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1

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

Microsoft Academic Search

Modern neurosurgery takes advantage of magnetic resonance images (MRI) of a patient's cerebral anatomy and vasculature for planning before surgery and guid- ance during the procedure. Dual echo acquisitions are often performed that yield proton density (PD) and T2-weighted images to evaluate edema near a tumor or lesion. In this paper we develop a novel geometric flow for segmenting vasculature

Maxime Descoteaux; D. Louis Collins; Kaleem Siddiqi

2008-01-01

2

23 Na microscopy of the mouse heart in vivo using density-weighted chemical shift imaging  

Microsoft Academic Search

The mouse has become an important animal model for human cardiac disease, and the development of techniques for non-invasive imaging of the mouse heart in vivo is, therefore, of great potential interest. Previous magnetic resonance imaging studies have concentrated on pathologically induced changes in cardiac structure and dynamics by acquiring proton images. Further information can be gained by studying cardiac

T. Neuberger; A. Greiser; M. Nahrendorf; P. M. Jakob; C. Faber; A. G. Webb

2004-01-01

3

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

PubMed Central

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

2013-01-01

4

Short tau inversion recovery and proton density-weighted fat suppressed sequences for the evaluation of osteoarthritis of the knee with a 1.0 T dedicated extremity MRI: development of a time-efficient sequence protocol  

Microsoft Academic Search

Aim of this study was to develop a time-efficient sequence protocol for a 1.0 T dedicated MR system to be used for whole-organ scoring of osteoarthritis (OA). Thirty-four knees were examined using a protocol that included fat suppressed fast spin echo proton density weighted sequences (PDFS) in three planes plus a coronal STIR sequence. Two radiologists scored each knee by

Frank W. Roemer; Ali Guermazi; John A. Lynch; Charles G. Peterfy; Michael C. Nevitt; Nita Webb; Jing Li; Andreas Mohr; Harry K. Genant; David T. Felson

2005-01-01

5

Usefulness of positron-emission tomographic images after proton therapy  

Microsoft Academic Search

Purpose: To examine the positron emission tomography (PET) image obtained after proton irradiation and investigate the usefulness of the image for confirmation of the irradiated volume in proton radiotherapy (RT).Methods and Materials: A homogenous phantom was irradiated separately by carbon-ion and proton beams and the images obtained were compared. The PET images of cancer patients just after proton RT were

Yoshio Hishikawa; Kazufumi Kagawa; Masao Murakami; Hiroto Sakai; Takashi Akagi; Mitsuyuki Abe

2002-01-01

6

Proton Magnetic Resonance Imaging of Flowing Blood.  

NASA Astrophysics Data System (ADS)

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

Du, Leila Ning-Zhi

1987-09-01

7

Proton MR spectroscopic imaging of the striatum in Parkinson's disease  

Microsoft Academic Search

Assess the feasibility of proton MR spectroscopic imaging (1H-MRSI) of the striatum (putamen and caudate nucleus) in patients with Parkinson's disease and evaluate striatal neuronal density. Proton MRSI of the striatum and thalamus with 2 cc spatial resolution was performed in 10 patients with Parkinson's disease, 1 patient with atypical parkinsonism, and 13 control subjects. Single voxel proton MR spectra

Calvin J. Cruz; Michael J. Aminoff; Dieter J. Meyerhoff; Steve H. Graham; Michael W. Weiner

1997-01-01

8

Imaging intelligence with proton magnetic resonance spectroscopy  

PubMed Central

Proton magnetic resonance spectroscopy (1H-MRS) is a technique for the assay of brain neurochemistry in vivo. N-acetylaspartate (NAA), the most prominent metabolite visible within the 1H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA–cognition relationships, particularly whether such relationships are moderated by sex, or tissue type (gray or white matter). We administered standard measures of intelligence to 63 young, healthy subjects and obtained spectroscopic imaging data within a slab of tissue superior to the lateral ventricles. We found that lower NAA within right anterior gray matter predicted better performance VIQ (F=6.83, p=.011, r2=.10), while higher NAA within the right posterior gray matter region predicted better PIQ (F=8.175, p=.006, r2=.12). These findings add to the small but growing body of literature linking brain biochemistry to intelligence in normal healthy subjects using 1H-MRSI.

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

2009-01-01

9

Total variation superiorization schemes in proton computed tomography image reconstruction  

Microsoft Academic Search

Purpose: Iterative projection reconstruction algorithms are currently the preferred reconstruction method in proton computed tomography (pCT). However, due to inconsistencies in the measured data arising from proton energy straggling and multiple Coulomb scattering, noise in the reconstructed image increases with successive iterations. In the current work, we investigated the use of total variation superiorization (TVS) schemes that can be applied

S. N. Penfold; R. W. Schulte; Y. Censor; A. B. Rosenfeld

2010-01-01

10

Total variation superiorization schemes in proton computed tomography image reconstruction  

Microsoft Academic Search

Purpose: Iterative projection reconstruction algorithms are currently the\\u000apreferred reconstruction method in proton computed tomography (pCT). However,\\u000adue to inconsistencies in the measured data arising from proton energy\\u000astraggling and multiple Coulomb scattering, noise in the reconstructed image\\u000aincreases with successive iterations. In the current work, we investigated the\\u000ause of total variation superiorization (TVS) schemes that can be applied

S. N. Penfold; R. W. Schulte; Y. Censor; A. B. Rosenfeld

2010-01-01

11

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

12

Observation of dayside subauroral proton flashes with IMAGE-FUV.  

NASA Astrophysics Data System (ADS)

The IMAGE-FUV experiment onboard the IMAGE satellite includes three imagers: the WIC and SI13 instruments produce a global scale imaging of the N_2 LBH wavelength range and of the OI 130.4 nm emission respectively, and are thus devoted to the study of the electron aurora. The third imager, SI12, remotely senses the Doppler shifted Lyman-alpha emission, that is solely due to the proton aurora, at the global scale. We present here a new auroral feature observed with the SI12 instrument, consisting of sudden dayside subauroral injections of protons at magnetic latitudes sometimes lower than 60^o MLAT, at the foot of field lines of L shells as low as 4 RE. The extension of the feature in magnetic local time is variable and cases extending from ˜0700 to ˜1500 MLT were seen. The relaxation time of these features will be discussed. Most of these dayside subauroral proton flashes are found to be related to sudden solar wind dynamic pressure pulses, but a few counter examples were found. The relationship with the IMF orientation is investigated.

Hubert, B.; Gérard, J.-C.; Fuselier, S. A.; Mende, S. B.

2003-04-01

13

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

Microsoft Academic Search

Conventional proton density and T2-weighted spin-echo images are susceptible to motion induced artifact, which is exacerbated by lipid signals. Gradient moment nulling can reduce motion artifact but lengthens the minimum TE, degrading the proton density contrast. We designed a pulse sequence capable of optimizing proton density and T2-weighted contrast while suppressing lipid signals and motion induced artifacts. Proton density weighting

Simon Vinitski; Donald G. Mitchell; Jerzy Szumowski; D. Lawrence Burk Jr.; Matthew D. Rifkin

1990-01-01

14

Electron and proton shock aurora observed by IMAGE-FUV  

NASA Astrophysics Data System (ADS)

The FUV instrument on the IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) satellite monitors the aurora in three different spectral regions. The Wideband Imaging Camera (WIC) observes the molecular N_2 LBH and the atomic NI emissions at 140-180 nm. The two channels of the Spectrographic Imager (SI) observe the Doppler shifted Lyman-? emission at 121.8 nm due to precipitating protons (SI12) and the electron auroral emission of OI at 135.6 nm (SI13). Three simultaneous snapshots are recorded each 2 minutes. In this study, the FUV instrument allows a global viewing of the aurora with a high temporal resolution both in proton and electron. It is used to study the shock aurora resulting from the disturbance caused by the arrival of a coronal mass ejection on the front of the magnetosphere. A comparison between electron and proton injection features at global scale is performed for different isolated events with positive and negative interplanetary B_z. A correlation with IMF and solar wind parameters is presented as well as a description of the magnetosphere morphology given by the Tsyganenko model in the shock aurora period.

Meurant, M.; Gérard, J. C.; Hubert, B.; Coumans, V.; Blockx, C.

2003-04-01

15

An adaptive density-weighted contrast enhancement filter for mammographic breast mass detection  

SciTech Connect

This paper presents a novel approach for segmentation of suspicious mass regions in digitized mammograms using a new adaptive density-weighted contrast enhancement (DWCE) filter in conjunction with Laplacian-Gaussian (LG) edge detection. The DWCE enhances structures within the digitized mammogram so that a simple edge detection algorithm can be used to define the boundaries of the objectives. Once the object boundaries are known, morphological features are extracted and used by a classification algorithm to differentiate regions within the image. This paper introduces the DWCE algorithm and presents results of a preliminary study based on 25 digitized mammograms with biopsy proven masses. It also compares morphological feature classification based on sequential thresholding, linear discriminant analysis, and neural network classifiers for reduction of false-positive detections.

Petrick, N.; Chan, H.P.; Sahiner, B. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Radiology; Wei, D. [Univ. of Chicago, IL (United States). Dept. of Radiology

1996-02-01

16

Total variation superiorization schemes in proton computed tomography image reconstruction  

PubMed Central

Purpose: Iterative projection reconstruction algorithms are currently the preferred reconstruction method in proton computed tomography (pCT). However, due to inconsistencies in the measured data arising from proton energy straggling and multiple Coulomb scattering, the noise in the reconstructed image increases with successive iterations. In the current work, the authors investigated the use of total variation superiorization (TVS) schemes that can be applied as an algorithmic add-on to perturbation-resilient iterative projection algorithms for pCT image reconstruction. Methods: The block-iterative diagonally relaxed orthogonal projections (DROP) algorithm was used for reconstructing GEANT4 Monte Carlo simulated pCT data sets. Two TVS schemes added on to DROP were investigated; the first carried out the superiorization steps once per cycle and the second once per block. Simplifications of these schemes, involving the elimination of the computationally expensive feasibility proximity checking step of the TVS framework, were also investigated. The modulation transfer function and contrast discrimination function were used to quantify spatial and density resolution, respectively. Results: With both TVS schemes, superior spatial and density resolution was achieved compared to the standard DROP algorithm. Eliminating the feasibility proximity check improved the image quality, in particular image noise, in the once-per-block superiorization, while also halving image reconstruction time. Overall, the greatest image quality was observed when carrying out the superiorization once per block and eliminating the feasibility proximity check. Conclusions: The low-contrast imaging made possible with TVS holds a promise for its incorporation into future pCT studies.

Penfold, S. N.; Schulte, R. W.; Censor, Y.; Rosenfeld, A. B.

2010-01-01

17

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

18

Dayside Proton Aurora: Comparisons Between Global MHD-Simulations and Image Observations.  

National Technical Information Service (NTIS)

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 I...

J. Berchem S. A. Fuselier S. Petrinec

2004-01-01

19

Toward proton MR spectroscopic imaging of stimulated brain function  

SciTech Connect

With the objective of complementing local cerebral metabolic studies of PET, and as a prelude to spectroscopic imaging, the authors have performed the first localized proton spectroscopic study of the stimulated human auditory cortex. Water suppressed localized spectroscopy (voxel size 3cm [times] 3cm [times] 3cm enclosing the auditory cortex, Te = 272ms, Tr = 3s) was performed on a 1.5T MRI/MRS system and spectra were acquired during stimulation with a 1kHz tone presented at 2Hz. Measurements were conducted for 30-40 min with a temporal resolution of 3.2 min (64 averages per time block). Results included in this paper from six subjects show a lactate peak which increases during stimulation compared to baseline values. These results suggest an increase in anaerobic glycolysis during stimulation and provide unique and valuable information that should complement glucose metabolism and flood flow studies of PET.

Singh, M. (University of Southern California, Los Angeles, CA (United States). Dept. of Radiology)

1992-08-01

20

Correlation of proton MR spectroscopy and diffusion tensor imaging.  

PubMed

Proton magnetic resonance spectroscopy ((1)H-MRS) provides indices of neuronal damage. Diffusion tensor imaging (DTI) relates to water diffusivity and fiber tract orientation. A method to compare (1)H-MRS and DTI findings was developed, tested on phantom and applied on normal brain. Point-resolved spectroscopy (T(R)/T(E)=1500/135) was used for chemical shift imaging of a supraventricular volume of interest of 8 x 8 x 2 cm(3) (64 voxels). In DTI, a segmental spin-echo sequence (T(R)/T(E)=5500/91) was used and slices were stacked to reproduce the slab used in MRS. The spatial distributions of choline and N-acetylaspartate (NAA) correlated to mean fractional anisotropy and apparent diffusion coefficient (ADC) for the inner 6 x 6=36 voxels defined in MRS, most notably NAA and ADC value (r=-.70, P<.00001; correlation across four subjects, 144 data pairs). This is the first association of neuron metabolite contents in volunteers with structure as indicated by DTI. PMID:16275423

Irwan, Roy; Sijens, Paul E; Potze, Jan-Hendrik; Oudkerk, Matthijs

2005-09-19

21

Remote sensing of the proton aurora characteristics from IMAGE-FUV  

NASA Astrophysics Data System (ADS)

The combination of simultaneous global images of the north polar region obtained with the IMAGE-FUV imaging system makes it possible to globally map the properties of the electron and proton auroral precipitation. The SI12 imager, which observes the Doppler-shifted Lyman-a

Bisikalo, D. V.; Shematovich, V. I.; Gérard, J.-C.; Meurant, M.; Mende, S. B.; Frey, H. U.

2003-11-01

22

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

NASA Astrophysics Data System (ADS)

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.

2012-10-01

23

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

24

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

25

Proton spectroscopic imaging of the human prostate at 7 T.  

PubMed

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

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

2009-06-01

26

The electron and proton aurora as seen by IMAGE-FUV and FAST  

NASA Astrophysics Data System (ADS)

The Far Ultraviolet Instrument (FUV) on the IMAGE spacecraft observes the aurora in three different channels. One of them (SI12) is sensitive to the signal from precipitating protons, while the other two (WIC and SI13) observe auroral emissions which are not only excited by precipitating electrons, but also by protons. We examine a period when in-situ particle measurements by the FAST spacecraft were available simultaneously with global imaging with FUV. The measured electron and proton energy spectra are used to calculate the auroral brightness along the FAST orbit. The comparison with the FUV/IMAGE observations shows good quantitative agreement and demonstrates that under certain circumstances high proton fluxes may produce significant amounts of auroral FUV emission.

Frey, H. U.; Mende, S. B.; Carlson, C. W.; Gérard, J.-C.; Hubert, B.; Spann, J.; Gladstone, R.; Immel, T. J.

27

Proton and fluorine NMR imaging for the assessment of myocardial perfusion  

SciTech Connect

A high field, small bore NMR spectrometer was converted to an imaging system for the detection of fluorine and protons in phantoms and small biological samples. The modified spectrometer system was used to image various phantoms for the assessment of imaging performance. After assessment of the imaging system performance, a water soluble fluorinated compound of relatively low toxicity was investigated for use as an imaging agent for the detection of myocardial perfusion. New Zealand white rabbits were used as the model. Hearts were rapidly extracted and hung via the aorta to a perfusion apparatus which was capable of prolonging heart function throughout the course of the experiment. Perfusion with a standard nutrient solution was followed either by perfusion with a solution to which the fluorinated compound had been added or by ligation of the left coronary artery with subsequent perfusion with the fluorinated compound in perfusate solution. The hearts were then sectioned and imaged. The ligation of the left coronary artery produced a region of impaired perfusion in the left ventricular wall and parts of the septum. The regions of reduced perfusion appeared in the F-19 NMR images as areas of reduced intensity. Proton images of the tissue sections were also obtained for comparison. It was found that infarcted regions may be best visualized by combining the fluorine and proton images. Infarct damage was verified by Gentian violet stain. Relaxation times of fluorine and protons were measured both in perfused tissue and in various concentration solutions.

Horner, B.S.D.

1985-01-01

28

Optimization neural networks for the segmentation of magnetic resonance images  

Microsoft Academic Search

The application of the Hopfield neural network for the multispectral unsupervised classification of MR images is reported. Winner-take-all neurons were used to obtain a crisp classification map using proton density-weighted and T2-weighted images in the head. The preliminary studies indicate that the number of iterations needed to reach `good' solutions was nearly constant with the number of clusters chosen for

S. C. Amartur; D. Piraino; Y. Takefuji

1992-01-01

29

Electron and proton excitation of the FUV aurora: Simultaneous IMAGE and NOAA observations  

NASA Astrophysics Data System (ADS)

The Far Ultraviolet (FUV) imaging system on board the IMAGE satellite provides a global view of the north auroral region in different spectral channels. The Wideband Imaging Camera (WIC) is sensitive to the N2 LBH emission and NI emissions produced by both electron and proton precipitations. The SI12 camera images the Lyman-? emission due to incident protons only. We compare WIC and SI12 observations with model predictions based on particle measurements from the TED and the MEPED detectors on board NOAA-TIROS spacecraft. Models of the interaction of auroral particles with the atmosphere are used together with the in situ proton and electron flux and characteristic energy data to calculate the auroral brightness at the magnetic footprint of the NOAA-15 and NOAA-16 orbital tracks. The MEPED experiment measures the precipitating particles with energy higher than 30 keV, so that these comparisons include all auroral energies, in contrast to previous comparisons. A satisfactory agreement in morphology and in magnitude is obtained for most satellite overflights. The observed FUV-WIC signal is well modeled if the different spatial resolution of the two sensors is considered and the in situ measurements properly smoothed. The calculated count rate includes contributions from LBH emission, the NI 149.3 nm line, and the OI 135.6 nm line excited by electrons and protons. The proton contribution in WIC can locally dominate the electrons. The comparisons indicate that protons can significantly contribute to the FUV aurora at specific times and places and cannot be systematically neglected. The results confirm the shift of the proton auroral oval equatorward of the electron oval in the dusk sector. We also show that in some regions, especially in the dusk sector, high-energy protons dominate the proton energy flux and account for a large fraction of the Lyman-? and other FUV emissions.

Coumans, V.; GéRard, J.-C.; Hubert, B.; Evans, D. S.

2002-11-01

30

A scintillating plastic fiber tracking detector for neutron and proton imaging and spectroscopy  

NASA Astrophysics Data System (ADS)

We report on a prototype detector system designed to perform imaging and spectroscopy on 20-250MeV neutrons. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. The detector measures the energy and direction of neutrons by detecting double neutron-proton scatters and recording images of the ionization tracks of the recoil protons in a densely packed bundle of scintillating plastic fibers stacked in orthogonal layers. The scintillation tracks are detected and imaged by photomultipliers and image intensifier/CCD camera optics. By tracking the recoil protons from individual neutrons, the kinematics of the scatter are determined. This directional information results in a high signal-to-noise measurement. The self-triggering and track imaging features of a prototype for tracking in two dimensions are demonstrated in calibrations with 14-65MeV neutrons, 20-67.5MeV protons, and with cosmic-ray muons. Preliminary results of phantom imaging measurements using a proton beam are also presented. We discuss several applications for this detector technique and outline future development work.

Ryan, J. M.; Castaneda, C. M.; Holslin, D.; Macri, J. R.; McConnell, M. L.; Romero, J. L.; Wunderer, C. B.

1999-02-01

31

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

Microsoft Academic Search

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

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

1996-01-01

32

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

NASA Astrophysics Data System (ADS)

An indirect proton flux measuring tool based on discrimination of the energy deposited by protons in 128×128 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° 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.

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

2006-05-01

33

Methadone-induced toxic leukoencephalopathy: MR imaging and MR proton spectroscopy findings.  

PubMed

We report the clinical, MR imaging, and proton MR spectroscopy findings in a middle-aged woman with proved methadone-induced toxic leukoencephalopathy. The imaging characteristics of this unusual condition have been reported only rarely in the medical literature. We show that the imaging findings in methadone-induced toxic leukoencephalopathy are similar, though not identical, to previously reported cases of neurologic deterioration due to heroin inhalation. PMID:19892815

Salgado, R A; Jorens, P G; Baar, I; Cras, P; Hans, G; Parizel, P M

2009-11-05

34

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

PubMed Central

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

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

2009-01-01

35

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

SciTech Connect

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

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

2012-02-15

36

Sensitivity and Source of Amine-Proton Exchange and Amide-Proton Transfer Magnetic Resonance Imaging in Cerebral Ischemia.  

PubMed

PURPOSE: Amide-proton transfer (APT) and amine-water proton exchange (APEX) MRI can be viable to map pH-decreasing ischemic regions. However, their exact contributions are unclear. METHODS: We measured APEX- and APT-weighted magnetization transfer ratio asymmetry (denoted as APEXw and APTw), apparent diffusion coefficient, T(2) , and T(1) images and localized proton spectra in rats with permanent middle cerebral artery occlusion at 9.4 T. Phantoms and theoretical studies were also performed. RESULTS: Within 1-h postocclusion, APEXw and APTw maps showed hyperintensity (3.1% of M(0) ) and hypointensity (-1.8%), respectively, in regions with decreased apparent diffusion coefficient. Ischemia increased lactate and gamma aminobutyric acid concentrations, but decreased glutamate and taurine concentrations. Over time, the APEXw contrast decreased with glutamate, taurine, and creatine, whereas the APTw contrast and lactate level were similar. Phantom and theoretical studies suggest that the source of APEXw signal is mainly from proteins at normal pH, whereas at decreased pH, gamma aminobutyric acid and glutamate contributions increase, inducing the positive APEXw contrast in ischemic regions. The APTw contrast is sensitive to lactate concentration and pH, but contaminated from contributions of the faster APEX processes. CONCLUSION: Positive APEXw contrast is more sensitive to ischemia than negative APTw contrast. They may provide complementary tissue metabolic information. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc. PMID:23401310

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

2013-02-11

37

Proton and Fluorine NMR Imaging for the Assessment of Myocardial Perfusion.  

NASA Astrophysics Data System (ADS)

A high field, small bore NMR spectrometer was converted to an imaging system for the detection of fluorine and protons in phantoms and small biological samples. Necessary equipment additions included a set of gradient field coils, gradient coil drivers and image reconstruction software. The modified spectrometer system was used to image various phantoms for the assessment of imaging performance. After assessment of the imaging system performance, a water soluble fluorinated compound of relatively low toxicity was investigated for use as an imaging agent for the detection of myocardial perfusion. New Zealand white rabbits were used as the model. Hearts were rapidly extracted and hung via the aorta to a perfusion apparatus which was capable of prolonging heart function throughout the course of the experiment. Perfusion with a standard nutrient solution was followed either by perfusion with a solution to which the fluorinated compound had been added or by ligation of the left coronary artery with subsequent perfusion with the fluorinated compound in perfusate solution. The hearts were then sectioned and imaged. The ligation of the left coronary artery produced a region of impaired perfusion in the left ventricular wall and parts of the septum. The regions of reduced perfusion appeared in the F-19 NMR images as areas of reduced intensity. Proton images of the tissue sections were also obtained for comparison. It was found that infarcted regions may be best visualized by combining the fluorine and proton images. Infarct damage was verified by Gentian violet stain. Relaxation times of fluorine and protons were measured both in perfused tissue and in various concentration solutions. Two methods of determining the amount of fluorine deposited in the myocardial tissue were also implemented; one method depended on NMR measurement and the other involved chemical analysis of the tissue.

Horner, Binda Sherye Dowdey

38

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.

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

2012-01-01

39

Seasonal effects on the proton auroral precipitation observed by IMAGE-FUV  

NASA Astrophysics Data System (ADS)

The statistical approach of the auroral electron precipitation has shown a summer/winter dissymmetry. Electron energy flux in the 1900-0300 MLT sector increases from summer to winter. The frequency of occurrence of intense aurora (with electron energy flux above 5 erg cm-2 s-1) in the dusk-to-midnight sector was observed to be 3 times higher under winter conditions (or conditions of local darkness) than under summer conditions (or in sunlight). On board the IMAGE satellite the FUV instruments monitor the aurora in three different spectral regions and especially one of them only images the auroral proton precipitation. The Wideband Imaging Camera (WIC) observes the molecular N_2 LBH and the atomic NI emissions between 140 and 180 nm. The two channels of the Spectrographic Imager (SI) respond to the Doppler shifted Lyman-? emission at 121.8 nm due to precipitating protons (SI12) and the electron auroral emission of OI at 135.6 nm (SI13). The auroral proton and electron energy fluxes are calculated from the IMAGE-FUV data, relying on energy degradation and auroral emission models. We will discuss possible seasonal asymmetry in the auroral proton precipitation. A statistical study is made with FUV data from 2 successive solstices to minimize effects due to the solar activity variations.

Coumans, V.; Gérard, J.-C.; Hubert, B.; Meurant, M.; Mende, S. B.

2003-04-01

40

MR Imaging and Proton MR Spectroscopy in Adult Krabbe Disease  

Microsoft Academic Search

Summary: We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical pre- sentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2- weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother.

Laura Farina; Alberto Bizzi; Gaetano Finocchiaro; Davide Pareyson; Angelo Sghirlanzoni; Barbara Bertagnolio; SakkuBai Naidu; Bhim S. Singhal; David A. Wenger

2000-01-01

41

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

42

Monte Carlo evaluation of the Filtered Back Projection method for image reconstruction in proton computed tomography  

NASA Astrophysics Data System (ADS)

In this paper the use of the Filtered Back Projection (FBP) Algorithm, in order to reconstruct tomographic images using the high energy (200-250 MeV) proton beams, is investigated. The algorithm has been studied in detail with a Monte Carlo approach and image quality has been analysed and compared with the total absorbed dose. A proton Computed Tomography (pCT) apparatus, developed by our group, has been fully simulated to exploit the power of the Geant4 Monte Carlo toolkit. From the simulation of the apparatus, a set of tomographic images of a test phantom has been reconstructed using the FBP at different absorbed dose values. The images have been evaluated in terms of homogeneity, noise, contrast, spatial and density resolution.

Cirrone, G. A. P.; Bucciolini, M.; Bruzzi, M.; Candiano, G.; Civinini, C.; Cuttone, G.; Guarino, P.; Lo Presti, D.; Mazzaglia, S. E.; Pallotta, S.; Randazzo, N.; Sipala, V.; Stancampiano, C.; Talamonti, C.

2011-12-01

43

Ionospheric Conductances Due To Auroral Proton and Electron Precipitation Deduced From Image-fuv Observations.  

NASA Astrophysics Data System (ADS)

The FUV instrument on the IMAGE (Imager for Magnetopause-to-Aurora Global Ex- ploration) satellite monitors the aurora in three different spectral regions. The Wide- band Imaging Camera (WIC) observes the molecular N2 LBH and the atomic NI emissions at 140-180 nm. The two channels of the Spectrographic Imager (SI) ob- serve the Doppler shifted Lyman- emission at 121.8 nm due to precipitating protons (SI12) and the electron auroral emission of OI at 135.6 nm (SI13). We calculate the Pedersen and Hall ionospheric conductances due to auroral particles based on FUV observations separately for the proton and electron precipitation. We first estimate the electron and proton energy fluxes from the FUV data, relying on energy degradation and auroral emission models. A two-stream model is used for the electron aurora while the proton aurora modeling is based on the direct Monte Carlo method, which gives a stochastic solution to the Boltzmann equations for the H+ - H beam. The electron energy is evaluated by combining observations from the three FUV instruments. For the proton energy, we use a statistical model based on in-situ particle measurements. Second, the particle energy and energy flux are used to estimate the ionization rates separately for protons and electrons, consistently with the energy degradation models. Finally, the electron and ion densities are estimated from ionization profiles, and the Pedersen and Hall conductances are calculated from fundamental equations. Appli- cations of the method to the distribution of the conductance at winter solstice in the course of substorm development over the north polar region will be illustrated.

Coumans, V.; Hubert, B.; Meurant, M.; Gérard, J.-C.; Shematovich, V. I.; Bisikalo, D. V.

44

Serial Proton MR Spectroscopic Imaging of Recurrent Malignant Gliomas after Gamma Knife Radiosurgery  

Microsoft Academic Search

BACKGROUND AND PURPOSE: The diagnosis of brain tumors after high-dose radiation therapy is frequently limited by the lack of metabolic discrimination available with conven- tional imaging methods. The purpose of this study was to use proton MR spectroscopy to investigate serial changes in recurrent malignant gliomas after gamma knife radiosurgery to characterize tissue response to high-dose radiation. METHODS: Eighteen patients

Edward E. Graves; Sarah J. Nelson; Daniel B. Vigneron; Lynn Verhey; Michael McDermott; David Larson; Susan Chang; Michael D. Prados; William P. Dillon

45

Analysis of Proton Radiography Images of Shock Melted\\/Damaged Tin  

Microsoft Academic Search

Tin coupons were shock damaged\\/melted under identical conditions with a diverging high explosive shock wave. Proton Radiography images and velocimetry data from experiments with seven different tin coupons of varying thickness are analyzed. Comparing experiments with identical samples allowed us to distinguish between repeatable and random features. Shapes and velocities of the main fragments are deterministic functions of the coupon

Hanna Makaruk; Nikita A. Sakhanenko; David B. Holtkamp; Tiffany Hayes; Joysree Aubrey

2007-01-01

46

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

NASA Astrophysics Data System (ADS)

Simultaneous measurements of auroral limb H Lyman ?, H Balmer ?, H Balmer ?, N2+ 1 NG 391.4-nm, and N2 2 PG 337.1-nm emissions excited by combined proton/hydrogen/electron precipitation are reported. The data were recorded by the Ultraviolet and Visible Imaging and Spectrographic Imaging (UVISI) spectrographic imagers on the Midcourse Space Experiment (MSX) satellite on November 10, 1996, while viewing a diffuse emission region during a limb-scanning data collection event. Energy fluxes associated with the electron and proton/hydrogen precipitation components are estimated with one-dimensional fits to selected limb profiles using a transport-theoretic model. Spectral radiances (110-900 nm) are also presented. The data presented here are but one example of the large number of MSX/UVISI data sets that have been collected offering opportunities for scientific investigations of auroral emission phenomena and for retrieval of composition and particle precipitation parameters from optical remote sensing data.

