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1

Accuracy for detection of simulated lesions: comparison of fluid-attenuated inversion-recovery, proton density--weighted, and T2-weighted synthetic brain MR imaging  

NASA Technical Reports Server (NTRS)

OBJECTIVE: The objective of our study was to determine the effects of MR sequence (fluid-attenuated inversion-recovery [FLAIR], proton density--weighted, and T2-weighted) and of lesion location on sensitivity and specificity of lesion detection. MATERIALS AND METHODS: We generated FLAIR, proton density-weighted, and T2-weighted brain images with 3-mm lesions using published parameters for acute multiple sclerosis plaques. Each image contained from zero to five lesions that were distributed among cortical-subcortical, periventricular, and deep white matter regions; on either side; and anterior or posterior in position. We presented images of 540 lesions, distributed among 2592 image regions, to six neuroradiologists. We constructed a contingency table for image regions with lesions and another for image regions without lesions (normal). Each table included the following: the reviewer's number (1--6); the MR sequence; the side, position, and region of the lesion; and the reviewer's response (lesion present or absent [normal]). We performed chi-square and log-linear analyses. RESULTS: The FLAIR sequence yielded the highest true-positive rates (p < 0.001) and the highest true-negative rates (p < 0.001). Regions also differed in reviewers' true-positive rates (p < 0.001) and true-negative rates (p = 0.002). The true-positive rate model generated by log-linear analysis contained an additional sequence-location interaction. The true-negative rate model generated by log-linear analysis confirmed these associations, but no higher order interactions were added. CONCLUSION: We developed software with which we can generate brain images of a wide range of pulse sequences and that allows us to specify the location, size, shape, and intrinsic characteristics of simulated lesions. We found that the use of FLAIR sequences increases detection accuracy for cortical-subcortical and periventricular lesions over that associated with proton density- and T2-weighted sequences.

Herskovits, E. H.; Itoh, R.; Melhem, E. R.

2001-01-01

2

Boosting BOLD fMRI by K-Space Density Weighted Echo Planar Imaging  

PubMed Central

Functional magnetic resonance imaging (fMRI) has become a powerful and influential method to non-invasively study neuronal brain activity. For this purpose, the blood oxygenation level-dependent (BOLD) effect is most widely used. T2* weighted echo planar imaging (EPI) is BOLD sensitive and the prevailing fMRI acquisition technique. Here, we present an alternative to its standard Cartesian recordings, i.e. k-space density weighted EPI, which is expected to increase the signal-to-noise ratio in fMRI data. Based on in vitro and in vivo pilot measurements, we show that fMRI by k-space density weighted EPI is feasible and that this new acquisition technique in fact boosted spatial and temporal SNR as well as the detection of local fMRI activations. Spatial resolution, spatial response function and echo time were identical for density weighted and conventional Cartesian EPI. The signal-to-noise ratio gain of density weighting can improve activation detection and has the potential to further increase the sensitivity of fMRI investigations.

Zeller, Mario; Muller, Alexander; Gutberlet, Marcel; Nichols, Thomas; Hahn, Dietbert; Kostler, Herbert; Bartsch, Andreas J.

2013-01-01

3

A geometric flow for segmenting vasculature in proton-density weighted MRI.  

PubMed

Modern neurosurgery takes advantage of magnetic resonance images (MRI) of a patient's cerebral anatomy and vasculature for planning before surgery and guidance during the procedure. Dual echo acquisitions are often performed that yield proton-density (PD) and T2-weighted images to evaluate edema near a tumor or lesion. In this paper we develop a novel geometric flow for segmenting vasculature in PD images, which can also be applied to the easier cases of MR angiography data or Gadolinium enhanced MRI. Obtaining vasculature from PD data is of clinical interest since the acquisition of such images is widespread, the scanning process is non-invasive, and the availability of vessel segmentation methods could obviate the need for an additional angiographic or contrast-based sequence during preoperative imaging. The key idea is to first apply Frangi's vesselness measure [Frangi, A., Niessen, W., Vincken, K.L., Viergever, M.A., 1998. Multiscale vessel enhancement filtering. In: International Conference on Medical Image Computing and Computer Assisted Intervention, vol. 1496 of Lecture Notes in Computer Science, pp. 130-137] to find putative centerlines of tubular structures along with their estimated radii. This measure is then distributed to create a vector field which allows the flux maximizing flow algorithm of Vasilevskiy and Siddiqi [Vasilevskiy, A., Siddiqi, K., 2002. Flux maximizing geometric flows. IEEE Transactions on Pattern Analysis and Machine Intelligence 24 (12), 1565-1578] to be applied to recover vessel boundaries. We carry out a qualitative validation of the approach on PD, MR angiography and Gadolinium enhanced MRI volumes and suggest a new way to visualize the segmentations in 2D with masked projections. We validate the approach quantitatively on a single-subject data set consisting of PD, phase contrast (PC) angiography and time of flight (TOF) angiography volumes, with an expert segmented version of the TOF volume viewed as the ground truth. We then validate the approach quantitatively on 19 PD data sets from a new digital brain phantom, with semi-automatically obtained labels from the corresponding angiography volumes viewed as ground truth. A significant finding is that both for the single-subject and multi-subject studies, 90% or more of the vasculature in the ground truth segmentation is recovered from the automatic segmentation of the other volumes. PMID:18375175

Descoteaux, Maxime; Collins, D Louis; Siddiqi, Kaleem

2008-08-01

4

Improve definition of titanium tandems in MR-guided high dose rate brachytherapy for cervical cancer using proton density weighted MRI  

PubMed Central

Background For cervical cancer patients treated with MR-guided high dose rate brachytherapy, the accuracy of radiation delivery depends on accurate localization of both tumors and the applicator, e.g. tandem and ovoid. Standard T2-weighted (T2W) MRI has good tumor-tissue contrast. However, it suffers from poor uterus-tandem contrast, which makes the tandem delineation very challenging. In this study, we evaluated the possibility of using proton density weighted (PDW) MRI to improve the definition of titanium tandems. Methods Both T2W and PDW MRI images were obtained from each cervical cancer patient. Imaging parameters were kept the same between the T2W and PDW sequences for each patient except the echo time (90 ms for T2W and 5.5 ms for PDW) and the slice thickness (0.5 cm for T2W and 0.25 cm for PDW). Uterus-tandem contrast was calculated by the equation C = (Su-St)/Su, where Su and St represented the average signal in the uterus and the tandem, respectively. The diameter of the tandem was measured 1.5 cm away from the tip of the tandem. The tandem was segmented by the histogram thresholding technique. Results PDW MRI could significantly improve the uterus-tandem contrast compared to T2W MRI (0.42±0.24 for T2W MRI, 0.77±0.14 for PDW MRI, p=0.0002). The average difference between the measured and physical diameters of the tandem was reduced from 0.20±0.15 cm by using T2W MRI to 0.10±0.11 cm by using PDW MRI (p=0.0003). The tandem segmented from the PDW image looked more uniform and complete compared to that from the T2W image. Conclusions Compared to the standard T2W MRI, PDW MRI has better uterus-tandem contrast. The information provided by PDW MRI is complementary to those provided by T2W MRI. Therefore, we recommend adding PDW MRI to the simulation protocol to assist tandem delineation process for cervical cancer patients.

2013-01-01

5

Towards a proton imaging system  

NASA Astrophysics Data System (ADS)

Hadron therapy for tumor treatment is nowadays used in several medical centres. The main advantage in using protons or light ions beams is the possibility of tightly shaping the radiation dose to the target volume. Presently the spatial accuracy of the therapy is limited by the uncertainty in stopping power distribution, which is derived, for each treatment, from the photon attenuation coefficients measured by X-ray tomography. A direct measurement of the stopping powers will help in reducing this uncertainty. This can be achieved by using a proton beam and a detection system able to reconstruct a tomography image of the patient. As a first step towards such a system an apparatus able to perform a proton transmission radiography (pCR) has been designed. It consists of a silicon microstrip tracker, measuring proton trajectories, and a YAG:Ce calorimeter to determine the particle residual energy. Proton beam and laboratory tests have been performed on the system components prototypes: the main results will be shown and discussed.

Civinini, C.; Brianzi, M.; Bruzzi, M.; Bucciolini, M.; Candiano, G.; Capineri, L.; Cirrone, G. A. P.; Cuttone, G.; Lo Presti, D.; Marrazzo, L.; Mazzaglia, E.; Menichelli, D.; Pieri, S.; Randazzo, N.; Sipala, V.; Stancampiano, C.; Talamonti, C.; Tesi, M.; Valentini, S.

2010-11-01

6

Proton therapy verification with PET imaging.  

PubMed

Proton therapy is very sensitive to uncertainties introduced during treatment planning and dose delivery. PET imaging of proton induced positron emitter distributions is the only practical approach for in vivo, in situ verification of proton therapy. This article reviews the current status of proton therapy verification with PET imaging. The different data detecting systems (in-beam, in-room and off-line PET), calculation methods for the prediction of proton induced PET activity distributions, and approaches for data evaluation are discussed. PMID:24312147

Zhu, Xuping; El Fakhri, Georges

2013-01-01

7

Proton Magnetic Resonance Imaging of Flowing Blood.  

NASA Astrophysics Data System (ADS)

A novel technique of making angiographic images non-invasively by NMR is introduced. In order to visualize the vascular structure, flowing blood must be labeled to achieve contrast against background static tissue. In this technique, a little surface coil is used as the labeling device in addition to a whole-body NMR imager. To label the flowing blood, a magnetic field gradient is applied along the long axis of a living subject. The labeling coil over a carotid artery in the neck is fed RF at the resonant frequency of the protons under the coil. Arterial flow moves blood protons from a field below resonance (at the heart), steadily passing through resonance (at the neck) to a field high above resonance (in the head); at the end of the event blood protons are inverted, or labeled by an adiabatic fast passage. Meanwhile, protons in stationary tissue feel only a constant field and remain unaffected. Blood retains this label as it flows downstream into the head and gives a negative signal, while protons in other tissue a positive signal. Two projection images of the head, with and without labeling, are obtained and subtracted digitally. The residue of the subtraction shows moving material only since signals arising from static material are identical and are cancelled in the subtraction process. Finally, the three dimensional vascular structure is presented in a projective format onto a two dimensional plane resembling an angiogram produced with dye injection and X-rays. Pulse sequences specially designed to image moving objects are presented and discussed. Experimental results on phantoms, volunteers and patients are demonstrated. Competing techniques by NMR are reviewed and compared.

Du, Leila Ning-Zhi

1987-09-01

8

Metabolite specific proton magnetic resonance imaging  

SciTech Connect

An imaging method is described that makes use of proton double quantum nuclear magnetic resonance (NMR) to construct images based on selected metabolites such as lactic acid. The optimization of the method is illustrated in vitro, followed by in vivo determination of lactic acid distribution in a solid tumor model. Water suppression and editing of lipid signals are such that two-dimensional spectra of lactic acid may be obtained from a radiation-induced fibrosarcoma (RIF-1) tumor in under 1 min and lactic acid images from the same tumor in under 1 hr at 2.0 T. This technique provides a fast and reproducible method at moderate magnetic field strength for mapping biologically relevant metabolites.

Hurd, R.E.; Freeman, D.M.

1989-06-01

9

Relativistic protons for image-guided stereotactic radiosurgery  

NASA Astrophysics Data System (ADS)

Bragg-peak radiosurgery and proton radiography have been used in radiotherapy over the past few years. Non-Bragg-peak (plateau) relativistic protons (E>1 GeV) can offer advantages both in terms of precision and target margin reduction, and especially thanks to the possible simultaneous use of high-resolution online proton radiography. Here we will present initial simulations and experiments toward image-guided stereotactic radiosurgery using GeV protons.

Durante, M.; Stöcker, H.

2012-07-01

10

Ultrafast laser-driven proton sources and dynamic proton imaging  

SciTech Connect

Ion bursts, accelerated by an ultrafast (40 fs) laser-assisted target normal sheath acceleration mechanism, can be adjusted so as to deliver a nearly pure proton beam. Such laser-driven proton bursts have predominantly a low transverse emittance and a broad kinetic spectrum suitable for continuous probing of the temporal evolution of spatially extended electric fields that arise after laser irradiation of thin foils. Fields with a strength of up to 10{sup 10} V/m were measured with a new streaklike proton deflectometry setup. The data show the temporal and spatial evolution of electric fields that are due to target charge-up and ion-front expansion following intense laser-target interaction at intensities of 10{sup 17}-10{sup 18} W/cm{sup 2}. Measurement of the field evolution is important to gain further insight into lateral electron-transport processes and the influence of field dynamics on ion beam properties.

Nickles, Peter V.; Schnuerer, Matthias; Sokollik, Thomas; Ter-Avetisyan, Sargis; Sandner, Wolfgang [Max Born Institut, Max-Born-Strasse 2a, D12489 Berlin (Germany); Amin, Munib; Toncian, Toma; Willi, Oswald [Heinrich Heine Universitaet, Universitaetstrasse 1, D-40225 Duesseldorf (Germany); Andreev, Alexander [Max Born Institut, Max-Born-Strasse 2a, D12489 Berlin (Germany); Institute for Laser Physics, 12 Birzhevaya line, St. Petersburg 199034 (Russian Federation)

2008-07-15

11

Density Weighted FDF Equations for Simulations of Turbulent Reacting Flows  

NASA Technical Reports Server (NTRS)

In this report, we briefly revisit the formulation of density weighted filtered density function (DW-FDF) for large eddy simulation (LES) of turbulent reacting flows, which was proposed by Jaberi et al. (Jaberi, F.A., Colucci, P.J., James, S., Givi, P. and Pope, S.B., Filtered mass density function for Large-eddy simulation of turbulent reacting flows, J. Fluid Mech., vol. 401, pp. 85-121, 1999). At first, we proceed the traditional derivation of the DW-FDF equations by using the fine grained probability density function (FG-PDF), then we explore another way of constructing the DW-FDF equations by starting directly from the compressible Navier-Stokes equations. We observe that the terms which are unclosed in the traditional DW-FDF equations are now closed in the newly constructed DW-FDF equations. This significant difference and its practical impact on the computational simulations may deserve further studies.

Shih, Tsan-Hsing; Liu, Nan-Suey

2011-01-01

12

Suppression of lipid artifacts in amide proton transfer imaging.  

PubMed

Amide proton transfer (APT) imaging is a type of chemical exchange saturation transfer imaging in which the amide protons of cellular proteins and peptides are saturated and detected via the water resonance. To study this effect, conventional magnetization transfer and direct saturation effects in the frequency-dependent water saturation spectrum (z-spectrum) need to be removed by asymmetry analysis with respect to the water frequency offset. When using echo planar imaging, it was found that unequal pericranial fat saturation at equidistant higher and lower frequencies with respect to water leads to a lipid artifact in APT asymmetry images. It is demonstrated that a chemical-shift-selective refocusing pulse in combination with crusher gradients can suppress this artifact and provide high-quality images. PMID:15968669

Sun, Phillip Zhe; Zhou, Jinyuan; Sun, Weiyun; Huang, Judy; van Zijl, Peter C M

2005-07-01

13

Laser-driven proton sources and their applications: femtosecond intense laser plasma driven simultaneous proton and x-ray imaging  

Microsoft Academic Search

We have performed simultaneous proton and X-ray imaging with an ultra-short and high-intensity Ti: Sap laser system. More than 1010 protons, whose maximum energy reaches 2.5 MeV, were delivered within a ~ps bunch. At the same time, keV X-ray is generated at almost the same place where protons are emitted. We have performed the simultaneous imaging of the copper mesh

M. Nishiuchi; H. Daido; A. Yogo; A. Sagisaka; K. Ogura; S. Orimo; M. Mori; J. Ma; A. S. Pirozhkov; H. Kiriyama; S. Kanazawa; S. Kondo; Y. Yamamoto; T. Shimoura; M. Tanoue; Y. Nakai; A. Akutsu; A. Nagashima; S. V. Bulanov; T. Z. Esirkepov; T. Kimura; T. Tajima; K. Nemoto; Y. Oishi; T. Nayuki; T. Fujii; A. Noda; Y. Iwashita; T. Shirai; S. Nakamura; I. W. Choi; T. J. Yu; J. H. Sung; H. T. Kim; T. M. Jeong; K.-H. Hong; Y.-C. Noh; D.-K. Ko; J. Lee

2008-01-01

14

Fabrication of fine imaging devices using an external proton microbeam  

NASA Astrophysics Data System (ADS)

We have successfully fabricated novel microscopic imaging devices made from UV/EB curable resin using an external scanning proton microbeam. The devices are micro-structured fluorescent plates that consist of an array of micro-pillars that align periodically. The base material used in the pillars is UV/EB curable resin and each pillar contains phosphor grains. The pattern exposures were performed using a proton beam writing technique. The height of the pillars depends on the range of the proton beam. Optical microscopy and scanning electron microscopy have been used to characterize the samples. The results show that the fabricated fluorescent plates are expected to be compatible with both spatial resolution and detection efficiency.

Sakai, T.; Yasuda, R.; Iikura, H.; Nojima, T.; Koka, M.; Satoh, T.; Ishii, Y.; Oshima, A.

2014-08-01

15

Method and apparatus for imaging through 3-dimensional tracking of protons  

NASA Technical Reports Server (NTRS)

A method and apparatus for creating density images of an object through the 3-dimensional tracking of protons that have passed through the object are provided. More specifically, the 3-dimensional tracking of the protons is accomplished by gathering and analyzing images of the ionization tracks of the protons in a closely packed stack of scintillating fibers.

Ryan, James M. (Inventor); Macri, John R. (Inventor); McConnell, Mark L. (Inventor)

2001-01-01

16

Imaging detector systems for soft x-ray and proton radiography  

Microsoft Academic Search

Multi-pulse imaging systems have been developed for recording images from pulsed X-ray and proton radiographic sources. The number of successive images for x-ray radiography is limited to four being generated by 25 ns, pulsed sources in a close positioned geometry. The number of proton images are provided by the number of proton bursts (approximately 60 ns) delivered to the radiographic

Nicholas S. P. King; Stuart A. Baker; Steven A. Jaramillo; Kris Kwiatkowski; Stephen S. Lutz; Gary E. Hogan; Vanner H. Holmes; Christopher L. Morris; Paul T. Nedrow; Peter D. Pazuchanics; John S. Rohrer; Dan S. Sorenson; Richard T. Thompson

2003-01-01

17

Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging  

Microsoft Academic Search

PURPOSE: To prospectively determine the accuracies of T2-weighted magnetic resonance (MR) imaging, dynamic contrast material-enhanced MR imaging, and quantitative three-dimensional (3D) proton MR spectroscopic imaging of the entire prostate for prostate cancer localization, with whole-mount histopathologic section findings as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from

J. J. Futterer; S. W. T. P. J. Heijmink; T. W. J. Scheenen; J. Veltman; H. J. Huisman; P. E. Vos; C. A. Hulsbergen-van de Kaa; J. A. Witjes; P.F.M. Krabbe; A. Heerschap; J. O. Barentsz

2006-01-01

18

Reliability of proton-nuclear interaction cross section data to predict proton-induced PET images in proton therapy  

PubMed Central

In-vivo PET range verification relies on the comparison of measured and simulated activity distributions. The accuracy of the simulated distribution depends on the accuracy of the Monte Carlo code, which is in turn dependent on the accuracy of the available cross sections data for ?+ isotope production. We have explored different cross section data available in the literature for the main reaction channels (16O(p,pn)15O, 12C(p,pn)11C and 16O(p,3p3n)11C) contributing to the production of ?+ isotopes by proton beams in patients. Available experimental and theoretical values were implemented in the simulation and compared with measured PET images obtained with a high-resolution PET scanner. Each reaction channel was studied independently. A phantom with three different materials was built, two of them with high carbon or oxygen concentration and a third one with average soft tissue composition. Monoenergetic and SOBP field irradiations of the phantom were accomplished and measured PET images were compared with simulation results. Different cross section values for the tissue-equivalent material lead to range differences below 1 mm when a 5 min scan time was employed and close to 5 mm differences for a 30 min scan time with 15 min delay between irradiation and scan (a typical off-line protocol). The results presented here emphasize the need of more accurate measurement of the cross section values of the reaction channels contributing to the production of PET isotopes by proton beams before this in-vivo range verification method can achieve mm accuracy.

Espana, S; Zhu, X; Daartz, J; El Fakhri, G; Bortfeld, T

2011-01-01

19

The first proton NMR imaging of ice: stray-field imaging and relaxation studies.  

PubMed

A proton magnetic resonance image of ice was observed with the stray-field (STRAFI) technique. A preliminary study of proton relaxation times was performed in water and ice, at different temperatures. For example, a value of 3.5 micros for the spin-spin relaxation time, T(2), was found in ice at 258 K. Such a short T(2) value leads to significant signal loss, as compared to liquid water, and to a shortening of the STRAFI echo-trains. In particular, a STRAFI signal for protons in ice could be observed only at echo times as short as 15 and 25 micros, for RF pulse durations corresponding to 90 degrees and 50 degrees magnetisation tip angles, respectively. This behaviour is in contrast with that of deuteriated water. Imaging ice, as shown here, opens new prospects in studies involving environmental and materials science, for example. PMID:17905572

Nunes, T G; Randall, E W; Guillot, G

2007-10-01

20

Magnetic Resonance Imaging of Acute Stroke  

Microsoft Academic Search

In the investigation of ischemic stroke, conventional structural magnetic resonance (MR) techniques (e.g., T1-weighted imaging, T2-weighted imaging, and proton density-weighted imaging) are valuable for the assessment of infarct extent and location beyond the first 12 to 24 hours after onset, and can be combined with MR angiography to noninvasively assess the intracranial and extracranial vasculature. However, during the critical first

Alison E. Baird; Steven Warach

1998-01-01

21

Monitoring proton radiation therapy with in-room PET imaging  

PubMed Central

Purpose We used a mobile PET scanner positioned within the proton therapy treatment room to study the feasibility of proton range verification with an in-room, stand-alone PET system, and compared with off-line equivalent studies. Methods and materials Two subjects with adenoid cystic carcinoma were enrolled into a pilot study in which in-room PET scans were acquired in list-mode after a routine fractionated treatment session. The list-mode PET data were reconstructed with different time schemes to generate in-room short, in-room long and off-line equivalent (by skipping coincidences from the first 15 minutes during the list-mode reconstruction) PET images for comparison in activity distribution patterns. A phantom study was followed to evaluate the accuracy of range verification for different reconstruction time schemes quantitatively. Results The in-room PET has a higher sensitivity compared to the off-line modality so that the PET acquisition time can be greatly reduced from 30 min to <5 min. Features in deep-site, soft-tissue regions were better retained with in-room short PET acquisitions because of the collection of 15O component and lower biological washout. For soft tissue-equivalent material, the distal fall-off edge of an in-room short acquisition is deeper compared to an off-line equivalent scan, indicating a better coverage of the high-dose end of the beam. Conclusions In-room PET is a promising low cost, high sensitivity modality for the in vivo verification of proton therapy. Better accuracy in Monte Carlo predictions, especially for biological decay modeling, is necessary.

Zhu, Xuping; Espana, Samuel; Daartz, Juliane; Liebsch, Norbert; Ouyang, Jinsong; Paganetti, Harald; Bortfeld, Thomas R; El Fakhri, Georges

2011-01-01

22

Monitoring proton radiation therapy with in-room PET imaging.  

PubMed

We used a mobile positron emission tomography (PET) scanner positioned within the proton therapy treatment room to study the feasibility of proton range verification with an in-room, stand-alone PET system, and compared with off-line equivalent studies. Two subjects with adenoid cystic carcinoma were enrolled into a pilot study in which in-room PET scans were acquired in list-mode after a routine fractionated treatment session. The list-mode PET data were reconstructed with different time schemes to generate in-room short, in-room long and off-line equivalent (by skipping coincidences from the first 15 min during the list-mode reconstruction) PET images for comparison in activity distribution patterns. A phantom study was followed to evaluate the accuracy of range verification for different reconstruction time schemes quantitatively. The in-room PET has a higher sensitivity compared to the off-line modality so that the PET acquisition time can be greatly reduced from 30 to <5 min. Features in deep-site, soft-tissue regions were better retained with in-room short PET acquisitions because of the collection of (15)O component and lower biological washout. For soft tissue-equivalent material, the distal fall-off edge of an in-room short acquisition is deeper compared to an off-line equivalent scan, indicating a better coverage of the high-dose end of the beam. In-room PET is a promising low cost, high sensitivity modality for the in vivo verification of proton therapy. Better accuracy in Monte Carlo predictions, especially for biological decay modeling, is necessary. PMID:21677366

Zhu, Xuping; España, Samuel; Daartz, Juliane; Liebsch, Norbert; Ouyang, Jinsong; Paganetti, Harald; Bortfeld, Thomas R; El Fakhri, Georges

2011-07-01

23

Trapped and precipitating protons in the inner magnetosphere as seen by IMAGE  

NASA Astrophysics Data System (ADS)

Images from the IMAGE satellite of precipitating protons (SU12/FUV) and trapped protons at 8.5 (MENA) and 33 keV (HENA) are compared during three periods: (1) 12 August 2000 from 1000 UT to 1145 UT just after the peak of a strong geomagnetic storm, (2) 2 June 2001 from 0100 to 0345 UT during the main phase and initial recovery of a weak storm, and (3) 18 June 2001 from 1400 to 1645 UT late in the recovery phase of another weak storm. Some of the features of the precipitating and trapped protons observed in these time intervals have been previously reported for other events, especially the fact that the strength of the precipitating protons and trapped protons do not always correlate. The primary new features are that (1) the fluxes of the precipitating protons and both the 8.5 keV and 33 keV trapped protons peak at similar magnetic latitudes and that (2) the peak in the 8.5 keV trapped protons is usually at the same MLT as the peak in the precipitating protons, while the peak in the 33 keV trapped protons is usually in a different MLT region than the peak of the precipitating protons. Some possible mechanisms to explain these observations are presented, but understanding this behavior should provide stringent tests for models of the Earth's inner magnetosphere.

Perez, J. D.; Zhang, X.-X.; C:Son Brandt, P.; Mitchell, D. G.; Jahn, J.-M.; Pollock, C. J.; Mende, S. B.

2004-09-01

24

An imaging proton spectrometer for short-pulse laser plasma experiments  

SciTech Connect

Ultra intense short pulse laser pulses incident on solid targets can generate energetic protons. In additions to their potentially important applications such as in cancer treatments and proton fast ignition, these protons are essential to understand the complex physics of intense laser plasma interaction. To better characterize these laser-produced protons, we designed and constructed a novel, spatially imaging proton spectrometer that will not only measure proton energy distribution with high resolution, but also provide its angular characteristics. The information obtained from this spectrometer compliments those from commonly used diagnostics including radiochromic film packs, CR39 nuclear track detectors, and non-imaging magnetic spectrometers. The basic characterizations and sample data from this instrument are presented.

Chen, H; Hazi, A; van Maren, R; Chen, S; Fuchs, J; Gauthier, M; Pape, S L; Rygg, J R; Shepherd, R

2010-05-11

25

Invited Article: Relation between electric and magnetic field structures and their proton-beam images  

SciTech Connect

Proton imaging is commonly used to reveal the electric and magnetic fields that are found in high energy density plasmas. Presented here is an analysis of this technique that is directed towards developing additional insight into the underlying physics. This approach considers: formation of images in the limits of weak and strong intensity variations; caustic formation and structure; image inversion to obtain line-integrated field characteristics; direct relations between images and electric or magnetic field structures in a plasma; imaging of sharp features such as Debye sheaths and shocks. Limitations on spatial and temporal resolution are assessed, and similarities with optical shadowgraphy are noted. Synthetic proton images are presented to illustrate the analysis. These results will be useful for quantitatively analyzing experimental proton imaging data and verifying numerical codes.

Kugland, N. L.; Ryutov, D. D.; Plechaty, C.; Ross, J. S.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

2012-10-15

26

Multi level RTS in proton irradiated CMOS image sensors manufactured in deep submicron technology  

Microsoft Academic Search

A new automated method able to detect multi level random telegraph signals in pixel arrays and to extract their main characteristics is presented. The proposed method is applied to several proton irradiated pixel arrays manufactured using a 0.18 ?m CMOS process dedicated to imaging. Despite the large proton energy range and the large fluence range used, similar exponential RTS amplitude

V. Goiffon; G. R. Hopkinson; P. Magnan; F. Bernard; G. Roland; O. Saint-Pe

2008-01-01

27

Multilevel RTS in Proton Irradiated CMOS Image Sensors Manufactured in a Deep Submicron Technology  

Microsoft Academic Search

A new automated method able to detect multilevel random telegraph signals (RTS) in pixel arrays and to extract their main characteristics is presented. The proposed method is applied to several proton irradiated pixel arrays manufactured using a 0.18 mum CMOS process dedicated to imaging. Despite the large proton energy range and the large fluence range used, similar exponential RTS amplitude

V. Goiffon; G. R. Hopkinson; P. Magnan; F. Bernard; G. Rolland; O. Saint-Pe

2009-01-01

28

Electric field detection in laser-plasma interaction experiments via the proton imaging technique  

Microsoft Academic Search

Due to their particular properties^1, the beams of multi-MeV protons generated during the interaction of ultraintense short pulses with solid targets are most suited for use as a particle probe in laser-plasma experiments. The recently developed proton imaging technique^2 employs the beams, in a point-projection imaging scheme, as a diagnostic tool for the detection of electric fields in laser-plasma interaction

Marco Borghesi

2001-01-01

29

Electric field detection in laser-plasma interaction experiments via the proton imaging technique  

Microsoft Academic Search

Due to their particular properties, the beams of the multi-MeV protons generated during the interaction of ultraintense (I>1019 W\\/cm2) short pulses with thin solid targets are most suited for use as a particle probe in laser-plasma experiments. The recently developed proton imaging technique employs the beams in a point-projection imaging scheme as a diagnostic tool for the detection of electric

M. Borghesi; D. H. Campbell; A. Schiavi; M. G. Haines; O. Willi; A. J. MacKinnon; P. Patel; L. A. Gizzi; M. Galimberti; R. J. Clarke; F. Pegoraro; H. Ruhl; S. Bulanov

2002-01-01

30

Proton spectroscopic imaging of the human prostate at 7 T.  

PubMed

The sensitivity of proton MR Spectroscopic Imaging ((1)H-MRSI) of the prostate can be optimized by using the high magnetic field strength of 7 T in combination with an endorectal coil. In the work described in this paper we introduce an endorectal transceiver at 7 T, validate its safety for in vivo use and apply a pulse sequence, optimized for three-dimensional (3D) (1)H-MRSI of the human prostate at 7 T. A transmit/receive endorectal RF coil was adapted from a commercially available 3 T endorectal receive-only coil and validated to remain within safety guidelines for radiofrequency (RF) power deposition using numerical models, MR thermometry of phantoms, and in vivo temperature measurements. The (1)H-MRSI pulse sequence used adiabatic slice selective refocusing pulses and frequency-selective water and lipid suppression to selectively obtain the relevant metabolite signals from the prostate. Quantum mechanical simulations were used to adjust the inter-pulse timing for optimal detection of the strongly coupled spin system of citrate resulting in an echo time of 56 ms. Using this endorectal transceiver and pulse sequence with slice selective adiabatic refocusing pulses, 3D (1)H-MRSI of the human prostate is feasible at 7 T with a repetition time of 2 s. The optimized inter-pulse timing enables the absorptive detection of resonances of spins from spermine and citrate in phase with creatine and choline. These potential tumor markers may improve the in vivo detection, localization, and assessment of prostate cancer. PMID:19170072

Klomp, D W J; Bitz, A K; Heerschap, A; Scheenen, T W J

2009-06-01

31

The Relationship Between Proton Aurora and Trapped Ion Flux as Seen by IMAGE  

NASA Astrophysics Data System (ADS)

The FUV/SI12 instrument on board the IMAGE satellite provides global observations of proton produced aurora. The MENA and HENA instruments on IMAGE provide global energetic neutral atom images that can be inverted to obtain equatorial flux distributions of trapped ring current protons. Mapping the equatorial distributions of trapped protons along magnetic field lines to the polar cap where the proton auroras are observed allows direct comparison of the location of the two populations. Such comparisons for 10:00-13:45 UT on August 12, 2000, 00:00-5:45 UT on June 2, 2001, and 13:00-16:45 on June 18, 2001 show a strong correlation between the location of the 8.5 keV trapped proton flux observed by MENA and the precipitating protons observed by FUV/SI12 but an anti-correlation between the 33 keV trapped protons observed by HENA and the FUV/SI12 observations. Possible explanations of these observations will also be presented.

Perez, J. D.; Zhang, X.; C:Son Brandt, P.; Mitchell, D. G.; Jahn, J.; Pollock, C. J.; Mende, S. B.

2003-12-01

32

Volume distribution of cerebrospinal fluid using multispectral MR imaging  

Microsoft Academic Search

The goal of this study was to design a reliable method to quantify and visualize the anatomical distribution of cerebrospinal fluid (CSF) intracranially. The method should be clinically applicable and based on multispectral analysis of three-dimensional (3D) magnetic resonance images. T1-weighted, T2-weighted and proton density-weighted fast 3D gradient pulse sequences were used to form high resolution multispectral 3D images of

Arvid Lundervold; Torfinn Taxt; Lars Ersland; Anne Marie Fenstad

2000-01-01

33

Cartilage imaging: motivation, techniques, current and future significance  

Microsoft Academic Search

Cartilage repair techniques and pharmacological therapies are currently areas of major clinical interest and research, in\\u000a particular to prevent and treat osteoarthritis. MR imaging-based techniques to visualize cartilage are prerequisites to guide\\u000a and monitor these therapies. In this review article, standard MR imaging sequences are described, including proton density-weighted\\u000a fast spin echo, spoiled gradient echo and dual echo steady state

Thomas M. Link; Robert Stahl; Klaus Woertler

2007-01-01

34

Proton chemical shift imaging, metabolic maps, and single voxel spectroscopy of glial brain tumors  

Microsoft Academic Search

Seventeen patients with presumed glial brain tumors were examined with proton chemical shift imaging and single voxel spectroscopy that used different echo times. Metabolite resonances were evaluated by metabolic ratios and absolutely by correcting for coil load and comparison to phantom measurements. Metabolic images were created to visualize the metabolic changes. All patients showed spectra that were different from those

Irina Mader; Werner Roser; Gisela Hagberg; Monika Schneider; Rolf Sauter; Joachim Seelig; Ernst W. Radue; Wolfgang Steinbrich I

1996-01-01

35

Morphology of the Cartilaginous Endplates in Human Intervertebral Disks with Ultrashort Echo Time MR Imaging  

PubMed Central

Purpose: To image human disk-bone specimens by using conventional spin-echo (SE) and ultrashort echo time (TE) techniques, to describe the morphology at magnetic resonance (MR) imaging, and to identify tissue components contributing to high signal intensity near the cartilaginous endplates (CEPs). Materials and Methods: This study was exempt from institutional review board approval, and informed consent was not required. Five cadaveric lumbar spines (mean age, 61 years ± 11) were prepared into six sample types containing different combinations of disk, uncalcified CEP, calcified CEP, and subchondral bone components and were imaged with proton density–weighted SE (repetition time msec/TE msec, 2000/15) and ultrashort TE (300/0.008, 6.6, echo-subtraction) sequences. Images were evaluated to determine the presence of intermediate-to-high signal intensity in regions excluding the bone marrow. Logistic regression was used to determine which tissue components were significant predictors of the presence of signal intensity for each MR technique. Results: On ultrashort TE MR images, intact disk/uncalcified CEP/calcified CEP/bone samples exhibited bilaminar intermediate-to-high signal intensity in the region near the CEP, consistent with the histologic appearance of uncalcified and calcified CEPs. Conversely, proton density–weighted SE images exhibited low signal intensity in this region. Results of logistic regression suggested that the presence of uncalcified CEP (P = .023) and calcified CEP (P = .007) in the sample were strong predictors of the presence of signal intensity on ultrashort TE images, whereas the disk was the only predictor (P < .001) of signal intensity on proton density–weighted SE images. Conclusion: Ultrashort TE imaging, unlike proton density–weighted SE imaging, enabled direct visualization of the uncalcified and calcified CEP. Evaluation of the morphology and identification of sources of signal intensity at ultrashort TE MR imaging provides opportunities to potentially aid in the understanding of degenerative disk disease. © RSNA, 2012

Statum, Sheronda; Zhang, Zhao; Yamaguchi, Tomonori; Wolfson, Tanya; Gamst, Anthony C.; Du, Jiang; Bydder, Graeme M.; Masuda, Koichi; Chung, Christine B.

2013-01-01

36

Midcourse space experiment\\/ultraviolet and visible imaging and spectrographic imaging limb observations of combined proton\\/hydrogen\\/electron aurora  

Microsoft Academic Search

Simultaneous measurements of auroral limb H Lyman alpha, H Balmer alpha, H Balmer beta, N2+ 1 NG 391.4-nm, and N2 2 PG 337.1-nm emissions excited by combined proton\\/hydrogen\\/electron precipitation are reported. The data were recorded by the Ultraviolet and Visible Imaging and Spectrographic Imaging (UVISI) spectrographic imagers on the Midcourse Space Experiment (MSX) satellite on November 10, 1996, while viewing

D. J. Strickland; J. Bishop; J. S. Evans; T. Majeed; R. J. Cox; D. Morrison; G. J. Romick; J. F. Carbary; L. J. Paxton; C.-I. Meng

2001-01-01

37

Imaging of Endogenous Exchangeable Proton Signals in the Human Brain Using Frequency Labeled Exchange (FLEX) Transfer Imaging  

PubMed Central

Purpose To image endogenous exchangeable proton signals in the human brain using a recently reported method called frequency labeled exchange transfer (FLEX) MRI. Methods As opposed to labeling exchangeable protons using saturation (i.e., chemical exchange saturation transfer, or CEST), FLEX labels exchangeable protons with their chemical shift evolution. The use of short high-power frequency pulses allows more efficient labeling of rapidly exchanging protons, while time domain acquisition allows removal of contamination from semi-solid magnetization transfer effects. Results FLEX-based exchangeable proton signals were detected in human brain over the 1–5 ppm frequency range from water. Conventional magnetization transfer contrast (MTC) and the bulk water signal did not interfere in the FLEX spectrum. The information content of these signals differed from in vivo CEST data in that the average exchange rate of these signals was 350–400 s?1, much faster than the amide signal usually detected using direct saturation (~30 s?1). Similarly, fast exchanging protons could be detected in egg white in the same frequency range where amide and amine protons of mobile proteins and peptides are known to resonate. Conclusions FLEX MRI in the human brain preferentially detects more rapidly exchanging amide/amine protons compared to traditional CEST experiments, thereby changing the information content of the exchangeable proton spectrum. This has the potential to open up different types of endogenous applications as well as more easy detection of rapidly exchanging protons in diaCEST agents or fast exchanging units such as water molecules in paracest agents without interference of conventional MTC.

Yadav, Nirbhay N.; Jones, Craig K.; Hua, Jun; Xu, Jiadi; van Zijl, Peter C. M.

2013-01-01

38

Transverse Imaging of the Proton in Exclusive Diffractive pp Scattering  

SciTech Connect

In a forthcoming paper we describe a new approach to rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, Higgs, etc.) in exclusive double-gap diffractive pp scattering, pp -> p + H + p. It is based on the idea that hard and soft interactions are approximately independent (QCD factorization), and allows us to calculate the RGS probability in a model-independent way in terms of the gluon generalized parton distributions (GPDs) in the colliding protons and the pp elastic scattering amplitude. Here we focus on the transverse momentum dependence of the cross section. By measuring the ''diffraction pattern'', one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton from the data.

Christian Weiss; Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman

2006-04-20

39

Gamma electron vertex imaging and application to beam range verification in proton therapy  

SciTech Connect

Purpose: This paper describes a new gamma-ray imaging method, ''gamma electron vertex imaging (GEVI)'', which can be used for precise beam range verification in proton therapy. Methods: In GEVI imaging, the high-energy gammas from a source or nuclear interactions are first converted, by Compton scattering, to electrons, which subsequently are traced by hodoscopes to determine the location of the gamma source or the vertices of the nuclear interactions. The performance of GEVI imaging for use in-beam range verification was evaluated by Monte Carlo simulations employing geant4 equipped with the QGSP{sub B}IC{sub H}P physics package. Results: Our simulation results show that GEVI imaging can determine the proton beam range very accurately, within 2-3 mm of error, even without any sophisticated analysis. The results were obtained under simplified conditions of monoenergetic pencil beams stopped in a homogeneous phantom and on the basis of the obtained results it is expected to achieve submillimeter accuracy in proton beam range measurement. Conclusions: If future experimental work confirms the simulated results presented in this paper, the use of GEVI imaging is expected to have a great potential in increasing the accuracy of proton beam range verification in a patient, resulting in significant improvement of treatment effectiveness by enabling tight conformation of radiation dose to the tumor volume and patient safety.

Hyeong Kim, Chan; Hyung Park, Jin; Seo, Hee; Rim Lee, Han [Department of Nuclear Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2012-02-15

40

Initial in vivo Rodent Sodium and Proton MR Imaging at 21.1 T  

PubMed Central

The first in vivo sodium and proton MR images and localized spectra of rodents were attained using the wide bore (105 mm) high resolution 21.1 T magnet, built and operated at the National High Magnetic Field Laboratory (Tallahassee, FL). Head images of normal mice (C57BL/6J) and Fisher rats (~ 250 g) were acquired with custom designed RF probes at frequencies of 237/900 MHz for sodium and proton, respectively. Sodium MRI resolutions of ~0.125 ?L for mouse and rat heads were achieved by using a 3D back-projection pulse sequence. A gain in SNR of ~ 3 for sodium and of ~ 2 times for proton were found relative to corresponding MR images acquired at 9.4 T. 3D FLASH proton mouse images (50×50×50 ?m3) were acquired in 90 min and corresponding rat images (100×100×100 ?m3) within a total time of 120 min. Both in vivo large rodent MR imaging and localized spectroscopy at the extremely high field of 21.1 T are feasible and demonstrate improved resolution and sensitivity valuable for structural and functional brain analysis.

Schepkin, Victor D.; Brey, William W.; Gor'kov, Peter L.; Grant, Samuel C.

2009-01-01

41

Imaging detector systems for soft x-ray and proton radiography  

NASA Astrophysics Data System (ADS)

Multi-pulse imaging systems have been developed for recording images from pulsed X-ray and proton radiographic sources. The number of successive images for x-ray radiography is limited to four being generated by 25 ns, pulsed sources in a close positioned geometry. The number of proton images are provided by the number of proton bursts (approximately 60 ns) delivered to the radiographic system. In both cases the radiation to light converter is a thin LSO crystal. The radiographic image formed is relayed by a direct, coherent bundle or lens coupling to a variety of electronic shuttered, cooled CCD cameras. The X-ray system is optimized for detecting bremmstrahlung, reflection geometry generated X-rays with end point energies below 300 keV. This has resulted in less than 200 ?m thick LSO converters which are 25 x 25 mm2. The converter is attached to a UV transmitting fiberoptic which in turn is directly coupled to a coherent bundle. The image is relayed to a 25 mm microchannel plate image intensifier attached to a 4 image framing camera. The framing camera image is recorded by a 1600 x 1600 pixel, cooled CCD camera. The current proton radiography imaging system for dynamic experiments is based on a system of seven individual high-resolution CCD cameras, each with its own optical relay and fast shuttering. The image of the radiographed object is formed on a 1.7 mm thick tiles of LSO scintillator. The rapid shuttering for each of the CCD's is accomplished via proximity-focussed planar diodes (PPD), which require application of 300-to-500 ns long, 12 kV pulses to the PPD from a dedicated HV pulser. The diodes are fiber-optically coupled to the front face of the CCD chips. For each time-frame a separate CCD assembly is required. The detection quantum efficiency (DQE) of the system is about 0.4. This is due to the lens coupling inefficiency, the necessary demagnification (typically between 5:1 and 3:1) in the system optics, and the planar-diode photo-cathode quantum efficiency (QE) (of approximately 15%). More recently, we have incorporated a series of 4 or 9 image framing cameras to provide an increased number of images. These have been coupled to cooled CCD cameras as readouts. A detailed description of the x-ray and proton radiographic imaging systems are discussed as well as observed limitations in performance. A number of improvements are also being developed which will be described.

King, Nicholas S. P.; Baker, Stuart A.; Jaramillo, Steven A.; Kwiatkowski, Kris; Lutz, Stephen S.; Hogan, Gary E.; Holmes, Vanner H.; Morris, Christopher L.; Nedrow, Paul T.; Pazuchanics, Peter D.; Rohrer, John S.; Sorenson, Dan S.; Thompson, Richard T.

2003-07-01

42

7 Tesla imaging of cerebral radiation necrosis after arteriovenous malformations treatment using amide proton transfer (APT) imaging.  

PubMed

Arteriovenous malformations (AVM) can be treated with stereotactic radiosurgery. An infrequent, but important complication of this treatment is radionecrosis, which can be detected by MRI. However, the imaging characteristics of necrosis are unspecific in conventional MRI. Here, we report a case of necrosis after radiotherapy of an AVM to illustrate the potential of 7 Tesla MRI including amide proton transfer (APT) for necrosis imaging. PMID:22246564

Gerigk, Lars; Schmitt, Benjamin; Stieltjes, Bram; Röder, Falk; Essig, Marco; Bock, Michael; Schlemmer, Heinz-Peter; Röthke, Matthias

2012-05-01

43

Can proton radiography be used to image imploding target in ICF experiments?  

NASA Astrophysics Data System (ADS)

Generation of high intensity and well collimated multi energetic proton beams from laser-matter interaction extend the possibility to use protons as a diagnostic to image imploding target in Inertial Confinement Fusion experiments. An experiment was done at the Rutherford Appleton Laboratory (Vulcan Laser Petawatt laser) to study fast electron propagation in cylindrically compressed targets, a subject of interest for fast ignition. This was performed in the framework of the experimental road map of HiPER (the European High Power laser Energy Research facility Project). In the experiment, protons accelerated by a ps-laser pulse were used to radiograph a 220 m diameter cylinder (20 m wall, filled with low density foam), imploded with 200 J of green laser light in 4 symmetrically incident beams of pulse length 1 ns. Point projection proton backlighting was used to get the compression history and the stagnation time. Detailed comparison with 2D numerical hydro simulations has been done using a Monte Carlo code adapted to describe multiple scattering and plasma effects and with those from hard X-ray radiography. These analysis shows that due to the very large mass densities reached during implosion processes, protons traveling through the target undergo a very large number of collisions which deviate protons from their original trajectory reducing proton radiography resolution. Here we present a simple analytical model to study the proton radiography diagnostic performance as a function of the main experimental parameters such as proton beam energy and target areal density. This approach leads to define two different criteria for PR resolution (called "strong" and "weak" condition) describing different experimental conditions. Finally numerical simulations using both hydrodynamic and Monte Carlo codes are presented to validate analytical predictions.

Volpe, L.; Batani, D.; Vauzour, B.; Nicolai, Ph.; Santos, J. J.; Dorchies, F.; Fourment, C.; Hulin, S.; Regan, C.; Perez, F.; Baton, S.; Koenig, M.; Lancaster, K.; Galimberti, M.; Heathcote, R.; Tolley, M.; Spindloe, Ch.; Koester, P.; Labate, L.; Gizzi, L. A.; Benedetti, C.; Sgattoni, A.; Richetta, M.

2011-05-01

44

Proton magnetic resonance spectroscopic imaging of human breast cancer: A preliminary study  

Microsoft Academic Search

Purpose: To investigate the diagnostic value of proton mag- netic resonance spectroscopic imaging (MRSI) in patients with breast lesions. Materials and Methods: Eighteen patients underwent breast MRSI and MRI at 1.5 T. Contrast-enhanced MR was used to identify the lesion, after which single-slice MRSI (TR\\/ TE 2000\\/272 msec, 10-mm slice thickness) was per- formed. Water, lipid, and choline (Cho) images

Michael A. Jacobs; Peter B. Barker; Paul A. Bottomley; Zaver Bhujwalla; David A. Bluemke

2004-01-01

45

Proton electron double resonance imaging (PEDRI) of the isolated beating rat heart.  

PubMed

Proton electron double resonance imaging (PEDRI) is a double resonance technique where proton MRI is performed with irradiation of a paramagnetic solute. A low-field PEDRI system was developed at 20.1 mT suitable for imaging free radicals in biological samples. With a new small dual resonator, PEDRI was applied to image nitroxide free radicals in isolated beating rat hearts. Experiments with phantoms showed maximum image enhancement factors (IEF) of 42 or 28 with TEMPONE radical concentrations of 2-3 mM at EPR irradiation powers of 12W or 6W, respectively. In the latter case, image resolution better than 0.5 mm and radical sensitivity of 5 microM was obtained. For isolated heart studies, EPR irradiation power of 6W provided optimal compromise of modest sample heating with good SNR. Only a small increase in temperature of about 1 degrees C was observed, while cardiac function remained within 10% of control values. With infusion of 3 mM TEMPONE an IEF of 15 was observed enabling 2D or 3D images to be obtained in 27 sec or 4.5 min, respectively. These images visualized the change in radical distribution within the heart during infusion and clearance. Thus, PEDRI enables rapid and high-quality imaging of free radical uptake and clearance in perfused hearts and provides a useful technique for studying cardiac radical metabolism. PMID:12876716

Liebgott, Thibaut; Li, Haihong; Deng, Yuanmu; Zweier, Jay L

2003-08-01

46

Experimental Study of Calculated t1 Images Under Flow Conditions Using Protons and FLUORINE-19 in Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

A gradient refocused echo (GRE) pulse protocol has been developed and implemented to obtain calculated T1 images under flow conditions. This sequence acquires multiple images with different flip angles and uses a least -square fit to obtain calculated T1 images. A theoretical analysis of imprecision in the calculated T1 images is discussed. In accordance with Wang (49), the optimal parameters as determined by computer simulation were found to be 20 ^circ and 100^ circ for the flip angles in a two point fit for TR falling in the range 0.3 to 1.0 T1. Flow compensation was added to the pulse sequence for imaging flow phantoms containing GD-DTPA doped water and perfluorocarbon (PFC) compounds for a range of flow rates (0-55 cm/s). Flow compensation was found to effectively recover signal loss due to flow related dephasing. Experimental testing of this protocol has been performed on stationary proton and PFC compound phantoms utilizing ^1H and ^{19}F magnetic resonance imaging respectively. There is good agreement between the experimental results and the theoretical predictions about imprecision in the calculated T1 images. Analysis of variance of the mean T1 values of the calculated T1 images of the proton and PFC flow phantoms indicated that for the flow phantom geometry used in this study, there was no statistical difference among these mean T1 values from flow phantoms with different flow rates (including stationary status). It is believed that this protocol may provide an imaging method for mapping the pO _2 distribution in the vascular space in vivo utilizing perfluorocarbon compounds and ^ {19}F magnetic resonance imaging.

Zheng, Jie

47

Three-dimensional imaging of aerosol particles with scanning proton microprobe in a confocal arrangement  

SciTech Connect

We have reconstructed three-dimensional (3D) element-specific distributions of aerosol microparticles captured in a thick quartz filter. The characteristic x rays were induced by a proton microprobe and detected by a Si(Li) spectrometer equipped with a polycapillary lens. Combining a fine microbeam scanning in the lateral plane with the sample movement parallel to the beam axis, the aerosol particles were driven across the sensitive microvolume and for Fe, Ca, S, and Si a sequence of two-dimensional lateral x-ray images was recorded. This is the first example of an x-ray element selective 3D imaging of a few micrometer sized objects with a proton beam.

Zitnik, M.; Pelicon, P. [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Grlj, N. [Primorska Institute for Natural Science and Technology, Muzejski trg 2, SI-6000 Koper (Slovenia); Karydas, A. G.; Sokaras, D. [Institute of Nuclear Physics, NCSR 'Demokritos', GR-15310 Athens (Greece); Schuetz, R.; Kanngiesser, B. [Institute of Optics and Atomic Physics, Technical University of Berlin, D-10623 Berlin (Germany)

2008-09-01

48

The rapid secondary electron imaging system of the proton beam writer at CIBA  

NASA Astrophysics Data System (ADS)

The recent years have witnessed a proliferation of research involving proton beam (p-beam) writing. This has prompted investigations into means of optimizing the process of p-beam writing so as to make it less time consuming and more efficient. One such avenue is the improvement of the pre-writing preparatory procedures that involves beam focusing and sample alignment which is centred on acquiring images of a resolution standard or sample. The conventional mode of imaging used up to now has utilized conventional nuclear microprobe signals that are of a pulsed nature and are inherently slow. In this work, we report the new imaging system that has been introduced, which uses proton induced secondary electrons. This in conjunction with software developed in-house that uses a National Instruments DAQ card with hardware triggering, facilitates large data transfer rates enabling rapid imaging. Frame rates as much as 10 frames/s have been achieved at an imaging resolution of 512 × 512 pixels.

