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1

A Geometric Flow for Segmenting Vasculature in Proton-Density Weighted MRI  

E-print Network

McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University cCenter for Intelligent geometric flow for segmenting vasculature in PD images, which can also be applied to the easier cases of MR boundaries. We carry out a qualitative validation of the approach on PD, MR angiography and Gadolinium

Siddiqi, Kaleem

2

Proton Therapy Verification with PET Imaging  

PubMed Central

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; Fakhri, Georges El

2013-01-01

3

Recent developments in combining LODESR imaging with proton NMR imaging  

NASA Astrophysics Data System (ADS)

We have designed and constructed RF coil assemblies and the appropriate instrumentation for combining proton NMR imaging with LODESR imaging. This has enabled us to collect sequential images from the same sample using both methods. The coil assembly consists of a crossed ellipse coil for LODESR and proton NMR signal detection and a saddle coil for excitation of the ESR resonance. Images have been collected of phantoms containing copper sulphate and Tempol solutions. NMR images were collected (4.3 min) and within 30 s LODESR data collection started (collection time 2.5 min). Only the Tempol solutions are visible in the LODESR images.

Nicholson, I.; Robb, F. J. L.; McCallum, S. J.; Koptioug, A.; Lurie, D. J.

1998-07-01

4

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

5

Observation of the proton aurora with IMAGE FUV imager and simultaneous ion flux in situ measurements  

E-print Network

Observation of the proton aurora with IMAGE FUV imager and simultaneous ion flux in situ satellite images the aurora in three different spectral regions. One of the channels of the spectrographic to spectrally discriminate between the proton and electron FUV aurora and to globally map the energetic protons

California at Berkeley, University of

6

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

7

The Application of Proton-Electron Double-Resonance Imaging Techniques to Proton Mobility Studies  

NASA Astrophysics Data System (ADS)

A method of analyzing NMR images obtained using proton-electron double-resonance imaging (PEDRI) to image free-radical distributions is presented. The dependence of image intensity on proton mobility within the sample is demonstrated for samples of the nitroxide free radical TEMPOL in water/glycerol mixtures of different viscosities. From the images obtained at a fixed magnetic field strength of 10 mT, the parameters which are responsible for the image dependence on viscosity are determined. Field-cycling techniques are used to measure this dependence as a function of magnetic field strength with a view to defining a single parameter reflecting changes in proton mobility within a sample of unknown concentration.

Nicholson, I.; Lurie, D. J.; Robb, F. J. L.

8

Imaging Intelligence with Proton Magnetic Resonance Spectroscopy  

ERIC Educational Resources Information Center

Proton magnetic resonance spectroscopy ([to the first power]H-MRS) is a technique for the assay of brain neurochemistry "in vivo." N-acetylaspartate (NAA), the most prominent metabolite visible within the [to the first power]H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA-cognition…

Jung, Rex E.; Gasparovic, Charles; Chavez, Robert S.; Caprihan, Arvind; Barrow, Ranee; Yeo, Ronald A.

2009-01-01

9

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

10

Spectral imaging of proton aurora and twilight at Troms, Norway  

E-print Network

Spectral imaging of proton aurora and twilight at Tromsø, Norway M. Galand,1 J. Baumgardner,1 D instruments and demonstrate their capabilities for the study of the H Balmer emissions in twilight and during auroral activity. Our high-resolution spectra taken in twilight could be used to observe the variability

Lummerzheim, Dirk

11

Reverse convection and cusp proton aurora: Cluster, polar and image observation  

E-print Network

Reverse convection and cusp proton aurora: Cluster, polar and image observation Q.-G. Zong a,b,*, TT) at Earth. Cusp proton aurora was caused by the leading phase of the CME. Cusp proton aurora generally of the cusp proton aurora shifted about 30° from dawnside to duskside when IMF By changed from �10 to 5 n

California at Berkeley, University of

12

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

13

Chondromalacia Patellae: Diagnosis with MR Imaging  

Microsoft Academic Search

Most previous studies of MR imaging for detection of chondromalacia have used Ti- weighted images. We correlated findings on axial MR images of the knee with arthro- scopic findings to determine MR findings of chondromalacia patellae on T2-weighted and proton density-weighted images. The study population included 52 patients who had MR examination of the knee with a 15-T unit and

Thomas R. McCauley; Ruben Kier; Kevin J. Lynch; Peter Jokl

14

Proton core imaging of the nuclear burn in inertial confinement fusion implosions  

E-print Network

Proton core imaging of the nuclear burn in inertial confinement fusion implosions J. L. De to measure the nuclear burn regions in the cores of inertial confinement fusion implosions. Three imaging the penetrating 14.7 MeV protons produced from D 3 He fusion reactions to produce emission images of the nuclear

15

Monitoring proton radiation therapy with in-room PET imaging  

NASA Astrophysics Data System (ADS)

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

2011-07-01

16

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. PMID:21677366

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

2011-01-01

17

Fast method for brain image segmentation: application to proton magnetic resonance spectroscopic imaging.  

PubMed

The interpretation of brain metabolite concentrations measured by quantitative proton magnetic resonance spectroscopic imaging (MRSI) is assisted by knowledge of the percentage of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) within each MRSI voxel. Usually, this information is determined from T(1)-weighted magnetic resonance images (MRI) that have a much higher spatial resolution than the MRSI data. While this approach works well, it is time-consuming. In this article, a rapid data acquisition and analysis procedure for image segmentation is described, which is based on collection of several, thick slice, fast spin echo images (FSE) of different contrast. Tissue segmentation is performed with linear "Eigenimage" filtering and normalization. The method was compared to standard segmentation techniques using high-resolution 3D T(1)-weighted MRI in five subjects. Excellent correlation between the two techniques was obtained, with voxel-wise regression analysis giving GM: R2 = 0.893 +/- 0.098, WM: R2 = 0.892 +/- 0.089, ln(CSF): R2 = 0.831 +/- 0.082). Test-retest analysis in one individual yielded an excellent agreement of measurements with R2 higher than 0.926 in all three tissue classes. Application of FSE/EI segmentation to a sample proton MRSI dataset yielded results similar to prior publications. It is concluded that FSE imaging in conjunction with Eigenimage analysis is a rapid and reliable way of segmenting brain tissue for application to proton MRSI. PMID:16187272

Bonekamp, David; Horská, Alena; Jacobs, Michael A; Arslanoglu, Atilla; Barker, Peter B

2005-11-01

18

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

19

Proton emission imaging of the nuclear burn in inertial confinement fusion experiments  

E-print Network

A proton core imaging system has been developed and extensively used for measuring the nuclear burn regions of inertial confinement fusion implosions. These imaging cameras, mounted to the 60-beam OMEGA laser facility, use ...

DeCiantis, Joseph Loreto

2005-01-01

20

He-proton emission imaging for inertial-confinement-fusion experiments (invited)  

E-print Network

D3 He-proton emission imaging for inertial-confinement-fusion experiments (invited) F. H. Séguin. Schwartz, and R. D. Petrassob) Plasma Science and Fusion Center, Massachusetts Institute of Technology, Livermore, California 94550 (Presented on 19 April 2004; published 5 October 2004) Proton emission imaging

21

Longitudinal MR imaging and proton MR spectroscopy in herpes simplex encephalitis  

Microsoft Academic Search

Longitudinal MR imaging and proton MR spectroscopy were performed in an 11 year-old female case of herpes simplex encephalitis with a complete recovery. On MR imaging, the white matter lesions, which could be seen in the subacute stage, but not in the acute or chronic stage, might represent edema due to postinfectious neuroallergic phenomena. Proton MR spectroscopy revealed marked reduction

Jun-ichi Takanashi; Katsuo Sugita; Mitsuko Ishii; Masahiko Aoyagi; Hiroo Niimi

1997-01-01

22

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

23

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 understand these laser-produced protons, we designed and constructed a novel, spatially imaging proton spectrometer that will not only provide at high-resolution the energy distribution, but also the protons angular characteristics. The information obtained from this spectrometer compliments those from other methods using radiochromic film packs, CR39 films and other protons spectrometers. The basic characterizations and example data from this diagnostics will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, as part of the Cimarron project funded by LDRD-09SI11.

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

2010-02-09

24

Image directed proton spectroscopy of gerbil brain at 7 tesla.  

PubMed

Image directed localized 1H NMR spectra were obtained at 7 T (300 MHz) from cubic volumes of less than 40 microL in the gerbil brain. Signals from cerebral metabolites commonly detected in other rodent species were easily assigned, and high resolution spectroscopy (360 MHz) of aqueous brain extracts assisted the tentative identification of partially overlapping resonances from lower concentration compounds like alanine, lysine, gamma-aminobutyrate, valine, leucine and isoleucine. Weak coupling at 7 T was manifest in the resolution of signals from the gamma-CH2 groups of glutamine and glutamate. Down-field of water, signals assigned to purine nucleotides were conspicuous in the extract spectra, but localized spectra acquired routinely in vivo, using selective excitation and gradient crushing (SUBMERGE) for water suppression, exhibited little or no signal from purines. When localized in vivo spectra were acquired without water suppression, however, or using a low power binomial excitation sequence rather than SUBMERGE, a broad signal appeared at the resonant frequency of purine aromatic protons. NMR experiments on the nucleotide adenosine 5'-monophosphate (AMP) in 90% glycerol/10% D2O solution demonstrated that pre-irradiation of the water signal even for less than 100 ms attenuated the nucleotide signal appreciably. This implies that the soft pulses required for selective excitation of water in sequences such as SUBMERGE induce spin-diffusion which eliminates or diminishes the signal from nucleotides in vivo. PMID:8579999

Middleton, D A; Hockings, P D; Glen, S; Reid, D G; Rose, S E; Crozier, S; Roffman, W; Rothaul, A L; Hunter, A J; Doddrell, D M

1995-05-01

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

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

Microsoft Academic Search

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

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

2011-01-01

27

Multivoxel Proton MR Spectroscopy and Hemodynamic MR Imaging of Childhood Brain Tumors: Preliminary Observations  

Microsoft Academic Search

PURPOSE: To assess multivoxel proton MR spectroscopy combined with MR imaging and hemo- dynamic MR imaging in the evaluation of brain tumors in children and young adults. METHODS: Fifteen patients with brain tumors and 10 healthy children underwent MR imaging and MR spec- troscopy on a 1.5-T system. Ten patients with tumors had both MR spectroscopy and hemody- namic MR

A. Aria Tzika; Sridhar Vajapeyam; Patrick D. Barnes

1997-01-01

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

Abstract-Proton Computed Tomography (CT) has important implications for both image-guided diagnosis and radiation  

E-print Network

-guided diagnosis and radiation therapy. For diagnosis, the fact that the patient dose committed by proton CT imaging method to perform planning and verification of proton-based radiation treatment, since proton Computed Tomography (CT) has important implications for both image-guided diagnosis and radiation therapy

California at Santa Cruz, University of

31

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

32

Radiochromic film imaging spectroscopy of laser-accelerated proton beams  

E-print Network

. The acceleration of protons during the laser-plasma in- teraction up to energies above 60 MeV4,7 is qualitatively de- scribed by a plasma expansion model.17 Relativistic electrons generated by the laser-plasma and their energy deposition with respect to further applications. © 2009 American Institute of Physics. DOI: 10

Strathclyde, University of

33

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 PMID:23192776

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

2013-01-01

34

Measuring proton energies and fluxes using EIT (SOHO) CCD areas outside the solar disk images  

E-print Network

An indirect proton flux measuring tool based on discrimination of the energy deposited by protons in 128 x 128 pixel EIT CCD areas outside the solar disk images is presented. Single pixel intensity events are converted into proton incident energy flux using modeled energy deposition curves for angles of incidence 60 deg in four EIT spatial areas with different proton stopping power. The extracted proton flux is corrected for both the loss of one-pixel events in the range of angles of incidence as well as for the contribution to the single pixel events resulting from scattered middle-energy protons (low-energy or high-energy particles are stopped by the EIT components or pass through them, accordingly). A simple geometrical approach was found and applied to correct for a non-unique relation between the proton-associated CCD output signal and the incident proton energy. With this geometrical approximation four unique proton incident energy ranges were determined as 45--49, 145--154, 297--335, and 390--440 MeV. The indirect proton flux measuring tool has been tested by comparing Solar Energetic Particles (SEP) flux temporal profiles extracted from the EIT CCD frames and downloaded from the GOES database for the Bastille Day (BD) of 2000 July 14 and the more recent 2005 January 20 events. The SEP flux temporal profiles and proton spectra extracted from the EIT in the relatively narrow energy ranges between 45 and 440 MeV reported here are consistent with the related GOES profiles. The four additional EIT extracted ranges provide higher energy resolution of the SEP data.

L. V. Didkovsky; D. L. Judge; A. R. Jones; E. J. Rhodes, Jr.; J. B. Gurman

2006-04-20

35

Glioma Grading: Sensitivity, Specificity, and Predictive Values of Perfusion MR Imaging and Proton MR Spectroscopic Imaging Compared with Conventional MR Imaging  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of conventional MR imaging in predicting glioma grade are not high. Relative cerebral blood volume (rCBV) measurements derived from perfusion MR imaging and metabolite ratios from proton MR spectroscopy are useful in predicting glioma grade. We evaluated the sensitivity, specificity, PPV, and NPV of perfusion MR imaging

Meng Law; Stanley Yang; Hao Wang; James S. Babb; Glyn Johnson; Soonmee Cha; Edmond A. Knopp; David Zagzag

2003-01-01

36

Biophysical characterization of a relativistic proton beam for image-guided radiosurgery  

PubMed Central

We measured the physical and radiobiological characteristics of 1 GeV protons for possible applications in stereotactic radiosurgery (image-guided plateau-proton radiosurgery). A proton beam was accelerated at 1 GeV at the Brookhaven National Laboratory (Upton, NY) and a target in polymethyl methacrylate (PMMA) was used. Clonogenic survival was measured after exposures to 1–10 Gy in three mammalian cell lines. Measurements and simulations demonstrate that the lateral scattering of the beam is very small. The lateral dose profile was measured with or without the 20-cm plastic target, showing no significant differences up to 2 cm from the axis A large number of secondary swift protons are produced in the target and this leads to an increase of approximately 40% in the measured dose on the beam axis at 20 cm depth. The relative biological effectiveness at 10% survival level ranged between 1.0 and 1.2 on the beam axis, and was slightly higher off-axis. The very low lateral scattering of relativistic protons and the possibility of using online proton radiography during the treatment make them attractive for image-guided plateau (non-Bragg peak) stereotactic radiosurgery. PMID:22843629

Yu, Zhan; Vanstalle, Marie; La Tessa, Chiara; Jiang, Guo-Liang; Durante, Marco

2012-01-01

37

Sub-second proton imaging of (13) C hyperpolarized contrast agents in water.  

PubMed

Indirect proton detection of (13) C hyperpolarized contrast agents potentially enables greater sensitivity. Presented here is a study of sub-second projection imaging of hyperpolarized (13) C contrast agent addressing the obstacle posed by water suppression for indirect detection in vivo. Sodium acetate phantoms were used to develop and test water suppression and sub-second imaging with frequency-selective RF pulses using spectroscopic and imaging indirect proton detection. A 9.8?mm aqueous solution of (13) C PHIP hyperpolarized 2-hydroxyethyl-(13) C-propionate-d2,3,3 (HEP), ?~25% was used for demonstration of indirect proton sub-second imaging detection. Balanced 2D FSSFP (fast steady-state free precession) allowed the recording of proton images with a field of view of 64?×?64?mm(2) and spatial resolution 2?×?2?mm(2) with total acquisition time of less than 0.2?s. In thermally polarized sodium 1-(13) C-acetate, (13) C to (1) H polarization transfer efficiency of 45.1% of the theoretically predicted values was observed in imaging detection corresponding to an 11-fold overall sensitivity improvement compared with direct (13) C FSSFP imaging. (13) C to (1) H polarization transfer efficiency of 27% was observed in imaging detection, corresponding to a 3.25-fold sensitivity improvement compared with direct (13) C FSSFP imaging with hyperpolarized HEP. The range of potential applications and limitations of this sub-second and ultra-sensitive imaging approach are discussed. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24753438

Truong, Milton L; Coffey, Aaron M; Shchepin, Roman V; Waddell, Kevin W; Chekmenev, Eduard Y

2014-09-01

38

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

39

A density-weighted reacting model for multi-phase turbulent diffusion flames  

NASA Astrophysics Data System (ADS)

A reacting multi-fluid model, based on the Favre-averaged separate transport equations for reactig gas-liquid 'multi-phase' flow, is presented. New density-weighted (Favre-averaged) separate transport equations for multi-phase mixture fraction f and its variance g are derived. The new multi-fluid transport equations for f and g equally applicable to spray flames as well as liquid metal fuel combustors. The fuel spray is discretized into a number of size groups; each group is considered as a separate 'fluid' or 'phase'. A probability density function (pdf) approach to the reaction process is adopted. An evaporation variable e is introduced, which is a measure of a nonequilibrium phase state, defining a two-variable pdf as a function of f and e. The instantaneous thermo-chemical properties are computed from a nonequilibrium model. The predicted results, using the present density-weighted multi-fluid model, for an airblast kerosene spray flame are compared with corresponding experimental data. The present multi-fluid model result are in good agreement with the corresponding experimental data for the whole spray flame length.

Chan, S. H.; Abou-Ellail, M. M. M.

1994-01-01

40

The Proton and Electron Aurora as Seen by Image-FUV and FAST  

NASA Technical Reports Server (NTRS)

The Far Ultraviolet (FUV) instrument on IMAGE images the aurora in three different wavelength regions. The Wideband Imaging Camera (WIC) observes the molecular Lyman-Birge-Hopfield (LBH) and atomic Nitrogen emissions at 140-190 nm. The two channels of the Spectrographic Imager (SI) observe the Doppler shifted Lyman Alpha emission of precipitating protons at 121.8 nm (SI 12) and the mostly electron produced emission from oxygen OI at 135.6 nm (SI13). The major advantage of FUV compared to previously flown UV imagers is the simultaneous operation of all three imaging systems without the need for filter changes and the uncertainty of temporal changes of the aurora between exposures. The FAST satellite passes every two hours through FUV images during apogee operations. This enables a comparison between the remotely imaged particle precipitation and the in-situ measurements along the FAST track. The detailed analysis of images from all three systems together with a full simulation of auroral emissions based on in-situ measurements by FAST confirms the laboratory calibrations of FUV. The spatial resolution and image quality of WIC permits the observation of a good correspondence between in-situ and remote measurements of precipitation boundaries. The clear separation between the lower latitude proton precipitation and the more structured higher latitude electron precipitation is obtained with both SI-channels.

Gerard, J.-C.; Hubert, B.; Habraken, S.; Renotte, E.; Jamar, C.; Rochus, P.; Spann, J.; Gladstone, R.; Rose, M. Franklin (Technical Monitor)

2000-01-01

41

Nuclear magnetic resonance proton imaging of bone pathology  

SciTech Connect

Thirty-two patients with diversified pathology were examined with a supraconductive NMR imager using spin echo with different TR and TE to obtain T1 and T2 weighted images. They included 20 tumors (12 primary, eight metastasis), six osteomyelitis, three fractures, two osteonecrosis, and one diffuse metabolic (Gaucher) disease. In all cases except for the stress fractures, the bone pathology was clearly visualized in spite of the normal lack of signal from the compact cortical bone. Nuclear magnetic resonance (NMR) imaging proved to be at least as sensitive as radionuclide scintigraphy but much more accurate than all other imaging procedures including computed tomography (CT) and angiography to assess the extension of the lesions, especially in tumors extended to soft tissue. This is due both to easy acquisition of sagittal and coronal sections and to different patterns of pathologic modifications of T1 and T2 which are beginning to be defined. It is hoped that more experience in clinical use of these patterns will help to discriminate between tumor extension and soft-tissue edema. We conclude that while radionuclide scintigraphy will probably remain the most sensitive and easy to perform screening test for bone pathology, NMR imaging, among noninvasive diagnostic procedures, appears to be at least as specific as CT. In addition, where the extension of the lesions is concerned, NMR imaging is much more informative than CT. In pathology of the spine, the easy visualization of the spinal cord should decrease the need for myelography.

Atlan, H.; Sigal, R.; Hadar, H.; Chisin, R.; Cohen, I.; Lanir, A.; Soudry, M.; Machtey, Y.; Schreiber, R.; Benmair, J.

1986-02-01

42

Proton magnetic spectroscopic imaging of the child's brain: the response of tumors to treatment  

Microsoft Academic Search

Our aim was to determine and\\/or predict response to treatment of brain tumors in children using proton magnetic resonance\\u000a spectroscopic imaging (MRSI). We studied 24 patients aged 10 months to 24 years, using MRI and point-resolved spectroscopy\\u000a (PRESS; TR 2000 TE 65 ms) with volume preselection and phase-encoding in two dimensions on a 1.5 T imager. Multiple logistic\\u000a regression was

A. A. Tzika; D. Zurakowski; T. Young Poussaint; L. Goumnerova; L. G. Astrakas; P. D. Barnes; D. C. Anthony; A. L. Billett; N. J. Tarbell; R. M. Scott; P. Mc L. Black

2001-01-01

43

MR imaging of fat-containing tissues: valuation of two quantitative imaging techniques in comparison with localized proton spectroscopy.  

PubMed

Since lipid protons, consisting mainly of triacylglycerols (TAG), are rather mobile, magnetic resonance imaging (MRI) is ideally suited for the examination of fat-containing tissues such as bone marrow. In contrast to water protons, however, lipid protons are chemically distinct and give rise to at least eight resonance peaks with different T1 and T2 relaxation times in the 1H spectrum. This is why the characterization of fat-containing tissues by quantitative MRI is much more difficult than that of most other tissues. In our study we wanted to examine the accuracy and the potential of a 1H chemical shift imaging (CSI) technique and a multiple spin-echo imaging (MSEI) technique. A stimulated-echo (STEAM) sequence for spatially localized proton spectroscopy was used as the reference method. In the first part of this paper, we describe quantitative imaging experiments which were performed to assess the accuracy of the fat-water separation according to the Dixon method and the bi-exponential decomposition of the MSEI data. For that purpose, we used a two-compartment phantom filled with either an aqueous Gd-DTPA solution and vegetable oil or with two different aqueous Gd-DTPA solutions, respectively. The analysis of the 1H CSI data revealed that the presence of non-methylen protons in neutral fats leads to a slight under-estimation (of about 15%) of the relative fat fraction. The error is described theoretically and verified quantitatively by STEAM measurements. The bi-exponential analysis of the transverse relaxation data, on the other hand, yields reliable T2 values if the relative proton density of both components is higher than 15%. IN the second part of our investigation, the same techniques were applied to acquire data from the subcutaneous fatty tissue, the femoral head, and the lumbar vertebrae of three healthy volunteers. In the bone marrow spectra, only two broad resonances could be resolved; they were superpositions of diverse molecular groups with different T1 and T2 relaxation times. In these cases, localized proton spectroscopy does not provide additional information with respect to 1H CSI. The MSEI data of the three examined fat containing tissue regions were adequately fitted by a bi-exponential function despite the fact that there were much more chemically distinct protons present in fatty tissues. PMID:8231682

Brix, G; Heiland, S; Bellemann, M E; Koch, T; Lorenz, W J

1993-01-01

44

Two parameter model of Fuji imaging plate response function to protons  

NASA Astrophysics Data System (ADS)

Imaging plates are phosphor films routinely used in ultra high intensity laser experiments. They offer the possibilities of both imaging the beams of ionizing particles generated in the laser-matter interaction and characterizing their energy distribution. The response functions of the imaging plates are necessary to relate the detected signal intensity to the absolute flux of incoming particles. In this report we review our model of the response functions and discuss its parameters. We detail how we calibrated the parameters of the response functions to protons from absolute measurements. Their uncertainties are also presented.

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

2013-05-01

45

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

NASA Astrophysics Data System (ADS)

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-section 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.

España, S.; Zhu, X.; Daartz, J.; El Fakhri, G.; Bortfeld, T.; Paganetti, H.

2011-05-01

46

Simultaneous Cluster and IMAGE observations of cusp reconnection and auroral proton spot for northward IMF  

NASA Astrophysics Data System (ADS)

On March 18, 2002, under northward interplanetary magnetic field (IMF) and high (~15 nPa) solar wind dynamic pressure conditions, Cluster observed reconnection signatures and the passage of an X-line at the large (~175°) magnetic-shear high-latitude magnetopause (MP). The observations are consistent with the occurrence of a reconnection site tailward of the cusp and in the vicinity of the spacecraft. At the same time IMAGE observed a bright spot poleward of the dayside auroral oval resulting from precipitating protons into the atmosphere. The intensity of the proton spot is consistent with the energy flux contained in the plasma jets observed by Cluster. Using the Tsyganenko-01 magnetic field model with enhanced solar wind pressure, the Cluster MP location is mapped to the vicinity of the IMAGE proton spot. Mapping the auroral spot out to the MP implies an X-line of at least 3.6 RE in yGSM. In addition to confirming the reconnection source of the dayside auroral proton spot, the Cluster observations also reveal sub-Alfvénic flows and a plasma depletion layer in the magnetosheath next to the MP, in a region where gas dynamic models predict super-Alfvénic flows.

Phan, T.; Frey, H. U.; Frey, S.; Peticolas, L.; Fuselier, S.; Carlson, C.; Rème, H.; Bosqued, J.-M.; Balogh, A.; Dunlop, M.; Kistler, L.; Mouikis, C.; Dandouras, I.; Sauvaud, J.-A.; Mende, S.; McFadden, J.; Parks, G.; Moebius, E.; Klecker, B.; Paschmann, G.; Fujimoto, M.; Petrinec, S.; Marcucci, M. F.; Korth, A.; Lundin, R.

2003-05-01

47

Predicting image blur in proton radiography: comparisons between measurements and Monte Carlo simulations  

SciTech Connect

Given the cost and lead-times involved in high-energy proton radiography, it is prudent to model proposed radiographic experiments to see if the images predicted would return useful information. We recently modified our raytracing transmission radiography modeling code HADES to perform simplified Monte Carlo simulations of the transport of protons in a proton radiography beamline. Beamline objects include the initial diffuser, vacuum magnetic fields, windows, angle-selecting collimators, and objects described as distorted 2D (planar or cylindrical) meshes or as distorted 3D hexahedral meshes. We present an overview of the algorithms used for the modeling and code timings for simulations through typical 2D and 3D meshes. We next calculate expected changes in image blur as scattering materials are placed upstream and downstream of a resolution test object (a 3 mm thick sheet of tantalum, into which 0.4 mm wide slits have been cut), and as the current supplied to the focusing magnets is varied. We compare and contrast the resulting simulations with the results of measurements obtained at the 800 MeV Los Alamos LANSCE Line-C proton radiography facility.

von Wittenau, A; Aufderheide, M B; Henderson, G L

2010-05-07

48

Measurement of regional brain temperature using proton spectroscopic imaging: validation and application to acute ischemic stroke  

Microsoft Academic Search

A magnetic resonance proton spectroscopic imaging (SI) technique was developed to measure regional brain temperatures in human subjects. The technique was validated in a homogeneous phantom and in four healthy volunteers. Simulations and calculations determined the theoretical measurement precision as approximately ±0.3°C for individual 1-ml voxels. In healthy volunteers, repeated measurements on individual voxels had an S.D.=1.2°C. In a clinical

Ian Marshall; Bartosz Karaszewski; Joanna M. Wardlaw; Vera Cvoro; Karolina Wartolowska; Paul A. Armitage; Trevor Carpenter; Mark E. Bastin; Andrew Farrall; Kristin Haga

2006-01-01

49

Prompt gamma imaging of proton pencil beams at clinical dose rate  

NASA Astrophysics Data System (ADS)

In this work, we present experimental results of a prompt gamma camera for real-time proton beam range verification. The detection system features a pixelated Cerium doped lutetium based scintillation crystal, coupled to Silicon PhotoMultiplier arrays, read out by dedicated electronics. The prompt gamma camera uses a knife-edge slit collimator to produce a 1D projection of the beam path in the target on the scintillation detector. We designed the detector to provide high counting statistics and high photo-detection efficiency for prompt gamma rays of several MeV. The slit design favours the counting statistics and could be advantageous in terms of simplicity, reduced cost and limited footprint. We present the description of the realized gamma camera, as well as the results of the characterization of the camera itself in terms of imaging performance. We also present the results of experiments in which a polymethyl methacrylate phantom was irradiated with proton pencil beams in a proton therapy center. A tungsten slit collimator was used and prompt gamma rays were acquired in the 3-6 MeV energy range. The acquisitions were performed with the beam operated at 100 MeV, 160 MeV and 230 MeV, with beam currents at the nozzle exit of several nA. Measured prompt gamma profiles are consistent with the simulations and we reached a precision (2?) in shift retrieval of 4 mm with 0.5 × 108, 1.4 × 108 and 3.4 × 108 protons at 100, 160 and 230 MeV, respectively. We conclude that the acquisition of prompt gamma profiles for in vivo range verification of proton beam with the developed gamma camera and a slit collimator is feasible in clinical conditions. The compact design of the camera allows its integration in a proton therapy treatment room and further studies will be undertaken to validate the use of this detection system during treatment of real patients.

Perali, I.; Celani, A.; Bombelli, L.; Fiorini, C.; Camera, F.; Clementel, E.; Henrotin, S.; Janssens, G.; Prieels, D.; Roellinghoff, F.; Smeets, J.; Stichelbaut, F.; Vander Stappen, F.

2014-10-01

50

Knowledge-based image processing for proton therapy planning of ocular tumors  

NASA Astrophysics Data System (ADS)

Our project is concerned with the improvement of radiation treatment procedures for ocular tumors. In this context the application of proton beams offers new possibilities to considerably enhance precision and reliability of current radiation treatment systems. A precise model of the patient's eye and the tumor is essential for determining the necessary treatment plan. Current treatment systems base their irradiation plan calculations mainly on schematic eye models (e.g., Gullstrand's schematic eye). The adjustment of the model to the patient's anatomy is done by distorting the model according to information from ultrasound and/or CT images. In our project a precise model of the orbita is determined from CT, high resolution MRT, ultrasound (A-mode depth images and/or 2D B-mode images) and photographs of the fundus. The results from various segmentation and image analysis steps performed on all the data are combined to achieve an eye model of improved precision. By using a proton cannon for the therapy execution, the high precision of the model can be exploited, thus achieving a basic improvement of the therapy. Control over the destruction of the tumor can be increased by maximizing the dose distributions within the target volume keeping the damage in the surrounding tissue to a minimum. This article is concerned with the image processing to generate an eye model on which treatment planning is based.

Noeh, Sebastian; Haarbeck, Klaus; Bornfeld, Norbert; Tolxdorff, Thomas

1998-06-01

51

Advances in functional and structural imaging of the human lung using proton MRI.  

PubMed

The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed depiction of airway disease. Although there is opportunity for further optimization, such approaches to structural lung imaging are ready for clinical testing. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24990096

Miller, G Wilson; Mugler, John P; Sá, Rui C; Altes, Talissa A; Prisk, G Kim; Hopkins, Susan R

2014-12-01

52

Development of a GEM-based Imaging Detector for Small Field Dosimetry for Proton Therapy Beams  

NASA Astrophysics Data System (ADS)

In order to fully utilize the advantages of proton therapy, the beam range, the beam alignment with the tumor and the real-time dose distribution must be accurately known. Small proton fields (with characteristic sizes of less than 3 cm) are often used in radiosurgery, ophthalmic treatments, and as patch fields to augment dose distributions. Accurate planning and quality assurance of such fields are challenging. Gas electron multiplier (GEM)-based dose imaging detectors are capable of providing improved position resolution, dose rate linearity, fast response and accurate reproduction of depth-dose distributions. The purpose of this project is to develop a double-GEM dose imaging detector with the optical readout of scintillation light using a CCD camera, intended for small field measurements. The detector was tested in a 205 MeV proton beam at the Indiana University Cyclotron, during the Indiana University Physics 2012 REU funded by the NSF. It demonstrated linearity in dose rate up to 75 Gy/min. Lateral profiles measured with the GEM detector and radiochromic film agree within 0.4 mm (one pixel size) at 50% isodose. After initial start-up, the detector response was stable within ±5% over a 40 hour time period.

France, Erin; Klyachko, Alexander; Nichiporov, Dmitri

2012-10-01

53

Comparison of scintillators for single shot imaging of laser accelerated proton beams  

NASA Astrophysics Data System (ADS)

The application of intense laser pulses incident on specialized targets provides exciting new means for generating energetic beams of protons and ions. Recent work has demonstrated the utility of these beams of particles in a variety of applications, from inertial confinement fusion to radiation therapy. These applications require precise control, and subsequently precise feedback from the beam. Imaging techniques can provide the necessary shot-to-shot characterization to be effective as diagnostics. However, the utility of imaging methods scales with the capability of scintillating materials to emit well characterized and consistent radiation upon irradiance by a charged particle beam. We will discuss three candidates for an ideal diagnostic for MeV range protons and light ions. CsI:Tl^+ and Al2O3:Cr^3+ are two inorganic scintillators which exhibit excellent response to hadrons in this energy range. They are compared with the combination diagnostic micro-channel plate with a P43 phosphor screen, which offers advantages in refresh rate and resolution over direct exposure methods. Ultimately we will determine which candidate performs optimally as part of a robust, inexpensive diagnostic for laser accelerated protons and light ions.

Cook, Nathan

2012-03-01

54

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

55

Identification and characterization of tissues by T2-selective whole-body proton NMR imaging.  

PubMed

T2-selective proton imaging at 10 MHz is based on a Carr-Purcell-Meiboom-Gill pulse sequence with at least 36 echoes and 2 tau greater than or equal to 6 ms employing the projection reconstruction technique. The transverse magnetization decay of the volume elements is multiexponential composed of up to three monoexponential T2 components. The T2 values are arranged in T2 histograms which are slice specific. T2 windows are defined in the T2 histogram and used for imaging and for selecting T2 values which are assigned to proton classes and tissues. Tissue characterization is based on the visualization of differences in T2 behavior. The T2 values are transformed into 256 gray levels or, by use of a red-green-blue lookup table, into a rainbow code. Two display techniques have been developed and implemented in the RWTH Aachen Magnetic Resonance Software System (RAMSES): (i) for nonselective T2 imaging with secondary T2 selection and encoding of molecular classes on the basis of T2 values; (ii) for T2-selective imaging by employing combined primary and secondary T2 selection and encoding particular tissues and variations therein. The tissues can be identified by selecting different classes of molecules, like water, lipids, and proteins, when shifting the primary T2 window on the T2 axis of the T2 histogram. PMID:4094553

Gersonde, K; Tolxdorff, T; Felsberg, L

1985-08-01

56

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

57

Imaging the proton concentration and mapping the spatial distribution of the electric field of catalytic micropumps  

E-print Network

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 chemo-mechanical actuation of catalytic pumps. Our experimental approach could be used to study other electrochemical systems with heterogeneous electrodes.

