam ionizing radiation did not induce any detectable qualitative or quantitative significant changes in the contents and yields of essential oils immediately after ionizing radiation of plants or commercial essential oils and standards. As the maximum dose tested (25 kGy) is a sterilizing dose (much higher than doses used for decontamination of vegetable drugs), it is likely that even decontamination with lower doses will not modify yields or composition of essential oils of these three plants.

Design and Calibration of a X-Ray Millibeam

DTIC Science & Technology

2005-12-01

developed for use in Fricke dosimetry , parallel-plate ionization chambers, Lithium Fluoride thermoluminescent dosimetry ( TLD ), and EBT GafChromic...thermoluminescent dosimetry ( TLD ), and EBT GafChromic film to characterize the spatial distribution and accuracy of the doses produced by the Faxitron. A...absorbed dose calibration factors for use in Fricke dosimetry , parallel-plate ionization chambers, Lithium Fluoride (LiF) TLD , and EBT GafChromic film. The

Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams.

PubMed

Mandapaka, A K; Ghebremedhin, A; Patyal, B; Marinelli, Marco; Prestopino, G; Verona, C; Verona-Rinati, G

2013-12-01

To investigate the dosimetric properties of a synthetic single crystal diamond Schottky diode for accurate relative dose measurements in large and small field high-energy clinical proton beams. The dosimetric properties of a synthetic single crystal diamond detector were assessed by comparison with a reference Markus parallel plate ionization chamber, an Exradin A16 microionization chamber, and Exradin T1a ion chamber. The diamond detector was operated at zero bias voltage at all times. Comparative dose distribution measurements were performed by means of Fractional depth dose curves and lateral beam profiles in clinical proton beams of energies 155 and 250 MeV for a 14 cm square cerrobend aperture and 126 MeV for 3, 2, and 1 cm diameter circular brass collimators. ICRU Report No. 78 recommended beam parameters were used to compare fractional depth dose curves and beam profiles obtained using the diamond detector and the reference ionization chamber. Warm-up∕stability of the detector response and linearity with dose were evaluated in a 250 MeV proton beam and dose rate dependence was evaluated in a 126 MeV proton beam. Stem effect and the azimuthal angle dependence of the diode response were also evaluated. A maximum deviation in diamond detector signal from the average reading of less than 0.5% was found during the warm-up irradiation procedure. The detector response showed a good linear behavior as a function of dose with observed deviations below 0.5% over a dose range from 50 to 500 cGy. The detector response was dose rate independent, with deviations below 0.5% in the investigated dose rates ranging from 85 to 300 cGy∕min. Stem effect and azimuthal angle dependence of the diode signal were within 0.5%. Fractional depth dose curves and lateral beam profiles obtained with the diamond detector were in good agreement with those measured using reference dosimeters. The observed dosimetric properties of the synthetic single crystal diamond detector indicate that its behavior is proton energy independent and dose rate independent in the investigated energy and dose rate range and it is suitable for accurate relative dosimetric measurements in large as well as in small field high energy clinical proton beams.

Leukemia risk associated with chronic external exposure to ionizing radiation in a French cohort of nuclear workers.

PubMed

Metz-Flamant, C; Samson, E; Caër-Lorho, S; Acker, A; Laurier, D

2012-11-01

Leukemia is one of the earliest cancer effects observed after acute exposure to relatively high doses of ionizing radiation. Leukemia mortality after external exposure at low doses and low-dose rates has been investigated at the French Atomic Energy Commission (CEA) and Nuclear Fuel Company (AREVA NC) after an additional follow-up of 10 years. The cohort included radiation-monitored workers employed for at least one year during 1950-1994 at CEA or AREVA NC and followed during 1968-2004. Association between external exposure and leukemia mortality was estimated with excess relative risk (ERR) models and time-dependent modifying factors were investigated with time windows. The cohort included 36,769 workers, followed for an average of 28 years, among whom 73 leukemia deaths occurred. Among the workers with a positive recorded dose, the mean cumulative external dose was 21.7 mSv. Results under a 2-year lag assumption suggested that the risk of leukemia (except chronic lymphatic leukemia) increased significantly by 8% per 10 mSv. The magnitude of the association for myeloid leukemia was larger. The higher ERR/Sv for doses received 2-14 years earlier suggest that time since exposure modifies the effect. The ERR/Sv also appeared higher for doses received at exposure rates ≥20 mSv per year. These results are consistent with those found in other studies of nuclear workers. However, confidence intervals are still wide. Further analyses should be conducted in pooled cohorts of nuclear workers.

Eye Lens Opacities Among Physicians Occupationally Exposed to Ionizing Radiation.

PubMed

Auvinen, Anssi; Kivelä, Tero; Heinävaara, Sirpa; Mrena, Samy

2015-08-01

We compared the frequency of lens opacities among physicians with and without occupational exposure to ionizing radiation, and estimated dose-response between cumulative dose and opacities. We conducted ophthalmologic examinations of 21 physicians with occupational exposure to radiation and 16 unexposed physicians. Information on cumulative radiation doses (mean 111 mSv) was based on dosimeter readings recorded in a national database on occupational exposures. Lens changes were evaluated using the Lens Opacities Classification System II, with an emphasis on posterior subcapsular (PSC) and cortical changes. Among the exposed physicians, the prevalences of cortical and PSC changes were both 11% (3/21), and the corresponding frequencies in the unexposed group were 44% (n = 7) and 6% (n = 1). For dose-response analysis, the data were pooled with 29 exposed physicians from our previous study. No association of either type of lens changes with cumulative recorded dose was observed. Our findings do not indicate an increased frequency of lens opacities in physicians with occupational exposure to ionizing radiation. However, the subjects in this study have received relatively low doses and therefore the results do not exclude small increases in lens opacities or contradict the studies reporting increases among interventional cardiologists with materially higher cumulative doses. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Degradation of fluoroquinolone antibiotics during ionizing radiation treatment and assessment of antibacterial activity, toxicity and biodegradability of the products

NASA Astrophysics Data System (ADS)

Tegze, Anna; Sági, Gyuri; Kovács, Krisztina; Homlok, Renáta; Tóth, Tünde; Mohácsi-Farkas, Csilla; Wojnárovits, László; Takács, Erzsébet

2018-06-01

This work aimed at investigating the ionizing radiation induced degradation of two fluoroquinolone antibiotics: norfloxacin and ciprofloxacin. At 0.1 mmol dm-3 concentration a low dose, 2 kGy was sufficient to degrade the initial molecules. However, despite of the high removal efficiency the degrees of both the mineralization and the oxidation were low, ∼10% and ∼25%, respectively. (The difference between the results obtained in norfloxacin and ciprofloxacin solutions was not statistically significant.) Broth microdilution tests carried out on Staphylococcus aureus evidenced removal of antibacterial activity in samples irradiated with 2 kGy. Acute toxicity determined on Vibrio fischeri bacteria showed increased toxicity at low doses indicating that the early degradation products were more toxic than the initial molecules. The results of biodegradation experiments performed in activated sludge have shown that the degradation products have become available to the metabolic processes of the microorganisms.

Study the Characterization of Spectral Absorbance on Irradiated Milk Protein

NASA Astrophysics Data System (ADS)

Fohely, F.; Suardi, N.

2018-04-01

The milk has been adopted as a structural nature food for a long era since it is containing most of the growth factors, protective agents, and enzymes needed for the body. a few attempts have been conducted to treat the dairy products especially raw milk by the means of ionizing radiation. as its production has been an expanding industry for many years due to the high demands from the consumers worldwide, there is still some doubt about preserving these products by irradiation. In this work, a preliminary effort to describe the influences of ionizing radiation on raw milk’s protein will be devoted to measuring the spectral absorbance of the total protein (after subjected to varied radiation doses) by UV-VIS-NIR spectroscopy analysis. The absorbance spectrum then analyzed based on absorbance spectra of organic compounds. A comparison is made between the effects of different radiation doses to estimate the influence in milk’s structure.

MO-FG-CAMPUS-IeP1-05: New Ionization Chamber Dosimetry of Absorbed Dose to Water in Diagnostic KV X-Ray Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Araki, F; Ohno, T

Purpose: To develop new ionization chamber dosimetry of absorbed dose to water in diagnostic kV x-ray beams, by using a beam quality conversion factor, kQ, for Co-60 to kV x-ray and an ionization conversion factor for a water-substitute plastic phantom. Methods: kQ was calculated for aluminum half value-layers (Al-HVLs) of 1.5 mm to 8 mm which were generated by kV x-ray beams of 50 to 120 kVp. Twenty-two energy spectra for ten effective energies (Eeff) were calculated by a SpecCalc program. Depth doses in water were calculated at 5 × 5 to 30 × 30 cm{sup 2} fields. Output factorsmore » were also obtained from the dose ratio for a 10 × 10 cm{sup 2} field. kQ was obtained for a PTW30013 Former ion chamber. In addition, an ionization conversion factor of the PWDT phantom to water was calculated. All calculations were performed with EGSnrc/cavity code and egs-chamber codes. Results: The x-ray beam energies for 1.5 mm to 8 mm Al-HVLs ranged in Eeff of 25.7 to 54.3 keV. kQ for 1.5 mm to 8 mm Al-HVLs were 0.831 to 0.897, at 1 and 2 cm depths for a 10 × 10 cm2 field. Similarly, output factors for 5 × 5 to 30 × 30 cm{sup 2} fields were 0.937 to 1.033 for 25.7 keV and 0.857 to 1.168 for 54.3 keV. The depth dose in a PWDT phantom decreased up to 5% compared to that in water at depth of ten percent of maximum dose for 1.5 mm Al-HVL. The ionization ratios of water/PWDT phantoms for the PTW30013 chamber were 1.012 to 1.007 for 1.5 mm to 8 mm Al-HVLs at 1 cm depth. Conclusion: It became possible to directly measure the absorbed dose to water with the ionization chamber in diagnostic kV x-ray beams, by using kQ and the PWDT phantom.« less

Role of Ionizing Radiation in Neurodegenerative Diseases

PubMed Central

Sharma, Neel K.; Sharma, Rupali; Mathur, Deepali; Sharad, Shashwat; Minhas, Gillipsie; Bhatia, Kulsajan; Anand, Akshay; Ghosh, Sanchita P.

2018-01-01

Ionizing radiation (IR) from terrestrial sources is continually an unprotected peril to human beings. However, the medical radiation and global radiation background are main contributors to human exposure and causes of radiation sickness. At high-dose exposures acute radiation sickness occurs, whereas chronic effects may persist for a number of years. Radiation can increase many circulatory, age related and neurodegenerative diseases. Neurodegenerative diseases occur a long time after exposure to radiation, as demonstrated in atomic bomb survivors, and are still controversial. This review discuss the role of IR in neurodegenerative diseases and proposes an association between neurodegenerative diseases and exposure to IR. PMID:29867445

Study of proton radiation effects among diamond and rectangular gate MOSFET layouts

NASA Astrophysics Data System (ADS)

Seixas, L. E., Jr.; Finco, S.; Silveira, M. A. G.; Medina, N. H.; Gimenez, S. P.

2017-01-01

This paper describes an experimental comparative study of proton ionizing radiation effects between the metal-oxide-semiconductor (MOS) Field Effect Transistors (MOSFETs) implemented with hexagonal gate shapes (diamond) and their respective counterparts designed with the classical rectangular ones, regarding the same gate areas, channel widths and geometrical ratios (W/L). The devices were manufactured by using the 350 nm bulk complementary MOS (CMOS) integrated circuits technology. The diamond MOSFET with α angles higher or equal to 90° tends to present a smaller vulnerability to the high doses ionizing radiation than those observed in the typical rectangular MOSFET counterparts.

The increase in animal mortality risk following exposure to sparsely ionizing radiation is not linear quadratic with dose

DOE PAGES

Haley, Benjamin M.; Paunesku, Tatjana; Grdina, David J.; ...

2015-12-09

The US government regulates allowable radiation exposures relying, in large part, on the seventh report from the committee to estimate the Biological Effect of Ionizing Radiation (BEIR VII), which estimated that most contemporary exposures- protracted or low-dose, carry 1.5 fold less risk of carcinogenesis and mortality per Gy than acute exposures of atomic bomb survivors. This correction is known as the dose and dose rate effectiveness factor for the life span study of atomic bomb survivors (DDREF LSS). As a result, it was calculated by applying a linear-quadratic dose response model to data from Japanese atomic bomb survivors and amore » limited number of animal studies.« less

The increase in animal mortality risk following exposure to sparsely ionizing radiation is not linear quadratic with dose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haley, Benjamin M.; Paunesku, Tatjana; Grdina, David J.

The US government regulates allowable radiation exposures relying, in large part, on the seventh report from the committee to estimate the Biological Effect of Ionizing Radiation (BEIR VII), which estimated that most contemporary exposures- protracted or low-dose, carry 1.5 fold less risk of carcinogenesis and mortality per Gy than acute exposures of atomic bomb survivors. This correction is known as the dose and dose rate effectiveness factor for the life span study of atomic bomb survivors (DDREF LSS). As a result, it was calculated by applying a linear-quadratic dose response model to data from Japanese atomic bomb survivors and amore » limited number of animal studies.« less

Triple ionization chamber method for clinical dose monitoring with a Be-covered Li BNCT field.

PubMed

Nguyen, Thanh Tat; Kajimoto, Tsuyoshi; Tanaka, Kenichi; Nguyen, Chien Cong; Endo, Satoru

2016-11-01

Fast neutron, gamma-ray, and boron doses have different relative biological effectiveness (RBE). In boron neutron capture therapy (BNCT), the clinical dose is the total of these dose components multiplied by their RBE. Clinical dose monitoring is necessary for quality assurance of the irradiation profile; therefore, the fast neutron, gamma-ray, and boron doses should be separately monitored. To estimate these doses separately, and to monitor the boron dose without monitoring the thermal neutron fluence, the authors propose a triple ionization chamber method using graphite-walled carbon dioxide gas (C-CO 2 ), tissue-equivalent plastic-walled tissue-equivalent gas (TE-TE), and boron-loaded tissue-equivalent plastic-walled tissue-equivalent gas [TE(B)-TE] chambers. To use this method for dose monitoring for a neutron and gamma-ray field moderated by D 2 O from a Be-covered Li target (Be-covered Li BNCT field), the relative sensitivities of these ionization chambers are required. The relative sensitivities of the TE-TE, C-CO 2 , and TE(B)-TE chambers to fast neutron, gamma-ray, and boron doses are calculated with the particle and heavy-ion transport code system (PHITS). The relative sensitivity of the TE(B)-TE chamber is calculated with the same method as for the TE-TE and C-CO 2 chambers in the paired chamber method. In the Be-covered Li BNCT field, the relative sensitivities of the ionization chambers to fast neutron, gamma-ray, and boron doses are calculated from the kerma ratios, mass attenuation coefficient tissue-to-wall ratios, and W-values. The Be-covered Li BNCT field consists of neutrons and gamma-rays which are emitted from a Be-covered Li target, and this resultant field is simulated by using PHITS with the cross section library of ENDF-VII. The kerma ratios and mass attenuation coefficient tissue-to-wall ratios are determined from the energy spectra of neutrons and gamma-rays in the Be-covered Li BNCT field. The W-value is calculated from recoil charged particle spectra by the collision of neutrons and gamma-rays with the wall and gas materials of the ionization chambers in the gas cavities of TE-TE, C-CO 2 , and TE(B)-TE chambers ( 10 B concentrations of 10, 50, and 100 ppm in the TE-wall). The calculated relative sensitivity of the C-CO 2 chamber to the fast neutron dose in the Be-covered Li BNCT field is 0.029, and those of the TE-TE and TE(B)-TE chambers are both equal to 0.965. The relative sensitivities of the C-CO 2 , TE-TE, and TE(B)-TE chambers to the gamma-ray dose in the Be-covered Li BNCT field are all 1 within the 1% calculation uncertainty. The relative sensitivities of TE(B)-TE to boron dose with concentrations of 10, 50, and 100 ppm 10 B are calculated to be 0.865 times the ratio of the in-tumor to in-chamber wall boron concentration. The fast neutron, gamma-ray, and boron doses of a tumor in-air can be separately monitored by the triple ionization chamber method in the Be-covered Li BNCT field. The results show that these doses can be easily converted to the clinical dose with the depth correction factor in the body and the RBE.

Biodosimetry of ionizing radiation by selective painting of prematurely condensed chromosomes in human lymphocytes

NASA Technical Reports Server (NTRS)

Durante, M.; George, K.; Yang, T. C.

1997-01-01

Painting of interphase chromosomes can be useful for biodosimetric purposes in particular cases such as radiation therapy, accidental exposure to very high radiation doses and exposure to densely ionizing radiation, for example during space missions. Biodosimetry of charged-particle radiation is analyzed in the present paper. Target cells were human peripheral blood lymphocytes irradiated in vitro with gamma rays, protons and iron ions. After exposure, lymphocytes were incubated for different times to allow repair of radiation-induced damage and then fused to mitotic hamster cells to promote premature condensation in the interphase chromosomes. Chromosome spreads were then hybridized with whole-chromosome DNA probes labeled with fluorescent stains. Dose-response curves for the induction of chromatin fragments shortly after exposure, as well as the kinetics of rejoining and misrejoining, were not markedly dependent on linear energy transfer. However, after exposure to heavy ions, more aberrations were scored in the interphase cells after incubation for repair than in metaphase samples harvested at the first postirradiation mitosis. On the other hand, no significant differences were observed in the two samples after exposure to sparsely ionizing radiation. These results suggest that interphase chromosome painting can be a useful tool for biodosimetry of particle radiation.

Biodosimetry of ionizing radiation by selective painting of prematurely condensed chromosomes in human lymphocytes.

PubMed

Durante, M; George, K; Yang, T C

1997-11-01

Painting of interphase chromosomes can be useful for biodosimetric purposes in particular cases such as radiation therapy, accidental exposure to very high radiation doses and exposure to densely ionizing radiation, for example during space missions. Biodosimetry of charged-particle radiation is analyzed in the present paper. Target cells were human peripheral blood lymphocytes irradiated in vitro with gamma rays, protons and iron ions. After exposure, lymphocytes were incubated for different times to allow repair of radiation-induced damage and then fused to mitotic hamster cells to promote premature condensation in the interphase chromosomes. Chromosome spreads were then hybridized with whole-chromosome DNA probes labeled with fluorescent stains. Dose-response curves for the induction of chromatin fragments shortly after exposure, as well as the kinetics of rejoining and misrejoining, were not markedly dependent on linear energy transfer. However, after exposure to heavy ions, more aberrations were scored in the interphase cells after incubation for repair than in metaphase samples harvested at the first postirradiation mitosis. On the other hand, no significant differences were observed in the two samples after exposure to sparsely ionizing radiation. These results suggest that interphase chromosome painting can be a useful tool for biodosimetry of particle radiation.

Feasibility of using two‐dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry

PubMed Central

Li, Jonathan; Samant, Sanjiv

2011-01-01

Two‐dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from ‐0.2%~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry. PACS number: 87.55.N‐

Non-targeted effects of ionizing radiation–implications for low dose risk

PubMed Central

Kadhim, Munira; Salomaa, Sisko; Wright, Eric; Hildebrandt, Guido; Belyakov, Oleg V.; Prise, Kevin M.; Little, Mark P.

2014-01-01

Non-DNA targeted effects of ionizing radiation, which include genomic instability, and a variety of bystander effects including abscopal effects and bystander mediated adaptive response, have raised concerns about the magnitude of low-dose radiation risk. Genomic instability, bystander effects and adaptive responses are powered by fundamental, but not clearly understood systems that maintain tissue homeostasis. Despite excellent research in this field by various groups, there are still gaps in our understanding of the likely mechanisms associated with non-DNA targeted effects, particularly with respect to systemic (human health) consequences at low and intermediate doses of ionizing radiation. Other outstanding questions include links between the different non-targeted responses and the variations in response observed between individuals and cell lines, possibly a function of genetic background. Furthermore, it is still not known what the initial target and early interactions in cells are that give rise to non-targeted responses in neighbouring or descendant cells. This paper provides a commentary on the current state of the field as a result of the Non-targeted effects of ionizing radiation (NOTE) Integrated Project funded by the European Union. Here we critically examine the evidence for non-targeted effects, discuss apparently contradictory results and consider implications for low-dose radiation health effects. PMID:23262375

Ionizing radiation-induced mutagenesis: radiation studies in Neurospora predictive for results in mammalian cells

NASA Technical Reports Server (NTRS)

Evans, H. H.; DeMarini, D. M.

1999-01-01

Ionizing radiation was the first mutagen discovered and was used to develop the first mutagenicity assay. In the ensuing 70+ years, ionizing radiation became a fundamental tool in understanding mutagenesis and is still a subject of intensive research. Frederick de Serres et al. developed and used the Neurospora crassa ad-3 system initially to explore the mutagenic effects of ionizing radiation. Using this system, de Serres et al. demonstrated the dependence of the frequency and spectra of mutations induced by ionizing radiation on the dose, dose rate, radiation quality, repair capabilities of the cells, and the target gene employed. This work in Neurospora predicted the subsequent observations of the mutagenic effects of ionizing radiation in mammalian cells. Modeled originally on the mouse specific-locus system developed by William L. Russell, the N. crassa ad-3 system developed by de Serres has itself served as a model for interpreting the results in subsequent systems in mammalian cells. This review describes the primary findings on the nature of ionizing radiation-induced mutagenesis in the N. crassa ad-3 system and the parallel observations made years later in mammalian cells.

Comparison of secondary neutron dose in proton therapy resulting from the use of a tungsten alloy MLC or a brass collimator system.

PubMed

Diffenderfer, Eric S; Ainsley, Christopher G; Kirk, Maura L; McDonough, James E; Maughan, Richard L

2011-11-01

To apply the dual ionization chamber method for mixed radiation fields to an accurate comparison of the secondary neutron dose arising from the use of a tungsten alloy multileaf collimator (MLC) as opposed to a brass collimator system for defining the shape of a therapeutic proton field. Hydrogenous and nonhydrogenous ionization chambers were constructed with large volumes to enable measurements of absorbed doses below 10(-4) Gy in mixed radiation fields using the dual ionization chamber method for mixed-field dosimetry. Neutron dose measurements were made with a nominal 230 MeV proton beam incident on a closed tungsten alloy MLC and a solid brass block. The chambers were cross-calibrated against a (60)Co-calibrated Farmer chamber in water using a 6 MV x-ray beam and Monte Carlo simulations were performed to account for variations in ionization chamber response due to differences in secondary neutron energy spectra. The neutron and combined proton plus γ-ray absorbed doses are shown to be nearly equivalent downstream from either a closed tungsten alloy MLC or a solid brass block. At 10 cm downstream from the distal edge of the collimating material the neutron dose from the closed MLC was (5.3 ± 0.4) × 10(- 5) Gy/Gy. The neutron dose with brass was (6.4 ± 0.7) × 10(- 5) Gy/Gy. Further from the secondary neutron source, at 50 cm, the neutron doses remain close for both the MLC and brass block at (6.9 ± 0.6) × 10(- 6) Gy/Gy and (6.3 ± 0.7) × 10(- 6) Gy/Gy, respectively. The dual ionization chamber method is suitable for measuring secondary neutron doses resulting from proton irradiation. The results of measurements downstream from a closed tungsten alloy MLC and a brass block indicate that, even in an overly pessimistic worst-case scenario, secondary neutron production in a tungsten alloy MLC leads to absorbed doses that are nearly equivalent to those seen from brass collimators. Therefore, the choice of tungsten alloy in constructing the leaves of a proton MLC is appropriate, and does not lead to a substantial increase in the secondary neutron dose to the patient compared to that generated in a brass collimator.

Multiple Testing, Cumulative Radiation Dose, and Clinical Indications in Patients Undergoing Myocardial Perfusion Imaging

PubMed Central

Einstein, Andrew J.; Weiner, Shepard D.; Bernheim, Adam; Kulon, Michal; Bokhari, Sabahat; Johnson, Lynne L.; Moses, Jeffrey W.; Balter, Stephen

2013-01-01

Context Myocardial perfusion imaging (MPI) is the single medical test with the highest radiation burden to the US population. While many patients undergoing MPI receive repeat MPI testing, or additional procedures involving ionizing radiation, no data are available characterizing their total longitudinal radiation burden and relating radiation burden with reasons for testing. Objective To characterize procedure counts, cumulative estimated effective doses of radiation, and clinical indications, for patients undergoing MPI. Design, Setting, Patients Retrospective cohort study evaluating, for 1097 consecutive patients undergoing index MPI during the first 100 days of 2006 at Columbia University Medical Center, all preceding medical imaging procedures involving ionizing radiation undergone beginning October 1988, and all subsequent procedures through June 2008, at that center. Main Outcome Measures Cumulative estimated effective dose of radiation, number of procedures involving radiation, and indications for testing. Results Patients underwent a median (interquartile range, mean) of 15 (6–32, 23.9) procedures involving radiation exposure; 4 (2–8, 6.5) were high-dose (≥3 mSv, i.e. one year's background radiation), including 1 (1–2, 1.8) MPI studies per patient. 31% of patients received cumulative estimated effective dose from all medical sources >100mSv. Multiple MPIs were performed in 39% of patients, for whom cumulative estimated effective dose was 121 (81–189, 149) mSv. Men and whites had higher cumulative estimated effective doses, and there was a trend towards men being more likely to undergo multiple MPIs than women (40.8% vs. 36.6%, Odds ratio 1.29, 95% confidence interval 0.98–1.69). Over 80% of initial and 90% of repeat MPI exams were performed in patients with known cardiac disease or symptoms consistent with it. Conclusion In this institution, multiple testing with MPI was very common, and in many patients associated with very high cumulative estimated doses of radiation. PMID:21078807

Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleiman, Norman Jay

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

Properties of a commercial PTW-60019 synthetic diamond detector for the dosimetry of small radiotherapy beams.

PubMed

Lárraga-Gutiérrez, José Manuel; Ballesteros-Zebadúa, Paola; Rodríguez-Ponce, Miguel; García-Garduño, Olivia Amanda; de la Cruz, Olga Olinca Galván

2015-01-21

A CVD based radiation detector has recently become commercially available from the manufacturer PTW-Freiburg (Germany). This detector has a sensitive volume of 0.004 mm(3), a nominal sensitivity of 1 nC Gy(-1) and operates at 0 V. Unlike natural diamond based detectors, the CVD diamond detector reports a low dose rate dependence. The dosimetric properties investigated in this work were dose rate, angular dependence and detector sensitivity and linearity. Also, percentage depth dose, off-axis dose profiles and total scatter ratios were measured and compared against equivalent measurements performed with a stereotactic diode. A Monte Carlo simulation was carried out to estimate the CVD small beam correction factors for a 6 MV photon beam. The small beam correction factors were compared with those obtained from stereotactic diode and ionization chambers in the same irradiation conditions The experimental measurements were performed in 6 and 15 MV photon beams with the following square field sizes: 10 × 10, 5 × 5, 4 × 4, 3 × 3, 2 × 2, 1.5 × 1.5, 1 × 1 and 0.5 × 0.5 cm. The CVD detector showed an excellent signal stability (<0.2%) and linearity, negligible dose rate dependence (<0.2%) and lower response angular dependence. The percentage depth dose and off-axis dose profiles measurements were comparable (within 1%) to the measurements performed with ionization chamber and diode in both conventional and small radiotherapy beams. For the 0.5 × 0.5 cm, the measurements performed with the CVD detector showed a partial volume effect for all the dosimetric quantities measured. The Monte Carlo simulation showed that the small beam correction factors were close to unity (within 1.0%) for field sizes ≥1 cm. The synthetic diamond detector had high linearity, low angular and negligible dose rate dependence, and its response was energy independent within 1% for field sizes from 1.0 to 5.0 cm. This work provides new data showing the performance of the CVD detector compared against a high spatial resolution diode. It also presents a comparison of the CVD small beam correction factors with those of diode and ionization chamber for a 6 MV photon beam.

Estimation of the influence of radical effect in the proton beams using a combined approach with physical data and gel data

NASA Astrophysics Data System (ADS)

Haneda, K.

2016-04-01

The purpose of this study was to estimate an impact on radical effect in the proton beams using a combined approach with physical data and gel data. The study used two dosimeters: ionization chambers and polymer gel dosimeters. Polymer gel dosimeters have specific advantages when compared to other dosimeters. They can measure chemical reaction and they are at the same time a phantom that can map in three dimensions continuously and easily. First, a depth-dose curve for a 210 MeV proton beam measured using an ionization chamber and a gel dosimeter. Second, the spatial distribution of the physical dose was calculated by Monte Carlo code system PHITS: To verify of the accuracy of Monte Carlo calculation, and the calculation results were compared with experimental data of the ionization chamber. Last, to evaluate of the rate of the radical effect against the physical dose. The simulation results were compared with the measured depth-dose distribution and showed good agreement. The spatial distribution of a gel dose with threshold LET value of proton beam was calculated by the same simulation code. Then, the relative distribution of the radical effect was calculated from the physical dose and gel dose. The relative distribution of the radical effect was calculated at each depth as the quotient of relative dose obtained using physical and gel dose. The agreement between the relative distributions of the gel dosimeter and Radical effect was good at the proton beams.

Recombination in liquid-filled ionization chambers beyond the Boag limit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brualla-González, L.; Roselló, J.

Purpose: The high mass density and low mobilities of charge carriers can cause important recombination in liquid-filled ionization chambers (LICs). Saturation correction methods have been proposed for LICs. Correction methods for pulsed irradiation are based on Boag equation. However, Boag equation assumes that the charge ionized by one pulse is fully collected before the arrival of the next pulse. This condition does not hold in many clinical beams where the pulse repetition period may be shorter than the charge collection time, causing overlapping between charge carriers ionized by different pulses, and Boag equation is not applicable there. In this work,more » the authors present an experimental and numerical characterization of collection efficiencies in LICs beyond the Boag limit, with overlapping between charge carriers ionized by different pulses. Methods: The authors have studied recombination in a LIC array for different dose-per-pulse, pulse repetition frequency, and polarization voltage values. Measurements were performed in a Truebeam Linac using FF and FFF modalities. Dose-per-pulse and pulse repetition frequency have been obtained by monitoring the target current with an oscilloscope. Experimental collection efficiencies have been obtained by using a combination of the two-dose-rate method and ratios to the readout of a reference chamber (CC13, IBA). The authors have also used numerical simulation to complement the experimental data. Results: The authors have found that overlap significantly increases recombination in LICs, as expected. However, the functional dependence of collection efficiencies on the dose-per-pulse does not change (a linear dependence has been observed in the near-saturation region for different degrees of overlapping, the same dependence observed in the nonoverlapping scenario). On the other hand, the dependence of collection efficiencies on the polarization voltage changes in the overlapping scenario and does not follow that of Boag equation, the reason being that changing the polarization voltage also affects the charge collection time, thus changing the amount of overlapping. Conclusions: These results have important consequences for saturation correction methods for LICs. On one hand, the two-dose-rate method, which relies on the functional dependence of the collection efficiencies on dose-per-pulse, can also be used in the overlapping situation, provided that the two measurements needed to feed the method are performed at the same pulse repetition frequency (monitor unit rate). This result opens the door to computing collection efficiencies in LICs in many clinical setups where charge overlap in the LIC exists. On the other hand, correction methods based on the voltage-dependence of Boag equation like the three-voltage method or the modified two-voltage method will not work in the overlapping scenario due to the different functional dependence of collection efficiencies on the polarization voltage.« less

Fitness costs of increased cataract frequency and cumulative radiation dose in natural mammalian populations from Chernobyl.

PubMed

Lehmann, Philipp; Boratyński, Zbyszek; Mappes, Tapio; Mousseau, Timothy A; Møller, Anders P

2016-01-27

A cataract is a clouding of the lens that reduces light transmission to the retina, and it decreases the visual acuity of the bearer. The prevalence of cataracts in natural populations of mammals, and their potential ecological significance, is poorly known. Cataracts have been reported to arise from high levels of oxidative stress and a major cause of oxidative stress is ionizing radiation. We investigated whether elevated frequencies of cataracts are found in eyes of bank voles Myodes glareolus collected from natural populations in areas with varying levels of background radiation in Chernobyl. We found high frequencies of cataracts in voles collected from different areas in Chernobyl. The frequency of cataracts was positively correlated with age, and in females also with the accumulated radiation dose. Furthermore, the number of offspring in female voles was negatively correlated with cataract severity. The results suggest that cataracts primarily develop as a function of ionizing background radiation, most likely as a plastic response to high levels of oxidative stress. It is therefore possible that the elevated levels of background radiation in Chernobyl affect the ecology and fitness of local mammals both directly through, for instance, reduced fertility and indirectly, through increased cataractogenesis.

Tolerance of anhydrobiotic eggs of the Tardigrade Ramazzottius varieornatus to extreme environments.

PubMed

Horikawa, Daiki D; Yamaguchi, Ayami; Sakashita, Tetsuya; Tanaka, Daisuke; Hamada, Nobuyuki; Yukuhiro, Fumiko; Kuwahara, Hirokazu; Kunieda, Takekazu; Watanabe, Masahiko; Nakahara, Yuichi; Wada, Seiichi; Funayama, Tomoo; Katagiri, Chihiro; Higashi, Seigo; Yokobori, Shin-Ichi; Kuwabara, Mikinori; Rothschild, Lynn J; Okuda, Takashi; Hashimoto, Hirofumi; Kobayashi, Yasuhiko

2012-04-01

Tardigrades are tiny (less than 1 mm in length) invertebrate animals that have the potential to survive travel to other planets because of their tolerance to extreme environmental conditions by means of a dry ametabolic state called anhydrobiosis. While the tolerance of adult tardigrades to extreme environments has been reported, there are few reports on the tolerance of their eggs. We examined the ability of hydrated and anhydrobiotic eggs of the tardigrade Ramazzottius varieornatus to hatch after exposure to ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. We previously reported that there was a similar pattern of tolerance against ionizing radiation between hydrated and anhydrobiotic adults. In contrast, anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at either -196°C or +50°C hatched successfully, but all the hydrated eggs failed to hatch. After exposure to high-vacuum conditions (5.3×10(-4) Pa to 6.2×10(-5) Pa), the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.

Radiology Residents' Awareness about Ionizing Radiation Doses in Imaging Studies and Their Cancer Risk during Radiological Examinations

PubMed Central

Divrik Gökçe, Senem; Coşkun, Melek

2012-01-01

Objective Imaging methods that use ionizing radiation have been more frequent in various medical fields with advances in imaging technology. The aim of our study was to make residents be aware of the radiation dose they are subjected to when they conduct radiological imaging methods, and of cancer risk. Materials and Methods A total of 364 residents participated in this descriptive study which was conducted during the period between October, 2008 and January, 2009. The questionnaires were completed under strict control on a one-to-one basis from each department. A χ2-test was used for the evaluation of data obtained. Results Only 7% of residents correctly answered to the question about the ionizing radiation dose of a posteroanterior (PA) chest X-ray. The question asking about the equivalent number of PA chest X-rays to the ionizing dose of a brain CT was answered correctly by 24% of residents; the same question regarding abdominal CT was answered correctly by 16% of residents, thorax CT by 16%, thyroid scintigraphy by 15%, intravenous pyelography by 9%, and lumbar spine radiography by 2%. The risk of developing a cancer throughout lifetime by a brain and abdominal CT were 33% and 28%, respectively. Conclusion Radiologic residents should have updated knowledge about radiation dose content and attendant cancer risks of various radiological imaging methods during both basic medical training period and following practice period. PMID:22438688

Morphological and transcriptional response of an anhydrobiotic insect to ionizing radiation and desiccation: steps forward in understanding molecular background of extreme radioresistance in higher eukaryotes

NASA Astrophysics Data System (ADS)

Gusev, Oleg; Novikova, Nataliya; Sychev, Vladimir; Okuda, Takashi; Kikawada, Takahiro; Sakashita, Tetsuya; Mukae, Kyosuke

2012-07-01

Life in extreme or drastically changing environments in many cases leads to evolutionary evolvement of mechanisms of cross-resistance to different abiotic stresses, often never actually faced by the organism in its natural habitat. Larvae of the sleeping chironomidPolypedilum vanderplanki (Diptera) are able to resist complete desiccation and in the dry form survive under excess of various abiotic stresses, including exposure to space environment. One of the most intriguing features of the anhydrobiotic larvae is resistance to extremely high doses of different types of ionizing radiation. To understand the cross-tolerance mechanism, we have analyzed the structural changes in the nuclear DNA using transmission electron microscopy and DNA comet assays in relation to anhydrobiosis and radiation. We find that dehydration causes alterations in chromatin structure and a severe fragmentation of nuclear DNA in the cells of the larvae despite successful anhydrobiosis. The DNA fragmentation level and the recovery of DNA integrity in the rehydrated after anhydrobiosis larvae were similar to those of hydrated larvae irradiated with 70 Gy of high-linear energy transfer (LET) ions (4He+). In comparison, low-LET radiation (gamma rays) of the same dose causes less initial damage to the larvae, and recovery of DNA repair is complete within 24 h. Genome-wide analysis of mRNA expression in the larvae revealed that a large group of genes (including antioxidants, anhydrobiosis-specific biomolecules and protein-reparation enzymes) showed a similar patterns of activity in response to both desiccation and ionizing radiation. We conclude that t one of the factors explaining the relationship between the resistance to ionizing radiation and the ability to undergo anhydrobiosis in the sleeping chironomid would be an adaptation to desiccation-inflicted proteins and nuclear DNA damage.

Comparative transcriptome analysis of rice seedlings induced by different doses of heavy ion radiation

NASA Astrophysics Data System (ADS)

Zhao, Qian; Sun, Yeqing; Wang, Wei

2016-07-01

Highly ionizing radiation (HZE) in space is considered as a main factor causing biological effects on plant seeds. To investigate the different effects on genome-wide gene expression of low-dose and high-dose ion radiation, we carried out ground-base carbon particle HZE experiments with different cumulative doses (0Gy, 0.2Gy, 2Gy) to rice seeds and then performed comparative transcriptome analysis of the rice seedlings. We identified a total of 2551 and 1464 differentially expressed genes (DEGs) in low-dose and high-dose radiation groups, respectively. Gene ontology analyses indicated that low-dose and high-dose ion radiation both led to multiple physiological and biochemical activities changes in rice. By Gene Ontology analyses, the results showed that only one process-oxidation reduction process was enriched in the biological process category after high-dose ion radiation, while more processes such as response to biotic stimulus, heme binding, tetrapyrrole binding, oxidoreductase activity, catalytic activity and oxidoreductase activity were significantly enriched after low-dose ion radiation. The results indicated that the rice plants only focused on the process of oxidation reduction to response to high-dose ion radiation, whereas it was a coordination of multiple biological processes to response to low-dose ion radiation. To elucidate the transcriptional regulation of radiation stress-responsive genes, we identified several DEGs-encoding TFs. AP2/EREBP, bHLH, C2H2, MYB and WRKY TF families were altered significantly in response to ion radiation. Mapman analysis speculated that the biological effects on rice seedlings caused by the radiation stress might share similar mechanisms with the biotic stress. Our findings highlight important alterations in the expression of radiation response genes, metabolic pathways, and TF-encoding genes in rice seedlings exposed to low-dose and high-dose ion radiation.

SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supanich, MP

2015-06-15

Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in themore » central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG.« less

Acceleration of atherogenesis in ApoE-/- mice exposed to acute or low-dose-rate ionizing radiation.

PubMed

Mancuso, Mariateresa; Pasquali, Emanuela; Braga-Tanaka, Ignacia; Tanaka, Satoshi; Pannicelli, Alessandro; Giardullo, Paola; Pazzaglia, Simonetta; Tapio, Soile; Atkinson, Michael J; Saran, Anna

2015-10-13

There is epidemiological evidence for increased non-cancer mortality, primarily due to circulatory diseases after radiation exposure above 0.5 Sv. We evaluated the effects of chronic low-dose rate versus acute exposures in a murine model of spontaneous atherogenesis. Female ApoE-/- mice (60 days) were chronically irradiated for 300 days with gamma rays at two different dose rates (1 mGy/day; 20 mGy/day), with total accumulated doses of 0.3 or 6 Gy. For comparison, age-matched ApoE-/- females were acutely exposed to the same doses and sacrificed 300 days post-irradiation. Mice acutely exposed to 0.3 or 6 Gy showed increased atherogenesis compared to age-matched controls, and this effect was persistent. When the same doses were delivered at low dose rate over 300 days, we again observed a significant impact on global development of atherosclerosis, although at 0.3 Gy effects were limited to the descending thoracic aorta. Our data suggest that a moderate dose of 0.3 Gy can have persistent detrimental effects on the cardiovascular system, and that a high dose of 6 Gy poses high risks at both high and low dose rates. Our results were clearly nonlinear with dose, suggesting that lower doses may be more damaging than predicted by a linear dose response.

Survival of thermophilic and hyperthermophilic microorganisms after exposure to UV-C, ionizing radiation and desiccation.

PubMed

Beblo, Kristina; Douki, Thierry; Schmalz, Gottfried; Rachel, Reinhard; Wirth, Reinhard; Huber, Harald; Reitz, Günther; Rettberg, Petra

2011-11-01

In this study, we investigated the ability of several (hyper-) thermophilic Archaea and phylogenetically deep-branching thermophilic Bacteria to survive high fluences of monochromatic UV-C (254 nm) and high doses of ionizing radiation, respectively. Nine out of fourteen tested microorganisms showed a surprisingly high tolerance against ionizing radiation, and two species (Aquifex pyrophilus and Ignicoccus hospitalis) were even able to survive 20 kGy. Therefore, these species had a comparable survivability after exposure to ionizing radiation such as Deinococcus radiodurans. In contrast, there was nearly no difference in survival of the tested strains after exposure to UV-C under anoxic conditions. If the cells had been dried in advance of UV-C irradiation, they were more sensitive to UV-C radiation compared with cells irradiated in liquid suspension; this effect could be reversed by the addition of protective material like sulfidic ores before irradiation. By exposure to UV-C, photoproducts were formed in the DNA of irradiated Archaea and Bacteria. The distribution of the main photoproducts was species specific, but the amount of the photoproducts was only partly dependent on the applied fluence. Overall, our results show that tolerance to radiation seems to be a common phenomenon among thermophilic and hyperthermophilic microorganisms.

Beneficial effects of calcitriol on hypertension, glucose intolerance, impairment of endothelium-dependent vascular relaxation, and visceral adiposity in fructose-fed hypertensive rats.

PubMed

Chou, Chu-Lin; Pang, Cheng-Yoong; Lee, Tony J F; Fang, Te-Chao

2015-01-01

Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group). Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose) for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L). These results suggest a protective role of calcitriol treatment on endothelial function, glucose tolerance, and visceral adiposity in fructose-fed rats.

Leukemia and brain tumors among children after radiation exposure from CT scans: design and methodological opportunities of the Dutch Pediatric CT Study.

PubMed

Meulepas, Johanna M; Ronckers, Cécile M; Smets, Anne M J B; Nievelstein, Rutger A J; Jahnen, Andreas; Lee, Choonsik; Kieft, Mariëtte; Laméris, Johan S; van Herk, Marcel; Greuter, Marcel J W; Jeukens, Cécile R L P N; van Straten, Marcel; Visser, Otto; van Leeuwen, Flora E; Hauptmann, Michael

2014-04-01

Computed tomography (CT) scans are indispensable in modern medicine; however, the spectacular rise in global use coupled with relatively high doses of ionizing radiation per examination have raised radiation protection concerns. Children are of particular concern because they are more sensitive to radiation-induced cancer compared with adults and have a long lifespan to express harmful effects which may offset clinical benefits of performing a scan. This paper describes the design and methodology of a nationwide study, the Dutch Pediatric CT Study, regarding risk of leukemia and brain tumors in children after radiation exposure from CT scans. It is a retrospective record-linkage cohort study with an expected number of 100,000 children who received at least one electronically archived CT scan covering the calendar period since the introduction of digital archiving until 2012. Information on all archived CT scans of these children will be obtained, including date of examination, scanned body part and radiologist's report, as well as the machine settings required for organ dose estimation. We will obtain cancer incidence by record linkage with external databases. In this article, we describe several approaches to the collection of data on archived CT scans, the estimation of radiation doses and the assessment of confounding. The proposed approaches provide useful strategies for data collection and confounder assessment for general retrospective record-linkage studies, particular those using hospital databases on radiological procedures for the assessment of exposure to ionizing or non-ionizing radiation.

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

NASA Astrophysics Data System (ADS)

Watson, Peter G. F.; Popovic, Marija; Seuntjens, Jan

2018-01-01

Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, CQ , to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work CQ was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that CQ was sensitive to the chamber plate separation tolerance, with differences of up to 15%. CQ was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, CQ was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

Gamma radiation field intensity meter

DOEpatents

Thacker, Louis H.

1994-01-01

A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

Gamma radiation field intensity meter

DOEpatents

Thacker, Louis H.

1995-01-01

A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

Comparative Study between Measurement Data and Treatment Planning System (TPS) in Small Fields for High Energy Photon Beams.

PubMed

El Shahat, Khaled; El Saeid, Aziza; Attalla, Ehab; Yassin, Adel

2014-01-01

To achieve tumor control for radiotherapy, a dose distribution is planned which has a good chance of sterilizing all cancer cells without causing unacceptable normal tissue complications. The aim of the present study was to achieve an accurate calculation of dose for small field dimensions and perform this by evaluating the accuracy of planning system calculation. This will be compared with real measurement of dose for the same small field dimensions using different detectors. Practical work was performed in two steps: (i) determination of the physical factors required for dose estimation measured by three ionization chambers and calculated by treatment planning system (TPS) based on the latest technical report series (IAEATRS-398) and (ii) comparison of the calculated and measured data. Our data analysis for small field is irradiated by photon energy matched with the data obtained from the ionization chambers and the treatment planning system. Radiographic films were used as an additional detector for the obtained data and showed matching with TPS calculation. It can be concluded that studied small field dimensions were averaged 6% and 4% for 6 MV and 15 MV, respectively. Radiographic film measurements showed a variation in results within ±2% than TPS calculation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowe, Xiu R; Bhattacharya, Sanchita; Marchetti, Francesco

Understanding the cognitive and behavioral consequences of brain exposures to low-dose ionizing radiation has broad relevance for health risks from medical radiation diagnostic procedures, radiotherapy, environmental nuclear contamination, as well as earth orbit and space missions. Analyses of transcriptome profiles of murine brain tissue after whole-body radiation showed that low-dose exposures (10 cGy) induced genes not affected by high dose (2 Gy), and low-dose genes were associated with unique pathways and functions. The low-dose response had two major components: pathways that are consistently seen across tissues, and pathways that were brain tissue specific. Low-dose genes clustered into a saturated networkmore » (p < 10{sup -53}) containing mostly down-regulated genes involving ion channels, long-term potentiation and depression, vascular damage, etc. We identified 9 neural signaling pathways that showed a high degree of concordance in their transcriptional response in mouse brain tissue after low-dose radiation, in the aging human brain (unirradiated), and in brain tissue from patients with Alzheimer's disease. Mice exposed to high-dose radiation did not show these effects and associations. Our findings indicate that the molecular response of the mouse brain within a few hours after low-dose irradiation involves the down-regulation of neural pathways associated with cognitive dysfunctions that are also down regulated in normal human aging and Alzheimer's disease.« less

Absorbed Dose and Dose Equivalent Calculations for Modeling Effective Dose

NASA Technical Reports Server (NTRS)

Welton, Andrew; Lee, Kerry

2010-01-01

While in orbit, Astronauts are exposed to a much higher dose of ionizing radiation than when on the ground. It is important to model how shielding designs on spacecraft reduce radiation effective dose pre-flight, and determine whether or not a danger to humans is presented. However, in order to calculate effective dose, dose equivalent calculations are needed. Dose equivalent takes into account an absorbed dose of radiation and the biological effectiveness of ionizing radiation. This is important in preventing long-term, stochastic radiation effects in humans spending time in space. Monte carlo simulations run with the particle transport code FLUKA, give absorbed and equivalent dose data for relevant shielding. The shielding geometry used in the dose calculations is a layered slab design, consisting of aluminum, polyethylene, and water. Water is used to simulate the soft tissues that compose the human body. The results obtained will provide information on how the shielding performs with many thicknesses of each material in the slab. This allows them to be directly applicable to modern spacecraft shielding geometries.

