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Sample records for head volume coil

  1. Coil optimisation for transcranial magnetic stimulation in realistic head geometry.

    Science.gov (United States)

    Koponen, Lari M; Nieminen, Jaakko O; Mutanen, Tuomas P; Stenroos, Matti; Ilmoniemi, Risto J

    Transcranial magnetic stimulation (TMS) allows focal, non-invasive stimulation of the cortex. A TMS pulse is inherently weakly coupled to the cortex; thus, magnetic stimulation requires both high current and high voltage to reach sufficient intensity. These requirements limit, for example, the maximum repetition rate and the maximum number of consecutive pulses with the same coil due to the rise of its temperature. To develop methods to optimise, design, and manufacture energy-efficient TMS coils in realistic head geometry with an arbitrary overall coil shape. We derive a semi-analytical integration scheme for computing the magnetic field energy of an arbitrary surface current distribution, compute the electric field induced by this distribution with a boundary element method, and optimise a TMS coil for focal stimulation. Additionally, we introduce a method for manufacturing such a coil by using Litz wire and a coil former machined from polyvinyl chloride. We designed, manufactured, and validated an optimised TMS coil and applied it to brain stimulation. Our simulations indicate that this coil requires less than half the power of a commercial figure-of-eight coil, with a 41% reduction due to the optimised winding geometry and a partial contribution due to our thinner coil former and reduced conductor height. With the optimised coil, the resting motor threshold of abductor pollicis brevis was reached with the capacitor voltage below 600 V and peak current below 3000 A. The described method allows designing practical TMS coils that have considerably higher efficiency than conventional figure-of-eight coils. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Regulatory coiled-coil domains promote head-to-head assemblies of AAA+ chaperones essential for tunable activity control.

    Science.gov (United States)

    Carroni, Marta; Franke, Kamila B; Maurer, Michael; Jäger, Jasmin; Hantke, Ingo; Gloge, Felix; Linder, Daniela; Gremer, Sebastian; Turgay, Kürşad; Bukau, Bernd; Mogk, Axel

    2017-11-22

    Ring-forming AAA+ chaperones exert ATP-fueled substrate unfolding by threading through a central pore. This activity is potentially harmful requiring mechanisms for tight repression and substrate-specific activation. The AAA+ chaperone ClpC with the peptidase ClpP forms a bacterial protease essential to virulence and stress resistance. The adaptor MecA activates ClpC by targeting substrates and stimulating ClpC ATPase activity. We show how ClpC is repressed in its ground state by determining ClpC cryo-EM structures with and without MecA. ClpC forms large two-helical assemblies that associate via head-to-head contacts between coiled-coil middle domains (MDs). MecA converts this resting state to an active planar ring structure by binding to MD interaction sites. Loss of ClpC repression in MD mutants causes constitutive activation and severe cellular toxicity. These findings unravel an unexpected regulatory concept executed by coiled-coil MDs to tightly control AAA+ chaperone activity.

  3. Improved transcranial magnetic stimulation coil design with realistic head modeling

    Science.gov (United States)

    Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2013-03-01

    We are investigating Transcranial magnetic stimulation (TMS) as a noninvasive technique based on electromagnetic induction which causes stimulation of the neurons in the brain. TMS can be used as a pain-free alternative to conventional electroconvulsive therapy (ECT) which is still widely implemented for treatment of major depression. Development of improved TMS coils capable of stimulating subcortical regions could also allow TMS to replace invasive deep brain stimulation (DBS) which requires surgical implantation of electrodes in the brain. Our new designs allow new applications of the technique to be established for a variety of diagnostic and therapeutic applications of psychiatric disorders and neurological diseases. Calculation of the fields generated inside the head is vital for the use of this method for treatment. In prior work we have implemented a realistic head model, incorporating inhomogeneous tissue structures and electrical conductivities, allowing the site of neuronal activation to be accurately calculated. We will show how we utilize this model in the development of novel TMS coil designs to improve the depth of penetration and localization of stimulation produced by stimulator coils.

  4. Clinical usefulness of a newly-developed head and neck surface coil for MR imaging

    International Nuclear Information System (INIS)

    Shimada, Morio; Kogure, Takashi; Hayashi, Sanshin

    1995-01-01

    To obtain correct diagnosis at early stages of cervical lymph node swelling, especially cases with suspected epipharyngeal carcinoma, and cerebral arterial sclerotic diseases, high-quality MR images visualizing the entire head and neck structures and vessels are of crucial importance. When obtaining images of head and neck regions using a head coil, signal intensity (SI) and signal to noise ratio (SNR) of regions below the hypopharynx are weakened. Moreover, when obtaining images of head and neck regions using an anterior neck coil, SI and SNR of upper regions of epipharynx are also weakened. In an attempt to solve these problems, we developed a new head and neck surface coil for MR imaging. With this new coil we were able to obtain better images (153 cases) from regions below the hypopharynx to the upper regions of the epipharynx in the same time as images obtained using the head coil and anterior neck coil. 2D TOF MR angiographic images (11 cases) obtained by the head and neck surface coil are superior to 2D TOF angiographic images obtained by the anterior neck coil. MR images obtained with this improved method are valuable in the evaluation and management of head and neck region disease. (author)

  5. 96-Channel receive-only head coil for 3 Tesla: design optimization and evaluation.

    Science.gov (United States)

    Wiggins, Graham C; Polimeni, Jonathan R; Potthast, Andreas; Schmitt, Melanie; Alagappan, Vijay; Wald, Lawrence L

    2009-09-01

    The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive-only phased-array head coil with 96 receive elements constructed on a close-fitting helmet-shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal-to-noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g-factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32-channel array built on an identical helmet-shaped former and to a larger commercial 12-channel head coil. The 96-channel coil provided substantial SNR gains in the distal cortex compared to the 12- and 32-channel coils. The central SNR for the 96-channel coil was similar to the 32-channel coil for optimum SNR combination and 20% lower for root-sum-of-squares combination. There was a significant reduction in the maximum g-factor for 96 channels compared to 32; for example, the 96-channel maximum g-factor was 65% of the 32-channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images.

  6. Echo Planar Diffusion-Weighted Imaging: Possibilities and Considerations with 12- and 32-Channel Head Coils

    Directory of Open Access Journals (Sweden)

    John N Morelli

    2012-01-01

    Full Text Available Interest in clinical brain magnetic resonance imaging using 32-channel head coils for signal reception continues to increase. The present investigation assesses possibilities for improving diffusion-weighted image quality using a 32-channel in comparison to a conventional 12-channel coil. The utility of single-shot (ss and an approach to readout-segmented (rs echo planar imaging (EPI are examined using both head coils. Substantial image quality improvements are found with rs-EPI. Imaging with a 32-channel head coil allows for implementation of greater parallel imaging acceleration factors or acquisition of scans at a higher resolution. Specifically, higher resolution imaging with rs-EPI can be achieved by increasing the number of readout segments without increasing echo-spacing or echo time to the degree necessary with ss-EPI - a factor resulting in increased susceptibility artifact and reduced signal-to-noise with the latter.

  7. Short echo time proton spectroscopy of the brain in healthy volunteers using an insert gradient head coil

    DEFF Research Database (Denmark)

    Gideon, P; Danielsen, E R; Schneider, M

    1995-01-01

    An insert gradient head coil with built-in X, Y, and Z gradients was used for localized proton spectroscopy in the brain of healthy volunteers, using short echo time stimulated echo acquisition mode (STEAM) sequences. Volume of interest size was 3.4 ml, repetition time was 6.0 s, and echo times...... were 10 and 20 ms, respectively. Good quality proton spectra with practically no eddy current artefacts were acquired allowing observation of strongly coupled compounds, and compounds with short T2 relaxation times. The gradient head coil thus permits further studies of compounds such as glutamine....../glutamate and myo-inositols. These compounds were more prominent within grey matter than within white matter. Rough estimations of metabolite concentrations using water as an internal standard were in good agreement with previous reports....

  8. The lung volume reduction coil for the treatment of emphysema : a new therapy in development

    NARCIS (Netherlands)

    Klooster, Karin; ten Hacken, Nick H. T.; Slebos, Dirk-Jan

    Lung volume reduction (LVR) coil treatment is a novel therapy for patients with severe emphysema. In this bilateral bronchoscopic treatment, approximately 10 LVR coils per lobe are delivered under fluoroscopic guidance in two sequential procedures. The LVR coil reduces lung volume by compressing the

  9. Bronchoscopic Lung Volume Reduction Coil Treatment of Patients With Severe Heterogeneous Emphysema

    NARCIS (Netherlands)

    Slebos, Dirk-Jan; Klooster, Karin; Ernst, Armin; Herth, Felix J. F.; Kerstjens, Huib A. M.

    Background: The lung volume reduction coil (LVR-coil), a new experimental device to achieve lung volume reduction by bronchoscopy in patients with severe emphysema, works in a manner unaffected by collateral airflow. We investigated the safety and efficacy of LVR-coil treatment in patients with

  10. Structured Light-Based Motion Tracking in the Limited View of an MR Head Coil

    DEFF Research Database (Denmark)

    Erikshøj, M.; Olesen, Oline Vinter; Conradsen, Knut

    2013-01-01

    A markerless motion tracking (MT) system developed for use in PET brain imaging has been tested in the limited field of view (FOV) of the MR head coil from the Siemens Biograph mMR. The system is a 3D surface scanner that uses structured light (SL) to create point cloud reconstructions of the fac......A markerless motion tracking (MT) system developed for use in PET brain imaging has been tested in the limited field of view (FOV) of the MR head coil from the Siemens Biograph mMR. The system is a 3D surface scanner that uses structured light (SL) to create point cloud reconstructions...

  11. Resonant Mode Reduction in Radiofrequency Volume Coils for Ultrahigh Field Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Xiaoliang Zhang

    2011-07-01

    Full Text Available In a multimodal volume coil, only one mode can generate homogeneous Radiofrequency (RF field for Magnetic Resonance Imaging. The existence of other modes may increase the volume coil design difficulties and potentially decreases coil performance. In this study, we introduce common-mode resonator technique to high and ultrahigh field volume coil designs to reduce the resonant mode while maintain the homogeneity of the RF field. To investigate the design method, the common-mode resonator was realized by using a microstrip line which was split along the central to become a pair of parallel transmission lines within which common-mode currents exist. Eight common-mode resonators were placed equidistantly along the circumference of a low loss dielectric cylinder to form a volume coil. Theoretical analysis and comparison between the 16-strut common-mode volume coil and a conventional 16-strut volume coil in terms of RF field homogeneity and efficiency was performed using Finite-Difference Time-Domain (FDTD method at 298.2 MHz. MR imaging experiments were performed by using a prototype of the common-mode volume coil on a whole body 7 Tesla scanner. FDTD simulation results showed the reduced number of resonant modes of the common-mode volume coil over the conventional volume coil, while the RF field homogeneity of the two type volume coils was kept at the same level. MR imaging of a water phantom and a kiwi fruit showing the feasibility of the proposed method for simplifying the volume coil design is also presented.

  12. Quasi-static electric field in a cylindrical volume conductor induced by external coils.

    Science.gov (United States)

    Esselle, K P; Stuchly, M A

    1994-02-01

    An expansion technique based on modified Bessel functions is used to obtain an analytical solution for the electric field induced in a homogeneous cylindrical volume conductor by an external coil. The current in the coil is assumed to be changing slowly so that quasi-static conditions can be justified. Valid for any coil type, this solution is ideal for fast computation of the induced electric field at a large number of points. Efficient implementation of this method in a computer code is described and numerical results are presented for a perpendicular circular coil and a tangential double-square coil.

  13. On the accurate analysis of vibroacoustics in head insert gradient coils.

    Science.gov (United States)

    Winkler, Simone A; Alejski, Andrew; Wade, Trevor; McKenzie, Charles A; Rutt, Brian K

    2017-10-01

    To accurately analyze vibroacoustics in MR head gradient coils. A detailed theoretical model for gradient coil vibroacoustics, including the first description and modeling of Lorentz damping, is introduced and implemented in a multiphysics software package. Numerical finite-element method simulations were used to establish a highly accurate vibroacoustic model in head gradient coils in detail, including the newly introduced Lorentz damping effect. Vibroacoustic coupling was examined through an additional modal analysis. Thorough experimental studies were used to validate simulations. Average experimental sound pressure levels (SPLs) and accelerations over the 0-3000 Hz frequency range were 97.6 dB, 98.7 dB, and 95.4 dB, as well as 20.6 g, 8.7 g, and 15.6 g for the X-, Y-, and Z-gradients, respectively. A reasonable agreement between simulations and measurements was achieved. Vibroacoustic coupling showed a coupled resonance at 2300 Hz for the Z-gradient that is responsible for a sharp peak and the highest SPL value in the acoustic spectrum. We have developed and used more realistic multiphysics simulation methods to gain novel insights into the underlying concepts for vibroacoustics in head gradient coils, which will permit improved analyses of existing gradient coils and novel SPL reduction strategies for future gradient coil designs. Magn Reson Med 78:1635-1645, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  14. Linear versus circular polarization of head coils - comparison on phantom and in the clinic

    International Nuclear Information System (INIS)

    Schratter, M.; Kramer, J.; Prayer, L.; Wimberger, D.; Imhof, H.; Schmid, W.

    1990-01-01

    Two different head coils - one with linear polarization and the other with circular polarization - were compared under the same measurement conditions. Comparison was done on a phantom with waterfilled and gadolinium-filled pin-holes, as well as on anatomical MR images of 23 volunteers. In three volunteers the whole brain was examined while, in the remaining 20 volunteers the sella region or cerebellopontine angleregion was examined. Criteria for comparison were signal-to-noise ratio, background noise, and detail resolution (phantom), as well as subjective criteria - image sharpness, anatomical, contrast, and recognition of anatomical details -, evaluated on anatomical MR images by four radiologists independently of each other. The results show a significant improvement of signal-to-noise ratio, lower background noise and therefore marked improvement of images harpness, and moderate improvement in the recognition of anatomical details using the circular polarized head coil; as for as detail resolution and anatomical contrast were concerned, however, no significant difference was seen between the two coils. Major advantages of the circular, polarized head coil in clinical application are shorter measurement times (reduced number of acquisitions), as well as thinner slices without loss of signal-to-noise ratio. (orig.) [de

  15. Lung volume reduction coil treatment for patients with severe emphysema : a European multicentre trial

    NARCIS (Netherlands)

    Deslee, Gaetan; Klooster, Karin; Hetzel, Martin; Stanzel, Franz; Kessler, Romain; Marquette, Charles-Hugo; Witt, Christian; Blaas, Stefan; Gesierich, Wolfgang; Herth, Felix J. F.; Hetzel, Juergen; van Rikxoort, Eva M.; Slebos, Dirk-Jan

    2014-01-01

    Background The lung volume reduction (LVR) coil is a minimally invasive bronchoscopic nitinol device designed to reduce hyperinflation and improve elastic recoil in severe emphysema. We investigated the feasibility, safety and efficacy of LVR coil treatment in a prospective multicentre cohort trial

  16. SAR and thermal response effects of a two-arm Archimedean spiral coil in a magnetic induction sensor on a human head.

    Science.gov (United States)

    Zhang, Ziyi; Liu, Peiguo; Zhou, Dongming; Zhang, Liang; Ding, Liang

    2015-01-01

    This study investigates the radiation safety of a newly designed magnetic induction sensor. This novel magnetic induction sensor uses a two-arm Archimedean spiral coil (TAASC) as the exciter. A human head model with a real anatomical structure was used to calculate the specific absorption rate (SAR) and temperature change. Computer Simulation Technology (CST) was used to determine the values of the peak 10-g SAR under different operating parameters (current, frequency, horizontal distance between the excitation coil and the receiver coil, vertical distance between the top of the head model and the XOY plane, position of excitation coil, and volume of hemorrhage). Then, the highest response for the SAR and temperature rise was determined. The results showed that this new magnetic induction sensor is safe in the initial state; for safety reasons, the TAASC current should not exceed 4 A. The scalp tissue absorbed most of the electromagnetic energy. The TAASC's SAR/thermal performance was close to that of the circular coil.

  17. Susceptibility Imaging in Glial Tumor Grading; Using 3 Tesla Magnetic Resonance (MR) System and 32 Channel Head Coil.

    Science.gov (United States)

    Aydin, Omer; Buyukkaya, Ramazan; Hakyemez, Bahattin

    2017-01-01

    Susceptibility weighted imaging (SWI) is a velocity compensated, high-resolution three-dimensional (3D) spoiled gradient-echo sequence that uses magnitude and filtered-phase data. SWI seems to be a valuable tool for non-invasive evaluation of central nervous system gliomas. Relative cerebral blood volume (rCBV) ratio is one of the best noninvasive methods for glioma grading. Degree of intratumoral susceptibility signal (ITSS) on SWI correlates with rCBV ratio and histopathological grade. This study investigated the effectiveness of ITSS grading and rCBV ratio in preoperative assessment. Thirty-one patients (17 males and 14 females) with histopathogical diagnosis of glial tumor undergoing routine cranial MRI, SWI, and perfusion MRI examinations between October 2011 and July 2013 were retrospectively enrolled. All examinations were performed using 3T apparatus with 32-channel head coil. We used ITSS number for SWI grading. Correlations between SWI grade, rCBV ratio, and pathological grading were evaluated. ROC analysis was performed to determine the optimal rCBV ratio to distinguish between high-grade and low-grade glial tumors. There was a strong positive correlation between both pathological and SWI grading. We determined the optimal rCBV ratio to discriminate between high-grade and low-grade tumors to be 2.21. In conclusion, perfusion MRI and SWI using 3T MR and 32-channel head coil may provide useful information for preoperative glial tumor grading. SWI can be used as an accessory to perfusion MR technique in preoperative tumor grading.

  18. 3D 1H MRSI of brain tumors at 3.0 Tesla using an eight-channel phased-array head coil.

    Science.gov (United States)

    Osorio, Joseph A; Ozturk-Isik, Esin; Xu, Duan; Cha, Soonmee; Chang, Susan; Berger, Mitchel S; Vigneron, Daniel B; Nelson, Sarah J

    2007-07-01

    To implement proton magnetic resonance spectroscopic imaging (1H MRSI) at 3 Tesla (3T) using an eight-channel phased-array head coil in a population of brain-tumor patients. A total of 49 MRI/MRSI examinations were performed on seven volunteers and 34 patients on a 3T GE Signa EXCITE scanner using body coil excitation and reception with an eight-channel phased-array head coil. 1H MRSI was acquired using point-resolved spectroscopy (PRESS) volume selection and three-dimensional (3D) phase encoding using a 144-msec echo time (TE). The mean choline to N-acetyl aspartate ratio (Cho/NAA) was similar within regions of normal-appearing white matter (NAWM) in volunteers (0.5 +/- 0.04) and patients (0.6 +/- 0.1, P = 0.15). This ratio was significantly higher in regions of T2-hyperintensity lesion (T2L) relative to NAWM for patients (1.4 +/- 0.7, P = 0.001). The differences between metabolite intensities in lesions and NAWM were similar, but there was an increase in SNR of 1.95 when an eight-channel head coil was used at 3T vs. previous results at 1.5T. The realized increase in SNR means that clinically relevant data can be obtained in five to 10 minutes at 3T and used to predict the spatial extent of tumor in a manner similar to that previously used to acquire 1.5T data in 17 minutes. Copyright 2007 Wiley-Liss, Inc.

  19. Treatment of emphysema using bronchoscopic lung volume reduction coil technology : an update on efficacy and safety

    NARCIS (Netherlands)

    Hartman, Jorine E.; Klooster, Karin; ten Hacken, Nick H. T.; Slebos, Dirk-Jan

    2015-01-01

    In the last decade several promising bronchoscopic lung volume reduction (BLVR) treatments were developed and investigated. One of these treatments is BLVR treatment with coils. The advantage of this specific treatment is that it works independently of collateral flow, and also shows promise for

  20. 32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry.

    Science.gov (United States)

    Wiggins, G C; Triantafyllou, C; Potthast, A; Reykowski, A; Nittka, M; Wald, L L

    2006-07-01

    A 32-channel 3T receive-only phased-array head coil was developed for human brain imaging. The helmet-shaped array was designed to closely fit the head with individual overlapping circular elements arranged in patterns of hexagonal and pentagonal symmetry similar to that of a soccer ball. The signal-to-noise ratio (SNR) and noise amplification (g-factor) in accelerated imaging applications were quantitatively evaluated in phantom and human images and compared with commercially available head coils. The 32-channel coil showed SNR gains of up to 3.5-fold in the cortex and 1.4-fold in the corpus callosum compared to a (larger) commercial eight-channel head coil. The experimentally measured g-factor performance of the helmet array showed significant improvement compared to the eight-channel array (peak g-factor 59% and 26% of the eight-channel values for four- and fivefold acceleration). The performance of the arrays is demonstrated in high-resolution and highly accelerated brain images. Copyright (c) 2006 Wiley-Liss, Inc.

  1. Comparison of a 28 Channel-Receive Array Coil and Quadrature Volume Coil for Morphologic Imaging and T2 Mapping of Knee Cartilage at 7 Tesla

    Science.gov (United States)

    Chang, Gregory; Wiggins, Graham C.; Xia, Ding; Lattanzi, Riccardo; Madelin, Guillaume; Raya, Jose G.; Finnerty, Matthew; Fujita, Hiroyuki; Recht, Michael P.; Regatte, Ravinder R.

    2011-01-01

    Purpose To compare a new birdcage-transmit, 28 channel-receive array (28 Ch) coil and a quadrature volume coil for 7 Tesla morphologic MRI and T2 mapping of knee cartilage. Methods The right knees of ten healthy subjects were imaged on a 7 Tesla whole body MR scanner using both coils. 3-dimensional fast low-angle shot (3D-FLASH) and multi-echo spin-echo (MESE) sequences were implemented. Cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), thickness, and T2 values were assessed. Results SNR/CNR was 17–400% greater for the 28 Ch compared to the quadrature coil (p≤0.005). Bland-Altman plots show mean differences between measurements of tibial/femoral cartilage thickness and T2 values obtained with each coil to be small (−0.002±0.009 cm/0.003±0.011 cm) and large (−6.8±6.7 ms/−8.2±9.7 ms), respectively. For the 28 Ch coil, when parallel imaging with acceleration factors (AF) 2, 3, and 4 was performed, SNR retained was: 62–69%, 51–55%, and 39–45%. Conclusion A 28 Ch knee coil provides increased SNR/CNR for 7T cartilage morphologic imaging and T2 mapping. Coils should be switched with caution during clinical studies because T2 values may differ. The greater SNR of the 28 Ch coil could be used to perform parallel imaging with AF2 and obtain similar SNR as the quadrature coil. PMID:22095723

  2. Theoretical study for volume changes associated with the helix-coil transition of peptides.

    Science.gov (United States)

    Imai, T; Harano, Y; Kovalenko, A; Hirata, F

    2001-12-01

    We calculate the partial molar volumes and their changes associated with the coil(extended)-to-helix transition of two types of peptide, glycine-oligomer and glutamic acid-oligomer, in aqueous solutions by using the Kirkwood-Buff solution theory coupled with the three-dimensional reference interaction site model (3D-RISM) theory. The volume changes associated with the transition are small and positive. The volume is analyzed by decomposing it into five contributions following the procedure proposed by Chalikian and Breslauer: the ideal volume, the van der Waals volume, the void volume, the thermal volume, and the interaction volume. The ideal volumes and the van der Waals volumes do not change appreciably upon the transition. In the both cases of glycine-peptide and glutamic acid-peptide, the changes in the void volumes are positive, while those in the thermal volumes are negative, and tend to balance those in the void volumes. The change in the interaction volume of glycine-peptide does not significantly contribute, while that of glutamic acid-peptide makes a negative contribution. Copyright 2001 John Wiley & Sons, Inc. Biopolymers 59: 512-519, 2001

  3. Whole Prostate Volume and Shape Changes with the Use of an Inflatable and Flexible Endorectal Coil

    International Nuclear Information System (INIS)

    Osman, M.; Shebel, H.; Sankineni, S.; Bernardo, M.L.; Daar, D.; Choyke, P.L.; Turkbey, B.; Agarwal, H.K.; Osman, M.; Shebel, H.; Bernardo, M.L.; Wood, P.J.; Pinto, P.A.; Agarwal, H.K.

    2014-01-01

    To determine to what extent an inflatable endorectal coil (ERC) affects whole prostate (WP) volume and shape during prostate MRI. Materials and Methods. 79 consecutive patients underwent T2W MRI at 3T first with a 6-channel surface coil and then with the combination of a 16-channel surface coil and ERC in the same imaging session. WP volume was assessed by manually contouring the prostate in each T2W axial slice. PSA density was also calculated. The maximum anterior-posterior (AP), left-right (LR), and cranio caudal (CC) prostate dimensions were measured. Changes in WP prostate volume, PSA density, and prostate dimensions were then evaluated. Results. In 79 patients, use of an ERC yielded no significant change in whole prostate volume (0.6 ± 5.7 %, Ρ=0.270) and PSA density (-0.2 ±5.6%,Ρ=0.768 ). However, use of an ERC significantly decreased the AP dimension of the prostate by -8.6 ±7.8%(Ρ<0.001), increased LR dimension by 4.5 ± 5.8 %(Ρ<0.001), and increased the CC dimension by 8.8 ±6.9 %( Ρ<0.001). Conclusion. Use of an ERC in prostate MRI results in the shape deformation of the prostate gland with no significant change in the volume of the prostate measured on T2W MRI. Therefore, WP volumes calculated on ERC MRI can be reliably used in clinical work flow.

  4. Lung Volume Reduction Coil Treatment in Chronic Obstructive Pulmonary Disease Patients with Homogeneous Emphysema : A Prospective Feasibility Trial

    NARCIS (Netherlands)

    Klooster, Karin; ten Hacken, Nick H. T.; Franz, Ina; Kerstjens, Huib A. M.; van Rikxoort, Eva M.; Slebos, Dirk-Jan

    2014-01-01

    Background: In patients with heterogeneous emphysema, surgical and bronchoscopic lung volume reduction (LVR) treatments are available. However, for patients with homogeneous emphysema these treatments are hardly investigated and seem less effective. Bronchoscopic LVR coil treatment has been shown to

  5. A novel analytical description of periodic volume coil geometries in MRI

    Science.gov (United States)

    Koh, D.; Felder, J.; Shah, N. J.

    2018-03-01

    MRI volume coils can be represented by equivalent lumped element circuits and for a variety of these circuit configurations analytical design equations have been presented. The unification of several volume coil topologies results in a two-dimensional gridded equivalent lumped element circuit which compromises the birdcage resonator, its multiple endring derivative but also novel structures like the capacitive coupled ring resonator. The theory section analyzes a general two-dimensional circuit by noting that its current distribution can be decomposed into a longitudinal and an azimuthal dependency. This can be exploited to compare the current distribution with a transfer function of filter circuits along one direction. The resonances of the transfer function coincide with the resonance of the volume resonator and the simple analytical solution can be used as a design equation. The proposed framework is verified experimentally against a novel capacitive coupled ring structure which was derived from the general circuit formulation and is proven to exhibit a dominant homogeneous mode. In conclusion, a unified analytical framework is presented that allows determining the resonance frequency of any volume resonator that can be represented by a two dimensional meshed equivalent circuit.

  6. Contrast-enhanced MR venography of the head using magnetization prepared rapid gradient echo imaging. Comparison between head and body radiofrequency transmitter coil systems

    International Nuclear Information System (INIS)

    Matsunobu, Satosi; Amanuma, Makoto; Tsukuda, Shunji

    2004-01-01

    The purpose of this study was to evaluate the image quality and vascular selectivity of MR venography of the head using an magnetization prepared rapid gradient echo (MP-RAGE) technique when obtained with a body radiofrequency transmitter coil system. A total of 24 patients were imaged with a head or body radiofrequency (RF) transmission system. Subtraction MR angiography (MRA) was processed with 0.1 mmol Gd-DTPA administration, and signal-to-noise ratios of the vascular system were measured. Venous demonstration and selectivity were also assessed. MP-RAGE MR venography with a body transmission system showed almost the same signal intensity for the venous and arterial systems, resulting in nonspecific vascular demonstration, while the head transmission system showed semi-selective venograms owing to inflow-induced high signal on precontrast images. However, MRA with a body transmission system provided a 1.5- to 2.5-fold higher signal-to-noise ratios based on higher gradient performance and excellent demonstration of the head veins, especially those below the skull base. Although selective venography was difficult, MRA with a body transmission coil provided excellent vascular images of the brain. (author)

  7. Evaluation of a 32-channel versus a 12-channel head coil for high-resolution post-contrast MRI in giant cell arteritis (GCA) at 3 T

    Energy Technology Data Exchange (ETDEWEB)

    Franke, Philipp, E-mail: philipp.franke@uniklinik-freiburg.de [Institut für Diagnostische Radiologie, Gartenstr. 28, 79098 Freiburg (Germany); Markl, Michael, E-mail: mmarkl@northwestern.edu [Departments of Radiology and Biomedical Engineering, Northwestern University Chicago, 737 North Michigan Avenue, Suite 1600, Chicago, IL 60611 (United States); Heinzelmann, Sonja, E-mail: sonja.heinzelmann@uniklinik-freiburg.de [Department of Ophthalmology, University Hospital Freiburg, Killianstr. 5, 79106 Freiburg (Germany); Vaith, Peter, E-mail: peter.vaith@uniklinik-freiburg.de [Department of Rheumatology and Immunology, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg (Germany); Bürk, Jonas, E-mail: jonas.buerk@uniklinik-freiburg.de [Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg (Germany); Langer, Mathias, E-mail: mathias.langer@uniklinik-freiburg.de [Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg (Germany); Geiger, J., E-mail: julia.geiger@uniklinik-freiburg.de [Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg (Germany); Department of Radiology, University Children‘s Hospital Zurich, Steinwiesstr. 75, 8032 Zurich (Switzerland)

    2014-10-15

    The aim of this study was to evaluate the diagnostic value of a 32-channel head coil for the characterization of mural inflammation patterns in the superficial cranial arteries in patients with giant cell arteritis (GCA) compared to a standard 12-channel coil at 3 T MRI. 55 patients with suspected GCA underwent high resolution T1-weighted post-contrast MRI at 3 T to detect inflammation related vessel wall enhancement using both coils. To account for different time delays between contrast agent injection and sequence acquisition, the patients were divided into two cohorts: 27 patients were examined with the 32-channel coil first and 28 patients with the 12-channel coil first. Images were evaluated by two blinded readers with regard to image quality, artifact level and arteries’ inflammation according to a standardized ranking scale; furthermore signal-to-noise ratio (SNR) measurements were performed at three locations. Identification of arteries’ inflammation was achieved with both coils with excellent inter-observer agreement (κ = 0.89 for 12-channel and κ = 0.96 for 32-channel coil). Regarding image grading, the inter-observer variability was moderate for the 12-channel (κ = 0.5) and substantial for the 32-channel coil (κ = 0.63). Significantly higher SNR and improved image quality (p < 0.01) were obtained with the 32-channel coil in either coil order. Image quality for depiction of the superficial cranial arteries was superior for the 32-channel coil. For standardized GCA diagnosis, the 12-channel coil was sufficient.

  8. Resting-state networks in healthy adult subjects: a comparison between a 32-element and an 8-element phased array head coil at 3.0 Tesla.

    Science.gov (United States)

    Paolini, Marco; Keeser, Daniel; Ingrisch, Michael; Werner, Natalie; Kindermann, Nicole; Reiser, Maximilian; Blautzik, Janusch

    2015-05-01

    Little research exists on the influence of a magnetic resonance imaging (MRI) head coil's channel count on measured resting-state functional connectivity. To compare a 32-element (32ch) and an 8-element (8ch) phased array head coil with respect to their potential to detect functional connectivity within resting-state networks. Twenty-six healthy adults (mean age, 21.7 years; SD, 2.1 years) underwent resting-state functional MRI at 3.0 Tesla with both coils using equal standard imaging parameters and a counterbalanced design. Independent component analysis (ICA) at different model orders and a dual regression approach were performed. Voxel-wise non-parametric statistical between-group contrasts were determined using permutation-based non-parametric inference. Phantom measurements demonstrated a generally higher image signal-to-noise ratio using the 32ch head coil. However, the results showed no significant differences between corresponding resting-state networks derived from both coils (p coil does not offer any significant advantages in detecting ICA-based functional connectivity within RSNs. © The Foundation Acta Radiologica 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  9. 3 Tesla MRI of patients with a vagus nerve stimulator: initial experience using a T/R head coil under controlled conditions.

    Science.gov (United States)

    Gorny, Krzysztof R; Bernstein, Matt A; Watson, Robert E

    2010-02-01

    To assess safety of clinical MRI of the head in patients with implanted model 100, 102, and 103 vagus nerve stimulation (VNS) Therapy Systems (Cyberonics, Inc., Houston, TX) in 3.0 Tesla MRI (GE Healthcare, Milwaukee, WI). The distributions of the radiofrequency B(1) (+)-field produced by the clinically used transmit/receive (T/R) head coil (Advanced Imaging Research Incorporated, Cleveland, OH) and body coil were measured in a head and shoulders phantom. These measurements were supplemented by temperature measurements on the lead tips and the implantable pulse generator (IPG) of the VNS devices in a head and torso phantom with the same two coils. Clinical 3T MRI head scans were then acquired under highly controlled conditions in a series of 17 patients implanted with VNS. Phantom studies showed only weak B(1) (+) fields at the location of the VNS IPG and leads for MRI scans using the T/R head coil. The MRI-related heating on a VNS scanned in vitro at 3T was also found to be minimal (0.4-0.8 degrees C at the leads, negligible at the IPG). The patient MRI examinations were completed successfully without any adverse incidents. No patient reported any heating, discomfort, or any other unusual sensation. Safe clinical MRI head scanning of patients with implanted VNS is shown to be feasible on a GE Signa Excite 3T MRI system using one specific T/R head coil. These results apply to this particular MRI system configuration. Extrapolation or generalization of these results to more general or less controlled imaging situations without supporting data of safety is highly discouraged.

  10. Is the Ellipsoid Formula the New Standard for 3-Tesla MRI Prostate Volume Calculation without Endorectal Coil?

    Science.gov (United States)

    Haas, Matthias; Günzel, Karsten; Miller, Kurt; Hamm, Bernd; Cash, Hannes; Asbach, Patrick

    2017-01-01

    Prostate volume in multiparametric MRI (mpMRI) is of clinical importance. For 3-Tesla mpMRI without endorectal coil, there is no distinctive standard for volume calculation. We tested the accuracy of the ellipsoid formula with planimetric volume measurements as reference and investigated the correlation of gland volume and cancer detection rate on MRI/ultrasound (MRI/US) fusion-guided biopsy. One hundred forty-three patients with findings on 3-Tesla mpMRI suspicious of cancer and subsequent MRI/US fusion-guided targeted biopsy and additional systematic biopsy were analyzed. T2-weighted images were used for measuring the prostate diameters and for planimetric volume measurement by a segmentation software. Planimetric and calculated prostate volumes were compared with clinical data. The median prostate volume was 48.1 ml (interquartile range (IQR) 36.9-62.1 ml). Volume calculated by the ellipsoid formula showed a strong concordance with planimetric volume, with a tendency to underestimate prostate volume (median volume 43.1 ml (IQR 31.2-58.8 ml); r = 0.903, p Tesla mpMRI without endorectal coil. It allows a fast, valid volume calculation in prostate MRI datasets. © 2016 S. Karger AG, Basel.

  11. Quadruple Cone Coil with improved focality than Figure-8 coil in Transcranial Magnetic Stimulation

    Science.gov (United States)

    Rastogi, Priyam; Lee, Erik G.; Hadimani, Ravi L.; Jiles, David C.

    Transcranial Magnetic Stimulation (TMS) is a non-invasive therapy which uses a time varying magnetic field to induce an electric field in the brain and to cause neuron depolarization. Magnetic coils play an important role in the TMS therapy since their coil geometry determines the focality and penetration's depth of the induced electric field in the brain. Quadruple Cone Coil (QCC) is a novel coil with an improved focality when compared to commercial Figure-8 coil. The results of this newly designed QCC coil are compared with the Figure-8 coil at two different positions of the head - vertex and dorsolateral prefrontal cortex, over the 50 anatomically realistic MRI derived head models. Parameters such as volume of stimulation, maximum electric, area of stimulation and location of maximum electric field are determined with the help of computer modelling of both coils. There is a decrease in volume of brain stimulated by 11.6 % and a modest improvement of 8 % in the location of maximum electric field due to QCC in comparison to the Figure-8 coil. The Carver Charitable Trust and The Galloway Foundation.

  12. Functional Laterality of Task-Evoked Activation in Sensorimotor Cortex of Preterm Infants: An Optimized 3 T fMRI Study Employing a Customized Neonatal Head Coil.

    Science.gov (United States)

    Scheef, Lukas; Nordmeyer-Massner, Jurek A; Smith-Collins, Adam Pr; Müller, Nicole; Stegmann-Woessner, Gaby; Jankowski, Jacob; Gieseke, Jürgen; Born, Mark; Seitz, Hermann; Bartmann, Peter; Schild, Hans H; Pruessmann, Klaas P; Heep, Axel; Boecker, Henning

    2017-01-01

    Functional magnetic resonance imaging (fMRI) in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD) responses in sensorimotor cortex (SMC). Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level. Here, we employed a custom-designed neonatal MR-coil adapted and optimized to the head size of a newborn in order to improve robustness, reliability and validity of neonatal sensorimotor fMRI. Thirteen preterm infants with a median gestational age of 26 weeks were scanned at term-corrected age using a prototype 8-channel neonatal head coil at 3T (Achieva, Philips, Best, NL). Sensorimotor stimulation was elicited by passive extension/flexion of the elbow at 1 Hz in a block design. Analysis of temporal signal to noise ratio (tSNR) was performed on the whole brain and the SMC, and was compared to data acquired with an 'adult' 8 channel head coil published previously. Task-evoked activation was determined by single-subject SPM8 analyses, thresholded at p lateralization of SMC activation, as found in children and adults, is already present in the newborn period.

  13. A Specialized Multi-Transmit Head Coil for High Resolution fMRI of the Human Visual Cortex at 7T.

    Science.gov (United States)

    Sengupta, Shubharthi; Roebroeck, Alard; Kemper, Valentin G; Poser, Benedikt A; Zimmermann, Jan; Goebel, Rainer; Adriany, Gregor

    2016-01-01

    To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. A 4 channel transmit and 16 channel receive array was constructed on a conformal polycarbonate former. Transmit field efficiency and homogeneity were simulated and validated, along with the Specific Absorption Rate, using [Formula: see text] mapping techniques and electromagnetic simulations. Receiver signal-to-noise ratio (SNR), temporal SNR (tSNR) across EPI time series, g-factors for accelerated imaging and noise correlations were evaluated and compared with a commercial 32 channel whole head coil. The performance of the coil was further evaluated with human subjects through functional MRI (fMRI) studies at standard and submillimeter resolutions of upto 0.8mm isotropic. The transmit and receive sections were characterized using bench tests and showed good interelement decoupling, preamplifier decoupling and sample loading. SNR for the 16 channel coil was ∼ 1.5 times that of the commercial coil in the human occipital lobe, and showed better g-factor values for accelerated imaging. fMRI tests conducted showed better response to Blood Oxygen Level Dependent (BOLD) activation, at resolutions of 1.2mm and 0.8mm isotropic. The 4 channel phased array transmit coil provides homogeneous excitation across the visual cortex, which, in combination with the dual row 16 channel receive array, makes for a valuable research tool for high resolution anatomical and functional imaging of the visual cortex at 7T.

  14. Optimum coil shape for a given volume of conductor to obtain maximum central field in an air core solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, P. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    This paper is an expansion of engineering notes prepared in 1961 to address the question of how to wind circular coils so as to obtain the maximum axial field with the minimum volume of conductor. At the time this was a germain question because of the advent of superconducting wires which were in very limited supply, and the rapid push for generation of very high fields, with little concern for uniformity.

  15. Functional Laterality of Task-Evoked Activation in Sensorimotor Cortex of Preterm Infants: An Optimized 3 T fMRI Study Employing a Customized Neonatal Head Coil.

    Directory of Open Access Journals (Sweden)

    Lukas Scheef

    Full Text Available Functional magnetic resonance imaging (fMRI in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD responses in sensorimotor cortex (SMC. Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level.Here, we employed a custom-designed neonatal MR-coil adapted and optimized to the head size of a newborn in order to improve robustness, reliability and validity of neonatal sensorimotor fMRI. Thirteen preterm infants with a median gestational age of 26 weeks were scanned at term-corrected age using a prototype 8-channel neonatal head coil at 3T (Achieva, Philips, Best, NL. Sensorimotor stimulation was elicited by passive extension/flexion of the elbow at 1 Hz in a block design. Analysis of temporal signal to noise ratio (tSNR was performed on the whole brain and the SMC, and was compared to data acquired with an 'adult' 8 channel head coil published previously. Task-evoked activation was determined by single-subject SPM8 analyses, thresholded at p < 0.05, whole-brain FWE-corrected.Using a custom-designed neonatal MR-coil, we found significant positive BOLD responses in contralateral SMC after unilateral passive sensorimotor stimulation in all neonates (analyses restricted to artifact-free data sets = 8/13. Improved imaging characteristics of the neonatal MR-coil were evidenced by additional phantom and in vivo tSNR measurements: phantom studies revealed a 240% global increase in tSNR; in vivo studies revealed a 73% global and a 55% local (SMC increase in tSNR, as compared to the 'adult' MR-coil.Our findings strengthen the

  16. Transcranial Magnetic Stimulation-coil design with improved focality

    Science.gov (United States)

    Rastogi, P.; Lee, E. G.; Hadimani, R. L.; Jiles, D. C.

    2017-05-01

    Transcranial Magnetic Stimulation (TMS) is a technique for neuromodulation that can be used as a non-invasive therapy for various neurological disorders. In TMS, a time varying magnetic field generated from an electromagnetic coil placed on the scalp is used to induce an electric field inside the brain. TMS coil geometry plays an important role in determining the focality and depth of penetration of the induced electric field responsible for stimulation. Clinicians and basic scientists are interested in stimulating a localized area of the brain, while minimizing the stimulation of surrounding neural networks. In this paper, a novel coil has been proposed, namely Quadruple Butterfly Coil (QBC) with an improved focality over the commercial Figure-8 coil. Finite element simulations were conducted with both the QBC and the conventional Figure-8 coil. The two coil's stimulation profiles were assessed with 50 anatomically realistic MRI derived head models. The coils were positioned on the vertex and the scalp over the dorsolateral prefrontal cortex to stimulate the brain. Computer modeling of the coils has been done to determine the parameters of interest-volume of stimulation, maximum electric field, location of maximum electric field and area of stimulation across all 50 head models for both coils.

  17. Increased cerebellar gray matter volume in head chefs.

    Directory of Open Access Journals (Sweden)

    Antonio Cerasa

    Full Text Available Chefs exert expert motor and cognitive performances on a daily basis. Neuroimaging has clearly shown that that long-term skill learning (i.e., athletes, musicians, chess player or sommeliers induces plastic changes in the brain thus enabling tasks to be performed faster and more accurately. How a chef's expertise is embodied in a specific neural network has never been investigated.Eleven Italian head chefs with long-term brigade management expertise and 11 demographically-/ psychologically- matched non-experts underwent morphological evaluations.Voxel-based analysis performed with SUIT, as well as, automated volumetric measurement assessed with Freesurfer, revealed increased gray matter volume in the cerebellum in chefs compared to non-experts. The most significant changes were detected in the anterior vermis and the posterior cerebellar lobule. The magnitude of the brigade staff and the higher performance in the Tower of London test correlated with these specific gray matter increases, respectively.We found that chefs are characterized by an anatomical variability involving the cerebellum. This confirms the role of this region in the development of similar expert brains characterized by learning dexterous skills, such as pianists, rock climbers and basketball players. However, the nature of the cellular events underlying the detected morphological differences remains an open question.

  18. An 8/15-channel Tx/Rx head neck RF coil combination with region-specific B1 + shimming for whole-brain MRI focused on the cerebellum at 7T.

    Science.gov (United States)

    Pfaffenrot, Viktor; Brunheim, Sascha; Rietsch, Stefan H G; Koopmans, Peter J; Ernst, Thomas M; Kraff, Oliver; Orzada, Stephan; Quick, Harald H

    2018-02-09

    To design and evaluate an 8/15-channel transmit/receive (Tx/Rx) head-neck RF coil combination with region-specific B1+ shimming for whole-brain MRI with focus on improved functional MRI of the cerebellum at 7 T. An 8-channel transceiver RF head coil was combined with a 7-channel receive-only array. The noise parameters and acceleration capabilities of this 8Tx/15Rx coil setup were compared with a commercially available 1Tx/32Rx RF head coil. Region-specific 8-channel B1+ shimming was applied when using the 8Tx/15Rx RF coil. To evaluate the capability for functional MRI of the cerebellum, temporal SNR and statistical nonparametric maps for finger-tapping experiments with 14 healthy subjects were derived by applying a variable slice thickness gradient-echo echo-planar functional MRI sequence. The 8Tx/15Rx setup had a lower maximum noise correlation between channels, but higher average correlations compared with the 1Tx/32Rx coil. Both RF coils exhibited identical g-factors in the cerebellum with R = 3 acceleration. The enlarged FOV of the 8Tx/15Rx coil in combination with region-specific B1+ shimming increased homogeneity of the transmission field and temporal SNR in caudal cerebellar regions. Temporal SNR losses in cranial parts were reduced, resulting in more highly significant voxels in the caudally activated areas and identical patterns in the cranial cerebellar parts during a finger-tapping task. Compared with the 1Tx/32Rx RF coil, the presented 8Tx/15Rx RF coil combination successfully improves functional MRI of the human cerebellum at 7 T while maintaining whole-brain coverage. A clear temporal SNR gain in caudal cerebellar regions is shown. © 2018 International Society for Magnetic Resonance in Medicine.

  19. Impact of endobronchial coiling on segmental bronchial lumen in treated and untreated lung lobes: Correlation with changes in lung volume, clinical and pulmonary function tests.

    Science.gov (United States)

    Kloth, C; Thaiss, W M; Hetzel, J; Ditt, H; Grosse, U; Nikolaou, K; Horger, M

    2016-07-01

    To assess the impact of endobronchial coiling on the segment bronchus cross-sectional area and volumes in patients with lung emphysema using quantitative chest-CT measurements. Thirty patients (female = 15; median age = 65.36 years) received chest-CT before and after endobronchial coiling for lung volume reduction (LVR) between January 2010 and December 2014. Thin-slice (0.6 mm) non-enhanced image data sets were acquired both at end-inspiration and end-expiration using helical technique and 120 kV/100-150 mAs. Clinical response was defined as an increase in the walking distance (Six-minute walk test; 6MWT) after LVR-therapy. Additionally, pulmonary function test (PFT) measurements were used for clinical correlation. In the treated segmental bronchia, the cross-sectional lumen area showed significant reduction (p  0.05). In the ipsilateral lobes, the lumina showed no significant changes. In the contralateral lung, we found tendency towards increased cross-sectional area in inspiration (p = 0.06). Volumes of the treated segments correlated with the treated segmental bronchial lumina in expiration (r = 0.80, p volume of the treated lobe in responders only. Endobronchial coiling causes significant decrease in the cross-sectional area of treated segment bronchi in inspiration and a slight increase in expiration accompanied by a volume reduction. • Endobronchial coiling has indirect impact on cross-sectional area of treated segment bronchi • Volume changes of treated lobes correlate with changes in bronchial cross-sectional area • Coil-induced effects reflect their stabilizing and stiffening impact on lung parenchyma • Endobronchial coiling reduces bronchial collapsing compensating the loss of elasticity.

  20. NMR measurement of dynamic nuclear polarization: a technique to test the quality of its volume average obtained with different NMR coil configurations

    International Nuclear Information System (INIS)

    Zhao, W.H.; Cox, S.F.J.

    1980-07-01

    In the NMR measurement of dynamic nuclear polarization, a volume average is obtained where the contribution from different parts of the sample is weighted according to the local intensity of the RF field component perpendicular to the large static field. A method of mapping this quantity is described. A small metallic object whose geometry is chosen to perturb the appropriate RF component is scanned through the region to be occupied by the sample. The response of the phase angle of the impedance of a tuned circuit comprising the NMR coil gives a direct measurement of the local weighting factor. The correlation between theory and experiment was obtained by using a circular coil. The measuring method, checked in this way, was then used to investigate the field profiles of practical coils which are required to be rectangular for a proposed experimental neutron polarizing filter. This method can be used to evaluate other practical RF coils. (author)

  1. DIPA-family coiled-coils bind conserved isoform-specific head domain of p120-catenin family: potential roles in hydrocephalus and heterotopia.

    Science.gov (United States)

    Markham, Nicholas O; Doll, Caleb A; Dohn, Michael R; Miller, Rachel K; Yu, Huapeng; Coffey, Robert J; McCrea, Pierre D; Gamse, Joshua T; Reynolds, Albert B

    2014-09-01

    p120-catenin (p120) modulates adherens junction (AJ) dynamics by controlling the stability of classical cadherins. Among all p120 isoforms, p120-3A and p120-1A are the most prevalent. Both stabilize cadherins, but p120-3A is preferred in epithelia, whereas p120-1A takes precedence in neurons, fibroblasts, and macrophages. During epithelial-to-mesenchymal transition, E- to N-cadherin switching coincides with p120-3A to -1A alternative splicing. These isoforms differ by a 101-amino acid "head domain" comprising the p120-1A N-terminus. Although its exact role is unknown, the head domain likely mediates developmental and cancer-associated events linked to p120-1A expression (e.g., motility, invasion, metastasis). Here we identified delta-interacting protein A (DIPA) as the first head domain-specific binding partner and candidate mediator of isoform 1A activity. DIPA colocalizes with AJs in a p120-1A- but not 3A-dependent manner. Moreover, all DIPA family members (Ccdc85a, Ccdc85b/DIPA, and Ccdc85c) interact reciprocally with p120 family members (p120, δ-catenin, p0071, and ARVCF), suggesting significant functional overlap. During zebrafish neural tube development, both knockdown and overexpression of DIPA phenocopy N-cadherin mutations, an effect bearing functional ties to a reported mouse hydrocephalus phenotype associated with Ccdc85c. These studies identify a novel, highly conserved interaction between two protein families that may participate either individually or collectively in N-cadherin-mediated development. © 2014 Markham et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  2. Advances in otolaryngology-Head and neck surgery. Volume 1

    International Nuclear Information System (INIS)

    Myers, E.N.; Bluestone, C.D.

    1987-01-01

    This book consists of 14 sections. The section titles are: The impact of AIDS on otolaryngology--head and neck surgery; The management of sleep apneas and snoring; Antimicrobial agents for infections in the ear, nose, and throat--head and neck; Nasal allergy: Medical and surgical treatment; Uses of computerized tomography and magnetic resonance imaging in temporal bone imaging; Surgical management of otitis media with effusion; middle ear reconstruction: Current status; Cochlear implants: an overview; Diagnosis and management of acute facial paralysis; The use of the laser in head and neck surgery; The management and prevention of subglottic stenosis in infants and children; Management of the mass in the thyroid; Suction-assisted lipectomy of the head and neck area; and Ambulatory surgery

  3. Advances in otolaryngology-Head and neck surgery. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Myers, E.N. (Univ. of Pittsburgh School of Medicine, Pittsburgh, PA (US)); Bluestone, C.D. (Univ. of Pittsburgh, Pittsburgh, PA (US))

    1987-01-01

    This book consists of 14 sections. The section titles are: The impact of AIDS on otolaryngology--head and neck surgery; The management of sleep apneas and snoring; Antimicrobial agents for infections in the ear, nose, and throat--head and neck; Nasal allergy: Medical and surgical treatment; Uses of computerized tomography and magnetic resonance imaging in temporal bone imaging; Surgical management of otitis media with effusion; middle ear reconstruction: Current status; Cochlear implants: an overview; Diagnosis and management of acute facial paralysis; The use of the laser in head and neck surgery; The management and prevention of subglottic stenosis in infants and children; Management of the mass in the thyroid; Suction-assisted lipectomy of the head and neck area; and Ambulatory surgery.

  4. Rigid 3D-3D registration of TOF MRA integrating vessel segmentation for quantification of recurrence volumes after coiling cerebral aneurysm

    International Nuclear Information System (INIS)

    Saering, Dennis; Forkert, Nils Daniel; Fiehler, Jens; Ries, Thorsten

    2012-01-01

    A fast and reproducible quantification of the recurrence volume of coiled aneurysms is required to enable a more timely evaluation of new coils. This paper presents two registration schemes for the semi-automatic quantification of aneurysm recurrence volumes based on baseline and follow-up 3D MRA TOF datasets. The quantification of shape changes requires a previous definition of corresponding structures in both datasets. For this, two different rigid registration methods have been developed and evaluated. Besides a state-of-the-art rigid registration method, a second approach integrating vessel segmentations is presented. After registration, the aneurysm recurrence volume can be calculated based on the difference image. The computed volumes were compared to manually extracted volumes. An evaluation based on 20 TOF MRA datasets (baseline and follow-up) of ten patients showed that both registration schemes are generally capable of providing sufficient registration results. Regarding the quantification of aneurysm recurrence volumes, the results suggest that the second segmentation-based registration method yields better results, while a reduction of the computation and interaction time is achieved at the same time. The proposed registration scheme incorporating vessel segmentation enables an improved quantification of recurrence volumes of coiled aneurysms with reduced computation and interaction time. (orig.)

  5. Tokamak Physics EXperiment (TPX): Toroidal field magnet design, development and manufacture. SDRL 32, Coil assembly documentation. Volume 5

    International Nuclear Information System (INIS)

    Weber, C.M.

    1995-01-01

    This document is intended to address the contract requirement for providing coil assembly documentation, as required in the applicable Statement of Work: 'Provide preliminary procedures and preliminary design and supporting analysis of the equipment, fixtures, and hardware required to integrate and align the impregnated coil assemblies with the coil cases and intercoil structure. Each of the three major processes associated with the coil case and intercoil structure (ICS), TF Case Fabrication, Coil Preparation for Case Assembly are examined in detail. The specific requirements, processes, equipment, and technical concerns for each of these assembly processes is presented

  6. TFTR toroidal field coil design

    International Nuclear Information System (INIS)

    Smith, G.E.; Punchard, W.F.B.

    1977-01-01

    The design of the Tokamak Fusion Test Reactor (TFTR) Toroidal Field (TF) magnetic coils is described. The TF coil is a 44-turn, spiral-wound, two-pancake, water-cooled configuration which, at a coil current of 73.3 kiloamperes, produces a 5.2-Tesla field at a major radius of 2.48 meters. The magnetic coils are installed in titanium cases, which transmit the loads generated in the coils to the adjacent supporting structure. The TFTR utilizes 20 of these coils, positioned radially at 18 0 intervals, to provide the required toroidal field. Because it is very highly loaded and subject to tight volume constraints within the machine, the coil presents unique design problems. The TF coil requirements are summarized, the coil configuration is described, and the problems highlighted which have been encountered thus far in the coil design effort, together with the development tests which have been undertaken to verify the design

  7. Optimizing T2-weighted magnetic resonance sequences for surface coil microimaging of the eye with regard to lid, eyeball and head moving artifacts.

    Science.gov (United States)

    Obata, Takayuki; Uemura, Koji; Nonaka, Hiroi; Tamura, Mitsuru; Tanada, Shuji; Ikehira, Hiroo

    2006-01-01

    To acquire high-resolution magnetic resonance (MR) images, we developed a new blinking artifact reduced pulse (BARP) sequence with a surface coil specialized for microscopic imaging (47 mm in diameter). To reduce eye movement, we ascertained that the subjects' eyes were kept open and fixated to the target in the 1.5-T MR gantry. To reduce motion artifacts from blinking, we inserted rest periods for blinking (1.5 s within every 5 s) during MR scanning (T2-weighted fast spin echo; repetition time, 5 s; echo time, 100 ms; echo train, 11; matrix, 256 x 128; field of view, 5 cm; 1-mm thickness x 30 slices). Three scans (100 s x 3) were performed for each normal subject, and they were added together after automatic adjustment for location to reduce quality loss caused by head motion. T2-weighted MR images were acquired with a high resolution and a high signal-to-noise ratio. Motion artifacts were reduced with BARP, as compared with those with random blinking. Intraocular structures such as the iris and ciliary muscles were clearly visualized. Because the whole eye can be covered with a 1-mm thickness by this method, three-dimensional maps can easily be generated from the obtained images. The application of BARP with a surface coil of the human eye might become a useful and widely adopted procedure for MR microimaging.

  8. Measurement of creatine kinase reaction rate in human brain using magnetization transfer image-selected in vivo spectroscopy (MT-ISIS) and a volume ³¹P/¹H radiofrequency coil in a clinical 3-T MRI system.

    Science.gov (United States)

    Jeong, Eun-Kee; Sung, Young-Hoon; Kim, Seong-Eun; Zuo, Chun; Shi, Xianfeng; Mellon, Eric A; Renshaw, Perry F

    2011-08-01

    High-energy phosphate metabolism, which allows the synthesis and regeneration of adenosine triphosphate (ATP), is a vital process for neuronal survival and activity. In particular, creatine kinase (CK) serves as an energy reservoir for the rapid buffering of ATP levels. Altered CK enzyme activity, reflecting compromised high-energy phosphate metabolism or mitochondrial dysfunction in the brain, can be assessed using magnetization transfer (MT) MRS. MT (31)P MRS has been used to measure the forward CK reaction rate in animal and human brain, employing a surface radiofrequency coil. However, long acquisition times and excessive radiofrequency irradiation prevent these methods from being used routinely for clinical evaluations. In this article, a new MT (31)P MRS method is presented, which can be practically used to measure the CK forward reaction rate constant in a clinical MRI system employing a volume head (31)P coil for spatial localization, without contamination from the scalp muscle, and an acquisition time of 30 min. Other advantages associated with the method include radiofrequency homogeneity within the regions of interest of the brain using a volume coil with image-selected in vivo spectroscopy localization, and reduction of the specific absorption rate using nonadiabatic radiofrequency pulses for MT saturation. The mean value of k(f) was measured as 0.320 ± 0.075 s(-1) from 10 healthy volunteers with an age range of 18-40 years. These values are consistent with those obtained using earlier methods, and the technique may be used routinely to evaluate energetic processes in the brain on a clinical MRI system. Copyright © 2010 John Wiley & Sons, Ltd.

  9. Feasibility of a brain-dedicated PET-MRI system using four-layer DOI detectors integrated with an RF head coil

    International Nuclear Information System (INIS)

    Nishikido, F.; Obata, T.; Shimizu, K.; Suga, M.; Inadama, N.; Tachibana, A.; Yoshida, E.; Ito, H.; Yamaya, T.

    2014-01-01

    We are developing a PET-MRI system which consists of PET detectors integrated with the head coil of the MRI in order to realize high spatial resolution and high sensitivity in simultaneous measurements. In the PET-MRI system, the PET detectors which consist of a scintillator block, photo-detectors and front-end circuits with four-layer depth-of-interaction (DOI) encoding capability are placed close to the measured object. Therefore, the proposed system can achieve high sensitivity without degradation of spatial resolution at the edge of the field-of-view due to parallax error thanks to the four-layer DOI capability. In this paper, we fabricated a prototype system which consists of a prototype four-layer DOI-PET detector, a dummy PET detector and a prototype birdcage type head coil. Then we used the prototype system to evaluate the performance of the four-layer DOI-PET detector and the reciprocal influence between the PET detectors and MRI images. The prototype DOI-PET detector consists of six monolithic multi-pixel photon counter (MPPC) arrays (S11064-050P), a readout circuit board, two scintillator blocks and a copper shielding box. Each scintillator block consists of four layers of Lu 1.8 Gd 0.2 SiO 5 :Ce (LGSO) scintillators and reflectors are inserted between the scintillation crystals. The dummy detector has all these components except the two scintillator blocks. The head coil is dedicated to a 3.0 T MRI (MAGNETOM Verio, Siemens) and the two detectors are mounted in gaps between head coil elements. Energy resolution and crystal identification performance of the prototype four-layer DOI-PET detector were evaluated with and without MRI measurements by the gradient echo and spin echo methods. We identified crystal elements in all four layers from a 2D flood histogram and energy resolution of 15–18% was obtained for single crystal elements in simultaneous measurements. The difference between the average energy resolutions and photo-peak positions with and

  10. Electric field depth-focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs.

    Science.gov (United States)

    Deng, Zhi-De; Lisanby, Sarah H; Peterchev, Angel V

    2013-01-01

    Various transcranial magnetic stimulation (TMS) coil designs are available or have been proposed. However, key coil characteristics such as electric field focality and attenuation in depth have not been adequately compared. Knowledge of the coil focality and depth characteristics can help TMS researchers and clinicians with coil selection and interpretation of TMS studies. To quantify the electric field focality and depth of penetration of various TMS coils. The electric field distributions induced by 50 TMS coils were simulated in a spherical human head model using the finite element method. For each coil design, we quantified the electric field penetration by the half-value depth, d(1/2), and focality by the tangential spread, S(1/2), defined as the half-value volume (V(1/2)) divided by the half-value depth, S(1/2) = V(1/2)/d(1/2). The 50 TMS coils exhibit a wide range of electric field focality and depth, but all followed a depth-focality tradeoff: coils with larger half-value depth cannot be as focal as more superficial coils. The ranges of achievable d(1/2) are similar between coils producing circular and figure-8 electric field patterns, ranging 1.0-3.5 cm and 0.9-3.4 cm, respectively. However, figure-8 field coils are more focal, having S(1/2) as low as 5 cm(2) compared to 34 cm(2) for circular field coils. For any coil design, the ability to directly stimulate deeper brain structures is obtained at the expense of inducing wider electrical field spread. Novel coil designs should be benchmarked against comparison coils with consistent metrics such as d(1/2) and S(1/2). Copyright © 2013 Elsevier Inc. All rights reserved.

  11. System of coils for increasing the volume of homogeneous field between the parallel pole faces of an electromagnet

    International Nuclear Information System (INIS)

    Nelson, D.H.

    1975-01-01

    The design and evaluation of a system of coils for improving magnetic field homogeneity are discussed. Using only three coil-pairs the duration of NMR spin-echo signals from a sample of H 2 O (0.7 cm. diameter x 0.9 cm. long) was increased by an order of magnitude. (U.S.)

  12. Thermal and hydraulic analyses of TFTR cooling water system and magnetic field coils

    International Nuclear Information System (INIS)

    Lee, A.Y.

    1975-10-01

    The TFTR toroidal field coils, ohmic heating, hybrid and equilibrium field coils are cooled by water from the machine area cooling water system. The system has the following major equipment and capacities: flow rate of 3600 gpm; ballast tank volume of 5500 gal; pumps of 70.4 m head; chiller refrigeration rating of 3300 tons and connecting pipe of 45.7 cm I.D. The performance of the closed loop system was analyzed and found to be adequate for the thermal loads. The field coils were analyzed with detailed thermal and hydraulic models, including a simulation of the complete water cooling loop. Under the nominal operating mode of one second of toroidal field flat top time and 300 seconds of pulse cycle time, the maximum temperature for the TF coils is 53 0 C; for the OH coils 46 0 C and for the EF coils 39 0 C, which are well below the coil design limit of 120 0 C. The maximum TF coil coolant temperature is 33 0 C which is below the coolant design limit of 100 0 C. The overall pressure loss of the system is below 6.89 x 10 5 Pa (100 psi). With the given chiller refrigeration capacity, the TF coils can be operated to yield up to 4 seconds of flat top time. The TF coils can be operated on a steady state basis at up to 20% of the pulsed duty design current rating of 7.32 kA/coil

  13. Voice Coil Percussive Mechanism Concept for Hammer Drill

    Science.gov (United States)

    Okon, Avi

    2009-01-01

    A hammer drill design of a voice coil linear actuator, spring, linear bearings, and a hammer head was proposed. The voice coil actuator moves the hammer head to produce impact to the end of the drill bit. The spring is used to store energy on the retraction and to capture the rebound energy after each impact for use in the next impact. The maximum actuator stroke is 20 mm with the hammer mass being 200 grams. This unit can create impact energy of 0.4 J with 0.8 J being the maximum. This mechanism is less complex than previous devices meant for the same task, so it has less mass and less volume. Its impact rate and energy are easily tunable without changing major hardware components. The drill can be driven by two half-bridges. Heat is removed from the voice coil via CO2 conduction.

  14. Association between tumour volume and recurrence of squamous cell carcinoma of the head and neck

    International Nuclear Information System (INIS)

    Kazmi, F.N.; Adil, A.; Ghaffar, S.; Ahmed, F.

    2012-01-01

    Objective: To evaluate the prognostic significance of computerized tomography derived tumour volume for squamous cell cancers of the head and neck, treated primarily by surgery. Methods: The retrospective review study comprised 72 patients with head and neck malignancies who were treated primarily by surgery at Aga Khan University Hospital, Karachi, with/without adjuvant. It was done from May 2007 to November 2008. Each patient was followed up for a minimum of one year to check for recurrence. For statistical analysis SPSS 17 was used. Frequencies, cross-tabulations with chi square tests to find associations, binary logistic regression analysis, Cox regression analysis and receiver operating characteristic curve tests were run on the data. Results: Overall, the median tumour volume for patients with recurrent disease was 52 cm/sup 3/ compared to 22 cm/sup 3/ for those who did not have a recurrence. It was found that large tumour volume was associated with a significantly higher chance of recurrence (p = 0.009). Laryngeal cancers with volumes greater than 46 cm/sup 3/ and oral cancers with volumes greater than 23.1 cm/sup 3/ were associated with poor prognosis. Conclusions: The primary tumour volume can represent an important prognostic factor for treatment outcome. Patients with larger primary tumour volumes should be treated more aggressively. (author)

  15. Optimization of Coil Element Configurations for a Matrix Gradient Coil.

    Science.gov (United States)

    Kroboth, Stefan; Layton, Kelvin J; Jia, Feng; Littin, Sebastian; Yu, Huijun; Hennig, Jurgen; Zaitsev, Maxim

    2018-01-01

    Recently, matrix gradient coils (also termed multi-coils or multi-coil arrays) were introduced for imaging and B 0 shimming with 24, 48, and even 84 coil elements. However, in imaging applications, providing one amplifier per coil element is not always feasible due to high cost and technical complexity. In this simulation study, we show that an 84-channel matrix gradient coil (head insert for brain imaging) is able to create a wide variety of field shapes even if the number of amplifiers is reduced. An optimization algorithm was implemented that obtains groups of coil elements, such that a desired target field can be created by driving each group with an amplifier. This limits the number of amplifiers to the number of coil element groups. Simulated annealing is used due to the NP-hard combinatorial nature of the given problem. A spherical harmonic basis set up to the full third order within a sphere of 20-cm diameter in the center of the coil was investigated as target fields. We show that the median normalized least squares error for all target fields is below approximately 5% for 12 or more amplifiers. At the same time, the dissipated power stays within reasonable limits. With a relatively small set of amplifiers, switches can be used to sequentially generate spherical harmonics up to third order. The costs associated with a matrix gradient coil can be lowered, which increases the practical utility of matrix gradient coils.

  16. MR angiography of the carotid arteries in 3 D TOF-technique with sagittal ''double-slab'' acquisition using a new head-neck coil

    International Nuclear Information System (INIS)

    Link, J.; Mueller-Huelsbeck, S.; Heller, M.

    1996-01-01

    Purpose: The aim of the study was to assess the value of MR angiography (MRA) in sagittal technique compared to DSA in the evaluation of carotid artery stenosis. Methods: 80 Carotid arteries in 40 symptomatic patients were prospectively studied with DSA and MRA. MRA was carried out by means of 3D time-of-flight technique with a FISP sequence (T E 6 ms/T R 80 ms, flip angle 25 , FOV 240x210 mm, matrix 157x256 mm, in-plane resolution 1.34x0.94 mm, partition thickness 1.32 mm, slab thickness 45 mm, acquisition time 7 min) using a new head-neck coil. Data acquisition was performed in sagittal orientation with the 'double-slab' technique. Imaging quality of the extracranial carotid arteries and correctness of quantification of stenosis was performed. Results: Imaging quality was good at the origin of the carotid arteries in 65%, at the bifurcation region in 98% and near the skull base in 81%. The agreement of DSA and MRA was 96% of the normal arteries (24/25), 90% of the severe stenoses (28/31) and 100% of the occluded arteries (9/9). Conclusion: MRA in sagittal 'double-slab' technique is a noninvasive technique allowing to detect normal arteries and candidates for surgery with high degree of certainity. (orig.) [de

  17. Improving the spatial accuracy in functional magnetic resonance imaging (fMRI) based on the blood oxygenation level dependent (BOLD) effect: benefits from parallel imaging and a 32-channel head array coil at 1.5 Tesla.