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

2001-01-01

47

NOTE: The influence of CT image noise on proton range calculation in radiotherapy planning  

NASA Astrophysics Data System (ADS)

The purpose of this note is to evaluate the relationship between the stochastic errors in CT numbers and the standard deviation of the computed proton beam range in radiotherapy planning. The stochastic voxel-to-voxel variation in CT numbers called 'noise,' may be due to signal registration, processing and numerical image reconstruction technique. Noise in CT images may cause a deviation in the computed proton range from the physical proton range, even assuming that the error due to CT number-stopping power calibration is removed. To obtain the probability density function (PDF) of the computed proton range, we have used the continuing slowing down approximation (CSDA) and the uncorrelated white Gaussian noise along the proton path. The model of white noise was accepted because for the slice-based fan-beam CT scanner; the power-spectrum properties apply only to the axial (x, y) domain and the noise is uncorrelated in the z domain. However, the possible influence of the noise power spectrum on the standard deviation of the range should be investigated in the future. A random number generator was utilized for noise simulation and this procedure was iteratively repeated to obtain convergence of range PDF, which approached a Gaussian distribution. We showed that the standard deviation of the range, ?, increases linearly with the initial proton energy, computational grid size and standard deviation of the voxel values. The 95% confidence interval width of the range PDF, which is defined as 4?, may reach 0.6 cm for the initial proton energy of 200 MeV, computational grid 0.25 cm and 5% standard deviation of CT voxel values. Our results show that the range uncertainty due to random errors in CT numbers may be significant and comparable to the uncertainties due to calibration of CT numbers. Presented at the 51st Annual Meeting of the American Association of Physicists in Medicine, Anaheim, CA, July 26-30, 2009.

Chvetsov, Alexei V.; Paige, Sandra L.

2010-03-01

48

The influence of CT image noise on proton range calculation in radiotherapy planning.  

PubMed

The purpose of this note is to evaluate the relationship between the stochastic errors in CT numbers and the standard deviation of the computed proton beam range in radiotherapy planning. The stochastic voxel-to-voxel variation in CT numbers called 'noise,' may be due to signal registration, processing and numerical image reconstruction technique. Noise in CT images may cause a deviation in the computed proton range from the physical proton range, even assuming that the error due to CT number-stopping power calibration is removed. To obtain the probability density function (PDF) of the computed proton range, we have used the continuing slowing down approximation (CSDA) and the uncorrelated white Gaussian noise along the proton path. The model of white noise was accepted because for the slice-based fan-beam CT scanner; the power-spectrum properties apply only to the axial (x, y) domain and the noise is uncorrelated in the z domain. However, the possible influence of the noise power spectrum on the standard deviation of the range should be investigated in the future. A random number generator was utilized for noise simulation and this procedure was iteratively repeated to obtain convergence of range PDF, which approached a Gaussian distribution. We showed that the standard deviation of the range, sigma, increases linearly with the initial proton energy, computational grid size and standard deviation of the voxel values. The 95% confidence interval width of the range PDF, which is defined as 4sigma, may reach 0.6 cm for the initial proton energy of 200 MeV, computational grid 0.25 cm and 5% standard deviation of CT voxel values. Our results show that the range uncertainty due to random errors in CT numbers may be significant and comparable to the uncertainties due to calibration of CT numbers. PMID:20182006

Chvetsov, Alexei V; Paige, Sandra L

2010-02-24

49

Clinical perspectives of hybrid proton-fluorine magnetic resonance imaging and spectroscopy.  

PubMed

The number of applications of fluorine 19 (19F) magnetic resonance (MR) imaging and spectroscopy in biomedical and clinical research is steadily growing. The 100% natural abundance of fluorine and its relatively high sensitivity for MR (83% to that of protons) make it an interesting nucleus for a wide range of MR applications. Fluorinated contrast media have a number of advantages over the conventionally used gadolinium-based or iron-based contrast agents. The absence of an endogenous fluorine background intensity in the human body facilitates reliable quantification of fluorinated contrast medium or drugs. Anatomy can be visualized separately with proton MR imaging, creating the application of hybrid hydrogen 1 (1H)/19F MR imaging. The availability of 2 channels (ie, the 1H and 19F channels) enables dual-targeted molecular imaging. Recently, novel developments have emerged on fluorine-based contrast media in preclinical studies and imaging techniques. The developments in fluorine MR seem promising for clinical applications, with contributions in therapy monitoring, assessment of lung function, angiography, and molecular imaging. This review outlines the translation from recent advances in preclinical MR imaging and spectroscopy to future perspectives of clinical hybrid 1H/19/F MR imaging applications. PMID:23211551

Wolters, Martijn; Mohades, Seyede G; Hackeng, Tilman M; Post, Mark J; Kooi, Marianne E; Backes, Walter H

2013-05-01

50

Realistic transverse images of the proton charge and magnetization densities  

SciTech Connect

We develop a technique, denoted as the finite radius approximation (FRA), that uses a two-dimensional version of the Nyquist-Shannon sampling theorem to determine transverse densities and their uncertainties from experimental quantities. Uncertainties arising from experimental uncertainties on the form factors and lack of measured data at high Q{sup 2} are treated. A key feature of the FRA is that a form factor measured at a given value of Q{sup 2} is related to a definite region in coordinate space. An exact relation between the FRA and the use of a Bessel series is derived. The proton Dirac form factor is sufficiently well known such that the transverse charge density is very accurately known except for transverse separations b less than about 0.1 fm. The Pauli form factor is well known to Q{sup 2} of about 10 GeV{sup 2}, and this allows a reasonable, but improvable, determination of the anomalous magnetic moment density.

Venkat, Siddharth [Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0002 (United States); Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Arrington, John; Zhan Xiaohui [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Miller, Gerald A. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2011-01-15

51

Analysis of the performance of CMOS APS imagers after proton damage  

NASA Astrophysics Data System (ADS)

In this work we have irradiated a standard commercial CMOS imager with a 24 MeV proton beam at INFN Laboratori Nazionali del Sud, Catania (Italy) up to a nominal fluence of 1014 [protons/cm-2]. The device under test was a standard VGA detector, fabricated with a 130 nm technology without radiation hardening. During the irradiation the detector was operated to monitor the progressive damaging of the sensor and the associated on-pixel electronics. After 18 months from the irradiation damage session, with the detector stored at room temperature, a study on the detection efficiency and charge collection capability has been carried out using fluorescent X-ray photons, emitted from copper target. We found that the detector is still working at 1013 protons/cm2, with a moderate increase of the noise and a slightly decrease of the detection capabilities.

Meroli, S.; Passeri, D.; Servoli, L.; Angelucci, A.

2013-02-01

52

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

53

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

NASA Astrophysics Data System (ADS)

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

Zheng, Jie

54

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

55

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

NASA Astrophysics Data System (ADS)

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 describe the algorithms used for simulations through typical 2D and 3D meshes. We 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.

Schach von Wittenau, Alexis E.; Aufderheide, Maurice; Henderson, Gary

2011-10-01

56

Cesium Iodide Crystal Calorimeter of the Proton Computed Tomography (pCT) Imager  

NASA Astrophysics Data System (ADS)

Researchers at SCIPP, LLMU and NIU have collaborated to make a functioning proton imager. Proton Computed Tomography (pCT) is designated to be applied in proton therapy of human cancer systems. It will image head-sized phantom objects and provide excellent space and energy resolution using a silicon microstrip tracker and crystal calorimetry. The residual energy could be measured with precision of a few percent using a Cesium Iodide crystal calorimeter. A single element of the CsI(TI) calorimeter was tested in order to understand the behavior of the future calorimeter system. We present test results on a CsI(TI) calorimeter element with proton beams of 35, 100 and 200MeV. The detector element was designed to comply with the demands of high energy resolution of a few percent and a dynamic range of two orders of magnitude (1-300MeV) under a counting rate of 10 kHz per channel. We also report on cosmic measurement results of each crystal of the future calorimeter matrix. A detailed description of the calorimeter data acquisition system will be given.

Missaghian, Jessica; Sadrozinski, Hartmut; Colby, Brian; Rykalin, Victor; Hurley, Ford

2009-11-01

57

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

NASA Astrophysics Data System (ADS)

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

Žitnik, M.; Pelicon, P.; Grlj, N.; Karydas, A. G.; Sokaras, D.; Schütz, R.; Kanngießer, B.

2008-09-01

58

Fixed fluorescent images of an 80 MeV proton pencil beam  

NASA Astrophysics Data System (ADS)

We have used an organic radio-fluorogenic gel to make fixed fluorescent images of the track of an 80 MeV proton pencil beam NB this is not a scintillation effect; rather a small fraction of the molecules of the medium are converted permanently from a non-emissive to an emissive form. The spatial resolution of the images is better than 0.1 mm and the cuboid form of the gels allows the track to be viewed along the direction of the beam or transverse to it. The fluorescence diverges and increases in intensity with increasing depth up to the Bragg peak with 80-20% post-peak fall-off in 1.4±0.1 mm. From the effect of interposed polystyrene sheets on the proton range in the gel, its water equivalent thickness is determined to be 0.91.

Warman, J. M.; de Haas, M. P.; Luthjens, L. H.; Denkova, A. G.; Kavatsyuk, O.; van Goethem, M.-J.; Kiewiet, H. H.; Brandenburg, S.

2013-04-01

59

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

Microsoft Academic Search

A small degree of nonuniformity in dialysate flow in a hollow-fiber dialyzer was detected using proton magnetic resonance imaging (MRI). Since paramagnetic ions reduce the spin-lattice relaxation time of protons around them, MRI can detect Gd in water. An aqueous solution of a chelate compound of Gd was impulsively injected into the dialysate flow path at a flow rate of

T. Osuga; T. Obata; H. Ikehira

2004-01-01

60

Localised proton spectroscopy and spectroscopic imaging in cerebral gliomas, with comparison to positron emission tomography  

Microsoft Academic Search

In 32 patients with gliomas, one- and two-dimensional proton magnetic resonance spectroscopy ( 1H-MRS) has been conducted, the latter allowing reconstruction of spectroscopic data into a spectroscopic image (MRSI), showing the distribution of the various metabolite concentrations over the cross-sectional plane. For lack of absolute concentrations, the measured concentrations of phosphocholine (CHOL), N -acetyl-L-aspartate (NAA), and lactate (LAC) were conventionally

K. G. Go; R. L. Kamman; E. L. Mooyaart; M. A. A. M. Heesters; J. Pruim; W. Vaalburg; A. M. J. Paans

1995-01-01

61

Methodology for the measurement and analysis of relaxation times in proton imaging  

Microsoft Academic Search

Measurements of proton T1 and T2 were performed on GdClâ solutions (20 less than T2 less than 500 msec, 90 less than T1 less than 1000 msec) on large-bore NMR imaging systems operating at 1.0T and 1.5T. CPMG multi-echo (ME), multiple saturation recovery (MSR) and modified fast inversion recovery (MFIR) pulse sequences as well as a sequence that combines and

James R. MacFall; Felix W. Wehrli; Robert K. Breger; G. Allan Johnson

1987-01-01

62

Regionally Specific Neuronal Pathology in Untreated Patients with Schizophrenia: A Proton Magnetic Resonance Spectroscopic Imaging Study  

Microsoft Academic Search

Background: Proton magnetic resonance spectroscopic imaging (1H-MRSI) studies have reported reductions of N-acetyl aspartate (NAA), a marker of neuronal integrity, in the hippocampal region (HIPPO) and dorsolateral prefrontal cortex (DLPFC) of pharmacologically treated patients with schizophrenia. The purpose of the present study was twofold: to exclude drug treatment as a source of the previous findings and to examine NAA relative

Alessandro Bertolino; Joseph H. Callicott; Igor Elman; Venkata S. Mattay; Gioacchino Tedeschi; Joseph A. Frank; Alan Breier; Daniel R. Weinberger

1998-01-01

63

Cosmic ray proton spectrum determined with the imaging atmospheric Cherenkov technique  

Microsoft Academic Search

The HEGRA system of 4 imaging atmospheric Cherenkov telescopes (IACTs) has been used to determine the flux and the spectrum of cosmic ray protons over a limited energy range around 1.5 TeV. Although the IACT system is designed for the detection of gamma-rays with energies above 500 GeV, it has also a large detection area of ~=106 m2×3 msr for

F. Aharonian; A. G. Akhperjanian; J. A. Barrio; A. S. Belgarian; K. Bernlöhr; J. J. G. Beteta; H. Bojahr; S. Bradbury; I. Calle; J. L. Contreras; J. Cortina; A. Daum; T. Deckers; S. Denninghoff; V. Fonseca; J. C. Gonzalez; G. Heinzelmann; M. Hemberger; G. Hermann; M. Hess; A. Heusler; W. Hofmann; H. Hohl; I. Holl; D. Horns; A. Ibarra; R. Kankanyan; M. Kestel; O. Kirstein; C. Köhler; A. Konopelko; H. Kornmeyer; D. Kranich; H. Krawczynski; H. Lampeitl; A. Lindner; E. Lorenz; N. Magnussen; H. Meyer; R. Mirzoyan; A. Moralejo; L. Padilla; M. Panter; D. Petry; R. Plaga; A. Plyasheshnikov; J. Prahl; C. Prosch; G. Pühlhofer; G. Rauterberg; C. Renault; W. Rhode; A. Röhring; V. Sahakian; M. Samorski; D. Schmele; F. Schröder; W. Stamm; H. J. Völk; B. Wiebel-Sooth; C. A. Wiedner; M. Willmer; H. Wirth

1999-01-01

64

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

Microsoft Academic Search

Large lipid signals and strong susceptibility gradients introduced by muscle–bone interfaces represent major technical challenges forin 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 2D1H CSI technique

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

1997-01-01

65

Detection of necrosis in human tumour xenografts by proton magnetic resonance imaging.  

PubMed Central

Tumours with necrotic regions have an inadequate blood supply and are expected to differ from well-vascularised tumours in response to treatment. The purpose of the present work was to investigate whether proton magnetic resonance imaging (MRI) might be used to detect necrotic regions in tumours. MR images and histological sections from individual tumours of three different amelanotic human melanoma xenograft lines (BEX-t, HUX-t, SAX-t) were analysed in pairs. MRI was performed at 1.5 T using two spin-echo pulse sequences, one with a repetition time (TR) of 600 ms and echo times (TEs) of 20, 40, 60 and 80 ms and the other with a TR of 2000 ms and TEs of 20, 40, 60 and 80 ms. Spin-lattice relaxation time (T1), spin-spin relaxation time (T2) and proton density (N0) were calculated for each volume element corresponding to a pixel. Synthetic MR images, pure T1, T2 and N0 images and spin-echo images with chosen values for TR and TE were generated from these data. T1, T2 and N0 distributions of tumour subregions, corresponding to necrotic regions and regions of viable tissue as defined by histological criteria, were also generated. T1 and T2 were significantly shorter in the necrotic regions than in the regions of viable tissue in all tumours. These differences were sufficiently large to allow the generation of synthetic spin-echo images showing clear contrast between necrosis and viable tissue. Maximum contrast was achieved with TRs within the range 2800-4000 ms and TEs within the range 160-200 ms. Necrotic tissue could also be distinguished from viable tissue in pure T1 and T2 images. Consequently, the possibility exists that MRI might be used for detection of necrotic regions in tumours and hence for prediction of tumour treatment response. Images Figure 4 Figure 5

Jakobsen, I.; Kaalhus, O.; Lyng, H.; Rofstad, E. K.

1995-01-01

66

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

67

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

68

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

69

Identification of cholesteryl esters in human carotid atherosclerosis by ex vivo image-guided proton MRS.  

PubMed

Vulnerable atherosclerotic plaques may be identified by their large lipid component, particularly liquid cholesteryl ester (CE), covered by a fibrous cap. We hypothesized that image-guided 1H proton magnetic resonance spectroscopy (MRS) would identify mobile CE in discrete, preselected regions of atherosclerotic plaque. Human carotid endarterectomy specimens (n = 10) were imaged ex vivo by magnetic resonance imaging (MRI) at high field (11.7 T) utilizing standard T1- and T2-weighted spin echo protocols. MRS spectra were acquired from 1 mm3 voxels, localized to plaque regions that we judged by MRI to be lipid rich or lipid poor. The spectra revealed methyl and methylene resonances of fatty acyl chains with relative intensities and linewidths characteristic of pure CE, by comparison with lipid standards. Regions judged to be lipid rich by MRI showed much more intense CE resonances than did lipid-poor regions. The integrated intensities of lipid peaks were 5.5 +/- 2.0% (lipid-rich regions) versus 0.9 +/- 0.6% (lipid-poor regions) of the unsuppressed water peak (P < 0.0001). Lipid distribution by histology, MRS, and MRI showed strong correlation. Image-guided proton MRS accurately identified CE in selected regions of atherosclerotic plaque as small as 1 mm3 in an ex vivo setting. This procedure may permit the noninvasive detection and quantification of CE in atherosclerotic plaque in vivo. PMID:16317172

Ruberg, Frederick L; Viereck, Jason; Phinikaridou, Alkystis; Qiao, Ye; Loscalzo, Joseph; Hamilton, James A

2005-11-29

70

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

71

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.

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

2013-01-01

72

Determination of electron and proton auroral energy inputs from FUV-IMAGE  

NASA Astrophysics Data System (ADS)

The FUV experiment onboard the IMAGE spacecraft offers the unique possibility to obtain simultaneous snapshots of the global north aurora every 2 minutes in three different spectral channels. The WIC camera has a broadband channel covering the 135-190 nm interval including the N2 LBH bands, part of which may be absorbed by O2. The SI13 channel is centered on the OI 135.6 nm line which is optically thin and includes a ~ 40% LBH contribution. Finally, the SI12 camera images the Doppler-shifted Ly-? emission excited by the proton aurora. This set of instrumentation is combined with auroral models to determine the electron and the proton energy fluxes from the magnetosphere. Examples will be presented and compared with the values deduced from the NOAA satellites. Simultaneous in-situ measurements of the particle characteristic energy have been combined with the data extracted from the FUV images to validate the models and derive empirical relationships between the particle flux measured by the detectors and the brightness observed by FUV-IMAGE at the footprint of the same magnetic field line. Finally, we will assess the ability to deduce the characteristic energy of the auroral particles from the ratio of co-registered images in the WIC and SI13 cameras. This method is based on the difference of vertical distribution of the LBH and the OI 135.6 nm emissions. It offers the potential to globally remotely sense not only the energy flux from the magnetosphere but also the main features of the electron characteristic energy.

Gérard, J.; Hubert, B.; Meurant, M.; Frey, H. U.; Mende, S. B.; Immel, T.; Bisikalo, D. V.; Shematovich, V. I.; Gladstone, G. R.

2001-05-01

73

Image Guidance Based on Prostate Position for Prostate Cancer Proton Therapy  

SciTech Connect

Purpose: To determine the target coverage for proton therapy with and without image guidance and daily prebeam reorientation. Methods and Materials: A total of 207 prostate positions were analyzed for 9 prostate cancer patients treated using our low-risk prostate proton therapy protocol (University of Florida Proton Therapy Institute 001). The planning target volume was defined as the prostate plus a 5-mm axial and 8-mm superoinferior extension. The prostate was repositioned using 5- and 10-mm shifts (anteriorly, inferiorly, posteriorly, and superiorly) and for Points A-D using a combination of 10-mm multidimensional movements (anteriorly or inferiorly; posteriorly or superiorly; and left or right). The beams were then realigned using the new prostate position. The prescription dose was 78 Gray equivalent (GE) to 95% of the planning target volume. Results: For small movements in the anterior, inferior, and posterior directions within the planning target volume ({<=}5 mm), treatment realignment demonstrated small, but significant, improvements in the clinical target volume (CTV) coverage to the prescribed dose (78 GE). The anterior and posterior shifts also significantly increased the minimal CTV dose ({delta} +1.59 GE). For prostate 10-mm movements in the inferior, posterior, and superior directions, the beam realignment produced larger and significant improvements for both the CTV V{sub 78} ({delta} +6.4%) and the CTV minimal dose ({delta} +8.22 GE). For the compounded 10-mm multidimensional shifts, realignment significantly improved the CTV V{sub 78} ({delta} +11.8%) and CTV minimal dose ({delta} +23.6 GE). After realignment, the CTV minimal dose was >76.6 GE (>98%) for all points (A-D). Conclusion: Proton beam realignment after target shift will enhance CTV coverage for different prostate positions.

Vargas, Carlos [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)], E-mail: c2002@ufl.edu; Wagner, Marcus [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Indelicato, Daniel [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Fryer, Amber; Horne, David; Chellini, Angela; McKenzie, Craig; Lawlor, Paula; Mahajan, Chaitali; Li Zuofeng; Lin Liyong; Keole, Sameer [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

2008-08-01

74

Prompt gamma imaging with a slit camera for real-time range control in proton therapy  

NASA Astrophysics Data System (ADS)

Treatments delivered by proton therapy are affected by uncertainties on the range of the beam within the patient, requiring medical physicists to add safety margins on the penetration depth of the beam. To reduce these margins and deliver safer treatments, different projects are currently investigating real-time range control by imaging prompt gammas emitted along the proton tracks in the patient. This study reports on the feasibility, development and test of a new concept of prompt gamma camera using a slit collimator to obtain a one-dimensional projection of the beam path on a scintillation detector. This concept was optimized, using the Monte Carlo code MCNPX version 2.5.0, to select high energy photons correlated with the beam range and detect them with both high statistics and sufficient spatial resolution. To validate the Monte Carlo model, spectrometry measurements of secondary particles emitted by a PMMA target during proton irradiation at 160 MeV were realized. An excellent agreement with the simulations was observed when using subtraction methods to isolate the gammas in direct incidence. A first prototype slit camera using the HiCam gamma detector was consequently prepared and tested successfully at 100 and 160 MeV beam energies. Results confirmed the potential of this concept for real-time range monitoring with millimetre accuracy in pencil beam scanning mode for typical clinical conditions. If we neglect electronic dead times and rejection of detected events, the current solution with its collimator at 15 cm from the beam axis can achieve a 1-2 mm standard deviation on range estimation in a homogeneous PMMA target for numbers of protons that correspond to doses in water at the Bragg peak as low as 15 cGy at 100 MeV and 25 cGy at 160 MeV assuming pencil beams with a Gaussian profile of 5 mm sigma at target entrance.

Smeets, J.; Roellinghoff, F.; Prieels, D.; Stichelbaut, F.; Benilov, A.; Busca, P.; Fiorini, C.; Peloso, R.; Basilavecchia, M.; Frizzi, T.; Dehaes, J. C.; Dubus, A.

2012-06-01

75

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

SciTech Connect

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

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

2008-01-01

76

Part 1: Dual-tuned proton/sodium magnetic resonance imaging of the lumbar spine in a rabbit model  

PubMed Central

Study Design Development of a dual-tuned proton/sodium RF coil for magnetic resonance (MR) imaging of the rabbit spine and quantification of sodium concentration in intervertebral discs. Objective To develop the dual-tuned proton/sodium MR imaging of rabbit lumbar spine to investigate proteoglycan matrix content and intervertebral disc degeneration (IDD). Summary of Background Data IDD is a common chronic condition that may lead to back pain, limited activity, and disability. Early stage IDD involves the loss of proteoglycan matrix and water content in the disc. Sodium MR imaging is a promising noninvasive technique for quantitative measurement of proteoglycan changes associated with IDD. The combined structural (proton) and biochemical (sodium) MR imaging facilitates the investigation of morphological and molecular changes associated with degeneration of discs. Methods Multi-channel dual-tuned proton/sodium transceiver RF coil of the rabbit spine was developed and optimized at 3T human scanner – eight channels allocated for the sodium coil and four channels for the proton coil. High-resolution anatomy proton images of the discs were acquired using turbo spin echo and dual echo steady state sequence. Sodium concentration of the discs was quantified from sodium MR images that were calibrated for signal attenuation due to RF field inhomogeneity, sodium MR relaxation times, and disc thickness. Twelve rabbits (~1 year old, female, 5.2 ± 0.4 kg) were used for measuring disc sodium concentration. Results High-resolution in vivo proton and sodium MR images of rabbit discs (? 2-mm thickness) were successfully obtained using an in-house dual-tuned proton/sodium RF coil at 3T. The total acquisition time for each set of images was approximately 40 minutes. Sodium concentration of normal rabbit lumbar discs was measured 269.7 ± 6.3 mM, and this measurement was highly reproducible, with 5.3% of coefficient of variation. Conclusion Sodium concentrations of rabbit lumbar discs were reliably measured using our newly developed dual-tuned multi-channel proton/sodium RF coil at 3T.

Moon, Chan Hong; Kim, Jung-Hwan; Jacobs, Lloydine; Zhao, Tiejun; Sowa, Gwendolyn; Vo, Nam; Kang, James; Bae, Kyongtae Ty

2012-01-01

77

Multichannel transceiver dual-tuned RF coil for proton/sodium MR imaging of knee cartilage at 3 T.  

PubMed

Sodium magnetic resonance (MR) imaging is a promising technique for detecting changes of proteoglycan (PG) content in cartilage associated with knee osteoarthritis. Despite its potential clinical benefit, sodium MR imaging in vivo is challenging because of intrinsically low sodium concentration and low MR signal sensitivity. Some of the challenges in sodium MR imaging may be eliminated by the use of a high-sensitivity radiofrequency (RF) coil, specifically, a dual-tuned (DT) proton/sodium RF coil which facilitates the co-registration of sodium and proton MR images and the evaluation of both physiochemical and structural properties of knee cartilage. Nevertheless, implementation of a DT proton/sodium RF coil is technically difficult because of the coupling effect between the coil elements (particularly at high field) and the required compact design with improved coil sensitivity. In this study, we applied a multitransceiver RF coil design to develop a DT proton/sodium coil for knee cartilage imaging at 3 T. With the new design, the size of the coil was minimized, and a high signal-to-noise ratio (SNR) was achieved. DT coil exhibited high levels of reflection S11 (?-21 dB) and transmission coefficient S12 (?-19 dB) for both the proton and sodium coils. High SNR (range 27-38) and contrast-to-noise ratio (CNR) (range 15-21) were achieved in sodium MR imaging of knee cartilage in vivo at 3-mm(3) isotropic resolution. This DT coil performance was comparable to that measured using a sodium-only birdcage coil (SNR of 28 and CNR of 20). Clinical evaluation of the DT coil on four normal subjects demonstrated a consistent acquisition of high-resolution proton images and measurement of relative sodium concentrations of knee cartilages without repositioning of the subjects during the same MR scanning session. PMID:22297242

Kim, Jung-Hwan; Moon, Chan Hong; Park, Bum-Woo; Furlan, Alessandro; Zhao, Tiejun; Bae, Kyongtae T

2012-01-30

78

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.

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

2013-01-01

79

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

NASA Astrophysics Data System (ADS)

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

Depauw, Nicolas; Seco, Joao

2011-04-01

80

Proton imaging of siloxanes to map tissue oxygenation levels (PISTOL): a tool for quantitative tissue oximetry†  

PubMed Central

Hexamethyldisiloxane (HMDSO) has been identified as a sensitive proton NMR indicator of tissue oxygenation (pO2) based on spectroscopic spin-lattice relaxometry. A rapid MRI approach has now been designed, implemented, and tested. The technique, proton imaging of siloxanes to map tissue oxygenation levels (PISTOL), utilizes frequency-selective excitation of the HMDSO resonance and chemical-shift selective suppression of residual water signal to effectively eliminate water and fat signals and pulse-burst saturation recovery 1H echo planar imaging to map T1 of HMDSO and hence pO2. PISTOL was used here to obtain maps of pO2 in rat thigh muscle and Dunning prostate R3327 MAT-Lu tumor-implanted rats. Measurements were repeated to assess baseline stability and response to breathing of hyperoxic gas. Each pO2 map was obtained in 3½ min, facilitating dynamic measurements of response to oxygen intervention. Altering the inhaled gas to oxygen produced a significant increase in mean pO2 from 55 Torr to 238 Torr in thigh muscle and a smaller, but significant, increase in mean pO2 from 17 Torr to 78 Torr in MAT-Lu tumors. Thus, PISTOL enabled mapping of tissue pO2 at multiple locations and dynamic changes in pO2 in response to intervention. This new method offers a potentially valuable new tool to image pO2 in vivo for any healthy or diseased state by 1H MRI.

Kodibagkar, Vikram D.; Wang, Xianghui; Pacheco-Torres, Jesus; Gulaka, Praveen; Mason, Ralph P.

2011-01-01

81

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

82

CBCT/CBDT equipped with the x-ray projection system for image-guided proton therapy  

NASA Astrophysics Data System (ADS)

For image-guided proton therapy, we investigated the feasibility of CBCT (cone-beam computed tomography) and CBDT (cone-beam digital tomosynthesis) technologies in the gantry treatment room. A fully equipped x-ray projection system, which was originally operated for patient alignment, in parallel to proton-beam direction was utilized for acquiring CBCT/CBDT. The performance of the imaging detector was analyzed in terms of MTF (modulation-transfer function), NPS (noise-power spectrum) and DQE (detective quantum efficiency). Tomographic imaging performances, such as spatial resolving power, linearity of CT numbers, SNR (signal-to-noise ratio), and CNR (contrast-to-noise ratio), were analyzed by using the AAPM (American Association of Physicists in Medicine) CT QC phantom. Geometric alignment of CBCT/CBDT system was analyzed by using a calibration phantom, which consists of steal ball bearings. The determined calibration parameters were applied to the image reconstruction procedures. The overall CBCT performances of the system were demonstrated with reconstructed humanoid phantom images. In addition, we implemented the CBDT with a selected number of projection views acquired for CBCT in limited angle ranges. From the reconstructed phantom images, the CBCT system in the gantry treatment room will be very useful as a primary patient alignment system for image-guided proton therapy. The CBDT may provide fast patient positioning with less motion artifact and patient doses.

Cho, Min Kook; Kim, Jin Sung; Cho, Young-Bin; Youn, Hanbean; Park, Sung Yong; Cho, Seungryong; Kim, Ho Kyung

2009-02-01

83

Non-invasive measurement and imaging of tissue iron oxide nanoparticle concentrations in vivo using proton relaxometry  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles and microparticles can be found in biological tissues for a variety of reasons including pathological deposition of biogenic particles, administration of synthetic particles for scientific or clinical reasons, and the inclusion of biogenic magnetic particles for the sensing of the geomagnetic field. In applied magnetic fields, the magnetisation of tissue protons can be manipulated with radiofrequency radiation such that the macroscopic magnetisation of the protons precesses freely in the plane perpendicular to the applied static field. The presence of magnetic particles within tissue enhances the rate of dephasing of proton precession with higher concentrations of particles resulting in higher dephasing rates. Magnetic resonance imaging instruments can be used to measure and image the rate of decay of spin echo recoverable proton transverse magnetisation (R2) within tissues enabling the measurement and imaging of magnetic particle concentrations with the aid of suitable calibration curves. Applications include the non-invasive measurement of liver iron concentrations in iron-overload disorders and measurement and imaging of magnetic particle concentrations used in magnetic hyperthermia therapy. Future applications may include the tracking of magnetically labelled drugs or biomolecules and the measurement of fibrotic liver damage.