Udalagama, C. N. B.; Bettiol, A. A.; van Kan, J. A.; Teo, E. J.; Watt, F.

2007-07-01

49

Magnetic resonance imaging of the Amine-Proton EXchange (APEX) dependent contrast  

PubMed Central

Chemical exchange between water and labile protons from amino-acids, proteins and other molecules can be exploited to provide tissue contrast with magnetic resonance imaging (MRI) techniques. Using an off-resonance Spin-Locking (SL) scheme for signal preparation is advantageous because the image contrast can be tuned to specific exchange rates by adjusting SL pulse parameters. While the amide-proton transfer (APT) contrast is obtained optimally with steady-state preparation, using a low power and long irradiation pulse, image contrast from the faster amine-water proton exchange (APEX) is optimized in the transient state with a higher power and a shorter SL pulse. Our phantom experiments show that the APEX contrast is sensitive to protein and amino acid concentration, as well as pH. In vivo 9.4-T SL MRI data of rat brains with irradiation parameters optimized to slow exchange rates have a sharp peak at 3.5 ppm and also broad peak at ?2 to ?5 ppm, inducing negative contrast in APT-weighted images, while the APEX image has large positive signal resulting from a weighted summation of many different amine-groups. Brain ischemia induced by cardiac arrest decreases pure APT signal from ~1.7% to ~0%, and increases the APEX signal from ~8% to ~16%. In the middle cerebral artery occlusion (MCAO) model, the APEX signal shows different spatial and temporal patterns with large inter-animal variations compared to APT and water diffusion maps. Because of the similarity between the chemical exchange saturation transfer (CEST) and SL techniques, APEX contrast can also be obtained by a CEST approach using similar irradiation parameters. APEX may provide useful information for many diseases involving a change in levels of proteins, peptides, amino-acids, or pH, and may serve as a sensitive neuroimaging biomarker.

Jin, Tao; Wang, Ping; Zong, Xiaopeng; Kim, Seong-Gi

2011-01-01

50

Major Solar Proton Event during September 24-30, 2001 using Imaging Riometer Technique (P42)  

NASA Astrophysics Data System (ADS)

sharma_ashokkumar@yahoo.com Major outbursts of mass and energy i.e. a fast full halo CME with speed of 2402 km/sec from region 9632, located on the Sun at S16 E23 was observed at 1030 UT by SOHO/LASCO C3 coronagraph on September 24, 2001. The proton event at greater than 100 MeV began at 1440 UT on 24 September, reached a maximum of 31.2 PFU at 0755 UT on 25 September and ended at 1940 UT on 26 September 2001. The protons event at greater than 10 MeV began at 1215 UT on 24 September, reached a maximum of 12,900 PFU at 2235 UT on 25 September and ended at 1710 UT on 30 September 2001. These extremely high energetic protons accelerated during CMEs produces significant ionization in the D region of the ionosphere at high latitudes. Increase in ionization in the D region causes cosmic noise absorption. The major Polar Cap Absorption (PCA) observed during SEPTEMBER 24 -30, 2001 will be discussed in this paper. Imaging riometer observations were made from Kilpisjarvi (69.05oN; 20.79oW), Northern Finland during the PCA event. For this the remote and insitu data have been used. The imaging riometer for ionospheric studies (IRIS) is used to quantify the intensity, time of occurrence and location of CME effects on the ionosphere.

Sharma, A. K.; Vhatkar, R. S.

2006-11-01

51

In vivo Proton Electron Double Resonance Imaging of Mice with Fast Spin Echo Pulse Sequence  

PubMed Central

Purpose To develop and evaluate a 2D fast spin echo (FSE) pulse sequence for enhancing temporal resolution and reducing tissue heating for in vivo proton electron double resonance imaging (PEDRI) of mice. Materials and Methods A four-compartment phantom containing 2 mM TEMPONE was imaged at 20.1 mT using 2D FSE-PEDRI and regular gradient echo (GRE)-PEDRI pulse sequences. Control mice were infused with TEMPONE over ?1 min followed by time-course imaging using the 2D FSE-PEDRI sequence at intervals of 10 – 30 s between image acquisitions. The average signal intensity from the time-course images was analyzed using a first-order kinetics model. Results Phantom experiments demonstrated that EPR power deposition can be greatly reduced using the FSE-PEDRI pulse sequence compared to the conventional gradient echo pulse sequence. High temporal resolution was achieved at ?4 s per image acquisition using the FSE-PEDRI sequence with a good image SNR in the range of 233-266 in the phantom study. The TEMPONE half-life measured in vivo was ?72 s. Conclusion Thus, the FSE-PEDRI pulse sequence enables fast in vivo functional imaging of free radical probes in small animals greatly reducing EPR irradiation time with decreased power deposition and provides increased temporal resolution.

Sun, Ziqi; Li, Haihong; Petryakov, Sergey; Samouilov, Alex; Zweier, Jay L.

2011-01-01

52

Studying the Burn Region in ICF Implosions with Proton Emission Imaging  

NASA Astrophysics Data System (ADS)

Proton core imaging spectroscopy (PCIS) is being used to study the effects of fuel shell mix in implosions of D^3He-filled capsules at OMEGA. Penumbral imaging of fusion products is used to obtain the size and shape of the nuclear burn region. Experimental differences in the D^3He burn region will be explored for varying laser conditions and for different shell types (2 to 3 mm glass and 17, 20, 24 and 27 mm CH). Secondary D^3He proton production profiles from a D_2-filled-capsule implosion will be examined to explore the feasibility of imaging cryogenic implosions. Measured burn profiles will be compared to predictions of clean 1-D simulations and to x-ray images. This work was supported in part by the U.S. Department of Energy (DE-FG03-03SF22691, DE-FG03-03NA00058, and Cooperative Agreement DE-FC52-92SF19460), LLE (412160-001G), and LLNL (B504974).

Deciantis, J. L.; Seguin, F. H.; Frenje, J. A.; Rygg, J. R.; Chen, C. D.; Li, C. K.; Petrasso, R. D.; Delettrez, J. A.; Knauer, J. P.; Marshall, F. J.; Meyerhofer, D. D.; Roberts, S.; Sangster, T. C.; Smalyuk, V. A.

2004-11-01

53

Imaging the Proton Concentration and Mapping the Spatial Distribution of the Electric Field of Catalytic Micropumps  

NASA Astrophysics Data System (ADS)

Catalytic engines can use hydrogen peroxide as a chemical fuel in order to drive motion at the microscale. The chemo-mechanical actuation is a complex mechanism based on the interrelation between catalytic reactions and electro-hydrodynamics phenomena. We studied catalytic micropumps using fluorescence confocal microscopy to image the concentration of protons in the liquid. In addition, we measured the motion of particles with different charges in order to map the spatial distributions of the electric field, the electrostatic potential and the fluid flow. The combination of these two techniques allows us to contrast the gradient of the concentration of protons against the spatial variation in the electric field. We present numerical simulations that reproduce the experimental results. Our work sheds light on the interrelation between the different processes at work in the chemomechanical actuation of catalytic pumps. Our experimental approach could be used to study other electrochemical systems with heterogeneous electrodes.

Farniya, A. Afshar; Esplandiu, M. J.; Reguera, D.; Bachtold, A.

2013-10-01

54

Dayside Proton Aurora: Comparisons between Global MHD Simulations and Image Observations  

NASA Technical Reports Server (NTRS)

The IMAGE mission provides a unique opportunity to evaluate the accuracy of current global models of the solar wind interaction with the Earth's magnetosphere. In particular, images of proton auroras from the Far Ultraviolet Instrument (FUV) onboard the IMAGE spacecraft are well suited to support investigations of the response of the Earth's magnetosphere to interplanetary disturbances. Accordingly, we have modeled two events that occurred on June 8 and July 28, 2000, using plasma and magnetic field parameters measured upstream of the bow shock as input to three-dimensional magnetohydrodynamic (MHD) simulations. This paper begins with a discussion of images of proton auroras from the FUV SI-12 instrument in comparison with the simulation results. The comparison showed a very good agreement between intensifications in the auroral emissions measured by FUV SI-12 and the enhancement of plasma flows into the dayside ionosphere predicted by the global simulations. Subsequently, the IMAGE observations are analyzed in the context of the dayside magnetosphere's topological changes in magnetic field and plasma flows inferred from the simulation results. Finding include that the global dynamics of the auroral proton precipitation patterns observed by IMAGE are consistent with magnetic field reconnection occurring as a continuous process while the iMF changes in direction and the solar wind dynamic pressure varies. The global simulations also indicate that some of the transient patterns observed by IMAGE are consistent with sporadic reconnection processes. Global merging patterns found in the simulations agree with the antiparallel merging model. though locally component merging might broaden the merging region, especially in the region where shocked solar wind discontinuities first reach the magnetopause. Finally, the simulations predict the accretion of plasma near the bow shock in the regions threaded by newly open field lines on which plasma flows into the dayside ionosphere are enhanced. Overall the results of these initial comparisons between global MHD simulation results and IMAGE observations emphasize the interplay between reconnection and dynamic pressure processes at the dayside magnetopause. as well as the intricate connection between the bow shock and the auroral region.

Berchem, J.; Fuselier, S. A.; Petrinec, S.; Frey, H. U.; Burch, J. L.

2003-01-01

55

Displacement Damage Effects Due to Neutron and Proton Irradiations on CMOS Image Sensors Manufactured in Deep Submicron Technology  

Microsoft Academic Search

Displacement damage effects due to proton and neutron irradiations of CMOS image sensors dedicated to imaging are presented through the analysis of the dark current behavior in pixel arrays and isolated photodiodes. The mean dark current increase and the dark current nonuniformity are investigated. Dark current histogram observations are compared to damage energy distributions based on GEANT 4 calculations. We

Cedric Virmontois; Vincent Goiffon; Pierre Magnan; Sylvain Girard; Christophe Inguimbert; Sophie Petit; Guy Rolland; Olivier Saint-Pé

2010-01-01

56

Simulation of the longitudinal splitting of the nightside proton aurora during a substorm seen by the IMAGE spacecraft  

NASA Astrophysics Data System (ADS)

We use the OpenGGCM global MHD code to model the magnetosphere during substorms using input from solar wind monitors. Using the MHD fields and assuming a full loss cone, we calculate the precipitation from protons scattered by fieldline curvature during a substorm seen by the IMAGE spacecraft on April 28, 2001. During the substorm, the proton aurora splits in local time shortly after onset. The simulation reproduces the observed splitting and shows that it is caused by the local time expansion of the substorm current wedge. We also examine the relationships between the simulated proton and electron precipitation.

Gilson, M. L.; Raeder, J.; Donovan, E. F.; Mende, S. B.; Ge, Y.

2010-12-01

57

Initial far-field otr images generated by 120-GeV protons at FNAL.  

SciTech Connect

We have successfully imaged for the first time the angular distribution patterns of optical transition radiation (OTR) generated by 120-GeV proton beams passing through an Al metal plane. These experiments were performed at Fermilab (FNAL) with the same chamber, foil, and camera design as with the near-field experiments previously reported. In this case the lens-to-CID-chip separation was remotely adjusted to provide the focus-at- infinity, or far-field optical imaging. Data have been obtained in transport lines both before the antiproton production target and before the NuMI target with particle intensities of about 5 to 22 times 10{sup 12}. A two-foil interferometer calculation was also performed. Single-foil experimental and modeling results will be presented.

Lumpkin, A. H.; Scarpine, V. E.; Tassotto, G. R.; High Energy Physics; FNAL

2008-01-01

58

Image mosaic method for recognition of proton track in nuclear emulsions  

NASA Astrophysics Data System (ADS)

The recognition of the tracks in a nuclear emulsion is usually completed by a microscope system. However, the area of the field of view (FOV) of the microscope system is very small for the recognition of the entire proton-recoil tracks in nuclear emulsions. We have to stitch the images observed in several FOVs to obtain a large region including all entire tracks. Unfortunately, the hysteresis errors and the vibrations of the microscope stage will cause uncertainties in the relative locations between the adjacent FOVs, which will seriously affect the track recognition. In this paper, we propose an image mosaic method based on an improved ratio template matching algorithm, so as to accurately obtain the relative locations between the adjacent FOVs. The method can effectively suppress the position errors caused by the hysteresis error and the vibration from more than 10 ?m to about 0.5 ?m.

Ruan, Jin-lu; Li, Hong-yun; Zhang, Jian-fu; Zhang, Zhong-bing; Chen, Liang; Song, Ji-wen; Liu, Jin-liang; Liu, Jun

2014-10-01

59

Hydrodynamic proton beam-target interaction experiments using an improved line-imaging velocimeter  

SciTech Connect

The hydrodynamic response of 10- to 100-{mu}m-thick target foils exposed to a high-power proton beam is investigated by laser Doppler velocimetry of the rear surface. For the first time, the ablative acceleration and the ablation pressure have been measured spatially resolved by use of an improved line imaging velocimeter. The instrument was operated in both the VISAR and the ORVIS mode, and takes advantage of the spatial localization of the interference fringes in the mirror planes for an intermediate imaging. This allows us to obtain optimum contrast, high spatial resolution of {le}10{mu}m, and to vary the magnification in a wide range. {copyright} {ital 1996 American Institute of Physics.}

Baumung, K.; Singer, J. [Forschungszentrum Karlsruhe, P.O. Box 3640, D-76021 Karlsruhe (Germany); Razorenov, S.V.; Utkin, A.V. [Russian Academy of Sciences, Institute of Chemical Physics (Chernogolovka), Chernogolovka, 142432 (Russia)

1996-05-01

60

A study of radiation effects of 9 and 12 MeV protons on Chinese CMOS image sensor degradation  

Microsoft Academic Search

The 9 and 12 MeV proton irradiations of the Chinese CMOS Image Sensor in the fluence range from 1×109 to 4×1010 cm-2 and 1×109 to 2×1012 cm-2 have been carried out respectively. The color pictures and dark output images are captured, and the average brightness of dark output images is calculated. The anti-irradiation fluence thresholds for 9 and 12 MeV

Xiang-Ti Meng; Qiang Huang; Yan-Xiu Ma; Yong-Nan Zheng; Ping Fan; Sheng-Yun Zhu

2008-01-01

61

Can Proton MR Spectroscopic and Perfusion Imaging Differentiate Between Neoplastic and Nonneoplastic Brain Lesions in Adults?  

PubMed Central

BACKGROUND AND PURPOSE Noninvasive diagnosis of brain lesions is important for the correct choice of treatment. Our aims were to investigate whether 1) proton MR spectroscopic imaging (1H-MRSI) can aid in differentiating between tumors and nonneoplastic brain lesions, and 2) perfusion MR imaging can improve the classification. MATERIALS AND METHODS We retrospectively examined 69 adults with untreated primary brain lesions (brain tumors, n = 36; benign lesions, n = 10; stroke, n = 4; demyelination, n = 10; and stable lesions not confirmed on pathologic examination, n = 9). MR imaging and 1H-MRSI were performed at 1.5T before biopsy or treatment. Concentrations of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the lesion were expressed as metabolite ratios and were normalized to the contralateral hemisphere. Dynamic susceptibility contrast-enhanced perfusion MR imaging was performed in a subset of patients (n = 32); relative cerebral blood volume (rCBV) was evaluated. Discriminant function analysis was used to identify variables that can predict inclusion in the neoplastic or nonneoplastic lesion groups. Receiver operator characteristic (ROC) analysis was used to compare the discriminatory capability of 1H-MRSI and perfusion MR imaging. RESULTS The discriminant function analysis correctly classified 84.2% of original grouped cases (P < .0001), on the basis of NAA/Cho, Chonorm, NAAnorm, and NAA/Cr ratios. MRSI and perfusion MR imaging had similar discriminatory capabilities in differentiating tumors from nonneoplastic lesions. With cutoff points of NAA/Cho ?0.61 and rCBV ?1.50 (corresponding to diagnosis of the tumors), a sensitivity of 72.2% and specificity of 91.7% in differentiating tumors from nonneoplastic lesions were achieved. CONCLUSION These results suggest a promising role for 1H-MRSI and perfusion MR imaging in the distinction between brain tumors and nonneoplastic lesions in adults.

Hourani, R.; Brant, L.J.; Rizk, T.; Weingart, J.D.; Barker, P.B.; Horska, A.

2010-01-01

62

Sensitivity study of proton radiography and comparison with kV and MV x-ray imaging using GEANT4 Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

The imaging sensitivity of proton radiography has been studied and compared with kV and MV x-ray imaging using Monte Carlo simulations. A phantom was specifically modeled using 21 different material inserts with densities ranging from 0.001 to 1.92 g cm-3. These simulations were run using the MGH double scattered proton beam, scanned pencil proton beams from 200 to 490 MeV, as well as pure 50 keV, 100 keV, 1 MeV and 2 MeV gamma x-ray beams. In order to compare the physics implied in both proton and photon radiography without being biased by the current state of the art in detector technology, the detectors were considered perfect. Along with spatial resolution, the contrast-to-noise ratio was evaluated and compared for each material. These analyses were performed using radiographic images that took into account the following: only primary protons, both primary and secondary protons, and both contributions while performing angular and energetic cuts. Additionally, tissue-to-tissue contrasts in an actual lung cancer patient case were studied for simulated proton radiographs and compared against the original kV x-ray image which corresponds to the current patient set-up image in the proton clinic. This study highlights the poorer spatial resolution of protons versus x-rays for radiographic imaging purposes, and the excellent density resolution of proton radiography. Contrasts around the tumor are higher using protons in a lung cancer patient case. The high-density resolution of proton radiography is of great importance for specific tumor diagnostics, such as in lung cancer, where x-ray radiography operates poorly. Furthermore, the use of daily proton radiography prior to proton therapy would ameliorate patient set-up while reducing the absorbed dose delivered through imaging.

Depauw, Nicolas; Seco, Joao

2011-04-01

63

STANDARD-BASED METHOD FOR PROTON-ELECTRON DOUBLE RESONANCE IMAGING OF OXYGEN  

PubMed Central

Proton-electron double resonance imaging (PEDRI) has been utilized for indirect determination of oxygen concentrations in aqueous samples and living systems. Due to the complexity of the problem, there are seven oxygen related parameters that need to be measured to determine the distribution of oxygen. We present an improved approach in which image intensities from only two PEDRI acquisitions with different EPR irradiation powers are required to determine the distribution of a paramagnetic probe and oxygen in an analyzed sample. This is achieved using three reference samples with known concentrations of a paramagnetic probe and oxygen placed inside the resonator together with the measurement sample. An EPR-off image, which has low signal intensity at low magnetic field (0.02 T) is not required for the calculations, significantly reducing the total time of the experiments and the noise while enhancing the accuracy of these oxygen measurements. The Finland trityl radical was used as the paramagnetic probe and oxygen concentrations could be accurately measured and imaged over the physiological range from 0 to 240 µM.

Efimova, Olga V.; Caia, George L.; Sun, Ziqi; Petryakov, Sergey; Kesselring, Eric; Samouilov, Alexandre; Zweier, Jay L.

2011-01-01

64

In-beam PET imaging for on-line adaptive proton therapy: an initial phantom study.  

PubMed

We developed and investigated a positron emission tomography (PET) system for use with on-line (both in-beam and intra-fraction) image-guided adaptive proton therapy applications. The PET has dual rotating depth-of-interaction measurable detector panels by using solid-state photomultiplier (SSPM) arrays and LYSO scintillators. It has a 44 mm diameter trans-axial and 30 mm axial field-of-view (FOV). A 38 mm diameter polymethyl methacrylate phantom was placed inside the FOV. Both PET and phantom axes were aligned with a collimated 179.2 MeV beam. Each beam delivered ?50 spills (0.5 s spill and 1.5 s inter-spill time, 3.8 Gy at Bragg peak). Data from each beam were acquired with detectors at a given angle. Nine datasets for nine beams with detectors at nine different angles over 180° were acquired for full-tomographic imaging. Each dataset included data both during and 5 min after irradiations. The positron activity-range was measured from the PET image reconstructed from all nine datasets and compared to the results from simulated images. A (22)Na disc-source was also imaged after each beam to monitor the PET system's performance. PET performed well except for slight shifts of energy photo-peak positions (<1%) after each beam, due mainly to the neutron exposure of SSPM that increased the dark-count noise. This minor effect was corrected offline with a shifting 350-650 keV energy window for each dataset. The results show a fast converging of activity-ranges measured by the prototype PET with high sensitivity and uniform resolution. Sub-mm activity-ranges were achieved with minimal 6 s acquisition time and three spill irradiations. These results indicate the feasibility of PET for intra-fraction beam-range verification. Further studies are needed to develop and apply a novel clinical PET system for on-line image-guided adaptive proton therapy. PMID:24874943

Shao, Yiping; Sun, Xishan; Lou, Kai; Zhu, Xiaorong R; Mirkovic, Dragon; Poenisch, Falk; Grosshans, David

2014-07-01

65

In-beam PET imaging for on-line adaptive proton therapy: an initial phantom study  

NASA Astrophysics Data System (ADS)

We developed and investigated a positron emission tomography (PET) system for use with on-line (both in-beam and intra-fraction) image-guided adaptive proton therapy applications. The PET has dual rotating depth-of-interaction measurable detector panels by using solid-state photomultiplier (SSPM) arrays and LYSO scintillators. It has a 44 mm diameter trans-axial and 30 mm axial field-of-view (FOV). A 38 mm diameter polymethyl methacrylate phantom was placed inside the FOV. Both PET and phantom axes were aligned with a collimated 179.2 MeV beam. Each beam delivered ?50 spills (0.5 s spill and 1.5 s inter-spill time, 3.8 Gy at Bragg peak). Data from each beam were acquired with detectors at a given angle. Nine datasets for nine beams with detectors at nine different angles over 180° were acquired for full-tomographic imaging. Each dataset included data both during and 5 min after irradiations. The positron activity-range was measured from the PET image reconstructed from all nine datasets and compared to the results from simulated images. A 22Na disc-source was also imaged after each beam to monitor the PET system's performance. PET performed well except for slight shifts of energy photo-peak positions (<1%) after each beam, due mainly to the neutron exposure of SSPM that increased the dark-count noise. This minor effect was corrected offline with a shifting 350–650 keV energy window for each dataset. The results show a fast converging of activity-ranges measured by the prototype PET with high sensitivity and uniform resolution. Sub-mm activity-ranges were achieved with minimal 6 s acquisition time and three spill irradiations. These results indicate the feasibility of PET for intra-fraction beam-range verification. Further studies are needed to develop and apply a novel clinical PET system for on-line image-guided adaptive proton therapy.

Shao, Yiping; Sun, Xishan; Lou, Kai; Zhu, Xiaorong R.; Mirkovic, Dragon; Poenisch, Falk; Grosshans, David

2014-07-01

66

Absolute calibration of photostimulable image plate detectors used as (0.5-20 MeV) high-energy proton detectors  

SciTech Connect

In this paper, the absolute calibration of photostimulable image plates (IPs) used as proton detectors is presented. The calibration is performed in a wide range of proton energies (0.5-20 MeV) by exposing simultaneously the IP and calibrated detectors (radiochromic films and solid state detector CR39) to a source of broadband laser-accelerated protons, which are spectrally resolved. The final result is a calibration curve that enables retrieving the proton number from the IP signal.

Mancic, A.; Fuchs, J.; Antici, P.; Audebert, P. [LULI, Ecole Polytechnique, UMR 7605, CNRS, CEA, UPMC, Route de Saclay, 91128 Palaiseau Cedex (France); Gaillard, S. A. [Physics Department, MS 220, University of Nevada, Reno, Nevada 89557 (United States)

2008-07-15

67

Design of a Nested Eight-Channel Sodium and Four-Channel Proton Coil for 7 Tesla Knee Imaging  

PubMed Central

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.

Brown, Ryan; Madelin, Guillaume; Lattanzi, Riccardo; Chang, Gregory; Regatte, Ravinder R.; Sodickson, Daniel K.; Wiggins, Graham C.

2012-01-01

68

Design of a nested eight-channel sodium and four-channel proton coil for 7T knee imaging.  

PubMed

The critical design aim for a sodium/proton coil is to maximize sodium sensitivity and transmit field homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils use lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7 T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio. 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 capabilities. Both additional modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium signal-to-noise ratio was 1.2-1.7 times greater in the developed eight-channel array than in a mononuclear sodium birdcage coil, whereas the developed four-channel proton array provided signal-to-noise ratio similar to that of a commercial mononuclear proton birdcage coil. PMID:22887123

Brown, Ryan; Madelin, Guillaume; Lattanzi, Riccardo; Chang, Gregory; Regatte, Ravinder R; Sodickson, Daniel K; Wiggins, Graham C

2013-07-01

69

Time-of-flight neutron rejection to improve prompt gamma imaging for proton range verification: a simulation study.  

PubMed

Therapeutic proton and heavier ion beams generate prompt gamma photons that may escape from the patient. In principle, this allows for real-time, in situ monitoring of the treatment delivery, in particular, the hadron range within the patient, by imaging the emitted prompt gamma rays. Unfortunately, the neutrons simultaneously created with the prompt photons create a background that may obscure the prompt gamma signal. To enhance the accuracy of proton dose verification by prompt gamma imaging, we therefore propose a time-of-flight (TOF) technique to reject this neutron background, involving a shifting time window to account for the propagation of the protons through the patient. Time-resolved Monte Carlo simulations of the generation and transport of prompt gamma photons and neutrons upon irradiation of a PMMA phantom with 100, 150 and 200 MeV protons were performed using Geant4 (version 9.2.p02) and MCNPX (version 2.7.D). The influence of angular collimation and TOF selection on the prompt gamma and neutron longitudinal profiles is studied. Furthermore, the implications of the proton beam microstructure (characterized by the proton bunch width and repetition period) are investigated. The application of a shifting TOF window having a width of ?TOF(z) = 1.0 ns appears to reduce the neutron background by more than 99%. Subsequent application of an energy threshold does not appear to sharpen the distal falloff of the prompt gamma profile but reduces the tail that is observed beyond the proton range. Investigations of the influence of the beam time structure show that TOF rejection of the neutron background is expected to be effective for typical therapeutic proton cyclotrons. PMID:22996154

Biegun, Aleksandra K; Seravalli, Enrica; Lopes, Patrícia Cambraia; Rinaldi, Ilaria; Pinto, Marco; Oxley, David C; Dendooven, Peter; Verhaegen, Frank; Parodi, Katia; Crespo, Paulo; Schaart, Dennis R

2012-10-21

70

Neurochemistry of Drug Action: Insights from Proton Magnetic Resonance Spectroscopic Imaging And Their Relevance to Addiction  

PubMed Central

Proton magnetic resonance spectroscopy (1H MRS) is a non-invasive imaging technique that permits measurement of particular compounds or metabolites within the tissue of interest. In the brain, 1H MRS provides a snapshot of the neurochemical environment within a defined volume of interest. A search of the literature demonstrates the widespread utility of this technique for characterizing tumors, tracking the progress of neurodegenerative disease, and for understanding the neurobiological basis of psychiatric disorders. As of relatively recently, 1H MRS has found its way into substance abuse research, and it is beginning to become recognized as a valuable complement in the brain imaging toolbox that also contains positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI). Drug abuse studies employing 1H MRS have identified a number biochemical changes in the brain. The most consistent alterations across drug class were reductions in N-acetylaspartate and elevations in myo-inositol, while changes in choline, creatine, and amino acid transmitters also were abundant. Together, the studies discussed herein provide evidence that drugs of abuse may have a profound impact on neuronal health, energy metabolism and maintenance, inflammatory processes, cell membrane turnover, and neurotransmission, and these biochemical changes may underlie the neuropathology within brain tissue that subsequently gives rise to the cognitive and behavioral impairments associated with drug addiction.

Licata, Stephanie C.; Renshaw, Perry F.

2011-01-01

71

Investigation of relativistic intensity laser generated hot electron dynamics via copper K{sub ?} imaging and proton acceleration  

SciTech Connect

Simultaneous experimental measurements of copper K{sub ?} imaging and the maximum target normal sheath acceleration proton energies from the rear target surface are compared for various target thicknesses. For the T-cubed laser (?4 J, 400 fs) at an intensity of ?2 × 10{sup 19} W cm{sup ?2}, the hot electron divergence is determined to be ?{sub HWHM}?22{sup °} using a K{sub ?} imaging diagnostic. The maximum proton energies are measured to follow the expected reduction with increasing target thickness. Numerical modeling produces copper K{sub ?} trends for both signal level and electron beam divergence that are in good agreement with the experiment. A geometric model describing the electron beam divergence reproduces the maximum proton energy trends observed from the experiment and the fast electron density and the peak electric field observed in the numerical modeling.

Willingale, L.; Thomas, A. G. R.; Maksimchuk, A; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109 (United States)] [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109 (United States); Morace, A. [University of California-San Diego, La Jolla, California 92093 (United States) [University of California-San Diego, La Jolla, California 92093 (United States); Università di Milano-Biocca, Piazza della Scienza 3, 20126 Milano (Italy); Bartal, T.; Kim, J.; Beg, F. N. [University of California-San Diego, La Jolla, California 92093 (United States)] [University of California-San Diego, La Jolla, California 92093 (United States); Stephens, R. B.; Wei, M. S. [General Atomics, San Diego, California 92121 (United States)] [General Atomics, San Diego, California 92121 (United States)

2013-12-15

72

T2* and proton density measurement of normal human lung parenchyma using submillisecond echo time gradient echo magnetic resonance imaging  

Microsoft Academic Search

Objective: To obtain T2* and proton density measurements of normal human lung parenchyma in vivo using submillisecond echo time (TE) gradient echo (GRE) magnetic resonance (MR) imaging. Materials and methods: Six normal volunteers were scanned using a 1.5-T system equipped with a prototype enhanced gradient (GE Signa, Waukausha, WI). Images were obtained during breath-holding with acquisition times of 7–16 s.

Hiroto Hatabu; David C. Alsop; John Listerud; Mathieu Bonnet; Warren B. Gefter

1999-01-01

73

Response functions of Fuji imaging plates to monoenergetic protons in the energy range 0.6-3.2 MeV  

NASA Astrophysics Data System (ADS)

We have measured the responses of Fuji MS, SR, and TR imaging plates (IPs) to protons with energies ranging from 0.6 to 3.2 MeV. Monoenergetic protons were produced with the 3.5 MV AIFIRA (Applications Interdisciplinaires de Faisceaux d'Ions en Région Aquitaine) accelerator at the Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG). The IPs were irradiated with protons backscattered off a tantalum target. We present the photo-stimulated luminescence response of the IPs together with the fading measurements for these IPs. A method is applied to allow correction of fading effects for variable proton irradiation duration. Using the IP fading corrections, a model of the IP response function to protons was developed. The model enables extrapolation of the IP response to protons up to proton energies of 10 MeV. Our work is finally compared to previous works conducted on Fuji TR IP response to protons.

Bonnet, T.; Comet, M.; Denis-Petit, D.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Aleonard, M. M.

2013-01-01

74

An imaging proton spectrometer for short-pulse laser plasma experiments  

NASA Astrophysics Data System (ADS)

The ultraintense short pulse laser pulses incident on solid targets can generate energetic protons. In addition to their potentially important applications such as in cancer treatments and proton fast ignition, these protons are essential to understand the complex physics of intense laser plasma interaction. To better characterize these laser-produced protons, we designed and constructed a novel spectrometer that will not only measure proton energy distribution with high resolution but also provide its angular characteristics. The information obtained from this spectrometer compliments those from commonly used diagnostics including radiochromic film packs, CR39 nuclear track detectors, and nonimaging magnetic spectrometers. The basic characterizations and sample data from this instrument are presented.

Chen, Hui; Hazi, A. U.; van Maren, R.; Chen, S. N.; Fuchs, J.; Gauthier, M.; Le Pape, S.; Rygg, J. R.; Shepherd, R.

2010-10-01

75

Diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy ( 1H MRS) in schizophrenic subjects and normal controls  

Microsoft Academic Search

Several proton magnetic resonance spectroscopy (1H MRS) studies in schizophrenia have found reduced N-acetyl aspartate (NAA) concentrations in pre-frontal and temporal regions of the brain. Reductions in NAA may reflect abnormalities of neuronal structure (e.g. reduced neuronal density or viability) or abnormalities of neuronal function. Diffusion tensor imaging (DTI) measures diffusion anisotropy, an indicator of the structural integrity of a

Robby M. Steel; Mark E. Bastin; Sarah McConnell; Ian Marshall; David G. Cunningham-Owens; Stephen M. Lawrie; Eve C. Johnstone; Jonathan J. K. Best

2001-01-01

76

MR Imaging and Proton MR Spectroscopy in A-to-G Substitution at Nucleotide Position 3243 of Leucine Transfer RNA  

Microsoft Academic Search

Summary: MR imaging of the brain in a 38-year-old woman with maternally inherited diabetes and deafness (MIDD) showed extensive subcortical and basal ganglia high signal intensity on T2-weighted studies though she was neurolog- ically asymptomatic. High-signal-intensity changes were also seen in the basal ganglia on T1-weighted studies. Proton MR spectroscopy showed increased lactate, an in- creased choline\\/creatine ratio, and a

James Bowen; Todd Richards; Kenneth Maravilla

77

On-line monitoring and PET imaging of the positron- emitting activity created in tissue by proton radiotherapy beams  

NASA Astrophysics Data System (ADS)

Proton radiotherapy is a powerful tool in the local control of cancer. The advantages of proton radiotherapy over gamma-ray therapy arise from the phenomenon known as the Bragg peak. This phenomenon enables large doses to be delivered to well-defined volumes while sparing surrounding healthy tissue. To fully realize the potential of this technique the location of the high dose volume must be controlled very accurately. An imaging system was designed and tested to monitor the positron- emitting activity created by the beam as a means of verifying the beams range and determining tissue composition. Design studies of the detection system are presented, the data acquisition system used is described and the results of on-line experiments with proton beams are presented. The depth-distribution of positron-emitting activity created by proton radiotherapy beams was imaged on-line using this system. Decay data was acquired and imaged between beam pulses and after the irradiation. Over 80% of the initial positron-emitting activity is from 15O which has a half-life of 122 seconds. The residual range of the treatment beam below the energy threshold for producing 15O is 0.3 cm. Consequently, the end of the activity distribution and the location of the Bragg peak are well correlated in homogenous tissue. The results show that the range of a 150 MeV proton radiotherapy beam may be verified after a single beam pulse to within a detectors width of the imaging system. The integrated total dose delivered to the patient may also be monitored by observing the increase in the number of coincidence events detected between successive beam pulses. It is also shown that in some situations the width of the plateau region of a Spread-Out Bragg Peak (SOBP) may be inferred from the fall of activity at the distal end of the distribution. Radioisotopic imaging may be performed along the beam path if decay data is collected after the treatment is completed. It is shown that using this technique, variations in elemental composition in inhomogenous treatment volumes may be identified and used to locate anatomical landmarks. Radioisotopic imaging also reveals that 14O is created well beyond the Bragg peak, apparently by secondary neutrons.

Litzenberg, Dale William

1997-11-01

78

MR imaging and in vivo proton spectroscopy of the brain in neonates with hypoxic ischemic encephalopathy  

Microsoft Academic Search

Introduction: A number of studies have suggested the potential utility of in vivo proton MR spectroscopy for the evaluation of brain injury in the asphyxiated neonates. We present our initial experience with in vivo proton MR spectroscopy in neonates who were diagnosed as having hypoxic injury on clinical examination and the severity of the insult was graded using Sarnat staging.

G. K Malik; M Pandey; R Kumar; S Chawla; B Rathi; R. K Gupta

2002-01-01

79

N-Acetylaspartate Distribution in Proton Spectroscopic Images of Ischemic Stroke Relationship to Infarct Appearance on T2Weighted Magnetic Resonance Imaging  

Microsoft Academic Search

Background and Purpose—It is generally considered that tissue that appears abnormal on T2 MRI is already infarcted and that any penumbra lies outside the T2-visible lesion. We investigated the distribution of infarcted tissue using proton spectroscopic MRI. Methods—In patients with symptoms of acute hemispheric ischemic stroke, imaged within a maximum of 3 days of stroke, we explored the distribution of

J. M. Wild; J. M. Wardlaw; I. Marshall; C. P. Warlow

80

Amide proton transfer imaging of the breast at 3 T: establishing reproducibility and possible feasibility assessing chemotherapy response.  

PubMed

Chemical exchange saturation transfer imaging can generate contrast that is sensitive to amide protons associated with proteins and peptides (termed amide proton transfer, APT). In breast cancer, APT contrast may report on underlying changes in microstructural tissue composition. However, to date, there have been no developments or applications of APT chemical exchange saturation transfer to breast cancer. As a result, the aims of this study were to (i) experimentally explore optimal scan parameters for breast chemical exchange saturation transfer near the amide resonance at 3 T, (ii) establish the reliability of APT imaging of healthy fibroglandular tissue, and (iii) demonstrate preliminary results on APT changes in locally advanced breast cancer observed during the course of neoadjuvant chemotherapy. Chemical exchange saturation transfer measurements were experimentally optimized on cross-linked bovine serum albumin phantoms, and the reliability of APT imaging was assessed in 10 women with no history of breast disease. The mean difference between test-retest APT values was not significantly different from zero, and the individual difference values were not dependent on the average APT value. The 95% confidence interval limits were ±0.70% (? = 0.05), and the repeatability was 1.91. APT measurements were also performed in three women before and after one cycle of chemotherapy. Following therapy, APT increased in the one patient with progressive disease and decreased in the two patients with a partial or complete response. Together, these results suggest that APT imaging may report on treatment response in these patients. PMID:22907893

Dula, Adrienne N; Arlinghaus, Lori R; Dortch, Richard D; Dewey, Blake E; Whisenant, Jennifer G; Ayers, Gregory D; Yankeelov, Thomas E; Smith, Seth A

2013-07-01

81

Characterization of middle cerebral artery occlusion infarct development in the rat using fast nuclear magnetic resonance proton spectroscopic imaging and diffusion-weighted imaging.  

PubMed

A nuclear magnetic resonance study of the middle cerebral artery occlusion in the rat is presented. Experiments were performed on seven animals before and after occlusion, which occurred in situ. The emphasis in this study was on evaluating rapid proton spectroscopic imaging. Data were acquired with experimental durations of between 4 and 15 minutes for a 32 by 32 spatial matrix, with 64 spectroscopic data points per spatial element. The spectroscopic data were interleaved with diffusion-weighted nuclear magnetic resonance water images of the same slice. The study was terminated at about 6 hours after occlusion. The brains were then frozen in liquid nitrogen for biochemical imaging. The results showed that the signal from N-acetyl aspartate decreased and that of lactate increased within the infarcted region. The temporal course of these intensity changes varied between animals. Nineteen cortical spreading depressions (CSD) were observed by electrophysiologic monitoring during the experiments. Of these, 11 could be unambiguously detected in the lactate images, and a further 3 were on the threshold of detectability. As only a single slice could be examined, it is possible that the centers of depression for the remaining 6 CSD were outside the slice. To the authors' knowledge, this is the first report of the measurement of CSD using proton spectroscopic imaging. Thus, it is shown that this method is valuable not only in following the continuous evolution of proton metabolites with a good spatial and temporal resolution, but also in observing transient phenomena which are believed to play an important role in the expansion of the infarcted territory. PMID:9663505

Norris, D G; Hoehn-Berlage, M; Dreher, W; Kohno, K; Busch, E; Schmitz, B

1998-07-01

82

Synthesis of a DOTA(Gd3+)-conjugate of proton-pump inhibitor pantoprazole for gastric wall imaging studies  

PubMed Central

Magnetic resonance imaging (MRI) is used to evaluate gastrointestinal (GI) structure and functions in humans. Despite filling the viscus lumen with a contrast agent, visualization of the viscus wall is limited. To overcome this limitation, we de novo synthesized a conjugate that covalently combines a Gd-based MRI contrast agent, encaged with a chelating agent (DOTA), with pantoprazole, which is a widely used proton pump inhibitor that binds to proton pumps in the stomach and colon. The DOTA linkage was installed at a mechanism-based strategic location in the pantoprazole molecule to minimize a possible negative effect of the structural modification on the drug. It is anticipated that by defining the wall of the stomach and colon, this compound will facilitate functional MRI of the GI tract in humans.

Maharvi, Ghulam M.; Bharucha, Adil E.; Fauq, Abdul H.

2014-01-01

83

Synthesis of a DOTA (Gd3+)-conjugate of proton-pump inhibitor pantoprazole for gastric wall imaging studies.  

PubMed

Magnetic resonance imaging (MRI) is used to evaluate gastrointestinal (GI) structure and functions in humans. Despite filling the viscus lumen with a contrast agent, visualization of the viscus wall is limited. To overcome this limitation, we de novo synthesized a conjugate that covalently combines a Gd-based MRI contrast agent, encaged with a chelating agent (DOTA), with pantoprazole, which is a widely used proton pump inhibitor that binds to proton pumps in the stomach and colon. The DOTA linkage was installed at a mechanism-based strategic location in the pantoprazole molecule to minimize a possible negative effect of the structural modification on the drug. It is anticipated that by defining the wall of the stomach and colon, this compound will facilitate functional MRI of the GI tract in humans. PMID:23511016

Maharvi, Ghulam M; Bharucha, Adil E; Fauq, Abdul H

2013-05-01

84

Application of flat panel digital imaging for improvement of ocular melanoma patient set-up in proton beam therapy  

NASA Astrophysics Data System (ADS)

In order to reduce the dose to surrounding critical tissues and also minimize the probability of recurrence of the tumor the placement of radiation fields relative to patient anatomy is very essential in proton beam therapy of ocular tumors. To achieve this objective, patient setup and field placement have been verified before treatment by analyzing the portal images obtained with Polaroid film-camera system. The Polaroid films are becoming expensive and obsolete, making new methods of verifying the patient treatment position essential. The objective of this study was to implement an orthogonal flat panel digital imaging (FPDI) system as a tool to image-guided radiation therapy (IGRT) on the UC Davis cyclotron proton beam therapy line and to use the system for patient setup verification. The image quality of the system is sufficient to see an air hole with a diameter of 0.5 mm at a depth of 9 mm, in a 10 cm Lucite phantom. The subject contrast of the FPDI system varied from 16% to 29% by varying the size of the air hole in the phantom from 1 to 5 mm and changing the depth from 9 to 15 mm. The subject contrast for 0.5 mm air hole was 11%. The comparison of the setup variations as measured from Polaroid port films and FPDI was 0.1±0.7 mm in the X-direction, 0.2±0.2 mm in the Y-direction and 0.04±0.1 mm in Z-direction, respectively. The day-to-day positional variations in-patient set-ups were studied for 30 patients using the FPDI system. The patient position set-up on first day of treatment [defined by the X, Y, Z coordinates of the chair and head holder] was registered as the reference image. The comparison of day-to-day patient position with reference image indicated net translation along the three orthogonal axes as 0.3±1.88 mm in right-left direction, -0.3±1.78 in superior-inferior direction and -0.6±2.8 mm in anterior-posterior direction. The image quality of the FPDI system was sufficient to clearly reveal the radio-opaque markers on the digital image. In conclusion a FPDI system can accurately replace the Polaroid system and will facilitate daily portal alignment and true electronic IGRT verification of patient position and tumor location relative to the proton beam.

Daftari, Inder K.; Essert, Timothy; Phillips, Theodore L.

2009-01-01

85

Magnetic resonance imaging of the canine and feline eye, orbit, and optic nerves and its clinical application  

PubMed Central

The purpose of this study was to investigate magnetic resonance imaging of the normal canine and feline eye, orbit and optic nerves using proton density-weighted, T1-weighted and T2-weighted images. The clinical application of magnetic resonance imaging in veterinary ophthalmology was also investigated using three clinical cases: a feline orbital melanoma, a feline optic nerve meningioma, and a canine orbital fibrosarcoma. Gadolinium diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging was completed on the case of feline optic nerve meningioma. Magnetic resonance imaging provides excellent anatomical detail of the canine and feline eye, orbit, and optic nerves due to its superior soft tissue contrast, and its multiplanar and multislice imaging capability. Therefore it is of value for diagnostic imaging of some ophthalmic and neuro-ophthalmic conditions in the dog and cat. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8.

Grahn, Bruce H.; Stewart, Wendy A.; Towner, Rheal A.; Noseworthy, Michael D.

1993-01-01

86

Imaging the proton via hard exclusive production in diffractive pp scattering  

SciTech Connect

We discuss the prospects for probing Generalized Parton Distributions (GPDs) via exclusive production of a high-mass system (H = heavy quarkonium, di-photon, di-jet, Higgs boson) in diffractive pp scattering, pp -> p + H + p. In such processes the interplay of hard and soft interactions gives rise to a diffraction pattern in the final-state proton transverse momenta, which is sensitive to the transverse spatial distribution of partons in the colliding protons. We comment on the plans for diffractive pp measurements at RHIC and LHC. Such studies could complement future measurements of GPDs in hard exclusive ep scattering (JLab, COMPASS, EIC).

Charles Hyde; Leonid Frankfurt; Mark Strikman; Christian Weiss

2007-05-21

87

Optical time projection chamber for imaging of two-proton decay of 45Fe nucleus  

Microsoft Academic Search

We present a design of the gaseous detector for 3-D measurement of the topology of a recently discovered radioactive decay of 45Fe nucleus which involves simultaneous emission of two protons from the ground state. Our apparatus, called optical time projection chamber, consists of several parallel wire-mesh electrodes inside a gaseous medium which form the conversion region and the multistage charge

M. Cwiok; W. Dominik; Z. Janas; A. Korgul; K. Miernik; M. Pfutzner; M. Sawicka; A. Wasilewski

2004-01-01

88

Real-time correction of magnetic field inhomogeneity-induced image distortions for MRI-guided conventional and proton radiotherapy  

NASA Astrophysics Data System (ADS)

Image-guided radiotherapy has the potential to increase the success of treatment by decreasing uncertainties concerning tumour position and shape. We pursue integrated diagnostic quality MRI functionality with radiotherapy systems to boost the possibilities of image guidance by providing images with superior soft-tissue contrast during treatment. However, the use of MR images in radiotherapy can be hindered by geometrical distortions due to magnetic field inhomogeneity problems. A method for fast correction of these distortions is presented and implemented. Using a 20 cm square phantom containing a regular grid, a measure of residual deformation after correction is established. At very low gradient strength (which leads to large deformations) a maximum displacement of 2.9 mm is shown to be reduced to 0.63 mm. Next, the method is applied in vivo to the case of pelvic body contour extraction for prostate radiotherapy treatment planning. Here, again with low gradient strengths, distortions of up to 6 mm can be reduced to 2 mm. All results are provided within a lag time of 8 ms. We discuss implications of image distortions for MRI-guided photon and proton radiotherapy separately, since the dose-depth curves in these treatments are very different. We argue that, although field inhomogeneities cannot be prevented from occurring, distortion correction is not always necessary in practice. This work opens new possibilities for investigating on-line MRI-based plan adaptations and ultimately MRI-based treatment planning.

Crijns, S. P. M.; Raaymakers, B. W.; Lagendijk, J. J. W.

2011-01-01

89

Two-exponential analysis of spin-spin proton relaxation times in MR imaging using surface coils  

SciTech Connect

Proton relaxation time measurements were performed on a standard whole body MR imager operating at 1.5 T using a conventional surface coil of the manufacturer. A combined CP/CPMG multiecho, multislice sequence was used for the T1 and T2 relaxation time measurements. Two repetition times of 2000 ms (30 echoes) and 600 ms (2 echoes) with 180 degrees-pulse intervals of 2 tau = 22 ms were interleaved in this sequence. A two-exponential T2 analysis of each pixel of the spin-echo images was computed in a case of an acoustic neurinoma. The two-exponential images show a short component (T2S) due to white and gray matter and a long component (T2S) due to the cerebrospinal fluid. In the fatty tissue two components with T2S = 35 {plus minus} 3 ms and T2L = 164 {plus minus} 7 ms were measured. Comparing with Gd-DTPA imaging the relaxation time images show a clear differentiation of vital tumor tissue and cerebrospinal fluid.

Schad, L.R.; Brix, G.; Semmler, W.; Gueckel, F.L.; Lorenz, W.J. (Institute of Radiology and Pathophysiology, Heidelberg (Germany, F.R.))

1989-07-01

90

Three-dimensional imaging of aerosol particles with scanning proton microprobe in a confocal arrangement  

Microsoft Academic Search

We have reconstructed three-dimensional (3D) element-specific distributions of aerosol microparticles captured in a thick quartz filter. The characteristic x rays were induced by a proton microprobe and detected by a Si(Li) spectrometer equipped with a polycapillary lens. Combining a fine microbeam scanning in the lateral plane with the sample movement parallel to the beam axis, the aerosol particles were driven

M. Zitnik; P. Pelicon; N. Grlj; A. G. Karydas; D. Sokaras; R. Schuetz; B. Kanngiesser

2008-01-01

91

A case of Sjögren-Larsson syndrome with minimal MR imaging findings facilitated by proton spectroscopy.  

PubMed

We present a 5-year-old girl who was ultimately diagnosed with Sjögren-Larsson syndrome (SLS). Although her MRI findings were minimal compared to previously published cases, prominent and characteristic abnormal lipid peaks on single-voxel proton MR spectroscopy ((1)H-MRS) facilitated the diagnosis. This case emphasizes the importance and usefulness of (1)H-MRS in diagnosing SLS. PMID:21713441

Tachibana, Yasuhiko; Aida, Noriko; Enomoto, Keisuke; Iai, Mizue; Kurosawa, Kenji

2012-03-01

92

Optical time projection chamber for imaging of two-proton decay of \\/sup 45\\/Fe nucleus  

Microsoft Academic Search

We present a design of the gaseous detector for three-dimensional (3-D) measurement of the topology of a recently discovered radioactive decay of 45Fe nucleus which involves simultaneous emission of two protons from the ground state. Our apparatus, called an optical time projection chamber (OTPC), consists of several parallel wire-mesh electrodes inside a gaseous medium which form the conversion region and

M. Cwiok; W. Dominik; Z. Janas; A. Korgul; K. Miernik; M. Pfutzner; M. Sawicka; A. Wasilewski

2005-01-01

93

The rapid secondary electron imaging system of the proton beam writer at CIBA  

Microsoft Academic Search

The recent years have witnessed a proliferation of research involving proton beam (p-beam) writing. This has prompted investigations into means of optimizing the process of p-beam writing so as to make it less time consuming and more efficient. One such avenue is the improvement of the pre-writing preparatory procedures that involves beam focusing and sample alignment which is centred on

C. N. B. Udalagama; A. A. Bettiol; J. A. van Kan; E. J. Teo; F. Watt

2007-01-01

94

Calibration of CT Hounsfield units for proton therapy treatment planning: use of kilovoltage and megavoltage images and comparison of parameterized methods.  

PubMed

Proton beam range is of major concern, in particular, when images used for dose computations are artifacted (for example in patients with surgically treated bone tumors). We investigated several conditions and methods for determination of computed tomography Hounsfield unit (CT-HU) calibration curves, using two different conversion schemes. A stoichiometric methodology was used on either kilovoltage (kV) or megavoltage (MV) CT images and the accuracy of the calibration methods was evaluated. We then studied the effects of metal artifacts on proton dose distributions using metallic implants in rigid phantom mimicking clinical conditions. MV-CT images were used to evaluate relative proton stopping power in certain high density implants, and a methodology is proposed for accurate delineation and dose calculation, using a combined set of kV- and MV-CT images. Our results show good agreement between measurements and dose calculations or relative proton stopping power determination (<5%). The results also show that range uncertainty increases when only kV-CT images are used or when no correction is made on artifacted images. However, differences between treatment plans calculated on corrected kV-CT data and MV-CT data remained insignificant in the investigated patient case, even with streak artifacts and volume effects that reduce the accuracy of manual corrections. PMID:23719506

De Marzi, L; Lesven, C; Ferrand, R; Sage, J; Boulé, T; Mazal, A

2013-06-21

95

Calibration of CT Hounsfield units for proton therapy treatment planning: use of kilovoltage and megavoltage images and comparison of parameterized methods  

NASA Astrophysics Data System (ADS)

Proton beam range is of major concern, in particular, when images used for dose computations are artifacted (for example in patients with surgically treated bone tumors). We investigated several conditions and methods for determination of computed tomography Hounsfield unit (CT-HU) calibration curves, using two different conversion schemes. A stoichiometric methodology was used on either kilovoltage (kV) or megavoltage (MV) CT images and the accuracy of the calibration methods was evaluated. We then studied the effects of metal artifacts on proton dose distributions using metallic implants in rigid phantom mimicking clinical conditions. MV-CT images were used to evaluate relative proton stopping power in certain high density implants, and a methodology is proposed for accurate delineation and dose calculation, using a combined set of kV- and MV-CT images. Our results show good agreement between measurements and dose calculations or relative proton stopping power determination (<5%). The results also show that range uncertainty increases when only kV-CT images are used or when no correction is made on artifacted images. However, differences between treatment plans calculated on corrected kV-CT data and MV-CT data remained insignificant in the investigated patient case, even with streak artifacts and volume effects that reduce the accuracy of manual corrections.

