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1

MAGIC Gel Dosimetry  

NASA Astrophysics Data System (ADS)

Proton therapy has proven a very successful tool in treating certain tumors, but a three dimensional view of this fact has not yet been clearly demonstrated. In this experiment we have used MAGIC (Methacrylic and Ascorbic Acid in Gelatin Initiated by Copper) gel to represent brain tissue and gone through normal treatment planning for an Acoustic Neuroma to show the three dimensional dose distributions associated with such a tumor.

Mifflin, Rachel; Shahnazi, Kambiz; Jesseph, Rick

2008-10-01

2

TOPICAL REVIEW: Polymer gel dosimetry  

Microsoft Academic Search

Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant

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

2010-01-01

3

Review article Radiation dosimetry using polymer gels: methods and  

E-print Network

Review article Radiation dosimetry using polymer gels: methods and applications 1 M MCJURY, PhD, 1 dosimetry, including gel manufacture, imaging, calibration and application to radiotherapy veri and stereotactic radiosurgery. All the studies have con®rmed the value and versatility of the dosimetry technique

Doran, Simon J.

4

Laser microbeam CT scanning of dosimetry gels  

NASA Astrophysics Data System (ADS)

A novel design of an optical tomographic scanner is described that can be used for 3D mapping of optical attenuation coefficient within translucent cylindrical objects with spatial resolution on the order of 100 microns. Our scanner design utilizes the cylindrical geometry of the imaged object to obtain the desired paths of the scanning light rays. A rotating mirror and a photodetector are placed at two opposite foci of the translucent cylinder that acts as a cylindrical lens. A He-Ne laser beam passes first through a focusing lens and then is reflected by the rotating mirror, so as to scan the interior of the cylinder with focused and parallel paraxial rays that are subsequently collected by the photodetector to produce the projection data, as the cylinder rotates in small angle increments between projections. Filtered backprojection is then used to reconstruct planar distributions of optical attenuation coefficient in the cylinder. Multiplanar scans are used to obtain a complete 3D tomographic reconstruction. Among other applications, the scanner can be used in radiation therapy dosimetry and quality assurance for mapping 3D radiation dose distributions in various types of tissue-equivalent gel phantoms that change their optical attenuation coefficients in proportion to the absorbed radiation dose.

Maryanski, Marek J.; Ranade, Manisha K.

2001-06-01

5

PREFACE: The 5th International Conference on Radiotherapy Gel Dosimetry (DOSGEL 2008)  

Microsoft Academic Search

The International Conference on Radiotherapy Gel Dosimetry (DOSGEL) is held every two years. Its purpose is to bring together basic science and clinical researchers, medical physicists and clinicians from around the world to discuss the state-of-the-art of the gel dosimetry technique and to set the directions and trends for its future improvements. Gel dosimetry can be broadly defined as using

Thomas G. Maris; Evangelos Pappas

2009-01-01

6

Investigations in x-ray computed tomography polyacrylamide gel dosimetry  

SciTech Connect

Polyacrylamide gels (PAGs) are radiosensitive materials currently under development for use as three-dimensional (3D) dosimeters in radiation therapy. Dose information is recorded in the gels and extracted through imaging. X-ray computed tomography (CT) has emerged as a promising gel imaging method due to a change in gel density that occurs upon irradiation. The accessibility of CT technology to cancer hospitals makes CT read out clinically attractive; however, the technique remains of limited clinical use due in part to poor dose resolution. This thesis investigates the use of CT for extracting dose information from PAGs with an overall goal of improving achievable dose resolution. Thesis results are divided into three studies: a gel-compositional study, a study of noise and dose resolution, and a digital filtering study. The first study investigates the effects of gel composition on PAG CT dose response and the underlying density change. Results indicate dramatic variation in CT dose response sensitivity and range with gel composition. A model is developed to describe gel density change with dose, revealing two fundamental properties of the density to dose response: the density change per unit polymer yield is highest for gels with low and high concentrations of crosslinking molecules, and dose response sensitivity is linearly dependent on the total concentration of monomers in the gel. The second study investigates strategies for minimizing noise in CT polymer gel dosimetry and assesses system performance. Specifically, the effects of phantom design, scanning technique, and voxel size on image noise are investigated and the effect of scanning protocol on imaging time is established. The dose resolution achievable with an optimized system is then calculated, given voxel size and imaging time constraints, and compared with published values for magnetic resonance imaging (MRI) and optical CT gel dosimetry. The third study investigates the potential of image filtering for improved dose resolution in CT gel dosimetry. CT image noise is characterized and appropriate filters are tested on a CT image of a PAG irradiated with a clinically relevant dose distribution. Filter performance is found to vary dramatically, with the best filters more than halving the dose resolution without significantly distorting the spatial distribution of dose. In summary, this thesis provides insight into the fundamental nature of PAG density to dose response, develops strategies for minimizing image noise, quantifies system performance, and demonstrates that digital image filtering is an effective tool to provide additional improvements to dose resolution.

Hilts, Michelle [Physics and Astronomy, University of British Columbia, British Columbia, Canada and Medical Physics, BC Cancer Agency, Vancouver Centre, British Columbia (Canada)]. E-mail: mhilts@bccancer.bc.ca

2005-09-15

7

Radiological properties of MAGIC normoxic polymer gel dosimetry  

NASA Astrophysics Data System (ADS)

For a polymer gel dosimeter to be of use in radiation dosimetry, it should display water-equivalent radiological properties. In this study, the radiological properties of the MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) normoxic polymer gels were investigated. The mass density (?) was determined based on Archimedes' principle. The weight fraction of elemental composition and the effective atomic number (Zeff) were calculated. The electron density was also measured with 90° scattering angle at room temperature. The linear attenuation coefficient (?) of unirradiated gel, irradiated gel, and water were determined using Am-241 based on narrow beam geometry. Monte Carlo simulation was used to calculate the depth doses response of MAGIC gel and water for 6MV photon beam. The weight fractions of elements composition of MAGIC gel were close to that for water. The mass density was found to be 1027 ± 2 kg m-3, which is also very close to mass density of muscle tissue (1030 kg m-3) and 2.7% higher than that of water. The electron density (?e) and atomic number (Zeff) were found to be 3.43 × 1029 e m-3 and 7.105, respectively. The electron density measured was 2.6% greater than that for water. The atomic number was very close to that for water. The prepared MAGIC gel was found to be water equivalent based on the study of element composition, mass density, electron density and atomic number. The linear attenuation coefficient of unirradiated gel was very close to that of water. The ? of irradiated gel was found to be linear with dose 2-40 Gy. The depth dose response for MAGIC gel from a 6 MV photon beam had a percentage dose difference to water of less than 1%. Therefore it satisfies the criteria to be a good polymer gel dosimeter for radiotherapy.

Aljamal, M.; Zakaria, A.; Shamsuddin, S.

2013-04-01

8

Monte Carlo verification of gel dosimetry measurements for stereotactic radiotherapy.  

PubMed

The quality assurance of stereotactic radiotherapy and radiosurgery treatments requires the use of small-field dose measurements that can be experimentally challenging. This study used Monte Carlo simulations to establish that PAGAT dosimetry gel can be used to provide accurate, high-resolution, three-dimensional dose measurements of stereotactic radiotherapy fields. A small cylindrical container (4 cm height, 4.2 cm diameter) was filled with PAGAT gel, placed in the parietal region inside a CIRS head phantom and irradiated with a 12-field stereotactic radiotherapy plan. The resulting three-dimensional dose measurement was read out using an optical CT scanner and compared with the treatment planning prediction of the dose delivered to the gel during the treatment. A BEAMnrc/DOSXYZnrc simulation of this treatment was completed, to provide a standard against which the accuracy of the gel measurement could be gauged. The three-dimensional dose distributions obtained from Monte Carlo and from the gel measurement were found to be in better agreement with each other than with the dose distribution provided by the treatment planning system's pencil beam calculation. Both sets of data showed close agreement with the treatment planning system's dose distribution through the centre of the irradiated volume and substantial disagreement with the treatment planning system at the penumbrae. The Monte Carlo calculations and gel measurements both indicated that the treated volume was up to 3 mm narrower, with steeper penumbrae and more variable out-of-field dose, than predicted by the treatment planning system. The Monte Carlo simulations allowed the accuracy of the PAGAT gel dosimeter to be verified in this case, allowing PAGAT gel to be utilized in the measurement of dose from stereotactic and other radiotherapy treatments, with greater confidence in the future. PMID:22572565

Kairn, T; Taylor, M L; Crowe, S B; Dunn, L; Franich, R D; Kenny, J; Knight, R T; Trapp, J V

2012-06-01

9

Monte Carlo verification of gel dosimetry measurements for stereotactic radiotherapy  

NASA Astrophysics Data System (ADS)

The quality assurance of stereotactic radiotherapy and radiosurgery treatments requires the use of small-field dose measurements that can be experimentally challenging. This study used Monte Carlo simulations to establish that PAGAT dosimetry gel can be used to provide accurate, high-resolution, three-dimensional dose measurements of stereotactic radiotherapy fields. A small cylindrical container (4 cm height, 4.2 cm diameter) was filled with PAGAT gel, placed in the parietal region inside a CIRS head phantom and irradiated with a 12-field stereotactic radiotherapy plan. The resulting three-dimensional dose measurement was read out using an optical CT scanner and compared with the treatment planning prediction of the dose delivered to the gel during the treatment. A BEAMnrc/DOSXYZnrc simulation of this treatment was completed, to provide a standard against which the accuracy of the gel measurement could be gauged. The three-dimensional dose distributions obtained from Monte Carlo and from the gel measurement were found to be in better agreement with each other than with the dose distribution provided by the treatment planning system's pencil beam calculation. Both sets of data showed close agreement with the treatment planning system's dose distribution through the centre of the irradiated volume and substantial disagreement with the treatment planning system at the penumbrae. The Monte Carlo calculations and gel measurements both indicated that the treated volume was up to 3 mm narrower, with steeper penumbrae and more variable out-of-field dose, than predicted by the treatment planning system. The Monte Carlo simulations allowed the accuracy of the PAGAT gel dosimeter to be verified in this case, allowing PAGAT gel to be utilized in the measurement of dose from stereotactic and other radiotherapy treatments, with greater confidence in the future. Experimental aspects of this work were originally presented at the Engineering and Physical Sciences in Medicine Conference (EPSM-ABEC), Melbourne, 2010.

Kairn, T.; Taylor, M. L.; Crowe, S. B.; Dunn, L.; Franich, R. D.; Kenny, J.; Knight, R. T.; Trapp, J. V.

2012-06-01

10

Isotropic three-dimensional MRI-Fricke-infused gel dosimetry  

SciTech Connect

Purpose: Fricke-infused gel has been shown to be a simple and attainable method for the conformal measurement of absorbed radiation dose. Nevertheless, its accuracy is seriously hindered by the irreversible ferric ion diffusion during magnetic resonance imaging, particularly when three-dimensional (3D) dose measurement in radiosurgery is considered. In this study, the authors developed a fast three-dimensional spin-echo based Fricke gel dosimetry technique to reduce the adverse effects of ferric ion diffusion and to obtain an accurate isotropic 3D dose measurement. Methods: A skull shaped phantom containing Fricke-infused gel was irradiated using Leksell Gamma Knife. The rapid image-based dosimetry technique was applied with the use of a 3D fast spin-echo magnetic resonance imaging sequence. The authors mathematically derived and experimentally validated the correlations between dose-response characteristics and parameters of the 3D fast spin-echo MR imaging sequence. Absorbed dose profiles were assessed and compared to the calculated profiles given by the Gamma Knife treatment planning system. Coefficient of variance (CV%) and coefficient of determination (R{sup 2}) were used to evaluate the precision of dose-response curve estimation. The agreement between the measured and the planned 3D dose distributions was quantified by gamma-index analysis of two acceptance criteria. Results: Proper magnetic resonance imaging parameters were explored to render an accurate three-dimensional absorbed dose mapping with a 1 mm{sup 3} isotropic image resolution. The efficacy of the dose-response estimation was approved by an R{sup 2} > 0.99 and an average CV% of 1.6%. Average gamma pass-rate between the experimentally measured and GammaPlan calculated dose distributions were 83.8% and 99.7% for 2%/2 and 3%/3 mm criteria, respectively. Conclusions: With the designed MR imaging sequence and parameters, total 3D MR acquisition time was confined to within 20 min postirradiation, during which time ferric ion diffusion effects were negligible, thus enabling an accurate 3D radiation dose measurement.

Cho, Nai-Yu; Chu, Woei-Chyn [Institute of Biomedical Engineering, National Yang-Ming University, Taipei 11221, Taiwan (China); Huang, Sung-Cheng [Department of Molecular and Medical Pharmacology, UCLA David Geffen School of Medicine, Los Angeles, California 90095 (United States); Chung, Wen-Yuh [Neurological Institute, Taipei Veterans General Hospital, Taipei 11217, Taiwan (China); Guo, Wan-Yuo [Department of Radiology, Taipei Veterans General Hospital, Taipei 11217, Taiwan (China)

2013-05-15

11

Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry  

PubMed Central

This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM)-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low's gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery). When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low's gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a) from the same gel batch and (b) from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration. PMID:21430853

Olding, Timothy; Holmes, Oliver; DeJean, Paul; McAuley, Kim B.; Nkongchu, Ken; Santyr, Giles; Schreiner, L. John

2011-01-01

12

Monte Carlo verification of polymer gel dosimetry applied to radionuclide therapy: a phantom study.  

PubMed

This study evaluates the dosimetric performance of the polymer gel dosimeter 'Methacrylic and Ascorbic acid in Gelatin, initiated by Copper' and its suitability for quality assurance and analysis of I-131-targeted radionuclide therapy dosimetry. Four batches of gel were manufactured in-house and sets of calibration vials and phantoms were created containing different concentrations of I-131-doped gel. Multiple dose measurements were made up to 700 h post preparation and compared to equivalent Monte Carlo simulations. In addition to uniformly filled phantoms the cross-dose distribution from a hot insert to a surrounding phantom was measured. In this example comparisons were made with both Monte Carlo and a clinical scintigraphic dosimetry method. Dose-response curves generated from the calibration data followed a sigmoid function. The gels appeared to be stable over many weeks of internal irradiation with a delay in gel response observed at 29 h post preparation. This was attributed to chemical inhibitors and slow reaction rates of long-chain radical species. For this reason, phantom measurements were only made after 190 h of irradiation. For uniformly filled phantoms of I-131 the accuracy of dose measurements agreed to within 10% when compared to Monte Carlo simulations. A radial cross-dose distribution measured using the gel dosimeter compared well to that calculated with Monte Carlo. Small inhomogeneities were observed in the dosimeter attributed to non-uniform mixing of monomer during preparation. However, they were not detrimental to this study where the quantitative accuracy and spatial resolution of polymer gel dosimetry were far superior to that calculated using scintigraphy. The difference between Monte Carlo and gel measurements was of the order of a few cGy, whilst with the scintigraphic method differences of up to 8 Gy were observed. A manipulation technique is also presented which allows 3D scintigraphic dosimetry measurements to be compared to polymer gel dosimetry measurements without generating misleading errors due to the limited spatial resolution. PMID:22037790

Gear, J I; Charles-Edwards, E; Partridge, M; Flux, G D

2011-11-21

13

The application of polymer gel dosimeters to dosimetry for targeted radionuclide therapy  

NASA Astrophysics Data System (ADS)

There is a lack of standardized methodology to perform dose calculations for targeted radionuclide therapy and at present no method exists to objectively evaluate the various approaches employed. The aim of the work described here was to investigate the practicality and accuracy of calibrating polymer gel dosimeters such that dose measurements resulting from complex activity distributions can be verified. Twelve vials of the polymer gel dosimeter, 'MAGIC', were uniformly mixed with varying concentrations of P-32 such that absorbed doses ranged from 0 to 30 Gy after a period of 360 h before being imaged on a magnetic resonance scanner. In addition, nine vials were prepared and irradiated using an external 6 MV x-ray beam. Magnetic resonance transverse relaxation time, T2, maps were obtained using a multi-echo spin echo sequence and converted to R2 maps (where T2 = 1/R2). Absorbed doses for P-32 irradiated gel were calculated according to the medical internal radiation dose schema using EGSnrc Monte Carlo simulations. Here the energy deposited in cylinders representing the irradiated vials was scored. A relationship between dose and R2 was determined. Effects from oxygen contamination were present in the internally irradiated vials. An increase in O2 sensitivity over those gels irradiated externally was thought to be a result of the longer irradiation period. However, below the region of contamination dose response appeared homogenous. Due do a drop-off of dose at the periphery of the internally irradiated vials, magnetic resonance ringing artefacts were observed. The ringing did not greatly affect the accuracy of calibration, which was comparable for both methods. The largest errors in calculated dose originated from the initial activity measurements, and were approximately 10%. Measured R2 values ranged from 5-35 s-1 with an average standard deviation of 1%. A clear relationship between R2 and dose was observed, with up to 40% increased sensitivity for internally irradiated gels. Curve fits to the calibration data followed a single exponential function. The correlation coefficients for internally and externally irradiated gels were 0.991 and 0.985, respectively. With the ability to accurately calibrate internally dosed polymer gels, this technology shows promise as a means to evaluate dosimetry methods, particularly in cases of non-uniform uptake of a radionuclide.

Gear, J. I.; Flux, G. D.; Charles-Edwards, E.; Partridge, M.; Cook, G.; Ott, R. J.

2006-07-01

14

Gamma Knife relative dosimetry using VIP polymer gel and EBT radiochromic films  

Microsoft Academic Search

The VIP polymer gel-MRI method and EBT Gafchromic films were employed to obtain relative dosimetry results for the Gamma Knife (GK) radiation fields of 4 mm and 18 mm nominal diameter. Results are compared to the corresponding calculations of GammaPlan Treatment Planning System (TPS) in the form of 1D profiles and 2D distributions. Measured and planned relative dosimetry datasets are

A. Moutsatsos; L. Petrokokkinos; K. Zourari; P. Papagiannis; P. Karaiskos; K. Dardoufas; J. Damilakis; I. Seimenis; E. Georgiou

2009-01-01

15

Gamma Knife relative dosimetry using VIP polymer gel and EBT radiochromic films  

NASA Astrophysics Data System (ADS)

The VIP polymer gel-MRI method and EBT Gafchromic films were employed to obtain relative dosimetry results for the Gamma Knife (GK) radiation fields of 4 mm and 18 mm nominal diameter. Results are compared to the corresponding calculations of GammaPlan Treatment Planning System (TPS) in the form of 1D profiles and 2D distributions. Measured and planned relative dosimetry datasets are found in close agreement within experimental uncertainties. A corresponding agreement is shown for Dose Volume Histogram (DVH) results that are available only through the application of the polymer gel method.

Moutsatsos, A.; Petrokokkinos, L.; Zourari, K.; Papagiannis, P.; Karaiskos, P.; Dardoufas, K.; Damilakis, J.; Seimenis, I.; Georgiou, E.

2009-05-01

16

Optical computed tomography of radiochromic gels for accurate three-dimensional dosimetry  

NASA Astrophysics Data System (ADS)

In this thesis, three-dimensional (3-D) radiochromic Ferrous Xylenol-orange (FX) and Leuco Crystal Violet (LCV) micelles gels were imaged by laser and cone-beam (Vista(TM)) optical computed tomography (CT) scanners. The objective was to develop optical CT of radiochromic gels for accurate 3-D dosimetry of intensity-modulated radiation therapy (IMRT) and small field techniques used in modern radiotherapy. First, the cause of a threshold dose response in FX gel dosimeters when scanned with a yellow light source was determined. This effect stems from a spectral sensitivity to multiple chemical complexes that are at different dose levels between ferric ions and xylenol-orange. To negate the threshold dose, an initial concentration of ferric ions is needed in order to shift the chemical equilibrium so that additional dose results in a linear production of a coloured complex that preferentially absorbs at longer wavelengths. Second, a low diffusion leuco-based radiochromic gel consisting of Triton X-100 micelles was developed. The diffusion coefficient of the LCV micelle gel was found to be minimal (0.036 + 0.001 mm2 hr-1 ). Although a dosimetric characterization revealed a reduced sensitivity to radiation, this was offset by a lower auto-oxidation rate and base optical density, higher melting point and no spectral sensitivity. Third, the Radiological Physics Centre (RPC) head-and-neck IMRT protocol was extended to 3-D dose verification using laser and cone-beam (Vista(TM)) optical CT scans of FX gels. Both optical systems yielded comparable measured dose distributions in high-dose regions and low gradients. The FX gel dosimetry results were crossed checked against independent thermoluminescent dosimeter and GAFChromicRTM EBT film measurements made by the RPC. It was shown that optical CT scanned FX gels can be used for accurate IMRT dose verification in 3-D. Finally, corrections for FX gel diffusion and scattered stray light in the Vista(TM) scanner were developed to enable accurate acquisition of small beam dosimetric parameters for treatment planning commissioning. By applying these corrections, optically CT scanned FX and LCV gel dose measurements were found to be in agreement with reference GAFChromicRTM EBT film measurements. In conclusion, once specific problems affecting radiochromic gel materials and optical CT scanners are well understood and resolved, accurate 3-D dosimetry can be achieved. Ultimately, this will facilitate the safe clinical implementation of novel radiation treatments of cancer. Keywords. three-dimensional dosimetry, ferrous xylenol-orange gels, leuco crystal violet micelle gels, optical computed tomography, laser scanner, Vista(TM) cone-beam scanner, intensity-modulated radiation therapy, small field dosimetry.

Babic, Steven

17

Review of quantitative MRI principles for gel dosimetry  

Microsoft Academic Search

The radiation dose distribution absorbed by polymer gel dosimeters can be read out by several methods such as magnetic resonance imaging (MRI), optical CT, X-ray CT and ultrasound. MRI was the first method that was explored to read out polymer gel dosimeters. Although MRI was soon recognised as a promising technique, limited access to MRI scanners and the often (wrongly

Yves DeDeene

2009-01-01

18

In-phantom dosimetry for BNCT with Fricke and normoxic-polymer gels  

NASA Astrophysics Data System (ADS)

Measurements of in-phantom dose distributions and images are important for Boron Neutron Capture Therapy treatment planning. The method for spatial determination of absorbed doses in thermal or epithermal neutron fields, based on Fricke-xylenol-orange-infused gel dosimeters in form of layers, has revealed to be very reliable, as gel layer dosimeters give the possibility of obtaining spatial dose distributions and measurements of each dose contribution in neutron fields, by means of a properly studied procedure. Quite recently, BNCT has been applied to treat liver metastases; in this work the results of in-phantom dosimetry for explanted liver in BNCT treatments are described. Moreover, polyacrylamide gel (PAG) dosimeters in which a polymerization process appears as a consequence of absorbed dose, have been recently tested, because of their characteristic absence of diffusion. In fact, due to the diffusion of ferric ions, Fricke-gel dosimeters require prompt analysis after exposure to avoid spatial information loss. In this work the preliminary results of a study about the reliability of polymer gel in BNCT dosimetry are also discussed. Gel layers have been irradiated in a phantom exposed in the thermal column of the TRIGA MARK II reactor (Pavia). The results obtained with the two kinds of gel dosimeter have been compared.

Gambarini, G.; Agosteo, S.; Carrara, M.; Gay, S.; Mariani, M.; Pirola, L.; Vanossi, E.

2006-05-01

19

Evaluation of the potential for diacetylenes as reporter molecules in 3D micelle gel dosimetry  

NASA Astrophysics Data System (ADS)

Radiochromic micelle gel dosimeters are promising for three-dimensional (3D) radiation dosimetry because they can be read out by optical CT techniques and they have superior spatial stability compared to polymer and Fricke gel dosimeters. This study evaluates the use of diacetylenes as reporter molecules in micelle gel dosimeters. Several gels containing pentacosa-10,12-diynoic acid (PCDA) emulsified using sodium dodecyl sulfate (SDS) changed from colourless to blue upon irradiation. Unfortunately, all phantoms that experienced a colour change were turbid and would be unsuitable for 3D dosimetry. Two techniques (use of organic solvent and aqueous-phase additives) were successful in increasing colloidal stability to prevent the turbidity problem, but none of the resulting transparent gels changed colour in response to radiation. Transparent PCDA emulsions were prepared using NaOH solutions with no SDS or other emulsifier, but these transparent emulsions also did not change colour. Only turbid gels and emulsions with precipitated particles responded to radiation. These results indicate that the colour change was due to the oligomerization within precipitated PCDA crystals, and that liquid-phase emulsified PCDA did not undergo oligomerization. As a result, PCDA is not suitable for use in micelle gel dosimeters, and other radiochromic reporter molecules will need to be identified.

Nasr, A. T.; Olding, T.; Schreiner, L. J.; McAuley, K. B.

2013-02-01

20

Development and Characterization of NMR Measurements for Polymer Gel Dosimetry  

NASA Astrophysics Data System (ADS)

Polymer gel dosimeters are systems of water, gelatin, and monomers which form polymers upon irradiation. The gelatin matrix retains dose distribution in 3D form, facilitating truly integrated measurements of complex dose plans for radiation therapy. Polymer gels have two proton pools coupled by exchange: free solvent protons and bound polymerized macromolecular protons. Measuring magnetization transfer (MT) and relaxation affords useful insights into particle rigidity and chemical exchange effects on relaxation in polymer gels. Polymer gel dose response has been previously quantified with several techniques, most often in terms of MRI parameters, usually at field strengths of 1.5 T and below. The research described here investigates the dose response of a revised MAGIC gel dosimeter via both high-field imaging and simpler nuclear magnetic resonance (NMR) spectroscopy. This includes both transverse and longitudinal relaxation rates (R2 and R1) and quantitative MT parameters. We investigated estimating polymer molecular weight for a given applied dose using the Rouse model and R2 data from the imaging study. Finally, we began development of NMR methods for studying dose response, requiring adaption of NMR experiments to accommodate for radiation damping.

Kwong, Zachary; Whitney, Heather

2012-03-01

21

Gamma Knife 3-D dose distribution near the area of tissue inhomogeneities by normoxic gel dosimetry  

Microsoft Academic Search

The accuracy of the Leksell GammaPlan registered , the dose planning system of the Gamma Knife Model-B, was evaluated near tissue inhomogeneities, using the gel dosimetry method. The lack of electronic equilibrium around the small-diameter gamma beams can cause dose calculation errors in the neighborhood of an air-tissue interface. An experiment was designed to investigate the effects of inhomogeneity near

Fatih Isbakan; Yekta Ülgen; Hatice Bilge; Zeynep Ozen; Onur Agus; Bora Buyuksarac

2007-01-01

22

Optimization of MAGIC gel formulation for three-dimensional radiation therapy dosimetry  

PubMed Central

Polymer gel dosimetry aims to provide three-dimensional images of radiation therapy dose distributions in irradiated aqueous gels. The first gels required manufacture in an oxygen-free environment, but later the MAGIC formulation was introduced, which could be made in normal atmospheric conditions. Here we report our studies of the effects of variations in the composition of the MAGIC gel performed in order to optimize its performance over the useful dose range of 0 to 20 Gy. A new formulation (termed ‘MAGIC-2’) is comprised of 87% water, 4% methacrylic acid, 9% gelatin, 17.38 × 10?6 M Cu2+ and a molar ratio of ascorbic acid to [Cu2+] of 1000:1. MAGIC-2 has a dose–response slope-to-intercept ratio that is 78% greater than the original formulation and other more favorable properties. PMID:17473340

Luci, J J; Whitney, H M; Gore, J C

2013-01-01

23

Polymer gel dosimetry for synchrotron stereotactic radiotherapy and iodine dose-enhancement measurements.  

PubMed

Synchrotron stereotactic radiotherapy (SSR) is a radiotherapy technique that makes use of the interactions of monochromatic low energy x-rays with high atomic number (Z) elements. An important dose-enhancement can be obtained if the target volume has been loaded with a sufficient amount of a high-Z element, such as iodine. In this study, we compare experimental dose measurements, obtained with normoxic polymer gel (nPAG), with Monte Carlo computations. Gels were irradiated within an anthropomorphic head phantom and were read out by magnetic resonance imaging. The dose-enhancement due to the presence of iodine in the gel (iodine concentration: 5 and 10 mg ml(-1)) was measured at two radiation energies (35 and 80 keV) and was compared to the calculated factors. nPAG dosimetry was shown to be efficient for measuring the sharp dose gradients produced by SSR. The agreement between 3D gel dosimetry and calculated dose distributions was found to be within 4% of the dose difference criterion and a distance to agreement of 2.1 mm for 80% of the voxels. Polymer gel doped with iodine exhibited higher sensitivity, in good agreement with the calculated iodine-dose enhancement. We demonstrate in this preliminary study that iodine-doped nPAG could be used for measuring in situ dose distributions for iodine-enhanced SSR treatment. PMID:17671341

Boudou, C; Troprès, I; Rousseau, J; Lamalle, L; Adam, J F; Estève, F; Elleaume, H

2007-08-21

24

Dose resolution in gel dosimetry: effect of uncertainty in the calibration function.  

PubMed

Dose resolution, DdeltaP, is becoming a common method for characterizing the performance of a gel dosimeter. In this note we examine how the goodness of fit of the calibration function affects DdeltaP and show that its inclusion in the calculation of DdeltaP is essential to avoid overestimating the performance of the gel. PMID:15214548

Trapp, J V; Michael, G; Evans, P M; Baldock, C; Leach, M O; Webb, S

2004-05-21

25

Dosimetry aspects of a non-diffusing genipin-gelatin gel  

NASA Astrophysics Data System (ADS)

Genipin-gelatin gel shows promise as a stable, three-dimensional dosimeter for use in quality assurance for radiotherapy treatments. Genipin creates cross-links in gelatin, forming a blue colour that bleaches quantitatively upon irradiation. A formulation suitable for dosimetry was investigated by varying the concentrations of genipin, gelatin and sulphuric acid and determining the dose sensitivity. An important parameter of the gel preparation that affects dose sensitivity is the temperature at which the cross-linking reaction takes place. The most suitable formulation for dose measurements in 1 cm pathlength cuvettes was found to be made from 50 ?M genipin, 4% w/w gelatin and 100 mM sulphuric acid in the final gel. An evaluation of the diffusion coefficient of chromophores in this gel dosimeter demonstrated that this genipin-gelatin gel is a non-diffusing dosimeter. This dosimeter was also evaluated for stability, dose sensitivity, irradiation and measurement temperature dependence and dose rate dependence. No appreciable dependence on dose rate in the range 0.4-40 Gy min-1 was found. No appreciable dependence on measurement temperature between 15 and 23 °C was found. A slight dependence on irradiation temperature was found and this was used to determine the product of the molar linear absorption coefficient and the radiation chemical yield. Finally, the dosimeter measurement uncertainty was evaluated and this was used to determine the dose resolution. Although the focus of this work is on a genipin-gelatin gel dosimeter, the measurement and calibration techniques presented may be applied to any gel dosimetry system measured spectrophotometrically.

Davies, J. B.; Bosi, S. G.; Baldock, C.

2013-02-01

26

Gamma Knife 3-D dose distribution near the area of tissue inhomogeneities by normoxic gel dosimetry.  

PubMed

The accuracy of the Leksell GammaPlan, the dose planning system of the Gamma Knife Model-B, was evaluated near tissue inhomogeneities, using the gel dosimetry method. The lack of electronic equilibrium around the small-diameter gamma beams can cause dose calculation errors in the neighborhood of an air-tissue interface. An experiment was designed to investigate the effects of inhomogeneity near the paranosal sinuses cavities. The homogeneous phantom was a spherical glass balloon of 16 cm diameter, filled with MAGIC gel; i.e., the normoxic polymer gel. Two hollow PVC balls of 2 cm radius, filled with N2 gas, represented the air cavities inside the inhomogeneous phantom. For dose calibration purposes, 100 ml gel-containing vials were irradiated at predefined doses, and then scanned in a MR unit. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. Dose distributions are the results of a single shot of irradiation, obtained by collimating all 201 cobalt sources to a known target in the phantom. Both phantoms were irradiated at the same dose level at the same coordinates. Stereotactic frames and fiducial markers were attached to the phantoms prior to MR scanning. The dose distribution predicted by the Gamma Knife planning system was compared with that of the gel dosimetry. As expected, for the homogeneous phantom the isodose diameters measured by the gel dosimetry and the GammaPlan differed by 5% at most. However, with the inhomogeneous phantom, the dose maps in the axial, coronal and sagittal planes were spatially different. The diameters of the 50% isodose curves differed 43% in the X axis and 32% in the Y axis for the Z =90 mm axial plane; by 44% in the X axis and 24% in the Z axis for the Y=90 mm coronal plane; and by 32% in the Z axis and 42% in the Y axis for the X=92 mm sagittal plane. The lack of ability of the GammaPlan to predict the rapid dose fall off, due to the air cavities behind or near the lesion led to an overestimation of the dose that was actually delivered. Clinically, this can result in underdosing of lesions near tissue inhomogeneities in patients under treatment. PMID:17555244

Isbakan, Fatih; Ulgen, Yekta; Bilge, Hatice; Ozen, Zeynep; Agus, Onur; Buyuksarac, Bora

2007-05-01

27

Gamma Knife 3-D dose distribution near the area of tissue inhomogeneities by normoxic gel dosimetry  

SciTech Connect

The accuracy of the Leksell GammaPlan registered , the dose planning system of the Gamma Knife Model-B, was evaluated near tissue inhomogeneities, using the gel dosimetry method. The lack of electronic equilibrium around the small-diameter gamma beams can cause dose calculation errors in the neighborhood of an air-tissue interface. An experiment was designed to investigate the effects of inhomogeneity near the paranosal sinuses cavities. The homogeneous phantom was a spherical glass balloon of 16 cm diameter, filled with MAGIC gel; i.e., the normoxic polymer gel. Two hollow PVC balls of 2 cm radius, filled with N{sub 2} gas, represented the air cavities inside the inhomogeneous phantom. For dose calibration purposes, 100 ml gel-containing vials were irradiated at predefined doses, and then scanned in a MR unit. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. Dose distributions are the results of a single shot of irradiation, obtained by collimating all 201 cobalt sources to a known target in the phantom. Both phantoms were irradiated at the same dose level at the same coordinates. Stereotactic frames and fiducial markers were attached to the phantoms prior to MR scanning. The dose distribution predicted by the Gamma Knife planning system was compared with that of the gel dosimetry. As expected, for the homogeneous phantom the isodose diameters measured by the gel dosimetry and the GammaPlan registered differed by 5% at most. However, with the inhomogeneous phantom, the dose maps in the axial, coronal and sagittal planes were spatially different. The diameters of the 50% isodose curves differed 43% in the X axis and 32% in the Y axis for the Z=90 mm axial plane; by 44% in the X axis and 24% in the Z axis for the Y=90 mm coronal plane; and by 32% in the Z axis and 42% in the Y axis for the X=92 mm sagittal plane. The lack of ability of the GammaPlan registered to predict the rapid dose fall off, due to the air cavities behind or near the lesion led to an overestimation of the dose that was actually delivered. Clinically, this can result in underdosing of lesions near tissue inhomogeneities in patients under treatment.

Isbakan, Fatih; Uelgen, Yekta; Bilge, Hatice; Ozen, Zeynep; Agus, Onur; Buyuksarac, Bora [Institute of Biomedical Engineering, Bogazici University, Istanbul (Turkey); Institute of Radiation Oncology, Istanbul University, Istanbul (Turkey); Radiation Oncology Department, Marmara University Hospital, Istanbul (Turkey); Institute of Biomedical Engineering, Bogazici University, Istanbul (Turkey)

2007-05-15

28

Improved MAGIC gel for higher sensitivity and elemental tissue equivalent 3D dosimetry  

SciTech Connect

Purpose: Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O/C ratio) is very desirable to ensure realistic time-activity measurements. Methods: Glucose and urea was added to the original MAGIC formulation to adjust the O/C ratio. The dose responses of the new formulations were tested with MRI transverse relaxation rate (R2) measurements. Results: The new ingredients improved not only the elemental composition but also the sensitivity of the MAGIC gel. The O/C ratios of our new gels agree with that of soft tissue within 1%. The slopes of dose response curves were 1.6-2.7 times larger with glucose. The melting point also increased by 5 deg. C. Further addition of urea resulted in a similar slope but with an increased intercept and a decreased melting point. Conclusions: Our improved MAGIC gel formulations have higher sensitivity and better elemental tissue equivalency for 3D dosimetry applications involving nuclear reactions.

Zhu Xuping; Reese, Timothy G.; Crowley, Elizabeth M.; El Fakhri, Georges [Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114 (United States); Department of Radiology, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, 149 Thirteenth Street, Charlestown, Massachusetts 02129 (United States); Department of Radiation Oncology, Massachusetts General Hospital, 100 Blossom Street, Boston, Massachusetts 02114 (United States); Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114 (United States)

2010-01-15

29

Improved MAGIC gel for higher sensitivity and elemental tissue equivalent 3D dosimetry  

PubMed Central

Purpose: Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O?C ratio) is very desirable to ensure realistic time-activity measurements. Methods: Glucose and urea was added to the original MAGIC formulation to adjust the O?C ratio. The dose responses of the new formulations were tested with MRI transverse relaxation rate (R2) measurements. Results: The new ingredients improved not only the elemental composition but also the sensitivity of the MAGIC gel. The O?C ratios of our new gels agree with that of soft tissue within 1%. The slopes of dose response curves were 1.6–2.7 times larger with glucose. The melting point also increased by 5 °C. Further addition of urea resulted in a similar slope but with an increased intercept and a decreased melting point. Conclusions: Our improved MAGIC gel formulations have higher sensitivity and better elemental tissue equivalency for 3D dosimetry applications involving nuclear reactions. PMID:20175480

Zhu, Xuping; Reese, Timothy G.; Crowley, Elizabeth M.; El Fakhri, Georges

2010-01-01

30

Focusing optics of a parallel beam CCD optical tomography apparatus for 3D radiation gel dosimetry.  

PubMed

Optical tomography of gel dosimeters is a promising and cost-effective avenue for quality control of radiotherapy treatments such as intensity-modulated radiotherapy (IMRT). Systems based on a laser coupled to a photodiode have so far shown the best results within the context of optical scanning of radiosensitive gels, but are very slow ( approximately 9 min per slice) and poorly suited to measurements that require many slices. Here, we describe a fast, three-dimensional (3D) optical computed tomography (optical-CT) apparatus, based on a broad, collimated beam, obtained from a high power LED and detected by a charged coupled detector (CCD). The main advantages of such a system are (i) an acquisition speed approximately two orders of magnitude higher than a laser-based system when 3D data are required, and (ii) a greater simplicity of design. This paper advances our previous work by introducing a new design of focusing optics, which take information from a suitably positioned focal plane and project an image onto the CCD. An analysis of the ray optics is presented, which explains the roles of telecentricity, focusing, acceptance angle and depth-of-field (DOF) in the formation of projections. A discussion of the approximation involved in measuring the line integrals required for filtered backprojection reconstruction is given. Experimental results demonstrate (i) the effect on projections of changing the position of the focal plane of the apparatus, (ii) how to measure the acceptance angle of the optics, and (iii) the ability of the new scanner to image both absorbing and scattering gel phantoms. The quality of reconstructed images is very promising and suggests that the new apparatus may be useful in a clinical setting for fast and accurate 3D dosimetry. PMID:16585845

Krstaji?, Nikola; Doran, Simon J

2006-04-21

31

Best fit refractive index of matching liquid for 3D NIPAM gel dosimeters using optical CT  

NASA Astrophysics Data System (ADS)

The accuracy of an optical computed tomography (CT)-based dosimeter is significantly affected by the refractive index (RI) of the matching liquid. Mismatched RI induces reflection and refraction as the laser beam passes through the gel phantom. Moreover, the unwanted light rays collected by the photodetector produce image artifacts after image reconstruction from the collected data. To obtain the best image quality, this study investigates the best-fit RI of the matching liquid for a 3D NIPAM gel dosimeter. The three recipes of NIPAM polymer gel used in this study consisted of 5% gelatin, 5% NIPAM and 3% N,N'-methylene bisacrylamide, which were combined with three compositions (5, 10, and 20 mM) of Tetrakis (hydroxymethyl) phosphonium chloride. Results were evaluated using a quantitative evaluation method of the gamma evaluation technique. Results showed that the best-fit RI for the non-irradiated NIPAM gel ranges from 1.340 to 1.346 for various NIPAM recipes with sensitivities ranging from 0.0113 to 0.0227. The greatest pass rate of 88.00% is achieved using best-fit RI=1.346 of the matching liquid. The adoption of mismatching RI decreases the gamma pass rate by 2.63% to 16.75% for all three recipes of NIPAM gel dosimeters. In addition, the maximum average deviation is less than 0.1% for the red and transparent matching liquids. Thus, the color of the matching liquid does not affect the measurement accuracy of the NIPAM gel dosimeter, as measured by optical CT.

Chen, Chin-Hsing; Wu, Jay; Hsieh, Bor-Tsung; Chen, De-Shiou; Wang, Tzu-Hwei; Chien, Sou-Hsin; Chang, Yuan-Jen

2014-11-01

32

Polyvinyl alcohol-Fricke hydrogel and cryogel: two new gel dosimetry systems with low Fe3+ diffusion  

NASA Astrophysics Data System (ADS)

Two new Fricke dosimeter gel systems with low diffusion rates have been developed for 3D radiation dosimetry purposes. Both systems consist of a solution of 20% (by weight) polyvinyl alcohol (PVA) in a 50 mM H2 SO4 solution with 0.4 mM ferrous ammonium sulphate and xylenol orange (FX). The difference in the two gels is the way that the gelation process was initiated: either by bringing the temperature to (a) +5 °C or (b) -20 °C before returning them to room temperature. These gels are termed `hydrogel' and `cryogel', respectively. The hydrogel is optically transparent, and can be used with either optical or MRI detection methods for dosimetric imaging. The cryogel is rubbery in texture but opaque, so its internal Fe3+ concentration can only be measured with MRI. The hydrogel's optical attenuation coefficient is linear (r 2 = 0.99) with dose from 0 to 20 Gy with a sensitivity of 0.106 cm-1 Gy-1 (at 543 nm). In terms of MR relaxation rate, the dose response for both the hydrogel and cryogel was linear (r 2 = 0.99) with a sensitivity of 0.020 s-1 Gy-1 (at 1.5 T). The Fe3+ diffusion coefficient (at 20 °C) was measured to be 0.14 mm2 h-1 , which is significantly lower than similar preparations reported for porcine gelatin or agarose. The PVA-FX gels can be stored for long periods of time before exposure to radiation, since the auto-oxidation rate was 10 times less than that of gelatin-Fricke recipes. The new gels developed in this work are a significant improvement on previous Fricke gel systems.

Chu, K. C.; Jordan, K. J.; Battista, J. J.; Van Dyk, J.; Rutt, B. K.

2000-04-01

33

Preliminary dosimetry investigation of Tc-99m diagnostic radionuclide by NIPAM gel dosimeter  

NASA Astrophysics Data System (ADS)

The N-isopropylacrylamide (NIPAM) gel dosimeter was investigated as a suitable material for measuring absorbed doses from radionuclide sources. In this study, NIPAM gel dosimeter was used to evaluate the dose distributions of the Tc-99m radionuclide in NIPAM gel. The accumulated radioactivity range of the Tc-99m NIPAM gel is from approximately 0 MBq to 13.6 MBq (about 0.37 mCi). The NIPAM gel dosimeter with high stability and high-dose linear and non-energy dependent properties can provide various radiopharmaceutical activity intensities in the conduct of dose assessment in nuclear medicine, thereby producing the most promising dose verification tools.