St. Pierre, T. G.; Clark, P. R.; Chua-anusorn, W.; Fleming, A.; Pardoe, H.; Jeffrey, G. P.; Olynyk, J. K.; Pootrakul, P.; Jones, S.; Moroz, P.

2005-01-01

84

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

Microsoft Academic Search

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

M. Moteabbed; S. España; H. Paganetti

2011-01-01

85

PIXE profiling, imaging and analysis using the NAC proton microprobe: Unraveling mantle eclogites  

NASA Astrophysics Data System (ADS)

The National Accelerator Centre (NAC) proton microprobe has been carefully calibrated by the analysis of pure element, primary steel and geological standards. The results obtained are generally accurate to within 5%. For routine analyses (6-8 min), detection limits in the X-ray energy region 7-20 keV, range from 1.5 to 5 ppm. Previous workers have suggested the use of a (H2)+ beam for semi-quantitative analysis and imaging as higher beam brightness is obtainable with this beam at NAC. However, insufficient suppression of electrons introduces significant analytical error. Only a 3 MeV H+ beam has been used for the quantitative analysis reported in this work. A rare suite of xenoliths, consisting of interlayered kyanite-bearing and kyanite-free eclogite, from the Roberts Victor kimberlite, Northern Cape, South Africa, was prepared as polished thin-sections and analyzed by the proton microprobe as a pilot study of trace element signatures in its component minerals (garnet, clinopyroxene and kyanite). The analysis of these eclogites identified significant chemical differences between the minerals of the kyanite-bearing and kyanite-free eclogite. Two clear groupings were distinguished well outside statistical error for Mn, Zn and Zr in garnet, and Mn, Ga, Sr and Ba in the clinopyroxene. Furthermore, clear chemical gradients in the elements Mn, Fe, Zn, Y and Zr were identified in single garnets at the contact between the two eclogite types. True elemental imaging revealed a heterogeneous distribution of the elements Sr and Ba in the clinopyroxene; the presence of Ba is interpreted to indicate the introduction of foreign material. A compositional dependence of the partitioning of Zn between garnet and clinopyroxene was also identified. The data do not contradict a previous hypothesis that the kyanite eclogite zones are the metamorphic products of a plagioclase-rich crystal protolith, but they do challenge the proposal that the layering is a primary feature of the rock, diffusion calculations show that these gradients were created in a geologically short time prior to kimberlite emplacement.

van Achterbergh, E.; Ryan, C. G.; Gurney, J. J.; Le Roex, A. P.

1995-09-01

86

Design and evaluation of a radio frequency coil for nuclear magnetic resonance imaging of fluorine and protons.  

PubMed

A frequency-switchable, homogeneous-field rf saddle coil has been designed for imaging both protons (1H, 59.1 MHz) and fluorine (19F, 55.6 MHz) on a 1.4-T superconducting small-bore nuclear magnetic resonance imager. Frequency and impedance switching is accomplished by external capacitance and cable length changes; these operations permit imaging of both nuclei without perturbing the sample. The coil is optimized for 19F operation, yet performs better at the proton frequency than does the unswitched 19F coil. The angular distribution of the coil's wires and the use of distributed capacitors are designed to optimize field homogeneity and Q. A quantitative image of field homogeneity is presented. The coil is suitable for imaging small animals (7-cm-diam bore) and couples far better to small samples than does our standard receiver coil (15.2 cm in diameter). Images of phantoms and rats injected with a perfluorinated blood substitute are presented. PMID:4079857

Joseph, P M; Fishman, J E

87

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

Microsoft Academic Search

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

Katia Parodi; Harald Paganetti; Ethan Cascio; Jacob B. Flanz; Ali A. Bonab; Nathaniel M. Alpert; Kevin Lohmann; Thomas Bortfeld

2007-01-01

88

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

Microsoft Academic Search

Proton relaxation time measurements were performed on a standard whole body MR imager operating at 1.5 T using a conventional surface coil of the manufacturer. A combined CP\\/CPMG multiecho, multislice sequence was used for the T1 and T2 relaxation time measurements. Two repetition times of 2000 ms (30 echoes) and 600 ms (2 echoes) with 180 degrees-pulse intervals of 2

Lothar R. Schad; Gunnar Brix; Wolfhard Semmler; F. L. Gueckel; Walter J. Lorenz

1989-01-01

89

Water management diagnostics of a proton exchange membrane fuel cell using Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

Water management presents a critical challenge to fuel cell technology. A major obstacle is the lack of in situ experimental data In this work, a Magnetic Resonance Imaging (MRI) is used as a diagnostic tool to study water distribution in an operating fuel cell and discover unexpected water transport phenomena. For the first time, quantitative water distribution data is gathered for the flow fields of an operating Proton Exchange Membrane (PEM) fuel cell. Several critical discoveries are made. First, experimental data verifies that wavy-stratified flow is the dominate flow regime in the cathode flow channels. This is in contrast to the common literature assumption that assumes the slug flow regime A fuel cell design that assumes the wrong water flow regime can suffer significant issues. Consequences include reduction in the fuel cell's freeze resistance, degraded catalyst stability, and poor stack stability and performance. A second discovery is experimental evidence for the eruptive transport by hydraulic pressure mechanism for water transport through the diffusion layer. This is the first experimental validation of this transport theory from an operating fuel cell with realistic surface characteristics. By understanding the diffusion layer transport mechanisms, new diffusion layers can be designed to better control water management. A final finding is that surface defects in the flow field impact the water distribution pattern. To the author's knowledge, this is the first time the importance of flow field surface quality is considered, and its impact is found to be profound. In our system we find that defects act as 'sticking' points on the flow channel bottom, creating water waves that do not exhaust from the fuel cell. These stuck waves increase the pressure drop within the fuel cell, as well as reducing its freeze resistance, catalyst stability, and stack stability.

Dunbar, Zachary W.

90

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

PubMed

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

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

2012-08-20

91

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

PubMed

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

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

2012-06-23

92

Three-dimensional amide proton transfer MR imaging of gliomas: Initial experience and comparison with gadolinium enhancement.  

PubMed

PURPOSE: To investigate the feasibility of a three-dimensional amide-proton-transfer (APT) imaging sequence with gradient- and spin-echo readouts at 3 Tesla in patients with high- or low-grade gliomas. MATERIALS AND METHODS: Fourteen patients with newly diagnosed gliomas were recruited. After B(0) 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 postcontrast T(1) -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. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc. 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

2013-02-25

93

Global auroral proton precipitation observed by IMAGE-FUV: Noon and midnight brightness dependence on solar wind characteristics and IMF orientation  

NASA Astrophysics Data System (ADS)

The brightness of proton aurora observed near solar maximum at summer and winter solstices with the FUV-SI12 global imager on board the IMAGE satellite has been correlated with the solar wind and the interplanetary magnetic field characteristics measured by ACE satellite instruments. By contrast to the electron aurora, we find a strong correlation both on nightside and dayside between the proton precipitated power and the solar wind dynamic pressure calculated with 1-hour averaged solar wind data. For both southward and northward IMF, the proton power increases with ?Bz?, but much more rapidly on the nightside for southward IMF orientation. Correlations for the nightside aurora were also calculated with a series of solar wind-magnetosphere coupling functions. We find highest correlation coefficients for expressions containing the dynamic pressure or involving the solar wind electric field in the Y-Z plane. The influence of the solar wind dynamic pressure on the proton aurora is tentatively explained by the effect of the pressure on the shape of the magnetosphere, generating stretching of the magnetotail and proton precipitation but also by other coupling processes between the solar wind and the magnetosphere. Adding FUV-WIC and SI13 electron aurora images in the study, we determine how proton and electron precipitations simultaneously react to solar wind and IMF characteristics and Kp. Results shows that protons are more reactive to dynamic pressure variations than electrons when Bz is positive, while the influence on of both types of particles is similar for negative Bz. The precipitating proton flux is found proportionally larger compared with the electron flux when the total auroral flux increases for low activity level. Instead, for high activity level, the proportion of the proton and the electron powers are similar when auroral power increases. Consequently, it is suggested that similar mechanisms cause proton and electron auroral precipitation for high activity levels, while they appear somewhat decoupled for lower activity conditions.

Coumans, ValéRie; GéRard, Jean-Claude; Hubert, Benoã®T.; Meurant, Matthieu

2006-05-01

94

Proton Radiography  

NASA Astrophysics Data System (ADS)

Although proton radiography has been studied in the past as an alternative to X-rays, relatively poor position resolution and expense have counterbalanced the dose advantage of protons. More recently we have shown that many of the advantages of protons as a radiographic probe can be realized by using a magnetic lens to focus the transmitted proton beam. Some potential advantages of protons over conventional X-ray techniques for flash radiography of thick, dense, dynamic systems include: 1) high penetrating power, 2) high detection efficiency, 3) small scattered background, 4) no need for a conversion target and the consequent phase space broadening of the beam, 5) inherent multi-pulse capability, and 6) large stand-off distances from the test object and containment vessel to the detectors. Additionally, the use of magnetic lens with thin detectors allows multiple images on a single axis though progressively smaller apertures to be used to vary the magnitude and Z-dependence of the interaction and can provide material identification. I will present data from experiments performed at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory and at the LANSCE accelerator at Los Alamos National Laboratory aimed at demonstrating proton radiography with a high-energy proton beams.

Morris, Christopher L.

1998-04-01

95

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

96

Proton magnetic resonance imaging of diffusion of high- and low-molecular-weight contrast agents in opaque porous media saturated with water  

Microsoft Academic Search

Besides their use in contrast-enhanced proton magnetic resonance imaging (MRI), contrast agents were found to be useful as tracer molecules. Since paramagnetic ions in water have the ability to reduce the T1 of protons around them, MRI can determine the locations of Mn2+ and Gd3+ of ppm concentration in water. In opaque porous media saturated with water, MRI revealed diffusional

T Osuga; S Han

2004-01-01

97

Use of cross-linked hydrogel materials as image contrast agents in proton nuclear magnetic resonance tomography and tissue phantom kits containing such materials  

SciTech Connect

This patent describes a method of contrasting a proton NMR tomograph of the gastro-intestinal tract, or a portion thereof, by administering enterally to a mammal an effective image contrasting amount of a physiologically tolerable, synthetic, substantially nondegradable cross-linked hydrogel having, in the aqueous swollen state, spin-lattice or spin-spin relaxation values substantially shorter than the surrounding gastro-intestinal tissue environment; and subjecting the mammal to the proton NMR tomography.

Becall, P.T.

1988-03-08

98

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.

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

2010-01-01

99

In Vivo Proton Relaxation Times Analysis of the Skin Layers by Magnetic Resonance Imaging  

Microsoft Academic Search

If in vivo magnetic resonance imaging is nowadays a powerful non-invasive method in medical diagnosis, its application in order to study the skin in vivo is not yet in common use because skin imaging requires a high resolution, at least in the direction perpendicular to the skin surface. We have therefore designed a specific imaging module, which, connected to a

Stéphanie Richard; Bernard Querleux; Jacques Bittoun; Ilana Idy-Peretti; Odile Jolivet; Eva Cermakova; Jean-Luc Lévêque

1991-01-01

100

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

PubMed

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

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

2013-05-29

101

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

102

Comprehensive longitudinal characterization of canine muscular dystrophy by serial NMR imaging of GRMD dogs.  

PubMed

The Golden Retriever Muscular Dystrophy (GRMD) dog is the closest animal counterpart of Duchenne muscular dystrophy in humans and has, for this reason, increasingly been used in preclinical therapeutic trials for this disease. The aim of this study was to describe the abnormalities in canine dystrophic muscle non-invasively, quantitatively, thoroughly and serially by means of NMR imaging. Thoracic and pelvic limbs of five healthy and five GRMD dogs were imaged in a 3T NMR scanner at 2, 4, 6 and 9months of age. Standard and fat-saturated T(1)-, T(2)- and proton-density-weighted images were acquired. A measurement of T(1) and a two-hour kinetic study of muscle enhancement after gadolinium-chelate injection were also performed. Ten out of the 15 indices evaluated differed between healthy and GRMD dogs. The maximal relative enhancement after gadolinium injection and the proton-density-weighted/T(2)-weighted signal ratio were the most discriminating indices. Inter-muscle heterogeneity was found to vary significantly for most of the indices. The body of data that has been acquired here will help in designing and interpreting preclinical trials using dystrophin-deficient dogs. PMID:22980771

Thibaud, J-L; Azzabou, N; Barthelemy, I; Fleury, S; Cabrol, L; Blot, S; Carlier, P G

2012-10-01

103

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

PubMed

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

Osuga, T; Obata, T; Ikehira, H

2004-04-01

104

Proton MR Spectroscopic Imaging Depicts Diffuse Axonal Injury in Children with Traumatic Brain Injury  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) after traumatic brain injury (TBI) is important in patient assessment and prognosis, yet they are underestimated with conventional imaging techniques. We used MR spectroscopic imaging (MRSI) to detect DAI and determine whether metabolite ratios are accurate in predicting long-term outcomes and to examine regional differences in injury between children with TBI and control

Barbara A. Holshouser; Karen A. Tong; Stephen Ashwal

105

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

PubMed Central

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

Ortega, Richard; Deves, Guillaume; Carmona, Asuncion

2009-01-01

106

NOTE: Absolute dose reconstruction in proton therapy using PET imaging modality: feasibility study  

NASA Astrophysics Data System (ADS)

A simple analytical model is developed that allows efficient absolute dose reconstruction in patients undergoing radiation treatments using proton beams. The model is based on the solution of the inverse problem of dose recovery from the 3D information contained in the PET signal, obtained immediately after the treatment. The core of the proposed model lies in the analytical calculation of the introduced positron emitters' species matrix (PESM) or kernel, facilitated by previously developed theoretical calculations of the proton energy fluence distribution. Once the PESM is known, the absolute dose distribution in a patient can be found from the deconvolution of the 3D activity distribution obtained from the PET scanner with the calculated species matrix. As an example, we have used FLUKA Monte Carlo code to simulate the delivery of the radiation dose to a tissue phantom irradiated by a parallel-opposed beam arrangement and calculated the resultant total activity. Deconvolution of the calculated activity with the PESM leads to the reconstructed dose being within 2% of that delivered.

Fourkal, E.; Fan, J.; Veltchev, I.

2009-06-01

107

A New Measurement of Cosmic Ray Protons at Energies above 20 Gev/n Rich-II Ring Imaging Cerenkov)  

NASA Astrophysics Data System (ADS)

A detailed description of a new balloon-borne cosmic ray instrument and the results from its flight are presented in this thesis. The instrument, named RICH-II, is the second in the series of ring-imaging Cerenkov counters developed at the University of Chicago for use in cosmic ray studies. In 1991, the first instrument (RICH-I) successfully measured the energy spectra of the light and medium cosmic rays. For RICH-II, a number of significant improvements have been implemented to the original instrument to improve its sensitivity to the lightest nuclei. The observational goal of RICH-II is a measurement of the energy spectra of the cosmic ray protons and helium nuclei in the energy range between 20 and 200 GeV per nucleon. Over this energy range these spectra have yet to be measured with an accuracy that is sufficient to test subtle predictions on the acceleration mechanism of these particles. In particular, detailed Monte Carlo simulations indicate small but significant differences between the proton and helium spectral indexes as a result of the shock acceleration process due to the different mass to charge ratios of these nuclei. The mission for the RICH-II instrument is to use the ring imaging technique to measure the spectral indices of these two nuclei with a degree of accuracy never before achieved in this energy range. The organization of this dissertation is as follows. The first chapter discusses the motivation of this work by providing an overview of theories of cosmic ray acceleration. Next, Chapter 2 contains an overview of the experiment and a description of the ring imaging Cerenkov technique for measuring particle energies. The following two chapters then go into significant detail about the design and performance of the individual detector systems: scintillators, hodoscope, and RICH counter. Chapter 5 briefly describes the 1996 balloon flight and the details associated with flying a balloon-borne payload. Finally, the method of data analysis, final results, and conclusions from this work are presented in Chapters 6, 7, and 8, respectively.

Ellithorpe, Don Wise

1998-11-01

108

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

2007-08-11

109

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

110

Proton magnetic resonance imaging for assessment of lung function and respiratory dynamics.  

PubMed

Since many pulmonary diseases present with a variable regional involvement, modalities for assessment of regional lung function gained increasing attention over the last years. Together with lung perfusion and gas exchange, ventilation, as a result of the interaction of the respiratory pump and the lungs, is an indispensable component of lung function. So far, this complex mechanism is still mainly assessed indirectly and globally. A differentiation between the individual determining factors of ventilation would be crucial for precise diagnostics and adequate treatment. By dynamic imaging of the respiratory pump, the mechanical components of ventilation can be assessed regionally. Amongst imaging modalities applicable to this topic, magnetic resonance imaging (MRI), as a tool not relying on ionising radiation, is the most attractive. Recent advances in MRI technology have made it possible to assess diaphragmatic and chest wall motion, static and dynamic lung volumes, as well as regional lung function. Even though existing studies show large heterogeneity in design and applied methods, it becomes evident that MRI is capable to visualise pulmonary function as well as diaphragmatic and thoracic wall movement, providing new insights into lung physiology. Partly contradictory results and conclusions are most likely caused by technical limitations, limited number of studies and small sample size. Existing studies mainly evaluate possible imaging techniques and concentrate on normal physiology. The few studies in patients with lung cancer and emphysema already give a promising outlook for these techniques from which an increasing impact on improved and quantitative disease characterization as well as better patient management can be expected. PMID:17889475

Eichinger, Monika; Tetzlaff, Ralf; Puderbach, Michael; Woodhouse, Neil; Kauczor, H-U

2007-09-21

111

Proton therapy  

MedlinePLUS

... special particles called protons. Doctors can better aim proton beams onto a tumor, so there is less damage ... tumor and outline the angles at which the proton beams will enter your body. Proton therapy is performed ...

112

Proton radiography for clinical applications  

NASA Astrophysics Data System (ADS)

Proton imaging is not yet applied as a clinical routine, although its advantages have been demonstrated. In the context of quality assurance in proton therapy, proton images can be used to verify the correct positioning of the patient and to control the range of protons. Proton computed tomography (pCT) is a 3D imaging method appropriate for planning and verification of proton radiation treatments, because it allows evaluating the distributions of proton stopping power within the tissues and can be directly utilized when the patient is in the actual treatment position. The aim of the PRoton IMAging experiment, supported by INFN, and the PRIN 2006 project, supported by MIUR, is to realize a proton computed radiography (pCR) prototype for reconstruction of proton images from a single projection in order to validate the technique with pre-clinical studies and, eventually, to conceive the configuration of a complete pCT system. A preliminary experiment performed at the 250 MeV proton synchrotron of Loma Linda University Medical Center (LLUMC) allowed acquisition of experimental data before the completion of PRIMA project's prototype. In this paper, the results of the LLUMC experiment are reported and the reconstruction of proton images of two phantoms is discussed.

Talamonti, C.; Reggioli, V.; Bruzzi, M.; Bucciolini, M.; Civinini, C.; Marrazzo, L.; Menichelli, D.; Pallotta, S.; Randazzo, N.; Sipala, V.; Cirrone, G. A. P.; Petterson, M.; Blumenkrantz, N.; Feldt, J.; Heimann, J.; Lucia, D.; Seiden, A.; Williams, D. C.; Sadrozinski, H. F.-W.; Bashkirov, V.; Schulte, R.

2010-01-01

113

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

114

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

PubMed Central

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

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

2009-01-01

115

Quantitative Proton Spectroscopic Imaging of the Neurochemical Profile in Rat Brain with Microliter Resolution at Ultra-short Echo Times  

PubMed Central

Proton spectroscopy allows the simultaneous quantification of a high number of metabolite concentrations termed the neuro-chemical profile. The spin echo full intensity acquired localization (SPECIAL) scheme with an echo time of 2.7 ms was used at 9.4T for excitation of a slab parallel to a home-built quadrature surface coil in conjunction with phase encoding in the two remaining spatial dimensions to yield an effective spatial resolution of 1.7 ?L. The absolute concentrations of at least 10 metabolites were calculated from the spectra of individual voxels using LCModel analysis. The calculated concentrations were used for constructing quantitative metabolic maps of the neurochemical profile in normal and pathological rat brain. Summation of individual spectra was used to assess the neurochemical profile of unique brain regions, such as corpus callosum, in rat for the first time. Following focal ischemia in rat pups, imaging the neurochemical profile indicated increased choline groups in the ischemic core and increased glutamine in the penumbra, which is proposed to reflect glutamate excitotoxicity. We conclude that it is feasible to achieve a sensitivity that is sufficient for quantitative mapping of the neurochemical profile at microliter spatial resolution.

Mlynarik, Vladimir; Kohler, Ingrid; Gambarota, Giulio; Vaslin, Anne; Clarke, Peter G.H.; Gruetter, Rolf

2008-01-01

116

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

117

The role of gray and white matter segmentation in quantitative proton MR spectroscopic imaging.  

PubMed

Since the brain's gray matter (GM) and white matter (WM) metabolite concentrations differ, their partial volumes can vary the voxel's ¹H MR spectroscopy (¹H-MRS) signal, reducing sensitivity to changes. While single-voxel ¹H-MRS cannot differentiate between WM and GM signals, partial volume correction is feasible by MR spectroscopic imaging (MRSI) using segmentation of the MRI acquired for VOI placement. To determine the magnitude of this effect on metabolic quantification, we segmented a 1-mm³ resolution MRI into GM, WM and CSF masks that were co-registered with the MRSI grid to yield their partial volumes in approximately every 1 cm³ spectroscopic voxel. Each voxel then provided one equation with two unknowns: its i- metabolite's GM and WM concentrations C(i) (GM) , C(i) (WM) . With the voxels' GM and WM volumes as independent coefficients, the over-determined system of equations was solved for the global averaged C(i) (GM) and C(i) (WM) . Trading off local concentration differences offers three advantages: (i) higher sensitivity due to combined data from many voxels; (ii) improved specificity to WM versus GM changes; and (iii) reduced susceptibility to partial volume effects. These improvements made no additional demands on the protocol, measurement time or hardware. Applying this approach to 18 volunteered 3D MRSI sets of 480 voxels each yielded N-acetylaspartate, creatine, choline and myo-inositol C(i) (GM) concentrations of 8.5?±?0.7, 6.9?±?0.6, 1.2?±?0.2, 5.3?±?0.6 mM, respectively, and C(i) (WM) concentrations of 7.7?±?0.6, 4.9?±?0.5, 1.4?±?0.1 and 4.4?±?0.6mM, respectively. We showed that unaccounted voxel WM or GM partial volume can vary absolute quantification by 5-10% (more for ratios), which can often double the sample size required to establish statistical significance. PMID:22714729

Tal, Assaf; Kirov, Ivan I; Grossman, Robert I; Gonen, Oded

2012-06-20

118

GLUTAMATE AS A MARKER OF COGNITIVE FUNCTION IN SCHIZOPHRENIA: A PROTON SPECTROSCOPIC IMAGING STUDY AT 4 TESLA  

PubMed Central

Background Cognitive deficits in schizophrenia may be related to glutamatergic dysfunction, but in-vivo measurement of glutamate metabolism has been challenging. We examined the relationship between glutamate metabolism and cognitive function in schizophrenia. Methods Thirty subjects with DSM-IV schizophrenia and 28 healthy volunteers, were studied using 4 Tesla proton echo planar spectroscopic imaging. Glutamate plus glutamine (Glx), N-acetyl-aspartate compounds (NAAc) and Inositol (Ins) concentrations in gray and white matter and broad neuropsychological function were assessed in all subjects. Results Glx was positively correlated with overall cognitive performance in the schizophrenia group (p=0.0006), accounting for about 36% of the variance. No correlation was found in controls. Group-averaged Glx levels were similar in schizophrenia and controls. NAAc was reduced in cortical gray matter in the younger schizophrenia subjects (age <30; p=0.04) compared to age-matched controls. Ins was increased in cortical gray (p=0.002) and white matter (p=0.02) in the older schizophrenia subjects (age>30) compared to age-matched controls. Conclusions Although not reduced in schizophrenia as a group, lower Glx levels correlates with impaired cognition in the illness. This suggests heterogeneity in mechanisms that regulate glutamate function in schizophrenia. Patients with reduced glutamatergic reserves may be rendered into a more severe hypoglutamatergic state with cognitive consequences. Reduced cortical gray matter NAAc concentration early in the illness with normalization in older subjects, is consistent with a process of early dendritic retraction with subsequent increased neuronal packing. Later in the illness, Ins elevation suggests glial involvement.

Bustillo, Juan R.; Chen, Hongji; Gasparovic, Charles; Mullins, Paul; Caprihan, Arvind; Qualls, Clifford; Apfeldorf, William; Lauriello, John; Posse, Stefan

2010-01-01

119

Part 2: Quantitative proton T2 and sodium MR imaging to assess intervertebral disc degeneration in a rabbit model  

PubMed Central

Study Design Comparison of sodium concentration ([23Na]) and proton T2 relaxation time between normal and degenerated discs in a rabbit model. Objective The purpose of this article is to evaluate quantitative [23Na] and T2 characteristics of discs associated with degenerative changes. Summary of Background Data Intervertebral disc degeneration (IDD) is a common chronic condition that may lead to back pain, limited activity, and disability. Non-invasive imaging method to detect early IDD is vital to follow disease progression and guide clinical treatment and management. Methods Dual-tuned (DT) MRI of rabbit discs was performed using a 3T. Thirteen rabbits were included in the study; six control rabbits (24 normal discs) and seven rabbits with annular-puncture-induced disc degeneration (9 degenerated discs, 19 intact internal-control discs). DT MRI of discs were performed at baseline and 12-week post-stab. [23Na] and T2 were measured and compared among three groups of discs. Results The mean [23Na] were 274.8 ± 40.2 mM for the normal discs, 247.2 ± 27.7 mM for the internal-control discs, and 190.6 ± 19.1 mM for the degenerated discs. The corresponding T2 for three groups were: 97.1 ± 12.1 ms, 93.7 ± 11.9 ms, and 79.0 ± 9.1 ms, respectively. The [23Na] is highly correlated with the T2 in the degenerated discs (r = 0.90, P < 0.01). The mean percent decrease from the normal to degenerated discs were in 30.6% in [23Na] and 18.6% in T2, while those from the internal-control to degenerated discs were 22.9% in [23Na] and 15.6% in T2. Conclusion While both [23Na] and T2 changes in discs were associated with the disc-punctured rabbits, greater change in [23Na] is observed at 12-week post-stab compared to T2 change. Since T2 and [23Na] reflect different disc properties, performing both imaging under same condition will be helpful in the evaluation of disc degeneration.

Moon, Chan Hong; Jacobs, Lloydine; Kim, Jung-Hwan; Sowa, Gwendolyn; Vo, Nam; Kang, James; Bae, Kyongtae Ty

2012-01-01

120

Dose perturbations and image artifacts caused by carbon-coated ceramic and stainless steel fiducials used in proton therapy for prostate cancer  

NASA Astrophysics Data System (ADS)

Image-guided radiation therapy using implanted fiducial markers is a common solution for prostate localization to improve targeting accuracy. However, fiducials that are typically used for conventional photon radiotherapy cause large dose perturbations in patients who receive proton radiotherapy. A proposed solution has been to use fiducials of lower atomic number (Z) materials to minimize this effect in tissue, but the effects of these fiducials on dose distributions have not been quantified. The objective of this study was to analyze the magnitude of the dose perturbations caused by select lower-Z fiducials (a carbon-coated zirconium dioxide fiducial and a plastic-coated stainless steel fiducial) and compare them to perturbations caused by conventional gold fiducials. Sets of phantoms were used to assess select components of the effects on dose. First, the fiducials were assessed for radiographic visibility using both conventional computed tomography (CT) and an on-board kilovoltage imaging device at our proton therapy center. CT streak artifacts from the fiducials were also measured in a separate phantom. Second, dose perturbations were measured downstream of the fiducials using radiochromic film. The magnitude of dose perturbation was characterized as a function of marker material, implantation depth and orientation with respect to the beam axis. The radiographic visibility of the markers was deemed to be acceptable for clinical use. The dose measurements showed that the perpendicularly oriented zirconium dioxide and stainless steel fiducials located near the center of modulation of the proton beam perturbed the dose by less than 10%, but that the same fiducials in a parallel orientation near the end of the range of the beam could perturb the dose by as much as 38%. This suggests that carbon-coated and stainless steel fiducials could be used in proton therapy if they are located far from the end of the range of the beam and if they are oriented perpendicular to the beam axis.

Cheung, Joey; Kudchadker, Rajat J.; Zhu, X. Ronald; Lee, Andrew K.; Newhauser, Wayne D.

2010-12-01

121

Proton radiography in plasma  

NASA Astrophysics Data System (ADS)

Generation of high intensity and well collimated multi-energetic proton beams from laser-matter interaction extends the possibility to use protons as a diagnostic tool to image imploding target in Inertial Confinement Fusion (ICF) experiments. Due to the very large mass densities reached during implosion, protons traveling through the target undergo a very large number of collisions. Therefore the analysis of experimentally obtained proton images requires care and accurate numerical simulations using both hydrodynamic and Monte Carlo codes. The impact of multiple scattering needs to be carefully considered by taking into account the exact stopping power for dense matter and for the underdense plasma corona. In our paper, density, temperature and ionization degree profiles of the imploding target are obtained by 2D hydrodynamic simulations performed using CHIC code. Proton radiography images are simulated using the Monte Carlo code (MCNPX; adapted to correctly describe multiple scattering and plasma stopping power) in order to reconstruct the complete hydrodynamic history of the imploding target. Finally we develop a simple analytical model to study the performance of proton radiography as a function of initial experimental parameters, and identify two different regimes for proton radiography in ICF.

