WorldWideScience

Sample records for online dose measurements

  1. Online Radiation Dose Measurement System for ATLAS experiment

    CERN Document Server

    Mandić, I; The ATLAS collaboration

    2012-01-01

    Particle detectors and readout electronics in the high energy physics experiment ATLAS at the Large Hadron Collider at CERN operate in radiation field containing photons, charged particles and neutrons. The particles in the radiation field originate from proton-proton interactions as well as from interactions of these particles with material in the experimental apparatus. In the innermost parts of ATLAS detector components will be exposed to ionizing doses exceeding 100 kGy. Energetic hadrons will also cause displacement damage in silicon equivalent to fluences of several times 10e14 1 MeV-neutrons per cm2. Such radiation doses can have severe influence on the performance of detectors. It is therefore very important to continuously monitor the accumulated doses to understand the detector performance and to correctly predict the lifetime of radiation sensitive components. Measurements of doses are important also to verify the simulations and represent a crucial input into the models used for predicting future ...

  2. SU-E-T-602: Patient-Specific Online Dose Verification Based On Transmission Detector Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Thoelking, J; Yuvaraj, S; Jens, F; Lohr, F; Wenz, F; Wertz, H; Wertz, H [University Medical Center Mannheim, University of Heidelberg, Mannheim, Baden-Wuerttemberg (Germany)

    2015-06-15

    Purpose: Intensity modulated radiotherapy requires a comprehensive quality assurance program in general and ideally independent verification of dose delivery. Since conventional 2D detector arrays allow only pre-treatment verification, there is a debate concerning the need of online dose verification. This study presents the clinical performance, including dosimetric plan verification in 2D as well as in 3D and the error detection abilities of a new transmission detector (TD) for online dose verification of 6MV photon beam. Methods: To validate the dosimetric performance of the new device, dose reconstruction based on TD measurements were compared to a conventional pre-treatment verification method (reference) and treatment planning system (TPS) for 18 IMRT and VMAT treatment plans. Furthermore, dose reconstruction inside the patient based on TD read-out was evaluated by comparing various dose volume indices and 3D gamma evaluations against independent dose computation and TPS. To investigate the sensitivity of the new device, different types of systematic and random errors for leaf positions and linac output were introduced in IMRT treatment sequences. Results: The 2D gamma index evaluation of transmission detector based dose reconstruction showed an excellent agreement for all IMRT and VMAT plans compared to reference measurements (99.3±1.2)% and TPS (99.1±0.7)%. Good agreement was also obtained for 3D dose reconstruction based on TD read-out compared to dose computation (mean gamma value of PTV = 0.27±0.04). Only a minimal dose underestimation within the target volume was observed when analyzing DVH indices (<1%). Positional errors in leaf banks larger than 1mm and errors in linac output larger than 2% could clearly identified with the TD. Conclusion: Since 2D and 3D evaluations for all IMRT and VMAT treatment plans were in excellent agreement with reference measurements and dose computation, the new TD is suitable to qualify for routine treatment plan

  3. Measuring online social bubbles

    Directory of Open Access Journals (Sweden)

    Dimitar Nikolov

    2015-12-01

    Full Text Available Social media have become a prevalent channel to access information, spread ideas, and influence opinions. However, it has been suggested that social and algorithmic filtering may cause exposure to less diverse points of view. Here we quantitatively measure this kind of social bias at the collective level by mining a massive datasets of web clicks. Our analysis shows that collectively, people access information from a significantly narrower spectrum of sources through social media and email, compared to a search baseline. The significance of this finding for individual exposure is revealed by investigating the relationship between the diversity of information sources experienced by users at both the collective and individual levels in two datasets where individual users can be analyzed—Twitter posts and search logs. There is a strong correlation between collective and individual diversity, supporting the notion that when we use social media we find ourselves inside “social bubbles.” Our results could lead to a deeper understanding of how technology biases our exposure to new information.

  4. Measuring consumer perceptions of online shopping convenience

    OpenAIRE

    Ferreira, Margarida Bernardo

    2016-01-01

    The aim of this master thesis is to identify which dimensions of convenience affect consumers’ intention of using online shopping. Also it explores a conceptual model to measuring consumer perceptions of online shopping convenience. This paper contains prospects about online consumer behavior, and the results have important implications for retailers, managers and marketers, related to online shopping strategies. An empirical investigation was carried out to test the hypotheses. In order t...

  5. Measuring Student Engagement in an Online Program

    Science.gov (United States)

    Bigatel, Paula; Williams, Vicki

    2015-01-01

    In an effort to measure the effectiveness of faculty development courses promoting student engagement, the faculty development unit of Penn State's Online Campus conducted a pilot study within a large online Bachelor of Science in Business (BSB) program. In all, 2,296 students were surveyed in the spring and summer semesters of 2014 in order to…

  6. Beam energy online measurement of BEPCII LINAC

    CERN Document Server

    Wang, Shao-Zhe; Chi, Yun-Long

    2015-01-01

    This paper describes beam energy online measurement of BEPCII linac, presents the calculation formula and some of the results. The method mentioned here measures the beam energy by acquiring beam positions in the horizontal direction with three beam position monitors (BPM) eliminating the effect of orbit fluctuation, which is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in the end of this paper.

  7. Online wind turbine measurement laboratory

    DEFF Research Database (Denmark)

    Hansen, K.S.; Helgesen Pedersen, K.O.; Schmidt Paulsen, U.

    2006-01-01

    As part of the International Master of Science Program in Wind Energy at DTU, a complete interactive wind turbine measurement laboratory has been developed. A 500 kW stall regulated wind turbine has been instrumented with sensors for recording 1) turbine operational parameters, 2) meteorological...... conditions, 3) electrical quantities and 4) mechanical loads in terms of strain gauge signals. The data acquisition system has been designed and implemented by Risø together with students and teachers from DTU. It is based on LabVIEW© combined with a MySQL database for data management. The system enables...... calculations and extreme loads estimation in basic wind turbine courses. Power quality analysis is carried out based on high speed sampled, three-phase voltage and current signals. The wide spectrum of sensors enables a detailed study of the correlation between meteorological, mechanical and electrical...

  8. Measuring Online Dialogic Conversations: A Scale Development

    DEFF Research Database (Denmark)

    Romenti, Stefania; Valentini, Chiara; Murtarelli, Grazia;

    2016-01-01

    interactivity. Dialogic conversations are defined as sequences of communicative actions and counteractions taken by social actors for different purposes based on specific linguistic choices and characterised by diverse communicative approaches and the role played by the involved parties. Design......-taking, sequencing of conversation, repair strategies and procedures. Originality/value: This is the first study proposing a systematic measurement of the dialogue orientation of online conversations that takes into consideration the role of language and communicative actions. The proposed measurement offers...

  9. Online measurement of the BEPC Ⅱ background using RadFET dosimeters

    Institute of Scientific and Technical Information of China (English)

    GONG Hui; LI Jin; GONG Guang-Hua; LI Yu-Xiong; HOU Lei; SHAO Bei-Bei

    2009-01-01

    To monitor the integral dose deposited in the BESⅢ electromagnetic calorimeter whose perfor-mance degrades due to exposure to the BEPCⅡ background, a 400 nm IMPL RadFET dosimeter-based integral dose online monitor system is built. After calibration with the 60Co source and verification with TLD in the pulse radiation fields, an experiment was arranged to measure the BEPC Ⅱ background online. The results are presented.

  10. Measurement of radiation dose in dental radiology.

    Science.gov (United States)

    Helmrot, Ebba; Alm Carlsson, Gudrun

    2005-01-01

    Patient dose audit is an important tool for quality control and it is important to have a well-defined and easy to use method for dose measurements. In dental radiology, the most commonly used dose parameters for the setting of diagnostic reference levels (DRLs) are the entrance surface air kerma (ESAK) for intraoral examinations and dose width product (DWP) for panoramic examinations. DWP is the air kerma at the front side of the secondary collimator integrated over the collimator width and an exposure cycle. ESAK or DWP is usually measured in the absence of the patient but with the same settings of tube voltage (kV), tube current (mA) and exposure time as with the patient present. Neither of these methods is easy to use, and, in addition, DWP is not a risk related quantity. A better method of monitoring patient dose would be to use a dose area product (DAP) meter for all types of dental examinations. In this study, measurements with a DAP meter are reported for intraoral and panoramic examinations. The DWP is also measured with a pencil ionisation chamber and the product of DWP and the height H (DWP x H) of the secondary collimator (measured using film) was compared to DAP. The results show that it is feasible to measure DAP using a DAP meter for both intraoral and panoramic examinations. The DAP is therefore recommended for the setting of DRLs.

  11. Brachytherapy dose measurements in heterogeneous tissues

    Energy Technology Data Exchange (ETDEWEB)

    Paiva F, G.; Luvizotto, J.; Salles C, T.; Guimaraes A, P. C.; Dalledone S, P. de T.; Yoriyaz, H. [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil); Rubo, R., E-mail: gabrielpaivafonseca@gmail.com [Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo, 05403-900 Sao Paulo (Brazil)

    2014-08-15

    Recently, Beau lieu et al. published an article providing guidance for Model-Based Dose Calculation Algorithms (MBDCAs), where tissue heterogeneity considerations are addressed. It is well-known that T G-43 formalism which considers only water medium is limited and significant dose differences have been found comparing both methodologies. The aim of the present work is to experimentally quantify dose values in heterogeneous medium using different dose measurement methods and techniques and compare them with those obtained with Monte Carlo simulations. Experiments have been performed using a Nucletron micro Selectron-Hdr Ir-192 brachytherapy source and a heterogeneous phantom composed by PMMA and different tissue equivalent cylinders like bone, lungs and muscle. Several dose measurements were obtained using tissue equivalent materials with height 1.8 cm and 4.3 cm positioned between the radiation source and the detectors. Radiochromic films, TLDs and MOSFET S have been used for the dose measurements. Film dosimetry has been performed using two methodologies: a) linearization for dose-response curve based on calibration curves to create a functional form that linearize s the dose response and b) 177 multichannel analysis dosimetry where the multiple color channels are analyzed allowing to address not only disturbances in the measurements caused by thickness variation in the film layer, but also, separate other external influences in the film response. All experiments have been simulated using the MCNP5 Monte Carlo radiation transport code. Comparison of experimental results are in good agreement with calculated dose values with differences less than 6% for almost all cases. (Author)

  12. Measuring Online Dialogic Conversations: A Scale Development

    DEFF Research Database (Denmark)

    Romenti, Stefania; Valentini, Chiara; Murtarelli, Grazia

    2016-01-01

    Purpose: The scope of this paper is to develop and test a measurement scale for assessing the quality of dialogic conversations among companies and digital publics in social media. It is argued that dialogic conversations are the drivers of dialogic engagement and the result of dialogic....../methodology/approach: A multidimensional scale for measuring dialogic conversations is developed from relevant literature concerning dialogue and public engagement in the fields of corporate communication, public relations, management studies and conversation analysis. The scale was pre-tested to redefine and purify it from irrelevant...... corporate communication managers a concrete tool for evaluating the quality of their online communications and for identifying those areas of their online communication that need improvement....

  13. How should we measure online learning activity?

    Directory of Open Access Journals (Sweden)

    Tim O'Riordan

    2016-07-01

    Full Text Available The proliferation of Web-based learning objects makes finding and evaluating resources a considerable hurdle for learners to overcome. While established learning analytics methods provide feedback that can aid learner evaluation of learning resources, the adequacy and reliability of these methods is questioned. Because engagement with online learning is different from other Web activity, it is important to establish pedagogically relevant measures that can aid the development of distinct, automated analysis systems. Content analysis is often used to examine online discussion in educational settings, but these instruments are rarely compared with each other which leads to uncertainty regarding their validity and reliability. In this study, participation in Massive Open Online Course (MOOC comment forums was evaluated using four different analytical approaches: the Digital Artefacts for Learning Engagement (DiAL-e framework, Bloom's Taxonomy, Structure of Observed Learning Outcomes (SOLO and Community of Inquiry (CoI. Results from this study indicate that different approaches to measuring cognitive activity are closely correlated and are distinct from typical interaction measures. This suggests that computational approaches to pedagogical analysis may provide useful insights into learning processes.

  14. Determination of the delivered hemodialysis dose using standard methods and on-line clearance monitoring

    Directory of Open Access Journals (Sweden)

    Vlatković Vlastimir

    2006-01-01

    Full Text Available Background/aim: Delivered dialysis dose has a cumulative effect and significant influence upon the adequacy of dialysis, quality of life and development of co-morbidity at patients on dialysis. Thus, a great attention is given to the optimization of dialysis treatment. On-line Clearance Monitoring (OCM allows a precise and continuous measurement of the delivered dialysis dose. Kt/V index (K = dialyzer clearance of urea; t = dialysis time; V = patient's total body water, measured in real time is used as a unit for expressing the dialysis dose. The aim of this research was to perform a comparative assessment of the delivered dialysis dose by the application of the standard measurement methods and a module for continuous clearance monitoring. Methods. The study encompassed 105 patients who had been on the chronic hemodialysis program for more than three months, three times a week. By random choice, one treatment per each controlled patient was taken. All the treatments understood bicarbonate dialysis. The delivered dialysis dose was determined by the calculation of mathematical models: Urea Reduction Ratio (URR singlepool index Kt/V (spKt/V and by the application of OCM. Results. Urea Reduction Ratio was the most sensitive parameter for the assessment and, at the same time, it was in the strongest correlation with the other two, spKt/V indexes and OCM. The values pointed out an adequate dialysis dose. The URR values were significantly higher in women than in men, p < 0.05. The other applied model for the delivered dialysis dose measurement was Kt/V index. The obtained values showed that the dialysis dose was adequate, and that, according to this parameter, the women had significantly better dialysis, then the men p < 0.05. According to the OCM, the average value was slightly lower than the adequate one. The women had a satisfactory dialysis according to this index as well, while the delivered dialysis dose was insufficient in men. The difference

  15. Dose measurements around spallation neutron sources.

    Science.gov (United States)

    Fragopoulou, M; Stoulos, S; Manolopoulou, M; Krivopustov, M; Zamani, M

    2008-01-01

    Neutron dose measurements and calculations around spallation sources appear to be of great importance in shielding research. Two spallation sources were irradiated by high-energy proton beams delivered by the Nuclotron accelerator (JINR), Dubna. Neutrons produced by the spallation sources were measured by using solid-state nuclear track detectors. In addition, neutron dose was calculated after polyethylene and concrete, using a phenomenological model based on empirical relations applied in high-energy physics. The study provides an analytical and experimental neutron benchmark analysis using the transmission factor and a comparison between the experimental results and calculations.

  16. MLHD online : manual for the herbicide dose calculation module

    NARCIS (Netherlands)

    PRI,; Kempenaar, C.

    2004-01-01

    MLHD is short for Minimum Lethal Herbicide Dose. MLHD is a new concept within chemical weed control. It supports effective weed control while herbicide doses are kept at minimum effective levels (minimum lethal doses). This manual describes how to use of the MLHD calculation module for users from ou

  17. Measuring pacemaker dose: A clinical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Studenski, Matthew T., E-mail: matthew.studenski@jeffersonhospital.org [Department of Radiation Oncology at the Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States); Xiao Ying; Harrison, Amy S. [Department of Radiation Oncology at the Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States)

    2012-07-01

    Recently in our clinic, we have seen an increased number of patients presenting with pacemakers and defibrillators. Precautions are taken to develop a treatment plan that minimizes the dose to the pacemaker because of the adverse effects of radiation on the electronics. Here we analyze different dosimeters to determine which is the most accurate in measuring pacemaker or defibrillator dose while at the same time not requiring a significant investment in time to maintain an efficient workflow in the clinic. The dosimeters analyzed here were ion chambers, diodes, metal-oxide-semiconductor field effect transistor (MOSFETs), and optically stimulated luminescence (OSL) dosimeters. A simple phantom was used to quantify the angular and energy dependence of each dosimeter. Next, 8 patients plans were delivered to a Rando phantom with all the dosimeters located where the pacemaker would be, and the measurements were compared with the predicted dose. A cone beam computed tomography (CBCT) image was obtained to determine the dosimeter response in the kilovoltage energy range. In terms of the angular and energy dependence of the dosimeters, the ion chamber and diode were the most stable. For the clinical cases, all the dosimeters match relatively well with the predicted dose, although the ideal dosimeter to use is case dependent. The dosimeters, especially the MOSFETS, tend to be less accurate for the plans, with many lateral beams. Because of their efficiency, we recommend using a MOSFET or a diode to measure the dose. If a discrepancy is observed between the measured and expected dose (especially when the pacemaker to field edge is <10 cm), we recommend analyzing the treatment plan to see whether there are many lateral beams. Follow-up with another dosimeter rather than repeating multiple times with the same type of dosimeter. All dosimeters should be placed after the CBCT has been acquired.

  18. Polystyrene calorimeter for electron beam dose measurements

    DEFF Research Database (Denmark)

    Miller, A.

    1995-01-01

    Calorimeters from polystrene have been constructed for dose measurement at 4-10 MeV electron accelerators. These calorimeters have been used successfully for a few years, and polystyrene calorimeters for use at energies down to 1 MeV and being tested. Advantage of polystyrene as the absorbing...

  19. Measurement and evaluation of internal dose

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae-Young; Chang, S.Y.; Lee, J.I.; Song, M.Y. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    1999-12-01

    This report describes the contents and results for implementation of internal radiation monitoring programme, measurement of uranium lung deposition by lung counter and assessment of committed effective dose for radiation workers of KNFC. The aim of radiation protection was achieved by implementing this activity. 3 refs., 6 tabs. (Author)

  20. Measurement and evaluation of internal dose

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae Young; Chang, S. Y.; Lee, J. I.; Song, M. Y. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-01-01

    This report describes the contents and results for implementation of internal radiating monitoring programme, measurement of uranium present in lung by lung counter and assessment of committed effective dose for radiation workers of KNFC. The aim of radiation protection was achieved by implementing this activity. 8 refs., 14 tabs. (Author)

  1. Measurement and evaluation of internal dose

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae Young; Chang, S.Y.; Lee, J.I.; Song, M.Y. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2001-01-01

    This report describes the contents and results for implementation of internal radiation monitoring programme, measurement of uranium present in lung by lung counter and assessment of committed effective dose for radiation workers of KNFC. The aim of radiation protection was achieved by implementing this activity. 4 refs., 12 tabs. (Author)

  2. Online haemodiafiltration: definition, dose quantification and safety revisited.

    Science.gov (United States)

    Tattersall, James E; Ward, Richard A

    2013-03-01

    The general objective assigned to the EUropean DIALlysis (EUDIAL) Working Group by the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) was to enhance the quality of dialysis therapies in Europe in the broadest possible sense. Given the increasing interest in convective therapies, the Working Group has started by focusing on haemodiafiltration (HDF) therapies. Several reports suggest that those therapies potentially improve the outcomes for end-stage renal disease patients. Europe is the leader in the field, having introduced the concept of ultra-purity for water and dialysis fluids and with notified bodies of the European Community having certified water treatment systems and online HDF machines. The prevalence of online HDF-treated patients is steadily increasing in Europe, averaging 15%. A EUDIAL consensus conference was held in Paris on 13 October 2011 to revisit terminology, safety and efficacy of online HDF. This is the first report of the expert group arising from that conference.

  3. Online Distributed Fault Detection of Sensor Measurements

    Institute of Scientific and Technical Information of China (English)

    GAO Jianliang; XU Yongjun; LI Xiaowei

    2007-01-01

    In wireless sensor networks (WSNs), a faulty sensor may produce incorrect data and transmit them to the other sensors. This would consume the limited energy and bandwidth of WSNs. Furthermore, the base station may make inappropriate decisions when it receives the incorrect data sent by the faulty sensors. To solve these problems, this paper develops an online distributed algorithm to detect such faults by exploring the weighted majority vote scheme. Considering the spatial correlations in WSNs, a faulty sensor can diagnose itself through utilizing the spatial and time information provided by its neighbor sensors. Simulation results show that even when as many as 30% of the sensors are faulty, over 95% of faults can be correctly detected with our algorithm. These results indicate that the proposed algorithm has excellent performance in detecting fault of sensor measurements in WSNs.

  4. A Comparison of Performance Measures via Online Search

    CERN Document Server

    Boyar, Joan; Maiti, Abyayananda

    2011-01-01

    Though competitive analysis has been a very useful performance measure for the quality of online algorithms, it is recognized that it sometimes fails to distinguish between algorithms of different quality in practice. A number of alternative measures have been proposed, but, with a few exceptions, these have generally been applied only to the online problem they were developed in connection with. Recently, a systematic study of performance measures for online algorithms was initiated [Boyar, Irani, Larsen: Eleventh International Algorithms and Data Structures Symposium 2009], first focusing on a simple server problem. We continue this work by studying a fundamentally different online problem, online search, and the Reservation Price Policies in particular. The purpose of this line of work is to learn more about the applicability of various performance measures in different situations and the properties that the different measures emphasize. We investigate the following analysis techniques: Competitive, Relati...

  5. Scintillation spectroscopy for beta ray dose measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vapirev, E.I.; Jordanov, T.; Amin, S.; Stoilov, N.; Georgieva, K. [Sofia Univ. (Bulgaria). Fizicheski Fakultet

    1996-11-01

    Two methods have been developed and tested for the measurement of beta ray dose with a scintillation probe. According to the first method the energy absorbed in plastic filters is calculated from the difference between the energy E of the incident and filtered beta spectrum with an expression of the type E {approx} c{Sigma}iN(i)/{Delta}m, where c is a calibration constant (keV per channel), i is the channel number, N(i) is the detected beta spectrum, and {Delta}m is the filter thickness. According to the second `dE/dx` method the energy deposited in the surface layer of the scintillator is calculated by E {approx} c{Sigma}dE/dx(i)N(i), where dE/dx is the specific energy loss for tissue-equivalent media. The methods were tested for the cases of normally incident electrons and surface contamination. The scintillation probe used is stillbene and the test sources are thin {sup 90}Sr/{sup 90}Y and {sup 137}Cs. The results are close to the expected doses as calculated by Monte Carlo simulations. (Author).

  6. Design and Study of Data Acquisition System for Pulsed γ Dose Measurement Device

    Institute of Scientific and Technical Information of China (English)

    DOU; Yu-ling; YANG; Shao-hua; ZHANG; Guo-guang

    2012-01-01

    <正>A data acquisition system for online pulsed gamma dose measurement device was designed and developed (Fig. 1), and its performance was tested. The results show that the data acquisition system in both the continued and pulsed input, output electric charges and input energy have a good linear relationship. Experiments were done respectively on the XRS-3 pulsed source and re-frequency

  7. Measuring Student Engagement in the Online Course: The Online Student Engagement Scale (OSE)

    Science.gov (United States)

    Dixson, Marcia D.

    2015-01-01

    Student engagement is critical to student learning, especially in the online environment, where students can often feel isolated and disconnected. Therefore, teachers and researchers need to be able to measure student engagement. This study provides validation of the Online Student Engagement scale (OSE) by correlating student self-reports of…

  8. Online dose reconstruction for tracked volumetric arc therapy: Real-time implementation and offline quality assurance for prostate SBRT.

    Science.gov (United States)

    Kamerling, Cornelis Ph; Fast, Martin F; Ziegenhein, Peter; Menten, Martin J; Nill, Simeon; Oelfke, Uwe

    2017-08-20

    Firstly, this study provides a real-time implementation of online dose reconstruction for tracked volumetric arc therapy (VMAT). Secondly, this study describes a novel offline quality assurance tool, based on commercial dose calculation algorithms. Online dose reconstruction for VMAT is a computationally challenging task in terms of computer memory usage and calculation speed. To potentially reduce the amount of memory used, we analyzed the impact of beam angle sampling for dose calculation on the accuracy of the dose distribution. To establish the performance of the method, we planned two single-arc VMAT prostate stereotactic body radiation therapy cases for delivery with dynamic MLC tracking. For quality assurance of our online dose reconstruction method we have also developed a stand-alone offline dose reconstruction tool, which utilizes the RayStation treatment planning system to calculate dose. For the online reconstructed dose distributions of the tracked deliveries, we could establish strong resemblance for 72 and 36 beam co-planar equidistant beam samples with less than 1.2% deviation for the assessed dose-volume indicators (clinical target volume D98 and D2, and rectum D2). We could achieve average runtimes of 28-31 ms per reported MLC aperture for both dose computation and accumulation, meeting our real-time requirement. To cross-validate the offline tool, we have compared the planned dose to the offline reconstructed dose for static deliveries and found excellent agreement (3%/3 mm global gamma passing rates of 99.8%-100%). Being able to reconstruct dose during delivery enables online quality assurance and online replanning strategies for VMAT. The offline quality assurance tool provides the means to validate novel online dose reconstruction applications using a commercial dose calculation engine. © 2017 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  9. On-line MR imaging for dose validation of abdominal radiotherapy

    Science.gov (United States)

    Glitzner, M.; Crijns, S. P. M.; de Senneville, B. Denis; Kontaxis, C.; Prins, F. M.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2015-11-01

    For quality assurance and adaptive radiotherapy, validation of the actual delivered dose is crucial. Intrafractional anatomy changes cannot be captured satisfactorily during treatment with hitherto available imaging modalitites. Consequently, dose calculations are based on the assumption of static anatomy throughout the treatment. However, intra- and interfraction anatomy is dynamic and changes can be significant. In this paper, we investigate the use of an MR-linac as a dose tracking modality for the validation of treatments in abdominal targets where both respiratory and long-term peristaltic and drift motion occur. The on-line MR imaging capability of the modality provides the means to perform respiratory gating of both delivery and acquisition yielding a model-free respiratory motion management under free breathing conditions. In parallel to the treatment, the volumetric patient anatomy was captured and used to calculate the applied dose. Subsequently, the individual doses were warped back to the planning grid to obtain the actual dose accumulated over the entire treatment duration. Ultimately, the planned dose was validated by comparison with the accumulated dose. Representative for a site subject to breathing modulation, two kidney cases (25 Gy target dose) demonstrated the working principle on volunteer data and simulated delivery. The proposed workflow successfully showed its ability to track local dosimetric changes. Integration of the on-line anatomy information could reveal local dose variations  -2.3-1.5 Gy in the target volume of a volunteer dataset. In the adjacent organs at risk, high local dose errors ranging from  -2.5 to 1.9 Gy could be traced back.

  10. A comparison of performance measures for online algorithms

    DEFF Research Database (Denmark)

    Boyar, Joan; Irani, Sandy; Larsen, Kim Skak

    2009-01-01

    This paper provides a systematic study of several recently suggested measures for online algorithms in the context of a specific problem, namely, the two server problem on three colinear points. Even though the problem is simple, it encapsulates a core challenge in online algorithms which is to b...

  11. Measuring the Community in Online Classes

    Science.gov (United States)

    Rubin, Beth; Fernandes, Ronald

    2013-01-01

    This paper proposes both theoretical and empirical approaches to differentiating the community of inquiry (CoI) in online classes at individual and group levels. Following the example of research on organizational climate, it assesses the strength of shared perceptions of teaching presence, social presence, and cognitive presence. The paper…

  12. Online software for the estimation of fetal radiation dose to patients and staff members in diagnostic radiology;Sistema online para o calculo de doses fetais de pacientes e trabalhadoras ocupacionalmente expostas em radiologia diagnostica

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Paulo Roberto; Groff, Sybele Guedes de Paulo, E-mail: pcosta@if.usp.b [Universidade de Sao Paulo (DFN/IFUSP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear

    2009-07-01

    An online software, named 'Dose Fetal Web', which calculates the dose of the fetus and the radiological risks from both medical and occupational exposures of pregnant women is described. The software uses a mathematical methodology where coefficients for converting uterus to fetal dose, NUD, have been calculated by using Monte Carlo simulation. In the fetal dose from diagnostic medical examination of the pregnant patient, database information regarding output and other equipment related to parameters from the QA database, maternal and fetal parameters collected by ultrasound procedures were used for the fetal dose estimation. In the case of fetal dose of the pregnant staff member the database information regarding routine individual monitoring dosimetry, such as occupational dose and workload, were used for the estimation. In the first case suppose a 26 weeks pregnant patient had to undergo a single AP abdomen procedure (70 kVp peak tube voltage and total filtration 3mmAl), the fetal dose calculated by the software was 4.61 mGy and the radiological risks would be 5.0{center_dot}10{sup -4} and 0.14 to the probability of mental retardation induction and decline in the IQ score, respectively. In the second case, considering that the staff member can be pregnant, and assuming that she wore a 0,5 mm lead equivalent apron during every interventional radiology procedure and a personal dosimetry reading of 2 mGy{sub TLD}/month measured with the TLDs outside the apron, the fetal dose calculated by the software was 0.02 mSv/month. (author)

  13. Design of a new tracking device for on-line dose monitor in ion therapy

    CERN Document Server

    Traini, Giacomo; Bollella, Angela; Collamati, Francesco; De Lucia, Erika; Faccini, Riccardo; Ferroni, Fernando; Frallicciardi, Paola Maria; Mancini-Terracciano, Carlo; Marafini, Michela; Mattei, Ilaria; Miraglia, Federico; Muraro, Silvia; Paramatti, Riccardo; Piersanti, Luca; Pinci, Davide; Rucinski, Antoni; Russomando, Andrea; Sarti, Alessio; Sciubba, Adalberto; Senzacqua, Martina; Solfaroli-Camillocci, Elena; Toppi, Marco; Voena, Cecilia; Patera, Vincenzo

    2016-01-01

    Charged Particle Therapy is a technique for cancer treatment that exploits hadron beams, mostly protons and carbons. A critical issue is the monitoring of the dose released by the beam to the tumor and to the surrounding tissues. We present the design of a new tracking device for monitoring on-line the dose in ion therapy through the detection of secondary charged particles produced by the beam interactions in the patient tissues. In fact, the charged particle emission shape can be correlated with the spatial dose release and the Bragg peak position. The detector uses the information provided by 12 layers of scintillating fibers followed by a plastic scintillator and a small calorimeter made of a pixelated Lutetium Fine Silicate crystal. Simulations have been performed to evaluate the achievable spatial resolution and a possible application of the device for the monitoring of the dose pro?le in a real treatment is presented.

  14. Towards robust deconvolution of low-dose perfusion CT: sparse perfusion deconvolution using online dictionary learning.

    Science.gov (United States)

    Fang, Ruogu; Chen, Tsuhan; Sanelli, Pina C

    2013-05-01

    Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular diseases, particularly in acute stroke and vasospasm. However, the post-processed parametric maps of blood flow tend to be noisy, especially in low-dose CTP, due to the noisy contrast enhancement profile and the oscillatory nature of the results generated by the current computational methods. In this paper, we propose a robust sparse perfusion deconvolution method (SPD) to estimate cerebral blood flow in CTP performed at low radiation dose. We first build a dictionary from high-dose perfusion maps using online dictionary learning and then perform deconvolution-based hemodynamic parameters estimation on the low-dose CTP data. Our method is validated on clinical data of patients with normal and pathological CBF maps. The results show that we achieve superior performance than existing methods, and potentially improve the differentiation between normal and ischemic tissue in the brain.

  15. Estimating thyroid dose in pediatric CT exams from surface dose measurement

    Science.gov (United States)

    Al-Senan, Rani; Mueller, Deborah L.; Hatab, Mustapha R.

    2012-07-01

    The purpose of this study was to investigate the possibility of estimating pediatric thyroid doses from CT using surface neck doses. Optically stimulated luminescence dosimeters were used to measure the neck surface dose of 25 children ranging in ages between one and three years old. The neck circumference for each child was measured. The relationship between obtained surface doses and thyroid dose was studied using acrylic phantoms of various sizes and with holes of different depths. The ratios of hole-to-surface doses were used to convert patients' surface dose to thyroid dose. ImPACT software was utilized to calculate thyroid dose after applying the appropriate age correction factors. A paired t-test was performed to compare thyroid doses from our approach and ImPACT. The ratio of thyroid to surface dose was found to be 1.1. Thyroid doses ranged from 20 to 80 mGy. Comparison showed no statistical significance (p = 0.18). In addition, the average of surface dose variation along the z-axis in helical scans was studied and found to range between 5% (in 10 cm diameter phantom/24 mm collimation/pitch 1.0) and 8% (in 16 cm diameter phantom/12 mm collimation/pitch 0.7). We conclude that surface dose is an acceptable predictor for pediatric thyroid dose from CT. The uncertainty due to surface dose variability may be reduced if narrower collimation is used with a pitch factor close to 1.0. Also, the results did not show any effect of thyroid depth on the measured dose.

  16. A Critical Perspective on Online Safety Measures

    Directory of Open Access Journals (Sweden)

    Elza Dunkels

    2010-06-01

    Full Text Available The Nordic countries have enjoyed mass use of the Internet at home and in schools since the mid-1990’s. Children have been noted to have rapidly taken the Internet into possession and to have made use of the affordances (Greeno, 1994 of Internet communication. However, media coverage of how children take on, and learn what the Internet has to offer has often been of a negative kind. Blazing headlines portray a generation in bottomless danger where children are defined both as possible victims and perpetrators. Another common attribute of this media coverage is the exoticising of young people’s net cultures – describing the young and their cultures as profoundly different from earlier generations and elevating the “colourful and the bizarre” (Coffey et al., 1999, p. 169 to a level where it appears normal for this particular generation. In this setting safe use guides – tips for parents and children on how to keep safe on the Internet – began to appear. They were often composed by teachers, concerned parents, non-governmental organisations and in some cases governments. The safe use guides were disseminated online in different forums aimed at concerned adults. In this article I will give a brief description of current online safety issues and examine them critically. My earlier research – 104 interviews with 12-year old Swedes conducted in 2004-2005 (Dunkels, 2007 and a study of European safe use guides conducted in 2008 (Lüders et al., 2009 left me with a number of questions. I could see that safe use guides were strikingly similar, despite their origin, and I could see that they rested upon norms and values that were actually neither accounted for nor even declared. This article is a literature review of the area with the aim of critically discussing some of these questions.

  17. The transit dose component of high dose rate brachytherapy: Direct measurements and clinical implications

    Energy Technology Data Exchange (ETDEWEB)

    Bastin, K.T.; Podgorsak, M.B.; Thomadsen, B.R. (Univ. of Wisconsin Hospitals and Clinics, Madison, WI (United States))

    1993-07-15

    The purpose was to measure the transit dose produced by a moving high dose rate brachytherapy source and assess its clinical significance. The doses produced from source movement during Ir-192 HDR afterloading were measured using calibrated thermoluminescent dosimeter rods. Transit doses at distances of 0.5-4.0 cm from an endobronchial applicator were measured using a Lucite phantom accommodating 1 x 1 x 6 mm thermoluminescent rods. Surface transit dose measurements were made using esophageal and endobronchial catheters, a gynecologic tandem, and an interstitial needle. No difference was detected in thermoluminescent dosimeter rod responses to 4 MV and Ir-192 spectra (427 nC/Gy) in a range of dose between 2 and 300 cGy. The transit dose at 0.5 cm from an endobronchial catheter was 0.31 cGy/(Curie-fraction) and followed an inverse square fall-off with increasing distance. Surface transit doses ranged from 0.38 cGy/(Curie-fraction) for an esophageal catheter to 1.03 cGy/(Curie-fraction) for an endobronchial catheter. Source velocity is dependent on the interdwell distance and varies between 220-452 mm/sec. A numeric algorithm was developed to calculate total transit dose, and was based on a dynamic point approximation for the moving high dose rate source. This algorithm reliably predicted the empirical transit doses and demonstrated that total transit dose is dependent on source velocity, number of fractions, and source activity. Surface transit doses are dependent on applicator diameter and wall material and thickness. Total transit doses within or outside the desired treatment volume are typically <100 cGy, but may exceed 200 cGy when using a large number of fractions with a high activity source. 9 refs., 8 figs., 1 tab.

  18. USING EYE TRACKING TO MEASURE ONLINE INTERACTIVITY: A THEORETICAL FRAMEWORK

    Directory of Open Access Journals (Sweden)

    Adriana-Emilia ROBU

    2013-06-01

    Full Text Available Notwithstanding that each and every company, even the sweetshop around the corner has found its way to the Internet, some customers still hesitate to shop online or to shop from one site and ignore the other. In order to build an online effective communication between the participants, one of the most important factors is interactivity. In the last decade it received extensive attention in the marketing literature, but few are the studies which have seen new methods to measure it. Eye tracking technology has been broadly used in the cognitive sciences. The purpose of this study is to investigate the existing literature in order to give insights into the eye tracking methodology when measuring the online interactivity. It also describes the eye tracking technology in general, extracts various examples from the eye tracking research field, with different applications, highlights its importance when analyzing the online consumer behavior, giving examples from various studies and finds the key points of the methodological difficulties. Finally, this work has an important merit for the future studies when taking into consideration the eye tracking technology in the online interactivity research and further, it is relevant for marketers, regarding the enhancement of online interactive interfaces and web or mobile applications.

  19. Accredited dose measurements for validation of radiation sterilized products

    DEFF Research Database (Denmark)

    Miller, A.

    1993-01-01

    The activities and services of the accredited Risø High Dose Reference Laboratory are described. The laboratory operates according to the European standard EN 45001 regarding Operation of Testing Laboratories, and it fulfills the requirements of being able to deliver traceable dose measurements f...... of the dosimetric parameters of an irradiation facility. 5. 5. Measurement of absorbed dose distribution in irradiated products. The paper describes these services and the procedures necessary for their execution....

  20. ONLINE GRINDING WHEEL WEAR COMPENSATION BY IMAGE BASED MEASURING TECHNIQUES

    Institute of Scientific and Technical Information of China (English)

    WAN Daping; HU Dejin; WU Qi; ZHANG Yonghong

    2006-01-01

    Automatic compensation of grinding wheel wear in dry grinding is accomplished by an image based online measurement method. A kind of PC-based charge-coupled device image recognition system is schemed out, which detects the topography changes of the grinding wheel surface. Profile data, which corresponds to the wear and the topography, is measured by using a digital image processing method. The grinding wheel wear is evaluated by analyzing the position deviation of the grinding wheel edge. The online wear compensation is achieved according to the measure results. The precise detection and automatic compensation system is integrated into an open structure CNC curve grinding machine. A practical application is carried out to fulfil the precision curve grinding. The experimental results confirm the benefits of the proposed techniques, and the online detection accuracy is less than 5 μm. The grinding machine provides higher precision according to the in-process grinding wheel error compensation.

  1. COMPARING MEASURED AND CALCULATED DOSES IN INTERVENTIONAL CARDIOLOGY PROCEDURES.

    Science.gov (United States)

    Oliveira da Silva, M W; Canevaro, L V; Hunt, J; Rodrigues, B B D

    2017-03-16

    Interventional cardiology requires complex procedures and can result in high doses and dose rates to the patient and medical staff. The many variables that influence the dose to the patient and staff include the beam position and angle, beam size, kVp, filtration, kerma-area product and focus-skin distance. A number of studies using the Monte Carlo method have been undertaken to obtain prospective dose assessments. In this paper, detailed irradiation scenarios were simulated mathematically and the resulting dose estimates were compared with real measurements made previously under very similar irradiation conditions and geometries. The real measurements and the calculated doses were carried out using or simulating an interventional cardiology system with a flat monoplane detector installed in a dedicated room with an Alderson phantom placed on the procedure table. The X-ray spectra, beam angles, focus-skin distance, measured kerma-area product and filtration were simulated, and the real dose measurements and calculated doses were compared. It was shown that the Monte Carlo method was capable of reproducing the real dose measurements within acceptable levels of uncertainty.

  2. On-Line Voltage Stability Assessment based on PMU Measurements

    DEFF Research Database (Denmark)

    Garcia-Valle, Rodrigo; P. Da Silva, Luiz C.; Nielsen, Arne Hejde

    2009-01-01

    through statistic analysis. During the off-line analysis, a memory of high-risk situations following a pre-defined voltage stability criterion is obtained. Thereafter, basic statistics analyses are applied resulting in the definition of voltage regions. During on-line operation, voltage magnitudes......This paper presents a method for on-line monitoring of risk voltage collapse based on synchronised phasor measurement. As there is no room for intensive computation and analysis in real-time, the method is based on the combination of off-line computation and on-line monitoring, which are correlated...... of critical buses obtained by phasor measurements are monitored in relation to the risk regions. Comprehensive studies demonstrate that the proposed method could assist operators to avoid voltage collapse events, by taking preventive or emergency actions....

  3. High dose rate brachytherapy source measurement intercomparison.

    Science.gov (United States)

    Poder, Joel; Smith, Ryan L; Shelton, Nikki; Whitaker, May; Butler, Duncan; Haworth, Annette

    2017-06-01

    This work presents a comparison of air kerma rate (AKR) measurements performed by multiple radiotherapy centres for a single HDR (192)Ir source. Two separate groups (consisting of 15 centres) performed AKR measurements at one of two host centres in Australia. Each group travelled to one of the host centres and measured the AKR of a single (192)Ir source using their own equipment and local protocols. Results were compared to the (192)Ir source calibration certificate provided by the manufacturer by means of a ratio of measured to certified AKR. The comparisons showed remarkably consistent results with the maximum deviation in measurement from the decay-corrected source certificate value being 1.1%. The maximum percentage difference between any two measurements was less than 2%. The comparisons demonstrated the consistency of well-chambers used for (192)Ir AKR measurements in Australia, despite the lack of a local calibration service, and served as a valuable focal point for the exchange of ideas and dosimetry methods.

  4. User Contribution Measurement in Online Forum with Fraud Immunity

    Directory of Open Access Journals (Sweden)

    Guo-Ying Wang

    2013-01-01

    Full Text Available It's very important to reward the contributive users of online forums, for that almost all contents are provided by users in such forums. There should be some rewards for contributive users, and rewards should be proportional to the contributions. So the determination and measurement of user contributions are needed in online forums. At the same time, some users may do some fake contributions to obtain more rewards. In this paper, we analyzed possible frauds in online forum, examined features of each kind of fraud, and proposed some fraud-tolerant parameters according the features of frauds. Results of our experiment show that almost 81% users in the examined online forum have fraudulent activities and pure advertising users can be discovered according to the fraud-tolerant parameters we considered. On the other hand, the experiment results also show that the biggest count of fraud type detected is with the parameter minimum intervals of posts from the same users, and followed by the parameter minimum length of posts. While minimum average rate value of post after specified rates is the parameter that was used for least times. Based on the idea of this paper, frauds of user contributions could be discriminated well, and user contributions can be measured quantitatively and fraud-tolerantly, which provides a basis for online forums to reward users in various ways.

  5. On-line phase space measurement with kicker excitation

    Science.gov (United States)

    Dietrich, J.; Maier, R.; Mohos, I.

    1998-12-01

    A new method for on-line phase space measurements with kicker excitation at COSY was developed. The position data were measured using the analog output of two beam position monitors (BPMs) and directly monitored on a digital storage oscilloscope with an external clock (bunch-synchronous sampling). Nonlinear behavior of the proton beam was visible as well as were resonance islands. Typical measurements are presented.

  6. ONLINE MEASUREMENT OF THE PROGRESS OF DECONTAMINATION

    Energy Technology Data Exchange (ETDEWEB)

    M.A. Ebadian, Ph.D.

    1999-01-01

    In order to determine if the sensor technology and the decontamination technology will face problems once integrated, a feasibility study (see Appendix B) was produced in which the effect of motion on the efficiency of a radiation sensor was measured. It was found that the effect is not negligible; however, it is not catastrophic, and if the sensors are properly calibrated, this obstacle can be overcome. During the first year of this project, many important tasks have been accomplished. The search for radiation sensors provided knowledge on the technologies commercially available. This, in turn, allowed for a proper assessment of the properties, limitations, different methods of measurement, and requirements of a large number of sensors. The best possible characterization and data collection instrument and decontamination technologies were chosen using the requirement information in Appendix A. There are technical problems with installing sensors within the blasting head, such as steel shot and dust interference. Therefore, the sensor array is placed so that it will measure the radioactivity after the blasting. Sensors are rather sensitive, and therefore it is not feasible to place the sensor windows in such an abrasive environment. Other factors, such as the need for radiation hardening in extreme cases, and the possible interference of gamma rays with the radio frequency modem, have been considered. These factors are expected to be negligible and can be revisited at the time of prototype production. Factors that need to be addressed are the vibrations of the blasting unit and how to isolate the sensor array from these. In addition, an electromagnetic survey must be performed to ensure there will be no interference with the electronic component that will be integrated. The integration design is shown in section 4.0.

  7. Development of Real-Time Measurement of Effective Dose for High Dose Rate Neutron Fields

    CERN Document Server

    Braby, L A; Reece, W D

    2003-01-01

    Studies of the effects of low doses of ionizing radiation require sources of radiation which are well characterized in terms of the dose and the quality of the radiation. One of the best measures of the quality of neutron irradiation is the dose mean lineal energy. At very low dose rates this can be determined by measuring individual energy deposition events, and calculating the dose mean of the event size. However, at the dose rates that are normally required for biology experiments, the individual events can not be separated by radiation detectors. However, the total energy deposited in a specified time interval can be measured. This total energy has a random variation which depends on the size of the individual events, so the dose mean lineal energy can be calculated from the variance of repeated measurements of the energy deposited in a fixed time. We have developed a specialized charge integration circuit for the measurement of the charge produced in a small ion chamber in typical neutron irradiation exp...

  8. On-line measurement of heat of combustion

    Science.gov (United States)

    Chaturvedi, S. K.; Chegini, H.

    1988-01-01

    An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate at a level consistent with the desired oxygen concentration in the products. The heat of combustion is determined from a known correlation with the gas volumetric flow rate. An on-line microcomputer accesses the gas volumetric flow data, and displays the heat of combustion values at desired time intervals.

  9. Online SAG Mill Pluse Measurement and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Raj Rajamani; Jose Delgadillo; Vishal Duriseti

    2007-06-30

    The grinding efficiency of semi autogenous milling or ball milling depends on the tumbling motion of the total charge within the mill. Utilization of this tumbling motion for efficient breakage of particles depends on the conditions inside the mill. However, any kind of monitoring device to measure the conditions inside the mill shell during operation is virtually impossible due to the severe environment presented by the tumbling charge. An instrumented grinding ball, which is capable of surviving a few hours and transmitting the impacts it experiences, is proposed here. The spectrum of impacts collected over 100 revolutions of the mills presents the signature of the grinding environment inside mill. This signature could be effectively used to optimize the milling performance by investigating this signature's relation to mill product size, mill throughput, make-up ball size, mill speed, liner profile and ball addition rates. At the same time, it can also be used to design balls and liner systems that can survive longer in the mill. The technological advances made in electronics and communication makes this leap in instrumentation certainly viable. Hence, the instrumented grinding ball offers the ability to qualitatively observe and optimize the milling environment. An instrumented load cell package that can measure the force of impacts inside the grinding chamber of a mill is developed here. The signal from the instrumented load cell package is interpreted in terms of a histogram termed as an impact spectrum which is a plot of the number of impacts at a specific energy level against the energy. It reflects on the average force regime of the mill. The instrumented load cell package was calibrated against the ultra fast load cell which has been unanimously accepted as a standard to measure single breakage events. The load cell package was successfully used to produce impact spectra in an 8.5 inch lab scale mill. The mill speed and the ball size were varied to

  10. The Antiproton Depth Dose Curve Measured with Alanine Detectors

    DEFF Research Database (Denmark)

    Bassler, Niels; Hansen, Johnny Witterseh; Palmans, Hugo;

    2008-01-01

    In this paper we report on the measurement of the antiproton depth dose curve, with alanine detectors. The results are compared with simulations using the particle energy spectrum calculated by FLUKA, and using the track structure model of Hansen et Olsen for conversion of calculated dose...

  11. Measurements of neutron dose rates with a balloon in Japan.

    Science.gov (United States)

    Nagaoka, K; Hiraide, I; Sato, K; Yamagami, T; Nakamura, T; Yabutani, T

    2007-01-01

    Measurements of cosmic-ray neutron dose rates with a balloon in Sanriku, Japan (geographic location: 39 degrees N, 142 degrees E; corresponding geomagnetic latitude: 30 degrees N) were conducted at an altitude from 0.2 to 25 km on 25-26 August 2004 when solar activity was at an average level. Neutron dose rates given as ambient dose equivalent rates (H(10)) were measured with high-sensitive neutron dose equivalent counters and electronic silicon personal dosimeters (EPDs). The neutron dose rates increased with increasing altitude, but they were saturated around 15-20 km and decreased with increasing altitude beyond 20 km. The neutron ambient dose equivalent rate was 1.5 microSv/h(- 1) at 20 km. Measured values were corrected for the deviation of the energy response of the dose equivalent counter from the fluence-to-ambient dose equivalent conversion coefficient, and the corrected values were very close to the calculated values with EPCARD. On the other hand, neutron measurements by the EPDs gave about 10 times overestimation because of the high sensitivity to cosmic-ray protons.

  12. Sequential measurements of environmental neutron energy spectrum and neutron dose

    Energy Technology Data Exchange (ETDEWEB)

    Nunomiya, Tomoya; Nakamura, Takashi; Suzuki, Hiroyuki; Terunuma, Kazutaka; Hirabayashi, Naoya; Sato, Youichi; Abe, Sigeru; Rasolonjatovo A.H, Danielle [Tohoku Univ., Dept. of Quantum Science and Energy Engineering, Sendai, Miyagi (Japan)

    2003-03-01

    From April 2001, neutron energy spectra and neutron dose were sequentially measured using 5'' -rem counter and {sup 3}He multi-moderator spectrometer (Boner boll) at Kawauchi-campus of Tohoku University. These data were collected about the relation between the dose level and the solar activities. (author)

  13. Uncertainty of dose measurement in radiation processing

    DEFF Research Database (Denmark)

    Miller, A.

    1996-01-01

    The major standard organizations of the world have addressed the issue of reporting uncertainties in measurement reports and certificates. There is, however, still some ambiguity in the minds of many people who try to implement the recommendations in real life. This paper is a contribution...... to the running debate and presents the author's view, which is based upon experience in radiation processing dosimetry. The origin of all uncertainty components must be identified and can be classified according to Type A and Type B, but it is equally important to separate the uncertainty components into those...... that contribute to the observable uncertainty of repeated measurements and those that do not. Examples of the use of these principles are presented in the paper....

  14. On-line Measuring Method for Shell Chamber Volume

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-zhong; WANG De-min; JIANG Tao; CAO Guo-hua; WANG Qi

    2005-01-01

    Using the ideal gas state equation, an on-line measuring method for the shell chamber volume is studied in this paper. After analyzing how various measurement parameters affect the measurement accuracy, the system parameters are optimized in this method. Because the shape and volume of the tested items are similar, the method of using "tamping" to raise the accuracy and speed of the measurement is put forward. Based on the work above, a prototype of the testing instrument for shell chamber volume was developed, automatically testing and controlling. Compared with the method of "water weight", this method is more accurate, quicker and more automotive, so it is adaptable for the use of on-line detection.

  15. Measurement of absorbed dose and proposed radiation exposure level

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Takayuki; Koizumi, Masayuki; Furukawa, Tomo [Tokai Univ., Isehara, Kanagawa (Japan). Hospital

    2003-03-01

    Absorbed dose was measured in clinical X-ray examinations using thermoluminescence dosimeter (TLD). Moreover, we distributed the levels of radiation exposure into 3 classes. The presumed dose of the internal organs, e.g., uterus dose, was computed to depth doses with a surface dose. This information provides a prediction of the influence of radiation, and the examination can be performed with the informed consent of the patient. Moreover, we examined the distribution of the level of absorbed dose. We proposed two kinds of radiation exposure level, one to the fetus in a pregnant woman and a general level of radiation exposure that is not applied to pregnant women. The levels were as follows: 0.5 mGy and 100 mGy were considered the boundaries for fetal radiation exposure in a pregnant woman, and 200 mGy and 3 Gy were considered the boundaries for the general level of radiation exposure (excluding pregnant women). (author)

  16. [Dose-effect measurements as a basis for computer-assisted dose distribution planning in brachytherapy].

    Science.gov (United States)

    Fichte, B; Schumann, E

    1984-05-01

    A measuring unit is presented for the measurement of dose rate values around an iridium-192 source. The values determined by measurements are compared to the calculated values. Both show a good conformity, so they can be used as basis for a computer program.

  17. Student's music exposure: Full-day personal dose measurements.

    Science.gov (United States)

    Washnik, Nilesh Jeevandas; Phillips, Susan L; Teglas, Sandra

    2016-01-01

    Previous studies have shown that collegiate level music students are exposed to potentially hazardous sound levels. Compared to professional musicians, collegiate level music students typically do not perform as frequently, but they are exposed to intense sounds during practice and rehearsal sessions. The purpose of the study was to determine the full-day exposure dose including individual practice and ensemble rehearsals for collegiate student musicians. Sixty-seven college students of classical music were recruited representing 17 primary instruments. Of these students, 57 completed 2 days of noise dose measurements using Cirrus doseBadge programed according to the National Institute for Occupational Safety and Health criterion. Sound exposure was measured for 2 days from morning to evening, ranging from 7 to 9 h. Twenty-eight out of 57 (49%) student musicians exceeded a 100% daily noise dose on at least 1 day of the two measurement days. Eleven student musicians (19%) exceeded 100% daily noise dose on both days. Fourteen students exceeded 100% dose during large ensemble rehearsals and eight students exceeded 100% dose during individual practice sessions. Approximately, half of the student musicians exceeded 100% noise dose on a typical college schedule. This finding indicates that a large proportion of collegiate student musicians are at risk of developing noise-induced hearing loss due to hazardous sound levels. Considering the current finding, there is a need to conduct hearing conservation programs in all music schools, and to educate student musicians about the use and importance of hearing protection devices for their hearing.

  18. Imaging and Measuring Electron Beam Dose Distributions Using Holographic Interferometry

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    Holographic interferometry was used to image and measure ionizing radiation depth-dose and isodose distributions in transparent liquids. Both broad and narrowly collimated electron beams from accelerators (2–10 MeV) provided short irradiation times of 30 ns to 0.6 s. Holographic images and measur......Holographic interferometry was used to image and measure ionizing radiation depth-dose and isodose distributions in transparent liquids. Both broad and narrowly collimated electron beams from accelerators (2–10 MeV) provided short irradiation times of 30 ns to 0.6 s. Holographic images...... and measurements of absorbed dose distributions were achieved in liquids of various densities and thermal properties and in water layers thinner than the electron range and with backings of materials of various densities and atomic numbers. The lowest detectable dose in some liquids was of the order of a few k...

  19. Out-of-field dose measurements in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kaderka, Robert

    2011-07-13

    This thesis describes the results from measurements of the out-of-field dose in radiotherapy. The dose outside the treatment volume has been determined in a water phantom and an anthropomorphic phantom. Measurements were performed with linac photons, passively delivered protons, scanned protons, passively delivered carbon ions as well as scanned carbon ions. It was found that the use of charged particles for radiotherapy reduces the out-of-field dose by up to three orders of magnitude compared to conventional radiotherapy with photons.

  20. On-line Measurements of Settling Charateristics in Activated Sludge

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Larsen, Torben

    1997-01-01

    An on-line settling column for measuring the dynamic variations of settling velocity of activated sludge has been developed. The settling column is automatic and self-cleansing insuring continuous and reliable measurements. The settling column was tested on sludge from a batch reactor where sucrose...... was added as an impulse to activated sludge. The continuous measurement of settling velocity revealed a highly dynamic response after the sucrose was added. The result were verified with simultaneous measurement of the initial settling rate. A 200 hour experiment showed variations in settling velocity...

  1. Concept of proton radiography using energy resolved dose measurement

    Science.gov (United States)

    Bentefour, El H.; Schnuerer, Roland; Lu, Hsiao-Ming

    2016-08-01

    Energy resolved dosimetry offers a potential path to single detector based proton imaging using scanned proton beams. This is because energy resolved dose functions encrypt the radiological depth at which the measurements are made. When a set of predetermined proton beams ‘proton imaging field’ are used to deliver a well determined dose distribution in a specific volume, then, at any given depth x of this volume, the behavior of the dose against the energies of the proton imaging field is unique and characterizes the depth x. This concept applies directly to proton therapy scanning delivery methods (pencil beam scanning and uniform scanning) and it can be extended to the proton therapy passive delivery methods (single and double scattering) if the delivery of the irradiation is time-controlled with a known time-energy relationship. To derive the water equivalent path length (WEPL) from the energy resolved dose measurement, one may proceed in two different ways. A first method is by matching the measured energy resolved dose function to a pre-established calibration database of the behavior of the energy resolved dose in water, measured over the entire range of radiological depths with at least 1 mm spatial resolution. This calibration database can also be made specific to the patient if computed using the patient x-CT data. A second method to determine the WEPL is by using the empirical relationships between the WEPL and the integral dose or the depth at 80% of the proximal fall off of the energy resolved dose functions in water. In this note, we establish the evidence of the fundamental relationship between the energy resolved dose and the WEPL at the depth of the measurement. Then, we illustrate this relationship with experimental data and discuss its imaging dynamic range for 230 MeV protons.

  2. Concept of proton radiography using energy resolved dose measurement.

    Science.gov (United States)

    Bentefour, El H; Schnuerer, Roland; Lu, Hsiao-Ming

    2016-08-21

    Energy resolved dosimetry offers a potential path to single detector based proton imaging using scanned proton beams. This is because energy resolved dose functions encrypt the radiological depth at which the measurements are made. When a set of predetermined proton beams 'proton imaging field' are used to deliver a well determined dose distribution in a specific volume, then, at any given depth x of this volume, the behavior of the dose against the energies of the proton imaging field is unique and characterizes the depth x. This concept applies directly to proton therapy scanning delivery methods (pencil beam scanning and uniform scanning) and it can be extended to the proton therapy passive delivery methods (single and double scattering) if the delivery of the irradiation is time-controlled with a known time-energy relationship. To derive the water equivalent path length (WEPL) from the energy resolved dose measurement, one may proceed in two different ways. A first method is by matching the measured energy resolved dose function to a pre-established calibration database of the behavior of the energy resolved dose in water, measured over the entire range of radiological depths with at least 1 mm spatial resolution. This calibration database can also be made specific to the patient if computed using the patient x-CT data. A second method to determine the WEPL is by using the empirical relationships between the WEPL and the integral dose or the depth at 80% of the proximal fall off of the energy resolved dose functions in water. In this note, we establish the evidence of the fundamental relationship between the energy resolved dose and the WEPL at the depth of the measurement. Then, we illustrate this relationship with experimental data and discuss its imaging dynamic range for 230 MeV protons.

  3. Radiation dose measurement of paediatric patients in Estonia

    Energy Technology Data Exchange (ETDEWEB)

    Kepler, K. [Training Centre of Medical Physics and Biomedical Engineering, University of Tartu (Estonia); Lintrop, M. [Department of Radiology, Tartu University Hospital, Tartu (Estonia); Servomaa, A.; Parviainen, T. [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland); Eek, V.; Filippova, I. [Estonian Radiation Protection Centre, Tallinn (Estonia)

    2003-06-01

    According to the Medical Exposure Directive (97/43/Euratom) the radiation doses to patients should be measured in every hospital and doses should be compared to the reference doses established by the competent authorities. Special attention should be paid to the paediatric x-ray examinations, because the paediatric patients are more radiosensitive than adult patients. The requirement of measurements of radiation dose to patients is not yet included in the Estonian radiation act, but the purpose to join the European Communities makes the quality control in radiology very actual in Estonia. The necessity exists to introduce suitable measurement methods in the Xray departments of Estonian hospitals for establishing feedback system for radiologists, radiographers and medical physicists in optimising the radiation burden of patients and image quality. (orig.)

  4. Measurement of spatial dose distribution for evaluation operator dose during nero-interventional procedures

    Energy Technology Data Exchange (ETDEWEB)

    Han, Su Chul [Division of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Hong, Dong Hee [Dept. of Radiology Science, Far East University, Eumseong (Korea, Republic of)

    2016-09-15

    The spatial dose distribution was measured with ionization chamber as preliminary study to evaluate operator dose and to study dose reduction during neuro-interventional procedures. The zone of operators was divided into four area (45, 135, 225, and 315 degree).We supposed that operator exist on the four area and indicated location of critical organs(eyes, breast, gonad). The spatial doses were measured depending on distance( 80, 100, 120, and 140 cm) and location of critical organs. The spatial doses of area of 225 degree were 114.5 mR/h (eyes location), 143.1 mR/h (breast location) and 147 mR/h (gonad location) in 80 cm. When changed location of x-ray generator, spatial dose increased in 18.1±10.5%, averagely. We certified spatial dose in the operator locations, Using the results of this study, It is feasible to protect operator from radiation in neuro-interventional procedures.

  5. Measuring radiation dose to patients undergoing fluoroscopically-guided interventions

    Science.gov (United States)

    Lubis, L. E.; Badawy, M. K.

    2016-03-01

    The increasing prevalence and complexity of fluoroscopically guided interventions (FGI) raises concern regarding radiation dose to patients subjected to the procedure. Despite current evidence showing the risk to patients from the deterministic effects of radiation (e.g. skin burns), radiation induced injuries remain commonplace. This review aims to increase the awareness surrounding radiation dose measurement for patients undergoing FGI. A review of the literature was conducted alongside previous researches from the authors’ department. Studies pertaining to patient dose measurement, its formalism along with current advances and present challenges were reviewed. Current patient monitoring techniques (using available radiation dosimeters), as well as the inadequacy of accepting displayed dose as patient radiation dose is discussed. Furthermore, advances in real-time patient radiation dose estimation during FGI are considered. Patient dosimetry in FGI, particularly in real time, remains an ongoing challenge. The increasing occurrence and sophistication of these procedures calls for further advances in the field of patient radiation dose monitoring. Improved measuring techniques will aid clinicians in better predicting and managing radiation induced injury following FGI, thus improving patient care.

  6. Measurement of entrance skin dose and estimation of organ dose during pediatric chest radiography.

    Science.gov (United States)

    Kumaresan, M; Kumar, Rajesh; Biju, K; Choubey, Ajay; Kantharia, S

    2011-06-01

    Entrance skin dose (ESD) was measured to calculate the organ doses from the anteroposterior (AP) and posteroanterior (PA) chest x-ray projections for pediatric patients in an Indian hospital. High sensitivity tissue-equivalent thermoluminescent dosimeters (TLD, LiF: Mg, Cu, P chips) were used for measuring entrance skin dose. The respective organ doses were calculated using the Monte Carlo method (MCNP 3.1) to simulate the examination set-up and a three-dimensional mathematical phantom for representing an average 5-y-old Indian child. Using this method, conversion coefficients were derived for translating the measured ESD to organ doses. The average measured ESDs for the chest AP and PA projections were 0.305 mGy and 0.171 mGy, respectively. The average calculated organ doses in the AP and the PA projections were 0.196 and 0.086 mSv for the thyroid, 0.167 and 0.045 mSv for the trachea, 0.078 and 0.043 mSv for the lungs, 0.110 and 0.013 mSv for the liver, 0.002 and 0.016 mSv for the bone marrow, 0.024 and 0.002 mSv for the kidneys, and 0.109 and 0.023 mSv for the heart, respectively. The ESD and organ doses can be reduced significantly with the proper radiological technique. According to these results, the chest PA projection should be preferred over the AP projection in pediatric patients. The estimated organ doses for the chest AP and PA projections can be used for the estimation of the associated risk.

  7. Accurate skin dose measurements using radiochromic film in clinical applications.

    Science.gov (United States)

    Devic, S; Seuntjens, J; Abdel-Rahman, W; Evans, M; Olivares, M; Podgorsak, E B; Vuong, Té; Soares, Christopher G

    2006-04-01

    Megavoltage x-ray beams exhibit the well-known phenomena of dose buildup within the first few millimeters of the incident phantom surface, or the skin. Results of the surface dose measurements, however, depend vastly on the measurement technique employed. Our goal in this study was to determine a correction procedure in order to obtain an accurate skin dose estimate at the clinically relevant depth based on radiochromic film measurements. To illustrate this correction, we have used as a reference point a depth of 70 micron. We used the new GAFCHROMIC dosimetry films (HS, XR-T, and EBT) that have effective points of measurement at depths slightly larger than 70 micron. In addition to films, we also used an Attix parallel-plate chamber and a home-built extrapolation chamber to cover tissue-equivalent depths in the range from 4 micron to 1 mm of water-equivalent depth. Our measurements suggest that within the first millimeter of the skin region, the PDD for a 6 MV photon beam and field size of 10 x 10 cm2 increases from 14% to 43%. For the three GAFCHROMIC dosimetry film models, the 6 MV beam entrance skin dose measurement corrections due to their effective point of measurement are as follows: 15% for the EBT, 15% for the HS, and 16% for the XR-T model GAFCHROMIC films. The correction factors for the exit skin dose due to the build-down region are negligible. There is a small field size dependence for the entrance skin dose correction factor when using the EBT GAFCHROMIC film model. Finally, a procedure that uses EBT model GAFCHROMIC film for an accurate measurement of the skin dose in a parallel-opposed pair 6 MV photon beam arrangement is described.

  8. Usability of tartaric acid in dose measurements: an ESR study

    Science.gov (United States)

    Korkmaz, Güney; Polat, Mustafa; Korkmaz, Mustafa

    2010-03-01

    Unirradiated tartaric acid samples do not exhibit any ESR signal. However, the ESR spectra of irradiated samples contain many resonance signals. The dose-responce curves of the resonance signals, denoted as I 1, I 2, I 3 and I 4 in the present study, were found to increase linearly with the applied radiation dose in the range of 0.04-25 kGy. Adjusting the microvawe power and modulation amplitudes of 1.0 mW and 1.0 mT, respectively, was found to increase the sensitivity of tartaric acid. From the dose-response curves and room temperature decay data, it was concluded that the I 3 resonance signal of tartaric acid can be used for dose measurements at intermediate (0.04-0.4 kGy) and high dose (0.5-25 kGy) levels.

  9. Differential Electronic Nose in On-Line Dynamic Measurements

    Directory of Open Access Journals (Sweden)

    Osowski S.

    2014-12-01

    Full Text Available The paper presents application of differential electronic nose in the dynamic (on-line volatile measurement. First we compare the classical nose employing only one sensor array and its extension in the differential form containing two sensor arrays working in differential mode. We show that differential nose performs better at changing environmental conditions, especially the temperature, and well performs in the dynamic mode of operation. We show its application in recognition of different brands of tobacco

  10. Online measurement system for the surface inclination of metal workpieces

    Science.gov (United States)

    Yin, Peng; Sun, Changku; Wang, Peng; Yang, Qian

    2013-12-01

    The online measurement of the metal surfaces' parameters plays an important role in many industrial fields. Because the surfaces of the machined metal pieces have the characteristics of strong reflection and high possibilities of scattered disturbing irradiation points, this paper designs an online measurement system based on the measurement principles of linear structured light to detect whether the parameters of the machined metal surfaces' height difference and inclination fulfill the compliance requirements, in which the grayscale gravity algorithm is applied to extract the sub-pixel coordinates of the center of laser, the least squares method is employed to fit the data and the Pauta criterion is utilized to remove the spurious points. The repeat accuracy of this system has been tested. The experimental results prove that the precision of inclination is 0.046° RMS under the speed of 40mm/sec, and the precision of height difference is 0.072mm RMS, which meets the design expectations. Hence, this system can be applied to online industrial detection of high speed and high precision.

  11. Neutron dose and energy spectra measurements at Savannah River Plant

    Energy Technology Data Exchange (ETDEWEB)

    Brackenbush, L.W.; Soldat, K.L.; Haggard, D.L.; Faust, L.G.; Tomeraasen, P.L.