    Science.gov (United States)

    Fellner, C; Doenitz, C; Finkenzeller, T; Jung, E M; Rennert, J; Schlaier, J

    2009-01-01

    Geometric distortions and low spatial resolution are current limitations in functional magnetic resonance imaging (fMRI). The aim of this study was to evaluate if application of parallel imaging or significant reduction of voxel size in combination with a new 32-channel head array coil can reduce those drawbacks at 1.5 T for a simple hand motor task. Therefore, maximum t-values (tmax) in different regions of activation, time-dependent signal-to-noise ratios (SNR(t)) as well as distortions within the precentral gyrus were evaluated. Comparing fMRI with and without parallel imaging in 17 healthy subjects revealed significantly reduced geometric distortions in anterior-posterior direction. Using parallel imaging, tmax only showed a mild reduction (7-11%) although SNR(t) was significantly diminished (25%). In 7 healthy subjects high-resolution (2 x 2 x 2 mm3) fMRI was compared with standard fMRI (3 x 3 x 3 mm3) in a 32-channel coil and with high-resolution fMRI in a 12-channel coil. The new coil yielded a clear improvement for tmax (21-32%) and SNR(t) (51%) in comparison with the 12-channel coil. Geometric distortions were smaller due to the smaller voxel size. Therefore, the reduction in tmax (8-16%) and SNR(t) (52%) in the high-resolution experiment seems to be tolerable with this coil. In conclusion, parallel imaging is an alternative to reduce geometric distortions in fMRI at 1.5 T. Using a 32-channel coil, reduction of the voxel size might be the preferable way to improve spatial accuracy.

  18. A primitive study on unsupervised anomaly detection with an autoencoder in emergency head CT volumes

    Science.gov (United States)

    Sato, Daisuke; Hanaoka, Shouhei; Nomura, Yukihiro; Takenaga, Tomomi; Miki, Soichiro; Yoshikawa, Takeharu; Hayashi, Naoto; Abe, Osamu

    2018-02-01

    Purpose: The target disorders of emergency head CT are wide-ranging. Therefore, people working in an emergency department desire a computer-aided detection system for general disorders. In this study, we proposed an unsupervised anomaly detection method in emergency head CT using an autoencoder and evaluated the anomaly detection performance of our method in emergency head CT. Methods: We used a 3D convolutional autoencoder (3D-CAE), which contains 11 layers in the convolution block and 6 layers in the deconvolution block. In the training phase, we trained the 3D-CAE using 10,000 3D patches extracted from 50 normal cases. In the test phase, we calculated abnormalities of each voxel in 38 emergency head CT volumes (22 abnormal cases and 16 normal cases) for evaluation and evaluated the likelihood of lesion existence. Results: Our method achieved a sensitivity of 68% and a specificity of 88%, with an area under the curve of the receiver operating characteristic curve of 0.87. It shows that this method has a moderate accuracy to distinguish normal CT cases to abnormal ones. Conclusion: Our method has potentialities for anomaly detection in emergency head CT.

  19. Three-dimensional US assessment of hepatic volume, head circumference, and abdominal circumference in healthy and growth-restricted fetuses

    NARCIS (Netherlands)

    S.M. Boito; J.A.M. Laudij (Jacqueline); P.C. Struijk (Pieter); Th. Stijnen (Theo); J.W. Wladimiroff (Juriy)

    2002-01-01

    textabstractPURPOSE: To establish reproducibility and normal values for fetal hepatic volume and its significance in identification of fetal growth restriction relative to head and upper abdominal circumferences according to a cross-sectional study design. MATERIALS AND METHODS:

  20. Evaluation of PET/MRI for Tumor Volume Delineation for Head and Neck Cancer.

    Science.gov (United States)

    Wang, Kyle; Mullins, Brandon T; Falchook, Aaron D; Lian, Jun; He, Kelei; Shen, Dinggang; Dance, Michael; Lin, Weili; Sills, Tiffany M; Das, Shiva K; Huang, Benjamin Y; Chera, Bhishamjit S

    2017-01-01

    Computed tomography (CT), combined positron emitted tomography and CT (PET/CT), and magnetic resonance imaging (MRI) are commonly used in head and neck radiation planning. Hybrid PET/MRI has garnered attention for potential added value in cancer staging and treatment planning. Herein, we compare PET/MRI vs. planning CT for head and neck cancer gross tumor volume (GTV) delineation. We prospectively enrolled patients with head and neck cancer treated with definitive chemoradiation to 60-70 Gy using IMRT. We performed pretreatment contrast-enhanced planning CT and gadolinium-enhanced PET/MRI. Primary and nodal volumes were delineated on planning CT (GTV-CT) prospectively before treatment and PET/MRI (GTV-PET/MRI) retrospectively after treatment. GTV-PET/MRI was compared to GTV-CT using separate rigid registrations for each tumor volume. The Dice similarity coefficient (DSC) metric evaluating spatial overlap and modified Hausdorff distance (mHD) evaluating mean orthogonal distance difference were calculated. Minimum dose to 95% of GTVs (D95) was compared. Eleven patients were evaluable (10 oropharynx, 1 larynx). Nine patients had evaluable primary tumor GTVs and seven patients had evaluable nodal GTVs. Mean primary GTV-CT and GTV-PET/MRI size were 13.2 and 14.3 cc, with mean intersection 8.7 cc, DSC 0.63, and mHD 1.6 mm. D95 was 65.3 Gy for primary GTV-CT vs. 65.2 Gy for primary GTV-PET/MRI. Mean nodal GTV-CT and GTV-PET/MRI size were 19.0 and 23.0 cc, with mean intersection 14.4 cc, DSC 0.69, and mHD 2.3 mm. D95 was 62.3 Gy for both nodal GTV-CT and GTV-PET/MRI. In this series of patients with head and neck (primarily oropharynx) cancer, PET/MRI and CT-GTVs had similar volumes (though there were individual cases with larger differences) with overall small discrepancies in spatial overlap, small mean orthogonal distance differences, and similar radiation doses.

  1. Triple Halo Coil: Development and Comparison with Other TMS Coils

    Science.gov (United States)

    Rastogi, Priyam; Hadimani, Ravi; Jiles, David

    Transcranial Magnetic Stimulation (TMS) is a non-invasive stimulation technique that can be used for the treatment of various neurological disorders such as Parkinson's Disease, PTSD, TBI and anxiety by regulating synaptic activity. TMS is FDA approved for the treatment of major depressive disorder. There is a critical need to develop deep TMS coils that can stimulate deeper regions of the brain without excessively stimulating the cortex in order to provide an alternative to surgical methods. We have developed a novel multi-coil configuration called ``Triple Halo Coil'' (THC) that can stimulate deep brain regions. Investigation of induced electric and magnetic field in these regions have been achieved by computer modelling. Comparison of the results due to THC configuration have been conducted with other TMS coils such as ``Halo Coil'', circular coil and ``Figure of Eight'' coil. There was an improvement of more than 15 times in the strength of magnetic field, induced by THC configuration at 10 cm below the vertex of the head when compared with the ``Figure of Eight'' coil alone. Carver Charitable Trust.

  2. Assessment of the characteristics of MRI coils in terms of RF non-homogeneity using routine spin echo sequences

    International Nuclear Information System (INIS)

    Oghabian, M. A.; Mehdipour, Sh.; RiahicAlam, N.; Rafie, B.; Ghanaati, H.

    2005-01-01

    One of the major causes of image non-uniformity in MRI is due to the existence of non-homogeneity in RF receive and transmit. This can be the most effective source of error in quantitative studies in MRI imaging. Part of this non-homogeneity demonstrates the characteristics of RF coil and part of it is due to the interaction of RF field with the material being imaged. In this study, RF field non-homogeneity of surface and volume coils is measured using an oil phantom. The method employed in this work is based on a routine Spin Echo based sequence as proposed by this group previously. Materials and Methods: For the determination of RF non-uniformity, a method based on Spin Echo sequence (8θ-180) was used as reported previously by the same author. In this method, several images were obtained from one slice using different flip angles while keeping all other imaging parameters constant. Then, signal intensity at a ROI from all of these images were measured and fitted to the MRI defined mathematical model. Since this mathematical model describes the relation between signal intensity and flip angle in a (8θ-180) Spin Echo sequence, it is possible to obtain the variation in receive and transmit sensitivity in terms of the variation of signal intensity from the actual expected values. Since surface coils are functioning as only receiver (RF transmission is done by Body coil), first the results of receive coil homogeneity is measured, then characteristic of transmit coil (for the body coil) is evaluated Results: The coefficient of variation (C.V.) found for T(r) value obtained from images using head coils was in the order of 0.6%. Since the head coil is functioning as both transmitter and receiver, any non-uniformity in either transmit or receive stage can lead to non-homogeneity in RF field. A part from the surface coils, the amount of non-homogeneity due to receive coil was less than that of the transmit coil. In the case of the surface coils the variation in receive

  3. Segmentation of organs at risk in CT volumes of head, thorax, abdomen, and pelvis

    Science.gov (United States)

    Han, Miaofei; Ma, Jinfeng; Li, Yan; Li, Meiling; Song, Yanli; Li, Qiang

    2015-03-01

    Accurate segmentation of organs at risk (OARs) is a key step in treatment planning system (TPS) of image guided radiation therapy. We are developing three classes of methods to segment 17 organs at risk throughout the whole body, including brain, brain stem, eyes, mandible, temporomandibular joints, parotid glands, spinal cord, lungs, trachea, heart, livers, kidneys, spleen, prostate, rectum, femoral heads, and skin. The three classes of segmentation methods include (1) threshold-based methods for organs of large contrast with adjacent structures such as lungs, trachea, and skin; (2) context-driven Generalized Hough Transform-based methods combined with graph cut algorithm for robust localization and segmentation of liver, kidneys and spleen; and (3) atlas and registration-based methods for segmentation of heart and all organs in CT volumes of head and pelvis. The segmentation accuracy for the seventeen organs was subjectively evaluated by two medical experts in three levels of score: 0, poor (unusable in clinical practice); 1, acceptable (minor revision needed); and 2, good (nearly no revision needed). A database was collected from Ruijin Hospital, Huashan Hospital, and Xuhui Central Hospital in Shanghai, China, including 127 head scans, 203 thoracic scans, 154 abdominal scans, and 73 pelvic scans. The percentages of "good" segmentation results were 97.6%, 92.9%, 81.1%, 87.4%, 85.0%, 78.7%, 94.1%, 91.1%, 81.3%, 86.7%, 82.5%, 86.4%, 79.9%, 72.6%, 68.5%, 93.2%, 96.9% for brain, brain stem, eyes, mandible, temporomandibular joints, parotid glands, spinal cord, lungs, trachea, heart, livers, kidneys, spleen, prostate, rectum, femoral heads, and skin, respectively. Various organs at risk can be reliably segmented from CT scans by use of the three classes of segmentation methods.

  4. Design of a dynamic transcranial magnetic stimulation coil system.

    Science.gov (United States)

    Ge, Sheng; Jiang, Ruoli; Wang, Ruimin; Chen, Ji

    2014-08-01

    To study the brain activity at the whole-head range, transcranial magnetic stimulation (TMS) researchers need to investigate brain activity over the whole head at multiple locations. In the past, this has been accomplished with multiple single TMS coils that achieve quasi whole-head array stimulation. However, these designs have low resolution and are difficult to position and control over the skull. In this study, we propose a new dynamic whole-head TMS mesh coil system. This system was constructed using several sagittal and coronal directional wires. Using both simulation and real experimental data, we show that by varying the current direction and strength of each wire, this new coil system can form both circular coils or figure-eight coils that have the same features as traditional TMS coils. Further, our new system is superior to current coil systems because stimulation parameters such as size, type, location, and timing of stimulation can be dynamically controlled within a single experiment.

  5. Pulmonary Perfusion Changes as Assessed by Contrast-Enhanced Dual-Energy Computed Tomography after Endoscopic Lung Volume Reduction by Coils.

    Science.gov (United States)

    Lador, Frédéric; Hachulla, Anne-Lise; Hohn, Olivia; Plojoux, Jérôme; Ronot, Maxime; Montet, Xavier; Soccal, Paola M

    2016-01-01

    Endoscopic lung volume reduction by coils (LVRC) is a recent treatment approach for severe emphysema. Furthermore, dual-energy computed tomography (DECT) now offers a combined assessment of lung morphology and pulmonary perfusion. The aim of our study was to assess the impact of LVRC on pulmonary perfusion with DECT. Seventeen patients (64.8 ± 6.7 years) underwent LVRC. DECT was performed prior to and after LVRC. For each patient, lung volumes and emphysema quantification were automatically calculated. Then, 6 regions of interest (ROIs) on the iodine perfusion map were drawn in the anterior, mid, and posterior right and left lungs at 4 defined levels. The ROI values were averaged to obtain lung perfusion as assessed by the lung's iodine concentration (CLung, μg·cm-3). The CLung values were normalized using the left atrial iodine concentration (CLA) to take into account differences between successive DECT scans. The 6-min walk distance (6MWD) improved significantly after the procedure (p = 0.0002). No lung volume changes were observed between successive DECT scans for any of the patients (p = 0.32), attesting the same suspended inspiration. After LVRC, the emphysema index was significantly reduced in the treated lung (p = 0.0014). Lung perfusion increased significantly adjacent to the treated areas (CLung/CLA from 3.4 ± 1.7 to 5.6 ± 2.2, p < 0.001) and in the ipsilateral untreated areas (from 4.1 ± 1.4 to 6.6 ± 1.7, p < 0.001), corresponding to a mean 65 and 61% increase in perfusion, respectively. No significant difference was observed in the contralateral upper and lower areas (from 4.4 ± 1.9 to 4.8 ± 2.1, p = 0.273, and from 4.9 ± 2.0 to 5.2 ± 1.7, p = 0.412, respectively). A significant correlation between increased 6MWD and increased perfusion was found (p = 0.0027, R2 = 0.3850). Quantitative analysis based on DECT acquisition revealed that LVRC results in a significant increase in perfusion in the coil-free areas adjacent to the treated ones, as

  6. Heteronuclear Micro-Helmholtz Coil Facilitates µm-Range Spatial and Sub-Hz Spectral Resolution NMR of nL-Volume Samples on Customisable Microfluidic Chips.

    Directory of Open Access Journals (Sweden)

    Nils Spengler

    Full Text Available We present a completely revised generation of a modular micro-NMR detector, featuring an active sample volume of ∼ 100 nL, and an improvement of 87% in probe efficiency. The detector is capable of rapidly screening different samples using exchangeable, application-specific, MEMS-fabricated, microfluidic sample containers. In contrast to our previous design, the sample holder chips can be simply sealed with adhesive tape, with excellent adhesion due to the smooth surfaces surrounding the fluidic ports, and so withstand pressures of ∼2.5 bar, while simultaneously enabling high spectral resolution up to 0.62 Hz for H2O, due to its optimised geometry. We have additionally reworked the coil design and fabrication processes, replacing liquid photoresists by dry film stock, whose final thickness does not depend on accurate volume dispensing or precise levelling during curing. We further introduced mechanical alignment structures to avoid time-intensive optical alignment of the chip stacks during assembly, while we exchanged the laser-cut, PMMA spacers by diced glass spacers, which are not susceptible to melting during cutting. Doing so led to an overall simplification of the entire fabrication chain, while simultaneously increasing the yield, due to an improved uniformity of thickness of the individual layers, and in addition, due to more accurate vertical positioning of the wirebonded coils, now delimited by a post base plateau. We demonstrate the capability of the design by acquiring a 1H spectrum of ∼ 11 nmol sucrose dissolved in D2O, where we achieved a linewidth of 1.25 Hz for the TSP reference peak. Chemical shift imaging experiments were further recorded from voxel volumes of only ∼ 1.5 nL, which corresponded to amounts of just 1.5 nmol per voxel for a 1 M concentration. To extend the micro-detector to other nuclei of interest, we have implemented a trap circuit, enabling heteronuclear spectroscopy, demonstrated by two 1H/13C 2D HSQC

  7. The value of magnetic resonance imaging in target volume delineation of base of tongue tumours - A study using flexible surface coils

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Merina [Department of Radiotherapy, Royal Marsden NHS Foundation Trust, London (United Kingdom); Schmidt, Maria [Cancer Research UK Clinical Magnetic Resonance Group, Royal Marsden NHS Foundation Trust, Surrey (United Kingdom); Sohaib, Aslam [Department of Radiology, Royal Marsden NHS Foundation Trust, London (United Kingdom); Kong, Christine; Burke, Kevin [Department of Radiotherapy, Royal Marsden NHS Foundation Trust, London (United Kingdom); Richardson, Cheryl; Usher, Marianne [Cancer Research UK Clinical Magnetic Resonance Group, Royal Marsden NHS Foundation Trust, Surrey (United Kingdom); Brennan, Sinead [Department of Radiotherapy, St. James' s Hospital, Dublin (Ireland); Riddell, Angela [Department of Radiology, Royal Marsden NHS Foundation Trust, London (United Kingdom); Davies, Mark; Newbold, Kate [Department of Radiotherapy, Royal Marsden NHS Foundation Trust, London (United Kingdom); Harrington, Kevin J; Nutting, Christopher M [Department of Radiotherapy, Royal Marsden NHS Foundation Trust, London (United Kingdom); Institute of Cancer Research, London (United Kingdom)

    2010-02-15

    Introduction: Magnetic resonance imaging (MRI) provides superior diagnostic accuracy over computed tomography (CT) in oropharyngeal tumours. Precise delineation of the gross tumour volume (GTV) is mandatory in radiotherapy planning when a GTV boost is required. CT volume definition in this regard is poor. We studied the feasibility of using flexible surface (flex-L) coils to obtain MR images for MR-CT fusion to assess the benefit of MRI over CT alone in planning base of tongue tumours. Methods: Eight patients underwent CT and MRI radiotherapy planning scans with an immobilisation device. Distortion-corrected T1-weighted post-contrast MR scans were fused to contrast-enhanced planning CT scans. GTV, clinical target and planning target volumes (CTV, PTV) and organs at risk (OAR) were delineated on CT, then on MRI with blinding to the CT images. The volumetric and spatial differences between MRI and CT volumes for GTV, CTV, PTV and OAR were compared. MR image distortions due to field inhomogeneity and non-linear gradients were corrected and the need for such correction was evaluated. Results: The mean primary GTV was larger on MRI (22.2 vs. 9.5 cm{sup 3}, p = 0.05) than CT. The mean primary and nodal GTV (i.e. BOT and macroscopic nodes) was significantly larger on MRI (27.2 vs. 14.4 cm{sup 3}, p = 0.05). The volume overlap index (VOI) between MRI and CT for the primary was 0.34 suggesting that MRI depicts parts of the primary tumour not detected by CT. There was no significant difference in volume delineation between MR and CT for CTV, PTV, nodal CTV and nodal PTV. MRI volumes for brainstem and spinal cord were significantly smaller due to improved organ definition (p = 0.002). Susceptibility and gradient-related distortions were not found to be clinically significant. Conclusion: MRI improves the definition of tongue base tumours and neurological structures. The use of MRI is recommended for GTV dose-escalation techniques to provide precise depiction of GTV and

  8. The value of magnetic resonance imaging in target volume delineation of base of tongue tumours - A study using flexible surface coils

    International Nuclear Information System (INIS)

    Ahmed, Merina; Schmidt, Maria; Sohaib, Aslam; Kong, Christine; Burke, Kevin; Richardson, Cheryl; Usher, Marianne; Brennan, Sinead; Riddell, Angela; Davies, Mark; Newbold, Kate; Harrington, Kevin J.; Nutting, Christopher M.

    2010-01-01

    Introduction: Magnetic resonance imaging (MRI) provides superior diagnostic accuracy over computed tomography (CT) in oropharyngeal tumours. Precise delineation of the gross tumour volume (GTV) is mandatory in radiotherapy planning when a GTV boost is required. CT volume definition in this regard is poor. We studied the feasibility of using flexible surface (flex-L) coils to obtain MR images for MR-CT fusion to assess the benefit of MRI over CT alone in planning base of tongue tumours. Methods: Eight patients underwent CT and MRI radiotherapy planning scans with an immobilisation device. Distortion-corrected T1-weighted post-contrast MR scans were fused to contrast-enhanced planning CT scans. GTV, clinical target and planning target volumes (CTV, PTV) and organs at risk (OAR) were delineated on CT, then on MRI with blinding to the CT images. The volumetric and spatial differences between MRI and CT volumes for GTV, CTV, PTV and OAR were compared. MR image distortions due to field inhomogeneity and non-linear gradients were corrected and the need for such correction was evaluated. Results: The mean primary GTV was larger on MRI (22.2 vs. 9.5 cm 3 , p = 0.05) than CT. The mean primary and nodal GTV (i.e. BOT and macroscopic nodes) was significantly larger on MRI (27.2 vs. 14.4 cm 3 , p = 0.05). The volume overlap index (VOI) between MRI and CT for the primary was 0.34 suggesting that MRI depicts parts of the primary tumour not detected by CT. There was no significant difference in volume delineation between MR and CT for CTV, PTV, nodal CTV and nodal PTV. MRI volumes for brainstem and spinal cord were significantly smaller due to improved organ definition (p = 0.002). Susceptibility and gradient-related distortions were not found to be clinically significant. Conclusion: MRI improves the definition of tongue base tumours and neurological structures. The use of MRI is recommended for GTV dose-escalation techniques to provide precise depiction of GTV and improved

  9. Late dysphagia after IMRT for head and neck cancer and correlation with dose–volume parameters

    International Nuclear Information System (INIS)

    Mortensen, Hanna R.; Jensen, Kenneth; Aksglæde, Karin; Behrens, Marie; Grau, Cai

    2013-01-01

    Background and purpose: Many head and neck cancer (HNC) survivors experience diminished quality of life due to radiation-induced dysphagia. The aim of this study was to investigate frequency, intensity and dose–volume dependency for late dysphagia in HNC patients treated with curative IMRT. Materials and methods: Candidates for the study were 294 patients treated with primary IMRT from 2006 to 2010; a total of 259 patients accepted to participate by answering the EORTC QLQ-C30 and H and N35 questionnaires. A total of 65 patients were further examined with modified barium swallow (MBS) and saliva collection. Data on patient, tumor and treatment characteristics were prospectively recorded in the DAHANCA database. Dose–volume histograms (DVH) of swallowing-related structures were retrospectively analyzed. Results: QoL data showed low degree of dysphagia (QoL subscales scores of 17 and below) compared to objective measures. The most frequent swallowing dysfunction was retention; penetration and aspiration was less common. In general, objective measurements and observer-assessed late dysphagia correlated with dose to pharyngeal constrictor muscles (PCM), whereas QoL endpoints correlated with DVH parameters in the glottis/supraglottic larynx. Both xerostomia and dysphagia has been reduced after introduction of IMRT. Conclusions: Radiation-induced dysphagia is still important, with a high degree of retention and penetration. Introduction of parotid-sparing IMRT has reduced the severity of dysphagia, primarily through a major reduction in xerostomia. Dose–response relationships were found for specific dysphagia endpoints

  10. Investigation of tDCS volume conduction effects in a highly realistic head model

    Science.gov (United States)

    Wagner, S.; Rampersad, S. M.; Aydin, Ü.; Vorwerk, J.; Oostendorp, T. F.; Neuling, T.; Herrmann, C. S.; Stegeman, D. F.; Wolters, C. H.

    2014-02-01

    Objective. We investigate volume conduction effects in transcranial direct current stimulation (tDCS) and present a guideline for efficient and yet accurate volume conductor modeling in tDCS using our newly-developed finite element (FE) approach. Approach. We developed a new, accurate and fast isoparametric FE approach for high-resolution geometry-adapted hexahedral meshes and tissue anisotropy. To attain a deeper insight into tDCS, we performed computer simulations, starting with a homogenized three-compartment head model and extending this step by step to a six-compartment anisotropic model. Main results. We are able to demonstrate important tDCS effects. First, we find channeling effects of the skin, the skull spongiosa and the cerebrospinal fluid compartments. Second, current vectors tend to be oriented towards the closest higher conducting region. Third, anisotropic WM conductivity causes current flow in directions more parallel to the WM fiber tracts. Fourth, the highest cortical current magnitudes are not only found close to the stimulation sites. Fifth, the median brain current density decreases with increasing distance from the electrodes. Significance. Our results allow us to formulate a guideline for volume conductor modeling in tDCS. We recommend to accurately model the major tissues between the stimulating electrodes and the target areas, while for efficient yet accurate modeling, an exact representation of other tissues is less important. Because for the low-frequency regime in electrophysiology the quasi-static approach is justified, our results should also be valid for at least low-frequency (e.g., below 100 Hz) transcranial alternating current stimulation.

  11. Radial displacement of clinical target volume in node negative head and neck cancer

    International Nuclear Information System (INIS)

    Jeon, Wan; Wu, Hong Gyun; Song, Sang Hyuk; Kim, Jung In

    2012-01-01

    To evaluate the radial displacement of clinical target volume in the patients with node negative head and neck (H and N) cancer and to quantify the relative positional changes compared to that of normal healthy volunteers. Three node-negative H and N cancer patients and fi ve healthy volunteers were enrolled in this study. For setup accuracy, neck thermoplastic masks and laser alignment were used in each of the acquired computed tomography (CT) images. Both groups had total three sequential CT images in every two weeks. The lymph node (LN) level of the neck was delineated based on the Radiation Therapy Oncology Group (RTOG) consensus guideline by one physician. We use the second cervical vertebra body as a reference point to match each CT image set. Each of the sequential CT images and delineated neck LN levels were fused with the primary image, then maximal radial displacement was measured at 1.5 cm intervals from skull base (SB) to caudal margin of LN level V, and the volume differences at each node level were quantified. The mean radial displacements were 2.26 (±1.03) mm in the control group and 3.05 (±1.97) in the H and N cancer patients. There was a statistically significant difference between the groups in terms of the mean radial displacement (p = 0.03). In addition, the mean radial displacement increased with the distance from SB. As for the mean volume differences, there was no statistical significance between the two groups. This study suggests that a more generous radial margin should be applied to the lower part of the neck LN for better clinical target coverage and dose delivery.

  12. Can FDG-PET assist in radiotherapy target volume definition of metastatic lymph nodes in head-and-neck cancer?

    NARCIS (Netherlands)

    Schinagl, D.A.X.; Hoffmann, A.L.; Vogel, W.V.; Dalen, J.A. van; Verstappen, S.M.M.; Oyen, W.J.G.; Kaanders, J.H.A.M.

    2009-01-01

    BACKGROUND AND PURPOSE: The role of FDG-PET in radiotherapy target volume definition of the neck was evaluated by comparing eight methods of FDG-PET segmentation to the current CT-based practice of lymph node assessment in head-and-neck cancer patients. MATERIALS AND METHODS: Seventy-eight

  13. Tumor response parameters for head and neck cancer derived from tumor-volume variation during radiation therapy

    International Nuclear Information System (INIS)

    Chvetsov, Alexei V.

    2013-01-01

    Purpose: The main goal of this paper is to reconstruct a distribution of cell survival fractions from tumor-volume variation for a heterogeneous group of head and neck cancer patients and compare this distribution to the data from predictive assays. Methods: To characterize the tumor-volume variation during radiation therapy treatment, the authors use a two-level tumor-volume model of cell population that separates the entire tumor cell population into two subpopulations of viable cells and lethally damaged cells. This parameterized radiobiological model is integrated with a least squares objective function and a simulated annealing optimization algorithm to describe time-dependent tumor-volume variation rates in individual patients. Several constraints have been used in the optimization problem because tumor-volume variation during radiotherapy is described by a sum of exponentials; therefore, the problem of accurately fitting a model to measured data is ill-posed. The model was applied to measured tumor-volume variation curves from a clinical study on tumor-volume variation during radiotherapy for 14 head and neck cancer patients in which an integrated CT/linear particle accelerator (LINAC) system was used for tumor-volume measurements. Results: The two-level cell population tumor-volume modeling is capable of describing tumor-volume variation throughout the entire treatment for 11 of the 14 patients. For three patients, the tumor-volume variation was described only during the initial part of treatment, a fact that may be related to the neglected hypoxia in the two-level approximation. The predicted probability density distribution for the survival fractions agrees with the data obtained using in vitro studies with predictive assays. The mean value 0.35 of survival fraction obtained in this study is larger than the value 0.32 from in vitro studies, which could be expected because of greater repair in vivo. The mean half-life obtained in this study for the head

  14. Room Volume Estimation Based on Ambiguity of Short-Term Interaural Phase Differences Using Humanoid Robot Head

    Directory of Open Access Journals (Sweden)

    Ryuichi Shimoyama

    2016-07-01

    Full Text Available Humans can recognize approximate room size using only binaural audition. However, sound reverberation is not negligible in most environments. The reverberation causes temporal fluctuations in the short-term interaural phase differences (IPDs of sound pressure. This study proposes a novel method for a binaural humanoid robot head to estimate room volume. The method is based on the statistical properties of the short-term IPDs of sound pressure. The humanoid robot turns its head toward a sound source, recognizes the sound source, and then estimates the ego-centric distance by its stereovision. By interpolating the relations between room volume, average standard deviation, and ego-centric distance experimentally obtained for various rooms in a prepared database, the room volume was estimated by the binaural audition of the robot from the average standard deviation of the short-term IPDs at the estimated distance.

  15. Dose assessment of head CT examination by volume scanning with 320-area-detector

    International Nuclear Information System (INIS)

    Suzuki, Shoichi; Kobayashi, Masanao

    2009-01-01

    CT with the 320-area-detector (320-ADCT), first presented in 2007, still requires further basic studies, particularly in the field of dose assessment, as the CT has been widely spread in clinic due to its many advantages compared with the usual spiral CT. In this paper, the assessment in the title was thereby done in human phantom and a patient with suspicious acute cerebral infarction under different scanning modes (non-spiral, spiral and volume) for their comparison. Machines for 320-ADCT, and non-spiral and spiral CT were Toshiba Aquilion ONE, and Aquilion 64-MD, respectively. Scanning of the phantom and patient was individually conducted under similar conditions of tube voltage/ current, rotation time and length with the same field of view with defined nominal slice thicknesses. Alderson human body phantom in which 240 thermoluminescent dosimeters were indwelled, was used; doses were read by the thermoluminescence dosimeter (TLD) reader model 3000 (Kyokko Co.) after scanning; and effective doses were calculated with reference to ICRP publ. 102/103 equations for patient's head to be 4.2 (64-MDCT) and 6.6 (320-ADCT) mSv, which were respectively 6.4 and 5.4 mSv when estimated using the conversion coefficient and DLP (dose length product) in the texts. It was suggested that the exposure dose at the volume scanning by 320-ADCT can be reduced in the routine examination, and in the exact diagnosis, possibly increases. These doses can be reduced further by optimization of scanning conditions by additional basic investigations. (K.T.)

  16. Institutional clinical trial accrual volume and survival of patients with head and neck cancer.

    Science.gov (United States)

    Wuthrick, Evan J; Zhang, Qiang; Machtay, Mitchell; Rosenthal, David I; Nguyen-Tan, Phuc Felix; Fortin, André; Silverman, Craig L; Raben, Adam; Kim, Harold E; Horwitz, Eric M; Read, Nancy E; Harris, Jonathan; Wu, Qian; Le, Quynh-Thu; Gillison, Maura L

    2015-01-10

    National Comprehensive Cancer Network guidelines recommend patients with head and neck cancer (HNC) receive treatment at centers with expertise, but whether provider experience affects survival is unknown. The effect of institutional experience on overall survival (OS) in patients with stage III or IV HNC was investigated within a randomized trial of the Radiation Therapy Oncology Group (RTOG 0129), which compared cisplatin concurrent with standard versus accelerated fractionation radiotherapy. As a surrogate for experience, institutions were classified as historically low- (HLACs) or high-accruing centers (HHACs) based on accrual to 21 RTOG HNC trials (1997 to 2002). The effect of accrual volume on OS was estimated by Cox proportional hazards models. Median RTOG accrual (1997 to 2002) at HLACs was four versus 65 patients at HHACs. Analysis included 471 patients in RTOG 0129 (2002 to 2005) with known human papillomavirus and smoking status. Patients at HLACs versus HHACs had better performance status (0: 62% v 52%; P = .04) and lower T stage (T4: 26.5% v 35.3%; P = .002) but were otherwise similar. Radiotherapy protocol deviations were higher at HLACs versus HHACs (18% v 6%; P accounting for radiotherapy protocol deviations. Institutional experience substantially influences survival in locally advanced HNC. © 2014 by American Society of Clinical Oncology.

  17. Improvement of Head-Up Display Standards. Volume 5. Head Up Display ILS (Instrument Landing System) Accuracy Flight Tests.

    Science.gov (United States)

    1987-09-01

    amber system. The front canopy of the NT-33A is cov- ered with an amber plastic sheet; when the front seat pilot low- ers his blue visor, the...tigation of the effect of head-up display symbol dynamic response caracteristics on flying qualities; Task B was an investigation of symbol accuracy...An amber vinyl plastic sheet covered the in- side front half of the NT-33 canopy. Blue snap-on visors were pi ovided to the evaluation pilots. The

  18. Dosimetric Comparison of Split Field and Fixed Jaw Techniques for Large IMRT Target Volumes in the Head and Neck

    International Nuclear Information System (INIS)

    Srivastava, Shiv P.; Das, Indra J.; Kumar, Arvind; Johnstone, Peter A.S.

    2011-01-01

    Some treatment planning systems (TPSs), when used for large-field (>14 cm) intensity-modulated radiation therapy (IMRT), create split fields that produce excessive multiple-leaf collimator segments, match-line dose inhomogeneity, and higher treatment times than nonsplit fields. A new method using a fixed-jaw technique (FJT) forces the jaw to stay at a fixed position during optimization and is proposed to reduce problems associated with split fields. Dosimetric comparisons between split-field technique (SFT) and FJT used for IMRT treatment is presented. Five patients with head and neck malignancies and regional target volumes were studied and compared with both techniques. Treatment planning was performed on an Eclipse TPS using beam data generated for Varian 2100C linear accelerator. A standard beam arrangement consisting of nine coplanar fields, equally spaced, was used in both techniques. Institutional dose-volume constraints used in head and neck cancer were kept the same for both techniques. The dosimetric coverage for the target volumes between SFT and FJT for head and neck IMRT plan is identical within ±1% up to 90% dose. Similarly, the organs at risk (OARs) have dose-volume coverage nearly identical for all patients. When the total monitor unit (MU) and segments were analyzed, SFT produces statistically significant higher segments (17.3 ± 6.3%) and higher MU (13.7 ± 4.4%) than the FJT. There is no match line in FJT and hence dose uniformity in the target volume is superior to the SFT. Dosimetrically, SFT and FJT are similar for dose-volume coverage; however, the FJT method provides better logistics, lower MU, shorter treatment time, and better dose uniformity. The number of segments and MU also has been correlated with the whole body radiation dose with long-term complications. Thus, FJT should be the preferred option over SFT for large target volumes.

  19. [Volume changes to the neck lymph node metastases in head-neck tumors. The evaluation of radiotherapeutic treatment success].

    Science.gov (United States)

    Liszka, G; Thalacker, U; Somogyi, A; Németh, G

    1997-08-01

    This work is engaged with the volume change of neck lymph node metastasis of malignant tumors in the head-neck region during radiotherapy. In 54 patients with head and neck tumors, the volume of neck lymph nodes before and after radiation was measured. The volumetry was done with CT planimetry. The total dose was 66 Gy (2 Gy/d) telecobalt from 2 lateral opponated fields. The time of volume change could be defined with measuring of the half-time and the doubling-time by the help of Schwartz formula. After 10 Gy the volume diminution was about 20% and half-time 24 to 26 days. Afterwards the time of volume diminution picked up speed and finally achieved 60 to 72%. Meanwhile the half-time decreased to the half value. The result was independent of the site of primary tumor, the patient's sex and age. In our opinion the effectivity of radiotherapy can best be judged with defining of the volume change of lymph nodes of the neck.

  20. HydroSoft coil versus HydroCoil for endovascular aneurysm occlusion study: A single center experience

    International Nuclear Information System (INIS)

    Guo Xinbin; Fan Yimu; Zhang Jianning

    2011-01-01

    Background and purpose: The HydroCoil Embolic System (HES) was developed to reduce recurrences of aneurysms relative to platinum coils. But the HydroCoil Embolic System was characterized with many limitations. The manufacturer had recognized the challenge and recently a new design of hydrogel-coated coil-HydroSoft has become available in the market as the new generation HydroCoil. We reported our initial experience using HydroSoft coil versus HydroCoil in our center. Methods: 75 aneurysms embolized primarily using HydroSoft Coils from July 2008 to May 2009 were compared with 66 volume- and shape-matched aneurysms treated with HydroCoils from March 2006 to August 2008. Outcome measures included length and number of coils used, contrast volume, and length of hospital stay. During embolization, a stable framework was first established with bare coils, and hydrogel-coated coils were used subsequently to increase the packing density. Follow-up angiographic results 6 months after treatment were evaluated among some of the patients. Results: Successful coil embolization was achieved in all patients. There were no differences in average total coil length used per aneurysm. There were no differences in length of hospital stay and packing density. HydroSoft coils were more suitable using as the finishing or final coil. HydroSoft coil decreased the procedure-related retreated rates, and aneurysm packing was finished with soft, flexible HydroSoft coil and decreased the neck remnant rates. Follow-up angiography in HydroSoft-treated patients at 6 months revealed aneurysm stability without significant residual neck. Conclusions: HydroSoft coil allowed us to deploy coated coils with good packing density. A slight expansion of these coils at the neck can be expected to reduce neck remnant and potentially inhibit recurrence.

  1. Tumor-Volume Simulation During Radiotherapy for Head-and-Neck Cancer Using a Four-Level Cell Population Model

    International Nuclear Information System (INIS)

    Chvetsov, Alexei V.; Dong Lei; Palta, Jantinder R.; Amdur, Robert J.

    2009-01-01

    Purpose: To develop a fast computational radiobiologic model for quantitative analysis of tumor volume during fractionated radiotherapy. The tumor-volume model can be useful for optimizing image-guidance protocols and four-dimensional treatment simulations in proton therapy that is highly sensitive to physiologic changes. Methods: The analysis is performed using two approximations: (1) tumor volume is a linear function of total cell number and (2) tumor-cell population is separated into four subpopulations: oxygenated viable cells, oxygenated lethally damaged cells, hypoxic viable cells, and hypoxic lethally damaged cells. An exponential decay model is used for disintegration and removal of oxygenated lethally damaged cells from the tumor. Results: We tested our model on daily volumetric imaging data available for 14 head-and-neck cancer patients treated with an integrated computed tomography/linear accelerator system. A simulation based on the averaged values of radiobiologic parameters was able to describe eight cases during the entire treatment and four cases partially (50% of treatment time) with a maximum 20% error. The largest discrepancies between the model and clinical data were obtained for small tumors, which may be explained by larger errors in the manual tumor volume delineation procedure. Conclusions: Our results indicate that the change in gross tumor volume for head-and-neck cancer can be adequately described by a relatively simple radiobiologic model. In future research, we propose to study the variation of model parameters by fitting to clinical data for a cohort of patients with head-and-neck cancer and other tumors. The potential impact of other processes, like concurrent chemotherapy, on tumor volume should be evaluated.

  2. Relative volume measured with magnetic resonance imaging is an articular collapse predictor in hematological pediatric patients with femoral head osteonecrosis.

    Science.gov (United States)

    Ippolito, Davide; Masetto, Alessandro; Talei Franzesi, Cammillo; Bonaffini, Pietro A; Casiraghi, Alessandra; Sironi, Sandro

    2016-08-28

    To assess the potential value of femoral head (FH) volume measurements to predict joint collapse, as compared to articular surface involvement, in post-treatment osteonecrosis (ON) in pediatric patients affected by lymphoproliferative diseases. Considering 114 young patients with lymphoproliferative diseases undergone a lower-limbs magnetic resonance imaging (MRI) examination between November 2006 and August 2012 for a suspected post-treatment ON, we finally considered a total of 13 cases (7 males, mean age 15.2 ± 4.8 years), which developed a FH ON lesions (n = 23). The MRI protocol included coronal short tau inversion recovery and T1-weighted sequences, from the hips to the ankles. During the follow-up (elapsed time: 9.2 ± 2 mo), 13/23 FH articular surface (FHS) developed articular deformity. The first MRI studies with diagnosis of ON were retrospectively analyzed, measuring FH volume (FHV), FHS, ON volume (ONV) and the articular surface involved by ON (ONS). The relative involvement of FHS, in terms of volume [relative volume (RV): ONV/FHV] and articular surface [relative surface (RS): ONS/FHS], was then calculated. By using receiver operating characteristic curve analysis (threshold of 23% of volume involvement), RV predicted articular deformity in 13/13 FHS [sensitivity 100%, specificity 90%, accuracy 95%, positive predictive value (PPV) 93%, negative predictive value (NPV) 100%]. Considering a threshold of 50% of articular involvement, RS predicted articular deformity in 10/13 femoral heads (sensitivity 77%, specificity 100%, accuracy 87%, PPV 100%, NPV 77%). RV might be a more reliable parameter than RS in predicting FH deformity and could represent a potential complementary diagnostic tool in the follow-up of femoral heads ON lesions.

  3. Institutional Clinical Trial Accrual Volume and Survival of Patients With Head and Neck Cancer

    Science.gov (United States)

    Wuthrick, Evan J.; Zhang, Qiang; Machtay, Mitchell; Rosenthal, David I.; Nguyen-Tan, Phuc Felix; Fortin, André; Silverman, Craig L.; Raben, Adam; Kim, Harold E.; Horwitz, Eric M.; Read, Nancy E.; Harris, Jonathan; Wu, Qian; Le, Quynh-Thu; Gillison, Maura L.

    2015-01-01

    Purpose National Comprehensive Cancer Network guidelines recommend patients with head and neck cancer (HNC) receive treatment at centers with expertise, but whether provider experience affects survival is unknown. Patients and Methods The effect of institutional experience on overall survival (OS) in patients with stage III or IV HNC was investigated within a randomized trial of the Radiation Therapy Oncology Group (RTOG 0129), which compared cisplatin concurrent with standard versus accelerated fractionation radiotherapy. As a surrogate for experience, institutions were classified as historically low- (HLACs) or high-accruing centers (HHACs) based on accrual to 21 RTOG HNC trials (1997 to 2002). The effect of accrual volume on OS was estimated by Cox proportional hazards models. Results Median RTOG accrual (1997 to 2002) at HLACs was four versus 65 patients at HHACs. Analysis included 471 patients in RTOG 0129 (2002 to 2005) with known human papillomavirus and smoking status. Patients at HLACs versus HHACs had better performance status (0: 62% v 52%; P = .04) and lower T stage (T4: 26.5% v 35.3%; P = .002) but were otherwise similar. Radiotherapy protocol deviations were higher at HLACs versus HHACs (18% v 6%; P < .001). When compared with HHACs, patients at HLACs had worse OS (5 years: 51.0% v 69.1%; P = .002). Treatment at HLACs was associated with increased death risk of 91% (hazard ratio [HR], 1.91; 95% CI, 1.37 to 2.65) after adjustment for prognostic factors and 72% (HR, 1.72; 95% CI, 1.23 to 2.40) after radiotherapy compliance adjustment. Conclusion OS is worse for patients with HNC treated at HLACs versus HHACs to cooperative group trials after accounting for radiotherapy protocol deviations. Institutional experience substantially influences survival in locally advanced HNC. PMID:25488965

  4. The bar coil for NMR tomograph

    International Nuclear Information System (INIS)

    Bogorodzki, P.; Piatkowski, A.; Wasielewski, J.

    1995-01-01

    The bar coil (bi-planar) for the NMR tomograph, designed for medical diagnostics, has been described. The tests of coil shown that it generates good homogenous magnetic field in a big volume what results in improving of the signal-to-noise ratio

  5. Measurement of heating coil temperature for e-cigarettes with a "top-coil" clearomizer.

    Science.gov (United States)

    Chen, Wenhao; Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A; Kumagai, Kazukiyo

    2018-01-01

    To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers. This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the

  6. Comparison of radiofrequency body coils for MRI at 3 Tesla: a simulation study using parallel transmission on various anatomical targets

    Science.gov (United States)

    Wu, Xiaoping; Zhang, Xiaotong; Tian, Jinfeng; Schmitter, Sebastian; Hanna, Brian; Strupp, John; Pfeuffer, Josef; Hamm, Michael; Wang, Dingxin; Nistler, Juergen; He, Bin; Vaughan, J. Thomas; Ugurbil, Kamil; Van de Moortele, Pierre-Francois

    2015-01-01

    The performance of multichannel transmit coil layouts and parallel transmission (pTx) radiofrequency (RF) pulse design was evaluated with respect to transmit B1 (B1+) homogeneity and Specific Absorption Rate (SAR) at 3 Tesla for a whole body coil. Five specific coils were modeled and compared: a 32-rung birdcage body coil (driven either in a fixed quadrature mode or a two-channel transmit mode), two single-ring stripline arrays (with either 8 or 16 elements), and two multi-ring stripline arrays (with 2 or 3 identical rings, stacked in the z-axis and each comprising eight azimuthally distributed elements). Three anatomical targets were considered, each defined by a 3D volume representative of a meaningful region of interest (ROI) in routine clinical applications. For a given anatomical target, global or local SAR controlled pTx pulses were designed to homogenize RF excitation within the ROI. At the B1+ homogeneity achieved by the quadrature driven birdcage design, pTx pulses with multichannel transmit coils achieved up to ~8 fold reduction in local and global SAR. When used for imaging head and cervical spine or imaging thoracic spine, the double-ring array outperformed all coils including the single-ring arrays. While the advantage of the double-ring array became much less pronounced for pelvic imaging with a substantially larger ROI, the pTx approach still provided significant gains over the quadrature birdcage coil. For all design scenarios, using the 3-ring array did not necessarily improve the RF performance. Our results suggest that pTx pulses with multichannel transmit coils can reduce local and global SAR substantially for body coils while attaining improved B1+ homogeneity, particularly for a “z-stacked” double-ring design with coil elements arranged on two transaxial rings. PMID:26332290

  7. Frequency-difference MIT imaging of cerebral haemorrhage with a hemispherical coil array: numerical modelling.

    Science.gov (United States)

    Zolgharni, M; Griffiths, H; Ledger, P D

    2010-08-01

    The feasibility of detecting a cerebral haemorrhage with a hemispherical MIT coil array consisting of 56 exciter/sensor coils of 10 mm radius and operating at 1 and 10 MHz was investigated. A finite difference method combined with an anatomically realistic head model comprising 12 tissue types was used to simulate the strokes. Frequency-difference images were reconstructed from the modelled data with different levels of the added phase noise and two types of a priori boundary errors: a displacement of the head and a size scaling error. The results revealed that a noise level of 3 m degrees (standard deviation) was adequate for obtaining good visualization of a peripheral stroke (volume approximately 49 ml). The simulations further showed that the displacement error had to be within 3-4 mm and the scaling error within 3-4% so as not to cause unacceptably large artefacts on the images.

  8. Atlas-based automatic segmentation of head and neck organs at risk and nodal target volumes: a clinical validation

    International Nuclear Information System (INIS)

    Daisne, Jean-François; Blumhofer, Andreas

    2013-01-01

    Intensity modulated radiotherapy for head and neck cancer necessitates accurate definition of organs at risk (OAR) and clinical target volumes (CTV). This crucial step is time consuming and prone to inter- and intra-observer variations. Automatic segmentation by atlas deformable registration may help to reduce time and variations. We aim to test a new commercial atlas algorithm for automatic segmentation of OAR and CTV in both ideal and clinical conditions. The updated Brainlab automatic head and neck atlas segmentation was tested on 20 patients: 10 cN0-stages (ideal population) and 10 unselected N-stages (clinical population). Following manual delineation of OAR and CTV, automatic segmentation of the same set of structures was performed and afterwards manually corrected. Dice Similarity Coefficient (DSC), Average Surface Distance (ASD) and Maximal Surface Distance (MSD) were calculated for “manual to automatic” and “manual to corrected” volumes comparisons. In both groups, automatic segmentation saved about 40% of the corresponding manual segmentation time. This effect was more pronounced for OAR than for CTV. The edition of the automatically obtained contours significantly improved DSC, ASD and MSD. Large distortions of normal anatomy or lack of iodine contrast were the limiting factors. The updated Brainlab atlas-based automatic segmentation tool for head and neck Cancer patients is timesaving but still necessitates review and corrections by an expert

  9. Atlas-based automatic segmentation of head and neck organs at risk and nodal target volumes: a clinical validation.

    Science.gov (United States)

    Daisne, Jean-François; Blumhofer, Andreas

    2013-06-26

    Intensity modulated radiotherapy for head and neck cancer necessitates accurate definition of organs at risk (OAR) and clinical target volumes (CTV). This crucial step is time consuming and prone to inter- and intra-observer variations. Automatic segmentation by atlas deformable registration may help to reduce time and variations. We aim to test a new commercial atlas algorithm for automatic segmentation of OAR and CTV in both ideal and clinical conditions. The updated Brainlab automatic head and neck atlas segmentation was tested on 20 patients: 10 cN0-stages (ideal population) and 10 unselected N-stages (clinical population). Following manual delineation of OAR and CTV, automatic segmentation of the same set of structures was performed and afterwards manually corrected. Dice Similarity Coefficient (DSC), Average Surface Distance (ASD) and Maximal Surface Distance (MSD) were calculated for "manual to automatic" and "manual to corrected" volumes comparisons. In both groups, automatic segmentation saved about 40% of the corresponding manual segmentation time. This effect was more pronounced for OAR than for CTV. The edition of the automatically obtained contours significantly improved DSC, ASD and MSD. Large distortions of normal anatomy or lack of iodine contrast were the limiting factors. The updated Brainlab atlas-based automatic segmentation tool for head and neck Cancer patients is timesaving but still necessitates review and corrections by an expert.

  10. Gradient coil system for nuclear magnetic resonance apparatus

    International Nuclear Information System (INIS)

    Frese, G.; Siebold, H.

    1984-01-01

    A gradient coil system for an image-generating, nuclear magnetic resonance tomographic apparatus, particularly a zeugmatographic apparatus. The gradient coil system is arranged on a support body of rotational symmetry, illustratively a hollow cylindrical support body, having an axis which extends along the z-direction of an x, y, z coordinate system which has an origin in the center of imaging region. The gradient coil system contains two pairs of toroidal individual coils which are arranged symmetrically with respect to an x-y plane which extends through the center of the imaging region and which are arranged perpendicular to the z-axis. The direction of current flow in the individual coils of a coil pair is opposite to the direction of flow in the individual coils of the other coil pair. Moreover, further sets of coils are provided for generating field gradient Gx in the x-direction, and Gy in the y-direction. The hollow cylindrical shape of the support body on which the individual coils are arranged permit an imaging region having a substantially spherical volume with a substantially constant field gradient Gz to be achieved. Each of the coils has a predetermined linkage factor which corresponds to the product of the current flowing through the number of coil turns of the coil. Those coils which are arranged further from the plane of symmetry have a substantially larger linkage factor than the coils which are nearer to the plane of symmetry

  11. HydroCoil as an adjuvant to bare platinum coil treatment of 100 cerebral aneurysms

    International Nuclear Information System (INIS)

    Fanning, Noel F.; Berentei, Zsolt; Brennan, Paul R.; Thornton, John

    2007-01-01

    Introduction The overall safety of the HydroCoil, an expansile hybrid hydrogel-platinum coil, is unknown. We report a prospective observational study of our first 100 cerebral aneurysms treated with HydroCoils, focusing on safety and initial efficacy.Methods Indications, procedural complications, clinical and angiographic outcomes were recorded. Packing density, number of coils deployed and angiographic results were compared with those in a matched control group of 100 aneurysms treated solely with bare platinum coils. HydroCoil complication rates were compared to bare platinum coil rates at our institution and in published series. Results Adjuvant HydroCoil treatment led to increased mean percentage aneurysm filling compared to controls (50 ± 21% versus 27 ± 13%, P < 0.001). Immediate posttreatment angiographic results showed significantly (P < 0.001) more complete occlusions and fewer incomplete (<95%) occlusions compared to controls. Intermediate follow-up angiograms (median 7.5 months) in 63 aneurysms showed a trend towards fewer incomplete occlusions with HydroCoil treatment. There were significantly fewer major recurrences with HydroCoil treatment compared to the control treatment (9.5% versus 22.6%, P 0.046). In the adjuvant HydroCoil group, major recurrent aneurysms had significantly less percentage volume packing with HydroCoils than non-recurrent aneurysms (50.3 ± 5.0% versus 65.3 ± 18.0%, P = 0.04). There was a 12% procedural complication rate, 6% procedural morbidity and 1% mortality rate, similar to institutional and reported bare platinum coil complication rates.Conclusion HydroCoils can be safely deployed with a similar complication rate to bare platinum coils. They result in improved aneurysm filling. Intermediate follow-up angiography showed significantly fewer major recurrences. Long-term follow-up is required to confirm initial improved stability. (orig.)

  12. Conception of Brownian coil

    OpenAIRE

    Zhang, Jiayuan

    2018-01-01

    This article proposes a conception of Brownian coil. Brownian coil is a tiny coil with the same size of pollen. Once immersed into designed magnetic field and liquid, the coil will be moved and deformed macroscopically, due to the microscopic thermodynamic molecular collisions. Such deformation and movement will change the magnetic flux through the coil, by which an ElectroMotive Force (EMF) is produced. In this work, Brownian heat exchanger and Brownian generator are further designed to tran...

  13. The New York Head-A precise standardized volume conductor model for EEG source localization and tES targeting.

    Science.gov (United States)

    Huang, Yu; Parra, Lucas C; Haufe, Stefan

    2016-10-15

    In source localization of electroencephalograpic (EEG) signals, as well as in targeted transcranial electric current stimulation (tES), a volume conductor model is required to describe the flow of electric currents in the head. Boundary element models (BEM) can be readily computed to represent major tissue compartments, but cannot encode detailed anatomical information within compartments. Finite element models (FEM) can capture more tissue types and intricate anatomical structures, but with the higher precision also comes the need for semi-automated segmentation, and a higher computational cost. In either case, adjusting to the individual human anatomy requires costly magnetic resonance imaging (MRI), and thus head modeling is often based on the anatomy of an 'arbitrary' individual (e.g. Colin27). Additionally, existing reference models for the human head often do not include the cerebro-spinal fluid (CSF), and their field of view excludes portions of the head and neck-two factors that demonstrably affect current-flow patterns. Here we present a highly detailed FEM, which we call ICBM-NY, or "New York Head". It is based on the ICBM152 anatomical template (a non-linear average of the MRI of 152 adult human brains) defined in MNI coordinates, for which we extended the field of view to the neck and performed a detailed segmentation of six tissue types (scalp, skull, CSF, gray matter, white matter, air cavities) at 0.5mm(3) resolution. The model was solved for 231 electrode locations. To evaluate its performance, additional FEMs and BEMs were constructed for four individual subjects. Each of the four individual FEMs (regarded as the 'ground truth') is compared to its BEM counterpart, the ICBM-NY, a BEM of the ICBM anatomy, an 'individualized' BEM of the ICBM anatomy warped to the individual head surface, and FEMs of the other individuals. Performance is measured in terms of EEG source localization and tES targeting errors. Results show that the ICBM-NY outperforms

  14. Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

    International Nuclear Information System (INIS)

    Souza, Fabio Jose Fabricio de Barros; Evangelista, Anne Rosso; Silva, Juliana Veiga; Madeira, Kristian

    2016-01-01

    Objective: Obstructive sleep apnea syndrome (OSAS) has a high prevalence and carries significant cardiovascular risks. It is important to study new therapeutic approaches to this disease. Positional therapy might be beneficial in reducing the apnea-hypopnea index (AHI). Imaging methods have been employed in order to facilitate the evaluation of the airways of OSAS patients and can be used in order to determine the effectiveness of certain treatments. This study was aimed at determining the influence that upper airway volume, as measured by cervical CT, has in patients diagnosed with OSAS. Methods: This was a quantitative, observational, cross-sectional study. We evaluated 10 patients who had been diagnosed with OSAS by polysomnography and on the basis of the clinical evaluation. All of the patients underwent conventional cervical CT in the supine position. Scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination), and the upper airway volume was compared between the two. Results: The mean age, BMI, and neck circumference were 48.9 ± 14.4 years, 30.5 ± 3.5 kg/m 2 , and 40.3 ± 3.4 cm, respectively. The mean AHI was 13.7 ± 10.6 events/h (range, 6.0-41.6 events/h). The OSAS was classified as mild, moderate, and severe in 70%, 20%, and 10% of the patients, respectively. The mean upper airway volume was 7.9 cm 3 greater when the head was at a 44° upward inclination than when it was in the neutral position, and that difference (17.5 ± 11.0%) was statistically significant (p = 0.002). Conclusions: Elevating the head appears to result in a significant increase in the caliber of the upper airways in OSAS patients. (author)

  15. Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Fabio Jose Fabricio de Barros; Evangelista, Anne Rosso; Silva, Juliana Veiga; Madeira, Kristian, E-mail: fsouzapneumo@hotmail.com [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil). Curso de Medicina; Perico, Gregory Vinicius [Unidade Radiologica Criciuma, SC (Brazil)

    2016-01-15

    Objective: Obstructive sleep apnea syndrome (OSAS) has a high prevalence and carries significant cardiovascular risks. It is important to study new therapeutic approaches to this disease. Positional therapy might be beneficial in reducing the apnea-hypopnea index (AHI). Imaging methods have been employed in order to facilitate the evaluation of the airways of OSAS patients and can be used in order to determine the effectiveness of certain treatments. This study was aimed at determining the influence that upper airway volume, as measured by cervical CT, has in patients diagnosed with OSAS. Methods: This was a quantitative, observational, cross-sectional study. We evaluated 10 patients who had been diagnosed with OSAS by polysomnography and on the basis of the clinical evaluation. All of the patients underwent conventional cervical CT in the supine position. Scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination), and the upper airway volume was compared between the two. Results: The mean age, BMI, and neck circumference were 48.9 ± 14.4 years, 30.5 ± 3.5 kg/m{sup 2} , and 40.3 ± 3.4 cm, respectively. The mean AHI was 13.7 ± 10.6 events/h (range, 6.0-41.6 events/h). The OSAS was classified as mild, moderate, and severe in 70%, 20%, and 10% of the patients, respectively. The mean upper airway volume was 7.9 cm{sup 3} greater when the head was at a 44° upward inclination than when it was in the neutral position, and that difference (17.5 ± 11.0%) was statistically significant (p = 0.002). Conclusions: Elevating the head appears to result in a significant increase in the caliber of the upper airways in OSAS patients. (author)

  16. Progress on large superconducting toroidal field coils

    International Nuclear Information System (INIS)

    Haubenreich, P.N.; Luton, J.N.; Thompson, P.B.; Beard, D.S.

    1979-01-01

    Large superconducting toroidal field coils of competing designs are being produced by six major industrial teams. In the US, teams headed by General Dynamics Convair, General Electric, and Westinghouse are under contract to design and fabricate one coil each to specifications established by the Large Coil Program. A facility for testing 6 coils in a toroidal array at fields to 8 to 12 tesla is under construction at Oak Ridge. Through an international agreement, EURATOM, Japan, and Switzerland will produce one coil each for testing with the US coils. Each test coil will have a 2.5 x 3.5 m D-shape winding bore and is designed to operate at a current of 10 to 18 kA at a peak field of 8T while subjected to pulsed fields of 0.14 T applied in 1.0 s. There are significant differences among the six coil designs: five use NbTi, one Nb 3 Sn; three are cooled by pool boiling helium, three by forced flow; five have welded or bolted stainless steel coil cases, one has aluminum plate structure. All are designed to be cryostable at 8T, with structural margin for extended operation. The three US coil teams are almost or completely finished with detailed design and are now procuring materials and setting up manufacturing equipment. The non-US teams are at various stages of verification testing and design. The GDC and GE coils are scheduled for delivery in the spring of 1981 and the others will be completed a year later. The 11-m diameter vessel at the test facility has been completed and major components of the test stand are being procured. Engineering and procurement to upgrade the helium liquifier-refrigerator system are under way

  17. The repeatability of left ventricular volume assessment by a new ambulatory radionuclide monitoring system during head-up tilt

    International Nuclear Information System (INIS)

    Takase, Bonpei; Hosaka, Haruhiko; Kitamura, Katsuhiro

    2001-01-01

    The precise measurement of changes in left ventricular volume is important to elucidate the mechanisms of neurally mediated syncope. This study was conducted to determine whether or not a brand-new ambulatory radionuclide monitoring system (C-VEST system) can be clinically used to easily and precisely measure left ventricular volume and function in tilt testing. To assess the repeatability of the C-VEST system, 12 healthy volunteers (mean age 24±4 years old) underwent 20 minute head-up tilt testing and we measured the temporal changes in left ventricular volume and ejection fraction twice a day (first and second studies). To investigate the changes in the C-VEST measurements and the detector position in the first and second studies, tilt testing was performed with an 80-degree passive tilt, which is the same as the standard procedure used in diagnosing neurally mediated syncope. The coefficient of repeatability for both the C-VEST and detector position was well within the clinical range (coefficient of repeatability in left ventricular volume ranged from 1.7 to 2.8; coefficient of repeatability in the detector position ranged from 2.3 to 3.1). Precise evaluation of the left ventricular volume can be achieved by an ambulatory radionuclide monitoring system in tilt testing. (author)

  18. Deep brain transcranial magnetic stimulation using variable "Halo coil" system

    Science.gov (United States)

    Meng, Y.; Hadimani, R. L.; Crowther, L. J.; Xu, Z.; Qu, J.; Jiles, D. C.

    2015-05-01

    Transcranial Magnetic Stimulation has the potential to treat various neurological disorders non-invasively and safely. The "Halo coil" configuration can stimulate deeper regions of the brain with lower surface to deep-brain field ratio compared to other coil configurations. The existing "Halo coil" configuration is fixed and is limited in varying the site of stimulation in the brain. We have developed a new system based on the current "Halo coil" design along with a graphical user interface system that enables the larger coil to rotate along the transverse plane. The new system can also enable vertical movement of larger coil. Thus, this adjustable "Halo coil" configuration can stimulate different regions of the brain by adjusting the position and orientation of the larger coil on the head. We have calculated magnetic and electric fields inside a MRI-derived heterogeneous head model for various positions and orientations of the coil. We have also investigated the mechanical and thermal stability of the adjustable "Halo coil" configuration for various positions and orientations of the coil to ensure safe operation of the system.

  19. Ocular MR imaging. Evaluation of different coil setups in a phantom study

    International Nuclear Information System (INIS)

    Erb-Eigner, Katharina; Warmuth, Carsten; Taupitz, Matthias; Bertelmann, Eckart; Hamm, Bernd; Asbach, Patrick

    2013-01-01

    Small loop surface coils are generally recommended for ocular magnetic resonance (MR) imaging, but the optimal coil setup has not been systematically investigated. In this phantom study, we investigated which coil setup of those coils available for our MR imaging system provides the highest signal-to-noise ratio (SNR) in ocular MR imaging at 1.5 tesla. Using a phantom to simulate the eyeball and the orbital fat, we employed loop surface coils of 4- and 6-cm diameter and a multi-channel head coil to obtain images using a T 1 -weighted spin-echo sequence and then measured the SNR for each coil and coil combination. Use of the 6-cm loop coil alone yielded the highest mean SNR (27.5). Even in superficial regions (mesial and temporal), the SNR was higher using the 6-cm loop coil (33.6 and 45.5) than the 4-cm loop coil (28.0 and 33.8). Additional use of the head coil reduced the mean SNR to 10.4. This quantitative analysis suggests that use of a 6-cm loop surface coil offers the best results in ocular MR imaging. Combinations of loop coils or additional use of a head coil cannot be recommended because higher noise degrades image quality. (author)

  20. Comparison of shape memory polymer foam versus bare metal coil treatments in an in vivo porcine sidewall aneurysm model.

    Science.gov (United States)

    Horn, John; Hwang, Wonjun; Jessen, Staci L; Keller, Brandis K; Miller, Matthew W; Tuzun, Egemen; Hartman, Jonathan; Clubb, Fred J; Maitland, Duncan J

    2017-10-01

    The endovascular delivery of platinum alloy bare metal coils has been widely adapted to treat intracranial aneurysms. Despite the widespread clinical use of this technique, numerous suboptimal outcomes are possible. These may include chronic inflammation, low volume filling, coil compaction, and recanalization, all of which can lead to aneurysm recurrence, need for retreatment, and/or potential rupture. This study evaluates a treatment alternative in which polyurethane shape memory polymer (SMP) foam is used as an embolic aneurysm filler. The performance of this treatment method was compared to that of bare metal coils in a head-to-head in vivo study utilizing a porcine vein pouch aneurysm model. After 90 and 180 days post-treatment, gross and histological observations were used to assess aneurysm healing. At 90 days, the foam-treated aneurysms were at an advanced stage of healing compared to the coil-treated aneurysms and showed no signs of chronic inflammation. At 180 days, the foam-treated aneurysms exhibited an 89-93% reduction in cross-sectional area; whereas coiled aneurysms displayed an 18-34% area reduction. The superior healing in the foam-treated aneurysms at earlier stages suggests that SMP foam may be a viable alternative to current treatment methods. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1892-1905, 2017. © 2016 Wiley Periodicals, Inc.

  1. Focused surface coil for MR imaging of the pituitary

    International Nuclear Information System (INIS)

    Harms, S.E.; Sherry, C.S.; Youshimura, L.; Lokken, R.; Hyde, J.S.

    1987-01-01

    A specially designed surface coil for pituitary MR imaging results in improved image quality over that achieved with conventional pituitary Mr imaging. The coil consists of connected planar pair coils with a variable intercoil distance to accommodate differences in head size. The sensitive field is focused deep to the surface between the two planar pairs. This arrangement optimizes the signal-to-noise ratio and allows better gradient magnification of the pituitary region. Fifteen subjects with a variety of pituitary disorders were imaged

  2. Design of a quadrature surface coil for hyperpolarized 13C MRS cardiac metabolism studies in pigs

    DEFF Research Database (Denmark)

    Giovannetti, G.; Frijia, F.; Hartwig, V.

    2013-01-01

    , the performance of the quadrature coil was compared with the single TX/RX circular and TX/RX butterfly coil, in order to verify the advantage of the proposed configuration over the single coils throughout the volume of interest for cardiac imaging in pig. Finally, the quadrature surface coil was tested...

  3. Water cooling coil

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, S; Ito, Y; Kazawa, Y

    1975-02-05

    Object: To provide a water cooling coil in a toroidal nuclear fusion device, in which coil is formed into a small-size in section so as not to increase dimensions, weight or the like of machineries including the coil. Structure: A conductor arranged as an outermost layer of a multiple-wind water cooling coil comprises a hollow conductor, which is directly cooled by fluid, and as a consequence, a solid conductor disposed interiorly thereof is cooled indirectly.

  4. Dose-volume modeling of salivary function in patients with head-and-neck cancer receiving radiotherapy

    International Nuclear Information System (INIS)

    Blanco, Angel I.; Chao, K.S. Clifford; El Naqa, Issam; Franklin, Gregg E.; Zakarian, Konstantin; Vicic, Milos; Deasy, Joseph O.

    2005-01-01

    Purpose: We investigated the factors that affect salivary function after head-and-neck radiotherapy (RT), including parotid gland dose-volume effects, potential compensation by less-irradiated gland tissue, and functional recovery over time. Methods and Materials: Sixty-five patients with head-and-neck tumors were enrolled in a prospective salivary function study. RT was delivered using intensity-modulated RT (n = 45), forward-planning three-dimensional conformal RT (n = 14), or three-dimensional conformal RT with an intensity-modulated RT boost (n = 6). Whole salivary flow was measured before therapy and at 6 months (n = 61) and 12 months (n = 31) after RT. A wide variety of dose-volume models to predict post-RT salivary function were tested. Xerostomia was defined according to the subjective, objective, management, analytic (SOMA) criteria as occurring when posttreatment salivary function was s ] = 0.46, p s = 0.73), stimulated saliva flow at 12 months (R s = 0.54), and quality-of-life score at 6 months (R s = 0.35) after RT. Conclusion: Stimulated parotid salivary gland dose-volume models strongly correlated with both stimulated salivary function and quality-of-life scores at 6 months after RT. The mean stimulated saliva flow rates improved from 6 to 12 months after RT. Salivary function, in each gland, appeared to be lost exponentially at a rate of approximately 5%/1 Gy of mean dose. Additional research is necessary to distinguish among the models for use in treatment planning. The incidence of xerostomia was significantly decreased when the mean dose of at least one parotid gland was kept to <25.8 Gy with conventional fractionation. However, even lower mean doses imply increased late salivary function

  5. Study on the performance improvement of the high temperature superconducting coil with several separated coils at the edges

    International Nuclear Information System (INIS)

    Ishiguri, S.; Oka, T.; Fukui, S.; Ogawa, J.; Sato, T.