De Marzi, L.; Lesven, C.; Ferrand, R.; Sage, J.; Boulé, T.; Mazal, A.

2013-06-01

96

Evaluation of 10MeV proton irradiation on 5.5 Mpixel scientific CMOS image sensor  

NASA Astrophysics Data System (ADS)

We evaluate the effects of 10 MeV proton irradiation on the performance of a 5.5 Mpixel scientific grade CMOS image sensor based on a 5T pixel architecture with pinned photodiode and transfer gate. The sensor has on-chip dual column level amplifiers and 11-bit single slope analog to digital converters (ADC) for high speed readout and wide dynamic range. The operation of the sensor is programmable and controlled by on-chip digital control modules. Since the image sensor features two identical halves capable of operating independently, we used a mask to expose only one half of the sensor to the proton beam, leaving the other half intact to serve as a reference. In addition, the pixel array and the digital logic control section were irradiated separately, at dose rates varying from 4 rad/s to 367 rad/s, for a total accumulated dose of 146 krad(Si) to assess the radiation effects on these key components of the image sensor. We report the resulting damage effects on the performance of the sensor including increase in dark current, temporal noise, dark spikes, transient effects and latch-up. The dark signal increased by about 55 e-/pixel after exposure to 14 krad (Si) and the dark noise increased from about 2.75e- to 6.5e-. While the number of hot pixels increased by 6 percent and the dark signal non uniformity degraded, no catastrophic failure mechanisms were observed during the tests, and the sensor did not suffer from functional failures.

Vu, Paul; Fowler, Boyd; Rodricks, Brian; Balicki, Janusz; Mims, Steve..; Li, Wang

2010-10-01

97

Evaluation of a stochastic reconstruction algorithm for use in Compton camera imaging and beam range verification from secondary gamma emission during proton therapy  

PubMed Central

In this paper, we study the feasibility of using the stochastic origin ensemble (SOE) algorithm for reconstructing images of secondary gammas emitted during proton radiotherapy from data measured with a three-stage Compton camera. The purpose of this study was to evaluate the quality of the images of the gamma rays emitted during proton irradiation produced using the SOE algorithm and to measure how well the images reproduce the distal falloff of the beam. For our evaluation, we performed a Monte Carlo simulation of an ideal three-stage Compton camera positioned above and orthogonal to a proton pencil beam irradiating a tissue phantom. Scattering of beam protons with nuclei in the phantom produces secondary gamma rays, which are detected by the Compton camera and used as input to the SOE algorithm. We studied the SOE reconstructed images as a function of the number of iterations, the voxel probability parameter, and the number of detected gammas used by the SOE algorithm. We quantitatively evaluated the capabilities of the SOE algorithm by calculating and comparing the normalized mean square error (NMSE) of SOE reconstructed images. We also studied the ability of the SOE reconstructed images to predict the distal falloff of the secondary gamma production in the irradiated tissue. Our results show that the images produced with the SOE algorithm converge in ~10,000 iterations, with little improvement to the image NMSE for iterations above this number. We found that the statistical noise of the images is inversely proportional to the ratio of the number of gammas detected to the SOE voxel probability parameter value. In our study, the SOE predicted distal falloff of the reconstructed images agrees with the Monte Carlo calculated distal falloff of the gamma emission profile in the phantom to within ±0.6 mm for the positions of maximum emission (100%) and 90%, 50%, and 20% distal falloff of the gamma emission profile. We conclude that the SOE algorithm is an effective method for reconstructing images of a proton pencil beam from the data collected by an ideal Compton camera and that these images accurately model the distal falloff of secondary gamma emission during proton irradiation.

Mackin, Dennis; Peterson, Steve; Beddar, Sam; Polf, Jerimy

2012-01-01

98

Detection of small degree of nonuniformity in dialysate flow in hollow-fiber dialyzer using proton magnetic resonance imaging.  

PubMed

A small degree of nonuniformity in dialysate flow in a hollow-fiber dialyzer was detected using proton magnetic resonance imaging (MRI). Since paramagnetic ions reduce the spin-lattice relaxation time of protons around them, MRI can detect Gd in water. An aqueous solution of a chelate compound of Gd was impulsively injected into the dialysate flow path at a flow rate of 500 cm(3) /m, which is that utilized in actual dialysis. Despite the apparent elimination of Gd from the dialysate flow path by the newly injected dialysate fluid after the injection of Gd was terminated, MRI revealed that Gd remained in the interior of the hollow fiber. The observed structure pattern of the Gd concentration profile revealed that the dialysate flow had a small degree of nonuniformity despite the currently established design to restrict channeling in dialysate flow. Local nonuniformity of the hollow-fiber density and vortex generation in the dialysate flow were considered to cause the nonuniformity in the dialysate flow. PMID:15062938

Osuga, T; Obata, T; Ikehira, H

2004-04-01

99

Bio-metals imaging and speciation in cells using proton and synchrotron radiation X-ray microspectroscopy  

PubMed Central

The direct detection of biologically relevant metals in single cells and of their speciation is a challenging task that requires sophisticated analytical developments. The aim of this article is to present the recent achievements in the field of cellular chemical element imaging, and direct speciation analysis, using proton and synchrotron radiation X-ray micro- and nano-analysis. The recent improvements in focusing optics for MeV-accelerated particles and keV X-rays allow application to chemical element analysis in subcellular compartments. The imaging and quantification of trace elements in single cells can be obtained using particle-induced X-ray emission (PIXE). The combination of PIXE with backscattering spectrometry and scanning transmission ion microscopy provides a high accuracy in elemental quantification of cellular organelles. On the other hand, synchrotron radiation X-ray fluorescence provides chemical element imaging with less than 100 nm spatial resolution. Moreover, synchrotron radiation offers the unique capability of spatially resolved chemical speciation using micro-X-ray absorption spectroscopy. The potential of these methods in biomedical investigations will be illustrated with examples of application in the fields of cellular toxicology, and pharmacology, bio-metals and metal-based nano-particles.

Ortega, Richard; Deves, Guillaume; Carmona, Asuncion

2009-01-01

100

Magnetization Transfer Imaging and Proton MR Spectroscopy in the Evaluation of Axonal Injury: Correlation with Clinical Outcome after Traumatic Brain Injury  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Current imaging does not permit quantification of neural injury after traumatic brain injury (TBI) and therefore limits both the development of new treatments and the appropriate counseling of patients concerning prognosis. We evaluated the utility of magnetization transfer ratio (MTR) and proton MR spectroscopy in identifying pa- tients with neuronal injury after TBI. METHODS: Thirty patients with

Grant Sinson; Linda J. Bagley; Kim M. Cecil; Maria Torchia; Joseph C. McGowan; Robert E. Lenkinski; Tracy K. McIntosh; Robert I. Grossman

101

Liver regeneration in humans is characterized by significant changes in cellular phosphorus metabolism: assessment using proton-decoupled 31P-magnetic resonance spectroscopic imaging.  

PubMed

In the present study we applied proton-decoupled 31P magnetic resonance spectroscopic imaging (MRSI) to noninvasively assess liver metabolism in patients who had undergone a partial hepatectomy (PH). Proton-decoupled 31P chemical shift imaging was performed in 47 patients 2-28 days following major hepatectomy, and the results were compared with those from eight control subjects. All studies were performed on a 1.5T MR imager (General Electric, Milwaukee, WI) equipped with a stand-alone proton decoupler. A 31P-1H resonator pair was used for data acquisition, and 31P data were obtained in 34 min. Liver regeneration was characterized by increases in phosphoethanolamine (PE), and decreases in nucleoside triphosphates (NTP), glycerophosphoethanolamine (GPE), and glycerophosphocholine (GPC). These alterations were most marked 48-72 hr after hepatectomy and returned to baseline within 3 weeks. The level of PE measured by MRSI was also found to depend on the percentage of liver that was removed, while changes in levels of cellular high energy phosphates were independent of the size of liver resection. Implementation of proton-decoupling was critical for assessing individual phosphomonoester and phosphodiester components. This study demonstrates that 31P MRSI can be used to assess metabolic changes in humans during liver regeneration, and may be useful for assessing derangement of the regenerative process or guiding adjuvant chemotherapies. PMID:16032692

Zakian, Kristen L; Koutcher, Jason A; Malhotra, Sandeep; Thaler, Howard; Jarnagin, William; Schwartz, Lawrence; Fong, Yuman

2005-08-01

102

In Vivo Proton-Electron Double-Resonance Imaging of Extracellular Tumor pH Using an Advanced Nitroxide Probe  

PubMed Central

A variable radio frequency proton–electron double-resonance imaging (VRF PEDRI) approach for pH mapping of aqueous samples has been recently developed (Efimova et al. J. Magn. Reson. 2011, 209, 227–232). A pH map is extracted from two PEDRI acquisitions performed at electron paramagnetic resonance (EPR) frequencies of protonated and unprotonated forms of a pH-sensitive probe. To translate VRF PEDRI to an in vivo setting, an advanced pH probe was synthesized. Probe deuteration resulted in a narrow spectral line of 1.2 G compared to a nondeuterated analogue line width of 2.1 G allowing for an increase of Overhauser enhancements and reduction in rf power deposition. Binding of the probe to the cell-impermeable tripeptide, glutathione (GSH), allows for targeting to extracellular tissue space for monitoring extracellular tumor acidosis, a prognostic factor in tumor pathophysiology. The probe demonstrated pH sensitivity in the 5.8–7.8 range, optimum for measurement of acidic extracellular tumor pH (pHe). In vivo VRF PEDRI was performed on Met-1 tumor-bearing mice. Compared to normal mammary glands with a neutral mean pHe (7.1 ± 0.1), we observed broader pH distribution with acidic mean pHe (6.8 ± 0.1) in tumor tissue. In summary, VRF PEDRI in combination with a newly developed pH probe provides an analytical approach for spatially resolved noninvasive pHe monitoring, in vivo.

Samouilov, Alexandre; Efimova, Olga V.; Bobko, Andrey A.; Sun, Ziqi; Petryakov, Sergey; Eubank, Timothy D.; Trofimov, Dmitrii G.; Kirilyuk, Igor A.; Grigor'ev, Igor A.; Takahashi, Wataru; Zweier, Jay L.; Khramtsov, Valery V.

2014-01-01

103

A prototype of image-guided outcome analysis for prostate proton therapy patients based on DICOM-RT ePR  

NASA Astrophysics Data System (ADS)

Last year, we presented the infrastructure for a medical imaging informatics DICOM-RT based ePR system for patients treated with Proton Therapy (PT). The ePR has functionality to integrate patients' imaging and informatics data and perform outcomes analysis with patient and physician profiling in order to provide clinical decision support and suggest courses of treatment. In this paper, we present the development of a prototype for the image-guided outcomes analysis for prostate cancer patient based on DICOM-RT ePR. This ePR system, using DICOM-RT and DICOM-ION objects as well as clinical and biological parameters, provides tools to evaluate treatment plans and assess the outcomes of the patient's treatment; hence, it promotes more successful treatment planning for new prostate cancer patients treated with proton therapy.

Le, Anh; Documet, Jorge; Sullivan, Ashley; Liu, Brent

2009-02-01

104

MR Imaging and Proton Spectroscopy of Neuronal Injury in Late-Onset GM2 Gangliosidosis  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Despite the ubiquity of GM2 gangliosides accumulation in patients with late-onset GM2 gangliosidosis (GM2G), the only clinical MR imaging-apparent brain abnormality is profound cerebellar atrophy. The goal of this study was to detect the presence and assess the extent of neuroaxonal injury in the normal-appearing gray and white matter (NAGM and NAWM) of these patients. METHODS: During

Matilde Inglese; Annette O. Nusbaum; Gregory M. Pastores; John Gianutsos; Edwin H. Kolodny; Oded Gonen

105

Proton Storms - Aurora - Climate  

Microsoft Academic Search

Years ago a strong correlation was found between climate and geomagnetic storms. Is this still a surprise? Some months ago observations via IMAGE and Cluster satellites showed a possible missing link. Earth-directed proton storms can pervade the magnetic shield causing proton aurora and a positive charge of all drops and ice crystals of a cloud. Then these cloud-particles push each

L. Körtvelyessy

2004-01-01

106

Cortical metabolite alterations in abstinent cocaine and cocaine/alcohol-dependent subjects: proton magnetic resonance spectroscopic imaging  

PubMed Central

Chronic abuse of cocaine or alcohol is associated with structural, neuropathological and cognitive impairments that have been documented extensively. Little is known, however, about neurobiochemical changes in chronic substance abusers. We performed MRI and multi-slice brain proton magnetic resonance spectroscopic imaging (MRSI) to assess neuronal viability (via N-acetylaspartate (NAA)) and white matter metabolite status in 22 4-months-abstinent individuals dependent on crack cocaine only and on both crack cocaine and alcohol. Compared to 11 non-dependent controls we found (1) significantly lower NAA measures in the dorsolateral prefrontal cortex of the combined cocaine-dependent groups; (2) comparable spatial distribution and magnitude of these NAA effects for both cocaine-dependent groups; (3) higher choline-containing metabolites in frontal white matter of individuals dependent on both cocaine and alcohol; (4) absence of brain atrophy in both abstinent cocaine-dependent samples; and (5) partial recovery from prefrontal cortical NAA loss, primarily with abstinence from alcohol. The MRSI findings suggest preferential neuronal damage to the frontal cortex of both cocaine-dependent samples and gliosis in frontal white matter of individuals dependent on both alcohol and cocaine, conditions that persist for more than 4 months of abstinence.

MEYERHOFF, D. J.; BLOOMER, C.; SCHUFF, N.; EZEKIEL, F.; NORMAN, D.; CLARK, W.; WEINER, M. W.; FEIN, G.

2009-01-01

107

Dose-Volume Differences for Computed Tomography and Magnetic Resonance Imaging Segmentation and Planning for Proton Prostate Cancer Therapy  

SciTech Connect

Purpose: To determine the influence of magnetic-resonance-imaging (MRI)-vs. computed-tomography (CT)-based prostate and normal structure delineation on the dose to the target and organs at risk during proton therapy. Methods and Materials: Fourteen patients were simulated in the supine position using both CT and T2 MRI. The prostate, rectum, and bladder were delineated on both imaging modalities. The planning target volume (PTV) was generated from the delineated prostates with a 5-mm axial and 8-mm superior and inferior margin. Two plans were generated and analyzed for each patient: an MRI plan based on the MRI-delineated PTV, and a CT plan based on the CT-delineated PTV. Doses of 78 Gy equivalents (GE) were prescribed to the PTV. Results: Doses to normal structures were lower when MRI was used to delineate the rectum and bladder compared with CT: bladder V50 was 15.3% lower (p = 0.04), and rectum V50 was 23.9% lower (p = 0.003). Poor agreement on the definition of the prostate apex was seen between CT and MRI (p = 0.007). The CT-defined prostate apex was within 2 mm of the apex on MRI only 35.7% of the time. Coverage of the MRI-delineated PTV was significantly decreased with the CT-based plan: the minimum dose to the PTV was reduced by 43% (p < 0.001), and the PTV V99% was reduced by 11% (p < 0.001). Conclusions: Using MRI to delineate the prostate results in more accurate target definition and a smaller target volume compared with CT, allowing for improved target coverage and decreased doses to critical normal structures.

Yeung, Anamaria R. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Vargas, Carlos E. [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)], E-mail: c2002@ufl.edu; Falchook, Aaron; Louis, Debbie C. [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Olivier, Kenneth [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Keole, Sameer; Yeung, Daniel [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Mendenhall, Nancy P. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Li Zuofeng [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

2008-12-01

108

Altered development of prefrontal neurons in rhesus monkeys with neonatal mesial temporo-limbic lesions: a proton magnetic resonance spectroscopic imaging study  

Microsoft Academic Search

Focal brain damage occurring early in development can have widespread repercussions throughout the developing brain. In living adult rhesus monkeys, we studied the long-term effects of early mesial temporo-limbic (MTL) lesions on prefrontal cortex (PFC) neurons using proton magnetic resonance spectroscopic imaging (1H-MRSI), an in vivo neurochemical assay technique for measuring signals from metabolites such as N-acetyl-aspartate (NAA, a neuronal

Alessandro Bertolino; Richard C. Saunders; Venkata S. Mattay; Jocelyne Bachevalier; Joseph A. Frank; Daniel R. Weinberger

1997-01-01

109

Identification of the Epileptogenic Lobe in Neocortical Epilepsy with Proton MR Spectroscopic Imaging  

PubMed Central

Summary Purpose The aim of this study was to evaluate the usefulness of multislice magnetic resonance spectroscopic imaging (MRSI) in combination with tissue segmentation for the identification of the epileptogenic focus in neocortical epilepsy (NE). Methods Twenty patients with NE (10 with MRI-visible malformations, 10 with normal MRI) and 19 controls were studied. In controls, N-acetylaspartate NAA/Cr and NAA/Cho of all voxels of a given lobe were expressed as a function of white matter, and thresholds were determined by calculating the 95% prediction intervals (PIs) for NAA/Cr and NAA/Cho. Voxels with NAA/Cr or NAA/Cho values less than the 95% PI were defined as “pathological.” Z-scores were calculated. Depending on the magnitude of those z-scores, we used two different methods (score-localization or forced-localization) to identify in a given subject the lobe with the highest percentage of pathological voxels, which was supposed to represent the epileptogenic lobe. Results MRSI correctly identified the lobe containing the epileptogenic focus as defined by EEG in 65% of the NE patients. MRSI localization of the focus was correct in 70% of the patients with an MRI-visible malformation and in 60% of the patients with normal MRI. Of the patients, 15% had metabolically abnormal brain regions outside the epileptogenic lobe, and 35% of the patients had evidence for secondary hippocampal damage. Conclusions MRSI may be helpful for the identification of the epileptogenic focus in NE patients, even in NE with normal MRI.

Mueller, Susanne G.; Laxer, Kenneth D.; Barakos, Jerome A.; Cashdollar, Nathan; Flenniken, Derek L.; Vermathen, Peter; Matson, Gerald B.; Weiner, Michael W.

2009-01-01

110

Proton therapy  

MedlinePLUS

... cells, proton therapy uses a beam of special particles called protons. Doctors can better aim proton beams ... D. Do we have enough evidence to implement particle therapy as standard treatment in lung cancer? A ...

111

Proton Therapy  

MedlinePLUS

... which holds two types of particles—protons and neutrons. The nucleus is surrounded by electrons. In proton ... reactor that can smash atoms to release proton, neutron, and helium ion beams. In this highly specialized ...

112

Longitudinal absolute metabolite quantification of white and gray matter regions in healthy controls using proton MR spectroscopic imaging.  

PubMed

The purpose of this study was to evaluate quality parameters, metabolite concentrations and concentration ratios, and to investigate the reproducibility of quantitative proton magnetic resonance spectroscopic imaging ((1)H-MRSI) of selected white and gray matter regions of healthy adults. 2D-quantitative short-TE (1)H-MRSI spectra were obtained at 1.5T from the healthy human brain. Subjects (n?=?12) were scanned twice with an interval of six months. Absolute metabolite concentrations were obtained based on coil loading, taking into account differences in sensitivity of the phased-array head coil. Spectral quality parameters, absolute metabolite concentrations, concentration ratios, and their reproducibility were determined and compared between time-points using a repeated measures general linear model. The quality of the spectra of selected brain areas was good, as determined by a mean spectral linewidth between 4.8 and 7.3 Hz (depending on the region). No significant differences between the two time-points were observed for spectral quality, concentrations, or concentration ratios. The mean intrasubject coefficient of variation (CoV) varied between 4.0 and 8.5% for total N-acetylaspartate, 7.2 and 10.8% for total creatine, 5.9 and 9.8% for myo-inositol, and 8.0 and 13.3% for choline, and remained below 20% for glutamate. CoV was generally lower when concentration ratios were considered. The study shows that longitudinal quantitative short-TE (1)H-MRSI generates reproducible absolute metabolite concentrations in healthy human white and gray matter. This may serve as a background for longitudinal clinical studies in adult patients. PMID:24399803

Wiebenga, Oliver T; Klauser, Antoine M; Nagtegaal, Gijsbert J A; Schoonheim, Menno M; Barkhof, Frederik; Geurts, Jeroen J G; Pouwels, Petra J W

2014-03-01

113

Optical spectroscopy and imaging of colour centres in lithium fluoride crystals and thin films irradiated by 3 MeV proton beams  

NASA Astrophysics Data System (ADS)

Lithium fluoride is a well-known dosimeter material and it is currently under investigation also for high-resolution radiation imaging detectors based on colour centre photoluminescence. In order to extend their applications, proton beams of 3 MeV energy, produced by a linear accelerator, were used to irradiate LiF crystals and thin films in the fluence range of 1010–1015 protons/cm2. The irradiation induces the formation of colour centres, mainly the primary F centre and the aggregate F2 and F3+ defects, which are stable at room temperature. By optical pumping in the blue spectral region, the F2 and F3+ centres emit broad photoluminescence bands in the visible spectral range. By conventional fluorescence microscopy, the integrated photoluminescence intensity was carefully measured in LiF crystals and thin films as a function of the irradiation fluence: a linear optical response was obtained in a large range of fluence, which is dependent on the used LiF samples. Colour centres concentrations were estimated in LiF crystals by optical absorption spectroscopy. It was possible to record the transversal proton beam intensity profile by acquiring the photoluminescence image of the irradiated spots on LiF films.

Piccinini, M.; Ambrosini, F.; Ampollini, A.; Carpanese, M.; Picardi, L.; Ronsivalle, C.; Bonfigli, F.; Libera, S.; Vincenti, M. A.; Montereali, R. M.

2014-05-01

114

Proton therapy in clinical practice  

PubMed Central

Radiation dose escalation and acceleration improves local control but also increases toxicity. Proton radiation is an emerging therapy for localized cancers that is being sought with increasing frequency by patients. Compared with photon therapy, proton therapy spares more critical structures due to its unique physics. The physical properties of a proton beam make it ideal for clinical applications. By modulating the Bragg peak of protons in energy and time, a conformal radiation dose with or without intensity modulation can be delivered to the target while sparing the surrounding normal tissues. Thus, proton therapy is ideal when organ preservation is a priority. However, protons are more sensitive to organ motion and anatomy changes compared with photons. In this article, we review practical issues of proton therapy, describe its image-guided treatment planning and delivery, discuss clinical outcome for cancer patients, and suggest challenges and the future development of proton therapy.

Liu, Hui; Chang, Joe Y.

2011-01-01

115

Variable flip angle imaging and fat suppression in combined gradient and spin-echo (GREASE) techniques  

SciTech Connect

Conventional proton density and T2-weighted spin-echo images are susceptible to motion induced artifact, which is exacerbated by lipid signals. Gradient moment nulling can reduce motion artifact but lengthens the minimum TE, degrading the proton density contrast. We designed a pulse sequence capable of optimizing proton density and T2-weighted contrast while suppressing lipid signals and motion induced artifacts. Proton density weighting was obtained by rapid readout gradient reversal immediately after the excitation RF pulse, within a conventional spin-echo sequence. By analyzing the behavior of the macroscopic magnetization and optimizing excitation flip angle, we suppressed T1 contribution to the image, thereby enhancing proton density and T2-weighted contrast with a two- to four-fold reduction of repetition time. This permitted an increased number of averages to be used, reducing motion induced artifacts. Fat suppression in the presence of motion was investigated in two groups of 8 volunteers each by (i) modified Dixon technique, (ii) selective excitation, and (iii) hybrid of both. Elimination of fat signal by the first technique was relatively uniform across the field of view, but it did not fully suppress the ghosts originating from fat motion. Selective excitation, while sensitive to the main field inhomogeneity, largely eliminated the ghosts (0.21 +/- 0.05 vs. 0.29 +/- 0.06, p less than 0.01). The hybrid of both techniques combined with bandwidth optimization, however, showed the best results (0.17 +/- 0.04, p less than 0.001). Variable flip-angle imaging allows optimization of image contrast which, along with averaging and effective fat suppression, significantly improves gradient- and spin-echo imaging, particularly in the presence of motion.

Vinitski, S.; Mitchell, D.G.; Szumowski, J.; Burk, D.L. Jr.; Rifkin, M.D. (Thomas Jefferson Univ. Hospital, Philadelphia, PA (USA))

1990-01-01

116

A Proton Beam Therapy System Dedicated to Spot-Scanning Increases Accuracy with Moving Tumors by Real-Time Imaging and Gating and Reduces Equipment Size  

PubMed Central

Purpose A proton beam therapy (PBT) system has been designed which dedicates to spot-scanning and has a gating function employing the fluoroscopy-based real-time-imaging of internal fiducial markers near tumors. The dose distribution and treatment time of the newly designed real-time-image gated, spot-scanning proton beam therapy (RGPT) were compared with free-breathing spot-scanning proton beam therapy (FBPT) in a simulation. Materials and Methods In-house simulation tools and treatment planning system VQA (Hitachi, Ltd., Japan) were used for estimating the dose distribution and treatment time. Simulations were performed for 48 motion parameters (including 8 respiratory patterns and 6 initial breathing timings) on CT data from two patients, A and B, with hepatocellular carcinoma and with clinical target volumes 14.6 cc and 63.1 cc. The respiratory patterns were derived from the actual trajectory of internal fiducial markers taken in X-ray real-time tumor-tracking radiotherapy (RTRT). Results With FBPT, 9/48 motion parameters achieved the criteria of successful delivery for patient A and 0/48 for B. With RGPT 48/48 and 42/48 achieved the criteria. Compared with FBPT, the mean liver dose was smaller with RGPT with statistical significance (p<0.001); it decreased from 27% to 13% and 28% to 23% of the prescribed doses for patients A and B, respectively. The relative lengthening of treatment time to administer 3 Gy (RBE) was estimated to be 1.22 (RGPT/FBPT: 138 s/113 s) and 1.72 (207 s/120 s) for patients A and B, respectively. Conclusions This simulation study demonstrated that the RGPT was able to improve the dose distribution markedly for moving tumors without very large treatment time extension. The proton beam therapy system dedicated to spot-scanning with a gating function for real-time imaging increases accuracy with moving tumors and reduces the physical size, and subsequently the cost of the equipment as well as of the building housing the equipment.

Shimizu, Shinichi; Miyamoto, Naoki; Matsuura, Taeko; Fujii, Yusuke; Umezawa, Masumi; Umegaki, Kikuo; Hiramoto, Kazuo; Shirato, Hiroki

2014-01-01

117

Evaluation of the dosimetric impact of interfractional anatomical variations on prostate proton therapy using daily in-room CT images  

SciTech Connect

Purpose: To quantify interfractional anatomical variations and their dosimetric impact during the course of fractionated proton therapy (PT) of prostate cancer and to assess the robustness of the current treatment planning techniques. Methods: Simulation and daily in-room CT scans from ten prostate carcinoma patients were analyzed. PT treatment plans (78 Gy in 39 fractions of 2 Gy) were created on the simulation CT, delivering 25 fractions to PTV1 (expanded from prostate and seminal vesicles), followed by 14 boost fractions to PTV2 (expanded from prostate). Plans were subsequently applied to daily CT, with beams aligned to the prostate center in the sagittal plane. For five patients having a sufficiently large daily imaging volume, structure contours were manually drawn, and plans were evaluated for all CT sets. For the other five patients, the plans were evaluated for six selected fractions. The daily CT was matched to the simulation CT through deformable registration. The registration accuracy was validated for each fraction, and the three patients with a large number of accurately registered fractions were used for dose accumulation. Results: In individual fractions, the coverage of the prostate, seminal vesicles, and PTV1 was generally maintained at the corresponding prescription dose. For PTV2, the volume covered by the fractional prescription dose of 2 Gy (i.e., V2) was, on average, reduced by less than 3% compared to the simulation plan. Among the 225 (39 x 5 + 6 x 5) fractions examined, 15 showed a V2 reduction larger than 5%, of which ten were caused by a large variation in rectal gas, and five were due to a prostate shift in the craniocaudal direction. The fractional dose to the anterior rectal wall was found to increase for one patient who had large rectal gas volume in 25 of the 39 fractions, and another who experienced significant prostate volume reduction during the treatment. The fractional bladder dose generally increased with decreasing fullness. In the total accumulated dose for the three patients after excluding a few fractions with inaccurate registration due to a large amount of rectal gas (a condition inconsistent with RTOG protocol), 98.5%, 96.6%, and 98.2% of the PTV2 received the prescription dose of 78 Gy. The V75 and V70 of the anterior rectal wall and bladder both remained within tolerance. Conclusions: The results confirm that the PT planning techniques and dose constraints used at our institution ensure that target coverage to the prescription dose is maintained in the presence of interfractional anatomical variations. Dose coverage in individual fractions can be compromised, and normal tissue dose increased, due to deviations in the bladder and rectal volume compared to the simulation plans or progressive changes in the prostate volume during the treatment. Deviations from the plan can be reduced with efforts aimed at maintaining consistent daily patient anatomy.

Wang, Yi; Efstathiou, Jason A.; Sharp, Gregory C.; Lu, Hsiao-Ming; Trofimov, Alexei V. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 (United States); Frank Ciernik, I. [Radiation Oncology, Dessau Medical Center, Dessau 06847, Germany and Center for Clinical Research, Zurich University Hospital, Zurich 8006 (Switzerland)

2011-08-15

118

Enantioselective Protonation  

PubMed Central

Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. These laboratory transformations have proven useful for the preparation of a number of valuable organic compounds.

Mohr, Justin T.; Hong, Allen Y.; Stoltz, Brian M.

2010-01-01

119

Cobalt60 and proton radiation effects on large format, 2-D, CCD arrays for an Earth imaging application  

Microsoft Academic Search

Cobalt60 and 10-MeV proton irradiations have been carried out on n-buried channel frame transfer CCDs (charge coupled devices) in order to study changes in charge transfer efficiency (CTE) and dark current for room temperature, 1 ?s\\/pixel, readout conditions. Bias dependence and post-annealing effects were observed for ionization damage. CTE effects are explained in terms of capture and emission from deep

G. R. Hopkinson

1992-01-01

120

Characterization of creatine guanidinium proton exchange by water-exchange (WEX) spectroscopy for absolute-pH CEST imaging in vitro.  

PubMed

Chemical exchange saturation transfer (CEST) enables indirect detection of small metabolites in tissue by MR imaging. To optimize and interpret creatine-CEST imaging we characterized the dependence of the exchange-rate constant k(sw) of creatine guanidinium protons in aqueous creatine solutions as a function of pH and temperature T in vitro. Model solutions in the low pH range (pH?=?5-6.4) were measured by means of water-exchange (WEX)-filtered ¹H NMR spectroscopy on a 3?T whole-body MR tomograph. An extension of the Arrhenius equation with effective base-catalyzed Arrhenius parameters yielded a general expression for k(sw) (pH, T). The defining parameters were identified as the effective base-catalyzed rate constant k(b,eff) (298.15?K)?=?(3.009 ± 0.16) × 10? ?Hz?l/mol and the effective activation energy E(A,b,eff) ?=?(32.27 ± 7.43) kJ/mol at a buffer concentration of c(buffer) ?=?(1/15) M. As expected, a strong dependence of k(sw) on temperature was observed. The extrapolation of the exchange-rate constant to in vivo conditions (pH?=?7.1, T?=?37?°C) led to the value of the exchange-rate constant k(sw) ?=?1499?Hz. With the explicit function k(sw) (pH, T) available, absolute-pH CEST imaging could be realized and experimentally verified in vitro. By means of our calibration method it is possible to adjust the guanidinium proton exchange-rate constant k(sw) to any desired value by preparing creatine model solutions with a specific pH and temperature. PMID:24535718

Goerke, Steffen; Zaiss, Moritz; Bachert, Peter

2014-05-01

121

SElf-gated Non-Contrast-Enhanced FUnctional Lung imaging (SENCEFUL) using a quasi-random fast low-angle shot (FLASH) sequence and proton MRI.  

PubMed

Obtaining functional information on the human lung is of tremendous interest in the characterization of lung defects and pathologies. However, pulmonary ventilation and perfusion maps usually require contrast agents and the application of electrocardiogram (ECG) triggering and breath holds to generate datasets free of motion artifacts. This work demonstrates the possibility of obtaining highly resolved perfusion-weighted and ventilation-weighted images of the human lung using proton MRI and the SElf-gated Non-Contrast-Enhanced FUnctional Lung imaging (SENCEFUL) technique. The SENCEFUL technique utilizes a two-dimensional fast low-angle shot (FLASH) sequence with quasi-random sampling of phase-encoding (PE) steps for data acquisition. After every readout, a short additional acquisition of the non-phase-encoded direct current (DC) signal necessary for self-gating was added. By sorting the quasi-randomly acquired data according to respiratory and cardiac phase derived from the DC signal, datasets of representative respiratory and cardiac cycles could be accurately reconstructed. By application of the Fourier transform along the temporal dimension, functional maps (perfusion and ventilation) were obtained. These maps were compared with dynamic contrast-enhanced (DCE, perfusion) as well as standard Fourier decomposition (FD, ventilation) reference datasets. All datasets were additionally scored by two experienced radiologists to quantify image quality. In addition, one initial patient examination using SENCEFUL was performed. Functional images of healthy volunteers and a patient diagnosed with hypoplasia of the left pulmonary artery and left-sided pulmonary fibrosis were successfully obtained. Perfusion-weighted images corresponded well to DCE-MRI data; ventilation-weighted images offered a significantly better depiction of the lung periphery compared with standard FD. Furthermore, the SENCEFUL technique hints at a potential clinical relevance by successfully detecting a perfusion defect in the patient scan. It can be concluded that SENCEFUL enables highly resolved ventilation- and perfusion-weighted maps of the human lung to be obtained using proton MRI, and might be interesting for further clinical evaluation. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24820869

Fischer, André; Weick, Stefan; Ritter, Christian O; Beer, Meinrad; Wirth, Clemens; Hebestreit, Helge; Jakob, Peter M; Hahn, Dietbert; Bley, Thorsten; Köstler, Herbert

2014-08-01

122

An imaging informatics-based system utilizing DICOM objects for treating pain in spinal cord injury patients utilizing proton beam radiotherapy  

NASA Astrophysics Data System (ADS)

Many US combat personnel have sustained nervous tissue trauma during service, which often causes Neuropathic pain as a side effect and is difficult to manage. However in select patients, synapse lesioning can provide significant pain control. Our goal is to determine the effectiveness of using Proton Beam radiotherapy for treating spinal cord injury (SCI) related neuropathic pain as an alternative to invasive surgical lesioning. The project is a joint collaboration of USC, Spinal Cord Institute VA Healthcare System, Long Beach, and Loma Linda University. This is first system of its kind that supports integration and standardization of imaging informatics data in DICOM format; clinical evaluation forms outcomes data and treatment planning data from the Treatment planning station (TPS) utilized to administer the proton therapy in DICOM-RT format. It also supports evaluation of SCI subjects for recruitment into the clinical study, which includes the development, and integration of digital forms and tools for automatic evaluation and classification of SCI pain. Last year, we presented the concept for the patient recruitment module based on the principle of Bayesian decision theory. This year we are presenting the fully developed patient recruitment module and its integration to other modules. In addition, the DICOM module for integrating DICOM and DICOM-RT-ION data is also developed and integrated. This allows researchers to upload animal/patient study data into the system. The patient recruitment module has been tested using 25 retrospective patient data and DICOM data module is tested using 5 sets of animal data.

Verma, Sneha K.; Liu, Brent J.; Chun, Sophia; Gridley, Daila S.

2014-03-01

123

An experimental approach to improve the Monte Carlo modelling of offline PET/CT-imaging of positron emitters induced by scanned proton beams.  

PubMed

We report on the experimental campaign carried out at the Heidelberg Ion-Beam Therapy Center (HIT) to optimize the Monte Carlo (MC) modelling of proton-induced positron-emitter production. The presented experimental strategy constitutes a pragmatic inverse approach to overcome the known uncertainties in the modelling of positron-emitter production due to the lack of reliable cross-section data for the relevant therapeutic energy range. This work is motivated by the clinical implementation of offline PET/CT-based treatment verification at our facility. Here, the irradiation induced tissue activation in the patient is monitored shortly after the treatment delivery by means of a commercial PET/CT scanner and compared to a MC simulated activity expectation, derived under the assumption of a correct treatment delivery. At HIT, the MC particle transport and interaction code FLUKA is used for the simulation of the expected positron-emitter yield. For this particular application, the code is coupled to externally provided cross-section data of several proton-induced reactions. Studying experimentally the positron-emitting radionuclide yield in homogeneous phantoms provides access to the fundamental production channels. Therefore, five different materials have been irradiated by monoenergetic proton pencil beams at various energies and the induced ?(+) activity subsequently acquired with a commercial full-ring PET/CT scanner. With the analysis of dynamically reconstructed PET images, we are able to determine separately the spatial distribution of different radionuclide concentrations at the starting time of the PET scan. The laterally integrated radionuclide yields in depth are used to tune the input cross-section data such that the impact of both the physical production and the imaging process on the various positron-emitter yields is reproduced. The resulting cross-section data sets allow to model the absolute level of measured ?(+) activity induced in the investigated targets within a few per cent. Moreover, the simulated distal activity fall-off positions, representing the central quantity for treatment monitoring in terms of beam range verification, are found to agree within 0.6 mm with the measurements at different initial beam energies in both homogeneous and heterogeneous targets. PMID:23835872

Bauer, J; Unholtz, D; Kurz, C; Parodi, K

2013-08-01

124

An experimental approach to improve the Monte Carlo modelling of offline PET/CT-imaging of positron emitters induced by scanned proton beams  

NASA Astrophysics Data System (ADS)

We report on the experimental campaign carried out at the Heidelberg Ion-Beam Therapy Center (HIT) to optimize the Monte Carlo (MC) modelling of proton-induced positron-emitter production. The presented experimental strategy constitutes a pragmatic inverse approach to overcome the known uncertainties in the modelling of positron-emitter production due to the lack of reliable cross-section data for the relevant therapeutic energy range. This work is motivated by the clinical implementation of offline PET/CT-based treatment verification at our facility. Here, the irradiation induced tissue activation in the patient is monitored shortly after the treatment delivery by means of a commercial PET/CT scanner and compared to a MC simulated activity expectation, derived under the assumption of a correct treatment delivery. At HIT, the MC particle transport and interaction code FLUKA is used for the simulation of the expected positron-emitter yield. For this particular application, the code is coupled to externally provided cross-section data of several proton-induced reactions. Studying experimentally the positron-emitting radionuclide yield in homogeneous phantoms provides access to the fundamental production channels. Therefore, five different materials have been irradiated by monoenergetic proton pencil beams at various energies and the induced ?+ activity subsequently acquired with a commercial full-ring PET/CT scanner. With the analysis of dynamically reconstructed PET images, we are able to determine separately the spatial distribution of different radionuclide concentrations at the starting time of the PET scan. The laterally integrated radionuclide yields in depth are used to tune the input cross-section data such that the impact of both the physical production and the imaging process on the various positron-emitter yields is reproduced. The resulting cross-section data sets allow to model the absolute level of measured ?+ activity induced in the investigated targets within a few per cent. Moreover, the simulated distal activity fall-off positions, representing the central quantity for treatment monitoring in terms of beam range verification, are found to agree within 0.6 mm with the measurements at different initial beam energies in both homogeneous and heterogeneous targets. Based on work presented at the Third European Workshop on Monte Carlo Treatment Planning (Seville, 15-18 May 2012).

Bauer, J.; Unholtz, D.; Kurz, C.; Parodi, K.

2013-08-01

125

PROTON MICROSCOPY AT FAIR  

SciTech Connect

Proton radiography was invented in the 1990's at Los Alamos National Laboratory (LANL) as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time hundreds of dynamic proton radiography experiments have been performed at LANL and a facility has been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia for similar applications in dynamic material studies. Recently an international effort has investigated a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located in Darmstadt, Germany. This new Proton microscope for FAIR(PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a window for understanding dynamic material properties at new length scales. It is also proposed to install the PRIOR system at the GSI Helmholtzzentrum fuer Schwerionenforschung before installation at FAIR for dynamic experiments with different drivers including high explosives, pulsed power and lasers. The design of the proton microscope and expected radiographic performance is presented.

Merrill, F. E.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Golubev, A. A.; Turtikov, V. I. [Institute for Theoretical and Experimental Physics, 117269 Moscow (Russian Federation); Varentsov, D. [GSI Helmoholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany)

2009-12-28

126

Proton magnetic resonance imaging of flow motion of heavy water injected into a hollow fiber dialyzer filled with saline.  

PubMed

Observations using MRI were performed for the motion of heavy water injected into a hollow fiber dialyzer. A cylindrical dialyzer houses a bundle of 10,000 hollow fibers. Because blood components permeate through the hollow fiber membrane from the interior to the exterior of the hollow fiber, which is the dialysate flow path, uniformity of dialysate flow is required. The dialyzer was initially filled with saline and heavy water was injected into the inlet port of the dialysate flow path. MRI tuned for protons could distinguish the injected heavy water from the already present saline. Due to the specific gravity difference, MRI could observe the sedimentation of the injected heavy water flowing beneath the already present saline. The uniformity of the dialysate flow was supported by the finding that the injected heavy water brought about uniform sedimentation and distributed the already present saline uniformly throughout the entire volume of the dialyzer. PMID:15062937

Osuga, T; Obata, T; Ikehira, H

2004-04-01

127

A comparative study between the imaging system and the optical tracking system in proton therapy at CNAO  

PubMed Central

The synergy between in-room imaging and optical tracking, in co-operation with highly accurate robotic patient handling represents a concept for patient-set-up which has been implemented at CNAO (Centro Nazionale di Adroterapia Oncologica). In-room imaging is based on a double oblique X-ray projection system; optical tracking consists of the detection of the position of spherical markers placed directly on the patient's skin or on the immobilization devices. These markers are used as external fiducials during patient positioning and dose delivery. This study reports the results of a comparative analysis between in-room imaging and optical tracking data for patient positioning within the framework of high-precision particle therapy. Differences between the optical tracking system (OTS) and the imaging system (IS) were on average within the expected localization accuracy. On the first 633 fractions for head and neck (H&N) set-up procedures, the corrections applied by the IS, after patient positioning using the OTS only, were for the mostly sub-millimetric regarding the translations (0.4±1.1 mm) and sub-gradual regarding the rotations (0.0°±0.8°). On the first 236 fractions for pelvis localizations the amplitude of the corrections applied by the IS after preliminary optical set-up correction were moderately higher and more dispersed (translations: 1.3±2.9 mm, rotations 0.1±0.9°). Although the indication of the OTS cannot replace information provided by in-room imaging devices and 2D-3D image registration, the reported data show that OTS preliminary correction might greatly support image-based patient set-up refinement and also provide a secondary, independent verification system for patient positioning.

Desplanques, Maxime; Tagaste, Barbara; Fontana, Giulia; Pella, Andrea; Riboldi, Marco; Fattori, Giovanni; Donno, Andrea; Baroni, Guido; Orecchia, Roberto

2013-01-01

128

Minimum acquisition methods for simultaneously imaging T1, T2, and proton density with B1 correction and no spin-echoes  

NASA Astrophysics Data System (ADS)

The spin lattice (T1) and spin-spin (T2) relaxation times, along with the proton density (PD) contain almost all of the information that 1H MRI routinely uses in clinical diagnosis and research, but are seldom imaged directly. Here, three methods for directly imaging T1, T2, and PD with the least possible number of acquisitions - three, are presented. All methods utilize long 0° self-refocusing adiabatic pre-pulses instead of spin-echoes to encode the T2 information prior to a conventional gradient-echo MRI sequence. T1 information is encoded by varying the flip-angle (FA) in the ‘Dual-? Dual-FA’ and ‘Four-FA’ methods, or the sequence repetition period, TR, in the ‘Dual-? Dual-TR’ method. Inhomogeneity in the FA distribution and slice-selection profile are recognized as the main error sources for T1 measurements. The former is remedied by integrating an extra FA-dependent acquisition into the ‘Four-FA’ method to provide self-corrected T1, T2, PD, and FA in just four acquisitions - again, the minimum possible. Slice profile errors - which manifest as differences between 2D and 3D T1 measurements, can be addressed by Bloch equation analysis and experimental calibration. All three methods are validated in phantom studies, and the ‘Dual-? Dual-FA’ and ‘Four-FA’ methods are validated in human brain studies using standard partial saturation and spin-echo methods for reference. The new methods offer a minimum-acquisition option for imaging single-component T1, T2, and PD. ‘Four-FA’ performs best overall in accuracy, with high efficiency per unit accuracy vs. existing methods when B1-inhomogeneity is appropriately addressed.

Wang, Guan; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.

2014-05-01

129

Minimum acquisition methods for simultaneously imaging T(1), T(2), and proton density with B(1) correction and no spin-echoes.  

PubMed

The spin lattice (T(1)) and spin-spin (T(2)) relaxation times, along with the proton density (PD) contain almost all of the information that (1)H MRI routinely uses in clinical diagnosis and research, but are seldom imaged directly. Here, three methods for directly imaging T(1), T(2), and PD with the least possible number of acquisitions - three, are presented. All methods utilize long 0° self-refocusing adiabatic pre-pulses instead of spin-echoes to encode the T(2) information prior to a conventional gradient-echo MRI sequence. T(1) information is encoded by varying the flip-angle (FA) in the 'Dual-? Dual-FA' and 'Four-FA' methods, or the sequence repetition period, TR, in the 'Dual-? Dual-TR' method. Inhomogeneity in the FA distribution and slice-selection profile are recognized as the main error sources for T(1) measurements. The former is remedied by integrating an extra FA-dependent acquisition into the 'Four-FA' method to provide self-corrected T(1), T(2), PD, and FA in just four acquisitions - again, the minimum possible. Slice profile errors - which manifest as differences between 2D and 3D T(1) measurements, can be addressed by Bloch equation analysis and experimental calibration. All three methods are validated in phantom studies, and the 'Dual-? Dual-FA' and 'Four-FA' methods are validated in human brain studies using standard partial saturation and spin-echo methods for reference. The new methods offer a minimum-acquisition option for imaging single-component T(1), T(2), and PD. 'Four-FA' performs best overall in accuracy, with high efficiency per unit accuracy vs. existing methods when B(1)-inhomogeneity is appropriately addressed. PMID:24705365

Wang, Guan; El-Sharkawy, AbdEl-Monem M; Bottomley, Paul A

2014-05-01

130

Serial water changes in human skeletal muscles on exercise studied with proton magnetic resonance spectroscopy and imaging  

Microsoft Academic Search

In vivo\\u000a 1H-magnetic resonance imaging (MRI) enabled us to study the distribution of water in living tissues and to document changes\\u000a in human skeletal muscles during physical exercise. The purpose of the present study was to determine the total muscle water\\u000a changes after exercise using water in1H-MR spectroscopy and to compare these changes to the signal intensity change on T2*-weighted

Toru Ogino; Hiroo Ikehira; Noboru Arimizu; Hideshige Moriya; Koichi Wakimoto; Satoru Nishikawa; Hideaki Shiratsuchi; Hirotoshi Kato; Fumio Shishido; Yukio Tateno

1994-01-01

131

On proton CT reconstruction using MVCT-converted virtual proton projections  

SciTech Connect

Purpose: To describe a novel methodology of converting megavoltage x-ray projections into virtual proton projections that are otherwise missing due to the proton range limit. These converted virtual proton projections can be used in the reconstruction of proton computed tomography (pCT). Methods: Relations exist between proton projections and multispectral megavoltage x-ray projections for human tissue. Based on these relations, these tissues can be categorized into: (a) adipose tissue; (b) nonadipose soft tissues; and (c) bone. These three tissue categories can be visibly identified on a regular megavoltage x-ray computed tomography (MVCT) image. With an MVCT image and its projection data available, the x-ray projections through heterogeneous anatomy can be converted to the corresponding proton projections using predetermined calibration curves for individual materials, aided by a coarse segmentation on the x-ray CT image. To show the feasibility of this approach, mathematical simulations were carried out. The converted proton projections, plotted on a proton sinogram, were compared to the simulated ground truth. Proton stopping power images were reconstructed using either the virtual proton projections only or a blend of physically available proton projections and virtual proton projections that make up for those missing due to the range limit. These images were compared to a reference image reconstructed from theoretically calculated proton projections. Results: The converted virtual projections had an uncertainty of {+-}0.8% compared to the calculated ground truth. Proton stopping power images reconstructed using a blend of converted virtual projections (48%) and physically available projections (52%) had an uncertainty of {+-}0.86% compared with that reconstructed from theoretically calculated projections. Reconstruction solely from converted virtual proton projections had an uncertainty of {+-}1.1% compared with that reconstructed from theoretical projections. If these images are used for treatment planning, the average proton range uncertainty is estimated to be less than 1.5% for an imaging dose in the milligray range. Conclusions: The proposed method can be used to convert x-ray projections into virtual proton projections. The converted proton projections can be blended with existing proton projections or can be used solely for pCT reconstruction, addressing the range limit problem of pCT using current therapeutic proton machines.

Wang Dongxu; Mackie, T. Rockwell; Tome, Wolfgang A. [Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242 (United States); Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Morgridge Institute of Research, University of Wisconsin, Madison, Wisconsin 53715 (United States); Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Oncophysics Institute, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461 (United States)

2012-06-15

132

Brain Changes in Long-Term Zen Meditators Using Proton Magnetic Resonance Spectroscopy and Diffusion Tensor Imaging: A Controlled Study  

PubMed Central

Introduction This work aimed to determine whether 1H magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls. Materials and Methods Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. 1H-MRS (1.5 T) of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL) and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC) and fractional anisotropy (FA) by MR-DTI. Results Myo-inositol (mI) was increased in the posterior cingulate gyrus and Glutamate (Glu), N-acetyl-aspartate (NAA) and N-acetyl-aspartate/Creatine (NAA/Cr) was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r?=?0.518; p?=?.019). We also found significant negative correlations between Glu (r?=??0.452; p?=?.045), NAA (r?=??0.617; p?=?.003) and NAA/Cr (r?=??0.448; P?=?.047) in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC) in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r?=??0.4850, p?=?.0066). Conclusions The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators.

Fayed, Nicolas; Lopez del Hoyo, Yolanda; Andres, Eva; Serrano-Blanco, Antoni; Bellon, Juan; Aguilar, Keyla; Cebolla, Ausias; Garcia-Campayo, Javier

2013-01-01

133

Coregistration of quantitative proton magnetic resonance spectroscopic imaging with neuropathological and neurophysiological analyses defines the extent of neuronal impairments in murine human immunodeficiency virus type-1 encephalitis.  

PubMed

Relatively few immune-activated and virus-infected mononuclear phagocytes (MP; perivascular macrophages and microglia) may affect widespread neuronal dysfunction during human immunodeficiency virus type 1 (HIV-1)-associated dementia (HAD). Indeed, histopathological evidence of neuronal dropout often belies the extent of cognitive impairment. To define relationships between neuronal function and histopathology, proton magnetic resonance spectroscopic imaging (1H MRSI) and hippocampal long-term potentiation (LTP) were compared with neuronal and glial immunohistology in a murine model of HIV-1 encephalitis (HIVE). HIV-1(ADA)-infected human monocyte-derived macrophages (MDM) were stereotactically injected into the subcortex of severe combined immunodeficient (SCID) mice. Sham-operated and unmanipulated mice served as controls. Seven days after cell injection, brain histological analyses revealed a focal giant cell encephalitis, with reactive astrocytes, microgliosis, and neuronal dropout. Strikingly, significant reductions in N-acetyl aspartate concentration ([NAA]) and LTP levels in HIVE mice were in both injected and contralateral hemispheres and in brain subregions, including the hippocampus, where neuropathology was limited or absent. The data support the importance of 1H MRSI as a tool for assessing neuronal function for HAD. The data also demonstrate that a highly focal encephalitis can produce global deficits for neuronal function and metabolism. PMID:15825192

Nelson, J A; Dou, H; Ellison, B; Uberti, M; Xiong, H; Anderson, E; Mellon, M; Gelbard, H A; Boska, M; Gendelman, H E

2005-05-15

134

Proton Irradiation Experiment for X-ray Charge-Coupled Devices of the Monitor of All-Sky X-ray Image Mission Onboard the International Space Station: I. Experimental Setup and Measurement of the Charge Transfer Inefficiency  

Microsoft Academic Search

We have investigated the radiation damage effects on a charge-cloupled device (CCD) to be employed in the Japanese X-ray astronomy mission including the monitor of all-sky X-ray image (MAXI) onboard the international space station (ISS). Since low-energy protons release their energy mainly at the charge transfer channel, resulting in a decrease of the charge transfer efficiency, we focused on low-energy

Emi Miyata; Tomoyuki Kamazuka; Hirohiko Kouno; Mitsunori Fukuda; Mototsugu Mihara; Kensaku Matsuta; Hiroshi Tsunemi; Kanenobu Tanaka; Tadanori Minamisono; Hiroshi Tomida; Kazuhisa Miyaguchi

2002-01-01

135

Proton Irradiation Experiment for X-ray Charge-Coupled Devices of the Monitor of All-Sky X-ray Image Mission Onboard the International Space Station: II. Degradation of Dark Current and Identification of Electron Trap Level  

Microsoft Academic Search

We have investigated the radiation damage effects on a charge-coupled device (CCD) to be used for the Japanese X-ray mission, the monitor of all-sky X-ray image (MAXI), onboard the international space station (ISS). A temperature dependence of the dark current as a function of incremental dose is studied. We found that the protons having energy of >292 keV seriously increased

Emi Miyata; Hirohiko Kouno; Daisuke Kamiyama; Tomoyuki Kamazuka; Mototsugu Mihara; Mitsunori Fukuda; Kensaku Matsuta; Hiroshi Tsunemi; Tadanori Minamisono; Hiroshi Tomida; Kazuhisa Miyaguchi

2003-01-01

136

Proton geriatrics  

NASA Astrophysics Data System (ADS)

An SO(10) model with particle spectrum and low energy gauge group identical to that of minimal SU (5) below MX but with a nonstandard charge assignment is shown to agree with the experimental best value of sin2?w(Mw) and the lower bound on the proton lifetime.

