Student perceptions of digital badges in a drug information and literature evaluation course.

PubMed

Fajiculay, Jay R; Parikh, Bhavini T; Wright, Casey V; Sheehan, Amy Heck

2017-09-01

The purpose of this article is to describe student perceptions of implementation of digital badges in a drug information and literature evaluation course. Two digital badges were developed as voluntary learning opportunities. Student perceptions were obtained through pre- and post-survey instruments consisting of selected questions from the Motivated Strategies for Learning Questionnaire. The response rate was 69% (106/153). At baseline, 53% of respondents agreed that digital badges could help them better understand course material. More students agreed they would share earned digital badges on LinkedIn (68%) than Facebook (19%). Most students who earned digital badges agreed that badges helped increase their confidence in course material (73%), focus on specific learning objectives (55%), look deeper into course competencies (64%), and were a useful adjunct to the traditional teaching method (82%). Digital badges were perceived by students as a positive adjunct to learning and may provide a novel mechanism for development of an electronic skills-based portfolio. Copyright © 2017 Elsevier Inc. All rights reserved.

Engaging Undergraduate Students in a Co-Curricular Digital Badging Platform

ERIC Educational Resources Information Center

Coleman, Jonathan D.

2018-01-01

Digital badging continues to garner attention in the educational community. What remains to be seen is how badging will interact with traditional curricular elements. While concerns have been raised about using badges as extrinsic motivators in coursework, there are alternate areas of application for digital badging. Badges may actually serve to…

Dosimeter Badge Detects Hydrazines

NASA Technical Reports Server (NTRS)

Young, Rebecca C.; Travis, Joshua C.; Moore, Gerald; Rose-Pehrsson, Susan; Carver, Patricia; Brenner, Karen

1993-01-01

Disposable dosimeter badge indicates approximate cumulative exposure to hydrazine or monomethyl hydrazine in air. Indication is change in colors of both paper tapes; one coated with para-N, N-dimethylaminobenzaldehyde. Colors of exposed tapes compared with colors on two preprinted color wheels to obtain estimate of exposure. Badges help minimize risks associated with exposure of personnel to hydrazine or monomethyl hydrazine, or suspected carcinogens. Also used as stationary monitors by taping them on walls or equipment at strategic locations.

Development of an Automated Reader for Analysis and Storage of Personnel Dosimeter Badge Data

NASA Technical Reports Server (NTRS)

Meneghelli, B. J.; Hodge, T. R.; Robinson, L. J.; Lueck, D. E.

1997-01-01

The collection and archiving of data from personnel dosimeters has become increasingly important in light of the lowered threshold limit values (TLV) for hydrazine (HZ), monomethylhydrazine (MMH), and unsymmetrical dimethylhydrazine (UDMH). The American Conference of Government Industrial Hygienists (ACGIH) lowered the TLV from 100 parts per billion (ppb) to 10 ppb and has caused increased concern over long term exposures of personnel to trace levels of these hypergols and other potentially harmful chemicals. An automated system of reading the exposure levels of personnel dosimeters and storing exposure data for subsequent evaluation has been developed. The reading of personnel dosimeter badges for exposure lo potentially harmful vapor concentrations of hydrazines or other chemicals is performed visually by comparing the color developed by the badge with a calibrated color comparator. The result obtained using visual comparisons of the developed badge color with the comparator may vary widely from user to user. The automated badge reader takes the variability out of the dosimeter reading by accurately comparing the reflectance obtained from a colored spot on the badge with a reading on the same spot prior to any exposure to chemical vapors. The observed difference between the reflectance values is used as part of a calculation of the dose value for the badge based on a stored calibration curve. The badge reader also stores bar-code data unique to each badge, as well as bar-code information on the user, as part of the permanent badge record. The start and stop exposure times for each badge are recorded and can be used as part of the calculated concentration, in ppm, for each badge logged during a recording period. The badge reader is equipped with a number of badge holders, each of which is unique to a specific type of personnel dosimeter badge. This gives the reader maximum flexibility to allow for the reading of several different types of badges. Test results of

Development of an Automated Reader for Analysis and Storage of Personnel Dosimeter Badge Data

NASA Technical Reports Server (NTRS)

Meneghelli, B. J.; Hodge, T. R.; Robinson, L. J.; Lueck, D. E.

1997-01-01

The collection and archiving of data from personnel dosimeters has become increasingly important in light of the lowered Threshold Limit Values (TLV) for HydraZine (HZ), MonoMethylHydrazine (MMH), and Unsymmetrical DiMethylHydrazine (UDMH). The American Conference of Government Industrial Hygienists (ACGIH) lowered the TLV from 100 parts per billion (ppb) to IO ppb and has caused increased concern over long term exposures of personnel to trace levels of these hypergols and other potentially harmful chemicals. An automated system of reading the exposure levels of personnel dosimeters and storing exposure data for subsequent evaluation has been developed. The reading of personnel dosimeter badges for exposure to potentially harmful vapor concentrations of hydrazines or other chemicals is performed visually by comparing the color developed by the badge with a calibrated color comparator. The result obtained using visual comparisons of the developed badge color with the comparator may vary widely from user to user. The automated badge reader takes the variability out of the dosimeter reading by accurately comparing the reflectance obtained from a colored spot on the badge with a reading on the same spot prior to any exposure to chemical vapors. The observed difference between the reflectance values is used as part of a calculation of the dose value for the badge based on a stored calibration curve. The badge reader also stores bar-code data unique to each badge, as well as bar-code information on the user, as part of the permanent badge record. The start and stop exposure times for each badge are recorded and can be used as part of the calculated concentration, in ppm, for each badge logged during a recording period. The badge reader is equipped with a number of badge holders, each of which is unique to a specific type of personnel dosimeter badge. This gives the reader maximum flexibility to allow for the reading of several different types of badges. Test results of

Survey of bisphenol a diglycidyl ether (BADGE) in canned foods.

PubMed

Summerfield, W; Goodson, A; Cooper, I

1998-10-01

2,2-Bis(4-hydroxyphenyl)propane bis(2,3-epoxypropyl) ether (BADGE) is used in the manufacture of lacquers for coating the inside of food and beverage cans. In June 1996 the EC Scientific Committee for Food temporarily increased the specific migration limit applying to BADGE to 1 mg/kg pending consideration of additional toxicological data. In order to find out if there is migration of BADGE from can coatings into foods, a 'worst case' sampling exercise has been conducted to survey those canned foods where the propensity for migration of BADGE was judged to be highest. The foods surveyed include canned fish in oil, meat and milk and, altogether, BADGE was determined in 181 retail samples. Analysis for BADGE was conducted, in duplicate, by HPLC with fluorescence detection with confirmation of BADGE identity by GC/MS analysis using selected ion monitoring. BADGE was found at levels exceeding 1 mg/kg in seven of the 15 canned anchovy samples and five of the 22 sardine samples purchased during the period September 1995-July 1996. Infrared analysis of the can coatings provided strong evidence that the higher BADGE levels found were associated with use of PVC organosol lacquers, although in some cases cans coated with organosols gave low BADGE results. For canned sardine samples found to contain greater than 0.5 mg/kg BADGE in the total contents, a replicate can was opened and separate analyses performed on the drained fish and the oil. The results clearly showed that BADGE concentrations in the oil were about 20 times higher than in the drained fish. Further samples of canned sardines and anchovies were purchased in June/July 1997 and, in all cases, BADGE levels were found to be below 1 mg/kg. In the other retail canned foods, BADGE was not detectable (DL = 0.02 mg/kg) or detected at concentrations well below the temporary SML of 1 mg/kg.

Common Badging and Access Control System (CBACS)

NASA Technical Reports Server (NTRS)

Dischinger, Portia

2005-01-01

This slide presentation presents NASA's Common Badging and Access Control System. NASA began a Smart Card implementation in January 2004. Following site surveys, it was determined that NASA's badging and access control systems required upgrades to common infrastructure in order to provide flexibly, usability, and return on investment prior to a smart card implantation. Common Badging and Access Control System (CBACS) provides the common infrastructure from which FIPS-201 compliant processes, systems, and credentials can be developed and used.

Matrix effect on leaching of Bisphenol A diglycidyl ether (BADGE) from epoxy resin based inner lacquer of aluminium tubes into semi-solid dosage forms.

PubMed

Lipke, Uwe; Haverkamp, Jan Boris; Zapf, Thomas; Lipperheide, Cornelia

2016-04-01

To study the impact of different semi-solid dosage form components on the leaching of Bisphenol A (BPA) and Bisphenol A diglycidyl ether (BADGE) from the epoxy resin-based inner lacquer of aluminium tubes, the tubes were filled with different matrix preparations and stored at an elevated temperature. Despite compliance with the European Standards EN 15348 and EN 15766 on porosity and polymerisation of internal coatings of aluminium tubes, the commercially available tubes used in the study contained an increased amount of polymerisation residues, such as unbound BPA, BADGE and BADGE derivatives in the lacquer, as determined by acetonitrile extraction. Storage of Macrogol ointments in these tubes resulted in an almost quantitative migration of the unbound polymerisation residues from the coating into the ointment. In addition, due to alterations observed in the RP-HPLC chromatograms of the matrix spiked with BADGE and BADGE derivatives it is supposed that the leachates can react with formulation components. The contamination of the medicinal product by BPA, BADGE and BADGE derivatives can be precluded by using aluminium tubes with an internal lacquer with a low degree of unbound polymerisation residues. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Digital Badges

ERIC Educational Resources Information Center

Frederiksen, Linda

2013-01-01

Unlike so much of the current vocabulary in education and technology that seems to stir more confusion than clarity, most public service librarians may already have a general idea about digital badges. As visual representations of individual accomplishments, competencies or skills that are awarded by groups, institutions, or organizations, they…

Improving and Assessing Student Hands-On Laboratory Skills through Digital Badging

ERIC Educational Resources Information Center

Hensiek, Sarah; DeKorver, Brittland K.; Harwood, Cynthia J.; Fish, Jason; O'Shea, Kevin; Towns, Marcy

2016-01-01

Building on previous success with a digital pipet badge, an evidence-centered design approach was used to develop new digital badges for measuring the volume of liquids with a buret and making a solution in a volumetric flask. These badges were implemented and assessed in two general chemistry courses. To earn the badges, students created videos…

Tweeting badges: user motivations for displaying achievement in publicly networked environments.

PubMed

Kwon, K Hazel; Halavais, Alexander; Havener, Shannon

2015-02-01

Badge systems, a common mechanism for gamification on social media platforms, provide a way for users to present their knowledge or experience to others. This study aims to contribute to the understanding of why social media users publicize their achievements in the form of online badges. Five motivational factors for badge display in public networked environments are distinguished-self-efficacy, social incentives, networked support, passing time, and inattentive sharing-and it is suggested that different badge types are associated with different motivations. System developers are advised to consider these components in their designs, applying the elements most appropriate to the communities they serve. Comparing user motivations associated with badges shared across boundaries provides a better understanding of how online badges relate to the larger social media ecosystem.

Formaldehyde Five-Day Passive Chemical Dosimeter Badge Validation Study

DTIC Science & Technology

2012-11-30

of organic carbonyl compounds ( aldehydes and ketones ) with DNPH-coated silica gel badges/cartridges in the presence of a strong acid, as a catalyst...more stringent 90-day limit of 100ppb is imminent.2 Experimental Materials Aldehyde badges (#571) were obtained from Assay Technology...Inc., Livermore, CA. This badge collects aldehydes on a glass fiber filter treated with acidified 2,4- dinitrophenylhydrazine (DNPH.) Standard field

Are There Jewish Digital Badges?: A Study of Religious Middle- and High-School Girls' Perception of an Emerging Educational Technology-Based Assessment

ERIC Educational Resources Information Center

Abramovich, Samuel

2017-01-01

For Jewish education, digital badges can provide an alternative to traditional assessments. However, the emerging research on badges suggests a complex relationship between learning opportunities, the learner, and the design of the badge. An investigation of a digital badge system at an ultra-Orthodox Jewish middle and high school for girls…

Digital Badging at The Open University: Recognition for Informal Learning

ERIC Educational Resources Information Center

Law, Patrina

2015-01-01

Awarding badges to recognise achievement is not a new development. Digital badging now offers new ways to recognise learning and motivate learners, providing evidence of skills and achievements in a variety of formal and informal settings. Badged open courses (BOCs) were piloted in various forms by the Open University (OU) in 2013 to provide a…

Opportunities and Challenges with Digital Open Badges

ERIC Educational Resources Information Center

Farmer, Tadd; West, Richard E.

2016-01-01

With increasing interest in competency and outcome-based education, and the blending of formal and informal learning, there is increasing need for credentials to match these learning paradigms. In this article, the authors discuss the benefits, challenges, and potential future directions for open digital badges--one potential alternative…

Be Prepared: The Archeology Merit Badge Is Here.

ERIC Educational Resources Information Center

Skinner, S. Alan; Saunders, Cece; Poirier, David A.; Krofina, Douglas L.; Wheat, Pam

1998-01-01

Describes the new archaeology merit badge of the Boy Scouts of America. Discusses the requirement that scouts recruit a "counselor" who is a hobbyist or working archaeologist, and outlines the duties and ethical responsibilities of such mentors. Includes the scout's requirements for earning the badge. (SV)

Badge Office Process Analysis

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

Haurykiewicz, John Paul; Dinehart, Timothy Grant; Parker, Robert Young

2016-05-12

The purpose of this process analysis was to analyze the Badge Offices’ current processes from a systems perspective and consider ways of pursuing objectives set forth by SEC-PS, namely increased customer flow (throughput) and reduced customer wait times. Information for the analysis was gathered for the project primarily through Badge Office Subject Matter Experts (SMEs), and in-person observation of prevailing processes. Using the information gathered, a process simulation model was constructed to represent current operations and allow assessment of potential process changes relative to factors mentioned previously. The overall purpose of the analysis was to provide SEC-PS management with informationmore » and recommendations to serve as a basis for additional focused study and areas for potential process improvements in the future.« less

Adding Badging to a Marketing Simulation to Increase Motivation to Learn

ERIC Educational Resources Information Center

Saxton, M. Kim

2015-01-01

Badging has become a popular tool for obtaining social recognition for personal accomplishments. This innovation describes a way to add badging to a marketing simulation to increase student motivation to achieve the simulation's goals. Assessments indicate that badging both motivates students to perform better and helps explain students' perceived…

Using Digital Badges to Organize Student Learning Opportunities

ERIC Educational Resources Information Center

Ippoliti, Cinthya; Baeza, Victor D.

2017-01-01

A growing trend at universities is to use digital badges (micro-credentialing) for capturing the "soft skills" students gain outside of the classroom. Libraries can use this opportunity to become campus leaders in digital badges, using the system to not only promote their information literacy activities but to coordinate workshop…

Tutoring Online Tutors: Using Digital Badges to Encourage the Development of Online Tutoring Skills

ERIC Educational Resources Information Center

Hrastinski, Stefan; Cleveland-Innes, Martha; Stenbom, Stefan

2018-01-01

Online tutors play a critical role in e-learning and need to have an appropriate set of skills in addition to subject matter expertise. This paper explores how digital badges can be used to encourage the development of online tutoring skills. Based on previous research, we defined three digital badges, which are examples of essential tutoring…

Type testing the Model 6600 plus automatic TLD reader.

PubMed

Velbeck, K J; Luo, L Z; Streetz, K L

2006-01-01

The Harshaw Model 6600 Plus is a reader with a capacity for 200 TLD cards or 800 extremity cards. The new unit integrates more functionality, and significantly automates the QC and calibration process compared to the Model 6600. The Model 6600 Plus was tested against the IEC 61066 (1991-2012) procedures using Harshaw TLD-700H and TLD-600H, LiF:Mg,Cu,P based TLD Cards. An overview of the type testing procedures is presented. These include batch homogeneity, detection threshold, reproducibility, linearity, self-irradiation, residue, light effects on dosemeter, light leakage to reader, voltage and frequency, dropping and reader stability. The new TLD reader was found to meet all the IEC criteria by large margins and appears well suited for whole body, extremity and environmental dosimetry applications, with a high degree of dosimetric performance.

In vivo TLD dose measurements in catheter-based high-dose-rate brachytherapy.

PubMed

Adlienė, Diana; Jakštas, Karolis; Urbonavičius, Benas Gabrielis

2015-07-01

Routine in vivo dosimetry is well established in external beam radiotherapy; however, it is restricted mainly to detection of gross errors in high-dose-rate (HDR) brachytherapy due to complicated measurements in the field of steep dose gradients in the vicinity of radioactive source and high uncertainties. The results of in vivo dose measurements using TLD 100 mini rods and TLD 'pin worms' in catheter-based HDR brachytherapy are provided in this paper alongside with their comparison with corresponding dose values obtained using calculation algorithm of the treatment planning system. Possibility to perform independent verification of treatment delivery in HDR brachytherapy using TLDs is discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Deployment Health

DTIC Science & Technology

2006-08-11

thermo luminescent dosimeter ( TLD badge)) are required for performing specific tasks in a safe manner while deployed, personnel must be trained on the...monitoring devices (e.g., thermo luminescent dosimeter ( TLD badge)) as required by occupational specialty of personnel. (E4.A1.1.5.) 5.5.8 X X...assigned, attached, on temporary duty, or temporary additional duty to deployed units. Report the data electronically to the DMDC (at the SECRET level

Seismic Vibration Control of Elevated Water Tank by TLD and Validation of Full-Scale TLD Model through Real-Time-Hybrid-Testing

NASA Astrophysics Data System (ADS)

Roy, A.; Staino, A.; (D Ghosh, A.; Basu, B.; Chatterjee, S.

2016-09-01

Elevated water tanks (EWTs), being top-heavy structures, are highly vulnerable to earthquake forces, and several have experienced damage/failure in past seismic events. However, as these are critical facilities whose continued performance in the post-earthquake scenario is of vital concern, it is significant to investigate their seismic vibration control using reliable and cost-effective passive dampers such as the Tuned Liquid Damper (TLD). Here, this aspect is studied for flexible EWT structures, such as those with annular shaft supports. The criterion of tuning the sloshing frequency of the TLD to the structural frequency necessitates dimensions of the TLD larger than those hitherto examined in literature. Hence the nonlinear model of the TLD based on established shallow water wave theory is verified for large container size by employing Real-Time-Hybrid-Testing (RTHT). Simulation studies are further carried out on a realistic example of a flexible EWT structure with TLDs. Results indicate that the TLD can be applied very effectively for the seismic vibration mitigation of EWTs.

The psychosocial impact of NHS Digital Badges on a school-aged cohort.

PubMed

Alexander, Joanne H; Neill, Sarah

2018-01-01

Goal-oriented modalities of learning have long been used in educational settings to promote engagement and encourage a step-by-step approach to the acquisition of skills and knowledge. Historically, badges have been material, but in keeping with technological advancements there is a move towards encouraging greater digital engagement. Digital badges are today's version of the Scouts and Guides badge, a virtual non-material version, increasingly being utilized as a pedagogical resource in education and business settings. In 2015, National Health Service (NHS) England developed and launched its own digital badges aimed at supporting children and young people's education of health and well-being. This article presents findings from the first study to explore the psychosocial impact of NHS Digital Badges as perceived by primary school-aged children and their teachers. We conducted a small-scale evaluation involving children aged 8-10 ( n = 57) and their teachers ( n = 2), from a primary academy (school) in the north of England using NHS Digital Badges in their curriculum. Overwhelmingly, children and teachers reflected on the badges positively, as tools that have the capacity to build perseverance, develop emotional awareness, build relationships and enhance skill and knowledge acquisition. Some participants, though, raised vulnerability and safeguarding issues, and we explore the implications of these for future practice.

Individual Differences in Digital Badging: Do Learner Characteristics Matter?

ERIC Educational Resources Information Center

Fanfarelli, Joseph R.; McDaniel, Rudy

2015-01-01

Badge use has rapidly expanded in recent years and has benefited a variety of applications. However, a large portion of the research has applied a binary "useful" or "not useful" approach to badging. Few studies examine the characteristics of the user and the impact of those characteristics on the effectiveness of the badging…

Robust determination of effective atomic numbers for electron interactions with TLD-100 and TLD-100H thermoluminescent dosimeters

NASA Astrophysics Data System (ADS)

Taylor, M. L.

2011-04-01

Lithium fluoride thermoluminescent dosimeters (TLD) are the most commonly implemented for clinical dosimetry. The small physical magnitude of TLDs makes them attractive for applications such as small field measurement, in vivo dosimetry and measurement of out-of-field doses to critical structures. The most broadly used TLD is TLD-100 (LiF:Mg,Ti) and, for applications requiring higher sensitivity to low-doses, TLD-100H (LiF:Mg,Cu,P) is frequently employed. The radiological properties of these TLDs are therefore of significant interest. For the first time, in this study effective atomic numbers for radiative, collisional and total electron interaction processes are calculated for TLD-100 and TLD-100H dosimeters over the energy range 1 keV-100 MeV. This is undertaken using a robust, energy-dependent method of calculation rather than typical power-law approximations. The influence of dopant concentrations and unwanted impurities is also investigated. The two TLDs exhibit similar effective atomic numbers, ranging from approximately 5.77-6.51. Differences arising from the different dopants are most pronounced in low-energy radiative effects. The TLDs have atomic numbers approximately 1.48-2.06 times that of water. The effective atomic number of TLD-100H is consistently higher than that of TLD-100 over a broad energy range, due to the greater influence of the higher- Z dopants on the electron interaction cross sections. Typical variation in dopant concentration does not significantly influence the effective atomic number. The influence on TLD-100H is comparatively more pronounced than that on TLD-100. Contrariwise, unwanted hydroxide impurities influence TLD-100 more than TLD-100H. The effective atomic number is a key parameter that influences the radiological properties and energy response of TLDs. Although many properties of these TLDs have been studied rigorously, as yet there has been no investigation of their effective atomic numbers for electron interactions. The

Digital Badges and Library Instructional Programs: Academic Library Case Study

ERIC Educational Resources Information Center

Rodgers, Andrea Reed; Puterbaugh, Mark

2017-01-01

This case study describes the planning, implementation, and migration process of Eastern University Library's information literacy digital badge. Prior to implementing a badging program, information literacy sessions were informally embedded in first-year college writing courses as a "one-shot" presentation. Spurred on by accreditation…

Digital Badges: Recognizing, Assessing, and Motivating Learners in and out of School Contexts

ERIC Educational Resources Information Center

Ian O'Byrne, W.; Schenke, Katerina; Willis, James E., III.; Hickey, Daniel T.

2015-01-01

Digital badges are web-enabled tokens of accomplishment that contain specific claims and evidence about learning and achievement along with detailed evidence supporting those claims. Badges traditionally consist of an image and relevant metadata (e.g., badge name, description, criteria, issuer, evidence, date issued, standards, and tags). This…

Rethinking Workplace Learning in the Digital World: A Case Study of Open Badges

ERIC Educational Resources Information Center

Eaglen Bertrando, Sharen Linn

2017-01-01

The purpose of this collective case study was to explore digital badging in educational institutions as support for K-12 practitioners struggling to integrate technology into pedagogical practices. The researcher conducted a mixed-method study that captured perceptions about digital badges and follow-up interviews with selected badge users to…

Gamification of Nursing Education With Digital Badges.

PubMed

White, Meagan; Shellenbarger, Teresa

Digital badges (DBs) serve as an innovative approach to gamifying nursing education by engaging socially connected, technologically savvy nursing students in learning. Because assessment and credentialing mechanisms are housed and managed online, DBs are designed as visible indicators of accomplishment and skill. This article describes important considerations for faculty when incorporating game-based pedagogies such as DB into nursing education and identifies potential pitfalls with DB use that faculty should consider.

Employer Perceptions of Critical Information Literacy Skills and Digital Badges

ERIC Educational Resources Information Center

Raish, Victoria; Rimland, Emily

2016-01-01

Digital badges are an educational innovation used to measure learning of specific skills, such as information literacy. However, few studies have quantitatively surveyed employers for their perceptions about information literacy skills or digital badges. An online survey was developed and sent to employers to gauge perceptions of information…

Using Digital Badges for Developing High School Chemistry Laboratory Skills

ERIC Educational Resources Information Center

Hennah, Naomi; Seery, Michael K.

2017-01-01

Digital badges are emerging as an approach to offer microaccreditation for student achievements obtained in ongoing course work. They act to offer a formal recognition and framework for multiple small components which together make a significant contribution to student learning. Badges are promoted as a way of highlighting these particular…

Effects of the Badge Mechanism on Self-Efficacy and Learning Performance in a Game-Based English Learning Environment

ERIC Educational Resources Information Center

Yang, Jie Chi; Quadir, Benazir; Chen, Nian-Shing

2016-01-01

A growing number of studies have been conducted on digital game-based learning (DGBL). However, there has been a lack of attention paid to individuals' self-efficacy and learning performance in the implementation of DGBL. This study therefore investigated how the badge mechanism in DGBL enhanced users' self-efficacy in the subject domain of…

Badges to Acknowledge Open Practices: A Simple, Low-Cost, Effective Method for Increasing Transparency

PubMed Central

Kidwell, Mallory C.; Lazarević, Ljiljana B.; Baranski, Erica; Piechowski, Sarah; Falkenberg, Lina-Sophia; Sonnleitner, Carina; Fiedler, Susann; Nosek, Brian A.

2016-01-01

Beginning January 2014, Psychological Science gave authors the opportunity to signal open data and materials if they qualified for badges that accompanied published articles. Before badges, less than 3% of Psychological Science articles reported open data. After badges, 23% reported open data, with an accelerating trend; 39% reported open data in the first half of 2015, an increase of more than an order of magnitude from baseline. There was no change over time in the low rates of data sharing among comparison journals. Moreover, reporting openness does not guarantee openness. When badges were earned, reportedly available data were more likely to be actually available, correct, usable, and complete than when badges were not earned. Open materials also increased to a weaker degree, and there was more variability among comparison journals. Badges are simple, effective signals to promote open practices and improve preservation of data and materials by using independent repositories. PMID:27171007

TLD linearity vs. beam energy and modality.

PubMed

Troncalli, Andrew J; Chapman, Jane

2002-01-01

Thermoluminescent dosimetry (TLD) is considered to be a valuable dosimetric tool in determining patient dose. Lithium fluoride doped with magnesium and titanium (TLD-100) is widely used, as it does not display widely divergent energy dependence. For many years, we have known that TLD-100 shows supralinearity to dose. In a radiotherapy clinic, there are multiple energies and modality beams. This work investigates whether individual linearity corrections must be used for each beam or whether a single correction can be applied to all beams. The response of TLD as a function of dose was measured from 25 cGy to 1000 cGy on both electrons and photons from 6 to 18 MeV. This work shows that, within our measurement uncertainty, TLD-100 exhibits supralinearity at all megavoltage energies and modalities.

Performance of Harshaw TLD-100H two-element Dosemeter.

PubMed

Luo, L Z; Rotunda, J E

2006-01-01

One of the advantages of LiF based thermoluminescent (TL) materials is its tissue-equivalent property. The Harshaw TLD-100H (LiF:Mg,Cu,P) material has demonstrated that it has a near-flat photon energy response and high sensitivity. With the optimized dosemeter filters built into the holder, the Harshaw TLD-100H two-element dosemeter can be used as a whole body personnel dosemeter for gamma, X ray and beta monitoring without the use of an algorithm or correction factor. This paper presents the dose performance of the Harshaw TLD-100H two-element dosemeter against the ANSI N13.11-2001 standard and the results of tests that are required in IEC 1066 International Standard.

Teachers' Perceptions of Digital Badges as Recognition of Professional Development

ERIC Educational Resources Information Center

Jones, W. Monty; Hope, Samantha; Adams, Brianne

2018-01-01

This mixed methods study examined teachers' perceptions and uses of digital badges received as recognition of participation in a professional development program. Quantitative and qualitative survey data was collected from 99 K-12 teachers who were awarded digital badges in Spring 2016. In addition, qualitative data was collected through…

Dosimetry of high-energy electron linac produced photoneutrons and the bremsstrahlung gamma-rays using TLD-500 and TLD-700 dosimeter pairs

NASA Astrophysics Data System (ADS)

Mukherjee, Bhaskar; Makowski, Dariusz; Simrock, Stefan

2005-06-01

The neutron and gamma doses are crucial to interpreting the radiation effects in microelectronic devices operating in a high-energy accelerator environment. This report highlights a method for an accurate estimation of photoneutron and the accompanying bremsstrahlung (gamma) doses produced by a 450 MeV electron linear accelerator (linac) operating in pulsed mode. The principle is based on the analysis of thermoluminescence glow-curves of TLD-500 (Aluminium Oxide) and TLD-700 (Lithium Fluoride) dosimeter pairs. The gamma and fast neutron response of the TLD-500 and TLD-700 dosimeter pairs were calibrated with a 60Co (gamma) and a 241Am-Be (α, n) neutron standard-source, respectively. The Kinetic Energy Released in Materials (kerma) conversion factor for photoneutrons was evaluated by folding the neutron kerma (dose) distribution in 7LiF (the main component of the TLD-700 dosimeter) with the energy spectra of the 241Am-Be (α, n) neutrons and electron accelerator produced photoneutrons. The neutron kerma conversion factors for 241Am-Be neutrons and photoneutrons were calculated to be 2.52×10 -3 and 1.37×10 -3 μGy/a.u. respectively. The bremsstrahlung (gamma) dose conversion factor was evaluated to be 7.32×10 -4 μGy/a.u. The above method has been successfully utilised to assess the photoneutron and bremsstrahlung doses from a 450 MeV electron linac operating at DESY Research Centre in Hamburg, Germany.

Development and Evolution of Agriculturally Related Merit Badges Offered by the Boy Scouts of America

ERIC Educational Resources Information Center

Terry, Robert, Jr.

2013-01-01

Badges of Merit have been a primary component of Scouting programs since the inception of the movement more than 100 years ago. The diverse range of subjects for merit badges has included 32 programs relating directly to agriculture. The focus of this historical research was to identify when agriculturally related merit badges were introduced,…

Exploring Digital Badges in University Courses: Relationships between Quantity, Engagement, and Performance

ERIC Educational Resources Information Center

Fanfarelli, Joseph R.; McDaniel, Rudy

2017-01-01

Digital badging research is gaining momentum as instructors and administrators consider new models for assessing learning in nontraditional contexts (e.g., informal science learning programs, flexible online courses, adaptive learning systems). While many studies are examining the effectiveness of digital badges for pedagogical functions, such as…

Image-guided method for TLD-based in vivo rectal dose verification with endorectal balloon in proton therapy for prostate cancer

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

Hsi, Wen C.; Fagundes, Marcio; Zeidan, Omar

Purpose: To present a practical image-guided method to position an endorectal balloon that improves in vivo thermoluminiscent dosimeter (TLD) measurements of rectal doses in proton therapy for prostate cancer. Methods: TLDs were combined with endorectal balloons to measure dose at the anterior rectal wall during daily proton treatment delivery. Radiopaque metallic markers were employed as surrogates for balloon position reproducibility in rotation and translation. The markers were utilized to guide the balloon orientation during daily treatment employing orthogonal x-ray image-guided patient positioning. TLDs were placed at the 12 o'clock position on the anterior balloon surface at the midprostatic plane. Markersmore » were placed at the 3 and 9 o'clock positions on the balloon to align it with respect to the planned orientation. The balloon rotation along its stem axis, referred to as roll, causes TLD displacement along the anterior-posterior direction. The magnitude of TLD displacement is revealed by the separation distance between markers at opposite sides of the balloon on sagittal x-ray images. Results: A total of 81 in vivo TLD measurements were performed on six patients. Eighty-three percent of all measurements (65 TLD readings) were within +5% and -10% of the planning dose with a mean of -2.1% and a standard deviation of 3.5%. Examination of marker positions with in-room x-ray images of measured doses between -10% and -20% of the planned dose revealed a strong correlation between balloon roll and TLD displacement posteriorly from the planned position. The magnitude of the roll was confirmed by separations of 10-20 mm between the markers which could be corrected by manually adjusting the balloon position and verified by a repeat x-ray image prior to proton delivery. This approach could properly correct the balloon roll, resulting in TLD positioning within 2 mm along the anterior-posterior direction. Conclusions: Our results show that image-guided TLD-based

Image-guided method for TLD-based in vivo rectal dose verification with endorectal balloon in proton therapy for prostate cancer.

PubMed

Hsi, Wen C; Fagundes, Marcio; Zeidan, Omar; Hug, Eugen; Schreuder, Niek

2013-05-01

To present a practical image-guided method to position an endorectal balloon that improves in vivo thermoluminiscent dosimeter (TLD) measurements of rectal doses in proton therapy for prostate cancer. TLDs were combined with endorectal balloons to measure dose at the anterior rectal wall during daily proton treatment delivery. Radiopaque metallic markers were employed as surrogates for balloon position reproducibility in rotation and translation. The markers were utilized to guide the balloon orientation during daily treatment employing orthogonal x-ray image-guided patient positioning. TLDs were placed at the 12 o'clock position on the anterior balloon surface at the midprostatic plane. Markers were placed at the 3 and 9 o'clock positions on the balloon to align it with respect to the planned orientation. The balloon rotation along its stem axis, referred to as roll, causes TLD displacement along the anterior-posterior direction. The magnitude of TLD displacement is revealed by the separation distance between markers at opposite sides of the balloon on sagittal x-ray images. A total of 81 in vivo TLD measurements were performed on six patients. Eighty-three percent of all measurements (65 TLD readings) were within +5% and -10% of the planning dose with a mean of -2.1% and a standard deviation of 3.5%. Examination of marker positions with in-room x-ray images of measured doses between -10% and -20% of the planned dose revealed a strong correlation between balloon roll and TLD displacement posteriorly from the planned position. The magnitude of the roll was confirmed by separations of 10-20 mm between the markers which could be corrected by manually adjusting the balloon position and verified by a repeat x-ray image prior to proton delivery. This approach could properly correct the balloon roll, resulting in TLD positioning within 2 mm along the anterior-posterior direction. Our results show that image-guided TLD-based in vivo dosimetry for rectal dose verification

Evaluation of Exposure From a Low Energy X-Ray Device Using Thermoluminescent Dosimeters

NASA Technical Reports Server (NTRS)

Edwards, David L.; Harris, William S., Jr.

1997-01-01

The exposure from an electron beam welding device was evaluated using thermoluminescent dosimeters (TLDs). The device generated low energy X-rays which the current dose equivalent conversion algorithm was not designed to evaluate making it necessary to obtain additional information relating to TLD operation at the photon energies encountered with the device. This was accomplished by performing irradiations at the National Institute of Standards and Technology (NIST) using low energy X-ray techniques. The resulting data was used to determine TLD badge response for low energy X-rays and to establish the relationship between TLD element response and the dose equivalent at specific depths in tissue for these photon energies. The new energy/dose equivalent calibration data was used to calculate the shallow and eye dose equivalent of badges exposed to the device.

Girl Scout Camps and Badges: Engaging Girls in NASA Science

NASA Astrophysics Data System (ADS)

Harman, P. K.; DeVore, E. K.

2017-12-01

Reaching for the Stars: NASA Science for Girl Scouts (Girl Scout Stars) disseminates NASA STEM education-related resources, fosters interaction between Girl Scouts and NASA Subject Matter Experts (SMEs), and engages Girl Scouts in NASA science and programs through space science badges and summer camps. A space science badge is in development for each of the six levels of Girl Scouts: Daisies, Grades K - 1; Brownies, Grades 2 -3; Juniors, Grades 4 -5; Cadettes, Grades 6 -8; Seniors, Grades 9 -10: and Ambassadors, Grades 11 -12. Daisy badge will be accomplished by following three steps with two choices each. Brownie to Ambassador badges will be awarded by completing five steps with three choices for each. The badges are interwoven with science activities, role models (SMEs), and steps that lead girls to explore NASA missions. External evaluators monitor three rounds of field-testing and deliver formative assessment reports. Badges will be released in Fall of 2018 and 2019. Girl Scout Stars supports two unique camp experiences. The University of Arizona holds an Astronomy Destination, a travel and immersion adventure for individual girls ages 13 and older, which offers dark skies and science exploration using telescopes, and interacting with SMEs. Girls lean about motion of celestial objects and become astronomers. Councils send teams of two girls, a council representative and an amateur astronomer to Astronomy Camp at Goddard Space Flight Center. The teams were immersed in science content and activities, and a star party; and began to plan their new Girl Scout Astronomy Clubs. The girls will lead the clubs, aided by the council and amateur astronomer. Camps are evaluated by the Girl Scouts Research Institute. In Girl Scouting, girls discover their skills, talents and what they care about; connect with other Girl Scouts and people in their community; and take action to change the world. This is called the Girl Scout Leadership Experience. With girl-led, hands on

The Use of a Digital Badge as an Indicator and a Motivator

ERIC Educational Resources Information Center

Iwata, Jun; Telloyan, John; Murphy, Lynne; Wang, Shudong; Clayton, John

2017-01-01

Digital portfolios can provide a space where evidence of a learner's competency is stored and digital badges can be used in their portfolios as valid indicators of accomplishment, skill, knowledge, or interest. The authors issued "digital badges" to our students who successfully completed the modules of a Medical English Terminology…

Type Testing of Model 7200 Automatic TLD Reader.

PubMed

Malek Mohammadi, M; Hosseini Pooya, S M

2017-04-20

The type testing of measuring devices is one of the most important parts of a quality management system in a personal dosimetry services program. In this study, based upon the International Electrotechnical Commission (IEC) 62387 criteria, a reader-testing program was performed for a home-made personal thermoluminescent dosimetry (TLD) reader. The stability of the reader, the effects of light exposure, temperature and fluctuations of primary power supply on TLD read-outs as the main parameters were investigated in this program. Moreover, this study assesses some important criteria of dosimetry system including the non-linearity of response, reusability, after effect and overload that may include significant contribution in the performance of a reader. The results showed that the TLD reader met all requirements of the IEC for the reader tests by a large margin. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Microprocessor controlled portable TLD system

NASA Technical Reports Server (NTRS)

Apathy, I.; Deme, S.; Feher, I.

1996-01-01

An up-to-date microprocessor controlled thermoluminescence dosemeter (TLD) system for environmental and space dose measurements has been developed. The earlier version of the portable TLD system, Pille, was successfully used on Soviet orbital stations as well as on the US Space Shuttle, and for environmental monitoring. The new portable TLD system, Pille'95, consists of a reader and TL bulb dosemeters, and each dosemeter is provided with an EEPROM chip for automatic identification. The glow curve data are digitised and analysed by the program of the reader. The measured data and the identification number appear on the LED display of the reader. Up to several thousand measured data together with the glow curves can be stored on a removable flash memory card. The whole system is supplied either from built-in rechargeable batteries or from the mains of the space station.

Creating an Information Literacy Badges Program in Blackboard: A Formative Program Evaluation

ERIC Educational Resources Information Center

Tunon, Johanna; Ramirez, Laura Lucio; Ryckman, Brian; Campbell, Loy; Mlinar, Courtney

2015-01-01

A formative program evaluation using Stufflebeam's (2010) Context, Input, Process, Product (CIPP) model was conducted to assess the use of digital badges for tracking basic library instructional skills across academic programs at Nova Southeastern University. Based on the evaluation of pilot library modules and Blackboard Learn's badges…

Recognising Informal Elearning with Digital Badging: Evidence for a Sustainable Business Model

ERIC Educational Resources Information Center

Law, Patrina

2015-01-01

Digital badging as a trend in education is now recognised. It offers a way to reward and motivate, providing evidence of skills and achievements. Badged Open Courses (BOCs) were piloted by The Open University (OU) in 2013. The project built on research into the motivations and profiles of learners using free educational resources which the OU…

Developing Open Badges: A Comprehensive Approach

ERIC Educational Resources Information Center

Devedžic, Vladan; Jovanovic, Jelena

2015-01-01

Open Badges (OBs) have evolved as novel means of recognizing and credentialing skills/competences (either hard or soft skills) acquired in various learning settings (formal or informal, online or traditional classroom). In addition, they offer new ways of motivating learners and scaffolding the learning process, while also promoting values such as…

OSLD energy response performance and dose accuracy at 24 - 1250 keV: Comparison with TLD-100H and TLD-100

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

Kadir, A. B. A.; Priharti, W.; Samat, S. B.

OSLD was evaluated in terms of energy response and accuracy of the measured dose in comparison with TLD-100H and TLD-100. The OSLD showed a better energy response performance for H{sub p}(10) whereas for H{sub p}(0.07), TLD-100H is superior than the others. The OSLD dose accuracy is comparable with the other two dosimeters since it fulfilled the requirement of the ICRP trumpet graph analysis.

The dose-response of Harshaw TLD-700H.

PubMed

Velbeck, K J; Luo, L Z; Ramlo, M J; Rotunda, J E

2006-01-01

Harshaw TLD-700H (7LiF:Mg,Cu,P) was previously characterised for low- to high-dose ranges from 1 microGy to 20 Gy. This paper describes the studies and results of dose-response and linearity at much higher doses. TLD-700H is a near perfect dosimetric material with near tissue equivalence, flat energy response, and the ability to measure beta, gamma and X rays. These new results extend the applicability of Harshaw TLD-700H into more dosimetric measurement environments. The simple glow curve structure provides insignificant fade, eliminating special oven preparation methods experienced by other materials. The work presented in this paper quantifies the performance of Harshaw TLD-700H in extended ranges.

Badges: A Common Currency for Learning

ERIC Educational Resources Information Center

Bowen, Kyle; Thomas, Andrea

2014-01-01

Digital Badges--icons that can represent skills and achievements at a more fine-grained level than a degree--give colleges and universities a new way to document learning outcomes and to map the pathways students follow to earn a degree. They also provide a common currency to denote learning outcomes and give employers a visual representation and…

Preliminary Studies of Thermoluminescence Dosimeter (TLD) CaSO4:Dy Synthesis

NASA Astrophysics Data System (ADS)

Nuraeni, N.; Iskandar, F.; Waris, A.; Haryanto, F.

2017-07-01

Thermoluminescence dosimeter (TLD) CaSO4:Dy was synthesised by coprecipitation. The TLD was observed after radiation exposure to Strontium-90. The thermoluminescence intensity was read using a TLD Reader Harshaw 3500. The thermoluminescent response obtained was 59.29 nC. Then re-annealing was conducted with the temperature varied at 700, 800 and 900 °C. The thermoluminescent intensity obtained at temperatures of 700 °C, 800 °C and 900 °C was 66.12 nC, 169.45 nC, and 552.37 nC respectively. The sensitivity of the TLD increased in response to the re-annealing temperature rise. In addition to observing the thermoluminescence properties, a comparison was made between the TLD obtained from this experiment with an existing TLD in the market. Finally, also the glow-curve characteristics of the TLD were observed.

A LiF and BeO TLD based microdosimeter for space radiation risk assessment of astronauts

NASA Astrophysics Data System (ADS)

Mukherjee, B.

2018-06-01

The ratio of thermoluminescence glow curve area of BeO and LiF dosimeters was found to be proportional to average LET and quality factor (Q) of impinging mixed radiations. Using this phenomenon and widely available Thermoluminescence Dosimeter TLD-700 (7LiF: Mg,Ti) and BeO (Thermolux 995) chips a TLD-Microdosimeter (LiBe-14) emulating a much larger gas-filled Tissue Equivalent Proportional Counter (TEPC) was developed. The TEPC is an essential device of space radiation dosimetry widely used by international space agencies. The LiBe-14 is capable of assessing the LETTissue (5–300 keV/μm), quality factor Q (1–30) and associated dose equivalent H (0.1–1000 mSv) of any mixed radiation fields of interest, including space radiations predominant in Low Earth Orbit (LEO) environment. The TLD microdosimeter was calibrated using the secondary radiation fields produced by bombarding a 25 cm × 25 cm × 35 cm polystyrene phantom with 81, 119, 150, 177, 201 and 231 MeV protons from a Proton Therapy Medical Cyclotron. The TLD pair (BeO/LiF) was attached to the TEPC and placed lateral to the proton beam. The characteristics of space radiation inside the spacecraft are complex. Hence, personal dosimetry of astronauts in the space habitat is performed using "multi-element" dosimeters made of different types of TLD and CR-39 plastic nuclear track detector (PNTD). The TLD and PNTD are used to assess the sparsely (low LET) and densely (high LET) ionising radiation component respectively. This report elucidates the feasibility of LiBe-14 microdosimeter for the estimation of overall dose equivalent and "risk of exposure induced death" (REID) of astronauts working in LEO space stations.

The use of LiF (TLD-100) as an out-of-field dosimeter.

PubMed

Kry, Stephen F; Price, Michael; Followill, David; Mourtada, Firas; Salehpour, Mohammad

2007-09-24

The commonly used thermoluminescent dosimeter TLD-100 (Harshaw Chemical Company, Solon, OH) responds not only to photons and electrons, but also to neutrons that are produced during high-energy therapies. As a result, TLD-100 measurements outside of the treatment field are suspect when high-energy radiation is used. Although alternatives such as TLD-700 do not respond to neutrons, specialty dosimeters of this kind are expensive and are not routinely used in most clinics. In the current study, we examined the accuracy of TLD-100 in measuring the out-of-field photon dose as a function of treatment energy. To determine the accuracy of TLD-100 as compared with TLD-700, TLD-100 was irradiated outside of the treatment field by medical accelerators operated at 6, 10, 15, and 18 MV. In an effort to eliminate the response of TLD-100 to neutrons, TLD capsules were encased in varying thicknesses of cadmium foil (0.25 - 0.75 mm) before being irradiated at 18 MV. The out-of-field TLD-100 was found to be accurate at 6 MV and 10 MV, but to be substantially over-responsive at 15 MV and 18 MV (by up to 1063% relative to TLD-700). By wrapping the TLD-100 in up to 0.75 mm of cadmium, it was possible to drastically reduce (down to 39% on average) the over-response of the TLD-100; however, total removal of the over-responsiveness was not possible. Although TLD-100 is well suited for measuring out-of-field dose at energies as high as 10 MV, at higher energies (15 MV or greater), this dosimeter over-responds substantially and should not be used. Although encasing the TLD in cadmium minimized over-response to a degree, the reduction was not sufficient to make TLD-100 viable for measuring out-of-field dose at high treatment energies.

New Pathways to Credentialing: The Digital Badge

ERIC Educational Resources Information Center

DiSalvio, Philip

2016-01-01

With an increasing number of higher education institutions now offering "digital badges," some suggest that this credential has become a practical commodity in the world of college credentials. Colleges and universities are in a unique position to be the gatekeepers of many of those credentials. Among the many institutions of higher…

Thermoluminescence Dosimetry (TLD) and its Application in Medical Physics

NASA Astrophysics Data System (ADS)

Azorín Nieto, Juan

2004-09-01

Radiation dosimetry is fundamental in Medical Physics, involving patients and phantom dosimetry. In both cases thermoluminescence dosimetry (TLD) is the most appropriate technique for measuring the absorbed dose. In this paper thermoluminescence phenomenon as well as the use of TLD in radiodiagnosis and radiotherapy for in vivo or in phantom measurements is discussed. Some results of measurements made in radiotherapy and radiodiagnosis using home made LiF:Mg,Cu,P+PTFE TLD are presented.

Depth dose and off-axis characteristics of TLD in therapeutic pion beams.

PubMed

Hogstrom, K R; Irifune, T

1980-07-01

The thermoluminescent (TL) response of LiF (TLD-100, TLD-600, TLD-700) and Li2B4O7 (TLD-800) has been measured as a function of depth and off-axis position in a therapeutic negative-pion beam in order to evaluate their usefulness in pion radiotherapy. TLD-100, TLD-600, and TLD-800 have been shown to be of little use as in vivo dosemeters because the neutron kerma relative to that in tissue changes grossly with depth. The neutron source comes primarily from pion absorption in the lead-alloy collimator. The 200 degrees C TLD-700 response agrees well with the depth dose spectra, except for small changes due to the varying linear energy transfer (LET) distributions. This variation can be partially accounted for by incorporating the known LET response of LiF. The 260 degrees C peak of TLD-700 has been found to be approximately four times more sensitive than the 200 degrees C peak to high LET dose. Using a simple model of the LET responses, the measured 200 degrees C and 260 degrees C peaks predict total dose within +/- 4% and high LET dose within +/- 50%, therefore indicating TLD-700 to be a good in vivo dosemeter for total dose but only an indicator of high LET dose.

TAMPERPROOF FILM BADGE

DOEpatents

Kocher, L.F.

1958-10-01

A persornel dosimeter film badge made of plastic, with provision for a picture of the wearer and an internal slide containing photographic film that is sensitive to various radiations, is described. Four windows made of differing material selectively attenuate alpha, beta, gamma rays, and neutrons so as to distinguish the particular type of radiation the wearer was subjected to. In addition, a lead shield has the identification number of the wearer perforated thereon so as to identify the film after processing. An internal magnetically actuated latch securely locks the slide within the body, and may be withdrawn only upon the external application of two strong magnetic forces in order to insure that the wearer or other curious persons will not accidentally expose the film to visual light.

Measurement of dose given by Co-60 in radiotherapy with TLD-500

NASA Astrophysics Data System (ADS)

Tanır, Güneş; Cengiz, Ferhat; Hicabi Bölükdemir, M.

2012-04-01

The uses of dosimeters based on optically stimulated luminescence technique have become widespread in clinical applications. In the present study, the dose values given by Cobalt-60 radiotherapy machine were measured with optically stimulated luminescence (OSL) technique using TLD-500 and compared with those of commonly used ionization chamber dosimeter system. The percentage depth dose (DD%) values and graphs were formed. OSL system with TLD-500 can be reliably used as medical and personal dosimeter.

Nonlinear multimodal model for TLD of irregular tank geometry and small fluid depth

NASA Astrophysics Data System (ADS)

Love, J. S.; Tait, M. J.

2013-11-01

Tuned liquid dampers (TLDs) utilize sloshing fluid to absorb and dissipate structural vibrational energy. TLDs of irregular or complex tank geometry may be required in practice to avoid tank interference with fixed structural or mechanical components. The literature offers few analytical models to predict the response of this type of TLD, particularly when the fluid depth is small. In this paper, a multimodal model is developed utilizing a Boussinesq-type modal theory which is valid for small TLD fluid depths. The Bateman-Luke variational principle is employed to develop a system of coupled nonlinear ordinary differential equations which describe the fluid response when the tank is subjected to base excitation. Energy dissipation is incorporated into the model from the inclusion of damping screens. The fluid model is used to describe the response of a 2D structure-TLD system when the structure is subjected to external loading and the TLD tank geometry is irregular.

TLD and OSLD dosimetry systems for remote audits of radiotherapy external beam calibration.

PubMed

Alvarez, P; Kry, S F; Stingo, F; Followill, D

2017-11-01

The Imaging and Radiation Oncology Core QA Center in Houston (IROC-H) performs remote dosimetry audits of more than 20,000 megavoltage photon and electron beams each year. Both a thermoluminescent dosimeter (TLD-100) and optically stimulated luminescent dosimeter (OSLD; nanoDot) system are commissioned for this task, with the OSLD system being predominant due to the more time-efficient read-out process. The measurement apparatus includes 3 TLD or 2 OSLD in an acrylic mini-phantom, which are irradiated by the institution under reference geometry. Dosimetry systems are calibrated based on the signal-to-dose conversion established with reference dosimeters irradiated in a Co-60 beam, using a reference dose of 300 cGy for TLD and 100 cGy for OSLD. The uncertainty in the dose determination is 1.3% for TLD and 1.6% for OSLD at the one sigma level. This accuracy allows for a tolerance of ±5% to be used.

Design Principles for Digital Badges Used in Libraries

ERIC Educational Resources Information Center

Rimland, Emily; Raish, Victoria

2017-01-01

Digital badges give libraries greater flexibility in delivering impactful instruction to students. They serve as flexible, stackable microcredentials that sequence an information literacy experience across the curriculum. Design considerations rooted in learning theory have a foundation through which to drive decisions. Information literacy badges…

Digital Badge Systems: The Promise and Potential

ERIC Educational Resources Information Center

Thigpen, Kamila

2014-01-01

Digital badges--defined as digital credentials that convey an array of skills, interests, and achievements--are steadily growing in acceptance as a way to validate learning that takes place not only in school but also at home and in a number of other out-of-school settings. This report builds on the growing body of literature about digital badge…

The Origins of Specificity in the Microcin-Processing Protease TldD/E.

PubMed

Ghilarov, Dmitry; Serebryakova, Marina; Stevenson, Clare E M; Hearnshaw, Stephen J; Volkov, Dmitry S; Maxwell, Anthony; Lawson, David M; Severinov, Konstantin

2017-10-03

TldD and TldE proteins are involved in the biosynthesis of microcin B17 (MccB17), an Escherichia coli thiazole/oxazole-modified peptide toxin targeting DNA gyrase. Using a combination of biochemical and crystallographic methods we show that E. coli TldD and TldE interact to form a heterodimeric metalloprotease. TldD/E cleaves the N-terminal leader sequence from the modified MccB17 precursor peptide, to yield mature antibiotic, while it has no effect on the unmodified peptide. Both proteins are essential for the activity; however, only the TldD subunit forms a novel metal-containing active site within the hollow core of the heterodimer. Peptide substrates are bound in a sequence-independent manner through β sheet interactions with TldD and are likely cleaved via a thermolysin-type mechanism. We suggest that TldD/E acts as a "molecular pencil sharpener": unfolded polypeptides are fed through a narrow channel into the active site and processively truncated through the cleavage of short peptides from the N-terminal end. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Four passive sampling elements (quatrefoil)--II. Film badges for monitoring radon and its progeny.

PubMed

Tommasino, L; Tokonami, S

2011-05-01

The four passive samplers (quatrefoil) already described in a parallel paper, make it possible to obtain thin radiation sources, useful for alpha and beta counting by any passive and real-time detector. In the present paper, the applications of this quatrefoil for measuring radon gas by etch-track detectors will be described. In the case of radon measurements, different solids have been identified, with radon-sorption partition coefficients related to air from 1 to 2000. Uniquely compact radon badges can be obtained by using a layer of these solids facing an alpha track-etch detector. These radon badges make it possible to overcome most of the shortcomings of existing passive monitors. Moreover, these badges show promise for studying the radon solubility of polymer films.

Thermoluminescent dosimeters (TLD) quality assurance network in the Czech Republic.

PubMed

Kroutilķková, Daniela; Novotný, Josef; Judas, Libor

2003-02-01

The Czech thermoluminescent dosimeters (TLD) quality assurance network was established in 1997. Its aim is to pursue a regular independent quality audit in Czech radiotherapy centres and to support state supervision. The audit is realised via mailed TL dosimetry. The TLD system consists of encapsulated LiF:Mg,Ti powder (type MT-N) read with Harshaw manual reader model 4000. Basic mode of the TLD audit covers measurements under reference conditions, specifically beam calibration checks for all clinically used photon and electron beams. Advanced mode consists of measurements under both reference and non-reference conditions using a solid multipurpose phantom ('Leuven phantom') for photon beams. The radiotherapy centres are instructed to deliver to the TLD on central beam axis absorbed dose of 2 Gy calculated with their treatment planning system for a particular treatment set-up. The TLD measured doses are compared with the calculated ones. Deviations of +/-3% are considered acceptable for both basic and advanced mode of the audit. There are 34 radiotherapy centres in the Czech Republic. They undergo the basic mode of the TLD audit regularly every 2 years. If a centre shows a deviation outside the acceptance level, it is audited more often. Presently, most of the checked beams comply with the acceptance level. The advanced TLD audit has been implemented as a pilot study for the present. The results were mostly within the acceptance limit for the measurements on-axis, whereas for off-axis points they fell beyond the limit more frequently, especially for set-ups with inhomogeneities, oblique incidence and wedges. The results prove the importance of the national TLD quality assurance network. It has contributed to the improvement of clinical dosimetry in the Czech Republic. In addition, it helps the regulatory authority to monitor effectively and regularly radiotherapy centres.

77 FR 11195 - Announcement of Competition Under the America COMPETES Reauthorization Act of 2011: Badges for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-24

....dmlcompetition.net/Competition/4/badges-projects.php?id=2667 . VA does not anticipate that it will issue badges... lean Six Sigma. Law Enforcement, which may include specialties such as criminal investigation and... alternative fuels. Information Technology, including all phases of software development and IT project...

Occurrence of phthalate diesters (phthalates), p-hydroxybenzoic acid esters (parabens), bisphenol A diglycidyl ether (BADGE) and their derivatives in indoor dust from Vietnam: Implications for exposure.

PubMed

Tran, Tri Manh; Minh, Tu Binh; Kumosani, Taha A; Kannan, Kurunthachalam

2016-02-01

Phthalate diesters (phthalates), esters of p-hydroxybenzoic acid (parabens), and bisphenol A diglycidyl ether (BADGE) are used in personal care products, food packages, household products, or pharmaceuticals. These compounds possess endocrine-disrupting potentials and have been reported to occur in the environment. Nevertheless, no previous studies have reported the occurrence of these compounds in indoor dust from Vietnam. In this study, nine phthalates, six parabens, and four BADGEs were determined in indoor dust samples collected from Hanoi, Hatinh, Hungyen, and Thaibinh, in Vietnam. Total concentrations of phthalates, parabens, and BADGEs in indoor dust ranged from 3440 to 106,000 ng/g (median: 22,600 ng/g), 40-840 ng/g (median: 123 ng/g), and 23 to 1750 ng/g (median: 184 ng/g), respectively. Based on the measured median concentration of phthalates, parabens, and BADGEs in indoor dust, we estimated human exposure doses to these compounds through indoor dust ingestion for various age groups. The exposure doses to phthalates, parabens, and BADGEs decreased with age and ranged from 19.4 to 90.4 ng/kg-bw/d, 0.113-0.528 ng/kg-bw/d, and 0.158-0.736 ng/kg-bw/d, respectively. This is the first study on the occurrence and human exposure of phthalates, parabens, and BADGEs in indoor dust from Vietnam. Copyright © 2015 Elsevier Ltd. All rights reserved.