    1987-08-01

    Because some workers have a high potential for significant neutron exposure, the Savannah River Plant (SRP) contracted with Pacific Northwest Laboratory (PNL) to verify the accuracy of neutron dosimetry at the plant. Energy spectrum and neutron dose measurements were made at the SRP calibrations laboratory and at several other locations. The energy spectra measurements were made using multisphere or Bonner sphere spectrometers,/sup 3/He spectrometers, and NE-213 liquid scintillator spectrometers. Neutron dose equivalent determinations were made using these instruments and others specifically designed to determine dose equivalent, such as the tissue equivalent proportional counter (TEPC). Survey instruments, such as the Eberline PNR-4, and the thermoluminescent dosimeter (TLD)-albedo and track etch dosimeters (TEDs) were also used. The TEPC, subjectively judged to provide the most accurate estimation of true dose equivalent, was used as the reference for comparison with other devices. 29 refs., 43 figs., 13 tabs.

  12. The antiproton depth–dose curve measured with alanine detectors

    CERN Document Server

    Bassler, Niels; Palmans, Hugo; Holzscheiter, Michael H; Kovacevic, Sandra

    2008-01-01

    n this paper we report on the measurement of the antiproton depth–dose curve, with alanine detectors. The results are compared with simulations using the particle energy spectrum calculated by FLUKA, and using the track structure model of Hansen and Olsen for conversion of calculated dose into response. A good agreement is observed between the measured and calculated relative effectiveness although an underestimation of the measured values beyond the Bragg-peak remains unexplained. The model prediction of response of alanine towards heavy charged particles encourages future use of the alanine detectors for dosimetry of mixed radiation fields.

  13. Assessment of dose measurement uncertainty using RisøScan

    DEFF Research Database (Denmark)

    Helt-Hansen, J.; Miller, A.

    2006-01-01

    The dose measurement uncertainty of the dosimeter system RisoScan, office scanner and Riso B3 dosimeters has been assessed by comparison with spectrophotometer measurements of the same dosimeters. The reproducibility and the combined uncertainty were found to be approximately 2% and 4%, respectiv...

  14. Metacognitive planning: development and validation of an online measure.

    Science.gov (United States)

    Li, Jian; Zhang, Bo; Du, Han; Zhu, Ze; Li, Yi Ming

    2015-03-01

    Planning is the critical first stage of metacognition. Although it has long been emphasized theoretically, it has not been the subject of much empirical study due to the lack of a valid assessment tool. Because planning is a metacognitive process, online methods that collect data during task performance would much better capture it. The present study was conducted to develop an online measure of metacognitive planning. Researchers designed a puzzle task that took the form of the popular game Sokoban, and the ratio between planning time and total time of each item was chosen as the metacognitive planning index. The task was administered to a heterogeneous sample of 440 participants composed of college students as well as 5th-, 7th-, and 10th-grade students. The results showed that valid inference could be made from the time ratio score. Cronbach's alpha and test-retest correlation provided robust evidence of reliability of the time ratio score. Confirmatory factor analysis further confirmed its unidimensionality. Validity evidence also supported the use of the time ratio score. After controlling for demographic variables, intelligence, and motivation, the time ratio score still accounted for a significant proportion of variance of Sokoban performance, the Tower of London performance, and academic achievement. The time ratio score was also found to increase with age. Taken together, the results of the study revealed that the time ratio is a psychometrically sound online measure of metacognitive planning. 2015 APA, all rights reserved

  15. Student's music exposure: Full-day personal dose measurements

    Science.gov (United States)

    Washnik, Nilesh Jeevandas; Phillips, Susan L.; Teglas, Sandra

    2016-01-01

    Previous studies have shown that collegiate level music students are exposed to potentially hazardous sound levels. Compared to professional musicians, collegiate level music students typically do not perform as frequently, but they are exposed to intense sounds during practice and rehearsal sessions. The purpose of the study was to determine the full-day exposure dose including individual practice and ensemble rehearsals for collegiate student musicians. Sixty-seven college students of classical music were recruited representing 17 primary instruments. Of these students, 57 completed 2 days of noise dose measurements using Cirrus doseBadge programed according to the National Institute for Occupational Safety and Health criterion. Sound exposure was measured for 2 days from morning to evening, ranging from 7 to 9 h. Twenty-eight out of 57 (49%) student musicians exceeded a 100% daily noise dose on at least 1 day of the two measurement days. Eleven student musicians (19%) exceeded 100% daily noise dose on both days. Fourteen students exceeded 100% dose during large ensemble rehearsals and eight students exceeded 100% dose during individual practice sessions. Approximately, half of the student musicians exceeded 100% noise dose on a typical college schedule. This finding indicates that a large proportion of collegiate student musicians are at risk of developing noise-induced hearing loss due to hazardous sound levels. Considering the current finding, there is a need to conduct hearing conservation programs in all music schools, and to educate student musicians about the use and importance of hearing protection devices for their hearing. PMID:26960787

  16. Precise On-line Position Measurement for Particle Therapy

    CERN Document Server

    Actis, O; König, S

    2014-01-01

    An on-line beam position monitoring and regular beam stability tests are of utmost importance for the Quality Assurance (QA) of the patient treatment at any particle therapy facility. The Gantry${0.5 mm}2$ at the Paul Scherrer Institute uses a strip ionization chamber for the on-line beam position verification. The design of the strip chamber placed in the beam in front of the patient allows for a small beam penumbra in order to achieve a high-quality lateral beam delivery. The detector granularity and the low noise allow the reconstruction of the signals offered by Gantry${0.5 mm}2$ with a precision of about 0.1 mm. The frond-end electronics and the whole data processing sequence have been optimized for minimizing the dead time between the beam applications to about 2 ms: the charge collection is performed in about 1 ms, read-out takes place in 100 $\\mu$s while data verification and logging are completed in less than 1 ms. The sub-millimeter precision of the lateral reconstruction allows the dose inhomogenei...

  17. WE-D-BRA-04: Online 3D EPID-Based Dose Verification for Optimum Patient Safety

    Energy Technology Data Exchange (ETDEWEB)

    Spreeuw, H; Rozendaal, R; Olaciregui-Ruiz, I; Mans, A; Mijnheer, B; Herk, M van; Gonzalez, P [Netherlands Cancer Institute - Antoni van Leeuwenhoek, Amsterdam, Noord-Holland (Netherlands)

    2015-06-15

    Purpose: To develop an online 3D dose verification tool based on EPID transit dosimetry to ensure optimum patient safety in radiotherapy treatments. Methods: A new software package was developed which processes EPID portal images online using a back-projection algorithm for the 3D dose reconstruction. The package processes portal images faster than the acquisition rate of the portal imager (∼ 2.5 fps). After a portal image is acquired, the software seeks for “hot spots” in the reconstructed 3D dose distribution. A hot spot is in this study defined as a 4 cm{sup 3} cube where the average cumulative reconstructed dose exceeds the average total planned dose by at least 20% and 50 cGy. If a hot spot is detected, an alert is generated resulting in a linac halt. The software has been tested by irradiating an Alderson phantom after introducing various types of serious delivery errors. Results: In our first experiment the Alderson phantom was irradiated with two arcs from a 6 MV VMAT H&N treatment having a large leaf position error or a large monitor unit error. For both arcs and both errors the linac was halted before dose delivery was completed. When no error was introduced, the linac was not halted. The complete processing of a single portal frame, including hot spot detection, takes about 220 ms on a dual hexacore Intel Xeon 25 X5650 CPU at 2.66 GHz. Conclusion: A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for various kinds of gross delivery errors. The detection of hot spots was proven to be effective for the timely detection of these errors. Current work is focused on hot spot detection criteria for various treatment sites and the introduction of a clinical pilot program with online verification of hypo-fractionated (lung) treatments.

  18. Normal tissue dose conformality measures to guide radiotherapy fractionation decisions

    Energy Technology Data Exchange (ETDEWEB)

    Myerson, Robert J. [Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States)

    2011-04-15

    Purpose: To determine conditions under which hypofractionation could be favorable for a normal tissue--even if tumor [{alpha}/{beta}] exceeds the normal tissue's [{alpha}/{beta}]. Methods: The hypofractionation sufficiency condition (HSC) for an organ is defined as a dose conformality constraint such that, if satisfied, a family of tumor control probability isoeffective fractionation schemes will show decreasing normal tissue complication probability with decreasing number of fractions. Results: In the extended equivalent uniform dose (EUD) model [obtained by replacing dose with linear quadratic (LQ) 2 Gy equivalent dose], the HSC for a normal organ is proven to be satisfied if a suitably weighted average of the relative dose [hypofractionation sufficiency index (HSI)] is less than the ratio of normal tissue to tumor [{alpha}/{beta}]. The HSI is determined solely by dose distribution and the normal tissue volume factor, ''a.'' If the HSC is satisfied for every normal tissue of concern, then there is a therapeutic gain with hypofractionation. The corresponding multifractionation sufficiency condition (therapeutic gain with increasing number of fractions) and multifractionation sufficiency index (MSI) are also derived. A sample clinical case is presented. Conclusions: Within the context of the LQ/EUD models, conformality measures (HSI and MSI) can be used to inform fractionation decisions.

  19. Unit of measurement used and parent medication dosing errors.

    Science.gov (United States)

    Yin, H Shonna; Dreyer, Benard P; Ugboaja, Donna C; Sanchez, Dayana C; Paul, Ian M; Moreira, Hannah A; Rodriguez, Luis; Mendelsohn, Alan L

    2014-08-01

    Adopting the milliliter as the preferred unit of measurement has been suggested as a strategy to improve the clarity of medication instructions; teaspoon and tablespoon units may inadvertently endorse nonstandard kitchen spoon use. We examined the association between unit used and parent medication errors and whether nonstandard instruments mediate this relationship. Cross-sectional analysis of baseline data from a larger study of provider communication and medication errors. English- or Spanish-speaking parents (n = 287) whose children were prescribed liquid medications in 2 emergency departments were enrolled. Medication error defined as: error in knowledge of prescribed dose, error in observed dose measurement (compared to intended or prescribed dose); >20% deviation threshold for error. Multiple logistic regression performed adjusting for parent age, language, country, race/ethnicity, socioeconomic status, education, health literacy (Short Test of Functional Health Literacy in Adults); child age, chronic disease; site. Medication errors were common: 39.4% of parents made an error in measurement of the intended dose, 41.1% made an error in the prescribed dose. Furthermore, 16.7% used a nonstandard instrument. Compared with parents who used milliliter-only, parents who used teaspoon or tablespoon units had twice the odds of making an error with the intended (42.5% vs 27.6%, P = .02; adjusted odds ratio=2.3; 95% confidence interval, 1.2-4.4) and prescribed (45.1% vs 31.4%, P = .04; adjusted odds ratio=1.9; 95% confidence interval, 1.03-3.5) dose; associations greater for parents with low health literacy and non-English speakers. Nonstandard instrument use partially mediated teaspoon and tablespoon-associated measurement errors. Findings support a milliliter-only standard to reduce medication errors. Copyright © 2014 by the American Academy of Pediatrics.

  20. ionizing radiation measurements and assay of corresponding dose ...

    African Journals Online (AJOL)

    PUBLICATIONS1

    Measurements of ionizing radiation and corresponding dose rate around bottling and pharma- ceutical facilities in ... be monitored closely to protect the public from adverse health effects. Keywords: Gamma ... natural environment that we experience today. (Oke 2004 ... This decay is a phenomenon by which large number of ...

  1. PRECEDENTS FOR AUTHORIZATION OF CONTENTS USING DOSE RATE MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Abramczyk, G.; Bellamy, S.; Nathan, S.; Loftin, B.

    2012-06-05

    For the transportation of Radioactive Material (RAM) packages, the requirements for the maximum allowed dose rate at the package surface and in its vicinity are given in Title 10 of the Code of Federal Regulations, Section 71.47. The regulations are based on the acceptable dose rates to which the public, workers, and the environment may be exposed. As such, the regulations specify dose rates, rather than quantity of radioactive isotopes and require monitoring to confirm the requirements are met. 10CFR71.47 requires that each package of radioactive materials offered for transportation must be designed and prepared for shipment so that under conditions normally incident to transportation the radiation level does not exceed 2 mSv/h (200 mrem/h) at any point on the external Surface of the package, and the transport index does not exceed 10. Before shipment, the dose rate of the package is determined by measurement, ensuring that it conforms to the regulatory limits, regardless of any analyses. This is the requirement for all certified packagings. This paper discusses the requirements for establishing the dose rates when shipping RAM packages and the precedents for meeting these requirements by measurement.

  2. SEACAB qualification with Frascati Neutron Generator residual dose measurements

    Energy Technology Data Exchange (ETDEWEB)

    Töre, Candan, E-mail: c.tore@seaingenieria.es; Ortego, Pedro; Rodriguez, Alain

    2015-10-15

    Highlights: • We developed a new R2S residual dose methodology SEACAB for TBM shield design. • Combines MCNPX mesh tally and ACAB to compute activation in a fast and simple way. • We qualified SEACAB by comparison with second campaign of FNG “duct experiment”. • Calculated dose and flux compare very well with TUD measurements at 7 decay times. • Presently SEACAB is being used in the calculation of residual dose at ITER port 16. - Abstract: The European fusion technology programme considers two test blanket modules, both helium-cooled, one with lithium ceramic pebbles and beryllium and other with Pb–Li eutectic alloy. The high level of neutron flux required for tritium breeding and the neutron multiplication properties of Be and Pb imply the need for a large neutron attenuation in the associated shielding to meet the shutdown dose requirements. A new SEACAB methodology has been developed to apply the rigorous two-step method with the use of the mesh tally of MCNPX and activation code ACAB and it has been qualified with the results of the 2nd campaign of the “duct-experiment” performed with Frascati Neutron Generator in a block of steel and moderator layers with a central cavity where the residual photon flux and dose were measured.

  3. KERMA-based radiation dose management system for real-time patient dose measurement

    Science.gov (United States)

    Kim, Kyo-Tae; Heo, Ye-Ji; Oh, Kyung-Min; Nam, Sang-Hee; Kang, Sang-Sik; Park, Ji-Koon; Song, Yong-Keun; Park, Sung-Kwang

    2016-07-01

    Because systems that reduce radiation exposure during diagnostic procedures must be developed, significant time and financial resources have been invested in constructing radiation dose management systems. In the present study, the characteristics of an existing ionization-based system were compared to those of a system based on the kinetic energy released per unit mass (KERMA). Furthermore, the feasibility of using the KERMA-based system for patient radiation dose management was verified. The ionization-based system corrected the effects resulting from radiation parameter perturbations in general radiography whereas the KERMA-based system did not. Because of this difference, the KERMA-based radiation dose management system might overestimate the patient's radiation dose due to changes in the radiation conditions. Therefore, if a correction factor describing the correlation between the systems is applied to resolve this issue, then a radiation dose management system can be developed that will enable real-time measurement of the patient's radiation exposure and acquisition of diagnostic images.

  4. Assessment of patient dose in medical processes by in-vivo dose measuring devices: A review

    Science.gov (United States)

    Tuncel, Nina

    2016-11-01

    In-vivo dosimetry (IVD) in medicine especially in radiation therapy is a well-established and recommended procedure for the estimation of the dose delivered to a patient during the radiation treatment. It became even more important with the emerging use of new and more complex radiotherapy techniques such as intensity-modulated or image-guided radiation therapy. While IVD has been used in brachytherapy for decades and the initial motivation for performing was mainly to assess doses to organs at risk by direct measurements, it is now possible to calculate 3D for detection of deviations or errors. In-vivo dosimeters can be divided into real-time and passive detectors that need some finite time following irradiation for their analysis. They require a calibration against a calibrated ionization chamber in a known radiation field. Most of these detectors have a response that is energy and/or dose rate dependent and consequently require adjustments of the response to account for changes in the actual radiation conditions compared to the calibration situation. Correction factors are therefore necessary to take. Today, the most common dosimeters for patients' dose verification through in-vivo measurements are semiconductor diodes, thermo-luminescent dosimeters, optically stimulated luminescence dosimeters, metal-oxide-semiconductor field-effect transistors and plastic scintillator detectors with small outer diameters.

  5. Measurement of gold nanofilm dose enhancement using unlaminated radiochromic film

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, Joseph T., E-mail: rakowski@karmanos.org; Snyder, Michael G.; Hillman, Yair [Department of Radiation Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201 (United States); Laha, Suvra S.; Lawes, Gavin [Department of Physics, Wayne State University, Detroit, Michigan 48201 (United States); Buczek, Matthew G. [Department of Radiation Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201 and MidMichigan Health, Midland, Michigan 48670 (United States); Tucker, Mark A. [Department of Radiation Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201 and Missouri Cancer Associates, Columbia, Missouri 65202 (United States); Liu, Fangchao; Mao, Guangzhao [Department of Chemical Engineering and Materials Science, College of Engineering, Wayne State University, Detroit, Michigan 48201 (United States)

    2015-10-15

    Purpose: Bombarding high-Z material with x-ray radiation releases Auger electrons and Coster–Kronig electrons, along with deeper penetrating fluorescent x-rays and photoelectrons. The Auger and Coster–Kronig electron penetration distance is on the order of nanometers to micrometers in water or tissue, creating a large dose enhancement accompanied by a RBE greater than 1 at the cellular level. The authors’ aim is to measure the gold nanofilm dose enhancement factor (DEF) at the cellular level with unlaminated radiochromic film via primary 50 kVp tungsten x-ray spectrum interaction, similar to an electronic brachytherapy spectrum. Methods: Unlaminated Gafchromic{sup ®} EBT2 film and Monte Carlo modeling were combined to derive DEF models. Gold film of thickness 23.1 ±  4.3 nm and surface roughness of 1.2 ± 0.2 nm was placed in contact with unlaminated radiochromic film in a downstream orientation and exposed to a 50 kVp tungsten bremsstrahlung, mean energy 19.2 keV. Film response correction factors were derived by Monte Carlo modeling of electron energy deposition in the film’s active layer, and by measuring film energy dependence from 4.5 keV to 50 kVp. Results: The measured DEF within a 13.6 μm thick water layer was 0.29 with a mean dose of 94 ± 9.4 cGy from Au emissions and 324 ± 32.4 cGy from the 50 kVp primary beam. Monte Carlo derived correction factors allowed determination of Au contributed dose in shallower depths at 0.25 μm intervals. Maximum DEF of 18.31 was found in the first 0.25 μm water depth. Conclusions: Dose enhancement from Au nanofilm can be measured at the cellular level using unlaminated radiochromic film. Complementing the measured dose value with Monte Carlo calculations allows estimation of dose enhancement at depth increments within the cellular range.

  6. Simultaneous Objective Measurements Of Dose And Image Quality In Mammography

    Science.gov (United States)

    Pochon, Y.; Depeursinge, Ch.; Hessler, Ch.; Raimondi, S.; Valley, J.-F.

    1982-12-01

    The performance of a radiological system can be evaluated on the one hand by an objective determination of the quality of the produced image and, on the other hand, by the dose delivered to the patient. In order to measure these two factors in a single exposure a Kodak breast phantom has been modified so as to simulate the breast absorption. The dose distribution is measured with thermoluminescent detectors. By consideration of a theoretical model of the X-ray imaging in mammography, a single quality factor is computed from the contrast, the spatial resolution and the noise measured on the phantom image. We present results obtained in various working conditions, i.e. variable X-ray tube voltages, use of different screen-film combinations, use of a grid.

  7. 128 slice computed tomography dose profile measurement using thermoluminescent dosimeter

    Science.gov (United States)

    Salehhon, N.; Hashim, S.; Karim, M. K. A.; Ang, W. C.; Musa, Y.; Bahruddin, N. A.

    2017-05-01

    The increasing use of computed tomography (CT) in clinical practice marks the needs to understand the dose descriptor and dose profile. The purposes of the current study were to determine the CT dose index free-in-air (CTDIair) in 128 slice CT scanner and to evaluate the single scan dose profile (SSDP). Thermoluminescent dosimeters (TLD-100) were used to measure the dose profile of the scanner. There were three sets of CT protocols where the tube potential (kV) setting was manipulated for each protocol while the rest of parameters were kept constant. These protocols were based from routine CT abdominal examinations for male adult abdomen. It was found that the increase of kV settings made the values of CTDIair increased as well. When the kV setting was changed from 80 kV to 120 kV and from 120 kV to 140 kV, the CTDIair values were increased as much as 147.9% and 53.9% respectively. The highest kV setting (140 kV) led to the highest CTDIair value (13.585 mGy). The p-value of less than 0.05 indicated that the results were statistically different. The SSDP showed that when the kV settings were varied, the peak sharpness and height of Gaussian function profiles were affected. The full width at half maximum (FWHM) of dose profiles for all protocols were coincided with the nominal beam width set for the measurements. The findings of the study revealed much information on the characterization and performance of 128 slice CT scanner.

  8. Online dissolved methane and total dissolved sulfide measurement in sewers.

    Science.gov (United States)

    Liu, Yiwen; Sharma, Keshab R; Fluggen, Markus; O'Halloran, Kelly; Murthy, Sudhir; Yuan, Zhiguo

    2015-01-01

    Recent studies using short-term manual sampling of sewage followed by off-line laboratory gas chromatography (GC) measurement have shown that a substantial amount of dissolved methane is produced in sewer systems. However, only limited data has been acquired to date due to the low frequency and short span of this method, which cannot capture the dynamic variations of in-sewer dissolved methane concentrations. In this study, a newly developed online measuring device was used to monitor dissolved methane concentrations at the end of a rising main sewer network, over two periods of three weeks each, in summer and early winter, respectively. This device uses an online gas-phase methane sensor to measure methane under equilibrium conditions after being stripped from the sewage. The data are then converted to liquid-phase methane concentrations according to Henry's Law. The detection limit and range are suitable for sewer application and can be adjusted by varying the ratio of liquid-to-gas phase volume settings. The measurement presented good linearity (R² > 0.95) during field application, when compared to off-line measurements. The overall data set showed a wide variation in dissolved methane concentration of 5-15 mg/L in summer and 3.5-12 mg/L in winter, resulting in a significant average daily production of 24.6 and 19.0 kg-CH₄/d, respectively, from the network with a daily average sewage flow of 2840 m³/day. The dissolved methane concentration demonstrated a clear diurnal pattern coinciding with flow and sulfide fluctuation, implying a relationship with the wastewater hydraulic retention time (HRT). The total dissolved sulfide (TDS) concentration in sewers can be determined simultaneously with the same principle.

  9. Dose assessment in accordance with the measured position of size specific dose estimates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Su [Dept. of Radio-technology, Health Welfare, Wonkwang Health Science University, Iksan (Korea, Republic of); Hong, Sung Wan [Dept. of Radiology, Inje University Ilsan Paik Hospital, Iksan (Korea, Republic of); Kim, Jung Min [Dept. of Radiological Science, Korea University, Seoul (Korea, Republic of)

    2015-12-15

    This study investigated the size specific dose estimates of difference localizer on pediatric CT image. Seventy one cases of pediatric abdomen-pelvic CT (M:F=36:35) were included in this study. Anterior-posterior and lateral diameters were measured in axial CT images. Conversion factors from American Association of Physicists in Medicine (AAPM) report 204 were obtained for effective diameter to determine size specific dose estimate (SSDE) from the CT dose index volume (CTDIvol) recorded from the dose reports. For the localizer of mid-slice SSDE was 107.63% higher than CTDIvol and that of xiphoid-process slices SSDE was higher than 92.91%. The maximum error of iliac crest slices, xiphoid process slices and femur head slices between mid-slices were 7.48%, 17.81% and 14.04%. In conclusion, despite the SSDE of difference localizer has large number of errors, SSDE should be regarded as the primary evaluation tool of the patient radiation in pediatric CT for evaluation.

  10. Entrance surface dose measurements in mammography using thermoluminescence technique

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, T. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada Unidad Legaria del IPM Av. Legaria 694, 11500 Mexico D.F. (Mexico); Vega C, H.R.; Manzanares A, E [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Apdo. Postal 336, 98000 Zacatecas (Mexico); Azorin, J. [Universidad Autonoma Metropolitana-lztapalapa, Av. San Rafael Atlixco 186, 09340 Mexico D.F. (Mexico); Gonzalez, P.R. [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico Toluca, 52045 Salazar Estado de Mexico (Mexico)

    2007-07-01

    Full text: Of the various techniques that can be used for personnel dosimetry, thermoluminescence dosimetry (TLD) has emerged as a superior technique due to its manifold advantages over other methods of dose estimation. Various phosphors have been therefore investigated regarding their suitability for dosimetry. In this paper, a dosimetry system based on thermally stimulated luminescence (TSL) from zirconium oxide phosphors embedded in polytetrafluorethylene (ZrO{sub 2}+PTFE) was developed for entrance surface doses (ES) measurements in mammography. Small ZrO{sub 2} pellets of 5 mm in diameter and 0.8 mm in thickness were used. The reproducibility of measurements and linearity of ZrO{sub 2} were also studied. The results were compared with those obtained from LiF:Mg,Cu,P usually used for the determination of absorbed dose in mammography. Measurements both per unit air kerma and In vivo were performed using a mammography unit model DMR (General Electric). The results showed that ZrO{sub 2} TLDs can be used for the same X-ray dosimetry applications as LiF:Mg,Cu,P, with each type having the disadvantage of a response dependent on energy, particularly at low energies. These results indicate a considerable potential for use in routine control and In vivo ES measurements in mammography. (Author)

  11. Rasch Measurement of Collaborative Problem Solving in an Online Environment.

    Science.gov (United States)

    Harding, Susan-Marie E; Griffin, Patrick E

    2016-01-01

    This paper describes an approach to the assessment of human to human collaborative problem solving using a set of online interactive tasks completed by student dyads. Within the dyad, roles were nominated as either A or B and students selected their own roles. The question as to whether role selection affected individual student performance measures is addressed. Process stream data was captured from 3402 students in six countries who explored the problem space by clicking, dragging the mouse, moving the cursor and collaborating with their partner through a chat box window. Process stream data were explored to identify behavioural indicators that represented elements of a conceptual framework. These indicative behaviours were coded into a series of dichotomous items. These items represented actions and chats performed by students. The frequency of occurrence was used as a proxy measure of item difficulty. Then given a measure of item difficulty, student ability could be estimated using the difficulty estimates of the range of items demonstrated by the student. The Rasch simple logistic model was used to review the indicators to identify those that were consistent with the assumptions of the model and were invariant across national samples, language, curriculum and age of the student. The data were analysed using a one and two dimension, one parameter model. Rasch separation reliability, fit to the model, distribution of students and items on the underpinning construct, estimates for each country and the effect of role differences are reported. This study provides evidence that collaborative problem solving can be assessed in an online environment involving human to human interaction using behavioural indicators shown to have a consistent relationship between the estimate of student ability, and the probability of demonstrating the behaviour.

  12. Design of a tracking device for on-line dose monitoring in hadrontherapy

    Science.gov (United States)

    Battistoni, G.; Collamati, F.; De Lucia, E.; Faccini, R.; Marafini, M.; Mattei, I.; Muraro, S.; Paramatti, R.; Patera, V.; Pinci, D.; Rucinski, A.; Russomando, A.; Sarti, A.; Sciubba, A.; Solfaroli Camillocci, E.; Toppi, M.; Traini, G.; Voena, C.

    2017-02-01

    Hadrontherapy is a technique for cancer treatment that exploits ion beams (mostly protons and carbons). A critical issue is the accuracy that is achievable when monitoring the dose released by the beam to the tumor and to the surrounding tissues. We present the design of a tracking device, developed in the framework of the INSIDE project [1], capable of monitoring in real time the longitudinal profile of the dose delivered in the patient. This is possible by detecting the secondary particles produced by the interaction of the beam in the tissues. The position of the Bragg peak can be correlated to the charged particles emission point distribution measurement. The tracking device will be able to provide a fast response on the dose pattern by tracking the secondary charged fragments. The tracks are detected using 6 planes of scintillating fibers, providing the 3D coordinates of the track intersection with each plane. The fibers planes are followed by a plastic scintillator and by a small calorimeter built with a pixelated Lutetium Fine Silicate (LFS) crystal. A complete detector simulation, followed by the event reconstruction, has been performed to determine the achievable monitoring spatial resolution.

  13. Technology Development for Radiation Dose Measurement and Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bong Hwan; Chang, S. Y.; Lee, T. Y. (and others)

    2007-06-15

    The correction factors essential for the operation of In-Vivo counting system were produced and implemented into a field operation for the improvement of accuracy in measurement of the radioactivity inside a human body. The BiDAS2007 code which calculate an internal dose was developed by upgrading the former code prepared in the previous stage of this project. The method of using the multibioassy data, the maximum likelihood function and the Bayesian statistics were established to an internal dose based on the measurement data of radioactivity, intakes and retention of radioactivity in a human body and it can improve the accuracy in estimation of the intakes of radioactivity and the committed effective dose equivalent. In order to solve the problem of low detection efficiency of the conventional Bonner Sphere (BS) to a high energy neutron, the extended BS's were manufactured and the technique for neutron field spectrometry was established. The fast neutron and gamma spectrometry system with a BC501A scintillation detector was also prepared. Several neutron fluence spectra at several nuclear facilities were measured and collected by using the extended BS. The spectrum weighted responses of some neutron monitoring instruments were also derived by using these spectra and the detector response functions. A high efficient TL material for the neutron personal dosimeter was developed. It solved the main problem of low thermal stability and high residual dose of the commercial TLDs and has the sensitivity to neutron and to gamma radiation with 40 and 10 times higher respectively than them.

  14. The effect of on-line position correction on the dose distribution in focal radiotherapy for bladder cancer

    Directory of Open Access Journals (Sweden)

    Koning Caro CE

    2009-09-01

    Full Text Available Abstract Background The purpose of this study was to determine the dosimetric effect of on-line position correction for bladder tumor irradiation and to find methods to predict and handle this effect. Methods For 25 patients with unifocal bladder cancer intensity modulated radiotherapy (IMRT with 5 beams was planned. The requirement for each plan was that 99% of the target volume received 95% of the prescribed dose. Tumor displacements from -2.0 cm to 2.0 cm in each dimension were simulated, using 0.5 cm increments, resulting in 729 simulations per patient. We assumed that on-line correction for the tumor was applied perfectly. We determined the correlation between the change in D99% and the change in path length, which is defined here as the distance from the skin to the isocenter for each beam. In addition the margin needed to avoid underdosage was determined and the probability that an underdosage occurs in a real treatment was calculated. Results Adjustments for tumor displacement with perfect on-line position correction resulted in an altered dose distribution. The altered fraction dose to the target varied from 91.9% to 100.4% of the prescribed dose. The mean D99% (± SD was 95.8% ± 1.0%. There was a modest linear correlation between the difference in D99% and the change in path length of the beams after correction (R2 = 0.590. The median probability that a systematic underdosage occurs in a real treatment was 0.23% (range: 0 - 24.5%. A margin of 2 mm reduced that probability to Conclusion On-line position correction does result in an altered target coverage, due to changes in average path length after position correction. An extra margin can be added to prevent underdosage.

  15. Clinical application of a OneDose(TM) MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Kinhikar, Rajesh A [Department of Medical Physics, Tata Memorial Hospital, Parel, Mumbai 400 012 (India); Sharma, Pramod K [Department of Medical Physics, Tata Memorial Hospital, Parel, Mumbai 400 012 (India); Tambe, Chandrashekhar M [Department of Medical Physics, Tata Memorial Hospital, Parel, Mumbai 400 012 (India); Mahantshetty, Umesh M [Department of Radiation Oncology, Tata Memorial Hospital, Parel, Mumbai 400 012 (India); Sarin, Rajiv [Advanced Centre for Training Research and Education in Cancer, Kharghar, Navi Mumbai (India); Deshpande, Deepak D [Department of Medical Physics, Tata Memorial Hospital, Parel, Mumbai 400 012 (India); Shrivastava, Shyam K [Department of Radiation Oncology, Tata Memorial Hospital, Parel, Mumbai 400 012 (India)

    2006-07-21

    In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose(TM) in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs. (note)

  16. Factors for converting dose measured in polystyrene phantoms to dose reported in water phantoms for incident proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Moyers, M. F.; Vatnitsky, A. S.; Vatnitsky, S. M. [Loma Linda University Medical Center, Loma Linda, California 92354 (United States); Guthrie Clinic/Robert Packard Hospital, Sayre, Pennsylvania 18840 (United States); EBG MedAustron, Wiener Neustadt, Austria A2700 (Austria)

    2011-10-15

    Purpose: Previous dosimetry protocols allowed calibrations of proton beamline dose monitors to be performed in plastic phantoms. Nevertheless, dose determinations were referenced to absorbed dose-to-muscle or absorbed dose-to-water. The IAEA Code of Practice TRS 398 recommended that dose calibrations be performed with ionization chambers only in water phantoms because plastic-to-water dose conversion factors were not available with sufficient accuracy at the time of its writing. These factors are necessary, however, to evaluate the difference in doses delivered to patients if switching from calibration in plastic to a protocol that only allows calibration in water. Methods: This work measured polystyrene-to-water dose conversion factors for this purpose. Uncertainties in the results due to temperature, geometry, and chamber effects were minimized by using special experimental set-up procedures. The measurements were validated by Monte Carlo simulations. Results: At the peak of non-range-modulated beams, measured polystyrene-to-water factors ranged from 1.015 to 1.024 for beams with ranges from 36 to 315 mm. For beams with the same ranges and medium sized modulations, the factors ranged from 1.005 to 1.019. The measured results were used to generate tables of polystyrene-to-water dose conversion factors. Conclusions: The dose conversion factors can be used at clinical proton facilities to support beamline and patient specific dose per monitor unit calibrations performed in polystyrene phantoms.

  17. 3D measurement of absolute radiation dose in grid therapy

    Energy Technology Data Exchange (ETDEWEB)

    Trapp, J V [Joint Department of Physics, Institute of Cancer Research and Royal Marsden Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Department of Applied Physics, RMIT University, GPO Box 2476V, Melbourne 3001 (Australia); Warrington, A P [Joint Department of Physics, Institute of Cancer Research and Royal Marsden Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Partridge, M [Joint Department of Physics, Institute of Cancer Research and Royal Marsden Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Philps, A [Joint Department of Physics, Institute of Cancer Research and Royal Marsden Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Leach, M O [Cancer Research UK Clinical MR Research Group, Institute of Cancer Research and Royal Marsden Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Webb, S [Joint Department of Physics, Institute of Cancer Research and Royal Marsden Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom)

    2004-01-01

    Spatially fractionated radiotherapy through a grid is a concept which has a long history and was routinely used in orthovoltage radiation therapy in the middle of last century to minimize damage to the skin and subcutaneous tissue. With the advent of megavoltage radiotherapy and its skin sparing effects the use of grids in radiotherapy declined in the 1970s. However there has recently been a revival of the technique for use in palliative treatments with a single fraction of 10 to 20 Gy. In this work the absolute 3D dose distribution in a grid irradiation is measured for photons using a combination of film and gel dosimetry.

  18. Examining Online College Cyber Cheating Methods and Prevention Measures

    Science.gov (United States)

    Moten, James, Jr.; Fitterer, Alex; Brazier, Elise; Leonard, Jonathan; Brown, Avis

    2013-01-01

    Academic dishonesty in the online cheating environment of distance education learning has gained traction in the past decade. By a few simple keystrokes, students' can find a wide array of online services for hire to write research papers, complete homework assignments, or enroll on behalf of the student on record to take the entire online…

  19. Statistical Measures of Integrity in Online Testing: Empirical Study

    Science.gov (United States)

    Wielicki, Tom

    2016-01-01

    This paper reports on longitudinal study regarding integrity of testing in an online format as used by e-learning platforms. Specifically, this study explains whether online testing, which implies an open book format is compromising integrity of assessment by encouraging cheating among students. Statistical experiment designed for this study…

  20. An approach for online evaluations of dose consequences caused by small rotational setup errors in intracranial stereotactic radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lu Bo; Li, Jonathan; Kahler, Darren; Yan Guanghua; Mittauer, Kathryn; Shi Wenyin; Okunieff, Paul; Liu, Chihray [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32607 (United States)

    2011-11-15

    Purpose: The purpose of this work is to investigate the impact of small rotational errors on the magnitudes and distributions of spatial dose variations for intracranial stereotactic radiotherapy (SRT) treatment setups, and to assess the feasibility of using the original dose map overlaid with rotated contours (ODMORC) method as a fast, online evaluation tool to estimate dose changes (using DVHs) to clinical target volumes (CTVs) and organs-at-risks (OARs) caused by small rotational setup errors. Methods: Fifteen intracranial SRT cases treated with either three-dimensional conformal radiation therapy (3DCRT) or intensity-modulated radiation therapy (IMRT) techniques were chosen for the study. Selected cases have a variety of anatomical dimensions and pathologies. Angles of {+-}3 deg. and {+-}5 deg. in all directions were selected to simulate the rotational errors. Dose variations in different regions of the brain, CTVs, and OARs were evaluated to illustrate the various spatial effects of dose differences before and after rotations. DVHs accounting for rotations that were recomputed by the treatment planning system (TPS) and those generated by the ODMORC method were compared. A framework of a fast algorithm for multicontour rotation implemented by ODMORC is introduced as well. Results: The average values of relative dose variations between original dose and recomputed dose accounting for rotations were greater than 4.0% and 10.0% in absolute mean and in standard deviation, respectively, at the skull and adjacent regions for all cases. They were less than 1.0% and 2.5% in absolute mean and in standard deviation, respectively, for dose points 3 mm away from the skull. The results indicated that spatial dose to any part of the brain organs or tumors separated from the skull or head surface would be relatively stable before and after rotations. Statistical data of CTVs and OARs indicate the lens and cochleas have the large dose variations before and after rotations

  1. On-line MR imaging for dose validation of abdominal radiotherapy

    NARCIS (Netherlands)

    Glitzner, M; Crijns, S P M; de Senneville, B Denis; Kontaxis, C; Prins, F M; Lagendijk, J J W; Raaymakers, B W

    2015-01-01

    For quality assurance and adaptive radiotherapy, validation of the actual delivered dose is crucial.Intrafractional anatomy changes cannot be captured satisfactorily during treatment with hitherto available imaging modalitites. Consequently, dose calculations are based on the assumption of static an

  2. Online pretreatment verification of high-dose rate brachytherapy using an imaging panel

    Science.gov (United States)

    Fonseca, Gabriel P.; Podesta, Mark; Bellezzo, Murillo; Van den Bosch, Michiel R.; Lutgens, Ludy; Vanneste, Ben G. L.; Voncken, Robert; Van Limbergen, Evert J.; Reniers, Brigitte; Verhaegen, Frank

    2017-07-01

    Brachytherapy is employed to treat a wide variety of cancers. However, an accurate treatment verification method is currently not available. This study describes a pre-treatment verification system that uses an imaging panel (IP) to verify important aspects of the treatment plan. A detailed modelling of the IP was only possible with an extensive calibration performed using a robotic arm. Irradiations were performed with a high dose rate (HDR) 192Ir source within a water phantom. An empirical fit was applied to measure the distance between the source and the detector so 3D Cartesian coordinates of the dwell positions can be obtained using a single panel. The IP acquires 7.14 fps to verify the dwell times, dwell positions and air kerma strength (Sk). A gynecological applicator was used to create a treatment plan that was registered with a CT image of the water phantom used during the experiments for verification purposes. Errors (shifts, exchanged connections and wrong dwell times) were simulated to verify the proposed verification system. Cartesian source positions (panel measurement plane) have a standard deviation of about 0.02 cm. The measured distance between the source and the panel (z-coordinate) have a standard deviation up to 0.16 cm and maximum absolute error of  ≈0.6 cm if the signal is close to sensitive limit of the panel. The average response of the panel is very linear with Sk. Therefore, Sk measurements can be performed with relatively small errors. The measured dwell times show a maximum error of 0.2 s which is consistent with the acquisition rate of the panel. All simulated errors were clearly identified by the proposed system. The use of IPs is not common in brachytherapy, however, it provides considerable advantages. It was demonstrated that the IP can accurately measure Sk, dwell times and dwell positions.

  3. Online and offline video game use in adolescents: measurement invariance and problem severity.

    Science.gov (United States)

    Smohai, Máté; Urbán, Róbert; Griffiths, Mark D; Király, Orsolya; Mirnics, Zsuzsanna; Vargha, András; Demetrovics, Zsolt

    2017-01-01

    Despite the increasing popularity of video game playing, little is known about the similarities and differences between online and offline video game players. The aims of this study were (i) to test the applicability and the measurement invariance of the previously developed Problematic Online Gaming Questionnaire (POGQ) in both online and offline gamers and to (ii) examine the differences in these groups. Video game use habits and POGQ were assessed in a sample of 1,964 (71% male) adolescent videogame players. Those gamers who played at least sometimes in an online context were considered "online gamers," while those who played videogames exclusively offline were considered "offline gamers." Confirmatory factor analysis supported the measurement invariance across online and offline videogame players. According to the multiple indicators multiple causes (MIMIC) model, online gamers were more likely to score higher on overuse, interpersonal conflict, and social isolation subscales of the POGQ. The results of the present study suggest that online and offline gaming can be assessed using the same psychometric instrument. These findings open the possibility for future research studies concerning problematic video gaming to include participants who exclusively play online or offline games, or both. However, the study also identified important structural features about how online and offline gaming might contribute differently to problematic use. These results provide important information that could be utilized in parental education and the prevention program about the possible detrimental consequences of online vs. offline video gaming.

  4. Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

    CERN Document Server

    Leonard, Jessica Lynn

    2014-01-01

    The CMS beam and radiation monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be shown, including results from the January 201...

  5. Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

    CERN Document Server

    Leonard, Jessica Lynn; Hempel, Maria; Henschel, Hans; Karacheban, Olena; Lange, Wolfgang; Lohmann, Wolfgang; Novgorodova, Olga; Penno, Marek; Walsh, Roberval; Dabrowski, Anne; Guthoff, Moritz; Loos, R; Ryjov, Vladimir; Burtowy, Piotr; Lokhovitskiy, Arkady; Odell, Nathaniel; Przyborowski, Dominik; Stickland, David P; Zagozdzinska, Agnieszka

    2014-01-01

    The CMS beam condition monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be discussed, including results from the January 201...

  6. Online monitoring of Mezcal fermentation based on redox potential measurements.

    Science.gov (United States)

    Escalante-Minakata, P; Ibarra-Junquera, V; Rosu, H C; De León-Rodríguez, A; González-García, R

    2009-01-01

    We describe an algorithm for the continuous monitoring of the biomass and ethanol concentrations as well as the growth rate in the Mezcal fermentation process. The algorithm performs its task having available only the online measurements of the redox potential. The procedure combines an artificial neural network (ANN) that relates the redox potential to the ethanol and biomass concentrations with a nonlinear observer-based algorithm that uses the ANN biomass estimations to infer the growth rate of this fermentation process. The results show that the redox potential is a valuable indicator of the metabolic activity of the microorganisms during Mezcal fermentation. In addition, the estimated growth rate can be considered as a direct evidence of the presence of mixed culture growth in the process. Usually, mixtures of microorganisms could be intuitively clear in this kind of processes; however, the total biomass data do not provide definite evidence by themselves. In this paper, the detailed design of the software sensor as well as its experimental application is presented at the laboratory level.

  7. ESR measurements of background doses in teeth of Japanese residents

    Energy Technology Data Exchange (ETDEWEB)

    Toyoda, S., E-mail: toyoda@dap.ous.ac.jp [Department of Applied Physics, Okayama University of Science, Okayama (Japan); Kondo, A. [Department of Applied Physics, Okayama University of Science, Okayama (Japan); Zumadilov, K.; Hoshi, M. [Research Institute of Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Miyazawa, C. [Deparment of Dentistry, Ohu University, Fukushima (Japan); Ivannikov, A. [Medical Radiological Research Center, Obninsk (Russian Federation)

    2011-09-15

    The background doses for the teeth of Japanese residents were obtained by electron spin resonance (ESR) method. The doses obtained from 77 of 92 samples are less than 100 mGy while the doses of the other samples are high up to 250 mGy. The doses for buccal part of the teeth are higher than lingual part possibly due to contributions from dental X ray examination. A positive correlation was found between the ages of the donors and the obtained doses. The averaged annual ESR dose was calculated to be 0.87 mGy/y. These doses have to be considered in actual retrospective dosimetry studies for possible radiation accidents. The statistically significant critical level for Japanese residents would be about 200 mGy for individual doses and about 100 mGy for averaged group doses for {alpha} = 5% for those with ages older than 50.

  8. ``In vivo'' Dose Measurements in High-Dose-Rate Brachytherapy Treatments for Cervical Cancer: A Project Proposal

    Science.gov (United States)

    Mejía, C. A. Reynoso; Burgos, A. E. Buenfil; Trejo, C. Ruiz; García, A. Mota; Durán, E. Trejo; Ponce, M. Rodríguez; de Buen, I. Gamboa

    2010-12-01

    The aim of this thesis project is to compare doses calculated from the treatment planning system using computed tomography images, with those measured "in vivo" by using thermoluminescent dosimeters placed at different regions of the rectum and bladder of a patient during high-dose-rate intracavitary brachytherapy treatment of uterine cervical carcinoma. The experimental dosimeters characterisation and calibration have concluded and the protocol to carry out the "in vivo" measurements has been established. In this work, the calibration curves of two types of thermoluminescent dosimeters (rods and chips) are presented, and the proposed protocol to measure the "in vivo" dose is fully described.

  9. Application of combined TLD and CR-39 PNTD method for measurement of total dose and dose equivalent on ISS

    Energy Technology Data Exchange (ETDEWEB)

    Benton, E.R. [Eril Research, Inc., Stillwater, Oklahoma (United States); Deme, S.; Apathy, I. [KFKI Atomic Energy Research Institute, Budapest (Hungary)

    2006-07-01

    To date, no single passive detector has been found that measures dose equivalent from ionizing radiation exposure in low-Earth orbit. We have developed the I.S.S. Passive Dosimetry System (P.D.S.), utilizing a combination of TLD in the form of the self-contained Pille TLD system and stacks of CR-39 plastic nuclear track detector (P.N.T.D.) oriented in three mutually orthogonal directions, to measure total dose and dose equivalent aboard the International Space Station (I.S.S.). The Pille TLD system, consisting on an on board reader and a large number of Ca{sub 2}SO{sub 4}:Dy TLD cells, is used to measure absorbed dose. The Pille TLD cells are read out and annealed by the I.S.S. crew on orbit, such that dose information for any time period or condition, e.g. for E.V.A. or following a solar particle event, is immediately available. Near-tissue equivalent CR-39 P.N.T.D. provides Let spectrum, dose, and dose equivalent from charged particles of LET{sub {infinity}}H{sub 2}O {>=} 10 keV/{mu}m, including the secondaries produced in interactions with high-energy neutrons. Dose information from CR-39 P.N.T.D. is used to correct the absorbed dose component {>=} 10 keV/{mu}m measured in TLD to obtain total dose. Dose equivalent from CR-39 P.N.T.D. is combined with the dose component <10 keV/{mu}m measured in TLD to obtain total dose equivalent. Dose rates ranging from 165 to 250 {mu}Gy/day and dose equivalent rates ranging from 340 to 450 {mu}Sv/day were measured aboard I.S.S. during the Expedition 2 mission in 2001. Results from the P.D.S. are consistent with those from other passive detectors tested as part of the ground-based I.C.C.H.I.B.A.N. intercomparison of space radiation dosimeters. (authors)

  10. Estimation of Electron Dose Delivered by a 0.4 MeV Accelerator from Bremsstrahlung Dose Measurements

    DEFF Research Database (Denmark)

    Karadjov, A. G.; Hansen, Jørgen-Walther

    1980-01-01

    Determination of a 0.4 MeV electron dose from a bremsstrahlung dose measurement using a converter-detector system is considered. The detector used is a Frickle dosimeter, and the converters are aluminum, copper and lead foils. Optimal converter thickness is ascertained experimentally for each mat...

  11. Radiation dose measurements during kilovoltage-cone beam computed tomography imaging in radiotherapy

    Directory of Open Access Journals (Sweden)

    A Sathish Kumar

    2016-01-01

    Conclusion: Radiation dose to the eye, breast, and the surface of the pelvis have been arrived at during CBCT. The doses measured on patients agreed closely with those measured on humanoid phantom and with published values.

  12. Analytical evaluation of dose measurement of critical accident at SILENE (Contract research)

    CERN Document Server

    Nakamura, T; Tonoike, K

    2003-01-01

    Institute for Radioprotection and Nuclear Safety (IRSN) and the OECD Nuclear Energy Agency (NEA) jointly organized SILENE Accident Dosimetry Intercomparison Exercise to intercompare the dose measurement systems of participating countries. Each participating country carried out dose measurements in the same irradiation field, and the measurement results were mutually compared. The participated in the exercise to measure the doses of gamma rays and neutron from SILENE by using thermoluminescence dosimeters (TLD's) and an alanine dosimeter. In this examination, the derived evaluation formulae for obtaining a tissue-absorbed dose from measured value (ambient dose equivalent) of TLD for neutron. We reported the tissue-absorbed dose computed using this evaluation formula to OECD/NEA. TLD's for neutron were irradiated in the TRACY facility to verify the evaluation formulae. The results of TLD's were compared with the calculations of MCNP and measurements with alanine dose meter. We found that the ratio of the dose b...

  13. Low altitude dose measurements from APEX, CRRES and DMSP.

    Science.gov (United States)

    Mullen, E G; Gussenhoven, M S; Bell, J T; Madden, D; Holeman, E; Delorey, D

    1998-01-01

    Dosimeter data taken on the APEX (1994-1996), CRRES (1990-1991) and DMSP (1984-1987) satellites have been used to study the low altitude (down to 350 km) radiation environment. Of special concern has been the inner edge of the inner radiation belt due to its steep gradient. We have constructed dose models of the inner edge of the belt from all three spacecraft and put them into a personal computer utility, called APEXRAD, that calculates dose for user-selected orbits. The variation of dose for low altitude, circular orbits is given as a function of altitude, inclination and particle type. Dose-depth curves show that shielding greater than approximately 1/4 in Al is largely ineffectual for low altitude orbits. The contribution of outer zone electrons to low altitude dose is shown to be important only for thin shields and to have significant variation with magnetic activity and solar cycle.

  14. Dose rate measurement of a cobalt source 'Issledovatel' by means of Fricke dosimeter

    CERN Document Server

    Peimel-Stuglik, Z

    2001-01-01

    The results of measurements leading to the elaboration of a reliable and accurate dose rate determination for a cobalt irradiator 'Issledovatel' were presented. The dose measurements were done by means of classic Fricke dosimeter. The conclusions from measurements can be useful also for the dosimetry of other kinds of cobalt irradiators. The measurements were performed by a newly employed Laboratory for Measurements of Technological Doses staff and were a practical test of their proficiency in gamma ray dosimetry.

  15. Measuring quality, reputation and trust in online communities

    CERN Document Server

    Liao, Hao

    2012-01-01

    In the Internet era the information overload and the challenge to detect quality content has raised the issue of how to rank both resources and users in online communities. In this paper we develop a general ranking method that can simultaneously evaluate users' reputation and objects' quality in an iterative procedure, and that exploits the trust relationships and social acquaintances of users as an additional source of information. We test our method on two real online communities, the EconoPhysics forum and the Last.fm music catalogue, and determine how different variants of the algorithm influence the resultant ranking. We show the benefits of considering trust relationships, and define the form of the algorithm better apt to common situations.

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

    DEFF Research Database (Denmark)

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

    1977-01-01

    in polymeric solutions can be cast into flexible free-standing thin films of uniform thickness and reproducible response to ultraviolet and ionizing radiation. The increase in optical density versus energy deposited by radiation is linear over a wide range of doses and is for practical purposes independent...... of many polymeric systems in industrial radiation processing. The result is that errors due to energy dependence of response of the radiation sensor are effectively reduced, since the spectral sensitivity of the dose meter matches that of the polymer of interest, over a wide range of photon and electron...

  17. Radiation by the numbers: developing an on-line Canadian radiation dose calculator as a public engagement and education tool

    Energy Technology Data Exchange (ETDEWEB)

    Dalzell, M.T.J. [Sylvia Fedoruk Canadian Centre for Nuclear Innovation, Saskatoon, Saskatchewan (Canada)

    2016-06-15

    Concerns arising from misunderstandings about radiation are often cited as a main reason for public antipathy towards nuclear development and impede decision-making by governments and individuals. A lack of information about everyday sources of radiation exposure that is accessible, relatable and factual contributes to the problem. As part of its efforts to be a fact-based source of information on nuclear issues, the Sylvia Fedoruk Canadian Centre for Nuclear Innovation has developed an on-line Canadian Radiation Dose Calculator as a tool to provide context about common sources of radiation. This paper discusses the development of the calculator and describes how the Fedoruk Centre is using it and other tools to support public engagement on nuclear topics. (author)

  18. E-banking: Online Transactions and Security Measures

    Directory of Open Access Journals (Sweden)

    Hameed Ullah Khan

    2014-05-01

    Full Text Available This study presents the technology involved in the more important payment systems currently available to internet users. As the field is undergoing a major upheaval by changing the traditional banking services, e-commerce is facilitating change in recent years. These programs in-returns have shown lucrative growth in internet businesses and capital generation. Transactions on an international scale are the mark of highly demanding businesses with a global consumer base. Banks around the world provide their banking services online though electronic channels, one of the most widely used is the internet channel. Many people avail internet banking services which is convenient in this day and age. On-line banking platforms allow consumers to manage their accounts globally and at their convenience. The internet banking services have to be at top level of security and risk free in order to be trusted by customers. In this study the attack models have been explained and the top risks factors that the internet banking services come to face and applications have been discussed. This study deals with experimental models that can be applied to curb cybercrime attacks and make the internet banking applications more secure to the consumer strata.

  19. Global real-time dose measurements using the Automated Radiation Measurements for Aerospace Safety (ARMAS) system

    Science.gov (United States)

    Tobiska, W. Kent; Bouwer, D.; Smart, D.; Shea, M.; Bailey, J.; Didkovsky, L.; Judge, K.; Garrett, H.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R.; Bell, D.; Mertens, C.; Xu, X.; Wiltberger, M.; Wiley, S.; Teets, E.; Jones, B.; Hong, S.; Yoon, K.

    2016-11-01

    The Automated Radiation Measurements for Aerospace Safety (ARMAS) program has successfully deployed a fleet of six instruments measuring the ambient radiation environment at commercial aircraft altitudes. ARMAS transmits real-time data to the ground and provides quality, tissue-relevant ambient dose equivalent rates with 5 min latency for dose rates on 213 flights up to 17.3 km (56,700 ft). We show five cases from different aircraft; the source particles are dominated by galactic cosmic rays but include particle fluxes for minor radiation periods and geomagnetically disturbed conditions. The measurements from 2013 to 2016 do not cover a period of time to quantify galactic cosmic rays' dependence on solar cycle variation and their effect on aviation radiation. However, we report on small radiation "clouds" in specific magnetic latitude regions and note that active geomagnetic, variable space weather conditions may sufficiently modify the magnetospheric magnetic field that can enhance the radiation environment, particularly at high altitudes and middle to high latitudes. When there is no significant space weather, high-latitude flights produce a dose rate analogous to a chest X-ray every 12.5 h, every 25 h for midlatitudes, and every 100 h for equatorial latitudes at typical commercial flight altitudes of 37,000 ft ( 11 km). The dose rate doubles every 2 km altitude increase, suggesting a radiation event management strategy for pilots or air traffic control; i.e., where event-driven radiation regions can be identified, they can be treated like volcanic ash clouds to achieve radiation safety goals with slightly lower flight altitudes or more equatorial flight paths.

  20. Validation of SEACAB Methodology with Frascati (FNG) Photon Dose Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tore, C.; Ortego, P.; Rodriguez Rivada, A.

    2014-07-01

    In the operation of the International Thermonuclear Experimental Reactor (ITER) the correct estimation of the gamma dose rate produced from the structural materials after shut down is one of the important safety parameter for hands-on maintenance. SEACAB, a rigorous 2-step (R2S) computational method has been developed for the calculation of residual dose in 3-D geometry with the use of the MCNP5 and of the ACAB (ACtivation ABacus) inventory code. The method is very efficient in hardware requirements being essentially modular. Starting from a single MCNP5 run permits a progressive improvement in the spatial detail of the material layers for the activation calculation and obtains separated source distributions for the isotopes contributing to the photon dose. (Author)

  1. Organ dose measurement using Optically Stimulated Luminescence Detector (OSLD) during CT examination

    Science.gov (United States)

    Yusuf, Muhammad; Alothmany, Nazeeh; Abdulrahman Kinsara, Abdulraheem

    2017-10-01

    This study provides detailed information regarding the imaging doses to patient radiosensitive organs from a kilovoltage computed tomography (CT) scan procedure using OSLD. The study reports discrepancies between the measured dose and the calculated dose from the ImPACT scan, as well as a comparison with the dose from a chest X-ray radiography procedure. OSLDs were inserted in several organs, including the brain, eyes, thyroid, lung, heart, spinal cord, breast, spleen, stomach, liver and ovaries, of the RANDO phantom. Standard clinical scanning protocols were used for each individual site, including the brain, thyroid, lung, breast, stomach, liver and ovaries. The measured absorbed doses were then compared with the simulated dose obtained from the ImPACT scan. Additionally, the equivalent doses for each organ were calculated and compared with the dose from a chest X-ray radiography procedure. Absorbed organ doses measured by OSLD in the RANDO phantom of up to 17 mGy depend on the organ scanned and the scanning protocols used. A maximum 9.82% difference was observed between the target organ dose measured by OSLD and the results from the ImPACT scan. The maximum equivalent organ dose measured during this experiment was equal to 99.899 times the equivalent dose from a chest X-ray radiography procedure. The discrepancies between the measured dose with the OSLD and the calculated dose from the ImPACT scan were within 10%. This report recommends the use of OSLD for measuring the absorbed organ dose during CT examination.

  2. Paediatric dose measurement in a full-body digital radiography unit

    Energy Technology Data Exchange (ETDEWEB)

    Maree, Gert J.; Hering, Egbert R. [Groote Schuur Hospital and University of Cape Town, Division of Medical Physics, Cape Town (South Africa); Irving, Benjamin J. [University of Cape Town, MRC/UCT Medical Imaging Research Unit, Department of Human Biology, Cape Town, Western Cape (South Africa)

    2007-10-15

    Ionizing radiation has a detrimental effect on the human body, particularly in children. Thus it is important to minimize the dose. Linear slit-scanning X-ray units offer the possibility of dose reductions. In order to further develop linear slit-scanning radiography, the dose needs to be accurately calculated for various examinations. To measure the entrance dose (free-in-air) and calculate the effective doses for various radiological examinations in children on Lodox Statscan and Shimadzu radiography units. Entrance doses (free-in-air) were measured using a dose meter and ionization chamber on the Statscan and Shimadzu units at two South African hospitals. The entrance doses were measured for a number of common examinations and were used to compute the effective dose using a Monte Carlo program. The standard deviation of the entrance doses was in the range 0-0.6%. The effective dose from the Statscan unit was well below that from the Shimadzu unit as well as that found in other radiological studies from around the world in children. The one exception was chest examination where the dose was similar to that in other studies worldwide due to the use of Chest AP projection compared to Chest PA used in the comparitive studies. Linear slit-scanning systems help reduce the dose in radiological examinations in children. (orig.)

  3. Measuring dose from radiotherapy treatments in the vicinity of a cardiac pacemaker.

    Science.gov (United States)

    Peet, Samuel C; Wilks, Rachael; Kairn, Tanya; Crowe, Scott B

    2016-12-01

    This study investigated the dose absorbed by tissues surrounding artificial cardiac pacemakers during external beam radiotherapy procedures. The usefulness of out-of-field reference data, treatment planning systems, and skin dose measurements to estimate the dose in the vicinity of a pacemaker was also examined. Measurements were performed by installing a pacemaker onto an anthropomorphic phantom, and using radiochromic film and optically stimulated luminescence dosimeters to measure the dose in the vicinity of the device during the delivery of square fields and clinical treatment plans. It was found that the dose delivered in the vicinity of the cardiac device was unevenly distributed both laterally and anteroposteriorly. As the device was moved distally from the square field, the dose dropped exponentially, in line with out-of-field reference data in the literature. Treatment planning systems were found to substantially underestimate the dose for volumetric modulated arc therapy, helical tomotherapy, and 3D conformal treatments. The skin dose was observed to be either greater or lesser than the dose received at the depth of the device, depending on the treatment site, and so care should be if skin dose measurements are to be used to estimate the dose to a pacemaker. Square field reference data may be used as an upper estimate of absorbed dose per monitor unit in the vicinity of a cardiac device for complex treatments involving multiple gantry angles. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. Measurement of the dose in quartz in the presence of feldspar contamination

    DEFF Research Database (Denmark)

    Wallinga, J.; Murray, A.S.; Bøtter-Jensen, L.

    2002-01-01

    , without seriously affecting the quartz OSL signal. A single-aliquot regenerative-dose protocol is proposed which, in our samples, allows accurate measurement of the dose in quartz in the presence of feldspar contamination. The protocol also has potential use for quartz dose determination in mixed...

  5. Measurement of effective dose for paediatric scoliotic patients

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chih-I. [School of Medical Radiation Sciences, University of Sydney, Lidcombe NSW 1825 (Australia); McLean, Donald [School of Medical Radiation Sciences, University of Sydney, Lidcombe NSW 1825 (Australia)]. E-mail: rdmc@imag.wsahs.nsw.gov.au; Robinson, John [School of Medical Radiation Sciences, University of Sydney, Lidcombe NSW 1825 (Australia)

    2005-05-01

    Purpose: Paediatric radiation dose from scoliosis X-ray examinations is of concern because of its routine nature. Few studies have calculated effective dose which is the primary indicator of radiation risk. This study reports on the use of a new flexible Monte Carlo software package PCXMC14 for such calculation from documented radiographic and patient data. Method: Patient and radiographic data were collected from 54 patient examinations for both postero-anterior (PA) and lateral X-ray projections. A spreadsheet mainly based on radiographic calibration was used to process the raw data and compute entrance air kerma for input in the PCXMC program. A partitioning model was developed to more accurately estimate the effect of an aluminium wedge filter. Results: Results showed the effective dose ranged from 81 to 123 {mu}Sv for the PA projection and 124 to 207 {mu}Sv for the lateral projection, with patient weights varying from 20 to 70 kg. Conclusions: This study demonstrates the usefulness of the PCXMC program to evaluate the effective dose in paediatric scoliosis radiography.

  6. Combined scintillation detector for gamma dose rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Viererbl, L.; Novakova, O.; Jursova, L. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky)

    1990-01-01

    The specifications are described of a newly developed scintillation detector, essentially consisting of a plastic scintillator completed with inorganic scintillators ZnS(Ag) and NaI(Tl). The gamma dose rate is derived from the photomultiplier anode current. The composition and sizes of the scintillators and the capsule are selected so as to minimise the energy dependence errors and directional dependence errors of the detector response over a wide range of energies and/or angles. (author).

  7. Volumetric measurement of pulmonary nodules at low-dose chest CT : effect of reconstruction setting on measurement variability

    NARCIS (Netherlands)

    Wang, Y.; de Bock, G.H.; van Klaveren, R.J.; van Ooyen, P.; Tukker, W.; Zhao, Y.; Dorrius, M.D.; Proenca, R.V.; Post, W.J.; Oudkerk, M.

    2010-01-01

    To assess volumetric measurement variability in pulmonary nodules detected at low-dose chest CT with three reconstruction settings. The volume of 200 solid pulmonary nodules was measured three times using commercially available semi-automated software of low-dose chest CT data-sets reconstructed wit

  8. SU-E-T-196: Comparative Analysis of Surface Dose Measurements Using MOSFET Detector and Dose Predicted by Eclipse - AAA with Varying Dose Calculation Grid Size

    Energy Technology Data Exchange (ETDEWEB)

    Badkul, R; Nejaiman, S; Pokhrel, D; Jiang, H; Kumar, P [University of Kansas Medical Center, Kansas City, KS (United States)

    2015-06-15

    Purpose: Skin dose can be the limiting factor and fairly common reason to interrupt the treatment, especially for treating head-and-neck with Intensity-modulated-radiation-therapy(IMRT) or Volumetrically-modulated - arc-therapy (VMAT) and breast with tangentially-directed-beams. Aim of this study was to investigate accuracy of near-surface dose predicted by Eclipse treatment-planning-system (TPS) using Anisotropic-Analytic Algorithm (AAA)with varying calculation grid-size and comparing with metal-oxide-semiconductor-field-effect-transistors(MOSFETs)measurements for a range of clinical-conditions (open-field,dynamic-wedge, physical-wedge, IMRT,VMAT). Methods: QUASAR™-Body-Phantom was used in this study with oval curved-surfaces to mimic breast, chest wall and head-and-neck sites.A CT-scan was obtained with five radio-opaque markers(ROM) placed on the surface of phantom to mimic the range of incident angles for measurements and dose prediction using 2mm slice thickness.At each ROM, small structure(1mmx2mm) were contoured to obtain mean-doses from TPS.Calculations were performed for open-field,dynamic-wedge,physical-wedge,IMRT and VMAT using Varian-21EX,6&15MV photons using twogrid-sizes:2.5mm and 1mm.Calibration checks were performed to ensure that MOSFETs response were within ±5%.Surface-doses were measured at five locations and compared with TPS calculations. Results: For 6MV: 2.5mm grid-size,mean calculated doses(MCD)were higher by 10%(±7.6),10%(±7.6),20%(±8.5),40%(±7.5),30%(±6.9) and for 1mm grid-size MCD were higher by 0%(±5.7),0%(±4.2),0%(±5.5),1.2%(±5.0),1.1% (±7.8) for open-field,dynamic-wedge,physical-wedge,IMRT,VMAT respectively.For 15MV: 2.5mm grid-size,MCD were higher by 30%(±14.6),30%(±14.6),30%(±14.0),40%(±11.0),30%(±3.5)and for 1mm grid-size MCD were higher by 10% (±10.6), 10%(±9.8),10%(±8.0),30%(±7.8),10%(±3.8) for open-field, dynamic-wedge, physical-wedge, IMRT, VMAT respectively.For 6MV, 86% and 56% of all measured values

  9. Organ dose conversions from ESR measurements using tooth enamel of atomic bomb survivors.

    Science.gov (United States)

    Takahashi, Fumiaki; Sato, Kaoru

    2012-03-01

    Dose conversions were studied for dosimetry of atomic bomb survivors based upon electron spin resonance (ESR) measurements of tooth enamel. Previously analysed data had clarified that the tooth enamel dose could be much larger than other organ doses from a low-energy photon exposure. The radiation doses to other organs or whole-body doses, however, are assumed to be near the tooth enamel dose for photon energies which are dominant in the leakage spectrum of the Hiroshima atomic bomb assumed in DS02. In addition, the thyroid can be a candidate for a surrogate organ in cases where the tooth enamel dose is not available in organ dosimetry. This paper also suggests the application of new Japanese voxel phantoms to derive tooth enamel doses by numerical analyses.

  10. Measuring radon concentrations and estimating dose in tourist caves.

    Science.gov (United States)

    Martín Sánchez, A; de la Torre Pérez, J; Ruano Sánchez, A B; Naranjo Correa, F L

    2015-11-01

    Caves and mines are considered to be places of especial risk of exposure to (222)Rn. This is particularly important for guides and workers, but also for visitors. In the Extremadura region (Spain), there are two cave systems in which there are workers carrying out their normal everyday tasks. In one, visits have been reduced to maintain the conditions of temperature and humidity. The other comprises several caves frequently visited by school groups. The caves were radiologically characterised in order to estimate the dose received by workers or possible hazards for visitors.