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

2013-11-13

58

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

59

Multislice proton magnetic resonance spectroscopic imaging in X-linked adrenoleukodystrophy.  

PubMed

Multislice proton magnetic resonance spectroscopic imaging permits metabolic analysis of brain tissue in vivo by data acquisition in four oblique axial slices, each 15-mm thick and divided into 0.8-ml single-volume elements. We applied this technique to the systematic study of 25 patients with adrenoleukodystrophy: 3 with the severe childhood or adult cerebral form of the disease, 5 with adrenomyeloneuropathy, 12 with no demonstrable neurological involvement, and 5 women heterozygous for adrenoleukodystrophy who had some degree of neurological disability. Abnormalities on magnetic resonance spectroscopic imaging included a reduction in N-acetyl aspartate, an increase in choline-containing compounds, and at times, an increase in lactate. Five patients showed abnormalities in the presence of normal-appearing magnetic resonance images, and in 8 other patients the alterations on spectroscopic images were more severe than those demonstrable by magnetic resonance imaging. Correlation with clinical course suggests that an increase in the choline-containing compounds is associated with an active demyelinative process, whereas such compounds are not elevated in lesions that are stable. We conclude that magnetic resonance spectroscopic imaging is a more sensitive indicator of early neurological involvement than is magnetic resonance imaging, and that the character of abnormalities detected by the former technique may serve as a gauge of the degree of activity of the demyelinating process and as a guide to the selection and evaluation of therapeutic approaches. PMID:7944292

Kruse, B; Barker, P B; van Zijl, P C; Duyn, J H; Moonen, C T; Moser, H W

1994-10-01

60

Introducing an on-line adaptive procedure for prostate image guided intensity modulate proton therapy  

NASA Astrophysics Data System (ADS)

With on-line image guidance (IG), prostate shifts relative to the bony anatomy can be corrected by realigning the patient with respect to the treatment fields. In image guided intensity modulated proton therapy (IG-IMPT), because the proton range is more sensitive to the material it travels through, the realignment may introduce large dose variations. This effect is studied in this work and an on-line adaptive procedure is proposed to restore the planned dose to the target. A 2D anthropomorphic phantom was constructed from a real prostate patient's CT image. Two-field laterally opposing spot 3D-modulation and 24-field full arc distal edge tracking (DET) plans were generated with a prescription of 70 Gy to the planning target volume. For the simulated delivery, we considered two types of procedures: the non-adaptive procedure and the on-line adaptive procedure. In the non-adaptive procedure, only patient realignment to match the prostate location in the planning CT was performed. In the on-line adaptive procedure, on top of the patient realignment, the kinetic energy for each individual proton pencil beam was re-determined from the on-line CT image acquired after the realignment and subsequently used for delivery. Dose distributions were re-calculated for individual fractions for different plans and different delivery procedures. The results show, without adaptive, that both the 3D-modulation and the DET plans experienced delivered dose degradation by having large cold or hot spots in the prostate. The DET plan had worse dose degradation than the 3D-modulation plan. The adaptive procedure effectively restored the planned dose distribution in the DET plan, with delivered prostate D98%, D50% and D2% values less than 1% from the prescription. In the 3D-modulation plan, in certain cases the adaptive procedure was not effective to reduce the delivered dose degradation and yield similar results as the non-adaptive procedure. In conclusion, based on this 2D phantom study, by updating the proton pencil beam energy from the on-line image after realignment, this on-line adaptive procedure is necessary and effective for the DET-based IG-IMPT. Without dose re-calculation and re-optimization, it could be easily incorporated into the clinical workflow.

Zhang, M.; Westerly, D. C.; Mackie, T. R.

2011-08-01

61

Subacute Sclerosing Panencephalitis Findings at MR Imaging, Diffusion MR Imaging, and Proton MR Spectroscopy  

Microsoft Academic Search

Summary: A case of subacute sclerosing panencephalitis in a 2-year-old boy is reported. In addition to asymmetric lesions in the parietotemporal lobes, right thalamus, and globus pallidus, symmetric patterns were notable in the brain stem, middle cerebellar pedincles, and dentate nu- clei. Proton MR spectroscopy revealed markedly decreased N-acetylaspartate peaks and normal choline and myo- inositol levels in the lesions.

R. Nuri Sener

62

The effects of mapping CT images to Monte Carlo materials on GEANT4 proton simulation accuracy  

SciTech Connect

Purpose: Monte Carlo simulations of radiation therapy require conversion from Hounsfield units (HU) in CT images to an exact tissue composition and density. The number of discrete densities (or density bins) used in this mapping affects the simulation accuracy, execution time, and memory usage in GEANT4 and other Monte Carlo code. The relationship between the number of density bins and CT noise was examined in general for all simulations that use HU conversion to density. Additionally, the effect of this on simulation accuracy was examined for proton radiation. Methods: Relative uncertainty from CT noise was compared with uncertainty from density binning to determine an upper limit on the number of density bins required in the presence of CT noise. Error propagation analysis was also performed on continuously slowing down approximation range calculations to determine the proton range uncertainty caused by density binning. These results were verified with Monte Carlo simulations. Results: In the presence of even modest CT noise (5 HU or 0.5%) 450 density bins were found to only cause a 5% increase in the density uncertainty (i.e., 95% of density uncertainty from CT noise, 5% from binning). Larger numbers of density bins are not required as CT noise will prevent increased density accuracy; this applies across all types of Monte Carlo simulations. Examining uncertainty in proton range, only 127 density bins are required for a proton range error of <0.1 mm in most tissue and <0.5 mm in low density tissue (e.g., lung). Conclusions: By considering CT noise and actual range uncertainty, the number of required density bins can be restricted to a very modest 127 depending on the application. Reducing the number of density bins provides large memory and execution time savings in GEANT4 and other Monte Carlo packages.

Barnes, Samuel; McAuley, Grant; Slater, James [Department of Radiation Medicine, Loma Linda University, Loma Linda, California 92350 (United States); Wroe, Andrew [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92350 (United States)

2013-04-15

63

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

64

Early Outcomes From Three Prospective Trials of Image-Guided Proton Therapy for Prostate Cancer  

SciTech Connect

Purpose: To report early outcomes with image-guided proton therapy for prostate cancer. Methods and Materials: We accrued 211 prostate cancer patients on prospective Institutional Review Board-approved trials of 78 cobalt gray equivalent (CGE) in 39 fractions for low-risk disease, dose escalation from 78 to 82 CGE for intermediate-risk disease, and 78 CGE with concomitant docetaxel followed by androgen deprivation for high-risk disease. Minimum follow-up was 2 years. Results: One intermediate-risk patient and 2 high-risk patients had disease progression. Pretreatment genitourinary (GU) symptom management was required in 38% of patients. A cumulative 88 (42%) patients required posttreatment GU symptom management. Four transient Grade 3 GU toxicities occurred, all among patients requiring pretreatment GU symptom management. Multivariate analysis showed correlation between posttreatment GU 2+ symptoms and pretreatment GU symptom management (p < 0.0001) and age (p = 0.0048). Only 1 Grade 3+ gastrointestinal (GI) symptom occurred. The prevalence of Grade 2+ GI symptoms was 0 (0%), 10 (5%), 12 (6%), and 8 (4%) at 6, 12, 18, and 24 months, with a cumulative incidence of 20 (10%) patients at 2 years after proton therapy. Univariate and multivariate analyses showed significant correlation between Grade 2+ rectal bleeding and proctitis and the percentage of rectal wall (rectum) receiving doses ranging from 40 CGE (10 CGE) to 80 CGE. Conclusions: Early outcomes with image-guided proton therapy suggest high efficacy and minimal toxicity with only 1.9% Grade 3 GU symptoms and <0.5% Grade 3 GI toxicities.

Mendenhall, Nancy P., E-mail: menden@shands.ufl.edu [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Li Zuofeng; Hoppe, Bradford S.; Marcus, Robert B.; Mendenhall, William M.; Nichols, R. Charles; Morris, Christopher G. [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Williams, Christopher R.; Costa, Joseph [Division of Urology, College of Medicine, University of Florida, Jacksonville, FL (United States); Henderson, Randal [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

2012-01-01

65

Metabolic Imaging of Human Kidney Triglyceride Content: Reproducibility of Proton Magnetic Resonance Spectroscopy  

PubMed Central

Objective To assess the feasibility of renal proton magnetic resonance spectroscopy for quantification of triglyceride content and to compare spectral quality and reproducibility without and with respiratory motion compensation in vivo. Materials and Methods The Institutional Review Board of our institution approved the study protocol, and written informed consent was obtained. After technical optimization, a total of 20 healthy volunteers underwent renal proton magnetic resonance spectroscopy of the renal cortex both without and with respiratory motion compensation and volume tracking. After the first session the subjects were repositioned and the protocol was repeated to assess reproducibility. Spectral quality (linewidth of the water signal) and triglyceride content were quantified. Bland-Altman analyses and a test by Pitman were performed. Results Linewidth changed from 11.5±0.4 Hz to 10.7±0.4 Hz (all data pooled, p<0.05), without and with respiratory motion compensation respectively. Mean % triglyceride content in the first and second session without respiratory motion compensation were respectively 0.58±0.12% and 0.51±0.14% (P?=?NS). Mean % triglyceride content in the first and second session with respiratory motion compensation were respectively 0.44±0.10% and 0.43±0.10% (P?=?NS between sessions and P?=?NS compared to measurements with respiratory motion compensation). Bland-Altman analyses showed narrower limits of agreement and a significant difference in the correlated variances (correlation of ?0.59, P<0.05). Conclusion Metabolic imaging of the human kidney using renal proton magnetic resonance spectroscopy is a feasible tool to assess cortical triglyceride content in humans in vivo and the use of respiratory motion compensation significantly improves spectral quality and reproducibility. Therefore, respiratory motion compensation seems a necessity for metabolic imaging of renal triglyceride content in vivo. PMID:23620813

de Heer, Paul; Bizino, Maurice B.; Wolterbeek, Ron; Rabelink, Ton J.; Doornbos, Joost; Lamb, Hildo J.

2013-01-01

66

A GEM-based dose imaging detector with optical readout for proton radiotherapy  

NASA Astrophysics Data System (ADS)

New techniques in proton radiation therapy and advances in beam delivery systems design such as beam scanning require accurate 2D dosimetry systems to verify the delivered dose distribution. Dose imaging detectors based on gas electron multipliers (GEMs) are capable of providing high sensitivity, improved dose measurement linearity, position resolution, fast response and accurate characterization of depth-dose distributions. In this work, we report on the development of a GEM-based dose imaging detector with optical readout using a CCD camera. A 10×10 cm2 detector has been tested in a 205 MeV proton beam in single- and double-GEM configurations. The detector demonstrates linearity in dose rate up to 100 Gy/min and position resolution (?) of 0.42 mm. Transverse non-uniformity of the detector response is ?10% before correction and the stability of the detector output throughout the day is within ±1%, with day-to-day reproducibility of about 10%. The depth-dose response of the detector is close to that of a wide-aperture air-filled ionization chamber and is in good agreement with Monte Carlo simulations.

Klyachko, A. V.; Moskvin, V.; Nichiporov, D. F.; Solberg, K. A.

2012-12-01

67

In vivo verification of proton beam path by using post-treatment PET/CT imaging  

SciTech Connect

Purpose: The purpose of this study is to establish the in vivo verification of proton beam path by using proton-activated positron emission distributions. Methods: A total of 50 PET/CT imaging studies were performed on ten prostate cancer patients immediately after daily proton therapy treatment through a single lateral portal. The PET/CT and planning CT were registered by matching the pelvic bones, and the beam path of delivered protons was defined in vivo by the positron emission distribution seen only within the pelvic bones, referred to as the PET-defined beam path. Because of the patient position correction at each fraction, the marker-defined beam path, determined by the centroid of implanted markers seen in the post-treatment (post-Tx) CT, is used for the planned beam path. The angular variation and discordance between the PET- and marker-defined paths were derived to investigate the intrafraction prostate motion. For studies with large discordance, the relative location between the centroid and pelvic bones seen in the post-Tx CT was examined. The PET/CT studies are categorized for distinguishing the prostate motion that occurred before or after beam delivery. The post-PET CT was acquired after PET imaging to investigate prostate motion due to physiological changes during the extended PET acquisition. Results: The less than 2 deg. of angular variation indicates that the patient roll was minimal within the immobilization device. Thirty of the 50 studies with small discordance, referred as good cases, show a consistent alignment between the field edges and the positron emission distributions from the entrance to the distal edge. For those good cases, average displacements are 0.6 and 1.3 mm along the anterior-posterior (D{sub AP}) and superior-inferior (D{sub SI}) directions, respectively, with 1.6 mm standard deviations in both directions. For the remaining 20 studies demonstrating a large discordance (more than 6 mm in either D{sub AP} or D{sub SI}), 13 studies, referred as motion-after-Tx cases, also show large misalignment between the field edge and the positron emission distribution in lipomatous tissues around the prostate. These motion-after-Tx cases correspond to patients with large changes in volume of rectal gas between the post-Tx and the post-PET CTs. The standard deviations for D{sub AP} and D{sub SI} are 5.0 and 3.0 mm, respectively, for these motion-after-Tx cases. The final seven studies, referred to as position-error cases, which had a large discordance but no misalignment, were found to have deviations of 4.6 and 3.6 mm in D{sub AP} and D{sub SI}, respectively. The position-error cases correspond to a large discrepancy on the relative location between the centroid and pelvic bones seen in post-Tx CT and recorded x-ray radiographs. Conclusions: Systematic analyses of proton-activated positron emission distributions provide patient-specific information on prostate motion ({sigma}{sub M}) and patient position variability ({Sigma}{sub p}) during daily proton beam delivery. The less than 2 mm of displacement variations in the good cases indicates that population-based values of {Sigma}{sub p} and {sigma}{sub M} used in margin algorithms for treatment planning at the authors' institution are valid for the majority of cases. However, a small fraction of PET/CT studies (approximately 14%) with {approx}4 mm displacement variations may require different margins. Such data are useful in establishing patient-specific planning target volume margins.

Hsi, Wen C.; Indelicato, Daniel J.; Vargas, Carlos; Duvvuri, Srividya; Li Zuofeng; Palta, Jatinder [Proton Therapy Institute, University of Florida, Jacksonville, Florida 32206 (United States); Boca Radiation Oncology Associates, Boca Raton, Florida 33431 (United States); Proton Therapy Institute, University of Florida, Jacksonville, Florida 32206 (United States); Department of Radiation Oncology, University of Florida, Gainesville, Florida 32610 (United States)

2009-09-15

68

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. PMID:22887123

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

2012-01-01

69

Amide Proton Transfer Imaging of the Human Breast at 7 Tesla: Development and Reproducibility  

PubMed Central

Chemical exchange saturation transfer (CEST) can offer information about protons associated with mobile proteins through the amide proton transfer (APT) effect, which has been shown to discriminate tumor from healthy tissue and, more recently, has been suggested as a prognosticator of response to therapy. Despite this promise, APT effects are small (only a few percent of the total signal); and APT imaging is often prone to artifacts resulting from system instability. Here we present a procedure that enables the detection of APT effects in the human breast at 7 T while mitigating these issues. Adequate signal-to-noise ratio (SNR) was achieved via an optimized quadrature RF breast coil and 3D acquisitions. To reduce the influence of fat, effective fat suppression schemes were developed that did not degrade SNR. To reduce the levels of ghosting artifacts, dummy scans have been integrated into the scanning protocol. Compared to results obtained at 3 T, the standard deviation of the measured APT effect was reduced by a factor of four at 7 T, allowing for the detection of APT effects with a standard deviation of 1% in the human breast at 7 T. Together, these results demonstrate that the APT effect can be reliably detected in the healthy human breast with a high level of precision at 7 T. PMID:23559550

Klomp, Dennis W. J.; Dula, Adrienne N.; Arlinghaus, Lori R.; Italiaander, Michel; Dortch, Richard D.; Zu, Zhongliang; Williams, Jason M.; Gochberg, Daniel F.; Luijten, Peter R.; Gore, John C.; Yankeelov, Thomas E.; Smith, Seth A.

2013-01-01

70

Two-Dimensional Proton Chemical-Shift Imaging of Human Muscle Metabolites  

NASA Astrophysics Data System (ADS)

Large lipid signals and strong susceptibility gradients introduced by muscle-bone interfaces represent major technical challenges for in vivoproton MRS of human muscle. Here, the demonstration of two-dimensional proton chemical-shift imaging of human muscle metabolites is presented. This technique utilizes a chemical-shift-selective method for water and lipid suppression and automatic shimming for optimal homogeneity of the magnetic field. The 2D 1H CSI technique described facilitates the acquisition of high-spatial-resolution spectra, and allows one to acquire data from multiple muscle groups in a single experiment. A preliminary investigation utilizing this technique in healthy adult males ( n= 4) revealed a highly significant difference in the ratio of the creatine to trimethylamine resonance between the fast and slow twitch muscle groups examined. The technique is robust, can be implemented on a commercial scanner with relative ease, and should prove to be a useful tool for both clinical and basic investigators.

Hu, Jiani; Willcott, M. Robert; Moore, Gregory J.

1997-06-01

71

Imaging central neurochemical alterations in chronic pain with proton magnetic resonance spectroscopy.  

PubMed

Proton magnetic resonance spectroscopy has been used extensively in the study of various neurobiological disorders: depression, schizophrenia, autism, etc. But its application to chronic pain is relatively new. Not many studies in chronic pain have used (1)H-MRS. The unique ability of (1)H-MRS to assess both static and dynamic levels of glutamate and ?-aminobutyric acid (GABA) gives this method a unique position in neuroscience. Emerging evidence in chronic pain suggests an elevated excitatory/inhibitory neurotransmitter ratio is present within brain regions involved in pain processing. The combination of (1)H-MRS imaging with pharmacologic interventions holds significant promise as a direct one-to-one matching of disease pathology with drug mechanism of action can be made. As such (1)H-MRS may be useful in discovery of novel compounds for chronic pain. Research in these areas may lead to improved diagnosis and treatment of these complex patients. PMID:22445845

Harris, Richard E; Clauw, Daniel J

2012-06-29

72

Nonalcoholic Fatty Liver Disease: MR Imaging of Liver Proton Density Fat Fraction to Assess Hepatic Steatosis  

PubMed Central

Purpose: To evaluate the diagnostic performance of magnetic resonance (MR) imaging–estimated proton density fat fraction (PDFF) for assessing hepatic steatosis in nonalcoholic fatty liver disease (NAFLD) by using centrally scored histopathologic validation as the reference standard. Materials and Methods: This prospectively designed, cross-sectional, internal review board–approved, HIPAA-compliant study was conducted in 77 patients who had NAFLD and liver biopsy. MR imaging–PDFF was estimated from magnitude-based low flip angle multiecho gradient-recalled echo images after T2* correction and multifrequency fat modeling. Histopathologic scoring was obtained by consensus of the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network Pathology Committee. Spearman correlation, additivity and variance stabilization for regression for exploring the effect of a number of potential confounders, and receiver operating characteristic analyses were performed. Results: Liver MR imaging–PDFF was systematically higher, with higher histologic steatosis grade (P < .001), and was significantly correlated with histologic steatosis grade (? = 0.69, P < .001). The correlation was not confounded by age, sex, lobular inflammation, hepatocellular ballooning, NASH diagnosis, fibrosis, or magnetic field strength (P = .65). Area under the receiver operating characteristic curves was 0.989 (95% confidence interval: 0.968, 1.000) for distinguishing patients with steatosis grade 0 (n = 5) from those with grade 1 or higher (n = 72), 0.825 (95% confidence interval: 0.734, 0.915) to distinguish those with grade 1 or lower (n = 31) from those with grade 2 or higher (n = 46), and 0.893 (95% confidence interval: 0.809, 0.977) to distinguish those with grade 2 or lower (n = 58) from those with grade 3 (n = 19). Conclusion: MR imaging–PDFF showed promise for assessment of hepatic steatosis grade in patients with NAFLD. For validation, further studies with larger sample sizes are needed. © RSNA, 2013 PMID:23382291

Tang, An; Tan, Justin; Sun, Mark; Hamilton, Gavin; Bydder, Mark; Wolfson, Tanya; Gamst, Anthony C.; Middleton, Michael; Brunt, Elizabeth M.; Loomba, Rohit; Lavine, Joel E.; Schwimmer, Jeffrey B.

2013-01-01

73

White Matter Disease Induced by High-Dose Chemotherapy: Longitudinal Study with MR Imaging and Proton Spectroscopy  

Microsoft Academic Search

PURPOSE: The purpose of this study was to determine the time course for development of white matter changes induced by high-dose chemotherapy. METHODS: Eight patients with advanced breast cancer were entered into a prospective, longitudinal trial that included examination by MR imaging and proton MR spectroscopy before chemotherapy and through 12 months after treatment with carmustine, cyclophospha- mide, and cisplatin,

Mark S. Brown; Salomon M. Stemmer; Jack H. Simon; John C. Stears; Roy B. Jones; Pablo J. Cagnoni; Jeanelle L. Sheeder

74

Deformable motion reconstruction for scanned proton beam therapy using on-line x-ray imaging  

NASA Astrophysics Data System (ADS)

Organ motion is a major problem for any dynamic radiotherapy delivery technique, and is particularly so for spot scanned proton therapy. On the other hand, the use of narrow, magnetically deflected proton pencil beams is potentially an ideal delivery technique for tracking tumour motion on-line. At PSI, our new Gantry is equipped with a Beams Eye View (BEV) imaging system which will be able to acquire 2D x-ray images in fluoroscopy mode during treatment delivery. However, besides precisely tracking motion from BEVs, it is also essential to obtain information on the 3D motion vector throughout the whole region of interest, and any sparsely acquired surrogate motion is generally not sufficient to describe the deformable behaviour of the whole volume in three dimensions. In this study, we propose a method by which 3D deformable motions can be estimated from surrogate motions obtained using this monoscopic imaging system. The method assumes that example motions over a number of breathing cycles can be acquired before treatment for each patient using 4DMRI. In this study, for each of 11 different subjects, 100 continuous breathing cycles have been extracted from extended 4DMRI studies in the liver and then subject specific motion models have been built using principle component analysis (PCA). To simulate treatment conditions, a different set of 30 continuous breathing cycles from the same subjects have then been used to generate a set of simulated 4DCT data sets (so-called 4DCT(MRI) data sets), from which time-resolved digitally reconstructed radiographs (DRRs) were calculated using the BEV geometry for three treatment fields respectively. From these DRRs, surrogate motions from fiducial markers or the diaphragm have been used as a predictor to estimate 3D motions in the liver region for each subject. The prediction results have been directly compared to the ‘ground truth’ motions extracted from the same 30 breath cycles of the originating 4DMRI data set. Averaged over all 11 subjects, and for three field directions, for 99% of predicted positions, median (max) error magnitudes of better than 2.63(5.67) mm can be achieved when fiducial markers was chosen as predictor. Furthermore, three single fields, 4D dose calculations have been performed as a verification tool to evaluate the prediction performance of such a model in the context of scanned proton beam therapy. These show a high similarity between plans considering either PCA predicted motion or ground truth motion, where absolute dose differences of more than 5% (Vdosediff = 5%) occur for the worst field scenarios in only 3.61% (median) or 15.13% (max) of dose calculation points in the irradiated volume. The magnitude of these dose differences were insignificantly dependent on whether surrogate motions were tracked by monoscopic or stereoscopic imaging systems, or whether fiducial markers or diaphragm were chosen as surrogate. This study has demonstrated that on-line deformable motion reconstruction from sparse surrogate motions is feasible, even when using only a monoscopic imaging system. In addition, it has also been found that diaphragm motion can be considered as a good predictor for respiratory deformable liver motion prediction, implying that fiducial markers might not be compulsory if used in conjunction with a patient specific PCA based model.

Zhang, Ye; Knopf, A.; Tanner, C.; Boye, D.; Lomax, A. J.

2013-12-01

75

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

SciTech Connect

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 Region Aquitaine) accelerator at the Centre d'Etudes Nucleaires 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.; Denis-Petit, D.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Aleonard, M. M. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, Universite de Bordeaux, UMR 5797 CNRS/IN2P3, Gradignan 33175 (France); Comet, M. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, Universite de Bordeaux, UMR 5797 CNRS/IN2P3, Gradignan 33175 (France); CEA, DAM, DIF, F-91297 Arpajon (France)

2013-01-15

76

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

77

Characterization of Lung Cancer by Amide Proton Transfer (APT) Imaging: An In-Vivo Study in an Orthotopic Mouse Model  

PubMed Central

Amide proton transfer (APT) imaging is one of the chemical exchange saturation transfer (CEST) imaging methods which images the exchange between protons of free tissue water and the amide groups (?NH) of endogenous mobile proteins and peptides. Previous work suggested the ability of APT imaging for characterization of the tumoral grade in the brain tumor. In this study, we tested the feasibility of in-vivo APT imaging of lung tumor and investigated whether the method could differentiate the tumoral types on orthotopic tumor xenografts from two malignant lung cancer cell lines. The results revealed that APT imaging is feasible to quantify lung tumors in the moving lung. The measured APT effect was higher in the tumor which exhibited more active proliferation than the other. The present study demonstrates that APT imaging has the potential to provide a characterization test to differentiate types or grade of lung cancer noninvasively, which may eventually reduce the need invasive needle biopsy or resection for lung cancer. PMID:24143199

Togao, Osamu; Kessinger, Chase W.; Huang, Gang; Soesbe, Todd C.; Sagiyama, Koji; Dimitrov, Ivan; Sherry, A. Dean; Gao, Jinming; Takahashi, Masaya

2013-01-01

78

Imaging an optogenetic pH sensor reveals that protons mediate lateral inhibition in the retina  

PubMed Central

The reciprocal synapse between photoreceptors and horizontal cells (HCs) underlies lateral inhibition and establishes the antagonistic center-surround receptive fields of retinal neurons, to enhance visual contrast. Despite decades of study, the signal mediating negative feedback from HCs to cones has remained controversial because the small, invaginated synaptic cleft has precluded measurement. Using zebrafish retinas, we show that light elicits a change in synaptic proton concentration with the correct magnitude, kinetics and spatial dependence to account for lateral inhibition. Light, which hyperpolarizes HCs, causes synaptic alkalinization, whereas activating an exogenously expressed ligand-gated Na+ channel, which depolarizes HCs, causes synaptic acidification. While acidification was prevented by blocking a proton pump, re-alkalinization was prevented by blocking proton-permeant ion channels, suggesting that distinct mechanisms underlie proton efflux and influx. These findings reveal that protons mediate lateral inhibition in the retina, raising the possibility that protons are unrecognized retrograde messengers elsewhere in the nervous system. PMID:24441679

Wang, Tzu-Ming; Holzhausen, Lars C.; Kramer, Richard H.

2014-01-01

79

Diffusion tensor imaging and proton magnetic resonance spectroscopy in brain tumor: Correlation between structure and metabolism?  

PubMed Central

Proton magnetic resonance spectroscopy and diffusion tensor imaging are non-invasive techniques used to detect metabolites and water diffusion in vivo. Previous studies have confirmed a positive correlation of individual fractional anisotropy values with N-acetylaspartate/creatine and N-acetylaspartate/choline ratios in tumors, edema, and normal white matter. This study divided the brain parenchyma into tumor, peritumoral edema, and normal-appearing white matter according to MRI data, and analyzed the correlation of metabolites with water molecular diffusion. Results demonstrated that in normal-appearing white matter, N-acetylaspartate/creatine ratios were positively correlated with fractional anisotropy values, negatively correlated with radial diffusivities, and positively correlated with maximum eigenvalues. Maximum eigenvalues and radial diffusivities in peritumoral edema showed a negative correlation with choline, N-acetylaspartate, and creatine. Radial diffusivities in tumor demonstrated a negative correlation with choline. These data suggest that the relationship between metabolism and structure is markedly changed from normal white matter to peritumoral edema and tumor. Neural metabolism in the peritumoral edema area decreased with expanding extracellular space. The normal relationship of neural function and microstructure disappeared in the tumor region.

Min, Zhigang; Niu, Chen; Rana, Netra; Ji, Huanmei; Zhang, Ming

2013-01-01

80

Proton echo-planar spectroscopic imaging ofJ-coupled resonances in human brain at 3 and 4 Tesla  

Microsoft Academic Search

In this multicenter study, 2D spatial mapping of J-coupled res- onances at 3T and 4T was performed using short-TE (15 ms) proton echo-planar spectroscopic imaging (PEPSI). Water-sup- pressed (WS) data were acquired in 8.5 min with 1-cm3 spatial resolution from a supraventricular axial slice. Optimized outer volume suppression (OVS) enabled mapping in close proximity to peripheral scalp regions. Constrained spectral

Stefan Posse; Ricardo Otazo; Arvind Caprihan; Juan Bustillo; Hongji Chen; Pierre-Gilles Henry; Malgorzata Marjanska; Charles Gasparovic; Chun Zuo; Vincent Magnotta; Bryon Mueller; Paul Mullins; Perry Renshaw; Kamil Ugurbil; Kelvin O. Lim; Jeffry R. Alger

2007-01-01

81

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

82

Conjugate observations of ENA signals in the high-altitude cusp and proton auroral spot in the low-altitude cusp with IMAGE spacecraft  

NASA Astrophysics Data System (ADS)

On 28 April 2001, significant enhancements of neutral atom signals were detected in the direction of a high-altitude cusp by the Low-Energy Neutral Atom (LENA) imager onboard the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Simultaneously, proton auroral emission was observed in the low-altitude cusp by the Far-Ultraviolet Instrument (FUV) on the IMAGE spacecraft. The temporal variations of their intensities showed a good correlation, suggesting they had a common source. During a brief period, the proton auroral spot moved antisunward and dawnward in conjunction with the motion of the ionospheric footprint of the LENA cusp signal. The Tsyganenko-96 model shows that the possible source location of the LENA cusp signals maps to the FUV spot. Considering the solar wind variations, we have attributed this ``moving proton auroral spot'' to a moving flux tube that was created by transient reconnection on the dayside magnetopause and contained relatively high proton densities.

Suzuki, S.; Taguchi, S.; Hosokawa, K.; Collier, M. R.; Moore, T. E.; Frey, H. U.; Mende, S. B.

2008-07-01

83

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

84

Proton imaging detection of transient electromagnetic fields in laser-plasma interactions (invited)  

Microsoft Academic Search

Due to their particular properties (small source size, low divergence, short duration, large number density), the beams of 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. In particular, the proton beams are a valuable diagnostic tool for the detection of

M. Borghesi; A. Schiavi; D. H. Campbell; M. G. Haines; O. Willi; A. J. MacKinnon; P. Patel; M. Galimberti; L. A. Gizzi

2003-01-01

85

Imaging an optogenetic pH sensor reveals that protons mediate lateral inhibition in the retina.  

PubMed

The reciprocal synapse between photoreceptors and horizontal cells underlies lateral inhibition and establishes the antagonistic center-surround receptive fields of retinal neurons to enhance visual contrast. Despite decades of study, the signal mediating the negative feedback from horizontal cells to cones has remained under debate because the small, invaginated synaptic cleft has precluded measurement. Using zebrafish retinas, we show that light elicits a change in synaptic proton concentration with the correct magnitude, kinetics and spatial dependence to account for lateral inhibition. Light, which hyperpolarizes horizontal cells, causes synaptic alkalinization, whereas activating an exogenously expressed ligand-gated Na(+) channel, which depolarizes horizontal cells, causes synaptic acidification. Whereas acidification was prevented by blocking a proton pump, re-alkalinization was prevented by blocking proton-permeant ion channels, suggesting that distinct mechanisms underlie proton efflux and influx. These findings reveal that protons mediate lateral inhibition in the retina, raising the possibility that protons are unrecognized retrograde messengers elsewhere in the nervous system. PMID:24441679

Wang, Tzu-Ming; Holzhausen, Lars C; Kramer, Richard H

2014-02-01

86

Three-Dimensional Amide Proton Transfer MR Imaging of Gliomas: Initial Experience and Comparison with Gadolinium Enhancement  

PubMed Central

Purpose To investigate the feasibility of a three-dimensional amide-proton-transfer (APT) imaging sequence with gradient- and spin-echo readouts at 3T in patients with high- or low-grade gliomas. Materials and Methods Fourteen patients with newly diagnosed gliomas were recruited. After B0 inhomogeneity correction on a voxel-by-voxel basis, APT-weighted images were reconstructed using a magnetization-transfer-ratio asymmetry at offsets of ±3.5 ppm with respect to the water resonance. Analysis of variance post-hoc tests were used for statistical evaluations, and results were validated with pathology. Results In six patients with gadolinium-enhancing high-grade gliomas, enhancing tumors on the post-contrast T1-weighted images were consistently hyperintense on the APT-weighted images. Increased APT-weighted signal intensity was also clearly visible in two pathologically proven, high-grade gliomas without gadolinium enhancement. The average APT-weighted signal was significantly higher in the lesions than in the contralateral normal-appearing brain tissue (P < 0.001). In six low-grade gliomas, including two with gadolinium enhancement, APT-weighted imaging showed iso-intensity or mild punctate hyperintensity within all the lesions, which was significantly lower than that seen in the high-grade gliomas (P < 0.001). Conclusion The proposed three-dimensional APT imaging sequence can be incorporated into standard brain MRI protocols for patients with malignant gliomas. PMID:23440878

Zhou, Jinyuan; Zhu, He; Lim, Michael; Blair, Lindsay; Quinones-Hinojosa, Alfredo; Messina, Steven A.; Eberhart, Charles G.; Pomper, Martin G.; Laterra, John; Barker, Peter B.; van Zijl, Peter C.M.; Blakeley, Jaishri O.

2013-01-01

87

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

88

Bone Matrix Imaged In Vivo by Water and Fat Suppressed Proton Projection MRI (WASPI) of Animal and Human Subjects  

PubMed Central

Purpose To demonstrate water and fat suppressed proton projection MRI (WASPI) in a clinical scanner to visualize the solid bone matrix in animal and human subjects. Materials and Methods Pig bone specimens and polymer pellets were used to optimize the WASPI method in terms of soft tissue suppression, image resolution, signal to noise ratio (SNR), and scan time on a 3T MRI scanner. The ankles of healthy 2–3 month old live Yorkshire pigs were scanned with the optimized method. The method was also applied to the wrists of six healthy adult human volunteers to demonstrate the feasibility of the WASPI method in human subjects. A transmit/receive coil built with proton-free materials was utilized to produce a strong B1 field. A fast transmit/receive switch was developed to reduce the long receiver dead time that would otherwise obscure the signals. Results Clear 3D WASPI images of pig ankles and human wrists, showing only the solid bone matrix and other tissues with high solid content (e.g., tendons), with a spatial resolution of 1.6 mm in all three dimensions were obtained in as briefly as 18 min. Conclusion WASPI of the solid matrix of bone in humans and animals in vivo is feasible. PMID:20373441

Wu, Yaotang; Hrovat, Mirko I.; Ackerman, Jerome L.; Reese, Timothy G.; Cao, Haihui; Ecklund, Kirsten; Glimcher, Melvin J.