SU-E-T-308: Systematic Characterization of the Energy Response of Different LiF TLD Crystals for Dosimetry Applications

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

Pena, E; Caprile, P; Sanchez-Nieto, B

Purpose: The thermoluminiscense dosimeters (TLDs) are widely used in personal and clinical dosimetry due to its small size, good sensitivity and tissue equivalence, among other advantages. This study presents the characterization of Lithium Fluoride based TLDs, in terms of their absorbed dose response to successive irradiation cycles in a broad range of beam energies, measured under reference conditions. Methods: Four types of Harshaw TLD chips were used: TLD-100, TLD-600 TLD-700 and 100-H. They were irradiated with 10 photon beams of different energy spectrums, from 28 kVp to 18MV (in 30 consecutive cycles for 6 and 18 MV). Results: It wasmore » found that the response of the dosimetric system was stabilized (less than ±3%) after 10 cycles for TLD-600 and TLD-700. In the case of TLD-100 and TLD-100H this dependence was not observed. A decreased response to increasing beam energy in terms of absorbed dose to water was observed, as expected, except for TLD-100H which showed the opposite behavior. The less energy dependent detector was the TLD-100H exhibiting a maximum deviation of 12%. The highest variation observed was 33% for TLD-100. The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy. Conclusion: The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy.« less

Oceanography. Boy Scouts of America Merit Badge Series.

ERIC Educational Resources Information Center

Boy Scouts of America, Irving, TX.

Presented are various activities and projects intended to help Boy Scouts earn a merit badge in oceanography. Each project and/or activity is related to a requirement (objective) found in a list at the beginning of the booklet. Topic areas and/or related activities and projects include: (1) nature of oceanography (naming oceanography branches,…

Common Badging and Access Control System (CBACS)

NASA Technical Reports Server (NTRS)

Baldridge, Tim

2005-01-01

The goals of the project are: Achieve high business value through a common badging and access control system that integrates with smart cards. Provide physical (versus logical) deployment of smart cards initially. Provides a common consistent and reliable environment into which to release the smart card. Gives opportunity to develop agency-wide consistent processes, practices and policies. Enables enterprise data capture and management. Promotes data validation prior to SC issuance.

9 CFR 306.3 - Badge as identification of inspectors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Badge as identification of inspectors. 306.3 Section 306.3 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY...

9 CFR 306.3 - Badge as identification of inspectors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Badge as identification of inspectors. 306.3 Section 306.3 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY...

Developmental toxicity of bisphenol A diglycidyl ether (epoxide resin badge) during the early life cycle of a native amphibian species.

PubMed

Hutler Wolkowicz, Ianina; Svartz, Gabriela V; Aronzon, Carolina M; Pérez Coll, Christina

2016-12-01

Bisphenol A diglycidyl ether (BADGE) is used in packaging materials, in epoxy adhesives, and as an additive for plastics, but it is also a potential industrial wastewater contaminant. The aim of the present study was to evaluate the adverse effects of BADGE on Rhinella arenarum by means of standardized bioassays at embryo-larval development. The results showed that BADGE was more toxic to embryos than to larvae at all exposure times. At acute exposure, lethality rates of embryos exposed to concentrations of 0.0005 mg/L BADGE and greater were significantly higher than rates in the vehicle control, whereas lethality rates of larvae were significantly higher in concentrations of 10 mg/L BADGE and greater. The toxicity then increased significantly, with 96-h median lethal concentrations (LC50s) of 0.13 mg/L and 6.9 mg/L BADGE for embryos and larvae, respectively. By the end of the chronic period, the 336-h LC50s were 0.04 mg/L and 2.2 mg/L BADGE for embryos and larvae, respectively. This differential sensitivity was also ascertained by the 24-h pulse exposure experiments, in which embryos showed a stage-dependent toxicity, with blastula being the most sensitive stage and S.23 the most resistant. The most important sublethal effects in embryos were cell dissociation and delayed development, whereas the main abnormalities observed in larvae related to neurotoxicity, as scare response to stimuli and narcotic effect. Environ Toxicol Chem 2016;35:3031-3038. © 2016 SETAC. © 2016 SETAC.

Positional glow curve simulation for thermoluminescent detector (TLD) system design

NASA Astrophysics Data System (ADS)

Branch, C. J.; Kearfott, K. J.

1999-02-01

Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and/or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design.

A methodology for TLD postal dosimetry audit of high-energy radiotherapy photon beams in non-reference conditions.

PubMed

Izewska, Joanna; Georg, Dietmar; Bera, Pranabes; Thwaites, David; Arib, Mehenna; Saravi, Margarita; Sergieva, Katia; Li, Kaibao; Yip, Fernando Garcia; Mahant, Ashok Kumar; Bulski, Wojciech

2007-07-01

A strategy for national TLD audit programmes has been developed by the International Atomic Energy Agency (IAEA). It involves progression through three sequential dosimetry audit steps. The first step audits are for the beam output in reference conditions for high-energy photon beams. The second step audits are for the dose in reference and non-reference conditions on the beam axis for photon and electron beams. The third step audits involve measurements of the dose in reference, and non-reference conditions off-axis for open and wedged symmetric and asymmetric fields for photon beams. Through a co-ordinated research project the IAEA developed the methodology to extend the scope of national TLD auditing activities to more complex audit measurements for regular fields. Based on the IAEA standard TLD holder for high-energy photon beams, a TLD holder was developed with horizontal arm to enable measurements 5cm off the central axis. Basic correction factors were determined for the holder in the energy range between Co-60 and 25MV photon beams. New procedures were developed for the TLD irradiation in hospitals. The off-axis measurement methodology for photon beams was tested in a multi-national pilot study. The statistical distribution of dosimetric parameters (off-axis ratios for open and wedge beam profiles, output factors, wedge transmission factors) checked in 146 measurements was 0.999+/-0.012. The methodology of TLD audits in non-reference conditions with a modified IAEA TLD holder has been shown to be feasible.

9 CFR 306.3 - Badge as identification of inspectors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Badge as identification of inspectors. 306.3 Section 306.3 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION ASSIGNMENT...

9 CFR 306.3 - Badge as identification of inspectors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Badge as identification of inspectors. 306.3 Section 306.3 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION ASSIGNMENT...

9 CFR 306.3 - Badge as identification of inspectors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Badge as identification of inspectors. 306.3 Section 306.3 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION ASSIGNMENT...

"Badges" Earned Online Pose Challenge to Traditional College Diplomas

ERIC Educational Resources Information Center

Young, Jeffrey R.

2012-01-01

The spread of a seemingly playful alternative to traditional diplomas, inspired by Boy Scout achievement patches and video-game power-ups, suggests that the standard certification system no longer works in today's fast-changing job market. Educational upstarts across the Web are adopting "badges" to certify skills and abilities. If scouting…

"Badges" Earned Online Pose Challenge to Traditional College Diplomas

ERIC Educational Resources Information Center

Young, Jeffrey R.

2012-01-01

The spread of a seemingly playful alternative to traditional diplomas, inspired by Boy Scout achievement patches and video-game power-ups, suggests that the standard certification system no longer works in today's fast-changing job market. Educational upstarts across the Web are adopting systems of "badges" to certify skills and abilities.…

X-ray surface dose measurements using TLD extrapolation.

PubMed

Kron, T; Elliot, A; Wong, T; Showell, G; Clubb, B; Metcalfe, P

1993-01-01

Surface dose measurements in therapeutic x-ray beams are of importance in determining the dose to the skin of patients undergoing radiotherapy. Measurements were performed in the 6-MV beam of a medical linear accelerator with LiF thermoluminescence dosimeters (TLD) using a solid water phantom. TLD chips (surface area 3.17 x 3.17 cm2) of three different thicknesses (0.230, 0.099, and 0.038 g/cm2) were used to extrapolate dose readings to an infinitesimally thin layer of LiF. This surface dose was measured for field sizes ranging from 1 x 1 cm2 to 40 x 40 cm2. The surface dose relative to maximum dose was found to be 10.0% for a field size of 5 x 5 cm2, 16.3% for 10 x 10 cm2, and 26.9% for 20 x 20 cm2. Using a 6-mm Perspex block tray in the beam increased the surface dose in these fields to 10.7%, 17.7%, and 34.2% respectively. Due to the small size of the TLD chips, TLD extrapolation is applicable also for intracavity and exit dose determinations. The technique used for in vivo dosimetry could provide clinicians information about the build up of dose up to 1-mm depth in addition to an extrapolated surface dose measurement.

Response of TLD-100 in mixed fields of photons and electrons.

PubMed

Lawless, Michael J; Junell, Stephanie; Hammer, Cliff; DeWerd, Larry A

2013-01-01

Thermoluminescent dosimeters (TLDs) are routinely used for dosimetric measurements of high energy photon and electron fields. However, TLD response in combined fields of photon and electron beam qualities has not been characterized. This work investigates the response of TLD-100 (LiF:Mg,Ti) to sequential irradiation by high-energy photon and electron beam qualities. TLDs were irradiated to a known dose by a linear accelerator with a 6 MV photon beam, a 6 MeV electron beam, and a NIST-traceable (60)Co beam. TLDs were also irradiated in a mixed field of the 6 MeV electron beam and the 6 MV photon beam. The average TLD response per unit dose of the TLDs for each linac beam quality was normalized to the average response per unit dose of the TLDs irradiated by the (60)Co beam. Irradiations were performed in water and in a Virtual Water™ phantom. The 6 MV photon beam and 6 MeV electron beam were used to create dose calibration curves relating TLD response to absorbed dose to water, which were applied to the TLDs irradiated in the mixed field. TLD relative response per unit dose in the mixed field was less sensitive than the relative response in the photon field and more sensitive than the relative response in the electron field. Application of the photon dose calibration curve to the TLDs irradiated in a mixed field resulted in an underestimation of the delivered dose, while application of the electron dose calibration curve resulted in an overestimation of the dose. The relative response of TLD-100 in mixed fields fell between the relative response in the photon-only and electron-only fields. TLD-100 dosimetry of mixed fields must account for this intermediate response to minimize the estimation errors associated with calibration factors obtained from a single beam quality.

Goal Setting and Open Digital Badges in Higher Education

ERIC Educational Resources Information Center

Cheng, Zui; Watson, Sunnie Lee; Newby, Timothy James

2018-01-01

While Open Digital Badges (ODBs) has gained an increasing recognition as micro-credentials, many researchers foresee the role of ODBs as an innovative learning tool to enhance learning experiences beyond that of an alternative credential. However, little research has explored this topic. The purposes of this paper are to 1) argue that one way to…

42 CFR 82.14 - What types of information could be used in dose reconstructions?

Code of Federal Regulations, 2011 CFR

2011-10-01

...) External dosimetry data, including external dosimeter readings (film badge, TLD, neutron dosimeters); and, (2) Pocket ionization chamber data. (c) Internal dosimetry data, including: (1) Urinalysis results; (2) Fecal sample results; (3) In Vivo measurement results; (4) Incident investigation reports; (5...

42 CFR 82.14 - What types of information could be used in dose reconstructions?

Code of Federal Regulations, 2012 CFR

2012-10-01

...) External dosimetry data, including external dosimeter readings (film badge, TLD, neutron dosimeters); and, (2) Pocket ionization chamber data. (c) Internal dosimetry data, including: (1) Urinalysis results; (2) Fecal sample results; (3) In Vivo measurement results; (4) Incident investigation reports; (5...

42 CFR 82.14 - What types of information could be used in dose reconstructions?

Code of Federal Regulations, 2010 CFR

2010-10-01

...) External dosimetry data, including external dosimeter readings (film badge, TLD, neutron dosimeters); and, (2) Pocket ionization chamber data. (c) Internal dosimetry data, including: (1) Urinalysis results; (2) Fecal sample results; (3) In Vivo measurement results; (4) Incident investigation reports; (5...

42 CFR 82.14 - What types of information could be used in dose reconstructions?

Code of Federal Regulations, 2014 CFR

2014-10-01

...) External dosimetry data, including external dosimeter readings (film badge, TLD, neutron dosimeters); and, (2) Pocket ionization chamber data. (c) Internal dosimetry data, including: (1) Urinalysis results; (2) Fecal sample results; (3) In Vivo measurement results; (4) Incident investigation reports; (5...

42 CFR 82.14 - What types of information could be used in dose reconstructions?

Code of Federal Regulations, 2013 CFR

2013-10-01

...) External dosimetry data, including external dosimeter readings (film badge, TLD, neutron dosimeters); and, (2) Pocket ionization chamber data. (c) Internal dosimetry data, including: (1) Urinalysis results; (2) Fecal sample results; (3) In Vivo measurement results; (4) Incident investigation reports; (5...

Investigation of LiF, Mg and Ti (TLD-100) Reproducibility.

PubMed

Sadeghi, M; Sina, S; Faghihi, R

2015-12-01

LiF, Mg and Ti cubical TLD chips (known as TLD-100) are widely used for dosimetry purposes. The repeatability of TL dosimetry is investigated by exposing them to doses of (81, 162 and 40.5 mGy) with 662keV photons of Cs-137. A group of 40 cubical TLD chips was randomly selected from a batch and the values of Element Correction Coefficient (ECC) were obtained 4 times by irradiating them to doses of 81 mGy (two times), 162mGy and 40.5mGy. Results of this study indicate that the average reproducibility of ECC calculation for 40 TLDs is 1.5%, while these values for all chips do not exceed 5%.

Exploring "Badging" for Peer Review, Extended Learning and Evaluation, and Reflective/Critical Feedback within an Online Graduate Course

ERIC Educational Resources Information Center

O'Connor, Eileen A.; McQuigge, Amy

2013-01-01

The use of digital badges for peer-credentialing web-shared work offers the promise of extending classroom learning beyond explicit course objectives and evaluations. This pilot study of peer-awarded badges examines the results of an online graduate course where students voted on and evaluated the web-shared work of their colleagues on different…

Symbolism and Psychological Realism in "The Red Badge of Courage."

ERIC Educational Resources Information Center

McDermott, John J.

1968-01-01

In "The Red Badge of Courage," Stephen Crane overcomes serious artistic difficulties to depict a complicated psychological change in his protagonist, Henry Fleming, an unsophisticated and inarticulate farm boy. To embody the development of this protagonist, Crane uses a series of thematically-related incidents and a set of thematic…

Open Badges: Novel Means to Motivate, Scaffold and Recognize Learning

ERIC Educational Resources Information Center

Jovanovic, Jelena; Devedzic, Vladan

2015-01-01

This report is centered on the emerging concept and technology of Open Badges (OBs) that are offering novel means and practices of motivating, scaffolding, recognizing, and credentialing learning. OBs are closely associated with values such as openness and learners' agency, participatory learning and peer-learning communities. This report points…

Neutron dose measurements of Varian and Elekta linacs by TLD600 and TLD700 dosimeters and comparison with MCNP calculations

PubMed Central

Nedaie, Hassan Ali; Darestani, Hoda; Banaee, Nooshin; Shagholi, Negin; Mohammadi, Kheirollah; Shahvar, Arjang; Bayat, Esmaeel

2014-01-01

High-energy linacs produce secondary particles such as neutrons (photoneutron production). The neutrons have the important role during treatment with high energy photons in terms of protection and dose escalation. In this work, neutron dose equivalents of 18 MV Varian and Elekta accelerators are measured by thermoluminescent dosimeter (TLD) 600 and TLD700 detectors and compared with the Monte Carlo calculations. For neutron and photon dose discrimination, first TLDs were calibrated separately by gamma and neutron doses. Gamma calibration was carried out in two procedures; by standard 60Co source and by 18 MV linac photon beam. For neutron calibration by 241Am-Be source, irradiations were performed in several different time intervals. The Varian and Elekta linac heads and the phantom were simulated by the MCNPX code (v. 2.5). Neutron dose equivalent was calculated in the central axis, on the phantom surface and depths of 1, 2, 3.3, 4, 5, and 6 cm. The maximum photoneutron dose equivalents which calculated by the MCNPX code were 7.06 and 2.37 mSv.Gy-1 for Varian and Elekta accelerators, respectively, in comparison with 50 and 44 mSv.Gy-1 achieved by TLDs. All the results showed more photoneutron production in Varian accelerator compared to Elekta. According to the results, it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry inside the linac field due to high photon flux, while MCNPX code is an appropriate alternative for studying photoneutron production. PMID:24600167

Neutron dose measurements of Varian and Elekta linacs by TLD600 and TLD700 dosimeters and comparison with MCNP calculations.

PubMed

Nedaie, Hassan Ali; Darestani, Hoda; Banaee, Nooshin; Shagholi, Negin; Mohammadi, Kheirollah; Shahvar, Arjang; Bayat, Esmaeel

2014-01-01

High-energy linacs produce secondary particles such as neutrons (photoneutron production). The neutrons have the important role during treatment with high energy photons in terms of protection and dose escalation. In this work, neutron dose equivalents of 18 MV Varian and Elekta accelerators are measured by thermoluminescent dosimeter (TLD) 600 and TLD700 detectors and compared with the Monte Carlo calculations. For neutron and photon dose discrimination, first TLDs were calibrated separately by gamma and neutron doses. Gamma calibration was carried out in two procedures; by standard 60Co source and by 18 MV linac photon beam. For neutron calibration by (241)Am-Be source, irradiations were performed in several different time intervals. The Varian and Elekta linac heads and the phantom were simulated by the MCNPX code (v. 2.5). Neutron dose equivalent was calculated in the central axis, on the phantom surface and depths of 1, 2, 3.3, 4, 5, and 6 cm. The maximum photoneutron dose equivalents which calculated by the MCNPX code were 7.06 and 2.37 mSv.Gy(-1) for Varian and Elekta accelerators, respectively, in comparison with 50 and 44 mSv.Gy(-1) achieved by TLDs. All the results showed more photoneutron production in Varian accelerator compared to Elekta. According to the results, it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry inside the linac field due to high photon flux, while MCNPX code is an appropriate alternative for studying photoneutron production.

Acoustical and Intelligibility Test of the Vocera(Copyright) B3000 Communication Badge

NASA Technical Reports Server (NTRS)

Archer, Ronald; Litaker, Harry; Chu, Shao-Sheng R.; Simon, Cory; Romero, Andy; Moses, Haifa

2012-01-01

To communicate with each other or ground support, crew members on board the International Space Station (ISS) currently use the Audio Terminal Units (ATU), which are located in each ISS module. However, to use the ATU, crew members must stop their current activity, travel to a panel, and speak into a wall-mounted microphone, or use either a handheld microphone or a Crew Communication Headset that is connected to a panel. These actions unnecessarily may increase task times, lower productivity, create cable management issues, and thus increase crew frustration. Therefore, the Habitability and Human Factors and Human Interface Branches at the NASA Johnson Space Center (JSC) are currently investigating a commercial-off-the-shelf (COTS) wireless communication system, Vocera(C), as a near-term solution for ISS communication. The objectives of the acoustics and intelligibility testing of this system were to answer the following questions: 1. How intelligibly can a human hear the transmitted message from a Vocera(c) badge in three different noise environments (Baseline = 20 dB, US Lab Module = 58 dB, Russian Module = 70.6 dB)? 2. How accurate is the Vocera(C) badge at recognizing voice commands in three different noise environments? 3. What body location (chest, upper arm, or shoulder) is optimal for speech intelligibility and voice recognition accuracy of the Vocera(C) badge on a human in three different noise environments?

Response of TLD-100 in mixed fields of photons and electrons

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

Lawless, Michael J.; Junell, Stephanie; Hammer, Cliff

Purpose: Thermoluminescent dosimeters (TLDs) are routinely used for dosimetric measurements of high energy photon and electron fields. However, TLD response in combined fields of photon and electron beam qualities has not been characterized. This work investigates the response of TLD-100 (LiF:Mg,Ti) to sequential irradiation by high-energy photon and electron beam qualities. Methods: TLDs were irradiated to a known dose by a linear accelerator with a 6 MV photon beam, a 6 MeV electron beam, and a NIST-traceable {sup 60}Co beam. TLDs were also irradiated in a mixed field of the 6 MeV electron beam and the 6 MV photon beam.more » The average TLD response per unit dose of the TLDs for each linac beam quality was normalized to the average response per unit dose of the TLDs irradiated by the {sup 60}Co beam. Irradiations were performed in water and in a Virtual Water Trade-Mark-Sign phantom. The 6 MV photon beam and 6 MeV electron beam were used to create dose calibration curves relating TLD response to absorbed dose to water, which were applied to the TLDs irradiated in the mixed field. Results: TLD relative response per unit dose in the mixed field was less sensitive than the relative response in the photon field and more sensitive than the relative response in the electron field. Application of the photon dose calibration curve to the TLDs irradiated in a mixed field resulted in an underestimation of the delivered dose, while application of the electron dose calibration curve resulted in an overestimation of the dose. Conclusions: The relative response of TLD-100 in mixed fields fell between the relative response in the photon-only and electron-only fields. TLD-100 dosimetry of mixed fields must account for this intermediate response to minimize the estimation errors associated with calibration factors obtained from a single beam quality.« less

Investigation of LiF, Mg and Ti (TLD-100) Reproducibility

PubMed Central

Sadeghi, M.; Sina, S.; Faghihi, R.

2015-01-01

LiF, Mg and Ti cubical TLD chips (known as TLD-100) are widely used for dosimetry purposes. The repeatability of TL dosimetry is investigated by exposing them to doses of (81, 162 and 40.5 mGy) with 662keV photons of Cs-137. A group of 40 cubical TLD chips was randomly selected from a batch and the values of Element Correction Coefficient (ECC) were obtained 4 times by irradiating them to doses of 81 mGy (two times), 162mGy and 40.5mGy. Results of this study indicate that the average reproducibility of ECC calculation for 40 TLDs is 1.5%, while these values for all chips do not exceed 5%. PMID:26688801

Development of a TLD mailed system for remote dosimetry audit for (192)Ir HDR and PDR sources.

PubMed

Roué, Amélie; Venselaar, Jack L M; Ferreira, Ivaldo H; Bridier, André; Van Dam, Jan

2007-04-01

In the framework of an ESTRO ESQUIRE project, the BRAPHYQS Physics Network and the EQUAL-ESTRO laboratory have developed a procedure for checking the absorbed dose to water in the vicinity of HDR or PDR sources using a mailed TLD system. The methodology and the materials used in the procedure are based on the existing EQUAL-ESTRO external radiotherapy dose checks. A phantom for TLD postal dose assurance service, adapted to accept catheters from different HDR afterloaders, has been developed. The phantom consists of three PMMA tubes supporting catheters placed at 120 degrees around a central TLD holder. A study on the use of LiF powder type DTL 937 (Philitech) has been performed in order to establish the TLD calibration in dose-to-water at a given distance from (192)Ir source, as well as to determine all correction factors to convert the TLD reading into absorbed dose to water. The dosimetric audit is based on the comparison between the dose to water measured with the TL dosimeter and the dose calculated by the clinical TPS. Results of the audits are classified in four different levels depending on the ratio of the measured dose to the stated dose. The total uncertainty budget in the measurement of the absorbed dose to water using TLD near an (192)Ir HDR source, including TLD reading, correction factors and TLD calibration coefficient, is determined as 3.27% (1s). To validate the procedures, the external audit was first tested among the members of the BRAPHYQS Network. Since November 2004, the test has been made available for use by all European brachytherapy centres. To date, 11 centres have participated in the checks and the results obtained are very encouraging. Nevertheless, one error detected has shown the usefulness of this audit. A method of absorbed dose to water determination in the vicinity of an (192)Ir brachytherapy source was developed for the purpose of a mailed TL dosimetry system. The accuracy of the procedure was determined. This method allows a

Digital Distinction: Badges Add a New Dimension to Adult Learning

ERIC Educational Resources Information Center

Ady, Kellie; Kinsella, Keli; Paynter, Amber

2015-01-01

As a part of a professional learning team, educators are constantly looking for new approaches and designs that promote deeper adult learning. This article describes how educators at Cherry Creek School District in Colorado developed a digital badge system that recognizes the work teachers are doing, supports a culture and climate of celebration,…

A method to minimise the fading effects of LiF:Mg,Ti (TLD-600 and TLD-700) using a pre-heat technique.

PubMed

Lee, YoungJu; Won, Yuho; Kang, Kidoo

2015-04-01

Passive integrating dosemeters [thermoluminescent dosimeter (TLD) and optically stimulated luminescence (OSL)] are the only legally permitted individual dosemeters for occupational external radiation exposure monitoring in Korea. Also its maximum issuing cycle does not exceed 3 months, and the Korean regulations require personal dosemeters for official assessment of external radiation exposure to be issued by an approved or rather an accredited dosimetry service according to ISO/IEC 17025. KHNP (Korea Hydro & Nuclear Power, LTD), a unique operating company of nuclear power plants (NPPs) in Korea, currently has a plan to extend a TLD issuing cycle from 1 to 3 months under the authors' fading error criteria, ±10%. The authors have performed a feasibility study that minimises post-irradiation fading effects within their maximum reading cycle employing pre-heating technique. They repeatedly performed irradiation/reading a bare TLD chip to determine optimum pre-heating conditions by analysing each glow curve. The optimum reading conditions within the maximum reading cycle of 3 months were decided: a pre-heating temperature of 165°C, a pre-heating time of 9 s, a heating rate of 25°C s(-1), a reading temperature of 300°C and an acquisition time of 10 s. The fading result of TLD-600 and TLD-700 carried by newly developed time temperature profile (TTP) showed a much smaller fading effect than that of current TTP. The result showed that the fading error due to a developed TTP resulted in a ∼5% signal loss, whereas a current TTP caused a ∼15% loss. The authors also carried out a legal performance test on newly developed TTP to confirm its possibility as an official dosemeter. The legal performance tests that applied the developed TTP satisfied the criteria for all the test categories. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

5 a day Achievement Badge for African-American Boy Scouts: pilot outcome results.

PubMed

Baranowski, Tom; Baranowski, Janice; Cullen, Karen W; deMoor, Carl; Rittenberry, LaTroy; Hebert, David; Jones, Lovell

2002-03-01

Boy Scouts are an important channel to complement school-based programs to enable boys to eat more fruit, 100% juice, and vegetables (FJV) for chronic disease prevention. The "5 a Day Achievement Badge" program was presented on a pilot study basis to African-American Boy Scout troops in Houston. Troops were the unit of recruitment and random assignment to treatment and control groups. The badge program was presented in Fall 1997 by trained dietitians and included activities to increase availability and accessibility of fruit and vegetables at scouts' homes, increase preferences for vegetables, and train in the preparation of FaSST (fast, simple, safe, and tasty) recipes. Weekly comic books demonstrated and reinforced what scouts were expected to do at home. A weekly newsletter with recipes was sent to parents. The program was revised and presented to the control group in Winter 1998. Two 24-h recalls were the primary assessment tools. Telephone interviews were conducted with parents. The intervention resulted in a 0.8 FJV serving difference (post values of treatment versus control groups with pre value covaried). The changes obtained suggest that the intervention was effective in promoting dietary change. (C)2002 American Health Foundation and Elsevier Science (USA).

Organ radiation exposure with EOS: GATE simulations versus TLD measurements

NASA Astrophysics Data System (ADS)

Clavel, A. H.; Thevenard-Berger, P.; Verdun, F. R.; Létang, J. M.; Darbon, A.

2016-03-01

EOS® is an innovative X-ray imaging system allowing the acquisition of two simultaneous images of a patient in the standing position, during the vertical scan of two orthogonal fan beams. This study aimed to compute organs radiation exposure to a patient, in the particular geometry of this system. Two different positions of the patient in the machine were studied, corresponding to postero-anterior plus left lateral projections (PA-LLAT) and antero-posterior plus right lateral projections (AP-RLAT). To achieve this goal, a Monte-Carlo simulation was developed based on a GATE environment. To model the physical properties of the patient, a computational phantom was produced based on computed tomography scan data of an anthropomorphic phantom. The simulations provided several organs doses, which were compared to previously published dose results measured with Thermo Luminescent Detectors (TLD) in the same conditions and with the same phantom. The simulation results showed a good agreement with measured doses at the TLD locations, for both AP-RLAT and PA-LLAT projections. This study also showed that the organ dose assessed only from a sample of locations, rather than considering the whole organ, introduced significant bias, depending on organs and projections.

Determination of quality parameters from statistical analysis of routine TLD dosimetry data.

PubMed

German, U; Weinstein, M; Pelled, O

2006-01-01

Following the as low as reasonably achievable (ALARA) practice, there is a need to measure very low doses, of the same order of magnitude as the natural background, and the limits of detection of the dosimetry systems. The different contributions of the background signals to the total zero dose reading of thermoluminescence dosemeter (TLD) cards were analysed by using the common basic definitions of statistical indicators: the critical level (L(C)), the detection limit (L(D)) and the determination limit (L(Q)). These key statistical parameters for the system operated at NRC-Negev were quantified, based on the history of readings of the calibration cards in use. The electronic noise seems to play a minor role, but the reading of the Teflon coating (without the presence of a TLD crystal) gave a significant contribution.

VIEW OF JOHN ELDER OF JEANNETTE BADGE NO. 66. BREAKER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF JOHN ELDER OF JEANNETTE BADGE NO. 66. BREAKER FOR GENERAL GLASS COMPANY. TAKEN ON BREAKER FLOOR IN FRONT OF BUCK USED TO HOLD GLASS. WORK EQUIPMENT INCLUDES: HARD HAT, SAFETY GLASSES, PROTECTIVE SLEEVES, LEATHER APRON, GLOVES WITH RUBBER PADS ("METATARSALS") WITH OVER STEEL-TOED SHOES. - Chambers-McKee Window Glass Company, Furnace No. 2, Clay Avenue Extension, Jeannette, Westmoreland County, PA

SU-E-I-09: Application of LiF:Mg,Cu (TLD-100H) Dosimeters for in Diagnostic Radiology

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

Sina, S; Zeinali, B; Karimipourfard, M

Purpose: Accurate dosimetery is very essential in diagnostic radiology. The goal of this study is to verify the application of LiF:Mg,Cu,P (TLD100H) in obtaining the Entrance skin dose (ESD) of patients undergoing diagnostic radiology. The results of dosimetry performed by TLD-100H, were compared with those obtained by TLD100, which is a common dosimeter in diagnostic radiology. Methods: In this study the ESD values were measured using two types of Thermoluminescence dosimeters (TLD-100, and TLD-100H) for 16 patients undergoing diagnostic radiology (lumbar spine imaging). The ESD values were also obtained by putting the two types of TLDs at the surface ofmore » Rando phantom for different imaging techniques and different views (AP, and lateral). The TLD chips were annealed with a standard procedure, and the ECC values for each TLD was obtained by exposing the chips to equal amount of radiation. Each time three TLD chips were covered by thin dark plastic covers, and were put at the surface of the phantom or the patient. The average reading of the three chips was used for obtaining the dose. Results: The results show a close agreement between the dose measuered by the two dosimeters.According to the results of this study, the TLD-100H dosimeters have higher sensitivities (i.e.signal(nc)/dose) than TLD-100.The ESD values varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for measurements. Conclusion: The TLD-100H dosimeters are suggested as effective dosimeters for dosimetry in low dose fields because of their higher sensitivities.« less

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

PubMed Central

Hosseini Pooya, SM; Orouji, T

2014-01-01

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

Analysis and recent advances in gamma heating measurements in MINERVE facility by using TLD and OSLD techniques

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

Amharrak, H.; Di Salvo, J.; Lyoussi, A.

2011-07-01

The objective of this study is to develop nuclear heating measurement methods in Zero Power experimental reactors. This paper presents the analysis of Thermo-Luminescent Detector (TLD) and Optically Stimulated Luminescent Detectors (OSLD) experiments in the UO{sub 2} core of the MINERVE research reactor at the CEA Cadarache. The experimental sources of uncertainties on the gamma dose have been reduced by improving the conditions, as well as the repeatability, of the calibration step for each individual TLD. The interpretation of these measurements needs to take into account calculation of cavity correction factors, related to calibration and irradiation configurations, as well asmore » neutron corrections calculations. These calculations are based on Monte Carlo simulations of neutron-gamma and gamma-electron transport coupled particles. TLD and OSLD are positioned inside aluminum pillboxes. The comparison between calculated and measured integral gamma-ray absorbed doses using TLD, shows that calculation slightly overestimates the measurement with a C/E value equal to 1.05 {+-} 5.3 % (k = 2). By using OSLD, the calculation slightly underestimates the measurement with a C/E value equal to 0.96 {+-} 7.0% (k = 2. (authors)« less

Ge and B doped collapsed photonic crystal optical fibre, a potential TLD material for low dose measurements

NASA Astrophysics Data System (ADS)

Rozaila, Z. Siti; Alyahyawi, Amjad; Khandaker, M. U.; Amin, Y. M.; Bradley, D. A.; Maah, M. J.

2016-09-01

Offering a number of advantageous features, tailor-made silica-based fibres are attracting attention as thermoluminesence (TL) dosimeters. We have performed a detailed study of the TL properties of Ge-doped and Ge-B-doped collapsed photonic crystal fibres (PCFc), most particularly with regard to their potential use for the environmental and X-ray diagnostic dose monitoring. Extrinsic doping and defects generated by strain at the fused inner walls of the collapsed fibres result in the PCFc-Ge-B and PCFc-Ge fibres producing markedly greater TL response than that of the phosphor-based dosimeter TLD-100, by some 9 and 7×, respectively. The linearity of TL yield has been investigated for X-ray doses from 0.5 mGy to 10 mGy. For a dose of 1 Gy, the energy response of the PCFs and TLD-100 has been studied using X-rays generated at accelerating potentials from 20 kVp through to 200 kVp and for the 1.25 MeV mean gamma-ray energy from 60Co. The effective atomic number , Zeffof PCFc-Ge and PCFc-Ge-B was estimated to be 12.5 and 14.4, respectively. Some 35 days post-irradiation, fading of the stored TL signal from PCFc-Ge-B and PCFc-Ge were found to be ∼15% and 20% respectively, with mean loss in TL emission of 0.4-0.5% per day. The present doped-silica collapsed PCFs provide greatly improved TLD performance compared to that of previous fibre designs and phosphor-based TLD-100.

Towards in vivo TLD dosimetry in mammography.

PubMed

Warren-Forward, H M; Duggan, L

2004-05-01

While phantoms are used for quality control assessment of the mammography unit, in vivo dose measurements are necessary to account for the variation in size and composition of the female breast. The use of thermoluminescent dosimeters (TLDs) in mammography has been limited due to TLD visibility. The aim of this current investigation was to access the suitability of a paper-thin LiF:Mg,Cu,P TLD (GR-200F) for in vivo dosimetric mammography measurements. The visibility of GR-200F has been directly compared with LiF:Mg,Cu,P TLDs (GR-200A) using a number of commercially available phantoms. The phantoms of thickness 2-5 cm were imaged over the range of tube potentials (24-28 kVp) used clinically. Both types of TLD were placed on the surface of the phantoms allowing assessment of visibility, entrance surface dose (ESD) and field homogeneity. In vivo assessment of ESD and visibility was also carried out on a volunteer undergoing a routine mammography examination. The positions of the GR-200F TLDs were not identified either on the image of the Leeds TOR(MAM) phantom or the patient mammograms. The average ESD for the Leeds phantom was 8.8 mGy, while the patient ESD was 13 mGy. It is now possible to perform in vivo measurements with the potential of increasing the accuracy of the doses measured for women that do not conform to a standard breast thickness or density.

Developmental roles of the BMP1/TLD metalloproteinases.

PubMed

Ge, Gaoxiang; Greenspan, Daniel S

2006-03-01

The astacin family (M12A) of the metzincin subclan MA(M) of metalloproteinases has been detected in developing and mature individuals of species that range from hydra to humans. Functions of this family of metalloproteinase vary from digestive degradation of polypeptides, to biosynthetic processing of extracellular proteins, to activation of growth factors. This review will focus on a small subgroup of the astacin family; the bone morphogenetic protein 1 (BMP1)/Tolloid (TLD)-like metalloproteinases. In vertebrates, the BMP1/TLD-like metalloproteinases play key roles in regulating formation of the extracellular matrix (ECM) via biosynthetic processing of various precursor proteins into mature functional enzymes, structural proteins, and proteins involved in initiating mineralization of the ECM of hard tissues. Roles in ECM formation include: processing of the C-propeptides of procollagens types I-III, to yield the major fibrous components of vertebrate ECM; proteolytic activation of the enzyme lysyl oxidase, necessary to formation of covalent cross-links in collagen and elastic fibers; processing of NH2-terminal globular domains and C-propeptides of types V and XI procollagen chains to yield monomers that are incorporated into and control the diameters of collagen type I and II fibrils, respectively; processing of precursors for laminin 5 and collagen type VII, both of which are involved in securing epidermis to underlying dermis; and maturation of small leucine-rich proteoglycans. The BMP1/TLD-related metalloproteinases are also capable of activating the vertebrate transforming growth factor-beta (TGF-beta)-like "chalones" growth differentiation factor 8 (GDF8, also known as myostatin), and GDF11 (also known as BMP11), involved in negative feedback inhibition of muscle and neural tissue growth, respectively; by freeing them from noncovalent latent complexes with their cleaved prodomains. BMP1/TLD-like proteinases also liberate the vertebrate TGF

Digital Badges for Staff Training: Motivate Employees to Learn with Micro-Credentials

ERIC Educational Resources Information Center

Copenhaver, Kimberly; Pritchard, Liz

2017-01-01

Integrating micro-credentialing into employee training programs offers libraries an innovative and individualized way to recognize and certify learning and achievement. Digital badges provide a low-cost initiative to support learning benefiting both the individual and institution, offering evidence of skill development that transcends the library…

TLD extrapolation for skin dose determination in vivo.

PubMed

Kron, T; Butson, M; Hunt, F; Denham, J

1996-11-01

Prediction of skin reactions requires knowledge of the dose at various depths in the human skin. Using thermoluminescence dosimeters of three different thicknesses, the dose can be extrapolated to the surface and interpolated between the different depths. A TLD holder was designed for these TLD extrapolation measurements on patients during treatment which allowed measurements of entrance and exit skin dose with a day to day variability of +/-7% (S.D. of mean reading). In a pilot study on 18 patients undergoing breast irradiation, it was found that the angle of incidence of the radiation beam is the most significant factor influencing skin entrance dose. In most of these measurements the beam exit dose contributed 50% more to the surface dose than the entrance dose.

Calculated and TLD-based absorbed dose estimates for I-131-labeled 3F8 monoclonal antibody in a human neuroblastoma xenograft nude mouse model.

PubMed

Ugur, O; Scott, A M; Kostakoglu, L; Hui, T E; Masterson, M E; Febo, R; Sgouros, G; Rosa, E; Mehta, B M; Fisher, D R

1995-01-01

Preclinical evaluation of the therapeutic potential of radiolabeled antibodies is commonly performed in a xenografted nude mouse model. To assess therapeutic efficacy it is important to estimate the absorbed dose to the tumor and normal tissues of the nude mouse. The current study was designed to accurately measure radiation does to human neuroblastoma xenografts and normal organs in nude mice treated with I-131-labeled 3F8 monoclonal antibody (MoAb) against disialoganglioside GD2 antigen. Absorbed dose estimates were obtained using two different approaches: (1) measurement with teflon-imbedded CaSO4:Dy mini-thermoluminescent dosimeters (TLDs) and (2) calculations using mouse S-factors. The calculated total dose to tumor one week after i.v. injection of the 50 microCi I-131-3F8 MoAb was 604 cGy. The corresponding decay corrected and not corrected TLD measurements were 109 +/- 9 and 48.7 +/- 3.4 cGy respectively. The calculated to TLD-derived dose ratios for tumor ranged from 6.1 at 24 h to 5.5 at 1 week. The light output fading rate was found to depend upon the tissue type within which the TLDs were implanted. The decay rate in tumor, muscle, subcutaneous tissue and in vitro, were 9.5, 5.0, 3.7 and 0.67% per day, respectively. We have demonstrated that the type of tissue in which the TLD was implanted strongly influenced the in vivo decay of light output. Even with decay correction, a significant discrepancy was observed between MIRD-based calculated and CaSO4:Dy mini-TLD measured absorbed doses. Batch dependence, pH of the tumor or other variables associated with TLDs which are not as yet well known may account for this discrepancy.

Learning Analytics and Digital Badges: Potential Impact on Student Retention in Higher Education

ERIC Educational Resources Information Center

Mah, Dana-Kristin

2016-01-01

Learning analytics and digital badges are emerging research fields in educational science. They both show promise for enhancing student retention in higher education, where withdrawals prior to degree completion remain at about 30% in Organisation for Economic Cooperation and Development member countries. This integrative review provides an…

NOTE: Monte Carlo simulation of correction factors for IAEA TLD holders

NASA Astrophysics Data System (ADS)

Hultqvist, Martha; Fernández-Varea, José M.; Izewska, Joanna

2010-03-01

The IAEA standard thermoluminescent dosimeter (TLD) holder has been developed for the IAEA/WHO TLD postal dose program for audits of high-energy photon beams, and it is also employed by the ESTRO-QUALity assurance network (EQUAL) and several national TLD audit networks. Factors correcting for the influence of the holder on the TL signal under reference conditions have been calculated in the present work from Monte Carlo simulations with the PENELOPE code for 60Co γ-rays and 4, 6, 10, 15, 18 and 25 MV photon beams. The simulation results are around 0.2% smaller than measured factors reported in the literature, but well within the combined standard uncertainties. The present study supports the use of the experimentally obtained holder correction factors in the determination of the absorbed dose to water from the TL readings; the factors calculated by means of Monte Carlo simulations may be adopted for the cases where there are no measured data.

Perceptions and Uses of Digital Badges for Professional Learning Development in Higher Education

ERIC Educational Resources Information Center

Dyjur, Patti; Lindstrom, Gabrielle

2017-01-01

Few instructors in higher education have completed a formal teaching program and, therefore, rely on informal professional development opportunities to enhance their teaching practice. Micro-credentialing in the form of digital badges is one way in which instructors can document their non-credit learning and accomplishments. This mixed methods…

SU-E-T-172: Characterization of TLD-100 (LiF:Mg,Ti) Microcube Energy Response in a Cylindrical Chamber Phantom

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

Desai, V; Hammer, C; Kunugi, K

Purpose: To characterize the energy response of TLD-100 microcubes inside a Virtual Water chamber phantom. Methods: Four TLD microcubes were placed inside a water-proof Virtual Water (VW) chamber phantom and irradiated to a known dose on a Varian linac in a 1D water tank. These chamber phantoms were then replaced by TLD-100 chips inside a separate VW paddle and irradiated to the same dose. Each energy response reading was calculated as light output per unit dose in nC/cGy and normalized to a calibration set irradiated to the same dose in 60Co. The differences in response between the TLD chips andmore » microcubes were then analyzed. Results: Across all energies, the average microcube response was less sensitive to energy than the average chip response with both falling consistently within 2.8% of previously established values in the literature Conclusion: TLD microcubes showed a lower average sensitivity to energy than their TLD chip counterparts. The use of TLD-100 microcubes inside the chamber phantom was validated against TLD-100 chips inside of VW paddles.« less

Comparative study on skin dose measurement using MOSFET and TLD for pediatric patients with acute lymphatic leukemia.

PubMed

Al-Mohammed, Huda I; Mahyoub, Fareed H; Moftah, Belal A

2010-07-01

The object of this study was to compare the difference of skin dose measured in patients with acute lymphatic leukemia (ALL) treated with total body irradiation (TBI) using metal oxide semiconductor field-effect transistors (mobile MOSFET dose verification system (TN-RD-70-W) and thermoluminescent dosimeters (TLD-100 chips, Harshaw/ Bicron, OH, USA). Because TLD has been the most-commonly used technique in the skin dose measurement of TBI, the aim of the present study is to prove the benefit of using the mobile MOSFET (metal oxide semiconductor field effect transistor) dosimeter, for entrance dose measurements during the total body irradiation (TBI) over thermoluminescent dosimeters (TLD). The measurements involved 10 pediatric patients ages between 3 and 14 years. Thermoluminescent dosimeters and MOSFET dosimetry were performed at 9 different anatomic sites on each patient. The present results show there is a variation between skin dose measured with MOSFET and TLD in all patients, and for every anatomic site selected, there is no significant difference in the dose delivered using MOSFET as compared to the prescribed dose. However, there is a significant difference for every anatomic site using TLD compared with either the prescribed dose or MOSFET. The results indicate that the dosimeter measurements using the MOSFET gave precise measurements of prescribed dose. However, TLD measurement showed significant increased skin dose of cGy as compared to either prescribed dose or MOSFET group. MOSFET dosimeters provide superior dose accuracy for skin dose measurement in TBI as compared with TLD.

A LC-MS/MS method for the determination of BADGE-related and BFDGE-related compounds in canned fish food samples based on the formation of [M+NH(4)](+) aducts.

PubMed

Míguez, J; Herrero, C; Quintás, I; Rodríguez, C; Gigosos, P G; Mariz, O C

2012-12-01

A new and simple liquid chromatography tandem mass-spectrometry method for the determination of different bisphenol A (BPA) derivatives such as bisphenol A diglycidyl ether (BADGE), bisphenol F diglycidyl ether (BFDGE) and their reaction products with water and hydrochloric acid in different fish food products was developed. The extraction procedure and the chromatographic conditions were optimised for complex food matrices such as fish products. Food samples were homogenised and extracted with a 1:1 solution of acetonitrile-hexane, the solvent was eliminated in a N(2) stream and the extract was reconstituted with 0.5mL of a 0.01M solution of ammonium formate. The sample solution obtained was directly measured by LC-MS/MS without any further purification under the developed conditions. The use of a mobile phase composed by ammonium formate-methanol in a binary gradient mode produced [M+NH(4)](+) aducts for the different BADGEs and BFDGEs. These aduct's fragmentations were employed for the LC-MS/MS quantification of BPA derivatives in canned fish samples. The results of the validation were appropriate: the method was linear for BADGE and its hydrolysed derivatives up to 1000μgkg(-1), for the remaining compounds linearity achieved up to 100μgkg(-1). Quantification limits were in the range 2-10μgkg(-1). RSD (intra and inter-day) was 6-12% and the recovery was comprised between 89% and 109%. Under the optimised conditions, the chromatographic separation was performed in 8min per sample. The method was applied to the determination of BADGE, BFDGE and their reaction products in different samples of canned fish from Spanish origin. Migration results obtained were in compliance with the EU regulations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Skin dose measurements using MOSFET and TLD for head and neck patients treated with tomotherapy.

PubMed

Kinhikar, Rajesh A; Murthy, Vedang; Goel, Vineeta; Tambe, Chandrashekar M; Dhote, Dipak S; Deshpande, Deepak D

2009-09-01

The purpose of this work was to estimate skin dose for the patients treated with tomotherapy using metal oxide semiconductor field-effect transistors (MOSFETs) and thermoluminescent dosimeters (TLDs). In vivo measurements were performed for two head and neck patients treated with tomotherapy and compared to TLD measurements. The measurements were subsequently carried out for five days to estimate the inter-fraction deviations in MOSFET measurements. The variation between skin dose measured with MOSFET and TLD for first patient was 2.2%. Similarly, the variation of 2.3% was observed between skin dose measured with MOSFET and TLD for second patient. The tomotherapy treatment planning system overestimated the skin dose as much as by 10-12% when compared to both MOSFET and TLD. However, the MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1% to 1.4%. MOSFETs may be used as a viable dosimeter for measuring skin dose in areas where the treatment planning system may not be accurate.

Exploring relationship between face-to-face interaction and team performance using wearable sensor badges.

PubMed

Watanabe, Jun-ichiro; Ishibashi, Nozomu; Yano, Kazuo

2014-01-01

Quantitative analyses of human-generated data collected in various fields have uncovered many patterns of complex human behaviors. However, thus far the quantitative evaluation of the relationship between the physical behaviors of employees and their performance has been inadequate. Here, we present findings demonstrating the significant relationship between the physical behaviors of employees and their performance via experiments we conducted in inbound call centers while the employees wore sensor badges. There were two main findings. First, we found that face-to-face interaction among telecommunicators and the frequency of their bodily movements caused by the face-to-face interaction had a significant correlation with the entire call center performance, which we measured as "Calls per Hour." Second, our trial to activate face-to-face interaction on the basis of data collected by the wearable sensor badges the employees wore significantly increased their performance. These results demonstrate quantitatively that human-human interaction in the physical world plays an important role in team performance.

Exploring Relationship between Face-to-Face Interaction and Team Performance Using Wearable Sensor Badges

PubMed Central

Watanabe, Jun-ichiro; Ishibashi, Nozomu; Yano, Kazuo

2014-01-01

Quantitative analyses of human-generated data collected in various fields have uncovered many patterns of complex human behaviors. However, thus far the quantitative evaluation of the relationship between the physical behaviors of employees and their performance has been inadequate. Here, we present findings demonstrating the significant relationship between the physical behaviors of employees and their performance via experiments we conducted in inbound call centers while the employees wore sensor badges. There were two main findings. First, we found that face-to-face interaction among telecommunicators and the frequency of their bodily movements caused by the face-to-face interaction had a significant correlation with the entire call center performance, which we measured as “Calls per Hour.” Second, our trial to activate face-to-face interaction on the basis of data collected by the wearable sensor badges the employees wore significantly increased their performance. These results demonstrate quantitatively that human-human interaction in the physical world plays an important role in team performance. PMID:25501748

Measurements of occupational exposure for a technologist performing 18F FDG PET scans.

PubMed

Biran, Talma; Weininger, Jolie; Malchi, Shalom; Marciano, Rami; Chisin, Roland

2004-11-01

Radiation doses to one PET technologist performing 100 18F FDG (18F fluorodeoxyglucose) imaging procedures were measured in a clinical setting using two types of thermoluminescent dosimeter (TLD) badges, one finger-ring TLD and one electronic pocket dosimeter (EPD). 18F FDG was handled either with unshielded or with viewing window tungsten shielded syringes. The resulting doses using unshielded syringes were 13.8 +/- 0.8 microSv/370 MBq and 14.3 +/- 0.4 microSv/370 MBq, measured with TLD 100 and with TLD 700H/600H, respectively. For the same series of measurements, the doses obtained using shielded syringes were 10.7 +/- 0.4 microSv/370 MBq and 7.2 +/- 2.1 microSv/370 MBq with TLD700H/600H and with EPD, respectively. The dose to the right hand from shielded syringes was 69.3 +/- 5.5 microSv/370 MBq. All these values are within the ICRP recommended dose limits. Extrapolated to 725 examinations per year, the resulting effective dose measured with TLD would be 10 mSv with unshielded and 7.5 mSv with shielded syringes, respectively (25% dose reduction). The doses measured by TLD were consistently higher than those measured by EPD, suggesting that EPD measurements might underestimate occupational doses.

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market.

PubMed

Uematsu, Y; Hirata, K; Suzuki, K; Iida, K; Saito, K

2001-02-01

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GC-MS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1 mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl anti BFDGE.HCl.H2O at a level of 1.5 mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.

Boy Scout 5-a-day badge: Outcome results of a troop and internet intervention

USDA-ARS?s Scientific Manuscript database

The effects of a Boy Scout Five-A-Day Badge program on fruit-juice (FJ) and low fat vegetable (LV) consumption were evaluated using a two-condition (treatment, active-attention placebo-control) group randomized trial, with 3 data collection periods (baseline, immediate post, 6-month post). Forty-two...

The Digital Pipetting Badge: A Method to Improve Student Hands-On Laboratory Skills

ERIC Educational Resources Information Center

Towns, Marcy; Harwood, Cynthia J.; Robertshaw, M. Brooke; Fish, Jason; O'Shea, Kevin

2015-01-01

An evidence centered design approach was used to develop, implement, and assess a novel and innovative digital pipetting badge using Purdue's Passport system. Each student in a large lecture course created a video demonstrating how to use a 10 mL pipet to dispense liquid. The video was uploaded into the Passport system, which allowed instructors…

TLD postal dose intercomparison for megavoltage units in Poland.

PubMed

Izewska, J; Gajewski, R; Gwiazdowska, B; Kania, M; Rostkowska, J

1995-08-01

The aim of the TLD pilot study was to investigate and to reduce the uncertainties involved in the measurements of absorbed dose and to improve the consistency in dose determination in the regional radiotherapy centres in Poland. The intercomparison was organized by the SSDL. It covered absorbed dose measurements under reference conditions for Co-60, high energy X-rays and electron beams. LiF powder type MT-N was used for the irradiations and read with the Harshaw TLD reader model 2000B/2000C. The TLD system was set up and an analysis of the factors influencing the accuracy of absorbed dose measurements with TL-detectors was performed to evaluate and minimize the measurement uncertainty. A fading not exceeding 2% in 12 weeks was found. The relative energy correction factor did not exceed 3% for X-rays in the range 4-15 MV, and 4% for electron beams between 6 and 20 MeV. A total of 34 beams was checked. Deviation of +/- 3.5% stated and evaluated dose was considered acceptable for photons and +/- 5% for electron beams. The results for Co-60, high energy X-rays and electron beams showed that there were two, three and no centres, respectively, beyond acceptance levels. The sources of errors for all deviations out of this range were thoroughly investigated, discussed and corrected, however two deviations remained unexplained. The pilot study resulted in an improvement of the accuracy and consistency of dosimetry in Poland.

Environmental Science and Engineering Merit Badges: An Exploratory Case Study of a Non-Formal Science Education Program and the U.S. Scientific and Engineering Practices

ERIC Educational Resources Information Center

Vick, Matthew E.; Garvey, Michael P.

2016-01-01

The Boy Scouts of America's Environmental Science and Engineering merit badges are two of their over 120 merit badges offered as a part of a non-formal educational program to U.S. boys. The Scientific and Engineering Practices of the U.S. Next Generation Science Standards provide a vision of science education that includes integrating eight…

SU-E-T-137: The Response of TLD-100 in Mixed Fields of Photons and Electrons.

PubMed

Lawless, M; Junell, S; Hammer, C; DeWerd, L

2012-06-01

Thermoluminescent dosimeters are used routinely for dosimetric measurements of photon and electron fields. However, no work has been published characterizing TLDs for use in combined photon and electron fields. This work investigates the response of TLD-100 (LiF:Mg,Ti) in mixed fields of photon and electron beam qualities. TLDs were irradiated in a 6 MV photon beam, 6 MeV electron beam, and a NIST traceable cobalt-60 beam. TLDs were also irradiated in a mixed field of the electron and photon beams. All irradiations were normalized to absorbed dose to water as defined in the AAPM TG-51 report. The average response per dose (nC/Gy) for each linac beam quality was normalized to the average response per dose of the TLDs irradiated by the cobalt-60 standard.Irradiations were performed in a water tank and a Virtual Water™ phantom. Two TLD dose calibration curves for determining absorbed dose to water were generated using photon and electron field TLD response data. These individual beam quality dose calibration curves were applied to the TLDs irradiated in the mixed field. The TLD response in the mixed field was less sensitive than the response in the photon field and more sensitive than the response in the electron field. TLD determination of dose in the mixed field using the dose calibration curve generated by TLDs irradiated by photons resulted in an underestimation of the delivered dose, while the use of a dose calibration curve generated using electrons resulted in an overestimation of the delivered dose. The relative response of TLD-100 in mixed fields fell consistently between the photon nd electron relative responses. When using TLD-100 in mixed fields, the user must account for this intermediate response to avoid an over- or underestimation of the dose due to calibration in a single photon or electron field. © 2012 American Association of Physicists in Medicine.