New approaches in clinical application of laser-driven ionizing radiation

NASA Astrophysics Data System (ADS)

Hideghéty, Katalin; Szabó, Rita Emilia; Polanek, Róbert; Szabó, Zoltán.; Brunner, Szilvia; Tőkés, Tünde

2017-05-01

The planned laser-driven ionizing beams (photon, very high energy electron, proton, carbon ion) at laser facilities have the unique property of ultra-high dose rate (>Gy/s-10), short pulses, and at ELI-ALPS high repetition rate, carry the potential to develop novel laser-driven methods towards compact hospital-based clinical application. The enhanced flexibility in particle and energy selection, the high spatial and time resolution and extreme dose rate could be highly beneficial in radiotherapy. These approaches may increase significantly the therapeutic index over the currently available advanced radiation oncology methods. We highlight two nuclear reactionbased binary modalities and the planned radiobiology research. Boron Neutron Capture Therapy is an advanced cell targeted modality requiring 10B enriched boron carrier and appropriate neutron beam. The development of laser-based thermal and epithermal neutron source with as high as 1010 fluence rate could enhance the research activity in this promising field. Boron-Proton Fusion reaction is as well as a binary approach, where 11B containing compounds are accumulated into the cells, and the tumour selectively irradiated with protons. Due to additional high linear energy transfer alpha particle release of the BPFR and the maximum point of the Bragg-peak is increased, which result in significant biological effect enhancement. Research at ELI-ALPS on detection of biological effect differences of modified or different quality radiation will be presented using recently developed zebrafish embryo and rodent models.

Radiation measurements aboard Spacelab 1

NASA Technical Reports Server (NTRS)

Benton, E. V.; Almasi, J.; Cassou, R.; Frank, A.; Henke, R. P.; Rowe, V.; Parnell, T. A.; Schopper, E.

1984-01-01

The radiation environment inside Spacelab 1 was measured by a set of passive radiation detectors distributed throughout the volume inside the module, in the access tunnel, and outside on the pallet. Measurements of the low linear energy transfer (LET) component obtained from the thermoluminescence detectors ranged from 102 to 190 millirads, yielding an average low LET dose rate of 11.2 millirads/day inside the module, about twice the low LET dose rate measured on previous flights of the Space Shuttle. Because of the higher inclination of the orbit (57 versus 28.5 deg for previous Shuttle flights), substantial fluxes of highly ionizing high charge and energy galactic cosmic ray particles were observed, yielding an overall average mission dose-equivalent of about 150 millirems, more than three times higher than that measured on previous Shuttle missions.

Hormetic Response to Low-Dose Radiation: Focus on the Immune System and Its Clinical Implications

PubMed Central

Cui, Jiuwei; Yang, Guozi; Pan, Zhenyu; Zhao, Yuguang; Liang, Xinyue; Li, Wei; Cai, Lu

2017-01-01

The interrelationship between ionizing radiation and the immune system is complex, multifactorial, and dependent on radiation dose/quality and immune cell type. High-dose radiation usually results in immune suppression. On the contrary, low-dose radiation (LDR) modulates a variety of immune responses that have exhibited the properties of immune hormesis. Although the underlying molecular mechanism is not fully understood yet, LDR has been used clinically for the treatment of autoimmune diseases and malignant tumors. These advancements in preclinical and clinical studies suggest that LDR-mediated immune modulation is a well-orchestrated phenomenon with clinical potential. We summarize recent developments in the understanding of LDR-mediated immune modulation, with an emphasis on its potential clinical applications. PMID:28134809

Effective radiation exposure evaluation during a one year follow-up of urolithiasis patients after extracorporeal shock wave lithotripsy.

PubMed

Kaynar, Mehmet; Tekinarslan, Erdem; Keskin, Suat; Buldu, İbrahim; Sönmez, Mehmet Giray; Karatag, Tuna; Istanbulluoglu, Mustafa Okan

2015-01-01

To determine and evaluate the effective radiation exposure during a one year follow-up of urolithiasis patients following the SWL (extracorporeal shock wave lithotripsy) treatment. Total Effective Radiation Exposure (ERE) doses for each of the 129 patients: 44 kidney stone patients, 41 ureter stone patients, and 44 multiple stone location patients were calculated by adding up the radiation doses of each ionizing radiation session including images (IVU, KUB, CT) throughout a one year follow-up period following the SWL. Total mean ERE values for the kidney stone group was calculated as 15, 91 mSv (5.10-27.60), for the ureter group as 13.32 mSv (5.10-24.70), and in the multiple stone location group as 27.02 mSv (9.41-54.85). There was no statistically significant differences between the kidney and ureter groups in terms of the ERE dose values (p = 0.221) (p >0.05). In the comparison of the kidney and ureter stone groups with the multiple stone location group; however, there was a statistically significant difference (p = 0.000) (p <0.05). ERE doses should be a factor to be considered right at the initiation of any diagnostic and/or therapeutic procedure. Especially in the case of multiple stone locations, due to the high exposure to ionized radiation, different imaging modalities with low dose and/or totally without a dose should be employed in the diagnosis, treatment, and follow-up bearing the aim to optimize diagnosis while minimizing the radiation dose as much as possible.

Current methods of monitoring radiation exposure from CT.

PubMed

Talati, Ronak K; Dunkin, Jared; Parikh, Shrujal; Moore, William H

2013-09-01

Increased public and regulatory scrutiny of imaging-related radiation exposure requires familiarity with current dose-monitoring techniques and best practices. CT-related ionizing radiation exposure has been cited as the largest and fastest growing source of population-wide iatrogenic ionizing radiation exposure. Upcoming federal regulations require imaging centers to familiarize themselves with available dose-monitoring techniques and implement comprehensive strategies to track patient dose, with particular emphasis on CT. Because of institution-specific and vendor-specific technologies, there are significant barriers to adoption and implementation. In this article, the authors outline the core components of a universal dose-monitoring strategy and detail a few of the many available commercial platforms. In addition, the authors introduce a cloud-based hybrid model dose-tracking system with the goal of rapid implementation, multicenter scalability, real-time dose feedback for technologists, cumulative dose monitoring, and optional dose communication to patients and into the record; doing so results in improved patient loyalty, referring physician satisfaction, and opportunity for repeat business. Copyright © 2013 American College of Radiology. All rights reserved.

2D convolution kernels of ionization chambers used for photon-beam dosimetry in magnetic fields: the advantage of small over large chamber dimensions

NASA Astrophysics Data System (ADS)

Khee Looe, Hui; Delfs, Björn; Poppinga, Daniela; Harder, Dietrich; Poppe, Björn

2018-04-01

This study aims at developing an optimization strategy for photon-beam dosimetry in magnetic fields using ionization chambers. Similar to the familiar case in the absence of a magnetic field, detectors should be selected under the criterion that their measured 2D signal profiles M(x,y) approximate the absorbed dose to water profiles D(x,y) as closely as possible. Since the conversion of D(x,y) into M(x,y) is known as the convolution with the ‘lateral dose response function’ K(x-ξ, y-η) of the detector, the ideal detector would be characterized by a vanishing magnetic field dependence of this convolution kernel (Looe et al 2017b Phys. Med. Biol. 62 5131–48). The idea of the present study is to find out, by Monte Carlo simulation of two commercial ionization chambers of different size, whether the smaller chamber dimensions would be instrumental to approach this aim. As typical examples, the lateral dose response functions in the presence and absence of a magnetic field have been Monte-Carlo modeled for the new commercial ionization chambers PTW 31021 (‘Semiflex 3D’, internal radius 2.4 mm) and PTW 31022 (‘PinPoint 3D’, internal radius 1.45 mm), which are both available with calibration factors. The Monte-Carlo model of the ionization chambers has been adjusted to account for the presence of the non-collecting part of the air volume near the guard ring. The Monte-Carlo results allow a comparison between the widths of the magnetic field dependent photon fluence response function K M(x-ξ, y-η) and of the lateral dose response function K(x-ξ, y-η) of the two chambers with the width of the dose deposition kernel K D(x-ξ, y-η). The simulated dose and chamber signal profiles show that in small photon fields and in the presence of a 1.5 T field the distortion of the chamber signal profile compared with the true dose profile is weakest for the smaller chamber. The dose responses of both chambers at large field size are shown to be altered by not more than 2% in magnetic fields up to 1.5 T for all three investigated chamber orientations.

Assessing the dose values received by patients during conventional radiography X-ray examinations and the technical condition of the equipment used for this purpose.

PubMed

Bekas, Marcin; Pachocki, Krzysztof A; Waśniewska, Elżbieta; Bogucka, Dagmara; Magiera, Andrzej

2014-01-01

X-ray examination is associated with patient exposure to ionizing radiation. Dose values depend on the type of medical procedure used, the X-ray unit technical condition and exposure conditions selected. The aim of this study was to determine the dose value received by patients during certain conventional radiography X-ray examinations and to assess the technical condition of medical equipment used for this purpose. The study covered the total number of 118 conventional diagnostic X-ray units located in the Masovian Voivodeship. The methodology used to assess the conventional diagnostic X-ray unit technical condition and the measurement of the radiation dose rate received by patients are based on test procedures developed by the Department of Radiation Protection and Radiobiology of the National Institute of Public Health - National Institute of Hygiene (Warszawa, Poland) accredited for compliance with PN-EN 17025 standard by the Polish Centre for Accreditation. It was found that 84.7% of X-ray units fully meet the criteria set out in the Polish legislation regarding the safe use of ionizing radiation in medicine, while 15.3% of the units do not meet some of them. The broadest dose value range was recorded for adult patients. Particularly, during lateral (LATl) lumbar spine radiography the recorded entrance surface dose (ESD) values ranged from 283.5 to 7827 µGy (mean: 2183.3 µGy). It is absolutely necessary to constantly monitor the technical condition of all X-ray units, because it affects population exposure to ionizing radiation. Furthermore, it is essential to raise radiographers' awareness of the effects that ionizing radiation exposure can have on the human body.

Extrapolation of the dna fragment-size distribution after high-dose irradiation to predict effects at low doses

NASA Technical Reports Server (NTRS)

Ponomarev, A. L.; Cucinotta, F. A.; Sachs, R. K.; Brenner, D. J.; Peterson, L. E.

2001-01-01

The patterns of DSBs induced in the genome are different for sparsely and densely ionizing radiations: In the former case, the patterns are well described by a random-breakage model; in the latter, a more sophisticated tool is needed. We used a Monte Carlo algorithm with a random-walk geometry of chromatin, and a track structure defined by the radial distribution of energy deposition from an incident ion, to fit the PFGE data for fragment-size distribution after high-dose irradiation. These fits determined the unknown parameters of the model, enabling the extrapolation of data for high-dose irradiation to the low doses that are relevant for NASA space radiation research. The randomly-located-clusters formalism was used to speed the simulations. It was shown that only one adjustable parameter, Q, the track efficiency parameter, was necessary to predict DNA fragment sizes for wide ranges of doses. This parameter was determined for a variety of radiations and LETs and was used to predict the DSB patterns at the HPRT locus of the human X chromosome after low-dose irradiation. It was found that high-LET radiation would be more likely than low-LET radiation to induce additional DSBs within the HPRT gene if this gene already contained one DSB.

Feasibility Study on Cardiac Arrhythmia Ablation Using High-Energy Heavy Ion Beams

NASA Astrophysics Data System (ADS)

Lehmann, H. Immo; Graeff, Christian; Simoniello, Palma; Constantinescu, Anna; Takami, Mitsuru; Lugenbiel, Patrick; Richter, Daniel; Eichhorn, Anna; Prall, Matthias; Kaderka, Robert; Fiedler, Fine; Helmbrecht, Stephan; Fournier, Claudia; Erbeldinger, Nadine; Rahm, Ann-Kathrin; Rivinius, Rasmus; Thomas, Dierk; Katus, Hugo A.; Johnson, Susan B.; Parker, Kay D.; Debus, Jürgen; Asirvatham, Samuel J.; Bert, Christoph; Durante, Marco; Packer, Douglas L.

2016-12-01

High-energy ion beams are successfully used in cancer therapy and precisely deliver high doses of ionizing radiation to small deep-seated target volumes. A similar noninvasive treatment modality for cardiac arrhythmias was tested here. This study used high-energy carbon ions for ablation of cardiac tissue in pigs. Doses of 25, 40, and 55 Gy were applied in forced-breath-hold to the atrioventricular junction, left atrial pulmonary vein junction, and freewall left ventricle of intact animals. Procedural success was tracked by (1.) in-beam positron-emission tomography (PET) imaging; (2.) intracardiac voltage mapping with visible lesion on ultrasound; (3.) lesion outcomes in pathohistolgy. High doses (40-55 Gy) caused slowing and interruption of cardiac impulse propagation. Target fibrosis was the main mediator of the ablation effect. In irradiated tissue, apoptosis was present after 3, but not 6 months. Our study shows feasibility to use high-energy ion beams for creation of cardiac lesions that chronically interrupt cardiac conduction.

Diagnostic medical imaging radiation exposure and risk of development of solid and hematologic malignancy.

PubMed

Fabricant, Peter D; Berkes, Marschall B; Dy, Christopher J; Bogner, Eric A

2012-05-01

Limiting patients' exposure to ionizing radiation during diagnostic imaging is of concern to patients and clinicians. Large single-dose exposures and cumulative exposures to ionizing radiation have been associated with solid tumors and hematologic malignancy. Although these associations have been a driving force in minimizing patients' exposure, significant risks are found when diagnoses are missed and subsequent treatment is withheld. Therefore, based on epidemiologic data obtained after nuclear and occupational exposures, dose exposure limits have been estimated. A recent collaborative effort between the US Food and Drug Administration and the American College of Radiology has provided information and tools that patients and imaging professionals can use to avoid unnecessary ionizing radiation scans and ensure use of the lowest feasible radiation dose necessary for studies. Further collaboration, research, and development should focus on producing technological advances that minimize individual study exposures and duplicate studies. This article outlines the research used to govern safe radiation doses, defines recent initiatives in decreasing radiation exposure, and provides orthopedic surgeons with techniques that may help decrease radiation exposure in their daily practice. Copyright 2012, SLACK Incorporated.

Ways of Use of Ionizing Radiation in the Manufacture of Bacterial Preparations; PUTI ISPOL'ZOVANIYA IONIZIRUYUSHCHEI RADIATSII V PROIZVODSTVE BAKTERIINYKH PREPARATOV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Troitskii, V.L.; Tumanyan, M.A. et al.

1959-10-31

Experiments are reported which give encouraging results for applications of ionizing radiations in the sterilization of vaccines, antitoxins, and serums for use in medical prophylaxis and treatment. A cobalt-60 gamma source was used. A dose of 1.5 Mr had a sterilizing effect, killing not only vegetative bacteria but sporeformers as well. Irradiation with sterilizing doses did not reduce the nutrient properties of meat media used for growth of bacteria of the intestinal group. The formation of diphtheria toxin proceeded on irradiated media the same as on nonirradiated. Irradiation did not reduce the antigenic or immunological properties of typhoid vaccines ormore » diphtheria and tetanus antitoxins. Serum products deteriorated after exposure to sterilizing doses but showed good tolerances to doses which killed vegetative forms of bacteria. It was concluded that ionizing radiation will prove practical for the preparation of many pharmaceutical products, the cold sterilization of nutrient broth, and the cold sterilization of the wastes from the manufacture of bacterial preparations. (C.H.)« less

THE EFFECT OF IONIZING RADIATION ON PREGNANCY AND FETAL DEVELOPMENT (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pobedinskii, N.M.

1961-01-01

A review is presented on the reactions of pregnant animais to radiation, the effect of ionizing radiation on the fetus and offspring of man and animal, the mechanism of the action of ionizing radiation on the fetus, and the protective action of agents such as mercamine and heroin. It is stressed that the effect of a dose of ionizing radiation varies with the stage of pregnancy at the time of irradiation (80 references). (TTT)

Disordered redox metabolism of brain cells in rats exposed to low doses of ionizing radiation or UHF electromagnetic radiation.

PubMed

Burlaka, A P; Druzhyna, M O; Vovk, A V; Lukin, S М

2016-12-01

To investigate the changes of redox-state of mammalian brain cells as the critical factor of initiation and formation of radiation damage of biological structures in setting of continuous exposure to low doses of ionizing radiation or fractionated ultra high frequency electromagnetic radiation (UHF EMR) at non-thermal levels. The influence of low-intensity ionizing radiation was studied on outbred female rats kept for 1.5 years in the Chernobyl accident zone. The effects of total EMR in the UHF band of non-thermal spectrum were investigated on Wistar rats. The rate of formation of superoxide radicals and the rate of NO synthesis in mitochondria were determined by the EPR. After exposure to ionizing or UHF radiation, the levels of ubisemiquinone in brain tissue of rats decreased by 3 and 1.8 times, respectively. The content of NO-FeS-protein complexes in both groups increased significantly (р < 0.05). In the conditions of ionizing or EMR the rates of superoxide radical generation in electron-transport chain of brain cell mitochondria increased by 1.5- and 2-fold, respectively (р < 0.05). In brain tissue of rats kept in the Chernobyl zone, significant increase of NO content was registered; similar effect was observed in rats treated with UHFR (р < 0.05). The detected changes in the electron transport chain of mitochondria of brain cells upon low-intensity irradiation or UHF EMR cause the metabolic reprogramming of cell mitochondria that increases the rate of superoxide radical generation and nitric oxide, which may initiate the development of neurodegenerative diseases and cancer. This article is part of a Special Issue entitled "The Chornobyl Nuclear Accident: Thirty Years After".

Gamma radiation field intensity meter

DOEpatents

Thacker, L.H.

1995-10-17

A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

Gamma radiation field intensity meter

DOEpatents

Thacker, L.H.

1994-08-16

A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

Possible radioprotective effect of folic acid supplementation on low dose ionizing radiation-induced genomic instability in vitro.

PubMed

Padula, Gisel; Ponzinibbio, María Virginia; Seoane, Analia I

2016-08-01

Ionizing radiation (IR) induces DNA damage through production of single and double-strand breaks and reactive oxygen species (ROS). Folic acid (FA) prevents radiation-induced DNA damage by modification of DNA synthesis and/or repair and as a radical scavenger. We hypothesized that in vitro supplementation with FA will decrease the sensitivity of cells to genetic damage induced by low dose of ionizing radiation. Annexin V, comet and micronucleus assays were performed in cultured CHO cells. After 7 days of pre-treatment with 0, 100, 200 or 300 nM FA, cultures were exposed to radiation (100 mSv). Two un-irradiated controls were executed (0 and 100 nM FA). Data were statistically analyzed with X2-test and linear regression analysis (P 0.05). We observed a significantly decreased frequency of apoptotic cells with the increasing FA concentration (P <0.05). The same trend was observed when analyzing DNA damage and chromosomal instability (P <0.05 for 300 nM). Only micronuclei frequencies showed significant differences for linear regression analysis (R2=94.04; P <0.01). Our results have demonstrated the radioprotective effect of folic acid supplementation on low dose ionizing radiation-induced genomic instability in vitro; folate status should be taken into account when studying the effect of low dose radiation in environmental or occupational exposure.

Protective Effect of Pyruvate Against Radiation-Induced Damage in Collagenized Tissues

NASA Technical Reports Server (NTRS)

Griko, Y. V.; Yan, Xiaoli

2016-01-01

Exposure to high doses of ionizing radiation produces both acute and late effects on the collagenized tissues and have profound effects on wound healing. Because of the crucial practical importance for new radioprotective agents, our study has been focused on evaluation of the efficacy of non-toxic naturally occurring compounds to protect tissue integrity against high-dose gamma radiation. Here, we demonstrate that molecular integrity of collagen may serve as a sensitive biological marker for quantitative evaluation of molecular damage to collagenized tissue and efficacy of radioprotective agents. Increasing doses of gamma radiation (0-50kGy) result in progressive destruction of the native collagen fibrils, which provide a structural framework, strength, and proper milieu for the regenerating tissue. The strategy used in this study involved the thermodynamic specification of all structural changes in collagenized matrix of skin, aortic heart valve, and bone tissue induced by different doses and conditions of g-irradiation. This study describes a simple biophysical approach utilizing the Differential Scanning Calorimetry (DSC) to characterize the structural resistance of the aortic valve matrix exposed to different doses of g-irradiation. It allows us to identify the specific response of each constituent as well as to determine the influence of the different treatments on the characteristic parameters of protein structure. We found that pyruvate, a substance that naturally occurs in the body, provide significant protection (up to 80%) from biochemical and biomechanical damage to the collagenized tissue through the effective targeting of reactive oxygen species. The recently discovered role of pyruvate in the cell antioxidant defense to O2 oxidation, and its essential constituency in the daily human diet, indicate that the administration of pyruvate-based radioprotective formulations may provide safe and effective protection from deleterious effects of ionizing radiation.

Cumulative radiation exposure and cancer risk estimation in children with heart disease.

PubMed

Johnson, Jason N; Hornik, Christoph P; Li, Jennifer S; Benjamin, Daniel K; Yoshizumi, Terry T; Reiman, Robert E; Frush, Donald P; Hill, Kevin D

2014-07-08

Children with heart disease are frequently exposed to imaging examinations that use ionizing radiation. Although radiation exposure is potentially carcinogenic, there are limited data on cumulative exposure and the associated cancer risk. We evaluated the cumulative effective dose of radiation from all radiation examinations to estimate the lifetime attributable risk of cancer in children with heart disease. Children ≤6 years of age who had previously undergone 1 of 7 primary surgical procedures for heart disease at a single institution between 2005 and 2010 were eligible for the study. Exposure to radiation-producing examinations was tabulated, and cumulative effective dose was calculated in millisieverts. These data were used to estimate lifetime attributable risk of cancer above baseline using the approach of the Committee on Biological Effects of Ionizing Radiation VII. The cohort included 337 children exposed to 13 932 radiation examinations. Conventional radiographs represented 92% of examinations, whereas cardiac catheterization and computed tomography accounted for 81% of cumulative exposure. Overall median cumulative effective dose was 2.7 mSv (range, 0.1-76.9 mSv), and the associated lifetime attributable risk of cancer was 0.07% (range, 0.001%-6.5%). Median lifetime attributable risk of cancer ranged widely depending on surgical complexity (0.006%-1.6% for the 7 surgical cohorts) and was twice as high in females per unit exposure (0.04% versus 0.02% per 1-mSv effective dose for females versus males, respectively; P<0.001). Overall radiation exposures in children with heart disease are relatively low; however, select cohorts receive significant exposure. Cancer risk estimation highlights the need to limit radiation dose, particularly for high-exposure modalities. © 2014 American Heart Association, Inc.

Differential miRNA expression profiling reveals miR-205-3p to be a potential radiosensitizer for low- dose ionizing radiation in DLD-1 cells.

PubMed

Andaur, Rodrigo; Tapia, Julio C; Moreno, José; Soto, Leopoldo; Armisen, Ricardo; Marcelain, Katherine

2018-05-29

Enhanced radiosensitivity at low doses of ionizing radiation (IR) (0.2 to 0.6 Gy) has been reported in several cell lines. This phenomenon, known as low doses hyper-radiosensitivity (LDHRS), appears as an opportunity to decrease toxicity of radiotherapy and to enhance the effects of chemotherapy. However, the effect of low single doses IR on cell death is subtle and the mechanism underlying LDHRS has not been clearly explained, limiting the utility of LDHRS for clinical applications. To understand the mechanisms responsible for cell death induced by low-dose IR, LDHRS was evaluated in DLD-1 human colorectal cancer cells and the expression of 80 microRNAs (miRNAs) was assessed by qPCR array. Our results show that DLD-1 cells display an early DNA damage response and apoptotic cell death when exposed to 0.6 Gy. miRNA expression profiling identified 3 over-expressed (miR-205-3p, miR-1 and miR-133b) and 2 down-regulated miRNAs (miR-122-5p, and miR-134-5p) upon exposure to 0.6 Gy. This miRNA profile differed from the one in cells exposed to high-dose IR (12 Gy), supporting a distinct low-dose radiation-induced cell death mechanism. Expression of a mimetic miR-205-3p, the most overexpressed miRNA in cells exposed to 0.6 Gy, induced apoptotic cell death and, more importantly, increased LDHRS in DLD-1 cells. Thus, we propose miR-205-3p as a potential radiosensitizer to low-dose IR.

An Efficient, Affordable Optically Stimulated Luminescent (OSL) Annealer.

PubMed

Abraham, Sara A; Frank, Samuel J; Kearfott, Kimberlee J

2017-07-01

Optically stimulated luminescent (OSL) dosimeters are devices used for measuring doses of ionizing radiation. Signal is stored within an OSL material so that when stimulated with light, light of a specific wavelength is emitted in proportion to the integrated ionizing radiation dose. Each interrogation of the material results in the loss of a small fraction of signal, thus allowing multiple interrogations leading to more accurate measurements of dose. In order to reuse a dosimeter, the residual signals from prior doses must be taken into account and subtracted from current readings, adding uncertainty to any future measurements. To reduce these errors when they become large, it is desirable to completely clear the stored signal or anneal the dosimeter. Traditionally, heating the material has accomplished this. In a commercially available dosimeter badge system, the OSL material Al2O3:C is incorporated into a plastic slide that would melt at the necessary high temperatures, which can reach 900 °C, required for annealing. Fortunately, due to the material's high sensitivity to light, OSLs can be optically annealed instead. In order to do this, an affordable OSL dosimeter annealer was designed with inexpensive, exchangeable blue, green, and white high intensity light-emitting diodes (LEDs). Several dosimeters were repeatedly annealed for recorded intervals and then read out. A single dosimeter was partially annealed through repeated interrogations with the LED array from a commercial reader. The signal loss due to the exposure to each light was analyzed to determine the practicality and efficiency of each color. The rate and extent of signal loss was dependent not only on the spectrum of annealing light but on the initial signal levels as well. These findings suggest that blue LEDs are the most promising for effective and rapid clearing of the OSL material Al2O3:C.

Management of ionizing radiation injuries and illnesses, part 4: acute radiation syndrome.

PubMed

Christensen, Doran M; Iddins, Carol J; Parrillo, Steven J; Glassman, Erik S; Goans, Ronald E

2014-09-01

To provide proper medical care for patients after a radiation incident, it is necessary to make the correct diagnosis in a timely manner and to ascertain the relative magnitude of the incident. The present article addresses the clinical diagnosis and management of high-dose radiation injuries and illnesses in the first 24 to 72 hours after a radiologic or nuclear incident. To evaluate the magnitude of a high-dose incident, it is important for the health physicist, physician, and radiobiologist to work together and to assess many variables, including medical history and physical examination results; the timing of prodromal signs and symptoms (eg, nausea, vomiting, diarrhea, transient incapacitation, hypotension, and other signs and symptoms suggestive of high-level exposure); and the incident history, including system geometry, source-patient distance, and the suspected radiation dose distribution. © 2014 The American Osteopathic Association.

On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy

PubMed Central

Yusof, Fasihah Hanum; Ung, Ngie Min; Wong, Jeannie Hsiu Ding; Jong, Wei Loong; Ath, Vannyat; Phua, Vincent Chee Ee; Heng, Siew Ping; Ng, Kwan Hoong

2015-01-01

This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments. PMID:26052690

Increases in 1H-NMR mobile lipids are not always associated with overt apoptosis: evidence from MG-63 human osteosarcoma three-dimensional spheroids exposed to a low dose (2 Gy) of ionizing radiation.

PubMed

Santini, Maria Teresa; Romano, Rocco; Rainaldi, Gabriella; Ferrante, Antonella; Motta, Andrea; Indovina, Pietro Luigi

2006-02-01

The metabolic changes that occur in MG-63 osteosarcoma three-dimensional tumor spheroids exposed to 2 Gy of ionizing radiation, a dose that is comparable to radiation therapy, were studied using high-resolution proton nuclear magnetic resonance ((1)H-NMR) spectroscopy. Specifically, the (1)H-NMR spectra of control and exposed MG-63 spheroids were compared. Small spheroids (about 50-80 microm in diameter) with no hypoxic center were used. The spectra of whole MG-63 spheroids as well as the perchloric acid extracts of these systems were evaluated. Cell damage was also examined by lactate dehydrogenase release and changes in cell growth. No cell damage was observed, but numerous metabolic changes took place in spheroids after exposure to ionizing radiation. In particular, significant increases in both CH(2) and CH(3) mobile lipids, considered by many authors as markers of apoptosis and also present in MG-63 spheroids undergoing overt apoptosis, were observed in spheroids irradiated with 2 Gy. However, the chromatin dye Hoechst 33258 and DNA fragmentation assays showed no overt apoptosis up to 7 days after irradiation with this low dose. Thus it is evident that increases in mobile lipids do not always indicate actual cell death. A detailed analysis of the other metabolic changes observed appears to suggest that the cell death program was initiated but not completed. In fact, the completely different behavior of two important cellular defense mechanisms, reduced glutathione and taurine, in spheroids irradiated with 2 Gy and in those undergoing overt apoptosis seems to indicate that these systems are protecting spheroids from actual cell death. In addition, these data also suggest that (1)H-NMR can be used to examine the effects of low doses of ionizing radiation in spheroids, a cell model of great complexity that closely resembles tumors in vivo. The importance of this possibility in relation to reaching the ultimate goal of a better evaluation of the outcome of radiotherapy protocols should not be ignored.

Adaptation of the Black Yeast Wangiella dermatitidis to Ionizing Radiation: Molecular and Cellular Mechanisms

PubMed Central

Robertson, Kelly L.; Mostaghim, Anahita; Cuomo, Christina A.; Soto, Carissa M.; Lebedev, Nikolai; Bailey, Robert F.; Wang, Zheng

2012-01-01

Observations of enhanced growth of melanized fungi under low-dose ionizing radiation in the laboratory and in the damaged Chernobyl nuclear reactor suggest they have adapted the ability to survive or even benefit from exposure to ionizing radiation. However, the cellular and molecular mechanism of fungal responses to such radiation remains poorly understood. Using the black yeast Wangiella dermatitidis as a model, we confirmed that ionizing radiation enhanced cell growth by increasing cell division and cell size. Using RNA-seq technology, we compared the transcriptomic profiles of the wild type and the melanin-deficient wdpks1 mutant under irradiation and non-irradiation conditions. It was found that more than 3000 genes were differentially expressed when these two strains were constantly exposed to a low dose of ionizing radiation and that half were regulated at least two fold in either direction. Functional analysis indicated that many genes for amino acid and carbohydrate metabolism and cell cycle progression were down-regulated and that a number of antioxidant genes and genes affecting membrane fluidity were up-regulated in both irradiated strains. However, the expression of ribosomal biogenesis genes was significantly up-regulated in the irradiated wild-type strain but not in the irradiated wdpks1 mutant, implying that melanin might help to contribute radiation energy for protein translation. Furthermore, we demonstrated that long-term exposure to low doses of radiation significantly increased survivability of both the wild-type and the wdpks1 mutant, which was correlated with reduced levels of reactive oxygen species (ROS), increased production of carotenoid and induced expression of genes encoding translesion DNA synthesis. Our results represent the first functional genomic study of how melanized fungal cells respond to low dose ionizing radiation and provide clues for the identification of biological processes, molecular pathways and individual genes regulated by radiation. PMID:23139812

Occupational exposures to antineoplastic drugs and ionizing radiation in Canadian veterinary settings: findings from a national surveillance project.

PubMed

Hall, Amy L; Davies, Hugh W; Demers, Paul A; Nicol, Anne-Marie; Peters, Cheryl E

2013-11-01

Although veterinary workers may encounter various occupational health hazards, a national characterization of exposures is lacking in Canada. This study used secondary data sources to identify veterinary exposure prevalence for ionizing radiation and antineoplastic agents, as part of a national surveillance project. For ionizing radiation, data from the Radiation Protection Bureau of Health Canada were used to identify veterinarians and veterinary technicians monitored in 2006. This was combined with Census statistics to estimate a prevalence range and dose levels. For antineoplastic agents, exposure prevalence was estimated using statistics on employment by practice type and antineoplastic agent usage rates, obtained from veterinary licensing bodies and peer-reviewed literature. In 2006, 7,013 (37% of all) Canadian veterinary workers were monitored for ionizing radiation exposure. An estimated 3.3% to 8.2% of all veterinarians and 2.4% to 7.2% of veterinary technicians were exposed to an annual ionizing radiation dose above 0.1 mSv, representing a total of between 536 and 1,450 workers. All monitored doses were below regulatory limits. For antineoplastic agents, exposure was predicted in up to 5,300 (23%) of all veterinary workers, with an estimated prevalence range of 22% to 24% of veterinarians and 20% to 21% of veterinary technicians. This is the first national-level assessment of exposure to ionizing radiation and antineoplastic agents in Canadian veterinary settings. These hazards may pose considerable health risks. Exposures appeared to be low, however our estimates should be validated with comprehensive exposure monitoring and examination of determinants across practice areas, occupations, and tasks.

Proteomic and Epigenetic Analysis of Rice after Seed Spaceflight and Ground-Base Ion Radiations

NASA Astrophysics Data System (ADS)

Wang, Wei; Sun, Yeqing; Peng, Yuming; Zhao, Qian; Wen, Bin; Yang, Jun

Highly ionizing radiation (HZE) in space is considered as main factor causing biological effects to plant seeds. In previous work, we compared the proteomic profiles of rice plants growing after seed spaceflights to ground controls by two-dimensional difference gel electrophoresis (2-D DIGE) with mass spectrometry and found that the protein expression profiles were changed and differentially expressed proteins participated in most of the biological processes of rice. To further evaluate the dosage effects of space radiation and compare between low- and high-dose ion effects, we carried out three independent ground-base ionizing radiation experiments with different cumulative doses (low-dose range: 2~1000mGy, high-dose range: 2000~20000mGy) to rice seeds and performed proteomic analysis of seedlings. We found that protein expression profiles showed obvious boundaries between low- and high-dose radiation groups. Rates of differentially expressed proteins presented a dose-dependent effect, it reached the highest value at 2000mGy dosage point in all three radiation experiments coincidently; while proteins responded to low-dose radiations preferred to change their expressions at the minimum dosage (2mGy). Proteins participating in rice biological processes also responded differently between low- and high-dose radiations: proteins involved in energy metabolism and photosynthesis tended to be regulated after low-dose radiations while stress responding, protein folding and cell redox homeostasis related proteins preferred to change their expressions after high-dose radiations. By comparing the proteomic profiles between ground-base radiations and spaceflights, it was worth noting that ground-base low-dose ion radiation effects shared similar biological effects as space environment. In addition, we discovered that protein nucleoside diphosphate kinase 1 (NDPK1) showed obvious increased regulation after spaceflights and ion radiations. NDPK1 catalyzes nucleotide metabolism and is reported to be involved in DNA repair process. Its expression sensitivity and specificity were confirmed by RT-PCR and western blot analysis, indicating its potential to be used as space radiation biomarker. Space radiations might induce epigenetic effects on rice plants, especially changes of DNA methylation. Early results suggested that there were correlations between DNA methylation polymorphic and genomic mutation rates. In addition, the 5-methylcytosine located in coding gene’s promoter and exon regions could regulate gene expressions thus influence protein expressions. So whether there is correlation between genome DNA methylation changes and protein expression profile alterations caused by space radiation is worth for further investigation. Therefore we used the same rice samples treated by carbon ion radiation with different doses (0, 10, 20,100, 200, 1000, 2000, 5000, 20000mGy) and applied methylation sensitive amplification polymorphism (MSAP) for scanning genome DNA methylation changes. Interestingly, DNA methylation polymorphism rates also presented a dose-dependent effect and showed the same changing trend as rates of differentially expressed proteins. Whether there are correlations between epigenetic and proteomic effects of space radiation is worth for further investigation.

Optima HD Imax: Molecular Implant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tieger, D. R.; Splinter, P. R.; Hsieh, T. J.

2008-11-03

Molecular implantation offers semiconductor device manufacturers multiple advantages over traditional high current ion implanters. The dose multiplication due to implanting more than one atom per molecule and the transport of beams at higher energies relative to the effective particle energies result in significant throughput enhancements without risk of energy contamination. The Optima HD Imax is introduced with molecular implant capability and the ability to reach up to 4.2 keV effective {sup 11}B from octadecaborane (B{sub 18}H{sub 22}). The ion source and beamline are optimized for molecular species ionization and transport. The beamline is coupled to the Optima HD mechanically scannedmore » endstation. The use of spot beam technology with ionized molecules maximizes the throughput potential and produces uniform implants with fast setup time and with superior angle control. The implanter architecture is designed to run multiple molecular species; for example, in addition to B{sub 18}H{sub 22} the system is capable of implanting carbon molecules for strain engineering and shallow junction engineering. Source lifetime data and typical operating conditions are described both for high dose, memory applications such as dual poly gate as well as lower energy implants for source drain extension and contact implants. Throughputs have been achieved in excess of 50 wafers per hour at doses up to 1x10{sup 16} ions/cm{sup 2} and for energies as low as 1 keV.« less

Heavy Charged Particle Radiobiology: Using Enhanced Biological Effectiveness and Improved Beam Focusing to Advance Cancer Therapy

PubMed Central

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

2011-01-01

Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. PMID:21376738

Radiation effects in Caenorhabditis elegans - Mutagenesis by high and low LET ionizing radiation

NASA Technical Reports Server (NTRS)

Nelson, Gregory A.; Schubert, Wayne W.; Marshall, Tamara M.; Benton, Eric R.; Benton, Eugene V.

1989-01-01

The nematode C. elegans was used to measure the effectiveness of high-energy ionized particles in the induction of three types of genetic lesions. Recessive lethal mutations in a 40-map unit autosomal region, sterility, and X-chromosome nondisjunction or damage were investigated. Induction rates were measured as a function of linear energy transfer, LET(infinity), for nine ions of atomic nunmber 1-57 accelerated at the BEVALAC accelerator. Linear kinetics were observed for all three types of lesions within the dose/fluence ranges tested and were found to vary strongly as a function of particle LET(infinity). Relative biological effectiveness (RBE) values of up to 4.2 were measured, and action cross sections were calculated and compared to mutagenic responses in other systems.

High doses of ionizing radiation on bone repair: is there effect outside the irradiated site?

PubMed

Rocha, Flaviana Soares; Dias, Pâmella Coelho; Limirio, Pedro Henrique Justino Oliveira; Lara, Vitor Carvalho; Batista, Jonas Dantas; Dechichi, Paula

2017-03-01

Local ionizing radiation causes damage to bone metabolism, it reduces blood supply and cellularity over time. Recent studies indicate that radiation promotes biological response outside the treatment field. The aim of this study was to investigate the effects of ionizing radiation on bone repair outside the irradiated field. Ten healthy male Wistar rats were used; and five animals were submitted to radiotherapy on the left femur. After 4 weeks, in all animals were created bone defects in the right and left femurs. Seven days after surgery, animals were euthanized. The femurs were removed and randomly divided into 3 groups (n=5): Control (C) (right femur of the non-irradiated animals); Local ionizing radiation (IR) (left femur of the irradiated animals); Contralateral ionizing radiation (CIR) (right femur of the irradiated animals). The femurs were processed and embedded in paraffin; and bone histologic sections were evaluated to quantify the bone neoformation. Histomorphometric analysis showed that there was no significant difference between groups C (24.6±7.04) and CIR (25.3±4.31); and IR group not showed bone neoformation. The results suggest that ionizing radiation affects bone repair, but does not interfere in bone repair distant from the primary irradiated site. Copyright © 2016 Elsevier Ltd. All rights reserved.

Time-resolved dosimetry using a pinpoint ionization chamber as quality assurance for IMRT and VMAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louwe, Robert J. W., E-mail: rob.louwe@ccdbh.org.nz; Satherley, Thomas; Day, Rebecca A.

Purpose: To develop a method to verify the dose delivery in relation to the individual control points of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) using an ionization chamber. In addition to more effective problem solving during patient-specific quality assurance (QA), the aim is to eventually map out the limitations in the treatment chain and enable a targeted improvement of the treatment technique in an efficient way. Methods: Pretreatment verification was carried out for 255 treatment plans that included a broad range of treatment indications in two departments using the equipment of different vendors. In-house developed softwaremore » was used to enable calculation of the dose delivery for the individual beamlets in the treatment planning system (TPS), for data acquisition, and for analysis of the data. The observed deviations were related to various delivery and measurement parameters such as gantry angle, field size, and the position of the detector with respect to the field edge to distinguish between error sources. Results: The average deviation of the integral fraction dose during pretreatment verification of the planning target volume dose was −2.1% ± 2.2% (1 SD), −1.7% ± 1.7% (1 SD), and 0.0% ± 1.3% (1 SD) for IMRT at the Radboud University Medical Center (RUMC), VMAT (RUMC), and VMAT at the Wellington Blood and Cancer Centre, respectively. Verification of the dose to organs at risk gave very similar results but was generally subject to a larger measurement uncertainty due to the position of the detector at a high dose gradient. The observed deviations could be related to limitations of the TPS beam models, attenuation of the treatment couch, as well as measurement errors. The apparent systematic error of about −2% in the average deviation of the integral fraction dose in the RUMC results could be explained by the limitations of the TPS beam model in the calculation of the beam penumbra. Conclusions: This study showed that time-resolved dosimetry using an ionization chamber is feasible and can be largely automated which limits the required additional time compared to integrated dose measurements. It provides a unique QA method which enables identification and quantification of the contribution of various error sources during IMRT and VMAT delivery.« less

Cooperative biological effects between ionizing radiation and other physical and chemical agents.

PubMed

Manti, Lorenzo; D'Arco, Annalisa

2010-01-01

Exposure to ionizing radiation (IR), at environmentally and therapeutically relevant doses or as a result of diagnostics or accidents, causes cyto- and genotoxic damage. However, exposure to IR alone is a rare event as it occurs in spatial and temporal combination with several physico-chemical agents. Some of these are of known noxiousness, as is the case with chemical compounds at high dose, hence additive/synergistic effects can be expected or have been demonstrated. Conversely, the cellular toxicity of other agents, such as non-ionizing electromagnetic fields (EMFs), is only presumed and their short- and long-term cooperation on IR-induced damage remains undetermined. In this review, we shall examine evidence in support of the interplay between spatially and/or temporally related environmentally relevant stressors. In vitro or animal-based studies as well as epidemiological surveys have generally examined the combined action of no more than a couple of known or potentially DNA-damaging agents. Moreover, most existing research mainly focused on short-term effects of combined exposures. Hence, it is important that quantitative research addresses the issue of the possible cooperation between chronic exposure to environmental trace contaminants and exposure to EMFs, examining not only the modulation of damage acutely induced by IR but also long-term genome stability. 2010 Elsevier B.V. All rights reserved.

Genetic background modulates lncRNA-coordinated tissue response to low dose ionizing radiation

DOE PAGES

Tang, Jonathan; Huang, Yurong; Nguyen, David H.; ...

2015-02-04

Long noncoding RNAs (lncRNAs) are emerging as key regulators of diverse cell functions and processes. However, the relevance of lncRNAs in the cell and tissue response to ionizing radiation has not yet been characterized. Here we used microarray profiling to determine lncRNA and mRNA expression in mammary glands of BALB/c and SPRET/EiJ mice after low-dose ionizing radiation (LDIR) exposure. We found that unirradiated mammary tissues of these strains differed significantly in baseline expressions of 290 lncRNAs. LDIR exposure (10 cGy) induced a significant change in the expression of many lncRNAs. The vast majority of lncRNAs identified to be differentially expressed aftermore » LDIR in either BALB/c or SPRET/EiJ had a significantly correlated expression pattern with at least one LDIR responsive mRNA. Functional analysis revealed that the response to LDIR in BALB/c mice is highly dynamic with enrichment for genes involved in tissue injury, inflammatory responses, and mammary gland development at 2, 4, and 8 weeks after LDIR, respectively. Our study demonstrates that genetic background strongly influences the expression of lncRNAs and their response to radiation and that lncRNAs may coordinate the tissue response to LDIR exposure via regulation of coding mRNAs.« less

Genetic background modulates lncRNA-coordinated tissue response to low dose ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Jonathan; Huang, Yurong; Nguyen, David H.

Long noncoding RNAs (lncRNAs) are emerging as key regulators of diverse cell functions and processes. However, the relevance of lncRNAs in the cell and tissue response to ionizing radiation has not yet been characterized. Here we used microarray profiling to determine lncRNA and mRNA expression in mammary glands of BALB/c and SPRET/EiJ mice after low-dose ionizing radiation (LDIR) exposure. We found that unirradiated mammary tissues of these strains differed significantly in baseline expressions of 290 lncRNAs. LDIR exposure (10 cGy) induced a significant change in the expression of many lncRNAs. The vast majority of lncRNAs identified to be differentially expressed aftermore » LDIR in either BALB/c or SPRET/EiJ had a significantly correlated expression pattern with at least one LDIR responsive mRNA. Functional analysis revealed that the response to LDIR in BALB/c mice is highly dynamic with enrichment for genes involved in tissue injury, inflammatory responses, and mammary gland development at 2, 4, and 8 weeks after LDIR, respectively. Our study demonstrates that genetic background strongly influences the expression of lncRNAs and their response to radiation and that lncRNAs may coordinate the tissue response to LDIR exposure via regulation of coding mRNAs.« less

The Effects of Low Dose-Rate Ionizing Radiation on the Shapes of Transients in the LM124 Operational Amplifier

NASA Technical Reports Server (NTRS)

Buchner, Stephen; McMorrow, Dale; Roche, Nicholas; Dusseau, Laurent; Pease, Ron L.

2008-01-01

Shapes of single event transients (SETs) in a linear bipolar circuit (LM124) change with exposure to total ionizing dose (TID) radiation. SETs shape changes are a direct consequence of TID-induced degradation of bipolar transistor gain. A reduction in transistor gain causes a reduction in the drive current of the current sources in the circuit, and it is the lower drive current that most affects the shapes of large amplitude SETs.

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

NASA Astrophysics Data System (ADS)

Ioan, M.-R.

2016-06-01

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

Evaluation of the dosimetric properties of a diode detector for small field proton radiosurgery

PubMed Central

Teran, Anthony V.; Slater, Jerry D.; Slater, James M.; Wroe, Andrew J.