2010-01-01

89

Speckle Reduction in Medical Ultrasound: A Novel Scatterer Density Weighted Nonlinear Diffusion Algorithm Implemented as a Neural-Network Filter  

Microsoft Academic Search

This paper proposes a novel algorithm for speckle reduction in medical ultrasound imaging while preserving the edges with the added advantages of adaptive noise filtering and speed. We propose a nonlinear image diffusion algorithm that incorporates two local parameters of image quality, namely, scatterer density and texture-based contrast in addition to gradient, to weight the nonlinear diffusion process. The scatterer

Ahmed M. Badawi; Muhammad A. Rushdi

2006-01-01

90

Preoperative Proton MR Spectroscopic Imaging of Brain Tumors: Correlation with Histopathologic Analysis of Resection Specimens  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Tumor progression is often difficult to distinguish from nonneoplastic treatment response on the basis of MR images alone. This study correlates me- tabolite levels measured by preoperative MR spectroscopic (MRS) imaging with histologic find- ings of biopsies, obtained during image-guided resections of brain mass lesions, to clarify the potential role of MRS in making this distinction. METHODS:

Chris Dowling; Andrew W. Bollen; Susan M. Noworolski; Michael W. McDermott; Nicholas M. Barbaro; Roland G. Henry; Susan M. Chang; William P. Dillon; Sarah J. Nelson; Daniel B. Vigneron

2001-01-01

91

Use of high-frequency ultrasound imaging to improve delineation of anterior uveal melanoma for proton irradiation  

NASA Astrophysics Data System (ADS)

The aim of this study was to evaluate high-frequency ultrasound imaging (HFUI) as an aid in localizing anterior margins of tumours of the eye for proton therapy. Proton irradiation of ocular melanoma requires an accurate assessment of all tumour margins. The tumour is marked surgically by suturing to the sclera four or five tantalum rings on the borders of the tumour defined by transillumination. In order to evaluate the clinical usefulness of high-frequency ultrasound imaging, four and five rings were surgically placed in a patient with an iris/ciliary body melanoma and in a patient with ciliochoroidal melanoma using transillumination to localize the tumour margins. Subsequently margins were verified by HFUI. In the first patient, the distances between the rings and the limbus were measured using calipers during surgery and were compared with HFUI measurements and measurements from planning software. The distances were comparable within 0.5 mm. In the second patient the treatment was planned in two different ways using EYEPLAN software. In the first scenario the shape of the tumour and its relation to the rings were obtained from the surgeon's mapping, the fundus drawing using a transilluminating point light source, and the HFUI. In the second scenario, the shape of the tumour was deduced from the ring positions only. It was observed that the maximum difference between the tumour edge as seen on high-frequency ultrasound images and the rings was 2.6 mm. The tumour volume was underestimated by 39% when tumour shape was obtained from ring positions only. During the past year we have utilized HFUI in 18 patients having tumours involving the anterior segment of the eye, among which four were treated with proton therapy. In conclusion, we believe that high-frequency ultrasound imaging provides additional information with respect to the location of tumour margins in ciliary body and anterior uveal melanoma. Occult extension of the tumour within the ciliary body or posterior iris may not be appreciated by transillumination alone.

Daftari, Inder; Barash, David; Lin, Shan; O'Brien, Joan

2001-02-01

92

Results from proton damage tests on the Michelson Doppler Imager CCD for SOHO  

NASA Astrophysics Data System (ADS)

Protons from solar flares represent the major threat to the scientific performance of a CCD in the SOHO orbit at L1, decreasing CTE and thus non-uniformly degrading the MTF of the detector. Lattice damage assessment and prediction rely on accurate radiation damage experiments to 'calibrate' numerical simulations and modeling. The energy ranges where TRIM and NIEL represent valid models overlap around a few MeV. Thus, the proton beam from Lockheed PARL's 0.1 to 3 MeV Van de Graaff generator provides a convenient test facility. We present results from an accurate experiment using 2 MeV protons on the MDI detector (LORAL 1024 X 1024 21 micrometers 3P MPP CCD). A premiere feature in the experiment is the achievement of a stable, uniform low fluence and extremely accurate dosimetry at this relatively low energy. Pre- and post-radiation CTE measurements for our specific mode of operation (relatively fast readout rate of 500 kpix/s) is obtained using Fe55 method over a wide temperature range. They reveal somewhat unexpected results. The damage is more severe to parallel CTE than to serial CTE and the former worsens when cooled down to -50 degree(s)C, then improves when cooled further.

Zayer, Igor; Chapman, Ira; Duncan, Dexter W.; Kelly, G. A.; Mitchell, Keith E.

1993-07-01

93

MR imaging and proton spectroscopy of the breast: how to select the images useful to convey the diagnostic message  

Microsoft Academic Search

Purpose  The purpose of this study was to propose a short way to summarise a breast magnetic resonance (MR) examination including a\\u000a precontrast and contrast-enhanced dynamic study and proton spectroscopy (1H-MRS) in order to convey the diagnostic message.\\u000a \\u000a \\u000a \\u000a Materials and methods  At the Department of Radiology of the Policlinico San Donato (University of Milan), breast MR is routinely performed at 1.5\\u000a T

A. Fausto; A. Magaldi; B. Babaei Paskeh; L. Menicagli; E. N. Lupo; F. Sardanelli

2007-01-01

94

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. PMID:22588144

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

2012-01-01

95

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

PubMed

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. PMID:22588144

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

2012-06-01

96

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

NASA Astrophysics Data System (ADS)

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

2012-06-01

97

PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants  

SciTech Connect

The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of the detector itself. In addition to PET alone, PET/CT imaging provides accurate information on the position of the imaged object and may assess possible anatomical changes during fractionated radiotherapy in clinical applications.

Parodi, Katia; Paganetti, Harald; Cascio, Ethan; Flanz, Jacob B.; Bonab, Ali A.; Alpert, Nathaniel M.; Lohmann, Kevin; Bortfeld, Thomas [Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114 (United States); Massachusetts General Hospital, Department of Radiology, 55 Fruit Street, Boston, Massachusetts 02114 (United States); Siemens Medical Solutions USA, Molecular Imaging, 810 Innovation Drive, Knoxville, Tennessee 37932-2571 (United States); Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114 (United States)

2007-02-15

98

Chemically induced analgesic nephropathy in the rat monitored by proton-electron double-resonance imaging (PEDRI).  

PubMed

Proton-electron double-resonance imaging (PEDRI) was used to assess renal function by monitoring the flow of the exogenous nitroxide free radical proxyl carboxylic acid (PCA) through normal and injured kidneys in the living rat. Kidney damage was induced by treatment with 2-bromoethylamine (BEA), which provides a well established model for human analgesic nephropathy. PCA clearance rates for liver, abdominal blood vessels, and renal tissues were determined from serial PEDRI images of normal rats (n = 6) and rats treated with BEA (n = 21). Different groups of BEA-treated animals were imaged on day 4 (n = 6), day 6 (n = 6), and day 9 (n = 9) after treatment. In BEA-treated rats, there was an increase in PCA half-life in all tissues studied. This increase was greatest in the kidney tissues and the effect progressed with time after treatment. The effect is probably due to BEA-induced damage to the tubules in the renal cortex and may not be related to the primary lesions in the renal medulla. PMID:9702710

Seimenis, I; Foster, M A; Lurie, D J; Hutchison, J M; Whiting, P H; Payne, S

1998-08-01

99

Normalization of neuronal metabolic dysfunction after surgery for temporal lobe epilepsy. Evidence from proton MR spectroscopic imaging.  

PubMed

Surgery is a safe and effective treatment for patients with temporal lobe epilepsy (TLE) who do not respond adequately to anticonvulsant medication and in whom the seizure generator can be identified and safely removed. Proton MR spectroscopic imaging (MRSI) can image and quantify neuronal damage in patients with TLE based on reduced signals from N-acetylaspartate (NAA), a compound localized exclusively in neurons. We performed proton MRSI in patients with TLE before and after surgical treatment to determine whether NAA or other resonance intensities changed in the temporal lobes of patients with TLE after surgery, and whether these changes correlated with surgical outcome. N-acetylaspartate resonance intensity relative to creatine (NAA/Cr) was abnormally low preoperatively in at least one temporal lobe in all 14 patients examined. It was low ipsilaterally in the patients who became seizure free and bilaterally in those who did not. Postoperatively, it increased to the normal range on the side of surgery in all patients who became seizure free. In the one patient who became seizure free and who had low NAA/Cr in both temporal lobes before surgery, NAA/Cr values in the contralateral, unoperated temporal lobe also increased to the normal range. In contrast, NAA relative intensity ratios did not change in those patients who continued to have seizures after surgery. The creatine resonance intensity (Cr) in the temporal lobes was high, relative to the brainstem, in seven patients preoperatively. After surgery, the Cr remained high in two patients, both of whom continued to have seizures. We conclude that NAA (and Cr) abnormalities in TLE do not result solely from neuronal loss and gliosis but can be reversible after postsurgical control of seizures. This implies that the NAA and Cr abnormalities in patients with TLE, at least in part, are dynamic markers of both local and remote physiologic dysfunction associated with ongoing seizures. PMID:9409340

Cendes, F; Andermann, F; Dubeau, F; Matthews, P M; Arnold, D L

1997-12-01

100

Multi-slice Proton MR Spectroscopy and Diffusion weighted Imaging in Methylmalonic Acidemia: Report of Two Cases and Review of the Literature  

Microsoft Academic Search

Summary: Methylmalonic acidemia is an inborn disorder of amino acid metabolism that commonly presents with neurologic deficits. We present the results of multi-slice proton MR spectroscopy and diffusion-weighted imaging of the brain in two patients with methylmalonic acidemia. The findings consisted of restricted diffusion and elevated lac- tate in the globi pallidi, compatible with acute infarction (patient 1) and elevated

Ba-Chinh Trinh; Elias R. Melhem; Peter B. Barker

101

Proton imaging of hohlraum plasma stagnation in inertial-confinement-fusion experiments This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Contact us My IOPscience #12;IOP PUBLISHING and INTERNATIONAL ATOMIC ENERGY AGENCY NUCLEAR FUSION NuclProton imaging of hohlraum plasma stagnation in inertial-confinement-fusion experiments. Fusion 53 073022 (http://iopscience.iop.org/0029-5515/53/7/073022) Download details: IP Address: 24

102

Conjugate observations of ENA signals in the high-altitude cusp and proton auroral spot in the low-altitude cusp with IMAGE spacecraft  

NASA Astrophysics Data System (ADS)

Dayside proton auroral spots in the ionosphere are frequently observed by the Far Ultraviolet Instrument (FUV) onboard the IMAGE spacecraft. On 28 April 2001 (0500-0630 UT), when the solar wind density was about 10 cm- 3 and IMF was northward except for a few short periods, FUV observed proton auroral spots in the cusp ionosphere. The intensification of the proton auroral spot was simultaneous with ENA signals observed by the Low Energy Neutral Atom (LENA) imager on IMAGE also from the direction of the high-altitude cusp. If the primary source of the LENA cusp signal were the proton injection caused by reconnection, then the LENA signal in the high-altitude cusp and the FUV spot in the low-altitude cusp should have a common source. The magnetic field line tracing with the Tsyganenko-96 model shows that the possible source location of the LENA cusp signal maps on the proton auroral spot, and the temporal variations of both intensities also show a correlation. During the interval of interest a brief period has been identified in which the proton aurora moves toward the pre-noon side and the direction of the LENA cusp signal moves poleward. Considering the solar wind variations for this event, we have interpreted these motions as being due to the detached reconnected flux tubes created by a brief southward tilting of the IMF, and not the shift of the reconnection point which is often invoked for the motion of the FUV spot in the cusp. Detailed characteristics about the correspondence between the LENA signal and the FUV spot are presented, and the field line geometry for the detached reconnected flux tube will be discussed.

Suzuki, S.; Taguchi, S.; Hosokawa, K.; Collier, M. R.; Moore, T. E.; Frey, H. U.; Mende, S. B.

2007-12-01

103

Novel generation of pH indicators for proton magnetic resonance spectroscopic imaging.  

PubMed

We describe the synthesis of 1,omega-di-1H-imidazoles 2 and 3, derived from l-threitol and d-mannitol, respectively, showing suitable magnetic and toxicological properties, as novel extracellular pH indicators for 1H spectroscopic imaging by magnetic resonance methods. PMID:17691761

Soler-Padrós, Jordi; Pérez-Mayoral, Elena; Domínguez, Laura; López-Larrubia, Pilar; Soriano, Elena; Marco-Contelles, José Luis; Cerdan, Sebastian; Ballesteros, Paloma

2007-09-01

104

In vivo proton-electron double-resonance imaging of extracellular tumor pH using an advanced nitroxide probe.  

PubMed

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 (pH(e)). In vivo VRF PEDRI was performed on Met-1 tumor-bearing mice. Compared to normal mammary glands with a neutral mean pH(e) (7.1 ± 0.1), we observed broader pH distribution with acidic mean pH(e) (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. PMID:24372284

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

2014-01-21

105

Simultaneous ion luminescence imaging and spectroscopy of individual aerosol particles with external proton or helium microbeams  

NASA Astrophysics Data System (ADS)

Simultaneous microscopic imaging and spectroscopy of individual aerosol particles were performed with an external microbeam. Visible luminescence induced by the external microbeam was successfully used as a probe to detect organic contaminants in the targets. Combined ion luminescence (IL)/particle-induced X-ray emission (PIXE) analysis of the aerosol targets revealed microscopic chemical and elemental composition distributions under ambient atmospheric conditions. The simple confocal micro-optics for the IL spectroscopy and microscopic imaging were sufficiently sensitive for detecting these molecules at sub-parts per million concentrations and at a wavelength resolution of less than 5 nm. The IL spectra were monitored to prevent severe damage to the samples. Furthermore, our IL system has the advantage that it is simple to add to a conventional micro-PIXE system.

Kada, Wataru; Satoh, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

2014-08-01

106

Brain MR Imaging and Proton MR Spectroscopy in Female Mice with Pyruvate Dehydrogenase Complex Deficiency  

Microsoft Academic Search

Pyruvate dehydrogenase complex (PDC) deficiency is an inborn metabolic disorder that causes neurological abnormalities. In\\u000a this report, a murine model of PDC deficiency was analyzed using histology, magnetic resonance (MR) imaging and MR spectroscopy\\u000a (MRS) and the results compared to PDC-deficient female patients. Histological analysis of brains from PDC-deficient mice revealed\\u000a defects in neuronal cytoarchitecture in grey matter and reduced

Lioudmila Pliss; Richard Mazurchuk; Joseph A. Spernyak; Mulchand S. Patel

2007-01-01

107

Proton: the particle.  

PubMed

The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ?10(80). Protons were created at 10(-6) -1 second after the Big Bang at ?1.37 × 10(10) years beforethe present. Proton life span has been experimentally determined to be ?10(34) years; that is, the age of the universe is 10(-24)th of the minimum life span of a proton. The abundance of the elements is hydrogen, ?74%; helium, ?24%; and heavier atoms, ?2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ?87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W(+), W(-), Z(0), and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ?87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter. PMID:24074929

Suit, Herman

2013-11-01

108

Proton: The Particle  

SciTech Connect

The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ?10{sup 80}. Protons were created at 10{sup ?6} –1 second after the Big Bang at ?1.37 × 10{sup 10} years beforethe present. Proton life span has been experimentally determined to be ?10{sup 34} years; that is, the age of the universe is 10{sup ?24}th of the minimum life span of a proton. The abundance of the elements is hydrogen, ?74%; helium, ?24%; and heavier atoms, ?2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ?87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W{sup +}, W{sup ?}, Z{sup 0}, and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ?87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter.

Suit, Herman

2013-11-01

109

The simulated space proton environment for radiation effects on Space Telescope Imaging Spectrograph (STIS)  

NASA Technical Reports Server (NTRS)

The space telescope imaging spectrograph (STIS) is a second generation instrument planned for the Hubble Space Telescope (HST) which is currently in orbit. Candidate glasses and other transmitting materials are being considered for order sorters, in-flight calibration filters, detector windows, and calibration lamps. The glasses for in-flight calibration filters showed significant drop in UV transmission, but can probably still be used on STIS. The addressed topics include the Hubble radiation environment, simulation of orbital exposure at Harvard Cyclotron Laboratory, measurement of spectral transmission, and comments on individual samples.

Becher, Jacob; Fowler, Walter

1992-01-01

110

Quantitative Mapping of Total Choline in Healthy Human Breast Using Proton Echo Planar Spectroscopic Imaging (PEPSI) at 3 Tesla  

PubMed Central

Purpose To quantitatively measure tCho levels in healthy breasts using Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI). Material and Methods The 2-dimensional mapping of tCho at 3 Tesla across an entire breast slice using PEPSI and a hybrid spectral quantification method based on LCModel fitting and integration of tCho using the fitted spectrum were developed. This method was validated in 19 healthy females and compared with single voxel spectroscopy (SVS) and with PRESS prelocalized conventional Magnetic Resonance Spectroscopic Imaging (MRSI) using identical voxel size (8 cc) and similar scan times (~7 min). Results A tCho peak with a signal to noise ratio larger than 2 was detected in 10 subjects using both PEPSI and SVS. The average tCho concentration in these subjects was 0.45 ± 0.2 mmol/kg using PEPSI and 0.48±0.3 mmol/kg using SVS. Comparable results were obtained in 2 subjects using conventional MRSI. High lipid content in the spectra of 9 tCho negative subjects was associated with spectral line broadening of more than 26 Hz, which made tCho detection impossible. Conventional MRSI with PRESS prelocalization in glandular tissue in two of these subjects yielded tCho concentrations comparable to PEPSI. Conclusion The detection sensitivity of PEPSI is comparable to SVS and conventional PRESS-MRSI. PEPSI can be potentially used in the evaluation of tCho in breast cancer. A tCho threshold concentration value of ~0.7mmol/kg might be used to differentiate between cancerous and healthy (or benign) breast tissues based on this work and previous studies. PMID:22782667

Zhao, Chenguang; Bolan, Patrick J.; Royce, Melanie; Lakkadi, Navneeth; Eberhardt, Steven; Sillerud, Laurel; Lee, Sang-Joon; Posse, Stefan

2012-01-01

111

Reproducibility of Proton MR Spectroscopic Imaging (PEPSI): Comparison of Dyslexic and Normal-Reading Children and Effects of Treatment on Brain Lactate Levels during Language Tasks  

Microsoft Academic Search

BACKGROUND AND PURPOSE: We repeated a proton echo-planar spectroscopic imaging (PEPSI) study to test the hypothesis that children with dyslexia and good readers differ in brain lactate activation during a phonologic judgment task before but not after instructional treatment. METHODS: We measured PEPSI brain lactate activation (TR\\/TE, 4000\\/144; 1.5 T) at two points 1-2 months apart during two language tasks

Todd L. Richards; Virginia W. Berninger; Elizabeth H. Aylward; Anne L. Richards; Jennifer B. Thomson; William E. Nagy; Joanne F. Carlisle; Stephen R. Dager; Robert D. Abbott

112

Monte Carlo patient study on the comparison of prompt gamma and PET imaging for range verification in proton therapy  

NASA Astrophysics Data System (ADS)

The purpose of this work was to compare the clinical adaptation of prompt gamma (PG) imaging and positron emission tomography (PET) as independent tools for non-invasive proton beam range verification and treatment validation. The PG range correlation and its differences with PET have been modeled for the first time in a highly heterogeneous tissue environment, using different field sizes and configurations. Four patients with different tumor locations (head and neck, prostate, spine and abdomen) were chosen to compare the site-specific behaviors of the PG and PET images, using both passive scattered and pencil beam fields. Accurate reconstruction of dose, PG and PET distributions was achieved by using the planning computed tomography (CT) image in a validated GEANT4-based Monte Carlo code capable of modeling the treatment nozzle and patient anatomy in detail. The physical and biological washout phenomenon and decay half-lives for PET activity for the most abundant isotopes such as 11C, 15O, 13N, 30P and 38K were taken into account in the data analysis. The attenuation of the gamma signal after traversing the patient geometry and respective detection efficiencies were estimated for both methods to ensure proper comparison. The projected dose, PG and PET profiles along many lines in the beam direction were analyzed to investigate the correlation consistency across the beam width. For all subjects, the PG method showed on average approximately 10 times higher gamma production rates than the PET method before, and 60 to 80 times higher production after including the washout correction and acquisition time delay. This rate strongly depended on tissue density and elemental composition. For broad passive scattered fields, it was demonstrated that large differences exist between PG and PET signal falloff positions and the correlation with the dose distribution for different lines in the beam direction. These variations also depended on the treatment site and the particular subject. Thus, similar to PET, direct range verification with PG in passive scattering is not easily viable. However, upon development of an optimized 3D PG detector, indirect range verification by comparing measured and simulated PG distributions (currently being explored for the PET method) would be more beneficial because it can avoid the inherent biological challenges of the PET imaging. The improved correlation of PG and PET with dose when using pencil beams was evident. PG imaging was found to be potentially advantageous especially for small tumors in the presence of high tissue heterogeneities. Including the effects of detector acceptance and efficiency may hold PET superior in terms of the amplitude of the detected signal (depending on the future development of PG detection technology), but the ability to perform online measurements and avoid signal disintegration (due to washout) with PG are important factors that can outweigh the benefits of higher detection sensitivity.

Moteabbed, M.; España, S.; Paganetti, H.

2011-02-01

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

Enantioselective protonation  

Microsoft Academic Search

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 for achieving enantioselective protonation have been developed by exploiting various means of enantiocontrol in different

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

2009-01-01

115

Amide proton transfer imaging with improved robustness to magnetic field inhomogeneity and magnetization transfer asymmetry using Saturation with Frequency Alternating RF Irradiation (SAFARI)  

PubMed Central

Amide proton transfer (APT) imaging has shown promise as an indicator of tissue pH and as a marker for brain tumors. Sources of error in APT measurements include direct water saturation, and magnetization transfer (MT) from membranes and macromolecules. These are typically suppressed by post-processing asymmetry analysis. However, this approach is strongly dependent on B0 homogeneity and can introduce additional errors due to intrinsic MT asymmetry, aliphatic proton features opposite the amide peak, and radiation damping-induced asymmetry. Although several methods exist to correct for B0 inhomogeneity, they tremendously increase scan times and do not address errors induced by asymmetry of the z-spectrum. In this paper, a novel saturation scheme - saturation with frequency alternating RF irradiation (SAFARI) - is proposed in combination with a new magnetization transfer ratio (MTR) parameter designed to generate APT images insensitive to direct water saturation and MT, even in the presence of B0 inhomogeneity. The feasibility of the SAFARI technique is demonstrated in phantoms and in the human brain. Experimental results show that SAFARI successfully removes direct water saturation and MT contamination from APT images. It is insensitive to B0 offsets up to 180Hz without using additional B0 correction, thereby dramatically reducing scanning time. PMID:21608029

Scheidegger, Rachel; Vinogradov, Elena; Alsop, David C

2011-01-01

116

Comparison Between In-Beam and Offline Positron Emission Tomography Imaging of Proton and Carbon Ion Therapeutic Irradiation at Synchrotron- and Cyclotron-Based Facilities  

SciTech Connect

Purpose: The benefit of using dedicated in-beam positron emission tomography (PET) detectors in the treatment room instead of commercial tomographs nearby is an open question. This work quantitatively compares the measurable signal for in-beam and offline PET imaging, taking into account realistic acquisition strategies at different ion beam facilities. Both scenarios of pulsed and continuous irradiation from synchrotron and cyclotron accelerators are considered, because of their widespread use in most carbon ion and proton therapy centers. Methods and Materials: A mathematical framework is introduced to compare the time-dependent amount and spatial distribution of decays from irradiation-induced isotope production. The latter is calculated with Monte Carlo techniques for real proton treatments of head-and-neck and paraspinal tumors. Extrapolation to carbon ion irradiation is based on results of previous phantom experiments. Biologic clearance is modeled taking into account available data from previous animal and clinical studies. Results: Ratios between the amount of physical decays available for in-beam and offline detection range from 40% to 60% for cyclotron-based facilities, to 65% to 110% (carbon ions) and 94% to 166% (protons) at synchrotron-based facilities, and increase when including biologic clearance. Spatial distributions of decays during irradiation exhibit better correlation with the dose delivery and reduced influence of biologic processes. Conclusions: In-beam imaging can be advantageous for synchrotron-based facilities, provided that efficient PET systems enabling detection of isotope decays during beam extraction are implemented. For very short (<2 min) irradiation times at cyclotron-based facilities, a few minutes of acquisition time after the end of irradiation are needed for counting statistics, thus affecting patient throughput.

Parodi, Katia [Heidelberg Ion-Beam Therapy Centre, Heidelberg (Germany)], E-mail: Katia.Parodi@med.uni-heidelberg.de; Bortfeld, Thomas [Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Haberer, Thomas [Heidelberg Ion-Beam Therapy Centre, Heidelberg (Germany)

2008-07-01

117

[Evaluation of cerebral metabolism by multi-voxel proton magnetic resonance spectroscopy imaging in chronic unilateral internal carotid artery occlusion].  

PubMed

Proton magnetic resonance spectroscopy(1H-MRS) has less been used to analyze cerebral metabolism in ischemic lesions compared to single photon emission computed tomography or positron emission computed tomography. Recent advances in magnetic resonance imaging apparatus and the related software have made possible obtaining multi-voxel 1H-MRS in a single study. We examined multi-voxel 1H-MRS in patients with unilateral internal carotid artery(ICA) occlusion to study the relationship between cerebral metabolism and cerebral blood flow. Fifteen patients(male 11; female 4, 47-76; average 67.1 year-old) with chronic unilateral ICA occlusion and without any marked infarction were studied. 1H-MRS was obtained using a 1.5 T Siemens Magnetom Vision scanner. Multi-voxel spectra were recorded using a SE-2 D-CSI sequence(TR/TE = 1500/135 ms). The volume of interest was 90 x 90 x 20 mm3, placed axially above the lateral ventricle. The single voxel size was 10 x 10 x 20 mm3. N-acetyl aspartate/creatine ratios(NAA/Cr) were calculated on each voxel and were averaged in view of the cortex and the white matter. The regional cerebral blood flow(CBF) was measured by Xenon-CT method. Eight patients were also examined by acetazolamide challenge to evaluate the cerebrovascular reserve capacity. NAA/Cr ratios in normal subjects were 1.905 +/- 0.090(mean +/- standard deviation) in the cortex and 2.183 +/- 0.258 in the white matter in 40's(n = 6), 2.046 +/- 0.166 in the cortex and 2.039 +/- 0.288 in the white matter in 60's(n = 5). The study revealed 7 patients with normal NAA/Cr ratio and CBF, 5 with reduced NAA/Cr ratio and normal CBF, and 3 with reduced NAA/Cr ratio and CBF in the affected cortex. A low correlation coefficient of 0.46 was noted between NAA/Cr ratio and the cerebrovascular reserve capacity calculated by acetazolamide challenge in the affected cortex. In the range of less than +10%(lower limit) in percentile change of regional CBF after acetazolamide injection, NAA/Cr ratio was distributed between 1.600 and 2.044, which were normal or slightly under the lower limit(mean-2 x standard deviation). Multi-voxel 1H-MRS is useful for the evaluation of cerebral metabolism, because it enables to quantify different chemicals in many fields at one time and to compare its distribution with regional CBF. In patients with unilateral ICA occlusion, NAA/Cr ratio of the affected cortex varies depending on the collateral circulation and the contralateral ICA lesions. The Extracranial-Intracranial Bypass should be considered if the case with unilateral ICA occlusion reveals reduced CBF and normal or slightly decreased NAA/Cr ratio in the affected cortex. PMID:10793417

Takayama, H; Suga, S; Kobayashi, M; Sadanaga, F; Hozumi, A; Kanai, Y; Okamura, M; Mihara, B

2000-04-01

118

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

PubMed

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

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

1997-05-01

119

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. PMID:20428461

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

2010-01-01

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. 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

Three-Dimensional Turbo-Spin-Echo Amide Proton Transfer MR Imaging at 3 Tesla and Its Application to High-Grade Human Brain Tumors  

PubMed Central

Purpose Amide proton transfer (APT) imaging is able to extend the achievable MRI contrast to the protein level. In this study, we demonstrate the feasibility of applying a turbo spin echo (TSE)-based, three-dimensional (3D) APT sequence into routine clinical practice for patients with brain tumors. Procedures Experiments were performed on a Philips 3T MRI scanner using an eight-channel phased-array coil for reception. A fast 3D APT sequence with a TSE acquisition was proposed (saturation power, 2 ?T; saturation time, 500 ms; 8 slices). The gradient echo (GRE)-based field-mapping technique or water-saturation-shift-referencing (WASSR) technique was used to acquire B0 maps to correct for B0-induced artifacts in APT images. The test was performed on a box of homogenous protein solution, four healthy volunteers, and eight patients with high-grade gliomas. Results The experimental data from a homogenous, protein-containing phantom and healthy volunteers show that the sequence produced a uniform contrast across all slices. The average MTRasym(3.5ppm) values with GRE B0-corrected 3D APT imaging and WASSR-corrected 3D APT imaging were both comparable to the values obtained using the undemanding single-slice acquisition. The average APT image intensity was consistently higher in the tumor core than in the peripheral edema and in the contralateral normal-appearing white matter (both P < 0.001). Conclusion 3D APT imaging of brain tumors can be performed in about five minutes at 3T using a routine, commercial eight-channel SENSE coil. PMID:22644987

Zhao, Xuna; Wen, Zhibo; Zhang, Ge; Huang, Fanheng; Lu, Shilong; Wang, Xianlong; Hu, Shuguang; Chen, Min; Zhou, Jinyuan

2012-01-01

123

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

124

Proton radiography  

Microsoft Academic Search

With the nuclear weapons program moving to Science Based Stockpile Stewardship (SBSS), new diagnostic techniques are needed to replace weapons testing. Proton Radiography is being developed within the SBSS program as one such tool. It is analogous to transmission X-ray radiography, but uses protons instead of photons. Proton Radiography has high penetrating power, high detection efficiency, small-scattered background, inherent multi-pulse

G. E. Hogan; K. J. Adams; K. R. Alrick; J. F. Amann; J. G. Boissevain; M. L. Crow; S. B. Cushing; J. C. Eddelman; C. J. Espinoza; T. T. Fife; R. A. Gallegos; J. Gomez; T. J. Gorman; N. T. Gray; V. H. Holmes; S. A. Jaramillo; N. S. P. King; J. N. Knudson; R. K. London; R. P. Lopez; J. B. McClelland; F. E. Merrill; K. B. Morley; C. L. Morris; C. T. Mottershead; F. A. Neri; D. M. Numkena; P. D. Pazuchanics; C. Pillai; R. E. Prael; C. M. Riedel; J. S. Sarracino; A. Saunders; H. L. Stacy; B. E. Takala; H. A. Thiessen; H. E. Tucker; P. L. Walstrom; G. J. Yates; H.-J. Ziock; J. D. Zumbro; E. Ables; M. B. Aufderheide; R. M. Bionta; D. H. Fujino; E. P. Hartouni; H.-S. Park; R. Soltz; D. M. Wright; S. Balzer; P. A. Flores; R. T. Thompson; A. Pendzick; R. Prigl; J. Scaduto; E. T. Schwaner; J. M. O'Donnell

1999-01-01

125

PATIENT STUDY OF IN VIVO VERIFICATION OF BEAM DELIVERY AND RANGE, USING POSITRON EMISSION TOMOGRAPHY AND COMPUTED TOMOGRAPHY IMAGING AFTER PROTON THERAPY  

PubMed Central

Purpose To investigate the feasibility and value of positron emission tomography and computed tomography (PET/CT) for treatment verification after proton radiotherapy. Methods and Materials This study included 9 patients with tumors in the cranial base, spine, orbit, and eye. Total doses of 1.8–3 GyE and 10 GyE (for an ocular melanoma) per fraction were delivered in 1 or 2 fields. Imaging was performed with a commercial PET/CT scanner for 30 min, starting within 20 min after treatment. The same treatment immobilization device was used during imaging for all but 2 patients. Measured PET/CT images were coregistered to the planning CT and compared with the corresponding PET expectation, obtained from CT-based Monte Carlo calculations complemented by functional information. For the ocular case, treatment position was approximately replicated, and spatial correlation was deduced from reference clips visible in both the planning radiographs and imaging CT. Here, the expected PET image was obtained from an analytical model. Results Good spatial correlation and quantitative agreement within 30% were found between the measured and expected activity. For head-and-neck patients, the beam range could be verified with an accuracy of 1–2 mm in well-coregistered bony structures. Low spine and eye sites indicated the need for better fixation and coregistration methods. An analysis of activity decay revealed as tissue-effective half-lives of 800–1,150 s. Conclusions This study demonstrates the feasibility of postradiation PET/CT for in vivo treatment verification. It also indicates some technological and methodological improvements needed for optimal clinical application. PMID:17544003

Parodi, Katia; Paganetti, Harald; Shih, Helen A.; Michaud, Susan; Loeffler, Jay S.; Delaney, Thomas F.; Liebsch, Norbert J.; Munzenrider, John E.; Fischman, Alan J.; Knopf, Antje; Bortfeld, Thomas

2007-01-01

126

Patient Study of In Vivo Verification of Beam Delivery and Range, Using Positron Emission Tomography and Computed Tomography Imaging After Proton Therapy  

SciTech Connect

Purpose: To investigate the feasibility and value of positron emission tomography and computed tomography (PET/CT) for treatment verification after proton radiotherapy. Methods and Materials: This study included 9 patients with tumors in the cranial base, spine, orbit, and eye. Total doses of 1.8-3 GyE and 10 GyE (for an ocular melanoma) per fraction were delivered in 1 or 2 fields. Imaging was performed with a commercial PET/CT scanner for 30 min, starting within 20 min after treatment. The same treatment immobilization device was used during imaging for all but 2 patients. Measured PET/CT images were coregistered to the planning CT and compared with the corresponding PET expectation, obtained from CT-based Monte Carlo calculations complemented by functional information. For the ocular case, treatment position was approximately replicated, and spatial correlation was deduced from reference clips visible in both the planning radiographs and imaging CT. Here, the expected PET image was obtained from an analytical model. Results: Good spatial correlation and quantitative agreement within 30% were found between the measured and expected activity. For head-and-neck patients, the beam range could be verified with an accuracy of 1-2 mm in well-coregistered bony structures. Low spine and eye sites indicated the need for better fixation and coregistration methods. An analysis of activity decay revealed as tissue-effective half-lives of 800-1,150 s. Conclusions: This study demonstrates the feasibility of postradiation PET/CT for in vivo treatment verification. It also indicates some technological and methodological improvements needed for optimal clinical application.