Comparison of TLD calibration methods for  192Ir dosimetry

PubMed Central

Butler, Duncan J.; Wilfert, Lisa; Ebert, Martin A.; Todd, Stephen P.; Hayton, Anna J.M.; Kron, Tomas

2013-01-01

For the purpose of dose measurement using a high‐dose rate  192Ir source, four methods of thermoluminescent dosimeter (TLD) calibration were investigated. Three of the four calibration methods used the  192Ir source. Dwell times were calculated to deliver 1 Gy to the TLDs irradiated either in air or water. Dwell time calculations were confirmed by direct measurement using an ionization chamber. The fourth method of calibration used 6 MV photons from a medical linear accelerator, and an energy correction factor was applied to account for the difference in sensitivity of the TLDs in  192Ir and 6 M V. The results of the four TLD calibration methods are presented in terms of the results of a brachytherapy audit where seven Australian centers irradiated three sets of TLDs in a water phantom. The results were in agreement within estimated uncertainties when the TLDs were calibrated with the  192Ir source. Calibrating TLDs in a phantom similar to that used for the audit proved to be the most practical method and provided the greatest confidence in measured dose. When calibrated using 6 MV photons, the TLD results were consistently higher than the  192Ir−calibrated TLDs, suggesting this method does not fully correct for the response of the TLDs when irradiated in the audit phantom. PACS number: 87 PMID:23318392

Personalized Workplace Learning: An Exploratory Study on Digital Badging within a Teacher Professional Development Program

ERIC Educational Resources Information Center

Gamrat, Christopher; Zimmerman, Heather Toomey; Dudek, Jaclyn; Peck, Kyle

2014-01-01

To provide customized workplace learning opportunities, a digital badge system was designed by a university, governmental agency and national professional association to support teachers' implementation of professional development (PD). Teacher Learning Journeys (TLJ) is an approach that allows for teachers to customize their PD experience to…

The Dusk Chorus from an Owl Perspective: Eagle Owls Vocalize When Their White Throat Badge Contrasts Most

PubMed Central

Penteriani, Vincenzo; Delgado, Maria del Mar

2009-01-01

Background An impressive number of studies have investigated bird vocal displays, and many of them have tried to explain the widespread phenomenon of the so-called dawn and dusk chorus, the sunrise and sunset peaks in bird song output. As many as twelve non-exclusive hypotheses have been proposed to explain why twilight peaks in vocal display might be advantageous; but, even after more than two decades of study, the basis underlying the dusk and dawn chorus is still unclear. Moreover, to date, the majority of studies on this topic have focused on songbirds. Methodology/Principal Findings We investigate here a novel hypothesis on why nocturnal birds with patches of white feathers call at twilight. We propose that white plumage patches and the timing of visual signaling have co-evolved to maximize the effectiveness of social communication such as the dusk chorus. This hypothesis centers on the recent discovery that eagle owls can adopt specific forms of visual signaling and is supported by the observation that adult eagle owls possess a white throat badge that is only visible during vocal displays. By monitoring the calling of eagle owls at dusk, a peak time for bird call output, we found that white throat badges contrasted most with the surrounding background during the owls' twilight chorusing. Conclusions/Significance Crepuscular and nocturnal species appear to have evolved white patches that, shown in association with vocal displays, allow them to communicate in dark surroundings. The evolution of a white badge that operates jointly with call displays at dawn and dusk may be relevant to the eagle owls' social dynamics. Our explanation for the dusk chorus may possibly represent an overlooked but common pattern of signaling among crepuscular and nocturnal birds that combine patches of white feathers with twilight displays. Furthermore, our findings could be relevant to songbirds that breed in dark forest habitats and have contrasting white badges, as well as birds

The dusk chorus from an owl perspective: eagle owls vocalize when their white throat badge contrasts most.

PubMed

Penteriani, Vincenzo; Delgado, Maria del Mar

2009-01-01

An impressive number of studies have investigated bird vocal displays, and many of them have tried to explain the widespread phenomenon of the so-called dawn and dusk chorus, the sunrise and sunset peaks in bird song output. As many as twelve non-exclusive hypotheses have been proposed to explain why twilight peaks in vocal display might be advantageous; but, even after more than two decades of study, the basis underlying the dusk and dawn chorus is still unclear. Moreover, to date, the majority of studies on this topic have focused on songbirds. We investigate here a novel hypothesis on why nocturnal birds with patches of white feathers call at twilight. We propose that white plumage patches and the timing of visual signaling have co-evolved to maximize the effectiveness of social communication such as the dusk chorus. This hypothesis centers on the recent discovery that eagle owls can adopt specific forms of visual signaling and is supported by the observation that adult eagle owls possess a white throat badge that is only visible during vocal displays. By monitoring the calling of eagle owls at dusk, a peak time for bird call output, we found that white throat badges contrasted most with the surrounding background during the owls' twilight chorusing. Crepuscular and nocturnal species appear to have evolved white patches that, shown in association with vocal displays, allow them to communicate in dark surroundings. The evolution of a white badge that operates jointly with call displays at dawn and dusk may be relevant to the eagle owls' social dynamics. Our explanation for the dusk chorus may possibly represent an overlooked but common pattern of signaling among crepuscular and nocturnal birds that combine patches of white feathers with twilight displays. Furthermore, our findings could be relevant to songbirds that breed in dark forest habitats and have contrasting white badges, as well as birds living in open habitats and showing contrasting bars.

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

Dose estimation of eye lens for interventional procedures in diagnosis

NASA Astrophysics Data System (ADS)

Liu, Yu-Rong; Huang, Chia-Yu; Hsu, Ching-Han; Hsu, Fang-Yuh

2017-11-01

The International Commission on Radiological Protection (ICRP) recommended that the equivalent dose limit for the lens of the eye be decreased from 150 mSv/y (ICRP, 2007) to 20 mSv/y averaged over five years (ICRP, 2011). How to accurately measure the eye-lens dose has, therefore, been an issue of interest recently. Interventional radiologists are at a higher risk of radiation-induced eye injury, such as cataracts, than all other occupational radiation workers. The main objective of this study is to investigate the relationship between the doses to the eye lenses of interventional radiologists measured by different commercial eye-lens dosimeters. This study measured a reference eye-lens dose, which involved placing thermoluminescent dosimeter (TLD) chips at the surface of the eye of the Rando Phantom, and the TLD chips were covered by a 3-mm-thick tissue-equivalent bolus. Commercial eye-lens dosimeters, such as a headband dosimeter and standard personnel dose badges, were placed at the positions recommended by the manufacturers. The results show that the personnel dose badge is not an appropriate dosimeter for evaluating eye-lens dose. Dose deviations for different dosimeters are discussed and presented in this study.

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

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

TLD assessment of mouse dosimetry during microCT imaging

PubMed Central

Figueroa, Said Daibes; Winkelmann, Christopher T.; Miller, William H.; Volkert, Wynn A.; Hoffman, Timothy J.

2008-01-01

Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiation dose delivered during a standard microCT scan. Radiation dose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an 80 kVp x-ray source, with 0.5 mm Al filtration and a total of 54 mA s for a full 360 deg rotation of the unit. The TLD data were validated using a 3.2 cm3 CT ion chamber probe. TLD results showed a single microCT scan air kerma of 78.0±5.0 mGy when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of 92.0±6.0 mGy without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of 81.0±4.0 mGy and 97.0±5.0 mGy with and without the PMMA anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ radiation absorbed dose of 76.0±5.0 mGy. The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality. PMID:18841837

The interpretability of doctor identification badges in UK hospitals: a survey of nurses and patients.

PubMed

Hickerton, Bethan C; Fitzgerald, Daniel John; Perry, Elizabeth; De Bolla, Alan R

2014-07-01

Hospital badges have multiple important purposes, but their essential role remains the clear identification of the bearer, including their professional status. The modernisation of medical careers in the National Health Service has changed terminology dramatically, resulting in a plethora of new job titles emerging among both doctors and nurses. To determine whether the new or old terminology allowed clearer identification of medical doctors by patients and nurses. We replicated 11 identification badges used in the Royal Cornwall Hospital and Wrexham Maelor Hospital, both current and before the introduction of new medical training terminology. Data were collected from 114 patients and 67 nurses, by asking them to (1) identify which name badges represented doctors and (2) rank them in order of seniority. Only 11% of patients and 60% of nurses identified a 'Foundation Year 1 Trainee' as a qualified medical doctor. Indeed, only 'General Practice Vocational Trainee' and 'Consultant' were both readily identifiable as qualified doctors to both patients and nurses. Ranking was also a problem, with only 19% of patients and 45% of nurses able to correctly grade medical doctors using the current terminology. The old terminology allowed more accurate identification by nurses, with over 80% successfully ranking and marking the title appropriately. Current terminology is a source of confusion to both patients and members of the immediate medical care team, with nurses unable to correctly identify medical doctors. Our study indicates that a review of terminology is necessary to ensure patients, and staff, are able to communicate effectively. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Relative Efficiency of TLD-100 to Linear Energy Transfer Radiation: Correction to Astronaut Absorbed Dose

NASA Technical Reports Server (NTRS)

Badhwar, Gautam D.; Cash, B. L.; Semones, E. J.; Yasuda, H.; Fujitaka, K.

1999-01-01

Response of thermoluminescent detectors (TLD-100) to high linear energy transfer (LET) particles has been studied using helium, carbon, silicon, and iron ions from the Heavy Ion Medical Accelerator at Chiba (Japan), iron ions from the Brookhaven National Laboratory (NY) Alternate Gradient Synchrotron, and 53, 134, 185, and 232 MeV protons from the Loma Linda accelerator. Using the measured relative (to (137)Cs dose efficiency, and measured LET spectra from a tissue equivalent proportional counter (TEPC) on 20 Space Shuttle flights, and 7 Mir flights, the underestimation of absorbed dose by these detectors has been evaluated. The dose underestimation is between 15-20% depending upon the flight inclination and shielding location. This has been confirmed by direct correlation of measured dose by TEPC and TLD-100 at a low shielded location in the Shuttle mid-deck. A comparison of efficiency- LET data with a compilation of similar data from TLD-700, shows that shapes of the two curves are nearly identical, but that the TLD-100 curve is systematically lower by about 13%, and is the major cause of dose underestimation. These results strongly suggest that TLDs used for crew dose estimation be regularly calibrated using heavy ions.

Verification of an on line in vivo semiconductor dosimetry system for TBI with two TLD procedures.

PubMed

Sánchez-Doblado, F; Terrón, J A; Sánchez-Nieto, B; Arráns, R; Errazquin, L; Biggs, D; Lee, C; Núñez, L; Delgado, A; Muñiz, J L

1995-01-01

This work presents the verification of an on line in vivo dosimetry system based on semiconductors. Software and hardware has been designed to convert the diode signal into absorbed dose. Final verification was made in the form of an intercomparison with two independent thermoluminiscent (TLD) dosimetry systems, under TBI conditions.

Thermal and Optical Characteristics of Defect Centers in Irradiated TLD-100 Dosimeters.

NASA Astrophysics Data System (ADS)

Sadeghi-Zamani, Hossein

Sensitivity loss of a sensitized LiF:Mg,Ti,Al (TLD-100) dosimeter subject to repeated standard 673 K thermal treatments has been a major problem in radiation dosimetry. The cause for this loss in radiation response of the dosimeters has not been understood. If a used TLD is not annealed at an elevated temperature prior to reuse, there are residual deep electron trap centers still present in the dosimeter. These defect centers will interact with new incoming radiation and produce thermoluminescent trap centers. This will introduce a significant error in low dose measurements. In this research, first, thermal and optical characteristics of various defect centers produced in an irradiated TLD-100 single crystal were investigated and then an improved pre-irradiation isothermal/optical treatment process was introduced to bleach the TLD dosimeters prior to reuse and reduce the loss of sensitivity of sensitized dosimeter. Thermoluminescent materials were irradiated by gamma-rays from Co-60 source to produce sufficient concentration of various defect centers, then the crystals were heated or exposed to UV light at different temperature to change the concentration of various defect centers. The change in concentration of each trap center was determined by measuring the change in absorbance of light at a fixed photon energy as a function of temperature. The thermal activation energy and the frequency factor for each trap center were evaluated assuming a first order kinetic model over a specified temperature range. The value of activation energy and the frequency factor for Z_2 ^', Z_2, Z_3, and F trap centers in TLD-100 single crystals were found to be 1.49 +/- 0.04 eV, 4.76 times 10 ^{15} sec^{ -1}, 2.23 +/- 0.02 eV, 1.65 times 10^{23 } sec^{-1}; 3.01 +/- 0.02 eV, 2.90 times 10^{17} sec ^{-1}; and 2.81 +/- 0.08 eV, 5.43 times 10 ^{17} sec^{ -1}; respectively. After a correlation was made between the trap centers and TL glow peaks, kinetic parameters obtained from absorption

Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method.

PubMed

HosseiniAliabadi, S J; Hosseini Pooya, S M; Afarideh, H; Mianji, F

2015-06-01

The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. This system can be utilized in large scale environmental monitoring with a higher accuracy.

Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method

PubMed Central

HosseiniAliabadi, S. J.; Hosseini Pooya, S. M.; Afarideh, H.; Mianji, F.

2015-01-01

Introduction The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. Objective A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Method Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. Result The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. Conclusion This system can be utilized in large scale environmental monitoring with a higher accuracy. PMID:26157729

Relative Efficiency of TLD-100 to High Linear Energy Transfer Radiation: Correction to Astronaut Absorbed Dose

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Cash, B. L.; Semones, E. J.; Yasuda, H.; Fujitaka, K.

1999-01-01

Response of thermoluminescent detectors (TLD-100) to high linear energy transfer (LET) particles has been studied using helium, carbon, silicon, and iron ions from the Heavy Ion Medical Accelerator at Chiba (Japan), iron ions from the Brookhaven National Laboratory (NY) Alternate Gradient Synchrotron, and 53, 134, 185, and 232 MeV protons from the Loma Linda accelerator. Using the measured relative (to 137Cs) dose efficiency, and measured LET spectra from a tissue equivalent proportional counter (TEPC) on 20 Space Shuttle flights, and 7 Mir flights, the underestimation of absorbed dose by these detectors has been evaluated. The dose underestimation is between 15-20% depending upon the flight inclination and shielding location. This has been confirmed by direct correlation of measured dose by TEPC and TLD-100 at a low shielded location in the Shuttle mid-deck. A comparison of efficiency- LET data with a compilation of similar data from TLD-700, shows that shapes of the two curves are nearly identical, but that the TLD-100 curve is systematically lower by about 13%, and is the major cause of dose underestimation. These results strongly suggest that TLDs used for crew dose estimation be regularly calibrated using heavy ions.

A fast and sensitive TLD method for measurement of energy and homogeneity of electron beams using transmitted radiation through lead.

PubMed

Pradhan, A S; Quast, U; Sharma, P K

1994-09-01

A simple and fast, but sensitive TLD method for the measurement of energy and homogeneity of therapeutically used electron beams has been developed and tested. This method is based on the fact that when small thicknesses of high-Z absorbers such as lead are interposed in the high-energy electron beams, the transmitted radiation increases with the energy of the electron beams. Consequently, the ratio of readouts of TLDS held on the two sides of a lead plate varied sharply (by factor of 70) with a change in energy of the electron beam from 5 MeV to 18 MeV, offering a very sensitive method for the measurement of the energy of electron beams. By using the ratio of TL readouts of two types of TLD ribbon with widely different sensitivities, LiF TLD-700 ribbons on the upstream side and highly sensitive CaF2:Dy TLD-200 ribbons on the downstream side, an electron energy discrimination of better than +/- 0.1 MeV could be achieved. The homogeneity of the electron beam energy and the absorbed dose was measured by using a jig in which the TLDS were held in the desired array on both sides of a 4 mm thick lead plate. The method takes minimal beam time and makes it possible to carry out measurements for the audit of the quality of electron beams as well as for intercomparison of beams by mail.

Radiological and microwave Protection at NRL, January - December 1983

DTIC Science & Technology

1984-06-27

reduced to background. 18 Surveys with TLD badges were made on pulsed electron beam machines in Buildings 101 and A68 throughout the year. The Gamble...calibration of radiation dosimetry systems required by the Laboratory’s radiological safety program, or by other Laboratory or Navy groups. The Section...provides consultation and assistance on dosimetry problems to the Staff, Laboratory, and Navy. The Section maintains and calibrates fixed-field radiac

The Effect of Badges on the Engagement of Students with Special Educational Needs: A Case Study

ERIC Educational Resources Information Center

Sitra, Ourania; Katsigiannakis, Vangelis; Karagiannidis, Charalampos; Mavropoulou, Sofia

2017-01-01

This paper addresses the perceived benefits from gamification in the context of special education. It presents the findings of a study evaluating the effects of a specific gamification element (badges) on the engagement of five students with special learning needs, through online courses developed on the Moodle Learning Management System (LMS).…

Effective dose assessment in the maxillofacial region using thermoluminescent (TLD) and metal oxide semiconductor field-effect transistor (MOSFET) dosemeters: a comparative study

PubMed Central

Schulze, D; Wolff, J; Rottke, D

2014-01-01

Objectives: The objective of this study was to compare the performance of metal oxide semiconductor field-effect transistor (MOSFET) technology dosemeters with thermoluminescent dosemeters (TLDs) (TLD 100; Thermo Fisher Scientific, Waltham, MA) in the maxillofacial area. Methods: Organ and effective dose measurements were performed using 40 TLD and 20 MOSFET dosemeters that were alternately placed in 20 different locations in 1 anthropomorphic RANDO® head phantom (the Phantom Laboratory, Salem, NY). The phantom was exposed to four different CBCT default maxillofacial protocols using small (4 × 5 cm) to full face (20 × 17 cm) fields of view (FOVs). Results: The TLD effective doses ranged between 7.0 and 158.0 µSv and the MOSFET doses between 6.1 and 175.0 µSv. The MOSFET and TLD effective doses acquired using four different (FOV) protocols were as follows: face maxillofacial (FOV 20 × 17 cm) (MOSFET, 83.4 µSv; TLD, 87.6 µSv; −5%); teeth, upper jaw (FOV, 8.5 × 5.0 cm) (MOSFET, 6.1 µSv; TLD, 7.0 µSv; −14%); tooth, mandible and left molar (FOV, 4 × 5 cm) (MOSFET, 10.3 µSv; TLD, 12.3 µSv; −16%) and teeth, both jaws (FOV, 10 × 10 cm) (MOSFET, 175 µSv; TLD, 158 µSv; +11%). The largest variation in organ and effective dose was recorded in the small FOV protocols. Conclusions: Taking into account the uncertainties of both measurement methods and the results of the statistical analysis, the effective doses acquired using MOSFET dosemeters were found to be in good agreement with those obtained using TLD dosemeters. The MOSFET dosemeters constitute a feasible alternative for TLDs for the effective dose assessment of CBCT devices in the maxillofacial region. PMID:25143020

Effective dose assessment in the maxillofacial region using thermoluminescent (TLD) and metal oxide semiconductor field-effect transistor (MOSFET) dosemeters: a comparative study.

PubMed

Koivisto, J; Schulze, D; Wolff, J; Rottke, D

2014-01-01

The objective of this study was to compare the performance of metal oxide semiconductor field-effect transistor (MOSFET) technology dosemeters with thermoluminescent dosemeters (TLDs) (TLD 100; Thermo Fisher Scientific, Waltham, MA) in the maxillofacial area. Organ and effective dose measurements were performed using 40 TLD and 20 MOSFET dosemeters that were alternately placed in 20 different locations in 1 anthropomorphic RANDO(®) head phantom (the Phantom Laboratory, Salem, NY). The phantom was exposed to four different CBCT default maxillofacial protocols using small (4 × 5 cm) to full face (20 × 17 cm) fields of view (FOVs). The TLD effective doses ranged between 7.0 and 158.0 µSv and the MOSFET doses between 6.1 and 175.0 µSv. The MOSFET and TLD effective doses acquired using four different (FOV) protocols were as follows: face maxillofacial (FOV 20 × 17 cm) (MOSFET, 83.4 µSv; TLD, 87.6 µSv; -5%); teeth, upper jaw (FOV, 8.5 × 5.0 cm) (MOSFET, 6.1 µSv; TLD, 7.0 µSv; -14%); tooth, mandible and left molar (FOV, 4 × 5 cm) (MOSFET, 10.3 µSv; TLD, 12.3 µSv; -16%) and teeth, both jaws (FOV, 10 × 10 cm) (MOSFET, 175 µSv; TLD, 158 µSv; +11%). The largest variation in organ and effective dose was recorded in the small FOV protocols. Taking into account the uncertainties of both measurement methods and the results of the statistical analysis, the effective doses acquired using MOSFET dosemeters were found to be in good agreement with those obtained using TLD dosemeters. The MOSFET dosemeters constitute a feasible alternative for TLDs for the effective dose assessment of CBCT devices in the maxillofacial region.

Lateral vibration behavior analysis and TLD vibration absorption design of the soft yoke single-point mooring system

NASA Astrophysics Data System (ADS)

Lyu, Bai-cheng; Wu, Wen-hua; Yao, Wei-an; Du, Yu

2017-06-01

Mooring system is the key equipment of FPSO safe operation. The soft yoke mooring system is regarded as one of the best shallow water mooring strategies and widely applied to the oil exploitation in the Bohai Bay in China and the Gulf of Mexico. Based on the analysis of numerous monitoring data obtained by the prototype monitoring system of one FPSO in the Bohai Bay, the on-site lateral vibration behaviors found on the site of the soft yoke subject to wave load were analyzed. ADAMS simulation and model experiment were utilized to analyze the soft yoke lateral vibration and it was determined that lateral vibration was resonance behaviors caused by wave excitation. On the basis of the soft yoke longitudinal restoring force being guaranteed, a TLD-based vibration damper system was constructed and the vibration reduction experiments with multi-tank space and multi-load conditions were developed. The experimental results demonstrated that the proposed TLD vibration reduction system can effectively reduce lateral vibration of soft yoke structures.

Variations in photon energy spectra of a 6 MV beam and their impact on TLD response

PubMed Central

Scarboro, Sarah B.; Followill, David S.; Howell, Rebecca M.; Kry, Stephen F.

2011-01-01

Purpose: Measurement of the absorbed dose from radiotherapy beams is an essential component of providing safe and reproducible treatment. For an energy-dependent dosimeter such as thermoluminescent dosimeters (TLDs), it is generally assumed that the energy spectrum is constant throughout the treatment field and is unperturbed by field size, depth, field modulation, or heterogeneities. However, this does not reflect reality and introduces error into clinical dose measurements. The purpose of this study was to evaluate the variability in the energy spectrum of a Varian 6 MV beam and to evaluate the impact of these variations in photon energy spectra on the response of a common energy-dependent dosimeter, TLD. Methods: Using Monte Carlo methods, we calculated variations in the photon energy spectra of a 6 MV beam as a result of variations of treatment parameters, including field size, measurement location, the presence of heterogeneities, and field modulation. The impact of these spectral variations on the response of the TLD is largely based on increased photoelectric effect in the dosimeter, and this impact was calculated using Burlin cavity theory. Measurements of the energy response were also made to determine the additional energy response due to all intrinsic and secondary effects. Results: For most in-field measurements, regardless of treatment parameter, the dosimeter response was not significantly affected by the spectral variations (<1% effect). For measurement points outside of the treatment field, where the spectrum is softer, the TLD over-responded by up to 12% due to an increased probability of photoelectric effect in the TLD material as well as inherent ionization density effects that play a role at low photon energies. Conclusions: It is generally acceptable to ignore the impact of variations in the photon spectrum on the measured dose for locations within the treatment field. However, outside the treatment field, the spectra are much softer, and a

Radiological properties of plastics and TLD materials its application in radiation dosimetry

NASA Astrophysics Data System (ADS)

Jabaseelan Samuel, E. James; Srinivasan, K.; Poopathi, V.

2017-05-01

In the current study, we evaluated the tissue equivalency of nine different commonly used thermoluminescence compounds and six plastic materials over the photon energy range of 15 KeV to 20 MeV. Our result confirmed that the ratio of number of electrons per gram, electron density of the entire TLD compounds and plastic materials to ICRU-44 soft tissue was lesser than unity, except in the case of polypropylene plastics. The effective atomic number ratio of all the plastic materials was also <1 excluding Poly-vinyl-chloride, and for TLD lithium borate material, it was <1 others which showed the deviation with respect to photon energy. Mass attenuation coefficient (µ/ϼ), mass absorption coefficient (µen/ρ) was calculated and the results are discussed in this paper.

An approach to an analysis of the energy response of LiF-TLD to high energy electrons.

PubMed

Shiragai, A

1977-05-01

Responses of LiF-TLD to high energy electrons relative to 60Co gamma-rays were investigated experimentally and theoretically. The Burlin et al. theory, its modified version by Almond and McCray and the Holt et al. semi-empirical theory were examined in comparison with each experiment. An approximate approach to theoretical analysis of energy response of LiF-TLD was attempted and compared with some experimental results.

Evaluation of the Sensitivity and Signal Response of the DT-702 LiF:Mg,Cu,P TLD

DTIC Science & Technology

2007-06-27

energy stored from the radiation interactions that occurs prior to the TLD being read. Electrons can absorb additional energy from sources other...thermoluminescent dosimetry , annealing is the 24 process used to clear any radiation exposure information from a TLD , preparing it for reuse...702 four-chip TLDs were obtained from the Naval Dosimetry Center (NDC), Bethesda, MD. Each card was tested by Thermo prior to delivery to NDC to

Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance

PubMed Central

Liuzzi, Raffaele; Savino, Federica; D’Avino, Vittoria; Pugliese, Mariagabriella; Cella, Laura

2015-01-01

Background Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2–12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters. Methods LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0–10 Gy in step of 2Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy. Results The TLD-100 dose-response curves were obtained. In the dose range of 0–10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05). Conclusions This study demonstrates that the TLD dose response, for doses ≤10Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided. PMID:26427065

Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance.

PubMed

Liuzzi, Raffaele; Savino, Federica; D'Avino, Vittoria; Pugliese, Mariagabriella; Cella, Laura

2015-01-01

Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2-12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters. LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0-10 Gy in step of 2 Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy. The TLD-100 dose-response curves were obtained. In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05). This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided.

A novel personal air sampling device for collecting volatile organic compounds: a comparison to charcoal tubes and diffusive badges.

PubMed

Rossner, Alan; Farant, Jean-Pierre

2004-02-01

Evacuated canisters have been used for many years to collect ambient air samples for gases and vapors. Recently, significant interest has arisen in using evacuated canisters for personal breathing zone sampling as an alternative to sorbent sampling. A novel flow control device was designed and built at McGill University. The flow control device was designed to provide a very low flow rate, <0.5 mL/min, to allow a sample to be collected over an extended period of time. Previous experiments run at McGill have shown agreement between the mathematical and empirical models to predict flow rate. The flow control device combined with an evacuated canister (capillary flow control-canister) was used in a series of experiments to evaluate its performance against charcoal tubes and diffusive badges. Air samples of six volatile organic compounds were simultaneously collected in a chamber using the capillary flow control-canister, charcoal tubes, and diffusive badges. Five different concentrations of the six volatile organic compounds were evaluated. The results from the three sampling devices were compared to each other and to concentration values obtained using an online gas chromatograph (GC). Eighty-four samples of each method were collected for each of the six chemicals. Results indicate that the capillary flow control-canister device compares quite favorably to the online GC and to the charcoal tubes, p > 0.05 for most of the tests. The capillary flow control-canister was found to be more accurate for the compounds evaluated, easier to use, and easier to analyze than charcoal tubes and passive dosimeter badges.

Effects of the Boy Scouts of America Personal Fitness Merit Badge on Cardio-Metabolic Risk, Health Related Fitness and Physical Activity in Adolescent Boys.

PubMed

Maxwell, Justin; Burns, Ryan D; Brusseau, Timothy A

2017-01-01

A growing number of adolescents are more sedentary and have fewer formal opportunities to participate in physical activity. With the mounting evidence that sedentary time has a negative impact on cardiometabolic profiles, health related fitness and physical activity, there is a pressing need to find an affordable adolescent physical activity intervention. One possible intervention that has been overlooked in the past is Boy Scouts of America. There are nearly 900,000 adolescent boys who participate in Boy Scouts in the United States. The purpose of this research study was to evaluate the effect of the Personal Fitness merit badge system on physical activity, health-related fitness, and cardio-metabolic blood profiles in Boy Scouts 11-17 years of age. Participants were fourteen (N = 14) Boy Scouts from the Great Salt Lake Council of the Boy Scouts of America who earned their Personal Fitness merit badge. Classes were held in the Spring of 2016 where boys received the information needed to obtain the merit badge and data were collected. Results from the related-samples Wilcoxon signed rank test showed that the median of differences between VO 2 peak pre-test and post-test scores were statistically significant ( p = 0.004). However, it also showed that the differences between the Pre-MetS (metabolic syndrome) and Post-MetS scores (p = 0.917), average steps taken per day ( p = 0.317), and BMI ( p = 0.419) were not statistically significant. In conclusion, the merit badge program had a positive impact on cardiovascular endurance, suggesting this program has potential to improve cardiovascular fitness and should be considered for boys participating in Boy Scouts.

Comparison of doses calculated by the Monte Carlo method and measured by LiF TLD in the buildup region for a 60Co photon beam.

PubMed

Budanec, M; Knezević, Z; Bokulić, T; Mrcela, I; Vrtar, M; Vekić, B; Kusić, Z

2008-12-01

This work studied the percent depth doses of (60)Co photon beams in the buildup region of a plastic phantom by LiF TLD measurements and by Monte Carlo calculations. An agreement within +/-1.5% was found between PDDs measured by TLD and calculated by the Monte Carlo method with the TLD in a plastic phantom. The dose in the plastic phantom was scored in voxels, with thickness scaled by physical and electron density. PDDs calculated by electron density scaling showed a better match with PDD(TLD)(MC); the difference is within +/-1.5% in the buildup region for square and rectangular field sizes.

Analysis of read-out heating rate effects on the glow peaks of TLD-100 using WinGCF software

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

Bauk, Sabar, E-mail: sabar@usm.my; Hussin, Siti Fatimah; Alam, Md. Shah

This study was done to analyze the effects of the read-out heating rate on the LiF:Mg,Ti (TLD-100) thermoluminescent dosimeters (TLD) glow peaks using WinGCF computer software. The TLDs were exposed to X-ray photons with a potential difference of 72 kVp and 200 mAs in air and were read-out using a Harshaw 3500 TLD reader. The TLDs were read-out using four read-out heating rates at 10, 7, 4 and 1 °C s{sup −1}. It was observed that lowering the heating rate could separate more glow peaks. The activation energy for peak 5 was found to be lower than that for peakmore » 4. The peak maximum temperature and the integral value of the main peak decreased as the heating rate decreases.« less

[The application of non-annealing thermoluminescent dosimetry (TLD)].

PubMed

Wu, J M; Chen, C S; Lan, R H

1993-06-01

Conventional use of Thermoluminescence (TL) in radiation dosimetry is very time-consuming. It requires repeating the procedures of preheating and annealing. In an attempt to simplify these procedures, we conducted an experiment of non-annealing TL dosimetry. This article reports the experiment's results. We adopted Lithium Fluoride (LiF) chip (TLD-100) in polystyrene under the exposure of Co-60, and the result was taken by HAR-SHAW-4000 TL reading system. The TL response was analyzed, including linearity, reproducibility and fading test. Because non-annealing TL response was greatly influenced by residual electron, TLD calibration curves were separated into two parts: (1) high dose region (HDR, 50-1500 cGy); (2) low dose region (LDR, 0-50 cGy). When TL dosimeters were exposed to a single high does (about 500 cGy), the HDR could be reproduced within 3% and fit a good linearity. For LDR, we had to give up the tail of glow curve in the high temperature region. We could then get good linearity and reproducibility. Furthermore, fading of non-annealing was apparently larger than annealing. We could control the fading of non-annealing was apparently larger than annealing. We could control the fading influence within 1% by taking the TL reading one hour after exposure. On the other hand, a combination of photon and electron exposure was also performed by non-annealing TL dosimetry. The results were compatible with Co-60 exposure in the same system.

Creating a Novel Online Digital Badge-Awarding Program in Patient Navigation to Address Healthcare Access.

PubMed

Rohan, Annie J; Fullerton, Judith; Escallier, Lori A; Pati, Susmita

A novel, sustainable digital badge-awarding online course was developed to prepare learners with familiarity of patient navigation. Learners offered favorable endorsement of essentially all elements of the program, especially the utility of the Blackboard learning management software program. Quality Matters standards provided a rigorous framework for the challenges of designing, implementing, and evaluating online curricula. Online education is an effective method for meeting the professional development needs of those seeking careers in care coordination/patient navigation.

Out-of-field in vivo dosimetry using TLD in SABR for primary kidney cancer involving mixed photon fields.

PubMed

Lonski, P; Keehan, S; Siva, S; Pham, D; Franich, R D; Taylor, M L; Kron, T

2017-05-01

To assess out-of-field dose using three different variants of LiF thermoluminescence dosimeters (TLD) for ten patients who underwent stereotactic ablative body radiotherapy (SABR) for primary renal cell carcinoma (RCC) and compare with treatment planning system (TPS) dose calculations. Thermoluminescent dosimeter (TLD) measurements were conducted at 20, 30, 40 and 50cm from isocentre on ten patients undergoing SABR for primary RCC. Three types of high-sensitivity LiF:Mg,Cu,P TLD material with different 6 Li/ 7 Li isotope ratios were used. Patient plans were calculated using Eclipse Anisotropic Analytical Algorithm (AAA) for clinical evaluation and recalculated using Pencil Beam Convolution (PBC) algorithm for comparison. Both AAA and PBC showed diminished accuracy for photon doses at increasing distance out-of-field. At 50cm, measured photon dose was 0.3cGy normalised to a 10Gy prescription on average with only small variation across all patients. This is likely due to the leakage component of the out-of-field dose. The 6 Li-enriched TLD materials showed increased signal attributable to additional neutron contribution. LiF:Mg,Cu,P TLD containing 6 Li is sensitive enough to measure out-of-field dose 50cm from isocentre however will over-estimate the photon component of out-of-field dose in high energy treatments due to the presence of thermal neutrons. 7 Li enriched materials which are insensitive to neutrons are therefore required for accurate photon dosimetry. Neutron signal has been shown here to increase with MUs and is higher for patients treated using certain non coplanar beam arrangements. Further work is required to convert this additional neutron signal to dose. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A U.S. Multicenter Study of Recorded Occupational Radiation Badge Doses in Nuclear Medicine.

PubMed

Villoing, Daphnée; Yoder, R Craig; Passmore, Christopher; Bernier, Marie-Odile; Kitahara, Cari M

2018-05-01

Purpose To summarize occupational badge doses recorded for a sample of U.S. nuclear medicine technologists. Materials and Methods Nine large U.S. medical institutions identified 208 former and current nuclear medicine technologists certified after 1979 and linked these individuals to historic badge dose records maintained by a commercial dosimetry company (Landauer), yielding a total of 2618 annual dose records. The distributions of annual and cumulative occupational doses were described by using summary statistics. Results Between 1992 and 2015, the median annual personal dose equivalent per nuclear medicine technologist was 2.18 mSv (interquartile range [IQR], 1.25-3.47 mSv; mean, 2.69 mSv). Median annual personal dose equivalents remained relatively constant over this period (range, 1.40-3.30 mSv), while maximum values generally increased over time (from 8.00 mSv in 1992 to 13.9 mSv in 2015). The median cumulative personal dose equivalent was 32.9 mSv (IQR, 18.1-65.5 mSv; mean, 51.4 mSv) for 45 technologists who had complete information and remained employed through 2015. Conclusion Occupational radiation doses were well below the established occupational limits and were consistent with those observed for nuclear medicine technologists worldwide and were greater than those observed for nuclear and general medical workers in the United States These results should be informative for radiation monitoring and safety efforts in nuclear medicine departments. © RSNA, 2018 Online supplemental material is available for this article.

SU-E-T-108: Development of a Novel Clinical Neutron Dose Monitor for Proton Therapy Based On Twin TLD500 Chips in a Small PE Moderator

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

Hentschel, R; Mukherjee, B

2014-06-01

Purpose: In proton therapy, it could be desirable to measure out-of-field fast neutron doses at critical locations near and outside the patient body. Methods: The working principle of a novel clinical neutron dose monitor is verified by MCNPX simulation. The device is based on a small PE moderator of just 5.5cm side length for easy handling covered with a thermal neutron suppression layer. In the simulation, a polystyrene phantom is bombarded with a standard proton beam. The secondary thermal neutron flux produced inside the moderator by the impinging fast neutrons from the treatment volume is estimated by pairs of α-Al2O3:Cmore » (TLD500) chips which are evaluated offline after the treatment either by TL or OSL methods. The first chip is wrapped with 0.5mm natural Gadolinium foil converting the thermal neutrons to gammas via (n,γ) reaction. The second chip is wrapped with a dummy material. The chip centers have a distance of 2cm from each other. Results: The simulation shows that the difference of gamma doses in the TLD500 chips is correlated to the mean fast neutron dose delivered to the moderator material. Different outer shielding materials have been studied. 0.5mm Cadmium shielding is preferred for cost reasons and convenience. Replacement of PE moderator material by other materials like lead or iron at any place is unfavorable. The spatial orientation of the moderator cube is uncritical. Using variance reduction techniques like splitting/Russian roulette, the TLD500 gamma dose simulation give positive differences up to distances of 0.5m from the treatment volume. Conclusion: Applicability and basic layout of a novel clinical neutron dose monitor are demonstrated. The monitor measures PE neutron doses at locations outside the patient body up to distances of 0.5m from the treatment volume. Tissue neutron doses may be calculated using neutron kerma factors.« less

Comparison of personnel radiation dosimetry from myocardial perfusion scintigraphy: Technetium-99m-sestamibi versus thallium-201

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

Culver, C.M.; Dworkin, H.J.

1993-07-01

The whole-body and hand radiation doses to our technical staff were retrospectively compared for three distinct 4-mo periods when either 201TI or 99mTc-sestamibi were exclusively used for stress myocardial perfusion imaging. During the initial 4-mo period when 99mTc-sestamibi replaced 201TI, the mean whole-body film badge readings increased from 100 to 450 microSv/mo (p < 0.001) for nuclear medicine technologists (n = 10) and from 240 to 560 microSv/mo (p < 0.05) for radiopharmacy technologists (n = 2). Mean TLD readings to the hands also increased, although the differences were not statistically significant for the nuclear medicine technologists. Noninvasive cardiology staffmore » were monitored with film badges and the mean whole-body film badge reading, when 99mTc-sestamibi was the imaging agent, was 360 microSv per month. Radiation reduction methods that decreased radiation exposure to staff were utilized. The most effective included the use of a lead face shield and lead lined storage container in the noninvasive imaging area, handling spills by shielding instead of decontamination and methods to reduce time spent in close proximity to the patient.« less

Overall migration and specific migration of bisphenol A diglycidyl ether monomer and m-xylylenediamine hardener from an optimized epoxy-amine formulation into water-based food simulants.

PubMed

Simal Gándara, J; López Mahía, P; Paseiro Losada, P; Simal Lozano, J; Paz Abuín, S

1993-01-01

The overall and specific migrations of BADGE n = 0 monomer and m-XDA hardener from a BEPOX LAB 889 (Gairesa internal code), epoxy system cured at room temperature, into three water-based food simulants are studied. Hydrolysis of BADGE n = 0 was observed in all of these simulants, giving more polar products. We thus propose changing the EEC Directives, which at present only legislate for levels of BADGE n = 0 monomer in the simulants, to include the hydrolysis products of BADGE monomers. Another alternative would be to express all the migration levels due to BADGE and its derived products in terms of BADGE itself.

TU-F-BRE-07: In Vivo Neutron Detection in Patients Undergoing Stereotactic Ablative Radiotherapy (SABR) for Primary Kidney Cancer Using 6Li and 7Li Enriched TLD Pairs

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

Lonski, P; Kron, T; RMIT University, Melbourne, Victoria

Purpose: Stereotactic ablative radiotherapy (SABR) for primary kidney cancer often involves the use of high-energy photons combined with a large number of monitor units. While important for risk assessment, the additional neutron dose to untargeted healthy tissue is not accounted for in treatment planning. This work aims to detect out-of-field neutrons in vivo for patients undergoing SABR with high-energy (>10 MV) photons and provides preliminary estimates of neutron effective dose. Methods: 3 variations of high-sensitivity LiF:Mg,Cu,P thermoluminescent dosimeter (TLD) material, each with varying {sup 6}Li / {sup 7}Li concentrations, were used in custom-made Perspex holders for in vivo measurements. Themore » variation in cross section for thermal neutrons between Li isotopes was exploited to distinguish neutron from photon signal. Measurements were made out-of-field for 7 patients, each undergoing 3D-conformal SABR treatment for primary kidney cancer on a Varian 21iX linear accelerator. Results: In vivo measurements show increased signal for the {sup 6}Li enriched material for patients treated with 18 MV photons. Measurements on one SABR patient treated using only 6 MV showed no difference between the 3 TLD materials. The out-of-field photon signal decreased exponentially with distance from the treatment field. The neutron signal, taken as the difference between {sup 6}Li enriched and {sup 7}Li enriched TLD response, remains almost constant up to 50 cm from the beam central axis. Estimates of neutron effective dose from preliminary TLD calibration suggest between 10 and 30 mSv per 1000 MU delivered at 18 MV for the 7 patients. Conclusion: TLD was proven to be a useful tool for the purpose of in vivo neutron detection at out-of-field locations. Further work is required to understand the relationship between TL signal and neutron dose. Dose estimates based on preliminary TLD calibration in a neutron beam suggest the additional neutron dose was <30 mSv per 1000 MU

Improved sample extraction and clean-up for the GC-MS determination of BADGE and BFDGE in vegetable oil.

PubMed

Brede, C; Skjevrak, I; Herikstad, H; Anensen, E; Austvoll, R; Hemmingsen, T

2002-05-01

A straightforward method was established for the determination of migration contaminants in olive oil with a special focus on the two can-coating migration compounds bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE). The preferred sample preparation was a single liquid-liquid extraction of compounds from the oil into 20% (v/v) methanol in acetonitrile, followed by clean-up with solid-phase extraction on aminopropyl bonded to silica. This purification procedure selectively removed all free fatty acids from the extracts without removing phenolic compounds of interest. The solid-phase extraction columns were used many times by implementing a procedure of washing out the strongly retained fatty acids with 2% acetic acid in methanol. Gas chromatography coupled with full scan (m/z 33-700) electron ionization mass spectrometry was used for the determination of several model compounds in olive oil samples. BADGE and BFDGE could be determined in the 0.05-2 mg kg(-1) range in oil samples with a relative SD of <6% (six replicates). The method was used in an enforcement campaign for the Norwegian Food Control Authority to analyse vegetable oil samples from canned fish-in-oil.

External audits of electron beams using mailed TLD dosimetry: preliminary results.

PubMed

Gomola, I; Van Dam, J; Isern-Verdum, J; Verstraete, J; Reymen, R; Dutreix, A; Davis, B; Huyskens, D

2001-02-01

A feasibility study has been performed to investigate the possibility of using mailed thermoluminescence dosimetry (TLD) for external audits of clinical electron beams in Europe. In the frame of the EC Network Project for Quality Assurance in Radiotherapy, instruction sheets and mailing procedures have been defined for mailed TLD dosimetry using the dedicated holder developed by a panel of experts of the International Atomic Energy Agency (IAEA). Three hundred and thirty electron beam set-ups have been checked in the reference centres and some local centres of the EC Network Project and in addition through the centres participating to the EORTC Radiotherapy Group trial 22922. The mean ratio of measured dose to stated dose is 0.2% and the standard deviation of measured dose to stated dose is 3.2%. In seven beam set-ups, deviations greater than 10% were observed (max. 66%), showing the usefulness of these checks. The results of this feasibility study (instruction sheets, mailing procedures, holder) are presently endorsed by the EQUAL-ESTRO structure in order to offer in the future to all ESTRO members the possibility to request external audits of clinical electron beams.

The Development of a Beta-Gamma Personnel Dosimeter

NASA Astrophysics Data System (ADS)

Tsakeres, Frank Steven

The assessment of absorbed dose in mixed beta and gamma radiation fields is an extremely complex task. For many years, the assessment of the absorbed dose to tissue from the weakly penetrating components of a radiation field (i.e., beta particles, electrons) has been largely ignored. Beta radiation fields are encountered routinely in a nuclear facility and may represent the major radiation component under certain accident or emergency conditions. Many attempts have been made to develop an accurate mixed field personnel dosimeter. However, all of these dosimeters have exhibited numerous response problems which have limited their usefulness for personnel dose assessment. Consequently, the determination of the absorbed dose at the epidermal depth (i.e., 7 mg/cm('2)) has been difficult to measure accurately. The objective of this research project was to design, build, and test a sensitive and accurate personnel dosimeter for mixed field applications. The selection of the various dosimeter elements were determined by evaluating several types of phosphors, filters, and backscatter materials. After evaluating the various response characteristics of the badge components, a prototype dosimeter, the CHEMM (CaF(,2):Dy Highly Efficient Multiple Element Multiple Filter) personnel dosimeter, was developed and tested at Georgia Tech, Emory University and the National Bureau of Standards. This dosimeter was comprised of four large CaF(,2):Dy (TLD-200) TLD's and a standard LiF (TLD-100) chip. The weakly penetrating and penetrating components of a radiation field were separated using a series of TLD/filter combinations and a new dose assessment algorithm. The large TLD-200 chips, along with a series of tissue-equivalent filters, were used to determine the absorbed dose due to the weakly penetrating radiation while a LiF/filter combination was used to measure the penetrating component. In addition, a new backscatter material was included in the badge design to better simulate a

Effect of heating rate on thermoluminescence output of LiF: Mg, Ti (TLD-100) in dosimetric applications

NASA Astrophysics Data System (ADS)

Singh, Ranjit; Kainth, Harpreet Singh

2018-07-01

The luminiscence characteristics of thermoluminscence dosimeter LiF: Mg, Ti (TLD-100) irradiated to X-rays from 6 MV linac have been studied for wide range of 2-50 K/s readout linear heating rates. The reproducibility of glow curves for TLDs is found to be better at lower heating rates and depreciate at higher heating rates. The glow curve spectra were analysed using deconvolution procedure based on general-order kinetics. Shift in the peak maximum temperature per unit rise in heating rate for various peaks were found to decrease with heating rate. The TLDs irradiated with same dose exhibit decreasing TL counts with increase in the heating rate, which indicate the thermal quenching effect in TLD-100. The value of activation energy for each peak within the glow curve increases with heating rate. Calibration curves plotted for the dose range 0.4-1020 cGy exhibit decreasing slope with increasing readout heating rate. Corrections for temperature lag between the heating element and the dosimeter, and the effective heating rate (βeff) across the sample estimated using formulation proposed by Kitis and Tuyn and are found to be fairly applicable.

A combined TLD/emulsion method of sampling dosimetry applied to Apollo missions

NASA Technical Reports Server (NTRS)

Schaefer, H. J.

1979-01-01

A system which simplifies the complex monitoring methods used to measure the astronaut's radiation exposure in space is proposed. The excess dose equivalents of trapped protons and secondary neutrons, protons, and alpha particles from local nuclear interactions are determined and a combined thermoluminescent dosimeter (TLD)/nuclear emulsion method which measures the absorbed dose with thermoluminescent dosimeter chips is presented.

SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

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

Chen, Y; Lin, Y; Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan

Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ({sup 6}LiF: Mg, Ti) and TLD-700 ({sup 7}LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure ismore » 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)« less

Use of mobile and passive badge air monitoring data for NOX and ozone air pollution spatial exposure prediction models.

PubMed

Xu, Wei; Riley, Erin A; Austin, Elena; Sasakura, Miyoko; Schaal, Lanae; Gould, Timothy R; Hartin, Kris; Simpson, Christopher D; Sampson, Paul D; Yost, Michael G; Larson, Timothy V; Xiu, Guangli; Vedal, Sverre

2017-03-01

Air pollution exposure prediction models can make use of many types of air monitoring data. Fixed location passive samples typically measure concentrations averaged over several days to weeks. Mobile monitoring data can generate near continuous concentration measurements. It is not known whether mobile monitoring data are suitable for generating well-performing exposure prediction models or how they compare with other types of monitoring data in generating exposure models. Measurements from fixed site passive samplers and mobile monitoring platform were made over a 2-week period in Baltimore in the summer and winter months in 2012. Performance of exposure prediction models for long-term nitrogen oxides (NO X ) and ozone (O 3 ) concentrations were compared using a state-of-the-art approach for model development based on land use regression (LUR) and geostatistical smoothing. Model performance was evaluated using leave-one-out cross-validation (LOOCV). Models performed well using the mobile peak traffic monitoring data for both NO X and O 3 , with LOOCV R 2 s of 0.70 and 0.71, respectively, in the summer, and 0.90 and 0.58, respectively, in the winter. Models using 2-week passive samples for NO X had LOOCV R 2 s of 0.60 and 0.65 in the summer and winter months, respectively. The passive badge sampling data were not adequate for developing models for O 3 . Mobile air monitoring data can be used to successfully build well-performing LUR exposure prediction models for NO X and O 3 and are a better source of data for these models than 2-week passive badge data.

Comparing Digital Badges-and-Points with Classroom Token Systems: Effects on Elementary School ESL Students' Classroom Behavior and English Learning

ERIC Educational Resources Information Center

Homer, Ryan; Hew, Khe Foon; Tan, Cheng Yong

2018-01-01

This paper reports the findings of a field experiment that gamified the classroom experience of elementary school ESL students by implementing digital badges-and-points which students could earn by achieving specific behavioral and learning goals. Altogether, 120 children in eight different classes participated in this study. Four of the classes…

Dosimetric evaluation of the staff working in a PET/CT department

NASA Astrophysics Data System (ADS)

Dalianis, K.; Malamitsi, J.; Gogou, L.; Pagou, M.; Efthimiadou, R.; Andreou, J.; Louizï, A.; Georgiou, E.

2006-12-01

The dosimetric literature data concerning the medical personnel working in positron emission tomography/computed tomography (PET/CT) departments are limited. Therefore, we measured the radiation dose of the staff working in the first PET/CT department in Greece at the Diagnostic and Therapeutic Center of Athens HYGEIA—Harvard Medical International. As, for the time being, only 2-deoxy-2-[ 18F]fluoro-d-glucose (FDG) PET studies are performed, radiation dose measurements concern those derived from dispensing of the radiopharmaceutical as well as from the patients undergoing FDG-PET imaging. Our aim is to develop more effective protective measures against radionuclide exposure. To estimate the effective dose from external exposure, all seven members of the staff (two nurses, two medical physicists, two technologists, one secretary) had TLD badges worn at the upper pocket of their overall, TLD rings on the right hand and digital dosimeters at their upper side pocket. In addition, isodose curves were measured with thermoluminescence detectors for distances of 20, 50, 70 and 100 cm away from patients who had been injected with 18F-FDG. Dose values of the PET/CT staff were measured with digital detectors, TLD badges and TLD rings over the first 8 months for a total of 160 working days of the department's operation, consisting of a workload of about 10-15 patients/week who received 250-420 MBq of 18F-FDG each. Whole - body collective doses and hand doses for the staff were the following: Nurse #1 received 1.6 mSv as a whole body dose and 2,1 as a hand dose, Nurse #2 received 1.9 and 2.4 mSv respectively. For medical physicist #1 the dose values were 1.45 mSv whole body and 1.7 mSv hand dose, for medical physicist #2 1.67 mSv wholebody dose and 1.55 mSv hand dose and for technologists #1 & #2 the whole body doses were 0.7 and 0.64 mSv respectively. Lastly, the secretary received 0.1 mSv whole body dose. These preliminary data have shown that the dose levels of our PET

Determination of BPA, BPB, BPF, BADGE and BFDGE in canned energy drinks by molecularly imprinted polymer cleaning up and UPLC with fluorescence detection.

PubMed

Gallo, Pasquale; Di Marco Pisciottano, Ilaria; Esposito, Francesco; Fasano, Evelina; Scognamiglio, Gelsomina; Mita, Gustavo Damiano; Cirillo, Teresa

2017-04-01

A new method for simultaneous determination of five bisphenols in canned energy drinks by UPLC with fluorescence detection, after clean up on molecularly imprinted polymers, is herein described. The method was validated at two concentration levels, calculating trueness, repeatability and within-laboratory reproducibility, specificity, linearity of detector response, the limits of quantifications and the limits of detection for each bisphenol. The method is specific, reliable and very sensitive, allowing for determination of bisphenol F diglycidyl ether (BFDGE), bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF) and bisphenol A diglycidyl ether (BADGE) down to 0.50ng/mL; it was employed to determine contamination levels from these bisphenols in forty energy drinks of different brands, collected from the market in Naples. BPA was detected in 17 out of 40 samples (42.5%); in some energy drinks also BPF, BADGE and BFDGE were determined. Copyright © 2016 Elsevier Ltd. All rights reserved.

SU-F-19A-06: Experimental Investigation of the Energy Dependence of TLD Sensitivity in Low-Energy Photon Beams

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

Chen, Z; Nath, R

Purpose: To measure the energy dependence of TLD sensitivity in lowenergy photon beams with equivalent mono-energetic energy matching those of 103Pd, 125I and 131Cs brachytherapy sources. Methods: A Pantek DXT 300 x-ray unit (Precision X-ray, Branford, CT), with stable digital voltage control down to 20 kV, was used to establish three lowenergy photon beams with narrow energy spread and equivalent monoenergetic energies matching those of 103Pd, 125I and 131Cs brachytherapy sources. The low-energy x-ray beams and a reference 6 MV photon beam were calibrated according to the AAPM TG-61 and TG-51 protocols, respectively, using a parallel-plate low-energy chamber and amore » Farmer cylindrical chamber with NIST traceable calibration factors. The dose response of model TLD-100 micro-cubes (1×1×1 mm{sup 3}) in each beam was measured for five different batches of TLDs (each contained approximately 100 TLDs) that have different histories of irradiation and usage. Relative absorbed dose sensitivity was determined as the quotient of the slope of dose response for a beam-of-interest to that of the reference beam. Results: Equivalent mono-energetic photon energies of the low-energy beams established for 103Pd, 125I and 131Cs sources were 20.5, 27.5, and 30.1 keV, respectively. Each beam exhibited narrow spectral spread with energyhomogeneity index close to 90%. The relative absorbed-dose sensitivity was found to vary between different batches of TLD with maximum differences of up to 8%. The mean and standard deviation determined from the five TLD batches was 1.453 ± 0.026, 1.541 ± 0.035 and 1.529 ± 0.051 for the simulated 103P, 125I and 131Cs beams, respectively. Conclusion: Our measured relative absorbed-dose sensitivities are greater than the historically measured value of 1.41. We find that the relative absorbed-dose sensitivity of TLD in the 103P beam is approximately 5% lower than that of 125I and 131Cs beams. Comparison of our results with other studies will be

SU-E-J-101: Retroactive Calculation of TLD and Film Dose in Anthropomorphic Phantom as Assessment of Updated TPS Performance

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

Alkhatib, H; Oves, S

Purpose: To demonstrate a quick and comprehensive method verifying the accuracy of the updated dose model by recalculating dose distribution in an anthropomorphic phantom with a new version of the TPS and comparing the results to measured values. Methods: CT images and IMRT plan of an RPC anthropomorphic head phantom, previously calculated by Pinnacle 9.0, was re-computed using Pinnacle 9.2 and 9.6. The dosimeters within the phantom include four TLD capsules representing a primary PTV, two TLD capsules representing a secondary PTV, and two TLD capsules representing an organ at risk. Also included were three sheets of Gafchromic film. Performancemore » of the updated TPS version was assessed by recalculating point doses and dose profiles corresponding to TLD and film position respectively and then comparing the results to reported values by the RPC. Results: Comparing calculated doses to reported measured doses from the RPC yielded an average disagreement of 1.48%, 2.04% and 2.10% for versions 9.0, 9.2, 9.6 respectively. Computed doses points all meet the RPC's passing criteria with the exception of the point representing the superior organ at risk in version 9.6. However, qualitative analysis of the recalculated dose profiles showed improved agreement with those of the RPC, especially in the penumbra region. Conclusion: This work has demonstrated the calculation results of Pinnacle 9.2 and 9.6 vs 9.0 version. Additionally, this study illustrates a method for the user to gain confidence upgrade to a newer version of the treatment planning system.« less

A comparative evaluation of luminescence detectors: RPL-GD-301, TLD-100 and OSL-AL2O3:C, using Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Benali, A.-H.; Medkour Ishak-Boushaki, G.; Nourreddine, A.-M.; Allab, M.; Papadimitroulas, P.

2017-07-01

The luminescent dosimeters are widely used in clinical practice, for the monitoring of patient dose in external radiation therapy. Three of the most common dosimeter categories are the thermoluminescence (TLDs), the radiophotoluminescence (RPLs) and the optically stimulated luminescence (OSLs), with similar physical processes on their properties. The aim of the present study is to compare and evaluate the dosimetric properties of three specific luminescent detectors namely: a) RPL glass dosimeter, commercially known as GD-301, b) lithium fluoride TLD-100 (LiF:Mg,Ti) and c) carbon-doped aluminum oxide (Al2O3:C). For this purpose, Monte Carlo simulations were applied, using the MCNP5 code to estimate the responses of these dosimeters in terms of absorbed dose, output factor, the angular and energy dependence. In the present study, we found that the differences between the output factors were less than ± 4.2% for all detector materials RPLGD, TLD and OSLD. The variations in sensitivity for angles up to ± 80 degrees from the central axis of the beam were approximately 0.5%, 0.8% and 1.5% for the TLD-100, GD-301 and Al2O3:C, respectively. The energy dependence of the RPL and OSL dosimeters are stated as less than a 2.2%, and within 5.8% for TLD.

"5 A Day" achievement badge for urban boy scouts: formative evaluation results.