Volpe, L.; Batani, D.; Morace, A.; Nicolai, Ph.; Regan, C.; Ravasio, A.

2011-10-01

122

Physical Image vs. Structure Relation. Part 3 [1]. Basic Properties and Protonation Mechanism of Some Tetraaza Macrocyclic Ligands  

Microsoft Academic Search

The protonation constants, log K, for 1,4,7,11-tetraazacyclotetradecane (isocyclam, 2), 1-(2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane (scorpiand, 3), 5,12-dimethyl-1,4,8,11-tetraazacyclotetradecane (Me2cyclam, 4) and 5,5,7,12,14,14-hexamethyl-1,4,8,11- tetraazacyclotetradecane (Me6cyclam, 5) were determined pH-metrically. Attempts of correlation of the calculated enthalpy of protonation in the gas phase (AM1 method) with experimental values of the protonation constants for ligands 1, 2, 4–7 were done 1,4,8,11-tetraazacyclotetradecane, cyclam, 1; 1,4,7,10-tetraazacyclotetradecane, cyclen, 6; 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, (N-Me)4cyclam,

Ryszard B. Nazarski

1999-01-01

123

Cobalt 60 and proton radiation effects on large format, 2-D, CCD arrays for an earth imaging application  

NASA Astrophysics Data System (ADS)

Cobalt 60 and 10-MeV proton irradiations have been carried out on n-buried channel frame transfer CCDs (charge coupled devices) in order to study changes in charge transfer efficiency (CTE) and dark current for room temperature, 1 microsec/pixel, readout conditions. Bias dependence and postannealing effects were observed for ionization damage. CTE effects are explained in terms of capture and emission from deep level traps. Temporal instabilities (random telegraph signals) were observed in the proton-induced dark current.

Hopkinson, G. R.

1992-12-01

124

Prostate and lymph node proton magnetic resonance (MR) spectroscopic imaging with external array coils at 3 T to detect recurrent prostate cancer after radiation therapy.  

PubMed

In a patient suspected of having recurrent prostate cancer after radiation therapy, we demonstrate the feasibility of noninvasive proton magnetic resonance spectroscopic (1H-MRS) imaging of the prostate and a lymph node at 3 T using a matrix of external surface coils. Written informed consent was obtained from the patient. With 1H-MRS imaging, high choline with low citrate signal was observed in the prostate, and in the lymph node a signal of choline-containing compounds was identified. The tissue level of the compounds in the enlarged lymph node was estimated to be 8.1 mmol/kg water. Subsequent histopathological analysis of systematic transrectal ultrasound-guided prostate biopsy and computed tomography-guided biopsy of the lymph node confirmed the presence of prostate cancer in both. PMID:17507814

Heijmink, Stijn W T P J; Scheenen, Tom W J; Fütterer, Jurgen J; Klomp, Dennis W J; Heesakkers, Roel A M; Hulsbergen-van de Kaa, Christina A; van Lin, Emile N J Th; Heerschap, Arend; Barentsz, Jelle O

2007-06-01

125

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

126

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

PubMed Central

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

Wang, Yi; Efstathiou, Jason A.; Sharp, Gregory C.; Lu, Hsiao-Ming; Frank Ciernik, I.; Trofimov, Alexei V.

2011-01-01

127

[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

128

Proton Therapy  

MedlinePLUS

... up? Login here Please leave this field empty Proton Therapy SHARE Share on Facebook Preview your comments ... a nucleus, which holds two types of particles—protons and neutrons. The nucleus is surrounded by electrons. ...

129

Enantioselective Protonation  

PubMed Central

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

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

2010-01-01

130

T1 weighted Brain Images at 7 Tesla Unbiased for Proton Density, T2* contrast and RF Coil Receive B1 Sensitivity with Simultaneous Vessel Visualization  

PubMed Central

At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as “intensity field bias”. Such inhomogeneities mostly originate from heterogeneous RF coil B1 profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T1-weighted (T1w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T1 weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T1 contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B1 variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B1 profiles become more heterogeneous. Another characteristic of T1w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T2* contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T1w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T2* contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 Tesla, provide higher T1 contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help identifying small brain structures and that T2* induced artifacts can be removed from the images. The resulting unbiased T1w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T1w structural images. In addition, we introduce a simple technique to reduce residual signal intensity variations induced by Transmit B1 heterogeneity. Because this approach requires two 3D images, one divided with the other, head motion could create serious problems, especially at high spatial resolution. To alleviate such inter-scan motion problems, we developed a new sequence where the two contrast acquisitions are interleaved within a single scan. This interleaved approach however comes with greater risk of intra-scan motion issues because of a longer single scan time. Users can choose between these two trade offs depending on specific protocols and patient populations. We believe that the simplicity and the robustness of this double contrast based approach to address intensity field bias at high field and improve T1 contrast specificity, together with the capability of simultaneously obtaining angiography maps, advantageously counter balance the potential drawbacks of the technique, mainly a longer acquisition time and a moderate reduction in signal to noise ratio.

Van de Moortele, Pierre-Francois; Auerbach, Edwards J.; Olman, Cheryl; Yacoub, Essa; Ugurbil, Kamil; Moeller, Steen

2009-01-01

131

NOTE: Sequential, co-registered fluorine and proton field-cycled Overhauser imaging at a detection field of 59 mT  

NASA Astrophysics Data System (ADS)

In this work we show the feasibility of sequential, co-registered fluorine and proton field-cycled Overhauser imaging at a detection field of 59 mT. To this purpose we have built an RF coil assembly comprising an Alderman Grant resonator for EPR irradiation at 127.7 MHz (evolution field of 4.5 mT) and a solenoidal coil for 19F or 1H MRI acquisition at the detection field of 59 mT. A removable tuning/matching circuit that allows the solenoid to be tuned to the 19F frequency (2.346 MHz, FEDRI) or the 1H frequency (2.494 MHz, PEDRI) without removing the sample was built and tested. Switching of the solenoid between the 19F and 1H frequency is thus achieved in less than 1 min. The co-registered FC-FEDRI and FC-PEDRI images show higher enhancement in the sample regions with higher free radical concentration. This work is the first methodological step towards the development of an MRI scanner capable of acquiring morphological (1H) and physiological (19F) images in animal models at very low fields.

Modica, Alessandro; Lurie, David J.; Alecci, Marcello

2006-02-01

132

Sequential, co-registered fluorine and proton field-cycled Overhauser imaging at a detection field of 59 mT.  

PubMed

In this work we show the feasibility of sequential, co-registered fluorine and proton field-cycled Overhauser imaging at a detection field of 59 mT. To this purpose we have built an RF coil assembly comprising an Alderman-Grant resonator for EPR irradiation at 127.7 MHz (evolution field of 4.5 mT) and a solenoidal coil for (19)F or (1)H MRI acquisition at the detection field of 59 mT. A removable tuning/matching circuit that allows the solenoid to be tuned to the (19)F frequency (2.346 MHz, FEDRI) or the (1)H frequency (2.494 MHz, PEDRI) without removing the sample was built and tested. Switching of the solenoid between the (19)F and (1)H frequency is thus achieved in less than 1 min. The co-registered FC-FEDRI and FC-PEDRI images show higher enhancement in the sample regions with higher free radical concentration. This work is the first methodological step towards the development of an MRI scanner capable of acquiring morphological ((1)H) and physiological ((19)F) images in animal models at very low fields. PMID:16424574

Modica, Alessandro; Lurie, David J; Alecci, Marcello

2006-01-11

133

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

134

Proton Therapy  

NASA Astrophysics Data System (ADS)

Proton therapy is one of the most rapidly developing new treatment technologies in radiation oncology. This treatment approach has — after roughly 40 years of technical developments — reached a mature state that allows a widespread clinical application. We therefore review the basic physical and radio-biological properties of proton beams. The main physical aspect is the elemental dose distribution arising from an infinitely narrow proton pencil beam. This includes the physics of proton stopping powers and the concept of CSDA range. Furthermore, the process of multiple Coulomb scattering is discussed for the lateral dose distribution. Next, the basic terms for the description of radio-biological properties of proton beams like LET and RBE are briefly introduced. Finally, the main concepts of modern proton dose delivery concepts are introduced before the standard method of inverse treatment planning for hadron therapy is presented.

Oelfke, Uwe

135

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

136

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

2013-07-09

137

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

PubMed

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

Osuga, T; Obata, T; Ikehira, H

2004-04-01

138

Effects of simulated space proton environment on transmission of optical materials for the space telescope imaging spectrograph (STIS)  

NASA Astrophysics Data System (ADS)

Potential transmitting materials for the STIS mission are being considered for order sorters, in-flight calibration filters, detector windows and calibration lamps. In this paper we examine the changes in spectral transmission characteristics with radiation dosage during a mission lifetime. A radiation environment for a 593 km altitude, 28 degree inclination orbit, for solar minimum and solar maximum, assuming a spherical shielding of 2 gms/cm2$ has been assumed. The dosage for protons is 0.392 Krad (Al/Yr. and 0.217 Krad (Al)/Yr. for solar minimum and solar maximum respectively. To simulate the mission radiation environment Harvard Cyclotron Laboratory (HCL) has been used. Spectral transmission was measured between 210 nm and 3200 nm using a Perkin Elmer Lambda 9 monochromator. Below 210 nm a one meter McPherson vacuum monochromator was used. Transmission curves for all samples were obtained before irradiation and compared for equality in transmission.

Becher, Jacob; Fowler, Walter B.

1993-10-01

139

PROTON MICROSCOPY AT FAIR  

SciTech Connect

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

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

2009-12-28

140

Comparison between high-field-strength MR imaging and CT for screening of hepatic metastases: a receiver operating characteristic analysis.  

PubMed

The diagnostic performance of high-field-strength magnetic resonance (MR) imaging (1.5 T) for detection of liver metastases was compared with that of computed tomography (CT). All patients (n = 52) underwent preoperative screening for metastases by means of MR imaging with T1-weighted, proton-density-weighted, and T2-weighted pulse sequences and CT scanning with unenhanced, incremental dynamic bolus-enhanced, and delayed contrast medium-enhanced techniques. Diagnostic performance was evaluated by means of receiver operating characteristic analysis in which 800 images (400 with and 400 without lesions) and five readers (4,000 observations) were used; images were obtained from patients (n = 39) in whom the same anatomic levels were available for all MR imaging and CT studies. Direct comparison between the best MR imaging technique (T2-weighted spin-echo imaging [repetition time, 2,000 msec; echo time, 70 msec]) and the best CT technique (incremental dynamic bolus CT) showed a strong trend of superiority of T2-weighted MR imaging over incremental dynamic bolus CT. No highly statistically significant difference (P greater than or equal to .01), however, was found between these two techniques. PMID:1535912

Rummeny, E J; Wernecke, K; Saini, S; Vassallo, P; Wiesmann, W; Oestmann, J W; Kivelitz, D; Reers, B; Reiser, M F; Peters, P E

1992-03-01

141

In vivo bone marrow lipid characterization with line scan Carr-Purcell-Meiboom-Gill proton spectroscopic imaging  

Microsoft Academic Search

Line scan Carr-Purcell-Meiboom-Gill spectroscopic imaging sequences have been used to extract lipid chemical composition indices in healthy adult bone marrow in the knee at 1.5 T. Since several spectroscopic echo readouts follow each excitation, the information acquired reflects a balance between spectral T2 decay processes and spectral resolution. To examine this balance in detail, data sets with two different echo

Robert V Mulkern; Jiqun Meng; John L Bowers; Koichi Oshio; Chun Zuo; Haicheng Li; Robert A Krafi; Daniel S Williamson; Diego Jaramillo

1997-01-01

142

Proton interrogation  

SciTech Connect

Energetic proton beams may 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 proton beams can be manipulated with magnetic optics. We have measured time-dependent cross sections for delayed neutrons and gamma-rays using the 800 MeV proton beam from the Los Alamos Neutron Science Center for a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Results will be presented.

Morris, Christopher L [Los Alamos National Laboratory

2008-01-01

143

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

PubMed Central

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

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

2013-01-01

144

Magnetic optics for proton radiography  

Microsoft Academic Search

High energy protons of 10 to 50 GeV can be used to radiograph dense objects. Because the transmitted beam particles undergo multiple Coulomb scattering (MCS) in the object, a magnetic lens system is used to focus the particles exiting each point of the object onto a distant image plane. Without the lens, the MCS would seriously blur the radiographic image.

C. Thomas Mottershead; John D. Zumbro

1997-01-01

145

Electron and Proton Auroral Dynamics  

NASA Astrophysics Data System (ADS)

Data from the IMAGE 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 developed into a double oval configuration, consisting of a set of discrete poleward forms and a separate diffuse auroral oval equatorwards. Although IMF Bz was negative, considerable activity could be seen poleward of the high latitude arcs in the polar cap region. The optical signature of precipitating protons showed that the proton aurora was on the equatorward side of the diffuse aurora and there was a lack of intense energetic proton fluxes in the poleward arcs. A simultaneous FAST pass provided a diagnostic of the particle types in the various regions. These data showed that lower intensity protons were present throughout the entire double oval configuration but with insufficient intensity to produce aurora that could be observed by IMAGE. The FAST data also showed that the bright poleward discrete arcs were accelerated by electrostatic processes, and the wave accelerated electrons were located on the poleward edge of these features.

Mende, S. B.; Frey, H. U.; Carlson, C.; Immel, T.; Gerard, J.; Hubert, B.; Fuselier, S.; Spann, J.; Gladstone, R.; Burch, J. L.

2001-05-01

146

Cerebral gliomas: prospective comparison of multivoxel 2D chemical-shift imaging proton MR spectroscopy, echoplanar perfusion and diffusion-weighted MRI  

Microsoft Academic Search

. Developments in MRI have made it possible to use diffusion-weighted MRI, perfusion MRI and proton MR spectroscopy (MRS) to study lesions in the brain. We evaluated whether these techniques provide useful, complementary information for grading gliomas, in comparison with conventional MRI. We studied 17 patients with histologically verified gliomas, adding multivoxel proton MRS, echoplanar diffusion and perfusion MRI the

D. Yang; Y. Korogi; T. Sugahara; M. Kitajima; Y. Shigematsu; L. Liang; Y. Ushio; M. Takahashi

2002-01-01

147

Technological Advances in Proton Therapy  

NASA Astrophysics Data System (ADS)

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

McDonough, James

2008-03-01

148

Simultaneous Bilateral Magnetic Resonance Imaging of the Femoral Arteries in Peripheral Arterial Disease Patients  

PubMed Central

Purpose To image the femoral arteries in peripheral arterial disease (PAD) patients using a bilateral receive coil. Materials and Methods An eight-channel surface coil array for bilateral MRI of the femoral arteries at 3T was constructed and evaluated. Results The bilateral array enabled imaging of a 25-cm segment of the superficial femoral arteries (SFA) from the profunda to the popliteal. The array provided improved the signal-to-noise ratio (SNR) at the periphery and similar SNR in the middle of a phantom compared to three other commercially available coils (4-channel torso, quadrature head, whole body). Multicontrast bilateral images of the in vivo SFA with 1 mm inplane resolution made it possible to directly compare lesions in the index SFA to the corresponding anatomical site in the contralateral vessel without repositioning the patient or coil. A set of bilateral time-of-flight, T1-weighted, T2-weighted, and proton density-weighted images was acquired in a clinically acceptable exam time of ?45 minutes. Conclusion The developed bilateral coil is well suited for monitoring dimensional changes in atherosclerotic lesions of the SFA.

Brown, Ryan; Karmonik, Christof; Brunner, Gerd; Lumsden, Alan; Ballantyne, Christie; Johnson, Shawna; Wang, Yi; Morrisett, Joel

2013-01-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

150

An average image of proton plasma pressure and of current systems in the equatorial plane derived from AMPTE\\/CCE-CHEM measurements  

Microsoft Academic Search

The present study attempts to visualize the global equatorial current systems and the proton pressure in the near-Earth magnetosphere based on AMPTE\\/CCE-CHEM measured proton distributions, which were sorted by the AE index (``quiet'': AE<100nT, ``active'': 100nT

Paola De Michelis; Ioannis A. Daglis; Giuseppe Consolini

1999-01-01

151

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

152

Development of Proton Computed Tomography for Applications in Proton Therapy  

NASA Astrophysics Data System (ADS)

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; Erdelyi, Bela; Wong, Kent; Sadrozinski, Hartmut; Penfold, Scott; Rosenfeld, Anatoly; McAllister, Scott; Schubert, Keith

2009-03-01

153

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

154

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

PubMed Central

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

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

2013-01-01

155

Proton Therapy  

MedlinePLUS

... tuning the energy of the beam and the magnetic fields which guide their path. These modifications guide ... target the tumor. Additional exams, such as a magnetic resonance imaging (MRI), or a PET/CT scan ...

156

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

157

Proton decay theory  

Microsoft Academic Search

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

Marciano

1983-01-01

158

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

159

MRI of the Wrist at 7 Tesla using an 8 Channel Array Coil Combined with Parallel Imaging: Preliminary Results  

PubMed Central

PURPOSE To determine the feasibility of performing MRI of the wrist at 7 Tesla with parallel imaging and to evaluate how acceleration factors(AF) affect signal-to-noise ratio(SNR), contrast-to-noise ratio(CNR), and image quality. MATERIALS AND METHODS This study had institutional review board approval. A 4-transmit 8-receive channel array coil was constructed in–house. Nine healthy subjects were scanned on a 7T whole-body MR scanner. Coronal and axial images of cartilage and trabecular bone micro-architecture(3D-Fast Low Angle Shot(FLASH) with and without fat suppression, TR/TE=20ms/4.5ms, flip angle=10°, 0.169–0.195×0.169–0.195 mm, 0.5–1 mm slice thickness) were obtained with AF 1, 2, 3, 4. T1-weighted fast spin-echo(FSE), proton density-weighted FSE, and multiple-echo data image combination(MEDIC) sequences were also performed. SNR and CNR were measured. Three musculoskeletal radiologists rated image quality. Linear correlation analysis and paired t-tests were performed. RESULTS At higher AF, SNR and CNR decreased linearly for cartilage, muscle, and trabecular bone(rimages with AF 1 and 2 as near-excellent, AF 3 as good-to-excellent(p=0.075), and AF 4 as average-to-good(p=0.11). CONCLUSION It is feasible to perform high resolution 7 Tesla MRI of the wrist with parallel imaging. SNR and CNR decrease with higher AF, but image quality remains above-average.

Chang, Gregory; Friedrich, Klaus M.; Wang, Ligong; Vieira, Renata L.R.; Schweitzer, Mark E.; Recht, Michael P.; Wiggins, Graham C.; Regatte, Ravinder R.

2010-01-01

160

Proton shadow camera using CR-39 track detectors  

SciTech Connect

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

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

1983-09-01

161

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

162

Two-proton radioactivity of 45Fe  

NASA Astrophysics Data System (ADS)

The decay of the extremely neutron-deficient isotope 45Fe has been studied by using a new type of gaseous detector in which a technique of optical imaging is used to record tracks of charged particles. The two-proton radioactivity and the ? -decay channels were clearly identified. For the first time, the angular and energy correlations between two protons emitted from the 45Fe ground state were measured. The obtained results were confronted with predictions of a three-body model.

Miernik, K.; Dominik, W.; Janas, Z.; Pfützner, M.; Grigorenko, L.; Bingham, C.; Czyrkowski, H.; ?wiok, M.; Darby, I. G.; D?browski, R.; Ginter, T.; Grzywacz, R.; Karny, M.; Korgul, A.; Ku?mierz, W.; Liddick, S. N.; Rajabali, M.; Rykaczewski, K.; Stolz, A.

2009-12-01

163

-delayed proton emission branches in 43Cr  

SciTech Connect

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

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

2011-01-01

164

?-delayed proton emission branches in Cr43  

NASA Astrophysics Data System (ADS)

The ?+ decay of very neutron-deficient Cr43 was studied by means of an imaging time projection chamber that allowed recording tracks of charged particles. Events of ?-delayed emission of one, two, and three protons were clearly identified. The absolute branching ratios for these channels were determined to be (81±4)%, (7.1±0.4)%, and (0.08±0.03)%, respectively. Cr43 is thus established as the second case in which the ?-3p decay occurs. Although the feeding to the proton-bound states in V43 is expected to be negligible, the large branching ratio of (12±4)% for decays without proton emission is found.

Pomorski, M.; Miernik, K.; Dominik, W.; Janas, Z.; Pfützner, M.; Bingham, C. R.; Czyrkowski, H.; ?wiok, M.; Darby, I. G.; D?browski, R.; Ginter, T.; Grzywacz, R.; Karny, M.; Korgul, A.; Ku?mierz, W.; Liddick, S. N.; Rajabali, M.; Rykaczewski, K.; Stolz, A.

2011-01-01

165

Evaluation of mannitol effect in patients with acute hepatic failure and acute-on-chronic liver failure using conventional MRI, diffusion tensor imaging and in-vivo proton MR spectroscopy  

PubMed Central

AIM: To evaluate the effect of an intravenous bolus of mannitol in altering brain metabolites, brain water content, brain parenchyma volume, cerebrospinal fluid (CSF) volume and clinical signs in controls and in patients with acute liver failure (ALF) and acute-on-chronic liver failure (ACLF), by comparing changes in conventional magnetic resonance imaging (MRI), in vivo proton magnetic resonance spectroscopy (PMRS) and diffusion tensor imaging (DTI) before and after its infusion. METHODS: Five patients each with ALF and ACLF in grade 3 or 4 hepatic encephalopathy and with clinical signs of raised intracranial pressure were studied along with five healthy volunteers. After baseline MRI, an intravenous bolus of 20% mannitol solution was given over 10 min in controls as well as in patients with ALF and ACLF. Repeat MRI for the same position was acquired 30 min after completing the mannitol injection. RESULTS: No statistically significant difference was observed between controls and patients with ALF and ACLF in metabolite ratios, DTI metrics and brain volume or CSF volume following 45 min of mannitol infusion. There was no change in clinical status at the end of post-mannitol imaging. CONCLUSION: The osmotic effect of mannitol did not result in significant reduction of brain water content, alteration in metabolite ratios or any change in the clinical status of these patients during or within 45 min of mannitol infusion.

Saraswat, Vivek A; Saksena, Sona; Nath, Kavindra; Mandal, Pranav; Singh, Jitesh; Thomas, M Albert; Rathore, Ramkishore S; Gupta, Rakesh K

2008-01-01

166

On Some Errors and Bias in Proton Computed Tomography  

NASA Astrophysics Data System (ADS)

Novel accelerator technology, including Fixed Field Alternating Gradient Accelerators (FFAG) coupled with medical imaging devices, hold significant promise for enhanced proton therapy. The accuracy and efficiency of proton therapy treatments will see improvements with the implementation of proton computed tomography (pCT), currently under development. Here, we analyze the robustness of the image reconstruction method in pCT with respect to three different error sources and conclude that pCT is inherently resilient with respect to errors in mean ionization potential, discrete sampling of proton trajectories and bias in the limit of large radiation doses.

Erdelyi, Bela

167

Serial In vivo Spectroscopic Nuclear Magnetic Resonance Imaging of Lactate and Extracellular pH in Rat Gliomas Shows Redistribution of Protons Away from Sites of Glycolysis  

Microsoft Academic Search

The acidity of the tumor microenvironment aids tumor growth, and mechanisms causing it are targets for potential therapies. We have imaged extracellular pH (pHe) in C6 cell gliomas in rat brain using 1H magnetic resonance spectroscopy in vivo. We used a new probe molecule, ISUCA ((F)2-(imidazol- 1-yl)succinic acid), and fast imaging techniques, with spiral acquisition in k-space. We obtained a

Peggy Provent; Marina Benito; Bassem Hiba; Regine Farion; Pilar Lopez-Larrubia; Paloma Ballesteros; Chantal Remy; Christoph Segebarth; Sebastian Cerdan; Jonathan A. Coles; Maria Luisa Garcia-Martin

2007-01-01

168

On the use of a proton path probability map for proton computed tomography reconstruction1  

PubMed Central

Purpose: To describe a method to estimate the proton path in proton computed tomography (pCT) reconstruction, which is based on the probability of a proton passing through each point within an object to be imaged. Methods: Based on multiple Coulomb scattering and a semianalytically derived model, the conditional probability of a proton passing through each point within the object given its incoming and exit condition is calculated in a Bayesian inference framework, employing data obtained from Monte Carlo simulation using GEANT4. The conditional probability at all of the points in the reconstruction plane forms a conditional probability map and can be used for pCT reconstruction. Results: From the generated conditional probability map, a most-likely path (MLP) and a 90% probability envelope around the most-likely path can be extracted and used for pCT reconstruction. The reconstructed pCT image using the conditional probability map yields a smooth pCT image with minor artifacts. pCT reconstructions obtained using the extracted MLP and the 90% probability envelope compare well to reconstructions employing the method of cubic spline proton path estimation. Conclusions: The conditional probability of a proton passing through each point in an object given its entrance and exit condition can be obtained using the proposed method. The extracted MLP and the 90% probability envelope match the proton path recorded in the GEANT4 simulation well. The generated probability map also provides a benchmark for comparing different path estimation methods.

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

2010-01-01

169

Proton radiography as a tool for quality control in proton therapy.  

PubMed

Proton radiography is investigated for its use as a quality control tool in proton therapy. Images were produced both with range and range uncertainty information of protons passing through phantoms (Alderson phantom and a sheep's head). With the range images the correct positioning of the patient with respect to the beam could be verified. The range uncertainty images were used to quantitatively detect range variations of protons passing through inhomogeneities in the patient. These measurements can be used to indicate critical situations during proton therapy or to determine the safety margin around the tumor volume. With the range information the precision of different calibrations of computer tomography Hounsfield values to relative proton stopping power, used for proton treatment planning, was determined. It is found that the precision in range can be improved by a detailed analysis of the calibration data obtained from tissue-substitute measurements, by a factor of 2.5. The resulting range errors are in the order of the positioning precision (approximately 1 mm). PMID:7609715

Schneider, U; Pedroni, E

1995-04-01

170

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

171

What's In a Proton?  

ScienceCinema

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

172

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

173

Proton pump inhibitors  

MedlinePLUS

Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD), a ...

174

MR Imaging Characteristics of Tuberculous Spondylitis vs Vertebral Osteomyelitis  

Microsoft Academic Search

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

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

175

Magnetic optics for proton radiography  

SciTech Connect

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

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

1997-10-01

176

Note: A new angle-resolved proton energy spectrometer  

NASA Astrophysics Data System (ADS)

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.; Zhang, J.

2013-09-01

177

Note: A new angle-resolved proton energy spectrometer.  

PubMed

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. PMID:24089878

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; Zhang, J

2013-09-01

178

Multimodality imaging of atherosclerotic plaque activity and composition using FDG-PET/CT and MRI in carotid and femoral arteries  

PubMed Central

Purpose To evaluate the relationship between atherosclerotic plaque inflammation, as assessed by FDG-Positron Emission Tomography/Computed Tomography (FDG-PET/CT), and plaque morphology and composition, as assessed by magnetic resonance imaging (MRI), in the carotid and femoral arteries. Materials and methods Sixteen patients underwent FDG-PET/CT and MRI (T2 weighted (T2W) and Proton density weighted (PDW)) of the carotid and femoral arteries. For every image slice, two observers determined the corresponding regions of the FDG-PET/CT and MRI image sets by matching CT and T2W axial images. Each plaque was then classified into one of three groups according to the CT appearance and T2W/PDW signal: 1) collagen, 2) lipid-necrotic core and 3) calcium. Arterial FDG uptake was measured for each plaque and normalized to vein FDG activity to produce a blood-normalized artery activity called the target to background ratio (TBR). The vessel wall thickness (VWT), the vessel wall area and the total vessel wall area were measured from the T2W MR images. Results The TBR value was higher in the lipid-necrotic core group compared to the collagen and calcium groups, (p < 0.001). The lipid-necrotic core group demonstrated a significant TBR variation according to the median of the VWT (TBR = 1.26 ± 0.25 vs. TBR = 1.50 ± 0.12). There was no correlation with other morphological MR parameters. Conclusions This study demonstrates the complementary value of non-invasive FDG-PET/CT and MR imaging for the evaluation of atherosclerotic plaque composition and activity. Lipid-rich plaques are more inflamed than either calcified or collagen-rich plaques.

Silvera, Stephane S.; el Aidi, Hamza; Rudd, James H. F.; Mani, Venkatesh; Yang, Lingde; Farkouh, Michael; Fuster, Valentin; Fayad, Zahi A.

2012-01-01

179

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

PubMed Central

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

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

2011-01-01

180

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

181

Density resolution of proton computed tomography  

SciTech Connect

Conformal proton radiation therapy requires accurate prediction of the Bragg peak position. Protons may be more suitable than conventional x rays for this task since the relative electron density distribution can be measured directly with proton computed tomography (CT). However, proton CT has its own limitations, which need to be carefully studied before this technique can be introduced into routine clinical practice. In this work, we have used analytical relationships as well as the Monte Carlo simulation tool GEANT4 to study the principal resolution limits of proton CT. The noise level observed in proton CT images of a cylindrical water phantom with embedded tissue-equivalent density inhomogeneities, which were generated based on GEANT4 simulations, compared well with predictions based on Tschalar's theory of energy loss straggling. The relationship between phantom thickness, initial energy, and the relative electron density resolution was systematically investigated to estimate the proton dose needed to obtain a given density resolution. We show that a reasonable density resolution can be achieved with a relatively small dose, which is comparable to or even lower than that of x-ray CT.

Schulte, Reinhard W.; Bashkirov, Vladimir; Loss Klock, Margio C.; Li Tianfang; Wroe, Andrew J.; Evseev, Ivan; Williams, David C.; Satogata, Todd [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States); Federal Center of Technological Education in Parana State, Curitiba, PR 80230-901 (Brazil); Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States); Department of Physics and Astronomy, State University of New York Stony Brook, Stony Brook, New York 11790 (United States); Centre for Medical Radiation Physics, Wollongong University, Wollongong, NSW 2522 (Australia); Polytechnic Institute, Rio de Janeiro State University, Nova Friburgo, RJ 28630-050 (Brazil); Santa Cruz Institute of Particle Physics, UC Santa Cruz, Santa Cruz, California 95064 (United States); Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2005-04-01

182

Diagnostic value of proton MR spectroscopy and diffusion-weighted MR imaging in childhood inherited neurometabolic brain diseases and review of the literature.  