Parodi, Katia [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States)]. E-mail: Katia.Parodi@med.uni-heidelberg.de; Paganetti, Harald [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Shih, Helen A. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Michaud, Susan [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Loeffler, Jay S. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); DeLaney, Thomas F. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Liebsch, Norbert J. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Munzenrider, John E. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Fischman, Alan J. [Division of Nuclear Medicine, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Knopf, Antje [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Bortfeld, Thomas [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States)

2007-07-01

127

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

128

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

129

Proton Transport  

NASA Technical Reports Server (NTRS)

The transport of protons across membranes is an essential process for both bioenergetics of modern cells and the origins of cellular life. All living systems make use of proton gradients across cell walls to convert environmental energy into a high-energy chemical compound, adenosine triphosphate (ATP), synthesized from adenosine diphosphate. ATP, in turn, is used as a source of energy to drive many cellular reactions. The ubiquity of this process in biology suggests that even the earliest cellular systems were relying on proton gradient for harvesting environmental energy needed to support their survival and growth. In contemporary cells, proton transfer is assisted by large, complex proteins embedded in membranes. The issue addressed in this Study was: how the same process can be accomplished with the aid of similar but much simpler molecules that could have existed in the protobiological milieu? The model system used in the study contained a bilayer membrane made of phospholipid, dimyristoylphosphatidylcholine (DMPC) which is a good model of the biological membranes forming cellular boundaries. Both sides of the bilayer were surrounded by water which simulated the environment inside and outside the cell. Embedded in the membrane was a fragment of the Influenza-A M$_2$ protein and enough sodium counterions to maintain system neutrality. This protein has been shown to exhibit remarkably high rates of proton transport and, therefore, is an excellent model to study the formation of proton gradients across membranes. The Influenza M$_2$ protein is 97 amino acids in length, but a fragment 25 amino acids long. which contains a transmembrane domain of 19 amino acids flanked by three amino acids on each side. is sufficient to transport protons. Four identical protein fragments, each folded into a helix, aggregate to form small channels spanning the membrane. Protons are conducted through a narrow pore in the middle of the channel in response to applied voltage. This channel is large enough to contain water molecules. and is normally filled with water. In analogy to the mechanism of proton transfer in some other channels, it has been postulated that protons are translocated along the network of water molecules filling the pore of the channel. This mechanism, however, must involve an additional important step because the channel contains four histidine amino acid residues, one from each of the helices, which are sufficiently large to occlude the pore and interrupt the water network. The histidine residues ensure channel selectivity by blocking transport of small ions, such as sodium or potassium. They have been also implicated in gating protons due to the ability of each histidine to become positively charged by accepting an additional proton. Two mechanisms of gating have been proposed. In one mechanism, all four histidines acquire an additional proton and, due to repulsion between their positive charges, move away from one another, thus opening the channel. The alternative mechanism relies of the ability of protons to move between different atoms in a molecule (tautomerization). Thus, a proton is captured on one side of the gate while another proton is released from the opposite side, and the molecule returns to the initial state through tautomerization. The simulations were designed to test these two mechanisms. Large-scale, atomic-level molecular dynamics simulations of the channel with the histidine residues in different protonation states revealed that all intermediate states of the system involved in the tautomerization mechanism are structurally stable and the arrangement of water molecules in the channel is conducive to the proton transport. In contrast, in the four-protonated state, postulated to exist in the gate-opening mechanism, the electrostatic repulsion between the histidine residues appears to be so large that the channel loses its structural integrity and one helix moves away from the remaining three. Additional information is contained within the original extended abstract.

Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

2001-01-01

130

Characterization of Lung Cancer by Amide Proton Transfer (APT) Imaging: An In-Vivo Study in an  

E-print Network

. In addition, cumulative radiation exposure resulting from repeated use of CT increases the risk of malignancy-resolution CT (HRCT) is the standard imaging technique for assessing lung cancer [2] [3]. It provides excellent (CT) have enabled larger volume coverage with higher resolution and lower noise, and currently high

Gao, Jinming

131

Metabolic Counterpart of Decreased Apparent Diffusion Coefficient During Hyperacute Ischemic Stroke A Brain Proton Magnetic Resonance Spectroscopic Imaging Study  

Microsoft Academic Search

Background and Purpose—Recent studies have shown that the brain ischemic area defined by the map of decreased apparent diffusion coefficient (ADC) obtained by diffusion-weighted imaging (DWI) during the first hours of ischemic stroke includes a significant part of ischemic penumbra. We hypothesize that the misjudgment of the final infarct size by ADC mapping may be related to a restricted ability

F. Nicoli; Y. Lefur; B. Denis; J. P. Ranjeva; S. Confort-Gouny; P. J. Cozzone

2010-01-01

132

Proton Therapy  

MedlinePLUS

Donate Donate One Time Monthly Event Tribute For brain tumor information and support Call: 800-886-ABTA (2282) ... Donate Now Menu Treatment & Care Continuum of Care Brain Tumor Treatments Steroids Surgery Chemotherapy Radiation Stereotactic Radiosurgery Proton ...

133

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

134

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. PMID:23536796

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

2013-01-01

135

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

E-print Network

alignment and verification procedures for proton beam radiation therapy. The quality of the image, both radiation therapy for cancer patients, research into new imaging methods that can improve the accuracy of proton range estimates in radiation therapy planning have become a high priority. Protons

California at Santa Cruz, University of

136

Proton-Proton Scattering at 240 Mev  

Microsoft Academic Search

Differential proton-proton scattering cross sections have been measured at six angles in the range from 27 to 90 degrees center of mass. The internal undeflected cyclotron beam was used with a hydrocarbon target. Proton-proton scattering was differentiated by detecting the emitted proton pair with its definite angle between particles in coincidence with two scintillation counters. Scintillator dimensions determined the solid

C. L. Oxley; R. D. Schamberger

1952-01-01

137

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

Microsoft Academic Search

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

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

2011-01-01

138

Influence of permittivity and electrical conductivity on image pattern of MRI.  

PubMed

In proton density-weighted (PDW) MR imaging, the patterns of signal intensity vary depending on the imaged material, and change with the flip angle (FA) applied to the imaged material. The correlation between the pre-determined FA and the actual FA applied to imaged objects was investigated using 4 types of phantoms having different dielectric properties. PDW images were acquired using the spin-echo (SE) method and different pre-determined FA. Dependency of the signal intensity distribution in the phantom on the pre-determined FA differed among phantoms: patterns for water and 0.402 w/w% saline solution phantoms changed with the pre-determined FA, whereas those for olive oil and 4.02 w/w% saline solution phantoms were barely affected by the pre-determined FA. Causes of these phenomena were considered to be the differences between the pre-determined FA and the actual FA among the phantoms; differences were also influenced by the positioning of the phantom. Our study showed that the actual FA in the phantom is greater than the pre-determined FA in high permittivity media, whereas it is reduced by an increased conductivity of the media. PMID:23694908

Harimoto, Takashi; Ohno, Seiichiro; Hattori, Kengo; Hirosue, Miyuki; Miyai, Masahiro; Shibuya, Koichi; Kuroda, Masahiro; Kanazawa, Susumu; Kato, Hirokazu

2013-01-01

139

Nonidentical protons  

NASA Astrophysics Data System (ADS)

We have calculated the proton charge radius by assuming that the real proton radius is not unique and the radii are randomly distributed in a certain range. This is performed by averaging the elastic electron-proton differential cross section over the form factor cutoff. By using a dipole form factor and fitting the middle value of the cutoff to the low-Q2 Mainz data, we found the lowest ?2/N for a cutoff ?=0.8203±0.0003 GeV, which corresponds to a proton charge radius rE=0.8333±0.0004 fm. The result is compatible with the recent precision measurement of the Lamb shift in muonic hydrogen as well as recent calculations using more sophisticated techniques. Our result indicates that the relative variation of the form factor cutoff should be around 21.5%. Based on this result we have investigated effects of the nucleon radius variation on the symmetric nuclear matter (SNM) and the neutron star matter (NSM) by considering the excluded volume effect in our calculation. The mass-radius relation of a neutron star is found to be sensitive to this variation. The nucleon effective mass in the SNM and the equation of state of both the SNM and the NSM exhibit a similar sensitivity.

Mart, T.; Sulaksono, A.

2013-02-01

140

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

141

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

142

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

PubMed

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. PMID:21983482

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

2011-11-01

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

Correlation of Histological Examination of Meniscus with MR Images: Focused on High Signal Intensity of the Meniscus Not Caused by Definite Meniscal Tear and Impact on MR Diagnosis of Tears  

PubMed Central

Objective To document the causes of high signal intensity of the meniscus which is not caused by definite meniscal tears on MR imaging, through correlation with histological examination. Materials and Methods For the correlation between the MR image and histology, we obtained prospectively 31 meniscal specimens from 21 patients. Proton density-weighted turbo spin-echo MR images were used. Minimal tear, thinning of the lamellar layer, degeneration of the central layer, and radial tie fibers were detected upon histological examination, and were correlated with the corresponding MR images. Results Minimal tear of the lamellar layer was seen in 60 zones out of 100 slides. On MR images, 29 (48.3%) of these 60 zones had high signal intensity. Thinning of the lamellar layer was seen in 24 zones, with 7 (29.2%) having high signal intensity. 57 central zones showed degenerative change in the central layer and high signal intensity on all corresponding MR images. Radial tie fibers in the central layer appeared as high signal intensity areas. Conclusion Minimal tear and thinning of the lamellar layer, degeneration and radial tie fibers of the central layer of the meniscus cause high signal intensity on MR images. PMID:24265570

Li, Chun Ai; Kim, Min Ki; Kim, In Hwan; Lee, Ju Hong; Jang, Kyu Yun

2013-01-01

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. PMID:22542276

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

2013-01-01

147

Electron and Proton Auroral Dynamics  

NASA Technical Reports Server (NTRS)

Data from the Wide-band Imaging Camera (WIC) sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha were analyzed during a high altitude orbit segment of the IMAGE spacecraft. This segment began during the expansive phase of a substorm. The aurora changed into a double oval configuration, consisting of a set of discrete pole-ward forms and a separate diffuse auroral oval equatorwards, Although IMF Bz was strongly southward considerable activity could be seen poleward of the discrete auroras in the region that was considered to be the polar cap. The SI12 Doppler shifted Lyman alpha signature of precipitating protons show that the proton aurora is on the equatorward side of the diffuse aurora. In the following several hours the IMF Bz field changed signed. Although the general character of the proton and electron aurora did not change, the dayside aurora moved equatorward when the Bz was negative and more bright aurora was seen in the central polar cap during periods of positive Bz.

Mende, S. B.; Frey, H. U.; Gerard, J. C.; Hubert, B.; Fuselier, S.; Spann, J. F., Jr.; Gladstone, R.; Burch, J. L.; Rose, M. Franklin (Technical Monitor)

2000-01-01

148

Black-Blood Multicontrast Imaging of Carotid Arteries with DANTE-prepared 2D and 3D MR Imaging.  

PubMed

Purpose To prospectively compare the black-blood ( BB black blood ) imaging efficiency of a delay alternating with nutation for tailored excitation ( DANTE delay alternating with nutation for tailored excitation ) preparation module with conventional double inversion-recovery ( DIR double inversion recovery ) and motion-sensitive driven equilibrium ( MSDE motion-sensitive driven equilibrium ) preparation modules and to introduce a new three-dimensional ( 3D three-dimensional ) T1-weighted magnetic resonance (MR) imaging sequence. Materials and Methods Carotid artery wall imaging was performed in 10 healthy volunteers and 15 patients in accordance with an institutional review board-approved protocol. Two-dimensional ( 2D two-dimensional ) turbo spin-echo ( TSE turbo spin echo ) and 3D three-dimensional fast low-angle shot ( FLASH fast low-angle shot ) sequences served as readout modules. DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted 2D two-dimensional TSE turbo spin echo images, as well as T1-weighted 3D three-dimensional DANTE delay alternating with nutation for tailored excitation -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional DASH DANTE-prepared FLASH ) images, were acquired in the region of the carotid artery bifurcation. For comparison, 2D two-dimensional DIR double inversion recovery -prepared, 2D two-dimensional MSDE motion-sensitive driven equilibrium -prepared multicontrast TSE turbo spin echo , and 3D three-dimensional MSDE motion-sensitive driven equilibrium -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional MERGE MSDE-prepared FLASH ) MR images were also acquired. The effective contrast-to-noise ratio ( CNReff effective contrast-to-noise ratio ) per unit time was calculated for all sequences. Paired t tests were performed to test within-group differences in vessel wall CNReff effective contrast-to-noise ratio . Results The CNReff effective contrast-to-noise ratio of DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted sequences was 27.3, 14.7, and 25.7 mm(-1)min(-1/2), respectively; this represented an improvement of approximately 25%-100% (P < .05) when compared with the CNReff effective contrast-to-noise ratio attained with existing methods. The 3D three-dimensional DASH DANTE-prepared FLASH technique proved to be a fast (<2 seconds per section) and high-spatial-resolution (0.6 mm isotropic) BB black blood technique with higher (75%-100% improvement, P < .001) signal-to-noise ratio efficiency than the 3D three-dimensional MERGE MSDE-prepared FLASH technique. Conclusion The DANTE delay alternating with nutation for tailored excitation -prepared multicontrast 2D two-dimensional BB black blood technique is a promising new tool for MR imaging of carotid artery walls. Additionally, the 3D three-dimensional DASH DANTE-prepared FLASH sequence enables 3D three-dimensional high-spatial-resolution fast T1-weighted imaging of carotid artery walls. ©RSNA, 2014 Online supplemental material is available for this article . PMID:24918958

Li, Linqing; Chai, Joshua T; Biasiolli, Luca; Robson, Matthew D; Choudhury, Robin P; Handa, Ashok I; Near, Jamie; Jezzard, Peter

2014-11-01

149

Physics in Medicine: Building a Proton Therapy Facility at the Midwest Proton Radiotherapy Institute  

NASA Astrophysics Data System (ADS)

The Midwest Proton Radiotherapy Institute, located in Bloomington, Indiana, makes use of the latest imaging and radiation technology as it is about to come on line as the third proton therapy treatment facility in the U.S. Protons, unlike conventional radiation, deposit most of their energy at a particular depth in tissue, dependent on their incident energy. Thus the majority of radiation is absorbed by the targeted tumor, rather than the healthy surrounding tissue. I will report on my work assisting in the design of the dose delivery system, design and installation of safety systems, and commissioning the proton beam to ensure that treatment plans match up to physical dose depositions.

Skeen, Michael M.

2003-10-01

150

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

151

Proton aurora related to intervals of pulsations of diminishing periods  

NASA Astrophysics Data System (ADS)

Geomagnetic pulsations in the Pc1 frequency range are believed to be an indicator of electromagnetic ion cyclotron waves arriving from the equatorial magnetosphere, where the waves are generated because of a cyclotron instability of the anisotropic distribution of ring current ions. Proton precipitation produced by the cyclotron instability can be responsible for proton aurora. Indeed, the relationship between some types of proton aurora (proton spots and proton flashes) and pulsations in the Pc1 range (quasi-monochromatic Pc1 and Pc1 bursts) has already been found. The aim of this study is to find the proton aurora pattern, which relates to the kind of geomagnetic pulsations in the Pc1 range called intervals of pulsation of diminishing periods (IPDP). This is done on the basis of 2 year observations of geomagnetic pulsations at the Finnish meridional network of search coil magnetometers and proton aurora from the IMAGE spacecraft. We found that during IPDP the proton arcs appear equatorward of the proton oval at the meridian of the ground magnetometers. The maximum intensity of the pulsations is observed at the ground station, which is closest to the proton arc. The proton arcs tend to appear at lower latitudes at later magnetic local times (MLTs). This agrees with the facts that the IPDP occurrence exhibits a similar behavior and that the IPDP end frequency tends to increase with increasing MLT. In addition, data from geosynchronous spacecraft showed that IPDP occur when clouds of energy-dispersed energetic protons pass through the meridian of the ground magnetometers. The spatial-temporal correlation of IPDP with proton aurora arcs confirms the expectation that the proton arcs, like the proton spots and flashes, are the ionospheric image of the region where the ion cyclotron instability develops in the equatorial magnetosphere. In the case of IPDP the instability develops when drifting proton clouds resulting from particle injections in the night sector contact the plasmaspheric plume onto which the proton arcs map.

Yahnin, A. G.; Yahnina, T. A.; Frey, H. U.; Bösinger, T.; Manninen, J.

2009-12-01

152

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

153

Proton Therapy for Thoracoabdominal Tumors  

NASA Astrophysics Data System (ADS)

In advanced-stage disease of certain thoracoabdominal tumors, proton therapy (PT) with concurrent chemotherapy may be an option to reduce side effects. Several technological developments, including a respiratory gating system and implantation of fiducial markers for image guided radiation therapy (IGRT), are necessary for the treatment in thoracoabdominal tumors. In this chapter, the role of PT for tumors of the lung, the esophagus, and liver are discussed.

Sakurai, Hideyuki; Okumura, Toshiyuki; Sugahara, Shinji; Nakayama, Hidetsugu; Tokuuye, Koichi

154

Persistent global proton aurora caused by high solar wind dynamic pressure  

E-print Network

Persistent global proton aurora caused by high solar wind dynamic pressure K. M. Laundal1 and N] Global images of the proton aurora taken with the SI-12 camera onboard the IMAGE satellite reveal a very direct relationship between the solar wind dynamic pressure and the intensity of the global proton aurora

Bergen, Universitetet i

155

Elastic proton-proton scattering at RHIC  

SciTech Connect

Here we describe elastic proton+proton (p+p) scattering measurements at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run. We present preliminary results of single and double spin asymmetries.

Yip, K.

2011-09-03

156

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

157

Treatment planning in proton therapy  

NASA Astrophysics Data System (ADS)

Radiotherapy treatment planning is a procedure that, using radiation beam and patient's anatomy models as input data, produces as output the machine instructions to deliver the treatment and the expected dose distribution in the patient. Now that most proton therapy centers are moving from double scattered proton beams to active delivery systems such as pencil beam scanning (PBS), there is a need for treatment planning tools that could generate safe and effective dose distribution by taking full benefit of the potential of PBS degrees of freedom, and by avoiding the risks associated to this modality. The paper provides an overview of the current status of proton treatment planning techniques, from the creation of a patient model via imaging, to dose calculation, to the optimization of plans using intensity modulated proton therapy (IMPT). The issue of plan sensitivity to input data ("plan robustness") is emphasized and current approaches to robust optimization are presented. Finally, current developments in "adaptive planning" and in the plan design for moving organs are shortly discussed.

Schwarz, M.

2011-07-01

158

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

159

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

160

Imaging.  

PubMed

Imaging of the musculoskeletal system includes many modalities and is an area that is changing rapidly. Selection of the most accurate techniques and avoidance of duplication are vital to both good patient care and cost containment. PMID:3466135

Wilkinson, R

1986-12-01

161

Amide proton transfer-weighted imaging of the head and neck at 3?T: a feasibility study on healthy human subjects and patients with head and neck cancer.  

PubMed

The aim of this study was to explore the feasibility and repeatability of amide proton transfer-weighted (APTw) MRI for the head and neck on clinical MRI scanners. Six healthy volunteers and four patients with head and neck tumors underwent APTw MRI scanning at 3?T. The APTw signal was quantified by the asymmetric magnetization transfer ratio (MTRasym) at 3.5?ppm. Z spectra of normal tissues in the head and neck (masseter muscle, parotid glands, submandibular glands and thyroid glands) were analyzed in healthy volunteers. Inter-scan repeatability of APTw MRI was evaluated in six healthy volunteers. Z spectra of patients with head and neck tumors were produced and APTw signals in these tumors were analyzed. APTw MRI scanning was successful for all 10 subjects. The parotid glands showed the highest APTw signal (~7.6% average), whereas the APTw signals in other tissues were relatively moderate. The repeatability of APTw signals from the masseter muscle, parotid gland, submandibular gland and thyroid gland of healthy volunteers was established. Four head and neck tumors showed positive mean APTw ranging from 1.2% to 3.2%, distinguishable from surrounding normal tissues. APTw MRI was feasible for use in the head and neck regions at 3?T. The preliminary results on patients with head and neck tumors indicated the potential of APTw MRI for clinical applications. PMID:25137521

Yuan, Jing; Chen, Shuzhong; King, Ann D; Zhou, Jinyuan; Bhatia, Kunwar S; Zhang, Qinwei; Yeung, David Ka Wei; Wei, Juan; Mok, Greta Seng Peng; Wang, Yi-Xiang

2014-10-01

162

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

163

Sliding window dual gradient echo (SW-dGRE): T1 and proton resonance frequency (PRF) calibration for temperature imaging in polyacrylamide gel  

NASA Astrophysics Data System (ADS)

The aim of the work is to evaluate a magnetic resonance imaging (MRI) thermometry sequence suitable for targeting of focused ultrasound (FUS) when used in vascular occlusion studies. A sliding window dual gradient echo (SW-dGRE) sequence was used. This sequence has the capability of monitoring both T1 relaxation and phase changes, which vary with temperature. Preliminary work involved quantification of the changes in T1 relaxation time with temperature and obtaining the PRF shift coefficient in polyacrylamide gel as it underwent an exothermic reaction during polymerization (avoiding the use of an external heat source). Temperature changes were visualized using thermal maps acquired with the sequence. For FUS guidance a thermal imaging technique is required with a temporal resolution <5 s, a spatial resolution of ~1 mm and a temperature resolution of ~5 °C. The sequence was optimized to improve the CNR (contrast to noise ratio) and SNR (signal to noise ratio) in the phase and magnitude images respectively. The PRF coefficient obtained for the polyacrylamide gel was -9.98 +/- 0.24 ppb °C-1, whilst DeltaT1 and temperature change were related by a proportionality factor, the T1 temperature coefficient, of 102.3 +/- 2.9 ms °C-1. The sequence produces an image at every 1.4 s interval. In both magnitude and phase data, the in-plane resolution is +/-1.2 mm and the temperature resolution is ~2 °C. The advantage of this sequence is that the temperature obtained from the magnitude data can be confirmed independently using the phase data and vice versa. Thus the sequence can essentially be crosschecked.

Ong, J. T.; d'Arcy, J. A.; Collins, D. J.; Rivens, I. H.; ter Haar, G. R.; Leach, M. O.

2003-07-01

164

New heavy proton radioactivities  

SciTech Connect

The new proton radioactivities {sup 165,166,167}Ir, {sup 171}Au, and {sup 185}Bi have been observed, extending our knowledge of proton radioactivity up to and beyond the Z=82 closed shell. For Z=77 and 79, the transitions can be explained using simple shell-model arguments. The case of {sup 185}Bi represents the first example of proton radioactivity from an intruder state.

Davids, C.N. [Argonne National Lab., IL (United States); Woods, P.J. [Edinburgh Univ. (United Kingdom); Batchelder, J.C. [Louisiana State Univ., Baton Rouge, LA (United States)] [and others

1995-08-01

165

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

E-print Network

The jet energy scale (JES) 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 inverse pb. Jets are reconstructed with the anti-kt 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 pt > 20 GeV and pseudorapidities eta 50 GeV after a dedicated correction for this effect. The JES 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 pt, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pt jets recoiling against a high-pt jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, p...

Aad, Georges; Abdallah, Jalal; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; Abramowicz, Halina; Abreu, Henso; Acerbi, Emilio; Acharya, Bobby Samir; Adams, David; Addy, Tetteh; Adelman, Jahred; Aderholz, Michael; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; ? kesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Akiyama, Kunihiro; Alam, Mohammad; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Aliyev, Magsud; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alviggi, Mariagrazia; Amako, Katsuya; Amaral, Pedro; Amelung, Christoph; Ammosov, Vladimir; Amorim, Antonio; Amorós, Gabriel; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Andrieux, Marie-Laure; Anduaga, Xabier; Angerami, Aaron; Anghinolfi, Francis; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoun, Sahar; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Archambault, John-Paul; Arfaoui, Samir; Arguin, Jean-Francois; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnault, Christian; Artamonov, Andrei; Artoni, Giacomo; Arutinov, David; Asai, Shoji; Asfandiyarov, Ruslan; Ask, Stefan; ? sman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astbury, Alan; Astvatsatourov, Anatoli; Atoian, Grigor; Aubert, Bernard; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Austin, Nicholas; Avolio, Giuseppe; Avramidou, Rachel Maria; Axen, David; Ay, Cano; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Bachy, Gerard; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagnaia, Paolo; Bahinipati, Seema; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Mark; Baker, Sarah; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barashkou, Andrei; Barbaro Galtieri, Angela; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Barrillon, Pierre; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Detlef; Bartsch, Valeria; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Battistoni, Giuseppe; Bauer, Florian; Bawa, Harinder Singh; Beare, Brian; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Begel, Michael; Behar Harpaz, Silvia; Behera, Prafulla; Beimforde, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellina, Francesco; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Ben Ami, Sagi; Benary, Odette; Benchekroun, Driss; Benchouk, Chafik; Bendel, Markus; Benekos, Nektarios; Benhammou, Yan; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernardet, Karim; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Berry, Tracey; Bertin, Antonio; Bertinelli, Francesco; Bertolucci, Federico; Besana, Maria Ilaria; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bitenc, Urban; Black, Kevin; Blair, Robert; Blanchard, Jean-Baptiste; Blanchot, Georges; Blazek, Tomas; Blocker, Craig; Blocki, Jacek

2013-01-01

166

Intensified\\/shuttered cooled CCD camera for dynamic proton radiography  

Microsoft Academic Search

An intensified\\/shuttered cooled PC-based CCD camera system was designed and successfully fielded on proton radiography experiments at the Los Alamos National Laboratory ALNSCE facility using 800-MeV protons. The four camera detector system used front-illuminated full-frame CCD arrays fiber optically coupled to either 25-mm diameter planar diode or microchannel plate image intensifiers which provided optical shuttering for time resolved imaging of

George J. Yates; Kevin L. Albright; K. R. Alrick; Robert A. Gallegos; J. Galyardt; Norman T. Gray; Gary E. Hogan; Vanner H. Holmes; Steven A. Jaramillo; Nicholas S. King; Thomas E. McDonald; Kevin B. Morley; Christopher L. Morris; Dustin Numkena; Peter D. Pazuchanics; C. M. Riedel; J. S. Sarracino; Hans-Joachim Ziock; John Zumbro

1998-01-01

167

Proton aurora dynamics in response to the IMF and solar wind variations  

E-print Network

Proton aurora dynamics in response to the IMF and solar wind variations S.-W. Chang,1,2 S. B. Mende; accepted 24 April 2002; published 13 July 2002. [1] On May 23, 2000, proton auroras observed by IMAGE FUV wind parameters. A proton aurora brightened at high latitude poleward from the dayside oval after solar

California at Berkeley, University of

168

Preliminary results of an in-beam PET prototype for proton therapy  

Microsoft Academic Search

Proton therapy can overcome the limitations of conventional radiotherapy due to the more selective energy deposition in depth and to the increased biological effectiveness. Verification of the delivered dose is desirable, but the complete stopping of the protons in patient prevents the application of electronic portal imaging methods that are used in conventional radiotherapy During proton therapy ?+ emitters like

F. Attanasi; N. Belcari; M. Camarda; G. A. P. Cirrone; G. Cuttone; A. Del Guerra; F. Di Rosa; N. Lanconelli; V. Rosso; G. Russo; S. Vecchio

2008-01-01

169

An 800MeV proton radiography facility for dynamic experiments  

Microsoft Academic Search

The capability has successfully been developed at the Los Alamos Nuclear Science Center (LANSCE) to utilize a spatially and temporally prepared 800MeV proton beam to produce proton radiographs. A series of proton bursts are transmitted through a dynamic object and transported, via a unique magnetic lens system, to an image plane. The magnetic lens system permits correcting for the effects

N. S. P. King; E. Ables; Ken Adams; K. R. Alrick; J. F. Amann; Stephen Balzar; P. D. Barnes Jr; M. L. Crow; S. B. Cushing; J. C. Eddleman; T. T. Fife; Paul Flores; D. Fujino; R. A. Gallegos; N. T. Gray; E. P. Hartouni; G. E. Hogan; V. H. Holmes; S. A. Jaramillo; J. N. Knudsson; R. K. London; R. R. Lopez; T. E. McDonald; J. B. McClelland; F. E. Merrill; K. B. Morley; C. L. Morris; F. J. Naivar; E. L. Parker; H. S Park; P. D Pazuchanics; C. Pillai; C. M Riedel; J. S Sarracino; F. E Shelley Jr; H. L Stacy; B. E Takala; Richard Thompson; H. E Tucker; G. J Yates; H.-J Ziock; J. D Zumbro

1999-01-01

170

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

171

Proton Magnetic Resonance Spectroscopic Imaging in Newly Diagnosed Glioblastoma: Predictive Value for the Site of Postradiotherapy Relapse in a Prospective Longitudinal Study  

SciTech Connect

Purpose: To investigate the association between magnetic resonance spectroscopic imaging (MRSI)-defined, metabolically abnormal tumor regions and subsequent sites of relapse in data from patients treated with radiotherapy (RT) in a prospective clinical trial. Methods and Materials: Twenty-three examinations were performed prospectively for 9 patients with newly diagnosed glioblastoma multiforme studied in a Phase I trial combining Tipifarnib and RT. The patients underwent magnetic resonance imaging (MRI) and MRSI before treatment and every 2 months until relapse. The MRSI data were categorized by the choline (Cho)/N-acetyl-aspartate (NAA) ratio (CNR) as a measure of spectroscopic abnormality. CNRs corresponding to T1 and T2 MRI for 1,207 voxels were evaluated before RT and at recurrence. Results: Before treatment, areas of CNR2 (CNR {>=}2) represented 25% of the contrast-enhancing (T1CE) regions and 10% of abnormal T2 regions outside T1CE (HyperT2). The presence of CNR2 was often an early indicator of the site of relapse after therapy. In fact, 75% of the voxels within the T1CE+CNR2 before therapy continued to exhibit CNR2 at relapse, compared with 22% of the voxels within the T1CE with normal CNR (p < 0.05). The location of new contrast enhancement with CNR2 corresponded in 80% of the initial HyperT2+CNR2 vs. 20.7% of the HyperT2 voxels with normal CNR (p < 0.05). Conclusion: Metabolically active regions represented a small percentage of pretreatment MRI abnormalities and were predictive for the site of post-RT relapse. The incorporation of MRSI data in the definition of RT target volumes for selective boosting may be a promising avenue leading to increased local control of glioblastomas.

Laprie, Anne [Department of Radiation Oncology, Institut Claudius Regaud, Toulouse (France); Laboratory of Biophysics and Medical Imaging, Universite Toulouse III Paul Sabatier, Toulouse (France)], E-mail: Laprie.Anne@claudiusregaud.fr; Catalaa, Isabelle [Laboratory of Biophysics and Medical Imaging, Universite Toulouse III Paul Sabatier, Toulouse (France); Department of Neuroradiology, Hopital Rangueil, CHU Toulouse, Toulouse (France); Cassol, Emmanuelle [Laboratory of Biophysics and Medical Imaging, Universite Toulouse III Paul Sabatier, Toulouse (France); McKnight, Tracy R. [Center for Molecular and Functional Imaging, University of California-San Francisco, San Francisco, CA (United States); Berchery, Delphine [Department of Medical Information, Institut Claudius Regaud, Toulouse (France); Marre, Delphine; Bachaud, Jean-Marc [Department of Radiation Oncology, Institut Claudius Regaud, Toulouse (France); Berry, Isabelle [Laboratory of Biophysics and Medical Imaging, Universite Toulouse III Paul Sabatier, Toulouse (France); Moyal, Elizabeth Cohen-Jonathan [Department of Radiation Oncology, Institut Claudius Regaud, Toulouse (France); Department of Therapeutic Innovation and Molecular Oncology, Institut Claudius Regaud, INSERM, U563, Toulouse (France)

2008-03-01

172

A Detector for Proton Computed Tomography  

SciTech Connect

Radiation therapy is a widely recognized treatment for cancer. Energetic protons have distinct features that set them apart from photons and make them desirable for cancer therapy as well as medical imaging. The clinical interest in heavy ion therapy is due to the fact that ions deposit almost all of their energy in a sharp peak – the Bragg peak- at the very end of their path. Proton beams can be used to precisely localize a tumor and deliver an exact dose to the tumor with small doses to the surrounding tissue. Proton computed tomography (pCT) provides direct information on the location on the target tumor, and avoids position uncertainty caused by treatment planning based on imaging with X-ray CT. The pCT project goal is to measure and reconstruct the proton relative stopping power distribution directly in situ. To ensure the full advantage of cancer treatment with 200 MeV proton beams, pCT must be realized.

Blazey, G.; et al.,

2013-12-06

173

Proton microscopy at GSI and 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 facilities have been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia for similar applications in dynamic material studies. Recently an international collaboration was formed to develop a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located at Gesellschaft fuer Schwerionenforschung (GSI) 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. These dynamic experiments will be driven with many energy sources including heavy ions, high explosives and lasers. The design of the proton microscope and expected radiographic performance is presented.

Merrill, Frank E [Los Alamos National Laboratory; Mariam, Fesseha G [Los Alamos National Laboratory; Golubev, A A [RUSSIA; Turtikov, V I [RUSSIA; Varentsov, D [GERMANY

2009-01-01

174

Electron - proton colliders  

Microsoft Academic Search

Electron-proton storage rings allow us to study the interaction between the two basic constituents of matter, electrons and quarks at very short distances. Such machines were first discussed in connection with the ISR but the idea was abandoned because of the anticipated low counting rate. The interest in electron-proton storage rings was rekindeled by the discovery of large pointlike cross

Wiik

1985-01-01

175

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

176

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

177

Comparison of Real-Time Water Proton Spectroscopy and Echo-Planar Imaging Sensitivity to the BOLD Effect at 3 T and at 7 T  

PubMed Central

Gradient-echo echo-planar imaging (GE EPI) is the most commonly used approach to assess localized blood oxygen level dependent (BOLD) signal changes in real-time. Alternatively, real-time spin-echo single-voxel spectroscopy (SE SVS) has recently been introduced for spatially specific BOLD neurofeedback at 3 T and at 7 T. However, currently it is not known how neurofeedback based on real-time SE SVS compares to real-time GE EPI-based. We therefore compared both methods at high (3 T) and at ultra-high (7 T) magnetic field strengths. We evaluated standard quality measures of both methods for signals originating from the motor cortex, the visual cortex, and for a neurofeedback condition. At 3 T, the data quality of the real-time SE SVS and GE EPI R2* estimates were comparable. At 7 T, the data quality of the real-time GE EPI acquisitions was superior compared to those of the real-time SE SVS. Despite the somehow lower data quality of real-time SE SVS compared to GE EPI at 7 T, SE SVS acquisitions might still be an interesting alternative. Real-time SE SVS allows for a direct and subject-specific T2* estimation and thus for a physiologically more plausible neurofeedback signal. PMID:24614912

Koush, Yury; Elliott, Mark A.; Scharnowski, Frank; Mathiak, Klaus

2014-01-01

178

Proton transport in proton exchange membranes.  