Huang, You-Ruei; Chang, Yuan-Jen; Hsieh, Ling-Ling; Yu, Bi-Wei; Chu, Chien-Hau; Hsieh, Bor-Tsung

2013-06-01

34

Dosimetry study of diagnostic X-ray using doped iodide normoxic polymer gels  

NASA Astrophysics Data System (ADS)

In radiotherapy, polymer gel dosimeters are used for three-dimensional (3D) dose distribution. However, the doses are within the Gy range. In this study, we attempted to develop a low-dose 3D dosimeter within the mGy range for diagnostic radiology. The effect of the iodinated compound was used as a dose enhancement sensitizer to enhance the dose sensitivity of normoxic polymer gel dosimeters. This study aims to use N-isopropylacrylamide(NIPAM)-based and methacrylic acid (MAGAT)-based gels to evaluate the potential dose enhancement sensitizer, as well as to compare two gels that may be suitable for measuring diagnostic radiation doses. The suitable formulation of NIPAM gel [5% (w/w) gelatin, 5% (w/w) NIPAM, 3% (w/w) N,N?-methylenebisacrylamide (BIS), 5 mM tetrakis (hydroxymethyl) phosphonium chloride (THPC), and 87% (w/w) deionized distilled water] and MAGAT gel (4% MAA, 9% gelatin, 87% deionized water, and 10 mM THPC) were used and loaded with clinical iodinated contrast medium agent (Iobitridol, Xenetix® 350). Irradiation was conducted using X-ray computed tomography. The irradiation doses ranged from 0 mGy to 80 mGy. Optical computed tomography was the employed gel measurement system. The results indicate that the iodinated contrast agent yields a quantifiable dose enhancement ratio. The dose enhancement ratios of NIPAM and MAGAT gels are 3.35±0.6 and 1.36±0.3, respectively. The developed NIPAM gel in this study could be suitable for measuring diagnostic radiation doses.

Huang, Y. R.; Chang, Y. J.; Hsieh, L. L.; Liu, M. H.; Liu, J. S.; Chu, C. H.; Hsieh, B. T.

2014-11-01

35

A spatial resolution study of a new optical tomography-based polymer gel dosimetry system.  

PubMed

A spatial resolution investigation of the OCTOPUSTM-IQ scanner in combination with the new BANG3-Pro2(r) polymer gel was performed by scanning a high-contrast needle phantom. The phantom contained five thin needles (0.3_mm diameter) embedded in gel positioned in different patterns: needles were inserted (a) at 45° angle from the center of the gel container, and (b) vertically along the gel axis. The non-irradiated needle phantoms were scanned at various slice spacings (0.25-1.0_mm) and for two different laser beam orientations. Optical density profiles and their full width at half maximum (FWHM) were evaluated for resolution limit. The modulation transfer function (MTF) corresponding to measured point spread function (PSF) data was calculated. With high resolution scanning mode and 0.25_mm pixel resolution, the measured PSFs at the center of the gel dosimeter have a FWHM of 0.95_mm. The MTF for the 0.25_mm reconstruction pixel size suggests that the resolution of the system is 0.5_mm or less. We also observed a progressive degradation of the vertical needle images with off-axis distance, attributable to the defocusing of the laser beam. No significant degradation was observed up to the maximum useful reconstructed image radius of 50_mm from the gel dosimeter center axis. PMID:22066599

Sriprisan, S I; Lopatiuk-Tirpak, O; Meeks, S L; Zeidan, O A

2011-12-01

36

MRI-based polymer gel dosimetry for validating plans with multiple matrices in Gamma Knife stereotactic radiosurgery.  

PubMed

One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: TR = 7 s, echo step = 13.6 ms, field-of-view = 256 mm × 256 mm, and pixel size = 1 mm × 1 mm. Interleaved acquisition mode was used to obtain 15 to 45 2-mm-thick slices. Using a calibration relationship between absorbed dose and the spin-spin relaxation rate (R2), we converted R2 images to dose images. MATLAB-based in-house programs were used for R2 estimation and dose comparison. Gamma-index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets. PMID:21587176

Gopishankar, N; Watanabe, Yoichi; Subbiah, Vivekanandhan

2011-01-01

37

Evaluation of dose delivery accuracy of Gamma Knife by polymer gel dosimetry.  

PubMed

The BANG polymer gel dosimeter was used to evaluate 3D absorbed dose distributions in tissue delivered with Gamma Knife stereotactic radiosurgery systems. We compared dose distributions calculated with Leksell GammaPlan (LGP) treatment-planning software with dose distributions measured with the polymer gel dosimeter for single-shot irradiations. Head-sized spherical glass vessels filled with the polymer gel were irradiated with Gamma Knife. The phantoms were scanned with a 1.0T MRI scanner. The Hahn spin-echo sequence with two echoes was used for the MRI scans. Calibration relations between the spin-spin relaxation rate and the absorbed dose were obtained by using small cylindrical vials, which were filled with the polymer gel from the same batch as for the spherical phantom. We made voxel-by-voxel comparisons of measured and calculated dose distributions for 31 x 31 x 31 dose matrix elements. With the 3D dose data we calculated the tumor control probability (TCP) and normal tissue complication probability (NTCP) for a simple model. For the maximum dose of 100 Gy, the mean and one standard deviation of differences between the measured and the calculated doses were the following: -0.38+/-4.63 Gy, 1.49+/-2.77 Gy, and -1.03+/-4.18 Gy for 8-mm, 14-mm, and 18-mm collimators, respectively. Tumor control probability values for measurements were smaller than the calculations by 0% to 7%, whereas NTCP values were larger by 7% to 24% for four of six experiments. PMID:16143798

Watanabe, Yoichi; Akimitsu, Tomohide; Hirokawa, Yutaka; Mooij, Rob B; Perera, G Mark

2005-01-01

38

Indigenously developed multipurpose acrylic head phantom for verification of IMRT using film and gel dosimetry.  

PubMed

The purpose of this study was to validate the newly designed acrylic phantom for routine dosimetric purpose in radiotherapy. The phantom can be used to evaluate and compare the calculated dose and measured dose using film and gel dosimetric methods. In this study, a doughnut-shaped planning target volume (8.54 cm3) and inner organ at risk (0.353 cm3) were delineated for an IMRT test plan using the X-ray CT image of the phantom. The phantom consists of acrylic slabs which are integrated to form a human head with a hole in the middle where several dosimetric inserts can be positioned for measurement. An inverse planning with nine coplanar intensity-modulated fields was created using Pinnacle TPS. For the film analysis, EBT2 film, flatbed scanner, in-house developed MATLAB codes and ImageJ software were used. The 3D dose distribution recorded in the MAGAT gel dosimeter was read using a 1.5 T MRI scanner. Scanning parameters were CPMG pulse sequence with 8 equidistant echoes, TR = 5600, echo step = 22 ms, pixel size = 0.5 × 0.5, slice thickness = 2 mm. Using a calibration relationship between absorbed dose and spin-spin relaxation rate (R2), R2 images were converted to dose images. The dose comparison was accomplished using in-house MATLAB-based graphical user interface named "IMRT3DCMP". For gel measurement dose grid from the TPS was extracted and compared with the measured dose grid of the gel. Gamma index analysis of film measurement for the tolerance criteria of 2%/2mm, 1%/1 mm showed more than 90% voxels pass rate. Gamma index analysis of 3D gel measurement data showed more than 90% voxels pass rate for different tolerance criteria of 2%/2 mm and 1%/1 mm. Overall both 2D and 3D measurement were in close agreement with the Pinnacle TPS calculated dose. The phantom designed is cost-effective and the results are promising, but further investigation is required to validate the phantom with other 3D conformal techniques for dosimetric purpose. PMID:23470932

Gopishankar, N; Vivekanandhan, S; Rath, G K; Laviraj, M A; Senthilkumaran, S; Kale, S S; Thulkar, S; Bisht, R K; Subramani, V

2013-01-01

39

Mycosis Fungoides electron beam absorbed dose distribution using Fricke xylenol gel dosimetry  

NASA Astrophysics Data System (ADS)

Radiotherapy uses ionizing radiation to destroy tumor cells. The absorbed dose control in the target volume is realized through radiation sensors, such as Fricke dosimeters and radiochromic film, which permit to realize bi-dimensional evaluations at once and because of that, they will be used in this study as well. Among the several types of cancer suitable for ionizing radiation treatment, the Mycosis Fungoides, a lymphoma that spreads on the skin surface and depth, requires for its treatment total body irradiation by high-energy electrons. In this work the Fricke xylenol gel (FXG) was used in order to obtain information about the absorbed dose distribution induced by the electron interactions with the irradiated tissues and to control this type of treatment. FXG can be considered as an alternative dosimeter, since up to now only films have been used. FXG sample cuvettes, simulating two selected tomos (cranium and abdomen) of the Rando anthropomorphic phantom, were positioned along with radiochromic films for comparison. The phantom was subjected to Stanford total body irradiation using 6 MeV electrons. Tomographic images were acquired for both dosimeters and evaluated through horizontal and vertical profiles along the tomographic centers. These profiles were obtained through a Matlab routine developed for this purpose. From the obtained results, one could infer that, for a superficial and internal patient irradiation, the FXG dosimeter showed an absorbed dose distribution similar to the one of the film. These results can validate the FXG dosimeter as an alternative dosimeter for the Mycosis Fungoides treatment planning.

da Silveira, Michely C.; Sampaio, Francisco G. A.; Petchevist, Paulo C. D.; de Oliveira, André L.; Almeida, Adelaide de

2011-12-01

40

Cone-beam optical computed tomography for gel dosimetry II: imaging protocols  

NASA Astrophysics Data System (ADS)

This work develops imaging protocols for improved dose readout of a Fricke-xylenol orange-gelatin (FXG) gel-filled 1 L polyethylene terephthalate (PETE) jar dosimeter using a commercial VistaTM cone-beam optical computed tomography (CT) scanner from Modus Medical Devices Inc. (London, ON, Canada). To ensure good management of light source-detector stability, it was determined that (a) a minimum of 2 h warm-up time is necessary prior to dosimeter scanning, (b) the light source should be kept on until the completion of the last data scan except for the minimum amount of time required to acquire dark field images, and (c) the optional Vista software projection image normalization routine should be used in image reconstruction. The institution of dosimeter scan time and temperature control was strongly indicated from the experiments. A standard post-irradiation wait time of 30 min measured to within ±30 s was established to minimize the measurement uncertainties due to dosimeter development and diffusion. To alleviate thermochromic behavior leading to inaccurate dose readout, holding bath warm up and pre-scan temperature adjustment procedures were developed to control dosimeter temperature to within ±0.2 °C. The possibility of stray light minimizing protocols was also investigated and deemed to be unnecessary. The largest significant sources of stray light in the system were identified as being due to angled scatter from the dosimeter gelatin matrix and refraction from the jar wall interfaces. It was concluded that these phenomena would be better addressed through dosimeter modification and an inter-jar dose-to-attenuation calibration methodology, rather than by setting additional imaging protocols.

Olding, Tim; Schreiner, L. John

2011-03-01

41

Spatial Dosimetry with Violet Diode Laser-Induced Fluorescence of Water-Equivalent Radio-Fluorogenic Gels.  

E-print Network

??The following work describes investigations of spatial dosimetry using laser-induced fluorescence of a radio-fluorogenic detector embedded within water-equivalent media. The chemical composition of a gelatin-based… (more)

Sandwall, Peter A, II

2014-01-01

42

MAGAT gel and EBT2 film-based dosimetry for evaluating source plugging-based treatment plan in Gamma Knife stereotactic radiosurgery.  

PubMed

This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging. The polymer gel contained in a head-sized glass container simulated all major aspects of the treatment process of Gamma Knife radiosurgery. The 3D dose distribution recorded in the gel dosimeter was read using a 1.5T MRI scanner. Scanning protocol was: CPMG pulse sequence with 8 equidistant echoes, TR = 7 s, echo step = 14 ms, pixel size = 0.5mm × 0.5mm, and slice thickness of 2 mm. Using a calibration relationship between absorbed dose and spin-spin relaxation rate (R2), we converted R2 images to dose images. Volumetric dose comparison between treatment planning system (TPS) and gel measurement was accomplished using an in-house MATLAB-based program. The isodose overlay of the measured and computed dose distribution on axial planes was in close agreement. Gamma index analysis of 3D data showed more than 94% voxel pass rate for different tolerance criteria of 3%/2 mm, 3%/1 mm and 2%/2 mm. Film dosimetry with GAFCHROMIC EBT 2 film was also performed to compare the results with the calculated TPS dose. Gamma index analysis of film measurement for the same tolerance criteria used for gel measurement evaluation showed more than 95% voxel pass rate. Verification of gamma plan calculated dose on account of shield is not part of acceptance testing of Leksell Gamma Knife (LGK). Through this study we accomplished a volumetric comparison of dose distributions measured with a polymer gel dosimeter and Leksell GammaPlan (LGP) calculations for plans using plugging. We propose gel dosimeter as a quality assurance (QA) tool for verification of plug-based planning. PMID:23149780

Natanasabapathi, Gopishankar; Subbiah, Vivekanandhan; Kale, Shashank Sharad; Rath, Goura Kishor; Senthilkumaran, S; Thulkar, Sanjay; Subramani, Vellaiyan; Laviraj, M A; Bisht, Raj Kishor; Mahapatra, A K

2012-01-01

43

Spatial Dosimetry with Violet Diode Laser-Induced Fluorescence of Water-Equivalent Radio-Fluorogenic Gels  

NASA Astrophysics Data System (ADS)

The following work describes investigations of spatial dosimetry using laser-induced fluorescence of a radio-fluorogenic detector embedded within water-equivalent media. The chemical composition of a gelatin-based coumarin-3-carboxylic acid detector was investigated and dose response characterized. Violet diode (405nm) excitation sources were explored and laser-induced fluorescence (LIF) employed to obtain the pattern of fluorescent emission yielding images of the integrated spatial dose distribution. The design of a three-dimensional reader is proposed to provide a foundation for future work. Radio-fluorogenic processes create fluorescent products in response to ionizing radiation. Water radiolysis produced by ionizing radiation yields hydroxyl free radicals that readily hydroxylate coumarin-3-carboxylic acid to 7-hydroxy-coumarin-3-carboxylic acid, a derivative of umbelliferone. Umbelliferone is a known fluorophore, exhibiting peak excitation in the UV to near UV range of 365-405nm with a visible 445nm blue emission. Coumarin-3-carboxlyic acid has been studied in an aqueous gelatin matrix. The radio-fluorogenic coumarin-gelatin detector has been shown to respond to an absorbed dose of ionizing radiation in a measureable manner. The detector was studied with respect to concentration of gelatin and coumarin in the presence of pH buffers. Dose response of the detector was investigated with regard to ionizing radiation type, energy, and rate of irradiation. Results demonstrate a functional detector. Patterns of energy deposition were formed in response to ionizing radiation produced by a sealed-source of radioactive Ir-192 embedded in the gelatin matrix of the detector. Spatial distributions of absorbed dose were recorded and analyzed as a function of fluorescent emission. The distribution of energy deposition was imaged with LIF excitation by a divergent beam of 405nm light and determined by analysis of digital image pixel intensity values displaying the 445nm fluorescent emission. Results demonstrate spatial dosimetry proof of principle. A basic dedicated reader system was fabricated employing LIF. Images of fluorescent emission excitation profiles were obtained in multiple aqueous samples and processed to obtain a dose response. Design of an optical reader system for the radio-fluorogenic detector is explained and a three-dimensional dosimetry system proposed. Three-dimensional imaging principles with LIF have been illuminated.

Sandwall, Peter A., II

44

Fundamentals of gel dosimeters  

NASA Astrophysics Data System (ADS)

Fundamental chemical and physical phenomena that occur in Fricke gel dosimeters, polymer gel dosimeters, micelle gel dosimeters and genipin gel dosimeters are discussed. Fricke gel dosimeters are effective even though their radiation sensitivity depends on oxygen concentration. Oxygen contamination can cause severe problems in polymer gel dosimeters, even when THPC is used. Oxygen leakage must be prevented between manufacturing and irradiation of polymer gels, and internal calibration methods should be used so that contamination problems can be detected. Micelle gel dosimeters are promising due to their favourable diffusion properties. The introduction of micelles to gel dosimetry may open up new areas of dosimetry research wherein a range of water-insoluble radiochromic materials can be explored as reporter molecules.

McAuley, K. B.; Nasr, A. T.

2013-06-01

45

Gel dosimetry in the BNCT facility for extra-corporeal treatment of liver cancer at the HFR Petten.  

PubMed

A thorough evaluation of the dose inside a specially designed and built facility for extra-corporeal treatment of liver cancer by boron neutron capture therapy (BNCT) at the High Flux Reactor (HFR) Petten (The Netherlands) is the necessary step before animal studies can start. The absorbed doses are measured by means of gel dosemeters, which help to validate the Monte Carlo simulations of the spheroidal liver holder that will contain the human liver for irradiation with an epithermal neutron beam. These dosemeters allow imaging of the dose due to gammas and to the charged particles produced by the (10)B reaction. The thermal neutron flux is extrapolated from the boron dose images and compared to that obtained by the calculations. As an additional reference, Au, Cu and Mn foil measurements are performed. All results appear consistent with the calculations and confirm that the BNCT liver facility is able to provide an almost homogeneous thermal neutron distribution in the liver, which is a requirement for a successful treatment of liver metastases. PMID:17496302

Gambarini, G; Daquino, G G; Moss, R L; Carrara, M; Nievaart, V A; Vanossi, E

2007-01-01

46

An experimental investigation into the effect of periodic motion on proton dosimetry using polymer gel dosimeters and a programmable motion platform  

NASA Astrophysics Data System (ADS)

Organ motion in proton therapy affects treatment dose distribution during both double-scattering (DS) and uniform-scanning (US) deliveries. We investigated the dosimetric impact of target motion using three-dimensional polymer gel dosimeters and a programmable motion platform. A simple one-beam treatment plan with 16 cm range and 6 cm modulation was generated from the treatment planning system (TPS) in both the DS and US modes. One gel dosimeter was irradiated with a stationary DS beam. Two other gel dosimeters were irradiated with the DS and US beams while they moved in the same sinusoidal motion profile using a programmable motion platform. The dose distribution of the stationary DS delivery agreed with the TPS plan. Dosimetric comparisons between DS motion delivery and the MATLAB-based motion model showed insignificant differences. Dose-volume histograms of a cylindrical target volume inside the gel dosimeters showed target coverage degradation caused by motion. A three-dimensional gamma index calculation (3% and 3 mm) confirmed different dosimetric impacts from DS and US with the same target motion. This polymer-gel-dosimeter-based study confirmed the dosimetric impact of intrafraction target motion and its interplay with temporal delivery of different energy layers in US proton treatments.

Su, Zhong; Lopatiuk-Tirpak, Olena; Zeidan, Omar; Sruprisan, S. I.; Meeks, Sanford L.; Slopsema, Roelf; Flampouri, Stella; Li, Zuofeng

2012-02-01

47

Computational dosimetry  

SciTech Connect

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

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

1996-01-01

48

Differential dose volume histograms of Gamma Knife in the presence of inhomogeneities using MRI-polymer gel dosimetry and MC simulation  

SciTech Connect

Polymer gel dosimeters offer a practical solution to 3D dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. In this study, EGSnrc calculated and PAGAT polymer gel dosimeter measured dose volume histograms (DVHs) for single-shot irradiations of the Gamma Knife (GK) unit were used to investigate the effects of the presence of inhomogeneities on 3D dose distribution. The head phantom was a custom-built 16 cm diameter Plexiglas sphere. Inside the phantom, there is a cubic cutout for inserting the gel vials and another cutout for inserting the inhomogeneities. Following irradiation with the GK unit, the polymer gel phantoms were scanned with a 1.5 T MRI scanner. Comparing the results of measurement in homogeneous and heterogeneous phantoms revealed that inserting inhomogeneities inside the homogeneous phantom did not cause considerable disturbances on dose distribution in irradiation with 8 mm collimator within low isodose levels (<50%), which is essential for the dose sparing of sensitive structures. The results of simulation for homogeneous and inhomogeneous phantoms in irradiation with 18 mm collimator of the GK unit showed 23.24% difference in DVH within 90%-100% relative isodose level and also revealed that a significant part of the target (28.56%) received relative doses higher than the maximum dose, which exceeds the acceptance criterion (5%). Based on these results it is concluded that the presence of inhomogeneities inside the phantom can cause considerable errors in dose calculation within high isodose levels with respect to LGP prediction which assumes that the target is a homogeneous material. Moreover, it is demonstrated that the applied MC code is an accurate and stand-alone tool for 3D evaluation of dose distribution in irradiation with the GK unit, which can provide important, 3D plan evaluation criteria used in clinical practice.

Allahverdi Pourfallah, Tayyeb; Allahverdi, Mahmoud; Riahi Alam, Nader; Ay, Mohammad-Reza; Zahmatkesh, Mohammad-Hasan [Department of Biochemistry and Biophysics, Faculty of Medicine, Mazandaran University of Medical Sciences, 48175-1665 Sari (Iran, Islamic Republic of) and Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, 14155-7661 Tehran (Iran, Islamic Republic of); Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, 14155-7661 Tehran (Iran, Islamic Republic of); Novin Medical Radiation Center, 14665-599 Tehran (Iran, Islamic Republic of)

2009-07-15

49

Dosimetry of 60Co and 192Ir gamma-irradiated agarose gels by proton relaxation time measurement and NMR imaging, in a 0-100 Gy dose range.  

PubMed

Localized irradiation of the skin and subcutaneous tissues with large single doses of gamma rays can induce immediate effects characterized by erythema, desquamation, and necrosis. Correlations between the evolution of the lesions and dosimetry studies have to be established by biophysical methods. NMR studies of the effects of an irradiated Fricke solution might be a means of controlling the delivered irradiation doses. After exposition to ionizing radiations, ferrous ions are transformed into ferric ions. Both are paramagnetic ions, and proton spin-lattice relaxation is accelerated depending on the oxidation reaction. In this study, solution of ammonium ferrous sulfate in an acid environment was incorporated into a gelling substance made with agarose, so that T1 weighted image contrast could be used to detect ferric ion formation. Experiments with 192Ir and 60Co gamma rays with doses in the 0 to 100 Gy range were conducted with Fe2+ concentrations of 0.5, 1, 1.5, and 2 mM in a gelling substance containing 4% agarose. A relationship was established between the amount of Fe3+ created and the spin-lattice proton relaxation rate, which led to a straightforward dose-effect relation. The use of such high doses allowed us to reproduce realistic conditions of accidental overexposure. A linear relationship was obtained between the doses absorbed and the NMR parameters measured (T1 and relative image intensity). PMID:9106711

Chalansonnet, A; Bonnat, J L; Tricaud, Y; Lefaix, J L; Briguet, A

1997-05-01

50

Epid Dosimetry  

SciTech Connect

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

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

2011-05-05

51

Absolute calibration of polymer gel dosimeters using scintillating fibers  

NASA Astrophysics Data System (ADS)

Accurate dose distributions are still difficult to obtain using polymer gel dosimetry. While the causes for observed discrepancies are being tracked and understood in details, solutions remain elusive. Causes for discrepancies in absolute dose distributions obtained by polymer gel dosimetry include imaging artefacts and errors associated with the calibration procedure. In this preliminary study, we wanted to verify whether scintillation fiber detectors could be used to improve the accuracy of dose distributions determined by polymer gel dosimeters.

Archambault, Louis; Leclerc, Ghyslain; Beaulieu, Luc; Lepage, Martin

2006-12-01

52

(Biological dosimetry)  

SciTech Connect

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

Preston, R.J.

1990-12-17

53

Neutron personnel dosimetry  

SciTech Connect

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

Griffith, R.V.

1981-06-16

54

Screening Fit Summary of Fit  

E-print Network

Screening Fit price Summary of Fit RSquare RSquare Adj Root Mean Square Error Mean of Response condition price 2 #12;Response: price Summary of Fit RSquare RSquare Adj Root Mean Square Error Mean Linear Fit Linear Fit price = 16.0081 + 1.9001 size Summary of Fit RSquare RSquare Adj Root Mean Square

Vardeman, Stephen B.

55

Dosimetry of space radiations  

NASA Technical Reports Server (NTRS)

Harmful effects of space radiation are discussed. Radiation dosimetry methods are given. Dosimetry monitoring is investigated. Methods for measuring space radiation by ionization, thermoluminescence, and nuclear photographic emulsions are described.

Arkhangelskiy, V. V.; Markelov, V. V.; Skvortsov, S. S.; Smirennyy, L. N.; Turkin, V. N.; Chernykh, I. V.

1973-01-01

56

Software for 3D radiotherapy dosimetry. Validation  

NASA Astrophysics Data System (ADS)

The subject of this work is polyGeVero® software (GeVero Co., Poland), which has been developed to fill the requirements of fast calculations of 3D dosimetry data with the emphasis on polymer gel dosimetry for radiotherapy. This software comprises four workspaces that have been prepared for: (i) calculating calibration curves and calibration equations, (ii) storing the calibration characteristics of the 3D dosimeters, (iii) calculating 3D dose distributions in irradiated 3D dosimeters, and (iv) comparing 3D dose distributions obtained from measurements with the aid of 3D dosimeters and calculated with the aid of treatment planning systems (TPSs). The main features and functions of the software are described in this work. Moreover, the core algorithms were validated and the results are presented. The validation was performed using the data of the new PABIGnx polymer gel dosimeter. The polyGeVero® software simplifies and greatly accelerates the calculations of raw 3D dosimetry data. It is an effective tool for fast verification of TPS-generated plans for tumor irradiation when combined with a 3D dosimeter. Consequently, the software may facilitate calculations by the 3D dosimetry community. In this work, the calibration characteristics of the PABIGnx obtained through four calibration methods: multi vial, cross beam, depth dose, and brachytherapy, are discussed as well.

Kozicki, Marek; Maras, Piotr; Karwowski, Andrzej C.

2014-08-01

57

CONFORMANCE IMPROVEMENT USING GELS  

SciTech Connect

This report describes work performed during the third and final year of the project, ''Conformance Improvement Using Gels.'' Corefloods revealed throughput dependencies of permeability reduction by polymers and gels that were much more prolonged during oil flow than water flow. This behavior was explained using simple mobility ratio arguments. A model was developed that quantitatively fits the results and predicts ''clean up'' times for oil productivity when production wells are returned to service after application of a polymer or gel treatment. X-ray computed microtomography studies of gels in strongly water-wet Berea sandstone and strongly oil-wet porous polyethylene suggested that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than gel-ripping or gel-displacement mechanisms. In contrast, analysis of data from the University of Kansas suggests that the gel-ripping or displacement mechanisms are more important in more permeable, strongly water-wet sandpacks. These findings help to explain why aqueous gels can reduce permeability to water more than to oil under different conditions. Since cement is the most commonly used material for water shutoff, we considered when gels are preferred over cements. Our analysis and experimental results indicated that cement cannot be expected to completely fill (top to bottom) a vertical fracture of any width, except near the wellbore. For vertical fractures with apertures less than 4 mm, the cement slurry will simply not penetrate very far into the fracture. For vertical fractures with apertures greater than 4 mm, the slurry may penetrate a substantial distance into the bottom part of the fracture. However, except near the wellbore, the upper part of the fracture will remain open due to gravity segregation. We compared various approaches to plugging fractures using gels, including (1) varying polymer content, (2) varying placement (extrusion) rate, (3) using partially formed gels, (4) using combinations of high and low molecular weight (Mw) polymers, (5) using secondary crosslinking reactions, (6) injecting un-hydrated polymer particles, and (7) incorporating particulates. All of these methods showed promise in some aspects, but required performance improvements in other aspects. All materials investigated to date showed significant performance variations with fracture width. High pressure gradients and limited distance of penetration are common problems in tight fractures. Gravity segregation and low resistance to breaching are common problems in wide fractures. These will be key issues to address in future work. Although gels can exhibit disproportionate permeability reduction in fractures, the levels of permeability reduction for oil flow are too high to allow practical exploitation in most circumstances. In contrast, disproportionate permeability reduction provided by gels that form in porous rock (adjacent to the fractures) has considerable potential in fractured systems.

Randall S. Seright

2004-09-30

58

Gel Electrophoresis  

NSDL National Science Digital Library

This interactive activity from the Dolan DNA Learning Center illustrates the process of gel electrophoresis, in which DNA fragments are separated by size as they migrate at different rates through a gel matrix.

Foundation, Wgbh E.

2007-04-19

59

Gel Electrophoresis  

NSDL National Science Digital Library

In the early days of DNA manipulation, DNA fragments were laboriously separated by gravity. In the 1970s, the powerful tool of DNA gel electrophoresis was developed. This process uses electricity to separate DNA fragments by size as they migrate through a gel matrix. This animation from Cold Spring Harbor Laboratory's Dolan DNA Learning Center presents Gel Electrophoresis through a series of illustrations of the processes involved.

2012-01-20

60

Dose verification of single shot gamma knife applications using VIPAR polymer gel and MRI  

Microsoft Academic Search

This work describes an experimental procedure with potential to assess the overall accuracy associated with gamma knife clinical applications, from patient imaging and dosimetry planning to patient positioning and dose delivery using the automated positioning system of a Leksell Gamma Knife model C. The VIPAR polymer gel-MRI dosimetry method is employed due to its inherent three-dimensional feature and linear dose

P. Karaiskos; L. Petrokokkinos; E. Tatsis; A. Angelopoulos; P. Baras; M. Kozicki; P. Papagiannis; J. M. Rosiak; L. Sakelliou; P. Sandilos; L. Vlachos

2005-01-01

61

Dosimetry for radiation processing  

NASA Astrophysics Data System (ADS)

During the past few years significant advances have taken place in the different areas of dosimetry for radiation processing, mainly stimulated by the increased interest in radiation for food preservation, plastic processing and sterilization of medical products. Reference services both by international organizations (IAEA) and national laboratories have helped to improve the reliability of dose measurements. Several dosimeter systems like calorimetry, perspex, and radiochromic dye films are being improved and new systems have emerged, e.g. spectrophotometry of dichromate solution for reference and sterilization dosimetry, optichromic dosimeters in the shape of small tubes for food processing, and ESR spectroscopy of alanine for reference dosimetry. In this paper the special features of radiation processing dosimetry are discussed, several commonly used dosimeters are reviewed, and factors leading to traceable and reliable dosimetry are discussed.

Miller, Arne

62

DOSIMETRY SERVICE REQUEST ADDITION DELETION  

E-print Network

DOSIMETRY SERVICE REQUEST ADDITION DELETION Use only this form and submit the completed form only for initiation of dosimetry service. If you have no occupational exposure to radiation this calendar year, write dosimetry, information will be furnished to the dosimetry vendor to provide lifetime tracking of dose

63

Polyelectrolyte gels  

SciTech Connect

Polyelectrolyte (PE) gels are swollen polymer/solvent networks that undergo a reversible volume collapse/expansion through various types of stimulation. Applications that could exploit this large deformation and solvent expulsion/absorption characteristics include robotic {open_quotes}fingers{close_quotes} and drug delivery systems. The goals of the research were to first explore the feasibility of using the PE gels as {open_quotes}smart materials{close_quotes} - materials whose response can be controlled by an external stimulus through a feedback mechanism. Then develop a predictive capability to simulate the dynamic behavior of these gels. This involved experimentally characterizing the response of well-characterized gels to an applied electric field and other stimuli to develop an understanding of the underlying mechanisms which cause the volume collapse. Lastly, the numerical analysis tool was used to simulate various potential engineering devices based on PE gels. This report discusses the pursuit of those goals through experimental and computational means.

Segalman, D.J.; Witkowski, W.R.

1995-06-01

64

Equations of state for ideal elastomeric gels  

NASA Astrophysics Data System (ADS)

Submerged in a solvent-containing environment and subject to applied forces, a covalent polymer network absorbs the solvent and deforms, forming an elastomeric gel. The equations of state are derived under two assumptions. First, the amount of the solvent in the gel varies when the gel changes volume, but remains constant when the gel changes shape. Second, the Helmholtz free energy of the gel is separable into the contribution due to stretching the network and that due to mixing the polymer and the solvent. We demonstrate that these equations of state fit several sets of experimental data in the literature remarkably well.

Cai, Shengqiang; Suo, Zhigang

2012-02-01

65

Polyelectrolyte gels  

Microsoft Academic Search

Polyelectrolyte (PE) gels are swollen polymer\\/solvent networks that undergo a reversible volume collapse\\/expansion through various types of stimulation. Applications that could exploit this large deformation and solvent expulsion\\/absorption characteristics include robotic {open_quotes}fingers{close_quotes} and drug delivery systems. The goals of the research were to first explore the feasibility of using the PE gels as {open_quotes}smart materials{close_quotes} - materials whose response can

D. J. Segalman; W. R. Witkowski

1995-01-01

66

Optically stimulated luminescence dosimetry  

Microsoft Academic Search

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

Stephen W. S. McKeever

2001-01-01

67

Dosimetry of administered radionuclides  

SciTech Connect

This volume provides the Proceedings of the Symposium on Dosimetry of Administered Radionuclides held September 21 and 22, 1989 in Washington DC. The sixteen individual presentations are indexed and abstracted separately for the database.

Adelstein, S.J.; Kassis, A.I. (eds.) (Harvard Medical School, Boston, MA (United States)); Burt, R.W. (ed.) (Indiana Univ. School of Medicine, IN (United States))

1989-01-01

68

Internal dosimetry software comparison  

E-print Network

INTERNAL DOSIMETRy SOFTWARE COMPARISON A Thesis by JUDITH RENEE FULMER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1992 Major... Subject: Health Physics INTERNAL DOSIMETRY SOFTWARE COMPARISON A Thesis by JUDITH RENEE FULMER Approved as to style and content by: John W. Poston, Sr. (Chair of Committee) Wesley E. Bolch (Member) Dan Hightower (Member) John W. Poston, Sr. (Head...

Fulmer, Judith Renee

2012-06-07

69

A unified approach to photon and beta particle dosimetry  

Microsoft Academic Search

The purpose of this investigation was to develop a unified and practical method for photon and beta particle dosimetry. This was achieved by developing a point-source function that is equally valid for photons and beta particles. This function contains four fitting parameters. These were computed on the basis of Berger`s tables for a wide range of photon and beta particle

Leichner

1994-01-01

70

Investigation on Tissue Equivalent Normoxic Polymer Gel Dosimeter using In-house Laser CT scanning system  

NASA Astrophysics Data System (ADS)

Optical Computed Tomography has wide applications in the treatment of cancer. In continuation of this, an in-house Laser CT scanner has been built for "3D gel dosimetry". The Laser CT (LCT) scanner plays a major for Gel dosimeter or phantom readout and in clinical radiation therapy as a 3-Dimensional Radiation Dosimetry. A gel dosimeter which absorbs dose in a tissue-equivalent manner and allows the measurement of spatial distribution of the deposited dose is required. The normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When laser passes through this gel phantom, absorption and scattering takes place and combined to attenuation. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by means of a sensor. Reconstruction using Mat Lab algorithm provides 3D dose distribution.

Senthil Kumar, D.; Jebaseelan Samuel, E. James

2010-11-01

71

Monte Carlo simulations to optimize experimental dosimetry of narrow beams used in Gamma Knife radio-surgery  

NASA Astrophysics Data System (ADS)

The Leksell Gamma Knife is a stereotactic radio-surgery unit for the treatment of small volumes (on the order of 25 mm 3) that employs a hemispherical configuration of 201 60Co sources and appropriate configurations of collimation to form beams of 4, 8, 14 and 18 mm nominal diameter at the Unit Center Point (UCP). Although Monte Carlo (MC) simulation is well suited for narrow-beam dosimetry, experimental dosimetry is required at least for acceptance testing and quality assurance purposes. Besides other drawbacks of conventional point dosimeters, the main problems associated with narrow-beam dosimetry in stereotactic applications are accurate positioning and volume averaging. In this work, MCNPX and EGSnrc MC simulation dosimetry results for a Gamma Knife unit are benchmarked through their comparison to treatment planning software calculations based on radio-chromic film measurements. Then, MC dosimetry results are utilized to optimize the only three-dimensional experimental dosimetry method available; the polymer gel-Magnetic Resonance Imaging (MRI) method. MC results are used to select the spatial resolution in the imaging session of the irradiated gels and validate a mathematical tool for the localization of the UCP in the three-dimensional experimental dosimetry data acquired. Experimental results are compared with corresponding MC calculations and shown capable to provide accurate dosimetry, free of volume averaging and positioning uncertainties.

Lymperopoulou, G.; Petrokokkinos, L.; Papagiannis, P.; Steiner, M.; Spevacek, V.; Semnicka, J.; Dvorak, P.; Seimenis, I.

2007-09-01

72

A study on the role of gelatin in methacrylic-acid-based gel dosimeters  

Microsoft Academic Search

In radiotherapy treatment, polymer gel dosimetry can be used for verifying three-dimensional (3D) dose distributions. Gelatin is generally used as a gelling agent in the dosimeters. In this paper, another role of gelatin in a methacrylic-acid-based gel dosimeter (MAGAT) is investigated. Temperature increases due to exothermic polymerization in the irradiated gel are measured directly. Dose–R2 responses are also obtained using

Shin-Ichiro Hayashi; Munenori Yoshioka; Shuji Usui; Kiyofumi Haneda; Takahiro Kondo; Kim B. McAuley; Takahiro Tominaga

2010-01-01

73

Dosimetry considerations in phototherapy  

Microsoft Academic Search

Dosimetry in phototherapy involves a determination of the energy absorbed per unit mass of tissue, corrected for the quantum yield in a photochemical reaction. The dose rate in photochemotherapy of cancer with hematoporphyrin derivative and visible light is related to the extinction coefficient, quantum yield for singlet oxygen production, concentration of sensitizer and energy flux density at depth. Data or

A. Edward Profio; D. R. Doiron

1981-01-01

74

Ion-kill dosimetry  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

75

Men's Fitness  

NSDL National Science Digital Library

It seems that people in the United States are going through a new and renewed commitment to getting back in shape, and there are a variety of helpful online resources to make this a viable possibility for millions of Americans. This particular site (sponsored by a number of fitness-related publications) brings together information on a host of timely topics, including weight loss, healthy eating, building muscle mass, and seasonal training suggestions. The homepage contains links on such topics as diminishing cellulite and eating organic, and also contains a number of online calculators. These calculators can help individuals determine their body mass index, their weight loss potential, and their ideal weight. The site also has an area where visitors can sign up to receive any number of free electronic newsletters from some of the magazines that sponsor the site.

76

Results from 2010 Caliban Criticality Dosimetry Intercomparison.  

National Technical Information Service (NTIS)

The external dosimetry program participated in a criticality dosimetry intercomparison conducted at the Caliban facility in Valduc, France in 2010. Representatives from the dosimetry and instrumentation groups were present during testing which included ir...

2011-01-01

77

In vivo dosimetry for IMRT  

SciTech Connect

In vivo dosimetry has a well established role in the quality assurance of 2D radiotherapy and 3D conformal radiotherapy. The role of in vivo dosimetry for IMRT is not as well established. IMRT introduces a range of technical issues that complicate in vivo dosimetry. The first decade or so of IMRT implementation has largely relied upon pre-treatment phantom based dose verification. During that time, several new devices and techniques for in vivo dosimetry have emerged with the promise of providing the ultimate form of IMRT dose verification. Solid state dosimeters continue to dominate the field of in vivo dosimetry in the IMRT era. In this report we review the literature on in vivo dosimetry for IMRT, with an emphasis on clinical evidence for different detector types. We describe the pros and cons of different detectors and techniques in the IMRT setting and the roles that they are likely to play in the future.

Vial, Philip [Department of Medical Physics, Liverpool Cancer Therapy Centre (Australia); Institute of Medical Physics, School of Physics, University of Sydney (Australia)

2011-05-05

78

Laser CT evaluation on normoxic PAGAT gel dosimeter  

NASA Astrophysics Data System (ADS)

Optical computed tomography has been shown to be a potentially useful imaging tool for the radiation therapy physicists. In radiation therapy, researchers have used optical CT for the readout of 3D dosimeters. The purpose of this paper is to describe the initial evaluation of a newly fabricated laser CT scanner for 3D gel dosimetry which works using the first generation principle. A normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When a laser passes through the gel phantom, absorption and scattering of photon take place. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by a sensor. The scanner motion is controlled by a computer program written in Microsoft Visual C++. Reconstruction and data analysis on the irradiated gel phantom is performed by suitable algorithm using Matlab software.

Kumar, D. S.; Samuel, E. J. J.; Watanabe, Y.

2013-06-01

79

Thorium metabolism and dosimetry  

SciTech Connect

Thorium occurs widely in nature, and has been used in medicine, industry, and advanced nuclear fuel cycles. Despite many studies, there still remains uncertainty in the dosimetry of Th, particularly that associated with the Th-232 decay chain. This presentation reviews past and current uses of thorium, and describes the residual difficulties involved with monitoring methods and calculations used in both environmental and occupational exposure evaluations.

Johnson, J.R.; Hill, R.L. [Pacific Northwest Lab., Richland, WA (United States); Birchall, A.; Jarvis, N.S. [National Radiological Protection Board, Chilton (United Kingdom)

1994-07-01

80

Fifth personnel dosimetry intercomparison study  

Microsoft Academic Search

The fifth Personnel Dosimetry Intercomparison Study (PDIS) was conducted at the Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research (DOSAR) facility on March 20-22, 1979. This study is the latest PDIS in the continuing series started at the DOSAR facility in 1974. The PDIS is a three day study, typically in March, where personnel dosimeters are mailed to the DOSAR

Sims

1980-01-01

81

Thermolumineszenz in Dosimetrie und Geowissenschaften  

NASA Astrophysics Data System (ADS)

Es wird ein Überblick über neue Ergebnisse und Erfahrungen bei der Anwendung thermolumineszierender Stoffe in der Dosimetrie und in den Geowissenschaften gegeben.Schwerpunkte bilden die Bestimmung der Eigenschaften und Wechselwirkungsparameter von Speicherphosphoren sowie ihr Einsatz zur Dosimetrie in Neutronen-Gamma-Feldern. Ferner werden einige Möglichkeiten beschrieben, mit Hilfe der Thermolumineszenz das Alter von Sedimenten, vulkanischen Gesteinen und von Steinmeteoriten zu bestimmen sowie Minerale unterschiedlicher Genese zu charakterisieren.Translated AbstractThermoluminescence in Dosimetry and GeosciencesNew results and experiences in the application of thermoluminescent materials in the dosimetry and geosciences are surveyed.Main topics are the determination of the properties and interaction parameters of luminophors and their use for dosimetry in neutron-gamma fields. Furthermore some possibilities are described for determinating the age of sediments, volcanic rocks and stony meteorites with the aid of thermoluminescence as well as for characterizing of minerals of different genesis.

Herforth, L.; Hübner, K.; Stolz, W.

82

A unified approach to photon and beta-particle dosimetry  

Microsoft Academic Search

The purpose of this investigation was to develop a unified method for photon and beta-particle dosimetry. This was achieved by developing a point-source function that is equally valid for photons and beta particles. This function contains four fitting parameters. These were computed on the basis of Berger`s tables for the energy deposition in water by photons from point sources and

Leichner

1994-01-01

83

Fast neutron dosimetry  

SciTech Connect

This progress report concentrates on two major areas of dosimetry research: measurement of fast neutron kerma factors for several elements for monochromatic and white spectrum neutron fields and determination of the response of thermoluminescent phosphors to various ultra-soft X-ray energies and beta-rays. Dr. Zhixin Zhou from the Shanghai Institute of Radiation Medicine, People's Republic of China brought with him special expertise in the fabrication and use of ultra-thin TLD materials. Such materials are not available in the USA. The rather unique properties of these materials were investigated during this grant period.

DeLuca, P.M. Jr.; Pearson, D.W.

1992-01-01

84

Status of radiation processing dosimetry  

NASA Astrophysics Data System (ADS)

Several milestones have marked the field of radiation processing dosimetry since IMRP 7. Among them are the IAEA symposium on High Dose Dosimetry for Radiation Processing and the international Workshops on Dosimetry for Radiation Processing organized by the ASTM. Several standards have been or are being published by the ASTM in this field, both on dosimetry procedures and on the proper use of specific dosimeter systems. Several individuals are involved in this international cooperation which contribute significantly to the broader understanding of the role of dosimetry in radiation processing. The importance of dosimetry is emphasized in the standards on radiation sterilization which are currently drafted by the European standards organization CEN and by the international standards organization ISO. In both standards, dosimetry plays key roles in characterization of the facility, in qualification of the process and in routine process control. As a function of the work on the standards, several issues are now receiving major attention. These include traceability and uncertainty limits of the dose measurements, calibration procedures, environmental influence and combination of influence factors such as dose rate and temperature. The increased attention to these factors have increased the demands on existing dosimeter systems, and rather than new dosimeters, the latest years have seen improvements on established dosimeters.