PubMed

Cullen, K W; Baranowski, T; Baranowski, J; Warnecke, C; de Moor, C; Nwachokor, A; Hajek, R A; Jones, L A

1998-01-01

Certain cancers are more common among African Americans (AA). Fruit and vegetables (F&V) reduce cancer risk, but Americans, and African Americans in particular, do not meet the "5 A Day" goal. Scouting organizations, particularly urban Boy Scout groups that target inner-city youth, provide promising channels for nutritional behavioral change programs. Focus groups were conducted with urban Boy Scouts and their parents to identify factors influencing F&V consumption and evaluate potential intervention activities. Twenty-four-hour dietary recalls were collected from 85 area Boy Scouts. A national data set was used to obtain values for F&V consumption by African American and European American (boys age 0-16). Vegetable preferences were low and a negative peer influence for vegetables was reported. The group has limited food-preparation skills, but both parents and scouts reported that F&V were available in their homes. Use of goal setting and use of problem-solving techniques were limited. The local scouts' mean F&V intake was 3.2 servings per day. Ethnic differences in F&V consumption were identified in the national data. Based on these results and previous interventions in schools, an overall structure for the intervention was developed to include eight weekly troop sessions and two camping sessions, parent newsletters, seven weekly home badge assignments, and ten comic books.

Development of a personal dosimetry system based on optically stimulated luminescence of alpha-Al2O3:C for mixed radiation fields.

PubMed

Lee, S Y; Lee, K J

2001-04-01

To develop a personal optically stimulated luminescence (OSL) dosimetry system for mixed radiation fields using alpha-Al2O3:C, a discriminating badge filter system was designed by taking advantage of its optically stimulable properties and energy dependencies. This was done by designing a multi-element badge system for powder layered alpha-Al2O3:C material and an optical reader system based on high-intensity blue light-emitting diode (LED). The design of the multielement OSL dosimeter badge system developed allows the measurement of a personal dose equivalent value Hp(d) in mixed radiation fields of beta and gamma. Dosimetric properties of the personal OSL dosimeter badge system investigated here were the dose response, energy response and multi-readability. Based on the computational simulations and experiments of the proposed dosimeter design, it was demonstrated that a multi-element dosimeter system with an OSL technology based on alpha-Al2O3:C is suitable to obtain personal dose equivalent information in mixed radiation fields.

The 1998 Australian external beam radiotherapy survey and IAEA/WHO TLD postal dose quality audit.

PubMed

Huntley, R; Izewska, J

2000-03-01

The results of an updated Australian survey of external beam radiotherapy centres are presented. Most of the centres provided most of the requested information. The relative caseloads of various linear accelerator photon and electron beams have not changed significantly since the previous survey in 1995. The mean age of Australian LINACs is 7.1 years and that of other radiotherapy machines is 14.7 years. Every Australian radiotherapy centre participated in a special run of the IAEA/WHO TLD postal dose quality audit program, which was provided for Australian centres by the IAEA and WHO in May 1998. The dose quoted by the centres was in nearly every case within 1.5% of the dose assessed by the IAEA. This is within the combined standard uncertainty of the IAEA TLD service (1.8%). The results confirm the accuracy and precision of radiotherapy dosimetry in Australia and the adequate dissemination of the Australian standards from ARL (now ARPANSA) to the centres. The Australian standards have recently been shown to agree with those of other countries to within 0.25% by comparison with the BIPM.

Beta- and gamma-dose measurements of the Godiva IV critical assembly.

PubMed

Hankins, D E

1984-03-01

To aid in the re-evaluation of an exposure that occurred in 1963, information was required on the response of film badges to the beta- and gamma-ray doses from a critical assembly. Of particular interest was the beta spectra from the assembly. The techniques used and the results obtained in this study are of interest to health physicists at facilities where exposures to betas occur. The dose rates from the Los Alamos National Laboratory Godiva IV Critical Assembly were measured at numerous distances from the assembly four and 12 days following a burst. Information was obtained on the beta-particle spectra using absorption curve studies. The beta/gamma dose-rate ratio as a function of distance from the assembly was determined. Shielding provided by various metals, gloves and clothing was measured. The beta- and gamma-ray doses measured were compared with a film packet used in the past at the Nevada Test Site with two types of current TLD personnel badges. Measurements made with a commercial thin-window ion chamber instrument are compared with the dose rates obtained using other dosimeters.

Thermoluminescent response of LiF (TLD-100) to 5-30 keV electrons and the effect of annealing in various atmospheres.

PubMed

Lasky, J B; Moran, P R

1977-09-01

The response of single crystal and extruded ribbons of TLD-100 to 5-30 keV electrons was investigated. If annealing is done in a vacuum, the sensitivity of TLD-100 single crystals to these electrons and the resultant glow curve are essentially the same as when irradiation are carried out with 137Cs gamma rays. All discrepancies in sensitivity can then be accounted for by the higher LET of electrons. The commonly used 'standard annealing' at 400 degrees C for one hour produced a change in the glow curve shape and a loss in sensitivity in contrast to the vacuum anneal results. Diffusion of hydroxyl ions into the sample during air annealing is believed to be the primary cause for this change. These results explain the source of the 'dead layer' proposed to explain the variation with particle size of the luminescent efficiency of X-ray irradiated TLD-100 powder and the low TL efficiency from low energy electron irradiations. With the use of the vacuum annealing procedure, the same sensitivity and reproducibility can be achieved for the dosimetry of low energy electrons and other shallowly penetrating radiation as is currently achieved for the dosimetry of X-rays.

Design and feasibility of a multi-detector neutron spectrometer for radiation protection applications based on thermoluminescent 6LiF:Ti,Mg (TLD-600) detectors

NASA Astrophysics Data System (ADS)

Lis, M.; Gómez-Ros, J. M.; Bedogni, R.; Delgado, A.

2008-01-01

The design of a neutron detector with spectrometric capability based on thermoluminescent (TL) 6LiF:Ti,Mg (TLD-600) dosimeters located along three perpendicular axis within a single polyethylene (PE) sphere has been analyzed. The neutron response functions have been calculated in the energy range from 10 -8 to 100 MeV with the Monte Carlo (MC) code MCNPX 2.5 and their shape and behaviour have been used to discuss a suitable configuration for an actual instrument. The feasibility of such a device has been preliminary evaluated by the simulation of exposure to 241Am-Be, bare 252Cf and Fe-PE moderated 252Cf sources. The expected accuracy in the evaluation of energy quantities has been evaluated using the unfolding code FRUIT. The obtained results together with additional calculations performed using MAXED and GRAVEL codes show the spectrometric capability of the proposed design for radiation protection applications, especially in the range 1 keV-20 MeV.

Beta ray spectroscopy based on a plastic scintillation detector/silicon surface barrier detector coincidence telescope

NASA Astrophysics Data System (ADS)

Horowitz, Y. S.; Hirning, C. R.; Yuen, P.; Aikens, M.

1994-01-01

Beta radiation is now recognized as a significant radiation safety problem and several international conferences have recently been devoted to the problems of mixed field beta/photon dosimetry. Conventional dosimetry applies algorithms to thermoluminescence dosimetry (TLD) multi-element badges which attempt to extract dose information based on the comparison of TL signals from ``thick/thin'' and/or ``bare/filtered'' elements. These may be grossly innacurate due to inadequate or non-existant knowledge of the energy spectrum of both the beta radiation and the accompanying photon field, as well as other factors. In this paper, we discuss the operation of a beta-ray energy spectrometer based on a two element, E × dE detector telescope intended to support dose algorithms with beta spectral information. Beta energies are measured via a 5 cm diameter × 2 cm thick BC-404 plastic scintillator preceded by a single, 100 μm thick, totally depleted, silicon dE detector. Photon events in the E detector are rejected by requiring a coincidence between the E and dE detectors. Photon rejection ratios vary from 225:1 at 1.25 MeV (60Co) to 360:1 at 0.36 MeV (133Ba). The spectrometer is capable of measuring electron energies from a lower energy coincidence threshold of approximately 125 keV to an upper limit of 3.5 MeV. This energy range spans the great majority of beta-emitting radionuclides in nuclear facilities.

Performance testing of the environmental TLD system for the Three Mile Island Nuclear Station.

PubMed

Toke, L F; Carson, B H; Baker, G G; McBride, M H; Plato, P A; Miklos, J A

1984-05-01

Panasonic UD-801 thermoluminescent dosimeters ( TLDs ) containing two calcium sulfate phosphors were tested under Performance Specification 3.1 established by the American National Standard Institute ( ANSI75 ) and in the U.S. Nuclear Regulatory Commission's Regulatory Guide 4.13 ( NRC77 ). The specific qualifying tests included TLD uniformity, reproducibility, energy dependence and directional dependence. The overall measurement uncertainties and associated confidence levels are within the prescribed guidelines defined in the qualifying requirements for environmental TLDs .

Error Analysis of non-TLD HDR Brachytherapy Dosimetric Techniques

NASA Astrophysics Data System (ADS)

Amoush, Ahmad

The American Association of Physicists in Medicine Task Group Report43 (AAPM-TG43) and its updated version TG-43U1 rely on the LiF TLD detector to determine the experimental absolute dose rate for brachytherapy. The recommended uncertainty estimates associated with TLD experimental dosimetry include 5% for statistical errors (Type A) and 7% for systematic errors (Type B). TG-43U1 protocol does not include recommendation for other experimental dosimetric techniques to calculate the absolute dose for brachytherapy. This research used two independent experimental methods and Monte Carlo simulations to investigate and analyze uncertainties and errors associated with absolute dosimetry of HDR brachytherapy for a Tandem applicator. An A16 MicroChamber* and one dose MOSFET detectors† were selected to meet the TG-43U1 recommendations for experimental dosimetry. Statistical and systematic uncertainty analyses associated with each experimental technique were analyzed quantitatively using MCNPX 2.6‡ to evaluate source positional error, Tandem positional error, the source spectrum, phantom size effect, reproducibility, temperature and pressure effects, volume averaging, stem and wall effects, and Tandem effect. Absolute dose calculations for clinical use are based on Treatment Planning System (TPS) with no corrections for the above uncertainties. Absolute dose and uncertainties along the transverse plane were predicted for the A16 microchamber. The generated overall uncertainties are 22%, 17%, 15%, 15%, 16%, 17%, and 19% at 1cm, 2cm, 3cm, 4cm, and 5cm, respectively. Predicting the dose beyond 5cm is complicated due to low signal-to-noise ratio, cable effect, and stem effect for the A16 microchamber. Since dose beyond 5cm adds no clinical information, it has been ignored in this study. The absolute dose was predicted for the MOSFET detector from 1cm to 7cm along the transverse plane. The generated overall uncertainties are 23%, 11%, 8%, 7%, 7%, 9%, and 8% at 1cm, 2cm, 3cm

Evaluation of the Energy Distribution of Unknown Photon Radiation Fields by Interpreting the Responses of Tld's and Modification of Burlin Cavity Theory.

NASA Astrophysics Data System (ADS)

Abdulhay, Ibrahim Shakib

1995-01-01

The thermoluminescent dosimeter (TLD) response (integrated light output per unit exposure) of a high Z material increases more rapidly with decreasing photon energy and with energy above the pair production threshold than that of lower Z materials. The ratio of the responses obtained when two thermoluminescent dosimeter (TLD) materials are simultaneously exposed to gamma or x-rays could be used to obtain information about the incident photon energies. In addition, the responses are affected by the presence of the material surrounding the dosimeters. Two TLD's, LiF and CaSO_4, with respective effective atomic number of 8.2 and 15.3, have been chosen to be sandwiched between different absorber materials (Al, Cu, and Pb) and irradiated at selected distances from gamma radiation sources. The photon energies used in this investigation were 60 keV, 142 keV, 662 keV, 1.25 MeV, and 6.129 MeV. Fit equations of the responses of the dosimeters to different energies have been obtained and used to evaluate the energy distributions of unknown ionizing radiation fields. In addition, the electron mass attenuation coefficient beta used in Burlin and Burlin-Horowitz Cavity Theory has been modified to produce better agreement with experimental data at low photon energies and at high energies.

Monte Carlo simulation of depth-dose distributions in TLD-100 under 90Sr-90Y irradiation.

PubMed

Rodríguez-Villafuerte, M; Gamboa-deBuen, I; Brandan, M E

1997-04-01

In this work the depth-dose distribution in TLD-100 dosimeters under beta irradiation from a 90Sr-90Y source was investigated using the Monte Carlo method. Comparisons between the simulated data and experimental results showed that the depth-dose distribution is strongly affected by the different components of both the source and dosimeter holders due to the large number of electron scattering events.

A study of a tissue equivalent gelatine based tissue substitute

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

Spence, J.L.

1992-11-01

A study of several tissue substitutes for use as volumetric dosimeters was performed. The tissue substitutes studied included tissue substitutes from previous studies and from ICRU 44. The substitutes were evaluated for an overall match to Reference Man which was used as a basis for this study. The evaluation was based on the electron stopping power, the mass attenuation coefficient, the electron density, and the specific gravity. The tissue substitute chosen also had to be capable of changing from a liquid into a solid form to maintain an even distribution of thermoluminesent dosimetry (TLD) powder and then back to amore » liquid for recovery of the TLD powder without adversely effecting the TLD powder. The gelatine mixture provided the closest match to the data from Reference Man tissue. The gelatine mixture was put through a series of test to determine it's usefulness as a reliable tissue substitute. The TLD powder was cast in the gelatine mixture and recovered to determine if the TLD powder was adversely effected. The distribution of the TLD powder after being cast into the gelatin mixture was tested in insure an even was maintained.« less

A study of a tissue equivalent gelatine based tissue substitute

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

Spence, Jody L.

1992-11-01

A study of several tissue substitutes for use as volumetric dosimeters was performed. The tissue substitutes studied included tissue substitutes from previous studies and from ICRU 44. The substitutes were evaluated for an overall match to Reference Man which was used as a basis for this study. The evaluation was based on the electron stopping power, the mass attenuation coefficient, the electron density, and the specific gravity. The tissue substitute chosen also had to be capable of changing from a liquid into a solid form to maintain an even distribution of thermoluminesent dosimetry (TLD) powder and then back to amore » liquid for recovery of the TLD powder without adversely effecting the TLD powder. The gelatine mixture provided the closest match to the data from Reference Man tissue. The gelatine mixture was put through a series of test to determine it`s usefulness as a reliable tissue substitute. The TLD powder was cast in the gelatine mixture and recovered to determine if the TLD powder was adversely effected. The distribution of the TLD powder after being cast into the gelatin mixture was tested in insure an even was maintained.« less

On the determination of the post-irradiation time from the glow curve of TLD-100.

PubMed

Weinstein, M; German, U; Dubinsky, S; Alfassi, Z B

2003-01-01

The ratio of peak 3 to the sum of peaks 4 + 5 in TLD-100 was measured for various pre-irradiation and post-irradiation time periods, under conditions characteristic of routine personal dosimetry. It was confirmed that the value of this ratio depends only on the elapsed time between the prior readout and the present one, independent of the moment when the irradiation took place during the total time interval (storage time). This effect indicates that fading of peak 3 seems to be due mainly to changes in the unoccupied traps, and not to decay of trapped charges, being almost independent of the presence of electrons or holes in the traps. This observation leads to the conclusion that the suggestions in the past to use the decay of peak 3 in TLD-100 for the measurement of the elapsed time between irradiation and readout may have been wrong. On the other hand, the decay of peak 2 can be used to measure the elapsed time from irradiation, since the rate of decay is different when related to pre-irradiation and post-irradiation times, indicating a much higher decay rate of the trapped charges (Randall-Wilkins decay). However, because of the fast decay rate of peak 2, its use for determination of the elapsed time since irradiation is of little practical significance.

Determination of the Sensibility Factors for TLD-100 Powder on the Energy of X-Ray of 50, 250 kVp; 192Ir, 137Cs and 60Co

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

Loaiza, Sandra P.; Alvarez, Jose T.

2006-09-08

TLD-100 powder is calibrated in terms of absorbed dose to water Dw, using the protocols AAPM TG61, AAPM TG43 and IAEA-TRS 398, for the energy of RX 50, 250 kVp, 137Cs and 60Co respectively. The calibration curves, TLD Response R versus Dw, are fitted by weighted least square by a quadratic polynomials; which are validated with the lack of fit and the Anderson-Darling normality test. The slope of these curves corresponds to the sensibility factor: Fs R/DW, [Fs] = nC Gy-1. The expanded uncertainties U's for these factors are obtained from the ANOVA tables. Later, the Fs' values are interpolatedmore » using the effective energy hvefec for the 192Ir. The SSDL sent a set of capsules with powder TLD-100 for two Hospitals. These irradiated them a nominal dose of Dw = 2 Gy. The results determined at SSDL are: for the Hospital A the Dw is overestimated in order to 4.8% and the Hospital B underestimates it in the range from -1.4% to -17.5%.« less

SU-E-T-118: Dose Verification for Accuboost Applicators Using TLD, Ion Chamber and Gafchromic Film Measurements

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

Chisela, W; Yao, R; Dorbu, G

Purpose: To verify dose delivered with HDR Accuboost applicators using TLD, ion chamber and Gafchromic film measurements and to examine applicator leakage. Methods: A microSelectron HDR unit was used to deliver a dose of 50cGy to the mid-plane of a 62mm thick solid water phantom using dwell times from Monte Carlo pre-calculated nomograms for a 60mm, 70mm Round and 60mm Skin-Dose Optimized (SDO) applicators respectively. GafChromic EBT3+ film was embedded in the phantom midplane horizontally to measure dose distribution. Absolute dose was also measured with TLDs and an ADCL calibrated parallel-plate ion chamber placed in the film plane at fieldmore » center for each applicator. The film was calibrated using 6MV x-ray beam. TLDs were calibrated in a Cs-137 source at UW-Madison calibration laboratory. Radiation leakage through the tungsten alloy shell was measured with a film wrapped around outside surface of a 60mm Round applicator. Results: Measured maximum doses at field center are consistently lower than predicated by 5.8% for TLD, 8.8% for ion chamber, and 2.6% for EBT3+ film on average, with measurement uncertainties of 2.2%, 0.3%, and 2.9% for TLD, chamber, film respectively. The total standard uncertainties for ion chamber and Gafchromic film measurement are 4.9% and 4.6% respectively[1]. The area defined by the applicator aperture was covered by 80% of maximum dose for 62mm compression thickness. When 100cGy is delivered to mid-plane with a 60mm Round applicator, surface dose ranges from 60cGy to a maximum of 145cGy, which occurs at source entrance to the applicator. Conclusion: Measured doses by all three techniques are consistently lower than predicted in our measurements. For a compression thickness of 62 mm, the field size defined by the applicator is only covered by 80% of prescribed dose. Radiation leakage of up to 145cGy was found at the source entrance of applicators.« less

Neutron measurement at the thermal column of the Malaysian Triga Mark II reactor using gold foil activation method and TLD

NASA Astrophysics Data System (ADS)

Shalbi, Safwan; Salleh, Wan Norhayati Wan; Mohamad Idris, Faridah; Aliff Ashraff Rosdi, Muhammad; Syahir Sarkawi, Muhammad; Liyana Jamsari, Nur; Nasir, Nur Aishah Mohd

2018-01-01

In order to design facilities for boron neutron capture therapy (BNCT), the neutron measurement must be considered to obtain the optimal design of BNCT facility such as collimator and shielding. The previous feasibility study showed that the thermal column could generate higher thermal neutrons yield for BNCT application at the TRIGA MARK II reactor. Currently, the facility for BNCT are planned to be developed at thermal column. Thus, the main objective was focused on the thermal neutron and epithermal neutron flux measurement at the thermal column. In this measurement, pure gold and cadmium were used as a filter to obtain the thermal and epithermal neutron fluxes from inside and outside of the thermal column door of the 200kW reactor power using a gold foil activation method. The results were compared with neutron fluxes using TLD 600 and TLD 700. The outcome of this work will become the benchmark for the design of BNCT collimator and the shielding

Thermoluminescent response of TLD-100 irradiated with 20 keV electrons and the use of radiochromic dye films for the fluence determination

NASA Astrophysics Data System (ADS)

Mercado-Uribe, H.; Brandan, M. E.

2004-07-01

We have measured the LiF:Mg,Ti (TLD-100) fluence response and supralinearity function to 20 keV electrons in the fluence interval between 5 × 10 9 and 4 × 10 12 cm -2. TLD-100 shows linear response up to 2 × 10 10 cm -2, followed by supralinearity and saturation after 10 12 cm -2. Peak 5 is slightly supralinear, f( n) max=1.1±0.1, while high temperature peaks reach up to f( n) max≈8. Peak 5 saturates at n≈1×10 11 cm -2, fluence smaller than any of the saturating fluences of the high temperature peaks. We have also measured the glow curve shape of TLD-100 irradiated with 40 keV electrons, beta particles from a 90Sr/ 90Y source and 1.3 and 6.0 MeV electrons from accelerators. Results are interesting and unexpected in that, for a given macroscopic dose, electrons show a smaller relative contribution of high-temperature peaks with respect to peak 5 than heavy ions or X- and γ-rays. The 20 and 40 keV electron irradiations were performed with a scanning electron microscope using radiochromic dye film to measure fluence. Since film calibrations were performed using 60Co γ-rays which expose the totality of the film volume, the use of this method with low energy electrons required to develop a formalism that takes into account the sensitive thickness of the film in relation to the range of the incident particles.

Evaluation of effective dose for a patient under Ga-67 nuclear examination using TLD, water phantom and a simplified model

PubMed Central

Chu, Kuang Hua; Lin, Yu Ting; Hsu, Chia Chun; Chen, Chien Yi; Pan, Lung Kwang

2012-01-01

This study evaluated the effective dose of Ga-67 for a patient undergoing Ga-67 citrate nuclear examination by applying thermoluminescent dosimeter (TLD) technique and an indigenous water phantom. The Ga-67 radionuclide remaining in the body inevitably generated a measurable internal dose even though gamma camera scanning took only minutes to complete the clinical examination. For effective simulation of the cumulated effective dose for a patient undergoing examination, 150 TLDs were placed inside the water phantom for 6 days to monitor the gamma ray dose from the distributed Ga-67 citrate solution. The inserted TLDs represented internal organs, and the effective dose was calculated according to data in the ICRP-60 report. The water phantom was designed to model the body of a healthy human weighing 70 kg, and the water that was mixed with Ga-67 citrate solution was slowly replaced with fresh feed water to yield the required biological half life of the phantom. After continuously feeding in fresh water throughout the 6 days of TLD exposure, the TLDs were analyzed to determine the effective doses from the various biological half lives of the phantom. The derived effective dose of 185 MBq Ga-67 citrate solution for male/female (M/F) was 10.7/12.2, 10.7/12.0, 8.7/9.9 and 6.0/6.8 mSv, of biological half lives of 6.0, 4.5, 3.0 and 1.5 days, respectively. Although these experimental results correlated well with earlier empirical studies, they were lower than most calculated values. The cumulated uncertainty in the effective dose was 12.5–19.4%, which was acceptable in terms of both TLD counting statistic and reproducibility. PMID:22915780

Response of thermoluminescent lithium fluoride (TLD-100) to photon beams of 275, 400, 500, 600, 730, 900, 1200, 1500, and 2500 eV.

PubMed

Carrillo, R E; Pearson, D W; DeLuca, P M; MacKay, J F; Lagally, M G

1994-11-01

LiF:Mg,Ti (TLD-100) extruded ribbons and cleaved crystals were exposed to monoenergetic photons of 275-2550 eV energy to determine their potential usefulness as radiation dosimeters for radiobiology experiments at these energies. The radiation source was synchrotron radiation from the 1 GeV electron storage ring, Aladdin. The authors report TLD response and glow curves for He- and air-annealed dosimeters. The undesirable effects of air annealing increase with decreasing photon penetration in the dosimeter. Under certain experimental conditions, UV radiation produced anomalous bleaching of high-temperature traps. The crystals and the chips presented a supralinear response, Supralinearity factors were determined to be of the order of 1.5 for crystals, and 1.7 for the chips. The authors' results indicate that TLDs are a reliable means to monitor the total energy deposited in irradiated cells and are now used routinely for radiobiology cell irradiations.

Assessing occupational mercury exposures and behaviours of artisanal and small-scale gold miners in Burkina Faso using passive mercury vapour badges.

PubMed

Black, Paleah; Richard, Myrianne; Rossin, Ricardo; Telmer, Kevin

2017-01-01

Artisanal and small-scale gold mining (ASGM) is a crucial economic activity in Burkina Faso, however it is associated with significant mercury exposure and health concerns. The aim of the present study was to assess the level of mercury (Hg) vapour exposures and occupational behaviours at a representative site using Hg vapour monitor badges and questionnaires. To our knowledge this is the first time that personal exposure to Hg vapour during ASGM activities has been reported. The study population were ASGM workers who completed a questionnaire (n=100) or participated with an occupational exposure assessment using commercially available passive Hg vapour samplers (n=44). Occupational exposure to Hg was high during open-air burn events with a time weighted average (TWA) exposure of 7026±6857µg/m 3 for burners, and 1412±2870µg/m 3 for bystanders. Most (82%) of the people present at the burn exceeded the Permissible Exposure Limit (PEL) of 100µg/m 3 , and 11% exceeded the level considered to be Immediately Dangerous to Life and Health (IDLH) of 10,000µg/m 3 . Even control workers who were not present at the burn exceeded the PEL (24%), likely due to legacy Hg contamination producing latent Hg releases to the atmosphere. Similarly, 86% of the miners at the burn and 59% of control workers had an 8-h TWA that exceeded the Recommended Exposures Limit (REL). Several occupational behaviours that may contribute to Hg exposures were documented. This study corroborates previous studies suggesting that Hg exposure during amalgam burning is very high, and demonstrates the plausibility of using passive vapour monitoring badges rather than costly and logistically difficult biomonitoring methods. Mercury reduction and elimination interventions are strongly needed to reduce Hg exposure in ASGM communities, particularly as countries come into compliance with the Minamata Convention. Copyright © 2016 Elsevier Inc. All rights reserved.

Evaluation of the uncertainties in the TLD radiosurgery postal dose system

NASA Astrophysics Data System (ADS)

Campos, L. T.; Leite, S. P.; de Almeida, C. E. V.; Magalhães, L. A. G.

2018-03-01

Stereotactic radiosurgery is a single-fraction radiation therapy procedure for treating intracranial lesions using a stereotactic apparatus and multiple narrow beams delivered through noncoplanar isocentric arcs. To guarantee a high quality standard, a comprehensive Quality Assurance programme is extremely important to ensure that the measured dose is consistent with the tolerance considered to improve treatment quality. The Radiological Science Laboratory operates a postal audit programme in SRT and SRS. The purpose of the programme is to verify the target localization accuracy in known geometry and the dosimetric conditions of the TPS. The programme works in such a way those thermoluminescence dosimeters, consisting of LiF chips, are sent to the centre where they are to be irradiated to a certain dose. The TLD are then returned, where they are evaluated and the absorbed dose is obtained from TLDs readings. The aim of the present work is estimate the uncertainties in the process of dose determination, using experimental data.

SU-E-T-222: Investigation of Pre and Post Irradiation Fading of the TLD100 Thermoluminescence Dosimetry for Photon Beams

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

Sina, S; Sadeghi, M; Faghihi, R

2014-06-01

Purpose: The pre-irradiation and post-irradiation fading of the Thermoluminescense dosimeter signals were investigated in this study. Methods: Two groups of TLD chips with pre-determined ECC values were used in this study. The two groups were divided into 6 series, each composing of 5 TLD chips.The first group was used for pre-irradiation fading. 5 TLDs were exposed to a known amount of radiation from Cs-137 source, and were read out the next day. After seven days, the other 5 TLDs were exposed to the same amount of radiation and were read out after a day. The other series of 5 TLDsmore » were also exposed after 7,19,28, 59, and 90 days, and were read out a day after irradiation. The loss in TLD signal were obtained for all the above cases. The second group, was used for postirradiation fading. All the TLDs of this group were exposed to a known amount of radiation from Cs-137 source. The 6 series composed of 5 TLDs were read out after 1,7,19,28,59, and 90 days. The above-mentioned procedures for obtaining pre-irradiation, and post-irradiation fading were performed for three storage temperatures (25°C, 4°C, and −18°C). Results: According to the results obtained in this study, in case of pre-irradiation fading study, the signal losses after 90 days are 12%, 24%, and 17% for 25°C, 4°C, and −18°C respectively. In case of post-irradiation fading study, the sensitivity losses after 90 days are 25%, 216%, and 20% for 25°C, 4°C, and −18°C respectively. Conclusion: The results indicate that the optimized time between exposing and reading out, and also the optimized time between annealing and exposing is 1 day.The reduction of Storage temperature will reduce the post-irradiation fading, While temperature reduction does not have any effect on pre-irradiation fading.« less

MCNP SIMULATION OF THE HP(10) ENERGY RESPONSE OF A BRAZILIAN TLD ALBEDO NEUTRON INDIVIDUAL DOSEMETER, FROM THERMAL TO 20 MeV.

PubMed

Freitas, B M; Martins, M M; Pereira, W W; da Silva, A X; Mauricio, C L P

2016-09-01

The Brazilian Instituto de Radioproteção e Dosimetria (IRD) runs a neutron individual monitoring system with a home-made TLD albedo dosemeter. It has already been characterised and calibrated in some reference fields. However, the complete energy response of this dosemeter is not known, and the calibration factors for all monitored workplace neutron fields are difficult to be obtained experimentally. Therefore, to overcome such difficulties, Monte Carlo simulations have been used. This paper describes the simulation of the HP(10) neutron response of the IRD TLD albedo dosemeter using the MCNPX transport code, for energies from thermal to 20 MeV. The validation of the MCNPX modelling is done comparing the simulated results with the experimental measurements for ISO standard neutron fields of (241)Am-Be, (252)Cf, (241)Am-B and (252)Cf(D2O) and also for (241)Am-Be source moderated with paraffin and silicone. Bare (252)Cf are used for normalisation. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Energy dependence of the response of lithium fluoride TLD rods in high energy electron fields.

PubMed

Holt, J G; Edelstein, G R; Clark, T E

1975-07-01

The energy dependence of lithium fluoride dosemeters is a complicated function of energy as well as of cavity size. In the application of TLD to charged particle dosimetry, a cavity perturbation effect may exist even though the ratios of the mass stopping powers are constant over the energies encountered. This effect was investigated for lithium fluoride rods in electron fields ranging in energy from 2-5 to 20 MeV. A 13% change of TL response per unit of absorbed dose was measured over that energy range. A semi-empirical theory was developed to account for the cavity effect, using Burlin cavity theory as a starting point. The agreement between theory and measurement is satisfactory.

Characterization of TLD-100 micro-cubes for use in small field dosimetry

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

Peña-Jiménez, Salvador, E-mail: zoid-9861@yahoo.com.mx; Gamboa-deBuen, Isabel, E-mail: gamboa@nucleares.unam.mx; Lárraga-Gutiérrez, José Manuel, E-mail: jose.larraga.gtz@gmail.com, E-mail: amanda.garcia.g@gmail.com

At present there are no international regulations for the management of millimeter scale fields and there are no suggestions for a reference detector to perform the characterization and dose determination for unconventional radiation beams (small fields) so that the dosimetry of small fields remains an open research field worldwide because these fields are used in radiotherapy treatments. Sensitivity factors and reproducibility of TLD-100 micro-cubes (1×1×1 mm3) were determinate irradiating the dosimeters with a 6 MV beam in a linear accelerator dedicated to radiosurgery at the Instituto Nacional de Neurología y Neurocirugía (INNN). Thermoluminescent response as a function of dose wasmore » determined for doses in water between 0.5 and 3 Gy and two field sizes (2×2 cm2 and 10×10 cm2). It was found that the response is linear over the dose range studied and it does not depend on field size.« less

Characterization of TLD-100 micro-cubes for use in small field dosimetry

NASA Astrophysics Data System (ADS)

Peña-Jiménez, Salvador; Lárraga-Gutiérrez, José Manuel; García-Garduño, Olivia Amanda; Gamboa-deBuen, Isabel

2014-11-01

At present there are no international regulations for the management of millimeter scale fields and there are no suggestions for a reference detector to perform the characterization and dose determination for unconventional radiation beams (small fields) so that the dosimetry of small fields remains an open research field worldwide because these fields are used in radiotherapy treatments. Sensitivity factors and reproducibility of TLD-100 micro-cubes (1×1×1 mm3) were determinate irradiating the dosimeters with a 6 MV beam in a linear accelerator dedicated to radiosurgery at the Instituto Nacional de Neurología y Neurocirugía (INNN). Thermoluminescent response as a function of dose was determined for doses in water between 0.5 and 3 Gy and two field sizes (2×2 cm2 and 10×10 cm2). It was found that the response is linear over the dose range studied and it does not depend on field size.

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SU-E-T-354: Peak Temperature Ratio of TLD Glow Curves to Investigate the Spatial Dependence of LET in a Clinical Proton Beam

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

Reft, C; Pankuch, M; Ramirez, H

Purpose: Use the ratio of the two high temperature peaks (HTR) in TLD 700 glow curves to investigate spatial dependence of the linear energy transfer (LET) in proton beams. Studies show that the relative biological effectiveness (RBE) depends upon the physical dose as well as its spatial distribution. Although proton therapy uses a spatially invariant RBE of 1.1, studies suggest that the RBE increases in the distal edge of a spread out Bragg peak (SOBP) due to the increased LET. Methods: Glow curve studies in TLD 700 show that the 280 C temperature peak is more sensitive to LET radiationmore » than the 210 C temperature peak. Therefore, the areas under the individual temperature peaks for TLDs irradiated in a proton beam normalized to the peak ratio for 6 MV photons are used to determine the HTR to obtain information on its LET. TLD 700 chips with dimensions 0.31×0.31×0.038 cc are irradiated with 90 MeV protons at varying depths in a specially designed blue wax phantom to investigate LET spatial dependence. Results: Five TLDs were placed at five different depths of the percent depth dose curve (PDD) of range 16.2 cm: center of the SOPB and approximately at the 99% distal edge, 90%, 75% and 25% of the PDD, respectively. HTR was 1.3 at the center of the SOBP and varied from 2.2 to 3.9 which can be related to an LET variation from 0.5 to 18 KeV/μ via calibration with radiation beams of varying LET. Conclusion: HTR data show a spatially invariant LET slightly greater than the 6 MV radiations in the SOBP, but a rapidly increasing LET at the end of the proton range. These results indicate a spatial variation in RBE with potential treatment consequences when selecting treatment margins to minimize the uncertainties in proton RBE.« less

Phenomenological study of the ionisation density-dependence of TLD-100 peak 5a.

PubMed

Brandan, Maria-Ester; Angeles, Oscar; Mercado-Uribe, Hilda

2006-01-01

Horowitz and collaborators have reported evidence on the structure of TLD-100 peak 5. A satellite peak, called 5a, has been singled out as arising from localised electron-hole recombination in a trap/luminescent centre, its emission mechanism would be geminate recombination and, therefore, its population would depend on incident radiation ionisation density. We report a phenomenological study of peak 4, 5a and 5 strengths for glow curves previously measured at UNAM for gammas, electrons and low-energy ions. The deconvolution procedure has followed strict rules to assure that the glow curve, where the presence of peak 5a is not visually noticeable, is decomposed in a consistent fashion, maintaining fixed widths and relative temperature difference between all the peaks. We find no improvement in the quality of the fit after inclusion of peak 5a. The relative contribution of peak 5a with respect to peak 5 does not seem to correlate with the radiation linear energy transfer.

How honest are the signals? A protocol for validating wearable sensors.

PubMed

Kayhan, Varol Onur; Chen, Zheng Chris; French, Kimberly A; Allen, Tammy D; Salomon, Kristen; Watkins, Alison

2018-02-01

There is growing interest among organizational researchers in tapping into alternative sources of data beyond self-reports to provide a new avenue for measuring behavioral constructs. Use of alternative data sources such as wearable sensors is necessary for developing theory and enhancing organizational practice. Although wearable sensors are now commercially available, the veracity of the data they capture is largely unknown and mostly based on manufacturers' claims. The goal of this research is to test the validity and reliability of data captured by one such wearable badge (by Humanyze) in the context of structured meetings where all individuals wear a badge for the duration of the encounter. We developed a series of studies, each targeting a specific sensor of this badge that is relevant for structured meetings, and we make specific recommendations for badge data usage based on our validation results. We have incorporated the insights from our studies on a website that researchers can use to conduct validation tests for their badges, upload their data, and assess the validity of the data. We discuss this website in the corresponding studies.

Assessment of the dose distribution inside a cardiac cath lab using TLD measurements and Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Baptista, M.; Teles, P.; Cardoso, G.; Vaz, P.

2014-11-01

Over the last decade, there was a substantial increase in the number of interventional cardiology procedures worldwide, and the corresponding ionizing radiation doses for both the medical staff and patients became a subject of concern. Interventional procedures in cardiology are normally very complex, resulting in long exposure times. Also, these interventions require the operator to work near the patient and, consequently, close to the primary X-ray beam. Moreover, due to the scattered radiation from the patient and the equipment, the medical staff is also exposed to a non-uniform radiation field that can lead to a significant exposure of sensitive body organs and tissues, such as the eye lens, the thyroid and the extremities. In order to better understand the spatial variation of the dose and dose rate distributions during an interventional cardiology procedure, the dose distribution around a C-arm fluoroscopic system, in operation in a cardiac cath lab at Portuguese Hospital, was estimated using both Monte Carlo (MC) simulations and dosimetric measurements. To model and simulate the cardiac cath lab, including the fluoroscopic equipment used to execute interventional procedures, the state-of-the-art MC radiation transport code MCNPX 2.7.0 was used. Subsequently, Thermo-Luminescent Detector (TLD) measurements were performed, in order to validate and support the simulation results obtained for the cath lab model. The preliminary results presented in this study reveal that the cardiac cath lab model was successfully validated, taking into account the good agreement between MC calculations and TLD measurements. The simulated results for the isodose curves related to the C-arm fluoroscopic system are also consistent with the dosimetric information provided by the equipment manufacturer (Siemens). The adequacy of the implemented computational model used to simulate complex procedures and map dose distributions around the operator and the medical staff is discussed, in

In vivo dosimetry with TLD in conservative treatment of breast cancer patients treated with the EORTC protocol 22881.

PubMed

Hamers, H P; Johansson, K A; Venselaar, J L; de Brouwer, P; Hansson, U; Moudi, C

1993-01-01

Two anthropomorphic phantom breasts and six patients with breast carcinoma were irradiated according the prescriptions of the EORTC protocol 22881 on the conservative management of breast carcinoma by tumorectomy and radiotherapy. During the implantation procedure for an iridium-192 boost, three tubes were implanted, enabling the measurement with TLD rods of the dose within the breasts of the phantom and the patients during one fraction of the external x-ray therapy and during the interstitial therapy. Measured doses were compared with calculated values from a 2-D dose planning system. In general a fair agreement was found between the measured and calculated doses in points within the breast for the external beam therapy as well as for the interstitial treatment.

On the effect of updated MCNP photon cross section data on the simulated response of the HPA TLD.

PubMed

Eakins, Jonathan

2009-02-01

The relative response of the new Health Protection Agency thermoluminescence dosimeter (TLD) has been calculated for Narrow Series X-ray distribution and (137)Cs photon sources using the Monte Carlo code MCNP5, and the results compared with those obtained during its design stage using the predecessor code, MCNP4c2. The results agreed at intermediate energies (approximately 0.1 MeV to (137)Cs), but differed at low energies (<0.1 MeV) by up to approximately 10%. This disparity has been ascribed to differences in the default photon interaction data used by the two codes, and derives ultimately from the effect on absorbed dose of the recent updates to the photoelectric cross sections. The sources of these data have been reviewed.

Intensity variation study of the radiation field in a mammographic system using thermoluminescent dosimeters TLD-900 (CaSO4:Dy)

NASA Astrophysics Data System (ADS)

Corrêa, E. L.; Silva, J. O.; Vivolo, V.; Potiens, M. P. A.; Daros, K. A. C.; Medeiros, R. B.

2014-02-01

This study presents the results of the intensity variation of the radiation field in a mammographic system using the thermoluminescent dosimeter TLD-900 (CaSO4:Dy). These TLDs were calibrated and characterized in an industrial X-ray system used for instruments calibration, in the energy range used in mammography. They were distributed in a matrix of 19 lines and five columns, covering an area of 18 cm×8 cm in the center of the radiation field on the clinical equipment. The results showed a variation of the intensity probably explained by the non-uniformity of the field due to the heel effect.

Response analysis of TLD-300 dosimeters in heavy-particle beams.

PubMed

Loncol, T; Hamal, M; Denis, J M; Vynckier, S; Wambersie, A; Scalliet, P

1996-09-01

In vivo dosimetry is recommended as part of the quality control procedure for treatment verification in radiation therapy. Using thermoluminescence, such controls are planned in the p(65) + Be neutron and 85 MeV proton beams produced at the cyclotron at Louvain-La-Neuve and dedicated to therapy applications. A preliminary study of the peak 3 (150 degrees C) and peak 5 (250 degrees C) response of CaF2:Tm (TLD-300) to neutron and proton beams aimed to analyse the effect of different radiation qualities on the dosimetric behaviour of the detector irradiated in phantom. To broaden the range of investigation, the study was extended to an experimental 12C heavy ion beam (95 MeV/nucleon). The peak 3 and 5 sensitivities in the neutron beam, compared to 60Co, varied little with depth. A major change of peak 5 sensitivity was observed for samples positioned under five leaves of the multi-leaf collimator. While peak 3 sensitivity was constant with depth in the unmodulated proton beam, peak 5 sensitivity increased by 15%. Near the Bragg peak, peak 3 showed the highest decrease of sensitivity. In the modulated proton beam, the sensitivity values were not significantly smaller than those measured in the unmodulated beam far from the Bragg peak region. The ratio of the heights of peak 3 and peak 5 decreased by 70% from the 60Co reference radiation to the 12C heavy-ion beam. This parameter was strongly correlated with the change of radiation quality.

Dose measurements in space by the Hungarian Pille TLD system.

PubMed

Apathy, I; Deme, S; Feher, I; Akatov, Y A; Reitz, G; Arkhanguelski, V V

2002-10-01

Exposure of crew, equipment, and experiments to the ambient space radiation environment in low Earth orbit poses one of the most significant problems to long-term space habitation. Accurate dose measurement has become increasingly important during the assembly (extravehicular activity (EVA)) and operation of space stations such as on Space Station Mir. Passive integrating detector systems such as thermoluminescent dosemeters (TLDs) are commonly used for dosimetry mapping and personal dosimetry on space vehicles. The well-known advantages of passive detector systems are their independence of power supply, small dimensions, high sensitivity, good stability, wide measuring range, resistance to environmental effects, and relatively low cost. Nevertheless, they have the general disadvantage that for evaluation purposes they need a laboratory or large--in mass and power consumption--terrestrial equipment, and consequently they cannot provide time-resolved dose data during long-term space flights. KFKI Atomic Energy Research Institute (KFKI AEKI) has developed and manufactured a series of thermoluminescent dosemeter systems for measuring cosmic radiation doses in the 10 microGy to 10 Gy range, consisting of a set of bulb dosemeters and a compact, self-contained, TLD reader suitable for on-board evaluation of the dosemeters. By means of such a system, highly accurate measurements were carried out on board the Salyut-6, -7 and Mir Space Stations as well as on the Space Shuttle. A detailed description of the system is given and the comprehensive results of these measurements are summarised. c2002 Elsevier Science Ltd. All rights reserved.

A Monte Carlo study of the quality dependence factors of common TLD materials in photon and electron beams.

PubMed

Mobit, P N; Nahum, A E; Mayles, P

1998-08-01

A Monte Carlo simulation of the quality dependence of different TL materials, in the form of discs 3.61 mm in diameter and 0.9 mm thick, in radiotherapy photon beams relative to 60Co gamma-rays has been performed. The beam qualities ranged from 50 kV to 25 MV x-rays. The TL materials were: CaF2, CaSO4, LiF and Li2B4O7. The effects of the dopants on energy deposition in the TL material have also been determined for the highly sensitive LiF:Mg:Cu:P (TLD-100H) and for CaF2:Mn. It was found that there was a significant difference in the quality dependence factor derived from Monte Carlo simulations between LiF and LiF:Mg:Cu:P but not between CaF2 and CaF2:Mn. The quality dependence factors for Li2B4O7 varied from 0.990 +/- 0.008 (1 sd) for 25 MV x-rays to 0.940 +/- 0.009 (1 sd) for 50 kV x-rays relative to 60Co gamma-rays; Monte Carlo simulations were also performed for Li2B4O7 in megavoltage electron beams. For CaF2, the quality dependence factor varied from 0.927 +/- 0.008 (1 sd) for 25 MV x-rays to 10.561 +/- 0.008 (1 sd) for 50 kV x-rays. The figure for CaSO4 ranged from 0.943 +/- 0.008 (1 sd) for 25 MV x-rays to 9.010 +/- 0.008 (1 sd) for 50 kV x-rays. The quality dependence factor for CaF2 increases by up to 5% with depth and by up to 15% with field size for the kilovoltage x-ray beams. For LiF-TLD, however, there was no significant dependence on the field size or depth of irradiation in the kilovoltage energy range.

The use of TLD-700H dosemeters in the assessment of external doses at the former Semipalatinsk nuclear test site.

PubMed

Hill, P; Dederichs, H; Pillath, J; Schlecht, W; Hille, R; Artemev, O; Ptitskaya, L; Akhmetov, M

2002-01-01

The joint projects performed since 1995 by the Jülich Research Centre in co-operation with the Kazakh National Nuclear Centre in the area of the former nuclear test site near Semipalatinsk, in eastern Kazakhstan, have assessed the current dose rate of the population at and around the test site, as well as determining retrospectively the dose rate of persons affected by the atmospheric tests. Measurements of the population by personal dosemeters depend on reliably wearing these dosemeters over prolonged periods of time, and of a sufficient dosemeter return. In the past, such measurements have been particularly successful whenever short wearing times were possible. This requires high sensitivity of the dosemeters. The suitability of the highly sensitive TLD material of the BICRON TLD 700H type for such personal dosimetry measurements was investigated. It was tested in practical field application at the Semipalatinsk nuclear test site in September 2000. Initial results are available from individual doses received by a group of geologists and a group of herdsmen at the test site. For the first time, the individual dose was measured directly in these population groups. Detection limits below 1 microSv permit informative measurements for wearing times of less than two weeks. Most individual doses did not arise significantly out of local fluctuations of natural background. A conservative assessment from the aspect of practical health physics yielded a mean personal dose of 0.55 microSv per day for the herdsmen, whereas the geologists received a mean personal dose of 0.45 microSv per day. For an annual exposure period of typically, about three months, the radiation dose received by the persons investigated, in addition to the natural radiation exposure, is thus well below the international limit value of 1 mSv x a(-1) for the population dose.

Poster - 24: Characterization of the energy dependence of high-sensitivity MCP-N TLD and Al2O3:C OSLD in-vivo dosimetry systems for 40–100 kVp energies

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

Poirier, Yannick; Kuznetsova, Svetlana; Barajas, E

Purpose: To characterize the energy dependence of high-sensitivity MCP-N TLD and Al{sub 2}O{sub 3}:C OSLD dosimetry systems at low (40–100 kVp) energies for in-vivo dosimetry. Methods: We assessed the variation of response with energy of two detectors in the 40–100 kVp energy range: high-sensitivity MCP-N TLDs (LiF:Mg,Cu,P) and OSLDs (Al{sub 2}O{sub 3}:C). The detectors were irradiated with an XRad 320ix biological irradiator under reference conditions. The delivered dose was 10 cGy for 7 beam qualities ranging from 40–100 kVp, 1.7–4.0 mm Al, and effective energies 26.9–37.9 keV. Both sets of detectors were also irradiated under reference conditions at 6 MVmore » using a Varian Clinac 21Ex to assess the change in response from high-energy beams. Results: The MCP-N high-sensitivity TLDs were relatively insensitive to energies in the kV range, as their response varied by ±5%, i.e. well within the reproducibility limits of these detectors. However, the OSLDs exhibited a linearly-decreasing response with energy with a response 18.7% higher at 40 kVp than at 100 kVp for the same nominal dose. Compared to the 6 MV beams used in conventional radiotherapy, OSLDs responded 3.3–3.9 times higher depending on beam quality while the MCP-N TLD response was unchanged within experimental uncertainty. Conclusions: Unlike the more commonly used TLD-100, the high-sensitivity MCP-N TLDs exhibit little to no energy response. OSLDs are shown to be highly energy-dependent, both from MV to kV and within the kV range.« less

Dosimetry for Small Fields in Stereotactic Radiosurgery Using Gafchromic MD-V2-55 Film, TLD-100 and Alanine Dosimeters

PubMed Central

Massillon-JL, Guerda; Cueva-Prócel, Diego; Díaz-Aguirre, Porfirio; Rodríguez-Ponce, Miguel; Herrera-Martínez, Flor

2013-01-01

This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK) and a modified linear accelerator (linac) for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55), alanine and thermoluminescent (TLD-100) dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in 60Co gamma-ray and 6 MV x-ray reference (10×10 cm2) fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not appropriate in fields

Response analysis of TLD-300 dosimeters in heavy-particle beams

NASA Astrophysics Data System (ADS)

Loncol, Th; Hamal, M.; Denis, J. M.; Vynckier, S.; Wambersie, A.; Scalliet, P.

1996-09-01

In vivo dosimetry is recommended as part of the quality control procedure for treatment verification in radiation therapy. Using thermoluminescence, such controls are planned in the p(65)+Be neutron and 85 MeV proton beams produced at the cyclotron at Louvain-La-Neuve and dedicated to therapy applications. A preliminary study of the peak 3 (C) and peak 5 (C) response of :Tm (TLD-300) to neutron and proton beams aimed to analyse the effect of different radiation qualities on the dosimetric behaviour of the detector irradiated in phantom. To broaden the range of investigation, the study was extended to an experimental C-12 heavy ion beam (95 MeV/nucleon). The peak 3 and 5 sensitivities in the neutron beam, compared to Co-60, varied little with depth. A major change of peak 5 sensitivity was observed for samples positioned under five leaves of the multi-leaf collimator. While peak 3 sensitivity was constant with depth in the unmodulated proton beam, peak 5 sensitivity increased by 15%. Near the Bragg peak, peak 3 showed the highest decrease of sensitivity. In the modulated proton beam, the sensitivity values were not significantly smaller than those measured in the unmodulated beam far from the Bragg peak region. The ratio of the heights of peak 3 and peak 5 decreased by 70% from the Co-60 reference radiation to the C-12 heavy-ion beam. This parameter was strongly correlated with the change of radiation quality.

SU-E-T-87: Comparison Study of Dose Reconstruction From Cylindrical Diode Array Measurements, with TLD Measurements and Treatment Planning System Calculations in Anthropomorphic Head and Neck and Lung Phantoms

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

Benhabib, S; Cardan, R; Huang, M

Purpose: To assess dose calculated by the 3DVH software (Sun Nuclear Systems, Melbourne, FL) against TLD measurements and treatment planning system calculations in anthropomorphic phantoms. Methods: The IROC Houston (RPC) head and neck (HN) and lung phantoms were scanned and plans were generated using Eclipse (Varian Medical Systems, Milpitas, CA) following IROC Houston procedures. For the H and N phantom, 6 MV VMAT and 9-field dynamic MLC (DMLC) plans were created. For the lung phantom 6 MV VMAT and 15 MV 9-field dynamic MLC (DMLC) plans were created. The plans were delivered to the phantoms and to an ArcCHECK (Sunmore » Nuclear Systems, Melbourne, FL). The head and neck phantom contained 8 TLDs located at PTV1 (4), PTV2 (2), and OAR Cord (2). The lung phantom contained 4 TLDs, 2 in the PTV, 1 in the cord, and 1 in the heart. Daily outputs were recorded before each measurement for correction. 3DVH dose reconstruction software was used to project the calculated dose to patient anatomy. Results: For the HN phantom, the maximum difference between 3DVH and TLDs was -3.4% and between 3DVH and Eclipse was 1.2%. For the lung plan the maximum difference between 3DVH and TLDs was 4.3%, except for the spinal cord for which 3DVH overestimated the TLD dose by 12%. The maximum difference between 3DVH and Eclipse was 0.3%. 3DVH agreed well with Eclipse because the dose reconstruction algorithm uses the diode measurements to perturb the dose calculated by the treatment planning system; therefore, if there is a problem in the modeling or heterogeneity correction, it will be carried through to 3DVH. Conclusion: 3DVH agreed well with Eclipse and TLD measurements. Comparison of 3DVH with film measurements is ongoing. Work supported by PHS grant CA10953 and CA81647 (NCI, DHHS)« less

Extra dose due to extravehicular activity during the NASA4 mission measured by an on-board TLD system.

PubMed

Deme, S; Apathy, I; Hejja, I; Lang, E; Feher, I

1999-01-01

A microprocessor-controlled on-board TLD system, 'Pille'96', was used during the NASA4 (1997) mission to monitor the cosmic radiation dose inside the Mir Space Station and to measure the extra dose to two astronauts in the course of their extravehicular activity (EVA). For the EVA dose measurements, CaSO4:Dy bulb dosemeters were located in specially designed pockets of the ORLAN spacesuits. During an EVA lasting 6 h, the dose ratio inside and outside Mir was measured. During the EVA, Mir crossed the South Atlantic Anomaly (SAA) three times. Taking into account the influence of these three crossings the mean EVA/internal dose rate ratio was 3.2. Internal dose mapping using CaSO4:Dy dosemeters gave mean dose rates ranging from 9.3 to 18.3 microGy h-1 at locations where the shielding effect was not the same. Evaluation results of the high temperature region of LiF dosemeters are given to estimate the mean LET.

32 CFR 218.2 - General procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... approach taken in dose determination: (a) Use individual film badge data where available and complete, for... received estimate is made. (d) If partial film badge data are available, define group(s) of personnel with..., verify from the distribution of film badge readings whether the badged sample adequately represents the...

Is dosimetry still a necessity in current dental practice?

PubMed

Reddy, S S; Rakesh, N; Chauhan, Pallavi; Clint, Joseph Ben; Sharma, Shivani

2015-12-01

Today, dentists have a wide range of imaging modalities to choose from, the film based techniques, digital techniques, and the recent introduction of 3D volumetric or cone beam computed tomography (CBCT). The inherent design features of the new generation dental x-ray equipment has significantly improved over the years with no evidence of substandard x-ray units in operation. In dental facilities radiological workload is comparatively low, newer radiation equipments and accessories follow safety guidelines and employ better radiation protection measures for the patient and the operator. Dentists' knowledge and expertise in radiation protection measures is good, enabling them to carry out riskfree radiation procedures in their practice. Therefore, the present study is aimed at assessing the need for dosimeters in current dental scenario. 'Is there currently a significant risk from dental radiography to merit the use of personal dosimetery in dental practice. 'Dental health professionals (Oral radiologists) and radiographic assistants of fourteen dental colleges in Karnataka state participated in this questionnaire study. The questionnaire consisted of the following questions--the make, type, year of manufacture of radiographic machines used in their setup, number of radiographs made per day in the institution, type of receptors used, number of personnel at risk for radiation exposure, radiation protection measures used, regular monitoring by personal dosimeters, equivalent dosage readings for the past 12 months and whether the reading of thermoluminescent dosimeters (TLD) for any personnel had exceeded the recommended exposure value in the last 3 years. Dosimetry records of the radiology staff in the last three years shows doses no more than 1.50 mSv per year. The various institutions' dose (person mSv) was in the range of 3.70 mSv-3.90 mSv. Personal monitoring for Dentists can be omitted in the dental colleges since the estimated dose of oral radiologists

Efficacy of a radiation absorbing shield in reducing dose to the interventionalist during peripheral endovascular procedures: a single centre pilot study.

PubMed

Power, S; Mirza, M; Thakorlal, A; Ganai, B; Gavagan, L D; Given, M F; Lee, M J

2015-06-01

This prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures. A commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated. TLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142). Initial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator's body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

Passive, Direct-Read Monitoring System for Selective Detection and Quantification of Hydrogen Chloride

NASA Technical Reports Server (NTRS)

Chapman, K. B.; Mihaylov, G. M.; Kirollos, K. S.

2000-01-01

Monitoring the exposure of an employee to hydrogen chloride or hydrochloric acid in the presence of other acids has been a challenge to the industrial hygiene community. The capability of a device to differentiate the levels of acid vapors would allow for more accurate determinations of exposure and therefore improved occupational health. In this work, a selective direct-read colorimetric badge system was validated for Short Term Exposure Limit (STEL) monitoring of hydrogen chloride. The passive colorimetric badge system consists of a direct reading badge and a color scale. The badge has a coated indicator layer with a diffusive resistance in the shape of an exclamation mark. An exclamation mark will appear if hydrogen chloride is present in the atmosphere at concentrations at or above 2.0 ppm. By using the color scale, the intensity of the color formed on the badge can be further quantified up to 25 ppm. The system was validated according to a protocol based on the NIOSH Protocol for the Evaluation of Passive Monitors. The badge was exposed to relative humidities ranging from 11% to 92%, temperatures ranging from 7 C to 400 C and air velocities ranging from 5 cm/sec to 170 cm/sec. All experiments were conducted in a laboratory vapor generation system. Hydrofluoric acid, nitric acid, sulfuric acid, chlorine, hydrogen sulfide and organic acids showed no effect on the performance of the hydrogen chloride monitoring system. The passive badge and color scale system exceeded the accuracy requirements as defined by NIOSH. At ambient conditions, the mean coefficient of variation was 10.86 and the mean bias was 1.3%. This data was presented previously at the American Industrial Hygiene Conference and Exposition in Toronto, Canada in June 1999.