  11. Estimation of the fetal dose by dose measurement during an irradiation of a parotid tumor; Estimation de la dose foetale par mesure de dose lors d'une irradiation d'une tumeur de la parotide

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, V.; Graff-Cailleaud, P.; Peiffert, D. [Centre Alexis-Vautrin, 54 - Vandoeuvre-les-Nancy (France); Noel, A. [Institut National Polytechnique de Lorraine, CRAN CNRS UMR-7039, 54 - Vandoeuvre-les-Nancy (France)

    2006-11-15

    The irradiation of a five months pregnant patient has been made for a right parotid attack. In conformation with the legislative texts relative to radiation protection ( publication 84 of the ICRP) an estimation of the dose received for the fetus has been led by dose measurement on phantom. With the dose limit ( 100 mGy) recommended in the publication 84 of the ICRP neither modification of the treatment nor abortion was necessary. (N.C.)

  12. Online junction temperature measurement using peak gate current

    DEFF Research Database (Denmark)

    Baker, Nick; Munk-Nielsen, Stig; Iannuzzo, Francesco

    2015-01-01

    A new method for junction temperature measurement of MOS-gated power semiconductor switches is presented. The measurement method involves detecting the peak voltage over the external gate resistor of an IGBT or MOSFET during turn-on. This voltage is directly proportional to the peak gate current...

  13. CALUX measurements: statistical inferences for the dose-response curve.

    Science.gov (United States)

    Elskens, M; Baston, D S; Stumpf, C; Haedrich, J; Keupers, I; Croes, K; Denison, M S; Baeyens, W; Goeyens, L

    2011-09-30

    Chemical Activated LUciferase gene eXpression [CALUX] is a reporter gene mammalian cell bioassay used for detection and semi-quantitative analyses of dioxin-like compounds. CALUX dose-response curves for 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD] are typically smooth and sigmoidal when the dose is portrayed on a logarithmic scale. Non-linear regression models are used to calibrate the CALUX response versus TCDD standards and to convert the sample response into Bioanalytical EQuivalents (BEQs). Several complications may arise in terms of statistical inference, specifically and most important is the uncertainty assessment of the predicted BEQ. This paper presents the use of linear calibration functions based on Box-Cox transformations to overcome the issue of uncertainty assessment. Main issues being addressed are (i) confidence and prediction intervals for the CALUX response, (ii) confidence and prediction intervals for the predicted BEQ-value, and (iii) detection/estimation capabilities for the sigmoid and linearized models. Statistical comparisons between different calculation methods involving inverse prediction, effective concentration ratios (ECR(20-50-80)) and slope ratio were achieved with example datasets in order to provide guidance for optimizing BEQ determinations and expand assay performance with the recombinant mouse hepatoma CALUX cell line H1L6.1c3.

  14. Comparative skin dose measurement in the treatment of anal canal cancer: conventional versus conformal therapy.

    Science.gov (United States)

    Devic, Slobodan; Hegyi, Gyorgy; Vuong, Té; Muanza, Thierry; Podgorsak, Ervin B

    2004-06-01

    The subject of this work was to compare the effect of Conventional and Conformal techniques, used for anal canal cancer treatments, on the skin dose deposition. Skin dose was measured on a Rando phantom using XR-T GAFCHROMIC film. A skin surface dose histogram was constructed and a skin dose profile in the sagittal direction of the perineal region was measured, for both techniques. The measured skin dose in the anterior and posterior region of the skin exposed to radiation is from two to ten times higher when using a conventional technique. In the perineal region, an 85% of the prescription isodose line spreads over 25% of the perineum for conformal technique as compared to 65% with conventional techniques. In addition, conformal technique dose profiles confine better the anatomical position of the anal verge than conventional techniques. Results presented in this work confirm clinically observed improvement in the radiation-induced dermatitis when using the conformal technique.

  15. Experimental measurement of radiation dose in a dedicated breast CT system

    CERN Document Server

    Shan-Wei, Shen; Hang, Shu; Xiao, Tang; Cun-Feng, Wei; Yu-Shou, Song; Rong-Jian, Shi; Long, Wei

    2013-01-01

    Radiation dose is an important performance indicator of a dedicated breast CT (DBCT). In this paper, the method of putting thermoluminescent dosimeters (TLD) into a breast shaped PMMA phantom to study the dose distribution in breasts was improved by using smaller TLDs and a new half-ellipsoid PMMA phantom. Then the weighted CT dose index (CTDIw) was introduced to average glandular assessment in DBCT for the first time and two measurement modes were proposed for different sizes of breasts. The dose deviations caused by using cylindrical phantoms were simulated using the Monte Carlo method and a set of correction factors were calculated. The results of the confirmatory measurement with a cylindrical phantom (11cm/8cm) show that CTDIw gives a relatively conservative overestimate of the average glandular dose comparing to the results of Monte Carlo simulation and TLDs measurement. But with better practicability and stability, the CTDIw is suitable for dose evaluations in daily clinical practice. Both of the TLDs ...

  16. Online measurement of contents in compound fertilizer and application research using VIS-NIR spectroscopy

    Science.gov (United States)

    Lin, Zhidan; Wang, Yubing; Wang, Rujing; Liu, Jing; Lu, Cuiping; Wang, Liusan

    2015-10-01

    The on-line measurement of the main component contents is essential for production, detection and identification of compound fertilizer. Using developed VIS-NIR sensors for on-line measurement of the main component contents in compound fertilizer, primary results about nitrogen (N), phosphorus pentoxide (P2O5) and potassium oxide (K2O) were reported. A visible (VIS) and near infrared (NIR) spectrophotometer (Ocean Optics), with a measurement range of 360.18-2221.53 nm was used to measure fertilizer spectra in reflectance mode. By using principal component analysis (PCA) and mahalanobis distance method, 3 outlier samples were detected and eliminated from 174 samples firstly. Then these models of three components with the 124 samples in calibration set were established using principal component regress (PCR) and partial least squares regression (PLS) coupled respectively with the full cross-validation technique after preprocessing the original spectrum with different methods. These models were used to estimate the contents of N, P2O5 and K2O of the other 47 samples in predicted set. The research results showed that the method could be applied to rapid measurement to the main component contents in compound fertilizer. Compared with the traditional analysis method, the on-line measurement could do it rapidly, inexpensively and pollution-freely. It suggested the potential use of the VIS-NIR sensing system for on-line measurement in the production, detection and identification process of compound fertilizer.

  17. Clinical application of glass dosimeter for in vivo dose measurements of total body irradiation treatment technique

    Energy Technology Data Exchange (ETDEWEB)

    Rah, Jeong-Eun; Hwang, Ui-Jung; Jeong, Hojin; Lee, Sang-Yeob; Lee, Doo-Hyun; Shin, Dong Ho; Yoon, Myonggeun; Lee, Se Byeong [Proton Therapy Center, National Cancer Center, 809 Madu-dong, Ilsan-gu, Goyang-si, Gyeonggi-do, 410-769 (Korea, Republic of); Lee, Rena [Department of Radiation Oncology, Mokdong Hospital, Ewha Womans University College of Medicine (Korea, Republic of); Park, Sung Yong, E-mail: cool_park@ncc.re.k [Proton Therapy Center, National Cancer Center, 809 Madu-dong, Ilsan-gu, Goyang-si, Gyeonggi-do, 410-769 (Korea, Republic of)

    2011-01-15

    The commercially available glass dosimeter (model GD-301) was investigated for its dosimetric characteristics, in order to evaluate its use for in vivo dosimetry. We specifically assessed overall precision of dosimetric dose data in patients who received treatment with the total body irradiation (TBI). Uniformity obtained in this study was within 1.2% (1 SD). The dose-response was linear in the range of 0.5-10 Gy with R of 0.999. Dose rate, SSD, field size, angular and energy dependence were found to be within 3.0%. In vivo skin dosimetry for TBI was performed for 3 patients. For all patients, the glass dosimeter was exposed and measured dose recorded for one fraction in addition to conventional used TLD and MOSFET. Overall uncertainty of the glass dosimeter for in vivo dose measurement was estimated at 2.4% (68.3% confidence level). The measured doses of the glass dosimeter were well within {+-}5.0% of the prescription dose at all sites expect mediastinum of one patient, for which it is within {+-}5.7%. Agreement of measured doses between glass dosimeter and TLD, MOSFET was within {+-}6.3% and {+-}6.6%, respectively. Results show that the glass dosimeter can be used as an accurate and reproducible dosimeter for TBI treatment skin dose measurements. The glass dosimeter is a practical alternative to TLD or MOSFET as an in vivo dosimeter.

  18. Measurements of the dose delivered during CT exams using AAPM Task Group Report No. 111.

    Science.gov (United States)

    Descamps, Caroline; Gonzalez, Mercedes; Garrigo, Edgardo; Germanier, Alejandro; Venencia, Daniel

    2012-11-08

    The computed tomography dose index (CTDI) measured with a 10 cm long pencil ionization chamber placed in a 14 cm long PMMA phantom is typically used to evaluate the doses delivered during CT procedure. For the new generation of CT scanners, the efficiency of this methodology is low because it excludes the contribution of radiation scattered beyond the 100 mm range of integration along z. The AAPM TG111 Report proposes a new measurement modality using a small volume ionization chamber positioned in a phantom long enough to establish dose equilibrium at the location of the chamber. In this work, the AAPM report was implemented. The minimum scanning length needed to obtain cumulative dose equilibrium was evaluated. The equilibrium dose was determined and compared to CTDI values informed by the CT scanner, and the dose values were confirmed with TLD measurements. The difference between doses measured with TLD and with the ionization chamber (IC) was below 1% and the repeatability of the measurements' setup was 0.4%. The measurements showed that the scanning lengths needed to reach the cumulated dose equilibrium were 450 mm and 380 mm for the central and peripheral axes, respectively, which justifies the phantom length. For the studied clinical protocols, the doses measured were about 30% higher than those informed by the CT scanner. For the new generation of CT systems with wider longitudinal detector size or cone-beam technology, the current CTDI measurements may no longer be adequate, and the informed CTDI tends to undervalue the dose delivered. It is therefore important to evaluate CT radiation doses following the AAPM TG111 methodology.

  19. Dose measurement for systemic irradiation with a moving table specially designed for total body irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Makoto; Oida, Masatada; Nagumo, Junya; Fujita, Katsuhisa; Furuya, Teruo; Watanabe, Yoshiharu [Hokkaido Univ., Sapporo (Japan). Hospital

    2001-07-01

    Total body irradiation (TBI) is performed in combination with chemotherapy to kill malignant tumor cells in the body prior to bone marrow transplantation. This study reports the results of dose measurements required for clinical application of the moving table technique to TBI. Since irradiation is performed as the table moves, the authors gathered sufficient basic data for irradiation by measuring output dose, tissue peak dose ratio (TPR), and the relationship between dose rate and movement velocity. The output doses were varied according to dose rate, movement velocity, radiation field, and source-target distance (STD) under these conditions. The authors measured the relationship between the dose rate and the movement velocity with the irradiation field and STD set to fit clinical applications. TPR during irradiation while moving differs from TPR during stationary irradiation, and it was measured according to the method of irradiation. The effect of body thickness was easily corrected by changing the movement velocity during the measurements. The authors measured the dose with a thermoluminescent dosimeter (TLD) during clinical application and confirmed the accuracy of the measurements. TBI with the moving table, it makes possible to perform bilateral irradiation in both posterior-anterior and anterior-posterior directions with the patient in the supine position, to reduce treatment time, to shield the lung well with reproducibility of posture, and to treat with high accuracy. (K.H.)

  20. Dose calculation and in-phantom measurement in BNCT using response matrix method.

    Science.gov (United States)

    Rahmani, Faezeh; Shahriari, Majid

    2011-12-01

    In-phantom measurement of physical dose distribution is very important for Boron Neutron Capture Therapy (BNCT) planning validation. If any changes take place in therapeutic neutron beam due to the beam shaping assembly (BSA) change, the dose will be changed so another group of simulations should be carried out for dose calculation. To avoid this time consuming procedure and speed up the dose calculation to help patients not wait for a long time, response matrix method was used. This procedure was performed for neutron beam of the optimized BSA as a reference beam. These calculations were carried out using the MCNPX, Monte Carlo code. The calculated beam parameters were measured for a SNYDER head phantom placed 10 cm away from beam the exit of the BSA. The head phantom can be assumed as a linear system and neutron beam and dose distribution can be assumed as an input and a response of this system (head phantom), respectively. Neutron spectrum energy was digitized into 27 groups. Dose response of each group was calculated. Summation of these dose responses is equal to a total dose of the whole neutron/gamma spectrum. Response matrix is the double dimension matrix (energy/dose) in which each parameter represents a depth-dose resulted from specific energy. If the spectrum is changed, response of each energy group may be differed. By considering response matrix and energy vector, dose response can be calculated. This method was tested for some BSA, and calculations show statistical errors less than 10%.

  1. FPGA-based smart sensor for online displacement measurements using a heterodyne interferometer.

    Science.gov (United States)

    Vera-Salas, Luis Alberto; Moreno-Tapia, Sandra Veronica; Garcia-Perez, Arturo; de Jesus Romero-Troncoso, Rene; Osornio-Rios, Roque Alfredo; Serroukh, Ibrahim; Cabal-Yepez, Eduardo

    2011-01-01

    The measurement of small displacements on the nanometric scale demands metrological systems of high accuracy and precision. In this context, interferometer-based displacement measurements have become the main tools used for traceable dimensional metrology. The different industrial applications in which small displacement measurements are employed requires the use of online measurements, high speed processes, open architecture control systems, as well as good adaptability to specific process conditions. The main contribution of this work is the development of a smart sensor for large displacement measurement based on phase measurement which achieves high accuracy and resolution, designed to be used with a commercial heterodyne interferometer. The system is based on a low-cost Field Programmable Gate Array (FPGA) allowing the integration of several functions in a single portable device. This system is optimal for high speed applications where online measurement is needed and the reconfigurability feature allows the addition of different modules for error compensation, as might be required by a specific application.

  2. New Method of Online Measurement of Oil and Suspended Material Concentration In Flowing Waste Water

    Science.gov (United States)

    Liao, Hongwei; Xu, Guobing; Xu, Xinqiang; Zhou, Fangde

    2007-06-01

    At present, the most of the measurements of oil and suspended material concentration in waste water measuring are not online surveys. A new method of online measurement of oil and suspended material concentration in flowing waste water is presented. The room experiments and field tests showed that it is suitable to waste water treatment on line. After sampling, It needed to measure immediately the concentration in first time. Then let sample to be in still in 10 - 20 seconds. After that the bulk concentration was measured in second time. Because of the suspended solids having heavy density, they would be dropped from waster water. During ultrasonic operation, emulsify the oil in waster water, the oil and suspended solid would be depart. After that the third time measurement was done. In thus way the concentrations of oil and suspended solids can be measured. At present there are two on-site equipments operating in the Changqing oilfield, and the results are pretty well.

  3. Dose determination with nitro blue tetrazolium containing radiochromic dye films by measuring absorbed and reflected light

    DEFF Research Database (Denmark)

    Kovács, A.; Baranyai, M.; Wojnárovits, L.

    2000-01-01

    Tetrazolium salts as heterocyclic organic compounds are known to form highly coloured, water insoluble formazans by reduction, which can be utilized in radiation processing dosimetry. Radiochromic films containing nitro blue tetrazolium dissolved in a polymer matrix were found suitable for dose...... determination in a wide dose range both by absorbance and reflectance measurements. The concept of measuring reflected light from dose labels has been discussed earlier and emerged recently due to the requirement of introducing semiquantitative label dose indicators for quarantine control. The usefulness...

  4. Absorbed dose measurements in the build-up region of flattened versus unflattened megavoltage photon beams.

    Science.gov (United States)

    De Puysseleyr, Annemieke; Lechner, Wolfgang; De Neve, Wilfried; Georg, Dietmar; De Wagter, Carlos

    2016-06-01

    This study evaluated absorbed dose measurements in the build-up region of conventional (FF) versus flattening filter-free (FFF) photon beams. The absorbed dose in the build-up region of static 6 and 10MV FF and FFF beams was measured using radiochromic film and extrapolation chamber dosimetry for single beams with a variety of field sizes, shapes and positions relative to the central axis. Removing the flattening filter generally resulted in slightly higher relative build-up doses. No considerable impact on the depth of maximum dose was found. Copyright © 2016. Published by Elsevier GmbH.

  5. SU-E-T-481: In Vivo and Post Mortem Animal Irradiation: Measured Vs. Calculated Doses

    Energy Technology Data Exchange (ETDEWEB)

    Heintz, P [Univ New Mexico Radiology Dept., Albuquerque, NM (United States); Heintz, B [Texas Oncology, PA, Southlake, TX (United States); Sandoval, D [University of New Mexico, Albuquerque, NM (United States); Weber, W; Melo, D; Guilmette, R [Lovelace Respiratory Research Institute, Albuquerque, NM (United States)

    2015-06-15

    Purpose: Computerized radiation therapy treatment planning is performed on almost all patients today. However it is seldom used for laboratory irradiations. The first objective is to assess whether modern radiation therapy treatment planning (RTP) systems accurately predict the subject dose by comparing in vivo and decedent dose measurements to calculated doses. The other objective is determine the importance of using a RTP system for laboratory irradiations. Methods: 5 MOSFET radiation dosimeters were placed enterically in each subject (2 sedated Rhesus Macaques) to measure the absorbed dose at 5 levels (carina, lung, heart, liver and rectum) during whole body irradiation. The subjects were treated with large opposed lateral fields and extended distances to cover the entire subject using a Varian 600C linac. CT simulation was performed ante-mortem (AM) and post-mortem (PM). To compare AM and PM doses, calculation points were placed at the location of each dosimeter in the treatment plan. The measured results were compared to the results using Varian Eclipse and Prowess Panther RTP systems. Results: The Varian and Prowess treatment planning system agreed to within in +1.5% for both subjects. However there were significant differences between the measured and calculated doses. For both animals the calculated central axis dose was higher than prescribed by 3–5%. This was caused in part by inaccurate measurement of animal thickness at the time of irradiation. For one subject the doses ranged from 4% to 7% high and the other subject the doses ranged 7% to 14% high when compared to the RTP doses. Conclusions: Our results suggest that using proper CT RTP system can more accurately deliver the prescribed dose to laboratory subjects. It also shows that there is significant dose variation in such subjects when inhomogeneities are not considered in the planning process.

  6. Monitoring of doses in hemodynamic medical team with dosemeters calibrated to measure the personal dose equivalent; Monitoracao das doses na equipe medica de hemodinamica com dosimetro calibrado em equivalente de dose pessoal

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, T.C. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Curso de Ciencias e Tecnicas Nucleares]. E-mail: alonso@cdtn.br; Silva, T.A. da [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)]. E-mail: silvata@cdtn.br

    2005-07-01

    In hemodynamic, the exposure time of the workers to the radiation are larger than in the conventional one. Consequently, the received doses are larger. The dose of the medical team is also affected significantly by the uniqueness of the exams that are accomplished in two ways of irradiation and several angles of incidences, what stands out the need of the dosimeters use with metrologic reliability adapted for such situations. The individual monitoring of the doses received by individuals occupationally exposed to the radiation is accomplished with films dosimeters or thermo luminescent ones, with the main objective to guarantee that the limits of doses are not surpassed. The used in the system Brazilian metrologic system is still the individual dose for photons, in spite of the international recommendations for the use of the equivalent personal dose, that is the greatness adapted to assess the equivalent dose and the effective dose. In this work, the dosimeter composed by the Harshaw-Bicron badge and the detecting thermoluminescent of lithium fluoride was tested and adapted to measure the equivalent of personal dose in the depths 0,07 mm and 10 mm. It was applied in the hemodynamics practices and the doses were compared with those obtained by the routine film dosimeter. The results suggest, for daily use of the interventional services, the indication of the new dosimeter in substitution to the of the type films. (author)

  7. Measurement of radiation dose to ovaries from CT of the head and trunk

    Energy Technology Data Exchange (ETDEWEB)

    Al-Habdhan, M.A.M.; Kinsara, A.R. [King Abdul Aziz Univ., Nuclear Engineering Dept., Jeddah (Saudi Arabia)

    2001-07-01

    With the rise in concern about doses received by patients over recent years, there has been a growing requirement for information on typical doses and the range of dose received during Computerized Tomography (CT). This study was performed for the assessment of radiation dose to the ovaries from various CT protocols for head and trunk imaging. Thermo luminescent dosimeters (TLD) were used for the dosimetry measurement in an anthropomorphic Rando Alderson phantom. The wanted (obligatory) and unwanted (non-useful) radiation doses delivered to the ovaries during CT examinations of head, facial bone, orbits, abdomen, chest, pelvis, neck, nasopharynx, cervical spine, lumber spine and sacroiliac joint were assessed. The results are compared with the corresponding values published in the literature. A comparison of the received dose from CT examinations and general radiography examinations by the ovaries was made. It is found that relatively high doses of unwanted radiation are delivered with computerized tomography. (author)

  8. Potential clinical utility of a fibre optic-coupled dosemeter for dose measurements in diagnostic radiology.

    Science.gov (United States)

    Jones, A Kyle; Hintenlang, David

    2008-01-01

    Many types of dosemeters have been investigated for absorbed dose measurements in diagnostic radiology, including ionisation chambers, metal-oxide semiconductor field-effect transistor dosemeters, thermoluminescent dosemeters, optically stimulated luminescence detectors, film and diodes. Each of the aforementioned dosemeters suffers from a critical limitation, either the need to interrogate, or read, the dosemeter to retrieve dose information or large size to achieve adequate sensitivity. This work presents an evaluation of a fibre optic-coupled dosemeter (FOCD) for use in diagnostic radiology dose measurement. This dosemeter is small, tissue-equivalent and capable of providing true real-time dose information. The FOCD has been evaluated for dose linearity, angular dependence, sensitivity and energy dependence at energies, beam qualities and beam quantities relevant to diagnostic radiology. The FOCD displayed excellent dose linearity and high sensitivity, while exhibiting minimal angular dependence of response. However, the dosemeter does exhibit positive energy dependence, and is subject to attenuation of response when bent.

  9. Bondlines – Online blade measurements (October 2012 and January 2013)

    DEFF Research Database (Denmark)

    McGugan, Malcolm; Chiesura, Gabriele

    Some local deformations in an operating Wind Turbine blade (V80) have been measured during October 2012. Displacement and load values generated between the trailing edge panels at blade radius R9.2m, R10,2m, and R11,2m were obtained. A fluctuating loading of between 100 - 200N existed when the two...... panels were connected, and with a displacement of between 6.5 - 10mm when the panels were free to flex as they do in normal operating conditions. Shear distortion within the main loading spar of the blade (at approximately R10m) showed a fluctuating cross beam shear distortion of about 9mm. The trailing...... edge displacement was re-measured (during January 2013) following a reinforcement of the blade to prevent trailing edge distortion. This trial showed that the new displacement values were below 1mm during similar operating conditions. This report describes the planning for and procurement of hardware...

  10. Sources of variability in OSL dose measurements using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, L.

    2005-01-01

    In luminescence-based measurements of dose distributions in unheated mineral samples, the observed spread in dose values is usually attributed to four main factors: fluctuations in the number of photons counted, incomplete zeroing of any prior trapped charge (including signals arising from thermal...... was designed to deliver a uniform dose to the sample. Thus it was anticipated that statistical fluctuations in the number of photons counted and instrument reproducibility, both quantifiable entities, should be able to account for all the observed variance in the measured dose distributions. We examine...... transfer), heterogeneity in dosimetry, and instrument reproducibility. For correct interpretation of measured dose distributions in retrospective dosimetry, it is important to understand the relative importance of these components, and to establish whether other factors also contribute to the observed...

  11. Measurements of the attenuation of neutron and gamma doses in ordinary and ilmenite concrete shields

    Energy Technology Data Exchange (ETDEWEB)

    Megahid, R.M.; Makarious, A.S.; El-Kolaly, M.A. (Atomic Energy Establishment, Inshas (Egypt). Reactor and Neutron Physics Dept.)

    1980-01-01

    Measurements have been carried out to study the attenuation of neutron and gamma-doses in ordinary and ilmenite concrete shields of densities 2.3 and 4.6 gt. cm/sup -3/ respectively. The attenuation of thermal neutron doses emitted directly from the reactor core and the secondary gamma doses produced from the absorption of these neutrons were evaluated. Measurements were performed using a reactor beam from one of the horizontal channels of the ET-RR-1 reactor. The neutron and gamma doses were monitored be means of Li/sub 2/ B/sub 4/ O/sub 7/: Mn and liF-7 teflon thermoluminescent dosimeters. The measured data give the value of the relative intensities between neutron and gamma doses obtained in these two types of concrete. The contribution of thermal neutrons emitted directly from the reactor core and the secondary gamma from the radiative capture of these neutrons were evaluated.

  12. The web-buffet--development and validation of an online tool to measure food choice.

    Science.gov (United States)

    Bucher, Tamara; Keller, Carmen

    2015-08-01

    To date, no data exist on the agreement of food choice measured using an online tool with subsequent actual consumption. This needs to be shown before food choice, measured by means of an online tool, is used as a dependent variable to examine intake in the general population. A 'web-buffet' was developed to assess food choice. Choice was measured as planned meal composition from photographic material; respondents chose preferred foods and proportions for a main meal (out of a possible 144 combinations) online and the validity was assessed by comparison of a meal composed from a web-buffet with actual food intake 24-48 h later. Furthermore, correlations of food preferences, energy needs and health interest with meals chosen from the web-buffet were analysed. Students: n 106 (Study I), n 32 (Study II). Meals chosen from the web-buffet (mean = 2998 kJ, SD = 471 kJ) agreed with actual consumption (rs = 0.63, P choice in the web-buffet agrees sufficiently well with actual intake to measure food choice as a dependent variable in online surveys. However, we found an average underestimation of subsequent consumption. High correlations of preferences with chosen amounts and an inverse association of health interest with total energy further indicate the validity of the tool. Applications in behavioural nutrition research are discussed.

  13. The Effects of Survey Timing on Student Evaluation of Teaching Measures Obtained Using Online Surveys

    Science.gov (United States)

    Estelami, Hooman

    2015-01-01

    Teaching evaluations are an important measurement tool used by business schools in gauging the level of student satisfaction with the educational services delivered by faculty. The growing use of online teaching evaluations has enabled educational administrators to expand the time period during which student evaluation of teaching (SET) surveys…

  14. Online measurement of fluence and position for protontherapy beams

    Science.gov (United States)

    Benati, C.; Boriano, A.; Bourhaleb, F.; Cirio, R.; Cirrone, G. A. P.; Cornelius, I.; Cuttone, G.; Donetti, M.; Garelli, E.; Giordanengo, S.; Guérin, L.; La Rosa, A.; Luparia, A.; Marchetto, F.; Martin, F.; Meyroneinc, S.; Peroni, C.; Pittà, G.; Raffaele, L.; Sabini, M. G.; Valastro, L.

    2004-09-01

    Tumour therapy with proton beams has been used for several decades in many centres with very good results in terms of local control and overall survival. Typical pathologies treated with this technique are located in head and neck, eye, prostate and in general at big depths or close to critical organs. The Experimental Physics Department of the University of Turin and the local Section of INFN, in collaboration with INFN Laboratori Nazionali del Sud Catania and Centre de Protontherapie de Orsay Paris, have developed detector systems that allow the measurement of beam position and fluence, obtained in real time during beam delivery. The centre in Catania (CATANA: Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) has been treating patients with eye pathologies since spring 2002 using a superconducting cyclotron accelerating protons up to 62 MeV.This kind of treatments need high-resolution monitor systems and for this reason we have developed a 256-strip segmented ionisation chamber, each strip being 400 μm wide, with a total sensitive area 13×13 cm2. The Centre de Protontherapie de Orsay (CPO) has been operational since 1991 and features a synchrocyclotron used for eye and head and neck tumours with proton beams up to 200 MeV. The monitor system has to work on a large surface and for this purpose we have designed a pixel-segmented ionisation chamber, each pixel being 5×5 mm2, for a total active area of 16×16 cm2. The results obtained with two prototypes of the pixel and strip chambers demonstrate that the detectors allow the measurement of fluence and centre of gravity as requested by clinical specifications.

  15. Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria

    Science.gov (United States)

    Titze, Ingo R.; Hunter, Eric J.

    2015-01-01

    Purpose: School-teachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk. Method: Vibration dosimetry is reformulated with the inclusion of collision stress.…

  16. A measurement-based generalized source model for Monte Carlo dose simulations of CT scans

    Science.gov (United States)

    Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun

    2017-03-01

    The goal of this study is to develop a generalized source model for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg–Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1 mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients’ CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology.

  17. Online Dialogue Measurement Index – A Measurement of the Dialogic Orientation of Organizations in the Online Environment

    DEFF Research Database (Denmark)

    Romenti, Stefania; Valentini, Chiara; Murtarelli, Grazia

    on an interdisciplinary conceptualization of dialogue that was developed through a close reading of main studies on dialogue in management, corporate communication, public relations and conversational analysis literatures. The paper presents the index, the results of a pilot test conducted to validate the index scale......Dialogue has been recognized as an important component of organization-stakeholder relations and a communicative sign of openness and responsibility towards others. Still, developing dialogic communications with stakeholders is not an easy task and can also result to be counterproductive when...... dialogic communications create conflicts or bad reputations. Organizations require public relations professionals to measure the results of their communication activities including their dialogic efforts. Yet, dialogic communication measurements are scarce and often incomplete. The purpose of this study...

  18. ELABORATING A MEASUREMENT INSTRUMENT FOR THE FLOW EXPERIENCE DURING ONLINE INFORMATION SEARCH

    Directory of Open Access Journals (Sweden)

    Caraivan Luiza

    2012-12-01

    Full Text Available Flow is a construct imported in marketing research from social sciences in order to examine consumer behavior in the online medium. The construct describes a state of deep involvement in a challenging activity, most frequently characterized by high levels of enjoyment, control and concentration. Researchers found that the degree to which online experience is challenging can be defined, measured, and related well to important marketing variables. As shown by our extensive literature review, flow measurements include antecedents, dimensions and consequences of flow. The present paper represents a detailed description of the construct`s operationalization in the context of online information search. In this respect, our main goal is to produce a basic instrument to evaluate the flow experience of online search, in order to capitalize on the premises of an interactive, complex informational medium – the World Wide Web – and on the consequence of an exploratory informational behavior of users. The instrument is conceived to offer a primal possibility to collect data. The composition, source and significance of the 11 scales used to measure the multiple factors of the flow experience during online search are detailed in this study with the aim to ensure the compliance with scientific rigors and to facilitate correct reports of data related to the reliability and validity of measurements. For further research, we propose factor analysis to test the resulted instrument and to ensure that the measures employed are psychometrically sound. Factor analysis refers to a wide range of statistic techniques used to represent a set of variables in concordance with a reduced number of hypothetical variables called factors. Factorial analysis is used to solve two types of problems: reducing the number of variables to increase data processing speed and identifying hidden patterns in the existent data relations. However, we expect our scales to perform

  19. Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures

    Science.gov (United States)

    Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Porto, L. E.; Ledesma, J. A.; Nascimento, E. X.; Legnani, A.; Andrade, M. E. A.; Khoury, H. J.

    2015-11-01

    This study investigates patient and staff dose measurements in pediatric barium meal series fluoroscopic procedures. It aims to analyze radiographic techniques, measure the air kerma-area product (PKA), and estimate the staff's eye lens, thyroid and hands equivalent doses. The procedures of 41 patients were studied, and PKA values were calculated using LiF:Mg,Ti thermoluminescent dosimeters (TLDs) positioned at the center of the patient's upper chest. Furthermore, LiF:Mg,Cu,P TLDs were used to estimate the equivalent doses. The results showed a discrepancy in the radiographic techniques when compared to the European Commission recommendations. Half of the results of the analyzed literature presented lower PKA and dose reference level values than the present study. The staff's equivalent doses strongly depends on the distance from the beam. A 55-cm distance can be considered satisfactory. However, a distance decrease of ~20% leads to, at least, two times higher equivalent doses. For eye lenses this dose is significantly greater than the annual limit set by the International Commission on Radiological Protection. In addition, the occupational doses were found to be much higher than in the literature. Changing the used radiographic techniques to the ones recommended by the European Communities, it is expected to achieve lower PKA values ​​and occupational doses.

  20. Online evolution reconstruction from a single measurement record with random time intervals for quantum communication

    Science.gov (United States)

    Zhou, Hua; Su, Yang; Wang, Rong; Zhu, Yong; Shen, Huiping; Pu, Tao; Wu, Chuanxin; Zhao, Jiyong; Zhang, Baofu; Xu, Zhiyong

    2017-10-01

    Online reconstruction of a time-variant quantum state from the encoding/decoding results of quantum communication is addressed by developing a method of evolution reconstruction from a single measurement record with random time intervals. A time-variant two-dimensional state is reconstructed on the basis of recovering its expectation value functions of three nonorthogonal projectors from a random single measurement record, which is composed from the discarded qubits of the six-state protocol. The simulated results prove that our method is robust to typical metro quantum channels. Our work extends the Fourier-based method of evolution reconstruction from the version for a regular single measurement record with equal time intervals to a unified one, which can be applied to arbitrary single measurement records. The proposed protocol of evolution reconstruction runs concurrently with the one of quantum communication, which can facilitate the online quantum tomography.

  1. Roller Profile Online Measurement Based on Ultrasonic Circulation Pulse-echo Technology

    Institute of Scientific and Technical Information of China (English)

    WEN Shu-hui; XU Feng-rong

    2007-01-01

    In order to meet the high precision requirement of wide steel strip in industry field, a novel online measurement of roller profile based on sonic circulation and pulse-echo technology was introduced. All kinds of the factors influencing the accuracy of roller profile online measurement were analyzed in detail and error compensation analysis of system was accordingly presented. In order to reduce count error, field program gate array(FPGA) was introduced and a highprecision data acquisition system was designed based on digital phase-shift technology. Experiments indicate that the standard deviation of measure data was 7.27 μm, which showed the feasibility and validity of the proposed method, and realized the roll profile measurement with high precision.

  2. On-Line Measurement of Heat of Combustion of Gaseous Hydrocarbon Fuel Mixtures

    Science.gov (United States)

    Sprinkle, Danny R.; Chaturvedi, Sushil K.; Kheireddine, Ali

    1996-01-01

    A method for the on-line measurement of the heat of combustion of gaseous hydrocarbon fuel mixtures has been developed and tested. The method involves combustion of a test gas with a measured quantity of air to achieve a preset concentration of oxygen in the combustion products. This method involves using a controller which maintains the fuel (gas) volumetric flow rate at a level consistent with the desired oxygen concentration in the combustion products. The heat of combustion is determined form a known correlation with the fuel flow rate. An on-line computer accesses the fuel flow data and displays the heat of combustion measurement at desired time intervals. This technique appears to be especially applicable for measuring heats of combustion of hydrocarbon mixtures of unknown composition such as natural gas.

  3. Measurement of the Space Radiation Dose for the Flight Aircrew at High-Altitude

    Science.gov (United States)

    Lee, Jaewon; Park, Inchun; Kim, Junsik; Lee, Jaejin; Hwang, Junga; Kim, Young-chul

    2014-03-01

    This paper describes an experimental approach to evaluate the effective doses of space radiations at high-altitude by combining the measured data from the Liulin-6K spectrometer loaded onto the air-borne RC-800 cockpit and the calculated data from CARI-6M code developed by FAA. In this paper, 15 exposed dose experiments for the flight missions at a highaltitude above 10 km and 3 experiments at a normal altitude below 4 km were executed over the Korean Peninsula in 2012. The results from the high-altitude flight measurements show a dramatic change in the exposed doses as the altitude increases. The effective dose levels (an average of 15.27 mSv) of aircrew at the high-altitude are an order of magnitude larger than those (an average of 0.30 mSv) of the normal altitude flight. The comparison was made between the measure dose levels and the calculated dose levels and those were similar each other. It indicates that the annual dose levels of the aircrew boarding RC- 800 could be above 1 mSv. These results suggest that a proper procedure to manage the exposed dose of aircrew is required for ROK Air Force.

  4. Radiochromic film calibration for low-energy seed brachytherapy dose measurement

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Hali, E-mail: hamorris@ualberta.ca; Menon, Geetha; Sloboda, Ron S. [Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)

    2014-07-15

    Purpose: Radiochromic film dosimetry is typically performed for high energy photons and moderate doses characterizing external beam radiotherapy (XRT). The purpose of this study was to investigate the accuracy of previously established film calibration procedures used in XRT when applied to low-energy, seed-based brachytherapy at higher doses, and to determine necessary modifications to achieve similar accuracy in absolute dose measurements. Methods: Gafchromic EBT3 film was used to measure radiation doses upwards of 35 Gy from 75 kVp, 200 kVp, 6 MV, and (∼28 keV) I-125 photon sources. For the latter irradiations a custom phantom was built to hold a single I-125 seed. Film pieces were scanned with an Epson 10000XL flatbed scanner and the resulting 48-bit RGB TIFF images were analyzed using both FilmQA Pro software andMATLAB. Calibration curves relating dose and optical density via a rational functional form for all three color channels at each irradiation energy were determined with and without the inclusion of uncertainties in the measured optical densities and dose values. The accuracy of calibration curve variations obtained using piecewise fitting, a reduced film measurement area for I-125 irradiation, and a reduced number of dose levels was also investigated. The energy dependence of the film lot used was also analyzed by calculating normalized optical density values. Results: Slight differences were found in the resulting calibration curves for the various fitting methods used. The accuracy of the calibration curves was found to improve at low doses and worsen at high doses when including uncertainties in optical densities and doses, which may better represent the variability that could be seen in film optical density measurements. When exposing the films to doses > 8 Gy, two-segment piecewise fitting was found to be necessary to achieve similar accuracies in absolute dose measurements as when using smaller dose ranges. When reducing the film measurement

  5. Measurements of Neutron Energy Spectra and Neutron Dose Equivalent Rates of Workplaces in TQNPC-Ⅲ

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Monitoring for neutron doses is one of the important activities for radiation protection. And the information about neutron energy distributions of the measured fields is necessary for the correct

  6. Gamma dose measurements at Zion and Fort Calhoun Stations

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, N.C.; Bunting, R.L.; Nieschmidt, E.B.; Croney, S.T.; Kynaston, R.L.; McIssac, C.V.; Underwood, D.R.

    1979-04-01

    The objective of this study was to provide experimental data to the NRC for evaluation of the gamma radiation fields in personnel access areas within operating LWR's. As partial fulfillment of this objective, data were obtained at two PWR's on in-plant gamma radiation fields in areas such as inside and outside equipment cubicles and spent fuel pool areas. Also, airborne radionuclide concentrations were measured in areas where plant personnel could be working during a refueling outage. Data presented were obtained at the Zion Station operated by Commonwealth Edison Co. and located near Zion, Illinois, and at the Fort Calhoun Station - Unit 1 operated by the Omaha Public Power District and located near Blair, Nebraska.

  7. Online measurement of LHC beam parameters with the ATLAS High Level Trigger

    Science.gov (United States)

    Strauss, E.

    2012-06-01

    We present an online measurement of the LHC beamspot parameters in ATLAS using the High Level Trigger (HLT). When a significant change is detected in the measured beamspot, it is distributed to the HLT. There, trigger algorithms like b-tagging which calculate impact parameters or decay lengths benefit from a precise, up-to-date set of beamspot parameters. Additionally, online feedback is sent to the LHC operators in real time. The measurement is performed by an algorithm running on the Level 2 trigger farm, leveraging the high rate of usable events. Dedicated algorithms perform a full scan of the silicon detector to reconstruct event vertices from registered tracks. The distribution of these vertices is aggregated across the farm and their shape is extracted through fits every 60 seconds to determine the beamspot position, size, and tilt. The reconstructed beamspot values are corrected for detector resolution effects, measured in situ using the separation of vertices whose tracks have been split into two collections. Furthermore, measurements for individual bunch crossings have allowed for studies of single-bunch distributions as well as the behavior of bunch trains. This talk will cover the constraints imposed by the online environment and describe how these measurements are accomplished with the given resources. The algorithm tasks must be completed within the time constraints of the Level 2 trigger, with limited CPU and bandwidth allocations. This places an emphasis on efficient algorithm design and the minimization of data requests.

  8. Comparison of 3-dimensional dose reconstruction system between fluence-based system and dose measurement-guided system.

    Science.gov (United States)

    Nakaguchi, Yuji; Ono, Takeshi; Onitsuka, Ryota; Maruyama, Masato; Shimohigashi, Yoshinobu; Kai, Yudai

    2016-01-01

    COMPASS system (IBA Dosimetry, Schwarzenbruck, Germany) and ArcCHECK with 3DVH software (Sun Nuclear Corp., Melbourne, FL) are commercial quasi-3-dimensional (3D) dosimetry arrays. Cross-validation to compare them under the same conditions, such as a treatment plan, allows for clear evaluation of such measurement devices. In this study, we evaluated the accuracy of reconstructed dose distributions from the COMPASS system and ArcCHECK with 3DVH software using Monte Carlo simulation (MC) for multi-leaf collimator (MLC) test patterns and clinical VMAT plans. In a phantom study, ArcCHECK 3DVH showed clear differences from COMPASS, measurement and MC due to the detector resolution and the dose reconstruction method. Especially, ArcCHECK 3DVH showed 7% difference from MC for the heterogeneous phantom. ArcCHECK 3DVH only corrects the 3D dose distribution of treatment planning system (TPS) using ArcCHECK measurement, and therefore the accuracy of ArcCHECK 3DVH depends on TPS. In contrast, COMPASS showed good agreement with MC for all cases. However, the COMPASS system requires many complicated installation procedures such as beam modeling, and appropriate commissioning is needed. In terms of clinical cases, there were no large differences for each QA device. The accuracy of the compass and ArcCHECK 3DVH systems for phantoms and clinical cases was compared. Both systems have advantages and disadvantages for clinical use, and consideration of the operating environment is important. The QA system selection is depending on the purpose and workflow in each hospital. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  9. Backscattering measuring system for optimization of intravenous laser irradiation dose

    Science.gov (United States)

    Rusina, Tatyana V.; Popov, V. D.; Melnik, Ivan S.; Dets, Sergiy M.

    1996-11-01

    Intravenous laser blood irradiation as an effective method of biostimulation and physiotherapy becomes a more popular procedure. Optimal irradiation conditions for each patient are needed to be established individually. A fiber optics feedback system combined with conventional intravenous laser irradiation system was developed to control of irradiation process. The system consists of He-Ne laser, fiber optics probe and signal analyzer. Intravenous blood irradiation was performed in 7 healthy volunteers and 19 patients with different diseases. Measurements in vivo were related to in vitro blood irradiation which was performed in the same conditions with force-circulated venous blood. Comparison of temporal variations of backscattered light during all irradiation procedures has shown a strong discrepancy on optical properties of blood in patients with various health disorders since second procedure. The best cure effect was achieved when intensity of backscattered light was constant during at least five minutes. As a result, the optical irradiation does was considered to be equal 20 minutes' exposure of 3 mW He-Ne laser light at the end of fourth procedure.

  10. On-Line High Dose-Rate Gamma Ray Irradiation Test of the CCD/CMOS Cameras

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Wan; Jeong, Kyung Min [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    In this paper, test results of gamma ray irradiation to CCD/CMOS cameras are described. From the CAMS (containment atmospheric monitoring system) data of Fukushima Dai-ichi nuclear power plant station, we found out that the gamma ray dose-rate when the hydrogen explosion occurred in nuclear reactors 1{approx}3 is about 160 Gy/h. If assumed that the emergency response robot for the management of severe accident of the nuclear power plant has been sent into the reactor area to grasp the inside situation of reactor building and to take precautionary measures against releasing radioactive materials, the CCD/CMOS cameras, which are loaded with the robot, serve as eye of the emergency response robot. In the case of the Japanese Quince robot system, which was sent to carry out investigating the unit 2 reactor building refueling floor situation, 7 CCD/CMOS cameras are used. 2 CCD cameras of Quince robot are used for the forward and backward monitoring of the surroundings during navigation. And 2 CCD (or CMOS) cameras are used for monitoring the status of front-end and back-end motion mechanics such as flippers and crawlers. A CCD camera with wide field of view optics is used for monitoring the status of the communication (VDSL) cable reel. And another 2 CCD cameras are assigned for reading the indication value of the radiation dosimeter and the instrument. In the preceding assumptions, a major problem which arises when dealing with CCD/CMOS cameras in the severe accident situations of the nuclear power plant is the presence of high dose-rate gamma irradiation fields. In the case of the DBA (design basis accident) situations of the nuclear power plant, in order to use a CCD/CMOS camera as an ad-hoc monitoring unit in the vicinity of high radioactivity structures and components of the nuclear reactor area, a robust survivability of this camera in such intense gamma-radiation fields therefore should be verified. The CCD/CMOS cameras of various types were gamma irradiated at a

  11. Terrestrial gamma radiation dose measurement and health hazard along river Alaknanda and Ganges in India

    Directory of Open Access Journals (Sweden)

    Prerna Sharma

    2014-10-01

    Full Text Available Direct measurement of absorbed dose rate in air due to exposure from outdoor terrestrial γ radiation and assessment of consequent public health hazard continues to be of environmental and public concern. Present study was aimed to establish a baseline data of annual effective dose and to assess the associated health risk from outdoor terrestrial γ radiation along the river Alaknanda and Ganges of India. Terrestrial γ radiation exposure doses (excluding cosmic radiation were measured using a Plastic Scintillation Counter. Absorbed dose rates in air were measured at eight designated locations from Nandprayag to Allahabad along the river. From the average absorbed dose rates, annual effective dose (AED and excess life time cancer risks (ELCR were calculated by standard method. Results showed that absorbed dose rates in air ranged between 81.33 ± 2.34 nSv.h−1 and 144 ± 5.77 nSv.h−1 and calculated AED ranged between 0.10 ± 0.012 mSv.y−1 to 0.18 ± 0.007 mSv.y−1 at the designated locations along these rivers. Calculated ELCR were found in the range of 0.375 × 10−3 to 0.662 × 10−3. Present study measured the outdoor γ radiation levels along the rivers. The calculated annual effective doses and life time cancer risk were found higher than the world average value at higher altitudes. But the measured doses and calculated risks at plains were close to that of reported average values.

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

    Science.gov (United States)

    DeBlois, François; Abdel-Rahman, Wamied; Seuntjens, Jan P; Podgorsak, Ervin B

    2002-03-01

    A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water and bone-equivalent material was used for determining absorbed dose in a bone-equivalent phantom irradiated with clinical radiation beams (cobalt-60 gamma rays; 6 and 18 MV x rays; and 9 and 15 MeV electrons). The dose was determined with the Spencer-Attix cavity theory, using ionization gradient measurements and an indirect determination of the chamber air-mass through measurements of chamber capacitance. The collected charge was corrected for ionic recombination and diffusion in the chamber air volume following the standard two-voltage technique. Due to the hybrid chamber design, correction factors accounting for scatter deficit and electrode composition were determined and applied in the dose equation to obtain absorbed dose in bone for the equivalent homogeneous bone phantom. Correction factors for graphite electrodes were calculated with Monte Carlo techniques and the calculated results were verified through relative air cavity dose measurements for three different polarizing electrode materials: graphite, steel, and brass in conjunction with a graphite collecting electrode. Scatter deficit, due mainly to loss of lateral scatter in the hybrid chamber, reduces the dose to the air cavity in the hybrid PEEC in comparison with full bone PEEC by 0.7% to approximately 2% depending on beam quality and energy. In megavoltage photon and electron beams, graphite electrodes do not affect the dose measurement in the Solid Water PEEC but decrease the cavity dose by up to 5% in the bone-equivalent PEEC even for very thin graphite electrodes (<0.0025 cm). In conjunction with appropriate correction factors determined with Monte Carlo techniques, the uncalibrated hybrid PEEC can be used for measuring absorbed dose in bone material to within 2% for high-energy photon and electron beams.

  13. Online Assessment, Measurement and Evaluation Case Studies from Higher Education, K-12 and Corporate

    Directory of Open Access Journals (Sweden)

    Reviewed by Dr. Adnan BOYACI

    2006-01-01

    Full Text Available With the revolution occurred in communication technologies at the beginning of 1990’s, network technologies have emerged as the challenging parameters accelerating improvements of instructional technologies. Online classrooms and management of them appeared as a new domain which necessitates a new paradigm different from the classical ones. User and instructor friendly learning context and management systems (LCMS have brought new approaches, techniques and tools for the assessment and measurement processes. These approaches, techniques and tools embedded in LCMS have redefined not only the way teachers teach but also students learn. WebCT, Blackboard and eCollege and many others as the online instructional environments have provided new opportunities to construct a coherent instructional system which has never been used as a unique environment any before. Assessment and measurement have been redefined within this framework. The successes of assessment and measurement methodologies or system inevitably depend on conceptualization and then implementation to different educational settings.

  14. MultiProbe Electrical Measurements of Carbon Nanotubes With On-line Raman Scattering

    Science.gov (United States)

    Yablon, Dalia; Yeshua, Talia; Lehmann, Christian; Reich, Stephanie; Strain, Kristin; Campbell, Eleano

    2014-03-01

    A multiprobe scanning probe microscope (SPM) system has been used to perform multiprobe electrical measurement of carbon nanotubes. In this system two probes can be used across an isolated carbon nanotube. A variety of probes have been developed that are compatible with multiprobe operation. These include probes for writing single single walled carbon nanotubes which have a high degree of alignment and this is demonstrated with on-line Raman. The interconnection of the multiprobe system with the Raman System will be described in detail. The combination has the potential to cross the fabrication/measurement gap that will allow for both production and nanocharacterization of such single molecule carbon nanotube molecular devices both with chemically sensitive Raman measurements (with and without plasmonic enhancement) and with on-line electrical transport on isolated carbon nanotubes.

  15. Fricke gel dosimeter with improved sensitivity for low-dose-level measurements.

    Science.gov (United States)

    Vaiente, Mauro; Molina, Wladimir; Silva, Lila Carrizales; Figueroa, Rodolfo; Malano, Francisco; Pérez, Pedro; Santibañez, Mauricio; Vedelago, José

    2016-07-01

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue-equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, independence of dose rate and incident direction, as well as linear dose response. This work presents the development and characterization of an improved Fricke gel system, based on modified chemical compositions, making possible its application in clinical radiology due to its improved sensitivity. Properties of standard Fricke gel dosimeter for high-dose levels are used as a starting point, and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low-dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose-dependency, showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain an adequate dosimeter response for low-dose levels. A suitable composition from among those studied is selected as a good candidate for low-dose-level radiation dosimetry consisting of a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, Xylenol orange, and tridistilled water. Dosimeter samples are prepared in standard vials for in-phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated using typical X-ray tubes for radiology and calibrated Farmer-type ionization chamber is used as reference to measure dose rates inside phantoms at vial locations. Once sensitive material composition is optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels

  16. Surface dose measurements and comparison of unflattened and flattened photon beams

    Directory of Open Access Journals (Sweden)

    Ashokkumar Sigamani

    2016-01-01

    Full Text Available The purpose of this study was to evaluate the central axis dose in the build-up region and the surface dose of a 6 MV and 10 MV flattened photon beam (FB and flattening filter free (FFF therapeutic photon beam for different square field sizes (FSs for a Varian Truebeam linear accelerator using parallel-plate ionization chamber and Gafchromic film. Knowledge of dosimetric characteristics in the build-up region and surface dose of the FFF is essential for clinical care. The dose measurements were also obtained empirically using two different commonly used dosimeters: a p-type photon semiconductor dosimeter and a cylindrical ionization chamber. Surface dose increased linearly with FS for both FB and FFF photon beams. The surface dose values of FFF were higher than the FB FSs. The measured surface dose clearly increases with increasing FS. The FFF beams have a modestly higher surface dose in the build-up region than the FB. The dependence of source to skin distance (SSD is less significant in FFF beams when compared to the flattened beams at extended SSDs.

  17. A Discrete Event System approach to On-line Testing of digital circuits with measurement limitation

    Directory of Open Access Journals (Sweden)

    P.K. Biswal

    2016-09-01

    Full Text Available In the present era of complex systems like avionics, industrial processes, electronic circuits, etc., on-the-fly or on-line fault detection is becoming necessary to provide uninterrupted services. Measurement limitation based fault detection schemes are applied to a wide range of systems because sensors cannot be deployed in all the locations from which measurements are required. This paper focuses towards On-Line Testing (OLT of faults in digital electronic circuits under measurement limitation using the theory of discrete event systems. Most of the techniques presented in the literature on OLT of digital circuits have emphasized on keeping the scheme non-intrusive, low area overhead, high fault coverage, low detection latency etc. However, minimizing tap points (i.e., measurement limitation of the circuit under test (CUT by the on-line tester was not considered. Minimizing tap points reduces load on the CUT and this reduces the area overhead of the tester. However, reduction in tap points compromises fault coverage and detection latency. This work studies the effect of minimizing tap points on fault coverage, detection latency and area overhead. Results on ISCAS89 benchmark circuits illustrate that measurement limitation have minimal impact on fault coverage and detection latency but reduces the area overhead of the tester. Further, it was also found that for a given detection latency and fault coverage, area overhead of the proposed scheme is lower compared to other similar schemes reported in the literature.

  18. The disappearance of the pfotzer-regener maximum in dose equivalent measurements in the stratosphere

    Science.gov (United States)

    Hands, A. D. P.; Ryden, K. A.; Mertens, C. J.

    2016-10-01

    The NASA Radiation Dosimetry Experiment (RaD-X) successfully deployed four radiation detectors on a high-altitude balloon for a period of approximately 20 h. One of these detectors was the RaySure in-flight monitor, which is a solid-state instrument designed to measure ionizing dose rates to aircrew and passengers. Data from RaySure on RaD-X show absorbed dose rates rising steadily as a function of altitude up to a peak at approximately 60,000 feet, known as the Pfotzer-Regener maximum. Above this altitude absorbed dose rates level off before showing a small decline as the RaD-X balloon approaches its maximum altitude of around 125,000 feet. The picture for biological dose equivalent, however, is very different. At high altitudes the fraction of dose from highly ionizing particles increases significantly. Dose from these particles causes a disproportionate amount of biological damage compared to dose from more lightly ionizing particles, and this is reflected in the quality factors used to calculate the dose equivalent quantity. By calculating dose equivalent from RaySure data, using coefficients derived from previous calibrations, we show that there is no peak in the dose equivalent rate at the Pfotzer-Regener maximum. Instead, the dose equivalent rate keeps increasing with altitude as the influence of dose from primary cosmic rays becomes increasingly important. This result has implications for high altitude aviation, space tourism and, due to its thinner atmosphere, the surface radiation environment on Mars.

  19. Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures

    Energy Technology Data Exchange (ETDEWEB)

    Safari, M. J.; Wong, J. H. D.; Ng, K. H., E-mail: ngkh@um.edu.my [Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia and University of Malaya Research Imaging Centre, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Jong, W. L. [Clinical Oncology Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Cutajar, D. L.; Rosenfeld, A. B. [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2015-05-15

    Purpose: The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures. Methods: The calibration and reproducibility of the MOSkin detector and its dependency on different radiation beam qualities were carried out using RQR standard radiation qualities in free-in-air geometry. Studies of the other characterization parameters, such as the dose linearity and dependency on exposure angle, field size, frame rate, depth-dose, and source-to-surface distance (SSD), were carried out using a solid water phantom under a clinical x-ray unit. Results: The MOSkin detector showed good reproducibility (94%) and dose linearity (99%) for the dose range of 2 to 213 cGy. The sensitivity did not significantly change with the variation of SSD (±1%), field size (±1%), frame rate (±3%), or beam energy (±5%). The detector angular dependence was within ±5% over 360° and the dose recorded by the MOSkin detector in different depths of a solid water phantom was in good agreement with the Markus parallel plate ionization chamber to within ±3%. Conclusions: The MOSkin detector proved to be reliable when exposed to different field sizes, SSDs, depths in solid water, dose rates, frame rates, and radiation incident angles within a clinical x-ray beam. The MOSkin detector with water equivalent depth equal to 0.07 mm is a suitable detector for in vivo skin dosimetry during interventional radiology procedures.

  20. Radiation absorbed dose measurement after I-131 metaiodobenzylguanidine treatment in a patient with pheochromycytoma

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Won Il; Kim, Byeung Il; Lee, Jae Sung; Lee, Jung Rim; Choi, Chang Woon; Lim, Sang Moo; Hong, Sung Woon [Korea Cancer Center, Seoul (Korea, Republic of)

    1999-08-01

    The measurement of radiation absorbed dose is useful to predict the response after I-131 labeled metaiodobenzylguanidine (MIBG) therapy and determine therapy dose in patients with unresectable or malignant pheochromocytoma. We estimated the absorbed dose in tumor tissue after high dose I-131 MIBG in a patient with pheochromocytoma using a gamma camera and Medical Internal Radiation Dose (MIRD) formula. A 64-year old female patient with pheochromocytoma who had multiple metastases of mediastinum, right kidney and periaortic lymph nodes, received 74 GBq (200 mCi) of K-131 MIBG. We obtained anterior and posterior images at 0.5, 16, 24, 64 and 145 hours after treatment. Two standard sources of 37 and 74 MBq of I-131 were imaged simulatanously. Cummulated I-131 MIBG uptake in tumor tissue was calculated after the correction of background activity, attenuation, system sensitivity and count loss at a high count rate. The calculated absorbed radiation dose was 32-63 Gy/ 74 GBq, which was lower than the known dose for tumor remission (150-200 Gy). Follow-up studies at 1 month showed minimally reduced tumor size on computed tomography, and mildly reduced I-131 MIBG uptake. We estimated radiation absorbed dose after therapeutic I-131 MIBG using a gamma camera and MIRD formula, which can be peformed in a clinical nuclear medicine laboratory. Our results suggest that the measurement of radiation absorbed dose in I-131 MIBG therapy is feasible as a routine clinical practice that can guide further treatment plan. The accuracy of dose measurement and correlation with clinical outcome should be evaluated further.

  1. Dose equivalent measurements in mixed and time varying radiation fields around high-energy accelerators

    CERN Document Server

    Mayer, S

    2003-01-01

    Measurements of ambient dose equivalent in stray radiation fields behind the shielding of high-energy accelerators are a challenging task. Several radiation components (photons, neutrons, charged particles, muons, etc.), spanning a wide range of energies, contribute to the total dose equivalent. The radiation fields are produced by beam losses interacting with structural material during the acceleration or at the ejection to experimental areas or other accelerators. The particle beam is usually not continuous but separated in "bunches" or pulses, which further complicates dose measurements at high-energy accelerators. An ideal dosimeter for operational radiation protection should measure dose equivalent for any composition of radiation components in the entire energy range even when the field is strongly pulsed. The objective of this work was to find out if an ionisation chamber operated as a "recombination chamber" and a TEPC instrument using the variance-covariance method ("Sievert Instrument") are capable ...

  2. Dose equivalent measurements in mixed and time varying radiation fields around high-energy accelerators

    CERN Document Server

    Mayer, S

    2003-01-01

    Measurements of ambient dose equivalent in stray radiation fields behind the shielding of high-energy accelerators are a challenging task. Several radiation components (photons, neutrons, charged particles, muons, etc.), spanning a wide range of energies, contribute to the total dose equivalent. The radiation fields are produced by beam losses interacting with structural material during the acceleration or at the ejection to experimental areas or other accelerators. The particle beam is usually not continuous but separated in "bunches" or pulses, which further complicates dose measurements at high-energy accelerators. An ideal dosimeter for operational radiation protection should measure dose equivalent for any composition of radiation components in the entire energy range even when the field is strongly pulsed. The objective of this work was to find out if an ionisation chamber operated as a "recombination chamber" and a TEPC instrument using the variance-covariance method ("Sievert Instrument") are capable ...

  3. Measurement of neutron dose equivalent to proton therapy patients outside of the proton radiation field

    CERN Document Server

    Yan, X; Köhler, A; Newhauser, W D

    2002-01-01

    Measurements of neutron dose equivalent values and neutron spectral fluences close to but outside of the therapeutic proton radiation field are presented. The neutron spectral fluences were determined at five locations with Bonner sphere measurements and established by unfolding techniques. More than 50 additional neutron dose equivalent values were measured with LiI and BF sub 3 thermal neutron detectors surrounded by a 25 cm polyethylene moderating sphere. For a large-field treatment, typical values of neutron dose equivalent per therapeutic proton absorbed dose, H/D, at 50 cm distance from isocenter, range from 1 mSv/Gy (at 0 deg.with respect to the proton beam axis) to 5 mSv/Gy (at 90 deg.). Experiments reveal that H/D varies significantly with the treatment technique, e.g., patient orientation, proton beam energy, and range-modulation. The relative uncertainty in H/D values is approximately 40% (one standard deviation).

  4. Radiation protection in medicine (542) comparison of different dosimetry systems for dose measurements in diagnostic radiology

    Energy Technology Data Exchange (ETDEWEB)

    Milkovic, D. [Srebrnjak, Specialized Hospital for Respiratory System Diseases in Children and Youth, Zagreb (Croatia); Ranogajec-Komor, M.; Miljanic, S.; Knezevic, Z.; Krpan, K. [Ruder Boskovic Institute, Zagreb (Croatia)

    2006-07-01

    The dose measurement on patients in X-ray diagnostic is not simple, because low doses with low and various energies have to be measured. The aim of this preliminary study was to compare high sensitivity thermoluminescent dosimeter (T.L.D.) (LiF:Mg,Cu,P) and radio-photoluminescent (R.P.L.) glass dosimeters for dose measurements in routine X-ray diagnostic of chest of children. The energy dependence of the dosimeters was investigated in Secondary Standard Dosimetry Laboratory (SSDL). The energy range was 33- 65 keV mean energy, the dosimeters were placed free in air and on the water phantom. The results were compared to calculated values of Hp(10). The next step was the irradiation in a routine X-ray diagnostic unit. Irradiations were performed by the Shimadzu X-ray unit. The selected irradiation conditions were the same as that most commonly used for baby examinations. Doses were measured with dosimeters placed free-in-air and also with the dosimeters placed on the water phantom and baby phantom. The results show that the R.P.L. glass dosimeters and LiF:Mg,Cu,P based T.L.D. are suitable for low dose measurements in X-ray diagnostic. The uncertainty of dose determination is mainly caused by the energy dependence of dosimeters. (authors)

  5. Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT).

    Science.gov (United States)

    Cecilia, A; Baccaro, S; Cemmi, A; Colli, V; Gambarini, G; Rosi, G; Scolari, L

    2004-01-01

    A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF2:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH3CH(NH2)COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT.

  6. Radiation dose to children in diagnostic radiology. Measurements and methods for clinical optimisation studies

    Energy Technology Data Exchange (ETDEWEB)

    Almen, A.J.

    1995-09-01

    A method for estimating mean absorbed dose to different organs and tissues was developed for paediatric patients undergoing X-ray investigations. The absorbed dose distribution in water was measured for the specific X-ray beam used. Clinical images were studied to determine X-ray beam positions and field sizes. Size and position of organs in the patient were estimated using ORNL phantoms and complementary clinical information. Conversion factors between the mean absorbed dose to various organs and entrance surface dose for five different body sizes were calculated. Direct measurements on patients estimating entrance surface dose and energy imparted for common X-ray investigations were performed. The examination technique for a number of paediatric X-ray investigations used in 19 Swedish hospitals was studied. For a simulated pelvis investigation of a 1-year old child the entrance surface dose was measured and image quality was estimated using a contrast-detail phantom. Mean absorbed doses to organs and tissues in urography, lung, pelvis, thoracic spine, lumbar spine and scoliosis investigations was calculated. Calculations of effective dose were supplemented with risk calculations for special organs e g the female breast. The work shows that the examination technique in paediatric radiology is not yet optimised, and that the non-optimised procedures contribute to a considerable variation in radiation dose. In order to optimise paediatric radiology there is a need for more standardised methods in patient dosimetry. It is especially important to relate measured quantities to the size of the patient, using e g the patient weight and length. 91 refs, 17 figs, 8 tabs.

  7. Development of a synthetic single crystal diamond dosimeter for dose measurement of clinical proton beams

    Science.gov (United States)

    Moignier, Cyril; Tromson, Dominique; de Marzi, Ludovic; Marsolat, Fanny; García Hernández, Juan Carlos; Agelou, Mathieu; Pomorski, Michal; Woo, Romuald; Bourbotte, Jean-Michel; Moignau, Fabien; Lazaro, Delphine; Mazal, Alejandro

    2017-07-01

    The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves. The simulations indicated that the diamond crystal alone, with a small e AV of just 5 µm, already affects the dose at Bragg peak position (Bragg peak dose) by more than 2% with respect to the Bragg peak dose deposited in water. The optimal design that resulted from the Monte Carlo simulations consists of a diamond crystal of 1 mm in width and 150 µm in thickness with the front silver resin, enclosed by a water-equivalent packaging. This design leads to a deviation between the Bragg peak dose from the full detector modeling and the Bragg peak dose deposited in water of less than 1.2%. Based on those optimizations, an SCDD-Pro prototype was built and evaluated in broad passive scattering proton beams. The experimental evaluation led to probed SCDD-Pro repeatability, dose rate dependence and linearity, that were better than 0.2%, 0.4% (in the 1.0-5.5 Gy min-1 range) and 0.4% (for dose higher than 0.05 Gy), respectively. The depth-dose curves in the 90-160 MeV energy range, measured with the SCDD-Pro without applying any correction, were in good agreement with those measured using a commercial IBA PPC05 plane-parallel ionization chamber, differing by less than 1.6%. The experimental results confirmed that this SCDD-Pro is suitable for measurements with standard electrometers and that the depth-dose curve perturbation is negligible, with no energy dependence and no significant dose rate

  8. On-line electrochemical measurements of cerebral hypoxanthine of freely moving rats

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZiPin; LIN YuQing; MAO LanQun

    2009-01-01

    This study demonstrates an on-line method for continuous measurements of cerebral hypoxanthine in the freely moving rats with integration of selective electrochemical biosensing with in vivo microdialysis sampling. The selective electrochemical biosensing is achieved by using xanthine oxidase (XOD) as the specific sensing element and Prussian blue (PB) as the electrocatalyst for the reduction of H_2O_2 generated from the oxidase-catalyzed reaction. The method is virtually interference-free from the coexisting electroactive species in the brain and exhibits a good stability and reproducibility. Upon integrated with in vivo microdialysis, the on-line method is well suitable for continuous measurements of cerebral hypoxanthine of freely moving rats, which is illustrated by the measurements of the microdialysates after the hypoxanthine standard was externally infused into the rat brain. This study essen-tially offers a facile on-line electrochemical approach to continuous measurements of cerebral hypoxanthine and could find some interesting applications in physiological and pathological investigations associated with hypoxanthine.

  9. On-line electrochemical measurements of cerebral hypoxanthine of freely moving rats

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This study demonstrates an on-line method for continuous measurements of cerebral hypoxanthine in the freely moving rats with integration of selective electrochemical biosensing with in vivo microdialysis sampling. The selective electrochemical biosensing is achieved by using xanthine oxidase (XOD) as the specific sensing element and Prussian blue (PB) as the electrocatalyst for the reduction of H2O2 generated from the oxidase-catalyzed reaction. The method is virtually interference-free from the co-existing electroactive species in the brain and exhibits a good stability and reproducibility. Upon integrated with in vivo microdialysis, the on-line method is well suitable for continuous measurements of cerebral hypoxanthine of freely moving rats, which is illustrated by the measurements of the microdi-alysates after the hypoxanthine standard was externally infused into the rat brain. This study essentially offers a facile on-line electrochemical approach to continuous measurements of cerebral hypoxanthine and could find some interesting applications in physiological and pathological investigations associated with hypoxanthine.