Miller, Arne

1993-10-01

85

Liquid radiochromic dosimetry  

NASA Astrophysics Data System (ADS)

By strategic combination of weak acid, mild oxidizing agent, and polar organic solvents containing millimolar concentrations of leucocyanides of certain triphenylmethane dyes, fairly broad ranges of absorbed doses of ionizing radiation can be determined. The yield of dye ions as determined by spectrophotometry can be made essentially constant with dose (i.e. linear response) from 0.01 to 30 kGy and it does not vary with dose rate upto 10 11 Gy·s -1. The radiation-induced color is stable and offers fast-retrieval dosimetry if N-vinyl-2-pyrrolidone is used as solvent. Other possible polar solvents are 2-propanol, 2-methoxy ethanol, N, N-dimethyl formamide, dimethyl sulfoxide, and triethyl phosphate. Dimethyl sulfoxide is found to give the widest and most linear response. Suitable dye precursors are leucocyanides of pararosaniline, new fuchsin, hexa (hydroxyethyl) pararosaniline, crystal violet, malachite green, setoglaucine, ethyl violet, helvetia green, basic violet-14, and formyl violet. Low concentrations of carboxylic acids contribute stability to the system. Typical mild oxidizing agents are nitrobenzene, and atmospheric oxygen, or oxygen released radiolytically from the solvents. The dosimetry systems do not require high-purity of ingredients or ultracleanliness of containers, although, for reproducibility of dye yields (G-values), thoroughly purified and uniform dye derivates are recommended.

Rativanich, N.; Radak, B. B.; Miller, A.; Uribe, R. M.; McLaughlin, W. L.

86

The radiation dosimetry of In-111 pentetreotide  

SciTech Connect

In-111 Pentetreotide is a somatostatin receptor imaging agent for use in the scintigraphic localization of neuroendocrine tumors. Biokinetic data were gathered in two centers for determining the radiation dosimetry of this agent. In total, 10 patients were studied; their data were pooled to provide a single set of dose estimates. Scintigraphic data were used to quantify the activity in kidneys, liver, and spleen. Activity excreted in urine was also measured up to 48 hours post injection. These data were fit to a multicompartmental model using the Simulation Analysis And Modeling (SAAM) software. Excretion through the gastrointestinal (GI) tract was treated using the standard kinetic model of ICRP Publication 30, with input from the liver as determined by conservation of activity in the remainder of the model (no enterohepatic recycling was assumed). Residence times for the major organs (including GI organs) were averaged. Radiation dose estimates for all organs of the body, and the effective dose equivalent (EDE), were estimated using the MIRDOSE 3 software. Kidneys, spleen, and urinary bladder are all estimated to receive between 0.3 and 0.5 mGy/MBq. The lower large intestine wall receives approximately 0.08 mGy/MBq; all is approximately 0.1 mSv/MBq. These data should be used as the basis for the dosimetry of this agent.

Stabin, M.G. [Oak Ridge Inst. for Science and Education, TN (United States); Kooij, P.P.M.; Bakker, W.H. [Univ. Hospital Dijkzigt, Rotterdam (Netherlands)] [and others

1995-05-01

87

Field House Fitness program  

E-print Network

/Toning or Mind/ Body classes. A 12-punch card is also available if the FitPass doesn't fit your superhero superhero can hone up on their strength, flexibility, coordination, and lung capacity. fitness program #12

van den Berg, Jur

88

Internal dosimetry technical basis manual  

SciTech Connect

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

Not Available

1990-12-20

89

Hanford internal dosimetry program manual  

SciTech Connect

This document describes the Hanford Internal Dosimetry program. Program Services include administrating the bioassay monitoring program, evaluating and documenting assessments of internal exposure and dose, ensuring that analytical laboratories conform to requirements, selecting and applying appropriate models and procedures for evaluating internal radionuclide deposition and the resulting dose, and technically guiding and supporting Hanford contractors in matters regarding internal dosimetry. 13 refs., 16 figs., 42 tabs.

Carbaugh, E.H.; Sula, M.J.; Bihl, D.E.; Aldridge, T.L.

1989-10-01

90

Neutron personnel dosimetry intecomparison studies  

Microsoft Academic Search

The Dosimetry Applications Research (DOSAR) Group at the Oak Ridge National Laboratory (ORNL) has conducted sixteen Neutron Personnel Dosimetry Intercomparison Studies (PDIS) since 1974. During these studies dosimeters are mailed to DOSAR, exposed to low-level (typically in the 0.3 -- 5.0 mSv range) neutron dose equivalents in a variety of mixed neutron-gamma radiation fields, and then returned to the participants

Sims

1991-01-01

91

Fourth Personnel Dosimetry Intercomparison Study  

Microsoft Academic Search

The fourth Personnel Dosimetry Intercomparison Study was held at the Oak Ridge National Laboratory's Dosimetry Applications Research Facility during March 15-23, 1978. The Health Physics Research Reactor (HPRR) used unshielded, with a 12-cm-thick Lucite shield, a 20-cm-thick concrete shield, or a 5-cm-thick steel and 15-cm-thick concrete shield, and provided four neutron and gamma-ray spectra. Then the dose was calculated based

1980-01-01

92

Dosimetry during space missions  

NASA Technical Reports Server (NTRS)

Comparative radiation hazards due to various sources of radiation in several prominent manned space missions are surveyed, along with techniques for coping with the hazards. Cosmic radiation of solar and galactic origin, and Van Allen belt radiation, are the major hazards outside the earth's geomagnetic shield, and were a major problem in the Apollo missions. The Skylab missions, while within the geomagnetic field, were subject to extensive exposure to the trapped radiation belts (Van Allen belts), while the Soyuz-Apollo test project involved orbiting at a lower altitude, with lower exposure. No solar particle bursts affected Apollo missions, and the Solar Particle Alert Network devised to help cope with the problem is described. Dosimetry practices and devices are described. Radiation experience and dose readings logged with the various missions are reported.

Bailey, J. V.

1976-01-01

93

Applied beta dosimetry  

SciTech Connect

The science or art of beta dosimetry is as old as the Nuclear Industry itself but still is poorly understood. Many practicing health physicists have thought the detection, measurement, and evaluation of beta dose and/or dose rates to be a solved problem, accepting reported field survey readings and personnel dose measurements at face value. However, beta doses (primarily a skin dose), if measured at all, are generally inaccurate at best. Field measurements of beta-gamma dose rates are equally difficult, and estimation of personnel dosimeter results from field surveys have proven to be suprising, frustrating, and risky. Beta calibration sources have not been available in the intensity and energy ranges needed and, in general, have not been adequately characterized for either intensity or energy spectra vs distance. The purposes of this report are to discuss the current industry capabilities, highlighting pitfalls for the applied health physics personnel, and briefly outlining preferred practices.

Rich, B.L.

1982-06-01

94

Medical dosimetry in Hungary  

NASA Astrophysics Data System (ADS)

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

Turák, O.; Osvay, M.; Ballay, L.

2012-09-01

95

Chemical dosimetry in the near zone of brachytherapy sources  

NASA Astrophysics Data System (ADS)

New treatment methods and technical advances in the field of radiation oncology have challenged Medical Physicists to design sophisticated dosimeters to measure the dose in the near-zone of brachytherapy sources. To accurately map steep dose-gradients in the near-zone the detector should not perturb the radiation field and should be tissue equivalent, energy independent, and dose rate independent. The treatment of neointimal hyperplasia, prostate cancer with permanent brachytherapy seed implants, and transition zone effects in 3-D conformal therapy has spurred the development of new dosimeters and apparatuses for evaluating steep dose-gradient regions. This project has developed two dosimetry systems to accurately measure the radial dose in the near-zone of clinically used 137Cs and 192Ir sources. A polymer gel dosimeter was designed and implemented for this project. This study represents the first attempt to use a custom-made polymer gel dosimeter to exclusively investigate the radial dose in the near-zone of brachytherapy sources. The custom-made polymer gel dosimeter in conjunction with a high-field strength small-bore MR scanner was determined to provide accurate and reproducible data of the dose in the near-zone. A second dosimetry system consisted of gaf-chromic film- 'the gold standard'-and a custom-built precision scanner. The scanner was designed with a 670nm wave length diode-laser and precision-built micrometers for scanning. The scanner provided optimal scanning conditions for the gaf-chromic film. The gaf-chromic film data for the radial dose in the near-zone of the clinically used 137Cs and 192Ir sources agreed well with the data from the polymer gel dosimeter. This project has confirmed the radial dose results in the near-zone of the often-cited Monte-Carlo data of Williamson. The polymer gel and the gaf-chromic film radial dose data agree well with the Monte-Carlo data in the near-zone of a single 137Cs source and a single 192Ir seed. This project has extended the reliable data in the near-zone from 3mm down to 1mm. Both detectors were shown to be excellent candidates for near- zone dosimetry, and have created an empirical benchmark for the Monte-Carlo theorist.

Hasson, Brian Fitzgerald

96

Physical Fitness Assessment.  

ERIC Educational Resources Information Center

This document presents baseline data on physical fitness that provides an outline for assessing the physical fitness of students. It consists of 4 tasks and a 13-item questionnaire on fitness-related behaviors. The fitness test evaluates cardiorespiratory endurance by a steady state jog; muscular strength and endurance with a two-minute bent-knee…

Valdes, Alice

97

Running an Agarose Gel  

NSDL National Science Digital Library

This video adapted from the University of Leicester provides step-by-step instructions for loading samples into an agarose gel and then running the gel to separate DNA molecules according to their size.

Foundation, Wgbh E.

2011-11-07

98

Health physics research reactor reference dosimetry  

Microsoft Academic Search

Reference neutron dosimetry is developed for the Health Physics Research Reactor (HPRR) in the new operational configuration directly above its storage pit. This operational change was physically made early in CY 1985. The new reference dosimetry considered in this document is referred to as the 1986 HPRR reference dosimetry and it replaces any and all HPRR reference documents or papers

C. S. Sims; G. E. Ragan

1987-01-01

99

Nuclear accident dosimetry intercomparison studies.  

PubMed

Twenty-two nuclear accident dosimetry intercomparison studies utilizing the fast-pulse Health Physics Research Reactor at the Oak Ridge National Laboratory have been conducted since 1965. These studies have provided a total of 62 different organizations a forum for discussion of criticality accident dosimetry, an opportunity to test their neutron and gamma-ray dosimetry systems under a variety of simulated criticality accident conditions, and the experience of comparing results with reference dose values as well as with the measured results obtained by others making measurements under identical conditions. Sixty-nine nuclear accidents (27 with unmoderated neutron energy spectra and 42 with eight different shielded spectra) have been simulated in the studies. Neutron doses were in the 0.2-8.5 Gy range and gamma doses in the 0.1-2.0 Gy range. A total of 2,289 dose measurements (1,311 neutron, 978 gamma) were made during the intercomparisons. The primary methods of neutron dosimetry were activation foils, thermoluminescent dosimeters, and blood sodium activation. The main methods of gamma dose measurement were thermoluminescent dosimeters, radiophotoluminescent glass, and film. About 68% of the neutron measurements met the accuracy guidelines (+/- 25%) and about 52% of the gamma measurements met the accuracy criterion (+/- 20%) for accident dosimetry. PMID:2777549

Sims, C S

1989-09-01

100

Space radiation dosimetry  

SciTech Connect

Dosimetry is the measurement of the energy deposited in matter by various forms of radiation. In space the radiation is primarily energetic electrons, protons and heavier ions from planetary radiation belts, solar flares, and interstellar cosmic rays. Experimentally, dose is frequently obtained by summing the individual energy deposits in a solid state detector. If the detector is calibrated and the sensitive mass is known, the energy sum can be converted directly to accumulated radiation dose in Gy (J/kg). Such detectors can also be used to provide an approximate separation of dose into the components due to electrons, protons, and heavier ions, which is useful if it is desired to convert the measured dose into a biological effective dose (Sv) for manned spaceflight purposes. The output can also be used to provide an essentially instantaneous dose rate for use as warning devices. This is the primary type of space radiation dosimeter to be discussed here. The MOS-type dosimeter is another solid state sensor which can be of small size and low power. These devices integrate the total dose once through, can not separate particle types, and are not suitable for instantaneous dose rate measurement at low levels. There are several additional methods of measuring space radiation dose using scintillators, etc., but are not discussed in detail. In this paper emphasis is given to descriptions of active solid state detector instruments which have successfully worked in space. Some results of in-orbit dose measurements are presented.

Hanser, F.A.; Dichter, B.K. [Armed Forces Radiobiology Research Inst., Bethesda, MD (United States); [DLR Inst. of Aerospace Medicine, Cologne (Germany); [NASA, Goddard Space Flight Center, Greenbelt, MD (United States)

1993-12-31

101

A New Optical-CT Apparatus for 3-D Radiotherapy Dosimetry: Is Free Space Scanning Feasible?  

Microsoft Academic Search

In this paper, we present a new optical computed tomography (Optical-CT) scanner for the verification of the radiation dose schemes delivered in modern radiotherapy applications. The optical-CT scanner is capable of providing rapid relative 3-D dosimetry with high spatial resolution with the use of normoxic N-Vinylpyrrolidone based polymer gel dosimeter. The scanner employs a diffuse uncollimated light illumination beam, a

Antonios E. Papadakis; Giannis Zacharakis; Thomas G. Maris; Jorge Ripoll; John Damilakis

2010-01-01

102

Kids and Fitness.  

ERIC Educational Resources Information Center

Too many U.S. children are out of shape. Parents must help them learn to improve their fitness by exercising with them. The U.S. Conference of Mayors recently made physical fitness of the nation's children a primary emphasis. A sidebar presents information on how to contact local mayors to start up programs to help children improve their fitness.…

Corradini, Deedee

1999-01-01

103

National Fitness Boom.  

ERIC Educational Resources Information Center

Facts and figures about the growth of the physical fitness phenomenon in the United States are discussed. Millions participate in physical fitness activities and programs, and billions are spent on fitness. Better leadership, facilities, and programs are available than ever before. (PP)

Conrad, C. Carson

1983-01-01

104

Surveillance dosimetry: achievements and disappointments  

Microsoft Academic Search

A methodology has been developed for reducing the uncertainties in estimates of neutron fluence spectra within the pressure vessel of a PWR from dosimetry measurements performed at a surveillance location. This new procedure, named the LEPRICON methodology, has three desirable features not presently available in other spectral unfolding codes: (1) the derivation of flux covariances at each of the two

J. J. Wagschal; R. E. Maerker; B. L. Broadhead

1982-01-01

105

CONFORMANCE IMPROVEMENT USING GELS  

SciTech Connect

This report describes work performed during the second year of the project, ''Conformance Improvement Using Gels.'' The project has two objectives. The first objective is to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective is to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil. Pore-level images from X-ray computed microtomography were re-examined for Berea sandstone and porous polyethylene. This analysis suggests that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than a gel-ripping mechanism. This finding helps to explain why aqueous gels can reduce permeability to water more than to oil. We analyzed a Cr(III)-acetate-HPAM gel treatment in a production well in the Arbuckle formation. The availability of accurate pressure data before, during, and after the treatment was critical for the analysis. After the gel treatment, water productivity was fairly constant at about 20% of the pre-treatment value. However, oil productivity was stimulated by a factor of 18 immediately after the treatment. During the six months after the treatment, oil productivity gradually decreased to approach the pre-treatment value. To explain this behavior, we proposed that the fracture area open to oil flow was increased substantially by the gel treatment, followed by a gradual closing of the fractures during subsequent production. For a conventional Cr(III)-acetate-HPAM gel, the delay between gelant preparation and injection into a fracture impacts the placement, leakoff, and permeability reduction behavior. Formulations placed as partially formed gels showed relatively low pressure gradients during placement, and yet substantially reduced the flow capacity of fractures (with widths from 1 to 4 mm) during brine and oil flow after placement. Regardless of gel age before placement, very little gel washed out from the fractures during brine or oil flow. However, increased brine or oil flow rate and cyclic injection of oil and water significantly decreased the level of permeability reduction. A particular need exists for gels that can plug large apertures (e.g., wide fractures and vugs). Improved mechanical strength and stability were demonstrated (in 1- to 4-mm-wide fractures) for a gel that contained a combination of high- and low-molecular weight polymers. This gel reduced the flow capacity of 2- and 4-mm-wide fractures by 260,000. In a 1-mm-wide fracture, it withstood 26 psi/ft without allowing any brine flow through the fracture. Cr(III)-acetate-HPAM gels exhibited disproportionate permeability reduction in fractures. The effect was most pronounced when the gel was placed as gelant or partially formed gels. The effect occurred to a modest extent with concentrated gels and with gels that were ''fully formed'' when placed. The effect was not evident in tubes. We explored swelling polymers for plugging fractures. Polymer suspensions were quickly prepared and injected. In concept, the partially dissolved polymer would lodge and swell to plug the fracture. For three types of swelling polymers, behavior was promising. However, additional development is needed before their performance will be superior to that of conventional gels.

Randall S. Seright

2003-09-01

106

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing...possible, shall provide nuclear accident dosimetry for those individuals. (b)...

2013-01-01

107

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing...possible, shall provide nuclear accident dosimetry for those individuals. (b)...

2010-01-01

108

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing...possible, shall provide nuclear accident dosimetry for those individuals. (b)...

2012-01-01

109

10 CFR 835.1304 - Nuclear accident dosimetry.  

...2014-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing...possible, shall provide nuclear accident dosimetry for those individuals. (b)...

2014-01-01

110

10 CFR 835.1304 - Nuclear accident dosimetry.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304...Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing...possible, shall provide nuclear accident dosimetry for those individuals. (b)...

2011-01-01

111

Leak test fitting  

DOEpatents

A hollow fitting for use in gas spectrometry leak testing of conduit joints is divided into two generally symmetrical halves along the axis of the conduit. A clip may quickly and easily fasten and unfasten the halves around the conduit joint under test. Each end of the fitting is sealable with a yieldable material, such as a piece of foam rubber. An orifice is provided in a wall of the fitting for the insertion or detection of helium during testing. One half of the fitting also may be employed to test joints mounted against a surface.

Pickett, Patrick T. (Kettering, OH)

1981-01-01

112

New millennium frontiers of luminescence dosimetry.  

PubMed

What are the new frontiers' facing us in the new millennium with respect to luminescence dosimetry? I suggest that the first is in methodology. The fast, sensitive optically stimulated luminescence (OSL) techniques developed recently have yielded the potential for rapid environmental monitoring, multiple measurements, dose imaging, and fast readout. New vistas of applications in medical dosimetry and remote dosimetry have opened. A second frontier is literally 'out of this world'--namely, space dosimetry. Extended stays in low Earth orbit and the potential for a 1000-day mission to Mars emphasise the challenges of dosimetry in this unique radiation environment. What role does luminescence dosimetry play in this field? This talk explores the possibilities and the challenges as we seek to penetrate these new frontiers. PMID:12382823

McKeever, S W S

2002-01-01

113

Modeling chemoresponsive polymer gels.  

PubMed

Stimuli-responsive gels are vital components in the next generation of smart devices, which can sense and dynamically respond to changes in the local environment and thereby exhibit more autonomous functionality. We describe recently developed computational methods for simulating the properties of such stimuli-responsive gels in the presence of optical, chemical, and thermal gradients. Using these models, we determine how to harness light to drive shape changes and directed motion in spirobenzopyran-containing gels. Focusing on oscillating gels undergoing the Belousov-Zhabotinksy reaction, we demonstrate that these materials can spontaneously form self-rotating assemblies, or pinwheels. Finally, we model temperature-sensitive gels that encompass chemically reactive filaments to optimize the performance of this system as a homeostatic device for regulating temperature. These studies could facilitate the development of soft robots that autonomously interconvert chemical and mechanical energy and thus perform vital functions without the continuous need of external power sources. PMID:24498954

Kuksenok, Olga; Deb, Debabrata; Dayal, Pratyush; Balazs, Anna C

2014-01-01

114

Results from 2010 Caliban Criticality Dosimetry Intercomparison  

SciTech Connect

The external dosimetry program participated in a criticality dosimetry intercomparison conducted at the Caliban facility in Valduc, France in 2010. Representatives from the dosimetry and instrumentation groups were present during testing which included irradiations of whole-body beta/gamma (HBGT) and neutron thermoluminescent dosimeters (TLDs), a fixed nuclear accident dosimeter (FNAD), electronic alarming dosimeters, and a humanoid phantom filled with reference man concentrations of sodium. This report reviews the testing procedures, preparations, irradiations, and presents results of the tests.

Veinot, K. G.

2011-10-12

115

Best Fit for 'Bounce'  

NASA Technical Reports Server (NTRS)

The mineralogy of 'Bounce' rock was determined by fitting spectra from a library of laboratory minerals to the spectrum of Bounce taken by the Mars Exploration Rover Opportunity's miniature thermal emission spectrometer. The minerals that give the best fit include pyroxene, plagioclase and olivine -- minerals commonly found in basaltic volcanic rocks -- and typical martian dust produced by the rover's rock abrasion tool.

2004-01-01

116

Fun & Fitness with Balloons  

ERIC Educational Resources Information Center

The urgency to improve fitness levels and decrease the rate of childhood obesity has been at the forefront of physical education philosophy and praxis. Few would dispute that school-age youth need to participate regularly in physical activities that enhance and maintain both skill- and health-related physical fitness. Regular physical activity…

Farrell, Anne; Faigenbaum, Avery; Radler, Tracy

2010-01-01

117

Sixth personnel dosimetry intercomparison study  

Microsoft Academic Search

The Sixth Personnel Dosimetry Intercomparison Study was conducted March 25 to 27, 1980, at the Oak Ridge National Laboratory. Dosimeters from 28 participating agencies were mounted on anthropomorphic phantoms and exposed to a range of low-level dose equivalents (1.8 to 11.5 mSv neutron, 0.1 to 1.1 mSv gamma) which could be encountered during routine personnel monitoring in mixed radiation fields.

R. E. Swaja; R. T. Greene; H. W. Dickson

1981-01-01

118

Third Personnel Dosimetry Intercomparison Study  

Microsoft Academic Search

The third Personnel Dosimetery Intercomparison Study was held at the Oak Ridge National Laboratory Dosimetry Applications Research Facility during March 15--16, 1977. The Health Physics Research Reactor (HPRR), used unshielded, with a 12-cm-thick Lucite shield or a 13-cm-thick steel shield, provided three neutron and gamma-ray spectra. The characteristics of these fields such as neutron energy spectra, intensity, and uniformity had

L. W. Gilley; H. W. Dickson

1979-01-01

119

Fourth international radiopharmaceutical dosimetry symposium  

SciTech Connect

The focus of the Fourth International Radiopharmaceutical Dosimetry Symposium was to explore the impact of current developments in nuclear medicine on absorbed dose calculations. This book contains the proceedings of the meeting including the edited discussion that followed the presentations. Topics that were addressed included the dosimetry associated with radiolabeled monoclonal antibodies and blood elements, ultrashort-lived radionuclides, and positron emitters. Some specific areas of discussion were variations in absorbed dose as a result of alterations in the kinetics, the influence of radioactive contaminants on dose, dose in children and in the fetus, available instrumentation and techniques for collecting the kinetic data needed for dose calculation, dosimetry requirements for the review and approval of new radiopharmaceuticals, and a comparison of the effect on the thyroid of internal versus external irradiation. New models for the urinary blader, skeleton including the active marrow, and the blood were presented. Several papers dealt with the validity of traditional ''average-organ'' dose estimates to express the dose from particulate radiation that has a short range in tissue. These problems are particularly important in the use of monoclonal antibodies and agents used to measure intracellular functions. These proceedings have been published to provide a resource volume for anyone interested in the calculation of absorbed radiation dose.

Schlafke-Stelson, A.T.; Watson, E.E. (eds.)

1986-04-01

120

Variable transformation of calibration equations for radiation dosimetry  

NASA Astrophysics Data System (ADS)

For radiation dosimetry, dosimetric equipment must be calibrated by using known doses. The calibration is done to determine an equation that relates the absorbed dose to a physically measurable quantity. Since the calibration equation is accompanied by unavoidable uncertainties, the doses estimated with such equations suffer from inherent uncertainties. We presented mathematical formulation of the calibration when the calibration relation is either linear or nonlinear. We also derived equations for the uncertainty of the estimated dose as a function of the uncertainties of the parameters in the equations and the measured physical quantity. We showed that a dosimeter with a linear calibration equation with zero dose-offset enables us to perform relative dosimetry without calibration data. Furthermore, a linear equation justifies useful data manipulations such as rescaling the dose and changing the dose-offset for comparing dose distributions. Considering that some dosimeters exhibit linear response with a large dose-offset or often nonlinear response, we proposed variable transformations of the measured physical quantity, namely, linear- and log-transformation methods. The proposed methods were tested with Kodak X-Omat V radiographic film and BANG® polymer gel dosimeter. We demonstrated that the variable transformation methods could lead to linear equations with zero dose-offset and could reduce the uncertainty of the estimated dose.

Watanabe, Yoichi

2005-03-01

121

Variable transformation of calibration equations for radiation dosimetry.  

PubMed

For radiation dosimetry, dosimetric equipment must be calibrated by using known doses. The calibration is done to determine an equation that relates the absorbed dose to a physically measurable quantity. Since the calibration equation is accompanied by unavoidable uncertainties, the doses estimated with such equations suffer from inherent uncertainties. We presented mathematical formulation of the calibration when the calibration relation is either linear or nonlinear. We also derived equations for the uncertainty of the estimated dose as a function of the uncertainties of the parameters in the equations and the measured physical quantity. We showed that a dosimeter with a linear calibration equation with zero dose-offset enables us to perform relative dosimetry without calibration data. Furthermore, a linear equation justifies useful data manipulations such as rescaling the dose and changing the dose-offset for comparing dose distributions. Considering that some dosimeters exhibit linear response with a large dose-offset or often nonlinear response, we proposed variable transformations of the measured physical quantity, namely, linear- and log-transformation methods. The proposed methods were tested with Kodak X-Omat V radiographic film and BANG polymer gel dosimeter. We demonstrated that the variable transformation methods could lead to linear equations with zero dose-offset and could reduce the uncertainty of the estimated dose. PMID:15798318

Watanabe, Yoichi

2005-03-21

122

Agarose Gel Demos  

NSDL National Science Digital Library

This video, presented by WGBH, is a great overview of how to prepare Agarose gel for electrophoresis. The video goes in-depth with the finer points including how to insert the pipette as to not disturb the gel and get the best results. This video would be useful for anyone in biochemistry or molecular biology fields. This video would also be helpful for instructors looking to provide their students with an overview on how to prepare Agarose gel. Educators will also find a background essay, discussion questions, and standards alignment for the material.

2010-09-15

123

Limitations of inclusive fitness  

PubMed Central

Until recently, inclusive fitness has been widely accepted as a general method to explain the evolution of social behavior. Affirming and expanding earlier criticism, we demonstrate that inclusive fitness is instead a limited concept, which exists only for a small subset of evolutionary processes. Inclusive fitness assumes that personal fitness is the sum of additive components caused by individual actions. This assumption does not hold for the majority of evolutionary processes or scenarios. To sidestep this limitation, inclusive fitness theorists have proposed a method using linear regression. On the basis of this method, it is claimed that inclusive fitness theory (i) predicts the direction of allele frequency changes, (ii) reveals the reasons for these changes, (iii) is as general as natural selection, and (iv) provides a universal design principle for evolution. In this paper we evaluate these claims, and show that all of them are unfounded. If the objective is to analyze whether mutations that modify social behavior are favored or opposed by natural selection, then no aspect of inclusive fitness theory is needed. PMID:24277847

Allen, Benjamin; Nowak, Martin A.; Wilson, Edward O.

2013-01-01

124

AN Fitting Reconditioning Tool  

NASA Technical Reports Server (NTRS)

A tool was developed to repair or replace AN fittings on the shuttle external tank (ET). (The AN thread is a type of fitting used to connect flexible hoses and rigid metal tubing that carry fluid. It is a U.S. military-derived specification agreed upon by the Army and Navy, hence AN.) The tool is used on a drill and is guided by a pilot shaft that follows the inside bore. The cutting edge of the tool is a standard-size replaceable insert. In the typical Post Launch Maintenance/Repair process for the AN fittings, the six fittings are removed from the ET's GUCP (ground umbilical carrier plate) for reconditioning. The fittings are inspected for damage to the sealing surface per standard operations maintenance instructions. When damage is found on the sealing surface, the condition is documented. A new AN reconditioning tool is set up to cut and remove the surface damage. It is then inspected to verify the fitting still meets drawing requirements. The tool features a cone-shaped interior at 36.5 , and may be adjusted at a precise angle with go-no-go gauges to insure that the cutting edge could be adjusted as it wore down. One tool, one setting block, and one go-no-go gauge were fabricated. At the time of this reporting, the tool has reconditioned/returned to spec 36 AN fittings with 100-percent success of no leakage. This tool provides a quick solution to repair a leaky AN fitting. The tool could easily be modified with different-sized pilot shafts to different-sized fittings.

Lopez, Jason

2011-01-01

125

A genipin-gelatin gel dosimeter for radiation processing  

NASA Astrophysics Data System (ADS)

Genipin, a fruit extract from Gardenia jasminoides Ellis, forms cross-links in solutions of gelatin, to form a blue hydrogel that bleaches quantitatively upon irradiation and the colour change can be measured with a spectrophotometer. With the addition of sulphuric acid this dosimeter is sufficiently sensitive for quality assurance of radiotherapy level dosimetry. Without sulphuric acid the gel has a reduced sensitivity and responds linearly with dose between 100 and 1000 Gy, making it potentially useful as a dosimeter for radiation processing applications such as the phytosanitary irradiation treatment of food. We investigated the dose response characteristics of this new formulation and found that the darker gels are more sensitive to dose and have a reduced uncertainty.

Davies, J. B.; Bosi, S. G.; Baldock, C.

2012-08-01

126

Conformance Improvement Using Gels  

SciTech Connect

This research project had two objectives. The first objective was to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective was to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil.

Seright, Randall S.; Schrader, Richard; II Hagstrom, John; Wang, Ying; Al-Dahfeeri, Abdullah; Gary, Raven; Marin; Amaury; Lindquist, Brent

2002-09-26

127

Preparation of chitosan gel  

NASA Astrophysics Data System (ADS)

Aerogel conditioning of the chitosan makes it possible to prepare porous solids of significant specific surface. The increase in the chitosan concentration or the degree of acetylation decreases the specific surface of the synthesized chitosan gel. Whereas drying with supercritical CO2 more effectively makes it possible to preserve the volume of the spheres of gel and to have a more significant specific surface in comparison with evaporative drying.

Moussaoui, Y.; Mnasri, N.; Elaloui, E.; Ben Salem, R.; Lagerge, S.; de Menorval, L. C.

2012-06-01

128

WOLF: FITS file processor  

NASA Astrophysics Data System (ADS)

WOLF processes FITS files and generates photometry files, annotated JPGs, opacity maps, background, transient detection and luminance changes detection. This software was used to process data for the Night Sky Live project.

Shamir, Lior

2012-12-01

129

The universal Higgs fit  

E-print Network

We perform a state-of-the-art global fit to all Higgs data. We synthesise them into a 'universal' form, which allows to easily test any desired model. We apply the proposed methodology to extract from data the Higgs branching ratios, production cross sections, couplings and to analyse composite Higgs models, models with extra Higgs doublets, supersymmetry, extra particles in the loops, anomalous top couplings, invisible Higgs decay into Dark Matter. Best fit regions lie around the Standard Model predictions and are well approximated by our 'universal' fit. Latest data exclude the dilaton as an alternative to the Higgs, and disfavour fits with negative Yukawa couplings. We derive for the first time the SM Higgs boson mass from the measured rates, rather than from the peak positions, obtaining $M_h = 125.0 \\pm 1.8$ GeV.

Giardino, Pier Paolo; Masina, Isabella; Raidal, Martti; Strumia, Alessandro

2014-01-01

130

Film dosimetry of megavoltage photon beams: a practical method of isodensity-to-isodose curve conversion  

Microsoft Academic Search

The central problems of photon beam film dosimetry are the dependence of film response upon photon energy, processing conditions, and film plane orientation. Researchers have overcome these problems by accurately fitting the depth-dependent sensitometric curve of Kodak XV-2 film to the equation OD(D,d) = OHs(1 - exp (- ..cap alpha.. 0(1 + ..beta..(d-dm))D)) where OD(D,d) is the optical density for

Jeffrey F. Williamson; F. M. Khan; S. C. Sharma

1981-01-01

131

Electrically controlled polymeric gel actuators  

Microsoft Academic Search

Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel

Douglas B. Adolf; Mohsen Shahinpoor; Daniel J. Segalman; Walter R. Witkowski

1993-01-01

132

Electrically controlled polymeric gel actuators  

Microsoft Academic Search

Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in

D. B. Adolf; M. Shahinpoor; D. J. Segalman; W. R. Witkowski

1993-01-01

133

Gel dosimeters as useful dose and thermal-fluence detectors in boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

The dosimetry method based on Fricke-Xylenol-Orange-infused gels in form of layers has shown noticeable potentiality for in-phantom or in-free-beam dose and thermal flux profiling and imaging in the high fluxes of thermal or epithermal neutrons utilised for boron neutron capture therapy (BNCT). Gel-dosimeters in form of layers give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. The discrimination of the various dose components is achieved by means of pixel-to-pixel manipulations of pairs of images obtained with gel-dosimeters having different isotopic composition. It is possible to place large dosimeters, detecting in such a way large dose images, because the layer geometry of dosimeters avoids sensitive variation of neutron transport due to the gel isotopic composition. Some results obtained after the last improvements of the method are reported.

Gambarini, G.; Moss, R. L.; Mariani, M.; Carrara, M.; Daquino, G. G.; Nievaart, V. A.; Valente, M.; Vanossi, E.

134

Rules, culture, and fitness  

PubMed Central

Behavior analysis risks intellectual isolation unless it integrates its explanations with evolutionary theory. Rule-governed behavior is an example of a topic that requires an evolutionary perspective for a full understanding. A rule may be defined as a verbal discriminative stimulus produced by the behavior of a speaker under the stimulus control of a long-term contingency between the behavior and fitness. As a discriminative stimulus, the rule strengthens listener behavior that is reinforced in the short run by socially mediated contingencies, but which also enters into the long-term contingency that enhances the listener's fitness. The long-term contingency constitutes the global context for the speaker's giving the rule. When a rule is said to be “internalized,” the listener's behavior has switched from short- to long-term control. The fitness-enhancing consequences of long-term contingencies are health, resources, relationships, or reproduction. This view ties rules both to evolutionary theory and to culture. Stating a rule is a cultural practice. The practice strengthens, with short-term reinforcement, behavior that usually enhances fitness in the long run. The practice evolves because of its effect on fitness. The standard definition of a rule as a verbal statement that points to a contingency fails to distinguish between a rule and a bargain (“If you'll do X, then I'll do Y”), which signifies only a single short-term contingency that provides mutual reinforcement for speaker and listener. In contrast, the giving and following of a rule (“Dress warmly; it's cold outside”) can be understood only by reference also to a contingency providing long-term enhancement of the listener's fitness or the fitness of the listener's genes. Such a perspective may change the way both behavior analysts and evolutionary biologists think about rule-governed behavior. ImagesFigure 1 PMID:22478201

Baum, William M.

1995-01-01

135

Solid-State Personal Dosimetry  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

136

Fitting Cosmological Data Package  

NSDL National Science Digital Library

The EJS Fitting Cosmological Data Launcher package includes several cosmological fitting simulations for five different observations of the expansion, all of which support a cosmic acceleration. The launcher allows users to choose which simulation to use to compare and fit theoretical models of cosmology with recent supernovae, gamma-ray bursts, the Hubble Parameter, baryon acoustic oscillations, and the CMB data sets to confirm the accelerated expansion of the universe. This modeling allows the user to vary cosmological parameters within a particular class of dark energy cosmological models to fit a particular cosmological data set. The user can plot several theoretical curves with the data to compare different models. The values of these parameters, for a particular model, determine the physical description and evolution of the universe. The EJS Fitting Cosmological Data Launcher package was created using Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_CosmoEJS.jar file will run the program if Java is installed. You can modify this simulation if you have EJS by right-clicking within the plot and selecting Open Ejs Model from the pop-up menu item.

Moldenhauer, Jacob; Stone, Keenan; Shuler, Zeke; Engelhardt, Larry

2012-09-10

137

Ames Fitness Program  

NASA Technical Reports Server (NTRS)

The Ames Fitness Program services 5,000 civil servants and contractors working at Ames Research Center. A 3,000 square foot fitness center, equipped with cardiovascular machines, weight training machines, and free weight equipment is on site. Thirty exercise classes are held each week at the Center. A weight loss program is offered, including individual exercise prescriptions, fitness testing, and organized monthly runs. The Fitness Center is staffed by one full-time program coordinator and 15 hours per week of part-time help. Membership is available to all employees at Ames at no charge, and there are no fees for participation in any of the program activities. Prior to using the Center, employees must obtain a physical examination and complete a membership package. Funding for the Ames Fitness Program was in jeopardy in December 1992; however, the employees circulated a petition in support of the program and collected more than 1500 signatures in only three days. Funding has been approved through October 1993.

Pratt, Randy

1993-01-01

138

N-isopropylacrylamide gel dosimeter to evaluate clinical photon beam characteristics.  

PubMed

The introduction of beam intensity control concept in current radiotherapy techniques has increased treatment planning complexity. Thus, small-field dose measurement has become increasingly vital. Polymer gel dosimetry method is widely studied. It is the only dose measurement tool that provides 3D dose distribution. This study aims to use an N-isopropylacrylamide (NIPAM) gel dosimeter to conduct beam performance measurements of percentage depth dose (PDD), beam flatness, and symmetry for photon beams with field sizes of 3×3 and 4×4 cm(2). Computed tomography scans were used to readout the gel dosimeters. In the PDD measurement, the NIPAM gel dosimeter and Gafchromic™ EBT3 radiochromic film displayed high consistency in the region deeper than the build-up region. The gel dosimeter dose profile had 3% lower flatness and symmetry measurement at 5 cm depth for different fields compared with that of the Gafchromic™ EBT3 film. During gamma evaluation under 3%/3 mm dose difference/distance-to-agreement standard, the pass rates of the polymer gel dosimeter to the TPS and EBT3 film were both higher than 96%. Given that the gel is tissue equivalent, it did not exhibit the energy dependence problems of radiochromic films. Therefore, the practical use of NIPAM polymer gel dosimeters is enhanced in clinical dose verification. PMID:24836904

Chiu, Chung-Yu; Tsang, Yuk-Wah; Hsieh, Bor-Tsung

2014-08-01

139

Quenching correction for volumetric scintillation dosimetry of proton beams  

PubMed Central

Purpose Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching correction method for volumetric scintillation dosimetry of proton beams. Methods Scintillation light from a miniature liquid scintillator detector was measured along the central axis of a 161.6-MeV proton pencil beam. Three-dimensional dose and LET distributions were calculated for 85.6-, 100.9-, 144.9-, and 161.6-MeV beams using a validated Monte Carlo model. LET values were also calculated using an analytical formula. A least-squares fit to the data established the empirical parameters of a quenching correction model. The light distribution in a tank of liquid scintillator was measured with a CCD camera at all four beam energies. The quenching model and LET data were used to correct the measured light distribution. Results The calculated and measured Bragg peak heights agreed within ±3% for all energies except 85.6 MeV, where the agreement was within ±10%. The quality of the quenching correction was poorer for sharp low-energy Bragg peaks because of blurring and detector size effects. The corrections performed using analytical LET values resulted in doses within 1% of those obtained using Monte Carlo LET values. Conclusion The proposed method can correct for quenching with sufficient accuracy for dosimetric purposes. The required LET values may be computed effectively using Monte Carlo or analytical methods. Future detectors should improve blurring correction methods and optimize the pixel size to improve accuracy for low-energy Bragg peaks. PMID:23257200

Robertson, Daniel; Mirkovic, Dragan; Sahoo, Narayan; Beddar, Sam

2013-01-01

140

Quenching correction for volumetric scintillation dosimetry of proton beams  

NASA Astrophysics Data System (ADS)

Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching correction method for volumetric scintillation dosimetry of proton beams. Scintillation light from a miniature liquid scintillator detector was measured along the central axis of a 161.6 MeV proton pencil beam. Three-dimensional dose and LET distributions were calculated for 85.6, 100.9, 144.9 and 161.6 MeV beams using a validated Monte Carlo model. LET values were also calculated using an analytical formula. A least-squares fit to the data established the empirical parameters of a quenching correction model. The light distribution in a tank of liquid scintillator was measured with a CCD camera at all four beam energies. The quenching model and LET data were used to correct the measured light distribution. The calculated and measured Bragg peak heights agreed within ±3% for all energies except 85.6 MeV, where the agreement was within ±10%. The quality of the quenching correction was poorer for sharp low-energy Bragg peaks because of blurring and detector size effects. The corrections performed using analytical LET values resulted in doses within 1% of those obtained using Monte Carlo LET values. The proposed method can correct for quenching with sufficient accuracy for dosimetric purposes. The required LET values may be computed effectively using Monte Carlo or analytical methods. Future detectors should improve blurring correction methods and optimize the pixel size to improve accuracy for low-energy Bragg peaks.

Robertson, Daniel; Mirkovic, Dragan; Sahoo, Narayan; Beddar, Sam

2013-01-01

141

Quenching correction for volumetric scintillation dosimetry of proton beams.  

PubMed

Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching correction method for volumetric scintillation dosimetry of proton beams. Scintillation light from a miniature liquid scintillator detector was measured along the central axis of a 161.6 MeV proton pencil beam. Three-dimensional dose and LET distributions were calculated for 85.6, 100.9, 144.9 and 161.6 MeV beams using a validated Monte Carlo model. LET values were also calculated using an analytical formula. A least-squares fit to the data established the empirical parameters of a quenching correction model. The light distribution in a tank of liquid scintillator was measured with a CCD camera at all four beam energies. The quenching model and LET data were used to correct the measured light distribution. The calculated and measured Bragg peak heights agreed within ±3% for all energies except 85.6 MeV, where the agreement was within ±10%. The quality of the quenching correction was poorer for sharp low-energy Bragg peaks because of blurring and detector size effects. The corrections performed using analytical LET values resulted in doses within 1% of those obtained using Monte Carlo LET values. The proposed method can correct for quenching with sufficient accuracy for dosimetric purposes. The required LET values may be computed effectively using Monte Carlo or analytical methods. Future detectors should improve blurring correction methods and optimize the pixel size to improve accuracy for low-energy Bragg peaks. PMID:23257200

Robertson, Daniel; Mirkovic, Dragan; Sahoo, Narayan; Beddar, Sam

2013-01-21

142

Basic investigations on the performance of a normoxic polymer gel with tetrakis-hydroxy-methyl-phosphonium chloride as an oxygen scavenger: Reproducibility, accuracy, stability, and dose rate dependence  

Microsoft Academic Search

Magnetic resonance (MR)-based polymer gel dosimetry using normoxic polymer gels, represents a new dosimetric method specially suited for high-resolution three-dimensional dosimetric problems. The aim of this study was to investigate the dose response with regard to stability, accuracy, reproducibility, and the dose rate dependence. Tetrakis-hydroxy-methyl-phosphonium chloride (THPC) is used as an oxygen scavenger, and methacrylic acid as a monomer. Accuracy,

Christian Bayreder; Ewald Moser; Dietmar Georg

2006-01-01

143

Coloring the FITS Universe  

NASA Astrophysics Data System (ADS)

A new, freely-available accessory for Adobe's widely-used Photoshop image editing software makes it much more convenient to produce presentable images directly from FITS data. It merges a fully-functional FITS reader with an intuitive user interface and includes fully interactive flexibility in scaling data. Techniques for producing attractive images from astronomy data using the FITS plugin will be presented, including the assembly of full-color images. These techniques have been successfully applied to producing colorful images for public outreach with data from the Hubble Space Telescope and other major observatories. Now it is much less cumbersome for students or anyone not experienced with specialized astronomical analysis software, but reasonably familiar with digital photography, to produce useful and attractive images.

Levay, Z. G.