2015-01-01

The small fields and sharp gradients typically encountered in proton radiosurgery require high spatial resolution dosimetric measurements, especially below 1–2 cm diameters. Radiochromic film provides high resolution, but requires postprocessing and special handling. Promising alternatives are diode detectors with small sensitive volumes (SV) that are capable of high resolution and real‐time dose acquisition. In this study we evaluated the PTW PR60020 proton dosimetry diode using radiation fields and beam energies relevant to radiosurgery applications. Energies of 127 and 157 MeV (9.7 to 15 cm range) and initial diameters of 8, 10, 12, and 20 mm were delivered using single‐stage scattering and four modulations (0, 15, 30, and 60 mm) to a water tank in our treatment room. Depth dose and beam profile data were compared with PTW Markus N23343 ionization chamber, EBT2 Gafchromic film, and Monte Carlo simulations. Transverse dose profiles were measured using the diode in "edge‐on" orientation or EBT2 film. Diode response was linear with respect to dose, uniform with dose rate, and showed an orientation‐dependent (i.e., beam parallel to, or perpendicular to, detector axis) response of less than 1%. Diode vs. Markus depth‐dose profiles, as well as Markus relative dose ratio vs. simulated dose‐weighted average lineal energy plots, suggest that any LET‐dependent diode response is negligible from particle entrance up to the very distal portion of the SOBP for the energies tested. Finally, while not possible with the ionization chamber due to partial volume effects, accurate diode depth‐dose measurements of 8, 10, and 12 mm diameter beams were obtained compared to Monte Carlo simulations. Because of the small SV that allows measurements without partial volume effects and the capability of submillimeter resolution (in edge‐on orientation) that is crucial for small fields and high‐dose gradients (e.g., penumbra, distal edge), as well as negligible LET dependence over nearly the full the SOBP, the PTW proton diode proved to be a useful high‐resolution, real‐time metrology device for small proton field radiation measurements such as would be encountered in radiosurgery applications. PACS numbers: 87.56.‐v, 87.56.jf, 87.56.Fc PMID:26699554

Space charge dosimeters for extremely low power measurements of radiation in shipping containers

DOEpatents

Britton, Jr., Charles L.; Buckner, Mark A [Oak Ridge, TN; Hanson, Gregory R [Clinton, TN; Bryan, William L [Knoxville, TN

2011-05-03

Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

Space charge dosimeters for extremely low power measurements of radiation in shipping containers

DOEpatents

Britton, Jr; Charles, L [Alcoa, TN; Buckner, Mark A [Oak Ridge, TN; Hanson, Gregory R [Clinton, TN; Bryan, William L [Knoxville, TN

2011-04-26

Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes in situ polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

Background Ionizing Radiation and the Risk of Childhood Cancer: A Census-Based Nationwide Cohort Study

PubMed Central

Lupatsch, Judith E.; Zwahlen, Marcel; Röösli, Martin; Niggli, Felix; Grotzer, Michael A.; Rischewski, Johannes; Egger, Matthias; Kuehni, Claudia E.

2015-01-01

Background Exposure to medium or high doses of ionizing radiation is a known risk factor for cancer in children. The extent to which low-dose radiation from natural sources contributes to the risk of childhood cancer remains unclear. Objectives In a nationwide census-based cohort study, we investigated whether the incidence of childhood cancer was associated with background radiation from terrestrial gamma and cosmic rays. Methods Children < 16 years of age in the Swiss National Censuses in 1990 and 2000 were included. The follow-up period lasted until 2008, and incident cancer cases were identified from the Swiss Childhood Cancer Registry. A radiation model was used to predict dose rates from terrestrial and cosmic radiation at locations of residence. Cox regression models were used to assess associations between cancer risk and dose rates and cumulative dose since birth. Results Among 2,093,660 children included at census, 1,782 incident cases of cancer were identified including 530 with leukemia, 328 with lymphoma, and 423 with a tumor of the central nervous system (CNS). Hazard ratios for each millisievert increase in cumulative dose of external radiation were 1.03 (95% CI: 1.01, 1.05) for any cancer, 1.04 (95% CI: 1.00, 1.08) for leukemia, 1.01 (95% CI: 0.96, 1.05) for lymphoma, and 1.04 (95% CI: 1.00, 1.08) for CNS tumors. Adjustment for a range of potential confounders had little effect on the results. Conclusions Our study suggests that background radiation may contribute to the risk of cancer in children, including leukemia and CNS tumors. Citation Spycher BD, Lupatsch JE, Zwahlen M, Röösli M, Niggli F, Grotzer MA, Rischewski J, Egger M, Kuehni CE, for the Swiss Pediatric Oncology Group and the Swiss National Cohort. 2015. Background ionizing radiation and the risk of childhood cancer: a census-based nationwide cohort study. Environ Health Perspect 123:622–628; http://dx.doi.org/10.1289/ehp.1408548 PMID:25707026

Fundamentals of Radiation Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bos, Adrie J. J.

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 measuringmore » the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.« less

Total Dose Effects on Single Event Transients in Digital CMOS and Linear Bipolar Circuits

NASA Technical Reports Server (NTRS)

Buchner, S.; McMorrow, D.; Sibley, M.; Eaton, P.; Mavis, D.; Dusseau, L.; Roche, N. J-H.; Bernard, M.

2009-01-01

This presentation discusses the effects of ionizing radiation on single event transients (SETs) in circuits. The exposure of integrated circuits to ionizing radiation changes electrical parameters. The total ionizing dose effect is observed in both complementary metal-oxide-semiconductor (CMOS) and bipolar circuits. In bipolar circuits, transistors exhibit grain degradation, while in CMOS circuits, transistors exhibit threshold voltage shifts. Changes in electrical parameters can cause changes in single event upset(SEU)/SET rates. Depending on the effect, the rates may increase or decrease. Therefore, measures taken for SEU/SET mitigation might work at the beginning of a mission but not at the end following TID exposure. The effect of TID on SET rates should be considered if SETs cannot be tolerated.

Development and evaluation of polycrystalline cadmium telluride dosimeters for accurate quality assurance in radiation therapy

NASA Astrophysics Data System (ADS)

Oh, K.; Han, M.; Kim, K.; Heo, Y.; Moon, C.; Park, S.; Nam, S.

2016-02-01

For quality assurance in radiation therapy, several types of dosimeters are used such as ionization chambers, radiographic films, thermo-luminescent dosimeter (TLD), and semiconductor dosimeters. Among them, semiconductor dosimeters are particularly useful for in vivo dosimeters or high dose gradient area such as the penumbra region because they are more sensitive and smaller in size compared to typical dosimeters. In this study, we developed and evaluated Cadmium Telluride (CdTe) dosimeters, one of the most promising semiconductor dosimeters due to their high quantum efficiency and charge collection efficiency. Such CdTe dosimeters include single crystal form and polycrystalline form depending upon the fabrication process. Both types of CdTe dosimeters are commercially available, but only the polycrystalline form is suitable for radiation dosimeters, since it is less affected by volumetric effect and energy dependence. To develop and evaluate polycrystalline CdTe dosimeters, polycrystalline CdTe films were prepared by thermal evaporation. After that, CdTeO3 layer, thin oxide layer, was deposited on top of the CdTe film by RF sputtering to improve charge carrier transport properties and to reduce leakage current. Also, the CdTeO3 layer which acts as a passivation layer help the dosimeter to reduce their sensitivity changes with repeated use due to radiation damage. Finally, the top and bottom electrodes, In/Ti and Pt, were used to have Schottky contact. Subsequently, the electrical properties under high energy photon beams from linear accelerator (LINAC), such as response coincidence, dose linearity, dose rate dependence, reproducibility, and percentage depth dose, were measured to evaluate polycrystalline CdTe dosimeters. In addition, we compared the experimental data of the dosimeter fabricated in this study with those of the silicon diode dosimeter and Thimble ionization chamber which widely used in routine dosimetry system and dose measurements for radiation therapy.

A comparison of simple and realistic eye models for calculation of fluence to dose conversion coefficients in a broad parallel beam incident of protons

NASA Astrophysics Data System (ADS)

Sakhaee, Mahmoud; Vejdani-Noghreiyan, Alireza; Ebrahimi-Khankook, Atiyeh

2015-01-01

Radiation induced cataract has been demonstrated among people who are exposed to ionizing radiation. To evaluate the deterministic effects of ionizing radiation on the eye lens, several papers dealing with the eye lens dose have been published. ICRP Publication 103 states that the lens of the eye may be more radiosensitive than previously considered. Detailed investigation of the response of the lens showed that there are strong differences in sensitivity to ionizing radiation exposure with respect to cataract induction among the tissues of the lens of the eye. This motivated several groups to look deeper into issue of the dose to a sensitive cell population within the lens, especially for radiations with low energy penetrability that have steep dose gradients inside the lens. Two sophisticated mathematical models of the eye including the inner structure have been designed for the accurate dose estimation in recent years. This study focuses on the calculations of the absorbed doses of different parts of the eye using the stylized models located in UF-ORNL phantom and comparison with the data calculated with the reference computational phantom in a broad parallel beam incident of protons with energies between 20 MeV and 10 GeV. The obtained results indicate that the total lens absorbed doses of reference phantom has good compliance with those of the more sensitive regions of stylized models. However, total eye absorbed dose of these models greatly differ with each other for lower energies.

Effect of Photon Hormesis on Dose Responses to Alpha Particles in Zebrafish Embryos.

PubMed

Ng, Candy Yuen Ping; Cheng, Shuk Han; Yu, Kwan Ngok

2017-02-11

Photon hormesis refers to the phenomenon where the biological effect of ionizing radiation with a high linear energy transfer (LET) value is diminished by photons with a low LET value. The present paper studied the effect of photon hormesis from X-rays on dose responses to alpha particles using embryos of the zebrafish ( Danio rerio ) as the in vivo vertebrate model. The toxicity of these ionizing radiations in the zebrafish embryos was assessed using the apoptotic counts at 20, 24, or 30 h post fertilization (hpf) revealed through acridine orange (AO) staining. For alpha-particle doses ≥ 4.4 mGy, the additional X-ray dose of 10 mGy significantly reduced the number of apoptotic cells at 24 hpf, which proved the presence of photon hormesis. Smaller alpha-particle doses might not have inflicted sufficient aggregate damages to trigger photon hormesis. The time gap T between the X-ray (10 mGy) and alpha-particle (4.4 mGy) exposures was also studied. Photon hormesis was present when T ≤ 30 min, but was absent when T = 60 min, at which time repair of damage induced by alpha particles would have completed to prevent their interactions with those induced by X-rays. Finally, the drop in the apoptotic counts at 24 hpf due to photon hormesis was explained by bringing the apoptotic events earlier to 20 hpf, which strongly supported the removal of aberrant cells through apoptosis as an underlying mechanism for photon hormesis.

RESPONSE OF THE GREEK EARLY WARNING SYSTEM REUTER-STOKES IONIZATION CHAMBERS TO TERRESTRIAL AND COSMIC RADIATION EVALUATED IN COMPARISON WITH SPECTROSCOPIC DATA AND TIME SERIES ANALYSIS.

PubMed

Leontaris, F; Clouvas, A; Xanthos, S; Maltezos, A; Potiriadis, C; Kiriakopoulos, E; Guilhot, J

2018-02-01

The Telemetric Early Warning System Network of the Greek Atomic Energy Commission consists mainly of a network of 24 Reuter-Stokes high-pressure ionization chambers (HPIC) for gamma dose rate measurements and covers all Greece. In the present work, the response of the Reuter-Stokes HPIC to terrestrial and cosmic radiation was evaluated in comparison with spectroscopic data obtained by in situ gamma spectrometry measurements with portable hyper pure Germanium detectors (HPGe), near the Reuter-Stokes detectors and time series analysis. For the HPIC detectors, a conversion factor for the measured absorbed dose rate in air (in nGy h-1) to the total ambient dose equivalent rate Ḣ*(10), due to terrestrial and cosmic component, was deduced by the field measurements. Time series analysis of the mean monthly dose rate (measured by the Reuter-Stokes detector in Thessaloniki, northern Greece, from 2001 to 2016) was performed with advanced statistical methods (Fast Fourier Analysis and Zhao Atlas Marks Transform). Fourier analysis reveals several periodicities (periodogram). The periodogram of the absorbed dose rate in air values was compared with the periodogram of the values measured for the same period (2001-16) and in the same location with a NaI (Tl) detector which in principle is not sensitive to cosmic radiation. The obtained results are presented and discussed. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Investigation of the chamber correction factor (k(ch)) for the UK secondary standard ionization chamber (NE2561/NE2611) using medium-energy x-rays.

PubMed

Rosser, K E

1998-11-01

This paper evaluates the characteristics of ionization chambers for the measurement of absorbed dose to water for medium-energy x-rays. The values of the chamber correction factor, k(ch), used in the IPEMB code of practice for the UK secondary standard (NE2561/NE2611) ionization chamber are derived and their constituent factors examined. The comparison of the chambers' responses in air revealed that of the chambers tested only the NE2561, NE2571 and NE2505 exhibit a flat (within 5%) energy response in air. Under no circumstances should the NACP, Sanders electron chamber, or any chamber that has a wall made of high atomic number material, be used for medium-energy x-ray dosimetry. The measurements in water reveal that a chamber that has a substantial housing, such as the PTW Grenz chamber, should not be used to measure absorbed dose to water in this energy range. The value of k(ch) for an NE2561 chamber was determined by measuring the absorbed dose to water and comparing it with that for an NE2571 chamber, for which k(ch) data have been published. The chamber correction factor varies from 1.023 +/- 0.03 to 1.018 +/- 0.001 for x-ray beams with HVL between 0.15 and 4 mm Cu. The values agree with that for an NE2571 chamber within the experimental uncertainty. The corrections due to the stem, waterproof sleeve and replacement of the phantom material by the chamber for an NE2561 chamber are described.

Monte Carlo studies on photon interactions in radiobiological experiments

PubMed Central

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

2018-01-01

X-ray and γ-ray photons have been widely used for studying radiobiological effects of ionizing radiations. Photons are indirectly ionizing radiations so they need to set in motion electrons (which are a directly ionizing radiation) to perform the ionizations. When the photon dose decreases to below a certain limit, the number of electrons set in motion will become so small that not all cells in an “exposed” cell population can get at least one electron hit. When some cells in a cell population are not hit by a directly ionizing radiation (in other words not irradiated), there will be rescue effect between the irradiated cells and non-irradiated cells, and the resultant radiobiological effect observed for the “exposed” cell population will be different. In the present paper, the mechanisms underlying photon interactions in radiobiological experiments were studied using our developed NRUphoton computer code, which was benchmarked against the MCNP5 code by comparing the photon dose delivered to the cell layer underneath the water medium. The following conclusions were reached: (1) The interaction fractions decreased in the following order: 16O > 12C > 14N > 1H. Bulges in the interaction fractions (versus water medium thickness) were observed, which reflected changes in the energies of the propagating photons due to traversals of different amount of water medium as well as changes in the energy-dependent photon interaction cross-sections. (2) Photoelectric interaction and incoherent scattering dominated for lower-energy (10 keV) and high-energy (100 keV and 1 MeV) incident photons. (3) The fractions of electron ejection from different nuclei were mainly governed by the photoelectric effect cross-sections, and the fractions from the 1s subshell were the largest. (4) The penetration fractions in general decreased with increasing medium thickness, and increased with increasing incident photon energy, the latter being explained by the corresponding reduction in interaction cross-sections. (5) The areas under the angular distribution curves of photons exiting the medium layer and subsequently undergoing interactions within the cell layer became smaller for larger incident photon energies. (6) The number of cells suffering at least one electron hit increased with the administered dose. For larger incident photon energies, the numbers of cells suffering at least one electron hit became smaller, which was attributed to the reduction in the photon interaction cross-section. These results highlighted the importance of the administered dose in radiobiological experiments. In particular, the threshold administered doses at which all cells in the exposed cell array suffered at least one electron hit might provide hints on explaining the intriguing observation that radiation-induced cancers can be statistically detected only above the threshold value of ~100 mSv, and thus on reconciling controversies over the linear no-threshold model. PMID:29561871

Low-dose radiation: a cause of breast cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Land, C.E.

1980-08-15

It is likely that the breast is the organ most sensitive to radiation carcinogenesis in postpubertal women. Studies of different exposed populations have yielded remarkably consistent results, in spite of wide differences in underlying breast cancer rates and conditions of exposure. Excess risk is approximately proportional to dose, and is relatively independent of ionization density and fractionization of dose. This implies that the risk associated with low-dose exposures to ionizing radiation can be estimated with some confidence from higher-dose data. Excess risk is heavily dependent on age at exposure but relatively independent of population differences in normal risk. The temporalmore » patterns after exposure of both radiation-induced and naturally occurring breast cancer are similar, suggesting a strong influence of factors other than radiation on radiation-induced breast cancer. Uncertainties remain about risks from exposures before puberty and after menopause.« less

Effects of Ionizing Radiation on the Heart

PubMed Central

Boerma, Marjan; Sridharan, Vijayalakshmi; Mao, Xiao-Wen; Nelson, Gregory A.; Cheema, Amrita K.; Koturbash, Igor; Singh, Sharda P.; Tackett, Alan J.; Hauer-Jensen, Martin

2016-01-01

This article provides an overview of studies addressing effects of ionizing radiation on the heart. Clinical studies have identified early and late manifestations of radiation-induced heart disease, a side effect of radiation therapy to tumors in the chest when all or part of the heart is situated in the radiation field. Studies in preclinical animal models have contributed to our understanding of the mechanisms by which radiation may injure the heart. More recent observations in human subjects suggest that ionizing radiation may have cardiovascular effects at lower doses than was previously thought. This has led to examinations of low-dose photons and low-dose charged particle irradiation in animal models. Lastly, studies have started to identify noninvasive methods for detection of cardiac radiation injury and interventions that may prevent or mitigate these adverse effects. Altogether, this ongoing research should increase our knowledge of biological mechanisms of cardiovascular radiation injury, identify non-invasive biomarkers for early detection, and potential interventions that may prevent or mitigate these adverse effects. PMID:27919338

Irradiation treatment of pharmaceutical and personal care products (PPCPs) in water and wastewater: An overview

NASA Astrophysics Data System (ADS)

Wang, Jianlong; Chu, Libing

2016-08-01

Pharmaceutical and personal care products (PPCPs), especially the pharmaceutically active compounds (PhACs) such as antibiotics and hormones have attracted great concerns worldwide for their persistence and potential threat to ecosystem and public health. This paper presents an overview on the ionizing irradiation-induced degradation of PPCPs in aqueous solution. Parameters that affect PPCPs degradation, such as the absorbed dose, solution pH, dose rate, water matrices and the presence of some inorganic ions and humic acid are evaluated. The mechanism and pathways of radiolytic degradation of PPCPs are reviewed. In many cases, PPCPs such as antibiotics and X-ray contrast agent could be removed completely by radiation, but a higher absorbed dose was needed for their mineralization and toxicity reduction. The combination of ionizing irradiation with other methods such as H2O2, ozonation and TiO2 nanoparticles could improve the degradation efficacy and reduce the cost. Ionizing irradiation is a promising alternative for degradation of PPCPs in aqueous solution.

Damage pattern as a function of radiation quality and other factors.

PubMed

Burkart, W; Jung, T; Frasch, G

1999-01-01

An understanding of damage pattern in critical cellular structures such as DNA is an important prerequisite for a mechanistic assessment of primary radiation damage, its possible repair, and the propagation of residual changes in somatic and germ cells as potential contributors to disease or ageing. Important quantitative insights have been made recently on the distribution in time and space of critical lesions from direct and indirect action of ionizing radiation on mammalian cells. When compared to damage from chemicals or from spontaneous degradation, e.g. depurination or base deamination in DNA, the potential of even low-LET radiation to create local hot spots of damage from single particle tracks is of utmost importance. This has important repercussions on inferences from critical biological effects at high dose and dose rate exposure situations to health risks at chronic, low-level exposures as experienced in environmental and controlled occupational settings. About 10,000 DNA lesions per human cell nucleus and day from spontaneous degradation and chemical attack cause no apparent effect, but a dose of 4 Gy translating into a similar number of direct and indirect DNA breaks induces acute lethality. Therefore, single lesions cannot explain the high efficiency of ionizing radiation in the induction of mutation, transformation and loss of proliferative capacity. Clustered damage leading to poorly repairable double-strand breaks or even more complex local DNA degradation, correlates better with fixed damage and critical biological endpoints. A comparison with other physical, chemical and biological agents indicates that ionizing radiation is indeed set apart from these by its unique micro- and nano-dosimetric traits. Only a few other agents such as bleomycin have a similar potential to cause complex damage from single events. However, in view of the multi-stage mechanism of carcinogenesis, it is still an open question whether dose-effect linearity for complex primary DNA damage and resulting fixed critical cellular lesions translate into linearity for radiation-induced cancer. To solve this enigma, a quantitative assessment of all genotoxic and harmful non-genotoxic agents affecting the human body would be needed.

Effective radiation exposure evaluation during a one year follow-up of urolithiasis patients after extracorporeal shock wave lithotripsy

PubMed Central

Tekinarslan, Erdem; Keskin, Suat; Buldu, İbrahim; Sönmez, Mehmet Giray; Karatag, Tuna; Istanbulluoglu, Mustafa Okan

2015-01-01

Introduction To determine and evaluate the effective radiation exposure during a one year follow-up of urolithiasis patients following the SWL (extracorporeal shock wave lithotripsy) treatment. Material and methods Total Effective Radiation Exposure (ERE) doses for each of the 129 patients: 44 kidney stone patients, 41 ureter stone patients, and 44 multiple stone location patients were calculated by adding up the radiation doses of each ionizing radiation session including images (IVU, KUB, CT) throughout a one year follow-up period following the SWL. Results Total mean ERE values for the kidney stone group was calculated as 15, 91 mSv (5.10-27.60), for the ureter group as 13.32 mSv (5.10-24.70), and in the multiple stone location group as 27.02 mSv (9.41-54.85). There was no statistically significant differences between the kidney and ureter groups in terms of the ERE dose values (p = 0.221) (p >0.05). In the comparison of the kidney and ureter stone groups with the multiple stone location group; however, there was a statistically significant difference (p = 0.000) (p <0.05). Conclusions ERE doses should be a factor to be considered right at the initiation of any diagnostic and/or therapeutic procedure. Especially in the case of multiple stone locations, due to the high exposure to ionized radiation, different imaging modalities with low dose and/or totally without a dose should be employed in the diagnosis, treatment, and follow-up bearing the aim to optimize diagnosis while minimizing the radiation dose as much as possible. PMID:26568880

Intensity- and energy-modulated electron radiotherapy by means of an xMLC for head and neck shallow tumors

NASA Astrophysics Data System (ADS)

Salguero, Francisco Javier; Arráns, Rafael; Atriana Palma, Bianey; Leal, Antonio

2010-03-01

The purpose of this paper is to assess the feasibility of delivering intensity- and energy-modulated electron radiation treatment (MERT) by a photon multileaf collimator (xMLC) and to evaluate the improvements obtained in shallow head and neck (HN) tumors. Four HN patient cases covering different clinical situations were planned by MERT, which used an in-house treatment planning system that utilized Monte Carlo dose calculation. The cases included one oronasal, two parotid and one middle ear tumors. The resulting dose-volume histograms were compared with those obtained from conventional photon and electron treatment techniques in our clinic, which included IMRT, electron beam and mixed beams, most of them using fixed-thickness bolus. Experimental verification was performed with plane-parallel ionization chambers for absolute dose verification, and a PTW ionization chamber array and radiochromic film for relative dosimetry. A MC-based treatment planning system for target with compromised volumes in depth and laterally has been validated. A quality assurance protocol for individual MERT plans was launched. Relative MC dose distributions showed a high agreement with film measurements and absolute ion chamber dose measurements performed at a reference point agreed with MC calculations within 2% in all cases. Clinically acceptable PTV coverage and organ-at-risk sparing were achieved by using the proposed MERT approach. MERT treatment plans, based on delivery of intensity-modulated electron beam using the xMLC, for superficial head and neck tumors, demonstrated comparable or improved PTV dose homogeneity with significantly lower dose to normal tissues. The clinical implementation of this technique will be able to offer a viable alternative for the treatment of shallow head and neck tumors.

The Nuclear Weapons Effects National Enterprise

DTIC Science & Technology

2010-06-01

dependent on computers and electrical circuitry for effectiveness. The danger from radiation induced upset or burnout of improperly or unshielded...for Unmanned Systems Radiation Effect Thermal mechanical shock - X-ray Prompt X-ray/gamma dose rate - Rail-span collapse - Photoionization burnout ...event upset (SEU) or even single-event burnout . SEU results when enough ionization charge is deposited by a high-energy particle (natural or man

Mechanisms of cell killing by the new anti-cancer drug SR 4233

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J.

SR 4233 (3-amino-1,2,4-benzotriazine, 1,4-dioxide) is a new potential anti-cancer drug which has a highly selective toxicity to hypoxic cells. This study investigated the mechanism of cell killing by this drug. Enzymatic studies have shown that SR 4233 is reductively metabolized to SR 4317 by the tumor cell lines SCVII and HT 1080 under hypoxic conditions. Cytochrome P-450 may play a major role in the reduction in both cell lines. DT diaphorase is the second most important enzyme in reducing SR 4233. In characterizing the major cellular target for SR 4233, the author has shown that damage to cell mitochondria ismore » produced largely under aerobic conditions, whereas DNA is likely to be the major target for cell death under hypoxic conditions. Further experiments demonstrated that DNA damage was similar to that produced by ionizing radiation at equitoxic doses, and chromosome aberrations can entirely account for cell death by SR 4233 under hypoxic conditions in the low dose range. Nevertheless, chromosome breaks produced by SR 4233 are less repairable than those produced by ionizing radiation, suggesting highly localized damage in the DNA by discrete foci of SR 4233 radicals.« less

Radiation-induced immune responses: mechanisms and therapeutic perspectives.

PubMed

Jeong, Hoibin; Bok, Seoyeon; Hong, Beom-Ju; Choi, Hyung-Seok; Ahn, G-One

2016-09-01

Recent advancement in the radiotherapy technology has allowed conformal delivery of high doses of ionizing radiation precisely to the tumors while sparing large volume of the normal tissues, which have led to better clinical responses. Despite this technological advancement many advanced tumors often recur and they do so within the previously irradiated regions. How could tumors recur after receiving such high ablative doses of radiation? In this review, we outlined how radiation can elicit anti-tumor responses by introducing some of the cytokines that can be induced by ionizing radiation. We then discuss how tumor hypoxia, a major limiting factor responsible for failure of radiotherapy, may also negatively impact the anti-tumor responses. In addition, we highlight how there may be other populations of immune cells including regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs) that can be recruited to tumors interfering with the anti-tumor immunity. Finally, the impact of irradiation on tumor hypoxia and the immune responses according to different radiotherapy regimen is also delineated. It is indeed an exciting time to see that radiotherapy is being combined with immunotherapy in the clinic and we hope that this review can add an excitement to the field.

Long-term biological effects induced by ionizing radiation--implications for dose mediated risk.

PubMed

Miron, S D; Astărăstoae, V

2014-01-01

Ionizing radiations are considered to be risk agents that are responsible for the effects on interaction with living matter. The occurring biological effects are due to various factors such as: dose, type of radiation, exposure time, type of biological tissue, health condition and the age of the person exposed. The mechanisms involved in the direct modifications of nuclear DNA and mitochondrial DNA are reviewed. Classical target theory of energy deposition in the nucleus that causes DNA damages, in particular DNA double-strand breaks and that explanation of the biological consequences of ionizing radiation exposure is a paradigm in radiobiology. Recent experimental evidences have demonstrated the existence of a molecular mechanism that explains the non-targeted effects of ionizing radiation exposure. Among these novel data, genomic instability and a variety of bystander effects are discussed here. Those bystander effects of ionizing radiation are fulfilled by cellular communication systems that give rise to non-targeted effects in the neighboring non irradiated cells. This paper provides also a commentary on the synergistic effects induced by the co-exposures to ionizing radiation and various physical agents such as electromagnetic fields and the co-exposures to ionizing radiation and chemical environmental contaminants such as metals. The biological effects of multiple stressors on genomic instability and bystander effects are also discussed. Moreover, a brief presentation of the methods used to characterize cyto- and genotoxic damages is offered.

Effects of low-dose ionizing radiation and menadione, an inducer of oxidative stress, alone and in combination in a vertebrate embryo model.

PubMed

Bladen, Catherine L; Kozlowski, David J; Dynan, William S

2012-11-01

Prior work has established the zebrafish embryo as an in vivo model for studying the biological effects of exposure to low doses of ionizing radiation. One of the known effects of radiation is to elevate the levels of reactive oxygen species (ROS) in tissue. However, ROS are also produced as by-products of normal metabolism and, regardless of origin, ROS produce similar chemical damage to DNA. Here we use the zebrafish embryo model to investigate whether the effects of low-dose (0-1.5 Gy) radiation and endogenous ROS are mechanistically distinct. We increased levels of endogenous ROS by exposure to low concentrations of the quinone drug, menadione. Imaging studies in live embryos showed that exposure to 3 μM or higher concentrations of menadione dramatically increased ROS levels. This treatment was associated with a growth delay and morphologic abnormalities, which were partially or fully reversible. By contrast, exposure to low doses of ionizing radiation had no discernable effects on overall growth or morphology, although, there was an increase in TUNEL-positive apoptotic cells, consistent with the results of prior studies. Further studies showed that the combined effect of radiation and menadione exposure are greater than with either agent alone, and that attenuation of the expression of Ku80, a gene important for repair of radiation-induced DNA damage, had only a slight effect on menadione sensitivity. Together, results suggest that ionizing radiation and menadione affect the embryo by distinct mechanisms.

The effect of low dose ionizing radiation on homeostasis and functional integrity in an organotypic human skin model

DOE Office of Scientific and Technical Information (OSTI.GOV)

von Neubeck, Claere; Geniza, Matthew; Kauer, Paula M.

Outside the protection of earth’s atmosphere, astronauts are exposed to low doses of high linear energy transfer (LET) radiation. Future NASA plans for deep space missions or a permanent settlement on the moon are limited by the health risks associated with space radiation exposures. There is a paucity of direct epidemiological data for low dose exposures to space radiation-relevant high LET ions. Health risk models are used to estimate the risk for such exposures, though these models are based on high dose experiments. There is increasing evidence, however, that low and high dose exposures result in different signaling events atmore » the molecular level, and may involve different response mechanisms. Further, despite their low abundance, high LET particles have been identified as the major contributor to health risk during manned space flight. The human skin is exposed in every external radiation scenario, making it an ideal epithelial tissue model in which to study radiation induced effects. Here, we exposed an in vitro three dimensional (3-D) human organotypic skin tissue model to low doses of high LET oxygen (O), silicon (Si) and iron (Fe) ions. We measured proliferation and differentiation profiles in the skin tissue and examined the integrity of the skin’s barrier function. We discuss the role of secondary particles in changing the proportion of cells receiving a radiation dose, emphasizing the possible impact on radiation-induced health issues in astronauts.« less

The effect of work system on the hand exposure of workers in 18F-FDG production centres.

PubMed

Wrzesień, Małgorzata

2018-05-07

The production of the 18 F isotope-the marker of deoxyglucose ( 18 F-FDG)-the radiopharmaceutical most commonly used in the oncological diagnostic technique of positron emission tomography, requires a cyclotron device. At present, there are nine facilities working in Poland that are equipped with cyclotrons used for producing the short-lived isotopes. The aim of the paper is to determine the hand exposure of workers employed in the two 18 F-FDG production centres taking in to account the production procedures and work system in those facilities. Measurements, which included all professional workers exposed to ionizing radiation that were employed in two facilities, were performed by using high-sensitivity thermoluminescent detectors during the routine activities of the personnel. The work system used at the production centre has an impact on the level of the recorded doses. Among the production procedures performed by the staff, the highest ionizing radiation doses have been received by the staff during the 18 F-FDG quality control. The maximum estimated annual Hp(0.07) for chemists from the quality control department can exceed the annual skin limit dose (500 mSv). The source of lowest doses on the hands are the cyclotron operating procedure and the 18 F-FDG production, provided that these procedures can't be combined with other production procedures.

Total Dose Effects of Ionizing and Non-Ionizing Radiation on Piezoresistive Pressure Transducer Chips

DTIC Science & Technology

2003-03-01

facility and Mr. Joseph Talnagi of the Ohio State Research Reactor facility for their personal guidance and insight into reactor dosimetry and neutron...62 Test C1: Dosimetry ..................................................................................................... 63 Special...66 Annex A-3. Preliminary Dosimetry Calculations

Characterization of a synthetic single crystal diamond detector for dosimetry in spatially fractionated synchrotron x-ray fields.

PubMed

Livingstone, Jayde; Stevenson, Andrew W; Butler, Duncan J; Häusermann, Daniel; Adam, Jean-François

2016-07-01

Modern radiotherapy modalities often use small or nonstandard fields to ensure highly localized and precise dose delivery, challenging conventional clinical dosimetry protocols. The emergence of preclinical spatially fractionated synchrotron radiotherapies with high dose-rate, sub-millimetric parallel kilovoltage x-ray beams, has pushed clinical dosimetry to its limit. A commercially available synthetic single crystal diamond detector designed for small field dosimetry has been characterized to assess its potential as a dosimeter for synchrotron microbeam and minibeam radiotherapy. Experiments were carried out using a synthetic diamond detector on the imaging and medical beamline (IMBL) at the Australian Synchrotron. The energy dependence of the detector was characterized by cross-referencing with a calibrated ionization chamber in monoenergetic beams in the energy range 30-120 keV. The dose-rate dependence was measured in the range 1-700 Gy/s. Dosimetric quantities were measured in filtered white beams, with a weighted mean energy of 95 keV, in broadbeam and spatially fractionated geometries, and compared to reference dosimeters. The detector exhibits an energy dependence; however, beam quality correction factors (kQ) have been measured for energies in the range 30-120 keV. The kQ factor for the weighted mean energy of the IMBL radiotherapy spectrum, 95 keV, is 1.05 ± 0.09. The detector response is independent of dose-rate in the range 1-700 Gy/s. The percentage depth dose curves measured by the diamond detector were compared to ionization chambers and agreed to within 2%. Profile measurements of microbeam and minibeam arrays were performed. The beams are well resolved and the full width at halfmaximum agrees with the nominal width of the beams. The peak to valley dose ratio (PVDR) calculated from the profiles at various depths in water agrees within experimental error with PVDR calculations from Gafchromic film data. The synthetic diamond detector is now well characterized and will be used to develop an experimental dosimetry protocol for spatially fractionated synchrotron radiotherapy.

Malfunction of cardiac devices after radiotherapy without direct exposure to ionizing radiation: mechanisms and experimental data.

PubMed

Zecchin, Massimo; Morea, Gaetano; Severgnini, Mara; Sergi, Elisabetta; Baratto Roldan, Anna; Bianco, Elisabetta; Magnani, Silvia; De Luca, Antonio; Zorzin Fantasia, Anna; Salvatore, Luca; Milan, Vittorino; Giannini, Gianrossano; Sinagra, Gianfranco

2016-02-01

Malfunctions of cardiac implantable electronical devices (CIED) have been described after high-energy radiation therapy even in the absence of direct exposure to ionizing radiation, due to diffusion of neutrons (n) causing soft errors in inner circuits. The purpose of the study was to analyse the effect of scattered radiation on different types and models of CIED and the possible sources of malfunctions. Fifty-nine explanted CIED were placed on an anthropomorphous phantom of tissue-equivalent material, and a high-energy photon (15 MV) radiotherapy course (total dose = 70 Gy) for prostate treatment was performed. All devices were interrogated before and after radiation. Radiation dose, the electromagnetic field, and neutron fluence at the CIED site were measured. Thirty-four pacemakers (PM) and 25 implantable cardioverter-defibrillators (ICD) were analysed. No malfunctions were detected before radiation. After radiation a software malfunction was evident in 13 (52%) ICD and 6 (18%) PM; no significant electromagnetic field or photon radiations were detected in the thoracic region. Neutron capture was demonstrated by the presence of the (198)Au((197)Au + n) or (192)Ir((191)Ir + n) isotope activation; it was significantly greater in ICD than in PM and non-significantly greater in damaged devices. A greater effect in St Jude PM (2/2 damaged), Boston (9/11), and St Jude ICD (3/6) and in older ICD models was observed; the year of production was not relevant in PM. High-energy radiation can cause different malfunctions on CIED, particularly ICD, even without direct exposure to ionizing radiation due to scattered radiation of neutrons produced by the linear accelerator. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

AN ESTIMATION OF THE EXPOSURE OF THE POPULATION OF ISRAEL TO NATURAL SOURCES OF IONIZING RADIATION.

PubMed

Epstein, L; Koch, J; Riemer, T; Haquin, G; Orion, I

2017-11-01

The radiation dose to the population of Israel due to exposure to natural sources of ionizing radiation was assessed. The main contributor to the dose is radon that accounts for 60% of the exposure to natural sources. The dose due to radon inhalation was assessed by combining the results of a radon survey in single-family houses with the results of a survey in apartments in multi-storey buildings. The average annual dose due to radon inhalation was found to be 1.2 mSv. The dose rate due to exposure to cosmic radiation was assessed using a code that calculates the dose rate at different heights above sea level, taking into account the solar cycle. The annual dose was calculated based on the fraction of time spent indoors and the attenuation provided by buildings and was found to be 0.2 mSv. The annual dose due to external exposure to the terrestrial radionuclides was similarly assessed. The indoor dose rate was calculated using a model that takes into account the concentrations of the natural radionuclides in building materials, the density and the thickness of the walls. The dose rate outdoors was calculated based on the concentrations of the natural radionuclides in different geological units in Israel as measured in an aerial survey and measurements above ground. The annual dose was found to be 0.2 mSv. Doses due to internal exposure other than exposure to radon were also calculated and were found to be 0.4 mSv. The overall annual exposure of the population of Israel to natural sources of ionizing radiation is therefore 2 mSv and ranges between 1.7 and 2.7 mSv. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

End-to-end tests using alanine dosimetry in scanned proton beams

NASA Astrophysics Data System (ADS)

Carlino, A.; Gouldstone, C.; Kragl, G.; Traneus, E.; Marrale, M.; Vatnitsky, S.; Stock, M.; Palmans, H.

2018-03-01

This paper describes end-to-end test procedures as the last fundamental step of medical commissioning before starting clinical operation of the MedAustron synchrotron-based pencil beam scanning (PBS) therapy facility with protons. One in-house homogeneous phantom and two anthropomorphic heterogeneous (head and pelvis) phantoms were used for end-to-end tests at MedAustron. The phantoms were equipped with alanine detectors, radiochromic films and ionization chambers. The correction for the ‘quenching’ effect of alanine pellets was implemented in the Monte Carlo platform of the evaluation version of RayStation TPS. During the end-to-end tests, the phantoms were transferred through the workflow like real patients to simulate the entire clinical workflow: immobilization, imaging, treatment planning and dose delivery. Different clinical scenarios of increasing complexity were simulated: delivery of a single beam, two oblique beams without and with range shifter. In addition to the dose comparison in the plastic phantoms the dose obtained from alanine pellet readings was compared with the dose determined with the Farmer ionization chamber in water. A consistent systematic deviation of about 2% was found between alanine dosimetry and the ionization chamber dosimetry in water and plastic materials. Acceptable agreement of planned and delivered doses was observed together with consistent and reproducible results of the end-to-end testing performed with different dosimetric techniques (alanine detectors, ionization chambers and EBT3 radiochromic films). The results confirmed the adequate implementation and integration of the new PBS technology at MedAustron. This work demonstrates that alanine pellets are suitable detectors for end-to-end tests in proton beam therapy and the developed procedures with customized anthropomorphic phantoms can be used to support implementation of PBS technology in clinical practice.

SU-E-T-66: A Prototype for Couch Based Real-Time Dosimetry in External Beam Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramachandran, P

Purpose: The main purpose of this study is to design a prototype for couch-based based real time dosimetry system in external beam radiotherapy Methods: A prototype of 100 ionization chambers was designed on a printed circuit board by etching the copper layer and each ionization chamber was wired to a 50 pin connector. The signals from the two 50 pin connectors collected from the ionization chambers were then transferred to a PXI module from National Instruments. The PXI module houses a current amplifier that amplifies the charge collected from the ionization chamber. The amplified signal is then sent to amore » digital multimeter module for converting the analog signal to digital signal. A software was designed in labview to read and display the signals obtained from the PXI module. A couch attachment frame was designed to house the 100 ionization chamber module. The frame was fixed underneath the treatment couch for measuring the dose during treatment. Resutls: The ionization chamber based prototype dosimetry was tested for simple radiotherapy treatment fields and found to be a useful device for measuring real time dosimetry at the treatment couch plane. This information could be used to assess the delivered dose to a patient during radiotherapy. It could be used as an invivo dosimeter during radiotherapy. Conclusion: In this study, a prototype for couch based real time dosimetry system was designed and tested. The prototype forms a basis for the development of large scale couch based real time dosimetry system that could be used to perform morning QA prior to treatment, assess real time doses delivered to patient and as a device to monitor the output of the treatment beam. Peter MacCallum Cancer Foundation.« less

Prototype Operational Advances for Atmospheric Radiation Dose Rate Specification

NASA Astrophysics Data System (ADS)

Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Garrett, H. B.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, D.; Mertens, C. J.; Xu, X.; Crowley, G.; Reynolds, A.; Azeem, I.; Wiltberger, M. J.; Wiley, S.; Bacon, S.; Teets, E.; Sim, A.; Dominik, L.

2014-12-01

Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. The coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has developed innovative, new space weather observations that will become part of the toolset that is transitioned into operational use. One prototype operational system for providing timely information about the effects of space weather is SET's Automated Radiation Measurements for Aerospace Safety (ARMAS) system. ARMAS will provide the "weather" of the radiation environment to improve aircraft crew and passenger safety. Through several dozen flights the ARMAS project has successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time via Iridium satellites, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. We are extending the dose measurement domain above commercial aviation altitudes into the stratosphere with a collaborative project organized by NASA's Armstrong Flight Research Center (AFRC) called Upper-atmospheric Space and Earth Weather eXperiment (USEWX). In USEWX we will be flying on the ER-2 high altitude aircraft a micro dosimeter for effective dose rate measurements and a thermal neutron monitor to characterize Single Event Effects (SEEs) in avionics. In this presentation we describe recent ARMAS and USEWX advances that will ultimately provide operational users with real-time dose and dose rate data for human tissue and avionics exposure risk mitigation.

Dose and linear energy transfer spectral measurements for the supersonic transport program

NASA Technical Reports Server (NTRS)

Philbrick, R. B.

1972-01-01

The purpose of the package, called the high altitude radiation instrumentation system (HARIS), is to measure the radiation hazard to supersonic transport passengers from solar and galactic cosmic rays. The HARIS includes gaseous linear energy transfer spectrometer, a tissue equivalent ionization chamber, and a geiger meuller tube. The HARIS is flown on RB-57F aircraft at 60,000 feet. Data from the HARIS are reduced to give rad and rem dose rates measured by the package during the flights. Results presented include ambient data obtained on background flights, altitude comparison data, and solar flare data.

Contaminated Human Remains: Transportable Decontamination - 1. Technical Readiness Level Estimate. 2. Vaccinia Virus Ionizing Radiation Inactivation in a Human Phantom. 3. Current State of Technology Relevant to Development of a Transportable System for Treatment of Contaminated Human Remains

DTIC Science & Technology

2011-05-30

affect chemical agents. Therefore no change in the methods for chemical or radiological decontamination would be necessary. 14. Radiation...here is the high radiation doses do affect the ability to polymerase chain reaction methods. It appears, depending on the dose and target, these...2001) Bacillus spore inactivation methods affect detection assays. Appl Environ Microbiol. 67(8): p. 3665‐70. DeCarlos, A. and Paez, E. (1991

Models of CNS radiation damage during space flight

NASA Astrophysics Data System (ADS)

Hopewell, J. W.

1994-10-01

The primary structural and functional arrangement of the different cell types within the CNS are reviewed. This was undertaken with a view to providing a better understanding of the complex interrelationships that may contribute to the pathogenesis of lesions in this tissue after exposure to ionizing radiation. The spectrum of possible CNS radiation-induced syndromes are discussed although not all have an immediate relevance to exposure during space flight. The specific characteristics of the lesions observed would appear to be dose related. Very high doses may produce an acute CNS syndrome that can cause death. Of the delayed lesions, selective coagulation necrosis of white matter and a later appearing vascular microangiopathy, have been reported in patients after cancer therapy doses. Lower doses, perhaps very low doses, may produce a delayed generalised CNS atrophy; this effect and the probability of the induction of CNS tumors could potentially have the greatest significance for space flight.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrotriya, D., E-mail: shrotriya2007@gmail.com; Srivastava, R. N. L.; Kumar, S.

The accurate dose delivery to the clinical target volume in radiotherapy can be affected by various pelvic tissues heterogeneities. An in-house heterogeneous woman pelvic phantom was designed and used to verify the consistency and computational capability of treatment planning system of radiation dose delivery in the treatment of cancer cervix. Oncentra 3D-TPS with collapsed cone convolution (CCC) dose calculation algorithm was used to generate AP/PA and box field technique plan. the radiation dose was delivered by Primus Linac (Siemens make) employing high energy 15 MV photon beam by isocenter technique. A PTW make, 0.125cc ionization chamber was used for directmore » measurements at various reference points in cervix, bladder and rectum. The study revealed that maximum variation between computed and measured dose at cervix reference point was 1% in both the techniques and 3% and 4% variation in AP/PA field and 5% and 4.5% in box technique at bladder and rectum points respectively.« less

Low doses of ionizing radiation to mammalian cells may rather control than cause DNA damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feinendegen, L.E.; Bond, V.P.; Sondhaus, C.A.

This report examines the origin of tissue effects that may follow from different cellular responses to low-dose irradiation, using published data. Two principal categories of cellular responses are considered. One response category relates to the probability of radiation-induced DNA damage. The other category consists of low-dose induced metabolic changes that induce mechanisms of DNA damage mitigation, which do not operate at high levels of exposure. Modeled in this way, tissue is treated as a complex adaptive system. The interaction of the various cellular responses results in a net tissue dose-effect relation that is likely to deviate from linearity in themore » low-dose region. This suggests that the LNT hypothesis should be reexamined. This paper aims at demonstrating tissue effects as an expression of cellular responses, both damaging and defensive, in relation to the energy deposited in cell mass, by use of microdosimetric concepts.« less

Patient Radiation Doses from Diagnostic Radiology.

ERIC Educational Resources Information Center

Hart, D.

1996-01-01

Explains how x-ray doses to patients are measured. Describes how different techniques expose patients to differing amounts of ionizing radiation. Compares these figures with other natural and man-made sources. (Author/MKR)

Patient-specific IMRT verification using independent fluence-based dose calculation software: experimental benchmarking and initial clinical experience.

PubMed

Georg, Dietmar; Stock, Markus; Kroupa, Bernhard; Olofsson, Jörgen; Nyholm, Tufve; Ahnesjö, Anders; Karlsson, Mikael

2007-08-21

Experimental methods are commonly used for patient-specific intensity-modulated radiotherapy (IMRT) verification. The purpose of this study was to investigate the accuracy and performance of independent dose calculation software (denoted as 'MUV' (monitor unit verification)) for patient-specific quality assurance (QA). 52 patients receiving step-and-shoot IMRT were considered. IMRT plans were recalculated by the treatment planning systems (TPS) in a dedicated QA phantom, in which an experimental 1D and 2D verification (0.3 cm(3) ionization chamber; films) was performed. Additionally, an independent dose calculation was performed. The fluence-based algorithm of MUV accounts for collimator transmission, rounded leaf ends, tongue-and-groove effect, backscatter to the monitor chamber and scatter from the flattening filter. The dose calculation utilizes a pencil beam model based on a beam quality index. DICOM RT files from patient plans, exported from the TPS, were directly used as patient-specific input data in MUV. For composite IMRT plans, average deviations in the high dose region between ionization chamber measurements and point dose calculations performed with the TPS and MUV were 1.6 +/- 1.2% and 0.5 +/- 1.1% (1 S.D.). The dose deviations between MUV and TPS slightly depended on the distance from the isocentre position. For individual intensity-modulated beams (total 367), an average deviation of 1.1 +/- 2.9% was determined between calculations performed with the TPS and with MUV, with maximum deviations up to 14%. However, absolute dose deviations were mostly less than 3 cGy. Based on the current results, we aim to apply a confidence limit of 3% (with respect to the prescribed dose) or 6 cGy for routine IMRT verification. For off-axis points at distances larger than 5 cm and for low dose regions, we consider 5% dose deviation or 10 cGy acceptable. The time needed for an independent calculation compares very favourably with the net time for an experimental approach. The physical effects modelled in the dose calculation software MUV allow accurate dose calculations in individual verification points. Independent calculations may be used to replace experimental dose verification once the IMRT programme is mature.

