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1

Proton Density-Weighted Functional Magnetic Resonance Imaging at 0.35 Tesla  

Microsoft Academic Search

Functional magnetic resonance imaging of healthy human volunteers was carried out at 0.35T MRI system, using proton-density weighted turbo spin-echo imaging. It aims at verifying the proton-density change contribution to spin-echo functional magnetic resonance imaging. And try to get better effect of fMRI studies at 0.35T MRI system. Results demonstrated that signal intensity changes in motor area of the brain

Ping. Yang; Jinxing. Wang; Yuesheng Chao; Guang Lu; Jinquan Shi

2008-01-01

2

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

PubMed Central

Functional magnetic resonance imaging (fMRI) has become a powerful and influential method to non-invasively study neuronal brain activity. For this purpose, the blood oxygenation level-dependent (BOLD) effect is most widely used. T2* weighted echo planar imaging (EPI) is BOLD sensitive and the prevailing fMRI acquisition technique. Here, we present an alternative to its standard Cartesian recordings, i.e. k-space density weighted EPI, which is expected to increase the signal-to-noise ratio in fMRI data. Based on in vitro and in vivo pilot measurements, we show that fMRI by k-space density weighted EPI is feasible and that this new acquisition technique in fact boosted spatial and temporal SNR as well as the detection of local fMRI activations. Spatial resolution, spatial response function and echo time were identical for density weighted and conventional Cartesian EPI. The signal-to-noise ratio gain of density weighting can improve activation detection and has the potential to further increase the sensitivity of fMRI investigations. PMID:24040262

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

2013-01-01

3

MRI of the anatomical structures of the knee: the proton density-weighted fast spin-echo sequence vs the proton density-weighted fast-recovery fast spin-echo sequence  

PubMed Central

Objective The purpose of this study was to compare the proton-density (PD)-weighted fast spin-echo (FSE) and fast-recovery FSE (FRFSE) sequences for the evaluation of the anatomical structures of the knee. Method 24 healthy volunteers who underwent MRI by both sagittal PD-weighted FSE and FRFSE sequences were evaluated. The signal-to-noise ratio, contrast-to-noise ratio (CNR) and anatomical detail visualisation were compared for the two techniques. Results The mean CNRs and reader ratings for both readers were significantly higher for the PD-weighted FRFSE images than for the PD-weighted FSE images in the cartilages/the femorotibial joint effusion and the cruciate ligaments/the effusion around the cruciate ligaments; however, the mean CNRs and reader ratings for both readers were significantly higher for the PD-weighted FSE sequences than for the PD-weighted FRFSE sequences in the cartilages/the menisci and the cruciate ligaments. Conclusions The main advantages of the PD-weighted FRFSE sequence are the increase in contrast between fluid and non-fluid tissues and the time saved by using the procedure. However, in the absence of joint effusion, the PD-weighted FRFSE sequence generates a poorer contrast between the cartilage and meniscus, the cruciate ligaments and fat of the intercondylar fossa. PMID:22215886

Tokuda, O; Harada, Y; Shiraishi, G; Motomura, T; Fukuda, K; Kimura, M; Matsunaga, N

2012-01-01

4

Comparison of optical imaging and functional magnetic resonance imaging of the human brain using a photon-hitting density weight in the calculation of the BOLD signal  

NASA Astrophysics Data System (ADS)

We present a new method for the calculation of a blood oxygen level dependent (BOLD) signal which is meaningful for a quantitative comparison with near infrared spectroscopy (NIRS) data. Since optical tomography of the human brain still poses several difficulties, in this study we propose a way to project the BOLD signal on a two-dimensional (2D) map for comparison with NIRS data. The underlying assumption is that fMRI and NIRS are sensitive to similar aspects of the hemodynamic changes occurring during a functional task, and therefore they should have similar spatial and temporal features. We present a case study of functional activation during a finger-tapping test where we used the new method for the calculation of BOLD signal. For every optical source-detector pair we calculated a weighted BOLD signal by using a photon hitting-density weight function, and by using a simple back-projection algorithm we were able to generate BOLD 2D maps. We found that the weighted BOLD signals calculated from different source-detector pairs scale in a similar way to the corresponding oxy and deoxy-hemeoglobin concentration changes calculated from NIRS data, for most of the time range of the task. Therefore the BOLD 2D maps were quantitatively similar to the optical maps calculated at different times during the protocol.

Sassaroli, Angelo; Frederick, Blaise B.; Tong, Yunjie; Renshaw, Perry F.; Fantini, Sergio

2006-02-01

5

Proton Therapy Verification with PET Imaging  

PubMed Central

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

Zhu, Xuping; Fakhri, Georges El

2013-01-01

6

Metabolite specific proton magnetic resonance imaging.  

PubMed Central

An imaging method is described that makes use of proton double quantum nuclear magnetic resonance (NMR) to construct images based on selected metabolites such as lactic acid. The optimization of the method is illustrated in vitro, followed by in vivo determination of lactic acid distribution in a solid tumor model. Water suppression and editing of lipid signals are such that two-dimensional spectra of lactic acid may be obtained from a radiation-induced fibrosarcoma (RIF-1) tumor in under 1 min and lactic acid images from the same tumor in under 1 hr at 2.0 T. This technique provides a fast and reproducible method at moderate magnetic field strength for mapping biologically relevant metabolites. Images PMID:2734292

Hurd, R E; Freeman, D M

1989-01-01

7

Spectral imaging of proton aurora and twilight at Troms, Norway  

E-print Network

Spectral imaging of proton aurora and twilight at Tromsø, Norway M. Galand,1 J. Baumgardner,1 D, which offers a unique opportunity to investigate the Ha to Hb Balmer decrement in proton aurora locations (Tromsø, Poker Flat, Svalbard) in proton aurora is presented. Lummerzheim and Galand [2001] find

Lummerzheim, Dirk

8

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

E-print Network

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

California at Berkeley, University of

9

Proton magnetic resonance imaging of lipid in pecan embryos  

Microsoft Academic Search

Magnetic resonance images of plant tissues typically are manifestations of water protons in tissues. Within oilseeds, however,\\u000a lipids contain a major portion of the mobile protons, which should enable specific imaging of lipids. In this study, experiments\\u000a were done to demonstrate spin-echo imaging (SEI) and chemical-shift imaging (CSI) of lipid within nonimbibed and imbibed embryos\\u000a of pecan (Carya illinoensis), a

John M. Halloina; Thomas G. Cooper; E. James Potchen; Tommy E. Thompson

1993-01-01

10

Modeling and optimization of a time-resolved proton radiographic imaging system for proton cancer treatment  

NASA Astrophysics Data System (ADS)

This dissertation describes a research project to test the clinical utility of a time-resolved proton radiographic (TRPR) imaging system by performing comprehensive Monte Carlo simulations of a physical device coupled with realistic lung cancer patient anatomy defined by 4DCT for proton therapy. A time-resolved proton radiographic imaging system was modeled through Monte Carlo simulations. A particle-tracking feature was employed to evaluate the performance of the proton imaging system, especially in its ability to visualize and quantify proton range variations during respiration. The Most Likely Path (MLP) algorithm was developed to approximate the multiple Coulomb scattering paths of protons for the purpose of image reconstruction. Spatial resolution of ˜ 1 mm and range resolution of 1.3% of the total range were achieved using the MLP algorithm. Time-resolved proton radiographs of five patient cases were reconstructed to track tumor motion and to calculate water equivalent length variations. By comparing with direct 4DCT measurement, the accuracy of tumor tracking was found to be better than 2 mm in five patient cases. Utilizing tumor tracking information to reduce margins to the planning target volume, a gated treatment plan was compared with un-gated treatment plan. The equivalent uniform dose (EUD) and the normal tissue complication probability (NTCP) were used to quantify the gain in the quality of treatments. The EUD of the OARs was found to be reduced up to 11% and the corresponding NTCP of organs at risk (OARs) was found to be reduced up to 16.5%. These results suggest that, with image guidance by proton radiography, dose to OARs can be reduced and the corresponding NTCPs can be significantly reduced. The study concludes that the proton imaging system can accurately track the motion of the tumor and detect the WEL variations, leading to potential gains in using image-guided proton radiography for lung cancer treatments.

Han, Bin

11

Total variation superiorization schemes in proton computed tomography image reconstruction  

E-print Network

CT) has been suggested as a means for reducing the range40 uncertainty in proton radiation therapy11 Total variation superiorization schemes in proton computed tomography image reconstruction S. N. Penfolda Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia5 R. W

Censor, Yair

12

Improved proton computed tomography by dual modality image reconstruction  

SciTech Connect

Purpose: Proton computed tomography (CT) is a promising image modality for improving the stopping power estimates and dose calculations for particle therapy. However, the finite range of about 33 cm of water of most commercial proton therapy systems limits the sites that can be scanned from a full 360° rotation. In this paper the authors propose a method to overcome the problem using a dual modality reconstruction (DMR) combining the proton data with a cone-beam x-ray prior. Methods: A Catphan 600 phantom was scanned using a cone beam x-ray CT scanner. A digital replica of the phantom was created in the Monte Carlo code Geant4 and a 360° proton CT scan was simulated, storing the entrance and exit position and momentum vector of every proton. Proton CT images were reconstructed using a varying number of angles from the scan. The proton CT images were reconstructed using a constrained nonlinear conjugate gradient algorithm, minimizing total variation and the x-ray CT prior while remaining consistent with the proton projection data. The proton histories were reconstructed along curved cubic-spline paths. Results: The spatial resolution of the cone beam CT prior was retained for the fully sampled case and the 90° interval case, with the MTF = 0.5 (modulation transfer function) ranging from 5.22 to 5.65?linepairs/cm. In the 45° interval case, the MTF = 0.5 dropped to 3.91?linepairs/cm For the fully sampled DMR, the maximal root mean square (RMS) error was 0.006 in units of relative stopping power. For the limited angle cases the maximal RMS error was 0.18, an almost five-fold improvement over the cone beam CT estimate. Conclusions: Dual modality reconstruction yields the high spatial resolution of cone beam x-ray CT while maintaining the improved stopping power estimation of proton CT. In the case of limited angles, the use of prior image proton CT greatly improves the resolution and stopping power estimate, but does not fully achieve the quality of a 360° proton CT scan.

Hansen, David C., E-mail: dch@ki.au.dk; Bassler, Niels [Experimental Clinical Oncology, Aarhus University, 8000 Aarhus C (Denmark)] [Experimental Clinical Oncology, Aarhus University, 8000 Aarhus C (Denmark); Petersen, Jørgen Breede Baltzer [Medical Physics, Aarhus University Hospital, 8000 Aarhus C (Denmark)] [Medical Physics, Aarhus University Hospital, 8000 Aarhus C (Denmark); Sørensen, Thomas Sangild [Computer Science, Aarhus University, 8000 Aarhus C, Denmark and Clinical Medicine, Aarhus University, 8200 Aarhus N (Denmark)] [Computer Science, Aarhus University, 8000 Aarhus C, Denmark and Clinical Medicine, Aarhus University, 8200 Aarhus N (Denmark)

2014-03-15

13

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

14

Imaging of Plasma Focus Fusion by Proton Coded Aperture Technique  

NASA Astrophysics Data System (ADS)

The coded aperture imaging (CAI) technique has been applied to investigate the spatial distribution of DD fusion in a deuterium filled 1.6 kJ plasma focus (PF) device operated in its neutron-optimized regime. The coded mask has been fabricated in Havar alloy with 20 × 20 pixels and 57 square holes (14% open area) using a Singer-set Cyclic Difference pattern. Five CAI cameras were employed simultaneously: one placed on-axis (0°) and four at 45° to the PF axis. CR-39 polymer nuclear track detectors were used to register proton tracks from D(d,p)T reactions. The detectors were covered by 75 ?m Kapton film to stop all energetic charged particles (mostly deuterons) other than the 3 MeV fusion protons. A de-convolution algorithm was applied to the measured proton track coordinates to obtain images of the fusion source from the five directions. Typically (2-8) × 104 proton tracks were registered by each detector per shot. Also two beryllium fast-neutron detectors were employed simultaneously to measure the associated neutron yield and anisotropy. The CAI images show the fusion source is a cigar-shaped region around the pinch column with no indication of plasma column instabilities. The proton anisotropy is comparable to the measured neutron anisotropy.

Talebitaher, Alireza; Springham, Stuart Victor; Shutler, Paul Maurice Edmund; Lee, Paul; Rawat, Rajdeep Singh

2012-06-01

15

Functional magnetic resonance imaging at 0.2 Tesla  

Microsoft Academic Search

Functional magnetic resonance imaging of healthy human volunteers was carried out at 0.2 T, using proton-density weighted (TE = 24 ms) spin-echo imaging, in order to eliminate any contribution from the blood oxygenation-level dependent (BOLD) effect. The purpose of the study was to verify the existence of a proton-density change contribution to spin-echo functional magnetic resonance imaging (fMRI) data. Results

P. W Stroman; K. L Malisza; M Onu

2003-01-01

16

Fabrication of fine imaging devices using an external proton microbeam  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

17

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

E-print Network

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

California at Berkeley, University of

18

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

19

Characteristics of Proton CT Images Reconstructed with Filtered Backprojection and Iterative Projection  

E-print Network

. With the expansion of proton therapy over the last decade, interest has again been placed in pCT. Now, pCT is being developed as a means for maximizing the potential benefits of proton therapy. The pCT design proposedCharacteristics of Proton CT Images Reconstructed with Filtered Backprojection and Iterative

Censor, Yair

20

Noise evaluation of Compton camera imaging for proton therapy.  