2004-12-01

144

Advances in radiation therapy dosimetry  

PubMed Central

During the last decade, there has been an explosion of new radiation therapy planning and delivery tools. We went through a rapid transition from conventional three-dimensional (3D) conformal radiation therapy to intensity-modulated radiation therapy (IMRT) treatments, and additional new techniques for motion-adaptive radiation therapy are being introduced. These advances push the frontiers in our effort to provide better patient care; and with the addition of IMRT, temporal dimensions are major challenges for the radiotherapy patient dosimetry and delivery verification. Advanced techniques are less tolerant to poor implementation than are standard techniques. Mis-administrations are more difficult to detect and can possibly lead to poor outcomes for some patients. Instead of presenting a manual on quality assurance for radiation therapy, this manuscript provides an overview of dosimetry verification tools and a focused discussion on breath holding, respiratory gating and the applications of four-dimensional computed tomography in motion management. Some of the major challenges in the above areas are discussed. PMID:20098555

Paliwal, Bhudatt; Tewatia, Dinesh

2009-01-01

145

Line of Best Fit  

NSDL National Science Digital Library

When data is displayed with a scatter plot, it is often useful to attempt to represent that data with the equation of a straight line for purposes of predicting values that may not be displayed on the plot. Such a straight line is called the "line of best fit." In this activity, students discover the relationship between the fat grams and the total calories in fast food by graphing the given data, estimate the line of best fit using a strand of spaghetti, calculate the slope of that line, and translate it into an equation. Then, they use that equation to predict information not originally included in the scatter plot.

Roberts, Donna

146

Path forward for dosimetry cross sections  

SciTech Connect

In the 1980's the dosimetry community embraced the need for a high fidelity quantification of uncertainty in nuclear data used for dosimetry applications. This led to the adoption of energy-dependent covariance matrices as the accepted manner of quantifying the uncertainty data. The trend for the dosimetry community to require high fidelity treatment of uncertainty estimates has continued to the current time where requirements on nuclear data are codified in standards such as ASTM E 1018. This paper surveys the current state of the dosimetry cross sections and investigates the quality of the current dosimetry cross section evaluations by examining calculated-to-experimental ratios in neutron benchmark fields. In recent years more nuclear-related technical areas are placing an emphasis on uncertainty quantification. With the availability of model-based cross sections and covariance matrices produced by nuclear data codes, some nuclear-related communities are considering the role these covariance matrices should play. While funding within the dosimetry community for cross section evaluations has been very meager, other areas, such as the solar-related astrophysics community and the US Nuclear Criticality Safety Program, have been supporting research in the area of neutron cross sections. The Cross Section Evaluation Working Group (CSEWG) is responsible for the creation and maintenance of the ENDF/B library which has been the mainstay for the reactor dosimetry community. Given the new trends in cross section evaluations, this paper explores the path forward for the US nuclear reactor dosimetry community and its use of the ENDF/B cross-sections. The major concern is maintenance of the sufficiency and accuracy of the uncertainty estimate when used for dosimetry applications. The two major areas of deficiency in the proposed ENDF/B approach are: 1) the use of unrelated covariance matrices in ENDF/B evaluations and 2) the lack of 'due consideration' of experimental data in the evaluation. (authors)

Griffin, P.J. [Sandia National Laboratories, Albuquerque, NM 87185-1146 (United States); Peters, C.D. [Sandia Staffing Alliance, Albuquerque, NM 87110 (United States)

2011-07-01

147

Accidental and retrospective dosimetry using TL method  

NASA Astrophysics Data System (ADS)

Retrospective dosimetry is one of the most important tools of accidental dosimetry for dose estimation when dose measurement was not planned. In the affected area many objects can be applied as natural dosimeters. The paper discusses our recent investigations on various electronic components and common salt (NaCl) having useful thermoluminescence (TL) properties. Among materials investigated the electronic components of cell phones seem promising for retrospective dosimetry purposes, having high TL responses, proper glow curve peaks and the intensity of TL peaks vs. gamma dose received provided nearly linear response in the dose range of 10 mGy-1.5 Gy.

Mesterházy, D.; Osvay, M.; Kovács, A.; Kelemen, A.

2012-09-01

148

Swelling of Olympic Gels  

NASA Astrophysics Data System (ADS)

The swelling equilibrium of Olympic gels, which are composed of entangled cyclic polymers, is studied by Monte Carlo simulations. In contrast to chemically cross-linked polymer networks, we observe that Olympic gels made of chains with a larger degree of polymerization, N, exhibit a smaller equilibrium swelling degree, Q?N-0.28?0-0.72, at the same polymer volume fraction ?0 at network preparation. This observation is explained by a desinterspersion (reorganization with release of nontrapped entanglements) process of overlapping nonconcatenated rings upon swelling.

Lang, M.; Fischer, J.; Werner, M.; Sommer, J.-U.

2014-06-01

149

Mentoring that Fits  

ERIC Educational Resources Information Center

Beginning teachers enter the classroom with diverse backgrounds, training, expectations, and needs. Yet too often, write the authors, induction programs resemble a one-size-fits-all poncho rather than a well-tailored coat. Reviewing the research, the authors write that high-quality mentors, a focus on improving instruction, and allocated time are…

Grossman, Pam; Davis, Emily

2012-01-01

150

Introduction Model Fitting  

E-print Network

Simulation References Small World random networks Definition closed to birth, non-disease death, immigration Definition closed to birth, non-disease death, immigration susceptibility to disease is homogenous across ERGM Model Fitting Simulation References Poisson Mean Field random networks Definition closed to birth

Albert, Réka

151

Water Fit to Drink.  

ERIC Educational Resources Information Center

The major objective of this module is to help students understand how water from a source such as a lake is treated to make it fit to drink. The module, consisting of five major activities and a test, is patterned after Individualized Science Instructional System (ISIS) modules. The first activity (Planning) consists of a brief introduction and a…

Donovan, Edward P.

152

Making the Fitness Connection  

ERIC Educational Resources Information Center

Children's fitness levels are decreasing at an alarming rate. The Centers for Disease Control has determined that approximately 33% of children do not regularly engage in vigorous physical activity (CDC, 2002). As a result, childhood obesity has increased 100% since 1980 in the United States due to physical inactivity (CDC, 2004). A well-planned…

Brock, Sheri J.; Fittipaldi-Wert, Jeanine

2005-01-01

153

Fit for Life.  

ERIC Educational Resources Information Center

Children who hate gym grow into adults who associate physical activity with ridicule and humiliation. Physical education is reinventing itself, stressing enjoyable activities that continue into adulthood: aerobic dance, weight training, fitness walking, mountain biking, hiking, inline skating, karate, rock-climbing, and canoeing. Cooperative,…

Vail, Kathleen

1999-01-01

154

Measuring Your Fitness Progress  

MedlinePLUS

... you’re becoming more fit, such as increased energy, greater ability to perform daily tasks, or even an improved outlook on life. VISIT www.nia.nih.gov/Go4Life l Read more about increasing your activity level. l Print useful tools. l Order a free exercise guide or DVD. l Share your exercise ...

155

Gafchromic EBT2 film dosimetry in reflection mode with a novel plan-based calibration method  

SciTech Connect

Purpose:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system in reflection mode; (b) if so, can the methods used in transmission mode also be used in reflection mode; (c) is it possible to obtain accurate absolute dose measurements with Gafchromic EBT2 films; (d) which calibration method should be followed; (e) which calibration models should be used; and (f) does three-color channel dosimetry offer a significant improvement over single channel dosimetry. The purpose of this paper is to help clarify these questions. Methods: In this study, films were scanned in reflection mode, the effect of surrounding film was evaluated and the feasibility of EBT2 film dosimetry in reflection mode was studied. EBT2's response homogeneity has been reported to lead to excessive dose uncertainties. To overcome this problem, a new plan-based calibration method was implemented. Plan-based calibration can use every pixel and each of the three color channels of the scanned film to obtain the parameters of the calibration model. A model selection analysis was conducted to select lateral correction and sensitometric curve models. The commonly used calibration with fragments was compared with red-channel plan-based calibration and with three-channel plan-based calibration. Results: No effect of surrounding film was found in this study. The film response inhomogeneity in EBT2 films was found to be important not only due to differences in the fog but also due to differences in sensitivity. The best results for lateral corrections were obtained using absolute corrections independent of the dose. With respect to the sensitometric curves, an empirical polynomial fit of order 4 was found to obtain results equivalent to a gamma-distributed single hit model based on physical assumptions. Three-channel dosimetry was found to be substantially superior to red-channel dosimetry. Conclusions: Reflection mode with Gafchromic EBT2 radiochromic film was found to be a viable alternative to transmission mode. The same methods that are used in transmission mode can be followed in reflection mode. A novel plan-based method was developed for calibration and multichannel dosimetry. This novel method offers increased robustness against film response inhomogeneities and reduces considerably the time required for calibration.

Mendez, I.; Hartman, V.; Hudej, R.; Strojnik, A.; Casar, B. [Department of Medical Physics, Institute of Oncology Ljubljana, Zaloska cesta 2, Ljubljana 1000 (Slovenia)

2013-01-15

156

Data Plotting and Curve Fitting in MATLAB Curve Fitting  

E-print Network

Data Plotting and Curve Fitting in MATLAB Curve Fitting Get the file pwl.dat from the class web(1)*pwl(:,1)+fit1(2)) If you're getting tired of typing pwl(:,1), etc., create new variables with shorter]') ylabel(`Output Current [mA]') title(`Curve Fitting Exercise') It is very important to always label your

Harrison, Reid R.

157

Running an Agarose Gel  

NSDL National Science Digital Library

This video from CUNY Kingsborough Community College shows the process of running an agarose gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 2:52.

Hinkley, Craig

2013-06-17

158

Preparing an Agarose Gel  

NSDL National Science Digital Library

This video from CUNY Kingsborough Community College describes the technique of preparing an Agarose Gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 3:10.

Shun Ho, Ivan

2013-06-25

159

Pouring an Agarose Gel  

NSDL National Science Digital Library

This video from CUNY Kingsborough Community College shows how to pour an Agarose Gel. The video describes the process step by step and would be easy to replicate in a laboratory setting. Running time for the video is 2:13.

Hinkley, Craig

2013-06-26

160

Cross sections required for FMIT dosimetry  

SciTech Connect

The Fusion Materials Irradiation Test (FMIT) facility, currently under construction, is designed to produce a high flux of high energy neutrons for irradiation effects experiments on fusion reactor materials. Characterization of the flux-fluence-spectrum in this rapidly varying neutron field requires adaptation and extension of currently available dosimetry techniques. This characterization will be carried out by a combination of active, passive, and calculational dosimetry. The goal is to provide the experimenter with accurate neutron flux-fluence-spectra at all positions in the test cell. Plans have been completed for a number of experimental dosimetry stations and provision for these facilities has been incorporated into the FMIT design. Overall needs of the FMIT irradiation damage program delineate goal accuracies for dosimetry that, in turn, create new requirements for high energy neutron cross section data. Recommendations based on these needs have been derived for required cross section data and accuracies.

Gold, R.; McElroy, W.N.; Lippincott, E.P.; Mann, F.M.; Oberg, D.L.; Roberts, J.H.; Ruddy, F.H.

1980-05-02

161

Dosimetry of [??Ga]-labeled compounds.  

PubMed

This review compiles and analyzes the available dosimetry data of [(68)Ga] labeled compounds. Dosimetry data are given for [(68)Ga]DOTA-NOC, TOC, TATE, and NODAGA-RGDyK. The number of PET-scans with [(68)Ga]DOTA-compounds for imaging neuroendocrine tumors is increasing because [(68)Ga] has a higher affinity to somatostatin receptors (SSTR) in comparison to comparable [(111)In]-compounds. In addition, the better image resolution of the PET images provides improved diagnostics. Despite its widespread use literature on dosimetry of [(68)Ga]-labeled radiopharmaceuticals is sparse. In some cases the description of the underlying methodology is missing or human data are gained from the extrapolation of animal experiments. More and better documented dosimetry data will further promote the use of these promising new agents. PMID:22884623

Eberlein, U; Lassmann, M

2013-06-01

162

Report on high energy neutron dosimetry workshop  

SciTech Connect

The workshop was called to assess the performance of neutron dosimetry per the responses from ten DOE accelerator facilities to an Office of Energy Research questionnaire regarding implementation of a personnel dosimetry requirement in DRAFT DOE 5480.ACC, Safety of Accelerator Facilities''. The goals of the workshop were to assess the state of dosimetry at high energy accelerators and if such dosimetry requires improvement, to reach consensus on how to proceed with such improvements. There were 22 attendees, from DOE Programs and contract facilities, DOE, Office of Energy Research (ER), Office of Environmental Safety and Health (EH), Office of Fusion Energy, and the DOE high energy accelerator facilities. A list of attendees and the meeting agenda are attached. Copies of the presentations are also attached.

Alvar, K.R.; Gavron, A.

1993-01-27

163

Report on high energy neutron dosimetry workshop  

SciTech Connect

The workshop was called to assess the performance of neutron dosimetry per the responses from ten DOE accelerator facilities to an Office of Energy Research questionnaire regarding implementation of a personnel dosimetry requirement in DRAFT DOE 5480.ACC, ``Safety of Accelerator Facilities``. The goals of the workshop were to assess the state of dosimetry at high energy accelerators and if such dosimetry requires improvement, to reach consensus on how to proceed with such improvements. There were 22 attendees, from DOE Programs and contract facilities, DOE, Office of Energy Research (ER), Office of Environmental Safety and Health (EH), Office of Fusion Energy, and the DOE high energy accelerator facilities. A list of attendees and the meeting agenda are attached. Copies of the presentations are also attached.

Alvar, K.R.; Gavron, A.

1993-01-27

164

INTERSPECIES DOSIMETRY MODELS FOR PULMONARY PHARMACOLOGY  

EPA Science Inventory

Interspecies Dosimetry Models for Pulmonary Pharmacology Ted B. Martonen, Jeffry D. Schroeter, and John S. Fleming Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangl...

165

Transdermal delivery of paeonol using cubic gel and microemulsion gel  

PubMed Central

Background The aim of this study was to develop new systems for transdermal delivery of paeonol, in particular microemulsion gel and cubic gel formulations. Methods Various microemulsion vehicles were prepared using isopropyl myristate as an oil phase, polyoxyethylated castor oil (Cremophor® EL) as a surfactant, and polyethylene glycol 400 as a cosurfactant. In the optimum microemulsion gel formulation, carbomer 940 was selected as the gel matrix, and consisted of 1% paeonol, 4% isopropyl myristate, 28% Cremophor EL/polyethylene glycol 400 (1:1), and 67% water. The cubic gel was prepared containing 3% paeonol, 30% water, and 67% glyceryl monooleate. Results A skin permeability test using excised rat skins indicated that both the cubic gel and microemulsion gel formulations had higher permeability than did the paeonol solution. An in vivo pharmacokinetic study done in rats showed that the relative bioavailability of the cubic gel and microemulsion gel was enhanced by about 1.51-fold and 1.28-fold, respectively, compared with orally administered paeonol suspension. Conclusion Both the cubic gel and microemulsion gel formulations are promising delivery systems to enhance the skin permeability of paeonol, in particular the cubic gel. PMID:21904450

Luo, Maofu; Shen, Qi; Chen, Jinjin

2011-01-01

166

Narrow stereotactic beam profile measurements using N-vinylpyrrolidone based polymer gels and magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

In this work, polymer gel-MRI dosimetry (using VIPAR gels), radiographic film and a PinPoint ion chamber were used for profile measurements of 6 MV x-ray stereotactic beams of 5 and 10 mm diameter. The VIPAR gel-MRI method exhibited a linear dose response up to 32 Gy. VIPAR gels were found to resolve the penumbra region quite accurately, provided that the in-plane image resolution of the related T2-map is adequate (?0.53 mm). T2-map slice thickness had no significant effect on beam profile data. VIPAR measurements performed with a spatial resolution of 0.13 mm provided penumbra widths (80%-20% distance) of 1.34 and 1.70 mm for the 5 and 10 mm cones respectively. These widths were found to be significantly smaller than those obtained with the film (2.23 mm for the 5 mm cone, 2.45 mm for the 10 mm cone) and PinPoint (2.25 mm for the 5 mm cone, 2.52 mm for the 10 mm cone) methods. Regarding relative depth dose measurements, good correlation between VIPAR gel and PinPoint data was observed. In conclusion, polymer gel-MRI dosimetry can provide relatively accurate profile data for very small beams used in stereotactic radiosurgery since it can overcome, to some extent, the problems related to the finite size of conventional detectors.

Pappas, E.; Seimenis, I.; Angelopoulos, A.; Georgolopoulou, P.; Kamariotaki-Paparigopoulou, M.; Maris, T.; Sakelliou, L.; Sandilos, P.; Vlachos, L.

2001-03-01

167

In vivo dosimetry in brachytherapy  

SciTech Connect

In vivo dosimetry (IVD) has been used in brachytherapy (BT) for decades with a number of different detectors and measurement technologies. However, IVD in BT has been subject to certain difficulties and complexities, in particular due to challenges of the high-gradient BT dose distribution and the large range of dose and dose rate. Due to these challenges, the sensitivity and specificity toward error detection has been limited, and IVD has mainly been restricted to detection of gross errors. Given these factors, routine use of IVD is currently limited in many departments. Although the impact of potential errors may be detrimental since treatments are typically administered in large fractions and with high-gradient-dose-distributions, BT is usually delivered without independent verification of the treatment delivery. This Vision 20/20 paper encourages improvements within BT safety by developments of IVD into an effective method of independent treatment verification.

Tanderup, Kari [Department of Oncology, Aarhus University Hospital, Aarhus 8000 (Denmark); Department of Clinical Medicine, Aarhus University, Aarhus 8000 (Denmark); Beddar, Sam [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Andersen, Claus E.; Kertzscher, Gustavo [Center of Nuclear Technologies, Technical University of Denmark, Roskilde 4000 (Denmark); Cygler, Joanna E. [Department of Physics, Ottawa Hospital Cancer Centre, Ottawa, Ontario K1H 8L6 (Canada)

2013-07-15

168

In vivo dosimetry in brachytherapy.  

PubMed

In vivo dosimetry (IVD) has been used in brachytherapy (BT) for decades with a number of different detectors and measurement technologies. However, IVD in BT has been subject to certain difficulties and complexities, in particular due to challenges of the high-gradient BT dose distribution and the large range of dose and dose rate. Due to these challenges, the sensitivity and specificity toward error detection has been limited, and IVD has mainly been restricted to detection of gross errors. Given these factors, routine use of IVD is currently limited in many departments. Although the impact of potential errors may be detrimental since treatments are typically administered in large fractions and with high-gradient-dose-distributions, BT is usually delivered without independent verification of the treatment delivery. This Vision 20/20 paper encourages improvements within BT safety by developments of IVD into an effective method of independent treatment verification. PMID:23822403

Tanderup, Kari; Beddar, Sam; Andersen, Claus E; Kertzscher, Gustavo; Cygler, Joanna E

2013-07-01

169

Quantum Data Fitting  

E-print Network

We provide a new quantum algorithm that efficiently determines the quality of a least-squares fit over an exponentially large data set by building upon an algorithm for solving systems of linear equations efficiently (Harrow et al., Phys. Rev. Lett. {\\bf 103}, 150502 (2009)). In many cases, our algorithm can also efficiently find a concise function that approximates the data to be fitted and bound the approximation error. In cases where the input data is a pure quantum state, the algorithm can be used to provide an efficient parametric estimation of the quantum state and therefore can be applied as an alternative to full quantum state tomography given a fault tolerant quantum computer.

Nathan Wiebe; Daniel Braun; Seth Lloyd

2012-04-24

170

Health/Fitness Instructor's Handbook.  

ERIC Educational Resources Information Center

This book identifies the components of physical fitness that are related to positive health as distinct from the simple performance of specific motor tasks. The positive health concept is expanded to further clarify the relationship of physical fitness to total fitness. The disciplinary knowledge base that is essential for fitness professionals is…

Howley, Edward T.; Franks, B. Don

171

Fitting of protective football equipment  

Microsoft Academic Search

As no other guide was found to illustrate and describe protec tive equipment and its fitting, we have prepared this treatise. Properly fitted protective equipment for football is a must to prevent injury from occurring. Many injuries result from im properly fitted equipment. The helmet and shoulder pads are the most important pieces of equipment that require proper fit. Adequate

Joe Gieck; Frank C. McCue

1980-01-01

172

Fitting the phenomenological MSSM  

SciTech Connect

We perform a global Bayesian fit of the phenomenological minimal supersymmetric standard model (pMSSM) to current indirect collider and dark matter data. The pMSSM contains the most relevant 25 weak-scale MSSM parameters, which are simultaneously fit using 'nested sampling' Monte Carlo techniques in more than 15 years of CPU time. We calculate the Bayesian evidence for the pMSSM and constrain its parameters and observables in the context of two widely different, but reasonable, priors to determine which inferences are robust. We make inferences about sparticle masses, the sign of the {mu} parameter, the amount of fine-tuning, dark matter properties, and the prospects for direct dark matter detection without assuming a restrictive high-scale supersymmetry breaking model. We find the inferred lightest CP-even Higgs boson mass as an example of an approximately prior-independent observable. This analysis constitutes the first statistically convergent pMSSM global fit to all current data.

AbdusSalam, Shehu S.; Allanach, Benjamin C. [DAMTP, Center for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Quevedo, Fernando [DAMTP, Center for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); CERN, PH-TH, CH-1211, Geneva 23 (Switzerland); Feroz, Farhan; Hobson, Mike [Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2010-05-01

173

Dose verification of single shot gamma knife applications using VIPAR polymer gel and MRI.  

PubMed

This work describes an experimental procedure with potential to assess the overall accuracy associated with gamma knife clinical applications, from patient imaging and dosimetry planning to patient positioning and dose delivery using the automated positioning system of a Leksell Gamma Knife model C. The VIPAR polymer gel-MRI dosimetry method is employed due to its inherent three-dimensional feature and linear dose response over the range of gamma knife applications. Different polymer gel vials were irradiated with single shot gamma knife treatment plans using each of the four available collimator helmets to deliver a maximum dose of 30 Gy. Percentage relative dose results are presented not only in the form of one-dimensional profiles but also planar isocontours and isosurfaces in three dimensions. Experimental results are compared with corresponding Gammaplan treatment planning system calculations as well as acceptance test radiochromic film measurements. A good agreement, within the experimental uncertainty, is observed between measured and expected dose distributions. This experimental uncertainty is of the order of one imaging pixel in the MRI gel readout session (<1 mm) and allows for the verification of single shot gamma knife applications in terms of acceptance specifications for precision in beam alignment and accuracy. Averaging net R(2) results in the dose plateau of the 4 mm and 18 mm collimator irradiated gel vials, which were MR scanned in the same session, provides a crude estimate of the 4 mm output factor which agrees within errors with the default value of 0.870. PMID:15798319

Karaiskos, P; Petrokokkinos, L; Tatsis, E; Angelopoulos, A; Baras, P; Kozicki, M; Papagiannis, P; Rosiak, J M; Sakelliou, L; Sandilos, P; Vlachos, L

2005-03-21

174

Dose verification of single shot gamma knife applications using VIPAR polymer gel and MRI  

NASA Astrophysics Data System (ADS)

This work describes an experimental procedure with potential to assess the overall accuracy associated with gamma knife clinical applications, from patient imaging and dosimetry planning to patient positioning and dose delivery using the automated positioning system of a Leksell Gamma Knife model C. The VIPAR polymer gel-MRI dosimetry method is employed due to its inherent three-dimensional feature and linear dose response over the range of gamma knife applications. Different polymer gel vials were irradiated with single shot gamma knife treatment plans using each of the four available collimator helmets to deliver a maximum dose of 30 Gy. Percentage relative dose results are presented not only in the form of one-dimensional profiles but also planar isocontours and isosurfaces in three dimensions. Experimental results are compared with corresponding Gammaplan treatment planning system calculations as well as acceptance test radiochromic film measurements. A good agreement, within the experimental uncertainty, is observed between measured and expected dose distributions. This experimental uncertainty is of the order of one imaging pixel in the MRI gel readout session (<1 mm) and allows for the verification of single shot gamma knife applications in terms of acceptance specifications for precision in beam alignment and accuracy. Averaging net R2 results in the dose plateau of the 4 mm and 18 mm collimator irradiated gel vials, which were MR scanned in the same session, provides a crude estimate of the 4 mm output factor which agrees within errors with the default value of 0.870.

Karaiskos, P.; Petrokokkinos, L.; Tatsis, E.; Angelopoulos, A.; Baras, P.; Kozicki, M.; Papagiannis, P.; Rosiak, J. M.; Sakelliou, L.; Sandilos, P.; Vlachos, L.

2005-03-01

175

A prototype fan-beam optical CT scanner for 3D dosimetry  

SciTech Connect

Purpose: The objective of this work is to introduce a prototype fan-beam optical computed tomography scanner for three-dimensional (3D) radiation dosimetry. Methods: Two techniques of fan-beam creation were evaluated: a helium-neon laser (HeNe, {lambda} = 543 nm) with line-generating lens, and a laser diode module (LDM, {lambda} = 635 nm) with line-creating head module. Two physical collimator designs were assessed: a single-slot collimator and a multihole collimator. Optimal collimator depth was determined by observing the signal of a single photodiode with varying collimator depths. A method of extending the dynamic range of the system is presented. Two sample types were used for evaluations: nondosimetric absorbent solutions and irradiated polymer gel dosimeters, each housed in 1 liter cylindrical plastic flasks. Imaging protocol investigations were performed to address ring artefacts and image noise. Two image artefact removal techniques were performed in sinogram space. Collimator efficacy was evaluated by imaging highly opaque samples of scatter-based and absorption-based solutions. A noise-based flask registration technique was developed. Two protocols for gel manufacture were examined. Results: The LDM proved advantageous over the HeNe laser due to its reduced noise. Also, the LDM uses a wavelength more suitable for the PRESAGE{sup TM} dosimeter. Collimator depth of 1.5 cm was found to be an optimal balance between scatter rejection, signal strength, and manufacture ease. The multihole collimator is capable of maintaining accurate scatter-rejection to high levels of opacity with scatter-based solutions (T < 0.015%). Imaging protocol investigations support the need for preirradiation and postirradiation scanning to reduce reflection-based ring artefacts and to accommodate flask imperfections and gel inhomogeneities. Artefact removal techniques in sinogram space eliminate streaking artefacts and reduce ring artefacts of up to {approx}40% in magnitude. The flask registration technique was shown to achieve submillimetre and subdegree placement accuracy. Dosimetry protocol investigations emphasize the need to allow gel dosimeters to cool gradually and to be scanned while at room temperature. Preliminary tests show that considerable noise reduction can be achieved with sinogram filtering and by binning image pixels into more clinically relevant grid sizes. Conclusions: This paper describes a new optical CT scanner for 3D radiation dosimetry. Tests demonstrate that it is capable of imaging both absorption-based and scatter-based samples of high opacities. Imaging protocol and gel dosimeter manufacture techniques have been adapted to produce optimal reconstruction results. These optimal results will require suitable filtering and binning techniques for noise reduction purposes.

Campbell, Warren G.; Rudko, D. A.; Braam, Nicolas A.; Jirasek, Andrew [University of Victoria, Victoria, British Columbia V8P 5C2 (Canada); Wells, Derek M. [British Columbia Cancer Agency, Vancouver Island Centre, Victoria, British Columbia V8R 6V5 (Canada)

2013-06-15

176

Gastrointestinal Mucus Gel Barrier  

Microsoft Academic Search

A family of glycoproteins, known as gel-forming mucins, endow gastrointestinal mucus with its characteristic viscoelastic\\u000a and biological properties. In the mucus, these large oligomeric glycoproteins are organized into entangled networks that occasionally\\u000a can be stabilized by non-covalent interactions as in the stomach lumen. This network is a formidable chemical and physical\\u000a barrier that not only protects the underlying epithelia but

Juan Perez-Vilar

177

Characterizing matrix remodeling in collagen gels using optical coherence tomography  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) has shown promise at non-destructively characterizing engineered tissues such as collagen gels. However, as the collagen gels develop, the OCT images lose contrast of structures as the gels develop, making visual assessment difficult. Our group proposed quantitatively characterizing these gels by fitting the optical properties from the OCT signals. In this paper, we imaged collagen gels seeded with smooth muscle cells (SMCs) over a 5-day period and used the data to measure their optical properties. Our results showed that over time, the reflectivity of the samples increased 10-fold, corresponding to a decrease in anisotropy factor g, without much change in the scattering coefficient ?s. Overall, the optical properties appeared to be dominated by scattering from the collagen matrix, not the cells. However, SMCs remodeled the collagen matrix, and this collagen remodeling by the cells is what causes the observed changes in optical properties. Moreover, the data showed that the optical properties were sensitive to the activity of matrix metalloproteinases (MMPs), enzymes that break down local collagen fibrils into smaller fragments. Blocking MMPs in the SMC gels greatly impeded both the remodeling process and change in optical properties at day 5. Treating day 1 acellular gels with MMP-8 for 3 hr managed to partially reproduce the remodeling observed in SMC gels at day 5. Altogether, we conclude that matrix remodeling in general, and MMPs specifically, greatly affect the local optical properties of the sample, and OCT is a unique tool that can assess MMP activity in collagen gels both non-destructively and label free.

Levitz, David; Hinds, Monica T.; Hanson, Stephen R.; Jacques, Steven L.

2010-02-01

178

Radiation dosimetry and medical physics calculations using MCNP 5  

E-print Network

Six radiation dosimetry and medical physics problems were analyzed using a beta version of MCNP 5 as part of an international intercomparison of radiation dosimetry computer codes, sponsored by the European Commission committee on the quality...

Redd, Randall Alex

2004-09-30

179

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

E-print Network

207 Radiation Protection Dosimetry Vol. 100, Nos 1­4, pp. 207­209 (2002) Nuclear Technology of these crystals to solid state dosimetry was also investigated. EXPERIMENTAL TECHNIQUE A series of CsGd2F7 single

Chen, Reuven

180

Ocular tolerance of sertaconazole gel.  

PubMed

The in vitro and in vivo tolerance of sertaconazole gel, a new topical azole antifungal, was studied. Ketoconazole gel (Panfungol) was used as a reference substance. The methods applied for tolerance assessment were the bovine corneal opacity and permeability test for the in vitro assay and a modified Draize test for the in vivo assay. The results obtained show that both substances can be classified as slightly irritant and with acceptable tolerance. However, unlike ketoconazole gel, sertaconazole gel did not cause a positive lesion index in vivo. Ketoconazole was 5.25 times more irritant in vitro than sertaconazole gel, whose effect was similar to that of saline solution. Consequently, the negligible irritant effect of sertaconazole gel on a type of epithelium that is extremely sensitive, i.e. the cornea, confirms the good tolerance of this new antifungal gel on other structures such as the skin and mucous membranes. PMID:8786760

Romero, A; Grau, M T; Villamayor, F; Zapatero, J; Mayordomo, L; Tortajada, A; Sacristán, A; Ortiz, J A

1996-01-01

181

In aqua vivo EPID dosimetry  

SciTech Connect

Purpose: At the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital in vivo dosimetry using an electronic portal imaging device (EPID) has been implemented for almost all high-energy photon treatments of cancer with curative intent. Lung cancer treatments were initially excluded, because the original back-projection dose-reconstruction algorithm uses water-based scatter-correction kernels and therefore does not account for tissue inhomogeneities accurately. The aim of this study was to test a new method, in aqua vivo EPID dosimetry, for fast dose verification of lung cancer irradiations during actual patient treatment. Methods: The key feature of our method is the dose reconstruction in the patient from EPID images, obtained during the actual treatment, whereby the images have been converted to a situation as if the patient consisted entirely of water; hence, the method is termed in aqua vivo. This is done by multiplying the measured in vivo EPID image with the ratio of two digitally reconstructed transmission images for the unit-density and inhomogeneous tissue situation. For dose verification, a comparison is made with the calculated dose distribution with the inhomogeneity correction switched off. IMRT treatment verification is performed for each beam in 2D using a 2D {gamma} evaluation, while for the verification of volumetric-modulated arc therapy (VMAT) treatments in 3D a 3D {gamma} evaluation is applied using the same parameters (3%, 3 mm). The method was tested using two inhomogeneous phantoms simulating a tumor in lung and measuring its sensitivity for patient positioning errors. Subsequently five IMRT and five VMAT clinical lung cancer treatments were investigated, using both the conventional back-projection algorithm and the in aqua vivo method. The verification results of the in aqua vivo method were statistically analyzed for 751 lung cancer patients treated with IMRT and 50 lung cancer patients treated with VMAT. Results: The improvements by applying the in aqua vivo approach are considerable. The percentage of {gamma} values {<=}1 increased on average from 66.2% to 93.1% and from 43.6% to 97.5% for the IMRT and VMAT cases, respectively. The corresponding mean {gamma} value decreased from 0.99 to 0.43 for the IMRT cases and from 1.71 to 0.40 for the VMAT cases, which is similar to the accepted clinical values for the verification of IMRT treatments of prostate, rectum, and head-and-neck cancers. The deviation between the reconstructed and planned dose at the isocenter diminished on average from 5.3% to 0.5% for the VMAT patients and was almost the same, within 1%, for the IMRT cases. The in aqua vivo verification results for IMRT and VMAT treatments of a large group of patients had a mean {gamma} of approximately 0.5, a percentage of {gamma} values {<=}1 larger than 89%, and a difference of the isocenter dose value less than 1%. Conclusions: With the in aqua vivo approach for the verification of lung cancer treatments (IMRT and VMAT), we can achieve results with the same accuracy as obtained during in vivo EPID dosimetry of sites without large inhomogeneities.

Wendling, Markus; McDermott, Leah N.; Mans, Anton; Olaciregui-Ruiz, Igor; Pecharroman-Gallego, Raul; Sonke, Jan-Jakob; Stroom, Joep; Herk, Marcel J.; Mijnheer, Ben van [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands)

2012-01-15

182

High resolution MR based polymer dosimetry versus film densitometry: a systematic study based on the modulation transfer function approach.  

PubMed

Precise methods of modem radiation therapy such as intensity modulated radiotherapy (IMRT), brachytherapy (BT) and high LET irradiation allow for high dose localization in volumes of a few mm3. However, most dosimetry methods-ionization chambers, TLD arrangements or silicon detectors, for example-are not capable of detecting sub-mm dose variations or do not allow for simple dose imaging. Magnetic resonance based polymer dosimetry (MRPD) appears to be well suited to three-dimensional high resolution relative dosimetry but the spatial resolution based on a systematic modulation transfer function (MTF) approach has not yet been investigated. We offer a theoretical construct for addressing the spatial resolution in different dose imaging systems, i.e. the dose modulation transfer function (DMTF) approach, an experimental realization of this concept with a phantom and quantitative comparisons between two dosimetric systems: polymer gel and film dosimetry. Polymer gel samples were irradiated by Co-60 photons through an absorber grid which is characterized by periodic structures of different spatial period (a), the smallest one at width of a/2 = 280 microm. The modulation in dose under the grid is visualized via calibrated, high resolution, parameter-selective (T2) and dose images based on multi-echo MR imaging. The DMTF is obtained from the modulation depth of the spin-spin relaxation time (T2) after calibration. Voxel sizes below 0.04 mm3 could be achieved, which are significantly smaller than those reported in MR based dose imaging on polymer gels elsewhere, using a powerful gradient system and a highly sensitive small birdcage resonator on a whole-body 3T MR scanner. Dose modulations at 22% of maximum dose amplitude could be observed at about 2 line pairs per mm. The polymer DMTF results are compared to those of a typical clinical film-scanner system. This study demonstrates that MR based gel dosimetry at 200 microm pixel resolution might even be superior, with reference to relative spatial resolution, to the results of a standard film-scanner system offering a nominal scan resolution of 200 microm. PMID:15470925

Berg, A; Pernkopf, M; Waldhäusl, C; Schmidt, W; Moser, E

2004-09-01

183

Technical Basis Document for PFP Area Monitoring Dosimetry Program  

SciTech Connect

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

COOPER, J.R.

2000-04-17

184

Personnel neutron dosimetry at Department of Energy facilities  

SciTech Connect

This study assesses the state of personnel neutron dosimetry at DOE facilities. A survey of the personnel dosimetry systems in use at major DOE facilities was conducted, a literature search was made to determine recent advances in neutron dosimetry, and several dosimetry experts were interviewed. It was concluded that personnel neutron dosimeters do not meet current needs and that serious problems exist now and will increase in the future if neutron quality factors are increased and/or dose limits are lowered.

Brackenbush, L.W.; Endres, G.W.R.; Selby, J.M.; Vallario, E.J.

1980-08-01

185

Breast dosimetry in clinical mammography  

NASA Astrophysics Data System (ADS)

The objective of this study was show that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. In the study, AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The protocol proposes the use of a fiber-optic coupled (FOCD) or Metal Oxide Semiconductor Field Effect Transistor (MOSFET) dosimeter to measure the entrance skin exposure at the time of the mammogram without interfering with diagnostic information of the mammogram. The study showed that FOCD had sensitivity with less than 7% energy dependence, linear in all tube current-time product stations, and was reproducible within 2%. FOCD was superior to MOSFET dosimeter in sensitivity, reusability, and reproducibility. The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. In addition, the study population anthropometric measurements enabled the development of analytical equations to calculate the whole breast area, estimate for the skin layer thickness and optimal location for automatic exposure control ionization chamber. The clinical dosimetry protocol developed in this study can reliably predict the AGD imparted to an individual patient during a routine screening mammogram.

Benevides, Luis Alberto Do Rego

186

FIT ITALLT3 The World of Food & Fitness  

E-print Network

Foods Fund. Inc. for financial assistance in helping to make possible the publication$3.50 FIT ITALLT3 IOGETHER The World of Food & Fitness \\ :.. '? 41/ % Attit; P'caJct FN.U13 Oregon State' Extension UNIVERSITY Service 4-H 9318 Reprinted October 2005 #12;FIT ITALLUNIT3 The World of Food

Tullos, Desiree

187

Request for Dosimetry Form Worker Information (Please PRINT /fill legibly)  

E-print Network

Request for Dosimetry Form Worker Information (Please PRINT /fill legibly) Last Name First Name You must obtain the approval holder's signature to be issued dosimetry. If the approval holder to attach NRC Form 5 /dosimetry report for the past one year from the most recent institution) I hereby

Berdichevsky, Victor

188

Original article Whole-body biodistribution and radiation dosimetry  

E-print Network

Original article Whole-body biodistribution and radiation dosimetry estimates for the PET dopamine Communications 2004, 25:737­742 Keywords: 18 F-FECNT, dopamine transporter, dosimetry, whole-body bio assessment of the resulting radiation exposure to organs of the body. Radiation dosimetry estimates were

Shen, Jun

189

THE FERNALD DOSIMETRY RECONSTRUCTION Task 1: Identification of Release Points  

E-print Network

THE FERNALD DOSIMETRY RECONSTRUCTION PROJECT Task 1: Identification of Release Points-l January 22, 1991 #12;THE FERNALD DOSIMETRY RECONSTRUCTION PROJECT Task 1: Identification of Release Points the standard in radiation health" #12;2 The Fernald Dosimetry Reconstruction Project Task 1 Report

190

TECHNICAL APPENDICES Appendix A: Summary of the Fernald Dosimetry Reconstruction  

E-print Network

TECHNICAL APPENDICES Appendix A: Summary of the Fernald Dosimetry Reconstruction Project's Dose Dosimetry Reconstruction Project's Dose and Risk Estimates. Appendices - 2 #12;I. Summary of Fernald Dose Reconstruction Project's Dose and Risk Estimates A. THE FERNALD DOSIMETRY RECONSTRUCTION PROJECT The Fernald

191

Radiation Protection Dosimetry Vol. 100, Nos 14, pp. 7174 (2002)  

E-print Network

71 Radiation Protection Dosimetry Vol. 100, Nos 1­4, pp. 71­74 (2002) Nuclear Technology Publishing (OSL) has become a very important method for radiation dosimetry. In many laboratories, it is replacing of this method for dosimetry and dating is basically dependent on this premise. There are, however, some reports

Chen, Reuven

192

ORIGINAL ARTICLE Biodistribution and dosimetry in humans of two inverse  

E-print Network

ORIGINAL ARTICLE Biodistribution and dosimetry in humans of two inverse agonists to image F-FMPEP-d2. Here we describe the biodistribution and dosimetry estimates for these two radioligands-MePPEP. 18 F-FMPEP-d2 . Dosimetry. PET Introduction The cannabinoid subtype 1 (CB1) receptor is coupled to G

Shen, Jun

193

A Nonparametric Bayesian Modeling Approach for Cytogenetic Dosimetry  

E-print Network

A Nonparametric Bayesian Modeling Approach for Cytogenetic Dosimetry Athanasios Kottas Institute. In cytogenetic dosimetry, samples of cell cultures are exposed to a range of doses of a given agent. In each of micronuclei per cell. 1 Introduction Cytogenetic dosimetry is the particular area of dose­response modeling

West, Mike

194

1. Introduction Alanine-based ionizing radiation dosimetry is firmly  

E-print Network

1. Introduction Alanine-based ionizing radiation dosimetry is firmly woven into the fabric of high-dose radiation metrology. Because of its superior attributes, alanine dosimetry was recognized at an early stage of use at the NMI level, confidence in the system has grown such that ala- nine dosimetry use is growing

195

A Nonparametric Bayesian Modeling Approach for Cytogenetic Dosimetry  

E-print Network

A Nonparametric Bayesian Modeling Approach for Cytogenetic Dosimetry Athanasios Kottas Institute. In cytogenetic dosimetry, samples of cell cultures are exposed to a range of doses of a given agent. In each of micronuclei per cell. 1 Introduction Cytogenetic dosimetry is the particular area of dose-response modeling

West, Mike

196

Probabilistic methods applied to 2D electromagnetic numerical dosimetry  

E-print Network

Probabilistic methods applied to 2D electromagnetic numerical dosimetry D. Voyer F. Musy L. Nicolas dosimetry problems in order to take into account the variability of the input parameters. Methodology Numerical dosimetry, electromagnetism, stochastic method, poly- nomial chaos, sparse grid. Paper type

Paris-Sud XI, Université de

197

THE FERNALD DOSIMETRY RECONSTRUCTION PROJECT Environmental Pathways -Models and Validation  

E-print Network

~\\ ( f C r L THE FERNALD DOSIMETRY RECONSTRUCTION PROJECT Task 4 Environmental Pathways - Models . . . . . . 8 RADIONUCLIDES RELEASED FROM THE FMPC 9 MODELS OF ENVIRONMENTAL TRANSPORT AND DOSIMETRY 10 . . . . . . . . . . . . . . . . . . . . 30 Transport and Dosimetry for Radon and Radon Daughters 30 Direct Exposures from Gamma Radiation

198

School of Medical Dosimetry A JRCERT Accredited Program  

E-print Network

- 1 - 1 School of Medical Dosimetry A JRCERT Accredited Program Program Handbook #12;2 Table notice. #12;3 The Profession Medical dosimetry is the sub-specialty of Radiation Oncology that focuses calculations. #12;4 Mission "To provide world class education and training in medical dosimetry and provide

Weber, David J.

199

Biologically weighted personal UV dosimetry.  

PubMed

People are exposed to natural or artificial UV radiation in different ways; unintentionally or intentionally, at their workplace on their spare time. To quantify the amount of individual UV exposure, a personal dosimetry is necessary. In research, polysulphone film (PSF) dosimeters are the most frequently used personal UV dosimeters. We use calculated weighting factors in the measurement processing of polysulphone film dosimeters. The special weighting factor transforms the dosimeter reading from an equivalent UV dose to the biologically effective UV dose. The factor depends on the investigated problem (action spectrum of the photobiological effect and spectral distribution of the incident UV source), the calibration of PSF was carried out once by a monochromatic radiation (gamma = 295 nm). The equivalent dose readings are available from this calibration curve for any investigated question. A presented result of this method is the seasonal measurement of erythemally effective UV exposure by ambient solar radiation, and the individual exposure level in a "normal" person concerning UV exposure and also in groups with the risk of a lack of sunshine. Further applications are occupational measurements of the risk of health damage by UV radiation (with respect to the limit of the maximum permissible 8 h-exposure according to IRPA/INIRC-guidelines). We controlled the extent of UV exposure in workers in the area of arc welding workplaces. The biological weighting of PSF readings simplifies a routine use of PSF in personal UV monitoring to investigators without the expending special measurement technology (e.g. spectroradiometer). PMID:8988614

Knuschke, P; Barth, J

1996-10-01

200

Being fit in pregnancy.  