Kephart, Thomas W.; Nakagawa, Norio

1984-07-01

137

Cosmic protons  

Microsoft Academic Search

The primary proton spectrum in the kinetic energy range 0.2 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS–91 at an altitude of 380 km. The complete data set combining three shuttle attitudes and including all known systematic effects is presented.

J. Alcaraz; B. Alpat; G. Ambrosi; H. Anderhub; L. Ao; A. Arefiev; P. Azzarello; E. Babucci; L. Baldini; M. Basile; D. Barancourt; F. Barao; G. Barbier; G. Barreira; R. Battiston; R. Becker; U. Becker; L. Bellagamba; P. Béné; J. Berdugo; P. Berges; B. Bertucci; A. Biland; S. Bizzaglia; S. Blasko; G. Boella; M. Boschini; M. Bourquin; L. Brocco; G. Bruni; M. Buenerd; J. D. Burger; W. J. Burger; X. D. Cai; C. Camps; P. Cannarsa; M. Capell; D. Casadei; J. Casaus; G. Castellini; C. Cecchi; Y. H. Chang; H. F. Chen; H. S. Chen; Z. G. Chen; N. A. Chernoplekov; T. H. Chiueh; Y. L. Chuang; F. Cindolo; V. Commichau; A. Contin; P. Crespo; M. Cristinziani; J. P. da Cunha; T. S. Dai; J. D. Deus; N. Dinu; L. Djambazov; I. D'Antone; Z. R. Dong; P. Emonet; J. Engelberg; F. J. Eppling; T. Eronen; G. Esposito; P. Extermann; J. Favier; E. Fiandrini; P. H. Fisher; G. Fluegge; N. Fouque; Yu. Galaktionov; M. Gervasi; P. Giusti; D. Grandi; O. Grimm; W. Q. Gu; K. Hangarter; A. Hasan; V. Hermel; H. Hofer; M. A. Huang; W. Hungerford; M. Ionica; R. Ionica; M. Jongmanns; K. Karlamaa; W. Karpinski; G. Kenney; J. Kenny; W. Kim; A. Klimentov; R. Kossakowski; V. Koutsenko; M. Kraeber; G. Laborie; T. Laitinen; G. Lamanna; G. Laurenti; A. Lebedev; S. C. Lee; G. Levi; P. Levtchenko; C. L. Liu; H. T. Liu; I. Lopes; G. Lu; Y. S. Lu; K. Lübelsmeyer; D. Luckey; W. Lustermann; C. Maña; A. Margotti; F. Mayet; R. R. McNeil; B. Meillon; M. Menichelli; A. Mihul; A. Mourao; A. Mujunen; F. Palmonari; A. Papi; I. H. Park; M. Pauluzzi; F. Pauss; E. Perrin; A. Pesci; A. Pevsner; M. Pimenta; V. Plyaskin; V. Pojidaev; M. Pohl; V. Postolache; N. Produit; P. G. Rancoita; D. Rapin; F. Raupach; D. Ren; Z. Ren; M. Ribordy; J. P. Richeux; E. Riihonen; J. Ritakari; U. Roeser; C. Roissin; R. Sagdeev; G. Sartorelli; A. Schultz von Dratzig; G. Schwering; G. Scolieri; E. S. Seo; V. Shoutko; E. Shoumilov; R. Siedling; D. Son; T. Song; M. Steuer; G. S. Sun; H. Suter; X. W. Tang; Samuel C. C. Ting; S. M. Ting; M. Tornikoski; J. Torsti; J. Trümper; J. Ulbricht; S. Urpo; I. Usoskin; E. Valtonen; J. Vandenhirtz; F. Velcea; E. Velikhov; B. Verlaat; I. Vetlitsky; F. Vezzu; J. P. Vialle; G. Viertel; D. Vité; H. Von Gunten; S. Waldmeier Wicki; W. Wallraff; B. C. Wang; J. Z. Wang; Y. H. Wang; K. Wiik; C. Williams; S. X. Wu; P. C. Xia; J. L. Yan; L. G. Yan; C. G. Yang; M. Yang; S. W. Ye; P. Yeh; Z. Z. Xu; H. Y. Zhang; Z. P. Zhang; D. X. Zhao; G. Y. Zhu; W. Z. Zhu; H. L. Zhuang; A. Zichichi; B. Zimmermann

2000-01-01

138

Technological Advances in Proton Therapy  

NASA Astrophysics Data System (ADS)

Proton therapy has interested radiation oncologists since the 1946 paper by Robert R. Wilson describing the energy deposition of proton beams and suggesting it would be more suitable for radiation treatments than beams of x-rays. For all its proposed benefits, only 25,000 or so cancer patients worldwide have been treated with high-energy proton beams over the last fifty years. However, during the past decade that number has started to rapidly increase. In the United States alone the number of dedicated facilities has grown from two to five in the last three years and will likely double again by the end of the current decade. We will soon be treating as many patients in one year as was treated during the first fifty years of proton therapy. Surprisingly, the reason is because of what has been happening in x-ray radiotherapy. Conventional radiotherapy underwent a dramatic change during the past decade with the introduction of multiple advances in imaging technology and beam delivery methods. The imaging advances include both imaging for treatment planning (multislice CT systems, high resolution MRI, and increasing use of PET) and imaging of the target location in the treatment room. The treatment delivery advances, dominated by methods that permit intensity modulated beam delivery, were made possible by increased computational power and more computer control of the treatment delivery. These imaging and beam delivery advances should benefit proton therapy treatments even more than x-ray treatments because of the better conformation of dose to the target that one can achieve with proton beams. However, because of the small size of the proton therapy community it has had difficulty implementing some of the advances made in x-ray therapy. The treatment planning imaging is also used by proton therapy but the on-treatment imaging and the intensity modulation often must be specially developed for each proton therapy system. This talk will present the developments in these areas that are expected to be implemented in the next few years.

McDonough, James

2008-03-01

139

Comparative study of fast MR imaging: quantitative analysis on image quality and efficiency among various time frames and contrast behaviors.  

PubMed

The purpose of this study is to quantitatively compare the image quality and efficiency provided by widely available fast MR imaging pulse sequences. A composite phantom with various T1 and T2 values and subjected to periodic motion was imaged at 1.5 T. The fast MRI sequences evaluated included fast spin-echo (FSE), single shot fast spin-echo (SSFSE), echo-planar imaging (EPI), multi-slice gradient recalled (MPGR), fast MPGR (FMPGR), and fast multi-slice spoiled gradient echo (FMPSPGR). T1-weighted (T1WI), T2-weighted (T2WI), proton-density-weighted (PDWI), and T2*-weighted (T2*WI) images were evaluated in breath-hold and non-breath-hold time frames. Analysis included measurement of image signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), nonuniformity, ghosting ratio, SNR per unit time and CNR per unit time. Among fast T2WI sequences, FSE with breath-hold time frame resulted in the highest image quality and in superior SNR and CNR efficiency by a factor of 5 or 6 as compared with conventional spin echo sequence. Among fast T1WI sequences, FMPGR and FMPSPGR both with non-breath-hold time frame produced the highest image quality and SNR and CNR efficiency by a factor of greater than 5 as compared with conventional spin echo. Among fast PDWI and T2*WI sequences, FSE produced the highest SNR and CNR, and was maximally efficient with a factors of greater than 6 as compared with conventional spin echo. PMID:12361794

Li, Tao; Mirowitz, Scott A

2002-07-01

140

Infrared Spectroscopy of Protonated Carbonyls: Protonated Glyoxal  

NASA Astrophysics Data System (ADS)

The protonation site of carbonyls is usually at oxygen, allowing studies of the O-H^+ and carbonyl stretch vibrations and their variation with the local chemical environment. We have already studied protonated acetone and its proton-bridged dimer and now extend the study of protonated carbonyls to protonated glyoxal. Glyoxal is the simplest ?-oxoaldehyde, which has the chance to form an intramolecular bridging proton structure upon protonation. Computational chemistry predicts the proton-bridged cis isomer to be the lowest energy structure. The infrared spectrum of mass-selected protonated glyoxal is obtained using infrared photodissociation spectroscopy with Ar tagging. The spectrum shows the presence of only the higher energy trans isomer when compared with purely harmonic calculations. The frequencies of the O-H^+ and carbonyl stretch vibrations of protonated glyoxal are compared to other protonated carbonyls.

Mosley, J. D.; Cheng, T. C.; Duncan, M. A.

2012-06-01

141

An image-based skeletal model for the ICRP reference adult male—specific absorbed fractions for neutron-generated recoil protons  

NASA Astrophysics Data System (ADS)

Recoiling hydrogen nuclei are a principle mechanism for energy deposition from incident neutrons. For neutrons incident on the human skeleton, the small sizes of two contrasting media (trabecular bone and marrow) present unique problems due to a lack of charged-particle (protons) equilibrium. Specific absorbed fractions have been computed for protons originating in the human skeletal tissues for use in computing neutron dose response functions. The proton specific absorbed fractions were computed using a pathlength-based range-energy calculation in trabecular skeletal samples of a 40 year old male cadaver.

Jokisch, D. W.; Rajon, D. A.; Bahadori, A. A.; Bolch, W. E.

2011-11-01

142

Proton Radiography of Inertial Fusion Implosions  

Microsoft Academic Search

A distinctive way of quantitatively imaging inertial fusion implosions has resulted in the characterization of two different types of electromagnetic configurations and in the measurement of the temporal evolution of capsule size and areal density. Radiography with a pulsed, monoenergetic, isotropic proton source reveals field structures through deflection of proton trajectories, and areal densities are quantified through the energy lost

J. R. Rygg; F. H. Séguin; C. K. Li; J. A. Frenje; M. J.-E. Manuel; R. D. Petrasso; R. Betti; J. A. Delettrez; O. V. Gotchev; J. P. Knauer; D. D. Meyerhofer; F. J. Marshall; C. Stoeckl; W. Theobald

2008-01-01

143

Proton scaling  

SciTech Connect

This note presents analytic estimates of the performance of proton beams in remote surveillance for nuclear materials. The analysis partitions the analysis into the eight steps used by a companion note: (1) Air scattering, (2) Neutron production in the ship and cargo, (3) Target detection probability, (4) Signal produced by target, (5) Attenuation of signal by ship and cargo, (6) Attenuation of signal by air, (7) Geometric dilution, and (8) Detector Efficiency. The above analyses indicate that the dominant air scattering and loss mechanisms for particle remote sensing are calculable with reliable and accepted tools. They make it clear that the conversion of proton beams into neutron sources rapidly goes to completion in all but thinnest targets, which means that proton interrogation is for all purposes executed by neutrons. Diffusion models and limiting approximations to them are simple and credible - apart from uncertainty over the cross sections to be used in them - and uncertainty over the structure of the vessels investigated. Multiplication is essentially unknown, in part because it depends on the details of the target and its shielding, which are unlikely to be known in advance. Attenuation of neutron fluxes on the way out are more complicated due to geometry, the spectrum of fission neutrons, and the details of their slowing down during egress. The attenuation by air is large but less uncertain. Detectors and technology are better known. The overall convolution of these effects lead to large but arguably tolerable levels of attenuation of input beams and output signals. That is particularly the case for small, mobile sensors, which can more than compensate for size with proximity to operate reliably while remaining below flux limits. Overall, the estimates used here appear to be of adequate accuracy for decisions. That assessment is strengthened by their agreement with companion calculations.

Canavan, Gregory H [Los Alamos National Laboratory

2009-01-01

144

Development of Proton Computed Tomography for Applications in Proton Therapy  

SciTech Connect

Determination of the Bragg peak position in proton therapy requires accurate knowledge of the electron density and ratio of effective atomic number and mass (Z/A) of the body tissues traversed. While the Z/A ratio is fairly constant for human tissues, the density of tissues varies significantly. One possibility to obtain accurate electron density information of tissues is to use protons of sufficient energy to penetrate the patient and measure their energy loss. From these transmission measurements, it is possible to reconstruct a three-dimensional map of electron densities using algebraic techniques. The interest in proton computed tomography (pCT) has considerably increased in recent years due to the more common use of proton accelerators for cancer treatment world-wide and a modern design concept based on current high-energy physics technology has been suggested. This contribution gives a status update on the pCT project carried out by the pCT Collaboration, a group of institutions sharing interest and expertise in the development of pCT. We will present updated imaging data obtained with a small pCT prototype developed in collaboration with the Santa Cruz Institute of Particle Physics and installed on the proton research beam line at Loma Linda University Medical Center. We will discuss hardware decisions regarding the next-generation pCT scanner, which will permit scanning of head-sized objects. Progress has also been made in the formulation of the most likely path of protons through an object and parallelizable iterative reconstruction algorithms that can be implemented on general-purpose commodity graphics processing units. Finally, we will present simulation studies for utilizing pCT technology for on-line proton dose verification and tumor imaging with positron emission tomography (PET)

Bashkirov, Vladimir; Schulte, Reinhard; Coutrakon, George [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA 92354 (United States); Erdelyi, Bela; Wong, Kent [Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States); Sadrozinski, Hartmut [Santa Cruz Institute of Particle Physics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Penfold, Scott; Rosenfeld, Anatoly [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); McAllister, Scott; Schubert, Keith [Department of Computer Science and Engineering, California State University San Bernardino, San Bernardino, CA 92407 (United States)

2009-03-10

145

SYNCHROTRONS AND BEAMLINES FOR PROTON RADIOGRAPHY  

Microsoft Academic Search

A 50 GeV accelerator complex for dynamic proton radiography, including a linac, synchrotron, and multiple isochronous beamlines is described, and critical technology development is outlined. Transmission radiographic images with high spatial and temporal resolution can be made when proton pulses illuminate an imploding test object that is placed in the object plane of a point-to-point magnetic quadrupole imaging system. From

F. Neri; H. A. Thiessen; P. L. Walstrom; Max Momentum

1998-01-01

146

Magnetic Resonance Imaging of Subchondral Bone Marrow Lesions in Association with Osteoarthritis  

PubMed Central

Objectives This nonsystematic literature review provides an overview of magnetic resonance imaging (MRI) of subchondral bone marrow lesions (BMLs) in association with osteoarthritis (OA), with particular attention to the selection of MRI sequences and semiquantitative scoring systems, characteristic morphology, and differential diagnosis. Histologic basis, natural history, and clinical significance are also briefly discussed. Methods PubMed was searched for articles published up to 2011, using the keywords bone marrow lesion, osteoarthritis, magnetic resonance imaging, bone marrow edema, histology, pain, and subchondral. Results BMLs in association with OA correspond to fibrosis, necrosis, edema, and bleeding of fatty marrow as well as abnormal trabeculae on histopathology. Lesions may fluctuate in size within a short time and are associated with the progression of articular cartilage loss and fluctuation of pain in knee OA. The characteristic subchondral edema-like signal intensity of BMLs should be assessed using T2-weighted, proton density-weighted, intermediate-weighted fat-suppressed fast spin echo or short tau inversion recovery. Several semiquantitative scoring systems are available to characterize and grade the severity of BMLs. Quantitative approaches have also been introduced. Differential diagnoses of degenerative BMLs include a variety of traumatic or nontraumatic pathologies that may appear similar to OA-related BMLs on MRI. Conclusions Subchondral BMLs are a common imaging feature of OA with clinical significance and typical signal alteration patterns, which can be assessed and graded by semiquantitative scoring systems using sensitive MRI sequences.

Xu, Li; Hayashi, Daichi; Roemer, Frank W.; Felson, David T.; Guermazi, Ali

2013-01-01

147

Proton decay theory  

SciTech Connect

Topics include minimal SU(5) predictions, gauge boson mediated proton decay, uncertainties in tau/sub p/, Higgs scalar effects, proton decay via Higgs scalars, supersymmetric SU(5), dimension 5 operators and proton decay, and Higgs scalars and proton decay. (WHK)

Marciano, W.J.

1983-01-01

148

Gd(III) complexes as contrast agents for magnetic resonance imaging: a proton relaxation enhancement study of the interaction with human serum albumin  

Microsoft Academic Search

The non-covalent interaction between human serum albumin (HSA) and DOTA-like Gd(III) complexes containing hydrophobic benzyloxymethyl\\u000a (BOM) substituents has been thoroughly investigated by measuring the solvent proton relaxation rates of their aqueous solutions.\\u000a The binding association constants (K\\u000a A) to HSA are directly related to the number of hydrophobic substituents present on the surface of the complexes. Furthermore,\\u000a an estimation of

Silvio Aime; Mauro Botta; Mauro Fasano; Simonetta Geninatti Crich; Enzo Terreno

1996-01-01

149

Synchrotron based proton drivers  

SciTech Connect

Proton drivers are the proton sources that produce intense short proton bunches. They have a wide range of applications. This paper discusses the proton drivers based on high-intensity proton synchrotrons. It gives a review of the high-intensity proton sources over the world and a brief report on recent developments in this field in the U.S. high-energy physics (HEP) community. The Fermilab Proton Driver is used as a case study for a number of challenging technical design issues.

Weiren Chou

2002-09-19

150

Proton Therapy - Accelerating Protons to Save Lives  

SciTech Connect

In 1946, physicist Robert Wilson first suggested that protons could be used as a form of radiation therapy in the treatment of cancer because of the sharp drop-off that occurs on the distal edge of the radiation dose. Research soon confirmed that high-energy protons were particularly suitable for treating tumors near critical structures, such as the heart and spinal column. The precision with which protons can be delivered means that more radiation can be deposited into the tumor while the surrounding healthy tissue receives substantially less or, in some cases, no radiation. Since these times, particle accelerators have continuously been used in cancer therapy and today new facilities specifically designed for proton therapy are being built in many countries. Proton therapy has been hailed as a revolutionary cancer treatment, with higher cure rates and fewer side effects than traditional X-ray photon radiation therapy. Proton therapy is the modality of choice for treating certain small tumors of the eye, head or neck. Because it exposes less of the tissue surrounding a tumor to the dosage, proton therapy lowers the risk of secondary cancers later in life - especially important for young children. To date, over 80,000 patients worldwide have been treated with protons. Currently, there are nine proton radiation therapy facilities operating in the United States, one at the Hampton University Proton Therapy Institute. An overview of the treatment technology and this new center will be presented.

Keppel, Cynthia (Hampton University Proton Therapy) [Hampton University Proton Therapy

2011-10-25

151

First results on proton radiography with nuclear emulsion detectors  

NASA Astrophysics Data System (ADS)

We propose an innovative method for proton radiography based on nuclear emulsion film detectors, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. For this purpose, nuclear emulsion films interleaved with tissue equivalent absorbers can be used to reconstruct proton tracks with very high accuracy. This is performed through a fully automated scanning procedure employing optical microscopy, routinely used in neutrino physics experiments. Proton radiography can be used in proton therapy to obtain direct information on the average tissue density for treatment planning optimization and to perform imaging with very low dose to the patient. The first prototype of a nuclear emulsion based detector has been conceived, constructed and tested with a therapeutic proton beam. The first promising experimental results have been obtained by imaging simple phantoms.

Braccini, S.; Ereditato, A.; Kreslo, I.; Moser, U.; Pistillo, C.; Studer, S.; Scampoli, P.; Coray, A.; Pedroni, E.

2010-09-01

152

Design study of an in situ PET scanner for use in proton beam therapy  

Microsoft Academic Search

Proton beam therapy can deliver a high radiation dose to a tumor without significant damage to surrounding healthy tissue or organs. One way of verifying the delivered dose distribution is to image the short-lived positron emitters produced by the proton beam as it travels through the patient. A potential solution to the limitations of PET imaging in proton beam therapy

S. Surti; W. Zou; M. E. Daube-Witherspoon; J. McDonough; J. S. Karp

2011-01-01

153

Proton shadow camera using CR-39 track detectors  

SciTech Connect

We have developed a capability for imaging proton sources of moderate energy (6 MeV), with moderate spatial resolution (approx. = 9 ..mu..m), as a diagnostic for laser fusion research. Our technique involves the use of Fresnel zone plate coded imaging coupled with nuclear track detectors (CR-39). We report on a series of test experiments in which a zone plate shadow camera successfully produced images of a proton source distribution. The zone plate shadow patterns were optically reconstructed in higher order producing diffraction-limited point response images with FWHM values of approx. = 9 ..mu..m for a 6 MeV proton source.

Stone, G.F.; Ceglio, N.M.

1983-09-01

154

-delayed proton emission branches in 43Cr  

SciTech Connect

The + decay of very neutron-deficient 43Cr was studied by means of an imaging time projection chamber that allowed recording tracks of charged particles. Events of -delayed emission of one, two, and three protons were clearly identified. The absolute branching ratios for these channels were determined to be (81 4)%, (7.1 0.4)%, and (0.08 0.03)%, respectively. 43Cr is thus established as the second case in which the -3p decay occurs. Although the feeding to the proton-bound states in 43V is expected to be negligible, the large branching ratio of (12 4)% for decays without proton emission is found.

Pomorski, M. [University of Warsaw; Miernik, K. [University of Warsaw; Dominik, W. [University of Warsaw; Janas, Z. [University of Warsaw; Pfutzner, M. [University of Warsaw; Bingham, C. R. [University of Tennessee, Knoxville (UTK); Czyrkowski, H. [University of Warsaw; Cwiok, Mikolaj [Warsaw University; Darby, Iain [University of Tennessee, Knoxville (UTK); Dabrowski, Ryszard [Warsaw University; Ginter, T. N. [Michigan State University, East Lansing; Grzywacz, Robert Kazimierz [ORNL; Karny, M. [University of Warsaw; Korgul, A. [University of Warsaw; Kusmierz, W. [University of Warsaw; Liddick, Sean [University of Tennessee, Knoxville (UTK); Rajabali, M. M. [University of Tennessee, Knoxville (UTK); Rykaczewski, Krzysztof Piotr [ORNL; Stolz, A. [Michigan State University, East Lansing

2011-01-01

155

Comparing proton density and turbo spin echo T2 weighted static sequences with dynamic half-Fourier single-shot TSE pulse sequence at 3.0?T in diagnosis of temporomandibular joint disorders: a prospective study.  

PubMed

Objectives: The aim of this prospective study was to compare dynamic and static sequences in the evaluation of temporomandibular joint disorders using a 3.0?-T imaging unit. Methods: 194 patients were evaluated by static (double echo proton density weighted/turbo spin echo T2 weighted sequences) and dynamic (half-Fourier single-shot turbo spin echo sequences)imaging. Two radiologists evaluated in consensus the quality of images, the disc position and morphological alterations. The Kendall rank correlation coefficient (?-b) was used to compare the qualitative rating between static and dynamic sequences. Cohen's kappa coefficient (k) was used to assess the agreement of disc position and morphological alterations between both sequences. The intraclass correlation coefficient was used to calculate the intraobserver variability. The significance was set at p???0.05. Results: The correlation between both sequences in the qualitative evaluation was ?-b?=?0.632. The agreement between both techniques in the evaluation of disc position was k?=?0.856. The agreement between both techniques in assessing the morphological alterations was k?=?0.487. In the static sequences, the intraclass correlation coefficient was 0.915 in the qualitative evaluation, 0.873 in the evaluation of disc position and 0.934 in the assessment of morphological alterations. In the dynamic sequences, the intraclass correlation coefficient was 0.785 in the qualitative evaluation, 0.935 in the evaluation of disc position and 0.826 in the assessment of morphological alterations. Conclusions: Static imaging remains the gold standard in the evaluation of the temporomandibular joint. Dynamic imaging is a valuable tool that can provide additional information about topographic changes in the disc-condyle relationship. PMID:24720606

Cassetta, M; Barchetti, F; Pranno, N; Marini, M

2014-03-01

156

Treatment planning for conformal proton radiation therapy.  

PubMed

Clinical results from various trials have demonstrated the viability of protons in radiation therapy and radiosurgery. This has motivated a few large medical centers to design and build expensive hospital based proton facilities based proton facilities (current cost estimates for a proton facility is around 100 million US dollars). Until this development proton therapy was done using retrofitted equipment originally designed for nuclear experiments. There are presently only three active proton therapy centers in the United States, 22 worldwide. However, more centers are under construction and being proposed in the US and abroad. The important difference between proton and x-ray therapy is in the dose distribution. X-rays deposit most of their dose at shallow depths of a few centimeters with a gradual decay with depth in the patient. Protons deliver most of their dose in the Bragg peak, which can be delivered at most clinically required depths followed by a sharp fall-off. This sharp falloff makes protons sensitive to variations in treatment depths within patients. Treatment planning incorporates all the knowledge of protons into a process, which allows patients to be treated accurately and reliably. This process includes patient immobilization, imaging, targeting, and modeling of planned dose distributions. Although the principles are similar to x-ray therapy some significant differences exist in the planning process, which described in this paper. Target dose conformality has recently taken on much momentum with the advent of intensity modulated radiation therapy (IMRT) with photon beams. Proton treatments provide a viable alternative to IMRT because they are inherently conformal avoiding normal tissue while irradiating the intended targets. Proton therapy will soon bring conformality to a new high with the development of intensity modulated proton therapy (IMPT). Future challenges include keeping the cost down, increasing access to conventional proton therapy as well as the clinical implementation of IMPT. Computing advances are making Monte Carlo techniques more accessible to treatment planning for all modalities including proton therapy. This technique will allow complex delivery configurations to be properly modeled in a clinical setting. PMID:14529304

Bussière, Mark R; Adams, Judith A

2003-10-01

157

What's In a Proton?  

SciTech Connect

Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

Brookhaven Lab

2009-07-08

158

What's In a Proton?  

ScienceCinema

Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

159

What's In a Proton?  

ScienceCinema

Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

Brookhaven Lab

2010-01-08

160

ChemTeacher: Proton  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Proton page includes resources for teaching students about protons.

2011-01-01

161

Diffusion-Weighted Imaging and Proton Magnetic Resonance Spectroscopy in Perinatal Hypoxic-Ischemic Encephalopathy: Association With Neuromotor Outcome at 18 Months of Age  

Microsoft Academic Search

We evaluated early diffusion-weighted imaging findings, the quantitative apparent diffusion coefficient, and magnetic resonance spectroscopy (the presence of lactate and ratios of N-acetylaspartate to total creatine and choline to total creatine) in the prediction of the 18-month neuromotor outcome of term newborns with hypoxic-ischemic encephalopathy. Conventional T1- and T2-weighted and diffusion-weighted imaging was performed in 20 asphyxiated term newborns, with

Pek-Lan Kliong; Catherine Tse; Ivan Y. C. Wong; Barbara C. C. Lam; Pik-To Cheung; Winnie H. S. Goh; Ngai Shan Kwong; Gaik-Cheng Ooi

2004-01-01

162

The Schwarzschild Proton  

Microsoft Academic Search

We review our model of a proton that obeys the Schwarzschild condition. We find that only a very small percentage (~10-39%) of the vacuum fluctuations available within a proton volume need be cohered and converted to mass-energy in order for the proton to meet the Schwarzschild condition. This proportion is equivalent to that between gravitation and the strong force where

Nassim Haramein; Nassim

2010-01-01

163

Magnetic optics for proton radiography  

SciTech Connect

High energy protons of 10 to 50 GeV can be used to radiograph dense objects. Because the transmitted beam particles undergo multiple coulomb scattering (MCS) in the object, a magnetic lens system is used to focus the particles exiting each point of the object onto a distant image plane. Without the lens, the MCS would seriously blur the radiographic image. Correlations can be introduced in the illuminating beam to cancel a major part of the chromatic and geometric aberrations in the lens, while providing locations inside the lens where the rays are sorted by MCS angle. This allows the introduction of angle cut apertures to aid material identification. The requirement for a matched multistage lens system with successively smaller angle-cut apertures leads to the use of minus-identity ({minus}I) lenses, in which the angle sorting is in the longitudinal mid plane of the lens, and the exit beam correlations are the same as the input correlations. A single stage {minus}I lens has been successfully tested at Brookhaven with 10-GeV protons and another is being used in dynamic experiments with 0.8-GeV protons at Los Alamos. The resolution achievable at higher energies is briefly surveyed.

Mottershead, C.T.; Zumbro, J.D.

1997-10-01

164

Note: A new angle-resolved proton energy spectrometer  

SciTech Connect

In typical laser-driven proton acceleration experiments Thomson parabola proton spectrometers are used to measure the proton spectra with very small acceptance angle in specific directions. Stacks composed of CR-39 nuclear track detectors, imaging plates, or radiochromic films are used to measure the angular distributions of the proton beams, respectively. In this paper, a new proton spectrometer, which can measure the spectra and angular distributions simultaneously, has been designed. Proton acceleration experiments performed on the Xtreme light III laser system demonstrates that the spectrometer can give angle-resolved spectra with a large acceptance angle. This will be conductive to revealing the acceleration mechanisms, optimization, and applications of laser-driven proton beams.

Zheng, Y.; Su, L. N.; Liu, M.; Liu, B. C.; Shen, Z. W.; Fan, H. T.; Li, Y. T.; Chen, L. M.; Lu, X.; Ma, J. L.; Wang, W. M.; Wang, Z. H.; Wei, Z. Y. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)] [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China) [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory for Laser Plasmas (MoE) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

2013-09-15

165

Imaging acute ischemic tissue acidosis with pH-sensitive endogenous amide proton transfer (APT) MRI - Correction of tissue relaxation and concomitant RF irradiation effects toward mapping quantitative cerebral tissue pH  

PubMed Central

Amide proton transfer (APT) MRI is sensitive to ischemic tissue acidosis and has been increasingly used as a research tool to investigate disrupted tissue metabolism during acute stroke. However, magnetization transfer asymmetry (MTRasym) analysis is often used for calculating APT contrast, which only provides pH-weighted images. In addition to pH- dependent APT contrast, in vivo MTRasym is subject to a baseline shift (?MTR?asym) attributable to the slightly asymmetric magnetization transfer (MT) effect. Additionally, APT contrast approximately scales with T1 relaxation time. Tissue relaxation time may also affect the experimentally obtainable APT contrast via saturation efficiency and RF spillover effects. In this study, we acquired perfusion, diffusion, relaxation and pH-weighted APT MRI data, and spectroscopy (MRS) in an animal model of acute ischemic stroke. We modeled in vivo MTRasym as a superposition of pH-dependent APT contrast and a baseline shift ?MTR?asym (i.e., MTRasym=APTR(pH) + ?MTR?asym), and quantified tissue pH. We found pH of the contralateral normal tissue to be 7.03 ± 0.05 and the ipsilateral ischemic tissue pH was 6.44 ± 0.24, which correlated with tissue perfusion and diffusion rates. In summary, our study established an endogenous and quantitative pH imaging technique for improved characterization of ischemic tissue acidification and metabolism disruption.

Sun, Phillip Zhe; Wang, Enfeng; Cheung, Jerry S

2011-01-01

166

MR Imaging Characteristics of Tuberculous Spondylitis vs Vertebral Osteomyelitis  

Microsoft Academic Search

Retrospective evaluation was made of four patients with tuberculous spondylitis wbe had been studied by MR with Ti- and T2-weighted images in the sagittal plane and spin-density-weighted images in the axial plane. Evaluation was made of the distribution of abnormal signals within the body and posterior elements of the vertebrae, the intervertebral disk, and the associated paraspinal and epidural areas.

Alison S. Smith; Meredith A. Weinstein; Akira Mizushima; Bret Coughlin; Stephen P. Hayden; Milton M. Lakin; Charles F. Lanzieri

167

Influence of X Chromosome and Hormones on Human Brain Development: A Magnetic Resonance Imaging and Proton Magnetic Resonance Spectroscopy Study of Turner Syndrome  

Microsoft Academic Search

Background: Women with Turner syndrome (TS; 45,X) lack a normal second X chromosome, and many are prescibed exogenous sex and growth hormones (GH). Hence, the allow its an opportunity to investigate genetic and endocrine influences on brain development. Methods: We examined brain anatomy and metabolism in 27 adult monosomic TS women and 21 control subjects with volumetric magnetic resonance imaging

William J. Cutter; Eileen M. Daly; Dene M. W. Robertson; Xavier A. Chitnis; Therese A. M. J. van Amelsvoort; Andrew Simmons; Virginia W. K. Ng; Benjamin S. Williams; Phillip Shaw; Gerard S. Conway; David H. Skuse; David A. Collier; Michael Craig; Declan G. M. Murphy

2006-01-01

168

Quantitative proton radiography of an animal patient  

NASA Astrophysics Data System (ADS)

Images (with a spatial resolution of 1 mm x 1mm) were produced both, with range and range dilution information of the protons passing through a dog. The radiographies were taken prior to a proton radiotherapy treatment of a nasal tumor, while the dog patient was under anesthetics. The first image was created by calculating the mean range of the protons detected in each pixel. This image was compared to calculations of the treatment planning system based on a CT-scan of the dog. Errors in the calculated range could be detected. The second image was produced by calculating the width of the range spectrum in each pixel. This value is a measure of the dilution of the range due to tissue inhomogeneities. The dilution image can be used to indicate critical situations during proton therapy, to determine the safety margin around the tumor volume, or to optimise treatment. In a preliminary analysis of the radiography data we found range uncertainty and range dilution effects in the order of up to 10 mm.

Schneider, Uwe; Dellert, Matthias; Pedroni, Eros; Pemler, Peter; Besserer, Juergen; Moosburger, Martin; Theiler, Prisca; Kaser-Hotz, Barbara

2003-06-01

169

Electromagnetic proton cyclotron instability: Proton velocity distributions  

NASA Astrophysics Data System (ADS)

The hot (Th~10 keV) protons of the outer magnetosphere are frequently observed to have T?/T?>1, where the subscripts denote directions relative to the background magnetic field. This anisotropy leads to the growth of the electromagnetic proton cyclotron anisotropy instability, which implies two concise scaling relations: an upper bound on T?h/T?h and an expression for the apparent temperature of warm (Tw~10 eV) protons heated by this instability. One-dimensional hybrid simulations of this instability in a homogeneous plasma have been used to examine the velocity distribution response of both hot and warm protons. Results are that the enhanced fluctuations from this instability not only preserve the initially bi-Maxwellian character of a hot proton distribution but also drive a hot distribution which is initially nongyrotropic rapidly toward the gyrotropic condition. These results further support the validity of the hot proton temperature anisotropy upper bound. Although wave-particle interactions yield nongyrotropic fw(v?) distributions, the fw(v?) remain Maxwellian-like as they are heated by the enhanced fluctuations.

Gary, S. Peter; Vazquez, Victor M.; Winske, Dan

1996-06-01

170

Proton-counting radiography for proton therapy: a proof of principle using CMOS APS technology.  

PubMed

Despite the early recognition of the potential of proton imaging to assist proton therapy (Cormack 1963 J. Appl. Phys. 34 2722), the modality is still removed from clinical practice, with various approaches in development. For proton-counting radiography applications such as computed tomography (CT), the water-equivalent-path-length that each proton has travelled through an imaged object must be inferred. Typically, scintillator-based technology has been used in various energy/range telescope designs. Here we propose a very different alternative of using radiation-hard CMOS active pixel sensor technology. The ability of such a sensor to resolve the passage of individual protons in a therapy beam has not been previously shown. Here, such capability is demonstrated using a 36 MeV cyclotron beam (University of Birmingham Cyclotron, Birmingham, UK) and a 200 MeV clinical radiotherapy beam (iThemba LABS, Cape Town, SA). The feasibility of tracking individual protons through multiple CMOS layers is also demonstrated using a two-layer stack of sensors. The chief advantages of this solution are the spatial discrimination of events intrinsic to pixelated sensors, combined with the potential provision of information on both the range and residual energy of a proton. The challenges in developing a practical system are discussed. PMID:24785680

Poludniowski, G; Allinson, N M; Anaxagoras, T; Esposito, M; Green, S; Manolopoulos, S; Nieto-Camero, J; Parker, D J; Price, T; Evans, P M

2014-06-01

171

Proton-counting radiography for proton therapy: a proof of principle using CMOS APS technology  

NASA Astrophysics Data System (ADS)

Despite the early recognition of the potential of proton imaging to assist proton therapy (Cormack 1963 J. Appl. Phys. 34 2722), the modality is still removed from clinical practice, with various approaches in development. For proton-counting radiography applications such as computed tomography (CT), the water-equivalent-path-length that each proton has travelled through an imaged object must be inferred. Typically, scintillator-based technology has been used in various energy/range telescope designs. Here we propose a very different alternative of using radiation-hard CMOS active pixel sensor technology. The ability of such a sensor to resolve the passage of individual protons in a therapy beam has not been previously shown. Here, such capability is demonstrated using a 36 MeV cyclotron beam (University of Birmingham Cyclotron, Birmingham, UK) and a 200 MeV clinical radiotherapy beam (iThemba LABS, Cape Town, SA). The feasibility of tracking individual protons through multiple CMOS layers is also demonstrated using a two-layer stack of sensors. The chief advantages of this solution are the spatial discrimination of events intrinsic to pixelated sensors, combined with the potential provision of information on both the range and residual energy of a proton. The challenges in developing a practical system are discussed.

Poludniowski, G.; Allinson, N. M.; Anaxagoras, T.; Esposito, M.; Green, S.; Manolopoulos, S.; Nieto-Camero, J.; Parker, D. J.; Price, T.; Evans, P. M.

2014-06-01

172

MR Spectroscopic Changes in the Rat Hippocampus following Proton Radiosurgery  

Microsoft Academic Search

Purpose: To identify MR spectroscopic changes in the rat hippocampus following proton radiosurgery. Methods and Materials: A group of 12 rats were treated with Bragg peak proton beam irradiation involving the right hippocampus. Single doses of 30 CGE, 50 CGE, 70 CGE, 90 CGE were delivered to groups of 3 animals using single fraction technique. Animals were imaged using a

J. D. Rabinov; L. L. Cheng; P. L. Lee; J. L. Brisman; J. S. Loeffler; A. J. Cole; G. R. Cosgrove; M. R. Bussiere; T. Chaves; R. G. Gonzalez

2006-01-01

173

Protonation Sites in Chemically Amplified Resists for Electron-Beam Lithography  

NASA Astrophysics Data System (ADS)

In chemically amplified resists that utilize acid-catalytic reactions for pattern formation, proton dynamics is important from the viewpoints of the insoluble layer formation due to acid loss, the resolution decrease due to acid diffusion, and the image quality improvement due to base-quencher effects. For electron-beam lithography, the protons and anions of the acid are initially generated at different places. Protons migrate in the resist matrix toward counter anions, attracted by the opposite electric charges. However, the details of proton migration are still unclear. In this study, we investigated proton quenching in poly(4-hydroxystyrene) films using base quenchers with different proton affinities. When the proton affinity of the base quencher was increased, the equimolecular proton adduct of the acid-sensitive dye was quenched without postexposure bake. Although the proton affinity is a gas-phase value, the quenching effect correlated well with the proton affinity.

Natsuda, Kenichiro; Kozawa, Takahiro; Okamoto, Kazumasa; Tagawa, Seiichi

2006-12-01

174

Influence of proton beam Coulomb explosion in laser proton acceleration  

NASA Astrophysics Data System (ADS)

To further understand proton acceleration driven by the interaction between ultra-intense laser pulse and foil targets, the influence of proton beam Coulomb explosion has been analyzed theoretically and investigated using two-dimensional particle-in-cell (2D-PIC) simulations. Employing different proton layer sizes in the simulations, it is found that proton beam Coulomb explosion plays an important role on proton acceleration, in particular on proton cut off energy. Proton dynamics including the effect of both sheath field and proton beam Coulomb explosion was proposed and discussed in detail. This work may serve to improve the understanding of proton acceleration driven by intense laser-foil interactions.

Yu, Jinqing; Jin, Xiaolin; Zhou, Weimin; Gu, Yuqiu; Zhan, Rongxin; Zhao, Zongqing; Cao, Leifeng; Li, Bin

2013-12-01

175

Evaluation of fatty liver by using in-phase and opposed-phase MR images and in-vivo proton MR spectroscopy  

NASA Astrophysics Data System (ADS)

The purpose of this study was to evaluate the necessity of in-phase and opposed-phase MR images and their correlations with weight, the aspartate aminotransferase/alanine aminotransferase (AST/ALT) value, and age. Magnetic resonance spectroscopy (MRS) was used as a reference in this study. We selected 68 people as subjects, among which 14 were volunteers with normal AST/ALT values ( <40/35 U/L) on a liver function study and 54 were non-alcoholic fatty liver patients for whom ultrasonic images had been obtained within 3 months of the study. In this study, the liver was more enhanced than the spleen or kidney. When the Eq. (3) formula was applied to normal volunteers, the difference between the in-phase and the opposed-phase images was -3.54 ± 12.56. The MRS study result showed a high sensitivity of 96.6% and a specificity of 100% ( p = 0.000) when the cutoff value was 20%. Furthermore, this result showed a high sensitivity of 94% and a specificity of 80% with a similar cutoff when the Eq. (2) formula was applied to non-alcoholic fatty liver patients ( p = 0.000). The MRS study revealed a strong correlation between normal volunteers and non-alcoholic fatty liver patients (r = 0.59, p = 0.04). The correlations between AST/ALT and Eq. (3) (r = 0.45, p = 0.004), age and Eq. (3) (r = 0.73, p = 0.03), and weight and Eq. (3) (r = 0.77, p = 0.000) values were all statistically significant. In the case of non-alcoholic liver disease, MRS was found to be significantly correlated with Eq. (1) (r = 0.39, p = 0.002), Eq. (2) (r = 0.68, p = 0.04), Eq. (3) (r = 0.67, p = 0.04), and AST/ALT (r = 0.77, p = 0.000). In conclusion, in-phase and opposed-phase images can help to distinguish a normal liver from a fatty liver in order to identify non-alcoholic fatty liver patients. The intensity difference between the in-phase and opposed-phase MR signals showed valuable correlations with respect to weight, AST/ALT value, and age, with all values being above the mild lipid value (r = 0.3).

Lee, Jae-Seung; Im, In-Chul; Goo, Eun-Hoe; Park, Hyong-Hu; Kwak, Byung-Joon

2012-12-01

176

Proton-proton reaction theory with proton polarizability.  

National Technical Information Service (NTIS)

The effect of proton polarizability in pp-scattering and in pp-reaction is considered with including a polarization potential into pp-interaction. Convenient low-energy representations of the pp-scattering function are derived within the variable phase ap...

V. V. Pupyshev O. P. Solovtsova

1989-01-01

177

Charge transfer efficiency in proton damaged CCD's  

Microsoft Academic Search

We have performed detailed measurements of the charge transfer efficiency (CTE) in a thinned, backside-illuminated imaging charge-coupled device (CCD). The device had been damaged in three separate sections by proton radiation typical of that which a CCD would receive in space-borne experiments, nuclear imaging, or particle detection. We examined CTE as a function of signal level, temperature, and radiation dose.

Tim Hardy; R. Murowinski; M. J. Deen

1998-01-01

178

Shapes of the proton  

NASA Astrophysics Data System (ADS)

A model proton wave function, constructed using Poincaré invariance and constrained by recent electromagnetic form factor data, is used to study the shape of the proton. Spin-dependent quark densities are defined as matrix elements of density operators in proton states of definite polarization, and shown to have an infinite variety of nonspherical shapes. For high momentum quarks with spin parallel to that of the proton, the shape resembles that of a peanut, but for quarks with antiparallel spin the shape is that of a bagel.

Miller, Gerald A.

2003-08-01

179

Images.  

ERIC Educational Resources Information Center

The theme of this month's issue is "Images"--from early paintings and statuary to computer-generated design. Resources on the theme include Web sites, CD-ROMs and software, videos, books, and others. A page of reproducible activities is also provided. Features include photojournalism, inspirational Web sites, art history, pop art, and myths. (AEF)

Barr, Catherine, Ed.

1997-01-01

180

ADvanced IMage Algebra (ADIMA): a novel method for depicting multiple sclerosis lesion heterogeneity, as demonstrated by quantitative MRI  

PubMed Central

Background: There are modest correlations between multiple sclerosis (MS) disability and white matter lesion (WML) volumes, as measured by T2-weighted (T2w) magnetic resonance imaging (MRI) scans (T2-WML). This may partly reflect pathological heterogeneity in WMLs, which is not apparent on T2w scans. Objective: To determine if ADvanced IMage Algebra (ADIMA), a novel MRI post-processing method, can reveal WML heterogeneity from proton-density weighted (PDw) and T2w images. Methods: We obtained conventional PDw and T2w images from 10 patients with relapsing–remitting MS (RRMS) and ADIMA images were calculated from these. We classified all WML into bright (ADIMA-b) and dark (ADIMA-d) sub-regions, which were segmented. We obtained conventional T2-WML and T1-WML volumes for comparison, as well as the following quantitative magnetic resonance parameters: magnetisation transfer ratio (MTR), T1 and T2. Also, we assessed the reproducibility of the segmentation for ADIMA-b, ADIMA-d and T2-WML. Results: Our study’s ADIMA-derived volumes correlated with conventional lesion volumes (p < 0.05). ADIMA-b exhibited higher T1 and T2, and lower MTR than the T2-WML (p < 0.001). Despite the similarity in T1 values between ADIMA-b and T1-WML, these regions were only partly overlapping with each other. ADIMA-d exhibited quantitative characteristics similar to T2-WML; however, they were only partly overlapping. Mean intra- and inter-observer coefficients of variation for ADIMA-b, ADIMA-d and T2-WML volumes were all < 6 % and < 10 %, respectively. Conclusion: ADIMA enabled the simple classification of WML into two groups having different quantitative magnetic resonance properties, which can be reproducibly distinguished.

Tozer, Daniel J; Schmierer, Klaus; Chard, Declan T; Anderson, Valerie M; Altmann, Daniel R; Miller, David H; Wheeler-Kingshott, Claudia AM

2013-01-01

181

Design and construction of the 1{sup st} proton CT scanner  

SciTech Connect

This paper discusses the design and operation of the 1{sup st} proton CT scanner for 3D imaging. Reduction of proton range uncertainties and improved dose accuracy in the patient for treatment planning are central goals. A central CT slice acquired by reconstruction of 134 million proton tracks through a 14 cm spherical polystyrene phantom with high and low density inserts is presented.

Coutrakon, G.; Rykalin, V. [Dept. of Physics, Northern Illinois Univ., DeKalb, IL 60115 (United States); Bashkirov, V.; Hurley, F.; Schulte, R. [Dept. of Radiation Medicine, Loma Linda Univ. Med. Ctr., Loma Linda, CA 92354 (United States); Johnson, R.; Sadrozinski, H. [Santa Cruz Institute of Particle Physics, Univ. of California at Santa Cruz, CA 95064 (United States)

2013-04-19

182

Young Investigator Award presentation at the 13th Annual Meeting of the ESMRMB, September 1996, Prague. A proton-electron double-resonance imaging apparatus with simultaneous multiple electron paramagnetic resonance irradiation at 10 mT.  

PubMed

The detection of free radicals in vivo is very important for the study of many physiologic and pathologic conditions. Free radicals have been implicated in a number of diseases such as ischemia, inflammation, kidney damage, and cancer. Proton-electron double-resonance imaging (PEDRI) allows the indirect detection of free radicals via the Overhauser effect. Nitroxide free radicals used for in vivo PEDRI studies present spectra with two or three lines, but most PEDRI experiments performed to date have used only single-line electron paramagnetic resonance (EPR) irradiation. There is theoretical evidence that simultaneous irradiation of multiple EPR transitions could increase the maximum achievable PEDRI enhancement. From the experimental point of view, this requires the combined use of a suitable multiple-frequency EPR source and a multiple-tuned EPR resonator. A novel radiofrequency (RF) triple-tuned loop-gap resonator for use in PEDRI has recently been developed, and dynamic nuclear polarization (DNP) data were reported. In the present study we describe a new PEDRI apparatus, equipped with a triple-tuned resonator, that is suitable for simultaneous double- or triple-EPR irradiation of nitroxide free radicals. In particular, the details of the EPR hardware used to generate the two or three EPR frequencies are given, and PEDRI images obtained with simultaneous multiple EPR irradiation are shown. Moreover, DNP experimental results showing the increase of the enhancement as a function of the EPR power for single and simultaneous double EPR irradiation are presented. The main goal of this apparatus is to improve the sensitivity and/or to reduce EPR irradiation power in a PEDRI experiment. This is likely to be particularly important in future biologic applications of PEDRI where the applied power must be optimized to reduce sample heating. PMID:9220407

Alecci, M; Lurie, D J; Nicholson, I; Placidi, G; Sotgiu, A

1996-01-01

183

Relativistic description of proton-proton bremsstrahlung  

NASA Astrophysics Data System (ADS)

We investigate the influence of negative-energy states in proton-proton bremsstrahlung in a fully relativistic framework using the t-matrix of Fleischer and Tjon. The contribution from negative-energy states in the single-scattering diagrams are found to be large, indicating that relativistic effects are sizable. The rescattering contribution compensates some of the effect, but at higher photon energies we find that the relativistic contributions become increasingly more important. The cancellation found at lower energies is shown to be due to a low-energy theorem.

Martinus, G. H.; Scholten, O.; Tjon, J. A.

1997-02-01

184

Investigation of Proton Focusing and Conversion Efficiency for Proton Fast Ignition  

NASA Astrophysics Data System (ADS)

Recent advances in generating high energy (> 50 MeV) protons from intense laser-matter interactions has opened up new areas of research, with applications in radiography, high energy density physics, and ion-proton beam fast ignition (FI). The ability to focus the proton beam has made these applications more attractive. Fast ignition (FI) is an evolved concept of conventional inertial confinement fusion (ICF). In proton FI, a collimated beam of protons is used to deliver the necessary ignition energy to the compressed Deuterium-Tritium (DT) fuel capsule instead of the original concept of a beam composed of relativistic electrons. In cone-guided FI, a cone is embedded into the side of the fuel capsule where the proton source foil is placed within the cone. The cone provides a clear path to the dense core and protects the proton source foil from radiation during the compression of the capsule. The proton source foil is a segment of a hemispherical shell target used to help focus the proton beam to the core to spark ignition. The viability of proton FI requires focusing of the generated proton beam to a 40 mum spot at the compressed fuel and a laser to proton conversion efficiency of ˜15%. Here, proton focusing and the laser to proton conversion efficiency are investigated using flat foils and hemispherical shell targets. Experiments were conducted on the 200 TW short pulse laser at Los Alamos Laboratory. The 1053 nm laser pulse delivered 70--80 J on target in 500--600 fs focused by an f/8 parabolic mirror. The generated proton beam from the target was examined by placing a mesh downstream of the target, which the proton beam would pass though and then imaged with a pack of radiochromic film (RCF). A 3D ray-tracing technique was developed to determine the focal position and focal spot size of the generated proton beam by tracing the proton trajectories from the image of the mesh collected by the RCF back through the mesh to the central axis. The focal position calculated from the ray-tracing technique for the flat foils resulted in a real focus, contrasting the convention wisdom of a virtual focus. Investigation of the proton expansion from flat foils established that initially the protons are accelerated normal to the surface, due to the fact that the electrostatic sheath field generated by the escaping hot electrons is only a few microns beyond the rear surface of the foil. As time progresses and more electrons are accelerated into the target by the laser irradiation, the sheath expands away from the rear surface of the foil, developing a bell-shaped curvature. The protons are then accelerated normal to the sheath field, which is at the leading edge of the expansion. Due to the bell-shaped curvature, protons that are accelerated further away from the central axis of the laser interaction experience gradients within the expansion causing the protons to gain radial velocity, which changes the angle of divergence of the protons. The radial velocity gained by the protons affects the trajectory of the protons, resulting in a calculated real focal position when trajectories are calculated the ray-tracing technique. The trajectories of the protons are further affected by the mounting technique. When the foils are mounted to washers for stability, electrons accelerated in the foil escaped into the washer creating a field along the interior wall of washer. The field affects the proton trajectories near the wall and decreases the laser to proton conversion efficiency. With the understanding gained from the flat foil targets, proton focusing is further investigated using freestanding hemispherical shell targets. Using the 3D ray-tracing technique, the calculated focal position is determined to be located inside the radius of curvature of the hemisphere, which is less than the distance of 1.7R (where R is the radius of curvature of the hemispherical shell) determined from proton heating experiments. With the aid of particle-in-cell (PIC) simulations, using the code LSP (large-scale-plasma), it was determined that proton trajecto

Bartal, Teresa Jean

185

200 MeV proton radiography studies with a hand phantom using a prototype proton CT scanner.  

PubMed

Proton radiography has applications in patient alignment and verification procedures for proton beam radiation therapy. In this paper, we report an experiment which used 200 MeV protons to generate proton energy-loss and scattering radiographs of a hand phantom. The experiment used the first-generation proton computed tomography (CT) scanner prototype, which was installed on the research beam line of the clinical proton synchrotron at Loma Linda University Medical Center. It was found that while both radiographs displayed anatomical details of the hand phantom, the energy-loss radiograph had a noticeably higher resolution. Nonetheless, scattering radiography may yield more contrast between soft and bone tissue than energy-loss radiography, however, this requires further study. This study contributes to the optimization of the performance of the next-generation of clinical proton CT scanners. Furthermore, it demonstrates the potential of proton imaging (proton radiography and CT), which is now within reach of becoming available as a new, potentially low-dose medical imaging modality. PMID:24710156

Plautz, Tia; Bashkirov, V; Feng, V; Hurley, F; Johnson, R P; Leary, C; Macafee, S; Plumb, A; Rykalin, V; Sadrozinski, H F-W; Schubert, K; Schulte, R; Schultze, B; Steinberg, D; Witt, M; Zatserklyaniy, A

2014-04-01

186

200 MeV Proton Radiography Studies with a Hand Phantom Using a Prototype Proton CT Scanner  

PubMed Central

Proton radiography has applications in patient alignment and verification procedures for proton beam radiation therapy. In this paper, we report an experiment which used 200 MeV protons to generate proton energy-loss and scattering radiographs of a hand phantom. The experiment used the first-generation proton CT scanner prototype, which was installed on the research beam line of the clinical proton synchrotron at Loma Linda University Medical Center (LLUMC). It was found that while both radiographs displayed anatomical details of the hand phantom, the energy-loss radiograph had a noticeably higher resolution. Nonetheless, scattering radiography may yield more contrast between soft and bone tissue than energy-loss radiography, however, this requires further study. This study contributes to the optimization of the performance of the next-generation of clinical proton CT scanners. Furthermore, it demonstrates the potential of proton imaging (proton radiography and CT), which is now within reach of becoming available as a new, potentially low-dose medical imaging modality.