PubMed

Compton Cameras emerged as an alternative for real-time dose monitoring techniques for Particle Therapy (PT), based on the detection of prompt-gammas. As a consequence of the Compton scattering process, the gamma origin point can be restricted onto the surface of a cone (Compton cone). Through image reconstruction techniques, the distribution of the gamma emitters can be estimated, using cone-surfaces backprojections of the Compton cones through the image space, along with more sophisticated statistical methods to improve the image quality. To calculate the Compton cone required for image reconstruction, either two interactions, the last being photoelectric absorption, or three scatter interactions are needed. Because of the high energy of the photons in PT the first option might not be adequate, as the photon is not absorbed in general. However, the second option is less efficient. That is the reason to resort to spectral reconstructions, where the incoming ? energy is considered as a variable in the reconstruction inverse problem. Jointly with prompt gamma, secondary neutrons and scattered photons, not strongly correlated with the dose map, can also reach the imaging detector and produce false events. These events deteriorate the image quality. Also, high intensity beams can produce particle accumulation in the camera, which lead to an increase of random coincidences, meaning events which gather measurements from different incoming particles. The noise scenario is expected to be different if double or triple events are used, and consequently, the reconstructed images can be affected differently by spurious data. The aim of the present work is to study the effect of false events in the reconstructed image, evaluating their impact in the determination of the beam particle ranges. A simulation study that includes misidentified events (neutrons and random coincidences) in the final image of a Compton Telescope for PT monitoring is presented. The complete chain of detection, from the beam particle entering a phantom to the event classification, is simulated using FLUKA. The range determination is later estimated from the reconstructed image obtained from a two and three-event algorithm based on Maximum Likelihood Expectation Maximization. The neutron background and random coincidences due to a therapeutic-like time structure are analyzed for mono-energetic proton beams. The time structure of the beam is included in the simulations, which will affect the rate of particles entering the detector. PMID:25658644

Ortega, P G; Torres-Espallardo, I; Cerutti, F; Ferrari, A; Gillam, J E; Lacasta, C; Llosá, G; Oliver, J F; Sala, P R; Solevi, P; Rafecas, M

2015-02-21

21

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

E-print Network

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

DeCiantis, Joseph Loreto

2005-01-01

22

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

23

Monitoring proton radiation therapy with in-room PET imaging  

PubMed Central

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

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

2011-01-01

24

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

E-print Network

-guided diagnosis and radiation therapy. For diagnosis, the fact that the patient dose committed by proton CT imaging method to perform planning and verification of proton-based radiation treatment, since proton the most appropriate imaging method to perform planning and verification of proton-based radiation

California at Santa Cruz, University of

25

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

26

Patient positioning method based on binary image correlation between two edge images for proton-beam radiation therapy  

Microsoft Academic Search

A new technique based on normalized binary image correlation between two edge images has been proposed for positioning proton-beam radiotherapy patients. A Canny edge detector was used to extract two edge images from a reference x-ray image and a test x-ray image of a patient before positioning. While translating and rotating the edged test image, the absolute value of the

Akira Sawada; Kiyoshi Yoda; Masumi Numano; Yasuyuki Futami; Haruo Yamashita; Shigeyuki Murayama; Hironobu Tsugami

2005-01-01

27

In vivo proton nuclear magnetic resonance imaging and spectroscopy studies of halocarbon-induced liver damage.  

PubMed

Proton magnetic resonance imaging and localized NMR spectroscopy were used to study the rat liver in situ. Respiratory gating was used in both the imaging and the localized spectroscopy studies to control for the movement of the upper abdomen of the rat during breathing. After administration of carbon tetrachloride, bromotrichloromethane, or halothane, localized regions of high proton signal intensity were observed in the NMR images of the liver. Localized (VOSY) proton NMR spectra from within these regions indicated that the increase in a signal intensity was due to a longer T2 relaxation time for the water resonance, indicating acute edema in the region of tissue damage. PMID:2541304

Brauer, M; Towner, R A; Renaud, I; Janzen, E G; Foxall, D L

1989-02-01

28

Science to Practice: Highly Shifted Proton MR imaging—A Shift toward Better Cell Tracking?  

PubMed Central

Summary A “hot spot” magnetic resonance (MR) imaging cell tracking technique has been developed that allows direct detection of dysprosium- or thulium-1,4,7,10-tetraazacyclododecane-?,??,??,??-tetramethyl-1,4,7,10-tetraacetic acid (DOTMA)–labeled protons inside cells. These highly shifted protons may allow specific detection of multiple cell types because it does not rely on acquiring the proton signal from bulk water. PMID:25153271

Bulte, Jeff W. M.

2015-01-01

29

Fine phantom image from laser-induced proton radiography with a spatial resolution of several ?m  

NASA Astrophysics Data System (ADS)

The advantages of a laser-driven proton acceleration have prompted studies of laser-induced proton radiography. As the CR-39 solid-state nuclear-track detector is suitable for measuring charged particles and can be used in proton radiography, we studied laser-induced proton radiography with the CR-39 for several years, and we were able to obtain a spatial resolution of about 10 ?m. For obtaining an image with a spatial resolution of a few ?m, we investigated the effect of the CR-39 etching conditions on the spatial resolution and carried out imaging experiments using fine phantoms. Experiments were performed using the 100-TW titanium-sapphire laser system at the Advanced Photonics Research Institute of the Gwangju Institute of Science Technology. We have demonstrated that images with a spatial resolution of about several ?m can be achieved using laser-induced proton radiography.

Son, Jaebum; Lee, Cheol Ho; Kang, Jeongsoo; Jang, Doh-Yun; Park, Junesic; Kim, Yun Ho; Kim, Yong Kyun; Choi, Chang Il; Kim, I. Jong; Choi, Il Woo; Sung, Jae Hee; Lee, Seong Ku; Jeong, Tae Moon; Lee, Chang-Lyoul; Yu, Tae Jun; Lee, Jongmin

2014-07-01

30

Fatty infiltration of the liver: demonstration by proton spectroscopic imaging: preliminary observations  

SciTech Connect

Two normal volunteers and three patients with CT evidence of fatty infiltration of the liver were studied to determine whether magnetic resonance imaging using a pulse sequence designed to differentiate fat and water could be used to detect fatty infiltration of the liver in human being. The magnetic resonance technique used a modified spin echo technique (simple proton spectroscopic imaging). Quantitative data showed that fatty liver can be separated from normal liver using the spin echo technique, and that the opposed image of the proton spectroscopic technique is more sensitive to small changes in hepatic fatty content than in-phase images with any echo time.

Lee, J.K.T.; Dixon, W.T.; Ling, D.; Levitt, R.G.; Murphy, W.A. Jr.

1984-10-01

31

Contribution of thin-slice (1 mm) axial proton density MR images for identification and classification of meniscal tears: correlative study with arthroscopy  

PubMed Central

Objective To evaluate the diagnostic efficacy of thin-slice (1 mm) axial proton density-weighted (PDW) MRI of the knee for meniscal tear detection and classification. Methods We prospectively assessed pre-operative MR images of 58 patients (41 males, 17 females; age range 18–62 years) with arthroscopically confirmed meniscal tear. First, we evaluated the performance of the sagittal and thin-slice axial MR images for the diagnosis of meniscal tears. Second, we compared the correlation of tear types presumed from sagittal and axial MRI with arthroscopy and tear classification from axial MRI. Tears were classified on the sagittal plane and the axial plane separately. The diagnostic performance and tear classification were compared statistically with arthroscopy results, which is accepted as the standard of reference. Results 8 of 58 patients were removed from the study group because they had complex or degenerative tears. A total of 62 tears were detected with arthroscopy in 50 patients. On the sagittal images, sensitivity and specificity values were 90.62% and 70.37%, respectively, for medial meniscus tears and 72.73% and 77.14%, respectively, for lateral meniscus tears. The corresponding values for axial images were 97.30% and 84.00%, respectively, for medial meniscus tears and 95.65% and 80.50%, respectively, for lateral meniscus tears. There was no significant difference in tear classification between the arthroscopy results and the thin-slice axial PDW MRI results (p>0.05). Conclusion thin-slice axial PDW MRI increases the sensitivity and specificity of meniscal tear detection and especially classification, which is important for surgical procedure decisions. PMID:22553302

Gökalp, G; Nas, O F; Demirag, B; Yazici, Z; Savci, G

2012-01-01

32

A proton Computed Tomography based medical imaging system  

NASA Astrophysics Data System (ADS)

This paper reports on the activity of the INFN PRIMA/RDH collaboration in the development of proton Computed Tomography (pCT) systems based on single proton tracking and residual energy measurement. The systems are made of a silicon microstrip tracker and a YAG:Ce crystal calorimeter to measure single protons trajectory and residual energy, respectively. A first prototype of pCT scanner, with an active area of about 5 × 5 cm2 and a data rate capability of 10 kHz, has been constructed and characterized with 62 MeV protons at INFN Laboratori Nazionali del Sud in Catania (Italy) and with 180 MeV protons at The Svedberg Laboratory (TSL) in Uppsala (Sweden). Results of these measurements, including tomographic reconstructions of test phantoms, will be shown and discussed. An upgraded system with an extended field of view (up to ~ 5 × 20 cm2) and an increased event rate capability up to one MHz, presently under development, will be also described.

Scaringella, M.; 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.; Sipala, V.; Stancampiano, C.; Talamonti, C.; Vanzi, E.; Zani, M.

2014-12-01

33

Multiscale X-ray and Proton Imaging of Bismuth-Tin Solidification  

NASA Astrophysics Data System (ADS)

The formation of structural patterns during metallic solidification is complex and multiscale in nature, ranging from the nanometer scale, where solid-liquid interface properties are important, to the macroscale, where casting mold filling and intended heat transfer are crucial. X-ray and proton imaging can directly interrogate structure, solute, and fluid flow development in metals from the microscale to the macroscale. X-rays permit high spatio-temporal resolution imaging of microscopic solidification dynamics in thin metal sections. Similarly, high-energy protons permit imaging of mesoscopic and macroscopic solidification dynamics in large sample volumes. In this article, we highlight multiscale x-ray and proton imaging of bismuth-tin alloy solidification to illustrate dynamic measurement of crystal growth rates and solute segregation profiles that can be that can be acquired using these techniques.

Gibbs, P. J.; Imhoff, S. D.; Morris, C. L.; Merrill, F. E.; Wilde, C. H.; Nedrow, P.; Mariam, F. G.; Fezzaa, K.; Lee, W.-K.; Clarke, A. J.

2014-08-01

34

Imaging of Fusion Protons from a 3 kJ Deuterium Plasma Focus  

Microsoft Academic Search

This paper reports a study of the proton emission from a 3 kJ, 14 kV plasma focus device operated with deuterium gas at 400 Pa. A filtered pinhole camera with a 1.8 mm diameter hole is placed axially downstream of the plasma focus, and images of the proton-emitting region are recorded using CR-39\\/PM-355 nuclear track detectors. The detector plates are

Stuart Victor Springham; Siew Pheng Moo; Paul Lee; Rajdeep Singh Rawat; Alin Constantin Patran; Sing Lee

2005-01-01

35

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

Microsoft Academic Search

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

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

2003-01-01

36

A knowledge-based imaging informatics approach to managing patients treated with proton beam therapy  

Microsoft Academic Search

Last year we presented work on an imaging informatics approach towards developing quantitative knowledge and tools based on standardized DICOM-RT objects for Image-Guided Radiation Therapy. In this paper, we have extended this methodology to perform knowledge-based medical imaging informatics research on specific clinical scenarios where brain tumor patients are treated with Proton Beam Therapy (PT). PT utilizes energized charged particles,

B. J. Liu; H. K. Huang; M. Law; Anh Le; Jorge Documet; Arek Gertych

2007-01-01

37

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

38

Transverse Imaging of the Proton in Exclusive Diffractive pp Scattering  

SciTech Connect

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

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

2006-04-20

39

Imaging of Fusion Protons from a 3 kJ Deuterium Plasma Focus  

NASA Astrophysics Data System (ADS)

This paper reports a study of the proton emission from a 3 kJ, 14 kV plasma focus device operated with deuterium gas at 400 Pa. A filtered pinhole camera with a 1.8 mm diameter hole is placed axially downstream of the plasma focus, and images of the proton-emitting region are recorded using CR-39/PM-355 nuclear track detectors. The detector plates are scanned using an automated track measurement system and the spatial track density profile is acquired. The resulting density distribution is interpreted with the help of a simple pinhole imaging model that assumes the 2H(d, p)3H reaction protons are emitted from a conical region extending from the tip of the anode to a fixed distance downstream. Comparison of the experimental track density profile with the model calculations supports the view that the beam-target mechanism is the dominant fusion production mechanism in this small plasma focus device.

Springham, Stuart Victor; Moo, Siew Pheng; Lee, Paul; Rawat, Rajdeep Singh; Patran, Alin Constantin; Lee, Sing

2005-06-01

40

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

41

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

42

Detection of nitrosyl–iron complexes by proton-electron–double-resonance imaging  

Microsoft Academic Search

The nitrogen monoxide radical (NO) forms paramagnetic mono- and dinitrosyl–iron complexes in biologic tissues. To establish a noninvasive technique for in vivo NO imaging, we evaluated the suitability of these complexes as magnetic resonance (MR) contrast agents, making use of the ability of the unpaired electrons of the complexes to enter into dynamic nuclear polarization with water protons and hence

Alexander Mülsch; David J Lurie; Ioannis Seimenis; Birgit Fichtlscherer; Margaret A Foster

1999-01-01

43

The value of water-excitation 3D FLASH and fat-saturated PDw TSE MR imaging for detecting and grading articular cartilage lesions of the knee  

Microsoft Academic Search

Objective To evaluate the diagnostic accuracy of water-excitation (WE) 3D FLASH and fat-saturated (FS) proton density-weighted (PDw) TSE MR imaging for detecting, grading, and sizing articular cartilage lesions of the knee. Design and patients A total of 26 patients underwent MR imaging prior to arthroscopy with the following sequences: (1) WE 3D FLASH: 28\\/11 ms, scan time: 4 min 58 s, flip angle:

Andreas Mohr

2003-01-01

44

Simulation of monoenergetic proton radiography images of ICF hohlraums and capsules  

NASA Astrophysics Data System (ADS)

A Monte-Carlo program is being developed for simulating radiographic images that could be obtained of objects of importance to the ICF program by using 14.7-MeV fusion protons from imploded ICF capsules with thin glass shells and D^3He fuel. Experiments we've performed at the OMEGA laser facility have already proven that such imaging is very good for studying the spatial distribution of B fields generated by laser-plasma interactions when the protons pass through small amounts of low-Z material (e.g. ˜ 1 mg/cm^2 of Al or CH). Other objects we would like to image, including high-Z hohlraums with laser-generated B fields, imploded ICF capsules, and various foils used for planar Rayleigh-Taylor experiments, will subject the protons to more scattering that will degrade image spatial resolution. We will present simulations of images of some of these objects and discuss the practical limits of this type of imaging technology. The work described here was performed in part at the LLE National Laser User's Facility (NLUF), and was supported in part by US DOE (Grant No. DE-FG03-03SF22691), LLNL (subcontract Grant No. B504974), and LLE (subcontract Grant No. 412160-001G).

Manuel, M.; Séguin, F. H.; McDuffee, S.; Li, C. K.; Casey, D. T.; Frenje, J. A.; Rygg, J. R.; Petrasso, R. D.; Smalyuk, V. A.