PubMed

There is a substantial body of evidence to suggest that exercise during pregnancy is not only safe but beneficial, yet many women remain unsure about what exercise is appropriate or indeed whether it is safe to exercise at all, opting instead for inactivity. The purpose of this article is to explore the benefits of maintaining or improving fitness during pregnancy. It explores some of the more appropriate and accessible exercise options to help encourage women to achieve the recommended level of 30 minutes of physical activity a day (National Institute of Health and Care excellence (NICE) 2010). The article also recognises the need for accessible information regarding exercise and highlights some of the resources that pregnant women might find useful. PMID:24600825

Hazeldean, Deborah

2014-02-01

201

Methodology Review: Evaluating Person Fit.  

ERIC Educational Resources Information Center

Reviews person-fit methods based on classical test theory and item response theory and the methods investigating particular types of response behavior on tests. Discusses similarities and differences among person-fit methods and their advantages and disadvantages. The usefulness of person-fit statistics for improving measurement depends on the…

Meijer, Rob R.; Sijtsma, Klaas

2001-01-01

202

Florida's Fit to Achieve Program.  

ERIC Educational Resources Information Center

Describes Florida's "Fit to Achieve," a cardiovascular fitness education program for elementary students. Children are taught responsibility for their own cardiovascular fitness through proper exercise, personal exercise habits, and regular aerobic exercise. The program stresses collaborative effort between physical educators and classroom…

Sander, Allan N.; And Others

1993-01-01

203

Designing Fitness Trails for Seniors.  

ERIC Educational Resources Information Center

Fitness trails for senior adults are being developed in retirement communities and community parks nationwide to enhance total fitness through activities that build cardiovascular endurance, flexibility, strength, and balance. Recreation planners must create fitness trails that are interesting, enjoyable, safe, and appropriate for the senior…

Hall, Kenneth B.

1991-01-01

204

Survey of international personnel radiation dosimetry programs  

SciTech Connect

In September of 1983, a mail survey was conducted to determine the status of external personnel gamma and neutron radiation dosimetry programs at international agencies. A total of 130 agencies participated in this study including military, regulatory, university, hospital, laboratory, and utility facilities. Information concerning basic dosimeter types, calibration sources, calibration phantoms, corrections to dosimeter responses, evaluating agencies, dose equivalent reporting conventions, ranges of typical or expected dose equivalents, and degree of satisfaction with existing systems was obtained for the gamma and neutron personnel monitoring programs at responding agencies. Results of this survey indicate that to provide the best possible occupational radiation monitoring programs and to improve dosimetry accuracy in performance studies, facility dosimetrists, regulatory and standards agencies, and research laboratories must act within their areas of responsibility to become familiar with their radiation monitoring systems, establish common reporting guidelines and performance standards, and provide opportunities for dosimetry testing and evaluation. 14 references, 10 tables.

Swaja, R.E.

1985-04-01

205

Dosimetry procedures for an industrial irradiation plant  

NASA Astrophysics Data System (ADS)

Accurate and reliable dosimetry procedures constitute a very important part of process control and quality assurance at a radiation processing plant. ?-Dose measurements were made on the GBS 84 irradiator for food and other products on pallets or in containers. Chemical dosimeters wre exposed in the facility under conditions of the typical plant operation. The choice of the dosimeter systems employed was based on the experience in chemical dosimetry gained over several years. Dose uniformity information was obtained in air, spices, bulbs, feeds, cosmetics, plastics and surgical goods. Most products currently irradiated require dose uniformity which can be efficiently provided by pallet or box irradiators like GBS 84. The radiation performance characteristics and some dosimetry procedures are discussed.

Grahn, Ch.

206

Protocol for emergency EPR dosimetry in fingernails.  

PubMed

There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried out on nails freshly sampled and irradiated to 4 and 20 Gy; this protocol gave dose estimates with an error of less than 30%. PMID:18163158

Trompier, F; Kornak, L; Calas, C; Romanyukha, A; Leblanc, B; Mitchell, C A; Swartz, H M; Clairand, I

2007-08-01

207

Advances in medical imaging and related dosimetry  

SciTech Connect

This volume presents a treatise on the physics of the new imaging apparatus used in medicine, namely the x-ray computerized tomography, radio-isotope emission (single photon and positron emission) tomography, nuclear magnetic resonance analysis and imaging, and ultrasound imaging. A chapter is devoted to the radiation problems and health hazards associated with these diagnostic methods. Contents: Radiological Anatomy; Histology and Pathology; Algorithms for Image Reconstruction; Systems and Architectures; Software for Image Enhancement; Hardware for 2D and 3D Imaging; Types of Machines and Associated Radiation Dosimetry; Basic Physics of US, Including Dosimetry; Doppler Diagnostic Methods; Developments, Limitations and Clinical Results; Compton Tomography and Proton Radiography; Clinical Application and Associated Radiation Dosimetry; Advances in MWPC Cameras; NMR Imaging: General Principles and Different Techniques; Tissue Characterization and Tumor Detection; NMR Imaging for Radiotherapy Treatment Planning; Hazard to the Patient from Different Diagnostic Techniques.

Brill, A.; Del Guerra, A.; Mendez, V.; Rindi, A.

1986-01-01

208

High transparent shape memory gel  

NASA Astrophysics Data System (ADS)

Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry. In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals, and the functional groups of thermoreversible Diels-Alder reaction were introduced into soft gels as crosslinkable pendent chains. The functionalization and strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals and thermoreversible pendent chains. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

Gong, Jin; Arai, Masanori; Kabir, M. H.; Makino, Masato; Furukawa, Hidemitsu

2014-03-01

209

Foam and gel decontamination techniques  

SciTech Connect

The Savannah River Site is investigating decontamination technology to improve current decontamination techniques, and thereby reduce radiation exposure to plant personnel, reduce uptake of radioactive material, and improve safety during decontamination and decommissioning activities. When decontamination chemicals are applied as foam and gels, the contact time and cleaning ability of the chemical increases. Foam and gel applicators apply foam or gel that adheres to the surface being decontaminated for periods ranging from fifteen minutes (foam) to infinite contact (gel). This equipment was started up in a cold environment. The desired foam and gel consistency was achieved, operators were trained in its proper maintenance and operation, and the foam and gel were applied to walls, ceilings, and hard to reach surfaces. 17 figs.

McGlynn, J.F.; Rankin, W.N.

1989-01-01

210

Polyoxometalate-based Supramolecular Gel  

PubMed Central

Self-assemblyings of surfactant-encapsulated Wells-Dawson polyoxometalates (SEPs) nanobuilding blocks in butanone and esters yielded supramolecular gels showing thermo and photo responsive properties. The gels can be further polymerized if unsaturated esters were used and subsequently electrospinned into nanowires and non-woven mats. The as-prepared non-woven mats have a Young's modulus as high as 542.55?MPa. It is believed that this supramolecular gel is a good platform for polyoxometalates processing. PMID:23666013

He, Peilei; Xu, Biao; Liu, Huiling; He, Su; Saleem, Faisal; Wang, Xun

2013-01-01

211

Mechanical properties of biological gels  

NASA Astrophysics Data System (ADS)

The rheological properties of biological gels are illustrated by reviewing measurements made on samples containing polymer networks reconstituted from cytoskeletal constitutents. Although these networks are crosslinked by non-covalent interactions which may lead to transient gel behavior, the early-time (rapid) mechanical response of the gels can be characterized by the instantaneous shear modulus. A theory for the latter is described, and used to examine the relationship between the cortical f-actin content and the stiffening of activated polymorphonuclear leukocytes.

Nossal, Ralph

1996-02-01

212

A parameterization method and application in breast tomosynthesis dosimetry  

SciTech Connect

Purpose: To present a parameterization method based on singular value decomposition (SVD), and to provide analytical parameterization of the mean glandular dose (MGD) conversion factors from eight references for evaluating breast tomosynthesis dose in the Mammography Quality Standards Act (MQSA) protocol and in the UK, European, and IAEA dosimetry protocols.Methods: MGD conversion factor is usually listed in lookup tables for the factors such as beam quality, breast thickness, breast glandularity, and projection angle. The authors analyzed multiple sets of MGD conversion factors from the Hologic Selenia Dimensions quality control manual and seven previous papers. Each data set was parameterized using a one- to three-dimensional polynomial function of 2–16 terms. Variable substitution was used to improve accuracy. A least-squares fit was conducted using the SVD.Results: The differences between the originally tabulated MGD conversion factors and the results computed using the parameterization algorithms were (a) 0.08%–0.18% on average and 1.31% maximum for the Selenia Dimensions quality control manual, (b) 0.09%–0.66% on average and 2.97% maximum for the published data by Dance et al. [Phys. Med. Biol. 35, 1211–1219 (1990); ibid. 45, 3225–3240 (2000); ibid. 54, 4361–4372 (2009); ibid. 56, 453–471 (2011)], (c) 0.74%–0.99% on average and 3.94% maximum for the published data by Sechopoulos et al. [Med. Phys. 34, 221–232 (2007); J. Appl. Clin. Med. Phys. 9, 161–171 (2008)], and (d) 0.66%–1.33% on average and 2.72% maximum for the published data by Feng and Sechopoulos [Radiology 263, 35–42 (2012)], excluding one sample in (d) that does not follow the trends in the published data table.Conclusions: A flexible parameterization method is presented in this paper, and was applied to breast tomosynthesis dosimetry. The resultant data offer easy and accurate computations of MGD conversion factors for evaluating mean glandular breast dose in the MQSA protocol and in the UK, European, and IAEA dosimetry protocols. Microsoft Excel™ spreadsheets are provided for the convenience of readers.

Li, Xinhua; Zhang, Da; Liu, Bob [Division of Diagnostic Imaging Physics and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)] [Division of Diagnostic Imaging Physics and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)

2013-09-15

213

Technical basis for internal dosimetry at Hanford  

SciTech Connect

The Hanford Internal Dosimetry Program, administered by Pacific Northwest Laboratory for the US Department of Energy, provides routine bioassay monitoring for employees who are potentially exposed to radionuclides in the workplace. This report presents the technical basis for routine bioassay monitoring and the assessment of internal dose at Hanford. The radionuclides of concern include tritium, corrosion products ({sup 58}Co, {sup 60}Co, {sup 54}Mn, and {sup 59}Fe), strontium, cesium, iodine, europium, uranium, plutonium, and americium,. Sections on each of these radionuclides discuss the sources and characteristics; dosimetry; bioassay measurements and monitoring; dose measurement, assessment, and mitigation and bioassay follow-up treatment. 78 refs., 35 figs., 115 tabs.

Sula, M.J.; Carbaugh, E.H.; Bihl, D.E.

1991-07-01

214

Practical neutron dosimetry at high energies  

SciTech Connect

Dosimetry at high energy particle accelerators is discussed with emphasis on physical measurements which define the radiation environment and provide an immutable basis for the derivation of any quantities subsequently required for risk evaluation. Results of inter-laboratory dosimetric comparisons are reviewed and it is concluded that a well-supported systematic program is needed which would make possible detailed evaluations and inter-comparisons of instruments and techniques in well characterized high energy radiation fields. High-energy dosimetry is so coupled with radiation transport that it is clear their study should proceed concurrently.

McCaslin, J.B.; Thomas, R.H.

1980-10-01

215

Electrically controlled polymeric gel actuators  

DOEpatents

Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots. 11 figures.

Adolf, D.B.; Shahinpoor, M.; Segalman, D.J.; Witkowski, W.R.

1993-10-05

216

Electrically controlled polymeric gel actuators  

DOEpatents

Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.

Adolf, Douglas B. (Albuquerque, NM); Shahinpoor, Mohsen (Albuquerque, NM); Segalman, Daniel J. (Albuquerque, NM); Witkowski, Walter R. (Albuquerque, NM)

1993-01-01

217

Radioluminescence dosimetry by scintillating fiber optics: the open challenges  

NASA Astrophysics Data System (ADS)

In the last decade, the interest in scintillating fiber optics for ionizing radiation monitoring is constantly increasing. Among the fields of possible applications of these sensors, radiation therapy represents a driving force for the research and development of new devices. In fact, the small dimensions of fiber optics based detectors, together with their realtime response, make these systems extremely promising both in quality assurance measurements of intensity modulated radiotherapy beams, and in in-vivo dosimetry. On the other hand, two specific aspects might represent limiting factors: (i) the "stem effect", that is the spurious luminescence originating as a consequence of the irradiation of the light guide, and (ii) the "memory effect", that is the radioluminescence sensitivity increase during prolonged exposition to ionizing radiation, typical of many scintillating materials. These two issues, representing the main challenges to face for the effective use of scintillating fiber as dosimeters in radiotherapy, were studied considering amorphous silica matrices prepared by sol-gel method and doped with europium. The origin of the stem effect was investigated by means of spectral measurements of the doped fibers irradiated with Xrays and electrons of different energies, field sizes and orientations. New approaches for removing the stem effect on the basis of the radioluminescent spectral analysis are presented and discussed. Furthermore, the causes and phenomenology of the memory effect are described, considering also the effect of dose accumulation with different dose rates and energies of ionizing radiation.

Veronese, Ivan; Cantone, Marie Claire; Chiodini, Norberto; De Mattia, Cristina; Fasoli, Mauro; Mones, Eleonora; Vedda, Anna

2013-09-01

218

Electromechanical nonionic gels  

NASA Astrophysics Data System (ADS)

The electrically induced bending of nonionic polyvinyl alcohol gels, bending over 90° within 100 ms, is the fastest motion in the field of electroactuation of polymers. This rapid bending produces initial mechanical vibrations followed by a durable displacement that contrasts highly with the relaxation observed with elastomer- and polyelectrolyte-based actuators. Here, we characterize the bending process using video imaging and laser detecting technology and establish a physical model for the electromechanical conversion, based on our observation of an induced solvent migration. Our results show excellent agreement between the measurements and calculations. This study provides general rules for understanding the electrically induced bending of isotropic dielectrics and may also shed light on nonmuscular biological engines.

Zheng, J.; Xu, C.; Hirai, T.

2008-02-01

219

Difference gel electrophoresis.  

PubMed

DIGE is a protein labelling and separation technique allowing quantitative proteomics of two or more samples by optical fluorescence detection of differentially labelled proteins that are electrophoretically separated on the same gel. DIGE is an alternative to quantitation by MS-based methodologies and can circumvent their analytical limitations in areas such as intact protein analysis, (linear) detection over a wide range of protein abundances and, theoretically, applications where extreme sensitivity is needed. Thus, in quantitative proteomics DIGE is usually complementary to MS-based quantitation and has some distinct advantages. This review describes the basics of DIGE and its unique properties and compares it to MS-based methods in quantitative protein expression analysis. PMID:19003860

Timms, John F; Cramer, Rainer

2008-12-01

220

Distribution effectiveness for space radiation dosimetry  

NASA Technical Reports Server (NTRS)

A simplified risk basis and a theory of hematological response are presented and applied to the problem of dosimetry in the manned space program. Unlike previous studies, the current work incorporates radiation exposure distribution effects into its definition of dose equivalent. The fractional cell lethality model for prediction of hematological response is integral in the analysis.

Wilson, J. W.

1975-01-01

221

DOSIMETRY MODELING OF INHALED TOXIC REACTIVE GASES  

EPA Science Inventory

The report focuses on the physical, chemical and biological processes and factors involved in the absorption of reactive gases. Emphasis is placed on the importance of these factors in developing dosimetry models, special consideration being given to the role of lung fluids and t...

222

2015 Radiation Epidemiology and Dosimetry Course  

Cancer.gov

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

223

Radiochromic film for medical radiation dosimetry  

Microsoft Academic Search

Photon, electron and proton radiations are used extensively for medical purposes in diagnostic and therapeutic procedures. Dosimetry of these radiation sources can be performed with radiochromic films, devices that have the ability to produce a permanent visible colour change upon irradiation. Within the last 10 years, the use of radiochromic films has expanded rapidly in the medical world due to

Martin J Butson; Peter K. N Yu; Tsang Cheung; Peter Metcalfe

2003-01-01

224

BNCT treatments - a human dosimetry evaluation  

SciTech Connect

This paper summarizes a comprehensive calculational study that provides an assessment of the radiation dose received by a glioblastoma multiforme patient treated by boron neutron capture therapy in Japan in mid-1993. This work is an extension of an earlier dosimetry evaluation of a different patient and uses a similar methodology to calculate the radiation doses.

Storr, G.J. [ANSTO, Menai (Australia); Wheeler, F.J. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1994-12-31

225

Applicability of Topaz Composites to Electron Dosimetry  

Microsoft Academic Search

Thermoluminescent dosimetric topaz properties have been investigated and the results have shown that this mineral presents characteristics of a good dosimeter mainly in doses evaluation in radiotherapy with photons beams in radiotherapy. Typical applications of thermoluminescent dosimeters in radiotherapy are: in vivo dosimetry on patients (either as a routine quality assurance procedure or for dose monitoring in special cases); verification

K. S. Bomfim; D. N. Souza

2010-01-01

226

Personnel radiation dosimetry symposium: program and abstracts  

SciTech Connect

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

Not Available

1984-10-01

227

A-bomb survivor dosimetry update  

SciTech Connect

A-bomb survivor data have been generally accepted as applicable. Also, the initial radiations have tended to be accepted as the dominant radiation source for all survivors. There was general acceptance of the essential reliability of both the biological effects data and the causative radiation dose values. There are considerations casting doubt on these acceptances, but very little quantification of th implied uncertainties has been attempted. The exception was A-bomb survivor dosimetry, where free-field kerma values for initial radiations were thought to be accurate to about 30%, and doses to individual survivors were treated as effectively error-free. In 1980, a major challenge to the accepted A-bomb survivor dosimetry was announced, and was quickly followed by a succession of explanations and displays showing the soundness of that challenge. In fact, a complete replacement set of free-field kerma values was provided which was suitable for use in constructing an entire new dosimetry for Hiroshima and Nagasaki. The new values showed many changes greater than the accepted 30% uncertainty. An approximate new dosimetry was indeed constructed, and used to convert existing leukemia cause-and-effect data from the old to the new dose values, by way of assessing the impact. (ERB)

Loewe, W.E.

1982-06-01

228

Development of A-bomb survivor dosimetry  

SciTech Connect

An all important datum in risk assessment is the radiation dose to individual survivors of the bombings in Hiroshima and Nagasaki. The first set of dose estimates for survivors was based on a dosimetry system developed in 1957 by the Oak Ridge National Laboratory (ORNL). These Tentative 1957 Doses (T57D) were later replaced by a more extensive and refined set of Tentative 1965 Doses (T65D). The T65D system of dose estimation for survivors was also developed at ORNL and served as a basis for risk assessment throughout the 1970s. In the late 1970s, it was suggested that there were serious inadequacies with the T65D system, and these inadequacies were the topic of discussion at two symposia held in 1981. In early 1983, joint US- Japan research programs were established to conduct a thorough review of all aspects of the radiation dosimetry for the Hiroshima and Nagasaki A-bomb survivors. A number of important contributions to this review were made by ORNL staff members. The review was completed in 1986 and a new Dosimetry System 1986 (DS86) was adopted for use. This paper discusses the development of the various systems of A-bomb survivor dosimetry, and the status of the current DS86 system as it is being applied in the medical follow-up studies of the A-bomb survivors and their offspring.

Kerr, G.D.

1995-12-31

229

Nanocrystal/sol-gel nanocomposites  

DOEpatents

The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites

Petruska, Melissa A. (Los Alamos, NM); Klimov, Victor L. (Los Alamos, NM)

2012-06-12

230

Nanocrystal/sol-gel nanocomposites  

DOEpatents

The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites.

Petruska, Melissa A. (Los Alamos, NM); Klimov, Victor L. (Los Alamos, NM)

2007-06-05

231

Living bacteria in silica gels  

NASA Astrophysics Data System (ADS)

The encapsulation of enzymes within silica gels has been extensively studied during the past decade for the design of biosensors and bioreactors. Yeast spores and bacteria have also been recently immobilized within silica gels where they retain their enzymatic activity, but the problem of the long-term viability of whole cells in an inorganic matrix has never been fully addressed. It is a real challenge for the development of sol-gel processes. Generic tests have been performed to check the viability of Escherichia coli bacteria in silica gels. Surprisingly, more bacteria remain culturable in the gel than in an aqueous suspension. The metabolic activity of the bacteria towards glycolysis decreases slowly, but half of the bacteria are still viable after one month. When confined within a mineral environment, bacteria do not form colonies. The exchange of chemical signals between isolated bacteria rather than aggregates can then be studied, a point that could be very important for 'quorum sensing'.

Nassif, Nadine; Bouvet, Odile; Noelle Rager, Marie; Roux, Cécile; Coradin, Thibaud; Livage, Jacques

2002-09-01

232

Sonication-triggered instantaneous gel-to-gel transformation.  

PubMed

Two new peptide-based isomers containing cholesterol and naphthalic groups have been designed and synthesized. We found that the position of L-alanine in the linker could tune the gelation properties and morphologies. The molecule with the L-alanine residue positioned in the middle of the linker (1b) shows better gelation behavior than that with L-alanine directly linked to the naphthalimido moiety (1a). As a result, a highly thermostable organogel of 1b with a unique core-shell structure was obtained at high temperature and pressure in acetonitrile. Moreover, the gels of 1a and 1b could undergo an instantaneous gel-to-gel transition triggered by sonication. Ultrasound could break the core-shell microsphere of 1b and the micelle structure of 1a into entangled fibers. By studying the mechanism of the sonication-triggered gel-to-gel transition process of these compounds, it can be concluded that ultrasound has a variety of effects on the morphology, such as cutting, knitting, unfolding, homogenizing, and even cross-linking. Typically, ultrasound can cleave and homogenize pi-stacking and hydrophobic interactions among the gel molecules and then reshape the morphologies to form a new gel. This mechanism of morphology transformation triggered by sonication might be attractive in the field of material storage and controlled release. PMID:20572172

Yu, Xudong; Liu, Qian; Wu, Junchen; Zhang, Mingming; Cao, Xinhua; Zhang, Song; Wang, Qi; Chen, Liming; Yi, Tao

2010-08-01

233

What is Fitness123? A fitness program designed exclusively for  

E-print Network

: · New to exercise or have lost their motivation to exercise · Intimidated by fitness facilities · Unsure of how to begin an exercise program Join Fitness123 and learn to exercise from supportive instructors of your life with exercise #12;It all starts here. Register and participate in the following classes

Thomas, Andrew

234

Can mobile virtual fitness apps replace human fitness trainer?  

Microsoft Academic Search

The increased need in promoting fitness activity and rapid growth of smart-phones has urged the development of mobile virtual fitness apps (MVFA). Yet, evaluation on these MVFA has been limited and, therefore, this study attempts to conduct preliminary evaluation on randomly sampled MVFA based on our proposed system workflow using theories of social support and persuasive technology, and the American

Ron Kwok Chi-Wai; Stanley Hui Sai-Chuen; Tania Mak So-Ning; Peter Wu Ka-Shun; Ken Lee Wing-Kuen; Clara Wong Choi-Ki

2011-01-01

235

NLINEAR - NONLINEAR CURVE FITTING PROGRAM  

NASA Technical Reports Server (NTRS)

A common method for fitting data is a least-squares fit. In the least-squares method, a user-specified fitting function is utilized in such a way as to minimize the sum of the squares of distances between the data points and the fitting curve. The Nonlinear Curve Fitting Program, NLINEAR, is an interactive curve fitting routine based on a description of the quadratic expansion of the chi-squared statistic. NLINEAR utilizes a nonlinear optimization algorithm that calculates the best statistically weighted values of the parameters of the fitting function and the chi-square that is to be minimized. The inputs to the program are the mathematical form of the fitting function and the initial values of the parameters to be estimated. This approach provides the user with statistical information such as goodness of fit and estimated values of parameters that produce the highest degree of correlation between the experimental data and the mathematical model. In the mathematical formulation of the algorithm, the Taylor expansion of chi-square is first introduced, and justification for retaining only the first term are presented. From the expansion, a set of n simultaneous linear equations are derived, which are solved by matrix algebra. To achieve convergence, the algorithm requires meaningful initial estimates for the parameters of the fitting function. NLINEAR is written in Fortran 77 for execution on a CDC Cyber 750 under NOS 2.3. It has a central memory requirement of 5K 60 bit words. Optionally, graphical output of the fitting function can be plotted. Tektronix PLOT-10 routines are required for graphics. NLINEAR was developed in 1987.

Everhart, J. L.

1994-01-01

236

NMR relaxometry measurements of Fricke gel dosimeters exposed to neutrons  

NASA Astrophysics Data System (ADS)

Fricke infused gel matrices offer several features making them suitable for dosimetric applications; among these there are tissue equivalence, low cost and ease of preparation. Their nuclear magnetic resonance (NMR) relaxation properties can be used as a radiation detector for the dosimetry of beams used in cancer therapy. In recent years neutron capture therapy has been resumed for the treatment of various types of cancer and it requires three-dimensional mapping of the neutron fields. In this work, we investigated this particular application through NMR relaxometry and MR imaging of Fricke gels exposed to neutrons. We analyzed both the R1 and R2 relaxation rates, which relate to the longitudinal T1 and transversal T2 relaxation times. In particular, we found that the relaxation rate R2 does not depend on the neutron fluence, whereas the relaxation rate R1 increases linearly with the fluence. The magnetic resonance imaging acquisitions showed that T1-weighted images allow the characterization of samples exposed to different neutron fluences.

Marrale, Maurizio; Brai, Maria; Longo, Anna; Gallo, Salvatore; Tomarchio, Elio; Tranchina, Luigi; Gagliardo, Cesare; D'Errico, Francesco

2014-11-01

237

Bayesian Reweighting for Global Fits  

E-print Network

Two different techniques for adding additional data sets to existing global fits using Bayesian reweighting have been proposed in the literature. The derivation of each reweighting formalism is critically reviewed. A simple example is constructed that conclusively favors one of the two formalisms. The effects of this choice for global fits is discussed.

Nobuo Sato; J. F. Owens; Harrison Prosper

2013-10-03

238

Do baseline glucocorticoids predict fitness?  

Microsoft Academic Search

Baseline glucocorticoid (cort) levels are increasingly employed as physiological indices of the relative con- dition or health of individuals and populations. Often, high cort levels are assumed to indicate an individual or population in poor condition and with low relative fit- ness (the Cort-Fitness Hypothesis). We review empirical support for this assumption, and find that variation in levels of baseline

Frances Bonier; Paul R. Martin; Ignacio T. Moore; John C. Wingfield

2009-01-01

239

Characterization of rehydrated gelatin gels.  

PubMed

Five percent glutaraldehyde cross-linked gels have shown excellent blood compatibility as coatings for cardiac prostheses. A method was developed for producing thin dehydrated coatings using a proprietary dehydration procedure and ethylene oxide (EO) sterilization. The swollen surfaces of rehydrates versus wet (original) gels were compared. Within 30 min of saline rehydration, dry 30-50-microns films on textured surfaces became smooth, uniform, and comparable to original gelatin gels. Mechanical test results after rehydration showed values for strain remain unchanged (39.3 + 10.0 to 40.0 + 7.8%), but stress increased (2.79 + 1.21 to 4.22 + 1.60 dyne/cm2; p less than 0.01). The contact angle data reported gamma C values of 26.1 and 30.4 dyne/cm for original and rehydrated gels. Using a coulometric titrimeter, the measured water content of original gels was reduced from 85 to 3.4% after drying. Dried and saline rehydrated gels had a 73.2% moisture content. Gels shrank 8.8% of their original length after rehydration; however, the thickness of all pump coatings remained stable. Two-hour incubations with bovine platelet rich plasma showed no differences in platelet reactivity or morphology when compared to original gels. Light microscopy and scanning electron microscopy (SEM) showed no evidence of gel cracking or surface defects after pump endurance testing for 3 and 5 weeks. The process of dehydration eliminates the wet storage and sterility problems of such hydrogels and provides a stable film coating for a variety of blood-contacting substrates. PMID:1998488

Emoto, H; Kambic, H; Chen, J F; Nosé, Y

1991-02-01

240

Magnetic resonance imaging of microbubbles in a superheated emulsion chamber for brachytherapy dosimetry.  

PubMed

This paper describes development of magnetic resonance imaging (MRI) techniques for three-dimensional (3D) imaging of a position-sensitive detector for brachytherapy dosimetry. The detector is a 0.5 l chamber containing an emulsion of halocarbon-115 droplets in a tissue-equivalent glycerin-based gel. The halocarbon droplets are highly superheated and expand into vapor microbubbles upon irradiation. Brachytherapy sources can be inserted into the superheated emulsion chamber to create distributions of bubbles. Three-dimensional MRI of the chamber is then performed. A 3D gradient-echo technique was optimized for spatial resolution and contrast between bubbles and gel. Susceptibility gradients at the interfaces between bubbles and gel are exploited to enhance contrast so microscopic bubbles can be imaged using relatively large voxel sizes. Three-dimensional gradient-echo images are obtained with an isotropic resolution of 300 microns over a 77 mm x 77 mm x 9.6 mm field-of-view in an imaging time of 14 min. A post-processing technique was developed to semi-automatically segment the bubbles from the images and to assess dose distributions based on the measured bubble densities. Relative dose distributions are computed from MR images for a 125I brachytherapy source and the results compare favorably to relative radial dose distributions calculated as recommended by Task Group 43 of the American Association of Physicists in Medicine. PMID:9874823

Lamba, M; Holland, S K; Elson, H; d'Errico, F; Nath, R

1998-12-01

241

FITS Liberator: Image processing software  

NASA Astrophysics Data System (ADS)

The ESA/ESO/NASA FITS Liberator makes it possible to process and edit astronomical science data in the FITS format to produce stunning images of the universe. Formerly a plugin for Adobe Photoshop, the current version of FITS Liberator is a stand-alone application and no longer requires Photoshop. This image processing software makes it possible to create color images using raw observations from a range of telescopes; the FITS Liberator continues to support the FITS and PDS formats, preferred by astronomers and planetary scientists respectively, which enables data to be processed from a wide range of telescopes and planetary probes, including ESO's Very Large Telescope, the NASA/ESA Hubble Space Telescope, NASA's Spitzer Space Telescope, ESA's XMM-Newton Telescope and Cassini-Huygens or Mars Reconnaissance Orbiter.

Lindberg Christensen, Lars; Nielsen, Lars Holm; Nielsen, Kaspar K.; Johansen, Teis; Hurt, Robert; de Martin, David

2012-06-01

242

How do monomeric components of a polymer gel dosimeter respond to ionising radiation: A steady-state radiolysis towards preparation of a 3D polymer gel dosimeter  

NASA Astrophysics Data System (ADS)

Ionising radiation-induced reactions of aqueous single monomer solutions and mixtures of poly(ethylene glycol) diacrylate (PEGDA) and N, N'-methylenebisacrylamide (Bis) in a steady-state condition are presented below and above gelation doses in order to highlight reactions in irradiated 3D polymer gel dosimeters, which are assigned for radiotherapy dosimetry. Both monomers are shown to undergo radical polymerisation and cross-linking, which result in the measured increase in molecular weight and radius of gyration of the formed polydisperse polymer coils. The formation of nanogels was also observed for Bis solutions at a low concentration. In the case of PEGDA-Bis mixtures, co-polymerisation is suggested as well. At a sufficiently high radiation dose, the formation of a polymer network was observed for both monomers and their mixture. For this reason a sol-gel analysis for PEGDA and Bis was performed gravimetrically and a proposition of an alternative to this method employing a nuclear magnetic resonance technique is made. The two monomers were used for preparation of 3D polymer gel dosimeters having the acronyms PABIG and PABIG nx. The latter is presented for the first time in this work and is a type of the formerly established PABIG polymer gel dosimeter. The elementary characteristics of the new composition are presented, underlining the ease of its preparation, low dose threshold, and slightly increased sensitivity but lower quasi-linear range of dose response in comparison to PABIG.

Kozicki, Marek

2011-12-01

243

Adhesive, elastomeric gel impregnating composition  

DOEpatents

An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

Shaw, David Glenn (Tucson, AZ); Pollard, John Randolph (Tucson, AZ); Brooks, Robert Aubrey (Tijeras, NM)

2002-01-01

244

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

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

Rathbone, Bruce A.

2005-02-25

245

Colloidal gels: Clay goes patchy  

NASA Astrophysics Data System (ADS)

Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

Kegel, Willem K.; Lekkerkerker, Henk N. W.

2011-01-01

246

Self polymerising ionic liquid gel.  

PubMed

A novel self-polymerised ionic liquid (IL) gel was prepared at room temperature (RT), without light or heat or addition of initiator, using a new IL, choline formate (CF), and 2-hydroxyethyl methacrylate (HEMA). PMID:19462080

Winther-Jensen, Orawan; Vijayaraghavan, R; Sun, Jiazeng; Winther-Jensen, Bjorn; MacFarlane, Douglas R

2009-06-01

247

A conjugated polymer plastic gel  

E-print Network

We present a gel route to process highly oriented conjugated polymer films and fibers. The incorporation of hexafluoroisopropanol, a strong and stable dipolar group, to the polythiophene backbone enhances the solubility ...

Alcazar Jorba, Daniel

2008-01-01

248

Passive particle dosimetry. [silver halide crystal growth  

NASA Technical Reports Server (NTRS)

Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

Childs, C. B.

1977-01-01

249

Trigeminal neuralgia treatment dosimetry of the Cyberknife.  

PubMed

There are 2 Cyberknife units at Stanford University. The robot of 1 Cyberknife is positioned on the patient's right, whereas the second is on the patient's left. The present study examines whether there is any difference in dosimetry when we are treating patients with trigeminal neuralgia when the target is on the right side or the left side of the patient. In addition, we also study whether Monte Carlo dose calculation has any effect on the dosimetry. We concluded that the clinical and dosimetric outcomes of CyberKnife treatment for trigeminal neuralgia are independent of the robot position. Monte Carlo calculation algorithm may be useful in deriving the dose necessary for trigeminal neuralgia treatments. PMID:21723113

Ho, Anthony; Lo, Anthony T; Dieterich, Sonja; Soltys, Scott G; Gibbs, Iris C; Chang, Steve G; Adler, John R

2012-01-01

250

Trigeminal neuralgia treatment dosimetry of the Cyberknife  

SciTech Connect

There are 2 Cyberknife units at Stanford University. The robot of 1 Cyberknife is positioned on the patient's right, whereas the second is on the patient's left. The present study examines whether there is any difference in dosimetry when we are treating patients with trigeminal neuralgia when the target is on the right side or the left side of the patient. In addition, we also study whether Monte Carlo dose calculation has any effect on the dosimetry. We concluded that the clinical and dosimetric outcomes of CyberKnife treatment for trigeminal neuralgia are independent of the robot position. Monte Carlo calculation algorithm may be useful in deriving the dose necessary for trigeminal neuralgia treatments.

Ho, Anthony [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Lo, Anthony T., E-mail: tonyho22003@yahoo.com [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Dieterich, Sonja; Soltys, Scott G.; Gibbs, Iris C. [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Chang, Steve G.; Adler, John R. [Department of Neurosurgery, Stanford University, Stanford, CA (United States)

2012-04-01

251

Argentine intercomparison programme for personal dosimetry.  

PubMed

An Intercomparison Programme is being carried out in Argentina for individual monitoring services. The programme was designed to test, on a voluntary basis, the performance of the laboratories that provide individual monitoring services for X and gamma radiation fields in the range from low-level dose up to 100 mSv. Irradiations were performed in full accordance with ISO 4037-3 recommendations by the Regional Reference Centre for Dosimetry (CRRD), belonging to Atomic Energy Commission (CNEA) and the Physical Dosimetry Laboratory of the Nuclear Regulatory Authority (ARN). At the same time, several items have been asked to each participant pertaining to the action range, the detectors' characteristics, the laboratory procedures, the existence of an algorithm and its use for the dosemeter evaluation. In this study the evolution of the laboratories' performance throughout the programme, based on ISO 14146 acceptance criteria, is shown. PMID:17848382

Gregori, B N; Papadópulos, S B; Saraví, M; Kunst, J J

2007-01-01

252

Absolute and relative dosimetry for ELIMED  

SciTech Connect

The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

Cirrone, G. A. P.; Schillaci, F.; Scuderi, V. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Institute of Physics Czech Academy of Science, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Institute of Physics Czech Academy of Science, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Carpinelli, M. [INFN Sezione di Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy)] [INFN Sezione di Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Leonora, E.; Randazzo, N. [INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy)] [INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy); Presti, D. Lo [INFN-Sezione di Catania, Via Santa Sofia 64, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy)] [INFN-Sezione di Catania, Via Santa Sofia 64, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Raffaele, L. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy); Tramontana, A. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Cirio, R.; Sacchi, R.; Monaco, V. [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino, Italy and Università di Torino, Dipartimento di Fisica, Via P.Giuria, 1 10125 Torino (Italy)] [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino, Italy and Università di Torino, Dipartimento di Fisica, Via P.Giuria, 1 10125 Torino (Italy); Marchetto, F.; Giordanengo, S. [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino (Italy)] [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino (Italy)

2013-07-26

253

Raft Instability of Biopolymer Gels  

E-print Network

Following recent X-ray diffraction experiments by Wong, Li, and Safinya on biopolymer gels, we apply Onsager excluded volume theory to a nematic mixture of rigid rods and strong ``$\\pi/2$'' cross-linkers obtaining a long-ranged, highly anisotropic depletion attraction between the linkers. This attraction leads to breakdown of the percolation theory for this class of gels, to breakdown of Onsager's second-order virial method, and to formation of heterogeneities in the form of raft-like ribbons.

I. Borukhov; R. F. Bruinsma

2002-09-13

254

Development and optimization of a 2-hydroxyethylacrylate MRI polymer gel dosimeter  

NASA Astrophysics Data System (ADS)

In this study, radiation induced changes in a polymer gel dosimeter manufactured using 2-hydroxyethylacrylate (HEA) and N,N'-methylene-bisacrylamide (BIS) were investigated using magnetic resonance imaging (MRI) and FT-Raman spectroscopy. The variation in magnetic resonance relaxation time (T2) with absorbed dose was modelled assuming fast exchange of magnetization. Overall good agreement between the model and experimental data was obtained. However, comparison with FT-Raman data suggests that not all the protons attached to the polymer contribute to the relaxation process. Furthermore, for certain compositions improved agreement with experimental data was achieved when a lower fraction of polymer protons available for exchange with water was assumed in the low dose region. This indicates that the T2 value is influenced by the composition and topology of the formed polymer, which may vary with absorbed dose. The concept of percentage dose resolution (DpDgr,%) was introduced to enable optimization of gel compositions for use in relative dosimetry applications. This concept was applied to demonstrate the effects of varying the gelatine concentration, the total fraction of monomer/crosslinker (%T) and the relative fraction of crosslinker (%C) on gel performance in HEA gels as well as compare the performance of HEA and a standard polyacrylamide gel (PAG). The percentage dose resolution was improved for all HEA gels compared to the PAG dosimeter containing 3% acrylamide and 3% BIS. Increasing the total concentration of monomer was shown to have the largest single effect. In the range of doses of interest for clinical radiation therapy, DpDgr,% for the optimal HEA gel (4% HEA, 4% BIS) was lower than 2.3%, compared to 3.8% for the PAG dosimeter.

Gustavsson, H.; Bäck, S. Å. J.; Lepage, M.; Rintoul, L.; Baldock, C.

2004-01-01

255

Dosimetry for photodynamic therapy of malignant tumors  

NASA Astrophysics Data System (ADS)

The rationale of photodynamic therapy is based on the cytotoxic action of products generated by excited photosensitizers. Recent development has brought forward a series of promising photosensitizers ranging from hematoporphyrin derivative, various kinds of phthalocyanines and chlorins, to (delta) -aminolevulinic acid. The therapeutic efficacy is dependent on parameters such as tissue oxygenation, sensitizer distribution, drug clearance, optical irradiation, and exposure time. The general outline of a dosimetry model, which enables all these effects to be taken into account, is discussed.

Svaasand, Lars O.

1993-03-01

256

In vivo dosimetry in external beam radiotherapy  

SciTech Connect

In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

Mijnheer, Ben [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam 1066 CX (Netherlands); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Izewska, Joanna [Division of Human Health, International Atomic Energy Agency, Vienna 1400 (Austria); Reft, Chester [Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, Illinois 60637 (United States)

2013-07-15

257

Hanford Internal Dosimetry Project manual. Revision 1  

SciTech Connect

This document describes the Hanford Internal Dosimetry Project, as it is administered by Pacific Northwest Laboratory (PNL) in support of the US Department of Energy and its Hanford contractors. Project services include administrating the bioassay monitoring program, evaluating and documenting assessment of potential intakes and internal dose, ensuring that analytical laboratories conform to requirements, selecting and applying appropriate models and procedures for evaluating radionuclide deposition and the resulting dose, and technically guiding and supporting Hanford contractors in matters regarding internal dosimetry. Specific chapters deal with the following subjects: practices of the project, including interpretation of applicable DOE Orders, regulations, and guidance into criteria for assessment, documentation, and reporting of doses; assessment of internal dose, including summary explanations of when and how assessments are performed; recording and reporting practices for internal dose; selection of workers for bioassay monitoring and establishment of type and frequency of bioassay measurements; capability and scheduling of bioassay monitoring services; recommended dosimetry response to potential internal exposure incidents; quality control and quality assurance provisions of the program.

Carbaugh, E.H.; Bihl, D.E.; MacLellan, J.A.; Long, M.P.

1994-07-01

258

In vivo dosimetry in external beam radiotherapy.  

PubMed

In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20?20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks. PMID:23822404

Mijnheer, Ben; Beddar, Sam; Izewska, Joanna; Reft, Chester

2013-07-01

259

Bayesian Methods for Radiation Detection and Dosimetry  

SciTech Connect

We performed work in three areas: radiation detection, external and internal radiation dosimetry. In radiation detection we developed Bayesian techniques to estimate the net activity of high and low activity radioactive samples. These techniques have the advantage that the remaining uncertainty about the net activity is described by probability densities. Graphs of the densities show the uncertainty in pictorial form. Figure 1 below demonstrates this point. We applied stochastic processes for a method to obtain Bayesian estimates of 222Rn-daughter products from observed counting rates. In external radiation dosimetry we studied and developed Bayesian methods to estimate radiation doses to an individual with radiation induced chromosome aberrations. We analyzed chromosome aberrations after exposure to gammas and neutrons and developed a method for dose-estimation after criticality accidents. The research in internal radiation dosimetry focused on parameter estimation for compartmental models from observed compartmental activities. From the estimated probability densities of the model parameters we were able to derive the densities for compartmental activities for a two compartment catenary model at different times. We also calculated the average activities and their standard deviation for a simple two compartment model.

Peter G. Groer

2002-09-29

260

Surface grafted chitosan gels. Part II. Gel formation and characterization.  

PubMed

Responsive biomaterial hydrogels attract significant attention due to their biocompatibility and degradability. In order to make chitosan based gels, we first graft one layer of chitosan to silica, and then build a chitosan/poly(acrylic acid) multilayer using the layer-by-layer approach. After cross-linking the chitosan present in the polyelectrolyte multilayer, poly(acrylic acid) is partly removed by exposing the multilayer structure to a concentrated carbonate buffer solution at a high pH, leaving a surface-grafted cross-linked gel. Chemical cross-linking enhances the gel stability against detachment and decomposition. The chemical reaction between gluteraldehyde, the cross-linking agent, and chitosan was followed in situ using total internal reflection Raman (TIRR) spectroscopy, which provided a molecular insight into the complex reaction mechanism, as well as the means to quantify the cross-linking density. The amount of poly(acrylic acid) trapped inside the surface grafted films was found to decrease with decreasing cross-linking density, as confirmed in situ using TIRR, and ex situ by Fourier transform infrared (FTIR) measurements on dried films. The responsiveness of the chitosan-based gels with respect to pH changes was probed by quartz crystal microbalance with dissipation (QCM-D) and TIRR. Highly cross-linked gels show a small and fully reversible behavior when the solution pH is switched between pH 2.7 and 5.7. In contrast, low cross-linked gels are more responsive to pH changes, but the response is fully reversible only after the first exposure to the acidic solution, once an internal restructuring of the gel has taken place. Two distinct pKa's for both chitosan and poly(acrylic acid), were determined for the cross-linked structure using TIRR. They are associated with populations of chargeable groups displaying either a bulk like dissociation behavior or forming ionic complexes inside the hydrogel film. PMID:25006685

Liu, Chao; Thormann, Esben; Claesson, Per M; Tyrode, Eric

2014-07-29

261

Pre-Cast Gel Electrophoresis Guide  

E-print Network

Novex® Pre-Cast Gel Electrophoresis Guide Version B January 27, 2003 IM-1002 Novex® Pre-Cast Gel Electrophoresis Guide General information and protocols for using Novex® pre-cast gels www.invitrogen.com tech.....................................................................................................................1 Novex® Pre-Cast Gels

Kirschner, Marc W.