Plautz, Tia; Bashkirov, V.; Feng, V.; Hurley, F.; Johnson, R.P.; Leary, C.; Macafee, S.; Plumb, A.; Rykalin, V.; Sadrozinski, H.F.-W.; Schubert, K.; Schulte, R.; Schultze, B.; Steinberg, D.; Witt, M.; Zatserklyaniy, A.

2014-01-01

187

Electron-proton spectrometer  

NASA Technical Reports Server (NTRS)

An electron-proton spectrometer was designed to measure the geomagnetically trapped radiation in a geostationary orbit at 6.6 earth radii in the outer radiation belt. This instrument is to be flown on the Applications Technology Satellite-F (ATS-F). The electron-proton spectrometer consists of two permanent magnet surface barrier detector arrays and associated electronics capable of selecting and detecting electrons in three energy ranges: (1) 30-50 keV, (2) 150-200 keV, and (3) 500 keV and protons in three energy ranges. The electron-proton spectrometer has the capability of measuring the fluxes of electrons and protons in various directions with respect to the magnetic field lines running through the satellite. One magnet detector array system is implemented to scan between EME north and south through west, sampling the directional flux in 15 steps. The other magnet-detector array system is fixed looking toward EME east.

Winckler, J. R.

1973-01-01

188

Proton Engineering Frontier Project  

SciTech Connect

PEFP (Proton Engineering Frontier Project) approved and launched by the Korean government in July 2002 includes a 100MeV proton linear accelerator development and its utilization and application programs. In the first phase of the project from 2002 to 2005, a 20MeV proton linear accelerator is under development. It consists of 50keV proton injector, 3MeV RFQ, and 20MeV DTL. The 50keV injector had been installed and tested, the 3MeV RFQ is under beam test, and the 20MeV DTL is being fabricated and will be assembled for the beam test in 2005. In parallel, application and utilization programs using proton beam have been planned and developed. Some of them are being carried out. The status and progresses of the project are reported in detail.

Choi, Byung-Ho [Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2005-06-08

189

Proton Engineering Frontier Project  

NASA Astrophysics Data System (ADS)

PEFP (Proton Engineering Frontier Project) approved and launched by the Korean government in July 2002 includes a 100MeV proton linear accelerator development and its utilization and application programs. In the first phase of the project from 2002 to 2005, a 20MeV proton linear accelerator is under development. It consists of 50keV proton injector, 3MeV RFQ, and 20MeV DTL. The 50keV injector had been installed and tested, the 3MeV RFQ is under beam test, and the 20MeV DTL is being fabricated and will be assembled for the beam test in 2005. In parallel, application and utilization programs using proton beam have been planned and developed. Some of them are being carried out. The status and progresses of the project are reported in detail.

Choi, Byung-Ho

2005-06-01

190

Real-time prompt gamma monitoring in spot-scanning proton therapy using imaging through a knife-edge-shaped slit  

NASA Astrophysics Data System (ADS)

In this paper we report on Monte Carlo simulations to investigate real-time monitoring of the track depth profile in particle therapy by measuring prompt gamma ray emissions: a high sensitivity imaging system employing a knife-edge-shaped slit combined with a position-sensitive gamma detector was evaluated. Calculations to test this new concept were performed for a head-sized software phantom. Clear spatial correlation is shown between the distribution of gamma rays detected with energies above 1.5 MeV and the distribution of prompt gamma rays emitted from the phantom. The number of neutrons originating from nuclear reactions in the phantom that are detected at these high energies is small. Most importantly it is shown that under common therapy conditions enough data may be collected during one spot-step (of the order of 10 ms) to locate the distal dose edge with a 1? accuracy of better than 1 mm. This indicates that simple slit cameras have high potential for accurate real-time particle therapy adjustment and may become a practical way to improve particle therapy accuracy.

Bom, Victor; Joulaeizadeh, Leila; Beekman, Freek

2012-01-01

191

Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study  

SciTech Connect

Proton computed tomography (pCT) has been explored in the past decades because of its unique imaging characteristics, low radiation dose, and its possible use for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images is challenging because the proton path within the object to be imaged is statistically affected by multiple Coulomb scattering. In this paper, we employ GEANT4-based Monte Carlo simulations of the two-dimensional pCT reconstruction of an elliptical phantom to investigate the possible use of the algebraic reconstruction technique (ART) with three different path-estimation methods for pCT reconstruction. The first method assumes a straight-line path (SLP) connecting the proton entry and exit positions, the second method adapts the most-likely path (MLP) theoretically determined for a uniform medium, and the third method employs a cubic spline path (CSP). The ART reconstructions showed progressive improvement of spatial resolution when going from the SLP [2 line pairs (lp) cm{sup -1}] to the curved CSP and MLP path estimates (5 lp cm{sup -1}). The MLP-based ART algorithm had the fastest convergence and smallest residual error of all three estimates. This work demonstrates the advantage of tracking curved proton paths in conjunction with the ART algorithm and curved path estimates.

Li Tianfang; Liang Zhengrong; Singanallur, Jayalakshmi V.; Satogata, Todd J.; Williams, David C.; Schulte, Reinhard W. [Departments of Radiology, Computer Science, and Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York 11794 (United States); Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States); Santa Cruz Institute for Particle Physics, University of California at Santa Cruz, Santa Cruz, California 95064 (United States); Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States)

2006-03-15

192

Shapes of the Proton  

NASA Astrophysics Data System (ADS)

The aim of this talk is to interpret the recent exciting experimental results for proton and neutron electromagnetic form factors using Poincaré invariance and chiral symmetry. I discuss a relativistic interpretation for why the proton's ratio of charge to magnetic form factors, G_E/G_M, falls and why the ratio of Pauli to Dirac form factors QF_2/F1 is approximately constant is presented. Poincaré invariance is respected by expressing the quark wave functions of the proton in terms of Dirac spinors. Therefore the quarks carry non-zero orbital angular momentum, and the proton can be said to have a non-spherical shape. This statement is specified by defining spin-dependent quark densities as matrix elements of density operators in proton states of definite spin-polarization. Then the proton has an infinite variety of non-spherical shapes. For high momentum quarks with spin parallel to that of the proton, the shape resembles that of a peanut, but for quarks with anti-parallel spin the shape is that of a bagel. Reproducing the observed neutron G_E^n mandates the inclusion of the effects of the pion cloud. The full relativistic model with a pion cloud provides a reasonably good reproduction of all of the nucleon electromagnetic form factors.

Miller, Gerald A.

2003-05-01

193

The Proton launcher  

NASA Astrophysics Data System (ADS)

The capabilities, design features and missions for the Soviet Proton booster are described. The Proton, outfitted with six strap-on boosters, launched the Vega 1 and 2 Venus/Halley dual mission spacecraft. RD-253 engines burn N2O4 and UDMH fuels, possibly through a preburner before the combustion chamber. A vacuum thrust of 450,000 lb is projected for the engine. Analyses are presented to set the launch weight at 1,600,000 lb, implying that the vehicle is based on an ICBM design. It is suggested that the Proton has sufficiently high noise and vibration levels to prohibit it from being man-rated.

Bond, A.; Parfitt, J.

1985-08-01

194

MR imaging of osteochondral grafts and autologous chondrocyte implantation  

Microsoft Academic Search

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte\\u000a implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become\\u000a the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage\\u000a sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD\\/T2-FSE)

S. Trattnig; S. A. Millington; P. Szomolanyi; S. Marlovits

2007-01-01

195

Protonated salicylaldehyde: Electronic properties  

NASA Astrophysics Data System (ADS)

The excitation spectrum of protonated salicylaldehyde has been recorded in the 20,800-22,400 cm-1 region (480-450 nm). The first excited state of protonated salicylaldehyde is a ??? state, largely red shifted as compared to the ??? transition of its neutral analogue. Like protonated benzaldehyde and in contrast to some other protonated aromatic molecules such as benzene or tryptophan in which the excited state dynamics is so fast that no vibrational structure can be observed, the vibrational bands are well resolved and assigned. This molecule has many low energy isomers and the simulations of the electronic spectrum via ab initio excited state optimizations and Franck-Condon calculations are precise enough to assign the observed electronic spectrum to one of the isomers.

Alata, Ivan; Omidyan, Reza; Broquier, Michel; Dedonder, Claude; Jouvet, Christophe

2012-05-01

196

Electroluminescent Proton Transfer Polymers.  

National Technical Information Service (NTIS)

Effects of molecular size, extended conformation, and excimer formation on excited state intramolecular proton transfer (ESIPT) in main chain polymers were investigated in a series of homopolymers and copolymers. Several polymers were shown to exhibit bot...

S. A. Jenekhe X. Zhang R. M. Tarkka

1998-01-01

197

Baryogenesis and Proton Decay.  

National Technical Information Service (NTIS)

The constraints are analyzed that proton decay experiments and cosmologically sound unification models impose on each other. An intermediate scale of around 10 sup 10 GeV arises from considerations on baryogenesis, inflation and supersymmetry breaking. An...

M. Ruiz-Altaba

1986-01-01

198

Proton-proton bremsstrahlung at 310 MeV  

Microsoft Academic Search

Proton-proton bremsstrahlung measurements have been made at 310 MeV by the WASA-PROMICE collaboration [1] at the CELSIUS storage ring. Detailed measurements of proton-proton coincidences in the forward direction yielded kinematically complete data mainly for events with high-energy gammas in the CM system. Measurements of coincidences between a forward-going proton and a wide-angle photon yielded complementary information over a large range

Jozef Zlomanczuk; Arne Johansson

1998-01-01

199

Proton-Proton Physics with ALICE  

NASA Astrophysics Data System (ADS)

The main goal of ALICE (A Large Hadron Collider Experiment) is the study of heavy-ion collisions at the CERN Large Hadron Collider (LHC). In addition to heavy systems, the ALICE physics programme also includes data taking with proton beams. This is primarily aimed at providing reference data for nucleusnucleus collisions, but at the same time allows for a number of genuine pp physics studies. An overview of the ALICE pp results is presented in this paper.

Vercellin, Ermanno

2013-11-01

200

Dynamics of global scale electron and proton precipitation induced by a solar wind pressure pulse  

Microsoft Academic Search

On April 28 2001, simultaneous global images of electron and proton aurora were obtained by IMAGE-FUV following a sudden increase of solar wind dynamic pressure. The local time and intensity distribution of both types of precipitation are examined and compared. It is found that the electron and the proton precipitation both start in the post noon sector and expand concurrently,

M. Meurant; J.-C. Gérard; B. Hubert; V. Coumans; C. Blockx; N. Østgaard; S. B. Mende

2003-01-01

201

Proton beam therapy facility  

SciTech Connect

It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs.

Not Available

1984-10-09

202

Proton irradiation on materials  

NASA Technical Reports Server (NTRS)

A computer code is developed by utilizing a radiation transport code developed at NASA Langley Research Center to study the proton radiation effects on materials which have potential application in NASA's future space missions. The code covers the proton energy from 0.01 Mev to 100 Gev and is sufficient for energetic protons encountered in both low earth and geosynchronous orbits. With some modification, the code can be extended for particles heavier than proton as the radiation source. The code is capable of calculating the range, stopping power, exit energy, energy deposition coefficients, dose, and cumulative dose along the path of the proton in a target material. The target material can be any combination of the elements with atomic number ranging from 1 to 92, or any compound with known chemical composition. The generated cross section for a material is stored and is reused in future to save computer time. This information can be utilized to calculate the proton dose a material would receive in an orbit when the radiation environment is known. It can also be used to determine, in the laboratory, the parameters such as beam current of proton and irradiation time to attain the desired dosage for accelerated ground testing of any material. It is hoped that the present work be extended to include polymeric and composite materials which are prime candidates for use as coating, electronic components, and structure building. It is also desirable to determine, for ground testing these materials, the laboratory parameters in order to simulate the dose they would receive in space environments. A sample print-out for water subject to 1.5 Mev proton is included as a reference.

Chang, C. Ken

1993-01-01

203

Proton transport by halorhodopsin  

SciTech Connect

In halorhodopsin from Natronobacterium pharaonis, a light-driven chloride pump, the chloride binding site also binds azide. When azide is bound at this location the retinal Schiff base transiently deprotonates after photoexcitation with light >530 nm, like in the light-driven proton pump bacteriorhodopsin. As in the photocycle of bacteriorhodopsin, pyranine detects the release of protons to the bulk. The subsequent reprotonation of the Schiff base is also dependent on azide, but with different kinetics that suggest a shuttling of protons from the surface as described earlier for halorhodopsin from Halobacterium salinarium. The azide-dependent, bacteriorhodopsin-like photocycle results in active electrogenic proton transport in the cytoplasmic to extracellular direction, detected in cell envelope vesicle suspensions both with a potential-sensitive electrode and by measuring light-dependent pH change. We conclude that in halorhodopsin an azide bound to the extracellular side of the Schiff base, and another azide shuttling between the Schiff base and the cytoplasmic surface, fulfill the functions of Asp-85 and Asp-96, respectively, in bacteriorhodopsin. Thus, although halorhodopsin is normally a chloride ion pump, it evidently contains all structural requirements, except an internal proton acceptor and a donor, of a proton pump. This observation complements our earlier finding that when a chloride binding site was created in bacteriorhodopsin through replacement of Asp-85 with a threonine, that protein became a chloride ion pump. 52 refs., 9 figs.

Varo, G. [Hungarian Academy of Sciences, Szeged, HU (United States)] [Hungarian Academy of Sciences, Szeged, HU (United States); Brown, L.S.; Needleman, R. [and others] [and others

1996-05-28

204

IMAGE Spacecraft Pictures Aurora  

NSDL National Science Digital Library

This NASA site hosts a composite image of the southern lights Aurora over the South Pole. A link enables visitors to view a video of this aurora. The image of the Aurora is overlaid on a NASA âBlue Marbleâ image also captured by satellite. Text describes the distortion of Earthâs magnetic field by the stream of protons and electrons from the sun.

2012-12-24

205

Proton conductivity: Materials and applications  

Microsoft Academic Search

In this review, the phenomenon of proton conductivity in materials and the elements of proton conduction mechanisms-proton transfer, structural reorganization and diffusional motion of extended moieties-are discussed with special emphasis on proton chemistry. This is characterized by a strong proton localization within the valence electron density of electronegative species (e.g., oxygen, nitrogen) and self-localization effects due to solvent interactions which

Klaus-Dieter Kreuer

1996-01-01

206

Feasibility study of proton-based quality assurance of proton range compensator  

NASA Astrophysics Data System (ADS)

All patient specific range compensators (RCs) are customized for achieving distal dose conformity of target volume in passively scattered proton therapy. Compensators are milled precisely using a computerized machine. In proton therapy, precision of the compensator is critical and quality assurance (QA) is required to protect normal tissues and organs from radiation damage. This study aims to evaluate the precision of proton-based quality assurance of range compensator. First, the geometry information of two compensators was extracted from the DICOM Radiotherapy (RT) plan. Next, RCs were irradiated on the EBT film individually by proton beam which is modulated to have a photon-like percent depth dose (PDD). Step phantoms were also irradiated on the EBT film to generate calibration curve which indicates relationship between optical density of irradiated film and perpendicular depth of compensator. Comparisons were made using the mean absolute difference (MAD) between coordinate information from DICOM RT and converted depth information from the EBT film. MAD over the whole region was 1.7, and 2.0 mm. However, MAD over the relatively flat regions on each compensator selected for comparison was within 1 mm. These results shows that proton-based quality assurance of range compensator is feasible and it is expected to achieve MAD over the whole region less than 1 mm with further correction about scattering effect of proton imaging.

Park, S.; Jeong, C.; Min, B. J.; Kwak, J.; Lee, J.; Cho, S.; Shin, D.; Lim, Y. K.; Park, S. Y.; Lee, S. B.

2013-06-01

207

Proton Ratio of HL-2A Bucket Ion Source  

NASA Astrophysics Data System (ADS)

For heating the tokamak plasma effectively, the ion source must be capable of producing ions with high proton ratio. The proton ratio, which is found to be more than 65.6% at the ion current of 19.6 A with the extraction voltage of 39.6 kV, is measured with an image spectrograph by Doppler shift effect of Balmer-?-radiation spectrum emitted from fast hydrogen particles. The tendency of proton ratio with the ion density in experiment is almost the same as the mode devised by Zhang et al. Okumura et al. only gave the affection of the plasma volume and ion loss area on the proton ratio, but the relationship between the ion density in chamber and the proton ratio was not presented. We give the relationship.

Yu, Li-Ming; Lei, Guang-Jiu; Cao, Jian-Yong; Yang, Li-Mei; Jiang, Shao-Feng; Han, Xiao-Yu; Zhang, Xian-Ming; Sun, Ping; Zou, Gui-Qing; Lu, Da-Lun; Liu, He; Jiang, Tao; Duan, Xu-Ru

2010-04-01

208

Proton Radiography Peers into Metal Solidification  

NASA Astrophysics Data System (ADS)

Historically, metals are cut up and polished to see the structure and to infer how processing influences the evolution. We can now peer into a metal during processing without destroying it using proton radiography. Understanding the link between processing and structure is important because structure profoundly affects the properties of engineering materials. Synchrotron x-ray radiography has enabled real-time glimpses into metal solidification. However, x-ray energies favor the examination of small volumes and low density metals. Here we use high energy proton radiography for the first time to image a large metal volume (>10,000 mm3) during melting and solidification. We also show complementary x-ray results from a small volume (<1 mm3), bridging four orders of magnitude. Real-time imaging will enable efficient process development and the control of structure evolution to make materials with intended properties; it will also permit the development of experimentally informed, predictive structure and process models.

Clarke, Amy; Imhoff, Seth; Gibbs, Paul; Cooley, Jason; Morris, Christopher; Merrill, Frank; Hollander, Brian; Mariam, Fesseha; Ott, Thomas; Barker, Martha; Tucker, Tim; Lee, Wah-Keat; Fezzaa, Kamel; Deriy, Alex; Patterson, Brian; Clarke, Kester; Montalvo, Joel; Field, Robert; Thoma, Dan; Smith, James; Teter, David

2013-06-01

209

Proton Radiography Peers into Metal Solidification  

PubMed Central

Historically, metals are cut up and polished to see the structure and to infer how processing influences the evolution. We can now peer into a metal during processing without destroying it using proton radiography. Understanding the link between processing and structure is important because structure profoundly affects the properties of engineering materials. Synchrotron x-ray radiography has enabled real-time glimpses into metal solidification. However, x-ray energies favor the examination of small volumes and low density metals. Here we use high energy proton radiography for the first time to image a large metal volume (>10,000?mm3) during melting and solidification. We also show complementary x-ray results from a small volume (<1?mm3), bridging four orders of magnitude. Real-time imaging will enable efficient process development and the control of structure evolution to make materials with intended properties; it will also permit the development of experimentally informed, predictive structure and process models.

Clarke, Amy; Imhoff, Seth; Gibbs, Paul; Cooley, Jason; Morris, Christopher; Merrill, Frank; Hollander, Brian; Mariam, Fesseha; Ott, Thomas; Barker, Martha; Tucker, Tim; Lee, Wah-Keat; Fezzaa, Kamel; Deriy, Alex; Patterson, Brian; Clarke, Kester; Montalvo, Joel; Field, Robert; Thoma, Dan; Smith, James; Teter, David

2013-01-01

210

Sydenham's chorea: MRI and proton spectroscopy  

Microsoft Academic Search

We present the MRI and proton spectroscopy findings in a child with clinical diagnosis of Sydenham's chorea. MRI showed high\\u000a signal in the caudate nuclei and putamina on T2-weighted images. We believe that the spectra showed an abnormality in the\\u000a number and\\/or function of neurons, lipids from cellular breakdown (cytolytic effect of antibodies), aminoacids (related to\\u000a the presence of antibodies

M. Castillo; L. Kwock; A. Arbelaez

1999-01-01

211

Magnifying lens for 800 MeV proton radiography  

SciTech Connect

This article describes the design and performance of a magnifying magnetic-lens system designed, built, and commissioned at the Los Alamos National Laboratory (LANL) for 800 MeV flash proton radiography. The technique of flash proton radiography has been developed at LANL to study material properties under dynamic loading conditions through the analysis of time sequences of proton radiographs. The requirements of this growing experimental program have resulted in the need for improvements in spatial radiographic resolution. To meet these needs, a new magnetic lens system, consisting of four permanent magnet quadrupoles, has been developed. This new lens system was designed to reduce the second order chromatic aberrations, the dominant source of image blur in 800 MeV proton radiography, as well as magnifying the image to reduce the blur contribution from the detector and camera systems. The recently commissioned lens system performed as designed, providing nearly a factor of three improvement in radiographic resolution.

Merrill, F. E.; Campos, E.; Espinoza, C.; Hogan, G.; Hollander, B.; Lopez, J.; Mariam, F. G.; Morley, D.; Morris, C. L.; Murray, M.; Saunders, A.; Schwartz, C.; Thompson, T. N. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87544 (United States)

2011-10-15

212

High Temperature Protonic Conductors  

NASA Technical Reports Server (NTRS)

High Temperature Protonic Conductors (HTPC) with the perovskite structure are envisioned for electrochemical membrane applications such as H2 separation, H2 sensors and fuel cells. Successive membrane commercialization is dependent upon addressing issues with H2 permeation rate and environmental stability with CO2 and H2O. HTPC membranes are conventionally fabricated by solid-state sintering. Grain boundaries and the presence of intergranular second phases reduce the proton mobility by orders of magnitude than the bulk crystalline grain. To enhanced protonic mobility, alternative processing routes were evaluated. A laser melt modulation (LMM) process was utilized to fabricate bulk samples, while pulsed laser deposition (PLD) was utilized to fabricate thin film membranes . Sr3Ca(1+x)Nb(2-x)O9 and SrCe(1-x)Y(x)O3 bulk samples were fabricated by LMM. Thin film BaCe(0.85)Y(0.15)O3 membranes were fabricated by PLD on porous substrates. Electron microscopy with chemical mapping was done to characterize the resultant microstructures. High temperature protonic conduction was measured by impedance spectroscopy in wet air or H2 environments. The results demonstrate the advantage of thin film membranes to thick membranes but also reveal the negative impact of defects or nanoscale domains on protonic conductivity.

Dynys, Fred; Berger, Marie-Helen; Sayir, Ali

2007-01-01

213

Proton transfer in organic scaffolds  

NASA Astrophysics Data System (ADS)

This dissertation focuses on the fundamental understanding of the proton transfer process and translating the knowledge into design/development of new organic materials for efficient non-aqueous proton transport. For example, what controls the shuttling of a proton between two basic sites? a) Distance between two groups? or b) the basicity? c) What is the impact of protonation on molecular conformation when the basic sites are attached to rigid scaffolds? For this purpose, we developed several tunable proton sponges and studied proton transfer in these scaffolds theoretically as well as experimentally. Next we moved our attention to understand long-range proton conduction or proton transport. We introduced liquid crystalline (LC) proton conductor based on triphenylene molecule and established that activation energy barrier for proton transport is lower in the LC phase compared to the crystalline phase. Furthermore, we investigated the impact of several critical factors: the choice of the proton transferring groups, mobility of the charge carriers, intrinsic vs. extrinsic charge carrier concentrations and the molecular architectures on long-range proton transport. The outcome of this research will lead to a deeper understanding of non-aqueous proton transfer process and aid the design of next generation proton exchange membrane (PEM) for fuel cell.

Basak, Dipankar

214

A proton Computed Tomography system for medical applications  

NASA Astrophysics Data System (ADS)

Proton Computed Tomography (pCT) can improve the accuracy of both patient positioning and dose calculation in proton therapy, enabling to accurately reconstruct the electron density distribution of irradiated tissues. A pCT prototype, equipped with a silicon tracker and a YAG:Ce calorimeter, has been manufactured by an Italian collaboration. First tests under proton beam allowed obtaining good quality tomographic images of a non-homogeneous phantom. Manufacturing of a new large area system with real-time data acquisition is under way.

Sipala, V.; Bruzzi, M.; Bucciolini, M.; Carpinelli, M.; Cirrone, G. A. P.; Civinini, C.; Cuttone, G.; Lo Presti, D.; Pallotta, S.; Pugliatti, C.; Randazzo, N.; Romano, F.; Scaringella, M.; Stancampiano, C.; Talamonti, C.; Tesi, M.; Vanzi, E.; Zani, M.

2013-02-01

215

Predictions of diffractive cross sections in proton-proton collisions  

SciTech Connect

We review our pre-LHC predictions of the total, elastic, total-inelastic, and diffractive components of proton-proton cross sections at high energies, expressed in the form of unitarized expressions based on a special parton-model approach to diffraction employing inclusive proton parton distribution functions and QCD color factors and compare with recent LHC results.

Goulianos, Konstantin [Rockefeller University, 1230 York Avenue, New York, NY 10065 (United States)

2013-04-15

216

Electromagnetic proton\\/proton instabilities in the solar wind: Simulations  

Microsoft Academic Search

Proton velocity distributions in the high-speed solar wind are sometimes observed as two components of approximately equal temperature with an average relative drift velocity parallel to the background magnetic field. This relative drift gives rise to several proton\\/proton instabilities; for representative parameters, linear Vlasov theory demonstrates that the electromagnetic modes most likely to grow are a magnetosonic instability and an

William Daughton; S. Peter Gary; Dan Winske

1999-01-01

217

The Search for Proton Decay.  

ERIC Educational Resources Information Center

Provides the rationale for and examples of experiments designed to test the stability of protons and bound neutrons. Also considers the unification question, cosmological implications, current and future detectors, and current status of knowledge on proton decay. (JN)

Marshak, Marvin L.

1984-01-01

218

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

PubMed

We present a proof of principle study of proton radiography and proton computed tomography (pCT) based on time-resolved dose measurements. We used a prototype, two-dimensional, diode-array detector capable of fast dose rate measurements, to acquire proton radiographic images expressed directly in water equivalent path length (WEPL). The technique is based on the time dependence of the dose distribution delivered by a proton beam traversing a range modulator wheel in passive scattering proton therapy systems. The dose rate produced in the medium by such a system is periodic and has a unique pattern in time at each point along the beam path and thus encodes the WEPL. By measuring the time dose pattern at the point of interest, the WEPL to this point can be decoded. If one measures the time–dose patterns at points on a plane behind the patient for a beam with sufficient energy to penetrate the patient, the obtained 2D distribution of the WEPL forms an image. The technique requires only a 2D dosimeter array and it uses only the clinical beam for a fraction of second with negligible dose to patient. We first evaluated the accuracy of the technique in determining the WEPL for static phantoms aiming at beam range verification of the brain fields of medulloblastoma patients. Accurate beam ranges for these fields can significantly reduce the dose to the cranial skin of the patient and thus the risk of permanent alopecia. Second, we investigated the potential features of the technique for real-time imaging of a moving phantom. Real-time tumor tracking by proton radiography could provide more accurate validations of tumor motion models due to the more sensitive dependence of proton beam on tissue density compared to x-rays. Our radiographic technique is rapid (~100 ms) and simultaneous over the whole field, it can image mobile tumors without the problem of interplay effect inherently challenging for methods based on pencil beams. Third, we present the reconstructed pCT images of a cylindrical phantom containing inserts of different materials. As for all conventional pCT systems, the method illustrated in this work produces tomographic images that are potentially more accurate than x-ray CT in providing maps of proton relative stopping power (RSP) in the patient without the need for converting x-ray Hounsfield units to proton RSP. All phantom tests produced reasonable results, given the currently limited spatial and time resolution of the prototype detector. The dose required to produce one radiographic image, with the current settings, is ~0.7 cGy. Finally, we discuss a series of techniques to improve the resolution and accuracy of radiographic and tomographic images for the future development of a full-scale detector. PMID:24200989

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

2013-11-21

219

Proton Chemical Shifts  

NSDL National Science Digital Library

Created by Hans Reich, professor of organic chemistry at the Uiversity of Wisconsin-Madison, this site contains a compilation of proton chemical shifts and coupling constants. This is an excellent resource for providing students familiarity with Nuclear Magnetic Resonance (NMR) Spectroscopy Data.

Reich, Hans J.

2007-11-16

220

Proton Flare Project, 1966  

Microsoft Academic Search

The paper summarizes observations of solar and space phenomena related to the McMath region Number 8461 which passed over the solar disk during the 1966 Proton Flare Project period, from August 21 to September 4, and produced two important solar particle events on August 28 and September 2. The most important results are reviewed and interpretation of some of them

Z. Švestka; P. Simon

1969-01-01

221

Imaging atoms in medicine  

Microsoft Academic Search

The innovations in science and technology have allowed researchers to look inside the human body. In some cases, like MRI,\\u000a the protons present in the body generate enough signal for an image. However, the employ of certain atoms, metallic or non-metallic,\\u000a enable detection through different imaging techniques (computed tomography, nuclear imaging, ultrasound or optical imaging),\\u000a and improve the quality of

M. Teresa Albelda; Enrique García-España; Juan Carlos Frías

2009-01-01

222

Proton Spectrometer Belt Research (PSBR)  

Microsoft Academic Search

The National Reconnaissance Office (NRO), NASA, the Air Force Research Laboratory (AFRL), the Aerospace Corporation, the Los Alamos National Laboratory (LANL) and the Naval Research Laboratory (NRL) have jointly formed the Proton Spectrometer Belt Research (PSBR) program to meet two primary objectives: to measure the high-energy proton spectrum by placing the Relativistic Proton Spectrometer (RPS) instrument on board the Radiation

D. Dyers; J. Mazur; P. O'Brien; G. Ginet; G. Reeves

2008-01-01

223

Proton driver study at Fermilab.  

National Technical Information Service (NTIS)

Fermilab has started the design work of a high intensity proton source called the proton driver. It would provide a 4 MW proton beam to the target for muon production. This paper discusses the basic features of this machine and the associated accelerator ...

W. Chou

1999-01-01

224

Proton computed tomography from multiple physics processes  

NASA Astrophysics Data System (ADS)

Proton CT (pCT) nowadays aims at improving hadron therapy treatment planning by mapping the relative stopping power (RSP) of materials with respect to water. The RSP depends mainly on the electron density of the materials. The main information used is the energy of the protons. However, during a pCT acquisition, the spatial and angular deviation of each particle is recorded and the information about its transmission is implicitly available. The potential use of those observables in order to get information about the materials is being investigated. Monte Carlo simulations of protons sent into homogeneous materials were performed, and the influence of the chemical composition on the outputs was studied. A pCT acquisition of a head phantom scan was simulated. Brain lesions with the same electron density but different concentrations of oxygen were used to evaluate the different observables. Tomographic images from the different physics processes were reconstructed using a filtered back-projection algorithm. Preliminary results indicate that information is present in the reconstructed images of transmission and angular deviation that may help differentiate tissues. However, the statistical uncertainty on these observables generates further challenge in order to obtain an optimal reconstruction and extract the most pertinent information.

Bopp, C.; Colin, J.; Cussol, D.; Finck, Ch; Labalme, M.; Rousseau, M.; Brasse, D.

2013-10-01

225

Changes in water content and distribution in Quercus ilex leaves during progressive drought assessed by in vivo 1H magnetic resonance imaging  

PubMed Central

Background Drought is a common stressor in many regions of the world and current climatic global circulation models predict further increases in warming and drought in the coming decades in several of these regions, such as the Mediterranean basin. The changes in leaf water content, distribution and dynamics in plant tissues under different soil water availabilities are not well known. In order to fill this gap, in the present report we describe our study withholding the irrigation of the seedlings of Quercus ilex, the dominant tree species in the evergreen forests of many areas of the Mediterranean Basin. We have monitored the gradual changes in water content in the different leaf areas, in vivo and non-invasively, by 1H magnetic resonance imaging (MRI) using proton density weighted (?w) images and spin-spin relaxation time (T2) maps. Results ?w images showed that the distal leaf area lost water faster than the basal area and that after four weeks of similar losses, the water reduction was greater in leaf veins than in leaf parenchyma areas and also in distal than in basal leaf area. There was a similar tendency in all different areas and tissues, of increasing T2 values during the drought period. This indicates an increase in the dynamics of free water, suggesting a decrease of cell membranes permeability. Conclusions The results indicate a non homogeneous leaf response to stress with a differentiated capacity to mobilize water between its different parts and tissues. This study shows that the MRI technique can be a useful tool to follow non-intrusively the in vivo water content changes in the different parts of the leaves during drought stress. It opens up new possibilities to better characterize the associated physiological changes and provides important information about the different responses of the different leaf areas what should be taken into account when conducting physiological and metabolic drought stress studies in different parts of the leaves during drought stress.

2010-01-01

226

Validation of delayed gadolinium-enhanced magnetic resonance imaging of cartilage and T2 mapping for quantifying distal metacarpus/metatarsus cartilage thickness in Thoroughbred racehorses.  

PubMed

The purpose of this study was to determine whether delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping are accurate techniques for measuring cartilage thickness in the metacarpus3/metatarsus3 (Mc3/Mt3) of Thoroughbred racehorses. Twenty-four Mc3/Mt3 cadaver specimens were acquired from six healthy racehorses. Cartilage thickness was measured from postintra-articular Gd-DTPA(2-) images acquired using short tau inversion recovery (STIR), and proton density weighted (PDw) sequences, and compared with cartilage thickness measured from corresponding histologic images. Two observers performed each histologic measurement twice at three different sites, with measurement times spaced at least 5 days apart. Histologic cartilage thickness was measured at each of the three sites from the articular surface to the bone-cartilage interface, and from the articular surface to the mineralized cartilage interface (tidemark). Intra-observer repeatability was good to moderate for dGEMRIC where Mc3/Mt3 cartilage was not in contact with the proximal phalanx. Where the Mc3/Mt3 cartilage was in contact with the proximal phalanx cartilage, dGEMRIC STIR and T2 mapping PDw cartilage thicknesses of Mc3/Mt3 could not be measured reliably. When measured from the articular surface to the bone-cartilage interface, histologic cartilage thickness did not differ from STIR or PDw cartilage thickness at the site where the Mc3/Mt3 cartilage surface was separated from the proximal phalanx cartilage (P > 0.05). Findings indicated that dGEMRIC STIR and T2 mapping PDw are accurate techniques for measuring Mc3/Mt3 cartilage thickness at locations where the cartilage is not in direct contact with the proximal phalanx cartilage. PMID:23279707

Carstens, Ann; Kirberger, Robert M; Dahlberg, Leif E; Prozesky, Leon; Fletcher, Lizelle; Lammentausta, Eveliina

2013-01-01

227

PROTON THERAPY FOR PROSTATE CANCER  

PubMed Central

Proton therapy has been used in the treatment of prostate cancer for several decades, and interest surrounding its use continues to grow. Proton-based treatment techniques have evolved significantly over this time period, and several centers now routinely utilize technologies such as pencil beam scanning. However, whether the theoretical dosimetric advantages of the proton beam translate into clinically meaningful improvements for prostate cancer patients is unknown, and outcomes from single-arm experiences using whole courses of proton beam therapy in the treatment of early-stage prostate cancer have shown mixed results when compared to contemporary IMRT. A randomized trial comparing proton beam to IMRT in early-stage disease is open, and will be important in defining the role for proton therapy in this setting. We review the available evidence and present the current state of proton beam therapy for prostate cancer.

Mouw, Kent W; Trofimov, Alexei; Zietman, Anthony L; Efstathiou, Jason A

2013-01-01

228

The Eindhoven proton microbeam  

NASA Astrophysics Data System (ADS)

Proton microbeam equipment has been designed for element analysis with the PIXE method. To focus the proton beam of the EUT cyclotron (3.5 MeV) a quadruplet lens system with a magnification factor N = 0.025 and an acceptance of 1 mm mrad horizontally and 3 mm mrad vertically has been designed. The measured beam diameter is 40 × 60 ?m 2 with a beam current of 150 nA. Using diaphragms a spot of smaller diameter can be achieved at reduced currents. The beam is used for studying element topography by scanning samples. The samples are moved with an stepmotor controlled x- y slide. The target area studied can be chosen. A computer is used for on-line experiment control and data acquisition. All spectra from the target area are stored (256 kword) and analysed to obtain the X-ray energy topography of the scanned area. An example of such an investigation is presented.

Prins, M.; Hoffman, L. J. B.

1981-03-01

229

Light-driven proton or chloride pumping by halorhodopsin.  

PubMed Central

Halorhodopsin from Halobacterium halobium was purified and reconstituted with lipids from purple membranes. The resulting protein-containing membrane sheets were adsorbed to a planar lipid membrane and photoelectric properties were analyzed. Depending on light conditions, halorhodopsin acted either as a light-driven chloride pump or as a proton pump: green light caused chloride transport and additional blue light induced proton pumping. In the living cell, both to these vectorial processes would be directed toward the cytoplasm and, compared to ion transport by bacteriorhodopsin, this is an inversed proton flow. Azide, a catalyst for reversible deprotonation of halorhodopsin, enhanced proton transport, and the deprotonated Schiff base in the 13-cis configuration (H410) was identified as the key intermediate of this alternative catalytic cycle in halorhodopsin. While chloride transport in halorhodopsin is mediated by a one-photon process, proton transport requires the absorption of two photons: one photon for formation of H410 and release of a proton, and one photon for photoisomerization of H410 and re-formation of H578 with concomitant uptake of a proton by the Schiff base. Images

Bamberg, E; Tittor, J; Oesterhelt, D

1993-01-01

230

Smashing Protons to Smithereens  

ScienceCinema

Pleier discusses the extraordinary research taking place at the Large Hadron Collider (LHC) ? the world?s newest, biggest, and highest energy particle accelerator located at CERN. Pleier is one of hundreds of researchers from around the world working on ATLAS, a seven-story particle detector positioned at a point where the LHC?s oppositely circulating beams of protons slam into one another head-on.

Marc-André Pleier

2010-09-01

231

Smashing Protons to Smithereens  

SciTech Connect

Pleier discusses the extraordinary research taking place at the Large Hadron Collider (LHC) — the world’s newest, biggest, and highest energy particle accelerator located at CERN. Pleier is one of hundreds of researchers from around the world working on ATLAS, a seven-story particle detector positioned at a point where the LHC’s oppositely circulating beams of protons slam into one another head-on.

Marc-André Pleier

2010-05-05

232

Pion, Kaon, Proton and Antiproton Production in Proton-Proton Collisions  

NASA Technical Reports Server (NTRS)

Inclusive pion, kaon, proton, and antiproton production from proton-proton collisions is studied at a variety of proton energies. Various available parameterizations of Lorentz-invariant differential cross sections as a function of transverse momentum and rapidity are compared with experimental data. The Badhwar and Alper parameterizations are moderately satisfactory for charged pion production. The Badhwar parameterization provides the best fit for charged kaon production. For proton production, the Alper parameterization is best, and for antiproton production the Carey parameterization works best. However, no parameterization is able to fully account for all the data.

Norbury, John W.; Blattnig, Steve R.

2008-01-01

233

First measurements of laser-accelerated proton induced luminescence  

SciTech Connect

We present our first results about laser-accelerated proton induced luminescence in solids. In the first part, we describe the optimization of the proton source as a function of the target thickness as well as the laser pulse duration and energy. Due to the ultra high contrast ratio of our laser beam, we succeeded in using targets ranging from the micron scale down to nanometers thickness. The two optimal thicknesses we put in evidence are in good agreement with numerical simulations. Laser pulse duration shows a small influence on proton maximum energy, whereas the latter turns out to vary almost linearly as a function of laser energy. Thanks to this optimisation work, we have been able to acquire images of the proton energy deposition in a solid scintillator.

Floquet, V.; Ceccotti, T.; Dobosz Dufrenoy, S.; Bonnaud, G.; Monot, P.; Martin, Ph. [CEA, IRAMIS, SPAM, F-91191 Gif sur Yvette (France); Gremillet, L. [CEA, DAM, DIF, Bruyeres-le-Chatel, 91297 Arpajon (France)

2012-09-15

234

Differential Cross Sections for Proton-Proton Elastic Scattering  

NASA Technical Reports Server (NTRS)

Proton-proton elastic scattering is investigated within the framework of the one pion exchange model in an attempt to model nucleon-nucleon interactions spanning the large range of energies important to cosmic ray shielding. A quantum field theoretic calculation is used to compute both differential and total cross sections. A scalar theory is then presented and compared to the one pion exchange model. The theoretical cross sections are compared to proton-proton scattering data to determine the validity of the models.

Norman, Ryan B.; Dick, Frank; Norbury, John W.; Blattnig, Steve R.

2009-01-01

235

Association of Solar Wind Proton Flux Extremes with Pseudostreamers  

NASA Astrophysics Data System (ADS)

We investigate the characteristics and solar origins of a sub-population of the solar wind that possesses extreme values of proton flux. Ulysses observations including solar wind magnetic flux, proton flux, number density and velocity, and ionic composition are examined in this study. We find the departures of solar wind proton flux from its constancy occur for time intervals leading up to and encompassing the past two solar minima, and the extreme-proton-flux wind possesses the following characteristics: 1) it generally originates from sources middle-distant from the Heliospheric Current Sheet (HCS); 2) it is associated with a broad range of velocities and electron temperatures, but excludes very fast/cold wind; 3) it exhibits anticorrelation between electron temperature and proton velocity, as does the rest of the solar wind; 4) it has extreme proton density values relative to the rest of the solar wind; and 5) the extreme-high-proton-flux wind has radial component of open magnetic flux (Br) greater than the rest of the solar wind and both extreme-high and extreme-low wind do not possess the lowest values of Br flux. Comparing with SOHO EIT 195 A coronal images, we find the observed extreme-proton-flux wind has temporal and special coincidence with the appearance of low latitude coronal holes present in the recent two solar minima; and the magnetic field lines extrapolated by the Potential Field Source Surface (PFSS) model confirm there are coronal pseudostreamer structures involved. So we propose that these extreme-proton-flux wind can be associated with mid-to-low-latitude coronal holes and "pseudostreamer" structures.

Zhao, L.; Gibson, S. E.; Fisk, L. A.

2013-05-01

236

Statistics of the longitudinal splitting of proton aurora during substorms  

NASA Astrophysics Data System (ADS)

The lower-latitude boundary of the proton aurora, i.e., the isotropic boundary (IB), marks the transition from a full downgoing loss cone on the poleward side to an empty downgoing loss cone on the equatorward side. A number of authors have correlated this boundary with the amount of stretching in the magnetic field using GOES spacecraft. In this paper, we use 264 substorm events from the IMAGE SI-12 global proton auroral imager to show that during substorms, the proton aurora splits longitudinally 48% of the time. We hypothesize that the splitting is a result of the azimuthal growth of the substorm current wedge and show that splitting is more likely during stronger substorms (lower AL).

Gilson, M. L.; Raeder, J.; Donovan, E.; Ge, Y. S.; Mende, S. B.

2011-08-01

237

Proton structure functions at HERA  

NASA Astrophysics Data System (ADS)

The "proton structure" is a wide field. Discussed are predominantly the precision measurements of the proton structure functions at HERA and some of their implications for the LHC measurements. In addition, a discussion of what a proton structure function represents is provided. Finally, a connection to nuclear physics is attempted. This contribution is an updated reprint of a contribution to "Deep Inelastic Scattering 2012".1

Abt, Iris

2014-05-01

238

Proton MRS in neurological disorders.  

PubMed

Proton magnetic resonance spectroscopy (1H MRS) permits the acquisition of the signal arising from several brain metabolites. At long echo-time (TE) 1H MRS can detect N-acetyl-aspartate containing compounds, choline containing compounds, creatine + phosphocreatine and lactate. At short TE, lipids, tryglicerides, alanine, glutamate, glutamine, GABA, scyllo-inositol, glucose, myo-inositol, carnosine and histydine are visible. 1H MRS can be performed with single-voxel, multivoxel, single slice and multislice techniques. With single voxel 1H MRS it is possible to measure metabolites relaxation time, which allows the measurement of metabolite concentrations. This technique can be useful in the study of focal lesions in the central nervous system (CNS) such as epilepsy (pre-surgical identification of epileptic focus), brain tumors (evaluation of recurrence and radiation necrosis), stroke, multiple sclerosis, etc. Single slice and multislice 1H MRS imaging (1H MRSI) can be performed only at long TE and permits the mapping of the brain metabolites distribution which makes them particularly useful in studying diffuse diseases and heterogeneous lesions of the CNS. 1H MRS can also be useful in the evaluation of 'ischemic penumbra' of stroke; developmental (myelin and neuronal dysgenesis); head trauma (evaluation of cerebral damage not visible with MRI); degenerative disorders (identification of microscopic pathology not visible with MRI); and metabolic diseases (metabolic disturbances with specific metabolic patterns). PMID:10401593

Bonavita, S; Di Salle, F; Tedeschi, G

1999-05-01

239

Proton beam therapy  

PubMed Central

Conventional radiation therapy directs photons (X-rays) and electrons at tumours with the intent of eradicating the neoplastic tissue while preserving adjacent normal tissue. Radiation-induced damage to healthy tissue and second malignancies are always a concern, however, when administering radiation. Proton beam radiotherapy, one form of charged particle therapy, allows for excellent dose distributions, with the added benefit of no exit dose. These characteristics make this form of radiotherapy an excellent choice for the treatment of tumours located next to critical structures such as the spinal cord, eyes, and brain, as well as for paediatric malignancies.

Levin, W P; Kooy, H; Loeffler, J S; DeLaney, T F

2005-01-01

240

Feasibility of proton-activated implantable markers for proton range verification using PET  

NASA Astrophysics Data System (ADS)

Proton beam range verification using positron emission tomography (PET) currently relies on proton activation of tissue, the products of which decay with a short half-life and necessitate an on-site PET scanner. Tissue activation is, however, negligible near the distal dose fall-off region of the proton beam range due to their high interaction energy thresholds. Therefore Monte Carlo simulation is often supplemented for comparison with measurement; however, this also may be associated with systematic and statistical uncertainties. Therefore, we sought to test the feasibility of using long-lived proton-activated external materials that are inserted or infused into the target volume for more accurate proton beam range verification that could be performed at an off-site PET scanner. We irradiated samples of ?98% 18O-enriched water, natural Cu foils, and >97% 68Zn-enriched foils as candidate materials, along with samples of tissue-equivalent materials including 16O water, heptane (C7H16), and polycarbonate (C16H14O3)n, at four depths (ranging from 100% to 3% of center of modulation (COM) dose) along the distal fall-off of a modulated 160 MeV proton beam. Samples were irradiated either directly or after being embedded in Plastic Water® or balsa wood. We then measured the activity of the samples using PET imaging for 20 or 30 min after various delay times. Measured activities of candidate materials were up to 100 times greater than those of the tissue-equivalent materials at the four distal dose fall-off depths. The differences between candidate materials and tissue-equivalent materials became more apparent after longer delays between irradiation and PET imaging, due to the longer half-lives of the candidate materials. Furthermore, the activation of the candidate materials closely mimicked the distal dose fall-off with offsets of 1 to 2 mm. Also, signals from the foils were clearly visible compared to the background from the activated Plastic Water® and balsa wood phantoms. These results indicate that markers made from these candidate materials could be used for in vivo proton range verification using an off-site PET scanner.

Cho, Jongmin; Ibbott, Geoffrey; Gillin, Michael; Gonzalez-Lepera, Carlos; Titt, Uwe; Paganetti, Harald; Kerr, Matthew; Mawlawi, Osama

2013-11-01

241

Feasibility of proton-activated implantable markers for proton range verification using PET.  

PubMed

Proton beam range verification using positron emission tomography (PET) currently relies on proton activation of tissue, the products of which decay with a short half-life and necessitate an on-site PET scanner. Tissue activation is, however, negligible near the distal dose fall-off region of the proton beam range due to their high interaction energy thresholds. Therefore Monte Carlo simulation is often supplemented for comparison with measurement; however, this also may be associated with systematic and statistical uncertainties. Therefore, we sought to test the feasibility of using long-lived proton-activated external materials that are inserted or infused into the target volume for more accurate proton beam range verification that could be performed at an off-site PET scanner. We irradiated samples of ?98% (18)O-enriched water, natural Cu foils, and >97% (68)Zn-enriched foils as candidate materials, along with samples of tissue-equivalent materials including (16)O water, heptane (C7H16), and polycarbonate (C16H14O3)n, at four depths (ranging from 100% to 3% of center of modulation (COM) dose) along the distal fall-off of a modulated 160 MeV proton beam. Samples were irradiated either directly or after being embedded in Plastic Water® or balsa wood. We then measured the activity of the samples using PET imaging for 20 or 30 min after various delay times. Measured activities of candidate materials were up to 100 times greater than those of the tissue-equivalent materials at the four distal dose fall-off depths. The differences between candidate materials and tissue-equivalent materials became more apparent after longer delays between irradiation and PET imaging, due to the longer half-lives of the candidate materials. Furthermore, the activation of the candidate materials closely mimicked the distal dose fall-off with offsets of 1 to 2 mm. Also, signals from the foils were clearly visible compared to the background from the activated Plastic Water® and balsa wood phantoms. These results indicate that markers made from these candidate materials could be used for in vivo proton range verification using an off-site PET scanner. PMID:24099853

Cho, Jongmin; Ibbott, Geoffrey; Gillin, Michael; Gonzalez-Lepera, Carlos; Titt, Uwe; Paganetti, Harald; Kerr, Matthew; Mawlawi, Osama

2013-11-01

242

Shock-Induced Proton Aurora: Five Case Studies  

Microsoft Academic Search

The shock-induced proton aurora, observed in Doppler-shifted Lyman alpha with the IMAGE FUV Spectrographic Imager, is characterized by the same general features and behavior that have been reported in recent studies of the aurora that is produced primarily by precipitating electrons. Typical features include (1) a sudden, short-lived dayside brightening, covering over several hours of local time and often extending

W. S. Lewis; J. L. Burch; S. B. Mende; H. U. Frey; T. J. Immel

2003-01-01

243

Proton Upset Monte Carlo Simulation  

NASA Technical Reports Server (NTRS)

The Proton Upset Monte Carlo Simulation (PROPSET) program calculates the frequency of on-orbit upsets in computer chips (for given orbits such as Low Earth Orbit, Lunar Orbit, and the like) from proton bombardment based on the results of heavy ion testing alone. The software simulates the bombardment of modern microelectronic components (computer chips) with high-energy (.200 MeV) protons. The nuclear interaction of the proton with the silicon of the chip is modeled and nuclear fragments from this interaction are tracked using Monte Carlo techniques to produce statistically accurate predictions.