Laser-plasma accelerator and femtosecond photon sources-based ultrafast radiation chemistry and biophysics

NASA Astrophysics Data System (ADS)

Gauduel, Y. A.

2017-02-01

The initial distribution of energy deposition triggered by the interaction of ionizing radiations (far UV and X rays, electron, proton and accelerated ions) with molecular targets or integrated biological systems is often decisive for the spatio-temporal behavior of radiation effects that take place on several orders of magnitude. This contribution deals with an interdisciplinary approach that concerns cutting-edge advances on primary radiation events, considering the potentialities of innovating strategies based on ultrafast laser science, from femtosecond photon sources to laser-driven relativistic particles acceleration. Recent advances of powerful TW laser sources (~ 1019 Wcm-2) and laser-plasma interactions providing ultrashort relativistic particle beams in the energy domain 2.5-150 MeV open exciting opportunities for the development of high-energy radiation femtochemistry (HERF). Early radiation damages being dependent on the survival probability of secondary electrons and radial distribution of short-lived radicals inside ionization clusters, a thorough knowledge of these processes involves the real-time probing of primary events in the temporal range 10-14-10-11 s. In the framework of a closed synergy between low-energy radiation femtochemistry (LERF) and the emerging domain of HERF, the paper focuses on early phenomena that occur in the prethermal regime of low-energy secondary electrons, considering very short-lived quantum effects in aqueous environments. A high dose-rate delivered by femtosecond electron beam (~ 1011-1013 Gy s-1) can be used to investigate early radiation processes in native ionization tracks, down to 10-12 s and 10-9 m. We explain how this breakthrough favours the innovating development of real-time nanodosimetry in biologically relevant environments and open new perspectives for spatio-temporal radiation biophysics. The emerging domain of HERF would provide guidance for understanding the specific bioeffects of ultrashort particle bunches. This domain represents also a prerequisite for the control of in vitro and in vivo irradiation at ultrahigh dose-rates or the investigation of ultrafast dose-fractionating phenomena.

An online proton beam monitor for cancer therapy based on ionization chambers with micro pattern readout

NASA Astrophysics Data System (ADS)

Basile, E.; Carloni, A.; Castelluccio, D. M.; Cisbani, E.; Colilli, S.; De Angelis, G.; Fratoni, R.; Frullani, S.; Giuliani, F.; Gricia, M.; Lucentini, M.; Santavenere, F.; Vacca, G.

2012-03-01

A unique compact LINAC accelerator for proton therapy is under development in Italy within the TOP-IMPLART project. The proton beam will reach the kinetic energy of 230 MeV, it will have a widely variable current intensity (0.1-10 μA, with average up to 3.5 nA) associated with a high pulse repetition frequency (1-3.5 μs long pulses at 10-100 Hz). The TOP-IMPLART system will provide a fully active 3+1D dose delivery, that is longitudinal (energy modulation), transverse active spot scanning, and current intensity modulation. These accelerator features will permit a highly conformational dose distribution, which therefore requires an effective, online, beam monitor system with wide dynamic range, good sensitivity, adequate spatial resolution and rapid response. In order to fulfill these requisites a new device is under development for the monitoring of the beam intensity profile, its centroid and direction; it is based on transmission, segmented, ionization chambers with typical active area of 100 × 100 mm2. Micro pattern x/y pad like design has been used for the readout plane in order to maximize the field uniformity, reduce the chamber thickness and obtain both beam coordinates on a single chamber. The chamber prototype operates in ionization region to minimize saturation and discharge effects. Simulations (based on FLUKA) have been carried on to study the perturbation of the chamber on the beam parameters and the effects on the delivered dose (on a water phantom). The charge collected in each channel is integrated by dedicated auto-ranging readout electronics: an original scheme has been developed in order to have an input dynamic range greater than 104 with sensitivity better than 3%. This is achieved by a dynamical adjustment of the integrating capacitance to the signal intensity.

ADVISORY ON UPDATED METHODOLOGY FOR ...

EPA Pesticide Factsheets

The National Academy of Sciences (NAS) published the Biological Effects of Ionizing Radiation (BEIR) committee's report (BEIR VII) on risks from ionizing radiation exposures in 2006. The Committee analyzed the most recent epidemiology from the important exposed cohorts and factored in changes resulting from the updated analysis of dosimetry for the Japanese atomic bomb survivors. To the extent practical, the Committee also considered relevant radiobiological data, including that from the Department of Energy's low dose effects research program. Based on the review of this information, the Committee proposed a set of models for estimating risks from low-dose ionizing radiation. ORIA then prepared a white paper revising the Agency's methodology for estimating cancer risks from exposure to ionizing radiation in light of this report and other relevant information. This is the first product to be developed as a result of the BEIR VII report. We requested that the SAB conduct an advisory during the development of this methodology. The second product to be prepared will be a revised version of the document,

Decomposition of persistent pharmaceuticals in wastewater by ionizing radiation

NASA Astrophysics Data System (ADS)

Kimura, Atsushi; Osawa, Misako; Taguchi, Mitsumasa

2012-09-01

Pharmaceuticals in wastewater were treated by the combined method of activated sludge and ionizing radiation in laboratory scale. Oseltamivir, aspirin, and ibuprofen at 5 μmol dm-3 in wastewater were decomposed by the activated sludge at reaction time for 4 h. Carbamazepine, ketoprofen, mefenamic acid, clofibric acid, and diclofenac were not biodegraded completely, but were eliminated by γ-ray irradiation at 2 kGy. The rate constants of the reactions of these pharmaceuticals with hydroxyl radicals were estimated by the competition reaction method to be 4.0-10×109 mol-1 dm3 s-1. Decompositions of the pharmaceuticals in wastewater by ionizing radiation were simulated by use of the rate constants and the amount of total organic carbon as parameters. Simulation curves of concentrations of these pharmaceuticals as a function of dose described the experimental data, and the required dose for the elimination of them in wastewater by ionizing radiation can be estimated by this simulation.

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

PubMed

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

2011-06-03

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

Non-Malignant Thyroid Diseases Following a Wide Range of Radiation Exposures

PubMed Central

Ron, Elaine; Brenner, Alina

2013-01-01

Background The thyroid gland is one of the most radiosensitive human organs. While it is well known that radiation exposure increases the risk of thyroid cancer, less is known about its effects in relation to non-malignant thyroid diseases. Objectives The aim of this review is to evaluate the effects of high and low dose radiation on benign structural and functional diseases of the thyroid. Methods We examined the results of major studies from cancer patients treated with high-dose radiotherapy or thyrotoxicosis patients treated with high doses of iodine-131, patients treated with moderate to high dose radiotherapy for benign diseases, persons exposed to low doses from environmental radiation and survivors of the atomic bombings who were exposed to a range of doses. We evaluated radiation effects on structural (tumors, nodules), functional (hyper- and hypothyroidism), and autoimmune thyroid diseases. Results Following a wide range of doses of ionizing radiation, an increased risk of thyroid adenomas and nodules was observed in a variety of populations and settings. The dose response appeared to be linear at low to moderate doses, but in one study there was some suggestion of a reduction in risk above 5 Gy. The elevated risk for benign tumors continues for decades following exposure. Considerably less consistent findings are available regarding functional thyroid diseases including autoimmune diseases. In general, associations for these outcomes were fairly weak and significant radiation effects were most often observed following high doses, particularly for hypothyroidism. Conclusions A significant radiation dose-response relation was demonstrated for benign nodules and follicular adenomas. The effects of radiation on functional thyroid diseases are less clear, partly due to the greater difficulties studying these diseases. PMID:21128812

Feasibility study of a lead(II) iodide-based dosimeter for quality assurance in therapeutic radiology

NASA Astrophysics Data System (ADS)

Heo, Y. J.; Kim, K. T.; Oh, K. M.; Lee, Y. K.; Ahn, K. J.; Cho, H. L.; Kim, J. Y.; Min, B. I.; Mun, C. W.; Park, S. K.

2017-09-01

The most widely used form of radiotherapy to treat tumors uses a linear accelerator, and the apparatus requires regular quality assurance (QA). QA for a linear accelerator demands accuracy throughout, from mock treatment and treatment planning, up to treatment itself. Therefore, verifying a radiation dose is essential to ensure that the radiation is being applied as planned. In current clinical practice, ionization chambers and diodes are used for QA. However, using conventional gaseous ionization chambers presents drawbacks such as complex analytical procedures, difficult measurement procedures, and slow response time. In this study, we discuss the potential of a lead(II) iodide (PbI2)-based radiation dosimeter for radiotherapy QA. PbI2 is a semiconductor material suited to measurements of X-rays and gamma rays, because of its excellent response properties to radiation signals. Our results show that the PbI2-based dosimeter offers outstanding linearity and reproducibility, as well as dose-independent characteristics. In addition, percentage depth dose (PDD) measurements indicate that the error at a fixed reference depth Dmax was 0.3%, very similar to the measurement results obtained using ionization chambers. Based on these results, we confirm that the PbI2-based dosimeter has all the properties required for radiotherapy: stable dose detection, dose linearity, and rapid response time. Based on the evidence of this experimental verification, we believe that the PbI2-based dosimeter could be used commercially in various fields for precise measurements of radiation doses in the human body and for measuring the dose required for stereotactic radiosurgery or localized radiosurgery.

Method of making a scintillator waveguide

DOEpatents

Bliss, Mary; Craig, Richard A.; Reeder, Paul L.

2000-01-01

The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

Scintillator Waveguide For Sensing Radiation

DOEpatents

Bliss, Mary; Craig, Richard A.; Reeder; Paul L.

2003-04-22

The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

Total Ionizing Dose Effects on Ge Channel $p$FETs with Raised $${\\rm Si}_{0.55}{\\rm Ge}_{0.45}$$ Source/Drain

DOE PAGES

Wang, Liang; Zhang, En Xia; Schrimpf, Ronald D.; ...

2015-12-17

Here, the total ionizing dose response of Ge channel pFETs with raised Si 0.55Ge 0.45 source/drain is investigated under different radiation bias conditions. Threshold-voltage shifts and transconductance degradation are noticeable only for negative-bias (on state) irradiation, and are mainly due to negative bias-temperature instability (NBTI). Nonmonotonic leakage changes during irradiation are observed, which are attributed to the competition of radiation-induced field transistor leakage and S/D junction leakage.

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

PubMed

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

2016-08-20

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

Preclinical development of a bridging therapy for radiation casualties: appropriate for high risk personnel.

PubMed

Singh, Vijay K; Wise, Stephen Y; Fatanmi, Oluseyi O; Beattie, Lindsay A; Seed, Thomas M

2014-06-01

The authors demonstrate the efficacy of a bridging therapy in a preclinical animal model that allows the lymphohematopoietic system of severely immunocompromised individuals exposed to acute, high-dose ionizing irradiation to recover and to survive. CD2F1 mice were irradiated acutely with high doses causing severe, potentially fatal hematopoietic or gastrointestinal injuries and then transfused intravenously with progenitor-enriched, whole blood, or peripheral blood mononuclear cells from mice injected with tocopherol succinate- and AMD3100- (a chemokine receptor anatogonist used to improve the yield of mobilized progenitors). Survival of these mice over a 30-d period was used as the primary measured endpoint of therapeutic effectiveness. The authors demonstrate that tocopherol succinate and AMD3100 mobilize progenitors into peripheral circulation and that the infusion of mobilized progenitor enriched blood or mononuclear cells acts as a bridging therapy for lymphohematopoietic system recovery in mice exposed to whole-body ionizing irradiation. The results demonstrate that infusion of whole blood or blood mononuclear cells from tocopherol succinate (TS)- and AMD3100-injected mice improved the survival of mice receiving high radiation doses significantly. The efficacy of TS-injected donor mice blood or mononuclear cells was comparable to that of blood or cells obtained from mice injected with granulocyte colony-stimulating factor. Donor origin-mobilized progenitors were found to localize in various tissues. The authors suggest that tocopherol succinate is an optimal agent for mobilizing progenitors with significant therapeutic potential. The extent of progenitor mobilization that tocopherol succinate elicits in experimental mice is comparable quantitatively to clinically used drugs such as granulocyte-colony stimulating factor and AMD3100. Therefore, it is proposed that tocopherol succinate be considered for further translational development and ultimately for use in humans.

Gold nanoparticles and their alternatives for radiation therapy enhancement

PubMed Central

Cooper, Daniel R.; Bekah, Devesh; Nadeau, Jay L.

2014-01-01

Radiation therapy is one of the most commonly used treatments for cancer. The dose of delivered ionizing radiation can be amplified by the presence of high-Z materials via an enhancement of the photoelectric effect; the most widely studied material is gold (atomic number 79). However, a large amount is needed to obtain a significant dose enhancement, presenting a challenge for delivery. In order to make this technique of broader applicability, the gold must be targeted, or alternative formulations developed that do not rely solely on the photoelectric effect. One possible approach is to excite scintillating nanoparticles with ionizing radiation, and then exploit energy transfer between these particles and attached dyes in a manner analogous to photodynamic therapy (PDT). Doped rare-earth halides and semiconductor quantum dots have been investigated for this purpose. However, although the spectrum of emitted light after radiation excitation is usually similar to that seen with light excitation, the yield is not. Measurement of scintillation yields is challenging, and in many cases has been done only for bulk materials, with little understanding of how the principles translate to the nanoscale. Another alternative is to use local heating using gold or iron, followed by application of ionizing radiation. Hyperthermia pre-sensitizes the tumors, leading to an improved response. Another approach is to use chemotherapeutic drugs that can radiosensitize tumors. Drugs may be attached to high-Z nanoparticles or encapsulated. This article discusses each of these techniques, giving an overview of the current state of nanoparticle-assisted radiation therapy and future directions. PMID:25353018

Ionizing diagnostic radiation exposure in patients with Crohn's disease: A retrospective study in a medium hospital and its predictive factors.

PubMed

Merino Rodríguez, Esther; Carrera Alonso, Elisa; Torralba González de Suso, Miguel; Sánchez da Silva, Marta; Martínez López, María; Sánchez-Tembleque Zarandona, María Dolores

2018-02-01

It is estimated that diagnostic medical radiation exposure may be responsable for 0.5-2% of cancers worldwide. Because of the relapsing course of Crohn's disease (CD), these patients usually requiere multiple ionizing radiation test. Stimating the total cumulative effective dose received by our CD patients and identifying the risk factors associated with the exposure to a cumulative effective dose due to the disease (CEED) > 50mSv. Retrospective cohort study (2001-2014). patients with CD. Risk dose >50mSv. For calculating de cumulative effective dose and the CEED, all the ionizing test done were taken. For identifying predictive factors for receiving a CEDD >50mSv, an univariate and a multivariate logistic regression analyses were performed using a >50mSv dose as dependent variable. Of the 267 patients analyzed the 24.6% of them received a cumulative effective dose > 50mSv and the 15.2% a CEED>50mSv. In the multivariate analysis, the following variables were identified as independent predictors associated with a CEDD >50mSv: major surgery (OR= 2.1; IC 95% [1.1-3.8]; p=.019) and severity (OR= 20.6; IC 95% [4.5-94.8]; p<.01). Patients with CD are more at risk of receiving risk CEED, so it would be advisable to monitor the cumulative effective dose received to anticipate our intervention in order to avoid reaching that dose. The ultrasounds and abdominal resonance enterography are alternatives in these cases, although their accessibility is limited in some centers. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Early brain response to low-dose radiation exposure involves molecular networks and pathways associated with cognitive functions, advanced aging and Alzheimer's disease.

PubMed

Lowe, Xiu R; Bhattacharya, Sanchita; Marchetti, Francesco; Wyrobek, Andrew J

2009-01-01

Understanding the cognitive and behavioral consequences of brain exposures to low-dose ionizing radiation has broad relevance for health risks from medical radiation diagnostic procedures, radiotherapy and environmental nuclear contamination as well as for Earth-orbit and space missions. Analyses of transcriptome profiles of mouse brain tissue after whole-body irradiation showed that low-dose exposures (10 cGy) induced genes not affected by high-dose radiation (2 Gy) and that low-dose genes were associated with unique pathways and functions. The low-dose response had two major components: pathways that are consistently seen across tissues and pathways that were specific for brain tissue. Low-dose genes clustered into a saturated network (P < 10(-53)) containing mostly down-regulated genes involving ion channels, long-term potentiation and depression, vascular damage, etc. We identified nine neural signaling pathways that showed a high degree of concordance in their transcriptional response in mouse brain tissue after low-dose irradiation, in the aging human brain (unirradiated), and in brain tissue from patients with Alzheimer's disease. Mice exposed to high-dose radiation did not show these effects and associations. Our findings indicate that the molecular response of the mouse brain within a few hours after low-dose irradiation involves the down-regulation of neural pathways associated with cognitive dysfunctions that are also down-regulated in normal human aging and Alzheimer's disease.

Signal enhancement due to high-Z nanofilm electrodes in parallel plate ionization chambers with variable microgaps.

PubMed

Brivio, Davide; Sajo, Erno; Zygmanski, Piotr

2017-12-01

We developed a method for measuring signal enhancement produced by high-Z nanofilm electrodes in parallel plate ionization chambers with variable thickness microgaps. We used a laboratory-made variable gap parallel plate ionization chamber with nanofilm electrodes made of aluminum-aluminum (Al-Al) and aluminum-tantalum (Al-Ta). The electrodes were evaporated on 1 mm thick glass substrates. The interelectrode air gap was varied from 3 μm to 1 cm. The gap size was measured using a digital micrometer and it was confirmed by capacitance measurements. The electric field in the chamber was kept between 0.1 kV/cm and 1 kV/cm for all the gap sizes by applying appropriate compensating voltages. The chamber was exposed to 120 kVp X-rays. The current was measured using a commercial data acquisition system with temporal resolution of 600 Hz. In addition, radiation transport simulations were carried out to characterize the dose, D(x), high-energy electron current, J(x), and deposited charge, Q(x), as a function of distance, x, from the electrodes. A deterministic method was selected over Monte Carlo due to its ability to produce results with 10 nm spatial resolution without stochastic uncertainties. Experimental signal enhancement ratio, SER(G) which we defined as the ratio of signal for Al-air-Ta to signal for Al-air-Al for each gap size, was compared to computations. The individual contributions of dose, electron current, and charge deposition to the signal enhancement were determined. Experimental signals matched computed data for all gap sizes after accounting for several contributions to the signal: (a) charge carrier generated via ionization due to the energy deposited in the air gap, D(x); (b) high-energy electron current, J(x), leaking from high-Z electrode (Ta) toward low-Z electrode (Al); (c) deposited charge in the air gap, Q(x); and (d) the decreased collection efficiency for large gaps (>~500 μm). Q(x) accounts for the electrons below 100 eV, which are regarded as stopped by the radiation transport code but which can move and form electron current in small gaps (<100 μm). While the total energy deposited in the air gap increases with gap size for both samples, the average high-energy current and deposited charge are moderately decreasing with the air gap. When gap sizes are smaller than ~20 μm, the contribution to signal from dose approaches zero while contributions from high-energy current and deposited charges give rise to an offset signal. The measured signal enhancement ratio (SER) was 40.0 ± 5.0 for the 3 μm gap and rapidly decreasing with gap size down to 9.9 ± 1.2 for the 21 μm gap and to 6.6 ± 0.3 for the 100 μm gap. The uncertainties in SER were mostly due to uncertainties in gap size and data acquisition system. We developed an experimental method to determine the signal enhancement due to high-Z nanolayers in parallel plate ionization chambers with micrometer spatial resolution. As the water-equivalent thicknesses of these air gaps are 3 nm to 10 μm, the method may also be applicable for nanoscopic spatial resolution of other gap materials. The method may be extended to solid insulator materials with low Z. © 2017 American Association of Physicists in Medicine.

Ionizing radiation fluxes and dose measurements during the Kosmos 1887 satellite flight.

PubMed

Charvat, J; Spurny, F; Kopecka, B; Votockova, I

1990-01-01

The results of dosimetric experiments performed during the flight of Kosmos 1887 biosatellite are presented. Two kinds of measurements were performed on the external surface of the satellite. First, the fluences and spectra of low energy charged particles were established. It was found that most of the particles registered by means of solid state nuclear track detectors are helium nuclei. Tracks of oxygen nuclei and some heavier charged particles were also observed. Thermoluminescent detectors were used to establish absorbed doses in open space on the satellite's surface and behind thin shielding. It was found that these doses were rather high; nevertheless, their decrease with shielding thickness is very rapid. Dosimetric and other consequences of the results obtained are analyzed and discussed.

Effects of very low fluences of high-energy protons or iron ions on irradiated and bystander cells.

PubMed

Yang, H; Magpayo, N; Rusek, A; Chiang, I-H; Sivertz, M; Held, K D

2011-12-01

In space, astronauts are exposed to radiation fields consisting of energetic protons and high atomic number, high-energy (HZE) particles at very low dose rates or fluences. Under these conditions, it is likely that, in addition to cells in an astronaut's body being traversed by ionizing radiation particles, unirradiated cells can also receive intercellular bystander signals from irradiated cells. Thus this study was designed to determine the dependence of DNA damage induction on dose at very low fluences of charged particles. Novel techniques to quantify particle fluence have been developed at the NASA Space Radiation Biology Laboratory (NSRL) at Brookhaven National Laboratory (BNL). The approach uses a large ionization chamber to visualize the radiation beam coupled with a scintillation counter to measure fluence. This development has allowed us to irradiate cells with 1 GeV/nucleon protons and iron ions at particle fluences as low as 200 particles/cm(2) and quantify biological responses. Our results show an increased fraction of cells with DNA damage in both the irradiated population and bystander cells sharing medium with irradiated cells after low fluences. The fraction of cells with damage, manifest as micronucleus formation and 53BP1 focus induction, is about 2-fold higher than background at doses as low as ∼0.47 mGy iron ions (∼0.02 iron ions/cell) or ∼70 μGy protons (∼2 protons/cell). In the irradiated population, irrespective of radiation type, the fraction of damaged cells is constant from the lowest damaging fluence to about 1 cGy, above which the fraction of damaged cells increases with dose. In the bystander population, the level of damage is the same as in the irradiated population up to 1 cGy, but it does not increase above that plateau level with increasing dose. The data suggest that at fluences of high-energy protons or iron ions less than about 5 cGy, the response in irradiated cell populations may be dominated by the bystander response.

Radiation mapping on Spacelab 1: Experiment no. INS006

NASA Technical Reports Server (NTRS)

Benton, E. V.; Frank, A.; Cassou, R.; Henke, R.; Rowe, V.

1985-01-01

The first attempt at mapping the radiation environment inside Spacelab is described. Measurements were made by a set of passive radiation detectors distributed throughout the volume inside the Spacelab 1 module, in the access tunnel and outside on the pallet. Measurements of the low linear energy transfer (LET) component obtained from the TLD thermoluminescent detectors (TLD) ranged from 92 to 134 mrad, yielding an average low LET dose rate of 10.0 mrads/day inside the module. Because of the higher inclination orbit, substantial fluxes of highly ionizing (HZE particles) high charge and energy galactic cosmic rays were observed for the first time on an STS flight, yielding an overall average mission dose-equivalent of 295 mrem, or 29.5 mrem/day, which is about three times higher than that measured on previous STS missions. Little correlation is found between measured average dose rates or HZE fluences and the estimates shielding throughout the volume of the module.

Fault Tolerant Characteristics of Artificial Neural Network Electronic Hardware

NASA Technical Reports Server (NTRS)

Zee, Frank

1995-01-01

The fault tolerant characteristics of analog-VLSI artificial neural network (with 32 neurons and 532 synapses) chips are studied by exposing them to high energy electrons, high energy protons, and gamma ionizing radiations under biased and unbiased conditions. The biased chips became nonfunctional after receiving a cumulative dose of less than 20 krads, while the unbiased chips only started to show degradation with a cumulative dose of over 100 krads. As the total radiation dose increased, all the components demonstrated graceful degradation. The analog sigmoidal function of the neuron became steeper (increase in gain), current leakage from the synapses progressively shifted the sigmoidal curve, and the digital memory of the synapses and the memory addressing circuits began to gradually fail. From these radiation experiments, we can learn how to modify certain designs of the neural network electronic hardware without using radiation-hardening techniques to increase its reliability and fault tolerance.

SU-F-T-488: Comparison of the TG-51 and TG-51 Addendum Calibration Protocols

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCaw, T; Hwang, M; Jang, S

Purpose: To quantify differences between the TG51 and TG51 addendum calibration protocols. Methods: Beam energies of 6X, 6XSRS, 10X, 15X, 23X, 6XFFF, and 10XFFF were calibrated following both the TG51 and TG51 addendum protocols using both a Farmer and a scanning ionization chamber with traceable absorbed dose-to-water calibrations. For the TG51 addendum procedure, the collimating jaws were positioned to define a 10×10cm{sup 2} radiation field, a lead foil was only used for kQ measurements of FFF energies, and a volume-averaging correction was applied based on crossline and inline dose profiles. For the TG51 procedure, the collimating jaws were set tomore » 10×10cm{sup 2} according to the digital readout, and a lead foil was used for kQ measurements of energies greater than 10MV. Results: For beam energies with a flattening filter, absorbed dose-to-water determined by the two protocols differed by 0.1%–0.3%. For FFF beam energies, differences between the protocols were up to 0.2% and 0.8% for the scanning and Farmer ionization chambers, respectively. Differences between the protocols were due to kQ determination, volume-averaging correction, and measurement of raw ionization. Differences in kQ values between the two protocols were up to 0.4% and 0.2% for the scanning and Farmer ionization chambers, respectively. Volume-averaging corrections were less than 0.1% for the scanning ionization chamber, and up to 0.4% and 0.6% for the Farmer ionization chamber in beams with a flattening filter and FFF beams, respectively. Raw ionization measurements differed up to 0.3%±0.07% due to differences in jaw settings. Conclusion: The TG51 and TG51 addendum calibration protocols differed less than 0.3% for the scanning ionization chamber. For the Farmer chamber in FFF energies, volume-averaging corrections of up to 0.6% contributed to calibration differences of up to 0.8%. Failure to verify the radiation field size can produce calibration differences of up to 0.3%.« less

Ionizing radiation-induced acoustics for radiotherapy and diagnostic radiology applications.

PubMed

Hickling, Susannah; Xiang, Liangzhong; Jones, Kevin C; Parodi, Katia; Assmann, Walter; Avery, Stephen; Hobson, Maritza; El Naqa, Issam

2018-04-21

Acoustic waves are induced via the thermoacoustic effect in objects exposed to a pulsed beam of ionizing radiation. This phenomenon has interesting potential applications in both radiotherapy dosimetry and treatment guidance as well as low dose radiological imaging. After initial work in the field in the 1980s and early 1990s, little research was done until 2013 when interest was rejuvenated, spurred on by technological advances in ultrasound transducers and the increasing complexity of radiotherapy delivery systems. Since then, many studies have been conducted and published applying ionizing radiation-induced acoustic principles into three primary research areas: Linear accelerator photon beam dosimetry, proton therapy range verification, and radiological imaging. This review article introduces the theoretical background behind ionizing radiation-induced acoustic waves, summarizes recent advances in the field, and provides an outlook on how the detection of ionizing radiation-induced acoustic waves can be used for relative and in vivo dosimetry in photon therapy, localization of the Bragg peak in proton therapy, and as a low-dose medical imaging modality. Future prospects and challenges for clinical implementation of these techniques are discussed. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Health effects of prenatal radiation exposure.

PubMed

Williams, Pamela M; Fletcher, Stacy

2010-09-01

Pregnant women are at risk of exposure to nonionizing and ionizing radiation resulting from necessary medical procedures, workplace exposure, and diagnostic or therapeutic interventions before the pregnancy is known. Nonionizing radiation includes microwave, ultrasound, radio frequency, and electromagnetic waves. In utero exposure to nonionizing radiation is not associated with significant risks; therefore, ultrasonography is safe to perform during pregnancy. Ionizing radiation includes particles and electromagnetic radiation (e.g., gamma rays, x-rays). In utero exposure to ionizing radiation can be teratogenic, carcinogenic, or mutagenic. The effects are directly related to the level of exposure and stage of fetal development. The fetus is most susceptible to radiation during organogenesis (two to seven weeks after conception) and in the early fetal period (eight to 15 weeks after conception). Noncancer health effects have not been detected at any stage of gestation after exposure to ionizing radiation of less than 0.05 Gy (5 rad). Spontaneous abortion, growth restriction, and mental retardation may occur at higher exposure levels. The risk of cancer is increased regardless of the dose. When an exposure to ionizing radiation occurs, the total fetal radiation dose should be estimated and the mother counseled about the potential risks so that she can make informed decisions about her pregnancy management.

Overview of Non-Volatile Testing and Screening Methods

NASA Technical Reports Server (NTRS)

Irom, Farokh

2001-01-01

Testing methods for memories and non-volatile memories have become increasingly sophisticated as they become denser and more complex. High frequency and faster rewrite times as well as smaller feature sizes have led to many testing challenges. This paper outlines several testing issues posed by novel memories and approaches to testing for radiation and reliability effects. We discuss methods for measurements of Total Ionizing Dose (TID).

Confidence Level Based Approach to Total Dose Specification for Spacecraft Electronics

NASA Technical Reports Server (NTRS)

Xapsos, M. A.; Stauffer, C.; Phan, A.; McClure, S. S.; Ladbury, R. L.; Pellish, J. A.; Campola, M. J.; Label, K. A.

2017-01-01

A confidence level based approach to total dose radiation hardness assurance is presented for spacecraft electronics. It is applicable to both ionizing and displacement damage dose. Results are compared to the traditional approach that uses radiation design margin and advantages of the new approach are discussed.

Reference air kerma rate calibration system for high dose rate Ir-192 brachytherapy sources in Taiwan

NASA Astrophysics Data System (ADS)

Chu, Wei-Han; Yuan, Ming-Chen; Lee, Jeng-Hung; Lin, Yi-Chun

2017-11-01

Ir-192 sources are widely used in brachytherapy and the number of treatments is around seven thousand for the use of the high dose rate (HDR) Ir-192 brachytherapy source per year in Taiwan. Due to its physical half-life of 73.8 days, the source should be replaced four times per year to maintain the HDR treatment mode (DDEP, 2005; Coursey et al., 1992). When doing this work, it must perform the source dose trace to assure the dose accuracy. To establish the primary measurement standard of reference air kerma rate(RAKR) for the HDR Ir-192 brachytherapy sources in Taiwan, the Institute of Nuclear Energy Research (INER) fabricated a dual spherical graphite-walled cavity ionization chambers system to directly measure the RAKR of the Ir-192 brachytherapy source. In this system, the ion-charge was accumulated by the two ionization chambers and after correction for the ion recombination, temperature, atmosphere pressure, room scattering, graphite-wall attenuation, air attenuation, source decay, stem effect, and so on. The RAKR of the Ir-192 source was obtained in the ambient conditions of 22 °C and one atmosphere. The measurement uncertainty of the system was around 0.92% in 96% confidence level (k=2.0). To verify the accuracy of the result, the source calibration comparison has been made at the National Radiation Standard Laboratory (NRSL) of INER and Physikalisch-Technische Bundesanstalt (PTB, Germany) in 2015. The ratio of the measurement results between INER and PTB, INER/PTB, was 0.998±0.027 (k=2) which showed good consistency and the performance of the system was verified.

SU-F-T-154: An Evaluation and Quantification of Secondary Neutron Radiation Dose Due to Double Scatter and Pencil Beam Scanning Proton Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glick, A; Diffenderfer, E

2016-06-15

Proton radiation therapy can deliver high radiation doses to tumors while sparing normal tissue. However, protons yield secondary neutron and gamma radiation that is difficult to detect, small in comparison to the prescribed dose, and not accounted for in most treatment planning systems. The risk for secondary malignancies after proton therapy may be dependent on the quality of this dose. Consequently, there is interest in characterizing the secondary radiation. Previously, we used the dual ionization chamber method to measure the separate absorbed dose from gamma-rays and neutrons secondary to the proton beam1, relying on characterization of ionization chamber response inmore » the unknown neutron spectrum from Monte Carlo simulation. We developed a procedure to use Shieldwerx activation foils, with neutron activation energies ranging from 0.025 eV to 13.5 MeV, to measure the neutron energy spectrum from double scattering (DS) and pencil beam scanning (PBS) protons outside of the treatment volume in a water tank. The activated foils are transferred to a NaI well chamber for gamma-ray spectroscopy and activity measurement. Since PBS treats in layers, the switching time between layers is used to correct for the decay of the activated foils and the relative dose per layer is assumed to be proportional to the neutron fluence per layer. MATLAB code was developed to incorporate the layer delivery and switching time into a calculation of foil activity, which is then used to determine the neutron energy fluence from tabulated foil activation energy thresholds.1. Diffenderfer et. al., Med. Phys., 38(11) 2011.« less

Radioprotection of 1,2-dimethylhydrazine-initiated colon cancer in rats using low-dose γ rays by modulating multidrug resistance-1, cytokeratin 20, and β-catenin expression.

PubMed

Nabil, H M; Hassan, B N; Tohamy, A A; Waaer, H F; Abdel Moneim, A E

2016-03-01

Ionizing radiation is a widely used therapy for solid tumors. However, high-dose ionizing radiation causes apoptosis, transforms normal cells into tumor cells, and impairs immune functions, leading to the defects in the removal of damaged or tumor cells. In contrast, low-dose radiation has been reported to exert various beneficial effects in cells. This experimental study investigated the effect of γ rays at low dose on the development of colorectal tumor in a 1,2-dimethylhydrazine (DMH)-induced colon cancer. Colorectal tumor model was induced in Wistar rats by subcutaneous injection of DMH (20 mg/kg) once a week for 15 weeks. Starting from zero day of DMH injection, a single low dose of whole-body γ irradiation of 0.5 Gy/week was applied to the rats. A significant reduction in lipid peroxidation, nitric oxide, and elevation in the glutathione content and antioxidant enzyme activity (superoxide dismutase and catalase) were observed after γ irradiation comparing with DMH group. Moreover, γ ray reduced the expressions of multidrug resistance 1 (MDR1), β-catenin, and cytokeratin 20 (CK20) those increased in DMH-treated rats. However, survivin did not change with γ ray treatment. A histopathological examination of the DMH-injected rats revealed ulcerative colitis, dysplasia, anaplasia, and hyperchromasia. An improvement in the histopathological picture was seen in the colon of rats exposed to γ rays. In conclusion, the present results showed that low-dose γ ray significantly inhibited DMH-induced colon carcinogenesis in rats by modulating CK20, MDR1, and β-catenin expression but not survivin expression. © The Author(s) 2015.

NASA GeneLab Project: Bridging Space Radiation Omics with Ground Studies.

PubMed

Beheshti, Afshin; Miller, Jack; Kidane, Yared; Berrios, Daniel; Gebre, Samrawit G; Costes, Sylvain V

2018-06-01

Accurate assessment of risks of long-term space missions is critical for human space exploration. It is essential to have a detailed understanding of the biological effects on humans living and working in deep space. Ionizing radiation from galactic cosmic rays (GCR) is a major health risk factor for astronauts on extended missions outside the protective effects of the Earth's magnetic field. Currently, there are gaps in our knowledge of the health risks associated with chronic low-dose, low-dose-rate ionizing radiation, specifically ions associated with high (H) atomic number (Z) and energy (E). The NASA GeneLab project ( https://genelab.nasa.gov/ ) aims to provide a detailed library of omics datasets associated with biological samples exposed to HZE. The GeneLab Data System (GLDS) includes datasets from both spaceflight and ground-based studies, a majority of which involve exposure to ionizing radiation. In addition to detailed information on radiation exposure for ground-based studies, GeneLab is adding detailed, curated dosimetry information for spaceflight experiments. GeneLab is the first comprehensive omics database for space-related research from which an investigator can generate hypotheses to direct future experiments, utilizing both ground and space biological radiation data. The GLDS is continually expanding as omics-related data are generated by the space life sciences community. Here we provide a brief summary of the space radiation-related data available at GeneLab.

The Effect of Low-Dose Ionizing Radiation on Stem Cell Biology: A Contribution to Radiation Risk.

PubMed

Squillaro, Tiziana; Galano, Giovanni; De Rosa, Roberto; Peluso, Gianfranco; Galderisi, Umberto

2018-04-17

Exposure to high levels of ionizing radiation (IR) (>0.5Gy), negatively affect health. but, less is known about the effects of low dose IR (LDIR) but recent, evidence suggests that it may have profound effects on cellular functions. We are commonly exposed to LDIR over natural background levels from numerous sources: people may be exposed to low dose IR for medical diagnosis and therapy, air travel, illegal IR waste dumpsites or by occupational exposures in the nuclear and medical sectors. Stem cells reside for long periods of time in our bodies, and this increases the possibility that they may be accumulate genotoxic damage derived from extrinsic LDIR or intrinsic sources (such as DNA replication). In this review we provide an overview of LDIR effects on biology of stem cell compartments. The principal findings and issues reported in the scientific literature are discussed in order to present the current understanding of the LDIR exposure risk, and assess whether it may impact human health. We first consider the general biological consequences of LDIR exposure. Following this, we discuss the effects of LDIR on stem cells as discovered through in vitro and in vivo studies. This article is protected by copyright. All rights reserved. © 2018 AlphaMed Press.

A Systems Approach to Evaluating Ionizing Radiation: Six Focus Areas to Improve Quality, Efficiency, and Patient Safety

PubMed Central

Mower, Laura; Bushe, Chris

2015-01-01

Abstract: Ionizing radiation is an essential component of the care process. However, providers and patients may not be fully aware of the risks involved, the level of ionizing radiation delivered with various procedures, or the potential for harm through incidental overexposure or cumulative dose. Recent high-profile incidents demonstrating the devastating short-term consequences of radiation overexposure have drawn attention to these risks, but applicable solutions are lacking. Although various recommendations and guidelines have been proposed, organizational variability challenges providers to identify their own practical solutions. To identify potential failure modes and develop solutions to preserve patient safety within a large, national healthcare system, we assembled a multidisciplinary team to conduct a comprehensive analysis of practices surrounding the delivery of ionizing radiation. Workgroups were developed to analyze existing culture, processes, and technology to identify deficiencies and propose solutions. Six focus areas were identified: competency and certification; equipment; monitoring and auditing; education; clinical pathways; and communication and marketing. This manuscript summarizes this comprehensive, multidisciplinary, and systemic analysis of risk and provides examples to illustrate how these focus areas can be used to improve the use of ionizing radiation. The proposed solutions, once fully implemented, may advance patient safety and care. PMID:26042626

Quantitative prediction of ionization effect on human skin permeability.

PubMed

Baba, Hiromi; Ueno, Yusuke; Hashida, Mitsuru; Yamashita, Fumiyoshi

2017-04-30

Although skin permeability of an active ingredient can be severely affected by its ionization in a dose solution, most of the existing prediction models cannot predict such impacts. To provide reliable predictors, we curated a novel large dataset of in vitro human skin permeability coefficients for 322 entries comprising chemically diverse permeants whose ionization fractions can be calculated. Subsequently, we generated thousands of computational descriptors, including LogD (octanol-water distribution coefficient at a specific pH), and analyzed the dataset using nonlinear support vector regression (SVR) and Gaussian process regression (GPR) combined with greedy descriptor selection. The SVR model was slightly superior to the GPR model, with externally validated squared correlation coefficient, root mean square error, and mean absolute error values of 0.94, 0.29, and 0.21, respectively. These models indicate that Log D is effective for a comprehensive prediction of ionization effects on skin permeability. In addition, the proposed models satisfied the statistical criteria endorsed in recent model validation studies. These models can evaluate virtually generated compounds at any pH; therefore, they can be used for high-throughput evaluations of numerous active ingredients and optimization of their skin permeability with respect to permeant ionization. Copyright © 2017 Elsevier B.V. All rights reserved.

Fault handling schemes in electronic systems with specific application to radiation tolerance and VLSI design

NASA Technical Reports Server (NTRS)

Attia, John Okyere

1993-01-01

Naturally occurring space radiation particles can produce transient and permanent changes in the electrical properties of electronic devices and systems. In this work, the transient radiation effects on DRAM and CMOS SRAM were considered. In addition, the effect of total ionizing dose radiation of the switching times of CMOS logic gates were investigated. Effects of transient radiation on the column and cell of MOS dynamic memory cell was simulated using SPICE. It was found that the critical charge of the bitline was higher than that of the cell. In addition, the critical charge of the combined cell-bitline was found to be dependent on the gate voltage of the access transistor. In addition, the effect of total ionizing dose radiation on the switching times of CMOS logic gate was obtained. The results of this work indicate that, the rise time of CMOS logic gates increases, while the fall time decreases with an increase in total ionizing dose radiation. Also, by increasing the size of the P-channel transistor with respect to that of the N-channel transistor, the propagation delay of CMOS logic gate can be made to decrease with, or be independent of an increase in total ionizing dose radiation. Furthermore, a method was developed for replacing polysilicon feedback resistance of SRAMs with a switched capacitor network. A switched capacitor SRAM was implemented using MOS Technology. The critical change of the switched capacitor SRAM has a very large critical charge. The results of this work indicate that switched capacitor SRAM is a viable alternative to SRAM with polysilicon feedback resistance.

Effects of Low-Dose Ionizing Radiation and Menadione, an Inducer of Oxidative Stress, Alone and in Combination in a Vertebrate Embryo Model

PubMed Central

Bladen, Catherine L.; Kozlowski, David J.; Dynan, William S.

2014-01-01

Prior work has established the zebrafish embryo as an in vivo model for studying the biological effects of exposure to low doses of ionizing radiation. One of the known effects of radiation is to elevate the levels of reactive oxygen species (ROS) in tissue. However, ROS are also produced as byproducts of normal metabolism and, regardless of origin, ROS produce similar chemical damage to DNA. Here we use the zebrafish embryo model to investigate whether the effects of low-dose (0–1.5 Gy) radiation and endogenous ROS are mechanistically distinct. We increased levels of endogenous ROS by exposure to low concentrations of the quinone drug, menadione. Imaging studies in live embryos showed that exposure to 3 μM or higher concentrations of menadione dramatically increased ROS levels. This treatment was associated with a growth delay and morphologic abnormalities, which were partially or fully reversible. By contrast, exposure to low doses of ionizing radiation had no discernable effects on overall growth or morphology, although, there was an increase in TUNEL-positive apoptotic cells, consistent with the results of prior studies. Further studies showed that the combined effect of radiation and menadione exposure are greater than with either agent alone, and that attenuation of the expression of Ku80, a gene important for repair of radiation-induced DNA damage, had only a slight effect on menadione sensitivity. Together, results suggest that ionizing radiation and menadione affect the embryo by distinct mechanisms. PMID:23092554

Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

DOE PAGES

Castillo, Hugo; Smith, Geoffrey B.

2017-02-14

All organisms on earth grow under the influence of a natural and relatively constant dose of ionizing radiation referred to as background radiation, and so cells have different mechanisms to prevent the accumulation of damage caused by its different components. However, current knowledge of the deleterious effects of radiation on cells is based on the exposure to acute and high or to chronic, above background doses of radiation and therefore is not appropriate to explain the cellular and biochemical mechanisms that cells employ to sense and respond to chronic below-background levels. Studies at below-background radiation doses can provide insight intomore » the biological role of radiation, as suggested by several examples of what appears to be a stress response in cells grown at doses that range from 10 to 79 times lower than background. Here, we discuss some of the technical constraints to shield cells from radiation to below-background levels, as well as different approaches used to detect and measure responses to such unusual environmental conditions. Then, we present data from Shewanella oneidensis and Deinococcus radiodurans experiments that show how two taxonomically distant bacterial species sense and respond to unnaturally low levels of radiation. Finally, in brief, we grew S. oneidensis and D. radiodurans in liquid culture at dose rates of 72.05 (control) and 0.91 (treatment) nGy hr -1 (including radon) for up to 72 h and measured cell density and the expression of stress-related genes. Our results suggest that a stress response is triggered in the absence of normal levels of radiation.« less

Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castillo, Hugo; Smith, Geoffrey B.

All organisms on earth grow under the influence of a natural and relatively constant dose of ionizing radiation referred to as background radiation, and so cells have different mechanisms to prevent the accumulation of damage caused by its different components. However, current knowledge of the deleterious effects of radiation on cells is based on the exposure to acute and high or to chronic, above background doses of radiation and therefore is not appropriate to explain the cellular and biochemical mechanisms that cells employ to sense and respond to chronic below-background levels. Studies at below-background radiation doses can provide insight intomore » the biological role of radiation, as suggested by several examples of what appears to be a stress response in cells grown at doses that range from 10 to 79 times lower than background. Here, we discuss some of the technical constraints to shield cells from radiation to below-background levels, as well as different approaches used to detect and measure responses to such unusual environmental conditions. Then, we present data from Shewanella oneidensis and Deinococcus radiodurans experiments that show how two taxonomically distant bacterial species sense and respond to unnaturally low levels of radiation. Finally, in brief, we grew S. oneidensis and D. radiodurans in liquid culture at dose rates of 72.05 (control) and 0.91 (treatment) nGy hr -1 (including radon) for up to 72 h and measured cell density and the expression of stress-related genes. Our results suggest that a stress response is triggered in the absence of normal levels of radiation.« less

Final report for project "Effects of Low-Dose Irradiation on NFkB Signaling Networks and Mitochondria"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woloschak, Gayle E; Grdina, David; Li, Jian-Jian

Low dose ionizing radiation effects are difficult to study in human population because of the numerous confounding factors such as genetic and lifestyle differences. Research in mammalian model systems and in vitro is generally used in order to overcome this difficulty. In this program project three projects have joined together to investigate effects of low doses of ionizing radiation. These are doses at and below 10 cGy of low linear energy transfer ionizing radiation such as X-ray and gamma rays. This project was focused on cellular signaling associated with nuclear factor kappa B (NFkB) and mitochondria - subcellular organelles criticalmore » for cell aging and aging-like changes induced by ionizing radiation. In addition to cells in culture this project utilized animal tissues accumulated in a radiation biology tissue archive housed at Northwestern University (http://janus.northwestern.edu/janus2/index.php). Major trust of Project 1 was to gather all of the DoE sponsored irradiated animal (mouse, rat and dog) data and tissues under one roof and investigate mitochondrial DNA changes and micro RNA changes in these samples. Through comparison of different samples we were trying to delineate mitochondrial DNA quantity alterations and micro RNA expression differences associated with different doses and dose rates of radiation. Historic animal irradiation experiments sponsored by DoE were done in several national laboratories and universities between 1950’s and 1990’s; while these experiments were closed data and tissues were released to Project 1. Project 2 used cells in culture to investigate effects that low doses or radiation have on NFκB and its target genes manganese superoxide dismutase (MnSOD) and genes involved in cell cycle: Cyclins (B1 and D1) and cyclin dependent kinases (CDKs). Project 3 used cells in culture such as “normal” human cells (breast epithelial cell line MCF10A cells and skin keratinocyte cells HK18) and mouse embryo fibroblast (mef) cells to focus on role of NFkB protein and several other proteins such as survivin (BIRC5) in radiation dependent regulation of tumor necrosis factor alpha (TNFα) and its downstream signaling.« less

Dosimetric properties of a proton beamline dedicated to the treatment of ocular disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slopsema, R. L., E-mail: rslopsema@floridaproton.org; Mamalui, M.; Yeung, D.