    2008-01-01

    In designing high temperature superconducting (HTS) coils, it is important to secure large magnetic fields and stored energy using shorter tape length. Thus, it is necessary to improve the transport current performance of the coils. The critical current and n-value of an HTS tape depend on magnetic fields and flux angles under constant temperature. Considering these dependencies, we established a model to analyze coil critical current. This model clarifies that relatively large electric fields are generated at the coil edges. This adversely affects the transport current performance. In this study, the coil edge is separated into several coils, keeping the total tape length constant. This increases the coil critical current, stored energy, central magnetic field, and also the coil volume, which contains vacancies created by the separation. To estimate coil performance, we calculated the stored energy density, whose denominator is the increased coil volume. This stored energy density reaches its maximum value when the number of the separated coils is eight. At this optimum separation, the central magnetic field increases by 13%, and the stored energy improves by 43%, compared to a rectangular coil wound with the same tape length

  6. Importance of the initial volume of parotid glands in xerostomia for patients with head and neck cancers treated with IMRT

    International Nuclear Information System (INIS)

    Nishimura, Yasumasa; Nakamatsu, Kiyoshi; Shibata, Toru; Kanamori, Shuichi; Koike, Ryuta; Okumura, Masahiko; Suzuki, Minoru

    2005-01-01

    Our aim was to evaluate predictors of xerostomia in patients with head and neck cancers treated with intensity-modulated radiation therapy (IMRT). Thirty-three patients with pharyngeal cancer were evaluated for xerostomia after having been treated with IMRT. All patients were treated with whole-neck irradiation of 46-50 Gy by IMRT, followed by boost IMRT to the high-risk clinical target volume to a total dose of 56-70 Gy in 28-35 fractions (median, 68 Gy). For boost IMRT, a second computed tomography (CT-2) scan was done in the third to fourth week of IMRT. Xerostomia was scored 3-4 months after the start of IMRT. The mean doses to the contralateral and ipsilateral parotid glands were 24.0±6.2 and 30.3±6.6 Gy, respectively. Among the 33 patients, xerostomia of grades 0, 1, 2 and 3 was noted in one, 18, 12 and two patients, respectively. Although the mean dose to the parotid glands was not correlated with the grade of xerostomia, the initial volume of the parotid glands was correlated with the grade of xerostomia (P=0.04). Of 17 patients with small parotid glands (≤38.8 ml) on initial CT (CT-1), 11 (65%) showed grade 2 or grade 3 xerostomia, whereas only three (19%) of 16 patients with larger parotid glands showed grade 2 xerostomia (P<0.05). The mean volume of the parotid glands on CT-1 was 43.1±15.2 ml, but decreased significantly to 32.0±11.4 ml (74%) on CT-2 (P<0.0001). Initial volumes of the parotid glands are significantly correlated with the grade of xerostomia in patients treated with IMRT. The volume of the parotid glands decreased significantly during the course of IMRT. (author)

  7. Evaluation of atlas based auto-segmentation for head and neck target volume delineation in adaptive/replan IMRT

    International Nuclear Information System (INIS)

    Speight, R; Lindsay, R; Harding, R; Sykes, J; Karakaya, E; Prestwich, R; Sen, M

    2014-01-01

    IMRT for head and neck patients requires clinicians to delineate clinical target volumes (CTV) on a planning-CT (>2hrs/patient). When patients require a replan-CT, CTVs must be re-delineated. This work assesses the performance of atlas-based autosegmentation (ABAS), which uses deformable image registration between planning and replan-CTs to auto-segment CTVs on the replan-CT, based on the planning contours. Fifteen patients with planning-CT and replan-CTs were selected. One clinician delineated CTVs on the planning-CTs and up to three clinicians delineated CTVs on the replan-CTs. Replan-CT volumes were auto-segmented using ABAS using the manual CTVs from the planning-CT as an atlas. ABAS CTVs were edited manually to make them clinically acceptable. Clinicians were timed to estimate savings using ABAS. CTVs were compared using dice similarity coefficient (DSC) and mean distance to agreement (MDA). Mean inter-observer variability (DSC>0.79 and MDA<2.1mm) was found to be greater than intra-observer variability (DSC>0.91 and MDA<1.5mm). Comparing ABAS to manual CTVs gave DSC=0.86 and MDA=2.07mm. Once edited, ABAS volumes agreed more closely with the manual CTVs (DSC=0.87 and MDA=1.87mm). The mean clinician time required to produce CTVs reduced from 169min to 57min when using ABAS. ABAS segments volumes with accuracy close to inter-observer variability however the volumes require some editing before clinical use. Using ABAS reduces contouring time by a factor of three.

  8. NCSX Trim Coil Design

    International Nuclear Information System (INIS)

    Kalish, M.; Brooks, A.; Rushinski, J.; Upcavage, R.

    2009-01-01

    The National Compact Stellarator Experiment (NCSX) was being constructed at the Princeton Plasma Physics Laboratory in partnership with Oak Ridge National Laboratory before work was stopped in 2008. The objective of this experiment was to develop the stellarator concept and evaluate it's potential as a model for future fusion power plants. Stellarator design requires very precisely positioned Modular Coils of complex shape to form 3D plasmas. In the design of NCSX, Trim Coils were required to compensate for both the positioning of the coils during assembly and the fabrication tolerances of the Modular Coils. Use of the Trim Coils allowed for larger tolerances increasing ease of assembly and decreasing overall cost. A set of Trim coils was developed to suppress the toroidal flux in island regions due to misalignment, magnetic materials, and eddy currents. The requirement imposed upon the design forced the toroidal flux in island regions below 10% of the total toroidal flux in the plasma. An analysis was first performed to evaluate candidate Trim Coil configurations iterating both the size, number, and position of the coils. The design was optimized considering both performance and cost while staying within the tight restraints presented by the space limited geometry. The final design of the Trim Coils incorporated a 48 Coil top bottom symmetric set. Fabrication costs were minimized by having only two coil types and using a planar conventional design with off the shelf commercial conductor. The Trim Coil design incorporated supports made from simple structural shapes assembled together in a way which allowed for adjustment as well as accommodation for the tolerance build up on the mating surfaces. This paper will summarize the analysis that led to the optimization of the Trim Coils set, the trim coil mechanical design, thermal and stress analysis, and the design of the supporting Trim Coil structure

  9. Dual coil ignition system

    Energy Technology Data Exchange (ETDEWEB)

    Huberts, Garlan J.; Qu, Qiuping; Czekala, Michael Damian

    2017-03-28

    A dual coil ignition system is provided. The dual coil ignition system includes a first inductive ignition coil including a first primary winding and a first secondary winding, and a second inductive ignition coil including a second primary winding and a second secondary winding, the second secondary winding connected in series to the first secondary winding. The dual coil ignition system further includes a diode network including a first diode and a second diode connected between the first secondary winding and the second secondary winding.

  10. Biomaterials Made from Coiled-Coil Peptides.

    Science.gov (United States)

    Conticello, Vincent; Hughes, Spencer; Modlin, Charles

    The development of biomaterials designed for specific applications is an important objective in personalized medicine. While the breadth and prominence of biomaterials have increased exponentially over the past decades, critical challenges remain to be addressed, particularly in the development of biomaterials that exhibit highly specific functions. These functional properties are often encoded within the molecular structure of the component molecules. Proteins, as a consequence of their structural specificity, represent useful substrates for the construction of functional biomaterials through rational design. This chapter provides an in-depth survey of biomaterials constructed from coiled-coils, one of the best-understood protein structural motifs. We discuss the utility of this structurally diverse and functionally tunable class of proteins for the creation of novel biomaterials. This discussion illustrates the progress that has been made in the development of coiled-coil biomaterials by showcasing studies that bridge the gap between the academic science and potential technological impact.

  11. Evaluation of absorbed dose in organs far from the target volume for different therapies of head and neck cancer

    International Nuclear Information System (INIS)

    Pletsch, Cristiana

    2013-01-01

    Many advances in radiotherapy are the result of innovations in technology and engineering as well as the information technology revolution applied to the treatment planning of patients. The intensity modulated radiation therapy (lMRT) is a sophisticated treatment technique that allows the concentration of the dose prescribed by radiotherapist in tumor volume, while sparing healthy tissues that surround it. However, the disadvantage of the technique is a potential induction of secondary cancers in distant organs related to the target volume due to leakage and scattered radiation, which generate these higher doses to the distant organs when compared to those measured in conventional treatments. These higher doses are is due to the greater use of monitor units and a larger amount of treatment fields. In this study the absorbed dose values in distant organs from the head and neck region were assessed, comparing conventional treatments and treatments using the IMRT techniques. The evaluation was made considering the assessment of dose in radiological significant organs distant from the treatment area. All measurements were performed using the RANDO Alderson anthropomorphic phantom that has internal components equivalent to muscle, bones and lungs and is sliced for placing thermoluminescent detectors in appropriate holes existing in the slices. This phantom, tilled with TLD-100 dosimeters, was submitted to a head and neck treatment with a cobalt-60 irradiator and a Trilogy linear accelerator. Three treatments were carried out with the accelerator, namely a conventional one and two treatments of IMRT with different complexities, all treatments using the 6MV beam. The results show that IMRT techniques generate large doses in distant organs when compared to those generated due to the conventional 6 MV beam treatment. However, these doses are not very different from those measured in the case of 60 Co treatment. (author)

  12. Blood flow and blood volume in the femoral heads of healthy adults according to age. Measurement with positron emission tomography (PET)

    International Nuclear Information System (INIS)

    Kubo, Toshikazu; Kimori, Kokuto; Nakamura, Fuminori; Inoue, Shigehiro; Fujioka, Mikihiro; Ueshima, Keiichiro; Hirasawa, Yasusuke; Ushijima, Yo; Nishimura, Tsunehiko

    2001-01-01

    To deepen understanding of hemodynamics in the femoral head, i.e., the essential factor in clarifying pathogenesis of hip disorders, this study examined blood flow and blood volume in the femoral heads of healthy adults, and their changes with age, by using positron emission tomography (PET). In 16 healthy adult males (age: 20-78 years old, mean age: 42 years), blood flow was measured by means of the H 2 15 O dynamic study method, and blood volume was measured by means of the 15 O-labeled carbon monoxide bolus inhalation method. Blood flow was 1.68-6.47 ml/min/100 g (mean ±SD: 3.52±1.2), and blood volume was 1.67-6.03 ml/100 g (mean ±SD: 3.00±1.27). Blood flow significantly decreased (p<0.01) with age, and blood volume significantly increased (P<0.05). PET was useful in the measurement of blood flow and blood volume in the femoral heads. With age, physiological hemodynamic changes also increased in femoral heads. (author)

  13. Continuous infusion of small-volume fluid resuscitation in the treatment of combined uncontrolled hemorrhagic shock and head injury

    International Nuclear Information System (INIS)

    Hayrettin, O.; Yagmur, Y.; Tas, A.; Topcu, S.; Orak, M.

    2007-01-01

    To determine the effect of continuous limited fluid resuscitation on the hemodynamic response and survival in rats in a model of uncontrolled hemorrhage shock due to Massive Splenic Injury (MSI) and Head Injury (HI). Seventy Sprague-Dawley rats were used in this study. Group 1 rats (n=10) was sham-operated. In group 2 (n=10), only Massive Splenic Injury (MSI) was performed and untreated. In group 3 (n=10), only head injury (HI) was performed and untreated. In group 4 (n=10), HI and MSI were performed and were untreated. In group 5 (n=10), HI and MSI were performed and 15 minutes later treated with 7.5% NaCl. In group 6 (n=10), HI and MSI were performed, and rats were treated with Ringer's Lactate (RL) solution. In group 7 (n=10), HI and MSI were performed, rats were treated with 0.9 % NaCl. In groups 2,4,5,6 and 7 midline incision was reopened and splenectomy was performed at 45 minutes. In group 4 rats, Mean Arterial Pressure (MAP) was decreased from 104 +- 6.1 mmHg to 75 +- 19.5 mmHg at 15 minutes; heart rate decreased from 357+- 24.9 beats/min to 321 +- 62.1 beats/min and hematocrit decreased from 46 +- 1.3 % to 43 +- 2.5 % (p<0.01). Similar early changes in MAP, heart rate and hematocrit were observed in groups 5, 6, and 7, at 15 minutes. At 45,60 and 120 minutes, in fluid resuscitated rats (group 5,6,7) MAP, heart rate and hematocrit values were measured higher than group 2 and 4 (p<0.01 for all). At 120 min. in group 6, hematocrit was higher than group 4, 5 and 7, in group 6, total blood loss after splenectomy was calculated at 20 +- 2.4% of blood volume and was the best value compared to other fluid resuscitated group 5 and 7 (28% and 27% of blood volume) (p<0.01). Mortality was lower in all fluid resuscitated groups when compared to group 3 and 4 (p< 0.05). The median survival time was again higher in fluid resuscitated groups. Continuous infusion of 7.5% NaCl, RL and 0.9 % NaCl following uncontrolled hemorrhagic shock with massive splenic injury and

  14. Interleaved 3D-CNNs for joint segmentation of small-volume structures in head and neck CT images.

    Science.gov (United States)

    Ren, Xuhua; Xiang, Lei; Nie, Dong; Shao, Yeqin; Zhang, Huan; Shen, Dinggang; Wang, Qian

    2018-02-26

    Accurate 3D image segmentation is a crucial step in radiation therapy planning of head and neck tumors. These segmentation results are currently obtained by manual outlining of tissues, which is a tedious and time-consuming procedure. Automatic segmentation provides an alternative solution, which, however, is often difficult for small tissues (i.e., chiasm and optic nerves in head and neck CT images) because of their small volumes and highly diverse appearance/shape information. In this work, we propose to interleave multiple 3D Convolutional Neural Networks (3D-CNNs) to attain automatic segmentation of small tissues in head and neck CT images. A 3D-CNN was designed to segment each structure of interest. To make full use of the image appearance information, multiscale patches are extracted to describe the center voxel under consideration and then input to the CNN architecture. Next, as neighboring tissues are often highly related in the physiological and anatomical perspectives, we interleave the CNNs designated for the individual tissues. In this way, the tentative segmentation result of a specific tissue can contribute to refine the segmentations of other neighboring tissues. Finally, as more CNNs are interleaved and cascaded, a complex network of CNNs can be derived, such that all tissues can be jointly segmented and iteratively refined. Our method was validated on a set of 48 CT images, obtained from the Medical Image Computing and Computer Assisted Intervention (MICCAI) Challenge 2015. The Dice coefficient (DC) and the 95% Hausdorff Distance (95HD) are computed to measure the accuracy of the segmentation results. The proposed method achieves higher segmentation accuracy (with the average DC: 0.58 ± 0.17 for optic chiasm, and 0.71 ± 0.08 for optic nerve; 95HD: 2.81 ± 1.56 mm for optic chiasm, and 2.23 ± 0.90 mm for optic nerve) than the MICCAI challenge winner (with the average DC: 0.38 for optic chiasm, and 0.68 for optic nerve; 95HD: 3.48 for

  15. Dysphagia after definitive radiotherapy for head and neck cancer. Correlation of dose-volume parameters of the pharyngeal constrictor muscles

    Energy Technology Data Exchange (ETDEWEB)

    Deantonio, L.; Masini, L. [University Hospital ' Maggiore della Carita' , Novara (Italy). Radiotherapy; Brambilla, M. [University Hospital ' Maggiore della Carita' , Novara (Italy). Medical Physics; Pia, F. [University Hospital ' Maggiore della Carita' , Novara (Italy). Otolaryngology; University of ' Piemonte Orientale' , Novara (Italy). Dept. of Medical Sciences; Krengli, M. [University Hospital ' Maggiore della Carita' , Novara (Italy). Radiotherapy; University of ' Piemonte Orientale' , Novara (Italy). Dept. of Translational Medicine and BRMA

    2013-03-15

    Background: Dysphagia is a complication of head and neck cancer patients undergoing radiotherapy (RT). We analysed frequency and severity of swallowing dysfunction and correlated these findings with dose-volume histograms (DVHs) of the pharyngeal constrictor muscles. Methods: A total of 50 patients treated by radical RT were enrolled. DVHs of constrictor muscles were correlated with acute and late dysphagia and with the items of three quality of life questionnaires. Results: Mean dose to superior and middle constrictor muscles (SCM, MCM), partial volume of SCM and MCM receiving a dose {>=} 50 Gy dose to the whole constrictor muscles {>=} 60 Gy and tumour location were associated to late dysphagia at univariate analysis. Mean dose to the MCM was the only statistically significant predictor of late dysphagia at the multivariable analysis. Conclusion: The study shows a significant relationship between long-term dysphagia and mean doses to SCM, MCM, whole constrictor muscles, and oropharyngeal tumour. This finding suggests a potential advantage in reducing the RT dose to swallowing structures to avoid severe dysphagia. (orig.)

  16. Dysphagia after definitive radiotherapy for head and neck cancer. Correlation of dose-volume parameters of the pharyngeal constrictor muscles

    International Nuclear Information System (INIS)

    Deantonio, L.; Masini, L.; Brambilla, M.; Pia, F.; University of 'Piemonte Orientale', Novara; Krengli, M.; University of 'Piemonte Orientale', Novara

    2013-01-01

    Background: Dysphagia is a complication of head and neck cancer patients undergoing radiotherapy (RT). We analysed frequency and severity of swallowing dysfunction and correlated these findings with dose-volume histograms (DVHs) of the pharyngeal constrictor muscles. Methods: A total of 50 patients treated by radical RT were enrolled. DVHs of constrictor muscles were correlated with acute and late dysphagia and with the items of three quality of life questionnaires. Results: Mean dose to superior and middle constrictor muscles (SCM, MCM), partial volume of SCM and MCM receiving a dose ≥ 50 Gy dose to the whole constrictor muscles ≥ 60 Gy and tumour location were associated to late dysphagia at univariate analysis. Mean dose to the MCM was the only statistically significant predictor of late dysphagia at the multivariable analysis. Conclusion: The study shows a significant relationship between long-term dysphagia and mean doses to SCM, MCM, whole constrictor muscles, and oropharyngeal tumour. This finding suggests a potential advantage in reducing the RT dose to swallowing structures to avoid severe dysphagia. (orig.)

  17. Clipping of tumour resection margins allows accurate target volume delineation in head and neck cancer adjuvant radiation therapy

    International Nuclear Information System (INIS)

    Bittermann, Gido; Wiedenmann, Nicole; Bunea, Andrei; Schwarz, Steffen J.; Grosu, Anca-L.; Schmelzeisen, Rainer; Metzger, Marc C.

    2015-01-01

    Background: Accurate tumour bed localisation is a key requirement for adjuvant radiotherapy. A new procedure is described for head and neck cancer treatment that improves tumour bed localisation using titanium clips. Materials and methods: Following complete local excision of the primary tumour, the tumour bed was marked with titanium clips. Preoperative gross target volume (GTV) and postoperative tumour bed were examined and the distances between the centres of gravity were evaluated. Results: 49 patients with squamous cell carcinoma of the oral cavity were prospectively enrolled in this study. All patients underwent tumour resection, neck lymph node dissection and defect reconstruction in one stage. During surgery, 7–49 clips were placed in the resection cavity. Surgical clip insertion was successful in 88% (n = 43). Clip identification and tumour bed delineation was successful in all 43 patients. The overall distance between the centres of gravity of the preoperative tumour extension to the tumour bed was 0.9 cm. A significant relationship between the preoperative tumour extension and the postoperative tumour bed volume could be demonstrated. Conclusion: We demonstrate a precise delineation of the former tumour cavity. Improvements in tumour bed delineation allow an increase of accuracy for adjuvant treatment

  18. Superconducting magnetic coil

    Science.gov (United States)

    Aized, Dawood; Schwall, Robert E.

    1996-06-11

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.

  19. Cooling and dehumidifying coils

    International Nuclear Information System (INIS)

    Murthy, M.V.K.

    1988-01-01

    The operating features of cooling and dehumidifying coils and their constructional details are discussed. The heat transfer relations as applicable to the boiling refrigerant and a single phase fluid are presented. Methods of accounting for the effect of moisture condensation on the air side heat transfer coefficient and the fin effectiveness are explained. The logic flow necessary to analyze direct expansion coils and chilled water coils is discussed

  20. The JET divertor coil

    International Nuclear Information System (INIS)

    Last, J.R.; Froger, C.; Sborchia, C.

    1989-01-01

    The divertor coil is mounted inside the Jet vacuum vessel and is able to carry 1 MA turns. It is of conventional construction - water cooled copper, epoxy glass insulation -and is contained in a thin stainless steel case. The coil has to be assembled, insulated and encased inside the Jet vacuum vessel. A description of the coil is given, together with technical information (including mechanical effects on the vacuum vessel), an outline of the manufacture process and a time schedule. (author)

  1. Auto-segmentation of low-risk clinical target volume for head and neck radiation therapy.

    Science.gov (United States)

    Yang, Jinzhong; Beadle, Beth M; Garden, Adam S; Gunn, Brandon; Rosenthal, David; Ang, Kian; Frank, Steven; Williamson, Ryan; Balter, Peter; Court, Laurence; Dong, Lei

    2014-01-01

    To investigate atlas-based auto-segmentation methods to improve the quality of the delineation of low-risk clinical target volumes (CTVs) of unilateral tonsil cancers. Sixteen patients received intensity modulated radiation therapy for left tonsil tumors. These patients were treated by a total of 8 oncologists, who delineated all contours manually on the planning CT image. We chose 6 of the patients as atlas cases and used atlas-based auto-segmentation to map each the atlas CTV to the other 10 patients (test patients). For each test patient, the final contour was produced by combining the 6 individual segmentations from the atlases using the simultaneous truth and performance level estimation algorithm. In addition, for each test patient, we identified a single atlas that produced deformed contours best matching the physician's manual contours. The auto-segmented contours were compared with the physician's manual contours using the slice-wise Hausdorff distance (HD), the slice-wise Dice similarity coefficient (DSC), and a total volume overlap index. No single atlas consistently produced good results for all 10 test cases. The multiatlas segmentation achieved a good agreement between auto-segmented contours and manual contours, with a median slice-wise HD of 7.4 ± 1.0 mm, median slice-wise DSC of 80.2% ± 5.9%, and total volume overlap of 77.8% ± 3.3% over the 10 test cases. For radiation oncologists who contoured both the test case and one of the atlas cases, the best atlas for a test case had almost always been contoured by the oncologist who had contoured that test case, indicating that individual physician's practice dominated in target delineation and was an important factor in optimal atlas selection. Multiatlas segmentation may improve the quality of CTV delineation in clinical practice for unilateral tonsil cancers. We also showed that individual physician's practice was an important factor in selecting the optimal atlas for atlas-based auto

  2. Comparison of five segmentation tools for 18F-fluoro-deoxy-glucose-positron emission tomography-based target volume definition in head and neck cancer.

    NARCIS (Netherlands)

    Schinagl, D.A.X.; Vogel, W.V.; Hoffmann, A.L.; Dalen, J.A. van; Oyen, W.J.G.; Kaanders, J.H.A.M.

    2007-01-01

    PURPOSE: Target-volume delineation for radiation treatment to the head and neck area traditionally is based on physical examination, computed tomography (CT), and magnetic resonance imaging. Additional molecular imaging with (18)F-fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) may

  3. Characteristics of parallel reverse coil inductors with different current ratio in coils used for melting in a suspension state

    International Nuclear Information System (INIS)

    Fogel', A.A.; Sidorova, T.A.; Smirnov, V.V.; Mezdrogina, M.M.

    1975-01-01

    The paper studies the effect of the ratio of the currents in the coils of an inductor with a parallel-switched ''reverse coil'', where the ratio of the current in the upper coil to that in the lower coil is 0.72. A region of stable dependence of liquid niobium characterized by upper and lower limits has been found. The maximum permissible volume of liquid niobium increases as the ratio of current in the upper coil to current in the lower coil decreases. The temperature dependences of niobium on the voltage in the inductor have been derived. Experiments have shown that the greater the capillary constant of niobium, the larger the region of stable dependence of liquid niobium, the larger the range of possible temperature regulation and the larger the maximum permissible volume. (N.K.)

  4. Determination and delineation of nodal target volumes for head-and-neck cancer based on patterns of failure in patients receiving definitive and postoperative IMRT

    International Nuclear Information System (INIS)

    Chao, K.S. Clifford; Wippold, Franz J.; Ozyigit, Gokhan; Tran, Binh N.; Dempsey, James F.

    2002-01-01

    Purpose: We present the guidelines for target volume determination and delineation of head-and-neck lymph nodes based on the analysis of the patterns of nodal failure in patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Data pertaining to the natural course of nodal metastasis for each head-and-neck cancer subsite were reviewed. A system was established to provide guidance for nodal target volume determination and delineation. Following these guidelines, 126 patients (52 definitive, 74 postoperative) were treated between February 1997 and December 2000 with IMRT for head-and-neck cancer. The median follow-up was 26 months (range 12-55), and the patterns of nodal failure were analyzed. Results: These guidelines define the nodal target volume based on the location of the primary tumor and the probability of microscopic metastasis to the ipsilateral and contralateral (Level I-V) nodal regions. Following these guidelines, persistent or recurrent nodal disease was found in 6 (12%) of 52 patients receiving definitive IMRT, and 7 (9%) of 74 patients receiving postoperative IMRT had failure in the nodal region. Conclusion: On the basis of our clinical experience in implementing inverse-planning IMRT for head-and-neck cancer, we present guidelines using a simplified, but clinically relevant, method for nodal target volume determination and delineation. The intention was to provide a foundation that enables different institutions to exchange clinical experiences in head-and-neck IMRT. These guidelines will be subject to future refinement when the clinical experience in head-and-neck IMRT advances

  5. Poster - Thur Eve - 13: Quantifying specific absorption rate of shielded RF coils through electromagnetic simulations for 7-T MRI.

    Science.gov (United States)

    Belliveau, J-G; Gilbert, K M; Abou-Khousa, M; Menon, R S

    2012-07-01

    Ultra-high field MRI has many advantages such as increasing spatial resolution and exploiting contrast never before seen in-vivo. This contrast has been shown to be beneficial for many applications such as monitoring early and late effect to radiation therapy and transient changes during disease to name a few. However, at higher field strengths the RF wave, needed to for transmitting and receiving signal, approaches that of the head. This leads to constructive and deconstructive interference and a non -uniform flip angle over the volume being imaged. A transmit or transceive RF surface coil arrays is currently a method of choice to overcome this problem; however, mutual inductance between elements poses a significant challenge for the designer. A method to decouple elements in such an array is by using circumferential shielding; however, the potential benefits and/or disadvantages have not been investigated. This abstract primarily focuses on understanding power deposition - measured through Specific Absorption Rate - in the sample using circumferentially shielded RF coils. Various geometries of circumferentially shielded coils are explored to determine the behaviour of shield width and its effect on required transmit power and power deposition to the sample. Our results indicate that there is an optimization on shield width depending on the imaging depth. Additionally, the circumferential shield focuses the field more than unshielded coils, meaning that slight SAR may even be lower for circumferential shielded RF coils in array. © 2012 American Association of Physicists in Medicine.

  6. Implications of improved diagnostic imaging of small nodal metastases in head and neck cancer: Radiotherapy target volume transformation and dose de-escalation.

    Science.gov (United States)

    van den Bosch, Sven; Vogel, Wouter V; Raaijmakers, Cornelis P; Dijkema, Tim; Terhaard, Chris H J; Al-Mamgani, Abrahim; Kaanders, Johannes H A M

    2018-05-03

    Diagnostic imaging continues to evolve, and now has unprecedented accuracy for detecting small nodal metastasis. This influences the tumor load in elective target volumes and subsequently has consequences for the radiotherapy dose required to control disease in these volumes. Small metastases that used to remain subclinical and were included in elective volumes, will nowadays be detected and included in high-dose volumes. Consequentially, high-dose volumes will more often contain low-volume disease. These target volume transformations lead to changes in the tumor burden in elective and "gross" tumor volumes with implications for the radiotherapy dose prescribed to these volumes. For head and neck tumors, nodal staging has evolved from mere palpation to combinations of high-resolution imaging modalities. A traditional nodal gross tumor volume in the neck typically had a minimum diameter of 10-15 mm, while nowadays much smaller tumor deposits are detected in lymph nodes. However, the current dose levels for elective nodal irradiation were empirically determined in the 1950s, and have not changed since. In this report the radiobiological consequences of target volume transformation caused by modern imaging of the neck are evaluated, and theoretically derived reductions of dose in radiotherapy for head and neck cancer are proposed. The concept of target volume transformation and subsequent strategies for dose adaptation applies to many other tumor types as well. Awareness of this concept may result in new strategies for target definition and selection of dose levels with the aim to provide optimal tumor control with less toxicity. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  7. Numerical dosimetry of transcranial magnetic stimulation coils

    Science.gov (United States)

    Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2014-03-01

    Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique capable of stimulating neurons by means of electromagnetic induction. TMS can be used to map brain function and shows promise for the diagnosis and treatment of neurological and psychiatric disorders. Calculation of fields induced in the brain are necessary to accurately identify stimulated neural tissue during TMS. This allows the development of novel TMS coil designs capable of stimulating deeper brain regions and increasing the localization of stimulation that can be achieved. We have performed numerical calculations of magnetic and electric field with high-resolution anatomically realistic human head models to find these stimulated brain regions for a variety of proposed TMS coil designs. The realistic head models contain heterogeneous tissue structures and electrical conductivities, yielding superior results to those obtained from the simplified homogeneous head models that are commonly employed. The attenuation of electric field as a function of depth in the brain and the localization of stimulating field have been methodically investigated. In addition to providing a quantitative comparison of different TMS coil designs the variation of induced field between subjects has been investigated. We also show the differences in induced fields between adult, adolescent and child head models to preemptively identify potential safety issues in the application of pediatric TMS.

  8. Single coil bistable, bidirectional micromechanical actuator

    Science.gov (United States)

    Tabat, Ned; Guckel, Henry

    1998-09-15

    Micromechanical actuators capable of bidirectional and bistable operation can be formed on substrates using lithographic processing techniques. Bistable operation of the microactuator is obtained using a single coil and a magnetic core with a gap. A plunger having two magnetic heads is supported for back and forth linear movement with respect to the gap in the magnetic core, and is spring biased to a neutral position in which the two heads are on each side of the gap in the core. The single electrical coil is coupled to the core and is provided with electrical current to attract one of the heads toward the core by reluctance action to drive the plunger to a limit of travel in one direction. The current is then cut off and the plunger returns by spring action toward the gap, whereafter the current is reapplied to the coil to attract the other head of the plunger by reluctance action to drive the plunger to its other limit of travel. This process can be repeated at a time when switching of the actuator is required.

  9. Can FDG-PET assist in radiotherapy target volume definition of metastatic lymph nodes in head-and-neck cancer?

    International Nuclear Information System (INIS)

    Schinagl, Dominic A.X.; Hoffmann, Aswin L.; Vogel, Wouter V.; Dalen, Jorn A. van; Verstappen, Suzan M.M.; Oyen, Wim J.G.; Kaanders, Johannes H.A.M.

    2009-01-01

    Background and purpose: The role of FDG-PET in radiotherapy target volume definition of the neck was evaluated by comparing eight methods of FDG-PET segmentation to the current CT-based practice of lymph node assessment in head-and-neck cancer patients. Materials and methods: Seventy-eight head-and-neck cancer patients underwent coregistered CT- and FDG-PET scans. Lymph nodes were classified as 'enlarged' if the shortest axial diameter on CT was ≥10 mm, and as 'marginally enlarged' if it was 7-10 mm. Subsequently, lymph nodes were assessed on FDG-PET applying eight segmentation methods: visual interpretation (PET VIS ), applying fixed thresholds at a standardized uptake value (SUV) of 2.5 and at 40% and 50% of the maximum signal intensity of the primary tumor (PET SUV , PET 40% , PET 50% ) and applying a variable threshold based on the signal-to-background ratio (PET SBR ). Finally, PET 40%N , PET 50%N and PET SBRN were acquired using the signal of the lymph node as the threshold reference. Results: Of 108 nodes classified as 'enlarged' on CT, 75% were also identified by PET VIS , 59% by PET 40% , 43% by PET 50% and 43% by PET SBR . Of 100 nodes classified as 'marginally enlarged', only a minority were visualized by FDG-PET. The respective numbers were 26%, 10%, 7% and 8% for PET VIS , PET 40% , PET 50% and PET SBR . PET 40%N , PET 50%N and PET SBRN , respectively, identified 66%, 82% and 96% of the PET VIS -positive nodes. Conclusions: Many lymph nodes that are enlarged and considered metastatic by standard CT-based criteria appear to be negative on FDG-PET scan. Alternately, a small proportion of marginally enlarged nodes are positive on FDG-PET scan. However, the results are largely dependent on the PET segmentation tool used, and until proper validation FDG-PET is not recommended for target volume definition of metastatic lymph nodes in routine practice.

  10. Active internal corrector coils

    International Nuclear Information System (INIS)

    Thompson, P.A.; Cottingham, J.; Dahl, P.

    1986-01-01

    Trim or corrector coils to correct main magnet field errors and provide higher multipole fields for beam optics purposes are a standard feature of superconducting magnet accelerator systems. This paper describes some of the design and construction features of powered internal trim coils and a sampling of the test results obtained

  11. Compact stellarator coils

    International Nuclear Information System (INIS)

    Pomphrey, N.; Berry, L.A.; Boozer, A.H.

    2001-01-01

    Experimental devices to study the physics of high-beta (β>∼4%), low aspect ratio (A<∼4.5) stellarator plasmas require coils that will produce plasmas satisfying a set of physics goals, provide experimental flexibility, and be practical to construct. In the course of designing a flexible coil set for the National Compact Stellarator Experiment, we have made several innovations that may be useful in future stellarator design efforts. These include: the use of Singular Value Decomposition methods for obtaining families of smooth current potentials on distant coil winding surfaces from which low current density solutions may be identified; the use of a Control Matrix Method for identifying which few of the many detailed elements of the stellarator boundary must be targeted if a coil set is to provide fields to control the essential physics of the plasma; the use of Genetic Algorithms for choosing an optimal set of discrete coils from a continuum of potential contours; the evaluation of alternate coil topologies for balancing the tradeoff between physics objective and engineering constraints; the development of a new coil optimization code for designing modular coils, and the identification of a 'natural' basis for describing current sheet distributions. (author)

  12. Liquid rope coiling

    NARCIS (Netherlands)

    Ribe, N.M.; Habibi, M.; Bonn, D.

    2012-01-01

    A thin stream or rope of viscous fluid falling from a sufficient height onto a surface forms a steadily rotating helical coil. Tabletop laboratory experiments in combination with a numerical model for slender liquid ropes reveal that finite-amplitude coiling can occur in four distinct regimes

  13. Automatic skull segmentation from MR images for realistic volume conductor models of the head: Assessment of the state-of-the-art

    DEFF Research Database (Denmark)

    Nielsen, Jesper Duemose; Madsen, Kristoffer Hougaard; Puonti, Oula

    2018-01-01

    Anatomically realistic volume conductor models of the human head are important for accurate forward modeling of the electric field during transcranial brain stimulation (TBS), electro- (EEG) and magnetoencephalography (MEG). In particular, the skull compartment exerts a strong influence on the fi......Anatomically realistic volume conductor models of the human head are important for accurate forward modeling of the electric field during transcranial brain stimulation (TBS), electro- (EEG) and magnetoencephalography (MEG). In particular, the skull compartment exerts a strong influence...... local defects. In contrast to FSL BET2, the SPM12-based segmentation with extended spatial tissue priors and the BrainSuite-based segmentation provide coarse reconstructions of the vertebrae, enabling the construction of volume conductor models that include the neck. We exemplarily demonstrate...

  14. Micro- and nano-volume samples by electrothermal, near-torch vaporization sample introduction using removable, interchangeable and portable rhenium coiled-filament assemblies and axially-viewed inductively coupled plasma-atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Badiei, Hamid R.; Lai, Bryant; Karanassios, Vassili

    2012-11-15

    An electrothermal, near-torch vaporization (NTV) sample introduction for micro- or nano-volume samples is described. Samples were pipetted onto coiled-filament assemblies that were purposely developed to be removable and interchangeable and were dried and vaporized into a small-volume vaporization chamber that clips onto any ICP torch with a ball joint. Interchangeable assemblies were also constructed to be small-size (e.g., less than 3 cm long with max diameter of 0.65 cm) and light-weight (1.4 g) so that they can be portable. Interchangeable assemblies with volume-capacities in three ranges (i.e., < 1 {mu}L, 1-10 {mu}L and 10-100 {mu}L) were fabricated and used. The horizontally-operated NTV sample introduction was interfaced to an axially-viewed ICP-AES (inductively coupled plasma-atomic emission spectrometry) system and NTV was optimized using ICP-AES and 8 elements (Pb, Cd, Zn, V, Ba, Mg, Be and Ca). Precision was 1.0-2.3% (peak height) and 1.1-2.4% (peak area). Detection limits (obtained using 5 {mu}L volumes) expressed in absolute-amounts ranged between 4 pg for Pb to 0.3 fg ({approx} 5 million atoms) for Ca. Detection limits expressed in concentration units (obtained using 100 {mu}L volumes of diluted, single-element standard solutions) were: 50 pg/mL for Pb; 10 pg/mL for Cd; 9 pg/mL for Zn; 1 pg/mL for V; 0.9 pg/mL for Ba; 0.5 pg/mL for Mg; 50 fg/mL for Be; and 3 fg/mL for Ca. Analytical capability and utility was demonstrated using the determination of Pb in pg/mL levels of diluted natural water Certified Reference Material (CRM) and the determination of Zn in 80 nL volumes of the liquid extracted from an individual vesicle. It is shown that portable and interchangeable assemblies with dried sample residues on them can be transported without analyte loss (for the concentrations tested), thus opening up the possibility for 'taking part of the lab to the sample' applications, such as testing for Cu concentration-compliance with the lead

  15. Molecular basis of coiled-coil oligomerization-state specificity.

    Science.gov (United States)

    Ciani, Barbara; Bjelic, Saša; Honnappa, Srinivas; Jawhari, Hatim; Jaussi, Rolf; Payapilly, Aishwarya; Jowitt, Thomas; Steinmetz, Michel O; Kammerer, Richard A

    2010-11-16

    Coiled coils are extensively and successfully used nowadays to rationally design multistranded structures for applications, including basic research, biotechnology, nanotechnology, materials science, and medicine. The wide range of applications as well as the important functions these structures play in almost all biological processes highlight the need for a detailed understanding of the factors that control coiled-coil folding and oligomerization. Here, we address the important and unresolved question why the presence of particular oligomerization-state determinants within a coiled coil does frequently not correlate with its topology. We found an unexpected, general link between coiled-coil oligomerization-state specificity and trigger sequences, elements that are indispensable for coiled-coil formation. By using the archetype coiled-coil domain of the yeast transcriptional activator GCN4 as a model system, we show that well-established trimer-specific oligomerization-state determinants switch the peptide's topology from a dimer to a trimer only when inserted into the trigger sequence. We successfully confirmed our results in two other, unrelated coiled-coil dimers, ATF1 and cortexillin-1. We furthermore show that multiple topology determinants can coexist in the same trigger sequence, revealing a delicate balance of the resulting oligomerization state by position-dependent forces. Our experimental results should significantly improve the prediction of the oligomerization state of coiled coils. They therefore should have major implications for the rational design of coiled coils and consequently many applications using these popular oligomerization domains.

  16. Coiled transmission line pulse generators

    Science.gov (United States)

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  17. Pathology-based validation of FDG PET segmentation tools for volume assessment of lymph node metastases from head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Schinagl, Dominic A.X. [Radboud University Nijmegen Medical Centre, Department of Radiation Oncology, Nijmegen (Netherlands); Radboud University Nijmegen Medical Centre, Department of Radiation Oncology (874), P.O. Box 9101, Nijmegen (Netherlands); Span, Paul N.; Kaanders, Johannes H.A.M. [Radboud University Nijmegen Medical Centre, Department of Radiation Oncology, Nijmegen (Netherlands); Hoogen, Frank J.A. van den [Radboud University Nijmegen Medical Centre, Department of Otorhinolaryngology, Head and Neck Surgery, Nijmegen (Netherlands); Merkx, Matthias A.W. [Radboud University Nijmegen Medical Centre, Department of Oral and Maxillofacial Surgery, Nijmegen (Netherlands); Slootweg, Piet J. [Radboud University Nijmegen Medical Centre, Department of Pathology, Nijmegen (Netherlands); Oyen, Wim J.G. [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, Nijmegen (Netherlands)

    2013-12-15

    FDG PET is increasingly incorporated into radiation treatment planning of head and neck cancer. However, there are only limited data on the accuracy of radiotherapy target volume delineation by FDG PET. The purpose of this study was to validate FDG PET segmentation tools for volume assessment of lymph node metastases from head and neck cancer against the pathological method as the standard. Twelve patients with head and neck cancer and 28 metastatic lymph nodes eligible for therapeutic neck dissection underwent preoperative FDG PET/CT. The metastatic lymph nodes were delineated on CT (Node{sub CT}) and ten PET segmentation tools were used to assess FDG PET-based nodal volumes: interpreting FDG PET visually (PET{sub VIS}), applying an isocontour at a standardized uptake value (SUV) of 2.5 (PET{sub SUV}), two segmentation tools with a fixed threshold of 40 % and 50 %, and two adaptive threshold based methods. The latter four tools were applied with the primary tumour as reference and also with the lymph node itself as reference. Nodal volumes were compared with the true volume as determined by pathological examination. Both Node{sub CT} and PET{sub VIS} showed good correlations with the pathological volume. PET segmentation tools using the metastatic node as reference all performed well but not better than PET{sub VIS}. The tools using the primary tumour as reference correlated poorly with pathology. PET{sub SUV} was unsatisfactory in 35 % of the patients due to merging of the contours of adjacent nodes. FDG PET accurately estimates metastatic lymph node volume, but beyond the detection of lymph node metastases (staging), it has no added value over CT alone for the delineation of routine radiotherapy target volumes. If FDG PET is used in radiotherapy planning, treatment adaptation or response assessment, we recommend an automated segmentation method for purposes of reproducibility and interinstitutional comparison. (orig.)

  18. Structural mapping of the coiled-coil domain of a bacterial condensin and comparative analyses across all domains of life suggest conserved features of SMC proteins.

    Science.gov (United States)

    Waldman, Vincent M; Stanage, Tyler H; Mims, Alexandra; Norden, Ian S; Oakley, Martha G

    2015-06-01

    The structural maintenance of chromosomes (SMC) proteins form the cores of multisubunit complexes that are required for the segregation and global organization of chromosomes in all domains of life. These proteins share a common domain structure in which N- and C- terminal regions pack against one another to form a globular ATPase domain. This "head" domain is connected to a central, globular, "hinge" or dimerization domain by a long, antiparallel coiled coil. To date, most efforts for structural characterization of SMC proteins have focused on the globular domains. Recently, however, we developed a method to map interstrand interactions in the 50-nm coiled-coil domain of MukB, the divergent SMC protein found in γ-proteobacteria. Here, we apply that technique to map the structure of the Bacillus subtilis SMC (BsSMC) coiled-coil domain. We find that, in contrast to the relatively complicated coiled-coil domain of MukB, the BsSMC domain is nearly continuous, with only two detectable coiled-coil interruptions. Near the middle of the domain is a break in coiled-coil structure in which there are three more residues on the C-terminal strand than on the N-terminal strand. Close to the head domain, there is a second break with a significantly longer insertion on the same strand. These results provide an experience base that allows an informed interpretation of the output of coiled-coil prediction algorithms for this family of proteins. A comparison of such predictions suggests that these coiled-coil deviations are highly conserved across SMC types in a wide variety of organisms, including humans. © 2015 Wiley Periodicals, Inc.

  19. 3-D segmentation of retinal blood vessels in spectral-domain OCT volumes of the optic nerve head

    Science.gov (United States)

    Lee, Kyungmoo; Abràmoff, Michael D.; Niemeijer, Meindert; Garvin, Mona K.; Sonka, Milan

    2010-03-01

    Segmentation of retinal blood vessels can provide important information for detecting and tracking retinal vascular diseases including diabetic retinopathy, arterial hypertension, arteriosclerosis and retinopathy of prematurity (ROP). Many studies on 2-D segmentation of retinal blood vessels from a variety of medical images have been performed. However, 3-D segmentation of retinal blood vessels from spectral-domain optical coherence tomography (OCT) volumes, which is capable of providing geometrically accurate vessel models, to the best of our knowledge, has not been previously studied. The purpose of this study is to develop and evaluate a method that can automatically detect 3-D retinal blood vessels from spectral-domain OCT scans centered on the optic nerve head (ONH). The proposed method utilized a fast multiscale 3-D graph search to segment retinal surfaces as well as a triangular mesh-based 3-D graph search to detect retinal blood vessels. An experiment on 30 ONH-centered OCT scans (15 right eye scans and 15 left eye scans) from 15 subjects was performed, and the mean unsigned error in 3-D of the computer segmentations compared with the independent standard obtained from a retinal specialist was 3.4 +/- 2.5 voxels (0.10 +/- 0.07 mm).

  20. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

    Science.gov (United States)

    Anderson, Danielle; Siegbahn, E. Albert; Fallone, B. Gino; Serduc, Raphael; Warkentin, Brad

    2012-05-01

    This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm2 microbeam array in each phantom, as well as a 16 × 16 mm2 array in the 8 cm cat head, and a 32 × 32 mm2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2-49 (mouse) and 2-46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2-87% and 33-96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this study

  1. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

    International Nuclear Information System (INIS)

    Anderson, Danielle; Fallone, B Gino; Warkentin, Brad; Siegbahn, E Albert; Serduc, Raphael

    2012-01-01

    This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm 2 microbeam array in each phantom, as well as a 16 × 16 mm 2 array in the 8 cm cat head, and a 32 × 32 mm 2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2–49 (mouse) and 2–46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2–87% and 33–96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this

  2. Primary Tumor Volume Is an Important Predictor of Clinical Outcomes Among Patients With Locally Advanced Squamous Cell Cancer of the Head and Neck Treated With Definitive Chemoradiotherapy

    International Nuclear Information System (INIS)

    Strongin, Anna; Yovino, Susannah; Taylor, Rodney; Wolf, Jeffrey; Cullen, Kevin; Zimrin, Ann; Strome, Scott; Regine, William; Suntharalingam, Mohan

    2012-01-01

    Purpose: The tumor volume has been established as a significant predictor of outcomes among patients with head-and-neck cancer undergoing radiotherapy alone. The present study attempted to add to the existing data on tumor volume as a prognostic factor among patients undergoing chemoradiotherapy. Methods and Materials: A total of 78 patients who had undergone definitive chemoradiotherapy for Stage III-IV squamous cell cancer of the hypopharynx, oropharynx, and larynx were identified. The primary tumor volumes were calculated from the treatment planning computed tomography scans, and these were correlated to the survival and tumor control data obtained from the retrospective analysis. Results: The interval to progression correlated with the primary tumor volume (p = .007). The critical cutoff point for the tumor volume was identified as 35 cm 3 , and patients with a tumor volume 3 had a significantly better prognosis than those with a tumor volume >35 cm 3 at 5 years (43% vs. 71%, p = .010). Longer survival was also correlated with smaller primary tumor volumes (p = .022). Similarly, patients with a primary tumor volume 3 had a better prognosis in terms of both progression-free survival (61% vs. 33%, p = .004) and overall survival (84% vs. 41%, p = 3 larger than tumors without locoregional failure (p = .028) and 27.1-cm 3 larger than tumors that recurred as distant metastases (p = .020). Conclusion: The results of our study have shown that the primary tumor volume is a significant prognostic factor in patients with advanced cancer of the head and neck undergoing definitive chemoradiotherapy and correlated with the treatment outcomes better than the T or N stage.

  3. Weekly Volume and Dosimetric Changes During Chemoradiotherapy With Intensity-Modulated Radiation Therapy for Head and Neck Cancer: A Prospective Observational Study

    Energy Technology Data Exchange (ETDEWEB)

    Bhide, Shreerang A [Institute of Cancer Research, 237 Fulham Road, London SW6 6JB (United Kingdom); Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom); Davies, Mark; Burke, Kevin; McNair, Helen A; Hansen, Vibeke [Department of Radiation Oncology, Royal Marsden NHS Foundation Trust Hospital, London and Sutton (United Kingdom); Barbachano, Y [Department of Statistics, Royal Marsden NHS Foundation Trust Hospital, London and Sutton (United Kingdom); El-Hariry, I A [Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom); Newbold, Kate [Department of Radiation Oncology, Royal Marsden NHS Foundation Trust Hospital, London and Sutton (United Kingdom); Harrington, Kevin J [Institute of Cancer Research, 237 Fulham Road, London SW6 6JB (United Kingdom); Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom); Nutting, Christopher M., E-mail: chris.nutting@rmh.nhs.u [Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom)

    2010-04-15

    Purpose: The aim of this study was to investigate prospectively the weekly volume changes in the target volumes and organs at risk and the resulting dosimetric changes during induction chemotherapy followed by chemoradiotherapy with intensity-modulated radiation therapy (C-IMRT) for head-and-neck cancer patients. Methods and Materials: Patients receiving C-IMRT for head-and-neck cancer had repeat CT scans at weeks 2, 3, 4, and 5 during radiotherapy. The volume changes of clinical target volume 1 (CTV1) and CTV2 and the resulting dosimetric changes to planning target volume 1 (PTV1) and PTV2 and the organs at risk were measured. Results: The most significant volume differences were seen at week 2 for CTV1 and CTV2. The reductions in the volumes of CTV1 and CTV2 at week 2 were 3.2% and 10%, respectively (p = 0.003 and p < 0.001). The volume changes resulted in a significant reduction in the minimum dose to PTV1 and PTV2 (2 Gy, p = 0.002, and 3.9 Gy, p = 0.03, respectively) and an increased dose range across PTV1 and PTV2 (2.5 Gy, p < 0.001, and 5.1 Gy, p = 0.008, respectively). There was a 15% reduction in the parotid volumes by week 2 (p < 0.001) and 31% by week 4 (p < 0.001). There was a statistically significant increase in the mean dose to the ipsilateral parotid only at week 4 (2.7 Gy, p = 0.006). The parotid glands shifted medially by an average of 2.3 mm (p < 0.001) by week 4. Conclusion: The most significant volumetric changes and dosimetric alterations in the tumor volumes and organs at risk during a course of C-IMRT occur by week 2 of radiotherapy. Further adaptive radiotherapy with replanning, if appropriate, is recommended.

  4. Large coil task and results of testing US coils

    International Nuclear Information System (INIS)

    Haubenreich, P.N.

    1986-01-01

    The United States, EURATOM, Japan, and Switzerland have collaborated since 1978 in development of superconducting toroidal field coils for fusion reactor applications. The United States provided a test facility nd three coils; the other participants, one coil each. All coils have the same interface dimensions and performance requirements (stable at 8 T), but internal design was decided by each team. Two US coil teams chose bath-cooled NbTi, 10-kA conductors. One developed a Nb 3 Sn conductor, cooled by internal flow, rated at 18 kA. All US coils have diagnostic instrumentation and imbedded heaters that enable stability tests and simulated nuclear heating experiments. In single-coil tests, each coil operated at full current in self-field (6.4 T). In six-coil tests that began in July 1986, one US coil and the Japanese coil hve been successfully operated at full current at 8 T. The other coils have operated as background coils while awaiting their turn as test coil. Coil tests have been informative and results gratifying. The facility has capably supported coil testing and its operation has provided information that will be useful in designing future fusion systems. Coil capabilities beyond nominal design points will be determined

  5. Design of superconducting toroidal magnet coils and testing facility in the USA

    International Nuclear Information System (INIS)

    Luton, J.N.; Haubenreich, P.N.; Thompson, P.B.

    1977-01-01

    In the U.S. Large Coil Program, three industrial teams are presently designing test coils to general specifications prepared by the Oak Ridge National Laboratory with guidance from USERDA. Each test coil is approximately half the bore size of reactor coils, being oval or D-shaped, with a bore of 2.5 x 3.5 m. The dimensions and operating requirements of the coils are identical for all test coils. The coils are designed to produce a peak field of at least 8 tesla at the winding of a selected coil operated at its design current. This condition is met when the selected coil is operated in a compact toroidal array of 6 coils, with the other five coils being operated at 0.8 of their design current. The six coils are of three different designs. Both pool boiling and forced flow designs are included. The coils are housed in a single large vacuum chamber for economy and testing convenience. Auxiliary coils provide a pulse field over the test coil winding volume. This auxiliary system is designed to produce a pulse field which rises to a peak of 0.14 T in 1 sec. With the exception of material damage due to neutron irradiation, all reactor requirements and environments will be either duplicated, approximated, or simulated. The test facility is being designed to accept coils producing up to 12 tesla in later phases of the program

  6. Commercial applications for COIL

    Science.gov (United States)

    Solomon, Wayne C.; Carroll, David L.; King, D. M.; Fockler, L. A.; Stromberg, D. S.; Sexauer, M.; Milmoe, A.; Sentman, Lee H.

    2000-01-01

    The chemical oxygen-iodine laser (COIL) is a high power, fiber deliverable tool, which can be used for a number of different industrial applications. COIL is of particular interest because of its short fiber deliverable wavelength, high scaleable continuous wave power, and excellent material interaction properties. In past research the University of Illinois at Urbana-Champaign identified and decommissioning and decontamination (DD) of nuclear facilities as a primary focus for COIL technology. DD will be a major challenge in the coming decades. The use of a robotically driven fiber delivered cutting/ablation tool in contaminated areas promises to lower risks to workers for the DD mission. Further, the high cutting speed of COIL will significantly reduce the time required to cut contaminated equipment, reducing costs. The high power of COIL will permit the dismantling of thick stacks of piping and equipment as well as reactor vessels. COIL is very promising for the removal of material from contaminated surfaces, perhaps to depths thicker than an inch. Laser cutting and ablation minimizes dust and fumes, which reduces the required number of high efficiency particulate accumulator filters, thus reducing costly waste disposal. Other potential industrial applications for COIL are shipbuilding, automotive manufacturing, heavy machinery manufacturing, tasks requiring underwater cutting or welding, and there appear to be very promising applications for high powers lasers in the oil industry.

  7. Open coil traction system.

    Science.gov (United States)

    Vibhute, Pavankumar Janardan

    2012-01-01

    Sliding mechanics have become a popular method for space closure, with the development of preadjusted edgewise appliances. Furthermore, various space closing auxiliaries have been developed and extensively evaluated for their clinical efficiency. Their effectiveness is enhanced with optimum force magnitude and low load deflection rate/force decay. With the advent of nickel-titanium (Ni-Ti) springs in orthodontics, load deflection rates have been markedly reduced. To use Ni-Ti springs, clinicians have to depend upon prefabricated closed coil springs. The open coil traction system, or open coil retraction spring, is developed utilizing Ni-Ti open coil springs for orthodontic space closure. This article describes the fabrication and clinical application of the open coil traction system, which has a number of advantages. It sustains a low load deflection rate with optimum force magnitude, and its design is adjustable for a desired length and force level. It is fail-safe for both activation and deactivation (ie, it cannot be overactivated, and the decompression limit of the open coil is controlled by the operator). The open coil traction system can be offset from the mucosa to help reduce soft tissue impingement.

  8. Comparison of five segmentation tools for 18F-fluoro-deoxy-glucose-positron emission tomography-based target volume definition in head and neck cancer.

    Science.gov (United States)

    Schinagl, Dominic A X; Vogel, Wouter V; Hoffmann, Aswin L; van Dalen, Jorn A; Oyen, Wim J; Kaanders, Johannes H A M

    2007-11-15

    Target-volume delineation for radiation treatment to the head and neck area traditionally is based on physical examination, computed tomography (CT), and magnetic resonance imaging. Additional molecular imaging with (18)F-fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) may improve definition of the gross tumor volume (GTV). In this study, five methods for tumor delineation on FDG-PET are compared with CT-based delineation. Seventy-eight patients with Stages II-IV squamous cell carcinoma of the head and neck area underwent coregistered CT and FDG-PET. The primary tumor was delineated on CT, and five PET-based GTVs were obtained: visual interpretation, applying an isocontour of a standardized uptake value of 2.5, using a fixed threshold of 40% and 50% of the maximum signal intensity, and applying an adaptive threshold based on the signal-to-background ratio. Absolute GTV volumes were compared, and overlap analyses were performed. The GTV method of applying an isocontour of a standardized uptake value of 2.5 failed to provide successful delineation in 45% of cases. For the other PET delineation methods, volume and shape of the GTV were influenced heavily by the choice of segmentation tool. On average, all threshold-based PET-GTVs were smaller than on CT. Nevertheless, PET frequently detected significant tumor extension outside the GTV delineated on CT (15-34% of PET volume). The choice of segmentation tool for target-volume definition of head and neck cancer based on FDG-PET images is not trivial because it influences both volume and shape of the resulting GTV. With adequate delineation, PET may add significantly to CT- and physical examination-based GTV definition.

  9. Comparison of Five Segmentation Tools for 18F-Fluoro-Deoxy-Glucose-Positron Emission Tomography-Based Target Volume Definition in Head and Neck Cancer

    International Nuclear Information System (INIS)

    Schinagl, Dominic A.X.; Vogel, Wouter V.; Hoffmann, Aswin L.; Dalen, Jorn A. van; Oyen, Wim J.; Kaanders, Johannes H.A.M.

    2007-01-01

    Purpose: Target-volume delineation for radiation treatment to the head and neck area traditionally is based on physical examination, computed tomography (CT), and magnetic resonance imaging. Additional molecular imaging with 18 F-fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) may improve definition of the gross tumor volume (GTV). In this study, five methods for tumor delineation on FDG-PET are compared with CT-based delineation. Methods and Materials: Seventy-eight patients with Stages II-IV squamous cell carcinoma of the head and neck area underwent coregistered CT and FDG-PET. The primary tumor was delineated on CT, and five PET-based GTVs were obtained: visual interpretation, applying an isocontour of a standardized uptake value of 2.5, using a fixed threshold of 40% and 50% of the maximum signal intensity, and applying an adaptive threshold based on the signal-to-background ratio. Absolute GTV volumes were compared, and overlap analyses were performed. Results: The GTV method of applying an isocontour of a standardized uptake value of 2.5 failed to provide successful delineation in 45% of cases. For the other PET delineation methods, volume and shape of the GTV were influenced heavily by the choice of segmentation tool. On average, all threshold-based PET-GTVs were smaller than on CT. Nevertheless, PET frequently detected significant tumor extension outside the GTV delineated on CT (15-34% of PET volume). Conclusions: The choice of segmentation tool for target-volume definition of head and neck cancer based on FDG-PET images is not trivial because it influences both volume and shape of the resulting GTV. With adequate delineation, PET may add significantly to CT- and physical examination-based GTV definition

  10. Determining optimal clinical target volume margins in head-and-neck cancer based on microscopic extracapsular extension of metastatic neck nodes

    International Nuclear Information System (INIS)

    Apisarnthanarax, Smith; Elliott, Danielle D.; El-Naggar, Adel K.; Asper, Joshua A. P.A.; Blanco, Angel; Ang, K. Kian; Garden, Adam S.; Morrison, William H.; Rosenthal, David; Weber, Randal S.; Chao, K.S. Clifford

    2006-01-01

    Purpose: To determine the optimal clinical target volume margins around the gross nodal tumor volume in head-and-neck cancer by assessing microscopic tumor extension beyond cervical lymph node capsules. Methods and Materials: Histologic sections of 96 dissected cervical lymph nodes with extracapsular extension (ECE) from 48 patients with head-and-neck squamous cell carcinoma were examined. The maximum linear distance from the external capsule border to the farthest extent of the tumor or tumoral reaction was measured. The trends of ECE as a function of the distance from the capsule and lymph node size were analyzed. Results: The median diameter of all lymph nodes was 11.0 mm (range: 3.0-30.0 mm). The mean and median ECE extent was 2.2 mm and 1.6 mm, respectively (range: 0.4-9.0 mm). The ECE was <5 mm from the capsule in 96% of the nodes. As the distance from the capsule increased, the probability of tumor extension declined. No significant difference between the extent of ECE and lymph node size was observed. Conclusion: For N1 nodes that are at high risk for ECE but not grossly infiltrating musculature, 1 cm clinical target volume margins around the nodal gross tumor volume are recommended to cover microscopic nodal extension in head-and-neck cancer

  11. Extrap with iron-cored coils

    International Nuclear Information System (INIS)

    Lehnert, B.

    1985-05-01

    In Extrap configurations there is a high average beta value with respect to the plasma confinement volume. The externally imposed magnetic field which is required for stabilization therefore comes out to have a rather moderate strength, even under expected reactor conditions. As a consequence, this field can be generated not only by conventional external conductor arrangements, but also by iron-cored coils being operated below the saturation limit. A proposal for such iron-cored coil systems is presented in this paper. As compared to conventional conductors, this has the advantage of localizing the magnetic energy of the externally imposed magnetic field mainly to the discharge vessel and the plasma volume, thereby increasing the engineering beta value substantially. Also the problems of the coil stresses and of irradiation of the coils appear to become simplified, as well as replacement of the coil system. A main limitation of this proposal is due to combination of iron core saturation with the required stabilization effect from an ion Larmor radius of sufficient relative magnitude. This limitaion requires further investigation, especially in the full-scale reactor case. Also the modifications of the field geometry by iron core shaping needs further analysis. (Author)

  12. Coil spring venting arrangement

    International Nuclear Information System (INIS)

    McCugh, R.M.

    1975-01-01

    A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed

  13. Extending the self-assembly of coiled-coil hybrids

    NARCIS (Netherlands)

    Robson Marsden, Hana

    2009-01-01

    Of the various biomolecular building blocks in use in nature, coiled-coil forming peptides are amongst those with the most potential as building blocks for the synthetic self-assembly of nanostructures. Native coiled coils have the ability to function in, and influence, complex systems composed of

  14. A periodic table of coiled-coil protein structures.

    Science.gov (United States)

    Moutevelis, Efrosini; Woolfson, Derek N

    2009-01-23

    Coiled coils are protein structure domains with two or more alpha-helices packed together via interlacing of side chains known as knob-into-hole packing. We analysed and classified a large set of coiled-coil structures using a combination of automated and manual methods. This led to a systematic classification that we termed a "periodic table of coiled coils," which we have made available at http://coiledcoils.chm.bris.ac.uk/ccplus/search/periodic_table. In this table, coiled-coil assemblies are arranged in columns with increasing numbers of alpha-helices and in rows of increased complexity. The table provides a framework for understanding possibilities in and limits on coiled-coil structures and a basis for future prediction, engineering and design studies.

  15. LHC bending magnet coil

    CERN Multimedia

    A short test version of coil of wire used for the LHC dipole magnets. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9’000 niobium–titanium filaments ten times finer than a hair.

  16. Borehole induction coil transmitter

    Science.gov (United States)

    Holladay, Gale; Wilt, Michael J.

    2002-01-01

    A borehole induction coil transmitter which is a part of a cross-borehole electromagnetic field system that is used for underground imaging applications. The transmitter consists of four major parts: 1) a wound ferrite or mu-metal core, 2) an array of tuning capacitors, 3) a current driver circuit board, and 4) a flux monitor. The core is wound with several hundred turns of wire and connected in series with the capacitor array, to produce a tuned coil. This tuned coil uses internal circuitry to generate sinusoidal signals that are transmitted through the earth to a receiver coil in another borehole. The transmitter can operate at frequencies from 1-200 kHz and supplies sufficient power to permit the field system to operate in boreholes separated by up to 400 meters.

  17. Differential Search Coils Based Magnetometers: Conditioning, Magnetic Sensitivity, Spatial Resolution

    Directory of Open Access Journals (Sweden)

    Timofeeva Maria

    2012-03-01

    Full Text Available A theoretical and experimental comparison of optimized search coils based magnetometers, operating either in the Flux mode or in the classical Lenz-Faraday mode, is presented. The improvements provided by the Flux mode in terms of bandwidth and measuring range of the sensor are detailed. Theory, SPICE model and measurements are in good agreement. The spatial resolution of the sensor is studied which is an important parameter for applications in non destructive evaluation. A general expression of the magnetic sensitivity of search coils sensors is derived. Solutions are proposed to design magnetometers with reduced weight and volume without degrading the magnetic sensitivity. An original differential search coil based magnetometer, made of coupled coils, operating in flux mode and connected to a differential transimpedance amplifier is proposed. It is shown that this structure is better in terms of volume occupancy than magnetometers using two separated coils without any degradation in magnetic sensitivity. Experimental results are in good agreement with calculations.

  18. On modular stellarator reactor coils

    International Nuclear Information System (INIS)

    Rau, F.; Harmeyer, E.; Kisslinger, J.; Wobig, H.

    1985-01-01

    Modular twisted coils are discussed which produce magnetic fields of the Advanced Stellarator WENDELSTEIN VII-AS type. Reducing the number coils/FP offers advantage for maintenance of coils, but increases the magnetic ripple and B m /B o . Computation of force densities within the coils of ASR and ASB yield local maximum values of about 80 and 180 MN/m 3 , respectively. A system of mutual coil support is being developed. Twisted coils in helical arrangement provide a reactor-sized HELIAC system. In order to reduce the magnetic ripple, a large number of 14 coils/FP in special arrangement is used

  19. NCSX Toroidal Field Coil Design

    International Nuclear Information System (INIS)

    Kalish M; Rushinski J; Myatt L; Brooks A; Dahlgren F; Chrzanowski J; Reiersen W; Freudenberg K.

    2005-01-01

    The National Compact Stellarator Experiment (NCSX) is an experimental device whose design and construction is underway at the Department of Energy's Princeton Plasma Physics Laboratory (PPPL). The primary coil systems for the NCSX device consist of the twisted plasma-shaping Modular Coils, the Poloidal Field Coils, and the Toroidal Field (TF) Coils. The TF Coils are D-shaped coils wound from hollow copper conductor, and vacuum impregnated with a glass-epoxy resin system. There are 18 identical, equally spaced TF coils providing 1/R field at the plasma. They operate within a cryostat, and are cooled by LN2, nominally, to 80K. Wedge shaped castings are assembled to the inboard face of these coils, so that inward radial loads are reacted via the nesting of each of the coils against their adjacent partners. This paper outlines the TF Coil design methodology, reviews the analysis results, and summarizes how the design and analysis support the design requirements

  20. Coil protection calculator for TFTR

    International Nuclear Information System (INIS)

    Marsala, R.J.; Woolley, R.D.

    1987-01-01

    A new coil protection calculator (CPC) is presented in this paper. It is now being developed for TFTR's magnetic field coils will replace the existing coil fault detector. The existing fault detector sacrifices TFTR operating capability for simplicity. The new CPC will permit operation up to the actual coil limits by accurately and continuously computing coil parameters in real-time. The improvement will allow TFTR to operate with higher plasma currents and will permit the optimization of pulse repetition rates

  1. Comparison of the association of sac growth and coil compaction with recurrence in coil embolized cerebral aneurysms.

    Directory of Open Access Journals (Sweden)

    Anna L Hoppe

    Full Text Available In recurrent cerebral aneurysms treated by coil embolization, coil compaction is regarded as the presumptive mechanism. We test the hypothesis that aneurysm growth is the primary recurrence mechanism. We also test the hypothesis that the coil mass will translate a measurable extent when recurrence occurs.An objective, quantitative image analysis protocol was developed to determine the volumes of aneurysms and coil masses during initial and follow-up visits from 3D rotational angiograms. The population consisted of 15 recurrence and 12 non-recurrence control aneurysms initially completely coiled at a single center. An investigator sensitivity study was performed to assess the objectivity of the methods. Paired Wilcoxon tests (p<0.05, one-tailed were performed to assess for aneurysm and coil growth. The translation of the coil mass center at follow-up was computed. A Mann Whitney U-Test (p<0.05, one-tailed was used to compare translation of coil mass centers between recurrence and control subjects.Image analysis protocol was found to be insensitive to the investigator. Aneurysm growth was evident in the recurrence cohort (p=0.003 but not the control (p=0.136. There was no evidence of coil compaction in either the recurrence or control cohorts (recurrence: p=0.339; control: p=0.429. The translation of the coil mass centers was found to be significantly larger in the recurrence cohort than the control cohort (p=0.047.Aneurysm sac growth, not coil compaction, was the primary mechanism of recurrence following successful coil embolization. The coil mass likely translates to a measurable extent when recurrence occurs and has the potential to serve as a non-angiographic recurrence marker.

  2. Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

    Science.gov (United States)

    Weinberger, Oliver; Winter, Lukas; Dieringer, Matthias A; Els, Antje; Oezerdem, Celal; Rieger, Jan; Kuehne, Andre; Cassara, Antonino M; Pfeiffer, Harald; Wetterling, Friedrich; Niendorf, Thoralf

    2016-01-01

    The purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation. Electromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each transmission regime flip angle distributions and blood-myocardium contrast are examined in a volunteer study of 12 subjects. The feasibility of the local transceiver RF coil array for cardiac chamber quantification at 3 Tesla is demonstrated. Our simulations and experiments demonstrate that cardiac MR at 3 Tesla using four-channel surface RF coil transmission is competitive versus current clinical CMR practice of large volume body RF coil transmission. The efficiency advantage of the 4TX/4RX setup facilitates shorter repetition times governed by local SAR limits versus body RF coil transmission at whole-body SAR limit. No statistically significant difference was found for cardiac chamber quantification derived with body RF coil versus four-channel surface RF coil transmission. Our simulation also show that the body RF coil exceeds local SAR limits by a factor of ~2 when driven at maximum applicable input power to reach the whole-body SAR limit. Pursuing local surface RF coil arrays for transmission in cardiac MR is a conceptually appealing alternative to body RF coil transmission, especially for patients with implants.