E-print Network

??This work investigated several proton exchange membranes (PEMs): perfluorosulfonic acid-based polymers (Nafion®), sulfonated poly(ether ether ketone) (S-PEEK), radiation-grafted ethylenetetrafluoroethylene-grafted-poly(styrene sulfonic) acid (ETFE-g-PSSA), sulfonated trifluorostyrene-co-substituted trifluorostyrene… (more)

Schmeisser, Jennifer Mary

2007-01-01

179

Proton radiography of electromagnetic fields generated by laser-driven plastic foils  

Microsoft Academic Search

We are conducting the first experiments using proton radiography to study electromagnetic fields generated by OMEGA laser-driven plastic foils. Transient E and B fields will be probed using proton deflectometry. Monoenergetic DD and D^3He protons are generated from direct-drive implosions of D^3He-filled glass micro-balloons. Using various mesh grids, both face-on and side-on proton images are recorded on CR-39 track detectors.

C. K. Li; T. C. Sangster; R. P. Town

2005-01-01

180

Electron - proton colliders  

SciTech Connect

Electron-proton storage rings allow us to study the interaction between the two basic constituents of matter, electrons and quarks at very short distances. Such machines were first discussed in connection with the ISR but the idea was abandoned because of the anticipated low counting rate. The interest in electron-proton storage rings was rekindeled by the discovery of large pointlike cross sections in lepton-hardon interactions and several/sup 2-15/ projects have been discussed during the past decade. However, despite a glorious past, which includes the discovery of quarks and neutral currents, and a multitude of proposals no electron-proton storage ring has ever been built. What we might learn by studying electron-proton collisions at high energies is discussed. After some brief comments on present proposals the proposed DESY ep project HERA is described as an example of how to realize such a machine.

Wiik, B.H.

1985-01-01

181

Proton aurora in the cusp H. U. Frey, S. B. Mende, and T. J. Immel  

E-print Network

Proton aurora in the cusp H. U. Frey, S. B. Mende, and T. J. Immel Space Sciences Laboratory) on the Imager for Magnetopause-to- Aurora Global Exploration (IMAGE) spacecraft observes intense ultraviolet; KEYWORDS: aurora, cusp, proton, precipitation, reconnection, interplanetary magnetic field (MLT) 1

California at Berkeley, University of

182

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

183

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

184

Evaluation of Magnetic Resonance Imaging-Compatible Needles and Interactive Sequences for Musculoskeletal Interventions Using an Open High-Field Magnetic Resonance Imaging Scanner  

SciTech Connect

In this article, we study in vitro evaluation of needle artefacts and image quality for musculoskeletal laser-interventions in an open high-field magnetic resonance imaging (MRI) scanner at 1.0T with vertical field orientation. Five commercially available MRI-compatible puncture needles were assessed based on artefact characteristics in a CuSO4 phantom (0.1%) and in human cadaveric lumbar spines. First, six different interventional sequences were evaluated with varying needle orientation to the main magnetic field B0 (0{sup o} to 90{sup o}) in a sequence test. Artefact width, needle-tip error, and contrast-to-noise ratio (CNR) were calculated. Second, a gradient-echo sequence used for thermometric monitoring was assessed and in varying echo times, artefact width, tip error, and signal-to-noise ratio (SNR) were measured. Artefact width and needle-tip error correlated with needle material, instrument orientation to B0, and sequence type. Fast spin-echo sequences produced the smallest needle artefacts for all needles, except for the carbon fibre needle (width <3.5 mm, tip error <2 mm) at 45{sup o} to B0. Overall, the proton density-weighted spin-echo sequences had the best CNR (CNR{sub Muscle/Needle} >16.8). Concerning the thermometric gradient echo sequence, artefacts remained <5 mm, and the SNR reached its maximum at an echo time of 15 ms. If needle materials and sequences are accordingly combined, guidance and monitoring of musculoskeletal laser interventions may be feasible in a vertical magnetic field at 1.0T.

Wonneberger, Uta, E-mail: uta.wonneberger@charite.d [University Medicine Berlin, Department of Radiology, Charite (Germany); Schnackenburg, Bernhard, E-mail: bernhard.schnackenburg@philips.co [Philips Medical Systems (Germany); Streitparth, Florian, E-mail: florian.streitparth@charite.de; Walter, Thula, E-mail: thula.walter@charite.de; Rump, Jens, E-mail: jens.rump@charite.de; Teichgraeber, Ulf K. M., E-mail: ulf.teichgraeber@charite.d [University Medicine Berlin, Department of Radiology, Charite (Germany)

2010-04-15

185

Proton therapy at Harvard.  

PubMed

Fractionated precision high-dose proton radiotherapy has been carried out at the Harvard Cyclotron Laboratory (HCL) since 1973, in a collaborative effort with the Radiation Medicine Department of Massachusetts General Hospital (MGH) and the Retina Service of the Massachusetts Eye and Ear Infirmary (MEEI). This paper will discuss proton treatment in general, treatment planning procedures, and results to date in major patient categories. 846 patients have been treated with fractionated proton therapy at the Harvard Cyclotron, with normal tissue and tumor responses consistent with an RBE of 1.1 for the proton beam. Proton beam therapy is the treatment of choice for patients with uveal melanomas, and chordomas and chondrosarcomas involving the skull base and cervical spine. Improved dose distribution possible with protons have allowed greater doses than are given conventionally to be delivered to patients with prostatic carcinoma, head and neck malignancies, ano-rectal cancers, and retroperitoneal tumors. Doses employed have been usually 10 to 20% greater than normally would be delivered in our department to such tumors. Generally, local control rates have been good. PMID:3001976

Munzenrider, J E; Austin-Seymour, M; Blitzer, P J; Gentry, R; Goitein, M; Gragoudas, E S; Johnson, K; Koehler, A M; McNulty, P; Moulton, G

1985-12-01

186

Laser-plasma interaction generated proton isochoric heating and focusing  

NASA Astrophysics Data System (ADS)

Fast ignition (FI) by laser-generated, ballistically focused protons is a new proposed alternative to the original concept of FI by laser-generated relativistic electrons. The key potential advantage in using proton FI lies in less-complex energy transport into dense plasma. Because of the high mass ratio of proton over electron, protons can maintain a stiff trace while traversing dense plasma. The requirement for proton FI is to heat D-T fuel with total 18 k3 proton energy at 3 MeV in 10 ps over 30 mum diameter. Due to the generation mechanism, a concave spherical target surface is used to focus protons. The focal plane position and focal size are currently under study. In this dissertation, for the first time, the blackbody radiation from the proton-heated target is used for the temperature measurement. Through the temperature measurement, focal plane position can be derived to be the location where the target's rear surface temperature peaks. In the experiments, the heated target's rear surface is reflected and imaged onto a detector using a spherically-bent multilayer mirror operating at near-normal incidence angle and a flat 45° turning mirror. Two sets of multilayer mirrors are precisely fabricated to reflect photons with energy of 68 eV and 256 eV. The XUV images of Al and polymer slabs at different separations from hemisphere are captured and analyzed to display the results of focal plane position for protons with different energy. Another novel technique for detecting both focal size and focal plane position of protons with different energy is proposed in this dissertation. In this technique, radiochromic films (RCF) are used to picture Cu mesh images projected by focused protons. The RCF consists of a series of films which stops different energy protons. By studying the magnifications and using the proportionalities of similar triangles, proton beam's focal plane position and focal size can be determined. The focal plane position calculated through this method is compared with the value derived from XUV images under the same condition in this dissertation.

Zhang, Bingbing

187

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

188

Dose-volume delivery guided proton therapy using beam on-line PET system  

SciTech Connect

Proton therapy is one form of radiotherapy in which the irradiation can be concentrated on a tumor using a scanned or modulated Bragg peak. Therefore, it is very important to evaluate the proton-irradiated volume accurately. The proton-irradiated volume can be confirmed by detection of pair annihilation gamma rays from positron emitter nuclei generated by the target nuclear fragment reaction of irradiated proton nuclei and nuclei in the irradiation target using a positron emission tomography (PET) apparatus, and dose-volume delivery guided proton therapy (DGPT) can thereby be achieved using PET images. In the proton treatment room, a beam ON-LINE PET system (BOLPs) was constructed so that a PET apparatus of the planar-type with a high spatial resolution of about 2 mm was mounted with the field of view covering the isocenter of the beam irradiation system. The position and intensity of activity were measured using the BOLPs immediately after the proton irradiation of a gelatinous water target containing {sup 16}O nuclei at different proton irradiation energy levels. The change of the activity-distribution range against the change of the physical range was observed within 2 mm. The experiments of proton irradiation to a rabbit and the imaging of the activity were performed. In addition, the proton beam energy used to irradiate the rabbit was changed. When the beam condition was changed, the difference between the two images acquired from the measurement of the BOLPs was confirmed to clearly identify the proton-irradiated volume.

Nishio, Teiji; Ogino, Takashi; Nomura, Kazuhiro; Uchida, Hiroshi [Particle Therapy Division, Research Center for Innovative Oncology, National Cancer Center, Kashiwa, 6-5-1 Kashiwano-ha, Kashiwa-shi, Chiba 277-8577 (Japan); Director, National Cancer Center Hospital, 5-5-1 Tsukiji, Chyuou-ku, Tokyo 104-0045 (Japan); The 5th Research Group, Hamamatsu Photonics K. K., 5000 Hirakuchi, Hamakita-shi, Shizuoka 434-8601 (Japan)

2006-11-15

189

Patient positioning for protontherapy using a proton range telescope  

NASA Astrophysics Data System (ADS)

A method is described for imaging integrated density along the beam path in phantoms that makes use of high energy proton beams. An application of the technique is in the positioning of patients in a proton therapy radiation facility. It makes use of a proton range telescope for density variation and X-Y detectors for planar positioning. The principle of the method was tested at a proton energy of 66 MeV. Good visual quality is seen in the tests. The measurements are compared with detailed Monte Carlo simulations, and good agreement is found. We apply the simulations to high energy proton beams (245 MeV) and show that the method should provide good visual quality and sensitivity for positioning at the higher energies necessary for whole body therapy.

Romero, J. L.; Osborne, J. H.; Brady, F. P.; Caskey, W.; Cebra, D. A.; Partlan, M. D.; Kusko, B. H.; King, R. S.; Mirshad, I.; Kubo, H.; Daftari, I.; W., Chu

1995-02-01

190

Initial studies on proton computed tomography using a silicon strip detector telescope  

NASA Astrophysics Data System (ADS)

We report initial results of a feasibility study of Proton Computed Tomography and Proton Transmission Radiography for applications in proton therapy treatment planning and patient positioning. The aim of the study is to explore experimentally if PCT, which is based on the measurement of the specific energy loss of protons traversing tissues of different density, may be preferred to X-ray Computed Tomography and X-ray radiography, which are presently used for radiation treatment planning and patient positioning in proton treatment centers. We present first data from proton transmission studies through a hollow aluminum cylinder taken with a telescope of silicon detectors with very high spatial and good energy resolution. In addition, we report the results of GEANT4 simulations of proton transport through the same object, which show good agreement with experimental results and explain the observed features of the proton transmission image.

Johnson, L.; Keeney, B.; Ross, G.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Zhang, L.; Bashkirov, V.; Schulte, R. W.; Shahnazi, K.

2003-11-01

191

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

192

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

193

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

194

Proton CT Setup at CV28 of IEN\\/CNEN  

Microsoft Academic Search

Although the idea of proton Computed Tomography (pCT) is not new, it is currently not available. It is still unknown if the image quality of pCT is sufficient for localizing tumors and if the accuracy of proton range calculations surpass that of X-ray CT based range calculations without significantly increasing the patient exposure. The spatial resolution of pCT is limited

I. Evseev; J. T. Assis; O. Yevseyeva; U. M. Vinagre Filho; J. A. P. Setti; H. R. Schelin; S. A. Paschuk; M. C. L. Klock; R. W. Schulte; R. T. Lopes

2005-01-01

195

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

196

Grazing Incidence Reflection and Scattering of MeV Protons  

E-print Network

Treating protons as de Broglie waves shows that up to a few MeV energies protons experience total external reflection using the index of refraction concept for the target earlier applied to electrons. Angular scattering distributions can be explained by random surface scattering as known for X-rays. Applied to the {\\it{Chandra}} and {\\it{XMM-Newton}} X-ray telescopes the calculated reflection efficiencies can explain the observed degradation of the X-ray CCDs for both missions. Some discussion about the possibility of realizing imaging sub-MeV and MeV proton optics is presented.

Bernd Aschenbach

2007-11-15

197

Proton affinity and proton transfer energy for selected organic molecules  

Microsoft Academic Search

The Hartree-Fock method in 6-311G** molecular orbitals basis set has been applied to calculations of proton affinities and proton transfer reaction energies for water methanol acetaldehyde ethanol acetone acetic acid methyl acetate and ethyl acetate.

T. Wroblewski; L. Ziemczonek; K. Szerement; G. P. Karwasz

2005-01-01

198

A Model of Proton  

E-print Network

I suggest to consider a proton as a body in a state of free precession. Such approach allows to define a proton as periodic system with two rotary degrees of freedom with corresponding frequency ratio and resonances. In result on a power scale the points corresponding to a birth of leptons are designated. The interrelation between masses of leptons is established through a fine structure constant. The given approach is distributed to a nucleus. Other representation is given on the nature of X-rays which connect with a charge of a nucleus and its mass.

Vladislav Shchegolev

2005-06-14

199

Proton-transfer laser  

SciTech Connect

Stimulated radiation was generated by an active medium where the population inversion results from excited-state intramolecular proton-transfer reaction. The operation of a salicylamide pulsed laser, built on this principle, is described. The laser shows a 5% energy conversion efficiency when pumped with 5-20 mJ of 308-nm radiation.

Acuna, A.U.; Costela, A.; Munoz, J.M.

1986-06-19

200

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

201

Pionic effect on proton spin  

SciTech Connect

Assuming the physical proton as a quark core dressed by a virtual pion cloud, we have calculated the proton spin due to orbital angular momentum of the pion cloud as well as the effect of the pion cloud on the dilution of the proton spin.

Sahu, Sarira [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, C.U., A. Postal 70-543, 04510 Mexico DF (Mexico)

2005-04-01

202

Folding model analysis of proton radioactivity of spherical proton emitters  

E-print Network

Half lives of the decays of spherical nuclei away from proton drip line by proton emissions are estimated theoretically. The quantum mechanical tunneling probability is calculated within the WKB approximation. Microscopic proton-nucleus interaction potentials are obtained by single folding the densities of the daughter nuclei with M3Y effective interaction supplemented by a zero-range pseudo-potential for exchange along with the density dependence. Strengths of the M3Y interaction are extracted by fitting its matrix elements in an oscillator basis to those elements of the G-matrix obtained with the Reid-Elliott soft-core nucleon-nucleon interaction. Parameters of the density dependence are obtained from the nuclear matter calculations. Spherical charge distributions are used for calculating the Coulomb interaction potentials. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes of proton rich nuclei for proton emissions from 26 ground and isomeric states of spherical proton emitters.

D. N. Basu; P. Roy Chowdhury; C. Samanta

2005-03-03

203

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

204

Study of spatial resolution of proton computed tomography using a silicon strip detector  

NASA Astrophysics Data System (ADS)

Proton computed tomography (CT) is an imaging technique using a high-energy proton beam penetrating the human body and shows promise for improving the quality of cancer therapy with high-energy particle beams because more accurate electron density distribution measurements can be achieved with proton CT. The deterioration of the spatial resolution owing to multiple Coulomb scattering is, however, a crucial issue. The control of the radiation dose and the long exposure time are also problems to be solved. We have developed a prototype system for proton CT with a silicon strip detector and performed a beam test for imaging. The distribution of the electron density has been measured precisely. We also demonstrated an improvement in spatial resolution by reconstructing the proton trajectory. A spatial resolution of 0.45 mm is achieved for a 25-mm-thick polyethylene object. This will be a useful result for upgrading proton CT application for practical use.

Saraya, Y.; Izumikawa, T.; Goto, J.; Kawasaki, T.; Kimura, T.

2014-01-01

205

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. PMID:20735815

2010-01-01

206

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

207

Polarized protons at RHIC  

SciTech Connect

The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 {times} 10{sup 32}/cm{sup 2}/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined.

Makdisi, Y.

1992-10-01

208

Polarized protons at RHIC  

SciTech Connect

The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 {times} 10{sup 32}/cm{sup 2}/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined.

Makdisi, Y.

1992-01-01

209

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

210

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

211

Design and simulation of magnetic coil for steering of cyclotron proton beam  

Microsoft Academic Search

The PETtrace cyclotron is used for the production of pharmaceutical radioisotopes delivered to local hospitals for cancer diagnosis and nuclear imaging. The fine adjustment of where the proton beam hits the target can improve the production of radioisotopes. The design and simulation of a magnetic coil to steer the proton beam by deflecting it using magnetic force was conducted for

Maslina Mohd Ibrahim

2011-01-01

212

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

213

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

PubMed Central

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 4 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 4 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

2014-01-01

214

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

215

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. PMID:16189526

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

2005-01-01

216

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

217

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

218

Measurement of asymmetric component in proton-proton collisions  

E-print Network

It is argued that a standard measurement of multiplicities in proton-proton collisions is sufficient to construct a single nucleon fragmentation function. A proposed method is based on measurement of mean values of produced particles and pairs of particles in symmetric and asymmetric bins

Adam Bzdak

2009-04-06

219

Proton in SRF Niobium  

SciTech Connect

Hydrogen is a difficult impurity to physically deal with in superconducting radio frequency (SRF) niobium, therefore, its properties in the metals should be well understood to allow the metal's superconducting properties to be optimized for minimum loss in the construction of resonant accelerator cavities. It is known that hydrogen is a paramagnetic impurity in niobium from NMR studies. This paramagnetism and its effect on superconducting properties are important to understand. To that end analytical induction measurements aimed at isolating the magnetic properties of hydrogen in SRF niobium are introduced along with optical reflection spectroscopy which is also sensitive to the presence of hydrogen. From the variety, magnitude and rapid kinetics found in the optical and magnetic properties of niobium contaminated with hydrogen forced a search for an atomic model. This yielded quantum mechanical description that correctly generates the activation energy for diffusion of the proton and its isotopes not only in niobium but the remaining metals for which data is available. This interpretation provides a frame work for understanding the individual and collective behavior of protons in metals.

Wallace, John Paul [Casting Analysis Corp, Weyers Cave, VA. 24486 (United States)

2011-03-31

220

Proton radiobiology, radiosurgery and radiotherapy.  

PubMed

This review briefly traces the historical developments of proton radiobiology, radiosurgery and radiotherapy for the benefit of young researchers and clinicians entering into this field. In preparing to use protons in radiosurgery and radiotherapy, radiobiological effects of protons were studied extensively by various groups, including the University of California at Berkeley, the University of Uppsala, Massachusetts General Hospital, and the Harvard Cyclotron Laboratory. Considerable work on proton radiobiology was also done because protons are a major component of the radiation environment in space. The biological effects of proton beams were found to be quantitatively and qualitatively similar to conventional radiations used in radiotherapy. The relative biological effectiveness (RBE) of protons suitable for large-field radiotherapy, compared with 60Co gamma-rays, is generally in the range 1.0-1.25, and remains the same with depth of penetration, except for the descending portion of the depth-dose curve. Also, unlike other heavier charged particles and neutrons, the RBE of high-energy protons, which are suitable for large-field radiotherapy, compared with 60Co gamma-rays, is generally found to be independent of the fraction size in in vivo experiments. The oxygen enhancement ratio for high-energy protons is not significantly different from that of X-rays. An RBE = 1.1, compared with 60Co gamma-rays, is generally used in the clinical application of protons; however, the radiobiological data on mouse, rat, rabbit and primate suggest that the gastrointestinal tissues may be relatively more sensitive to protons. About 13,000 patients have been treated with protons at about 15 facilities around the world. Nearly half of these patients were neurosurgical patients treated with stereotactic radiosurgery. The pioneering efforts at the Harvard Cyclotron in collaboration with the Massachusetts General Hospital and the Massachusetts Eye and Ear Infirmary were responsible for the development of proton treatment for choroidal melanoma and for the tumours of the skull base and spine. There has been extensive confirmation of these results by other groups, especially the groups at Lawrence Berkeley Laboratory and Paul Scherrer Institute. The first medically dedicated proton facility is in operation at Loma Linda University in California. The construction in the USA of another proton treatment facility at Massachusetts General Hospital has been decided upon, and there are plans for many more worldwide. PMID:7897273

Raju, M R

1995-03-01

221

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

222

The decay of the proton  

Microsoft Academic Search

The principal decay modes of subatomic particles are governed by fundamental conservation laws, and it is recounted how traditional views of conservation laws have been altered by the development of modern theories of elementary particle interactions. Proton decay experiments have gradually increased the empirical lower boundary on the lifetime of the proton. It is now known to have a lifetime

Steven Weinberg

1981-01-01

223

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

224

Evaluation And Comparison Of Image Reconstruction Algorithms For Positron Emission Tomography With Time-Of-Flight Information (Tofpet)  

NASA Astrophysics Data System (ADS)

Two new image reconstruction algorithms, the "Metz filter method" (MF) and the "simple EM method" (SEM), have been developed for TOFPET. The results of these new methods were evaluated systematically in computer simulation studies and compared to those produced by three established algorithms: the most-likely position method (MLP), the confidence weighting method (CW), and the estimated posterior-density weighting method (EPDW). Relative computational efficiencies and image quality descriptors such as reconstructed image resolution, noise magnitude, and quantitative accuracy have been investigated. In most cases, the MF method appears to provide a superior compromise between acceptable image quality and reasonable computation efficiency.

Chen, Chin-Tu; Metz, Charles E.

1984-08-01

225

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

226

An 800-MeV proton radiography facility for dynamic experiments  

NASA Astrophysics Data System (ADS)

The capability has successfully been 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 dynamic 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 either on 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 a high explosive sample 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.; Ables, E.; Adams, Ken; Alrick, K. R.; Amann, J. F.; Balzar, Stephen; Barnes, P. D., Jr.; Crow, M. L.; Cushing, S. B.; Eddleman, J. C.; Fife, T. T.; Flores, Paul; Fujino, D.; Gallegos, R. A.; Gray, N. T.; Hartouni, E. P.; Hogan, G. E.; Holmes, V. H.; Jaramillo, S. A.; Knudsson, J. N.; London, R. K.; Lopez, R. R.; McDonald, T. E.; McClelland, J. B.; Merrill, F. E.; Morley, K. B.; Morris, C. L.; Naivar, F. J.; Parker, E. L.; Park, H. S.; Pazuchanics, P. D.; Pillai, C.; Riedel, C. M.; Sarracino, J. S.; Shelley, F. E., Jr.; Stacy, H. L.; Takala, B. E.; Thompson, Richard; Tucker, H. E.; Yates, G. J.; Ziock, H.-J.; Zumbro, J. D.

1999-11-01

227

Proton-Antiproton Colliders  

NASA Astrophysics Data System (ADS)

The two proton-antiproton colliders, the SppbarS at CERN and the Tevatron at Fermilab, have dominated the high energy frontier for the past 30 years and have made some of the most significant contributions to the understanding of the fundamental nature of matter, including the discovery of the W and Z bosons and the Top quark. They have both pushed technology to the limit. The Tevatron was the first large superconducting storage ring from which followed HERA at DESY, RHIC at BNL and finally the Large Hadron Collider at CERN. In this talk, a personal account of the trials and tribulations of running these very difficult machines will be given and their relevance to the design of the LHC discussed.

Evans, Lyndon

2011-04-01

228

The proton (nuclear) microprobe  

NASA Astrophysics Data System (ADS)

The scanning proton microprobe (SPMP) is closely related to the scanning electron microprobe (SEMP) or scanning electron microscope (SEM) with X-ray detector. Though the much greater elemental sensitivity of the SPMP is inherent in the physics, the generally inferior spatial resolution of the SPMP is not inherent and big improvements are possible, As its alternative name would imply, the SPMP is often used with heavier particle beams and with nuclear rather than atomic reactions. Its versatility and quantitative accuracy have justified greater instrumentation and computer power than that associated with other microprobes. It is fast becoming an industrially and commercially important instrument and there are few fields of scientific research in which it has not played a part. Notable contributions have been made in biology, medicine, agriculture, semiconductors, geology, mineralogy, extractive metallurgy, new materials, archaeology, forensic science, catalysis, industrial problems and reactor technology.

Legge, G. J. F.

1989-04-01

229

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

230

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

231

Afternoon Subauroral Proton Precipitation Resulting from Ring Current - Plasmasphere Interaction  

NASA Astrophysics Data System (ADS)

Although the dominant loss processes for ring current ions are collisional, wave-particle interactions are also believed to play an important role as they provide a mechanism for the rapid decay of the ring current during the early recovery phase of geomagnetic storms. Considerable attention has been given to regions of spatial overlap between energetic, anisotropic ring current ions and cold, dense plasmaspheric material that should be particularly conducive to the growth of electromagnetic ion cyclotron (EMIC) waves. Resonant interaction between ring current ions and EMIC waves results in pitch angle scattering and subsequent precipitation of the energetic ions into the upper atmosphere. Global imaging of the proton aurora by the Far Ultraviolet (FUV) Spectrographic Imager (SI) on-board the IMAGE satellite has led to the identification of arcs of precipitating protons at latitudes equatorward of and separated from the main proton auroral oval in the afternoon local time sector. We investigate the occurrence of these arcs and their relationship with the plasmasphere and electromagnetic ion cyclotron waves. In a four month study interval including sixteen events, we find that the detached proton arcs are more likely to occur during geomagnetically disturbed periods and specifically at times when enhanced energetic ion densities and temperature anisotropies are observed in the equatorial magnetosphere. The disturbance-time arcs tend to be located at lower magnetic latitudes and are consistently associated with plasmaspheric plumes as observed by the IMAGE Extreme Ultraviolet (EUV) instrument. Wave data from the POLAR Magnetic Field Experiment (MFE) available for two of the detached arc events indicate the presence of strong EMIC waves near the equator in the vicinity of the proton precipitation region.

Spasojevic, M.; Thomsen, M. F.; Chi, P. J.; Sandel, B. R.

2004-12-01

232

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)], 10.1016/S0030-4018(96)00325-2 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)], 10.1016/S0168-9002(03)01368-8 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

233

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

234

Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites  

E-print Network

While magnetic resonance imaging (MRI) derives its signal from protons in water, additional biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of these much weaker signals ...

Kok, Trina

2012-01-01

235

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

236

Proton conduction in discotic mesogens.  

PubMed

In this communication, we show that liquid crystalline phases lower the activation energy barrier for proton transport. The liquid crystalline phases were obtained using a triphenylene core with alkyl chains bearing a triazole moiety at their termini. PMID:21483908

Basak, Dipankar; Christensen, Scott; Surampudi, Sravan K; Versek, Craig; Toscano, Daniel T; Tuominen, Mark T; Hayward, Ryan C; Venkataraman, D

2011-05-21

237

Statistical behavior of proton and electron auroras during substorms S. B. Mende, H. U. Frey, B. J. Morsony, and T. J. Immel  

E-print Network

Statistical behavior of proton and electron auroras during substorms S. B. Mende, H. U. Frey, B. J (WIC) usually dominated by electron aurora. Images taken by WIC and by the Spectrographic Imager SI12 channel, responsive to proton aurora, were transformed into rectangular magnetic latitude (ML

California at Berkeley, University of

238

Proton acceleration experiments with Z-Petawatt.  

SciTech Connect

The outline of this presentation: (1) Proton acceleration with high-power lasers - Target Normal Sheath Acceleration concept; (2) Proton acceleration with mass-reduced targets - Breaking the 60 MeV threshold; (3) Proton beam divergence control - Novel focusing target geometry; and (4) New experimental capability development - Proton radiography on Z.

Arefiev, A. (University of Texas at Austin); Schaumann, G. (Technische Universitat Darmstadt, Germany); Deppert, O. (Technische Universitat Darmstadt, Germany); Rambo, Patrick K.; Roth, M. (Technische Universitat Darmstadt, Germany); Geissel, Matthias; Schwarz, Jens; Sefkow, Adam B.; Atherton, Briggs W.; Kimmel, Mark W.; Schollmeier, Marius; Breizman, B. (University of Texas at Austin)

2010-08-01

239

Proton Magnetic Resonance Spectrum of Propane  

Microsoft Academic Search

Exact proton magnetic resonance eigenspectra of the spin Hamiltonian are calculated for a system containing one group of six identical protons and one group of two identical protons. The method of calculation considers each group of identical protons as a composite ``particle'' with fixed total spin, and does not require determination of the explicit form of the zero-order eigenfunctions. The

Donald R. Whitman; Lars Onsager; Martin Saunders; Hubert E. Dubb

1960-01-01

240

Proton beam monitor chamber calibration  

NASA Astrophysics Data System (ADS)

The first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic proton beam. For the latter, this paper also compares two independent dosimetry techniques to calibrate the beam monitor chambers: absolute dosimetry (of the number of protons exiting the nozzle) with a Faraday cup and reference dosimetry (i.e. determination of the absorbed dose to water under IAEA TRS-398 reference conditions) with an ionization chamber. To compare the two techniques, Monte Carlo simulations were performed to convert dose-to-water to proton fluence. A good agreement was found between the Faraday cup technique and the reference dosimetry with a plane-parallel ionization chamber. The differences—of the order of 3%—were found to be within the uncertainty of the comparison. For cylindrical ionization chambers, however, the agreement was only possible when positioning the effective point of measurement of the chamber at the reference measurement depth—i.e. not complying with IAEA TRS-398 recommendations. In conclusion, for cylindrical ionization chambers, IAEA TRS-398 reference conditions for monoenergetic proton beams led to a systematic error in the determination of the absorbed dose to water, especially relevant for low-energy proton beams. To overcome this problem, the effective point of measurement of cylindrical ionization chambers should be taken into account when positioning the reference point of the chamber. Within the current IAEA TRS-398 recommendations, it seems advisable to use plane-parallel ionization chambers—rather than cylindrical chambers—for the reference dosimetry of pseudo-monoenergetic proton beams.

Gomà, C.; Lorentini, S.; Meer, D.; Safai, S.

2014-09-01

241

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

242

Cataractogenic effects of proton radiation  

E-print Network

CATARACTOGENIC EFFECTS OF PROTON RADIATION A Thesis by James Ronald Kyzar Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1972 Major Subject...: Veterinary Physiology CATARACTOGENIC EFFECTS OF PROTON RADIATION A Thesis by James Ronald Kyzar Approved as to style and content by: (Char of Committee) (Head of Depar ent) (Membei / (Member (Member ) May 1972 ABSTRACT Cataractogenic Effects...

Kyzar, James Ronald

2012-06-07

243

Voltage-gated Proton Channels  

PubMed Central

Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ?pH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

DeCoursey, Thomas E.

2014-01-01

244

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

245

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

SciTech Connect

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 {approx}4%, and a divergency angle of 2 Degree-Sign can be obtained, which might have diverse applications in medical therepy and proton imaging in future.

Liu Qingcao; Liu Meng; Ding Pengji; Liu Zuoye; Sun Shaohua; Liu Xiaoliang; Lu Xing; Guo Zeqin; Hu Bitao [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Yu Tongpu [Department of Physics, National University of Defense Technology, Changsha 410073 (China); Institut fuer Theoretische Physik I, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf (Germany)

2012-09-15

246

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

247

The physics of Cerenkov light production during proton therapy.  

PubMed

There is increasing interest in using Cerenkov emissions for quality assurance and in vivo dosimetry in photon and electron therapy. Here, we investigate the production of Cerenkov light during proton therapy and its potential applications in proton therapy. A primary proton beam does not have sufficient energy to generate Cerenkov emissions directly, but we have demonstrated two mechanisms by which such emissions may occur indirectly: (1) a fast component from fast electrons liberated by prompt gamma (99.13%) and neutron (0.87%) emission; and (2) a slow component from the decay of radioactive positron emitters. The fast component is linear with dose and doserate but carries little spatial information; the slow component is non-linear but may be localised.The properties of the two types of emission are explored using Monte Carlo modelling in GEANT4 with some experimental verification. We propose that Cerenkov emissions could contribute to the visual sensation reported by some patients undergoing proton therapy of the eye and we discuss the feasibility of some potential applications of Cerenkov imaging in proton therapy. PMID:25365447

Helo, Y; Kacperek, A; Rosenberg, I; Royle, G; Gibson, A P

2014-12-01

248

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

249

Generation of proton aurora by magnetosonic waves  

NASA Astrophysics Data System (ADS)

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

2014-06-01

250

Computing proton dose to irregularly moving targets  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

251

2002 IEEE NSS/MIC pCT: Hartmut F.-W. Sadrozinski , SCIPP Towards Proton Computed Tomography  

E-print Network

Deposit in 1mm [MeV/mm] Water Depth [cm] E = 130 MeV E = 250 MeV Imaging Treatment ·Relatively low Ph.D. Theses at PSI and Harvard Cyclotron (U. Schneider & P. Zygmanski) · Existence of high bandwidth. & Pedroni E. (1995), "Proton radiography as a tool for quality control in proton therapy," Med Phys. 22, 353

California at Santa Cruz, University of

252

MR and Proton MR Spectroscopy of the Brain in Hyperhomocysteinemia Caused by Methylenetetrahydrofolate Reductase Deficiency  

Microsoft Academic Search

Summary: MR imaging showed severe atrophy and large areas without myelination in the brain of a girl with methylenetetrahy- drofolate reductase deficiency. Proton MR spectroscopy re- vealed mild signal reduction of N-acetylaspartate. After treat- ment with betaine, a second MR imaging study revealed a decrease in the size of the hypomyelinated zones that was par- alleled by improved clinical status

V. Engelbrecht; M. Rassek; J. Huismann; U. Wendel

1997-01-01

253

Low Proton Conductance of Plant Cuticles and Its Relevance to the Acid-Growth Theory 1  

PubMed Central

Evidence obtained on the relation between the pH of the medium and the growth of intact stem sections is compatible with the acid-growth theory only if the proton conductance of the cuticle is so low that the cuticle is an effective barrier to the entry or exit of protons from the tissue. By measuring the rate at which protons cross frozen-thawed epidermal strips of sunflower (Helianthus annuus L.) and soybean hypocotyls (Glycine max Morr.) and enzymically isolated cuticles of Berberis aquifolium Persh. and tomato (Lycopersicum esculentum Mill.) fruit, we have now demonstrated the low proton conductance of the cuticular layer. Unless the conductance is enhanced by abrasion of the cuticle or by removal of the cuticular waxes, proton movement into and out of a tissue across the cuticle will be significant only over long time periods. Images PMID:16661976

Dreyer, S. Ann; Seymour, Virginia; Cleland, Robert E.

1981-01-01

254

Locating protonated amines in clathrates.  