O'Neill, Patrick M.; Kouba, Coy K.; Foster, Charles C.

2009-01-01

244

MRI Plaque Imaging Detects Carotid Plaques with a High Risk for Future Cerebrovascular Events in Asymptomatic Patients  

PubMed Central

Purpose The aim of this study was to investigate prospectively whether MRI plaque imaging can identify patients with asymptomatic carotid artery stenosis who have an increased risk for future cerebral events. MRI plaque imaging allows categorization of carotid stenosis into different lesion types (I–VIII). Within these lesion types, lesion types IV–V and VI are regarded as rupture-prone plaques, whereas the other lesion types represent stable ones. Methods Eighty-three consecutive patients (45 male (54.2%); age 54–88 years (mean 73.2 years)) presenting with an asymptomatic carotid stenosis of 50–99% according to ECST-criteria were recruited. Patients were imaged with a 1.5-T scanner. T1-, T2-, time-of-flight-, and proton-density weighted studies were performed. The carotid plaques were classified as lesion type I–VIII. Clinical endpoints were ischemic stroke, TIA or amaurosis fugax. Survival analysis and log rank test were used to ascertain statistical significance. Results Six out of 83 patients (7.2%) were excluded: 4 patients had insufficient MR image quality; 1 patient was lost-to-follow-up; 1 patient died shortly after the baseline MRI plaque imaging. The following results were obtained by analyzing the remaining 77 patients. The mean time of follow-up was 41.1 months. During follow-up, n?=?9 (11.7%) ipsilateral ischemic cerebrovascular events occurred. Only patients presenting with the high-risk lesion types IV–V and VI developed an ipsilateral cerebrovascular event versus none of the patients presenting with the stable lesion types III, VII, and VIII (n?=?9 (11.7%) vs. n?=?0 (0%) during follow-up). Event-free survival was higher among patients with the MRI-defined stable lesion types (III, VII, and VIII) than in patients with the high-risk lesion types (IV–V and VI) (log rank test P<0.0001). Conclusions MRI plaque imaging has the potential to identify patients with asymptomatic carotid stenosis who are particularly at risk of developing future cerebral ischemia. MRI could improve selection criteria for invasive therapy in the future.

Esposito-Bauer, Lorena; Saam, Tobias; Ghodrati, Iman; Pelisek, Jaroslav; Heider, Peter; Bauer, Matthias; Wolf, Petra; Bockelbrink, Angelina; Feurer, Regina; Sepp, Dominik; Winkler, Claudia; Zepper, Peter; Boeckh-Behrens, Tobias; Riemenschneider, Matthias; Hemmer, Bernhard; Poppert, Holger

2013-01-01

245

Umbrella sampling of proton transfer in a creatine–water system  

NASA Astrophysics Data System (ADS)

Proton transfer reactions are among the most common processes in chemistry and biology. Proton transfer between creatine and surrounding solvent water is underlying the chemical exchange saturation transfer used as a contrast in magnetic resonance imaging. The free energy barrier, determined by first-principles umbrella sampling simulations (EaDFT 3 kcal/mol) is in the same order of magnitude as the experimentally obtained activation energy. The underlying mechanism is a first proton transfer from the guanidinium group to the water pool, followed by a second transition where a proton is "transferred back" from the nearest water molecule to the deprotonated nitrogen atom of creatine.

Ivchenko, Olga; Bachert, Peter; Imhof, Petra

2014-04-01

246

Spin matrix elements for the elastic proton-proton and proton-antiproton collisions  

Microsoft Academic Search

Motivated by the present extensive RHIC (BNL) spin program and further PAX project at FAIR, we study the possibility of explicit reconstruction of full set of helicity amplitudes by joint consideration of elastic proton-proton and proton-antiproton scattering. Procedure is based on the derivative relations for the helicity amplitudes, explicit parametrization of the leading spin non-flip amplitudes and crossing - symmetry

V. A. Okorokov; S. B. Nurushev

2007-01-01

247

Proton treatment room concepts for precision and efficiency.  

PubMed

Proton radiation therapy involves accurate delivery of proton beams to targets inside the body without direct visual control of the internal anatomy. Targeting of the tumor and avoidance of critical structures within the patient have to be both accurate and precise to achieve the desired therapeutic results. Good understanding of proton radiation delivery and patient alignment concepts in the treatment room is essential to achieve this goal. This overview article presents treatment room concepts that will ensure precise proton beam delivery and, at the same time, guarantee an efficient patient throughput. Concepts discussed include effective patient immobilization, image-guided alignment verification, appropriate training of radiotherapists, and the physician's integrative role in understanding the complex spatial relationships between tumor, organs at risk, treatment beam configuration, and application of proton radiation dose. It will be demonstrated that in addition to the technical armamentarium, now commonplace in modern radiation oncology departments, the interaction between radiation oncologist, medical physicist and radiotherapist is important for efficient operation of a proton treatment facility. PMID:17668953

Schulte, Reinhard W

2007-08-01

248

Proton cyclotron echoes at the ƒQ3 resonance  

NASA Astrophysics Data System (ADS)

We report here new observations on topside sounder ionograms from the Canadian ISIS II satellite of proton cyclotron echoes associated with the ƒQ3 resonance. Proton cyclotron echoes were first observed on swept frequency ionograms from the Canadian Alouette II satellite. The echoes occur on the ionograms at nearly constant apparent ranges which correspond to the proton cyclotron period at the satellite. The echoes were first found to be associated with the fundamental resonance of the electron cyclotron frequency, ƒH, and later reported at the 3ƒH and 4ƒH resonances. The new observations were made on ionograms when the satellite was located in regions with low dip angles less than 8°. This paper will present and discuss the features of these new proton cyclotron echoes, such as the presence often of two echo images, and possible generation mechanisms. A comparison with various ray-tracing calculations by Muldrew (1972a, b) suggests that these proton cyclotron echoes may occur when the particular waves responsible for the ƒQ3, 3ƒH and 4ƒH resonances interact with protons energized by the satellite antenna.

Horita, R. E.; Chen, G. M.

1995-09-01

249

Studies of electron and proton isochoric heating for fast ignition  

SciTech Connect

Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu K{alpha} fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced K{alpha}. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed.

Mackinnon, A; Key, M; Akli, K; Beg, F; Clarke, R; Clarke, D; Chen, M; Chung, H; Chen, S; Freeman, R; Green, J; Gu, P; Gregori, G; Highbarger, K; Habara, H; Hatchett, S; Hey, D; Heathcote, R; Hill, J; King, J; Kodama, R; Koch, J; Lancaster, K; Langdon, B; Murphy, C; Norreys, P; Neely, D; Nakatsutsumi, M; Nakamura, H; Patel, N; Patel, P; Pasley, J; Snavley, R; Stephens, R; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Tanaka, K; Tempo, M; Toley, M; Town, R; Wilks, S; VanWoerkom, L; Weber, R; Yabuuchi, T; Zhang, B

2006-10-02

250

Optical diagnostics of mercury jet for an intense proton target  

NASA Astrophysics Data System (ADS)

An optical diagnostic system is designed and constructed for imaging a free mercury jet interacting with a high intensity proton beam in a pulsed high-field solenoid magnet. The optical imaging system employs a backilluminated, laser shadow photography technique. Object illumination and image capture are transmitted through radiation-hard multimode optical fibers and flexible coherent imaging fibers. A retroreflected illumination design allows the entire passive imaging system to fit inside the bore of the solenoid magnet. A sequence of synchronized short laser light pulses are used to freeze the transient events, and the images are recorded by several high speed charge coupled devices. Quantitative and qualitative data analysis using image processing based on probability approach is described. The characteristics of free mercury jet as a high power target for beam-jet interaction at various levels of the magnetic induction field is reported in this paper.

Park, H.; Tsang, T.; Kirk, H. G.; Ladeinde, F.; Graves, V. B.; Spampinato, P. T.; Carroll, A. J.; Titus, P. H.; McDonald, K. T.

2008-04-01

251

Optical diagnostics of mercury jet for an intense proton target  

SciTech Connect

An optical diagnostic system is designed and constructed for imaging a free mercury jet interacting with a high intensity proton beam in a pulsed high-field solenoid magnet. The optical imaging system employs a backilluminated, laser shadow photography technique. Object illumination and image capture are transmitted through radiation-hard multimode optical fibers and flexible coherent imaging fibers. A retroreflected illumination design allows the entire passive imaging system to fit inside the bore of the solenoid magnet. A sequence of synchronized short laser light pulses are used to freeze the transient events, and the images are recorded by several high speed charge coupled devices. Quantitative and qualitative data analysis using image processing based on probability approach is described. The characteristics of free mercury jet as a high power target for beam-jet interaction at various levels of the magnetic induction field is reported in this paper.

Park, H.; Ladeinde, F. [SUNY at Stony Brook, New York 11794 (United States); Tsang, T.; Kirk, H. G. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Graves, V. B.; Spampinato, P. T.; Carroll, A. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Titus, P. H. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); McDonald, K. T. [Princeton University, Princeton, New Jersey 08544 (United States)

2008-04-15

252

Solar Proton Fluxes Since 1956.  

National Technical Information Service (NTIS)

The fluxes of protons emitted during solar flares since 1956 were evaluated. The depth-versus-activity profiles of exp 56 Co in several lunar rocks are consistent with the solar-proton fluxes detected by experiments on several satellites. Only about 20% o...

R. C. Reedy

1977-01-01

253

Proton Collimators for Fusion Reactors  

NASA Technical Reports Server (NTRS)

Proton collimators have been proposed for incorporation into inertial-electrostatic-confinement (IEC) fusion reactors. Such reactors have been envisioned as thrusters and sources of electric power for spacecraft and as sources of energetic protons in commercial ion-beam applications.

Miley, George H.; Momota, Hiromu

2003-01-01

254

Proton Spectrometer Belt Research (PSBR)  

NASA Astrophysics Data System (ADS)

The Proton Spectrometer Belt Research (PSBR) program will place Relativistic Proton Spectrometer (RPS) instrumentation on board the Radiation Belt Storm Probes spacecraft and is to measure the inner Van Allen belt protons with energies from 50 MeV to 2 GeV. Presently, the intensity of trapped protons with energies beyond about 150 MeV is not well known and thought to be underestimated in existing specification models. Such protons are known to pose a number of hazards to astronauts and spacecraft; including total ionizing dose, displacement damage, single event effects, and nuclear activation. This instrument will address a priority highly ranked by the scientific and technical community and will extend the measurement capability of this mission to a range beyond that originally planned.

Groves, C.; Selesnick, R. S.; Mazur, J. E.; Blake, J. B.; Clemmons, J. H.; O'Brien, T. P.; Friesen, L. M.; Katz, N.; Kolasinski, W. A.; Looper, M. D.

2006-12-01

255

An 800-MeV proton radiography facility for dynamic experiments  

SciTech Connect

The capability has been successfully developed at the Los Alamos Nuclear Science Center (LANSCE) to utilize a spatially and temporally prepared 800-MeV proton beam to produce proton radiographs. A series of proton bursts are transmitted through a dynamically varying object and transported, via a unique magnetic lens system, to an image plane. The magnetic lens system permits correcting for the effects of multiple coulomb scattering which would otherwise completely blur the spatially transmitted information at the image plane. The proton radiographs are recorded on either a time integrating film plate or with a recently developed multi-frame electronic imaging camera system. The latter technique permits obtaining a time dependent series of proton radiographs with time intervals (modulo 358 ns) up to many microseconds and variable time intervals between images. One electronically shuttered, intensified, CCD camera is required per image. These cameras can detect single protons interacting with a scintillating fiber optic array in the image plane but also have a dynamic range which permits recording radiographs with better than 5% statistics for observation of detailed density variations in the object. A number of tests have been carried out to characterize the quality of the proton radiography system for absolute mass determination, resolution, and dynamic range. Initial dynamic experiments characterized the temporal and spatial behavior of shock propagation in high explosives with up to six images per experiment. Based on experience with the prototype system, a number of upgrades are being implemented including the anticipated capability for enhanced mass discrimination through differential multiple coulomb scattering radiographs and more images with improved imaging techniques.

King, N.S.P.; Adams, K. [Los Alamos National Lab., NM (United States); Ables, E. [Lawrence Livermore National Lab., CA (United States)] [and others

1998-12-01

256

Magnetization Transfer or Spin-Lock? An Investigation of Off-Resonance Saturation Pulse Imaging with Varying Frequency Offsets  

Microsoft Academic Search

PURPOSE: To characterize near-resonance saturation pulse MR imaging on a 1.5-T scanner in order to gain insight into underlying mechanisms that alter tissue contrast and to optimize the technique for neuroimaging. METHODS: Off-resonance saturation pulses were applied to T1- weighted, spin-density-weighted, and T2-weighted sequences at frequency offsets ranging from 50 Hz to 20 000 Hz down field from water resonance.

John L. Ulmer; Vincent P. Mathews; Craig A. Hamilton; Allen D. Elster; Paul R. Moran

257

First observation of two-proton radioactivity in 48Ni  

SciTech Connect

The decay of the extremely neutron deficient 48Ni was studied by means of an imaging time projection chamber which allowed the recording of tracks of charged particles. Decays of 6 atoms were observed. Four of them clearly correspond to two-proton radioactivity providing the first direct evidence for this decay mode in 48Ni. Two decays represent -delayed proton emission. The half-life of 48Ni is determined to be T1=2 = 2:1+1:4 0:4 ms.

Pomorski, M. [University of Warsaw; Pfutzner, M. [University of Warsaw; Dominik, W. [University of Warsaw; Grzywacz, Robert Kazimierz [ORNL; Baumann, T. [Michigan State University, East Lansing; Berryman, J. S. [Michigan State University, East Lansing; Czyrkowski, H. [University of Warsaw; Dabrowski, Ryszard [Warsaw University; Ginter, T. N. [Michigan State University, East Lansing; Johnson, James W [ORNL; Kaminski, A. [PAN, Krakow, Poland; Kuzniak, A. [University of Tennessee, Knoxville (UTK); Larson, N. [Michigan State University, East Lansing; Liddick, S. N. [Michigan State University, East Lansing; Madurga, M [University of Tennessee, Knoxville (UTK); Mazzocchi, C. [University of Warsaw; Miernik, K. [Oak Ridge National Laboratory (ORNL); Miller, D [University of Tennessee, Knoxville (UTK); Paulauskas, S. [University of Tennessee, Knoxville (UTK); Pereira, J. [National Superconducting Cyclotron Laboratory (NSCL); Rykaczewski, Krzysztof Piotr [ORNL; Stolz, A. [Michigan State University, East Lansing; Suchyta, S. [Michigan State University, East Lansing

2011-01-01

258

Proton transfer reactions and dynamics in protonated water clusters.  

PubMed

Proton transfer reactions and dynamics were theoretically studied using the hydrogen-bond (H-bond) complexes formed from H(3)O(+) and nH(2)O, n = 1-4, as model systems. The investigations began with searching for characteristics of transferring protons in the gas phase and continuum aqueous solution using DFT method at the B3LYP/TZVP level, followed by Born-Oppenheimer molecular dynamics (BOMD) simulations at 350 K. B3LYP/TZVP calculations revealed the threshold asymmetric O-H stretching frequencies (?(OH)*) for the proton transfers in the Zundel complex (H(5)O) in the gas phase and continuum aqueous solution at 1984 and 1881 cm(-1), respectively. BOMD simulations suggested lower threshold frequencies (?(OH,MD)* = 1917 and 1736 cm(-1), respectively), with two characteristic ?(OH,MD) being the IR spectral signatures of the transferring protons. The low-frequency band could be associated with the "oscillatory shuttling motion" and the high-frequency band with the "structural diffusion motion". These can be regarded as the spectroscopic evidences of the formations of the shared-proton structure (O···H(+)···O) and the H(3)O(+)-H(2)O contact structure (O-H(+)···O), respectively. Since the quasi-dynamic equilibrium between the Zundel and Eigen complexes was suggested to be the rate-determining step, in order to achieve an "ideal" maximum efficiency of proton transfer, a concerted reaction pathway should be taken. The most effective interconversion between the two proton states, the shared-proton structure and the H(3)O(+)-H(2)O contact structure, can be reflected from comparable intensities of the oscillatory shuttling and structural diffusion bands. The present results iterated the previous conclusions that static proton transfer potentials cannot provide complete description of the structural diffusion process and it is essential to incorporate thermal energy fluctuations and dynamics in the model calculations. PMID:21283848

Lao-Ngam, Charoensak; Asawakun, Prapasri; Wannarat, Sornthep; Sagarik, Kritsana

2011-03-14

259

Proton transfer and proton concentrations in protonated Nafion fuel cell membranes.  

PubMed

Proton transfer in protonated Nafion fuel cell membranes is studied using several pyrene derivative photoacids. Proton transfer in the center of the Nafion nanoscopic water channels is probed with the highly charged photoacid 8-hydroxypyrene-1,3,6-trisulfonate (HPTS). At high hydration levels, both the time-integrated fluorescence spectrum and the fluorescence kinetics of HPTS permit the determination of hydronium concentration of the interior of the water pools in Nafion. The proton transfer kinetics of HPTS in protonated Nafion at maximum hydration are identical to the kinetics displayed by HPTS in a 0.5 M HCl solution. The hydronium concentration near the water interface in Nafion is estimated with rhodamine-6G to be 1.4 M. Excited state proton transfer (ESPT) is followed in the nonpolar side chain regions of Nafion with the photoacid 8-hydroxy-N,N,N',N',N'',N''-hexamethylpyrene-1,3,6-trisulfonamide (HPTA). Excited state proton transfer of HPTA is possible in protonated Nafion only at the highest hydration level due to a relatively high local pH. PMID:19572659

Spry, D B; Fayer, M D

2009-07-30

260

Nuclear Emulsion Film Detectors for Proton Radiography:. Design and Test of the First Prototype  

NASA Astrophysics Data System (ADS)

Proton therapy is nowadays becoming a wide spread clinical practice in cancer therapy and sophisticated treatment planning systems are routinely used to exploit at best the ballistic properties of charged particles. The information on the quality of the beams and the range of the protons is a key issue for the optimization of the treatment. For this purpose, proton radiography can be used in proton therapy to obtain direct information on the range of the protons, on the average density of the tissues for treatment planning optimization and to perform imaging with negligible dose to the patient. We propose an innovative method based on nuclear emulsion film detectors for proton radiography, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. Nuclear emulsion films interleaved with tissue equivalent absorbers can be fruitfully used to reconstruct proton tracks with very high precision. The first prototype of a nuclear emulsion based detector has been conceived, constructed and tested with a therapeutic proton beam at PSI. The scanning of the emulsions has been performed at LHEP in Bern, where a fully automated microscopic scanning technology has been developed for the OPERA experiment on neutrino oscillations. After track reconstruction, the first promising experimental results have been obtained by imaging a simple phantom made of PMMA with a step of 1 cm. A second phantom with five 5 × 5 mm2 section aluminum rods located at different distances and embedded in a PMMA structure has been also imaged. Further investigations are in progress to improve the resolution and to image more sophisticated phantoms.

Braccini, S.; Ereditato, A.; Kreslo, I.; Moser, U.; Pistillo, C.; Studer, S.; Scampoli, P.

2010-04-01

261

Jet energy measurement with the ATLAS detector in proton-proton collisions at ?{s}=7 TeV  

NASA Astrophysics Data System (ADS)

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of sqrt{s}=7 TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti- k t algorithm with distance parameters R=0.4 or R=0.6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta p T?20 GeV and pseudorapidities | ?|<4.5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2.5 % in the central calorimeter region (| ?|<0.8) for jets with 60? p T<800 GeV, and is maximally 14 % for p T<30 GeV in the most forward region 3.2?| ?|<4.5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon p T, the sum of the transverse momenta of tracks associated to the jet, or a system of low- p T jets recoiling against a high- p T jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high- p T jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined.

Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Aktas, A.; Alam, M. S.; Alam, M. A.; Albert, J.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asner, D.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Aubert, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avolio, G.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, D.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Battistoni, G.; Bauer, F.; Bawa, H. S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Beck, G. A.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Behar Harpaz, S.; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ben Ami, S.; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blazek, T.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bona, M.; Bondarenko, V. G.; Bondioli, M.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brown, H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.

2013-03-01

262

Proton diffusion along biological membranes.  

PubMed

Biological surfaces are known to be capable of retaining protons and facilitating their lateral diffusion. Since the surface dynamically exchanges protons with the bulk, the proton movement from a source to a target at the surface acquires a complicated pattern of coupled surface and bulk (2D + 3D) diffusion of which the main feature is that the surface acts as a proton-collecting antenna enhancing the proton flux from the bulk. A phenomenological model of this process is reviewed and its applications to recent experiments on lipid bilayers and small unilaminar vesicles are discussed. The model (i) introduces the important notions of the fast and slow regimes of proton exchange between the surface and the bulk, (ii) permits evaluation of the antenna radius and amplification coefficient in both regimes, (iii) explains the observed macroscopically large distances (in the micrometer range; Antonenko and Pohl 1998 FEBS Lett. 429 197) that the proton can travel along lipid membranes embedded into pure aqueous solutions, and (iv) predicts the dependence of the steady-state proton flux and the kinetics of the non-stationary diffusion upon the buffer concentration in buffered solutions. The surface diffusion coefficient for small unilaminar vesicles is calculated from experimental data (Sandén et al 2010 Proc. Natl Acad. Sci. USA 107 4129) to be 1 × 10(-5) cm(2) s(-1). The dependence of the shape of the kinetic curves representing protonation/deprotonation of a lipid-bound pH-sensitive dye attached to a planar bilayer lipid membrane upon the buffer concentration (Serowy et al 2003 Biophys. J. 84 1031) and the effect of changing the membrane composition (Antonenko and Pohl 2008 Eur. Biophys. J. 37 865) are explained. PMID:21613715

Medvedev, E S; Stuchebrukhov, A A

2011-06-15

263

Very high energy proton-proton cross section  

SciTech Connect

The recent Pierre Auger Observatory result suggesting a coincidence of extensive air showers arrival directions with 'nearby' active galactic nuclei and HiRes discovery of the Greisen-Zatsepin-Kuzmin cutoff indicates protons to be only or at least the strongly dominant component of primary extra galactic cosmic ray flux. However, showers initiated by these ultrahigh energy particles developed faster than predicted by the simulation calculations with conventional interaction models. This could be evidence of the substantial increase of the p-air cross section. The progress in understanding the proton-proton cross section description allows us to examine this possibility, and eventually reject it as an explanation of the ultrahigh energy cosmic ray 'pure proton' controversy.

Wibig, Tadeusz [University of Lodz, Department of Physics (Poland)and Andrzej Soltan Institute for Nuclear Studies, Uniwersytecka 5, 90-950 Lodz (Poland)

2009-05-01

264

RHIC Polarized proton operation  

SciTech Connect

The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above injection, the polarized hydrogen jet target runs for every fill with both beams. Based on the known analyzing power, there is very little polarization loss between injection and 100 GeV. An alternative way is to measure the asymmetry at 100 GeV followed by ramping up to 250 GeV and back down to 100 GeV and then to measure the asymmetry again at 100 GeV. If the asymmetry after the down ramp is similar to the measurement before the up ramp, polarization was also preserved during the ramp to 250 GeV. The analyzing power at storage energy can then be extracted from the asymmetries measured at 100 GeV and 250 GeV. The tune and orbit feedbacks are essential for the down ramp to be possible. The polarized proton operation is still going on. We will push bunch intensity higher until reaching the beam-beam limit. The even higher intensity will have to wait for the electron lenses to compensate the beam-beam effect. To understand the details of spin dynamics in RHIC with two snakes, spin simulation with the real magnet fields have been developed recently. The study will provide guidance for possible polarization loss schemes. Further polarization gain will requires a polarized source upgrade; more careful setup jump quads in the AGS to get full benefit; and control emittance in the whole accelerator chain.

Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D'Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

2011-03-28

265

Proton polarization at room temperature  

SciTech Connect

We have polarized protons in naphthalene doped with pentacene at higher temperature ({ge}77 K) and lower magnetic field ({approximately}3 kG) than those for ordinary polarized proton targets. Pentacene molecules have been excited with a laser beam. Protons in naphthalene have been polarized dynamically on the intermediate state of pentacene. We obtain about 13{percent} polarization at liquid nitrogen temperature in about 3kG with a N{sub 2}-laser of about 150 mW. It has been found to be also possible to obtain high polarization at room temperature. {copyright} {ital 1995 American Institute of Physics.}

Daigo, M. [Premedical Course, Wakayama Medical College, Wakayama 649-63 (Japan); Hirota, N. [Department of Chemistry, Kyoto University, Kyoto 606 (Japan); Iinuma, M.; Masaike, A.; Shake, I. [Department of Physics, Kyoto University, Kyoto 606 (Japan); Shimizu, H.M. [National Laboratory for High Energy Physics (KEK), Ibaraki-ken 305 (Japan); Takahashi, Y.; Takizawa, R. [Department of Physics, Kyoto University, Kyoto 606 (Japan); Terazima, M. [Department of Chemistry, Kyoto University, Kyoto 606 (Japan); Yabuzaki, T. [Department of Physics, Kyoto University, Kyoto 606 (Japan)

1995-09-01

266

Acceleration of polarized proton beams  

SciTech Connect

The acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. Full Siberian snakes are being developed for RHIC to make the acceleration of polarized protons to 250 GeV possible. A similar scheme is being studied for the 800 GeV HERA proton accelerator.

Roser, T.

1998-12-31

267

Near-threshold ? meson production in proton–proton collisions  

Microsoft Academic Search

The production of ? mesons has been measured in the proton-proton interaction close to the reaction threshold using the COSY-11 internal facility at the cooler synchrotron COSY. Total cross sections were determined for eight different excess energies (?) in the range from ?=0.5 MeV to ?=5.4 MeV. The energy dependence of the total cross section is well described by the

J. Smyrski; P. Wüstner; J. T. Balewski; A. Budzanowski; H. Dombrowski; D. Grzonka; L. Jarczyk; M. Jochmann; A. Khoukaz; K. Kilian; P. Kowina; M. Köhler; T. Lister; P. Moskal; W. Oelert; C. Quentmeier; R. Santo; G. Schepers; U. Seddik; T. Sefzick; S. Sewerin; A. Strza?kowski; M. Wolke

2000-01-01

268

Eta Meson Production in Proton-Proton and Nuclear Collisions  

NASA Technical Reports Server (NTRS)

Total cross sections for eta meson production in proton - proton collisions are calculated. The eta meson is mainly produced via decay of the excited nucleon resonance at 1535 MeV. A scalar quantum field theory is used to calculate cross sections, which also include resonance decay. Comparison between theory and experiment is problematic near threshold when resonance decay is not included. When the decay is included, the comparison between theory and experiment is much better.

Norbury, John W.; Dick, Frank

2008-01-01

269

Source characterization and modeling development for monoenergetic-proton radiography experiments on OMEGA.  

PubMed

A monoenergetic proton source has been characterized and a modeling tool developed for proton radiography experiments at the OMEGA [T. R. Boehly et al., Opt. Comm. 133, 495 (1997)] laser facility. Multiple diagnostics were fielded to measure global isotropy levels in proton fluence and images of the proton source itself provided information on local uniformity relevant to proton radiography experiments. Global fluence uniformity was assessed by multiple yield diagnostics and deviations were calculated to be ?16% and ?26% of the mean for DD and D(3)He fusion protons, respectively. From individual fluence images, it was found that the angular frequencies of ?50 rad(-1) contributed less than a few percent to local nonuniformity levels. A model was constructed using the Geant4 [S. Agostinelli et al., Nuc. Inst. Meth. A 506, 250 (2003)] framework to simulate proton radiography experiments. The simulation implements realistic source parameters and various target geometries. The model was benchmarked with the radiographs of cold-matter targets to within experimental accuracy. To validate the use of this code, the cold-matter approximation for the scattering of fusion protons in plasma is discussed using a typical laser-foil experiment as an example case. It is shown that an analytic cold-matter approximation is accurate to within ?10% of the analytic plasma model in the example scenario. PMID:22755626

Manuel, M J-E; Zylstra, A B; Rinderknecht, H G; Casey, D T; Rosenberg, M J; Sinenian, N; Li, C K; Frenje, J A; Séguin, F H; Petrasso, R D

2012-06-01

270

Source characterization and modeling development for monoenergetic-proton radiography experiments on OMEGA  

NASA Astrophysics Data System (ADS)

A monoenergetic proton source has been characterized and a modeling tool developed for proton radiography experiments at the OMEGA [T. R. Boehly et al., Opt. Comm. 133, 495 (1997)] laser facility. Multiple diagnostics were fielded to measure global isotropy levels in proton fluence and images of the proton source itself provided information on local uniformity relevant to proton radiography experiments. Global fluence uniformity was assessed by multiple yield diagnostics and deviations were calculated to be ~16% and ~26% of the mean for DD and D3He fusion protons, respectively. From individual fluence images, it was found that the angular frequencies of >~50 rad-1 contributed less than a few percent to local nonuniformity levels. A model was constructed using the Geant4 [S. Agostinelli et al., Nuc. Inst. Meth. A 506, 250 (2003)] framework to simulate proton radiography experiments. The simulation implements realistic source parameters and various target geometries. The model was benchmarked with the radiographs of cold-matter targets to within experimental accuracy. To validate the use of this code, the cold-matter approximation for the scattering of fusion protons in plasma is discussed using a typical laser-foil experiment as an example case. It is shown that an analytic cold-matter approximation is accurate to within <~10% of the analytic plasma model in the example scenario.

Manuel, M. J.-E.; Zylstra, A. B.; Rinderknecht, H. G.; Casey, D. T.; Rosenberg, M. J.; Sinenian, N.; Li, C. K.; Frenje, J. A.; Séguin, F. H.; Petrasso, R. D.

2012-06-01

271

Source characterization and modeling development for monoenergetic-proton radiography experiments on OMEGA  

SciTech Connect

A monoenergetic proton source has been characterized and a modeling tool developed for proton radiography experiments at the OMEGA [T. R. Boehly et al., Opt. Comm. 133, 495 (1997)] laser facility. Multiple diagnostics were fielded to measure global isotropy levels in proton fluence and images of the proton source itself provided information on local uniformity relevant to proton radiography experiments. Global fluence uniformity was assessed by multiple yield diagnostics and deviations were calculated to be {approx}16% and {approx}26% of the mean for DD and D{sup 3}He fusion protons, respectively. From individual fluence images, it was found that the angular frequencies of Greater-Than-Or-Equivalent-To 50 rad{sup -1} contributed less than a few percent to local nonuniformity levels. A model was constructed using the Geant4 [S. Agostinelli et al., Nuc. Inst. Meth. A 506, 250 (2003)] framework to simulate proton radiography experiments. The simulation implements realistic source parameters and various target geometries. The model was benchmarked with the radiographs of cold-matter targets to within experimental accuracy. To validate the use of this code, the cold-matter approximation for the scattering of fusion protons in plasma is discussed using a typical laser-foil experiment as an example case. It is shown that an analytic cold-matter approximation is accurate to within Less-Than-Or-Equivalent-To 10% of the analytic plasma model in the example scenario.

Manuel, M. J.-E.; Zylstra, A. B.; Rinderknecht, H. G.; Casey, D. T.; Rosenberg, M. J.; Sinenian, N.; Li, C. K.; Frenje, J. A.; Seguin, F. H.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

2012-06-15

272

In Vivo Proton Beam Range Verification Using Spine MRI Changes  

SciTech Connect

Purpose: In proton therapy, uncertainty in the location of the distal dose edge can lead to cautious treatment plans that reduce the dosimetric advantage of protons. After radiation exposure, vertebral bone marrow undergoes fatty replacement that is visible on magnetic resonance imaging (MRI). This presents an exciting opportunity to observe radiation dose distribution in vivo. We used quantitative spine MRI changes to precisely detect the distal dose edge in proton radiation patients. Methods and Materials: We registered follow-up T1-weighted MRI images to planning computed tomography scans from 10 patients who received proton spine irradiation. A radiation dose-MRI signal intensity curve was created using the lateral beam penumbra in the sacrum. This curve was then used to measure range errors in the lumbar spine. Results: In the lateral penumbra, there was an increase in signal intensity with higher dose throughout the full range of 0-37.5 Gy (RBE). In the distal fall-off region, the beam sometimes appeared to penetrate farther than planned. The mean overshoot in 10 patients was 1.9 mm (95% confidence interval, 0.8-3.1 mm), on the order of the uncertainties inherent to our range verification method. Conclusions: We have demonstrated in vivo proton range verification using posttreatment spine MRI changes. Our analysis suggests the presence of a systematic overshoot of a few millimeters in some proton spine treatments, but the range error does not exceed the uncertainty incorporated into the treatment planning margin. It may be possible to extend our technique to MRI sequences that show early bone marrow changes, enabling adaptive treatment modification.

Gensheimer, Michael F. [Vanderbilt University School of Medicine, Nashville, TN (United States); Yock, Torunn I.; Liebsch, Norbert J.; Sharp, Gregory C.; Paganetti, Harald [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Madan, Neel; Grant, P. Ellen [Department of Radiology, Massachusetts General Hospital, Boston, MA (United States); Bortfeld, Thomas, E-mail: tbortfeld@partners.or [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States)

2010-09-01

273

Technical Note: Spatial resolution of proton tomography: Impact of air gap between patient and detector  

SciTech Connect

Purpose: Proton radiography and tomography were investigated since the early 1970s because of its low radiation dose, high density resolution, and ability to image directly proton stopping power. However, spatial resolution is still a limiting factor. In this note, preliminary results of the impact of an air gap between detector system and patient on spatial resolution are presented. Methods: Spatial resolution of proton radiography and tomography is governed by multiple Coulomb scattering (MCS) of the protons in the patient. In this note, the authors employ Monte Carlo simulations of protons traversing a 20 cm thick water box. Entrance and exit proton coordinate measurements were simulated for improved spatial resolution. The simulations were performed with and without a 5 cm air gap in front of and behind the patient. Loss of spatial resolution due to the air gap was studied for protons with different initial angular confusion. Results: It was found that spatial resolution is significantly deteriorated when a 5 cm air gap between the position sensitive detector and the patient is included. For a perfect parallel beam spatial resolution worsens by about 40%. Spatial resolution is getting worse with increasing angular confusion and can reach 80%. Conclusions: When proton radiographies are produced by measuring the entrance and exit coordinates of the protons in front of and behind the patient the air gap between the detector and the patient can significantly deteriorate the spatial resolution of the system by up to 80%. An alternative would be to measure in addition to the coordinates also the exit and entrance angles of each proton. In principle, using the air gap size and proton angle, images can be reconstructed with the same spatial resolution than without air gap.

Schneider, Uwe; Besserer, Juergen; Hartmann, Matthias [Vetsuisse Faculty, University of Zuerich, Winterthurerstrasse 260, 8057 Zuerich (Switzerland) and Radiotherapy Hirslanden AG, Rain 34, 5000 Aarau (Switzerland); Radiotherapy Hirslanden AG, Rain 34, 5000 Aarau (Switzerland)

2012-02-15

274

Recent results on the development of a proton computed tomography system  

NASA Astrophysics Data System (ADS)

Proton Computed Tomography (pCT) is a medical imaging technique based on the use of proton beams with energies above 200 MeV to directly measure stopping power distributions inside the tissue volume. PRIMA (PRoton IMAging) is an Italian collaboration working on the development of a pCT scanner based on a tracker and a calorimeter to measure single protons trajectory and residual energy. The tracker is composed of four planes of silicon microstrip detectors to measure proton entry and exit positions and angles. Residual energy is measured by a calorimeter composed of YAG:Ce scintillating crystals. A first prototype of pCT scanner, with an active area of about 5×5 cm2, has been constructed and characterized with 60 MeV protons at the INFN Laboratori Nazionali del Sud, Catania (Italy) and with 180 MeV protons at Svedberg Laboratory, Uppsala (Sweden). A new pre-clinical prototype with an extended active area up to 20×5 cm2, real time data acquisition and a data rate up to 1 MHz is under development. A description of the two prototypes will be presented together with first results concerning tomographic image reconstruction.

Civinini, C.; Bruzzi, M.; Bucciolini, M.; Carpinelli, M.; Cirrone, G. A. P.; Cuttone, G.; Lo Presti, D.; Pallotta, S.; Pugliatti, C.; Randazzo, N.; Romano, F.; Scaringella, M.; Sipala, V.; Stancampiano, C.; Talamonti, C.; Vanzi, E.; Zani, M.

2013-12-01

275

Interplanetary Proton Model: JPL 1991  

NASA Technical Reports Server (NTRS)

This study was carried out to increase the acuracy and energy range of predictive models of interplanetary proton fluences. Such an estimate is often needed when spacecraft spend a signigicant amount of time in the interplanetary environmnet.

Feynman, J.; Spitale, G.; Wang, J.

1993-01-01

276

Proton Radiotherapy for Pediatric Sarcoma  

PubMed Central

Pediatric sarcomas represent a distinct group of pathologies, with approximately 900 new cases per year in the United States alone. Radiotherapy plays an integral role in the local control of these tumors, which often arise adjacent to critical structures and growing organs. The physical properties of proton beam radiotherapy provide a distinct advantage over standard photon radiation by eliminating excess dose deposited beyond the target volume, thereby reducing both the dose of radiation delivered to non-target structures as well as the total radiation dose delivered to a patient. Dosimetric studies comparing proton plans to IMRT and 3D conformal radiation have demonstrated the superiority of protons in numerous pediatric malignancies and data on long-term clinical outcomes and toxicity is emerging. In this article, we review the existing clinical and dosimetric data regarding the use of proton beam radiation in malignant bone and soft tissue sarcomas.

Ladra, Matthew M.; Yock, Torunn I.

2014-01-01

277

Proton-Coupled Electron Transfer  

SciTech Connect

Proton-Coupled Electron Transfer (PCET) describes reactions in which there is a change in both electron and proton content between reactants and products. It originates from the influence of changes in electron content on acid?base properties and provides a molecular-level basis for energy transduction between proton transfer and electron transfer. Coupled electron?proton transfer or EPT is defined as an elementary step in which electrons and protons transfer from different orbitals on the donor to different orbitals on the acceptor. There is (usually) a clear distinction between EPT and H-atom transfer (HAT) or hydride transfer, in which the transferring electrons and proton come from the same bond. Hybrid mechanisms exist in which the elementary steps are different for the reaction partners. EPT pathways such as PhO•/PhOH exchange have much in common with HAT pathways in that electronic coupling is significant, comparable to the reorganization energy with H{sub DA} ~ ?. Multiple-Site Electron?Proton Transfer (MS-EPT) is an elementary step in which an electron?proton donor transfers electrons and protons to different acceptors, or an electron?proton acceptor accepts electrons and protons from different donors. It exploits the long-range nature of electron transfer while providing for the short-range nature of proton transfer. A variety of EPT pathways exist, creating a taxonomy based on what is transferred, e.g., 1e{sup -}/2H{sup +} MS-EPT. PCET achieves “redox potential leveling” between sequential couples and the buildup of multiple redox equivalents, which is of importance in multielectron catalysis. There are many examples of PCET and pH-dependent redox behavior in metal complexes, in organic and biological molecules, in excited states, and on surfaces. Changes in pH can be used to induce electron transfer through films and over long distances in molecules. Changes in pH, induced by local electron transfer, create pH gradients and a driving force for long-range proton transfer in Photosysem II and through other biological membranes. In EPT, simultaneous transfer of electrons and protons occurs on time scales short compared to the periods of coupled vibrations and solvent modes. A theory for EPT has been developed which rationalizes rate constants and activation barriers, includes temperature- and driving force (?G)-dependences implicitly, and explains kinetic isotope effects. The distance-dependence of EPT is dominated by the short-range nature of proton transfer, with electron transfer being far less demanding.Changes in external pH do not affect an EPT elementary step. Solvent molecules or buffer components can act as proton donor acceptors, but individual H2O molecules are neither good bases (pK{sub a}(H{sub 3}O{sup +}) = ?1.74) nor good acids (pK{sub a}(H{sub 2}O) = 15.7). There are many examples of mechanisms in chemistry, in biology, on surfaces, and in the gas phase which utilize EPT. PCET and EPT play critical roles in the oxygen evolving complex (OEC) of Photosystem II and other biological reactions by decreasing driving force and avoiding high-energy intermediates.

Weinberg, Dave; Gagliardi, Christopher J.; Hull, Jonathan F; Murphy, Christine Fecenko; Kent, Caleb A.; Westlake, Brittany C.; Paul, Amit; Ess, Daniel H; McCafferty, Dewey Granville; Meyer, Thomas J

2012-01-01

278

Parametric Model for Astrophysical Proton-Proton Interactions and Applications  

SciTech Connect

Observations of gamma-rays have been made from celestial sources such as active galaxies, gamma-ray bursts and supernova remnants as well as the Galactic ridge. The study of gamma rays can provide information about production mechanisms and cosmic-ray acceleration. In the high-energy regime, one of the dominant mechanisms for gamma-ray production is the decay of neutral pions produced in interactions of ultra-relativistic cosmic-ray nuclei and interstellar matter. Presented here is a parametric model for calculations of inclusive cross sections and transverse momentum distributions for secondary particles--gamma rays, e{sup {+-}}, {nu}{sub e}, {bar {nu}}{sub e}, {nu}{sub {mu}} and {bar {nu}}{sub {mu}}--produced in proton-proton interactions. This parametric model is derived on the proton-proton interaction model proposed by Kamae et al.; it includes the diffraction dissociation process, Feynman-scaling violation and the logarithmically rising inelastic proton-proton cross section. To improve fidelity to experimental data for lower energies, two baryon resonance excitation processes were added; one representing the {Delta}(1232) and the other multiple resonances with masses around 1600 MeV/c{sup 2}. The model predicts the power-law spectral index for all secondary particle to be about 0.05 lower in absolute value than that of the incident proton and their inclusive cross sections to be larger than those predicted by previous models based on the Feynman-scaling hypothesis. The applications of the presented model in astrophysics are plentiful. It has been implemented into the Galprop code to calculate the contribution due to pion decays in the Galactic plane. The model has also been used to estimate the cosmic-ray flux in the Large Magellanic Cloud based on HI, CO and gamma-ray observations. The transverse momentum distributions enable calculations when the proton distribution is anisotropic. It is shown that the gamma-ray spectrum and flux due to a pencil beam of protons varies drastically with viewing angle. A fanned proton jet with a Gaussian intensity profile impinging on surrounding material is given as a more realistic example. As the observer is moved off the jet axis, the peak of the spectrum is moved to lower energies.

Karlsson, Niklas; /Royal Inst. Tech., Stockholm

2008-01-29

279

IMAGES, IMAGES, IMAGES  

SciTech Connect

The role of images of information (charts, diagrams, maps, and symbols) for effective presentation of facts and concepts is expanding dramatically because of advances in computer graphics technology, increasingly hetero-lingual, hetero-cultural world target populations of information providers, the urgent need to convey more efficiently vast amounts of information, the broadening population of (non-expert) computer users, the decrease of available time for reading texts and for decision making, and the general level of literacy. A coalition of visual performance experts, human engineering specialists, computer scientists, and graphic designers/artists is required to resolve human factors aspects of images of information. The need for, nature of, and benefits of interdisciplinary effort are discussed. The results of an interdisciplinary collaboration are demonstrated in a product for visualizing complex information about global energy interdependence. An invited panel will respond to the presentation.

Marcus, A.

1980-07-01

280

High intensity protons in RHIC  

SciTech Connect

During the 2012 summer shutdown a pair of electron lenses will be installed in RHIC, allowing the beam-beam parameter to be increased by roughly 50 percent. To realize the corresponding luminosity increase bunch intensities have to be increased by 50 percent, to 2.5 {center_dot} 10{sup 11} protons per bunch. We list the various RHIC subsystems that are most affected by this increase, and propose beam studies to ensure their readiness. The proton luminosity in RHIC is presently limited by the beam-beam effect. To overcome this limitation, electron lenses will be installed in IR10. With the help of these devices, the headon beam-beam kick experienced during proton-proton collisions will be partially compensated, allowing for a larger beam-beam tuneshift at these collision points, and therefore increasing the luminosity. This will be accomplished by increasing the proton bunch intensity from the presently achieved 1.65 {center_dot} 10{sup 11} protons per bunch in 109 bunches per beam to 2.5 {center_dot} 10{sup 11}, thus roughly doubling the luminosity. In a further upgrade we aim for bunch intensities up to 3 {center_dot} 10{sup 11} protons per bunch. With RHIC originally being designed for a bunch intensity of 1 {center_dot} 10{sup 11} protons per bunch in 56 bunches, this six-fold increase in the total beam intensity by far exceeds the design parameters of the machine, and therefore potentially of its subsystems. In this note, we present a list of major subsystems that are of potential concern regarding this intensity upgrade, show their demonstrated performance at present intensities, and propose measures and beam experiments to study their readiness for the projected future intensities.

Montag, C.; Ahrens& #44; L.; Blaskiewicz& #44; M.; Brennan& #44; J.M.; Drees& #44; K.A.; Fischer& #44; W.; Huang& #44; H.; Minty& #44; M.; Robert-Demolaize& #44; G.; Thieberger& #44; P.; Yip& #44; K.

2012-01-05

281

Proton driver power supply system  

SciTech Connect

This paper describes magnet power supply system for a proposed Proton Driver at Fermilab. The magnet power supply system consists of resonant dipole/quadrupole power supply system, quadrupole tracking, dipole correction (horizontal and vertical) and sextupole power supply systems. This paper also describes preliminary design of the power distribution system supplying 13.8 kV power to all proton Driver electrical systems.

C. Jach and D. Wolff

2002-06-03

282

Recent Solar-Proton Fluxes  

NASA Technical Reports Server (NTRS)

The event-integrated fluences of energetic solar protons up to 2004 at the Earth have been determined and compared to previous data. The current solar cycle has been very active, and very large fluxes of solar protons have been observed that have had serious effects in the solar system and will have produced many radionuclides in the surfaces of meteorites. Such huge events are not expected again until about 2008 or 2009.

Reedy, R. C.

2005-01-01

283

Proton aurora and substorm intensifications  

Microsoft Academic Search

Ground based measurements from the CANOPUS array of meridian scanning photometers and precipitating ion and electron data from the DMSP F9 satellite show that the electron arc which brightens to initiate substorms intensifications is formed within a region of intense proton precipitation that is well equatorward (about 4-6 deg) of the nightside open-closed field line boundary. The precipitating protons are

J. C. Samson; L. R. Lyons; P. T. Newell; F. Creutzberg; B. Xu

1992-01-01

284

Effect of target composition on proton acceleration in ultraintense laser-thin foil interaction  

NASA Astrophysics Data System (ADS)

The interactions of ultraintense circularly polarized laser pulses with a mixed solid target and a double-layer target are studied by two-dimensional particle-in-cell simulations. Different carbon and proton compositions in the targets are used in the simulations. It is shown that the proton acceleration mechanisms in both targets are very sensitive to the ion density ratios between protons and carbon ions. For a mixed solid target, a relatively low proton density gives rise to monoenergetic peaks in the proton energy spectrum while a high proton density leads to a large cut-off energy and wide energy spread. With the increase of the ratio, the so-called directed-Coulomb-explosion becomes dominated over the radiation pressure. Surprisingly, for a double-layer target with a front proton layer and an ultrathin rear carbon layer, a highly monoenergetic proton beam with a peak energy of 1.7 GeV/u, an energy spread of ~4%, and a divergency angle of 2° can be obtained, which might have diverse applications in medical therepy and proton imaging in future.

Liu, Qingcao; Liu, Meng; Yu, Tongpu; Ding, Pengji; Liu, Zuoye; Sun, Shaohua; Liu, Xiaoliang; Lu, Xing; Guo, Zeqin; Hu, Bitao

2012-09-01

285

Characterization of multiterawatt laser-solid interactions for proton acceleration  

NASA Astrophysics Data System (ADS)

A comprehensive characterization of experimental parameters in a study of proton acceleration by short-pulse laser-solid interactions at intensities up to 1019 W cm-2 is reported. Laser pulse and prepulse conditions were measured, with a contrast ratio of the order of 10-6 obtained. The focused laser intensity was experimentally calibrated using a time-of-flight spectrometer to resolve the stages of ionization of a target gas. By comparing the measured ion yields with predictions of an atomic tunneling ionization model a factor of 1.5 uncertainty in the focused intensity was determined. Drive mechanisms for mounting solid targets with thickness in the range of 0.2 to 125 ?m have been developed for use with high-repetition rate lasers. A retro-focus imaging system has also been implemented to position the target relative to the laser focus. The techniques have been applied to study proton acceleration as a function of various laser and target parameters. Measurements of the energy distribution of protons as a function of laser intensity are presented for both mylar and Al targets. A maximum proton energy of 1.5 MeV was observed. A compilation of recent results from a number of laser systems on the conversion efficiency of laser energy to protons is discussed. By comparison, an efficiency of about 0.7% for the present study is encouraging for future tabletop-laser-based ion acceleration.

McKenna, P.; Ledingham, K. W. D.; Spencer, I.; McCany, T.; Singhal, R. P.; Ziener, C.; Foster, P. S.; Divall, E. J.; Hooker, C. J.; Neely, D.; Langley, A. J.; Clarke, R. J.; Norreys, P. A.; Krushelnick, K.; Clark, E. L.

2002-12-01

286

Measured proton sensitivities of bubble detectors.  

PubMed

The neutron dose equivalent in aircraft is measured using commercial bubble detectors, but at high altitudes there are not only neutrons but also protons. Bubble detectors have been used because they are considered not to be sensitive to protons, but this has been the subject of only a few studies. In this study, by irradiating bubble detectors with energetic protons, the detectors' responses to protons were observed. Bubbles were clearly formed by protons, but the proton sensitivities were one order of magnitude smaller than the neutron sensitivities. Thus, counts of protons can be ignored in neutron measurements in aircraft. PMID:15266070

Takada, Masashi; Kitamura, Hisashi; Koi, Tatsumi; Nakamura, Takashi; Fujitaka, Kazunobu

2004-01-01

287

Generation of proton aurora by magnetosonic waves.  

PubMed

Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2-10?keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora. PMID:24898626

Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

2014-01-01

288

Generation of proton aurora by magnetosonic waves  

PubMed Central

Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2–10?keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora.

Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

2014-01-01

289

Proton proton multiplicity distributions at the Relativistic Heavy Ion Collider  

NASA Astrophysics Data System (ADS)

Measurements of global charged particle production in proton-proton collisions were performed using the PHOBOS detector at the Relativistic Heavy Ion Collider. Included is the first published measurement of the charged particle pseudorapidity densities at s = 410GeV. Both s = 410 and 200GeV measurements extend +/-5.4 units in pseudorapidity from 0. This is a greater pseudorapidity range than any previously available result at s = 200GeV. Each measurement was repeated for the total inelastic and non-single diffractive cross sections and with respect to the observed charged particle multiplicity in the PHOBOS Octagon detector. Comparisons to previously existing proton-proton collision data were made including direct comparisons to previously existing s = 200GeV proton-antiproton collisions. There exists good agreement among the inelastic results, but the PHOBOS non-single diffractive result is ˜10% higher at mid-rapidity. Possible explanations for this discrepancy are studied. The slopes of the charged particle pseudorapidity distributions were determined over a common fractional range of the beam rapidity. Total charged particle yields for the inelastic and non-single diffractive cross sections were calculated for both the total distribution and with respect to the PHOBOS Octagon observed charged particle multiplicity. A common growth in the slope with respect to increasing total charged particle yield of each Observed multiplicity's distribution scaled by the average distribution yield is observed. Similar slopes in previously existing data demonstrate this scaling over s = 23.4 to 900GeV. Comparisons to heavy ion results in the PHOBOS detector are made. The matching of centrality binned Gold-Gold and Copper-Copper collisions with similar total charged particle yielding observed multiplicity selected proton-proton data is done. The charged particle pseudorapidity distributions of such matched data show a striking similarity.

Sagerer, Joseph F.

290

Computing proton dose to irregularly moving targets.  