  3. Redesigning existing transcranial magnetic stimulation coils to reduce energy: application to low field magnetic stimulation

    Science.gov (United States)

    Wang, Boshuo; Shen, Michael R.; Deng, Zhi-De; Smith, J. Evan; Tharayil, Joseph J.; Gurrey, Clement J.; Gomez, Luis J.; Peterchev, Angel V.

    2018-06-01

    Objective. To present a systematic framework and exemplar for the development of a compact and energy-efficient coil that replicates the electric field (E-field) distribution induced by an existing transcranial magnetic stimulation coil. Approach. The E-field generated by a conventional low field magnetic stimulation (LFMS) coil was measured for a spherical head model and simulated in both spherical and realistic head models. Then, using a spherical head model and spatial harmonic decomposition, a spherical-shaped cap coil was synthesized such that its windings conformed to a spherical surface and replicated the E-field on the cortical surface while requiring less energy. A prototype coil was built and electrically characterized. The effect of constraining the windings to the upper half of the head was also explored via an alternative coil design. Main results. The LFMS E-field distribution resembled that of a large double-cone coil, with a peak field strength around 350 mV m‑1 in the cortex. The E-field distributions of the cap coil designs were validated against the original coil, with mean errors of 1%–3%. The cap coil required as little as 2% of the original coil energy and was significantly smaller in size. Significance. The redesigned LFMS coil is substantially smaller and more energy-efficient than the original, improving cost, power consumption, and portability. These improvements could facilitate deployment of LFMS in the clinic and potentially at home. This coil redesign approach can also be applied to other magnetic stimulation paradigms. Finally, the anatomically-accurate E-field simulation of LFMS can be used to interpret clinical LFMS data.

  4. Can radiological changes in lymph node volume during treatment predict success of radiation therapy in patients with locally advanced head and neck squamous cell carcinoma?

    International Nuclear Information System (INIS)

    Mishra, Sanju; Hammond, Alexander; Read, Nancy; Venkatesan, Varagur; Warner, Andrew; Winquist, Eric; Nichols, Anthony

    2013-01-01

    Assessment of nodal response after radiotherapy (RT) for head and neck squamous cell carcinoma is difficult, as both CT and positron emission tomography scanning have limited predictive value for residual disease. We sought to measure changes in nodal volume during RT to determine whether such changes are predictive of nodal disease control. Patients with locally advanced head and neck squamous cell carcinoma treated with 70Gy of radical RT (±chemotherapy or anti-epidermal growth factor receptor (EGFR) antibodies) were eligible. Baseline pre-RT scans and cone-beam CT scans done at the outset of treatment and at weeks 3, 5 and 7 (cone-beam CTs 1, 2, 3 and 4, respectively) were deformably coregistered, and 3D nodal volumes were measured. Thirty-eight eligible patients were identified. The main primary tumour site was oropharyngeal; most patients had stage IVa disease. Twenty-seven patients received concurrent platinum-based chemotherapy, 10 received only an EGFR inhibitor with RT and one received RT alone. Twelve patients had a failure in the neck. After week 1 of treatment, a 4% mean decrease in nodal volume was observed, increasing to 40% at week 7. Platinum-based chemotherapy achieved significantly greater decreases in nodal volume than EGFR inhibitors (44 vs. 25%; P=0.026). Advanced tumour stage predicted neck failure (P=0.002), but nodal volumes did not correlate with neck control. Changes in nodal volume are minimal initially during RT but accelerate during the latter weeks of therapy. This study suggests that chemotherapy achieves a greater decrease in nodal volume than EGFR inhibitors and that nodal changes do not predict disease control in the neck.

  5. The influence of quantitative tumor volume measurements on local control in advanced head and neck cancer using concomitant boost accelerated superfractionated irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Christopher R; Khandelwal, Shiv R; Schmidt-Ullrich, Rupert K; Ravalese, Joseph; Wazer, David E

    1995-06-15

    Purpose: Current methods to clinically define head and neck tumor bulk are qualitative and imprecise. Although the American Joint Committee on Cancer (AJCC) staging system is important for this purpose, limitations exist. This study will investigate the prognostic value of computed tomography (CT) derived tumor volume measurements in comparison to AJCC stage and other significant variables. Materials and Methods: Seventy-six patients with advanced head and neck squamous cell carcinoma were treated with concomitant boost accelerated superfractionated irradiation. Doses ranged from 68.4-73.8 Gy (median 70.2 Gy). Good quality pretherapy CT scans were available in 51 patients. Total tumor volume (TTV) estimates were derived from these scans using digital integration of primary tumor and metastatic lymphadenopathy. Actuarial and multivariate statistical techniques were applied to analyze local control. Results: Thirty-six-month local control was 63%. TTV ranged from 5-196 cm{sup 3} (median 35 cm{sup 3}) for all cases, 5-142 cm{sup 3} (median 17 cm{sup 3}) for those controlled, and 16-196 cm{sup 3} (median 47 cm{sup 3}) for local failures. There was a significant increase in failures above 35 cm{sup 3}. Univariate analysis found that TTV, T-stage, N-stage, and primary site were each significant prognostic variables. Local control for TTV {<=}35 cm{sup 3} was 92% at 36 months vs. 34% for TTV >35 cm{sup 3} (p = 0.0001). Multivariate analysis, however, found that TTV, primary site, and sex were important as independent variables; T and N stage were not independently significant unless TTV was removed from the model. Conclusions: This study demonstrates the prognostic significance of TTV in advanced carcinoma of the head and neck. This variable appears to be a more predictive than AJCC clinical stage. Quantitative tumor volume measurements may prove to be a useful parameter in future analyses of head and neck cancer.

  6. Superconducting coil protection

    International Nuclear Information System (INIS)

    Woods, E.L.

    1975-01-01

    The protection system is based on a two-phase construction program. Phase I is the development of a reliable hardwired relay control system with a digital loop utilizing firmware and a microprocessor controller. Phase II is an expansion of the digital loop to include many heretofore unmonitored coil variables. These new monitored variables will be utilized to establish early quench detection and to formulate confirmation techniques of the quench detection mechanism. Established quench detection methods are discussed and a new approach to quench detection is presented. The new circuit is insensitive to external pulsed magnetic fields and the associated induced voltages. Reliability aspects of the coil protection system are discussed with respect to shutdowns of superconducting coil systems. Redundance and digital system methods are presented as related topics

  7. The Impact of Positron Emission Tomography/Computed Tomography in Edge Delineation of Gross Tumor Volume for Head and Neck Cancers

    International Nuclear Information System (INIS)

    Ashamalla, Hani; Guirgius, Adel; Bieniek, Ewa; Rafla, Sameer; Evola, Alex; Goswami, Ganesh; Oldroyd, Randall; Mokhtar, Bahaa; Parikh, Kapila

    2007-01-01

    Purpose: To study anatomic biologic contouring (ABC), using a previously described distinct halo, to unify volume contouring methods in treatment planning for head and neck cancers. Methods and Materials: Twenty-five patients with head and neck cancer at various sites were planned for radiation therapy using positron emission tomography/computed tomography (PET/CT). The ABC halo was used in all PET/CT scans to contour the gross tumor volume (GTV) edge. The CT-based GTV (GTV-CT) and PET/CT-based GTV (GTV-ABC) were contoured by two independent radiation oncologists. Results: The ABC halo was observed in all patients studied. The halo had a standard unit value of 2.19 ± 0.28. The mean halo thickness was 2.02 ± 0.21 mm. Significant volume modification (≥25%) was seen in 17 of 25 patients (68%) after implementation of GTV-ABC. Concordance among observers was increased with the use of the halo as a guide for GTV determination: 6 patients (24%) had a ≤10% volume discrepancy with CT alone, compared with 22 (88%) with PET/CT (p 3 in CT-based planning to 7.2 cm 3 in PET/CT-based planning (p < 0.001). Conclusions: Using the 'anatomic biologic halo' to contour GTV in PET/CT improves consistency among observers. The distinctive appearance of the described halo and its presence in all of the studied tumors make it attractive for GTV contouring in head and neck tumors. Additional studies are needed to confirm the correlation of the halo with presence of malignant cells

  8. Impact of intra-arterial administration of boron compounds on dose-volume histograms in boron neutron capture therapy for recurrent head-and-neck tumors

    International Nuclear Information System (INIS)

    Suzuki, Minoru; Sakurai, Yoshinori; Nagata, Kenji; Kinashi, Yuko; Masunaga, Shinichiro; Ono, Koji; Maruhashi, Akira; Kato, Ituro; Fuwa, Nobukazu; Hiratsuka, Junichi; Imahori, Yoshio

    2006-01-01

    Purpose: To analyze the dose-volume histogram (DVH) of head-and-neck tumors treated with boron neutron capture therapy (BNCT) and to determine the advantage of the intra-arterial (IA) route over the intravenous (IV) route as a drug delivery system for BNCT. Methods and Materials: Fifteen BNCTs for 12 patients with recurrent head-and-neck tumors were included in the present study. Eight irradiations were done after IV administration of boronophenylalanine and seven after IA administration. The maximal, mean, and minimal doses given to the gross tumor volume were assessed using a BNCT planning system. Results: The results are reported as median values with the interquartile range. In the IA group, the maximal, mean, and minimal dose given to the gross tumor volume was 68.7 Gy-Eq (range, 38.8-79.9), 45.0 Gy-Eq (range, 25.1-51.0), and 13.8 Gy-Eq (range, 4.8-25.3), respectively. In the IV group, the maximal, mean, and minimal dose given to the gross tumor volume was 24.2 Gy-Eq (range, 21.5-29.9), 16.4 Gy-Eq (range, 14.5-20.2), and 7.8 Gy-Eq (range, 6.8-9.5), respectively. Within 1-3 months after BNCT, the responses were assessed. Of the 6 patients in the IV group, 2 had a partial response, 3 no change, and 1 had progressive disease. Of 4 patients in the IA group, 1 achieved a complete response and 3 a partial response. Conclusion: Intra-arterial administration of boronophenylalanine is a promising drug delivery system for head-and-neck BNCT

  9. Effects of Gradient Coil Noise and Gradient Coil Replacement on the Reproducibility of Resting State Networks.

    Science.gov (United States)

    Bagarinao, Epifanio; Tsuzuki, Erina; Yoshida, Yukina; Ozawa, Yohei; Kuzuya, Maki; Otani, Takashi; Koyama, Shuji; Isoda, Haruo; Watanabe, Hirohisa; Maesawa, Satoshi; Naganawa, Shinji; Sobue, Gen

    2018-01-01

    The stability of the MRI scanner throughout a given study is critical in minimizing hardware-induced variability in the acquired imaging data set. However, MRI scanners do malfunction at times, which could generate image artifacts and would require the replacement of a major component such as its gradient coil. In this article, we examined the effect of low intensity, randomly occurring hardware-related noise due to a faulty gradient coil on brain morphometric measures derived from T1-weighted images and resting state networks (RSNs) constructed from resting state functional MRI. We also introduced a method to detect and minimize the effect of the noise associated with a faulty gradient coil. Finally, we assessed the reproducibility of these morphometric measures and RSNs before and after gradient coil replacement. Our results showed that gradient coil noise, even at relatively low intensities, could introduce a large number of voxels exhibiting spurious significant connectivity changes in several RSNs. However, censoring the affected volumes during the analysis could minimize, if not completely eliminate, these spurious connectivity changes and could lead to reproducible RSNs even after gradient coil replacement.

  10. Selection and delineation of lymph node target volumes in head and neck conformal radiotherapy. proposal for standardizing terminology and procedure based on the surgical experience

    International Nuclear Information System (INIS)

    Gregoire, V.; Coche, E.; Cosnard, G.; Hamoir, M.; Reychler, H.

    2000-01-01

    The increasing use of 3D treatment planning in head and neck radiation oncology has created an urgent need for new guidelines for the selection and the delineation of the neck node areas to be included in the clinical target volume. Surgical literature has provided us with valuable information on the extent of pathological nodal involvement in the neck as a function of the primary tumor site. In addition, few clinical series have also reported information on radiological nodal involvement in those areas not commonly included in radical neck dissection. Taking all these data together, guidelines for the selection of the node levels to be irradiated for the major head and neck sites could be proposed. To fill the missing link between these Guidelines and the 3D treatment planning, recommendations for the delineation of these node levels (levels I-VI and retropharyngeal) on CT (or MRI) slices have been proposed using the guidelines outlined by the Committee for Head and Neck Surgery and Oncology of the American Academy for Otolarynology-Head and Neck Surgery. These guidelines were adapted to take into account specific radiological landmarks more easily identified on CT or MRI slices than in the operating field. (author)

  11. Nuclear magnetic resonance probe head design for precision strain control

    International Nuclear Information System (INIS)

    Kissikov, T.; Sarkar, R.; Bush, B. T.; Lawson, M.; Canfield, P. C.; Curro, N. J.

    2017-01-01

    Here, we present the design and construction of an NMR probe to investigate single crystals under strain at cryogenic temperatures. The probe head incorporates a piezoelectric-based apparatus from Razorbill Instruments that enables both compressive and tensile strain tuning up to strain values on the order of 0.3% with a precision of 0.001%. 75 As NMR in BaFe 2 As 2 reveals large changes to the electric field gradient and indicates that the strain is homogeneous to within 16% over the volume of the NMR coil.

  12. NET model coil test possibilities

    International Nuclear Information System (INIS)

    Erb, J.; Gruenhagen, A.; Herz, W.; Jentzsch, K.; Komarek, P.; Lotz, E.; Malang, S.; Maurer, W.; Noether, G.; Ulbricht, A.; Vogt, A.; Zahn, G.; Horvath, I.; Kwasnitza, K.; Marinucci, C.; Pasztor, G.; Sborchia, C.; Weymuth, P.; Peters, A.; Roeterdink, A.

    1987-11-01

    A single full size coil for NET/INTOR represents an investment of the order of 40 MUC (Million Unit Costs). Before such an amount of money or even more for the 16 TF coils is invested as much risks as possible must be eliminated by a comprehensive development programme. In the course of such a programme a coil technology verification test should finally prove the feasibility of NET/INTOR TF coils. This study report is almost exclusively dealing with such a verification test by model coil testing. These coils will be built out of two Nb 3 Sn-conductors based on two concepts already under development and investigation. Two possible coil arrangements are discussed: A cluster facility, where two model coils out of the two Nb 3 TF-conductors are used, and the already tested LCT-coils producing a background field. A solenoid arrangement, where in addition to the two TF model coils another model coil out of a PF-conductor for the central PF-coils of NET/INTOR is used instead of LCT background coils. Technical advantages and disadvantages are worked out in order to compare and judge both facilities. Costs estimates and the time schedules broaden the base for a decision about the realisation of such a facility. (orig.) [de

  13. Impact of magnetic field strength and receiver coil in ocular MRI: a phantom and patient study.

    Science.gov (United States)

    Erb-Eigner, K; Warmuth, C; Taupitz, M; Willerding, G; Bertelmann, E; Asbach, P

    2013-09-01

    Generally, high-resolution MRI of the eye is performed with small loop surface coils. The purpose of this phantom and patient study was to investigate the influence of magnetic field strength and receiver coils on image quality in ocular MRI. The eyeball and the complex geometry of the facial bone were simulated by a skull phantom with swine eyes. MR images were acquired with two small loop surface coils with diameters of 4 cm and 7 cm and with a multi-channel head coil at 1.5 and 3 Tesla, respectively. Furthermore, MRI of the eye was performed prospectively in 20 patients at 1.5 Tesla (7 cm loop surface coil) and 3 Tesla (head coil). These images were analysed qualitatively and quantitatively and statistical significance was tested using the Wilcoxon-signed-rank test (a p-value of less than 0.05 was considered to indicate statistical significance). The analysis of the phantom images yielded the highest mean signal-to-noise ratio (SNR) at 3 Tesla with the use of the 4 cm loop surface coil. In the phantom experiment as well as in the patient studies the SNR was higher at 1.5 Tesla by applying the 7 cm surface coil than at 3 Tesla by applying the head coil. Concerning the delineation of anatomic structures no statistically significant differences were found. Our results show that the influence of small loop surface coils on image quality (expressed in SNR) in ocular MRI is higher than the influence of the magnetic field strength. The similar visibility of detailed anatomy leads to the conclusion that the image quality of ocular MRI at 3 Tesla remains acceptable by applying the head coil as a receiver coil. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Trim coil power supplies

    International Nuclear Information System (INIS)

    Haisler, R.; Peeler, H.; Zajicek, W.

    1985-01-01

    The 18 trim coil power supplies have been constructed and are now in place in the K500 pit and pit mezzanine. Final wiring of the primary power and control power is proceeding along with installation of cooling water supplies. The supplies are expected to be ready for final testing into resistive loads at the beginning of June, 1985

  15. Asymptomatic Delayed Coil Migration from an Intracranial Aneurysm: A Case Report

    Directory of Open Access Journals (Sweden)

    Anirban Deep Banerjee

    2011-01-01

    Full Text Available Objective. To describe asymptomatic delayed migration of a coil loop in a patient following successful coil embolization of an anterior communicating artery saccular aneurysm. Methods. A 24-year-old man with a ruptured anterior communicating artery saccular aneurysm underwent coil embolization with one helical ultrasoft coil. Results. A followup CT scan head and a cerebral angiogram one month following the procedure revealed distal migration of an intra-aneurysmal coil loop into the left pericallosal artery. The patient, however, remained asymptomatic. Conclusion. Delayed migration of coil following embolization of an intracranial aneurysm is an extremely rare occurrence. An asymptomatic presentation, as in our patient, is even more unique. The stent-like configuration of the migrated spiral coil loop probably prevented complete occlusion of the blood vessel.

  16. The planning target volume margins detected by cone-beam CT in head and neck cancer patients treated by image-guided intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Liu Jun; Chen Hong; Zhang Guoqiao; Chen Fei; Zhang Li

    2011-01-01

    Objective: To determine the planning target volume margins of head and neck cancers treated by image guided radiotherapy (IGRT). Methods: 464 sets cone beam computed tomography (CBCT) images before setup correction and 126 sets CBCT images after correction were obtained from 51 head and neck cancer patients treated by IGRT in our department. The systematic and random errors were evaluated by either online or offline correction through registering the CBCT images to the planning CT. The data was divided into 3 groups according to the online correction times. Results: The isocenter shift were 0.37 mm ± 2.37 mm, -0.43 mm ± 2.30 mm and 0.47 mm ± 2.65 mm in right-left (RL), anterior-posterior (AP) and superior-inferior (SI) directions respectively before correction, and it reduced to 0.08 mm ± 0.68 mm, -0.03 mm ± 0.74 mm and 0.03 mm ± 0.80 mm when evaluated by 126 sets corrected CBCT images. The planning target volume (PTV) margin from clinical target volume (CTV) before correction were: 6.41 mm, 6.15 mm and 7.10 mm based on two parameter model, and it reduced to 1.78 mm, 1.80 mm and 1.97 mm after correction. The PTV margins were 3.8 mm, 3.8 mm, 4.0 mm; 4.0 mm, 4.0 mm, 5.0 mm and 5.4 mm, 5.2 mm, 6.1 mm in RL, AP and SI respectively when online-correction times were more than 15 times, 11-15 times, 5-10 times. Conclusions: CBCT-based on online correction reduce the PTV margin for head and neck cancers treated by IGRT and ensure more precise dose delivery and less normal tissue complications. (authors)

  17. Changes in lateral dimensions of irradiated volume and their impact on the accuracy of dose delivery during radiotherapy for head and neck cancer

    International Nuclear Information System (INIS)

    Senkus-Konefka, Elzbieta; Naczk, Edmund; Borowska, Ilona; Badzio, Andrzej; Jassem, Jacek

    2006-01-01

    Background and purpose: To assess changes in lateral dimensions of irradiated volume during head and neck cancer radiotherapy and to determine their impact on the accuracy of dose delivery. Patients and methods: Lateral dimensions of irradiated volumes were measured in five predefined points prior to treatment and then bi-weekly. For each measurement, midline dose was calculated and verified using in vivo dosimetry. Early radiation reactions, patient weight changes and the need to modify radiotherapy accessories were also recorded. The study included 33 head and neck cancer patients irradiated using parallel opposed megavoltage fields. Results: Body mass changes during radiotherapy ranged from -18 to +4 kg (median -5). Lateral dimension changes >5 mm (range -37 to +16) occurred in 32 patients (97%). For axis measurements, the degree of lateral dimension changes were correlated with treatment field size (P=0.022) and degree of mucositis (P=0.017). Axis doses calculated for changed dimensions varied from those prescribed by -2.5 to +6% (median +2%). Differences larger than 5% were present in 4.8% of calculations. In 17 patients (52%), radiotherapy accessories had to be modified during treatment. The need to modify radiotherapy accessories correlated with larger treatment portals (P=0.004), more weight loss during treatment (P=0.01) and higher initial N stage (P=0.04). Conclusions: Changes of irradiated volume lateral dimensions during head and neck cancer radiotherapy may lead to considerable dose delivery inaccuracies. Watchful monitoring, corrections to calculated dose when changes observed are significant and radiotherapy accessories modification during the course of treatment are strongly recommended

  18. Surface and volume three-dimensional displays of Tc-99m HMPAO brain SPECT images in stroke patients with three-head gamma camera

    International Nuclear Information System (INIS)

    Shih, W.J.; Slevin, J.T.; Schleenbaker, R.E.; Mills, B.J.; Magoun, S.L.; Ryo, U.Y.

    1991-01-01

    This paper evaluates volume and surface 3D displays in Tc-99m HMPAO brain SPECT imaging in stroke patients. Using a triple-head gamma camera interfaced with a 64-bit supercomputer, 20 patients with stroke were studied. Each patient was imaged 30-60 minutes after an intravenous injection of 20 mCi of Tc-99m HMPAO. SPECT images as well as planar images were routinely obtained; volume and surface 3D display then proceeded, with the process requiring 5-10 minutes. Volume and surface 3D displays show the brain from all angles; thus the location and extension of lesion(s) in the brain are much easier to appreciate. While a cerebral lesion(s) was more clearly delineated by surface 3D imaging, crossed cerebellar diaschisis in seven patients was clearly exhibited with volume 3D but not with surface 3D imaging. Volume and surface 3D displays enhance continuity of structures and understanding of spatial relationships

  19. Quantitative dose-volume response analysis of changes in parotid gland function after radiotherapy in the head-and-neck region

    International Nuclear Information System (INIS)

    Roesink, Judith M.; Moerland, Marinus A.; Battermann, Jan J.; Hordijk, Gerrit Jan; Terhaard, Chris H.J.

    2001-01-01

    Purpose: To study the radiation tolerance of the parotid glands as a function of dose and volume irradiated. Methods and Materials: One hundred eight patients treated with primary or postoperative radiotherapy for various malignancies in the head-and-neck region were prospectively evaluated. Stimulated parotid flow rate was measured before radiotherapy and 6 weeks, 6 months, and 1 year after radiotherapy. Parotid gland dose-volume histograms were derived from CT-based treatment planning. The normal tissue complication probability model proposed by Lyman was fit to the data. A complication was defined as stimulated parotid flow rate 50 (the dose to the whole organ leading to a complication probability of 50%) was found to be 31, 35, and 39 Gy at 6 weeks, 6 months, and 1 year postradiotherapy, respectively. The volume dependency parameter n was around 1, which means that the mean parotid dose correlates best with the observed complications. There was no steep dose-response curve (m=0.45 at 1 year postradiotherapy). Conclusions: This study on dose/volume/parotid gland function relationships revealed a linear correlation between postradiotherapy flow ratio and parotid gland dose and a strong volume dependency. No threshold dose was found. Recovery of parotid gland function was shown at 6 months and 1 year after radiotherapy. In radiation planning, attempts should be made to achieve a mean parotid gland dose at least below 39 Gy (leading to a complication probability of 50%)

  20. Sensitivity of an eight-element phased array coil in 3 Tesla MR imaging: a basic analysis.

    Science.gov (United States)

    Hiratsuka, Yoshiyasu; Miki, Hitoshi; Kikuchi, Keiichi; Kiriyama, Ikuko; Mochizuki, Teruhito; Takahashi, Shizue; Sadamoto, Kazuhiko

    2007-01-01

    To evaluate the performance advantages of an 8-element phased array head coil (8 ch coil) over a conventional quadrature-type birdcage head coil (QD coil) with regard to the signal-to-noise ratio (SNR) and image uniformity in 3 Tesla magnetic resonance (MR) imaging. We scanned a phantom filled with silicon oil using an 8 ch coil and a QD coil in a 3T MR imaging system and compared the SNR and image uniformity obtained from T(1)-weighted spin echo (SE) images and T(2)-weighted fast SE images between the 2 coils. We also visually evaluated images from 4 healthy volunteers. The SNR with the 8 ch coil was approximately twice that with the QD coil in the region of interest (ROI), which was set as 75% of the area in the center of the phantom images. With regard to the spatial variation of sensitivity, the SNR with the 8 ch coil was lower at the center of the images than at the periphery, whereas the SNR with the QD coil exhibited an inverse pattern. At the center of the images with the 8 ch coil, the SNR was somewhat lower, and that distribution was relatively flat compared to that in the periphery. Image uniformity varied less with the 8 ch coil than with the QD coil on both imaging sequences. The 8 ch phased array coil was useful for obtaining high quality 3T images because of its higher SNR and improved image uniformity than those obtained with conventional quadrature-type birdcage head coil.

  1. Eccentric Coil Test Facility (ECTF)

    International Nuclear Information System (INIS)

    Burn, P.B.; Walstrom, P.L.; Anderson, W.C.; Marguerat, E.F.

    1975-01-01

    The conceptual design of a facility for testing superconducting coils under some conditions peculiar to tokamak systems is given. A primary element of the proposed facility is a large 25 MJ background solenoid. Discussions of the mechanical structure, the stress distribution and the thermal stability for this coil are included. The systems for controlling the facility and diagnosing test coil behavior are also described

  2. Modular coils: a promising toroidal-reactor-coil system

    International Nuclear Information System (INIS)

    Chu, T.K.; Furth, H.P.; Johnson, J.L.; Ludescher, C.; Weimer, K.E.

    1981-04-01

    The concept of modular coils originated from a need to find reactor-relevant stellarator windings, but its usefulness can be extended to provide an externally applied, additional rotational transform in tokamaks. Considerations of (1) basic principles of modular coils, (2) types of coils, (3) types of configurations (general, helically symmetric, helically asymmetric, with magnetic well, with magnetic hill), (4) types of rotational transform profile, and (5) structure and origin of ripples are given. These results show that modular coils can offer a wide range of vacuum magnetic field configurations, some of which cannot be obtained with the classical stellarator or torsatron coil configuration

  3. Coil Tolerance Impact on Plasma Surface Quality for NCSX

    International Nuclear Information System (INIS)

    Brooks, Art; Reiersen, Wayne

    2003-01-01

    The successful operation of the National Compact Stellarator Experiment (NCSX) machine will require producing plasma configurations with good flux surfaces, with a minimum volume of the plasma lost to magnetic islands or stochastic regions. The project goal is to achieve good flux surfaces over 90% of the plasma volume. NCSX is a three period device designed to be operated with iota ranging from ∼0.4 on axis to ∼0.7 at the edge. The field errors of most concern are those that are resonant with 3/5 and 3/6 modes (for symmetry preserving field errors) and the 1/2 and 2/3 modes (for symmetry breaking field errors). In addition to losses inherent in the physics configuration itself, there will be losses from field errors arising from coil construction and assembly errors. Some of these losses can be recovered through the use of trim coils or correction coils. The impact of coil tolerances on plasma surface quality is evaluated herein for the NCSX design. The methods used in this evaluation are discussed. The ability of the NCSX trim coils to correct for field errors is also examined. The results are used to set coils tolerances for the various coil systems

  4. The impact of preload reduction with head-up tilt testing on longitudinal and transverse left ventricular mechanics: a study utilizing deformation volume analysis.

    Science.gov (United States)

    Schneider, Caroline; Forsythe, Lynsey; Somauroo, John; George, Keith; Oxborough, David

    2018-03-01

    Left ventricular (LV) function is dependent on load, intrinsic contractility and relaxation with a variable impact on specific mechanics. Strain (ε) imaging allows the assessment of cardiac function; however, the direct relationship between volume and strain is currently unknown. The aim of this study was to establish the impact of preload reduction through head-up tilt (HUT) testing on simultaneous left ventricular (LV) longitudinal and transverse function and their respective contribution to volume change. A focused transthoracic echocardiogram was performed on 10 healthy male participants (23 ± 3 years) in the supine position and following 1 min and 5 min of HUT testing. Raw temporal longitudinal ε (Ls) and transverse ε (Ts) values were exported and divided into 5% increments across the cardiac cycle and corresponding LV volumes were traced at each 5% increment. This provided simultaneous LV longitudinal and transverse ε and volume loops (deformation volume analysis - DVA). There was a leftward shift of the ε-volume loop from supine to 1 min and 5 min of HUT ( P  transverse thickening from supine to 1 min, which was further augmented at 5 min ( P  = 0.018). Preload reduction occurs within 1 min of HUT but does not further reduce at 5 min. This decline is associated with a decrease in longitudinal ε and concomitant increase in transverse ε. Consequently, augmented transverse relaxation appears to be an important factor in the maintenance of LV filling in the setting of reduced preload. DVA provides information on the relative contribution of mechanics to a change in LV volume and may have a role in the assessment of clinical populations. © 2018 The authors.

  5. Numerical characterization of a flexible circular coil for magnetic resonance imaging

    Science.gov (United States)

    Bautista, T.; Hernandez, R.; Solis-Najera, S. E.; Rodriguez, A. O.

    2012-10-01

    Numerical simulations of the magnetic field generated by a flexible surface coil were conducted to study its behavior for applications of animal models at 7 Tesla. This coil design is able to fully cover a volume of interest. The Finite Difference Method in Time Domain (FDTD) was used because of its ability to accurately model complex problems in electromagnetism. This particular coil design is best suited for regions of interests with a spherical shape, since B1 uniformity is not significantly attenuated as in the case of a circular-loop coil. It still remains to investigate the feasibility to actually construct a coil prototype.

  6. Target volume delineation for head and neck cancer intensity-modulated radiotherapy; Delineation des volumes cibles des cancers des voies aerodigestives superieures en radiotherapie conformationnelle avec modulation d'intensite

    Energy Technology Data Exchange (ETDEWEB)

    Lapeyre, M.; Toledano, I.; Bourry, N. [Departement de radiotherapie, centre Jean-Perrin, 58, rue Montalembert, BP 5026, 63011 Clermont-Ferrand cedex 1 (France); Bailly, C. [Unite de radiodiagnostic, centre Jean-Perrin, 58, rue Montalembert, BP 5026, 63011 Clermont-Ferrand cedex 1 (France); Cachin, F. [Unite de medecine nucleaire, centre Jean-Perrin, 58, rue Montalembert, BP 5026, 63011 Clermont-Ferrand cedex 1 (France)

    2011-10-15

    This article describes the determination and the delineation of the target volumes for head-and-neck cancers treated with intensity-modulated radiotherapy (IMRT). The delineation of the clinical target volumes (CTV) on the computerized tomography scanner (CT scan) requires a rigorous methodology due to the complexity of head-and-neck anatomy. The clinical examination with a sketch of pretreatment tumour extension, the surgical and pathological reports and the adequate images (CT scan, magnetic resonance imaging and fluorodeoxyglucose positron emission tomography) are necessary for the delineation. The target volumes depend on the overall strategy: sequential IMRT or simultaneous integrated boost-IMRT (SIB-IMRT). The concept of selectivity of the potential subclinical disease near the primary tumor and the selection of neck nodal targets are described according to the recommendations and the literature. The planing target volume (PTV), mainly reflecting setup errors (random and systematic), results from a uniform 4-5 mm expansion around the CTV. We propose the successive delineation of: (1) the gross volume tumour (GTV); (2) the 'high risk' CTV1 around the GTV or including the postoperative tumour bed in case of positive margins or nodal extra-capsular spread (65-70 Gy in 30-35 fractions); (3) the CTV2 'intermediate risk' around the CTV1 for SIB-IMRT (59-63 Gy in 30-35 fractions); (4) the 'low-risk' CTV3 (54-56 Gy in 30-35 fractions); (5) the PTVs. (authors)

  7. Dose–Volume Modeling of Brachial Plexus-Associated Neuropathy After Radiation Therapy for Head-and-Neck Cancer: Findings From a Prospective Screening Protocol

    International Nuclear Information System (INIS)

    Chen, Allen M.; Wang, Pin-Chieh; Daly, Megan E.; Cui, Jing; Hall, William H.; Vijayakumar, Srinivasan; Phillips, Theodore L.; Farwell, D. Gregory; Purdy, James A.

    2014-01-01

    Purpose: Data from a prospective screening protocol administered for patients previously irradiated for head-and-neck cancer was analyzed to identify dosimetric predictors of brachial plexus-associated neuropathy. Methods and Materials: Three hundred fifty-two patients who had previously completed radiation therapy for squamous cell carcinoma of the head and neck were prospectively screened from August 2007 to April 2013 using a standardized self-administered instrument for symptoms of neuropathy thought to be related to brachial plexus injury. All patients were disease-free at the time of screening. The median time from radiation therapy was 40 months (range, 6-111 months). A total of 177 patients (50%) underwent neck dissection. Two hundred twenty-one patients (63%) received concurrent chemotherapy. Results: Fifty-one patients (14%) reported brachial plexus-related neuropathic symptoms with the most common being ipsilateral pain (50%), numbness/tingling (40%), and motor weakness and/or muscle atrophy (25%). The 3- and 5-year estimates of freedom from brachial plexus-associated neuropathy were 86% and 81%, respectively. Clinical/pathological N3 disease (P<.001) and maximum radiation dose to the ipsilateral brachial plexus (P=.01) were significantly associated with neuropathic symptoms. Cox regression analysis revealed significant dose–volume effects for brachial plexus-associated neuropathy. The volume of the ipsilateral brachial plexus receiving >70 Gy (V70) predicted for symptoms, with the incidence increasing with V70 >10% (P<.001). A correlation was also observed for the volume receiving >74 Gy (V74) among patients treated without neck dissection, with a cutoff of 4% predictive of symptoms (P=.038). Conclusions: Dose–volume guidelines were developed for radiation planning that may limit brachial plexus-related neuropathies

  8. Dose–Volume Modeling of Brachial Plexus-Associated Neuropathy After Radiation Therapy for Head-and-Neck Cancer: Findings From a Prospective Screening Protocol

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Allen M., E-mail: amchen@mednet.ucla.edu [Department of Radiation Oncology, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California (United States); Wang, Pin-Chieh [Department of Radiation Oncology, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California (United States); Daly, Megan E.; Cui, Jing; Hall, William H. [Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California (United States); Vijayakumar, Srinivasan [Department of Radiation Oncology, University of Mississippi School of Medicine, Jackson, Mississippi (United States); Phillips, Theodore L. [Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California (United States); Farwell, D. Gregory [Department of Otolaryngology–Head and Neck Surgery, University of California, Davis, Comprehensive Cancer Center, Sacramento, California (United States); Purdy, James A. [Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California (United States)

    2014-03-15

    Purpose: Data from a prospective screening protocol administered for patients previously irradiated for head-and-neck cancer was analyzed to identify dosimetric predictors of brachial plexus-associated neuropathy. Methods and Materials: Three hundred fifty-two patients who had previously completed radiation therapy for squamous cell carcinoma of the head and neck were prospectively screened from August 2007 to April 2013 using a standardized self-administered instrument for symptoms of neuropathy thought to be related to brachial plexus injury. All patients were disease-free at the time of screening. The median time from radiation therapy was 40 months (range, 6-111 months). A total of 177 patients (50%) underwent neck dissection. Two hundred twenty-one patients (63%) received concurrent chemotherapy. Results: Fifty-one patients (14%) reported brachial plexus-related neuropathic symptoms with the most common being ipsilateral pain (50%), numbness/tingling (40%), and motor weakness and/or muscle atrophy (25%). The 3- and 5-year estimates of freedom from brachial plexus-associated neuropathy were 86% and 81%, respectively. Clinical/pathological N3 disease (P<.001) and maximum radiation dose to the ipsilateral brachial plexus (P=.01) were significantly associated with neuropathic symptoms. Cox regression analysis revealed significant dose–volume effects for brachial plexus-associated neuropathy. The volume of the ipsilateral brachial plexus receiving >70 Gy (V70) predicted for symptoms, with the incidence increasing with V70 >10% (P<.001). A correlation was also observed for the volume receiving >74 Gy (V74) among patients treated without neck dissection, with a cutoff of 4% predictive of symptoms (P=.038). Conclusions: Dose–volume guidelines were developed for radiation planning that may limit brachial plexus-related neuropathies.

  9. Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

    OpenAIRE

    Weinberger, Oliver; Winter, Lukas; Dieringer, Matthias A.; Els, Antje; Oezerdem, Celal; Rieger, Jan; Kuehne, Andre; Cassara, Antonino M.; Pfeiffer, Harald; Wetterling, Friedrich; Niendorf, Thoralf

    2016-01-01

    INTRODUCTION: The purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation. METHODS: Electromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each...

  10. Supporting device for Toroidal coils

    International Nuclear Information System (INIS)

    Araki, Takao.

    1985-01-01

    Purpose: To reduce the response of a toroidal coil supporting device upon earthquakes and improve the earthquake proofness in a tokamak type thermonuclear device. Constitution: Structural materials having large longitudinal modulus and enduring great stresses, for example, stainless steels are used as the toroidal coil supporting legs and heat insulating structural materials are embedded in a nuclear reactor base mats below the supporting legs. Furthermore, heat insulating concretes are spiked around the heat insulating structural materials to prevent the intrusion of heat to the toroidal coils. The toroidal coils are kept at cryogenic state and superconductive state for the conductors. In this way, the period of proper vibrations of the toroidal coils and the toroidal coil supporting structures can be shortened thereby decreasing the seismic response. Furthermore, since the strength of the supporting legs is increased, the earthquake proofness of the coils can be improved. (Kamimura, M.)

  11. The significant impact of framing coils on long-term outcomes in endovascular coiling for intracranial aneurysms: how to select an appropriate framing coil.

    Science.gov (United States)

    Ishida, Wataru; Sato, Masayuki; Amano, Tatsuo; Matsumaru, Yuji

    2016-09-01

    OBJECTIVE The importance of a framing coil (FC)-the first coil inserted into an aneurysm during endovascular coiling, also called a lead coil or a first coil-is recognized, but its impact on long-term outcomes, including recanalization and retreatment, is not well established. The purposes of this study were to test the hypothesis that the FC is a significant factor for aneurysmal recurrence and to provide some insights on appropriate FC selection. METHODS The authors retrospectively reviewed endovascular coiling for 280 unruptured intracranial aneurysms and gathered data on age, sex, aneurysm location, aneurysm morphology, maximal size, neck width, adjunctive techniques, recanalization, retreatment, follow-up periods, total volume packing density (VPD), volume packing density of the FC, and framing coil percentage (FCP; the percentage of FC volume in total coil volume) to clarify the associated factors for aneurysmal recurrence. RESULTS Of 236 aneurysms included in this study, 33 (14.0%) had recanalization, and 18 (7.6%) needed retreatment during a mean follow-up period of 37.7 ± 16.1 months. In multivariate analysis, aneurysm size (odds ratio [OR] = 1.29, p < 0.001), FCP < 32% (OR 3.54, p = 0.009), and VPD < 25% (OR 2.96, p = 0.015) were significantly associated with recanalization, while aneurysm size (OR 1.25, p < 0.001) and FCP < 32% (OR 6.91, p = 0.017) were significant predictors of retreatment. VPD as a continuous value or VPD with any cutoff value could not predict retreatment with statistical significance in multivariate analysis. CONCLUSIONS FCP, which is equal to the FC volume as a percentage of the total coil volume and is unaffected by the morphology of the aneurysm or the measurement error in aneurysm length, width, or height, is a novel predictor of recanalization and retreatment and is more significantly predictive of retreatment than VPD. To select FCs large enough to meet the condition of FCP ≥ 32% is a potential relevant factor for better

  12. A highly detailed FEM volume conductor model based on the ICBM152 average head template for EEG source imaging and TCS targeting.

    Science.gov (United States)

    Haufe, Stefan; Huang, Yu; Parra, Lucas C

    2015-08-01

    In electroencephalographic (EEG) source imaging as well as in transcranial current stimulation (TCS), it is common to model the head using either three-shell boundary element (BEM) or more accurate finite element (FEM) volume conductor models. Since building FEMs is computationally demanding and labor intensive, they are often extensively reused as templates even for subjects with mismatching anatomies. BEMs can in principle be used to efficiently build individual volume conductor models; however, the limiting factor for such individualization are the high acquisition costs of structural magnetic resonance images. Here, we build a highly detailed (0.5mm(3) resolution, 6 tissue type segmentation, 231 electrodes) FEM based on the ICBM152 template, a nonlinear average of 152 adult human heads, which we call ICBM-NY. We show that, through more realistic electrical modeling, our model is similarly accurate as individual BEMs. Moreover, through using an unbiased population average, our model is also more accurate than FEMs built from mismatching individual anatomies. Our model is made available in Matlab format.

  13. Toxicological effects of prolonged and intense use of mosquito coil emission in rats and its implications on malaria control

    Directory of Open Access Journals (Sweden)

    Emmanuel Taiwo Idowu

    2013-09-01

    Full Text Available Efectos toxicológicos del uso prolongado e intenso de emisiones de espirales contra mosquitos en ratas y sus implicaciones sobre el control de la malaria. Mosquito coil is a vector control option used to prevent malaria in low income counties, while some studies have addressed this issue, additional reseach is required to increase knowledge on the adverse health effects caused by the prolonged use of coils. In this study we investigated the toxicological effects of fumes from two locally manufactured mosquito coil insecticides (with pyrethroids: transfluthrin and d-allethrin as active ingredients on male albino rats. For this, we recorded the haematological and biochemical indices, and made histopathology and mutagenicity evaluations in rats exposed to mosquito fumes during 2, 4, 8, 12 and 16 week periods. Haematological determination was performed using automated hematology analyzer to determine White Blood Cell (WBC, Packed Cell Volume (PCV, Red Blood Cell (RBC and Platelet (PLT counts, while biochemical evaluations were determined using available commercial kits. Gross histopathological changes were studied for the kidney, liver and lungs in sacrificed rats. The rat sperm head abnormalities assessment was used to evaluate mutagenicity. Mosquito coil fumes produced significant increase (P0.05. Mutagenicity assessment revealed sperm abnormality was statistically significant (P<0.05 compared with the control at 8, 12 and 16 weeks post exposure to transfluthrin. Histological studies revealed severe lung damage evidenced by interstitial accumulations, pulmonary oedema and emphysema in exposed rats. Intracellular accumulations and severe sinusoidal congestion of liver cells were observed from 12 weeks exposure, indicating liver damage. Our studies indicate that mosquito coil fumes do initiate gradual damage to the host. These pathological effects must be taken into consideration by the malaria control program, particularly when regulating their

  14. The potential advantages of (18)FDG PET/CT-based target volume delineation in radiotherapy planning of head and neck cancer.

    Science.gov (United States)

    Moule, Russell N; Kayani, Irfan; Moinuddin, Syed A; Meer, Khalda; Lemon, Catherine; Goodchild, Kathleen; Saunders, Michele I

    2010-11-01

    This study investigated two fixed threshold methods to delineate the target volume using (18)FDG PET/CT before and during a course of radical radiotherapy in locally advanced squamous cell carcinoma of the head and neck. Patients were enrolled into the study between March 2006 and May 2008. (18)FDG PET/CT scans were carried out 72h prior to the start of radiotherapy and then at 10, 44 and 66Gy. Functional volumes were delineated according to the SUV Cut Off (SUVCO) (2.5, 3.0, 3.5, and 4.0bwg/ml) and percentage of the SUVmax (30%, 35%, 40%, 45%, and 50%) thresholds. The background (18)FDG uptake and the SUVmax within the volumes were also assessed. Primary and lymph node volumes for the eight patients significantly reduced with each increase in the delineation threshold (for example 2.5-3.0bwg/ml SUVCO) compared to the baseline threshold at each imaging point. There was a significant reduction in the volume (p⩽0.0001-0.01) after 36Gy compared to the 0Gy by the SUVCO method. There was a negative correlation between the SUVmax within the primary and lymph node volumes and delivered radiation dose (p⩽0.0001-0.011) but no difference in the SUV within the background reference region. The volumes delineated by the PTSUVmax method increased with the increase in the delivered radiation dose after 36Gy because the SUVmax within the region of interest used to define the edge of the volume was equal or less than the background (18)FDG uptake and the software was unable to effectively differentiate between tumour and background uptake. The changes in the target volumes delineated by the SUVCO method were less susceptible to background (18)FDG uptake compared to those delineated by the PTSUVmax and may be more helpful in radiotherapy planning. The best method and threshold have still to be determined within institutions, both nationally and internationally. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  15. Study on the optimum design of a high temperature superconducting coil

    International Nuclear Information System (INIS)

    Ishiguri, Shinichi; Yamaguchi, Mitsugi; Fukui, Satoshi; Ogawa, Jun; Sato, Takao

    2005-01-01

    It is in particular of importance for HTS coils to secure a larger central magnetic field, a large stored energy, etc. with shorter length of HTS tapes. The critical current of an HTS tape depends on both the flux density and the flux angle with respect to tapes. In view of this, the performance improvement of HTS coils is taken into account with an analytical model. As a coil shape, the minimum volume coil derived from the Fabry Factor constant curve is taken up, which is often employed at low temperature coils. The electric field distribution within a coil cross-section is calculated to examine effects on a current carrying capability. It is clear that high electric field portions appear at the coil edge region due primarily to inclined magnetic fluxes against HTS tapes. Considering this, a grade winding method of a coil is proposed, where the winding density of conductors is reduced at coil edge portions. With this coil winding structure, the critical current of an HTS coil is improved since the magnetic field is reduced at edge portions. The stored energy per HTS tape length and the central magnetic field of the coil can be remarkably increased by this kind of grade winding method

  16. Compressing DNA sequence databases with coil

    Directory of Open Access Journals (Sweden)

    Hendy Michael D

    2008-05-01

    Full Text Available Abstract Background Publicly available DNA sequence databases such as GenBank are large, and are growing at an exponential rate. The sheer volume of data being dealt with presents serious storage and data communications problems. Currently, sequence data is usually kept in large "flat files," which are then compressed using standard Lempel-Ziv (gzip compression – an approach which rarely achieves good compression ratios. While much research has been done on compressing individual DNA sequences, surprisingly little has focused on the compression of entire databases of such sequences. In this study we introduce the sequence database compression software coil. Results We have designed and implemented a portable software package, coil, for compressing and decompressing DNA sequence databases based on the idea of edit-tree coding. coil is geared towards achieving high compression ratios at the expense of execution time and memory usage during compression – the compression time represents a "one-off investment" whose cost is quickly amortised if the resulting compressed file is transmitted many times. Decompression requires little memory and is extremely fast. We demonstrate a 5% improvement in compression ratio over state-of-the-art general-purpose compression tools for a large GenBank database file containing Expressed Sequence Tag (EST data. Finally, coil can efficiently encode incremental additions to a sequence database. Conclusion coil presents a compelling alternative to conventional compression of flat files for the storage and distribution of DNA sequence databases having a narrow distribution of sequence lengths, such as EST data. Increasing compression levels for databases having a wide distribution of sequence lengths is a direction for future work.

  17. Trends in tungsten coil atomic spectrometry

    Science.gov (United States)

    Donati, George L.

    Renewed interest in electrothermal atomic spectrometric methods based on tungsten coil atomizers is a consequence of a world wide increasing demand for fast, inexpensive, sensitive, and portable analytical methods for trace analysis. In this work, tungsten coil atomic absorption spectrometry (WCAAS) and tungsten coil atomic emission spectrometry (WCAES) are used to determine several different metals and even a non-metal at low levels in different samples. Improvements in instrumentation and new strategies to reduce matrix effects and background signals are presented. Investigation of the main factors affecting both WCAAS and WCAES analytical signals points to the importance of a reducing, high temperature gas phase in the processes leading to atomic cloud generation. Some more refractory elements such as V and Ti were determined for the first time by double tungsten coil atomic emission spectrometry (DWCAES). The higher temperatures provided by two atomizers in DWCAES also allowed the detection of Ag, Cu and Sn emission signals for the first time. Simultaneous determination of several elements by WCAES in relatively complex sample matrices was possible after a simple acid extraction. The results show the potential of this method as an alternative to more traditional, expensive methods for fast, more effective analyses and applications in the field. The development of a new metallic atomization cell is also presented. Lower limits of detection in both WCAAS and WCAES determinations were obtained due to factors such as better control of background signal, smaller, more isothermal system, with atomic cloud concentration at the optical path for a longer period of time. Tungsten coil-based methods are especially well suited to applications requiring low sample volume, low cost, sensitivity and portability. Both WCAAS and WCAES have great commercial potential in fields as diverse as archeology and industrial quality control. They are simple, inexpensive, effective

  18. Dental MRI using a dedicated RF-coil at 3 Tesla.

    Science.gov (United States)

    Prager, Marcel; Heiland, Sabine; Gareis, Daniel; Hilgenfeld, Tim; Bendszus, Martin; Gaudino, Chiara

    2015-12-01

    To assess the benefit of a dedicated surface coil to visualize dental structures in comparison to standard head/neck coil. Measurements were performed using the standard head/neck coil and a dedicated array coil for dental MRI at 3 T. As MRI methods, we used a T1-weighted spin-echo sequence with and without spectral fat saturation, a T2-weighted turbo-spin-echo sequence and a 3-dimensional T2-weighted SPACE sequence. Measurements were performed in a phantom to examine sensitivity profiles. Then the signal gain in dental structures was examined in volunteers and in a patient. As expected for a surface coil, the signal gain of the dental coil was highest at the surface of the phantom and decreased with increasing distance to the coil; it was >120% even at a depth of 30 mm, measured from the centre of the coil. The signal gain within the pulp of the volunteers ranged between 236 and 413%. The dedicated array coil offers a significantly higher signal within the region of interest for dental MR imaging thus allowing for better depiction of pathologies within the periodontium and for delineation and tracking of the branches of the maxillary and mandibular nerves. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  19. Tumor Volume and Metabolism of Prostate Cancer Determined by Proton Magnetic Resonance Spectroscopic Imaging at 3T Without Endorectal Coil Reveal Potential Clinical Implications in the Context of Radiation Oncology

    International Nuclear Information System (INIS)

    Crehange, Gilles; Parfait, Sebastien; Liegard, Melanie; Maingon, Philippe; Ben Salem, Douraied; Cochet, Alexandre; Funes de la Vega, Mathilde; Cormier, Luc; Bonnetain, Franck; Mirjolet, Celine; Brunotte, Francois; Walker, Paul M.

    2011-01-01

    Purpose: To determine whether a relationship exists between the tumor volume (TV) or relative choline content determined using magnetic resonance spectroscopy imaging (MRSI) at 3T and the clinical prognostic parameters for patients with localized prostate cancer (PCa). Methods and Materials: A total of 72 men (mean age, 67.8 ± 6.2 years) were stratified as having low-risk (n = 26), intermediate-risk (n = 24), or high-risk (n = 22) PCa. MRSI was performed at 3T using a phased-array coil. Spectra are expressed as the total choline/citrate, total choline plus creatine/citrate, and total choline plus polyamines plus creatine/citrate ratios. The mean ratio of the most pathologic voxels and the MRSI-based TV were also determined. Results: The mean values of the total choline/citrate, total choline plus creatine/citrate, and total choline plus polyamine plus creatine/citrate ratios were greater for Stage T2b or greater tumors vs. Stage T2a or less tumors: 7.53 ± 13.60 vs. 2.31 ± 5.65 (p = .018), 8.98 ± 14.58 vs. 2.56 ± 5.70 (p = .016), and 10.32 ± 15.47 vs. 3.55 ± 6.16 (p = .014), respectively. The mean MRSI-based TV for Stage T2b or greater and Stage T2a or less tumors was significantly different (2.23 ± 2.62 cm 3 vs. 1.26 ± 2.06 cm 3 , respectively; p = .030). This TV correlated with increased prostate-specific antigen levels (odds ratio, 1.293; p = .012). Patients with high-risk PCa had a larger TV than did the patients with intermediate-risk PCa. A similar result was found for the intermediate-risk group compared with the low-risk group (odds ratio, 1.225; p = .041). Conclusion: Biomarkers expressing the relative choline content and TV were significant parameters for the localization of PCa and could be helpful for determining the prognosis more accurately.

  20. Early Prediction of Outcome in Advanced Head-and-Neck Cancer Based on Tumor Blood Volume Alterations During Therapy: A Prospective Study

    International Nuclear Information System (INIS)

    Cao Yue; Popovtzer, Aron; Li, Diana; Chepeha, Douglas B.; Moyer, Jeffrey S.; Prince, Mark E.; Worden, Francis; Teknos, Theodoros; Bradford, Carol; Mukherji, Suresh K.; Eisbruch, Avraham

    2008-01-01

    Purpose: To assess whether alterations in tumor blood volume (BV) and blood flow (BF) during the early course of chemo-radiotherapy (chemo-RT) for head-and-neck cancer (HNC) predict treatment outcome. Methods and Materials: Fourteen patients receiving concomitant chemo-RT for nonresectable, locally advanced HNC underwent dynamic contrast-enhanced (DCE) MRI scans before therapy and 2 weeks after initiation of chemo-RT. The BV and BF were quantified from DCE MRI. Preradiotherapy BV and BF, as well as their changes during RT, were evaluated separately in the primary gross tumor volume (GTV) and nodal GTV for association with outcomes. Results: At a median follow-up of 10 months (range, 5-27 months), 9 patients had local-regional controlled disease. One patient had regional failure, 3 had local failures, and 1 had local-regional failure. Reduction in tumor volume after 2 weeks of chemo-RT did not predict for local control. In contrast, the BV in the primary GTV after 2 weeks of chemo-RT was increased significantly in the local control patients compared with the local failure patients (p < 0.03). Conclusions: Our data suggest that an increase in available primary tumor blood for oxygen extraction during the early course of RT is associated with local control, thus yielding a predictor with potential to modify treatment. These findings require validation in larger studies

  1. Semiautomatic methods for segmentation of the proliferative tumour volume on sequential FLT PET/CT images in head and neck carcinomas and their relation to clinical outcome

    Energy Technology Data Exchange (ETDEWEB)

    Arens, Anne I.J.; Grootjans, Willem; Oyen, Wim J.G.; Visser, Eric P. [Radboud University Medical Center, Department of Nuclear Medicine, P.O. Box 9101, Nijmegen (Netherlands); Troost, Esther G.C. [Radboud University Medical Center, Department of Radiation Oncology, Nijmegen (Netherlands); Maastricht University Medical Centre, MAASTRO clinic, GROW School for Oncology and Developmental Biology, Maastricht (Netherlands); Hoeben, Bianca A.W.; Bussink, Johan; Kaanders, Johannes H.A.M. [Radboud University Medical Center, Department of Radiation Oncology, Nijmegen (Netherlands); Lee, John A.; Gregoire, Vincent [St-Luc University Hospital, Department of Radiation Oncology, Universite Catholique de Louvain, Brussels (Belgium); Hatt, Mathieu; Visvikis, Dimitris [Laboratoire de Traitement de l' Information Medicale (LaTIM), INSERM UMR1101, Brest (France)

    2014-05-15

    Radiotherapy of head and neck cancer induces changes in tumour cell proliferation during treatment, which can be depicted by the PET tracer {sup 18}F-fluorothymidine (FLT). In this study, three advanced semiautomatic PET segmentation methods for delineation of the proliferative tumour volume (PV) before and during (chemo)radiotherapy were compared and related to clinical outcome. The study group comprised 46 patients with 48 squamous cell carcinomas of the head and neck, treated with accelerated (chemo)radiotherapy, who underwent FLT PET/CT prior to treatment and in the 2nd and 4th week of therapy. Primary gross tumour volumes were visually delineated on CT images (GTV{sub CT}). PVs were visually determined on all PET scans (PV{sub VIS}). The following semiautomatic segmentation methods were applied to sequential PET scans: background-subtracted relative-threshold level (PV{sub RTL}), a gradient-based method using the watershed transform algorithm and hierarchical clustering analysis (PV{sub W} and {sub C}), and a fuzzy locally adaptive Bayesian algorithm (PV{sub FLAB}). Pretreatment PV{sub VIS} correlated best with PV{sub FLAB} and GTV{sub CT}. Correlations with PV{sub RTL} and PV{sub W} and {sub C} were weaker although statistically significant. During treatment, the PV{sub VIS}, PV{sub W} and {sub C} and PV{sub FLAB} significant decreased over time with the steepest decline over time for PV{sub FLAB}. Among these advanced segmentation methods, PV{sub FLAB} was the most robust in segmenting volumes in the third scan (67 % of tumours as compared to 40 % for PV{sub W} and {sub C} and 27 % for PV{sub RTL}). A decrease in PV{sub FLAB} above the median between the pretreatment scan and the scan obtained in the 4th week was associated with better disease-free survival (4 years 90 % versus 53 %). In patients with head and neck cancer, FLAB proved to be the best performing method for segmentation of the PV on repeat FLT PET/CT scans during (chemo)radiotherapy. This may

  2. Coil Optimization for HTS Machines

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Jensen, Bogi Bech; Abrahamsen, Asger Bech

    An optimization approach of HTS coils in HTS synchronous machines (SM) is presented. The optimization is aimed at high power SM suitable for direct driven wind turbines applications. The optimization process was applied to a general radial flux machine with a peak air gap flux density of ~3T...... is suitable for which coil segment is presented. Thus, the performed study gives valuable input for the coil design of HTS machines ensuring optimal usage of HTS tapes....

  3. Transcranial magnetic stimulation: Improved coil design for deep brain investigation

    Science.gov (United States)

    Crowther, L. J.; Marketos, P.; Williams, P. I.; Melikhov, Y.; Jiles, D. C.; Starzewski, J. H.

    2011-04-01

    This paper reports on a design for a coil for transcranial magnetic stimulation. The design shows potential for improving the penetration depth of the magnetic field, allowing stimulation of subcortical structures within the brain. The magnetic and induced electric fields in the human head have been calculated with finite element electromagnetic modeling software and compared with empirical measurements. Results show that the coil design used gives improved penetration depth, but also indicates the likelihood of stimulation of additional tissue resulting from the spatial distribution of the magnetic field.

  4. Large superconducting coil fabrication development

    International Nuclear Information System (INIS)

    Brown, R.L.; Allred, E.L.; Anderson, W.C.; Burn, P.B.; Deaderick, R.I.; Henderson, G.M.; Marguerat, E.F.

    1975-01-01

    Toroidal fields for some fusion devices will be produced by an array of large superconducting coils. Their size, space limitation, and field requirements dictate that they be high performance coils. Once installed, accessibility for maintenance and repairs is severely restricted; therefore, good reliability is an obvious necessity. Sufficient coil fabrication will be undertaken to develop and test methods that are reliable, fast, and economical. Industrial participation will be encouraged from the outset to insure smooth transition from development phases to production phases. Initially, practice equipment for three meter bore circular coils will be developed. Oval shape coil forms will be included in the practice facility later. Equipment that is more automated will be developed with the expectation of winding faster and obtaining good coil quality. Alternate types of coil construction, methods of winding and insulating, will be investigated. Handling and assembly problems will be studied. All technology developed must be feasible for scaling up when much larger coils are needed. Experimental power reactors may need coils having six meter or larger bores

  5. Techniques For Microfabricating Coils For Microelectromechanical Systems Applications

    International Nuclear Information System (INIS)

    Woods, R. C.; Powell, A. L.

    2008-01-01

    The advanced technology necessary for building future space exploration vehicles includes microfabricated coils for making possible self-inductances integrated with other passive and active electronic components. Integrated inductances make possible significant improvements in reliability over the traditional arrangement of using external discrete inductances, as well as allowing significant size (volume) reductions (also important in space vehicles). Two possible fabrication techniques (one using proprietary branded 'Foturan' glass, the other using silicon wafer substrates) for microscopic coils are proposed, using electroplating into channels. The techniques have been evaluated for fabricating the planar electrical coils needed for typical microelectromechanical systems applications. There remain problems associated with processing using 'Foturan' glass, but coil fabrication on silicon wafers was successful. Fabrication methods such as these are expected to play an important part in the development of systems and subsystems for forthcoming space exploration missions

  6. Quantification of gross tumour volume changes between simulation and first day of radiotherapy for patients with locally advanced malignancies of the lung and head/neck.

    Science.gov (United States)

    Kishan, Amar U; Cui, Jing; Wang, Pin-Chieh; Daly, Megan E; Purdy, James A; Chen, Allen M

    2014-10-01

    To quantify changes in gross tumour volume (GTV) between simulation and initiation of radiotherapy in patients with locally advanced malignancies of the lung and head/neck. Initial cone beam computed tomography (CT) scans from 12 patients with lung cancer and 12 with head/neck cancer (head and neck squamous cell carcinoma (HNSCC)) treated with intensity-modulated radiotherapy with image guidance were rigidly registered to the simulation CT scans. The GTV was demarcated on both scans. The relationship between percent GTV change and variables including time interval between simulation and start, tumour (T) stage, and absolute weight change was assessed. For lung cancer patients, the GTV increased a median of 35.06% (range, -16.63% to 229.97%) over a median interval of 13 days (range, 7-43), while for HNSCC patients, the median GTV increase was 16.04% (range, -8.03% to 47.41%) over 13 days (range, 7-40). These observed changes are statistically significant. The magnitude of this change was inversely associated with the size of the tumour on the simulation scan for lung cancer patients (P lung cancer cases) did not correlate with degree of GTV change (P > 0.1). While the observed changes in GTV were moderate from the time of simulation to start of radiotherapy, these findings underscore the importance of image guidance for target localisation and verification, particularly for smaller tumours. Minimising the delay between simulation and treatment initiation may also be beneficial. © 2014 The Royal Australian and New Zealand College of Radiologists.

  7. The coiled coil motif in polymer drug delivery systems

    Czech Academy of Sciences Publication Activity Database

    Pechar, Michal; Pola, Robert

    2013-01-01

    Roč. 31, č. 1 (2013), s. 90-96 ISSN 0734-9750 R&D Projects: GA ČR GA203/08/0543; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505 Keywords : coiled coil * hydrophilic polymer * recombinant protein Subject RIV: CD - Macromolecular Chemistry Impact factor: 8.905, year: 2013

  8. Materials and methods for higher performance screen-printed flexible MRI receive coils.

    Science.gov (United States)

    Corea, Joseph R; Lechene, P Balthazar; Lustig, Michael; Arias, Ana C

    2017-08-01

    To develop methods for characterizing materials used in screen-printed MRI coils and improve signal-to-noise ratio (SNR) with new lower-loss materials. An experimental apparatus was created to characterize dielectric properties of plastic substrates used in receive coils. Coils were fabricated by screen printing conductive ink onto several plastic substrates. Unloaded and sample loaded quality factor (Q Unloaded /Q Loaded ) measurements and scans on a 3T scanner were used to characterize coil performance. An experimental method was developed to describe the relationship between a coil's Q Unloaded and the SNR it provides in images of a phantom. In addition, 3T scans of a phantom and the head of a volunteer were obtained with a proof-of-concept printed eight-channel array, and the results were compared with a commercial 12-channel array. Printed coils with optimized substrates exhibited up to 97% of the image SNR when compared with a traditional coil on a loading phantom. Q Unloaded and the SNR of coils were successfully correlated. The printed array resulted in images comparable to the quality given by the commercial array. Using the proposed methods and materials, the SNR of printed coils approached that of commercial coils while using a new fabrication technique that provided more flexibility and close contact with the patient's body. Magn Reson Med 78:775-783, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  9. Sequentially delivered boost plans are superior to simultaneously delivered plans in head and neck cancer when the boost volume is located further away from the parotid glands

    International Nuclear Information System (INIS)

    Lamers-Kuijper, Emmy; Heemsbergen, Wilma; Mourik, Anke van; Rasch, Coen

    2011-01-01

    Purpose: To find parameters that predict which head and neck patients benefit from a sequentially delivered boost treatment plan compared to a simultaneously delivered plan, with the aim to spare the salivary glands. Methods and materials: We evaluated 50 recently treated head and neck cancer patients. Apart from the clinical plan with a sequentially (SEQ) given boost using an Intensity Modulated Radiotherapy Technique (IMRT), a simultaneous integrated boost (SIB) technique plan was constructed with the same beam set-up. The mean dose to the parotid glands was calculated and compared. The elective nodal areas were bilateral in all cases, with a boost on either one side or both sides of the neck. Results: When the parotid gland volume and the Planning Target Volume (PTV) for the boost overlap there is on average a lower dose to the parotid gland with a SIB technique (-1.2 Gy), which is, however, not significant (p = 0.08). For all parotid glands with no boost PTV overlap, there is a benefit from a SEQ technique compared to a SIB technique for the gland evaluated (on average a 2.5 Gy lower dose to the parotid gland, p < 0.001). When the distance between gland and PTV is 0-1 cm, this difference is on average 0.8 Gy, for 1-2 cm distance 2.9 Gy and for glands with a distance greater than 2 cm, 3.3 Gy. When the lymph nodes on the evaluated side are also included in the boost PTV, however, this relationship between the distance and the gain of a SEQ seems less clear. Conclusions: A sequentially delivered boost technique results in a better treatment plan for most cases, compared to a simultaneous integrated boost IMRT technique, if the boost PTV is more than 1 cm away from at least one parotid gland.

  10. Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

    Directory of Open Access Journals (Sweden)

    Oliver Weinberger

    Full Text Available The purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation.Electromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each transmission regime flip angle distributions and blood-myocardium contrast are examined in a volunteer study of 12 subjects. The feasibility of the local transceiver RF coil array for cardiac chamber quantification at 3 Tesla is demonstrated.Our simulations and experiments demonstrate that cardiac MR at 3 Tesla using four-channel surface RF coil transmission is competitive versus current clinical CMR practice of large volume body RF coil transmission. The efficiency advantage of the 4TX/4RX setup facilitates shorter repetition times governed by local SAR limits versus body RF coil transmission at whole-body SAR limit. No statistically significant difference was found for cardiac chamber quantification derived with body RF coil versus four-channel surface RF coil transmission. Our simulation also show that the body RF coil exceeds local SAR limits by a factor of ~2 when driven at maximum applicable input power to reach the whole-body SAR limit.Pursuing local surface RF coil arrays for transmission in cardiac MR is a conceptually appealing alternative to body RF coil transmission, especially for patients with implants.

  11. Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

    Science.gov (United States)

    Winter, Lukas; Dieringer, Matthias A.; Els, Antje; Oezerdem, Celal; Rieger, Jan; Kuehne, Andre; Cassara, Antonino M.; Pfeiffer, Harald; Wetterling, Friedrich; Niendorf, Thoralf

    2016-01-01

    Introduction The purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation. Methods Electromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each transmission regime flip angle distributions and blood-myocardium contrast are examined in a volunteer study of 12 subjects. The feasibility of the local transceiver RF coil array for cardiac chamber quantification at 3 Tesla is demonstrated. Results Our simulations and experiments demonstrate that cardiac MR at 3 Tesla using four-channel surface RF coil transmission is competitive versus current clinical CMR practice of large volume body RF coil transmission. The efficiency advantage of the 4TX/4RX setup facilitates shorter repetition times governed by local SAR limits versus body RF coil transmission at whole-body SAR limit. No statistically significant difference was found for cardiac chamber quantification derived with body RF coil versus four-channel surface RF coil transmission. Our simulation also show that the body RF coil exceeds local SAR limits by a factor of ~2 when driven at maximum applicable input power to reach the whole-body SAR limit. Conclusion Pursuing local surface RF coil arrays for transmission in cardiac MR is a conceptually appealing alternative to body RF coil transmission, especially for patients with implants. PMID:27598923

  12. Two-Slotted Surface Coil Array for Magnetic Resonance Imaging at 4 Tesla

    International Nuclear Information System (INIS)

    Solis, S. E.; Hernandez, J. A.; Rodriguez, A. O.; Tomasi, D.