262

"Fitness Freaks": A Healthier Lifestyle?  

ERIC Educational Resources Information Center

This article examines the extent to which the lifestyles of young people are affected by health and fitness considerations. An analysis of data from 3253 Health Related Behavior Questionnaires, completed by fourth-year secondary school pupils is presented. (IAH)

Balding, John

1989-01-01

263

Flexible fitting for fluid lines  

NASA Technical Reports Server (NTRS)

Tube fitting, consisting of movable tubular section containing two spring pressure Teflon actuated low friction seals, two standard connectors, and two hexagonal retaining nuts, provides flexible joint that allows axial and rotational motion.

Barajas, S. L.

1976-01-01

264

Kinematic Fitting of Detached Vertices  

SciTech Connect

The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

Paul Mattione

2007-05-01

265

fpack: FITS Image Compression Program  

NASA Astrophysics Data System (ADS)

fpack is a utility program for optimally compressing images in the FITS data format. The associated funpack program will restore the compressed file back to its original state. These programs may be run from the host operating system command line and are analogous to the gzip and gunzip utility programs, except that they are specifically optimized for FITS format images and offer a wider choice of compression options. fpack uses the tiled image compression convention for storing the compressed images. This convention can in principle support any number of of different compression algorithms; currently GZIP, Rice, Hcompress, and the IRAF pixel list compression algorithms have been implemented. The main advantages of fpack compared to the commonly used technique of externally compressing the whole FITS file with gzip are: It is generally faster and offers better compression than gzip.The FITS header keywords remain uncompressed for fast access.Each HDU of a multi-extension FITS file is compressed separately, so it is not necessary to uncompress the entire file to read a single image in a multi-extension file.Dividing the image into tiles before compression enables faster access to small subsections of the image.The compressed image is itself a valid FITS file and can be manipulated by other general FITS utility software.Lossy compression can be used for much higher compression in cases where it is not necessary to exactly preserve the original image.The CHECKSUM keywords are automatically updated to help verify the integrity of the files.Software that supports the tiled image compression technique can directly read and write the FITS images in their compressed form.

Seaman, Rob; Pence, William; White, Rick

2010-10-01

266

Athletic Shoe Fit and Modifications  

Microsoft Academic Search

\\u000a Whether treating professional athletes or weekend warriors, it is critical to select the right shoes and get the correct fit.\\u000a Some foot-care professionals fit patients themselves, while others refer patients out to stores that decide what is best.\\u000a Either way, patients’ needs are best served by the sports medicine specialist assessing the functional biomechanics of the\\u000a lower extremity, identifying structural

Josh White

267

A position-sensitive superheated emulsion chamber for three-dimensional photon dosimetry  

NASA Astrophysics Data System (ADS)

A position-sensitive detector chamber is introduced for the three-dimensional (3D) dosimetry of photon-emitting brachytherapy sources. The detector is based on an extremely fine suspension of monochloropentafluoroethane droplets emulsified in a gel. The droplets are highly superheated at room temperature and their evaporation can be triggered by photon interactions, leading to the formation of microscopic bubbles. Thus, when photon-emitting brachytherapy sources are inserted into the detector, bubble distributions form around them, enabling visualization of the radiation field. The tissue-equivalent emulsifier gel is highly viscous and keeps the bubbles immobilized at the location of their formation. Bubbles can then be imaged by nuclear magnetic resonance or optical scanning techniques. After the imaging, the detector can be pressurized in order to recondense the bubbles to the liquid phase. In a few minutes, the device is annealed and ready to be used again for repeated measurements improving the counting statistics. The photon sensitivity of the monochloropentafluoroethane droplets was determined with highly filtered, quasi-monochromatic x-ray beams and radionuclide sources. The air-kerma response presents a broad maximum at low energies, due to the relatively high effective atomic number of the halocarbon molecule. A prototype chamber was built and successfully tested: bubble distributions deriving from the insertion of a source were imaged by means of a slice-selective 3D gradient-echo technique. These experiments confirm the potential and viability of this new approach to 3D photon dosimetry.

d'Errico, Francesco; Nath, Ravinder; Lamba, Michael; Holland, Scott K.

1998-05-01

268

Effect of recent changes in atomic bomb survivor dosimetry on cancer mortality risk estimates.  

PubMed

The Radiation Effects Research Foundation has recently implemented a new dosimetry system, DS02, to replace the previous system, DS86. This paper assesses the effect of the change on risk estimates for radiation-related solid cancer and leukemia mortality. The changes in dose estimates were smaller than many had anticipated, with the primary systematic change being an increase of about 10% in gamma-ray estimates for both cities. In particular, an anticipated large increase of the neutron component in Hiroshima for low-dose survivors did not materialize. However, DS02 improves on DS86 in many details, including the specifics of the radiation released by the bombs and the effects of shielding by structures and terrain. The data used here extend the last reported follow-up for solid cancers by 3 years, with a total of 10,085 deaths, and extends the follow-up for leukemia by 10 years, with a total of 296 deaths. For both solid cancer and leukemia, estimated age-time patterns and sex difference are virtually unchanged by the dosimetry revision. The estimates of solid-cancer radiation risk per sievert and the curvilinear dose response for leukemia are both decreased by about 8% by the dosimetry revision, due to the increase in the gamma-ray dose estimates. The apparent shape of the dose response is virtually unchanged by the dosimetry revision, but for solid cancers, the additional 3 years of follow-up has some effect. In particular, there is for the first time a statistically significant upward curvature for solid cancer on the restricted dose range 0-2 Sv. However, the low-dose slope of a linear-quadratic fit to that dose range should probably not be relied on for risk estimation, since that is substantially smaller than the linear slopes on ranges 0-1 Sv, 0-0.5 Sv, and 0- 0.25 Sv. Although it was anticipated that the new dosimetry system might reduce some apparent dose overestimates for Nagasaki factory workers, this did not materialize, and factory workers have significantly lower risk estimates. Whether or not one makes allowance for this, there is no statistically significant city difference in the estimated cancer risk. PMID:15447045

Preston, Dale L; Pierce, Donald A; Shimizu, Yukiko; Cullings, Harry M; Fujita, Shoichiro; Funamoto, Sachiyo; Kodama, Kazunori

2004-10-01

269

The use of normoxic polymer gel for measuring dose distributions of 1, 4 and 30 mm cones  

NASA Astrophysics Data System (ADS)

This study demonstrates the use of normoxic polymer gel for measuring dose distributions of small fields that lack lateral electronic equilibrium. Two different types of normoxic polymer gel, MAGAT and PAGAT, are studied in a larger field (10 cm×10 cm) and 1, 4 and 30 mm cones to obtain cone factors, dose profiles and percentage depth doses. These results were then compared to KODAK XV film measurements and BEAMnrc Monte Carlo simulations. The results show that the sensitivity of PAGAT gel is 0.090±0.074 s-1 Gy-1, which may not be suitable for small-field dosimetry with a 0.3 mm resolution scanned using a 3 T MR imager in a dose range lower than 2.5 Gy. There are good agreements between cone factors estimated using KODAK XV film and MAGAT gel. In a dose profile comparison, good dose agreement among MAGAT gel, XV film and MC simulation can be seen in the central area for a 30 mm cone. In penumbra, the distance to agreement is at most 1.2 mm (4 pixel), and less than 0.3 mm (1 pixel) for 4 and 1 mm cones. In a percentage depth dose comparison, there were good agreements between MAGAT and MC up to a depth of 8 cm. Possible factors for gel uncertainty such as MRI magnetic field inhomogeneity and temperature were also investigated.

Lee, C. C.; Wu, J. F.; Chang, K. P.; Chu, C. H.; Wey, S. P.; Liu, H. L.; Tung, C. J.; Wu, S. W.; Chao, T. C.

2014-11-01

270

Human Biodistribution and Dosimetry of 11 C-CUMI-101,  

E-print Network

Human Biodistribution and Dosimetry of 11 C-CUMI-101, an Agonist Radioligand for Serotonin-1A and Dosimetry of 11 C-CUMI-101, an Agonist Radioligand for Serotonin-1A Receptors in Brain. PLoS ONE 6(9): e

Shen, Jun

271

In vivo dosimetry during external photon beam radiotherapy  

Microsoft Academic Search

In this critical review of the current practice of patient dose verification, we first demonstrate that a high accuracy (about 1–2%, 1 SD) can be obtained. Accurate in vivo dosimetry is possible if diodes and thermoluminescence dosimeters (TLDs), the main detector types in use for in vivo dosimetry, are carefully calibrated and the factors influencing their sensitivity are taken into

Marion Essers; BenJ Mijnheer

1999-01-01

272

MCNP modeling of prostate brachytherapy and organ dosimetry  

E-print Network

MCNP MODELING OF PROSTATE BRACHYTHERAPY AND ORGAN DOSIMETRY A Thesis by SUSRUT RAJANIKANT USGAONKER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE May 2003 Major Subject: Health Physics MCNP MODELING OF PROSTATE BRACHYTHERAPY AND ORGAN DOSIMETRY A Thesis by SUSRUT RAJANIKANT USGAONKER Submitted to Texas A...

Usgaonker, Susrut Rajanikant

2004-09-30

273

Comparison of uncertainty metrics for calculated dosimetry activities  

SciTech Connect

Various metrics are formulated for the uncertainty of calculated neutron activities for dosimetry reactions. The correlations between the uncertainty metrics are examined. The uncertainty data are presented for the dosimetry reactions and can be used to guide the selection of sensors used in spectrum determinations.

Griffin, P.J.

1996-02-01

274

Measured, modeled, and causal conceptions of fitness  

PubMed Central

This paper proposes partial answers to the following questions: in what senses can fitness differences plausibly be considered causes of evolution?What relationships are there between fitness concepts used in empirical research, modeling, and abstract theoretical proposals? How does the relevance of different fitness concepts depend on research questions and methodological constraints? The paper develops a novel taxonomy of fitness concepts, beginning with type fitness (a property of a genotype or phenotype), token fitness (a property of a particular individual), and purely mathematical fitness. Type fitness includes statistical type fitness, which can be measured from population data, and parametric type fitness, which is an underlying property estimated by statistical type fitnesses. Token fitness includes measurable token fitness, which can be measured on an individual, and tendential token fitness, which is assumed to be an underlying property of the individual in its environmental circumstances. Some of the paper's conclusions can be outlined as follows: claims that fitness differences do not cause evolution are reasonable when fitness is treated as statistical type fitness, measurable token fitness, or purely mathematical fitness. Some of the ways in which statistical methods are used in population genetics suggest that what natural selection involves are differences in parametric type fitnesses. Further, it's reasonable to think that differences in parametric type fitness can cause evolution. Tendential token fitnesses, however, are not themselves sufficient for natural selection. Though parametric type fitnesses are typically not directly measurable, they can be modeled with purely mathematical fitnesses and estimated by statistical type fitnesses, which in turn are defined in terms of measurable token fitnesses. The paper clarifies the ways in which fitnesses depend on pragmatic choices made by researchers. PMID:23112804

Abrams, Marshall

2012-01-01

275

Capillary fracture of soft gels  

E-print Network

A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact-line in a starburst pattern. In this paper, we characterize i) the initiation process in which the number of arms in the starburst is controlled by the ratio of surface tension contrast to the gel's elastic modulus and ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law $L\\propto t^{3/4}$. We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid/solid wetting forces. The elastic solution shows that both the location and magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an impo...

Bostwick, Joshua B

2013-01-01

276

Capillary fracture of soft gels  

E-print Network

A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact-line in a starburst pattern. In this paper, we characterize i) the initiation process in which the number of arms in the starburst is controlled by the ratio of surface tension contrast to the gel's elastic modulus and ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law $L\\propto t^{3/4}$. We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid/solid wetting forces. The elastic solution shows that both the location and magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an important factor in the fracture process, as it can help mitigate large surface tractions; this finding is confirmed with experiments. We then develop a model for crack propagation by considering the transport of an inviscid fluid into the fracture tip of an incompressible material, and find that a simple energy-conservation argument can explain the observed material-independent power law. We compare predictions for both linear elastic and neo-Hookean solids finding that the latter better explains the observed exponent.

Joshua B. Bostwick; Karen E. Daniels

2013-10-16

277

Evaluation of respirator fit training by quantitative fit testing  

E-print Network

was to evaluate the effect-iveness of a respirator use training program in terms of actual fac piece fit before and after training. Two groups of volunteer test subjects were quartitatively fit tested with half-mask respirators at three po1nts in time. One... group received training in respirator use and fittina techniques. The other group did not rece1ve any training. None of the test subjects had any prior experience with half-mask respirators before their participation in this project. The raw data...

Chute, Daniel Otis

2012-06-07

278

Normoxic polyacrylamide gel doped with iodine: response versus X-ray energy.  

PubMed

The basis of Synchrotron Stereotactic Radio-Therapy (SSRT) is the incorporation of high atomic number atoms (iodine, for example) into the tumour mass followed by an irradiation with a monochromatic, low energy, X-ray beam from a synchrotron source. The purpose of the present study was to determine whether polymer gel dosimetry could be used to measure the enhancement of absorbed energy induced by the iodine in the media. We have used a standard nPAG formulation, loaded with NaI and the irradiations were performed either with monochromatic X-rays at the ESRF medical beamline or with a conventional 6 MV X-ray beam from a linear accelerator at the Grenoble University Hospital. We observed sensitivity increase with iodine loaded gels irradiated at low energies, in good agreement with the theoretical iodine dose-enhancement. As expected, the response of the iodine-doped polymer gel was not increased after irradiation with mega-voltage X-rays. We demonstrate in this study that polymer gel dosimeters can be used for measuring dose-enhancement due to iodine presence in SSR treatment. PMID:18602237

Gastaldo, Jérôme; Boudou, Caroline; Lamalle, Laurent; Troprès, Irène; Corde, Stéphanie; Sollier, Albéric; Rucka, Günther; Elleaume, Hélène

2008-12-01

279

Dosimetric characterization of CyberKnife radiosurgical photon beams using polymer gels  

SciTech Connect

Dose distributions registered in water equivalent, polymer gel dosimeters were used to measure the output factors and off-axis profiles of the radiosurgical photon beams employed for CyberKnife radiosurgery. Corresponding measurements were also performed using a shielded silicon diode commonly employed for CyberKnife commissioning, the PinPoint ion chamber, and Gafchromic EBT films, for reasons of comparison. Polymer gel results of this work for the output factors of the 5, 7.5, and 10 mm diameter beams are (0.702{+-}0.029), (0.872{+-}0.039), and (0.929{+-}0.041), respectively. Comparison of polymer gel and diode measurements shows that the latter overestimate output factors of the two small beams (5% for the 5 mm beam and 3% for the 7.5 mm beams). This is attributed to the nonwater equivalence of the high atomic number silicon material of the diode detector. On the other hand, the PinPoint chamber is found to underestimate output factors up to 10% for the 5 mm beam due to volume averaging effects. Polymer gel and EBT film output factor results are found in close agreement for all beam sizes, emphasizing the importance of water equivalence and fine detector sensitive volume for small field dosimetry. Relative off-axis profile results are in good agreement for all dosimeters used in this work, with noticeable differences observed only in the PinPoint estimate of the 80%-20% penumbra width, which is relatively overestimated.

Pantelis, E.; Antypas, C.; Petrokokkinos, L.; Karaiskos, P.; Papagiannis, P.; Kozicki, M.; Georgiou, E.; Sakelliou, L.; Seimenis, I. [Medical Physics Department, Iatropolis - Magnitiki Tomografia Clinic and Diagnostic Center, Ethnikis Antistaseos 54-56, Chalandri, 152 31, Athens (Greece); Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece) and Institute of Accelerating Systems and Applications (IASA), PO Box 17214, GR-10024 Athens (Greece); Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Faculty of Textile Engineering and Marketing, Department of Textile Finishing, Technical University of Lodz, Zeromskiego 116, 90-543 Lodz (Poland); Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece) and Institute of Accelerating Systems and Applications (IASA), PO Box 17214, GR-10024 Athens (Greece); Medical Diagnostic Center Ayios Therissos, 92 Troodous Avenue, Strovolos, Nicosia (Cyprus)

2008-06-15

280

Physical fitness, aging, and sexuality.  

PubMed

Sexuality is a major quality-of-life issue, even into advanced age. Although relatively few studies have addressed sexuality, most studies have emphasized the decline in both sexual performance and satisfaction with aging. In an effort to assess possible positive modifiers of the decline, we included questions concerning sexuality in a multipurpose 90-item questionnaire submitted to members of the Fifty Plus Fitness Association based in Stanford, California. This group is unique in its commitment to a very active lifestyle and has served as a cohort for many prior studies related to fitness and medical outcomes. Sixty-seven percent of the membership returned the mail questionnaire, and 59% of these respondents replied to the sexually relevant items. The results indicated a high level of sexual activity and satisfaction in both older men and women of the Fifty Plus Fitness Association members. Further, sexual satisfaction seemed to correlate with the degree of fitness. We conclude that physical fitness and high levels of sexual activity are mutually supportive elements of successful aging. PMID:10214104

Bortz, W M; Wallace, D H

1999-03-01

281

Fitting Cosmological Data Compilation Model  

NSDL National Science Digital Library

The 1998 discovery of the cosmic acceleration with supernovae was recently awarded the 2011 Nobel Prize in Physics. More observations continue to support this accelerated expansion of the universe (cosmic acceleration). The EJS âFitting Cosmological Data Compilationâ model includes several cosmological surveys for five different observations of the expansion, all of which support a cosmic acceleration. The simulation allows users to compare and fit theoretical models of cosmology with recent supernovae, gamma-ray bursts, the Hubble Parameter, baryon acoustic oscillations, and the CMB data sets to confirm the accelerated expansion of the universe. This modeling allows the user to vary cosmological parameters within a particular class of dark energy cosmological models to fit a particular cosmological data set. The user can plot several theoretical curves with the data to compare different models. The values of these parameters, for a particular model, determine the physical description and evolution of the universe. The EJS âFitting Cosmological Data Compilationâ model was created using Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_Fitting_Cosmological_Data_Compilation.jar file will run the program if Java is installed. You can modify this simulation if you have EJS by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item.

Moldenhauer, Jacob; Stone, Keenan; Shuler, Zeke; Engelhardt, Larry

2012-08-27

282

Fitting Cosmological Supernovae Data Model  

NSDL National Science Digital Library

The Fitting Cosmological Supernovae Data Model allows users to compare and fit cosmological models with recent supernovae type Ia datasets to confirm the accelerated expansion of the universe. The 2011 Nobel Prize in Physics was awarded for the discovery of the cosmic acceleration using Supernovae Type Ia. This simulation allows the user to vary cosmological parameters within a particular class of dark energy cosmological models to fit a particular supernovae dataset. The simulation can plot several theoretical curves with the supernovae data to compare different models. The values of these parameters, for a particular model, determine the physical description and evolution of the universe. The Fitting Cosmological Supernovae Data Model model was created using Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_Fitting_Cosmological_Models_Supernovae.jar file will run the program if Java is installed. You can modify this simulation if you have EJS by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item.

Moldenhauer, Jacob; Engelhardt, Larry; Stone, Keenan

2011-12-08

283

Digital Fitness Connector: Smart Wearable System  

Microsoft Academic Search

Sports and fitness are increasingly getting attention of companies and researchers around the world. In particular, recent mobile devices with hardware GPS and accelerometers, has made possible variety of sports and fitness applications that were not possible earlier. This paper investigates trends in fitness devices, proposes new fitness device system architecture. Proposed Digital Fitness Connector (DFC) architecture leverages existing technologies

Nisheeth Gupta; Sruti Jilla

2011-01-01

284

North Carolina Children and Youth Fitness Study.  

ERIC Educational Resources Information Center

Discusses results from the North Carolina Children and Youth Fitness Study as they relate to national fitness norms, addresses questions concerning youth fitness levels at state and national levels, encourages states to organize similar statewide studies, and compares results from North Carolina's fitness testing with Healthy People 2000 fitness

Davis, Kathryn L.; And Others

1994-01-01

285

Implementation of Health Fitness Exercise Programs.  

ERIC Educational Resources Information Center

This monograph includes the following articles to aid in implementation of fitness concepts: (1) "Trends in Physical Fitness: A Personal Perspective" (H. Harrison Clarke); (2) "A Total Health-Fitness Life-Style" (Steven N. Blair); (3) "Objectives for the Nation--Physical Fitness and Exercise" (Jack H. Wilmore); (4) "A New Physical Fitness Test"…

Cundiff, David E., Ed.

286

Dosimetry for Small Animal Studies Radiation Medicine Program, Princess Margaret Hospital  

E-print Network

Dosimetry for Small Animal Studies Radiation Medicine Program, Princess Margaret Hospital · Image-guidance Kilovoltage Radiation Sources (100-320 kVp) #12;Absolute Dosimetry · Absolute dosimetry #12;Relative Dosimetry · Percent depth dose (PDD) and relative output factors (ROF) · Small volume (0

287

Combination of DG-FDTD with a Substitution Model for Calculating Local Dosimetry in a  

E-print Network

Combination of DG-FDTD with a Substitution Model for Calculating Local Dosimetry in a Variable, multiscale, numerical dosimetry. I. INTRODUCTION Numerical dosimetry is an essential approach to these multiscale aspects, dosimetry problems have naturally a variable feature as the position of the person or its

Paris-Sud XI, Université de

288

Copolymers For Capillary Gel Electrophoresis  

DOEpatents

This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

Liu, Changsheng (State College, PA); Li, Qingbo (State College, PA)

2005-08-09

289

Performance of the CEDS Accident Dosimetry System at the 1995 Los Alamos National Laboratory Nuclear Accident Dosimetry Intercomparison  

Microsoft Academic Search

In July 1995, LANL hosted an accident dosimetry intercomparison. When all reactors on the Oak Ridge Reservation were idled in 1988, the Health Physics Research Reactor (HPRR), which had been used for 22 previous intercomparisons dating from 1965, was shut down for an indefinite period. The LANL group began characterization of two critical assemblies for dosimetry purposes. As a result,

K. L. McMahan; L. J. Schwanke

1996-01-01

290

An alternative to mode fitting  

NASA Astrophysics Data System (ADS)

The space mission CoRoT provides us with a large amount of high-duty cycle long-duration observations. Mode fitting has proven to be efficient for the complete and detailed analysis of the oscillation pattern, but remains time consuming. Furthermore, the photometric background due to granulation severely complicates the analysis. Therefore, we attempt to provide an alternative to mode fitting, for the determination of large separations. With the envelope autocorrelation function and a dedicated filter, it is possible to measure the variation of the large separation independently for the ridges with even and odd degrees. The method appears to be as accurate as the mode fitting. It can be very easily implemented and is very rapid.

Mosser, B.

2010-12-01

291

The Soldier Fitness Tracker: Global Delivery of Comprehensive Soldier Fitness  

ERIC Educational Resources Information Center

Carefully implemented technology strategies are vital to the success of large-scale initiatives such as the U.S. Army's Comprehensive Soldier Fitness (CSF) program. Achieving the U.S. Army's vision for CSF required a robust information technology platform that was scaled to millions of users and that leveraged the Internet to enable global reach.…

Fravell, Mike; Nasser, Katherine; Cornum, Rhonda

2011-01-01

292

Statistical physics of polymer gels  

NASA Astrophysics Data System (ADS)

This work presents a comprehensive analysis of the statistical mechanics of randomly cross-linked polymer gels, starting from a microscopic model of a network made of instantaneously cross-linked Gaussian chains with excluded volume, and ending with the derivation of explicit expressions for the thermodynamic functions and for the density correlation functions which can be tested by experiments. Using replica field theory we calculate the mean field density in replica space and show that this solution contains statistical information about the behavior of individual chains in the network. The average monomer positions change affinely with macroscopic deformation and fluctuations about these positions are limited to length scales of the order of the mesh size. We prove that a given gel has a unique state of microscopic equilibrium which depends on the temperature, the solvent, the average monomer density and the imposed deformation. This state is characterized by the set of the average positions of all the monomers or, equivalently, by a unique inhomogeneous monomer density profile. Gels are thus the only known example of equilibrium solids with no long-range order. We calculate the RPA density correlation functions that describe the statistical properties of small deviations from the average density, due to both static spatial heterogeneities (which characterize the inhomogeneous equilibrium state) and thermal fluctuations (about this equilibrium). We explain how the deformation-induced anisotropy of the inhomogeneous equilibrium density profile is revealed by small angle neutron scattering and light scattering experiments, through the observation of the butterfly effect. We show that all the statistical information about the structure of polymer networks is contained in two parameters whose values are determined by the conditions of synthesis: the density of cross-links and the heterogeneity parameter. We find that the structure of instantaneously cross-linked gels becomes increasingly inhomogeneous with the approach to the cross-link saturation threshold at which the heterogeneity parameter diverges. Analytical expressions for the correlators of deformed gels are derived in both the long wavelength and the short wavelength limits and an exact expression for the total static structure factor, valid for arbitrary wavelengths, is obtained for gels in the state of preparation. We adapt the RPA results to gels permeated by free labelled chains and to gels in good solvents (in the latter case, excluded volume effects are taken into account exactly) and make predictions which can be directly tested by scattering and thermodynamic experiments. Finally, we discuss the limitations and the possible extensions of our work.

Panyukov, Sergei; Rabin, Yitzhak

1996-05-01

293

Tracer diffusion in colloidal gels  

E-print Network

Computer simulations were done of the mean square displacement (MSD) of tracer particles in colloidal gels formed by diffusion or reaction limited aggregation of hard spheres. The diffusion coefficient was found to be determined by the volume fraction accessible to the spherical tracers ($\\phi_a$) independent of the gel structure or the tracer size. In all cases, critical slowing down was observed at $\\phi_a\\approx 0.03$ and was characterized by the same scaling laws reported earlier for tracer diffusion in a Lorentz gas. Strong heterogeneity of the MSD was observed at small $\\phi_a$ and was related to the size distribution of pores.

Sujin Babu; Jean Christophe Gimel; Taco Nicolai

2007-05-09

294

Collagen fiber alignment does not explain mechanical anisotropy in fibroblast populated collagen gels.  

PubMed

Many load-bearing soft tissues exhibit mechanical anisotropy. In order to understand the behavior of natural tissues and to create tissue engineered replacements, quantitative relationships must be developed between the tissue structures and their mechanical behavior. We used a novel collagen gel system to test the hypothesis that collagen fiber alignment is the primary mechanism for the mechanical anisotropy we have reported in structurally anisotropic gels. Loading constraints applied during culture were used to control the structural organization of the collagen fibers of fibroblast populated collagen gels. Gels constrained uniaxially during culture developed fiber alignment and a high degree of mechanical anisotropy, while gels constrained biaxially remained isotropic with randomly distributed collagen fibers. We hypothesized that the mechanical anisotropy that developed in these gels was due primarily to collagen fiber orientation. We tested this hypothesis using two mathematical models that incorporated measured collagen fiber orientations: a structural continuum model that assumes affine fiber kinematics and a network model that allows for nonaffine fiber kinematics. Collagen fiber mechanical properties were determined by fitting biaxial mechanical test data from isotropic collagen gels. The fiber properties of each isotropic gel were then used to predict the biaxial mechanical behavior of paired anisotropic gels. Both models accurately described the isotropic collagen gel behavior. However, the structural continuum model dramatically underestimated the level of mechanical anisotropy in aligned collagen gels despite incorporation of measured fiber orientations; when estimated remodeling-induced changes in collagen fiber length were included, the continuum model slightly overestimated mechanical anisotropy. The network model provided the closest match to experimental data from aligned collagen gels, but still did not fully explain the observed mechanics. Two different modeling approaches showed that the level of collagen fiber alignment in our uniaxially constrained gels cannot explain the high degree of mechanical anisotropy observed in these gels. Our modeling results suggest that remodeling-induced redistribution of collagen fiber lengths, nonaffine fiber kinematics, or some combination of these effects must also be considered in order to explain the dramatic mechanical anisotropy observed in this collagen gel model system. PMID:17887889

Thomopoulos, Stavros; Fomovsky, Gregory M; Chandran, Preethi L; Holmes, Jeffrey W

2007-10-01

295

Self-Sealing Cryogenic Fitting  

NASA Technical Reports Server (NTRS)

Self-sealing fitting for cryogenic tubes remains free of leakage from room temperature to liquid-helium temperature even at internal pressure as high as 2.7 MPa. Fitting comprises parts made of materials with different coefficients of thermal expansion to prevent leakage gaps from forming as temperature decreases. Consists of coupling nut, two flared tube ends, and flared O-ring spacer. Spacer contracts more than tube ends do as temperature decreases. This greater contraction seals tube ends more tightly, preventing leakage.

Jia, Lin Xiang; Chow, Wen Lung; Moslemian, Davood; Lin, Gary; Melton, Greg

1994-01-01

296

Neutron dosimetry for low dose rate Cf-252 AT sources and adherence to recent clinical dosimetry protocol for brachytherapy  

SciTech Connect

In 1995, the American Association of Physicists in Medicine Task Group 43 (AAPM TG-43) published a protocol obsoleting all mixed-field radiation dosimetry for Cf-252. Recommendations for a new brachytherapy dosimetry formalism made by this Task Group favor quantification of source strength in terms of air kerma rather than apparent Curies or other radiation units. Additionally, representation of this dosimetry data in terms of radial dose functions, anisotropy functions, geometric factors, and dose rate constants are in an angular and radial (spherical) coordinate system as recommended, rather than the along-away dosimetry data (Cartesian coordinate system) currently available. This paper presents the initial results of calculated neutron dosimetry in a water phantom for a Cf-252 applicator tube (AT) type medical source soon available from Oak Ridge National Laboratory (ORNL).

Rivard, M.J.; Wierzbicki, J.G.; Van den Heuvel, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Radiation Oncology; Martin, R.C. [Oak Ridge National Lab., TN (United States). Chemical Technology Div.

1997-12-01

297

Improving neutron dosimetry using bubble detector technology  

SciTech Connect

Providing accurate neutron dosimetry for a variety of neutron energy spectra is a formidable task for any dosimetry system. Unless something is known about the neutron spectrum prior to processing the dosimeter, the calculated dose may vary greatly from that actually encountered; that is until now. The entrance of bubble detector technology into the field of neutron dosimetry has eliminated the necessity of having an a priori knowledge of the neutron energy spectra. Recently, a new approach in measuring personnel neutron dose equivalent was developed at Oak Ridge National Laboratory. By using bubble detectors in combination with current thermoluminescent dosimeters (TLDs) as a Combination Personnel Neutron Dosimeter (CPND), not only is it possible to provide accurate dose equivalent results, but a simple four-interval neutron energy spectrum is obtained as well. The components of the CPND are a Harshaw albedo TLD and two bubble detectors with theoretical energy thresholds of 100 key and 1500 keV. Presented are (1) a synoptic history surrounding emergence of bubble detector technology, (2) a brief overview of the current theory on mechanisms of interaction, (3) the data and analysis process involved in refining the response functions, (4) performance evaluation of the original CPND and a reevaluation of the same data under the modified method, (5) the procedure used to determine the reference values of component fluence and dose equivalent for field assessment, (6) analysis of the after-modification results, (7) a critique of some currently held assumptions, offering some alternative explanations, and (8) thoughts concerning potential applications and directions for future research.

Buckner, M.A.

1993-02-01

298

USF/Russian dosimetry on STS-57  

NASA Technical Reports Server (NTRS)

The major purpose of this experiment was to conduct an international comparison of passive dosimetry methods in space. Two APD's were flown in the charged particle directional spectrometer (CPDS)/tissue equivalent proportional counter (TEPC) locker on the space shuttle during the STS-57 mission. Due to placement, the shielding and radiation environment of the APD's were nearly the same and the dosimeters distributed in the two boxes can be considered equally exposed. The dosimeter types included plastic nuclear track detectors (PNTD's), thermoluminescent detectors (TLD), nuclear emulsions, and thermal/resonance neutron detectors (TRND's). The USF dosimeters included PNTD's, TLD's, and TRND's, while the Russian dosimeters included PNTD's, TLD's, and nuclear emulsions.

1995-01-01

299

Dosimetry challenges for implementing emerging technologies  

PubMed Central

During the last 10 years, radiation therapy technologies have gone through major changes, mainly related introduction of sophisticated delivery and imaging techniques to improve the target localization accuracy and dose conformity. While implementation of these emerging technologies such as image-guided SRS/SBRT, IMRT/IMAT, IGRT, 4D motion management, and special delivery technologies showed substantial clinical gains for patient care, many other factors, such as training/quality, efficiency/efficacy, and cost/effectiveness etc. remain to be challenging. This talk will address technical challenges for dosimetry verification of implementing these emerging technologies in radiation therapy. PMID:21617745

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

2010-01-01

300

The next decade in external dosimetry  

SciTech Connect

As the radiation protection community moves through the last half of the '80s and into the next decade, we can expect the requirements for external dosimetry to become increasingly more restrictive and demanding. As in other health protection fields, growing regulatory and legal pressures, together with a natural evolution in philosophy, require the health physicist to display an increasing degree of accountability, rigor, and professionalism. The good news is that, for the most part, the technology necessary to solve many of the problems will be available or not far behind. This paper describes anticipated technology. 66 refs., 10 figs.

Griffith, R.V.

1986-10-01

301

Characterization of new materials for fiberoptic dosimetry  

NASA Astrophysics Data System (ADS)

In this work we have investigated the radioluminescence (RL) characteristics of three materials (Mg2SiO4:Tb, CsY2F7:Tb and KMgF3:Sm) in order to determine whether they can be used as real time dosimeters in the the framework the fiberoptic dosimetry (FOD) technique. This technique is based on the use of scintillating materials coupled to the end of an optical fiber, which collects the light emitted by the scintillator during irradiation. Since usually the intensity of the emitted light is proportional to the dose-rate, the technique provides a reliable measuring method, which can be employed in radiotherapy treatments.

Molina, P.; Santiago, M.; Marcassó, J.; Caselli, E.; Prokic, M.; Khaidukov, N.; Furetta, C.

2011-09-01

302

Reducing fitness costs associated with antibiotic resistance  

E-print Network

Reducing fitness costs associated with antibiotic resistance Experimental evolution Reducing fitness costs associated with antibiotic resistance Experimental evolution in the filamentous;Schoustra, Sijmen Ecco Reducing fitness costs associated with antibiotic resistance ­ Experimental evolution

Kassen, Rees

303

Current Issues in Flexibility Fitness.  

ERIC Educational Resources Information Center

Physical activity is extremely important in maintaining good health. Activity is not possible without a certain amount of flexibility. This report discusses issues related to flexibility fitness. Flexibility is a property of the musculoskeletal system that determines the range of motion achievable without injury to the joints. Static flexibility…

Knudson, Duane V.; Magnusson, Peter; McHugh, Malachy

2000-01-01

304

Color Coding Childrens' Fitness Performance.  

ERIC Educational Resources Information Center

A program of the Salt Lake City School District and the University of Utah, Operation C.H.A.M.P. (Children's Health and Movement Program), was designed to motivate elementary school children to do their best in physical education and fitness testing. The program is described. (MT)

West, Barbara H.; And Others

1987-01-01

305

Fitting Behaviors to Pedestrian Simulations  

Microsoft Academic Search

In this paper we present a data-driven approach for fitting behaviors to simulated pedestrian crowds. Our method annotates agent trajectories, generated by any crowd simulator, with action-tags. The aggregate effect of animating the agents according to the tagged trajectories enhances the impression that the agents are interacting with one another and with the environment. In a preprocessing stage, the stimuli

Alon Lerner; Eitan Fitusi; Yiorgos Chrysanthou; Daniel Cohen-Or

2009-01-01

306

Fitting Cosmological Data Baryon Model  

NSDL National Science Digital Library

The 1998 discovery of the cosmic acceleration with supernovae was recently awarded the 2011 Nobel Prize in Physics. Measurements of the baryon acoustic oscillations (BAO), as standard rulers, support this accelerated expansion of the universe (cosmic acceleration). The simulation allows users to compare and fit theoretical models of cosmology with recent BAO data sets to confirm the accelerated expansion of the universe. This modeling allows the user to vary cosmological parameters within a particular class of dark energy cosmological models to fit a particular cosmological data set. The user can plot several theoretical curves with the data to compare different models. The values of these parameters, for a particular model, determine the physical description and evolution of the universe. The Fitting Cosmological Data Baryon Model was created using Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_FittingCosmologicalDataBaryon.jar file will run the program if Java is installed. You can modify this simulation if you have EJS by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item.

Moldenhauer, Jacob; Stone, Keenan; Engelhardt, Larry

2012-09-07

307

Curve Fitting with Conic Splines  

Microsoft Academic Search

Conic splines are formed by arcs of conics, each defined by its endpoints and the tangents at them plus an intermediate point. Instead of the common general equation that depends on five parameters, an equation with a single parameter is used, thus simplifying significantly the curve fitting problem. The resulting guided conics resemble Bezier polynomials and for parabolas are identical

Theodosios Pavlidis

1983-01-01

308

When Knottiness is Fitting Behavior.  

ERIC Educational Resources Information Center

Describes a classroom activity based on the practice of fishermen tying knots in boat anchor ropes to determine river or lake depth. Knot-tying provides a simple hands-on context for students modeling in algebra. Students were actively involved in measuring, collecting data, fitting a line to data, finding an equation for a line, and checking a…

Fosnaugh, Linda S.; And Others

1997-01-01

309

Model Fitting in Particle Physics  

E-print Network

priors, and for both signs of µ. Discard first 2000 points as “ burn in”. Use Gelman-Rubin Rˆ test for convergence? demand r Bin data into 75× 75 bins for analysis. MCMC Fits to LVS Allanach, Dolan, Weber The Standard Model and Beyond From...

Dolan, Matthew

2008-06-27

310

Preparation of Police Fitness Instructors.  

ERIC Educational Resources Information Center

Concern about the declining level of physical fitness of police officers has led the Bureau of Training of the Kentucky Department of Justice and the Department of Physical Education at Eastern Kentucky University to implement a training course for police instructors. (LH)

Collingwood, Thomas R.; And Others

1979-01-01

311

Statistical evaluations in fitting problems.  

PubMed

The problem of error analysis is considered taking into account all possible correlations and a prior information about the accessible parameter space. Special attention is paid to the correct determination of the relative weight of experimental data and the a priori guess. The applications of statistical chi2- and F-tests to the fitting problems are also discussed. PMID:11512749

Klementev, K V

2001-03-01

312

Efficient Clothing Fitting from Data  

Microsoft Academic Search

A major drawback of shopping for clothes on-line is that the customer cannot try on clothes and see if they fit or suit them. One solution is to display clothing on an avatar, a 3D graphical model of the customer. However the normal technique for modeling clothing in computer graphics, cloth dynamics, suffers from being too processor intensive and is

Marco Gillies; Daniel Ballin; Balázs Csanád Csáji

2004-01-01

313

Physical Therapist Assistant Fitness Lab.  

ERIC Educational Resources Information Center

Colby Community College's (CCC) Fitness Lab was established to provide the Physical Therapist Assistant (PTA) Program with a learning laboratory in which students can practice classroom-acquired skills, while at the same time promoting the physical, emotional, social, and intellectual well-being of CCC students and staff, and community members. A…

Backstrom, Kurt; And Others

314

Fitting Cosmological Data Hz Model  

NSDL National Science Digital Library

The 1998 discovery of the cosmic acceleration with supernovae was recently awarded the 2011 Nobel Prize in Physics. Direct and indirect measurements of the Hubble Parameter, H(z), support this accelerated expansion of the universe (cosmic acceleration). The simulation allows users to compare and fit theoretical models of cosmology with recent Hubble Parameter data sets to confirm the accelerated expansion of the universe. This modeling allows the user to vary cosmological parameters within a particular class of dark energy cosmological models to fit a particular cosmological data set. The user can plot several theoretical curves with the data to compare different models. The values of these parameters, for a particular model, determine the physical description and evolution of the universe. The EJS Fitting Cosmological Data Hz Model was created using Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_FittingCosmologicalDataHz.jar file will run the program if Java is installed. You can modify this simulation if you have EJS by right-clicking within the plot and selecting Open Ejs Model from the pop-up menu item.

Moldenhauer, Jacob; Stone, Keenan; Engelhardt, Larry

2012-09-07

315

COGNITIVE FITNESS IN IMMERSIVE VIRTUAL  

E-print Network

of Language, Speech, and Brain Disorders · People with aphasia ­ focus on ICT · Master in ICT and Learning;Constructivistic view on knowledge and learning · Neuroconstructivistic view on the brain (Luria, Goldberg, FredensCOGNITIVE FITNESS IN IMMERSIVE VIRTUAL WORLDS - Designing a Learning Environment for People

Hansen, René Rydhof

316

Sports Potentials for Physical Fitness.  

ERIC Educational Resources Information Center

This report, one of a series on research into specific physical activities and their efficacy in improving and maintaining physical fitness, examines sport participation and the potential it has for developing muscular strength, muscular endurance, and circulatory-respiratory endurance. The activities consist primarily of the following twelve…

Clarke, H. Harrison, Ed.

1978-01-01

317

Fv: Interactive FITS file editor  

NASA Astrophysics Data System (ADS)

Fv is an easy-to-use graphical program for viewing and editing any FITS format image or table. The Fv software is small, completely self-contained and runs on Windows PCs, most Unix platforms and Mac OS-X. Fv also provides a portal into the Hera data analysis service from the HEASARC.

Pence, William; Chai, Pan

2012-05-01

318

Gel Electrophoresis Lab: DNA Fingerprinting  

NSDL National Science Digital Library

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators introduces the methods of RFLP analysis, or DNA fingerprinting, by using gel electrophoresis. Students will learn the role of restriction enzymes in DNA fingerprinting. Required materials, procedure and instructions are provided. This lesson plan may be downloaded in Microsoft Word document file format.

Ehlers, Megan

2012-10-24

319

Electromechanical coupling in polyelectrolyte gels  

Microsoft Academic Search

This work concerns the systematic characterization of the electromechanical coupling in polyelectrolyte gels (PGs) in correlation with their structure and physical properties in view of their potential application as pressure sensors. PGs are electroactive polymers that respond with an electrical potential difference to gradients in mechanical stress and vice versa. So far, these materials have mainly been studied as electrical

Katsiaryna I. Prudnikova

2010-01-01

320

Gluing gels: A nanoparticle solution  

NASA Astrophysics Data System (ADS)

Synthetic polymer gels with certain surface chemistries can be glued together by a simple and inexpensive method that uses commercially available silica nanoparticles. Biological tissues can also be joined by this nanotechnological route, eliminating the need for sutures, additional adhesives or chemical reactions.

Appel, Eric A.; Scherman, Oren A.

2014-03-01

321

Gel Electrophoresis Lab: Paternity Case  

NSDL National Science Digital Library

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators provides instructions for conducting a gel electrophoresis lab. Students will try to solve a paternity case with this activity by obtaining a DNA fingerprint from each potential father, the mother and the child. This activity may be downloaded in PDF file format. A data collection sheet and student questions are also included.

2013-07-05

322

Clinical radionuclide therapy dosimetry: the quest for the "Holy Gray"  

PubMed Central

Introduction Radionuclide therapy has distinct similarities to, but also profound differences from external radiotherapy. Review This review discusses techniques and results of previously developed dosimetry methods in thyroid carcinoma, neuro-endocrine tumours, solid tumours and lymphoma. In each case, emphasis is placed on the level of evidence and practical applicability. Although dosimetry has been of enormous value in the preclinical phase of radiopharmaceutical development, its clinical use to optimise administered activity on an individual patient basis has been less evident. In phase I and II trials, dosimetry may be considered an inherent part of therapy to establish the maximum tolerated dose and dose–response relationship. To prove that dosimetry-based radionuclide therapy is of additional benefit over fixed dosing or dosing per kilogram body weight, prospective randomised phase III trials with appropriate end points have to be undertaken. Data in the literature which underscore the potential of dosimetry to avoid under- and overdosing and to standardise radionuclide therapy methods internationally are very scarce. Developments In each section, particular developments and insights into these therapies are related to opportunities for dosimetry. The recent developments in PET and PET/CT imaging, including micro-devices for animal research, and molecular medicine provide major challenges for innovative therapy and dosimetry techniques. Furthermore, the increasing scientific interest in the radiobiological features specific to radionuclide therapy will advance our ability to administer this treatment modality optimally. PMID:17268773

Bodei, L.; Giammarile, F.; Linden, O.; Luster, M.; Oyen, W. J. G.; Tennvall, J.