2006-10-01

45

Imaging of fusion protons from a 3 kJ deuterium plasma focus  

Microsoft Academic Search

This paper reports a study of the proton emission from a 3 kJ, 14 kV\\u000a plasma focus device operated with deuterium gas at 400 Pa. A filtered\\u000a pinhole camera with a 1.8 mm diameter hole is placed axially downstream\\u000a of the plasma focus, and images of the proton-emitting region are\\u000a recorded using CR-39\\/PM-355 nuclear track detectors. The detector plates\\u000a are

Stuart Victor Springham; Siew Pheng Moo; Paul Lee; Rajdeep Singh Rawat; Alin Constantin Patran; Sing Lee

2005-01-01

46

Phantom based evaluation of CT to CBCT image registration for proton therapy dose recalculation  

NASA Astrophysics Data System (ADS)

The ability to perform dose recalculation on the anatomy of the day is important in the context of adaptive proton therapy. The objective of this study was to investigate the use of deformable image registration (DIR) and cone beam CT (CBCT) imaging to generate the daily stopping power distribution of the patient. We investigated the deformation of the planning CT scan (pCT) onto daily CBCT images to generate a virtual CT (vCT) using a deformable phantom designed for the head and neck (H & N) region. The phantom was imaged at a planning CT scanner in planning configuration, yielding a pCT and in deformed, treatment day configuration, yielding a reference CT (refCT). The treatment day configuration was additionally scanned at a CBCT scanner. A Morphons DIR algorithm was used to generate a vCT. The accuracy of the vCT was evaluated by comparison to the refCT in terms of corresponding features as identified by an adaptive scale invariant feature transform (aSIFT) algorithm. Additionally, the vCT CT numbers were compared to those of the refCT using both profiles and regions of interest and the volumes and overlap (DICE coefficients) of various phantom structures were compared. The water equivalent thickness (WET) of the vCT, refCT and pCT were also compared to evaluate proton range differences. Proton dose distributions from the same initial fluence were calculated on the refCT, vCT and pCT and compared in terms of proton range. The method was tested on a clinical dataset using a replanning CT scan acquired close in time to a CBCT scan as reference using the WET evaluation. Results from the aSIFT investigation suggest a deformation accuracy of 2–3?mm. The use of the Morphon algorithm did not distort CT number intensity in uniform regions and WET differences between vCT and refCT were of the order of 2% of the proton range. This result was confirmed by proton dose calculations. The patient results were consistent with phantom observations. In conclusion, our phantom study suggests the vCT approach is adequate for proton dose recalculation on the basis of CBCT imaging.

Landry, Guillaume; Dedes, George; Zöllner, Christoph; Handrack, Josefine; Janssens, Guillaume; Orban de Xivry, Jonathan; Reiner, Michael; Paganelli, Chiara; Riboldi, Marco; Kamp, Florian; Söhn, Matthias; Wilkens, Jan J.; Baroni, Guido; Belka, Claus; Parodi, Katia

2015-01-01

47

Phantom based evaluation of CT to CBCT image registration for proton therapy dose recalculation.  

PubMed

The ability to perform dose recalculation on the anatomy of the day is important in the context of adaptive proton therapy. The objective of this study was to investigate the use of deformable image registration (DIR) and cone beam CT (CBCT) imaging to generate the daily stopping power distribution of the patient. We investigated the deformation of the planning CT scan (pCT) onto daily CBCT images to generate a virtual CT (vCT) using a deformable phantom designed for the head and neck (H & N) region.The phantom was imaged at a planning CT scanner in planning configuration, yielding a pCT and in deformed, treatment day configuration, yielding a reference CT (refCT). The treatment day configuration was additionally scanned at a CBCT scanner. A Morphons DIR algorithm was used to generate a vCT. The accuracy of the vCT was evaluated by comparison to the refCT in terms of corresponding features as identified by an adaptive scale invariant feature transform (aSIFT) algorithm. Additionally, the vCT CT numbers were compared to those of the refCT using both profiles and regions of interest and the volumes and overlap (DICE coefficients) of various phantom structures were compared. The water equivalent thickness (WET) of the vCT, refCT and pCT were also compared to evaluate proton range differences. Proton dose distributions from the same initial fluence were calculated on the refCT, vCT and pCT and compared in terms of proton range. The method was tested on a clinical dataset using a replanning CT scan acquired close in time to a CBCT scan as reference using the WET evaluation.Results from the aSIFT investigation suggest a deformation accuracy of 2-3?mm. The use of the Morphon algorithm did not distort CT number intensity in uniform regions and WET differences between vCT and refCT were of the order of 2% of the proton range. This result was confirmed by proton dose calculations. The patient results were consistent with phantom observations. In conclusion, our phantom study suggests the vCT approach is adequate for proton dose recalculation on the basis of CBCT imaging. PMID:25548912

Landry, Guillaume; Dedes, George; Zöllner, Christoph; Handrack, Josefine; Janssens, Guillaume; Orban de Xivry, Jonathan; Reiner, Michael; Paganelli, Chiara; Riboldi, Marco; Kamp, Florian; Söhn, Matthias; Wilkens, Jan J; Baroni, Guido; Belka, Claus; Parodi, Katia

2015-01-21

48

Noninvasive measurement and imaging of liver iron concentrations using proton magnetic resonance.  

PubMed

Measurement of liver iron concentration (LIC) is necessary for a range of iron-loading disorders such as hereditary hemochromatosis, thalassemia, sickle cell disease, aplastic anemia, and myelodysplasia. Currently, chemical analysis of needle biopsy specimens is the most common accepted method of measurement. This study presents a readily available noninvasive method of measuring and imaging LICs in vivo using clinical 1.5-T magnetic resonance imaging units. Mean liver proton transverse relaxation rates (R2) were measured for 105 humans. A value for the LIC for each subject was obtained by chemical assay of a needle biopsy specimen. High degrees of sensitivity and specificity of R2 to biopsy LICs were found at the clinically significant LIC thresholds of 1.8, 3.2, 7.0, and 15.0 mg Fe/g dry tissue. A calibration curve relating liver R2 to LIC has been deduced from the data covering the range of LICs from 0.3 to 42.7 mg Fe/g dry tissue. Proton transverse relaxation rates in aqueous paramagnetic solutions were also measured on each magnetic resonance imaging unit to ensure instrument-independent results. Measurements of proton transverse relaxivity of aqueous MnCl2 phantoms on 13 different magnetic resonance imaging units using the method yielded a coefficient of variation of 2.1%. PMID:15256427

St Pierre, Timothy G; Clark, Paul R; Chua-anusorn, Wanida; Fleming, Adam J; Jeffrey, Gary P; Olynyk, John K; Pootrakul, Pensri; Robins, Erin; Lindeman, Robert

2005-01-15

49

Proton magnetic resonance spectroscopic imaging suggests progressive neuronal damage in human temporal lobe epilepsy  

Microsoft Academic Search

Whether temporal lobe epilepsy (TLE) is the result of an isolated, early injury or whether there is ongoing neuronal damage due to seizures is often debated. We attempted to examine the long-term effect of seizures using proton magnetic resonance spectroscopic imaging (1H-MRSI), which can quantify neuronal loss or dysfunction based on reduced signals from the neuronal marker N-acetylaspartate (NAA). We

A. Bernasconi; E. Tasch; F. Cendes; L. M. Li; D. L. Arnold

2002-01-01

50

Proton magnetic resonance spectroscopic imaging in progressive supranuclear palsy, Parkinson's disease and corticobasal degeneration  

Microsoft Academic Search

Summary We used proton magnetic resonance spectroscopic imaging semiovale, and significantly reduced NA\\/Cho in the lentiform nucleus and parietal cortex. There were no significant (1H-MRSI) to assess the in vivo cortical and subcortical differences between Parkinson's disease patients and control neuronal involvement in progressive supranuclear palsy, subjects, or between patients groups in any individual region Parkinson's disease and corticobasal degeneration.

G. Tedeschi; I. Litvan; S. Bonavita; A. Bertolino; N. Lundbom; N. J. Patronas; M. Hallett

1997-01-01

51

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

52

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

E-print Network

Characterization of Lung Cancer by Amide Proton Transfer (APT) Imaging: An In-Vivo Study in the brain tumor. In this study, we tested the feasibility of in-vivo APT imaging of lung tumor malignant lung cancer cell lines. The results revealed that APT imaging is feasible to quantify lung tumors

Gao, Jinming

53

Prompt gamma imaging of proton pencil beams at clinical dose rate  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

54

Proton magnetic resonance imaging using a nitrogen-vacancy spin sensor.  

PubMed

Magnetic resonance imaging, with its ability to provide three-dimensional, elementally selective imaging without radiation damage, has had a revolutionary impact in many fields, especially medicine and the neurosciences. Although challenging, its extension to the nanometre scale could provide a powerful new tool for the nanosciences, especially if it can provide a means for non-destructively visualizing the full three-dimensional morphology of complex nanostructures, including biomolecules. To achieve this potential, innovative new detection strategies are required to overcome the severe sensitivity limitations of conventional inductive detection techniques. One successful example is magnetic resonance force microscopy, which has demonstrated three-dimensional imaging of proton NMR with resolution on the order of 10?nm, but with the requirement of operating at cryogenic temperatures. Nitrogen-vacancy (NV) centres in diamond offer an alternative detection strategy for nanoscale magnetic resonance imaging that is operable at room temperature. Here, we demonstrate two-dimensional imaging of (1)H NMR from a polymer test sample using a single NV centre in diamond as the sensor. The NV centre detects the oscillating magnetic field from precessing protons as the sample is scanned past the NV centre. A spatial resolution of ?12?nm is shown, limited primarily by the scan resolution. PMID:25531089

Rugar, D; Mamin, H J; Sherwood, M H; Kim, M; Rettner, C T; Ohno, K; Awschalom, D D

2015-02-01

55

Grey matter abnormalities in multiple sclerosis: proton magnetic resonance spectroscopic imaging.  

PubMed

Pathologically defined abnormalities in the cortical gray matter (GM) are well described in multiple sclerosis (MS) but are infrequently seen by conventional magnetic resonance imaging (MRI). We systematically evaluated 52 relapsing-remitting MS patients and 20 normal volunteers with high resolution MRI and short echo proton magnetic resonance spectroscopic imaging (MRSI). Individual tissue contributions to the spectroscopic voxels were estimated based on MRI that incorporated both CSF suppression and magnetization transfer, or double inversion images in which both CSF and GM were suppressed. Strong resonances in the 0.8 to 1.5 p.p.m. spectral region were observed in 13 MS patients. Image segmentation based on the MRI characteristics of tissues contributing to the spectroscopic voxels showed that these additional peaks originated mainly from GM. The presence of these additional peaks suggests that the normal appearance GM on MRI, is biochemically abnormal in a substantial proportion of relapsing-remitting MS patients. PMID:11548980

Sharma, R; Narayana, P A; Wolinsky, J S

2001-08-01

56

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

PubMed Central

Chemical exchange between water and labile protons from amino-acids, proteins and other molecules can be exploited to provide tissue contrast with magnetic resonance imaging (MRI) techniques. Using an off-resonance Spin-Locking (SL) scheme for signal preparation is advantageous because the image contrast can be tuned to specific exchange rates by adjusting SL pulse parameters. While the amide-proton transfer (APT) contrast is obtained optimally with steady-state preparation, using a low power and long irradiation pulse, image contrast from the faster amine-water proton exchange (APEX) is optimized in the transient state with a higher power and a shorter SL pulse. Our phantom experiments show that the APEX contrast is sensitive to protein and amino acid concentration, as well as pH. In vivo 9.4-T SL MRI data of rat brains with irradiation parameters optimized to slow exchange rates have a sharp peak at 3.5 ppm and also broad peak at ?2 to ?5 ppm, inducing negative contrast in APT-weighted images, while the APEX image has large positive signal resulting from a weighted summation of many different amine-groups. Brain ischemia induced by cardiac arrest decreases pure APT signal from ~1.7% to ~0%, and increases the APEX signal from ~8% to ~16%. In the middle cerebral artery occlusion (MCAO) model, the APEX signal shows different spatial and temporal patterns with large inter-animal variations compared to APT and water diffusion maps. Because of the similarity between the chemical exchange saturation transfer (CEST) and SL techniques, APEX contrast can also be obtained by a CEST approach using similar irradiation parameters. APEX may provide useful information for many diseases involving a change in levels of proteins, peptides, amino-acids, or pH, and may serve as a sensitive neuroimaging biomarker. PMID:21871570

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

2011-01-01

57

Lasers As Particle Accelerators In Medicine: From Laser-Driven Protons To Imaging With Thomson Sources  

SciTech Connect

We report our recent progress using a high-power, picosecond CO{sub 2} laser for Thomson scattering and ion acceleration experiments. These experiments capitalize on certain advantages of long-wavelength CO{sub 2} lasers, such as their high number of photons per energy unit and beneficial wavelength- scaling of the electrons' ponderomotive energy and critical plasma frequency. High X-ray fluxes produced in the interactions of the counter-propagating laser- and electron-beams for obtaining single-shot, high-contrast images of biological objects. The laser, focused on a hydrogen jet, generated a monoenergetic proton beam via the radiation-pressure mechanism. The energy of protons produced by this method scales linearly with the laser's intensity. We present a plan for scaling the process into the range of 100-MeV proton energy via upgrading the CO{sub 2} laser. This development will enable an advance to the laser-driven proton cancer therapy.

Pogorelsky, I. V.; Babzien, M.; Polyanskiy, M. N.; Yakimenko, V. [Brookhaven National Laboratory, Accelerator Test Facility, Upton NY 11973 (United States); Dover, N. P.; Palmer, C. A. J.; Najmudin, Z. [Blackett Laboratory, Imperial College London, SW7 2BW (United Kingdom); Shkolnikov, P. [State University of New York, Stony Brook, NY 11794 (United States); Williams, O.; Rosenzweig, J. [University of California, Los Angeles, Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); Oliva, P.; Carpinelli, M.; Golosio, B. [Struttura Dipartimentale di Matematica e Fisica, Univ. di Sassari and INFN, Sezione di Cagliari 07100 (Italy); Delogu, P.; Stefanini, A. [Dipartimento di Fisica 'E. Fermi', Universita di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy) and INFN, Sezione di Pisa 56127 (Italy); Endrizzi, M.

2011-06-01

58

Improved spectral data unfolding for radiochromic film imaging spectroscopy of laser-accelerated proton beams  

SciTech Connect

An improved method to unfold the space-resolved proton energy distribution function of laser-accelerated proton beams using a layered, radiochromic film (RCF) detector stack has been developed. The method takes into account the reduced RCF response near the Bragg peak due to a high linear energy transfer (LET). This LET dependence of the active RCF layer has been measured, and published data have been re-interpreted to find a nonlinear saturation scaling of the RCF response with stopping power. Accounting for the LET effect increased the integrated particle yield by 25% after data unfolding. An iterative, analytical, space-resolved deconvolution of the RCF response functions from the measured dose was developed that does not rely on fitting. After the particle number unfold, three-dimensional interpolation is performed to determine the spatial proton beam distribution for proton energies in-between the RCF data points. Here, image morphing has been implemented as a novel interpolation method that takes into account the energy-dependent, changing beam topology.