    2008-01-01

    Arrays of antennas have been widely accepted for magnetic resonance imaging applications due to their high signal-to-noise ratio (SNR) over large volumes of interest. A new surface coil based on the magnetron tube and called slotted surface coil, has been recently introduced by our group. This coil design experimentally demonstrated a significant improvement over the circular-shaped coil when used in the receive-only mode. The slotted coils formed a two-sheet structure with a 90 deg. separation and each coil had 6 circular slots. Numerical simulations were performed using the finite element method for this coil design to study the behaviour of the array magnetic field. Then, we developed a two-coil array for brain magnetic resonance imaging to be operated at the resonant frequency of 170 MHz in the transceiver mode. Phantom images were acquired with our coil array and standard pulse sequences on a research-dedicated 4 Tesla scanner. Numerical simulations demonstrated that electromagnetic interaction between the coil elements is negligible, and that the magnetic field showed a good uniformity. In vitro images showed the feasibility of this coil array for standard pulses for high field magnetic resonance imaging

  13. Measurement of heating coil temperature for e-cigarettes with a “top-coil” clearomizer

    Science.gov (United States)

    Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A.; Kumagai, Kazukiyo

    2018-01-01

    Objectives To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a “top-coil” clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. Methods The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3–6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). Results For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such “top-coil” clearomizers. Conclusions This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full

  14. Automated volume analysis of head and neck lesions on CT scans using 3D level set segmentation

    International Nuclear Information System (INIS)

    Street, Ethan; Hadjiiski, Lubomir; Sahiner, Berkman; Gujar, Sachin; Ibrahim, Mohannad; Mukherji, Suresh K.; Chan, Heang-Ping

    2007-01-01

    The authors have developed a semiautomatic system for segmentation of a diverse set of lesions in head and neck CT scans. The system takes as input an approximate bounding box, and uses a multistage level set to perform the final segmentation. A data set consisting of 69 lesions marked on 33 scans from 23 patients was used to evaluate the performance of the system. The contours from automatic segmentation were compared to both 2D and 3D gold standard contours manually drawn by three experienced radiologists. Three performance metric measures were used for the comparison. In addition, a radiologist provided quality ratings on a 1 to 10 scale for all of the automatic segmentations. For this pilot study, the authors observed that the differences between the automatic and gold standard contours were larger than the interobserver differences. However, the system performed comparably to the radiologists, achieving an average area intersection ratio of 85.4% compared to an average of 91.2% between two radiologists. The average absolute area error was 21.1% compared to 10.8%, and the average 2D distance was 1.38 mm compared to 0.84 mm between the radiologists. In addition, the quality rating data showed that, despite the very lax assumptions made on the lesion characteristics in designing the system, the automatic contours approximated many of the lesions very well

  15. The IEA Large Coil Task

    International Nuclear Information System (INIS)

    Beard, D.S.; Klose, W.; Shimamoto, S.; Vecsey, G.

    1988-01-01

    A multinational program of cooperative research, development, demonstrations, and exchanges of information on superconducting magnets for fusion was initiated in 1977 under an IEA agreement. The first major step in the development of TF magnets was called the Large Coil Task. Participants in LCT were the U.S. DOE, EURATOM, JAERI, and the Departement Federal de l'Interieur of Switzerland. The goals of LCT were to obtain experimental data, to demonstrate reliable operation of large superconducting coils, and to prove design principles and fabrication techniques being considered for the toroidal magnets of thermonuclear reactors. These goals were to be accomplished through coordinated but largely independent design, development, and construction of six test coils, followed by collaborative testing in a compact toroidal test array at fields of 8 T and higher. Under the terms of the IEA Agreement, the United States built and operated the test facility at Oak Ridge and provided three test coils. The other participants provided one coil each. Information on design and manufacturing and all test data were shared by all. The LCT team of each participant included a government laboratory and industrial partners or contractors. The last coil was completed in 1985, and the test assembly was completed in October of that year. Over the next 23 months, the six-coil array was cooled down and extensive testing was performed. Results were gratifying, as tests achieved design-point performance and well beyond. (Each coil reached a peak field of 9 T.) Experiments elucidated coil behavior, delineated limits of operability, and demonstrated coil safety. (orig./KP)

  16. Superconducting cyclotron magnet coil short

    International Nuclear Information System (INIS)

    Mallory, M.L.; Blosser, H.G.; Clark, D.J.; Launer, H.; Lawton, D.; Miller, P.; Resmini, F.

    1982-01-01

    In February 1981, a short circuit appeared in the superconducting coil of the K500 cyclotron. The short is resistive in character and therefore has no effect on steady state operation of the magnet. The resistance of the short varies, sometimes being below threshold of detection as a heat load on the cooling system and sometimes being significant. The resistance under certain conditions shows approximately cyclic phenomena with time constants in the range of seconds and other approximately cyclic phenomena which correlate with gross operating parameters of the magnet (shifting current from one coil to another at high field and lowering and raising the liquid helium level). A number of diagnostic studies of the short have been made, using 1) an array of flux sensing loops to sense the magnetic effect of the short, 2) voltage comparisons between upper and lower sections of the coil, 3) comparisons of forces in the nine member coil support system and 4) the effect of the short on the thermal charactersitics of the coil. Insulation failure or a metal chip shorting out turns have been explored in some detail but a convincing determination of the exact cause of the short may never be available, (even the extreme step of unwinding the coil having a significant probability that an imperfection with the observed characteristics would pass unnoticed). Analysis of the characteristics of the short indicated that the most serious consequence would be failure of the coils mechanical support system in the event that the magnet was quickly discharged, as in a dump or quench. To deal with this hazard, the support system has been modified by installing solid supports which prevent the coil from moving by an amount sufficient to damage the support system. We have also reexamined the data and calculations used in the original coil design and have made some additional measurements of the properties of the materials (yield strength, friction coefficient, Young's modulus) used in the

  17. Aneurysm coil embolization: cost per volumetric filling analysis and strategy for cost reduction.

    Science.gov (United States)

    Wang, Charlie; Ching, Esteban Cheng; Hui, Ferdinand K

    2016-05-01

    One of the primary device expenditures associated with the endovascular treatment of aneurysms is that of detachable coils. Analyzing the cost efficiency of detachable coils is difficult, given the differences in design, implantable volume, and the presence of additives. However, applying a volume per cost metric may provide an index analogous to unit price found in grocery stores. The price information for 509 different coils belonging to 31 different coil lines, available as of September 2013, was obtained through the inventory management system at the study site, and normalized to the price of the least expensive coil. Values were used to calculate the logarithmic ratio of volume over cost. Operator choice among coil sizes can vary the material costs by five-fold in a hypothetical aneurysm. The difference in coil costs as a function of cost per volume of coil can vary tremendously. Using the present pricing algorithms, using the longest available length at a particular helical dimension and system yields improved efficiency. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  18. Superconducting poloidal coils for STARFIRE commercial reactor

    International Nuclear Information System (INIS)

    Wang, S.T.; Evans, K. Jr.; Turner, L.R.; Huang, Y.C.; Prater, R.; Alcorn, J.

    1979-01-01

    STARFIRE is considered to be the tenth commercial tokamak power plant. A preliminary design study on its superconducting poloidal coil system is presented. Key features of the design studies are: the elimination of the ohmic heating coil; the trade-off studies of the equilibrium field coil locations; and the development of a conceptual design for the superconducting equilibrium field coils. Described are the 100 kA cryostable conductor design, the coil structure, and evaluation of the coil forces

  19. Coil protection calculator for TFTR

    International Nuclear Information System (INIS)

    Marsala, R.J.; Lawson, J.E.; Persing, R.G.; Senko, T.R.; Woolley, R.D.

    1989-01-01

    A new coil protection system (CPS) is being developed to replace the existing TFTR magnetic coil fault detector. The existing fault detector sacrifices TFTR operating capability for simplicity. The new CPS, when installed in October of 1988, will permit operation up to the actual coil stress limits parameters in real-time. The computation will be done in a microprocessor based Coil Protection Calculator (CPC) currently under construction at PPL. THe new CPC will allow TFTR to operate with higher plasma currents and will permit the optimization of pulse repetition rates. The CPC will provide real-time estimates of critical coil and bus temperatures and stresses based on real-time redundant measurements of coil currents, coil cooling water inlet temperature, and plasma current. The critical parameter calculations are compared to prespecified limits. If these limits are reached or exceeded, protection action will be initiated to a hard wired control system (HCS), which will shut down the power supplies. The CPC consists of a redundant VME based microprocessor system which will sample all input data and compute all stress quantities every ten milliseconds. Thermal calculations will be approximated every 10ms with an exact solution occurring every second. The CPC features continuous cross-checking of redundant input signal, automatic detection of internal failure modes, monitoring and recording of calculated results, and a quick, functional verification of performance via an internal test system. (author)

  20. Heads Up

    Science.gov (United States)

    ... Connect with Us HEADS UP Apps Reshaping the Culture Around Concussion in Sports Get HEADS UP on Your Web Site Concussion ... HEADS UP on your web site! Create a culture of safety for young athletes Officials, learn how you can ... UP to Providers HEADS UP to Youth Sports HEADS UP to School Sports HEADS UP to ...

  1. Development and implementation of an 84-channel matrix gradient coil.

    Science.gov (United States)

    Littin, Sebastian; Jia, Feng; Layton, Kelvin J; Kroboth, Stefan; Yu, Huijun; Hennig, Jürgen; Zaitsev, Maxim

    2018-02-01

    Design, implement, integrate, and characterize a customized coil system that allows for generating spatial encoding magnetic fields (SEMs) in a highly-flexible fashion. A gradient coil with a high number of individual elements was designed. Dimensions of the coil were chosen to mimic a whole-body gradient system, scaled down to a head insert. Mechanical shape and wire layout of each element were optimized to increase the local gradient strength while minimizing eddy current effects and simultaneously considering manufacturing constraints. Resulting wire layout and mechanical design is presented. A prototype matrix gradient coil with 12 × 7 = 84 elements consisting of two element types was realized and characterized. Measured eddy currents are gradient strengths between 24 mT∕m and 78 mT∕m could be realized locally with maximum currents of 150 A. Initial proof-of-concept imaging experiments using linear and nonlinear encoding fields are demonstrated. A shielded matrix gradient coil setup capable of generating encoding fields in a highly-flexible manner was designed and implemented. The presented setup is expected to serve as a basis for validating novel imaging techniques that rely on nonlinear spatial encoding fields. Magn Reson Med 79:1181-1191, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  2. Comparison of the local dose of scattered radiation of a special dental - phantom and a real human head by using a Digital Volume Tomography (DVT)

    International Nuclear Information System (INIS)

    Neuwirth, J.; Hefner, A.

    2008-01-01

    Dental Radiography Digital Volume Tomography (DVT) gains more and more importance due to its possibility of three-dimensional imaging of teeth, jaw and visercoranium and the reduced radiation dose in comparison to conventional Computer Tomography (CT). Contrary to other, well documented radiographic procedures like dental panorama X-ray imaging there are no national or international guidelines or recommendations relating to DVT which regulate the designation of areas and standardize risk assessment. This study aims to assess the parameters necessary for local radiation protection in dental practices. Measurements were carried out in dental practices in order to evaluate the local dose resulting from different DVT devices. A special dental-phantom and a real human head were used in the irradiations in order to define the local dose of scattered radiation by nominal voltage. The dental-phantom was created for conventional dental panorama X-ray devices which make use of lower nominal voltages. This poses the question if the scatter performance of the special dental-phantom is comparable to a real human head and therefore applicable to the estimation of the radiation quality of a DVT when using 120 kV. The existing guidelines for dental panorama xray are analyzed and suggestions for future recommendations concerning the designation of areas and risk assessment for DVT are then deducted by comparing both sets of measurements. The results show that the special dental-phantom is absolutely suitable for the definition of the local dose resulting from the scattered radiation of a DVT. (author)

  3. Automatic skull segmentation from MR images for realistic volume conductor models of the head: Assessment of the state-of-the-art.

    Science.gov (United States)

    Nielsen, Jesper D; Madsen, Kristoffer H; Puonti, Oula; Siebner, Hartwig R; Bauer, Christian; Madsen, Camilla Gøbel; Saturnino, Guilherme B; Thielscher, Axel

    2018-03-12

    Anatomically realistic volume conductor models of the human head are important for accurate forward modeling of the electric field during transcranial brain stimulation (TBS), electro- (EEG) and magnetoencephalography (MEG). In particular, the skull compartment exerts a strong influence on the field distribution due to its low conductivity, suggesting the need to represent its geometry accurately. However, automatic skull reconstruction from structural magnetic resonance (MR) images is difficult, as compact bone has a very low signal in magnetic resonance imaging (MRI). Here, we evaluate three methods for skull segmentation, namely FSL BET2, the unified segmentation routine of SPM12 with extended spatial tissue priors, and the skullfinder tool of BrainSuite. To our knowledge, this study is the first to rigorously assess the accuracy of these state-of-the-art tools by comparison with CT-based skull segmentations on a group of ten subjects. We demonstrate several key factors that improve the segmentation quality, including the use of multi-contrast MRI data, the optimization of the MR sequences and the adaptation of the parameters of the segmentation methods. We conclude that FSL and SPM12 achieve better skull segmentations than BrainSuite. The former methods obtain reasonable results for the upper part of the skull when a combination of T1- and T2-weighted images is used as input. The SPM12-based results can be improved slightly further by means of simple morphological operations to fix local defects. In contrast to FSL BET2, the SPM12-based segmentation with extended spatial tissue priors and the BrainSuite-based segmentation provide coarse reconstructions of the vertebrae, enabling the construction of volume conductor models that include the neck. We exemplarily demonstrate that the extended models enable a more accurate estimation of the electric field distribution during transcranial direct current stimulation (tDCS) for montages that involve extraencephalic

  4. Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms.

    Science.gov (United States)

    Umeda, Yasuyuki; Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori

    2017-01-01

    This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = 0.016). The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.

  5. Comparison of the induced fields using different coil configurations during deep transcranial magnetic stimulation.

    Directory of Open Access Journals (Sweden)

    Mai Lu

    Full Text Available Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS plays a role in the study of reward and motivation mechanisms, which may be beneficial in the treatment of several neurological and psychiatric disorders. However, electric field distributions induced in the brain by deep transcranial magnetic stimulation (dTMS are still unknown. In this paper, the double cone coil, H-coil and Halo-circular assembly (HCA coil which have been proposed for dTMS have been numerically designed. The distributions of magnetic flux density, induced electric field in an anatomically based realistic head model by applying the dTMS coils were numerically calculated by the impedance method. Results were compared with that of standard figure-of-eight (Fo8 coil. Simulation results show that double cone, H- and HCA coils have significantly deep field penetration compared to the conventional Fo8 coil, at the expense of induced higher and wider spread electrical fields in superficial cortical regions. Double cone and HCA coils have better ability to stimulate deep brain subregions compared to that of the H-coil. In the mean time, both double cone and HCA coils increase risk for optical nerve excitation. Our results suggest although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality.

  6. Coil for LEAR extraction septum

    CERN Multimedia

    CERN PhotoLab

    1982-01-01

    Which way does the current flow ? This intriguing object is the coil for the LEAR extraction septum. There were two septa, first a thin one, then this one, not so thin, somewhat on the borderline between septum and bending magnet.

  7. First coil for the SC

    CERN Multimedia

    CERN PhotoLab

    1955-01-01

    The coils for the SC magnet were stored in the large hangar of the Cointrin Airport (to make sure that they would be available before snow and ice would block the roads and canals from Belgium, where they were built).

  8. Radiation resistant ducted superconductive coil

    International Nuclear Information System (INIS)

    Schleich, A.

    1976-01-01

    The radiation-resistant ducted superconductive coil consists of a helically wound electrical conductor constituted by an electrically conductive core of superconductive material provided with a longitudinally extending cooling duct. The core is covered with a layer of inorganic insulating material and the duct is covered by an electrically conductive metallic gas-tight sheath. The metallic sheaths on adjacent turns of the coil are secured together. 2 Claims, 4 Drawing Figures

  9. The Swiss LCT-coil

    International Nuclear Information System (INIS)

    Vecsey, G.; Benz, H.; Horvath, I.

    1985-01-01

    With delivery of the coil to ORNL on February 4, 1984, the second phase of the Swiss Large Coil Program - design and construction - was terminated. Mainlines of the Swiss design concept are summarized and related to theoretical calculations, experimental results of the supporting program, fabricational experience and first successful test results. An attempt is made to draw preliminary conclusions with regard to the design of future toroidal systems such as NET

  10. The SMES model coil. Fabrication

    International Nuclear Information System (INIS)

    Hanai, Satoshi; Nakamoto, Kazunari; Takahashi, Nobuji

    1998-01-01

    A SMES model coil was fabricated as R and D item in the development of component technologies for a 480 MJ/20 MW SMES pilot plant. The coil consists of four double-pancake windings. The coil is the same diameter but half the number of pancakes that will be needed for a SMES pilot plant. The NbTi cable-in-conduit conductor and superconducting joints between the double pancakes are cooled by a forced flow of supercritical helium. Prior to fabrication, various characteristics of the cable-in-conduit were measured by full-sized short samples from actual conductors and by scaled short samples from scaled conductors. The critical current of the scaled short samples was in agreement with that calculated from one strand of the conductor. The impedance between arbitrary dual-oxide coated strands in the full-size conductor was measured to be smaller than that obtained from two Cr-plated strands, which showed a good degree of stability in another coil. It was estimated that oxide-coated conductors would have high stability. Through fabrication of a model coil, it was demonstrated that a large forced-flow coil for a small-scale 100 kWh SMES device could be manufactured. (author)

  11. The SMES model coil. Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Hanai, Satoshi; Nakamoto, Kazunari; Takahashi, Nobuji [Toshiba Corp., Yokohama, Kanagawa (Japan)] [and others

    1998-07-01

    A SMES model coil was fabricated as R and D item in the development of component technologies for a 480 MJ/20 MW SMES pilot plant. The coil consists of four double-pancake windings. The coil is the same diameter but half the number of pancakes that will be needed for a SMES pilot plant. The NbTi cable-in-conduit conductor and superconducting joints between the double pancakes are cooled by a forced flow of supercritical helium. Prior to fabrication, various characteristics of the cable-in-conduit were measured by full-sized short samples from actual conductors and by scaled short samples from scaled conductors. The critical current of the scaled short samples was in agreement with that calculated from one strand of the conductor. The impedance between arbitrary dual-oxide coated strands in the full-size conductor was measured to be smaller than that obtained from two Cr-plated strands, which showed a good degree of stability in another coil. It was estimated that oxide-coated conductors would have high stability. Through fabrication of a model coil, it was demonstrated that a large forced-flow coil for a small-scale 100 kWh SMES device could be manufactured. (author)

  12. Localizing on-scalp MEG sensors using an array of magnetic dipole coils.

    Science.gov (United States)

    Pfeiffer, Christoph; Andersen, Lau M; Lundqvist, Daniel; Hämäläinen, Matti; Schneiderman, Justin F; Oostenveld, Robert

    2018-01-01

    Accurate estimation of the neural activity underlying magnetoencephalography (MEG) signals requires co-registration i.e., determination of the position and orientation of the sensors with respect to the head. In modern MEG systems, an array of hundreds of low-Tc SQUID sensors is used to localize a set of small, magnetic dipole-like (head-position indicator, HPI) coils that are attached to the subject's head. With accurate prior knowledge of the positions and orientations of the sensors with respect to one another, the HPI coils can be localized with high precision, and thereby the positions of the sensors in relation to the head. With advances in magnetic field sensing technologies, e.g., high-Tc SQUIDs and optically pumped magnetometers (OPM), that require less extreme operating temperatures than low-Tc SQUID sensors, on-scalp MEG is on the horizon. To utilize the full potential of on-scalp MEG, flexible sensor arrays are preferable. Conventional co-registration is impractical for such systems as the relative positions and orientations of the sensors to each other are subject-specific and hence not known a priori. Herein, we present a method for co-registration of on-scalp MEG sensors. We propose to invert the conventional co-registration approach and localize the sensors relative to an array of HPI coils on the subject's head. We show that given accurate prior knowledge of the positions of the HPI coils with respect to one another, the sensors can be localized with high precision. We simulated our method with realistic parameters and layouts for sensor and coil arrays. Results indicate co-registration is possible with sub-millimeter accuracy, but the performance strongly depends upon a number of factors. Accurate calibration of the coils and precise determination of the positions and orientations of the coils with respect to one another are crucial. Finally, we propose methods to tackle practical challenges to further improve the method.

  13. Equilibrium field coil concepts for INTOR

    International Nuclear Information System (INIS)

    Strickler, D.J.; Peng, Y.K.M.; Brown, T.G.

    1981-08-01

    Methods are presented for reducing ampere-turn requirements in the EF coil system. It is shown that coil currents in an EF coil system external to the toroidal field coils can be substantially reduced by relaxing the triangularity of a D-shaped plasma. Further reductions are realized through a hybrid EF coil system using both internal and external coils. Equilibrium field coils for a poloidally asymmetric, single-null INTOR configuration are presented. It is shown that the shape of field lines in the plasma scrapeoff region and divertor channel improves as triangularity is reduced, but it does so at the possible expense of achievable stable beta values

  14. In vivo portal dosimetry for head-and-neck VMAT and lung IMRT: Linking γ-analysis with differences in dose–volume histograms of the PTV

    International Nuclear Information System (INIS)

    Rozendaal, Roel Arthur; Mijnheer, Ben J.; Herk, Marcel van; Mans, Anton

    2014-01-01

    Purpose: To relate the results of γ-analysis and dose–volume histogram (DVH) analysis of the PTV for detecting dose deviations with in vivo dosimetry for two treatment sites. Methods and materials: In vivo 3D dose distributions were reconstructed for 722 fractions of 200 head-and-neck (H and N) VMAT treatments and 183 fractions of 61 lung IMRT plans. The reconstructed and planned dose distributions in the PTV were compared using (a) the γ-distribution and (b) the differences in D2, D50 and D98 between the two dose distributions. Using pre-defined tolerance levels, all fractions were classified as deviating or not deviating by both methods. The mutual agreement, the sensitivity and the specificity of the two methods were compared. Results: For lung IMRT, the classification of the fractions was nearly identical for γ- and DVH-analyses of the PTV (94% agreement) and the sensitivity and specificity were comparable for both methods. Less agreement (80%) was found for H and N VMAT, while γ-analysis was both less sensitive and less specific. Conclusions: DVH- and γ-analyses perform nearly equal in finding dose deviations in the PTV for lung IMRT treatments; for H and N VMAT treatments, DVH-analysis is preferable. As a result of this study, a smooth transition to using DVH-analysis clinically for detecting in vivo dose deviations in the PTV is within reach

  15. Skin Cancer of the Head and Neck With Perineural Invasion: Defining the Clinical Target Volumes Based on the Pattern of Failure

    International Nuclear Information System (INIS)

    Gluck, Iris; Ibrahim, Mohannad; Popovtzer, Aron; Teknos, Theodoros N.; Chepeha, Douglas B.; Prince, Mark E.; Moyer, Jeffrey S.; Bradford, Carol R.; Eisbruch, Avraham

    2009-01-01

    Purpose: To analyze patterns of failure in patients with head-and-neck cutaneous squamous cell carcinoma (HNCSCC) and clinical/radiologic evidence of perineural invasion (CPNI), in order to define neural clinical target volume (CTV) for treatment planning. Methods and Materials: Patients treated with three-dimensional (3D) conformal or intensity-modulated radiotherapy (IMRT) for HNCSCC with CPNI were included in the study. A retrospective review of the clinical charts, radiotherapy (RT) plans and radiologic studies has been conducted. Results: Eleven consecutive patients with HNCSCCs with CPNI were treated from 2000 through 2007. Most patients underwent multiple surgical procedures and RT courses. The most prevalent failure pattern was along cranial nerves (CNs), and multiple CNs were ultimately involved in the majority of cases. In all cases the involved CNs at recurrence were the main nerves innervating the primary tumor sites, as well as their major communicating nerves. We have found several distinct patterns of disease spread along specific CNs depending on the skin regions harboring the primary tumors, including multiple branches of CN V and VII. These patterns and the pertinent anatomy are detailed in the this article. Conclusions: Predictable disease spread patterns along cranial nerves supplying the primary tumor sites were found in this study. Awareness of these patterns, as well as knowledge of the relevant cranial nerve anatomy, should be the basis for CTV definition and delineation for RT treatment planning.

  16. Endovascular rescue method for undesirably stretched coil.

    Science.gov (United States)

    Cho, Jae Hoon

    2014-10-01

    Undesirable detachment or stretching of coils within the parent artery during aneurysm embolization can be related with thrombus formation, which can be caused occlusion of parent artery or embolic event(s). To escape from this situation, several rescue methods have been reported. A case with undesirably stretched coil in which another rescue method was used, is presented. When the stretched coil is still located in the coil delivery microcatheter, the stretched coil can be removed safely using a snare and a handmade monorail microcatheter. After a snare is lodged in the handmade monorail microcatheter, the snare is introduced over the coil delivery micorcatheter and located in the distal part of the stretched coil. After then, the handmade monorail microcatheter captures the stretched coil and the snare as one unit. This technique using a handmade monorail microcatheter and a snare can be a good rescue modality for the undesirably stretched coil, still remained within the coil delivery microcatheter.

  17. Impact of coil design on the contrast-to-noise ratio, precision, and consistency of quantitative cartilage morphometry at 3 Tesla: a pilot study for the osteoarthritis initiative.

    Science.gov (United States)

    Eckstein, Felix; Kunz, Manuela; Hudelmaier, Martin; Jackson, Rebecca; Yu, Joseph; Eaton, Charles B; Schneider, Erika

    2007-02-01

    Phased-array (PA) coils generally provide higher signal-to-noise ratios (SNRs) than quadrature knee coils. In this pilot study for the Osteoarthritis Initiative (OAI) we compared these two types of coils in terms of contrast-to-noise ratio (CNR), precision, and consistency of quantitative femorotibial cartilage measurements. Test-retest measurements were acquired using coronal fast low-angle shot with water excitation (FLASHwe) and coronal multiplanar reconstruction (MPR) of sagittal double-echo steady state with water excitation (DESSwe) at 3T. The precision errors for cartilage volume and thickness were coil and coil with FLASHwe, and coil and sequence. The PA coil measurements did not always fully agree with the quadrature coil measurements, and some differences were significant. The higher CNR of the PA coil did not translate directly into improved precision of cartilage measurement; however, summing up cartilage plates within the medial and lateral compartment reduced precision errors. Copyright (c) 2007 Wiley-Liss, Inc.

  18. Coil supporting device in nuclear fusion apparatus

    International Nuclear Information System (INIS)

    Hoshi, Ryo; Imura, Yasuya.

    1974-01-01

    Object: To secure intermediate fittings with a coil fixed thereon by an insulating tape to a fixed body by means of fittings, thereby supporting the coil in a narrow space. Structure: A coil is secured to intermediate fittings by means of an insulating tape, after which the intermediate fittings is mounted on a fixed body through fittings to support the coil in a narrow clearance portion between a plasma sealed vessel and a main coil. (Kamimura, M.)

  19. Follow-up of intracranial aneurysms treated with detachable coils: comparison of 3D inflow MRA at 3T and 1.5T and contrast-enhanced MRA at 3T with DSA

    International Nuclear Information System (INIS)

    Ramgren, Birgitta; Siemund, Roger; Cronqvist, Mats; Undren, Per; Holtaas, Stig; Nilsson, Ola G.; Larsson, Elna-Marie

    2008-01-01

    The purpose of this prospective study was to compare 3T and 1.5T magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) for the follow-up of endovascular treated intracranial aneurysms to assess the grade of occlusion. Thirty-seven patients with 41 aneurysms who had undergone endovascular treatment with detachable coils were included. MRA was performed on the same day using an eight-channel sensitivity encoding head-coil with 3D axial inflow technique. At 3T, a contrast-enhanced transverse 3D fast gradient echo acquisition was also performed. Most patients underwent DSA the following day. MRA scans and DSA were classified first independently by two neuroradiologists and an interventional neuroradiologist. Secondly, a consensus was done. Source images, maximum intensity projection, multiplanar reconstruction and volume rendering reconstructions were used for MRA evaluations. A modification of the Raymond classification, previously used for DSA evaluation of recanalization, was used. Statistical comparison of the consensus showed that 3T MRA with 3D axial inflow technique had better agreement with DSA (κ = 0.43) than 1.5T MRA(κ = 0.21) and contrast-enhanced MRA (CE-MRA) at 3T (κ = 0.17). The susceptibility artefacts from the coil mesh were significally smaller at 3T (p = 0.002-0.007) than at 1.5T. 3T MRA, using a sensitivity encoding head-coil, showed better agreement with DSA than 1.5T and CE-MRA at 3T for evaluation of aneurysms treated with endovascular coiling. (orig.)

  20. A novel coil array for combined TMS/fMRI experiments at 3 T.

    Science.gov (United States)

    Navarro de Lara, Lucia I; Windischberger, Christian; Kuehne, Andre; Woletz, Michael; Sieg, Jürgen; Bestmann, Sven; Weiskopf, Nikolaus; Strasser, Bernhard; Moser, Ewald; Laistler, Elmar

    2015-11-01

    To overcome current limitations in combined transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) studies by employing a dedicated coil array design for 3 Tesla. The state-of-the-art setup for concurrent TMS/fMRI is to use a large birdcage head coil, with the TMS between the subject's head and the MR coil. This setup has drawbacks in sensitivity, positioning, and available imaging techniques. In this study, an ultraslim 7-channel receive-only coil array for 3 T, which can be placed between the subject's head and the TMS, is presented. Interactions between the devices are investigated and the performance of the new setup is evaluated in comparison to the state-of-the-art setup. MR sensitivity obtained at the depth of the TMS stimulation is increased by a factor of five. Parallel imaging with an acceleration factor of two is feasible with low g-factors. Possible interactions between TMS and the novel hardware were investigated and were found negligible. The novel coil array is safe, strongly improves signal-to-noise ratio in concurrent TMS/fMRI experiments, enables parallel imaging, and allows for flexible positioning of the TMS on the head while ensuring efficient TMS stimulation due to its ultraslim design. © 2014 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  1. In vivo field-cycling relaxometry using an insert coil for magnetic field offset.

    Science.gov (United States)

    Pine, Kerrin J; Goldie, Fred; Lurie, David J

    2014-11-01

    The T(1) of tissue has a strong dependence on the measurement magnetic field strength. T(1) -dispersion could be a useful contrast parameter, but is unavailable to clinical MR systems which operate at fixed magnetic field strength. The purpose of this work was to implement a removable insert magnet coil for field-cycling T(1) -dispersion measurements on a vertical-field MRI scanner, by offsetting the static field over a volume of interest. An insert magnet coil was constructed for use with a whole-body sized 59 milli-Tesla (mT) vertical-field, permanent-magnet based imager. The coil has diameter 38 cm and thickness 6.1 cm and a homogeneous region (± 5%) of 5 cm DSV, offset by 5 cm from the coil surface. Surface radiofrequency (RF) coils were also constructed. The insert coil was used in conjunction with a surface RF coil and a volume-localized inversion-recovery pulse sequence to plot T(1) -dispersion in a human volunteer's forearm over a range of field strengths from 1 mT to 70 mT. T(1) -dispersion measurements were demonstrated on a fixed-field MRI scanner, using an insert coil. This demonstrates the feasibility of relaxation dispersion measurements on an otherwise conventional MR imager, facilitating the exploitation of T(1) -dispersion contrast for enhanced diagnosis. Copyright © 2013 Wiley Periodicals, Inc.

  2. A compact spin-exchange optical pumping system for 3He polarization based on a solenoid coil, a VBG laser diode, and a cosine theta RF coil

    Science.gov (United States)

    Lee, Sungman; Kim, Jongyul; Moon, Myung Kook; Lee, Kye Hong; Lee, Seung Wook; Ino, Takashi; Skoy, Vadim R.; Lee, Manwoo; Kim, Guinyun

    2013-02-01

    For use as a neutron spin polarizer or analyzer in the neutron beam lines of the HANARO (High-flux Advanced Neutron Application ReactOr) nuclear research reactor, a 3He polarizer was designed based on both a compact solenoid coil and a VBG (volume Bragg grating) diode laser with a narrow spectral linewidth of 25 GHz. The nuclear magnetic resonance (NMR) signal was measured and analyzed using both a built-in cosine radio-frequency (RF) coil and a pick-up coil. Using a neutron transmission measurement, we estimated the polarization ratio of the 3He cell as 18% for an optical pumping time of 8 hours.

  3. CCHMM_PROF: a HMM-based coiled-coil predictor with evolutionary information

    DEFF Research Database (Denmark)

    Bartoli, Lisa; Fariselli, Piero; Krogh, Anders

    2009-01-01

    tools are available for predicting coiled-coil domains in protein sequences, including those based on position-specific score matrices and machine learning methods. RESULTS: In this article, we introduce a hidden Markov model (CCHMM_PROF) that exploits the information contained in multiple sequence...... alignments (profiles) to predict coiled-coil regions. The new method discriminates coiled-coil sequences with an accuracy of 97% and achieves a true positive rate of 79% with only 1% of false positives. Furthermore, when predicting the location of coiled-coil segments in protein sequences, the method reaches...

  4. Transient voltage oscillations in coils

    International Nuclear Information System (INIS)

    Chowdhuri, P.

    1985-01-01

    Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated

  5. Metabolic Tumor Volume as a Prognostic Imaging-Based Biomarker for Head-and-Neck Cancer: Pilot Results From Radiation Therapy Oncology Group Protocol 0522

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, David L., E-mail: david.schwartz@utsw.edu [Department of Radiation Oncology, University of Texas Southwestern School of Medicine, Dallas, Texas (United States); Harris, Jonathan [Radiation Therapy Oncology Group Statistical Center, Philadelphia, Pennsylvania (United States); Yao, Min [Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, Ohio (United States); Rosenthal, David I. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Opanowski, Adam; Levering, Anthony [American College of Radiology Imaging Network, Philadelphia, Pennsylvania (United States); Ang, K. Kian [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Trotti, Andy M. [Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida (United States); Garden, Adam S. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Jones, Christopher U. [Sutter Medical Group, Sacramento, California (United States); Harari, Paul [Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin (United States); Foote, Robert [Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (United States); Holland, John [Department of Radiation Medicine, Oregon Health & Science University, Portland, Oregon (United States); Zhang, Qiang [Radiation Therapy Oncology Group Statistical Center, Philadelphia, Pennsylvania (United States); Le, Quynh-Thu [Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, California (United States)

    2015-03-15

    Purpose: To evaluate candidate fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging biomarkers for head-and-neck chemoradiotherapy outcomes in the cooperative group trial setting. Methods and Materials: Radiation Therapy Oncology Group (RTOG) protocol 0522 patients consenting to a secondary FDG-PET/CT substudy were serially imaged at baseline and 8 weeks after radiation. Maximum standardized uptake value (SUVmax), SUV peak (mean SUV within a 1-cm sphere centered on SUVmax), and metabolic tumor volume (MTV) using 40% of SUVmax as threshold were obtained from primary tumor and involved nodes. Results: Of 940 patients entered onto RTOG 0522, 74 were analyzable for this substudy. Neither high baseline SUVmax nor SUVpeak from primary or nodal disease were associated with poor treatment outcomes. However, primary tumor MTV above the cohort median was associated with worse local-regional control (hazard ratio 4.01, 95% confidence interval 1.28-12.52, P=.02) and progression-free survival (hazard ratio 2.34, 95% confidence interval 1.02-5.37, P=.05). Although MTV and T stage seemed to correlate (mean MTV 6.4, 13.2, and 26.8 for T2, T3, and T4 tumors, respectively), MTV remained a strong independent prognostic factor for progression-free survival in bivariate analysis that included T stage. Primary MTV remained prognostic in p16-associated oropharyngeal cancer cases, although sample size was limited. Conclusion: High baseline primary tumor MTV was associated with worse treatment outcomes in this limited patient subset of RTOG 0522. Additional confirmatory work will be required to validate primary tumor MTV as a prognostic imaging biomarker for patient stratification in future trials.

  6. Multi-detector row CT of the head and neck: comparison of different volumes of contrast material with and without a saline chaser

    International Nuclear Information System (INIS)

    Yoon, Dae Young; You, Su Yeon; Choi, Chul Soon; Chang, Suk Ki; Yun, Eun Joo; Seo, Young Lan; Park, Sang Joon; Lee, Yu-Jin; Moon, Jeung Hee; Rho, Young-Soo; Kim, Jin-Hwan

    2006-01-01

    The aim of this study was to determine the effect of different volumes of contrast material with and without a saline chaser on tissue enhancement in multidetector row CT (MDCT) of the head and neck. In a blind prospective fashion, 120 patients were randomized into the following four groups: group 1, 80 ml contrast material administered at a flow rate of 2.0 ml/s; group 2, 80 ml followed by 40 ml saline at 2.0 ml/s; group 3, 60 ml at 1.5 ml/s; and group 4, 60 ml followed by 30 ml saline at 1.5 ml/s. The attenuation values of the carotid artery, internal jugular vein, and muscle were measured at an interval of 1.5 s in each patient. The degree of perivenous artifacts was subjectively assessed. Mean attenuation values in the carotid artery and internal jugular vein were significantly higher in groups 1 and 2 than in groups 3 and 4. The width of the diagnostic window (both carotid and jugular enhancement >150 HU) were significantly longer in groups 1 and 2 than in groups 3 and 4. The addition of a saline chaser did not result in improved vascular enhancement or a wider diagnostic window, but reduced perivenous artifacts, compared with using contrast material alone. Reduction of contrast material from 80 to 60 ml results in insufficient enhancement of neck vessels. In addition, the benefit of a saline chaser technique is not obvious except for its ability to reduce perivenous artifacts. (orig.)

  7. Large coil program support structure conceptual design

    International Nuclear Information System (INIS)

    Litherland, P.S.

    1977-01-01

    The purpose of the Large Coil Program (LCP) is to perform tests on both pool boiling and force cooled superconducting toroidal field coils. The tests will attempt to approximate conditions anticipated in an ignition tokamak. The test requirements resulted in a coil support design which accommodates up to six (6) test coils and is mounted to a structure capable of resisting coil interactions. The steps leading to the present LCP coil support structure design, details on selected structural components, and the basic assembly sequence are discussed

  8. Cooling device of superconducting coils

    International Nuclear Information System (INIS)

    Duthil, R.; Lottin, J.C.

    1985-01-01

    This device is rotating around an horizontal axis. The superconducting coils are contained in a cryogenic enclosure feeded in liquid helium forced circulation. They are related to an electric generator by electric mains each of them comprising a gas exchanger, and an exchanger-evaporator set between the cryogenic device and those exchangers. The exchanger-evaporator is aimed at dissipating the heat arriving by conductors connected to the superconducting coils. According to the invention, the invention includes an annular canalization with horizontal axis in which the connection conductors bathe in liquid helium [fr

  9. Comprehensive Survey on Improved Focality and Penetration Depth of Transcranial Magnetic Stimulation Employing Multi-Coil Arrays

    Directory of Open Access Journals (Sweden)

    Xile Wei

    2017-11-01

    Full Text Available Multi-coil arrays applied in transcranial magnetic stimulation (TMS are proposed to accurately stimulate brain tissues and modulate neural activities by an induced electric field (EF. Composed of numerous independently driven coils, a multi-coil array has alternative energizing strategies to evoke EFs targeting at different cerebral regions. To improve the locating resolution and the stimulating focality, we need to fully understand the variation properties of induced EFs and the quantitative control method of the spatial arrangement of activating coils, both of which unfortunately are still unclear. In this paper, a comprehensive analysis of EF properties was performed based on multi-coil arrays. Four types of planar multi-coil arrays were used to study the relationship between the spatial distribution of EFs and the structure of stimuli coils. By changing coil-driven strategies in a basic 16-coil array, we find that an EF induced by compactly distributed coils decays faster than that induced by dispersedly distributed coils, but the former has an advantage over the latter in terms of the activated brain volume. Simulation results also indicate that the attenuation rate of an EF induced by the 36-coil dense array is 3 times and 1.5 times greater than those induced by the 9-coil array and the 16-coil array, respectively. The EF evoked by the 36-coil dispense array has the slowest decay rate. This result demonstrates that larger multi-coil arrays, compared to smaller ones, activate deeper brain tissues at the expense of decreased focality. A further study on activating a specific field of a prescribed shape and size was conducted based on EF variation. Accurate target location was achieved with a 64-coil array 18 mm in diameter. A comparison between the figure-8 coil, the planar array, and the cap-formed array was made and demonstrates an improvement of multi-coil configurations in the penetration depth and the focality. These findings suggest

  10. Comprehensive Survey on Improved Focality and Penetration Depth of Transcranial Magnetic Stimulation Employing Multi-Coil Arrays.

    Science.gov (United States)

    Wei, Xile; Li, Yao; Lu, Meili; Wang, Jiang; Yi, Guosheng

    2017-11-14

    Multi-coil arrays applied in transcranial magnetic stimulation (TMS) are proposed to accurately stimulate brain tissues and modulate neural activities by an induced electric field (EF). Composed of numerous independently driven coils, a multi-coil array has alternative energizing strategies to evoke EFs targeting at different cerebral regions. To improve the locating resolution and the stimulating focality, we need to fully understand the variation properties of induced EFs and the quantitative control method of the spatial arrangement of activating coils, both of which unfortunately are still unclear. In this paper, a comprehensive analysis of EF properties was performed based on multi-coil arrays. Four types of planar multi-coil arrays were used to study the relationship between the spatial distribution of EFs and the structure of stimuli coils. By changing coil-driven strategies in a basic 16-coil array, we find that an EF induced by compactly distributed coils decays faster than that induced by dispersedly distributed coils, but the former has an advantage over the latter in terms of the activated brain volume. Simulation results also indicate that the attenuation rate of an EF induced by the 36-coil dense array is 3 times and 1.5 times greater than those induced by the 9-coil array and the 16-coil array, respectively. The EF evoked by the 36-coil dispense array has the slowest decay rate. This result demonstrates that larger multi-coil arrays, compared to smaller ones, activate deeper brain tissues at the expense of decreased focality. A further study on activating a specific field of a prescribed shape and size was conducted based on EF variation. Accurate target location was achieved with a 64-coil array 18 mm in diameter. A comparison between the figure-8 coil, the planar array, and the cap-formed array was made and demonstrates an improvement of multi-coil configurations in the penetration depth and the focality. These findings suggest that there is a

  11. Performance of long J-shaped coils in large and giant intracranial aneurysms: an in vitro study

    International Nuclear Information System (INIS)

    Tokunaga, K.; Tanaka, N.; Sugiu, K.; Levrier, O.; Martin, J.B.; Ruefenacht, D.A.

    2002-01-01

    We evaluated the performance of long straight coils (Detach-18 trademark J-shaped coils) in large and giant in-vitro aneurysms. The coils consisted of a distal semicircular part 7 or 15 mm in diameter and a proximal 70 cm straight part having three types of stiffness: soft, standard, and stiff. We first investigated the ease of passage through a microcatheter in a realistic cerebral vessel model. Second, we made silicone models simulating lateral-type aneurysms of various spherical dome diameters (12, 15, 20 and 30 mm) and neck sizes (3-10 mm; dome-to-neck ratio approximately 3:1) and connected them to a pulsating circulatory pump. We evaluated the anchoring and folding patterns of the coils, stability of the microcatheter and coils in the aneurysm, and smoothness of delivery and retrieval of coils. Third, we compared the conformability of a coil in a large, irregular aneurysm with that of a spiral coil. The long J-shaped coils were easily advanced and retrieved through a microcatheter in a tortuous vessel model. In 12 mm spherical aneurysms, each coil made a complex framework, and knot formation or damage to the coil during withdrawal was often observed. In 15 mm aneurysms, the coils were all easily delivered and retrieved; standard-stiffness coils adapted best to this size. In 20 mm aneurysms, frameworks were less complex but still good with a standard or stiff coil, but those with soft coil were unstable and changed significantly within 3 min of detachment due to gravity and pulsatile flow. In 30 mm aneurysms, soft coils filled only the lower part during introduction, whereas a stiff coil still made a favourable framework. Conformability of a long J-shaped coil was superior to that of a spiral coil in a large, irregular aneurysm. Long J-shaped coils conform well to various configurations of large and giant aneurysms and can shorten procedures since a larger implant volume can be delivered with a single coil. Their principle of action may promote more favourable

  12. Large Coil Program magnetic system design study

    International Nuclear Information System (INIS)

    Moses, S.D.; Johnson, N.E.

    1977-01-01

    The primary objective of the Large Coil Program (LCP) is to demonstrate the reliable operation of large superconducting coils to provide a basis for the design principles, materials, and fabrication techniques proposed for the toroidal magnets for the THE NEXT STEP (TNS) and other future tokamak devices. This paper documents a design study of the Large Coil Test Facility (LCTF) in which the structural response of the Toroidal Field (TF) Coils and the supporting structure was evaluated under simulated reactor conditions. The LCP test facility structural system consists of six TF Coils, twelve coil-to-coil torsional restraining beams (torque rings), a central bucking post with base, and a Pulse Coil system. The NASTRAN Finite Element Structural Analysis computer Code was utilized to determine the distribution of deflections, forces, and stresses for each of the TF Coils, torque rings, and the central bucking post. Eleven load conditions were selected to represent probable test operations. Pulse Coils suspended in the bore of the test coil were energized to simulate the pulsed field environment characteristic of the TNS reactor system. The TORMAC Computer Code was utilized to develop the magnetic forces in the TF Coils for each of the eleven loading conditions examined, with or without the Pulse Coils energized. The TORMAC computer program output forces were used directly as input load conditions for the NASTRAN analyses. Results are presented which demonstrate the reliability of the LCTF under simulated reactor operating conditions

  13. Magnetic resonance imaging for radiotherapy planning of brain cancer patients using immobilization and surface coils

    Science.gov (United States)

    Hanvey, S.; Glegg, M.; Foster, J.

    2009-09-01

    This study investigated the compatibility of a head and neck immobilization device with magnetic resonance imaging (MRI). The immobilization device is used to position a patient in the same way as when receiving a computed tomography (CT) scan for radiotherapy planning and radiation treatment. The advantage of using immobilization in MR is improved accuracy in CT/MR image registration enabling greater confidence in the delineation of structures. The main practical difficulty in using an immobilization device in MRI is that physical constraints make their use incompatible with head imaging coils. Within this paper we describe a method for MR imaging of the brain which allows the use of head and neck immobilization devices. By a series of image quality tests we obtained the same or better image quality as a multi-channel head coil.

  14. Finite element coiled cochlea model

    Science.gov (United States)

    Isailovic, Velibor; Nikolic, Milica; Milosevic, Zarko; Saveljic, Igor; Nikolic, Dalibor; Radovic, Milos; Filipović, Nenad

    2015-12-01

    Cochlea is important part of the hearing system, and thanks to special structure converts external sound waves into neural impulses which go to the brain. Shape of the cochlea is like snail, so geometry of the cochlea model is complex. The simplified cochlea coiled model was developed using finite element method inside SIFEM FP7 project. Software application is created on the way that user can prescribe set of the parameters for spiral cochlea, as well as material properties and boundary conditions to the model. Several mathematical models were tested. The acoustic wave equation for describing fluid in the cochlea chambers - scala vestibuli and scala timpani, and Newtonian dynamics for describing vibrations of the basilar membrane are used. The mechanical behavior of the coiled cochlea was analyzed and the third chamber, scala media, was not modeled because it does not have a significant impact on the mechanical vibrations of the basilar membrane. The obtained results are in good agreement with experimental measurements. Future work is needed for more realistic geometry model. Coiled model of the cochlea was created and results are compared with initial simplified coiled model of the cochlea.

  15. BPX toroidal field coil design

    International Nuclear Information System (INIS)

    Heitzenvoeder, D.J.

    1992-01-01

    This paper reports on the toroidal field (TF) coil system of the Burning Plasma Experiment (BPX) which consists of (18) beryllium copper magnets arrayed in a wedged configuration with a major radius of 2.6 meters and a field strength capability on axis of 9.0 Tesla. The toroidal array is constructed from six (3)-coil modules to facilitate remote recovery in the event of a magnet failure after nuclear activation precludes hands-on servicing. The magnets are of a modified Bitter plate design with partial cases of type 316-LN stainless steel welded with Inconel 182 weld wire. The coil turn plates are fabricated from CDA C17510 beryllium copper with optimized mechanical, thermal, and electrical characteristics. joints within the turns and between turns are made by welding with C17200 filler wire. Cryogenic cooling is employed to reduce power dissipation and to enhance performance. The magnets are cooled between experimental pulses by pressurized liquid nitrogen flowing through channels in the edges of the coil turns. This arrangement makes possible one full-power pulse per hour. Electrical insulation consists of polyimide-glass sheets bonded in place with vacuum-pressure impregnated epoxy/glass

  16. Demonstration poloidal coil test facility

    International Nuclear Information System (INIS)

    Sato, Masahiko; Kawano, Katumi; Tada, Eisuke

    1989-01-01

    A new compact cryogenic cold compressor was developed by Japan Atomic Energy Research Institute (JAERI) in collaboration with Isikawajima-Harima Heavy Industries Co., Ltd. (IHI) in order to produce the supercritical helium below 4.2 K for Demonstration Poloidal Coils (DPC) which are forced-flow cooled type superconducting pulse coils. This compressor is one of key components for DPC test facility. The cold compressor reduces pressure in liquid helium bath, which contains liquid helium of around 3,000 l, down to 0.5 atm efficiently. Consequently, supercritical helium down to 3.5 K is produced and supplied to the DPC coils. A centrifugal compressor with dynamic gas bearing is selected as a compressor mechanism to realize high adiabatic efficiency and large flow rate. In this performance tests, the compressor was operated for 220 h at saturated condition from 0.5 to 1.0 atm without any failure. High adiabatic efficiency (more than 60 %) is achieved with wide flow range (25-65 g/s) and the design value is fully satisfied. The compressor can rotate up to 80,000 rpm at maximum then the coil supply temperature of supercritical helium is 3.5 K. (author)

  17. Open-Coil Retraction Spring

    Directory of Open Access Journals (Sweden)

    Pavankumar Janardan Vibhute

    2011-01-01

    Full Text Available Sliding mechanic has become a popular method for space closure with developments in preadjusted edgewise appliance. Furthermore, various space closing auxiliaries have been developed and evaluated extensively for their clinical efficiency. Their effectiveness enhanced with optimum force magnitude and low-load deflection rate (LDR/force decay. With the advent of NiTi springs in orthodontics, LDRs have been markedly reduced. For use of NiTi, clinician has to depend upon prefabricated closed coil springs. “Open Coil Retraction Spring (OCRS” is developed utilizing NiTi open-coil spring for orthodontic space closure. This paper describes fabrication and clinical application of OCRS which have number of advantages. It sustains low LDR with optimum force magnitude. Its design is adjustable for desired length and force level. It is fail-safe for both activation and deactivation (i.e., it cannot be over activated, and decompression limit of open coil is also controlled by the operator, resp.. A possibility to offset the OCRS away from mucosa helps to reduce its soft-tissue impingement.

  18. Investigation of shape, position, and permeability of shielding material in quadruple butterfly coil for focused transcranial magnetic stimulation

    Science.gov (United States)

    Rastogi, Priyam; Zhang, Bowen; Tang, Yalun; Lee, Erik G.; Hadimani, Ravi L.; Jiles, David C.

    2018-05-01

    Transcranial magnetic stimulation has been gaining popularity in the therapy for several neurological disorders. A time-varying magnetic field is used to generate electric field in the brain. As the development of TMS methods takes place, emphasis on the coil design increases in order to improve focal stimulation. Ideally reduction of stimulation of neighboring regions of the target area is desired. This study, focused on the improvement of the focality of the Quadruple Butterfly Coil (QBC) with supplemental use of different passive shields. Parameters such as shape, position and permeability of the shields have been explored to improve the focus of stimulation. Results have been obtained with the help of computer modelling of a MRI derived heterogeneous head model over the vertex position and the dorsolateral prefrontal cortex position using a finite element tool. Variables such as maximum electric field induced on the grey matter and scalp, volume and area of stimulation above half of the maximum value of electric field on the grey matter, and ratio of the maximum electric field in the brain versus the scalp have been investigated.

  19. PDX toroidal field coils stress analysis

    International Nuclear Information System (INIS)

    Nikodem, Z.D.; Smith, R.A.

    1975-01-01

    A method used in the stress analysis of the PDX toroidal field coil is developed. A multilayer coil design of arbitrary dimensions in the shape of either a circle or an oval is considered. The analytical model of the coil and the supporting coil case with connections to the main support structure is analyzed using the finite element technique. The three dimensional magnetic fields and the non-uniform body forces which are a loading condition on a coil due to toroidal and poloidal fields are calculated. The method of analysis permits rapid and economic evaluations of design changes in coil geometry as well as in coil support structures. Some results pertinent to the design evolution and their comparison are discussed. The results of the detailed stress analysis of the final coil design due to toroidal field, poloidal field and temperature loads are presented

  20. MRI with microscopy coil of the proximal interphalangeal joints: preliminary study

    International Nuclear Information System (INIS)

    Liu Min; Sun Haixing; Liu Dimin; Hu Meiyu; Pan Shunping; Wang Ping; Huang Xiaoling; Men Quanfei; Chen Yingming

    2009-01-01

    Objective: To investigate the use of a microscopy coil in MR examination of proximal interphalangeal joints (PIJ) to collect evidence on micro-anatomical pathological changes for further MR diagnosis. Methods: Four PIJ in cadaver and 12 PIJ from 7 normal volunteers were scanned with a microscopy surface coil (23 mm in diameter) at 1.5 T MRI. Sagittal T 1 -weighted images were also obtained with a conventional surface coil using the same parameters for the volunteers. Based on the observation of sagittal, traverse, coronal PIJ imaging features of cadaver, the optimized sequences were chosen for the volunteer's application. Image quality of the PIJ structures from volunteers was analyzed by two radiologists on a 5-point scale (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) and compared with Wilcoxon signed tank test between the microscopy and C3 surface coil in sagittal direction. Results: With microscopy coil all sequences can visualize the main structures of PI J, and all the PIJ images were classified as good or excellent except for one as average, while all the 12 PIJ with C3 coil were classified as poor or invisible. PIJ structures (proximal phalanx head, middle phalanx base, cartilage, volar plate) from volunteers show higher scores of quality with microscopy coils than those with C3 coil, and the difference was significant (Z =-3.274, -3.274, -3.213, and -3.742 respectively, all P<0.01). Conclusion: High-resolution MRI of the normal PIJ with microscopy coil was superior to those with a conventional surface coil, and it can be a promising method to diagnose interphalangeal joints lesions. (authors)

  1. A 25 kA, 2T, 78 kJ, 52 litre superconducting test coil. Strength calculations and construction

    NARCIS (Netherlands)

    ten Kate, Herman H.J.; Holtslag, A.H.M.; Knoben, J.; Steffens, H.A.; van de Klundert, L.J.M.

    1983-01-01

    Within the scope of our research program for a 25 kA superconducting rectifier, we have built a 25 kA s.c. coil being a single layer solenoid with a bore of 0.45 meter and a volume of 52 litre. The starting point for the design was to avoid any metallic structural material. This unique coil consists

  2. Bow-shaped toroidal field coils

    International Nuclear Information System (INIS)

    Bonanos, P.

    1981-05-01

    Design features of Bow-Shaped Toroidal Field Coils are described and compared with circular and D shaped coils. The results indicate that bow coils can produce higher field strengths, store more energy and be made demountable. The design offers the potential for the production of ultrahigh toroidal fields. Included are representative coil shapes and their engineering properties, a suggested structural design and an analysis of a specific case

  3. Design and modelling of a SMES coil

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Weijia; Campbell, A M; Coombs, T A, E-mail: wy215@cam.ac.u [EPEC Superconductivity group, Engineering Department, 9 JJ Thomson Avenue, Cambridge, CB3 0FA (United Kingdom)

    2010-06-01

    The design of a Superconducting Magnetic Energy Storage (SMES) coil wound by coated conductors has been presented. Based on an existing model for coated conductor pancake coils, this paper analysed the magnetic field and current density distribution of the coil at two different operation temperatures, 77K and 22K. A comparison table of the critical currents and AC losses at these two temperatures has been presented. Several steps to improve the transport current of the coil have been suggested as well.

  4. Plasmodium vivax antigen discovery based on alpha-helical coiled coil protein motif

    DEFF Research Database (Denmark)

    Céspedes, Nora; Habel, Catherine; Lopez-Perez, Mary

    2014-01-01

    Protein α-helical coiled coil structures that elicit antibody responses, which block critical functions of medically important microorganisms, represent a means for vaccine development. By using bioinformatics algorithms, a total of 50 antigens with α-helical coiled coil motifs orthologous to Pla...

  5. Sensitive quench detection of the HTS coil using a co-winding coil

    International Nuclear Information System (INIS)

    Takagi, Tomohiro; Ariyama, Takahiro; Takao, Tomoaki; Tsukamoto, Osami

    2017-01-01

    The authors have studied the co-winding coil method (CW method) using the co-wound coil electrically insulated from the HTS coil. In this method, the quench is detected by the voltage difference between the coil of the HTS tape (HTS coil) and the coil of the normal conductor (CW coil). The voltage induced in the CW coil caused by the change of the magnetic field is almost the same as that in the HTS coil because the coils are magnetically coupled close to each other. Therefore, it is expected that the induced voltage will be canceled with high accuracy and that the resistive voltage in the HTS coil will be detected with greater sensitivity compared to the bridge balance method, which is used commonly. In this study, quench detection applying the CW method is demonstrated using an experimental double-pancake coil. A tape with the copper layer deposited on the polymer substrate was used as the insulated conductor wire to form the CW coil. An additional pancake coil was used to expose the experimental double-pancake coil to the external magnetic field asymmetrically. It was shown that the CW method can detect the resistive voltage with greater sensitivity even when the HTS coil was exposed to the changing asymmetric external magnetic field. (author)

  6. An induction heating device using planar coil with high amplitude alternating magnetic fields for magnetic hyperthermia.

    Science.gov (United States)

    Wu, Zuhe; Zhuo, Zihang; Cai, Dongyang; Wu, Jian'an; Wang, Jie; Tang, Jintian

    2015-01-01

    Induction heating devices using the induction coil and magnetic nanoparticles (MNPs) are the way that the magnetic hyperthermia is heading. To facilitate the induction heating of in vivo magnetic nanoparticles in hyperthermia experiments on large animals. An induction heating device using a planar coil was designed with a magnetic field frequency of 328 kHz. The coil's magnetic field distribution and the device's induction heating performance on different concentrations of magnetic nanoparticles were measured. The alternating magnetic field produced in the axis position 165 mm away from the coil center is 40 Gs in amplitude; magnetic nanoparticles with a concentration higher than 80 mg. mL-1 can be heated up rapidly. Our results demonstrate that the device can be applied not only to in vitro and in small animal experiments of magnetic hyperthermia using MNPs, but also in large animal experiments.

  7. Status of the Swiss LCT-coil

    International Nuclear Information System (INIS)

    Zichy, J; Benz, H.; Horvath, I.; Jakob, B.; Marinucci, C.; Vecsey, G.; Weymuth, P.; Zellweger, J.

    1983-01-01

    The Swiss coil is a forced flow coil cooled by supercritical helium. A brief review of the design considerations, some of its specific features, and the progress in fabrication are described. A discussion of both the instrumentation and the cryogenic characteristics of the coil is presented

  8. Linear motor coil assembly and linear motor

    NARCIS (Netherlands)

    2009-01-01

    An ironless linear motor (5) comprising a magnet track (53) and a coil assembly (50) operating in cooperation with said magnet track (53) and having a plurality of concentrated multi-turn coils (31 a-f, 41 a-d, 51 a-k), wherein the end windings (31E) of the coils (31 a-f, 41 a-e) are substantially

  9. Split Coil Forms for Rotary Transformers

    Science.gov (United States)

    Mclyman, C. W. T.

    1982-01-01

    Split cores for rotor and stator windings of rotary transformer mounted around their respective coils (which are in bobbins) and cemented together. This arrangement simplifies winding of stator coil to go in a slot in inner diameter of stator coil. One practical application of rotary transformers fabricated according to this technique is for centrifuges, in which conventional sliprings are of uncertain reliability.

  10. Startup of large coil test facility

    International Nuclear Information System (INIS)

    Haubenreich, P.N.; Bohanan, R.E.; Fietz, W.A.; Luton, J.N.; May, J.R.

    1984-01-01

    The Large Coil Test Facility (LCTF) is being used to test superconducting toroidal field coils about one-third the size of those for INTOR. Data were obtained on performance of refrigerator, helium distribution, power supplies, controls, and data acquisition systems and on the acoustic emission, voltages, currents, and mechanical strains during charging and discharging the coils. (author)

  11. Novel method of aligning ATF-1 coils

    International Nuclear Information System (INIS)

    Rome, J.A.; Harris, J.H.; Neilson, G.H.; Jernigan, T.C.

    1983-08-01

    The coils for the Advanced Toroidal Facility (ATF-1) torsatron may be easily aligned before the machine is placed under vacuum. This is done by creating nulls in the magnetic field by energizing the coils in various configurations. All of the nulls in vertical bar B vector vertical bar occur on the z-axis. When the nulls coincide, the coils are properly aligned

  12. Self-Assembly of Rod-Coil Block Copolymers

    National Research Council Canada - National Science Library

    Jenekhe, S

    1999-01-01

    ... the self-assembly of new rod-coil diblock, rod- coil-rod triblock, and coil-rod-coil triblock copolymers from solution and the resulting discrete and periodic mesostmctares with sizes in the 100...

  13. Extended Monopole antenna Array with individual Shield (EMAS) coil: An improved monopole antenna design for brain imaging at 7 tesla MRI.

    Science.gov (United States)

    Woo, Myung-Kyun; Hong, Suk-Min; Lee, Jongho; Kang, Chang-Ki; Park, Sung-Yeon; Son, Young-Don; Kim, Young-Bo; Cho, Zang-Hee

    2016-06-01

    To propose a new Extended Monopole antenna Array with individual Shields (EMAS) coil that improves the B1 field coverage and uniformity along the z-direction. To increase the spatial coverage of Monopole antenna Array (MA) coil, each monopole antenna was shielded and extended in length. Performance of this new coil, which is referred to as EMAS coil, was compared with the original MA coil and an Extended Monopole antenna Array coil with no shield (EMA). For comparison, flip angle, signal-to-noise ratio (SNR), and receive sensitivity maps were measured at multiple regions of interest (ROIs) in the brain. The EMAS coil demonstrated substantially larger flip angle and receive sensitivity than the MA and EMA coils in the inferior aspect of the brain. In the brainstem ROI, for example, the flip angle in the EMAS coil was increased by 45.5% (or 60.0%) and the receive sensitivity was increased by 26.9% (or 14.9%), resulting in an SNR gain of 84.8% (or 76.3%) when compared with the MA coil (or EMA). The EMAS coil provided 25.7% (or 24.4%) more uniform B1+ field distribution compared with the MA (or EMA) coil in sagittal. The EMAS coil successfully extended the imaging volume in lower part of the brain. Magn Reson Med 75:2566-2572, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  14. Calculation of an axisymmetric current coil field with the bounding contour integration method

    Energy Technology Data Exchange (ETDEWEB)

    Telegin, Alexander P.; Klevets, Nickolay I. E-mail: pmsolution@mail.ru

    2004-06-01

    Method for the economic and stable (in the sense of calculation errors) analysis of an induction of a magnetic field created with axisymmetric coils in arbitrary points of space, including points located inside a coil or on its border, is obtained. The basic idea of the method is to replace a current coil with continuous distribution of current density by magnetization distributed in the volume of the coil and creating the equivalent magnetic field. This allows to use field surface sources at calculation of the fields. Consequently, the range of integration is reduced resulting in reduction of calculation volume by an order in most cases. Besides, the calculation of improper integrals in internal points and on the border is completely excluded.

  15. Calculation of an axisymmetric current coil field with the bounding contour integration method

    International Nuclear Information System (INIS)

    Telegin, Alexander P.; Klevets, Nickolay I.

    2004-01-01

    Method for the economic and stable (in the sense of calculation errors) analysis of an induction of a magnetic field created with axisymmetric coils in arbitrary points of space, including points located inside a coil or on its border, is obtained. The basic idea of the method is to replace a current coil with continuous distribution of current density by magnetization distributed in the volume of the coil and creating the equivalent magnetic field. This allows to use field surface sources at calculation of the fields. Consequently, the range of integration is reduced resulting in reduction of calculation volume by an order in most cases. Besides, the calculation of improper integrals in internal points and on the border is completely excluded

  16. Enhanced MR angiography of the lower extremities with synergy spine coil

    International Nuclear Information System (INIS)

    Takashima, Hiroyuki; Watanabe, Naoki

    2002-01-01

    A synergy spine coil is a phased-array coil designed for spine imaging. The coil's sensitive area is narrow in both the x-axis and y-axis directions but very wide in the z-axis direction. It is therefore suitable for using in long parts of the body, such as the spine. We used the coil for enhanced MR angiography in the lower extremities, which requires a very long field of view on the z-axis direction. Using on the NEMA (National Electrical Manufacturers Association) standard test for special-purpose coils, the sensitive volume of the synergy spine coil was first measured by using a phantom. It was found that the sensitive lengths along x-axis and y-axis were 300 mm and 120 mm, respectively, while that along z-axis could set at any length required for the examination by modifying the element number. The above area was confirmed to be sufficient for obtaining enhanced MR angiograms of the lower extremities. The results of this study showed the use of the synergy spine coil in enhanced MR angiography of the lower extremities is superior to the use of a conventional whole body coil for obtaining good MR angiograms with a good single-to-noise ratio (SNR). (author)

  17. SU-E-J-88: Margin Reduction of Level II/III Planning Target Volume for Image-Guided Simultaneous Integrated Boost Head-And-Neck Treatment

    International Nuclear Information System (INIS)

    Can, S; Neylon, J; Qi, S; Santhanam, A; Low, D

    2014-01-01

    Purpose: To investigate the feasibility of improved normal tissue sparing for head-and-neck (H'N) image-guided radiotherapy (IGRT) by employing tighter CTV-to-PTV margins for target level II/III though a GPU-based deformable image registration and dose accumulation framework. Methods: Ten H'N simultaneous integrated boost cases treated on TomoTherapy were retrospectively analyzed. Weekly kVCT scans in addition to daily MVCT scans were acquired for each patient. Reduced margin plans were generated with 0- mm margin for level II and III PTV (while 3-5 mm margin for PTV1) and compared with the standard margin plan using 3-5mm margin to all CTV1-3 (reference plan). An in-house developed GPU-based 3D image deformation tool was used to register and deform the weekly KVCTs with the planning CT and determine the delivered mean/minimum/maximum dose, dose volume histograms (DVHs), etc. Results: Compared with the reference plans, the averaged cord maximum, the right and left parotid doses reduced by 22.7 %, 16.5 %, and 9 % respectively in the reduced margin plans. The V95 for PTV2 and PTV3 were found within 2 and 5% between the reference and tighter margin plans. For the reduced margin plans, the averaged cumulative mean doses were consistent with the planned dose for PTV1, PTV2 and PTV3 within 1.5%, 1.7% and 1.4%. Similar dose variations of the delivered dose were seen for the reference and tighter margin plans. The delivered maximum and mean doses for the cord were 3.55 % and 2.37% higher than the planned doses; a 5 % higher cumulative mean dose for the parotids was also observed for the delivered dose than the planned doses in both plans. Conclusion: By imposing tighter CTV-to-PTV margins for level II and III targets for H'N irradiation, acceptable cumulative doses were achievable when coupled with weekly kVCT guidance while improving normal structure sparing

  18. Effect of γ-Al2O3/water nanofluid on the thermal performance of shell and coil heat exchanger with different coil torsions

    Science.gov (United States)

    Elshazly, K. M.; Sakr, R. Y.; Ali, R. K.; Salem, M. R.

    2017-06-01

    This work investigated experimentally the thermal performance of shell and coil heat exchanger with different coil torsions (λ) for γ-Al2O3/water nanofluid flow. Five helically coiled tube (HCT) with 0.0442 ≤ λ ≤ 0.1348 were tested within turbulent flow regime. The average size of γ-Al2O3 particles is 40 nm and volume concentration (φ) is varied from 0 to 2%. Results showed that reducing coil torsion enhances the heat transfer rate and increases HCT-friction factor (fc). Also, it is noticed that HCT average Nusselt number (Nut) and fc of nanofluids increase with increasing γ-Al2O3 volume concentration. The thermal performance index, TPI = (ht,nf/ht,bf)/(ΔPc,nf/ΔPc,bf). increases with increasing nanoparticles concentration, coil torsion, HCT-side inlet temperature and nanofluid flow rate. Over the studied range of HCT-Reynolds number, the average value of TPI is of 1.34 and 2.24 at φ = 0.5% and φ = 2%, respectively. The average value of TPI is of 1.64 at λ = 0.0442 while its average value at λ = 0.1348 is of 2.01. One of the main contributions is to provide heat equipments designers with Nut and fc correlations for practical configurations shell and coil heat exchangers with a wide range of nanofluid concentration.