  10. TU-F-CAMPUS-J-05: Fast Volumetric MRI On An MRI-Linac Enables On-Line QA On Dose Deposition in the Patient

    Energy Technology Data Exchange (ETDEWEB)

    Crijns, S; Glitzner, M; Kontaxis, C; Maenhout, M; Bol, G; Lagendijk, J; Raaymakers, B [University Medical Center Utrecht, Utrecht (Netherlands); Senneville, B Denis de [University Medical Center Utrecht, Utrecht (Netherlands); Mathematical Institute of Bordeaux, University of Bordeaux, Talence Cedex (France)

    2015-06-15

    Purpose: The introduction of the MRI-linac in radiotherapy brings MRI-guided treatment with daily plan adaptions within reach. This paradigm demands on-line QA. With its ability to perform continuous volumetric imaging in an outstanding soft-tissue contrast, the MRI- linac promises to elucidate the dose deposition process during a treatment session. Here we study for a prostate case how dynamic MRI combined with linac machine parameters and a fast dose-engine can be used for on-line dose accumulation. Methods: Prostate imaging was performed in healthy volunteer on a 1.5T MR-scanner (Philips, Best, NL) according to a clinical MR-sim protocol, followed by 10min of dynamic imaging (FLASH, 4s/volume, FOV 40×40×12cm{sup 3}, voxels 3×3×3mm{sup 3}, TR/TE/α=3.5ms/1.7ms/5°). An experienced radiation oncologist made delineations, considering the prostate CTV. Planning was performed on a two-compartment pseudoCT (air/water density) according to clinical constraints (77Gy in PTV) using a Monte-Carlo (MC) based TPS that accounts for magnetic fields. Delivery of one fraction (2.2Gy) was simulated on an emulator for the Axesse linac (Elekta, Stockholm, SE). Machine parameters (MLC settings, gantry angle, dose rate, etc.) were recorded at 25Hz. These were re-grouped per dynamic volume and fed into the MC-engine to calculate a dose delivered for each of the dynamics. Deformations derived from non-rigid registration of each dynamic against the first allowed dose accumulation on a common reference grid. Results: The DVH parameters on the PTV compared to the optimized plan showed little changes. Local deformations however resulted in local deviations, primarily around the air/rectum interface. This clearly indicates the potential of intra-fraction adaptations based on the accumulated dose. Application in each fraction helps to track the influence of plan adaptations to the eventual dose distribution. Calculation times were about twice the delivery time. Conclusion: The current

  11. SU-E-J-146: A Research of PET-CT SUV Range for the Online Dose Verification in Carbon Ion Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Sun, L; Hu, W [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China); Moyers, M [Shanghai Proton and Heavy Ion Center, Colton, CA (China); Zhao, J [Shanghai Proton and Heavy Ion Center, Shanghai, Shanghai (China); Hsi, W [Shanghai Proton and Heavy Ion Center, Shanghai (China)

    2015-06-15

    Purpose: Positron-emitting isotope distributions can be used for the image fusion of the carbon ion planning CT and online target verification PETCT, after radiation in the same decay period,the relationship between the same target volume and the SUV value of different every single fraction dose can be found,then the range of SUV for the radiation target could be decided.So this online range also can provide reference for the correlation and consistency in planning target dose verification and evaluation for the clinical trial. Methods: The Rando head phantom can be used as real body,the 10cc cube volume target contouring is done,beam ISO Center depth is 7.6cm and the 90 degree fixed carbon ion beams should be delivered in single fraction effective dose of 2.5GyE,5GyE and 8GyE.After irradiation,390 seconds later the 30 minutes PET-CT scanning is performed,parameters are set to 50Kg virtual weight,0.05mCi activity.MIM Maestro is used for the image processing and fusion,five 16mm diameter SUV spheres have been chosen in the different direction in the target.The average SUV in target for different fraction dose can be found by software. Results: For 10cc volume target,390 seconds decay period,the Single fraction effective dose equal to 2.5Gy,Ethe SUV mean value is 3.42,the relative range is 1.72 to 6.83;Equal to 5GyE,SUV mean value is 9.946,the relative range is 7.016 to 12.54;Equal or above to 8GyE,SUV mean value is 20.496,the relative range is 11.16 to 34.73. Conclusion: Making an evaluation for accuracy of the dose distribution using the SUV range which is from the planning CT with after treatment online PET-CT fusion for the normal single fraction carbon ion treatment is available.Even to the plan which single fraction dose is above 2GyE,in the condition of other parameters all the same,the SUV range is linearly dependent with single fraction dose,so this method also can be used in the hyper-fraction treatment plan.

  12. TH-C-19A-04: Commissioning and Validation of EBT3 Gafchromic Films for Measurements of Dose Profiles and Integrals of Dose in Small Fields

    Energy Technology Data Exchange (ETDEWEB)

    Dufreneix, S; Bordy, J; Delaunay, F; Daures, J; Gouriou, J; Le, Roy M; Ostrowsky, A; Rapp, B; Sommier, L [CEA, LIST, Laboratoire National Henri Becquerel, Gif-sur-Yvette (France)

    2014-06-15

    Purpose: The use of a primary dosimeter larger than the radiation field gives access to the integral of dose over a specified surface normal to the beam. If a relative dose profile of the beam is well known, it is then possible to calculate the distribution of the absorbed dose at any point on the considered surface. This study aims at validating the use of EBT3 gafchromic films for the measurement of 2D dose distribution and integrals of dose in small fields for such use. Methods: New EBT3 films have been fully characterized: the response versus energy, dose-rate and dose has been investigated. Profiles measured in circular field with a diameter of 20 mm have been compared to the ones measured with a diamond detector developed at CEA/LIST/LCD. The ratio of dose area products measured with EBT3 on a 6 mm and 30 mm diameter surface has been compared to the ratio measured with primary dosimeters (calorimeters) and calculated with Monte Carlo simulations. Results: There was no significant difference between the dose-calibration curves in a 6 MV and a 60Co beam. Deviation was within uncertainty bars when the dose rate inside a pulse was divided by a factor of 80 in the 6 MV photon beam. Profiles in small fields are in good agreement with the diamond profiles. Dose area product ratios obtained with EBT3, calorimeters and simulations are within 1%. Conclusion: EBT3 films are good candidates for the measurement of relative dose distribution in small fields as long as the average of several films is considered. They can be used in association with primary measurements to determinate dosimetric references in small fields and to transfer them to the end user.

  13. Reinitiating Warfarin: Relationships Between Dose and Selected Patient, Clinical and Hospital Measures

    Science.gov (United States)

    Leonhard, Lucas G.; Berg, Richard L.; Burmester, James K.; Mazza, Joseph J.; Schmelzer, John R.; Yale, Steven H.

    2015-01-01

    Background Warfarin is an oral anticoagulant used in the long-term treatment/prevention of venothromboembolic disease. Patients undergoing elective surgical and non-surgical procedures may require temporary warfarin discontinuation followed by reinitiation after their procedure. Because little information is available regarding best methods for warfarin reinitiation, we investigated current practices to inform management decisions. Methods Subjects were required to have a known and stable warfarin dose prior to discontinuation, which was operationalized by requiring, within 7-days prior to discontinuation, that they have at least one INR in therapeutic range (2.0–3.5), no INR(s) out of range, and no more than a 15% change in warfarin dose. Stable dose prior to discontinuation was defined as the average daily dose received in the 7 days immediately prior to discontinuation. Reinitiation dose was defined as the average daily dose received in the first 3 days after warfarin was restarted. Subjects were divided into three groups based on whether they received approximately the same, a higher, or a lower dose at reinitiation and were also grouped by calendar time into three distinct periods that reflected differing levels of availability of electronic and patient care data that may impact reinitiation dose decisions. These groupings facilitated analyses and descriptions of trends in reinitiation dosing and supported other analyses, including tests for association between dose group and selected subject demographic, clinical, medication and hospitalization measures. All study data were abstracted from Marshfield Clinic electronic patient care and administrative databases and electronic patient care databases from Ministry St. Joseph’s Hospital (Marshfield, WI). Results We identified 205 subjects with warfarin temporarily discontinued between 1994 and 2012: 99 subjects in same dose group, 32 subjects in the low group, and 74 subjects in the high group. Because

  14. VMAT QA: Measurement-guided 4D dose reconstruction on a patient

    Energy Technology Data Exchange (ETDEWEB)

    Nelms, Benjamin E.; Opp, Daniel; Robinson, Joshua; Wolf, Theresa K.; Zhang, Geoffrey; Moros, Eduardo; Feygelman, Vladimir [Canis Lupus LLC, Merrimac, Wisconsin 53561 (United States); Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Live Oak Technologies LLC, Kirkwood, Missouri 63122 (United States); Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States)

    2012-07-15

    Purpose: To develop and validate a volume-modulated arc therapy (VMAT) quality assurance (QA) tool that takes as input a time-resolved, low-density ({approx}10 mm) cylindrical surface dose map from a commercial helical diode array, and outputs a high density, volumetric, time-resolved dose matrix on an arbitrary patient dataset. This first validation study is limited to a homogeneous 'patient.'Methods: A VMAT treatment is delivered to a diode array phantom (ARCCHECK, Sun Nuclear Corp., Melbourne, FL). 3DVH software (Sun Nuclear) derives the high-density volumetric dose using measurement-guided dose reconstruction (MGDR). MGDR cylindrical phantom results are then used to perturb the three-dimensional (3D) treatment planning dose on the patient dataset, producing a semiempirical volumetric dose grid. Four-dimensional (4D) dose reconstruction on the patient is also possible by morphing individual sub-beam doses instead of the composite. For conventional (3D) dose comparison two methods were developed, using the four plans (Multi-Target, C-shape, Mock Prostate, and Head and Neck), including their structures and objectives, from the AAPM TG-119 report. First, 3DVH and treatment planning system (TPS) cumulative point doses were compared to ion chamber in a cube water-equivalent phantom ('patient'). The shape of the phantom is different from the ARCCHECK and furthermore the targets were placed asymmetrically. Second, coronal and sagittal absolute film dose distributions in the cube were compared with 3DVH and TPS. For time-resolved (4D) comparisons, three tests were performed. First, volumetric dose differences were calculated between the 3D MGDR and cumulative time-resolved patient (4D MGDR) dose at the end of delivery, where they ideally should be identical. Second, time-resolved (10 Hz sampling rate) ion chamber doses were compared to cumulative point dose vs time curves from 4D MGDR. Finally, accelerator output was varied to assess the linearity of

  15. The MapCHECK Measurement Uncertainty function and its effect on planar dose pass rates.

    Science.gov (United States)

    Bailey, Daniel W; Spaans, Jason D; Kumaraswamy, Lalith K; Podgorsak, Matthew B

    2016-03-08

    Our study aimed to quantify the effect of the Measurement Uncertainty function on planar dosimetry pass rates, as measured and analyzed with the Sun Nuclear Corporation MapCHECK 2 array and its associated software. This optional function is toggled in the program preferences of the software (though turned on by default upon installation), and automatically increases the dose difference tolerance defined by the user for each planar dose comparison. Dose planes from 109 static-gantry IMRT fields and 40 VMAT arcs, of varying modulation complexity, were measured at 5 cm water-equivalent depth in the MapCHECK 2 diode array, and respective calculated dose planes were exported from a commercial treatment planning system. Planar dose comparison pass rates were calculated within the Sun Nuclear Corporation analytic software using a number of calculation parameters, including Measurement Uncertainty on and off. By varying the percent difference (%Diff) criterion for similar analyses performed with Measurement Uncertainty turned off, an effective %Diff criterion was defined for each field/arc corresponding to the pass rate achieved with Measurement Uncertainty turned on. On average, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.8%-1.1% for 3%/3 mm analysis, depending on plan type and calculation technique (corresponding to an average change in pass rate of 1.0%-3.5%, and a maximum change of 8.7%). At the 2%/2 mm level, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.7%-1.2% on average, again depending on plan type and calculation technique (corresponding to an average change in pass rate of 3.5%-8.1%, and a maximum change of 14.2%). The largest increases in pass rate due to the Measurement Uncertainty function are generally seen with poorly matched planar dose comparisons, while the function has a notably smaller effect as pass rates approach 100%. The Measurement Uncertainty function, then, may

  16. Measurement of Thyroid Dose by TLD arising from Radiotherapy of Breast Cancer Patients from Supraclavicular Field.

    Science.gov (United States)

    Farhood, B; Bahreyni Toossi, M T; Vosoughi, H; Khademi, S; Knaup, C

    2016-09-01

    Breast cancer is the most frequently diagnosed cancer and the leading global cause of cancer death among women worldwide. Radiotherapy plays a significant role in treatment of breast cancer and reduces locoregional recurrence and eventually improves survival. The treatment fields applied for breast cancer treatment include: tangential, axillary, supraclavicular and internal mammary fields. In the present study, due to the presence of sensitive organ such as thyroid inside the supraclavicular field, thyroid dose and its effective factors were investigated. Thyroid dose of 31 female patients of breast cancer with involved supraclavicular lymph nodes which had undergone radiotherapy were measured. For each patient, three TLD-100 chips were placed on their thyroid gland surface, and thyroid doses of patients were measured. The variables of the study include shield shape, the time of patient's setup, the technologists' experience and qualification. Finally, the results were analyzed by ANOVA test using SPSS 11.5 software. The average age of the patients was 46±10 years. The average of thyroid dose of the patients was 140±45 mGy (ranged 288.2 and 80.8) in single fraction. There was a significant relationship between the thyroid dose and shield shape. There was also a significant relationship between the thyroid dose and the patient's setup time. Beside organ at risk such as thyroid which is in the supraclavicular field, thyroid dose possibility should be reduced. For solving this problem, an appropriate shield shape, the appropriate time of the patient's setup, etc. could be considered.

  17. Energy spectrum measurement and dose rate estimation of natural neutrons in Tibet region

    Institute of Scientific and Technical Information of China (English)

    吴建华; 徐勇军; 刘森林; 汪传高

    2015-01-01

    In this work, natural neutron spectra at nine sites in Tibet region were measured using a multi-sphere neutron spectrometer. The altitude-dependence of the spectra total fluence rate and ambient dose equivalent rate were analyzed. From the normalized natural neutron spectra at different altitudes, the spectrum fractions for neutrons of greater than 0.1 MeV do not differ obviously, while those of the thermal neutrons differ greatly from each other. The total fluence rate, effective dose rate and the ambient dose equivalent rate varied with the altitude according to an exponential law.

  18. The online tourist fraud: the new measures of technological investigation in Spain

    Directory of Open Access Journals (Sweden)

    M.ª Belén AIGE

    2017-07-01

    Full Text Available The present article is about an examination of the new technological measures for the investigation, created by the Organic Act (Ley Orgánica 13/2015, of 5th of October. These measures will serve us to improve de criminal investigation, especially on those crimes that are done by technological means, but also for the traditional crimes. Specifically, we are going to make an especial reference to the tourist fraud, which affects both consumers and entrepreneurs. This fraud is especially notable in the online contracts, as we will see above, because those contracts have increased the number of online frauds in the last years; in the tourism I am referring to the stealing of personal data and the creation of ghost companies or non-existent offers. In first place, we are going to talk about the advantages and disadvantages of the online contracts, and also about the real necessity of new investigation means that finally have been satisfied with the introduction of the new technological measures of investigation, which we are going to analyse: the computerized undercover agent, the interception of the telematics and telephone communications, the recording of oral communications by electronic devices, the tracking, localization and recording images devices, the registry of mass storage devices and the remote registry of computer equipment. 

  19. Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

    NARCIS (Netherlands)

    M.R. Germans; P.C. de Witt Hamer; L.J. van Boven; K.A.H. Zwinderman; G.J. Bouma

    2010-01-01

    (1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of

  20. Measurement of radiation dose at the north interaction point of BEPCⅡ

    Institute of Scientific and Technical Information of China (English)

    MO Xiao-Hu; ZHANG Jian-Yong; ZHANG Tian-Bao; ZHANG Qing-Jiang; Achasov Mikhail; FU Cheng-Dong; Muchnoi Nikolay; QIN Qing; QU Hua-Min; WANG Yi-Fang; WU Jing-Min; XU Jin-Qiang; YU Bo-Xiang

    2009-01-01

    The technique details for measuring radiation dose are expounded.The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation.In addition, the photon radiation level move as background for future experiments is measured by a NaI(T1) detector.

  1. Measuring and Improving Physician Knowledge of Safety Risks Using Traditional and Online Methods in Pharmacovigilance.

    Science.gov (United States)

    Liede, Alexander; Amelio, Justyna; Bennett, James; Goodman, Helen; Peters, Pamela M; Barber, Rebecca; Kehler, Elizabeth; Michael Sprafka, J

    2017-01-01

    Traditional methods for assessing prescriber knowledge can take several years to deliver results. This study was undertaken to obtain insights into the potential for using existing online communities to educate prescribers on therapy-related safety risks. The aim of this study was to describe approaches to measuring prescribers' knowledge of safety risk (osteonecrosis of the jaw) outlined in the European Medicine Agency's summary of product characteristics for denosumab (XGEVA(®)). Short multiple-choice online instruments were administered as (1) a two-round cross-sectional survey fielded in January 2013-May 2015 (traditional, nine European countries, study duration: 3 years), (2) a survey targeting the online Medscape community (seven European countries, study duration: 3 weeks), and (3) a continuing medical education module with pre-/post-assessment in an online Medscape community (Medscape Education, USA). All respondents were oncologists; treated five or more patients with bone metastases from solid tumours in the previous 3 months; and prescribed denosumab within the previous 12 months. Medscape (a WebMD company, New York, NY, USA) is the leading online medical information resource, serving approximately 3 million physicians worldwide and 400,000 within Europe. In the traditional 29-month study, 420 (n = 210 per round; 14% of screened physicians) individuals participated. Knowledge levels exceeded 75% correct on five questions (incidence of osteonecrosis of the jaw, concomitant risk factors and prevention of osteonecrosis of the jaw during denosumab treatment, importance of ensuring oral hygiene, and care for patients who have or develop osteonecrosis of the jaw) with less awareness of optimal osteonecrosis of the jaw treatment. The Medscape survey (n = 207; 32.1% of 645 eligible) provided similar results in a 3-week post-survey launch. The Medscape Education study (n = 264) documented knowledge acquisition. Assessments that target physicians through online

  2. Towards the development of a hybrid-integrated chip interferometer for online surface profile measurements.

    Science.gov (United States)

    Kumar, P; Martin, H; Jiang, X

    2016-06-01

    Non-destructive testing and online measurement of surface features are pressing demands in manufacturing. Thus optical techniques are gaining importance for characterization of complex engineering surfaces. Harnessing integrated optics for miniaturization of interferometry systems onto a silicon wafer and incorporating a compact optical probe would enable the development of a handheld sensor for embedded metrology applications. In this work, we present the progress in the development of a hybrid photonics based metrology sensor device for online surface profile measurements. The measurement principle along with test and measurement results of individual components has been presented. For non-contact measurement, a spectrally encoded lateral scanning probe based on the laser scanning microscopy has been developed to provide fast measurement with lateral resolution limited to the diffraction limit. The probe demonstrates a lateral resolution of ∼3.6 μm while high axial resolution (sub-nanometre) is inherently achieved by interferometry. Further the performance of the hybrid tuneable laser and the scanning probe was evaluated by measuring a standard step height sample of 100 nm.

  3. Removal of correlated noise online for in situ measurements by using multichannel magnetic resonance sounding system

    Science.gov (United States)

    Lin, Tingting; Zhang, Siyuan; Zhang, Yang; Wan, Ling; Lin, Jun

    2017-01-01

    Compared with the other geophysical approaches, magnetic resonance sounding (MRS) technique is direct and nondestructive in subsurface water exploration. It provides water content distribution and estimates hydrogeological properties. The biggest challenge is that MRS measurement always suffers bad signal-to-noise ratio, and it can be carried out only far from sources of noise. To solve this problem, a series of de-noising methods are developed. However, most of them are post-processing, leading the data quality uncontrolled for in situ measurements. In the present study, a new approach that removal of correlated noise online is found to overcome the restriction. Based on LabVIEW, a method is provided to enable online data quality control by the way of realizing signal acquisition and noise filtering simultaneously. Using one or more reference coils, adaptive noise cancellation based on LabVIEW to eliminate the correlated noise is available for in situ measurements. The approach was examined through numerical simulation and field measurements. The correlated noise is mitigated effectively and the application of MRS measurements is feasible in high-level noise environment. The method shortens the measurement time and improves the measurement efficiency.

  4. FPGA-Based Smart Sensor for Online Displacement Measurements Using a Heterodyne Interferometer

    Directory of Open Access Journals (Sweden)

    Eduardo Cabal-Yepez

    2011-08-01

    Full Text Available The measurement of small displacements on the nanometric scale demands metrological systems of high accuracy and precision. In this context, interferometer-based displacement measurements have become the main tools used for traceable dimensional metrology. The different industrial applications in which small displacement measurements are employed requires the use of online measurements, high speed processes, open architecture control systems, as well as good adaptability to specific process conditions. The main contribution of this work is the development of a smart sensor for large displacement measurement based on phase measurement which achieves high accuracy and resolution, designed to be used with a commercial heterodyne interferometer. The system is based on a low-cost Field Programmable Gate Array (FPGA allowing the integration of several functions in a single portable device. This system is optimal for high speed applications where online measurement is needed and the reconfigurability feature allows the addition of different modules for error compensation, as might be required by a specific application.

  5. FPGA-Based Smart Sensor for Online Displacement Measurements Using a Heterodyne Interferometer

    Science.gov (United States)

    Vera-Salas, Luis Alberto; Moreno-Tapia, Sandra Veronica; Garcia-Perez, Arturo; de Jesus Romero-Troncoso, Rene; Osornio-Rios, Roque Alfredo; Serroukh, Ibrahim; Cabal-Yepez, Eduardo

    2011-01-01

    The measurement of small displacements on the nanometric scale demands metrological systems of high accuracy and precision. In this context, interferometer-based displacement measurements have become the main tools used for traceable dimensional metrology. The different industrial applications in which small displacement measurements are employed requires the use of online measurements, high speed processes, open architecture control systems, as well as good adaptability to specific process conditions. The main contribution of this work is the development of a smart sensor for large displacement measurement based on phase measurement which achieves high accuracy and resolution, designed to be used with a commercial heterodyne interferometer. The system is based on a low-cost Field Programmable Gate Array (FPGA) allowing the integration of several functions in a single portable device. This system is optimal for high speed applications where online measurement is needed and the reconfigurability feature allows the addition of different modules for error compensation, as might be required by a specific application. PMID:22164040

  6. Radiation dose measurement and risk estimation for paediatric patients undergoing micturating cystourethrography.

    Science.gov (United States)

    Sulieman, A; Theodorou, K; Vlychou, M; Topaltzikis, T; Kanavou, D; Fezoulidis, I; Kappas, C

    2007-09-01

    Micturating cystourethrography (MCU) is considered to be the gold-standard method used to detect and grade vesicoureteric reflux (VUR) and show urethral and bladder abnormalities. It accounts for 30-50% of all fluoroscopic examinations in children. Therefore, it is crucial to define and optimize the radiation dose received by a child during MCU examination, taking into account that children have a higher risk of developing radiation-induced cancer than adults. This study aims to quantify and evaluate, by means of thermoluminescence dosimetry (TLD), the radiation dose to the newborn and paediatric populations undergoing MCU using fluoroscopic imaging. Evaluation of entrance surface dose (ESD), organ and surface dose to specific radiosensitive organs was carried out. Furthermore, the surface dose to the co-patient, i.e. individuals helping in the support, care and comfort of the children during the examination, was evaluated in order to estimate the level of risk. 52 patients with mean age of 0.36 years who had undergone MCU using digital fluoroscopy were studied. ESD, surface doses to thyroid, testes/ovaries and co-patients were measured with TLDs. MCU with digital equipment and fluoroscopy-captured image technique can reduce the radiation dose by approximately 50% while still obtaining the necessary diagnostic information. Radiographic exposures were made in cases of the presence of reflux or of the difficulty in evaluating a finding. The radiation surface doses to the thyroid and testes are relatively low, whereas the radiation dose to the co-patient is negligible. The risks associated with MCU for patients and co-patients are negligible. The results of this study provide baseline data to establish reference dose levels for MCU examination in very young patients.

  7. RaD-X: Complementary measurements of dose rates at aviation altitudes

    Science.gov (United States)

    Meier, Matthias M.; Matthiä, Daniel; Forkert, Tomas; Wirtz, Michael; Scheibinger, Markus; Hübel, Robert; Mertens, Christopher J.

    2016-09-01

    The RaD-X stratospheric balloon flight organized by the National Aeronautics and Space Administration was launched from Fort Sumner on 25 September 2015 and carried several instruments to measure the radiation field in the upper atmosphere at the average vertical cutoff rigidity Rc of 4.1 GV. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt) in cooperation with Lufthansa German Airlines supported this campaign with an independent measuring flight at the altitudes of civil aviation on a round trip from Germany to Japan. The goal was to measure dose rates under similar space weather conditions over an area on the Northern Hemisphere opposite to the RaD-X flight. Dose rates were measured in the target areas, i.e., around vertical cutoff rigidity Rc of 4.1 GV, at two flight altitudes for about 1 h at each position with acceptable counting statistics. The analysis of the space weather situation during the flights shows that measuring data were acquired under stable and moderate space weather conditions with a virtually undisturbed magnetosphere. The measured rates of absorbed dose in silicon and ambient dose equivalent complement the data recorded during the balloon flight. The combined measurements provide a set of experimental data suitable for validating and improving numerical models for the calculation of radiation exposure at aviation altitudes.

  8. Measurement of photoneutron dose produced by wedge filters of a high energy linac using polycarbonate films.

    Science.gov (United States)

    Hashemi, Seyed Mehdi; Hashemi-Malayeri, Bijan; Raisali, Gholamreza; Shokrani, Parvaneh; Sharafi, Ali Akbar; Torkzadeh, Falamarz

    2008-05-01

    Radiotherapy represents the most widely spread technique to control and treat cancer. To increase the treatment efficiency, high energy linacs are used. However, applying high energy photon beams leads to a non-negligible dose of neutrons contaminating therapeutic beams. In addition, using conventional linacs necessitates applying wedge filters in some clinical conditions. However, there is not enough information on the effect of these filters on the photoneutrons produced. The aim of this study was to investigate the change of photoneutron dose equivalent due to the use of linac wedge filters. A high energy (18 MV) linear accelerator (Elekta SL 75/25) was studied. Polycarbonate films were used to measure the dose equivalent of photoneutrons. After electrochemical etching of the films, the neutron dose equivalent was calculated using Hp(10) factor, and its variation on the patient plane at 0, 5, 10, 50 and 100 cm from the center of the X-ray beam was determined. By increasing the distance from the center of the X-ray beam towards the periphery, the photoneutron dose equivalent decreased rapidly for the open and wedged fields. Increasing of the field size increased the photoneutron dose equivalent. The use of wedge filter increased the proportion of the neutron dose equivalent. The increase can be accounted for by the selective absorption of the high energy photons by the wedge filter.

  9. Neutron dose measurements with the GSI ball at high-energy accelerators.

    Science.gov (United States)

    Fehrenbacher, G; Gutermuth, F; Kozlova, E; Radon, T; Schuetz, R

    2007-01-01

    A moderator-type neutron monitor containing pairs of TLD 600/700 elements (Harshaw) modified with the addition of a lead layer (GSI ball) for the measurement of the ambient dose equivalent from neutrons at medium- and high-energy accelerators, is introduced in this work. Measurements were performed with the Gesellschaft für Schwerionenforschung (GSI) ball as well as with conventional polyethylene (PE) spheres at the high-energy accelerator SPS at European Organization for Nuclear Research [CERN (CERF)] and in Cave A of the heavy-ion synchrotron SIS at GSI. The measured dose values are compared with dose values derived from calculated neutron spectra folded with dose conversion coefficients. The estimated reading of the spheres calculated by means of the response functions and the neutron spectra is also included in the comparison. The analysis of the measurements shows that the PE/Pb sphere gives an improved estimate on the ambient dose equivalent of the neutron radiation transmitted through shielding of medium- and high-energy accelerators.

  10. Long-term dose measurements applying a human anthropomorphic phantom onboard an aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Berger, T. [DLR-German Aerospace Center, Institute for Aerospace Medicine, Radiation Biology, Linder Hoehe, DE-51147 Cologne (Germany)], E-mail: thomas.berger@dlr.de; Meier, M.; Reitz, G. [DLR-German Aerospace Center, Institute for Aerospace Medicine, Radiation Biology, Linder Hoehe, DE-51147 Cologne (Germany); Schridde, M. [Lufthansa Cargo AG, DE-65441 Kelsterbach (Germany)

    2008-02-15

    The exposure of aircrew personnel to cosmic radiation has been considered as occupational exposure in the European Union since the European Council Directive 96/26/EURATOM became effective on 13th May 1996. In Germany the corresponding safety standards for aircrew are regulated by the German Radiation Protection Ordinance, which implemented the European law in 2001. The radiation exposure of the flight crew of the LUFTHANSA group is calculated by the DLR Institute of Aerospace Medicine in Cologne, applying the calculation program EPCARD in the framework of the aircrew dose determination system CALculated and Verified Aviation DOSimetry (CALVADOS). Besides the operational dose calculations, DLR performs measurements at airflight altitudes using active (e.g. TEPC, DOSTEL, etc.) and passive (Thermoluminescence detectors (TLDs), bubble detectors) radiation detectors to verify the calculation codes. Within these activities the project BOdy DOsimetry (BODO) comprised a long-term exposure of a RANDO anthropomorphic phantom to measure the skin and the depth dose distribution inside a human torso applying TLDs at aviation altitudes for the first time. The torso was flown onboard a LUFTHANSA Cargo aircraft for 3 months from mid of July to mid of October 2004. Over 800 TLDs were positioned for depth dose measurements in the head, the thorax and the abdomen of the torso. In addition dosemeter packages have been distributed on the surface of the torso to measure the skin dose as well as in the transport container and on the flight deck.

  11. Performances of Dose Measurement of Commercial Electronic Dosimeters using Geiger Muller Tube and PIN Diode

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hyunjun; Kim, Chankyu; Kim, Yewon; Kim, Giyoon; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    There are two categories in personal dosimeters, one is passive type dosimeter such as TLD (thermoluminescence dosimeter) and the other is active type dosimeter such as electronic dosimeter can show radiation dose immediately while TLD needs long time to readout its data by heating process. For improving the reliability of measuring dose for any energy of radiations, electronic dosimeter uses energy filter by metal packaging its detector using aluminum or copper, but measured dose of electronic dosimeter with energy filter cannot be completely compensated in wide radiation energy region. So, in this paper, we confirmed the accuracy of dose measurement of two types of commercial EPDs using Geiger Muller tube and PIN diode with CsI(Tl) scintillator in three different energy of radiation field. The experiment results for Cs-137 was almost similar with calculation value in the results of both electronic dosimeters, but, the other experiment values with Na-22 and Co-60 had higher error comparing with Cs-137. These results were caused by optimization of their energy filters. The optimization was depending on its thickness of energy filter. So, the electronic dosimeters have to optimizing the energy filter for increasing the accuracy of dose measurement or the electronic dosimeter using PIN diode with CsI(Tl) scintillator uses the multi-channel discriminator for using its energy information.

  12. [Dose response curve of paclitaxel measured by histoculture drug response assay].

    Science.gov (United States)

    Yoshimasu, Tatsuya; Oura, Shoji; Hirai, Issei; Kokawa, Yozo; Okamura, Yoshitaka; Furukawa, Tomoko

    2005-04-01

    Dose response curves of paclitaxel were measured by histoculture drug response assay (HDRA) in 11 lung cancer patients. Inhibition rates of paclitaxel at several concentrations were measured and fitted to the sigmoid dose response curve, using non-linear least square analysis, with fitting equation y=A (1-1/(1+exp (b (x-log (ED50)). Parameters A, b, and ED50 were 88.3+/-6.0 (80.0-100.0) %, 9.57+/-4.32 (2.25-15.0), and 26.8+/-8.1 (15.0-41.0) microg/ml, respectively. The parameter b was lower in well-differentiated tumors compared with moderately and poorly-differentiated tumors. Dose response curves of paclitaxel could be measured by HDRA in lung cancer. This method provides us more information for drug sensitivity than the usual HDRA method. This may lead to the improved accuracy of HDRA.

  13. Gamma Radiation Measurements and Dose Rates in Commonly Used Building Materials in Cyprus

    CERN Document Server

    Michael, F; Parpottas, Y

    2010-01-01

    A first comprehensive study is presented on radioactivity concentrations and dose rates in 87 commonly used materials, manufactured or imported in Cyprus, for building purposes. The natural radioactivity of K-40, Th-232, U-238 and Ra-226 is determined using high-resolution gamma ray spectroscopy. The respective dose rates and the associated radiological effect indices are also calculated. A comparison of the measured specific activity values with the corresponding world average values shows that most of them are below the world average activity values. The annual indoor effective dose rates received by an individual from three measured imported granites and four measured imported ceramics are found to be higher than the world upper limit value of 1 mSv y-1. Hence, these materials should have a restricted use according to their corresponding calculated activity concentration index values and the related EC 1999 guidelines.

  14. On-line adaptive line frequency noise cancellation from a nuclear power measuring channel

    Directory of Open Access Journals (Sweden)

    Qadir Javed

    2011-01-01

    Full Text Available On-line software for adaptively canceling 50 Hz line frequency noise has been designed and tested at Pakistan Research Reactor 1. Line frequency noise causes much problem in weak signals acquisition. Sometimes this noise is so dominant that original signal is totally corrupted. Although notch filter can be used for eliminating this noise, but if signal of interest is in close vicinity of 50 Hz, then original signal is also attenuated and hence overall performance is degraded. Adaptive noise removal is a technique which could be employed for removing line frequency without degrading the desired signal. In this paper line frequency noise has been eliminated on-line from a nuclear power measuring channel. The adaptive LMS algorithm has been used to cancel 50 Hz noise. The algorithm has been implemented in labVIEW with NI 6024 data acquisition card. The quality of the acquired signal has been improved much as can be seen in experimental results.

  15. An instrument for online measurement of structural orientation in translucent polymer sheets

    Indian Academy of Sciences (India)

    P K Palanisamy; D Mangaiyarkarasi; A Ramalingam

    2000-02-01

    In many applications of polymer materials, a high tensile strength is required. There is a definite correlation between the degree of orientation of molecular chains achieved in the orientation process and the tensile strength obtained. In this work, we describe design and fabrication details of a device, `Laser based polymer orientation grader’, for online measurement of the degree of orientation to obtain a high consistent tensile strength as output. This instrument has been designed making skilful use of the optical anisotropic property of the oriented polymer strip. The principle is based on the fact that the spatial distribution of laser light passing through the translucent polymer sheet depends on the degree of orientation of long chain molecules in the sheet. The method has potential online application in monitoring and controlling of anisotropy in manufacturing processes.

  16. Dose and Position Measurements using a Novel Four-Dimensional In Vivo Dosimetry System

    Science.gov (United States)

    Cherpak, Amanda

    This work presents a comprehensive characterization of the dosimetric and position measurement characteristics as well as clinical implementation of a novel four-dimensional in vivo dosimetry system, RADPOS. Preliminary dose and position measurements were first conducted to evaluate any deviation from known characteristics of metal-oxide semiconductor field-effect transistors, MOSFETs, and electromagnetic positioning systems when they are used alone. The system was then combined with a deformable tissue equivalent lung phantom to simulate respiratory-induced tumour motion and lung deformation and to evaluate the potential use of the system as an effective quality assurance tool for 4D conformal radiotherapy. The final phase of testing involved using the RADPOS 4D in vivo dosimetry system in two different clinical trials. The first involved characterizing the breathing patterns of lung cancer patients throughout the course of treatment and measuring inter-fraction variations in skin dose. Within this framework, the feasibility of general use of the RADPOS system on patients during daily treatment fractions was also assessed. The second trial involved a modified RADPOS detector that contained a MOSFET array, allowing for dose measurements at five different points. This detector was used to measure dose and position in the prostatic urethra throughout seed implantation for transperineal interstitial permanent prostate brachytherapy. It has been found that the dosimetric response is similar to that of a microMOSFET, when used alone, aside from a slightly higher variation in angular response. Position measurements can be obtained with an uncertainty of +/- 2 mm when the detector remains within a specific optimal volume with respect to the magnetic field transmitter and when interfering metal objects are kept at least 200 mm away. Combining the RADPOS system with a deformable lung equivalent phantom allowed for efficient quality assurance of 4D radiation therapy, as

  17. A Comparison of Multiscale Permutation Entropy Measures in On-Line Depth of Anesthesia Monitoring

    Science.gov (United States)

    Li, Xiaoli; Li, Duan; Li, Yongwang; Ursino, Mauro

    2016-01-01

    Objective Multiscale permutation entropy (MSPE) is becoming an interesting tool to explore neurophysiological mechanisms in recent years. In this study, six MSPE measures were proposed for on-line depth of anesthesia (DoA) monitoring to quantify the anesthetic effect on the real-time EEG recordings. The performance of these measures in describing the transient characters of simulated neural populations and clinical anesthesia EEG were evaluated and compared. Methods Six MSPE algorithms—derived from Shannon permutation entropy (SPE), Renyi permutation entropy (RPE) and Tsallis permutation entropy (TPE) combined with the decomposition procedures of coarse-graining (CG) method and moving average (MA) analysis—were studied. A thalamo-cortical neural mass model (TCNMM) was used to generate noise-free EEG under anesthesia to quantitatively assess the robustness of each MSPE measure against noise. Then, the clinical anesthesia EEG recordings from 20 patients were analyzed with these measures. To validate their effectiveness, the ability of six measures were compared in terms of tracking the dynamical changes in EEG data and the performance in state discrimination. The Pearson correlation coefficient (R) was used to assess the relationship among MSPE measures. Results CG-based MSPEs failed in on-line DoA monitoring at multiscale analysis. In on-line EEG analysis, the MA-based MSPE measures at 5 decomposed scales could track the transient changes of EEG recordings and statistically distinguish the awake state, unconsciousness and recovery of consciousness (RoC) state significantly. Compared to single-scale SPE and RPE, MSPEs had better anti-noise ability and MA-RPE at scale 5 performed best in this aspect. MA-TPE outperformed other measures with faster tracking speed of the loss of unconsciousness. Conclusions MA-based multiscale permutation entropies have the potential for on-line anesthesia EEG analysis with its simple computation and sensitivity to drug effect

  18. Online Vce measurement method for wear-out monitoring of high power IGBT modules

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Ghimire, Pramod; de Vega, Angel Ruiz

    2013-01-01

    A simple Vce online monitoring circuit is presented in this paper. It allows an accurate wear out prediction of IGBT modules, in high-power applications, during normal converter operation. Bipolar measurement allows monitoring of both IGBT and antiparallel diode. The circuit uses two serial...... connected diodes to sense the Vce voltage with millivolt accuracy. One diode acts as a protection to block high DC voltage present on input terminals. When the device is conducting the voltage on the second diode is measured to compensate for the voltage drop on the protection diode thus eliminating voltage...

  19. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations.

    Science.gov (United States)

    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-03-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9%. The dose reductions due to the bismuth shielding were 1.2-55% depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 - 46% for head and 41 - 55% for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2-3%.

  20. Comparison of commercial thermoluminescent readers regarding high-dose high-temperature measurements

    CERN Document Server

    Bilski, P; Obryk, B; Hodyr, K

    2014-01-01

    Three different thermoluminescent measuring systems have been compared with respect to the differences in temperature profiles, spectral sensitivities, as well as linearity of dose response characteristics. The comparison was performed using the Harshaw 3500, Riso DA-20 and RA94 TLD readers. The instruments were tested for the readouts of highly irradiated LiF:Mg,Cu,P (MCP) TL detectors, which require readout up to 550 C, in case of doses exceeding 1 kGy. It was found that the Harshaw 3500 can be used, without any additional light attenuation, for the measurements of MCP detectors exposed to doses up to about 5 Gy. For the other two readers the upper dose limit is about 5 times lower. It was also found that the Harshaw 3500 shows the best thermal stability considering the peak maximum position. For the ultra-high doses the differences in the spectral characteristics of the applied optical filters and photomultipliers, in conjunction with an evolution of the MCP TL emission spectrum with increasing dose, signi...

  1. Gamma irradiator dose mapping: a Monte Carlo simulation and experimental measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Rogerio R.; Ribeiro, Mariana A.; Grynberg, Suely E.; Ferreira, Andrea V.; Meira-Belo, Luiz Claudio, E-mail: rrr@cdtn.b, E-mail: marianaalmeida@ufmg.b, E-mail: seg@cdtn.b, E-mail: avf@cdtn.b, E-mail: lcmb@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Sousa, Romulo V.; Sebastiao, Rita de C.O., E-mail: romuloverdolin@yahoo.com.b, E-mail: ritacos@ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Quimica

    2009-07-01

    Gamma irradiator facilities can be used in a wide range of applications such as biological and chemical researches, food treatment and sterilization of medical devices and products. Dose mapping must be performed in these equipment in order to establish plant operational parameters, as dose uniformity, source utilization efficiency and maximum and minimum dose positions. The isodoses curves are generally measured using dosimeters distributed throughout the device, and this procedure often consume a large amount of dosimeters, irradiation time and manpower. However, a detailed curve doses identification of the irradiation facility can be performed using Monte Carlo simulation, which reduces significantly the monitoring with dosimeters. The present work evaluates the absorbed dose in the CDTN/CNEN Gammacell Irradiation Facility, using the Monte Carlo N-particles (MCNP) code. The Gammacell 220, serial number 39, was produced by Atomic Energy of Canada Limited and was loaded with sources of {sup 60}Co. Dose measurements using TLD and Fricke dosimeters were also performed to validate the calculations. The good agreement of the results shows that Monte Carlo simulations can be used as a predictive tool of irradiation planning for the CDTN/CNEN Gamma Cell Irradiator. (author)

  2. Effective dose measured with a life size human phantom in a low Earth orbit mission.

    Science.gov (United States)

    Yasuda, Hiroshi

    2009-03-01

    The biggest concern about the health risk to astronauts is how large the stochastic effects (cancers and hereditary effects) of space radiation could be. The practical goal is to determine the "effective dose" precisely, which is difficult for each crew because of the complex transport processes of energetic secondary particles. The author and his colleagues thus attempted to measure an effective dose in space using a life-size human phantom torso in the STS-91 Shuttle-Mir mission, which flew at nearly the same orbit as that of the International Space Station (ISS). The effective dose for about 10-days flight was 4.1 mSv, which is about 90% of the dose equivalent (H) at the skin; the lowest H values were seen in deep, radiation-sensitive organs/tissues such as the bone marrow and colon. Succeeding measurements and model calculations show that the organ dose equivalents and effective dose in the low Earth orbit mission are highly consistent, despite the different dosimetry methodologies used to determine them.

  3. Study on an On-line Measurement System of Corrosion Rate by Linear Polarization Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Jeon Soo; Lee, Jae Kun; Lee, Jae Bong; Park, Pyl Yang [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2012-04-15

    The linear polarization resistance method is one of the widely used techniques for the corrosion rate monitoring in the water circulating systems of plants. The measurement is simple and rapid, so that a continuous on-line monitoring is possible without any shutdown of plants. A 2-electrode polarization corrosion rate measurement system was installed in a laboratory using a data acquisition board and PC. The signal processing parameters were optimized for the accurate corrosion rate measurement, and the polarization resistance was compensated with the solution resistance measured by the high frequency sine wave signal of an output channel. The precision of corrosion rate data was greatly improved by removing the initial noise signals on measuring the polarization resistance.

  4. High stability interleaved fiber Michelson interferometer for on-line precision displacement measurements

    Science.gov (United States)

    Xie, Fang; Chen, Xianfeng; Zhang, Lin

    2009-11-01

    A self-reference fiber Michelson interferometer measurement system, which employs fiber Bragg gratings (FBGs) as in-fiber reflective mirrors and interleaves together two fiber Michelson interferometers that share the common-interferometric-optical path, is presented. One of the fiber interferometers is used to stabilise the system by the use of an electronic feedback loop to compensate the influences resulting from the environmental disturbances, while the other one is used to perform the measurement task. The influences resulting from the environmental disturbances have been eliminated by the compensating action of the electronic feedback loop, this makes the system suitable for on-line precision measurement. By means of the homodyne phase-tracking technique, the linearity of the measurement results of displacement measurements has been very high.

  5. In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Da; Padole, Atul; Li, Xinhua; Singh, Sarabjeet; Khawaja, Ranish Deedar Ali; Lira, Diego; Shi, Jim Q.; Otrakji, Alexi; Kalra, Mannudeep K.; Liu, Bob, E-mail: bliu7@mgh.harvard.edu [Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Liu, Tianyu; Xu, X. George [Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2014-09-15

    Purpose: To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Methods: Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin doses were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. Results: The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8% − 25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2 ± 3.3 and 16.5 ± 2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling

  6. Online measurements of non-organic components in flue gas; Online-maetning av oorganiska komponenter i roekgas

    Energy Technology Data Exchange (ETDEWEB)

    Niklasson, Fredrik; Claesson, Frida; Haraldsson, Conny

    2010-03-15

    an ICP-MS instrument can be used for on-line measurements of the concentrations of alkali metals in a flue gas, although further work should be addressed the design of the gas sampling line to avoid clogging by tar and fly ash particles

  7. A scintillating gas detector for 2D dose measurements in clinical carbon beams.

    Science.gov (United States)

    Seravalli, E; de Boer, M; Geurink, F; Huizenga, J; Kreuger, R; Schippers, J M; van Eijk, C W E; Voss, B

    2008-09-07

    A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

  8. On-line dynamic measurement of blood viscosity, hematocrit and change of blood volume

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To develop an on-line system for the measurement of blood viscosity and hematocrit. The dynamic changes of the macrovascular blood volumes,microvascular blood volumes and the total blood volume were observed by means of calculating from the testing result. Methods: Applying traditional viscosity measurement principle and specific wavelength optic density measurement method, an on-line system for the measurement of blood viscosity and hematocrit was developed, and the A/D multifunctionai board and the testing circuit were designed by ourselves. The system was validated by experiments both in vitro and in vivo. Therapeutic effects of hypertonic saline dextran solution (HSD) and Lactatic Ringer's solution at the early stage after burn-blast combined injury were compared by this method. Results: The results showed that the system has attained the goal of the design. The changes of the blood viscosity and hematocrit could be detected effectively and continuously. The changes of macrovascular, microvascular and total blood volume could be calculated approximately. Conclusions: The system and the method can continuously on-line test the blood viscosity and hematocrit, and reveal the change and distribution of blood volumes more accurately and dearly in the therapy process by estimating changes of the macrovascular, microvascular and total blood volumes, respectively. It has confirmed that HSD treatment could increase blood pressure and attenuate tissue edema by significantly increasing total blood volume,improving macrocirculatory and microcirculatory blood volumes. This study suggested that it could be desirable to develop an experiment technique based on the method mentioned above.

  9. Metrological Characterization of an Improved DSP-Based On-line Integrator for Magnetic Measurements at CERN

    CERN Document Server

    Arpaia, P; Spiezia, G

    2007-01-01

    An improved on-line version of the self-calibrating digital instrument for flux measurements on superconductive magnets for particle accelerators, prototyped at the European Organization for Nuclear Research (CERN) in cooperation with the University of Sannio, is proposed. The instrument acquires voltage arising from rotating coils transducers. Then, the samples are online integrated and suitably processed in order to achieve flux analysis time down to 2.0 ìs, with resolution of 50 ns. Details about hardware and firmware conception, on-line measurement principle, and preliminary results of metrological characterization of the prototype are provided.

  10. Measured dose rate constant from oncology patients administered 18F for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, Brian; Holahan, Brian; Aime, Jean; Humm, John; St Germain, Jean; Dauer, Lawrence T. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States) and Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States) and Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10065 (United States)

    2012-10-15

    Purpose: Patient exposure rate measurements verify published patient dose rate data and characterize dose rates near 2-18-fluorodeoxyglucose ({sup 18}F-FDG) patients. A specific dose rate constant based on patient exposure rate measurements is a convenient quantity that can be applied to the desired distance, injection activity, and time postinjection to obtain an accurate calculation of cumulative external radiation dose. This study reports exposure rates measured at various locations near positron emission tomography (PET) {sup 18}F-FDG patients prior to PET scanning. These measurements are normalized for the amount of administered activity, measurement distance, and time postinjection and are compared with other published data. Methods: Exposure rates were measured using a calibrated ionization chamber at various body locations from 152 adult oncology patients postvoid after a mean uptake time of 76 min following injection with a mean activity of 490 MBq {sup 18}F-FDG. Data were obtained at nine measurement locations for each patient: three near the head, four near the chest, and two near the feet. Results: On contact with, 30 cm superior to and 30 cm lateral to the head, the mean (75th percentile) dose rates per unit injected activity at 60 min postinjection were 0.482 (0.511), 0.135 (0.155), and 0.193 (0.223) {mu}Sv/MBq h, respectively. On contact with, 30 cm anterior to, 30 cm lateral to and 1 m anterior to the chest, the mean (75th percentile) dose rates per unit injected activity at 60 min postinjection were 0.623 (0.709), 0.254 (0.283), 0.190 (0.218), and 0.067 (0.081) {mu}Sv/MBq h respectively. 30 cm inferior and 30 cm lateral to the feet, the mean (75th percentile) dose rates per unit injected activity at 60 min postinjection were 0.024 (0.022) and 0.039 (0.044) {mu}Sv/MBq h, respectively. Conclusions: The measurements for this study support the use of 0.092 {mu}Sv m{sup 2}/MBq h as a reasonable representation of the dose rate anterior from the chest of

  11. A recommendation for revised dose calibrator measurement procedures for 89Zr and 124I.

    Directory of Open Access Journals (Sweden)

    Bradley J Beattie

    Full Text Available Because of their chemical properties and multiday half lives, iodine-124 and zirconium-89 are being used in a growing number of PET imaging studies. Some aspects of their quantitation, however, still need attention. For (89Zr the PET images should, in principle, be as quantitatively accurate as similarly reconstructed 18F measurements. We found, however, that images of a 20 cm well calibration phantom containing (89Zr underestimated the activity by approximately 10% relative to a dose calibrator measurement (Capintec CRC-15R using a published calibration setting number of 465. PET images of (124I, in contrast, are complicated by the contribution of decays in cascade that add spurious coincident events to the PET data. When these cascade coincidences are properly accounted for, quantitatively accurate images should be possible. We found, however, that even with this correction we still encountered what appeared to be a large variability in the accuracy of the PET images when compared to dose calibrator measurements made using the calibration setting number, 570, recommended by Capintec. We derive new calibration setting numbers for (89Zr and (124I based on their 511 keV photon peaks as measured on an HPGe detector. The peaks were calibrated relative to an 18F standard, the activity level of which was precisely measured in a dose calibrator under well-defined measurement conditions. When measuring (89Zr on a Capintec CRC-15R we propose the use of calibration setting number 517. And for (124I, we recommend the use of a copper filter surrounding the sample and the use of calibration setting number 494. The new dose calibrator measurement procedures we propose will result in more consistent and accurate radioactivity measurements of (89Zr and (124I. These and other positron emitting radionuclides can be accurately calibrated relative to 18F based on measurements of their 511 keV peaks and knowledge of their relative positron abundances.

  12. Online participation in climate change adaptation: A case study of agricultural adaptation measures in Northern Italy.

    Science.gov (United States)

    Bojovic, Dragana; Bonzanigo, Laura; Giupponi, Carlo; Maziotis, Alexandros

    2015-07-01

    The new EU strategy on adaptation to climate change suggests flexible and participatory approaches. Face-to-face contact, although it involves time-consuming procedures with a limited audience, has often been considered the most effective participatory approach. In recent years, however, there has been an increase in the visibility of different citizens' initiatives in the online world, which strengthens the possibility of greater citizen agency. This paper investigates whether the Internet can ensure efficient public participation with meaningful engagement in climate change adaptation. In elucidating issues regarding climate change adaptation, we developed an eParticipation framework to explore adaptation capacity of agriculture to climate change in Northern Italy. Farmers were mobilised using a pre-existing online network. First they took part in an online questionnaire for revealing their perceptions of and reactions to the impacts of ongoing changes in agriculture. We used these results to suggest a portfolio of policy measures and to set evaluation criteria. Farmers then evaluated these policy options, using a multi criteria analysis tool with a simple user-friendly interface. Our results showed that eParticipation is efficient: it supports a rapid data collection, while involving high number of participants. Moreover, we demonstrated that the digital divide is decreasingly an obstacle for using online spaces for public engagement. This research does not present eParticipation as a panacea. Rather, eParticipation was implemented with well-established participatory approaches to both validate the results and, consequently, communicate meaningful messages on local agricultural adaptation practices to regional decision-makers. Feedbacks from the regional decision-makers showed their interest in using eParticipation to improve communication with farmers in the future. We expect that, with further Internet proliferation, eParticipation may allow the inclusion of

  13. Virtual Sensors for On-line Wheel Wear and Part Roughness Measurement in the Grinding Process

    Directory of Open Access Journals (Sweden)

    Ander Arriandiaga

    2014-05-01

    Full Text Available Grinding is an advanced machining process for the manufacturing of valuable complex and accurate parts for high added value sectors such as aerospace, wind generation, etc. Due to the extremely severe conditions inside grinding machines, critical process variables such as part surface finish or grinding wheel wear cannot be easily and cheaply measured on-line. In this paper a virtual sensor for on-line monitoring of those variables is presented. The sensor is based on the modelling ability of Artificial Neural Networks (ANNs for stochastic and non-linear processes such as grinding; the selected architecture is the Layer-Recurrent neural network. The sensor makes use of the relation between the variables to be measured and power consumption in the wheel spindle, which can be easily measured. A sensor calibration methodology is presented, and the levels of error that can be expected are discussed. Validation of the new sensor is carried out by comparing the sensor’s results with actual measurements carried out in an industrial grinding machine. Results show excellent estimation performance for both wheel wear and surface roughness. In the case of wheel wear, the absolute error is within the range of microns (average value 32 μm. In the case of surface finish, the absolute error is well below Ra 1 μm (average value 0.32 μm. The present approach can be easily generalized to other grinding operations.

  14. Development of an on-line measuring and monitoring system for fouling based on Delphi

    Science.gov (United States)

    Wang, Yuanyuan; Wang, Jianguo

    2010-12-01

    The presence of fouling reduced the heat transfer capability of heat transfer equipments and increased the flow resistance of the medium. Thus the resulting series of economic losses received worldwide attention of the relevant heat transfer industry and countries. For the heating system fouling, direct measurement is nearly impossible. And it is extremely difficulty of structuring mathematic model. Although there are existing monitoring methods, results are not satisfactory. This paper intends to develop a new on-line measuring and monitoring system for heating system fouling. The operating theory of this on-line measuring and monitoring system is based on the soft-sensor technology and Expert System. We select some easily measurements as primary variables, such as pressures, flow rates and temperatures. Through some algorithms, we obtained dozens of secondary variables, for example, the coefficient of flow resistance, the efficiency and cost of heating system and so on. Based on these variables, we construct the knowledge base of this System. This system mainly uses Delphi and Excel as development tools. Now, the system is running well in some heating station, and has reached the expecting result.

  15. Online measurement of LHC beam parameters with the ATLAS High Level Trigger

    CERN Document Server

    Strauss, E; The ATLAS collaboration

    2011-01-01

    We present an online measurement of the LHC beam parameters in ATLAS using the High Level Trigger (HLT). When a significant change is detected in the measured beamspot, it is distributed to the HLT. There, trigger algorithms like b-tagging which calculate impact parameters or decay lengths benefit from a precise,up-to-date set of beamspot parameters. Additionally, online feedback is sent to the LHC operators in real time. The measurement is performed by an algorithm running on the Level 2 trigger farm, leveraging the high rate of usable events. Dedicated algorithms perform a full scan of the silicon detector to reconstruct event vertices from registered tracks. The distribution of these vertices is aggregated across the farm and their shape is extracted through fits every 60 seconds to determine the beamspot position, size, and tilt. The reconstructed beam values are corrected for detector resolution effects, measured in situ using the separation of vertices whose tracks have been split into two collections. ...

  16. Online Measurement of LHC Beam Parameters with the ATLAS High Level Trigger

    CERN Document Server

    Strauss, E; The ATLAS collaboration

    2011-01-01

    We present an online measurement of the LHC beam parameters in ATLAS using the High Level Trigger (HLT). When a significant change is detected in the measured beamspot, it is distributed to the HLT. There, trigger algorithms like b-tagging which calculate impact parameters or decay lengths benefit from a precise, up-to-date set of beamspot parameters. Additionally, online feedback is sent to the LHC operators in real time. The measurement is performed by an algorithm running on the Level 2 trigger farm, leveraging the high rate of usable events. Dedicated algorithms perform a full scan of the silicon detector to reconstruct event vertices from registered tracks. The distribution of these vertices is aggregated across the farm and their shape is extracted through fits every 60 seconds to determine the beamspot position, size, and tilt. The reconstructed beam values are corrected for detector resolution effects, measured in situ using the separation of vertices whose tracks have been split into two collections....

  17. Dose measurement in periapical radiographic exams using dosemeter pen: a look at the radioprotection

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Renato; Ferreira, Vanessa, E-mail: vanessamachado@ufmg.br [Curso Superior de Tecnologia em Radiologia. Faculdade de Medicina. Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Pereira, Claubia; Oliveira, Arno H.; Veloso, M.A.F., E-mail: gbarros@nuclear.ufmg.br, E-mail: claubia@nuclear.ufmg.br, E-mail: heeren@nuclear.ufmg.br, E-mail: Dora@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2011-07-01

    The use of radiology has been a large increase with the crescent accessibility to dental care, orthodontics and aesthetic. Besides the increase in the number of exams, there was an increase in radiation dose during dental exams such as computed tomography. The objective of this work is to evaluate the radiation dose to which the patient is subjected in a peri apical dental radiography. The dose values were measured with a dosimeter pen during radiographs in real exams peri apical with the X-ray equipment Timex 70 C Gnatus. During the exams realization, was maintained, in the holder, the dosimeter pen near to the region of interest. The values collected were recorded in dosimeter pen. These values were compared with the reference doses of the Portaria 453 of ANVISA, this procedure allows to verify if the recommended dose limits for this exam are being respected. These data indicates if the used equipment is calibrated and in good condition of use. It was performed a comparison between the obtained experimental dose values and the values found from computer simulation with the code MCNPX 2.6.0. (author)

  18. Measurement of a wide-range of X-ray doses using specialty doped silica fibres

    Science.gov (United States)

    Abdul Sani, S. F.; Hammond, R.; Jafari, S. M.; Wahab, Norfadira; Amouzad Mahdiraji, G.; Siti Shafiqah, A. S.; Abdul Rashid, H. A.; Maah, M. J.; Aldousari, H.; Alkhorayef, M.; Alzimami, M.; Bradley, D. A.

    2017-08-01

    Using six types of tailor-made doped optical fibres, we carry out thermoluminescent (TL) studies of X-rays, investigating the TL yield for doses from 20 mGy through to 50 Gy. Dosimetric parameters were investigated for nominal 8 wt% Ge doped fibres that in two cases were co-doped, using B in one case and Br in the other. A comparative measurement of surface analysis has also been made for non-annealed and annealed capillary fibres, use being made of X-ray Photoelectron Spectroscopy (XPS) analysis. Comparison was made with the conventional TL phosphor LiF in the form of the proprietary product TLD-100, including dose response and glow curves investigated for X-rays generated at 60 kVp over a dose range from 2 cGy to 50 Gy. The energy response of the fibres was also performed for X-rays generated at peak accelerating potentials of 80 kVp, 140 kVp, 250 kVp and 6 MV photons for an absorbed dose of 2 Gy. Present results show the samples to be suitable for use as TL dosimeters, with good linearity of response and a simple glow curve (simple trap) distribution. It has been established that the TL performance of an irradiated fibre is not only influenced by radiation parameters such as energy, dose-rate and total dose but also the type of fibre.

  19. Research and application of online measurement system of tire tread profile in automobile tire production

    Science.gov (United States)

    Wang, Pengyao; Chen, Xiangguang; Yang, Kai; Liu, Xuejiao

    2017-01-01

    To improve the measuring efficiency of width and thickness of tire tread in the process of automobile tire production, the actual condition for the tire production process is analyzed, and a fast online measurement system based on moving tire tread of tire specifications is established in this paper. The coordinate data of tire tread profile is acquired by 3D laser sensor, and we use C# language for programming which is an object-oriented programming language to complete the development of client program. The system with laser sensor can provide real-time display of tire tread profile and the data to require in the process of tire production. Experimental results demonstrate that the measuring precision of the system is <= 1mm, it can meet the measurement requirements of the production process, and the system has the characteristics of convenient installation and testing, system stable operation.

  20. Effect of translational and rotational errors on complex dose distributions with off-line and on-line position verification

    NARCIS (Netherlands)

    I.M. Lips; U.A. van der Heide; A.N.T.J. Kotte; M. van Vulpen; A. Bel

    2009-01-01

    PURPOSE: To investigate the influence of translational and rotational errors on prostate intensity-modulated radiotherapy (IMRT) with an integrated boost to the tumor and to evaluate the effect of the use of an on-line correction protocol. METHODS AND MATERIALS: For 19 patients, who had been treated

  1. Measurement of eye lens dose for Varian On-Board Imaging with different cone-beam computed tomography acquisition techniques.

    Science.gov (United States)

    Deshpande, Sudesh; Dhote, Deepak; Thakur, Kalpna; Pawar, Amol; Kumar, Rajesh; Kumar, Munish; Kulkarni, M S; Sharma, S D; Kannan, V

    2016-01-01

    The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT) acquisition protocols of Varian's On-Board Imaging (OBI) system using optically stimulated luminescence dosimeter (OSLD) and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was placed on the patient between the eyebrows of both eyes in line of nose during CBCT image acquisition to measure eye lens doses. The eye lens dose measurements were carried out for three different cone-beam acquisition protocols (standard dose head, low-dose head [LDH], and high-quality head [HQH]) of Varian OBI. Measured doses were correlated with patient geometry and distance between isocenter and eye lens. Measured eye lens doses for standard head and HQH protocols were in the range of 1.8-3.2 mGy and 4.5-9.9 mGy, respectively. However, the measured eye lens dose for the LDH protocol was in the range of 0.3-0.7 mGy. The measured data indicate that eye lens dose to patient depends on the selected imaging protocol. It was also observed that eye lens dose does not depend on patient geometry but strongly depends on distance between eye lens and treatment field isocenter. However, undoubted advantages of imaging system should not be counterbalanced by inappropriate selection of imaging protocol, especially for very intense imaging protocol.

  2. Hepatic CT perfusion measurements: A feasibility study for radiation dose reduction using new image reconstruction method

    Energy Technology Data Exchange (ETDEWEB)

    Negi, Noriyuki, E-mail: noriyuki@med.kobe-u.ac.jp [Division of Radiology, Kobe University Hospital, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Yoshikawa, Takeshi, E-mail: yoshikawa0816@aol.com [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Ohno, Yoshiharu, E-mail: yosirad@kobe-u.ac.jp [Division of Radiology, Kobe University Hospital, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Somiya, Yuichiro, E-mail: somiya13@med.kobe-u.ac.jp [Division of Radiology, Kobe University Hospital, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Sekitani, Toshinori, E-mail: atieinks-toshi@nifty.com [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Sugihara, Naoki, E-mail: naoki.sugihara@toshiba.co.jp [Toshiba Medical Systems Co., 1385 Shimoishigami, Otawara 324-0036 (Japan); Koyama, Hisanobu, E-mail: hkoyama@med.kobe-u.ac.jp [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Kanda, Tomonori, E-mail: k_a@hotmail.co.jp [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Kanata, Naoki, E-mail: takikina12345@yahoo.co.jp [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Murakami, Tohru, E-mail: mura@med.kobe-u.ac.jp [Division of Radiology, Kobe University Hospital, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Kawamitsu, Hideaki, E-mail: kawamitu@med.kobe-u.ac.jp [Division of Radiology, Kobe University Hospital, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan); Sugimura, Kazuro, E-mail: sugimura@med.kobe-u.ac.jp [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuoku, Kobe 650-0017 (Japan)

    2012-11-15

    Objectives: To assess the effects of image reconstruction method on hepatic CT perfusion (CTP) values using two CT protocols with different radiation doses. Materials and methods: Sixty patients underwent hepatic CTP and were randomly divided into two groups. Tube currents of 210 or 250 mA were used for the standard dose group and 120 or 140 mA for the low dose group. The higher currents were selected for large patients. Demographic features of the groups were compared. CT images were reconstructed by using filtered back projection (FBP), image filter (quantum de-noising, QDS), and adaptive iterative dose reduction (AIDR). Hepatic arterial and portal perfusion (HAP and HPP, ml/min/100 ml) and arterial perfusion fraction (APF, %) were calculated using the dual-input maximum slope method. ROIs were placed on each hepatic segment. Perfusion and Hounsfield unit (HU) values, and image noises (standard deviations of HU value, SD) were measured and compared between the groups and among the methods. Results: There were no significant differences in the demographic features of the groups, nor were there any significant differences in mean perfusion and HU values for either the groups or the image reconstruction methods. Mean SDs of each of the image reconstruction methods were significantly lower (p < 0.0001) for the standard dose group than the low dose group, while mean SDs for AIDR were significantly lower than those for FBP for both groups (p = 0.0006 and 0.013). Radiation dose reductions were approximately 45%. Conclusions: Image reconstruction method did not affect hepatic perfusion values calculated by dual-input maximum slope method with or without radiation dose reductions. AIDR significantly reduced images noises.

  3. Low-dose midazolam sedation: an option for patients undergoing serial hepatic venous pressure measurements.

    Science.gov (United States)

    Steinlauf, A F; Garcia-Tsao, G; Zakko, M F; Dickey, K; Gupta, T; Groszmann, R J

    1999-04-01

    The hepatic venous pressure gradient (HVPG) is becoming increasingly used clinically. It is useful in the differential diagnosis of portal hypertension and provides a prognostic index in cirrhotic patients. Performance of serial measurements has been shown to be useful in guiding pharmacological therapy of portal hypertension and variceal hemorrhage. The technique is safe to perform; however, many patients are anxious and reluctant to undergo serial measurements. The effects of sedatives on portal pressure measurements have not yet been defined. The objective of this study was to evaluate the effects of midazolam on the HVPG. Twenty patients with compensated cirrhosis were included in this prospective, double-blind study. The HVPG was determined by subtracting the free hepatic venous pressure (FHVP) from the wedged hepatic venous pressure (WHVP). Patients were randomized to receive either placebo, 0.02 mg/kg midazolam, or 0.03 mg/kg midazolam, administered intravenously over 3 minutes. Immediately after drug administration and every 3 minutes thereafter, for a total of 30 or 40 minutes, measurements were repeated. Three hours later, patients were asked to state whether the sedative affected their state of comfort/relaxation. The effects of both doses of midazolam on HVPG did not differ significantly from those of placebo. Furthermore, neither dose of midazolam induced significant changes in HVPG as compared with baseline values. However, higher-dose midazolam (0.03 mg/kg) was associated with significant reductions in FHVP from baseline and a tendency for a reduction in WHVP. Both doses significantly increased patient comfort and relaxation during the test. Midazolam, used at a dose of 0.02 mg/kg, is effective in increasing patient comfort and relaxation during hepatic venous pressure measurements, without significantly affecting pressures (HVPG, WHVP, or FHVP). It is therefore an acceptable option for patients undergoing serial hepatic venous pressure measurements.