PubMed

The purpose of this study is to evaluate parenchymal diffusion properties and metabolite ratios in affected brain tissues of inherited neurometabolic brain diseases with an overview of the current literature about the diagnostic data of both techniques in childhood inherited metabolic brain diseases. The study group was consisting, 19 patients (15 males, 4 females; mean age, 54 months (4.5 years); age range, 1-171 months (14.25 years)) diagnosed with inherited neurometabolic brain disease. Single- and multivoxel proton MRS was carried out and NAA/Cr, Cho/Cr, mI/Cr, Glx/Cr ratios were calculated. Presence of lactate peak and abnormal different peaks were noted. ADC values were calculated from brain lesions. Results are compared with age and sex matched normal subjects. Elevated NAA/Cr ratio (Canavan disease), galactitol peak (galactosemia) at 3.7 ppm, branched chain amino acids (Maple syrup urine disease-MSUD) at 0.9 ppm were seen on different diseases. In Leigh disease and MSUD restricted diffusion was detected. Different diffusion properties were seen only in one Glutaric aciduria lesions. NAA/Cr ratios and calculated ADC values were significantly different from normal subjects (p<0.05). DWI combined with MRS are complementary methods to routine cranial MRI for evaluating neurometabolic diseases which can give detailed information about neurochemistry of affected brain areas. PMID:19540689

Cakmakci, Handan; Pekcevik, Yeliz; Yis, Uluc; Unalp, Aycan; Kurul, Semra

2009-06-21

183

MR Spectroscopic Changes in the Rat Hippocampus following Proton Radiosurgery  

Microsoft Academic Search

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

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

2006-01-01

184

Proton-Proton Physics with ALICE  

Microsoft Academic Search

The goal of the ALICE experiment at LHC is to study strongly interacting matter at high energy densities as well as the signatures and properties of the quark-gluon plasma. This goal manifests itself in a rich physics program. Although ALICE will mainly study heavy-ion collisions, a dedicated program will concentrate on proton-proton physics. The first part will introduce the ALICE

J. F. Grosse-Oetringhaus

2008-01-01

185

Proton-Proton Physics with ALICE  

Microsoft Academic Search

The goal of the ALICE experiment at LHC is to study strongly interacting\\u000amatter at high energy densities as well as the signatures and properties of the\\u000aquark-gluon plasma. This goal manifests itself in a rich physics program.\\u000aAlthough ALICE will mainly study heavy-ion collisions, a dedicated program will\\u000aconcentrate on proton-proton physics. The first part will introduce the ALICE

Jan Fiete Grosse-Oetringhaus

2008-01-01

186

Proton damage effects in high performance P-channel CCDs  

Microsoft Academic Search

P-channel CCDs with pre-rad imaging characteristics comparable to the best N-channel CCDs have been fabricated and tested. These devices have been subjected to proton damage and display the superior hardness predicted for them.

James P. Spratt; Chris Conger; Richard Bredthauer; Wheaton Byers; Robert Groulx; Roland Leadon; Henry Clark

2005-01-01

187

Proton damage effects in high performance P-channel CCDs  

Microsoft Academic Search

P-channel CCDs with pre-rad imaging characteristics comparable to the best N-channel CCDs have been fabricated and tested. These devices have been subjected to proton damage and display the superior hardness predicted for them.

James P. Spratt; Chris Conger; Richard Bredthauer; Wheaton Byers; Robert Groulx; Roland E. Leadon; Henry Clark

2006-01-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

189

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

190

Proton-proton reaction theory with proton polarizability.  

National Technical Information Service (NTIS)

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

V. V. Pupyshev O. P. Solovtsova

1989-01-01

191

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

192

Proton therapy dosimetry using positron emission tomography  

PubMed Central

Protons deposit most of their kinetic energy at the end of their path with no energy deposition beyond the range, making proton therapy a valuable option for treating tumors while sparing surrounding tissues. It is imperative to know the location of the dose deposition to ensure the tumor, and not healthy tissue, is being irradiated. To be able to extract this information in a clinical situation, an accurate dosimetry measurement system is required. There are currently two in vivo methods that are being used for proton therapy dosimetry: (1) online or in-beam monitoring and (2) offline monitoring, both using positron emission tomography (PET) systems. The theory behind using PET is that protons experience inelastic collisions with atoms in tissues resulting in nuclear reactions creating positron emitters. By acquiring a PET image following treatment, the location of the positron emitters in the patient, and therefore the path of the proton beam, can be determined. Coupling the information from the PET image with the patient’s anatomy, it is possible to monitor the location of the tumor and the location of the dose deposition. This review summarizes current research investigating both of these methods with promising results and reviews the limitations along with the advantages of each method.

Studenski, Matthew T; Xiao, Ying

2010-01-01

193

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

194

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

NASA Astrophysics Data System (ADS)

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

Bom, Victor; Joulaeizadeh, Leila; Beekman, Freek

2012-01-01

195

Impact of fluoxetine on the human brain in multiple sclerosis as quantified by proton magnetic resonance spectroscopy and diffusion tensor imaging.  

PubMed

The antidepressant fluoxetine stimulates astrocytic glycogenolysis, which serves as an energy source for axons. In multiple sclerosis patients fluoxetine administration may improve energy supply in neuron cells and thus inhibit axonal degeneration. In a preliminary pilot study, 15 patients with multiple sclerosis (MS) were examined by diffusion tensor imaging (DTI) and (1)H magnetic resonance spectroscopy (MRS) in order to quantify the brain tissue diffusion properties (fractional anisotropy, apparent diffusion coefficient) and metabolite levels (choline, creatine and N-acetylaspartate) in cortical gray matter brain tissue, in normal appearing white matter and in white matter lesions. After oral administration of fluoxetine (20 mg/day) for 1 week, the DTI and MRS measurements were repeated and after treatment with a higher dose (40 mg/day) during the next week, a third series of DTI/MRS examinations was performed in order to assess any changes in diffusion properties and metabolism. One trend was observed in gray matter tissue, a decrease of choline measured at weeks 1 and 2 (significant in a subgroup of 11 relapsing remitting/secondary progressive MS patients). In white matter lesions, the apparent diffusion coefficient was increased at week 1 and N-acetylaspartate was increased at week 2 (both significant). These preliminary results provide evidence of a neuroprotective effect of fluoxetine in MS by the observed partial normalization of the structure-related MRS parameter N-acetylaspartate in white matter lesions. PMID:19017554

Sijens, Paul E; Mostert, Jop P; Irwan, Roy; Potze, Jan Hendrik; Oudkerk, Matthijs; De Keyser, Jacques

2008-12-30

196

Proof of principle study of the use of a CMOS active pixel sensor for proton radiography  

SciTech Connect

Purpose: Proof of principle study of the use of a CMOS active pixel sensor (APS) in producing proton radiographic images using the proton beam at the Massachusetts General Hospital (MGH). Methods: A CMOS APS, previously tested for use in s-ray radiation therapy applications, was used for proton beam radiographic imaging at the MGH. Two different setups were used as a proof of principle that CMOS can be used as proton imaging device: (i) a pen with two metal screws to assess spatial resolution of the CMOS and (ii) a phantom with lung tissue, bone tissue, and water to assess tissue contrast of the CMOS. The sensor was then traversed by a double scattered monoenergetic proton beam at 117 MeV, and the energy deposition inside the detector was recorded to assess its energy response. Conventional x-ray images with similar setup at voltages of 70 kVp and proton images using commercial Gafchromic EBT 2 and Kodak X-Omat V films were also taken for comparison purposes. Results: Images were successfully acquired and compared to x-ray kVp and proton EBT2/X-Omat film images. The spatial resolution of the CMOS detector image is subjectively comparable to the EBT2 and Kodak X-Omat V film images obtained at the same object-detector distance. X-rays have apparent higher spatial resolution than the CMOS. However, further studies with different commercial films using proton beam irradiation demonstrate that the distance of the detector to the object is important to the amount of proton scatter contributing to the proton image. Proton images obtained with films at different distances from the source indicate that proton scatter significantly affects the CMOS image quality. Conclusion: Proton radiographic images were successfully acquired at MGH using a CMOS active pixel sensor detector. The CMOS demonstrated spatial resolution subjectively comparable to films at the same object-detector distance. Further work will be done in order to establish the spatial and energy resolution of the CMOS detector for protons. The development and use of CMOS in proton radiography could allow in vivo proton range checks, patient setup QA, and real-time tumor tracking.

Seco, Joao; Depauw, Nicolas [Francis H. Burr Proton Therapy Center, Department of Radiation Oncology, Massachusetts General Hospital (MGH), Boston, Massachusetts 02114 (United States)

2011-02-15

197

The Schwarzschild Proton  

SciTech Connect

We review our model of a proton that obeys the Schwarzschild condition. We find that only a very small percentage ({approx}10{sup -39}%) of the vacuum fluctuations available within a proton volume need be cohered and converted to mass-energy in order for the proton to meet the Schwarzschild condition. This proportion is equivalent to that between gravitation and the strong force where gravitation is thought to be {approx}10{sup -38} to 10{sup -40} weaker than the strong force. Gravitational attraction between two contiguous Schwarzschild protons can accommodate both nucleon and quark confinement. We calculate that two contiguous Schwarzschild protons would rotate at c and have a period of 10{sup -23} s and a frequency of 10{sup 22} Hz which is characteristic of the strong force interaction time and a close approximation of the gamma emission typically associated with nuclear decay. We include a scaling law and find that the Schwarzschild proton data point lies near the least squares trend line for organized matter. Using a semi-classical model, we find that a proton charge orbiting at a proton radius at c generates a good approximation to the measured anomalous magnetic moment.

Haramein, Nassim [Resonance Project Foundation, P.O. Box 764, Holualoa, HI 96725 (United States)

2010-11-24

198

Proton transport in polarizable water  

Microsoft Academic Search

Proton mobility in water determines the conductive properties of water-based proton conductors. We address the problem of proton mobility in pure water using a new, simple, Newtonian molecular dynamics water model which is applicable to proton-rich environments (e.g., polymer electrolyte membranes). This model has degrees of freedom that are ``inertial'' and ``inertialess'' relative to the proton. The solvated proton is

S. Walbran; A. A. Kornyshev

2001-01-01

199

MR imaging of osteochondral grafts and autologous chondrocyte implantation  

Microsoft Academic Search

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

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

2007-01-01

200

Evaluation of magnetic resonance imaging-compatible needles and interactive sequences for musculoskeletal interventions using an open high-field magnetic resonance imaging scanner.  

PubMed

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 degrees to 90 degrees ) 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 degrees to B0. Overall, the proton density-weighted spin-echo sequences had the best CNR (CNR(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. PMID:19705200

Wonneberger, Uta; Schnackenburg, Bernhard; Streitparth, Florian; Walter, Thula; Rump, Jens; Teichgräber, Ulf K M

2009-08-25

201

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

202

Proton radiography of inertial fusion implosions.  

PubMed

A distinctive way of quantitatively imaging inertial fusion implosions has resulted in the characterization of two different types of electromagnetic configurations and in the measurement of the temporal evolution of capsule size and areal density. Radiography with a pulsed, monoenergetic, isotropic proton source reveals field structures through deflection of proton trajectories, and areal densities are quantified through the energy lost by protons while traversing the plasma. The two field structures consist of (i) many radial filaments with complex striations and bifurcations, permeating the entire field of view, of magnetic field magnitude 60 tesla and (ii) a coherent, centrally directed electric field of order 10(9) volts per meter, seen in proximity to the capsule surface. Although the mechanism for generating these fields is unclear, their effect on implosion dynamics is potentially consequential. PMID:18309079

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

2008-02-29

203

The Proton launcher  

NASA Astrophysics Data System (ADS)

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

Bond, A.; Parfitt, J.

1985-08-01

204

Statistical Behavior of Proton and Electron Auroras During Substorms  

NASA Astrophysics Data System (ADS)

The IMAGE FUV imager can provide global maps of electron and proton precipitation and it is possible to observe how these maps change as a result of substorms. The large body of IMAGE FUV data permits the performance of a superimposed epoch analysis for many substorms. For each substorm the onset locations and times were determined from the Wideband Imaging Camera (WIC) images which represent mainly electron auroras. For the superimposed epoch analysis the WIC (electron) and Spectrographic Imager SI12 (proton) images were transformed into rectangular magnetic latitude (MLAT) and magnetic local time coordinates (MLT). Each event was plotted on a time scale related to the time of onset and the MLT scale was shifted until the onset point of each substorm was lined up at 0 relative magnetic local time (RMLT). A double Gaussian was then fitted to the data at RMLT of -4,-2,0,+2,+4 by representing the auroral intensity, I, as a function of MLAT. From the Gaussian coefficients we were able to obtain the mean of the peak auroral intensities, the mean location of the maximum intensity, and the mean position of the poleward and equatorward boundary of the proton and electron precipitation. From 91 substorms we derived some statistically meaningful quantities. We showed that pre-substorm there is an equatorward motion of the equatorward boundary of the electron and proton aurora. At onset the proton auroral peak intensity increases only by a factor of two compared to a factor of 5 for the electrons. There is rapid poleward expansion of the proton aurora after onset which slows down after the first few minutes. The electron onset continues towards higher latitudes. The relative position of the proton and electron aurora and their boundaries was investigated for various RMLT during substorm phases.

Morsony, B.; Mende, S.; Frey, H.; Immel, T.

2002-12-01

205

Apparatus for proton radiography  

DOEpatents

An apparatus for effecting diagnostic proton radiography of patients in hospitals comprises a source of negative hydrogen ions, a synchrotron for accelerating the negative hydrogen ions to a predetermined energy, a plurality of stations for stripping extraction of a radiography beam of protons, means for sweeping the extracted beam to cover a target, and means for measuring the residual range, residual energy, or percentage transmission of protons that pass through the target. The combination of information identifying the position of the beam with information about particles traversing the subject and the back absorber is performed with the aid of a computer to provide a proton radiograph of the subject. In an alternate embodiment of the invention, a back absorber comprises a plurality of scintillators which are coupled to detectors.

Martin, Ronald L. (La Grange, IL)

1976-01-01

206

Technology for proton therapy.  

PubMed

The technology that is used for the production and delivery of therapeutic proton beams is reviewed. Increased interest in this treatment modality has inspired a new generation of technology development and research into methods that will make proton treatment facilities more widely available (less expensive) and more efficient. Proton beam therapy has been in use for more than 40 years; it remains a treatment modality of interest because it provides a highly conformal dose distribution to a wide variety of disease sites and the potential for improving clinical outcomes. Recent advances in beam scanning technology may represent the ultimate in external beam radiotherapy dose conformality and treatment delivery efficiency. We describe how this new technology can be integrated into a proton therapy facility. PMID:19672145

Flanz, Jacob; Smith, Alfred

207

THEORY OF PROTON EMITTERS  

SciTech Connect

Modern theoretical methods used to interpret recent experimental data on ground-state proton emission near the proton drip line are reviewed. Most of them are stationary and are aimed to compute proton decay widths {Gamma}{sub p} only. Comparison is made between these approaches before being compared to experimental data. Our time-dependent approach based on the numerical solution of the time-dependent Schroedinger equation (TDSE) for initial quasi-stationary single-proton states is then introduced. It is shown that much deeper insights into the physics of this clean multidimensional quantum tunneling effect can be accessed, and that in addition to {Gamma}{sub p}, other physical quantities could be tested experimentally, offering new stringent tests on nuclear physics models away from the valley of {beta}-stability. Finally, the necessity of using the TDSE approach in more complex, dynamical, problems is demonstrated.

P. TALOU

2000-08-01

208

New inorganic proton conductors  

SciTech Connect

High values of proton conductivity have been observed in a class of hydrated metal oxide pyrochlores, HMO/sub 3/.xH/sub 2/O (M = Sb, Nb, Ta). Two new polymorphs of HSbO/sub 3/.xH/sub 2/O have been synthesized and are also found to be good proton conductors. One polymorph has a layer structure and is derived from KSbO/sub 3/ with the ilmenite structure. The other new HSbO/sub 3/.xH/sub 2/O polymorph has the cubic KSbO/sub 3/ structure. A correlation of TGA, IR, NMR, and proton conductivity data suggests that the best inorganic proton conductors (10-2-1 at 80/sup 0/C) are hydrates; this supports a Grotthus-type conduction mechanism analogous to that observed in aqueous media.

Chowdhry, U.; Barkley, J.R.; English, A.D.; Sleight, A.W.

1982-07-01

209

Proton Pump Inhibitors (PPIs)  

Center for Drug Evaluation (CDER)

... Some studies found that those at greatest risk for these fractures received high doses of proton pump inhibitors or used them for one year or more. ... More results from www.fda.gov/drugs/resourcesforyou/healthprofessionals

210

?? Production in Proton-Proton Collisions  

NASA Astrophysics Data System (ADS)

At CELSIUS-WASA the two-pion production in proton-proton collisisons has been measured exclusively from threshold up to the energy regime, where both of the collision partners are expected to be excited to the ? state. The measurements constitute the first kinematically complete data samples of solid statistics in this energy range. Most of the data have been obtained for the ?+?- and ?0?0channels. Whereas at near-threshold energies the differential distributions can be succesfully explained by chiral dynamics and Roper excitation, respectively, the data for the ?+?- channel in the ?? region can be described only, if the special configuration (??)0+ is assumed. The data for the ?0?0 channel moreover exhibit a low-mass enhancement in the ?0?0 invariant mass spectrum, which is reminiscent of the ABC-effect found in double-pionic fusion to light nuclei.

Skorodko, T.; Bashkanov, M.; Bogoslowsky, D.; Calén, H.; Cappellaro, F.; Clement, H.; Demiroers, L.; Ekström, C.; Fransson, K.; Greiff, J.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, T.; Kaskulov, M. M.; Keleta, S.; Khakimova, O.; Koch, I.; Kren, F.; Kullander, S.; Kup??, A.; Kuznetsov, A.; Marciniewski, P.; Meier, R.; Morosov, B.; Oelert, W.; Pauly, C.; Petukhov, Y.; Povtorejko, A.; Ruber, R. J. M. Y.; Schwick, A.; Scobel, W.; Shafigullin, R.; Shwartz, B.; Sopov, V.; Stepaniak, J.; Tchernyshev, V.; Thörngren-Engblom, P.; Tikhomirov, V.; Turowiecki, A.; Wagner, G. J.; Wolke, M.; Yamamoto, A.; Zabierowski, J.; Z?oman?zuk, J.

211

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

212

The Proton launcher  

Microsoft Academic Search

The capabilities, design features and missions for the Soviet Proton booster are described. The Proton, outfitted with six strap-on boosters, launched the Vega 1 and 2 Venus\\/Halley dual mission spacecraft. RD-253 engines burn N2O4 and UDMH fuels, possibly through a preburner before the combustion chamber. A vacuum thrust of 450,000 lb is projected for the engine. Analyses are presented to

A. Bond; J. Parfitt

1985-01-01

213

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

214

Proton Decay Theory  

Microsoft Academic Search

An update is given of the gauge coupling values. The status of the original SU(5) Georgi-Glashow model predictions, which assume a great desert between m\\/sub W\\/ and m\\/sub X\\/, the unification mass scale, is described. Gauge boson mediated proton decay in the SU(5) model, and proton decay via Higgs scalars are discussed. The inclusion of supersymmetry is grand unified theories

W. J. Marciano

1986-01-01

215

Proton transport by halorhodopsin  

SciTech Connect

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

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

1996-05-28

216

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

217

Proton conductivity: Materials and applications  

Microsoft Academic Search

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

Klaus-Dieter Kreuer

1996-01-01

218

Temporal evolution of proton precipitation associated with the plasmaspheric plume  

NASA Astrophysics Data System (ADS)

The temporal evolution of afternoon sector proton precipitation observed by a global auroral imager is examined in detail for two case events. We focus on precipitation regions that are magnetically mapped to the plasmapause and plasmaspheric plume regions. The spatial and temporal variation of the plume-associated precipitation, including its relationship to the main proton oval, is dependent on the prevailing solar wind and magnetospheric driving conditions. Two contrasting events are presented here in association with 1) a substorm injection and 2) a northward IMF turning. We find that proton precipitation within the plasmaspheric plume is a persistent feature during geomagnetically disturbed periods, but the precipitation regions only appear latitudinally detached from the main proton oval under specific conditions. The evolution in both time and space of the plume-associated precipitation regions is consistent with theoretical predictions for EMIC wave scattering of protons in the ring current energy range.

Spasojevic, M.; Fuselier, S. A.

2009-12-01

219

In Vivo Imaging of Macrophages during the Early-Stages of Abdominal Aortic Aneurysm Using High Resolution MRI in ApoE?/? Mice  

PubMed Central

Background Angiotensin II (ANG II) promotes vascular inflammation and induces abdominal aortic aneurysm (AAA) in hyperlipidemic apolipoprotein E knock-out (apoE?/?) mice. The aim of the present study was to detect macrophage activities in an ANG II-induced early-stage AAA model using superparamagnetic iron oxide (SPIO) as a marker. Methodology/Principal Findings Twenty-six male apoE?/? mice received saline or ANG II (1000 or 500 ng/kg/min) infusion for 14 days. All animals underwent MRI scanning following administration of SPIO with the exception of three mice in the 1000 ng ANG II group, which were scanned without SPIO administration. MR imaging was performed using black-blood T2 to proton density -weighted multi-spin multi-echo sequence. In vivo MRI measurement of SPIO uptake and abdominal aortic diameter were obtained. Prussian blue, CD68,?-SMC and MAC3 immunohistological stains were used for the detection of SPIO, macrophages and smooth muscle cells. ANG II infusion with 1000 ng/kg/min induced AAA in all of the apoE?/? mice. ANG II infusion exhibited significantly higher degrees of SPIO uptake, which was detected using MRI as a distinct loss of signal intensity. The contrast-to-noise ratio value decreased in proportion to an increase in the number of iron-laden macrophages in the aneurysm. The aneurysmal vessel wall in both groups of ANG II treated mice contained more iron-positive macrophages than saline-treated mice. However, the presence of cells capable of phagocytosing haemosiderin in mural thrombi also induced low-signal-intensities via MRI imaging. Conclusions/Significance SPIO is taken up by macrophages in the shoulder and the outer layer of AAA. This alters the MRI signaling properties and can be used in imaging inflammation associated with AAA. It is important to compare images of the aorta before and after SPIO injection.

Yao, Yuyu; Wang, Yuanyuan; Zhang, Yi; Li, Yefei; Sheng, Zulong; Wen, Song; Ma, Genshan; Liu, Naifeng; Fang, Fang; Teng, Gao-Jun

2012-01-01

220

Magnifying lens for 800 MeV proton radiography.  

PubMed

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. PMID:22047305

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

2011-10-01

221

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

222

Proton re-evaluated  

NASA Astrophysics Data System (ADS)

The three versions of the Proton booster used to date are presented and connections are made between the Proton and the U.S.S.R.'s lunar program. The question as to whether or not the proton could be manrated is addressed. The original version of the Proton, known as the SL-9 vehicle, consists of the first stage cluster of six engines with a 13-ton second stage. The second version was the SL-12 and the third version was the SL-13. The SL-13 consists of the SL-9 with a new 5.6-ton third stage added. The SL-12, introduced before the SL-13, uses the basic three stages of the SL-13 with a fourth escape stage added. The use of the SL-12 vehicle in two major series of applications satellites put in earth orbit is described. It is noted that if the loss of the Challenger Orbiter results in a major shift in Shuttle payload philosophy, the Proton and other expendable boosters will be called upon to fill the gaps.

Clark, P. S.

1986-08-01

223

Pediatric Focused Safety Review Proton Pump Inhibitors  

Center for Biologics Evaluation and Research (CBER)

Text Version... Proton Pump Inhibitors ... Therapeutic Category: Proton Pump Inhibitor Therapeutic Category: Proton Pump Inhibitor (PPI) ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

224

Statistical behavior of proton and electron auroras during substorms  

NASA Astrophysics Data System (ADS)

The substorm evolution was studied by performing a superposed epoch analysis of 91 substorms using IMAGE FUV data. Onset locations and times were determined from images produced by the Wideband Imaging Camera (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) and magnetic local time (MLT) coordinates and plotted on a timescale related to the time of substorm onset (T = 0) and to a Relative MLT (RMLT) normalized to onset MLT. A double Gaussian was fitted to the auroral intensity data as a function of ML at RMLT of -4, -2, 0, +2, and +4. From the Gaussian coefficients the means of several parameters were plotted as a function of time. Presubstorm, there was an equatorward motion of the mean low-latitude boundary of the electron and proton aurora. There was no evidence of preonset auroral fading in the mean intensity. At onset the proton auroral peak intensity increased only by a factor of 2 compared with ˜5 for the electrons. At RMLT = 0, rapid poleward expansion of the proton aurora after onset occurred. The proton expansion slowed down after the first few minutes, while the electron surge continued toward higher latitudes. The mean poleward expansion of the electron aurora reached about 3.5° in 5 min and reached a total expansion of 5.5° in an hour. The protons expanded about 2.5° in 5 min and expanded about 3° one hour after onset. The latitude width of the aurora increased at onset due to both a large poleward and a moderate equatorward expansion. There appeared to be stronger substorm-related activity in the local time range toward dawn than toward dusk. In the RMLT sector duskward of onset the proton auroras were located equatorward of the electrons and poleward in the dawnward RMLT sector.

Mende, S. B.; Frey, H. U.; Morsony, B. J.; Immel, T. J.

2003-09-01

225

Physics controversies in proton therapy.  

PubMed

The physical characteristics of proton beams are appealing for cancer therapy. The rapid increase in operational and planned proton therapy facilities may suggest that this technology is a "plug-and-play" valuable addition to the arsenal of the radiation oncologist and medical physicist. In reality, the technology is still evolving, so planning and delivery of proton therapy in patients face many practical challenges. This review article discusses the current status of proton therapy treatment planning and delivery techniques, indicates current limitations in dealing with range uncertainties, and proposes possible developments for proton therapy and supplementary technology to try to realize the actual potential of proton therapy. PMID:23473685

Engelsman, Martijn; Schwarz, Marco; Dong, Lei

2013-04-01

226

Synchrotron radiation from protons  

SciTech Connect

Synchrotron radiation from protons, though described by the same equations as the radiation from electrons, exhibits a number of interesting features on account of the parameters reached in praxis. In this presentation, we shall point out some of the features relating to (i) normal synchrotron radiation from dipoles in proton machines such as the High Energy Booster and the Superconducting Super Collider; (ii) synchrotron radiation from short dipoles, and its application to light monitors for proton machines, and (iii) synchrotron radiation from undulators in the limit when, the deflection parameter is much smaller than unity. The material for this presentation is taken largely from the work of Hofmann, Coisson, Bossart, and their collaborators, and from a paper by Kim. We shall emphasize the qualitative aspects of synchrotron radiation in the cases mentioned above, making, when possible, simple arguments for estimating the spectral and angular properties of the radiation. Detailed analyses can be found in the literature.

Dutt, S.K.

1992-12-01

227

Shielding of relativistic protons.  

PubMed

Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick (about 20 g/cm2) blocks of lucite (PMMA) or aluminium (Al). We found that the dose rate was increased 40-60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General-Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation field after the shield has been characterized for its biological effectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.5-3 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (<10 keV/microm), which explains the approximately unitary value measured for the relative biological effectiveness. PMID:17256178

Bertucci, A; Durante, M; Gialanella, G; Grossi, G; Manti, L; Pugliese, M; Scampoli, P; Mancusi, D; Sihver, L; Rusek, A

2007-01-26

228

?-delayed proton decays near the proton drip line  

NASA Astrophysics Data System (ADS)

In order to improve the measuring efficiency, a ``proton-gamma'' coincidence technique in combination with a He-jet tape transport system was proposed and employed to identify the ?-delayed proton precursors. The study of ?-delayed proton decays near the proton drip line by using the ``proton-gamma'' coincidence technique over the last 5 years at the Institute of Modern Physics, Lanzhou, China, was summarized. New ?-delayed proton precursors 121Ce, 125Nd, 128Pm, 129Sm, 135Gd, 137Gd, 139Dy, 142Ho, and 149Yb in the rare-earth region along a speculated proton drip line were synthesized and identified for the first time. The ?-delayed proton decays of 81Zr, 85Mo, 89Ru, and 93Pd in Tz=1/2 series as well as 92Rh in Tz=1 series were observed. .

Xu, S.-W.; Li, Z.-K.; Xie, Y.-X.; Huang, W.-X.; Ma, R.-C.; Pan, Q.-Y.; Wang, X.-D.; Yu, Y.

2002-04-01

229

Localized dayside proton aurora at high latitudes  

NASA Astrophysics Data System (ADS)

Two types of dayside localized proton-induced auroral emissions on the dayside were identified in SI12 images from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. "Auroral oval spots" occurred at or toward the poleward edge of the dayside proton auroral oval. "Polar cap spots" occurred well into the polar cap. The polar cap spots occurred when the interplanetary magnetic field (IMF) was strongly northward and radially aligned along the Sun-Earth line, which results in reconnection with northern lobe field lines. For the auroral oval spots that occurred during northward-IMF only, there was a large azimuthal component of the IMF. During northward IMF conditions, a large azimuthal component of the IMF leads to reconnection at high latitudes on closed geomagnetic field lines. The reconnection site would map closer to auroral oval latitudes, which is consistent with the location of the auroral oval spots. The auroral oval spots were found to be much larger in size and total intensity than the polar cap spots, but the average intensities of the two types of spots were comparable. The average intensity of the auroral oval spots was proportional to the solar wind dynamic pressure and solar wind density, suggesting that the average intensity of the auroral oval spots is dependent on the number of protons precipitating from the reconnection site, rather than the proton energy. No clear trend was found for the polar cap spots, but there was a notable lack of polar cap spots for high solar wind dynamic pressures and densities.

Bryant, C. R.; McWilliams, K. A.; Frey, H. U.