  19. Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case–control study in long-term survivors from cancer in the head and neck region

    International Nuclear Information System (INIS)

    Olsson, Erik; Löfdahl, Elisabet; Malmgren, Helge; Eckerström, Carl; Berg, Gertrud; Borga, Magnus; Ekholm, Sven; Johannsson, Gudmundur; Ribbelin, Susanne; Starck, Göran; Wysocka, Anna

    2012-01-01

    An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients’ lowered QoL was coupled to a reduction in hippocampal volume. Patients (11 men and 4 women, age 31–65) treated for head and neck cancer 4–10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 – 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon’s signed rank test were used for the main statistical analysis. There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients. The study gives solid evidence against the hypothesis that the patients’ lowered quality of life was due to a major reduction of hippocampal volume

  20. Coil Migration through a Neuroform 3 Stent during Endovascular Coiling. A Case Report.

    LENUS (Irish Health Repository)

    O'Hare, A

    2009-07-29

    Summary: A 43-year-old woman attended for stent assisted coiling. A Neuroform 30 x 4.5 mm stent had been successfully placed over the left periophthalmic aneurysm. During the coiling the first coil migrated through the crowns in the stent, lodging at the MCA bifurcation. We believe that the coil herniated through the overlying stent due to the carotid siphon curvature and the open cell design. Furthermore the distal markers of the stent impeded coil extraction with a MERCI device.

  1. Examination of measurement and its method of compensation of the sensitivity distribution using phased array coil for body scan

    CERN Document Server

    Kimura, T; Iizuka, A; Taniguchi, Y; Ishikuro, A; Hongo, T; Inoue, H; Ogura, A

    2003-01-01

    The influence on the quality of images by measurement of a sensitivity distribution and the use of a sensitivity compensation filter was considered using an opposite-type phased array coil and volume-type phased array coil. With the opposite-type phased array coil, the relation between coil interval and filter was investigated for the image intensity correction (IIC) filter, surface coil intensity correction (SCIC) filter (GE), and the Normalize filter (SIEMENS). The SCIC filter and Normalize filter showed distance dependability over the coil interval of signal-to-noise ratio (SNR) and uniformity was observed, and the existence of an optimal coil interval was suggested. Moreover, with the IIC filter, distance dependability over a coil interval was small, and the decrease in contrast with use was remarkable. On the other hand, with the volume-type phased array coil, the overlap of an array element was investigated to determine the influence it had on sensitivity distribution. Although the value stabilized in t...

  2. An inflatable surface coil for rectal imaging

    International Nuclear Information System (INIS)

    Martin, J.F.; Hajek, P.C.; Baker, L.L.; Gylys-Morin, V.; Mattrey, R.F.

    1986-01-01

    Surface coils have become ubiquitous in MR imaging of the body because of substantial gains in signal-to-noise ratio. Unfortunately, there are some anatomic regions, such as the prostate, for which surface coils have insufficient depth sensitivity. The authors have developed an inflatable, distributed capacitance, passively decoupled surface coil which is collapsed for insertion and reinflated for imaging. Images of the prostate are dramatically improved due to proximity of the coil. Lesions in cadaver specimens were observed which were not seen with body coil imaging. Clinical trials are expected to begin in September

  3. Design optimization of superconducting magnetic energy storage coil

    Energy Technology Data Exchange (ETDEWEB)

    Bhunia, Uttam, E-mail: ubhunia@vecc.gov.in; Saha, Subimal; Chakrabarti, Alok

    2014-05-15

    Highlights: • We modeled the optimization formulation that minimizes overall refrigeration load into the SMES cryostat. • Higher the operating current reduces the dynamic load but increases static heat load into the cryostat. • Higher allowable hoop stress reduces both coil volume and refrigeration load. • The formulation can be in general be utilized for any arbitrary specification of SMES coil and conductor type. - Abstract: An optimization formulation has been developed for a superconducting magnetic energy storage (SMES) solenoid-type coil with niobium titanium (Nb–Ti) based Rutherford-type cable that minimizes the cryogenic refrigeration load into the cryostat. Minimization of refrigeration load reduces the operating cost and opens up the possibility to adopt helium re-condensing system using cryo-cooler especially for small-scale SMES system. Dynamic refrigeration load during charging or discharging operational mode of the coil dominates over steady state load. The paper outlines design optimization with practical design constraints like actual critical characteristics of the superconducting cable, maximum allowable hoop stress on winding, etc., with the objective to minimize refrigeration load into the SMES cryostat. Effect of design parameters on refrigeration load is also investigated.

  4. ANL experimental program for pulsed superconducting coils

    International Nuclear Information System (INIS)

    Wang, S.T.; Kim, S.H.; Praeg, W.F.; Krieger, C.I.

    1978-01-01

    Argonne National Laboratory (ANL) had recognized the clear advantage of a superconducting ohmic-heating (OH) coil and started in aggressive development program in FY 1977. The main objectives for FY 1977 are to develop cryostable basic cable configurations with reasonably low ac losses, to develop 12 kA cryostable cable, using it to design and build a 1.5 MJ pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat for the 1.5 MJ pulsed coil. The principal objective in building the 1.5 MJ ac coil is to demonstrate ac cryostability of a large coil ranging from 2 T/s up to 12 T/s. Another objective in the pulsed coil program is to determine the feasibility of parallel coil operation in order to avoid excessive voltage and current requirements and to minimize the number of turns for the equilibrium field (EF) coils, should the EF coils be connected in parallel with the OH coils. A two-coil section model using the 11 kA cable will be built and tested

  5. Pulse coil concepts for the LCP Facility

    International Nuclear Information System (INIS)

    Nelson, B.E.; Burn, P.B.

    1977-01-01

    The pulse coils described in this paper are resistive copper magnets driven by time-varying currents. They are included in the Large Coil Test Facility (LCTF) portion of the Large Coil Program (LCP) to simulate the pulsed field environment of the toroidal coils in a tokamak reactor. Since TNS (a 150 sec, 5MA, igniting tokamak) and the Oak Ridge EPR (Experimental Power Reactor) are representative of the first tokamaks to require the technology developed in LCP, the reference designs for these machines, especially TNS, are used to derive the magnetic criteria for the pulse coils. This criteria includes the magnitude, distribution, and rate of change of pulsed fields in the toroidal coil windings. Three pulse coil concepts are evaluated on the basis of magnetic criteria and factors such as versatility of design, ease of fabrication and cost of operation. The three concepts include (1) a pair of poloidal coils outside the LCTF torus, (2) a single poloidal coil threaded through the torus, and (3) a pair of vertical axis coil windings inside the bore of one or more of the toroidal test coils

  6. ANL experimental program for pulsed superconducting coils

    International Nuclear Information System (INIS)

    Wang, S.T.; Kim, S.H.; Praeg, W.F.; Krieger, C.I.

    1977-01-01

    Argonne National Laboratory (ANL) had recognized the clear advantage of a superconducting ohmic-heating (OH) coil and started an aggressive development program in FY 1977. The main objectives for FY 1977 are to develop cryostable basic cable configurations with reasonably low ac losses, to develop 12 kA cryostable cable, using it to design and build a 1.5 MJ pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat for the 1.5 MJ pulsed coil. The principal objective in building the 1.5 MJ ac coil is to demonstrate ac cryostability of a large coil ranging from 2 T/s up to 12 T/s. Another objective in the pusled coil program is to determine the feasibility of parallel coil operation in order to avoid excessive voltage and current requirements and to minimize the number of turns for the equilibrium field (EF) coils, should the EF coils be connected in parallel with the OH coils. A two-coil section model using the 11 kA cable will be built and tested

  7. Performance evaluation of matrix gradient coils.

    Science.gov (United States)

    Jia, Feng; Schultz, Gerrit; Testud, Frederik; Welz, Anna Masako; Weber, Hans; Littin, Sebastian; Yu, Huijun; Hennig, Jürgen; Zaitsev, Maxim

    2016-02-01

    In this paper, we present a new performance measure of a matrix coil (also known as multi-coil) from the perspective of efficient, local, non-linear encoding without explicitly considering target encoding fields. An optimization problem based on a joint optimization for the non-linear encoding fields is formulated. Based on the derived objective function, a figure of merit of a matrix coil is defined, which is a generalization of a previously known resistive figure of merit for traditional gradient coils. A cylindrical matrix coil design with a high number of elements is used to illustrate the proposed performance measure. The results are analyzed to reveal novel features of matrix coil designs, which allowed us to optimize coil parameters, such as number of coil elements. A comparison to a scaled, existing multi-coil is also provided to demonstrate the use of the proposed performance parameter. The assessment of a matrix gradient coil profits from using a single performance parameter that takes the local encoding performance of the coil into account in relation to the dissipated power.

  8. Coiled tubing drilling with supercritical carbon dioxide

    Science.gov (United States)

    Kolle , Jack J.

    2002-01-01

    A method for increasing the efficiency of drilling operations by using a drilling fluid material that exists as supercritical fluid or a dense gas at temperature and pressure conditions existing at a drill site. The material can be used to reduce mechanical drilling forces, to remove cuttings, or to jet erode a substrate. In one embodiment, carbon dioxide (CO.sub.2) is used as the material for drilling within wells in the earth, where the normal temperature and pressure conditions cause CO.sub.2 to exist as a supercritical fluid. Supercritical carbon dioxide (SC--CO.sub.2) is preferably used with coiled tube (CT) drilling equipment. The very low viscosity SC--CO.sub.2 provides efficient cooling of the drill head, and efficient cuttings removal. Further, the diffusivity of SC--CO.sub.2 within the pores of petroleum formations is significantly higher than that of water, making jet erosion using SC--CO.sub.2 much more effective than water jet erosion. SC--CO.sub.2 jets can be used to assist mechanical drilling, for erosion drilling, or for scale removal. A choke manifold at the well head or mud cap drilling equipment can be used to control the pressure within the borehole, to ensure that the temperature and pressure conditions necessary for CO.sub.2 to exist as either a supercritical fluid or a dense gas occur at the drill site. Spent CO.sub.2 can be vented to the atmosphere, collected for reuse, or directed into the formation to aid in the recovery of petroleum.

  9. Analysing radio-frequency coil arrays in high-field magnetic resonance imaging by the combined field integral equation method

    Energy Technology Data Exchange (ETDEWEB)

    Wang Shumin; Duyn, Jeff H [Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, 10/B1D728, Bethesda, MD 20892 (United States)

    2006-06-21

    We present the combined field integral equation (CFIE) method for analysing radio-frequency coil arrays in high-field magnetic resonance imaging (MRI). Three-dimensional models of coils and the human body were used to take into account the electromagnetic coupling. In the method of moments formulation, we applied triangular patches and the Rao-Wilton-Glisson basis functions to model arbitrarily shaped geometries. We first examined a rectangular loop coil to verify the CFIE method and also demonstrate its efficiency and accuracy. We then studied several eight-channel receive-only head coil arrays for 7.0 T SENSE functional MRI. Numerical results show that the signal dropout and the average SNR are two major concerns in SENSE coil array design. A good design should be a balance of these two factors.

  10. Design and use of a folded four-ring double-tuned birdcage coil for rat brain sodium imaging at 9.4 T.

    Science.gov (United States)

    Ha, YongHyun; Choi, Chang-Hoon; Worthoff, Wieland A; Shymanskaya, Aliaksandra; Schöneck, Michael; Willuweit, Antje; Felder, Jörg; Shah, N Jon

    2018-01-01

    A folded four-ring quadrature birdcage coil was designed and constructed with a double-tune configuration of an outer high-pass coil for 1 H (400 MHz) and inner low-pass coil for 23 Na (105.72 MHz at 9.4 T). The coil was evaluated on the bench and in the scanner, comparing its performance with that of single-tuned coils and a large four-ring coil. All coils were tuned and matched and the isolation between two quadrature ports was found to be better than -13.7 dB for 1 H and -27 dB for 23 Na. Signal-to-noise ratios (SNRs) were calculated and 23 Na flip angle maps were acquired. 23 Na SNR of the folded four-ring reached ∼93% of that obtained with the single-tuned coil. A set of in vivo 1 H and 23 Na axial images to cover the whole rat brain were obtained. The performance of the folded four-ring coil and its benefit for 23 Na imaging experiments have been demonstrated. This proposed four-ring coil could avoid length restrictions, e.g. the shoulders, by folding the outer rings vertically. This facilitates the construction of double-tuned four-ring birdcage coils just to fit the head, leading to higher filling factors and better SNR. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Design and use of a folded four-ring double-tuned birdcage coil for rat brain sodium imaging at 9.4 T

    Science.gov (United States)

    Ha, YongHyun; Choi, Chang-Hoon; Worthoff, Wieland A.; Shymanskaya, Aliaksandra; Schöneck, Michael; Willuweit, Antje; Felder, Jörg; Shah, N. Jon

    2018-01-01

    A folded four-ring quadrature birdcage coil was designed and constructed with a double-tune configuration of an outer high-pass coil for 1H (400 MHz) and inner low-pass coil for 23Na (105.72 MHz at 9.4 T). The coil was evaluated on the bench and in the scanner, comparing its performance with that of single-tuned coils and a large four-ring coil. All coils were tuned and matched and the isolation between two quadrature ports was found to be better than -13.7 dB for 1H and -27 dB for 23Na. Signal-to-noise ratios (SNRs) were calculated and 23Na flip angle maps were acquired. 23Na SNR of the folded four-ring reached ∼93% of that obtained with the single-tuned coil. A set of in vivo1H and 23Na axial images to cover the whole rat brain were obtained. The performance of the folded four-ring coil and its benefit for 23Na imaging experiments have been demonstrated. This proposed four-ring coil could avoid length restrictions, e.g. the shoulders, by folding the outer rings vertically. This facilitates the construction of double-tuned four-ring birdcage coils just to fit the head, leading to higher filling factors and better SNR.

  12. Judgement of the effectivity of radiotherapy on the basis of volume change by lymph node metastasis of head and neck tumors; Volumenveraenderung der Halslymphknotenmetastasen bei Kopf-Hals-Tumoren

    Energy Technology Data Exchange (ETDEWEB)

    Liszka, G. [Staatliches Onkologisches Inst., Budapest (Hungary). Roentgendiagnostische Abt.; Thalacker, U. [Staatliches Onkologisches Inst., Budapest (Hungary). Roentgendiagnostische Abt.; Somogyi, A. [Imre-Haynal-Universitaet fuer Gesundheitswissenschaften, Budapest (Hungary). Strahlentherapeutischer Lehrstuhl; Nemeth, G. [Imre-Haynal-Universitaet fuer Gesundheitswissenschaften, Budapest (Hungary). Strahlentherapeutischer Lehrstuhl

    1997-08-01

    Aim: This work is engaged with the volume change of neck lymph node metastasis of malignant tumors in the head-neck region during radiotherapy. Patients and Method: In 54 patients with head and neck tumors, the volume of neck lymph nodes before and after radiation was measured. The volumetry was done with CT planimetry. The total dose was 66 Gy (2 Gy/d) telecobalt from 2 lateral opponated fields. The time of volume change could be defined with measuring of the half-time and the doubling-time by the help of Schwartz formula. Results: After 10 Gy the volume diminution was about 20% and half-time 24 to 26 days. Afterwards the time of volume diminution picked up speed and finally achieved 60 to 72%. Meanwhile the half-time decreased to the half value. The result was independent of the site of primary tumor, the patient`s sex and age. (orig.) [Deutsch] Ziel: Diese Arbeit beschaeftigt sich mit der Volumenveraenderung von Halslymphknotenmetastasen maligner Tumoren im Kopf-Hals-Bereich waehrend einer strahlentherapeutischen Behandlung. Patienten und Methode: Bei 54 Patienten mit Kopf-Hals-Tumoren wurde das Volumen der Halslymphknotenmetastasen vor und nach Strahlenbehandlung (bei sieben Patienten auch nach 10 Gy) bestimmt. Der Primaertumor war in allen Faellen ein Plattenepithelkarzinom. Zur Bestimmung des Volumens der Lymphknotenmetastasen bietet sich als genauestes bildgebendes Verfahren die CT-Planimetrie an. Jeder Patient wurde mit Telekobalt ueber zwei opponierende laterale Felder bis zu einer Gesamtdosis von 66 Gy (taegliche Einzeldosis 2 Gy) bestrahlt. Die Dynamik der durch die Bestrahlung hervorgerufenen Volumenveraenderung wurde mit Hilfe der Halbwerts- bzw. Verdoppelungszeit nach der Formel von Schwartz berechnet. Ergebnisse: Nach 10 Gy betrug die Volumenverkleinerung etwa 20%, die Halbwertszeit 24 bis 26 Tage. Danach beschleunigte sich die Volumenverkleinerung und erreichte zuletzt 60 bis 72%. Die Halbwertszeit verringerte sich auf etwa die Haelfte. Das Ausmass

  13. Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing.

    Science.gov (United States)

    Snoberger, Aaron; Brettrager, Evan J; Smith, David M

    2018-06-18

    Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conformations: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN's symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases' coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils regulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity.

  14. Comparison of target volumes in radiotherapy defined on scanner and on PET-T.D.M. with {sup 18}F-F.D.G. in the frame of head and neck cancers; Comparaison des volumes cibles en radiotherapie definis sur scanner et sur TEP-TDM au 18F FDG dans le cadre des cancers de la tete et du cou

    Energy Technology Data Exchange (ETDEWEB)

    Henriques De Figueiredo, B.; Barret, O.; Allard, M.; Fernandez, P. [Service de medecine nucleaire, CHU de Pellegrin, Bordeaux, (France); Demeaux, H.; Maire, J.P.; Lagarde, P. [service de radiotherapie, hopital Saint-Andre, Bordeaux, (France); Kantor, G.; Richau, P. [departement de radiotherapie, institut Bergonie, Bordeaux, (France); De Mones Del Pujol, E. [service d' ORL, hopital Pellegrin, Bordeaux, (France)

    2009-05-15

    The objective is to study in a prospective way, in the frame of head and neck cancers, the impact of the positron computed tomography with {sup 18}F fluorodeoxyglucose (PET-F.D.G.) on the limitation of target volumes in radiotherapy. In conclusions, the gross tumor volume (G.T.V.) defined on PET is smaller than this one defined on scanner, that could be interesting in radiotherapy, in the perspective of a dose escalation. In addition, areas of discordance exist between the clinical target volumes (C.T.V.70 and C.T.V.50) defined on PET and on scanner. These discordances, synonyms of under or over estimation of target volumes, could have important clinical consequences in term of local control and toxicity. (N.C.)

  15. Characterization of the first RF coil dedicated to 1.5 T MR guided radiotherapy

    Science.gov (United States)

    Hoogcarspel, Stan J.; Zijlema, Stefan E.; Tijssen, Rob H. N.; Kerkmeijer, Linda G. W.; Jürgenliemk-Schulz, Ina M.; Lagendijk, Jan J. W.; Raaymakers, Bas W.

    2018-01-01

    The purpose of this study is to investigate the attenuation characteristics of a novel radiofrequency (RF) coil, which is the first coil that is solely dedicated to MR guided radiotherapy with a 1.5 T MR-linac. Additionally, we investigated the impact of the treatment beam on the MRI performance of this RF coil. First, the attenuation characteristics of the RF coil were characterized. Second, we investigated the impact of the treatment beam on the MRI performance of the RF coil. We additionally demonstrated the ability of the anterior coil to attenuate returning electrons and thereby reducing the dose to the skin at the distal side of the treatment beam. Intensity modulated radiation therapy simulation of a clinically viable treatment plan for spinal bone metastasis shows a decrease of the dose to the planned tumor volume of 1.8% as a result of the MR coil around the patient. Ionization chamber and film measurements show that the anterior and posterior coil attenuate the beam homogeneously by 0.4% and 2.2%, respectively. The impact of the radiation resulted in a slight drop of the time-course signal-to-noise ratio and was dependent on imaging parameters. However, we could not observe any image artifacts resulting from this irradiation in any situation. In conclusion, the investigated MR-coil can be utilized for treatments with the 1.5 T-linac system. However, there is still room for improvement when considering both the dosimetric and imaging performance of the coil.

  16. Remote maintenance of tandem mirror hybrid coils

    International Nuclear Information System (INIS)

    Dietz, L.P.

    1983-01-01

    Hybrid Coils (superconducting coils with normal conducting inserts) are being employed with increasing frequency on Tandem Mirror Devices to obtain high field strengths. The normal conducting copper inserts are short lived in comparison to their encircling superconductors. It becomes desirable, therefore, to devise design features and maintenance procedures to replace the inner normal conducting coils without simultaneously replacing the longer lived (and significantly more costly) superconducting coils. The high neutron wall loadings require that the task be accomplished by remote control. The approach is to permanently mount the coil assemblies on track mounted carriages which serve, during machine operation merely as structural supports, but during maintenance procedures as moveable transport devices. The carriages incorporate all necessary provisions to facilitate remote maintenance operations and to adjust and align the coil assemblies with respect to adjacent machine components. The vacuum vessel is severed on both sides of the hybrid coil by means of a remote cutting machine. The entire coil is transported horizontally, normal to the machine axis to a nearby repair station. Prepositioned carriage mounted repair equipment at the repair station withdraws the damaged normal coil as a single entity and inserts a preassembled spare unit. The repaired hybrid coil is reassembled to the reactor. A cost and risk effective procedure has been evolved to maintain one of the more critical components of a Tandem Mirror Machine

  17. Discussion of discrete D shape toroidal coil

    International Nuclear Information System (INIS)

    Kaiho, Katsuyuki; Ohara, Takeshi; Agatsuma, Ko; Onishi, Toshitada

    1988-01-01

    A novel design for a toroidal coil, called the D shape coil, was reported by J. File. The coil conductors are in pure tension and then subject to no bending moment. This leads to a smaller number of emf supports in a simpler configuration than that with the conventional toroidal coil of circular cross-section. The contours of the D shape are given as solutions of a differential equation. This equation includes the function of the magnetic field distribution in the conductor region which is inversely proportional to the winding radius. It is therefore important to use the exact magnetic field distribution. However the magnetic field distribution becomes complicated when the D shape toroidal coil is comprised of discrete coils and also depends on the D shape configuration. A theory and a computer program for designing the practical pure-tension toroidal coil are developed. Using this computer code, D shape conductors are calculated for various numbers of discrete coils and the results are compared. Electromagnetic forces in the coils are also calculated. It is shown that the hoop stress in the conductors depends only on the total ampere-turns of the coil when the contours of the D shape are similar. (author)

  18. Large coil test facility conceptual design report

    International Nuclear Information System (INIS)

    Nelms, L.W.; Thompson, P.B.; Mann, T.L.

    1978-02-01

    In the development of a superconducting toroidal field (TF) magnet for The Next Step (TNS) tokamak reactor, several different TF coils, about half TNS size, will be built and tested to permit selection of a design and fabrication procedure for full-scale TNS coils. A conceptual design has been completed for a facility to test D-shaped TF coils, 2.5 x 3.5-m bore, operating at 4-6 K, cooled either by boiling helium or by forced-flow supercritical helium. Up to six coils can be accommodated in a toroidal array housed in a single vacuum tank. The principal components and systems in the facility are an 11-m vacuum tank, a test stand providing structural support and service connections for the coils, a liquid nitrogen system, a system providing helium both as saturated liquid and at supercritical pressure, coils to produce a pulsed vertical field at any selected test coil position, coil power supplies, process instrumentation and control, coil diagnostics, and a data acquisition and handling system. The test stand structure is composed of a central bucking post, a base structure, and two horizontal torque rings. The coils are bolted to the bucking post, which transmits all gravity loads to the base structure. The torque ring structure, consisting of beams between adjacent coils, acts with the bucking structure to react all the magnetic loads that occur when the coils are energized. Liquid helium is used to cool the test stand structure to 5 K to minimize heat conduction to the coils. Liquid nitrogen is used to precool gaseous helium during system cooldown and to provide thermal radiation shielding

  19. Assessment of a PML Boundary Condition for Simulating an MRI Radio Frequency Coil

    Directory of Open Access Journals (Sweden)

    Yunsuo Duan

    2008-01-01

    Full Text Available Computational methods such as the finite difference time domain (FDTD play an important role in simulating radiofrequency (RF coils used in magnetic resonance imaging (MRI. The choice of absorbing boundary conditions affects the final outcome of such studies. We have used FDTD to assess the Berenger's perfectly matched layer (PML as an absorbing boundary condition for computation of the resonance patterns and electromagnetic fields of RF coils. We first experimentally constructed a high-pass birdcage head coil, measured its resonance pattern, and used it to acquire proton (1H phantom MRI images. We then computed the resonance pattern and B1 field of the coil using FDTD with a PML as an absorbing boundary condition. We assessed the accuracy and efficiency of PML by adjusting the parameters of the PML and comparing the calculated results with measured ones. The optimal PML parameters that produce accurate (comparable to the experimental findings FDTD calculations are then provided for the birdcage head coil operating at 127.72 MHz, the Larmor frequency of 1H at 3 Tesla (T.

  20. Development of a new error field correction coil (C-coil) for DIII-D

    International Nuclear Information System (INIS)

    Robinson, J.I.; Scoville, J.T.

    1995-12-01

    The C-coil recently installed on the DIII-D tokamak was developed to reduce the error fields created by imperfections in the location and geometry of the existing coils used to confine, heat, and shape the plasma. First results from C-coil experiments include stable operation in a 1.6 MA plasma with a density less than 1.0 x 10 13 cm -3 , nearly a factor of three lower density than that achievable without the C-coil. The C-coil has also been used in magnetic braking of the plasma rotation and high energy particle confinement experiments. The C-coil system consists of six individual saddle coils, each 60 degree wide toroidally, spanning the midplane of the vessel with a vertical height of 1.6 m. The coils are located at a major radius of 3.2 m, just outside of the toroidal field coils. The actual shape and geometry of each coil section varied somewhat from the nominal dimensions due to the large number of obstructions to the desired coil path around the already crowded tokamak. Each coil section consists of four turns of 750 MCM insulated copper cable banded with stainless steel straps within the web of a 3 in. x 3 in. stainless steel angle frame. The C-coil structure was designed to resist peak transient radial forces (up to 1,800 Nm) exerted on the coil by the toroidal and ploidal fields. The coil frames were supported from existing poloidal field coil case brackets, coil studs, and various other structures on the tokamak

  1. Proceedings of the twenty-fourth water reactor safety information meeting. Volume 2: Reactor pressure vessel embrittlement and thermal annealing; Reactor vessel lower head integrity; Evaluation and projection of steam generator tube condition and integrity

    Energy Technology Data Exchange (ETDEWEB)

    Monteleone, S. [comp.] [Brookhaven National Lab., Upton, NY (United States)

    1997-02-01

    This three-volume report contains papers presented at the Twenty-Fourth Water Reactor Safety Information Meeting held at the Bethesda Marriott Hotel, Bethesda, Maryland, October 21--23, 1996. The papers are printed in the order of their presentation in each session and describe progress and results of programs in nuclear safety research conducted in this country and abroad. Foreign participation in the meeting included papers presented by researchers from Czech Republic, Finland, France, Japan, Norway, Russia and United Kingdom. This volume is divided into the following sections: reactor pressure vessel embrittlement and thermal annealing; reactor vessel lower head integrity; and evaluation and projection of steam generator tube condition and integrity. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  2. Proceedings of the twenty-fourth water reactor safety information meeting. Volume 2: Reactor pressure vessel embrittlement and thermal annealing; Reactor vessel lower head integrity; Evaluation and projection of steam generator tube condition and integrity

    International Nuclear Information System (INIS)

    Monteleone, S.

    1997-02-01

    This three-volume report contains papers presented at the Twenty-Fourth Water Reactor Safety Information Meeting held at the Bethesda Marriott Hotel, Bethesda, Maryland, October 21--23, 1996. The papers are printed in the order of their presentation in each session and describe progress and results of programs in nuclear safety research conducted in this country and abroad. Foreign participation in the meeting included papers presented by researchers from Czech Republic, Finland, France, Japan, Norway, Russia and United Kingdom. This volume is divided into the following sections: reactor pressure vessel embrittlement and thermal annealing; reactor vessel lower head integrity; and evaluation and projection of steam generator tube condition and integrity. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database

  3. Argonne National Laboratory superconducting pulsed coil program

    International Nuclear Information System (INIS)

    Wang, S.T.; Kim, S.H.

    1979-01-01

    The main objectives are to develop high current (approx. 100 kA) cryostable cable configurations with reasonably low ac losses, to build a demonstration pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat. A 1.5-MJ cryostable pulsed superconducting coil has been developed and constructed at ANL. The coil has a peak field of 4.5 T at an operating current of 11.0 kA. A large inexpensive plastic cryostat has been developed for testing the pulsed coil. The coil has been pulsed with a maximum dB/dt of 11 T/s. The coil was pulsed more than 4000 cycles. Detailed results of the ac loss measurements and the current sharing of the cryostability will be described

  4. Test facility for PLT TF coils

    International Nuclear Information System (INIS)

    Hearney, J.; File, J.; Dreskin, S.

    1975-01-01

    Past experience with the model C stellerator and other toroidal field devices indicates that mechanical and electrical tests of a toroidal field coil prior to maximum field operation of the device is prudent and desirable. This paper describes a test program for the PLT-TF coils. The test stand consists of one test coil, two background coils and a steel supporting structure. The three coil configuration produces a 67.5 kG field at the inner conductor (38 kG at the bore center) and simulates a 1/R field distribution in the bore of the test coil. The resolution of the field force system and resultant stresses within the test structure are discussed. A test procedure is described which maximizes the information obtained from a 100,000 pulse program

  5. Power loss problems in EXTRAP coil systems

    International Nuclear Information System (INIS)

    Lehnert, B.

    1977-02-01

    The Ohmic power loss in the coils of external ring traps is minimized with respect to the thermonuclear power production. In the case of the DT-reaction this leads to dimensions and power densities being relevant to full-scale reactors. Not only superconducting or refrigerated coil windings can thus be used, but also hot-coil systems which are operated at several hundred degrees centrigrade and form part of a steam cycle and power extraction system. For hot coils the problems of void formation and tritium regeneration have to be further examined. The high beta value leads to moderately large coil stresses. Finally, replacement and repair become simplified by the present coil geometry. (Auth.)

  6. Coil supporting device for thermonuclear device

    International Nuclear Information System (INIS)

    Okubo, Minoru; Ando, Toshiro; Ota, Mitsuru; Ishimura, Masabumi.

    1979-01-01

    Purpose: To lower the bending stress exerted on coils thereby preventing the coils from deformation by branching the outer circumferential support frames of coil support frames disposed at an equal pitch circumferentially to the coils into plurality, and integrally forming them to the inner circumferential support frames. Constitution: Each of the support frames for supporting poloidal coils winding around a vacuum vessel is bisected at the radial midway so that the outer circumferential branches are disposed at an equal pitch and they are formed integrally with the inner circumferential support frames. The inner circumferential support frames are fixed by support posts on a bed and the outer circumferential support frames are mounted to the outer edge of wedge-like support posts. Accordingly, if the coils expand outwardly upon increase in the temperature, the stress exerted on the support frame can be decreased. (Yoshino, Y.)

  7. Split-coil-system SULTAN

    International Nuclear Information System (INIS)

    Vecsey, G.

    1992-08-01

    The high field superconductor test facility SULTAN started operation successfully in May 1992. Originally designed for testing full scale conductors for the large magnets of the next generation fusion reactors, the SULTAN facility installed at PSI (Switzerland) was designed as a common venture of three European Laboratories: ENEA (Italy), ECN (Netherlands) and PSI, and built by ENEA and PSI in the framework of the Euratom Fusion Technology Program. Presently the largest facility in the world, with its superconducting split coil system generating 11 Tesla in a 0.6 m bore, it is ready now for testing superconductor samples with currents up to 50 kA at variable cooling conditions. Similar tests can be arranged also for other applications. SULTAN is offered by the European Community as a contribution to the worldwide cooperation for the next step of fusion reactor development ITER. First measurements on conductor developed by CEA (Cadarache) are now in progress. Others like those of ENEA and CERN will follow. For 1993, a test of an Italian 12 TZ model coil for fusion application is planned. SULTAN is a worldwide unique facility marking the competitive presence of Swiss technology in the field of applied superconductivity research. Based on development and design of PSI, the high field Nb 3 Sn superconductors and coils were fabricated at the works of Kabelwerke Brugg and ABB, numerous Swiss companies contributed to the success of this international effort. Financing of the Swiss contribution of SULTAN was made available by NEFF, BEW, BBW, PSI and EURATOM. (author) figs., tabs., 20 refs

  8. DEVELOPMENT OF COILED TUBING STRESS ANALYSIS

    Directory of Open Access Journals (Sweden)

    Davorin Matanović

    1998-12-01

    Full Text Available The use of coiled tubing is increasing rapidly with drilling of horizontal wells. To satisfy all requirements (larger mechanical stresses, larger fluid capacities the production of larger sizes and better material qualities was developed. Stresses due to axial forces and pressures that coiled tubing is subjected are close to its performance limits. So it is really important to know and understand the behaviour of coiled tubing to avoid its break, burst or collapse in the well.

  9. A 16-channel receive, forced current excitation dual-transmit coil for breast imaging at 7T.

    Directory of Open Access Journals (Sweden)

    Samantha By

    Full Text Available To enable high spatial and temporal breast imaging resolution via combined use of high field MRI, array coils, and forced current excitation (FCE multi channel transmit.A unilateral 16-channel receive array insert was designed for use in a transmit volume coil optimized for quadrature operation with dual-transmit RF shimming at 7 T. Signal-to-noise ratio (SNR maps, g-factor maps, and high spatial and temporal resolution in vivo images were acquired to demonstrate the utility of the coil architecture.The dual-transmit FCE coil provided homogeneous excitation and the array provided an increase in average SNR of 3.3 times (max 10.8, min 1.5 compared to the volume coil in transmit/receive mode. High resolution accelerated in vivo breast imaging demonstrated the ability to achieve isotropic spatial resolution of 0.5 mm within clinically relevant 90 s scan times, as well as the ability to perform 1.0 mm isotropic resolution imaging, 7 s per dynamics, with the use of bidirectional SENSE acceleration of up to R = 9.The FCE design of the transmit coil easily accommodates the addition of a sixteen channel array coil. The improved spatial and temporal resolution provided by the high-field array coil with FCE dual-channel transmit will ultimately be beneficial in lesion detection and characterization.

  10. Manufacturing development of the Westinghouse Nb3Sn coil for the Large Coil Test Program

    International Nuclear Information System (INIS)

    Young, J.L.; Vota, T.L.; Singh, S.K.

    1983-01-01

    The Westinghouse Nb 3 Sn Magnet for the Oak Ridge National Laboratory Large Coil Program (LCP) is currently well into the manufacturing phase. This paper identifies the manufacturing processes and development tasks for his unique, advanced coil

  11. Optimization of the ECT background coil

    International Nuclear Information System (INIS)

    Ballou, J.K.; Luton, J.N.

    1975-01-01

    This study was begun to optimize the Eccentric Coil Test (ECT) background coil. In the course of this work a general optimization code was obtained, tested, and applied to the ECT problem. So far this code has proven to be very satisfactory. The results obtained with this code and earlier codes have illustrated the parametric behavior of such a coil system and that the optimum for this type system is broad. This study also shows that a background coil with a winding current density of less than 3000 A/cm 2 is not feasible for the ECT models presented in this paper

  12. Magnetic field coil in nuclear fusion device

    International Nuclear Information System (INIS)

    Yamaguchi, Mitsugi; Takano, Hirohisa.

    1975-01-01

    Object: To provide an electrical-insulatively stabilized magnetic field coil in nuclear fusion device, restraining an increase in voltage when plasma current is rapidly changed. Structure: A magnetic field coil comprises coils arranged coaxial with respective vacuum vessels, said coils being wound in positive and reverse polarities so as to form a vertical magnetic field within the plasma. The coils of the positive polarity are arranged along the vacuum vessel inside of an axis vertical in section of the annular plasma and are arranged symmetrically up and down of a horizontal axis. On the other hand, the coils of the reverse polarity are arranged along the vacuum vessel outside of a vertical axis and arranged symmetrically up and down of the horizontal axis. These positive and reverse polarity coils are alternately connected in series, and lead portions of the coils are connected to a power source by means of connecting wires. In this case, lead positions of the coils are arranged in one direction, and the connecting wires are disposed in closely contact relation to offset magnetic fields formed by the connecting wires each other. (Kawakami, Y.)

  13. A precise technique for manufacturing correction coil

    International Nuclear Information System (INIS)

    Schieber, L.

    1992-01-01

    An automated method of manufacturing correction coils has been developed which provides a precise embodiment of the coil design. Numerically controlled machines have been developed to accurately position coil windings on the beam tube. Two types of machines have been built. One machine bonds the wire to a substrate which is wrapped around the beam tube after it is completed while the second machine bonds the wire directly to the beam tube. Both machines use the Multiwire reg-sign technique of bonding the wire to the substrate utilizing an ultrasonic stylus. These machines are being used to manufacture coils for both the SSC and RHIC

  14. Tesla coil theoretical model and experimental verification

    OpenAIRE

    Voitkans, Janis; Voitkans, Arnis

    2014-01-01

    Abstract – In this paper a theoretical model of a Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wired format, where the line voltage is measured against electrically neutral space. It is shown that equivalent two-wired scheme can be found for a single-wired scheme and already known long line theory can be applied to a Tesla coil. Formulas for calculation of voltage in a Tesla coil by coordinate and calculation of resonance fre...

  15. The energizing of a NMR superconducting coil by a superconducting rectifier

    International Nuclear Information System (INIS)

    Sikkenga, J.; ten Kate, H.H.J.; van der Klundert, L.J.M.; Knoben, J.; Kraaij, G.J.; Spuorenberg, C.J.G.

    1985-01-01

    NMR magnets require a good homogeneity within a certain volume and an excellent field stability. The homogeneity can be met using a superconducting shim coil system. The field stability requires a constant current, although in many cases the current decay time constant is too low, due to imperfections in the superconducting wire and joints. This can be overcome using a rectifier. The rectifier can also be used to load the coil. The combination and interaction of the superconducting NMR coil (2.0 Tesla and 0.35 m cold bore) and the rectifier (20 W / 1 kA) is tested. The safety of the system is discussed. The shim coil system can compensate the strayfield of the rectifier. The field decay compensation will be discussed

  16. Attenuation correction for flexible magnetic resonance coils in combined magnetic resonance/positron emission tomography imaging.

    Science.gov (United States)

    Eldib, Mootaz; Bini, Jason; Calcagno, Claudia; Robson, Philip M; Mani, Venkatesh; Fayad, Zahi A

    2014-02-01

    Attenuation correction for magnetic resonance (MR) coils is a new challenge that came about with the development of combined MR and positron emission tomography (PET) imaging. This task is difficult because such coils are not directly visible on either PET or MR acquisitions with current combined scanners and are therefore not easily localized in the field of view. This issue becomes more evident when trying to localize flexible MR coils (eg, cardiac or body matrix coil) that change position and shape from patient to patient and from one imaging session to another. In this study, we proposed a novel method to localize and correct for the attenuation and scatter of a flexible MR cardiac coil, using MR fiducial markers placed on the surface of the coil to allow for accurate registration of a template computed tomography (CT)-based attenuation map. To quantify the attenuation properties of the cardiac coil, a uniform cylindrical water phantom injected with 18F-fluorodeoxyglucose (18F-FDG) was imaged on a sequential MR/PET system with and without the flexible cardiac coil. After establishing the need to correct for the attenuation of the coil, we tested the feasibility of several methods to register a precomputed attenuation map to correct for the attenuation. To accomplish this, MR and CT visible markers were placed on the surface of the cardiac flexible coil. Using only the markers as a driver for registration, the CT image was registered to the reference image through a combination of rigid and deformable registration. The accuracy of several methods was compared for the deformable registration, including B-spline, thin-plate spline, elastic body spline, and volume spline. Finally, we validated our novel approach both in phantom and patient studies. The findings from the phantom experiments indicated that the presence of the coil resulted in a 10% reduction in measured 18F-FDG activity when compared with the phantom-only scan. Local underestimation reached 22% in

  17. Evaluation of feasibility of 1.5 Tesla prostate MRI using body coil RF transmit in a patient with an implanted vagus nerve stimulator.

    Science.gov (United States)

    Favazza, Christopher P; Edmonson, Heidi A; Ma, Chi; Shu, Yunhong; Felmlee, Joel P; Watson, Robert E; Gorny, Krzysztof R

    2017-11-01

    To assess risks of RF-heating of a vagus nerve stimulator (VNS) during 1.5 T prostate MRI using body coil transmit and to compare these risks with those associated with MRI head exams using a transmit/receive head coil. Spatial distributions of radio-frequency (RF) B1 fields generated by transmit/receive (T/R) body and head coils were empirically assessed along the long axis of a 1.5 T MRI scanner bore. Measurements were obtained along the center axis of the scanner and laterally offset by 15 cm (body coil) and 7 cm (head coil). RF-field measurements were supplemented with direct measurements of RF-heating of 15 cm long copper wires affixed to and submerged in the "neck" region of the gelled saline-filled (sodium chloride and polyacrylic acid) "head-and-torso" phantom. Temperature elevations at the lead tips were measured using fiber-optic thermometers with the phantom positioned at systematically increased distances from the scanner isocenter. B1 field measurements demonstrated greater than 10 dB reduction in RF power at distances beyond 28 cm and 24 cm from isocenter for body and head coil, respectively. Moreover, RF power from body coil transmit at distances greater than 32 cm from isocenter was found to be lower than from the RF power from head coil transmit measured at locations adjacent to the coil array at its opening. Correspondingly, maximum temperature elevations at the tips of the copper wires decreased with increasing distance from isocenter - from 7.4°C at 0 cm to no appreciable heating at locations beyond 40 cm. For the particular scanner model evaluated in this study, positioning an implanted VNS farther than 32 cm from isocenter (configuration achievable for prostate exams) can reduce risks of RF-heating resulting from the body coil transmit to those associated with using a T/R head coil. © 2017 American Association of Physicists in Medicine.

  18. Superconducting Coil of Po Dipole

    CERN Multimedia

    1983-01-01

    The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam P0. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench.After this successful test up to its nominal field of 4.2 T, the power was not raised to reach a quench. The magnet was not installed in a beam and had no other further use. Nevertheless its construction provided knowledges and experience which became useful in the design and construction of the LHC magnets. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8211532X.

  19. Multicoil2: predicting coiled coils and their oligomerization states from sequence in the twilight zone.

    Directory of Open Access Journals (Sweden)

    Jason Trigg

    Full Text Available The alpha-helical coiled coil can adopt a variety of topologies, among the most common of which are parallel and antiparallel dimers and trimers. We present Multicoil2, an algorithm that predicts both the location and oligomerization state (two versus three helices of coiled coils in protein sequences. Multicoil2 combines the pairwise correlations of the previous Multicoil method with the flexibility of Hidden Markov Models (HMMs in a Markov Random Field (MRF. The resulting algorithm integrates sequence features, including pairwise interactions, through multinomial logistic regression to devise an optimized scoring function for distinguishing dimer, trimer and non-coiled-coil oligomerization states; this scoring function is used to produce Markov Random Field potentials that incorporate pairwise correlations localized in sequence. Multicoil2 significantly improves both coiled-coil detection and dimer versus trimer state prediction over the original Multicoil algorithm retrained on a newly-constructed database of coiled-coil sequences. The new database, comprised of 2,105 sequences containing 124,088 residues, includes reliable structural annotations based on experimental data in the literature. Notably, the enhanced performance of Multicoil2 is evident when tested in stringent leave-family-out cross-validation on the new database, reflecting expected performance on challenging new prediction targets that have minimal sequence similarity to known coiled-coil families. The Multicoil2 program and training database are available for download from http://multicoil2.csail.mit.edu.

  20. Design of the coolant system for the Large Coil Test Facility pulse coils

    International Nuclear Information System (INIS)

    Bridgman, C.; Ryan, T.L.

    1983-01-01

    The pulse coils will be a part of the Large Coil Test Facility in Oak Ridge, Tennessee, which is designed to test six large tokamak-type superconducting coils. The pulse coil set consists of two resistive coaxial solenoid coils, mounted so that their magnetic axis is perpendicular to the toroidal field lines of the test coil. The pulse coils provide transient vertical fields at test coil locations to simulate the pulsed vertical fields present in tokamak devices. The pulse coils are designed to be pulsed for 30 s every 150 s, which results in a Joule heating of 116 kW per coil. In order to provide this capability, the pulse coil coolant system is required to deliver 6.3 L/s (100 gpm) of subcooled liquid nitrogen at 10-atm absolute pressure. The coolant system can also cool down each pulse coil from room temperature to liquid nitrogen temperature. This paper provides details of the pumping and heat exchange equipment designed for the coolant system and of the associated instrumentation and controls

  1. Head Lice

    Science.gov (United States)

    ... nits. You should also use hot water to wash any bed linens, towels, and clothing recently worn by the person who had head lice. Vacuum anything that can’t be washed, such as the couch, carpets, your child’s car seat, and any stuffed animals. Because head lice ...

  2. Outcomes with single-coil versus dual-coil implantable cardioverter defibrillators: a meta-analysis.

    Science.gov (United States)

    Sunderland, Nicholas; Kaura, Amit; Murgatroyd, Francis; Dhillon, Para; Scott, Paul A

    2018-03-01

    Dual-coil implantable cardioverter defibrillator (ICD) leads have traditionally been used over single-coil leads due to concerns regarding high defibrillation thresholds (DFT) and consequent poor shock efficacy. However, accumulating evidence suggests that this position may be unfounded and that dual-coil leads may also be associated with higher complication rates during lead extraction. This meta-analysis collates data comparing dual- and single-coil ICD leads. Electronic databases were systematically searched for randomized controlled trials (RCT) and non-randomized studies comparing single-coil and dual-coil leads. The mean differences in DFT and summary estimates of the odds-ratio (OR) for first-shock efficacy and the hazard-ratio (HR) for all-cause mortality were calculated using random effects models. Eighteen studies including a total of 138,124 patients were identified. Dual-coil leads were associated with a lower DFT compared to single coil leads (mean difference -0.83J; 95% confidence interval [CI] -1.39--0.27; P = 0.004). There was no difference in the first-shock success rate with dual-coil compared to single-coil leads (OR 0.74; 95%CI 0.45-1.21; P=0.22). There was a significantly lower risk of all-cause mortality associated with single-coil leads (HR 0.91; 95%CI 0.86-0.95; P dual-coil leads. The mortality benefit with single-coil leads most likely represents patient selection bias. Given the increased risk and complexity of extracting dual-coil leads, centres should strongly consider single-coil ICD leads as the lead of choice for routine new left-sided ICD implants. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

  3. Rapid jetting status inspection and accurate droplet volume measurement for a piezo drop-on-demand inkjet print head using a scanning mirror for display applications

    Science.gov (United States)

    Shin, Dong-Youn; Kim, Minsung

    2017-02-01

    Despite the inherent fabrication simplicity of piezo drop-on-demand inkjet printing, the non-uniform deposition of colourants or electroluminescent organic materials leads to faulty display products, and hence, the importance of rapid jetting status inspection and accurate droplet volume measurement increases from a process perspective. In this work, various jetting status inspections and droplet volume measurement methods are reviewed by discussing their advantages and disadvantages, and then, the opportunities for the developed prototype with a scanning mirror are explored. This work demonstrates that jetting status inspection of 384 fictitious droplets can be performed within 17 s with maximum and minimum measurement accuracies of 0.2 ± 0.5 μ m for the fictitious droplets of 50 μ m in diameter and -1.2 ± 0.3 μ m for the fictitious droplets of 30 μ m in diameter, respectively. In addition to the new design of an inkjet monitoring instrument with a scanning mirror, two novel methods to accurately measure the droplet volume by amplifying a minute droplet volume difference and then converting to other physical properties are suggested and the droplet volume difference of ±0.3% is demonstrated to be discernible using numerical simulations, even with the low measurement accuracy of 1 μ m . When the fact is considered that the conventional vision-based method with a CCD camera requires the optical measurement accuracy less than 25 nm to measure the volume of an in-flight droplet in the nominal diameter of 50 μ m at the same volume measurement accuracy, the suggested method with the developed prototype offers a whole new opportunity to inkjet printing for display applications.

  4. Toroidal field coils for the PDX machine

    International Nuclear Information System (INIS)

    Bushnell, C.W.

    1975-01-01

    This paper describes the engineering design features of the TF coils for the PDX machine. Included are design details of the electrical insulation, water cooling, and coil segment joint which allows access to the central machine area. A discussion of the problems anticipated in the manufacture and the planned solutions are presented

  5. Operator coil monitoring Acceptance Test Procedure

    International Nuclear Information System (INIS)

    Erhart, M.F.

    1995-01-01

    The readiness of the Data Acquisition and Control System (DACS) to provide monitoring and control of the Programmable Logic Controller (PLC) abort coils from the Master and RSS stations will be systematically tested during performance of this procedure. It should be noted that these are not physical abort coils but software coils controlled by the software's ladder logic. The readiness of the DACS to properly interface with the ENRAF wire level gauge installed in the SY-101 storage tank will also be tested. During this test, a verification of all abort coil indications will be conducted at the DACS Development Facility in the 306E Building by injecting an input signal for each DACS sensor that has an associated abort coil until the abort coil actuates, and then ensuring that the status of the abort coil indicated at the Master and RSS stations is correct. Each abort coil will also be tested to ensure that the ''ENABLE'' and ''DISABLE'' controls from the Master and RSS stations function correctly, and only with the use of proper passwords

  6. Coil Optimization for High Temperature Superconductor Machines

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Jensen, Bogi Bech; Abrahamsen, Asger Bech

    2011-01-01

    This paper presents topology optimization of HTS racetrack coils for large HTS synchronous machines. The topology optimization is used to acquire optimal coil designs for the excitation system of 3 T HTS machines. Several tapes are evaluated and the optimization results are discussed. The optimiz...

  7. Novel transcranial magnetic stimulation coil for mice

    Science.gov (United States)

    March, Stephen; Stark, Spencer; Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2014-03-01

    Transcranial magnetic stimulation (TMS) shows potential for non-invasive treatment of various neurological disorders. Significant work has been performed on the design of coils used for TMS on human subjects but few reports have been made on the design of coils for use on the brains of animals such as mice. This work is needed as TMS studies utilizing mice can allow rapid preclinical development of TMS for human disorders but the coil designs developed for use on humans are inadequate for optimal stimulation of the much smaller mouse brain. A novel TMS coil has been developed with the goal of inducing strong and focused electric fields for the stimulation of small animals such as mice. Calculations of induced electric fields were performed utilizing an MRI derived inhomogeneous model of an adult male mouse. Mechanical and thermal analysis of this new TMS helmet-coil design have also been performed at anticipated TMS operating conditions to ensure mechanical stability of the new coil and establish expected linear attraction and rotational force values. Calculated temperature increases for typical stimulation periods indicate the helmet-coil system is capable of operating within established medical standards. A prototype of the coil has been fabricated and characterization results are presented.

  8. Evidence-based pathology: umbilical cord coiling.

    Science.gov (United States)

    Khong, T Y

    2010-12-01

    The generation of a pathology test result must be based on criteria that are proven to be acceptably reproducible and clinically relevant to be evidence-based. This review de-constructs the umbilical cord coiling index to illustrate how it can stray from being evidence-based. Publications related to umbilical cord coiling were retrieved and analysed with regard to how the umbilical coiling index was calculated, abnormal coiling was defined and reference ranges were constructed. Errors and other influences that can occur with the measurement of the length of the umbilical cord or of the number of coils can compromise the generation of the coiling index. Definitions of abnormal coiling are not consistent in the literature. Reference ranges defining hypocoiling or hypercoiling have not taken those potential errors or the possible effect of gestational age into account. Even the way numerical test results in anatomical pathology are generated, as illustrated by the umbilical coiling index, warrants a critical analysis into its evidence base to ensure that they are reproducible or free from errors.

  9. Composite coils for toroidal field coils and method of using same

    International Nuclear Information System (INIS)

    Perkins, R. G.; Trujillo, S. M.

    1985-01-01

    A composite toroidal field (TF) generating means consisting of segmented magnetic coil windings is disclosed. Each coil winding of the TF generating means consists of a copper or copper alloy conductor segment and an aluminum or aluminum alloy conductor segment. The conductor segments are joined at a high strength, low electrical resistance joint and the joint may either be a mechanical or metallurgical one. The use of the aluminum or aluminum alloy conductor segments improves the neutron economy of the reactor with which the TF coil is associated and reduces TF coil nuclear heating and heating gradients, and activation in the TF coils

  10. Startup of Large Coil Test Facility

    International Nuclear Information System (INIS)

    Haubenreich, P.N.; Bohanan, R.E.; Fietz, W.A.; Luton, J.N.; May, J.R.

    1984-01-01

    The Large Coil Test Facility (LCTF) is being used to test superconducting toroidal field coils about one-third the size of those for INTOR. Eventually, six different coils from four countries will be tested. Operations began in 1983 with acceptance testing of the helium refrigerator/liquefier system. Comprehensive shakedown of the facility and tests with the first three coils (from Japan, the United States, and Switzerland) were successfully accomplished in the summer of 1984. Currents up to 10,200 A and fields up to 6.4 T were reached. Data were obtained on performance of refrigerator, helium distribution, power supplies, controls, and data acquisition systems and on the acoustic emission, voltages, currents, and mechanical strains during charging and discharging the coils

  11. Startup of Large Coil Test Facility

    International Nuclear Information System (INIS)

    Haubenreich, P.N.; Bohanan, R.E.; Fietz, W.A.; Luton, J.N.; May, J.R.

    1985-01-01

    The Large Coil Test Facility (LCTF) is being used to test superconducting toroidal field coils about one-third the size of those for INTOR. Eventually, six different coils from four countries will be tested. Operations began in 1983 with acceptance testing of the helium refrigerator/liquefier system. Comprehensive shakedown of the facility and tests with the first three coils (from Japan, the United States, and Switzerland) were successfully accomplished in the summer of 1984. Currents up to 10,200 A and fields up to 6.4 T were reached. Data were obtained on performance of refrigerator, helium distribution, power supplies, controls, and data acquisition systems and on the acoustic emission, voltages, currents, and mechanical strains during charging and discharging the coils

  12. Helically coiled tube heat exchanger

    International Nuclear Information System (INIS)

    Harris, A.M.

    1981-01-01

    In a heat exchanger such as a steam generator for a nuclear reactor, two or more bundles of helically coiled tubes are arranged in series with the tubes in each bundle integrally continuing through the tube bundles arranged in series therewith. Pitch values for the tubing in any pair of tube bundles, taken transverse to the path of the reactor coolant flow about the tubes, are selected as a ratio of two unequal integers to permit efficient operation of each tube bundle while maintaining the various tube bundles of the heat exchanger within a compact envelope. Preferably, the helix angle and tube pitch parallel to the path of coolant flow are constant for all tubes in a single bundle so that the tubes are of approximately the same length within each bundle

  13. Effects of passive coils on spheromak gross MHD instabilities

    International Nuclear Information System (INIS)

    Munson, C.; Janos, A.; Paul, S.; Wysocki, F.; Yamada, M.

    1983-01-01

    The experimental investigation of the effectiveness of figure-8 coils in stabilizing the n=1 tilting mode of spheromak plasmas in Proto S-1 A/B is extended. In addition, another coil configuration, the saddle coil, is examined

  14. Localized 31PNMR spectroscopy with ISIS and surface coils

    International Nuclear Information System (INIS)

    Heindel, W.; Schreier, G.; Steinbrich, W.; Glathe, S.; Huttmann, P.

    1990-01-01

    A new method for image-guided localized phosphorus NMR spectroscopy of superficial tissues has been investigated using a 1.5 Tesla whole-body-MR-system. We used a surface coil combined with adiabatic excitation pulses and a modified ISIS sequence. This approach is related to imaging sequences and thus permits a flexible and accurate determination of the volume of interest from 'conventional' proton images. The scope and advantages of the method are demonstrated by phantom studies. Clinical applications to the liver, renal transplants, and the mediastinum are described. (orig.) [de

  15. The ultimate intrinsic signal-to-noise ratio of loop- and dipole-like current patterns in a realistic human head model.

    Science.gov (United States)

    Pfrommer, Andreas; Henning, Anke

    2018-03-13

    The ultimate intrinsic signal-to-noise ratio (UISNR) represents an upper bound for the achievable SNR of any receive coil. To reach this threshold a complete basis set of equivalent surface currents is required. This study systematically investigated to what extent either loop- or dipole-like current patterns are able to reach the UISNR threshold in a realistic human head model between 1.5 T and 11.7 T. Based on this analysis, we derived guidelines for coil designers to choose the best array element at a given field strength. Moreover, we present ideal current patterns yielding the UISNR in a realistic body model. We distributed generic current patterns on a cylindrical and helmet-shaped surface around a realistic human head model. We excited electromagnetic fields in the human head by using eigenfunctions of the spherical and cylindrical Helmholtz operator. The electromagnetic field problem was solved by a fast volume integral equation solver. At 7 T and above, adding curl-free current patterns to divergence-free current patterns substantially increased the SNR in the human head (locally >20%). This was true for the helmet-shaped and the cylindrical surface. On the cylindrical surface, dipole-like current patterns had high SNR performance in central regions at ultra-high field strength. The UISNR increased superlinearly with B0 in most parts of the cerebrum but only sublinearly in the periphery of the human head. The combination of loop and dipole elements could enhance the SNR performance in the human head at ultra-high field strength. © 2018 International Society for Magnetic Resonance in Medicine.

  16. Head Injuries

    Science.gov (United States)

    ... a severe blow to the head can still knock the brain into the side of the skull ... following certain precautions and taking a break from sports and other activities that make symptoms worse. Playing ...

  17. Characterization and evaluation of a flexible MRI receive coil array for radiation therapy MR treatment planning using highly decoupled RF circuits

    Science.gov (United States)

    McGee, Kiaran P.; Stormont, Robert S.; Lindsay, Scott A.; Taracila, Victor; Savitskij, Dennis; Robb, Fraser; Witte, Robert J.; Kaufmann, Timothy J.; Huston, John, III; Riederer, Stephen J.; Borisch, Eric A.; Rossman, Phillip J.

    2018-04-01

    The growth in the use of magnetic resonance imaging (MRI) data for radiation therapy (RT) treatment planning has been facilitated by scanner hardware and software advances that have enabled RT patients to be imaged in treatment position while providing morphologic and functional assessment of tumor volumes and surrounding normal tissues. Despite these advances, manufacturers have been slow to develop radiofrequency (RF) coils that closely follow the contour of a RT patient undergoing MR imaging. Instead, relatively large form surface coil arrays have been adapted from diagnostic imaging. These arrays can be challenging to place on, and in general do not conform to the patient’s body habitus, resulting in sub optimal image quality. The purpose of this study is to report on the characterization of a new flexible and highly decoupled RF coil for use in MR imaging of RT patients. Coil performance was evaluated by performing signal-to-noise ratio (SNR) and noise correlation measurements using two coil (SNR) and four coil (noise correlation) element combinations as a function of coil overlap distance and comparing these values to those obtained using conventional coil elements. In vivo testing was performed in both normal volunteers and patients using a four and 16 element RF coil. Phantom experiments demonstrate the highly decoupled nature of the new coil elements when compared to conventional RF coils, while in vivo testing demonstrate that these coils can be integrated into extremely flexible and form fitting substrates that follow the exact contour of the patient. The new coil design addresses limitations imposed by traditional surface coil arrays and have the potential to significantly impact MR imaging for both diagnostic and RT applications.

  18. A Flexible Nested Sodium and Proton Coil Array with Wideband Matching for Knee Cartilage MRI at 3 Tesla

    Science.gov (United States)

    Brown, Ryan; Lakshmanan, Karthik; Madelin, Guillaume; Alon, Leeor; Chang, Gregory; Sodickson, Daniel K.; Regatte, Ravinder R.; Wiggins, Graham C.

    2015-01-01

    Purpose We describe a 6×2 channel sodium/proton array for knee MRI at 3 Tesla. Multi-element coil arrays are desirable because of well-known signal-to-noise ratio advantages over volume and single-element coils. However, low coil-tissue coupling that is characteristic of coils operating at low frequency can make the potential gains from a phased array difficult to realize. Methods The issue of low coil-tissue coupling in the developed six channel sodium receive array was addressed by implementing 1) a mechanically flexible former to minimize coil-to-tissue distance and reduce the overall diameter of the array and 2) a wideband matching scheme that counteracts preamplifier noise degradation caused by coil coupling and a high quality factor. The sodium array was complemented with a nested proton array to enable standard MRI. Results The wideband matching scheme and tight-fitting mechanical design contributed to greater than 30% central SNR gain on the sodium module over a mono-nuclear sodium birdcage coil, while the performance of the proton module was sufficient for clinical imaging. Conclusion We expect the strategies presented in this work to be generally relevant in high density receive arrays, particularly in x-nuclei or small animal applications, or in those where the array is distant from the targeted tissue. PMID:26502310

  19. Comparison of the effectiveness of preoperative portal vein embolization in patients with chronic liver disease: Gelfoam versus gelfoam coil

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sung Wook; Chang, Il Soo; Do, Young Soo; Park, Hong Suk; Park, Kwang Bo; Cho, Sung Ki; Choo, In Wook [Dept. of Radiology, and Cardiac and Vascular Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Choo, Sung Wook [Dept. of Radiology, Konkuk University School of Medicine, Seoul (Korea, Republic of)

    2015-05-15

    To compare the effectiveness of portal vein embolization (PVE) performed using gelfoam or a gelfoam-coil combination before major hepatic resection in patients with chronic liver disease. PVE using gelfoam or a gelfoam-coil combination was performed in 37 patients. From April 2003 to September 2007, PVE was performed using gelfoam (n = 17) and a gelfoam-coil combination (n = 20) to induce hypertrophy. Computed tomography volumetry was performed 2-4 weeks after PVE to assess the changes in liver volume. The mean percentage increase in future liver remnant volume was 23.7 +/- 23.7% in the gelfoam group and 36.7 +/- 18.5% in the gelfoam-coil group (p = 0.02). Recanalization was found in 15 gelfoam group patients and 8 gelfoam-coil group patients (p = 0.003). The mean tumor size increased from 4.5 +/- 2.9 cm before PVE to 5.0 +/- 3.5 cm after PVE in the gelfoam group and from 4.3 +/- 2.2 cm before PVE to 4.7 +/- 2.5 cm after PVE in the gelfoam-coil group (p = 0.80). The gelfoam-coil combination was more effective than gelfoam alone for induction of compensatory hypertrophy by PVE in patients with chronic liver disease.

  20. Switching transients in a superconducting coil

    International Nuclear Information System (INIS)

    Owen, E.W.; Shimer, D.W.

    1983-01-01

    A study is made of the transients caused by the fast dump of large superconducting coils. Theoretical analysis, computer simulation, and actual measurements are used. Theoretical analysis can only be applied to the simplest of models. In the computer simulations two models are used, one in which the coil is divided into ten segments and another in which a single coil is employed. The circuit breaker that interrupts the current to the power supply, causing a fast dump, is represented by a time and current dependent conductance. Actual measurements are limited to measurements made incidental to performance tests on the MFTF Yin-yang coils. It is found that the breaker opening time is the critical factor in determining the size and shape of the transient. Instantaneous opening of the breaker causes a lightly damped transient with large amplitude voltages to ground. Increasing the opening time causes the transient to become a monopulse of decreasing amplitude. The voltages at the external terminals are determined by the parameters of the external circuit. For fast opening times the frequency depends on the dump resistor inductance, the circuit capacitance, and the amplitude on the coil current. For slower openings the dump resistor inductance and the current determine the amplitude of the voltage to ground at the terminals. Voltages to ground are less in the interior of the coil, where transients related to the parameters of the coil itself are observed

  1. Correcting coils in end magnets of accelerators

    Directory of Open Access Journals (Sweden)

    L. R. P. Kassab

    1998-05-01

    Full Text Available We present an empirical investigation of the correcting coils behavior used to homogenize the field distribution of the race-track microtron accelerator end magnets. These end magnets belong to the second stage of the 30.0 MeV cw electron accelerator under construction at IFUSP, the race-track microtron booster, in which the beam energy is raised from 1.97 to 5.1 MeV. The correcting coils are attached to the pole faces and are based on the inhomogeneities of the magnetic field measured. The performance of these coils, when operating the end magnets with currents that differ by ±10% from the one used in the mappings that originated the coils copper leads, is presented. For one of the magnets, adjusting conveniently the current of the correcting coils makes it possible to homogenize field distributions of different intensities, once their shapes are practically identical to those that originated the coils. For the other one, the shapes are changed and the coils are less efficient. This is related to intrinsic factors that determine the inhomogeneities. However, we obtained uniformity of 0.001% in both cases.

  2. Routine phasing of coiled-coil protein crystal structures with AMPLE

    Directory of Open Access Journals (Sweden)

    Jens M. H. Thomas

    2015-03-01

    Full Text Available Coiled-coil protein folds are among the most abundant in nature. These folds consist of long wound α-helices and are architecturally simple, but paradoxically their crystallographic structures are notoriously difficult to solve with molecular-replacement techniques. The program AMPLE can solve crystal structures by molecular replacement using ab initio search models in the absence of an existent homologous protein structure. AMPLE has been benchmarked on a large and diverse test set of coiled-coil crystal structures and has been found to solve 80% of all cases. Successes included structures with chain lengths of up to 253 residues and resolutions down to 2.9 Å, considerably extending the limits on size and resolution that are typically tractable by ab initio methodologies. The structures of two macromolecular complexes, one including DNA, were also successfully solved using their coiled-coil components. It is demonstrated that both the ab initio modelling and the use of ensemble search models contribute to the success of AMPLE by comparison with phasing attempts using single structures or ideal polyalanine helices. These successes suggest that molecular replacement with AMPLE should be the method of choice for the crystallographic elucidation of a coiled-coil structure. Furthermore, AMPLE may be able to exploit the presence of a coiled coil in a complex to provide a convenient route for phasing.

  3. PET attenuation correction for rigid MR Tx/Rx coils from 176Lu background activity

    Science.gov (United States)

    Lerche, Christoph W.; Kaltsas, Theodoris; Caldeira, Liliana; Scheins, Jürgen; Rota Kops, Elena; Tellmann, Lutz; Pietrzyk, Uwe; Herzog, Hans; Shah, N. Jon

    2018-02-01

    One challenge for PET-MR hybrid imaging is the correction for attenuation of the 511 keV annihilation radiation by the required RF transmit and/or RF receive coils. Although there are strategies for building PET transparent Tx/Rx coils, such optimised coils still cause significant attenuation of the annihilation radiation leading to artefacts and biases in the reconstructed activity concentrations. We present a straightforward method to measure the attenuation of Tx/Rx coils in simultaneous MR-PET imaging based on the natural 176Lu background contained in the scintillator of the PET detector without the requirement of an external CT scanner or PET scanner with transmission source. The method was evaluated on a prototype 3T MR-BrainPET produced by Siemens Healthcare GmbH, both with phantom studies and with true emission images from patient/volunteer examinations. Furthermore, the count rate stability of the PET scanner and the x-ray properties of the Tx/Rx head coil were investigated. Even without energy extrapolation from the two dominant γ energies of 176Lu to 511 keV, the presented method for attenuation correction, based on the measurement of 176Lu background attenuation, shows slightly better performance than the coil attenuation correction currently used. The coil attenuation correction currently used is based on an external transmission scan with rotating 68Ge sources acquired on a Siemens ECAT HR  +  PET scanner. However, the main advantage of the presented approach is its straightforwardness and ready availability without the need for additional accessories.

  4. Effects of coil orientation on the electric field induced by TMS over the hand motor area

    International Nuclear Information System (INIS)

    Laakso, Ilkka; Hirata, Akimasa; Ugawa, Yoshikazu

    2014-01-01

    Responses elicited by transcranial magnetic stimulation (TMS) over the hand motor area depend on the position and orientation of the stimulating coil. In this work, we computationally investigate the induced electric field for multiple coil orientations and locations in order to determine which parts of the brain are affected and how the sensitivity of motor cortical activation depends on the direction of the electric field. The finite element method is used for calculating the electric field induced by TMS in two individual anatomical models of the head and brain. The orientation of the coil affects both the strength and depth of penetration of the electric field, and the field strongly depends on the direction of the sulcus, where the target neurons are located. The coil position that gives the strongest electric field in the target cortical region may deviate from the closest scalp location by a distance on the order of 1 cm. Together with previous experimental data, the results support the hypothesis that the cortex is most sensitive to fields oriented perpendicular to the cortical layers, while it is relatively insensitive to fields parallel to them. This has important implications for targeting of TMS. To determine the most effective coil position and orientation, it is essential to consider both biological (the direction of the targeted axons) and physical factors (the strength and direction of the electric field). (paper)

  5. The precise adjustment of coil location for transcranial magnetic stimulation during dynamic motion.

    Science.gov (United States)

    Kitamura, Taku; Yaeshima, Katsutoshi; Yamamoto, Shin-Ichiro; Kawashima, Noritaka

    2013-01-01

    Transcranial magnetic stimulation (TMS) to the cerebral cortex is a major in vitro technique that is used in the field of neurophysiology. The magnitude of the motor-evoked potentials (MEP) that are elicited by TMS to the primary motor cortex reflect the excitability of the corticospinal pathway. MEPs are very sensitive to the scalp location of the stimulus coil, especially when corticospinal excitability is recorded during walking or other dynamic motions. In this study, we created a coil navigational system that consisted of three-dimensional motion analysis cameras, rigid bodies on the head and coil, and programming software. In order to evaluate the feasibility of the use of our system, pseudo TMS was applied during treadmill walking with or without the navigational system. As a result, we found that the variances due to coil location and/or distance from the target site were reduced with our system. This technique enabled us to realize high precision and accuracy in coil placement, even during dynamic motion.