Science education in the Boy Scouts of America

NASA Astrophysics Data System (ADS)

Hintz, Rachel Sterneman

This study of science education in the Boy Scouts of America focused on males with Boy Scout experience. The mixed-methods study topics included: merit badge standards compared with National Science Education Standards, Scout responses to open-ended survey questions, the learning styles of Scouts, a quantitative assessment of science content knowledge acquisition using the Geology merit badge, and a qualitative analysis of interview responses of Scouts, Scout leaders, and scientists who were Scouts. The merit badge requirements of the 121 current merit badges were mapped onto the National Science Education Standards: 103 badges (85.12%) had at least one requirement meeting the National Science Education Standards. In 2007, Scouts earned 1,628,500 merit badges with at least one science requirement, including 72,279 Environmental Science merit badges. "Camping" was the "favorite thing about Scouts" for 54.4% of the boys who completed the survey. When combined with other outdoor activities, what 72.5% of the boys liked best about Boy Scouts involved outdoor activity. The learning styles of Scouts tend to include tactile and/or visual elements. Scouts were more global and integrated than analytical in their thinking patterns; they also had a significant intake element in their learning style. Earning a Geology merit badge at any location resulted in a significant gain of content knowledge; the combined treatment groups for all location types had a 9.13% gain in content knowledge. The amount of content knowledge acquired through the merit badge program varied with location; boys earning the Geology merit badge at summer camp or working as a troop with a merit badge counselor tended to acquire more geology content knowledge than boys earning the merit badge at a one-day event. Boys retained the content knowledge learned while earning the merit badge. Scientists, Scout leaders, and Scouts felt that Scouts learned science through participation in the Boy Scout program

Measurement of 241Am-Be spectra (bare and Pb-covered) using TLD pairs in multi-spheres: Spectrum unfolding by different methods

NASA Astrophysics Data System (ADS)

Tripathy, S. P.; Bakshi, A. K.; Sathian, V.; Tripathi, S. M.; Vega-carrillo, H. R.; Nandy, M.; Sarkar, P. K.; Sharma, D. N.

2009-01-01

The neutron spectra from a Pb-covered and a bare (without Pb-cover) 241Am-Be (α,n) source were measured using thermoluminescent detector (TLD) pairs of 6LiF and 7LiF with high-density polyethylene (HDPE) multi-spheres of seven different diameters. A total of 8 distinct neutron response signals (including a bare mode exposure) were obtained from which the energy distribution for the entire energy range was generated with the help of different neutron spectrum unfolding methods, viz. BUNKI, BUNKIUT and Frascati unfolding interactive tool (FRUIT). Shape of these spectra are matching very well and is also comparable with the standard IAEA 241Am-Be spectrum, thus, validating the unfolding methods used in this work. The effect of Pb-cover on the spectrum and the unfolding details are reported in the paper.

Correlation-based static correction of 4D seismic data with a demonstration at the Ketzin CO2 storage site, Germany

NASA Astrophysics Data System (ADS)

Bergmann, P.; Kashubin, A.; Ivandic, M.; Lueth, S.; Juhlin, C.

2013-12-01

Statics are time-shifts that occur in reflection seismic trace data and are generally considered to be mainly due to shallow velocity variations. Since the refraction static correction is most often based on first break picking and subsequent velocity model estimation, it is even today a labor-consuming and error-prone procedure. Time-lapse seismic also faces this issue in a temporal sense, since changes in statics, due to temporally variable near-surface conditions, are known to be first-order contributors to time-lapse noise. Considerable changes in the statics of repeated on-shore seismic surveys can occur due to precipitation-related changes in soil moisture and in the groundwater table, or may be due to man-made earthworks. Production-related or injection-related processes can cause considerable velocity changes, which leave time-shift imprints on time-lapse seismic data that can be very similar to that of near-surface velocity variations. In this context it is crucial to consider that refraction static corrections are in many cases of limited use, as they aim to enhance the stack coherency of the individual time-lapse data sets only. As an alternative, we propose a time-lapse difference (TLD) static correction that is focused on the accommodation of static changes between the time-lapse data sets. This TLD static correction decomposes the static differences that are determined from cross-correlations in a surface-consistent manner. It therefore does not require first break picking and inversion for velocities from repeat data sets. We tested the TLD static correction for a 4D case study from the Ketzin CO2 storage site, Germany. As a reference we used the results that were obtained from a recent processing in which refraction static corrections were performed individually on the time-lapse data sets. Although the TLD static corrections method is considerably less time-consuming, we found that it is providing a stack difference with enhanced S/N. This is

Energy response of CaSO4:Dy teflon TLD disk dosimeters to photons and electrons.

PubMed

Sharada, K S

1983-01-01

The photon energy response of CaSO4:Dy teflon disk dosimeters used widely in radiation dosimetry is computed using the energy absorption coefficient values for calcium, sulfur, oxygen, and carbon taken from J. H. Hubbell's tables. For fluorine, the energy absorption coefficients were obtained from the values given by F. H. Attix for CaF2 and Ca. The energy response of the radiation-monitoring disk for the range of 10 keV to 10 MeV, relative to air, is computed and plotted. The response is maximum between 20 and 30 keV and then gradually falls to a constant at 200 keV to 10 MeV. This computed response for different energies is compared with the experimental TL response of the dosimeter. The electron energy response of these TLD disks is computed using the stopping-power values for the different component elements. The electron stopping power for sulfur and calcium from 10 keV to 10 MeV is computed using the Bethe-Bloch formula. Those for oxygen and carbon are taken from the tables given by M. J. Berger and S. M. Seltzer. For fluorine, the values are computed from those for Li and LiF given in the same tables. This calculated response is compared with the experimental beta response of the TL dosimeter.

Kinetic modelling of the optically stimulated conversion of peaks 5a and 5 to peak 4 in LiF:Mg,Ti (TLD-100).

PubMed

Weizman, Y; Horowitz, Y S; Oster, L

2002-01-01

The TC/LC conversion model for peaks 4, 5a and 5 in LiF:Mg,Ti (TLD-100) has been studied by solution of the coupled differential equations describing the charge carrier traffic following optical stimulation. Aspects of the model investigated were (i) the two-component exponential decay of the composite peak 5 TL intensity following the bleach, (ii) the role of retrapping during bleaching, (iii) the hole nature of peak 4 and (iv) the conversion of peak 5a traps to peak 4 traps. The high conversion efficiency is naturally explained due to the absence of conduction band competitive mechanisms in the optical ionisation of the electron in the e-h occupied structure corresponding to peak 5a and thereby leading to the hole-only occupied TC/LC leading to peak 4.

STS 118 Return Samples: Assessment of Air Quality aboard the Shuttle (STS-118) and International Space Station

NASA Technical Reports Server (NTRS)

James, John T.

2007-01-01

The toxicological assessments of 2 grab sample canisters (GSCs) and one pair of formaldehyde badges from the Shuttle are reported. Analytical methods have not changed from earlier reports. The recoveries of the 3 surrogates (C-13-acetone, fluorobenzene, and chlorobenzene) from the 2 GSCs averaged 120, 117, and 122 %, respectively. Three formaldehyde controls averaged 98% recovery. The Shuttle atmosphere was acceptable for human respiration. The toxicological assessment of 8 GSCs and 6 pairs of formaldehyde badges from the ISS is shown. The recoveries of the 3 standards (as listed above) from the GSCs averaged 99, 99 and 99%, respectively. Three formaldehyde control badges averaged 98% recovery. Based on these limited samples, the ISS atmosphere is acceptable for human respiration. The alcohol levels were well controlled throughout the period of sampling.

Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

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

Power, S.; Mirza, M.; Thakorlal, A.

PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used tomore » measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.« less

The influence of neutron contamination on dosimetry in external photon beam radiotherapy.

PubMed

Horst, Felix; Czarnecki, Damian; Zink, Klemens

2015-11-01

Photon fields with energies above ∼7 MeV are contaminated by neutrons due to photonuclear reactions. Their influence on dosimetry-although considered to be very low-is widely unexplored. In this work, Monte Carlo based investigations into this issue performed with fluka and egsnrc are presented. A typical Linac head in 18 MV-X mode was modeled equivalently within both codes. egsnrc was used for the photon and fluka for the neutron production and transport simulation. Water depth dose profiles and the response of different detectors (Farmer chamber, TLD-100, TLD-600H, and TLD-700H chip) in five representative depths were simulated and the neutrons' impact (neutron absorbed dose relative to photon absorbed dose) was calculated. To take account of the neutrons' influence, a theoretically required correction factor was defined and calculated for five representative water depths. The neutrons' impact on the absorbed dose to water was found to be below 0.1% for all depths and their impact on the response of the Farmer chamber and the TLD-700H chip was found to be even less. For the TLD-100 and the TLD-600H chip it was found to be up to 0.3% and 0.7%, respectively. The theoretical correction factors to be applied to absorbed dose to water values measured with these four detectors in a depth different from the reference/calibration depth were calculated and found to be below 0.05% for the Farmer chamber and the TLD-700H chip, but up to 0.15% and 0.35% for the TLD-100 and TLD-600H chips, respectively. In thermoluminescence dosimetry the neutrons' influence (and therefore the additional inaccuracy in measurement) was found to be higher for TLD materials whose 6Li fraction is high, such as TLD-100 and TLD-600H, resulting from the thermal neutron capture reaction on 6Li. The impact of photoneutrons on the absorbed dose to water and on the response of a typical ionization chamber as well as three different types of TLD chips was quantified and was as expected found to be very

Upgrading the Neutron Radiography Facility in South Africa (SANRAD): Concrete Shielding Design Characteristics

NASA Astrophysics Data System (ADS)

de Beer, F. C.; Radebe, M. J.; Schillinger, B.; Nshimirimana, R.; Ramushu, M. A.; Modise, T.

A common denominator of all neutron radiography (NRAD) facilities worldwide is that the perimeter of the experimental chamber of the facility is a radiation shielding structure which,in some cases, also includes flight tube and filter chamber structures. These chambers are normally both located on the beam port floor outside the biological shielding of the neutron source. The main function of the NRAD-shielding structure isto maintain a radiological safe working environment in the entire beam hall according to standards set by individual national radiological safety regulations. In addition, the shielding's integrity and capability should not allow, during NRAD operations, an increase in radiation levels in the beam port hall and thus negatively affectadjacent scientific facilities (e.g. neutron diffraction facilities).As a bonus, the shielding for the NRAD facility should also prevent radiation scattering towards the detector plane and doing so, thus increase thecapability of obtaining better quantitative results. This paper addresses Monte Carlo neutron-particletransport simulations to theoretically optimize the shielding capabilities of the biological barrierfor the SANRAD facility at the SAFARI-1 nuclear research reactor in South Africa. The experimental process to develop the shielding, based on the principles of the ANTARES facility, is described. After casting, the homogeneity distribution of these concrete mix materials is found to be near perfect and first order experimental radiation shielding characteristicsthrough film badge (TLD) exposure show acceptable values and trends in neutron- and gamma-ray attenuation.

Angular and radial dependence of the energy response factor for LIF-TLD micro-rods in 125L permanent implant source.

PubMed

Mobit, Paul; Badragan, Iulian

2006-01-01

EGSnrc Monte Carlo simulations were used to calculate the angular and radial dependence of the energy response factor for LiF-thermoluminescence dosemeters (TLDs) irradiated with a commercially available (125)I permanent brachytherapy source. The LiF-TLDs were modelled as cylindrical micro-rods of length 6 mm and with diameters of 1 mm and 5 mm. The results show that for a LiF-TLD micro-rod of 1 mm diameter, the energy response relative to (60)Co gamma rays is 1.406 +/- 0.3% for a polar angle of 90 degrees and radial distance of 1.0 cm. When the diameter of the micro-rod is increased from 1 to 5 mm, the energy response decreases to 1.32 +/- 0.3% at the same point. The variation with position of the energy response factor is not >5% in a 6 cm x 6 cm x 6 cm calculation grid for the 5 mm diameter micro-rod. The results show that there is a change in the photon spectrum with angle and radial distance, which causes the variation of the energy response.

The influence of neutron contamination on dosimetry in external photon beam radiotherapy

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

Horst, Felix, E-mail: felix.ernst.horst@kmub.thm.de; Czarnecki, Damian; Zink, Klemens

Purpose: Photon fields with energies above ∼7 MeV are contaminated by neutrons due to photonuclear reactions. Their influence on dosimetry—although considered to be very low—is widely unexplored. Methods: In this work, Monte Carlo based investigations into this issue performed with FLUKA and EGSNRC are presented. A typical Linac head in 18 MV-X mode was modeled equivalently within both codes. EGSNRC was used for the photon and FLUKA for the neutron production and transport simulation. Water depth dose profiles and the response of different detectors (Farmer chamber, TLD-100, TLD-600H, and TLD-700H chip) in five representative depths were simulated and the neutrons’more » impact (neutron absorbed dose relative to photon absorbed dose) was calculated. To take account of the neutrons’ influence, a theoretically required correction factor was defined and calculated for five representative water depths. Results: The neutrons’ impact on the absorbed dose to water was found to be below 0.1% for all depths and their impact on the response of the Farmer chamber and the TLD-700H chip was found to be even less. For the TLD-100 and the TLD-600H chip it was found to be up to 0.3% and 0.7%, respectively. The theoretical correction factors to be applied to absorbed dose to water values measured with these four detectors in a depth different from the reference/calibration depth were calculated and found to be below 0.05% for the Farmer chamber and the TLD-700H chip, but up to 0.15% and 0.35% for the TLD-100 and TLD-600H chips, respectively. In thermoluminescence dosimetry the neutrons’ influence (and therefore the additional inaccuracy in measurement) was found to be higher for TLD materials whose {sup 6}Li fraction is high, such as TLD-100 and TLD-600H, resulting from the thermal neutron capture reaction on {sup 6}Li. Conclusions: The impact of photoneutrons on the absorbed dose to water and on the response of a typical ionization chamber as well as three

Bisphenol diglycidyl ethers and bisphenol A and their hydrolysis in drinking water.

PubMed

Lane, R F; Adams, C D; Randtke, S J; Carter, R E

2015-04-01

Epoxy coatings are commonly used to protect the interior (and exterior) surfaces of water mains and storage tanks and can be used on the interior surfaces of water pipes in homes, hospitals, hotels, and other buildings. Common major components of epoxies include bisphenols, such as bisphenol A (BPA) or bisphenol F (BPF), and their reactive prepolymers, bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE), respectively. There currently are health concerns about the safety of BPA and BPF due to known estrogenic effects. Determination of key bisphenol leachates, development of a hydrolysis model, and identification of stable hydrolysis products will aid in assessment of human bisphenol exposure through ingestion of drinking water. Liquid chromatography/mass spectrometry (LC/MS/MS) was used for quantitation of key analytes, and a pseudo-first order kinetic approach was used for modeling. In fill-and-dump studies on epoxy-coated pipe specimens, BADGE and a BPA-like compound were identified as leachates. The BADGE hydrolysis model predicts BADGE half-lives at pH 7 and 15, 25, 35, and 40 °C to be 11, 4.6, 2.0, and 1.4 days respectively; the BFDGE half-life was 5 days at pH 7 and 25 °C. The two identified BADGE hydrolysis products are BADGE-H2O and BADGE 2H2O, with BADGE 2H2O being the final end product under the conditions studied. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurement of computed tomography dose profile with pitch variation using Gafchromic XR-QA2 and thermoluminescence dosimeter (TLD)

NASA Astrophysics Data System (ADS)

Purwaningsih, S.; Lubis, L. E.; Pawiro, S. A.; Soejoko, D. S.

2016-03-01

This research was aimed to check the patterns of dose profile on adult and pediatric head scan. We compared measurement result on dose profile along the z- axis rotation at peripheries and center phantom with a variety of pitch, i.e. 0.75, 1, 1.5 for adult and pediatric head protocol, keeping the rest of the scan parameters constant. Measurements were performed on homogeneous, cylindrical PMMA phantom with diameters of 16 and 10 cm using XR-QA2 Gafchromic film and TLD as dosimeters. The measurement result indicated a decrease in the dose about 50% and 47% for adult and pediatric head scan with the increase of pitch. For 0.75 value of pitch adult head scan, dose range for each position were (2.4 - 5.0) cGy, (3.1 - 5.3) cGy, (2.2 - 4.5) cGy, (2.8 - 5.3) cGy, and (3.3 - 5.6) cGy for position of center, 3, 6, 9 and 12 o'clock peripheral phantom position respectively. Dose profile for adult and pediatric head scan protocols has pattern curve with the maximum dose in the middle and tendency of symmetry near the edges, with different the plateau length along z- axis direction in accordance to the measurement position in the phantom.

Laboratory Evaluation of a Colorimetric Hydrazine Dosimeter

DTIC Science & Technology

1990-06-12

4.5 4.5 4 4.3 012 3 3.5 4 3.5 4 4.5 4.5 4.3 59456 014 5 5 5 5.0 5 5.5 5 5.2 014 5.5 6 5 5.5 6 6 6 6.0 GMO COLOR BADGE LOG SHEET TEST 30 1.0. BADGE...3 3.5 3.3 38959 CON .164 0 1.5 1.5 1.5 2 2 2.0 2 2 2.0 2 2 2.0 GMO COLOR BADGE LOG SHEET TEST 84 I.D. BADGE DATE INTER- MMH TIME DOSE RH TEMP POST

A bounding estimate of neutron dose based on measured photon dose around single pass reactors at the Hanford site.

PubMed

Taulbee, Timothy D; Glover, Samuel E; Macievic, Gregory V; Hunacek, Mickey; Smith, Cheryl; DeBord, Gary W; Morris, Donald; Fix, Jack

2010-07-01

Neutron and photon radiation survey records have been used to evaluate and develop a neutron to photon (NP) ratio to reconstruct neutron doses to workers around Hanford's single pass reactors that operated from 1945 to 1972. A total of 5,773 paired neutron and photon measurements extracted from 57 boxes of survey records were used in the development of the NP ratio. The development of the NP ratio enables the use of the recorded dose from an individual's photon dosimeter badge to be used to estimate the unmonitored neutron dose. The Pearson rank correlation between the neutron and photon measurements was 0.71. The NP ratio best fit a lognormal distribution with a geometric mean (GM) of 0.8, a geometric standard deviation (GSD) of 2.95, and the upper 95 th % of this distribution was 4.75. An estimate of the neutron dose based on this NP ratio is considered bounding due to evidence that up to 70% of the total photon exposure received by workers around the single pass reactors occurs during shutdown maintenance and refueling activities when there is no significant neutron exposure. Thus when this NP ratio is applied to the total measured photon dose from an individual film badge dosimeter, the resulting neutron dose is considered bounded.

Radiation dosimeters

DOEpatents

Hoelsher, James W.; Hegland, Joel E.; Braunlich, Peter F.; Tetzlaff, Wolfgang

1992-01-01

Radiation dosimeters and dosimeter badges. The dosimeter badges include first and second parts which are connected to join using a securement to produce a sealed area in which at least one dosimeter is held and protected. The badge parts are separated to expose the dosimeters to a stimulating laser beam used to read dose exposure information therefrom. The badge is constructed to allow automated disassembly and reassembly in a uniquely fitting relationship. An electronic memory is included to provide calibration and identification information used during reading of the dosimeter. Dosimeter mounts which reduce thermal heating requirements are shown. Dosimeter constructions and production methods using thin substrates and phosphor binder-layers applied thereto are also taught.

Adaptive and accelerated tracking-learning-detection

NASA Astrophysics Data System (ADS)

Guo, Pengyu; Li, Xin; Ding, Shaowen; Tian, Zunhua; Zhang, Xiaohu

2013-08-01

An improved online long-term visual tracking algorithm, named adaptive and accelerated TLD (AA-TLD) based on Tracking-Learning-Detection (TLD) which is a novel tracking framework has been introduced in this paper. The improvement focuses on two aspects, one is adaption, which makes the algorithm not dependent on the pre-defined scanning grids by online generating scale space, and the other is efficiency, which uses not only algorithm-level acceleration like scale prediction that employs auto-regression and moving average (ARMA) model to learn the object motion to lessen the detector's searching range and the fixed number of positive and negative samples that ensures a constant retrieving time, but also CPU and GPU parallel technology to achieve hardware acceleration. In addition, in order to obtain a better effect, some TLD's details are redesigned, which uses a weight including both normalized correlation coefficient and scale size to integrate results, and adjusts distance metric thresholds online. A contrastive experiment on success rate, center location error and execution time, is carried out to show a performance and efficiency upgrade over state-of-the-art TLD with partial TLD datasets and Shenzhou IX return capsule image sequences. The algorithm can be used in the field of video surveillance to meet the need of real-time video tracking.

Validation of a smartphone app to map social networks of proximity

PubMed Central

Larsen, Mark E.; Townsend, Samuel; Christensen, Helen

2017-01-01

Social network analysis is a prominent approach to investigate interpersonal relationships. Most studies use self-report data to quantify the connections between participants and construct social networks. In recent years smartphones have been used as an alternative to map networks by assessing the proximity between participants based on Bluetooth and GPS data. While most studies have handed out specially programmed smartphones to study participants, we developed an application for iOS and Android to collect Bluetooth data from participants’ own smartphones. In this study, we compared the networks estimated with the smartphone app to those obtained from sociometric badges and self-report data. Participants (n = 21) installed the app on their phone and wore a sociometric badge during office hours. Proximity data was collected for 4 weeks. A contingency table revealed a significant association between proximity data (ϕ = 0.17, p<0.0001), but the marginal odds were higher for the app (8.6%) than for the badges (1.3%), indicating that dyads were more often detected by the app. We then compared the networks that were estimated using the proximity and self-report data. All three networks were significantly correlated, although the correlation with self-reported data was lower for the app (ρ = 0.25) than for badges (ρ = 0.67). The scanning rates of the app varied considerably between devices and was lower on iOS than on Android. The association between the app and the badges increased when the network was estimated between participants whose app recorded more regularly. These findings suggest that the accuracy of proximity networks can be further improved by reducing missing data and restricting the interpersonal distance at which interactions are detected. PMID:29261782

Radiation damage and sensitization effects on thermoluminescence of LiF:Mg,Ti (TLD-700)

NASA Astrophysics Data System (ADS)

Farag, M. A.; Sadek, A. M.; Shousha, Hany. A.; El-Hagg, A. A.; Atta, M. R.; Kitis, G.

2017-09-01

The radiation damage effects and enhancement the thermoluminescence (TL) efficiency of LiF:Mg,Ti (TLD-700)dosimeters via sensitization method were discussed. Attempts to eliminate the effects of damage and sensitization were made using different types of annealing processes. The results showed that after irradiating the dosimeters with dose > 250 Gy of 60Co gamma source, damage effects were observed. The sensitivity of the total area under the curve was decreased by a factor of ∼0.5 after irradiation at a pre-test dose of 2 kGy. However, the effects of radiation damage on each glow-peak are different. The glow-peak 2 was the only peak that was not affected by the high-dose irradiation. It has been shown that the degree of the radiation damage effect is related to the maximum dose-response function, f(D)max of the glow-peak. In general, significant radiation damage effects were observed for the glow-peaks of high f(D)max . Post-irradiation anneal at 280 °C for 30 min causes dramatic effects on the shape of the glow-curve and as well as on the sensitivity of the dosimeters. An increasing by a factor of ∼35 in the sensitivity of the total area under the curve was observed at a pre-test dose of 2 kGy. Improving the sensitivity of peak 7 by a factor of∼22 was the dominant factor in increasing the sensitivity of the dosimeters. On the other hand, an increasing by factors of ∼2.5 and ∼4 was found for peaks 2 and 5 respectively. On the other hand, a decreasing by a factor ∼0.5 was observed for peaks 3 and 4. At pre-test dose levels >250 Gy, a very strange and high intensity tail was observed in the high-temperature region of the glow-curves. The readout anneal was not enough to remove this tail. While, the furnace anneal could eliminate the sensitization effects but not the radiation damage effects on the sensitivity of the dosimeters.

In vivo thermoluminescence dosimetry for total body irradiation.

PubMed

Palkosková, P; Hlavata, H; Dvorák, P; Novotný, J; Novotný, J

2002-01-01

An improvement in the clinical results obtained using total body irradiation (TBI) with photon beams requires precise TBI treatment planning, reproducible irradiation, precise in vivo dosimetry, accurate documentation and careful evaluation. In vivo dosimetry using LiF Harshaw TLD-100 chips was used during the TBI treatments performed in our department. The results of in vivo thermoluminescence dosimetry (TLD) show that using TLD measurements and interactive adjustment of some treatment parameters based on these measurements, like monitor unit calculations, lung shielding thickness and patient positioning, it is possible to achieve high precision in absorbed dose delivery (less than 0.5%) as well as in homogeneity of irradiation (less than 6%).

Donating Peripheral Blood Stem Cells

MedlinePlus

... Badges Translated badges Sign up for Email Updates Shop Support the Cause Jeff, donor The cure for ... a community transplanting hope. Give . Join . Volunteer . Learn . Shop Careers Working with us Career opportunities Employee benefits ...

Feasibility study of glass dosimeter postal dosimetry audit of high-energy radiotherapy photon beams.

PubMed

Mizuno, Hideyuki; Kanai, Tatsuaki; Kusano, Yohsuke; Ko, Susumu; Ono, Mari; Fukumura, Akifumi; Abe, Kyoko; Nishizawa, Kanae; Shimbo, Munefumi; Sakata, Suoh; Ishikura, Satoshi; Ikeda, Hiroshi

2008-02-01

The characteristics of a glass dosimeter were investigated for its potential use as a tool for postal dose audits. Reproducibility, energy dependence, field size and depth dependence were compared to those of a thermoluminescence dosimeter (TLD), which has been the major tool for postal dose audits worldwide. A glass dosimeter, GD-302M (Asahi Techno Glass Co.) and a TLD, TLD-100 chip (Harshaw Co.) were irradiated with gamma-rays from a (60)Co unit and X-rays from a medical linear accelerator (4, 6, 10 and 20 MV). The dosimetric characteristics of the glass dosimeter were almost equivalent to those of the TLD, in terms of utility for dosimetry under the reference condition, which is a 10 x 10 cm(2) field and 10 cm depth. Because of its reduced fading, compared to the TLD, and easy quality control with the ID number, the glass dosimeter proved to be a suitable tool for postal dose audits. Then, we conducted postal dose surveys of over 100 facilities and got good agreement, with a standard deviation of about 1.3%. Based on this study, postal dose audits throughout Japan will be carried out using a glass dosimeter.

Dosimetry around metallic ports in tissue expanders in patients receiving postmastectomy radiation therapy: an ex vivo evaluation.

PubMed

Moni, Janaki; Graves-Ditman, Maria; Cederna, Paul; Griffith, Kent; Krueger, Editha A; Fraass, Benedick A; Pierce, Lori J

2004-01-01

Postmastectomy breast reconstruction can be accomplished utilizing tissue expanders and implants. However, in patients who require postoperative radiotherapy, the complication rate with tissue expander/implant reconstruction can exceed 50%. One potential cause of this high complication rate may be the metallic port in the tissue expander producing altered dosimetry in the region of the metallic device. The purpose of this study was to quantify the radiation dose distribution in the vicinity of the metallic port and determine its potential contribution to this extremely high complication rate. The absolute dosimetric effect of the tissue expander's metallic port was quantified using film and thermoluminescent dosimetry (TLD) studies with a single beam incident on a metallic port extracted from an expander. TLD measurements were performed at 11 reproducible positions on an intact expander irradiated with tangential fields. A computed tomography (CT)-based treatment plan without inhomogeneity corrections was used to derive expected doses for all TLD positions. Multiple irradiation experiments were performed for all TLD data. Confidence intervals for the dose at TLD sites with the metallic port in place were compared to the expected dose at the site without the metallic port. Film studies did not reveal a significant component of scatter around the metallic port. TLD studies of the extracted metallic port revealed highest doses within the casing of the metallic port and no consistent increased dose at the surface of the expander. No excess dose due to the metallic port in the expander was noted with the phantom TLD data. Based upon these results, it does not appear that the metallic port in tissue expanders significantly contributes to the high complication rate experienced in patients undergoing tissue expander breast reconstruction and receiving radiation therapy. Strategies designed to reduce the breast reconstruction complication rate in this clinical setting will

A global lightning parameterization based on statistical relationships among environmental factors, aerosols, and convective clouds in the TRMM climatology

NASA Astrophysics Data System (ADS)

Stolz, Douglas C.; Rutledge, Steven A.; Pierce, Jeffrey R.; van den Heever, Susan C.

2017-07-01

The objective of this study is to determine the relative contributions of normalized convective available potential energy (NCAPE), cloud condensation nuclei (CCN) concentrations, warm cloud depth (WCD), vertical wind shear (SHEAR), and environmental relative humidity (RH) to the variability of lightning and radar reflectivity within convective features (CFs) observed by the Tropical Rainfall Measuring Mission (TRMM) satellite. Our approach incorporates multidimensional binned representations of observations of CFs and modeled thermodynamics, kinematics, and CCN as inputs to develop approximations for total lightning density (TLD) and the average height of 30 dBZ radar reflectivity (AVGHT30). The results suggest that TLD and AVGHT30 increase with increasing NCAPE, increasing CCN, decreasing WCD, increasing SHEAR, and decreasing RH. Multiple-linear approximations for lightning and radar quantities using the aforementioned predictors account for significant portions of the variance in the binned data set (R2 ≈ 0.69-0.81). The standardized weights attributed to CCN, NCAPE, and WCD are largest, the standardized weight of RH varies relative to other predictors, while the standardized weight for SHEAR is comparatively small. We investigate these statistical relationships for collections of CFs within various geographic areas and compare the aerosol (CCN) and thermodynamic (NCAPE and WCD) contributions to variations in the CF population in a partial sensitivity analysis based on multiple-linear regression approximations computed herein. A global lightning parameterization is developed; the average difference between predicted and observed TLD decreases from +21.6 to +11.6% when using a hybrid approach to combine separate approximations over continents and oceans, thus highlighting the need for regionally targeted investigations in the future.

Impact of a smoking ban in hospitality venues on second hand smoke exposure: a comparison of exposure assessment methods

PubMed Central

2013-01-01

Background In May 2010, Switzerland introduced a heterogeneous smoking ban in the hospitality sector. While the law leaves room for exceptions in some cantons, it is comprehensive in others. This longitudinal study uses different measurement methods to examine airborne nicotine levels in hospitality venues and the level of personal exposure of non-smoking hospitality workers before and after implementation of the law. Methods Personal exposure to second hand smoke (SHS) was measured by three different methods. We compared a passive sampler called MoNIC (Monitor of NICotine) badge, to salivary cotinine and nicotine concentration as well as questionnaire data. Badges allowed the number of passively smoked cigarettes to be estimated. They were placed at the venues as well as distributed to the participants for personal measurements. To assess personal exposure at work, a time-weighted average of the workplace badge measurements was calculated. Results Prior to the ban, smoke-exposed hospitality venues yielded a mean badge value of 4.48 (95%-CI: 3.7 to 5.25; n = 214) cigarette equivalents/day. At follow-up, measurements in venues that had implemented a smoking ban significantly declined to an average of 0.31 (0.17 to 0.45; n = 37) (p = 0.001). Personal badge measurements also significantly decreased from an average of 2.18 (1.31-3.05 n = 53) to 0.25 (0.13-0.36; n = 41) (p = 0.001). Spearman rank correlations between badge exposure measures and salivary measures were small to moderate (0.3 at maximum). Conclusions Nicotine levels significantly decreased in all types of hospitality venues after implementation of the smoking ban. In-depth analyses demonstrated that a time-weighted average of the workplace badge measurements represented typical personal SHS exposure at work more reliably than personal exposure measures such as salivary cotinine and nicotine. PMID:23731820

Impact of a smoking ban in hospitality venues on second hand smoke exposure: a comparison of exposure assessment methods.

PubMed

Rajkumar, Sarah; Huynh, Cong Khanh; Bauer, Georg F; Hoffmann, Susanne; Röösli, Martin

2013-06-04

In May 2010, Switzerland introduced a heterogeneous smoking ban in the hospitality sector. While the law leaves room for exceptions in some cantons, it is comprehensive in others. This longitudinal study uses different measurement methods to examine airborne nicotine levels in hospitality venues and the level of personal exposure of non-smoking hospitality workers before and after implementation of the law. Personal exposure to second hand smoke (SHS) was measured by three different methods. We compared a passive sampler called MoNIC (Monitor of NICotine) badge, to salivary cotinine and nicotine concentration as well as questionnaire data. Badges allowed the number of passively smoked cigarettes to be estimated. They were placed at the venues as well as distributed to the participants for personal measurements. To assess personal exposure at work, a time-weighted average of the workplace badge measurements was calculated. Prior to the ban, smoke-exposed hospitality venues yielded a mean badge value of 4.48 (95%-CI: 3.7 to 5.25; n = 214) cigarette equivalents/day. At follow-up, measurements in venues that had implemented a smoking ban significantly declined to an average of 0.31 (0.17 to 0.45; n = 37) (p = 0.001). Personal badge measurements also significantly decreased from an average of 2.18 (1.31-3.05 n = 53) to 0.25 (0.13-0.36; n = 41) (p = 0.001). Spearman rank correlations between badge exposure measures and salivary measures were small to moderate (0.3 at maximum). Nicotine levels significantly decreased in all types of hospitality venues after implementation of the smoking ban. In-depth analyses demonstrated that a time-weighted average of the workplace badge measurements represented typical personal SHS exposure at work more reliably than personal exposure measures such as salivary cotinine and nicotine.

Pilot evaluation of isolation patients' perceptions on ability to identify types of health care workers when wearing isolation gowns.

PubMed

Roderick, Mickey; Speroni, Karen Gabel; Stafford, Amy; Seibert, Dorothy J

2017-03-01

In a survey research study, perceptions of 50 hospitalized patients on contact isolation were evaluated regarding their ability to identify health care worker (HCW) type in isolation gowns with no hospital badge under or on the gown, in isolation gowns with the hospital badge partially visible through the gown, and in isolation gowns with a preprinted large font Registered Nurse and Nursing Technician sticker badge on the outside of the gown. Patients ranked their ability to identify HCWs when entering their hospital room as important (average ranking, 8.0, where 0 was not at all important and 10 was very important); 28 patients (56%) specified all HCWs entering their hospital room should wear a preprinted large font sticker badge on the outside of their isolation gowns. Patients found little difficulty identifying HCW type with the large font preprinted sticker badge (average difficulty ranking, 1.0, where 0 is not at all difficult and 10 is very difficult), a simplistic method to improve HCW type identification. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Inhaled corticosteroid metered-dose inhalers: how do variations in technique for solutions versus suspensions affect drug distribution?

PubMed

Robinson, Christie A; Tsourounis, Candy

2013-03-01

To assess the literature that evaluates how variations in metered-dose inhaler (MDI) technique affect lung distribution for inhaled corticosteroids (ICSs) formulated as MDI suspensions and solutions. PubMed (up to November 2012) and Cochrane Library (up to November 2012) were searched using the terms metered-dose inhalers, HFA 134a, Asthma/*drug therapy, and inhaled corticosteroids. In addition, reference citations from publications identified were reviewed. All articles in English from the data sources that assessed MDI technique comparing total lung distribution (TLD) of MDI solutions or suspensions formulated with ICSs were included in the review. Five relevant studies were identified. Five controlled studies compared how variations in MDI technique affect TLD for ICS MDI solutions with suspensions. MDI solutions resulted in greater TLD compared with larger particle MDI suspensions. Delayed or early inspiration upon device actuation of MDI solutions resulted in less TLD than coordinated actuation, but with a 3- to 4-times greater TLD than MDI suspensions inhaled using a standard technique. A sixth study evaluated inspiratory flow rates (IFR) for small, medium, and large particles. Rapid and slow IFRs resulted in similar TLD for small particles, while far fewer particles reached the airways with medium and large particles at rapid, rather than slow, IFRs. Based on the literature evaluated, standard MDI technique should be used for ICS suspensions. ICS MDI solutions can provide a higher average TLD than larger-particle ICS suspensions using standard technique, discoordinated inspiration and medication actuation timing, or rapid and slow IFRs. ICS MDI solutions allow for a more forgiving technique, which makes them uniquely suitable options for patients with asthma who have difficultly with MDI technique.

Badging, Real ID

Science.gov Websites

. REAL ID LANL Impacts and Solutions The federal government has determined New Mexico is non-compliant Identification Cards whom will also become Non-Compliant. Access through LANL Vehicle Access Portals unaffected alternate ID if they are coming from "non-compliant" REAL-ID states LANS and the Field Office have

An overview of game-based learning in building services engineering education

NASA Astrophysics Data System (ADS)

Alanne, Kari

2016-03-01

To ensure proper competence development and short graduation times for engineering students, it is essential that the study motivation is encouraged by new learning methods. In game-based learning, the learner's engagement is increased and learning is made meaningful by applying game-like features such as competition and rewarding through virtual promotions or achievement badges. In this paper, the state of the art of game-based learning in building services engineering education at university level is reviewed and discussed. A systematic literature review indicates that educational games have been reported in the field of related disciplines, such as mechanical and civil engineering. The development of system-level educational games that realistically simulate work life in building services engineering is still in its infancy. Novel rewarding practices and more comprehensive approaches entailing the state-of-the-art information tools such as building information modelling, geographic information systems, building management systems and augmented reality are needed in the future.

32 CFR 507.6 - Authority to manufacture.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 3 2010-07-01 2010-07-01 true Authority to manufacture. 507.6 Section 507.6... PUBLIC RELATIONS MANUFACTURE AND SALE OF DECORATIONS, MEDALS, BADGES, INSIGNIA, COMMERCIAL USE OF HERALDIC DESIGNS AND HERALDIC QUALITY CONTROL PROGRAM Manufacture and Sale of Decorations, Medals, Badges...

Occupational dose in interventional radiology procedures.

PubMed

Chida, Koichi; Kaga, Yuji; Haga, Yoshihiro; Kataoka, Nozomi; Kumasaka, Eriko; Meguro, Taiichiro; Zuguchi, Masayuki

2013-01-01

Interventional radiology tends to involve long procedures (i.e., long fluoroscopic times). Therefore, radiation protection for interventional radiology staff is an important issue. This study describes the occupational radiation dose for interventional radiology staff, especially nurses, to clarify the present annual dose level for interventional radiology nurses. We compared the annual occupational dose (effective dose and dose equivalent) among interventional radiology staff in a hospital where 6606 catheterization procedures are performed annually. The annual occupational doses of 18 physicians, seven nurses, and eight radiologic technologists were recorded using two monitoring badges, one worn over and one under their lead aprons. The annual mean ± SD effective dose (range) to the physicians, nurses, and radiologic technologists using two badges was 3.00 ± 1.50 (0.84-6.17), 1.34 ± 0.55 (0.70-2.20), and 0.60 ± 0.48 (0.02-1.43) mSv/y, respectively. Similarly, the annual mean ± SD dose equivalent range was 19.84 ± 12.45 (7.0-48.5), 4.73 ± 0.72 (3.9-6.2), and 1.30 ± 1.00 (0.2-2.7) mSv/y, respectively. The mean ± SD effective dose for the physicians was 1.02 ± 0.74 and 3.00 ± 1.50 mSv/y for the one- and two-badge methods, respectively (p < 0.001). Similarly, the mean ± SD effective dose for the nurses (p = 0.186) and radiologic technologists (p = 0.726) tended to be lower using the one-badge method. The annual occupational dose for interventional radiology staff was in the order physicians > nurses > radiologic technologists. The occupational dose determined using one badge under the apron was far lower than the dose obtained with two badges in both physicians and nonphysicians. To evaluate the occupational dose correctly, we recommend use of two monitoring badges to evaluate interventional radiology nurses as well as physicians.

Thymineless death is inhibited by CsrA in Escherichia coli lacking the SOS response.

PubMed

Hamilton, Holly M; Wilson, Ray; Blythe, Martin; Nehring, Ralf B; Fonville, Natalie C; Louis, Edward J; Rosenberg, Susan M

2013-11-01

Thymineless death (TLD) is the rapid loss of colony-forming ability in bacterial, yeast and human cells starved for thymine, and is the mechanism of action of common chemotherapeutic drugs. In Escherichia coli, significant loss of viability during TLD requires the SOS replication-stress/DNA-damage response, specifically its role in inducing the inhibitor of cell division, SulA. An independent RecQ- and RecJ-dependent TLD pathway accounts for a similarly large additional component of TLD, and a third SOS- and RecQ/J-independent TLD pathway has also been observed. Although two groups have implicated the SOS-response in TLD, an SOS-deficient mutant strain from an earlier study was found to be sensitive to thymine deprivation. We performed whole-genome resequencing on that SOS-deficient strain and find that, compared with the SOS-proficient control strain, it contains five mutations in addition to the SOS-blocking lexA(Ind(-)) mutation. One of the additional mutations, csrA, confers TLD sensitivity specifically in SOS-defective strains. We find that CsrA, a carbon storage regulator, reduces TLD in SOS- or SulA-defective cells, and that the increased TLD that occurs in csrA(-) SOS-defective cells is dependent on RecQ. We consider a hypothesis in which the modulation of nucleotide pools by CsrA might inhibit TLD specifically in SOS-deficient (SulA-deficient) cells. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluating Boy Scout Geology Education, A Pilot Study

NASA Astrophysics Data System (ADS)

Hintz, R. S.; Thomson, B.

2008-12-01

This study investigated geology knowledge acquisition by Boy Scouts through use of the Boy Scout Geology Merit Handbook. In this study, boys engaged in hands-on interactive learning following the requirements set forth in the Geology Merit Badge Handbook. The purposes of this study were to determine the amount of geology content knowledge engendered in adolescent males through the use of the Geology Merit Badge Handbook published by the Boy Scouts of America; to determine if single sex, activity oriented, free-choice learning programs can be effective in promoting knowledge development in young males; and to determine if boys participating in the Scouting program believed their participation helped them succeed in school. Members of a local Boy Scout Troop between the ages of 11 and 18 were invited to participate in a Geology Merit Badge program. Boys who did not already possess the badge were allowed to self-select participation. The boys' content knowledge of geology, rocks, and minerals was pre- and post-tested. Boys were interviewed about their school and Scouting experiences; whether they believed their Scouting experiences and work in Merit Badges contributed to their success in school. Contributing educational theories included single-sex education, informal education with free-choice learning, learning styles, hands-on activities, and the social cognitive theory concept of self-efficacy. Boys who completed this study seemed to possess a greater knowledge of geology than they obtained in school. If boys who complete the Boy Scout Geology Merit Badge receive additional geological training, their field experiences and knowledge acquired through this learning experience will be beneficial, and a basis for continued scaffolding of geologic knowledge.

75 FR 39500 - Privacy Act of 1974; System of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-09

... with ``Badge and vehicle control records that at a minimum include; name, Social Security Number (SSN... system: Badge and vehicle control records that at a minimum include; name, Social Security Number (SSN... maintenance of the system: 10 U.S.C. 8013, Secretary of the Air Force, Powers and Duties; Department of...

Evaluation of Sloped Bottom Tuned Liquid Damper for Reduction of Seismic Response of Tall Buildings

NASA Astrophysics Data System (ADS)

Patil, G. R.; Singh, K. D.

2016-12-01

Due to migration of people to urban area, high land costs and use of light weight materials modern buildings tend to be taller, lighter and flexible. These buildings possess low damping. This increases the possibility of failure during earthquake ground motion and also affect the serviceability during wind vibrations. Out of many available techniques today, to reduce the response of structure under dynamic loading, Tuned Liquid Damper (TLD) is a recent technique to mitigate seismic response. However TLD has been used to mitigate the wind induced structural vibrations. Flat bottom TLD gives energy back to the structure after event of dynamic loading and it is termed as beating. Beating affects the performance of TLD. Study attempts to analyze the effectiveness of sloped bottom TLD for reducing seismic vibrations of structure. Concept of equivalent flat bottom LD has been used to analyze sloped bottom TLD. Finite element method (EM) is used to model the structure and the liquid in the TLD. MATLAB code is developed to study the response of structure, the liquid sloshing in the tank and the coupled fluid-structure interaction. A ten storey two bay RC frame is analyzed for few inputs of ground motion. A sinusoidal ground motion corresponding to resonance condition with fundamental frequency of frame is analyzed. In the analysis the inherent damping of structure is not considered. Observations from the study shows that sloped bottom TLD uses less amount of liquid than flat bottom TLD. Also observed that efficiency of sloped bottom TLD can be improved if it is properly tuned.

Improving Critical Thinking Using a Web-Based Tutorial Environment.

PubMed

Wiesner, Stephen M; Walker, J D; Creeger, Craig R

2017-01-01

With a broad range of subject matter, students often struggle recognizing relationships between content in different subject areas. A scenario-based learning environment (SaBLE) has been developed to enhancing clinical reasoning and critical thinking among undergraduate students in a medical laboratory science program and help them integrate their new knowledge. SaBLE incorporates aspects of both cognitive theory and instructional design, including reduction of extraneous cognitive load, goal-based learning, feedback timing, and game theory. SaBLE is a website application that runs in most browsers and devices, and is used to develop randomly selected scenarios that challenge user thinking in almost any scenario-based instruction. User progress is recorded to allow comprehensive data analysis of changes in user performance. Participation is incentivized using a point system and digital badges or awards. SaBLE was deployed in one course with a total exposure for the treatment group of approximately 9 weeks. When assessing performance of SaBLE participants, and controlling for grade point average as a possible confounding variable, there was a statistically significant correlation between the number of SaBLE levels completed and performance on selected critical-thinking exam questions addressing unrelated content.

77 FR 1758 - Self-Regulatory Organizations; NYSE Amex LLC; Notice of Filing and Immediate Effectiveness of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-11

... Amending its Price List To Eliminate the Clerk Badge Fee and the e-Broker Hand Held Device Fee January 5... of the Proposed Rule Change The Exchange proposes to amend its Price List to eliminate the Clerk... Proposed Rule Change 1. Purpose The Exchange proposes to amend its Price List to eliminate the Clerk Badge...

Geoscience Education in the Boy Scouts of America

ERIC Educational Resources Information Center

Hintz, Rachel; Thomson, Barbara

2012-01-01

Boy Scout geoscience education is not "desk" education--it is an informal, hands-on, real-world education where Scouts learn through activities, trips, and the outdoors, as well as in meetings and in the merit badge program. Merit badge requirements, many of which meet National Science Education Standards for Earth and Space Science,…

Preferences of Iranian patients about style of labelling and calling of their physicians.

PubMed

Najafi, Mostafa; Khoshdel, Abolfazl; Kheiri, Soleiman

2012-07-01

To document the performance of patients regarding label styles of their doctors and modes of addressing them. In this descriptive survey, 400 patients, at two teaching hospitals--Hajar and Kashani--with a mean age of 40.5 +/- 19.5 years were enrolled. Their demographic data, disorder type and duration were recorded. Photos demonstrating different label and attire styles based on Iranian culture were shown to the patients and they were asked to mark their performances about the necessity of wearing name badge. They were also requested to nominate the way they preferred to be addressed by the doctors. Of the participants, 180 (45%) were men; 307 (76.8%) were married; and the mean duration of hospitalisation was 2.5 +/- 2.1 days. Most of the patients, (n = 320; 80%) stated that the doctor should always wear a name badge; 301 (75.3%) preferred to call their physicians by title; and 227 (56.8%) preferred to be called by their surnames. Patients preferred to have female physicians wearing white coat, shirt and trousers as the preferred dress code. Patients in the study preferred to have the physicians professionally attired, with the only difference being the dark veil for female physicians. Name badge and white coat were also preferred by the patients.

On the experimental validation of model-based dose calculation algorithms for 192Ir HDR brachytherapy treatment planning

NASA Astrophysics Data System (ADS)

Pappas, Eleftherios P.; Zoros, Emmanouil; Moutsatsos, Argyris; Peppa, Vasiliki; Zourari, Kyveli; Karaiskos, Pantelis; Papagiannis, Panagiotis

2017-05-01

There is an acknowledged need for the design and implementation of physical phantoms appropriate for the experimental validation of model-based dose calculation algorithms (MBDCA) introduced recently in 192Ir brachytherapy treatment planning systems (TPS), and this work investigates whether it can be met. A PMMA phantom was prepared to accommodate material inhomogeneities (air and Teflon), four plastic brachytherapy catheters, as well as 84 LiF TLD dosimeters (MTS-100M 1  ×  1  ×  1 mm3 microcubes), two radiochromic films (Gafchromic EBT3) and a plastic 3D dosimeter (PRESAGE). An irradiation plan consisting of 53 source dwell positions was prepared on phantom CT images using a commercially available TPS and taking into account the calibration dose range of each detector. Irradiation was performed using an 192Ir high dose rate (HDR) source. Dose to medium in medium, Dmm , was calculated using the MBDCA option of the same TPS as well as Monte Carlo (MC) simulation with the MCNP code and a benchmarked methodology. Measured and calculated dose distributions were spatially registered and compared. The total standard (k  =  1) spatial uncertainties for TLD, film and PRESAGE were: 0.71, 1.58 and 2.55 mm. Corresponding percentage total dosimetric uncertainties were: 5.4-6.4, 2.5-6.4 and 4.85, owing mainly to the absorbed dose sensitivity correction and the relative energy dependence correction (position dependent) for TLD, the film sensitivity calibration (dose dependent) and the dependencies of PRESAGE sensitivity. Results imply a LiF over-response due to a relative intrinsic energy dependence between 192Ir and megavoltage calibration energies, and a dose rate dependence of PRESAGE sensitivity at low dose rates (<1 Gy min-1). Calculations were experimentally validated within uncertainties except for MBDCA results for points in the phantom periphery and dose levels  <20%. Experimental MBDCA validation is laborious, yet feasible. Further

Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for 125I and 103Pd brachytherapy sources relative to 60Co.

PubMed

Reed, J L; Rasmussen, B E; Davis, S D; Micka, J A; Culberson, W S; DeWerd, L A

2014-12-01

To determine the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters (TLD-100) for (125)I and (103)Pd brachytherapy sources relative to (60)Co. LiF:Mg,Ti TLDs were irradiated with low-energy brachytherapy sources and with a (60)Co teletherapy source. The brachytherapy sources measured were the Best 2301 (125)I seed, the OncoSeed 6711 (125)I seed, and the Best 2335 (103)Pd seed. The TLD light output per measured air-kerma strength was determined for the brachytherapy source irradiations, and the TLD light output per air kerma was determined for the (60)Co irradiations. Monte Carlo (MC) simulations were used to calculate the dose-to-TLD rate per air-kerma strength for the brachytherapy source irradiations and the dose to TLD per air kerma for the (60)Co irradiations. The measured and MC-calculated results for all irradiations were used to determine the TLD intrinsic energy dependence for (125)I and (103)Pd relative to (60)Co. The relative TLD intrinsic energy dependences (relative to (60)Co) and associated uncertainties (k = 1) were determined to be 0.883 ± 1.3%, 0.870 ± 1.4%, and 0.871 ± 1.5% for the Best 2301 seed, OncoSeed 6711 seed, and Best 2335 seed, respectively. The intrinsic energy dependence of TLD-100 is dependent on photon energy, exhibiting changes of 13%-15% for (125)I and (103)Pd sources relative to (60)Co. TLD measurements of absolute dose around (125)I and (103)Pd brachytherapy sources should explicitly account for the relative TLD intrinsic energy dependence in order to improve dosimetric accuracy.

Nonuniform Irradiation of the Canine Intestine. 2. Dosimetry

DTIC Science & Technology

1990-01-01

irradiation is accurate assessment In vivo dosimetry was done using Harshaw (Solon, Ohio) TLD - 100 lith- of the injury after either accidental or... vivo TLD dosimetry system allowed measure- 5 and 6. The dose was determined from the median TLD ment of the °Co dose deposited in the canine small...provide replicate measurements. Two separate dosimetry tubes were deveoped (Fig. 1). The first contained 30 TLD cap- doses (1). Nevertheless, current

MO-A-BRB-01: TG191: Clinical Use of Luminescent Dosimeters

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

Kry, S.

This presentation will highlight the upcoming TG-191 report: Clinical Use of Luminescent Dosimeters. Luminescent dosimetry based on TLD and OSLD is a practical, accurate, and precise technique for point dosimetry in medical physics applications. The charges of Task Group 191 were to detail the methodologies for practical and optimal luminescent dosimetry in a clinical setting. This includes (1) To review the variety of TLD/OSL materials available, including features and limitations of each. (2) To outline the optimal steps to achieve accurate and precise dosimetry with luminescent detectors and to evaluate the uncertainty induced when less rigorous procedures are used. (3)more » To develop consensus guidelines on the optimal use of luminescent dosimeters for clinical practice. (4) To develop guidelines for special medically relevant uses of TLDs/OSLs (e.g., mixed field i.e. photon/neutron dosimetry, particle beam dosimetry, skin dosimetry). While this report provides general guidelines for arbitrary TLD and OSLD processes, the report, and therefore this presentation, provide specific guidance for TLD-100 (LiF:Ti,Mg) and nanoDot (Al2O3:C) dosimeters because of their prevalence in clinical practice. Learning Objectives: Understand the available dosimetry systems, and basic theory of their operation Understand the range of dose determination methodologies and the uncertainties associated with them Become familiar with special considerations for TLD/OSLD relevant for special clinical situations Learn recommended commissioning and QA procedures for these dosimetry systems.« less

MO-A-BRB-00: TG191: Clinical Use of Luminescent Dosimeters

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

NONE

This presentation will highlight the upcoming TG-191 report: Clinical Use of Luminescent Dosimeters. Luminescent dosimetry based on TLD and OSLD is a practical, accurate, and precise technique for point dosimetry in medical physics applications. The charges of Task Group 191 were to detail the methodologies for practical and optimal luminescent dosimetry in a clinical setting. This includes (1) To review the variety of TLD/OSL materials available, including features and limitations of each. (2) To outline the optimal steps to achieve accurate and precise dosimetry with luminescent detectors and to evaluate the uncertainty induced when less rigorous procedures are used. (3)more » To develop consensus guidelines on the optimal use of luminescent dosimeters for clinical practice. (4) To develop guidelines for special medically relevant uses of TLDs/OSLs (e.g., mixed field i.e. photon/neutron dosimetry, particle beam dosimetry, skin dosimetry). While this report provides general guidelines for arbitrary TLD and OSLD processes, the report, and therefore this presentation, provide specific guidance for TLD-100 (LiF:Ti,Mg) and nanoDot (Al2O3:C) dosimeters because of their prevalence in clinical practice. Learning Objectives: Understand the available dosimetry systems, and basic theory of their operation Understand the range of dose determination methodologies and the uncertainties associated with them Become familiar with special considerations for TLD/OSLD relevant for special clinical situations Learn recommended commissioning and QA procedures for these dosimetry systems.« less

Whole-body dose and energy measurements in radiotherapy by a combination of LiF:Mg,Cu,P and LiF:Mg,Ti.

PubMed

Hauri, Pascal; Schneider, Uwe

2018-04-01

Long-term survivors of cancer who were treated with radiotherapy are at risk of a radiation-induced tumor. Hence, it is important to model the out-of-field dose resulting from a cancer treatment. These models have to be verified with measurements, due to the small size, the high sensitivity to ionizing radiation and the tissue-equivalent composition, LiF thermoluminescence dosimeters (TLD) are well-suited for out-of-field dose measurements. However, the photon energy variation of the stray dose leads to systematic dose errors caused by the variation in response with radiation energy of the TLDs. We present a dosimeter which automatically corrects for the energy variation of the measured photons by combining LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) chips. The response with radiation energy of TLD100 and TLD100H compared to 60 Co was taken from the literature. For the measurement, a TLD100H was placed on top of a TLD100 chip. The dose ratio between the TLD100 and TLD100H, combined with the ratio of the response curves was used to determine the mean energy. With the energy, the individual correction factors for TLD100 and TLD100H could be found. The accuracy in determining the in- and out-of-field dose for a nominal beam energy of 6MV using the double-TLD unit was evaluated by an end-to-end measurement. Furthermore, published Monte Carlo (M.C.) simulations of the mean photon energy for brachytherapy sources, stray radiation of a treatment machine and cone beam CT (CBCT) were compared to the measured mean energies. Finally, the photon energy distribution in an Alderson phantom was measured for different treatment techniques applied with a linear accelerator. Additionally, a treatment plan was measured with a cobalt machine combined with an MRI. For external radiotherapy, the presented double-TLD unit showed a relative type A uncertainty in doses of -1%±2% at the two standard deviation level compared to an ionization chamber. The type A uncertainty in dose was in

SU-E-T-112: Experimental Characterization of a Novel Thermal Reservoir for Consistent and Accurate Annealing of High-Sensitivity TLDs.