PubMed

The structures and inherent stabilities of hydrated, protonated ammonia, select protonated primary, secondary, and tertiary amines as well as tetramethylammonium with 19-21 water molecules were investigated using infrared photodissociation (IRPD) spectroscopy and blackbody infrared radiative dissociation (BIRD) at 133 K. Magic number clusters (MNCs) with 20 water molecules were observed for all ions except tetramethylammonium, and the BIRD results indicate that these clusters have stable structures, which are relatively unaffected by addition of one water molecule but are disrupted in clusters with one less water molecule. IRPD spectra in the water free O-H stretch region are consistent with clathrate structures for the MNCs with 20 water molecules, whereas nonclathrate structures are indicated for tetramethylammonium as well as ions at the other cluster sizes. The locations of protonated ammonia and the protonated primary amines either in the interior or at the surface of a clathrate were determined by comparing IRPD spectra of these ions to those of reference ions; Rb(+) and protonated tert-butylammonia with 20 water molecules were used as references for an ion in the interior and at the surface of a clathrate, respectively. These results indicate that protonated ammonia is in the interior of the clathrate, whereas protonated methyl- and n-heptylamine are at the surface. Calculations suggest that the number of hydrogen bonds in these clusters does not directly correlate with structural stability, indicating that both the number and orientation of the hydrogen bonds are important. These experimental results should serve as benchmarks for computational studies aimed at elucidating ion effects on the hydrogen-bonding network of water molecules and the surface activity of ions. PMID:24007314

Chang, Terrence M; Cooper, Richard J; Williams, Evan R

2013-10-01

255

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

256

A simple solution of the proton crisis  

E-print Network

In this work we suggest a simple theoretical model of the proton able to effectively solve proton spin crisis. Within domain of applicability of this simple model proton consists only of two u quarks and one d quarks (two of which have spin opposite to proton and one identical to proton) and one neutral vector phi meson (with spin two times larger than proton spin and directed identically to proton spin). This model is in full agreement not only with existing DIS experiments, but also with spin and electric charge conservation as well as in a satisfactory agreement with rest mass-energy conservation (since phi meson mass is close to proton rest mass). Our model opens an interesting possibility of the solution of the quarks and leptons families problem (proton is not an absolutely non-strange particle, but only a particle with almost totally effectively hidden strange).

Pankovic, Vladan

2014-01-01

257

A simple solution of the proton crisis  

E-print Network

In this work we suggest a simple theoretical model of the proton able to effectively solve proton spin crisis. Within domain of applicability of this simple model proton consists only of two u quarks and one d quarks (two of which have spin opposite to proton and one identical to proton) and one neutral vector phi meson (with spin two times larger than proton spin and directed identically to proton spin). This model is in full agreement not only with existing DIS experiments, but also with spin and electric charge conservation as well as in a satisfactory agreement with rest mass-energy conservation (since phi meson mass is close to proton rest mass). Our model opens an interesting possibility of the solution of the quarks and leptons families problem (proton is not an absolutely non-strange particle, but only a particle with almost totally effectively hidden strange).

Vladan Pankovic

2013-12-24

258

Measuring the strong electrostatic and magnetic fields with proton radiography for ultra-high intensity laser channeling on fast ignitiona)  

NASA Astrophysics Data System (ADS)

In order to investigate the intense laser propagation and channel formation in dense plasma, we conducted an experiment with proton deflectometry on the OMEGA EP Laser facility. The proton image was analyzed by tracing the trajectory of mono-energetic protons, which provides understanding the electric and magnetic fields that were generated around the channel. The estimated field strengths (E ˜ 1011 V/m and B ˜ 108 G) agree with the predictions from 2D-Particle-in-cell (PIC) simulations, indicating the feasibility of the proton deflectometry technique for over-critical density plasma.

Uematsu, Y.; Ivancic, S.; Iwawaki, T.; Habara, H.; Lei, A. L.; Theobald, W.; Tanaka, K. A.

2014-11-01

259

Proton-proton fusion in lattice effective field theory  

E-print Network

The proton-proton fusion rate is calculated at low energy in a lattice effective field theory (EFT) formulation. The strong and the Coulomb interactions are treated non-perturbatively at leading order in the EFT. The lattice results are shown to accurately describe the low energy cross section within the validity of the theory at energies relevant to solar physics. In prior work in the literature, Coulomb effects were generally not included in non-perturbative lattice calculations. Work presented here is of general interest in nuclear lattice EFT calculations that involve Coulomb effects at low energy. It complements recent developments of the adiabatic projection method for lattice calculations of nuclear reactions.

Rupak, Gautam

2014-01-01

260

Hot-cold plasma interactions and the generation of transient dayside sub-auroral proton precipitation  

NASA Astrophysics Data System (ADS)

The IMAGE spacecraft obtained the first global images of the proton aurora. One of the discoveries from these images was proton precipitation equatorward of the nominal auroral oval. This precipitation can be observed for approximately 10 minutes immediately following a large solar wind pressure pulse. Various mechanisms have been proposed for producing this precipitation. Here, precipitation due to scattering from electromagnetic ion cyclotron (EMIC) waves is investigated using data from the IMAGE FUV and EUV imagers and in situ data from the Los Alamos geosynchronous spacecraft. In the proposed EMIC wave mechanism, the compression of the dayside magnetosphere enhances the growth rate of the wave instability. These waves scatter hot, ring current protons into the atmospheric loss cone, reducing the proton temperature anisotropy (the free energy source of the waves). Two features of the proton precipitation from these waves require explanation. First, the precipitation pattern may peak at any local time on the dayside between about 09 and 15. Second, the precipitation pattern has limited latitudinal extent (typically less than about 10 degrees) and is often separated from the main auroral oval. The local time peak in the precipitation pattern is related to the characteristics of the solar wind pressure pulse that causes EMIC wave growth. The separation of the precipitation pattern from the main auroral oval is related to properties of the hot and cold plasma within the magnetosphere that enhance EMIC wave growth.

Fuselier, S. A.; Gary, S. P.; Thomsen, M. F.; Claflin, E. S.; Hubert, B.; Immel, T. J.; Sandel, B. R.

2003-12-01

261

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

PubMed Central

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 The study cohort consists of 13 adolescents between the ages of 12–18 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 ten patients was delivered to the thecal sac and exiting nerve roots only, whereas the remaining three 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 Equivalents (CGE) given in 1.8 CGE fractions. MR images of the spine were obtained after completion of radiotherapy. Results MR 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. MR 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. PMID:17449195

Krejcarek, Stephanie C.; Grant, P. Ellen; Henson, John. W.; Tarbell, Nancy J.; Yock, Torunn I.

2007-01-01

262

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

263

Observations of the H? hydrogen emission on Spitsbergen during the proton event of January 22, 2012  

NASA Astrophysics Data System (ADS)

The behavior of the H? hydrogen emission at Barentsburg observatory during precipitation of high-energy solar protons and sudden impulse (SI) on January 22, 2012, was studied. The emission intensity was determined with a spectrometer, which gives the meridian arc spectrum image. It has been shown that the H? emission luminosity onset coincides with SI and is caused by precipitation of solar wind protons through the cusp.

Roldugin, A. V.; Pilgaev, S. V.; Roldugin, V. C.

2014-11-01

264

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

265

Optical Emissions from Proton Aurora  

NASA Technical Reports Server (NTRS)

Hydrogen emissions are the signature of proton aurora. The Doppler-shifted hydrogen emission lines can be interpreted in terms of the mean energy of the precipitating protons. A red shifted component of the line profiles observed from the ground indicates upward going hydrogen atoms due to angular redistribution of the precipitation. Secondary electrons from ionization and stripping collisions also contribute to the auroral emissions. Since the energy distribution of these secondaries has a lower mean energy than secondary electrons in electron aurora, the relative brightness of eniission features differs from that in electron aurora. The secondaries contribute little to additional ionization. These differences between proton and electron aurora can lead to misinterpretation when brightness ratios are used to derive ionospheric conductances with parameterizations that are based on electron aurora.

Lummerzheim, D.; Galand, M.; Kubota, M.

2003-01-01

266

Spin models of the proton  

SciTech Connect

We have constructed a model of the proton spin based on a broken SU(6) parameterization for the spin-weighted valence quark distributions in a longitudinally polarized proton. The polarized sea and gluon distributions are assumed to have simple relations to the corresponding unpolarized structure functions. The sum rules, which involve the non-singlet components of the structure function xg/sub 1/, imply that the valence quarks carry about 78% of the proton spin, while the spin carried by sea quarks is negative. Recent EMC data suggest a model in which the sea quarks carry a large negative polarization, whereas certain theoretical arguments favor a model with a smaller negatively polarized sea. These models are discussed with reference to the sum rules. Experiments are suggested which will discriminate between these models. 24 refs., 4 figs.

Ramsey, G.P.

1988-10-20

267

Proton Mass Shift in Muonic Hydrogen Atom  

E-print Network

We show that the value of the proton mass depends on each bound state of muonic or electronic hydrogen atom. The charged particle bound to the proton produces magnetic field inside the proton. This makes a change to the amount of chiral condensate inside the proton. The change gives rise to the shift in the value of the proton mass. Numerically, the shift in the $2S$ state of the muonic hydrogen atom can be of the order of $0.1$ meV. The effect may solve the puzzle of the proton radius.

Aiichi Iwazaki

2014-08-11

268

Nuclear magnetic resonance imaging.  

PubMed

NMR imaging is based on the ability to induce and monitor resonance of the magnetic moment of nuclei with an odd number of protons and/or neutrons in the presence of magnetic fields. By the use of magnetic fields whose strength varies with position, it is possible to define both the location and concentration of resonant nuclei, and, thereby, to create images that reflect their distribution in tissue. Hydrogen because it is the most sensitive of the stable nuclei to NMR and because it is also the most abundant nucleus in the body, is ideally suited for NMR imaging. PMID:7323305

Crooks, L; Herfkens, R; Kaufman, L; Hoenninger, J; Arakawa, M; McRee, R; Watts, J

1981-01-01

269

Proton beams in radiation therapy.  

PubMed

The rationale for study of proton radiation therapy is that, for some anatomic sites and tumors, the treatment volume is smaller; i.e., there is less irradiation of nontarget tissue while the target is included in three dimensions at each treatment session. As a result, the dose to the target can be raised. The consequence is that the tumor control probability improves and the frequency and severity of treatment-related morbidity decrease. These results come about from the physical fact that the proton range in tissue is finite; in comparison, absorption of photons is an exponential function and, hence, some dose is received for the full-beam path through the body. Accordingly, the dose deep to the target for proton treatments can be zero for each beam path. This situation provides a virtually certain means of improving the treatment outcome for selected categories of patients. Experience to date with proton radiation therapy has been quite limited. As of June 1991, the total number of proton radiation-treated patients was 11,763 from the various centers. Of that number, approximately 46% and 32% have been treated for small benign intracranial lesions (principally pituitary adenomas and arteriovenous malformations) and for tumors of the eye, respectively. Thus, only some 2500 patients have been treated for all other tumor types. The results from three centers and approximately 2800 patients with uveal melanoma are that the local control rate was 96% (for failures in-field, marginal, and in other parts of the eye). The local control results for chondrosarcomas and chordomas of the skull base are 91% and 65%, respectively. These percentages compare with some 35% achieved with conventional treatment. Experience with arteriovenous malformations indicates that control of bleeding and disappearance of the lesion are comparable to those achieved by other procedures. The developments from the proton therapy programs have contributed greatly to radiation treatment planning, e.g., the first three-dimensional treatment planning system put into regular clinical use (uveal melanoma), beam's eye view, digital-reconstructed radiograph, dose-volume histograms, and definitions of the uncertainty in dose around any defined point. The potential for clinical gains is high. In May 1991, the Proton Radiation Oncology Group was formed to design, supervise, and coordinate clinical trials and to assist in data analysis. The efficacy of proton radiation therapy will be compared with that of photon therapy of the very highest technology. PMID:1311773

Suit, H; Urie, M

1992-02-01

270

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

271

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. PMID:21626923

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

2011-01-01

272

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. PMID:23575366

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

2013-01-01

273

Determining the mechanism of cusp proton aurora  

NASA Astrophysics Data System (ADS)

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

2013-04-01

274

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

275

Determining the mechanism of cusp proton aurora.  

PubMed

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. PMID:23575366

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

2013-01-01

276

Resist materials for proton micromachining  

NASA Astrophysics Data System (ADS)

The production of high aspect ratio microstructures is a potential growth area. The combination of deep X-ray lithography with electroforming and micromolding (i.e. LIGA) is one of the main techniques used to produce 3D microstructures. The new technique of proton micromachining employs focused MeV protons in a direct write process which is complementary to LIGA, e.g. micromachining with 2 MeV protons results in microstructures with a height of 63 ?m and lateral sub-micrometer resolution in PMMA resist. The aim of this paper is to investigate the capabilities of proton micromachining as a lithographic technique. This involves the study of different types of resists. The dose distribution of high molecular weight PMMA is compared with three other types of resist: First the positive photo resist AZ P4620 will be discussed and then PMGI SF 23, which can be used as a deep UV, e-beam or X-ray resist. Finally SU-8, a new deep UV negative type of chemically amplified resist will be discussed. All these polymers are applied using the spin coating technique at thicknesses of between 1 and 36 ?m

van Kan, J. A.; Sanchez, J. L.; Xu, B.; Osipowicz, T.; Watt, F.

1999-10-01

277

Regulation of immune responses by proton channels.  

PubMed

The identification of the HVCN1 gene, encoding the only mammalian voltage-gated proton channel, prompted a number of studies on how proton channels affect cellular functions. As their expression is mainly restricted to immune cells, it is not surprising that proton channels regulate different aspects of immune responses. In this review, I will examine the current knowledge of voltage-gated proton channels in both innate and adaptive responses and assess the remaining outstanding questions. PMID:24890927

Capasso, Melania

2014-10-01

278

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

279

Toward laser driven proton medical accelerator  

Microsoft Academic Search

Towards our final goal, such as to establish the laser-driven proton accelerator for the medical application, one of the most important things to establish is to develop the proton transport system. In this continuous work, we demonstrate the focusing system of the laser-driven proton beam with permanent magnet qadrupoles (PMQs), with which a 2.4 MeV laser-driven proton beam, having a

M. Nishiuchi; H. Sakaki; T. Hori; K. Ogura; A. Yogo; A. S. Pirozhkov; A. Sagisaka; S. Orimo; M. Mori; H. Sugiyama; H. Kiriyama; M. Tampo; I. Daito; H. Okada; S. Kanazawa; M. Tanoue; T. Shimomura; Y. Nakai; H. Sasao; D. Wakai; F. Sasao; P. R. Bolton; H. Daido; S. Kawanishi; Y. Iseki; T. Nagafuchi; K. Maeda; K. Hanawa; T. Yoshiyuki; H. Souda; A. Noda

2010-01-01

280

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

281

Proton Solvation and Proton Mobility Department of Physical Chemistry and the Fritz Haber Research Center,  

E-print Network

. Three factors con­ tribute to differences in proton solvation energies: hydrogen­bond cleavage, changes­ mate, together with the activation energy for proton mobility, supports the 121 mechanism for proton mobility in which a protonated water monomer is transformed, by second­shell hydrogen­bond cleavage

Agmon, Noam

282

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. PMID:20533900

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

2011-01-01

283

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

284

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

285

Dose contribution from ?-electrons in proton radiotherapy  

Microsoft Academic Search

Abstract With the increasing number of cancer patients in the world today, there is a need for improved treatment methods. Proton radiotherapy is a promising field and there is an increasing interest in this treatment modality. Therefore the need for accurate treatment planning tools for proton radiotherapy is growing. When protons traverse matter they induce secondary electrons, so-called ?-electrons, via

Elanor Bäckman

286

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

287

Higher Twist Effects in Proton-Proton Collisions  

NASA Astrophysics Data System (ADS)

In this article, we investigate the contribution of the high twist Feynman diagrams to the large-pT pion production cross section in proton-proton collisions and we present the general formulae for the high and leading twist differential cross sections. The pion wave function where two non-trivial Gegenbauer coefficients a2 and a4 have been extracted from the CLEO data, two other pion model wave functions, P2, P3, the asymptotic and the Chernyak-Zhitnitsky wave functions are used in the calculations. The results of all the calculations reveal that the high twist cross sections, the ratios R, r, the dependence transverse momentum pT and the rapidity y of pion in the ?CLEO(x,Q2) wave function case is very close to the ?asy(x) asymptotic wave function case. It is shown that the high twist contribution to the cross section depends on the choice of the meson wave functions.

Ahmadov, A. I.; Boztosun, I.; Muradov, R. Kh.; Soylu, A.; Dadashov, E. A.

288

Imaging of brain metastases  

PubMed Central

Imaging plays a key role in the diagnosis of central nervous system (CNS) metastasis. Imaging is used to detect metastases in patients with known malignancies and new neurological signs or symptoms, as well as to screen for CNS involvement in patients with known cancer. Computed tomography (CT) and magnetic resonance imaging (MRI) are the key imaging modalities used in the diagnosis of brain metastases. In difficult cases, such as newly diagnosed solitary enhancing brain lesions in patients without known malignancy, advanced imaging techniques including proton magnetic resonance spectroscopy (MRS), contrast enhanced magnetic resonance perfusion (MRP), diffusion weighted imaging (DWI), and diffusion tensor imaging (DTI) may aid in arriving at the correct diagnosis. This image-rich review discusses the imaging evaluation of patients with suspected intracranial involvement and malignancy, describes typical imaging findings of parenchymal brain metastasis on CT and MRI, and provides clues to specific histological diagnoses such as the presence of hemorrhage. Additionally, the role of advanced imaging techniques is reviewed, specifically in the context of differentiating metastasis from high-grade glioma and other solitary enhancing brain lesions. Extra-axial CNS involvement by metastases, including pachymeningeal and leptomeningeal metastases is also briefly reviewed. PMID:23717792

Fink, Kathleen R.; Fink, James R.

2013-01-01

289

Proton Compton scattering in a unified proton-?+ model  

NASA Astrophysics Data System (ADS)

We develop a field-theoretic model for the description of the proton Compton scattering in which the proton and its excited state, the ?+ resonance, are described as parts of one multiplet with a single Rarita-Schwinger wave function. To describe the observed phenomena, it is necessary to incorporate both minimal and nonminimal couplings. The minimal coupling reflects the fact that the ?+ is a charged particle, and in this model the minimal coupling contributes also to the ?N? magnetic transition. The nonminimal couplings consist of five electromagnetic form factors, which are accessed at fixed and vanishing momentum transfer squared with real photons in the Compton scattering experiments, therefore it is possible to extract a somewhat well-determined set of optimal parameters which fit the data in the resonance region 140-450 MeV reasonably well. The crucial parameter which determines the ?N? transition amplitude and therefore the height of the resonance peak is equal to 1.83±0.03, in units of ?N. We find that this parameter is also the primary determinant of the contributions to the magnetic polarizability in this model. In the low-energy region up to 140 MeV, we separately fit the electric and magnetic polarizabilities while keeping the other parameters fixed, and obtain values in line with previous approaches. In addition to proton Compton scattering, the model is applicable to a broad range of processes in the few hundred MeV energy range, whenever the proton appears in some intermediate off-shell state.

Zhang, Yun; Savvidy, Konstantin

2013-12-01

290

Proton-Proton Weak Capture in Chiral Effective Field Theory  

NASA Astrophysics Data System (ADS)

The astrophysical S factor for proton-proton weak capture is calculated in chiral effective field theory over the center-of-mass relative-energy range 0-100 keV. The chiral two-nucleon potential derived up to next-to-next-to-next-to leading order is augmented by the full electromagnetic interaction including, beyond Coulomb, two-photon and vacuum-polarization corrections. The low-energy constants entering the weak current operators are fixed so as to reproduce the A=3 binding energies and magnetic moments and the Gamow-Teller matrix element in tritium ? decay. Contributions from S and P partial waves in the incoming two-proton channel are retained. The S factor at zero energy is found to be S(0)=(4.030±0.006)×10-23MeVfm2, with a P-wave contribution of 0.020×10-23MeVfm2. The theoretical uncertainty is due to the fitting procedure of the low-energy constants and to the cutoff dependence.

Marcucci, L. E.; Schiavilla, R.; Viviani, M.

2013-05-01

291

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

292

Proton Radius Puzzle in Hamiltonian Dynamics  

NASA Astrophysics Data System (ADS)

Relativistic lepton-proton bound-state eigenvalue equations for Hamiltonians derived from quantum field theory using second-order renormalization group procedure for effective particles, are reducible to two-body Schrödinger eigenvalue equations with the effective Coulomb potential that exhibits a tiny sensitivity to the characteristic momentum-scale of the bound system. The scale dependence is shown to be relevant to the theoretical interpretation of precisely measured lepton-proton bound-state energy levels in terms of a 4 % difference between the proton radii in muon-proton and electron-proton bound states.

G?azek, Stanis?aw D.

2014-11-01

293

Proton radiation damage in optical filter glass  

SciTech Connect

Samples of Schott BG-39 and Hoya CM-500 blue-green filter glass were subjected to proton radiation to determine their acceptability for spaceflight. Initial testing done with 2.7 MeV protons showed negligible change in optical transmittance with doses as high as 5.2 {times} 10{sup 14} protons per sq cm. Irradiation with protons of energy up to 63 MeV caused a significant reduction in transmittance in the Schott samples at doses of 5.3 {times} 10{sup 12} protons per sq cm, while negligible change occurred in the Hoya samples.

Grillot, P.N.; Rosenberg, W.J. (Lockheed Palo Alto Research Laboratories, 3251 Hanover Street, Palo Alto, California 94304 (US))

1989-10-15

294

Experimental status of proton decay  

NASA Astrophysics Data System (ADS)

Proton-decay experiments carried out in the Kolar GF, NUSEX, FREJUS, IMB, KAMIOKANDE, and HPW projects are reviewed, considering their implications for the fundamental physical problem of baryon nonconservation. Sample data are presented in extensive tables, diagrams, and graphs and briefly characterized. The overall event detection rate (about 100 events/ktonne yr at energies greater than 200 MeV), nucleon-decay-candidate rate (about 5 events/ktonne yr), and 'classic' two-track proton-decay rate (about 1 event/ktonne yr) are found to be consistent with theoretical predictions, and general limits of tau(p) greater than or equal to 5 x 10 to the 32nd/yr and tau(p) greater than or equal to 5 x 10 to the 31st/yr are estimated for 'classic' and neutrino-dominated decay modes, respectively.

van der Velde, J. C.

1986-03-01

295

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

296

Protons in rare earth oxides  

Microsoft Academic Search

The electrical conductivity of Gd2O3, Dy2O3 and Er2O3 nominally doped with 2 mol% CaO, has been measured as a function of PH2o (3 × 10?5 ? 2 × 10?2 atm) and PO2 (1–10?20 atm) in the temperature range 500–1200 °C. A defect structure with protons and oxygen vacancies compensating the acceptor dopants has been used to model the total conductivity

Yngve Larring; Truls Norby

1995-01-01

297

The ?(1520) photoproduction from proton  

NASA Astrophysics Data System (ADS)

The ?(1520) photoproduction from proton target is investigated within the effective Lagrangian method and well compared with the experimental data. The D13 state N(2120) plays the most important role among the nucleon resonances. Besides N(2120), a nucleon resonance [{5/ 2}-]2(2080) predicted by the constituent quark model is found also important to reproduce the experimental data. Other nucleon resonances give negligible contributions in the channel considered in this work.

He, Jun

2014-04-01

298

Proton Resonance Spectroscopy -- Final Report  

SciTech Connect

This report summarizes work supported by the DOE Grant DE-FG02-96ER40990 during its duration from June 1996 to May 2009. Topics studied include (1) statistical descriptions of nuclear levels and measurements of proton resonances relevant to such descriptions, including measurements toward a complete level scheme for 30P, (2) the development of methods to estimate the missing fraction of levels in a given measurement, and (3) measurements at HRIBF relevant to nuclear astrophysics.

Shriner, Jr, J F

2009-07-27

299

Proton Therapy of Uveal Melanomas  

Microsoft Academic Search

Background and Purpose:  Proton therapy for uveal melanoma provides high-conformal dose application to the target volume and, thus, an optimal saving of the organs at risk nearby. Treatment planning is done with the model-based treatment-planning system EYEPLAN. Tumor reconstruction is based only on a fundus composite, which often leads to an overestimation of the clinical target volume (CTV). The purpose was

Simone Marnitz; Dino Cordini; Rolf Bendl; Arne-Jörn Lemke; Jens Heufelder; Ioannis Simiantonakis; Heinz Kluge; Nikolaos E. Bechrakis; Michael H. Foerster; Wolfgang Hinkelbein

2006-01-01

300

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

301

Proton MRS in neurological disorders  

Microsoft Academic Search

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

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

1999-01-01

302

Antiquark distributions in the proton  

SciTech Connect

This is the final report of a three-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The study of quark and antiquark distributions in the nucleon has been a major endeavor in nuclear and particle physics. Results from a recent deep-inelastic scattering experiment suggest the surprising possibility that the up and down antiquark distributions in the proton are not symmetric. A sensitive and direct determination of the antiquark distributions in the proton can be made by comparing the Drell-Yan cross sections on hydrogen versus deuterium targets. The authors have proposed a new experiment (E866) at Fermilab to carry out such measurements. E866 has been taking data since September 1996. Preliminary results show that the apparatus is working very well. The authors anticipate having seven months of beam in 1997, which would allow them to achieve the sensitivities for a definitive measurement of flavor symmetry of sea quarks in the proton.

Brooks, M.; Carey, T.; Garvey, G. [and others

1997-07-01

303

High-Intensity Proton Accelerator  

SciTech Connect

Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

Jay L. Hirshfield

2011-12-27

304

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 PMID:16453830

Jahns, Peter; Polle, Andrea; Junge, Wolfgang

1988-01-01

305

Magnetic resonance detection of individual proton spins using quantum reporters.  

PubMed

We demonstrate a method of magnetic resonance imaging with single nuclear-spin sensitivity under ambient conditions. Our method employs isolated electronic-spin quantum bits (qubits) as magnetic resonance "reporters" on the surface of high purity diamond. These spin qubits are localized with nanometer-scale uncertainty, and their quantum state is coherently manipulated and measured optically via a proximal nitrogen-vacancy color center located a few nanometers below the diamond surface. This system is then used for sensing, coherent coupling, and imaging of individual proton spins on the diamond surface with angstrom resolution. Our approach may enable direct structural imaging of complex molecules that cannot be accessed from bulk studies. It realizes a new platform for probing novel materials, monitoring chemical reactions, and manipulation of complex systems on surfaces at a quantum level. PMID:25415924

Sushkov, A O; Lovchinsky, I; Chisholm, N; Walsworth, R L; Park, H; Lukin, M D

2014-11-01

306

Magnetic Resonance Detection of Individual Proton Spins Using Quantum Reporters  

NASA Astrophysics Data System (ADS)

We demonstrate a method of magnetic resonance imaging with single nuclear-spin sensitivity under ambient conditions. Our method employs isolated electronic-spin quantum bits (qubits) as magnetic resonance "reporters" on the surface of high purity diamond. These spin qubits are localized with nanometer-scale uncertainty, and their quantum state is coherently manipulated and measured optically via a proximal nitrogen-vacancy color center located a few nanometers below the diamond surface. This system is then used for sensing, coherent coupling, and imaging of individual proton spins on the diamond surface with angstrom resolution. Our approach may enable direct structural imaging of complex molecules that cannot be accessed from bulk studies. It realizes a new platform for probing novel materials, monitoring chemical reactions, and manipulation of complex systems on surfaces at a quantum level.

Sushkov, A. O.; Lovchinsky, I.; Chisholm, N.; Walsworth, R. L.; Park, H.; Lukin, M. D.

2014-11-01

307

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect

Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

None

2012-05-01

308

Principles and appraisal of combined images in NMR.  

PubMed

The interpretation of NMR images at Aberdeen is most often performed by the individual study of the proton density, difference, inversion recovery and T1 image. This report investigates the usefulness of presenting the information from a pair of images, in this instance the T1 and proton density images, in a single composite image. Information from the two images is combined such that the values from one image are represented by a change in hue (colour), and the values from the other by a change in luminance (intensity). To test the advantages of such combined images, a trial was run using a selection of prediagnosed abnormal brain scans. The information perceived as hue and luminance in the combined images was compared with that from separate conventional monochrome proton density and T1 images. Medical and nonmedical users were told the final diagnosis and were asked whether it was possible to see more, less, or the same information with regard to clinically relevant details in the structure of the abnormality and the image as whole. The results have revealed that for the majority of cases the combined image format can effectively represent the information normally contained in both the monochrome proton density and T1 images--thus speeding up the image viewing process. PMID:2601449

Wells, M G; Sharp, P F; Law, A N

1989-05-01

309

Monte Carlo calculated stopping-power ratios, water/air, for clinical proton dosimetry (50 - 250 MeV)  

NASA Astrophysics Data System (ADS)

Calculations of stopping power ratios, water to air, for the determination of absorbed dose to water in clinical proton beams using ionization chamber measurements have been undertaken using the Monte Carlo method. A computer code to simulate the transport of protons in water (PETRA) has been used to calculate images/0031-9155/42/1/006/img6.gif" ALIGN="TOP"/>-data under different degrees of complexity, ranging from values based on primary protons only to data including secondary electrons and high-energy secondary protons produced in nonelastic nuclear collisions. All numerical data are based on ICRU 49 proton stopping powers. Calculations using primary protons have been compared to the simple continuous slowing-down approximation (c.s.d.a.) analytical technique used in proton dosimetry protocols, not finding significant differences that justify elaborate Monte Carlo simulations except beyond the mean range of the protons (the far side of the Bragg peak). The influence of nuclear nonelastic processes, through the detailed generation and transport of secondary protons, on the calculated stopping-power ratios has been found to be negligible. The effect of alpha particles has also been analysed, finding differences smaller than 0.1% from the results excluding them. Discrepancies of up to 0.6% in the plateau region have been found, however, when the production and transport of secondary electrons are taken into account. The large influence of nonelastic nuclear interactions on proton depth - dose distributions shows that the removal of primary protons from the incident beam decreases the peak-to-plateau ratio by a large factor, up to 40% at 250 MeV. It is therefore emphasized that nonelastic nuclear reactions should be included in Monte Carlo simulations of proton beam depth - dose distributions.

Medin, Joakim; Andreo, Pedro

1997-01-01

310

Magnetic Resonance Imaging of coarse sediment  

Microsoft Academic Search

Non-destructive observation methods for coarse sediments are usually limited to two dimensions, for instance in opened cores or at the surface. We report a trial of a promising new method for three-dimensional imaging of gravelly sediments: Magnetic Resonance Imaging (MRI). MRI maps contrasts in density and relaxation properties of protons, which are very different for sediment and water in the

Maarten G. Kleinhans; Cécile R. L. P. N. Jeukens; Chris J. G. Bakker; Roy M. Frings

2008-01-01

311

The clinical case for proton beam therapy  

PubMed Central

Abstract Over the past 20 years, several proton beam treatment programs have been implemented throughout the United States. Increasingly, the number of new programs under development is growing. Proton beam therapy has the potential for improving tumor control and survival through dose escalation. It also has potential for reducing harm to normal organs through dose reduction. However, proton beam therapy is more costly than conventional x-ray therapy. This increased cost may be offset by improved function, improved quality of life, and reduced costs related to treating the late effects of therapy. Clinical research opportunities are abundant to determine which patients will gain the most benefit from proton beam therapy. We review the clinical case for proton beam therapy. Summary sentence Proton beam therapy is a technically advanced and promising form of radiation therapy. PMID:23083010

2012-01-01

312

Bragg peak prediction from quantitative proton computed tomography using different path estimates  

NASA Astrophysics Data System (ADS)

This paper characterizes the performance of the straight-line path (SLP) and cubic spline path (CSP) as path estimates used in reconstruction of proton computed tomography (pCT). The GEANT4 Monte Carlo simulation toolkit is employed to simulate the imaging phantom and proton projections. SLP, CSP and the most-probable path (MPP) are constructed based on the entrance and exit information of each proton. The physical deviations of SLP, CSP and MPP from the real path are calculated. Using a conditional proton path probability map, the relative probability of SLP, CSP and MPP are calculated and compared. The depth dose and Bragg peak are predicted on the pCT images reconstructed using SLP, CSP, and MPP and compared with the simulation result. The root-mean-square physical deviations and the cumulative distribution of the physical deviations show that the performance of CSP is comparable to MPP while SLP is slightly inferior. About 90% of the SLP pixels and 99% of the CSP pixels lie in the 99% relative probability envelope of the MPP. Even at an imaging dose of ~0.1 mGy the proton Bragg peak for a given incoming energy can be predicted on the pCT image reconstructed using SLP, CSP, or MPP with 1 mm accuracy. This study shows that SLP and CSP, like MPP, are adequate path estimates for pCT reconstruction, and therefore can be chosen as the path estimation method for pCT reconstruction, which can aid the treatment planning and range prediction of proton radiation therapy.

Wang, Dongxu; Rockwell Mackie, T.; Tomé, Wolfgang A.

2011-02-01

313

Dielectron Production in Proton-Nucleus Reactions  

E-print Network

M University, College Station, Texas 77843 (Received 15 August 1989) Dielectron production in proton-nucleus reactions is studied in the cascade model. In addition to production from the proton-neutron bremsstrahlung and the decay of delta, we have also... impor- tance of the various processes which contribute to its pro- duction. Theoretical work up to now has been concentrat- ed on dielectron production from the proton-neutron bremsstrahlung, 6' from the decay of delta, ' and from the pion...

Xiong, L.; Wu, J. Q.; Wu, Z. G.; Ko, Che Ming; Shi, J. H.

1990-01-01

314

An observation of proton-induced latchup  

NASA Technical Reports Server (NTRS)

Proton-induced latchup in a CMOS microprocessor known to have a very low heavy-ion-induced latchup threshold LET was observed. The latchup cross section vs. proton energy for three different bias conditions is displayed. Average measures of latchup current within an 11-ms window following the onset of latchup are provided, as a function of bias and incident proton energy. These data can be interpreted in terms of the present understanding of SEE phenomena.

Nichols, Donald K.; Coss, James R.; Watson, R. K.; Schwartz, Harvey R.; Pease, Ronald L.

1992-01-01

315

INFLUENCE OF WETTABILITY ON LIQUID WATER TRANSPORT IN GAS DIFFUSION LAYER OF PROTON EXCHANGE MEMBRANE FUEL  

E-print Network

INFLUENCE OF WETTABILITY ON LIQUID WATER TRANSPORT IN GAS DIFFUSION LAYER OF PROTON EXCHANGE to 3D systems, notably from binarised images of GDLs obtained by X ray microtomography. 1. INTRODUCTION that a detailed understanding of liquid water transport in the gas diffusion layer (GDL) is necessary

Paris-Sud XI, Université de

316

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

E-print Network

- curacy. To validate the use of this code, the cold-matter approximation for the scattering of fusion. K. Li, J. A. Frenje, F. H. Séguin, and R. D. Petrasso Plasma Science and Fusion Center fusion protons, respectively. From individual fluence images, it was found that the angular frequencies

317

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

318

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

319

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

320

Proton beam therapy in skull base pathology.  