2014-01-15

Purpose: A commercial proton eyeline has been developed to treat ocular disease. Radiotherapy of intraocular lesions (e.g., uveal melanoma, age-related macular degeneration) requires sharp dose gradients to avoid critical structures like the macula and optic disc. A high dose rate is needed to limit patient gazing times during delivery of large fractional dose. Dose delivery needs to be accurate and predictable, not in the least because current treatment planning algorithms have limited dose modeling capabilities. The purpose of this paper is to determine the dosimetric properties of a new proton eyeline. These properties are compared to those of existing systemsmore » and evaluated in the context of the specific clinical requirements of ocular treatments. Methods: The eyeline is part of a high-energy, cyclotron-based proton therapy system. The energy at the entrance of the eyeline is 105 MeV. A range modulator (RM) wheel generates the spread-out Bragg peak, while a variable range shifter system adjusts the range and spreads the beam laterally. The range can be adjusted from 0.5 up to 3.4 g/cm{sup 2}; the modulation width can be varied in steps of 0.3 g/cm{sup 2} or less. Maximum field diameter is 2.5 cm. All fields can be delivered with a dose rate of 30 Gy/min or more. The eyeline is calibrated according to the IAEA TRS-398 protocol using a cylindrical ionization chamber. Depth dose distributions and dose/MU are measured with a parallel-plate ionization chamber; lateral profiles with radiochromic film. The dose/MU is modeled as a function of range, modulation width, and instantaneous MU rate with fit parameters determined per option (RM wheel). Results: The distal fall-off of the spread-out Bragg peak is 0.3 g/cm{sup 2}, larger than for most existing systems. The lateral penumbra varies between 0.9 and 1.4 mm, except for fully modulated fields that have a larger penumbra at skin. The source-to-axis distance is found to be 169 cm. The dose/MU shows a strong dependence on range (up to 4%/mm). A linear increase in dose/MU as a function of instantaneous MU rate is observed. The dose/MU model describes the measurements with an accuracy of ±2%. Neutron dose is found to be 146 ± 102 μSv/Gy at the contralateral eye and 19 ± 13 μSv/Gy at the chest. Conclusions: Measurements show the proton eyeline meets the requirements to effectively treat ocular disease.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slopsema, R. L., E-mail: rslopsema@floridaproton.org; Mamalui, M.; Yeung, D.

Purpose: A commercial proton eyeline has been developed to treat ocular disease. Radiotherapy of intraocular lesions (e.g., uveal melanoma, age-related macular degeneration) requires sharp dose gradients to avoid critical structures like the macula and optic disc. A high dose rate is needed to limit patient gazing times during delivery of large fractional dose. Dose delivery needs to be accurate and predictable, not in the least because current treatment planning algorithms have limited dose modeling capabilities. The purpose of this paper is to determine the dosimetric properties of a new proton eyeline. These properties are compared to those of existing systemsmore » and evaluated in the context of the specific clinical requirements of ocular treatments. Methods: The eyeline is part of a high-energy, cyclotron-based proton therapy system. The energy at the entrance of the eyeline is 105 MeV. A range modulator (RM) wheel generates the spread-out Bragg peak, while a variable range shifter system adjusts the range and spreads the beam laterally. The range can be adjusted from 0.5 up to 3.4 g/cm{sup 2}; the modulation width can be varied in steps of 0.3 g/cm{sup 2} or less. Maximum field diameter is 2.5 cm. All fields can be delivered with a dose rate of 30 Gy/min or more. The eyeline is calibrated according to the IAEA TRS-398 protocol using a cylindrical ionization chamber. Depth dose distributions and dose/MU are measured with a parallel-plate ionization chamber; lateral profiles with radiochromic film. The dose/MU is modeled as a function of range, modulation width, and instantaneous MU rate with fit parameters determined per option (RM wheel). Results: The distal fall-off of the spread-out Bragg peak is 0.3 g/cm{sup 2}, larger than for most existing systems. The lateral penumbra varies between 0.9 and 1.4 mm, except for fully modulated fields that have a larger penumbra at skin. The source-to-axis distance is found to be 169 cm. The dose/MU shows a strong dependence on range (up to 4%/mm). A linear increase in dose/MU as a function of instantaneous MU rate is observed. The dose/MU model describes the measurements with an accuracy of ±2%. Neutron dose is found to be 146 ± 102 μSv/Gy at the contralateral eye and 19 ± 13 μSv/Gy at the chest. Conclusions: Measurements show the proton eyeline meets the requirements to effectively treat ocular disease.« less

Radiation dose delivery verification in the treatment of carcinoma-cervix

NASA Astrophysics Data System (ADS)

Shrotriya, D.; Kumar, S.; Srivastava, R. N. L.

2015-06-01

The accurate dose delivery to the clinical target volume in radiotherapy can be affected by various pelvic tissues heterogeneities. An in-house heterogeneous woman pelvic phantom was designed and used to verify the consistency and computational capability of treatment planning system of radiation dose delivery in the treatment of cancer cervix. Oncentra 3D-TPS with collapsed cone convolution (CCC) dose calculation algorithm was used to generate AP/PA and box field technique plan. the radiation dose was delivered by Primus Linac (Siemens make) employing high energy 15 MV photon beam by isocenter technique. A PTW make, 0.125cc ionization chamber was used for direct measurements at various reference points in cervix, bladder and rectum. The study revealed that maximum variation between computed and measured dose at cervix reference point was 1% in both the techniques and 3% and 4% variation in AP/PA field and 5% and 4.5% in box technique at bladder and rectum points respectively.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cebe, M; Pacaci, P; Mabhouti, H

Purpose: In this study, the two available calculation algorithms of the Varian Eclipse treatment planning system(TPS), the electron Monte Carlo(eMC) and General Gaussian Pencil Beam(GGPB) algorithms were used to compare measured and calculated peripheral dose distribution of electron beams. Methods: Peripheral dose measurements were carried out for 6, 9, 12, 15, 18 and 22 MeV electron beams of Varian Triology machine using parallel plate ionization chamber and EBT3 films in the slab phantom. Measurements were performed for 6×6, 10×10 and 25×25cm{sup 2} cone sizes at dmax of each energy up to 20cm beyond the field edges. Using the same filmmore » batch, the net OD to dose calibration curve was obtained for each energy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution measured using parallel plate ionization chamber and EBT3 film and calculated by eMC and GGPB algorithms were compared. The measured and calculated data were then compared to find which algorithm calculates peripheral dose distribution more accurately. Results: The agreement between measurement and eMC was better than GGPB. The TPS underestimated the out of field doses. The difference between measured and calculated doses increase with the cone size. The largest deviation between calculated and parallel plate ionization chamber measured dose is less than 4.93% for eMC, but it can increase up to 7.51% for GGPB. For film measurement, the minimum gamma analysis passing rates between measured and calculated dose distributions were 98.2% and 92.7% for eMC and GGPB respectively for all field sizes and energies. Conclusion: Our results show that the Monte Carlo algorithm for electron planning in Eclipse is more accurate than previous algorithms for peripheral dose distributions. It must be emphasized that the use of GGPB for planning large field treatments with 6 MeV could lead to inaccuracies of clinical significance.« less

Modification and characterization of a high-energy photon irradiation facility using nitrogen-16

NASA Astrophysics Data System (ADS)

Roy, Tapash Kumar

This work involves fabrication and characterization of a reactor source of high energy (˜7 MeV) nitrogen-16 photons for application in evaluation of dosimetric responses of personnel devices and portable instruments. The N-16 source has been established by continuously flowing coolant water from the core of a 1 MW research reactor through a cylindrical thin walled aluminium chamber. Dose measurements have been made at selected distances of interest along the depth axis both for with and without a near-air equilibrium wall of polymethyl methacrylate (PMMA) in place. Photon dose and exposure measurements were done using condenser-R ionization chambers with sufficiently thick walls to yield an approximate transient charged particle equilibrium (TCPE) condition. Field areal uniformity was defined using large area Kodak Readypack RP films along with lead foil radiators. Dosimetric quantities of interest include skin dose, eye (lens) dose, and 1 cm deep dose. Measurements were made at selected depths of 7, 300, and 1000 mg cm-2 for specific evaluation of these respective quantities. Photon spectral analysis was performed with a NaI(Tl) scintillation spectrometry system. Additionally, beta radiation measurements, and evaluation of neutron dose contributions to the radiation field were completed.

Enhancement of radiation cytotoxicity by gold nanoparticles in MCF-7 breast cancer cell lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosli, Nur Shafawati binti; Rahman, Azhar Abdul; Aziz, Azlan Abdul

2015-04-24

Therapy combined with metallic nanoparticles is a new way to treat cancer, in which gold nanoparticles (AuNPs) are injected through intravenous administration and bound to tumor sites. Radiotherapy aims to deliver a high therapeutic dose of ionizing radiation to the tumor without exceeding normal tissue tolerance. The use of AuNPs which is a high-atomic-number (Z) material in radiotherapy will provide a high probability for photon interaction by photoelectric effect. These provide advantages in terms of radiation dose enhancement. The high linear energy transfer and short range of photoelectric interaction products (photoelectrons, characteristic x-rays, Auger electrons) produce localized dose enhancement ofmore » the tumor. In this work, breast cancer cell lines (MCF-7) are seeded in the 96-well plate and were treated with 13 nm AuNPs before they were irradiated with 6 MV and 10 MV photon beam from a medical linear accelerator at various radiation doses. To validate the enhanced killing effect, both with and without AuNPs MCF-7 cells is irradiated simultaneously. By comparison, the results show that AuNPs significantly enhance cancer killing.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfe, B.; Wallis, L.R.

This paper has a dual purpose. On the one hand, congratulations are in order; the 25th Hanford Life Sciences Symposium celebrates four decades of important research at Hanford. This research has helped provide a better understanding of ionizing radiation effects on man and his environment. Researchers at Hanford and those at other locations can take pride in the fact that today we know more about the major characteristics and potential health effects of ionizing radiation than we do for any other biological hazard. Ionizing radiation's present mysteries, important as they are, involve subtleties that are difficult to explore in detailmore » because the effects are so small relative to other health effects. It will also be a pleasure to add our tribute, along with many others, to Herb Parker, a friend, colleague, and pioneer in the radiation protection field. Building on the work of early pioneers such as Herb and those who have and will follow in their footsteps, we will develop an even broader understanding--an understanding that will clarify the effects of low-level radiation exposure, an area of knowledge about which sound explanations and predictions elude us today. The second purpose of this paper is to remind those in the radiation protection field that they have been less than successful in one of their most important tasks--that of effective communication. The task is not an easy one because the content of the message depends upon the dose. At high doses, above 1 Sv, where the deleterious effects of radiation are predictable, there is agreement on the message that must be delivered to the public: avoid it. There is no confusion in the public sector about this message. At the much lower doses resulting from beneficial activities, the message we must convey to the public is different.« less

Total Dose Effects on Single Event Transients in Linear Bipolar Systems

NASA Technical Reports Server (NTRS)

Buchner, Stephen; McMorrow, Dale; Bernard, Muriel; Roche, Nicholas; Dusseau, Laurent

2008-01-01

Single Event Transients (SETs) originating in linear bipolar integrated circuits are known to undermine the reliability of electronic systems operating in the radiation environment of space. Ionizing particle radiation produces a variety of SETs in linear bipolar circuits. The extent to which these SETs threaten system reliability depends on both their shapes (amplitude and width) and their threshold energies. In general, SETs with large amplitudes and widths are the most likely to propagate from a bipolar circuit's output through a subsystem. The danger these SET pose is that, if they become latched in a follow-on circuit, they could cause an erroneous system response. Long-term exposure of linear bipolar circuits to particle radiation produces total ionizing dose (TID) and/or displacement damage dose (DDD) effects that are characterized by a gradual degradation in some of the circuit's electrical parameters. For example, an operational amplifier's gain-bandwidth product is reduced by exposure to ionizing radiation, and it is this reduction that contributes to the distortion of the SET shapes. In this paper, we compare SETs produced in a pristine LM124 operational amplifier with those produced in one exposed to ionizing radiation for three different operating configurations - voltage follower (VF), inverter with gain (IWG), and non-inverter with gain (NIWG). Each configuration produces a unique set of transient shapes that change following exposure to ionizing radiation. An important finding is that the changes depend on operating configuration; some SETs decrease in amplitude, some remain relatively unchanged, some become narrower and some become broader.

Radiation Tests of the Extravehicular Mobility Unit Space Suit for the International Space Station Using Energetic Protons. Chapter 3

NASA Technical Reports Server (NTRS)

Zeitlin, C.; Heilbronn, L.; Miller, J.; Shavers, M.

2003-01-01

Measurements using silicon detectors to characterize the radiation transmitted through the EMU space suit and a human phantom have been performed using 155 and 250 MeV proton beams at LLUMC. The beams simulate radiation encountered in space, where trapped protons having kinetic energies on the order of 100 MeV are copious. Protons with 100 MeV kinetic energy and above can penetrate many centimeters of water or other light materials, so that astronauts exposed to such energetic particles will receive doses to their internal organs. This dose can be enhanced or reduced by shielding - either from the space suit or the self-shielding of the body - but minimization of the risk depends on details of the incident particle flux (in particular the energy spectrum) and on the dose responses of the various critical organs. Data were taken to characterize the beams and to calibrate the detectors using the beam in a treatment room at LLUPTF, in preparation for an experiment with the same beams incident on detectors placed in a human phantom within the EMU suit. Nuclear interactions of high-energy protons in various materials produce a small flux of highly ionizing, low-energy secondary radiation. Secondaries are of interest for their biological effects, since they cause doses and especially dose-equivalents to increase relative to the values expected simply from ionization energy loss along the Bragg curve. Because many secondaries have very short ranges, they are best measured in passive track detectors such as CR-39. The silicon detector data presented here are intended to supplement the CR-39 data in regions where silicon has greater sensitivity, in particular the portion of the LET spectrum below 5 keV/micron. The results obtained in this study suggest that optimizing the radiation shielding properties of space suits is a formidable task. The naive assumption that adding mass can reduce risk is not supported by the data, which show that reducing the dose delivered at or near the skin by low-energy particles may increase the dose delivered by energetic particles to points deeper in the body.

Compendium of Current Single Event Effects for Candidate Spacecraft Electronics for NASA

NASA Technical Reports Server (NTRS)

O'Bryan, Martha V.; Label, Kenneth A.; Chen, Dakai; Campola, Michael J.; Casey, Megan C.; Lauenstein, Jean-Marie; Pellish, Jonathan A.; Ladbury, Raymond L.; Berg, Melanie D.

2015-01-01

NASA spacecraft are subjected to a harsh space environment that includes exposure to various types of ionizing radiation. The performance of electronic devices in a space radiation environment are often limited by their susceptibility to single event effects (SEE). Ground-based testing is used to evaluate candidate spacecraft electronics to determine risk to spaceflight applications. Interpreting the results of radiation testing of complex devices is and adequate understanding of the test condition is critical. Studies discussed herein were undertaken to establish the application-specific sensitivities of candidate spacecraft and emerging electronic devices to single-event upset (SEU), single-event latchup (SEL), single-event gate rupture (SEGR), single-event burnout (SEB), and single-event transient (SET). For total ionizing dose (TID) and displacement damage dose (DDD) results, see a companion paper submitted to the 2015 Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space Radiation Effects Conference (NSREC) Radiation Effects Data Workshop (REDW) entitled "compendium of Current Total Ionizing Dose and Displacement Damage for Candidate Spacecraft Electronics for NASA by M. Campola, et al.

Occupational Exposure of the Eye Lens in Interventional Procedures: How to Assess and Manage Radiation Dose.

PubMed

Ciraj-Bjelac, Olivera; Carinou, Eleftheria; Ferrari, Paolo; Gingaume, Merce; Merce, Marta Sans; O'Connor, Una

2016-11-01

Occupational exposure from interventional x-ray procedures is one of the areas in which increased eye lens exposure may occur. Accurate dosimetry is an important element to investigate the correlation of observed radiation effects with radiation dose, to verify the compliance with regulatory dose limits, and to optimize radiation protection practice. The objective of this work is to review eye lens dose levels in clinical practice that may occur from the use of ionizing radiation. The use of a dedicated eye lens dosimeter is the recommended methodology; however, in practice it cannot always be easily implemented. Alternatively, the eye lens dose could be assessed from measurements of other dosimetric quantities or other indirect parameters, such as patient dose. The practical implementation of monitoring eye lens doses and the use of adequate protective equipment still remains a challenge. The use of lead glasses with a good fit to the face, appropriate lateral coverage, and/or ceiling-suspended screens is recommended in workplaces with potential high eye lens doses. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Jha, Pradeep K.; Jha, Rakhi; Gupta, B. L.; Guha, Sujoy K.

2010-05-01

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

Compact modeling of total ionizing dose and aging effects in MOS technologies

DOE PAGES

Esqueda, Ivan S.; Barnaby, Hugh J.; King, Michael Patrick

2015-06-18

This paper presents a physics-based compact modeling approach that incorporates the impact of total ionizing dose (TID) and stress-induced defects into simulations of metal-oxide-semiconductor (MOS) devices and integrated circuits (ICs). This approach utilizes calculations of surface potential (ψs) to capture the charge contribution from oxide trapped charge and interface traps and to describe their impact on MOS electrostatics and device operating characteristics as a function of ionizing radiation exposure and aging effects. The modeling approach is demonstrated for bulk and silicon-on-insulator (SOI) MOS device. The formulation is verified using TCAD simulations and through the comparison of model calculations and experimentalmore » I-V characteristics from irradiated devices. The presented approach is suitable for modeling TID and aging effects in advanced MOS devices and ICs.« less

Decomposition of 2,4-dichlorophenoxyacetic acid by ozonation, ionizing radiation as well as ozonation combined with ionizing radiation

NASA Astrophysics Data System (ADS)

Drzewicz, Przemyslaw; Trojanowicz, Marek; Zona, Robert; Solar, Sonja; Gehringer, Peter

2004-03-01

Electron beam (EB), ozone (O 3) and the combination EB/O 3 were used to study the oxidative decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) in local tap water. Using an EB treatment, a dose of 10 kGy was required for complete 2,4-D degradation, and a 90% conversion of organic chlorine into chloride ions. Using additionally 1.33 mmol dm -3 O 3 during irradiation, the same result was achieved with a dose of 2.7 kGy. The yields of products acetate and formate were almost doubled by the combined EB/O 3 treatment, compared to those obtained with the same dose by EB irradiation. Gamma radiolysis showed that the degradation dose was proportional to the initial concentration of 2,4-D in the range of 50-2260 μmol dm -3.

Comparative proteomic analysis of rice after seed ground simulated radiation and spaceflight explains the radiation effects of space environment

NASA Astrophysics Data System (ADS)

Wang, Wei; Shi, Jinming; Liang, Shujian; Lei, Huang; Shenyi, Zhang; Sun, Yeqing

In previous work, we compared the proteomic profiles of rice plants growing after seed space-flights with ground controls by two-dimensional difference gel electrophoresis (2-D DIGE) and found that the protein expression profiles were changed after seed space environment exposures. Spaceflight represents a complex environmental condition in which several interacting factors such as cosmic radiation, microgravity and space magnetic fields are involved. Rice seed is in the process of dormant of plant development, showing high resistance against stresses, so the highly ionizing radiation (HZE) in space is considered as main factor causing biological effects to seeds. To further investigate the radiation effects of space environment, we performed on-ground simulated HZE particle radiation and compared between the proteomes of seed irra-diated plants and seed spaceflight (20th recoverable satellite) plants from the same rice variety. Space ionization shows low-dose but high energy particle effects, for searching the particle effects, ground radiations with the same low-dose (2mGy) but different liner energy transfer (LET) values (13.3KeV/µm-C, 30KeV/µm-C, 31KeV/µm-Ne, 62.2KeV/µm-C, 500Kev/µm-Fe) were performed; using 2-D DIGE coupled with clustering and principle component analysis (PCA) for data process and comparison, we found that the holistic protein expression patterns of plants irradiated by LET-62.2KeV/µm carbon particles were most similar to spaceflight. In addition, although space environment presents a low-dose radiation (0.177 mGy/day on the satellite), the equivalent simulated radiation dose effects should still be evaluated: radiations of LET-62.2KeV/µm carbon particles with different cumulative doses (2mGy, 20mGy, 200mGy, 2000mGy) were further carried out and resulted that the 2mGy radiation still shared most similar proteomic profiles with spaceflight, confirming the low-dose effects of space radiation. Therefore, in the protein expression level, ground simulation method could be utilized to simu-late the space radiation biological effects and such a comparative proteomic work might explain both energy and dose effects of space radiation environment.

Site-Specific Phosphorylation of Ikaros Induced by Low-Dose Ionizing Radiation Regulates Cell Cycle Progression of B Lymphoblast Through CK2 and AKT Activation.

PubMed

Cho, Seong-Jun; Kang, Hana; Kim, Min Young; Lee, Jung Eun; Kim, Sung Jin; Nam, Seon Young; Kim, Ji Young; Kim, Hee Sun; Pyo, Suhkneung; Yang, Kwang Hee

2016-04-01

To determine how low-dose ionizing radiation (LDIR) regulates B lympho-proliferation and its molecular mechanism related with Ikaros, transcription factor. Splenocytes and IM-9 cells were uniformly irradiated with various doses of a (137)Cs γ-source, and cell proliferation was analyzed. To determine the LDIR-specific phosphorylation of Ikaros, immunoprecipitation and Western blot analysis were performed. To investigate the physiologic function of LDIR-mediatied Ikaros phosphorylation, Ikaros mutants at phosphorylation sites were generated, and cell cycle analysis was performed. First, we found that LDIR enhances B lymphoblast proliferation in an Ikaros-dependent manner. Moreover, we found that LDIR elevates the phosphorylation level of Ikaros protein. Interestingly, we showed that CK2 and AKT are involved in LDIR-induced Ikaros phosphorylation and capable of regulating DNA binding activity of Ikaros via specific phosphorylation. Finally, we identified LDIR-specific Ikaros phosphorylation sites at S391/S393 and showed that the Ikaros phosphorylations at these sites control Ikaros's ability to regulate G1/S cell cycle progression. Low-dose ionizing radiation specifically phosphorylates Ikaros protein at Ser 391/393 residues to regulate cell cycle progression in B lymphoblast. Copyright © 2016 Elsevier Inc. All rights reserved.

Epidemiologic Study of One Million American Workers and Military Veterans Exposed to Ionizing Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boice, John D.

2015-02-27

A pilot study was completed demonstrating the feasibility of conducting an epidemiologic study assessing cancer and other disease mortality among nearly one million US veterans and workers exposed to ionizing radiation, a population 10 times larger than atomic bomb survivor study with high statistical power to evaluate low dose rate effects. Among the groups enumerated and/or studied were: (1) 194,000 Department of Energy Uranium Workers; (2) 6,700 Rocketdyne Radiation Workers; (3) 7,000 Mound Radiation Workers; (4) 156,000 DOE Plutonium Workers; (5) 212,000 Nuclear Power Plant Workers; (6) 130,000 Industrial Radiography Workers; (7) 1.7 million Medical Workers and (8) 135,000 Atomicmore » Veterans.« less

SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uehara, K; Ogata, T; Nakayama, M

2015-06-15

Purpose: In commissioning of volumetric modulated arc therapy (VMAT), it is necessary to evaluate the beam characteristics of various dose rate settings with potential to use. The aim of this study is to evaluate the beam characteristics of flattened and flattening filter free (FFF) including low dose rate setting. Methods: We used a Varian TrueBeam with Millennium 120 MLC. Both 6 and 10 MV beams with or without flattening filter were used for this study. To evaluate low-dose rate FFF beams, specially-designed leaf sequence files control out-of-field MLC leaf pair at constant dose rate ranging from 80 to 400 MU/min.more » For dose rate from 80 MU/min to the maximum usable value of all energies, beam output were measured using ionization chamber (CC04, IBA). The ionization chamber was inserted into water equivalent phantom (RT3000-New, R-tech), and the phantom was set with SAD of 100cm. The beam profiles were performed using the 2D diode array (Profiler2, Sun Nuclear). The SSD was set to 90cm and a combined 30cmx30cmx9cm phantom which consisted of solid water slabs was put on the device. All measurement were made using 100MU irradiation for 10cmx10cm jaw-defined field size with a gantry angle of 0°. Results: In all energies, the dose rate dependences with beam output and variation coefficient were within 0.2% and 0.07%, respectively. The flatness and symmetry exhibited small variations (flatness ≤0.1 point and symmetry≤0.3 point at absolute difference). Conclusion: We had studied the characteristics of flattened and FFF beam over the 80 MU/min. Our results indicated that the beam output and profiles of FFF of TrueBeam linac were highly stable at low dose rate setting.« less

SU-E-T-223: Computed Radiography Dose Measurements of External Radiotherapy Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aberle, C; Kapsch, R

2015-06-15

Purpose: To obtain quantitative, two-dimensional dose measurements of external radiotherapy beams with a computed radiography (CR) system and to derive volume correction factors for ionization chambers in small fields. Methods: A commercial Kodak ACR2000i CR system with Kodak Flexible Phosphor Screen HR storage foils was used. Suitable measurement conditions and procedures were established. Several corrections were derived, including image fading, length-scale corrections and long-term stability corrections. Dose calibration curves were obtained for cobalt, 4 MV, 8 MV and 25 MV photons, and for 10 MeV, 15 MeV and 18 MeV electrons in a water phantom. Inherent measurement inhomogeneities were studiedmore » as well as directional dependence of the response. Finally, 2D scans with ionization chambers were directly compared to CR measurements, and volume correction factors were derived. Results: Dose calibration curves (0.01 Gy to 7 Gy) were obtained for multiple photon and electron beam qualities. For each beam quality, the calibration curves can be described by a single fit equation over the whole dose range. The energy dependence of the dose response was determined. The length scale on the images was adjusted scan-by-scan, typically by 2 percent horizontally and by 3 percent vertically. The remaining inhomogeneities after the system’s standard calibration procedure were corrected for. After correction, the homogeneity is on the order of a few percent. The storage foils can be rotated by up to 30 degrees without a significant effect on the measured signal. First results on the determination of volume correction factors were obtained. Conclusion: With CR, quantitative, two-dimensional dose measurements with a high spatial resolution (sub-mm) can be obtained over a large dose range. In order to make use of these advantages, several calibrations, corrections and supporting measurements are needed. This work was funded by the European Metrology Research Programme (EMRP) project HLT09 MetrExtRT Metrology for Radiotherapy using Complex Radiation Fields.« less

Monitoring Space Radiation Hazards with the Responsive Environmental Assessment Commercially Hosted (REACH) Project

NASA Astrophysics Data System (ADS)

Mazur, J. E.; Guild, T. B.; Crain, W.; Crain, S.; Holker, D.; Quintana, S.; O'Brien, T. P., III; Kelly, M. A.; Barnes, R. J.; Sotirelis, T.

2017-12-01

The Responsive Environmental Assessment Commercial Hosting (REACH) project uses radiation dosimeters on a commercial satellite constellation in low Earth orbit to provide unprecedented spatial and time sampling of space weather radiation hazards. The spatial and time scales of natural space radiation environments coupled with constraints for the hosting accommodation drove the instrumentation requirements and the plan for the final orbital constellation. The project has delivered a total of thirty two radiation dosimeter instruments for launch with each instrument containing two dosimeters with different passive shielding and electronic thresholds to address proton-induced single-event effects, vehicle charging, and total ionizing dose. There are two REACH instruments currently operating with four more planned for launch by the time of the 2017 meeting. Our aim is to field a long-lived system of highly-capable radiation detectors to monitor the hazards of single-event effects, total ionizing dose, and spacecraft charging with maximized spatial coverage and with minimal time latency. We combined a robust detection technology with a commercial satellite hosting to produce a new demonstration for satellite situational awareness and for other engineering and science applications.

Method and apparatus for measuring low currents in capacitance devices

DOEpatents

Kopp, M.K.; Manning, F.W.; Guerrant, G.C.

1986-06-04

A method and apparatus for measuring subnanoampere currents in capacitance devices is reported. The method is based on a comparison of the voltages developed across the capacitance device with that of a reference capacitor in which the current is adjusted by means of a variable current source to produce a stable voltage difference. The current varying means of the variable current source is calibrated to provide a read out of the measured current. Current gain may be provided by using a reference capacitor which is larger than the device capacitance with a corresponding increase in current supplied through the reference capacitor. The gain is then the ratio of the reference capacitance to the device capacitance. In one illustrated embodiment, the invention makes possible a new type of ionizing radiation dose-rate monitor where dose-rate is measured by discharging a reference capacitor with a variable current source at the same rate that radiation is discharging an ionization chamber. The invention eliminates high-megohm resistors and low current ammeters used in low-current measuring instruments.

Could ionizing radiation forestall cauliflower ear?

PubMed

Hwang, K; Kim, C W; Lee, S I; Park, I S; Kim, W C; Loh, J J

2001-02-01

Repeated trauma to the ear very often results in "cauliflower ear." Many methods have been suggested to prevent an injured ear from demonstrating a cauliflowerlike deformity. The principles of treatment are evacuation of the hematoma, control of the reaccumulation of fluid, and maintenance of the cartilage contour. The authors studied the effect of ionizing radiation on deformed rabbit ears induced by repeated trauma. Twenty ears (10 rabbits) were used in the experiment. The animals were divided into four groups (control, preradiation, low dose, and high dose). Hematoma was produced by pounding the lateral side of the auricle 10 times with a 50-g weight at a height of 15 cm. The thickness of the injured and uninjured sites was measured, and histological analysis was performed for each group. The thickness of the ears of the irradiated groups was significantly less than the control group. The authors think that radiation treatment of repeatedly injured ears could prevent ear deformity, and could possibly be an adjunctive form of management of cauliflower ear in addition to hematoma evacuation and compression therapy.

Three-dimensional Čerenkov tomography of energy deposition from ionizing radiation beams.

PubMed

Glaser, Adam K; Voigt, William H A; Davis, Scott C; Zhang, Rongxiao; Gladstone, David J; Pogue, Brian W

2013-03-01

Since its discovery during the 1930s the Čerenkov effect (light emission from charged particles traveling faster than the local speed of light in a dielectric medium) has been paramount in the development of high-energy physics research. The ability of the emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, to our knowledge, all applications of the process to date have focused on the identification of particles themselves, rather than their effect upon the surroundings through which they travel. Here we explore a novel application of the Čerenkov effect for the recovery of the spatial distribution of ionizing radiation energy deposition in a medium and apply it to the issue of dose determination in medical physics. By capturing multiple projection images of the Čerenkov light induced by a medical linear accelerator x-ray photon beam, we demonstrate the successful three-dimensional tomographic reconstruction of the imparted dose distribution.

Feasibility of using glass-bead thermoluminescent dosimeters for radiotherapy treatment plan verification.

PubMed

Jafari, Shakardokht M; Jordan, Tom J; Distefano, Gail; Bradley, David A; Spyrou, Nicholas M; Nisbet, Andrew; Clark, Catharine H

2015-01-01

To investigate the feasibility of using glass beads as novel thermoluminescent dosemeters (TLDs) for radiotherapy treatment plan verification. Commercially available glass beads with a size of 1-mm thickness and 2-mm diameter were characterized as TLDs. Five clinical treatment plans including a conventional larynx, a conformal prostate, an intensity-modulated radiotherapy (IMRT) prostate and two stereotactic body radiation therapy (SBRT) lung plans were transferred onto a CT scan of a water-equivalent phantom (Solid Water(®), Gammex, Middleton, WI) and the dose distribution recalculated. The number of monitor units was maintained from the clinical plan and delivered accordingly. The doses determined by the glass beads were compared with those measured by a graphite-walled ionization chamber, and the respective expected doses were determined by the treatment-planning system (TPS) calculation. The mean percentage difference between measured dose with the glass beads and TPS was found to be 0.3%, -0.1%, 0.4%, 1.8% and 1.7% for the conventional larynx, conformal prostate, IMRT prostate and each of the SBRT delivery techniques, respectively. The percentage difference between measured dose with the ionization chamber and glass bead was found to be -1.2%, -1.4%, -0.1%, -0.9% and 2.4% for the above-mentioned plans, respectively. The results of measured doses with the glass beads and ionization chamber in comparison with expected doses from the TPS were analysed using a two-sided paired t-test, and there was no significant difference at p < 0.05. It is feasible to use glass-bead TLDs as dosemeters in a range of clinical plan verifications. Commercial glass beads are utilized as low-cost novel TLDs for treatment-plan verification.

Evaluation of awareness on radiation protection and knowledge about radiological examinations in healthcare professionals who use ionized radiation at work.

PubMed

Yurt, Ayşegül; Cavuşoğlu, Berrin; Günay, Türkan

2014-06-01

In this study, we evaluated the knowledge and perception and mitigation of hazards involved in radiological examinations, focusing on healthcare personnel who are not in radiation-related occupations, but who use ionising radiation as a part of their work. A questionnaire was applied to physicians, nurses, technicians and other staff working in different clinics that use radiation in their work, in order to evaluate their knowledge levels about ionizing radiation and their awareness about radiation doses resulting from radiological examinations. The statistical comparisons between the groups were analyzed with the Kruskal Wallis test using the SPSS program. Ninety two participants took part in the study. Their level of knowledge about ionizing radiation and doses in radiological examinations were found to be very weak. The number of correct answers of physicians, nurses, medical technicians and other personnel groups were 15.7±3.7, 13.0±4.0, 10.1±2.9 and 11.8±4.0, respectively. In the statistical comparison between the groups, the level of knowledge of physicians was found to be significantly higher than the level of the other groups (p=0.005). The present study demonstrated that general knowledge in relation to radiation, radiation protection, health risks and doses used for radiological applications are insufficient among health professions using with ionizing radiation in their work.

The Ionizing Radiation Environment on the Moon

NASA Technical Reports Server (NTRS)

Adams, J. H., Jr.; Bhattacharya, M.; Lin, Zi-Wei; Pendleton, G.

2006-01-01

The ionizing radiation environment on the moon that contributes to the radiation hazard for astronauts consists of galactic cosmic rays, solar energetic particles and albedo particles from the lunar surface. We will present calculations of the absorbed dose and the dose equivalent to various organs in this environment during quiet times and during large solar particle events. We will evaluate the contribution of solar particles other than protons and the contributions of the various forms of albedo. We will use the results to determine which particle fluxes must be known in order to estimate the radiation hazard.

Inter-Individual Variability in Human Response to Low-Dose Ionizing Radiation, Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocke, David

2016-08-01

In order to investigate inter-individual variability in response to low-dose ionizing radiation, we are working with three models, 1) in-vivo irradiated human skin, for which we have a realistic model, but with few subjects, all from a previous project, 2) ex-vivo irradiated human skin, for which we also have a realistic model, though with the limitations involved in keeping skin pieces alive in media, and 3) MatTek EpiDermFT skin plugs, which provides a more realistic model than cell lines, which is more controllable than human samples.

A case control study of multiple myeloma at four nuclear facilities.

PubMed

Wing, S; Richardson, D; Wolf, S; Mihlan, G; Crawford-Brown, D; Wood, J

2000-04-01

Reported elevations of multiple myeloma among nuclear workers exposed to external penetrating ionizing radiation, based on small numbers of cases, prompted this multi-facility study of workers at US Department of Energy facilities. Ninety-eight multiple myeloma deaths and 391 age-matched controls were selected from the combined roster of 115,143 workers hired before 1979 at Hanford, Los Alamos National Laboratory, Oak Ridge National Laboratory, and the Savannah River site. These workers were followed for vital status through 1990 (1986 for Hanford). Demographic, work history, and occupational exposure data were derived from personnel, occupational medicine, industrial hygiene, and health physics records. Exposure-disease associations were evaluated using conditional logistic regression. Cases were disproportionately African American, male, and hired prior to 1948. Lifetime cumulative whole body ionizing radiation dose was not associated with multiple myeloma, however, there was a significant effect of age at exposure, with positive associations between multiple myeloma and doses received at older ages. Dose response associations increased in magnitude with exposure age (from 40 to 50) and lag assumption (from 5 to 15 years), while a likelihood ratio goodness of fit test reached the highest value for cumulative doses received at ages above 45 with a 5-year lag (X2=5.43,1 df; relative risk = 6.9% per 10 mSv). Dose response associations persisted with adjustment for potential confounders. Multiple myeloma was associated with low level whole body penetrating ionizing radiation doses at older ages. The exposure age effect is at odds with interpretations of A-bomb survivor studies but in agreement with several studies of cancer among nuclear workers.

Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET.

PubMed

Vlachopoulou, Vassiliki; Malatara, Georgia; Delis, Harry; Theodorou, Kiki; Kardamakis, Dimitrios; Panayiotakis, George

2010-11-28

To study the peripheral dose (PD) from high-energy photon beams in radiotherapy using the metal oxide semiconductor field effect transistor (MOSFET) dose verification system. The radiation dose absorbed by the MOSFET detector was calculated taking into account the manufacturer's Correction Factor, the Calibration Factor and the threshold voltage shift. PD measurements were carried out for three different field sizes (5 cm × 5 cm, 10 cm × 10 cm and 15 cm × 15 cm) and for various depths with the source to surface distance set at 100 cm. Dose measurements were realized on the central axis and then at distances (1 to 18 cm) parallel to the edge of the field, and were expressed as the percentage PD (% PD) with respect to the maximum dose (d(max)). The accuracy of the results was evaluated with respect to a calibrated 0.3 cm(3) ionization chamber. The reproducibility was expressed in terms of standard deviation (s) and coefficient of variation. % PD is higher near the phantom surface and drops to a minimum at the depth of d(max), and then tends to become constant with depth. Internal scatter radiation is the predominant source of PD and the depth dependence is determined by the attenuation of the primary photons. Closer to the field edge, where internal scatter from the phantom dominates, the % PD increases with depth because the ratio of the scatter to primary increases with depth. A few centimeters away from the field, where collimator scatter and leakage dominate, the % PD decreases with depth, due to attenuation by the water. The % PD decreases almost exponentially with the increase of distance from the field edge. The decrease of the % PD is more than 60% and can reach up to 90% as the measurement point departs from the edge of the field. For a given distance, the % PD is significantly higher for larger field sizes, due to the increase of the scattering volume. Finally, the measured PD obtained with MOSFET is higher than that obtained with an ionization chamber with percentage differences being from 0.6% to 34.0%. However, when normalized to the central d(max) this difference is less than 1%. The MOSFET system, in the early stage of its life, has a dose measurement reproducibility of within 1.8%, 2.7%, 8.9% and 13.6% for 22.8, 11.3, 3.5 and 1.3 cGy dose assessments, respectively. In the late stage of MOSFET life the corresponding values change to 1.5%, 4.8%, 11.1% and 29.9% for 21.8, 2.9, 1.6 and 1.0 cGy, respectively. Comparative results acquired with the MOSFET and with an ionization chamber show fair agreement, supporting the suitability of this measurement for clinical in vivo dosimetry.

Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET

PubMed Central

Vlachopoulou, Vassiliki; Malatara, Georgia; Delis, Harry; Theodorou, Kiki; Kardamakis, Dimitrios; Panayiotakis, George

2010-01-01

AIM: To study the peripheral dose (PD) from high-energy photon beams in radiotherapy using the metal oxide semiconductor field effect transistor (MOSFET) dose verification system. METHODS: The radiation dose absorbed by the MOSFET detector was calculated taking into account the manufacturer’s Correction Factor, the Calibration Factor and the threshold voltage shift. PD measurements were carried out for three different field sizes (5 cm × 5 cm, 10 cm × 10 cm and 15 cm × 15 cm) and for various depths with the source to surface distance set at 100 cm. Dose measurements were realized on the central axis and then at distances (1 to 18 cm) parallel to the edge of the field, and were expressed as the percentage PD (% PD) with respect to the maximum dose (dmax). The accuracy of the results was evaluated with respect to a calibrated 0.3 cm3 ionization chamber. The reproducibility was expressed in terms of standard deviation (s) and coefficient of variation. RESULTS: % PD is higher near the phantom surface and drops to a minimum at the depth of dmax, and then tends to become constant with depth. Internal scatter radiation is the predominant source of PD and the depth dependence is determined by the attenuation of the primary photons. Closer to the field edge, where internal scatter from the phantom dominates, the % PD increases with depth because the ratio of the scatter to primary increases with depth. A few centimeters away from the field, where collimator scatter and leakage dominate, the % PD decreases with depth, due to attenuation by the water. The % PD decreases almost exponentially with the increase of distance from the field edge. The decrease of the % PD is more than 60% and can reach up to 90% as the measurement point departs from the edge of the field. For a given distance, the % PD is significantly higher for larger field sizes, due to the increase of the scattering volume. Finally, the measured PD obtained with MOSFET is higher than that obtained with an ionization chamber with percentage differences being from 0.6% to 34.0%. However, when normalized to the central dmax this difference is less than 1%. The MOSFET system, in the early stage of its life, has a dose measurement reproducibility of within 1.8%, 2.7%, 8.9% and 13.6% for 22.8, 11.3, 3.5 and 1.3 cGy dose assessments, respectively. In the late stage of MOSFET life the corresponding values change to 1.5%, 4.8%, 11.1% and 29.9% for 21.8, 2.9, 1.6 and 1.0 cGy, respectively. CONCLUSION: Comparative results acquired with the MOSFET and with an ionization chamber show fair agreement, supporting the suitability of this measurement for clinical in vivo dosimetry. PMID:21179311

Thermoradiation inactivation of naturally occurring organisms in soil

NASA Technical Reports Server (NTRS)

Reynolds, M. C.; Lindell, K. F.; David, T. J.

1973-01-01

Samples of soil collected from Kennedy Space Center near spacecraft assembly facilities were found to contain microorganisms very resistant to conventional sterilization techniques. The inactivation behavior of the naturally occurring spores in soil was investigated using dry heat and ionizing radiation, first separately, then in combination. Dry heat inactivation rates of spores were determined for 105 and 125 C. Radiation inactivation rates were determined for dose rates of 660 and 76 krad/hr at 25 C. Simultaneous combinations of heat and radiation were then investigated at 105, 110, 115, 120, and 125 C. Combined treatment was found to be highly synergistic requiring greatly reduced radiation doses to accomplish sterilization.

Ionizing radiation improves glioma-specific targeting of superparamagnetic iron oxide nanoparticles conjugated with cmHsp70.1 monoclonal antibodies (SPION-cmHsp70.1)

NASA Astrophysics Data System (ADS)

Shevtsov, Maxim A.; Nikolaev, Boris P.; Ryzhov, Vyacheslav A.; Yakovleva, Ludmila Y.; Marchenko, Yaroslav Y.; Parr, Marina A.; Rolich, Valerij I.; Mikhrina, Anastasiya L.; Dobrodumov, Anatolii V.; Pitkin, Emil; Multhoff, Gabriele

2015-12-01

The stress-inducible 72 kDa heat shock protein Hsp70 is known to be expressed on the membrane of highly aggressive tumor cells including high-grade gliomas, but not on the corresponding normal cells. Membrane Hsp70 (mHsp70) is rapidly internalized into tumor cells and thus targeting of mHsp70 might provide a promising strategy for theranostics. Superparamagnetic iron oxide nanoparticles (SPIONs) are contrast negative agents that are used for the detection of tumors with MRI. Herein, we conjugated the Hsp70-specific antibody (cmHsp70.1) which is known to recognize mHsp70 to superparamagnetic iron nanoparticles to assess tumor-specific targeting before and after ionizing irradiation. In vitro experiments demonstrated the selectivity of SPION-cmHsp70.1 conjugates to free and mHsp70 in different tumor cell types (C6 glioblastoma, K562 leukemia, HeLa cervix carcinoma) in a dose-dependent manner. High-resolution MRI (11 T) on T2-weighted images showed the retention of the conjugates in the C6 glioma model. Accumulation of SPION-cmHsp70.1 nanoparticles in the glioma resulted in a nearly 2-fold drop of values in comparison to non-conjugated SPIONs. Biodistribution analysis using NLR-M2 measurements showed a 7-fold increase in the tumor-to-background (normal brain) uptake ratio of SPION-cmHsp70.1 conjugates in glioma-bearing rats in comparison to SPIONs. This accumulation within Hsp70-positive glioma was further enhanced after a single dose (10 Gy) of ionizing radiation. Elevated accumulation of the magnetic conjugates in the tumor due to radiosensitization proves the combination of radiotherapy and application of Hsp70-targeted agents in brain tumors.The stress-inducible 72 kDa heat shock protein Hsp70 is known to be expressed on the membrane of highly aggressive tumor cells including high-grade gliomas, but not on the corresponding normal cells. Membrane Hsp70 (mHsp70) is rapidly internalized into tumor cells and thus targeting of mHsp70 might provide a promising strategy for theranostics. Superparamagnetic iron oxide nanoparticles (SPIONs) are contrast negative agents that are used for the detection of tumors with MRI. Herein, we conjugated the Hsp70-specific antibody (cmHsp70.1) which is known to recognize mHsp70 to superparamagnetic iron nanoparticles to assess tumor-specific targeting before and after ionizing irradiation. In vitro experiments demonstrated the selectivity of SPION-cmHsp70.1 conjugates to free and mHsp70 in different tumor cell types (C6 glioblastoma, K562 leukemia, HeLa cervix carcinoma) in a dose-dependent manner. High-resolution MRI (11 T) on T2-weighted images showed the retention of the conjugates in the C6 glioma model. Accumulation of SPION-cmHsp70.1 nanoparticles in the glioma resulted in a nearly 2-fold drop of values in comparison to non-conjugated SPIONs. Biodistribution analysis using NLR-M2 measurements showed a 7-fold increase in the tumor-to-background (normal brain) uptake ratio of SPION-cmHsp70.1 conjugates in glioma-bearing rats in comparison to SPIONs. This accumulation within Hsp70-positive glioma was further enhanced after a single dose (10 Gy) of ionizing radiation. Elevated accumulation of the magnetic conjugates in the tumor due to radiosensitization proves the combination of radiotherapy and application of Hsp70-targeted agents in brain tumors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06521f

Liquid Microjunction Surface Sampling Coupled with High-Pressure Liquid Chromatography-Electrospray Ionization-Mass Spectrometry for Analysis of Drugs and Metabolites in Whole-Body Thin Tissue Sections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kertesz, Vilmos; Van Berkel, Gary J

2010-01-01

In this work, a commercially available autosampler was adapted to perform direct liquid microjunction (LMJ) surface sampling followed by a high-pressure liquid chromatography (HPLC) separation of the extract components and detection with electrospray ionization mass spectrometry (ESI-MS). To illustrate the utility of coupling a separation with this direct liquid extraction based surface sampling approach, four different organs (brain, lung, kidney, and liver) from whole-body thin tissue sections of propranolol dosed and control mice were examined. The parent drug was observed in the chromatograms of the surface sampling extracts from all the organs of the dosed mouse examined. In addition, twomore » isomeric phase II metabolites of propranolol (an aliphatic and an aromatic hydroxypropranolol glucuronide) were observed in the chromatograms of the extracts from lung, kidney, and liver. Confirming the presence of one or the other or both of these glucuronides in the extract from the various organs was not possible without the separation. These drug and metabolite data obtained using the LMJ surface sampling/HPLC-MS method and the results achieved by analyzing similar samples by conventional extraction of the tissues and subsequent HPLC-MS analysis were consistent.« less

Survival, DNA Integrity, and Ultrastructural Damage in Antarctic Cryptoendolithic Eukaryotic Microorganisms Exposed to Ionizing Radiation.

PubMed

Pacelli, Claudia; Selbmann, Laura; Zucconi, Laura; Raguse, Marina; Moeller, Ralf; Shuryak, Igor; Onofri, Silvano

2017-02-01

Life dispersal between planets, planetary protection, and the search for biosignatures are main topics in astrobiology. Under the umbrella of the STARLIFE project, three Antarctic endolithic microorganisms, the melanized fungus Cryomyces antarcticus CCFEE 515, a hyaline strain of Umbilicaria sp. (CCFEE 6113, lichenized fungus), and a Stichococcus sp. strain (C45A, green alga), were exposed to high doses of space-relevant gamma radiation ( 60 Co), up to 117.07 kGy. After irradiation survival, DNA integrity and ultrastructural damage were tested. The first was assessed by clonogenic test; viability and dose responses were reasonably described by the linear-quadratic formalism. DNA integrity was evaluated by PCR, and ultrastructural damage was observed by transmission electron microscopy. The most resistant among the tested organisms was C. antarcticus both in terms of colony formation and DNA preservation. Besides, results clearly demonstrate that DNA was well detectable in all the tested organisms even when microorganisms were dead. This high resistance provides support for the use of DNA as a possible biosignature during the next exploration campaigns. Implication in planetary protection and contamination during long-term space travel are put forward. Key Words: Biosignatures-Ionizing radiation-DNA integrity-Eukaryotic microorganisms-Fingerprinting-Mars exploration. Astrobiology 17, 126-135.