2013-06-01

230

Predictions of diffractive cross sections in proton-proton collisions  

NASA Astrophysics Data System (ADS)

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

Goulianos, Konstantin

2013-04-01

231

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

Microsoft Academic Search

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

William Daughton; S. Peter Gary; Dan Winske

1999-01-01

232

New Proton Radioactivities and Spectroscopy Using Proton Decay Tagging  

Microsoft Academic Search

Groundstate proton radioactivity only occurs when the proton dripline has been crossed. The study of proton decay spectroscopy has steadily evolved, starting as a tool for delineating the dripline, then as method for accurate mass determinations, then as a method for determining the nuclear wavefunctions, through measuring decay rates. Most recently, the studies have explored the shape of emitters and

D. Seweryniak

2001-01-01

233

Nuclear spin noise imaging  

PubMed Central

NMR images were obtained from the proton spin noise signals of a water-containing phantom, which was placed in the highly tuned, low-noise resonant circuit of a cryogenically cooled NMR probe in the presence of systematically varied magnetic field gradients. The spatially resolved proton spin density was obtained from the raw signal by a modified projection–reconstruction protocol. Although spin noise imaging is inherently less sensitive than conventional magnetic resonance imaging, it affords an entirely noninvasive visualization of the interior of opaque objects or subjects. Thus, tomography becomes possible even when neither x-ray nor radio frequency radiation can be applied for technical or safety reasons.

Muller, Norbert; Jerschow, Alexej

2006-01-01

234

Cusp Proton Aurora: A Possible Mechanism  

NASA Astrophysics Data System (ADS)

On April 21, 2001 an interplanetary CME started to interact with the magnetosphere when CLUSTER spacecraft were travelling in the cusp region. This interaction produced a strong magnetic storm (Dst=-103 nT) in the Earth. The thrust of this paper concentrates the cusp proton aurora which was caused by the hitting of the leading phase of the CME. This paper demonstrates that cusp proton aurora observed by IMAGE satellites can not only appear during IMF northward as described by many researchers, also could be triggered during the southward IMF when the reverse convection has been generated by the Y component dominated IMF. The location of the cusp proton aurora has been shifted about 30 degrees from dawnside to duskside when IMF By changed from -10 nT to 5 nT. Proton cusp aurora requirement seems to bea reverse convection in the cusp region (not only IMF northward, IMF By is also an important parameter!) and high density solar wind plasma instead of the northward IMF.

Zong, Q.-G.; Fritz, T. A.; Spence, H.; Frey, H. U.; Korth, A.; Daly, P. W.; Dunlop, M.

2003-04-01

235

The Search for Proton Decay.  

ERIC Educational Resources Information Center

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

Marshak, Marvin L.

1984-01-01

236

Search for Proton Decay: Introduction.  

National Technical Information Service (NTIS)

In interpreting contained events observed in various proton decay detectors one can sometimes postulate, though usually not unambiguously, a potential decay mode of the proton, called a candidate. It is called a candidate, because for any individual event...

M. Goldhaber

1984-01-01

237

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

238

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

239

Proton beam therapy  

Microsoft Academic Search

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

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

2005-01-01

240

Medical proton accelerator facility.  

PubMed

This paper presents a specialized medical accelerator facility designed for proton radiation therapy and for production of short-lived nuclide-labelled radiopharmaceuticals. General features of the facility structure, the choice of principles of beam delivery, physical and technical problems connected with clinical work, and biomedical research are discussed. PMID:2846478

Khoroshkov, V S; Goldin, L L

1988-10-01

241

Planning for proton therapy.  

PubMed

Bruce Johnson, senior vice-president at the Houston, Texas offices of internationally-recognised HKS Architects, examines the considerable physical challenge of accommodating sizeable proton external beam radiation therapy equipment into hospitals, drawing on work undertaken by the practice to date in designing hospitals to cater for such sizeable machinery. PMID:20839523

Johnson, Bruce

2010-08-01

242

Proton dosimetry intercomparison  

Microsoft Academic Search

Background and purpose: Methods for determining absorbed dose in clinical proton beams are based on dosimetry protocols provided by the AAPM and the ECHED. Both groups recommend the use of air-filled ionization chambers calibrated in terms of exposure or air kerma in a 60Co beam when a calorimeter or Faraday cup dosimeter is not available. The set of input data

S. Vatnitsky; J. Siebers; D. Miller; M. Moyers; M. Schaefer; D. Jones; S. Vynckier; Y. Hayakawa; S. Delacroix; U. Isacsson; J. Medin; A. Kacperek; A. Lomax; A. Coray; H. Kluge; J. Heese; L. Verhey; I. Daftari; K. Gall; G. Lam; T. Beck; G. Hartmann

1996-01-01

243

Proton Bunching Options  

SciTech Connect

Muon Colliders need intense, very short, proton bunches. The requirements are presented and a number of possible bunching systems discussed. The best solution uses a small super-conducting buncher ring with 6 bunches that are taken though separate transports and combined on the target.

Palmer, R.B.

2009-10-19

244

Search for proton decay  

SciTech Connect

Following a very brief description of the theoretical developments which motivated the search for proton decay, I shall describe one of these experiments (the IMB experiment) in some detail. Then I shall compare recent results from that experiment with those from other detectors.

Bionta, R.; Blewitt, G.; Bratton, C.B.; Casper, D.; Cortez, B.G.; Errede, S.; Foster, G.W.; Gajewski, W.; Ganezer, K.S.; Goldhaber, M.

1984-11-15

245

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

PubMed

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

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

2012-12-26

246

Proton vs neutron halo breakup  

Microsoft Academic Search

In this paper we show how effective parameters such as effective binding energies can be defined for a proton in the combined nuclear-Coulomb potential, including also the target potential, in the case in which the proton is bound in a nucleus which is partner of a nuclear reaction. Using such effective parameters the proton behaves similar to a neutron. In

Angela Bonaccorso; David M. Brink; Carlos A. Bertulani

2004-01-01

247

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

248

Proton computed tomography from multiple physics processes.  

PubMed

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. PMID:24076769

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

2013-09-27

249

New concept of a range verification system for proton therapy using a photon counting detector  

NASA Astrophysics Data System (ADS)

A range verification method plays an important role in the quality assurance of the proton therapy offering the high conformity and reduction in radiation dose. To localize the distal falloff of the dose distribution, secondary particles (C-11, O-15, and N-13) produced by the proton interaction within the patient body can be used as a measure of the beam range. We proposed a multi-modality imaging system for X-ray and gamma-ray coincidence imaging using CdZnTe detectors to measure proton range verification. The detector system consists of two parallel planes of detectors and an X-ray generator. An X-ray image is acquired using one detector for the verification of 2-dimensional anatomical structure of the patient, and the paired gamma rays from the annihilation are imaged with two modules to determine the maximum range of proton penetration. Image registration is intrinsic because the X-ray and gamma ray images are acquired in the same geometry. 110 and 140 MeV proton beam, a cylindrical tissue phantom, and two rectangular CdZnTe detectors were modeled, and the imaging performance of this system was evaluated using GATE simulation. The results showed the potential benefits of an X-ray/gamma-ray imaging with photon counting detectors for range verification in proton therapy.

Kim, Jin Sung; An, Su Jung; Chung, Yong Hyun

2012-06-01

250

Antideuteron production in proton-proton and proton-nucleus collisions  

NASA Astrophysics Data System (ADS)

The experimental data of the antideuteron production in proton-proton and proton-nucleus collisions are analyzed within a simple model based on the diagrammatic approach to the coalescence model. This model is shown to be able to reproduce most of existing data without any additional parameter.

Duperray, R. P.; Protasov, K. V.; Voronin, A. Yu.

2003-01-01

251

NMR imaging  

SciTech Connect

Since hydrogen is the most abundant element in all living organisms, proton NMR lends itself well as a method of investigation in biology and medicine. NMR imaging has some special advantages as a diagnostic tool: no ionizing radiation is used, it is noninvasive; it provides a safer means of imaging than the use of x-rays, gamma rays, positrons, or heavy ions. In contrast with ultrasound, the radiation penetrates the bony structures without attenuation. In additional to morphological information, NMR imaging provides additional diagnostic insights through relaxation parameters, which are not available from other imaging methods. In the decade since the first primitive NMR images were obtained, the quality of images now obtained approaches those from CT x-ray scanners. Prototype instruments are being constructed for clinical evaluation and the first whole-body scanners are beginning to appear on the market at costs comparable to CT scanners. Primary differences in equipment for conventional NMR and NMR imaging are the much larger aperture magnets that are required for the examination of human subjects and the addition of coils to generate field gradients and facilities for manipulating the gradients. Early results from clinical trials in many parts of the world are encouraging, and in a few years, the usefuleness of this modality of medical imaging to the medical profession in diagnosis and treatment of disease will be defined. 10 figures.

Andrew, E.R.

1983-04-01

252

Proton transfer events in GFP.  

PubMed

Proton transfer is one of the most important elementary processes in biology. Green fluorescent protein (GFP) serves as an important model system to elucidate the mechanistic details of this reaction, because in GFP proton transfer can be induced by light absorption. Illumination initiates proton transfer through a 'proton-wire', formed by the chromophore (the proton donor), water molecule W22, Ser205 and Glu222 (the acceptor), on a picosecond time scale. To obtain a more refined view of this process, we have used a combined approach of time resolved mid-infrared spectroscopy and visible pump-dump-probe spectroscopy to resolve with atomic resolution how and how fast protons move through this wire. Our results indicate that absorption of light by GFP induces in 3 ps (10 ps in D(2)O) a shift of the equilibrium positions of all protons in the H-bonded network, leading to a partial protonation of Glu222 and to a so-called low barrier hydrogen bond (LBHB) for the chromophore's proton, giving rise to dual emission at 475 and 508 nm. This state is followed by a repositioning of the protons on the wire in 10 ps (80 ps in D(2)O), ultimately forming the fully deprotonated chromophore and protonated Glu222. PMID:21847481

Di Donato, Mariangela; van Wilderen, Luuk J G W; Van Stokkum, Ivo H M; Stuart, Thomas Cohen; Kennis, John T M; Hellingwerf, Klaas J; van Grondelle, Rienk; Groot, Marie Louise

2011-08-17

253

Proton magnetic resonance spectroscopy of systemic lupus erythematosus involving the central nervous system  

Microsoft Academic Search

We examined 13 patients with neurological manifestations of systemic lupus erythematosus (SLE) based on previous and\\/or current neurological or psychotic episodes by magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) together with psychiatric and cognitive assessment. MRI was abnormal in 7 patients, showing high signal lesions in the white matter and\\/or cerebral atrophy. Proton MRS centred on white

C. A. Davie; A. Feinstein; L. D. Kartsounis; G. J. Barker; N. J. McHugh; M. J. Walport; M. A. Ron; I. F. Moseley; W. I. McDonald; D. H. Miller

1995-01-01

254

Smashing Protons to Smithereens  

ScienceCinema

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

255

Proton-Conducting Oxides  

NASA Astrophysics Data System (ADS)

The structural and chemical parameters determining the formation and mobility of protonic defects in oxides are discussed, and the paramount role of high-molar volume, coordination numbers, and symmetry are emphasized. Symmetry also relates to the structural and chemical matching of the acceptor dopant. Y-doped BaZrO3-based oxides are demonstrated to combine high stability with high proton conductivity that exceeds the conductivity of the best oxide ion conductors at temperatures below about 700oC. The unfavorably high grain boundary impedances and brittleness of ceramics have been reduced by forming solid solutions with small amounts of BaCeO3, and an initial fuel cell test has demonstrated that proton-conducting electrolytes based on Y-doped BaZrO3 provide alternatives for separator materials in solid oxide fuel cells (SOFCs). These materials have the potential to operate at lower temperatures compared with those of conventional SOFCs, and the appearance of chemical water diffusion across the electrolyte at typical operation temperatures (T = 500-800oC) allows the use of dry methane as a fuel.

Kreuer, K. D.

2003-08-01

256

Statistics of the longitudinal splitting of proton aurora during substorms  

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

257

Proton transport in polarizable water  

NASA Astrophysics Data System (ADS)

Proton mobility in water determines the conductive properties of water-based proton conductors. We address the problem of proton mobility in pure water using a new, simple, Newtonian molecular dynamics water model which is applicable to proton-rich environments (e.g., polymer electrolyte membranes). This model has degrees of freedom that are ``inertial'' and ``inertialess'' relative to the proton. The solvated proton is treated using a local empirical valence bond Hamiltonian, which allows for the efficient simulation of full charge, energy-conserving dynamics in single and multiple-proton systems. The solvated proton displays the Grotthus-type proton transfer mechanism, giving significantly enhanced transport in comparison with the classical diffusion of an H3O+ ion. The model yields an activation energy of 0.11 eV, in excellent agreement with experiment. The results are consistent with the observation that nonpolarizable water models, conditioned to reproduce correct values of the static dielectric constant, are predestined to give too large activation energies of proton mobility due to the overweighted spectrum of the slower nuclear modes.

Walbran, S.; Kornyshev, A. A.

2001-06-01

258

PROTON AND ANTI-PROTON DISTRIBUTIONS AT RHIC.  

SciTech Connect

Properties of transverse momentum spectra and rapidity dependence of protons and anti-protons in Au-Au collisions at {radical}(s{sub NN}) = 200 GeV are discussed. The net-proton yields are approximately constant at |y| < 1 and increases towards y {approx} 3. The mean rapidity loss is estimated to be in the range of 1.9 < {delta}y < 2.4.

VIDEBAEK,F.FOR THE BRAHMS COLLABORATION

2003-02-08

259

Amplitude structure in proton-proton elastic scattering  

Microsoft Academic Search

A comprehensive study of forward elastic proton-proton scattering over a wide energy range 10 <= s <= 3000 GeV2, is carried out in terms of s-channel helicity amplitudes. A hybrid model is constructed in which the pomeron exchange is represented by the sum of Bessel functions parameterizing the proton core and periphery; this is augmented by the exchange of Regge

E. Gotsman; U. Maor

1975-01-01

260

Measurement Of Gas Bubbles In Mercury Using Proton Radiography  

Microsoft Academic Search

An experiment using proton radiography on a small mercury loop for testing gas bubble injection was conducted at the Los Alamos Neutron Science Center (LANSCE) in December 2006. Small gas bubble injection is one of the approaches under development to reduce cavitation damage in the U.S. Spallation Neutron Source mercury target vessel. Several hundred radiograph images were obtained as the

Bernie Riemer; Philip R Bingham; Fesseha G Mariam; Frank E Merrill

2007-01-01

261

Proton Radiography Experiment to Visualize Gas Bubbles in Mercury  

Microsoft Academic Search

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

Bernie Riemer; David K Felde; Mark W Wendel; Fesseha G Mariam; Frank E Merrill

2007-01-01

262

Proton Radiography Experiments on Shocked High Explosive Products  

Microsoft Academic Search

We studied the propagation of detonation waves and reflections of normal incident detonation waves in explosive products using the 800 MeV proton radiography facility at LANSCE. Using this system, we obtain seven to twenty-one radiographic images of each experiment. We have examined the experimental wave velocity and density of the materials ahead and behind of the shocks as inferred from

Eric N. Ferm; Steve Dennison; Robert Lopez; Kathy Prestridge; John P. Quintana; Camilo Espinoza; Gary Hogan; Nick King; Julian D. Lopez; Frank Merrill; Kevin Morley; Christopher L. Morris; Peter Pazuchanics; Andy Saunders; Stuart A. Baker; Rodger Liljestrand; Richard T. Thompson

2004-01-01

263

Proton Synchrotron Radiation Diagnostics at HERA  

SciTech Connect

At HERA a proton synchrotron radiation beam emittance monitor has been installed which utilizes the radiation produced in the fringe field of a vertical deflecting dipole magnet. The beam spot is imaged onto the chip of a standard CCD camera by means of a concave mirror. An interference filter together with a polarization filter serve for resolution improvements. While the monitor was used for the first time in standard operational mode during the previous HERA run period, the set-up was improved in the last shut-down. With start of the new run period the monitor is in a stage of re-commissioning and the first results are presented.

Kube, G.; Priebe, G.; Wiebers, Ch.; Wittenburg, K. [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany)

2006-11-20

264

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

PubMed

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

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

2013-10-08

265

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

266

Proton MRS in neurological disorders.  

PubMed

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

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

1999-05-01

267

Proton structure functions at HERA  

Microsoft Academic Search

The electron-proton collider HERA, like an electron-mycroscope, explores the structure of the proton down to 10-16 cm and up to the situation of very high parton densities. The proton energy was upgraded from 820 to 920 GeV in the Fall of '98 and the luminosity has also substantially improved, with another factor of 3 upgrade expected to follow this year.

2001-01-01

268

Proton vs neutron halo breakup  

Microsoft Academic Search

In this paper we show how effective parameters such as effective binding\\u000aenergies can be defined for a proton in the combined nuclear-Coulomb potential,\\u000aincluding also the target potential, in the case in which the proton is bound\\u000ain a nucleus which is partner of a nuclear reaction. Using such effective\\u000aparameters the proton behaves similarly to a neutron. In

Angela Bonaccorso; David M. Brink; Carlos A. Bertulani

2004-01-01

269

Fractionated proton beam irradiation of pituitary adenomas  

SciTech Connect

Purpose: Various radiation techniques and modalities have been used to treat pituitary adenomas. This report details our experience with proton treatment of these tumors. Methods and Materials: Forty-seven patients with pituitary adenomas treated with protons, who had at least 6 months of follow-up, were included in this analysis. Forty-two patients underwent a prior surgical resection; 5 were treated with primary radiation. Approximately half the tumors were functional. The median dose was 54 cobalt-gray equivalent. Results: Tumor stabilization occurred in all 41 patients available for follow-up imaging; 10 patients had no residual tumor, and 3 had greater than 50% reduction in tumor size. Seventeen patients with functional adenomas had normalized or decreased hormone levels; progression occurred in 3 patients. Six patients have died; 2 deaths were attributed to functional progression. Complications included temporal lobe necrosis in 1 patient, new significant visual deficits in 3 patients, and incident hypopituitarism in 11 patients. Conclusion: Fractionated conformal proton-beam irradiation achieved effective radiologic, endocrinological, and symptomatic control of pituitary adenomas. Significant morbidity was uncommon, with the exception of postradiation hypopituitarism, which we attribute in part to concomitant risk factors for hypopituitarism present in our patient population.

Ronson, Brian B. [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA (United States); Schulte, Reinhard W. [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA (United States); Han, Khanh P. [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA (United States); Loredo, Lilia N. [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA (United States); Slater, James M. [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA (United States); Slater, Jerry D. [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, CA (United States)]. E-mail: jdslater@dominion.llumc.edu

2006-02-01

270

Proton irradiation and endometriosis.  

PubMed

Female rhesus monkeys given single total-body exposures of protons of varying energies developed endometriosis at a frequency significantly higher than that of nonirradiated animals of the same age. The minimum latency period was 7 years after exposure. The doses and energies of the radiation received were within the range that could be received by an aircrew member in near-earth orbit during a random solar flare event, leading to the conclusion that endometriosis should be a consideration in assessing the risk of delayed radiation effects in female crewmembers. PMID:6312953

Wood, D H; Yochmowitz, M G; Salmon, Y L; Eason, R L; Boster, R A

1983-08-01

271

Proton Size Anomaly  

SciTech Connect

A measurement of the Lamb shift in muonic hydrogen yields a charge radius of the proton that is smaller than the CODATA value by about 5 standard deviations. We explore the possibility that new scalar, pseudoscalar, vector, and tensor flavor-conserving nonuniversal interactions may be responsible for the discrepancy. We consider exotic particles that, among leptons, couple preferentially to muons and mediate an attractive nucleon-muon interaction. We find that the many constraints from low energy data disfavor new spin-0, spin-1, and spin-2 particles as an explanation.

Barger, Vernon [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Chiang, Cheng-Wei [Department of Physics and Center for Mathematics and Theoretical Physics, National Central University, Chungli, Taiwan 32001 (China); Institute of Physics, Academia Sinica, Nankang, Taipei 11925 (China); Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Keung, Wai-Yee [Department of Physics, University of Illinois, Chicago, Illinois 60607 (United States); Marfatia, Danny [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States); Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2011-04-15

272

Proton beam therapy  

PubMed Central

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

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

2005-01-01

273

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

274

Optical Diagnostics of Mercury Jet for an Intense Proton Target  

SciTech Connect

An optical diagnostic system is designed and constructed for imaging a free mercury jet interacting with a high intensity proton beam in a pulsed high-field solenoid magnet. The optical imaging system employs a back-illuminated, laser shadow photography technique. Object illumination and image capture are transmitted through radiation-hard multi-mode optical fibers and flexible coherent imaging fibers. A retro-reflected 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 level of the magnetic induction field is reported in this paper.

Park, H [Brookhaven National Laboratory (BNL); Tsang, T [Brookhaven National Laboratory (BNL); Kirk, H. [Brookhaven National Laboratory (BNL); Ladeinde, F [Stony Brook University (SUNY); Graves, Van B [ORNL; Spampinato, Philip Thomas [ORNL; Carroll, Adam J [ORNL; Titus, P [Massachusetts Institute of Technology (MIT); Mcdonald, K [Princeton University

2008-01-01

275

Optical diagnostics of mercury jet for an intense proton target  

SciTech Connect

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

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

2008-04-15

276

Optical diagnostics of mercury jet for an intense proton target.  

PubMed

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. PMID:18447556

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

277

Hard x-ray spectroscopy for proton flare prediction  

NASA Astrophysics Data System (ADS)

High energy interplanetary proton events can jeopardize vital military and civilian spacecraft by disrupting logical circuits and by actually damaging spacecraft electronic components. Studies of solar hard x-rays indicate that high-energy proton events observed near Earth are highly associated with an uncommon type of solar flare exhibiting temporal progressively hardening hard x-ray spectra. A hard x-ray spectrometer is being developed by the Czech Astronomical Institute to provide a test bed for evaluating this phenomenon as a possible proton-storm prediction method. The instrument is designed to measure hard x-ray spectra in a high fluence, high-energy particle background environment such as that found at geosynchronous altitude. This experiment has been selected for space flight by the DoD Space Test Program and will fly aboard the Department of Energy satellite, Multi-spectral thermal Imager, scheduled for a three year mission, beginning in late 1999. The timing of this mission, fortuitously, coincides with the experiment are: 1) to evaluate the efficacy of this type of solar instrument in predicting interplanetary proton storms; 2) to study the high-energy physics of solar flares in concert with the premier flight of the NOAA soft x-ray imaging telescope, SXI, on the GOES 12 weather satellite and other solar mission. If the first goal is demonstrated by this mission, continuous monitoring of the Sun for proton events could become operational from geo-synchronous orbit during solar cycle 24.

Garcia, Howard A.; Farnik, Frantisek; Kiplinger, Alan L.

1998-11-01

278

Proton treatment room concepts for precision and efficiency.  

PubMed

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

Schulte, Reinhard W

2007-08-01

279

Proton-electron elastic scattering and the proton charge radius  

NASA Astrophysics Data System (ADS)

It is suggested that proton elastic scattering on atomic electrons allows a precise measurement of the proton charge radius. The main advantage is that inverse kinematics allows one to access with a huge cross section very small values of transferred momenta, up to four orders of magnitude smaller than the ones presently achieved.

Gakh, G. I.; Dbeyssi, A.; Tomasi-Gustafsson, E.; Marchand, D.; Bytev, V. V.

2013-09-01

280

Low-Energy Proton Production by 160Mev Protons  

Microsoft Academic Search

Energy and angular distributions of emitted protons in the energy range 5 to 23 Mev from lead, tantalum, tin, and zinc when bombarded by 160-Mev protons were obtained. A peak was obtained in each of the energy distributions slightly below the Coulomb barrier of each element. The magnitude of the peaks increased with a decrease in the Coulomb barrier of

Raymond Fox; Norman F. Ramsey

1962-01-01

281

New Proton Radioactivities and Spectroscopy Using Proton Decay Tagging.  

NASA Astrophysics Data System (ADS)

Groundstate proton radioactivity only occurs when the proton dripline has been crossed. The study of proton decay spectroscopy has steadily evolved, starting as a tool for delineating the dripline, then as method for accurate mass determinations, then as a method for determining the nuclear wavefunctions, through measuring decay rates. Most recently, the studies have explored the shape of emitters and extracted information on the parent wavefunctions. Improvements in technique have allowed more sensitive measurements to be made, leading to the discovery of new isotopes even further from stability, and more complex decay patterns, both from groundstates and from isomers. Several new odd-odd emitters have been found. In iridium nuclei, four different isotopes beyond the dripline have been found to be proton emitters. Proton decays have also been extensively used to tag "in-beam" gamma-ray spectroscopic measurements, further clarifying the structure of these marginally bound systems. The state of proton decay spectroscopy will be reviewed, concentrating on the most recently discovered emitters and on proton decay tagging. The prospects for reaching further from stability and finding short-lived proton emitters in new mass regions will be reviewed. This work was supported by the US Department of Energy, Nuclear Physics Division, under contract W31-109-ENG38.

Seweryniak, D.

2001-10-01

282

Proton in SRF Niobium  

NASA Astrophysics Data System (ADS)

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

2011-03-01

283

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

284

Decoupling of photo- and proton cycle in the Asp85-->Glu mutant of bacteriorhodopsin.  

PubMed Central

Surface bound pH indicators were applied to study the proton transfer reactions in the mutant Asp85-->Glu of bacteriorhodopsin in the native membrane. The amino acid replacement induces a drastic acceleration of the overall rise of the M intermediate. Instead of following this acceleration, proton ejection to the extracellular membrane surface is not only two orders of magnitude slower than M formation, it is also delayed as compared with the wild-type. This demonstrates that Asp85 not only accepts the proton released by the Schiff's base but also regulates very efficiently proton transfer within the proton release chain. Furthermore, Asp85 might be the primary but is not the only proton acceptor/donor group in the release pathway. The Asp85-->Glu substitution also affects the proton reuptake reaction at the cytoplasmic side, although Asp85 is located in the proton release pathway. Proton uptake is slower in the mutant than in the wild-type and occurs during the lifetime of the O intermediate. This demonstrates a feed-back mechanism between Asp85 and the proton uptake pathway in bacteriorhodopsin. Images

Heberle, J; Oesterhelt, D; Dencher, N A

1993-01-01

285

Solar Proton Fluxes Since 1956.  

National Technical Information Service (NTIS)

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

R. C. Reedy

1977-01-01

286

Fragmentation pathways of protonated peptides.  

PubMed

The fragmentation pathways of protonated peptides are reviewed in the present paper paying special attention to classification of the known fragmentation channels into a simple hierarchy defined according to the chemistry involved. It is shown that the 'mobile proton' model of peptide fragmentation can be used to understand the MS/MS spectra of protonated peptides only in a qualitative manner rationalizing differences observed for low-energy collision induced dissociation of peptide ions having or lacking a mobile proton. To overcome this limitation, a deeper understanding of the dissociation chemistry of protonated peptides is needed. To this end use of the 'pathways in competition' (PIC) model that involves a detailed energetic and kinetic characterization of the major peptide fragmentation pathways (PFPs) is proposed. The known PFPs are described in detail including all the pre-dissociation, dissociation, and post-dissociation events. It is our hope that studies to further extend PIC will lead to semi-quantative understanding of the MS/MS spectra of protonated peptides which could be used to develop refined bioinformatics algorithms for MS/MS based proteomics. Experimental and computational data on the fragmentation of protonated peptides are reevaluated from the point of view of the PIC model considering the mechanism, energetics, and kinetics of the major PFPs. Evidence proving semi-quantitative predictability of some of the ion intensity relationships (IIRs) of the MS/MS spectra of protonated peptides is presented. PMID:15389847

Paizs, Béla; Suhai, Sándor

287

The search for proton decay  

Microsoft Academic Search

Techniques used to search for evidence of proton or neutron decay (by one of the 32 theoretically possible modes) are examined, and some preliminary results are summarized, in a general review. The physical principles of proton decay are reviewed; the operation of water-Cerenkov and layered tracking detectors is explained and illustrated with diagrams; the 8000-ton water detector (equipped with 2048

J. M. Losecco; Frederick Reines; Daniel Sinclair

1985-01-01

288

Image, Image, Image  

ERIC Educational Resources Information Center

|With all the talk today about accountability, budget cuts, and the closing of programs in public education, teachers cannot overlook the importance of image in the field of industrial technology. It is very easy for administrators to cut ITE (industrial technology education) programs to save school money--money they might shift to teaching the…

Howell, Robert T.

2004-01-01

289

Two-Proton Correlations in the Decay of Fe45  

NASA Astrophysics Data System (ADS)

The decay of extremely neutron-deficient Fe45 has been studied in detail by means of a novel type of a gaseous detector employing digital imaging to record tracks of charged particles. The two-proton radioactivity channel was clearly identified. For the first time, the angular and energy correlations between two protons emitted from the nuclear ground state were determined, indicating the genuine three-body character of this decay. The half-life of Fe45 was found to be 2.6±0.2ms and the observed 2p decay branching ratio is 70±4%.

Miernik, K.; Dominik, W.; Janas, Z.; Pfützner, M.; Grigorenko, L.; Bingham, C. R.; Czyrkowski, H.; ?wiok, M.; Darby, I. G.; D?browski, R.; Ginter, T.; Grzywacz, R.; Karny, M.; Korgul, A.; Ku?mierz, W.; Liddick, S. N.; Rajabali, M.; Rykaczewski, K.; Stolz, A.

2007-11-01

290

First observation of two-proton radioactivity in Ni48  

NASA Astrophysics Data System (ADS)

The decay of the extremely neutron-deficient Ni48 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 Ni48. Two decays represent ?-delayed proton emission. The half-life of Ni48 is determined to be T1/2=2.1-0.4+1.4 ms.

Pomorski, M.; Pfützner, M.; Dominik, W.; Grzywacz, R.; Baumann, T.; Berryman, J. S.; Czyrkowski, H.; D?browski, R.; Ginter, T.; Johnson, J.; Kami?ski, G.; Ku?niak, A.; Larson, N.; Liddick, S. N.; Madurga, M.; Mazzocchi, C.; Mianowski, S.; Miernik, K.; Miller, D.; Paulauskas, S.; Pereira, J.; Rykaczewski, K. P.; Stolz, A.; Suchyta, S.