  4. Measurement of Thyroid Dose by TLD arising from Radiotherapy of Breast Cancer Patients from Supraclavicular Field

    Directory of Open Access Journals (Sweden)

    Farhood B.

    2016-06-01

    Full Text Available Background: Breast cancer is the most frequently diagnosed cancer and the leading global cause of cancer death among women worldwide. Radiotherapy plays a significant role in treatment of breast cancer and reduces locoregional recurrence and eventually improves survival. The treatment fields applied for breast cancer treatment include: tangential, axillary, supraclavicular and internal mammary fields. Objective: In the present study, due to the presence of sensitive organ such as thyroid inside the supraclavicular field, thyroid dose and its effective factors were investigated. Materials and Methods: Thyroid dose of 31 female patients of breast cancer with involved supraclavicular lymph nodes which had undergone radiotherapy were measured. For each patient, three TLD-100 chips were placed on their thyroid gland surface, and thyroid doses of patients were measured. The variables of the study include shield shape, the time of patient’s setup, the technologists’ experience and qualification. Finally, the results were analyzed by ANOVA test using SPSS 11.5 software. Results: The average age of the patients was 46±10 years. The average of thyroid dose of the patients was 140±45 mGy (ranged 288.2 and 80.8 in single fraction. There was a significant relationship between the thyroid dose and shield shape. There was also a significant relationship between the thyroid dose and the patient’s setup time. Conclusion: Beside organ at risk such as thyroid which is in the supraclavicular field, thyroid dose possibility should be reduced. For solving this problem, an appropriate shield shape, the appropriate time of the patient’s setup, etc. could be considered.

  5. Dose measurements in pediatric radiology in state of Sergipe, BR; Medidas de dose em radiologia pediatrica no Estado de Sergipe, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, J.P.A.; Magalhaes, C.M.S.; Souza, D.N. [Universidade Federal de Sergipe, Aracaju, SE (Brazil). Dept. de Fisica

    2004-07-01

    Dose measurements are acknowledged to be a vital part of the quality assurance process in diagnostic radiology, and the use of thermoluminescent dosimeters (TLD) is a recommended method of entrance dose quantification. Measurement of doses in radiographic examinations is widely adopted in clinical practice for adults as well as for children. Phantoms can be used to simulate different parts of the body, depending on the materials used to build them. In this work three different sets of phantoms have been prepared with acrylic blocks to simulate thorax children of different ages. The dosimetric measurements have been carried out using TLD and an ionising chamber. Measurements were realised in two X-rays equipment in Aracaju, Brazil. The entrance, half depth and exit surface doses were analysed. (author)

  6. Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms

    NARCIS (Netherlands)

    Koivisto, J.H.; Wolff, J.E.; Kiljunen, T.; Schulze, D.; Kortesniemi, M.

    2015-01-01

    The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the t

  7. Measurement of the primary and scatter dose in high energy photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Van der Linden, P.M. [Catharina Ziekenhuis, Eindhoven (Netherlands). Radiotherapy Dept.; Tiourina, T.B.; Dries, W.

    1995-12-01

    A method is presented to measure the primary and scatter components separately in a water tank using a small cylindrical absorber. Results from this experiment are compared with Monte Carlo calculations. The measurement setup consists of a small cylindrical absorber placed on a central axis of the beam a few centimetres above the radiation detector. Both absorber and detector move along the central axis while absorbed dose is registered. As the primary radiation is fully blocked, only scatter component is measured when a cylindrical absorber is used. Measurements in open fields result in the total absorbed dose being the sum of primary and scatter components. The primary dose component can be derived by substraction. Absorbers with different diameters are used. With decreasing dimensions the relative contribution of the dose due to scatter radiation increases. A steep increase is observed when the range of laterally scattered electrons becomes comparable with the radius of the absorber. Two different Monte Carlo simulations have been performed: with and without secondary electron transport. The data obtained for the former case perfectly agrees with the experiment. The situation where the secondary electron is assumed zero (i.e. local energy deposition) simulates the Cunningham model. Our results show that the Cunningham model predicts lower scatter component under the block edge which can be important for these applications.

  8. Measurements of the electron dose distribution near inhomogeneities using a plastic scintillation detector

    Energy Technology Data Exchange (ETDEWEB)

    Wells, C.M.M.; Mackie, T.R.; Podgorsak, M.B.; Holmes, M.A.; Papanikolaou, N.; Reckwerdt, P.J. [Univ. of Wisconsin, Madison, WI (United States); Cygler, J. [Ottawa Regional Cancer Center, Ontario (Canada); Rogers, D.W.O.; Bielajew, A.F. [National Research Council of Canada, Ottawa, Ontario (Canada); Schmidt, D.G. [Radiation Measurements, Inc., Middleton, WI (United States)] [and others

    1994-07-30

    Accurate measurement of the electron dose distribution near an inhomogeneity is difficult with traditional dosimeters which themselves perturb the electron field. The authors tested the performance of a new high resolution, water-equivalent plastic scintillation detector which has ideal properties for this application. A plastic scintillation detector with a 1 mm diameter, 3 mm long cylindrical sensitive volume was used to measure the dose distributions behind standard benchmark inhomogeneities in water phantoms. The plastic scintillator material is more water equivalent than polystyrene in terms of its mass collision stopping power and mass scattering power. Measurements were performed for beams of electrons having initial energies of 6 and 18 MeV at depths from 0.2-4.2 cm behind the inhomogeneities. The detector reveals hot and cold spots behind heterogeneities at resolutions equivalent to typical film digitizer spot sizes. Plots of the dose distributions behind air, aluminum, lead, and formulations for cortical and inner bone-equivalent materials are presented. The plastic scintillation detector is suited for measuring the electron dose distribution near an inhomogeneity. 14 refs., 9 figs.

  9. Measurement bias dependence of enhanced bipolar gain degradation at low dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Witczak, S.C.; Lacoe, R.C.; Mayer, D.C. [Aerospace Corp., Los Angeles, CA (United States). Electronics Technology Center; Schrimpf, R.D.; Barnaby, H.J.; Galloway, K.F. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Electrical and Computer Engineering; Pease, R.L. [RLP Research, Inc., Albuquerque, NM (United States); Fleetwood, D.M. [Sandia National Labs., Albuquerque, NM (United States)

    1998-03-01

    Oxide trapped charge, field effects from emitter metallization, and high level injection phenomena moderate enhanced gain degradation of lateral pnp transistors at low dose rates. Hardness assurance tests at elevated irradiation temperatures require larger design margins for low power measurement biases.

  10. A computational study to evaluate indoor gamma dose-rate on the basis of outdoor measurements

    Energy Technology Data Exchange (ETDEWEB)

    Nuccetelli, C.; Menghi, E.; Bochicchio, F. [Istituto Superiore di Sanita, Roma (Italy)

    2006-07-01

    A new method to estimate the indoor gamma dose rate has been developed. This method is based on outdoor gamma dose rate measurements and a computational model that requires the knowledge of some structural and geometrical characteristics of the dwelling. It can be a very useful tool in situations in which it is impossible entering the dwellings to measure the indoor gamma dose rate, such as epidemiological studies and other surveys. To validate the method, estimates and actual indoor measurements have been compared for a sample of dwellings. In a first phase, indoor gamma dose rate estimates were obtained using the detailed dwelling information contained in questionnaire filled-in during the indoor measurements. This first comparison gave excellent results. A more general and less site dependent approach has now been implemented, assuming average values for many indoor parameters instead of using questionnaire data, in order to evaluate the predictive characteristics of this method for a practical use. In this paper, the new procedure is presented and the results obtained till now are summarized. (authors)

  11. Development and Test of a GEM-Based TEPC System for In-Phantom Dose Measurements

    Energy Technology Data Exchange (ETDEWEB)

    C-K Chris Wang

    2007-03-13

    The objectives of this project include: (1) to construct a minature tissue equivalent proportional counter (TEPC) using a gas-electron-multiplier (GEM) foil, and (2) to conduct neutron and gamma-ray dose measurements with the detector embedded in a phantom

  12. Holographic Measurements of Electron-Beam Dose Distributions Around Inhomogeneities in Water

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1976-01-01

    Dose distribution measurements made in a small quartz cell filled with water, and with an Al rod placed in the water are reported. The cell was irradiated vertically from above with monoenergetic 3 MeV electrons from a Van de Graaff accelerator. The holographic interferometric method previously...

  13. Photoneutron leakage from medical accelerators: a comprehensive approach to patient and personnel dose measurement

    Energy Technology Data Exchange (ETDEWEB)

    D' Errico, F.; Curzio, G. [Universita degli Studi di Pisa, Dipartimento di Costruzioni Meccaniche e Nucleari, Pisa (Italy)

    1992-07-01

    Simple and reliable techniques, based on the use of superheated drop neutron detectors (SDD's*), are presented for both medical accelerator personnel exposure monitoring, and the direct measurement of non therapeutic dose equivalent received by patients undergoing high-energy x-ray and electron treatment. (author)

  14. Good agreement between minimal erythema dose test reactions and objective measurements

    DEFF Research Database (Denmark)

    Bodekær, Mette; Philipsen, Peter Alshede; Karlsmark, Tonny

    2013-01-01

    The erythema resulting from the minimal erythema dose (MED) test is subjectively assessed. The evaluator visually grades erythema on an ordinal scale. Both intra- and interobserver variation have been found for this erythema assessment. We wanted to examine if objective measurements could be used...

  15. Characterisation of blue-light stimulated luminescence components in different quartz samples: implications for dose measurement

    Energy Technology Data Exchange (ETDEWEB)

    Jain, M. E-mail: mayank.jain@risoe.dk; Murray, A.S.; Boetter-Jensen, L

    2003-10-01

    Over the last few years, we have become increasingly confident that quartz is a reliable natural dosimeter for sediment dating. Nevertheless, there is only a limited understanding of the behaviour of the different components of optically stimulated luminescence (OSL) from quartz. Recent single-aliquot dose-evaluation protocols seem to be relatively free of complications when applied to quartz dominated by the fast OSL component coming from 325 deg. C TL region, but this may not be true for quartz in which other components are more significant. An adequate understanding of how different OSL components behave during various measurement cycles is critical to ensuring that our dose evaluation protocols are robust and it is also important to our interpretation of the variation of apparent dose with optical stimulation time for identification of partial bleaching. We report here the principal results from measurement of (a) sensitisation, (b) thermal stability, (c) recuperation, and (d) infrared response as a function of stimulation temperature from 3 different samples of sedimentary quartz selected on the basis of relative OSL contribution from different blue light stimulated linearly modulated (LM-OSL) components. We then discuss the implications of these characteristics for dose assessment using the single aliquot regeneration dose protocol.

  16. Online Grid Measurement and ENS Detection for PV Inverter Running on Highly Inductive Grid

    DEFF Research Database (Denmark)

    Timbus, Adrian Vasile; Teodorescu, Remus; Blaabjerg, Frede;

    2004-01-01

    Photovoltaic (PV) and other sources of renewable energy are being used increasingly in grid-connected systems, for which stronger power quality requirements are being issued. Continuous grid monitoring should be considered so as to provide safe connections and disconnections from the grid....... This letter gives an overview of the methods used for online grid measurement with PV inverters. Emphasis is placed on a method based on the injection of a noncharacteristic harmonic in the grid. Since this injection is regarded as a disturbance for the grid, different issues, i.e., the influence on total...

  17. Advanced power cycling test for power module with on-line on-state VCE measurement

    DEFF Research Database (Denmark)

    Choi, Ui-min; Trintis, Ionut; Blaabjerg, Frede

    2015-01-01

    module. The proposed concept can perform various stress conditions which is valid in a real mission profile and it is using a real power converter application with small loss. The concept of the proposed test setup is first presented. Then, the on-line on-state collector-emitter voltage VCE measurement......Recent research has made an effort to improve the reliability of power electronic systems to comply with more stringent constraints on cost, safety, predicted lifetime and availability in many applications. For this, studies about failure mechanisms of power electronic components and lifetime...

  18. Probability effects in anticipation investigated with online behavioural measures (mouse tracking)

    DEFF Research Database (Denmark)

    Bruhn, Pernille; Bærentsen, Klaus B.

    Background: Anticipation of upcoming events is an adaptive mechanism that ensures quick and accurate perception and action. Consequently, lower Reaction Time (RT) and higher accuracy is found in response to events that can be adequately anticipated. However, events in the world happen with varying......-hoc behavioural measures of the anticipatory processes involved. Methods: The present study investigates how knowledge of probability affects real-time anticipatory processes. Behaviour is monitored online by tracking the computer mouse trajectory leading to a required response (mouse-click on Target...

  19. Austrian dose measurements onboard space station MIR and the International Space Station--overview and comparison.

    Science.gov (United States)

    Berger, T; Hajek, M; Summerer, L; Vana, N; Akatov, Y; Shurshakov, V; Arkhangelsky, V

    2004-01-01

    The Atominstitute of the Austrian Universities has conducted various space research missions in the last 12 years in cooperation with the Institute for Biomedical Problems in Moscow. They dealt with the exact determination of the radiation hazards for cosmonauts and the development of precise measurement devices. Special emphasis will be laid on the last experiment on space station MIR the goal of which was the determination of the depth distribution of absorbed dose and dose equivalent in a water filled Phantom. The first results from dose measurements onboard the International Space Station (ISS) will also be discussed. The spherical Phantom with a diameter of 35 cm was developed at the Institute for Biomedical Problems and had 4 channels where dosimeters can be exposed in different depths. The exposure period covered the timeframe from May 1997 to February 1999. Thermoluminescent dosimeters (TLDs) were exposed inside the Phantom, either parallel or perpendicular to the hull of the spacecraft. For the evaluation of the linear energy transfer (LET), the high temperature ratio (HTR) method was applied. Based on this method a mean quality factor and, subsequently, the dose equivalent is calculated according to the Q(LET infinity) relationship proposed in ICRP 26. An increased contribution of neutrons could be detected inside the Phantom. However the total dose equivalent did not increase over the depth of the Phantom. As the first Austrian measurements on the ISS dosimeter packages were exposed for 248 days, starting in February 2001 at six different locations onboard the ISS. The Austrian dosimeter sets for this first exposure on the ISS contained five different kinds of passive thermoluminescent dosimeters. First results showed a position dependent absorbed dose rate at the ISS.

  20. Dose measurements in dental radiology using thermoluminescent dosimetry;Medicoes de dose em radiodiagnostico odontologico utilizando dosimetria termoluminescente

    Energy Technology Data Exchange (ETDEWEB)

    Chiara, Ana Claudia M. de; Costa, Alessandro M. [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras; Pardini, Luiz Carlos [Universidade de Sao Paulo (FORP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Odontologia

    2009-07-01

    The aim of this work was the implementation of a code of practice for dosimetry in dental radiology using the technique of thermoluminescent dosimetry. General principles for the use of thermoluminescent dosimeters were followed. The irradiations were performed using ten X-ray equipment for intra-oral radiography and an X-ray equipment for panoramic radiography. The incident air kerma was evaluated for five different exposure times used in clinical practice for intra-oral radiographs. Using a backscatter factor of 1.2, it was observed that approximately 40% of the entrance skin dose values found for intra-oral radiographs are above the diagnostic reference level recommended in national regulation. Different configurations of voltage and current were used representing the exposure as a child, woman and man for panoramic radiographs. The results obtained for the air kerma area product were respectively 53.3 +- 5.2 mGy.cm{sup 2}, 101.5 +- 9.5 mGy.cm{sup 2} and 116.8 +- 10.4 mGy.cm{sup 2}. The use of thermoluminescent dosimetry requires several procedures before a result is recorded. The use of dosimeters with ionization chambers or semiconductors provides a simple and robust method for routine measurements. However, the use of thermoluminescent dosimetry can be of great value to large-scale surveys to establish diagnostic reference levels. (author)

  1. On-line Measurement of Water-Soluble Ions in Ambient Particles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography (RCFP-IC) was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO42-,NO-3, NO-2, Cl- and F- is below 0.3 μg m-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring.

  2. MO-AB-BRA-03: Calorimetry-Based Absorbed Dose to Water Measurements Using Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Martinez, E; Malin, M; DeWerd, L [University of WI-Madison/ADCL, Madison, WI (United States)

    2015-06-15

    Purpose: Interferometry-based calorimetry is a novel technique to measure radiation-induced temperature changes allowing the measurement of absorbed dose to water (ADW). There are no mechanical components in the field. This technique also has the possibility of obtaining 2D dose distributions. The goal of this investigation is to calorimetrically-measure doses between 2.5 and 5 Gy over a single projection in a photon beam using interferometry and compare the results with doses calculated using the TG-51 linac calibration. Methods: ADW was determined by measuring radiation-induced phase shifts (PSs) of light passing through water irradiated with a 6 MV photon beam. A 9×9×9 cm{sup 3} glass phantom filled with water and placed in an arm of a Michelson interferometer was irradiated with 300, 400, 500 and 600 monitor units. The whole system was thermally insulated to achieve sufficient passive temperature control. The depth of measurement was 4.5 cm with a field size of 7×7 cm{sup 2}. The intensity of the fringe pattern was monitored with a photodiode and used to calculate the time-dependent PS curve. Data was acquired 60 s before and after the irradiation. The radiation-induced PS was calculated by taking the difference in the pre- and post-irradiation drifts extrapolated to the midpoint of the irradiation. Results were compared to computed doses. Results: Average comparison of calculated ADW values with interferometry-measured values showed an agreement to within 9.5%. k=1 uncertainties were 4.3% for calculations and 14.7% for measurements. The dominant source of uncertainty for the measurements was a temperature drift of about 30 µK/s caused by heat conduction from the interferometer’s surroundings. Conclusion: This work presented the first absolute ADW measurements using interferometry in the dose range of linac-based radiotherapy. Future work to improve measurements’ reproducibility includes the implementation of active thermal control techniques.

  3. Measuring on-line compliance in ventilated infants using hot wire anemometry.

    Science.gov (United States)

    Baboolal, R; Kirpalani, H

    1990-10-01

    We investigated the validity of using tidal volume (VT) as measured by the neonatal volume monitor (NVM) to derive respiratory compliance. The NVM is a noninvasive device that measures VT by hot wire anemometry. The quotient of VT and the inflation pressure amplitude from the mechanical ventilator provided a measure of respiratory compliance. This was validated against the single breath occlusion technique in 15 infants (birth weight 0.9 to 4.4 kg). To ensure fully passive expiration, only paralyzed or sedated patients were studied. Only 12 of the 15 infants were analyzed because of limitations in the single breath technique. In three infants the flow-volume curves obtained were alinear, indicating inhomogeneity. In the 12 infants with acceptable single breath data, agreement between the two methods was excellent. Using the expired volume, r2 was .99. We conclude that the NVM can be used to obtain valid estimates of respiratory compliance on-line in intubated infants.

  4. A new method using orthogonal two-frequency grating in online 3D measurement

    Science.gov (United States)

    Peng, Kuang; Cao, Yiping; Wu, Yingchun; Lu, Mingteng

    2016-09-01

    In online 3D measurement, a new method using orthogonal two-frequency grating based on Phase Measuring Profilometry(PMP) is proposed. The modulation of the entire measured object is used to match pixels and this proposed method successfully resolves the contradiction of the demand for different frequency fringes between the extraction of the modulation information and the phase unwrapping. The high-frequency fringe is used to catch the better modulation patterns for pixel matching, and the low-frequency fringe is used to calculate the phase distribution and avoid phase unwrapping error. In addition, to extract the better modulation patterns for pixel matching, the flat filtering window replaces the circular filtering window to avoid the spectrum aliasing phenomenon. The simulations and experiments show its feasibility.

  5. Online devices and measuring systems for the automatic control of newspaper printing

    Science.gov (United States)

    Marszalec, Elzbieta A.; Heikkila, Ismo; Juhola, Helene; Lehtonen, Tapio

    1999-09-01

    The paper reviews the state-of-the-art color measuring systems used for the control of newspaper printing. The printing process requirements are specified and different off-line and on-line color quality control systems, commercially available and under development, are evaluated. Recent market trends in newspaper printing are discussed based on the survey. The study was made on information derived from: conference proceedings (TAGA, IARIGAI, SPIE and IS&T), journals (American Printer, Applied Optics), discussions with experts (GMI, QTI, HONEYWELL, TOBIAS, GretagMacbeth), IFRA Expo'98/Quality Measuring Technologies, commercial brochures, and the Internet. On the background of this review, three different measuring principles, currently, under investigation at VTT Information Technology, are described and their applicability to newspaper printing is evaluated.

  6. SU-F-I-36: In-Utero Dose Measurements Within Postmortem Subjects for Estimating Fetal Doses in Pregnant Patients Examined with Pulmonary Embolism, Trauma, and Appendicitis CT

    Energy Technology Data Exchange (ETDEWEB)

    Lipnharski, I; Quails, N; Carranza, C; Correa, N; Bidari, S; Bickelhaup, M; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: The imaging of pregnant patients is medically necessary in certain clinical situations. The purpose of this work was to directly measure uterine doses in a cadaver scanned with CT protocols commonly performed on pregnant patients in order to estimate fetal dose and assess potential risk. Method: One postmortem subject was scanned on a 320-slice CT scanner with standard pulmonary embolism, trauma, and appendicitis protocols. All protocols were performed with the scan parameters and ranges currently used in clinical practice. Exams were performed both with and without iterative reconstruction to highlight the dose savings potential. Optically stimulated luminescent dosimeters (OSLDs) were inserted into the uterus in order to approximate fetal doses. Results: In the pulmonary embolism CT protocol, the uterus is outside of the primary beam, and the dose to the uterus was under 1 mGy. In the trauma and appendicitis protocols, the uterus is in the primary beam, the fetal dose estimates were 30.5 mGy for the trauma protocol, and 20.6 mGy for the appendicitis protocol. Iterative reconstruction reduced fetal doses by 30%, with uterine doses at 21.3 for the trauma and 14.3 mGy for the appendicitis protocol. Conclusion: Fetal doses were under 1 mGy when exposed to scatter radiation, and under 50 mGy when exposed to primary radiation with the trauma and appendicitis protocols. Consistent with the National Council on Radiation Protection & Measurements (NCRP) and the International Commission on Radiological Protection (ICRP), these doses exhibit a negligible risk to the fetus, with only a small increased risk of cancer. Still, CT scans are not recommended during pregnancy unless the benefits of the exam clearly outweigh the potential risk. Furthermore, when possible, pregnant patients should be examined on CT scanners equipped with iterative reconstruction in order to keep patient doses as low as reasonable achievable.

  7. 3D dose distribution measurements in brachytherapy using radiochromic gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Solc, J., E-mail: jsolc@cmi.c [Czech Metrology Institute-Inspectorate for Ionizing Radiation, Radiova 1, CZ 102 00 Prague 10 (Czech Republic); Sochor, V.; Kacur, M.; Smoldasova, J. [Czech Metrology Institute-Inspectorate for Ionizing Radiation, Radiova 1, CZ 102 00 Prague 10 (Czech Republic)

    2010-07-21

    The paper informs about the joint research project 'Increasing cancer treatment efficacy using 3D brachytherapy' which is a three-year project carried out in cooperation with European national metrology institutes and co-funded by the European Community's Seventh Framework Program for research and technological development. The goal of the project is to improve the measurement and standardization of dose-to-water rate by brachytherapy (BT) sources. The paper gives a summary of the individual parts of the whole project and describes in more detail the task of the Czech Metrology Institute: the determination of spatial distribution of dose-to-water by BT sources using radiochromic gel dosimeters, including a new gel with suppressed diffusion. The response of irradiated gels is evaluated using the optical cone beam computed tomography (CT) technique. The characteristics of the optical CT scanner are discussed with respect to CCD camera performance and light source. The optimized composition of the new gel and its dosimetric properties are highlighted. The results show that the radiochromic gels are convenient for measuring the 3D distribution of dose-to-water and could be an alternative to current methods of dose distribution measurements.

  8. 3D dose distribution measurements in brachytherapy using radiochromic gel dosimeters

    Science.gov (United States)

    Šolc, J.; Sochor, V.; Kačur, M.; Šmoldasová, J.

    2010-07-01

    The paper informs about the joint research project "Increasing cancer treatment efficacy using 3D brachytherapy" which is a three-year project carried out in cooperation with European national metrology institutes and co-funded by the European Community's Seventh Framework Program for research and technological development. The goal of the project is to improve the measurement and standardization of dose-to-water rate by brachytherapy (BT) sources. The paper gives a summary of the individual parts of the whole project and describes in more detail the task of the Czech Metrology Institute: the determination of spatial distribution of dose-to-water by BT sources using radiochromic gel dosimeters, including a new gel with suppressed diffusion. The response of irradiated gels is evaluated using the optical cone beam computed tomography (CT) technique. The characteristics of the optical CT scanner are discussed with respect to CCD camera performance and light source. The optimized composition of the new gel and its dosimetric properties are highlighted. The results show that the radiochromic gels are convenient for measuring the 3D distribution of dose-to-water and could be an alternative to current methods of dose distribution measurements.

  9. Generation and dose distribution measurement of flash x-ray in KALI-5000 system

    Science.gov (United States)

    Menon, Rakhee; Roy, Amitava; Mitra, S.; Sharma, A.; Mondal, J.; Mittal, K. C.; Nagesh, K. V.; Chakravarthy, D. P.

    2008-10-01

    Flash x-ray generation studies have been carried out in KALI-5000 Pulse power system. The intense relativistic electron beam has been bombarded on a tantalum target at anode to produce flash x-ray via bremsstrahlung conversion. The typical electron beam parameter was 360 kV, 18 kA, and 100 ns, with a few hundreds of A/cm2 current density. The x-ray dose has been measured with calcium sulfate:dysposium (CaSO4:Dy) thermoluminescent dosimeter and the axial dose distribution has been characterized. It has been observed that the on axis dose falls of with distance ˜1/xn, where n varies from 1.8 to 1.85. A maximum on axis dose of 46 mrad has been measured at 1 m distance from the source. A plastic scintillator with optical fiber coupled to a photomultiplier tube has been developed to measure the x-ray pulse width. The typical x-ray pulse width varied from 50 to 80 ns.

  10. Benchmark measurements and simulations of dose perturbations due to metallic spheres in proton beams

    Science.gov (United States)

    Newhauser, Wayne D.; Rechner, Laura; Mirkovic, Dragan; Yepes, Pablo; Koch, Nicholas C.; Titt, Uwe; Fontenot, Jonas D.; Zhang, Rui

    2014-01-01

    Monte Carlo simulations are increasingly used for dose calculations in proton therapy due to its inherent accuracy. However, dosimetric deviations have been found using Monte Carlo code when high density materials are present in the proton beam line. The purpose of this work was to quantify the magnitude of dose perturbation caused by metal objects. We did this by comparing measurements and Monte Carlo predictions of dose perturbations caused by the presence of small metal spheres in several clinical proton therapy beams as functions of proton beam range, spread-out Bragg peak width and drift space. Monte Carlo codes MCNPX, GEANT4 and Fast Dose Calculator (FDC) were used. Generally good agreement was found between measurements and Monte Carlo predictions, with the average difference within 5% and maximum difference within 17%. The modification of multiple Coulomb scattering model in MCNPX code yielded improvement in accuracy and provided the best overall agreement with measurements. Our results confirmed that Monte Carlo codes are well suited for predicting multiple Coulomb scattering in proton therapy beams when short drift spaces are involved. PMID:25147474

  11. On-line measurements of particle-bound reactive oxygen species (ROS) in Beijing wintertime air

    Science.gov (United States)

    Steimer, Sarah; Wragg, Francis; Kalberer, Markus

    2017-04-01

    Reactive oxygen species (ROS), present in particles or generated by particle components upon deposition of particles in the human lung, are widely thought to be one of the main contributors to particle-related toxicity. However, there is so far only relatively little data available on their concentrations in ambient air, which makes it difficult to gauge their impact on air quality. Recent studies have shown that a large fraction of particle-bound ROS in secondary organic aerosol is relatively short-lived, with lifetimes of several minutes. Traditional off-line sampling with high-volume samplers is therefore likely to severely underestimate ROS concentrations, showing the need for using on-line instrumentation. We have recently developed a compact on-line instrument for the measurement of particle-bound ROS (OPROSI). To measure ROS concentrations, particles are continuously extracted and the extract is reacted with 2'7'-dichlorofluorescein (DCFH) in presence of horseradish peroxidase (HRP). This leads to formation of a fluorescent dye, which is detected spectroscopically. The instrument allows for up to 16 h of continuous measurement with a time resolution of ≤12 min and a limit of detection of 3.85 nmol [H2O2] equivalent per m3 air. For this study, we have used the OPROSI to continuously measure the concentration of particle-bound ROS in Beijing wintertime air during the first half of the Air Pollution and Human Health in a Developing Megacity (APHH-Beijing) campaign in November and December 2016. Measured ROS data are compared with other air pollution parameters such as total particulate mass, ozone and NOx as well as with meteorological measurements such as temperature and humidity.

  12. Application of TL dosemeters for dose distribution measurements at high temperatures in nuclear reactors.

    Science.gov (United States)

    Osvay, M; Deme, S

    2006-01-01

    Al2O3:Mg,Y ceramic thermoluminescence dosemeters were developed at the Institute of Isotopes for high dose applications at room temperatures. The glow curve of Al2O3:Mg,Y exhibits two peaks--one at 250 degrees C (I) and another peak at approximately 400 degrees C (II). In order to extend the application of these dosemeters to high temperatures, the effect of irradiation temperature was investigated using temperature controlled heating system during high dose irradiation at various temperatures (20-100 degrees C). The new calibration and measuring method has been successfully applied for dose mapping within the hermetic zone of the Paks Nuclear Power Plant even at high temperature parts of blocks.

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

    Science.gov (United States)

    Akatov YuA; Arkhangelsky, V V; Kovalev, E E; Spurny, F; Votochkova, I

    1989-01-01

    In this paper we present absorbed dose measurements with glass thermoluminescent detectors on external surface of satellites of Kosmos-serie flying in 1983-87. Experiments were performed with thermoluminescent aluminophosphate glasses of thicknesses 0.1, 0.3, 0.4, 0.5, and 1 mm. They were exposed in sets of total thickness between 5 and 20 mm, which were protected against sunlight with thin aluminized foils. In all missions, extremely high absorbed dose values were observed in the first layers of detectors, up to the thickness of 0.2 to 0.5 gcm-2. These experimental results confirm that, during flights at 250 to 400 km, doses on the surface of the satellites are very high, due to the low energy component of the proton and electron radiation.

  14. A comparison of measured and calculated organ doses from CT examinations

    Energy Technology Data Exchange (ETDEWEB)

    Calzado, A.; Ruiz Sanz, S.; Melchor, M.; Vano, E. [Universidad Complutense, Madrid (Spain). Facultad de Medicina

    1995-12-31

    Organ doses from a set of frequent CT examinations have been estimated from measurements in a physical anthropomorphic phantom (Remab system) by using thermoluminescence dosemeters. For the same examination techniques, organ dose coefficients (taken from the literature) obtained by Monte Carlo techniques and using mathematical phantoms. The results arrived at by the two methods are compared, trying to explain the most significant differences and their influence on the estimated values of effective dose. The experimental and calculated outcomes from such simulations are also compared to the mean dosimetric results on patients from a 1991 regional survey of CT practice in the area of Madrid. Some comments about the complementary use of information coming from both methods are made. (Author).

  15. Measurements of Dose Distribution outside the Treatment Area in case of Radiotherapy Treatment using Polystyrene Phantom

    CERN Document Server

    Ahmed, Md Farid; Ahmed, G U; Miah, F K

    2012-01-01

    Dose distribution (depthwise and laterally) to organs outside the radiotherapy treatment field can be significant and therefore is of clinical interest from the radiation protection point of view. In the present work, measurements were performed in a locally fabricated polystyrene phantom using TLD chips (LiF-100) for different teletherapy units (Cobalt-60 gamma ray, 120 kVp X-ray and 250 kVp X-ray) to estimate the dose distribution at distances up to 40 cm from the field edge along the central axes of the field size. Finally, the dose distribution for Cobalt-60 beam energy is parameterized as a function of depth, distance from field edge, and field size and shape.

  16. Assessment of target volume doses in radiotherapy based on the standard and measured calibration curves

    Directory of Open Access Journals (Sweden)

    Gholamreza Fallah Mohammadi

    2015-01-01

    Full Text Available Context: In radiation treatments, estimation of the dose distribution in the target volume is one of the main components of the treatment planning procedure. To estimate the dose distribution, the information of electron densities is necessary. The standard curves determined by computed tomography (CT scanner that may be different from that of other oncology centers. In this study, the changes of dose calculation due to the different calibration curves (HU-ρel were investigated. Materials and Methods: Dose values were calculated based on the standard calibration curve that was predefined for the treatment planning system (TPS. The calibration curve was also extracted from the CT images of the phantom, and dose values were calculated based on this curve. The percentage errors of the calculated values were determined. Statistical Analysis Used: The statistical analyses of the mean differences were performed using the Wilcoxon rank-sum test for both of the calibration curves. Results and Discussion: The results show no significant difference for both of the measured and standard calibration curves (HU-ρel in 6, 15, and 18 MeV energies. In Wilcoxon ranked sum nonparametric test for independent samples with P < 0.05, the equality of monitor units for both of the curves to transfer 200 cGy doses to reference points was resulted. The percentage errors of the calculated values were lower than 2% and 1.5% in 6 and 15 MeV, respectively. Conclusion: From the results, it could be concluded that the standard calibration curve could be used in TPS dose calculation accurately.

  17. Factors affecting quality for beta dose rate measurements using ISO 6980 series I reference sources

    Energy Technology Data Exchange (ETDEWEB)

    Burns, R.E. Jr.; O`Brien, J.M. Jr. [Atlan-Tech, Rosewll, GA (United States)

    1993-12-31

    Atlan-Tech, Inc. has performed several calibrations of ISO 6980 Series 1 reference beta sources over the past two to three years. There were many problems encountered in attempting to compare the results of these calibrations with those from other laboratories, indicating the need for more standardization in the methodology employed for the measurement of the absorbed dose rate from ISO 6980 Series 1 reference beta sources. This document describes some of the problems encountered in attempting to intercompare results of beta dose-rate measurements. It proposes some solutions in an attempt to open a dialogue among facilities using reference beta standards for the purpose of promoting better measurement quality assurance through data intercomparison.

  18. Electron paramagnetic resonance measurements of absorbed dose in teeth from citizens of Ozyorsk

    Energy Technology Data Exchange (ETDEWEB)

    Wieser, A.; Semiochkina, N. [Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Institute of Radiation Protection, Neuherberg (Germany); Vasilenko, E.; Aladova, E.; Smetanin, M. [Southern Urals Biophysics Institute, Ozyorsk (Russian Federation); Fattibene, P. [Istituto Superiore di Sanita, Rome (Italy)

    2014-05-15

    In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960. (orig.)

  19. Electrical test methods for on-line fuel cell ohmic resistance measurement

    Science.gov (United States)

    Cooper, K. R.; Smith, M.

    The principles and trade-offs of four electrical test methods suitable for on-line measurement of the ohmic resistance (R Ω) of fuel cells is presented: current interrupt, AC resistance, high frequency resistance (HFR), and electrochemical impedance spectroscopy (EIS). The internal resistance of a proton exchange membrane (PEM) fuel cell determined with the current interrupt, HFR and EIS techniques is compared. The influence of the AC amplitude and frequency of the HFR measurement on the observed ohmic resistance is examined, as is the ohmic resistance extracted from the EIS data by modeling the spectra with a transmission line model for porous electrodes. The ohmic resistance of a H 2/O 2 PEM fuel cell determined via the three methods was within 10-30% of each other. The current interrupt technique consistently produced measured cell resistances that exceeded those of the other two techniques. For the HFR technique, the frequency at which the measurement was conducted influenced the measured resistance (i.e., higher frequency providing smaller R Ω), whereas the AC amplitude did not effect the observed value. The difference in measured ohmic resistance between these techniques exceeds that reasonably accounted for by measurement error. The source of the discrepancy between current interrupt and impedance-based methods is attributed to the difference in the response of a non-uniformly polarized electrode, such as a porous electrode with non-negligible ohmic resistance, to a large perturbation (current interrupt event) as compared to a small perturbation (impedance measurement).

  20. Measurement of in-phantom neutron flux and gamma dose in Tehran research reactor boron neutron capture therapy beam line

    OpenAIRE

    Elham Bavarnegin; Alireza Sadremomtaz; Hossein Khalafi; Yaser Kasesaz

    2016-01-01

    Aim: Determination of in-phantom quality factors of Tehran research reactor (TRR) boron neutron capture therapy (BNCT) beam. Materials and Methods: The doses from thermal neutron reactions with 14N and 10B are calculated by kinetic energy released per unit mass approach, after measuring thermal neutron flux using neutron activation technique. Gamma dose is measured using TLD-700 dosimeter. Results: Different dose components have been measured in a head phantom which has been designed an...

  1. Metrological traceability in education: A practical online system for measuring and managing middle school mathematics instruction

    Science.gov (United States)

    Torres Irribarra, D.; Freund, R.; Fisher, W.; Wilson, M.

    2015-02-01

    Computer-based, online assessments modelled, designed, and evaluated for adaptively administered invariant measurement are uniquely suited to defining and maintaining traceability to standardized units in education. An assessment of this kind is embedded in the Assessing Data Modeling and Statistical Reasoning (ADM) middle school mathematics curriculum. Diagnostic information about middle school students' learning of statistics and modeling is provided via computer-based formative assessments for seven constructs that comprise a learning progression for statistics and modeling from late elementary through the middle school grades. The seven constructs are: Data Display, Meta-Representational Competence, Conceptions of Statistics, Chance, Modeling Variability, Theory of Measurement, and Informal Inference. The end product is a web-delivered system built with Ruby on Rails for use by curriculum development teams working with classroom teachers in designing, developing, and delivering formative assessments. The online accessible system allows teachers to accurately diagnose students' unique comprehension and learning needs in a common language of real-time assessment, logging, analysis, feedback, and reporting.

  2. Assessing segmentation processes by click detection: online measure of statistical learning, or simple interference?

    Science.gov (United States)

    Franco, Ana; Gaillard, Vinciane; Cleeremans, Axel; Destrebecqz, Arnaud

    2015-12-01

    Statistical learning can be used to extract the words from continuous speech. Gómez, Bion, and Mehler (Language and Cognitive Processes, 26, 212-223, 2011) proposed an online measure of statistical learning: They superimposed auditory clicks on a continuous artificial speech stream made up of a random succession of trisyllabic nonwords. Participants were instructed to detect these clicks, which could be located either within or between words. The results showed that, over the length of exposure, reaction times (RTs) increased more for within-word than for between-word clicks. This result has been accounted for by means of statistical learning of the between-word boundaries. However, even though statistical learning occurs without an intention to learn, it nevertheless requires attentional resources. Therefore, this process could be affected by a concurrent task such as click detection. In the present study, we evaluated the extent to which the click detection task indeed reflects successful statistical learning. Our results suggest that the emergence of RT differences between within- and between-word click detection is neither systematic nor related to the successful segmentation of the artificial language. Therefore, instead of being an online measure of learning, the click detection task seems to interfere with the extraction of statistical regularities.

  3. Introducing process analytical technology (PAT) in filamentous cultivation process development: comparison of advanced online sensors for biomass measurement

    DEFF Research Database (Denmark)

    Rønnest, Nanna Petersen; Stocks, Stuart M.; Eliasson Lantz, Anna

    2011-01-01

    The recent process analytical technology (PAT) initiative has put an increased focus on online sensors to generate process-relevant information in real time. Specifically for fermentation, however, introduction of online sensors is often far from straightforward, and online measurement of biomass...... is one of the best examples. The purpose of this study was therefore to compare the performance of various online biomass sensors, and secondly to demonstrate their use in early development of a filamentous cultivation process. Eight Streptomyces coelicolor fed-batch cultivations were run as part...... of process development in which the pH, the feeding strategy, and the medium composition were varied. The cultivations were monitored in situ using multi-wavelength fluorescence (MWF) spectroscopy, scanning dielectric (DE) spectroscopy, and turbidity measurements. In addition, we logged all of the classical...

  4. Business in the Hands of Consumers: A Scale for Measuring Online Resale Motivations

    Directory of Open Access Journals (Sweden)

    Myriam ERTZ

    2016-12-01

    Full Text Available The web channel is increasingly a central aspect of the second-hand economy and, as such, favours also more sustainable post-consumption processes. This is why the field of online reselling appears increasingly important. Besides, the ever broadening scope of online reselling is key to the success of new online intermediaries that position themselves in the broader movement of collaborative consumption. While, consumers’ attachment for secondhand exchanges is not new, they have largely embraced its online declination. In response to these evolutions in the online retail environment, traditional retail companies have therefore started to create online consumer marketplaces in which consumers exchange goods by themselves. In order to best adapt such online marketplaces to consumers, it is therefore critically important to gain a better understanding of the driving forces behind online reselling. At present, knowledge about what motivates consumers to resell products online is limited. This article outlines the development and validation process of an online resale motivation (ORM scale via three studies involving 1,119 respondents. Study 1 presents the ORM scale development process and resulting multi-dimensional construct, including protester, economic, generative, recreational, practical and social facets. Study 2 replicates the scale and investigates its predictive capabilities. More specifically, the ORM scale predicts successfully online resale frequency. Consumers who are more highly motivated to resell online, will indeed resell more often online. Study 3 examines the mediating role of ORM on the relationship between planned resale intentions (PRI and online resale behaviour. The fact that consumers plan to resell a product prior to its purchase, will not directly lead them to increase the frequency at which they resell online. Rather, it is because they perceive positive economic, practical and recreational outcomes associated with

  5. Linear and volume measurements of pulmonary nodules at different CT dose levels. Interscan and interscan analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hein, P.A.; Romano, V.C.; Rogalla, P.; Klessen, C.; Lembcke, A.; Bauknecht, H.C. [Charite-Universitaetsmedizin Berlin (Germany). Inst. fuer Radiologie; Dicken, V.; Bornemann, L. [MeVis Research, Bremen (Germany)

    2009-01-15

    Purpose: To compare the interobserver variability of the unidimensional diameter and volume measurements of pulmonary nodules in an intrascan and interscan analysis using semi-automated segmentation software on ultra-low-dose computed tomography (ULD-CT) and standard dose CT (SD-CT) data. Materials and Methods: In 33 patients with pulmonary nodules, two chest multi-slice CT (MSCT) datasets (1 mm slice thickness; 20 % reconstruction overlap) had been consecutively acquired with an ultra-low dose (120 kV, 5 mAs) and standard dose technique (120 kV, 75 mAs). MSCT data was retrospectively analyzed using the segmentation software OncoTREAT (MeVis, Bremen, Germany, version 1.3). The volume of 229 solid pulmonary nodules included in the analysis as well as the largest diameter according to RECIST (Response Evaluation Criteria for Solid Tumors) were measured by two radiologists. Interobserver variability was calculated and SD-CT and ULD-CT data compared in an intrascan and interscan analysis. Results: The median nodule diameter (n = 229 nodules) was registered with 8.2 mm (range: 2.8 to 43.6 mm, mean: 10.8 mm). The nodule volume ranged between 0.01 and 49.1 ml (median 0.1 ml, mean 1.5 ml). With respect to interobserver variability, the intrascan analysis did not reveal statistically significant differences (p > 0.05) between ULD-CT and SD-CT with broader limits of agreement for relative differences of RECIST measurements (-31.0 % + 27.0 % mean -2.0 % for SD-CT; -27.0 % + 38.6 %, mean 5.8 % for ULD-CT) than for volume measurements (-9.4 %, 8.0 %, mean 0.7 % for SD-CT; -13 %, 13 %, mean 0.0 % for ULD-CT). The interscan analysis showed broadened 95 % confidence intervals for volume measurements (-26.5 % 29.1 % mean 1.3 %, and -25.2 %, 29.6 %, mean 2.2 %) but yielded comparable limits of agreement for RECIST measurements. Conclusion: The variability of nodule volumetry assessed by semi-automated segmentation software as well as nodule size determination by RECIST appears to be

  6. SU-E-T-616: Plan Quality Assessment of Both Treatment Planning System Dose and Measurement-Based 3D Reconstructed Dose in the Patient

    Energy Technology Data Exchange (ETDEWEB)

    Olch, A [University of Southern California, Los Angeles, CA (United States)

    2015-06-15

    Purpose: Systematic radiotherapy plan quality assessment promotes quality improvement. Software tools can perform this analysis by applying site-specific structure dose metrics. The next step is to similarly evaluate the quality of the dose delivery. This study defines metrics for acceptable doses to targets and normal organs for a particular treatment site and scores each plan accordingly. The input can be the TPS or the measurement-based 3D patient dose. From this analysis, one can determine whether the delivered dose distribution to the patient receives a score which is comparable to the TPS plan score, otherwise replanning may be indicated. Methods: Eleven neuroblastoma patient plans were exported from Eclipse to the Quality Reports program. A scoring algorithm defined a score for each normal and target structure based on dose-volume parameters. Each plan was scored by this algorithm and the percentage of total possible points was obtained. Each plan also underwent IMRT QA measurements with a Mapcheck2 or ArcCheck. These measurements were input into the 3DVH program to compute the patient 3D dose distribution which was analyzed using the same scoring algorithm as the TPS plan. Results: The mean quality score for the TPS plans was 75.37% (std dev=14.15%) compared to 71.95% (std dev=13.45%) for the 3DVH dose distribution. For 3/11 plans, the 3DVH-based quality score was higher than the TPS score, by between 0.5 to 8.4 percentage points. Eight/11 plans scores decreased based on IMRT QA measurements by 1.2 to 18.6 points. Conclusion: Software was used to determine the degree to which the plan quality score differed between the TPS and measurement-based dose. Although the delivery score was generally in good agreement with the planned dose score, there were some that improved while there was one plan whose delivered dose quality was significantly less than planned. This methodology helps evaluate both planned and delivered dose quality. Sun Nuclear Corporation has

  7. Natural Radioactivity Measurements and Radiation Dose Estimation in Some Sedimentary Rock Samples in Turkey

    Directory of Open Access Journals (Sweden)

    I. Akkurt

    2014-01-01

    Full Text Available The natural radioactivity existed since creation of the universe due to the long life time of some radionuclides. This natural radioactivity is caused by γ-radiation originating from the uranium and thorium series and 40K. In this study, the gamma radiation has been measured to determine natural radioactivity of 238U, 232Th, and 40K in collected sedimentary rock samples in different places of Turkey. The measurements have been performed using γ-ray spectrometer containing NaI(Tl detector and multichannel analyser (MCA. Absorbed dose rate (D, annual effective dose (AED, radium equivalent activities (Raeq, external hazard index (Hex, and internal hazard index (Hin associated with the natural radionuclide were calculated to assess the radiation hazard of the natural radioactivity in the sedimentary rock samples. The average values of absorbed dose rate in air (D, annual effective dose (AED, radium equivalent activity (Raeq, external hazard index (Hex, and internal hazard index (Hin were calculated and these were 45.425 nGy/h, 0.056 mSv/y, 99.014 Bq/kg, 0.267, and 0.361, respectively.

  8. Measurements of X-ray doses and spectra produced by picosecond laser-irradiated solid targets.

    Science.gov (United States)

    Yang, Bo; Qiu, Rui; Yu, Minghai; Jiao, Jinlong; Lu, Wei; Yan, Yonghong; Zhang, Bo; Zhang, Zhimeng; Zhou, Weimin; Li, Junli; Zhang, Hui

    2017-02-09

    Experiments have shown that high-intensity laser interaction with a solid target can generate significant X-ray doses. This study was conducted to determine the X-ray doses and spectra produced for picosecond laser-irradiated solid targets. The photon doses and X-ray spectra in the laser forward and side directions were measured using an XG III ps 300 TW laser system. For laser intensities of 7×10(18)-4×10(19)W/cm(2), the maximum photon dose was 16.8 mSv at 50cm with a laser energy of ~153J on a 1-mm Ta target. The photon dose in the forward direction increased more significantly with increasing laser intensity than that in the side direction. For photon energies >300keV, the X-ray spectrum can be fit with an effective temperature distribution of the exponential form, dN/dE = k× exp(-E/Tx). The X-ray temperature Tx increased with the laser intensity in the forward direction with values of 0.46-0.75MeV. Tx was less strongly correlated with the laser intensity in the side direction with values of 0.29-0.32MeV. The escaping electron spectrum was also measured. The measured electron temperature was correlated with the electron temperature predicted by the ponderomotive law. The observations in this experiment were also investigated numerically. A good agreement was observed between the experimental and simulation results.

  9. Evaluation of NO+ reagent ion chemistry for online measurements of atmospheric volatile organic compounds

    Science.gov (United States)

    Koss, Abigail R.; Warneke, Carsten; Yuan, Bin; Coggon, Matthew M.; Veres, Patrick R.; de Gouw, Joost A.

    2016-07-01

    NO+ chemical ionization mass spectrometry (NO+ CIMS) can achieve fast (1 Hz and faster) online measurement of trace atmospheric volatile organic compounds (VOCs) that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument). Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC) interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1) NO+ is useful for isomerically resolved measurements of carbonyl species; (2) NO+ can achieve sensitive detection of small (C4-C8) branched alkanes but is not unambiguous for most; and (3) compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12-C15) n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.

  10. Online Advertising

    OpenAIRE

    Goldfarb, Avi; Tucker, Catherine Elizabeth

    2011-01-01

    This chapter explores what makes online advertising different from traditional advertising channels. We argue that online advertising differs from traditional advertising channels in two important ways: measurability and targetability. Measurability is higher because the digital nature of online advertising means that responses to ads can be tracked relatively easily. Targetability is higher because data can be automatically tracked at an individual level, and it is relatively easy to show di...

  11. Comparison of measured and estimated maximum skin doses during CT fluoroscopy lung biopsies

    Energy Technology Data Exchange (ETDEWEB)

    Zanca, F., E-mail: Federica.Zanca@med.kuleuven.be [Department of Radiology, Leuven University Center of Medical Physics in Radiology, UZ Leuven, Herestraat 49, 3000 Leuven, Belgium and Imaging and Pathology Department, UZ Leuven, Herestraat 49, Box 7003 3000 Leuven (Belgium); Jacobs, A. [Department of Radiology, Leuven University Center of Medical Physics in Radiology, UZ Leuven, Herestraat 49, 3000 Leuven (Belgium); Crijns, W. [Department of Radiotherapy, UZ Leuven, Herestraat 49, 3000 Leuven (Belgium); De Wever, W. [Imaging and Pathology Department, UZ Leuven, Herestraat 49, Box 7003 3000 Leuven, Belgium and Department of Radiology, UZ Leuven, Herestraat 49, 3000 Leuven (Belgium)

    2014-07-15

    Purpose: To measure patient-specific maximum skin dose (MSD) associated with CT fluoroscopy (CTF) lung biopsies and to compare measured MSD with the MSD estimated from phantom measurements, as well as with the CTDIvol of patient examinations. Methods: Data from 50 patients with lung lesions who underwent a CT fluoroscopy-guided biopsy were collected. The CT protocol consisted of a low-kilovoltage (80 kV) protocol used in combination with an algorithm for dose reduction to the radiology staff during the interventional procedure, HandCare (HC). MSD was assessed during each intervention using EBT2 gafchromic films positioned on patient skin. Lesion size, position, total fluoroscopy time, and patient-effective diameter were registered for each patient. Dose rates were also estimated at the surface of a normal-size anthropomorphic thorax phantom using a 10 cm pencil ionization chamber placed at every 30°, for a full rotation, with and without HC. Measured MSD was compared with MSD values estimated from the phantom measurements and with the cumulative CTDIvol of the procedure. Results: The median measured MSD was 141 mGy (range 38–410 mGy) while the median cumulative CTDIvol was 72 mGy (range 24–262 mGy). The ratio between the MSD estimated from phantom measurements and the measured MSD was 0.87 (range 0.12–4.1) on average. In 72% of cases the estimated MSD underestimated the measured MSD, while in 28% of the cases it overestimated it. The same trend was observed for the ratio of cumulative CTDIvol and measured MSD. No trend was observed as a function of patient size. Conclusions: On average, estimated MSD from dose rate measurements on phantom as well as from CTDIvol of patient examinations underestimates the measured value of MSD. This can be attributed to deviations of the patient's body habitus from the standard phantom size and to patient positioning in the gantry during the procedure.

  12. A Benefit Measurement Framework for an Online Contract Change Management System

    Institute of Scientific and Technical Information of China (English)

    Ming Sun; Tejas Oza

    2008-01-01

    The contract change management (CCM) system is an online collaboration tool, which supports the contract change management process of new engineering contract (NEC) contract. It is currently used in practice on a wide range of civil, power, and building projects in the UK. The aim of this study is first to iden-tify the tangible and intangible benefits of the system through a user survey; then to develop a framework to measure these benefits. A questionnaire survey is conducted, which reveals that CCM can help project teams improve process effectiveness, reduce risk of process failures, and increase the compliance with NEC requirements. Subsequently, a spreadsheet tool is developed to allow CCM users to calculate the tan-gible cost savings as a result of using the system. For intangible benefits, a change management maturity model (CM3) is developed, which provides a measurement framework for assessing the improvement of a project team's capability in dealing with contract changes.

  13. Solving of some Problems with On-Line Mode Measurement of Partial Discharges

    Directory of Open Access Journals (Sweden)

    Karel Zalis

    2004-01-01

    Full Text Available This paper deals with the problems discussing the transition from off-line diagnostic methods to on-line ones. Based on the experience with commercial partial discharge measuring equipment a new digital system for the evaluation of partial discharge measurement including software and hardware facilities has been developed at the Czech Technical University in Prague. Two expert systems work in this complex evaluating system: a rule-based expert system performing an amplitude analysis of partial discharge impulses for determining the damage of the insulation system, and a neural network which is used for a phase analysis of partial discharge impulses to determine the kind of partial discharge activity. Problem of the elimination of disturbances is also discussed.

  14. Comparison of measured and Monte Carlo calculated dose distributions in inhomogeneous phantoms in clinical electron beams

    Science.gov (United States)

    Doucet, R.; Olivares, M.; DeBlois, F.; Podgorsak, E. B.; Kawrakow, I.; Seuntjens, J.

    2003-08-01

    Calculations of dose distributions in heterogeneous phantoms in clinical electron beams, carried out using the fast voxel Monte Carlo (MC) system XVMC and the conventional MC code EGSnrc, were compared with measurements. Irradiations were performed using the 9 MeV and 15 MeV beams from a Varian Clinac-18 accelerator with a 10 × 10 cm2 applicator and an SSD of 100 cm. Depth doses were measured with thermoluminescent dosimetry techniques (TLD 700) in phantoms consisting of slabs of Solid WaterTM (SW) and bone and slabs of SW and lung tissue-equivalent materials. Lateral profiles in water were measured using an electron diode at different depths behind one and two immersed aluminium rods. The accelerator was modelled using the EGS4/BEAM system and optimized phase-space files were used as input to the EGSnrc and the XVMC calculations. Also, for the XVMC, an experiment-based beam model was used. All measurements were corrected by the EGSnrc-calculated stopping power ratios. Overall, there is excellent agreement between the corrected experimental and the two MC dose distributions. Small remaining discrepancies may be due to the non-equivalence between physical and simulated tissue-equivalent materials and to detector fluence perturbation effect correction factors that were calculated for the 9 MeV beam at selected depths in the heterogeneous phantoms.

  15. Comparison of measured and Monte Carlo calculated dose distributions in inhomogeneous phantoms in clinical electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Doucet, R [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); Olivares, M [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); DeBlois, F [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); Podgorsak, E B [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada); Kawrakow, I [National Research Council Canada, Ionizing Radiation Standards Group, Ottawa K1A 0R6, Canada (Canada); Seuntjens, J [Medical Physics Unit, McGill University, Montreal General Hospital, 1650 Ave Cedar, Montreal H3G 1A4 (Canada)

    2003-08-07

    Calculations of dose distributions in heterogeneous phantoms in clinical electron beams, carried out using the fast voxel Monte Carlo (MC) system XVMC and the conventional MC code EGSnrc, were compared with measurements. Irradiations were performed using the 9 MeV and 15 MeV beams from a Varian Clinac-18 accelerator with a 10 x 10 cm{sup 2} applicator and an SSD of 100 cm. Depth doses were measured with thermoluminescent dosimetry techniques (TLD 700) in phantoms consisting of slabs of Solid Water{sup TM} (SW) and bone and slabs of SW and lung tissue-equivalent materials. Lateral profiles in water were measured using an electron diode at different depths behind one and two immersed aluminium rods. The accelerator was modelled using the EGS4/BEAM system and optimized phase-space files were used as input to the EGSnrc and the XVMC calculations. Also, for the XVMC, an experiment-based beam model was used. All measurements were corrected by the EGSnrc-calculated stopping power ratios. Overall, there is excellent agreement between the corrected experimental and the two MC dose distributions. Small remaining discrepancies may be due to the non-equivalence between physical and simulated tissue-equivalent materials and to detector fluence perturbation effect correction factors that were calculated for the 9 MeV beam at selected depths in the heterogeneous phantoms.

  16. Feasibility study of a simple approximation algorithm for in-vivo dose reconstruction by using the transit dose measured using an EPID

    Science.gov (United States)

    Hwang, Ui-Jung; Song, Mi Hee; Baek, Tae Seong; Chung, Eun Ji; Yoon, Myonggeun

    2015-02-01

    The purpose of this study is to verify the accuracy of the dose delivered to the patient during intensity-modulated radiation therapy (IMRT) by using in-vivo dosimetry and to avoid accidental exposure to healthy tissues and organs close to tumors. The in-vivo dose was reconstructed by back projection of the transit dose with a simple approximation that considered only the percent depth dose and inverse square law. While the average gamma index for comparisons of dose distributions between the calculated dose map and the film measurement was less than the one for 96.3% of all pixels with the homogeneous phantom, the passing rate was reduced to 92.8% with the inhomogeneous phantom, suggesting that the reduction was apparently due to the inaccuracy of the reconstruction algorithm for inhomogeneity. The proposed method of calculating the dose inside a phantom was of comparable or better accuracy than the treatment planning system, suggesting that it can be used to verify the accuracy of the dose delivered to the patient during treatment.

  17. RADIATION DOSE MEASUREMENTS FOR HIGH-INTENSITY LASER INTERACTIONS WITH SOLID TARGETS AT SLAC.

    Science.gov (United States)

    Liang, T; Bauer, J; Cimeno, M; Ferrari, A; Galtier, E; Granados, E; Lee, H J; Liu, J; Nagler, B; Prinz, A; Rokni, S; Tran, H; Woods, M

    2016-12-01

    A systematic study of photon and neutron radiation doses generated in high-intensity laser-solid interactions is underway at SLAC National Accelerator Laboratory. These laser-solid experiments are being performed using a 25 TW (up to 1 J in 40 fs) femtosecond pulsed Ti:sapphire laser at the Linac Coherent Light Source's (LCLS) Matter in Extreme Conditions (MEC) facility. Radiation measurements were performed with passive and active detectors deployed at various locations inside and outside the target chamber. Results from radiation dose measurements for laser-solid experiments at SLAC MEC in 2014 with peak intensity between 10(18) and 7.1 × 10(19) W cm(-2) are presented.

  18. Gamma spectrum, count rate, and dose rate measurements of the Columbia riverbank from Vernita to Sacajawea

    Energy Technology Data Exchange (ETDEWEB)

    Grande, L.A.

    1966-01-31

    The purpose of this study was to evaluate radiological conditions that exist on the riverbank of the Columbia River. Included was a comparative study of the suitability of three instruments to measure the dose rates. These instruments were a NaI (T1) scintillation counter normally used for aerial monitoring, a bioplastic scintillation counter normally used as a road monitor, and a portable 40 liter ionization chamber normally used to measure very low gamma dose rates. The selection of representative sites for the comparative study was based on an initial GM survey of the general areas in question. Seven sites were studied--from Vernita Ferry Landing above the Hanford project to Sacajawea Park below Pasco.

  19. Radiation Dose Measurement for High-Intensity Laser Interactions with Solid Targets at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Taiee [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-09-25

    A systematic study of photon and neutron radiation doses generated in high-intensity laser-solid interactions is underway at SLAC National Accelerator Laboratory. We found that these laser-solid experiments are being performed using a 25 TW (up to 1 J in 40 fs) femtosecond pulsed Ti:sapphire laser at the Linac Coherent Light Source’s (LCLS) Matter in Extreme Conditions (MEC) facility. Additionally, radiation measurements were performed with passive and active detectors deployed at various locations inside and outside the target chamber. Results from radiation dose measurements for laser-solid experiments at SLAC MEC in 2014 with peak intensity between 1018 to 7.1x1019 W/cm2 are presented.

  20. A Low LET Radiation Spectrometer for Measuring Particle Doses in Space and Aircraft

    Science.gov (United States)

    Stassinopoulos, E. G.; Stauffer, C. A.; Brucker, G. J.; Dachev, T. P.; Day, John H. (Technical Monitor)

    2002-01-01

    This paper presents experimental data that demonstrates the feasibility of fabricating a miniature nuclear particle dosimeter for monitoring doses in aircraft and satellites. The basic instrument is a Low Linear-Energy-Transfer (LET) Radiation Spectrometer (LoLRS) that is designed to measure the energy deposited by particles with low LET values. The heart of the instrument is a Silicon-Lithium Drifted Diode (SLDD). Test results show that the LoLRS can be used to monitor the radiation threat to personnel in flights of space- and aircraft and also to generate a comprehensive data base from aviation and satellite measurements that can contribute to the formulation of more accurate environmental radiation models for dose predictions with reduced uncertainty factors.

  1. Measuring Teachers and Learners' Perceptions of the Quality of Their Online Learning Experience

    Science.gov (United States)

    Gómez-Rey, Pilar; Barbera, Elena; Fernández-Navarro, Francisco

    2016-01-01

    This article explores the quality of the online learning experience based on the Sloan-C framework and the Online Learning Consortium's (OLC) quality scorecard. The OLC index has been implemented to evaluate quality in online programs from different perspectives. Despite this, the opinions of learners are ignored, and it is built using feedback…

  2. SCOOP: A Measurement and Database of Student Online Search Behavior and Performance

    Science.gov (United States)

    Zhou, Mingming

    2015-01-01

    The ability to access and process massive amounts of online information is required in many learning situations. In order to develop a better understanding of student online search process especially in academic contexts, an online tool (SCOOP) is developed for tracking mouse behavior on the web to build a more extensive account of student web…

  3. Formative evaluation: Developing measures for online family mental health recovery education.

    Science.gov (United States)

    Rue, Lisa A; Estrada, Samantha; Floren, Michael; MacKinnon, Krista

    2016-04-01

    Families facing mental health challenges have very limited access to ongoing support. A formative evaluation of Families Healing Together (FHT), a new online family mental health recovery program was conducted using five waves (N=108) of data. Exploratory factor analysis of the measures identified as important to the program theory found strong reliability evidence (α=.77-.86) for 6 constructs. A poor response rate (25%) did not allow for valid pre and postoutcome evaluation, however we did have enough information to assess the psychometric properties of the new measures. The new evaluation tool accounted for 34% of the variance in Capacity to Support Family Member, and nearly 50% of the variance in Hopefulness toward Recovery. New programs without existing measures require formative evaluation strategies that accurately describe program activities in order to develop outcome measures sensitive to novel aspects of program components. Most outcome measures are developed for individuals with mental health challenges not family members. These new measures may be beneficial to effectively evaluate programs that promote family recovery and wellness.

  4. Dose measurements using thermoluminescent dosimeters and DoseCal software at two paediatric hospitals in Rio de Janeiro

    Energy Technology Data Exchange (ETDEWEB)

    Mohamadain, K.E.M.; Azevedo, A.C.P.; Rosa, L.A.R. da E-mail: lrosa@ird.gov.br; Guebel, M.R.N.; Boechat, M.C.B

    2003-07-01

    A dosimetric survey in paediatric radiology is currently being carried out at the paediatric units of two large hospitals in Rio de Janeiro city: IPPMG (Instituto de Pediatria e Puericultura Martagao Gesteira, University Hospital of Federal University of Rio de Janeiro) and IFF (Instituto Fernandes Figueira, FIOCRUZ). Chest X-ray examination doses for AP, PA and LAT projections of paediatric patients have been obtained with thermoluminescent dosimeters (TLDs) and with use of a software package DoseCal. In IPPMG and IFF 100 patients have been evaluated with the use of the TLDs and another group of 100 patients with the DoseCal software. The aim of this work was to estimate the entrance skin dose (ESD) for frontal, back and lateral chest X-rays exposure of paediatric patients. For ESD evaluation, three different TL dosimeters have been used, namely LIF:Mg, Ti (TLD100), CaSO{sub 4}:Dy and LiF:Mg, Cu, P (TLD100H). The age intervals considered were 0-1, 1-5, 5-10 and 10-15 years. The results obtained with all dosimeters are similar, and it is in good agreement with the DoseCal software, especially for AP and PA projections. However, some larger discrepancies are presented for the LAT projection.

  5. Whole-body dose meters. Measurements of total activity. Ganzkoerperzaehler. Messungen der Gesamtaktivitaet

    Energy Technology Data Exchange (ETDEWEB)

    Koeppe, P. (Freie Univ. Berlin (Germany). Theoretische Strahlenkunde und Medizinische Informatik Klinikum Steglitz, Berlin (Germany). Bereich Ganzkoerperzaehler/Elektronenrechner)

    1990-04-01

    By means of measurements using a whole-body dose meter, the course of the incorporation of radionuclides was established between April 1986 and May 1989 for unchanged conditions of alimentation, activity-conscious alimentation, and uniquely increased incorporation. Monitoring covered persons from the most different spheres of life. The incorporation is compared with the one resulting from nuclear weapons explosions in the atmosphere. (DG).

  6. Using total beta-activity measurements in milk to derive thyroid doses from Chernobyl fallout.

    Science.gov (United States)

    Drozdovitch, V; Germenchuk, M; Bouville, A

    2006-01-01

    Following the Chernobyl accident, more than 200 childhood thyroid cancer cases have been observed in Brest Oblast of Belarus in territories slightly contaminated with 137Cs, but with suspected relatively high 131I fallout. The most helpful measurements available that can be used to estimate thyroid doses for the population of Brest Oblast are the total beta-activity measurements in cow's milk performed using DP-100 device within a few weeks after the accident. The 131I concentrations in milk were derived from the total beta-activity measurements on the basis of (1) a radioecological model used to estimate the variation with time of the radionuclide composition in milk and (2) the determination of the calibration factors of the DP-100 device for the most important radionuclides present in milk. As a result, 131I concentrations in milk were reconstructed for territories with different levels of 137Cs deposition. A non-linear dependence of the 131I concentration in milk on the 137Cs deposition density was obtained; it was used to estimate the thyroid doses from the consumption of 131I-contaminated cow's milk by the population of Brest Oblast. The average individual thyroid doses have been estimated to be 0.15, 0.18, 0.12, 0.06, 0.04 and 0.03 Gy for newborn, children aged 1, 5, 10 and 15 y and adults, respectively. The collective thyroid dose for the entire population of Brest Oblast is estimated to be 64,500 man Gy, the contribution from the adult population being about one half of the total. The methodology that is described could be applied in the framework of epidemiological studies of the relationship between radiation exposure to the thyroid gland and thyroid cancer in areas where numerous total beta-activity measurements in cow's milk were performed within a few weeks after the accident.