2007-01-01

323

Capillary fracture of soft gels.  

PubMed

A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact line in a starburst pattern. In this paper, we characterize (i) the initiation process, in which the number of arms in the starburst is controlled by the ratio of the surface tension contrast to the gel's elastic modulus, and (ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law L[proportional]t(3/4). We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid-solid wetting forces. The elastic solution shows that both the location and the magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an important factor in the fracture process, as it can help mitigate large surface tractions; this finding is confirmed with experiments. We then develop a model for crack propagation by considering the transport of an inviscid fluid into the fracture tip of an incompressible material and find that a simple energy-conservation argument can explain the observed material-independent power law. We compare predictions for both linear elastic and neo-Hookean solids, finding that the latter better explains the observed exponent. PMID:24229192

Bostwick, Joshua B; Daniels, Karen E

2013-10-01

324

Effect of processor temperature on film dosimetry  

SciTech Connect

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

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

2012-07-01

325

Radiotherapy dosimetry using a commercial OSL system  

SciTech Connect

A commercial optically stimulated luminescence (OSL) system developed for radiation protection dosimetry by Landauer, Inc., the InLight microStar reader, was tested for dosimetry procedures in radiotherapy. The system uses carbon-doped aluminum oxide, Al{sub 2}O{sub 3}:C, as a radiation detector material. Using this OSL system, a percent depth dose curve for {sup 60}Co gamma radiation was measured in solid water. Field size and SSD dependences of the detector response were also evaluated. The dose response relationship was investigated between 25 and 400 cGy. The decay of the response with time following irradiation and the energy dependence of the Al{sub 2}O{sub 3}:C OSL detectors were also measured. The results obtained using OSL dosimeters show good agreement with ionization chamber and diode measurements carried out under the same conditions. Reproducibility studies show that the response of the OSL system to repeated exposures is 2.5% (1sd), indicating a real possibility of applying the Landauer OSL commercial system for radiotherapy dosimetric procedures.

Viamonte, A.; Rosa, L. A. R. da; Buckley, L. A.; Cherpak, A.; Cygler, J. E. [Programa de Qualidade em Radioterapia, Instituto Nacional de Cancer (INCA/MS), Rua do Resende 128 3 Andar. Centro. Rio de Janeiro, CEP: 20231-092, Rio de Janeiro (Brazil) and Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box: 68509, 21941-972, Rio de Janeiro (Brazil); Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, Rio de Janeiro, CEP: 22780-160, Rio de Janeiro (Brazil); Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd., Ottawa, Ontario K1H 1C4 (Canada); Department of Medical Physics, Ottawa Hospital Regional Cancer Centre, 503 Smyth Rd. Ottawa, Ontario K1H 1C4 (Canada) and Physics Department, Carleton University, 1125 Colonel By Dr., Ottawa, Ontario K1S 5B6 (Canada)

2008-04-15

326

Exit dose measurements by portal film dosimetry.  

PubMed

Portal in vivo dosimetry is a very attractive tool for patient dose measurements because of the large amount of information that portal film systems can easily collect, once positioned at the exit surface of the patient. The first step in the verification of the reliability of portal films as in vivo dosimeters is the evaluation of the agreement between exit patient dose profiles and optical density profiles measured on the portal film. We checked the possibilities for exit dose measurements of a commercial portal film system (Film Kodak X-Omat V and Localization Kodak Cassette) verifying the agreement between relative exit doses (measured by ionization chamber and film dosimetry, calculated by our treatment planning system (Cadplan Dosetek)) and relative optical densities on portal films in cubic homogeneous and inhomogeneous, cylindrical and humanoid phantoms. In particular, a good agreement (mean difference in absolute value: 2%) between optical densities and calculated exit doses for the Rando phantom were found, once the optical densities values are corrected for an inverse square correction factor, taking into account the variation of the profile of the phantom. PMID:8127984

Fiorino, C; del Vecchio, A; Cattaneo, G M; Fusca, M; Longobardi, B; Signorotto, P; Calandrino, R

1993-12-01

327

Internal dosimetry verification and validation database.  

PubMed

Simulated-data internal dosimetry cases for use in intercomparison exercises or as a software verification and validation tool have been published on the internet (www.lanl.gov/bayesian/software Bayesian software package II). A user may validate their internal dosimetry code or method using this simulated bioassay data. Or, the user may choose to try out the Los Alamos National Laboratory codes ID and UF, which are also supplied. A Poisson-lognormal model of data uncertainty is assumed. A collection of different possible models for each nuclide (e.g. solubility types and particle sizes) are used. For example, for 238Pu, 14 different biokinetic models or types (8 inhalation, 4 wound and 2 ingestion) are assumed. Simulated data are generated for all the assumed biokinetic models, both for incidents, where the time of intake is known, and for non-incidents, where it is not. For the dose calculations, the route of intake, but not the biokinetic model, is considered to be known. The object is to correctly calculate the known true dose from simulated data covering a period of time. A 'correct' result has been defined in two ways: (1) that the credible limits of the calculated dose include the correct dose and (2) that the calculated dose is within a factor of 2 of the correct dose. PMID:18325930

Miller, G; Bertelli, L; Little, T; Guilmette, R A

2007-01-01

328

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

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

Rathbone, Bruce A.

2009-08-28

329

A Person-Environment Fit Approach to Volunteerism: Volunteer Personality Fit and Culture Fit as Predictors of Affective Outcomes  

Microsoft Academic Search

This study employed a person-environment (P-E) fit approach to explaining volunteer satisfaction, affective commitment, and turnover intentions. It was hypothesized that personality fit would explain additional variance in volunteer affective outcomes above and beyond motives to volunteer. This hypothesis was supported. Personality fit but not culture fit was related to satisfaction and affective commitment. Volunteer turnover intentions were predicted by

Annelies E. M. Van Vianen; Bernard A. Nijstad; Olga F. Voskuijl

2008-01-01

330

Commercial applications of block copolymer photonic gels  

E-print Network

Block copolymer photonic gels are a simple and easily processed material which responds rapidly to environmental stimuli through a color change. The diblock copolymer that forms the gel self-assembles into a lamellar ...

Lou, Sally S

2008-01-01

331

On the calibration process of film dosimetry: OLS inverse regression versus WLS inverse prediction  

NASA Astrophysics Data System (ADS)

The purpose of this study was both putting forward a statistically correct model for film calibration and the optimization of this process. A reliable calibration is needed in order to perform accurate reference dosimetry with radiographic (Gafchromic) film. Sometimes, an ordinary least squares simple linear (in the parameters) regression is applied to the dose-optical-density (OD) curve with the dose as a function of OD (inverse regression) or sometimes OD as a function of dose (inverse prediction). The application of a simple linear regression fit is an invalid method because heteroscedasticity of the data is not taken into account. This could lead to erroneous results originating from the calibration process itself and thus to a lower accuracy. In this work, we compare the ordinary least squares (OLS) inverse regression method with the correct weighted least squares (WLS) inverse prediction method to create calibration curves. We found that the OLS inverse regression method could lead to a prediction bias of up to 7.3 cGy at 300 cGy and total prediction errors of 3% or more for Gafchromic EBT film. Application of the WLS inverse prediction method resulted in a maximum prediction bias of 1.4 cGy and total prediction errors below 2% in a 0-400 cGy range. We developed a Monte-Carlo-based process to optimize calibrations, depending on the needs of the experiment. This type of thorough analysis can lead to a higher accuracy for film dosimetry.

Crop, F.; Van Rompaye, B.; Paelinck, L.; Vakaet, L.; Thierens, H.; DeWagter, C.

2008-07-01

332

Dosimetry of Auger emitters: Physical and phenomenological approaches  

SciTech Connect

Recent radiobiological studies have demonstrated that Auger cascades can cause severe biological damage contrary to expectations based on conventional dosimetry. Several determinants govern these effects, including the nature of the Auger electron spectrum; localized energy deposition; cellular geometry; chemical form of the carrier; cellular localization, concentration, and subcellular distribution of the radionuclide. Conventional dosimetry is inadequate in that these considerations are ignored. Our results provide the basis for biophysical approaches toward subcellular dosimetry of Auger emitters in vitro and in vivo. 12 refs., 7 figs., 2 tabs.

Sastry, K.S.R.; Howell, R.W.; Rao, D.V.; Mylavarapu, V.B.; Kassis, A.I.; Adelstein, S.J.; Wright, H.A.; Hamm, R.N.; Turner, J.E.

1987-01-01

333

Frictional properties of high functional gel materials  

NASA Astrophysics Data System (ADS)

The frictional behavior of the four kinds of high functional gels, which are double network (DN) gels, particle-double network gels (P-DN), shape memory gels (SMG), LA-shape memory gels (LA-SMG) and was studied. The velocity dependence looks similar for both the DN gels and the SMG, however the details of the dependence are different. The coefficient of the DN gels is smaller than that of the SMGs. The coefficient decreases as the normal force increases. This normal force dependence was observed for the DN gels previously, however for the first time for the SMGs. The velocity dependence looks similar for both the DN gels and the SMG, however the details of the dependence are different. The coefficient of the DN gels is smaller than that of the SMGs. The difference of the dependences is possibly related to the different softness by the temperature change of the gels. The temperature dependence of the coefficient of friction in LA-SMG was observed. Increase of the perpendicular load and the surface softness were influenced by coefficient of friction increase. In addition, the frictional coefficient of P-DN that different particle size was measured for the first time. The difference of the friction behavior of LA-SMG by the particle size was clear. Therefore, we show frictional coefficient of various high functional gels.

Wada, Masato; Yamada, Kohei; Yamada, Naoya; Makino, Masato; Gong, Jin; Furukawa, Hidemitsu

2014-03-01

334

Gel phantom in selective laser phototherapy  

Microsoft Academic Search

Tissue-simulating gel phantoms have been used in selective laser photothermal interaction. The gelatin phantom provides a uniform tissue-simulating medium for analyzing thermal performance under laser radiation. The gelatin phantom gel is used particularly in measurements of thermal reactions in laser thermology. The gelatin phantom is made from gelatin and Liposyn. A special gel sphere with Indocyanine Green (ICG) laser absorption

Yichao Chen; Christopher A. Bailey; Thomas M. Cowan; Feng Wu; Hong Liu; Rheal A. Towner; Wei R. Chen

2008-01-01

335

Radiological properties of normoxic polymer gel dosimeters  

Microsoft Academic Search

The radiological properties of the normoxic polymer gel dosimeters MAGIC, MAGAS, and MAGAT [methacrylic and ascorbic acid in gelatin initiated by copper; methacrylic acid gelatine gel with ascorbic acid; and methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride, respectively] have been investigated. The radiological water equivalence was determined by comparing the polymer gel macroscopic photon and electron interaction cross sections

A. J. Venning; K. N. Nitschke; P. J. Keall; C. Baldock

2005-01-01

336

Spring-loaded polymeric gel actuators  

DOEpatents

Spring-loaded electrically controllable polymeric gel actuators are disclosed. The polymeric gels can be polyvinyl alcohol, polyacrylic acid, or polyacrylamide, and are contained in an electrolytic solvent bath such as water plus acetone. The action of the gel is mechanically biased, allowing the expansive and contractile forces to be optimized for specific applications.

Shahinpoor, Mohsen (Albuquerque, NM)

1995-01-01

337

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

338

Physical Activity and Cardiorespiratory Fitness  

Microsoft Academic Search

Physical inactive adults have higher incidence of cardiovascular and total mortality. Unfit subjects tend also to have higher\\u000a mortality rates. The metabolic syndrome increases with age and tends to increase cardiovascular mortality. Higher levels of\\u000a physical activity and cardiorespiratory fitness in children, adolescents, and adults improve metabolic syndrome features.\\u000a Current physical activity guidelines for children, adolescents and adults lack evidence-based

Luís Bettencourt Sardinha

339

Cumulative irritation potential among metronidazole gel 1%, metronidazole gel 0.75%, and azelaic acid gel 15%.  

PubMed

Topical therapy for rosacea aims to reduce inflammatory lesions and decrease erythema but can carry side effects such as stinging, pruritus, and burning. Metronidazole and azelaic acid gel 15% are U.S. Food and Drug Administration-approved for the treatment of rosacea. The current study was conducted to assess the cumulative irritation potential of 2 formulations of metronidazole 0.75% gel and 1% gel--and azelaic acid gel 15% over 21 days (N=36). Results of this study demonstrated a significantly greater poten tial for irritation from azelaic acid compared with metronidazole gel 0.75% (P < .0001), which had significantly greater potential for irritation compared with metronidazole gel 1% (P = .0054). Metronidazole gel 1% had a similar profile to white petrolatum. PMID:17500380

Colón, Luz E; Johnson, Lori A; Gottschalk, Ronald W

2007-04-01

340

Permanent Breast Seed Implant Dosimetry Quality Assurance  

SciTech Connect

Purpose: A permanent breast seed implant is a novel method of accelerated partial breast irradiation for women with early-stage breast cancer. This article presents pre- and post-implant dosimetric data, relates these data to clinical outcomes, and makes recommendations for those interested in starting a program. Methods and Materials: A total of 95 consecutive patients were accrued into one of three clinical trials after breast-conserving surgery: a Phase I/II trial (67 patients with infiltrating ductal carcinoma); a Phase II registry trial (25 patients with infiltrating ductal carcinoma); or a multi-center Phase II trial for patients with ductal carcinoma in situ (3 patients). Contouring of the planning target volume (PTV) was done on a Pinnacle workstation and dosimetry calculations, including dose-volume histograms, were done using a Variseed planning computer. Results: The mean pre-implant PTV coverage for the V{sub 90}, V{sub 100}, V{sub 150}, and V{sub 200} were as follows: 98.8% {+-} 1.2% (range, 94.5-100%); 97.3% {+-} 2.1% (range, 90.3-99.9%), 68.8% {+-} 14.3% (range, 32.7-91.5%); and 27.8% {+-} 8.6% (range, 15.1-62.3%). The effect of seed motion was characterized by post-implant dosimetry performed immediately after the implantation (same day) and at 2 months after the implantation. The mean V{sub 100} changed from 85.6% to 88.4% (p = 0.004) and the mean V{sub 200} changed from 36.2% to 48.3% (p < 0.001). Skin toxicity was associated with maximum skin dose (p = 0.014). Conclusions: Preplanning dosimetry should aim for a V{sub 90} of approximately 100%, a V{sub 100} between 95% and 100%, and a V{sub 200} between 20% and 30%, as these numbers are associated with no local recurrences to date and good patient tolerance. In general, the target volume coverage improved over the duration of the seed therapy. The maximum skin dose, defined as the average dose over the hottest 1 Multiplication-Sign 1-cm{sup 2} surface area, should be limited to 90% of the prescription dose to minimize delayed skin toxicity.

Keller, Brian M., E-mail: Brian.Keller@sunnybrook.ca [Department of Medical Physics, Sunnybrook Health Sciences Center, Toronto, ON (Canada); Department of Radiation Oncology, University of Toronto, Sunnybrook Health Sciences Center, Toronto, ON (Canada); Ravi, Ananth [Department of Medical Physics, Sunnybrook Health Sciences Center, Toronto, ON (Canada); Sankreacha, Raxa [Carlo Fidani Regional Cancer Center, Mississauga, ON (Canada); Pignol, Jean-Philippe [Department of Radiation Oncology, University of Toronto, Sunnybrook Health Sciences Center, Toronto, ON (Canada)

2012-05-01

341

A Quantitative Fitness Analysis Workflow  

PubMed Central

Quantitative Fitness Analysis (QFA) is an experimental and computational workflow for comparing fitnesses of microbial cultures grown in parallel1,2,3,4. QFA can be applied to focused observations of single cultures but is most useful for genome-wide genetic interaction or drug screens investigating up to thousands of independent cultures. The central experimental method is the inoculation of independent, dilute liquid microbial cultures onto solid agar plates which are incubated and regularly photographed. Photographs from each time-point are analyzed, producing quantitative cell density estimates, which are used to construct growth curves, allowing quantitative fitness measures to be derived. Culture fitnesses can be compared to quantify and rank genetic interaction strengths or drug sensitivities. The effect on culture fitness of any treatments added into substrate agar (e.g. small molecules, antibiotics or nutrients) or applied to plates externally (e.g. UV irradiation, temperature) can be quantified by QFA. The QFA workflow produces growth rate estimates analogous to those obtained by spectrophotometric measurement of parallel liquid cultures in 96-well or 200-well plate readers. Importantly, QFA has significantly higher throughput compared with such methods. QFA cultures grow on a solid agar surface and are therefore well aerated during growth without the need for stirring or shaking. QFA throughput is not as high as that of some Synthetic Genetic Array (SGA) screening methods5,6. However, since QFA cultures are heavily diluted before being inoculated onto agar, QFA can capture more complete growth curves, including exponential and saturation phases3. For example, growth curve observations allow culture doubling times to be estimated directly with high precision, as discussed previously1. Here we present a specific QFA protocol applied to thousands of S. cerevisiae cultures which are automatically handled by robots during inoculation, incubation and imaging. Any of these automated steps can be replaced by an equivalent, manual procedure, with an associated reduction in throughput, and we also present a lower throughput manual protocol. The same QFA software tools can be applied to images captured in either workflow. We have extensive experience applying QFA to cultures of the budding yeast S. cerevisiae but we expect that QFA will prove equally useful for examining cultures of the fission yeast S. pombe and bacterial cultures. PMID:22907268

Lydall, D.A.

2012-01-01

342

10 CFR 35.2630 - Records of dosimetry equipment used with remote afterloader units, teletherapy units, and gamma...  

... 2014-01-01 false Records of dosimetry equipment used with remote afterloader... Records § 35.2630 Records of dosimetry equipment used with remote afterloader...intercomparison, and comparisons of its dosimetry equipment done in accordance...

2014-01-01

343

10 CFR 35.2630 - Records of dosimetry equipment used with remote afterloader units, teletherapy units, and gamma...  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 false Records of dosimetry equipment used with remote afterloader... Records § 35.2630 Records of dosimetry equipment used with remote afterloader...intercomparison, and comparisons of its dosimetry equipment done in accordance...

2011-01-01

344

10 CFR 35.2630 - Records of dosimetry equipment used with remote afterloader units, teletherapy units, and gamma...  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 false Records of dosimetry equipment used with remote afterloader... Records § 35.2630 Records of dosimetry equipment used with remote afterloader...intercomparison, and comparisons of its dosimetry equipment done in accordance...

2012-01-01

345

10 CFR 35.2630 - Records of dosimetry equipment used with remote afterloader units, teletherapy units, and gamma...  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Records of dosimetry equipment used with remote afterloader... Records § 35.2630 Records of dosimetry equipment used with remote afterloader...intercomparison, and comparisons of its dosimetry equipment done in accordance...

2010-01-01

346

10 CFR 35.2630 - Records of dosimetry equipment used with remote afterloader units, teletherapy units, and gamma...  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 false Records of dosimetry equipment used with remote afterloader... Records § 35.2630 Records of dosimetry equipment used with remote afterloader...intercomparison, and comparisons of its dosimetry equipment done in accordance...

2013-01-01

347

Structural change of ?-carrageenan gel near sol-gel transition point  

NASA Astrophysics Data System (ADS)

The structural change of ?-carrageenan gel in the gel-to-sol transition was observed with the small-angle neutron scattering (SANS). The SANS intensity decreases on approaching to the transition point from the gel phase. On the other hand, the observed gyration radius does not change in the whole region of the gel phase. The fact means that the number of the cross link points decreases but their size keeps almost unchanged in the gel-to-sol transition.

Masaaki Sugiyama; Chikanori Yuasa; Kazuhiro Hara; Nobuyasu Hiramatsu; Atsushi Nakamura; Yasushi Hayakawa; Yutaka Maeda

348

Retrospective dosimetry analyses of reactor vessel cladding samples  

SciTech Connect

Reactor pressure vessel cladding samples for Ringhals Units 3 and 4 in Sweden were analyzed using retrospective reactor dosimetry techniques. The objective was to provide the best estimates of the neutron fluence for comparison with neutron transport calculations. A total of 51 stainless steel samples consisting of chips weighing approximately 100 to 200 mg were removed from selected locations around the pressure vessel and were sent to Pacific Northwest National Laboratory for analysis. The samples were fully characterized and analyzed for radioactive isotopes, with special interest in the presence of Nb-93m. The RPV cladding retrospective dosimetry results will be combined with a re-evaluation of the surveillance capsule dosimetry and with ex-vessel neutron dosimetry results to form a comprehensive 3D comparison of measurements to calculations performed with 3D deterministic transport code. (authors)

Greenwood, L. R.; Soderquist, C. Z. [Battelle Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Fero, A. H. [Westinghouse Electric Company, Cranberry Twp., PA 16066 (United States)

2011-07-01

349

DOSIMETRY OF OZONE AND NITROGEN DIOXIDE IN MAN AND ANIMALS  

EPA Science Inventory

Agreement between experimental data on maximum morphological damage and maximal predicated tissue does offers promise that mathematical dosimetry models can contribute to a better understanding of effective doses in animal studies and their correspondence to human exposure levels...

350

Software for evaluation of EPR-dosimetry performance.  

PubMed

Electron paramagnetic resonance (EPR) with tooth enamel is a method extensively used for retrospective external dosimetry. Different research groups apply different equipment, sample preparation procedures and spectrum processing algorithms for EPR dosimetry. A uniform algorithm for description and comparison of performances was designed and implemented in a new computer code. The aim of the paper is to introduce the new software 'EPR-dosimetry performance'. The computer code is a user-friendly tool for providing a full description of method-specific capabilities of EPR tooth dosimetry, from metrological characteristics to practical limitations in applications. The software designed for scientists and engineers has several applications, including support of method calibration by evaluation of calibration parameters, evaluation of critical value and detection limit for registration of radiation-induced signal amplitude, estimation of critical value and detection limit for dose evaluation, estimation of minimal detectable value for anthropogenic dose assessment and description of method uncertainty. PMID:24876337

Shishkina, E A; Timofeev, Yu S; Ivanov, D V

2014-06-01

351

Review of retrospective dosimetry techniques for external ionising radiation exposures.  

PubMed

The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements. PMID:21183550

Ainsbury, E A; Bakhanova, E; Barquinero, J F; Brai, M; Chumak, V; Correcher, V; Darroudi, F; Fattibene, P; Gruel, G; Guclu, I; Horn, S; Jaworska, A; Kulka, U; Lindholm, C; Lloyd, D; Longo, A; Marrale, M; Monteiro Gil, O; Oestreicher, U; Pajic, J; Rakic, B; Romm, H; Trompier, F; Veronese, I; Voisin, P; Vral, A; Whitehouse, C A; Wieser, A; Woda, C; Wojcik, A; Rothkamm, K

2011-11-01

352

Proceedings of the third conference on radiation protection and dosimetry  

SciTech Connect

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

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

1991-10-01

353

Demonstration of the solar gel pond  

NASA Astrophysics Data System (ADS)

Viscous polymeric gels that act as a thermal insulator and produce high energy collection and storage efficiencies were deveoped. These polymer gels were tested in a small-scale solar pond. The highest bottom temperature was achieved with the bottom layer filled with a salt solution and covered with a top layer of 16 cm polymer gel. By covering the gel layer with a thin layer of water, dirt and debris falling onto the pond can be skimmed, and evaporation can be retarded. The highest bottom temperature and satisfactory efficiency (72%) were obtained with the addition of a gel layer 16 cm thick as an insulation on the top of the saline.

Wilkins, E. S.

1981-07-01

354

Trabecular bone dosimetry using a Monte Carlo code  

E-print Network

TRABECULAR BONE DOSIMETRY USING A MONTE CARLO CODE by ANNE ZUZARTE DE MENDONCA Submitted to the Office of Graduate Studies of Texas Ad'tM University in partial fulfillement of the requirements for the degree of MASTER OF SCIENCE August 1993... Major Subject: Nuclear Engineering TRABECULAR BONE DOSIMETRY USING A MONTE CARLO CODE A thesis by ANNE ZUZARTE DE ~NCA Submitted to Texas AdtM University in partial fulfillement of the requirements for the degree of MASTER OF SCIENCE Approved...

Zuzarte de Mendonca, Anne

2012-06-07

355

Dosimetry and Temperature Aspects of Mobile-Phone Exposures  

Microsoft Academic Search

\\u000a Dosimetric assessment is an import subject in studying the effects from exposure to wireless communication devices. It provides\\u000a a quantitative measure for epidemiological studies and in the development of exposure guidelines. Dosimetry may be accomplished\\u000a either numerically or experimentally, or by a combination of both since each technique has its own advantages and drawbacks.\\u000a While numerical dosimetry forms the focus

Paolo Bernardi; Stefano Pisa; Marta Cavagnaro; Emanuel Piuzzi; James C. Lin

356

EPID dosimetry for pretreatment quality assurance with two commercial systems.  

PubMed

This study compares the EPID dosimetry algorithms of two commercial systems for pretreatment QA, and analyzes dosimetric measurements made with each system alongside the results obtained with a standard diode array. 126 IMRT fields are examined with both EPID dosimetry systems (EPIDose by Sun Nuclear Corporation, Melbourne FL, and Portal Dosimetry by Varian Medical Systems, Palo Alto CA) and the diode array, MapCHECK (also by Sun Nuclear Corporation). Twenty-six VMAT arcs of varying modulation complexity are examined with the EPIDose and MapCHECK systems. Optimization and commissioning testing of the EPIDose physics model is detailed. Each EPID IMRT QA system is tested for sensitivity to critical TPS beam model errors. Absolute dose gamma evaluation (3%, 3 mm, 10% threshold, global normalization to the maximum measured dose) yields similar results (within 1%-2%) for all three dosimetry modalities, except in the case of off-axis breast tangents. For these off-axis fields, the Portal Dosimetry system does not adequately model EPID response, though a previously-published correction algorithm improves performance. Both MapCHECK and EPIDose are found to yield good results for VMAT QA, though limitations are discussed. Both the Portal Dosimetry and EPIDose algorithms, though distinctly different, yield similar results for the majority of clinical IMRT cases, in close agreement with a standard diode array. Portal dose image prediction may overlook errors in beam modeling beyond the calculation of the actual fluence, while MapCHECK and EPIDose include verification of the dose calculation algorithm, albeit in simplified phantom conditions (and with limited data density in the case of the MapCHECK detector). Unlike the commercial Portal Dosimetry package, the EPIDose algorithm (when sufficiently optimized) allows accurate analysis of EPID response for off-axis, asymmetric fields, and for orthogonal VMAT QA. Other forms of QA are necessary to supplement the limitations of the Portal Vision Dosimetry system. PMID:22766944

Bailey, Daniel W; Kumaraswamy, Lalith; Bakhtiari, Mohammad; Malhotra, Harish K; Podgorsak, Matthew B

2012-01-01

357

Dosimetry for the approval of food irradiation processes  

NASA Astrophysics Data System (ADS)

The use of accurate and precise radiation dosimetry to control the food irradiation process for regulatory purposes is discussed. The various procedures required to establish a thorough dosimetric control, such as commissioning the irradiation facility, process validation and routine control are described. It is concluded that, coupled with an administrative inventory control, dosimetry can provide the guarantee that the process has been correctly applied and regulatory release of irradiated food can be based on accurate and reproducible absorbed dose measurements.

Miller, A.; Chadwick, K. H.

358

Reference dosimetry for various Health Physics Research Reactor spectra  

Microsoft Academic Search

Reference neutron dosimetry is developed in a consistent and reproducible manner for five different Health Physics Research Reactor (HPRR) spectra: the unshielded HPRR, the HPRR shielded by 20-cm concrete, by 12-cm Lucite, by 13-m steel, and by a 5-cm steel\\/15-cm concrete shield. The reference dosimetry is presented in two forms so as to be of maximum usefulness both to dosimetrists

C. S. Sims; G. G. Killough

1981-01-01

359

Sodium dodecyl sulfate micelles in polyacrylamide gels.  

NASA Astrophysics Data System (ADS)

Polyacrylamide gels have been made in the presence of sodium dodecyl sulfate (SDS) micelles. The use of these gels for electrophoresis, after removal of the SDS, has demonstrated that the micelles modify the internal gel structure(R. Rill, B. Locke, Y. Liu, J. Dharia, D Van Winkle, Electrophoresis 17), 1304 (1996).. The phase diagram of SDS in buffer exhibits several transitions as a function of concentration and ionic strength. The SDS concentration used for templating gels is quite high, on the order of 20 - 30% by weight. This is the range in which the micellar system undergoes phase transitions. X-ray and light scattering experiments on gels with and without SDS and in SDS-buffer solutions were performed to understand the structure of the templated pores left after SDS removal. These experiments indicate the characteristic length scales associated with SDS micelles in gels changes from 3 to 15 nm as the gel and the SDS concentrations are varied.

van Winkle, David H.; Kettwig, Franz; Rill, Randolph L.; Liu, Yingjie; Locke, Bruce R.

1997-03-01

360

Novel approaches in radon and thoron dosimetry  

NASA Astrophysics Data System (ADS)

This report presents some novel approaches for radon/radon progeny and thoron measurements that can help to resolve some long-lasting problems in dosimetry, but which are not yet part of the common practice. The focus is in two directions: The use of CDs/DVDs as radon and thoron detectors and the employment of grab-sampling and/or integrated radon progeny measurements for diagnostic of the air conditions related to mitigation and indoor ventilation. The potential of these approaches is illustrated by several successful applications: (1) Study of the 222Rn distribution in large buildings and identification of places with radon problem; (2) Radon and thoron monitoring in underground mines; (3) Radon measurements in natural waters, including directly in the water source; (4) Grab sampling 222Rn progeny measurements for the purposes of pre- and post-mitigation diagnostic; (5) Integrated measurements of individual 222Rn short-lived decay products for diagnostic of indoor ventilation conditions.

Pressyanov, D.; Dimitrov, D.; Dimitrova, I.; Georgiev, S.; Mitev, K.

2014-07-01

361

Accidental neutron dosimetry with human hair  

NASA Astrophysics Data System (ADS)

Human hair contains sulfur, which can be activated by fast neutrons. The 32S(n,p)32P reaction with a threshold of 2.5 MeV was used for fast neutron dose estimation. It is a very important parameter for individual dose reconstruction with regards to the heterogeneity of the neutron transfer to the human body. Samples of human hair were irradiated in a radial channel of a training reactor VR-1. 32P activity in hair was measured both, directly by means of a proportional counter, and as ash dispersed in a liquid scintillator. Based on neutron spectrum estimation, a relationship between the neutron dose and induced activity was derived. The experiment verified the practical feasibility of this dosimetry method in cases of criticality accidents or malevolent acts with nuclear materials.

Ekendahl, Daniela; Be?ková, V?ra; Zdychová, Vlasta; Bulánek, Boris; Prouza, Zden?k; Štefánik, Milan

2014-11-01

362

Fiber optic radiation dosimetry for medical applications  

NASA Astrophysics Data System (ADS)

The dosimetry with glass fibers perrilits for the first time the dose to be determined in the immediate vicinity of the tumour. A fiberoptic dosimeter can either be introduced during an operation or else inserted via a cannula into the vicinity of the tumour to be irradiated. The dosimeter should remain in the patient's body until radiation therapy has been completed. The basic principle of the fiberoptic dosimeter is to measure the additional attenuation generated in the fiber by irradiation. A lead-glass fiber with 60 weight - % PbO was used as a particular radiationsensitive fiber. This is a step-index fiber with a core diameter of 100 pm and a total diameter of 110 pm. Measurements of the spectral distribution of the induced loss result in a detection sensitivity of smaller than 0.1 Gy for the lead-glass fiber at a local resolution of about 2 cm. This satisfies the demands of radiotherapy.

Bueker, Harald; Haesing, Friedrich W.; Nicolai, S.; Wolters, B.

1990-07-01

363

Implications of ISO 9000 for personnel dosimetry  

SciTech Connect

Landauer, Inc. has gained approval to provide personnel dosimetry services in several countries. Each experiene reflects the different concerns adopted by national approval agencies. None have adopted ISO 9000 registration as evidence of a suitable quality system of management. Instead, each organization has prepared its own set of requirements with no provisions for recognizing the results of performance tests or audits conducted by other approval organizations. As ISO 9000 has become a communication symbol for commercial organizations dealing with each other, it has not been similarly viewed by radiation regulation bodies. A key reason arises from a tradition to regulate bodies. A key reason arises from a tradition to regulate, not promote, international trade, not encourage innovation, nor foster economic competition. A second reason is the inability to separate the technical requirements from quality assurance. ISO 9000 may become useful once the national technical organizations learn to trust those of other countries.

Yoder, R.C.

1995-12-31

364

Liulin-type spectrometry-dosimetry instruments.  

PubMed

The main purpose of Liulin-type spectrometry-dosimetry instruments (LSDIs) is cosmic radiation monitoring at the workplaces. An LSDI functionally is a low mass, low power consumption or battery-operated dosemeter. LSDIs were calibrated in a wide range of radiation fields, including radiation sources, proton and heavy-ion accelerators and CERN-EC high-energy reference field. Since 2000, LSDIs have been used in the scientific programmes of four manned space flights on the American Laboratory and ESA Columbus modules and on the Russian segment of the International Space Station, one Moon spacecraft and three spacecraft around the Earth, one rocket, two balloons and many aircraft flights. In addition to relative low price, LSDIs have proved their ability to qualify the radiation field on the ground and on the above-mentioned carriers. PMID:21177270

Dachev, Ts; Dimitrov, Pl; Tomov, B; Matviichuk, Yu; Spurny, F; Ploc, O; Brabcova, K; Jadrnickova, I

2011-03-01

365

A physical dosimetry intercomparison for BNCT.  

PubMed

An intercomparison of physical dosimetry methods used at the Massachusetts Institute of Technology (MIT) and Brookhaven National Laboratory was completed to enable retrospective analysis of BNCT trials. Measurements were performed under reference conditions pertinent to clinical irradiations at the epithermal neutron beam facility of the Brookhaven Medical Research Reactor (BMRR) using procedures developed at MIT during similar trials. Thermal neutron flux was determined from gold foil activation experiments and good agreement was found between the depth profiles measured in-phantom by the two groups. At a depth of 3.5 cm where the measured flux is greatest, the ratio of the MIT/BMRR measurements is 1.01+/-0.10 if the same reporting procedures are applied. Photon and fast neutron absorbed dose rates were assessed using ionization chambers with separate graphite and A-150 plastic walls. Measurement of the in-phantom photon depth dose component agreed favorably with that previously reported by the BMRR group using thermoluminescent dosimeters. At a depth of 3.5 cm the ratio of the MIT measurements to those made by the BMRR group was 0.89+/-0.12. In-air measurements of the fast neutron and photon absorbed dose rates agreed within the limits of experimental uncertainty. Additional studies were performed in the ellipsoidal water phantom regularly used for beam characterizations at MIT. No significant differences in the thermal neutron flux measured in either a solid PMMA cube or an ellipsoidal shaped water phantom were observed on the central axis of the beam. This study confirms the reproducibility and uniformity of dosimetry measurements performed by the two independent groups undertaking BNCT trials in the USA and provides the physical data necessary to compare BMRR treatment protocols with those applied at Harvard-MIT. PMID:12033586

Riley, Kent J; Binns, Peter J; Greenberg, Dennis D; Harling, Otto K

2002-05-01

366

Specific issues in small animal dosimetry and irradiator calibration  

PubMed Central

Purpose In response to the increased risk of radiological terrorist attack, a network of Centers for Medical Countermeasures against Radiation (CMCR) has been established in the United States, focusing on evaluating animal model responses to uniform, relatively homogenous whole- or partial-body radiation exposures at relatively high dose rates. The success of such studies is dependent not only on robust animal models but on accurate and reproducible dosimetry within and across CMCR. To address this issue, the Education and Training Core of the Duke University School of Medicine CMCR organised a one-day workshop on small animal dosimetry. Topics included accuracy in animal dosimetry accuracy, characteristics and differences of cesium-137 and X-ray irradiators, methods for dose measurement, and design of experimental irradiation geometries for uniform dose distributions. This paper summarises the information presented and discussed. Conclusions Without ensuring accurate and reproducible dosimetry the development and assessment of the efficacy of putative countermeasures will not prove successful. Radiation physics support is needed, but is often the weakest link in the small animal dosimetry chain. We recommend: (i) A user training program for new irradiator users, (ii) subsequent training updates, and (iii) the establishment of a national small animal dosimetry center for all CMCR members. PMID:21961967

Yoshizumi, Terry; Brady, Samuel L.; Robbins, Mike E.; Bourland, J. Daniel

2013-01-01

367

Direct fitness for dynamic kin selection.  

PubMed

The direct-fitness approach to modelling the evolution of social traits is an alternative to the classical inclusive-fitness-based approach. Despite both its utility and popularity, the direct-fitness approach has not yet been extended to include the analysis of dynamic traits, i.e. traits whose level of expression may vary over time. In this article, I apply the direct-fitness approach to cope with the evolution of a dynamic resource-allocation behaviour when this behaviour influences the fitness of relatives. I am able to implement the direct-fitness approach using components (reproductive value, fitness changes and measures of relatedness) found in standard, social-evolutionary models. I illustrate the modified direct-fitness model with an example studied by previous authors, and I show how the direct-fitness perspective can aid the validation of analytical results by means of a genetic algorithm. PMID:21585585

Wild, G

2011-07-01

368

Multivariate Monte Carlo Model Fitting  

NASA Astrophysics Data System (ADS)

We present a new method for analyzing multi-dimensional data. The method uses an astrophysical and instrument response Monte Carlo to simulate photons and then iteratively analyze the data. The simulated photons are then compared directly with the measured values for the data with a new multivariate generalization of the Cramér-von Mises and Kolmogorov-Smirnov statistic. Techniques for model fitting, error estimation, and deconvolution using this method are discussed. Examples of this approach using Chandra observations of X-ray clusters of galaxies and XMM-Newton Reflection Grating Spectrometer data are presented.

Peterson, J. R.; Jernigan, J. G.; Kahn, S. M.

2000-05-01

369

Whole-body biodistribution and radiation dosimetry in monkeys and humans of the phosphodiesterase 4 radioligand [11  

E-print Network

Whole-body biodistribution and radiation dosimetry in monkeys and humans of the phosphodiesterase 4. Keywords: [11 C](R)-Rolipram; Positron emission tomography; Dosimetry; Biodistribution 1. Introduction

Shen, Jun

370

The iFit: an integrated physical fitness testing system to evaluate the degree of physical fitness of the elderly.  

PubMed

This paper presents an integrated physical fitness testing system (iFit) that evaluates the physical fitness of older adults. The intent of the test is to help them manage and promote their health and mitigate the effects of aging. National protocols of physical fitness were implemented to support the assessment. The proposed system encompasses four modules of physical fitness assessment for both users and medical professionals. The test information will be recorded and managed through a wireless sensor network that will enable a better understanding of users' fitness states. Furthermore, the iFit has been validated by a test session attended by elderly participants. The results show that there is a significant correlation between iFit use in the test of flexibility, grip strength, and balance, compared to conventional methods. PMID:22899570

Tseng, Kevin C; Wong, Alice May-Kuen; Hsu, Chien-Lung; Tsai, Tsai-Hsuan; Han, Chang-Mu; Lee, Ming-Ren

2013-01-01

371

Developing a Procedure for the Characterization of Mechanical Properties of Collagen Gels  

NASA Astrophysics Data System (ADS)

The characterization of bulk mechanical properties of type I collagen gels is critical to understanding the role of collagen in the extracellular matrix (ECM), and developing biocompatible devices for use in the human body. Understanding the mechanical properties of the gel state of collagen can lead to the ability to adjust these properties for multiple uses. Here, we examined the Young's modulus of the synthesized gels. This project used a microrheological approach to discover these properties. Gels were first formed using a known process and magnetic microspheres were embedded in the gel prior to formation. An optical microscope was fitted with a magnetic chamber used to drive the embedded beads in two modes, an oscillatory motion and a pulse motion. Tracking software was modified and used to analyze the motion of the beads recorded with a CCD camera on the microscope. These techniques should be sufficient to obtain a reliable value for the Young's modulus of collagen gels, as well as other similar materials.

Chambers, Christopher; Lovelady, Heather; Matthews, Garrett

2011-03-01

372

Whole Protein Native Fitness Potentials  

NASA Astrophysics Data System (ADS)

Protein structure prediction can be separated into two tasks: sample the configuration space of the protein chain, and assign a fitness between these hypothetical models and the native structure of the protein. One of the more promising developments in this area is that of knowledge based energy functions. However, standard approaches using pair-wise interactions have shown shortcomings demonstrated by the superiority of multi-body-potentials. These shortcomings are due to residue pair-wise interaction being dependent on other residues along the chain. We developed a method that uses whole protein information filtered through machine learners to score protein models based on their likeness to native structures. For all models we calculated parameters associated with the distance to the solvent and with distances between residues. These parameters, in addition to energy estimates obtained by using a four-body-potential, DFIRE, and RWPlus were used as training for machine learners to predict the fitness of the models. Testing on CASP 9 targets showed that our method is superior to DFIRE, RWPlus, and the four-body potential, which are considered standards in the field.

Faraggi, Eshel; Kloczkowski, Andrzej

2013-03-01

373

Social personality trait and fitness  

PubMed Central

Several recent studies have explored various aspects of animal personality and their ecological consequences. However, the processes responsible for the maintenance of personality variability within a population are still largely unknown. We have recently demonstrated that social personality traits exist in the common lizard (Lacerta vivipara) and that the variation in sociability provides an explanation for variable dispersal responses within a given species. However, we need to know the fitness consequences of variation in sociability across environmental contexts in order to better understand the maintenance of such variation. In order to achieve this, we investigated the relationship between sociability and survival, body growth and fecundity, in one-year-old individuals in semi-natural populations with varying density. ‘Asocial’ and ‘social’ lizards displayed different fitness outcomes in populations of different densities. Asocial lizards survived better in low-density populations, while social females reproduced better. Spatiotemporal variation in environmental conditions might thus be the process underlying the maintenance of these personality traits within a population. Finally, we also discuss the position of sociability in a more general individual behavioural pattern including boldness, exploration and aggressiveness. PMID:18755678

Cote, J; Dreiss, A; Clobert, J

2008-01-01

374

Generative force of self-oscillating gel.  

PubMed

We succeeded in measuring the generative force of a self-oscillating polymer gel in an aqueous solution comprising the three substrates of the Belousov-Zhabotinsky (BZ) reaction (malonic acid, sodium bromate, and nitric acid) under constant temperature. In this study, we developed an apparatus with a microforce sensor for measuring the generative force of small-sized gels (1 mm(3)). The self-oscillating polymer gel directly converts the chemical energy of the BZ reaction into mechanical work. It was determined that the generative force of the self-oscillating gel was 972 Pa, and the period of self-oscillation was 480 s at 18 °C. We demonstrated that the generative force of the gel was about a hundredth the generative force of a muscle in the body. We analyzed the time dependence of the color change in the self-oscillating polymer gel. The color of the gel changed periodically owing to the cyclic change in the redox state of the Ru moiety, induced by the BZ reaction. The peaks of the waveforms of the generative force and color change were almost identical. This result showed that the generative force was synchronized with the periodical change in the oxidation number of the Ru catalytic moiety in the gel. To understand a theoretical basis for the generative force of a self-oscillating gel, we considered a general theory that is based on the volume phase transition of gel and the two-parameter Oregonator model of the BZ reaction. PMID:24524539

Hara, Yusuke; Mayama, Hiroyuki; Morishima, Keisuke

2014-03-01

375

Photorefractive sol-gel materials  

SciTech Connect

The authors report the synthesis and characterization of photorefractive sol-gel materials that possess covalently attached push-pull azobenzene and carbazole moieties. Molecular structural characterization of the modified silane monomers was achieved by {sup 1}H NMR and infra red spectroscopy. The second-order nonlinear optical properties of the organic-inorganic hybrid films prepared from modified silane monomers were evaluated by second-harmonic generation. The stabilized value of the second harmonic coefficient, d{sub 33}, of films poled by corona discharge, at 1,064 nm fundamental wavelength was found to be 107 pm/V. Photorefractivity was clearly displayed from a two beam coupling experiment.