2011-06-01

291

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

292

Voltage-Gated Proton Channels  

PubMed Central

The history of research on voltage-gated proton channels is recounted, from their proposed existence in dinoflagellates by Hastings in 1972 and their demonstration in snail neurons by Thomas and Meech in 1982, to the discovery (after a decade of controversy) of genes that unequivocally code for proton channels in 2006. Voltage-gated proton channels are perfectly selective for protons, conduct deuterons half as well, and the conductance is strongly temperature dependent. These properties are consistent with a conduction mechanism involving hydrogen-bonded-chain transfer, in which the selectivity filter is a titratable amino acid residue. Channel opening is regulated stringently by pH such that only outward current is normally activated. Main functions of proton channels include acid extrusion from cells and charge compensation for the electrogenic activity of the phagocyte NADPH oxidase. Genetic approaches hold the promise of rapid progress in the near future.

DeCoursey, Thomas E.

2013-01-01

293

The precision of proton range calculations in proton radiotherapy treatment planning: experimental verification of the relation between CT-HU and proton stopping power.  

PubMed

The precision in proton radiotherapy treatment planning depends on the accuracy of the information used to calculate the stopping power properties of the tissues in the patient's body. This information is obtained from computed tomography (CT) images using a calibration curve to convert CT Hounsfield units into relative proton stopping power values. The validity of a stoichiometric method to create the calibration curve has been verified by measuring pairs of Hounsfield units and stopping power values for animal tissue samples. It was found that the agreement between measurement and calibration curve is better than 1% if beam hardening effects in the acquisition of the CT images can be neglected. The influence of beam hardening effects on the quantitative reading of the CT measurements is discussed and an estimation for the overall range precision of proton beams is given. It is expected that the range of protons in the human body can be controlled to better than +/-1.1% of the water equivalent range in soft tissue and +/-1.8% in bone, which translates into a range precision of about 1-3 mm in typical treatment situations. PMID:9651027

Schaffner, B; Pedroni, E

1998-06-01

294

Proton Auroral Emissions without Electron Auroral Emissions in Long-lasting Complex Substorms  

NASA Astrophysics Data System (ADS)

The SI-12 and WIC FUV instruments aboard the IMAGE satellite provide a unique ability to compare LBH and proton auroral emissions. The auroral power allows for the examination of the relationship of proton and electron emissions. In the past, measurements in the LBH band have been used to identify substorms. There are, however, cases where there is significant proton auroral emission while there is little to no electron emission in the LBH band. During intense, long-lasting complex substorms it is possible that while the WIC images show a decreasing intensity and entry into a more recovered state. At the same time, images from the SI-12 camera show increased intensities and possibly further substorms seen only in the proton emissions. An example of this can be seen in the events of November 15, 2001 from 1700-2200 UT. An investigation of this event will be presented and possible explanations of these events will be put forth.

Bryant, C. R.; Murphree, J. S.; Mende, S.

2008-12-01

295

Proton decay: 1982  

SciTech Connect

Employing the current world average ..lambda../sub MS/ = 0.160 GeV as input, the minimal Georgi-Glashow SU(5) model predicts sin/sup 2/theta/sub W/(m/sub W/) = 0.214, m/sub b//m/sub tau/ approx. = 2.8 and tau/sub p/ approx. = (0.4 approx. 12) x 10/sup 29/ yr. The first two predictions are in excellent agreement with experiment; but the implied proton lifetime is already somewhat below the present experimental bound. In this status report, uncertainties in tau/sub p/ are described and effects of appendages to the SU(5) model (such as new fermion generations, scalars, supersymmetry, etc.) are examined.

Marciano, W.J.

1982-03-04

296

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

297

IMAGES, IMAGES, IMAGES  

SciTech Connect

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

Marcus, A.

1980-07-01

298

Dosimetric uncertainty in prostate cancer proton radiotherapy  

SciTech Connect

Purpose: The authors we evaluate the uncertainty in proton therapy dose distribution for prostate cancer due to organ displacement, varying penumbra width of proton beams, and the amount of rectal gas inside the rectum. Methods and Materials: Proton beam treatment plans were generated for ten prostate patients with a minimum dose of 74.1 cobalt gray equivalent (CGE) to the planning target volume (PTV) while 95% of the PTV received 78 CGE. Two lateral or lateral oblique proton beams were used for each plan. The authors we investigated the uncertainty in dose to the rectal wall (RW) and the bladder wall (BW) due to organ displacement by comparing the dose-volume histograms (DVH) calculated with the original or shifted contours. The variation between DVHs was also evaluated for patients with and without rectal gas in the rectum for five patients who had 16 to 47 cc of visible rectal gas in their planning computed tomography (CT) imaging set. The uncertainty due to the varying penumbra width of the delivered protons for different beam setting options on the proton delivery system was also evaluated. Results: For a 5 mm anterior shift, the relative change in the RW volume receiving 70 CGE dose (V{sub 70}) was 37.9% (5.0% absolute change in 13.2% of a mean V{sub 70}). The relative change in the BW volume receiving 70 CGE dose (V{sub 70}) was 20.9% (4.3% absolute change in 20.6% of a mean V{sub 70}) with a 5 mm inferior shift. A 2 mm penumbra difference in beam setting options on the proton delivery system resulted in the relative variations of 6.1% (0.8% absolute change) and 4.4% (0.9% absolute change) in V{sub 70} of RW and BW, respectively. The data show that the organ displacements produce absolute DVH changes that generally shift the entire isodose line while maintaining the same shape. The overall shape of the DVH curve for each organ is determined by the penumbra and the distance of the target in beam's eye view (BEV) from the block edge. The beam setting option producing a 2 mm sharper penumbra at the isocenter can reduce the magnitude of maximal doses to the RW by 2% compared to the alternate option utilizing the same block margin of 7 mm. The dose to 0.1 cc of the femoral head on the distal side of the lateral-posterior oblique beam is increased by 25 CGE for a patient with 25 cc of rectal gas. Conclusion: Variation in the rectal and bladder wall DVHs due to uncertainty in the position of the organs relative to the location of sharp dose falloff gradients should be accounted for when evaluating treatment plans. The proton beam delivery option producing a sharper penumbra reduces maximal doses to the rectal wall. Lateral-posterior oblique beams should be avoided in patients prone to develop a large amount of rectal gas.

Lin Liyong; Vargas, Carlos; Hsi Wen; Indelicato, Daniel; Slopsema, Roelf; Li Zuofeng; Yeung, Daniel; Horne, Dave; Palta, Jatinder [University of Florida Proton Therapy Institute, Jacksonville, Florida 32206 (United States)

2008-11-15

299

[Imaging features of CNS tuberculosis].  

PubMed

CNS tuberculosis remains relatively frequent in endemic regions. Both CT and MRI are valuable for diagnosis. Even though non-specific, MRI including diffusion-weighted imaging and proton spectroscopy is more sensitive than CT for detection of some lesions. The purpose of this paper is to illustrate the imaging features of CNS tuberculosis. PMID:18354351

Semlali, S; El Kharras, A; Mahi, M; Hsaini, Y; Benameur, M; Aziz, N; Chaouir, S; Akjouj, S

2008-02-01

300

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

301

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

302

Proton diffusion along biological membranes  

NASA Astrophysics Data System (ADS)

Biological surfaces are known to be capable of retaining protons and facilitating their lateral diffusion. Since the surface dynamically exchanges protons with the bulk, the proton movement from a source to a target at the surface acquires a complicated pattern of coupled surface and bulk (2D + 3D) diffusion of which the main feature is that the surface acts as a proton-collecting antenna enhancing the proton flux from the bulk. A phenomenological model of this process is reviewed and its applications to recent experiments on lipid bilayers and small unilaminar vesicles are discussed. The model (i) introduces the important notions of the fast and slow regimes of proton exchange between the surface and the bulk, (ii) permits evaluation of the antenna radius and amplification coefficient in both regimes, (iii) explains the observed macroscopically large distances (in the micrometer range; Antonenko and Pohl 1998 FEBS Lett. 429 197) that the proton can travel along lipid membranes embedded into pure aqueous solutions, and (iv) predicts the dependence of the steady-state proton flux and the kinetics of the non-stationary diffusion upon the buffer concentration in buffered solutions. The surface diffusion coefficient for small unilaminar vesicles is calculated from experimental data (Sandén et al 2010 Proc. Natl Acad. Sci. USA 107 4129) to be 1 × 10 - 5 cm2 s - 1. The dependence of the shape of the kinetic curves representing protonation/deprotonation of a lipid-bound pH-sensitive dye attached to a planar bilayer lipid membrane upon the buffer concentration (Serowy et al 2003 Biophys. J. 84 1031) and the effect of changing the membrane composition (Antonenko and Pohl 2008 Eur. Biophys. J. 37 865) are explained.

Medvedev, E. S.; Stuchebrukhov, A. A.

2011-06-01

303

A generalized series approach to MR spectroscopic imaging  

Microsoft Academic Search

The problem of precise spatial localization of spectral information in magnetic resonance (MR) spectroscopic imaging is addressed. A novel method, called GSLIM (generalized spectral location by imaging), is proposed to make possible the marriage of high-resolution proton imaging with spectroscopic imaging and localization. This method improves on the conventional Fourier series inversion method used in chemical shift imaging (CSI) and

Zhi-Pei Liang; Paul C. Lauterbur

1991-01-01

304

In Vivo Proton Beam Range Verification Using Spine MRI Changes  

SciTech Connect

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

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

2010-09-01

305

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

306

Relaxation of Protons by Radicals in Rotationally Immobilized Proteins  

PubMed Central

Proton spin-lattice relaxation by paramagnetic centers may be dramatically enhanced if the paramagnetic center is rotationally immobilized in the magnetic field. The details of the relaxation mechanism are different from those appropriate to solutions of paramagnetic relaxation agents. We report here large enhancements in the proton spin-lattice relaxation rate constants associated with organic radicals when the radical system is rigidly connected with a rotationally immobilized macromolecular matrix such as a dry protein or a cross-linked protein gel. The paramagnetic contribution to the protein-proton population is direct and distributed internally among the protein protons by efficient spin diffusion. In the case of a cross-linked-protein gel, the paramagnetic effects are carried to the water spins indirectly by chemical exchange mechanisms involving water molecule exchange with rare long-lived water molecule binding sites on the immobilized protein and proton exchange. The dramatic increase in the efficiency of spin relaxation by organic radicals compared with metal systems at low magnetic field strengths results because the electron relaxation time of the radical is orders of magnitude larger than that for metal systems. This gain in relaxation efficiency provides completely new opportunities for the design of spin-lattice relaxation based contrast agents in magnetic imaging and also provides new ways to examine intramolecular protein dynamics.

Korb, Jean-Pierre; Diakova, Galina; Goddard, Yanina; Bryant, Robert G.

2007-01-01

307

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

308

POLARIZED PROTON COLLISIONS AT RHIC.  

SciTech Connect

The Relativistic Heavy Ion Collider provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC. In 2002, polarized proton beams were first accelerated to 100 GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. Optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limited conditions are reported.

BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; ET AL.

2005-05-16

309

Update of Proton Driven Plasma Wakefield Acceleration  

SciTech Connect

In this paper, the update of proton driven plasma wakefield acceleration (PDPWA) is given. After a brief introduction to the scheme of PDPWA, a future demonstration experiment is discussed. The particle-in-cell simulation results based on the realistic proton beams from the CERN Super Proton Synchrotron (SPS) are presented, followed by a simulation study of proton bunch compression.

Xia, G.; Caldwell, A. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Lotov, K. [Budker Institute for Nuclear Physics, Novisibirsk (Russian Federation); Pukhov, A.; Kumar, N. [Duesseldorf University, Duesseldorf (Germany); An, W.; Lu, W.; Mori, W. B.; Joshi, C. [University of California, Los Angeles, CA (United States); Huang, C. [Los Alamos National Laboratory, NM (United States); Muggli, P. [University of Southern California, CA (United States); Assmann, R.; Zimmermann, F. [CERN, Geneva (Switzerland)

2010-11-04

310

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

311

Parametric Model for Astrophysical Proton-Proton Interactions and Applications  

SciTech Connect

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

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

2008-01-29

312

Decay rules in proton emission  

SciTech Connect

We give a simple relation, connecting the logarithm of the half-life, corrected by the centrifugal barrier, with the Coulomb parameter in proton decay processes. The reduced experimental data lie on two straight lines as a result of a sudden change in the nuclear shape, marking two regions of deformation, divided by the charge number Z = 68. This feature provides a powerful tool to assign experimentally quantum numbers in proton emitters.

Delion, D. S. ['Horia Hulubei' National Institute of Physics and Nuclear Engineering, POB MG-6, Bucharest-Magurele (Romania); Litta, R. J.; Wyss, R. [KTH, Alba Nova University Center, SE-10691 Stockholm (Sweden)

2007-11-30

313

Proton Structure and Atomic Physics  

SciTech Connect

We discuss a precise determination of the polarizability and other proton structure dependent contributions to the hydrogen hyperfine splitting, based heavily on the most recent published data on proton spin dependent structure functions from the EG1 experiment at the Jefferson Laboratory. As a result, the total calculated hyperfine splitting now has a standard deviation slightly under 1 part-per-million, and is about 1 standard deviation away from the measured value.

Carlson, Carl E. [Physics Department, College of William and Mary, Williamsburg, VA 23187-8795 (United States)

2009-07-27

314

Proton driver power supply system  

SciTech Connect

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

C. Jach and D. Wolff

2002-06-03

315

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

316

Simple approach to two-proton emission  

NASA Astrophysics Data System (ADS)

The two-proton decay process is studied by using a simple approach within the framework of scattering theory. We assume that the decaying nucleus is in a pairing state and, therefore, the two-particle wave function on the nuclear surface corresponds to the two protons moving in time-reversed states. This allows us to sustain a simplified version of the decay where the protons are simultaneously emitted with the same energies. We thus obtain a coupled system of radial equations with outgoing boundary conditions. We use similar proton-proton interactions to solve BCS equations and to describe external two-proton dynamics. A strong dependence of the pairing gap and decay width upon the proton-proton interaction strength is revealed. The experimental half-lives of 45Fe and 48Ni are reproduced by using a realistic proton-proton interaction.

Delion, D. S.; Liotta, R. J.; Wyss, R.

2013-03-01

317

Proton Spectrometer Belt Research (PSBR)  

NASA Astrophysics Data System (ADS)

The National Reconnaissance Office (NRO), NASA, the Air Force Research Laboratory (AFRL), the Aerospace Corporation, the Los Alamos National Laboratory (LANL) and the Naval Research Laboratory (NRL) have jointly formed the Proton Spectrometer Belt Research (PSBR) program to meet two primary objectives: to measure the high-energy proton spectrum by placing the Relativistic Proton Spectrometer (RPS) instrument on board the Radiation Belt Storm Probes (RBSP) spacecraft to measure the inner Van Allen belt protons with energies from 50 MeV to 2 GeV, and to produce the next generation radiation belt models. Presently, the intensity of trapped protons with energies beyond about 150 MeV is not well known and thought to be underestimated in existing specification models. Such protons are known to pose a number of hazards to astronauts and spacecraft; including total ionizing dose, displacement damage, single event effects, and nuclear activation. The RPS addresses a priority highly ranked by the scientific and technical community and will extend the measurement capability of the RBSP mission to a range beyond that originally planned. The PSBR program will use the RPS data, coupled with other data sets, to upgrade existing radiation belt models, significantly improving the radiation hazards specified by increasing the spectral and spatial coverage, and the time-correlated probability of occurrence statistics, quantifying the model accuracy and uncertainty.

Byers, David

318

Proton Spectrometer Belt Research (PSBR)  

NASA Astrophysics Data System (ADS)

The National Reconnaissance Office (NRO), NASA, the Air Force Research Laboratory (AFRL), the Aerospace Corporation, the Los Alamos National Laboratory (LANL) and the Naval Research Laboratory (NRL) have jointly formed the Proton Spectrometer Belt Research (PSBR) program to meet two primary objectives: to measure the high-energy proton spectrum by placing the Relativistic Proton Spectrometer (RPS) instrument on board the Radiation Belt Storm Probes (RBSP) spacecraft to measure the inner Van Allen belt protons with energies from 50 MeV to 2 GeV, and to produce the next generation radiation belt models. Presently, the intensity of trapped protons with energies beyond about 150 MeV is not well known and thought to be underestimated in existing specification models. Such protons are known to pose a number of hazards to astronauts and spacecraft; including total ionizing dose, displacement damage, single event effects, and nuclear activation. The RPS addresses a priority highly ranked by the scientific and technical community and will extend the measurement capability of the RBSP mission to a range beyond that originally planned. The PSBR program will use the RPS data, coupled with other data sets, to upgrade existing radiation belt models, significantly improving the radiation hazards specified by increasing the spectral and spatial coverage, and the time-correlated probability of occurrence statistics, quantifying the model accuracy and uncertainty.

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

2008-12-01

319

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

320

The Temporal Evolution of Proton Precipitation Associated with the Plasmaspheric Plume  

NASA Astrophysics Data System (ADS)

The temporal evolution of afternoon sector proton precipitation observed by a global auroral imager is examined in detail for two case events. We focus on precipitation regions that are magnetically mapped to the plasmapause and plasmaspheric plume regions. The spatial and temporal variation of the plume-associated precipitation, including its relationship to the main proton oval, is dependent on the prevailing solar wind and magnetospheric driving conditions. Two contrasting events are presented here in association with 1) a substorm injection and 2) a northward IMF turning. We find that proton precipitation within the plasmaspheric plume is a persistent feature during geomagnetically disturbed periods, but the precipitation regions only appear latitudinally detached from the main proton oval under specific conditions. The evolution in both time and space of the plume-associated precipitation regions is consistent with theoretical predictions for EMIC wave scattering of protons in the ring current energy range.

Spasojevic, M.; Fuselier, S. A.

2009-12-01

321

Heteronuclear proton assisted recoupling  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

322

Heteronuclear proton assisted recoupling  

PubMed Central

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

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

2011-01-01

323

Three-dimensional hydrogen microscopy using a high-energy proton probe  

NASA Astrophysics Data System (ADS)

It is a challenge to measure two-dimensional or three-dimensional (3D) hydrogen profiles on a micrometer scale. Quantitative hydrogen analyses of micrometer resolution are demonstrated utilizing proton-proton scattering at a high-energy proton microprobe. It has more than an-order-of-magnitude better position resolution and in addition higher sensitivity than any other technique for 3D hydrogen analyses. This type of hydrogen imaging opens plenty room to characterize microstructured materials, and semiconductor devices or objects in microbiology. The first hydrogen image obtained with a 10 MeV proton microprobe shows the hydrogen distribution of the microcapillary system being present in the wing of a mayfly and demonstrates the potential of the method.

Dollinger, G.; Reichart, P.; Datzmann, G.; Hauptner, A.; Körner, H.-J.

2003-01-01

324

Electron-proton dynamics for long proton bunches in high intensity proton rings  

NASA Astrophysics Data System (ADS)

Electron clouds in intense space charge dominated proton beams may cause instabilities and emittance growth. Colleagues at the Oak Ridge National Laboratory (ORNL) and I have developed an electron cloud module and implemented it into the ORBIT Code for beam dynamics in high intensity rings. This new module includes full 3D descriptions of the proton beam bunch and the electron cloud, including their space charge interactions and their motion in external electric and magnetic fields. The two main sources of electrons are primary electrons caused by lost protons hitting the vacuum chamber walls and secondary emitted electrons caused by electrons hitting the wall. For the latter we adopt a set of models based on those of M. Pivi and M. Furman. This dissertation presents the development of the new electron cloud module, including benchmarks demonstrating its capability to examine the effects of the electron cloud on the proton beam and simulation studies of electron cloud dynamics. These studies include the sensitivity of the electron cloud properties to different proton beam profiles and reproduction of experimental results from the proton storage ring at Los Alamos National Laboratory.

Sato, Yoichi

325

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

2013-09-19

326

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

327

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

SciTech Connect

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

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

2007-07-01

328

Proton auroral intensification induced by interplanetary shock on 7 November 2004  

NASA Astrophysics Data System (ADS)

We report a shock-induced auroral intensification event observed by the IMAGE spacecraft on 7 November 2004. The comparison of simultaneous auroral snapshots, obtained from FUV-SI12 and FUV-SI13 cameras onboard IMAGE spacecraft, indicates the dominance of proton precipitation (rather than electron precipitation) throughout the auroral oval region. The proton aurora in the postnoon sector showed the most significant intensification, with luminosity increasing by 5 times or more. We describe the main characteristics of interplanetary parameters observed by the ACE and Geotail satellites and plasma parameters within the mapped precipitation region detected by the Los Alamos National Laboratory 1990-1995 satellite. The generation mechanism of postnoon proton auroral intensification is further investigated on the basis of these observations. The estimated increase of loss cone size was not enough to produce the required proton auroral precipitation enhancement. The expected oxygen band electromagnetic ion cyclotron waves (no available observation), in the highly fluctuating density region during the shock period, might contribute to the enhanced precipitation of auroral protons. Our new finding is that the shock-driven buildup of 1-10 keV proton fluxes could account for the observed proton auroral intensification.

Su, Zhenpeng; Zong, Qiu-Gang; Yue, Chao; Wang, Yongfu; Zhang, Hui; Zheng, Huinan

2011-08-01

329

Theoretical calculation of proton mobility for collective surface proton transport.  

PubMed

We present a theoretical study of surface proton mobility at a minimally hydrated array of protogenic surface groups. At dense packing, the array assembles into a 2D bicomponent lattice that is formed by sulfonate anions, which are only allowed to fluctuate about fixed equilibrium positions, and mobile hydronium ions. Proton transport on the lattice proceeds by collective translocations of hydronium ions. This type of motion is described within the framework of soliton theory. Our main objective in this article is to establish the relation between microscopic surface structure and effective proton mobility. To this end, we present an approach to calculate microscopic interaction parameters that determine hydronium ion motion. The developed formalism enables us to theoretically derive an expression for soliton mobility at a given surface structure and compare it with experimentally measured mobilities. PMID:23848749

Golovnev, Anatoly; Eikerling, Michael

2013-06-14

330

Theoretical calculation of proton mobility for collective surface proton transport  

NASA Astrophysics Data System (ADS)

We present a theoretical study of surface proton mobility at a minimally hydrated array of protogenic surface groups. At dense packing, the array assembles into a 2D bicomponent lattice that is formed by sulfonate anions, which are only allowed to fluctuate about fixed equilibrium positions, and mobile hydronium ions. Proton transport on the lattice proceeds by collective translocations of hydronium ions. This type of motion is described within the framework of soliton theory. Our main objective in this article is to establish the relation between microscopic surface structure and effective proton mobility. To this end, we present an approach to calculate microscopic interaction parameters that determine hydronium ion motion. The developed formalism enables us to theoretically derive an expression for soliton mobility at a given surface structure and compare it with experimentally measured mobilities.

Golovnev, Anatoly; Eikerling, Michael

2013-06-01

331

Shock-Wave and Detonation Studies at ITEP-TWAC Proton Radiography Facility  

NASA Astrophysics Data System (ADS)

In recent years studies of shock and detonation wave phenomena at extreme dynamic conditions were performed at proton radiography facility developed at the 800 MeV proton beam line of ITEP Terawatt Accelerator (ITEP-TWAC). The facility provides a multi-frame imaging capability at 50 ?m spatial and 70 ns temporal resolution. The results of latest studies conducted there are presented, including explosion and detonation of pressed and emulsion high explosives, shock-induced dense non-ideal plasma of argon and xenon and shock loading of non-uniform metal surfaces. New compact explosive generators developed specifically for a use at proton radiography facilities are also presented.

Kolesnikov, Sergey; Dudin, Sergey; Lavrov, Vladimir; Nikolaev, Dmitry; Mintsev, Victor; Shilkin, Nikolay; Ternovoi, Vladimir; Utkin, Alexander; Yakushev, Vladislav; Yuriev, Denis; Fortov, Vladimir; Golubev, Alexander; Kantsyrev, Alexey; Shestov, Lev; Smirnov, Gennady; Turtikov, Vladimir; Sharkov, Boris; Burtsev, Vasily; Zavialov, Nikolay; Kartanov, Sergey; Mikhailov, Anatoly; Rudnev, Alexey; Tatsenko, Mikhail; Zhernokletov, Mikhail

2011-06-01

332

Export of alpha-amylase by Bacillus amyloliquefaciens requires proton motive force.  

PubMed Central

The secretion of protein directly into the extracellular medium by Bacillus amyloliquefaciens, a gram-positive bacterium, was shown to be dependent on proton motive force. When the electrochemical membrane potential gradient of protons was dissipated either by uncouplers or by valinomycin in combination with K+, a precursor form of alpha-amylase accumulated on the cellular membrane. The proton motive force could be dissipated without altering the intracellular level of ATP, indicating that the observed inhibition of export was not the result of decreased ATP concentration. Images

Muren, E M; Randall, L L

1985-01-01

333

Measurement of the Wolfenstein parameters for proton-proton and proton-neutron scattering at 500 MeV  

SciTech Connect

Using liquid hydrogen and liquid deuterium targets respectively, forward angle (ten degrees to sixty degrees in the center of Mass) free proton-proton and quasielastic proton-proton and proton-neutron triple scattering data at 500 MeV have been obtained using the high resolution spectrometer at the Los Alamos Meson Physics Facility. The data are in reasonable agreement with recent predictions from phase shift analyses, indicating that the proton-nucleon scattering amplitudes are fairly well determined at 500 MeV. 32 references.

Marshall, J.A.

1984-07-01

334

Proton therapy for hepatocellular carcinoma.  

PubMed

Proton radiotherapy has seen an increasing role in the treatment of hepatocellular carcinoma (HCC). Historically, external beam radiotherapy has played a very limited role in HCC due to a high incidence of toxicity to surrounding normal structures. The ability to deliver a high dose of radiation to the tumor is a key factor in improving outcomes in HCC. Advances in photon radiotherapy have improved dose conformity and allowed dose escalation to the tumor. However, despite these advances there is still a large volume of normal liver that receives a considerable radiation dose during treatment. Proton beams do not have an exit dose along the beam path once they enter the body. The inherent physical attributes of proton radiotherapy offer a way to maximize tumor control via dose escalation while avoiding excessive radiation to the remaining liver, thus increasing biological effectiveness. In this review we discuss the physical attributes and rationale for proton radiotherapy in HCC. We also review recent literature regarding clinical outcomes of using proton radiotherapy for the treatment of HCC. PMID:23359779

Ling, Ted C; Kang, Joseph I; Bush, David A; Slater, Jerry D; Yang, Gary Y

2012-12-01

335

Proton therapy for hepatocellular carcinoma  

PubMed Central

Proton radiotherapy has seen an increasing role in the treatment of hepatocellular carcinoma (HCC). Historically, external beam radiotherapy has played a very limited role in HCC due to a high incidence of toxicity to surrounding normal structures. The ability to deliver a high dose of radiation to the tumor is a key factor in improving outcomes in HCC. Advances in photon radiotherapy have improved dose conformity and allowed dose escalation to the tumor. However, despite these advances there is still a large volume of normal liver that receives a considerable radiation dose during treatment. Proton beams do not have an exit dose along the beam path once they enter the body. The inherent physical attributes of proton radiotherapy offer a way to maximize tumor control via dose escalation while avoiding excessive radiation to the remaining liver, thus increasing biological effectiveness. In this review we discuss the physical attributes and rationale for proton radiotherapy in HCC. We also review recent literature regarding clinical outcomes of using proton radiotherapy for the treatment of HCC.

Ling, Ted C.; Kang, Joseph I.; Bush, David A.; Slater, Jerry D.

2012-01-01

336

Intramolecular proton transfer in channelrhodopsins.  

PubMed

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

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

2013-02-19

337

Heavy quark photoproduction in proton-proton collisions  

SciTech Connect

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

Goncalves, V.P. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-090, Pelotas, RS (Brazil); Machado, M.V.T. [Universidade Estadual do Rio Grande do Sul-UERGS, Unidade de Bento Goncalves, CEP 95700-000, Bento Goncalves, RS (Brazil); High Energy Physics Phenomenology Group, GFPAE, IF-UFRGS, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS (Brazil)

2005-01-01

338

The donut and dynamic polarization effects in proton channeling through carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate the angular and spatial distributions of protons with an energy of 0.223 MeV after channeling them through an (11, 9) single-wall carbon nanotube of 0.2 ?m length. The proton incident angle is varied between 0 and 10 mrad, being close to the critical angle for channeling. We show that, as the proton incident angle increases and approaches the critical angle for channeling, a ring-like structure is developed in the angular distribution—the donut effect. We demonstrate that it is the rainbow effect. If the proton incident angle is between zero and half of the critical angle for channeling, the image force affects considerably the number and positions of the maxima of the angular and spatial distributions. However, if the proton incident angle is close to the critical angle for channeling, its influence on the angular and spatial distributions is considerably decreased. We demonstrate that an increase of the proton incident angle can lead to a significant rearrangement of the propagating protons within the nanotube. This effect may be used to locate atomic impurities in nanotubes as well as for creating nanosized proton beams to be used in materials science, biology and medicine.

Borka, D.; Mowbray, D. J.; Miškovi?, Z. L.; Petrovi?, S.; Neškovi?, N.

2010-04-01

339

Thermalization of pair plasma with proton loading  

SciTech Connect

We study kinetic evolution of nonequilibrium optically thick electron-positron plasma towards thermal equilibrium solving numerically relativistic Boltzmann equations with energy per particle ranging from 0.1 to 10 MeV. We generalize our results presented in [1], considering proton loading of the pair plasma. Proton loading introduces new characteristic timescales essentially due to proton-proton and proton-electron Coulomb collisions. Taking into account not only binary but also triple direct and inverse interactions between electrons, positrons, photons and protons we show that thermal equilibrium is reached on a timescale t{sub th}{approx_equal}10{sup -11} sec.

Aksenov, A. G. [Institute for Computer-Aided Design, Russian Academy of Sciences, Vtoraya Brestskaya 19/18, Moscow, 123056 (Russian Federation); Ruffini, R.; Vereshchagin, G. V. [ICRANet p.le della Repubblica, 10, 65100 Pescara, Italy and ICRA and University of Rome 'Sapienza', Physics Department, p.le A. Moro 5, 00185 Rome (Italy)

2009-05-03

340

Proton periphery activated by multiparticle dynamics  

NASA Astrophysics Data System (ADS)

It is shown that protons become more active at the periphery with increase of their collision energy. By computing the impact parameter distribution of the proton-proton overlap function at LHC energies and comparing it with ISR (and Spp¯S for pp¯) data, we conclude that the peripheral region of protons plays an increasing role in the rise of total cross sections through multiparticle dynamics. The size of the proton as well as its blackness increase with energy. The protons become more black both in the central region and, especially, at the periphery. This effect can be related to the ridge phenomenon and to the inelastic diffraction processes at LHC energies.