Schollmeier, M.; Geissel, M.; Sefkow, A. B. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Flippo, K. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2014-04-15

59

Improved spectral data unfolding for radiochromic film imaging spectroscopy of laser-accelerated proton beams.  

PubMed

An improved method to unfold the space-resolved proton energy distribution function of laser-accelerated proton beams using a layered, radiochromic film (RCF) detector stack has been developed. The method takes into account the reduced RCF response near the Bragg peak due to a high linear energy transfer (LET). This LET dependence of the active RCF layer has been measured, and published data have been re-interpreted to find a nonlinear saturation scaling of the RCF response with stopping power. Accounting for the LET effect increased the integrated particle yield by 25% after data unfolding. An iterative, analytical, space-resolved deconvolution of the RCF response functions from the measured dose was developed that does not rely on fitting. After the particle number unfold, three-dimensional interpolation is performed to determine the spatial proton beam distribution for proton energies in-between the RCF data points. Here, image morphing has been implemented as a novel interpolation method that takes into account the energy-dependent, changing beam topology. PMID:24784600

Schollmeier, M; Geissel, M; Sefkow, A B; Flippo, K A

2014-04-01

60

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

61

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

62

Correction of systematic errors in quantitative proton density mapping.  

PubMed

Interest in techniques yielding quantitative information about brain tissue proton densities is increasing. In general, all parameters influencing the signal amplitude are mapped in several acquisitions and then eliminated from the image data to obtain pure proton density weighting. Particularly, the measurement of the receiver coil sensitivity profile is problematic. Several methods published so far are based on the reciprocity theorem, assuming that receive and transmit sensitivities are identical. Goals of this study were (1) to determine quantitative proton density maps using an optimized variable flip angle method for T(1) mapping at 3 T, (2) to investigate if systematic errors can arise from insufficient spoiling of transverse magnetization, and (3) to compare two methods for mapping the receiver coil sensitivity, based on either the reciprocity theorem or bias field correction. Results show that insufficient spoiling yields systematic errors in absolute proton density of about 3-4 pu. A correction algorithm is proposed. It is shown that receiver coil sensitivity mapping based on the reciprocity theorem yields erroneous proton density values, whereas reliable data are obtained with bias field correction. Absolute proton density values in different brain areas, evaluated on six healthy subjects, are in excellent agreement with recent literature results. PMID:22144171

Volz, Steffen; Nöth, Ulrike; Deichmann, Ralf

2012-07-01

63

Dynamics of duskside proton aurora observed with the Svalbard all-sky imager and the IMAGE satellite under northward IMF condition : November 26, 2000 event  

NASA Astrophysics Data System (ADS)

Imaging of proton aurora is an excellent probe to monitor the magnetospheric dynamics. Particularly, imaging of high-latitude proton aurora enables us to investigate phenomena related to magnetospheric boundary processes. We have been operating an all-sky proton aurora imager at Longyearbyen (75.3 N invariant latitude) in Svalbard on a routine basis. In this paper, we focus on an interval 11-16 UT on November 26, 2000 when large enhancements of proton aurora occurred twice associated with the arrival of solar wind fast shocks identified by SSCs at 07:58 UT and 11:58 UT. The IMF observed by the WIND spacecraft was mostly northward (Bz = about 15 nT) during the period of 11-16 UT, except intermittent southward IMF turnings during the period of 12:22-13:18 UT and 14:50-15:08 UT. The averaged pressure, density and velocity of solar wind were 15 nPa, 20 /cc and 600 km/s, respectively. Enhancements of proton aurora in the dusk sector beginning at 11:58 T in association with SSC lasted over 40 min. Then quasi-periodic enhancements of proton aurora with a peak intensity of 300 R of Hb and a period of about 30 min occurred in the dusk sector in the following time period from 13:30 to 16:00 UT. By comparing proton aurora images obtained from the Svalbard all-sky imager and the IMAGE/FUV instrument with charged particle data obtained by DMSP and GEOTAIL spacecraft, it is suggested that these proton aurora enhancements are results of precipitation of protons with energy of about 10 keV in the boundary plasma sheet (BPS) adjacent to the dusk sector magnetopause. We also compared proton aurora images obtained at Longyearbyen with ionospheric plasma convection patterns obtained by the Super DARN network. From these data analyses, we clarify the mechanisms of these proton aurora enhancements in the dusk sector. We also discuss the injection processes of solar wind protons across the magnetopause and the heating and acceleration processes of injected protons in the magnetopause boundary region under northward IMF condition.

Yoshida, N.; Fukunishi, H.; Frey, H. U.; Mende, S. B.; Lester, M.; Mukai, T.; Smith, R. W.

2001-12-01

64

Projection imaging with directional electron and proton beams emitted from an ultrashort intense laser-driven thin foil target  

NASA Astrophysics Data System (ADS)

Projection images of a metal mesh produced by directional MeV electron beam together with directional proton beam, emitted simultaneously from a thin foil target irradiated by an ultrashort intense laser, are recorded on an imaging plate for the electron imaging and on a CR-39 nuclear track detector for the proton imaging. The directional electron beam means the portion of the electron beam which is emitted along the same direction (i.e., target normal direction) as the proton beam. The mesh patterns are projected to each detector by the electron beam and the proton beam originated from tiny virtual sources of ~20 µm and ~10?µm diameters, respectively. Based on the observed quality and magnification of the projection images, we estimate sizes and locations of the virtual sources for both beams and characterize their directionalities. To carry out physical interpretation of the directional electron beam qualitatively, we perform 2D particle-in-cell simulation which reproduces a directional escaping electron component, together with a non-directional dragged-back electron component, the latter mainly contributes to building a sheath electric field for proton acceleration. The experimental and simulation results reveal various possible applications of the simultaneous, synchronized electron and proton sources to radiography and pump-probe measurements with temporal resolution of ~ps and spatial resolution of a few tens of µm.

Nishiuchi, M.; Choi, I. W.; Daido, H.; Nakamura, T.; Pirozhkov, A. S.; Yogo, A.; Ogura, K.; Sagisaka, A.; Orimo, S.; Daito, I.; Bulanov, S. V.; Sung, J. H.; Lee, S. K.; Yu, T. J.; Jeong, T. M.; Kim, I. J.; Kim, C. M.; Kang, S. W.; Pae, K. H.; Oishi, Y.; Lee, J.

2015-02-01

65

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

66

Prompt gamma imaging of proton pencil beams at clinical dose rate.  

PubMed

In this work, we present experimental results of a prompt gamma camera for real-time proton beam range verification. The detection system features a pixelated Cerium doped lutetium based scintillation crystal, coupled to Silicon PhotoMultiplier arrays, read out by dedicated electronics. The prompt gamma camera uses a knife-edge slit collimator to produce a 1D projection of the beam path in the target on the scintillation detector. We designed the detector to provide high counting statistics and high photo-detection efficiency for prompt gamma rays of several MeV. The slit design favours the counting statistics and could be advantageous in terms of simplicity, reduced cost and limited footprint. We present the description of the realized gamma camera, as well as the results of the characterization of the camera itself in terms of imaging performance. We also present the results of experiments in which a polymethyl methacrylate phantom was irradiated with proton pencil beams in a proton therapy center. A tungsten slit collimator was used and prompt gamma rays were acquired in the 3-6 MeV energy range. The acquisitions were performed with the beam operated at 100 MeV, 160 MeV and 230 MeV, with beam currents at the nozzle exit of several nA. Measured prompt gamma profiles are consistent with the simulations and we reached a precision (2?) in shift retrieval of 4 mm with 0.5 × 10(8), 1.4 × 10(8) and 3.4 × 10(8) protons at 100, 160 and 230 MeV, respectively. We conclude that the acquisition of prompt gamma profiles for in vivo range verification of proton beam with the developed gamma camera and a slit collimator is feasible in clinical conditions. The compact design of the camera allows its integration in a proton therapy treatment room and further studies will be undertaken to validate the use of this detection system during treatment of real patients. PMID:25207724

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

2014-10-01

67

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

SciTech Connect

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

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

2013-04-15

68

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

PubMed

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. PMID:22572603

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

69

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

70

Amide Proton Transfer MR Imaging of Prostate Cancer: A Preliminary Study  

PubMed Central

Purpose To evaluate the capability of amide proton transfer (APT) MR imaging for detection of prostate cancer that typically shows a higher tumor cell proliferation rate and cellular density leading to an MRI-detectable overall elevated mobile protein level in higher grade tumors. Materials and Methods Twelve patients with biopsy-proven prostate cancer were imaged on a 3 Tesla MR imaging system before prostatectomy. APT-MR images were acquired by means of a single-slice single-shot turbo spin echo sequence with a saturation prepulse preparation using 33 different frequency offsets (?8 to 8 ppm, interval 0.5 ppm). For quantification we used the APT ratio (APTR) based on the asymmetry of the magnetization transfer ratio at 3.5 ppm in respect to the water signal. Tumor and peripheral zone benign regions of interest (ROIs) were delineated based on whole mount pathology slides after prostatectomy. Results APTR in prostate cancer ROIs was 5.8% 6 3.2%, significantly higher than that in the peripheral zone benign regions (0.3% ± 3.2%, P = 0.002). Conclusion APT-MR imaging is feasible in prostate cancer detection and has the potential to discriminate between cancer and noncancer tissues. PMID:21563248

Jia, Guang; Abaza, Ronney; Williams, JoAnna D.; Zynger, Debra L.; Zhou, Jinyuan; Shah, Zarine K.; Patel, Mitva; Sammet, Steffen; Wei, Lai; Bahnson, Robert R.; Knopp, Michael V.

2015-01-01

71

Image mosaic method for recognition of proton track in nuclear emulsions  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

72

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

PubMed Central

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

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

2013-01-01

73

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

75

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

PubMed

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

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

2014-07-01

76

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

77

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

78

Multi-angle Ratiometric Approach to Measure Chemical Exchange in Amide Proton Transfer (APT) imaging  

PubMed Central

Amide proton transfer (APT) imaging, a specific form of chemical exchange saturation transfer (CEST) imaging, has previously been applied to studies of acute ischemic acidosis, stroke, and cancer. However, interpreting the resulting contrast is complicated by its dependence on the exchange rate between amides and water, the amide concentration, amide and water relaxation, and macromolecular magnetization transfer. Hence, conventional CEST contrast is not specific to changes such as reductions in pH due to tissue acidosis. In this paper, a multi-angle ratiometric approach based on several pulsed-CEST scans at different irradiation flip angles is proposed to specifically reflect exchange rates only. This separation of exchange effects in pulsed-CEST experiments is based on isolating rotation vs. saturation contributions, and such methods form a new subclass of chemical exchange rotation transfer (CERT) experiments. Simulations and measurements of creatine/agar phantoms indicate that a newly proposed imaging metric isolates the effects of exchange rate changes, independent of other sample parameters. PMID:22161770

Zu, Zhongliang; Janve, Vaibhav A.; Li, Ke; Does, Mark D.; Gore, John C.; Gochberg, Daniel F.

2012-01-01

79

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

PubMed Central

Proton magnetic resonance spectroscopy (1H MRS) is a non-invasive imaging technique that permits measurement of particular compounds or metabolites within the tissue of interest. In the brain, 1H MRS provides a snapshot of the neurochemical environment within a defined volume of interest. A search of the literature demonstrates the widespread utility of this technique for characterizing tumors, tracking the progress of neurodegenerative disease, and for understanding the neurobiological basis of psychiatric disorders. As of relatively recently, 1H MRS has found its way into substance abuse research, and it is beginning to become recognized as a valuable complement in the brain imaging toolbox that also contains positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI). Drug abuse studies employing 1H MRS have identified a number biochemical changes in the brain. The most consistent alterations across drug class were reductions in N-acetylaspartate and elevations in myo-inositol, while changes in choline, creatine, and amino acid transmitters also were abundant. Together, the studies discussed herein provide evidence that drugs of abuse may have a profound impact on neuronal health, energy metabolism and maintenance, inflammatory processes, cell membrane turnover, and neurotransmission, and these biochemical changes may underlie the neuropathology within brain tissue that subsequently gives rise to the cognitive and behavioral impairments associated with drug addiction. PMID:20201852

Licata, Stephanie C.; Renshaw, Perry F.

2011-01-01

80

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

Microsoft Academic Search

In order to reduce the dose to surrounding critical tissues and also minimize the probability of recurrence of the tumor the placement of radiation fields relative to patient anatomy is very essential in proton beam therapy of ocular tumors. To achieve this objective, patient setup and field placement have been verified before treatment by analyzing the portal images obtained with

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

2009-01-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

82

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

PubMed

Organ motion is a major problem for any dynamic radiotherapy delivery technique, and is particularly so for spot scanned proton therapy. On the other hand, the use of narrow, magnetically deflected proton pencil beams is potentially an ideal delivery technique for tracking tumour motion on-line. At PSI, our new Gantry is equipped with a Beams Eye View (BEV) imaging system which will be able to acquire 2D x-ray images in fluoroscopy mode during treatment delivery. However, besides precisely tracking motion from BEVs, it is also essential to obtain information on the 3D motion vector throughout the whole region of interest, and any sparsely acquired surrogate motion is generally not sufficient to describe the deformable behaviour of the whole volume in three dimensions. In this study, we propose a method by which 3D deformable motions can be estimated from surrogate motions obtained using this monoscopic imaging system. The method assumes that example motions over a number of breathing cycles can be acquired before treatment for each patient using 4DMRI. In this study, for each of 11 different subjects, 100 continuous breathing cycles have been extracted from extended 4DMRI studies in the liver and then subject specific motion models have been built using principle component analysis (PCA). To simulate treatment conditions, a different set of 30 continuous breathing cycles from the same subjects have then been used to generate a set of simulated 4DCT data sets (so-called 4DCT(MRI) data sets), from which time-resolved digitally reconstructed radiographs (DRRs) were calculated using the BEV geometry for three treatment fields respectively. From these DRRs, surrogate motions from fiducial markers or the diaphragm have been used as a predictor to estimate 3D motions in the liver region for each subject. The prediction results have been directly compared to the 'ground truth' motions extracted from the same 30 breath cycles of the originating 4DMRI data set. Averaged over all 11 subjects, and for three field directions, for 99% of predicted positions, median (max) error magnitudes of better than 2.63(5.67) mm can be achieved when fiducial markers was chosen as predictor. Furthermore, three single fields, 4D dose calculations have been performed as a verification tool to evaluate the prediction performance of such a model in the context of scanned proton beam therapy. These show a high similarity between plans considering either PCA predicted motion or ground truth motion, where absolute dose differences of more than 5% (V(dosediff = 5%)) occur for the worst field scenarios in only 3.61% (median) or 15.13% (max) of dose calculation points in the irradiated volume. The magnitude of these dose differences were insignificantly dependent on whether surrogate motions were tracked by monoscopic or stereoscopic imaging systems, or whether fiducial markers or diaphragm were chosen as surrogate. This study has demonstrated that on-line deformable motion reconstruction from sparse surrogate motions is feasible, even when using only a monoscopic imaging system. In addition, it has also been found that diaphragm motion can be considered as a good predictor for respiratory deformable liver motion prediction, implying that fiducial markers might not be compulsory if used in conjunction with a patient specific PCA based model. PMID:24256693

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

2013-12-21

83

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

SciTech Connect

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

Bonnet, T.; Denis-Petit, D.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Aleonard, M. M. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, Universite de Bordeaux, UMR 5797 CNRS/IN2P3, Gradignan 33175 (France); Comet, M. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, Universite de Bordeaux, UMR 5797 CNRS/IN2P3, Gradignan 33175 (France); CEA, DAM, DIF, F-91297 Arpajon (France)

2013-01-15

84

Calibration of water proton chemical shift with temperature for noninvasive temperature imaging during focused ultrasound surgery.  