Chaput, F.; Boilot, J.P.; Gacoin, T. [Ecole Polytechnique, Palaiseau (France); Darracq, B.; Riehl, D.; Canva, M.; Levy, Y.; Brun, A. [CNRS, Orsay (France)

1996-12-31

376

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

NASA Astrophysics Data System (ADS)

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

Sharpe, Peter

2009-04-01

377

33 CFR 159.87 - Removal fittings.  

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.87 Removal fittings. If sewage removal fittings or adapters are provided with the...

2014-07-01

378

33 CFR 159.87 - Removal fittings.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.87 Removal fittings. If sewage removal fittings or adapters are provided with the...

2010-07-01

379

33 CFR 159.87 - Removal fittings.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.87 Removal fittings. If sewage removal fittings or adapters are provided with the...

2011-07-01

380

33 CFR 159.87 - Removal fittings.  

Code of Federal Regulations, 2013 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.87 Removal fittings. If sewage removal fittings or adapters are provided with the...

2013-07-01

381

33 CFR 159.87 - Removal fittings.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.87 Removal fittings. If sewage removal fittings or adapters are provided with the...

2012-07-01

382

14 CFR 31.43 - Fitting factor.  

Code of Federal Regulations, 2012 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Design Construction § 31.43 Fitting factor...fitting factor need not be used if the joint design is made in accordance with approved...

2012-01-01

383

Association Between Physical Fitness and Dementia  

MedlinePLUS

The Association Between Physical Fitness and Dementia The full report is titled “The Association Between Midlife Cardiorespiratory Fitness Levels and Later-Life Dementia. A Cohort Study.” It is in ...

384

14 CFR 31.43 - Fitting factor.  

Code of Federal Regulations, 2011 CFR

...and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Design Construction § 31.43 Fitting factor. (a) A fitting factor of at least 1.15 must be used in...

2011-01-01

385

14 CFR 31.43 - Fitting factor.  

Code of Federal Regulations, 2010 CFR

...and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Design Construction § 31.43 Fitting factor. (a) A fitting factor of at least 1.15 must be used in...

2010-01-01

386

An Evaluation of Fitness Reports Scales.  

National Technical Information Service (NTIS)

A sample of convenience was obtained in which 15 officers anonymously completed fitness reports on each other. Fitness report scales were examined to determine their quality based on the statistical considerations of a 'discrimination' and 'disagreement' ...

W. H. Githens, L. A. Lacey

1970-01-01

387

A Novel Way to Promote Youth Fitness.  

ERIC Educational Resources Information Center

Basic steps in organizing and implementing Fun and Fitness Day are outlined. This event, jointly planned by local schools and Triton College, provided 1800 elementary students with health-related fitness testing and a day of fun and competition. (IAH)

Crum, Tom

1989-01-01

388

Twenty new ISO standards on dosimetry for radiation processing  

NASA Astrophysics Data System (ADS)

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

Farrar, H., IV

2000-03-01

389

Evaluation of the breast absorbed dose distribution using the Fricke Xylenol Gel  

NASA Astrophysics Data System (ADS)

During a breast cancer radiotherapy treatment, several issues have to be taken into account, among them, hot spots, gradient of doses delivered over the breast, as well as in the lungs and the heart. The present work aims to apply the Fricke Xylenol Gel (FXG) dosimeter in the study of these issues, using a CCD camera to analyse the dose deposited distribution. Thus, the CCD was used to capture the images of different cuvettes that were filled with FXG and irradiated considering analogous setups employed in breast cancer radiotherapy treatments. Thereafter, these pictures where processed in a MatLab routine and the spatial dose distributions could be evaluated. These distributions were compared with the ones that were obtained from dedicated treatment planning's softwares. According to the results obtained, the FXG, allied with the CCD system, has shown to be a complementary tool in dosimetry, helping to prevent possible complications during breast cancer treatments.

Czelusniak, C.; Del Lama, L. S.; Moreira, M. V.; De Almeida, A.

2010-11-01

390

Physical characteristics related to bra fit  

Microsoft Academic Search

Producing well-fitting garments has been a challenge for retailers and manufacturers since mass production began. Poorly fitted bras can cause discomfort or pain and result in lost sales for retailers. Because body contours are important factors affecting bra fit, this study analyses the relationship of physical characteristics to bra-fit problems. This study has used 3-D body-scanning technology to extract upper

Chin-Man Chen; Karen LaBat; Elizabeth Bye

2010-01-01

391

Package `FitARMA' July 5, 2007  

E-print Network

Package `FitARMA' July 5, 2007 Title ARMA fitting Version 1.0 Date 2007-01-05 Author A.I. McLeod Maintainer A.I. McLeod Depends R (>= 2.0.0), FitAR Description Implements fast maximum(p,d,q) model using the algorithm given in McLeod and Zhang (2007). Usage FitARMA(z, order = c(0, 0, 0), demean

McLeod, Ian

392

Automated apparatus for producing gradient gels  

DOEpatents

Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

Anderson, N.L.

1983-11-10

393

Automated apparatus for producing gradient gels  

DOEpatents

Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

Anderson, Norman L. (Clarendon Hills, IL)

1986-01-01

394

[Glaucoma and aircraft pilot fitness].  

PubMed

Two completely different questions arise when considering glaucoma and fitness to fly: Firstly, what is the risk for a passenger with glaucoma? Secondly, what is the flight safety risk connected with pilots suffering from glaucoma? National requirements and international standards pay little regard to this disease. This is astonishing, given that the perception of flight information in the peripheral visual field is of great importance in the cockpit. On one hand, diagnostic glaucoma examinations for pilots are mainly insufficient, and on the other, progressive visual field deficiencies may go undetected because of long intervals between examinations. Intraocular pressure may increase while flying in aircraft, e.g. in the case of negative g-load. Frequent flights at high altitudes without pressurized cabin air and with decreased oxygen supply, and therefore decreased tissue oxygen saturation, may represent a risk, especially for patients with progressive nerve fibre loss. PMID:8867166

Schwartz, R; Stern, C; Klemm, M; Draeger, J; Winter, R

1996-02-01

395

Continuum Fitting HST QSO Spectra  

NASA Technical Reports Server (NTRS)

The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.

Tytler, David; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

396

Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography  

NASA Astrophysics Data System (ADS)

The purpose of this study was to compare characteristics of radiochromic gel - Turnbull Blue gel (TB gel) with polymer gel - polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0-15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV-vis Spectrophotometer Helios ? and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. Gel dosimeters are suitable for steep dose gradient verification. An optical tomography evaluation method is successful. Dose response characteristics of TB gel and PAGAT gel are presented.

Pila?ová (Vávr?), Kate?ina; Kozubíková, Petra; Šolc, Jaroslav; Sp?vá?ek, Václav

2014-11-01

397

A probabilistic gastrointestinal tract dosimetry model  

NASA Astrophysics Data System (ADS)

In internal dosimetry, the tissues of the gastrointestinal (GI) tract represent one of the most radiosensitive organs of the body with the hematopoietic bone marrow. Endoscopic ultrasound is a unique tool to acquire in-vivo data on GI tract wall thicknesses of sufficient resolution needed in radiation dosimetry studies. Through their different echo texture and intensity, five layers of differing echo patterns for superficial mucosa, deep mucosa, submucosa, muscularis propria and serosa exist within the walls of organs composing the alimentary tract. Thicknesses for stomach mucosa ranged from 620 +/- 150 mum to 1320 +/- 80 mum (total stomach wall thicknesses from 2.56 +/- 0.12 to 4.12 +/- 0.11 mm). Measurements made for the rectal images revealed rectal mucosal thicknesses from 150 +/- 90 mum to 670 +/- 110 mum (total rectal wall thicknesses from 2.01 +/- 0.06 to 3.35 +/- 0.46 mm). The mucosa thus accounted for 28 +/- 3% and 16 +/- 6% of the total thickness of the stomach and rectal wall, respectively. Radiation transport simulations were then performed using the Monte Carlo N-particle transport code (MCNP) 4C transport code to calculate S values (Gy/Bq-s) for penetrating and nonpenetrating radiations such as photons, beta particles, conversion electrons and auger electrons of selected nuclides, I123, I131, Tc 99m and Y90 under two source conditions: content and mucosa sources, respectively. The results of this study demonstrate generally good agreement with published data for the stomach mucosa wall. The rectal mucosa data are consistently higher than published data compared with the large intestine due to different radiosensitive cell thicknesses (350 mum vs. a range spanning from 149 mum to 729 mum) and different geometry when a rectal content source is considered. Generally, the ICRP models have been designed to predict the amount of radiation dose in the human body from a "typical" or "reference" individual in a given population. The study has been performed to develop a more complete set of dosimetry information on the gastrointestinal tract (GI) for internal dose assessment by implementing uncertainty parameters such as gender, age, meal phase, smoking effect, menses and pregnancy, etc. In the calculation of Us for the CDE in ICRP Publication 30, single deterministic values for the ICRP 30 gastro intestinal tract compartment model are given without any consideration of parameter uncertainties or individual variability. The present study showed that all uncertainty parameters used in the ICRP 30 GI tract model have a specific probability density function. The results show Us represent much higher value in the stomach due to increased resident time depending on its uncertainty, while Us approaches to the standard value in upper large and lower large intestines.

Huh, Chulhaeng

398

Cooling rate effects in thermoluminescence dosimetry grade lithium flouride. Implications for practical dosimetry.  

PubMed

A systematic investigation of the effects of cooling rates in the range of 10(-1) to 2 X 10(5) degrees C min-1 applied to TLD-700, LiF thermoluminescence dosemeters has shown that the 'transfer sensitivity' effect observed by Booth, Johnson and Attix (1972) is only of importance for cooling rates greater than 10(3) degrees C min-1. Although it is concluded that for practical dosimetry purposes the effect may be ignored it is not clear why Booth et al. observed such large changes and until this discrepancy is explained it is recommended that a low temperature pre-irradiation anneal should be used. PMID:1267932

Mason, E W; McKinlay, A F; Clark, I

1976-01-01

399

Fractal fits to Riemann zeros  

E-print Network

Wu and Sprung (Phys. Rev. E 48, 2595 (1993)) reproduced the first 500 nontrivial Riemann zeros, using a one-dimensional local potential model. They concluded -- and similarly van Zyl and Hutchinson (Phys. Rev. E 67, 066211 (2003)) -- that the potential possesses a fractal structure of dimension d=3/2. We model the nonsmooth fluctuating part of the potential by the alternating-sign sine series fractal of Berry and Lewis A(x,g). Setting d=3/2, we estimate the frequency parameter (gamma), plus an overall scaling parameter (sigma) we introduce. We search for that pair of parameters (gamma,sigma) which minimizes the least-squares fit S_{n}(gamma,sigma) of the lowest n eigenvalues -- obtained by solving the one-dimensional stationary (non-fractal) Schrodinger equation with the trial potential (smooth plus nonsmooth parts) -- to the lowest n Riemann zeros for n =25. For the additional cases we study, n=50 and 75, we simply set sigma=1. The fits obtained are compared to those gotten by using just the smooth part of the Wu-Sprung potential without any fractal supplementation. Some limited improvement -- 5.7261 vs. 6.39207 (n=25), 11.2672 vs. 11.7002 (n=50) and 16.3119 vs. 16.6809 (n=75) -- is found in our (non-optimized, computationally-bound) search procedures. The improvements are relatively strong in the vicinities of gamma=3 and (its square) 9. Further, we extend the Wu-Sprung semiclassical framework to include higher-order corrections from the Riemann-von Mangoldt formula (beyond the leading, dominant term) into the smooth potential.

Paul B. Slater

2006-06-01

400

Modeling of fibrin gels based on confocal microscopy and light-scattering data.  

PubMed

Fibrin gels are biological networks that play a fundamental role in blood coagulation and other patho/physiological processes, such as thrombosis and cancer. Electron and confocal microscopies show a collection of fibers that are relatively monodisperse in diameter, not uniformly distributed, and connected at nodal points with a branching order of ?3-4. Although in the confocal images the hydrated fibers appear to be quite straight (mass fractal dimension D(m) = 1), for the overall system 1gels made of cylindrical sticks of diameter d, density ?, and average length , joined at randomly distributed nodal points. The resulting 3D network strikingly resembles real fibrin gels and can be sketched as an assembly of densely packed fractal blobs, i.e., regions of size ?, where the fiber concentration is higher than average. The blobs are placed at a distance ?0 between their centers of mass so that they are overlapped by a factor ? =?/?0 and have D(m) ?1.2-1.6. The in silico gels' structure is quantitatively analyzed by its 3D spatial correlation function g(3D)(r) and corresponding power spectrum I(q) = FFT(3D[g3D(r)]), from which ?, d, D(m), ?, and ?0 can be extracted. In particular, ?0 provides an excellent estimate of the gel mesh size. The in silico gels' I(q) compares quite well with real gels' elastic light-scattering measurements. We then derived an analytical form factor for accurately fitting the scattering data, which allowed us to directly recover the gels' structural parameters. PMID:23473498

Magatti, Davide; Molteni, Matteo; Cardinali, Barbara; Rocco, Mattia; Ferri, Fabio

2013-03-01

401

Hydra progress: fitting beginnings Hydra bunch  

E-print Network

and opacity PVM (Noble, etc.) PVM getting used... #12;Most recent progress: fitting Define parameters DefineHydra progress: fitting beginnings Hydra bunch: Mike, Mike, Mike John, John, Dan September 2005 #12;Motivation: 3D Sources #12;Cont. ... #12;OK ..., the real Motivation... Fit_fun = "( wabs(1) * vnei(1) )"; VS

Dewey, Daniel

402

The Army's High Priority Physical Fitness Program.  

ERIC Educational Resources Information Center

This article explores the importance of physical fitness in the United States Army. The development of expanded fitness assessment and programs is related to health and the prevention of coronary heart disease. Improved physical training programs, improved nutrition, and fundamental research are necessary for maintaining a highly fit and healthy…

Drews, Fred R.

1984-01-01

403

Trends in Physical Fitness: A Personal Perspective.  

ERIC Educational Resources Information Center

In the early days of physical education, the value of physical fitness was associated with preparation for defense in wartime and preventive medicine. Physical fitness waned in importance in the period between the two World Wars, to become concommitant to other objectives of physical education. A resurgence in emphasis on fitness was triggered and…

Clarke, H. Harrison

404

Physical Fitness in the Elementary School.  

ERIC Educational Resources Information Center

The author, Executive Director of the Presidents Council on Physical Fitness and Sports, presents a seven-question test for parents on the physical education program of their elementary school children, and examines health and physical fitness concerns of children and adults. Emphasis is placed on the early development of physical fitness as a…

Conrad, C. Carson

405

Fitness: A Family Affair. Spotlight: Physical Development.  

ERIC Educational Resources Information Center

Discusses ways parents can help children create a lifestyle that supports physical fitness, focusing on motivation for children and parents. Defines the components of fitness: cardiorespiratory endurance, muscular strength, muscular endurance, and flexibility. Presents information on developing adult and child fitness programs, including a workout…

Turner, Joy

2000-01-01

406

Fall Semester 2013 Group Fitness Classes  

E-print Network

IN DURATION UNLESS NOTED *Yoga mats recommended for all Yoga and Pilates classes **Water bottles and sweat. Pilates* Linda B. 6:15 am/ Group Fit 2 Spinning** Melis Spinning ** Melis 6:15 am/ Group Fit 3 Restorative Pilates* Julia Pilates* Julia 11:10 am/ Group Fit 3 Int/Adv Yoga* Courtney Int/Adv Yoga* Courtney 11:30 am

Maxwell, Bruce D.

407

Blue emission in tetraethoxysilane and silica gels  

Microsoft Academic Search

Tetraethoxysilane (TEOS), a well-known SiO2 precursor, and silica gels prepared with it were characterized in terms of their optical properties in the 200–800 nm range. A distinctive blue emission is detected not only in the gels but also in the TEOS itself. Further heat treatments of the gels allowed the evolution of the blue signal to be followed; the origin

J. M. García; M. A. Mondragón; C. S. Téllez; A. Campero; V. M. Castaño

1995-01-01

408

Gel time of calcium acrylate grouting material.  

PubMed

Calcium acrylate is a polymerized grout, and can polymerize in an aqueous solution. The polymerization reaction utilizes ammonium persulfate as a catalyst and sodium thiosulfate as the activator. Based on the theory of reaction kinetics, this study on the relation between gel time and concentration of activator and catalyst showed that gel time of calcium acrylate is inversely proportional to activator and catalyst concentration. A formula of gel time is proposed, and an example is provided to verify the proposed formula. PMID:15236477

Han, Tong-Chun

2004-08-01

409

Optoacoustic online dosimetry during selective RPE treatment  

NASA Astrophysics Data System (ADS)

Introduction: The selective RPE treatment (SRT) is a new method, which targets retinal diseases associated with disorders in the retinal pigment epithelium (RPE). By applying a train of ?s laser pulses, it is possible to selectively damage RPE cells while sparing the adjacent photoreceptors and the neural retina. Due to the ophthalmoscopic invisibility of the RPE effects we investigated an optoacoustic (OA) on-line dosimetry system to monitor RPE damage non-invasively. Material and Methods: For in vitro experiments porcine RPE was irradiated with a Nd:YLF laser pulse train (527nm, 1.7?s, 5-40?J, 30 pulses, 100 Hz). Pressure waves (optoacoustic transients) generated at the RPE were measured with a piezoelectric transducer. The RPE cell damage was visualised by fluorescence microscopy by means of the vitality stain CalceinAM. During 27 patient treatments (527nm, 1.7?s, 50-150?J, 30 pulses, 100 Hz) the optoacoustic signals were measured with an ultrasonic transducer embedded in the contact lens. The RPE leakage was visualized by fluorescein and ICG angiography. Results: In vitro: Below the RPE cell damage threshold, the optoacoustic transients from each single pulse are almost similar. With RPE damage, fluctuations of the individual transients are observed during the pulse train. These fluctuations can be explained by statistical irregular microbubble formation around the strong light absorbing melanosomes inside the RPE cells, which occur after the temperature exceeds the vaporization threshold. The transient microbubbles probably lead to RPE cell disruption. An optoacoustic value (OA-value) calculated from the fluctuations was defined in order to assess RPE damage. Patient treatment: If optoacoustic pulse-to-pulse fluctuations were measured, RPE leakage was observed in fluorescein and ICG angiography. In 96% of the irradiated areas, RPE-leakage in fluorescein angiography and OA-value correlated. The stronger the optoacoustic pulse-to-pulse fluctuations, thus the higher the OA-value, the more intense angiographic leakage was observed in ICG-angiography. Conclusion: A non-invasive optoacoustic on-line dosimetry control to monitor RPE damage during SRT was developed. In order to avoid invasive angiography, it is currently evaluated in a multicenter clinical SRT study.

Schuele, Georg; Elsner, Hanno; Hoerauf, Hans; Framme, Carsten; Roider, Johann; Birngruber, Reginald; Brinkmann, Ralf

2004-07-01

410

21 CFR 866.4900 - Support gel.  

Code of Federal Regulations, 2010 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel. (a)...

2010-04-01

411

21 CFR 866.4900 - Support gel.  

Code of Federal Regulations, 2013 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4900 Support gel. (a)...

2013-04-01

412

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

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

Rathbone, Bruce A.

2011-04-04

413

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

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

Rathbone, Bruce A.

2010-04-01

414

Hanford External Dosimetry Technical Basis Manual PNL-MA-842  

SciTech Connect

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

Rathbone, Bruce A.

2007-03-12

415

The Swiss IMRT dosimetry intercomparison using a thorax phantom H. Schiefer1  

E-print Network

The Swiss IMRT dosimetry intercomparison using a thorax phantom H. Schiefer1 , A. Fogliata2 , G: +41 71 494 2893 Email: johann.schiefer@kssg.ch #12;The Swiss IMRT dosimetry intercomparison using) dosimetry intercomparison was carried out for all 23 radiation oncology institutions in Switzerland

Krusche, Bernd

416

Elsevier Science 1 Use of the GATE Monte Carlo package for dosimetry  

E-print Network

Elsevier Science 1 Use of the GATE Monte Carlo package for dosimetry applications D. Visvikis, a* M Angeles, USA Abstract One of the roles for MC simulation studies is in the area of dosimetry. A number of different codes dedicated to dosimetry applications are available and widely used today, such as MCNP

Paris-Sud XI, Université de

417

Advancements in accuracy of the alanine dosimetry system. Part 1. The eects of environmental humidity  

E-print Network

Advancements in accuracy of the alanine dosimetry system. Part 1. The eects of environmental of alanine dosimetry by changing the resonant cavity Q-factor. This is particularly important when irradiated is demonstrated. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Alanine; EPR dosimetry; Humidity

418

Dosimetry Procedure: 7.82 Created: 10/08/2013 Version: 1.0 Revised  

E-print Network

Dosimetry Procedure: 7.82 Created: 10/08/2013 Version: 1.0 Revised: Environmental Health & Safety schedule can be found online at http://www.ehs.columbia.edu/SafetyTrainingSchedules.html #12;Dosimetry contact 1. Dosimetry Coordinator: 212-305-5359 2. Radiation Safety: 212-305-0303 F. Medical Surveillance 1

Jia, Songtao

419

NOVEL Al2O3:C,Mg FLUORESCENT NUCLEAR TRACK DETECTORS FOR PASSIVE NEUTRON DOSIMETRY  

E-print Network

NOVEL Al2O3:C,Mg FLUORESCENT NUCLEAR TRACK DETECTORS FOR PASSIVE NEUTRON DOSIMETRY G. Jeff Sykora1 in the development of a fluorescent nuclear track detector (FNTD) for neutron and heavy charged particle dosimetry for neutron dosimetry because they have 100% n/g dis- crimination. For instance, CR-39 plastic nuclear track

420

SPIE Proceedings, Ophthalmic Technologies XVI, vol. 6138 (2006) Noninvasive Dosimetry and Monitoring of TTT  

E-print Network

SPIE Proceedings, Ophthalmic Technologies XVI, vol. 6138 (2006) 1 Noninvasive Dosimetry and the lack of immediately observable outcome of the therapy, a real-time dosimetry is highly desirable. We-time monitoring and dosimetry of TTT. A 795nm laser was applied in rabbit eyes for 60 seconds using a 0.86mm

Palanker, Daniel

421

Radiochromic film for medical radiation dosimetry Martin J. Butsona,b  

E-print Network

Radiochromic film for medical radiation dosimetry Martin J. Butsona,b , Peter K.N. Yua,* , Tsang extensively for medical purposes in diagnostic and therapeutic procedures. Dosimetry of these radiation) dosimetry more accurately and inexpensively. Radiochromic film dosimeters are now available in formats

Yu, K.N.

422

TESLA-FEL 2007-02 Radiation dosimetry in FLASH Tunnel using  

E-print Network

1 TESLA-FEL 2007-02 Radiation dosimetry in FLASH Tunnel using Passive dosimeters Bhaskar Mukherjee, Radiation dosimetry, Radiation effect, Superconducting Cavities, XFEL 1. INTRODUCTION In April 2006, at DESY) along the linac. #12;2 To circumvent the above shortcomings we have developed novel passive dosimetry

423

NIAID/NCI/NIST Workshop on Radiation Dosimetry Standardization for Radiobiology  

E-print Network

1 NIAID/NCI/NIST Workshop on Radiation Dosimetry Standardization for Radiobiology September 15 ­ 16, 2011, NIST Why is Dosimetry and Standardization Important in Radiobiology? ­ The Physics Framework and Precision? ·Typical uncertainties associated with dosimetry. ·Impact of today's increased resolution

424

A stochastic collocation method combined with a reduced basis method to compute uncertainties in numerical dosimetry  

E-print Network

uncertainties in numerical dosimetry M. A. Drissaoui1,2 , S. Lanteri3 , P. Lévêque4 , F. Musy2 , L. Nicolas1 , R with a stochastic problem in a numerical dosimetry application in which the field solutions are computed using--Finite-element methods, numerical analysis, dosimetry. I. INTRODUCTION he lack of knowledge on the electric parameters

Paris-Sud XI, Université de

425

Advancements in accuracy of the alanine EPR dosimetry Part III: Usefulness of an adjacent reference sample  

E-print Network

Advancements in accuracy of the alanine EPR dosimetry system Part III: Usefulness of an adjacent methodological aspects of using such adjacent reference samples in alanine dosimetry and provides illustrations of the usefulness of this technique. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Alenine dosimetry

426

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

E-print Network

Note MODIFICATION OF SHIRT BUTTONS FOR RETROSPECTIVE RADIATION DOSIMETRY AFTER A RADIOLOGICAL EVENT. Health Phys. 100(5):542­547; 2011 Key words: detector, thermoluminescent; dosimetry, person- nel to calculate doses on an individual basis, exposures might have to be assessed by biological dosimetry in order

Brenner, David Jonathan

427

ORNL/TM-2008/046 Analysis of HFIR Dosimetry Experiments  

E-print Network

ORNL/TM-2008/046 Analysis of HFIR Dosimetry Experiments Performed in Cycles 400 and 401 September and Technology Division ANALYSIS OF HFIR DOSIMETRY EXPERIMENTS PERFORMED IN CYCLES 400 AND 401 I. Remec and C. A..................................................................................................................................1 2. DOSIMETRY EXPERIMENT

Pennycook, Steve

428

Absorbed-dose/dose-rate dependence studies for the alanine-EPR dosimetry system  

E-print Network

Absorbed-dose/dose-rate dependence studies for the alanine-EPR dosimetry system M.F. Desrosiers and Technology, Gaithersburg, Maryland, USA a r t i c l e i n f o Keywords: Alanine Dosimeter Dosimetry Electron t Over the course of the last decade, routine monitoring of the alanine dosimetry system revealed a small

429

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

E-print Network

1 Radiation Protection Dosimetry Vol. 97, No. 3, pp. 279-285 (2001) Nuclear Technology Publishing of radioactive airborne particles, internal radiation dosimetry, and the dose-response relationships for internally deposited radionuclides. He is editor of the textbook, Internal Radiation Dosimetry, published

Brenner, David Jonathan

430

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

E-print Network

Polyvinyltoluene scintillators for relative ion dosimetry: an investigation with Helium, Carbon beam dosimetry, tested with Helium, Carbon and Neon ions having an equivalent range in water of 150 mm and the relative dose. Keywords: Scintillation detectors, dosimetry, ion radiation effects, ion

Boyer, Edmond

431

Numerical dosimetry of currents induced in the human body by ELF magnetic fields  

E-print Network

Numerical dosimetry of currents induced in the human body by ELF magnetic fields Riccardo Scorretti, 2010 Abstract Purpose: The classical - a formulations for numerical dosimetry of currents induced dosimetry, formulation, finite element 1 Introduction The fields induced in the human body by ELF

Paris-Sud XI, Université de

432

Human Biodistribution and Radiation Dosimetry of the Tachykinin NK1 Antagonist Radioligand  

E-print Network

Human Biodistribution and Radiation Dosimetry of the Tachykinin NK1 Antagonist Radioligand [18FRadiation Dosimetry Systems, Inc., San Francisco, California 18F-Labeled substance P antagonist and not concentrated in a small number of radiation sensitive organs. Key Words: [18F]SPA-RQ; PET dosimetry

Shen, Jun

433

Macroscopic to Microscopic Scales of Particulate Dosimetry: From Source to Fate in the Body  

EPA Science Inventory

Additional perspective with regards to particle dosimetry is achieved by exploring dosimetry across a range of scales from macroscopic to microscopic in scope. Typically, one thinks of dosimetry as what happens when a particle is inhaled, where it is deposited, and how it is clea...

434

DNA electrophoresis in agarose gels: A new mobility vs. DNA length dependence  

NASA Astrophysics Data System (ADS)

Separations were performed on double stranded DNA (dsDNA) using electrophoresis. Electrophoresis is the steady transport of particles under the influence of an external electric field. Double stranded DNA fragments ranging in length from 200 base pairs (bp) to 194,000 bp (0.34 nm = 1 bp) were electrophoresed at agarose gel concentrations T = 0.4%--1.5%. The electric field was varied from 0.62 V/cm to 6.21 V/cm. A wide range of electric fields and gel concentrations were used to study the usefulness of a new interpolation equation, 1mL =1mL-( 1mL-1 ms)e-L/g , where mL,ms , and g are independent free fitting parameters. The long length mobility limit is interpreted as mL , the short length mobility limit is ms , and g is the crossover between the long length limit and the short length limit. This exponential relation fit very well (chi2 ? 0.999) when there are two smooth transitions observed in the "reptation plots" (plotting 3mL/m? vs. L) (J. Rousseau, G. Drouin, and G. W. Slater, Phys Rev Lett. 1997, 79, 1945--1948). Fits deviate from the data when three different slopes were observed in the reptation plots. Reptation plots were used to determine a phase diagram for dsDNA migration regimes. The phase diagrams define different regions where mechanisms for molecular transport affect the migration of dsDNA in agarose gels during electrophoresis. The parameters from the equation have also been interpreted to provide a physical description of the structure of the agarose gel by calculating the pore sizes. The relations between the values for the pore sizes and the phase diagrams are interpreted to better understand the migration of the DNA through agarose gels.

Beheshti, Afshin

2002-04-01

435

Free volume effects on the fluorescence characteristics of sol-gel glasses doped with quinine sulphate  

NASA Astrophysics Data System (ADS)

The broadening of the absorption and fluorescence spectra and the red shift of the fluorescence maximum of quinine sulfate doped sol-gel glasses, before and after PMMA polymer impregnation, are investigated at different concentrations. The fluorescence decay of the quinine sulfate doped samples does not fit to a single exponential, as it does in ethanol solutions. We found that a double exponential gives a good fit to the obtained results. Introduction of solvent to fill the pores of the matrix does not only have the same effect as the polymer, but also reveals the strong attachment of the molecules to the pore walls and the influence of the interaction with the cage.

Meneses-Nava, M. A.; Barbosa-García, O.; Díaz-Torres, L. A.; Chávez-Cerda, S.; King, T. A.

1999-12-01

436

Student Perceptions of an Online Medical Dosimetry Program  

SciTech Connect

The University of Wisconsin-La Crosse offers the first online medical dosimetry program in the nation. There is no data to research a program of this type. This research consisted of the evaluation of other distance education programs including health profession programs in addition to face-to-face medical dosimetry programs. There was a need to collect and analyze student perceptions of online learning in medical dosimetry. This research provided a guide for future implementation by other programs as well as validated the University of Wisconsin-La Crosse program. Methodology used consisted of an electronic survey sent to all previous and currently enrolled students in the University of Wisconsin-La Crosse medical dosimetry program. The survey was both quantitative and qualitative in demonstrating attitudinal perceptions of students in the program. Quantitative data was collected and analyzed using a 5-point Likert scale. Qualitative data was gathered based on the open-ended responses and the identifying themes from the responses. The results demonstrated an overall satisfaction with this program, the instructor, and the online courses. Students felt a sense of belonging to the courses and the program. Considering that a majority of the students had never taken an online course previously, the students felt there were no technology issues. Future research should include an evaluation of board exam statistics for students enrolled in the online and face-to-face medical dosimetry programs.

Lenards, Nishele, E-mail: lenards.nish@uwlax.ed [Department of Health Professions/College of Science and Health, Medical Dosimetry Program, University of Wisconsin-La Crosse, La Crosse, WI (United States)

2011-07-01

437

Follow the Family Food and Fitness Formula.  

E-print Network

A total fitness program combines acting fit and eating fit. Either of these factors alone is not enough. For example, some people diet but never exercise. Others exercise vigorously, but ignore good eating habits. And some try to diet... and exercise but can not seem to keep it up for very long. What follows is an easy, practical guide for families who want to eat fit and act fit. Planning Is the Key Random eating can lead to overeating. And meal skipping can be hazardous to your diet...

Cooksey, Dymple; Haggard, Marilyn; Hunt, Alice; Sweeten, Mary; Heussner, Mary Ann

1984-01-01

438

IFSFIT: Spectral Fitting for Integral Field Spectrographs  

NASA Astrophysics Data System (ADS)

IFSFIT is a general-purpose IDL library for fitting the continuum, emission lines, and absorption lines in integral field spectra. It uses PPXF (ascl:1210.002) to find the best fit stellar continuum (using a user-defined library of stellar templates and including additive polynomials), or optionally a user-defined method to find the best fit continuum. It uses MPFIT (ascl:1208.019) to simultaneously fit Gaussians to any number of emission lines and emission line velocity components. It will also fit the NaI D feature using analytic absorption and/or emission-line profiles.

Rupke, David S. N.

2014-09-01

439

Preparation of C[sub 70]-doped solid silica gel via sol-gel process  

Microsoft Academic Search

In this paper, the authors report a successful fabrication of C[sub 70]-doped silica solid gel via the sol-gel technique. The sol-gel process is a technique that can be used to prepare transparent oxide glasses by hydrolysis and condensation of alkoxide precursors. Little or no heating is required, and consequently the gel can be doped with molecules whose poor thermal stability

S. Dai; J. P. Young; R. N. Compton; G. Mamantov

1992-01-01

440

Stacking gels: A method for maximising output for pulsed-field gel electrophoresis.  

PubMed

Pulsed field gel electrophoresis (PFGE), the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility. All the variables that affect pulsed field gels during electrophoresis were taken into consideration. We firstly optimized the parameters to be used and secondly determined whether stacking of five to six gels had any effect on the molecular separation during electrophoresis in comparison with a single gel run. DNA preparation, restriction, electrophoresis, staining and gel documentation was carried out based on previously published methods. Gels were analysed using BioNumerics and dice coefficient and unweighted pair group methods were used to generate dendrograms based on 1.5% tolerance values. Identical band profiles and band resolution-separation were seen in the PFGE patterns with single gel and multiple stacking gels. Cluster analysis further strengthened the fact that results from stacking gels were reproducible and comparable with a single gel run. This method of stacking gels saves time and maximizes the output at the same time. The run time for a single gel was about 28 hours, but with six stacked gels the run time was 54 hours compared with 28 x 6 = 168 hours if they were run separately as single gels thus saving time of 67.86%. Beside the big factor of saving time, stacking gels save resources (electricity, reagents, water, chemicals and working time) by increasing the sample throughput in a shorter time without compromising on quality of data. But optimization of working parameters is vital depending on the PFGE system used. PMID:19384038

Heng, See Kah; Heng, Chua Kek; Puthucheary, S D

2009-01-01

441

Production and characterization of spodumene dosimetric pellets prepared by a sol-gel route  

NASA Astrophysics Data System (ADS)

Spodumene is an aluminosilicate that has shown good results for high-dose TL dosimetry for beta or gamma rays. Due to its chemical composition (LiAlSi2O6) it has potential to be used as a neutron dosimeter. The synthetic spodumene is usually produced by solid state reaction and conventional sol-gel, whose shortcomings arise from the need to employ high temperatures and high cost reagents, respectively. Proteic sol-gel method is promising, because it can reduce production costs and the possibility of environmental contamination. This work reports the production of the spodumene by the proteic sol-gel method using edible unflavored gelatin as a precursor. The product is characterized physically and morphologically, and investigated its applicability as a TL dosimeter. Two sets of samples were prepared using different sources of silicon, one with TEOS (Si(OC3H5)4) and one with SILICA (SiO2). The materials produced were characterized by X-ray diffraction, differential thermal analysis and thermogravimetry in order to evaluate the structural properties, as well as possible changes in physical or chemical properties depending on the temperature. The production of spodumene was successful, with generation of the crystals in the ?-phase with tetragonal structure. Sintered pellets produced from these crystals were irradiated with a 90Sr-90Y source and their TL glow curves were evaluated. Although the samples prepared by the proteic sol-gel method with TEOS presented a lower forming temperature, the samples produced with SILICA showed higher sensitivity to radiation.

Lima, H. R. B. R.; Nascimento, D. S.; Bispo, G. F. C.; Teixeira, V. C.; Valério, M. E. G.; Souza, S. O.

2014-11-01

442

Film Dosimetry for Intensity Modulated Radiation Therapy  

NASA Astrophysics Data System (ADS)

Intensity Modulated Radiation Therapy (IMRT) is an oncology treatment technique that employs non-uniform beam intensities to deliver highly conformal radiation to the targets while minimizing doses to normal tissues and critical organs. A key element for a successful clinical implementation of IMRT is establishing a dosimetric verification process that can ensure that delivered doses are consistent with calculated ones for each patient. To this end we are developing a fast quality control procedure, based on film dosimetry techniques, to be applied to the 6 MV Novalis linear accelerator for IMRT of the Instituto Nacional de Neurología y Neurocirugía (INNN) in Mexico City. The procedure includes measurements of individual fluence maps for a limited number of fields and dose distributions in 3D using extended dose-range radiographic film. However, the film response to radiation might depend on depth, energy and field size, and therefore compromise the accuracy of measurements. In this work we present a study of the dependence of Kodak EDR2 film's response on the depth, field size and energy, compared with those of Kodak XV2 film. The first aim is to devise a fast and accurate method to determine the calibration curve of film (optical density vs. doses) commonly called a sensitometric curve. This was accomplished by using three types of irradiation techniques: Step-and-shoot, dynamic and static fields.

Benites-Rengifo, J.; Martínez-Dávalos, A.; Celis, M.; Lárraga, J.

2004-09-01

443

Optical dosimetry for interstitial photodynamic therapy  

SciTech Connect

An approach to photodynamic treatment of tumors is the interstitial implantation of fiber optic light sources. Dosimetry is critical in identifying regions of low light intensity in the tumor which may prevent tumor cure. We describe a numerical technique for calculating light distributions within tumors, from multiple fiber optic sources. The method was tested using four translucent plastic needles, which were placed in a 0.94 X 0.94 cm grid pattern within excised Dunning R3327-AT rat prostate tumors. A cylindrical diffusing fiber tip, illuminated by 630 nm dye laser light was placed within one needle and a miniature light detector was placed within another. The average penetration depth in the tumor region between the two needles was calculated from the optical power measured by the detector, using a modified diffusion theory. Repeating the procedure for each pair of needles revealed significant variations in penetration depth within individual tumors. Average values of penetration depth, absorption coefficient, scattering coefficient, and mean scattering cosine were 0.282 cm, 0.469 cm-1, 250 cm-1 and 0.964, respectively. Calculated light distributions from four cylindrical sources in tumors gave reasonable agreement with direct light measurements using fiber optic probes.

Arnfield, M.R.; Tulip, J.; Chetner, M.; McPhee, M.S. (Cross Cancer Institute, Edmonton, Alberta (Canada))

1989-07-01

444

Inhalation exposure technology, dosimetry, and regulatory issues.  

PubMed

Inhalation toxicology technology has provided the scientific community with important advances in studies of inhaled toxicants. These advances include new and more efficient exposure systems (e.g., flow-past nose-only exposure systems), and improved approaches to inhalation chamber environmental control (e.g., temperature, humidity, air quality). Practical problems and approaches to testing and operating inhalation exposure systems and the advantages and disadvantages of the major inhalation exposure types (e.g., whole-body, nose-only) are discussed. Important aspects of study design, such as high level particulate exposures resulting in large lung burdens (e.g., greater than or equal to 2 mg/g of lung), slowed pulmonary clearance rates, and nonspecific toxicity are considered, along with practical issues of comparative dosimetry. Regulatory guidelines have continued to present challenges in designing and conducting acute, subchronic, and chronic inhalation studies. The important regulatory issue of performing acute inhalation toxicity studies at high aerosol concentrations and "respirable" particle size distribution is discussed. PMID:1813983

Dorato, M A; Wolff, R K

1991-01-01

445

Biological dosimetry by interphase chromosome painting  

NASA Technical Reports Server (NTRS)

Both fluorescence in situ hybridization of metaphase spreads with whole-chromosome probes and premature chromosome condensation in interphase nuclei have been used in the past to estimate the radiation dose to lymphocytes. We combined these techniques to evaluate the feasibility of using painted interphase chromosomes for biodosimetry. Human peripheral lymphocytes were exposed to gamma rays and fused to mitotic Chinese hamster cells either immediately after irradiation or after 8 h incubation at 37 degrees C. Interphase or metaphase human chromosomes were hybridized with a composite probe specific for human chromosomes 3 and 4. The dose-response curve for fragment induction immediately after irradiation was linear; these results reflected breakage frequency in the total genome in terms of DNA content per chromosome. At 8 h after irradiation, the dose-response curve for chromosome interchanges, the prevalent aberration in interphase chromosomes, was linear-quadratic and similar to that observed for metaphase chromosomes. These results suggest that painting prematurely condensed chromosomes can be useful for biological dosimetry when blood samples are available shortly after the exposure, or when interphase cells are to be scored instead of mitotic cells.

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

1996-01-01

446

Biological dosimetry by interphase chromosome painting  

SciTech Connect

Both fluorescence in situ hybridization of metaphase spreads with whole-chromosome probes and premature chromosome condensation in interphase nuclei have been used in the past to estimate the radiation dose to lymphocytes. We combined these techniques to evaluate the feasibility of using painted interphase chromosomes for biodosimetry. Human peripheral lymphocytes were exposed to {gamma} rays and fused to mitotic Chinese hamster cells either immediately after irradiation or after 8 h incubation at 37{degrees}C. Interphase or metaphase human chromosomes were hybridized with a composite probe specific for human chromosomes 3 and 4. The dose-response curve for fragment induction immediately after irradiation was linear; these results reflected breakage frequency in the total genome in terms of DNA content per chromosome. At 8 h after irradiation, the dose-response curve for chromosome interchanges, the prevalent aberration in interphase chromosomes, was linear-quadratic and similar to that observed for metaphase chromosomes. These results suggest that painting prematurely condensed chromosomes can be useful for biological dosimetry when blood samples are available shortly after the exposure, or when interphase cells are to be scored instead of mitotic cells. 32 refs., 7 figs., 1 tab.

Durante, M.; George, K.; Yang, T.C. [Lyndon B. Johnson Space Center, Houston, TX (United States)

1996-01-01

447

Mayak worker dosimetry study: An overview  

SciTech Connect

The Mayak Production Association (MPA) was the first plutonium production plant in the former Soviet Union. Workers at the MPA were exposed to relatively large internal radiation intakes and external radiation exposures, particularly in the early years of plant operations. This paper describes the updated dosimetry database, Doses-2005. Doses-2005 represents a significant improvement in the determination of absorbed organ dose from external radiation and plutonium intake for the original cohort of 18,831 Mayak workers. The methods of dose reconstruction of absorbed organ doses from external radiation uses: 1) archive records of measured dose and worker exposure history, 2) measured energy and directional response characteristics of historical Mayak film dosimeters, and 3) calculated dose conversion factors for Mayak Study-defined exposure scenarios using Monte Carlo techniques. The methods of dose reconstruction for plutonium intake uses two revised models developed from empirical data derived from bioassay and autopsy cases and/or updates from prevailing or emerging International Commission on Radiological Protection models. Other sources of potential significant exposure to workers such as medical diagnostic x-rays, ambient onsite external radiation, neutron radiation, intake of airborne effluent, and intake of nuclides other than plutonium were evaluated to determine their impact on the dose estimates.

Vasilenko, E. K.; Khokhryakov, V. F.; Miller, S C.; Fix, Jack J.; Eckerman, Keith F.; Choe, Dong Ok; Gorelov, Mikhail; Khokhryakov, Victor V.; Knyazev, V.; Krahenbuhl, Melinda P.; Scherpelz, Robert I.; Smetanin, Mikhail; Suslova, K. G.; Vostrotin, V.

2007-09-01

448

VVER-440 dosimetry and neutron spectrum benchmark  

SciTech Connect

Light Water Reactor (LWR) benchmark experiments performed in the United States under the Surveillance Dosimetry Improvement Program (SDIP), in general, reported measured reaction rates and not neutron flux spectrum. The VVER-440 benchmark experiments, using a combination of spherical hydrogen-filled proportional counters and a stilbene scintillator detector, were measurements that provided a direct verification of the transport neutron flux spectrum. The original SAILOR cross-section library from ENDF/B-IV were used, except that the iron, hydrogen, and oxygen values from ENDF/B-VI were inserted. A linear-least-squares analysis showed that the average differen