PubMed

Purpose: While four-dimensional computed tomography (4DCT) and deformable registration can be used to assess the dose delivered to regularly moving targets, there are few methods available for irregularly moving targets. 4DCT captures an idealized waveform, but human respiration during treatment is characterized by gradual baseline shifts and other deviations from a periodic signal. This paper describes a method for computing the dose delivered to irregularly moving targets based on 1D or 3D waveforms captured at the time of delivery.Methods: The procedure uses CT or 4DCT images for dose calculation, and 1D or 3D respiratory waveforms of the target position at time of delivery. Dose volumes are converted from their Cartesian geometry into a beam-specific radiological depth space, parameterized in 2D by the beam aperture, and longitudinally by the radiological depth. In this new frame of reference, the proton doses are translated according to the motion found in the 1D or 3D trajectory. These translated dose volumes are weighted and summed, then transformed back into Cartesian space, yielding an estimate of the dose that includes the effect of the measured breathing motion. The method was validated using a synthetic lung phantom and a single representative patient CT. Simulated 4DCT was generated for the phantom with 2 cm peak-to-peak motion.Results: A passively-scattered proton treatment plan was generated using 6 mm and 5 mm smearing for the phantom and patient plans, respectively. The method was tested without motion, and with two simulated breathing signals: a 2 cm amplitude sinusoid, and a 2 cm amplitude sinusoid with 3 cm linear drift in the phantom. The tumor positions were equally weighted for the patient calculation. Motion-corrected dose was computed based on the mid-ventilation CT image in the phantom and the peak exhale position in the patient. Gamma evaluation was 97.8% without motion, 95.7% for 2 cm sinusoidal motion, 95.7% with 3 cm drift in the phantom (2 mm, 2%), and 90.8% (3 mm, 3%)for the patient data.Conclusions: We have demonstrated a method for accurately reproducing proton dose to an irregularly moving target from a single CT image. We believe this algorithm could prove a useful tool to study the dosimetric impact of baseline shifts either before or during treatment. PMID:25029239

Phillips, Justin; Gueorguiev, Gueorgui; Shackleford, James A; Grassberger, Clemens; Dowdell, Stephen; Paganetti, Harald; Sharp, Gregory C

2014-08-01

291

Heteronuclear proton assisted recoupling  

PubMed Central

We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular 15N–13C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term between 1H–15N and 1H–13C dipolar couplings to mediate zero- and/or double-quantum 15N–13C recoupling. In particular, using average Hamiltonian theory we derive effective Hamiltonians for PAIN-CP and show that the transfer is mediated by trilinear terms of the form N±C?Hz (ZQ) or N±C±Hz (DQ) depending on the rf field strengths employed. We use analytical and numerical simulations to explain the structure of the PAIN-CP optimization maps and to delineate the appropriate matching conditions. We also detail the dependence of the PAIN-CP polarization transfer with respect to local molecular geometry and explain the observed reduction in dipolar truncation. In addition, we demonstrate the utility of PAIN-CP in structural studies with 15N–13C spectra of two uniformly 13C,15N labeled model microcrystalline proteins—GB1, a 56 amino acid peptide, and Crh, a 85 amino acid domain swapped dimer (MW = 2 × 10.4 kDa). The spectra acquired at high magic angle spinning frequencies (?r/2? > 20 kHz) and magnetic fields (?0H/2? = 700–900 MHz) using moderate rf fields, yield multiple long-distance intramonomer and intermonomer 15N–13C contacts. We use these distance restraints, in combination with the available x-ray structure as a homology model, to perform a calculation of the monomer subunit of the Crh protein.

Paepe, Gael De; Lewandowski, Jozef R.; Loquet, Antoine; Eddy, Matt; Megy, Simon; Bockmann, Anja; Griffin, Robert G.

2011-01-01

292

Heteronuclear proton assisted recoupling.  

PubMed

We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular (15)N-(13)C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term between (1)H-(15)N and (1)H-(13)C dipolar couplings to mediate zero- and?or double-quantum (15)N-(13)C recoupling. In particular, using average Hamiltonian theory we derive effective Hamiltonians for PAIN-CP and show that the transfer is mediated by trilinear terms of the form N(±)C(?)H(z) (ZQ) or N(±)C(±)H(z) (DQ) depending on the rf field strengths employed. We use analytical and numerical simulations to explain the structure of the PAIN-CP optimization maps and to delineate the appropriate matching conditions. We also detail the dependence of the PAIN-CP polarization transfer with respect to local molecular geometry and explain the observed reduction in dipolar truncation. In addition, we demonstrate the utility of PAIN-CP in structural studies with (15)N-(13)C spectra of two uniformly (13)C,(15)N labeled model microcrystalline proteins-GB1, a 56 amino acid peptide, and Crh, a 85 amino acid domain swapped dimer (MW=2×10.4 kDa). The spectra acquired at high magic angle spinning frequencies (?(r)?2?>20 kHz) and magnetic fields (?(0H)?2?=700-900 MHz) using moderate rf fields, yield multiple long-distance intramonomer and intermonomer (15)N-(13)C contacts. We use these distance restraints, in combination with the available x-ray structure as a homology model, to perform a calculation of the monomer subunit of the Crh protein. PMID:21384999

De Paëpe, Gaël; Lewandowski, Józef R; Loquet, Antoine; Eddy, Matt; Megy, Simon; Böckmann, Anja; Griffin, Robert G

2011-03-01

293

Heteronuclear proton assisted recoupling  

NASA Astrophysics Data System (ADS)

We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular 15N-13C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term between 1H-15N and 1H-13C dipolar couplings to mediate zero- and/or double-quantum 15N-13C recoupling. In particular, using average Hamiltonian theory we derive effective Hamiltonians for PAIN-CP and show that the transfer is mediated by trilinear terms of the form N+/-C-/+Hz (ZQ) or N+/-C+/-Hz (DQ) depending on the rf field strengths employed. We use analytical and numerical simulations to explain the structure of the PAIN-CP optimization maps and to delineate the appropriate matching conditions. We also detail the dependence of the PAIN-CP polarization transfer with respect to local molecular geometry and explain the observed reduction in dipolar truncation. In addition, we demonstrate the utility of PAIN-CP in structural studies with 15N-13C spectra of two uniformly 13C,15N labeled model microcrystalline proteins--GB1, a 56 amino acid peptide, and Crh, a 85 amino acid domain swapped dimer (MW = 2 × 10.4 kDa). The spectra acquired at high magic angle spinning frequencies (?r/2? > 20 kHz) and magnetic fields (?0H/2? = 700-900 MHz) using moderate rf fields, yield multiple long-distance intramonomer and intermonomer 15N-13C contacts. We use these distance restraints, in combination with the available x-ray structure as a homology model, to perform a calculation of the monomer subunit of the Crh protein.

Paëpe, Gaël De; Lewandowski, Józef R.; Loquet, Antoine; Eddy, Matt; Megy, Simon; Böckmann, Anja; Griffin, Robert G.

2011-03-01

294

Imaging Prostatic Lipids to Distinguish Aggressive Prostate Cancer.  

National Technical Information Service (NTIS)

In this application, we propose to build upon our current work to determine the association between fatty acid synthase (FAS) overexpression and intraprostatic fat as measured by in-vivo imaging using proton magnetic resonance spectroscopy imaging in the ...

J. Shannon

2013-01-01

295

Spin matrix elements for the elastic proton-proton and proton-antiproton collisions  

Microsoft Academic Search

Motivated by the present extensive RHIC (BNL) spin program and further PAX\\u000aproject at FAIR, we study the possibility of explicit reconstruction of full\\u000aset of helicity amplitudes by joint consideration of elastic proton-proton and\\u000aproton-antiproton scattering. Procedure is based on the derivative relations\\u000afor the helicity amplitudes, explicit parametrization of the leading spin\\u000anon-flip amplitudes and crossing - symmetry

V. A. Okorokov; S. B. Nurushev

2007-01-01

296

A calcineurin homologous protein is required for sodium-proton exchange events in the C. elegans intestine  

PubMed Central

Caenorhabditis elegans defecation is a rhythmic behavior, composed of three sequential muscle contractions, with a 50-s periodicity. The motor program is driven by oscillatory calcium signaling in the intestine. Proton fluxes, which require sodium-proton exchangers at the apical and basolateral intestinal membranes, parallel the intestinal calcium flux. These proton shifts are critical for defecation-associated muscle contraction, nutrient uptake, and longevity. How sodium-proton exchangers are activated in time with intestinal calcium oscillation is not known. The posterior body defecation contraction mutant (pbo-1) encodes a calcium-binding protein with homology to calcineurin homologous proteins, which are putative cofactors for mammalian sodium-proton exchangers. Loss of pbo-1 function results in a weakened defecation muscle contraction and a caloric restriction phenotype. Both of these phenotypes also arise from dysfunctions in pH regulation due to mutations in intestinal sodium-proton exchangers. Dynamic, in vivo imaging of intestinal proton flux in pbo-1 mutants using genetically encoded pH biosensors demonstrates that proton movements associated with these sodium-proton exchangers are significantly reduced. The basolateral acidification that signals the first defecation motor contraction is scant in the mutant compared with a normal animal. Luminal and cytoplasmic pH shifts are much reduced in the absence of PBO-1 compared with control animals. We conclude that pbo-1 is required for normal sodium-proton exchanger activity and may couple calcium and proton signaling events.

Wagner, Jamie; Allman, Erik; Taylor, Ashley; Ulmschneider, Kiri; Kovanda, Timothy; Ulmschneider, Bryne; Nehrke, Keith

2011-01-01

297

Focusing of short-pulse high-intensity laser-accelerated proton beams  

NASA Astrophysics Data System (ADS)

Recent progress in generating high-energy (>50MeV) protons from intense laser-matter interactions (1018-1021Wcm-2 refs , , , , , , ) has opened up new areas of research, with applications in radiography, oncology, astrophysics, medical imaging, high-energy-density physics, and ion-proton beam fast ignition. With the discovery of proton focusing with curved surfaces, rapid advances in these areas will be driven by improved focusing technologies. Here we report on the first investigation of the generation and focusing of a proton beam using a cone-shaped target. We clearly show that the focusing is strongly affected by the electric fields in the beam in both open and enclosed (cone) geometries, bending the trajectories near the axis. Also in the cone geometry, a sheath electric field effectively `channels' the proton beam through the cone tip, substantially improving the beam focusing properties. These results agree well with particle simulations and provide the physics basis for many future applications.

Bartal, Teresa; Foord, Mark E.; Bellei, Claudio; Key, Michael H.; Flippo, Kirk A.; Gaillard, Sandrine A.; Offermann, Dustin T.; Patel, Pravesh K.; Jarrott, Leonard C.; Higginson, Drew P.; Roth, Markus; Otten, Anke; Kraus, Dominik; Stephens, Richard B.; McLean, Harry S.; Giraldez, Emilio M.; Wei, Mingsheng S.; Gautier, Donald C.; Beg, Farhat N.

2012-02-01

298

Proton-proton correlations in dp and 16Op interactions  

NASA Astrophysics Data System (ADS)

Correlations between two protons emitted in dp and 16Op collisions at momenta 3.3 GeV/c and 52.6 GeV/c, respectively, are presented. The experimental data have been obtained using the one metre hydrogen bubble chamber exposed to nuclear beams from the synchrophasotron, JINR, Dubna. Data show a clear interference effect as expected for identical fermions. A Gaussian parametrization is used to determine the size of the proton emission source. The root mean square radius of the proton source calculated from the correlation function has been found to be equal to (2.10{-0.35/+0.43}) fm and (2.67{-0.38/+0.54}) fm for d and 16O respectively. It agrees with the known radii of these nuclei.

Glagolev, Viktor V.; Martinská, Gabriela; Mušinský, Jan; Urbán, Jozef; Olimov, Khosim; Yuldashev, Anvar A.

2011-12-01

299

Low Velocity Proton Stopping in Negative Hydrogen-Proton Mixtures  

NASA Astrophysics Data System (ADS)

We consider a charge neutral plasma target built on binary ionic mixtures (BIM) with classical electrons. Electron and ion contributions to the proton projectile low velocity ion slowing down (LIVSD) for projectile velocity Vpprotons in any proportion. Proton LIVSD quantitatively documents a monotoneous decay of free electron density with the increasing relative proportion of negative hydrogen ions,up to equi-proportionality. Possible diagnostics of low-temperature plasmas with T 3000-4000^oK with total ion density ranging around 10^11 cm-3 are also discussed.

Deutsch, Claude; Bacal, Marthe; Tashev, Bekbolat

2008-11-01

300

Proton-proton Scattering Above 3 GeV/c  

SciTech Connect

A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.

A. Sibirtsev, J. Haidenbauer, H.-W. Hammer S. Krewald ,Ulf-G. Meissner

2010-01-01

301

Spatial correlation of precipitating and trapped protons associated with an isolated substorm  

NASA Astrophysics Data System (ADS)

We compare the global morphology of medium energy (few keV) energetic neutral atom measurements from IMAGE/MENA with proton aurora measurements from IMAGE/FUV and in situ energetic proton data from LANL/SOPA before and during a magnetospheric substorm that commenced at 1245 UT on 19 September 2000. In the hours before substorm onset, several small auroral activations occurred at locations scattered around local midnight. The neutral atom (ENA) emissions increased continuously throughout the substorm growth phase, mimicking the pseudo-breakup behavior seen in the proton aurora and in situ energetic particle data. Half an hour before substorm onset, the rate of ENA flux increase accelerated. The substorm onset is characterized by a rapidly expanding proton aurora brightening starting near 22 magnetic local time. ENA fluxes continued to rise until 30 minutes after onset. Throughout the whole event the local time distribution of ENA and auroral emissions was remarkably similar.

Jahn, J.-M.; Pollock, C. J.; Immel, T. J.; Mende, S. B.

2006-08-01

302

Intramolecular Proton Transfer in Channelrhodopsins  

PubMed Central

Channelrhodopsins serve as photoreceptors that control the motility behavior of green flagellate algae and act as light-gated ion channels when heterologously expressed in animal cells. Here, we report direct measurements of proton transfer from the retinylidene Schiff base in several channelrhodopsin variants expressed in HEK293 cells. A fast outward-directed current precedes the passive channel current that has the opposite direction at physiological holding potentials. This rapid charge movement occurs on the timescale of the M intermediate formation in microbial rhodopsins, including that for channelrhodopsin from Chlamydomonas augustae and its mutants, reported in this study. Mutant analysis showed that the glutamate residue corresponding to Asp85 in bacteriorhodopsin acts as the primary acceptor of the Schiff-base proton in low-efficiency channelrhodopsins. Another photoactive-site residue corresponding to Asp212 in bacteriorhodopsin serves as an alternative proton acceptor and plays a more important role in channel opening than the primary acceptor. In more efficient channelrhodopsins from Chlamydomonas reinhardtii, Mesostigma viride, and Platymonas (Tetraselmis) subcordiformis, the fast current was apparently absent. The inverse correlation of the outward proton transfer and channel activity is consistent with channel function evolving in channelrhodopsins at the expense of their capacity for active proton transport.

Sineshchekov, Oleg A.; Govorunova, Elena G.; Wang, Jihong; Li, Hai; Spudich, John L.

2013-01-01

303

Intramolecular proton transfer in channelrhodopsins.  

PubMed

Channelrhodopsins serve as photoreceptors that control the motility behavior of green flagellate algae and act as light-gated ion channels when heterologously expressed in animal cells. Here, we report direct measurements of proton transfer from the retinylidene Schiff base in several channelrhodopsin variants expressed in HEK293 cells. A fast outward-directed current precedes the passive channel current that has the opposite direction at physiological holding potentials. This rapid charge movement occurs on the timescale of the M intermediate formation in microbial rhodopsins, including that for channelrhodopsin from Chlamydomonas augustae and its mutants, reported in this study. Mutant analysis showed that the glutamate residue corresponding to Asp(85) in bacteriorhodopsin acts as the primary acceptor of the Schiff-base proton in low-efficiency channelrhodopsins. Another photoactive-site residue corresponding to Asp(212) in bacteriorhodopsin serves as an alternative proton acceptor and plays a more important role in channel opening than the primary acceptor. In more efficient channelrhodopsins from Chlamydomonas reinhardtii, Mesostigma viride, and Platymonas (Tetraselmis) subcordiformis, the fast current was apparently absent. The inverse correlation of the outward proton transfer and channel activity is consistent with channel function evolving in channelrhodopsins at the expense of their capacity for active proton transport. PMID:23442959

Sineshchekov, Oleg A; Govorunova, Elena G; Wang, Jihong; Li, Hai; Spudich, John L

2013-02-19

304

The Spin of the Proton  

SciTech Connect

doi: http://dx.doi.org/10.1016/j.ppnp.2007.12.039
The twenty years since the announcement of the proton spin crisis by the European Muon Collaboration has seen tremendous progress in our knowledge of the distribution of spin within the proton. The problem is reviewed, beginning with the original data and the suggestion that polarized gluons may play a crucial role in resolving the problem through the U(1) axial anomaly. The discussion continues to the present day where not only have strong limits have been placed on the amount of polarized glue in the proton but the experimental determination of the spin content has become much more precise. It is now clear that the origin of the discrepancy between experiment and the naive expectation of the fraction of spin carried by the quarks and anti-quarks in the proton lies in the non-perturabtive structure of the proton. We explain how the features expected in a modern, relativistic and chirally symmetric description of nucleon str

Thomas, Anthony

2008-07-01

305

Mitochondrial proton and electron leaks  

PubMed Central

Mitochondrial proton and electron leak have a major impact on mitochondrial coupling efficiency and production of reactive oxygen species. In the first part of this chapter, we address the molecular nature of the basal and inducible proton leak pathways, and their physiological importance. The basal leak is unregulated, and a major proportion can be attributed to mitochondrial anion carriers, while the proton leak through the lipid bilayer appears to be minor. The basal proton leak is cell-type specific and correlates with metabolic rate. The inducible leak through the adenine nucleotide translocase (ANT) and uncoupling proteins (UCPs) can be activated by fatty acids, superoxide, or peroxidation products. The physiological role of inducible leak through UCP1 in mammalian brown adipose tissue is heat production, whereas the roles of non-mammalian UCP1 and its paralogous proteins, in particular UCP2 and UCP3, are not yet resolved. The second part of the chapter focuses on the electron leak that occurs in the mitochondrial electron transport chain. Exit of electrons prior to the reduction of oxygen to water at cytochrome c oxidase causes the production of superoxide. As the mechanisms of electron leak are crucial to understanding their physiological relevance, we summarize the mechanisms and topology of electron leak from Complex I and III in studies using isolated mitochondria. We also highlight recent progress and challenges of assessing electron leak in the living cell. Finally, we emphasise the importance of proton and electron leak as therapeutic targets in body weight regulation and insulin secretion.

Jastroch, Martin; Divakaruni, Ajit S.; Mookerjee, Shona; Treberg, Jason R.; Brand, Martin D.

2011-01-01

306

Heavy quark photoproduction in proton-proton collisions  

NASA Astrophysics Data System (ADS)

We calculate the photoproduction of heavy quarks in proton-proton collisions at RHIC, Tevatron, and CERN LHC energies, where the photon reaches energies larger than those accessible at DESY-HERA. The integrated cross section and the rapidity distributions for open charm and bottom production are computed employing sound high energy QCD formalisms. For the linear perturbative QCD approaches we consider both the usual collinear factorization and the k?-factorization formalisms, whereas for the nonlinear QCD (saturation) calculations one considers the Golec-Biernat-Wüsthoff and the Iancu-Itakura-Munier parametrizations for the dipole cross section within the color dipole picture.

Gonçalves, V. P.; Machado, M. V.

2005-01-01

307

Proton-proton scattering contribution to emittance growth  

SciTech Connect

Proton-proton scattering contributes to the emittance growth of the SSC. A formulation is given and used to estimate the mean scattering angle, which is used to determine the contribution to SSC emittance growth resulting from elastic pp scattering. The method is based upon Lorentz invariants, and it permits the determination of the cross-section for scattering in the center of mass (c.m.) system, as well as scattering from a fixed target (f.t.). Also an example is given for the case of electromagnetic pp scattering, which results from single virtual photon exchange.

Garavaglia, T.

1993-05-01

308

Physiologic and Radiographic Evidence of the Distal Edge of the Proton Beam in Craniospinal Irradiation  

SciTech Connect

Purpose: Fatty replacement of bone marrow resulting from radiation therapy can be seen on T1-weighted magnetic resonance (MR) images. We evaluated the radiographic appearance of the vertebral bodies in children treated with proton craniospinal irradiation (CSI) to illustrate the distal edge effect of proton radiotherapy. Methods and Materials: The study cohort consisted of 13 adolescents aged 12-18 years who received CSI with proton radiotherapy at Massachusetts General Hospital. Ten of these patients had reached maximal or near-maximal growth. Proton beam radiation for these 10 patients was delivered to the thecal sac and exiting nerve roots only, whereas the remaining 3 patients had a target volume that included the thecal sac, exiting nerve roots, and entire vertebral bodies. Median CSI dose was 27 [range, 23.4-36] cobalt gray equivalent (CGE) given in 1.8-CGE fractions. Magnetic resonance images of the spine were obtained after completion of radiotherapy. Results: Magnetic resonance images of patients who received proton radiotherapy to the thecal sac only demonstrate a sharp demarcation of hyperintense T1-weighted signal in the posterior aspects of the vertebral bodies, consistent with radiation-associated fatty marrow replacement. Magnetic resonance images of the patients prescribed proton radiotherapy to the entire vertebral column had corresponding hyperintense T1-weighted signal involving the entire vertebral bodies. Conclusion: The sharp delineation of radiation-associated fatty marrow replacement in the vertebral bodies demonstrates the rapid decrease in energy at the edge of the proton beam. This provides evidence for a sharp fall-off in radiation dose and supports the premise that proton radiotherapy spares normal tissues unnecessary irradiation.

Krejcarek, Stephanie C. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Grant, P. Ellen [Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Henson, John W. [Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Pappas Center for Neuro-oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Tarbell, Nancy J. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Yock, Torunn I. [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States)]. E-mail: tyock@partners.org

2007-07-01

309

A compact layout for a 50 GeV proton radiography facility  

SciTech Connect

We describe a new compact layout for a 50 GeV proton radiography facility. The more compact design utilizes two-point extraction from the main ring to drive an optimal 8 view imaging system. The lattice design of both the main ring, and of the corresponding 8.5 GeV booster ring is described. The rings have very good longitudinal stability, which is of interest for other applications of high current proton machines in this energy range.

Neri, F. (Filippo); Mottershead, C. T.; Blind, B. (Barbara); Jason, A. J. (Andrew J.); Walstrom, P. L. (Peter L.); Schulze, M. E. (Martin E.); Rybarcyk, L. J. (Lawrence J.); Wang, T. F. (Tai-Sen F.); Thiessen, H. A.; Colestock, P. L. (Patrick L.),; Prichard, B. (Ben)

2003-01-01

310

Modeling of Proton-Induced CCD Degradation in the Chandra X-Ray Observatory  

NASA Technical Reports Server (NTRS)

Modeling results are presented for proton-induced degradation of charge-coupled devices (CCDs) used in the Advanced CCD Imaging Spectrometer instrument on the Chandra X-Ray Observatory. A methodology is described that provides insights regarding degradation mechanism and on-orbit performance for front-illuminated and back-illuminated CCDs Proton-induced changes in charge transfer inefficiency are modeled. The observed amount of on-orbit degradation can be accounted for using a proton spectrum at the CCD location that is reduced in magnitude by a factor of approx. 1E5 compared to the spectrum incident on the spacecraft.

Lo, D. H.; Srour, J. R.

2003-01-01

311

Polarized proton beams in RHIC  

SciTech Connect

The polarized beam for RHIC is produced in the optically-pumped polarized H{sup -} ion source and then accelerated in Linac to 200 MeV for strip-injection to Booster and further accelerated 24.3 GeV in AGS for injection in RHIC. In 2009 Run polarized protons was successfully accelerated to 250 GeV beam energy. The beam polarization of about 60% at 100 GeV beam energy and 36-42% at 250 GeV beam energy was measured with the H-jet and p-Carbon CNI polarimeters. The gluon contribution to the proton spin was studied in collisions of longitudinally polarized proton beams at 100 x 100 GeV. At 250 x 250 GeV an intermediate boson W production with the longitudinally polarized beams was studied for the first time.

Zelenski, A.

2010-10-04

312

The search for proton decay  

SciTech Connect

The conservation of the quantum number called baryon number, like lepton (or family) number, is an empirical fact even though there are very good reasons to expect otherwise. Experimentalists have been searching for baryon number violating decays of the proton and neutron for decades now without success. Theorists have evolved deep understanding of the relationship between the natural forces in the development of various Grand Unified Theories (GUTs) that nearly universally predict baryon number violating proton decay, or related phenomena like n-{bar n} oscillations. With this in mind, the Proton Decay Working Group reviewed the current experimental and theoretical status of the search for baryon number violation with an eye to the advancement in the next decade.

Haines, T. [Los Alamos National Lab., NM (United States); Kaneyuki, K. [Tokyo Institute of Technology (Japan); McGrew, C. [California Univ., Irvine, CA (United States). Dept. of Physics; Mohapatra, R. [Maryland Univ. (United States). Dept. of Physics; Peterson, E. [Minnesota Univ. (United States). Dept. of Physics; Cline, D.B. [California Univ., Los Angeles, CA (United States). Dept. of Physics

1994-12-31

313

Towards Precision Proton Tomography  

NASA Astrophysics Data System (ADS)

Generalized Patron Distributions (GPDs) contain a wealth of information about hadron structure. Mapping the GPDs will allow one, for the first time, to construct ``tomographic'' images of the nucleon's charge and quark helicity distributions in transverse impact parameter space. GPDs can be accessed through lepton scattering processes such as Deeeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). Different facilities world --wide including HERMES at HERA, CLAS and Hall-A at JLab and COMPASS at CERN have measurements of hard exclusive processes as one of their main focuses of research. In this talk we present an overview of the latest developments in the study of GPDs and newly released results will be also presented. The talk will conclude with prospects of the GPD program at existing and planned machines.

Elouadrhiri, Latifa

2007-04-01

314

Proton aurora and substorm intensifications  

NASA Technical Reports Server (NTRS)

Ground based measurements from the CANOPUS array of meridian scanning photometers and precipitating ion and electron data from the DMSP F9 satellite show that the electron arc which brightens to initiate substorms intensifications is formed within a region of intense proton precipitation that is well equatorward (about 4-6 deg) of the nightside open-closed field line boundary. The precipitating protons are from a population that is energized via Earthward convection from the magnetotail into the dipolar region of the magnetosphere and may play an important role in the formation of the electron arcs leading to substorm intensifications on dipolelike field lines.

Samson, J. C.; Lyons, L. R.; Newell, P. T.; Creutzberg, F.; Xu, B.

1992-01-01

315

Proton aurora and substorm intensifications  

NASA Technical Reports Server (NTRS)

Ground based measurements from the CANOPUS array of meridian scanning photometers and precipitating ion and electron data from the DMSP F9 satellite show that the electron arc which brightens to initiate substorm intensifications is formed within a region of intense proton precipitation that is well equatorward (approximately four to six degrees) of the nightside open-closed field line boundary. The precipitating protons are from a population that is energized via earthward convection from the magnetotail into the dipolar region of the magnetosphere and may play an important role in the formation of the electron arcs leading to substorm intensifications on dipole-like field lines.

Samson, J. C.; Xu, B.; Lyons, L. R.; Newell, P. T.; Creutzberg, F.

1993-01-01

316

Proton interactions with high multiplicity  

SciTech Connect

Project Thermalization is aimed to study the proton-proton interaction with high multiplicity of secondary particles. The region of high multiplicity is especially actual at present. We expect the manifestation of the secondary particle collective behavior at this region. The experimentally measured topological cross section was corrected for apparatus acceptance and detection efficiency. These data are in good agreement with gluon dominance model. The comparison with other models is also done and shows no essential deviations. There is evidence that Bose-Einstein condensation can formed at high total multiplicity region.

Kokoulina, E. S., E-mail: kokoulin@sunse.jinr.ru; Nikitin, V. A.; Petukhov, Y. P. [LHEP, JINR (Russian Federation); Kutov, A. Ya. [Department of Mathematics Komi SC UrD RAS (Russian Federation)

2012-06-15

317

Proton-conducting glass electrolyte.  

PubMed

A new porous glass electrolyte consisting of heteropolyacids, i.e., phosphotungstic acid (PWA) and phosphomolybdic acid, was investigated and was found to yield a remarkably high proton conductivity of 1.014 S cm(-1) at 30 degrees C and 85% relative humidity. This is the first time such a high proton conductivity value has been reported for a heteropolyacid glass membrane. The glass was applied as the electrolyte for an H(2)/O(2) fuel cell, and a maximum power density of 41.5 mW/cm(2) at 32 degrees C was attained using this new PWA-containing electrode. PMID:18081259

Uma, Thanganathan; Nogami, Masayuki

2008-01-15

318

Active interrogation using energetic protons  

SciTech Connect

Energetic proton beams provide an attractive alternative when compared to electromagnetic and neutron beams for active interrogation of nuclear threats because they have large fission cross sections, long mean free paths and high penetration, and they can be manipulated with magnetic optics. We have measured time-dependent cross sections and neutron yields for delayed neutrons and gamma rays using 800 MeV and 4 GeV proton beams with a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Measurements of neutron energies yield suggest a signature unique to fissile material. Results are presented in this paper.

Morris, Christopher L [Los Alamos National Laboratory; Chung, Kiwhan [Los Alamos National Laboratory; Greene, Steven J [Los Alamos National Laboratory; Hogan, Gary E [Los Alamos National Laboratory; Makela, Mark [Los Alamos National Laboratory; Mariam, Fesseha [Los Alamos National Laboratory; Milner, Edward C [Los Alamos National Laboratory; Murray, Matthew [Los Alamos National Laboratory; Saunders, Alexander [Los Alamos National Laboratory; Spaulding, Randy [Los Alamos National Laboratory; Wang, Zhehui [Los Alamos National Laboratory; Waters, Laurie [Los Alamos National Laboratory; Wysocki, Frederick [Los Alamos National Laboratory

2010-01-01

319

Generation and focusing of short pulse high intensity laser accelerated protons  

NASA Astrophysics Data System (ADS)

Much progress has recently been reported in generating MeV energy protons from intense laser-matter interactions, having potential applications in areas such as radiography, oncology, and ion-proton beam fast ignition. Experiments were conducted on the sub-ps LANL Trident laser, where we systematically investigated proton focusing and conversion efficiency from curved surface targets in both open and closed cone-shaped target geometries. We clearly show that the focusing is strongly affected by the electric fields in the beam, bending the trajectories near the axis. We also find that in the cone geometry, a sheath electric field effectively ``channels'' the proton beam through the cone tip, substantially improving the beam focusing properties. The far-field energy and angular distribution of the proton beam were measured using a mesh that images the beam onto a RCF detector. For the cone-shaped targets using a 300 ?m-radius curved surface foil, a 60 ?m diameter proton spot was determined. Proton generation and focusing were modeled using 2-D hybrid PIC simulations, which compared well with RCF data. The proton conversion efficiency varied strongly with the target geometry. Simulations indicate this is due to that charge flow on the structure and the coupling to the hot electrons and electric fields in the plasma.

Foord, Mark E.

2011-11-01

320

Sub-oval proton aurora spots: Mapping relatively to the plasmapause  

NASA Astrophysics Data System (ADS)

Sub-oval proton auroras discovered by the IMAGE spacecraft correlate with EMIC waves (geomagnetic pulsations of the Pc1 range). This means that a common source of the waves and proton precipitation is the ion-cyclotron (IC) instability developing in the vicinity of the equatorial plane. Different forms of the proton auroras reflect different regimes of the IC instability and different conditions in the near-Earth equatorial magnetosphere. To understand what are the conditions for the generation of the sub-oval proton aurora one may map the aurora onto the equatorial plane and compare the projection with some important magnetospheric boundaries. In this report we compare the projection of so-called “proton aurora spots” with the location of the plasmapause. The latter is determined by the plasmapause formation model based on the quasi-interchange instability mechanism. The comparison shows that often the proton aurora spot source is located in the vicinity of the plasmapause or in the cold plasma gradient inside the plasmapause. In some events, the proton aurora spots map well outside the plasmapause. We assume that in the latter case the IC instability develops when westward drifting energetic protons interact with the cold plasma that was earlier detached from the plasmasphere.

Yahnin, A. G.; Yahnina, T. A.; Frey, H.; Pierrard, V.

2013-07-01

321

Proton-radiography-based quality assurance of proton range compensator  

NASA Astrophysics Data System (ADS)

The aim of this work was to study the feasibility of proton radiography (pRad) as a patient-specific range compensator (RC) quality assurance (QA) tool and to validate its clinical utility by performing QA on RCs having three kinds of possible defects. In order to achieve pRad for a single EBT film, proton beam currents were modulated with new weighting factors, maximizing the linearity of optical-density-to-thickness ratio. Two RCs, examined to be accurately manufactured as planned, were selected to estimate the feasibility of our pRad. The optical densities of the EBT film on which the RC was irradiated with the modulated proton beam were digitized to pixel values (pv) and then converted to thickness using a thickness-pv calibration curve. The thickness information on the pRad was compared with plan data that had been extracted from treatment planning system. The mean thickness difference (TD) over the flat RC regions was calculated as 0.39 mm, and the standard deviation as 0.22 mm, and the proton scattering effect was analyzed by step phantom measurement. Even proton scattering effected a TD of over 1 mm in the large gradient region, the percentage of pixels over the acceptance criterion was only within 1.11% and 3.49%, respectively, when a 1 mm distance to agreement tolerance limit was applied. The QA results for both precisely and imprecisely manufactured RCs demonstrated the high potential utility and clinical applicability of the pRad-based RC QA tool.

Park, Seyjoon; Jeong, Chiyoung; Kang, Dong Yun; Shin, Jae-ik; Cho, Sungkoo; Park, Jeong-Hoon; Shin, Dongho; Lim, Young Kyung; Kim, Joo-Young; Min, Byung Jun; Kwak, Jungwon; Lee, Jiseoc; Cho, Seungryong; Kim, Dae-Hyun; Park, Sung Yong; Byeong Lee, Se

2013-09-01

322

Determining the mechanism of cusp proton aurora  

PubMed Central

Earth's cusp proton aurora occurs near the prenoon and is primarily produced by the precipitation of solar energetic (2–10?keV) protons. Cusp auroral precipitation provides a direct source of energy for the high-latitude dayside upper atmosphere, contributing to chemical composition change and global climate variability. Previous studies have indicated that magnetic reconnection allows solar energetic protons to cross the magnetopause and enter the cusp region, producing cusp auroral precipitation. However, energetic protons are easily trapped in the cusp region due to a minimum magnetic field existing there. Hence, the mechanism of cusp proton aurora has remained a significant challenge for tens of years. Based on the satellite data and calculations of diffusion equation, we demonstrate that EMIC waves can yield the trapped proton scattering that causes cusp proton aurora. This moves forward a step toward identifying the generation mechanism of cusp proton aurora.

Xiao, Fuliang; Zong, Qiugang; Su, Zhenpeng; Yang, Chang; He, Zhaoguo; Wang, Yongfu; Gao, Zhonglei

2013-01-01

323

Parton distributions with high energy proton beams  

SciTech Connect

The opportunities for using high energy proton beams to advance our current knowledge in parton distributions are discussed. Highlights from some Fermilab dimuon production experiments with 800 GeV proton beams are presented. Possible future directions are discussed.

Peng, J.C.

1996-12-31

324

Proton Pumps: Mechanism of Action and Applications.  

National Technical Information Service (NTIS)

Recent progress in understanding molecular structures and mechanisms of action of proton pumps has paved the way to their novel applications in biotechnology. Proton pumps, in particular bacteriorhodopsin and ATP synthases, are capable of continuous, rene...

J. K. Lanyi A. Pohorille

2001-01-01

325

Characterization of proton interactions in electronic components  

Microsoft Academic Search

The responses of several np and pn diodes to 30, 100, 200 MeV protons were experimentally characterized. The results are compared with calculations using the HETC code. Well matching proton-induced SEU cross-sections are deduced

B. Doucin; Y. Patin; J. P. Lochard; J. Beaucour; T. Carriere; D. Isabelle; J. Buisson; T. Corbiere; T. Bion

1994-01-01

326

Model for Solar Proton Risk Assessment  

NASA Technical Reports Server (NTRS)

A statistical model for cumulative solar proton event fluences and for worst-case flux during space missions is presented. New features include the solar minimum time period and proton energy spectra that extend to higher energies.

Xapsos, M. A.; Stauffer, C.; Gee, G. B.; Barth, J. L.; Stassinopoulos, E. G.; McGuire, R. E.

2004-01-01

327

Polarized protons and parity violating asymmetries  

SciTech Connect

The potential for utilizing parity violating effects, associated with polarized protons, to study the standard model, proton structure, and new physics at the SPS Collider is summarized. 24 references.

Trueman, T.L.

1984-01-01

328

High energy physics with polarized proton beams  

Microsoft Academic Search

A brief review of the polarization program at the Argonne ZGS is given. Elastic and inelastic proton-proton interactions are discussed including such topics as total cross sections and analyzing power. (AIP)

R. C. Fernow; A. D. Krisch

1981-01-01

329

Proton radiography and fluoroscopy of lung tumors: A Monte Carlo study using patient-specific 4DCT phantoms  

PubMed Central

Purpose: Monte Carlo methods are used to simulate and optimize a time-resolved proton range telescope (TRRT) in localization of intrafractional and interfractional motions of lung tumor and in quantification of proton range variations. Methods: The Monte Carlo N-Particle eXtended (MCNPX) code with a particle tracking feature was employed to evaluate the TRRT performance, especially in visualizing and quantifying proton range variations during respiration. Protons of 230 MeV were tracked one by one as they pass through position detectors, patient 4DCT phantom, and finally scintillator detectors that measured residual ranges. The energy response of the scintillator telescope was investigated. Mass density and elemental composition of tissues were defined for 4DCT data. Results: Proton water equivalent length (WEL) was deduced by a reconstruction algorithm that incorporates linear proton track and lateral spatial discrimination to improve the image quality. 4DCT data for three patients were used to visualize and measure tumor motion and WEL variations. The tumor trajectories extracted from the WEL map were found to be within ?1 mm agreement with direct 4DCT measurement. Quantitative WEL variation studies showed that the proton radiograph is a good representation of WEL changes from entrance to distal of the target. Conclusions:MCNPX simulation results showed that TRRT can accurately track the motion of the tumor and detect the WEL variations. Image quality was optimized by choosing proton energy, testing parameters of image reconstruction algorithm, and comparing to ground truth 4DCT. The future study will demonstrate the feasibility of using the time resolved proton radiography as an imaging tool for proton treatments of lung tumors.

Han, Bin; Xu, X. George; Chen, George T. Y.

2011-01-01

330

Alpha proton x ray spectrometer  

NASA Technical Reports Server (NTRS)

Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

Rieder, Rudi; Waeke, H.; Economou, T.

1994-01-01

331

New interplanetary proton fluence model  

Microsoft Academic Search

A new predictive engineering model for the interplanetary fluence of protons with above 10 MeV and above 30 MeV is described. The data set used is a combination of observations made from the earth's surface and from above the atmosphere between 1956 and 1963 and observations made from spacecraft in the vicinity of earth between 1963 and 1985. The data

Joan Feynman; T. P. Armstrong; L. Dao-Gibner; S. Silverman

1990-01-01

332

Gluon polarization in the proton  

SciTech Connect

We combine heavy-quark renormalization group arguments with our understanding of the nucleon's wave function to deduce a bound on the gluon polarization {Delta}g in the proton. The bound is consistent with the values extracted from spin experiments at COMPASS and RHIC.

Bass, Steven D.; Casey, Andrew; Thomas, Anthony W. [Institute for Theoretical Physics, Universitaet Innsbruck, Technikerstrasse 25, Innsbruck, A-6020 Austria (Austria); CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide SA 5005 (Australia)

2011-03-15

333

High current polarized proton sources  

SciTech Connect

Polarized proton sources are now being used more frequently on linacs. In pulsed operation up to 10 mA of /rvec H//sup +/ and 0.4 mA of /rvec H//sup /minus// have been produced. The present status of these sources, and developments to reach even higher intensities, are reviewed. 39 refs., 1 tab.

Alessi, J.G.

1988-01-01

334

Proton storage ring summer workshop  

Microsoft Academic Search

During the week of August 16, 1976 a Workshop was held at the Los Alamos Scientific Laboratory (LASL) on the Proton Storage Ring (PSR) for the Weapons Neutron Research Facility (WNRF). Written contributions were solicited from each of the participants in the Workshop, and the contributions that were received are presented. The papers do not represent polished or necessarily complete

G. P. Lawrence; R. K. Cooper

1977-01-01

335

^69Kr ?-delayed proton emission  

NASA Astrophysics Data System (ADS)

Proton-rich nuclei beyond the N=Z line play a key role in our understanding of astrophysics, weak-interaction physics, and nuclear structure tests. In particular, the decay of ^69Kr populates states in the proton-unbound nucleus ^69Br. While recent measurements of ^65As and ^69Br have constrained key rp- process waiting points, spectroscopic and structural information remains elusive. An experiment was conducted at GANIL which utilized implant-?-p and ?-? correlations to study physics related to the ? decays of ^69,70,71Kr. Isotopes were implanted into a Si-DSSD, also used to detect decay protons, located at the end of the LISE spectrometer. Coincident ?-rays were measured in surrounding HpGe EXOGAM clovers. We identified 212 ^69Kr implantation-decay events and observed a dominant superallowed ?-decay branch (T1/2=27(3) ms) to the isobaric analog state which decays via 2.97(5) MeV protons to the first excited state in ^68Se. This decay path strongly constrains the spin and mass of ^69Kr.

Rogers, A. M.; Lister, C. J.; Clark, J. A.; Fischer, S. M.; Gros, S.; McCutchan, E. A.; Savard, G.; Seweryniak, D.; Giovinazzo, J.; Blank, B.; Canchel, G.; de France, G.; Grevy, S.; de Oliveira Santos, F.; Stefan, I.; Thomas, J.-C.

2011-10-01

336

Uncertainties in the Proton Lifetime.  

National Technical Information Service (NTIS)

We discuss the masses of the leptoquark bosons m(x) and the proton lifetime in Grand Unified Theories based principally on SU(5). It is emphasized that estimates of m(x) based on the QCD coupling and the fine structure constant are probably more reliable ...

J. Ellis D. V. Nanopoulos S. Rudaz M. K. Gaillard

1980-01-01

337

Fast neutron production from lithium converters and laser driven protons  

NASA Astrophysics Data System (ADS)

Experiments to generate neutrons from the 7Li(p,n)7Be reaction with 60 J, 180 fs laser pulses have been performed at the Texas Petawatt Laser Facility at the University of Texas at Austin. The protons were accelerated from the rear surface of a thin target membrane using the target-normal-sheath-acceleration mechanism. The neutrons were generated in nuclear reactions caused by the subsequent proton bombardment of a pure lithium foil of natural isotopic abundance. The neutron energy ranged up to 2.9 MeV. The total yield was estimated to be 1.6 × 107 neutrons per steradian. An extreme ultra-violet light camera, used to image the target rear surface, correlated variations in the proton yield and peak energy to target rear surface ablation. Calculations using the hydrodynamics code FLASH indicated that the ablation resulted from a laser pre-pulse of prolonged intensity. The ablation severely limited the proton acceleration and neutron yield.

Storm, M.; Jiang, S.; Wertepny, D.; Orban, C.; Morrison, J.; Willis, C.; McCary, E.; Balencourt, P.; Snyder, J.; Chowdhury, E.; Bang, W.; Gaul, E.; Dyer, G.; Ditmire, T.; Freeman, R. R.; Akli, K.

2013-05-01

338

Fast neutron production from lithium converters and laser driven protons  

SciTech Connect

Experiments to generate neutrons from the {sup 7}Li(p,n){sup 7}Be reaction with 60 J, 180 fs laser pulses have been performed at the Texas Petawatt Laser Facility at the University of Texas at Austin. The protons were accelerated from the rear surface of a thin target membrane using the target-normal-sheath-acceleration mechanism. The neutrons were generated in nuclear reactions caused by the subsequent proton bombardment of a pure lithium foil of natural isotopic abundance. The neutron energy ranged up to 2.9 MeV. The total yield was estimated to be 1.6 × 10{sup 7} neutrons per steradian. An extreme ultra-violet light camera, used to image the target rear surface, correlated variations in the proton yield and peak energy to target rear surface ablation. Calculations using the hydrodynamics code FLASH indicated that the ablation resulted from a laser pre-pulse of prolonged intensity. The ablation severely limited the proton acceleration and neutron yield.

Storm, M.; Jiang, S.; Wertepny, D.; Orban, C.; Morrison, J.; Willis, C.; McCary, E.; Balencourt, P.; Snyder, J.; Chowdhury, E.; Freeman, R. R.; Akli, K. [Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210 (United States)] [Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210 (United States); Bang, W.; Gaul, E.; Dyer, G.; Ditmire, T. [Department of Physics, Center for High Energy Density Science, C1510, University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Physics, Center for High Energy Density Science, C1510, University of Texas at Austin, Austin, Texas 78712 (United States)

2013-05-15

339

A model for proton-induced SEU  

Microsoft Academic Search

The authors present a method for predicting proton-induced single-event upset (SEU) rates in devices exposed to given proton fluxes, within a particular spacecraft shielding. The approach uses experimental heavy-ion cross-section data, combined with nuclear reaction calculations, in order to determine the proton-induced SEU cross section versus proton energy relationship. Calculations for two devices, the Fairchild 932422 RAM and the Intel

T. Bion; J. Bourrieau

1989-01-01

340

Electron Emission from Tungsten under Proton Bombardment  

Microsoft Academic Search

The yield of electrons from clean polycrystalline tungsten under bombardment by protons at normal incidence has been measured as a function of proton energy in the range 50 to 225 keV. The maximum value of the yield is 1.65+\\/-0.03 electrons per proton at a proton energy of 125 keV. The tungsten surface was cleaned by flash heating a tungsten ribbon

Ronald I. Ewing

1965-01-01

341

Low-Energy Proton Testing Methodology  

NASA Technical Reports Server (NTRS)

Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

2009-01-01

342

Proton Radiography: Cross Section Measurements and Detector Development  

SciTech Connect

Proton radiography has become an important tool for predicting the performance of stockpiled nuclear weapons. Current proton radiography experiments at LANSCE are confined to relatively small targets on the order of centimeters in size because of the low beam energy. LANL scientists have made radiographs with 12 and 24 GeV protons produced by the accelerator at Brookhaven National Laboratory. These energies are in the range required for hydrotest radiography. The design of a facility for hydrotest radiography requires knowledge of the cross sections for producing high-energy particles in the forward direction, which are incorporated into the Monte Carlo simulation used in designing the beam and detectors. There are few existing measurements of neutron production cross sections for proton-nuclei interactions in the 50 GeV range, and almost no data exist for forward neutron production, especially for heavy target nuclei. Thus the data from the MIPP EMCAL and HCAL, for which our group was responsible, are critical to proton radiography. Since neutrons and photons cannot be focused by magnets, they cause a background “fog” on the images. This problem can be minimized by careful design of the focusing system and detectors. The purpose of our research was to measure forward production of neutrons produced by high-energy proton beams striking a variety of targets. The forward-going particles carry most of the energy from a high-energy proton interaction, so these are the most important to proton radiography. This work was carried out in conjunction with the Fermilab E-907 (MIPP) collaboration. Our group was responsible for designing and building the E907 forward neutron and photon calorimeters. With the support of our Stewardship Science Academic Alliances grants, we were able to design, build, and commission the calorimeters on budget and ahead of schedule. The MIPP experiment accumulated a large amount of data in the first run that ended in early 2006. Our group has almost completed the analysis the forward neutron production data. Large dis-crepancies between our neutron production data and Monte Carlo expectations have been found.

Michael J. Longo; H. R. Gustafson: Durga Rajaram; Turgun Nigmanov

2010-04-16

343

Solar proton fluences at GEO  

NASA Astrophysics Data System (ADS)

NWIP: 14N532 "Observed Proton Fluences over long duration at GEO and Guideline for selection of confidence level in statistical model of Solar Proton Fluences" was approved. 1. Background:Solar energetic protons (SEP) degrade solar panels of GEO spacecrafts. Today, mission lives of many GEO satellites are longer than 11 years. At the end of its mission, solar panel of such satellite outputs more power than estimated. This suggests that today's statistical SEP models predict SEP harsher than natural environment. 2. Purpose:To estimate "proper" proton fluences for the solar cell degradation over long duration at GEO is our goal. This project is for engineering community, and its benefits are adapted to satellite manufactures of the world. 3.Outline of estimation (1) Prepare time-series observed proton daily fluences at GEO. (2) Calculate n-year fluences by integrating daily fluences by shifting the integrating window day-by-day. (3) Select maximum of set of the integrated fluences as the estimated fluences for the n-year mission period. (4) Compare the estimated fluences with confidence level of statistical SEP models. Drs Goka and Kazama already orally presented this method, and their paper is in press. 4.Status at ISO WG4 (1) Project participants of 14N532 are France, Japan, Russia, Ukraine, USA and China. (2) WD is under study. (3) Next target date is 1/23/2009 for CD. To meet the request by world satellite manufactures, namely practical guideline for confidence level, NWIP will be registered as the TS quickly. And actual result will be accumulated then promote to IS, if beneficial.

Ikeda, Masahiko; Goka, Tateo; Kazama, Yoichi

344

The size of the proton.  

PubMed

The proton is the primary building block of the visible Universe, but many of its properties-such as its charge radius and its anomalous magnetic moment-are not well understood. The root-mean-square charge radius, r(p), has been determined with an accuracy of 2 per cent (at best) by electron-proton scattering experiments. The present most accurate value of r(p) (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants. This value is based mainly on precision spectroscopy of atomic hydrogen and calculations of bound-state quantum electrodynamics (QED; refs 8, 9). The accuracy of r(p) as deduced from electron-proton scattering limits the testing of bound-state QED in atomic hydrogen as well as the determination of the Rydberg constant (currently the most accurately measured fundamental physical constant). An attractive means to improve the accuracy in the measurement of r(p) is provided by muonic hydrogen (a proton orbited by a negative muon); its much smaller Bohr radius compared to ordinary atomic hydrogen causes enhancement of effects related to the finite size of the proton. In particular, the Lamb shift (the energy difference between the 2S(1/2) and 2P(1/2) states) is affected by as much as 2 per cent. Here we use pulsed laser spectroscopy to measure a muonic Lamb shift of 49,881.88(76) GHz. On the basis of present calculations of fine and hyperfine splittings and QED terms, we find r(p) = 0.84184(67) fm, which differs by 5.0 standard deviations from the CODATA value of 0.8768(69) fm. Our result implies that either the Rydberg constant has to be shifted by -110 kHz/c (4.9 standard deviations), or the calculations of the QED effects in atomic hydrogen or muonic hydrogen atoms are insufficient. PMID:20613837

Pohl, Randolf; Antognini, Aldo; Nez, François; Amaro, Fernando D; Biraben, François; Cardoso, João M R; Covita, Daniel S; Dax, Andreas; Dhawan, Satish; Fernandes, Luis M P; Giesen, Adolf; Graf, Thomas; Hänsch, Theodor W; Indelicato, Paul; Julien, Lucile; Kao, Cheng-Yang; Knowles, Paul; Le Bigot, Eric-Olivier; Liu, Yi-Wei; Lopes, José A M; Ludhova, Livia; Monteiro, Cristina M B; Mulhauser, Françoise; Nebel, Tobias; Rabinowitz, Paul; Dos Santos, Joaquim M F; Schaller, Lukas A; Schuhmann, Karsten; Schwob, Catherine; Taqqu, David; Veloso, João F C A; Kottmann, Franz

2010-07-01

345

Experimental Study of Proton Acceleration from Ultra Intense Laser Matter Interactions  

NASA Astrophysics Data System (ADS)

This dissertation describes proton and ion acceleration measurements from high intensity (˜ 1019 Wcm-2) laser interactions with thin foil targets. Protons and ions accelerated from the back surface of a target driven by a high intensity laser are detected using solid-state nuclear track detector CR39. A simple digital imaging technique, with an adjustable halogen light source shined on CR39 and use of a digital camera with suitable f-number and exposure time, is used to detect particles tracks. This new technique improves the quality 2D image with vivid track patterns in CR39. Our technique allows us to quickly record and sort CR39 pieces for further analysis. This is followed by detailed quantitative information on the protons and ions. Protons and multicharged ions generated from high-intensity laser interactions with thin foil targets have been studied with a 100 TW laser system. Protons/ions with energies up to 10 MeV are accelerated either from the front or the rear surface of the target material. We have observed for the first time a self-radiograph of the target with a glass stalk holding the target itself in the stacked radiochromic films (RCF) placed behind the target. The self-radiography indicates that the fast ions accelerated backward, in a direction opposite to the laser propagation, are turning around in strong magnetic fields. This unique result is a signature of long-living (ns time scale) magnetic fields in the expanding plasma, which are important in energy transport during the intense laser irradiation and have never been considered in the previous studies. The magnetic fields induced by the main pulse near the absorption point expand rapidly with the backward accelerated protons in the pre-formed plasma. The protons are rotated by these magnetic fields and they are recorded in the RCF, making the self-radiography. Angular profiles of protons and multicharged ions accelerated from the target rear surface have been studied with the subpicosecond laser pulse produced by the 100 TW laser system. The protons/ions beam features recorded on CR39 show the hollow beam structure at the center of the beam pattern. This hollow structure in the proton/ion beam pattern associates to the electron transport inside the solid target, which affects the target's rear-surface emission or the electrostatic profile on the target rear-surface. The proton/ion beam filamentation has been seen clearly outside the hollow beam pattern in the CR39 images processed by the new digital imaging technique.