  7. A comparative study of three ionizing chambers for measurements of personal dose equivalent, Hp(10)

    Science.gov (United States)

    Oliveira, C.; Cardoso, J.; Silva, H.

    2015-11-01

    A comparative study of three ionization chambers which directly measure the quantity personal dose equivalent Hp(10), was performed. Results show that the ratio between the response (air kerma) determined by Monte Carlo and the experimental response (collected charge) normalized by the monitor unit is the same whatever is the chamber and that this ratio is proportional to the conversion coefficients for air kerma from photon fluence.

  8. Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

    Science.gov (United States)

    Morrell, B.; Okada, G.; Vahedi, S.; Koughia, C.; Edgar, A.; Varoy, C.; Belev, G.; Wysokinski, T.; Chapman, D.; Sammynaiken, R.; Kasap, S. O.

    2014-02-01

    Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm3+) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm3+-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm3+-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm2+ to Sm3+ reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm2+ to Sm3+ reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.

  9. Measurement of neutron dose equivalent outside and inside of the treatment vault of GRID therapy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xudong; Charlton, Michael A.; Esquivel, Carlos; Eng, Tony Y.; Li, Ying; Papanikolaou, Nikos [University of Texas Health Science Center, San Antonio, Texas 78229 (United States)

    2013-09-15

    Purpose: To evaluate the neutron and photon dose equivalent rates at the treatment vault entrance (H{sub n,D} and H{sub G}), and to study the secondary radiation to the patient in GRID therapy. The radiation activation on the grid was studied.Methods: A Varian Clinac 23EX accelerator was working at 18 MV mode with a grid manufactured by .decimal, Inc. The H{sub n,D} and H{sub G} were measured using an Andersson–Braun neutron REM meter, and a Geiger Müller counter. The radiation activation on the grid was measured after the irradiation with an ion chamber γ-ray survey meter. The secondary radiation dose equivalent to patient was evaluated by etched track detectors and OSL detectors on a RANDO{sup ®} phantom.Results: Within the measurement uncertainty, there is no significant difference between the H{sub n,D} and H{sub G} with and without a grid. However, the neutron dose equivalent to the patient with the grid is, on average, 35.3% lower than that without the grid when using the same field size and the same amount of monitor unit. The photon dose equivalent to the patient with the grid is, on average, 44.9% lower. The measured average half-life of the radiation activation in the grid is 12.0 (±0.9) min. The activation can be categorized into a fast decay component and a slow decay component with half-lives of 3.4 (±1.6) min and 15.3 (±4.0) min, respectively. There was no detectable radioactive contamination found on the surface of the grid through a wipe test.Conclusions: This work indicates that there is no significant change of the H{sub n,D} and H{sub G} in GRID therapy, compared with a conventional external beam therapy. However, the neutron and scattered photon dose equivalent to the patient decrease dramatically with the grid and can be clinical irrelevant. Meanwhile, the users of a grid should be aware of the possible high dose to the radiation worker from the radiation activation on the surface of the grid. A delay in handling the grid after the beam

  10. Natural gas large volumes measurement: going for on-line custody transfer; Medicao de grandes volumes de gas natural: rumo a transferencia de custodia on-line

    Energy Technology Data Exchange (ETDEWEB)

    Mercon, Eduardo G.; Frisoli, Caetano [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil)

    2005-07-01

    This paper describes the structure of the natural gas flow measurement process in TRANSPETRO, and comments features and performance of existing or under-implantation equipment and systems, reviewing best practices and technology in use. This process runs through three interrelated segments: data flow measurement, strictly speaking; data transfer and acquisition; and data flow measurement certification (data consolidation to invoice). Initially, the work makes an approach to the data flow measurement segment, evaluating technical features of flow meters, and describing configurations and functions of the operating gas flow computers in TRANSPETRO's custody transfer stations. In this part it will also be presented the implantation of TRANSPETRO's system for gas chromatography data input on-line to flow computers. Further, in data transfer and acquisition, SCADA system technical aspects will be evaluated, considering communications protocols and programmable logic controllers functions in remote terminal units, and discussing their places in the measurement process. Additionally, TRANSPETRO's experience in data measurement certification tools is in discussion, as well as new upcoming tools and their potential features, from what new practices will be suggested. Finally, all the work has been conceived and carried out always aiming to the state-of-the-art technology in gas flow measurement: on-line custody transfer. (author)

  11. SU-E-I-59: Image Quality and Dose Measurement for Partial Cone-Beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Abouei, E; Ford, N [University of British Columbia, Vancouver, BC (Canada)

    2014-06-01

    Purpose: To characterize performance of cone beam CT (CBCT) used in dentistry investigating quantitatively the image quality and radiation dose during dental CBCT over different settings for partial rotation of the x-ray tube. Methods: Image quality and dose measurements were done on a variable field of view (FOV) dental CBCT (Carestream 9300). X-ray parameters for clinical settings were adjustable for 2–10 mA, 60–90 kVp, and two optional voxel size values, but time was fixed for each FOV. Image quality was assessed by scanning cylindrical poly-methyl methacrylate (PMMA) image quality phantom (SEDENTEXCT IQ), and then the images were analyzed using ImageJ to calculate image quality parameters such as noise, uniformity, and contrast to noise ratio (CNR). A protocol proposed by SEDENTEXCT, dose index 1 (DI1), was applied to dose measurements obtained using a thimble ionization chamber and cylindrical PMMA dose index phantom (SEDENTEXCT DI). Dose distributions were obtained using Gafchromic film. The phantoms were positioned in the FOV to imitate a clinical positioning. Results: The image noise was 6–12.5% which, when normalized to the difference of mean voxel value of PMMA and air, was comparable between different FOVs. Uniformity was 93.5ß 99.7% across the images. CNR was 1.7–4.2 and 6.3–14.3 for LDPE and Aluminum, respectively. Dose distributions were symmetric about the rotation angle's bisector. For large and medium FOVs at 4 mA and 80–90 kVp, DI1 values were in the range of 1.26–3.23 mGy. DI1 values were between 1.01–1.93 mGy for small FOV (5×5 cm{sup 2}) at 4–5 mA and 75–84 kVp. Conclusion: Noise decreased by increasing kVp, and the CNR increased for each FOV. When FOV size increased, image noise increased and CNR decreased. DI1 values were increased by increasing tube current (mA), tube voltage (kVp), and/or FOV. Funding for this project from NSERC Discovery grant, UBC Faculty of Dentistry Research Equipment Grant and UBC Faculty of

  12. Effect of Medication Label Units of Measure on Parent Choice of Dosing Tool: A Randomized Experiment.

    Science.gov (United States)

    Yin, H Shonna; Parker, Ruth M; Sanders, Lee M; Dreyer, Benard P; Mendelsohn, Alan; Bailey, Stacy; Patel, Deesha A; Jimenez, Jessica J; Kim, Kwang-Youn A; Jacobson, Kara; Hedlund, Laurie; Landa, Rosa; Maness, Leslie; Tailor Raythatha, Purvi; McFadden, Terri; Wolf, Michael S

    Some experts recommend eliminating "teaspoon" and "tablespoon" terms from pediatric medication dosing instructions, because these terms could inadvertently encourage use of nonstandard tools (ie, kitchen spoons), which are associated with dosing errors. We examined whether use of "teaspoon" or "tsp" on prescription labels affects parents' choice of dosing tools, and the role of health literacy and language. Analysis of data collected as part of a controlled experiment (SAFE Rx for Kids [Safe Administration For Every Prescription for Kids] study), which randomized English- and Spanish-speaking parents (n = 2110) of children 8 years of age and younger to 1 of 5 groups, which varied in unit of measurement pairings on medication labels and dosing tools. Outcome assessed was parent self-reported choice of dosing tool. Parent health literacy was measured using the Newest Vital Sign. Seventy-seven percent had limited health literacy (36.0% low, 41.0% marginal); 35.0% completed assessments in Spanish. Overall, 27.7% who viewed labels containing either "tsp" or "teaspoon" units (alone or with "mL") chose nonstandard dosing tools (ie, kitchen teaspoon, kitchen tablespoon), compared with 8.3% who viewed "mL"-only labels (adjusted odds ratio [AOR] = 4.4 [95% confidence interval (CI), 3.3-5.8]). Odds varied based on whether "teaspoon" was spelled out or abbreviated ("teaspoon"-alone: AOR = 5.3 [95% CI, 3.8-7.3]); "teaspoon" with mL: AOR = 4.7 [95% CI, 3.3-6.5]; "tsp" with mL: AOR = 3.3 [95% CI, 2.4-4.7]; P units ("teaspoon" or "tsp") on prescription labels is associated with increased likelihood of parent choice of nonstandard dosing tools. Future studies might be helpful to examine the real-world effect of eliminating teaspoon units from medication labels, and identify additional strategies to promote the safe use of pediatric liquid medications. Copyright © 2016 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

  13. Measurement of neutron dose with an organic liquid scintillator coupled with a spectrum weight function

    Energy Technology Data Exchange (ETDEWEB)

    Kim, E.; Endo, A.; Yamaguchi, Y.; Yoshizawa, M.; Nakamura, T.; Shiomi, T

    2002-07-01

    A dose evaluation method for neutrons in the energy range of a few MeV to 100 MeV has been developed using a spectrum weight function (G-function), which is applied to an organic liquid scintillator of 12.7 cm in diameter and 12.7 cm in length. The G-function that converts the pulse height spectrum of the scintillator into the ambient dose equivalent, H*(10), was calculated by an unfolding method using successive approximation of the response function of the scintillator and the ambient dose equivalent per unit neutron fluence (H*(10) conversion coefficients) of ICRP 74. To verify the response function of the scintillator and the value of H*(10) evaluated by the G-function, pulse height spectra of the scintillator were measured in some different neutron fields, which have continuous energy, monoenergetic and quasi-monoenergetic spectra. Values of H*(10) estimated using the G-function and pulse height spectra of the scintillator were compared with those calculated using neutron energy spectra. These doses agreed with each other. From the results, it was concluded that H*(10) can be evaluated directly from the pulse height spectrum of the scintillator by applying the G-function proposed in this study. (author)

  14. Final report of evaluation of dose and measurement of radon concentration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    A mean annual exposure to radon daughters in indoor air was estimated on the basis of measurement of radon concentration in indoor air in Japan from fiscal 1992 to 1996. Doses were estimated by UNSCEAR method. The representative values in this report show the mean values in whole Japan. Each dose in the local area was different reflecting the different concentration of radon daughters. However, the same parameters were used in each area. When mean annual dose of radon daughters was estimated, we used 15.5 Bq m{sup -3} mean annual exposure to radon daughters in indoor air, 5 Bq m{sup -3} that in outdoor air, 0.4 the equilibrium factor indoor, 0.6 the equilibrium factor outdoor and 0.9 of P. The model of UNSCEAR based on these above values gave 0.46 mSv y{sup -1} mean annual dose of radon daughters which were consisted of from 0.38 mSv y{sup -1} in Kanto district to 0.52 mSv y{sup -1} Kyushu, Okinawa district. (S.Y.)

  15. Stored-fluorography mode reduces radiation dose during cardiac catheterization measured with OSLD dosimeter

    Science.gov (United States)

    Ting, Chien-Yi; Chen, Zhih-Cherng; Tang, Kuo-Ting; Liu, Wei-Chung; Lin, Chun-Chih; Wang, Hsin-Ell

    2015-12-01

    Coronary angiogram is an imperative tool for diagnosis of coronary artery diseases, in which cine-angiography is a commonly used method. Although the angiography proceeds under radiation, the potential risk of radiation exposure for both the patients and the operators was seldom noticed. In this study, the absorbed radiation dose in stored-fluorography mode was compared with that in cine-angiography mode by using optically simulated luminescent dosimeters to realize their effects on radiation dose. Patients received coronary angiogram via radial artery approach were randomized into the stored-fluorography group (N=30) or the cine-angiography group (N=30). The excluded criteria were: 1. women at pregnancy or on breast feeding, 2. chronic kidney diseases with glomerular filtration rate less than 60 mL/min. During the coronary angiogram, absorbed dose of the patients and the operator radiation exposure was measured with optically simulated luminescent dosimeter (OSLD). The absorbed dose of the patients in the stored-fluorography group (3.13±0.25 mGy) was apparently lower than that in the cine-angiography group (65.57±5.37 mGy; Pcine-angiography (0.6519μGy). Compared with traditional cine-angiography mode, the stored-fluorography mode can apparently reduce radiation exposure of the patients and the operator in coronary angiogram.

  16. Proton radiography and proton computed tomography based on time-resolved dose measurements

    Science.gov (United States)

    Testa, Mauro; Verburg, Joost M.; Rose, Mark; Min, Chul Hee; Tang, Shikui; Hassane Bentefour, El; Paganetti, Harald; Lu, Hsiao-Ming

    2013-11-01

    We present a proof of principle study of proton radiography and proton computed tomography (pCT) based on time-resolved dose measurements. We used a prototype, two-dimensional, diode-array detector capable of fast dose rate measurements, to acquire proton radiographic images expressed directly in water equivalent path length (WEPL). The technique is based on the time dependence of the dose distribution delivered by a proton beam traversing a range modulator wheel in passive scattering proton therapy systems. The dose rate produced in the medium by such a system is periodic and has a unique pattern in time at each point along the beam path and thus encodes the WEPL. By measuring the time dose pattern at the point of interest, the WEPL to this point can be decoded. If one measures the time-dose patterns at points on a plane behind the patient for a beam with sufficient energy to penetrate the patient, the obtained 2D distribution of the WEPL forms an image. The technique requires only a 2D dosimeter array and it uses only the clinical beam for a fraction of second with negligible dose to patient. We first evaluated the accuracy of the technique in determining the WEPL for static phantoms aiming at beam range verification of the brain fields of medulloblastoma patients. Accurate beam ranges for these fields can significantly reduce the dose to the cranial skin of the patient and thus the risk of permanent alopecia. Second, we investigated the potential features of the technique for real-time imaging of a moving phantom. Real-time tumor tracking by proton radiography could provide more accurate validations of tumor motion models due to the more sensitive dependence of proton beam on tissue density compared to x-rays. Our radiographic technique is rapid (˜100 ms) and simultaneous over the whole field, it can image mobile tumors without the problem of interplay effect inherently challenging for methods based on pencil beams. Third, we present the reconstructed p

  17. Measurement of personal dose equivalent of X and gamma radiation by ring dosimeter: Results of intercomparison measurements

    Directory of Open Access Journals (Sweden)

    Małgorzata Adamowicz

    2013-10-01

    Full Text Available Background: The aim of the study was to present the results of the interlaboratory comparisons for ring dosimeters and to confirm that the applied method is suitable for measuring the personal dose equivalent HP(0.07. In addition, calibration procedures used in dosimetric measurements in persons occupationally exposed to ionizing photon radiation X and γ were presented. Materials and Methods: Ring dosimeters made of flexible plastics with the diameter of approximately 20 mm, equipped with two thermoluminescence (TL detectors type MTS-N, were the subject of interlaboratory comparisons. Irradiated detectors were red out using a new manual TLD's reader (FIMEL, France. All TLD exposures were done for validation of TLD readers and were performed using the reference X-ray and γ beams with the ISO rod phantom. The methodology of performed exposures corresponded with the methods applied by the European Radiation Dosimetry Group (EURADOS, the European organizer of interlaboratory comparisons. Results: The energy, dose and angular characteristics of the ring dosimeter allowed to elaborate the formula for estimating and verifying the personal dose equivalent HP(0.07. The test was performed to check and confirm the correctness of the estimated characteristics. The test results were satisfactory, and thus the readiness to implement TLD reader in the used method and to participate in interlaboratory comparisons was confirmed. Conclusions: According to the requirements of the Polish Centre for Accreditation, the laboratory was participating in the interlaboratory comparison organized by EURADOS in terms of the personal dose equivalent HP(0.07. The result of the comparison was satisfactory, therefore the correctness of the testing procedure was confirmed. Med Pr 2013;64(5:631–637

  18. Calorimetry for dose measurement at electron accelerators in the 80-120 keV energy range

    DEFF Research Database (Denmark)

    Helt-Hansen, J.; Miller, A.; Duane, S.

    2005-01-01

    Calorimeters for dose measurement at low-energy electron accelerator energies (80-120 keV) are described. Three calorimeters with different characteristics were designed and their dose response and measurement uncertainties were characterized. The heated air between the beam exit window and the c...

  19. A comparative study for detection and measurement of voltage disturbance in online condition

    Directory of Open Access Journals (Sweden)

    Vijay Gajanan Neve

    2015-05-01

    Full Text Available Voltage disturbance is the most important power quality problem faced by many industrial customers. It includes voltage sag, swell, spikes and harmonics. Real time detection of these voltage disturbances posed various problems. This paper compares the various methods of detection of voltage sag and swells in real time on the basis of detection time, magnitude, effect of windowing and effect of sampling frequencies. The RMS, Peak, Fourier transform and Missing Voltage algorithm are introduced and discussed in them for real time implementation. Comparative analysis reveals that quantification of voltage sag and swell is possible using these measurements. The main focus is given on to these points and all the voltage sag and swell detection technique tested online with the help of advantech card data acquisition. The voltage sag and swell events are generated by using practical experimentation in laboratory.

  20. Identifying and Measuring Ill-Structured Problem Formulation and Resolution in Online Asynchronous Discussions

    Directory of Open Access Journals (Sweden)

    Elizabeth Murphy

    2004-02-01

    Full Text Available Abstract: This paper reports on a study involving the development and application of an instrument to identify and measure ill-structured problem formulation and resolution (PFR in online asynchronous discussions (OADs. The instrument was developed by first determining PFR processes relevant to ill-structured problems in professional practice. The processes were derived from a conceptual framework. Further refinement of the instrument was achieved by the addition of indicators of processes. These indicators are derived through application of the instrument to an actual discussion in which the processes are operationalized. Results of the application of the instrument indicated that participants engaged more in problem resolution than in problem formulation. The instrument can be further developed and refined through its application in other contexts by researchers or practitioners interested in the design and use of OADs.

  1. A layered modulation method for pixel matching in online phase measuring profilometry

    Science.gov (United States)

    Li, Hongru; Feng, Guoying; Bourgade, Thomas; Yang, Peng; Zhou, Shouhuan; Asundi, Anand

    2016-10-01

    An online phase measuring profilometry with new layered modulation method for pixel matching is presented. In this method and in contrast with previous modulation matching methods, the captured images are enhanced by Retinex theory for better modulation distribution, and all different layer modulation masks are fully used to determine the displacement of a rectilinear moving object. High, medium and low modulation masks are obtained by performing binary segmentation with iterative Otsu method. The final shifting pixels are calculated based on centroid concept, and after that the aligned fringe patterns can be extracted from each frame. After performing Stoilov algorithm and a series of subsequent operations, the object profile on a translation stage is reconstructed. All procedures are carried out automatically, without setting specific parameters in advance. Numerical simulations are detailed and experimental results verify the validity and feasibility of the proposed approach.

  2. Probability effects in anticipation investigated with online behavioural measures (mouse tracking)

    DEFF Research Database (Denmark)

    Bruhn, Pernille; Bærentsen, Klaus B.

    -hoc behavioural measures of the anticipatory processes involved. Methods: The present study investigates how knowledge of probability affects real-time anticipatory processes. Behaviour is monitored online by tracking the computer mouse trajectory leading to a required response (mouse-click on Target......). The paradigm implements a probability structure that allows the participant to gain knowledge about the relative probability of the occurrence of two alternative events (target occurring at left or right side). Results: Preliminary results indicate that knowledge of probability affects both RT and mouse...... movement; both vary systematically over 4 probability conditions (100, 80, 50 and 20 %), with lower RT and mouse movements displaying more direct trajectory to the target in high probability trials....

  3. Emotional Reactions and the Pulse of Public Opinion: Measuring the Impact of Political Events on the Sentiment of Online Discussions

    CERN Document Server

    Gonzalez-Bailon, Sandra; Kaltenbrunner, Andreas

    2010-01-01

    This paper analyses changes in public opinion by tracking political discussions in which people voluntarily engage online. Unlike polls or surveys, our approach does not elicit opinions but approximates what the public thinks by analysing the discussions in which they decide to take part. We measure the emotional content of online discussions in three dimensions (valence, arousal and dominance), paying special attention to deviation around average values, which we use as a proxy for disagreement and polarisation. We show that this measurement of public opinion helps predict presidential approval rates, suggesting that there is a point of connection between online discussions (often deemed not representative of the overall population) and offline polls. We also show that this measurement provides a deeper understanding of the individual mechanisms that drive aggregated shifts in public opinion. Our data spans a period that includes two US presidential elections, the attacks of September 11, and the start of mi...

  4. Measurements of spatial distribution of absorbed dose in proton therapy with Gafchromic EBT3

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Regazzoni, V.; Grisotto, S.; Artuso, E.; Giove, D. [Universita degli Studi di Milano, Department of Physics, via Celoria 16, 20133 Milano (Italy); Borroni, M.; Carrara, M.; Pignoli, E. [Fondazione IRCCS, Istituto Nazionale dei Tumori di Milano, Medical Physics Unit, via Giacomo Venezian 16, 20133 Milano (Italy); Mirandola, A.; Ciocca, M., E-mail: grazia.gambarini@mi.infn.it [Centro Nazionale Adroterapia Oncologica, Medical Physics Unit, Strada Campeggi 53, 27100 Pavia (Italy)

    2014-08-15

    A study of the response of EBT3 films has been carried out. Light transmittance images (around 630 nm) were acquired by means of a Ccd camera. The difference of optical density was assumed as dosimeter response. Calibration was performed by means of {sup 60}Co photons, at a radiotherapy facility. A study of the response variation during the time after exposure has been carried out. EBT3 films were exposed, in a solid-water phantom, to proton beams of various energies and the obtained depth-dose profiles were compared with those measured with a ionization chamber. As expected, in the Bragg peak region the values obtained with EBT3 films were lower than those obtained with the ionization chamber. The ratio of such values was evaluated, along dose profiles, for each utilized energy. A method for correcting the data measured with EBT3 has been proposed and tested. The results confirm that the method can be advantageously applied for obtaining spatial distribution of the absorbed dose in proton therapy. (author)

  5. Measurement of eye lens dose for Varian On-Board Imaging with different cone-beam computed tomography acquisition techniques

    Directory of Open Access Journals (Sweden)

    Sudesh Deshpande

    2016-01-01

    Full Text Available The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT acquisition protocols of Varian′s On-Board Imaging (OBI system using optically stimulated luminescence dosimeter (OSLD and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was placed on the patient between the eyebrows of both eyes in line of nose during CBCT image acquisition to measure eye lens doses. The eye lens dose measurements were carried out for three different cone-beam acquisition protocols (standard dose head, low-dose head [LDH], and high-quality head [HQH] of Varian OBI. Measured doses were correlated with patient geometry and distance between isocenter and eye lens. Measured eye lens doses for standard head and HQH protocols were in the range of 1.8-3.2 mGy and 4.5-9.9 mGy, respectively. However, the measured eye lens dose for the LDH protocol was in the range of 0.3-0.7 mGy. The measured data indicate that eye lens dose to patient depends on the selected imaging protocol. It was also observed that eye lens dose does not depend on patient geometry but strongly depends on distance between eye lens and treatment field isocenter. However, undoubted advantages of imaging system should not be counterbalanced by inappropriate selection of imaging protocol, especially for very intense imaging protocol.

  6. Peripheral dose measurement in breast cancer patients submitted to Tomotherapy using thermoluminescent dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Medina A, O.; Medrano S, A. C.; Azorin N, J. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Mora G, L. C., E-mail: omedina@xanum.uam.mx [IMSS, Centro Medico Nacional Siglo XXI, Av. Cuauhtemoc 330, 06725 Mexico D. F. (Mexico)

    2015-10-15

    Full text: Thermoluminescence dosimetry (TLD) has been one of the most important techniques in medical radiation applications over many years, creating opportunities of advancing in novel radiotherapy techniques particularly in Tomotherapy with photons. LiF:Mg,Ti TLD is one kind of TLD which can be used in Tomotherapy because of having suitable properties such as good sensitivity, small size and tissue equivalence. Hypo fractionation is a radiotherapeutic technique, widely accepted as an important treatment for breast cancer patients, characterized by high doses at which they are exposed for treatment of cancerous tumors that are irradiated precisely with photons from a helical accelerator and aims to decrease the number of sessions from 3 - 6 weeks to 1 - 3 weeks. Results of measuring the peripheral dose (Pd) in breast cancer patients submitted to Tomotherapy with high-energy photons are presented. (Author)

  7. Optimisation need of dental radiodiagnostic procedures: results of effective dose evaluation from Rando phantom measurements

    Energy Technology Data Exchange (ETDEWEB)

    Borio, R.; Chiocchini, S.; Cicioni, R.; Degli Esposti, P.; Rongoni, A.; Sabatini, P.; Saetta, D.M.S. (Perugia Univ. (Italy). Health Physics Lab. Istituto Nazionale di Fisica Nucleare, Perugia (Italy)); Regi, L.; Caprino, G. (Perugia Univ. (Italy). Dept. of Radiology)

    1994-01-01

    Radiological examinations of different types are needed in dental practice both to make a correct diagnosis and to carry out an adequate therapy. Particularly in orthodentic practices, because of the youth of the majority of the patients, an assessment of the detriment to health (through the effective dose equivalent) caused by medical diagnostic exposure to ionising radiation is needed to make decisions about the optimisation of dental radiodiagnostic procedures. Experimental data from measurements on a Rando phantom were collected for the radiological examinations required for dental and for orthodontic practices (with and without protective apron and collar). The results show the effectiveness of the leaded apron and collar in all the examinations carried out, particularly in reducing thyroid dose. (author).

  8. Use of silicon photodiode optically connected to scintillator in measurement of gamma dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Gilar, O. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky); Petr, I. (Ceske Vysoke Uceni Technicke, Prague (Czechoslovakia). Fakulta Jaderna a Fysikalne Inzenyrska)

    1984-06-01

    Contributing to the signal which is produced in the photodiode by direct interaction with radiation may also be light photons produced by scintillation in the scintillator which is in optical contact with the photodiode. The scintillator/photodiode combination may increase sensitivity in comparison with the photodiode alone. The energy dependence of the detector will change according to the scintillator material and size. The configuration is described of a detector with CsI(Tl) scintillator. The detector is suitable for medium and large dose rates, the limiting factor for measuring small dose rates is the intensity of the photodiode dark current and its temperature dependence. A higher sensitivity of the designed detector configuration may be achieved by selecting a scintillator with a more suitable emission spectrum or by technological modifications of the photodiode.

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

    CERN Document Server

    Job, P K; Semones, E

    1999-01-01

    High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mmx300 mmx300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cro...

  10. Ionizing radiation fluxes and dose measurements during the Kosmos 1887 satellite flight.

    Science.gov (United States)

    Charvat, J; Spurny, F; Kopecka, B; Votockova, I

    1990-01-01

    The results of dosimetric experiments performed during the flight of Kosmos 1887 biosatellite are presented. Two kinds of measurements were performed on the external surface of the satellite. First, the fluences and spectra of low energy charged particles were established. It was found that most of the particles registered by means of solid state nuclear track detectors are helium nuclei. Tracks of oxygen nuclei and some heavier charged particles were also observed. Thermoluminescent detectors were used to establish absorbed doses in open space on the satellite's surface and behind thin shielding. It was found that these doses were rather high; nevertheless, their decrease with shielding thickness is very rapid. Dosimetric and other consequences of the results obtained are analyzed and discussed.

  11. High precision measurements of arsenic and phosphorous implantation dose in silicon by secondary ion mass spectrometry

    CERN Document Server

    Chi, P H; McKinley, J M; Stevie, F A; Granger, C N

    2002-01-01

    The metrology section of the 1999 International Technology Roadmap for Semiconductors specifies in-line dopant profile concentration precision requirements ranging from a value of 5% in 1999 to a value of 2% in 2008. These values are to be accomplished with ''low systematic error.'' Secondary ion mass spectrometry (SIMS) has demonstrated the capability to meet these requirements for B, As, and P. However, the detailed analytical protocols required to achieve these goals have not been completely specified. This article reports the parameters that must be controlled to make highly repeatable dose measurements of As and P implants in Si with magnetic sector SIMS instruments. Instrument conditions that were investigated include analytical species, matrix ion species, energy bandpass, and sample holder design. With optimized settings, we demonstrate the ability to distinguish As or P implant doses differing by 5%.

  12. On-line measurement of mechanical, optical properties and roughness parameters

    Directory of Open Access Journals (Sweden)

    Hartman, H.

    2005-12-01

    Full Text Available On-line measurements become a central importance for the control of production line output. The target is to replace traditional single local destructive quality checks by a continuous survey of the product properties. Other traditional like pyrometric temperature measurements suffer of well-known but non-soluble weakness points. New methods need the unambiguous correlation with the results of traditional testing to be representative for valid proof standards.EKO Stahl GmbH introduces several methods of on-line measurements focused actually on temperature measurement means of FTIR-Spectrometer, prediction of the mechanical properties of steel strips using the information of residual magnetization after a magnetization pulse and optical roughness measurements. The correlation between the results of the new methods and the classical proof processes has been established in a satisfactory manner.

    Las medidas on line van tomando una importancia central para el control de la calidad de la producción . El objetivo es reemplazar las pruebas destructivas puntuales tradicionales por un control continuo de las características del producto. Otros métodos tradicionales, como la medida de la temperatura con pirómetros, adolecen de conocidos pero insolubles puntos débiles. Los nuevos métodos necesitan la correlación inequívoca con los resultados de los métodos corrientes clásicos para obtener la autoridad de un estándar de prueba. La EKO Stahl GmbH ha introducido varios métodos de medidas on line y actualmente concentrados en la medida de la temperatura con espectrómetro FTIR, predicción de las características mecánicas usando la información del magnetismo residual, a partir de un impulso magnético inicial así como la medida óptica de la rugosidad. La correlación entre los resultados de los nuevos métodos y los métodos clásicos ha quedado establecida de manera satisfactoria.

  13. On-line field measurements of VOC emissions from a spruce tree at SMEAR Estonia

    Science.gov (United States)

    Bourtsoukidis, Efstratios; Bonn, Boris; Noe, Steffen

    2013-04-01

    We have investigated VOC emissions from a Norway spruce tree (Picea abies) in a hemi-boreal mixed forest in September and October 2012, using Proton Transfer Reaction Mass Spectrometry and Gas Chromatography - Mass Spectrometry techniques, applied in a dynamic branch enclosure system that was automatically operated with an electrical compressor. Parallel to BVOC measurements a vast amount of atmospheric (CO2, CH4, H2O, CO, particles) and meteorological (temperature, relative humidity, photosynthetic active radiation, wind speed and direction, precipitation) parameters were measured in the ambient atmosphere and inside the cuvette enclosure (temperature, relative humidity, O3). Prior to the measuring period, an innovatory experimental setup was built at Järvselja forest station, in order to accomplish the detection of BVOC and minimize sampling losses. Therefore, a new inlet line, consisting of 19.4m of heated and isolated glass tube was constructed. The new inlet system applied, allowed the on-line detection and calculation of sesquiterpene (SQT) emission rates for the first time in a hemi-boreal forest site. It total, 12 atmospheric relevant BVOCs were continuously monitored for a three week period and the emission rates were derived. Along with diurnal profiles and continuous timeless, some interesting observations showed the possibility of ozone effect on SQT emissions, the possibility of radiation effect on MT emissions, the higher induced emissions due to mechanical stress and the possibility for a valid intercomparison between different spruce trees located in mountain Kleiner Feldberg (Germany) and in Järvseja forest station (Estonia).

  14. The Corrosion Inhibition Characteristics of Sodium Nitrite Using an On-line Corrosion Rate Measurement System

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mal-Yong; Kang, Dae-Jin [Korea Polytechnic University, Shiheung (Korea, Republic of); Moon, Jeon-Soo [Future Technology Research Laboratory, KEPCO Research Institute, Daejeon (Korea, Republic of)

    2015-04-15

    An on-line corrosion rate measurement system was developed using a personal computer, a data acquisition board and program, and a 2-electrode corrosion probe. Reliability of the developed system was confirmed with through comparison test. With this system, the effect of sodium nitrite (NaNO{sub 2}) as a corrosion inhibitor were studied on iron and aluminum brass that were immersed in sodium chloride (NaCl) solution. Corrosion rate was measured based on the linear polarization resistance method. The corrosion rates of aluminum brass and iron in 1% NaCl solutions were measured to be 0.290 mm per year (mmpy) and 0.2134 mmpy, respectively. With the addition of 200 ppm of NO{sub 2}{sup -}, the corrosion rates decreased to 0.0470 mmpy and 0.0254 mmpy. The addition of NO{sub 2}{sup -} caused a decrease in corrosion rates of both aluminum brass and iron, yet the NO{sub 2}{sup -} acted as a more effective corrosion inhibitor for iron. than aluminum brass.

  15. On-line non-intrusive particle size measurement of pulverised fuel through digital imaging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents the basic principles of particle size measurement and latest industrial results recorded using an innovative optical instrumentation system designed to measure the size distribution of particles in a pneumatic suspension. The system is non-intrusive and cost-effective. A low-cost CCD camera is used to capture images of the particulate flow field, which is illuminated by a low-cost pulsed laser sheet generator. The particle size distribution is then determined by processing the particle images through the use of novel processing algorithms. Experimental results obtained in the past on a small scale particle flow test rig have demonstrated that the system is capable of measuring the size distribution of pneumatically conveyed particles with an accuracy of a few percent. For the present paper results obtained when testing the system at a 4 MW industrial test facility are presented. Comparisons are made with both off-line reference data achieved through sieving and on-line laser diffraction data recorded using an intrusive, extractive, Malvern Instruments system. In general there is good agreement between results when considering the characteristics and limitations of the individual methodologies. The novel imaging system shows itself to be rugged, practical and useful under genuine industrial conditions.

  16. Statistical methods to evaluate the correlation between measured and calculated dose using quality assurance method in IMRT

    Directory of Open Access Journals (Sweden)

    Abdulhamid Chaikh

    2015-12-01

    Full Text Available Purpose: the objective of this study is to validate a procedure based on a statistical method to assess the agreement and the correlation between measured and calculated dose in the process of quality assurance (QA for Intensity-Modulated Radiation Therapy (IMRT.Patients and methods: 10 patients including 56 fields for head and neck cancer treatment were analyzed. For each patient, one treatment plan was generated using Eclipse TPS®. To compare the calculated dose with measured dose a CT-scan of solid water slabs (30 × 30 × 15 cm3 was used. The measurements were done for absolute dose by a pinpoint ionization chamber and 2D dose distributions using electronic portal imaging device dosimetry. Six criteria levels were applied for each case (3%, 3 mm, (4%, 3 mm, (5%, 3 mm, (4%, 4 mm, (5%, 4 mm and (5%, 5 mm. The normality of the data and the variance homogeneity were tested using Shapiro-Wilks test and Levene’s test, respectively. Wilcoxon signed-rank paired test was used to calculate p-value. Bland-Altman method was used to calculate the limit of agreement between calculated and measured doses and to draw a scatter plot. The correlation between calculated and measured doses was assessed using Spearman’s rank test.Results: The statistical tests indicate that the data do not fulfill normal distribution, p < 0.001 and had a homogenous variance, p = 0.85. The upper and lower limit of agreements for absolute dose measurements were 6.44% and -6.40%, respectively. Wilcoxon test indicated a significance difference between calculated and measured dose with ionization chamber, p = 0.01. Spearman’s test indicated a strong correlation between calculated and absolute measured dose, ρ = 0.99. Therefore, there is a lack of correlation between dose difference for absolute dose measurements and gamma passing rates for 2D dose measurements.Conclusion: the statistical tests showed that the common acceptance criteria’s using gamma evaluation are not able

  17. A comparison of emission calculations using different modeled indicators with 1-year online measurements.

    Science.gov (United States)

    Lengers, Bernd; Schiefler, Inga; Büscher, Wolfgang

    2013-12-01

    The overall measurement of farm level greenhouse gas (GHG) emissions in dairy production is not feasible, from either an engineering or administrative point of view. Instead, computational model systems are used to generate emission inventories, demanding a validation by measurement data. This paper tests the GHG calculation of the dairy farm-level optimization model DAIRYDYN, including methane (CH₄) from enteric fermentation and managed manure. The model involves four emission calculation procedures (indicators), differing in the aggregation level of relevant input variables. The corresponding emission factors used by the indicators range from default per cow (activity level) emissions up to emission factors based on feed intake, manure amount, and milk production intensity. For validation of the CH₄ accounting of the model, 1-year CH₄ measurements of an experimental free-stall dairy farm in Germany are compared to model simulation results. An advantage of this interdisciplinary study is given by the correspondence of the model parameterization and simulation horizon with the experimental farm's characteristics and measurement period. The results clarify that modeled emission inventories (2,898, 4,637, 4,247, and 3,600 kg CO₂-eq. cow(-1) year(-1)) lead to more or less good approximations of online measurements (average 3,845 kg CO₂-eq. cow(-1) year(-1) (±275 owing to manure management)) depending on the indicator utilized. The more farm-specific characteristics are used by the GHG indicator; the lower is the bias of the modeled emissions. Results underline that an accurate emission calculation procedure should capture differences in energy intake, owing to milk production intensity as well as manure storage time. Despite the differences between indicator estimates, the deviation of modeled GHGs using detailed indicators in DAIRYDYN from on-farm measurements is relatively low (between -6.4% and 10.5%), compared with findings from the literature.

  18. Increasing of MERARG experimental performances: on-line fission gas release measurement by mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Pontillon, Y.; Capdevila, H.; Clement, S. [CEA, DEN, DEC, SA3C, LAMIR, F-13108 Saint Paul lez Durance, (France); Guigues, E.; Janulyte, A.; Zerega, Y.; Andre, J. [Aix-Marseille Universite, LISA EA 4672, 13397 MARSEILLE cedex 20, (France)

    2015-07-01

    The MERARG device - implemented at the LECASTAR Hot Laboratory, at the CEA Cadarache - allows characterizing nuclear fuels with respect to the behaviour of fission gases during thermal transients representative of normal or off normal operating nuclear power plant conditions. The fuel is heated in order to extract a part or the total gas inventory it contains. Fission Gas Release (FGR) is actually recorded by mean of both on-line gamma spectrometry station and micro gas chromatography. These two devices monitor the quantity and kinetics of fission gas release rate. They only address {sup 85}Kr radioactive isotope and the elemental quantification of Kr, Xe and He (with a relatively low detection limit in the latter case, typically 5-10 ppm). In order to better estimate the basic mechanisms that promote fission gas release from irradiated nuclear fuels, the CEA fuel study department decided to improve its experimental facility by modifying MERARG to extend the studies of gamma emitter fission gases to all gases (including Helium) with a complete isotopic distribution capability. To match these specifications, a Residual Gas Analyser (RGA) has been chosen as mass spectrometer. This paper presents a review of the main aspects of the qualification/calibration phase of the RGA type analyser. In particular, results recorded over three mass ranges 1-10 u, 80-90 u and 120-140 u in the two classical modes of MERARG, i.e. on-line and off-line measurements are discussed. Results obtained from a standard gas bottle show that the quantitative analysis at a few ppm levels can be achieved for all isotopes of Kr and Xe, as well as masses 2 and 4 u. (authors)

  19. Light scattering and transmission measurement using digital imaging for online analysis of constituents in milk

    Science.gov (United States)

    Jain, Pranay; Sarma, Sanjay E.

    2015-05-01

    Milk is an emulsion of fat globules and casein micelles dispersed in an aqueous medium with dissolved lactose, whey proteins and minerals. Quantification of constituents in milk is important in various stages of the dairy supply chain for proper process control and quality assurance. In field-level applications, spectrophotometric analysis is an economical option due to the low-cost of silicon photodetectors, sensitive to UV/Vis radiation with wavelengths between 300 - 1100 nm. Both absorption and scattering are witnessed as incident UV/Vis radiation interacts with dissolved and dispersed constituents in milk. These effects can in turn be used to characterize the chemical and physical composition of a milk sample. However, in order to simplify analysis, most existing instrument require dilution of samples to avoid effects of multiple scattering. The sample preparation steps are usually expensive, prone to human errors and unsuitable for field-level and online analysis. This paper introduces a novel digital imaging based method of online spectrophotometric measurements on raw milk without any sample preparation. Multiple LEDs of different emission spectra are used as discrete light sources and a digital CMOS camera is used as an image sensor. The extinction characteristic of samples is derived from captured images. The dependence of multiple scattering on power of incident radiation is exploited to quantify scattering. The method has been validated with experiments for response with varying fat concentrations and fat globule sizes. Despite of the presence of multiple scattering, the method is able to unequivocally quantify extinction of incident radiation and relate it to the fat concentrations and globule sizes of samples.

  20. Development of an on-line radiation detection and measurements laboratory course

    Science.gov (United States)

    Kopp, Derick G.

    An on-line radiation detection and measurements lab is being developed with a grant from the U.S. Nuclear Regulatory Commission. The on-line laboratory experiments are designed to provide a realistic laboratory experience and will be offered to students at colleges/universities where such a course is not offered. This thesis presents four web-based experiments: 1) nuclear electronics, 2) gamma-ray spectroscopy with scintillation detectors, 3) gamma-ray attenuation in matter and external dosimetry, and 4) alpha spectroscopy and absorption in matter. The students access the experiments through a broad-band internet connection. Computer-controlled instrumentation developed in National Instruments (NI) LabVIEW(TM) communicates with the URSA-II (SE International, Inc.) data acquisition system, which controls the detector bias voltage, pulse shaping, amplifier gain, and ADC. Detector and amplifier output pulses can be displayed with other instrumentation developed in LabVIEW(TM) for the digital oscilloscope (USB-5132, NI). Additional instrumentation developed in LabVIEW(TM) is used to control the positions of all sources with stepper motor controllers (VXM-1, Velmex, Inc.) and to adjust pressure in the alpha chamber with a digital vacuum regulator (Model 200, J-KEM, Inc.). Unique interactive interfaces are created by integrating all of the necessary instrumentation to conduct each lab. These interfaces provide students with seamless functionality for data acquisition, experimental control, and live data display with real-time updates for each experiment. A webcam is set up to stream the experiment live so the student can observe the physical instruments and receive visual feedback from the system in real time.

  1. A Comparison of Model Calculation and Measurement of Absorbed Dose for Proton Irradiation. Chapter 5

    Science.gov (United States)

    Zapp, N.; Semones, E.; Saganti, P.; Cucinotta, F.

    2003-01-01

    With the increase in the amount of time spent EVA that is necessary to complete the construction and subsequent maintenance of ISS, it will become increasingly important for ground support personnel to accurately characterize the radiation exposures incurred by EVA crewmembers. Since exposure measurements cannot be taken within the organs of interest, it is necessary to estimate these exposures by calculation. To validate the methods and tools used to develop these estimates, it is necessary to model experiments performed in a controlled environment. This work is such an effort. A human phantom was outfitted with detector equipment and then placed in American EMU and Orlan-M EVA space suits. The suited phantom was irradiated at the LLUPTF with proton beams of known energies. Absorbed dose measurements were made by the spaceflight operational dosimetrist from JSC at multiple sites in the skin, eye, brain, stomach, and small intestine locations in the phantom. These exposures are then modeled using the BRYNTRN radiation transport code developed at the NASA Langley Research Center, and the CAM (computerized anatomical male) human geometry model of Billings and Yucker. Comparisons of absorbed dose calculations with measurements show excellent agreement. This suggests that there is reason to be confident in the ability of both the transport code and the human body model to estimate proton exposure in ground-based laboratory experiments.

  2. Gamma radiation measurements and dose rates in commercially-used natural tiling rocks (granites)

    CERN Document Server

    Tzortzis, M; Christofides, S; Christodoulides, G

    2003-01-01

    The gamma radiation in samples of a variety of natural tiling rocks (granites) imported in Cyprus for use in the building industry was measured, employing high-resolution gamma-ray spectroscopy. The rock samples were pulverized, sealed in 1 litre plastic Marinelli beakers, and measured in the laboratory with a live-time between 10 and 14 hours each. From the measured gamma-ray spectra, activity concentrations were determined for Th-232 (range from 1 to 906 Bq/kg), U-238 (from 1 to 588 Bq/kg) and K-40 (from 50 to 1606 Bq/kg). Elemental concentrations mean values of (35.2 +- 8.4) ppm, (6.2 +- 1.8) ppm and (4.0 +- 0.2) % were deduced, for thorium, uranium and potassium, respectively. The total absorbed dose rates in air calculated from the concentrations of the three radionuclides, Th-232 and U-238 series and K-40, ranged from 7 to 1209 nGy/h for full utilization of the materials, from 4 to 605 nGy/h for half utilization and from 2 to 302 nGy/h for one quarter utilization. The total effective dose rates per pers...

  3. Preliminary comparison of dose measurements on CRRES to NASA model predictions

    Energy Technology Data Exchange (ETDEWEB)

    Gussenhoven, M.S.; Mullen, E.G.; Brautigan, D.H. (Phillips Lab., Geophysics Directorate, Hanscom AFB, MA (US)); Holeman, E. (Boston Univ., MA (United States). Dept. of Physics); Jordan, C. (Radex Inc., Bedford, MA (US)); Hanser, F.; Dichter, B. (Panametrics, Inc., Waltham, MA (United States))

    1991-12-01

    In this paper, measurements of proton and electron dose from the space radiation dosimeter on the CRRES satellite, in a 18.1{degrees}, 350 km by 33000 km orbit, are compared to the NASA models for solar maximum conditions. Up to the time of the large, solar-initiated particle events near the end of March 1991, the results are similar to those previously reported for solar minimum at low altitudes. That is, prior to the March event, there is excellent agreement between model and measured values for protons and poor agreement for electrons. During the event period a second proton belt was formed at higher altitudes which is not contained in the proton models, and the electrons increased over an order of magnitude for the CRRES orbit. This resulted in poorer agreement between model and measured values for protons during and after the solar proton event and better agreement for electrons during the electron enhancement period. What the data show is that, depending on orbit, both the existing proton and electron models can give large errors in dose that can compromise space system performance and lifetime.

  4. Preliminary comparison of dose measurements on crres to NASA model predictions. (Reannouncement with new availability information)

    Energy Technology Data Exchange (ETDEWEB)

    Gussenhoven, M.S.; Mullen, E.G.; Brautigam, D.H.; Holeman, E.; Jordon, C.

    1991-12-01

    Measurements of proton and electron dose from the space radiation dosimeter on the CRRES satellite, in a 18.1 deg, 350 km by 33000km orbit, are compared to the NASA models for solar maximum conditions. Up to the time of the large, solar-initiated particle events near the end of March 1991, the results are similar to those previously reported for solar minimum at low altitudes. That is, prior to the March event, there is excellent agreement between model and measured values for protons and poor agreement for electrons. During the event period a second proton belt was formed at higher altitudes which is not contained in the proton models, and the electrons increased over an order of magnitude for the CRRES orbit. This resulted in poorer agreement between model and measured values for protons during and after the solar proton event and better agreement for electrons during the electron enhancement period. What the data show is that, depending on orbit, both the existing proton and electron models can give large errors in dose that can compromise space system performance and lifetime.

  5. Effects of measurement strategy and statistical analysis on dose-response relations between physical workload and low back pain

    OpenAIRE

    Jansen, Justin; Burdorf, Alex

    2003-01-01

    textabstractBACKGROUND: In epidemiological studies on physical workloads and back complaints, among the important features in modelling dose-response relations are the measurement strategy of the exposure and the nature of the dose-response relation that is assumed. AIM: To evaluate the effect of these two features on the strength of the dose-response relation between physical load and severe low back pain. METHODS: The study population consisted of 769 workers in nursing homes and homes for ...

  6. Estimating Effective Dose from Phantom Dose Measurements in Atrial Fibrillation Ablation Procedures and Comparison of MOSFET and TLD Detectors in a Small Animal Dosimetry Setting

    Science.gov (United States)

    Anderson-Evans, Colin David

    Two different studies will be presented in this work. The first involves the calculation of effective dose from a phantom study which simulates an atrial fibrillation (AF) ablation procedure. The second involves the validation of metal-oxide semiconducting field effect transistors (MOSFET) for small animal dosimetry applications as well as improved characterization of the animal irradiators on Duke University's campus. Atrial Fibrillation is an ever increasing health risk in the United States. The most common type of cardiac arrhythmia, AF is associated with increased mortality and ischemic cerebrovascular events. Managing AF can include, among other treatments, an interventional procedure called catheter ablation. The procedure involves the use of biplane fluoroscopy during which a patient can be exposed to radiation for as much as two hours or more. The deleterious effects of radiation become a concern when dealing with long fluoroscopy times, and because the AF ablation procedure is elective, it makes relating the risks of radiation ever more essential. This study hopes to quantify the risk through the derivation of dose conversion coefficients (DCCs) from the dose-area product (DAP) with the intent that DCCs can be used to provide estimates of effective dose (ED) for typical AF ablation procedures. A bi-plane fluoroscopic and angiographic system was used for the simulated AF ablation procedures. For acquisition of organ dose measurements, 20 diagnostic MOSFET detectors were placed at selected organs in a male anthropomorphic phantom, and these detectors were attached to 4 bias supplies to obtain organ dose readings. The DAP was recorded from the system console and independently validated with an ionization chamber and radiochromic film. Bi-plane fluoroscopy was performed on the phantom for 10 minutes to acquire the dose rate for each organ, and the average clinical procedure time was multiplied by each organ dose rate to obtain individual organ doses. The

  7. Radioactivity determination of sealed pure beta-sources by surface dose measurements and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chang Heon [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Jung, Seongmoon [Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul (Korea, Republic of); Choi, Kanghyuk; Son, Kwang-Jae; Lee, Jun Sig [Hanaro Applications Research, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ye, Sung-Joon, E-mail: sye@snu.ac.kr [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul (Korea, Republic of); Center for Convergence Research on Robotics, Advance Institutes of Convergence Technology, Seoul National University, Suwon (Korea, Republic of)

    2016-04-21

    This study aims to determine the activity of a sealed pure beta-source by measuring the surface dose rate using an extrapolation chamber. A conversion factor (cGy s{sup −1} Bq{sup −1}), which was defined as the ratio of surface dose rate to activity, can be calculated by Monte Carlo simulations of the extrapolation chamber measurement. To validate this hypothesis the certified activities of two standard pure beta-sources of Sr/Y-90 and Si/P-32 were compared with those determined by this method. In addition, a sealed test source of Sr/Y-90 was manufactured by the HANARO reactor group of KAERI (Korea Atomic Energy Research Institute) and used to further validate this method. The measured surface dose rates of the Sr/Y-90 and Si/P-32 standard sources were 4.615×10{sup −5} cGy s{sup −1} and 2.259×10{sup −5} cGy s{sup −1}, respectively. The calculated conversion factors of the two sources were 1.213×10{sup −8} cGy s{sup −1} Bq{sup −1} and 1.071×10{sup −8} cGy s{sup −1} Bq{sup −1}, respectively. Therefore, the activity of the standard Sr/Y-90 source was determined to be 3.995 kBq, which was 2.0% less than the certified value (4.077 kBq). For Si/P-32 the determined activity was 2.102 kBq, which was 6.6% larger than the certified activity (1.971 kBq). The activity of the Sr/Y-90 test source was determined to be 4.166 kBq, while the apparent activity reported by KAERI was 5.803 kBq. This large difference might be due to evaporation and diffusion of the source liquid during preparation and uncertainty in the amount of weighed aliquot of source liquid. The overall uncertainty involved in this method was determined to be 7.3%. We demonstrated that the activity of a sealed pure beta-source could be conveniently determined by complementary combination of measuring the surface dose rate and Monte Carlo simulations.

  8. Word knowledge in the crowd: Measuring vocabulary size and word prevalence in a massive online experiment.

    Science.gov (United States)

    Keuleers, Emmanuel; Stevens, Michaël; Mandera, Paweł; Brysbaert, Marc

    2015-01-01

    We use the results of a large online experiment on word knowledge in Dutch to investigate variables influencing vocabulary size in a large population and to examine the effect of word prevalence-the percentage of a population knowing a word-as a measure of word occurrence. Nearly 300,000 participants were presented with about 70 word stimuli (selected from a list of 53,000 words) in an adapted lexical decision task. We identify age, education, and multilingualism as the most important factors influencing vocabulary size. The results suggest that the accumulation of vocabulary throughout life and in multiple languages mirrors the logarithmic growth of number of types with number of tokens observed in text corpora (Herdan's law). Moreover, the vocabulary that multilinguals acquire in related languages seems to increase their first language (L1) vocabulary size and outweighs the loss caused by decreased exposure to L1. In addition, we show that corpus word frequency and prevalence are complementary measures of word occurrence covering a broad range of language experiences. Prevalence is shown to be the strongest independent predictor of word processing times in the Dutch Lexicon Project, making it an important variable for psycholinguistic research.

  9. On-line digital holographic measurement of size and shape of microparticles for crystallization processes

    Science.gov (United States)

    Khanam, Taslima; Darakis, Emmanouil; Rajendran, Arvind; Kariwala, Vinay; Asundi, Anand K.; Naughton, Thomas J.

    2008-09-01

    Crystallization is a widely used chemical process that finds applications in pharmaceutical industries. In an industrial crystallization process, it is not only important to produce pure crystals but also to control the shape and size of the crystals, as they affect the efficiency of downstream processes and the dissolution property of the drug. The effectiveness of control algorithms depend on the availability of on-line, real-time information about these critical properties. In this paper, we investigate the use of lens-less in-line digital holographic microscopy for size and shape measurements for crystallization processes. For this purpose, we use non-crystalline spherical microparticles and carbon fibers with known sizes present in a liquid suspension as test systems. We propose an algorithm to extract size and shape information for a population of microparticles from the experimentally recorded digital holograms. The measurements obtained from the proposed method show good agreement with the corresponding known size and shape of the particles.

  10. Understanding channel purchase intentions : Measuring online and offline shopping value perceptions

    NARCIS (Netherlands)

    Broekhuizen, T.L.J.

    2006-01-01

    This dissertation investigates consumers’ prepurchase evaluations of buying books offline and online. It synthesizes the E-Commerce and perceived value literature to develop a conceptual model that explains online and offline purchase intentions. Based on this literature review, it is proposed that

  11. Understanding channel purchase intentions : Measuring online and offline shopping value perceptions

    NARCIS (Netherlands)

    Broekhuizen, T.L.J.

    2006-01-01

    This dissertation investigates consumers’ prepurchase evaluations of buying books offline and online. It synthesizes the E-Commerce and perceived value literature to develop a conceptual model that explains online and offline purchase intentions. Based on this literature review, it is proposed that

  12. A Question of Interface Design: How Do Online Service GUIs Measure Up?

    Science.gov (United States)

    Head, Alison J.

    1997-01-01

    Describes recent improvements in graphical user interfaces (GUIs) offered by online services. Highlights include design considerations, including computer engineering capabilities and users' abilities; fundamental GUI design principles; user empowerment; visual communication and interaction; and an evaluation of online search interfaces. (LRW)

  13. Accurate tissue area measurements with considerably reduced radiation dose achieved by patient-specific CT scan parameters

    DEFF Research Database (Denmark)

    Brandberg, J.; Bergelin, E.; Sjostrom, L.

    2008-01-01

    for muscle tissue. Image noise was quantified by standard deviation measurements. The area deviation was radiation dose of the low-dose technique was reduced to 2-3% for diameters of 31-35 cm and to 7.5-50% for diameters of 36-47 cm......A low-dose technique was compared with a standard diagnostic technique for measuring areas of adipose and muscle tissue and CT numbers for muscles in a body composition application. The low-dose technique was intended to keep the expected deviation in the measured area of adipose and muscle tissue...... to low-dose technique. 17 patients - chosen to cover a wide range of diameters (31-47 cm) for both abdomen and thighs - were examined using both techniques. Tissue areas were compared, as were CT numbers...

  14. Assessment of metabolic properties and kinetic parameters of methanogenic sludge by on-line methane production rate measurements

    NARCIS (Netherlands)

    Gonzalez-Gil, G.; Kleerebezem, R.; Lettinga, G.

    2002-01-01

    This report presents a new approach to studying the metabolic and kinetic properties of anaerobic sludge from single batch experiments. The two main features of the method are that the methane production is measured on-line with a relatively cheap system, and that the methane production data can be

  15. Measuring MFT's Mental Health Literacy and Competence: The Effects of an On-Line Introductory Workshop on Eating Disorders

    Science.gov (United States)

    Beck-Ellsworth, Danielle

    2011-01-01

    Purpose of study: The purpose of the validity study was to establish known-groups validity of the two measures used for the main study by comparing the responses of the Eating Disorder experts and non-experts. The purpose of the main study was to develop an on-line introductory workshop on eating disorders and investigate the levels of competency…

  16. Measuring MFT's Mental Health Literacy and Competence: The Effects of an On-Line Introductory Workshop on Eating Disorders

    Science.gov (United States)

    Beck-Ellsworth, Danielle

    2011-01-01

    Purpose of study: The purpose of the validity study was to establish known-groups validity of the two measures used for the main study by comparing the responses of the Eating Disorder experts and non-experts. The purpose of the main study was to develop an on-line introductory workshop on eating disorders and investigate the levels of competency…

  17. A system for accurate on-line measurement of total gas consumption or production rates in microbioreactors

    NARCIS (Netherlands)

    van Leeuwen, Michiel; Heijnen, Joseph J.; Gardeniers, Johannes G.E.; Oudshoorn, Arthur; Noorman, Henk; Visser, Jan; van der Wielen, Luuk A.M.; van Gulik, Walter M.

    2009-01-01

    A system has been developed, based on pressure controlled gas pumping, for accurate measurement of total gas consumption or production rates in the nmol/min range, applicable for on-line monitoring of bioconversions in microbioreactors. The system was validated by carrying out a bioconversion with

  18. A system for accurate on-line measurement of total gas consumption or production rates in microbioreactors

    NARCIS (Netherlands)

    Leeuwen, van Michiel; Heijnen, Joseph J.; Gardeniers, Han; Oudshoorn, Arthur; Noorman, Henk; Visser, Jan; Wielen, van der Luuk A.M.; Gulik, van Walter M.

    2009-01-01

    A system has been developed, based on pressure controlled gas pumping, for accurate measurement of total gas consumption or production rates in the nmol/min range, applicable for on-line monitoring of bioconversions in microbioreactors. The system was validated by carrying out a bioconversion with k

  19. Identification of imine or enamine drug metabolites using online hydrogen/deuterium exchange and exact mass measurements.

    Science.gov (United States)

    Li, Austin C; Yu, Erya; Ring, Steven C; Chovan, James P

    2012-04-30

    Drug metabolites that have imine or enamine partial structures cause extra mass-to-charge (m/z) increases in online hydrogen/deuterium exchange (HDX) in addition to hydroxyl or amine protons. Online HDX and exact mass measurement were used herein to characterize this extra increase property, and to further confirm proposed metabolite structures. Metabolites of two proprietary compounds as well as two commercially available compounds were analyzed using aqueous and HDX liquid chromatography coupled with an LTQ-Orbitrap. The exact mass measurements of both the precursor ions and product ions were acquired through data-dependent acquisition and compared with theoretical values of proposed fragment ions. Analysis of exact mass measurements of metabolite product ions under both normal aqueous and HDX conditions led to the identification of the isoxazole ring opening of compound C-1, and a double-bond formation on the methylpyrrolidine ring of compound C-2 during biotransformation. In both cases, imine or enamine structures formed in the metabolites caused extra m/z increases upon HDX that contributed confirmatory information to the structure identification. The compound 3,3-diphenyl-2-ethyl-1-pyrroline also demonstrated that the methylene protons adjacent to the imine were exchanged during online HDX. The exchangeability of methylene protons adjacent to imine or enamine moieties proved to be useful to narrow down or even pinpoint the metabolism sites of parent drugs when high-resolution exact mass measurement and online HDX were used. Copyright © 2012 John Wiley & Sons, Ltd.

  20. Optimizing the locations of the measuring points for an online calculation of the exhaust flue-gas loss

    Energy Technology Data Exchange (ETDEWEB)

    Drobnic, B.; Oman, J.; Kustrin, I.; Rotnik, U. [Faculty of Mechanical Engineering, Ljubljana (Slovenia); Uros Rotnik Sostanj Power Plant, Sostanj (Slovenia)

    2005-03-01

    Flue gas properties are very important for evaluation of a boiler's performance. Non-homogeneity of the properties and large dimensions of flue-gas ducts require measurements with large number of measuring points to provide high accuracy of measurement results. An analysis of simpler measuring methods is presented. It is shown that high accuracy can be achieved with small number of measuring points if their positions are optimised with respect to pre-determined conditions in the flue gas duct. The methods can be used as operational measurements to monitor boiler's performance and for on-line calculation of boiler's efficiency. (orig.)

  1. A within-subjects trial to test the equivalence of online and paper outcome measures: the Roland Morris Disability Questionnaire

    Directory of Open Access Journals (Sweden)

    Prentice Philippa

    2010-06-01

    Full Text Available Abstract Background Augmenting validated paper versions of existing outcome measures with an equivalent online version may offer substantial research advantages (cost, rapidity and reliability. However, equivalence of online and paper questionnaires cannot be assumed, nor can acceptability to respondents. The aim was to test whether online and written versions of the Roland Morris Disability Questionnaire (RMDQ, a standard measure of functional disability in back pain, are equivalent at both group and individual levels to establish whether they can be used interchangeably. Methods This is a within-participants equivalence study. 167 participants with back pain fully completed both the paper and online versions of the RMDQ in random order. Participants were recruited from a chiropractic clinic and patient support groups in Southern England. Limits of equivalence were pre-defined as 0.5 RMDQ points, the Bland-Altman range was calculated, and participants' comments were examined using content analysis. Results The mean score difference was 0.03 (SD = 1.43, with the 95% Confidence Interval falling entirely within our limits of equivalence (-0.19 to 0.25. The Bland-Altman range was -2.77 to 2.83 RMDQ points. Participants identified unique advantages and disadvantages associated with each version of the RMDQ. Conclusions The group and individual level data suggest that online and paper versions of the RMDQ are equivalent and can be used interchangeably. The Bland-Altman range appears to reflect the known measurement properties of the RMDQ. Furthermore, participants' comments confirmed the potential value to be had from offering them the choice of completing the RMDQ online or on paper.

  2. Measurement uncertainty analysis of low-dose-rate prostate seed brachytherapy: post-implant dosimetry.

    Science.gov (United States)

    Gregory, Kent J; Pattison, John E; Bibbo, Giovanni

    2015-03-01

    The minimal dose covering 90 % of the prostate volume--D 90--is arguably the most important dosimetric parameter in low-dose-rate prostate seed brachytherapy. In this study an analysis of the measurement uncertainties in D 90 from low-dose-rate prostate seed brachytherapy was conducted for two common treatment procedures with two different post-implant dosimetry methods. The analysis was undertaken in order to determine the magnitude of D 90 uncertainty, how the magnitude of the uncertainty varied when D 90 was calculated using different dosimetry methods, and which factors were the major contributors to the uncertainty. The analysis considered the prostate as being homogeneous and tissue equivalent and made use of published data, as well as original data collected specifically for this analysis, and was performed according to the Guide to the expression of uncertainty in measurement (GUM). It was found that when prostate imaging and seed implantation were conducted in two separate sessions using only CT images for post-implant analysis, the expanded uncertainty in D 90 values were about 25 % at the 95 % confidence interval. When prostate imaging and seed implantation were conducted during a single session using CT and ultrasound images for post-implant analysis, the expanded uncertainty in D 90 values were about 33 %. Methods for reducing these uncertainty levels are discussed. It was found that variations in contouring the target tissue made the largest contribution to D 90 uncertainty, while the uncertainty in seed source strength made only a small contribution. It is important that clinicians appreciate the overall magnitude of D 90 uncertainty and understand the factors that affect it so that clinical decisions are soundly based, and resources are appropriately allocated.

  3. Measurement of the internal dose to families of outpatients treated with {sup 131}I for hyperthyroidism

    Energy Technology Data Exchange (ETDEWEB)

    Barrington, S.F.; O' Doherty, M.J. [St. Thomas' Hospital, PET Imaging Centre, London (United Kingdom); Anderson, P. [Queen Elizabeth Hospital, Department of Nuclear Medicine, Birmingham (United Kingdom); Kettle, A.G. [Kent and Canterbury Hospital, East Kent Hospitals NHS Trust, Department of Nuclear Medicine, Canterbury (United Kingdom); Gadd, R.; Mountford, P.J. [University Hospital of North Staffordshire, Directorate of Medical Physics and Clinical Technology, Stoke-on-Trent (United Kingdom); Thomson, W.H.; Harding, L.K. [City Hospital, Department of Physics and Nuclear Medicine, Birmingham (United Kingdom); Batchelor, S. [Guy' s and St Thomas' Hospital, Department of Medical Physics, London (United Kingdom)

    2008-11-15

    The aim of this study was to measure the internal dose received by family members from ingestion of radioactive contamination after outpatient therapy. Advice was given to minimise transfer of radioiodine. Home visits were made approximately 2, 7 and 21 days after treatment to measure radioactivity in the thyroids of family members. A decay correction was applied to radioactivity detected assuming ingestion had occurred at the earlier contact time, either the day of treatment or the previous home visit. An effective half-life of 6 or 7 days was used depending on age. Thyroid activity was summed if activity was found at more than one visit in excess of the amount attributable to radioactive decay. Effective dose (ED) was calculated using ICRP72. Fifty-three adults and 92 children, median age 12 (range 4-17) years participated. Median administered activity was 576 (range 329-690) MBq {sup 131}I. Thyroid activity ranged from 0 to 5.4 kBq in the adults with activity detected in 17. Maximum adult ED was 0.4 mSv. Thyroid activity ranged from 0 to 11.8 kBq in the children with activity detected in 26. The two highest values of 5.0 and 11.8 kBq occurred in children aged 5 and 14 years from different families. Eighty-five children had no activity or <1 kBq detected. ED was <0.2 mSv in 86 out of 92 children (93%). Previous published data showed 93% of children received an ED {<=}0.8 mSv from external irradiation. With advice, families of outpatients receiving radioiodine should be able to comply with statutory dose limits and constraints. (orig.)

  4. Measurement of the Radiation Dose Rates of Patients Receiving Treatment with I-131 Using Telescopic Radiation Survey Meter

    Directory of Open Access Journals (Sweden)

    Yehia Lahfi

    2016-03-01

    Full Text Available Introduction In order to discharge the patients receiving treatment with large radiation doses of 131I for thyroid cancer, it is necessary to measure and evaluate the external dose rates of these patients. The aim of the study was to assess a new method of external dose rate measurement, and to analyze the obtained results as a function of time. Materials and Methods In this study, a telescopic radiation survey meter was utilized to measure the external dose rates of a sample population of 192 patients receiving treatment with high-dose 131I at one, 24, and 48 hours after dose administration. Results The proposed technique could reduce the occupational radiation exposure of the physicist by a factor of 1/16. Moreover, the external dose rates of both genders rapidly decreased with time according to bi-exponential equations, which could be attributed to the additional factors associated with iodine excretion, as well as the physiology of the body in terms of 131I uptake. Conclusion According to the results of this study, telescopic radiation survey meter could be used to measure the external dose rates of patients receiving treatment with 131I. Furthermore, the average difference in the radiation exposure between female and male patients was calculated to be less than 17%.