PubMed

The present work was performed to calibrate water proton chemical shift change with tissue temperature in vivo to establish a method of quantitative temperature imaging during focused ultrasound surgery. The chemical shift change measured with a phase-mapping method using spoiled gradient-recalled acquisition in steady state (SPGR) (TR = 26 msec, TE = 12.8 msec, matrix = 256 x 128) was calibrated with the corresponding temperature elevation (0-50 degrees C, 32-84 degrees C in absolute temperature) measured with a copper-constantan thermocouple (.05-mm-diameter bare wires) in rabbit skeletal muscle (16 animals) under focused ultrasound exposures (10-100 W radiofrequency [RF] power, 20-second sonication). A linear calibration with a regression coefficient of (-8.76+/-.69) x 10(-3) ppm/degrees C (P < .01 [P, significance level]) was obtained. Temperature distributions during a 20-second sonication were visualized every 3.3 seconds with a 2.3-mm3 spatial resolution and 4 degrees C temperature uncertainty. PMID:9500277

Kuroda, K; Chung, A H; Hynynen, K; Jolesz, F A

1998-01-01

85

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

PubMed Central

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

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

2014-01-01

86

Long-term stability and mechanical characteristics of kV digital imaging system for proton radiotherapy  

SciTech Connect

Purpose: To quantitatively evaluate the long-term image panel positioning stability and gantry angle dependence for gantry-mounted kV imaging systems. Methods: For patient setup digital imaging systems in isocentric rotating proton beam delivery facilities, physical crosshairs are commonly inserted into the snout to define the kV x-ray beam isocenter. Utilizing an automatic detection algorithm, the authors analyzed the crosshair center positions in 2744 patient setup kV images acquired with the four imagers in two treatment rooms from January 2012 to January 2013. The crosshair position was used as a surrogate for imaging panel position, and its long-term stability at the four cardinal angles and the panel flex dependency on gantry angle was investigated. Results: The standard deviation of the panel position distributions was within 0.32 mm (with the range of variation less than ± 1.4 mm) in both the X-Z plane and Y direction. The mean panel inplane rotations were not more than 0.51° for the four panels at the cardinal angles, with standard deviations ?0.26°. The panel position variations with gantry rotation due to gravity (flex) were within ±4 mm, and were panel-specific. Conclusions: The authors demonstrated that the kV image panel positions in our proton treatment system were highly reproducible at the cardinal angles over 13 months and also that the panel positions can be correlated to gantry angles. This result indicates that the kV image panel positions are stable over time; the amount of panel sag is predictable during gantry rotation and the physical crosshair for kV imaging may eventually be removed, with the imaging beam isocenter position routinely verified by adequate quality assurance procedures and measurements.

Zhu, Mingyao, E-mail: mzhu4@mgh.harvard.edu; Botticello, Thomas; Lu, Hsiao-Ming; Winey, Brian [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 (United States)] [Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 (United States)

2014-04-15

87

A silicon pixel detector system as an imaging tool for proton beam characterization  

Microsoft Academic Search

High energy protons represent a very promising alternative in the tumor irradiation, as respect the photon and electron beams. In Italy, the first and at present the only proton-therapy facility, CATANA (Centro di AdroTerapia e Applicazioni Nucleari Avanzate), was built in Catania, at the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS). Here a 62 MeV proton beam, produced

M. G. Bisogni; G. A. P. Cirrone; G. Cuttone; A. D el Guerra; P. Lojacono; M. A. Piliero; F. Romano; V. Rosso; V. Sipala; A. Stefanini; S. Vecchio

2008-01-01

88

Proton magnetic resonance spectroscopic imaging in the clinical evaluation of patients with Niemann-Pick type C disease  

Microsoft Academic Search

OBJECTIVES10 patients with Niemann-Pick disease type C (NP-C) were studied by proton magnetic resonance spectroscopic imaging (1H-MRSI) to assess the biochemical pathology of the brain and to determine whether this method can be useful to clinically evaluate these patients.METHODS1H-MRSI permits the simultaneous measurement of N-acetyl aspartate (NA), compounds containing choline (Cho), creatine plus phosphocreatine (Cre), and lactate (Lac) signal intensities

G Tedeschi; S Bonavita; N W Barton; A Bertolino; J A Frank; N J Patronas; J R Alger; R Schiffmann

1998-01-01

89

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

PubMed Central

The purpose of this study was to investigate magnetic resonance imaging of the normal canine and feline eye, orbit and optic nerves using proton density-weighted, T1-weighted and T2-weighted images. The clinical application of magnetic resonance imaging in veterinary ophthalmology was also investigated using three clinical cases: a feline orbital melanoma, a feline optic nerve meningioma, and a canine orbital fibrosarcoma. Gadolinium diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging was completed on the case of feline optic nerve meningioma. Magnetic resonance imaging provides excellent anatomical detail of the canine and feline eye, orbit, and optic nerves due to its superior soft tissue contrast, and its multiplanar and multislice imaging capability. Therefore it is of value for diagnostic imaging of some ophthalmic and neuro-ophthalmic conditions in the dog and cat. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8. PMID:17424252

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

1993-01-01

90

Estimation of Hepatic Proton-Density Fat Fraction by Using MR Imaging at 3.0 T  

PubMed Central

Purpose: To compare the accuracy of several magnetic resonance (MR) imaging–based methods for hepatic proton-density fat fraction (FF) estimation at 3.0 T, with spectroscopy as the reference technique. Materials and Methods: This prospective study was institutional review board approved and HIPAA compliant. Informed consent was obtained. One hundred sixty-three subjects (39 with known hepatic steatosis, 110 with steatosis risk factors, 14 without risk factors) underwent proton MR spectroscopy and non–T1-weighted gradient-echo MR imaging of the liver. At spectroscopy, the reference FF was determined from frequency-selective measurements of fat and water proton densities. At imaging, FF was calculated by using two-, three-, or six-echo methods, with single-frequency and multifrequency fat signal modeling. The three- and six-echo methods corrected for T2*; the two-echo methods did not. For each imaging method, the fat estimation accuracy was assessed by using linear regression between the imaging FF and spectroscopic FF. Binary classification accuracy of imaging was assessed at four reference spectroscopic thresholds (0.04, 0.06, 0.08, and 0.10 FF). Results: Regression intercept of two-, three-, and six-echo methods were ?0.0211, 0.0087, and ?0.0062 (P <.001 for all three) without multifrequency modeling and ?0.0237 (P <.001), 0.0022, and ?0.0007 with multifrequency modeling, respectively. Regression slope of two-, three-, and six-echo methods were 0.8522, 0.8528, and 0.7544 (P <.001 for all three) without multifrequency modeling and 0.9994, 0.9775, and 0.9821 with multifrequency modeling, respectively. Significant deviation of intercept and slope from 0 and 1, respectively, indicated systematic error. Classification accuracy was 82.2%–90.1%, 93.9%–96.3%, and 83.4%–89.6% for two-, three-, and six-echo methods without multifrequency modeling and 88.3%–92.0%, 95.1%–96.3%, and 94.5%–96.3% with multifrequency modeling, respectively, depending on the FF threshold. T2*-corrected (three- and six-echo) multifrequency imaging methods had the overall highest FF estimation and classification accuracy. Among methods without multifrequency modeling, the T2*-corrected three-echo method had the highest accuracy. Conclusion: Non–T1-weighted MR imaging with T2* correction and multifrequency modeling helps accurately estimate hepatic proton-density FF at 3.0 T. © RSNA, 2011 PMID:21212366

Yokoo, Takeshi; Shiehmorteza, Masoud; Hamilton, Gavin; Wolfson, Tanya; Schroeder, Michael E.; Middleton, Michael S.; Bydder, Mark; Gamst, Anthony C.; Kono, Yuko; Kuo, Alexander; Patton, Heather M.; Horgan, Santiago; Lavine, Joel E.; Schwimmer, Jeffrey B.

2011-01-01

91

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

PubMed

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

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

2013-07-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

93

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

PubMed

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

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

2014-02-01

94

Online image guided tumour tracking with scanned proton beams: a comprehensive simulation study.  

PubMed

Tumour tracking with scanned particle beams potentially requires accurate 3D information on both tumour motion and related density variations. We have previously developed a model-based motion reconstruction method, which allows for the prediction of deformable motions from sparsely sampled surrogate motions tracked via an on-board imaging system (Zhang et al (2013 Phys. Med. Biol. 58 8621)). Here, we investigate the potential effectiveness of tumour tracking for scanned proton beam therapy using such an approach to guide scanned beam tracking, together with the effectiveness of 're-tracking' for reducing residual motion effects due to tracking uncertainties. Three different beam tracking strategies (2D, 2D deformable and 3D) have been applied to three different liver motion cases, with mean magnitudes ranging from 10-20?mm. All simulations have been performed using simulated 4DCTs derived from 4DMRI datasets, whereby inter-breath-cycle motion variability is taken into account. The results show that, without beam tracking, large interplay effects are observed for all motion cases, resulting in CTV D5-95 values of 34.9/58.5/79.4% for the three cases, respectively. These can be reduced to 16.9/18.8/29.1% with 2D tracking, to 15.5/17.9/23.3% with 2D deformable tracking and to 15.1/17.8/21.0% with 3D tracking. Clear 'inverse interplay' effects have also been observed in the proximal portion of the field. However, with three-times re-tracking, D5-95 for the largest motions (20?mm) can be reduced to 13.0/12.8% for 2D and 3D tracking, respectively, and 'hot spots' resulting from the 'inverse interplay' effect can be substantially reduced. In summary, we have found that, for motions over 10?mm, tracking alone cannot fully mitigate motion effects, and can lead to substantially increased doses to normal tissues in the entrance path of the field. However, three-times re-tracking substantially improves the effectiveness of all types of beam tracking, with substantial advantages of 3D over 2D re-tracking only being observed for the largest motion scenario investigated. PMID:25420088

Zhang, Ye; Knopf, A; Tanner, C; Lomax, A J

2014-11-24

95

Imaging of amide proton transfer and nuclear Overhauser enhancement in ischemic stroke with corrections for competing effects.  

PubMed

Chemical exchange saturation transfer (CEST) potentially provides the ability to detect small solute pools through indirect measurements of attenuated water signals. However, CEST effects may be diluted by various competing effects, such as non-specific magnetization transfer (MT) and asymmetric MT effects, water longitudinal relaxation (T1 ) and direct water saturation (radiofrequency spillover). In the current study, CEST images were acquired in rats following ischemic stroke and analyzed by comparing the reciprocals of the CEST signals at three different saturation offsets. This combined approach corrects the above competing effects and provides a more robust signal metric sensitive specifically to the proton exchange rate constant. The corrected amide proton transfer (APT) data show greater differences between the ischemic and contralateral (non-ischemic) hemispheres. By contrast, corrected nuclear Overhauser enhancements (NOEs) around -3.5?ppm from water change over time in both hemispheres, indicating whole-brain changes that have not been reported previously. This study may help us to better understand the contrast mechanisms of APT and NOE imaging in ischemic stroke, and may also establish a framework for future stroke measurements using CEST imaging with spillover, MT and T1 corrections. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25483870

Li, Hua; Zu, Zhongliang; Zaiss, Moritz; Khan, Imad S; Singer, Robert J; Gochberg, Daniel F; Bachert, Peter; Gore, John C; Xu, Junzhong

2015-02-01

96

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

PubMed Central

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

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

2013-01-01

97

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

98

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

99

Experimental Evaluation Of High Speed Ccd Imager Radiation Effects Using Co60 And Proton Radiation  

Microsoft Academic Search

We have completed a Series of CO60 and 8 and 25 MeV proton irradiations of wafer test structures and complete CCD detectors in order to study the changes in threshold voltage, dark current and charge transfer inefficiency (err) of CCD devices with very fast frame readout rates and large pixel geometries. Significant threshold voltage shifts for floating difhsion some followex

T. L. Miller; D. A. Thompson; M. B. Elzinga; T.-H. Lee; B. C. Passenheim; R. E. Leadon

1993-01-01

100

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

101

Total electron and proton energy input during auroral substorms: Remote sensing with IMAGE-FUV  

E-print Network

] The IMAGE satellite carries three FUV imagers observing N2 LBH, O I 1356 A° , and HI Lyman a emissions contribution to the N2 LBH and O I 1356 A° emissions is calculated and subtracted to obtain the electron

California at Berkeley, University of

102

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

PubMed

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

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

2013-06-21

103

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

104

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

105

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

PubMed

In this paper, we study the feasibility of using the stochastic origin ensemble (SOE) algorithm for reconstructing images of secondary gammas emitted during proton radiotherapy from data measured with a three-stage Compton camera. The purpose of this study was to evaluate the quality of the images of the gamma rays emitted during proton irradiation produced using the SOE algorithm and to measure how well the images reproduce the distal falloff of the beam. For our evaluation, we performed a Monte Carlo simulation of an ideal three-stage Compton camera positioned above and orthogonal to a proton pencil beam irradiating a tissue phantom. Scattering of beam protons with nuclei in the phantom produces secondary gamma rays, which are detected by the Compton camera and used as input to the SOE algorithm. We studied the SOE reconstructed images as a function of the number of iterations, the voxel probability parameter, and the number of detected gammas used by the SOE algorithm. We quantitatively evaluated the capabilities of the SOE algorithm by calculating and comparing the normalized mean square error (NMSE) of SOE reconstructed images. We also studied the ability of the SOE reconstructed images to predict the distal falloff of the secondary gamma production in the irradiated tissue. Our results show that the images produced with the SOE algorithm converge in ~10,000 iterations, with little improvement to the image NMSE for iterations above this number. We found that the statistical noise of the images is inversely proportional to the ratio of the number of gammas detected to the SOE voxel probability parameter value. In our study, the SOE predicted distal falloff of the reconstructed images agrees with the Monte Carlo calculated distal falloff of the gamma emission profile in the phantom to within ±0.6 mm for the positions of maximum emission (100%) and 90%, 50% and 20% distal falloff of the gamma emission profile. We conclude that the SOE algorithm is an effective method for reconstructing images of a proton pencil beam from the data collected by an ideal Compton camera and that these images accurately model the distal falloff of secondary gamma emission during proton irradiation. PMID:22588144

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

2012-06-01

106

Issues involved in the quantitative 3D imaging of proton doses using optical CT and chemical dosimeters.  