Concepts for dose determination in flat-detector CT

NASA Astrophysics Data System (ADS)

Kyriakou, Yiannis; Deak, Paul; Langner, Oliver; Kalender, Willi A.

2008-07-01

Flat-detector computed tomography (FD-CT) scanners provide large irradiation fields of typically 200 mm in the cranio-caudal direction. In consequence, dose assessment according to the current definition of the computed tomography dose index CTDIL=100 mm, where L is the integration length, would demand larger ionization chambers and phantoms which do not appear practical. We investigated the usefulness of the CTDI concept and practical dosimetry approaches for FD-CT by measurements and Monte Carlo (MC) simulations. An MC simulation tool (ImpactMC, VAMP GmbH, Erlangen, Germany) was used to assess the dose characteristics and was calibrated with measurements of air kerma. For validation purposes measurements were performed on an Axiom Artis C-arm system (Siemens Medical Solutions, Forchheim, Germany) equipped with a flat detector of 40 cm × 30 cm. The dose was assessed for 70 kV and 125 kV in cylindrical PMMA phantoms of 160 mm and 320 mm diameter with a varying phantom length from 150 to 900 mm. MC simulation results were compared to the values obtained with a calibrated ionization chambers of 100 mm and 250 mm length and to thermoluminesence (TLD) dose profiles. The MCs simulations were used to calculate the efficiency of the CTDIL determination with respect to the desired CTDI∞. Both the MC simulation results and the dose distributions obtained by MC simulation were in very good agreement with the CTDI measurements and with the reference TLD profiles, respectively, to within 5%. Standard CTDI phantoms which have a z-extent of 150 mm underestimate the dose at the center by up to 55%, whereas a z-extent of >=600 mm appears to be sufficient for FD-CT; the baseline value of the respective profile was within 1% to the reference baseline. As expected, the measurements with ionization chambers of 100 mm and 250 mm offer a limited accuracy, whereas an increased integration length of >=600 mm appeared to be necessary to approximate CTDI∞ in within 1%. MC simulations appear to offer a practical and accurate way of assessing conversion factors for arbitrary dosimetry setups using a standard pencil chamber to provide estimates of CTDI∞. This would eliminate the need for extra-long phantoms and ionization chambers or excessive amounts of TLDs.

SU-F-18C-09: Assessment of OSL Dosimeter Technology in the Validation of a Monte Carlo Radiation Transport Code for CT Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carver, D; Kost, S; Pickens, D

Purpose: To assess the utility of optically stimulated luminescent (OSL) dosimeter technology in calibrating and validating a Monte Carlo radiation transport code for computed tomography (CT). Methods: Exposure data were taken using both a standard CT 100-mm pencil ionization chamber and a series of 150-mm OSL CT dosimeters. Measurements were made at system isocenter in air as well as in standard 16-cm (head) and 32-cm (body) CTDI phantoms at isocenter and at the 12 o'clock positions. Scans were performed on a Philips Brilliance 64 CT scanner for 100 and 120 kVp at 300 mAs with a nominal beam width ofmore » 40 mm. A radiation transport code to simulate the CT scanner conditions was developed using the GEANT4 physics toolkit. The imaging geometry and associated parameters were simulated for each ionization chamber and phantom combination. Simulated absorbed doses were compared to both CTDI{sub 100} values determined from the ion chamber and to CTDI{sub 100} values reported from the OSLs. The dose profiles from each simulation were also compared to the physical OSL dose profiles. Results: CTDI{sub 100} values reported by the ion chamber and OSLs are generally in good agreement (average percent difference of 9%), and provide a suitable way to calibrate doses obtained from simulation to real absorbed doses. Simulated and real CTDI{sub 100} values agree to within 10% or less, and the simulated dose profiles also predict the physical profiles reported by the OSLs. Conclusion: Ionization chambers are generally considered the standard for absolute dose measurements. However, OSL dosimeters may also serve as a useful tool with the significant benefit of also assessing the radiation dose profile. This may offer an advantage to those developing simulations for assessing radiation dosimetry such as verification of spatial dose distribution and beam width.« less

Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors.

PubMed

Karsch, L; Beyreuther, E; Burris-Mog, T; Kraft, S; Richter, C; Zeil, K; Pawelke, J

2012-05-01

The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10(11) Gy∕s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the number of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. The dosimeters are dose rate independent up to 4●10(9) Gy∕s within 2% (OSL and TLD) and up to 15●10(9) Gy∕s within 5% (EBT films). The diamond detectors show strong dose rate dependence. TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.

Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karsch, L.; Beyreuther, E.; Burris-Mog, T.

Purpose: The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10{sup 11} Gy/s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. Methods: The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the numbermore » of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. Results: The dosimeters are dose rate independent up to 410{sup 9} Gy/s within 2% (OSL and TLD) and up to 1510{sup 9} Gy/s within 5% (EBT films). The diamond detectors show strong dose rate dependence. Conclusions: TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.« less

Oncology Patient Perceptions of the Use of Ionizing Radiation in Diagnostic Imaging.

PubMed

Steele, Joseph R; Jones, Aaron K; Clarke, Ryan K; Giordano, Sharon H; Shoemaker, Stowe

2016-07-01

To measure the knowledge of oncology patients regarding use and potential risks of ionizing radiation in diagnostic imaging. A 30-question survey was developed and e-mailed to 48,736 randomly selected patients who had undergone a diagnostic imaging study at a comprehensive cancer center between November 1, 2013 and January 31, 2014. The survey was designed to measure patients' knowledge about use of ionizing radiation in diagnostic imaging and attitudes about radiation. Nonresponse bias was quantified by sending an abbreviated survey to patients who did not respond to the original survey. Of the 48,736 individuals who were sent the initial survey, 9,098 (18.7%) opened it, and 5,462 (11.2%) completed it. A total of 21.7% of respondents reported knowing the definition of ionizing radiation; 35.1% stated correctly that CT used ionizing radiation; and 29.4% stated incorrectly that MRI used ionizing radiation. Many respondents did not understand risks from exposure to diagnostic doses of ionizing radiation: Of 3,139 respondents who believed that an abdominopelvic CT scan carried risk, 1,283 (40.9%) believed sterility was a risk; 669 (21.3%) believed heritable mutations were a risk; 657 (20.9%) believed acute radiation sickness was a risk; and 135 (4.3%) believed cataracts were a risk. Most patients and caregivers do not possess basic knowledge regarding the use of ionizing radiation in oncologic diagnostic imaging. To ensure health literacy and high-quality patient decision making, efforts to educate patients and caregivers should be increased. Such education might begin with information about effects that are not risks of diagnostic imaging. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

SR-TXRF analysis of trace elements in whole blood and heart of rats: effects of irradiation with low and high doses

NASA Astrophysics Data System (ADS)

Mota, C. L.; Pickler, A.; Braz, D.; Barroso, R. C.; Mantuano, A.; Salata, C.; Ferreira-Machado, S. C.; Lau, C. C.; de Almeida, C. E.

2018-04-01

In the last decades, studies showed that the exposure to low doses of ionizing radiation of the body could sense and activate the cell signaling pathways needed to respond to any induced cellular damage. This procedure reduces cell killing compared with a single dose of high radiation dose. Damage to the vasculature can affect the function of most body organs by restricting blood flow and oxygen to tissues; however, the heart and brain are of main concern. The precise relationship between long-term health effects and low-dose exposures remain poorly understood. Biological markers are powerful tools that can be used to determine dose- response relationships and to estimate risk, especially when dealing with, the effects of low dose exposures in humans. These markers should be specific, sensitive, as well as easy and fast to quantify. Various types of biologic specimens are potential candidates for identifying biomarkers but blood has the advantage of being minimally invasive to obtain. In this study, we propose to apply total reflection X-ray fluorescence to quantify possible chemical elemental concentration (sulfer, iron, zinc, potassium and calcium) changes in blood and heart tissues of Wistar rats after total body irradiation with low (0.1 Gy) and high (2.5 Gy) doses. The fluorescence measurements were carried out at the X-ray Fluorescence beamline in the Brazilian Synchrotron Light Laboratory. The results showed that the irradiated animals with low doses have significant alterations in blood and cardiac tissue when compared with animals that received high doses of radiation. Taken together the analysis of all the elements, we can observe that the radiation induced oxidative stress may be the leading cause for alteration of the elemental level in the studied samples.

Clinical in vivo dosimetry using optical fibers.

PubMed

Gripp, S; Haesing, F W; Bueker, H; Schmitt, G

1998-01-01

Discoloring of glass due to ionizing radiation depends on the absorbed dose. The radiation-induced light attenuation in optical fibers may be used as a measure of the dose. In high-energy photon beams (6 MV X rays), a lead-doped silica fiber can be calibrated. A dosimeter based on an optical fiber was developed for applications in radiation therapy. The diameter of the mounted fiber is 0.25 mm, whereas the length depends on the sensitivity required. To demonstrate the applicability, a customized fiber device was used to determine scattered radiation close to the lens of the eye. Measurements were compared with TLDs (LiF) in an anthropomorphic phantom. The comparison with TLD measurements shows good agreement. In contrast to TLD, optical fibers provide immediate dose values, and the readout procedure is much easier. Owing to its small size and diameter, interesting invasive dose measurements are feasible.

Development of methods to monitor ionization modification from dosing vehicles and phospholipids in study samples.

PubMed

Chang, Min; Li, Yongchao; Angeles, Reginald; Khan, Samina; Chen, Lian; Kaplan, Julia; Yang, Liyu

2011-08-01

Two approaches to monitor the matrix effect on ionization in study samples were described. One approach is the addition of multiple reaction monitoring transitions to the bioanalytical methods to monitor the presence of known ionization modification-causing components of the matrix, for example, m/z 184→125 (or m/z 184→184) and m/z 133→89 may be used for phospholipids and polyethylene oxide containing surfactants, respectively. This approach requires no additional equipment and can be readily adapted for most method. The approach detects only the intended interfering compounds and provides little quantitative indication if the matrix effect is within the tolerable range (±15%). The other approach requires the addition of an infusion pump and identifies an appropriate surrogate of the analyte to be infused for the determination of modification on the ionization of the analyte. The second approach detects interferences in the sample regardless of the sources (i.e., dosing vehicle components, co-administrated drugs, their metabolites, phospholipids, plasticizers and endogenous components introduced due to disease stage).

Ionizing radiation test results for an automotive microcontroller on board the Schiaparelli Mars lander

NASA Astrophysics Data System (ADS)

Tapani Nikkanen, Timo; Hieta, Maria; Schmidt, Walter; Genzer, Maria; Haukka, Harri; Harri, Ari-Matti

2016-04-01

The Finnish Meteorological Institute (FMI) has delivered a pressure and a humidity instrument for the ESA ExoMars 2016 Schiaparelli lander mission. Schiaparelli is scheduled to launch towards Mars with the Trace Gas Orbiter on 14th of March 2016. The DREAMS-P (pressure) and DREAMS-H (Humidity) instruments are operated utilizing a novel FMI instrument controller design based on a commercial automotive microcontroller (MCU). A custom qualification program was implemented to qualify the MCU for the relevant launch, cruise and surface operations environment of a Mars lander. Resilience to ionizing radiation is one of the most critical requirements for a digital component operated in space or at planetary bodies. Thus, the expected Total Ionizing Dose accumulated by the MCU was determined and a sample of these components was exposed to a Co-60 gamma radiation source. Part of the samples was powered during the radiation exposure to include the effect of electrical biasing. All of the samples were verified to withstand the expected total ionizing dose with margin. The irradiated test samples were then radiated until failure to determine their ultimate TID.

Evaluation of Data Retention and Imprint Characteristics of FRAMs Under Environmental Stresses for NASA Applications

NASA Technical Reports Server (NTRS)

Sharma, Ashok K.; Teverovsky, Alexander; Dowdy, Terry W.; Hamilton, Brett

2000-01-01

A major reliability issue for all advanced nonvolatile memory (NVM) technology devices including FRAMs (Ferroelectric random access memories) is the data retention characteristics over extended period of time, under environmental stresses and exposure to total ionizing dose (TID) radiation effects. For this testing, 256 Kb FRAMs in 28-pin plastic DIPS, rated for industrial grade temperature range of -40 C to +85 C, were procured. These are two-transistor, two-capacitor (2T-2C) design FRAMs. In addition to data retention characteristics, the parts were also evaluated for imprint failures, which are defined as the failure of cells to change from a "preferred" state, where it has been for a significant period of time to an opposite state (e.g., from 1 to 0, or 0 to 1). These 256 K FRAMs were subjected to scanning acoustic microscopy (C-SAM); 1,000 temperature cycles from -65 C to +150 C; high temperature aging at 150 C, 175 C, and 200 C for 1,000 hours; highly accelerated stress test (HAST) for 500 hours; 1,000 hours of operational life test at 125 C; and total ionizing dose radiation testing. As a preconditioning, 10 K read/write cycles were performed on all devices. Interim electrical measurements were performed throughout this characterization, including special imprint testing and final electrical testing. Some failures were observed during high temperature aging test at 200 C, during HAST testing, and during 1,000 hours of operational life at 125 C. The parts passed 10 Krad exposure, but began showing power supply current increases during the dose increment from 10 Krad to 30 Krad, and at 40 Krad severe data retention and parametric failures were observed. Failures from various environmental group testing are currently being analyzed.

Evaluation of Data Retention and Imprint Characteristics of FRAMs Under Environmental Stresses for NASA Applications

NASA Technical Reports Server (NTRS)

Sharma, Asbok K.; Teverovsky, Alexander; Dowdy, Terry W.; Hamilton, Brett

2002-01-01

A major reliability issue for all advanced nonvolatile memory (NVM) technology devices including FRAMs is the data retention characteristics over extended period of time, under environmental stresses and exposure to total ionizing dose (TID) radiation effects. For this testing, 256 Kb FRAMs in 28-pin plastic DIPS, rated for industrial grade temperature range of -40 C to +85 C, were procured. These are two-transistor, two-capacitor (2T-2C) design FRAMs. In addition to data retention characteristics, the parts were also evaluated for imprint failures, which are defined as the failure of cells to change from a "preferred" state, where it has been for a significant period of time to an opposite state (e.g., from 1 to 0, or 0 to 1). These 256 K FRAMs were subjected to scanning acoustic microscopy (C-SAM); 1,000 temperature cycles from -65 C to +150 C; high temperature aging at 150 C, 175 C, and 200 C for 1,000 hours; highly accelerated stress test (HAST) for 500 hours; 1,000 hours of operational life test at 125 C; and total ionizing dose radiation testing. As a preconditioning, 10 K read/write cycles were performed on all devices. Interim electrical measurements were performed throughout this characterization, including special imprint testing and final electrical testing. Some failures were observed during high temperature aging test at 200 C, during HAST testing, and during 1,000 hours of operational life at 125 C. The parts passed 10 Krad exposure, but began showing power supply current increases during the dose increment from 10 Krad to 30 Krad, and at 40 Krad severe data retention and parametric failures were observed. Failures from various environmental group testing are currently being analyzed.

Estimating the Effects of Astronaut Career Ionizing Radiation Dose Limits on Manned Interplanetary Flight Programs

NASA Technical Reports Server (NTRS)

Koontz, Steven L.; Rojdev, Kristina; Valle, Gerard D.; Zipay, John J.; Atwell, William S.

2013-01-01

The Hybrid Inflatable DSH combined with electric propulsion and high power solar-electric power systems offer a near TRL-now solution to the space radiation crew dose problem that is an inevitable aspect of long term manned interplanetary flight. Spreading program development and launch costs over several years can lead to a spending plan that fits with NASA's current and future budgetary limitations, enabling early manned interplanetary operations with space radiation dose control, in the near future while biomedical research, nuclear electric propulsion and active shielding research and development proceed in parallel. Furthermore, future work should encompass laboratory validation of HZETRN calculations, as previous laboratory investigations have not considered large shielding thicknesses and the calculations presented at these thicknesses are currently performed via extrapolation.

Dose reconstruction for individuals exposed to ionizing radiation using chromosome painting

NASA Technical Reports Server (NTRS)

Lucas, J. N.; Cox, A. B. (Principal Investigator)

1997-01-01

To be most useful, a biomarker for dose reconstruction should employ an end point that is highly quantitative, stable with time and easily measured. Reciprocal translocations have been shown to be a promising biomarker that is linked to both prior exposure and risk, and they can be measured easily and quantitatively using fluorescence in situ hybridization. In contrast to other biomarkers that are available, the frequency of reciprocal translocations in individuals exposed to whole-body radiation is stable with time after exposure, has rather small interindividual variability and can be measured accurately at low levels of exposure. Results from recent studies demonstrate that measurements of reciprocal translocation frequencies, facilitated by chromosome painting, can be used to reconstruct radiation dose for individuals exposed in the distant past.

Radiation-Induced Noncancer Risks in Interventional Cardiology: Optimisation of Procedures and Staff and Patient Dose Reduction

PubMed Central

Khairuddin Md Yusof, Ahmad

2013-01-01

Concerns about ionizing radiation during interventional cardiology have been increased in recent years as a result of rapid growth in interventional procedure volumes and the high radiation doses associated with some procedures. Noncancer radiation risks to cardiologists and medical staff in terms of radiation-induced cataracts and skin injuries for patients appear clear potential consequences of interventional cardiology procedures, while radiation-induced potential risk of developing cardiovascular effects remains less clear. This paper provides an overview of the evidence-based reviews of concerns about noncancer risks of radiation exposure in interventional cardiology. Strategies commonly undertaken to reduce radiation doses to both medical staff and patients during interventional cardiology procedures are discussed; optimisation of interventional cardiology procedures is highlighted. PMID:24027768

Dose reconstruction for individuals exposed to ionizing radiation using chromosome painting.

PubMed

Lucas, J N

1997-11-01

To be most useful, a biomarker for dose reconstruction should employ an end point that is highly quantitative, stable with time and easily measured. Reciprocal translocations have been shown to be a promising biomarker that is linked to both prior exposure and risk, and they can be measured easily and quantitatively using fluorescence in situ hybridization. In contrast to other biomarkers that are available, the frequency of reciprocal translocations in individuals exposed to whole-body radiation is stable with time after exposure, has rather small interindividual variability and can be measured accurately at low levels of exposure. Results from recent studies demonstrate that measurements of reciprocal translocation frequencies, facilitated by chromosome painting, can be used to reconstruct radiation dose for individuals exposed in the distant past.

The Effects of Low Dose Irradiation on Inflammatory Response Proteins in a 3D Reconstituted Human Skin Tissue Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varnum, Susan M.; Springer, David L.; Chaffee, Mary E.

Skin responses to moderate and high doses of ionizing radiation include the induction of DNA repair, apoptosis, and stress response pathways. Additionally, numerous studies indicate that radiation exposure leads to inflammatory responses in skin cells and tissue. However, the inflammatory response of skin tissue to low dose radiation (<10 cGy) is poorly understood. In order to address this, we have utilized a reconstituted human skin tissue model (MatTek EpiDerm FT) and assessed changes in 23 cytokines twenty-four and forty eight hours following treatment of skin with either 3 or 10 cGy low-dose of radiation. Three cytokines, IFN-γ, IL-2, MIP-1α, weremore » significantly altered in response to low dose radiation. In contrast, seven cytokines were significantly altered in response to a high radiation dose of 200 cGy (IL-2, IL-10, IL-13, IFN-γ, MIP-1α, TNF α, and VEGF) or the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (G-CSF, GM-CSF, IL-1α, IL-8, MIP-1α, MIP-1β, RANTES). Additionally, radiation induced inflammation appears to have a distinct cytokine response relative to the non-radiation induced stressor, TPA. Overall, these results indicate that there are subtle changes in the inflammatory protein levels following exposure to low dose radiation and this response is a sub-set of what is seen following a high dose in a human skin tissue model.« less

Comparison of CREME (cosmic-ray effects on microelectronics) model LET (linear energy transfer) spaceflight dosimetry data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Letaw, J.R.; Adams, J.H.

The galactic cosmic radiation (GCR) component of space radiation is the dominant cause of single-event phenomena in microelectronic circuits when Earth's magnetic shielding is low. Spaceflights outside the magnetosphere and in high inclination orbits are examples of such circumstances. In high-inclination orbits, low-energy (high LET) particles are transmitted through the field only at extreme latitudes, but can dominate the orbit-averaged dose. GCR is an important part of the radiation dose to astronauts under the same conditions. As a test of the CREME environmental model and particle transport codes used to estimate single event upsets, we have compiled existing measurements ofmore » HZE doses were compiled where GCR is expected to be important: Apollo 16 and 17, Skylab, Apollo Soyuz Test Project, and Kosmos 782. The LET spectra, due to direct ionization from GCR, for each of these missions has been estimated. The resulting comparisons with data validate the CREME model predictions of high-LET galactic cosmic-ray fluxes to within a factor of two. Some systematic differences between the model and data are identified.« less

Fast method for in-flight estimation of total dose from protons and electrons using RADE Minstrument on JUICE

NASA Astrophysics Data System (ADS)

Hajdas, Wojtek; Mrigakshi, Alankrita; Xiao, Hualin

2017-04-01

The primary concern of the ESA JUICE mission to Jupiter is the harsh particle radiation environment. Ionizing particles introduce radiation damage by total dose effects, displacement damages or single events effects. Therefore, both the total ionizing dose and the displacement damage equivalent fluence must be assessed to alert spacecraft and its payload as well as to quantify radiation levels for the entire mission lifetime. We present a concept and implementations steps for simplified method used to compute in flight a dose rate and total dose caused by protons. We also provide refinement of the method previously developed for electrons. The dose rates values are given for predefined active volumes located behind layers of materials with known thickness. Both methods are based on the electron and proton flux measurements provided by the Electron and Proton Detectors inside the Radiation Hard Electron Monitor (RADEM) located on-board of JUICE. The trade-off between method accuracy and programming limitations for in-flight computations are discussed. More comprehensive and precise dose rate computations based on detailed analysis of all stack detectors will be made during off-line data processing. It will utilize full spectral unfolding from all RADEM detector subsystems.

Potential Treatment of Inflammatory and Proliferative Diseases by Ultra-Low Doses of Ionizing Radiations

PubMed Central

Sanders, Charles L.

2012-01-01

Ultra-low doses and dose- rates of ionizing radiation are effective in preventing disease which suggests that they also may be effective in treating disease. Limited experimental and anecdotal evidence indicates that low radiation doses from radon in mines and spas, thorium-bearing monazite sands and enhanced radioactive uranium ore obtained from a natural geological reactor may be useful in treating many inflammatory conditions and proliferative disorders, including cancer. Optimal therapeutic applications were identified via a literature survey as dose-rates ranging from 7 to 11μGy/hr or 28 to 44 times world average background rates. Rocks from an abandoned uranium mine in Utah were considered for therapeutic application and were examined by γ-ray and laser-induced breakdown fluorescence spectroscopy. The rocks showed the presence of transuranics and fission products with a γ-ray energy profile similar to aged spent uranium nuclear fuel (93% dose due to β particles and 7% due to γ rays). Mud packs of pulverized uranium ore rock dust in sealed plastic bags delivering bag surface β,γ dose-rates of 10–450 μGy/h were used with apparent success to treat several inflammatory and proliferative conditions in humans. PMID:23304108

Carotenoid distribution in wild Japanese tree frogs (Hyla japonica) exposed to ionizing radiation in Fukushima.

PubMed

Giraudeau, Mathieu; Bonzom, Jean-Marc; Ducatez, Simon; Beaugelin-Seiller, Karine; Deviche, Pierre; Lengagne, Thierry; Cavalie, Isabelle; Camilleri, Virginie; Adam-Guillermin, Christelle; McGraw, Kevin J

2018-05-09

The nuclear accident in the Fukushima prefecture released a large amount of artificial radionuclides that might have short- and long-term biological effects on wildlife. Ionizing radiation can be a harmful source of reactive oxygen species, and previous studies have already shown reduced fitness effects in exposed animals in Chernobyl. Due to their potential health benefits, carotenoid pigments might be used by animals to limit detrimental effects of ionizing radiation exposure. Here, we examined concentrations of carotenoids in blood (i.e. a snapshot of levels in circulation), liver (endogenous carotenoid reserves), and the vocal sac skin (sexual signal) in relation to the total radiation dose rates absorbed by individual (TDR from 0.2 to 34 µGy/h) Japanese tree frogs (Hyla japonica). We found high within-site variability of TDRs, but no significant effects of the TDR on tissue carotenoid levels, suggesting that carotenoid distribution in amphibians might be less sensitive to ionizing radiation exposure than in other organisms or that the potential deleterious effects of radiation exposure might be less significant or more difficult to detect in Fukushima than in Chernobyl due to, among other things, differences in the abundance and mixture of each radionuclide.

Ionizing radiation post-curing of objects produced by stereolithography and other methods

DOEpatents

Howell, David H.; Eberle, Claude C.; Janke, Christopher J.

2000-01-01

An object comprised of a curable material and formed by stereolithography or another three-dimensional prototyping method, in which the object has undergone initial curing, is subjected to post-curing by ionizing radiation, such as an electron beam having a predetermined beam output energy, which is applied in a predetermined dosage and at a predetermined dose rate. The post-cured object exhibits a property profile which is superior to that which existed prior to the ionizing radiation post-curing.

A dose-response curve for biodosimetry from a 6 MV electron linear accelerator

PubMed Central

Lemos-Pinto, M.M.P.; Cadena, M.; Santos, N.; Fernandes, T.S.; Borges, E.; Amaral, A.

2015-01-01

Biological dosimetry (biodosimetry) is based on the investigation of radiation-induced biological effects (biomarkers), mainly dicentric chromosomes, in order to correlate them with radiation dose. To interpret the dicentric score in terms of absorbed dose, a calibration curve is needed. Each curve should be constructed with respect to basic physical parameters, such as the type of ionizing radiation characterized by low or high linear energy transfer (LET) and dose rate. This study was designed to obtain dose calibration curves by scoring of dicentric chromosomes in peripheral blood lymphocytes irradiated in vitro with a 6 MV electron linear accelerator (Mevatron M, Siemens, USA). Two software programs, CABAS (Chromosomal Aberration Calculation Software) and Dose Estimate, were used to generate the curve. The two software programs are discussed; the results obtained were compared with each other and with other published low LET radiation curves. Both software programs resulted in identical linear and quadratic terms for the curve presented here, which was in good agreement with published curves for similar radiation quality and dose rates. PMID:26445334

Chernobyl Doses. Volume 1. Analysis of Forest Canopy Radiation Response from Multispectral Imagery and the Relationship to Doses

DTIC Science & Technology

1994-09-01

AD-A284 746 Defense Nuclear Agency Alexandria, VA 22310-3398 DNA-TR-92-37-V1 Chernobyl Doses Volume 1-Analysis of Forest Canopy Radiation Response...REPORT DATE 3. REPORT TYPE AND DATES COVERED 940901 Technical 870929- 930930 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Chernobyl Doses Volume 1-Analysis of...volume of the report Chernobyl Doses presents details of a new, quantitative method for remotely sensing ionizing radiation dose to vegetation

NMR-based Metabolomics Analysis of Liver from C57BL/6 Mouse Exposed to Ionizing Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Xiongjie; Hu, Mary; Zhang, Xu

The health effects of exposing to ionizing radiation are attracting great interest in the space exploration community and patients considering radiotherapy. However, the impact to metabolism after exposure to high dose radiation has not yet been clearly defined in livers. In the present study, 1H nuclear magnetic resonance (NMR) based metabolomics combined with multivariate data analysis are applied to study the changes of metabolism in the liver of C57BL/6 mouse after whole body exposure to either gamma (3.0 and 7.8 Gy) or proton (3.0 Gy) radiation. Principal component analysis (PCA) and orthogonal projection to latent structures analysis (OPLS) are employedmore » for classification and identification of potential biomarkers associated with gamma and proton irradiation. The results show that the radiation exposed groups can be well separated from the control group. At the same radiation dosage, the group exposed to proton radiation is well separated from the group exposed to gamma radiation, indicating different radiation sources induce different alterations based on metabolic profiling. Common to both gamma and proton radiation at the high radiation doses studied in this work, compared with the control groups the concentrations of choline, O-phosphocholine and trimethylamine N-oxide are decreased statistically, while those of glutamine, glutathione, malate, creatinine, phosphate, betaine and 4-hydroxyphenylacetate are statistically and significantly elevated after exposure to radiation. Since these altered metabolites are associated with multiple biological pathways, the changes suggest that the exposure to radiation induce abnormality in multiple biological pathways. In particular, metabolites such as 4-hydroxyphenylacetate, betaine, glutamine, choline and trimethylamine N-oxide may be good candidates of pre-diagnose biomarkers for ionizing radiation in liver.« less

Cumulative effective radiation dose received by blunt trauma patients arriving to a military level I trauma center from point of injury and interhospital transfers.

PubMed

Van Arnem, Kerri A; Supinski, David P; Tucker, Jonathan E; Varney, Shawn

2016-12-01

Trauma patients sustaining blunt injuries are exposed to multiple radiologic studies. Evidence indicates that the risk of cancer from exposure to ionizing radiation rises in direct proportion to the cumulative effective dose (CED) received. The purpose of this study is to quantify the amount of ionizing radiation accumulated when arriving directly from point of injury to San Antonio Military Medical Center (SAMMC), a level I trauma center, compared with those transferred from other facilities. A retrospective record review was conducted from 1st January 2010 through 31st December 2012. The SAMMC trauma registry, electronic medical records, and the digital radiology imaging system were searched for possible candidates. The medical records were then analyzed for sex, age, mechanism of injury, received directly from point of injury (direct group), transfer from another medical facility (transfer group), computed tomographic scans received, dose-length product, CED of radiation, and injury severity score. A diagnostic imaging physicist then calculated the estimated CED each subject received based on the dose-length product of each computed tomographic scan. A total of 300 patients were analyzed, with 150 patients in the direct group and 150 patients in the transfer group. Both groups were similar in age and sex. Patients in the transfer group received a significantly greater CED of radiation compared with the direct group (mean, 37.6 mSv vs 28 mSv; P=.001). The radiation received in the direct group correlates with a lifetime attributable risk (LAR) of 1 in 357 compared with the transfer group with an increase in LAR to 1 in 266. Patients transferred to our facility received a 34% increase in ionizing radiation compared with patients brought directly from the injury scene. This increased dose of ionizing radiation contributes to the LAR of cancer and needs to be considered before repeating imaging studies. III. Published by Elsevier Inc.

Radon Exposure and the Definition of Low Doses-The Problem of Spatial Dose Distribution.

PubMed

Madas, Balázs G

2016-07-01

Investigating the health effects of low doses of ionizing radiation is considered to be one of the most important fields in radiological protection research. Although the definition of low dose given by a dose range seems to be clear, it leaves some open questions. For example, the time frame and the target volume in which absorbed dose is measured have to be defined. While dose rate is considered in the current system of radiological protection, the same cancer risk is associated with all exposures, resulting in a given amount of energy absorbed by a single target cell or distributed among all the target cells of a given organ. However, the biological effects and so the health consequences of these extreme exposure scenarios are unlikely to be the same. Due to the heterogeneous deposition of radon progeny within the lungs, heterogeneous radiation exposure becomes a practical issue in radiological protection. While the macroscopic dose is still within the low dose range, local tissue doses on the order of Grays can be reached in the most exposed parts of the bronchial airways. It can be concluded that progress in low dose research needs not only low dose but also high dose experiments where small parts of a biological sample receive doses on the order of Grays, while the average dose over the whole sample remains low. A narrow interpretation of low dose research might exclude investigations with high relevance to radiological protection. Therefore, studies important to radiological protection should be performed in the frame of low dose research even if the applied doses do not fit in the dose range used for the definition of low doses.

Total ionizing dose effect and damage mechanism on saturation output voltage of charge coupled device

NASA Astrophysics Data System (ADS)

Wen, Lin; Li, Yu-dong; Guo, Qi; Wang, Chao-min

2018-02-01

Total ionizing dose effect is a major threat to space applications of CCD, which leads to the decrease of CCD saturation output voltage and the increase of dark signal. This paper investigated CCD and its readout circuit for experimental samples of different channel width to length ratio of MOSFET, and readout circuit amplifier, and CCD. The irradiation source was 60Co- gamma ray. through testing the parameters degradation of MOSFET and amplifier degradation, the generation and annealing law of irradiation induced defects in MOS single tube are analyzed. Combined with the radiation effect of amplifier and CCD, The correlation of radiation damage of the MOSFET and the readout circuit amplifier and CCD parameter degradation is established. Finally, this paper reveals the physical mechanism of ionizing radiation damage of the readout circuit. The research results provide a scientific basis for the selection of anti-radiation technology and structure optimization of domestic CCD.

Radiation dose reduction in thoracic and lumbar spine instrumentation using navigation based on an intraoperative cone beam CT imaging system: a prospective randomized clinical trial.

PubMed

Pireau, Nathalie; Cordemans, Virginie; Banse, Xavier; Irda, Nadia; Lichtherte, Sébastien; Kaminski, Ludovic

2017-11-01

Spine surgery still remains a challenge for every spine surgeon, aware of the potential serious outcomes of misplaced instrumentation. Though many studies have highlighted that using intraoperative cone beam CT imaging and navigation systems provides higher accuracy than conventional freehand methods for placement of pedicle screws in spine surgery, few studies are concerned about how to reduce radiation exposure for patients with the use of such technology. One of the main focuses of this study is based on the ALARA principle (as low as reasonably achievable). A prospective randomized trial was conducted in the hybrid operating room between December 2015 and December 2016, including 50 patients operated on for posterior instrumented thoracic and/or lumbar spinal fusion. Patients were randomized to intraoperative 3D acquisition high-dose (standard dose) or low-dose protocol, and a total of 216 pedicle screws were analyzed in terms of screw position. Two different methods were used to measure ionizing radiation: the total skin dose (derived from the dose-area product) and the radiation dose evaluated by thermoluminescent dosimeters on the surgical field. According to Gertzbein and Heary classifications, low-dose protocol provided a significant higher accuracy of pedicle screw placement than the high-dose protocol (96.1 versus 92%, respectively). Seven screws (3.2%), all implanted with the high-dose protocol, needed to be revised intraoperatively. The use of low-dose acquisition protocols reduced patient exposure by a factor of five. This study emphasizes the paramount importance of using low-dose protocols for intraoperative cone beam CT imaging coupled with the navigation system, as it at least does not affect the accuracy of pedicle screw placement and irradiates drastically less.

Study of genetic effects of high energy radiations with different ionizing capacities on extracellular phages.

PubMed

Bresler, S E; Kalinin, V L; Kopylova, Y U; Krivisky, A S; Rybchin, V N; Shelegedin, V N

1975-07-01

The inactivating and mutagenic action of high-energy radiations with different ionizing capacities (gamma-rays, protons, alpha-particles and accelerated ions of 12C and 20Ne) was studied by using coliphages lambda11 and SD as subjects. In particular the role of irradiation conditions (broth suspension, pure buffer, dry samples) and of the host functions recA, exrA and polA was investigated. The dose-response curve of induced mutagenesis was studied by measuring the yield of vir mutants in lambda11 and plaque mutants in SD. The following results were obtained. (1) The inactivation kinetics of phages under the action of gamma-rays and protons was first order to a survival of 10(-7). Heavy ions also showed exponential inactivation kinetics to a survival of 10(-4). At higher doses of 20Ne ion bombardment some deviation from one-hit kinetics was observed. For dry samples of phages the dimensions of targets for all types of radiation were approximately proportional to the molecular weights of phage DNA's. For densely ionizing radiation (heavy ions) the inactivating action was 3-5 times weaker than for gamma-rays and protons. (2) Mutagenesis was observed for all types of radiation, but heavy ions were 1-5-2 times less efficient than gamma-rays. For both phages studied the dose-response curve of mutagenesis was non-linear. The dependence on the dose was near to parabolic for lambda11. For SD a plateau or maximum of mutagenesis was observed for the relative number of mutants at a survival of about 10(-4). (3) Host-cell functions recA and exrA were practically indifferent for survival of gamma-irradiated phage lambda11, but indispensable for mutagenesis. Mutation recAI3 abolished induced vir mutations totally and exrA- reduced them significantly. The absence of the function polA had a considerable influence on phage survival, but no effect on vir mutation yield (if compared at the same survival level). (4) In conditions of indirect action of gamma-rays no vir mutations were induced. This is regarded as evidence that the single-strand breaks formed under indirect action conditions cannot serve as pre-mutational damage in DNA.

41 CFR 50-204.20 - Radiation-definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... rad due to particles heavier than protons and with sufficient energy to reach the lens of the eye; (5...) Dose means the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the body. When the provisions in this subpart specify a dose during a period of time, the dose is...

41 CFR 50-204.20 - Radiation-definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... rad due to particles heavier than protons and with sufficient energy to reach the lens of the eye; (5...) Dose means the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the body. When the provisions in this subpart specify a dose during a period of time, the dose is...

41 CFR 50-204.20 - Radiation-definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... rad due to particles heavier than protons and with sufficient energy to reach the lens of the eye; (5...) Dose means the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the body. When the provisions in this subpart specify a dose during a period of time, the dose is...

Two-dimensional silicon-based detectors for ion beam therapy

NASA Astrophysics Data System (ADS)

Martišíková, M.; Granja, C.; Jakůbek, J.; Hartmann, B.; Telsemeyer, J.; Huber, L.; Brons, S.; Pospíšil, S.; Jäkel, O.

2012-02-01

Radiation therapy with ion beams is a highly precise kind of cancer treatment. As ion beams traverse material, the highest ionization density occurs at the end of their path. Due to this Bragg-peak, ion beams enable higher dose conformation to the tumor and increased sparing of the surrounding tissue, in comparison to standard radiation therapy using high energy photons. Ions heavier than protons offer in addition increased biological effectiveness and lower scattering. The Heidelberg Ion Beam Therapy Center (HIT) is a state-of-the-art ion beam therapy facility and the first hospital-based facility in Europe. It provides proton and carbon ion treatments. A synchrotron is used for ion acceleration. For dose delivery to the patient, narrow pencil-like beams are scanned over the target volume.

Radiation Hormesis: Historical Perspective and Implications for Low-Dose Cancer Risk Assessment

PubMed Central

Vaiserman, Alexander M.

2010-01-01

Current guidelines for limiting exposure of humans to ionizing radiation are based on the linear-no-threshold (LNT) hypothesis for radiation carcinogenesis under which cancer risk increases linearly as the radiation dose increases. With the LNT model even a very small dose could cause cancer and the model is used in establishing guidelines for limiting radiation exposure of humans. A slope change at low doses and dose rates is implemented using an empirical dose and dose rate effectiveness factor (DDREF). This imposes usually unacknowledged nonlinearity but not a threshold in the dose-response curve for cancer induction. In contrast, with the hormetic model, low doses of radiation reduce the cancer incidence while it is elevated after high doses. Based on a review of epidemiological and other data for exposure to low radiation doses and dose rates, it was found that the LNT model fails badly. Cancer risk after ordinarily encountered radiation exposure (medical X-rays, natural background radiation, etc.) is much lower than projections based on the LNT model and is often less than the risk for spontaneous cancer (a hormetic response). Understanding the mechanistic basis for hormetic responses will provide new insights about both risks and benefits from low-dose radiation exposure. PMID:20585444

Space Weather Nowcasting of Atmospheric Ionizing Radiation for Aviation Safety

NASA Technical Reports Server (NTRS)

Mertens, Christopher J.; Wilson, John W.; Blattnig, Steve R.; Solomon, Stan C.; Wiltberger, J.; Kunches, Joseph; Kress, Brian T.; Murray, John J.

2007-01-01

There is a growing concern for the health and safety of commercial aircrew and passengers due to their exposure to ionizing radiation with high linear energy transfer (LET), particularly at high latitudes. The International Commission of Radiobiological Protection (ICRP), the EPA, and the FAA consider the crews of commercial aircraft as radiation workers. During solar energetic particle (SEP) events, radiation exposure can exceed annual limits, and the number of serious health effects is expected to be quite high if precautions are not taken. There is a need for a capability to monitor the real-time, global background radiations levels, from galactic cosmic rays (GCR), at commercial airline altitudes and to provide analytical input for airline operations decisions for altering flight paths and altitudes for the mitigation and reduction of radiation exposure levels during a SEP event. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model is new initiative to provide a global, real-time radiation dosimetry package for archiving and assessing the biologically harmful radiation exposure levels at commercial airline altitudes. The NAIRAS model brings to bear the best available suite of Sun-Earth observations and models for simulating the atmospheric ionizing radiation environment. Observations are utilized from ground (neutron monitors), from the atmosphere (the METO analysis), and from space (NASA/ACE and NOAA/GOES). Atmospheric observations provide the overhead shielding information and the ground- and space-based observations provide boundary conditions on the GCR and SEP energy flux distributions for transport and dosimetry simulations. Dose rates are calculated using the parametric AIR (Atmospheric Ionizing Radiation) model and the physics-based HZETRN (High Charge and Energy Transport) code. Empirical models of the near-Earth radiation environment (GCR/SEP energy flux distributions and geomagnetic cut-off rigidity) are benchmarked against the physics-based CMIT (Coupled Magnetosphere- Ionosphere-Thermosphere) and SEP-trajectory models.

Comparison of the IAEA TRS-398 and AAPM TG-51 absorbed dose to water protocols in the dosimetry of high-energy photon and electron beams

NASA Astrophysics Data System (ADS)

Saiful Huq, M.; Andreo, Pedro; Song, Haijun

2001-11-01

The International Atomic Energy Agency (IAEA TRS-398) and the American Association of Physicists in Medicine (AAPM TG-51) have published new protocols for the calibration of radiotherapy beams. These protocols are based on the use of an ionization chamber calibrated in terms of absorbed dose to water in a standards laboratory's reference quality beam. This paper compares the recommendations of the two protocols in two ways: (i) by analysing in detail the differences in the basic data included in the two protocols for photon and electron beam dosimetry and (ii) by performing measurements in clinical photon and electron beams and determining the absorbed dose to water following the recommendations of the two protocols. Measurements were made with two Farmer-type ionization chambers and three plane-parallel ionization chamber types in 6, 18 and 25 MV photon beams and 6, 8, 10, 12, 15 and 18 MeV electron beams. The Farmer-type chambers used were NE 2571 and PTW 30001, and the plane-parallel chambers were a Scanditronix-Wellhöfer NACP and Roos, and a PTW Markus chamber. For photon beams, the measured ratios TG-51/TRS-398 of absorbed dose to water Dw ranged between 0.997 and 1.001, with a mean value of 0.999. The ratios for the beam quality correction factors kQ were found to agree to within about +/-0.2% despite significant differences in the method of beam quality specification for photon beams and in the basic data entering into kQ. For electron beams, dose measurements were made using direct ND,w calibrations of cylindrical and plane-parallel chambers in a 60Co gamma-ray beam, as well as cross-calibrations of plane-parallel chambers in a high-energy electron beam. For the direct ND,w calibrations the ratios TG-51/TRS-398 of absorbed dose to water Dw were found to lie between 0.994 and 1.018 depending upon the chamber and electron beam energy used, with mean values of 0.996, 1.006, and 1.017, respectively, for the cylindrical, well-guarded and not well-guarded plane-parallel chambers. The Dw ratios measured for the cross-calibration procedures varied between 0.993 and 0.997. The largest discrepancies for electron beams between the two protocols arise from the use of different data for the perturbation correction factors pwall and pdis of cylindrical and plane-parallel chambers, all in 60Co. A detailed analysis of the reasons for the discrepancies is made which includes comparing the formalisms, correction factors and the quantities in the two protocols.

Simulation and Comparison of Martian Surface Ionization Radiation

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee Y.; Zeitlin, Cary; Hassler, Donald M.; Cucinotta, Francis A.

2013-01-01

The spectrum of energetic particle radiation and corresponding doses at the surface of Mars is being characterized by the Radiation Assessment Detector (RAD), one of ten science instruments on the Mars Science Laboratory (MSL) Curiosity Rover. The time series of dose rate for the first 300 Sols after landing on Mars on August 6, 2012 is presented here. For the comparison to RAD measurements of dose rate, Martian surface ionization radiation is simulated by utilizing observed space quantities. The GCR primary radiation spectrum is calculated by using the Badhwar-O'Neill 2011 (BO11) galactic cosmic ray (GCR) model, which has been developed by utilizing all balloon and satellite GCR measurements since 1955 and the newer 1997-2012 Advanced Composition Explorer (ACE) measurements. In the BO11 model, solar modulation of the GCR primary radiation spectrum is described in terms of the international smoothed sunspot number and a time delay function. For the transport of the impingent GCR primary radiation through Mars atmosphere, a vertical distribution of atmospheric thickness at each elevation is calculated using the vertical profiles of atmospheric temperature and pressure made by Mars Global Surveyor measurements. At Gale Crater in the southern hemisphere, the seasonal variation of atmospheric thickness is accounted for the daily atmospheric pressure measurements of the MSL Rover Environmental Monitoring Station (REMS) by using low- and high-density models for cool- and warm-season, respectively. The spherically distributed atmospheric distance is traced along the slant path, and the resultant directional shielding by Martian atmosphere is coupled with Curiosity vehicle for dose estimates. We present predictions of dose rate and comparison to the RAD measurements. The simulation agrees to within +/- 20% with the RAD measurements showing clearly the variation of dose rate by heliospheric conditions, and presenting the sensitivity of dose rate by atmospheric pressure, which has been found from the RAD experiments and driven by thermal tides on Martian surface.

Space weather effects measured in atmospheric radiation on aircraft

NASA Astrophysics Data System (ADS)

Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Wieman, S. R.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, L. D.; Mertens, C. J.; Xu, X.; Wiltberger, M. J.; Wiley, S.; Teets, E.; Shea, M. A.; Smart, D. F.; Jones, J. B. L.; Crowley, G.; Azeem, S. I.; Halford, A. J.

2016-12-01

Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Since 2013 Space Environment Technologies (SET) has been conducting observations of the atmospheric radiation environment at aviation altitudes using a small fleet of six instruments. The objective of this work is to improve radiation risk management in air traffic operations. Under the auspices of the Automated Radiation Measurements for Aerospace Safety (ARMAS) and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) projects our team is making dose rate measurements on multiple aircraft flying global routes. Over 174 ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the radiation environment resulting from Galactic Cosmic Rays (GCRs), Solar Energetic Protons (SEPs), and outer radiation belt energetic electrons. The real-time radiation exposure is measured as an absorbed dose rate in silicon and then computed as an ambient dose equivalent rate for reporting dose relevant to radiative-sensitive organs and tissue in units of microsieverts per hour. ARMAS total ionizing absorbed dose is captured on the aircraft, downlinked in real-time, processed on the ground into ambient dose equivalent rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users. Dose rates from flight altitudes up to 56,700 ft. are shown for flights across the planet under a variety of space weather conditions. We discuss several space weather effects on the atmospheric radiation environment, including the levels of GCR background radiation, small SEP events, and possible EMIC wave driven energetic electrons from the outer radiation belt creating "radiation" clouds in the troposphere.