PubMed

The optimal treatment of chordomas is maximal safe resection followed by radiation therapy. Data have shown that the use of protons has increased the local control of chordomas. Because of their physical properties, proton therapy has a sharp decline at its distal range, thereby minimizing collateral damage. However, this choice of radiation therapy has been limited based on the availability of resources. Given the high cost of proton facilities and improved techniques for other forms of radiation therapy, this article evaluates whether proton therapy is still superior to other radiation techniques in the treatment of chordomas. PMID:21978900

Alonso-Basanta, Michelle; Lustig, Robert A; Kennedy, David W

2011-10-01

321

Clinical CT-based calculations of dose and positron emitter distributions in proton therapy using the FLUKA Monte Carlo code  

Microsoft Academic Search

Clinical investigations on post-irradiation PET\\/CT (positron emission tomography\\/computed tomography) imaging for in vivo verification of treatment delivery and, in particular, beam range in proton therapy are underway at Massachusetts General Hospital (MGH). Within this project, we have developed a Monte Carlo framework for CT-based calculation of dose and irradiation-induced positron emitter distributions. Initial proton beam information is provided by a

K. Parodi; A. Ferrari; F. Sommerer; H. Paganetti

2007-01-01

322

Surveillance of Craniopharyngioma Cyst Growth in Children Treated With Proton Radiotherapy  

SciTech Connect

Purpose: Craniopharyngiomas are benign, slow-growing tumors that frequently contain a cystic component. Even with gross total resection, the cyst can reform and cause symptoms. Fluctuations in cyst volume during radiotherapy (RT) can affect treatment planning and delivery. The aim of this study was to report our experience with cyst enlargement during conformal proton RT for children with craniopharyngioma and to make recommendations regarding mid-treatment surveillance. Methods and Materials: Between January 2001 and August 2007, 24 children (aged {<=}18 years) underwent proton RT at the Massachusetts General Hospital for craniopharyngioma. For all 24 patients, tumor size on magnetic resonance imaging and/or computed tomography was measured before and after RT. Surveillance imaging was available for review on 17 patients. During RT, cyst growth was assessed to determine whether the treatment fields needed to be altered. Results: Of the 17 children who underwent repeat imaging during RT, 6 required intervention because of changes in cyst dimensions. Four patients (24%) had cyst growth beyond the original treatment fields, requiring enlargement of the treatment plan. One patient's treatment field was reduced after a decreased in cyst size. Cyst drainage was performed in another patient to avoid enlargement of the treatment fields. Conclusion: In patients undergoing highly conformal RT for craniopharyngiomas with cysts, routine imaging during treatment is recommended. Surveillance imaging should be performed at least every 2 weeks during proton RT in an attempt to avoid marginal failure. Craniopharyngiomas with large cystic components or enlargement during treatment might require weekly imaging.

Winkfield, Karen M. [Harvard Radiation Oncology Program, Harvard Medical School, Boston, MA (United States)], E-mail: kwinkfield@partners.org; Linsenmeier, Claudia; Yock, Torunn I. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Grant, P. Ellen [Department of Radiology, Massachusetts General Hospital, Boston, MA (United States); Yeap, Beow Y. Sc.D. [Department of Medicine, Massachusetts General Hospital, Boston, MA (United States); Butler, William E. [Department of Neurosurgery, Massachusetts General Hospital, Boston, MA (United States); Tarbell, Nancy J. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States)

2009-03-01

323

Proton aurora related to intervals of pulsations of diminishing periods  

E-print Network

Proton aurora related to intervals of pulsations of diminishing periods A. G. Yahnin,1 T. A precipitation produced by the cyclotron instability can be responsible for proton aurora. Indeed, the relationship between some types of proton aurora (proton spots and proton flashes) and pulsations in the Pc1

California at Berkeley, University of

324

Measurement of proton and anti-proton intensities in the Tevatron Collider  

SciTech Connect

This paper describes the techniques used to measure the intensities of the proton (p) and anti-proton ({bar p}) beams in the Tevatron collider. The systems provide simultaneous measurements of the intensity of the 36 proton and 36 antiproton bunches and their longitudinal profiles.

Stephen Pordes et al.

2003-06-04

325

Electron cloud simulations of a proton storage ring using cold proton bunches  

Microsoft Academic Search

Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs

Y. Sato; Jeffrey A Holmes; S. Y. Lee; R. Macek

2008-01-01

326

Proton form factors and two-photon exchange contribution to elastic electron-proton scattering  

E-print Network

Proton form factors and two-photon exchange contribution to elastic electron-proton scattering A. V . Differential cross section of the elastic ep scattering in one-photon exchange approximation gives) ]-1 is virtual photon polarization, M is the proton mass, is electron scattering angle. d0/d

327

What Really Prevents Proton Transport through Aquaporin? Charge Self-Energy versus Proton Wire Proposals  

Microsoft Academic Search

The nature of the control of water\\/proton selectivity in biological channels is a problem of a fundamental importance. Most studies of this issue have proposed that an interference with the orientational requirements of the so-called proton wire is the source of selectivity. The elucidation of the structures of aquaporins, which have evolved to prevent proton transfer (PT), provided a clear

Anton Burykin; Arieh Warshel

2003-01-01

328

Neutron-proton bremsstrahlung experiments  

NASA Astrophysics Data System (ADS)

It is well known that charged particles emit bremsstrahlung radiation when they are accelerated. Classical electron bremsstrahlung occurs when a photon is emitted by an electron accelerated in the field of a nucleus. The bremsstrahlung process also occurs in the scattering of nucleons, for which it is the lowest energy inelastic process that can occur. Like electron bremsstrahlung, nucleon-nucleon bremsstrahlung also requires the exchange of a virtual particle to conserve energy and momentum. In electron bremsstrahlung a virtual photon is exchanged but with two nucleons a meson can be exchanged. Unlike electron bremsstrahlung, in nucleon-nucleon bremsstrahlung the photon can originate from the exchanged meson. This exchange contribution has been shown in calculations to be a significant fraction of bremsstrahlung events. Thus bremsstrahlung serves as a probe of exchange currents in the nucleon-nucleon interaction. Because of a lack of a free neutron target or an intense neutron beam, few measurements of neutron-proton bremsstrahlung exist, each having poor statistical accuracy and poor energy resolution. The white neutron source at the Weapons Neutron Research (WNR) target area at the Los Alamos Meson Physics Facility (LAMPF) produces neutrons with energies from below 50 to above 400 MeV. Using time-of-flight techniques and a liquid hydrogen target, we are measuring the outgoing photons of energies up to 250 MeV at gamma ray angles of around 90 deg relative to the incident beam. Protons scattered at very forward angles are also detected in coincidence with the gamma rays.

Koster, J. E.; Nelson, R. O.; Schillaci, M. E.; Wender, S. A.; Mayo, D.; Brady, F. P.; Romero, J.; Krofcheck, D.; Blann, M.; Anthony, P.

329

Fluorescent Proton Sensors Based On Energy Transfer  

PubMed Central

Photophysical data and orbital energy levels (from electrochemistry) were compared for molecules with the same BODIPY acceptor part (red) and perpendicularly oriented xanthene or BODIPY donor fragments (green). Transfer of energy, hence the photophysical properties of the cassettes, including the pH dependant fluorescence in the xanthene containing molecules, correlates with the relative energies of the frontier orbitals in these systems. Intracellular sensing of protons is often achieved via sensors that switch off completely at certain pH values, but probes of this type are not easy to locate inside cells in their “off-state”. A communication from these laboratories (J. Am. Chem. Soc., 2009, 131, 1642 – 3) described how the energy transfer cassette 1 could be used for intracellular imaging of pH. This probe is fluorescent whatever the pH, but its exact photophysical properties are governed by the protonation-states of the xanthene donors. This work was undertaken to further investigate correlations between structure, photophysical properties, and pH for energy transfer cassettes. To achieve this, three other cassettes 2 – 4 were prepared another one containing pH-sensitive xanthene donors (2), and two “control cassettes” that each have two BODIPY-based donors (3 and 4). Both the cassettes 1 and 2 with xanthene-based donors fluoresce red under slightly acidic conditions (pH < ca 6), and green when the medium is more basic (> ca 7), whereas the corresponding cassettes with BODIPY donors give almost complete energy transfer regardless of pH. The cassettes that have BODIPY donors by contrast, show no significant fluorescence from the donor parts, but the overall quantum yields of the cassettes when excited at the donor (observation of acceptor fluorescence) are high (ca 0.6 and 0.9). Electrochemical measurements were performed to elucidate orbital energy level differences between the pH-fluorescence profiles of cassettes with xanthene donors, relative to the two with BODIPY donors. These studies confirm energy transfer in the cassettes is dramatically altered by analytes that perturb relative orbital levels. Energy transfer cassettes with distinct fluorescent donor and acceptor units provide a new, and potentially useful, approach to sensors for biomedical applications. PMID:21618970

Thivierge, Cliferson; Han, Junyan; Jenkins, Roxanne M.

2011-01-01

330

Effects of proton irradiation on glass filter substrates for the Rosetta mission.  

PubMed

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) instrument on board the Rosetta spacecraft, a misson of the European Space Agency to comet P/Wirtanen, includes two cameras for acquiring images of the comet. A set of interference filters deposited upon glass and fused-silica substrates will be added to the cameras for wavelength tuning. For this mission of more than 10/years in an interplanetary environment, the requirement of preserving the optical characteristics of the filters is a critical one. We checked the variation in the transmission of some filter substrates after proton irradiation that simulated the solar wind. To produce a situation that is representative of the interplanetary environment, we irradiated proton fluences at three energies: 1.5 x 10(11) protons/cm2 at 4 MeV, 1.9 x 10(10) protons/cm2 at 8 MeV, and 7.1 x 10(9) protons/cm2 at 18 MeV. Seven substrates were tested: three Suprasil-1; three colored glasses, namely, OG590, KG3, and RG9; and one quartz. In addition, two interference filters were checked. The results obtained show that Suprasil-1 is rather insensitive to this irradiation, whereas very small reductions in transmission, of the order of a few percent, occur for colored glasses. The transmission of these filters was remeasured 2 years after the irradiation, and showed a general decrease in the transmission reduction. PMID:12868837

Naletto, Giampiero; Boscolo, Alessio; Wyss, Jeffery; Quaranta, Alberto

2003-07-01

331

Strangeness production with protons and pions  

SciTech Connect

We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei.

Dover, C.B.

1993-01-01

332

Study of the polarization of cumulative protons  

SciTech Connect

The polarization of cumulative protons escaping from carbon, copper, and lead nuclei at an angle of 162/sup 0/ LS was measured at incident ..pi../sup -/ meson momenta of 1.5 to 5 GeV/c. An appreciable polarization (> or approx. =40%) of protons with momenta > or = 0.5 GeV/c was observed.

Burgov, N.A.; Vlasov, M.K.; Vorob'ev, L.S.; Gerzon, S.A.; Kiselev, Y.T.; Leksin, G.A.; Martem'yanov, A.N.; Pivnyuk, N.A.; Stolin, V.L.; Terekhov, Y.V.; Ushakov, V.I.; Chumakov, M.M.

1980-06-05

333

Physics at an upgraded Fermilab proton driver  

SciTech Connect

In 2004 the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future, primarily motivated by the recent exciting developments in neutrino physics. Over the last few months a physics study has developed the physics case for the Fermilab Proton Driver. The potential physics opportunities are discussed.

Geer, S.; /Fermilab

2005-07-01

334

Cadmium Biosorption Rate in Protonated Sargassum Biomass  

E-print Network

Cadmium Biosorption Rate in Protonated Sargassum Biomass J I N B A I Y A N G A N D B O H U M I L V Sargassum fluitans biomass was accompanied by the release of hydrogen protons from the biomass. The uptake the overall biosorption rate of cadmium ions in flat seaweed biomass particles. The overall biosorption

Volesky, Bohumil

335

The Proton Exchange Membrane (PEM) Fuel Cell  

NSDL National Science Digital Library

This page is an introduction to the Proton Exchange Membrane (PEM) fuel cell. It uses flash animation to explain in greater detail what the PEM fuel cell consists of and how it works. The website has an introductory animation which is followed by more in depth description of the proton exchange membrane fuel cell.

2012-09-13

336

Interplanetary proton fluence model - JPL 1991  

Microsoft Academic Search

We describe an updated predictive engineering model for the interplanetary fluence of protons with energies respectively greater than 1, 4, 10, 30, and 60 MeV. This has been the first opportunity to derive a model from a data set that has been collected in space over a long enough period of time to produce a valid sample of solar proton

J. Feynman; G. Spitale; J. Wang; S. Gabriel

1993-01-01

337

Structural Determinants of Proton Blockage in Aquaporins  

Microsoft Academic Search

Aquaporins are an important class of membrane channels selective for water and linear polyols but impermeable to ions, including protons. Recent computational studies have revealed that the relay of protons through the water-conduction pathway of aquaporin channels is opposed by a substantial free energy barrier peaking at the signature NPA motifs. Here, free-energy simulations and continuum electrostatic calculations are combined

Nilmadhab Chakrabarti; Benoît Roux; Régis Pomès

2004-01-01

338

Strangeness production with protons and pions  

SciTech Connect

We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei.

Dover, C.B.

1993-04-01

339

Physics at an Upgraded Fermilab Proton Driver  

E-print Network

In 2004 the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future, primarily motivated by the recent exciting developments in neutrino physics. Over the last few months a physics study has developed the physics case for the Fermilab Proton Driver. The potential physics opportunities are discussed.

S. Geer

2005-07-19

340

Nuclear magnetic resonance imaging with hyperpolarised helium-3  

Microsoft Academic Search

SummaryBackground Magnetic resonance imaging (MRI) relies on magnetisation of hydrogen nuclei (protons) of water molecules in tissue as source of the signal. This technique has been valuable for studying tissues that contain significant amounts of water, but biological settings with low proton content, notably the lungs, are difficult to image. We report use of spin-polarised helium-3 for lung MRI.Methods A

M Ebert; T Grossmann; W Heil; E. W Otten; R Surkau; M Thelen; M Leduc; P Bachert; M. V Knopp; L. R Schad

1996-01-01

341

An analytical solution to proton Bragg peak deflection in a magnetic field  

NASA Astrophysics Data System (ADS)

The role of MR imaging for image-guided radiation therapy (IGRT) is becoming more and more important thanks to the excellent soft tissue contrast offered by MRI. Hybrid therapy devices with integrated MRI scanners are under active development for x-ray therapy. The combination of proton therapy with MRI imaging has only been investigated at the theoretical or conceptual level. Of concern is the deflection of the proton beam in the homogeneous magnetic field. A previous publication has come to the conclusion that the impact of a 0.5 T magnetic field on the dose distribution for proton therapy is very small and lateral deflections stay well below 2 mm. The purpose of this study is to provide new insights into the effects of magnetic fields on a proton beam coming to rest in a patient. We performed an analytical calculation of the lateral deflection of protons with initial energies between 50 MeV and 250 MeV, perpendicular to the beam direction and the magnetic field. We used a power-law range-energy relationship and the Lorentz force in both relativistic and non-relativistic conditions. Calculations were done for protons coming to rest in water or soft tissue, and generalized to other uniform and non-uniform media. Results were verified by comparisons with numerical calculations and Monte Carlo simulations. A key result of our calculations is that the maximum lateral deflection at the end of range is proportional to the third power of the initial energy. Accordingly, due to the strong dependence on the energy, even a relatively small magnetic field of 0.5 T will cause a deflection of the proton beam by 1 cm at the end of range of a 200 MeV beam. The maximum deflection at 200 MeV is more than 10 times larger than that of a 90 MeV beam. Relativistic corrections of the deflection are generally small but they can become non-negligible at higher energies around 200 MeV and above. Contrary to previous findings, the lateral deflection of a proton beam can be significant (1 cm and above) even in relatively small magnetic fields of 0.5 T. However, the curved path of a proton beam in a magnetic field is easily predictable and it should be possible to account for this in treatment planning.

Wolf, Russell; Bortfeld, Thomas

2012-09-01

342

Proton conducting ceramic membranes for hydrogen separation  

DOEpatents

A multi-phase proton conducting material comprising a proton-conducting ceramic phase and a stabilizing ceramic phase. Under the presence of a partial pressure gradient of hydrogen across the membrane or under the influence of an electrical potential, a membrane fabricated with this material selectively transports hydrogen ions through the proton conducting phase, which results in ultrahigh purity hydrogen permeation through the membrane. The stabilizing ceramic phase may be substantially structurally and chemically identical to at least one product of a reaction between the proton conducting phase and at least one expected gas under operating conditions of a membrane fabricated using the material. In a barium cerate-based proton conducting membrane, one stabilizing phase is ceria.

Elangovan, S. (South Jordan, UT); Nair, Balakrishnan G. (Sandy, UT); Small, Troy (Midvale, UT); Heck, Brian (Salt Lake City, UT)

2011-09-06

343

Proton-sensitive custom SRAM detector  

SciTech Connect

Because of the recently discovered importance of protons to the upset of spaceborne electronics, a custom 4--bit SRAM chip was tested with protons. The SRAM was developed to determine the Single Event Upset hardness of CMOS latches using alpha particle measurements, by adjusting an offset voltage that reduces the charge required to upset a cell. The proton experiments were designed to observe both proton and silicon recoil produced ionization. The silicon recoils were generated by protons undergoing nuclear coulomb scattering. It was discovered that silicon recoil produced charge can be collected from very deep in the silicon substrate. This paper describes a calibration procedure for rhe SRAM detector. Source spectra were acquired with this chip by measuring the number of upset cells versus offset voltage.

Soli, G.A.; Blaes, B.R.; Buehler, M.G. (Jet Propulsion Lab., Pasadena, CA (United States))

1992-10-01

344

Pointing of laser-accelerated proton beams  

SciTech Connect

Small fluctuations in the acceleration sheath change the pointing of a proton beam accelerated from the rear side of a laser irradiated thin aluminum foil. The proton acceleration was produced with 40 fs pulses of a Ti:sapphire laser at an intensity of approximately 10{sup 19} W/cm{sup 2}. This observation has been made with a high spatial resolution Thomson spectrometer. The proton beam pointing has appeared stable in the energy range between the high energy cutoff (3 MeV) and 50% of this value. Deviations of the beam position at lower energies changes in a range of 0-3 mrad. The recorded pictures show wiggled and continuous proton traces which imply a release of the proton beam from the acceleration zone with a velocity chirp.

Schreiber, J.; Ter-Avetisyan, S.; Risse, E.; Kalachnikov, M.P.; Nickles, P.V.; Sandner, W.; Schramm, U.; Habs, D.; Witte, J.; Schnuerer, M. [MPI fuer Quantenoptik, Hans-Kopfermann-Str. 1, D 85748 Garching (Germany) and LMU Muenchen, Am Coulombwall 1, D 85748, Garching (Germany); Max Born Institut, Max Born Strasse 2a, D 12489 Berlin (Germany); Max Born Institut, Max Born Strasse 2a, D 12489 Berlin (Germany) and TU Berlin, Strasse des 17. Juni 135, D 10623 Berlin (Germany); LMU Muenchen, Am Coulombwall 1, D 85748, Garching (Germany); MPI fuer Quantenoptik, Hans-Kopfermann-Str. 1, D 85748 Garching (Germany); Max Born Institut, Max Born Strasse 2a, D 12489 Berlin (Germany)

2006-03-15

345

Proton solvation and transport in complex environments  

NASA Astrophysics Data System (ADS)

Proton solvation and transport is a central element in innumerable fundamental chemical processes, from seemingly simple acid-base reactions to the exceedingly complicated proton transport channels integral to cellular respiration. The uniqueness of the hydrated proton, relative to other simple monovalent cations, complicates our understanding of transport and solvation in even simple neat fluids. Fortunately, computer modeling has proven valuable in describing the microscopic mechanism and structures inherent in proton transport and solvation. This dissertation will describe the use of computer modeling to characterize proton solvation in pure and mixed liquids with an emphasis on the behavior near mixed dielectrics, as well as the transport mechanism and defining solvation structures in the more complicated surroundings of a hydrated electrolytic polymer.

Petersen, Matt K.

346

Proton Stereotactic Radiosurgery for the Treatment of Benign Meningiomas  

SciTech Connect

Purpose: Given the excellent prognosis for patients with benign meningiomas, treatment strategies to minimize late effects are important. One strategy is proton radiation therapy (RT), which allows less integral dose to normal tissue and greater homogeneity than photon RT. Here, we report the first series of proton stereotactic radiosurgery (SRS) used for the treatment of meningiomas. Methods and Materials: We identified 50 patients with 51 histologically proven or image- defined, presumed-benign meningiomas treated at our institution between 1996 and 2007. Tumors of <4 cm in diameter and located {>=}2 mm from the optic apparatus were eligible for treatment. Indications included primary treatment (n = 32), residual tumor following surgery (n = 8), and recurrent tumor following surgery (n = 10). The median dose delivered was 13 Gray radiobiologic equivalent (Gy[RBE]) (range, 10.0-15.5 Gy[RBE]) prescribed to the 90% isodose line. Results: Median follow-up was 32 months (range, 6-133 months). Magnetic resonance imaging at the most recent follow-up or time of progression revealed 33 meningiomas with stable sizes, 13 meningiomas with decreased size, and 5 meningiomas with increased size. The 3-year actuarial tumor control rate was 94% (95% confidence interval, 77%-98%). Symptoms were improved in 47% (16/ 34) of patients, unchanged in 44% (15/34) of patients, and worse in 9% (3/34) of patients. The rate of potential permanent adverse effects after SRS was 5.9% (3/51 patients). Conclusions: Proton SRS is an effective therapy for small benign meningiomas, with a potentially lower rate of long-term treatment-related morbidity. Longer follow-up is needed to assess durability of tumor control and late effects.

Halasz, Lia M., E-mail: lhalasz@partners.org [Harvard Radiation Oncology Program, Boston, Massachusetts (United States); Harvard Medical School, Boston, Massachusetts (United States); Bussiere, Marc R.; Dennis, Elizabeth R.; Niemierko, Andrzej [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Chapman, Paul H. [Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts (United States); Harvard Medical School, Boston, Massachusetts (United States); Loeffler, Jay S.; Shih, Helen A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Harvard Medical School, Boston, Massachusetts (United States)

2011-12-01

347

Proton Storage Ring control system  

SciTech Connect

When designing a control system for a new facility, one is faced with a bewildering array of electronic devices to use in the solution. There is, of course, no single correct solution because the constraints are Laboratory- and project-dependent. The major constraint applicable to the hardware choice for the Proton Storage Ring (PSR) control system was the limited manpower available for the design, development, and documentation of custom hardware. As a result, wherever possible, commercial components have been used that are based on recognized standards. The array of choice on the hardware side contrasts markedly with the absence of suitable commercial software products, and it is unfortunate that here there seems to be little prospect of change. The analysis of the overall system that follows will lead to a suitable hardware choice and a description of the software's structure. This paper is an overview, but more information is available.

Clout, P.; Bair, S.; Conley, A.; Ford, R.; Fuka, M.; Greene, N.

1983-01-01

348

SOFC based on proton conductors.  

SciTech Connect

We have fabricated a solid oxide fuel cell (SOFC) using BaCe0.8Y0.2Ox (BCY20) proton conductor as the electrolyte. An {approx} 10-{micro}m-thick dense BCY film was prepared on a porous Ni/BCYcermet (i.e., ceramic/metal composite) substrate by a dip coating process. The gas-permeable Ni/BCY cermet substrate backed with nickel mesh was used as the anode, and a platinum paste backed with platinum mesh served as the cathode. The current-voltage characteristics of the BCY-based SOFC were measured in the temperature range 450-800 C using wet air on the cathode side and hydrogen on the anode side. The power density of the fuel cell was {approx}90 and {approx}1500 mW/cm2 at 450 and 800 C,respectively.

(Balu) Balachandran, U.; Lee, Tae H.; Dorris, S. E.; Energy Systems

2007-01-01

349

Proton MR spectroscopy reveals lactate in infantile neuroaxonal dystrophy (INAD).  

PubMed

Changes of cerebral metabolites detected by proton MR spectroscopy in two cases of infantile neuroaxonal dystrophy are described. A 6 11/12-year-old boy and a girl (aged 4 1/12 years at the first and 5 2/12 years at the second examination) with infantile neuroaxonal dystrophy were investigated by magnetic resonance imaging and spectroscopy of the basal ganglia. The signal intensity of the cerebellar cortex was increased on T2-weighted, proton density, and fluid attenuated inversion recovery images. The long echo time (135 ms) spectra revealed the presence of lactate in the basal ganglia of both cases in all investigations. The N-acetylaspartate/creatine ratio was reduced in Case 1 and in the second investigation of Case 2. The choline/creatine ratio was always increased. As the diagnosis of infantile neuroaxonal dystrophy is made by a synopsis of various clinical, neuropathological, neurophysiological, and neuroradiological data, the presence of lactate in the basal ganglia spectra may help to narrow down the diagnosis and can support the decision to perform more invasive diagnostic procedures (such as biopsies of skin, conjunctiva or even of the brain). PMID:11414651

Mader, I; Krägeloh-Mann, I; Seeger, U; Bornemann, A; Nägele, T; Küker, W; Grodd, W

2001-04-01

350

First observation of two-proton radioactivity in {sup 48}Ni  

SciTech Connect

The decay of the extremely neutron-deficient {sup 48}Ni was studied by means of an imaging time-projection chamber, which allowed the recording of tracks of charged particles. The decays of six atoms were observed. Four of them clearly correspond to two-proton radioactivity, providing the first direct evidence for this decay mode in {sup 48}Ni. Two decays represent {beta}-delayed proton emission. The half-life of {sup 48}Ni is determined to be T{sub 1/2}=2.1{sub -0.4}{sup +1.4} ms.

Pomorski, M.; Pfuetzner, M.; Dominik, W.; Czyrkowski, H.; DaPbrowski, R.; Mazzocchi, C.; Mianowski, S. [Faculty of Physics, University of Warsaw, PL-00-681 Warsaw (Poland); Grzywacz, R. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Baumann, T.; Berryman, J. S.; Ginter, T.; Pereira, J.; Stolz, A. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Johnson, J.; Rykaczewski, K. P. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Kaminski, G. [Institute of Nuclear Physics PAN, PL-31-342 Krakow (Poland); Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Kuzniak, A. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Faculty of Physics, University of Warsaw, PL-00-681 Warsaw (Poland); Larson, N.; Liddick, S. N.; Suchyta, S. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (United States)

2011-06-15

351

Proton radiography of PBX 9502 detonation shock dynamics confinement sandwich test  

SciTech Connect

Recent results utilizing proton radiography (P-Rad) during the detonation of the high explosive PBX 9502 are presented. Specifically, the effects of confinement of the detonation are examined in the LANL detonation confinement sandwich geometry. The resulting detonation velocity and detonation shock shape are measured. In addition, proton radiography allows one to image the reflected shocks through the detonation products. Comparisons are made with detonation shock dynamics (DSD) and reactive flow models for the lead detonation shock and detonation velocity. In addition, predictions of reflected shocks are made with the reactive flow models.

Aslam, Tariq D [Los Alamos National Laboratory; Jackson, Scott I [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory

2009-01-01

352

FEASIBILITY OF POSITRON EMISSION TOMOGRAPHY OF DOSE DISTRIBUTION IN PROTON BEAM CANCER THERAPY.  

SciTech Connect

Proton therapy is a treatment modality of increasing utility in clinical radiation oncology mostly because its dose distribution conforms more tightly to the target volume than x-ray radiation therapy. One important feature of proton therapy is that it produces a small amount of positron-emitting isotopes along the beam-path through the non-elastic nuclear interaction of protons with target nuclei such as {sup 12}C, {sup 14}N, and {sup 16}O. These radioisotopes, mainly {sup 11}C, {sup 13}N and {sup 15}O, allow imaging the therapy dose distribution using positron emission tomography (PET). The resulting PET images provide a powerful tool for quality assurance of the treatment, especially when treating inhomogeneous organs such as the lungs or the head-and-neck, where the calculation of the dose distribution for treatment planning is more difficult. This paper uses Monte Carlo simulations to predict the yield of positron emitters produced by a 250 MeV proton beam, and to simulate the productions of the image in a clinical PET scanner.

BEEBE - WANG,J.J.; DILMANIAN,F.A.; PEGGS,S.G.; SCHLYEER,D.J.; VASKA,P.

2002-06-03

353

Coarse-grained potential analysis of neutron-proton and proton-proton scattering below the pion production threshold  

NASA Astrophysics Data System (ADS)

Using the ?-shell representation we present a successful fit to neutron-proton and proton-proton scattering data below the pion production threshold. A detailed overview of the theory necessary to calculate observables with this potential is presented. A new data selection process is used to obtain the largest mutually consistent data base. The analysis includes data within the years 1950 to 2013. Using 46 parameters we obtain ?2/Ndata=1.04 with Ndata=6713 including normalization data. Phase shifts with error bars are provided.

Pérez, R. Navarro; Amaro, J. E.; Arriola, E. Ruiz

2013-12-01

354

MR appearance of Virchow-Robin spaces along lenticulostriate arteries: Spin-echo and two-dimensional fast low-angle shot imaging  

SciTech Connect

To delineate the appearance of normal Virchow-Robin spaces on routine spin-echo images and demonstrate the lenticulostriate arteries within them with a flow-sensitive fast low-angle shot (FLASH) pulse sequence. Seventy subjects, free of cerebrovascular diseases and other neurologic disorders, ranging in age from 1 to 75 years, were examined. On a 1.5-T MR system, axial spin-echo images of 5 mm thickness were obtained in all subjects. In 45 of 70 subjects axial T2o-dimensional FLASH images of 3 mm thickness were contiguously images. On T1- and spin density-weighted images Virchow-Robin spaces were detected as small foci of cerebrospinal fluid intensity around the anterior commissure in all subjects (100%), and in the basal ganglia at the level of the foramen of Monro in 40 (57%). T2-weighted images equally showed Virchow-Robin spaces around the anterior commissure but were less sensitive than T1- and spin-density weighted images at the level of the foramen of Monro (14%). Virchow-Robin spaces identified on Tw-weighted images should be isointense with cerebrospinal fluid. However, one or two spaces in 11 younger subjects were hypointense relative to adjacent brain tissue. On FLASH images most Virchow-Robin spaces identified on spin-echo images were delineated as high-intensity foci, corresponding to lenticulostriate arteries. Normal Virchow-Robin spaces along the lenticulostriate arteries are frequently detected on spin-echo images. Their appearance, affected by the flow of associated lenticulostriate arteries, varies from hyper- to hypointensity to brain tissue on T2-weighted images. The two-dimensional FLASH sequence can demonstrate the flow of the arteries, thereby helping confirm that these are truly Virchow-Robin spaces. 19 refs., 2 figs.

Hirabuki, Norio; Fujita, Norihiko; Fujii, Keiko; Hashimoto, Tsutomu; Kozuka, Takahiro (Osaka Univ. Medical School (Japan))

1994-02-01

355

Kaon Pair Production in Proton--Proton Collisions  

E-print Network

The differential and total cross sections for kaon pair production in the pp->ppK+K- reaction have been measured at three beam energies of 2.65, 2.70, and 2.83 GeV using the ANKE magnetic spectrometer at the COSY-Juelich accelerator. These near-threshold data are separated into pairs arising from the decay of the phi-meson and the remainder. For the non-phi selection, the ratio of the differential cross sections in terms of the K-p and K+p invariant masses is strongly peaked towards low masses. This effect can be described quantitatively by using a simple ansatz for the K-p final state interaction, where it is seen that the data are sensitive to the magnitude of an effective K-p scattering length. When allowance is made for a small number of phi events where the K- rescatters from the proton, the phi region is equally well described at all three energies. A very similar phenomenon is discovered in the ratio of the cross sections as functions of the K-pp and K+pp invariant masses and the identical final state interaction model is also very successful here. The world data on the energy dependence of the non-phi total cross section is also reproduced, except possibly for the results closest to threshold.

Y. Maeda; M. Hartmann; I. Keshelashvili; S. Barsov; M. Büscher; M. Drochner; A. Dzyuba; V. Hejny; A. Kacharava; V. Kleber; H. R. Koch; V. Koptev; P. Kulessa; B. Lorentz; T. Mersmann; S. Mikirtytchiants; A. Mussgiller; M. Nekipelov; H. Ohm; D. Prasuhn; R. Schleichert; H. J. Stein; H. Ströher; Yu. Valdau; C. Wilkin; P. Wüstner

2007-10-09

356

Attosecond neutron Compton scattering from protons  

E-print Network

The effect of "anomalous" scattering of neutrons and electrons from protons in the electron-volt energy-transfer range is considered, and related experimental results are mentioned. A recent independent confirmation of this effect with a new data analysis procedure is presented. Due to the very short characteristic scattering time, there is no well defined separation of time scales of electronic and protonic motions. An outline of a proposed theoretical interpretation is presented, which is based on the fact that scattering protons represent \\textit{open} quantum systems, thus being subject to decoherence.

C. Aris Chatzidimitriou-Dreismann

2007-02-01

357

Space Environments and Effects: Trapped Proton Model  

NASA Technical Reports Server (NTRS)

An improved model of the Earth's trapped proton environment has been developed. This model, designated Trapped Proton Model version 1 (TPM-1), determines the omnidirectional flux of protons with energy between 1 and 100 MeV throughout near-Earth space. The model also incorporates a true solar cycle dependence. The model consists of several data files and computer software to read them. There are three versions of the mo'del: a FORTRAN-Callable library, a stand-alone model, and a Web-based model.

Huston, S. L.; Kauffman, W. (Technical Monitor)

2002-01-01

358

The perturbative proton form factor reexamined  

E-print Network

We recalculate the proton Dirac form factor based on the perturbative QCD factorization theorem which includes Sudakov suppression. The evolution scale of the proton wave functions and the infrared cutoffs for the Sudakov resummation are carefully chosen, such that the soft divergences from large coupling constants are diminished and perturbative QCD predictions are stablized. We find that the King-Sachrajda model for the proton wave function leads to results which are in better agreement with experimental data compared to the Chernyak-Zhitnitsky wave function.

Bijoy Kundu; Hsiang-nan Li; Jim Samuelsson; Pankaj Jain

1998-06-19

359

The perturbative proton form factor reexamined  

NASA Astrophysics Data System (ADS)

We recalculate the proton Dirac form factor based on the perturbative QCD factorization theorem, which includes Sudakov suppression. The evolution scale of the proton wave functions and the infrared cutoffs for the Sudakov re-summation are carefully chosen such that the soft divergences from large coupling constants are diminished and perturbative QCD predictions are stabilized. We find that the King Sachrajda model for the proton wave function leads to results which are in better agreement with experimental data than those from the Chernyak Zhitnitsky wave function.

Kundu, Bijoy; Li, Hsiang-Nan; Samuelsson, Jim; Jain, Pankaj

1999-05-01

360

Proton Radiography: Its uses and Resolution Scaling  

SciTech Connect

Los Alamos National Laboratory has used high energy protons as a probe in flash radiography for over a decade. In this time the proton radiography project has used 800 MeV protons, provided by the LANSCE accelerator facility at LANL, to diagnose over five-hundred dynamic experiments in support of stockpile stewardship programs as well as basic materials science. Through this effort significant experience has been gained in using charged particles as direct radiographic probes to diagnose transient systems. The results of this experience will be discussed through the presentation of data from experiments recently performed at the LANL pRad.