  6. The application of micro-coil NMR probe technology to metabolomics of urine and serum

    International Nuclear Information System (INIS)

    Grimes, John H.; O’Connell, Thomas M.

    2011-01-01

    Increasing the sensitivity and throughput of NMR-based metabolomics is critical for the continued growth of this field. In this paper the application of micro-coil NMR probe technology was evaluated for this purpose. The most commonly used biofluids in metabolomics are urine and serum. In this study we examine different sample limited conditions and compare the detection sensitivity of the micro-coil with a standard 5 mm NMR probe. Sample concentration is evaluated as a means to leverage the greatly improved mass sensitivity of the micro-coil probes. With very small sample volumes, the sensitivity of the micro-coil probe does indeed provide a significant advantage over the standard probe. Concentrating the samples does improve the signal detection, but the benefits do not follow the expected linear increase and are both matrix and metabolite specific. Absolute quantitation will be affected by concentration, but an analysis of relative concentrations is still possible. The choice of the micro-coil probe over a standard tube based probe will depend upon a number of factors including number of samples and initial volume but this study demonstrates the feasibility of high-throughput metabolomics with the micro-probe platform.

  7. Internal trim coils for CBA superconducting magnets

    International Nuclear Information System (INIS)

    Thompson, P.A.; Aronson, S.; Cottingham, J.G.; Garber, M.; Hahn, H.; Sampson, W.B.

    1983-01-01

    In order to correct iron saturation effects and shape the beam working line, superconducting trim coils have been constructed, which operate inside the main coils. Detailed studies of mechanical properties, quench behavior, fields produced, and hysteresis have lead to the production of accelerator-quality coils generating the required-strength harmonics up to cos (7theta). These are routinely installed in CBA main magnets and operate at 80% of short sample with negligible training in an ambient field of more than 5.3T

  8. Superconducting coil development and motor demonstration: Overview

    Science.gov (United States)

    Gubser, D. U.

    1995-12-01

    Superconducting bismuth-cuprate wires, coils, and magnets are being produced by industry as part of a program to test the viability of using such magnets in Naval systems. Tests of prototype magnets, coils, and wires reveal progress in commercially produced products. The larger magnets will be installed in an existing superconducting homopolar motor and operated initially at 4.2K to test the performance. It is anticipated that approximately 400 Hp will be achieved by the motor. This article reports on the initial tests of the magnets, coils, and wires as well as the development program to improve their performance.

  9. CS model coil experimental log book

    International Nuclear Information System (INIS)

    Nishijima, Gen; Sugimoto, Makoto; Nunoya, Yoshihiko; Wakabayashi, Hiroshi; Tsuji, Hiroshi

    2001-02-01

    Charging test of the ITER CS Model Coil which is the world's largest superconducting pulse coil and the CS Insert Coil had started at April 11, 2000 and had completed at August 18, 2000. In the campaign, total shot numbers were 356 and the size of the data file in the DAS (Data Acquisition System) was over 20 GB. This report is a database that consists of the log list and the log sheets of every shot. One can access the database, make a search, and browse results via Internet (http://1ogwww.naka.jaeri.go.jp). The database will be useful to quick search to choose necessary shots. (author)

  10. Large magnetic coils for fusion technology

    International Nuclear Information System (INIS)

    Komarek, P.; Ulbricht, A.

    1989-01-01

    This paper reviews the current status of research in this field and outlines future tasks and experiments for the Next European Torus (NET). Research and development work accomplished so far permits generation and safe operation of magnetic fields up to 9 T by means of NbTi coils. Fields up to 11 T are feasible if the coils are cooled with superfluid helium at 1.8 K. The potential of the Nb 3 Sn coils promise achievement of magnetic fields between 12 and 13 T. (MM) [de

  11. Design and Fabrication of the KSTAR Poloidal Field Coil Structure

    International Nuclear Information System (INIS)

    Park, H. K.; Choi, C. H.; Sa, J. W.

    2005-01-01

    The KSTAR magnet system consists of 16 toroidal field(TF) coils. 4 pairs of central solenoid(CS) coils, and 3 pairs of outer poloidal field(PF) coils. The TF coils are encased in a structure to enhance mechanical stability. The CS coil structure is supported on top of the TF coil structure and supplies a vertical compression of 15 MN to prevent lateral movement due to a repulsive force between the CS coils. The PF coil system is vertically symmetry to the machine mid-plane and consists of 6 coils and 80 support structures(i.e, 16 for PF5, 32 for PF6 and 32 fort PF7). All PF coil structures should absorb the thermal contraction difference between TF coil structure and PF coils due to cool down and endure the vertical and radial magnetic forces due to current charging. In order to satisfy these structural requirements. the PF5 coil structure is designed base on hinges and both of PF6 and PF7 coil structures based on flexible plates. The PF coil structures are assembled on the TF coil structure with an individual basement that is welded on the TF coil structure

  12. Flexible eddy current coil arrays

    International Nuclear Information System (INIS)

    Krampfner, Y.; Johnson, D.P.

    1987-01-01

    A novel approach was devised to overcome certain limitations of conventional eddy current testing. The typical single-element hand-wound probe was replaced with a two dimensional array of spirally wound probe elements deposited on a thin, flexible polyimide substrate. This provides full and reliable coverage of the test area and eliminates the need for scanning. The flexible substrate construction of the array allows the probes to conform to irregular part geometries, such as turbine blades and tubing, thereby eliminating the need for specialized probes for each geometry. Additionally, the batch manufacturing process of the array can yield highly uniform and reproducible coil geometries. The array is driven by a portable computer-based eddy current instrument, smartEDDY/sup TM/, capable of two-frequency operation, and offers a great deal of versatility and flexibility due to its software-based architecture. The array is coupled to the instrument via an 80-switch multiplexer that can be configured to address up to 1600 probes. The individual array elements may be addressed in any desired sequence, as defined by the software

  13. A coil test facility for the cryogenic tests of the JT-60SA TF coils

    International Nuclear Information System (INIS)

    Chantant, M.; Genini, L.; Bayetti, P.; Millet, F.; Wanner, M.; Massaut, V.; Corte, A. Della; Ardelier-Desage, F.; Catherine-Dumont, V.; Dael, A.; Decool, P.; Donati, A.; Duchateau, J.L.; Garibaldi, P.; Girard, S.; Hatchressian, J.C.; Fejoz, P.; Jamotton, P.; Jourdheuil, L.; Juster, F.P.

    2011-01-01

    In the framework of the Broader Approach Activities, the EU will deliver to Japan the 18 superconducting coils, which constitute the JT-60SA Toroidal field magnet. These 18 coils, manufactured by France and Italy, will be cold tested before shipping to Japan. For this purpose, the European Joint Undertaking for ITER, the Development of Fusion Energy ('Fusion for Energy', F4E) and the European Voluntary Contributors are collaborating to design and set-up a coil test facility (CTF) and to perform the acceptance test of the 18 JT-60SA Toroidal Field (TF) coils. The test facility is designed to test one coil at a time at nominal current and cryogenic temperature. The test of the first coil of each manufacturer includes a quench triggered by increasing the temperature. The project is presently in the detailed design phase.

  14. Coil measurement data acquisition and curing press control system for SSC dipole magnet coils

    International Nuclear Information System (INIS)

    Dickey, C.E.

    1989-03-01

    A coil matching program, similar in theory to the methods used to match Tevatron coils, is being developed at Fermilab. Modulus of elasticity and absolute coil size will be determined at 18-inch intervals along the coils while in the coil curing press immediately following the curing process. A data acquisition system is under construction to automatically acquire and manage the large quantities of data that result. Data files will be transferred to Fermilab's VAX Cluster for long-term storage and actual coil matching. The data acquisition system will also provide the control algorithm for the curing press hydraulic system. A description of the SSC Curing Press Data Acquisition and Controls System will be reported. 20 figs

  15. SU-E-J-231: Comparison of Delineation Variability of Soft Tissue Volume and Position in Head-And-Neck Between Two T1-Weighted Pulse Sequences Using An MR-Simulator with Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Wong, O; Lo, G; Yuan, J; Law, M; Ding, A; Cheng, K; Chan, K; Cheung, K; Yu, S [Hong Kong Sanatorium & Hospital, Hong Kong (Hong Kong)

    2015-06-15

    Purpose: There is growing interests in applying MR-simulator(MR-sim) in radiotherapy but MR images subject to hardware, patient and pulse sequence dependent geometric distortion that may potentially influence target definition. This study aimed to evaluate the influence on head-and-neck tissue delineation, in terms of positional and volumetric variability, of two T1-weighted(T1w) MR sequences on a 1.5T MR-sim Methods: Four healthy volunteers were scanned (4 scans for each on different days) using both spin-echo (3DCUBE, TR/TE=500/14ms, TA=183s) and gradient-echo sequences (3DFSPGR, TE/TR=7/4ms, TA=173s) with identical coverage, voxel-size(0.8×0.8×1.0mm3), receiver-bandwidth(62.5kHz/pix) and geometric correction on a 1.5T MR-sim immobilized with personalized thermoplastic cast and head-rest. Under this setting, similar T1w contrast and signal-to-noise ratio were obtained, and factors other than sequence that might bias image distortion and tissue delineation were minimized. VOIs of parotid gland(PGR, PGL), pituitary gland(PIT) and eyeballs(EyeL, EyeR) were carefully drawn, and inter-scan coefficient-of-variation(CV) of VOI centroid position and volume were calculated for each subject. Mean and standard deviation(SD) of the CVs for four subjects were compared between sequences using Wilcoxon ranksum test. Results: The mean positional(<4%) and volumetric(<7%) CVs varied between tissues, majorly dependent on tissue inherent properties like volume, location, mobility and deformability. Smaller mean volumetric CV was found in 3DCUBE, probably due to its less proneness to tissue susceptibility, but only PGL showed significant difference(P<0.05). Positional CVs had no significant differences for all VOIs(P>0.05) between sequences, suggesting volumetric variation might be more sensitive to sequence-dependent delineation difference. Conclusion: Although 3DCUBE is considered less prone to tissue susceptibility-induced artifact and distortion, our preliminary data showed

  16. Design considerations for ITER toroidal field coils

    International Nuclear Information System (INIS)

    Kalsi, S.S.; Lousteau, D.C.; Miller, J.R.

    1987-01-01

    The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Europe, Japan, the Union of Soviet Socialist Republics (U.S.S.R.), and the United States. This paper describes a magnetic and mechanical design methodology for toroidal field (TF) coils that employs Nb 3 Sn superconductor technology. Coil winding is sized by using conductor concepts developed for the U.S. TIBER concept. Manifold concepts are presented for the complete cooling system. Also included are concepts for the coil structural arrangement. The effects of in-plane and out-of-plane loads are included in the design considerations for the windings and case. Concepts are presented for reacting these loads with a minimum amount of additional structural material. Concepts discussed in this paper could be considered for the ITER TF coils

  17. 12 tesla test coil. Annual progress report

    International Nuclear Information System (INIS)

    1979-01-01

    The Plasma Fusion Center at MIT has been charged with responsibility for the design, development, fabrication and test operation of a Niobium-3-Tin Superconducting Test Coil. Research is described on DOE's 12 tesla coil demonstration program in which several one-meter diameter superconducting test coils will be inserted and tested in DOE's High Field Test Facility at the Lawrence Livermore Laboratories. The work was initiated at the start of FY 79. FY 79 saw the completion of our Preliminary Design and the initiation of three (3) subcontracts: (1) Westinghouse review of the Preliminary Design, (II) Supercon, Inc. development of a tubular copper matrix, Nb 3 Sn Superconductor and (III) Airco optimization of the LCP-W Nb 3 Sn superconductor for 12T service. In addition, Airco was charged with the production of a 1000 foot length of model 15,000A conductor. Coil winding exercises were initiated at the Everson Electric Company

  18. OCLATOR (One Coil Low Aspect Toroidal Reactor)

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, S.

    1980-02-01

    A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the ..beta.. limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR (One Coil Low Aspect Toroidal Reactor).

  19. Advanced Singlet Oxygen Generator for a COIL

    National Research Council Canada - National Science Library

    Kodymova, Jarmila; Zagidullin, M; Nikolaev, V; Svistun, M; Khvatov, N; Hruby, J; Spalek, O; Jirasek, V; Censsky, M

    2005-01-01

    This report results from a contract tasking Academy of Sciences as follows: The Grantee will develop new and radically different ideas for a high performance, advanced singlet oxygen generator for driving a supersonic COIL...

  20. Helium leak testing the Westinghouse LCP coil

    International Nuclear Information System (INIS)

    Merritt, P.A.; Attaar, M.H.; Hordubay, T.D.

    1983-01-01

    The tests, equipment, and techniques used to check the Westinghouse LCP coil for coolant flow path integrity and helium leakage are unique in terms of test sensitivity and application. This paper will discuss the various types of helium leak testing done on the LCP coil as it enters different stages of manufacture. The emphasis will be on the degree of test sensitivity achieved under shop conditions, and what equipment, techniques and tooling are required to achieve this sensitivity (5.9 x 10 -8 scc/sec). Other topics that will be discussed are helium flow and pressure drop testing which is used to detect any restrictions in the flow paths, and the LCP final acceptance test which is the final leak test performed on the coil prior to its being sent for testing. The overall allowable leak rate for this coil is 5 x 10 -6 scc/sec. A general evaluation of helium leak testing experience are included

  1. Radiative MRI Coil Design Using Parasitic Scatterers

    DEFF Research Database (Denmark)

    Sanchez-Heredia, Juan D.; Avendal, Johan; Bibic, Adnan

    2018-01-01

    allows for antenna design techniques to be adapted to RF coil designs. This study proposes the use of parasitic scatterers to improve the performance of an existing 7T MRI coil called the single-sided adapted dipole (SSAD) antenna. The results reveal that scatterers arranged in a Yagi fashion can......Conventionally, radiofrequency (RF) coils used for magnetic resonance imaging (MRI) are electrically small and designed for nearfield operation. Therefore, existing antenna design techniques are mostly irrelevant for RF coils. However, the use of higher frequencies in ultrahigh field (UHF) MRI...... be applied to reduce local specific absorption rate (SAR) maxima of a reference SSAD by 40% with only a 6% decrease in the propagated B1 + field at the tissue depth of 15 cm. The higher directivity of the proposed design also decreasing the coupling with additional elements, making this antenna...

  2. MR angiography after coiling of intracranial aneurysms

    NARCIS (Netherlands)

    Schaafsma, J.D.

    2012-01-01

    Introduction Endovascular occlusion with detachable coils has become an alternative treatment to neurosurgical clipping of intracranial aneurysms over the last two decades. Its minimal invasiveness is the most important advantage of this treatment compared to clipping. The disadvantage of occlusion

  3. SU-C-BRA-05: Delineating High-Dose Clinical Target Volumes for Head and Neck Tumors Using Machine Learning Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, C [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); The University of Texas Graduate School of Biomedical Sciences, Houston, TX (United States); Wong, A [Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); School of Medicine, The University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Mohamed, A; Fuller, C [Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Yang, J; Court, L; Aristophanous, M [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Rao, A [Department of Bioinformatics and Computational Biology, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To develop and test population-based machine learning algorithms for delineating high-dose clinical target volumes (CTVs) in H&N tumors. Automating and standardizing the contouring of CTVs can reduce both physician contouring time and inter-physician variability, which is one of the largest sources of uncertainty in H&N radiotherapy. Methods: Twenty-five node-negative patients treated with definitive radiotherapy were selected (6 right base of tongue, 11 left and 9 right tonsil). All patients had GTV and CTVs manually contoured by an experienced radiation oncologist prior to treatment. This contouring process, which is driven by anatomical, pathological, and patient specific information, typically results in non-uniform margin expansions about the GTV. Therefore, we tested two methods to delineate high-dose CTV given a manually-contoured GTV: (1) regression-support vector machines(SVM) and (2) classification-SVM. These models were trained and tested on each patient group using leave-one-out cross-validation. The volume difference(VD) and Dice similarity coefficient(DSC) between the manual and auto-contoured CTV were calculated to evaluate the results. Distances from GTV-to-CTV were computed about each patient’s GTV and these distances, in addition to distances from GTV to surrounding anatomy in the expansion direction, were utilized in the regression-SVM method. The classification-SVM method used categorical voxel-information (GTV, selected anatomical structures, else) from a 3×3×3cm3 ROI centered about the voxel to classify voxels as CTV. Results: Volumes for the auto-contoured CTVs ranged from 17.1 to 149.1cc and 17.4 to 151.9cc; the average(range) VD between manual and auto-contoured CTV were 0.93 (0.48–1.59) and 1.16(0.48–1.97); while average(range) DSC values were 0.75(0.59–0.88) and 0.74(0.59–0.81) for the regression-SVM and classification-SVM methods, respectively. Conclusion: We developed two novel machine learning methods to delineate

  4. SU-C-BRA-05: Delineating High-Dose Clinical Target Volumes for Head and Neck Tumors Using Machine Learning Algorithms

    International Nuclear Information System (INIS)

    Cardenas, C; Wong, A; Mohamed, A; Fuller, C; Yang, J; Court, L; Aristophanous, M; Rao, A

    2016-01-01

    Purpose: To develop and test population-based machine learning algorithms for delineating high-dose clinical target volumes (CTVs) in H&N tumors. Automating and standardizing the contouring of CTVs can reduce both physician contouring time and inter-physician variability, which is one of the largest sources of uncertainty in H&N radiotherapy. Methods: Twenty-five node-negative patients treated with definitive radiotherapy were selected (6 right base of tongue, 11 left and 9 right tonsil). All patients had GTV and CTVs manually contoured by an experienced radiation oncologist prior to treatment. This contouring process, which is driven by anatomical, pathological, and patient specific information, typically results in non-uniform margin expansions about the GTV. Therefore, we tested two methods to delineate high-dose CTV given a manually-contoured GTV: (1) regression-support vector machines(SVM) and (2) classification-SVM. These models were trained and tested on each patient group using leave-one-out cross-validation. The volume difference(VD) and Dice similarity coefficient(DSC) between the manual and auto-contoured CTV were calculated to evaluate the results. Distances from GTV-to-CTV were computed about each patient’s GTV and these distances, in addition to distances from GTV to surrounding anatomy in the expansion direction, were utilized in the regression-SVM method. The classification-SVM method used categorical voxel-information (GTV, selected anatomical structures, else) from a 3×3×3cm3 ROI centered about the voxel to classify voxels as CTV. Results: Volumes for the auto-contoured CTVs ranged from 17.1 to 149.1cc and 17.4 to 151.9cc; the average(range) VD between manual and auto-contoured CTV were 0.93 (0.48–1.59) and 1.16(0.48–1.97); while average(range) DSC values were 0.75(0.59–0.88) and 0.74(0.59–0.81) for the regression-SVM and classification-SVM methods, respectively. Conclusion: We developed two novel machine learning methods to delineate

  5. Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery.

    Science.gov (United States)

    Chittiboina, Prashant; Talagala, S Lalith; Merkle, Hellmut; Sarlls, Joelle E; Montgomery, Blake K; Piazza, Martin G; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R; Oldfield, Edward H; Koretsky, Alan P; Butman, John A

    2016-12-01

    OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing's disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra-high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm 3 and 0.15 × 0.15 × 0.30 mm 3 , respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult

  6. Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery

    Science.gov (United States)

    Chittiboina, Prashant; Talagala, S. Lalith; Merkle, Hellmut; Sarlls, Joelle E.; Montgomery, Blake K.; Piazza, Martin G.; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R.; Oldfield, Edward H.; Koretsky, Alan P.; Butman, John A.

    2016-01-01

    OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing’s disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra–high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm3 and 0.15 × 0.15 × 0.30 mm3, respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult pituitary

  7. Intensity correction method customized for multi-animal abdominal MR imaging with 3 T clinical scanner and multi-array coil

    International Nuclear Information System (INIS)

    Mitsuda, Minoru; Yamaguchi, Masayuki; Nakagami, Ryutaro; Furuta, Toshihiro; Fujii, Hirofumi; Sekine, Norio; Niitsu, Mamoru; Moriyama, Noriyuki

    2013-01-01

    Simultaneous magnetic resonance (MR) imaging of multiple small animals in a single session increases throughput of preclinical imaging experiments. Such imaging using a 3-tesla clinical scanner with multi-array coil requires correction of intensity variation caused by the inhomogeneous sensitivity profile of the coil. We explored a method for correcting intensity that we customized for multi-animal MR imaging, especially abdominal imaging. Our institutional committee for animal experimentation approved the protocol. We acquired high resolution T 1 -, T 2 -, and T 2 * -weighted images and low resolution proton density-weighted images (PDWIs) of 4 rat abdomens simultaneously using a 3T clinical scanner and custom-made multi-array coil. For comparison, we also acquired T 1 -, T 2 -, and T 2 * -weighted volume coil images in the same rats in 4 separate sessions. We used software created in-house to correct intensity variation. We applied thresholding to the PDWIs to produce binary images that displayed only a signal-producing area, calculated multi-array coil sensitivity maps by dividing low-pass filtered PDWIs by low-pass filtered binary images pixel by pixel, and divided uncorrected T 1 -, T 2 -, or T 2 * -weighted images by those maps to obtain intensity-corrected images. We compared tissue contrast among the liver, spinal canal, and muscle between intensity-corrected multi-array coil images and volume coil images. Our intensity correction method performed well for all pulse sequences studied and corrected variation in original multi-array coil images without deteriorating the throughput of animal experiments. Tissue contrasts were comparable between intensity-corrected multi-array coil images and volume coil images. Our intensity correction method customized for multi-animal abdominal MR imaging using a 3T clinical scanner and dedicated multi-array coil could facilitate image interpretation. (author)

  8. Magnetic Test Facility - Sensor and Coil Calibrations

    Science.gov (United States)

    2013-08-01

    amplitude of signals induced into the sensor. 2.1.1.2 Fluxgate magnetometers Fluxgate sensors consist of a ferromagnetic core, around which drive and sense...kHz range to be measured. Fluxgate magnetometers do not have a lower limit to their fre- quency response, and hence can be used to measure...placed within a larger triaxial coil which is used in conjunction with a fluxgate magnetometer to cancel earth’s field at the cen- tre of the coil. A

  9. Magnetic resonance dacryocystography: comparison between conventional surface coils and microscopic coils

    International Nuclear Information System (INIS)

    Abreu Junior, Luiz de; Wolosker, Angela Maria Borri; Borri, Maria Lucia; Galvao Filho, Mario de Melo; Hartmann, Luiz Guilherme de Carvalho; D'Ippolito, Giuseppe; Castro, Claudio Campi de

    2008-01-01

    Objective: Magnetic resonance imaging has been utilized in the evaluation of the lacrimal apparatus with some advantages over conventional dacryocystography. The present study was aimed at acquiring high resolution images utilizing microscopic coils for evaluating typical structures of the lacrimal apparatus as compared with the findings observed with conventional surface coils. Materials and methods: Five asymptomatic volunteers with no history of epiphora were submitted to high-field magnetic resonance imaging with microscopic and conventional surface coils, and STIR sequence after instillation of saline solution. The definition of normal anatomic structures of lacrimal apparatuses was compared utilizing conventional and microscopic surface coils. Based on a consensual scoring system, the mean values for each structure were calculated by two observers. Results: In 90% of cases, higher scores were attributed to images acquired with the microscopic coil. On average, a 1.17 point increase was observed in the scoring of anatomic structures imaged with the microscopic coil. Additionally, a subjective improvement was observed in the signal-to-noise ratio with the microscopic coil. Conclusion: Magnetic resonance dacryocystography with microscopic coils is the appropriate method for evaluating the lacrimal apparatus, providing images with better quality as compared with those acquired with conventional surface coils. (author)

  10. An analysis of 3D solvation structure in biomolecules: application to coiled coil serine and bacteriorhodopsin.

    Science.gov (United States)

    Hirano, Kenji; Yokogawa, Daisuke; Sato, Hirofumi; Sakaki, Shigeyoshi

    2010-06-17

    Three-dimensional (3D) solvation structure around coiled coil serine (Coil-Ser) and inner 3D hydration structure in bacteriorhodopsin (bR) were studied using a recently developed method named multicenter molecular Ornstein-Zernike equation (MC-MOZ) theory. In addition, a procedure for analyzing the 3D solvent distribution was proposed. The method enables us to calculate the coordination number of solvent water as well as the strength of hydrogen bonding between the water molecule and the protein. The results for Coil-Ser and bR showed very good agreement with the experimental observations.

  11. Thomson's Jumping Ring over a Long Coil

    Science.gov (United States)

    Jeffery, Rondo N.; Amiri, Farhang

    2018-01-01

    The classic jumping ring apparatus consists of a coil with an iron core that extends out of the coil. A copper or aluminum ring placed over the iron core jumps upward when AC power is applied to the coil. In this paper we will examine a modified design of the jumping ring apparatus, called the "long-coil design." It allows the ring to…

  12. COMPASS magnetic field coils and structure systems

    International Nuclear Information System (INIS)

    Crossland, R.T.; Booth, J.A.; Hayward, R.J.; Keogh, P.; Pratt, A.P.

    1987-01-01

    COMPASS is a new experimental toroidal assembly of compact design and with a wide range of physics objectives. It is required to operate either as a Tokamak or as a Reversed Field Pinch with interchangeable circular and dee-section vacuum vessels. The Toroidal field is produced by 16 rectangular coils of 4 turns with tapered conductors on the inside which nest together to form a vault to resist the centering forces. The coils are designed to produce a maximum field on axis of 2.1T which requires a current of 91 kA per turn. Two central solenoids and five pairs of coils symmetrically positioned above and below the machine equator provide the poloidal field. Both coil systems are supported form a mechanical support structure which surrounds the machine. This is primarily designed to resist out-of-plane forces on the TF coils but also acts as the base support for the PF coils and vacuum vessels. An illustration of the COMPASS Load Assembly is given and shows the D-shaped vacuum vessel, the major components and the various field windings

  13. Embroidered Coils for Magnetic Resonance Sensors

    Directory of Open Access Journals (Sweden)

    Michael I. Newton

    2013-04-01

    Full Text Available Magnetic resonance imaging is a widely used technique for medical and materials imaging. Even though the objects being imaged are often irregularly shaped, suitable coils permitting the measurement of the radio-frequency signal in these systems are usually made of solid copper. One problem often encountered is how to ensure the coils are both in close proximity and conformal to the object being imaged. Whilst embroidered conductive threads have previously been used as antennae in mobile telecommunications applications, they have not previously been reported for use within magnetic resonance. In this paper we show that an embroidered single loop coil can be used in a commercial unilateral nuclear magnetic resonance system as an alternative to a solid copper. Data is presented showing the determination of both longitudinal (T1 and effective transverse (T2eff relaxation times for a flat fabric coil and the same coil conformed to an 8 cm diameter cylinder. We thereby demonstrate the principles required for the wider use of fabric based conformal coils within nuclear magnetic resonance and magnetic resonance imaging.

  14. Dual levitated coils for antihydrogen production

    Science.gov (United States)

    Wofford, J. D.; Ordonez, C. A.

    2013-04-01

    Two coaxial superconducting magnetic coils that carry currents in the same direction and that are simultaneously levitated may serve for antihydrogen plasma confinement. The configuration may be suitable for use by a collaboration at the CERN Antiproton Decelerator facility to test fundamental symmetries between the properties of hydrogen and antihydrogen. Nested Penning traps are currently used to confine recombining antihydrogen plasma. Symmetry studies require the production of sufficiently cold antihydrogen. However, plasma drifts within nested Penning traps can increase the kinetic energy of antiprotons that form antihydrogen atoms. Dual levitated coils may serve to confine relatively large, cold, dense non-drifting recombining antihydrogen plasmas. A minimum-B magnetic field that is produced by the coils could provide for atom trapping. A toroidal plasma is confined between the coils. High density plasmas may be possible, by allowing plasma pressure to balance mechanical pressure to keep the coils apart. Progress is reported on theoretical and experimental efforts. The theoretical effort includes the development of a classical trajectory Monte Carlo simulation of confinement. The experimental effort includes levitation of a NdFeB permanent ring magnet, which produces a magnetic field that is qualitatively similar to the field that would be produced by the two coaxial superconducting magnetic coils. Liquid-nitrogen-cooled Bi-2223 high-temperature-superconducting components, with a critical temperature of 108 K, were used to levitate the ring magnet. An issue concerning keeping the plane of the levitated ring horizontal is discussed.

  15. [Surface coils for magnetic-resonance images].

    Science.gov (United States)

    Rodríguez-González, Alfredo Odón; Amador-Baheza, Ricardo; Rojas-Jasso, Rafael; Barrios-Alvarez, Fernando Alejandro

    2005-01-01

    Since the introduction of magnetic resonance imaging in Mexico, the development of this important medical imaging technology has been almost non-existing in our country. The very first surface coil prototypes for clinical applications in magnetic resonance imaging has been developed at the Center of Research in Medical Imaging and Instrumentation of the Universidad Autónoma Metropolitana Iztapalapa (Metropolitan Autonomous University, Campus Iztapalapa). Two surface coil prototypes were built: a) a circular-shaped coil and b) a square-shaped coil for multiple regions of the body, such as heart, brain, knee, hands, and ankles. These coils were tested on the 1.5T imager of the ABC Hospital-Tacubaya, located in Mexico City. Brain images of healthy volunteers were obtained in different orientations: sagittal, coronal, and axial. Since images showed a good-enough clinical quality for diagnosis, it is fair to say that these coil prototypes can be used in the clinical environment, and with small modifications, they can be made compatible with almost any commercial scanner. This type of development can offer new alternatives for further collaboration between the research centers and the radiology community, in the search of new applications and developments of this imaging technique.

  16. Superior MR images with electronically tuned and decoupled surface coils

    International Nuclear Information System (INIS)

    Ingwersen, H.; Freisen, L.; Friedrich, A.; Kess, H.; Krause, N.; Meissner, R.; Popp, W.

    1987-01-01

    In order to gain free positioning of surface coils in linearly polarized transmitting coils, it is absolutely necessary to electronically decouple both coils. For circularly polarized transmitting coils, decoupling is necessary in any case. In addition to the decoupling circuit automatic electronic tuning of the surface coils is used to gain the bast ratio of signal to noise. This combination of electronically decoupling and tuning of the surface coils yields intrinsic patient safety concerning local power deposition as well as free positioning and easy handling at the same time. Block diagrams, circuit schemes, and MR images obtained with several different surface coils are shown

  17. Coil supporting device in a nuclear fusion device

    International Nuclear Information System (INIS)

    Takano, Hirohisa; Sasaki, Katsutoki.

    1976-01-01

    Object: To slide a vacuum vessel in the nuclear fusion device and a coil within the vacuum vessel and to mount the coil within the vacuum vessel in a manner that it may not be moved by an electromagnetic force, thereby preventing stress from being produced in the coil. Structure: A coil supporting plate mounted at upper and lower parts prevents damage to an insulation of the coil, said coil being held in a U-shaped groove, and can be moved integral with the coil by the action of a roller bearing with a plurality of needle-like rollers arranged in parallel. The coil supporting plate has a plurality of projections disposed on the lower surface thereof, and flat springs are placed in the projections one over another so that the spring action exerted in the lower plate causes the coil to be resiliently bias in a direction of an electromagnetic force applied thereto and to support the coil. (Yoshino, Y.)

  18. 18F-FDG PET/CT-based gross tumor volume definition for radiotherapy in head and neck Cancer: a correlation study between suitable uptake value threshold and tumor parameters

    International Nuclear Information System (INIS)

    Kao, Chia-Hung; Hsieh, Te-Chun; Yu, Chun-Yen; Yen, Kuo-Yang; Yang, Shih-Neng; Wang, Yao-Ching; Liang, Ji-An; Chien, Chun-Ru; Chen, Shang-Wen

    2010-01-01

    To define a suitable threshold setting for gross tumor volume (GTV) when using 18 Fluoro-deoxyglucose positron emission tomography and computed tomogram (PET/CT) for radiotherapy planning in head and neck cancer (HNC). Fifteen HNC patients prospectively received PET/CT simulation for their radiation treatment planning. Biological target volume (BTV) was derived from PET/CT-based GTV of the primary tumor. The BTVs were defined as the isodensity volumes when adjusting different percentage of the maximal standardized uptake value (SUVmax), excluding any artifact from surrounding normal tissues. CT-based primary GTV (C-pGTV) that had been previously defined by radiation oncologists was compared with the BTV. Suitable threshold level (sTL) could be determined when BTV value and its morphology using a certain threshold level was observed to be the best fitness of the C-pGTV. Suitable standardized uptake value (sSUV) was calculated as the sTL multiplied by the SUVmax. Our result demonstrated no single sTL or sSUV method could achieve an optimized volumetric match with the C-pGTV. The sTL was 13% to 27% (mean, 19%), whereas the sSUV was 1.64 to 3.98 (mean, 2.46). The sTL was inversely correlated with the SUVmax [sTL = -0.1004 Ln (SUVmax) + 0.4464; R 2 = 0.81]. The sSUV showed a linear correlation with the SUVmax (sSUV = 0.0842 SUVmax + 1.248; R 2 = 0.89). The sTL was not associated with the value of C-pGTVs. In PET/CT-based BTV for HNC, a suitable threshold or SUV level can be established by correlating with SUVmax rather than using a fixed threshold

  19. Head Start.

    Science.gov (United States)

    Greenman, Geri

    2000-01-01

    Discusses an art project in which students created drawings of mop heads. Explains that the approach of drawing was more important than the subject. States that the students used the chiaroscuro technique, used by Rembrandt and Caravaggio, in which light appears out of the darkness. (CMK)

  20. Versatile fill coils: initial experience as framing coils for oblong aneurysms. A technical case report.

    Science.gov (United States)

    Osanai, Toshiya; Bain, Mark; Hui, Ferdinand K

    2014-01-01

    Coil embolization of oblong aneurysms is difficult because the majority of commercially available coils are manufactured with a helical or spherical tertiary structure. While adopting framing strategies for oblong aneurysms (aspect ratio ≥ 2: 1), traditional coils may be undersized in the long axis but oversized in the short axis, resulting in increased aneurysmal wall stress, risk of re-rupture, and difficulty creating a basket that respects the aneurysmal neck. We review three cases in which versatile filling coils (VFCs) were used as the initial coils for embolization of oblong aneurysms and report coil distribution characteristics and clinical outcomes. Packing density after VFC implantation was assessed using the software AngioSuite-Neuro edition and AngioCalc. a 58-year-old woman experienced a subarachnoid hemorrhage from a ruptured anterior communicating artery aneurysm (7.5 mm × 3.5 mm). A 3-6 mm × 15 cm VFC was selected as the first coil because the flexibility of its wave-loop structure facilitates framing of an irregularly shaped aneurysm. The loop portions of the structures tend to be pressed to the extremes of the aneurysmal sac by the wave component. The VFC was introduced smoothly into the aneurysmal sac without catheter kickback. We were then able to insert detachable filling coils without any adjunctive technique and achieved complete occlusion. Complete occlusion without severe complications was achieved in all three cases in our study. Average packing density after the first coil was 15.63%. VFC coils may have a specific role in framing oblong aneurysms given their complex loop-wave design, allowing spacing of the coils at the dome and neck while keeping sac stress to a minimum.

  1. Surgical management of an ACM aneurysm eight years after coiling.

    Science.gov (United States)

    Pogády, P; Fellner, F; Trenkler, J; Wurm, G

    2007-04-01

    The authors present a case report on rebleeding of a medial cerebral aneurysm (MCA) eight years after complete endovascular coiling. The primarily successfully coiled MCA aneurysm showed a local regrowth which, however, was not the source of the rebleeding. The angiogram demonstrated no evidence of contrast filling of the coiled segment, but according to intraoperative findings (haematoma location, displacement of coils, evident place of rupture) there is no doubt that the coiled segment of the aneurysm was responsible for the haemorrhage.

  2. Three-axis orthogonal transceiver coil for eddy current sounding

    Science.gov (United States)

    Sukhanov, D.; Zavyalova, K.; Goncharik, M.

    2017-08-01

    We propose the new structure of three-axis transceiver magnetic-induction coil for eddy current probing. Due to the orientation of the coils, the direct signal from the transmitting coil to the receiving coil is minimized, which provided a high dynamic range. Sensitivity in all directions is provided by combining coils of different orientations. Numerical simulation and experimental studies of such a system have been carried out and confirmed the applicability of the proposed method and the mathematical model.

  3. A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments.

    Science.gov (United States)

    Khachaturian, Mark Haig

    2010-01-01

    Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).

  4. Clinical Validation of Atlas-Based Auto-Segmentation of Multiple Target Volumes and Normal Tissue (Swallowing/Mastication) Structures in the Head and Neck

    International Nuclear Information System (INIS)

    Teguh, David N.; Levendag, Peter C.; Voet, Peter W.J.; Al-Mamgani, Abrahim; Han Xiao; Wolf, Theresa K.; Hibbard, Lyndon S.; Nowak, Peter; Akhiat, Hafid; Dirkx, Maarten L.P.; Heijmen, Ben J.M.; Hoogeman, Mischa S.

    2011-01-01

    Purpose: To validate and clinically evaluate autocontouring using atlas-based autosegmentation (ABAS) of computed tomography images. Methods and Materials: The data from 10 head-and-neck patients were selected as input for ABAS, and neck levels I-V and 20 organs at risk were manually contoured according to published guidelines. The total contouring times were recorded. Two different ABAS strategies, multiple and single subject, were evaluated, and the similarity of the autocontours with the atlas contours was assessed using Dice coefficients and the mean distances, using the leave-one-out method. For 12 clinically treated patients, 5 experienced observers edited the autosegmented contours. The editing times were recorded. The Dice coefficients and mean distances were calculated among the clinically used contours, autocontours, and edited autocontours. Finally, an expert panel scored all autocontours and the edited autocontours regarding their adequacy relative to the published atlas. Results: The time to autosegment all the structures using ABAS was 7 min/patient. No significant differences were observed in the autosegmentation accuracy for stage N0 and N+ patients. The multisubject atlas performed best, with a Dice coefficient and mean distance of 0.74 and 2 mm, 0.67 and 3 mm, 0.71 and 2 mm, 0.50 and 2 mm, and 0.78 and 2 mm for the salivary glands, neck levels, chewing muscles, swallowing muscles, and spinal cord-brainstem, respectively. The mean Dice coefficient and mean distance of the autocontours vs. the clinical contours was 0.8 and 2.4 mm for the neck levels and salivary glands, respectively. For the autocontours vs. the edited autocontours, the mean Dice coefficient and mean distance was 0.9 and 1.6 mm, respectively. The expert panel scored 100% of the autocontours as a “minor deviation, editable” or better. The expert panel scored 88% of the edited contours as good compared with 83% of the clinical contours. The total editing time was 66 min

  5. Clinical Validation of Atlas-Based Auto-Segmentation of Multiple Target Volumes and Normal Tissue (Swallowing/Mastication) Structures in the Head and Neck

    Energy Technology Data Exchange (ETDEWEB)

    Teguh, David N. [Department of Radiation Oncology, Erasmus Medical Center-Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Levendag, Peter C., E-mail: p.levendag@erasmusmc.nl [Department of Radiation Oncology, Erasmus Medical Center-Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Voet, Peter W.J.; Al-Mamgani, Abrahim [Department of Radiation Oncology, Erasmus Medical Center-Daniel den Hoed Cancer Center, Rotterdam (Netherlands); Han Xiao; Wolf, Theresa K.; Hibbard, Lyndon S. [Elekta-CMS Software, Maryland Heights, MO 63043 (United States); Nowak, Peter; Akhiat, Hafid; Dirkx, Maarten L.P.; Heijmen, Ben J.M.; Hoogeman, Mischa S. [Department of Radiation Oncology, Erasmus Medical Center-Daniel den Hoed Cancer Center, Rotterdam (Netherlands)

    2011-11-15

    Purpose: To validate and clinically evaluate autocontouring using atlas-based autosegmentation (ABAS) of computed tomography images. Methods and Materials: The data from 10 head-and-neck patients were selected as input for ABAS, and neck levels I-V and 20 organs at risk were manually contoured according to published guidelines. The total contouring times were recorded. Two different ABAS strategies, multiple and single subject, were evaluated, and the similarity of the autocontours with the atlas contours was assessed using Dice coefficients and the mean distances, using the leave-one-out method. For 12 clinically treated patients, 5 experienced observers edited the autosegmented contours. The editing times were recorded. The Dice coefficients and mean distances were calculated among the clinically used contours, autocontours, and edited autocontours. Finally, an expert panel scored all autocontours and the edited autocontours regarding their adequacy relative to the published atlas. Results: The time to autosegment all the structures using ABAS was 7 min/patient. No significant differences were observed in the autosegmentation accuracy for stage N0 and N+ patients. The multisubject atlas performed best, with a Dice coefficient and mean distance of 0.74 and 2 mm, 0.67 and 3 mm, 0.71 and 2 mm, 0.50 and 2 mm, and 0.78 and 2 mm for the salivary glands, neck levels, chewing muscles, swallowing muscles, and spinal cord-brainstem, respectively. The mean Dice coefficient and mean distance of the autocontours vs. the clinical contours was 0.8 and 2.4 mm for the neck levels and salivary glands, respectively. For the autocontours vs. the edited autocontours, the mean Dice coefficient and mean distance was 0.9 and 1.6 mm, respectively. The expert panel scored 100% of the autocontours as a 'minor deviation, editable' or better. The expert panel scored 88% of the edited contours as good compared with 83% of the clinical contours. The total editing time was 66 min

  6. A high-performance OH coil for the Los Alamos CPRF

    International Nuclear Information System (INIS)

    Weggel, C.F.; Bogart, S.L.; Dalessandro, J.A.

    1988-01-01

    A high-performance Ohmic Heating (OH) magnet has been designed for the Confinement Physics Research Facility at the Los Alamos National Laboratory. The magnet has an outside radius at its throat of 1.00 meters. At maximum current, the maximum current density is 40 amperes per square millimetre, at which point it generates 38.32 webers, single swing (or 76.6 webers, double swing), and generates a central field of 17.37 teslas. The maximum von Miess stress is 408.6 MPa (59.26 ksi). The magnet stores 637 megajoules, with a time constant of 8.30 seconds. The magnet consists of two zones: a central hour-glass-shaped coil, and an outer coil gallery of trimming coils. The central stack is built of bandsawed spirals, the construction technique which was pioneered at MIT for the OH coils for Alcater A and C. the coil uses 42 spirals, each of which is sawed from a 5-cm-thick plate of either MZC, Elbrodur, SSC-155, or OFE copper, depending on the maximum ambient stress. The inner radius of every plate is 0.60 m, and the outside radius is tangent to a toroid whose major radius is 2.00 m and whose minor radius is 1.00 m. The pitch of each spiral is adjusted to minimize the field error. The outer trimming coils are built of high-conductivity aluminum (Alloy 1350). For ease of fabrication, all but the outermost pair of trimming coils lie in a single ''coil-gallery'' plane and carry the same current density, so that all can be wound from a single continuous strip. The trimming coils are positioned within this gallery to yield a field error of less than 7 gauss throughout a toroidal volume centered at R/sub T/ = 2.00 meters, and whose minor radius is r/sub p/ = 0.80 meters. The current density in the trimming coils is so low that vertical diagnostic access can be provided by boring 15-cm holes through the windings themselves

  7. Comparison of surface coil and knee coil for evaluation of the patellar cartilage by MR imaging

    International Nuclear Information System (INIS)

    Steen, M. van den; Maeseneer, M. de; Hoste, M.; Vanderdood, K.; Ridder, F. de; Osteaux, M.

    2003-01-01

    Purpose: The aim of this work was to compare the knee coil and the surface coil for the visualisation of the patellar cartilage. Materials and methods: In 28 patients (17 women, 11 men) with an average age of 40 years (range 14-76) with knee pain MR was performed. Transverse images were obtained using a fast spin echo proton density weighted sequence on a Philips Gyroscan Intera 1.5 T clinical system. Transverse images were obtained at the level of the patellar cartilage using both the surface and the knee coil. All images were evaluated by consensus of two radiologists. They evaluated a number of quality criteria on a 4-point scale. Criteria for artefacts were also graded on a 4-point scale. Results: For the visualisation of fluid there was no significant difference between the knee coil and the surface coil (P=0.021). For all other criteria regarding image quality and presence of imaging artefacts there was a significant difference between both coils (P<0.001) with the surface coil obtaining the better result. Conclusion: The use of the surface coil in the visualisation of the patellar cartilage can be recommended at knee MR

  8. Immunogenicity of coiled-coil based drug-free macromolecular therapeutics

    Czech Academy of Sciences Publication Activity Database

    Kverka, Miloslav; Hartley, J.M.; Chu, T.W.; Yang, J.; Heidchen, R.; Kopeček, J.

    2014-01-01

    Roč. 35, č. 2 (2014), s. 5886-5896 ISSN 1616-0177 R&D Projects: GA MŠk(CZ) EE2.3.30.0003 Grant - others:NIH(US) GM095606 Institutional support: RVO:61388971 Keywords : coiled-coil * enantiomers * HPMA copolymer Subject RIV: EC - Immunology

  9. Golgi coiled-coil proteins contain multiple binding sites for Rab family G proteins

    NARCIS (Netherlands)

    Sinka, Rita; Gillingham, Alison K.; Kondylis, Vangelis; Munro, Sean

    2008-01-01

    Vesicles and other carriers destined for the Golgi apparatus must be guided to the correct cisternae. Golgins, long coiled-coil proteins that localize to particular Golgi subdomains via their C termini, are candidate regulators of vesicle sorting. In this study, we report that the GRIP domain

  10. Numerical study of the influence of geometrical characteristics of a vertical helical coil on a bubbly flow

    Science.gov (United States)

    Saffari, H.; Moosavi, R.

    2014-11-01

    In this article, turbulent single-phase and two-phase (air-water) bubbly fluid flows in a vertical helical coil are analyzed by using computational fluid dynamics (CFD). The effects of the pipe diameter, coil diameter, coil pitch, Reynolds number, and void fraction on the pressure loss, friction coefficient, and flow characteristics are investigated. The Eulerian-Eulerian model is used in this work to simulate the two-phase fluid flow. Three-dimensional governing equations of continuity, momentum, and energy are solved by using the finite volume method. The k- ɛ turbulence model is used to calculate turbulence fluctuations. The SIMPLE algorithm is employed to solve the velocity and pressure fields. Due to the effect of a secondary force in helical pipes, the friction coefficient is found to be higher in helical pipes than in straight pipes. The friction coefficient increases with an increase in the curvature, pipe diameter, and coil pitch and decreases with an increase in the coil diameter and void fraction. The close correlation between the numerical results obtained in this study and the numerical and empirical results of other researchers confirm the accuracy of the applied method. For void fractions up to 0.1, the numerical results indicate that the friction coefficient increases with increasing the pipe diameter and keeping the coil pitch and diameter constant and decreases with increasing the coil diameter. Finally, with an increase in the Reynolds number, the friction coefficient decreases, while the void fraction increases.

  11. Can adaptive threshold-based metabolic tumor volume (MTV) and lean body mass corrected standard uptake value (SUL) predict prognosis in head and neck cancer patients treated with definitive radiotherapy/chemoradiotherapy?

    Science.gov (United States)

    Akagunduz, Ozlem Ozkaya; Savas, Recep; Yalman, Deniz; Kocacelebi, Kenan; Esassolak, Mustafa

    2015-11-01

    To evaluate the predictive value of adaptive threshold-based metabolic tumor volume (MTV), maximum standardized uptake value (SUVmax) and maximum lean body mass corrected SUV (SULmax) measured on pretreatment positron emission tomography and computed tomography (PET/CT) imaging in head and neck cancer patients treated with definitive radiotherapy/chemoradiotherapy. Pretreatment PET/CT of the 62 patients with locally advanced head and neck cancer who were treated consecutively between May 2010 and February 2013 were reviewed retrospectively. The maximum FDG uptake of the primary tumor was defined according to SUVmax and SULmax. Multiple threshold levels between 60% and 10% of the SUVmax and SULmax were tested with intervals of 5% to 10% in order to define the most suitable threshold value for the metabolic activity of each patient's tumor (adaptive threshold). MTV was calculated according to this value. We evaluated the relationship of mean values of MTV, SUVmax and SULmax with treatment response, local recurrence, distant metastasis and disease-related death. Receiver-operating characteristic (ROC) curve analysis was done to obtain optimal predictive cut-off values for MTV and SULmax which were found to have a predictive value. Local recurrence-free (LRFS), disease-free (DFS) and overall survival (OS) were examined according to these cut-offs. Forty six patients had complete response, 15 had partial response, and 1 had stable disease 6 weeks after the completion of treatment. Median follow-up of the entire cohort was 18 months. Of 46 complete responders 10 had local recurrence, and of 16 partial or no responders 10 had local progression. Eighteen patients died. Adaptive threshold-based MTV had significant predictive value for treatment response (p=0.011), local recurrence/progression (p=0.050), and disease-related death (p=0.024). SULmax had a predictive value for local recurrence/progression (p=0.030). ROC curves analysis revealed a cut-off value of 14.00 mL for

  12. Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

    International Nuclear Information System (INIS)

    Wang, Xiufang; Nie, Xinyi; Liang, Yilang; Lu, Falong; Yan, Zhongming; Wang, Yu

    2017-01-01

    Highlights: • We investigated a kind of system architecture with three coils which the repeater is copper coil or HTS coil. • We simulated the different repeater system and obtained the magnetic field distribution at different distance. • We used helical coil instead of pancake coil which does not use capacitors. • HTS intermediate coil has significant effect on improving the transmission efficiency and lengthening transmission distance than copper intermediate coil. - Abstract: Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

  13. Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiufang [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Physics and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Nie, Xinyi [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Liang, Yilang [School of Physics and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Lu, Falong [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Yan, Zhongming, E-mail: wangxiufanghappy@163.com [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Wang, Yu [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2017-01-15

    Highlights: • We investigated a kind of system architecture with three coils which the repeater is copper coil or HTS coil. • We simulated the different repeater system and obtained the magnetic field distribution at different distance. • We used helical coil instead of pancake coil which does not use capacitors. • HTS intermediate coil has significant effect on improving the transmission efficiency and lengthening transmission distance than copper intermediate coil. - Abstract: Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

  14. Optimization of field homogeneity of Helmholtz-like coils for measuring the balance of planar gradiometers

    International Nuclear Information System (INIS)

    Nordahn, M.A.; Holst, T.; Shen, Y.Q.

    1999-01-01

    Measuring the balance of planar SQUID gradiometers using a relatively small Helmholtz-like coil system requires a careful design of the coils in order to have a high degree of field uniformity along the radial direction. The level to which planar gradiometers can be balanced will be affected by any misalignment of the gradiometer relative to the ideal central position. Therefore, the maximum degree of balancing possible is calculated numerically for the Helmholtz geometry under various perturbations, including misalignment of the gradiometer along the cylindrical and the radial axis, and angular tilting relative to the normal plane. Furthermore, if the ratio between the coil separation and coil radius is chosen to be less than unity, calculations show that the expected radial uniformity of the field can be improved considerably compared to the traditional Helmholtz geometry. The optimized coil geometry is compared to the Helmholtz geometry and is found to yield up to an order of magnitude improvement of the worst case error signal within a volume spanned by the uncertainty in the alignment. (author)

  15. HEDO-2, Magnetic Field Calculation and Plot of Air Core Coils

    International Nuclear Information System (INIS)

    Preis, H.; Martin, P.

    1979-01-01

    1 - Nature of physical problem solved: HEDO-2 allows calculation of the magnetic field, magnetic volume forces, and the self and mutual inductance coefficients of arbitrary air-core coil systems. In addition, the program is suitable for the calculation and graphic representation of field and contour lines (lines B = const). 2 - Method of solution: Approximation of the spatially distributed currents by line currents, in which the number of closed line currents per coil can be freely chosen in accordance with the calculating accuracy required. All types of calculations possible with HEDO-2 are based on the field representation of line currents. 3 - Restrictions on the complexity of the problem: (a) The coils must have rectangular winding cross sections. (b) The contour of each coil must be symmetric to at least one coordinate axis. (c) The function describing the contour and the derivative of the function must be continuous. (d) Maximum number of coils n=200; (e) Maximum number of test points p=2000; (f) Test points ought not to be located on a line conductor

  16. Small Intracranial Aneurysm Treatment Using Target (®) Ultrasoft (™) Coils.

    Science.gov (United States)

    Jindal, Gaurav; Miller, Timothy; Iyohe, Moronke; Shivashankar, Ravi; Prasad, Vikram; Gandhi, Dheeraj

    2016-06-01

    The introduction of small, soft, complex-shaped microcoils has helped facilitate the endovascular treatment of small intracranial aneurysms (IAs) over the last several years. Here, we evaluate the initial safety and efficacy of treating small IAs using only Target(®) Ultrasoft(™) coils. A retrospective review of a prospectively maintained clinical database at a single, high volume, teaching hospital was performed from September 2011 to May 2015. IAs smaller than or equal to 5.0 mm in maximal dimension treated with only Target(®) Ultrasoft(™) coils were included. A total of 50 patients with 50 intracranial aneurysms were included. Subarachnoid hemorrhage from index aneurysm rupture was the indication for treatment in 23 of 50 (46%) cases, and prior subarachnoid hemorrhage (SAH) from another aneurysm was the indication for treatment in eight of 50 (16%) cases. The complete aneurysm occlusion rate was 70% (35/50), the minimal residual aneurysm rate was 14% (7/50), and residual aneurysm rate was 16% (8/50). One intraoperative aneurysm rupture occurred. Three patients died during hospitalization from clinical sequelae of subarachnoid hemorrhage. Follow-up at a mean of 13.6 months demonstrated complete aneurysm occlusion in 75% (30/40) of cases, near complete occlusion in 15% (6/40) of cases, and residual aneurysm in 10% (4/40) of cases, all four of which were retreated. Our initial results using only Target(®) Ultrasoft(™) coils for the endovascular treatment of small intracranial aneurysms demonstrate initial excellent safety and efficacy profiles.

  17. Automated de novo phasing and model building of coiled-coil proteins.

    Science.gov (United States)

    Rämisch, Sebastian; Lizatović, Robert; André, Ingemar

    2015-03-01

    Models generated by de novo structure prediction can be very useful starting points for molecular replacement for systems where suitable structural homologues cannot be readily identified. Protein-protein complexes and de novo-designed proteins are examples of systems that can be challenging to phase. In this study, the potential of de novo models of protein complexes for use as starting points for molecular replacement is investigated. The approach is demonstrated using homomeric coiled-coil proteins, which are excellent model systems for oligomeric systems. Despite the stereotypical fold of coiled coils, initial phase estimation can be difficult and many structures have to be solved with experimental phasing. A method was developed for automatic structure determination of homomeric coiled coils from X-ray diffraction data. In a benchmark set of 24 coiled coils, ranging from dimers to pentamers with resolutions down to 2.5 Å, 22 systems were automatically solved, 11 of which had previously been solved by experimental phasing. The generated models contained 71-103% of the residues present in the deposited structures, had the correct sequence and had free R values that deviated on average by 0.01 from those of the respective reference structures. The electron-density maps were of sufficient quality that only minor manual editing was necessary to produce final structures. The method, named CCsolve, combines methods for de novo structure prediction, initial phase estimation and automated model building into one pipeline. CCsolve is robust against errors in the initial models and can readily be modified to make use of alternative crystallographic software. The results demonstrate the feasibility of de novo phasing of protein-protein complexes, an approach that could also be employed for other small systems beyond coiled coils.

  18. Effects of insulation on potted superconducting coils

    International Nuclear Information System (INIS)

    Zeller, A.F.; DeKamp, J.C.; Magsig, C.T.; Nolen, J.A.; McInturff, A.D.

    1989-01-01

    Test coils using identical wire but with either Formvar or Polyesterimid insulation were fabricated to determine the effects of insulation on training behavior. It was found that the type of insulation did not affect the training behavior. While considerable attention has been paid to epoxy formulations used for superconducting coils, little study has been devoted to the effects of the wire insulation on training behavior. If the insulation does not bind well with the epoxy, the wires will not be held securely in place, and training will be required to make the coil operate at its design limit. In fact, the coil may never reach its design current, showing considerable degredation. Conversely, if the epoxy-insulation reaction is to soften or weaken the insulation, then shorts and/or training may result. The authors have undertaken a study of the effects of the insulation on potted coils wet wound with Stycast 2850 FT epoxy. The wire was insulated with one of two insulting varnishes: Formvar (a polyvinyl formal resin) or Polyesterimid (a phenolic resin). Formvar is the standard insulation in the United States while Polyesterimid the European standard

  19. The design of the SULTAN inner coil

    International Nuclear Information System (INIS)

    Franken, W.M.P.; Spoorenberg, C.J.G.

    1981-12-01

    The background field of the first phase of the test facility SULTAN will be generated by two concentric solenoids: a 6 Tesla outer coil with a free bore of 1.3 m and an inner coil for increasing the field to 8 Tesla. The free bore (cold) will be 1.055 m. The final design of the 8 Tesla inner coil is described. The coil will operate at an overall current density of 23 x 10 6 A/m 2 . It will be cooled directly by forced flow supercritical helium. A hollow conductor is applied, composed of a rectangular copper tube and a 16 strands Rutherford cable, soldered on one side of the tube. The copper tube will be cold worked to cope with the high stress level (165 MPa). The design base (field and stress analysis, cooling, stability), the mechanical design and the instrumentation will be specified. The design and construction of the coil is a part of the collaboration between ECN and Holec Transformer Group

  20. Optimal design for MRI surface coils

    International Nuclear Information System (INIS)

    Rivera, M.; Vaquero, J.J.; Santos, A.; Pozo, F. del; Ruiz-Cabello, J.

    1997-01-01

    To demonstrate the possibility of designing and constructing specific surface coils or antennae for MRI viewing of each particular tissue producing better results than those provided by a general purpose surface coil. The study was performed by the Bioengineering and Telemedicine Group of Madrid Polytechnical University and was carried out at the Pluridisciplinary Institute of the Universidad Complutense in Madrid, using a BMT-47/40 BIOSPEC resonance unit from Bruker. Surface coils were custom-designed and constructed for each region to be studied, and optimized to make the specimen excitation field as homogeneous as possible, in addition to reducing the brightness artifact. First, images were obtained of a round, water phantom measuring 50 mm in diameter, after which images of laboratory rats and rabbits were obtained. The images thus acquired were compared with the results obtained with the coil provided by the manufacturer of the equipment, and were found to be of better quality, allowing the viewing of deeper tissue for the specimen as well as reducing the brightness artifact. The construction of surface coils for viewing specific tissues or anatomical regions improves image quality. The next step in this ongoing project will be the application of these concepts to units designed for use in humans. (Author) 14 refs

  1. Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

    Energy Technology Data Exchange (ETDEWEB)

    Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de; Lindemann, Maike E. [High Field and Hybrid MR Imaging, University Hospital Essen, Essen 45147 (Germany); Lanz, Titus [Rapid Biomedical GmbH, Rimpar 97222 (Germany); Kinner, Sonja [Institute for Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen 45147 (Germany); Quick, Harald H. [High Field and Hybrid MR Imaging, University Hospital Essen, Essen 45147, Germany and Erwin L. Hahn Institute for MR Imaging, University Duisburg-Essen, Essen 45141 (Germany)

    2016-08-15

    Purpose: This study aims to develop, implement, and evaluate a 16-channel radiofrequency (RF) coil for integrated positron emission tomography/magnetic resonance (PET/MR) imaging of breast cancer. The RF coil is designed for optimized MR imaging performance and PET transparency and attenuation correction (AC) is applied for accurate PET quantification. Methods: A 16-channel breast array RF coil was designed for integrated PET/MR hybrid imaging of breast cancer lesions. The RF coil features a lightweight rigid design and is positioned with a spacer at a defined position on the patient table of an integrated PET/MR system. Attenuation correction is performed by generating and applying a dedicated 3D CT-based template attenuation map. Reposition accuracy of the RF coil on the system patient table while using the positioning frame was tested in repeated measurements using MR-visible markers. The MR, PET, and PET/MR imaging performances were systematically evaluated using modular breast phantoms. Attenuation correction of the RF coil was evaluated with difference measurements of the active breast phantoms filled with radiotracer in the PET detector with and without the RF coil in place, serving as a standard of reference measurement. The overall PET/MR imaging performance and PET quantification accuracy of the new 16-channel RF coil and its AC were then evaluated in first clinical examinations on ten patients with local breast cancer. Results: The RF breast array coil provides excellent signal-to-noise ratio and signal homogeneity across the volume of the breast phantoms in MR imaging and visualizes small structures in the phantoms down to 0.4 mm in plane. Difference measurements with PET revealed a global loss and thus attenuation of counts by 13% (mean value across the whole phantom volume) when the RF coil is placed in the PET detector. Local attenuation ranging from 0% in the middle of the phantoms up to 24% was detected in the peripheral regions of the phantoms at

  2. Critical current studies of a HTS rectangular coil

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Z. [Department of Engineering, University of Cambridge (United Kingdom); Chudy, M., E-mail: Michal.chudy@stuba.sk [Graduate School of Technology Management, University of Pretoria (South Africa); Institute of Power and Applied Electrical Engineering, Slovak University of Technology in Bratislava (Slovakia); Ruiz, H.S. [Department of Engineering, University of Leicester, Leicester LE1 7RH (United Kingdom); Zhang, X.; Coombs, T. [Department of Engineering, University of Cambridge (United Kingdom)

    2017-05-15

    Highlights: • Unique square pancake coil was manufactured. • Measurements in relatively high magnetic field were performed. • Different sections of the coil were characterized. • Parts of the coil which are limiting critical current were identified. - Abstract: Nowadays, superconducting high field magnets are used in numerous applications due to their superior properties. High temperature superconductors (HTS) are usually used for production of circular pancake or racetrack coils. However different geometries of HTS coils might be required for some specific applications. In this study, the HTS coil wound on a rectangular frame was fully characterized in homogeneous DC background field. The study contains measurements of critical current angular dependencies. The critical current of the entire coil and two selected strands under different magnitudes and orientations of external magnetic fields are measured. The critical regions of the coil in different angular regimes are determined. This study brings better understanding of the in- field performance of HTS coils wound on frames with right-angles.

  3. Fabrication of the KSTAR toroidal field coil structure

    International Nuclear Information System (INIS)

    Choi, C.H.; Sa, J.W.; Park, H.K.; Hong, K.H.; Shin, H.; Kim, H.T.; Bak, J.S.; Lee, G.S.; Kwak, J.H.; Moon, H.G.; Yoon, H.H.; Lee, J.W.; Lee, S.K.; Song, J.Y.; Nam, K.M.; Byun, S.E.; Kim, H.C.; Ha, E.T.; Ahn, H.J.; Kim, D.S.; Lee, J.S.; Park, K.H.; Hong, C.D.

    2005-01-01

    The KSTAR toroidal field (TF) coil structure is under fabrication upon completion of engineering design and prototype construction. The prototype TF coil structure has been fabricated within allowable tolerances. Encasing of the prototype TF coil (TF00) in the prototype structure has been carried out through major processes involving a coil encasing, an enclosing weld, a vacuum pressure impregnation, and an outer surface machining. During the enclosing weld of the TF00 coil structure, we have measured temperatures and stresses on the coil surface. Assembly test had been performed with the TF00 coil structure. We have chosen Type 316LN as material of the TF coil structure. We used the narrow-gap TIG welding method. Doosan Heavy Industries and Construction Company (DHI) will complete the fabrication of the TF coil structure in Feb. 2006. (author)

  4. CS model coil experimental log book

    Energy Technology Data Exchange (ETDEWEB)

    Nishijima, Gen; Sugimoto, Makoto; Nunoya, Yoshihiko; Wakabayashi, Hiroshi; Tsuji, Hiroshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2001-02-01

    Charging test of the ITER CS Model Coil which is the world's largest superconducting pulse coil and the CS Insert Coil had started at April 11, 2000 and had completed at August 18, 2000. In the campaign, total shot numbers were 356 and the size of the data file in the DAS (Data Acquisition System) was over 20 GB. This report is a database that consists of the log list and the log sheets of every shot. One can access the database, make a search, and browse results via Internet (http://1ogwww.naka.jaeri.go.jp). The database will be useful to quick search to choose necessary shots. (author)

  5. OCLATOR (One Coil Low Aspect Toroidal Reactor)

    International Nuclear Information System (INIS)

    Yoshikawa, S.

    1980-02-01

    A new approach to construct a tokamak-type reactor(s) is presented. Basically the return conductors of toroidal field coils are eliminated and the toroidal field coil is replaced by one single large coil, around which there will be placed several tokamaks or other toroidal devices. The elimination of return conductors should, in addition to other advantages, improve the accessibility and maintainability of the tokamaks and offer a possible alternative to the search for special materials to withstand large neutron wall loading, as the frequency of changeover would be increased due to minimum downtime. It also makes it possible to have a low aspect ratio tokamak which should improve the β limit, so that a low toroidal magnetic field strength might be acceptable, meaning that the NbTi superconducting wire could be used. This system is named OCLATOR

  6. MFTF test coil construction and performance

    International Nuclear Information System (INIS)

    Cornish, D.N.; Zbasnik, J.P.; Leber, R.L.; Hirzel, D.G.; Johnston, J.E.; Rosdahl, A.R.

    1978-01-01

    A solenoid coil, 105 cm inside the 167 cm outside diameter, has been constructed and tested to study the performance of the stabilized Nb--Ti conductor to be used in the Mirror Fusion Test Facility (MFTF) being built at Lawrence Livermore Laboratory. The insulation system of the test coil is identical to that envisioned for MFTF. Cold-weld joints were made in the conductor at the start and finish of each layer; heaters were fitted to some of these joints and also to the conductor at various locations in the winding. This paper gives details of the construction of the coil and the results of the tests carried out to determine its propagation and recovery characteristics

  7. Considerations against a force compensated coil

    International Nuclear Information System (INIS)

    Hassenzahl, W.

    1988-08-01

    The cost of structural components in a large superconducting coil may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the sources balance and reduce the total structural requirement is oft proposed. A suitable geometry has never been found for the fundamental reason that there can be no force compensated solution. In this paper, the general problem is presented and an analysis of the energy stored and stresses produced in the structure are described in a fundamental way. Finally, the relation between structural mass M and stored energy E, M ≥/rho/E/σ/sub w/, that is valid for all magnetic systems is developed, where /rho/ is the density of the structure and σ/sub w/ is the working stress in the structure. 12 refs., 2 figs

  8. Considerations against a force compensated coil

    International Nuclear Information System (INIS)

    Hassenzahl, W.

    1988-08-01

    The cost of structural components in a large superconducting coil may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the forces balance and reduce the total structural requirement is oft proposed. A suitable geometry has never been found for the fundamental reason that there can be no force compensated solution. In this paper, the general problem is presented and an analysis of the energy stored and stresses produced in the structure are described in a fundamental way. Finally, the relation between structural mass M and stored energy E, M ≥ /rho/E/σ/sub w/, that is valid for all magnetic systems is developed, where /rho/ is the density of the structure and σ/sub w/ is the working stress in the structure. 8 refs., 2 figs

  9. Acoustic rainbow trapping by coiling up space

    KAUST Repository

    Ni, Xu

    2014-11-13

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea.

  10. Isabelle dipole and quadrupole coil configurations

    International Nuclear Information System (INIS)

    Dahl, P.F.; Hahn, H.

    1980-01-01

    The coil configurations of the ISABELLE dipole and quadrupole magnets have been reviewed and a number of improvements were suggested for incorporation into the final design. The coil designs are basically single layer multiple block approximations to cosine current distributions, wound from a high aspect ratio non-keystoned braided conductor. The blocks are separated by knife-edge wedges to maximize the quench propagation velocity. The current density variation is obtained by an appropriate distribution of the spacer turns and, to a lesser degree, by the wedge locations. The use of inert turns is necessary to minimize the peak field enhancement both in the ends and in the two dimensional section. Schemes for deriving turns distributions yielding harmonic coefficients satisfying the stringent ISABELLE tolerances on field uniformity, while allowing for simplicity in winding and taking into account quench propagation considerations, will be discussed, as well as our approach to the coil end configuration

  11. FRC translation into a compression coil

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1985-01-01

    Several features of the problem of FRC translation into a compression coil are considered. First, the magnitude of the guide field is calculated and found to exceed that which would be applied to a flux conserver. Second, energy conservation is applied to FRC translation from a flux conserver into a compression coil. It is found that a significant temperature decrease is required for translation to be energetically possible. The temperature change depends on the external inductance in the compression circuit. An analogous case is that of a compression region composed of a compound magnet; in this case the temperature change depends on the ratio of inner and outer coil radii. Finally, the kinematics of intermediate translation states are calculated using an ''abrupt transition'' model. It is found, in this model, that the FRC must overcome a potential hill during translation, which requires a small initial velocity

  12. Acoustic rainbow trapping by coiling up space

    KAUST Repository

    Ni, Xu; Wu, Ying; Chen, Ze-Guo; Zheng, Li-Yang; Xu, Ye-Long; Nayar, Priyanka; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

    2014-01-01

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea.