Monte Carlo simulations and benchmark measurements on the response of TE(TE) and Mg(Ar) ionization chambers in photon, electron and neutron beams

NASA Astrophysics Data System (ADS)

Lin, Yi-Chun; Huang, Tseng-Te; Liu, Yuan-Hao; Chen, Wei-Lin; Chen, Yen-Fu; Wu, Shu-Wei; Nievaart, Sander; Jiang, Shiang-Huei

2015-06-01

The paired ionization chambers (ICs) technique is commonly employed to determine neutron and photon doses in radiology or radiotherapy neutron beams, where neutron dose shows very strong dependence on the accuracy of accompanying high energy photon dose. During the dose derivation, it is an important issue to evaluate the photon and electron response functions of two commercially available ionization chambers, denoted as TE(TE) and Mg(Ar), used in our reactor based epithermal neutron beam. Nowadays, most perturbation corrections for accurate dose determination and many treatment planning systems are based on the Monte Carlo technique. We used general purposed Monte Carlo codes, MCNP5, EGSnrc, FLUKA or GEANT4 for benchmark verifications among them and carefully measured values for a precise estimation of chamber current from absorbed dose rate of cavity gas. Also, energy dependent response functions of two chambers were calculated in a parallel beam with mono-energies from 20 keV to 20 MeV photons and electrons by using the optimal simple spherical and detailed IC models. The measurements were performed in the well-defined (a) four primary M-80, M-100, M120 and M150 X-ray calibration fields, (b) primary 60Co calibration beam, (c) 6 MV and 10 MV photon, (d) 6 MeV and 18 MeV electron LINACs in hospital and (e) BNCT clinical trials neutron beam. For the TE(TE) chamber, all codes were almost identical over the whole photon energy range. In the Mg(Ar) chamber, MCNP5 showed lower response than other codes for photon energy region below 0.1 MeV and presented similar response above 0.2 MeV (agreed within 5% in the simple spherical model). With the increase of electron energy, the response difference between MCNP5 and other codes became larger in both chambers. Compared with the measured currents, MCNP5 had the difference from the measurement data within 5% for the 60Co, 6 MV, 10 MV, 6 MeV and 18 MeV LINACs beams. But for the Mg(Ar) chamber, the derivations reached 7.8-16.5% below 120 kVp X-ray beams. In this study, we were especially interested in BNCT doses where low energy photon contribution is less to ignore, MCNP model is recognized as the most suitable to simulate wide photon-electron and neutron energy distributed responses of the paired ICs. Also, MCNP provides the best prediction of BNCT source adjustment by the detector's neutron and photon responses.

Evidence Report: Risk of Radiation Carcinogenesis

NASA Technical Reports Server (NTRS)

Huff, Janice; Carnell, Lisa; Blattnig, Steve; Chappell, Lori; Kerry, George; Lumpkins, Sarah; Simonsen, Lisa; Slaba, Tony; Werneth, Charles

2016-01-01

As noted by Durante and Cucinotta (2008), cancer risk caused by exposure to space radiation is now generally considered a main hindrance to interplanetary travel for the following reasons: large uncertainties are associated with the projected cancer risk estimates; no simple and effective countermeasures are available, and significant uncertainties prevent scientists from determining the effectiveness of countermeasures. Optimizing operational parameters such as the length of space missions, crew selection for age and sex, or applying mitigation measures such as radiation shielding or use of biological countermeasures can be used to reduce risk, but these procedures have inherent limitations and are clouded by uncertainties. Space radiation is comprised of high energy protons, neutrons and high charge (Z) and energy (E) nuclei (HZE). The ionization patterns and resulting biological insults of these particles in molecules, cells, and tissues are distinct from typical terrestrial radiation, which is largely X-rays and gamma-rays, and generally characterized as low linear energy transfer (LET) radiation. Galactic cosmic rays (GCR) are comprised mostly of highly energetic protons with a small component of high charge and energy (HZE) nuclei. Prominent HZE nuclei include He, C, O, Ne, Mg, Si, and Fe. GCR ions have median energies near 1 GeV/n, and energies as high as 10 GeV/n make important contributions to the total exposure. Ionizing radiation is a well known carcinogen on Earth (BEIR 2006). The risks of cancer from X-rays and gamma-rays have been established at doses above 50 mSv (5 rem), although there are important uncertainties and on-going scientific debate about cancer risk at lower doses and at low dose rates (<50 mSv/h). The relationship between the early biological effects of HZE nuclei and the probability of cancer in humans is poorly understood, and it is this missing knowledge that leads to significant uncertainties in projecting cancer risks during space exploration (Cucinotta and Durante 2006; Durante and Cucinotta 2008).

Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors

PubMed Central

Sasaki, Masao S.; Tachibana, Akira; Takeda, Shunichi

2014-01-01

Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the ‘integrate-and-fire’ algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to 239Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation–environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. PMID:24366315

Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors.

PubMed

Sasaki, Masao S; Tachibana, Akira; Takeda, Shunichi

2014-05-01

Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to (239)Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation-environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stelljes, T. S., E-mail: tenzin.s.stelljes@uni-oldenburg.de; Looe, H. K.; Chofor, N.

Purpose: The dosimetric properties of the OCTAVIUS Detector 1500 (OD1500) ionization chamber array (PTW-Freiburg, Freiburg, Germany) have been investigated. A comparative study was carried out with the OCTAVIUS Detector 729 and OCTAVIUS Detector 1000 SRS arrays. Methods: The OD1500 array is an air vented ionization chamber array with 1405 detectors in a 27 × 27 cm{sup 2} measurement area arranged in a checkerboard pattern with a chamber-to-chamber distance of 10 mm in each row. A sampling step width of 5 mm can be achieved by merging two measurements shifted by 5 mm, thus fulfilling the Nyquist theorem for intensity modulatedmore » dose distributions. The stability, linearity, and dose per pulse dependence were investigated using a Semiflex 31013 chamber (PTW-Freiburg, Freiburg, Germany) as a reference detector. The effective depth of measurement was determined by measuring TPR curves with the array and a Roos chamber type 31004 (PTW-Freiburg, Freiburg, Germany). Comparative output factor measurements were performed with the array, the Semiflex 31010 ionization chamber and the Diode 60012 (both PTW-Freiburg, Freiburg, Germany). The energy dependence of the OD1500 was measured by comparing the array’s readings to those of a Semiflex 31010 ionization chamber for varying mean photon energies at the depth of measurement, applying to the Semiflex chamber readings the correction factor k{sub NR} for nonreference conditions. The Gaussian lateral dose response function of a single array detector was determined by searching the convolution kernel suitable to convert the slit beam profiles measured with a Diode 60012 into those measured with the array’s central chamber. An intensity modulated dose distribution measured with the array was verified by comparing a OD1500 measurement to TPS calculations and film measurements. Results: The stability and interchamber sensitivity variation of the OD1500 array were within ±0.2% and ±0.58%, respectively. Dose linearity was within 1% over the range from 5 to 1000 MU. The effective point of measurement of the OD1500 for dose measurements in RW3 phantoms was determined to be (8.7 ± 0.2) mm below its front surface. Output factors showed deviations below 1% for field sizes exceeding 4 × 4 cm{sup 2}. The dose per pulse dependence was smaller than 0.4% for doses per pulse from 0.2 to 1 mGy. The energy dependence of the array did not exceed ±0.9%. The parameter σ of the Gaussian lateral dose response function was determined as σ{sub 6MV} = (2.07 ± 0.02) mm for 6 MV and σ{sub 15MV} = (2.09 ± 0.02) mm for 15 MV. An IMRT verification showed passing rates well above 90% for a local 3 mm/3% criterion. Conclusions: The OD1500 array’s dosimetric properties showed the applicability of the array for clinical dosimetry with the possibility to increase the spatial sampling frequency and the coverage of a dose distribution with the sensitive areas of ionization chambers by merging two measurements.« less

Characterization of a synthetic single crystal diamond detector for dosimetry in spatially fractionated synchrotron x-ray fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Livingstone, Jayde, E-mail: Jayde.Livingstone@sync

Purpose: Modern radiotherapy modalities often use small or nonstandard fields to ensure highly localized and precise dose delivery, challenging conventional clinical dosimetry protocols. The emergence of preclinical spatially fractionated synchrotron radiotherapies with high dose-rate, sub-millimetric parallel kilovoltage x-ray beams, has pushed clinical dosimetry to its limit. A commercially available synthetic single crystal diamond detector designed for small field dosimetry has been characterized to assess its potential as a dosimeter for synchrotron microbeam and minibeam radiotherapy. Methods: Experiments were carried out using a synthetic diamond detector on the imaging and medical beamline (IMBL) at the Australian Synchrotron. The energy dependence ofmore » the detector was characterized by cross-referencing with a calibrated ionization chamber in monoenergetic beams in the energy range 30–120 keV. The dose-rate dependence was measured in the range 1–700 Gy/s. Dosimetric quantities were measured in filtered white beams, with a weighted mean energy of 95 keV, in broadbeam and spatially fractionated geometries, and compared to reference dosimeters. Results: The detector exhibits an energy dependence; however, beam quality correction factors (k{sub Q}) have been measured for energies in the range 30–120 keV. The k{sub Q} factor for the weighted mean energy of the IMBL radiotherapy spectrum, 95 keV, is 1.05 ± 0.09. The detector response is independent of dose-rate in the range 1–700 Gy/s. The percentage depth dose curves measured by the diamond detector were compared to ionization chambers and agreed to within 2%. Profile measurements of microbeam and minibeam arrays were performed. The beams are well resolved and the full width at halfmaximum agrees with the nominal width of the beams. The peak to valley dose ratio (PVDR) calculated from the profiles at various depths in water agrees within experimental error with PVDR calculations from Gafchromic film data. Conclusions: The synthetic diamond detector is now well characterized and will be used to develop an experimental dosimetry protocol for spatially fractionated synchrotron radiotherapy.« less

Image guided IMRT dosimetry using anatomy specific MOSFET configurations.

PubMed

Amin, Md Nurul; Norrlinger, Bern; Heaton, Robert; Islam, Mohammad

2008-06-23

We have investigated the feasibility of using a set of multiple MOSFETs in conjunction with the mobile MOSFET wireless dosimetry system, to perform a comprehensive and efficient quality assurance (QA) of IMRT plans. Anatomy specific MOSFET configurations incorporating 5 MOSFETs have been developed for a specially designed IMRT dosimetry phantom. Kilovoltage cone beam computed tomography (kV CBCT) imaging was used to increase the positional precision and accuracy of the detectors and phantom, and so minimize dosimetric uncertainties in high dose gradient regions. The effectiveness of the MOSFET based dose measurements was evaluated by comparing the corresponding doses measured by an ion chamber. For 20 head and neck IMRT plans the agreement between the MOSFET and ionization chamber dose measurements was found to be within -0.26 +/- 0.88% and 0.06 +/- 1.94% (1 sigma) for measurement points in the high dose and low dose respectively. A precision of 1 mm in detector positioning was achieved by using the X-Ray Volume Imaging (XVI) kV CBCT system available with the Elekta Synergy Linear Accelerator. Using the anatomy specific MOSFET configurations, simultaneous measurements were made at five strategically located points covering high dose and low dose regions. The agreement between measurements and calculated doses by the treatment planning system for head and neck and prostate IMRT plans was found to be within 0.47 +/- 2.45%. The results indicate that a cylindrical phantom incorporating multiple MOSFET detectors arranged in an anatomy specific configuration, in conjunction with image guidance, can be utilized to perform a comprehensive and efficient quality assurance of IMRT plans.

Validation of Dosimetric Leaf Gap (DLG) prior to its implementation in Treatment Planning System (TPS): TrueBeam™ millennium 120 leaf MLC.

PubMed

Shende, Ravindra; Patel, Ganesh

2017-01-01

Objective of present study is to determine optimum value of DLG and its validation prior to being incorporated in TPS for Varian TrueBeam™ millennium 120 leaves MLC. Partial transmission through the rounded leaf ends of the Multi Leaf Collimator (MLC) causes a conflict between the edges of the light field and radiation field. Parameter account for this partial transmission is called Dosimetric Leaf Gap (DLG). The complex high precession technique, such as Intensity Modulated Radiation Therapy (IMRT), entails the modeling of optimum value of DLG inside Eclipse Treatment Planning System (TPS) for precise dose calculation. Distinct synchronized uniformed extension of sweeping dynamic MLC leaf gap fields created by Varian MLC shaper software were use to determine DLG. DLG measurements performed with both 0.13 cc semi-flex ionization chamber and 2D-Array I-Matrix were used to validate the DLG; similarly, values of DLG from TPS were estimated from predicted dose. Similar mathematical approaches were employed to determine DLG from delivered and TPS predicted dose. DLG determined from delivered dose measured with both ionization chamber (DLG Ion ) and I-Matrix (DLG I-Matrix ) compared with DLG estimate from TPS predicted dose (DLG TPS ). Measurements were carried out for all available 6MV, 10MV, 15MV, 6MVFFF and 10MVFFF beam energies. Maximum and minimum DLG deviation between measured and TPS calculated DLG was found to be 0.2 mm and 0.1 mm, respectively. Both of the measured DLGs (DLG Ion and DLG I-Matrix ) were found to be in a very good agreement with estimated DLG from TPS (DLG TPS ). Proposed method proved to be helpful in verifying and validating the DLG value prior to its clinical implementation in TPS.

The Mobile Dosimetric Telescope - A Small Size Active Personal Dosimeter for Application at High Altitudes and Onboard the International Space Station

NASA Astrophysics Data System (ADS)

Ritter, B.; Marsalek, K.; Berger, T.; Burmeister, S.; Reitz, G.; Heber, B.

2012-12-01

The radiation environment at cruising altitudes, as well as in Low Earth Orbit - like on the International Space Station - differs significantly from the natural radiation environment on Earth. Especially in Low Earth Orbit it poses one of the main health risks for long duration human missions. Therefore, it is essential to monitor the properties of the radiation field in such environments. The Mobile Dosimetric Telescope MDT, is a small size battery driven personal dosimeter based on silicon detector technology that has been developed to observe absorbed dose and dose rate in real time. Two silicon diodes are arranged in a telescope configuration, which allows the measurement of the ionizing constituents of the radiation field and partially the neutral contribution to the dose. The absorbed dose is obtained by considering every particle in either of the detectors. Particles traversing both diodes are detected as coincidence events that enable to derive linear energy transfer (LET) spectra. From these the quality factor of the field is determined, which is necessary for the estimation of the dose equivalent. The detection range of the device covers energy depositions from minimal ionizing particles up to relativistic heavy ions. Calibrations of the detector system have been performed with various radioactive sources and with heavy ions at the Heavy Ion Medical Accelerator (HIMAC) facility at the National Institute for Radiological Sciences (NIRS) in Chiba, Japan. Additionally, the MDT has been successfully tested onboard aircraft. The results of these measurements are in good agreement with those from other radiation detectors. The presentation will focus on data taken during long haul flights in the northern hemisphere.

Atmospheric radiation flight dose rates

NASA Astrophysics Data System (ADS)

Tobiska, W. K.

2015-12-01

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

Analysis of the response of PVA-GTA Fricke-gel dosimeters with clinical magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Collura, Giorgio; Gallo, Salvatore; Tranchina, Luigi; Abbate, Boris Federico; Bartolotta, Antonio; d'Errico, Francesco; Marrale, Maurizio

2018-01-01

Fricke gel dosimeters produced with a matrix of Poly-vinyl alcohol (PVA) cross-linked with glutaraldehyde (GTA) were analyzed with magnetic resonance imaging (MRI). Previous studies based on spectrophotometry showed valuable dosimetric features of these gels in terms of X-ray sensitivity and diffusion of the ferric ions produced after irradiation. In this study, MRI was performed on the gels at 1.5 T with a clinical scanner in order to optimize the acquisition parameters and obtain high contrast between irradiated and non-irradiated samples. The PVA gels were found to offer good linearity in the range of 0-10 Gy and a stable signal for several hours after irradiation. The sensitivity was about 40% higher compared to gels produced with agarose as gelling agent. The effect of xylenol orange (XO) on the MRI signal was also investigated: gel dosimeters made without XO show higher sensitivity to x-rays than those made with XO. The dosimetric accuracy of the 3D gels was investigated by comparing their MRI response to percentage depth dose and transversal dose profile measurements made with an ionization chamber in a water phantom. The comparison of PVA-GTA gels with and without XO showed that the chelating agent reduces the MRI sensitivity of the gels. Depth-dose and transversal dose profiles acquired by PVA-GTA gels without XO are more accurate and consistent with the ionization chamber data. However, diffusion effects hinder accurate measurements in the steep dose gradient regions and they should be further reduced by modifying the gel matrix and/or by minimizing the delay between irradiation and imaging.

Radiochromic film calibration for the RQT9 quality beam

NASA Astrophysics Data System (ADS)

Costa, K. C.; Gomez, A. M. L.; Alonso, T. C.; Mourao, A. P.

2017-11-01

When ionizing radiation interacts with matter it generates energy deposition. Radiation dosimetry is important for medical applications of ionizing radiation due to the increasing demand for diagnostic radiology and radiotherapy. Different dosimetry methods are used and each one has its advantages and disadvantages. The film is a dose measurement method that records the energy deposition by the darkening of its emulsion. Radiochromic films have a little visible light sensitivity and respond better to ionizing radiation exposure. The aim of this study is to obtain the resulting calibration curve by the irradiation of radiochromic film strips, making it possible to relate the darkening of the film with the absorbed dose, in order to measure doses in experiments with X-ray beam of 120 kV, in computed tomography (CT). Film strips of GAFCHROMIC XR-QA2 were exposed according to RQT9 reference radiation, which defines an X-ray beam generated from a voltage of 120 kV. Strips were irradiated in "Laboratório de Calibração de Dosímetros do Centro de Desenvolvimento da Tecnologia Nuclear" (LCD / CDTN) at a dose range of 5-30 mGy, corresponding to the range values commonly used in CT scans. Digital images of the irradiated films were analyzed by using the ImageJ software. The darkening responses on film strips according to the doses were observed and they allowed obtaining the corresponding numeric values to the darkening for each specific dose value. From the numerical values of darkening, a calibration curve was obtained, which correlates the darkening of the film strip with dose values in mGy. The calibration curve equation is a simplified method for obtaining absorbed dose values using digital images of radiochromic films irradiated. With the calibration curve, radiochromic films may be applied on dosimetry in experiments on CT scans using X-ray beam of 120 kV, in order to improve CT acquisition image processes.

TH-CD-201-03: A Real-Time Method to Simultaneously Measure Linear Energy Transfer and Dose for Proton Therapy Using Organic Scintillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alsanea, F; Therriault-Proulx, F; Sawakuchi, G

Purpose: The light generated in organic scintillators depends on both the radiation dose and the linear energy transfer (LET). The LET dependence leads to an under-response of the detector in the Bragg peak of proton beams. This phenomenon, called ionization quenching, must be corrected to obtain accurate dose measurements of proton beams. This work exploits the ionization quenching phenomenon to provide a method of measuring LET and auto correcting quenching. Methods: We exposed simultaneously four different organic scintillators (BCF-12, PMMA, PVT, and LSD; 1mm in diameter) and a plane parallel ionization chamber in passively scattered proton beams to doses betweenmore » 32 and 43 cGy and fluence averaged LET values from 0.47 to 1.26 keV/µm. The LET values for each irradiation condition were determined using a validated Monte Carlo model of the beam line. We determined the quenching parameter in the Birk’s equation for scintillation in BCF-12 for dose measurements. One set of irradiation conditions was used to correlate the scintillation response ratio to the LET values and plot a scintillation response ratio versus LET calibration curve. Irradiation conditions independent from the calibration ones were used to validate this method. Comparisons to the expected values were made on both the basis of dose and LET. Results: Among all the scintillators investigated, the ratio of PMMA to BCF-12 provided the best correlation to LET values and was used as the LET calibration curve. The expected LET values in the validation set were within 2%±6%, which resulted in dose accuracy of 1.5%±5.8% for the range of LET values investigated in this work. Conclusion: We have demonstrated the feasibility of using the ratio between the light output of two organic scintillators to simultaneously measure LET and dose of therapeutic proton beams. Further studies are needed to verify the response in higher LET values.« less

Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry.

PubMed

Di Venanzio, C; Marinelli, Marco; Milani, E; Prestopino, G; Verona, C; Verona-Rinati, G; Falco, M D; Bagalà, P; Santoni, R; Pimpinella, M

2013-02-01

To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and a p-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1σ) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below ±0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy∕min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.

Copper-silver ionization at a US hospital: interaction of treated drinking water with plumbing materials, aesthetics and other considerations

EPA Science Inventory

Tap water sampling and surface analysis of copper pipe/bathroom porcelain were performed to explore the fate of copper and silver during the first nine months of copper-silver ionization (CSI) applied to cold and hot water at a hospital in Cincinnati, Ohio. Ions dosed by CSI into...

Calibration and error analysis of metal-oxide-semiconductor field-effect transistor dosimeters for computed tomography radiation dosimetry.

PubMed

Trattner, Sigal; Prinsen, Peter; Wiegert, Jens; Gerland, Elazar-Lars; Shefer, Efrat; Morton, Tom; Thompson, Carla M; Yagil, Yoad; Cheng, Bin; Jambawalikar, Sachin; Al-Senan, Rani; Amurao, Maxwell; Halliburton, Sandra S; Einstein, Andrew J

2017-12-01

Metal-oxide-semiconductor field-effect transistors (MOSFETs) serve as a helpful tool for organ radiation dosimetry and their use has grown in computed tomography (CT). While different approaches have been used for MOSFET calibration, those using the commonly available 100 mm pencil ionization chamber have not incorporated measurements performed throughout its length, and moreover, no previous work has rigorously evaluated the multiple sources of error involved in MOSFET calibration. In this paper, we propose a new MOSFET calibration approach to translate MOSFET voltage measurements into absorbed dose from CT, based on serial measurements performed throughout the length of a 100-mm ionization chamber, and perform an analysis of the errors of MOSFET voltage measurements and four sources of error in calibration. MOSFET calibration was performed at two sites, to determine single calibration factors for tube potentials of 80, 100, and 120 kVp, using a 100-mm-long pencil ion chamber and a cylindrical computed tomography dose index (CTDI) phantom of 32 cm diameter. The dose profile along the 100-mm ion chamber axis was sampled in 5 mm intervals by nine MOSFETs in the nine holes of the CTDI phantom. Variance of the absorbed dose was modeled as a sum of the MOSFET voltage measurement variance and the calibration factor variance, the latter being comprised of three main subcomponents: ionization chamber reading variance, MOSFET-to-MOSFET variation and a contribution related to the fact that the average calibration factor of a few MOSFETs was used as an estimate for the average value of all MOSFETs. MOSFET voltage measurement error was estimated based on sets of repeated measurements. The calibration factor overall voltage measurement error was calculated from the above analysis. Calibration factors determined were close to those reported in the literature and by the manufacturer (~3 mV/mGy), ranging from 2.87 to 3.13 mV/mGy. The error σ V of a MOSFET voltage measurement was shown to be proportional to the square root of the voltage V: σV=cV where c = 0.11 mV. A main contributor to the error in the calibration factor was the ionization chamber reading error with 5% error. The usage of a single calibration factor for all MOSFETs introduced an additional error of about 5-7%, depending on the number of MOSFETs that were used to determine the single calibration factor. The expected overall error in a high-dose region (~30 mGy) was estimated to be about 8%, compared to 6% when an individual MOSFET calibration was performed. For a low-dose region (~3 mGy), these values were 13% and 12%. A MOSFET calibration method was developed using a 100-mm pencil ion chamber and a CTDI phantom, accompanied by an absorbed dose error analysis reflecting multiple sources of measurement error. When using a single calibration factor, per tube potential, for different MOSFETs, only a small error was introduced into absorbed dose determinations, thus supporting the use of a single calibration factor for experiments involving many MOSFETs, such as those required to accurately estimate radiation effective dose. © 2017 American Association of Physicists in Medicine.

Experimental verification of gain drop due to general ion recombination for a carbon-ion pencil beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tansho, Ryohei, E-mail: r-tansho@nirs.go.jp; Furukawa, Takuji; Hara, Yousuke

Purpose: Accurate dose measurement in radiotherapy is critically dependent on correction for gain drop, which is the difference of the measured current from the ideal saturation current due to general ion recombination. Although a correction method based on the Boag theory has been employed, the theory assumes that ionized charge density in an ionization chamber (IC) is spatially uniform throughout the irradiation volume. For particle pencil beam scanning, however, the charge density is not uniform, because the fluence distribution of a pencil beam is not uniform. The aim of this study was to verify the effect of the nonuniformity ofmore » ionized charge density on the gain drop due to general ion recombination. Methods: The authors measured the saturation curve, namely, the applied voltage versus measured current, using a large plane-parallel IC and 24-channel parallel-plate IC with concentric electrodes. To verify the effect of the nonuniform ionized charge density on the measured saturation curve, the authors calculated the saturation curve using a method which takes into account the nonuniform ionized charge density and compared it with the measured saturation curves. Results: Measurement values of the different saturation curves in the different channels of the concentric electrodes differed and were consistent with the calculated values. The saturation curves measured by the large plane-parallel IC were also consistent with the calculation results, including the estimation error of beam size and of setup misalignment. Although the impact of the nonuniform ionized charge density on the gain drop was clinically negligible with the conventional beam intensity, it was expected that the impact would increase with higher ionized charge density. Conclusions: For pencil beam scanning, the assumption of the conventional Boag theory is not valid. Furthermore, the nonuniform ionized charge density affects the prediction accuracy of gain drop when the ionized charge density is increased by a higher dose rate and/or lower beam size.« less

Effects of ionizing radiation on bone cell differentiation in an experimental murine bone cell model

NASA Astrophysics Data System (ADS)

Baumstark-Khan, Christa; Lau, Patrick; Hellweg, Christine; Reitz, Guenther

During long-term space travel astronauts are exposed to a complex mixture of different radiation types under conditions of dramatically reduced weight-bearing activity. It has been validated that astronauts loose a considerable amount of bone mass at a rate up to one to two percent each month in space. Therapeutic doses of ionizing radiation cause bone damage and increase fracture risks after treatment for head-and-neck cancer and in pelvic irradiation. For low radiation doses, the possibility of a disturbed healing potential of bone was described. Radiation induced damage has been discussed to inflict mainly on immature and healing bone. Little is known about radiation effects on bone remodelling and even less on the combined action of microgravity and radiation. Bone remodelling is a life-long process performed by balanced action of cells from the osteoblast and osteoclast lineages. While osteoblasts differentiate either into bone-lining cells or into osteocytes and play a crucial role in bone matrix synthesis, osteoclasts are responsible for bone resorption. We hypothesize that the balance between bone matrix assembly by osteocytes and bone degradation by osteoclasts is modulated by microgravity as well as by ionizing radiation. To address this, a cell model consisting of murine cell lines with the potential to differentiate into bone-forming osteoblasts (OCT-1, MC3T3-E1 S24, and MC3T3-E1 S4) was used for studying radiation response after exposure to simulated components of cosmic radiation. Cells were exposed to graded doses of 150 kV X-rays, α particles (0.525 MeV/u, 160 keV/µm; PTB, Braunschweig, Germany) and accelerated heavy ions (75 MeV/u carbon, 29 keV/µm; 95 MeV/u argon, 230 keV/µm; GANIL, Caen, France). Cell survival was measured as colony forming ability; cell cycle progression was analyzed via fluorescence-activated cell scanning (FACS) by measurement of the content of propidium iodide-stained DNA, DNA damage was visualized by γH2AX-immunostaining. Osteoblastogenesis was estimated by measurement of alkaline phosphatase (ALP) activity and production of mineralized matrix (von-Kossa staining, Alizarin Red staining). During the process of osteoblastic cell differentiation, the expression of the bone specific marker genes osteocalcin (OCN) and osteopontin (OPN) were recorded by quantitative real time reverse transcription PCR (qRT-PCR). Compared with standard culture conditions, the osteogenic marker genes OCN and OPN were highly expressed during the differentiation process induced either by osteo-inductive media additives (50 µg/ml ascorbic acid, 10 mmol/l β-glycero phosphate) or by sparsely ionizing radiation (X-rays). After 21 days of postirradiation incubation sparsely ionizing radiation could be shown to induce the formation of bone-like nodules (von-Kossa staining) for OCT-1 and MC3T3-E1 S4 cells but nor for MC3T3- E1 S24 cells. Ionizing radiation leads to a cell cycle arrest which is resolved in a dose and time dependent way. This was accompanied by a dose dependent regulation of the cyclin kinase inhibitor CDKN1A (p21/WAF) and transforming growth factor beta 1 (TGF-β1). TGF-β1 is known to affect osteoblast differentiation, matrix formation and mineralization. Modulation of its expression could influence the expression of main osteogenic transcription factors. For exposure with high LET radiation a pronounced cell cycle block was evident. The expression of the osteogenic marker genes OCN and Osterix (OSX) was increased in the OCT-1 cells with differentiation potential for exposure to α particles and accelerated carbon and argon ions. The results on the expression of differentiation markers during radiation-induced premature differentiation of bone cells of the osteoblast lineage show that densely ionizing radiation results in expression of proteins essential for bone formation and consequently in an increase in bone volume. Such an effect has been observed in in-vivo carbon ion irradiated rats. As radiation dependent permanent cell cycle blocks lead to a depletion of proliferation-competent cells from the osteoblastic precursor pool in the body, a gradual decrease of bone mass in weightlessness may be attributed to synergistic effects of radiation and weightlessness.

Radiation immune RAM semiconductor technology for the 80's. [Random Access Memory

NASA Technical Reports Server (NTRS)

Hanna, W. A.; Panagos, P.

1983-01-01

This paper presents current and short term future characteristics of RAM semiconductor technologies which were obtained by literature survey and discussions with cognizant Government and industry personnel. In particular, total ionizing dose tolerance and high energy particle susceptibility of the technologies are addressed. Technologies judged compatible with spacecraft applications are ranked to determine the best current and future technology for fast access (less than 60 ns), radiation tolerant RAM.

Radiation Effects On Emerging Electronic Materials And Devices

DTIC Science & Technology

2010-01-17

RADIATION EFFECTS ON EMERGING ELECTRONIC MATERIALS AND DEVICES FINAL PERFORMANCE REPORT PREPARED FOR: Kitt Reinhardt AFOSR/NE 875 N...and the other with metal gates and a high-K gate dielectric. These devices were programmed using both back-gate pulse and gate induced drain leakage... metal gate process GIDL method Fig. 1. Sensing margin as a function of total ionizing dose for nMOS 1T-DRAM cells programmed by back-gate pulse and

Proton beam dosimetry: a comparison between a plastic scintillator, ionization chamber and Faraday cup.

PubMed

Ghergherehchi, Mitra; Afarideh, Hossein; Ghannadi, Mohammad; Mohammadzadeh, Ahmad; Aslani, Golam Reza; Boghrati, Behzad

2010-01-01

In this study, a comparison was made between a plastic scintillator (BC400), a Faraday Cup (FC) and an ionization chamber (IC) used for routine proton dosimetry. Thin scintillators can be applied to proton dosimetry and consequently to proton therapy as relative dosimeters because of their water-equivalent nature, high energy-light conversion efficiency, low dimensions and good proportionality to the absorbed dose at low stopping powers. To employ such scintillators as relative dosimeters in proton therapy, the corrective factors must be applied to correct the quenching luminescence at the Bragg peak. A fine linear proportionality between the luminescence light yield Y and the proton flux in a thin (0.5 mm) scintillator for the 20 and 30 MeV proton beams were observed. The experimental peak/plateau ratios of Bragg Curve for 2, 1 and 0.5 mm scintillators with an accuracy of 0.5% were obtained to be 1.87, 1.91 and 2.30, respectively. With combination of the Markus chamber and the CR-39 detector, the peak/plateau ratio was improved to 3.26. The obtained data of the luminescence yield as a function of the specific energy loss is in agreement with the Craun-Birk's theory. Results show that the FC and Markus ionization chamber are in agreement within 4%, while the FC gives a lower dose evaluation. For a defined beam, the data for the fluence measurements are reproducible within a good accuracy.

NASA GeneLab Project: Bridging Space Radiation Omics with Ground Studies

NASA Technical Reports Server (NTRS)

Beheshti, Afshin; Miller, Jack; Kidane, Yared H.; Berrios, Daniel; Gebre, Samrawit G.; Costes, Sylvain V.

2018-01-01

Accurate assessment of risk factors for long-term space missions is critical for human space exploration: therefore it is essential to have a detailed understanding of the biological effects on humans living and working in deep space. Ionizing radiation from Galactic Cosmic Rays (GCR) is one of the major risk factors factor that will impact health of astronauts on extended missions outside the protective effects of the Earth's magnetic field. Currently there are gaps in our knowledge of the health risks associated with chronic low dose, low dose rate ionizing radiation, specifically ions associated with high (H) atomic number (Z) and energy (E). The GeneLab project (genelab.nasa.gov) aims to provide a detailed library of Omics datasets associated with biological samples exposed to HZE. The GeneLab Data System (GLDS) currently includes datasets from both spaceflight and ground-based studies, a majority of which involve exposure to ionizing radiation. In addition to detailed information for ground-based studies, we are in the process of adding detailed, curated dosimetry information for spaceflight missions. GeneLab is the first comprehensive Omics database for space related research from which an investigator can generate hypotheses to direct future experiments utilizing both ground and space biological radiation data. In addition to previously acquired data, the GLDS is continually expanding as Omics related data are generated by the space life sciences community. Here we provide a brief summary of space radiation related data available at GeneLab.

Single hair analysis of small molecules using MALDI-triple quadrupole MS imaging and LC-MS/MS: investigations on opportunities and pitfalls.

PubMed

Poetzsch, Michael; Steuer, Andrea E; Roemmelt, Andreas T; Baumgartner, Markus R; Kraemer, Thomas

2014-12-02

Single hair analysis normally requires extensive sample preparation microscale protocols including time-consuming steps like segmentation and extraction. Matrix assisted laser desorption and ionization mass spectrometric imaging (MALDI-MSI) was shown to be an alternative tool in single hair analysis, but still, questions remain. Therefore, an investigation of MALDI-MSI in single hair analysis concerning the extraction process, usage of internal standard (IS), and influences on the ionization processes were systematically investigated to enable the reliable application to hair analysis. Furthermore, single dose detection, quantitative correlation to a single hair, and hair strand LC-MS/MS results were performed, and the performance was compared to LC-MS/MS single hair monitoring. The MALDI process was shown to be independent from natural hair color and not influenced by the presence of melanin. Ionization was shown to be reproducible along and in between different hair samples. MALDI image intensities in single hair and hair snippets showed good semiquantitative correlation to zolpidem hair concentrations obtained from validated routine LC-MS/MS methods. MALDI-MSI is superior to LC-MS/MS analysis when a fast, easy, and cheap sample preparation is necessary, whereas LC-MS/MS showed higher sensitivity with the ability of single dose detection for zolpidem. MALDI-MSI and LC-MS/MS segmental single hair analysis showed good correlation, and both are suitable for consumption monitoring of drugs of abuse with a high time resolution.

Radiation effects in interventional radiology using biological and physical dosimetry methods: a case-control study.

PubMed

Ramos, Miguel; Montoro, Alegria; Almonacid, Miguel; Ferrer, Silvia; Barquinero, Joan Francesc; Tortosa, Ricardo; Verdú, Gumersindo; Rodríguez, Pilar; Barrios, Lleonard; Villaescusa, Juan Ignacio

2008-01-01

Interventional radiologists and staff members are frequently exposed to protracted and fractionated low doses of ionizing radiation, which extend during all their professional activities. These exposures can derive, due to the irradiation of skin tissues and peripheral blood, in deterministic effects (radiodermitis, aged skin, hands depilation) or stochastic ones (skin and non-solid cancers incidence). Epidemiological studies of population exposed to ionizing radiation provide information of radio-induced effects. The radiation risk or radiological detriment has been estimated from a group of six exposed interventionist radiologists of the Hospital La Fe (Valencia, Spain). Dosimetry has been periodically registered from TLDs and wrist dosimeters (physical methods) and estimated through translocations in lymphocytes of peripheral blood (biological methods), by extrapolating the yield of translocations to their respective dose-effect curves. The probability of non-melanoma skin cancer and leukaemia (acute myelogenous, acute lymphocytic and chronic myelogenous leukaemia) incidence has been estimated through the software RADRISK. This software is based on a transport model from epidemiological studies of population exposed to external low-LET ionizing radiation [1]. Other non-solid carcinomas have not been considered due to their low statistical power, such as myeloid and non-Hodgkin lymphomas. The discrepancies observed between the physically recorded doses and biological estimated doses could indicate that exposed workers did not always wear their dosimeters or these dosimeters were not always exposed to the radiation field.

Dosimetric characterization of a synthetic single crystal diamond detector in a clinical 62 MeV ocular therapy proton beam

NASA Astrophysics Data System (ADS)

Marinelli, Marco; Pompili, F.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Cirrone, G. A. P.; Cuttone, G.; La Rosa, R. M.; Raffaele, L.; Romano, F.; Tuvè, C.

2014-12-01

A synthetic single crystal diamond based Schottky photodiode was tested at INFN-LNS on the proton beam line (62 MeV) dedicated to the radiation treatment of ocular disease. The diamond detector response was studied in terms of pre-irradiation dose, linearity with dose and dose rate, and angular dependence. Depth dose curves were measured for the 62 MeV pristine proton beam and for three unmodulated range-shifted proton beams; furthermore, the spread-out Bragg peak was measured for a modulated therapeutic proton beam. Beam parameters, recommended by the ICRU report 78, were evaluated to analyze depth-dose curves from diamond detector. Measured dose distributions were compared with the corresponding dose distributions acquired with reference plane-parallel ionization chambers. Field size dependence of the output factor (dose per monitor unit) in a therapeutic modulated proton beam was measured with the diamond detector over the range of ocular proton therapy collimator diameters (5-30 mm). Output factors measured with the diamond detector were compared to the ones by a Markus ionization chamber, a Scanditronix Hi-p Si stereotactic diode and a radiochromic EBT2 film. Signal stability within 0.5% was demonstrated for the diamond detector with no need of any pre-irradiation dose. Dose and dose rate dependence of the diamond response was measured: deviations from linearity resulted to be within ±0.5% over the investigated ranges of 0.5-40.0 Gy and 0.3-30.0 Gy/min respectively. Output factors from diamond detector measured with the smallest collimator (5 mm in diameter) showed a maximum deviation of about 3% with respect to the high resolution radiochromic EBT2 film. Depth-dose curves measured by diamond for unmodulated and modulated beams were in good agreement with those from the reference plane-parallel Markus chamber, with relative differences lower than ±1% in peak-to-plateau ratios, well within experimental uncertainties. A 2.5% variation in diamond detector response was observed in angular dependence measurements carried-out by varying the proton beam incidence angle in the polar direction. The dosimetric characterization of the tested synthetic single crystal diamond detector clearly indicates its suitability for relative dosimetry in ocular therapy proton beams, with no need of any correction factors accounting for dose rate and linear energy transfer dependence.

Simultaneous effects of photo- and radio- darkening in ytterbium-doped aluminosilicate fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duchez, Jean-Bernard, E-mail: jbduchez@unice.fr; Mady, Franck, E-mail: jbduchez@unice.fr; Mebrouk, Yasmine, E-mail: jbduchez@unice.fr

2014-10-21

We present original characterizations of photo-radio-darkening in ytterbium-doped silica optical fibers submitted to the simultaneous action of the pump and of an ionizing radiation. We present the interplay between both radiations, showing e.g. that the pump is able to darken or bleach the fiber depending on the ionizing dose. The photo-resistance of the fiber is shown to play a crucial role on its radio-resistance, and that photo-resistant fibers should be also radio-resistant in low dose rate conditions. All the results are thoroughly explained by a physical model presented in a separate article by Mady et al. (this conference proceeding)

Simulation and measurement of total ionizing dose radiation induced image lag increase in pinned photodiode CMOS image sensors

NASA Astrophysics Data System (ADS)

Liu, Jing; Chen, Wei; Wang, Zujun; Xue, Yuanyuan; Yao, Zhibin; He, Baoping; Ma, Wuying; Jin, Junshan; Sheng, Jiangkun; Dong, Guantao

2017-06-01

This paper presents an investigation of total ionizing dose (TID) induced image lag sources in pinned photodiodes (PPD) CMOS image sensors based on radiation experiments and TCAD simulation. The radiation experiments have been carried out at the Cobalt -60 gamma-ray source. The experimental results show the image lag degradation is more and more serious with increasing TID. Combining with the TCAD simulation results, we can confirm that the junction of PPD and transfer gate (TG) is an important region forming image lag during irradiation. These simulations demonstrate that TID can generate a potential pocket leading to incomplete transfer.

Cardiovascular changes in atherosclerotic ApoE-deficient mice exposed to Co60 (γ) radiation.

PubMed

Kumarathasan, Prem; Vincent, Renaud; Blais, Erica; Saravanamuthu, Anu; Gupta, Pallavi; Wyatt, Heather; Mitchel, Ronald; Hannan, Mohammed; Trivedi, Akilesh; Whitman, Stewart

2013-01-01

There is evidence for a role of ionizing radiation in cardiovascular diseases. The goal of this work was to identify changes in oxidative and nitrative stress pathways and the status of the endothelinergic system during progression of atherosclerosis in ApoE-deficient mice after single and repeated exposure to ionizing radiation. B6.129P2-ApoE tmlUnc mice on a low-fat diet were acutely exposed (whole body) to Co60 (γ) (single dose 0, 0.5, and 2 Gy) at a dose rate of 36.32 cGy/min, or repeatedly (cumulative dose 0 and 2 Gy) at a dose-rate of 0.1 cGy/min for 5 d/wk, over a period of 4 weeks. Biological endpoints were investigated after 3-6 months of recovery post-radiation. The nitrative stress marker 3-nitrotyrosine and the vasoregulator peptides endothelin-1 and endothelin-3 in plasma were increased (p<0.05) in a dose-dependent manner 3-6 months after acute or chronic exposure to radiation. The oxidative stress marker 8-isoprostane was not affected by radiation, while plasma 8-hydroxydeoxyguanosine and L-3,4-dihydroxyphenylalanine decreased (p<0.05) after treatment. At 2Gy radiation dose, serum cholesterol was increased (p = 0.008) relative to controls. Percent lesion area increased (p = 0.005) with age of animal, but not with radiation treatment. Our observations are consistent with persistent nitrative stress and activation of the endothelinergic system in ApoE-/- mice after low-level ionizing radiation exposures. These mechanisms are known factors in the progression of atherosclerosis and other cardiovascular diseases.

TU-G-BRD-04: A Round Robin Dosimetry Intercomparison of Gamma Stereotactic Radiosurgery Calibration Protocols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drzymala, R; Alvarez, P; Bednarz, G

2015-06-15

Purpose: The purpose of this multi-institutional study was to compare two new gamma stereotactic radiosurgery (GSRS) dosimetry protocols to existing calibration methods. The ultimate goal was to guide AAPM Task Group 178 in recommending a standard GSRS dosimetry protocol. Methods: Nine centers (ten GSRS units) participated in the study. Each institution made eight sets of dose rate measurements: six with two different ionization chambers in three different 160mm-diameter spherical phantoms (ABS plastic, Solid Water and liquid water), and two using the same ionization chambers with a custom in-air positioning jig. Absolute dose rates were calculated using a newly proposed formalismmore » by the IAEA working group for small and non-standard radiation fields and with a new air-kerma based protocol. The new IAEA protocol requires an in-water ionization chamber calibration and uses previously reported Monte-Carlo generated factors to account for the material composition of the phantom, the type of ionization chamber, and the unique GSRS beam configuration. Results obtained with the new dose calibration protocols were compared to dose rates determined by the AAPM TG-21 and TG-51 protocols, with TG-21 considered as the standard. Results: Averaged over all institutions, ionization chambers and phantoms, the mean dose rate determined with the new IAEA protocol relative to that determined with TG-21 in the ABS phantom was 1.000 with a standard deviation of 0.008. For TG-51, the average ratio was 0.991 with a standard deviation of 0.013, and for the new in-air formalism it was 1.008 with a standard deviation of 0.012. Conclusion: Average results with both of the new protocols agreed with TG-21 to within one standard deviation. TG-51, which does not take into account the unique GSRS beam configuration or phantom material, was not expected to perform as well as the new protocols. The new IAEA protocol showed remarkably good agreement with TG-21. Conflict of Interests: Paula Petti, Josef Novotny, Gennady Neyman and Steve Goetsch are consultants for Elekta Instrument A/B; Elekta Instrument AB, PTW Freiburg GmbH, Standard Imaging, Inc., and The Phantom Laboratory, Inc. loaned equipment for use in these experiments; The University of Wisconsin Accredited Dosimetry Calibration Laboratory provided calibration services.« less

Signaling pathways underpinning the manifestations of ionizing radiation-induced bystander effects.

PubMed

Hamada, Nobuyuki; Maeda, Munetoshi; Otsuka, Kensuke; Tomita, Masanori

2011-06-01

For nearly a century, ionizing radiation has been indispensable to medical diagnosis. Furthermore, various types of electromagnetic and particulate radiation have also been used in cancer therapy. However, the biological mechanism of radiation action remains incompletely understood. In this regard, a rapidly growing body of experimental evidence indicates that radiation exposure induces biological effects in cells whose nucleus has not been irradiated. This phenomenon termed the 'non-targeted effects' challenges the long-held tenet that radiation traversal through the cell nucleus is a prerequisite to elicit genetic damage and biological responses. The non-targeted effects include biological effects in cytoplasm-irradiated cells, bystander effects that arise in non-irradiated cells having received signals from irradiated cells, and genomic instability occurring in the progeny of irradiated cells. Such non-targeted responses are interrelated, and the bystander effect is further related with an adaptive response that manifests itself as the attenuated stressful biological effects of acute high-dose irradiation in cells that have been pre-exposed to low-dose or low-dose-rate radiation. This paper reviews the current body of knowledge about the bystander effect with emphasis on experimental approaches, in vitro and in vivo manifestations, radiation quality dependence, temporal and spatial dependence, proposed mechanisms, and clinical implications. Relations of bystander responses with the effects in cytoplasm-irradiated cells, genomic instability and adaptive response will also be briefly discussed.

High dose gamma ray exposure effect on the properties of CdSe nanowires

NASA Astrophysics Data System (ADS)

Narula, Chetna; Chauhan, R. P.

2018-03-01

We report high dose gamma-ray (γ-ray) induced modifications incurred by polycrystalline cadmium selenide (CdSe) nanowires of 80 nm diameter. The nanowires have been synthesized using polycarbonate template assisted electro-deposition technique. The samples were irradiated with 60Co γ-radiation at a dose rate of 4.533 kGy/h for different time intervals with doses varying from 0 to 400 kGy. The effects of γ rays on the structural, morphological, optical and electrical properties of nanowires are discussed. XRD patterns of as-synthesized and gamma irradiated CdSe nanowires did not show any phase transformations but the variation in relative intensity was observed. The crystallite size evaluated using Scherrer's formula was found to vary. The optical parameters were obtained using UV-vis spectrometer measurements of absorption. Band gap was found to decrease with γ irradiation up to a dose of 300 kGy after which it was seen to increase. Refractive index and optical dielectric constants were also evaluated. Subjection of γ-radiation also brings about key changes in the electrical properties of CdSe nanowires. The attained data shows that the electrical conductivity varies with absorbed dose. The variations in the properties of CdSe nanowires can be considered as a consequence of ionization process, defect production and its annihilation.

Adaptive response in human blood lymphocytes exposed to non-ionizing radiofrequency fields: resistance to ionizing radiation-induced damage.