PubMed

Dosimetry of proton beams using 3D imaging of chemical dosimeters is complicated by a variation with proton linear energy transfer (LET) of the dose-response (the so-called 'quenching effect'). Simple theoretical arguments lead to the conclusion that the total absorbed dose from multiple irradiations with different LETs cannot be uniquely determined from post-irradiation imaging measurements on the dosimeter. Thus, a direct inversion of the imaging data is not possible and the proposition is made to use a forward model based on appropriate output from a planning system to predict the 3D response of the dosimeter.In addition to the quenching effect, it is well known that chemical dosimeters have a non-linear response at high doses. To the best of our knowledge it has not yet been determined how this phenomenon is affected by LET. The implications for dosimetry of a number of potential scenarios are examined.Dosimeter response as a function of depth (and hence LET) was measured for four samples of the radiochromic plastic PRESAGE(®), using an optical computed tomography readout and entrance doses of 2.0?Gy, 4.0?Gy, 7.8?Gy and 14.7?Gy, respectively. The dosimeter response was separated into two components, a single-exponential low-LET response and a LET-dependent quenching. For the particular formulation of PRESAGE(®) used, deviations from linearity of the dosimeter response became significant for doses above approximately 16?Gy.In a second experiment, three samples were each irradiated with two separate beams of 4?Gy in various different configurations. On the basis of the previous characterizations, two different models were tested for the calculation of the combined quenching effect from two contributions with different LETs. It was concluded that a linear superposition model with separate calculation of the quenching for each irradiation did not match the measured result where two beams overlapped. A second model, which used the concept of an 'effective dose' matched the experimental results more closely. An attempt was made to measure directly the quench function for two proton beams as a function of all four variables of interest (two physical doses and two LET values). However, this approach was not successful because of limitations in the response of the scanner. PMID:25555069

Doran, Simon; Gorjiara, Tina; Kacperek, Andrzej; Adamovics, John; Kuncic, Zdenka; Baldock, Clive

2015-01-21

107

Issues involved in the quantitative 3D imaging of proton doses using optical CT and chemical dosimeters  

NASA Astrophysics Data System (ADS)

Dosimetry of proton beams using 3D imaging of chemical dosimeters is complicated by a variation with proton linear energy transfer (LET) of the dose–response (the so-called ‘quenching effect’). Simple theoretical arguments lead to the conclusion that the total absorbed dose from multiple irradiations with different LETs cannot be uniquely determined from post-irradiation imaging measurements on the dosimeter. Thus, a direct inversion of the imaging data is not possible and the proposition is made to use a forward model based on appropriate output from a planning system to predict the 3D response of the dosimeter. In addition to the quenching effect, it is well known that chemical dosimeters have a non-linear response at high doses. To the best of our knowledge it has not yet been determined how this phenomenon is affected by LET. The implications for dosimetry of a number of potential scenarios are examined. Dosimeter response as a function of depth (and hence LET) was measured for four samples of the radiochromic plastic PRESAGE®, using an optical computed tomography readout and entrance doses of 2.0?Gy, 4.0?Gy, 7.8?Gy and 14.7?Gy, respectively. The dosimeter response was separated into two components, a single-exponential low-LET response and a LET-dependent quenching. For the particular formulation of PRESAGE® used, deviations from linearity of the dosimeter response became significant for doses above approximately 16?Gy. In a second experiment, three samples were each irradiated with two separate beams of 4?Gy in various different configurations. On the basis of the previous characterizations, two different models were tested for the calculation of the combined quenching effect from two contributions with different LETs. It was concluded that a linear superposition model with separate calculation of the quenching for each irradiation did not match the measured result where two beams overlapped. A second model, which used the concept of an ‘effective dose’ matched the experimental results more closely. An attempt was made to measure directly the quench function for two proton beams as a function of all four variables of interest (two physical doses and two LET values). However, this approach was not successful because of limitations in the response of the scanner.

Doran, Simon; Gorjiara, Tina; Kacperek, Andrzej; Adamovics, John; Kuncic, Zdenka; Baldock, Clive

2015-01-01

108

Contour-based brain segmentation method for magnetic resonance imaging human head scans.  

PubMed

The high-resolution magnetic resonance brain images often contain some nonbrain tissues (ie, skin, fat, muscle, neck, eye balls, etc) compared with the functional images such as positron emission tomography, single-photon emission computed tomography, and functional magnetic resonance imaging (MRI) scans, which usually contain few nonbrain tissues. Automatic segmentation of brain tissues from MRI scans remains a challenging task due to the variation in shape and size, use of different pulse sequences, overlapping signal intensities and imaging artifacts. This article presents a contour-based automatic brain segmentation method to segment the brain regions from T1-, T2-, and proton density-weighted MRI of human head scans. The proposed method consists of 2 stages. In stage 1, the brain regions in the middle slice is extracted. Many of the existing methods failed to extract brain regions in the lower and upper slices of the brain volume, where the brain appears in more than 1 connected region. To overcome this problem, in the proposed method, a landmark circle is drawn at the center of the extracted brain region of a middle slice and is likely to pass through all the brain regions in the remaining lower and upper slices irrespective of whether the brain is composed of 1 or more connected components. In stage 2, the brain regions in the remaining slices are extracted with reference to the landmark circle obtained in stage 1. The proposed method is robust to the variability of brain anatomy, image orientation, and image type, and it extracts the brain regions accurately in T1-, T2-, and proton density-weighted normal and abnormal brain images. Experimental results by applying the proposed method on 100 volumes of brain images show that the proposed method exhibits best and consistent performance than by the popular existing methods brain extraction tool, brain surface extraction, watershed algorithm, hybrid watershed algorithm, and skull stripping using graph cuts. PMID:23674005

Somasundaram, K; Kalavathi, P

2013-01-01

109

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

PubMed Central

The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of the detector itself. In addition to PET alone, PET/CT imaging provides accurate information on the position of the imaged object and may assess possible anatomical changes during fractionated radiotherapy in clinical applications. PMID:17388158

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

2008-01-01

110

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

SciTech Connect

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

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

2007-02-15

111

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. PMID:19605403

Ortega, Richard; Devès, Guillaume; Carmona, Asunción

2009-01-01

112

NOTE: Detection limits for ferrimagnetic particle concentrations using magnetic resonance imaging based proton transverse relaxation rate measurements  

NASA Astrophysics Data System (ADS)

A clinical magnetic resonance imaging (MRI) system was used to measure proton transverse relaxation rates (R2) in agar gels with varying concentrations of ferrimagnetic iron oxide nanoparticles in a field strength of 1.5 T. The nanoparticles were prepared by coprecipitation of ferric and ferrous ions in the presence of either dextran or polyvinyl alcohol. The method of preparation resulted in loosely packed clusters (dextran) or branched chains (polyvinyl alcohol) of particles containing of the order of 600 and 400 particles, respectively. For both methods of particle preparation, concentrations of ferrimagnetic iron in agar gel less than 0.01 mg ml-1 had no measurable effect on the value of R2 for the gel. The results indicate that MRI-based R2 measurements using 1.5 T clinical scanners are not quite sensitive enough to detect the very low concentrations of nanoparticulate biogenic magnetite reported in human brain tissue.

Pardoe, H.; Chua-anusorn, W.; St. Pierre, T. G.; Dobson, J.

2003-03-01

113

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

E-print Network

Proton imaging of hohlraum plasma stagnation in inertial-confinement-fusion experiments This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2013 Nucl.103.154.163 The article was downloaded on 12/06/2013 at 02:37 Please note that terms and conditions apply. View the table

114

Combination of Image Registration Algorithms for Patient Alignement in Proton Beam Therapy  

Microsoft Academic Search

\\u000a We propose a measure of patient alignment in a video by combining different image representations : grey level, edges, and\\u000a a set of feature points. When patient head is correctly positionned, a reference image with its ellipse is stored as a template\\u000a of correct alignment. Edges detection results in a second template of the correct head location. Corners inside the

Rachid Belaroussi; Guillaume Morel

2008-01-01

115

The Hippocampus in Patients Treated With Electroconvulsive Therapy: A Proton Magnetic Resonance Spectroscopic Imaging Study  

Microsoft Academic Search

Background: We monitored the effect of electrocon- vulsive therapy (ECT) on the nuclear magnetic resonance- detectable metabolites N-acetylaspartate, creatine and phosphocreatine, and choline-containing compounds in the hippocampus by means of hydrogen 1 magnetic reso- nance spectroscopic imaging. We hypothesized that if ECT-induced memory deterioration was associated with neuronal loss in the hippocampus, the N-acetylaspar- tate signal would decrease after ECT

Gabriele Ende; Dieter F. Braus; Sigrid Walter; Wolfgang Weber-Fahr; Fritz A. Henn

2000-01-01

116

Proton: The Particle  

SciTech Connect

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

Suit, Herman

2013-11-01

117

Assessing porosity of proton exchange membrane fuel cell gas diffusion layers by scanning electron microscope image analysis  

NASA Astrophysics Data System (ADS)

A gas diffusion layer (GDL) in a proton exchange membrane fuel cell may consist of several, materials of different porosities, with each material serving a specific set of functions. For example, samples analyzed in this work consisted of a macro porous carbon paper substrate treated with a, hydrophobic wet proofing material in differing amounts, which was then coupled to a micro porous, layer. The porosities of four such GDLs were determined by using 2D scanning electron microscope (SEM) images to mathematically model the volumes filled by each solid in the 3D structures. Results, were then compared with mercury intrusion porosimetry (MIP) measurements to verify the accuracy, of the method. It was found that the use of SEM not only allowed for detailed porosity analysis of, separate porous materials within the GDL, but also porosity for the entire GDL could be calculated for, the seemingly complex structures with reasonable accuracy. With some basic geometric assumptions, and use of the superposition principle, the calculated results were accurate to less than a 2% absolute, difference of the porosity measured by MIP for each of the four samples analyzed.

Farmer, Johnathon; Duong, Binh; Seraphin, Supapan; Shimpalee, Sirivatch; Martínez-Rodríguez, Michael J.; Van Zee, John W.

2012-01-01

118

Proton Therapy  

MedlinePLUS

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

119

Image-guided method for TLD-based in vivo rectal dose verification with endorectal balloon in proton therapy for prostate cancer  

SciTech Connect

Purpose: To present a practical image-guided method to position an endorectal balloon that improves in vivo thermoluminiscent dosimeter (TLD) measurements of rectal doses in proton therapy for prostate cancer. Methods: TLDs were combined with endorectal balloons to measure dose at the anterior rectal wall during daily proton treatment delivery. Radiopaque metallic markers were employed as surrogates for balloon position reproducibility in rotation and translation. The markers were utilized to guide the balloon orientation during daily treatment employing orthogonal x-ray image-guided patient positioning. TLDs were placed at the 12 o'clock position on the anterior balloon surface at the midprostatic plane. Markers were placed at the 3 and 9 o'clock positions on the balloon to align it with respect to the planned orientation. The balloon rotation along its stem axis, referred to as roll, causes TLD displacement along the anterior-posterior direction. The magnitude of TLD displacement is revealed by the separation distance between markers at opposite sides of the balloon on sagittal x-ray images. Results: A total of 81 in vivo TLD measurements were performed on six patients. Eighty-three percent of all measurements (65 TLD readings) were within +5% and -10% of the planning dose with a mean of -2.1% and a standard deviation of 3.5%. Examination of marker positions with in-room x-ray images of measured doses between -10% and -20% of the planned dose revealed a strong correlation between balloon roll and TLD displacement posteriorly from the planned position. The magnitude of the roll was confirmed by separations of 10-20 mm between the markers which could be corrected by manually adjusting the balloon position and verified by a repeat x-ray image prior to proton delivery. This approach could properly correct the balloon roll, resulting in TLD positioning within 2 mm along the anterior-posterior direction. Conclusions: Our results show that image-guided TLD-based in vivo dosimetry for rectal dose verification can be perfomed reliably and reproducibly for proton therapy in prostate cancer.

Hsi, Wen C.; Fagundes, Marcio; Zeidan, Omar [ProCure Proton Therapy Center, Oklahoma City, Oklahoma 73142 (United States); Hug, Eugen [ProCure Proton Therapy Centers, New York, New York 10016 (United States); Schreuder, Niek [ProCure Training and Development Center, Bloomington, Indiana 47404 (United States)

2013-05-15

120

Advanced MR imaging techniques in the evaluation of nonenhancing gliomas: perfusion-weighted imaging compared with proton magnetic resonance spectroscopy and tumor grade.  