PubMed

Donahue, W; Bongiorni, P; Hearn, R; Rodgers, J; Nath, R; Chen, Z

2012-06-01

To develop and characterize a novel thermal reservoir for consistent and accurate annealing of high-sensitivity thermoluminescence dosimeters (TLD-100H) for dosimetry of brachytherapy sources. The sensitivity of TLD-100H is about 18 times that of TLD-100 which has clear advantages in for interstitial brachytherapy sources. However, the TLD-100H requires a short high temperature annealing cycle (15 min.) and opening and closing the oven door causes significant temperature fluctuations leading to unreliable measurements. A new thermal reservoir made of aluminum alloy was developed to provide stable temperature environment in a standard hot air oven. The thermal reservoir consisted of a 20 cm × 20 cm × 8 cm Al block with a machine-milled chamber in the middle to house the aluminum TLD holding tray. The thermal reservoir was placed inside the oven until it reaches thermal equilibrium with oven chamber. The temperatures of the oven chamber, heat reservoir, and TLD holding tray were monitored by two independent thermo-couples which interfaced digitally to a control computer. A LabView interface was written for monitoring and recording the temperatures in TLD holding tray, the thermal reservoir, and oven chamber. The temperature profiles were measured as a function of oven-door open duration. The settings for oven chamber temperature and oven door open-close duration were optimized to achieve a stable temperature of 240 0C in the TLD holding tray. Complete temperature profiles of the TLD annealing tray over the entire annealing process were obtained. A LabView interface was written for monitoring and recording the temperatures in TLD holding The use of the thermal reservoir has significantly reduced the temperature fluctuations caused by the opening of oven door when inserting the TLD holding tray into the oven chamber. It has enabled consistent annealing of high-sensitivity TLDs. A comprehensive characterization of a custom-built novel thermal reservoir for annealing

SU-G-201-08: Energy Response of Thermoluminescent Microcube Dosimeters in Water for Kilovoltage X-Ray Beams

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

Di Maso, L; Lawless, M; Culberson, W

Purpose: To characterize the energy dependence for TLD-100 microcubes in water at kilovoltage energies. Methods: TLD-100 microcubes with dimensions of (1 × 1 × 1) mm{sup 3} were irradiated with kilovoltage x-rays in a custom-built thin-window liquid water phantom. The TLD-100 microcubes were held in Virtual Water™ probes and aligned at a 2 cm depth in water. Irradiations were performed using the M-series x-ray beams of energies ranging from 50-250 kVp and normalized to a {sup 60}Co beam located at the UWADCL. Simulations using the EGSnrc Monte Carlo Code System were performed to model the x-ray beams, the {sup 60}Comore » beam, the water phantom and the dosimeters in the phantom. The egs-chamber user code was used to tally the dose to the TLDs and the dose to water. The measurements and calculations were used to determine the intrinsic energy dependence, absorbed-dose energy dependence, and absorbed-dose sensitivity. These values were compared to TLD-100 chips with dimensions of (3.2 × 0.9 × 0.9) mm{sup 3}. Results: The measured TLD-100 microcube response per dose to water among all investigated x-ray energies had a maximum percent difference of 61% relative to {sup 60}Co. The simulated ratio of dose to water to the dose to TLD had a maximum percent difference of 29% relative to {sup 60}Co. The ratio of dose to TLD to the TLD output had a maximum percent difference of 13% relative to {sup 60}Co. The maximum percent difference for the absorbed-dose sensitivity was 15% more than the used value of 1.41. Conclusion: These results confirm that differences in beam quality have a significant effect on TLD response when irradiated in water. These results also indicated a difference in TLD-100 response between microcube and chip geometries. The intrinsic energy dependence and the absorbed-dose energy dependence deviated up to 10% between TLD-100 microcubes and chips.« less

Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for {sup 125}I and {sup 103}Pd brachytherapy sources relative to {sup 60}Co

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

Reed, J. L., E-mail: jlreed2@wisc.edu; Micka, J. A.; Culberson, W. S.

Purpose: To determine the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters (TLD-100) for {sup 125}I and {sup 103}Pd brachytherapy sources relative to {sup 60}Co. Methods: LiF:Mg,Ti TLDs were irradiated with low-energy brachytherapy sources and with a {sup 60}Co teletherapy source. The brachytherapy sources measured were the Best 2301 {sup 125}I seed, the OncoSeed 6711 {sup 125}I seed, and the Best 2335 {sup 103}Pd seed. The TLD light output per measured air-kerma strength was determined for the brachytherapy source irradiations, and the TLD light output per air kerma was determined for the {sup 60}Co irradiations. Monte Carlo (MC) simulations were usedmore » to calculate the dose-to-TLD rate per air-kerma strength for the brachytherapy source irradiations and the dose to TLD per air kerma for the {sup 60}Co irradiations. The measured and MC-calculated results for all irradiations were used to determine the TLD intrinsic energy dependence for {sup 125}I and {sup 103}Pd relative to {sup 60}Co. Results: The relative TLD intrinsic energy dependences (relative to {sup 60}Co) and associated uncertainties (k = 1) were determined to be 0.883 ± 1.3%, 0.870 ± 1.4%, and 0.871 ± 1.5% for the Best 2301 seed, OncoSeed 6711 seed, and Best 2335 seed, respectively. Conclusions: The intrinsic energy dependence of TLD-100 is dependent on photon energy, exhibiting changes of 13%–15% for {sup 125}I and {sup 103}Pd sources relative to {sup 60}Co. TLD measurements of absolute dose around {sup 125}I and {sup 103}Pd brachytherapy sources should explicitly account for the relative TLD intrinsic energy dependence in order to improve dosimetric accuracy.« less

Military personnel recognition system using texture, colour, and SURF features

NASA Astrophysics Data System (ADS)

Irhebhude, Martins E.; Edirisinghe, Eran A.

2014-06-01

This paper presents an automatic, machine vision based, military personnel identification and classification system. Classification is done using a Support Vector Machine (SVM) on sets of Army, Air Force and Navy camouflage uniform personnel datasets. In the proposed system, the arm of service of personnel is recognised by the camouflage of a persons uniform, type of cap and the type of badge/logo. The detailed analysis done include; camouflage cap and plain cap differentiation using gray level co-occurrence matrix (GLCM) texture feature; classification on Army, Air Force and Navy camouflaged uniforms using GLCM texture and colour histogram bin features; plain cap badge classification into Army, Air Force and Navy using Speed Up Robust Feature (SURF). The proposed method recognised camouflage personnel arm of service on sets of data retrieved from google images and selected military websites. Correlation-based Feature Selection (CFS) was used to improve recognition and reduce dimensionality, thereby speeding the classification process. With this method success rates recorded during the analysis include 93.8% for camouflage appearance category, 100%, 90% and 100% rates of plain cap and camouflage cap categories for Army, Air Force and Navy categories, respectively. Accurate recognition was recorded using SURF for the plain cap badge category. Substantial analysis has been carried out and results prove that the proposed method can correctly classify military personnel into various arms of service. We show that the proposed method can be integrated into a face recognition system, which will recognise personnel in addition to determining the arm of service which the personnel belong. Such a system can be used to enhance the security of a military base or facility.

Use of electron cyclotron resonance x-ray source for nondestructive testing application

NASA Astrophysics Data System (ADS)

Baskaran, R.; Selvakumaran, T. S.

2006-03-01

Electron cyclotron resonance (ECR) technique is being used for generating x rays in the low-energy region (<150keV). Recently, the source is used for the calibration of thermoluminescent dosimetry (TLD) badges. In order to qualify the ECR x-ray source for imaging application, the source should give uniform flux over the area under study. Lead collimation arrangement is made to get uniform flux. The flux profile is measured using a teletector at different distance from the port and uniform field region of 10×10cm2 has been marked at 20cm from the x-ray exit port. A digital-to-analog converter (DAC) circuit pack is used for examining the source performance. The required dose for nondestructive testing examination has been estimated using a hospital x-ray machine and it is found to be 0.05mSv. Our source experimental parameters are tuned and the DAC circuit pack was exposed for nearly 7min to get the required dose value. The ECR x-ray source operating parameters are argon pressure: 10-5Torr, microwave power: 350W, and coil current: 0A. The effective energy of the x-ray spectrum is nearly 40keV. The x-ray images obtained from ECR x-ray source and hospital medical radiography machine are compared. It is found that the image obtained from ECR x-ray source is suitable for NDT application.

Dose Analysis of the Model 112A Pulserad Pulsed X-Ray Generator by Its Cyltran

DTIC Science & Technology

1989-12-01

field was performed by R. B. Pietruszka [Ref. 1] using the dosimetry system which consists of Thermoluminescent Dosimeter ( TLD ) and associated TLD ...has the same pattern at a specific angle of the dominant electron flow. For a Marx charge of 75 kV, Figure 18 shows the absorbed dose in TLD normalized... Electron energy (1.66 MeV to 0.05 MeV) 3 materials 56 minutes 45 minutes (Ta, Al, TLD ) 68 APPENDIX F. MEASURED EXPOSURE VARIATION Marx Charge 75 kV

Localised and delocalised optically induced conversion of composite glow peak 5 in LiF:Mg,Ti (TLD-100) to glow peak 4 as a function of postirradiation annealing temperature.

PubMed

Horowitz, Y S; Einav, Y; Biderman, S; Oster, L

2002-01-01

The composite structure of glow peak 5 in LiF:Mg,Ti (TLD-100) has been investigated using optical bleaching by 310 nm (4 eV) light. The glow peak conversion efficiency of peak 5a (Tm = 187 degrees C) to peak 4 traps is very high at a value of 3+/-0.5 (1 SD) whereas the glow peak conversion efficiency of peak 5 (Tm = 205 degrees C) to peak 4 traps is 0.0026+/-0.0012 (1 SD). The high conversion efficiency of peak 5a to peak 4 arises from direct optical ionisation of the electron in the electron-hole pair. leaving behind a singly-trapped hole (peak 4), a direct mechanism, relatively free of competitive mechanisms. Optical ionisation of the 'singly-trapped' electron (peak 5), however, can lead to peak 4 only via multi-stage mechanisms involving charge carrier transport in the valence and conduction bands, a mechanism subject to competitive processes. The conduction/valence band competitive processes lead to the factor of one thousand decrease in the conversion efficiency of peak 5 compared to peak 5a.

Uncertainty analysis of absorbed dose calculations from thermoluminescence dosimeters.

PubMed

Kirby, T H; Hanson, W F; Johnston, D A

1992-01-01

Thermoluminescence dosimeters (TLD) are widely used to verify absorbed doses delivered from radiation therapy beams. Specifically, they are used by the Radiological Physics Center for mailed dosimetry for verification of therapy machine output. The effects of the random experimental uncertainties of various factors on dose calculations from TLD signals are examined, including: fading, dose response nonlinearity, and energy response corrections; reproducibility of TL signal measurements and TLD reader calibration. Individual uncertainties are combined to estimate the total uncertainty due to random fluctuations. The Radiological Physics Center's (RPC) mail out TLD system, utilizing throwaway LiF powder to monitor high-energy photon and electron beam outputs, is analyzed in detail. The technique may also be applicable to other TLD systems. It is shown that statements of +/- 2% dose uncertainty and +/- 5% action criterion for TLD dosimetry are reasonable when related to uncertainties in the dose calculations, provided the standard deviation (s.d.) of TL readings is 1.5% or better.

Effect of improved TLD dosimetry on the determination of dose rate constants for {sup 125}I and {sup 103}Pd brachytherapy seeds

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

Rodriguez, M., E-mail: manuel.rodriguez@rmp.uhn.ca; Rogers, D. W. O.

Purpose: To more accurately account for the relative intrinsic energy dependence and relative absorbed-dose energy dependence of TLDs when used to measure dose rate constants (DRCs) for {sup 125}I and {sup 103}Pd brachytherapy seeds, to thereby establish revised “measured values” for all seeds and compare the revised values with Monte Carlo and consensus values. Methods: The relative absorbed-dose energy dependence, f{sup rel}, for TLDs and the phantom correction, P{sub phant}, are calculated for {sup 125}I and {sup 103}Pd seeds using the EGSnrc BrachyDose and DOSXYZnrc codes. The original energy dependence and phantom corrections applied to DRC measurements are replaced bymore » calculated (f{sup rel}){sup −1} and P{sub phant} values for 24 different seed models. By comparing the modified measured DRCs to the MC values, an appropriate relative intrinsic energy dependence, k{sub bq}{sup rel}, is determined. The new P{sub phant} values and relative absorbed-dose sensitivities, S{sub AD}{sup rel}, calculated as the product of (f{sup rel}){sup −1} and (k{sub bq}{sup rel}){sup −1}, are used to individually revise the measured DRCs for comparison with Monte Carlo calculated values and TG-43U1 or TG-43U1S1 consensus values. Results: In general, f{sup rel} is sensitive to the energy spectra and models of the brachytherapy seeds. Values may vary up to 8.4% among {sup 125}I and {sup 103}Pd seed models and common TLD shapes. P{sub phant} values depend primarily on the isotope used. Deduced (k{sub bq}{sup rel}){sup −1} values are 1.074 ± 0.015 and 1.084 ± 0.026 for {sup 125}I and {sup 103}Pd seeds, respectively. For (1 mm){sup 3} chips, this implies an overall absorbed-dose sensitivity relative to {sup 60}Co or 6 MV calibrations of 1.51 ± 1% and 1.47 ± 2% for {sup 125}I and {sup 103}Pd seeds, respectively, as opposed to the widely used value of 1.41. Values of P{sub phant} calculated here have much lower statistical uncertainties than literature values, but

Grades out, Badges in

ERIC Educational Resources Information Center

Young, Jeffrey R.

2012-01-01

Grades are broken. Students grub for them, pick classes where good ones come easily, and otherwise hustle to win the highest scores for the least learning. As a result, college grades are inflated to the point of meaninglessness--especially to employers who want to know which diploma-holder is best qualified for their jobs. An alternative is to…

Communication strategies and timeliness of response to life critical telemetry alarms.

PubMed

Bonzheim, Kimberly A; Gebara, Rani I; O'Hare, Bridget M; Ellis, R Darin; Brand, Monique A; Balar, Salil D; Stockman, Rita; Sciberras, Annette M; Haines, David E

2011-05-01

A centralized electrocardiogram telemetry monitoring system (TMS) facilitates early identification of critical arrhythmias and acute medical decompensation. Timely intervention can only be performed if abnormalities are communicated rapidly to the direct caregiver. The study objectives were to measure effectiveness of bi-directional voice communication badges versus one-way alphanumeric pagers for telemetry alarm response and communication loop closure. A sequential observational pilot study of nursing response to TMS alarms compared communication technologies on four nursing units in a 1,061 bed tertiary care hospital with 264 TMS channels of telemetry over a 2-year period. Subsequently, the communication technologies were compared in a randomized fashion on a 68-bed progressive cardiac care unit. Caregivers were blinded to the protocol. All alarm responses were recorded during two periods using either pagers or voice communication devices. Alarm response time and closure of the communication loop were analyzed in a blinded fashion. The direct communication functionality of the badge significantly shortened the time to first contact, time to completion, and rate of closure of the communication loop in both the pilot and study phases. Median time to first contact with the communication badge was 0.5  min, compared to 1.6  min with pager communication (p < 0.0003). Communication loop closure was achieved in 100% of clinical alarms using the badge versus 19% with the pager (p < 0.0001). Communication badge technology reduced alarm time to first contact and completion as well as facilitated communication loop closures. Immediate two-way communication significantly impacted practice, alarm management, and resulted in faster bedside care.

Orange Is the New Who: Reflections on Teaching a College-Level Art Appreciation Course at Six New Jersey State Prisons

ERIC Educational Resources Information Center

McGuire, J. D.

2017-01-01

The process of entering prison as a civilian is such … sign in … send stuff through x-ray … walk through metal detector … get patted down by officer … show badge, get buzzed through steel door … get buzzed through another steel door … get buzzed through another steel door … show badge to officer, get buzzed through steel door. Enter the yard and…

Word Detection in Sung and Spoken Sentences in Children With Typical Language Development or With Specific Language Impairment

PubMed Central

Planchou, Clément; Clément, Sylvain; Béland, Renée; Cason, Nia; Motte, Jacques; Samson, Séverine

2015-01-01

Background: Previous studies have reported that children score better in language tasks using sung rather than spoken stimuli. We examined word detection ease in sung and spoken sentences that were equated for phoneme duration and pitch variations in children aged 7 to 12 years with typical language development (TLD) as well as in children with specific language impairment (SLI ), and hypothesized that the facilitation effect would vary with language abilities. Method: In Experiment 1, 69 children with TLD (7–10 years old) detected words in sentences that were spoken, sung on pitches extracted from speech, and sung on original scores. In Experiment 2, we added a natural speech rate condition and tested 68 children with TLD (7–12 years old). In Experiment 3, 16 children with SLI and 16 age-matched children with TLD were tested in all four conditions. Results: In both TLD groups, older children scored better than the younger ones. The matched TLD group scored higher than the SLI group who scored at the level of the younger children with TLD . None of the experiments showed a facilitation effect of sung over spoken stimuli. Conclusions: Word detection abilities improved with age in both TLD and SLI groups. Our findings are compatible with the hypothesis of delayed language abilities in children with SLI , and are discussed in light of the role of durational prosodic cues in words detection. PMID:26767070

Native Fluorescence Detection Methods and Detectors for Naphthalene and/or Other Volatile Organic Compound Vapors

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor)

2014-01-01

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds have been identified as serious health hazards. This is especially true for personnel working with JP8 jet fuel and other fuels containing naphthalene as well as other hazardous volatile organic compounds (VOCs). Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to naphthalene or other hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined. The badges employ a new native fluorescence based detection method to identify and differentiate VOCs. The particular focus of some embodiments are the detection and identification of naphthalene while other embodiments are directed to detection and identification of other VOCs like aromatic hydrocarbons such as benzene, toluene, and xylene.

Investigation of the Entrance Surface Dose and Dose to Different Organs in Lumbar Spine Imaging

PubMed Central

Sina, S; Zeinali, B; Karimipoorfard, M; Lotfalizadeh, F; Sadeghi, M; Zamani, E; Faghihi, R

2014-01-01

Background: Dose assessment using proper dosimeters is especially important in radiation protection optimization and imaging justification in diagnostic radiology. Objective: The aim of this study is to obtain the Entrance Skin Dose (ESD) of patients undergoing lumbar spine imaging using two thermoluminescence dosimeters TLD-100 (LiF: Mg, Ti) and GR-200 (LiF: Mg, Cu, P) and also to obtain the absorbed dose to different organs in lumbar spine imaging with several views. Methods: To measure the ESD values of the patients undergoing lumbar spine imaging, the two TLD types were put on their skin surface. The ESD values for different views of lumbar spine imaging were also measured by putting the TLDs at the surface of the Rando phantom. Several TLD chips were inserted inside different organs of Rando phantom to measure the absorbed dose to different organs in lumbar spine imaging. Results: The results indicate that there is a close agreement between the results of the two dosimeters. Based on the results of this experiment, the ESD dose of the 16 patients included in this study varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for GR-200 measurements. The ESDs obtained by putting the two types of TLDs at the surface of Rando phantom are in close agreement. Conclusion: According to the results, the GR200 has greater sensitivity than the TLD-100. PMID:25599058

WE-H-BRC-08: Examining Credentialing Criteria and Poor Performance Indicators for IROC Houston’s Anthropomorphic Head and Neck Phantom

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

Carson, M; Molineu, A; Taylor, P

Purpose: To analyze the most recent results of IROC Houston’s anthropomorphic H&N phantom to determine the nature of failing irradiations and the feasibility of altering pass/fail credentialing criteria. Methods: IROC Houston’s H&N phantom, used for IMRT credentialing for NCI-sponsored clinical trials, requires that an institution’s treatment plan must agree with measurement within 7% (TLD doses) and ≥85% pixels must pass 7%/4 mm gamma analysis. 156 phantom irradiations (November 2014 – October 2015) were re-evaluated using tighter criteria: 1) 5% TLD and 5%/4 mm, 2) 5% TLD and 5%/3 mm, 3) 4% TLD and 4%/4 mm, and 4) 3% TLD andmore » 3%/3 mm. Failure/poor performance rates were evaluated with respect to individual film and TLD performance by location in the phantom. Overall poor phantom results were characterized qualitatively as systematic (dosimetric) errors, setup errors/positional shifts, global but non-systematic errors, and errors affecting only a local region. Results: The pass rate for these phantoms using current criteria is 90%. Substituting criteria 1-4 reduces the overall pass rate to 77%, 70%, 63%, and 37%, respectively. Statistical analyses indicated the probability of noise-induced TLD failure at the 5% criterion was <0.5%. Using criteria 1, TLD results were most often the cause of failure (86% failed TLD while 61% failed film), with most failures identified in the primary PTV (77% cases). Other criteria posed similar results. Irradiations that failed from film only were overwhelmingly associated with phantom shifts/setup errors (≥80% cases). Results failing criteria 1 were primarily diagnosed as systematic: 58% of cases. 11% were setup/positioning errors, 8% were global non-systematic errors, and 22% were local errors. Conclusion: This study demonstrates that 5% TLD and 5%/4 mm gamma criteria may be both practically and theoretically achievable. Further work is necessary to diagnose and resolve dosimetric inaccuracy in these trials

Measurements of eye lens doses in interventional cardiology using OSL and electronic dosemeters†.

PubMed

Sanchez, R M; Vano, E; Fernandez, J M; Ginjaume, M; Duch, M A

2014-12-01

The purpose of this paper is to test the appropriateness of OSL and electronic dosemeters to estimate eye lens doses at interventional cardiology environment. Using TLD as reference detectors, personal dose equivalent was measured in phantoms and during clinical procedures. For phantom measurements, OSL dose values resulted in an average difference of -15 % vs. TLD. Tests carried out with other electronic dosemeters revealed differences up to ±20 % versus TLD. With dosemeters positioned outside the goggles and when TLD doses were >20 μSv, the average difference OSL vs. TLD was -9 %. Eye lens doses of almost 700 μSv per procedure were measured in two cases out of a sample of 33 measurements in individual clinical procedures, thus showing the risk of high exposure to the lenses of the eye when protection rules are not followed. The differences found between OSL and TLD are acceptable for the purpose and range of doses measured in the survey. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Toxicological Assessment of ISS Air Quality: September 2012 - October 2012 with Formaldehyde Supplement from May-October 2012

NASA Technical Reports Server (NTRS)

James, John T.

2013-01-01

A summary of the analytical results from 6 grab sample containers (GSCs) and 12 pairs of formaldehyde badges collected on ISS and returned aboard 29S or 31 S is shown in an accompanying table. The average recoveries of the 3 surrogate standards from the GSCs were as follows: C-l3-acetone, 128%; fluorobenzene, 114%; and chlorobenzene, 78%. Recoveries of two lab-control formaldehyde badges averaged 95%.

Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry.

PubMed

Bostani, Maryam; Mueller, Jonathon W; McMillan, Kyle; Cody, Dianna D; Cagnon, Chris H; DeMarco, John J; McNitt-Gray, Michael F

2015-02-01

The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for all exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. The calculated mean percent difference between TLD measurements and Monte Carlo simulations was -4.9% with standard deviation of 8.7% and a range of -22.7% to 5.7%. The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.

49 CFR 232.15 - Movement of defective equipment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the safe repair of the car. (d) Computation of percent operative power brakes. (1) The percentage of operative power brakes in a train shall be based on the number of control valves in the train. The... contained on the stencil, sticker, or badge plate required by § 232.103(g) for considering the power brakes...

Gamification: Questing to Integrate Content Knowledge, Literacy, and 21st-Century Learning

ERIC Educational Resources Information Center

Kingsley, Tara L.; Grabner-Hagen, Melissa M.

2015-01-01

This article showcases the use of gamification as a means to turn an existing curriculum into a game-based learning environment. The purpose of this article is to examine how gamification, coupled with effective pedagogy, can support the acquisition of 21st-century skills. Gamifying content allows students to earn experience points, badges, and…

The Impact of Expressiveness on the Effectiveness of Privacy Mechanisms for Location Sharing

DTIC Science & Technology

2008-12-01

of the ex- pected billions of dollars in marketing revenue from location - based services [13]. Despite the number of location-sharing applications that...privacy concerns [2, 25]. Many research groups have have developed location - based services : PARC’s Active Badges [37], ActiveCampus [3], MyCampus [29...location within social groups. In CHI ’08, pages 497–506, April 2008. [3] L. Barkhuus and A. Dey. Location - based services for mobile telephony: a study

Comparison of the calculated absorbed dose using the Cadplan™ treatment planning software and Tld-100 measurements in an Alderson-Rando phantom for a bronchogenic treatment

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

Gutiérrez Castillo, J. G., E-mail: jggc59@hotmail.com; Álvarez Romero, J. T., E-mail: trinidad.alvarez@inin.gob.mx, E-mail: fisarmandotorres@gmail.com, E-mail: victor.tovar@inin.gob.mx; Calderón, A. Torres, E-mail: trinidad.alvarez@inin.gob.mx, E-mail: fisarmandotorres@gmail.com, E-mail: victor.tovar@inin.gob.mx

2014-11-07

To verify the accuracy of the absorbed doses D calculated by a TPS Cadplan for a bronchogenic treatment (in an Alderson-Rando phantom) are chosen ten points with the following D's and localizations. Point 1, posterior position on the left edge with 136.4 Gy. Points: 2, 3 and 4 in the left lung with 104.9, 104.3 and 105.8 Gy, respectively; points 5 and 6 at the mediastinum with 192.4 and 173.5 Gy; points 7, 8 and 9 in the right lung with 105.8, 104.2 and 104.7 Gy, and 10 at posterior position on right edge with 143.7 Gy. IAEA type capsulesmore » with TLD 100 powder are placed, planned and irradiated. The evaluation of the absorbed dose is carried out a curve of calibration for the LiF response (nC) {sup vs} {sup DW}, to several cavity theories. The traceability for the DW is obtained with a secondary standard calibrated at the NRC (Canada). The dosimetric properties for the materials considered are determined from the Hounsfield numbers reported by the TPS. The stopping power ratios are calculated for nominal spectrum to 6 MV photons. The percent variations among the planned and determined D in all the cases they are < ± 3%.« less

Analysis of DNS Cache Effects on Query Distribution

PubMed Central

2013-01-01

This paper studies the DNS cache effects that occur on query distribution at the CN top-level domain (TLD) server. We first filter out the malformed DNS queries to purify the log data pollution according to six categories. A model for DNS resolution, more specifically DNS caching, is presented. We demonstrate the presence and magnitude of DNS cache effects and the cache sharing effects on the request distribution through analytic model and simulation. CN TLD log data results are provided and analyzed based on the cache model. The approximate TTL distribution for domain name is inferred quantificationally. PMID:24396313

Analysis of DNS cache effects on query distribution.

PubMed

Wang, Zheng

2013-01-01

This paper studies the DNS cache effects that occur on query distribution at the CN top-level domain (TLD) server. We first filter out the malformed DNS queries to purify the log data pollution according to six categories. A model for DNS resolution, more specifically DNS caching, is presented. We demonstrate the presence and magnitude of DNS cache effects and the cache sharing effects on the request distribution through analytic model and simulation. CN TLD log data results are provided and analyzed based on the cache model. The approximate TTL distribution for domain name is inferred quantificationally.

New design of textile light diffusers for photodynamic therapy.

PubMed

Cochrane, Cédric; Mordon, Serge R; Lesage, Jean Claude; Koncar, Vladan

2013-04-01

A homogeneous and reproducible fluence delivery rate during clinical photodynamic therapy (PDT) plays a determinant role in preventing under- or overtreatment. PDT applied in dermatology has been carried out with a wide variety of light sources delivering a broad range of more or less adapted light doses. Due to the complexities of the human anatomy, these light sources do not in fact deliver a uniform light distribution to the skin. Therefore, the development of flexible light sources would considerably improve the homogeneity of light delivery. The integration of plastic optical fiber (POF) into textile structures could offer an interesting alternative. In this article, a textile light diffuser (TLD) has been developed using POF and Polyester yarns. Predetermined POF macrobending leads to side emission of light when the critical angle is exceeded. Therefore, a specific pattern based on different satin weaves has been developed in order to improve light emission homogeneity and to correct the decrease of side emitted radiation intensity along POF. The prototyped fabrics (approximately 100 cm(2): 5×20 cm) were woven using a hand loom, then both ends of the POF were coupled to a laser diode (5 W, 635 nm). The fluence rate (mW/ cm(2)) and the homogeneity of light delivery by the TLD were evaluated. Temperature evolution, as a function of time, was controlled with an infrared thermographic camera. When using a power source of 5 W, the fluence rate of the TLD was 18±2.5 mw/cm(2). Due to the high efficiency of the TLD, the optical losses were very low. The TLD temperature elevation was 0.6 °C after 10 min of illumination. Our TLD meets the basic requirements for PDT: homogeneous light distribution and flexibility. It also proves that large (500 cm(2)) textile light diffusers adapted to skin, but also to peritoneal or pleural cavity, PDTs can be easily produced by textile manufacturing processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Surface dose measurements with commonly used detectors: a consistent thickness correction method

PubMed Central

Higgins, Patrick

2015-01-01

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30‐360) with other parallel plate chambers RMI‐449 (Attix), Capintec PS‐033, PTW 30‐329 (Markus) and Memorial. Measurements of surface dose for 6 MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (−0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid‐state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three‐detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth‐dose curves

Surface dose measurements with commonly used detectors: a consistent thickness correction method.

PubMed

Reynolds, Tatsiana A; Higgins, Patrick

2015-09-08

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30-360) with other parallel plate chambers RMI-449 (Attix), Capintec PS-033, PTW 30-329 (Markus) and Memorial. Measurements of surface dose for 6MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (-0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid-state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three-detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth-dose curves and is not

A Survey of Commercial Local Delivery Security Methods and Their Potential for Application at NSC (Naval Supply Center), San Diego, California.

DTIC Science & Technology

1986-12-01

Dry Provisions 35 ft. 4 40 ft. 3 --Trailer, 40 ft., flatbed 20 GSK --Trailer, 35 ft., lowboy 1 Bulk 55 ft., 1 Commercial Hire --Stake Truck, 2 / ton 2...wn r r r r------------ *0 warehouse area have plastic laminated badges. Visitors are also issued plastic identification badges after gate clearance...GSK material in warehouses is, therefore, considered very secure. In transit, GSK generally travels by flatbed trailer. Vans are not used because

War Literature. [Lesson Plan].

ERIC Educational Resources Information Center

Soderquist, Alisa

Based on Stephen Crane's poems about war and his novel "The Red Badge of Courage," this lesson plan presents activities designed to help students understand that Crane examined war-related themes in prose and poetry; that close study of a poem for oral presentation helps readers see meaning or techniques not noted earlier; and that not all readers…

The Thermoluminescent Response of Several Phosphors to Monoenergetic Photon Beams with Energies from 275 TO 2,550 EV.

NASA Astrophysics Data System (ADS)

Carrillo Beltran, Ricardo Enrique

The thermoluminescent (TL) response of LiF:Mg,Ti (TLD-100) and CaF_2:Dy (TLD-200) to monoenergetic photon beams was measured for photons with energies between 275 and 2,550 eV produced by the Aladdin synchrotron accelerator of the UW-Madison. The change of the TL response, as measured by the 130-215 ^circC integrated light output for TLD-100, the 170-250^circC TL interval for TLD-200 and the height of the main dosimetric peak at 200^circC for both phosphors as a function of total energy deposited up to saturation is described. Glow curves were determined for TLDs annealed in helium and irradiated at various photon energies. Glow curves showing the adverse effect of air annealing upon the TL sensitivity of these phosphors are presented as well. Supralinearity factors for each TLD type were calculated using the integrated TL and the main peak height and are listed for the photon energy beams employed. High surface doses were achieved with these irradiations because of the short mean free path of the photons and the even shorter range of the freed electrons, both plotted. Despite the shallower penetration of the photons in TLD-200 as compared to TLD-100, the former phosphor was found to be more suitable for routine use as a synchrotron radiation monitor because its TL properties change very little with photon energy as shown by its constant glow curve obtained. TLD-100 glow curve, either from a chip or a crystal, changed according to the photon energy employed; this adverse effect was more pronounced with the chips.

FADING EFFECT OF LiF:Mg,Ti AND LiF:Mg,Cu,P Ext-Rad AND WHOLE-BODY DETECTORS.

PubMed

Pereira, J; Pereira, M F; Rangel, S; Saraiva, M; Santos, L M; Cardoso, J V; Alves, J G

2016-09-01

Thermoluminescence dosemeters are widely used in individual and environmental monitoring. The aim of this work was to compare the thermal stability of dosemeters of the Ext-Rad and whole-body card types with LiF:Mg,Ti and LiF:Mg,Cu,P detectors stored at different temperatures and periods. The dosemeters were stored at 0°C, room temperature and 40°C for periods that lasted 8, 30, 45, 90 and 120 d. In general, TLD-100H detectors present higher TL signal stability than TLD-100 detectors. The intensity of the signal remained constant for both materials for storage periods at 0°C. At RT the same results was observed for TLD-100H. For TLD-100 detectors, a maximum variation of 22 % was registered for the longest period. At 40°C the TL signal decreased with storage time for both detectors. The TL signal of TLD-100H detectors presented maximum variations of 12 % whereas for TLD-100 detectors, larger variations of 25 % were observed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The response of a thermoluminescent dosimeter to low energy protons in the range 30-100 keV.

PubMed

Chu, T C; Lin, S Y; Hsu, C C; Li, J P

2001-11-01

This study demonstrates the thermoluminescence (TL) response of CaF2:Tm (commercial name TLD-300) to 30-100 keV protons which were generated by means of a Cockcroft-Walton accelerator. The phenomenon in which the total thermoluminescent output from CaF2:Tm (TLD-300) decreases with proton energy from 30 to 100 keV (with increase of LET) can be interpreted by the track structure theory (TST). The analysis of the glow peaks: P2 (131 degrees C), P3 (153.5 degrees C) and P6 (259 degrees C), of TLD-300 show the oscillatory decreasing phenomenon as a function of incident proton energy, which can be interpreted with the TST and the oscillatory emission of electrons in a thermoluminescent dosimeter (TLD) that is caused by resonant or quasi-resonant charge transfer in ion-atom interactions in this TLD-300.

Space Science Investigation: NASA ISS Stowage Simulator

NASA Technical Reports Server (NTRS)

Crawford, Gary

2017-01-01

During this internship the opportunity was granted to work with the Integrated, Graphics, Operations and Analysis Laboratory (IGOAL) team. The main assignment was to create 12 achievement patches for the Space Station training simulator called the "NASA ISS Stowage Training Game." This project was built using previous IGOAL developed software. To accomplish this task, Adobe Photoshop and Adobe Illustrator were used to craft the badges and other elements required. Blender, a 3D modeling software, was used to make the required 3D elements. Blender was a useful tool to make things such as a CTB bag for the "No More Bob" patch which shows a gentleman kicking a CTB bag into the distance. It was also used to pose characters to the positions that was optimal for their patches as in the "Station Sanitation" patch which portrays and astronaut waving on a U.S module on a truck. Adobe Illustrator was the main piece of software for this task. It was used to craft the badges and upload them when they were completed. The style of the badges were flat, meaning that they shouldn't look three dimensional in any way, shape or form. Adobe Photoshop was used when any pictures need brightening and was where the texture for the CTB bag was made. In order for the patches to be ready for the game's next major release, they have to go under some critical reviewing, revising and re-editing to make sure the other artists and the rest of the staff are satisfied with the final products. Many patches were created and revamped to meet the flat setting and incorporate suggestions from the IGOAL team. After the three processes were completed, the badges were implemented into the game (reference fig1 for badges). After a month of designing badges, the finished products were placed into the final game build via the programmers. The art was the final piece in showcasing the latest build to the public for testing. Comments from the testers were often exceptional and the feedback on the badges were

Capturing Location-Privacy Preferences: Quantifying Accuracy and User-Burden Tradeoffs

DTIC Science & Technology

2010-03-01

research groups have developed location - based services , including PARC’s Active Badges [24], Active- Campus [2], MyCampus [17], Intel’s PlaceLab [11], and...groups. In Conference on Human Factors in Computing Systems (CHI), 2008. [2] L. Barkhuus and A. Dey. Location - based services for mobile telephony: A... location - based services . In OnTheMove Conferences (OTM), 2009. [6] K. Connelly, A. Khalil, and Y. Liu. Do I do what I say?: Observed versus stated privacy

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

Radiation Surveys of the Naval Postgraduate School LINAC.

DTIC Science & Technology

1992-06-01

personnel dosimetry at the NPS LINAC. This will result in the reduction of the TLD measured neutron dose evaluation for personnel. Accession For NTIS F. A...29 ix Figure 16: Average TLD NECF for electron energy and slit width co m b inatio ns...values obtained at 90 MeV electron energy, or NECFfmal = 0.341 ± 0.015 TABLE 5: AVERAGE TLD NEUTRON ENERGY CORRECTION FACTORS Electron Energy S lit

Recalibration of indium foil for personnel screening in criticality accidents.

PubMed

Takada, C; Tsujimura, N; Mikami, S

2011-03-01

At the Nuclear Fuel Cycle Engineering Laboratories of the Japan Atomic Energy Agency (JAEA), small pieces of indium foil incorporated into personal dosemeters have been used for personnel screening in criticality accidents. Irradiation tests of the badges were performed using the SILENE reactor to verify the calibration of the indium activation that had been made in the 1980s and to recalibrate them for simulated criticalities that would be the most likely to occur in the solution process line. In addition, Monte Carlo calculations of the indium activation using the badge model were also made to complement the spectral dependence. The results lead to a screening level of 15 kcpm being determined that corresponds to a total dose of 0.25 Gy, which is also applicable in posterior-anterior exposure. The recalibration based on the latest study will provide a sounder basis for the screening procedure in the event of a criticality accident.

Ambient Dose Equivalent in S. Paulo and Bauru cities

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

Umisedo, Nancy K.; Okuno, Emico; Cancio, Francisco S.

2008-08-07

The Laboratory of Dosimetry (Institute of Physics, University of S. Paulo) performs since 1981 the external individual monitoring of workers exposed to X and gamma rays based on thermoluminescent dosimetry (TLD). Personal dose equivalent refers only to the exposure of workers due to the working activities, and the dose due to background radiation, also measured with TLD, must be subtracted to evaluate it. A compilation of ambient dose equivalent was done to evaluate the dose due to the background radiation in the work places, and also to contribute to the knowledge of the level of indoor radiation to which themore » public is exposed.« less

Sociometric Indicators of Leadership: An Exploratory Analysis

DTIC Science & Technology

2018-01-01

streamline existing observational protocols and assessment methods . This research provides an initial test of sociometric badges in the context of the U.S...understand, the requirements of the mission. Traditional research and assessment methods focusing on leader and follower interactions require direct...based methods of social network analysis. Novel Measures of Leadership Building on these findings and earlier research , it is apparent that

Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry

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

Bostani, Maryam, E-mail: mbostani@mednet.ucla.edu; McMillan, Kyle; Cagnon, Chris H.

Purpose: The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. Methods: MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for allmore » exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. Results: The calculated mean percent difference between TLD measurements and Monte Carlo simulations was −4.9% with standard deviation of 8.7% and a range of −22.7% to 5.7%. Conclusions: The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.« less

Can mental health and readjustment be improved in UK military personnel by a brief period of structured postdeployment rest (third location decompression)?

PubMed

Jones, Norman; Jones, Margaret; Fear, Nicola T; Fertout, Mohammed; Wessely, Simon; Greenberg, Neil

2013-07-01

Third Location Decompression (TLD) is an activity undertaken by UK Armed Forces (UK AF) personnel at the end of an operational deployment which aims to smooth the transition between operations and returning home. We assessed whether TLD impacted upon both mental health and postdeployment readjustment. Data collected during a large cohort study was examined to identify personnel who either engaged in TLD or returned home directly following deployment. Propensity scores were generated and used to calculate inverse probability of treatment weights in adjusted regression analyses to compare mental health outcomes and postdeployment readjustment problems. TLD had a positive impact upon mental health outcomes (post-traumatic stress disorder (PTSD) and multiple physical symptoms) and levels of harmful alcohol use. However, when the samples were stratified by combat exposure, although postdeployment readjustment was similar for all exposure levels, personnel experiencing low and moderate levels of combat exposure experienced the greatest positive mental health effects. We found no evidence to suggest that TLD promotes better postdeployment readjustment; however, we found a positive impact upon alcohol use and mental health with an interaction with degree of combat exposure. This study suggests that TLD is a useful postdeployment transitional activity that may help to improve PTSD symptoms and alcohol use in UK AF personnel.

[Roentgenomorphological substantiation of drainage of the thoracic duct in patients with liver cirrhosis].

PubMed

Riabukhin, I A; Nazyrov, F G; Vorozheĭkin, V M; Khamidov, P M; Kirichenko, I P

1983-04-01

On the basis of an analysis of rentgeno-morphological investigations of the thoracic lymphatic duct (TLD) in 115 patients with complications of hepatocirrhosis and 50 postmortem observations the authors make a conclusion that one of the main factors of the development of insufficiency of TLD in hepatocirrhosis is an excess of lymph resulting in congestion in the duct. It may be considered as a cause for drainage of the TLD in patients with hepatocirrhosis.

Utilization of thermoluminescent dosimetry in total skin electron beam radiotherapy of mycosis fungoides.

PubMed

Antolak, J A; Cundiff, J H; Ha, C S

1998-01-01

The purpose of this report is to discuss the utilization of thermoluminescent dosimetry (TLD) in total skin electron beam (TSEB) radiotherapy to: (a) compare patient dose distributions for similar techniques on different machines, (b) confirm beam calibration and monitor unit calculations, (c) provide data for making clinical decisions, and (d) study reasons for variations in individual dose readings. We report dosimetric results for 72 cases of mycosis fungoides, using similar irradiation techniques on two different linear accelerators. All patients were treated using a modified Stanford 6-field technique. In vivo TLD was done on all patients, and the data for all patients treated on both machines was collected into a database for analysis. Means and standard deviations (SDs) were computed for all locations. Scatter plots of doses vs. height, weight, and obesity index were generated, and correlation coefficients with these variables were computed. The TLD results show that our current TSEB implementation is dosimetrically equivalent to the previous implementation, and that our beam calibration technique and monitor unit calculation is accurate. Correlations with obesity index were significant at several sites. Individual TLD results allow us to customize the boost treatment for each patient, in addition to revealing patient positioning problems and/or systematic variations in dose caused by patient variability. The data agree well with previously published TLD results for similar TSEB techniques. TLD is an important part of the treatment planning and quality assurance programs for TSEB, and routine use of TLD measurements for TSEB is recommended.

Long-term outcome of surgical disconnection of the epileptic zone as an alternative to resection for nonlesional mesial temporal epilepsy.

PubMed

Massager, Nicolas; Tugendhaft, Patrick; Depondt, Chantal; Coppens, Thomas; Drogba, Landry; Benmebarek, Nadir; De Witte, Olivier; Van Bogaert, Patrick; Legros, Benjamin

2013-12-01

Pharmacoresistant epilepsy can be treated by either resection of the epileptic focus or functional isolation of the epileptic focus through complete disconnection of the pathways of propagation of the epileptic activity. To evaluate long-term seizure outcome and complications of temporal lobe disconnection (TLD) without resection for mesial temporal lobe epilepsy (MTLE). Data of 45 patients operated on for intractable MTLE using a functional disconnection procedure have been studied. Indication of TLD surgery was retained after a standard preoperative evaluation of refractory epilepsy and using the same criteria as for standard temporal resection. Mean follow-up duration was 3.7 years. At the last follow-up, 30 patients (67%) were completely seizure-free (Engel-Ia/International League Against Epilepsy class 1) and 39 patients (87%) remained significantly improved (Engel-I or -II) by surgery. Actuarial outcome displays a 77.7% probability of being seizure-free and an 85.4% probability of being significantly improved at 5 years. No patient died after surgery and no subdural haematoma or hygroma occurred. Permanent morbidity included hemiparesis, hemianopia and oculomotor paresis found in three, five and one patient, respectively, after TLD. TLD is acceptable alternative surgical technique for patients with intractable MTLE. The results of TLD are in the range of morbidity and long-term seizure outcome rates after standard surgical resection. We observed a slightly higher rate of complications after TLD in comparison with usual rates of morbidity of resection procedures. TLD may be used as an alternative to resection and could reduce operating time and the risks of subdural collections.

LABRADOR: a learning autonomous behavior-based robot for adaptive detection and object retrieval

NASA Astrophysics Data System (ADS)

Yamauchi, Brian; Moseley, Mark; Brookshire, Jonathan

2013-01-01

As part of the TARDEC-funded CANINE (Cooperative Autonomous Navigation in a Networked Environment) Program, iRobot developed LABRADOR (Learning Autonomous Behavior-based Robot for Adaptive Detection and Object Retrieval). LABRADOR was based on the rugged, man-portable, iRobot PackBot unmanned ground vehicle (UGV) equipped with an explosives ordnance disposal (EOD) manipulator arm and a custom gripper. For LABRADOR, we developed a vision-based object learning and recognition system that combined a TLD (track-learn-detect) filter based on object shape features with a color-histogram-based object detector. Our vision system was able to learn in real-time to recognize objects presented to the robot. We also implemented a waypoint navigation system based on fused GPS, IMU (inertial measurement unit), and odometry data. We used this navigation capability to implement autonomous behaviors capable of searching a specified area using a variety of robust coverage strategies - including outward spiral, random bounce, random waypoint, and perimeter following behaviors. While the full system was not integrated in time to compete in the CANINE competition event, we developed useful perception, navigation, and behavior capabilities that may be applied to future autonomous robot systems.

Remote auditing of radiotherapy facilities using optically stimulated luminescence dosimeters

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

Lye, Jessica, E-mail: jessica.lye@arpansa.gov.au; Dunn, Leon; Kenny, John

Purpose: On 1 July 2012, the Australian Clinical Dosimetry Service (ACDS) released its Optically Stimulated Luminescent Dosimeter (OSLD) Level I audit, replacing the previous TLD based audit. The aim of this work is to present the results from this new service and the complete uncertainty analysis on which the audit tolerances are based. Methods: The audit release was preceded by a rigorous evaluation of the InLight® nanoDot OSLD system from Landauer (Landauer, Inc., Glenwood, IL). Energy dependence, signal fading from multiple irradiations, batch variation, reader variation, and dose response factors were identified and quantified for each individual OSLD. The detectorsmore » are mailed to the facility in small PMMA blocks, based on the design of the existing Radiological Physics Centre audit. Modeling and measurement were used to determine a factor that could convert the dose measured in the PMMA block, to dose in water for the facility's reference conditions. This factor is dependent on the beam spectrum. The TPR{sub 20,10} was used as the beam quality index to determine the specific block factor for a beam being audited. The audit tolerance was defined using a rigorous uncertainty calculation. The audit outcome is then determined using a scientifically based two tiered action level approach. Audit outcomes within two standard deviations were defined as Pass (Optimal Level), within three standard deviations as Pass (Action Level), and outside of three standard deviations the outcome is Fail (Out of Tolerance). Results: To-date the ACDS has audited 108 photon beams with TLD and 162 photon beams with OSLD. The TLD audit results had an average deviation from ACDS of 0.0% and a standard deviation of 1.8%. The OSLD audit results had an average deviation of −0.2% and a standard deviation of 1.4%. The relative combined standard uncertainty was calculated to be 1.3% (1σ). Pass (Optimal Level) was reduced to ≤2.6% (2σ), and Fail (Out of Tolerance) was reduced to

Gray-white matter and cerebrospinal fluid volume differences in children with Specific Language Impairment and/or Reading Disability.

PubMed

Girbau-Massana, Dolors; Garcia-Marti, Gracian; Marti-Bonmati, Luis; Schwartz, Richard G

2014-04-01

We studied gray-white matter and cerebrospinal fluid (CSF) alterations that may be critical for language, through an optimized voxel-based morphometry evaluation in children with Specific Language Impairment (SLI), compared to Typical Language Development (TLD). Ten children with SLI (8;5-10;9) and 14 children with TLD (8;2-11;8) participated. They received a comprehensive language and reading test battery. We also analyzed a subgroup of six children with SLI+RD (Reading Disability). Brain images from 3-Tesla MRIs were analyzed with intelligence, age, gender, and total intracranial volume as covariates. Children with SLI or SLI+RD exhibited a significant lower overall gray matter volume than children with TLD. Particularly, children with SLI showed a significantly lower volume of gray matter compared to children with TLD in the right postcentral parietal gyrus (BA4), and left and right medial occipital gyri (BA19). The group with SLI also exhibited a significantly greater volume of gray matter in the right superior occipital gyrus (BA19), which may reflect a brain reorganization to compensate for their lower volumes at medial occipital gyri. Children with SLI+RD, compared to children with TLD, showed a significantly lower volume of: (a) gray matter in the right postcentral parietal gyrus; and (b) white matter in the right inferior longitudinal fasciculus (RILF), which interconnects the temporal and occipital lobes. Children with TLD exhibited a significantly lower CSF volume than children with SLI and children with SLI+RD respectively, who had somewhat smaller volumes of gray matter allowing for more CSF volume. The significant lower gray matter volume at the right postcentral parietal gyrus and greater cerebrospinal fluid volume may prove to be unique markers for SLI. We discuss the association of poor knowledge/visual representations and language input to brain development. Our comorbid study showed that a significant lower volume of white matter in the right

Basic Characteristics of Laser Heating in Thermoluminescence and of Laser-Stimulated Luminescence

DTIC Science & Technology

1990-07-15

as examples. These include LiF:Mg,Ti ( TLD -100, Harshaw Chemical Corporation) in form of chips, which are widely used in the dosimetry of ionizing...take dosimetry ( TLD ) of ionizing radiation because it holds pro- the form of discrete circular spots whose diameter is smaller mise as a solution to...function of typical phosphor, we choose the most widely used dosimetry time after onset of the laser exposure, the time-dependent material LiF:Mg,Ti ( TLD

Active and passive ozone samplers based on a reaction with a binary reagent.

PubMed

Hackney, J D; Avol, E L; Linn, W S; Anderson, K R

1994-02-01

Ozone is one of the most toxic common air pollutants (judging from short-term animal and human exposure studies at realistic concentrations) and one of the most difficult and expensive pollutants to control. Because of ozone's high chemical reactivity, its concentrations may vary greatly over short distances, and fixed-site air quality monitors may not accurately estimate exposures of human populations. Epidemiologic research on ozone's long-term health effects has been inconclusive, partly because of the lack of reliable personal exposure information. The objective of this project was to develop a practical personal ozone exposure monitoring technique, and to document its precision and accuracy in actual use by representatives of freely ranging, ozone-exposed populations. The project site, Los Angeles, is the nation's metropolitan area with the highest level of ozone pollution and, thus, probably the most important locale for personal exposure assessment. Our overall strategy was (1) to select the most promising laboratory technique for ozone detection from published literature and private communications; (2) to design and test personal monitors using this technique; and (3) when feasible, to evaluate concurrently alternative methodologies developed by others. As indicated below, parts 1 and 2 of our strategy yielded a limited success with respect to short-term active sampling, i.e., measuring personal ozone exposure levels during one to two hours with a monitor incorporating a battery-powered air pump of the type used in industrial hygiene investigations. The same approach was not successful in passive sampling, i.e., measuring exposure levels during multihour or multiday periods with a light-weight, diffusion-controlled "badge" sampler having no moving parts. Passive badge samplers could be calibrated reasonably well in laboratory exposures to ozone in otherwise pure air, but they greatly overestimated ozone levels in outdoor ambient air. Part 3 of our strategy

The quality of mental health information commonly searched for on the Internet.

PubMed

Grohol, John M; Slimowicz, Joseph; Granda, Rebecca

2014-04-01

Previous research has reviewed the quality of online information related to specific mental disorders. Yet, no comprehensive study has been conducted on the overall quality of mental health information searched for online. This study examined the first 20 search results of two popular search engines-Google and Bing-for 11 common mental health terms. They were analyzed using the DISCERN instrument, an adaptation of the Depression Website Content Checklist (ADWCC), Flesch Reading Ease and Flesch-Kincaid Grade Level readability measures, HONCode badge display, and commercial status, resulting in an analysis of 440 web pages. Quality of Web site results varied based on type of disorder examined, with higher quality Web sites found for schizophrenia, bipolar disorder, and dysthymia, and lower quality ratings for phobia, anxiety, and panic disorder Web sites. Of the total Web sites analyzed, 67.5% had good or better quality content. Nearly one-third of the search results produced Web sites from three entities: WebMD, Wikipedia, and the Mayo Clinic. The mean Flesch Reading Ease score was 41.21, and the mean Flesch-Kincaid Grade Level score was 11.68. The presence of the HONCode badge and noncommercial status was found to have a small correlation with Web site quality, and Web sites displaying the HONCode badge and commercial sites had lower readability scores. Popular search engines appear to offer generally reliable results pointing to mostly good or better quality mental health Web sites. However, additional work is needed to make these sites more readable.

Social knowledge and signals in primates.

PubMed

Bergman, Thore J; Sheehan, Michael J

2013-07-01

Primates are notable for having a rich and detailed understanding of their social environment and there has been great interest in the evolution and function of social knowledge in primates. Indeed, primates have been shown to have impressive understandings of not only other group members but also the complex relationships among them. To be useful, however, social knowledge requires memories from previous encounters and observations about individual traits that are stable. Here, we argue that social systems or traits that make social knowledge more costly or less accurate will favor signals that either supplement or replace social knowledge. Thus, the relationship between signals and social knowledge can be complementary or antagonistic depending on the type of signal. Our goal in this review is to elucidate the relationships between signals and social knowledge in primates. We categorize signals into three types, each with different relationships to social knowledge. (1) Identity signals directly facilitate social knowledge, (2) current-state signals supplement information gained through social knowledge, and (3) badges of status replace social knowledge. Primates rely extensively on identity information, but it remains to be determined to what extent this is based on receiver perception of individual variation or senders using identity signals. Primates frequently utilize current-state signals including signals of intent to augment their interactions with familiar individuals. Badges of status are rare in primates, and the cases where they are used point to a functional and evolutionary trade-off between badges of status and social knowledge. However, the nature of this relationship needs further exploration. © 2012 Wiley Periodicals, Inc.

SRAG Measurements Performed During the Orion EFT-1 Mission

NASA Technical Reports Server (NTRS)

Gaza, Ramona

2015-01-01

The Exploration Flight Test 1 (EFT-1) was the first flight of the Orion Multi-Purpose Crew Vehicle (MPCV). The flight was launched on December 5, 2014, by a Delta IV Heavy rocket and lasted 4.5 hours. The EFT-1 trajectory involved one low altitude orbit and one high altitude orbit with an apogee of almost 6000 km. As a result of this particular flight profile, the Orion MPCV passed through intense regions of trapped protons and electron belts. In support of the radiation measurements aboard the EFT-1, the Space Radiation Analysis Group (SRAG) provided a Battery-operated Independent Radiation Detector (BIRD) based on Timepix radiation monitoring technology similar to that employed by the ISS Radiation Environmental Monitors (REM). In addition, SRAG provided a suite of optically and thermally stimulated luminescence detectors, with 2 Radiation Area Monitor (RAM) units collocated with the BIRD instrument for comparison purposes, and 6 RAM units distributed at different shielding configurations within the Orion MPCV. A summary of the EFT-1 Radiation Area Monitors (RAM) mission dose results obtained from measurements performed in the Space Radiation Dosimetry Laboratory at the NASA Johnson Space Center will be presented. Each RAM included LiF:Mg,Ti (TLD-100), (6)LiF:Mg,Ti (TLD-600), (7)LiF:Mg,Ti (TLD-700), Al2O3:C (Luxel trademark), and CaF2:Tm (TLD-300). The RAM mission dose values will be compared with the BIRD instrument total mission dose. In addition, a similar comparison will be shown for the ISS environment by comparing the ISS RAM data with data from the six Timepix-based REM units deployed on ISS as part of the NASA REM Technology Demonstration.

Evaluating the consistency of location of the most severe acute skin reaction and highest skin dose measured by thermoluminescent dosimeter during radiotherapy for breast cancer.

PubMed

Sun, Li-Min; Huang, Chih-Jen; Chen, Hsiao-Yun; Chang, Gia-Hsin; Tsao, Min-Jen

2016-01-01

We conducted this prospective study to evaluate whether the location of the most severe acute skin reaction matches the highest skin dose measured by thermoluminescent dosimeter (TLD) during adjuvant radiotherapy (RT) for patients with breast cancer after breast conservative surgery. To determine whether TLD measurement can reflect the location of the most severe acute skin reaction, 80 consecutive patients were enrolled in this prospective study. We divided the irradiated field into breast, axillary, inframammary fold, and areola/nipple areas. In 1 treatment session when obvious skin reaction occurred, we placed the TLD chips onto the 4 areas and measured the skin dose. We determined whether the highest measured skin dose area is consistent with the location of the most severe skin reaction. The McNemar test revealed that the clinical skin reaction and TLD measurement are more consistent when the most severe skin reaction occurred at the axillary area, and the p = 0.0108. On the contrary, TLD measurement of skin dose is less likely consistent with clinical observation when the most severe skin reaction occurred at the inframammary fold, breast, and areola/nipple areas (all the p > 0.05). Considering the common site of severe skin reaction over the axillary area, TLD measurement may be an appropriate way to predict skin reaction during RT. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Evaluating the consistency of location of the most severe acute skin reaction and highest skin dose measured by thermoluminescent dosimeter during radiotherapy for breast cancer

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

Sun, Li-Min, E-mail: limin.sun@yahoo.com; Huang, Chih-Jen; Department of Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan

We conducted this prospective study to evaluate whether the location of the most severe acute skin reaction matches the highest skin dose measured by thermoluminescent dosimeter (TLD) during adjuvant radiotherapy (RT) for patients with breast cancer after breast conservative surgery. To determine whether TLD measurement can reflect the location of the most severe acute skin reaction, 80 consecutive patients were enrolled in this prospective study. We divided the irradiated field into breast, axillary, inframammary fold, and areola/nipple areas. In 1 treatment session when obvious skin reaction occurred, we placed the TLD chips onto the 4 areas and measured the skinmore » dose. We determined whether the highest measured skin dose area is consistent with the location of the most severe skin reaction. The McNemar test revealed that the clinical skin reaction and TLD measurement are more consistent when the most severe skin reaction occurred at the axillary area, and the p = 0.0108. On the contrary, TLD measurement of skin dose is less likely consistent with clinical observation when the most severe skin reaction occurred at the inframammary fold, breast, and areola/nipple areas (all the p > 0.05). Considering the common site of severe skin reaction over the axillary area, TLD measurement may be an appropriate way to predict skin reaction during RT.« less

The use of in vivo thermoluminescent dosimeters in the quality assurance programme for the START breast fractionation trial.