Mariam, Fesseha G. [Los Alamos National Laboratory

2012-08-09

361

Experimental tests of proton spin models  

SciTech Connect

We have developed models for the spin-weighted quark and gluon distribution in a longitudinally polarized proton. The model parameters are determined from current algebra sum rules and polarized deep-inelastic scattering data. A number of different scenarios are presented for the fraction of spin carried the constituent parton distributions. A possible long-range experimental program is suggested for measuring various hard scattering processes using polarized lepton and proton beams. With the knowledge gained from these experiments, we can begin to understand the parton contributions to the proton spin. 28 refs., 5 figs.

Ramsey, G.P. (Loyola Univ., New Orleans, LA (USA). Dept. of Physics Argonne National Lab., IL (USA). High Energy Physics Div.)

1989-11-03

362

Some Perspectives on Future Proton Radioactivity Experiments  

SciTech Connect

Understanding the phenomenon of one-proton emission is crucial for addressing the question of the location of the limits of observable nuclei. Much of the current understanding of this radioactive decay process has been developed and refined through measurements of proton emitters above Z = 50, where {approx}30 proton-emitting nuclei have already been discovered and studied. However, despite the great experimental and theoretical efforts over recent years, some important questions remain unanswered. Possibilities for future experiments to tackle some of these issues are considered.

Page, R. D. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool, L69 7ZE (United Kingdom)

2011-11-30

363

Extreme ultraviolet diagnostics of preformed plasma in laser-driven proton acceleration experiments  

NASA Astrophysics Data System (ADS)

Proton acceleration experiments involving a 5?m thick Ti foil target irradiation are carried out with the femtosecond Ti:sapphire laser JLITE-X. The plasma emission at 13.5nm is recorded employing concave multilayer mirrors, which image the front- and rear-side plasmas onto the sensitive surfaces of a fast x-ray photodiode and a backside-illuminated charge coupled device. Online time-of-flight fast-particle measurements are performed simultaneously with the extreme ultraviolet (XUV) measurements. A strong correlation is observed between the energetic proton signal and the spatiotemporal behavior of the XUV plasma emission. In particular, the longer duration of the prepulse-produced XUV plasma emission indicates a lowering of the maximum proton energy. This allows using the XUV emission for the diagnostics of the high-intensity laser-solid-target interaction.

Ragozin, Eugene N.; Pirozhkov, Alexander S.; Yogo, Akifumi; Ma, Jinglong; Ogura, Koichi; Orimo, Satoshi; Sagisaka, Akito; Mori, Michiaki; Li, Zhong; Nishiuchi, Mamiko; Daido, Hiroyuki

2006-12-01

364

Multispectral analysis of magnetic resonance images.  

PubMed

Magnetic resonance (MR) imaging systems produce spatial distribution estimates of proton density, relaxation time, and flow, in a two dimensional matrix form that is analogous to that of the image data obtained from multispectral imaging satellites. Advanced NASA satellite image processing offers sophisticated multispectral analysis of MR images. Spin echo and inversion recovery pulse sequence images were entered in a digital format compatible with satellite images and accurately registered pixel by pixel. Signatures of each tissue class were automatically determined using both supervised and unsupervised classification. Overall tissue classification was obtained in the form of a theme map. In MR images of the brain, for example, the classes included CSF, gray matter, white matter, subcutaneous fat, muscle, and bone. These methods provide an efficient means of identifying subtle relationships in a multi-image MR study. PMID:3964938

Vannier, M W; Butterfield, R L; Jordan, D; Murphy, W A; Levitt, R G; Gado, M

1985-01-01

365

Imaging pH phantoms using magnetization transfer technology at 1.5 Tesla  

Microsoft Academic Search

Magnetization transfer (MT) is an important source of contrast in magnetic resonance imaging (MRI), and is the basis of chemical exchange saturation transfer (CEST) imaging, which does not exist in our clinical MR scanner at 1.5 Tesla (T). Amide proton transfer (APT) imaging, a variant of CEST imaging, has been shown capable of detecting tissue acidosis during stroke at above

Maobin Wei; Zhiwei Shen; Gang Xiao; Renhua Wu; Qingchun Qiu; Yaowen Chen

2011-01-01

366

Proton Radiography Experiment to Visualize Gas Bubbles in Mercury  

SciTech Connect

An experiment to visualize small gas bubbles injected into mercury flowing in a test loop using proton radiography was conducted at the Los Alamos Neutron Science Center (LANSCE) in December 2006. Radiograph images of bubbles were obtained through two mercury thicknesses: 22 mm and 6 mm. Two jet bubblers and two needle bubblers were operated individually over a range of mercury flow speeds (0 - 1 m/s) and gas injection rates (0.1 - 500 sccm). Helium was most commonly used but Argon and Xenon were injected for limited test conditions. The smallest discernable bubbles were about 0.24 mm in diameter. Resolution was limited by image contrast which was notably improved with 6 mm of mercury thickness. Analysis of the radiograph images from jet bubbler conditions provided data on bubble size distribution and total bubble void fraction. In a few cases radiographs captured a large fraction of the injected gas, but generally 20 to 90% of injected gas was not captured in the images. In all more than 400 radiographs were made during the experiment in addition to several movies. Sound recordings of needle bubbler operation were also made and used to quantify bubble formation rate and size; these results are compared to theoretical predictions. This paper describes the experiment goals, scope and equipment; key results are presented and discussed.

Riemer, Bernie [ORNL; Felde, David K [ORNL; Wendel, Mark W [ORNL; Mariam, Fesseha G [Los Alamos National Laboratory (LANL); Merrill, Frank E [ORNL

2007-01-01

367

A Generalized Weizsacker-Williams Method Applied to Pion Production in Proton-Proton Collisions  

NASA Technical Reports Server (NTRS)

A new "Generalized" Weizsacker-Williams method (GWWM) is used to calculate approximate cross sections for relativistic peripheral proton-proton collisions. Instead of a mass less photon mediator, the method allows for the mediator to have mass for short range interactions. This method generalizes the Weizsacker-Williams method (WWM) from Coulomb interactions to GWWM for strong interactions. An elastic proton-proton cross section is calculated using GWWM with experimental data for the elastic p+p interaction, where the mass p+ is now the mediator. The resulting calculated cross sections is compared to existing data for the elastic proton-proton interaction. A good approximate fit is found between the data and the calculation.

Ahern, Sean C.; Poyser, William J.; Norbury, John W.; Tripathi, R. K.

2002-01-01

368

Initial clinical experience with scanned proton beams at the Italian National Center for Hadrontherapy (CNAO).  

PubMed

We report the initial toxicity data with scanned proton beams at the Italian National Center for Hadrontherapy (CNAO). In September 2011, CNAO commenced patient treatment with scanned proton beams within two prospective Phase II protocols approved by the Italian Health Ministry. Patients with chondrosarcoma or chordoma of the skull base or spine were eligible. By October 2012, 21 patients had completed treatment. Immobilization was performed using rigid non-perforated thermoplastic-masks and customized headrests or body-pillows as indicated. Non-contrast CT scans with immobilization devices in place and MRI scans in supine position were performed for treatment-planning. For chordoma, the prescribed doses were 74 cobalt grey equivalent (CGE) and 54 CGE to planning target volume 1 (PTV1) and PTV2, respectively. For chondrosarcoma, the prescribed doses were 70 CGE and 54 CGE to PTV1 and PTV2, respectively. Treatment was delivered five days a week in 35-37 fractions. Prior to treatment, the patients' positions were verified using an optical tracking system and orthogonal X-ray images. Proton beams were delivered using fixed-horizontal portals on a robotic couch. Weekly MRI incorporating diffusion-weighted-imaging was performed during the course of proton therapy. Patients were reviewed once weekly and acute toxicities were graded with the Common Terminology Criteria for Adverse Events (CTCAE). Median age of patients = 50 years (range, 21-74). All 21 patients completed the proton therapy without major toxicities and without treatment interruption. Median dose delivered was 74 CGE (range, 70-74). The maximum toxicity recorded was CTCAE Grade 2 in four patients. Our preliminary data demonstrates the clinical feasibility of scanned proton beams in Italy. PMID:23824124

Tuan, J; Vischioni, B; Fossati, P; Srivastava, A; Vitolo, V; Iannalfi, A; Fiore, M R; Krengli, M; Mizoe, J E; Orecchia, R

2013-07-01

369

In Vivo Detection of 15N-Coupled Protons in Rat Brain by ISIS Localization and Multiple-Quantum Editing  

NASA Astrophysics Data System (ADS)

Three-dimensional image-selected in vivo spectroscopy (ISIS) was combined with phase-cycled 1H- 15N heteronuclear multiple-quantum coherence (HMQC) transfer NMR for localized selective observation of protons J-coupled to 15N in phantoms and in vivo. The ISIS-HMQC sequence, supplemented by jump-return water suppression, permitted localized selective observation of 2-5 ?mol of [ 15N indole]tryptophan, a precursor of the neurotransmitter serotonin, through the 15N-coupled proton in 20-40 min of acquisition in vitro at 4.7 T. In vivo, the amide proton of [5- 15N]glutamine was selectively observed in the brain of spontaneously breathing 15NH 4+-infused rats, using a volume probe with homogeneous 1H and 15N fields. Signal recovery after three-dimensional localization was 72-82% in phantoms and 59 ± 4% in vivo. The result demonstrates that localized selective observation of 15N-coupled protons, with complete cancellation of all other protons except water, can be achieved in spontaneously breathing animals by the ISIS-HMQC sequence. This sequence performs both volume selection and heteronuclear editing through an addition/subtraction scheme and predicts the highest intrinsic sensitivity for detection of 15N-coupled protons in the selected volume. The advantages and limitations of this method for in vivo application are compared to those of other localized editing techniques currently in use for non-exchanging protons.

Kanamori, Keiko; Ross, Brian D.

1999-08-01

370

Improving the ?erenkov imaging technique with neural networks  

NASA Astrophysics Data System (ADS)

We have performed a systematic study in space and time of air ?erenkov images of photon and proton showers generated by Bartol-Haleakala simulation programs. The rejection power of the azwidth parameter exploited in the TeV discovery of the Crab Nebula is confirmed. We have used a neural net to search for other features discriminating the ?erenkov images of photons and protons and demonstrate how the efficiency of the imaging method can be improved. We also identified differences in (nanosecond) time-image correlations. We have found that the rejection of proton showers based on timing is not competitive with imaging. Our analysis and the associated programs are sufficiently general and flexible to be used for computer simulation of the threshold and photon recognition capability of any existing, projected, or conceived ?erenkov telescope.

Vazquez, R. A.; Halzen, F.; Zas, E.

1992-01-01

371

Phase coexistence in proton glass  

SciTech Connect

Proton glasses are crystals of composition M{sub 1{minus}x}(NW{sub 4}){sub x}W{sub 2}AO{sub 4}, where M = K,Rb, W = H,D, A = P,As. For x = 0 there is a ferroelectric (FE) transition, while for x = 1 there is an antiferroelectric (AFE) transition. In both cases, the transition is from a paraelectric (PE) state of tetragonal structure with dynamically disordered hydrogen bonds to an ordered state of orthorhombic structure. For an intermediate x range there is no transition, but the hydrogen rearrangements slow down, and eventually display nonergodic behavior characteristic of glasses. The authors and other have shown from spontaneous polarization, dielectric permittivity, nuclear magnetic resonance, and neutron diffraction experiments that for smaller x there is coexistence of ferroelectric and paraelectric phases, and for larger x there is coexistence of antiferroelectric and paraelectric phases. The authors present a method for analytically describing this coexistence, and the degree to which this coexistence is spatial or temporal.

Schmidt, V.H. [Montana State Univ., Bozeman, MT (United States). Physics Dept.; Trybula, Z. [Polish Academy of Sciences, Poznan (Poland). Inst. of Molecular Physics; Pinto, N.J. [Univ. of Puerto Rico, Humacao (Puerto Rico); Shapiro, S.M. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.

1996-11-01

372

[Proton therapy and particle accelerators].  

PubMed

Since the high energy accelerator plan was changed from a 40 GeV direct machine to a 12GeV cascade one, a 500 MeV rapid cycling booster synchrotron was installed between the injector linac and the 12 GeV main ring at KEK, National Lab. for High Energy Physics. The booster beams were used not only for injection to the main ring but also for medical use. Their energy was reduced to 250 MeV by a graphite block for clinical trial of cancer therapy. In 1970's, pi(-) or heavy ions were supposed to be promising. Although advantage of protons with Bragg Peak was pointed out earlier, they seemed effective only for eye melanoma at that time. In early 1980's, it was shown that they were effective for deep-seated tumor by Tsukuba University with KEK beams. The first dedicated facility was built at Loma Linda University Medical Center. Its synchrotron was made by Fermi National Accelerator Lab. Since a non-resonant accelerating rf cavity was installed, operation of the synchrotron became much easier. Later, innovation of the cyclotron was achieved. Its weight was reduced from 1,000 ton to 200 ton. Some of the cyclotrons are equipped with superconducting coils. PMID:24592677

Fukumoto, Sadayoshi

2012-01-01

373

Proton energy optimization and reduction for intensity-modulated proton therapy  

NASA Astrophysics Data System (ADS)

Intensity-modulated proton therapy (IMPT) is commonly delivered via the spot-scanning technique. To ‘scan’ the target volume, the proton beam is controlled by varying its energy to penetrate the patient’s body at different depths. Although scanning the proton beamlets or spots with the same energy can be as fast as 10–20?m?s?1, changing from one proton energy to another requires approximately two additional seconds. The total IMPT delivery time thus depends mainly on the number of proton energies used in a treatment. Current treatment planning systems typically use all proton energies that are required for the proton beam to penetrate in a range from the distal edge to the proximal edge of the target. The optimal selection of proton energies has not been well studied. In this study, we sought to determine the feasibility of optimizing and reducing the number of proton energies in IMPT planning. We proposed an iterative mixed-integer programming optimization method to select a subset of all available proton energies while satisfying dosimetric criteria. We applied our proposed method to six patient datasets: four cases of prostate cancer, one case of lung cancer, and one case of mesothelioma. The numbers of energies were reduced by 14.3%–18.9% for the prostate cancer cases, 11.0% for the lung cancer cases and 26.5% for the mesothelioma case. The results indicate that the number of proton energies used in conventionally designed IMPT plans can be reduced without degrading dosimetric performance. The IMPT delivery efficiency could be improved by energy layer optimization leading to increased throughput for a busy proton center in which a delivery system with slow energy switch is employed.

Cao, Wenhua; Lim, Gino; Liao, Li; Li, Yupeng; Jiang, Shengpeng; Li, Xiaoqiang; Li, Heng; Suzuki, Kazumichi; Zhu, X. Ronald; Gomez, Daniel; Zhang, Xiaodong

2014-10-01

374

Parameterized spectral distributions for meson production in proton-proton collisions  

NASA Technical Reports Server (NTRS)

Accurate semiempirical parameterizations of the energy-differential cross sections for charged pion and kaon production from proton-proton collisions are presented at energies relevant to cosmic rays. The parameterizations, which depend on both the outgoing meson parallel momentum and the incident proton kinetic energy, are able to be reduced to very simple analytical formulas suitable for cosmic ray transport through spacecraft walls, interstellar space, the atmosphere, and meteorites.

Schneider, John P.; Norbury, John W.; Cucinotta, Francis A.

1995-01-01

375

Proton energy optimization and reduction for intensity-modulated proton therapy.  

PubMed

Intensity-modulated proton therapy (IMPT) is commonly delivered via the spot-scanning technique. To 'scan' the target volume, the proton beam is controlled by varying its energy to penetrate the patient's body at different depths. Although scanning the proton beamlets or spots with the same energy can be as fast as 10-20?m?s(-1), changing from one proton energy to another requires approximately two additional seconds. The total IMPT delivery time thus depends mainly on the number of proton energies used in a treatment. Current treatment planning systems typically use all proton energies that are required for the proton beam to penetrate in a range from the distal edge to the proximal edge of the target. The optimal selection of proton energies has not been well studied. In this study, we sought to determine the feasibility of optimizing and reducing the number of proton energies in IMPT planning. We proposed an iterative mixed-integer programming optimization method to select a subset of all available proton energies while satisfying dosimetric criteria. We applied our proposed method to six patient datasets: four cases of prostate cancer, one case of lung cancer, and one case of mesothelioma. The numbers of energies were reduced by 14.3%-18.9% for the prostate cancer cases, 11.0% for the lung cancer cases and 26.5% for the mesothelioma case. The results indicate that the number of proton energies used in conventionally designed IMPT plans can be reduced without degrading dosimetric performance. The IMPT delivery efficiency could be improved by energy layer optimization leading to increased throughput for a busy proton center in which a delivery system with slow energy switch is employed. PMID:25295881

Cao, Wenhua; Lim, Gino; Liao, Li; Li, Yupeng; Jiang, Shengpeng; Li, Xiaoqiang; Li, Heng; Suzuki, Kazumichi; Zhu, X Ronald; Gomez, Daniel; Zhang, Xiaodong

2014-10-01

376

A compact electron cyclotron resonance proton source for the Paul Scherrer Institute's proton accelerator facility.  

PubMed

A compact electron cyclotron resonance proton source has been developed and installed recently at the Paul Scherrer Institute's high intensity proton accelerator. Operation at the ion source test stand and the accelerator demonstrates a high reliability and stability of the new source. When operated at a 10-12? mA net proton current the lifetime of the source exceeds 2000 h. The essential development steps towards the observed performance are described. PMID:21639497

Baumgarten, C; Barchetti, A; Einenkel, H; Goetz, D; Schmelzbach, P A

2011-05-01

377

Specificity of proton irradiation effects on polymers  

NASA Astrophysics Data System (ADS)

Protons affect the polymers mainly through scission and cross-linking of macromolecule chains. Ionization processes at proton non-elastic scattering define these effects. One of the most important problems of radiation physics and chemistry of polymers is the dependence of radiation effects on polymers on the kind of ionizing radiation or the LET problem. Analyze of such dependence for protons and some other kinds of radiation is presented. A detailed examination of 100 MeV proton collisions in polyethyleneterephtalate (PETP, trade mark Mylar) with negligible quantity of additive, on the base of the sample heat conductivity behavior revealed an important role of atomic displacements resulting from elastic nuclear scattering of low energy ions. Such damage of polymer molecules was not obtained for other examined types of radiation, in particular, for recoil nuclei at reactor neutron irradiation and for 60Co ?-irradiation.

Briskman, B. A.

2007-12-01

378

Memory device using movement of protons  

DOEpatents

An electrically written memory element is disclosed utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element. 19 figs.

Warren, W.L.; Vanheusden, K.J.R.; Fleetwood, D.M.; Devine, R.A.B.

1998-11-03

379

Secular variations in solar flare proton fluxes  

NASA Technical Reports Server (NTRS)

Proton fluences in contemporary solar-flare events (1965-82) are analyzed to obtain values of average flux and characteristic rigidity R0 (MV). Both proton fluences F (E greater than 10MeV) and R0 (in the energy interval 10-30 MeV) values for individual events follow log-normal distribution. Comparison of contemporary average flux and R0 values with long-term averaged values, based on lunar sample data, indicate that the ancient solar-flare proton spectra were harder compared to that observed in contemporary flares. The contemporary and long-term (greater than 10,000 yr) averaged fluxes are similar, although such a comparison may not be meaningful because the contemporary averages suffer from uncertainty due to statistics of a single event. The long-term average data suggests a secular variation in solar-flare activity with enhanced proton fluxes during the last 100,000 years.

Goswami, J. N.; Jha, R.; Lal, D.; Reedy, R. C.; Mcguire, R. E.

1983-01-01

380

Effects of Starfish on Geomagnetically Trapped Protons.  

National Technical Information Service (NTIS)

Measurements of geomagnetically-trapped, 55 MeV protons made before and after the detonation of the STARFISH nuclear device revealed that at low altitudes the flux increased considerably after the STARFISH burst. Theoretical analyses presented in this rep...

J. B. Cladis, G. T. Davidson, W. E. Francis, R. K. Jaggi, G. H. Nakano

1969-01-01

381

Proton-Conducting Metal-Organic Frameworks  

NASA Astrophysics Data System (ADS)

Vehicles powered by polymer electrolyte membrane (PEM) fuel cells are an exciting alternative to current fossil fuel technology. The membranes in these cells serve as both charge transporter, ferrying protons from the anode to the cathode, and gas diffusion barrier, preventing the backflow of oxygen to the anode. Currently, hydrated sulfonated polymers are the preferred material for these membranes. The presence of water, however, limits the operating temperature to 100 C, reducing the electrode kinetics and CO tolerance of the entire system. In an effort to increase the efficiency and operating temperature of these fuel cells, we are investigating the proton conductivity of new host/guest materials based on metal-organic frameworks (MOFs) loaded with imidazole. These thermally stable frameworks provide well-defined pores that accommodate imidazole networks and form proton-conducting pathways. Here, we will present the structure and proton dynamics of these materials as elucidated by elastic and inelastic neutron scattering measurements.

Ford, Jamie; Simmons, Jason; Yildirim, Taner

2010-03-01

382

Low energy neutron-proton interactions  

E-print Network

There have been few measurements of cross sections for neutron-proton scattering and radiative capture below 1 MeV. Those measurements which do exist are at a small number of energies and are often inconsistent with ...

Daub, Brian (Brian Hollenberg)

2012-01-01

383

Proton enhancement in an extended nanochannel.  

PubMed

Proton enhancement in an extended nanochannel is investigated by a continuum model consisting of three-dimensional Poisson-Nernst-Planck equations for the ionic mass transport of multiple ionic species with the consideration of surface chemistry on the nanochannel wall. The model is validated by the existing experimental data of the proton distribution inside an extended silica nanochannel. The proton enhancement behavior depends substantially on the background salt concentration, pH, and dimensions of the nanochannel. The proton enrichment at the center of the nanochannel is significant when the bulk pH is medium high (ca. 8) and the salt concentration is relatively low. The results gathered are informative for the development of biomimetic nanofluidic apparatuses and the interpretation of relevant experimental data. PMID:25295700

Atalay, Selcuk; Yeh, Li-Hsien; Qian, Shizhi

2014-11-01

384

Physics at a new Fermilab proton driver  

SciTech Connect

In 2004, motivated by the recent exciting developments in neutrino physics, the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future. At the end of 2004 the APS ''Study on the Physics of Neutrinos'' concluded that the future US neutrino program should have, as one of its components, ''A proton driver in the megawatt class or above and neutrino superbeam with an appropriate very large detector capable of observing Cp violation and measuring the neutrino mass-squared differences and mixing parameters with high precision''. The presently proposed Fermilab Proton Driver is designed to accomplish these goals, and is based on, and would help develop, Linear Collider technology. In this paper the Proton Driver parameters are summarized, and the potential physics program is described.

Geer, Steve; /Fermilab

2006-04-01

385

Design of a Gated Molecular Proton Channel  

SciTech Connect

The generation of an electrochemical pH gradient across biological membranes using energy from photosynthesis and respiration provides the universal driving force in cells for the production of adenosine triphosphate (ATP), the energy unit of life. Creating such an electrochemical potential requires the transportation of protons against a thermodynamic gradient. In biological proton pumps, chemical energy is used to induce protein conformational changes during each catalytic cycle where one or a few protons are pumped against a proton concentration gradient across the membrane. On the other hand, membrane channels also exist that mediate continuous particle exchange and may be switched between open and closed states. Being able to design nanochannels with similar functions would be of great importance for creating novel molecular devices with a wide range of applications such as molecular motors, fuel cells, rechargeable nanobatteries that provide energy to other nanomachines, and the generation of locally and temporally controlled pH jumps on microfluidic chips.

Gu, Wei; Zhou, Bo; Geyer, Tihamer; Hutter, Michael C.; Fang, Haiping; Helms, Volkhard H.

2011-01-17

386

Radiotherapy With Protons And Ion Beams  

SciTech Connect

The use of proton and ion beams has been proposed more than 60 years ago in 1946 by Robert Wilson. In 1955 the first patients were treated with proton beams in Berkeley. Since then radiotherapy with proton and ion beams has constantly been developed at research centers. Within the last decade, however, a considerable number of hospital based facilities came into operation. In this paper an overview over the basic physical and biological properties of proton and ion beams is given. The basic accelerator concepts are outlined and the design of treatment facilities is described. Then the medical physics aspects of the beam delivery, dosimetry and treatment planning are discussed before the clinical concepts are briefly reviewed.

Jaekel, Oliver [Heidelberg Ion Beam Therapy Center at the University Hospital Heidelberg, Im Neuenheimer Feld 450, 69120 Heidelberg (Germany); German Cancer Research Center, Dep. Medical Physics in Radiation Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

2010-04-26

387

Initial OTR measurements of 150 GeV protons in the Tevatron at FNAL  

SciTech Connect

Fermilab has developed standard optical transition radiation (OTR) detectors as part of its Run II upgrade program for measuring intense proton and antiproton beams. These detectors utilize radiation-hardened CID cameras to image the OTR and produce high-resolution two-dimensional beam profiles. One of these detectors has been installed in the Tevatron next to the new ionization profile monitor (IPM). Initial OTR measurements are presented for 150 GeV injected coalesced and uncoalesced proton bunches. OTR images are taken for one-turn and two-turn injections over an intensity range of 1.5e11 to 3.5e11 protons. Preliminary profile measurements give uncoalesced beam size sigmas of 1.0 mm horizontally by 0.7 mm vertically and coalesced beam size sigmas of 1.8 mm horizontally by 0.70 mm vertically. OTR images are also presented for changes in the Tevatron skew quadrupole magnet currents, which produce a rotation to the OTR image, and for changes to the Tevatron RF, which can be used to measure single-turn dispersion. Operational aspects of this detector for beam studies and Tevatron tuneup are also discussed.

Scarpine, V.E.; /Fermilab; Lumpkin, A.H.; /Argonne; Tassotto, G.R.; /Fermilab

2006-05-01

388

Dayside isotropic precipitation of energetic protons V. A. Sergeev1  

E-print Network

Dayside isotropic precipitation of energetic protons V. A. Sergeev1 , G. R. Bikkuzina1 , P. T precipitation of energetic protons on the nightside is caused by a non-adiabatic eect, namely pitch of isotropic proton precipitation on the dayside. Computations of proton scattering regions

Paris-Sud XI, Université de

389

SOLAR PROTONS, ALPHA PARTICLES, AND HEAVY NUCLEI IN NOVEMBER 1960  

Microsoft Academic Search

Energy spectra of solar protons and a particles were measured in the event fol- lowing the November 12, 1960, flare. The ratio of the abundance of protons to the abundance of a particles above the same rigidity was found to be 2. Spectra of protons, a particles, and medium nuclei were measured after the November 15, 1960, flare. The proton

E. P. Ney; W. A. Stein

1962-01-01

390

Development of Reversible Fuel Cell Systems at Proton Energy  

E-print Network

Development of Reversible Fuel Cell Systems at Proton Energy Everett Anderson NREL/DOE Reversible Fuel Cell Workshop 19 April 2011 #12;Development of Reversible Fuel Cell Systems at Proton Energy WorkshopNREL/DOE Reversible Fuel Cell Workshop Proton Energy Proton OnSite · Reflects developing business

391

Measurement of the inelastic proton-proton cross section with the ATLAS detector  

SciTech Connect

A measurement of the inelastic proton-proton cross-section at centre-of-mass energy of Central diffraction in proton-proton collisions at {radical}(s) = 7TeV using the ATLAS detector at the Large Hadron Collider is presented. Events are selected by requiring hits in scintillator counters mounted in the forward region of the ATLAS detector and the dataset corresponding to an integrated luminosity of 20{mu}b{sup -1}. In addition, the total cross-section is studied as a function of the rapidity gap size measured with the inner detector and calorimetry.

Zenis, Tibor [Comenius University Bratislava (Slovakia); Collaboration: ATLAS Collaboration

2013-04-15

392

Enhanced proton treatment in mouse tumors through proton irradiated nanoradiator effects on metallic nanoparticles  

NASA Astrophysics Data System (ADS)

The impact of protons on metallic nanoparticles (MNPs) produces the potent release of MNP-induced secondary electrons and characteristic x-rays. To determine the ability of secondary radiations to enhance proton treatment, the therapeutic irradiation of tumors was investigated in mice receiving 100-300 mg MNPs/kg intravenously prior to single dose, 10-41 Gy, proton irradiation. A proton beam was utilized to irradiate nanoparticles with a single Bragg peak set to occur inside a tumor volume (fully absorbed) or to occur after the beam had traversed the entire body. The dose-dependent increase in complete tumor regression (CTR) was 37-62% in the fully-absorbed irradiation group or 50-100% in the traversing irradiation group, respectively, compared with the proton-alone control mice (p < 0.01). One year survival was 58-100% versus 11-13% proton alone. The dose-dependent increase of intracellular reactive oxygen species level was 12-36% at 10 Gy compared with the proton-alone control cell. Therapeutic effective drug concentration that led to 100% CTR with a proton dose of 31 Gy was measured either 41 µg Au/g tissue or 59 µg Fe/g tissue. MNP-based proton treatment increased not only percent CTR and survival in vivo but also ROS generation in vitro, suggesting tumor dose enhancement from secondary radiation as one potent pathway of therapeutic enhancement.

Kim, Jong-Ki; Seo, Seung-Jun; Kim, Hong-Tae; Kim, Ki-Hong; Chung, Myung-Hwan; Kim, Kye-Ryung; Ye, Sung-Jun

2012-12-01

393

Development of 1 MV tandem proton accelerator  

Microsoft Academic Search

A 1MV Tandem Proton Accelerator is being developed for the industrial applications such as high-energy implantation and explosive detection. The proton accelerator consists of a 10 mA negative hydrogen ion source, two Einzel lenses, accelerating tubes, a gas stripper, a 1MV 30 mA Cockroft-Walton high voltage power supply, vacuum pumping system, and a high pressure insulating gas system. The large

Y. S. Cho; W. S. Song; B. H. Choi

2001-01-01

394

Neutron-proton pairs in nuclei  

E-print Network

A review is given of attempts to describe nuclear properties in terms of neutron--proton pairs that are subsequently replaced by bosons. Some of the standard approaches with low-spin pairs are recalled but the emphasis is on a recently proposed framework with pairs of neutrons and protons with aligned angular momentum. The analysis is carried out for general $j$ and applied to $N=Z$ nuclei in the $1f_{7/2}$ and $1g_{9/2}$ shells.

P. Van Isacker

2013-10-18

395

Periods of High Intensity Solar Proton Flux  

NASA Technical Reports Server (NTRS)

Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.

2012-01-01

396

Proton pump of clathrin-coated vesicles  

Microsoft Academic Search

Clathrin-coated vesicles were prepared from bovine brain catalyze ATP-driven proton translocation and a ³²Pi-ATP exchange reaction. N-ethylmaleimide (NEM) at 1 mM and dicyclohexylcarbodiimide (DCCD) at 0.5 mM inhibit the pump completely, whereas neither vanadate, efrapeptin, NaNâ, nor mitochondrial ATPase inhibitor has an effect. The coated vesicle proton pump is characterized by ATP specificity. dATP, but no other nucleotide, can replace

1985-01-01

397

Gas-Phase Protonation Thermochemistry of Adenosine  

Microsoft Academic Search

The goal of this work was to obtain a detailed insight on the gas-phase protonation energetic of adenosine using both mass spectrometric experiments and quantum chemical calculations. The experimental approach used the extended kinetic method with nanoelectrospray ionization and collision-induced dissociation tandem mass spectrometry. This method provides experimental values for proton affinity, PA(adenosine) ) 979 ( 1 kJ ·mol-1, and

David Touboul; Guy Bouchoux; Renato Zenobi

2008-01-01

398

Proton resonance assignments of horse ferricytochrome c  

Microsoft Academic Search

Two-dimensional nuclear magnetic resonance spectroscopy (2D NMR) was used to obtain extensive resonance assignments in the ¹H NMR spectrum of horse ferricytochrome c. Assignments were made for the main-chain and C{sub β} protons of 102 residues (all except Pro-44 and Gly-84) and the majority of side-chain protons. As starting points for the assignment of the oxidized protein, a limited set

A. Joshua Wand; Deena L. Di Stefano; S. W. Englander

1989-01-01

399

The Francis H. Burr Proton Therapy Center  

NASA Astrophysics Data System (ADS)

The Francis H. Burr Proton Therapy Center (FHBPTC) is one of the first hospital-based proton therapy (PT) facilities. Its development was the natural evolution of several decades of PT experience of the Massachusetts General Hospital treating patients at the Harvard Cyclotron Laboratory. The operations of the FHBPTC reflect the combined missions of patient care, clinical and physics research, technological developments, and education. This chapter will discuss aspects of the history, evolution, and performance of this unique PT center.

Flanz, Jay; Kooy, Hanne; DeLaney, Thomas F.

400

Electron/proton spectrometer certification documentation analyses  

NASA Technical Reports Server (NTRS)

A compilation of analyses generated during the development of the electron-proton spectrometer for the Skylab program is presented. The data documents the analyses required by the electron-proton spectrometer verification plan. The verification plan was generated to satisfy the ancillary hardware requirements of the Apollo Applications program. The certification of the spectrometer requires that various tests, inspections, and analyses be documented, approved, and accepted by reliability and quality control personnel of the spectrometer development program.

Gleeson, P.

1972-01-01

401

From neutrino masses to proton decay  

NASA Astrophysics Data System (ADS)

Current theoretical and experimental issues are reviewed in the light of the recent SuperKamiokande discovery. By using quark-lepton symmetries, derived from Grand Unification and/or string theories, we show how to determine the necessary neutrino parameters. In addition, the seesaw neutrino masses set the scale for the proton decay operators by "measuring" the standard model cut-off. The SuperKamiokande values suggest that proton decay is likely to be observed early in the XXIst Century.

Ramond, P.

2000-08-01

402

Microspectrofluorometry of the protonation state of ellipticine, an antitumor alkaloid, in single cells.  

PubMed Central

The protonation state and intracellular distribution of ellipticine were investigated in single human mammary T47D cells by confocal laser microspectrofluorimetry. In the cell nucleus, only the protonated form of ellipticine was detected as a direct consequence of its apparent pK increase upon DNA binding. Both protonated and neutral forms were present in the aqueous cytoplasm, where the pH is close to the drug pK. When cells were incubated in high concentrations of K+, a condition that depolarizes the plasma membrane potential, ellipticine cellular accumulation was reduced. In the cytoplasm, ellipticine was mainly bound to mitochondria, and its protonation equilibrium was shifted toward the neutral form. The fluorescence spectrum of ellipticine bound to mitochondria was insensitive to valinomycin, whereas it was markedly shifted toward the protonated form after carbonyl cyanide p-trifluoromethoxy-phenylhydrazone or nigericin addition. Similar studies with ellipticine bound to isolated mitochondria suggest that it behaves as