PubMed

A significant number of nonenhancing (NE) gliomas are reported to be malignant. The purpose of this study was to compare the value of advanced MR imaging techniques, including T2*-dynamic susceptibility contrast PWI (DSC-PWI) and proton magnetic resonance spectroscopy ((1)HMRS) in the evaluation of NE gliomas. Twenty patients with NE gliomas underwent MRI including DSC-PWI and (1)HMRS. The relative CBV (rCBV) measurements were obtained from regions of maximum perfusion. The peak ratios of choline/creatine (Cho/Cr) and myo-inositol/creatine (mIns/Cr) were measured at a TE of 30 ms. Demographic features, tumor volumes, and PWI- and (1)HMRS-derived measures were compared between low-grade gliomas (LGGs) and high-grade gliomas (HGGs). In addition, the association of initial rCBV ratio with tumor progression was evaluated in LGGs. No significant difference was noted in age, sex or tumor size between LGGs and HGGs. Cho/Cr ratios were significantly higher in HGGs (1.7±0.63) than in LGGs (1.2±0.38). The receiver operating characteristic analysis demonstrated that a Cho/Cr ratio with a cutoff value of 1.3 could differentiate between LGG and HGG with a specificity of 100% and a sensitivity of 71.4%. There was no significant difference in the rCBV ratio and the mIns/Cr ratio between LGG and HGG. However, higher rCBV ratios were observed with more rapid progressions in LGGs. The results imply that Cho/Cr ratios are useful in distinguishing NE LGG from HGG and can be helpful in preoperative grading and biopsy guidance. On the other hand, rCBV ratios do not help in the distinction. PMID:24199813

Sahin, Neslin; Melhem, Elias R; Wang, Sumei; Krejza, Jaroslaw; Poptani, Harish; Chawla, Sanjeev; Verma, Gaurav

2013-10-01

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

Imaging of articular cartilage: current concepts  

PubMed Central

Magnetic resonance imaging (MRI) is the gold standard method for non-invasive assessment of joint cartilage, providing information on the structure, morphology and molecular composition of this tissue. There are certain minimum requirements for a MRI study of cartilage tissue: machines with a high magnetic field (> 1.5 Tesla); the use of surface coils; and the use of T2-weighted, proton density-weighted fast-spin echo (T2 FSE-DP) and 3D fat-suppressed T1-weighted gradient echo (3D-FS T1W GRE) sequences. For better contrast between the different joint structures, MR arthography is a method that can highlight minimal fibrillation or fractures of the articular surface and allow evaluation of the integrity of the native cartilage-repair tissue interface. To assess the biochemical composition of cartilage and cartilage repair tissue, various techniques have been proposed for studying proteoglycans [dGEMRIC, T1rho mapping, sodium (23Na) imaging MRI, etc.], collagen, and water distribution [T2 mapping, “magnetisation transfer contrast”, diffusion-weighted imaging (DWI), and so on]. Several MRI classifications have been proposed for evaluating the processes of joint degeneration (WORMS, BLOKS, ICRS) and post-surgical maturation of repair tissue (MOCART, 3D MOCART). In the future, isotropic 3D sequences set to improve image quality and facilitate the diagnosis of disorders of articular structures adjacent to cartilage.

RONGA, MARIO; ANGERETTI, GLORIA; FERRARO, SERGIO; DE FALCO, GIOVANNI; GENOVESE, EUGENIO A.; CHERUBINO, PAOLO

2014-01-01

123

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

PubMed Central

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

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

2011-01-01

124

The localization-delocalization matrix and the electron-density-weighted connectivity matrix of a finite graphene nanoribbon reconstructed from kernel fragments.  

PubMed

Bader's quantum theory of atoms in molecules (QTAIM) and chemical graph theory, merged in the localization-delocalization matrices (LDMs) and the electron-density-weighted connectivity matrices (EDWCM), are shown to benefit in computational speed from the kernel energy method (KEM). The LDM and EDWCM quantum chemical graph matrices of a 66-atom C46H20 hydrogen-terminated armchair graphene nanoribbon, in 14 (2×7) rings of C2v symmetry, are accurately reconstructed from kernel fragments. (This includes the full sets of electron densities at 84 bond critical points and 19 ring critical points, and the full sets of 66 localization and 4290 delocalization indices (LIs and DIs).) The average absolute deviations between KEM and directly calculated atomic electron populations, obtained from the sum of the LIs and half of the DIs of an atom, are 0.0012 ± 0.0018 e(-) (?0.02 ± 0.03%) for carbon atoms and 0.0007 ± 0.0003 e(-) (?0.01 ± 0.01%) for hydrogen atoms. The integration errors in the total electron population (296 electrons) are +0.0003 e(-) for the direct calculation (+0.0001%) and +0.0022 e(-) for KEM (+0.0007%). The accuracy of the KEM matrix elements is, thus, probably of the order of magnitude of the combined precision of the electronic structure calculation and the atomic integrations. KEM appears capable of delivering not only the total energies with chemical accuracy (which is well documented) but also local and nonlocal properties accurately, including the DIs between the fragments (crossing fragmentation lines). Matrices of the intact ribbon, the kernels, the KEM-reconstructed ribbon, and errors are available as Supporting Information . PMID:25343715

Timm, Matthew J; Matta, Chérif F; Massa, Lou; Huang, Lulu

2014-11-26

125

Early Response of Hepatic Malignancies to Locoregional Therapy—Value of Diffusion-Weighted Magnetic Resonance Imaging and Proton Magnetic Resonance Spectroscopy  

PubMed Central

Purpose The objective of our study was to determine the usefulness of the diffusion-weighted magnetic resonance imaging and proton magnetic resonance spectroscopy (1H-MRS) of hepatic malignancies for the assessment of response to locoregional treatment. Methods Forty-four patients (29 men; mean age, 58 years) with hepatic malignancies were treated locally. Magnetic resonance imaging examinations obtained before and at 1 and 6 months after transarterial chemoembolization were analyzed retrospectively. Imaging criteria included change in tumor size, percentage of enhancement in the arterial and portal venous phases, diffusion-weighted magnetic resonance imaging apparent diffusion coefficients, and choline concentration by quantitative 1H-MRS. Response to treatment was grouped according to RECIST (Response Evaluation Criteria in Solid Tumors) and European Association for the Study of the Liver (EASL) criteria based on magnetic resonance imaging at 6 months after treatment. Statistical analysis used paired t test, Fisher exact test, and univariate and multivariate Cox proportional hazards models. Results Before treatment, the median tumor diameter was 6 cm; at 6 months after treatment, median tumor diameter was 5.1 cm. According to RECIST and EASL, 66% of the patients achieved partial response, 31% had stable disease, and 3% of the patients showed progressive disease. One month after transarterial chemoembolization, apparent diffusion coefficient increased (P < 0.14), and mean choline concentration of the tumors decreased (P < 0.008). Conclusions Diffusion-weighted imaging and hepatic choline levels by 1H-MRS could predict response to locoregional therapy. PMID:21412085

Bonekamp, Susanne; Shen, Jialin; Salibi, Nouha; Lai, Hong C.; Geschwind, Jeff; Kamel, Ihab R.

2015-01-01

126

Proton Radiography at FAIR  

NASA Astrophysics Data System (ADS)

Proton radiography was invented in the 1990's at Los Alamos National Laboratory as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time a proton radiography facility has been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia. 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 für Schwerionenforschung (GSI) in Darmstadt, Germany. This new PRoton radIOgraphy facility at FAIR (PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a fundamental understanding of dynamic material properties at new length scales. These dynamic experiments will be driven with many energy sources including heavy ions, high explosives, guns and lasers. The capabilities of this new facility will be presented through a description of the first set of planned experiments.

Merrill, Frank; Golubev, Alexander; Turtikov, Vladmir; Varentsov, Dmitry

2009-06-01

127

Proton therapy in clinical practice  

PubMed Central

Radiation dose escalation and acceleration improves local control but also increases toxicity. Proton radiation is an emerging therapy for localized cancers that is being sought with increasing frequency by patients. Compared with photon therapy, proton therapy spares more critical structures due to its unique physics. The physical properties of a proton beam make it ideal for clinical applications. By modulating the Bragg peak of protons in energy and time, a conformal radiation dose with or without intensity modulation can be delivered to the target while sparing the surrounding normal tissues. Thus, proton therapy is ideal when organ preservation is a priority. However, protons are more sensitive to organ motion and anatomy changes compared with photons. In this article, we review practical issues of proton therapy, describe its image-guided treatment planning and delivery, discuss clinical outcome for cancer patients, and suggest challenges and the future development of proton therapy. PMID:21527064

Liu, Hui; Chang, Joe Y.

2011-01-01

128

MR-compatible ventilator for small animals: computer-controlled ventilation for proton and noble gas imaging  

E-print Network

MR-compatible ventilator for small animals: computer-controlled ventilation for proton and noble; accepted 28 April 2000 Abstract We describe an MR-compatible ventilator that is computer controlled, and to support delivery of gas anesthesia and experimental inhalational gases. A key feature of this ventilator

129

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

PubMed Central

Purpose A proton beam therapy (PBT) system has been designed which dedicates to spot-scanning and has a gating function employing the fluoroscopy-based real-time-imaging of internal fiducial markers near tumors. The dose distribution and treatment time of the newly designed real-time-image gated, spot-scanning proton beam therapy (RGPT) were compared with free-breathing spot-scanning proton beam therapy (FBPT) in a simulation. Materials and Methods In-house simulation tools and treatment planning system VQA (Hitachi, Ltd., Japan) were used for estimating the dose distribution and treatment time. Simulations were performed for 48 motion parameters (including 8 respiratory patterns and 6 initial breathing timings) on CT data from two patients, A and B, with hepatocellular carcinoma and with clinical target volumes 14.6 cc and 63.1 cc. The respiratory patterns were derived from the actual trajectory of internal fiducial markers taken in X-ray real-time tumor-tracking radiotherapy (RTRT). Results With FBPT, 9/48 motion parameters achieved the criteria of successful delivery for patient A and 0/48 for B. With RGPT 48/48 and 42/48 achieved the criteria. Compared with FBPT, the mean liver dose was smaller with RGPT with statistical significance (p<0.001); it decreased from 27% to 13% and 28% to 23% of the prescribed doses for patients A and B, respectively. The relative lengthening of treatment time to administer 3 Gy (RBE) was estimated to be 1.22 (RGPT/FBPT: 138 s/113 s) and 1.72 (207 s/120 s) for patients A and B, respectively. Conclusions This simulation study demonstrated that the RGPT was able to improve the dose distribution markedly for moving tumors without very large treatment time extension. The proton beam therapy system dedicated to spot-scanning with a gating function for real-time imaging increases accuracy with moving tumors and reduces the physical size, and subsequently the cost of the equipment as well as of the building housing the equipment. PMID:24747601

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

2014-01-01

130

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

131

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

SciTech Connect

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

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

2011-08-15

132

Proton Therapy  

MedlinePLUS

• Overview Protons are atoms that carry a positive charge. Just as x-rays (also known as photons) are used to treat both benign and malignant tumors, protons beams can be used to irradiate tumors in ...

133

Enantioselective Protonation  

PubMed Central

Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. These laboratory transformations have proven useful for the preparation of a number of valuable organic compounds. PMID:20428461

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

2010-01-01

134

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

E-print Network

alignment and verification procedures for proton beam radiation therapy. The quality of the image, both- generation proton CT scanner prototype, which is installed on the research beam line of the clinical proton of proton range estimates in radiation therapy planning have become a high priority. Protons

California at Santa Cruz, University of

135

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

Microsoft Academic Search

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

G. R. Hopkinson

1992-01-01

136

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

E-print Network

for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images room. Successful integration of pCT with proton therapy may lead to the ultimate form of image- guided on scattering a penetrating proton beam

137

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

PubMed Central

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

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

2012-01-01

138

Ring current proton precipitation as displayed by the proton aurora  

NASA Astrophysics Data System (ADS)

We review recent studies of precipitation of the ring current energetic protons based on obser-vations of proton aurora and direct measurements of energetic particle fluxes by low orbiting satellites. The proton aurora oval is formed by the precipitation of the plasma sheet and outer radiation belt protons scattered into the loss cone due to violation of their adiabatic motion in the region of weak magnetic field (e.g., in the equatorial plane of the nightside magneto-sphere). Equatorward of the proton oval, various detached proton aurora forms have been recently observed onboard the IMAGE spacecraft. The comparison of the sub-oval proton au-rora and electromagnetic ion-cyclotron (EMIC) wave observations in space and on the ground demonstrated that proton precipitation producing these auroras is the result of interaction of the ring current protons and EMIC waves. On the ground, EMIC waves are observed as ge-omagnetic pulsations of the Pc1 range. Different types of the sub-oval proton auroras (such as proton spots, evening-side proton arcs, proton flashes on the dayside) were found to be re-lated with different kinds of the Pc1 pulsations (such as "monochromatic Pc1" during quiet geomagnetic conditions, pulsations with diminishing periods during substorm injections, wide-band "Pc1 bursts" during magnetosphere compressions) representing different regimes of the ion-cyclotron interaction. Close spatial-temporal correlation between sub-oval proton auroras and EMIC waves means that the auroras visualize on the ionospheric "screen" the configuration of the magnetospheric region of the ion-cyclotron interaction and allow monitoring its dynam-ics. Furthermore, since the ion-cyclotron instability typically develops when the ring current particles contact the cold plasma the proton aurora observations provide a tool for monitoring the location of plasmapause and detached plasmaspheric structures.

Yahnin, Alexander

139

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

PubMed Central

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

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

2007-01-01

140

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  

Microsoft Academic Search

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)

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

2008-01-01

141

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

142

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

PubMed

The synergy between in-room imaging and optical tracking, in co-operation with highly accurate robotic patient handling represents a concept for patient-set-up which has been implemented at CNAO (Centro Nazionale di Adroterapia Oncologica). In-room imaging is based on a double oblique X-ray projection system; optical tracking consists of the detection of the position of spherical markers placed directly on the patient's skin or on the immobilization devices. These markers are used as external fiducials during patient positioning and dose delivery. This study reports the results of a comparative analysis between in-room imaging and optical tracking data for patient positioning within the framework of high-precision particle therapy. Differences between the optical tracking system (OTS) and the imaging system (IS) were on average within the expected localization accuracy. On the first 633 fractions for head and neck (H&N) set-up procedures, the corrections applied by the IS, after patient positioning using the OTS only, were for the mostly sub-millimetric regarding the translations (0.4 ± 1.1 mm) and sub-gradual regarding the rotations (0.0° ± 0.8°). On the first 236 fractions for pelvis localizations the amplitude of the corrections applied by the IS after preliminary optical set-up correction were moderately higher and more dispersed (translations: 1.3 ± 2.9 mm, rotations 0.1 ± 0.9°). Although the indication of the OTS cannot replace information provided by in-room imaging devices and 2D-3D image registration, the reported data show that OTS preliminary correction might greatly support image-based patient set-up refinement and also provide a secondary, independent verification system for patient positioning. PMID:23824116

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

2013-07-01

143

The association of trunk muscle cross-sectional area and magnetic resonance image parameters with isokinetic and psychophysical lifting strength and static back muscle endurance in men.  