PubMed

Sannino, Anna; Zeni, Olga; Romeo, Stefania; Massa, Rita; Gialanella, Giancarlo; Grossi, Gianfranco; Manti, Lorenzo; Vijayalaxmi; Scarfì, Maria Rosaria

2014-03-01

The aim of this preliminary investigation was to assess whether human peripheral blood lymphocytes which have been pre-exposed to non-ionizing radiofrequency fields exhibit an adaptive response (AR) by resisting the induction of genetic damage from subsequent exposure to ionizing radiation. Peripheral blood lymphocytes from four healthy donors were stimulated with phytohemagglutinin for 24 h and then exposed for 20 h to 1950 MHz radiofrequency fields (RF, adaptive dose, AD) at an average specific absorption rate of 0.3 W/kg. At 48 h, the cells were subjected to a challenge dose (CD) of 1.0 or 1.5 Gy X-irradiation (XR, challenge dose, CD). After a 72 h total culture period, cells were collected to examine the incidence of micronuclei (MN). There was a significant decrease in the number of MN in lymphocytes exposed to RF + XR (AD + CD) as compared with those subjected to XR alone (CD). These observations thus suggested a RF-induced AR and induction of resistance to subsequent damage from XR. There was variability between the donors in RF-induced AR. The data reported in our earlier investigations also indicated a similar induction of AR in human blood lymphocytes that had been pre-exposed to RF (AD) and subsequently treated with a chemical mutagen, mitomycin C (CD). Since XR and mitomycin-C induce different kinds of lesions in cellular DNA, further studies are required to understand the mechanism(s) involved in the RF-induced adaptive response.

LAURISTON S. TAYLOR LECTURE ON RADIATION PROTECTION AND MEASURMENTS: WHAT MAKES PARTICLE RADIATION SO EFFECTIVE?

PubMed Central

Blakely, Eleanor A.

2012-01-01

The scientific basis for the physical and biological effectiveness of particle radiations has emerged from many decades of meticulous basic research. A diverse array of biologically relevant consequences at the molecular, cellular, tissue, and organism level have been reported, but what are the key processes and mechanisms that make particle radiation so effective, and what competing processes define dose dependences? Recent studies have shown that individual genotypes control radiation-regulated genes and pathways in response to radiations of varying ionization density. The fact that densely ionizing radiations can affect different gene families than sparsely ionizing radiations, and that the effects are dose- and time-dependent has opened up new areas of future research. The complex microenvironment of the stroma, and the significant contributions of the immune response have added to our understanding of tissue-specific differences across the linear energy transfer (LET) spectrum. The importance of targeted vs. nontargeted effects remain a thorny, but elusive and important contributor to chronic low dose radiation effects of variable LET that still needs further research. The induction of cancer is also LET-dependent, suggesting different mechanisms of action across the gradient of ionization density. The focus of this 35th Lauriston S. Taylor Lecture is to chronicle the step-by-step acquisition of experimental clues that have refined our understanding of what makes particle radiation so effective, with emphasis on the example of radiation effects on the crystalline lens of the human eye. PMID:23032880

Adaptive response in human blood lymphocytes exposed to non-ionizing radiofrequency fields: resistance to ionizing radiation-induced damage

PubMed Central

Sannino, Anna; Zeni, Olga; Romeo, Stefania; Massa, Rita; Gialanella, Giancarlo; Grossi, Gianfranco; Manti, Lorenzo; Vijayalaxmi; Scarfì, Maria Rosaria

2014-01-01

The aim of this preliminary investigation was to assess whether human peripheral blood lymphocytes which have been pre-exposed to non-ionizing radiofrequency fields exhibit an adaptive response (AR) by resisting the induction of genetic damage from subsequent exposure to ionizing radiation. Peripheral blood lymphocytes from four healthy donors were stimulated with phytohemagglutinin for 24 h and then exposed for 20 h to 1950 MHz radiofrequency fields (RF, adaptive dose, AD) at an average specific absorption rate of 0.3 W/kg. At 48 h, the cells were subjected to a challenge dose (CD) of 1.0 or 1.5 Gy X-irradiation (XR, challenge dose, CD). After a 72 h total culture period, cells were collected to examine the incidence of micronuclei (MN). There was a significant decrease in the number of MN in lymphocytes exposed to RF + XR (AD + CD) as compared with those subjected to XR alone (CD). These observations thus suggested a RF-induced AR and induction of resistance to subsequent damage from XR. There was variability between the donors in RF-induced AR. The data reported in our earlier investigations also indicated a similar induction of AR in human blood lymphocytes that had been pre-exposed to RF (AD) and subsequently treated with a chemical mutagen, mitomycin C (CD). Since XR and mitomycin-C induce different kinds of lesions in cellular DNA, further studies are required to understand the mechanism(s) involved in the RF-induced adaptive response. PMID:23979077

Study of ionizing radiation on the properties of polyamide 6 with fiberglass reinforcement

NASA Astrophysics Data System (ADS)

Pinto, Clovis; Silva, Leonardo G. Andrade e.

2007-11-01

The use of polymers reinforced with fiberglass is becoming more and more common in the switches for household industries. These compounds perform a good tension resistance to the impact and the humidity absorption being used at the present time and also are in the automobile industry in parts underneath the hood, especially in the radiator frames. The aim of this work is to study the effect of ionizing radiation on the properties of polyamide 6 with fiberglass reinforcement and undergone to different irradiation doses. Samples were prepared and irradiated on JOB 188 accelerator with an electron beam energy of 1.5 MeV in air with different doses and a dose rate of 27.99 kGy/h. Afterward, the properties of the non-irradiated and irradiated polyamide 6 with fiberglass reinforcement were evaluated.

Breast cancer risk from low-dose exposures to ionizing radiation: results of parallel analysis of three exposed populations of women

DOE Office of Scientific and Technical Information (OSTI.GOV)

Land, C.E.; Boice, J.D. Jr.; Shore, R.E.

1980-08-01

Breast cancer incidence data were analyzed from three populations of women exposed to ionizing radiation: survivors of the Hiroshima and Nagasaki atomic bombs, patients in Massachusetts tuberculosis sanitoria who were exposed to multiple chest fluoroscopies, and patients treated by X-rays for acute postpartum mastitis in Rochester, New York. Parallel analyses by radiation dose, age at exposure, and time after exposure suggested that risk of radiation-induced cancer increased approximately linearly with increasing dose and was heavily dependent on age at exposure; however, the risk was otherwise remarkably similar among the three populations, at least for ages 10 to 40 years atmore » exposure, and followed the same temporal pattern of occurrence as did breast cancer incidence in nonexposed women of similar ages.« less

Detection of irradiated chicken by ESR spectroscopy of bone

NASA Astrophysics Data System (ADS)

Duarte, C. L.; Villavicencio, A. L. C. H.; Del Mastro, N. L.; Wiendl, F. M.

1995-02-01

Ionizing radiation has been used to treat poultry to remove harmful microorganisms, mainly Salmonella, which contaminates chicken, goose and other fresh and frozen poultry. This microorganism is sensitive to low dose radiation. Thus, irradiating these foods with doses between 1 to 7 kGy results in a large reduction of bacteria. Since it is necessary to determine whether irradiation has occurred and to what extend, this work studied the signal produced by ionizing radiation within the hard crystalline matrix of chicken's bone to establish a control method. Chicken's drumsticks were irradiated and bones separated from flesh were lyophilized and milled. ESR spectrum was then obtained. The ESR signal increased linearly with dose over the range 0.25 to 8.0 kGy. Free radicals evaluated during 30 days after irradiation showed stable in this period.

Iodine Prophylaxis in the Case of Nuclear Accident.

PubMed

Zbigniew, Szybinski

2017-01-01

On 26th April, 1986 the greatest accident of nuclear plant in Czernobyl occured and isotopes with high percentage of release were erupted: 33-Xe, 131-I, 132-Te, 134-Cs and 137-Cs. The radioactivity of the isotopes was very high - for instance: 33-Xe 6500 PBq, 131-I 1760 PBq. Rest of the 15 isotopes represented similar radioactivity with shorter percentage of release. The most exposed group of people were 237 liquidators, and 11600 people living around had to be evacuated when the limit dose for a person (5mSv) was crossed. Ionizing radiation on the molecular level produces high energy radicals, water radiolysis and ionization of the atoms leading to damage of the enzymes activity centers and receptors, cell membranes DNA, intracellular lysosomes, and especially important for ATP synthesis - mitochondria. These destructions lead to tissue and organs damage. The aim of this article is the presentation of the protective property of iodine application in the case of nuclear accident. In Poland at that time, effective iodine prophylaxis did not exist. In the face of such exposition, a special Governement Commission was appointed. When permissioned maximal dose for children and adolescents 50mSv appeared in some areas of the country, the Commission made a decision about obligatory administration of a single pharmacological dose of potassium iodide for all children and adolescents till age 16. No relevant recent patents were available for this WHO report. In this way, the dose of 131-I to thyroid for inhabitants in high, moderated, and low contaminated regions were reduced by about 45%. However, from 1987 to 1997 increase in prevalence of the differentiated thyroid cancer in adults in Polish population especially in women over 40 years old in the southern part of Poland was observed. Actually in European countries work 185 nuclear power plants and to 2045 another 100 is planned. In 1999, WHO issued recommendations on iodine prophylaxis in the case of nuclear accident. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Effects of the Effect of Ultra High Frequency Mobile Phone Radiation on Human Health.

PubMed

Moradi, Mosa; Naghdi, Nasrollah; Hemmati, Hamidreza; Asadi-Samani, Majid; Bahmani, Mahmoud

2016-05-01

Public and occupational exposure to electromagnetic fields due to the growing trend of electronic devices may cause adverse effects on human health. This paper describes the risk of mutation and sexual trauma and infertility in masculine sexual cell by mobile phone radiations. In this study, we measured the emitted dose from a radiofrequency device, such as switching high voltage at different frequencies using a scintillation detector. The switching high voltage power supply (HVPS) was built for the Single Photon Emission Computed Tomography (SPECT) system. For radiation dosimetry, we used an ALNOR scintillator that can measure gamma radiation. The simulation was performed by MATLAB software, and data from the International Commission on Non-Ionizing Radiation Protection (ICNIRP) were used to verify the simulation. We investigated the risks that result from the waves, according to a report by International Commission on Non Ionizing Radiation Protection (ICNIRP), to every organ of the body is defined by the beam and electromagnetic radiation from this electronic device on people. The results showed that the maximum personal dose over a 15-min period working at the mentioned HVPS did not exceed 0.31 μSV/h (with an aluminum shield). So, according to other sources of radiation, continuous working time of the system should not be more than 10 hours. Finally, a characteristic curve for secure working with modules at different frequencies was reported. The RF input signal to the body for maximum penetration depth (δ) and electromagnetic energy absorption rate (SAR) of biological tissue were obtained for each tissue. The results of this study and International Commission of Non Ionization Radiation Protection (ICNIRP) reports showed the people who spend more than 50 minutes a day using a cell phone could have early dementia or other thermal damage due to the burning of glucose in the brain.

Stereoselective quantification of methadone and a d(6)-labeled isotopomer using high performance liquid chromatography-atmospheric pressure chemical ionization mass-spectrometry: application to a pharmacokinetic study in a methadone maintained subject.

PubMed

Foster, David J R; Morton, Erin B; Heinkele, Georg; Mürdter, Thomas E; Somogyi, Andrew A

2006-08-01

There is evidence that the apparent oral clearance of rac-methadone is induced during the early phase of methadone maintenance treatment. However, it is not known if this is due to changes in bioavailability or if this phenomenon is stereoselective. This knowledge can be obtained by administering a dose of stable-labeled methadone at selected times during ongoing treatment. Therefore, the authors developed a stereoselective high performance liquid chromatography-atmospheric pressure chemical ionization mass-spectrometry assay for the quantification of the enantiomers of methadone and a d(6)-labeled isotopomer. The compounds were quantified in a single assay after liquid-liquid extraction and stereoselective high performance liquid chromatograph with atmospheric pressure chemical ionization-mass spectrometry detection. The following ions were monitored: m/z 310.15 for unlabeled methadone; m/z 316.15 for methadone-d(6); and m/z 313.15 for the methadone-d(3) (internal standard). Calibration curves ranged from 0.5 to 75 ng/mL for each compound. Extraction recovery was approximately 80% for all analytes, without evidence of differences between the unlabeled and stable-labeled compounds or concentration dependency. Minor ion promotion was observed (<15%) but this was identical for all analytes including the d(3)-labeled internal standard, with peak area ratios in extracted samples identical to control injections. The isotopomers did not alter each others' ionisation, even at 10:1 concentration ratios, and 10-fold diluted samples were within 10% of the nominal concentration. Assay performance was acceptable, with interassay and intra-assay bias and precision <10% for all compounds, including the upper and lower limits of quantitation. In conclusion, the assay was successfully applied to quantify the concentration of the methadone enantiomers of both orally administered unlabeled methadone and an intravenous 5 mg dose of methadone-d(6) in a patient receiving chronic oral methadone maintenance therapy.

Effect of Ultra High Frequency Mobile Phone Radiation on Human Health

PubMed Central

Moradi, Mosa; Naghdi, Nasrollah; Hemmati, Hamidreza; Asadi-Samani, Majid; Bahmani, Mahmoud

2016-01-01

Introduction Public and occupational exposure to electromagnetic fields due to the growing trend of electronic devices may cause adverse effects on human health. This paper describes the risk of mutation and sexual trauma and infertility in masculine sexual cell by mobile phone radiations. Methods In this study, we measured the emitted dose from a radiofrequency device, such as switching high voltage at different frequencies using a scintillation detector. The switching high voltage power supply (HVPS) was built for the Single Photon Emission Computed Tomography (SPECT) system. For radiation dosimetry, we used an ALNOR scintillator that can measure gamma radiation. The simulation was performed by MATLAB software, and data from the International Commission on Non-Ionizing Radiation Protection (ICNIRP) were used to verify the simulation. Results We investigated the risks that result from the waves, according to a report by International Commission on Non Ionizing Radiation Protection (ICNIRP), to every organ of the body is defined by the beam and electromagnetic radiation from this electronic device on people. The results showed that the maximum personal dose over a 15-min period working at the mentioned HVPS did not exceed 0.31 μSV/h (with an aluminum shield). So, according to other sources of radiation, continuous working time of the system should not be more than 10 hours. Finally, a characteristic curve for secure working with modules at different frequencies was reported. The RF input signal to the body for maximum penetration depth (δ) and electromagnetic energy absorption rate (SAR) of biological tissue were obtained for each tissue. Conclusion The results of this study and International Commission of Non Ionization Radiation Protection (ICNIRP) reports showed the people who spend more than 50 minutes a day using a cell phone could have early dementia or other thermal damage due to the burning of glucose in the brain. PMID:27382458

Low and high dose rate heavy ion radiation-induced intestinal and colonic tumorigenesis in APC1638N/+ mice

NASA Astrophysics Data System (ADS)

Suman, Shubhankar; Kumar, Santosh; Moon, Bo-Hyun; Fornace, Albert J.; Datta, Kamal

2017-05-01

Ionizing radiation (IR) is a recognized risk factor for colorectal cancer (CRC) and astronauts undertaking long duration space missions are expected to receive IR doses in excess of permissible limits with implications for colorectal carcinogenesis. Exposure to IR in outer space occurs at low doses and dose rates, and energetic heavy ions due to their high linear energy transfer (high-LET) characteristics remain a major concern for CRC risk in astronauts. Previously, we have demonstrated that intestinal tumorigenesis in a mouse model (APC1638N/+) of human colorectal cancer was significantly higher after exposure to high dose rate energetic heavy ions relative to low-LET γ radiation. The purpose of the current study was to compare intestinal tumorigenesis in APC1638N/+ mice after exposure to energetic heavy ions at high (50 cGy/min) and relatively low (0.33 cGy/min) dose rate. Male and female mice (6-8 weeks old) were exposed to either 10 or 50 cGy of 28Si (energy: 300 MeV/n; LET: 70 keV/μm) or 56Fe (energy: 1000 MeV/n; LET: 148 keV/μm) ions at NASA Space Radiation Laboratory in Brookhaven National Laboratory. Mice (n = 20 mice/group) were euthanized and intestinal and colon tumor frequency and size were counted 150 days after radiation exposure. Intestinal tumorigenesis in male mice exposed to 56Fe was similar for high and low dose rate exposures. Although male mice showed a decreasing trend at low dose rate relative to high dose rate exposures, the differences in tumor frequency between the two types of exposures were not statistically significant after 28Si radiation. In female mice, intestinal tumor frequency was similar for both radiation type and dose rates tested. In both male and female mice intestinal tumor size was not different after high and low dose rate radiation exposures. Colon tumor frequency in male and female mice after high and low dose rate energetic heavy ions was also not significantly different. In conclusion, intestinal and colonic tumor frequency and size was similar irrespective of energetic heavy ion radiation dose rate suggesting that carcinogenic potential of energetic heavy ions is independent of dose rate.

Prevention of Transfusion-Associated Graft-versus-Host Disease by Irradiation: Technical Aspect of a New Ferrous Sulphate Dosimetric System

PubMed Central

Del Lama, Lucas Sacchini; de Góes, Evamberto Garcia; Petchevist, Paulo César Dias; Moretto, Edson Lara; Borges, José Carlos; Covas, Dimas Tadeu; de Almeida, Adelaide

2013-01-01

Irradiation of whole blood and blood components before transfusion is currently the only accepted method to prevent Transfusion-Associated Graft-Versus-Host-Disease (TA-GVHD). However, choosing the appropriate technique to determine the dosimetric parameters associated with blood irradiation remains an issue. We propose a dosimetric system based on the standard Fricke Xylenol Gel (FXG) dosimeter and an appropriate phantom. The modified dosimeter was previously calibrated using a 60Co teletherapy unit and its validation was accomplished with a 137Cs blood irradiator. An ionization chamber, standard FXG, radiochromic film and thermoluminescent dosimeters (TLDs) were used as reference dosimeters to determine the dose response and dose rate of the 60Co unit. The dose distributions in a blood irradiator were determined with the modified FXG, the radiochromic film, and measurements by TLD dosimeters. A linear response for absorbed doses up to 54 Gy was obtained with our system. Additionally, the dose rate uncertainties carried out with gel dosimetry were lower than 5% and differences lower than 4% were noted when the absorbed dose responses were compared with ionization chamber, film and TLDs. PMID:23762345

The validation of tomotherapy dose calculations in low-density lung media

NASA Astrophysics Data System (ADS)

Chaudhari, Summer R.; Pechenaya, Olga L.; Goddu, S. Murty; Mutic, Sasa; Rangaraj, Dharanipathy; Bradley, Jeffrey D.; Low, Daniel

2009-04-01

The dose-calculation accuracy of the tomotherapy Hi-Art II® (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values <=1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

The validation of tomotherapy dose calculations in low-density lung media.

PubMed

Chaudhari, Summer R; Pechenaya, Olga L; Goddu, S Murty; Mutic, Sasa; Rangaraj, Dharanipathy; Bradley, Jeffrey D; Low, Daniel

2009-04-21

The dose-calculation accuracy of the tomotherapy Hi-Art II(R) (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values < or =1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

Effects of ionizing radiation on DNA methylation: from experimental biology to clinical applications.

PubMed

Miousse, Isabelle R; Kutanzi, Kristy R; Koturbash, Igor

2017-05-01

Ionizing radiation (IR) is a ubiquitous environmental stressor with genotoxic and epigenotoxic capabilities. Terrestrial IR, predominantly a low-linear energy transfer (LET) radiation, is being widely utilized in medicine, as well as in multiple industrial applications. Additionally, an interest in understanding the effects of high-LET irradiation is emerging due to the potential of exposure during space missions and the growing utilization of high-LET radiation in medicine. In this review, we summarize the current knowledge of the effects of IR on DNA methylation, a key epigenetic mechanism regulating the expression of genetic information. We discuss global, repetitive elements and gene-specific DNA methylation in light of exposure to high and low doses of high- or low-LET IR, fractionated IR exposure, and bystander effects. Finally, we describe the mechanisms of IR-induced alterations to DNA methylation and discuss ways in which that understanding can be applied clinically, including utilization of DNA methylation as a predictor of response to radiotherapy and in the manipulation of DNA methylation patterns for tumor radiosensitization.

GONAD DOSES IN THE X IRRADIATION OF SOME SO-CALLED MILD ILLNESSES (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glauner, R.; Messner, D.; Thelen, P.O.

1958-10-01

Measurements of gonad doses were carried out on men and women using ionization chambers. In women the measurements were made in the vagina. Gonad doses were measured in patients who received x-ray therapy for puerperal mastitis, sweat gland abscesses in the axilla, and furunculi of the face. The conditions of irradiation, as well as the single and total doses, are briefiy discussed. Various means of reducing gonad dose are discussed in detail. (auth)

Compendium of Single-Event Latchup and Total Ionizing Dose Test Results of Commercial Analog to Digital Converters

NASA Technical Reports Server (NTRS)

Irom, Farokh; Agarwal, Shri G.

2012-01-01

This paper reports single-event latchup and total dose results for a variety of analog to digital converters targeted for possible use in NASA spacecraft's. The compendium covers devices tested over the last 15 years.

What happens when spins meet for ionizing radiation dosimetry?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavoni, Juliana F.; Baffa, Oswaldo, E-mail: baffa@usp.br; Neves-Junior, Wellington F. P.

2016-07-07

Electron spin resonance (ESR) and magnetic resonance imaging (MRI) can be used to measure radiation dose deposited in different milieu through its effects. Radiation can break chemical bonds and if they produce stable free radicals, ESR can measure their concentration through their spins and a dose can be inferred. Ionizing radiation can also promote polymerization and in this case proton relaxation times can be measured and an image weighed by T2 can be produced giving spatial information about dose. A review of the basics of these applications is presented concluding with an end-to-end test using a composite Gel-Alanine phantom tomore » validate 3-dimensionally dose distribution delivered in a simulation of Volume Modulated Arch Therapy on the simultaneous treatment of multiple brain metastases. The results obtained with the gel and alanine dosimeters are consistent with the expected by the treatment planning system, showing the potential of this multidosimetric approach and validating dosimetrically the multiple brain metastases treatment using VMAT.« less

What happens when spins meet for ionizing radiation dosimetry?

NASA Astrophysics Data System (ADS)

Pavoni, Juliana F.; Neves-Junior, Wellington F. P.; Baffa, Oswaldo

2016-07-01

Electron spin resonance (ESR) and magnetic resonance imaging (MRI) can be used to measure radiation dose deposited in different milieu through its effects. Radiation can break chemical bonds and if they produce stable free radicals, ESR can measure their concentration through their spins and a dose can be inferred. Ionizing radiation can also promote polymerization and in this case proton relaxation times can be measured and an image weighed by T2 can be produced giving spatial information about dose. A review of the basics of these applications is presented concluding with an end-to-end test using a composite Gel-Alanine phantom to validate 3-dimensionally dose distribution delivered in a simulation of Volume Modulated Arch Therapy on the simultaneous treatment of multiple brain metastases. The results obtained with the gel and alanine dosimeters are consistent with the expected by the treatment planning system, showing the potential of this multidosimetric approach and validating dosimetrically the multiple brain metastases treatment using VMAT.

Evaluation of GaAs low noise and power MMIC technologies to neutron, ionizing dose and dose rate effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Derewonko, H.; Bosella, A.; Pataut, G.

1996-06-01

An evaluation program of Thomson CSF-TCS GaAs low noise and power MMIC technologies to 1 MeV equivalent neutron fluence levels, up to 1 {times} 10{sup 15} n/cm{sup 2}, ionizing 1.17--1.33 MeV CO{sup 60} dose levels in excess of 200 Mrad(GaAs) and dose rate levels reaching 1.89 {times} 10{sup 11} rad(GaAs)/s is presented in terms of proper components and parameter choices, DC/RF electrical measurements and test methods under irradiation. Experimental results are explained together with drift analyses of electrical parameters that have determined threshold limits of component degradations. Modelling the effects of radiation on GaAs components relies on degradation analysis ofmore » active layer which appears to be the most sensitive factor. MMICs degradation under neutron fluence was simulated from irradiated FET data. Finally, based on sensitivity of technological parameters, rad-hard design including material, technology and MMIC design enhancement is discussed.« less

Experimental and Monte Carlo evaluation of Eclipse treatment planning system for effects on dose distribution of the hip prostheses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Çatlı, Serap, E-mail: serapcatli@hotmail.com; Tanır, Güneş

2013-10-01

The present study aimed to investigate the effects of titanium, titanium alloy, and stainless steel hip prostheses on dose distribution based on the Monte Carlo simulation method, as well as the accuracy of the Eclipse treatment planning system (TPS) at 6 and 18 MV photon energies. In the present study the pencil beam convolution (PBC) method implemented in the Eclipse TPS was compared to the Monte Carlo method and ionization chamber measurements. The present findings show that if high-Z material is used in prosthesis, large dose changes can occur due to scattering. The variance in dose observed in the presentmore » study was dependent on material type, density, and atomic number, as well as photon energy; as photon energy increased back scattering decreased. The dose perturbation effect of hip prostheses was significant and could not be predicted accurately by the PBC method for hip prostheses. The findings show that for accurate dose calculation the Monte Carlo-based TPS should be used in patients with hip prostheses.« less

Low dose/low fluence ionizing radiation-induced biological effects: The role of intercellular communication and oxidative metabolism

NASA Astrophysics Data System (ADS)

Azzam, Edouard

Mechanistic investigations have been considered critical to understanding the health risks of exposure to ionizing radiation. To gain greater insight in the biological effects of exposure to low dose/low fluence space radiations with different linear energy transfer (LET) properties, we examined short and long-term biological responses to energetic protons and high charge (Z) and high energy (E) ions (HZE particles) in human cells maintained in culture and in targeted and non-targeted tissues of irradiated rodents. Particular focus of the studies has been on mod-ulation of gene expression, proliferative capacity, induction of DNA damage and perturbations in oxidative metabolism. Exposure to mean doses of 1000 MeV/nucleon iron ions, by which a small to moderate proportion of cells in an exposed population is targeted through the nucleus by an HZE particle, induced stressful effects in the irradiated and non-irradiated cells in the population. Direct intercellular communication via gap-junctions was a primary mediator of the propagation of stressful effects from irradiated to non-irradiated cells. Compromised prolif-erative capacity, elevated level of DNA damage and oxidative stress evaluated by measurements of protein carbonylation, lipid peroxidation and activity of metabolic enzymes persisted in the progeny of irradiated and non-irradiated cells. In contrast, progeny of cells exposed to high or low doses from 150-1000 MeV protons retained the ability to form colonies and harbored similar levels of micronuclei, a surrogate form of DNA damage, as control, which correlated with normal reactive oxygen species (ROS) levels. Importantly, a significant increase in the spontaneous neoplastic transformation frequency was observed in progeny of bystander mouse embryo fibroblasts (MEFs) co-cultured with MEFs irradiated with energetic iron ions but not protons. Of particular significance, stressful effects were detected in non-targeted tissues of rats that received partial body irradiation, 20 months earlier, from low mean doses of HZE particles. These effects were associated with disruption of mitochondrial function in the non-irradiated tissues and in modulation of immune cell populations. Collectively, our data support the concept that the response of the organism to high LET radiations involves irradiated and non-irradiated cells/tissues and is associated with changes in several physiological functions. Supported by the US National Aeronautics and Space Administration

The New Radiobiology: Returning to Our Roots

PubMed Central

Ulsh, Brant A.

2012-01-01

In 2005, two expert advisory bodies examined the evidence on the effects of low doses of ionizing radiation. The U.S. National Research Council concluded that current scientific evidence is consistent with the linear no-threshold dose-response relationship (NRCNA 2005) while the French National Academies of Science and Medicine concluded the opposite (Aurengo et al. 2005). These contradictory conclusions may stem in part from an emphasis on epidemiological data (a “top down” approach) versus an emphasis on biological mechanisms (a “bottom up” approach). In this paper, the strengths and limitations of the top down and bottom up approaches are discussed, and proposals for strengthening and reconciling them are suggested. The past seven years since these two reports were published have yielded increasing evidence of nonlinear responses of biological systems to low radiation doses delivered at low dose-rates. This growing body of evidence is casting ever more doubt on the extrapolation of risks observed at high doses and dose-rates to estimate risks associated with typical environmental and occupational exposures. This paper compares current evidence on low dose, low dose-rate effects against objective criteria of causation. Finally, some questions for a post-LNT world are posed. PMID:23304107

LM193 Dual Differential Comparator Total Ionizing Dose Test Report

NASA Technical Reports Server (NTRS)

Topper, Alyson; Forney, James; Campola, Michael

2017-01-01

The purpose of this test was to characterize the flight lot of Texas Instruments' LM193 (flight part number is 5962-9452601Q2A) for total dose response. This test served as the radiation lot acceptance test (RLAT) for the lot date code (LDC) tested. Low dose rate (LDR) irradiations were performed in this test so that the device susceptibility to enhanced low dose rate sensitivity (ELDRS) was determined.

The reliability studies of nano-engineered SiGe HBTs using Pelletron accelerator

NASA Astrophysics Data System (ADS)

Prakash, A. P. Gnana; Praveen, K. C.; Pushpa, N.; Cressler, John D.

2015-05-01

The effects of high energy ions on the electrical characteristics of silicon-germanium heterojunction bipolar transistors (SiGe HBTs) were studied in the total dose of ranging from 600 krad to 100 Mrad (Si). The two generations (50 GHz and 200 GHz) of SiGe HBTs were exposed to 50 MeV lithium, 75 MeV boron and 100 MeV oxygen ions. The electrical characteristics of SiGe HBTs were studied before and after irradiation. The SiGe HBTs were exposed to 60Co gamma radiation in the same total dose. The results are systematically compared in order to understand the interaction of ions and ionizing radiation with SiGe HBTs.

Methods and compositions for protection of cells and tissues from computed tomography radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grdina, David J.

Described are methods for preventing or inhibiting genomic instability and in cells affected by diagnostic radiology procedures employing ionizing radiation. Embodiments include methods of preventing or inhibiting genomic instability and in cells affected by computed tomography (CT) radiation. Subjects receiving ionizing radiation may be those persons suspected of having cancer, or cancer patients having received or currently receiving cancer therapy, and or those patients having received previous ionizing radiation, including those who are approaching or have exceeded the recommended total radiation dose for a person.

Risk of occupational radiation-induced cataract in medical workers.

PubMed

Milacic, Snezana

2009-01-01

ionizing radiation on the lens of the eye can produce a progressive cataract. Small cumulative doses, over a long time period, can produce adverse effects on the professional capabilities of health workers in the ionizing radiation zone. The aim of this study was to ascertain whether occupational exposure to low levels of ionizing radiation can cause an increase in prevalence of cataract. We compared a group with occupational cataract, consisting of 115 health workers in the ionizing radiation zone, and two control groups: a group of 100 health-care workers in the ionizing radiation zone, with a higher incidence of chromosomal aberrations, but without cataract; and another control group of 26 health-care workers with cataract, outside the zone; all risk factors for the development of cataract were considered: age, sex, diference in profession, duration of occupational exposure, years of service, level of blood sugar, blood pressure, arrhythmias, etc. A more significant incidence of cataract was found in workers in the ionizing radiation zone, where the relative risk was 4.6; p < 0.01. Radiology technicians showed the highest prevalence (63.5%), while physicians-radiologists and pneumologists were second (15.7%) and third (10.3%) respectively; nurses showed a 3.5% incidence and nuclear medicine department workers showed an incidence of only 1.7%. Other risk factors had an effect on the development of cataract (p < 0.05). Occupational exposure to low doses of ionizing radiation, together with other risk factors, is a significant cofactor in the occurrence of cataract as an occupational disease among x-ray exposed health care workers. The categories most at risk are radiology technicians,followed by radiologists.

[Dosimetric system for assessing doses received by people occupationally exposed to external sources of ionizing radiation].

PubMed

Brodecki, Marcin; Domienik, Joanna U; Zmyślony, Marek

2012-01-01

The current system of dosimetric quantities has been defined by the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU). Complexity of the system implies the physical nature of ionizing radiation, resulting from the presence of different types of radiation of different ionization capabilities, as well as the individual radiation sensitivity of biological material exposed. According to the latest recommendations, there are three types of dosimeter quantities relevant to radiation protection and radiological assessment of occupational exposure. These are the basic quantities, safety quantities and operational quantities. Dose limits for occupational exposure relate directly to the protection quantities, i.e. the equivalent dose and effective dose, while these quantities are practically unmeasurable in real measurement conditions. For this reason, in the system of dosimetric quantities directly measurable operating volumes were defined. They represent equivalents of the protection quantities that allow for a reliable assessment of equivalent and effective dose by conducting routine monitoring of occupational exposure. This paper presents the characteristics of these quantities, their relationships and importance in assessing individual effects of radiation. Also the methods for their implementation in personal and environmental dosimetry were showcased. The material contained in the article is a compendium of essential information about dosimetric quantities with reference to the contemporary requirements of the law, including the changed annual occupational exposure limit for the lens of the eye. The material is especially addressed to those responsible for dosimetry monitoring in the workplace, radiation protection inspectors and occupational health physicians.

Estimation of dose rates at the entrance surface for exposure scenarios of total body irradiation using MCNPX code

NASA Astrophysics Data System (ADS)

Cunha, J. S.; Cavalcante, F. R.; Souza, S. O.; Souza, D. N.; Santos, W. S.; Carvalho Júnior, A. B.

2017-11-01

One of the main criteria that must be held in Total Body Irradiation (TBI) is the uniformity of dose in the body. In TBI procedures the certification that the prescribed doses are absorbed in organs is made with dosimeters positioned on the patient skin. In this work, we modelled TBI scenarios in the MCNPX code to estimate the entrance dose rate in the skin for comparison and validation of simulations with experimental measurements from literature. Dose rates were estimated simulating an ionization chamber laterally positioned on thorax, abdomen, leg and thigh. Four exposure scenarios were simulated: ionization chamber (S1), TBI room (S2), and patient represented by hybrid phantom (S3) and water stylized phantom (S4) in sitting posture. The posture of the patient in experimental work was better represented by S4 compared with hybrid phantom, and this led to minimum and maximum percentage differences of 1.31% and 6.25% to experimental measurements for thorax and thigh regions, respectively. As for all simulations reported here the percentage differences in the estimated dose rates were less than 10%, we considered that the obtained results are consistent with experimental measurements and the modelled scenarios are suitable to estimate the absorbed dose in organs during TBI procedure.

Hemopoietic Response to Low Dose-Rates of Ionizing Radiation Shows Stem Cell Tolerance and Adaptation

PubMed Central

Fliedner, Theodor M.; Graessle, Dieter H.; Meineke, Viktor; Feinendegen, Ludwig E.

2012-01-01

Chronic exposure of mammals to low dose-rates of ionizing radiation affects proliferating cell systems as a function of both dose-rate and the total dose accumulated. The lower the dose-rate the higher needs to be the total dose for a deterministic effect, i.e., tissue reaction to appear. Stem cells provide for proliferating, maturing and functional cells. Stem cells usually are particularly radiosensitive and damage to them may propagate to cause failure of functional cells. The paper revisits 1) medical histories with emphasis on the hemopoietic system of the victims of ten accidental chronic radiation exposures, 2) published hematological findings of long-term chronically gamma-irradiated rodents, and 3) such findings in dogs chronically exposed in large life-span studies. The data are consistent with the hypothesis that hemopoietic stem and early progenitor cells have the capacity to tolerate and adapt to being repetitively hit by energy deposition events. The data are compatible with the “injured stem cell hypothesis”, stating that radiation–injured stem cells, depending on dose-rate, may continue to deliver clones of functional cells that maintain homeostasis of hemopoiesis throughout life. Further studies perhaps on separated hemopoietic stem cells may unravel the molecular-biology mechanisms causing radiation tolerance and adaptation. PMID:23304110

Mechanisms and biological importance of photon-induced bystander responses: do they have an impact on low-dose radiation responses

PubMed Central

Tomita, Masanori; Maeda, Munetoshi

2015-01-01

Abstract Elucidating the biological effect of low linear energy transfer (LET), low-dose and/or low-dose-rate ionizing radiation is essential in ensuring radiation safety. Over the past two decades, non-targeted effects, which are not only a direct consequence of radiation-induced initial lesions produced in cellular DNA but also of intra- and inter-cellular communications involving both targeted and non-targeted cells, have been reported and are currently defining a new paradigm in radiation biology. These effects include radiation-induced adaptive response, low-dose hypersensitivity, genomic instability, and radiation-induced bystander response (RIBR). RIBR is generally defined as a cellular response that is induced in non-irradiated cells that receive bystander signals from directly irradiated cells. RIBR could thus play an important biological role in low-dose irradiation conditions. However, this suggestion was mainly based on findings obtained using high-LET charged-particle radiations. The human population (especially the Japanese, who are exposed to lower doses of radon than the world average) is more frequently exposed to low-LET photons (X-rays or γ-rays) than to high-LET charged-particle radiation on a daily basis. There are currently a growing number of reports describing a distinguishing feature between photon-induced bystander response and high-LET RIBR. In particular, photon-induced bystander response is strongly influenced by irradiation dose, the irradiated region of the targeted cells, and p53 status. The present review focuses on the photon-induced bystander response, and discusses its impact on the low-dose radiation effect. PMID:25361549

Mechanism of action of ionizing radiation on hexokinase and cholinesterase activity in the rat brain, in the presence of altered function of M-cholinergic structures. [X radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khripchenko, I.P.; Kukulyanskaya, M.F.; Markina, V.L.

1977-01-01

Data are submitted on activity of hexokinase and isozymes thereof, and cholinesterase in subcellular fractions of the brain in the case of inhibition and stimulation of M-cholinoreactive structures under the influence of a relatively small dose, 40 R, of ionizing radiation.

Space radiation effects on plant and mammalian cells

NASA Astrophysics Data System (ADS)

Arena, C.; De Micco, V.; Macaeva, E.; Quintens, R.

2014-11-01

The study of the effects of ionizing radiation on organisms is related to different research aims. The current review emphasizes the studies on the effects of different doses of sparsely and densely ionizing radiation on living organisms, with the final purpose of highlighting specific and common effects of space radiation in mammals and plants. This topic is extremely relevant in the context of radiation protection from space environment. The response of different organisms to ionizing radiation depends on the radiation quality/dose and/or the intrinsic characteristics of the living system. Macromolecules, in particular DNA, are the critical targets of radiation, even if there is a strong difference between damages encountered by plant and mammalian cells. The differences in structure and metabolism between the two cell types are responsible for the higher resistance of the plant cell compared with its animal counterpart. In this review, we report some recent findings from studies performed in Space or on Earth, simulating space-like levels of radiation with ground-based facilities, to understand the effect of ionizing radiation on mammalian and plant cells. In particular, our attention is focused on genetic alterations and repair mechanisms in mammalian cells and on structures and mechanisms conferring radioresistance to plant cells.

Effects of radiation type and delivery mode on a radioresistant eukaryote Cryptococcus neoformans

PubMed Central

Shuryak, Igor; Bryan, Ruth A.; Broitman, Jack; Marino, Stephen A.; Morgenstern, Alfred; Apostolidis, Christos; Dadachova, Ekaterina

2015-01-01

Introduction Most research on radioresistant fungi, particularly on human pathogens such as Cryptococcus neoformans, involves sparsely-ionizing radiation. Consequently, fungal responses to densely-ionizing radiation, which can be harnessed to treat life-threatening fungal infections, remain incompletely understood. Methods We addressed this issue by quantifying and comparing the effects of densely-ionizing α-particles (delivered either by external beam or by 213Bi-labeled monoclonal antibodies), and sparsely-ionizing 137Cs γ-rays, on Cryptococus neoformans. Results The best-fit linear-quadratic parameters for clonogenic survival were the following: α=0.24×10−2 Gy−1 for γ-rays and 1.07×10−2 Gy−1 for external-beam α-particles, and β=1.44×10−5 Gy−2 for both radiation types. Fungal cell killing by radiolabeled antibodies was consistent with predictions based on the α-particle dose to the cell nucleus and the linear-quadratic parameters for external-beam α-particles. The estimated RBE (for α-particles vs γ-rays) at low doses was 4.47 for the initial portion of the α-particle track, and 7.66 for the Bragg peak. Non-radiological antibody effects accounted for up to 23% of cell death. Conclusions These results quantify the degree of C. neoformans resistance to densely-ionizing radiations, and show how this resistance can be overcome with fungus-specific radiolabeled antibodies. PMID:25800676

Apoptotic activity of 5-fluorouracil in breast cancer cells transformed by low doses of ionizing α-particle radiation.

PubMed

Ponce-Cusi, Richard; Calaf, Gloria M

2016-02-01

Globally, breast cancer in women is the leading cause of cancer death. This fact has generated an interest to obtain insight into breast tumorigenesis and also to develop drugs to control the disease. Ras is a proto-oncogene that is activated as a response to extracellular signals. As a member of the Ras GTPase superfamily, Rho-A is an oncogenic and a critical component of signaling pathways leading to downstream gene regulation. In chemotherapy, apoptosis is the predominant mechanism by which cancer cells die. However, even when the apoptotic machinery remains intact, survival signaling may antagonize the cell death by signals. The aim of this study was to evaluate 5-fluorouracil (5-FU) in cells transformed by low doses of ionizing α-particle radiation, in breast cancer cell lines on these genes, as well as apoptotic activity. We used two cell lines from an in vitro experimental breast cancer model. The MCF-10F and Tumor2 cell lines. MCF-10F was exposed to low doses of high linear energy transfer (LET) α-particles radiation (150 keV/µm). Tumor2, is a malignant and tumorigenic cell line obtained from Alpha5 (60cGy+E/60cGy+E) injected into the nude mice. Results indicated that 5-FU decreased H-ras, Rho-A, p53, Stat1 and increased Bax gene expression in Tumor2 and decreased Rac1, Rho-A, NF-κB and increased Bax and caspase-3 protein expression in Tumor2. 5-FU decreased H-ras, Bcl-xL and NF-κB and increased Bax gene expression. 5-FU decreased Rac1, Rho-A protein expression and increased Bax and caspase-3 protein expression in MDA-MB-231. Flow cytometry indicated 21.5% of cell death in the control MCF-10F and 80% in Tumor2 cell lines. It can be concluded that 5-FU may exert apoptotic activity in breast cancer cells transformed by low doses of ionizing α-particles in vitro regulating genes of Ras family and related to apoptosis such as Bax, Bcl-xL and NF-κB expression.

Live-cell imaging to detect phosphatidylserine externalization in brain endothelial cells exposed to ionizing radiation: implications for the treatment of brain arteriovenous malformations.

PubMed

Zhao, Zhenjun; Johnson, Michael S; Chen, Biyi; Grace, Michael; Ukath, Jaysree; Lee, Vivienne S; McRobb, Lucinda S; Sedger, Lisa M; Stoodley, Marcus A

2016-06-01

OBJECT Stereotactic radiosurgery (SRS) is an established intervention for brain arteriovenous malformations (AVMs). The processes of AVM vessel occlusion after SRS are poorly understood. To improve SRS efficacy, it is important to understand the cellular response of blood vessels to radiation. The molecular changes on the surface of AVM endothelial cells after irradiation may also be used for vascular targeting. This study investigates radiation-induced externalization of phosphatidylserine (PS) on endothelial cells using live-cell imaging. METHODS An immortalized cell line generated from mouse brain endothelium, bEnd.3 cells, was cultured and irradiated at different radiation doses using a linear accelerator. PS externalization in the cells was subsequently visualized using polarity-sensitive indicator of viability and apoptosis (pSIVA)-IANBD, a polarity-sensitive probe. Live-cell imaging was used to monitor PS externalization in real time. The effects of radiation on the cell cycle of bEnd.3 cells were also examined by flow cytometry. RESULTS Ionizing radiation effects are dose dependent. Reduction in the cell proliferation rate was observed after exposure to 5 Gy radiation, whereas higher radiation doses (15 Gy and 25 Gy) totally inhibited proliferation. In comparison with cells treated with sham radiation, the irradiated cells showed distinct pseudopodial elongation with little or no spreading of the cell body. The percentages of pSIVA-positive cells were significantly higher (p = 0.04) 24 hours after treatment in the cultures that received 25- and 15-Gy doses of radiation. This effect was sustained until the end of the experiment (3 days). Radiation at 5 Gy did not induce significant PS externalization compared with the sham-radiation controls at any time points (p > 0.15). Flow cytometric analysis data indicate that irradiation induced growth arrest of bEnd.3 cells, with cells accumulating in the G2 phase of the cell cycle. CONCLUSIONS Ionizing radiation causes remarkable cellular changes in endothelial cells. Significant PS externalization is induced by radiation at doses of 15 Gy or higher, concomitant with a block in the cell cycle. Radiation-induced markers/targets may have high discriminating power to be harnessed in vascular targeting for AVM treatment.

The Role of Mass Spectrometry-Based Metabolomics in Medical Countermeasures Against Radiation

PubMed Central

Patterson, Andrew D.; Lanz, Christian; Gonzalez, Frank J.; Idle, Jeffrey R.

2013-01-01

Radiation metabolomics can be defined as the global profiling of biological fluids to uncover latent, endogenous small molecules whose concentrations change in a dose-response manner following exposure to ionizing radiation. In response to the potential threat of nuclear or radiological terrorism, the Center for High-Throughput Minimally Invasive Radiation Biodosimetry (CMCR) was established to develop field-deployable biodosimeters based, in principle, on rapid analysis by mass spectrometry of readily and easily obtainable biofluids. In this review, we briefly summarize radiation biology and key events related to actual and potential nuclear disasters, discuss the important contributions the field of mass spectrometry has made to the field of radiation metabolomics, and summarize current discovery efforts to use mass spectrometry-based metabolomics to identify dose-responsive urinary constituents, and ultimately to build and deploy a noninvasive high-throughput biodosimeter. PMID:19890938

Determination of effective doses in image-guided radiation therapy system

NASA Astrophysics Data System (ADS)

Pyone, Y. Y.; Suriyapee, S.; Sanghangthum, T.; Oonsiri, S.; Tawonwong, T.

2016-03-01

The organ and effective doses in image-guided radiotherapy system are determined in this study. For 2D imaging, incident air kerma (Ki) was measured by 6cc ionization chamber with Accu-Pro dosimeter. The entrance surface air kerma (ESAK) was calculated by multiplying Ki with backscatter factor. The effective dose was calculated by multiplying ESAK with conversion coefficient. For 3D imaging, computed tomography/cone-beam dose index (CTDI/CBDI) measurements were performed by using 100mm pencil ionization chamber with Accu-Pro dosimeter. The dose index in air and in CTDI phantom from planning CT and cone- beam CT were measured. Then, effective dose was calculated by ImPACT software. The effective doses from 2D conventional simulator for anteroposterior and lateral projections were 01 and 0.02mSv for head, 0.15 and 0.16mSv for thorax, 0.22 and 0.21mSv for pelvis, respectively. The effective doses from 3D, planning CT and CBCT, were 3.3 and 0.1mSv for head, 13 and 2.4mSv for thorax and 7.2 and 4.9mSv for pelvis, respectively. Based on 30 fractions of treatment course, total effective dose (3D CT, 2D setup verification and 6 times CBCT) of head, thorax and pelvis were 3.93, 27.71 and 37.03mSv, respectively. Therefore, IGRT should be administered with significant parameters to reduce the dose.

Animal Models of Ionizing Radiation Damage

DTIC Science & Technology

1992-01-01

Phagocytosis, Bacterio/. Proc., p. 92-98, 1967. 27. Mukherjee, A.K., B. Paul, R. Strauss , and A.J. Sbarra, The Role of the Phagncyte in Host-parasite...29. Paul, B., R. Strauss , and A.J. Sbarra, The Role of the Phagocyte in Host-parasite Interactions. XVI. Effect of X-irradiation on H202 Production in...1960. 156. Madrazo, A., J. Churg , and Y. Suzuki, Radiation Nephritis. Acute Changes Following High Doses of Radiation, Am. J. Path., 54:507-527, 1969