PubMed

Venables, Karen; Miles, Elizabeth A; Aird, Edwin G A; Hoskin, Peter J

2004-06-01

The use of in vivo dosimetry for patient measurement is recommended in many publications. It provides an additional check to verify that the dose delivered to the patient corresponds to the prescribed dose. In the context of a clinical trial investigating the effects of different fractionation regimens, it is imperative that the dose given is that prescribed to ensure that noise in the data between centres does not mask the results of the trial. The methodology for in vivo measurement in a clinical trial of breast radiotherapy was developed and verified. A cohort of patients in the STAndardisation of breast RadioTherapy (START) trial was monitored using postal thermoluminescent dosimeters chips (TLD). All TLD were processed and analysed at Mount Vernon Hospital. Patients for in vivo measurements were identified at randomisation as a random 1 in 9 samples for the first 2500 patients randomised (282 TLD) increasing to 1 in 3 thereafter. The TLD were left in place for the duration of the tangential field treatment and thus a composite entrance and exit dose was recorded. TLD measurements were performed on 429 patients from 33 hospitals. The average ratio of dose measured using TLD to that prescribed was 0.99+/-0.04. Eight patients had initial measurements more than 10% different to the prescribed dose. The mean TLD results for a given centre correlated well with dose measurements performed using an ionisation chamber in a breast shaped phantom at that centre as part of the START trial audit. Thermoluminescence dosimetry has provided useful quality assurance information on the doses received by patients in centres participating in the START trial.

Detection of leachables and cytotoxicity after exposure to methacrylate- and epoxy-based root canal sealers in vitro.

PubMed

Lodienė, Greta; Kopperud, Hilde M; Ørstavik, Dag; Bruzell, Ellen M

2013-10-01

Root canal sealing materials may have toxic potential in vitro depending on the cell line, cytotoxicity assay, material chemistry, and degree of polymer curing. The aims of the present study were to detect leaching components from epoxy- or methacrylate-based root canal sealers and to investigate the degree of cytotoxicity after exposure to extracts from these materials. Qualitative determination of substances released from the materials was performed by gas- and liquid chromatography/mass spectrometry. Submandibular salivary gland acinar cell death (apoptosis/necrosis) was determined using a fluorescence staining/microscopy technique. The major leachable monomer from the epoxy-based material was bisphenol-A diglycidyl ether (BADGE), whereas leachables from the methacrylate-based materials were mainly triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), hydroxyethyl methacrylate (HEMA), and polyethyleneglycol dimethacrylate (PEGDMA). Exposure to diluted extracts of cured methacrylate-based materials caused a postexposure time-dependent increase in cell death. This effect was not demonstrated as a result of exposure to undiluted extract of cured epoxy-based material. Extracts of all fresh materials induced apoptosis significantly, but at lower dilutions of the epoxy- than the methacrylate-based materials. The degree of leaching, determined from the relative chromatogram peak heights of eluates from the methacrylate-based sealer materials, corresponded with the degree of cell death induced by extracts of these materials. © 2013 Eur J Oral Sci.

The Identification of Novel Diagnostic Marker Genes for the Detection of Beer Spoiling Pediococcus damnosus Strains Using the BlAst Diagnostic Gene findEr

PubMed Central

Schmid, Jonas; Zehe, Anja; Vogel, Rudi F.

2016-01-01

As the number of bacterial genomes increases dramatically, the demand for easy to use tools with transparent functionality and comprehensible output for applied comparative genomics grows as well. We present BlAst Diagnostic Gene findEr (BADGE), a tool for the rapid prediction of diagnostic marker genes (DMGs) for the differentiation of bacterial groups (e.g. pathogenic / nonpathogenic). DMG identification settings can be modified easily and installing and running BADGE does not require specific bioinformatics skills. During the BADGE run the user is informed step by step about the DMG finding process, thus making it easy to evaluate the impact of chosen settings and options. On the basis of an example with relevance for beer brewing, being one of the oldest biotechnological processes known, we show a straightforward procedure, from phenotyping, genome sequencing, assembly and annotation, up to a discriminant marker gene PCR assay, making comparative genomics a means to an end. The value and the functionality of BADGE were thoroughly examined, resulting in the successful identification and validation of an outstanding novel DMG (fabZ) for the discrimination of harmless and harmful contaminations of Pediococcus damnosus, which can be applied for spoilage risk determination in breweries. Concomitantly, we present and compare five complete P. damnosus genomes sequenced in this study, finding that the ability to produce the unwanted, spoilage associated off-flavor diacetyl is a plasmid encoded trait in this important beer spoiling species. PMID:27028007

Investigating Time and Spectral Dependence in Neutron Radiation Environments for Semiconductor Damage Studies

DTIC Science & Technology

2014-09-18

each of the four 20-min dosimetry -focused irradiations, a TLD crystal was included in the dosimetry package placed next to the BJTs. This TLD was then...4.75× 103 rad(Si). One reason the measured TLD response would be higher than the calculated value may be due to neutron-induced electron excitation that...there were also 14 TLDs . The dosimetry packet 122 for the 23.4% irradiation did not contain TLDs because they would have become too radioactive and would

Thermoluminescence Response of CaF2:Mn, CaFz:Dy and CaSO4:Tm to Protons and Alpha-Particles,

DTIC Science & Technology

1987-06-01

TLD ) in diverse radiation fields, such as mixed neutron-gamma fields. TL responses of the detector may depend not only on the photon and neutron energy...response of three TLD materials: CaF 2 :Mn, CaF?:Dy and CaSO 4 :Tm. These three materials are commonly used in TLDs , because of their high sensitivities...and suitable readout temperatures. CaS04:Tm powder embedded in polyethylene was investiaged at DREO (Ref. (4)) as a combined neutron/gamma TLD , but

Age-Based Methods to Explore Time-Related Variables in Occupational Epidemiology Studies

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

Janice P. Watkins, Edward L. Frome, Donna L. Cragle

2005-08-31

Although age is recognized as the strongest predictor of mortality in chronic disease epidemiology, a calendar-based approach is often employed when evaluating time-related variables. An age-based analysis file, created by determining the value of each time-dependent variable for each age that a cohort member is followed, provides a clear definition of age at exposure and allows development of diverse analytic models. To demonstrate methods, the relationship between cancer mortality and external radiation was analyzed with Poisson regression for 14,095 Oak Ridge National Laboratory workers. Based on previous analysis of this cohort, a model with ten-year lagged cumulative radiation doses partitionedmore » by receipt before (dose-young) or after (dose-old) age 45 was examined. Dose-response estimates were similar to calendar-year-based results with elevated risk for dose-old, but not when film badge readings were weekly before 1957. Complementary results showed increasing risk with older hire ages and earlier birth cohorts, since workers hired after age 45 were born before 1915, and dose-young and dose-old were distributed differently by birth cohorts. Risks were generally higher for smokingrelated than non-smoking-related cancers. It was difficult to single out specific variables associated with elevated cancer mortality because of: (1) birth cohort differences in hire age and mortality experience completeness, and (2) time-period differences in working conditions, dose potential, and exposure assessment. This research demonstrated the utility and versatility of the age-based approach.« less

On the suitability of ultrathin detectors for absorbed dose assessment in the presence of high-density heterogeneities.

PubMed

Bueno, M; Carrasco, P; Jornet, N; Muñoz-Montplet, C; Duch, M A

2014-08-01

The aim of this study was to evaluate the suitability of several detectors for the determination of absorbed dose in bone. Three types of ultrathin LiF-based thermoluminescent dosimeters (TLDs)-two LiF:Mg,Cu,P-based (MCP-Ns and TLD-2000F) and a (7)Li-enriched LiF:Mg,Ti-based (MTS-7s)-as well as EBT2 Gafchromic films were used to measure percentage depth-dose distributions (PDDs) in a water-equivalent phantom with a bone-equivalent heterogeneity for 6 and 18 MV and a set of field sizes ranging from 5 x 5 cm2 to 20 x 20 cm2. MCP-Ns, TLD-2000F, MTS-7s, and EBT2 have active layers of 50, 20, 50, and 30 μm, respectively. Monte Carlo (MC) dose calculations (PENELOPE code) were used as the reference and helped to understand the experimental results and to evaluate the potential perturbation of the fluence in bone caused by the presence of the detectors. The energy dependence and linearity of the TLDs' response was evaluated. TLDs exhibited flat energy responses (within 2.5%) and linearity with dose (within 1.1%) within the range of interest for the selected beams. The results revealed that all considered detectors perturb the electron fluence with respect to the energy inside the bone-equivalent material. MCP-Ns and MTS-7s underestimated the absorbed dose in bone by 4%-5%. EBT2 exhibited comparable accuracy to MTS-7s and MCP-Ns. TLD-2000F was able to determine the dose within 2% accuracy. No dependence on the beam energy or field size was observed. The MC calculations showed that a[Formula: see text] thick detector can provide reliable dose estimations in bone regardless of whether it is made of LiF, water or EBT's active layer material. TLD-2000F was found to be suitable for providing reliable absorbed dose measurements in the presence of bone for high-energy x-ray beams.

Girl Scouts and Subject Matter Experts: What’s the Connection?

NASA Astrophysics Data System (ADS)

Harman, Pamela; Girls Scouts of Northern California, Girl Scouts USA, Astronomical Society of the Pacifica, Univeristy of Arizona, and ARIES Scientific.

2018-01-01

Reaching for the Stars: NASA Science for Girl Scouts (Girl Scout Stars) fosters interaction between Girl Scouts and NASA Subject Matter Experts (SMEs), disseminates NASA STEM education-related resources, and engages Girl Scouts in NASA science and programs through space science badges and summer camps.A space science badge is in development for each of the six levels of Girl Scouts: Daisies, Grades K – 1; Brownies, Grades 2 -3; Juniors, Grades 4 -5; Cadettes, Grades 6 -8; Seniors, Grades 9 -10; and Ambassadors, Grades 11 -12. Indirectly, SMEs will reach tens of thousands of girls through the badges. SETI Institute SMEs Institute and SME Co-Is located at ARIES Scientific, Astronomical Society of the Pacific, University of Arizona, and Girl Scouts of Northern California developed and modified astronomy activities for the Girl Scouts USA badge writers to finesse into the Girl Scout formats. Revisions are reviewed by SMEs for accuracy. Each badge includes a step option that encourages girls to connect with SMEs, and recommendations for volunteers.A total of 127 girls from 31 states and the District of Columbia attendedTotal Eclipse Destination Camps at three locations. SMEs led activities and tours, inspiring girls to consider STEM careers. University of Arizona (U of A) SMEs lead Astronomy Camp for Volunteers, enabling volunteers to lead and inspire Girl Scouts in their respective Girl Scout Councils. A Destination Camp for Girl Scouts was also held at U of A. Girls experience authentic astronomy, learning how to collect and analyze data.Eleven teams comprised of two Girl Scouts, a volunteer or Council Staff, and an amateur astronomer attended Astronomy Club Camp, held at NASA GSFC. SMEs delivered science content. The girls will lead the formation of astronomy clubs in their councils, and will train their successors. SMEs will present and coach the clubs during monthly webinars.This presentation will highlight success and discuss lessons learned that are applicable

Japan and the Soviet Threat: Perceptions and Reactions.

DTIC Science & Technology

1983-12-01

s...nce the late 1970’s. This _training cannot but help elevate the defense readiness posture of Japan and based on the scenarios being exercised , the...supersonic low flyers, can be easily jammed, and are virtually unprotected (as are Japan’s air bases ). Though work is underway to improve BADGE, it will...opposition to Japanese plans in East Asia, Japan moved to improve its position by concluding a Neutrality Pact with le. .the USSR (1941). .5 The Soviets

Thermoluminescent dosimetry in electron beams: energy dependence.

PubMed

Robar, V; Zankowski, C; Olivares Pla, M; Podgorsak, E B

1996-05-01

The response of thermoluminescent dosimeters to electron irradiations depends on the radiation dose, mean electron energy at the position of the dosimeter in phantom, and the size of the dosimeter. In this paper the semi-empirical expression proposed by Holt et al. [Phys. Med. Biol. 20, 559-570 (1975)] is combined with the calculated electron dose fraction to determine the thermoluminescent dosimetry (TLD) response as a function of the mean electron energy and the dosimeter size. The electron and photon dose fractions, defined as the relative contributions of electrons and bremsstrahlung photons to the total dose for a clinical electron beam, are calculated with Monte Carlo techniques using EGS4. Agreement between the calculated and measured TLD response is very good. We show that the considerable reduction in TLD response per unit dose at low electron energies, i.e., at large depths in phantom, is offset by an ever-increasing relative contribution of bremsstrahlung photons to the total dose of clinical electron beams. This renders the TLD sufficiently reliable for dose measurements over the entire electron depth dose distribution despite the dependence of the TLD response on electron beam energy.

Upper-Bound Radiation Dose Assessment for Military Personnel at McMurdo Station, Antarctica, between 1962 and 1979, Revision 1

DTIC Science & Technology

2016-07-29

using Equation 2 (DTRA, 2010, ED01): Dmonitor highest average HT TLD D = (2) where: TLDhighest = Highest TLD measurement during environmental...the processing of administrative claims or litigation. For use by Agency officials, employees, and authorized contractors . ROUTINE USES

Absorbed Dose Determination Using Experimental and Analytical Predictions of X-Ray Spectra

NASA Technical Reports Server (NTRS)

Edwards, D. L.; Carruth, Ralph (Technical Monitor)

2001-01-01

Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the U.S. Space Shuttle. This series of experiments was named the international space welding experiment (ISWE). The hardware associated with the ISWE was leased to NASA by the Paton Welding Institute (PWI) in Ukraine for ground-based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used thermoluminescence dosimeters (TLD's) shielded with material currently used by astronauts during extravehicular activities to measure the radiation dose. The TLD's were exposed to x-ray radiation generated by operation of the ISWE in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure, then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the ISWE in-vacuum electron beam welding tool. The calculated absorbed dose

Absorbed dose determination using experimental and analytical predictions of x-ray spectra

NASA Astrophysics Data System (ADS)

Edwards, David Lee

1999-10-01

Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate radiation shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) to measure the radiation dose. The TLD's were exposed to x- ray radiation generated by operation of the ISWE in- vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during

Characterisation of mega-voltage electron pencil beam dose distributions: viability of a measurement-based approach.

PubMed

Barnes, M P; Ebert, M A

2008-03-01

The concept of electron pencil-beam dose distributions is central to pencil-beam algorithms used in electron beam radiotherapy treatment planning. The Hogstrom algorithm, which is a common algorithm for electron treatment planning, models large electron field dose distributions by the superposition of a series of pencil beam dose distributions. This means that the accurate characterisation of an electron pencil beam is essential for the accuracy of the dose algorithm. The aim of this study was to evaluate a measurement based approach for obtaining electron pencil-beam dose distributions. The primary incentive for the study was the accurate calculation of dose distributions for narrow fields as traditional electron algorithms are generally inaccurate for such geometries. Kodak X-Omat radiographic film was used in a solid water phantom to measure the dose distribution of circular 12 MeV beams from a Varian 21EX linear accelerator. Measurements were made for beams of diameter, 1.5, 2, 4, 8, 16 and 32 mm. A blocked-field technique was used to subtract photon contamination in the beam. The "error function" derived from Fermi-Eyges Multiple Coulomb Scattering (MCS) theory for corresponding square fields was used to fit resulting dose distributions so that extrapolation down to a pencil beam distribution could be made. The Monte Carlo codes, BEAM and EGSnrc were used to simulate the experimental arrangement. The 8 mm beam dose distribution was also measured with TLD-100 microcubes. Agreement between film, TLD and Monte Carlo simulation results were found to be consistent with the spatial resolution used. The study has shown that it is possible to extrapolate narrow electron beam dose distributions down to a pencil beam dose distribution using the error function. However, due to experimental uncertainties and measurement difficulties, Monte Carlo is recommended as the method of choice for characterising electron pencil-beam dose distributions.

Changes in intrinsic functional connectivity and group relevant salience: The case of sport rivalry.

PubMed

Moradi, Zargol; Mantini, Dante; Yankouskaya, Alla; Hewstone, Miles; Humphreys, Glyn W

2017-08-14

Studies have shown that attending to salient group relevant information could increase the BOLD activity across distributed neural networks. However, it is unclear how attending to group relevant information changes the functional connectivity across these networks. We investigated this issue combining resting states and task-based fMRI experiment. The task involved football fans learning associations between arbitrary geometric shapes and the badges of in-group, the rival and the neutral football teams. Upon learning, participants viewed different badge/shape pairs and their task was to judge whether the viewed pair was a match or a mismatch. For whole brain analyses increased activity was found in the IFG, DLPFC, AI, fusiform gyrus, precuneus and pSTS (all in the left hemisphere) for the rival over the in-group mismatch. Further, the ROI analyses revealed larger beta-values for the rival badge in the left pSTS, left AI and the left IFG. However, larger beta-values were found in the left pSTS and the left IFG (but not AI) for the in-group shape. The intrinsic functional connectivity analyses revealed that compare to the pre-task, post task functional connectivity was decreased between the left DLPFC and the left AI. In contrast, it was increased between the left IFG and the left AI and this was correlated with the difference in RT for the rival vs. in-group team. Our findings suggest that attending to group relevant information differentially affects the strength of functional coupling in attention networks and this can be explained by the saliency of the group relevant information. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed Central

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

2014-01-01

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

6S Return Samples: Assessment of Air Quality in the International Space Station (ISS) Based on Solid Sorbent Air Sampler (SSAS) and Formaldehyde Monitoring Kit (FMK) Analyses

NASA Technical Reports Server (NTRS)

James, John T.

2004-01-01

The toxicological assessments of SSAS and FMK analytical results are reported. Analytical methods have not changed from earlier reports. Surrogate standard recoveries from the SSAS tubes were 66-76% for 13C-acetone, 85-96% for fluorobenzene, and 73-89% for chlorobenzene. Post-flight flows were far below pre-flight flows and an investigation of the problem revealed that the reduced flow was caused by a leak at the interface of the pump inlet tube and the pump head. This resulted in degradation of pump efficiency. Further investigation showed that the problem occurred before the SSAS was operated on orbit and that use of the post-flight flows yielded consistent and useful results. Recoveries from formaldehyde control badges were 86 to 104%. The two general criteria used to assess air quality are the total-non-methane-volatile organic hydrocarbons (NMVOCs) and the total T-value (minus the CO2 and formaldehyde contributions). The T values will not be reported for these data due to the flow anomaly. Control of atmospheric alcohols is important to the water recovery system engineers, hence total alcohols (including acetone) are also shown for each sample. Octafluoropropane (OFP) is not efficiently trapped by the sorbents used in the SSAS. Because formaldehyde is quantified from sorbent badges, its concentration is also listed separately. These five indices of air quality are summarized.

DOE`s nation-wide system for access control can solve problems for the federal government

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

Callahan, S.; Tomes, D.; Davis, G.

1996-07-01

The U.S. Department of Energy`s (DOE`s) ongoing efforts to improve its physical and personnel security systems while reducing its costs, provide a model for federal government visitor processing. Through the careful use of standardized badges, computer databases, and networks of automated access control systems, the DOE is increasing the security associated with travel throughout the DOE complex, and at the same time, eliminating paperwork, special badging, and visitor delays. The DOE is also improving badge accountability, personnel identification assurance, and access authorization timeliness and accuracy. Like the federal government, the DOE has dozens of geographically dispersed locations run by manymore » different contractors operating a wide range of security systems. The DOE has overcome these obstacles by providing data format standards, a complex-wide virtual network for security, the adoption of a standard high security system, and an open-systems-compatible link for any automated access control system. If the location`s level of security requires it, positive visitor identification is accomplished by personal identification number (PIN) and/or by biometrics. At sites with automated access control systems, this positive identification is integrated into the portals.« less

Bisphenols, Benzophenones, and Bisphenol A Diglycidyl Ethers in Textiles and Infant Clothing.

PubMed

Xue, Jingchuan; Liu, Wenbin; Kannan, Kurunthachalam

2017-05-02

Little is known with regard to the occurrence of potentially toxic chemicals in textiles and clothes. In this study, 77 textiles and infant clothing pieces were analyzed for the determination of bisphenols including bisphenol A (BPA) and bisphenol S (BPS), benzophenones, bisphenol A diglycidyl ethers (BADGEs), and novolac glycidyl ethers (NOGEs). BPA and BPS occurred in 82% and 53% of the textile samples, respectively, and at mean concentrations of 366 and 15 ng/g, respectively. Benzophenone-3 (BP3) occurred in 70% of the samples at a mean concentration of 11.3 ng/g. Among 11 BADGEs and NOGEs analyzed, BFDGE was the predominant compound, with a mean concentration of 13.6 ng/g. Concentrations of target chemicals were assessed by fabric type, color, and uses. Socks contained the highest concentrations of BPA (mean: 1810 ng/g) with concentrations as high as 13 300 ng/g in a 97% polyester fabric marketed for infants. Calculated dermal exposure dose to BPA by infants via textiles was as high as 7280 pg/kg BW/d. This is the first study to report the occurrence of, and exposure to, BPA, BPS, BADGEs, and NOGEs in textiles and clothing.

Verification of calculated skin doses in postmastectomy helical tomotherapy.

PubMed

Ito, Shima; Parker, Brent C; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth

2011-10-01

To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi·Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. The mean difference and standard error of the mean difference between measurement and calculation for the scar measurements was -1.8% ± 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% ± 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% ± 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%. Copyright © 2011 Elsevier Inc. All rights reserved.

Verification of Calculated Skin Doses in Postmastectomy Helical Tomotherapy

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

Ito, Shima; Parker, Brent C., E-mail: bcparker@marybird.com; Mary Bird Perkins Cancer Center, Baton Rouge, LA

2011-10-01

Purpose: To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). Methods and Materials: In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi.Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. Results: The mean difference and standard errormore » of the mean difference between measurement and calculation for the scar measurements was -1.8% {+-} 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% {+-} 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% {+-} 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. Conclusions: The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%.« less

A Dosimetry Study of Deuterium-Deuterium Neutron Generator-based In Vivo Neutron Activation Analysis.

PubMed

Sowers, Daniel; Liu, Yingzi; Mostafaei, Farshad; Blake, Scott; Nie, Linda H

2015-12-01

A neutron irradiation cavity for in vivo neutron activation analysis (IVNAA) to detect manganese, aluminum, and other potentially toxic elements in human hand bone has been designed and its dosimetric specifications measured. The neutron source is a customized deuterium-deuterium neutron generator that produces neutrons at 2.45 MeV by the fusion reaction 2H(d, n)3He at a calculated flux of 7 × 10(8) ± 30% s(-1). A moderator/reflector/shielding [5 cm high density polyethylene (HDPE), 5.3 cm graphite and 5.7 cm borated (HDPE)] assembly has been designed and built to maximize the thermal neutron flux inside the hand irradiation cavity and to reduce the extremity dose and effective dose to the human subject. Lead sheets are used to attenuate bremsstrahlung x rays and activation gammas. A Monte Carlo simulation (MCNP6) was used to model the system and calculate extremity dose. The extremity dose was measured with neutron and photon sensitive film badges and Fuji electronic pocket dosimeters (EPD). The neutron ambient dose outside the shielding was measured by Fuji NSN3, and the photon dose was measured by a Bicron MicroREM scintillator. Neutron extremity dose was calculated to be 32.3 mSv using MCNP6 simulations given a 10-min IVNAA measurement of manganese. Measurements by EPD and film badge indicate hand dose to be 31.7 ± 0.8 mSv for neutrons and 4.2 ± 0.2 mSv for photons for 10 min; whole body effective dose was calculated conservatively to be 0.052 mSv. Experimental values closely match values obtained from MCNP6 simulations. These are acceptable doses to apply the technology for a manganese toxicity study in a human population.

A TLD-based ten channel system for the spectrometry of bremsstrahlung generated by laser-matter interaction

NASA Astrophysics Data System (ADS)

Horst, Felix; Fehrenbacher, Georg; Radon, Torsten; Kozlova, Ekaterina; Rosmej, Olga; Czarnecki, Damian; Schrenk, Oliver; Breckow, Joachim; Zink, Klemens

2015-05-01

This work presents a thermoluminescence dosimetry based method for the measurement of bremsstrahlung spectra in the energy range from 30 keV to 100 MeV, resolved in ten different energy intervals and for the photon ambient dosimetry in ultrashort pulsed radiation fields as e.g. generated during operation of the PHELIX laser at the GSI Helmholtzzentrum für Schwerionenforschung. The method is a routine-oriented development by application of a multi-filter technique. The data analysis takes around 1 h. The spectral information is obtained by the unfolding of the response of ten thermoluminescence dosimeters with absorbers of different materials and thicknesses arranged as a stack each with a different response function to photon radiation. These response functions were simulated by the use of the Monte Carlo code FLUKA. An algorithm was developed to unfold bremsstrahlung spectra from the readings of the ten dosimeters. The method has been validated by measurements at a clinical electron linear accelerator (6 MV and 18 MV bremsstrahlung). First measurements at the PHELIX laser system were carried out in December 2013 and January 2014. Spectra with photon energies up to 10 MeV and mean energies up to 420 keV were observed at laser-intensities around 1019 W /cm2 on a titanium foil target. The measurement results imply that the steel walls of the target chamber might be an additional bright x-ray source.

Assessment of Air Quality in the Shuttle and International Space Station (ISS) Based on Samples Returned by STS-105 at the Conclusion of 7A.1

NASA Technical Reports Server (NTRS)

James, John T.

2001-01-01

The toxicological assessment of air samples returned at the end of the STS-105 (7 A.1) flight to the ISS is reported. ISS air samples were taken in August 2001 from the Service Module, FGB, and U.S. Laboratory using grab sample canisters (GSCs) and/or formaldehyde badges. Preflight and end-of-mission samples were obtained from Discovery using GSCs. Analytical methods have not changed from earlier reports, and surrogate standard recoveries were 64-115%. Pressure tracking indicated no leaks in the canisters.

Comparison of thermoluminescence response of different sized Ge-doped flat fibers as a dosimeter

NASA Astrophysics Data System (ADS)

Begum, Mahfuza; Mizanur Rahman, A. K. M.; Abdul-Rashid, H. A.; Yusoff, Z.; Mat-Sharif, K. A.; Zulkifli, M. I.; Muhamad-Yasin, S. Z.; Ung, N. M.; Kadir, A. B. A.; Amin, Y. M.; Bradley, D. A.

2015-11-01

Prime dosimetric properties, including dose-response, linearity with dose, energy response, fading and threshold doses were investigated for three different dimension Ge-doped flat fibers. The results of measurement were also compared with two of the more commonly used standard TLD media, TLD-100 (LiF:Mg,Ti-7.5%6LiF) and TLD-700 (7LiF:Mg,Ti-99.9%7LiF) chips. The flat cross-section samples (60×180) μm2, (100×350) μm2 and (200×750) μm2 were fabricated using the Modified Chemical Vapor Deposition (MCVD) process and pulled from the same "preform." In the study, all flat fiber samples provided good linear dose-response for the photon and electron beams generated using a medical linear accelerator (LINAC), for doses in the range 0.5-8 Gy. Among the samples, the smallest dimension flat fiber provided the best response, with a sensitivity of some 61% and 54%, respectively of that of the TLD-100 and TLD-700 chips. The energy responses of the samples were studied for various photon (6 MV, 10 MV) and electron (6 MeV, 9 MeV) beam energies. TL fading of around 20% was observed over a period of thirty (30) days. These favorable TL characteristics point towards promising development of Ge-doped flat fibers for use in radiotherapy dosimetry.

Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube.

PubMed

Gagliardi, F M; Roxby, K J; Engström, P E; Crosbie, J C

2009-06-21

Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 +/- 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube

NASA Astrophysics Data System (ADS)

Gagliardi, F. M.; Roxby, K. J.; Engström, P. E.; Crosbie, J. C.

2009-06-01

Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 ± 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

Biokinetics of radiolabeled Iodophenylpentadecanoic acid (I-123-IPPA) and thallium-201 in a rabbit model of chronic myocardial infarction measured using a series of thermoluminescent dosimeters

NASA Astrophysics Data System (ADS)

Medich, David Christopher

1997-09-01

The biokinetics of Iodophenylpentadecanoic acid (123I-IPPA) during a chronic period of myocardial infarction were determined and compared to 201Tl. IPPA was assessed as a perfusion and metabolic tracer in the scintigraphic diagnosis of coronary artery disease. The myocardial clearance kinetics were measured by placing a series of thermoluminescent dosimeters (TLDs) on normal and infarcted tissue to measure the local myocardial activity content over time. The arterial blood pool activity was fit to a bi-exponential function for 201Tl and a tri-exponential function for 123I-IPPA to estimate the left ventricle contribution to TLD response. At equilibrium, the blood pool contribution was estimated experimentally to be less than 5% of the total TLD response. The method was unable to resolve the initial uptake of the imaging agent due in part to the 2 minute TLD response integration time and in part to the 30 second lag time for the first TLD placement. A noticeable disparity was observed between the tracer concentrations of IPPA in normal and ischemic tissue of approximately 2:1. The fitting parameters (representing the biokinetic eigenvalue rate constants) were related to the fundamental rate constants of a recycling biokinetic model. The myocardial IPPA content within normal tissue was elevated after approximately 130 minutes post injection. This phenomenon was observed in all but one (950215) of the IPPA TLD kinetics curves.

Targeting Radiation Therapy for Developing Dendritic Cell Based Immunotherapy of Metastatic Prostate Cancer

DTIC Science & Technology

2006-01-01

SSD) was used. Thermo luminescence dosimetry ( TLD ) was used to a midline phantom within the jig and was the basis for all dose calculations. 23 c...vitro and in vivo (7 Bellone et al 1997, 8 Sauter et al 2000, 9 Joke et al 2000). Once the DCs are activated, they express the lymphoid homing receptor...the proliferation and 5 differentiation of a variety of hematopoietic cells including DCs in vivo , both in mice and in humans (13 Shurin et al 1988

Spectroscopic and molecular modeling approaches to investigate the interaction of bisphenol A, bisphenol F and their diglycidyl ethers with PPARα.

PubMed

Zhang, Jie; Zhang, Tiehua; Guan, Tianzhu; Ruan, Ping; Ren, Dayong; Dai, Weichang; Yu, Hansong; Li, Tiezhu

2017-08-01

A fluorescence polarization (FP) assay for the simultaneous determination of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) was developed. The method was based on the competition between bisphenols (BPs) and fluorescein-labeled dexamethasone derivative (Dex-fl) for mouse peroxisome proliferator-activated receptor α ligand binding domain (mPPARα-LBD). A recombinant soluble protein derivative mPPARα-LBD* was prepared, then in vitro binding of 4 BPs to mPPARα-LBD* was investigated. Fluorescence polarization assay showed that these compounds exhibited different binding potencies with mPPARα-LBD*. Additionally, molecular dynamics simulations were performed to further understand the mechanism of BPs binding affinity for mPPARα-LBD*. Docking results elucidated that the driving forces for the binding of BPs to mPPARα-LBD* were predominantly dependent on hydrophobic and hydrogen-bonding interactions. Comparison of the calculated binding energies vs. experimental binding affinities yielded a good correlation (R 2  = 0.7258). The proposed method has potential for multi-residue detection of BPA, BPF, BADGE, and BFDGE. Copyright © 2017 Elsevier Ltd. All rights reserved.

Insights From the Development of an Environmental Science Professional Development Field Course for Undergraduates from Two-Year and Four-Year Colleges.

NASA Astrophysics Data System (ADS)

Schmidt, C. M.; Hall, S. R.; Walker, B.; Paul, J.

2017-12-01

Existing STEM retention and diversity programs have identified access to field and professional experiences as critical to helping students identify as scientists, form networks, and gain important skills necessary for employment. This program reimagines the traditional geology field course as a professional development experience for students at 2-year and 4-year institutions interested in environmental careers. Students participate in a summer field course in the Sierra Nevada of California, during which time they complete geology, geomorphology, hydrology, and ecology field projects designed to compliment the curriculum of Environmental Geoscience, Environmental Science, and Environmental Studies programs. During the course students interact with local professionals in the environmental sector and work to earn badges based on the skills demonstrated during field projects. Badges create transparent documentation of skill mastery for students and provide a new way for students to understand and market their skills and competencies to potential employers. We will report on the curriculum development, implementation and assessment of the first cohort of students to participate in the program. Preliminary results of formative and summative assessments and their implications for student success and program design will be addressed.

Assessment of Air Quality in the Shuttle and International Space Station (ISS) Based on Samples Returned by STS-104 at the Conclusion of 7A

NASA Technical Reports Server (NTRS)

James, John T.

2001-01-01

The toxicological assessment of air samples returned at the end of the STS-l04 (7 A) flight to the ISS is reported. ISS air samples were taken in June and July 2001 from the Service Module, FGB, and U.S. Laboratory using grab sample canisters (GSCs) and/or formaldehyde badges. Preflight and end-of-mission samples were obtained from Atlantis using GSCs. Solid sorbent air sampler (SSAS) samples were obtained from the ISS in April, June, and July. Analytical methods have not changed from earlier reports, and all quality control measures were met.

The Role of Teachers' Future Self Guides in Creating L2 Development Opportunities in Teacher-Led Classroom Discourse: Reclaiming the Relevance of Language Teacher Cognition

ERIC Educational Resources Information Center

Kubanyiova, Magdalena

2015-01-01

Understanding the relationship between teachers' use of language in teacher-led discourse (TLD; Toth, 2008) and opportunities for L2 development is a well-established area of SLA research. This study examines one teacher's role in creating such opportunities in TLD in her EFL classes in a state secondary school by examining the inner resources…

Languaging in Translation Tasks Used in a University Setting: Particular Potential for Student Agency?

ERIC Educational Resources Information Center

Kallkvist, Marie

2013-01-01

This article explores the value of judiciously used first language (L1)-to-second language (L2) translation in meaning-focused, advanced-level academic language education. It examines languaging in the teacher-led discourse (TLD) that arises when translation tasks are used and compares it to languaging during the TLD engendered by 4 other…

Thermoluminescence measurements of neutron dose around a medical linac.

PubMed

Barquero, R; Méndez, R; Iñiguez, M P; Vega, H R; Voytchev, M

2002-01-01

The photoncutron ambient dose around a 18 MV medical electron lineal accelerator has been measured with LiF:Mg,Ti chips of 3 x 3 x 1 mm inside moderating spheres. During the measurements a water phantom was irradiated in a field of 40 x 40 cm2. Two methods have been considered for comparison. In the first, a TLD-600/TLD-700 pair at the centre of a 25 cm diameter paraffine sphere was used, with the system behaving as a rem meter. In the second method, TLD-600/TLD-700 pairs, bare and at the centre of 7.6, 12.7, 20.3, 25.4, and 30.5 cm diameter polyethylene Bonner spheres were used to obtain the neutron spectrum. This was unfolded using the BUNKIUT code with the SPUNIT algorithm and the UTA4 and ARKI response functions. The neutron dose was followed by multiplying the unfolded neutron spectrum by the ambient dose equivalent to neutron fluence conversion factors. Both methods result in 0.5 mSv x Gy(-1) m away from the isocentre.

In vivo dose verification of IMRT treated head and neck cancer patients.

PubMed

Engström, Per E; Haraldsson, Pia; Landberg, Torsten; Sand Hansen, Hanne; Aage Engelholm, Svend; Nyström, Håkan

2005-01-01

An independent in vivo dose verification procedure for IMRT treatments of head and neck cancers was developed. Results of 177 intracavitary TLD measurements from 10 patients are presented. The study includes data from 10 patients with cancer of the rhinopharynx or the thyroid treated with dynamic IMRT. Dose verification was performed by insertion of a flexible naso-oesophageal tube containing TLD rods and markers for EPID and simulator image detection. Part of the study focussed on investigating the accuracy of the TPS calculations in the presence of inhomogeneities. Phantom measurements and Monte Carlo simulations were performed for a number of geometries involving lateral electronic disequilibrium and steep density shifts. The in vivo TLD measurements correlated well with the predictions of the treatment planning system with a measured/calculated dose ratio of 1.002+/-0.051 (1 SD, N=177). The measurements were easily performed and well tolerated by the patients. We conclude that in vivo intracavitary dosimetry with TLD is suitable and accurate for dose determination in intensity-modulated beams.

Two-dimensional dosimetry of radiotherapeutical proton beams using thermoluminescence foils.

PubMed

Czopyk, L; Klosowski, M; Olko, P; Swakon, J; Waligorski, M P R; Kajdrowicz, T; Cuttone, G; Cirrone, G A P; Di Rosa, F

2007-01-01

In modern radiation therapy such as intensity modulated radiation therapy or proton therapy, one is able to cover the target volume with improved dose conformation and to spare surrounding tissue with help of modern measurement techniques. Novel thermoluminescence dosimetry (TLD) foils, developed from the hot-pressed mixture of LiF:Mg,Cu,P (MCP TL) powder and ethylene-tetrafluoroethylene (ETFE) copolymer, have been applied for 2-D dosimetry of radiotherapeutical proton beams at INFN Catania and IFJ Krakow. A TLD reader with 70 mm heating plate and CCD camera was used to read the 2-D emission pattern of irradiated foils. The absorbed dose profiles were evaluated, taking into account correction factors specific for TLD such as dose and energy response. TLD foils were applied for measuring of dose distributions within an eye phantom and compared with predictions obtained from the MCNPX code and Eclipse Ocular Proton Planning (Varian Medical Systems) clinical radiotherapy planning system. We demonstrate the possibility of measuring 2-D dose distributions with point resolution of about 0.5 x 0.5 mm(2).

MAGIC-f Gel in Nuclear Medicine Dosimetry: study in an external beam of Iodine-131

NASA Astrophysics Data System (ADS)

Schwarcke, M.; Marques, T.; Garrido, C.; Nicolucci, P.; Baffa, O.

2010-11-01

MAGIC-f gel applicability in Nuclear Medicine dosimetry was investigated by exposure to a 131I source. Calibration was made to provide known absorbed doses in different positions around the source. The absorbed dose in gel was compared with a Monte Carlo Simulation using PENELOPE code and a thermoluminescent dosimetry (TLD). Using MRI analysis for the gel a R2-dose sensitivity of 0.23 s-1Gy-1was obtained. The agreement between dose-distance curves obtained with Monte Carlo simulation and TLD was better than 97% and for MAGIC-f and TLD was better than 98%. The results show the potential of polymer gel for application in nuclear medicine where three dimensional dose distribution is demanded.

Experimental verification of bremsstrahlung production and dosimetry predictions for 15.5 MeV electrons

NASA Astrophysics Data System (ADS)

Sanford, T. W. L.; Beutler, D. E.; Halbleib, J. A.; Knott, D. P.

1991-12-01

The radiation produced by a 15.5-MeV monoenergetic electron beam incident on optimized and nonoptimized bremsstrahlung targets is characterized using the ITS Monte Carlo code and measurements with equilibrated and nonequilibrated TLD dosimetry. Comparisons between calculations and measurements verify the calculations and demonstrate that the code can be used to predict both bremsstrahlung production and TLD response for radiation fields that are characteristic of those produced by pulsed simulators of gamma rays. The comparisons provide independent confirmation of the validity of the TLD calibration for photon fields characteristic of gamma-ray simulators. The empirical Martin equation, which is often used to calculate radiation dose from optimized bremsstrahlung targets, is examined, and its range of validity is established.

Two-photon luminescence lifetime imaging microscopy (LIM) to follow up cell metabolism and oxygen consumption during theranostic applications

NASA Astrophysics Data System (ADS)

Rück, A.; Breymayer, J.; Lilge, L.; Mandel, A.; Schäfer, P.; von Einem, B.; von Arnim, C.; Kalinina, S.

2018-02-01

A common property during tumor development is altered energy metabolism, which could lead to a switch from oxidative phosphorylation and glycolysis. The impact of this switch for theranostic applications could be significant. Interestingly altered metabolism could be correlated with a change in the fluorescence lifetimes of both NAD(P)H and FAD. However, as observed in a variety of investigations, the situation is complex and the result is influenced by parameters like oxidative stress, pH or viscosity. Besides metabolism, oxygen levels and consumption has to be taken into account in order to understand treatment responses. For this, correlated imaging of phosphorescence and fluorescence lifetime parameters has been investigated by us and used to observe metabolic markers simultaneously with oxygen concentrations. The technique is based on time correlated single photon counting to detect the fluorescence lifetime of NAD(P)H and FAD by FLIM and the phosphorescence lifetime of newly developed phosphors and photosensitizers by PLIM. For this, the photosensitizer TLD1433 from Theralase, which is based on a ruthenium (II) coordination complex, was used. TLD1433 which acts as a redox indicator was mainly found in cytoplasmatic organelles. The most important observation was that TLD1433 can be used as a phosphor to follow up local oxygen concentration and consumption during photodynamic therapy. Oxygen consumption was accompanied by a change in cell metabolism, observed by simultaneous FLIM/PLIM. The combination of autofluorescence-FLIM and phosphor-PLIM in luminescence lifetime microscopy provides new insights in light induced reactions.

Experimental investigation of the 100 keV X-ray dose response of the high-temperature thermoluminescence in LiF:Mg,Ti (TLD-100): theoretical interpretation using the unified interaction model.

PubMed

Livingstone, J; Horowitz, Y S; Oster, L; Datz, H; Lerch, M; Rosenfeld, A; Horowitz, A

2010-03-01

The dose response of LiF:Mg,Ti (TLD-100) chips was measured from 1 to 50,000 Gy using 100 keV X rays at the European Synchroton Radiation Facility. Glow curves were deconvoluted into component glow peaks using a computerised glow curve deconvolution (CGCD) code based on first-order kinetics. The normalised dose response, f(D), of glow peaks 4 and 5 and 5b (the major components of composite peak 5), as well as peaks 7 and 8 (two of the major components of the high-temperature thermoluminescence (HTTL) at high levels of dose) was separately determined and theoretically interpreted using the unified interaction model (UNIM). The UNIM is a nine-parameter model encompassing both the irradiation/absorption stage and the thermally induced relaxation/recombination stage with an admixture of both localised and delocalised recombination mechanisms. The effects of radiation damage are included in the present modelling via the exponential removal of luminescent centres (LCs) at high dose levels. The main features of the experimentally measured dose response are: (i) increase in f(D)(max) with glow peak temperature, (ii) increase in D(max) (the dose level at which f(D)(max) occurs) with increasing glow peak temperature, and (iii) decreased effects of radiation damage with increasing glow peak temperature. The UNIM interpretation of this behaviour requires both strongly decreasing values of ks (the relative contribution of localised recombination) as a function of glow peak temperature and, as well, significantly different values of the dose-filling constants of the trapping centre (TC) and LC for peaks 7 and 8 than those used for peaks 4 and 5. This suggests that different TC/LC configurations are responsible for HTTL. The relative intensity of peak 5a (a low-temperature satellite of peak 5 arising from localised recombination) was found to significantly increase at higher dose levels due to preferential electron and hole population of the trapping/recombination complex giving

Implementation of alanine/EPR as transfer dosimetry system in a radiotherapy audit programme in Belgium.

PubMed

Schaeken, B; Cuypers, R; Lelie, S; Schroeyers, W; Schreurs, S; Janssens, H; Verellen, D

2011-04-01

A measurement procedure based on alanine/electron paramagnetic resonance (EPR) dosimetry was implemented successfully providing simple, stable, and accurate dose-to-water (D(w)) measurements. The correspondence between alanine and ionization chamber measurements in reference conditions was excellent. Alanine/EMR dosimetry might be a valuable alternative to thermoluminescent (TLD) and ionization chamber based measuring procedures in radiotherapy audits. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Ultrastructure of cholinergic neurons in the laterodorsal tegmental nucleus of the rat: interaction with catecholamine fibers.

PubMed

Kubota, Y; Leung, E; Vincent, S R

1992-01-01

The ultrastructure of choline acetyltransferase (ChAT)-immunoreactive neurons in the laterodorsal tegmental nucleus (TLD) of the rat was investigated by immunohistochemical techniques. The immunoreactive neurons were medium to large in size, with a few elongated dendrites, contained well-developed cytoplasm, and a nucleus with deep infoldings. They received many nonimmunoreactive, mostly asymmetric synaptic inputs on their soma and dendrites. ChAT-immunoreactive, usually myelinated, axons were occasionally seen in TLD. Only one immunoreactive axon terminal was observed within TLD, and it made synaptic contact with a nonimmunoreactive neuronal perikaryon. The synaptic interactions between ChAT-immunoreactive neurons and tyrosine hydroxylase (TH)-immunoreactive fibers in the TLD were investigated with a double immunohistochemical staining method. ChAT-immunoreactivity detected with a beta-galactosidase method was light blue-green in the light microscope and formed dot-like electron dense particles at the electron microscopic level. TH-immunoreactivity, visualized with a nickel-enhanced immunoperoxidase method, was dark blue-black in the light microscope and diffusely opaque in the electron microscope. Therefore, the difference between these two kinds of immunoreactivity could be quite easily distinguished at both light and electron microscopic levels. In the light microscope, TH-positive fibers were often closely apposed to ChAT-immunoreactive cell bodies and dendrites in TLD. In the electron microscope, the cell soma and proximal dendrites of ChAT-immunoreactive neurons received synaptic contacts from TH-immunoreactive axon terminals. These results provide a morphological basis for catecholaminergic regulation of the cholinergic reticular system.

Upregulation of Interleukin 7 Receptor Alpha and Programmed Death 1 Marks an Epitope-Specific CD8+ T-Cell Response That Disappears following Primary Epstein-Barr Virus Infection▿ †

PubMed Central

Sauce, Delphine; Larsen, Martin; Abbott, Rachel J. M.; Hislop, Andrew D.; Leese, Alison M.; Khan, Naeem; Papagno, Laura; Freeman, Gordon J.; Rickinson, Alan B.

2009-01-01

In immunocompetent individuals, the stability of the herpesvirus-host balance limits opportunities to study the disappearance of a virus-specific CD8+ T-cell response. However, we noticed that in HLA-A*0201-positive infectious mononucleosis (IM) patients undergoing primary Epstein-Barr virus (EBV) infection, the initial CD8 response targets three EBV lytic antigen-derived epitopes, YVLDHLIVV (YVL), GLCTLVAML (GLC), and TLDYKPLSV (TLD), but only the YVL and GLC reactivities persist long-term; the TLD response disappears within 10 to 27 months. While present, TLD-specific cells remained largely indistinguishable from YVL and GLC reactivities in many phenotypic and functional respects but showed unique temporal changes in two markers of T-cell fate, interleukin 7 receptor alpha (IL-7Rα; CD127) and programmed death 1 (PD-1). Thus, following the antigen-driven downregulation of IL-7Rα seen on all populations in acute IM, in every case, the TLD-specific population recovered expression unusually quickly post-IM. As well, in four of six patients studied, TLD-specific cells showed very strong PD-1 upregulation in the last blood sample obtained before the cells’ disappearance. Our data suggest that the disappearance of this individual epitope reactivity from an otherwise stable EBV-specific response (i) reflects a selective loss of cognate antigen restimulation (rather than of IL-7-dependent signals) and (ii) is immediately preceded, and perhaps mediated, by PD-1 upregulation to unprecedented levels. PMID:19605492

Upregulation of interleukin 7 receptor alpha and programmed death 1 marks an epitope-specific CD8+ T-cell response that disappears following primary Epstein-Barr virus infection.

PubMed

Sauce, Delphine; Larsen, Martin; Abbott, Rachel J M; Hislop, Andrew D; Leese, Alison M; Khan, Naeem; Papagno, Laura; Freeman, Gordon J; Rickinson, Alan B

2009-09-01

In immunocompetent individuals, the stability of the herpesvirus-host balance limits opportunities to study the disappearance of a virus-specific CD8(+) T-cell response. However, we noticed that in HLA-A 0201-positive infectious mononucleosis (IM) patients undergoing primary Epstein-Barr virus (EBV) infection, the initial CD8 response targets three EBV lytic antigen-derived epitopes, YVLDHLIVV (YVL), GLCTLVAML (GLC), and TLDYKPLSV (TLD), but only the YVL and GLC reactivities persist long-term; the TLD response disappears within 10 to 27 months. While present, TLD-specific cells remained largely indistinguishable from YVL and GLC reactivities in many phenotypic and functional respects but showed unique temporal changes in two markers of T-cell fate, interleukin 7 receptor alpha (IL-7Ralpha; CD127) and programmed death 1 (PD-1). Thus, following the antigen-driven downregulation of IL-7Ralpha seen on all populations in acute IM, in every case, the TLD-specific population recovered expression unusually quickly post-IM. As well, in four of six patients studied, TLD-specific cells showed very strong PD-1 upregulation in the last blood sample obtained before the cells' disappearance. Our data suggest that the disappearance of this individual epitope reactivity from an otherwise stable EBV-specific response (i) reflects a selective loss of cognate antigen restimulation (rather than of IL-7-dependent signals) and (ii) is immediately preceded, and perhaps mediated, by PD-1 upregulation to unprecedented levels.

Effects of High Energy Electron Irradiation on a Yttrium Barium(2) Copper(3) Oxygen(7-delta) High Temperature Superconductor

DTIC Science & Technology

1991-09-01

2 2. Dosimetry ............................................. 4 C. OVERVIEW OF EXPERIMENT............................... 5 11. ELECTRON BEAM...From these measurements, the dose was calculated and then compared to a measured dose obtained from TLD dosimetry . Technical 5 problems with the...LINAC precluded TLD dosimetry from being accomplished during the first run and, therefore, was performed on the second run only. After irradiation, a NaI

The Effect of Irradiation on Bone Remodelling and the Structural Integrity of the Vertebral Column

DTIC Science & Technology

1990-01-01

thermoluminescent dosimetry calculations were also used. Seventy-four lithium fluoride thermoluminescent dosimeters ( TLDs ) were selected from 120...and thermoluminescent dosimetry ( TLD ) were used to evaluate the actual doses administered. The TLD analysis was completed with five strips of five...professional help with the dose administration and the dosimetry . And especially to my husband. Kevin, without whose help and encouragement I could not have

A comparative study of the thermoluminescent response to beta irradiation of CVD diamond and LiF dosimeters

NASA Astrophysics Data System (ADS)

Bogani, F.; Borchi, E.; Bruzzi, M.; Leroy, C.; Sciortino, S.

1997-02-01

The thermoluminescent (TL) response of Chemical Vapour Deposited (CVD) diamond films to beta irradiation has been investigated. A numerical curve-fitting procedure, calibrated by means of a set of LiF TLD100 experimental spectra, has been developed to deconvolute the complex structured TL glow curves. The values of the activation energy and of the frequency factor related to each of the TL peaks involved have been determined. The TL response of the CVD diamond films to beta irradiation has been compared with the TL response of a set of LiF TLD100 and TLD700 dosimeters. The results have been discussed and compared in view of an assessment of the efficiency of CVD diamond films in future applications as in vivo dosimeters.

Neutron dosimetric measurements in shuttle and MIR.

PubMed

Reitz, G

2001-06-01

Detector packages consisting of thermoluminescence detectors (TLD), nuclear emulsions and plastic track detectors were exposed at identical positions inside MIR space station and on shuttle flights inside Spacelab and Spacehab during different phases of the solar cycle. The objectives of the investigations are to provide data on charge and energy spectra of heavy ions, and the contribution of events with low-energy deposit (protons, electrons, gamma, etc.) to the dose, as well as the contribution of secondaries, such as nuclear disintegration stars and neutrons. For neutron dosimetry 6LiF (TLD600) and 7LiF (TLD700) chips were used both of which have almost the same response to gamma rays but different response to neutrons. Neutrons in space are produced mainly in evaporation and knock-on processes with energies mainly of 1-10 MeV and up to several 100 MeV, respectively. The energy spectrum undergoes continuous changes toward greater depth in the attenuating material until an equilibrium is reached. In equilibrium, the spectrum is a wide continuum extending down to thermal energies to which the 6LiF is sensitive. Based on the difference of absorbed doses in the 6LiF and 7LiF chips, thermal neutron fluxes from 1 to 2.3 cm-2 s-1 are calculated using the assumption that the maximum induced dose in TLD600 for 1 neutron cm-2 is 1.6 x 10(-10) Gy (Horowitz and Freeman, Nucl. Instr. and Meth. 157 (1978) 393). It is assumed that the flux of high-energy neutrons is at least of that quantity. Tissue doses were calculated taking as a mean ambient absorbed dose per neutron 6 x10(-12) Gy cm2 (for a10 MeV neutron). The neutron equivalent doses for the above-mentioned fluxes are 52 micro Gy d-1 and 120 micro Gy d-1. In recent experiments, a personal neutron dosimeter was integrated into the dosimeter packages. First results of this dosimeter which is based on nuclear track detectors with converter foils are reported. For future measurements, a scintillator counter with

Implementation of a Lateral TBI protocol in a Mexican Cancer Center

NASA Astrophysics Data System (ADS)

Mesa, Francisco; Esquivel, Carlos; Eng, Tony; Papanikolaou, Niko; Sosa, Modesto A.

2008-08-01

The development of a Lateral Total Body Irradiation protocol to be implemented at a High Specialty Medical Unit in Mexico as preparatory regimen for bone marrow transplant and treatment of several lymphomas is presented. This protocol was developed following AAPM specifications and has been validated for application at a cancer care center in United States. This protocol fundamentally focuses on patient care, avoiding instability and discomfort that may be encountered by other treatment regimes. In vivo dose verification with TLD-100 chips for each anatomical region of interest was utilized. TLD-100 chips were calibrated using a 6 MV photon beam for 10-120 cGy. Experimental results show TLD measurements with an error less than 1%. Standard deviations for calculated and measured doses for seven patients have been obtained. Data gathered for different levels of compensation indicate that a 3% measured tolerance level is acceptable. TLD point-dose measurements have been used to verify the dose beyond partial transmission lung blocks. Dose measurements beyond the lung block showed variation about 50% respects to prescribe dose. Midplane doses to the other anatomical sites were less than 2.5% respect of the prescribed dose.

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.

A field evaluation of a piezo-optical dosimeter for environmental monitoring of nitrogen dioxide.

PubMed

Wright, John D; Schillinger, Eric F J; Cazier, Fabrice; Nouali, Habiba; Mercier, Agnes; Beaugard, Charles

2004-06-01

Measurements of 8-hour time-weighted average NO(2) concentrations are reported at 7 different locations in the region of Dunkirk over 5 consecutive days using PiezOptic monitoring badges previously calibrated for the range 0-70 ppb together with data from chemiluminescent analysers in 5 sites (4 fixed and one mobile). The latter facilities also provided data on ozone and NO concentrations and meteorological conditions. Daily averages from the two pairs of badges in different types of sampling cover in each site have been compared with data from the chemiluminescent analysers, and found largely to agree within error margins of +/-30%. Although NO(2) and ozone concentrations were low, rendering detailed discussion impossible, the general features followed expected patterns.

New 2-D dosimetric technique for radiotherapy based on planar thermoluminescent detectors.

PubMed

Olko, P; Marczewska, B; Czopyk, L; Czermak, M A; Klosowski, M; Waligórski, M P R

2006-01-01

At the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ) in Kraków, a two-dimensional (2-D) thermoluminescence (TL) dosimetry system was developed within the MAESTRO (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology) 6 Framework Programme and tested by evaluating 2-D dose distributions around radioactive sources. A thermoluminescent detector (TLD) foil was developed, of thickness 0.3 mm and diameter 60 mm, containing a mixture of highly sensitive LiF:Mg,Cu,P powder and Ethylene TetraFluoroEthylene (ETFE) polymer. Foil detectors were irradiated with (226)Ra brachytherapy sources and a (90)Sr/(90)Y source. 2-D dose distributions were evaluated using a prototype planar (diameter 60 mm) reader, equipped with a 12 bit Charge Coupled Devices (CCD) PCO AG camera, with a resolution of 640 x 480 pixels. The new detectors, showing a spatial resolution better than 0.5 mm and a measurable dose range typical for radiotherapy, can find many applications in clinical dosimetry. Another technology applicable to clinical dosimetry, also developed at IFJ, is the Si microstrip detector of size 95 x 95 mm(2), which may be used to evaluate the dose distribution with a spatial resolution of 120 microm along one direction, in real-time mode. The microstrip and TLD technology will be further improved, especially to develop detectors of larger area, and to make them applicable to some advanced radiotherapy modalities, such as intensity modulated radiotherapy (IMRT) or proton radiotherapy.