  13. Postoperative volume balance

    DEFF Research Database (Denmark)

    Frost, H; Mortensen, C.R.; Secher, Niels H.

    2017-01-01

    In healthy humans, stroke volume (SV) and cardiac output (CO) do not increase with expansion of the central blood volume by head-down tilt or administration of fluid. Here, we exposed 85 patients to Trendelenburg's position about one hour after surgery while cardiovascular variables were determin...

  14. Dryout occurrence in a helically coiled steam generator for nuclear power application

    Directory of Open Access Journals (Sweden)

    Santini L.

    2014-03-01

    Full Text Available Dryout phenomena have been experimentally investigated in a helically coiled steam generator tube. The experiences carried out in the present work are part of a wide experimental program devoted to the study of a GEN III+ innovative nuclear power plant [1].The experimental facility consists in an electrically heated AISI 316L stainless steel coiled tube. The tube is 32 meters long, 12.53 mm of inner diameter, with a coil diameter of 1m and a pitch of 0.79 m, resulting in a total height of the steam generator of 8 meters. The thermo-hydraulics conditions for dryout investigations covered a spectrum of mass fluxes between 199 and 810 kg/m2s, the pressures ranges from 10.7 to 60.7 bar, heat fluxes between 43.6 to 209.3 kW/m2.Very high first qualities dryout, between 0.72 and 0.92, were found in the range of explored conditions, comparison of our results with literature available correlations shows the difficulty in predicting high qualities dryout in helical coils., immediately following the heading. The text should be set to 1.15 line spacing. The abstract should be centred across the page, indented 15 mm from the left and right page margins and justified. It should not normally exceed 200 words.

  15. High voltage investigations for ITER coils

    International Nuclear Information System (INIS)

    Fink, S.; Fietz, W.H.

    2006-01-01

    The superconducting ITER magnets will be excited with high voltage during operation and fast discharge. Because the coils are complex systems the internal voltage distribution can differ to a large extent from the ideal linear voltage distribution. In case of fast excitations internal voltages between conductor and radial plate of a TF coil can be even higher than the terminal voltage of 3.5 kV to ground which appears during a fast discharge without a fault. Hence the determination of the transient voltage distribution is important for a proper insulation co-ordination and will provide a necessary basis for the verification of the individual insulation design and the choice of test voltages and waveforms. Especially the extent of internal overvoltages in case of failures, e. g. malfunction of discharge units and / or arcing is of special interest. Transient calculations for the ITER TF coil system have been performed for fast discharge and fault scenarios to define test voltages for ITER TF. The conductor and radial plate insulation of the ITER TF Model Coil were exposed at room temperature to test voltages derived from the results from these calculations. Breakdown appeared during the highest AC voltage step. A fault scenario for the TF fast discharge system is presented where one fault triggers a second fault, leading to considerable voltage stress. In addition a FEM model of Poloidal Field Coil 3 for the determination of the parameters of a detailed network model is presented in order to prepare detailed investigations of the transient voltage behaviour of the PF coils. (author)

  16. Can an "Aesthetic" Intervention (Braided Hair Coil) Cause Hair Loss After an Aesthetic Operation?

    Science.gov (United States)

    Dionyssopoulos, Alexander; Papaconstantinou, Antony; Stoltidou, Alexandra; Spyropoulou, Georgia-Alexandra

    2014-07-01

    Postoperative pressure alopecia (PPA), defined as hair loss caused by prolonged pressure on the patient's scalp during surgery, is an uncommon condition after aesthetic surgery. Originally, it was described for patients who underwent lengthy cardiovascular and gynecologic operations. The authors present a rare case, in which hair loss occurred after secondary breast augmentation (replacement of breast implants). The PPA appeared in the occipitoparietal region of the patient's scalp approximately 2 weeks after surgery. The operation was completed in less than 3 hours, without any fluctuations in the patient's blood pressure or any unusual blood loss. There were no other precipitating factors such as anemia or coagulopathies. The probable cause of this unexpected result was the patient's braided hair coil, which had not been noted before the operation. The patient habitually, and on the day of her operation, combed her hair into a braided coil, which placed extra pressure on the occipitoparietal region. The hair loss was temporary, and hair regrowth was complete within 2 months. This incident may have been avoided if the braided hair coil had been noted by nursing or other medical staff preoperatively. Repositioning the head every 30 minutes and providing adequate head padding during surgery are advised to protect the patient and prevent such incidents. 5. © 2014 The American Society for Aesthetic Plastic Surgery, Inc.

  17. Study of electric phenomena in energy dumping of LCT coil

    International Nuclear Information System (INIS)

    Oka, Koichi; Tsuji, Hiroshi; Nishi, Masataka; Shimamoto, Susumu

    1980-03-01

    In IEA-LCT coil, electric phenomena in energy dumping were studied analytically and experimentally. Protection resistance of the Japanese LCT coil is chosen as 0.1 Ω considering the quenching voltage, so that temperature rise of the coil is no problem. Energy dumping characteristic of the six-coil system is calculated under different conditions. It is concluded that simultaneous dumping of all the coils with the equivalent resistance values of protection is necessary. Flashover voltage tests of the model in 4.2 K liquid helium, 4.2 K gas helium and 4.2 K boiling helium show margin in practical quenching voltage of the coil. (author)

  18. Resistive demountable toroidal-field coils for tokamak reactors

    International Nuclear Information System (INIS)

    Jassby, D.L.; Jacobsen, R.A.; Kalnavarns, J.; Masson, L.S.; Sekot, J.P.

    1981-07-01

    Readily demountable TF (toroidal-field) coils allow complete access to the internal components of a tokamak reactor for maintenance of replacement. The requirement of readily demountable joints dictates the use of water-cooled resistive coils, which have a host of decisive advantages over superconducting coils. Previous papers have shown that resistive TF coils for tokamak reactors can operate in the steady state with acceptable power dissipation (typically, 175 to 300 MW). This paper summarizes results of parametric studies of size optimization of rectangular TF coils and of a finite-element stress analysis, and examines several candidate methods of implementing demountable joints for rectangular coils constructed of plate segments

  19. Stress distributions of coils for toroidal magnetic field

    International Nuclear Information System (INIS)

    Kajita, Tateo; Miyamoto, Kenro.

    1976-01-01

    The stress distributions of a D shaped coil and a circular coil are computed by the finite element method. The dependences of the stress distribution on the geometrical parameters of the stress distribution on the geometrical parameters of the coils and supporting methods are examined. The maximum amount of the stress in the D shaped coil is not much smaller than that of the circular one. However, the stress distribution of the D shaped coil becomes much more uniform. The supporting method has as much effect as the geometrical parameters of the coil on the stress distribution. (auth.)

  20. Zero current measurements using the Rogowski coil

    International Nuclear Information System (INIS)

    Gregor, J.; Jakubova, I.; Kadlec, P.; Senk, J.; Vavra, Z.

    1997-01-01

    The zero current measurements using the Rogowski coil carried out on the model of the extinguishing chamber of hv SF 6 circuit breaker with self-flow generation are presented in the paper. The time course of the post-arc current obtained by numerical integration of the measured induced voltage of the Rogowski coil gives information not only about the value of the residual current after the successful interruption but also about the current changes connected with the dynamic behaviour of the arc during its quenching. (author)

  1. Self-assembling segmented coiled tubing

    Science.gov (United States)

    Raymond, David W.

    2016-09-27

    Self-assembling segmented coiled tubing is a concept that allows the strength of thick-wall rigid pipe, and the flexibility of thin-wall tubing, to be realized in a single design. The primary use is for a drillstring tubular, but it has potential for other applications requiring transmission of mechanical loads (forces and torques) through an initially coiled tubular. The concept uses a spring-loaded spherical `ball-and-socket` type joint to interconnect two or more short, rigid segments of pipe. Use of an optional snap ring allows the joint to be permanently made, in a `self-assembling` manner.

  2. Multiple coil closure of isolated aortopulmonary collateral

    Directory of Open Access Journals (Sweden)

    Padhi Sumanta

    2010-01-01

    Full Text Available A 7-month-old girl was diagnosed to have large aortopulmonary collateral during evaluation for congestive heart failure. There was no other evidence of cardiopulmonary disease. The collateral was successfully closed with multiple coils delivered sequentially. We describe the issues associated during closure of the aortopulmonary collateral in this case. To the best of our knowledge, this is the first reported case of large aortopulmonary collateral presenting with heart failure in an otherwise structurally normal heart that was closed successfully with multiple coils delivered sequentially.

  3. Superconducting Coil Winding Machine Control System

    Energy Technology Data Exchange (ETDEWEB)

    Nogiec, J. M. [Fermilab; Kotelnikov, S. [Fermilab; Makulski, A. [Fermilab; Walbridge, D. [Fermilab; Trombly-Freytag, K. [Fermilab

    2016-10-05

    The Spirex coil winding machine is used at Fermilab to build coils for superconducting magnets. Recently this ma-chine was equipped with a new control system, which al-lows operation from both a computer and a portable remote control unit. This control system is distributed between three layers, implemented on a PC, real-time target, and FPGA, providing respectively HMI, operational logic and direct controls. The system controls motion of all mechan-ical components and regulates the cable tension. Safety is ensured by a failsafe, redundant system.

  4. A new type of coil structure called pan-shaped coil of wireless charging system based on magnetic resonance

    Science.gov (United States)

    Yue, Z. K.; Liu, Z. Z.; Hou, Y. J.; Zeng, H.; Liang, L. H.; Cui, S.

    2017-11-01

    The problem that misalignment between the transmitting coil and the receiving coil significantly impairs the transmission power and efficiency of the system has been attached more and more attention. In order to improve the uniformity of the magnetic field between the two coils to solve this problem, a new type of coil called pan-shaped coil is proposed. Three-dimension simulation models of the planar-core coil and the pan-shaped coil are established using Ansoft Maxwell software. The coupling coefficient between the transmitting coil and the receiving coil is obtained by simulating the magnetic field with the receiving coil misalignment or not. And the maximum percentage difference strength along the radial direction which is defined as the magnetic field uniformity factor is calculated. According to the simulation results of the two kinds of coil structures, it is found that the new type of coil structure can obviously improve the uniformity of the magnetic field, coupling coefficient and power transmission properties between the transmitting coil and the receiving coil.

  5. Fine-tuning of protein domain boundary by minimizing potential coiled coil regions

    International Nuclear Information System (INIS)

    Iwaya, Naoko; Goda, Natsuko; Unzai, Satoru; Fujiwara, Kenichiro; Tanaka, Toshiki; Tomii, Kentaro; Tochio, Hidehito; Shirakawa, Masahiro; Hiroaki, Hidekazu

    2007-01-01

    Structural determination of individual protein domains isolated from multidomain proteins is a common approach in the post-genomic era. Novel and thus uncharacterized domains liberated from intact proteins often self-associate due to incorrectly defined domain boundaries. Self-association results in missing signals, poor signal dispersion and a low signal-to-noise ratio in 1 H- 15 N HSQC spectra. We have found that a putative, non-canonical coiled coil region close to a domain boundary can cause transient hydrophobic self-association and monomer-dimer equilibrium in solution. Here we propose a rational method to predict putative coiled coil regions adjacent to the globular core domain using the program COILS. Except for the amino acid sequence, no preexisting knowledge concerning the domain is required. A small number of mutant proteins with a minimized coiled coil region have been rationally designed and tested. The engineered domains exhibit decreased self-association as assessed by 1 H- 15 N HSQC spectra with improved peak dispersion and sharper cross peaks. Two successful examples of isolating novel N-terminal domains from AAA-ATPases are demonstrated. Our method is useful for the experimental determination of domain boundaries suited for structural genomics studies

  6. Fine-tuning of protein domain boundary by minimizing potential coiled coil regions.

    Science.gov (United States)

    Iwaya, Naoko; Goda, Natsuko; Unzai, Satoru; Fujiwara, Kenichiro; Tanaka, Toshiki; Tomii, Kentaro; Tochio, Hidehito; Shirakawa, Masahiro; Hiroaki, Hidekazu

    2007-01-01

    Structural determination of individual protein domains isolated from multidomain proteins is a common approach in the post-genomic era. Novel and thus uncharacterized domains liberated from intact proteins often self-associate due to incorrectly defined domain boundaries. Self-association results in missing signals, poor signal dispersion and a low signal-to-noise ratio in (1)H-(15)N HSQC spectra. We have found that a putative, non-canonical coiled coil region close to a domain boundary can cause transient hydrophobic self-association and monomer-dimer equilibrium in solution. Here we propose a rational method to predict putative coiled coil regions adjacent to the globular core domain using the program COILS. Except for the amino acid sequence, no preexisting knowledge concerning the domain is required. A small number of mutant proteins with a minimized coiled coil region have been rationally designed and tested. The engineered domains exhibit decreased self-association as assessed by (1)H-(15)N HSQC spectra with improved peak dispersion and sharper cross peaks. Two successful examples of isolating novel N-terminal domains from AAA-ATPases are demonstrated. Our method is useful for the experimental determination of domain boundaries suited for structural genomics studies.

  7. Flued head replacement alternatives

    International Nuclear Information System (INIS)

    Smetters, J.L.

    1987-01-01

    This paper discusses flued head replacement options. Section 2 discusses complete flued head replacement with a design that eliminates the inaccessible welds. Section 3 discusses alternate flued head support designs that can drastically reduce flued head installation costs. Section 4 describes partial flued head replacement designs. Finally, Section 5 discusses flued head analysis methods. (orig./GL)

  8. Four signature motifs define the first class of structurally related large coiled-coil proteins in plants.

    Directory of Open Access Journals (Sweden)

    Meier Iris

    2002-04-01

    Full Text Available Abstract Background Animal and yeast proteins containing long coiled-coil domains are involved in attaching other proteins to the large, solid-state components of the cell. One subgroup of long coiled-coil proteins are the nuclear lamins, which are involved in attaching chromatin to the nuclear envelope and have recently been implicated in inherited human diseases. In contrast to other eukaryotes, long coiled-coil proteins have been barely investigated in plants. Results We have searched the completed Arabidopsis genome and have identified a family of structurally related long coiled-coil proteins. Filament-like plant proteins (FPP were identified by sequence similarity to a tomato cDNA that encodes a coiled-coil protein which interacts with the nuclear envelope-associated protein, MAF1. The FPP family is defined by four novel unique sequence motifs and by two clusters of long coiled-coil domains separated by a non-coiled-coil linker. All family members are expressed in a variety of Arabidopsis tissues. A homolog sharing the structural features was identified in the monocot rice, indicating conservation among angiosperms. Conclusion Except for myosins, this is the first characterization of a family of long coiled-coil proteins in plants. The tomato homolog of the FPP family binds in a yeast two-hybrid assay to a nuclear envelope-associated protein. This might suggest that FPP family members function in nuclear envelope biology. Because the full Arabidopsis genome does not appear to contain genes for lamins, it is of interest to investigate other long coiled-coil proteins, which might functionally replace lamins in the plant kingdom.

  9. TPX: Contractor preliminary design review. Volume 1, Presentation and design description. Final report

    International Nuclear Information System (INIS)

    Hartman, D.; Naumovich; Walstrom, P.; Clarkson, I.; Schultheiss, J.; Burger, A.

    1995-01-01

    This first volume of the five volume set begins with a CPDR overview and then details the PF magnet system, manufacturing R ampersand D, Westinghouse R ampersand D, the central solenoid, the PF 5 ring coil, the PF 6/7 ring coil, quality assurance, and the system design description

  10. Goniometer head

    International Nuclear Information System (INIS)

    Dzhazairov-Kakhramanov, V.; Berger, V.D.; Kadyrzhanov, K.K.; Zarifov, R.A.

    1994-01-01

    The goniometer head is an electromechanical instrument that performs the independent transfer of a testing sample on three coordinate axes (X, Y, Z) within limits of ±8 mm and independent rotation relative of these directions. The instrument comprises a sample holder, bellows component and three electrometer drives. The sample holder rotates around the axes X and Y, and is installed on the central arm which rotates around axis Z. One characteristic of this instrument is its independence which allows its use in any camera for researches in the field of radiation physics. 2 figs

  11. Characteristics of bowl-shaped coils for transcranial magnetic stimulation

    Science.gov (United States)

    Yamamoto, Keita; Suyama, Momoko; Takiyama, Yoshihiro; Kim, Dongmin; Saitoh, Youichi; Sekino, Masaki

    2015-05-01

    Transcranial magnetic stimulation (TMS) has recently been used as a method for the treatment of neurological and psychiatric diseases. Daily TMS sessions can provide continuous therapeutic effectiveness, and the installation of TMS systems at patients' homes has been proposed. A figure-eight coil, which is normally used for TMS therapy, induces a highly localized electric field; however, it is challenging to achieve accurate coil positioning above the targeted brain area using this coil. In this paper, a bowl-shaped coil for stimulating a localized but wider area of the brain is proposed. The coil's electromagnetic characteristics were analyzed using finite element methods, and the analysis showed that the bowl-shaped coil induced electric fields in a wider area of the brain model than a figure-eight coil. The expanded distribution of the electric field led to greater robustness of the coil to the coil-positioning error. To improve the efficiency of the coil, the relationship between individual coil design parameters and the resulting coil characteristics was numerically analyzed. It was concluded that lengthening the outer spherical radius and narrowing the width of the coil were effective methods for obtaining a more effective and more uniform distribution of the electric field.

  12. Portal Vein Embolization before Right Hepatectomy: Improved Results Using n-Butyl-Cyanoacrylate Compared to Microparticles Plus Coils

    Energy Technology Data Exchange (ETDEWEB)

    Guiu, Boris, E-mail: boris.guiu@chu-dijon.fr; Bize, Pierre; Gunthern, Daniel [Centre Hospitalo-Univeristaire Vaudois, Digestive and Oncologic Imaging and Interventional Radiology Unit, Department of Radiology and Interventional Radiology (Switzerland); Demartines, Nicolas; Halkic, Nermin [Centre Hospitalo-Univeristaire Vaudois, Department of Visceral Surgery (Switzerland); Denys, Alban [Centre Hospitalo-Univeristaire Vaudois, Digestive and Oncologic Imaging and Interventional Radiology Unit, Department of Radiology and Interventional Radiology (Switzerland)

    2013-10-15

    Background: There is currently no consensus in the literature on which embolic agent induces the greatest degree of liver hypertrophy after portal vein embolization (PVE). Only experimental results in a pig model have demonstrated an advantage of n-butyl-cyanoacrylate (NBCA) over 3 other embolic materials (hydrophilic gel, small and large polyvinyl alcohol particles) for PVE. Therefore, the aim of this human study was to retrospectively compare the results of PVE using NBCA with those using spherical microparticles plus coils. Methods: A total of 34 patients underwent PVE using either NBCA (n = 20), or spherical microparticles plus coils (n = 14). PVE was decided according to preoperative volumetry on the basis of contrast-enhanced CT. Groups were compared for age, sex, volume of the left lobe before PVE and future remnant liver ratio (FRL) (volume of the left lobe/total liver volume - tumor volume). The primary end point was the increase in left lobe volume 1 month after PVE. Secondary end points were procedure complications and biological tolerance. Results: Both groups were similar in terms of age, sex ratio, left lobe volume, and FRL before PVE. NBCA induced a greater increase in volume after PVE than did microparticles plus coils (respectively, +74 {+-} 69 % and +23 {+-} 14 %, p < 0.05). The amount of contrast medium used for the procedure was significantly larger when microparticles and coils rather than NBCA were used (respectively, 264 {+-} 43 ml and 162 {+-} 34 ml, p < 0.01). The rate of PVE complications as well as the biological tolerance was similar in both groups. Conclusion: NBCA seems more effective than spherical microparticles plus coils to induce left-lobe hypertrophy.

  13. Artificial heart for humanoid robot using coiled SMA actuators

    Science.gov (United States)

    Potnuru, Akshay; Tadesse, Yonas

    2015-03-01

    Previously, we have presented the design and characterization of artificial heart using cylindrical shape memory alloy (SMA) actuators for humanoids [1]. The robotic heart was primarily designed to pump a blood-like fluid to parts of the robot such as the face to simulate blushing or anger by the use of elastomeric substrates for the transport of fluids. It can also be used for other applications. In this paper, we present an improved design by using high strain coiled SMAs and a novel pumping mechanism that uses sequential actuation to create peristalsis-like motions, and hence pump the fluid. Various placements of actuators will be investigated with respect to the silicone elastomeric body. This new approach provides a better performance in terms of the fluid volume pumped.

  14. TEXT poloidal coil systems power supplies

    International Nuclear Information System (INIS)

    Hutchins, S.H.; Brower, D.F.

    1977-01-01

    TEXT is a convertional iron core tokamak which will have a toroidal field of 3.0 Tesla produced by room temperature copper coils and a maximum plasma current pulse of 400 kA induced by a 40 turn Ohmic Heating coil. The major radius is 100 cm and the minor radius of the plasma is 28 cm. The machine is intended for basic research in tokamak plasma physics and atomic physics and is designed primarily to provide a stable hot plasma, extremely good diagnostic access, and reliable operation. The discharge pulse length will be 300 msec and the repetition period 120 seconds. Power for the toroidal field coils and for the ohmic heating supply is provided by a 100 MVA energy storage alternator. The vertical field, horizontal field, fast positioning, and discharge cleaning power supply systems are powered from the Tokamak Laboratory power mains. The ohmic heating power system consists of an SCR controlled premagnetizing supply and commutation circuit, the main ohmic heating capacitor bank to provide plasma breakdown and current rise, and an SCR controlled power supply which sustains plasma current during the 300 ms pulse. The vertical field power system uses a small capacitor bank and an SCR controlled supply. The horizontal field has a reversible SCR controlled supply, and the fast positioning coils are powered by bipolar output transistor controlled supplies. This paper describes the loads, required wave forms, and the specifications for these power supply systems

  15. Coiling of ruptured pericallosal artery aneurysms.

    NARCIS (Netherlands)

    Menovsky, T.; Rooij, W.J.J. van; Sluzewski, M.; Wijnalda, D.

    2002-01-01

    OBJECTIVE: To assess the technical feasibility of treating ruptured pericallosal artery aneurysms with detachable coils and to evaluate the anatomic and clinical results. METHODS: Over a period of 27 months, 12 patients with a ruptured pericallosal artery aneurysm were treated with detachable

  16. Transcatheter Coil Embolization of Splenic Artery Aneurysm

    International Nuclear Information System (INIS)

    Yamamoto, Satoshi; Hirota, Shozo; Maeda, Hiroaki; Achiwa, Sachiko; Arai, Keisuke; Kobayashi, Kaoru; Nakao, Norio

    2008-01-01

    The purpose of this study was to evaluate clinical results and technical problems of transcatheter coil embolization for splenic artery aneurysm. Subjects were 16 patients (8 men, 8 women; age range, 40-80 years) who underwent transcatheter embolization for splenic artery aneurysm (14 true aneurysms, 2 false aneurysms) at one of our hospitals during the period January 1997 through July 2005. Two aneurysms (12.5%) were diagnosed at the time of rupture. Multiple splenic aneurysms were found in seven patients. Aneurysms were classified by site as proximal (or strictly ostial) (n = 3), middle (n = 3), or hilar (n = 10). The indication for transcatheter arterial embolization was a false or true aneurysm 20 mm in diameter. Embolic materials were fibered coils and interlocking detachable coils. Embolization was performed by the isolation technique, the packing technique, or both. Technically, all aneurysms were devascularized without severe complications. Embolized aneurysms were 6-40 mm in diameter (mean, 25 mm). Overall, the primary technical success rate was 88% (14 of 16 patients). In the remaining 2 patients (12.5%), partial recanalization occurred, and re-embolization was performed. The secondary technical success rate was 100%. Seven (44%) of the 16 study patients suffered partial splenic infarction. Intrasplenic branching originating from the aneurysm was observed in five patients. We conclude that transcatheter coil embolization should be the initial treatment of choice for splenic artery aneurysm

  17. Stellarator Coil Design and Plasma Sensitivity

    International Nuclear Information System (INIS)

    Ku, Long-Poe; Boozer, Allen H.

    2010-01-01

    The rich information contained in the plasma response to external magnetic perturbations can be used to help design stellarator coils more effectively. We demonstrate the feasibility by first devel oping a simple, direct method to study perturbations in stellarators that do not break stellarator symmetry and periodicity. The method applies a small perturbation to the plasma boundary and evaluates the resulting perturbed free-boundary equilibrium to build up a sensitivity matrix for the important physics attributes of the underlying configuration. Using this sensitivity information, design methods for better stellarator coils are then developed. The procedure and a proof-of-principle application are given that (1) determine the spatial distributions of external normal magnetic field at the location of the unperturbed plasma boundary to which the plasma properties are most sen- sitive, (2) determine the distributions of external normal magnetic field that can be produced most efficiently by distant coils, (3) choose the ratios of the magnitudes of the the efficiently produced magnetic distributions so the sensitive plasma properties can be controlled. Using these methods, sets of modular coils are found for the National Compact Stellarator Experiment (NCSX) that are either smoother or can be located much farther from the plasma boundary than those of the present design.

  18. High-field superconducting nested coil magnet

    Science.gov (United States)

    Laverick, C.; Lobell, G. M.

    1970-01-01

    Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

  19. Coil in bottom part of splitter magnet

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    Radiation-resistant coil being bedded into the bottom part of a splitter magnet. This very particular magnet split the beam into 3 branches, for 3 target stations in the West-Area. See Annual Report 1975, p.176, Figs.14 and 15.

  20. FRC translation into a compression coil

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1986-01-01

    The equilibrium and translational kinematics of Field-Reversed Configurations (FRCs) in a cylindrical coil which does not conserve flux are problems that arise in connection with adiabatic compressional heating. In this paper, they consider several features of the problem of FRC translation into a compression coil. First, the magnitude of the guide field is calculated and found to exceed that which would be applied to a flux conserver. Second, energy conservation is applied to FRC translation from a flux conserver into a compression coil. It is found that a significant temperature decrease is required for translation to be energetically possible. The temperature change depends on the external inductance in the compression circuit. An analogous case is that of a compression region composed of a compound magnet; in this case the temperature change depends on the ratio of inner and outer coil radii. Finally, the kinematics of intermediate translation states are calculated using an abrupt transition model. It is found, in this model, that the FRC must overcome a potential hill during translation, which requires a small initial velocity

  1. Traveling-wave synchronous coil gun

    International Nuclear Information System (INIS)

    Elliott, D.G.

    1991-01-01

    This paper reports on a traveling-wave synchronous coil gun which permits independent adjustment of the magnetic field and armature current for high velocity at low armature mass fraction. Magnetic field energy is transferred from the rear of the wave to the front without passing through the power supply. Elaborate switching is required

  2. Structural design of the superconducting toroidal field coils for ITER

    International Nuclear Information System (INIS)

    Wong, F.M.G.; Sborchia, C.; Thome, R.J.; Malkov, A.; Titus, P.H.

    1995-01-01

    Structural design issues and features of the superconducting toroidal field (TF) coils for the International Thermonuclear Experimental Reactor (ITER) will be discussed. Selected analyses of the structural and mechanical behavior of the ITER TF coils will also be presented. (orig.)

  3. Hybrid equilibrium field coils for the ORNL TNS

    International Nuclear Information System (INIS)

    Peng, Y.K.M.; Strickler, D.J; Dory, R.A.

    1977-01-01

    In this study, we make a comparative study of the power supplies required by interior and exterior [to the toroidal field (TF) coils] equilibrium field coils that are separately appropriate for high-β, D-shaped plasmas in TNS. It is shown that the interior coils need power supplies that are an order of magnitude below those required by the exterior coils (while the latter case is much less difficult to build than the former). A hybrid EF coil concept is proposed that combines the interior and the exterior coils to retain their advantages in avoiding large interior coils while lowering the power supplied to the exterior coils by an order of magnitude

  4. Testing of the European LCT coil in the TOSKA facility

    International Nuclear Information System (INIS)

    Herz, W.; Katheder, H.; Krauth, H.

    1985-01-01

    The EURATOM-LCT coil was tested as a single coil in TOSKA. Load cells were mounted in the support structure to monitor forces between coil and vacuum vessel during cooldown and coil charging. Disturbances of components by magnetic fringing fields were carefully considered. To investigate the mechanical behaviour and compare it with FEM-calculations the coil was equipped with strain gauge rosettes and displacement transducers. Van Mises stresses in the coil case are in agreement with calculations. As known from special investigations during coil manufacturing the average radial Young modulus varies along the periphery caused by the different curvatures. This leads to differences with FEM-calculation (larger gaps between winding and coil case) assuming a larger constant Young modulus performed at the beginning of the project

  5. A history of detachable coils: 1987-2012.

    Science.gov (United States)

    Hui, Ferdinand K; Fiorella, David; Masaryk, Thomas J; Rasmussen, Peter A; Dion, Jacques E

    2014-03-01

    The development of detachable coils is one of the most pivotal developments in neurointervention, providing a tool that could be used to treat a wide variety of hemorrhagic stroke. From the original Guglielmi detachable coil, a number of different coil designs and delivery designs have evolved. This article reviews the history of commercially available detachable coils. A timeline of detachable coils was constructed and coil design philosophies were reviewed. A complete list of commercially available coils is presented in a timeline format. Detachable coil technology continues to evolve. Advances in construction and design have yielded products which may benefit patients in terms of safety, radiation dose reduction and cost of treatment. Continued evolution is expected, irrespective of competing disruptive technologies.

  6. Superconducting coil design for a tokamak experimental power reactor

    International Nuclear Information System (INIS)

    Turner, L.R.; Wang, S.T.; Smelser, P.

    1977-01-01

    Superconducting toroidal field (TF) and polodial-field (PF) coils have been designed for the proposed Argonne National Laboratory experimental power reactor (EPR). Features of the design include: (1) Peak field of 8 T at 4.2 K or 10 T at 3.0 K. (2) Constant-tension shape for the TF coils, corrected for the finite number (16) of coils. (3) Analysis of errors in coil alignment. (4) Comparison of safety aspects of series-connected and parallel-connected coils. (5) A 60 kA sheet conductor of NbTi with copper stabilizer and stainless steel for support. (6) Superconducting PF coils outside the TF coils. (7) The TF coils shielded from pulsed fields by high-purity aluminum

  7. Mechanical design of a high field common coil magnet

    CERN Document Server

    Caspi, S; Dietderich, D R; Gourlay, S A; Gupta, R; McInturff, A; Millos, G; Scanlan, R M

    1999-01-01

    A common coil design for high field 2-in-1 accelerator magnets has been previously presented as a "conductor-friendly" option for high field magnets applicable for a Very Large Hadron Collider. This paper presents the mechanical design for a 14 tesla 2-in-1 dipole based on the common coil design approach. The magnet will use a high current density Nb/sub 3/Sn conductor. The design addresses mechanical issues particular to the common coil geometry: horizontal support against coil edges, vertical preload on coil faces, end loading and support, and coil stresses and strains. The magnet is the second in a series of racetrack coil magnets that will provide experimental verification of the common coil design approach. (9 refs).

  8. Testing electrical insulation of LCT coils and instrumentation

    International Nuclear Information System (INIS)

    Luton, J.N.; Ulbricht, A.R.; Ellis, J.F.; Shen, S.S.; Wilson, C.T.; Okuno, K.; Siewerdt, L.O.; Zahn, G.R.; Zichy, J.A.

    1986-09-01

    Three of the superconducting test coils in the Large Coil Task (LCT) use conductors cooled internally by forced flow of helium. In the other three coils, the conductors are cooled externally by a bath of helium. The coils and facility are designed for rapid discharges (dumps) at voltages up to 2.5 kV, depending on coil design. Many coil sensors are connected electrically to the conductors. These sensor leads and signal conditioning equipment also experience high voltage. High-potential tests of ground insulation were performed on all components of the International Fusion Superconducting Magnet Test Facility (IFSMTF). Coil insulation was also tested by ring-down tests that produced voltage distributions within the coils like those occurring during rapid discharge. Methods were developed to localize problem areas and to eliminate them. The effect on breakdown voltage near the Paschen minimum of magnetic fields up to 2 T was investigated

  9. High-resolution MR imaging of triangular fibrocartilage complex (TFCC): comparison of microscopy coils and a conventional small surface coil

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Hiroshi [Department of Radiology, University of Tsukuba, Tsukuba (Japan); Department of Radiology, Brigham and Women' s Hospital, 75 Francis Street, 02115, Boston, MA (United States); Ueno, Teruko; Itai, Yuji [Department of Radiology, University of Tsukuba, Tsukuba (Japan); Tanaka, Toshikazu [Department of Orthopedic Surgery, Tsukuba Kinen Hospital, Tsukuba (Japan); Shindo, Masashi [Tsukuba University Hospital, Tsukuba (Japan)

    2003-10-01

    To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively. Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 mm in diameter), a 47-mm microscopy surface coil and a 23-mm microscopy surface coil at 1.5 T. Qualitative image analysis of MR images with three coils was performed by two radiologists who assigned one of five numerical scores (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) for five TFCC components, which were disc proper, triangular ligament, meniscus homologue, ulnotriquetral and ulnolunate ligament. Quantitative analysis included the signal-to-noise ratio (S/N) of the disc proper of TFCC, the lunate cartilage, the lunate bone and the contrast-noise-ratio (C/N) between articular cartilage and disc proper or bone marrow were measured. All structures show higher scores qualitatively on MR with microscopy coils than those with a C4 coil, and the difference was significant with the exception of the ulnolunate ligament. MR with microscopy coils showed significantly higher S/N values than those with a conventional surface coil (P<0.05 to P<0.001). T2*-weighted images using microscopy coils showed significantly higher cartilage-disc proper C/N and cartilage-bone marrow C/N (P<0.01 to P<0.001). On proton density-weighted images, the C/N between cartilage and disc proper with two microscopy coils was significantly higher (P<0.01) than that with a conventional coil. High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions. (orig.)

  10. GBNV encoded movement protein (NSm) remodels ER network via C-terminal coiled coil domain

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Pratibha; Savithri, H.S., E-mail: bchss@biochem.iisc.ernet.in

    2015-08-15

    Plant viruses exploit the host machinery for targeting the viral genome–movement protein complex to plasmodesmata (PD). The mechanism by which the non-structural protein m (NSm) of Groundnut bud necrosis virus (GBNV) is targeted to PD was investigated using Agrobacterium mediated transient expression of NSm and its fusion proteins in Nicotiana benthamiana. GFP:NSm formed punctuate structures that colocalized with mCherry:plasmodesmata localized protein 1a (PDLP 1a) confirming that GBNV NSm localizes to PD. Unlike in other movement proteins, the C-terminal coiled coil domain of GBNV NSm was shown to be involved in the localization of NSm to PD, as deletion of this domain resulted in the cytoplasmic localization of NSm. Treatment with Brefeldin A demonstrated the role of ER in targeting GFP NSm to PD. Furthermore, mCherry:NSm co-localized with ER–GFP (endoplasmic reticulum targeting peptide (HDEL peptide fused with GFP). Co-expression of NSm with ER–GFP showed that the ER-network was transformed into vesicles indicating that NSm interacts with ER and remodels it. Mutations in the conserved hydrophobic region of NSm (residues 130–138) did not abolish the formation of vesicles. Additionally, the conserved prolines at positions 140 and 142 were found to be essential for targeting the vesicles to the cell membrane. Further, systematic deletion of amino acid residues from N- and C-terminus demonstrated that N-terminal 203 amino acids are dispensable for the vesicle formation. On the other hand, the C-terminal coiled coil domain when expressed alone could also form vesicles. These results suggest that GBNV NSm remodels the ER network by forming vesicles via its interaction through the C-terminal coiled coil domain. Interestingly, NSm interacts with NP in vitro and coexpression of these two proteins in planta resulted in the relocalization of NP to PD and this relocalization was abolished when the N-terminal unfolded region of NSm was deleted. Thus, the NSm

  11. Superconductive magnet having shim coils and quench protection circuits

    International Nuclear Information System (INIS)

    Schwall, R.E.

    1987-01-01

    A superconductive magnet is described comprising: a first persistent current loop comprising a first superconductor and a main coil connected to the first superconductor, the main coil being operative in response to superconduction therein to generate a primary magnetic field; a second persistent current loop comprising a second superconductor and a shim coil connected thereto, the shim coil being operative in response to superconduction therein to generate a corrective field for correcting aberrations in a predetermined gradient in the primary magnetic field, the shim coil having fewer turns than the main coil and being inductively coupled therewith whereby small changes in the current in the main coil cause much greater changes in the current in the shim coil. The magnet is characterized by an improvement which consists of: a first heater connected across the second persistent loop in parallel with the shim coil, the first heater being normally inoperative to carry current while the shim coil and the second superconductor are superconducting, the first heater being operative in response to current therein to heat the shim coil to a resistive state; and protective circuit means comprising a second heater connected to the main coil for carrying current from the main coil upon quenching of the main coil, the second heater being disposed in thermal contact with the second superconductor to heat the second superconductor to a resistive state in response to the current from the main coil to thereby divert current in the second persistent loop through the second heater causing it to heat the shim coil to a resistive state and resistively dissipate energy therein

  12. The impact of hybrid neurosurgeons on the outcomes of endovascular coiling for unruptured cerebral aneurysms

    Science.gov (United States)

    Bekelis, Kimon; Gottlieb, Dan; Labropoulos, Nicos; Su, Yin; Tzoumakaris, Stavropoula; Jabbour, Pasqual; MacKenzie, Todd A.

    2017-01-01

    Background The impact of combined practices on the outcomes of unruptured cerebral aneurysm coiling remains an issue of debate. We investigated the association of combined open and endovascular expertise with the outcomes of unruptured cerebral aneurysm coiling. Methods We performed a cohort study of 100% of Medicare fee-for-service claims data for elderly patients who underwent endovascular coiling for unruptured cerebral aneurysms from 2007 to 2012. In order to control for confounding we used propensity score conditioning, with mixed effects to account for clustering at the HRR level. Results During the study period, there were 11,716 patients, who underwent endovascular coiling for unruptured cerebral aneurysms, and met the inclusion criteria. Of these, 1,186 (10.1%) underwent treatment by hybrid neurosurgeons, and 10,530 (89.9%) by proceduralists who performed only endovascular coiling. Multivariable regression analysis with propensity score adjustment demonstrated lack of association of combined practice with 1-year postoperative mortality (OR, 0.84; 95% CI, 0.58–1.23), discharge to rehabilitation (OR, 1.0; 95% CI, 0.66–1.51), 30-day readmission rate (OR, 1.07; 95% CI, 0.83–1.38) and length of stay (LOS) (adjusted difference, 0.41; 95% CI, −0.26 to 1.09). Higher procedural volume was independently associated with improved outcomes. Conclusions In a cohort of Medicare patients, we did not demonstrate a difference in mortality, discharge to rehabilitation, readmission rate, and LOS between hybrid neurosurgeons, and proceduralists only performing endovascular coiling. Funding Supported by grants from the National Institute on Aging (PO1- AG19783), the National Institutes of Health Common Fund (U01-AG046830), and the National Center for Advancing Translational Sciences (NCATS) of the NIH (Dartmouth Clinical and Translational Science Institute-UL1TR001086). The funders had no role in the design or execution of the study. PMID:26918479

  13. Plasmodium vivax antigen discovery based on alpha-helical coiled coil protein motif.

    Directory of Open Access Journals (Sweden)

    Nora Céspedes

    Full Text Available Protein α-helical coiled coil structures that elicit antibody responses, which block critical functions of medically important microorganisms, represent a means for vaccine development. By using bioinformatics algorithms, a total of 50 antigens with α-helical coiled coil motifs orthologous to Plasmodium falciparum were identified in the P. vivax genome. The peptides identified in silico were chemically synthesized; circular dichroism studies indicated partial or high α-helical content. Antigenicity was evaluated using human sera samples from malaria-endemic areas of Colombia and Papua New Guinea. Eight of these fragments were selected and used to assess immunogenicity in BALB/c mice. ELISA assays indicated strong reactivity of serum samples from individuals residing in malaria-endemic regions and sera of immunized mice, with the α-helical coiled coil structures. In addition, ex vivo production of IFN-γ by murine mononuclear cells confirmed the immunogenicity of these structures and the presence of T-cell epitopes in the peptide sequences. Moreover, sera of mice immunized with four of the eight antigens recognized native proteins on blood-stage P. vivax parasites, and antigenic cross-reactivity with three of the peptides was observed when reacted with both the P. falciparum orthologous fragments and whole parasites. Results here point to the α-helical coiled coil peptides as possible P. vivax malaria vaccine candidates as were observed for P. falciparum. Fragments selected here warrant further study in humans and non-human primate models to assess their protective efficacy as single components or assembled as hybrid linear epitopes.

  14. Coiled-coil forming peptides for the induction of silver nanoparticles

    International Nuclear Information System (INIS)

    Božič Abram, Sabina; Aupič, Jana; Dražić, Goran; Gradišar, Helena; Jerala, Roman

    2016-01-01

    Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at around 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.

  15. CCBuilder 2.0: Powerful and accessible coiled-coil modeling.

    Science.gov (United States)

    Wood, Christopher W; Woolfson, Derek N

    2018-01-01

    The increased availability of user-friendly and accessible computational tools for biomolecular modeling would expand the reach and application of biomolecular engineering and design. For protein modeling, one key challenge is to reduce the complexities of 3D protein folds to sets of parametric equations that nonetheless capture the salient features of these structures accurately. At present, this is possible for a subset of proteins, namely, repeat proteins. The α-helical coiled coil provides one such example, which represents ≈ 3-5% of all known protein-encoding regions of DNA. Coiled coils are bundles of α helices that can be described by a small set of structural parameters. Here we describe how this parametric description can be implemented in an easy-to-use web application, called CCBuilder 2.0, for modeling and optimizing both α-helical coiled coils and polyproline-based collagen triple helices. This has many applications from providing models to aid molecular replacement for X-ray crystallography, in silico model building and engineering of natural and designed protein assemblies, and through to the creation of completely de novo "dark matter" protein structures. CCBuilder 2.0 is available as a web-based application, the code for which is open-source and can be downloaded freely. http://coiledcoils.chm.bris.ac.uk/ccbuilder2. We have created CCBuilder 2.0, an easy to use web-based application that can model structures for a whole class of proteins, the α-helical coiled coil, which is estimated to account for 3-5% of all proteins in nature. CCBuilder 2.0 will be of use to a large number of protein scientists engaged in fundamental studies, such as protein structure determination, through to more-applied research including designing and engineering novel proteins that have potential applications in biotechnology. © 2017 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.

  16. Coiled-coil forming peptides for the induction of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Božič Abram, Sabina [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Graduate School of Biomedicine, University of Ljubljana, Ljubljana 1000 (Slovenia); Aupič, Jana [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Doctoral Programme in Chemical Sciences, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000 (Slovenia); Dražić, Goran [Laboratory for Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Gradišar, Helena [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); EN-FIST, Centre of Excellence, Trg Osvobodilne fronte 13, Ljubljana 1000 (Slovenia); Jerala, Roman, E-mail: roman.jerala@ki.si [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); EN-FIST, Centre of Excellence, Trg Osvobodilne fronte 13, Ljubljana 1000 (Slovenia)

    2016-04-08

    Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at around 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.

  17. Coiled coil peptides as universal linkers for the attachment of recombinant proteins to polymer therapeutics

    Czech Academy of Sciences Publication Activity Database

    Pechar, Michal; Pola, Robert; Laga, Richard; Ulbrich, Karel; Bednárová, Lucie; Maloň, Petr; Sieglová, Irena; Král, Vlastimil; Fábry, Milan; Vaněk, O.

    2011-01-01

    Roč. 12, č. 10 (2011), s. 3645-3655 ISSN 1525-7797 R&D Projects: GA ČR GA203/08/0543; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z40550506; CEZ:AV0Z50520514 Keywords : coiled coil * polymer the rapeutics * drug targeting Subject RIV: CC - Organic Chemistry Impact factor: 5.479, year: 2011

  18. Transport of one SC coil through the village of Meyrin

    CERN Multimedia

    1956-01-01

    The energizing coils of the Synchro-cyclotron magnet were manufactured in Belgium before travelling to Basel in Switzerland by boat and continuing by road to Geneva. The first coil reached Geneva in December 1955, with the second following in early 1956. The coils were stored in a hangar at the Geneva airport before they were brought to CERN in May 1956.

  19. Strain and stress of the ASDEX multipole magnetic coils

    International Nuclear Information System (INIS)

    Jandl, O.; Pillsticker, M.

    1978-01-01

    A brief description of the technical concept of the multipole magnetic field coils for the ASDEX tokamak is given. The various loads of the coils are explained in quality. To compute displacement and stress of the coils FEM computer programs are used. The computing models applied to this problem are founded and the results and the conclusions are reported. (orig.) [de

  20. Mechanical study of 20 MJ superconducting pulse coil

    International Nuclear Information System (INIS)

    Hattori, Yasuhide; Shimamoto, Susumu

    1985-09-01

    This paper describes calculation methods and computer codes of stress distribution in a circular-shaped superconducting pulsed coils. The stress problems of a large sized superconducting coil, for example, are discussed for 20 MJ pool-cooled pulse coil. Young's modulus of a stranded flat cable, low rigidity, is measured and evaluated. (author)

  1. Strong contributions from vertical triads to helix-partner preferences in parallel coiled coils.

    Science.gov (United States)

    Steinkruger, Jay D; Bartlett, Gail J; Woolfson, Derek N; Gellman, Samuel H

    2012-09-26

    Pairing preferences in heterodimeric coiled coils are determined by complementarities among side chains that pack against one another at the helix-helix interface. However, relationships between dimer stability and interfacial residue identity are not fully understood. In the context of the "knobs-into-holes" (KIH) packing pattern, one can identify two classes of interactions between side chains from different helices: "lateral", in which a line connecting the adjacent side chains is perpendicular to the helix axes, and "vertical", in which the connecting line is parallel to the helix axes. We have previously analyzed vertical interactions in antiparallel coiled coils and found that one type of triad constellation (a'-a-a') exerts a strong effect on pairing preferences, while the other type of triad (d'-d-d') has relatively little impact on pairing tendencies. Here, we ask whether vertical interactions (d'-a-d') influence pairing in parallel coiled-coil dimers. Our results indicate that vertical interactions can exert a substantial impact on pairing specificity, and that the influence of the d'-a-d' triad depends on the lateral a' contact within the local KIH motif. Structure-informed bioinformatic analyses of protein sequences reveal trends consistent with the thermodynamic data derived from our experimental model system in suggesting that heterotriads involving Leu and Ile are preferred over homotriads involving Leu and Ile.

  2. Historical review: another 50th anniversary--new periodicities in coiled coils.

    Science.gov (United States)

    Gruber, Markus; Lupas, Andrei N

    2003-12-01

    In 1953, Francis Crick and Linus Pauling both proposed models of supercoiled alpha helices ('coiled coils') for the structure of keratin. These were the first attempts at modelling the tertiary structure of a protein. Crick emphasized the packing mode of the side-chains ('knobs-into-holes'), which required a periodicity of seven residues over two helical turns (7/2) and a supercoil in the opposite sense of the constituent helices. By contrast, Pauling envisaged a broader set of periodicities (4/1, 7/2, 18/5, 15/4, 11/3) and supercoils of both senses. Crick's model became canonical and the 'heptad repeat' essentially synonymous with coiled coils, but 50 years later new crystal structures and protein sequences show that the less common periodicities envisaged by Pauling also occur in coiled coils, adding a variant packing mode ('knobs-to-knobs') to the standard model. Pauling's laboratory notebooks suggest that he searched unsuccessfully for this packing mode in 1953.

  3. Coiled-Coil Proteins Facilitated the Functional Expansion of the Centrosome

    Science.gov (United States)

    Kuhn, Michael; Hyman, Anthony A.; Beyer, Andreas

    2014-01-01

    Repurposing existing proteins for new cellular functions is recognized as a main mechanism of evolutionary innovation, but its role in organelle evolution is unclear. Here, we explore the mechanisms that led to the evolution of the centrosome, an ancestral eukaryotic organelle that expanded its functional repertoire through the course of evolution. We developed a refined sequence alignment technique that is more sensitive to coiled coil proteins, which are abundant in the centrosome. For proteins with high coiled-coil content, our algorithm identified 17% more reciprocal best hits than BLAST. Analyzing 108 eukaryotic genomes, we traced the evolutionary history of centrosome proteins. In order to assess how these proteins formed the centrosome and adopted new functions, we computationally emulated evolution by iteratively removing the most recently evolved proteins from the centrosomal protein interaction network. Coiled-coil proteins that first appeared in the animal–fungi ancestor act as scaffolds and recruit ancestral eukaryotic proteins such as kinases and phosphatases to the centrosome. This process created a signaling hub that is crucial for multicellular development. Our results demonstrate how ancient proteins can be co-opted to different cellular localizations, thereby becoming involved in novel functions. PMID:24901223

  4. Complete Fabrication of a Traversable 3 µm Thick NbN Film Superconducting Coil with Cu plated layer of 42m in Length in a Spiral Three-Storied Trench Engraved in a Si Wafer of 76.2 mm in Diameter Formed by MEMS Technology for a Compact SMES with High Energy Storage Volume Density

    Science.gov (United States)

    Suzuki, Yasuhiro; Iguchi, Nobuhiro; Adachi, Kazuhiro; Ichiki, Akihisa; Hioki, Tatsumi; Hsu, Che-Wei; Sato, Ryoto; Kumagai, Shinya; Sasaki, Minoru; Noh, Joo-Hyong; Sakurahara, Yuuske; Okabe, Kyohei; Takai, Osamu; Honma, Hideo; Watanabe, Hideo; Sakoda, Hitoshi; Sasagawa, Hiroaki; Doy, Hideyuki; Zhou, Shuliang; Hori, H.; Nishikawa, Shigeaki; Nozaki, Toshihiro; Sugimoto, Noriaki; Motohiro, Tomoyoshi

    2017-09-01

    Based on the concept of a novel approach to make a compact SMES unit composed of a stack of Si wafers using MEMS process proposed previously, a complete fabrication of a traversable 3 µam thick NbN film superconducting coil lined with Cu plated layer of 42m in length in a spiral three-storied trench engraved in and extended over a whole Si-wafer of 76.2 mm in diameter was attained for the first time. With decrease in temperature, the DC resistivity showed a metallic decrease indicating the current pass was in the Cu plated layer and then made a sudden fall to residual contact resistance indicating the shift of current pass from the Cu plated layer to the NbN film at the critical temperature Tc of 15.5K by superconducting transition. The temperature dependence of I-V curve showed the increase in the critical current with decrease in the temperature and the highest critical current measured was 220 mA at 4K which is five times as large as that obtained in the test fabrication as the experimental proof of concept presented in the previous report. This completion of a one wafer superconducting NbN coil is an indispensable step for the next proof of concept of fabrication of series-connected two wafer coils via superconductive joint which will read to series connected 600 wafer coils finally, and for replacement of NbN by high Tc superconductor such as YBa2Cu3O7-x for operation under the cold energy of liquid hydrogen or liquid nitrogen.

  5. Heat transfer enhancement of Al_2O_3-EG nanofluid in a car radiator with wire coil inserts

    International Nuclear Information System (INIS)

    Goudarzi, K.; Jamali, H.

    2017-01-01

    Highlights: • The purpose of this paper is heat transfer enhancement in a car radiator. • The simultaneous impacts of nanofluid EG/Al_2O_3 with wire coil inserts are studied. • Results show that the thermal performance enhancement up to 14%. • With increasing speed of cooling fan, Nusselt number at Reynolds numbers increased. - Abstract: In this experimental study, Aluminums Oxide (Al_2O_3) in Ethylene Glycol (EG) as nanofluid was used for heat transfer enhancement in car radiator together with wire coil inserts. Two wire coils inserts with different geometry and nanofluids with volume concentrations of 0.08%, 0.5% and 1% were investigated. The results indicated that the use of coils inserts enhanced heat transfer rates up to 9%. In addition, the simultaneous use of the coils inserts with the nanofluid with concentration of 0.08%, 0.5% and 1% resulted the thermal performance enhancement up to 5% as compared to the use of coils inserts alone.

  6. Design of a Nested Eight-Channel Sodium and Four-Channel Proton Coil for 7 Tesla Knee Imaging

    Science.gov (United States)

    Brown, Ryan; Madelin, Guillaume; Lattanzi, Riccardo; Chang, Gregory; Regatte, Ravinder R.; Sodickson, Daniel K.; Wiggins, Graham C.

    2012-01-01

    The critical design aim for a dual-tuned sodium/proton coil is to maximize sodium sensitivity and transmit field (B1+) homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils utilize lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio (SNR) over a volume coil. A detunable sodium birdcage was added for homogeneous sodium excitation and a four-channel proton transmit-receive array was added to provide anatomical reference imaging and B0 shimming capability. Both modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium SNR was 1.2 to 1.7 times greater in the developed eight-channel array than in a mono-nuclear sodium birdcage coil, while the developed four-channel proton array provided SNR similar to that of a commercial mono-nuclear proton birdcage coil. PMID:22887123

  7. Production of a magnetic field of 1 600 000 At/m in a non-magnetic region of volume 0.5 cubic decimeters by a coil cooled by liquid hydrogen (1963); Production d'un champ magnetique de l 600 000 At/m dans un milieu non magnetique dont le volume est 0,5 decimetre cube. Enroulement refroidi a l'hydrogene liquide (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Garin, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The eventual application of the technique of cryogenic coils for the production of magnetic fields for liquid hydrogen bubble chambers has led us to the study and construction of two copper coils (cooled in a bath of liquid hydrogen). Part one treats certain generalities concerning the resistivity of several pure metals at very low temperatures, the gain in power, thermal isolation and the choice of conductor and power supply. Part two describes the experimental arrangement. The last part is devoted to a description of the two coils which were constructed, and to the results obtained. (author) [French] L'application eventuelle de la technique des ''bobines cryogeniques'' aux chambres a bulles a hydrogene liquide pour la production du champ magnetique nous a conduits a l'etude et a la construction de deux bobines en cuivre (refroidies dans un bain d'hydrogene liquide). La premiere partie traite de generalites concernant la resistivite de quelques metaux purs, a tres basse temperature, le gain de puissance, l'isolement thermique et le choix du conducteur et de l'alimentation electrique. Dans la seconde partie on decrit l'installation d'essais. La derniere partie est consacree a la description des deux bobines realisees et aux resultats obtenus. (auteur)

  8. A generalized strategy for designing (19)F/(1)H dual-frequency MRI coil for small animal imaging at 4.7 Tesla.

    Science.gov (United States)

    Hu, Lingzhi; Hockett, Frank D; Chen, Junjie; Zhang, Lei; Caruthers, Shelton D; Lanza, Gregory M; Wickline, Samuel A

    2011-07-01

    To propose and test a universal strategy for building (19) F/(1) H dual-frequency RF coil that permits multiple coil geometries. The feasibility to design (19) F/(1) H dual-frequency RF coil based on coupled resonator model was investigated. A series capacitive matching network enables robust impedance matching for both harmonic oscillating modes of the coupled resonator. Two typical designs of (19) F/(1) H volume coils (birdcage and saddle) at 4.7T were implemented and evaluated with electrical bench test and in vivo (19) F/(1) H dual-nuclei imaging. For various combinations of internal resistances of the sample coil and secondary resonator, numerical solutions for the tunable capacitors to optimize impedance matching were obtained using a root-seeking program. Identical and homogeneous B1 field distribution at (19) F and (1) H frequencies were observed in bench test and phantom image. Finally, in vivo mouse imaging confirmed the sensitivity and homogeneity of the (19) F/(1) H dual-frequency coil design. A generalized strategy for designing (19) F/(1) H dual-frequency coils based on the coupled resonator approach was developed and validated. A unique feature of this design is that it preserves the B1 field homogeneity of the RF coil at both resonant frequencies. Thus it minimizes the susceptibility effect on image co-registration. Copyright © 2011 Wiley-Liss, Inc.

  9. A TMS coil positioning/holding system for MR image-guided TMS interleaved with fMRI.

    Science.gov (United States)

    Bohning, Daryl E; Denslow, S; Bohning, P A; Walker, J A; George, M S

    2003-11-01

    Transcranial magnetic stimulation (TMS) can be interleaved with fMRI to visualize regional brain activity in response to direct, non-invasive, cortical stimulation, making it a promising tool for studying brain function. A major practical difficulty is accurately positioning the TMS coil within the MRI scanner for stimulating a particular area of brain cortex. The objective of this work was to design and build a self-contained hardware/software system for MR-guided TMS coil positioning in interleaved TMS/fMRI studies. A compact, manually operated, articulated TMS coil positioner/holder with 6 calibrated degrees of freedom was developed for use inside a cylindrical RF head coil, along with a software package for transforming between MR image coordinates, MR scanner space coordinates, and positioner/holder settings. Phantom calibration studies gave an accuracy for positioning within setups of dx=+/-1.9 mm, dy=+/-1.4 mm, dz=+/-0.8 mm and a precision for multiple setups of dx=+/-0.8 mm, dy=+/-0.1 mm, dz=+/-0.1 mm. This self-contained, integrated MR-guided TMS system for interleaved TMS/fMRI studies provides fast, accurate location of motor cortex stimulation sites traditionally located functionally, and a means of consistent, anatomy-based TMS coil positioning for stimulation of brain areas without overt response.

  10. Tolerance Evaluation of Poloidal Shear Keys for ITER TF Coil

    International Nuclear Information System (INIS)

    Fu Youkun; Neil, M.; Cees Jong

    2006-01-01

    There are 18 ITER Toroidal Field (TF) Coils. Unlike the other ITER coils, these coils are structurally linked. These links consist of friction between the coil legs in the central vault formed by the inner straight legs of the coils, four outer inter-coil structures (OIS) and one inner inter-coil structure (IIS). The OIS consists essentially of bands around all 18 coils to provide shear support by forming shear panels with the coil case, and the IIS consists of poloidal circular keys placed directly between the coil cases. Global analysis of the 'perfect' coil shape has shown high stresses in the IIS, in the poloidal keyways. Optimization has successfully reduced these stresses to acceptable values as regards the expected fatigue resistance. However it is necessary to confirm that the stresses are still acceptable when realistic values of geometry variations are included (i.e. the effect of coil and case tolerances). Because of the extensive mechanical links between coils the poloidal key stresses can also be affected by tolerances elsewhere in the case. As the first step in assessment of the possible variations in stresses, a substructure technique is being used to develop a local model of the key region. The result of geometry variations between individual coils is a loss in the 18 fold symmetry used to simplify previous analyses. With the new and optimized model it should be possible to relax the 18-fold symmetry, but a full analysis of all 18 coils is still not possible. Systematic ways of representing the tolerance variation in the finite element model have been developed so that parametric studies can be undertaken without a full reconstruction of the model. (author)

  11. Exploring the conserved water site and hydration of a coiled-coil trimerisation motif: a MD simulation study.

    Science.gov (United States)

    Dolenc, Jozica; Baron, Riccardo; Missimer, John H; Steinmetz, Michel O; van Gunsteren, Wilfred F

    2008-07-21

    The solvent structure and dynamics around ccbeta-p, a 17-residue peptide that forms a parallel three-stranded alpha-helical coiled coil in solution, was analysed through 10 ns explicit solvent molecular dynamics (MD) simulations at 278 and 330 K. Comparison with two corresponding simulations of the monomeric form of ccbeta-p was used to investigate the changes of hydration upon coiled-coil formation. Pronounced peaks in the solvent density distribution between residues Arg8 and Glu13 of neighbouring helices show the presence of water bridges between the helices of the ccbeta-p trimer; this is in agreement with the water sites observed in X-ray crystallography experiments. Interestingly, this water site is structurally conserved in many three-stranded coiled coils and, together with the Arg and Glu residues, forms part of a motif that determines three-stranded coiled-coil formation. Our findings show that little direct correlation exists between the solvent density distribution and the temporal ordering of water around the trimeric coiled coil. The MD-calculated effective residence times of up to 40 ps show rapid exchange of surface water molecules with the bulk phase, and indicate that the solvent distribution around biomolecules requires interpretation in terms of continuous density distributions rather than in terms of discrete molecules of water. Together, our study contributes to understanding the principles of three-stranded coiled-coil formation.

  12. Unraveling double stranded alpha-helical coiled coils: an x-ray diffraction study on hard alpha-keratin fibers.

    Science.gov (United States)

    Kreplak, L; Doucet, J; Briki, F

    2001-04-15

    Transformations of proteins secondary and tertiary structures are generally studied in globular proteins in solution. In fibrous proteins, such as hard alpha-keratin, that contain long and well-defined double stranded alpha-helical coiled coil domains, such study can be directly done on the native fibrous tissue. In order to assess the structural behavior of the coiled coil domains under an axial mechanical stress, wide angle x-ray scattering and small angle x-ray scattering experiments have been carried out on stretched horse hair fibers at relative humidity around 30%. Our observations of the three major axial spacings as a function of the applied macroscopic strain have shown two rates. Up to 4% macroscopic strain the coiled coils were slightly distorted but retained their overall conformation. Above 4% the proportion of coiled coil domains progressively decreased. The main and new result of our study is the observation of the transition from alpha-helical coiled coils to disordered chains instead of the alpha-helical coiled coil to beta-sheet transition that occurs in wet fibers.

  13. CCBuilder: an interactive web-based tool for building, designing and assessing coiled-coil protein assemblies.

    Science.gov (United States)

    Wood, Christopher W; Bruning, Marc; Ibarra, Amaurys Á; Bartlett, Gail J; Thomson, Andrew R; Sessions, Richard B; Brady, R Leo; Woolfson, Derek N

    2014-11-01

    The ability to accurately model protein structures at the atomistic level underpins efforts to understand protein folding, to engineer natural proteins predictably and to design proteins de novo. Homology-based methods are well established and produce impressive results. However, these are limited to structures presented by and resolved for natural proteins. Addressing this problem more widely and deriving truly ab initio models requires mathematical descriptions for protein folds; the means to decorate these with natural, engineered or de novo sequences; and methods to score the resulting models. We present CCBuilder, a web-based application that tackles the problem for a defined but large class of protein structure, the α-helical coiled coils. CCBuilder generates coiled-coil backbones, builds side chains onto these frameworks and provides a range of metrics to measure the quality of the models. Its straightforward graphical user interface provides broad functionality that allows users to build and assess models, in which helix geometry, coiled-coil architecture and topology and protein sequence can be varied rapidly. We demonstrate the utility of CCBuilder by assembling models for 653 coiled-coil structures from the PDB, which cover >96% of the known coiled-coil types, and by generating models for rarer and de novo coiled-coil structures. CCBuilder is freely available, without registration, at http://coiledcoils.chm.bris.ac.uk/app/cc_builder/. © The Author 2014. Published by Oxford University Press.

  14. Appearance and impact of post-operative intracranial clips and coils on whole-brain CT angiography and perfusion

    International Nuclear Information System (INIS)

    Roach, Cayce J.; Russell, Cheryl L.; Hanson, Eric H.; Bluett, Brent; Orrison, William W.

    2012-01-01

    Background: To evaluate the effect of vascular clips and endovascular coils placed for intracranial aneurysms and arteriovenous malformations on whole-brain computed tomography (CT) angiography and perfusion. Methods: A 320-detector row dynamic volume CT system imaged 11 patients following surgical placement of vascular clips or endovascular coils. The extent of clip and coil subtraction by automated software was evaluated using CT digital subtraction angiography and CT perfusion. Impact on CT perfusion values by retained intracranial devices was compared to age- and gender-matched controls. Results: Clip and coil subtraction on CT angiography was graded as good in 8 and moderate in 3 cases. A residual neck and additional aneurysm were noted in 1 of 11 patients. Post-procedural axial slice level CT perfusion values decreased in reliability with increasing proximity to the metallic devices secondary to beam hardening. However, the intracranial devices did not affect axial slice level CTP values of cerebral blood volume, cerebral blood flow and mean transit time outside of the level of the device. Time to peak values was globally decreased outside of the immediate vascular intervention region. Conclusions: Advances in CT technology have provided clinically useful subtraction of intracranial clips and coils. While CT perfusion values were altered in device subtraction areas and within beam hardening artifact areas; they can provide valuable postoperative information on whole-brain hemodynamics. In selected cases, the combination of CT angiography and whole-brain CT perfusion can offer an alternative to conventional angiography that is a more invasive option.

  15. Physiological Studies on Pea Tendrils. IV. Flavonoids and Contact Coiling

    Science.gov (United States)

    Jaffe, M. J.; Galston, A. W.

    1967-01-01

    Pea tendrils contain high concentrations of flavonoids, mainly quercetin-triglucosyl-p-coumarate (QGC). QGC is most abundant near the highly responsive apex of the tendril, and least abundant at the base. After mechanical stimulation, and during coiling of the tendril, the QGC titer drops to about 30% of its original value. The kinetics of flavonoid disappearance are significantly correlated with the kinetics of coiling. Aqueous extracts of unstimulated pea tendrils or 10 μm QGC inhibit contact coiling of excised tendrils. Extracts of coiled tendrils do not. The evidence indicates a possible regulatory role for flavonoids in contact coiling. PMID:16656581

  16. Superconducting coil system and methods of assembling the same

    Science.gov (United States)

    Rajput-Ghoshal, Renuka; Rochford, James H.; Ghoshal, Probir K.

    2016-01-19

    A superconducting magnet apparatus is provided. The superconducting magnet apparatus includes a power source configured to generate a current; a first switch coupled in parallel to the power source; a second switch coupled in series to the power source; a coil coupled in parallel to the first switch and the second switch; and a passive quench protection device coupled to the coil and configured to by-pass the current around the coil and to decouple the coil from the power source when the coil experiences a quench.

  17. The IEA large coil task test results in IFSMTF

    International Nuclear Information System (INIS)

    Lubell, M.S.; Clinard, J.A.; Dresner, L.

    1987-01-01

    The Large Coil Task (LCT) is an international collaboration of the United States, EURATOM, Japan, and Switzerland to develop large superconducting magnets for fusion reactors. The testing phase of LCT was completed on September 3, 1987. All six coils exceeded the design goals, both as single coils and in six-coil toroidal tests. In addition, a symmetric torus test was performed in which a maximum field of 9 T was reached in all coils simultaneously. These are by far the largest magnets (either in size, weight, or stored energy) ever to achieve such a field. 6 refs., 6 figs., 3 tabs

  18. Random coil chemical shift for intrinsically disordered proteins

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Brander, Søren; Poulsen, Flemming Martin

    2011-01-01

    . Temperature has a non-negligible effect on the (13)C random coil chemical shifts, so temperature coefficients are reported for the random coil chemical shifts to allow extrapolation to other temperatures. The pH dependence of the histidine random coil chemical shifts is investigated in a titration series......, which allows the accurate random coil chemical shifts to be obtained at any pH. By correcting the random coil chemical shifts for the effects of temperature and pH, systematic biases of the secondary chemical shifts are minimized, which will improve the reliability of detection of transient secondary...

  19. SSC [Superconducting Super Collider] dipole coil production tooling

    International Nuclear Information System (INIS)

    Carson, J.A.; Barczak, E.J.; Bossert, R.C.; Brandt, J.S.; Smith, G.A.

    1989-03-01

    Superconducting Super Collider dipole coils must be produced to high precision to ensure uniform prestress and even conductor distribution within the collared coil assembly. Tooling is being prepared at Fermilab for the production of high precision 1M and 16.6M SSC dipole coils suitable for mass production. The design and construction methods builds on the Tevatron tooling and production experience. Details of the design and construction methods and measured coil uniformity of 1M coils will be presented. 4 refs., 10 figs

  20. Tight aspect ratio tokamak power reactor with superconducting TF coils

    International Nuclear Information System (INIS)

    Nishio, S.; Tobita, K.; Konishi, S.; Ando, T.; Hiroki, S.; Kuroda, T.; Yamauchi, M.; Azumi, M.; Nagata, M.

    2003-01-01

    Tight aspect ratio tokamak power reactor with super-conducting toroidal field (TF) coils has been proposed. A center solenoid coil system and an inboard blanket were discarded. The key point was how to find the engineering design solution of the TF coil system with the high field and high current density. The coil system with the center post radius of less than 1 m can generate the maximum field of ∼ 20 T. This coil system causes a compact reactor concept, where the plasma major and minor radii of 3.75 m and 1.9 m, respectively and the fusion power of 1.8 GW. (author)