Paudel, Yadab Kumar

346

Proton Range Uncertainty Due to Bone Cement Injected Into the Vertebra in Radiation Therapy Planning  

SciTech Connect

We wanted to evaluate the influence of bone cement on the proton range and to derive a conversion factor predicting the range shift by correcting distorted computed tomography (CT) data as a reference to determine whether the correction is needed. Two CT datasets were obtained with and without a bone cement disk placed in a water phantom. Treatment planning was performed on a set of uncorrected CT images with the bone cement disk, and the verification plan was applied to the same set of CT images with an effective CT number for the bone cement disk. The effective CT number was determined by measuring the actual proton range with the bone cement disk. The effects of CT number, thicknesses, and position of bone cement on the proton range were evaluated in the treatment planning system (TPS) to draw a conversion factor predicting the range shift by correcting the CT number of bone cement. The effective CT number of bone cement was 260 Hounsfield units (HU). The calculated proton range for native CT data was significantly shorter than the measured proton range. However, the calculated range for the corrected CT data with the effective CT number coincided exactly with the measured range. The conversion factor was 209.6 [HU . cm/mm] for bone cement and predicted the range shift by approximately correcting the CT number. We found that the heterogeneity of bone cement could cause incorrect proton ranges in treatment plans using CT images. With an effective CT number of bone cement derived from the proton range and relative stopping power, a more actual proton range could be calculated in the TPS. The conversion factor could predict the necessity for CT data correction with sufficient accuracy.

Lim, Young Kyung [Department of Radiation Oncology, Institute of Health Sciences, Gyeongsang National University, Jinju (Korea, Republic of); Hwang, Ui-Jung [Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi (Korea, Republic of); Shin, Dongho, E-mail: dongho@ncc.re.kr [Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi (Korea, Republic of); Kim, Dong Wook [Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi (Korea, Republic of); Kwak, Jungwon [Department of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of); Yoon, Myonggeun; Lee, Doo Hyun; Lee, Se Byeong; Lee, Sang-Yeob [Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi (Korea, Republic of); Park, Sung Yong [Department of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of); Pyo, Hong Ryeol [Department of Radiation Oncology, Institute of Health Sciences, Gyeongsang National University, Jinju (Korea, Republic of); Proton Therapy Center, National Cancer Center, Goyang, Gyeonggi (Korea, Republic of); Department of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of); Department of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of)

2011-10-01

347

Field match verification during combination proton, photon, and electron therapy for oligometastatic inflammatory breast cancer  

SciTech Connect

Postmastectomy radiation therapy (PMRT) has been shown in randomized trials to improve overall survival for patients with locally advanced breast cancer. The standard PMRT clinical target volume (CTV) encompasses the chest wall and undissected regional lymphatics. Conformal isodose distributions covering the standard CTV with acceptable dose limits to normal tissue can typically be achieved with a combination of photon and electron fields. Field borders are marked on the patient's skin using a light field projection of each beam and are subsequently used to verify daily field matching clinically. Initial imaging of a patient with oligometastatic inflammatory breast cancer demonstrated direct extension of disease from the involved internal mammary lymph node chain into the anterior mediastinum as the only site of metastatic disease. The patient achieved a pathologic complete response to neoadjuvant chemotherapy and underwent mastectomy. The initial sites of gross disease, including the anterior mediastinal node was included in the CTV for PMRT, and treatment planning demonstrated a clear advantage to the inclusion of proton fields in this case. The absence of a light source on the proton delivery system that accurately projects proton field edges onto the patient's skin posed a significant challenge for daily verification of proton-to-photon and -electron field matching. Proton field-specific radiographic imaging devices were designed and used such that proton field edges could be delineated on the patient's skin and used for daily matching with photon and electron fields. Manufacture of the imaging devices was quick and inexpensive. Weekly verification of proton field alignment with the proton field delineation on the skin demonstrated agreement within 3-mm tolerance. The patient remains with no evidence of disease 18 months after completing radiation. Other patients with similar indications may benefit from multimodality radiation therapy.

Amos, Richard A., E-mail: richamos@mdanderson.org [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Woodward, Wendy A. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

2012-01-01

348

Possibility of proton motion through buckminsterfullerene  

NASA Astrophysics Data System (ADS)

The possibility of a proton entering a fullerene cage without breaking any C-C bond and undergoing oscillations through the cage is considered. A detailed understanding of the interaction of a proton with the five- and six-membered rings is obtained by examining proton-corannulene interaction, as a prototype.

Maheshwari, S.; Chakraborty, Debashis; Sathyamurthy, N.

1999-12-01

349

Operation of the TRIUMF Proton Therapy Facility  

Microsoft Academic Search

The Proton Therapy Facility at TRIUMF is now in routine operation treating ocular tumours using 70 MeV protons extracted from the 500 MeV H- cyclotron. This paper describes the proton beam line, treatment control and dosimetry systems which are designed to provide accurate treatment dose delivery. The reproducibility of the shape and range of the unmodulated Bragg peak for various

E. W. Blackmore; B. Evans; M. Mouat; C. Duzenli; R. Ma; T. Pickles; K. Paton

1997-01-01

350

Nonplanarity and the protonation behavior of porphyrins  

SciTech Connect

{sup 1}H NMR studies of the protonation of highly nonplanar porphyrins with strong acids reveal the presence of the previously elusive monocation, and show that its stability can be related to the amount of saddle distortion induced by protonation; the amount of saddle distortion for a porphyrin dication is also found to correlate well with the rate of intermolecular proton transfer.

SOMMA,MARIA S.; MEDFORTH,CRAIG J.; TH,KEVIN M.; SHELNUTT,JOHN A.

2000-03-21

351

Investigation of dose perturbations and radiographic visibility of potential fiducials for proton radiation therapy of the prostate  

PubMed Central

Image guidance using implanted fiducial markers is commonly used to ensure accurate and reproducible target positioning in radiation therapy for prostate cancer. The ideal fiducial marker is clearly visible in kV imaging, does not perturb the therapeutic dose in the target volume, and does not cause any artifacts on the CT images used for treatment planning. As yet, ideal markers that fully meet all three of these criteria have not been reported. In this study, twelve fiducial markers were evaluated for their potential clinical utility in proton radiation therapy for prostate cancer. In order to identify the good candidates, each fiducial was imaged using a CT scanner as well as a kV imaging system. Additionally, the dose perturbation caused by each fiducial was quantified using radiochromic film and a clinical proton beam. Based on the results, three fiducials were identified as good candidates for use in proton radiotherapy of prostate cancer.

Huang, Jessie Y.; Newhauser, Wayne D.; Zhu, X. Ronald; Lee, Andrew K.; Kudchadker, Rajat J.

2011-01-01

352

Proton Aurora and Trapped Particle Substorm Dynamics Compared  

NASA Astrophysics Data System (ADS)

Global auroral imaging data have shown us that auroral substorms are highly dynamic, complex and structured events. Since they are the result of processes taking place along extended magnetic field lines, auroral displays have been called the "TV screen" for the magnetoshpere. With recent IMAGE energetic neutral atom (ENA) observations we can globally correlate the dynamics of precipitating proton auroral phenomena with the dynamics of non-precipitating ENA substorm phenomena, tying processes in different regions along magnetic field lines together. We present comparisons for FUV proton aurora and MENA medium energy ENA observations of isolated substorm events during the summer of 2001. Both techniques show expected increases of particle fluxes during the expansion phase. The proton auroral response is typically quicker and initially stronger, with significant flux increases over short periods of time. The ENA response is more gradual, but enhanced flux levels will also persist up to several hours, much longer than the by comparison short-lived auroral displays. While this represents a considerable difference, the local time extent of auroral and ENA particles tracks much more closely. We will focus on this latter aspect of comparing the geophysical "topography" of trapped and precipitating particles.

Jahn, J.; Henderson, M. G.; Immel, T. J.; Mende, S. B.; Pollock, C. J.; Reeves, G. D.; Skoug, R.; Thomsen, M. F.

2002-05-01

353

Electron and Proton Wide-Angle Spectrometer (EPAS) on the CRRES spacecraft  

NASA Astrophysics Data System (ADS)

The electron and proton wide-angle spectrometer (EPAS) in the CRRES scientific payload utilizes arrays of solid-state detectors coupled with a magnetic deflection system in order to detect electrons (21-285 keV) and protons (37-3200 keV). The image size of the particles and the angular resolutions are controlled by the width of the entrance hole, the geometry of the pole pieces, and the position of the particles in the image plane. Additional features of the EPAS are described in some detail. Selected in-flight data are shown as an illustration of the instrument performance in the operational orbit.

Korth, A.; Kremser, G.; Wilken, B.; Guettler, W.; Ullaland, S. L.; Koga, R.

1994-03-01

354

Effects of relativity in proton-proton bremsstrahlung  

NASA Astrophysics Data System (ADS)

We investigate the influence of negative-energy states in proton-proton bremsstrahlung in a fully relativistic framework using the T matrix of Fleischer and Tjon. The contribution from negative-energy states in the single-scattering diagrams is shown to be large, indicating that relativistic effects are important. The rescattering contribution compensates some of the effect, which is shown to be a consequence of a low-energy theorem. The net effect of negative-energy states nevertheless is of the order of 20% at higher energies. We investigate retardation effects in the nucleon-nucleon (NN) interaction by means of a one-pion exchange model, which gives effects of the order of 15% at the pion-production threshold. We furthermore modify the NN T matrix to incorporate some of these effects, and find that on the level of single-scattering contributions they are of the order of 10%. We show predictions at incoming proton energy Tlab=190 MeV, where high accuracy measurements are being done at KVI, and conclude that even at these relatively low energies off-shell effects in the NN interaction and contributions from negative-energy states clearly show up.

Martinus, G. H.; Scholten, O.; Tjon, J. A.

1997-12-01

355

Effects of relativity in proton-proton bremsstrahlung  

SciTech Connect

We investigate the influence of negative-energy states in proton-proton bremsstrahlung in a fully relativistic framework using the T matrix of Fleischer and Tjon. The contribution from negative-energy states in the single-scattering diagrams is shown to be large, indicating that relativistic effects are important. The rescattering contribution compensates some of the effect, which is shown to be a consequence of a low-energy theorem. The net effect of negative-energy states nevertheless is of the order of 20{percent} at higher energies. We investigate retardation effects in the nucleon-nucleon (NN) interaction by means of a one-pion exchange model, which gives effects of the order of 15{percent} at the pion-production threshold. We furthermore modify the NN T matrix to incorporate some of these effects, and find that on the level of single-scattering contributions they are of the order of 10{percent}. We show predictions at incoming proton energy T{sub lab}=190MeV, where high accuracy measurements are being done at KVI, and conclude that even at these relatively low energies off-shell effects in the NN interaction and contributions from negative-energy states clearly show up. {copyright} {ital 1997} {ital The American Physical Society}

Martinus, G.H.; Scholten, O. [Kernfysisch Versneller Instituut, 9747 AA Groningen (the Netherlands)] [Kernfysisch Versneller Instituut, 9747 AA Groningen (the Netherlands); Tjon, J.A. [Institute for Theoretical Physics, University of Utrecht, 3508 TA Utrecht (the Netherlands)] [Institute for Theoretical Physics, University of Utrecht, 3508 TA Utrecht (the Netherlands)

1997-12-01

356

Compact proton spectrometers for measurements of shock  

SciTech Connect

The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

Mackinnon, A; Zylstra, A; Frenje, J A; Seguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M G; Casey, D T; Sinenian, N; Manuel, M; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G; Dewald, E; Doeppner, T; Edwards, M J; Glenzer, S H; Hicks, D; Landen, O L; London, R; Meezan, N B

2012-05-02

357

Microscopic dynamics of a base protonation  

NASA Astrophysics Data System (ADS)

The protonation of the base peroxynitrite in aqueous solution is investigated by way of the Car-Parrinello molecular dynamics technique. It is found that the protonation proceeds through an increase in the vibration amplitude of the hydrogen bond between the base and the hydronium ion. When the amplitude gets sufficiently large a proton may oscillate a few times between the base and the hydronium ion before it remains as part of peroxynitrous acid. The start of the protonation requires a certain orientation of the hydrogen bond. The estimated protonation time agrees well with the one obtained from femtosecond UV experiments.

Knudsgaard, Bjørn; Petersen, Christian; Thøgersen, Jan; Keiding, Søren Rud; Jensen, Svend J. Knak

2008-10-01

358

Surface-coupled proton exchange of a membrane-bound proton acceptor  

PubMed Central

Proton-transfer reactions across and at the surface of biological membranes are central for maintaining the transmembrane proton electrochemical gradients involved in cellular energy conversion. In this study, fluorescence correlation spectroscopy was used to measure the local protonation and deprotonation rates of single pH-sensitive fluorophores conjugated to liposome membranes, and the dependence of these rates on lipid composition and ion concentration. Measurements of proton exchange rates over a wide proton concentration range, using two different pH-sensitive fluorophores with different pKas, revealed two distinct proton exchange regimes. At high pH (> 8), proton association increases rapidly with increasing proton concentrations, presumably because the whole membrane acts as a proton-collecting antenna for the fluorophore. In contrast, at low pH (< 7), the increase in the proton association rate is slower and comparable to that of direct protonation of the fluorophore from the bulk solution. In the latter case, the proton exchange rates of the two fluorophores are indistinguishable, indicating that their protonation rates are determined by the local membrane environment. Measurements on membranes of different surface charge and at different ion concentrations made it possible to determine surface potentials, as well as the distance between the surface and the fluorophore. The results from this study define the conditions under which biological membranes can act as proton-collecting antennae and provide fundamental information on the relation between the membrane surface charge density and the local proton exchange kinetics.

Sanden, Tor; Salomonsson, Lina; Brzezinski, Peter; Widengren, Jerker

2010-01-01

359

Proton solvation and transport in hydrated nafion.  

PubMed

Proton solvation properties and transport mechanisms have been studied in hydrated Nafion using the self-consistent multistate empirical valence bond (SCI-MS-EVB) method that includes the effects excess proton charge defect delocalization and Grotthuss proton hopping. It was found that sulfonate groups influence excess proton solvation, as well as the proton hydration structure, by stabilizing a more Zundel-like (H(5)O(2)(+)) structure in their first solvation shells. Hydrate proton-related hydrogen bond networks were observed to be more stable than networks with water alone. Diffusion rates, Arrhenius activation energies, and transport pathways were calculated and analyzed to characterize the nature of the proton transport. Diffusion rate analysis suggests that a proton-hopping mechanism dominates the proton transport for the studied water loading levels and that there is a clear degree of anticorrelation with the vehicular transport. The activation energy drops quickly with an increasing water content when the water loading level is smaller than ?10 H(2)O/SO(3)(-), which is consistent with experimental observations. The sulfonate groups were also found to affect the proton hopping directions. The temperature and water content effects on the proton transport pathways were also investigated. PMID:21510678

Feng, Shulu; Voth, Gregory A

2011-05-19

360

Proton Aurora Dynamics in Response to the IMF and Solar Wind Variations  

NASA Technical Reports Server (NTRS)

On May 23, 2000, proton auroras observed by IMAGE (Imager for Magnetopause to Aurora Global Exploration) FUV (Far Ultraviolet) on the dayside were very dynamic. Auroral pattern in the cusp is well correlated with Interplanetary Magnetic Field (IMF) and solar wind parameters. When IMF were northward, cusp proton aurora appeared at high latitude poleward from the auroral oval. A high-latitude proton aurora brightened after solar wind ion temperature increased and it disappeared after IMF turned southward. Under the southward IMF condition, auroral activity occurred only in the dayside auroral oval. As IMF $B_z$ reverted to northward, cusp proton aurora reappeared at high latitude. The magnetic local time of the cusp proton aurora changes with the IMF $B_y$ polarity, consistent with previous reports. These results suggest an upstream source of the high-latitude cusp proton aurora for this event. One possible explanation is that bow shock energetic ions are transported into the cusp via the high-latitude magnetic merging process to induce optical emissions in the ionosphere.

Chang, S.; Mende, S.; Frey, H.; Gallagher, D. L.; Lepping, R. P.; Six, N. Frank (Technical Monitor)

2002-01-01

361

Proton probing of plasmas and shocked materials  

NASA Astrophysics Data System (ADS)

Laser driven proton beams have recently been used to diagnose transient fields in laser produced plasmas. A recent development of proton probing is the application of deflectometry techniques to obtain precise measurements of proton beam deflections and to measure the size and location of the proton source on a single shot. Proton deflectometry has been used to measure small angular deflections of the proton beam caused by electromagnetic fields in plasmas produced by the LULI laser at Ecolé Polytechnique. Proton probing has great potential for probing shocked and heated materials in conditions that are opaque to conventional optical and soft x-ray techniques. These developments will be described. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.

MacKinnon, A. J.; Patel, P. K.; Hicks, D.; Price, D.; Town, R. P.; Hatchett, S.; Lasinski, B.; Langdon, B.; Key, M. H.; Borghesi, M.; Romagnani, L.; Pretzler, G.; Toncian, T.; Willi, O.; King, J.; Snavely, R.; Freeman, R.; Koenig, M.; Martinolli, E.; Lepape, S.; Benuzzi-Mounaix, A.; Audebert, P.; Gauthier, J. C.; Boehly, T.

2003-10-01

362

ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.  

SciTech Connect

The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.

BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; BLASKIEWICZ, M.; BRAVAR, A.; BRENNAN, J.M.; BRUNO, D.; BUNCE, G.; ET AL.

2006-10-02

363

Dynamic Protonation Equilibrium of Solvated Acetic Acid  

SciTech Connect

For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.

Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.

2007-04-13

364

How long solar proton radiation belts exists?  

NASA Astrophysics Data System (ADS)

Solar protons of 1-5 MeV range were trapped during recovery phases of the strong magnetic storms on October 2003, July and November 2004 and after additional acceleration remain in the proton radiation belts for a long time. Using measurements of the low-altitude polar satel-lites CORONAS-F, SERVIS-1 and TATJANA-UNIVERSITETSKY we found, that enhanced proton flux of the 15 MeV energy remains about half a year at L=3-5, and about one year protons with 1 MeV energy. Additional 1 MeV proton belt at L=1.8-2.2 existed continuously from October 2003 at least to December 2006. Extrapolation of the measurements to the pre-vious 11-year cycles shows that solar proton contribution to the proton radiation belt of 1-5 MeV energy range may be important for the half of the solar cycle time.

Lazutin, Leonid; Logachev, Yurii; Muravjeva, E.

365

Increased efficacy of radiation therapy by use of proton beam.  

PubMed

Proton beam treatment techniques provide a powerful approach to improving dose distribution (decrease treatment volume towards target volume) and hence increasing dose to target with resultant higher tumor control rates and lesser morbity. To achieve these dose distributions in patients requires use of modern imaging techniques, rigid immobilization systems, confirmation of target position vis a vis the proton beam at each treatment session, treatment planning which feature beam's eye view, displays of uncertainty, dose at each anatomic point, boli based on accurate assessment of density along each pixel, etc. Experience at MGH/MEEI/HCL has yielded a disease-free survival of 78% for patients with chordoma/chondrosarcoma of base of skull. Local control is achieved by 98% of patients treated for choroidal melanoma. PMID:2154047

Suit, H D; Goitein, M; Munzenrider, J; Verhey, L; Urie, M; Gragoudas, E; Koehler, A; Gottschalk, B; Sisterson, J; Tatsuzaki, H

1990-01-01

366

Test of an amorphous silicon detector in medical proton beams  

NASA Astrophysics Data System (ADS)

Ion beam radiation therapy for cancer treatment allows for improved dose confinement to the target in comparison with the standard radiation therapy using high energy photons. Dose delivery to the patient using focused ion beam scanning over the target volume is going to be increasingly used in the upcoming years. The high precision of the dose delivery achieved in this way has to be met by practical methods for beam monitoring with sufficient spatial resolution in two dimensions. Flat panel detectors, used for photon portal imaging at the newest medical linear accelerators, are an interesting candidate for this purpose. Initial detector tests presented here were performed using proton beams with the highest available energy. The investigations include measurements of beam profiles at different beam intensities and for different beam width, as well as the signal linearity. Radiation damage was also investigated. The obtained results show that the detector is a promising candidate to be used in the therapeutic proton beams.

Martišíková, M.; Hesse, B. M.; Nairz, O.; Jäkel, O.

2011-05-01

367

Proton-nuclear magnetic resonance relaxation times in brain edema  

SciTech Connect

Proton relaxation times of protein solutions, bovine brain, and edematous feline brain tissue were studied as a function of water concentration, protein concentration, and temperature. In accordance with the fast proton exchange model for relaxation, a linear relation could be established between R1 and the inverse of the weight fraction of tissue water. This relation also applied to R2 of gray matter and of protein solutions. No straightforward relation with water content was found for R2 of white matter. Temperature-dependent studies indicated that in this case, the slow exchange model for relaxation had to be applied. The effect of macromolecules in physiological relevant concentrations on the total relaxation behavior of edematous tissue was weak. Total water content changes predominantly affected the relaxation rates. The linear relation may have high clinical potential for assessment of the status of cerebral edema on the basis of T1 and T2 readings from MR images.

Kamman, R.L.; Go, K.G.; Berendsen, H.J. (Univ. of Groningen (Netherland))

1990-01-01

368

Direct Observation of Two Proton Radioactivity Using Digital Photography  

SciTech Connect

Recently the observation of a new type of spontaneous radioactive decay has been claimed in which two protons are simultaneously ejected by an atomic nucleus from the ground state1,2,3. Experimental data obtained for the extremely neutron-deficient nuclei 45Fe and 54Zn, were interpreted as the first evidence of such a decay mode which has been sought since 1960.4 However, the technique applied in those studies allowed only measurements of the decay time and the total energy released. Particles emitted in the decay were not identified and the conclusions had to be supported by theoretical arguments. Here we show for the first time, directly and unambiguously, that 45Fe indeed disintegrates by two-proton decay. Furthermore, we demonstrate that the decay branch of this isotope leads to various particle emission channels including two-proton and three-proton emission. To achieve this result we have developed a new type of detector V the Optical Time Projection Chamber (OTPC) in which digital photography is applied to nuclear physics for the first time. The detector records images of tracks from charged particles, allowing for their unambiguous identification and the reconstruction of decay events in three dimensions. This new and simple technique provides a powerful method to identify exotic decay channels involving emission of charged particles. It is expected that further studies with the OTPC device will yield important information on nuclei located at and beyond the proton drip-line, thus providing new material for testing and improving models of very unstable atomic nuclei.

Rykaczewski, Krzysztof Piotr [ORNL; Pfutzner, M. [IEP, Warsaw University; Dominik, Wojciech [Warsaw University; Janas, Z. [IEP, Warsaw University; Miernik, K. [IEP, University of Warsaw; Bingham, C. R. [University of Tennessee, Knoxville (UTK); Czyrkowski, Henryk [Warsaw University; Cwiok, Mikolaj [Warsaw University; Darby, Iain [University of Tennessee, Knoxville (UTK); Dabrowski, Ryszard [Warsaw University; Ginter, T. N. [NSCL Michigan State University; Grzywacz, Robert Kazimierz [ORNL; Karny, M. [IEP, Warsaw University; Korgul, A. [IEP, Warsaw University; Kusmierz, Waldemar [Warsaw University; Liddick, Sean [University of Tennessee, Knoxville (UTK); Rajabali, Mustafa [University of Tennessee, Knoxville (UTK); Stolz, A. [NSCL Michigan State University

2007-01-01

369

Proton radiation therapy for head and neck cancer: a review of the clinical experience to date.  

PubMed

Proton beam radiation has been used for cancer treatment since the 1950s, but recent increasing interest in this form of therapy and the construction of hospital-based and clinic-based facilities for its delivery have greatly increased both the number of patients and the variety of tumors being treated with proton therapy. The mass of proton particles and their unique physical properties (ie, the Bragg peak) allow proton therapy to spare normal tissues distal to the tumor target from incidental irradiation. Initial observations show that proton therapy is particularly useful for treating tumors in challenging locations close to nontarget critical structures. Specifically, improvements in local control outcomes for patients with chordoma, chonodrosarcoma, and tumors in the sinonasal regions have been reported in series using proton. Improved local control and survival outcomes for patients with cancer of the head and neck region have also been seen with the advent of improvements in better imaging and multimodality therapy comprising surgery, radiation therapy, and chemotherapy. However, aggressive local therapy in the proximity of critical normal structures to tumors in the head and neck region may produce debilitating early and late toxic effects. Great interest has been expressed in evaluating whether proton therapy can improve outcomes, especially early and late toxicity, when used in the treatment of head and neck malignancies. This review summarizes the progress made to date in addressing this question. PMID:24837890

Holliday, Emma B; Frank, Steven J

2014-06-01

370

Physiologic Reactions After Proton Beam Therapy in Patients With Prostate Cancer: Significance of Urinary Autoactivation  

SciTech Connect

Purpose: Proton therapy is a sophisticated treatment modality for prostate cancer. We investigated how physiologic factors affected the distribution of autoactivation as detected by positron emission tomography (PET) after proton beam therapy. Methods and Materials: Autoactivation was evaluated in 59 patients treated with a 210-MeV proton beam. Data acquisition for autoactivation by PET started 5minutes after proton irradiation to assess activation. In the first 29 patients, five regions of interest were evaluated: planning target volume (PTV) center, urinary bladder inside the PTV, urinary bladder outside the PTV, rectum (outside the PTV), and contralateral femoral bone head (outside the PTV). In the remaining 30 patients, urine activity was measured directly. In a phantom study autoactivation and its diffusion after proton beam irradiation were evaluated with water or an ice block. Results: Mean activities calculated by use of PET were 629.3Bq in the PTV center, 555.6Bq in the urinary bladder inside the PTV, 332.5Bq in the urinary bladder outside the PTV, 88.4Bq in the rectum, and 23.7Bq in the femoral bone head (p < 0.001). Mean urine activity was 679.4Bq, recorded 10minutes after therapy completion, and the half-life for urine autoactivation was 4.5minutes. Conclusions: Urine is a major diffusion mediator of autoactivation after proton beam therapy. Our results indicate that physiologic factors can influence PET images of autoactivation in the context of proton beam therapy verification.

Shimizu, Masakazu [Department of Radiation Technology, Hyogo Ion Beam Medical Center, Tatsuno (Japan); Sasaki, Ryohei [Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe (Japan)], E-mail: rsasaki@med.kobe-u.ac.jp; Miyawaki, Daisuke [Department of Radiology, Hyogo Ion Beam Medical Center, Tatsuno (Japan); Nishimura, Hideki [Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe (Japan); Demizu, Yusuke [Department of Radiology, Hyogo Ion Beam Medical Center, Tatsuno (Japan); Akagi, Takashi [Department of Accelerator Managing, Hyogo Ion Beam Medical Center, Tatsuno (Japan); Suga, Daisaku [Department of Radiation Technology, Hyogo Ion Beam Medical Center, Tatsuno (Japan); Sakamoto, Hidenobu [Mitsubishi Electric, Kobe (Japan); Murakami, Masao [Department of Radiology, Hyogo Ion Beam Medical Center, Tatsuno (Japan); Sugimura, Kazuro [Division of Radiation Oncology, Kobe University Graduate School of Medicine, Kobe (Japan); Hishikawa, Yoshio [Department of Radiology, Hyogo Ion Beam Medical Center, Tatsuno (Japan)

2009-10-01

371

The alternating gradient proton synchrotron  

Microsoft Academic Search

This completes an introduction to the new A.G. proton synchrotron showing how the idea started, the original optimism and\\u000a the subsequent disenchantment as the development work proceeded. We are left with a new type of machine that offers a method\\u000a of getting very high energy particles cheaper than by any other artificial means but at the expense of imposing very

John Bertram Adams

1955-01-01

372

Protons in near earth orbit  

Microsoft Academic Search

The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux

J. Alcaraz; D. Alvisi; B. Alpat; G. Ambrosi; H. Anderhub; L. Ao; A. Arefiev; P. Azzarello; E. Babucci; L. Baldini; M. Basile; D. Barancourt; F. Barao; G. Barbier; G. Barreira; R. Battiston; R. Becker; U. Becker; L. Bellagamba; P. Béné; J. Berdugo; P. Berges; B. Bertucci; A. Biland; S. Bizzaglia; S. Blasko; G. Boella; M. Boschini; Maurice Bourquin; G. Bruni; M. Buenerd; J. D. Burger; W. J. Burger; X. D. Cai; R. Cavalletti; C. Camps; P. Cannarsa; M. Capell; D. Casadei; J. Casaus; G. Castellini; Y. H. Chang; H. F. Chen; H. S. Chen; Z. G. Chen; N. A. Chernoplekov; A. Chiarini; Tzi Hong Chiueh; Y. L. Chuang; F. Cindolo; V. Commichau; A. Contin; P. Crespo; M. Cristinziani; J. P. da Cunha; T. S. Dai; J. D. Deus; N. Dinu; L. Djambazov; I. D'Antone; Z. R. Dong; P. Emonet; J. Engelberg; F. J. Eppling; T. Eronen; G. Esposito; Pierre Extermann; Jean Favier; C. C. Feng; E. Fiandrini; F. Finelli; P. H. Fisher; R. Flaminio; G. Fluegge; N. Fouque; Yu. Galaktionov; M. Gervasi; P. Giusti; D. Grandi; W. Q. Gu; K. Hangarter; A. Hasan; V. Hermel; H. Hofer; M. A. Huang; W. Hungerford; M. Ionica; R. Ionica; M. Jongmanns; K. Karlamaa; W. Karpinski; G. Kenney; J. Kenny; W. Kim; A. Klimentov; R. Kossakowski; V F Koutsenko; G. Laborie; T. Laitinen; G. Lamanna; G. Laurenti; A. Lebedev; S. C. Lee; G. Levi; P. Levtchenko; C. L. Liu; H. T. Liu; M. Lolli; I. Lopes; G. Lu; Y. S. Lu; K. Lübelsmeyer; D. Luckey; W. Lustermann; C. Maña; A. Margotti; F. Massera; F. Mayet; R. R. McNeil; B. Meillon; M. Menichelli; F. Mezzanotte; R. Mezzenga; A. Mihul; G. Molinari; A M Mourão; A. Mujunen; F. Palmonari; G. Pancaldi; A. Papi; I. H. Park; M. Pauluzzi; Felicitas Pauss; E. Perrin; A. Pesci; A. Pevsner; R. Pilastrini; M. Pimenta; V. Plyaskin; V Pozhidaev; H. Postema; V. Postolache; E. Prati; N. Produit; P. G. Rancoita; D. Rapin; F. Raupach; S. Recupero; D. Ren; Z. Ren; M. Ribordy; J. P. Richeux; E. Riihonen; J. Ritakari; U. Roeser; C. Roissin; R. Sagdeev; D. Santos; G. Sartorelli; A. Schultz von Dratzig; G. Schwering; E. S. Seo; V. Shoutko; E. Shoumilov; R. Siedling; D. Son; T. Song; M. Steuer; G. S. Sun; H. Suter; X. W. Tang; Samuel C. C. Ting; S. M. Ting; M. Tornikoski; G. Torromeo; J. Torsti; J E Trümper; J. Ulbricht; S. Urpo; I. Usoskin; E. Valtonen; J. Vandenhirtz; F. Velcea; E P Velikhov; B. Verlaat; I Vetlitskii; F. Vezzu; J. P. Vialle; Gert M Viertel; D. Vité; H P Von Gunten; S. Waldmeier Wicki; W. Wallraff; B. C. Wang; J. Z. Wang; Y. H. Wang; K. Wiik; C. Williams; S. X. Wu; P. C. Xia; J. L. Yan; L. G. Yan; C. G. Yang; M. Yang; S. W. Ye; P. Yeh; Z. Z. Xu; H. Y. Zhang; Z. P. Zhang; D. X. Zhao; G. Y. Zhu; W. Z. Zhu; H. L. Zhuang; A. Zichichi

2000-01-01

373

Solid-state proton conductors  

SciTech Connect

The purpose of this program was to survey the field of solid-state proton conductors (SSPC), identify conductors that could be used to develop solid-state fuel cells suitable for use with coal derived fuel gases, and begin the experimental research required for the development of these fuel cells. This document covers the following topics: the history of developments and current status of the SSPC, including a review of proton conducting electrolyte structures, the current status of the medium temperature SSPC development, electrodes for moderate temperature (SSPC) fuel cell, basic material and measurement techniques applicable for SSPC development, modeling and optimization studies. Correlation and optimization studies, to include correlation studies on proton conduction and oxide cathode optimization for the SSPC fuel cell. Experiments with the SSPC fuel cells including the fabrication of the electrolyte disks, apparatus for conducting measurements, the strontium-cerium based electrolyte, the barium-cerium based electrolyte with solid foil electrodes, the barium-cerium based electrolyte with porous electrodes, and conduction mechanisms. 164 refs., 27 figs., 13 tabs.

Jewulski, J.R.; Osif, T.L.; Remick, R.J.

1990-12-01

374

The photosynthetic water oxidase: its proton pumping activity is short-circuited within the protein by DCCD  

PubMed Central

The photosynthetic water oxidase is composed of ˜15 polypeptides which are grouped around two functional parts: photosystem II and the catalytic manganese centre. Photochemically driven vectorial electron transfer between the manganese centre and bound plastoquinone causes deprotonation–protonation reactions at opposite sides of the thylakoid membrane. Thereby the water oxidase acts as a proton pump. Incubation of stacked thylakoids with N,N'-dicyclohexylcarbodiimide (DCCD) short-circuited its proton pumping activity. Under flashing light, the extent of both proton release into the lumen by water oxidation and of proton uptake from the medium by reduced quinone was diminished. Instead there was a rapid electrogenic backreaction with a strong H/D-isotope effect. Apparently protons which were produced by water oxidation were channelled across the transmembrane protein to the bound quinone. A more rapid protonation of the reduced quinone was evident from a shortening of the time lag for the reduction of photosystem I. These effects were paralleled by the preferential labelling with [14C]DCCD in stacked thylakoids of two polypeptides with 20 and 24 kd apparent molecular mass. These may be capping the oxidizing and the reducing terminus of the water oxidase to control proton extrusion and proton uptake respectively. Images

Jahns, Peter; Polle, Andrea; Junge, Wolfgang

1988-01-01

375

Correlated electron and proton transport in cytochrome c oxidase: Coulomb proton pump with kinetic gating  

NASA Astrophysics Data System (ADS)

I will discuss correlated transport of electrons and protons in cytochrome c oxidase, the terminal enzyme in the respiratory electron transport chain of aerobic organisms. This enzyme catalyzes the reduction of atmospheric oxygen to water in our cells, and utilizes the free energy of oxygen reduction for the creation the membrane proton gradient by pumping protons across the membrane. The proton gradient subsequently drives the synthesis of ATP. The details of the mechanism of this redox-driven proton pump are unknown. Computer simulations and theoretical modeling point to a possible mechanism of this biological molecular machine in which electron transport is coupled to proton translocation.

Stuchebrukhov, Alexei

2008-03-01

376

Characterizing proton relaxation times for metallic and magnetic layer-by-layer-coated, DNA-templated nanoparticle chains.  

PubMed

Metallic and superparamagnetic DNA-templated nanoparticle (NP) chains are examined as potential imaging agents. Proton relaxation times (T(1) and T(2)) are measured for DNA nanostructures using nuclear magnetic resonance (NMR) spectroscopy. The layer-by-layer (LBL) method was used to encapsulate the DNA-templated NP chains and demonstrated a change in proton relaxation times. Results from this study suggest that LBL-coated, DNA-templated nanostructures can serve as effective imaging agents for magnetic resonance imaging (MRI) applications. PMID:20484793

Jaganathan, Hamsa; Gieseck, Richard L; Ivanisevic, Albena

2010-06-18

377

Neutron Imaging Camera  

NASA Technical Reports Server (NTRS)

The Neutron Imaging Camera (NIC) is based on the Three-dimensional Track Imager (3DTI) technology developed at GSFC for gamma-ray astrophysics applications. The 3-DTI, a large volume time-projection chamber, provides accurate, approximately 0.4 mm resolution, 3-D tracking of charged particles. The incident direction of fast neutrons, En > 0.5 MeV, are reconstructed from the momenta and energies of the proton and triton fragments resulting from (sup 3)He(n,p) (sup 3)H interactions in the 3-DTI volume. The performance of the NIC from laboratory and accelerator tests is presented.

Hunter, Stanley; deNolfo, G. A.; Barbier, L. M.; Link, J. T.; Son, S.; Floyd, S. R.; Guardala, N.; Skopec, M.; Stark, B.

2008-01-01

378

Neutron imaging camera  

NASA Astrophysics Data System (ADS)

The Neutron Imaging Camera (NIC) is based on the Three-dimensional Track Imager (3_DTI) technology developed at GSFC for gamma-ray astrophysics applications. The 3-DTI, a large volume time-projection chamber, provides accurate, ~0.4 mm resolution, 3-D tracking of charged particles. The incident direction of fast neutrons, En > 0.5 MeV, are reconstructed from the momenta and energies of the proton and triton fragments resulting from 3He(n,p)3H interactions in the 3-DTI volume. The performance of the NIC from laboratory is presented.

Hunter, S. D.; de Nolfo, G. A.; Barbier, L. M.; Link, J. T.; Son, S.; Floyd, S. R.; Guardala, N.; Skopec, M.; Stark, B.

2008-05-01

379

Proton-decoupled 19F spectroscopy of 5-FU catabolites in human liver.  

PubMed

An RF network and a dual-tuned surface coil are described for obtaining proton-decoupled, NOE enhanced 19F spectra from a whole body clinical imager operating at 1.5 Tesia. The network removes 19F frequency noise from the decoupler transmitter, and prevents preamplifier saturation from high-level decoupling signals. Proton decoupling of 19F spectra was optimized using a sample of urine containing 5-fluorouracil (5-FU) and its catabolite fluoro-beta-alanine (FBAL). Proton-decoupled 19F spectroscopy in vivo is demonstrated by obtaining both nonlocalized spectra and spectra localized with three-dimensional chemical shift imaging from the liver of patients undergoing 5-FU chemotherapy. PMID:9055218

Murphy-Boesch, J; Li, C W; He, L; Padavic-Shaller, K A; Negendank, W; Brown, T R

1997-03-01

380

Scanning proton microprobe analysis of strontium in an arctic charr, Salvelinus alpinus , otolith: implications for the interpretation of anadromy  

Microsoft Academic Search

Synopsis Scanning proton microprobe imaging has been used to map the distribution of strontium (Sr) in an arctic charr, Salvelinus alpinus, otolith. X-ray maps show that Sr variation follows an oscillatory zoned pattern which correlates with optically resolved zones (annuli). The internal region of the otolith shows optical zonation but no significant Sr content. Comparison of the optical image with

Norman M. Halden; John A. Babaluk; John L. Campbell; William J. Teesdale

1995-01-01

381

Mechanisms of proton pumping in bacteriorhodopsin  

SciTech Connect

The purple membrane of Halobacterium halobium probably represents the simplest biological solar energy conversion system. Light absorbed by bacteriorhodopsin directly leads to the transport of protons across the cell membrane. The resulting chemosmotic potential can be used to make ATP. An additional feature of the purple membrane is its ability to pump protons over a wide variety of salt concentration including in extreme saline environments. This project investigates the relationship between the transport of protons across the membrane and structure and conformation of bacteriorhodospin. We have proposed experiments to study the pH dependence of proton pumping. Secondly, we are examining the role of divalent cations and the effect of the large surface potential of the purple membrane on the proton pumping function of this membrane using the photocurrents associated with the pumping process. Finally we are studying the role of proteinatable amino acids in proton transport. 16 refs.

Ebrey, T.G.

1991-01-01

382

Two-pulse biexponential-weighted 23Na imaging.  

PubMed

A new method is proposed for acquiring 3D biexponential-weighted sodium images with two instead of three RF pulses to allow for shorter repetition time at high magnetic fields (B0?7 T) and reduced SAR. The second pulse converts single- into triple-quantum coherences in regions containing sodium ions which are restricted in mobility. Since only single-quantum coherences can be detected, an image acquired after the second pulse is intrinsically single-quantum-filtered and can be used to generate a biexponential-weighted sodium image by a weighted subtraction with the spin-density-weighted image acquired between the pulses. The proposed sequence generates biexponential-weighted sodium images of in vivo human brain with 140% higher SNR than triple-quantum-filtered sodium images and 4% higher SNR than a biexponential-weighted sequence with three RF pulses at equal acquisition time and with 1/3 lower SAR. As SAR is reduced, accordingly repetition time can be spared to obtain even higher SNR-time efficiency. In comparison to a difference image generated from two images of a double-readout sequence, the proposed two-pulse sequence yields about 14% higher SNR. Our new two-pulse biexponential-weighted sequence allows for acquisition of full 3D data sets of the human brain in vivo with a nominal resolution of (5 mm)(3) in about 10 min. PMID:24530955

Benkhedah, Nadia; Bachert, Peter; Nagel, Armin M

2014-03-01

383

A proton mass doublet from general relativity  

Microsoft Academic Search

Summary  This paper discusses the features of the proton mass according to the author's nonlinear, spinor field theory in general relativity.\\u000a Within its context, where mass doublets are generally predicted for all spinor matter fields, it is shown, in a semi-quantitative\\u000a fashion, that 1) in addition to the normal (stable) proton there is a heavier proton that has a mass of

M. Sachs

1980-01-01

384

Recent Development in Proton Spin Physics  

SciTech Connect

In the naive model of the proton, its 1/2 spin is carried by its quark constituents. However, experiments over the last several decades have shown that the quark spin only contribute a small portion of the proton spin. In this talk, I will present recent developments exploring this proton spin puzzle, and focus on the progress made in the last few years on the longitudinal spin physics, the generalized parton distribution physics, and the transverse spin physics.

Yuan, Feng

2008-12-10

385

Statistical analysis of SAMPEX PET proton measurements  

NASA Astrophysics Data System (ADS)

We present a statistical study of the distributions of proton counts from the Proton-Electron Telescope aboard the low-altitude polar satellite SAMPEX. Our statistical analysis shows that histograms of observed proton counts are generally distributed according to Poisson distributions but are sometimes quite different. The observed departures from Poisson distributions can be attributed to variations of the average flux or to the non-constancy of the detector lifetimes.

Pierrard, V.; Lemaire, J.; Heynderickx, D.; Kruglanski, M.; Looper, M.; Blake, B.; Mewaldt, D.

2000-07-01

386

Potential energy surfaces for protonation of hydrochlorofluoromethanes  

Microsoft Academic Search

The proton affinities (PAs) and potential energy surfaces (PESs) of hydrochlorofluoromethanes (HCFMs) have been predicted by using Gaussian-3X (G3X) method. The G3X PAs agree with previous G3 predictions, while the large discrepancies between theoretical and experimental PAs persisted for CH2F2, CHF3, and CF3Cl. Protonated HCFMs usually have multiple structures, and structures with protonations at F-atom, [Methyl-FH]+, are the most stable.

Yi-Liang He; Liming Wang

2009-01-01

387

A summary of major solar proton events  

Microsoft Academic Search

Solar proton events have been routinely detected by satellites since the 20th solar cycle; however, before that time only very major proton events were detected at the Earth. Even though the detection thresholds differed between the 19th and more recent cycles, more than 200 solar proton events with a flux of over 10 particles (cm2 s ster)-1 above 10 MeV

D. F. Smart

1990-01-01

388

Proton beam therapy control system  

DOEpatents

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

Baumann, Michael A; Beloussov, Alexandre V; Bakir, Julide; Armon, Deganit; Olsen, Howard B; Salem, Dana

2013-12-03

389

Proton beam therapy control system  

DOEpatents

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

Baumann, Michael A. (Riverside, CA) [Riverside, CA; Beloussov, Alexandre V. (Bernardino, CA) [Bernardino, CA; Bakir, Julide (Alta Loma, CA) [Alta Loma, CA; Armon, Deganit (Redlands, CA) [Redlands, CA; Olsen, Howard B. (Colton, CA) [Colton, CA; Salem, Dana (Riverside, CA) [Riverside, CA

2008-07-08

390

Proton decay studies at HRIBF  

SciTech Connect

A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {mu}sec. In this paper we present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu.

Batchelder, J. C. [Oak Ridge Associated Universities, Oak Ridge Tennessee 37831 (United States); Bingham, C. R. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); University of Tennessee, Knoxville, Tennessee 37996 (United States); Rykaczewski, K. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); IEP, Warsaw University, 00681 Warsaw, Hoza 69 (Poland); Toth, K. S.; Mas, J. F.; McConnell, J. W.; Yu, C.-H. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Davinson, T.; Slinger, R. C.; Woods, P. J. [University of Edinburgh, Edinburgh, EH9 3JZ (United Kingdom); Ginter, T. N. [Vanderbilt University, Nashville, Tennessee 37235 (United States); Gross, C. J. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831 (United States); Grzywacz, R.; Kim, S. H.; Weintraub, W. [University of Tennessee, Knoxville, Tennessee 37996 (United States); Janas, Z.; Karny, M. [IEP, Warsaw University, 00681 Warsaw, Hoza 69 (Poland); MacDonald, B. D. [Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Piechaczek, A.; Zganjar, E. F. [Louisiana State University, Baton Rouge, Louisiana 70803 (United States)] (and others)

1998-12-21

391

Proton decay studies at HRIBF  

SciTech Connect

A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {mu}sec. In this paper we present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu. {copyright} {ital 1998 American Institute of Physics.}

Batchelder, J.C. [Oak Ridge Associated Universities, Oak Ridge , Tennessee 37831 (United States); Bingham, C.R.; Rykaczewski, K.; Toth, K.S.; Mas, J.F.; McConnell, J.W.; Yu, C. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Bingham, C.R.; Grzywacz, R.; Kim, S.H.; Weintraub, W. [University of Tennessee, Knoxville, Tennessee 37996 (United States); Rykaczewski, K.; Janas, Z.; Karny, M. [IEP, Warsaw University, 00681 Warsaw, Hoza 69 (Poland); Davinson, T.; Slinger, R.C.; Woods, P.J. [University of Edinburgh, Edinburgh, EH9 3JZ (United Kingdom); Ginter, T.N. [Vanderbilt University, Nashville, Tennessee 37235 (United States); Gross, C.J. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831 (United States); MacDonald, B.D. [Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Piechaczek, A.; Zganjar, E.F. [Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Ressler, J.J.; Walters, W.B. [University of Maryland, College Park, Maryland 20742 (United States); Szerypo, J. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States)

1998-12-01

392

Proton beam therapy control system  

DOEpatents

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

Baumann, Michael A. (Riverside, CA); Beloussov, Alexandre V. (San Bernardino, CA); Bakir, Julide (Alta Loma, CA); Armon, Deganit (Longmeadow, MA); Olsen, Howard B. (Irvine, CA); Salem, Dana (Riverside, CA)

2010-09-21

393

Proton beam therapy control system  

DOEpatents

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

Baumann, Michael A; Beloussov, Alexandre V; Bakir, Julide; Armon, Deganit; Olsen, Howard B; Salem, Dana

2013-06-25

394

Multiparticle production in deep inelastic lepton scattering and soft proton proton collisions  

SciTech Connect

We demonstrate how the theoretical knowledge about multiparticle production in deep inelastic lepton scattering can be incorporated into a multistring model for low p/sub t/ proton proton collisions. 25 refs., 8 figs.

Werner, K.

1987-06-01

395

Active role of proton in excited state intramolecular proton transfer reaction.  

PubMed

Proton transfer is one of the most important elementary reactions in chemistry and biology. The role of proton in the course of proton transfer, whether it is active or passive, has been the subject of intense investigations. Here we demonstrate the active role of proton in the excited state intramolecular proton transfer (ESIPT) of 10-hydroxybenzo[h]quinoline (HBQ). The ESIPT of HBQ proceeds in 12 ± 6 fs, and the rate is slowed down to 25 ± 5 fs for DBQ where the reactive hydrogen is replaced by deuterium. The results are consistent with the ballistic proton wave packet transfer within the experimental uncertainty. This ultrafast proton transfer leads to the coherent excitation of the vibrational modes of the product state. In contrast, ESIPT of 2-(2'-hydroxyphenyl)benzothiazole (HBT) is much slower at 62 fs and shows no isotope dependence implying complete passive role of the proton. PMID:23374075

Lee, Junghwa; Kim, Chul Hoon; Joo, Taiha

2013-02-21

396

Proton angular distribution research by a new angle-resolved proton energy spectrometer  

NASA Astrophysics Data System (ADS)

The proton spectral and angular distributions simultaneously within the target normal direction and laser propagation direction by using an angle-resolved proton energy spectrometer are studied. For the protons generated in the interactions of 100 fs, 800 nm laser pulses with aluminum foil targets, the deviations of proton beam centers of different energies from the target normal direction towards the laser propagation direction are different. This is probably because of the toroidal magnetic fields generated at the rear target surface, which deflect protons transversely. As a result, protons in low energy range have large deviation angles, protons in middle energy range have the smallest deviation angles, while protons in high energy tail have large deviation angles.

Su, LuNing; Zheng, Yi; Liu, Meng; Hu, ZhiDan; Wang, WeiMin; Yuan, XiaoHui; Xu, MiaoHua; Sheng, ZhengMing; Shen, ZhongWei; Fan, HaiTao; Li, YuTong; Ma, JingLong; Lu, Xin; Chen, LiMing; Wang, ZhaoHua; Wei, ZhiYi; Zhang, Jie

2014-05-01

397

Characterization of proton interactions in electronic components  

SciTech Connect

The aim of this paper is to establish a law to calculate proton-induced Single Event Upset cross-sections from heavy ion-induced cross-section data. For this purpose it is necessary to know how the energy is deposited by protons in silicon. Here, the responses of several electronic devices to 30, 100, 200 MeV protons were experimentally characterized. The results are compared with calculations using the HETC code. Well matching proton-induced SEU cross-sections are deduced.

Doucin, B. (CEA Centre de Bruyeres-le-Chatel (France). Service de Physique et Techniques Nucleaires Matra Marconi Space, Velizy-Villacoublay (France)); Patin, Y.; Lochard, J.P. (CEA Centre de Bruyeres-le-Chatel (France). Service de Physique et Techniques Nucleaires); Beaucour, J.; Carriere, T. (Matra Marconi Space, Velizy-Villacoublay (France)); Isabelle, D. (CNRS/CERI, Orleans (France)); Buisson, J. (CEN Saclay, Gif-sur-Yvette (France)); Corbiere, T.; Bion, T. (MHS, Nantes (France))

1994-06-01

398

Active Proton Interrogation for Homeland Security  

NASA Astrophysics Data System (ADS)

Energetic proton beams may provide an attractive technology for active interrogation of nuclear threats because: they have large fission cross sections, long mean free paths and high penetration, and proton beams can be manipulated with magnetic optics. We have measured time-dependent cross sections for delayed neutrons and gamma rays using 800 MeV protons from the Los Alamos Neutron Science Center and 4 GeV protons from the Brookhaven Alternating Gradient Synchrotron for a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Results will be presented. )

Greene, Steven; Morris, Christopher; Canavan, Gregory; Chung, Kiwhan; Elson, Jay; Hogan, Gary; Makela, Mark; Mariam, Fesseha; Murray, Matthew; Saunders, Alexander; Spaulding, Randy; Wang, Zhehui; Waters, Laurie; Wysocki, Frederick

2010-02-01

399

The Study of Solar Energetic Protons Associated with EUV Waves  

NASA Astrophysics Data System (ADS)

We studied the relationship between solar energetic protons (SEPs) and extreme ultraviolet (EUV) wave properties between 2010 August and 2013 May observed by STEREO, SOHO and SDO. We determined the onset times, peak times and peak fluxes of the SEPs in SOHO ERNE and STEREO LET proton channel (6 - 10 MeV). Full Sun heliographic images created by combining STB 195Å, SDO 193Å, and STA 195Å were used for the analysis of the EUV waves. EUV wave arrival times at the spacecraft connecting points and their speed on the low corona were determined by space-time plots. It is noted that there is a significant correlation between the EUV wave arrival times and SEP onset times (r=0.73) but no SEP peak times. SEP peak fluxes increase with EUV wave speed (r=0.69) and the power law spectral index become harder with the EUV wave speed. This suggests that energetic protons are strongly associated with EUV waves, which is considered as the signature of CME shock in the low corona.

Park, Jinhye; Innes, Davina; Bucik, Radoslav; Moon, Yong-Jae; Kahler, Stephen W.

2014-06-01

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On the development of proton conducting materials for technological applications  

Microsoft Academic Search

Some aspects of the simultaneous optimisation of material properties of proton conductors which are relevant for their use in electrochemical cells such as fuel cells, electrochemical reactors and sensors (high proton conductivity, chemical, electrochemical and morphological stability) are discussed. Suggestions are made for the further development of proton conducting perovskite type oxides, proton conducting polymer membranes and medium temperature proton

K. D Kreuer

1997-01-01

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