  5. Reconstruction of high-resolution 3D dose from matrix measurements : error detection capability of the COMPASS correction kernel method

    NARCIS (Netherlands)

    Godart, J.; Korevaar, E. W.; Visser, R.; Wauben, D. J. L.; van t Veld, Aart

    2011-01-01

    TheCOMPASS system (IBADosimetry) is a quality assurance (QA) tool which reconstructs 3D doses inside a phantom or a patient CT. The dose is predicted according to the RT plan with a correction derived from 2D measurements of a matrix detector. This correction method is necessary since a direct recon

  6. Effects of measurement strategy and statistical analysis on dose-response relations between physical workload and low back pain

    NARCIS (Netherlands)

    J.J.P. Jansen (Justin); A. Burdorf (Alex)

    2003-01-01

    textabstractBACKGROUND: In epidemiological studies on physical workloads and back complaints, among the important features in modelling dose-response relations are the measurement strategy of the exposure and the nature of the dose-response relation that is assumed. AIM: To evaluat

  7. Accelerometer-measured dose-response for physical activity, sedentary time, and mortality in US adults

    DEFF Research Database (Denmark)

    Matthews, Charles E; Keadle, S. K.; Troiano, Richard P

    2016-01-01

    Background: Moderate-to-vigorous-intensity physical activity is recommended to maintain and improve health, but the mortality benefits of light activity and risk for sedentary time remain uncertain. Objectives: Using accelerometer-based measures, we 1) described the mortality dose-response for se......Background: Moderate-to-vigorous-intensity physical activity is recommended to maintain and improve health, but the mortality benefits of light activity and risk for sedentary time remain uncertain. Objectives: Using accelerometer-based measures, we 1) described the mortality dose......-response for sedentary time and light-and moderateto-vigorous-intensity activity using restricted cubic splines, and 2) estimated the mortality benefits associated with replacing sedentary time with physical activity, accounting for total activity. Design: US adults (n = 4840) from NHANES (2003-2006) wore...... an accelerometer for #7 d and were followed prospectively for mortality. Proportional hazards models were used to estimate adjusted HRs and 95% CIs for mortality associations with time spent sedentary and in light-and moderate-to-vigorous-intensity physical activity. Splines were used to graphically present...

  8. Automatic system for measuring dose-area product (DAP) in ROI fluoroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kezerashvili, M.; Bednarek, D.R.; Rudin, S. [Departments of Radiology and Biophysical Sciences, University at Buffalo, State University of New York, Buffalo, NY (United States)

    1997-04-01

    A computerized system for monitoring dose-area product (DAP) has been developed for region of interest (ROI) fluoroscopy in which patient exposure is reduced using an x-ray attenuating filter with an aperture. The system includes an IBM compatible computer which is connected through an IEEE-488 interface to an electrometer which measures the charge from a DAP ionization chamber. A digital input/output board connects the computer to the filter placement device to determine whether the filter is in or out of the beam, and to the x-ray generator to determine when the exposure is due to spot filming. The computer logs the DAP from conventional fluoroscopy, ROI fluoroscopy and spot filming separately, applying the appropriate calibration factor for each. Measured DAPs, fluoroscopic DAP rates and exposure times are displayed in real-time. The system has been installed in a GI fluoroscopic room so that the dose-reduction potential of ROI imaging can be evaluated. (author)

  9. Dose profile monitoring with carbon ions by means of prompt-gamma measurements

    Energy Technology Data Exchange (ETDEWEB)

    Testa, E. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France)], E-mail: e.testa@ipnl.in2p3.fr; Bajard, M.; Chevallier, M.; Dauvergne, D.; Le Foulher, F. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France); Freud, N.; Letang, J.M. [Institut National des Sciences Appliquees de Lyon, Laboratoire de Controle Non-Destructif par Rayonnements Ionisants (France); Poizat, J.C.; Ray, C.; Testa, M. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, F-69003 Lyon, Universite Lyon 1 and IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne (France)

    2009-03-15

    A key point in the quality control of ion therapy is real-time monitoring and imaging of the dose delivered to the patient. Among the possible signals that can be used to make such a monitoring, prompt gamma-rays issued from nuclear fragmentation are possible candidates, provided the correlation between the emission profile and the primary beam range can be established. By means of simultaneous energy and time-of-flight discrimination, we could measure the longitudinal profile of the prompt gamma-rays emitted by 73 MeV/u carbon ions stopping inside a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered gamma rays, and to find a good correlation between the prompt-gamma profile and the ion range. This profile was studied as a function of the observation angle. By extrapolating our results to higher energies and realistic detection efficiencies, we showed that prompt gamma-ray measurements make it feasible to control in real time the longitudinal dose during ion therapy treatments.

  10. Measurement and properties of the dose-area product ratio in external small-beam radiotherapy

    Science.gov (United States)

    Niemelä, Jarkko; Partanen, Mari; Ojala, Jarkko; Sipilä, Petri; Björkqvist, Mikko; Kapanen, Mika; Keyriläinen, Jani

    2017-06-01

    In small-beam radiation therapy (RT) the measurement of the beam quality parameter, i.e. the tissue-phantom ratio or TPR20,10, using a conventional point detector is a challenge. To obtain reliable results, one has to consider potential sources of error, including volume averaging and adjustment of the point detector into the narrow beam. To overcome these challenges, a different type of beam quality parameter in small beams was studied, namely the dose-area product ratio, or DAPR20,10. With this method, the measurement of a dose-area product (DAP) using a large-area plane-parallel chamber (LAC) eliminates the uncertainties in detector positioning and volume averaging that are present when using a point detector. In this study, the properties of the DAPR20,10 of a cone-collimated 6 MV photon beam were investigated using Monte Carlo (MC) calculations and the obtained values were compared to measurements obtained using two LAC detectors, PTW Type 34073 and PTW Type 34070. In addition, the possibility of determining the DAP using EBT3 film and a Razor diode detector was studied. The determination of the DAPR20,10 value was found to be feasible in external small-beam radiotherapy using cone-collimated beams with diameters from 4-40 mm, based on the results of the two LACs, the MC calculations and the Razor diode. The measurements indicated a constant DAPR20,10 value for fields 20-40 mm in diameter, with a maximum relative change of 0.6%, but an increase of 7.0% for fields from 20-4 mm in diameter for the PTW Type 34070 chamber. Simulations and measurements showed an increase of DAPR20,10 with increasing LAC size or dose integral area for the studied 4-40 mm cone-collimated 6 MV photon beams. This has the consequence that there should be a reference to the size of the used LAC active area or the DAP integration area with the reported DAPR20,10 value.

  11. Measurement and properties of dose-area product ratio in external small-beam radiotherapy.

    Science.gov (United States)

    Niemelä, Jarkko Tapio; Partanen, Mari; Ojala, Jarkko; Sipilae, Petri; Björkqvist, Mikko; Kapanen, Mika; Keyriläinen, Jani

    2017-03-22

    In small-beam radiation therapy (RT) the measurement of beam quality parameter i.e. tissue-phantom ratio or TPR20,10 with conventional point detector is a challenge. To obtain reliable results, one has to consider potential sources of error, including volume averaging and adjustment of the point detector into the narrow beam. To overcome these challenges, a different type of possible beam quality parameter in small beams was studied, namely the dose-area product ratio or DAPR20,10. With this method, the measurement of a dose-area product (DAP) with a large-area plane-parallel chamber (LAC) eliminates the uncertainties in detector positioning and volume averaging present with the use of a point detector. In this study, properties of DAPR20,10 of cone-collimated 6 MV photon beam were investigated with Monte Carlo (MC) calculations and the obtained values were compared to measurements obtained by two LAC detectors PTW Type 34073 and PTW Type 34070. In addition, the possibility of determining the DAP with EBT3 film and Razor diode detector was studied. The determination of DAPR20,10 value was found to be feasible in external small-beam radiotherapy of cone-collimated beams with diameters from 4 to 40 mm with the two LACs, MC calculation and Razor diode. Measurements indicated a constant DAPR20,10 value for fields from 20 to 40 mm in diameter with maximum relative change of 0.6%, but an increase of 7.0% for fields from 20 to 4 mm in diameter for PTW Type 34070 chamber. Simulations and measurements showed an increase of DAPR20,10 with increasing LAC size or dose integral area for studied cone-collimated 6 MV photon beams from 4 to 40 mm in diameter. This has a consequence that with reported DAPR20,10 value there should be a reference to the size of the used LAC active area or the DAP integration area.

  12. Back-traceable measurement of very small doses; Rueckfuehrbare Messung sehr kleiner Dosen

    Energy Technology Data Exchange (ETDEWEB)

    Balg, Sabrina [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Fachbereich 6.3 ' Strahlenschutzdosimetrie'

    2012-07-01

    A 1-litre ionization chamber (HSO1-chamber) to measure the ambient dose equivalent by means of additional coating was optimized by Ankerhold, especially for low-energy photon beams below 40 keV. This should be done also for the similar 10-litre ionization chamber (HS10-chamber). A casing of the HS10-ionization chamber with 4.5 mm thick Ultraform half-shells was shown to be optimal for this purpose. The core of this paper is the choice of material and the determination of the thickness of the half-shell production by measuring the response of the ionization chamber at different photon energies. Furthermore, the influence of the series dispersion of HS10-chambers on the optimization is checked. The results are then compared with those of the optimized HS01-chamber. (orig.)

  13. SU-F-BRF-13: Investigating the Feasibility of Accurate Dose Measurement in a Deforming Radiochromic Dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Juang, T [Medical Physics Graduate Program, Duke University Medical Center, Durham, NC (United States); Adamovics, J [Rider University, Skillman, NJ (United States); Oldham, M [Duke University Medical Center, Durham, NC (United States)

    2014-06-15

    Purpose: Presage-Def, a deformable radiochromic 3D dosimeter, has been previously shown to have potential for validating deformable image registration algorithms. This work extends this effort to investigate the feasibility of using Presage-Def to validate dose-accumulation algorithms in deforming structures. Methods: Two cylindrical Presage-Def dosimeters (8cm diameter, 4.5cm length) were irradiated in a water-bath with a simple 4-field box treatment. Isocentric dose was 20Gy. One dosimeter served as control (no deformation) while the other was laterally compressed during irradiation by 21%. Both dosimeters were imaged before and after irradiation with a fast (∼10 minutes for 1mm isotropic resolution), broad beam, high resolution optical-CT scanner. Measured dose distributions were compared to corresponding distributions calculated by a commissioned Eclipse planning system. Accuracy in the control was evaluated with 3D gamma (3%/3mm). The dose distribution calculated for the compressed dosimeter in the irradiation geometry cannot be directly compared via profiles or 3D gamma to the measured distribution, which deforms with release from compression. Thus, accuracy under deformation was determined by comparing integral dose within the high dose region of the deformed dosimeter distribution versus calculated dose. Dose profiles were used to study temporal stability of measured dose distributions. Results: Good dose agreement was demonstrated in the control with a 3D gamma passing rate of 96.6%. For the dosimeter irradiated under compression, the measured integral dose in the high dose region (518.0Gy*cm3) was within 6% of the Eclipse-calculated integral dose (549.4Gy*cm3). Elevated signal was noted on the dosimeter edge in the direction of compression. Change in dosimeter signal over 1.5 hours was ≤2.7%, and the relative dose distribution remained stable over this period of time. Conclusion: Presage-Def is promising as a 3D dosimeter capable of accurately

  14. Results of dose sensors measurements in the middle-Earth orbit for the period of 2009-2015

    Science.gov (United States)

    Protopopov, Grigory; Shatov, Pavel; Tasenko, Sergey; Lyakhov, Igor; Makarova, Nina; Balashov, Sergey; Sitnikova, Ninel

    2016-07-01

    The measurements results of space radiation exposure on electronic components carried out by dose sensors are presented in the paper. Dose sensors operate on metal-nitride-oxide-semiconductor dosimetry pricniple. The flight data have been receiving for more than 6 years. The measurements results are compared with others flight data on different orbits. The analysis of the received data from 2009 to 2015 allows us to find out the periods with sharp increase of dose rate and to define values of such increases. We had analyzed space radiation characteristics data from other monitoring systems (such as GOES, Electro-L) in dates of dose rate sharp increase. Results of the analysis of dose rate increase, which had been fixed by TID sensors in 2015, will be presented in full paper. We had calculated average dose rates for different space models in the middle-Earth orbit (AE8, AE9 and others) and determined the most relevant models to the experimental data (with account for relaxation effect of dose sensor outputs). The comparison results for different models will be presented in the full paper. We had used different approaches for simulating of dose sensors shielding geometry, such as semi-sphere, semi-infinite plate, sector analysis, with taking account of different shielding elements. The analysis results of shielding configuration influence on calculated values of dose rate will be presented in the full paper.

  15. Dose Measurements of Parotid Glands and Spinal Cord in Conventional Treatment of Nasopharyngeal Carcinoma Using RANDO Phantom and Thermoluminescent Dosimeters

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Bahreyni Toossi

    2015-07-01

    Full Text Available Introduction Radiotherapy is regarded as the first treatment of choice for nasopharyngeal carcinoma. Despite the advantages of radiotherapy, patients may suffer from a wide range of side-effects due to the presence of many sensitive normal tissues in these regions. If the absorbed dose exceeds the tolerance level in parotid glands and the spinal cord, myelopathy, Lhermitte's sign and xerostomia cannot be avoided. Materials and Methods The head and neck of a RANDO phantom (reference man, which was regarded as a hypothetical patient with nasopharyngeal carcinoma was evaluated. The full course of treatment consisted of three phases. At the beginning of each phase, an oncologist marked conventional fields on the RANDO phantom using a simulator. For measuring the absorbed dose, Thermoluminescent Dosimeters(TLD chips (TLD-100 were utilized.The absorbed dose by TLDs was read by Harshaw 3500 TLD reader. Results The total absorbed dose was calculated by measuring the absorbed dose in each phase, multiplied by the fraction numbers of each phase; the obtained values were summed up. The results showed that the received doses by spinal cord ranged from 15.24 to 54.56 Gy. Also, the absorbed dose of parotid glands was approximately 39.23 Gy. Conclusion Considering the minimum tolerance dose the absorbed doses in the spinal cord and parotid glands were above the tolerance level. The incidence rate of xerostomia and myelopathy were higher in patients, treated by conventional methods.

  16. WE-G-218-02: The Measurement of Absorbed Dose to Active Intravenous Cardiac Devices in Patients Undergoing Radiotherapy.

    Science.gov (United States)

    Reft, C

    2012-06-01

    Radiotherapy departments are seeing an increasing number of patients presenting for treatment with active intravenous cardiac devices (AICDs). This is due to an increasing aging population and technology advances in these devices. The AAPM TG-34 addressed the radiation effects in these devices and provided recommendations for patients with these devices undergoing radiotherapy. The current devices utilizing CMOS technology are more sensitive to radiation then the older bipolar devices. Therefore, it is important to estimate the dose to the device to ensure that the radiation does not adversely affect the performance of the device. This is particularly important for patients dependent on their accurate functioning. The dose to the device is generally from secondary radiation and is typically below 0.05 Gy with most of it coming from lower energy scatter radiation. Treatment planning systems can be used to estimate the dose to the device. However, these systems do not accurately calculate doses at distances more than 2-3 cm from the field edge. For these out-of-field dose measurements the dosimeter requires a high sensitivity and a relatively flat energy response. Thermoluminescent detectors and optically stimulated luminescent detectors satisfy these requirements and they are relatively unobtrusive. The newer formulations of radiochromic film with higher sensitivity can also be used. The detector should be place under 0.5 to 1.0 cm of bolus to minimize the contaminating head-scatter electrons provide a more realistic measurement of the dose to the device. 1. List the reasons for estimating the dose to the AICDs 2. Provide a discussion on the various methods which include calculations and measurements to estimate the dose to the device as well as the uncertainties in these estimates. 3. Identify detectors that satisfy the requirements for these in-vivo out-of-field dose measurements as well as describe the appropriate correction factors to apply for accurate dose

  17. Influence of radiation dose and iterative reconstruction algorithms for measurement accuracy and reproducibility of pulmonary nodule volumetry: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungjin, E-mail: khj.snuh@gmail.com [Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of); Park, Chang Min, E-mail: cmpark@radiol.snu.ac.kr [Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of); Cancer Research Institute, Seoul National University, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of); Song, Yong Sub, E-mail: terasong@gmail.com [Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of); Lee, Sang Min, E-mail: sangmin.lee.md@gmail.com [Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of); Goo, Jin Mo, E-mail: jmgoo@plaza.snu.ac.kr [Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of); Cancer Research Institute, Seoul National University, 101, Daehangno, Jongno-gu, Seoul 110-744 (Korea, Republic of)

    2014-05-15

    Purpose: To evaluate the influence of radiation dose settings and reconstruction algorithms on the measurement accuracy and reproducibility of semi-automated pulmonary nodule volumetry. Materials and methods: CT scans were performed on a chest phantom containing various nodules (10 and 12 mm; +100, −630 and −800 HU) at 120 kVp with tube current–time settings of 10, 20, 50, and 100 mAs. Each CT was reconstructed using filtered back projection (FBP), iDose{sup 4} and iterative model reconstruction (IMR). Semi-automated volumetry was performed by two radiologists using commercial volumetry software for nodules at each CT dataset. Noise, contrast-to-noise ratio and signal-to-noise ratio of CT images were also obtained. The absolute percentage measurement errors and differences were then calculated for volume and mass. The influence of radiation dose and reconstruction algorithm on measurement accuracy, reproducibility and objective image quality metrics was analyzed using generalized estimating equations. Results: Measurement accuracy and reproducibility of nodule volume and mass were not significantly associated with CT radiation dose settings or reconstruction algorithms (p > 0.05). Objective image quality metrics of CT images were superior in IMR than in FBP or iDose{sup 4} at all radiation dose settings (p < 0.05). Conclusion: Semi-automated nodule volumetry can be applied to low- or ultralow-dose chest CT with usage of a novel iterative reconstruction algorithm without losing measurement accuracy and reproducibility.

  18. Computed tomography dose measurements with radiochromic films and a flatbed scanner.

    Science.gov (United States)

    Rampado, O; Garelli, E; Ropolo, R

    2010-01-01

    Gafchromic XR-QA films were developed for patient dosimetry in diagnostic radiology. A possible application of these films is the measurement of doses in computed tomography. In this study a method to evaluate the CTDI using Gafchromic XR-QA film and a flatbed scanner was developed and tested. Film samples were cut to dimensions of 6 x 170 mm2 in order to have an integration area similar to that of a pencil ionization chamber, with the possibility of changing the integration length. Prior to exposing these films to a computed tomography beam, the angular dependence of the film dose response was investigated by exposing film strips to a static x-ray beam at different angles in the range 0 degrees-180 degrees. A difference of 49% was found between the response with the axis beam parallel to the film surface (90 degrees) and with the axis beam perpendicular (0 degrees and 180 degrees). Integrating over a 360 degrees exposure like the one in computed tomography, a difference of less than 2% was estimated, which is comparable with the measurement error obtainable with XR-QA film. A calibration with a CT beam in the scout mode was performed and film strips were then exposed to single axial scans and to helical scans both in air and in phantoms. Two different types of flatbed scanners were used to read the film samples, a Microtek ScanMaker 9800XL scanner and an Epson Expression 10000 XL scanner, and the accuracy of the results were compared. For beam collimations above 10 mm differences between CTDI measured by film and CTDI measured by ionization chamber below 9% were found for the Epson scanner, with an average estimated error at 1 sigma level of 5%. For the Microtek scanner and for the same film samples, differences below 11% with an average error at 1 sigma level of 8% were founded. The 1 sigma uncertainty of the measured CTDI was provided by the method for each measurement, and it was shown that about the 95% of the differences between the CTDI measurements with

  19. Cosmic radiation dose measurements from the RaD-X flight campaign

    Science.gov (United States)

    Mertens, Christopher J.; Gronoff, Guillaume P.; Norman, Ryan B.; Hayes, Bryan M.; Lusby, Terry C.; Straume, Tore; Tobiska, W. Kent; Hands, Alex; Ryden, Keith; Benton, Eric; Wiley, Scott; Gersey, Brad; Wilkins, Richard; Xu, Xiaojing

    2016-10-01

    The NASA Radiation Dosimetry Experiment (RaD-X) stratospheric balloon flight mission obtained measurements for improving the understanding of cosmic radiation transport in the atmosphere and human exposure to this ionizing radiation field in the aircraft environment. The value of dosimetric measurements from the balloon platform is that they can be used to characterize cosmic ray primaries, the ultimate source of aviation radiation exposure. In addition, radiation detectors were flown to assess their potential application to long-term, continuous monitoring of the aircraft radiation environment. The RaD-X balloon was successfully launched from Fort Sumner, New Mexico (34.5°N, 104.2°W) on 25 September 2015. Over 18 h of flight data were obtained from each of the four different science instruments at altitudes above 20 km. The RaD-X balloon flight was supplemented by contemporaneous aircraft measurements. Flight-averaged dosimetric quantities are reported at seven altitudes to provide benchmark measurements for improving aviation radiation models. The altitude range of the flight data extends from commercial aircraft altitudes to above the Pfotzer maximum where the dosimetric quantities are influenced by cosmic ray primaries. The RaD-X balloon flight observed an absence of the Pfotzer maximum in the measurements of dose equivalent rate.

  20. Issues in the reconstruction of environmental doses on the basis of thermoluminescence measurements in the Techa riverside

    Science.gov (United States)

    Bougrov, N. G.; Goksu, H. Y.; Haskell, E.; Degteva, M. O.; Meckbach, R.; Jacob, P.; Neta, P. I. (Principal Investigator)

    1998-01-01

    The potential of thermoluminescence measurements of bricks from the contaminated area of the Techa river valley, Southern Urals, Russia, for reconstructing external exposures of affected population groups has been studied. Thermoluminescence dating of background samples was used to evaluate the age of old buildings available on the river banks. The anthropogenic gamma dose accrued in exposed samples is determined by subtracting the natural radiation background dose for the corresponding age from the accumulated dose measured by thermoluminescence. For a site in the upper Techa river region, where the levels of external exposures were extremely high, the depth-dose distribution in bricks and the dependence of accidental dose on the height of the sampling position were determined. For the same site, Monte Carlo simulations of radiation transport were performed for different source configurations corresponding to the situation before and after the construction of a reservoir on the river and evacuation of the population in 1956. A comparison of the results provides an understanding of the features of the measured depth-dose distributions and height dependencies in terms of the source configurations and shows that bricks from the higher sampling positions are likely to have accrued a larger fraction of anthropogenic dose from the time before the construction of the reservoir. The applicability of the thermoluminescent dosimetry method to environmental dose reconstruction in the middle Techa region, where the external exposure was relatively low, was also investigated.

  1. Issues in the reconstruction of environmental doses on the basis of thermoluminescence measurements in the Techa riverside

    Science.gov (United States)

    Bougrov, N. G.; Goksu, H. Y.; Haskell, E.; Degteva, M. O.; Meckbach, R.; Jacob, P.; Neta, P. I. (Principal Investigator)

    1998-01-01

    The potential of thermoluminescence measurements of bricks from the contaminated area of the Techa river valley, Southern Urals, Russia, for reconstructing external exposures of affected population groups has been studied. Thermoluminescence dating of background samples was used to evaluate the age of old buildings available on the river banks. The anthropogenic gamma dose accrued in exposed samples is determined by subtracting the natural radiation background dose for the corresponding age from the accumulated dose measured by thermoluminescence. For a site in the upper Techa river region, where the levels of external exposures were extremely high, the depth-dose distribution in bricks and the dependence of accidental dose on the height of the sampling position were determined. For the same site, Monte Carlo simulations of radiation transport were performed for different source configurations corresponding to the situation before and after the construction of a reservoir on the river and evacuation of the population in 1956. A comparison of the results provides an understanding of the features of the measured depth-dose distributions and height dependencies in terms of the source configurations and shows that bricks from the higher sampling positions are likely to have accrued a larger fraction of anthropogenic dose from the time before the construction of the reservoir. The applicability of the thermoluminescent dosimetry method to environmental dose reconstruction in the middle Techa region, where the external exposure was relatively low, was also investigated.

  2. Online measurements of surface tensions and viscosities based on the hydrodynamics of Taylor flow in a microchannel

    Science.gov (United States)

    Sun, Yanhong; Guo, Chaohong; Jiang, Yuyan; Wang, Tao; Zhang, Lei

    2016-11-01

    This paper demonstrates an online measurement technique which can measure both surface tension and viscosity for confined fluids in microfluidic systems. The surface tension and viscosity are determined by monitoring the liquid film thickness deposited in a microchannel based on the hydrodynamics of Taylor flow. Measurements were carried out for pure liquids and binary aqueous liquid mixtures. The results agreed well with reference data and theoretical models. This novel method has considerable potential for measuring dynamic interfacial tension of complex mixtures. Furthermore, it offers opportunity for integrating property measurement with two-phase flow in microchannel, opening new lines of applications.

  3. Turbidimetric Measurement for On-line Monitoring of SiO{sub 2} Particles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Sook; Lim, H. B. [Dankook University, Seoul (Korea, Republic of); Kim, Yang Sun [Proteonik, Inc., Ansan (Korea, Republic of)

    2004-06-15

    In this work, the fundamental study of on-line monitoring of SiO{sub 2} particles in the size range of 40 nm to 725 nm was carried out using turbidimetry. The size of particle was measured using a field emission scanning electron microscope (FE-SEM). The factors affecting on the turbidity were discussed, for example, wavelength, size, and concentration. In order to observe the dependence of turbidity on the wavelength, a turbidimetric system equipped with charged coupled detector (CCD) was built. The shape of the transmitted peak was changed and the peak maximum was shifted to the red when the concentration of particle was increased. This result indicates that the turbidity is related to the wavelength, which corresponds to the characteristic of the Mie extinction coefficient, Q, that is a function of not only particle diameter and refractive index but also wavelength. It is clear that a linear calibration curve for each particle in different size can be obtained at an optimized wavelength.

  4. Measuring Validity And Reliability of Perception of Online Collaborative Learning Questionnaire Using Rasch Model

    Directory of Open Access Journals (Sweden)

    Sharifah Nadiyah Razali

    2016-12-01

    Full Text Available This study aims to generate empirical evidence on the validity and reliability of Perception of Online Collaborative Learning Questionnaire (POCLQ using Rasch model. The questionnaire was distributed to 32 (N=32 Diploma Hotel Catering students from Politeknik Ibrahim Sultan, Johor (PIS. Data obtained was analysed using WINSTEP version 3.68 software. The finding showed that POCLQ had high reliability with five categories of difficulties items. So, it can be concluded that POCLQ is reliable and strongly accepted. Meanwhile, analysis of items fit showed there were six items that are not in the specified range and based on standardised residual correlation measurement value; there were five items found to be overlapped that should be dropped. All the items that needed to be dropped based on the analysis of result had been refined and retained for the purpose of the study and based on expert's view. Therefore, all items remained after Rasch analysis. It is hoped that this study will give emphasis to other researchers about the importance of analysing items to ensure the quality of an instrument being developed.

  5. Optofluidic multi-measurement system for the online monitoring of lubricant oil

    Science.gov (United States)

    Verschooten, Tom; Callewaert, Manly; Ciaccheri, Leonardo; Vervaeke, Michael; Van Erps, Jürgen; De Malsche, Wim; Grazia Mignani, Anna; Thienpont, Hugo; Ottevaere, Heidi

    2016-01-01

    We show a detection system that simultaneously allows absorbance (ABS), laser-induced fluorescence (LIF) and scattering detection excited by two different laser sources at 405 nm and 450 nm. The heart of the system consists of a mass manufacturable polymer optofluidic chip. The chip is mounted in an optical detection assembly that aligns the chip to the rest of the system, seals the chip from leakage, fixes the position and connects the channels to the rest of the fluidic system. The fluidics exhibit a reduced susceptibility to perturbations caused by air bubbles, this is accomplished by making use of a serpentine channel layout. For coumarin 480, detection limits of 100 nM and 10 pM are observed for ABS and LIF respectively. An effective detection range of 4000 down to 1 nephelometric turbidity units is shown for the detection of scattered light. The viscous behaviour of the sample is analysed by a secondary FFT processing step of which the result is further processed by multivariate data analysis. This allows the identification of samples and prediction of their quality parameters. We apply this system for the monitoring of lubricant oil, demonstrating its ability to compete with spectroscopic detection techniques. The low-cost approach and multi-measurement architecture shown in this paper pave the way for miniaturized on-line monitoring of liquids in an industrial environment.

  6. Online Measurement Perspectives for Students’ Strategy Use: Tool Use within a Content Management System

    Directory of Open Access Journals (Sweden)

    Griet Lust

    2012-01-01

    Full Text Available The current study investigates whether students’ tool use in a Content Management Systems (CMSs for example, blackboard, WebCT, relates to students’ strategy use within a CMS-supported course. In this way, the study strives to explain the tool use differences, and furthermore, it strives to find (online behavioral indications for students’ strategy use. Data were collected within a first-year undergraduate course “Learning & Instruction”. Students (n=182 reported their strategy use as measured through the Inventory of Learning Styles (Vermunt, 1998. Students’ tool use within the CMS was logged. K-means cluster analyses revealed four clusters that were characterized by different strategies and accompanying tool use. Specifically, two clusters revealed a tool use pattern that was in line with the behavioral profile of students’-reported strategy use. Interestingly, two clusters revealed a tool use pattern that was in contrast to the reported strategy use. These results raise questions with respect to students’ tool perceptions and students’ calibration capacities.

  7. Online educative activities for solar ultraviolet radiation based on measurements of cloud amount and solar exposures.

    Science.gov (United States)

    Parisi, A V; Downs, N; Turner, J; Amar, A

    2016-09-01

    A set of online activities for children and the community that are based on an integrated real-time solar UV and cloud measurement system are described. These activities use the functionality of the internet to provide an educative tool for school children and the public on the influence of cloud and the angle of the sun above the horizon on the global erythemal UV or sunburning UV, the diffuse erythemal UV, the global UVA (320-400nm) and the vitamin D effective UV. Additionally, the units of UV exposure and UV irradiance are investigated, along with the meaning and calculation of the UV index (UVI). This research will help ensure that children and the general public are better informed about sun safety by improving their personal understanding of the daily and the atmospheric factors that influence solar UV radiation and the solar UV exposures of the various wavebands in the natural environment. The activities may correct common misconceptions of children and the public about UV irradiances and exposure, utilising the widespread reach of the internet to increase the public's awareness of the factors influencing UV irradiances and exposures in order to provide clear information for minimizing UV exposure, while maintaining healthy, outdoor lifestyles.

  8. Processing of situational information in story problem texts. An analysis from on-line measures.

    Science.gov (United States)

    Orrantia, Josetxu; Muñez, David; Vicente, Santiago; Verschaffel, Lieven; Rosales, Javier

    2014-01-01

    In three experiments, we investigated the extent to which readers process information related to the construction of a situation model when they are confronted with solving word problems. Considering that generation of inferences to match actions with particular goals is part of constructing of the situation model, we constructed "rich story problems", that is, word problems included in the context of a story, in which the characters propose goals, and then these goals are followed by actions to achieve it. In Experiments 1 and 2 the story problems were designed so that the character's goal was related to the activation of a problem schema, either explicitly (Experiment 1) or implicitly (Experiment 2). In Experiment 3 the problem schema activation was clearly separated from the goal information. In all three experiments, goal information availability was assessed by on-line measures. The results showed that participants processed situational information by keeping track of characters' goals. These results fit nicely with those studies that emphasize the role of situation model construction in word problem solving.

  9. Modeling the variations of Dose Rate measured by RAD during the first MSL Martian year: 2012-2014

    CERN Document Server

    Guo, Jingnan; Wimmer-Schweingruber, Robert F; Rafkin, Scot; Hassler, Donald M; Posner, Arik; Heber, Bernd; Koehler, Jan; Ehresmann, Bent; Appel, Jan K; Boehm, Eckart; Boettcher, Stephan; Burmeister, Soenke; Brinza, David E; Lohf, Henning; Martin, Cesar; Kahanpaeae, H; Reitz, Guenther

    2015-01-01

    The Radiation Assessment Detector (RAD), on board Mars Science Laboratory's (MSL) rover Curiosity, measures the {energy spectra} of both energetic charged and neutral particles along with the radiation dose rate at the surface of Mars. With these first-ever measurements on the Martian surface, RAD observed several effects influencing the galactic cosmic ray (GCR) induced surface radiation dose concurrently: [a] short-term diurnal variations of the Martian atmospheric pressure caused by daily thermal tides, [b] long-term seasonal pressure changes in the Martian atmosphere, and [c] the modulation of the primary GCR flux by the heliospheric magnetic field, which correlates with long-term solar activity and the rotation of the Sun. The RAD surface dose measurements, along with the surface pressure data and the solar modulation factor, are analysed and fitted to empirical models which quantitatively demonstrate} how the long-term influences ([b] and [c]) are related to the measured dose rates. {Correspondingly we ...

  10. Radioactivity measurements and dose rate calculations using ERICA tool in the terrestrial environment of Greece.

    Science.gov (United States)

    Sotiropoulou, Maria; Florou, Heleny; Manolopoulou, Metaxia

    2016-06-01

    In the present study, the radioactivity levels to which terrestrial non-human biota were exposed are examined. Organisms (grass and herbivore mammals) and abiotic components (soil) were collected during the period of 2010 to 2014 from grasslands where sheep and goats were free-range grazing. Natural background radionuclides ((226)Ra, (228)Ra, (228)Th) and artificial radionuclides ((137)Cs, (134)Cs, (131)I) were detected in the collected samples using gamma spectrometry. The actual measured activity concentrations and site-specific data of the studied organisms were imported in ERICA Assessment Tool (version 1.2.0) in order to provide an insight of the radiological dose rates. The highest activity concentrations were detected in samples collected from Lesvos island and the lowest in samples collected from Attiki and Etoloakarnania prefectures. The highest contribution to the total dose rate was clearly derived from the internal exposure and is closely related to the exposure to alpha emitters of natural background ((226)Ra and (228)Th). The Fukushima-derived traces of (137)Cs, (134)Cs, and (131)I, along with the residual (137)Cs, resulted in quite low contribution to the total dose rate. The obtained results may strengthen the adaptation of software tools to a wider range of ecosystems and may be proved useful in further research regarding the possible impact of protracted low level ionizing radiation on non-human biota. This kind of studies may contribute to the effective incorporation of dosimetry tools in the development of integrated environmental and radiological impact assessment policies.

  11. Surface activity distribution measurements and establishment of a dose rate map inside the destroyed Chernobyl reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chesnokov, A.V.; Fedin, V.I.; Gulyaev, A.A. [RECOM Ltd., Moscow (Russian Federation)] [and others

    1999-02-01

    A Gamma Locator designed for contamination survey inside the reactor hall of the 4th unit of Chernobyl NNP has been developed. The device consists of a detector head and a remote control computer connected by a 150 m long cable. The detector head (dimensions: 500 mm by 500 mm by 400 mm; weight: about 40 kg) is a collimated scintillation gamma detector (the collimation angle is 10 deg.). It is installed on a scanning unit and was placed inside the reactor hall. The Gamma Locator scans all surfaces of the reactor hall with angular steps ({<=} 1 deg. vertically as well as horizontally) and the particle fluence from the corresponding direction is recorded. The distance between the device head and the measured surface is instantaneously registered by a laser distance gauge. Inside the collimator there is a small CCD camera which makes it possible to obtain a visible image of the measured surface. The effective surface activity levels are presented in colour on the screen of the control computer. The gamma detector essentially consists of a CsI(TI) scintillator crystal ({phi} 8 mm in diameter, 2.5 mm in thickness) and a Si photodiode. The detector energy resolution is about 8% for radiation from {sup 137}Cs. The exposure dose rate distribution in the reactor hall is estimated from the measured effective surface activities ({sup 137}Cs is the main gamma emitting isotope inside the reactor hall). The results of dose rate calculations are presented in colour superposed on a drawing of the reactor hall. (au) 1 tab., 28 ills., 16 refs.

  12. Measurements of High Energy X-Ray Dose Distributions Using Multi-Dimensional Fiber-Optic Radiation Detectors

    Science.gov (United States)

    Jang, Kyoung Won; Cho, Dong Hyun; Shin, Sang Hun; Lee, Bongsoo; Chung, Soon-Cheol; Tack, Gye-Rae; Yi, Jeong Han; Kim, Sin; Cho, Hyosung

    In this study, we have fabricated multi-dimensional fiber-optic radiation detectors with organic scintillators, plastic optical fibers and photo-detectors such as photodiode array and a charge-coupled device. To measure the X-ray dose distributions of the clinical linear accelerator in the tissue-equivalent medium, we have fabricated polymethylmethacrylate phantoms which have one-dimensional and two-dimensional fiber-optic detector arrays inside. The one-dimensional and two-dimensional detector arrays can be used to measure percent depth doses and surface dose distributions of high energy X-ray in the phantom respectively.

  13. Measurement of staff doses in interventional procedures using LiF TL-detectors and a special diode dosemeter

    Energy Technology Data Exchange (ETDEWEB)

    Parviainen, T.; Toivonen, M.; Kosunen, A.; Karppinen, J. [Radiation and Nuclear Safety Authority, Helsinki (Finland); Ylitalo, A. [Satakunta Central Hospital, Division for Cardiology, Pori (Finland)

    2003-06-01

    Personal doses vary considerably among the operational staff in cardiac examination procedures and interventions. Correspondingly, the fluoroscopy time may vary from a few minutes to more than 1 hour. Large personal doses in the range of 35 - 41 mSv were registered to some interventional radiologists and cardiologists in 2001 in Finland. Measurement of doses per intervention from hands, shoulders and ankles (parts of the body outside the lead apron) are therefore of interest, but small and highly sensitive dosemeters have not been commonly available for reliable and practical measurements. Thermoluminescent detectors of LiF:MgCu,P are sensitive enough, but residual luminescence from previous uses of detectors and the dose collected from natural background radiation between preparation for use and readout may be significant sources of uncertainty. The company Unfors Instrumens AB (Billdal, Sweden) has designed a light weight diode dosemeter with long cables between detectors and the electronic part for simultaneous measurement of doses from various parts of the body. The aim of this work is to report doses of the operating staff per a cardiac examination or intervention and study the capabilities of the diode dosemeter in staff dose measurements. (orig.)

  14. Online single particle measurements of black carbon coatings, structure and optical properties

    Science.gov (United States)

    Allan, James; Liu, Dantong; Taylor, Jonathan; Flynn, Michael; Williams, Paul; Morgan, William; Whitehead, James; Alfarra, Rami; McFiggans, Gordon; Coe, Hugh

    2016-04-01

    The impacts of black carbon on meteorology and climate remain a major source of uncertainty, owing in part to the complex relationship between the bulk composition of the particulates and their optical properties. A particular complication stems from how light interacts with particles in response to the microphysical configuration and any 'coatings', i.e. non-black carbon material that is either co-emitted or subsequently obtained through atmospheric processing. This may cause the particle to more efficiently absorb or scatter light and may even change the sign of its radiative forcing potential. While much insight has been gained through measurements of bulk aerosol properties, either while suspended or after collection on a filter or impactor substrate, this does not provide a complete picture and thus may not adequately constrain the system. Here we present an overview of recent work to better constrain the properties of black carbon using online, in situ measurements of single particles, primarily using a Single Particle Soot Photometer (SP2). We have developed novel methods of inverting the data produced and combining the different metrics derived so as to give the most effective insights into black carbon sources, processes and properties. We have also used this measurement in conjunction with other instruments (sometimes in series) and used the data to challenge many commonly used models of optical properties such as core-shell Mie, Rayleigh-Debeye-Gans and effective medium. This work has been carried out in a variety of atmospheric environments and with laboratory-produced soots, e.g. from a diesel engine rig. Highlights include the finding that with real-world atmospheric aerosols, bulk optical measurements may be insufficient to derive brown carbon parameters without detailed morphological data. We also show that the enhancement of absorption for both ambient and laboratory generated particles only occurs after the coating mass fraction reaches a certain

  15. Dose Measurements on the BION-M1 satellite applying passive detector packages

    Science.gov (United States)

    Stradi, Andrea; Berger, Thomas; Kodaira, Satoshi; Kubancak, Jan; Palfalvi, Jozsef K.; Ambrozova, Iva; Tolochek, Raisa; Shurshakov, Vyacheslav; Szabo, Julianna

    A passive detector package was developed in the past years in the Centre for Energy Research, Hungarian Academy of Science to detect cosmic ray particles, to determine their flux and dose. It consists of thermoluminescent detectors (TLD) and plastic solid state nuclear track detectors (SSNTD). In the frame of a scientific co-operation between the Institute for Biomedical Problems (IBMP) fourteen packages were flow within the new BION-M1 satellite program together with biological samples and detector packages from other participants. Two packages were located outside and the rest ones inside the recoverable capsule. Comparing to the previous BION and similar FOTON experiments, (all together 17 successful ones), this flight was a “champion” with the highest altitude (575 km), orbital inclination (64.9°) and flight duration (30 days). The external exposure provided a unique possibility to study not only the elevated level of cosmic rays but also the behavior of the detector packages in extreme circumstances as low temperature and pressure. The paper will summarize the construction of the detector packages, the calibration and evaluation processes, as well as, the linear energy transfer (LET) spectra, the absorbed dose and the mean quality factor. These quantities will be compared taking into consideration their location inside and outside the capsule and to the results of other participants. Also some comparison of results to the previous BION and FOTON flights and contemporary measurements on the ISS will be presented.

  16. Influence of thermoluminescent dosimeters energy dependence on the measurement of entrance skin dose in radiographic procedures

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Mercia Liane de; Galindo, Renata Sales; Hazin, Clovis Abrahao, E-mail: mercial@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN/NE-CNEN/PE), Recife, PE (Brazil); Maia, Ana Figueiredo [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Fisica; Nascimento, Natalia Cassia do Espirito Santo; Fragoso, Maria da Conceicao de Farias [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2010-04-15

    Objective: this study was aimed at evaluating the influence of the energy dependence of thermoluminescent materials on the determination of entrance skin dose in patients submitted to conventional radiographic studies (general radiology, mammography and dental radiology). Materials and methods: three different thermoluminescent materials were utilized: LiF:Mg,Ti, LiF:Mg,Cu,P and CaSO{sub 4}:Dy. These materials were exposed to standardized sources of X and gamma radiation and clinical X-ray beams. Results: calibration and energy dependence curves were obtained. All the materials showed a linear response as a function of the air kerma. As far as energy dependence is concerned, the CaSO{sub 4}:Dy and LiF:Mg,Ti samples showed the greatest variation on thermoluminescent responses as a function of the effective radiation beam. Conclusion: the tested materials showed an appropriate performance for detecting X radiation on standard and clinical X-ray beams. Although CaSO{sub 4}:Dy and LiF:Mg,Ti samples present a significant energy dependence in the considered energy range, these materials can be utilized for measuring entrance skin doses, provided appropriate correction factors are applied (author)

  17. DOSE MEASURMENT IN ULTRAVIOLET DISINFECTION OF WATER AND WASTE WATER BY CHEMICAL METHOD

    Directory of Open Access Journals (Sweden)

    F.Vaezi

    1995-06-01

    Full Text Available Chemical methods ( actinometry depend on the measurement of the extent to which a chemical reaction occurs under the influence of UV light. Two chemical actinometers have been used in this research. In one method, the mixtures of potassium peroxidisuiphate butanol solutions were irradiated for various time intervals, and pH-changes were determined. A linear relationship was observed between these changes and UV-dose applied. In another method, the acidic solutions of ammonium molybdate and ethyl alcohol were irradiated and the intensity of blue color developed was determined by titration with potassium permanganate solutions. The volumes of titrant used were then plotted versus the UV-doses. This showed a linear relationship which could be used for dosimeiry. Both of these actometers proved to be reliable. The first is the method of choice with a view to have much accuracy and the second method is preferred because of its feasibility and having advantages of no need to any equipment and non-accessible raw materials.

  18. The online measured black carbon aerosol and source orientations in the Nam Co region, Tibet.

    Science.gov (United States)

    Zhang, Xin; Ming, Jing; Li, Zhongqin; Wang, Feiteng; Zhang, Guoshuai

    2017-09-17

    Equivalent black carbon (eBC) mass concentrations were measured by an aethalometer (AE-31) in the Nam Co, central Tibet from 2010 to 2014. Different from previous filter-sampling studies (Ming et al., J Environ Sci 22(11):1748-1756, 2010; Zhao et al., Environ Sci Pollut Res 20:5827-5838, 2013), the first high-resolution online eBC measurement conducted in central Tibet is reported here, allowing to discuss the diurnal variations as well as seasonal variabilities of eBC. Average daily eBC concentration was 74 ± 50 ng/m(3), reflecting a global background level. Meteorological conditions influenced eBC concentrations largely at seasonal scale, which are higher in February-May but lower in June-January. The highest eBC concentrations (greater than 210 ng/m(3)) were more associated with the W and WSW winds smaller than 6 m/s. The diurnal variations of eBC showed plateaus from 10:00 to 15:00 with seasonal variations, associated with local anthropogenic activities, such as indigenous Tibetan burning animal waste and tourism traffic. The PBLHs showed a co-variance with eBC concentrations, implicating close sources. The aerosol optical depths derived from the MODIS data over the Nam Co Observatory Station (NCOS)-included sub-area (30° N-40° N, 90° E-100° E) showed significant relationship with eBC concentrations. This suggests that nearby or short-distance sources other than long-distance transported pollutants could be important contributors to eBC concentrations at the NCOS, different from the conclusions suggested by previous studies.

  19. SU-E-T-443: Developmental Technique for Proton Pencil Beam Measurements: Depth Dose

    Energy Technology Data Exchange (ETDEWEB)

    Arjomandy, B; Lee, T; Schultz, T; Hsi, W; Park, S [McLaren Cancer Institute, Flint, MI (United States)

    2014-06-01

    Purpose: Measurements of depth dose distribution (DDD) of pencil beam in proton therapy can be challenging and time consuming. We have developed a technique that uses two Bragg peak chambers to expedite these measurements with a high accuracy. Methods and Material: We used a PTW water tank and two PTW 10.5 cm3 Bragg peak chambers; one as a field chamber and the other as a reference chamber to measure DDDs for 100–250 MeV proton pencil beams. The reference chamber was positioned outside of the water tank upstream with respect to field chamber. We used Geant4 Monte Carlo Simulation (MCS) to model the ProTom proton beam to generate DDDs. The MCS generated DDDs were used to account for halo effects of proton pencil beam that are not measureable with Bragg peak chambers. We also used PTW PEAKFINDER to measure DDDs for comparison purpose. Results: We compared measured and MCS DDDs with Continuous Slowing Down Approximation (CSDA) ranges to verify the range of proton beams that were supplied by the manufacturer. The agreements between all DDD with respect to CSDA were within ±0.5 mm. The WET for Bragg peak chamber for energies between 100–250 MeV was 12.7 ± 0.5 mm. The correction for halo effect was negligible below 150 MeV and was in order of ∼5-10% for 150–250 MeV. Conclusion: Use of Bragg Peak chamber as a reference chamber can facilitate DDD measurements in proton pencil beam with a high accuracy. Some corrections will be required to account for halo effect in case of high energy proton beams due to physical size of chamber.

  20. Comparison of measured and calculated dose rates near nuclear medicine patients.

    Science.gov (United States)

    Yi, Y; Stabin, M G; McKaskle, M H; Shone, M D; Johnson, A B

    2013-08-01

    Widely used release criteria for patients receiving radiopharmaceuticals (NUREG-1556, Vol. 9, Rev.1, Appendix U) are known to be overly conservative. The authors measured external exposure rates near patients treated with I, Tc, and F and compared the measurements to calculated values using point and line source models. The external exposure dose rates for 231, 11, and 52 patients scanned or treated with I, Tc, and F, respectively, were measured at 0.3 m and 1.0 m shortly after radiopharmaceutical administration. Calculated values were always higher than measured values and suggested the application of "self-shielding factors," as suggested by Siegel et al. in 2002. The self-shielding factors of point and line source models for I at 1 m were 0.60 ± 0.16 and 0.73 ± 0.20, respectively. For Tc patients, the self-shielding factors for point and line source models were 0.44 ± 0.19 and 0.55 ± 0.23, and the values were 0.50 ± 0.09 and 0.60 ± 0.12, respectively, for F (all FDG) patients. Treating patients as unshielded point sources of radiation is clearly inappropriate. In reality, they are volume sources, but treatment of their exposures using a line source model with appropriate self-shielding factors produces a more realistic, but still conservative, approach for managing patient release.

  1. Spectrum-dose conversion operator of NaI(Tl) and CsI(Tl) scintillation detectors for air dose rate measurement in contaminated environments.

    Science.gov (United States)

    Tsuda, Shuichi; Saito, Kimiaki

    2017-01-01

    Spectrum-dose conversion operators, the G(E) functions, for common NaI(Tl) scintillation survey meters and CsI(Tl) detectors are obtained for measurements in a semi-infinite plane of contaminated ground field by photon-emitting radionuclides (ground source). The calculated doses at a height of 100 cm from the ground in (137)Cs-contaminated environments by the Monte Carlo simulation technique are compared with those obtained using the G(E) functions by assuming idealized irradiation geometries such as anterior-posterior or isotropic. The simulation reveals that one could overestimate air dose rates in the environment by a maximum of 20-30% for NaI(Tl) detectors and 40-50% for CsI(Tl) detectors depending on photon energy when using the G(E) functions assuming idealized irradiation geometries for ground source measurements. Measurements obtained after the nuclear accident in Fukushima reveal that the doses calculated using a G(E) function for a unidirectional irradiation geometry are 1.17 times higher than those calculated using a G(E) function for the ground source in the case of a CsI(Tl) scintillation detector, which has a rectangular parallelepiped crystal (13 × 13 × 20 mm(3)). However, if a G(E) function is used assuming irradiation to a surface of the detector, the doses agree with those of the ground source within 2%. These results indicate that in contaminated environments, the commonly used scintillation-based detectors overestimate doses within the acceptable limit. In addition, the degree of overestimation depends on the irradiation direction of each detector assumed for developing the G(E) function. With regard to directional dependence of the detectors, reliable air dose rates in the environment can be obtained using the G(E) function determined in unidirectional irradiation geometry, provided that the irradiation surface of the crystal is determined properly. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Impulsivity in Multiplayer Online Battle Arena Gamers: Preliminary Results on Experimental and Self-Report Measures

    OpenAIRE

    Nuyens, F; Deleuze, J; Maurage, P; Griffiths, MD; Kuss, DJ; Billieux, J

    2016-01-01

    Background and aims: Multiplayer Online Battle Arena (MOBA) games have become the most popular type of video games played worldwide, superseding the playing of Massively Multiplayer Online Role-Playing Games and First-Person Shooter games. However, empirical studies focusing on the use and abuse of MOBA games are still very limited, particularly regarding impulsivity, which is an indicator of addictive states but has not yet been explored in MOBA games. In this context, the objective of the p...

  3. CORRELATION OF LOCAL FAILURE WITH MEASURES OF DOSE INSUFFICIENCY IN THE HIGH-DOSE SINGLE-FRACTION TREATMENT OF BONY METASTASES

    Science.gov (United States)

    Lovelock, D. Michael; Zhang, Zhigang; Jackson, Andrew; Keam, Jennifer; Bekelman, Justin; Bilsky, Mark; Lis, Eric; Yamada, Yoshiya

    2011-01-01

    Purpose In the setting of high-dose single-fraction image-guided radiotherapy of spine metastases, the delivered dose is hypothesized to be a significant factor in local control. We investigated the dependence of local control on measures of dose insufficiency. Methods and Materials The minimum doses received by the hottest 100%, 98%, and 95% (Dmin, D98, and D95) of the gross target volume (GTV) were computed for 91 consecutively treated lesions observed in 79 patients. Prescribed doses of 18–24 Gy were delivered in a single fraction. The spinal cord and cauda equina were constrained to a maximum dose of 12–14 Gy and 16 Gy, respectively. A rank-sum test was used to assess the differences between radiographic local failure and local control. Results With a median follow-up of 18 months, seven local failures have occurred. The distributions of GTV Dmin, D98, and D95 for treatments resulting in local failure were found to be statistically different from the corresponding distributions of the patient group as a whole. Taking no account of histology, p values calculated for Dmin, D98, and D95 were 0.004, 0.012, and 0.031, respectively. No correlations between local failure and target volume or between local failure and anatomic location were found. Conclusions The results indicate that Dmin, D98, and D95 may be important risk factors for local failure. No local failures in any histology were observed when Dmin was >15 Gy, suggesting that this metric may be an important predictor of local control. PMID:20350795

  4. What Drives Students to Complete Online Courses? What Drives Faculty to Teach Online? Validating a Measure of Motivation Orientation in University Students and Faculty

    Science.gov (United States)

    Johnson, Ruth; Stewart, Cindy; Bachman, Christine

    2015-01-01

    Although online student enrollment has shown double digit growth for almost a decade and academic leaders recognize that online education is necessary for enrollment growth, little is known about what motivates students to enroll in or faculty to teach face-to-face (F2F) versus online courses. The psychometric properties of a motivation scale were…

  5. What Drives Students to Complete Online Courses? What Drives Faculty to Teach Online? Validating a Measure of Motivation Orientation in University Students and Faculty

    Science.gov (United States)

    Johnson, Ruth; Stewart, Cindy; Bachman, Christine

    2015-01-01

    Although online student enrollment has shown double digit growth for almost a decade and academic leaders recognize that online education is necessary for enrollment growth, little is known about what motivates students to enroll in or faculty to teach face-to-face (F2F) versus online courses. The psychometric properties of a motivation scale were…

  6. Process Analytical Technology and On-Line Spectroscopic Measurements of Chemical Meat Quality

    DEFF Research Database (Denmark)

    Sørensen, Klavs Martin

    This thesis deals with process analytical technology and how it can be implemented in the meat industry through on-line grading of chemical meat quality. The focus will be on two applications, namely the rapid quality control of fat quality and the development of a method for on-line detection of...... quality, but also with environmental issues such as energy and water use and animal welfare. Future research into the technologies will ultimately allow broad on-line screening of biomarkers, leading to on-line metabolomics......This thesis deals with process analytical technology and how it can be implemented in the meat industry through on-line grading of chemical meat quality. The focus will be on two applications, namely the rapid quality control of fat quality and the development of a method for on-line detection...... of boar taint. The chemical makeup of fat has a large effect on meat cut quality. Fat quality has traditionally been determined by methylation of a tissue sample followed by chromatography on a GC-MS system, elucidating the composition of the individual fatty acids. As this procedure typically takes far...

  7. Total dose incurred by patients and staff from BMD measurement using a new 2D digital bone densitometer.

    Science.gov (United States)

    Boudousq, V; Kotzki, P O; Dinten, J M; Barrau, C; Robert-Coutant, C; Thomas, E; Goulart, D Mariano

    2003-05-01

    Dual energy X-ray absorptiometry (DXA) is a widely used and precise technique for non-invasive assessment of bone mineral density. The DXA systems have evolved from pencil X-ray beam (single detector) to fan beam (linear array detector) and recently cone beam densitometers (bi-dimensional detector), allowing for an examination to occur without any scanning and with a short acquisition time. The purpose of this study was to evaluate patient and staff dose from a new cone beam densitometer, the DMS Lexxos. Measurements were performed on a DMS Lexxos bone densitometer prototype. An anthropomorphic phantom and thermoluminescent dosimeters were used to evaluate the effective dose. Ionization chambers and electronic personal dosimeters were used to evaluate the staff dose. The effective dose is 8.4 micro Sv for an anteroposterior spine examination and 4.8 micro Sv for a femoral neck in standard mode. The averaged scattered dose rate (ambient dose equivalent) at 1 m from the beam is evaluated at 226 micro Sv/h. Assuming six patients per hour with two views per patient, the time averaged dose rate is evaluated at 2.9 micro Sv/h. By the personal dosimeter, the staff dose (Hp 10) at 1 m from the beam is evaluated at 0.23 micro Sv per examination. For one examination, patient and staff dose from this new technology remains low: in the same range as the fan-beam densitometer.

  8. Characterization of a fiber-coupled Al2O3:C luminescence dosimetry system for online in vivo dose verification during Ir-192 brachytherapy

    DEFF Research Database (Denmark)

    Andersen, Claus Erik; Nielsen, Søren Kynde; Greilich, Steffen

    2009-01-01

    . The reproducibility (one standard deviation) for RL and OSL measurements was 1.3%. The measured depth-dose profiles agreed well with the theoretical expectations computed with the EGSNRC Monte Carlo code, suggesting that the energy dependence for the dosimeter probes (relative to water) is less than 6% for source......-to-probe distances in the range of 2-50 mm. Under certain conditions, the RL signal could be greatly disturbed by the so-called stem signal (i.e., unwanted light generated in the fiber cable upon irradiation). The OSL signal is not subject to this source of error. The tested system appears to be adequate for in vivo...

  9. Minimal erythema dose and minimal melanogenesis dose relate better to objectively measured skin type than to Fitzpatricks skin type

    DEFF Research Database (Denmark)

    Wulf, Hans Christian; Philipsen, Peter A; Ravnbak, Mette H

    2010-01-01

    Fitzpatrick skin type (FST I-IV) is a subjective expression of ultraviolet (UV) sensitivity based on erythema and tanning reactivity after a single exposure. Pigment protection factor (PPF) is an objective measurement of skin sensitivity in all skin types after a single exposure....

  10. Minimal erythema dose and minimal melanogenesis dose relate better to objectively measured skin type than to Fitzpatricks skin type

    DEFF Research Database (Denmark)

    Wulf, Hans Christian; Philipsen, Peter A; Ravnbak, Mette H

    2010-01-01

    Fitzpatrick skin type (FST I-IV) is a subjective expression of ultraviolet (UV) sensitivity based on erythema and tanning reactivity after a single exposure. Pigment protection factor (PPF) is an objective measurement of skin sensitivity in all skin types after a single exposure....

  11. SU-F-SPS-03: Direct Measurement of Organ Doses Resulting From Head and Cervical Spine Trauma CT Protocols

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, C; Lipnharski, I; Quails, N; Correa, N; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: This retrospective study analyzes the exposure history of emergency department (ED) patients undergoing head and cervical spine trauma computed tomography (CT) studies. This study investigated dose levels received by trauma patients and addressed any potential concerns regarding radiation dose issues. Methods: Under proper IRB approval, a cohort of 300 trauma cases of head and cervical spine trauma CT scans received in the ED was studied. The radiological image viewing software of the hospital was used to view patient images and image data. The following parameters were extracted: the imaging history of patients, the reported dose metrics from the scanner including the volumetric CT Dose Index (CTDIvol) and Dose Length Product (DLP). A postmortem subject was scanned using the same scan techniques utilized in a standard clinical head and cervical spine trauma CT protocol with 120 kVp and 280 mAs. The CTDIvol was recorded for the subject and the organ doses were measured using optically stimulated luminescent (OSL) dosimeters. Typical organ doses to the brain, thyroid, lens, salivary glands, and skin, based on the cadaver studies, were then calculated and reported for the cohort. Results: The CTDIvol reported by the CT scanner was 25.5 mGy for the postmortem subject. The average CTDIvol from the patient cohort was 34.1 mGy. From these metrics, typical average organ doses in mGy were found to be: Brain (44.57), Thyroid (33.40), Lens (82.45), Salivary Glands (61.29), Skin (47.50). The imaging history of the cohort showed that on average trauma patients received 26.1 scans over a lifetime. Conclusion: The average number of scans received on average by trauma ED patients shows that radiation doses in trauma patients may be a concern. Available dose tracking software would be helpful to track doses in trauma ED patients, highlighting the importance of minimizing unnecessary scans and keeping doses ALARA.

  12. Comparison of passive and active radon measurement methods for personal occupational dose assessment

    Directory of Open Access Journals (Sweden)

    Hasanzadeh Elham

    2016-01-01

    Full Text Available To compare the performance of the active short-term and passive long-term radon measurement methods, a study was carried out in several closed spaces, including a uranium mine in Iran. For the passive method, solid-state nuclear track detectors based on Lexan polycarbonate were utilized, for the active method, AlphaGUARD. The study focused on the correlation between the results obtained for estimating the average indoor radon concentrations and consequent personal occupational doses in various working places. The repeatability of each method was investigated, too. In addition, it was shown that the radon concentrations in different stations of the continually ventilated uranium mine were comparable to the ground floor laboratories or storage rooms (without continual ventilation and lower than underground laboratories.

  13. CVD diamond wafers as large-area thermoluminescence detectors for measuring the spatial distribution of dose

    Science.gov (United States)

    Marczewska, B.; Bilski, P.; Olko, P.; Olko, P.; Nesládek, M.; Bergonzo, P.; Rbisz, M.; Waligórski, M. P. R.

    2003-09-01

    The applicability of large-area CVD diamond wafers (diameter about 5 cm, thickness about 0.1 mm), read out as thermoluminescence (TL) detectors, for assessing two-dimensional (2-D) dose distribution over their area, was investigated. To obtain 2-D TL images, a special TL reader equipped with large-area planchet and a CCD camera instead of the usual PM tube was developed. Several 2-D TL images: of an alpha source (Am-241), a Ra-226 needle source and a Ru-106 ophthalmic applicator, were measured and high-resolution digital images obtained. Our preliminary results demonstrate the potential capability of large-area CVD diamond wafers, read out as TL detectors, in 2-D dosimetry for medical applications. (

  14. Measurements of air dose rates in and around houses in the Fukushima Prefecture in Japan after the Fukushima accident.

    Science.gov (United States)

    Matsuda, Norihiro; Mikami, Satoshi; Sato, Tetsuro; Saito, Kimiaki

    2017-01-01

    Measurements of air dose rates for 192 houses in a less contaminated area (radiation cannot be neglected when we consider dose reduction factors in less contaminated areas. The reductions in indoor dose rates are observed because a patch of ground under each house is not contaminated (this is the so-called uncontaminated effect) since the shielding capability of light construction materials is typically low. For reinforced steel-framed concrete houses (classed as heavy), the dose rates inside the houses did not show a correlation with those outside the houses due to the substantial shielding capability of these materials. The average indoor dose rates were slightly higher than the arithmetic mean value of the outdoor dose rates from the natural background because concrete acts as a source of natural radionuclides. The characteristics of the uncontaminated effect were clarified through Monte Carlo simulations. It was found that there is a great variation in air dose rates even within one house, depending on the height of the area and its closeness to the outside boundary. Measurements of outdoor dose rates required consideration of local variations depending on the environment surrounding each house. The representative value was obtained from detailed distributions of air dose rates around the house, as measured by a man-borne survey. Therefore, it is imperative to recognize that dose reduction factors fluctuate in response to various factors such as the size and shape of a house, construction materials acting as a shield and as sources, position (including height) within a room, floor number, total number of floors, and surrounding environment.

  15. Radiochromic film for dosimetric measurements in radiation shielding composites synthesized for applied in radiology procedures of high dose

    Energy Technology Data Exchange (ETDEWEB)

    Fontainha, C. C. P. [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Baptista N, A. T.; Faria, L. O., E-mail: crissia@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    Full text: Medical radiology offers great benefit to patients. However, although specifics procedures of high dose, as fluoroscopy, Interventional Radiology, Computed Tomography (CT) make up a small percent of the imaging procedures, they contribute to significantly increase dose to population. The patients may suffer tissue damage. The probability of deterministic effects incidence depends on the type of procedure performed, exposure time, and the amount of applied dose at the irradiated area. Calibrated radiochromic films can identify size and distribution of the radiated fields and measure intensities of doses. Radiochromic films are sensitive for doses ranging from 0.1 to 20 c Gy and they have the same response for X-rays effective energies ranging from 20 to 100 keV. New radiation attenuators materials have been widely investigated resulting in dose reduction entrance skin dose. In this work, Bi{sub 2}O{sub 3} and ZrO{sub 2}:8 % Y{sub 2}O{sub 3} composites were obtained by mixing them with P(VDF-Tr Fe) copolymers matrix from casting method and then characterized by Ftir. Dosimetric measurements were obtained with Xr-Q A2 Gafchromic radiochromic films. In this setup, one radiochromic film is directly exposed to the X-rays beam and another one measures the attenuated beam were exposed to an absorbed dose of 10 mGy of RQR5 beam quality (70 kV X-ray beam). Under the same conditions, irradiated Xr-Q A2 films were stored and scanned measurement in order to obtain a more reliable result. The attenuation factors, evaluated by Xr-Q A2 radiochromic films, indicate that both composites are good candidates for use as patient radiation shielding in high dose medical procedures. (Author)

  16. Typical exposure parameters, organ doses and effective doses for endovascular aortic aneurysm repair: Comparison of Monte Carlo simulations and direct measurements with an anthropomorphic phantom

    Energy Technology Data Exchange (ETDEWEB)

    Foerth, Monika; Treitl, Karla Maria; Treitl, Marcus [Ludwig Maximilians University of Munich, Institute for Clinical Radiology, Munich (Germany); Seidenbusch, Michael C. [Ludwig Maximilians University of Munich, Institute for Clinical Radiology, Munich (Germany); Clinical Centre of the Ludwig Maximilian University of Munich, Institute for Clinical Radiology, Munich (Germany); Sadeghi-Azandaryani, Mojtaba [Clinical Centre of the County of Erding, Department of Vascular Surgery, Erding (Germany); Lechel, Ursula [Federal Office for Radiation Protection, Department of Medical and Occupational Radiation Protection, Oberschleissheim (Germany)

    2015-09-15

    Radiation exposure of patients during endovascular aneurysm repair (EVAR) procedures ranks in the upper sector of medical exposure. Thus, estimation of radiation doses achieved during EVAR is of great importance. Organ doses (OD) and effective doses (ED) administered to 17 patients receiving EVAR were determined (1) from the exposure parameters by performing Monte Carlo simulations in mathematical phantoms and (2) by measurements with thermoluminescent dosimeters in a physical anthropomorphic phantom. The mean fluoroscopy time was 26 min, the mean dose area product was 24995 cGy cm2. The mean ED was 34.8 mSv, ODs up to 626 mSv were found. Whereas digital subtraction angiographies (DSA) and fluoroscopies each contributed about 50 % to the cumulative ED, the ED rates of DSAs were found to be ten times higher than those of fluoroscopies. Doubling of the field size caused an ED rate enhancement up to a factor of 3. EVAR procedures cause high radiation exposure levels that exceed the values published thus far. As a consequence, (1) DSAs should be only performed when necessary and with a low image rate, (2) fluoroscopies should be kept as short as possible, and (3) field sizes should be minimized. (orig.)

  17. Absorbed Dose in Ion Beams: Comparison of Ionization and Fluence-based Measurements

    CERN Document Server

    Osinga, Julia-Maria; Bartz, James A; Akselrod, Mark S; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    We present a direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionization chamber. Irradiations were performed at the Heidelberg Ion-Beam Therapy Center (HIT) using monoenergetic protons (142.66 MeV, 3x10^6 1/cm2) and carbon ions (270.55 MeV/u, 3x10^6 1/cm2) in the entrance channel of the ion beam. We found that absorbed dose to water values as determined by fluence measurements using FNTDs are in case of protons in good agreement (2.2 %) with ionization chamber measurements when including slower protons and Helium secondaries by an effective stopping power. For carbon, however, we found a discrepancy of 4.6 %. This deviation is significant considering both the uncertainties for ionization chambers as given in the TRS 398 and from experimental design (e.g. inhomogeneous irradiation, machine stability, beam direction). Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not seen.