Characterization and Comparison of New Concepts in Neutron Detection

DTIC Science & Technology

2010-05-12

because a single detector can be reused many times. The TLDs used in this experiment were typical of those used in the United States Navy for dosimetry ...5 1.5.1 TLD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5.2 Bubble Dosimeters . . . . . . . . . . . . . . . . . . . . 5 1.5.3...67 v List of Figures 1.1 TLD card (left) and holder (right). The four sensitive areas are on the card and contain

SU-E-T-90: Accuracy of Calibration of Lithium-6 and -7 Enriched LiF TLDs for Neutron Measurements in High Energy Radiotherapy

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

Keehan, S; Franich, R; Taylor, M

Purpose: To determine the potential error involved in the interpretation of neutron measurements from medical linear accelerators (linacs) using TLD-600H and TLD-700H if standard AmBe and {sup 252}Cf neutron sources are used for calibration without proper inclusion of neutron energy spectrum information. Methods: The Kerma due to neutrons can be calculated from the energy released by various nuclear interactions (elastic and inelastic scatter, (n,α), (n,p), (n,d), (n,t), (n,2n), etc.). The response of each TLD can be considered the sum of the neutron and gamma components; each proportional to the Kerma. Using the difference between the measured TLD responses and themore » ratio of the calculated Kerma for each material, the neutron component of the response can be calculated. The Monte Carlo code MCNP6 has been used to calculate the neutron energy spectra resulting from photonuclear interactions in a Varian 21EX linac. TLDs have been exposed to the mixed (γ-n) field produced by a linac and AmBe and {sup 252}Cf standard neutron sources. Results: For dosimetry of neutrons from AmBe or {sup 252}Cf sources, assuming TLD-700H insensitivity to neutrons will Result in 10% or 20% overestimation of neutron doses respectively.For dosimetry of neutrons produced in a Varian 21EX, applying a calibration factor derived from a standard AmBe or {sup 252}Cf source will Result in an overestimation of neutron fluence, by as much as a factor of 47.The assumption of TLD-700H insensitivity to neutrons produced by linacs leads to a negligible error due to the extremely high Kerma ratio (600H/700H) of 3000 for the assumed neutron spectrum. Conclusion: Lithium-enriched TLDs calibrated with AmBe and/or {sup 252}Cf neutron sources are not accurate for use under the neutron energy spectrum produced by a medical linear accelerator.« less

Peripheral dose measurements with diode and thermoluminescence dosimeters for intensity modulated radiotherapy delivered with conventional and un-conventional linear accelerator

PubMed Central

Kinhikar, Rajesh; Gamre, Poonam; Tambe, Chandrashekhar; Kadam, Sudarshan; Biju, George; Suryaprakash; Magai, C. S.; Dhote, Dipak; Shrivastava, Shyam; Deshpande, Deepak

2013-01-01

The objective of this paper was to measure the peripheral dose (PD) with diode and thermoluminescence dosimeter (TLD) for intensity modulated radiotherapy (IMRT) with linear accelerator (conventional LINAC), and tomotherapy (novel LINAC). Ten patients each were selected from Trilogy dual-energy and from Hi-Art II tomotherapy. Two diodes were kept at 20 and 25 cm from treatment field edge. TLDs (LiF:MgTi) were also kept at same distance. TLDs were also kept at 5, 10, and 15 cm from field edge. The TLDs were read with REXON reader. The readings at the respective distance were recorded for both diode and TLD. The PD was estimated by taking the ratio of measured dose at the particular distance to the prescription dose. PD was then compared with diode and TLD for LINAC and tomotherapy. Mean PD for LINAC with TLD and diode was 2.52 cGy (SD 0.69), 2.07 cGy (SD 0.88) at 20 cm, respectively, while at 25 cm, it was 1.94 cGy (SD 0.58) and 1.5 cGy (SD 0.75), respectively. Mean PD for tomotherapy with TLD and diode was 1.681 cGy SD 0.53) and 1.58 (SD 0.44) at 20 cm, respectively. The PD was 1.24 cGy (SD 0.42) and 1.088 cGy (SD 0.35) at 25 cm, respectively, for tomotherapy. Overall, PD from tomotherapy was found lower than LINAC by the factor of 1.2-1.5. PD measurement is essential to find out the potential of secondary cancer. PD for both (conventional LINAC) and novel LINACs (tomotherapy) were measured and compared with each other. The comparison of the values for PD presented in this work and those published in the literature is difficult because of the different experimental conditions. The diode and TLD readings were reproducible and both the detector readings were comparable. PMID:23531765

Mysteries of LiF TLD response following high ionisation density irradiation: nanodosimetry and track structure theory, dose response and glow curve shapes.

PubMed

Horowitz, Y; Fuks, E; Datz, H; Oster, L; Livingstone, J; Rosenfeld, A

2011-06-01

Three outstanding effects of ionisation density on the thermoluminescence (TL) mechanisms giving rise to the glow peaks of LiF:Mg,Ti (TLD-100) are currently under investigation: (1) the dependence of the heavy charged particle (HCP) relative efficiency with increasing ionisation density and the effectiveness of its modelling by track structure theory (TST), (2) the behaviour of the TL efficiency, f(D), as a function of photon energy and dose. These studies are intended to promote the development of a firm theoretical basis for the evaluation of relative TL efficiencies to assist in their application in mixed radiation fields. And (3) the shape of composite peak 5 in the glow curve for various HCP types and energies and following high-dose electron irradiation, i.e. the ratio of the intensity of peak 5a to peak 5. Peak 5a is a low-temperature satellite of peak 5 arising from electron-hole capture in a spatially correlated trapping centre/luminescent centre (TC/LC) complex that has been suggested to possess a potential as a solid-state nanodosemeter due to the preferential electron/hole population of the TC/LC at high ionisation density. It is concluded that (1) the predictions of TST are very strongly dependent on the choice of photon energy used in the determination of f(D); (2) modified TST employing calculated values of f(D) at 2 keV is in agreement with 5-MeV alpha particle experimental results for composite peak 5 but underestimates the 1.5-MeV proton relative efficiencies. Both the proton and alpha particle relative TL efficiencies of the high-temperature TL (HTTL) peaks 7 and 8 are underestimated by an order of magnitude suggesting that the HTTL efficiencies are affected by other factors in addition to radial electron dose; (3) the dose-response supralinearity of peaks 7 and 8 change rapidly with photon energy: this behaviour is explained in the framework of the unified interaction model as due to a very strong dependence on photon energy of the relative

Mysteries of LiF TLD response following high ionisation density irradiation: nanodosimetry and track structure theory, dose response and glow curve shapes

PubMed Central

Horowitz, Y.; Fuks, E.; Datz, H.; Oster, L.; Livingstone, J.; Rosenfeld, A.

2011-01-01

Three outstanding effects of ionisation density on the thermoluminescence (TL) mechanisms giving rise to the glow peaks of LiF:Mg,Ti (TLD-100) are currently under investigation: (1) the dependence of the heavy charged particle (HCP) relative efficiency with increasing ionisation density and the effectiveness of its modelling by track structure theory (TST), (2) the behaviour of the TL efficiency, f(D), as a function of photon energy and dose. These studies are intended to promote the development of a firm theoretical basis for the evaluation of relative TL efficiencies to assist in their application in mixed radiation fields. And (3) the shape of composite peak 5 in the glow curve for various HCP types and energies and following high-dose electron irradiation, i.e. the ratio of the intensity of peak 5a to peak 5. Peak 5a is a low-temperature satellite of peak 5 arising from electron-hole capture in a spatially correlated trapping centre/luminescent centre (TC/LC) complex that has been suggested to possess a potential as a solid-state nanodosemeter due to the preferential electron/hole population of the TC/LC at high ionisation density. It is concluded that (1) the predictions of TST are very strongly dependent on the choice of photon energy used in the determination of f(D); (2) modified TST employing calculated values of f(D) at 2 keV is in agreement with 5-MeV alpha particle experimental results for composite peak 5 but underestimates the 1.5-MeV proton relative efficiencies. Both the proton and alpha particle relative TL efficiencies of the high-temperature TL (HTTL) peaks 7 and 8 are underestimated by an order of magnitude suggesting that the HTTL efficiencies are affected by other factors in addition to radial electron dose; (3) the dose–response supralinearity of peaks 7 and 8 change rapidly with photon energy: this behaviour is explained in the framework of the unified interaction model as due to a very strong dependence on photon energy of the relative

Reduction in radiation exposure to nursing personnel with the use of remote afterloading brachytherapy devices

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

Grigsby, P.W.; Perez, C.A.; Eichling, J.

The radiation exposure to nursing personnel from patients with brachytherapy implants on a large brachytherapy service were reviewed. Exposure to nurses, as determined by TLD monitors, indicates a 7-fold reduction in exposure after the implementation of the use of remote afterloading devices. Quarterly TLD monitor data for six quarters prior to the use of remote afterloading devices demonstrate an average projected annual dose equivalent to the nurses of 152 and 154 mrem (1.5 mSv). After the implementation of the remote afterloading devices, the quarterly TLD monitor data indicate an average dose equivalent per nurse of 23 and 19 mrem (0.2more » mSv). This is an 87% reduction in exposure to nurses with the use of these devices (p less than 0.01).« less

Chlorination and chloramination of bisphenol A, bisphenol F, and bisphenol A diglycidyl ether in drinking water.

PubMed

Lane, Rachael F; Adams, Craig D; Randtke, Stephen J; Carter, Ray E

2015-08-01

Bisphenol A (BPA), bisphenol F (BPF), and bisphenol A diglycidyl ether (BADGE) are common components of epoxy coatings used in food packaging and in drinking water distribution systems. Thus, leachates from the epoxy may be exposed to the disinfectants free chlorine (Cl2/HOCl/OCl(-)) and monochloramine (MCA, NH2Cl). Bisphenols are known endocrine disrupting chemicals (EDC) with estrogenic activity. Chlorination by-products have the potential to have reduced or enhanced estrogenic qualities, and are, therefore, of interest. In this work, chlorination reactions for bisphenols and BADGE were explored (via LC/MS/MS) and kinetic modeling (using a pseudo-first order approach) was conducted to predict the fate of these compounds in drinking water. The half-lives of BPA and BPF with 1 mg/L of free chlorine ranged from 3 to 35 min over the pH range from 6 to 11 and the temperature range of 10-25 °C. Half-lives for reactions of BPA and BPF with a nominal MCA concentration of 3.5 mg/L as Cl2 were from 1 to 10 days and were greater at higher pH and lower temperature. Formation of chlorinated bisphenol A by-products was observed during the kinetic studies. BADGE was found unreactive with either oxidant. Copyright © 2015. Published by Elsevier Ltd.

Characterization of the Radiological Environment at J-Village during Operation Tomodachi

DTIC Science & Technology

2013-02-01

individual as compared to those for the helicopter crew members (Appendix A). 3.2.2. Other Relevant Dosimetry Results Thermoluminescent dosimeter ( TLD ...internal monitoring results are available for 14 of these individuals. External dosimetry data (EPD and TLD ) showed that the maximum recorded dose for an...Washington, DC. http://www.NNSAResponseData.net. Accessed December 7. USAFCRD (U. S. Air Force Center for Radiation Dosimetry ), 2011. Electronic Pocket

Reference Dosimetry for the 1992 NATO Battlefield Dosimetry Intercomparison at the Army Pulse Radiation Facility

DTIC Science & Technology

1993-04-01

dosimeter using the Rh -103(n,n’) Rh - 103m reaction. Health Physics 25: 291-297, 1973. 11. Zeman, G. H. Rhodium-103 and indium-115 inelastic scattering... Rh foil 203 .... A120 3 TLD -- 17.0 -- TE-Mg ICI 205 16.1 221 93 APRF TE-Mg IC 205 17.6 223 92 CaF TLD -- 22.1 .... Average 204 17.5 222 92 +/- 1.5

Development and validation of RAYDOSE: a Geant4-based application for molecular radiotherapy

NASA Astrophysics Data System (ADS)

Marcatili, S.; Pettinato, C.; Daniels, S.; Lewis, G.; Edwards, P.; Fanti, S.; Spezi, E.

2013-04-01

We developed and validated a Monte-Carlo-based application (RAYDOSE) to generate patient-specific 3D dose maps on the basis of pre-treatment imaging studies. A CT DICOM image is used to model patient geometry, while repeated PET scans are employed to assess radionuclide kinetics and distribution at the voxel level. In this work, we describe the structure of this application and present the tests performed to validate it against reference data and experiments. We used the spheres of a NEMA phantom to calculate S values and total doses. The comparison with reference data from OLINDA/EXM showed an agreement within 2% for a sphere size above 2.8 cm diameter. A custom heterogeneous phantom composed of several layers of Perspex and lung equivalent material was used to compare TLD measurements of gamma radiation from 131I to Monte Carlo simulations. An agreement within 5% was found. RAYDOSE has been validated against reference data and experimental measurements and can be a useful multi-modality platform for treatment planning and research in MRT.

44th Annual Gun and Missile Systems Conference and Exhibition

DTIC Science & Technology

2009-04-09

IR S A R GOT S/ COT S/OT S Client Vie ws We b-Based Vi ews 2D V i s 3D Vi s DS P S T F D S C MT IX WT X ETS Web - Ba...08-Q-1904 on NSWCDD web site – FY10 Announcement (Pending) • EO/ IR /LST integration into a Tier 2 UAS targeting ball • Solicitation FY10, award at...present picture ID. Badges must be worn at all conference functions. Proceedings will be available on the web one to two weeks after

Hand and body radiation exposure with the use of mini C-arm fluoroscopy.

PubMed

Tuohy, Christopher J; Weikert, Douglas R; Watson, Jeffry T; Lee, Donald H

2011-04-01

To determine whole body and hand radiation exposure to the hand surgeon wearing a lead apron during routine intraoperative use of the mini C-arm fluoroscope. Four surgeons (3 hand attending surgeons and 1 hand fellow) monitored their radiation exposure for a total of 200 consecutive cases (50 cases per surgeon) requiring mini C-arm fluoroscopy. Each surgeon measured radiation exposure with a badge dosimeter placed on the outside breast pocket of the lead apron (external whole body exposure), a second badge dosimeter under the lead apron (shielded whole body exposure), and a ring dosimeter (hand exposure). Completed records were noted in 198 cases, with an average fluoroscopy time of 133.52 seconds and average cumulative dose of 19,260 rem-cm(2) per case. The total measured radiation exposures for the (1) external whole body exposure dosimeters were 16 mrem (for shallow depth), 7 mrem (for eye depth), and less than 1 mrem (for deep depth); (2) shielded whole body badge dosimeters recorded less than 1 mrem; and (3) ring dosimeters totaled 170 mrem. The total radial exposure for 4 ring dosimeters that had registered a threshold of 30 mrem or more of radiation exposure was 170 mrem at the skin level, for an average of 42.5 mrem per dosimeter ring or 6.3 mrem per case. This study of whole body and hand radiation exposure from the mini C-arm includes the largest number of surgical cases in the published literature. The measured whole body and hand radiation exposure received by the hand surgeon from the mini C-arm represents a minimal risk of radiation, based on the current National Council on Radiation Protection and Management standards of annual dose limits (5,000 mrem per year for whole body and 50,000 mrem per year to the extremities). Copyright © 2011 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

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

Nelson, Cynthia Lee

There is a need in security systems to rapidly and accurately grant access of authorized personnel to a secure facility while denying access to unauthorized personnel. In many cases this role is filled by security personnel, which can be very costly. Systems that can perform this role autonomously without sacrificing accuracy or speed of throughput are very appealing. To address the issue of autonomous facility access through the use of technology, the idea of a ''secure portal'' is introduced. A secure portal is a defined zone where state-of-the-art technology can be implemented to grant secure area access or to allowmore » special privileges for an individual. Biometric technologies are of interest because they are generally more difficult to defeat than technologies such as badge swipe and keypad entry. The biometric technologies selected for this concept were facial and gait recognition. They were chosen since they require less user cooperation than other biometrics such as fingerprint, iris, and hand geometry and because they have the most potential for flexibility in deployment. The secure portal concept could be implemented within the boundaries of an entry area to a facility. As a person is approaching a badge and/or PIN portal, face and gait information can be gathered and processed. The biometric information could be fused for verification against the information that is gathered from the badge. This paper discusses a facial recognition technology that was developed for the purposes of providing high verification probabilities with low false alarm rates, which would be required of an autonomous entry control system. In particular, a 3-D facial recognition approach using Fisher Linear Discriminant Analysis is described. Gait recognition technology, based on Hidden Markov Models has been explored, but those results are not included in this paper. Fusion approaches for combining the results of the biometrics would be the next step in realizing the secure

76 FR 62387 - Public User ID Badging

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-07

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Post Remedial Action Report, Lansdowne Radioactive Residence Complex, Dismantlement/Removal Project. Volume 1. Government Operations

DTIC Science & Technology

1990-06-01

25 5.1.1.2 Physical Examination ....................................... 26 5.1.1.3 In- Vivo lionitoring...thermoluminescent dosimeters ( TLD ) used on the Lansdowne project utilized a phosphor sensitive to ionizing radiation. The phosphor stored the energy of the...deposited in the body. in- vivo counting Measurements of internal radioactivity made at the surface (outside) of the body and based on the fact that

USAF Summer Research Program - 1993 High School Apprenticeship Program Final Reports, Volume 12, Armstrong Laboratory

DTIC Science & Technology

1993-12-01

on Panasonic TLD . Panasonic Industrial Company; Secaucus, New Jersey. 5. Thurlow, Ronald M. "Neutron Dosimetry Using a Panasonic Thermoluminescent...Radiation Dosimetry Branch Brooks Air Force Base San Antonio, Texas 78235 Final Report for: AFOSR Summer Research Program Armstrong Laboratory Sponsored...Associate Radiation Dosimetry Branch Armstrong Laboratory Abstract In an attempt to improve personnel monitoring for neutron emissions, Panasonic has

[Prostate radiation therapy: in vivo measurement of the dose delivered by kV-CBCT].

PubMed

Marinello, G; Mege, J-P; Besse, M-C; Kerneur, G; Lagrange, J-L

2009-09-01

To investigate if the regular use of kV-CBCT notably increases the dose delivered to tumor and surrounding healthy tissues. Images were obtained using a Varian equipment (OBI version 1.3, 645 to 650 projections in 370 degrees to acquire image), and patients were irradiated at source-tumor distance: 100cm. In vivo measurements were performed using radio-thermoluminescent dosimeters Harshaw-TLD700H (TLD) at skin (anterior-posterior and lateral axis crossing the rotation axis), with a fourth TLD group under the table thanks to a retrolaser. TLD's were calibrated at the kV-CBCT effective energy (64 keV), and the method validated using an anthropomorphic phantom, in which Gafchromic EBT films were also inserted. The phantom study showed that the dose distribution depends on the phantom position relative to the axis and that the doses measured at the phantom surface using TLD and films (good agreement) were maximum at the entrance of the anterior-posterior axis. Their arithmetic mean was equal, or a slightly greater than doses measured at mid-thickness of the phantom and at the level of the rectum (OAR). In vivo measurements performed on the five first patients (125 kV-CBCT) yield a mean skin dose per kV-CBCT varying from 5.8+/-0.1 to 7.3+/-0.2 cGy on the anterior-posterior axis. Lateral skin doses vary from 3.4+/-0.2 to 4.5+/-0.2 cGy. Doses delivered by repeated kV-CBCT are not negligible. They should be taken into account, but questions about the RBE to be applied to kilovoltage X-rays are raised.

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Prediction and Measurement of X-Ray Spectral and Intensity Distributions from Low Energy Electron Impact Sources

NASA Technical Reports Server (NTRS)

Edwards, David L.

1999-01-01

In-vacuum electron beam welding is a technology that NASA considered as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. The radiation exposure to astronauts performing the in-vacuum electron beam welding must be characterized and minimized to insure safe operating conditions. This investigation characterized the x-ray environment due to operation of an in-vacuum electron beam welding tool. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests consisted of Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) and exposed to x-ray radiation generated by operation of an in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 KeV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by electron impact with metal. These x-ray spectra were used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the in-vacuum electron beam welding tool. The calculated absorbed dose

SU-E-T-101: Determination and Comparison of Correction Factors Obtained for TLDs in Small Field Lung Heterogenous Phantom Using Acuros XB and EGSnrc

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

Soh, R; Lee, J; Harianto, F

Purpose: To determine and compare the correction factors obtained for TLDs in 2 × 2cm{sup 2} small field in lung heterogenous phantom using Acuros XB (AXB) and EGSnrc. Methods: This study will simulate the correction factors due to the perturbation of TLD-100 chips (Harshaw/Thermoscientific, 3 × 3 × 0.9mm{sup 3}, 2.64g/cm{sup 3}) in small field lung medium for Stereotactic Body Radiation Therapy (SBRT). A physical lung phantom was simulated by a 14cm thick composite cork phantom (0.27g/cm{sup 3}, HU:-743 ± 11) sandwiched between 4cm thick Plastic Water (CIRS,Norfolk). Composite cork has been shown to be a good lung substitute materialmore » for dosimetric studies. 6MV photon beam from Varian Clinac iX (Varian Medical Systems, Palo Alto, CA) with field size 2 × 2cm{sup 2} was simulated. Depth dose profiles were obtained from the Eclipse treatment planning system Acuros XB (AXB) and independently from DOSxyznrc, EGSnrc. Correction factors was calculated by the ratio of unperturbed to perturbed dose. Since AXB has limitations in simulating actual material compositions, EGSnrc will also simulate the AXB-based material composition for comparison to the actual lung phantom. Results: TLD-100, with its finite size and relatively high density, causes significant perturbation in 2 × 2cm{sup 2} small field in a low lung density phantom. Correction factors calculated by both EGSnrc and AXB was found to be as low as 0.9. It is expected that the correction factor obtained by EGSnrc wlll be more accurate as it is able to simulate the actual phantom material compositions. AXB have a limited material library, therefore it only approximates the composition of TLD, Composite cork and Plastic water, contributing to uncertainties in TLD correction factors. Conclusion: It is expected that the correction factors obtained by EGSnrc will be more accurate. Studies will be done to investigate the correction factors for higher energies where perturbation may be more pronounced.« less

A system for electron therapy dosimetry surveys with thermoluminescence dosimeters.

PubMed

Soares, C G; Ehrlich, M; Padikal, T N; Gromadzki, Z C

1982-11-01

Radiation-therapy dosimetry surveys employing thermoluminescence dosimeters (TLDs) are now being considered for high-energy electron beams. Using a system of individually calibrated pressed LiF TLDs in a water and a polystyrene phantom, we established that the distortions of depth-dose distributions in non-conducting materials previously observed at high absorbed doses and high dose rates were not detectable in the present geometry at doses and dose rates as much as 40 times higher than those employed in radiation therapy. The system was then used to measure TLD response in water and in polystyrene in the nominal electron-energy range from 7 to 18 MeV. In the water phantom, the well-known trend for TLD response to decrease with increasing electron energy was observed. In the polystyrene phantom, TLD response was found to be independent of electron energy.

What Is a Mammogram and When Should I Get One?

MedlinePlus

... Statistics What CDC Is Doing Research African American Women and Mass Media Campaign Public Service Announcements Print Materials Buttons and Badges Stay Informed Cancer Home What Is a Mammogram? Language: English (US) Español ( ...

A Symposium on Pre-1900 Classics Worth Using in School.

ERIC Educational Resources Information Center

English Journal, 1983

1983-01-01

Various contributors recommend "The Odyssey,""Julius Caesar,""A Dog's Tale,""Ivanhoe,""Star Wars,""The Red Badge of Courage,""Demian,""Antigone,""Children of Crisis," and "Frankenstein" for use in literature classes and justify their recommendations. (JL)

DRDC Ottawa Participation in the SILENE Accident Dosimetry Intercomparison Exercise. June 10-21, 2002

DTIC Science & Technology

2002-11-01

of CaF2:Mn and A120 3 TLDs for gamma-ray dosimetry ). In addition, DRDC Ottawa has recently substantially expanded its efforts in radiation dosimetry ...use of any real- time electronic dosimeter. Foils have long been proposed and used for criticality dosimetry (as well as for general monitoring of...ray Dosimetry DRDC Ottawa offers a number (over five) of various thermoluminescence dosimetry ( TLD ) systems. The choice of any particular TLD depends

AFRRI Reports, April-June 1990

DTIC Science & Technology

1990-07-01

described in detail in the companion paper (4). In vivo dosimetry was done using Harshaw (Solon, Ohio) TLD -100 lith- ium fluoride thermoluminescent...provide replicate measurements. Two separate dosimetry tubes were developed (Fig. 1). The first contained 30 TLD cap- sules loaded in a 90-cm length...situ Dosimetry Tube 55 3 LIF TLDs In gelatin capsule TUBEB LIF TLDs Nylon Balls Steel Ball Epoxy Plug I Scale 3 cm - J FIG. I

75 FR 57768 - Access to Confidential Business Information by Eastern Research Group and Its Identified...

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Added aluminum shielding to attenuate back scatter electrons from intra-oral lead shields.

PubMed

Weidlich, G A; Nuesch, C E; Fuery, J J

1996-01-01

An intra-oral lead shield was developed that consists of a lead base with an aluminum layer that is placed upstream of the lead base. Several such shields with various thicknesses of Al layers were manufactured and quantitatively evaluated in 6 MeV and 12 MeV electron radiation by Thermoluminescent dosimetry (TLD) measurements. The clinical relevance was established by using a 5 cm backscatter block down-stream of the lead shield to simulate anatomical structures of the head and a 0.5 cm superflab bolus upstream of the Al layers of the shield to simulate the patient's lip or cheek. The TLDs were placed between the Al layers of the shield and the superflab to determine the intra-oral skin dose. TLD exposure results revealed that 59.8% of the skin dose at 6 MeV and 45.1% of the skin dose at 12 MeV is due to backscattered electrons. Introduction of a 3.0 mm thick Al layer reduces the backscatter contribution to 13.5% of the back scatter dose at 6 MeV and 56.3% of the back scatter dose at 12 MeV electron radiation.

Voss with Pille TLD reader

NASA Image and Video Library

2001-06-26

ISS002-E-7814 (26 June 2001) --- James S. Voss, Expedition Two flight engineer, sets up the Human Research Facility's (HRF) Dosimetric Mapping (DOSMAP) Power Distribution Unit (PDU) in Destiny. The image was taken with a digital still camera.

BaSO4:Eu as an energy independent thermoluminescent radiation dosimeter for gamma rays and C6+ ion beam

NASA Astrophysics Data System (ADS)

Sharma, Kanika; Bahl, Shaila; Singh, Birendra; Kumar, Pratik; Lochab, S. P.; Pandey, Anant

2018-04-01

BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impurity element and compared to the commercially available thermoluminescent dosimeter (TLD) LiF:Mg,Ti (TLD-100) and by extension also to CaSO4:Dy (TLD-900) so as to achieve its maximum thermoluminescence (TL) sensitivity. Further, the energy dependence property of this barite nanophosphor is also explored at length by exposing the phosphor with 1.25 MeV of Co-60, 0.662 MeV of Cs-137, 85 MeV and 65 MeV of Carbon ion beams. Various batches of the phosphor at hand (with impurity concentrations being 0.05, 0.10, 0.20, 0.50 and 1.00 mol%) are prepared by the chemical co-precipitation method out of which BaSO4:Eu with 0.20 mol% Eu exhibits the maximum TL sensitivity. Further, the optimized nanophosphor exhibits a whopping 28.52 times higher TL sensitivity than the commercially available TLD-100 and 1.426 times higher sensitivity than TLD-900, a noteworthy linear response curve for an exceptionally wide range of doses i.e. 10 Gy to 2 kGy and a simple glow curve structure. Furthermore, when the newly optimized nanophosphor is exposed with two different energies of gamma radiations, namely 1.25 MeV of Co-60 (dose range- 10-300 Gy) and 0.662 MeV of Cs-137 (dose range- 1-300 Gy), it is observed that the shape and structure of the glow curves remain remarkably similar for different energies of radiation while the TL response curve shows little to no variation. When exposed to different energies of carbon ion beam BaSO4:Eu displays energy independence at lower doses i.e. from 6.059 to 14.497 kGy. Finally, even though energy independence is lost at higher doses, the material shows high sensitivity to higher energy (85 MeV) of carbon beam compared to the lower energy (65 MeV of C6+) and saturation is apparent only after 121.199 kGy. Therefore the present nanophosphor displays potential as an energy independent TLD.

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From IDs to Ice Cream to "I, Claudius": Security Is in the Cards at Cleveland Hill Union Free School District.

ERIC Educational Resources Information Center

Passmore, Cheryl

2002-01-01

Describes the use of plastic identity badges with photographs and barcodes issued to all administrators, teachers, staff members, and students in grades 6-12 at the Cleveland Hill Union Free School District in Cheektowaga, New York. (PKP)

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Neutron Fading Characteristics of Copper Doped Lithium Fluoride (LiF: MCP) Thermoluminescent Dosimeters (TLDs)

DTIC Science & Technology

2008-05-21

Albedo Dosimetry TLDs that are used for neutron or neutron-photon personnel dosimetry are albedo dosimeters. The word albedo simply means the proportion... dosimetry . When LiF: MCP is exposed to thermal neutron irradiation, there is no obvious change in the glow curve shape. In the case of TLD -100, the...LiF: MCP undergoes compared to TLD -100. Therefore, LET results in significant variations in TL output for LiF: MCP. Limitations of Albedo Dosimetry

Anthropomorphic Phantom Radiation Dosimetry at the NATO Standard Reference Point at Aberdeen Proving Ground,

DTIC Science & Technology

1987-04-01

and would still be well under 10(C. .% % p., I V a- E p - -12 - IABLE 8 (a) TLD results for phantom dosimetry - all values shown are measured charge...SAI. Conclusions The current DREO dosimetry system-consisting of bubble, CR39 and TLD dosimeters - has proven capable of producing meaningful results at...MC FILE CoPy’ Defence nationale 00 ANTHROPOMORPHIC PHANTOM RADIATION DOSIMETRY AT THE NATO STANDARD OREFERENCE POINT AT ABERDEEN PROVING GROUND by T

An Investigation of Nonuniform Dose Deposition From an Electron Beam

DTIC Science & Technology

1994-08-01

to electron - beam pulse. Ceramic package HIPEC Lid Electron beam Die Bond wires TLD TLD Silver epoxy 6 package cavity die TLD’s 21 3 4 5 Figure 2...these apertures was documented in a previous experiment relating to HIFX electron -beam dosimetry .2 The hardware required for this setup was a 60-cm...impurity serves 2Gregory K. Ovrebo, Steven M. Blomquist, and Steven R. Murrill, A HIFX Electron -Beam Dosimetry System, Army Research Laboratory, ARL-TR

Thermoluminescence glow-curve characteristics of LiF phosphors at high doses of gamma radiation

NASA Astrophysics Data System (ADS)

Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

2013-05-01

High doses of ionising radiation are becoming increasingly common for radiation-processing applications of various medical, agricultural and polymer products using gamma and electron beams. The objective of this work was to study thermoluminescence (TL) glow-curve characteristics of commonly used commercial LiF TL phosphors at high doses of radiation with a view to use them in dosimetry of radiation-processing applications. The TL properties of TLD 100 and 700 phosphors, procured from the Thermo-Scientific (previously Harshaw) company, have been studied in the dose range of 1-60 kGy. The shift in glow peaks was observed in this dose range. Integral TL responses of TLD 100 and TLD 700 were found to decrease as a linear function of dose in the range of 5-50 kGy. The paper describes initial results related to the glow-curve characteristics of these phosphors.

Thermoluminescence response of flat optical fiber subjected to 9 MeV electron irradiations

NASA Astrophysics Data System (ADS)

Hashim, S.; Omar, S. S. Che; Ibrahim, S. A.; Hassan, W. M. S. Wan; Ung, N. M.; Mahdiraji, G. A.; Bradley, D. A.; Alzimami, K.

2015-01-01

We describe the efforts of finding a new thermoluminescent (TL) media using pure silica flat optical fiber (FF). The present study investigates the dose response, sensitivity, minimum detectable dose and glow curve of FF subjected to 9 MeV electron irradiations with various dose ranges from 0 Gy to 2.5 Gy. The above-mentioned TL properties of the FF are compared with commercially available TLD-100 rods. The TL measurements of the TL media exhibit a linear dose response over the delivered dose using a linear accelerator. We found that the sensitivity of TLD-100 is markedly 6 times greater than that of FF optical fiber. The minimum detectable dose was found to be 0.09 mGy for TLD-100 and 8.22 mGy for FF. Our work may contribute towards the development of a new dosimeter for personal monitoring purposes.

Comparison of the dose distribution obtained from dosimetric systems with intensity modulated radiotherapy planning system in the treatment of prostate cancer

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

Gökçe, M., E-mail: mgokce@adu.edu.tr; Uslu, D. Koçyiğit; Ertunç, C.

The aim of this study is to compare Intensity Modulated Radiation Therapy (IMRT) plan of prostate cancer patients with different dose verification systems in dosimetric aspects and to compare these systems with each other in terms of reliability, applicability and application time. Dosimetric control processes of IMRT plan of three prostate cancer patients were carried out using thermoluminescent dosimeter (TLD), ion chamber (IC) and 2D Array detector systems. The difference between the dose values obtained from the dosimetric systems and treatment planning system (TPS) were found to be about % 5. For the measured (TLD) and calculated (TPS) doses %3more » percentage differences were obtained for the points close to center while percentage differences increased at the field edges. It was found that TLD and IC measurements will increase the precision and reliability of the results of 2D Array.« less

Evaluation of clinical use of OneDose™ metal oxide semiconductor field-effect transistor detectors compared to thermoluminescent dosimeters to measure skin dose for adult patients with acute lymphoblastic leukemia

PubMed Central

Al-Mohammed, Huda Ibrahim

2011-01-01

Background: Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to their bone marrow transplant. It involves the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore, it is important to measure and monitor the skin dose during the treatment. Thermoluminescent dosimeters (TLDs) and the OneDose™ metal oxide semiconductor field effect transistor (MOSFET) detectors are used during treatment delivery to measure the radiation dose and compare it with the target prescribed dose. Aims: The primary goal of this study was to measure the variation of skin dose using OneDose MOSFET detectors and TLD detectors, and compare the results with the target prescribed dose. The secondary aim was to evaluate the simplicity of use and determine if one system was superior to the other in clinical use. Material and Methods: The measurements involved twelve adult patients diagnosed with acute lymphoblastic leukemia. TLD and OneDose MOSFET dosimetry were performed at ten different anatomical sites of each patient. Results: The results showed that there was a variation between skin dose measured with OneDose MOSFET detectors and TLD in all patients. However, the variation was not significant. Furthermore, the results showed for every anatomical site there was no significant different between the prescribed dose and the dose measured by either TLD or OneDose MOSFET detectors. Conclusion: There were no significant differences between the OneDose MOSFET and TLDs in comparison to the target prescribed dose. However, OneDose MOSFET detectors give a direct read-out immediately after the treatment, and their simplicity of use to compare with TLD detectors may make them preferred for clinical use. PMID:22171243

Dosimetry audit of radiotherapy treatment planning systems.

PubMed

Bulski, Wojciech; Chełmiński, Krzysztof; Rostkowska, Joanna

2015-07-01

In radiotherapy Treatment Planning Systems (TPS) various calculation algorithms are used. The accuracy of dose calculations has to be verified. Numerous phantom types, detectors and measurement methodologies are proposed to verify the TPS calculations with dosimetric measurements. A heterogeneous slab phantom has been designed within a Coordinated Research Project (CRP) of the IAEA. The heterogeneous phantom was developed in the frame of the IAEA CRP. The phantom consists of frame slabs made with polystyrene and exchangeable inhomogeneity slabs equivalent to bone or lung tissue. Special inserts allow to position thermoluminescent dosimeters (TLD) capsules within the polystyrene slabs below the bone or lung equivalent slabs and also within the lung equivalent material. Additionally, there are inserts that allow to position films or ionisation chamber in the phantom. Ten Polish radiotherapy centres (of 30 in total) were audited during on-site visits. Six different TPSs and five calculation algorithms were examined in the presence of inhomogeneities. Generally, most of the results from TLD were within 5 % tolerance. Differences between doses calculated by TPSs and measured with TLD did not exceed 4 % for bone and polystyrene equivalent materials. Under the lung equivalent material, on the beam axis the differences were lower than 5 %, whereas inside the lung equivalent material, off the beam axis, in some cases they were of around 7 %. The TLD results were confirmed with the ionisation chamber measurements. The comparison results of the calculations and the measurements allow to detect limitations of TPS calculation algorithms. The audits performed with the use of heterogeneous phantom and TLD seem to be an effective tool for detecting the limitations in the TPS performance or beam configuration errors at audited radiotherapy departments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Improvement and Analysis of the Radiation Response of RADFET Dosimeters

DTIC Science & Technology

1992-06-15

TLD ), silicon p-i-n diode responses and silicon calorimetry (AWE Dosimetry Service). Intensive preparations were made by REM and the experiments were...SUB-GROUP dose: RADFET : tactical dosimetry silicon : metal-oxide- 0705 emiconductor (MOS) field effect transistor (FET) : silicon Idioxide space...1.1 Principle of a dosimetry system, based on the RADFET (radiation-sensitive field-effect transistor) (a) microscopic cross-section of chip (b) chip

77 FR 4550 - Promising and Practical Strategies to Increase Postsecondary Success

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-30

... Education. Appendix A: Standard Keywords and Tags Accelerated Learning Achievement Gap Closure Adult Education Affordability Assessment Technology Badges Basic Skills Blended Learning Block Scheduling [[Page... Collection/Use Degree Attainment Developmental/Remedial Education Digital Materials Dual Degrees Earn and...

Native Fluorescence Detection Methods, Devices, and Systems for Organic Compounds

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Lane, Arthur L. (Inventor); Reid, Ray D. (Inventor)

2018-01-01

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds VOCs have been identified as serious health hazards. Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined.

Native Fluorescence Detection Methods, Devices, and Systems for Organic Compounds

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor); Bhartia, Rohit (Inventor)

2016-01-01

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds VOCs have been identified as serious health hazards. Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined.

Cosmic dosimetry using TLD aboard spacecrafts of the "Cosmos" series

NASA Astrophysics Data System (ADS)

Hübner, K.; Schmidt, P.; Fellinger, J.

Thermoluminescent (TL) detectors were used for dosimetric investigations on the outer surface as well as inside Soviet spacecrafts of the "Cosmos" series. At the outer surface, ultrathin TL detectors, based on CaF 2-PTFE and LiF, were arranged in special stacks and exposed to unshielded cosmic radiation. The strong decrease of dose within a few mg/cm 2 demonstrates that weakly penetrating radiation is dominating in the radiation field under investigation. On the basis of glow curve analysis of LiF thermoluminescent detectors it could be shown, that the high doses are caused by electrons.

Cosmic dosimetry using TLD aboard spacecrafts of the "Cosmos" series.

PubMed

Hubner, K; Schmidt, P; Fellinger, J

1994-11-01

Thermoluminescent (TL) detectors were used for dosimetric investigations on the outer surface as well as inside Soviet spacecrafts of the "Cosmos" series. At the outer surface, ultrathin TL detectors, based on CaF2-PTFE and LiF, were arranged in special stacks and exposed to unshielded cosmic radiation. The strong decrease of dose within a few mg/cm2 demonstrates that weakly penetrating radiation is dominating in the radiation field under investigation. On the basis of glow curve analysis of LiF thermoluminescent detectors it could be shown, that the high doses are caused by electrons.

Evaluation and comparison of absorbed dose for electron beams by LiF and diamond dosimeters

NASA Astrophysics Data System (ADS)

Mosia, G. J.; Chamberlain, A. C.

2007-09-01

The absorbed dose response of LiF and diamond thermoluminescent dosimeters (TLDs), calibrated in 60Co γ-rays, has been determined using the MCNP4B Monte Carlo code system in mono-energetic megavoltage electron beams from 5 to 20 MeV. Evaluation of the dose responses was done against the dose responses of published works by other investigators. Dose responses of both dosimeters were compared to establish if any relation exists between them. The dosimeters were irradiated in a water phantom with the centre of their top surfaces (0.32×0.32 cm 2), placed at dmax perpendicular to the radiation beam on the central axis. For LiF TLD, dose responses ranged from 0.945±0.017 to 0.997±0.011. For the diamond TLD, the dose response ranged from 0.940±0.017 to 1.018±0.011. To correct for dose responses by both dosimeters, energy correction factors were generated from dose response results of both TLDs. For LiF TLD, these correction factors ranged from 1.003 up to 1.058 and for diamond TLD the factors ranged from 0.982 up to 1.064. The results show that diamond TLDs can be used in the place of the well-established LiF TLDs and that Monte Carlo code systems can be used in dose determinations for radiotherapy treatment planning.

Thermoluminescence dosimetry and its applications in medicine--Part 2: History and applications.

PubMed

Kron, T

1995-03-01

Thermoluminescence dosimetry (TLD) has been available for dosimetry of ionising radiation for nearly 100 years. The variety of materials and their different physical forms allow the determination of different radiation qualities over a wide range of absorbed dose. This makes TL dosimeters useful in radiation protection where dose levels of microGy are monitored as well as in radiotherapy where doses up to several Gray are to be measured. The major advantages of TL detectors are their small physical size and that no cables or auxiliary equipment is required during the dose assessment. Therefore TLD is a good method for point dose measurements in phantoms as well as for in vivo dosimetry on patients during radiotherapy treatment. As an integrative dosimetric technique, it can be applied to personal dosimetry and it lends itself to the determination of dose distributions due to multiple or moving radiation sources (e.g. conformal and dynamic radiotherapy, computed tomography). In addition, TL dosimeters are easy to transport, and they can be mailed. This makes them well suited for intercomparison of doses delivered in different institutions. The present article aims at describing the various applications TLD has found in medicine by taking into consideration the physics and practice of TLD measurements which have been discussed in the first part of this review (Australas. Phys. Eng. Sci. Med. 17: 175-199, 1994).

Y-12 Plant decontamination and decommissioning technology logic diagram for Building 9201-4. Volume 2: Technology logic diagram

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

NONE

1994-09-01

The Y-12 Plant Decontamination and Decommissioning Technology Logic Diagram for Building 9201-4 (TLD) was developed to provide a decision-support tool that relates decontamination and decommissioning (D and D) problems at Bldg. 9201-4 to potential technologies that can remediate these problems. This TLD identifies the research, development, demonstration, testing, and evaluation needed for sufficient development of these technologies to allow for technology transfer and application to D and D and waste management (WM) activities. It is essential that follow-on engineering studies be conducted to build on the output of this project. These studies will begin by selecting the most promising technologiesmore » identified in the TLD and by finding an optimum mix of technologies that will provide a socially acceptable balance between cost and risk. The TLD consists of three fundamentally separate volumes: Vol. 1 (Technology Evaluation), Vol. 2 (Technology Logic Diagram), and Vol. 3 (Technology Evaluation Data Sheets). Volume 2 contains the logic linkages among environmental management goals, environmental problems, and the various technologies that have the potential to solve these problems. Volume 2 has been divided into five sections: Characterization, Decontamination, Dismantlement, Robotics/Automation, and Waste Management. Each section contains logical breakdowns of the Y-12 D and D problems by subject area and identifies technologies that can be reasonably applied to each D and D challenge.« less

76 FR 17362 - Advisory Committee on the Medical Uses of Isotopes: Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-29

... badges and complete self evaluations. Date and Time for Open Sessions: April 11, 2011, from 9 a.m. to 5 p... Commission, Two White Flint North Building, Room T2-B3, 11545 Rockville Pike, Rockville, Maryland 20852. FOR...

78 FR 70543 - Privacy Act of 1974; System of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-26

...) evaluations/job performance, deployment status, sensitive items (e.g., access and accountable badges), awards... room is inside a Sensitive Compartmented Information Facility (SCIF). Retention and disposal: Disposition pending (until the National Archives and Records Administration approves retention and disposal...

NCIS Home

Science.gov Websites

GLANCE NCIS Badge WHO WE ARE NCIS is a civilian law enforcement agency with a mission focus to with the DON and with other law enforcement organizations locally and globally. NCIS agent working at a

Resources for Teachers Starting a Planet Protector’s Club

EPA Pesticide Factsheets

EPA’s Planet Protector activities are a great way to get student’s interested in reducing, reusing and recycling. Use the activities to launch an ongoing club with our club factsheet, membership badge, activity calendar, and certificate of completion.

Teacher`s guide: Profile of terror from the New Explorers

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

NONE

This Teacher`s Guide is designed for use with fourth, fifth or sixth graders and is constructed to accompany the Bill Kurtis episode called, {open_quotes}Profile in Terror.{close_quotes} The main goal of these activities is to teach children about police department activities and jobs. Accordingly, the children are given lessons in logic, observing and inquiry, physical and psychological characteristics, before they see the video. Accompanying the video is a chronology and some questions to answer about the video. After the video, a police officer visits the classroom and demonstrates his equipment. The officer takes the badges that each student has filled outmore » back to the station for lamination. Further description on police careers are contained in lessons on evidence technicians and police detectives. The class field trip is a visit to the police station which includes getting the newly laminated badges and seeing many parts of the station. The culminating activity is a play which is read aloud in the classroom. The students write a conclusion based on information that has been provided. The activities have been created in an attempt to let students understand themselves and the life of a police officer. Because of the age of our target classes, the lessons do not go into depth on the criminal psyche.« less

78 FR 19745 - Privacy Act of 1974; Privacy Act System of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-02

... address, badge number, monthly commuting cost, email address, years of government service, grade, personal..., rideshare, or other transit program applications, status or participation reports of individuals... Subsidy Program Lead, Logistics Management Division, Location 4, as set forth in Appendix A. NOTIFICATION...

48 CFR 2052.204-70 - Security.

Code of Federal Regulations, 2010 CFR

2010-10-01

... National Security information, restricted data, formerly restricted data, and other classified data... badges. (b) It is the contractor's duty to safeguard National Security Information, Restricted Data, and Formerly Restricted Data. The contractor shall, in accordance with the Commission's security regulations...

Heart Truth

MedlinePlus

... health! Get a free badge or banner to post to your website or blog. Are you at risk for heart disease? Here's how to find out . Planning to use The Heart Truth logo? Check out our logo guidelines and downloads. ...

78 FR 61868 - Agency Information Collection Activities; Proposed Collection; Comments Requested; Extension of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-04

...: Bureau of Justice Assistance Application Form; Law Enforcement Congressional Badge of Bravery ACTION: 30... Programs' Bureau of Justice Assistance has been authorized to administer the Law Enforcement Congressional... DEPARTMENT OF JUSTICE Office of Justice Programs [OMB Number 1121-0330] Agency Information...

75 FR 19659 - Bureau of Justice Assistance; Agency Information Collection Activities: Proposed Collection...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-15

... Notice of Information Collection Under Review: New Collection Bureau of Justice Assistance Application Form: Federal Law Enforcement Officers Congressional Badge of Bravery. The Department of Justice... DEPARTMENT OF JUSTICE Office of Justice Programs [OMB Number 1121-NEW] Bureau of Justice...

75 FR 33636 - Bureau of Justice Assistance; Agency Information Collection Activities: Proposed Collection...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-14

... Notice of Information Collection Under Review: New Collection Bureau of Justice Assistance Application Form: Federal Law Enforcement Officers Congressional Badge of Bravery. The Department of Justice (DOJ... DEPARTMENT OF JUSTICE Office of Justice Programs [OMB Number 1121-NEW] Bureau of Justice...

First Impressions: Introducing Monet to Megadeth.

ERIC Educational Resources Information Center

Phillips, Leay

1989-01-01

Describes using the art and music of Impressionism to approach Stephen Crane's "The Red Badge of Courage," enabling students to understand how Crane's series of vivid episodes and brilliant but detached images melt into one another, forming a whole picture. (SR)

National Wind Technology Center | NREL

Science.gov Websites

driver's license, passport, or military ID) to obtain a security badge before entering the site. Foreign nationals must check with their host prior to their visit to make sure that a Foreign National Data Card has

Report: EPA Could Improve Physical Access and Service Continuity/Contingency Controls for Financial and Mixed-Financial Systems Located at its Research Triangle Park Campus

EPA Pesticide Factsheets

Report #2006-P-00005, December 14, 2005. Controls needed to be improved in areas such as visitor access to facilities, use of contractor access badges, and general physical access to the NCC, computer rooms outside the NCC, and media storage rooms.

STS 132 Return Samples: Assessment of Air Quality Aboard the Shuttle (STS-132) and International Space Station (ULF4)

NASA Technical Reports Server (NTRS)

James. John T.

2010-01-01

The toxicological assessments of 2 grab sample canisters (GSCs) from the Shuttle are reported. Analytical methods have not changed from earlier reports. The recoveries of the 3 surrogates (13C-acetone, fluorobenzene, and chlorobenzene) from the 2 Shuttle GSCs averaged 93, 85%, and 88%, respectively. Based on the end-of-mission sample, the Shuttle atmosphere was acceptable for human respiration. The toxicological assessment of 7 GSCs from the ISS is also shown. The recoveries of the 3 standards (as listed above) from the GSCs averaged 78, 96 and 90%, respectively. Recovery from formaldehyde control badges ranged from 90 to 112%.

Observations on personnel dosimetry for radiotherapy personnel operating high-energy LINACs.

PubMed

Glasgow, G P; Eichling, J; Yoder, R C

1986-06-01

A series of measurements were conducted to determine the cause of a sudden increase in personnel radiation exposures. One objective of the measurements was to determine if the increases were related to changing from film dosimeters exchanged monthly to TLD-100 dosimeters exchanged quarterly. While small increases were observed in the dose equivalents of most employees, the dose equivalents of personnel operating medical electron linear accelerators with energies greater than 20 MV doubled coincidentally with the change in the personnel dosimeter program. The measurements indicated a small thermal neutron radiation component around the accelerators operated by these personnel. This component caused the doses measured with the TLD-100 dosimeters to be overstated. Therefore, the increase in these personnel dose equivalents was not due to changes in work habits or radiation environments. Either film or TLD-700 dosimeters would be suitable for personnel monitoring around high-energy linear accelerators. The final choice would depend on economics and personal preference.

Evaluation of film and thermoluminescent dosimetry of high-energy electron beams in heterogeneous phantoms.

PubMed

el-Khatib, E; Antolak, J; Scrimger, J

1992-01-01

Film and thermoluminescent dosimetry (TLD) are investigated in heterogeneous phantoms irradiated by high-energy electron beams. Both film and TLD are practical dosimeters for multiple and moving beam radiotherapy. The accuracy and precision of these dosimeters for radiation dose measurements in homogeneous water-equivalent phantoms has been discussed in the literature. However, film and TLD are often used for dose measurements in heterogeneous phantoms. In those situations perturbations are produced which are related to the density and atomic number of the phantom material and the physical size and orientation of the dosimeter. In our experiments the relative dose measurements in homogeneous phantoms were the same regardless of dosimeter or dosimeter orientation. However, significant differences were observed between the dose measurements within the inhomogeneity. These differences were influenced by the type and orientation of the dosimeter in addition to the properties of the heterogeneity. These differences could be reproduced with Monte Carlo calculations and modeling of the experimental conditions.

Surface Modifier-Free Organic-Inorganic Hybridization To Produce Optically Transparent and Highly Refractive Bulk Materials Composed of Epoxy Resins and ZrO2 Nanoparticles.

PubMed

Enomoto, Kazushi; Kikuchi, Moriya; Narumi, Atsushi; Kawaguchi, Seigou

2018-04-25

Surface modifier-free hybridization of ZrO 2 nanoparticles (NPs) with epoxy-based polymers is demonstrated for the first time to afford highly transparent and refractive bulk materials. This is achieved by a unique and versatile hybridization via the one-pot direct phase transfer of ZrO 2 NPs from water to epoxy monomers without any aggregation followed by curing with anhydride. Three types of representative epoxy monomers, bisphenol A diglycidyl ether (BADGE), 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate (CEL), and 1,3,5-tris(3-(oxiran-2-yl)propyl)-1,3,5-triazinane-2,4,6-trione (TEPIC), are used to produce transparent viscous dispersions. The resulting ZrO 2 NPs are thoroughly characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and solid-state 13 C CP/MAS NMR measurements. The results from DLS and TEM analyses indicate nanodispersion of ZrO 2 into epoxy monomers as a continuous medium. A surface modification mechanism and the binding fashion during phase transfer are proposed based on the FT-IR and solid-state 13 C CP/MAS NMR measurements. Epoxy-based hybrid materials with high transparency and refractive index are successfully fabricated by heat curing or polymerizing a mixture of monomers containing epoxy-functionalized ZrO 2 NPs and methylhexahydrophthalic anhydride in the presence of a phosphoric catalyst. The TEM and small-angle X-ray scattering measurements of the hybrids show a nanodispersion of ZrO 2 in the epoxy networks. The refractive index at 594 nm ( n 594 ) increases up to 1.765 for BADGE-based hybrids, 1.667 for CEL-based hybrids, and 1.693 for TEPIC-based hybrids. Their refractive indices and Abbe's numbers are quantitatively described by the Lorentz-Lorenz effective medium expansion theory. Their transmissivity is also reasonably explained using Fresnel refraction, Rayleigh scattering, and the Lambert-Beer theories. This surface modifier-free hybridization

The Belgian End of Mission Transition Period: Lessons Learned from Third Location Decompression after Operational Deployment

DTIC Science & Technology

2011-04-01

Third Location Decompression after Operational Deployment 11 - 2 RTO-MP-HFM-205 programs is based upon the literature on combat motivation ...exposure to normal leisure activities and tourism . Massage is another interesting element in the French program. Each soldier receives at least one... gastronomy ; during the French TLD, soldiers were allowed to drink wine or beer with their meal starting at 7pm and bars closed at 1am ultimately. Alcohol

High resolution MR based polymer dosimetry versus film densitometry: a systematic study based on the modulation transfer function approach.

PubMed

Berg, A; Pernkopf, M; Waldhäusl, C; Schmidt, W; Moser, E

2004-09-07

Precise methods of modem radiation therapy such as intensity modulated radiotherapy (IMRT), brachytherapy (BT) and high LET irradiation allow for high dose localization in volumes of a few mm3. However, most dosimetry methods-ionization chambers, TLD arrangements or silicon detectors, for example-are not capable of detecting sub-mm dose variations or do not allow for simple dose imaging. Magnetic resonance based polymer dosimetry (MRPD) appears to be well suited to three-dimensional high resolution relative dosimetry but the spatial resolution based on a systematic modulation transfer function (MTF) approach has not yet been investigated. We offer a theoretical construct for addressing the spatial resolution in different dose imaging systems, i.e. the dose modulation transfer function (DMTF) approach, an experimental realization of this concept with a phantom and quantitative comparisons between two dosimetric systems: polymer gel and film dosimetry. Polymer gel samples were irradiated by Co-60 photons through an absorber grid which is characterized by periodic structures of different spatial period (a), the smallest one at width of a/2 = 280 microm. The modulation in dose under the grid is visualized via calibrated, high resolution, parameter-selective (T2) and dose images based on multi-echo MR imaging. The DMTF is obtained from the modulation depth of the spin-spin relaxation time (T2) after calibration. Voxel sizes below 0.04 mm3 could be achieved, which are significantly smaller than those reported in MR based dose imaging on polymer gels elsewhere, using a powerful gradient system and a highly sensitive small birdcage resonator on a whole-body 3T MR scanner. Dose modulations at 22% of maximum dose amplitude could be observed at about 2 line pairs per mm. The polymer DMTF results are compared to those of a typical clinical film-scanner system. This study demonstrates that MR based gel dosimetry at 200 microm pixel resolution might even be superior, with

Thermoluminescent dosimetry for LDEF experiment M0006

NASA Technical Reports Server (NTRS)

Chang, J. Y.; Giangano, D.; Kantorcik, T.; Stauber, M.; Snead, L.

1992-01-01

Experiment M0006 on the Long Duration Exposure Facility had as its objective the investigation of space radiation effects on various electronic and optical components, as well as on seed germination. The Grumman Corporate Research Center provided the radiation dosimetric measurements for M0006, comprising the preparation of thermoluminescent dosimeters (TLD) and the subsequent measurement and analysis of flight exposed and control samples. In addition, various laboratory exposures of TLD's with gamma rays and protons were performed to obtain a better understanding of the flight exposures.

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.

Evaluation of the response to xenon-133 radiations by thermoluminescent dosimeters used during the accident at Three Mile Island.

PubMed

Riley, R J; Zanzonico, P B; Masterson, M E; St Germain, J M; Laughlin, J S

1982-03-01

An evaluation is presented of the accuracy and sensitivity of three types of TLD's used during the accident at the Three Mile Island Nuclear Station. This evaluation indicated that, due to the method of calibration, all the dosimeters over-responded to 133Xe radiations. The response ranged from slightly above unity to almost two. Exposures of the TLD's were of two types, namely, the characteristic X-rays either were or were not filtered from the beam. The angular sensitivity of the dosimeters is also reported.