Dremin, I. M.; Nechitailo, V. A.

2013-10-01

341

Proton aurora and substorm intensifications  

SciTech Connect

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

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

1993-10-01

342

Proton interactions with high multiplicity  

SciTech Connect

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

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

2012-06-15

343

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

344

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

SciTech Connect

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 {approx}1 mm agreement with direct 4DCT measurement. Quantitative WEL variation studies showed that the proton radiograph is a good representation of WEL changes from entrance to distal of the target. Conclusions: MCNPX simulation results showed that TRRT can accurately track the motion of the tumor and detect the WEL variations. Image quality was optimized by choosing proton energy, testing parameters of image reconstruction algorithm, and comparing to ground truth 4DCT. The future study will demonstrate the feasibility of using the time resolved proton radiography as an imaging tool for proton treatments of lung tumors.

Han Bin; Xu, X. George; Chen, George T. Y. [Nuclear Engineering and Engineering Physics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)

2011-04-15

345

Proton-radiography-based quality assurance of proton range compensator  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

346

Proton-radiography-based quality assurance of proton range compensator.  

PubMed

The aim of this work was to study the feasibility of proton radiography (pRad) as a patient-specific range compensator (RC) quality assurance (QA) tool and to validate its clinical utility by performing QA on RCs having three kinds of possible defects. In order to achieve pRad for a single EBT film, proton beam currents were modulated with new weighting factors, maximizing the linearity of optical-density-to-thickness ratio. Two RCs, examined to be accurately manufactured as planned, were selected to estimate the feasibility of our pRad. The optical densities of the EBT film on which the RC was irradiated with the modulated proton beam were digitized to pixel values (pv) and then converted to thickness using a thickness-pv calibration curve. The thickness information on the pRad was compared with plan data that had been extracted from treatment planning system. The mean thickness difference (TD) over the flat RC regions was calculated as 0.39 mm, and the standard deviation as 0.22 mm, and the proton scattering effect was analyzed by step phantom measurement. Even proton scattering effected a TD of over 1 mm in the large gradient region, the percentage of pixels over the acceptance criterion was only within 1.11% and 3.49%, respectively, when a 1 mm distance to agreement tolerance limit was applied. The QA results for both precisely and imprecisely manufactured RCs demonstrated the high potential utility and clinical applicability of the pRad-based RC QA tool. PMID:24002543

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

2013-09-03

347

Imaging of brain metastases.  

PubMed

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

2013-05-02

348

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.

Fink, Kathleen R.; Fink, James R.

2013-01-01

349

Fast neutron production from lithium converters and laser driven protons  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

350

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

351

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

PubMed

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. PMID:22609618

Amos, Richard A; Woodward, Wendy A

2012-05-19

352

Proton range uncertainty due to bone cement injected into the vertebra in radiation therapy planning.  

PubMed

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. PMID:20970987

Lim, Young Kyung; Hwang, Ui-Jung; Shin, Dongho; Kim, Dong Wook; Kwak, Jungwon; Yoon, Myonggeun; Lee, Doo Hyun; Lee, Se Byeong; Lee, Sang-Yeob; Park, Sung Yong; Pyo, Hong Ryeol

2010-10-23

353

Proton Pumps: Mechanism of Action and Applications.  

National Technical Information Service (NTIS)

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

J. K. Lanyi A. Pohorille

2001-01-01

354

Proton Pump Inhibitors (PPIs) Video: Transcript  

Center for Drug Evaluation (CDER)

... Proton Pump Inhibitors (PPIs) Video: Transcript. Return to Proton Pump Inhibitors (PPIs) Video page. We're at the US Food ... More results from www.fda.gov/drugs/resourcesforyou/healthprofessionals

355

Effect of anatomic motion on proton therapy dose distributions in prostate cancer treatment  

SciTech Connect

Purpose: To determine the dosimetric impact of interfraction anatomic movements in prostate cancer patients receiving proton therapy. Methods and Materials: For each of the 10 patients studied, 8 computed tomography (CT) scans were selected from sets of daily setup CT images that were acquired from a cohort of prostate cancer patients. The images were acquired in the treatment room using the CT-on-rails system. First, standard proton therapy and intensity-modulated radiation therapy (IMRT) plans were designed for each patient using standard modality-specific methods. The images, the proton plan, and the IMRT plan were then aligned to the eight CT images based on skin marks. The doses were recalculated on these eight CT images using beam from the standard plans. Second, the plans were redesigned and evaluated assuming a smaller clinical target volume to planning target volume margin (3 mm). The images and the corresponding plans were then realigned based on the center of volume of the prostate. Dose distributions were evaluated using isodose displays, dose-volume histograms, and target coverage. Results: For the skin-marker alignment method, 4 of the 10 IMRT plans were deficient, whereas 3 of 10 proton plans were compromised. For the alignment method based on the center of volume of the prostate, only the proton plan for 1 patient was deficient, whereas 3 of the 10 IMRT plans were suboptimal. Conclusion: A comparison of passively scattered proton therapy and highly conformal IMRT plans for prostate cancer revealed that the dosimetric impact of interfractional anatomic motions was similar for both modalities.

Zhang Xiaodong [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)]. E-mail: xizhang@mdanderson.org; Dong, Lei [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Lee, Andrew K. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Cox, James D. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Kuban, Deborah A. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Zhu, Ron X. [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Wang Xiaochun [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Li Yupeng [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Newhauser, Wayne D. [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Gillin, Michael [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Mohan, Radhe [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

2007-02-01

356

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

357

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

PubMed Central

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

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

2011-01-01

358

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

NASA Astrophysics Data System (ADS)

Image guidance using implanted fiducial markers is commonly used to ensure accurate and reproducible target positioning in radiation therapy for prostate cancer. The ideal fiducial marker is clearly visible in kV imaging, does not perturb the therapeutic dose in the target volume and does not cause any artifacts on the CT images used for treatment planning. As yet, ideal markers that fully meet all three of these criteria have not been reported. In this study, 12 fiducial markers were evaluated for their potential clinical utility in proton radiation therapy for prostate cancer. In order to identify the good candidates, each fiducial was imaged using a CT scanner as well as a kV imaging system. Additionally, the dose perturbation caused by each fiducial was quantified using radiochromic film and a clinical proton beam. Based on the results, three fiducials were identified as good candidates for use in proton radiotherapy of prostate cancer.

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

2011-08-01

359

MCNP5 for proton radiography  

Microsoft Academic Search

The developmental version of MCNPS has recently been extended to provide for continuous-energy transport of high-energy protons. This enhancement involves the incorporation of several significant new physics models into the code. Multiple Coulomb scattering is treated with an advanced model that takes account of projectile and nuclear target form factors. In the next version, this model will provide a coupled

H. G. Hughes; F. B. Brown; J. S. Bull; J. T. Goorley; R. C. Little; L. C. Liu; S. G. Mashnik; R. E. Prael; Elizabeth Carol Selcow; A. J. Sierk; J. E. Sweezy; J. D. Zumbro; N. V. Mokhov; S. Striganov; K. K. Gudima

2004-01-01

360

Gluon polarization in the proton  

SciTech Connect

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

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

2011-03-15

361

Electron, proton and related transfers  

NASA Astrophysics Data System (ADS)

Past and current developments in electron and proton transfer and in related fields are described. Broad classes of reactions have been considered from a unified viewpoint, which offers a variety of experimental predictions. This introductory lecture considers various aspects of this many-faceted field.

Marcus, R. A.

1982-09-01

362

^69Kr ?-delayed proton emission  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

363

Alpha Proton X ray Spectrometer.  

National Technical Information Service (NTIS)

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

R. Rieder H. Waeke T. Economou

1994-01-01

364

Alpha proton x ray spectrometer  

NASA Astrophysics Data System (ADS)

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

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

365

Rise in proton structure function.  

National Technical Information Service (NTIS)

By the choice of a new scale factor we obtain a good qualitative fit to the HERA data for the proton structure function in the small x region which exhibits double asymptotic scaling. Any scaling violations in the future measurements when made in smaller ...

Fazal-e-Aleem H. Rashid S. Ali

1996-01-01

366

Proton synchrotrons for cancer therapy  

Microsoft Academic Search

Synchrotrons have long been recognized for their superior capabilities in proton and heavy ion therapy. Their compactness and ease of beam energy control make them ideally suited to this application. The range of available intensities insures safety against high dose accidents such as have occurred with conventional electron accelerators. For heavy ion and heavy ion therapy, synchrotrons have been the

George B. Coutrakon

2001-01-01

367

Family symmetries and proton decay.  

National Technical Information Service (NTIS)

The proton decay modes p (yields) K(sup 0)e(sup +) and p (yields) K(sup 0)(mu)(sup +) may be visible in certain supersymmetric theories, and if seen would provide evidence for new flavor physics at extremely short distances. These decay modes can arise fr...

H. Murayama D. B. Kaplan

1994-01-01

368

Proton decay and grand unification  

Microsoft Academic Search

I review the theoretical and experimental status of proton decay theory and experiment. Regarding theory, I focus mostly but not only on grand unification. I discuss only the minimal, well established SU(5) and SO(10) models, both ordinary and supersymmetric. I show how the minimal realistic extensions of the original Georgi - Glashow model can lead to interesting LHC physics, and

Goran Senjanovic; Goran

2010-01-01

369

[Choice of proton pump inhibitors].  

PubMed

The criteria of choice of proton pump inhibitor at acid-dependent diseases such as gastroesophageal reflux, peptic ulcer, diseases associated with Helicobacter pylory are discussed in the article. The presented data of meta-analysis of efficiency (clinical-and-endoscopic, economical), safety and tolerance, cost and simplicity of use show that today rabeprasol (pariet) is the drug of choice. PMID:11881475

Starostin, B D

2001-12-01

370

Design of a proton computed tomography system for applications in proton radiation therapy  

Microsoft Academic Search

Proton computed tomography (pCT) has the potential to improve the accuracy of dose calculations for proton treatment planning, and will also be useful for pretreatment verification of patient positioning relative to the proton beam. A design study was performed to define the optimal approach to a pCT system based on specifications for applications in proton therapy. Conceptual and detailed design

Reinhard Schulte; Vladimir Bashkirov; Tianfang Li; Jerome Z. Liang; Klaus Mueller; Jason Heimann; Leah R. Johnson; Brian Keeney; H. F.-W. Sadrozinski; A. Seiden; D. C. Williams; Lan Zhang; Zheng Li; S. Peggs; T. Satogata; C. Woody

2003-01-01

371

Conceptual design of a proton computed tomography system for applications in proton radiation therapy  

Microsoft Academic Search

Proton computed tomography (pCT) has the potential to improve the accuracy of dose calculations for proton treatment planning, and will also be useful for pretreatment verification of patient positioning relative to the proton beam. A design study was performed to define the optimal approach to a pCT system based on specifications for applications in proton therapy. Conceptual and detailed design

Reinhard Schulte; Vladimir Bashkirov; Tianfang Li; Zhengrong Liang; Klaus Mueller; Jason Heimann; Leah R. Johnson; Brian Keeney; Hartmut F.-W. Sadrozinski; Abraham Seiden; David C. Williams; Lan Zhang; Zhang Li; Steven Peggs; Todd Satogata; Craig Woody

2004-01-01

372

Quantum mechanical methods for calculating proton tunneling splittings and proton-coupled electron transfer vibronic couplings  

Microsoft Academic Search

Development of quantum mechanical methods for the calculation of proton tunneling splittings and proton-coupled electron transfer vibronic couplings is presented in this thesis. The fundamental physical principles underlying proton transfer in the electronically adiabatic and nonadiabatic limits are illustrated by applying the quantum mechanical methods we developed to chemical systems exemplary of the electronically adiabatic and nonadiabatic proton-tunneling regimes. Overall,

Jonathan H. Skone

2008-01-01

373

The University of Pennsylvania/Walter Reed Army Medical Center proton therapy program.  

PubMed

The design of the proton therapy center being constructed at the University of Pennsylvania is based on several principles that distinguish it from other proton facilities. Among these principles is the recognition that advances in imaging, and particularly in functional imaging, will have a large impact on radiotherapy in the near future and that the conformation of proton dose distributions can utilize that information to a larger degree than other treatment techniques. The facility will contain four-dimensional CT-simulators, an MR-simulator capable of spectroscopy, and a PET-CT scanner. A second principle applied to the facility design is to incorporate into proton radiotherapy the recent progress in conventional radiotherapy; including imaging and monitoring of patients during treatment, imaging of soft tissue, accounting for respiratory motion, and expanding the use of intensity-modulated treatments. A third principle is to understand that the facility must be operated efficiently. To that end the specifications for the equipment have included requirements for high beam intensity, fast switching times between treatment rooms, a multileaf collimator to permit multiple fields to be treated quickly, and plans for an intelligent beam scheduler to determine where the beam can be best used at any given time. We expect to use "universal" nozzles, which can switch rapidly from scattering mode to scanning mode, and there will be a set-up room used for the first day of treatment to verify alignment rather than spend valuable time in a gantry room. Many of these ideas require development, including the applications of existing radiotherapy techniques to proton gantries, so a series of research and development projects have started to address these issues. Walter Reed Army Medical Center, which will provide a portal through which military personnel and their dependants can receive proton radiotherapy, is involved in several of these development projects as well as the creation of process to remotely perform treatment planning for the military patients under treatment at the proton facility. PMID:17668956

McDonough, James; Tinnel, Brent

2007-08-01

374

Radiative Corrections to Electron-Proton Scattering  

Microsoft Academic Search

The radiative corrections to the electron-proton scattering are calculated with the effects of the proton recoil taken into account. We assumed the experimental conditions of Hofstadter et al. at Stanford, namely only the final electrons are momentum-analyzed. The anisotropy in the maximum energy of photons which can be emitted and the radiation from the proton current are the two main

Yung-Su Tsai

1961-01-01

375

Proton hexality in local grand unification  

Microsoft Academic Search

Proton hexality is a discrete symmetry that avoids the problem of too fast proton decay in the supersymmetric extension of the standard model. Unfortunately it is inconsistent with conventional grand unification. We show that proton hexality can be incorporated in the scheme of “Local Grand Unification” discussed in the framework of model building in (heterotic) string theory.

Stefan Förste; Hans Peter Nilles; Saúl Ramos-Sánchez; Patrick K. S. Vaudrevange

2010-01-01

376

Proton hexality in local grand unification  

Microsoft Academic Search

Proton hexality is a discrete symmetry that avoids the problem of too fast proton decay in the supersymmetric extension of the standard model. Unfortunately it is inconsistent with conventional grand unification. We show that proton hexality can be incorporated in the scheme of ``Local Grand Unification'' discussed in the framework of model building in (heterotic) string theory.

Stefan Förste; Hans Peter Nilles; Saúl Ramos-Sánchez; Patrick K. S. Vaudrevange

2010-01-01

377

Magnetic mirroring in an incident proton beam  

Microsoft Academic Search

We point out that the influence of magnetic-field nonuniformity on redirecting the pitch angle of a particle is independent of the particle's charge and thus is identical for protons and neutral hydrogen atoms. Under certain circumstances one can then speak of ``magnetic mirroring'' of hydrogen atoms as well as of protons. In the case of an energetic proton beam incident

Marina Galand; Arthur D. Richmond

1999-01-01

378

Proton solvation and transport in complex environments  

Microsoft Academic Search

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

Matt K. Petersen

2006-01-01

379

THE ELECTROMAGNETIC STRUCTURE OF PROTONS AND NEUTRONS  

Microsoft Academic Search

The structures of protons and neutrons were studied, including the ; anomalous magnetic moment by electron scattering experiments. The results ; indicated that the protons and neutrons are made up of nuclei surrounded by ; clouds of charge. The charge distribution of the proton and neutron possesses a ; nucleus containing 35% of the charge and with a radius of

Schopper

1961-01-01

380

The size of the proton.  

PubMed

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

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

2010-07-01

381

Proton Aurora and Trapped Particle Substorm Dynamics Compared  

NASA Astrophysics Data System (ADS)

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

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

2002-05-01

382

Proton Therapy Coverage for Prostate Cancer Treatment  

SciTech Connect

Purpose: To determine the impact of prostate motion on dose coverage in proton therapy. Methods and Materials: A total of 120 prostate positions were analyzed on 10 treatment plans for 10 prostate patients treated using our low-risk proton therapy prostate protocol (University of Florida Proton Therapy Institute 001). Computed tomography and magnetic resonance imaging T{sub 2}-weighted turbo spin-echo scans were registered for all cases. The planning target volume included the prostate with a 5-mm axial and 8-mm superoinferior expansion. The prostate was repositioned using 5- and 10-mm one-dimensional vectors and 10-mm multidimensional vectors (Points A-D). The beam was realigned for the 5- and 10-mm displacements. The prescription dose was 78 Gy equivalent (GE). Results: The mean percentage of rectum receiving 70 Gy (V{sub 70}) was 7.9%, the bladder V{sub 70} was 14.0%, and the femoral head/neck V{sub 50} was 0.1%, and the mean pelvic dose was 4.6 GE. The percentage of prostate receiving 78 Gy (V{sub 78}) with the 5-mm movements changed by -0.2% (range, 0.006-0.5%, p > 0.7). However, the prostate V{sub 78} after a 10-mm displacement changed significantly (p < 0.003) with different movements: 3.4% (superior), -5.6% (inferior), and -10.2% (posterior). The corresponding minimal doses were also reduced: 4.5 GE, -4.7 GE, and -11.7 GE (p {<=} 0.003). For displacement points A-D, the clinical target volume V{sub 78} coverage had a large and significant reduction of 17.4% (range, 13.5-17.4%, p < 0.001) in V{sub 78} coverage of the clinical target volume. The minimal prostate dose was reduced 33% (25.8 GE), on average, for Points A-D. The prostate minimal dose improved from 69.3 GE to 78.2 GE (p < 0.001) with realignment for 10-mm movements. Conclusion: The good dose coverage and low normal doses achieved for the initial plan was maintained with movements of {<=}5 mm. Beam realignment improved coverage for 10-mm displacements.

Vargas, Carlos [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States)], E-mail: c2002@ufl.edu; Wagner, Marcus; Mahajan, Chaitali [University of Florida Proton Therapy Institute, Jacksonville, FL (United States); Indelicato, Daniel [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Fryer, Amber; Falchook, Aaron; Horne, David C.; Chellini, Angela; McKenzie, Craig C.; Lawlor, Paula C.; Li Zuofeng; Lin Liyong; Keole, Sameer [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

2008-04-01

383

Proton-proton diffractive collisions at ultrahigh energies  

NASA Astrophysics Data System (ADS)

Proton-proton total and elastic cross sections are considered in the Dakhno-Nikonov eikonal model [L. G. Dakhno and V. A. Nikonov, Eur. Phys. J. A 8, 209 (1999)] at ultrahigh energies. The model takes into account the quark structure of hadrons and the gluon structure of the supercritical Pomeron that results in color screening. The Pomeron is considered as an input interaction term. The model gives a reasonably good description of the pre-LHC and LHC data for pp collisions with a growth of the type ln?2s for total and elastic cross sections and (?=q?2ln?2s) scaling for diffractive scattering. We present parameters of the supercritical Pomeron and provide predictions for the energy region s˜102-104TeV.

Anisovich, V. V.; Nikonov, K. V.; Nikonov, V. A.

2013-07-01

384

Proton-proton elastic scattering excitation functions at intermediate energies  

NASA Astrophysics Data System (ADS)

Polarized and unpolarized proton-proton elastic scattering is investigated with the EDDA-experiment at the Cooler Synchrotron COSY at Jülich to significantly improve the world data base in the beam energy range 500-2500 MeV. Measurements during beam acceleration with thin internal targets and a large acceptance detector provide excitation functions over a broad angular and energy range with unprecedented internal consistency. Data taking with an unpolarized CH2 fiber target and an unpolarized beam have been completed and the derived differential cross sections are presented and compared to a recent phase shift analysis. With a polarized atomic beam target newly installed in COSY and a polarized COSY beam-currently under development-the measurements will be extended to analyzing powers and spin correlation parameters.

Rohdjess, H.

1998-05-01

385

ACCELERATION OF POLARIZED PROTONS AT RHIC.  

SciTech Connect

Relativistic Heavy Ion Collider (RHIC) ended its second year of operation in January 2002 with five weeks of polarized proton collisions. Polarized protons were successfully injected in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. This is the first time that polarized protons have been accelerated to 100 GeV. The machine performance and accomplishments during the polarized proton run will be reviewed. The plans for the next polarized proton run will be outlined.

HUANG,H.

2002-09-09

386

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

387

Proton-nuclear magnetic resonance relaxation times in brain edema  

SciTech Connect

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

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

1990-01-01

388

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

389

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

390

Proton-proton weak capture in chiral effective field theory.  

PubMed

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(-23) MeV fm(2), with a P-wave contribution of 0.020×10(-23) MeV fm(2). The theoretical uncertainty is due to the fitting procedure of the low-energy constants and to the cutoff dependence. PMID:23705703

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

2013-05-10

391

Direct Observation of Two Proton Radioactivity Using Digital Photography  

SciTech Connect

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

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

2007-01-01

392

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

393

Subsecond Proton-Hole Propagation in Bacteriorhodopsin  

PubMed Central

The dynamics of proton transfer between the surface of purple membrane and the aqueous bulk have recently been investigated by the Laser Induced Proton Pulse Method. Following a ?-function release of protons to the bulk, the system was seen to regain its state of equilibrium within a few hundreds of microseconds. These measurements set the time frame for the relaxation of any state of acid-base disequilibrium between the bacteriorhodopsin's surface and the bulk. It was also deduced that the released protons react with the various proton binding within less than 10 ?s. In the present study, we monitored the photocycle and the proton-cycle of photo-excited bacteriorhodopsin, in the absence of added buffer, and calculated the proton balance between the Schiff base and the bulk phase in a time-resolved mode. It was noticed that the late phase of the M decay (beyond 1 ms) is characterized by a slow (subsecond) relaxation of disequilibrium, where the Schiff base is already reprotonated but the pyranine still retains protons. Thus, it appears that the protonation of D96 is a slow rate-limiting process that generates a “proton hole” in the cytoplasmic section of the protein. The velocity of the hole propagation is modulated by the ionic strength of the solution and by selective replacements of charged residues on the interhelical loops of the protein, at domains that seems to be remote from the intraprotein proton conduction trajectory.

Schatzler, Bettina; Dencher, Norbert A.; Tittor, Joerg; Oesterhelt, Dieter; Yaniv-Checover, Sharon; Nachliel, Esther; Gutman, Menachem

2003-01-01

394

Proton-rich Nuclear Statistical Equilibrium  

NASA Astrophysics Data System (ADS)

Proton-rich material in a state of nuclear statistical equilibrium (NSE) is one of the least studied regimes of nucleosynthesis. One reason for this is that after hydrogen burning, stellar evolution proceeds at conditions of an equal number of neutrons and protons or at a slight degree of neutron-richness. Proton-rich nucleosynthesis in stars tends to occur only when hydrogen-rich material that accretes onto a white dwarf or a neutron star explodes, or when neutrino interactions in the winds from a nascent proto-neutron star or collapsar disk drive the matter proton-rich prior to or during the nucleosynthesis. In this Letter we solve the NSE equations for a range of proton-rich thermodynamic conditions. We show that cold proton-rich NSE is qualitatively different from neutron-rich NSE. Instead of being dominated by the Fe-peak nuclei with the largest binding energy per nucleon that have a proton-to-nucleon ratio close to the prescribed electron fraction, NSE for proton-rich material near freezeout temperature is mainly composed of 56Ni and free protons. Previous results of nuclear reaction network calculations rely on this nonintuitive high-proton abundance, which this Letter explains. We show how the differences and especially the large fraction of free protons arises from the minimization of the free energy as a result of a delicate competition between the entropy and nuclear binding energy.

Seitenzahl, I. R.; Timmes, F. X.; Marin-Laflèche, A.; Brown, E.; Magkotsios, G.; Truran, J.

2008-10-01

395

First Observation of Beta-Delayed Three-Proton Emission in 45Fe  

SciTech Connect

The decay of extremely neutron deficient 45Fe has been studied by means of a new type of a gaseous detector in which a technique of digital imaging was used to record tracks of charged particles. The + decay channels accompanied by proton emission were clearly identified. In addition to -delayed one-proton and -delayed two-proton decays, -delayed three-proton emission was recorded which represents the first direct and unambiguous observation of this decay channel. The branching ratio for the decay of 45Fe and the corresponding partial half-life are found to be 0.30 0.04 and T1/2( ) = 8.7 1.3 ms, respectively.

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

2007-01-01

396

First observation of {beta}-delayed three-proton emission in {sup 45}Fe  

SciTech Connect

The decay of extremely neutron deficient {sup 45}Fe has been studied by means of a new type of a gaseous detector in which a technique of digital imaging was used to record tracks of charged particles. The {beta}{sup +} decay channels accompanied by proton emission were clearly identified. In addition to {beta}-delayed one-proton and {beta}-delayed two-proton decays, {beta}-delayed three-proton emission was recorded which represents the first direct and unambiguous observation of this decay channel. The branching ratio for the {beta} decay of {sup 45}Fe and the corresponding partial half-life are found to be 0.30{+-}0.04 and T{sub 1/2}({beta})=8.7{+-}1.3 ms, respectively.

Miernik, K.; Dominik, W.; Janas, Z.; Pfuetzner, M.; Czyrkowski, H.; Cwiok, M.; DaPbrowski, R.; Karny, M.; Korgul, A.; Kusmierz, W. [Institute of Experimental Physics, Warsaw University, PL-00-681 Warsaw (Poland); Bingham, C. R.; Darby, I. G.; Liddick, S. N.; Rajabali, M. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Ginter, T.; Stolz, A. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); 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); Rykaczewski, K. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2007-10-15

397

Laser generated proton beam focusing and high temperature isochoric heating of solid matter  

SciTech Connect

The results of laser-driven proton beam focusing and heating with a high energy (170 J) short pulse are reported. Thin hemispherical aluminum shells are illuminated with the Gekko petawatt laser using 1 {mu}m light at intensities of {approx}3x10{sup 18} W/cm{sup 2} and measured heating of thin Al slabs. The heating pattern is inferred by imaging visible and extreme-ultraviolet light Planckian emission from the rear surface. When Al slabs 100 {mu}m thick were placed at distances spanning the proton focus beam waist, the highest temperatures were produced at 0.94x the hemisphere radius beyond the equatorial plane. Isochoric heating temperatures reached 81 eV in 15 {mu}m thick foils. The heating with a three-dimensional Monte Carlo model of proton transport with self-consistent heating and proton stopping in hot plasma was modeled.

Snavely, R. A.; Hatchett, S. P.; Key, M. H.; Langdon, A. B.; Lasinski, B. F.; MacKinnon, A. J.; Patel, P.; Town, R.; Wilks, S. C. [University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 14550 (United States); Zhang, B.; Akli, K.; Hey, D.; King, J. [University of California, Davis, Department of Applied Science, P.O. Box 808, L714, Livermore, California 94552 (United States); Chen, Z.; Izawa, Y.; Kitagawa, Y.; Kodama, R.; Lei, A.; Tampo, M.; Tanaka, K. A. [Institute of Laser Energetics, Osaka University, Suita, Osaka 565 (Japan)] (and others)

2007-09-15

398

First observation of ?-delayed three-proton emission in Fe45  

NASA Astrophysics Data System (ADS)

The decay of extremely neutron deficient Fe45 has been studied by means of a new type of a gaseous detector in which a technique of digital imaging was used to record tracks of charged particles. The ?+ decay channels accompanied by proton emission were clearly identified. In addition to ?-delayed one-proton and ?-delayed two-proton decays, ?-delayed three-proton emission was recorded which represents the first direct and unambiguous observation of this decay channel. The branching ratio for the ? decay of Fe45 and the corresponding partial half-life are found to be 0.30±0.04 and T1/2(?)=8.7±1.3 ms, respectively.

Miernik, K.; Dominik, W.; Janas, Z.; Pfützner, M.; Bingham, C. R.; Czyrkowski, H.; ?wiok, M.; Darby, I. G.; D?browski, R.; Ginter, T.; Grzywacz, R.; Karny, M.; Korgul, A.; Ku?mierz, W.; Liddick, S. N.; Rajabali, M.; Rykaczewski, K.; Stolz, A.

2007-10-01

399

Proton radiation damage study of the next generation of swept charge devices  

NASA Astrophysics Data System (ADS)

The first generation of Swept Charge Device (SCD) the e2v technologies plc CCD54 was used in the Demonstration of a Compact Imaging X-ray Spectrometer (D-CIXS) launched in 2003 and again in the Chandrayaan-1 X-ray Spectrometer (C1XS) instrument currently in orbit around the Moon. The main source of decreased energy resolution in both cases is proton damage, from trapped and solar protons respectively. This paper presents the results from an experimental study to evaluate the performance of the next generation of SCD the CCD234 and CCD236 irradiated with a 10 MeV equivalent proton fluence of 3.0×108 protons.cm-2 demonstrating the factor of two increase in radiation hardness when compared to the CCD54. In particular the increased leakage current, decrease in energy resolution and the degradation of charge transfer efficiency (CTE) are described.

Gow, J.; Holland, A. D.; Pool, P.

2009-08-01

400

Neutron imaging camera  

NASA Astrophysics Data System (ADS)

The Neutron Imaging Camera (NIC) is based on the Three-dimensional Track Imager (3_DTI) technology developed at GSFC for gamma-ray astrophysics applications. The 3-DTI, a large volume time-projection chamber, provides accurate, ~0.4 mm resolution, 3-D tracking of charged particles. The incident direction of fast neutrons, En > 0.5 MeV, are reconstructed from the momenta and energies of the proton and triton fragments resulting from 3He(n,p)3H interactions in the 3-DTI volume. The performance of the NIC from laboratory is presented.

Hunter, S. D.; de Nolfo, G. A.; Barbier, L. M.; Link, J. T.; Son, S.; Floyd, S. R.; Guardala, N.; Skopec, M.; Stark, B.

2008-05-01