  18. Evaluation and measurements of radioactive air emission and off-site doses at SLAC.

    Science.gov (United States)

    Chan, Ivy; Liu, James; Tran, Henry

    2013-08-01

    SLAC, a high-energy (GeV) electron accelerator facility, performs experimental and theoretical research using high-energy electron and/or positron beams that can produce secondary neutron and gamma radiation when beam losses occur. Radioactive gas production (mainly C, N, O, Ar) and release is one of the environmental protection program issues. U.S. DOE Order 458.1 requires that 40 CFR 61 Subpart H's NESHAP requirements be followed. These regulations prescribe a total dose limit of 0.1 mSv y to the Maximally Exposed Individual (MEI) of the general public, a requirement for a continuous air monitoring system if a release point within a facility can cause > 1 × 10 mSv y to the MEI, and a requirement for periodic confirmatory measurements for minor sources which give releases that contribute ≤ 1 × 10 mSv y to the MEI. At SLAC, all air release points for current operations are evaluated to be minor sources. This paper describes SLAC's evaluation following NESHAP requirements; measurements using the Air Monitoring Station (AMS) as periodic confirmatory measurements are also discussed.

  19. Emission rate estimation through data assimilation of gamma dose measurements in a Lagrangian atmospheric dispersion model.

    Science.gov (United States)

    Tsiouri, V; Kovalets, I; Andronopoulos, S; Bartzis, J G

    2012-01-01

    This paper presents an efficient algorithm for estimating the unknown emission rate of radionuclides in the atmosphere following a nuclear accident. The algorithm is based on assimilation of gamma dose rate measured data in a Lagrangian atmospheric dispersion model. Such models are used in the framework of nuclear emergency response systems (ERSs). It is shown that the algorithm is applicable in both deterministic and stochastic modes of operation of the dispersion model. The method is evaluated by computational simulations of a 3-d field experiment on atmospheric dispersion of ⁴¹Ar emitted routinely from a research reactor. Available measurements of fluence rate (photons flux) in air are assimilated in the Lagrangian dispersion model DIPCOT and the ⁴¹Ar emission rate is estimated. The statistical analysis shows that the model-calculated emission rates agree well with the real ones. In addition the model-predicted fluence rates at the locations of the sensors, which were not used in the data assimilation procedure are in better agreement with the measurements. The first evaluation results of the method presented in this study show that the method performs satisfactorily and therefore it is applicable in nuclear ERSs provided that more comprehensive validation studies will be performed.

  20. Online data base of satellite sounder and insitu measurements covering two solar cycles

    Science.gov (United States)

    Bilitza, D.; Reinisch, B.; Benson, R.; Grebowsky, J.; Papitashvili, N.; Huang, X.; Schar, W.; Hills, K.

    Accurate descriptions of the solar cycle variations of ionospheric parameters are an important goal of ionospheric modeling. Reliable predictions of these variations are of essential importance for almost all applications of ionospheric models. Unfortunately there are very few global data sources that cover a solar cycle or more. In an effort to expand the solar cycle coverage of data readily available for ionospheric modeling, we have processed a large number of satellite data sets from the sixties, seventies, and early eighties and have made them online accessible as part of NSSDC's ftp archive (http://nssdcftp.gsfc.nasa.gov/spacecraft data/) and it's ATMOWeb retrieval and plotting system (http://nssdc.gsfc.nasa.gov/atmoweb/). We report about two data restoration efforts supported through NASA's Applied Information Systems Research Program (AISRP). The first project deals with insitu data from a large number of US, Canadian, Japanese and German satellites that measured ionospheric densities and temperatures from 1964 to 1983. The accumulated data base includes data from the BE-B, DME-A, AE-B, Alouette 2, ISIS 1, 2, OGO-6, AEROS A, AE-C, -D, -E, Hinotori, ISS-b and DE-2 satellite missions. The second project involves the production of digital topside sounder ionograms from the ISIS 1 and 2 satellites and their subsequent inversion to produce electron-density profiles. Approximately 340,000 ionograms are available from NSSDC as of July 2002. An automatic topside ionogram scaler with true height algorithm (TOPIST) was developed as part of this project and is now being used to obtain electron density profiles from these ionograms. Providing global coverage over more than two solar cycles the database established by this two projects is a valuable asset for improvements of the International Reference Ionosphere model and for ionospheric research.

  1. A realtime, online automated system for measurement of Phosphate ions in atmospheric particles

    Science.gov (United States)

    Violaki, Kalliopi; Fang, Ting; Mihalopoulos, Nikos; Weber, Rodney James; Nenes, Athanasios

    2016-04-01

    Primary productivity of continental and marine ecosystems is often limited or co-limited by phosphorus. Of particular interest is the role of phosphorus in marine primary productivity, owing to its potential for affecting the concentration of atmospheric carbon dioxide. The atmosphere is considered a principal source of externally-supplied nutrients for large areas of the surface ocean, and oligotrophic open oceans in particular. Atmospheric inorganic P species (e.g. mono- or diprotonated orthophosphate) comprise the most bioavailable P form, and have been studied for many decades. Nevertheless, there are very large uncertainties in the phosphate biogeochemical budget due to the lack of observations and the poor match of the model to observations. This study presents a novel automated on-line, real-time analytical method for the analysis of water-soluble PO4-3 ions in atmospheric particles. The instrumentation consists of a particle-into-liquid sampler (PILS) coupled with a reaction coil to allow reagents to interact with the PILS liquid flow; the composite flow is then introduced into a mini spectrophotometer, which is equipped with a long path length of 250cm Liquid Wavequide Capillary Cell (LWCC), achieving low detection limit. This new system overcomes the limitations on detection and time resolution, as the configuration presented allows for measurement with 8 minute resolution. The data, when combined with routine PILS-IC or aerosol mass spectrometry, allows for an unprecedented insight towards the drivers of phosphate solubility and its relation to acidification from atmospheric acids. We present results for concentration of PM2.5 PO4-3 in Atlanta Georgia for a 2 month period (February-March, 2015) and the Eastern Mediterranean and its relation to aerosol acidity and other meteorological parameters. The results are discussed together with future directions towards optimized performance during long periods of operation.

  2. Volumic activities measurements and equivalent doses calculation of indoor 222Rn in Morocco

    Directory of Open Access Journals (Sweden)

    Abdelmajid Choukri

    2015-09-01

    Full Text Available Purpose: As a way of prevention, we have measured the volumic activities of indoor 222Rn and we have calculated the corresponding effective dose in some dwellings and enclosed areas in Morocco. Seasonal variation of Radon activities and Relationships between variation of these activities and some parameters such height, depth and type of construction were also established in this work.Methods: The passive time-integrated method of using a solid state nuclear track detector (LR-115 type II was employed. These films, cut in pieces of 3.4 ´ 2.5 cm2, were placed in detector holders and enclosed in heat-scaled polyethylene bags.Results: The measured volumic activities of radon vary in houses, between 31 and 136 Bq/m3 (0.55 and 2.39 mSv/year with an average value of 80 Bq/m3 (1.41 mSv/year. In enclosed work area, they vary between 60 Bq/m3 (0.38 mSv/year in an ordinary area to 1884 Bq/m3 (11.9 mSv/year at not airy underground level of 12 m. the relatively higher volumic activities of 222Rn in houses were measured in Youssoufia and khouribga towns situated in regions rich in phosphate deposits. Measurements at the geophysical observatory of Berchid show that the volumic activity of radon increases with depth, this is most probably due to decreased ventilation. Conclusion: The obtained results show that the effective dose calculated for indoor dwellings are comparable to those obtained in other regions in the word. The risks related to the volumic activities of indoor radon could be avoided by simple precautions such the continuous ventilation. The reached high value of above 1884 Bq/m3 don't present any risk for workers health in the geophysical observatory of Berchid because workers spend only a few minutes by day in the cellar to control and reregister data.

  3. Research on Influential Factors Analysis and Uncertainty Evaluation About Connected Liquid Level Sensor System Online Measuring Method

    Science.gov (United States)

    Geng, L.; Liu, J.

    The accuracy of damage alarming and damage identification of bridge structural and the reliability of reliability evaluation and the fatigue life evaluation depend on the data of sensor. At present, sample calibration is only done hi the initial installation of sensors of the sensing system for long-term monitoring of the bridge and generally is not done in using. So whether the system is stable and reliable is unable to be known. In this paper, on the model of connected liquid level sensor system, value traceability approach of sensor system online measuring method is studied by the field experiment and theory research based on technical index of measurement (output displacement) proposed by output parameters of integrated deflection sensing system. Applicable connected liquid level sensor system online measuring method is established and influential factors and the uncertainty are analyzed. Finally the applicable scope of the method is obtained. This paper has made the beneficial exploration on online measurement of the instrument after the installation of the bridge health monitoring system.

  4. IMRT and IMRS Checking the Dose Distribution in the Small Field Evaluation of Measurement by Changes in SAD

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Seung Young; Kim, Sung Joon; Park, Gir Yong; Son, Mi Suk; Lee, Nam Ki; Kim, Jin Soo [Dept. of Radiation Oncology, CHA Bundang medical Center, Seongnam (Korea, Republic of)

    2010-03-15

    It is very important to confirm conformance of dose distribution that is formed with treatment planning from IMRS or IMRT. It has been a problem dropped accuracy and conformance when the field size is getting smaller because of character of the 2D ion chamber. Verification of MatriXX Phantom dose distribution with a change in the SAD. Dose distribution measurement and analysis to improve the accuracy and should be useful to evaluate the award. A use of Novalis linear accelerator 6 MV photon beams. In general, IMRS were 25 patients with small field size. The selected patients were divided into three groups on the basis of the field size. SAD was changed from 80 to 130 cm and field size to determine the dose distribution to the change, each dose was measured using MatriXX Phantom. Analysis of measured values obtained from the program for each patient through the treatment planning system comparison and analysis of the dose distribution and gamma values were expressed. SAD 80, 100, and 120 cm in size in the gamma value to the investigation of patients less than 3 cm{sup 2} average 0.939, 0.969, and 0.979, respectively. Patients with more than 5 cm{sup 2} 0.962, 0.983, and 0.988, respectively. 5 cm{sup 2} or more patients 0.982, 0.990, and 0.992, respectively. The error rate of less than 3 cm{sup 2} field size is increased rapidly. If the field size is increased, resolution is increased by 2D ion chambers. It has been approved that it can be credible if it is around 3 cm{sup 2} when measuring dose distribution using MatriXX. Adjusting geometric field size by changing SAD is likely to be very useful when you measure dose distribution using MatriXX.

  5. Effective dose to patient measurements in flat-detector and multislice computed tomography: a comparison of applications in neuroradiology.

    Science.gov (United States)

    Struffert, Tobias; Hauer, Michael; Banckwitz, Rosemarie; Köhler, Christoph; Royalty, Kevin; Doerfler, Arnd

    2014-06-01

    Flat-detector CT (FD-CT) is used for a variety of applications. Additionally, 3D rotational angiography (3D DSA) is used to supplement digital subtraction angiography (DSA) studies. The aim was to measure and compare the dose of (1) standard DSA and 3D DSA and (2) analogous FD-CT and multislice CT (MSCT) protocols. Using an anthropomorphic phantom, the effective dose to patients (according to ICRP 103) was measured on an MSCT and a flat-detector angiographic system using standard protocols as recommended by the manufacturer. (1) Evaluation of DSA and 3D DSA angiography protocols: ap.-lat. Standard/low-dose series 1/0.8 mSv, enlarged oblique projection 0.3 mSv, 3D DSA 0.9 mSv (limited coverage length 0.3 mSv). (2) Comparison of FD-CT and MSCT: brain parenchyma imaging 2.9 /1.4 mSv, perfusion imaging 2.3/4.2 mSv, temporal bone 0.2 /0.2 mSv, angiography 2.9/3.3 mSv, limited to the head using collimation 0.5/0.5 mSv. The effective dose for an FD-CT application depends on the application used. Using collimation for FD-CT applications, the dose may be reduced considerably. Due to the low dose of 3D DSA, we recommend using this technique to reduce the number of DSA series needed to identify working projections. Effective dose of FD-CT in comparison to MSCT is in comparable range. Collimation decreases the dose of FD-CT effectively. Effective dose of 3-D angiography is identical to 2-D DSA. Different FD-CT programs have different dose.

  6. On-line depth measurement for laser-drilled holes based on the intensity of plasma emission

    Science.gov (United States)

    Ho, Chao-Ching; Chiu, Chih-Mu; Chang, Yuan-Jen; Hsu, Jin-Chen; Kuo, Chia-Lung

    2014-09-01

    The direct time-resolved depth measurement of blind holes is extremely difficult due to the short time interval and the limited space inside the hole. This work presents a method that involves on-line plasma emission acquisition and analysis to obtain correlations between the machining processes and the optical signal output. Given that the depths of laser-machined holes can be estimated on-line using a coaxial photodiode, this was employed in our inspection system. Our experiments were conducted in air under normal atmospheric conditions without gas assist. The intensity of radiation emitted from the vaporized material was found to correlate with the depth of the hole. The results indicate that the estimated depths of the laser-drilled holes were inversely proportional to the maximum plasma light emission measured for a given laser pulse number.

  7. Optimal matching of 3D film-measured and planned doses for intensity-modulated radiation therapy quality assurance.

    Science.gov (United States)

    Shin, Dongho; Yoon, Myonggeun; Park, Sung Yong; Park, Dong Hyun; Lee, Se Byeong; Kim, Dae Yong; Cho, Kwan Ho

    2007-01-01

    Intensity-modulated radiation therapy (IMRT) is one of the most complex applications of radiotherapy that requires patient-specific quality assurance (QA). Here, we describe a novel method of 3-dimensional (3D) dose-verification using 12 acrylic slabs in a 3D phantom (30 x 30 x 12 cm(3)) with extended dose rate (EDR2) films, which is both faster than conventionally used methods, and clinically useful. With custom-written software modules written in Microsoft Excel Visual Basic Application, the measured and planned dose distributions for the axial, coronal, and sagittal planes were superimposed by matching their origins, and the point doses were compared at all matched positions. Then, an optimization algorithm was used to correct the detected setup errors. The results show that this optimization method significantly reduces the average maximum dose difference by 7.73% and the number of points showing dose differences of more than 5% by 8.82% relative to the dose differences without an optimization. Our results indicate that the dose difference was significantly decreased with optimization and this optimization method is statistically reliable and effective. The results of 3D optimization are discussed in terms of various patient-specific QA data obtained from statistical analyses.

  8. Comparison of measured and calculated spatial dose distributions for a bench-mark 106Ru/106Rh hot particle source.

    Science.gov (United States)

    Aydarous, A Sh; Charles, M W; Darley, P J

    2008-01-01

    This study is a part of a programme of research to provide validated dose measurement and calculation techniques for beta emitting hot particles by the construction of well-defined model hot particle sources. This enables parallel measurements and calculations to be critically compared. This particular study concentrates on the high-energy beta emitter, (106)Ru/(106)Rh (Emax = 3.54 MeV). This source is a common constituent of failed nuclear fuel, particularly in accident situations. The depth dose distributions were measured using radiochromic dye film (RDF); an imaging photon detector coupled to an LiF thermoluminescent dosemeter (LiF-IPD) and an extrapolation ionisation chamber (ECH). Dose calculations were performed using the Monte Carlo radiation transport code MCNP4C. Doses were measured and calculated as average values over various areas and depths. Of particular interest are the doses at depths of 7 and 30-50 mg cm(-2), and averaged over an area of 1 cm2, as recommended by the International Commission on Radiological Protection for use in routine and accidental over-exposures of the skin. In this case, the average ratios (MCNP/measurement) for RDF, ECH and LiF-IPD were 1.07 +/- 0.02, 1.02 +/- 0.01 and 0.83 +/- 0.16, respectively. There are significantly greater discrepancies between the ECH and LiF-IPD measurement techniques and calculations-particularly for shallow depths and small averaging areas.

  9. Process Analytical Technology and On-Line Spectroscopic Measurements of Chemical Meat Quality

    DEFF Research Database (Denmark)

    Sørensen, Klavs Martin

    This thesis deals with process analytical technology and how it can be implemented in the meat industry through on-line grading of chemical meat quality. The focus will be on two applications, namely the rapid quality control of fat quality and the development of a method for on-line detection...... of boar taint. The chemical makeup of fat has a large effect on meat cut quality. Fat quality has traditionally been determined by methylation of a tissue sample followed by chromatography on a GC-MS system, elucidating the composition of the individual fatty acids. As this procedure typically takes far...... on surgical castration will be in effect starting 2018. With the ban, the risk of meat products with the malodorous taint reaching the consumer is highly increased, and thus, detection of boar taint is a necessity. No current on-line detection system is available; the only alternative is chemical extraction...

  10. Measurements of radioactivity and dose assessments in some building materials in Bitlis, Turkey.

    Science.gov (United States)

    Kayakökü, Halime; Karatepe, Şule; Doğru, Mahmut

    2016-09-01

    In this study, samples of perlite, pumice and Ahlat stones (Ignimbrite) extracted from mines in Bitlis and samples of other building materials produced in facilities in Bitlis were collected and analyzed. Activity concentrations of (226)Ra, (232)Th and (40)K in samples of building materials were measured using NaI detector (NaI(Tl)) with an efficiency of 24%. The radon measurements of building material samples were determined using CR-39 nuclear track detectors. (226)Ra, (232)Th and (40)K radioactivity concentrations ranged from (29.6±5.9 to 228.2±38.1Bq/kg), (10.8±5.4 to 95.5±26.1Bq/kg) and (249.3±124.7 to 2580.1±266.9Bq/kg), respectively. Radon concentration, radium equivalent activities, absorbed dose rate, excess lifetime cancer risk and the values of hazard indices were calculated for the measured samples to assess the radiation hazards arising from using those materials in the construction of dwellings. Radon concentration ranged between 89.2±12.0Bq/m(3) and 1141.0±225.0Bq/m(3). It was determined that Raeq values of samples conformed to world standards except for perlite and single samples of brick and Ahlat stone. Calculated values of absorbed dose rate ranged from 81.3±20.5 to 420.6±42.8nGy/h. ELCR values ranged from (1.8±0.3)×10(-3) to (9.0±1.0)×10(-3). All samples had ELCR values higher than the world average. The values of Hin and Hex varied from 0.35±0.11 to 1.78±0.18 and from 0.37±0.09 to 1.17±0.13, respectively. The results were compared with standard radioactivity values determined by international organizations and with similar studies. There would be a radiation risk for people living in buildings made of perlite, Ahlat-1 and Brick-3.

  11. Experimental Study on an On-Line Measurement of High Temperature Circulating Ash Flux in a Circulating Fluidized Bed Boiler

    Institute of Scientific and Technical Information of China (English)

    Lu Xiaofeng; Li Yourong

    2001-01-01

    A new kind of measuring method that may be used to measure high temperature circulating solid particles flux in a circulating fluidized bed boiler is studied in this paper. The measuring method is founded on the principle of thermal equilibrium. A series of cold tests and hot tests were carried to optimize the structure and collocation of water-cooling tubes and showed that the method had the advantage of simple, accurate, reliable and good applicability for on-line usage in a circulating fluidized bed boiler.

  12. A brief measure of Smokers' knowledge of lung cancer screening with low-dose computed tomography

    Directory of Open Access Journals (Sweden)

    Lisa M. Lowenstein

    2016-12-01

    Full Text Available We describe the development and psychometric properties of a new, brief measure of smokers' knowledge of lung cancer screening with low-dose computed tomography (LDCT. Content experts identified key facts smokers should know in making an informed decision about lung cancer screening. Sample questions were drafted and iteratively refined based on feedback from content experts and cognitive testing with ten smokers. The resulting 16-item knowledge measure was completed by 108 heavy smokers in Houston, Texas, recruited from 12/2014 to 09/2015. Item difficulty, item discrimination, internal consistency and test-retest reliability were assessed. Group differences based upon education levels and smoking history were explored. Several items were dropped due to ceiling effects or overlapping constructs, resulting in a 12-item knowledge measure. Additional items with high item uncertainty were retained because of their importance in informed decision making about lung cancer screening. Internal consistency reliability of the final scale was acceptable (KR-20 = 0.66 and test-retest reliability of the overall scale was 0.84 (intraclass correlation. Knowledge scores differed across education levels (F = 3.36, p = 0.04, while no differences were observed between current and former smokers (F = 1.43, p = 0.24 or among participants who met or did not meet the 30-pack-year screening eligibility criterion (F = 0.57, p = 0.45. The new measure provides a brief, valid and reliable indicator of smokers' knowledge of key concepts central to making an informed decision about lung cancer screening with LDCT, and can be part of a broader assessment of the quality of smokers' decision making about lung cancer screening.

  13. Introducing process analytical technology (PAT) in filamentous cultivation process development: comparison of advanced online sensors for biomass measurement.

    Science.gov (United States)

    Rønnest, Nanna Petersen; Stocks, Stuart M; Eliasson Lantz, Anna; Gernaey, Krist V

    2011-10-01

    The recent process analytical technology (PAT) initiative has put an increased focus on online sensors to generate process-relevant information in real time. Specifically for fermentation, however, introduction of online sensors is often far from straightforward, and online measurement of biomass is one of the best examples. The purpose of this study was therefore to compare the performance of various online biomass sensors, and secondly to demonstrate their use in early development of a filamentous cultivation process. Eight Streptomyces coelicolor fed-batch cultivations were run as part of process development in which the pH, the feeding strategy, and the medium composition were varied. The cultivations were monitored in situ using multi-wavelength fluorescence (MWF) spectroscopy, scanning dielectric (DE) spectroscopy, and turbidity measurements. In addition, we logged all of the classical cultivation data, such as the carbon dioxide evolution rate (CER) and the concentration of dissolved oxygen. Prediction models for the biomass concentrations were estimated on the basis of the individual sensors and on combinations of the sensors. The results showed that the more advanced sensors based on MWF and scanning DE spectroscopy did not offer any advantages over the simpler sensors based on dual frequency DE spectroscopy, turbidity, and CER measurements for prediction of biomass concentration. By combining CER, DE spectroscopy, and turbidity measurements, the prediction error was reduced to 1.5 g/l, corresponding to 6% of the covered biomass range. Moreover, by using multiple sensors it was possible to check the quality of the individual predictions and switch between the sensors in real time.

  14. Online Measurements of Water-Soluble Iron in Ambient Aerosols: A new Technique

    Science.gov (United States)

    Rastogi, N.; Oakes, M.; Weber, R. J.; Majestic, B. J.; Shafer, M. M.; Snyder, D. C.; Schauer, J. J.

    2008-05-01

    Water-soluble iron, i.e. Fe(II) (hereafter, WS-Fe), is a redox active metal that can act as a catalyst in the production of reactive oxygen species (ROS). In atmospheric aerosol particles, WS-Fe may significantly impact human health and the atmospheric oxidative capacity. Further, WS-Fe acts as a critical nutrient for marine organisms and has been hypothesized to limit phytoplankton productivity in high nitrate, low-chlorophyll ocean regions. In order to assess the role of aerosol WS-Fe on human health, atmospheric chemistry and ocean biogeochemistry, it is necessary to understand its major sources, transport, transformation processes and sinks. Filter-based measurements with several (6-24) hours integration time are predominately used to quantify WS-Fe in aerosols but provide limited insight into acute exposures that could be higher than daily averages, or sources having high temporal variability. Generally, mineral dust and its processing with acidic pollutants, is considered the dominant source of WS-Fe, however, recent studies have reported combustion emissions are also a possible source. A time-resolved data set may help in identifying WS-Fe sources, atmospheric transformations and possible sinks. We have developed a new system for online quantitative analyses of WS-Fe present in ambient aerosols with a 12-minute integration time. It mainly consists of Particle-Into-Liquid Sampler (PILS), a liquid waveguide capillary cell (LWCC) and a portable UV-Visible spectrophotometer. The complete system is automated so that first the liquid sample (water-extract of ambient aerosols from PILS) is mixed with ferrozine (complexing reagent) by pumping them simultaneously (10:1) through a serpentine reactor and a 100 turn mixing coil using a peristaltic pump. After holding the mixed solution in the mixing coil for three minutes, the sample is pumped through the LWCC and held there for two minutes to acquire the absorbance of the solution at 562 nm (for Fe

  15. Measuring organisational readiness for patient engagement (MORE): an international online Delphi consensus study.

    Science.gov (United States)

    Oostendorp, Linda J M; Durand, Marie-Anne; Lloyd, Amy; Elwyn, Glyn

    2015-02-14

    Widespread implementation of patient engagement by organisations and clinical teams is not a reality yet. The aim of this study is to develop a measure of organisational readiness for patient engagement designed to monitor and facilitate a healthcare organisation's willingness and ability to effectively implement patient engagement in healthcare. The development of the MORE (Measuring Organisational Readiness for patient Engagement) scale was guided by Weiner's theory of organisational readiness for change. Weiner postulates that an organisation's readiness is determined by both the willingness and ability to implement the change (i.e. in this context: patient engagement). A first version of the scale was developed based on a literature search and evaluation of pre-existing tools. We invited multi-disciplinary stakeholders to participate in a two-round online Delphi survey. Respondents were asked to rate the importance of each proposed item, and to comment on the proposed domains and items. Second round participants received feedback from the first round and were asked to re-rate the importance of the revised, new and unchanged items, and to provide comments. The first version of the scale contained 51 items divided into three domains: (1) Respondents' characteristics; (2) the organisation's willingness to implement patient engagement; and (3) the organisation's ability to implement patient engagement. 131 respondents from 16 countries (health care managers, policy makers, clinicians, patients and patient representatives, researchers, and other stakeholders) completed the first survey, and 72 of them also completed the second survey. During the Delphi process, 34 items were reworded, 8 new items were added, 5 items were removed, and 18 were combined. The scale's instructions were revised. The final version of MORE totalled 38 items; 5 on stakeholders, 13 on an organisation's willingness to implement, and 20 on an organisation's ability to implement patient

  16. Motion as a perturbation: Measurement-guided dose estimates to moving patient voxels during modulated arc deliveries

    Energy Technology Data Exchange (ETDEWEB)

    Feygelman, Vladimir; Zhang, Geoffrey; Hunt, Dylan; Opp, Daniel [Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Stambaugh, Cassandra [Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Wolf, Theresa K. [Live Oak Technologies LLC, Kirkwood, Missouri 63122 (United States); Nelms, Benjamin E. [Canis Lupus LLC, Merrimac, Wisconsin 53561 (United States)

    2013-02-15

    Purpose: To present a framework for measurement-guided VMAT dose reconstruction to moving patient voxels from a known motion kernel and the static phantom data, and to validate this perturbation-based approach with the proof-of-principle experiments. Methods: As described previously, the VMAT 3D dose to a static patient can be estimated by applying a phantom measurement-guided perturbation to the treatment planning system (TPS)-calculated dose grid. The fraction dose to any voxel in the presence of motion, assuming the motion kernel is known, can be derived in a similar fashion by applying a measurement-guided motion perturbation. The dose to the diodes in a helical phantom is recorded at 50 ms intervals and is transformed into a series of time-resolved high-density volumetric dose grids. A moving voxel is propagated through this 4D dose space and the fraction dose to that voxel in the phantom is accumulated. The ratio of this motion-perturbed, reconstructed dose to the TPS dose in the phantom serves as a perturbation factor, applied to the TPS fraction dose to the similarly situated voxel in the patient. This approach was validated by the ion chamber and film measurements on four phantoms of different shape and structure: homogeneous and inhomogeneous cylinders, a homogeneous cube, and an anthropomorphic thoracic phantom. A 2D motion stage was used to simulate the motion. The stage position was synchronized with the beam start time with the respiratory gating simulator. The motion patterns were designed such that the motion speed was in the upper range of the expected tumor motion (1-1.4 cm/s) and the range exceeded the normally observed limits (up to 5.7 cm). The conformal arc plans for X or Y motion (in the IEC 61217 coordinate system) consisted of manually created narrow (3 cm) rectangular strips moving in-phase (tracking) or phase-shifted by 90 Degree-Sign (crossing) with respect to the phantom motion. The XY motion was tested with the computer-derived VMAT

  17. Performance Evaluation of a Multichannel All-In-One Phantom Dosimeter for Dose Measurement of Diagnostic X-ray Beam

    Directory of Open Access Journals (Sweden)

    Hyesu Jeon

    2015-11-01

    Full Text Available We developed a multichannel all-in-one phantom dosimeter system composed of nine sensing probes, a chest phantom, an image intensifier, and a complementary metal-oxide semiconductor (CMOS image sensor to measure the dose distribution of an X-ray beam used in radiation diagnosis. Nine sensing probes of the phantom dosimeter were fabricated identically by connecting a plastic scintillating fiber (PSF to a plastic optical fiber (POF. To measure the planar dose distribution on a chest phantom according to exposure parameters used in clinical practice, we divided the top of the chest phantom into nine equal parts virtually and then installed the nine sensing probes at each center of the nine equal parts on the top of the chest phantom as measuring points. Each scintillation signal generated in the nine sensing probes was transmitted through the POFs and then intensified by the image intensifier because the scintillation signal normally has a very low light intensity. Real-time scintillation images (RSIs containing the intensified scintillation signals were taken by the CMOS image sensor with a single lens optical system and displayed through a software program. Under variation of the exposure parameters, we measured RSIs containing dose information using the multichannel all-in-one phantom dosimeter and compared the results with the absorbed doses obtained by using a semiconductor dosimeter (SCD. From the experimental results of this study, the light intensities of nine regions of interest (ROI in the RSI measured by the phantom dosimeter were similar to the dose distribution obtained using the SCD. In conclusion, we demonstrated that the planar dose distribution including the entrance surface dose (ESD can be easily measured by using the proposed phantom dosimeter system.

  18. Performance Evaluation of a Multichannel All-In-One Phantom Dosimeter for Dose Measurement of Diagnostic X-ray Beam.

    Science.gov (United States)

    Jeon, Hyesu; Yoo, Wook Jae; Shin, Sang Hun; Kwon, Guwon; Kim, Mingeon; Kim, Hye Jin; Song, Young Beom; Jang, Kyoung Won; Youn, Won Sik; Lee, Bongsoo

    2015-11-11

    We developed a multichannel all-in-one phantom dosimeter system composed of nine sensing probes, a chest phantom, an image intensifier, and a complementary metal-oxide semiconductor (CMOS) image sensor to measure the dose distribution of an X-ray beam used in radiation diagnosis. Nine sensing probes of the phantom dosimeter were fabricated identically by connecting a plastic scintillating fiber (PSF) to a plastic optical fiber (POF). To measure the planar dose distribution on a chest phantom according to exposure parameters used in clinical practice, we divided the top of the chest phantom into nine equal parts virtually and then installed the nine sensing probes at each center of the nine equal parts on the top of the chest phantom as measuring points. Each scintillation signal generated in the nine sensing probes was transmitted through the POFs and then intensified by the image intensifier because the scintillation signal normally has a very low light intensity. Real-time scintillation images (RSIs) containing the intensified scintillation signals were taken by the CMOS image sensor with a single lens optical system and displayed through a software program. Under variation of the exposure parameters, we measured RSIs containing dose information using the multichannel all-in-one phantom dosimeter and compared the results with the absorbed doses obtained by using a semiconductor dosimeter (SCD). From the experimental results of this study, the light intensities of nine regions of interest (ROI) in the RSI measured by the phantom dosimeter were similar to the dose distribution obtained using the SCD. In conclusion, we demonstrated that the planar dose distribution including the entrance surface dose (ESD) can be easily measured by using the proposed phantom dosimeter system.

  19. Measurements with a Ge detector and Monte Carlo computations of dose rate yields due to cosmic muons.

    Science.gov (United States)

    Clouvas, A; Xanthos, S; Antonopoulos-Domis, M; Silva, J

    2003-02-01

    The present work shows how portable Ge detectors can be useful for measurements of the dose rate due to ionizing cosmic radiation. The methodology proposed converts the cosmic radiation induced background in a Ge crystal (energy range above 3 MeV) to the absorbed dose rate due to muons, which are responsible for 75% of the cosmic radiation dose rate at sea level. The key point is to observe in the high energy range (above 20 MeV) the broad muon peak resulting from the most probable energy loss of muons in the Ge detector. An energy shift of the muon peak was observed, as expected, for increasing dimensions of three Ge crystals (10%, 20%, and 70% efficiency). Taking into account the dimensions of the three detectors the location of the three muon peaks was reproduced by Monte Carlo computations using the GEANT code. The absorbed dose rate due to muons has been measured in 50 indoor and outdoor locations at Thessaloniki, the second largest town of Greece, with a portable Ge detector and converted to the absorbed dose rate due to muons in an ICRU sphere representing the human body by using a factor derived from Monte Carlo computations. The outdoor and indoor mean muon dose rate was 25 nGy h(-1) and 17.8 nGy h(-1), respectively. The shielding factor for the 40 indoor measurements ranges from 0.5 to 0.9 with a most probable value between 0.7-0.8.

  20. Measurements of low photon doses using LiF:Mg,Cu,P and CaF{sub 2}:Cu dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Prokert, K. [Dresden Univ. of Technology (Germany). Inst. of Radiation Protection Physics; Mann, G. [Dresden Univ. of Technology (Germany). Inst. of Radiation Protection Physics

    1997-03-01

    The new thermoluminophors LiF:Mg, Cu, P and CaF{sub 2}:Cu in form of pellets exhibit a significantly higher TL-response than the well-known dosimeters of the types TLD-100 (LiF:Mg, Ti), TLD-400 (CaF{sub 2}:Mn), TLD-900 (CaSO{sub 4}:Dy), etc. Furthermore, the thermoluminophor LiF:Mg, Cu, P shows besides its high sensitivity a good tissue equivalence and therefore, only a small variation of the dose response with the photon energy. The lower limits of detection of these new materials are about 5 {mu}Gy and 0.2 {mu}Gy resp. Therefore, short term measurements of absorbed dose can be realised in radiation fields at very low dose rates (environmental radiation, scattering radiation at medical equipment`s etc.) with an accuracy of {+-}10%. In the field of environmental monitoring the period of exposure can be limited to about 10 days. Using CaF{sub 2}:Cu detectors an exposure of 24 hours is sufficient for dose measurements with lower accuracy. The reusability of CaF{sub 2}:Cu pellets is guaranteed without loss of sensitivity independently of the application of different reading and annealing procedures. In the case of LiF:Mg, Cu, P detectors special procedures are needed in order to keep constant TL-properties. The results of dose measurements at low dose levels in different radiation fields demonstrate the advantages of these detector types. (orig.)

  1. The Additive Effects of Values Clarification Training to an Online Goal-Setting Procedure on Measures of Student Retention and Performance

    Science.gov (United States)

    Chase, Jared A.

    2010-01-01

    The purpose of this study was to provide individuals with online tutorials to help participants generate strategies to achieve their academic goals and clarify their academic values to assess the additive effects of values clarification training to an online goal-setting training procedure on (1) measures of academic performance and (2) student…

  2. SU-E-T-44: Angular Dependence of Surface Dose Enhancement Measured On Several Inhomogeneities Using Radiochromic EBT3 Films

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, A; Schoenfeld, A; Poppinga, D; Chofor, N; Poppe, B [University of Oldenburg, Oldenburg (Germany); Pius Hospital Oldenburg, Oldenburg (Germany)

    2014-06-01

    Purpose: The quantification of the relative surface dose enhancement in dependence on the angle of incidence and the atomic number Z of the surface material. Methods: Experiments were performed with slabs made of aluminum, titanium, copper, silver, dental gold and lead. The metal slabs with equal sizes of 1.0×8.0×8.8mm{sup 3} were embedded in an Octavius 4D phantom (PTW Freiburg, Germany). Radiochromic EBT3 films were used to measure the surface dose for angles of incidence ranging from 0° to 90°. The setup with the metals slabs at the isocenter was irradiated with acceleration voltages of 6MV and 10MV. Water reference measurements were taken under equal conditions. Results: The surface dose enhancement is highest for angles of incidence below 30° and drops significantly for higher. The surface dose enhancement produced by lead and dental gold at 6MV showed a peak of 65%. At 90°, the surface dose enhancement dropped to 15% for both materials. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 32%, 22% and 12% at 0°, respectively. At an angle of incidence of 80°, the values dropped to 22%, 18%, 12% und 6%. The values for 10MV were very similar. Lead and dental gold showed peaks of 65% und 60%. Their values dropped to 18% at an angle of 90°. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 30%, 20% and 8% at 0°. At 80° the values dropped to 30%, 20%, 12% and 5%. A dependence of the magnitude of the surface dose enhancement on the atomic number of the surface material can be seen, which is in consistence with literature. Conclusion: The results show that the surface dose enhancements near implant materials with high Z-values should be taken into consideration in radio therapy, even when the angle of incidence is flat.

  3. Measurements of environmental radiation exposure dose rates at selected sites in Brazil.

    Science.gov (United States)

    Pfeiffer, W C; Penna-Franca, E; Ribeiro, C C; Nogueira, A R; Londres, H; Oliveira, A E

    1981-12-01

    Two types of portable instruments were developed by the former Health and Safety Laboratory of the U.S. Atomic Energy Commission to characterize external gamma radiation fields and to estimate individual exposure dose rates from major natural or fission radionuclides distributed in the soil: a pressurized ionization chamber and a NaI(T1) gamma-ray spectrometer. The two instruments were used to measure environmental radiation exposure rates at three distinct geological areas of Brazil: - in the towns of Guarapari and Meaípe located on the monazite sand belt, ES. - on the vicinities of the uranium mine of Poços de Caldas, MG. - around the site of the Brazilian first nuclear power plant, in Angra dos Reis, RJ. The radiometric survey demonstrated once more the usefulness and versatility of the two instruments used. The measurements around the nuclear installations of Poços de Caldas and Angra dos Reis, allowed a rapid assessment of the local radiation background and its variability, as well as the selection of stations for the routine monitoring program. Radioactive anomalies were detected and characterized previously to the start of plant operations. The survey in Guarapari and Meaípe confirmed the results obtained by Roser and Cullen in 1958 and 1962, except on sites where considerable changes took place since then. The spectrometric measurements gave estimations of the relative proportion of 40K, 238U and 232Th series in the ground and also indications on the homogeneity of their distribution in the soil.

  4. The Impact Factor: Measuring Student Professional Growth in an Online Doctoral Program

    Science.gov (United States)

    Kumar, Swapna; Dawson, Kara

    2014-01-01

    This article describes the impact of an online Ed.D. in educational technology based on data collected from students at regular intervals during the program. It documents how students who were working professionals applied learning from the program within their practice, enculturated into the educational technology community, and grew…

  5. Measuring Malaysia School Resource Centers' Standards through iQ-PSS: An Online Management Information System

    Science.gov (United States)

    Zainudin, Fadzliaton; Ismail, Kamarulzaman

    2010-01-01

    The Ministry of Education has come up with an innovative way to monitor the progress of 9,843 School Resource Centers (SRCs) using an online management information system called iQ-PSS (Quality Index of SRC). This paper aims to describe the data collection method and analyze the current state of SRCs in Malaysia and explain how the results can be…

  6. A New Method of Measuring Online Media Advertising Effectiveness: Prospective Meta-Analysis in Marketing

    NARCIS (Netherlands)

    G. Liberali (Gui); G.L. Urban (Glen); B.G.C. Dellaert (Benedict); C. Tucker (Catherine); Y. Bart (Yakov); S. Stremersch (Stefan)

    2016-01-01

    textabstractThe authors introduce a new method, prospective meta-analysis in marketing (PMM), to estimate consumer response to online advertising on a large and adaptive scale. They illustrate their approach in a field study in the U.S., China and the Netherlands, covering equivalent ad content on s

  7. A New Method of Measuring Online Media Advertising Effectiveness: Prospective Meta-Analysis in Marketing

    NARCIS (Netherlands)

    G. Liberali (Gui); G.L. Urban (Glen); B.G.C. Dellaert (Benedict); C. Tucker (Catherine); Y. Bart (Yakov); S. Stremersch (Stefan)

    2016-01-01

    textabstractThe authors introduce a new method, prospective meta-analysis in marketing (PMM), to estimate consumer response to online advertising on a large and adaptive scale. They illustrate their approach in a field study in the U.S., China and the Netherlands, covering equivalent ad content on s

  8. A New Method of Measuring Online Media Advertising Effectiveness: Prospective Meta-Analysis in Marketing

    NARCIS (Netherlands)

    G. Liberali (Gui); G.L. Urban (Glen); B.G.C. Dellaert (Benedict); C. Tucker (Catherine); Y. Bart (Yakov); S. Stremersch (Stefan)

    2016-01-01

    textabstractThe authors introduce a new method, prospective meta-analysis in marketing (PMM), to estimate consumer response to online advertising on a large and adaptive scale. They illustrate their approach in a field study in the U.S., China and the Netherlands, covering equivalent ad content on

  9. Online Searching: Measures That Discriminate among Users with Different Types of Experiences.

    Science.gov (United States)

    Fenichel, Carol Hansen

    1981-01-01

    Describes a study conducted to identify the differences among the searches of users of online systems who have different amounts of overall experience, and the differences between the searches of persons with and without experience on the database being searched. Twenty-five references are cited. (FM)

  10. Time-resolved SAXS measurements facilitated by online HPLC buffer exchange

    DEFF Research Database (Denmark)

    Jensen, Malene Hillerup; Toft, Katrine Nørgaard; David, Gabriel

    2010-01-01

    continuous or stopped flow. In this paper a method for obtaining TR-SAXS data from systems where the reaction is triggered by removal of a species is presented. This method is based on fast buffer exchange over a short desalting column facilitated by an online HPLC (high-performance liquid chromatography...

  11. Monitoring and control of the biogas process based on propionate concentration using online VFA measurement

    DEFF Research Database (Denmark)

    Boe, Kanokwan; Steyer, J.P.; Angelidaki, Irini

    2008-01-01

    Simple logic control algorithms were tested for automatic control of a lab-scale CSTR manure digester. Using an online VFA monitoring system, propionate concentration in the reactor was used as parameter for control of the biogas process. The propionate concentration was kept below a threshold...

  12. Design and Test of a Low-Cost RGB Sensor for Online Measurement of Microalgae Concentration within a Photo-Bioreactor

    Directory of Open Access Journals (Sweden)

    Micaela Benavides

    2015-02-01

    Full Text Available In this study, a low-cost RGB sensor is developed to measure online the microalgae concentration within a photo-bioreactor. Two commercially available devices, i.e., a spectrophotometer for offline measurements and an immersed probe for online measurements, are used for calibration and comparison purposes. Furthermore, the potential of such a sensor for estimating other variables is illustrated with the design of an extended Luenberger observer.

  13. Characteristics of Gafchromic XRQA2 films for kV image dose measurement

    Energy Technology Data Exchange (ETDEWEB)

    Giaddui, Tawfik; Cui Yunfeng; Galvin, James; Chen Wenzhou; Yu Yan; Xiao Ying [Department Of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 (United States)

    2012-02-15

    Purpose: In this study, the relevant characteristics of the new Gafchromic XRQA2 film for its application in measuring kV cone beam computed tomography (CBCT) image doses were thoroughly investigated. Methods: The film was calibrated free in air to air kerma levels between 0 and 9 cGy using 120 kVp photon beams produced by the x-ray volume imager. Films were scanned using transmission and reflection scanning modes with the Epson Expression 10000 XL flat-bed document scanner. The impact of film size, region of interest for the analysis, scan uniformity, scan resolution, scan orientation and alternate scanning sides on the analysis process were investigated. Energy dependence, postirradiation growth of reflectance with time and irradiation angular dependence of the film were tested at different air kerma levels. Results: The net reflectance changed by {approx}3% when the size of the film piece changed from 1 cm x 2 cm to 10 cm x 11 cm and changed by {approx}1% when ROI changed from 0. 7 cm x 0. 7 cm to 8 cm x 8 cm, suggesting a good uniformity of the film. The film was successfully analyzed using the transmission scanning mode, calibration curves from both transmission and reflection scanning modes showed similar behavior. The calibration uncertainty was somewhat lower when the film was scanned using reflection mode (6% and 8% for reflection and transmission modes, respectively.) Higher scanning resolution came with increasing calibration uncertainty. The calibration uncertainty for reflection and transmission modes increased from {approx}3.5% to 7% and from {approx}3.5% to 9%, respectively when scanning resolution was changed from 50 to 400 dpi. Scanning the film on alternate sides using transmission mode led to variation of 16%-19% in the net optical density at doses commonly used for CBCT procedures. The film response changed by almost 10% when it was exposed to beams of two different energies (100 and 120 kVp.) Other features of the film such as film orientation

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

    Science.gov (United States)

    Reynaldo, S R; Benavente, J A; Da Silva, T A

    2016-11-01

    Beta Secondary Standard 2 (BSS 2) provides beta radiation fields with certified values of absorbed dose to tissue and the derived operational radiation protection quantities. As part of the quality assurance, the reliability of the CDTN BSS2 system was verified through measurements in the (90)Sr/(90)Y and (85)Kr beta radiation fields. Absorbed dose rates and their angular variation were measured with a 23392 model PTW extrapolation chamber and with Gafchromic radiochromic films on a PMMA slab phantom. The feasibility of using both methods was analyzed.

  15. Silicon diodes as an alternative to diamond detectors for depth dose curves and profile measurements of photon and electron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Scherf, Christian; Moog, Jussi; Licher, Joerg; Kara, Eugen; Roedel, Claus; Ramm, Ulla [Dept. of Radiotherapy and Oncology, Center of Radiology, Univ. Hospital, Frankfurt/Main (Germany); Peter, Christiane [Dept. of Radiotherapy and Oncology, Center of Radiology, Univ. Hospital, Frankfurt/Main (Germany); Inst. for Medical Physics and Radiation Protection, Advanced Technical Coll. Giessen-Friedberg (Germany); Zink, Klemens [Inst. for Medical Physics and Radiation Protection, Advanced Technical Coll. Giessen-Friedberg (Germany)

    2009-08-15

    Background: Depth dose curves and lateral dose profiles should correspond to relative dose to water in any measured point, what can be more or less satisfied with different detectors. Diamond as detector material has similar dosimetric properties like water. Silicon diodes and ionization chambers are also commonly used to acquire dose profiles. Material and Methods: The authors compared dose profiles measured in an MP3 water phantom with a diamond detector 60003, unshielded and shielded silicon diodes 60008 and 60012 and a 0.125-cm{sup 3} thimble chamber 233642 (PTW, Freiburg, Germany) for 6- and 25-MV photons. Electron beams of 6, 12 and 18 MeV were investigated with the diamond detector, the unshielded diode and a Markus chamber 23343. Results: The unshielded diode revealed relative dose differences at the water surface below +10% for 6-MV and +4% for 25-MV photons compared to the diamond data. These values decreased to less than 1% within the first millimeters of water depth. The shielded diode was only required to obtain correct data of the fall-off zones for photon beams larger than 10 x 10 cm{sup 2} because of important contributions of low-energy scattered photons. For electron radiation the largest relative dose difference of -2% was observed with the unshielded silicon diode for 6 MeV within the build-up zone. Spatial resolutions were always best with the small voluminous silicon diodes. Conclusion: Relative dose profiles obtained with the two silicon diodes have the same degree of accuracy as with the diamond detector. (orig.)

  16. Survey and online discussion groups to develop a patient-rated outcome measure on acceptability of treatment response in vitiligo.

    Science.gov (United States)

    Tour, Selina K; Thomas, Kim S; Walker, Dawn-Marie; Leighton, Paul; Yong, Adrian Sw; Batchelor, Jonathan M

    2014-06-14

    Vitiligo is a chronic depigmenting skin disorder which affects around 0.5-1% of the world's population. The outcome measures used most commonly in trials to judge treatment success focus on repigmentation. Patient-reported outcome measures of treatment success are rarely used, although recommendations have been made for their inclusion in vitiligo trials. This study aimed to evaluate the face validity of a new patient-reported outcome measure of treatment response, for use in future trials and clinical practice. An online survey to gather initial views on what constitutes treatment success for people with vitiligo or their parents/carers, followed by online discussion groups with patients to reach consensus on what constitutes treatment success for individuals with vitiligo, and how this can be assessed in the context of trials. Participants were recruited from an existing database of vitiligo patients and through posts on the social network sites Facebook and Twitter. A total of 202 survey responses were received, of which 37 were excluded and 165 analysed. Three main themes emerged as important in assessing treatment response: a) the match between vitiligo and normal skin (how well it blends in); b) how noticeable the vitiligo is and c) a reduction in the size of the white patches. The majority of respondents said they would consider 80% or more repigmentation to be a worthwhile treatment response after 9 months of treatment. Three online discussion groups involving 12 participants led to consensus that treatment success is best measured by asking patients how noticeable their vitiligo is after treatment. This was judged to be best answered using a 5-point Likert scale, on which a score of 4 or 5 represents treatment success. This study represents the first step in developing a patient reported measure of treatment success in vitiligo trials. Further work is now needed to assess its construct validity and responsiveness to change.

  17. Application of the Nordtest method for "real-time" uncertainty estimation of on-line field measurement.

    Science.gov (United States)

    Näykki, Teemu; Virtanen, Atte; Kaukonen, Lari; Magnusson, Bertil; Väisänen, Tero; Leito, Ivo

    2015-10-01

    Field sensor measurements are becoming more common for environmental monitoring. Solutions for enhancing reliability, i.e. knowledge of the measurement uncertainty of field measurements, are urgently needed. Real-time estimations of measurement uncertainty for field measurement have not previously been published, and in this paper, a novel approach to the automated turbidity measuring system with an application for "real-time" uncertainty estimation is outlined based on the Nordtest handbook's measurement uncertainty estimation principles. The term real-time is written in quotation marks, since the calculation of the uncertainty is carried out using a set of past measurement results. There are two main requirements for the estimation of real-time measurement uncertainty of online field measurement described in this paper: (1) setting up an automated measuring system that can be (preferably remotely) controlled which measures the samples (water to be investigated as well as synthetic control samples) the way the user has programmed it and stores the results in a database, (2) setting up automated data processing (software) where the measurement uncertainty is calculated from the data produced by the automated measuring system. When control samples with a known value or concentration are measured regularly, any instrumental drift can be detected. An additional benefit is that small drift can be taken into account (in real-time) as a bias value in the measurement uncertainty calculation, and if the drift is high, the measurement results of the control samples can be used for real-time recalibration of the measuring device. The procedure described in this paper is not restricted to turbidity measurements, but it will enable measurement uncertainty estimation for any kind of automated measuring system that performs sequential measurements of routine samples and control samples/reference materials in a similar way as described in this paper.

  18. Measuring ventricular width on cranial computed tomography. Feasibility of dose reduction in a custom-made adult phantom

    Energy Technology Data Exchange (ETDEWEB)

    Daubner, D.; Cerhova, J.; Linn, J. [Dresden Univ. (Germany). Dept. of Neuroradiology; Spieth, S. [Dresden Univ. (Germany). Dept. of Radiology; Kirchhof, K. [Chemnitz Hospital (Germany). Dept. of Diagnostic and Interventional Radiology and Neuradiology

    2016-01-15

    To estimate feasible dose reduction to reliably measure ventricular width in adults with hydrocephalus in follow-up cranial computed tomography (CCT) using a custom-made phantom. A gelatine-filled adult calvarium with embedded central fibers of two carrots representing the lateral ventricles was used as a phantom. The phantom was scanned 11 times with two CT scanners (LightSpeed Ultra, GE and Somatom Sensation, Siemens), using tube currents of 380/400, 350, 300, 250, 200, 150 and 100 mA, and tube voltages of 140, 120, 100 and 80 kV. The width of the carrots was measured at four sites in consensus decision of two principle investigators blinded to the scan parameters. Values measured at 380/400 mA and 140 kV served as a reference for the width of the ventricles. Measurements received 1 point if they did not differ more than 0.5 mm from the reference values. A maximum score of 4 could be achieved. The relationship between the correct width measurement of the carrots (lateral ventricles) and the radiation dose can be described by a quadratic regression function. Pixel noise increases and accuracy of measurements decreases with a lower radiation dose. Starting from a tube current of 380/400 mA and a tube voltage of 140 kV, the dose can be reduced by 76 % for LightSpeed Ultra and by 80 % for Somatom Sensation provided that a margin of error of 37.5 % (score = 2.5) for correct width measurement of the carrots is accepted. Lowering the radiation dose by up to 48 % for LightSpeed Ultra and by 52 % for Somatom Sensation, compared to the standard protocol (120 kV and 400 mA) still allowed reliable measurements of ventricular widths in this model.

  19. A dual-frequency online PMP method with phase-shifting parallel to moving direction of measured object

    Science.gov (United States)

    Peng, Kuang; Cao, Yiping; Wu, Yingchun; Chen, Cheng; Wan, Yingying

    2017-01-01

    A dual-frequency online phase measurement profilometry (PMP) method with phase-shifting parallel to moving direction of measured object is proposed in this paper. The high-frequency fringe is used for the better modulation patterns in pixel matching and it is not modified by the measured object's surface. Based on the relative positive between the moving measured object and digital light processing (DLP), the high-frequency fringe in each dual-frequency deformed pattern after pixel matching is the same. As a result, the phase can be calculated directly by the improved Stoilov algorithm without filtering out the low-frequency component containing the measured object's height information. As there is no filtering process in phase calculation, the valid information loss can be avoided so that the accuracy of the proposed method can be guaranteed. Simulations and experiments prove the method's feasibility and precision.

  20. Translating the Science of Measuring Ecosystems at a National Scale: NEON's Online Learning Portal

    Science.gov (United States)

    Wasser, L. A.

    2015-12-01

    "Big Data" are becoming increasingly common in many fields. The National Ecological Observatory Network (NEON) will collect data over the 30 years, using consistent, standardized methods across the United States. These freely available new data provide an opportunity for increased understanding of continental- and global scale processes such as changes in vegetation structure and condition, biodiversity and landuse. However, while "big data" are becoming more accessible and available, working with big data is challenging. New and potentially unfamiliar data types and associated processing methods, required to work with a growing diversity of available data take time and resources to learn. Analysis of these big datasets may further present a challenge given large file sizes, and uncertainty regarding best methods to properly statistically summarize and analyze results. Finally, resources that support learning these concepts and approaches, are distributed widely across multiple online spaces and may take time to find. This presentation will overview the development of NEON's collaborative University-focused online education portal. It will also cover content testing, community feedback and results from workshops using online content. Portal content is hosted in github to facilitate community input, accessibility version control. Content includes 1) videos and supporting graphics that explain key concepts related to NEON and related big spatio-temporal and 2) data tutorials that include subsets of spatio-temporal data that can be used to learn key big data skills in a self-paced approach, or that can be used as a teaching tool in the classroom or in a workshop. All resources utilize free and open data processing, visualization and analysis tools, techniques and scripts. All NEON materials are being developed in collaboration with the scientific community and are being tested via in-person workshops. Visit the portal online: www.neondataskills.org.

  1. Impulsivity in Multiplayer Online Battle Arena Gamers: Preliminary Results on Experimental and Self-Report Measures.

    Science.gov (United States)

    Nuyens, Filip; Deleuze, Jory; Maurage, Pierre; Griffiths, Mark D; Kuss, Daria J; Billieux, Joël

    2016-06-01

    Background and aims Multiplayer Online Battle Arena (MOBA) games have become the most popular type of video games played worldwide, superseding the playing of Massively Multiplayer Online Role-Playing Games and First-Person Shooter games. However, empirical studies focusing on the use and abuse of MOBA games are still very limited, particularly regarding impulsivity, which is an indicator of addictive states but has not yet been explored in MOBA games. In this context, the objective of the present study is to explore the associations between impulsivity and symptoms of addictive use of MOBA games in a sample of highly involved League of Legends (LoL, currently the most popular MOBA game) gamers. Methods Thirty-six LoL gamers were recruited and completed both experimental (Single Key Impulsivity Paradigm) and self-reported impulsivity assessments (s-UPPS-P Impulsive Behavior Scale, Barratt Impulsiveness Scale), in addition to an assessment of problematic video game use (Problematic Online Gaming Questionnaire). Results Results showed links between impulsivity-related constructs and signs of excessive MOBA game involvement. Findings indicated that impaired ability to postpone rewards in an experimental laboratory task was strongly related to problematic patterns of MOBA game involvement. Although less consistent, several associations were also found between self-reported impulsivity traits and signs of excessive MOBA game involvement. Conclusions Despite these results are preliminary and based upon a small (self-selected) sample, the present study highlights potential psychological factors related to the addictive use of MOBA games.

  2. Online absolute pose compensation and steering control of industrial robot based on six degrees of freedom laser measurement

    Science.gov (United States)

    Yang, Juqing; Wang, Dayong; Fan, Baixing; Dong, Dengfeng; Zhou, Weihu

    2017-03-01

    In-situ intelligent manufacturing for large-volume equipment requires industrial robots with absolute high-accuracy positioning and orientation steering control. Conventional robots mainly employ an offline calibration technology to identify and compensate key robotic parameters. However, the dynamic and static parameters of a robot change nonlinearly. It is not possible to acquire a robot's actual parameters and control the absolute pose of the robot with a high accuracy within a large workspace by offline calibration in real-time. This study proposes a real-time online absolute pose steering control method for an industrial robot based on six degrees of freedom laser tracking measurement, which adopts comprehensive compensation and correction of differential movement variables. First, the pose steering control system and robot kinematics error model are constructed, and then the pose error compensation mechanism and algorithm are introduced in detail. By accurately achieving the position and orientation of the robot end-tool, mapping the computed Jacobian matrix of the joint variable and correcting the joint variable, the real-time online absolute pose compensation for an industrial robot is accurately implemented in simulations and experimental tests. The average positioning error is 0.048 mm and orientation accuracy is better than 0.01 deg. The results demonstrate that the proposed method is feasible, and the online absolute accuracy of a robot is sufficiently enhanced.

  3. Can we measure working memory via the Internet? The reliability and factorial validity of an online n-back task

    Directory of Open Access Journals (Sweden)

    Kulikowski Konrad

    2016-04-01

    Full Text Available The aim of this study was to check whether an online n-back task conducted in the uncontrolled environment of the Internet can yield valid and reliable data. For this purpose, 169 participants completed an online n-back task with n1, n2 and n3 blocks on their home computers. The results have shown acceptable reliability for overall accuracy and reaction time indices across n1, n2, n3 blocks, as well as for reaction time indices for each n block. Unacceptable reliability has been found for separate n levels accuracy indices and for response bias indices. Confirmatory factor analysis has revealed that, among 8 proposed measurement models, the best fit for the data collected is a model with two uncorrelated factors: accuracy consisting of n1, n2, n3 indices and reaction time consisting of n2, n3 indices. The results of this study have demonstrated for the first time that a reliable administration of online n-back task is possible and may therefore give rise to new opportunities for working memory research.

  4. Experimental determination of the lateral dose response functions of detectors to be applied in the measurement of narrow photon-beam dose profiles

    Science.gov (United States)

    Poppinga, D.; Meyners, J.; Delfs, B.; Muru, A.; Harder, D.; Poppe, B.; Looe, HK

    2015-12-01

    This study aims at the experimental determination of the detector-specific 1D lateral dose response function K(x) and of its associated rotational symmetric counterpart K(r) for a set of high-resolution detectors presently used in narrow-beam photon dosimetry. A combination of slit-beam, radiochromic film, and deconvolution techniques served to accomplish this task for four detectors with diameters of their sensitive volumes ranging from 1 to 2.2 mm. The particular aim of the experiment was to examine the existence of significant negative portions of some of these response functions predicted by a recent Monte-Carlo-simulation (Looe et al 2015 Phys. Med. Biol. 60 6585-607). In a 6 MV photon slit beam formed by the Siemens Artiste collimation system and a 0.5 mm wide slit between 10 cm thick lead blocks serving as the tertiary collimator, the true cross-beam dose profile D(x) at 3 cm depth in a large water phantom was measured with radiochromic film EBT3, and the detector-affected cross-beam signal profiles M(x) were recorded with a silicon diode, a synthetic diamond detector, a miniaturized scintillation detector, and a small ionization chamber. For each detector, the deconvolution of the convolution integral M(x)  =  K(x)  ∗  D(x) served to obtain its specific 1D lateral dose response function K(x), and K(r) was calculated from it. Fourier transformations and back transformations were performed using function approximations by weighted sums of Gaussian functions and their analytical transformation. The 1D lateral dose response functions K(x) of the four types of detectors and their associated rotational symmetric counterparts K(r) were obtained. Significant negative curve portions of K(x) and K(r) were observed in the case of the silicon diode and the diamond detector, confirming the Monte-Carlo-based prediction (Looe et al 2015 Phys. Med. Biol. 60 6585-607). They are typical for the perturbation of the secondary electron field by a detector with

  5. SU-E-I-04: A Mammography Phantom to Measure Mean Glandular Dose and Image Quality

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Pineda, E; Ruiz-Trejo, C; E, Brandan M [Instituto de Fisica UNAM, Mexico City, DF (Mexico)

    2014-06-01

    Purpose: To evaluate mean glandular dose (MGD) and image quality in a selection of mammography systems using a novel phantom based on thermoluminescent dosemeters and the ACR wax insert. Methods: The phantom consists of two acrylic, 19 cm diameter, 4.5 cm thick, semicircular modules, used in sequence. The image quality module contains the ACR insert and is used to obtain a quality control image under automatic exposure conditions. The dosimetric module carries 15 TLD-100 chips, some under Al foils, to determine air kerma and half-value-layer. TL readings take place at our laboratory under controlled conditions. Calibration was performed using an ionization chamber and a Senographe 2000D unit for a variety of beam qualities, from 24 to 40 kV, Mo and Rh anodes and filters. Phantom MGD values agree, on the average, within 3% with ionization chamber data, and their precision is better than 10% (k=1). Results: MGD and image quality have been evaluated in a selection of mammography units currently used in Mexican health services. The sample includes analogic (screen/film), flexible digital (CR), and full-field digital image receptors. The highest MDG are associated to the CR technology. The most common image quality failure is due to artifacts (dust, intensifying screen scratches, and processor marks for film/screen, laser reader defects for CR). Conclusion: The developed phantom permits the MGD measurement without the need of a calibrated ionization chamber at the mammography site and can be used by a technician without the presence of a medical physicist. The results indicate the urgent need to establish quality control programs for mammography.

  6. Online Partial Discharge Measurement of a High-voltage Direct Current Converter Wall-bushing%Online Partial Discharge Measurement of a High-voltage Direct Current Converter Wall-bushing

    Institute of Scientific and Technical Information of China (English)

    Nathan D. Jacob; William M. McDermid; Behzad Kordi

    2011-01-01

    An online partial discharge (PD) measurement performed on a high voltage direct current (HVDC) wall bushing successfully identified the presence of internal discharges. The wall bushing is a sulfur hexafluoride gas-insu- lated bushing, rated for 500 kV dc and terminated on a thyristor-controlled HVDC converter bridge. The measure- ment of PD within the HVDC station environment is particularly challenging due to the high levels of electromagnetic noise caused by thyristor switching events and external air-corona from the neighboring high-voltage equipment. An additional challenge is the "mixed" voltage stress on the bushing insulation, which has both ac and dc high-voltage components. There are also fast transients during the firing of thyristors in the HVDC conversion process that cause added stress to the insulation. As a result, the analysis and interpretation of PD data for HVDC equipment is more complex; PD pulses may occur in response to the ac, dc, or switching transient voltage stresses. In this paper, an on- line PD measurement strategy for noise filtering and isolation of PD sources within the bushing are discussed. The PD measurement data is plotted on a phase-resolved diagram where the line supply power cord voltage was used as a reference. The phase-resolved diagram appears to suggest that the fast transients, caused during switching, trigger some PD events. Measurements were also performed with the aid of a modern PD measurement instrument having noise separation capabilities. The findings from the online PD measurements are verified with physical evidence, found after the bushing was removed from service, suggested internal PD had occurred inside the bushing.

  7. A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources.

    Science.gov (United States)

    Sliski, Alan; Soares, Christopher; Mitch, Michael G

    2006-01-01

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a (103)Pd source of air-kerma strength 3.4 U (1 U = 1 microGy m(2) h(-1)), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries such as eye applicators for treating macular degeneration.

  8. Design of an on-line measuring system for 0.14 THz high-power terahertz pulse

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guangqiang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Wang Jianguo; Li Xiaoze; Tong Changjiang; Wang Xuefeng, E-mail: wgq02@mails.tsinghua.edu.cn [Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

    2011-02-01

    An on-line measuring system, including an aperture-coupling structure and a novel high-power pulse detector, is proposed in this paper to measure the output pulses from high-power 0.14THz surface wave oscillator (SWO). At first a T-type coupling structure between the TM{sub 01} mode of circular waveguide with radius of 6mm and TE{sub 10} mode of rectangular waveguide WR6 is designed. Based on loose coupling theory,the coupling degree of this structure is derived and calculated, reaching about -47dB with the aperture radius of 0.4mm and length of 0.5mm. The reasonable coincidence is found between the theoretical computation and numerical simulation employing the three-dimensional finite difference time domain method. Then a novel high-power terahertz pulse detector based on hot electron effect in semiconductors is developed for the detection of output pulses from T-type coupling structure. With hot electron theory, the working principle of the detector is elucidated, also its sensitivity is simply analyzed, showing that this detector is capable of handling the pulse power as high as 2kW. The present 0.14THz on-line measuring system would be convenient to monitor the terahertz pulse shape and pulse power during the application researches of SWO besides increasing the accuracy of its pulse power measurement.

  9. SU-E-T-282: Dose Measurements with An End-To-End Audit Phantom for Stereotactic Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R; Artschan, R [Calvary Mater Newcastle, Newcastle, NSW (Australia); Thwaites, D [University of Sydney, Sydney, NSW (Australia); Lehmann, J [Calvary Mater Newcastle, Newcastle, NSW (Australia); University of Sydney, Sydney, NSW (Australia)

    2015-06-15

    Purpose: Report on dose measurements as part of an end-to-end test for stereotactic radiotherapy, using a new audit tool, which allows audits to be performed efficiently either by an onsite team or as a postal audit. Methods: Film measurements have been performed with a new Stereotactic Cube Phantom. The phantom has been designed to perform Winston Lutz type position verification measurements and dose measurements in one setup. It comprises a plastic cube with a high density ball in its centre (used for MV imaging with film or EPID) and low density markers in the periphery (used for Cone Beam Computed Tomography, CBCT imaging). It also features strategically placed gold markers near the posterior and right surfaces, which can be used to calculate phantom rotations on MV images. Slit-like openings allow insertion of film or other detectors.The phantom was scanned and small field treatment plans were created. The fields do not traverse any inhomogeneities of the phantom on their paths to the measurement location. The phantom was setup at the delivery system using CBCT imaging. The calculated treatment fields were delivered, each with a piece of radiochromic film (EBT3) placed in the anterior film holder of the phantom. MU had been selected in planning to achieve similar exposures on all films. Calibration films were exposed in solid water for dose levels around the expected doses. Films were scanned and analysed following established procedures. Results: Setup of the cube showed excellent suitability for CBCT 3D alignment. MV imaging with EPID allowed for clear identification of all markers. Film based dose measurements showed good agreement for MLC created fields down to 0.5 mm × 0.5 mm. Conclusion: An end-to-end audit phantom for stereotactic radiotherapy has been developed and tested.

  10. Dosimetric measurements and Monte Carlo simulation for achieving uniform surface dose in pulsed electron beam irradiation facility

    Indian Academy of Sciences (India)

    V C Petwal; J N Rao; Jishnu Dwivedi; V K Senecha; K V Subbaiah

    2010-03-01

    A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile, showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping between the successive pulses of a scan to achieve ± 5% dose uniformity along the scanning direction. A mathematical model, which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is discussed and the results are compared with the experimentally measured values, which show that the agreement is better than 15%. Finally, harmonized setting