PubMed

The relationship between trunk muscle morphology as measured on transverse magnetic resonance images and isokinetic lifting, psychophysical lifting, and static back muscle endurance testing was examined in 110 men, ages 35-67 years (mean, 48 years), who had been chosen based on their exposure to a wide variety of occupational and leisure-time physical activities. The computed T2-relaxation times and the T2-weighted and proton density-weighted signal intensities of the erector spinae, quadratus lumborum, and psoas major muscles had almost no association with any of the strength tests. The cross-sectional areas of the muscles had good correlations with isokinetic lifting strength (r = 0.46-0.53). They did not correlate well with psychophysical lifting and static back muscle endurance. Other characteristics or neurological or psychological factors may have more influence on those tests. PMID:9355056

Gibbons, L E; Latikka, P; Videman, T; Manninen, H; Battié, M C

1997-10-01

144

Experimental verification of proton beam monitoring in a human body by use of activity image of positron-emitting nuclei generated by nuclear fragmentation reaction  

Microsoft Academic Search

Proton therapy is a form of radiotherapy that enables concentration of dose on a tumor by use of a scanned or modulated Bragg\\u000a peak. Therefore, it is very important to evaluate the proton-irradiated volume accurately. The proton-irradiated volume can\\u000a be confirmed by detection of pair-annihilation gamma rays from positron-emitting nuclei generated by the nuclear fragmentation\\u000a reaction of the incident protons

Teiji Nishio; Aya Miyatake; Kazumasa Inoue; Tomoko Gomi-Miyagishi; Ryosuke Kohno; Satoru Kameoka; Keiichi Nakagawa; Takashi Ogino

2008-01-01

145

MR imaging of osteochondral grafts and autologous chondrocyte implantation  

PubMed Central

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible. PMID:16802126

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

2006-01-01

146

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

E-print Network

The synergy between in-room imaging and optical tracking, in co-operation with highly accurate robotic patient handling represents a concept for patient-set-up which has been implemented at CNAO (Centro Nazionale di Adroterapia Oncologica). In-room imaging is based on a double oblique X-ray projection system; optical tracking consists of the detection of the position of spherical markers placed directly on the patient’s skin or on the immobilization devices. These markers are used as external fiducials during patient positioning and dose delivery. This study reports the results of a comparative analysis between in-room imaging and optical tracking data for patient positioning within the framework of high-precision particle therapy. Differences between the optical tracking system (OTS) and the imaging system (IS) were on average within the expected localization accuracy. On the first 633 fractions for head and neck (H&N) set-up procedures, the corrections applied by the IS, after patient positioning usin...

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

2013-01-01

147

Proton Transport  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

148

Translational Approaches for Studying Neurodevelopmental Disorders Utilizing in Vivo Proton (+H) Magnetic Resonance Spectroscopic Imaging in Rats  

NASA Technical Reports Server (NTRS)

Intrauterine complications have been implicated in the etiology of neuripsychiatric disorders including schizophrenia, autism and ADHD. This presentation will describe new translational studies derived from in vivo magnetic resonance imaging of developing and adult brain following perinatal asphyxia (PA). Our findings reveal significant effects of PA on neurometabolic profiles at one week of age, and significant relationships between early metabolites and later life phenotypes including behavior and brain morphometry

Ronca, April E.

2014-01-01

149

Reconstruction with most likely trajectory for proton computed Tianfang Li*  

E-print Network

procedures for proton therapy, including xCT imaging, mapping of xCT numbers to proton stopping power values is absorbed in the body), pCT utilizes a high energy (100-250 MeV) proton beam, all of which penetrate throughReconstruction with most likely trajectory for proton computed tomography Tianfang Li* and Jerome

150

On proton CT reconstruction using MVCT-converted virtual proton projections  

SciTech Connect

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

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

2012-06-15

151

Statistical mapping of metabolites in the medial wall of the brain: A proton echo planar spectroscopic imaging study.  

PubMed

With magnetic resonance spectroscopic imaging (MRSI), it is possible to simultaneously map distributions of several brain metabolites with relatively good spatial resolution in a short time. Although other functional imaging modalities have taken advantage of population-based inferences using spatially extended statistics, this approach remains little utilized for MRSI. In this study, statistical nonparametric mapping (SnPM) was applied to two-dimensional MRSI data from the medial walls of the human brain to assess the effect of normal aging on metabolite concentrations. The effects of different preprocessing steps on these results were then explored. Short echo time MRSI of left and right medial walls was acquired in conjunction with absolute quantification of total choline, total creatine (tCr), glutamate and glutamine, myo-inositol, and N-acetyl-aspartate. Individual images were spatially warped to a common anatomical frame of reference. Age effects were assessed within SnPM as were the effects of voxel subsampling, variance smoothing, and spatial smoothing. The main findings were: (1) regions in the bilateral dorsal anterior cingulate and in the left posterior cingulate exhibited higher tCr concentrations with age; (2) voxel subsampling but not spatial smoothing enhanced the cluster-level statistical sensitivity; and (3) variance smoothing was of little benefit in this study. Our study shows that spatially extended statistics can yield information about regional-specific changes in metabolite concentrations obtained by short echo time MRSI. This opens up the possibility for systematic comparisons of metabolites in the medial wall of the brain. Hum Brain Mapp 36:852-861, 2015. © 2014 Wiley Periodicals, Inc. PMID:25338521

Niddam, David M; Tsai, Shang-Yueh; Lin, Yi-Ru

2015-03-01

152

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

PubMed Central

Introduction This work aimed to determine whether 1H magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are correlated with years of meditation and psychological variables in long-term Zen meditators compared to healthy non-meditator controls. Materials and Methods Design. Controlled, cross-sectional study. Sample. Meditators were recruited from a Zen Buddhist monastery. The control group was recruited from hospital staff. Meditators were administered questionnaires on anxiety, depression, cognitive impairment and mindfulness. 1H-MRS (1.5 T) of the brain was carried out by exploring four areas: both thalami, both hippocampi, the posterior superior parietal lobule (PSPL) and posterior cingulate gyrus. Predefined areas of the brain were measured for diffusivity (ADC) and fractional anisotropy (FA) by MR-DTI. Results Myo-inositol (mI) was increased in the posterior cingulate gyrus and Glutamate (Glu), N-acetyl-aspartate (NAA) and N-acetyl-aspartate/Creatine (NAA/Cr) was reduced in the left thalamus in meditators. We found a significant positive correlation between mI in the posterior cingulate and years of meditation (r?=?0.518; p?=?.019). We also found significant negative correlations between Glu (r?=??0.452; p?=?.045), NAA (r?=??0.617; p?=?.003) and NAA/Cr (r?=??0.448; P?=?.047) in the left thalamus and years of meditation. Meditators showed a lower Apparent Diffusion Coefficient (ADC) in the left posterior parietal white matter than did controls, and the ADC was negatively correlated with years of meditation (r?=??0.4850, p?=?.0066). Conclusions The results are consistent with the view that mI, Glu and NAA are the most important altered metabolites. This study provides evidence of subtle abnormalities in neuronal function in regions of the white matter in meditators. PMID:23536796

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

2013-01-01

153

Proton Radiotherapy  

NASA Astrophysics Data System (ADS)

Proton therapy is the most precise and advanced form of radiation treatment for cancer available. Due to the characteristic Bragg peak associated with ion energy deposition, proton therapy provides the radiation oncologist with a highly exact method of localizing treatment within a patient, as compared with conventional radiation therapy using X-rays or electrons. Controlling disease and minimizing side effects are the twin aims of radiation treatment; protons enhance the opportunity for both by facilitating maximal dose to tumor and minimal dose to surrounding tissue. In the United States, five proton centers currently treat cancer patients. Hampton Roads will be home to the nation's sixth, and largest. An overview of both the treatment capability and research planned for this center will be presented.

Keppel, Cynthia

2006-11-01

154

Proton therapy  

MedlinePLUS

... to treat the following types of cancer: Brain ( acoustic neuroma , childhood brain tumors ) Eye ( ocular melanoma , retinoblastoma ) ... to the tumor. The technician will leave the room while you are having proton therapy. The treatment ...

155

MR imaging of the Amide-Proton Transfer effect and the pH-insensitive Nuclear Overhauser Effect at 9.4 T  

PubMed Central

The amide proton transfer (APT) effect has emerged as a unique endogenous molecular imaging contrast mechanism with great clinical potentials. However, in vivo quantitative mapping of APT using the conventional asymmetry analysis is difficult due to the confounding Nuclear Overhauser Effect (NOE) and the asymmetry of the magnetization transfer (MT) effect. Here we showed that the asymmetry of MT contrast from immobile macromolecules is highly significant, and the wide spectral separation associated with a high magnetic field of 9.4 T delineates APT and NOE peaks in a Z-spectrum. Therefore, high resolution apparent APT and NOE maps can be obtained from measurements at three offsets. The apparent APT value was greater in gray matter compared to white matter in normal rat brain, and was sensitive to tissue acidosis and correlated well with ADC in the rat focal ischemic brain. In contrast, no ischemia-induced contrast was observed in the apparent NOE map. The concentration-dependence and the pH insensitivity of NOE were confirmed in phantom experiments. Our results demonstrate that in vivo apparent APT and NOE maps can be easily obtained at high magnetic fields, and the pH-insensitive NOE may be a useful indicator of mobile macromolecular contents. PMID:22577042

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

2012-01-01

156

Bi-exponential proton transverse relaxation rate (R2) image analysis using RF field intensity-weighted spin density projection: potential for R2 measurement of iron-loaded liver.  

PubMed

A bi-exponential proton transverse relaxation rate (R(2)) image analysis technique has been developed that enables the discrimination of dual compartment transverse relaxation behavior in systems with rapid transverse relaxation enhancement. The technique is particularly well suited to single spin-echo imaging studies where a limited number of images are available for analysis. The bi-exponential R(2) image analysis is facilitated by estimation of the initial proton spin density signal within the region of interest weighted by the RF field intensities. The RF field intensity-weighted spin density map is computed by solving a boundary value problem presented by a high spin density, long T(2) material encompassing the region for analysis. The accuracy of the bi-exponential R(2) image analysis technique is demonstrated on a simulated dual compartment manganese chloride phantom system with relaxation rates and relative population densities between the two compartments similar to the bi-exponential transverse relaxation behavior expected of iron loaded liver. Results from analysis of the phantoms illustrate the potential of bi-exponential R(2) image analysis with RF field intensity-weighted spin density projection for quantifying transverse relaxation enhancement as it occurs in liver iron overload. PMID:12878262

Clark, Paul R; Chua-anusorn, Wanida; St Pierre, Timothy G

2003-06-01

157

Magnetic Resonance Imaging Measurement Reproducibility for Calf Muscle and Adipose Tissue Volume  

PubMed Central

Purpose To describe a new semi-automated method for segmenting and measuring the volume of the muscle, bone and adipose (subcutaneous and inter-muscular) tissue in calf muscle compartments using magnetic resonance (MR) images and determine the intra- rater and inter-rater reproducibility of the measures. Materials and Methods Proton-density weighted MR images were acquired from the right calf for 21 subjects. Three raters segmented and measured the volumes of bones, adipose tissue, and 5 individual muscle compartments. Two raters repeated the segmentations. The intra- and inter-rater reproducibility of the measures (intra-class correlation coefficients; ICC) were determined using generalizability theory. Results All ICC values were greater than 0.96. The average SEM of all measures was 1.21 cm3 and none were greater than 2.3 cm3. Essentially all variation (? 97% for all measures) was due to subject differences indicating low error in the measurements. Conclusion The volumetric measurements for the bones, adipose tissue, and muscle in each of the compartments using MR imaging were highly reproducible. MR imaging can provide quantitative, reproducible volumetric measures of bone, adipose tissue, and individual muscles in the calf. We believe these methods can be used to quantify specific muscle or adipose volumetric measures for other clinical or research purposes. PMID:21964677

Commean, Paul K.; Tuttle, Lori J.; Hastings, Mary K.; Strube, Michael J; Mueller, Michael J.

2011-01-01

158

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. PMID:21598344

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

2013-01-01

159

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

Microsoft Academic Search

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

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

2003-01-01

160

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

Microsoft Academic Search

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

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

2002-01-01

161

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

E-print Network

We have investigated the radiation damage effects on a CCD to be employed in the Japanese X-ray astronomy mission including the Monitor of All-sky X-ray Image (MAXI) onboard the International Space Station (ISS). Since low energy protons release their energy mainly at the charge transfer channel, resulting a decrease of the charge transfer efficiency, we thus focused on the low energy protons in our experiments. A 171 keV to 3.91 MeV proton beam was irradiated to a given device. We measured the degradation of the charge transfer inefficiency (CTI) as a function of incremental fluence. A 292 keV proton beam degraded the CTI most seriously. Taking into account the proton energy dependence of the CTI, we confirmed that the transfer channel has the lowest radiation tolerance. We have also developed the different device architectures to reduce the radiation damage in orbit. Among them, the ``notch'' CCD, in which the buried channel implant concentration is increased, resulting in a deeper potential well than outside, has three times higher radiation tolerance than that of the normal CCD. We then estimated the charge transfer inefficiency of the CCD in the orbit of ISS, considering the proton energy spectrum. The CTI value is estimated to be 1.1e-5 per each transfer after two years of mission life in the worse case analysis if the highest radiation-tolerant device is employed. This value is well within the acceptable limit and we have confirmed the high radiation-tolerance of CCDs for the MAXI mission.

E. Miyata; T. Kamazuka; H. Kouno; M. Fukuda M. Mihara; K. Matsuta; H. Tsunemi; K. Tanaka; T Minamisono; H. Tomida; K. Miyaguchi

2002-08-26

162

[Fundamental study of the fat-suppressed three-dimensional coherent oscillatory state acquisition for the manipulation of image contrast (3D-COSMIC) sequence in the knee joint cartilage].  

PubMed

Fat-suppressed three-dimensional coherent oscillatory state acquisition for the manipulation of image contrast (3D-COSMIC) is a sequence that is based on fast imaging employing steady state acquisition (FIESTA) of balanced steady-state free precession (balanced SSFP). Since the data acquisition of steady-state transition is filled up with the center of k-space, improvement in the contrast of the cartilage, which is a low T?/T? value domain, is expected. This time we report on the usability in applying the above sequence to cartilage imaging of the knee joint and comparing and examining this sequence with the sequence in the past from the viewpoints of the contrast and scan time. As a result, compared with fat-suppressed three-dimensional spoiled gradient echo (3D-SPGR), the contrast of marrow and synovial fluid was equivalent to that of the cartilage, and imaging time was shorter than half of that with the cartilage. Compared with a fat-suppressed two-dimensional proton density weighted image (2D-PDWI), the contrast of the cartilage and synovial fluid was significantly improved, and spatial resolution was also excellent. As a short imaging time and a high resolution image pick-up are possible for fat-suppressed 3D-COSMIC, and it can describe minute damage of the cartilage since it depicts synovial fluid as high-level signals, I think this technique is useful. PMID:20975243

Amakawa, Takuya; Shinohe, Tooru; Tominaga, Satoru; Honda, Takashi; Fukumaru, Mitsuji; Sasaki, Jirou

2010-09-20

163

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

PubMed Central

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

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

2013-01-01

164

Proton radiobiology.  

PubMed

In addition to the physical advantages (Bragg peak), the use of charged particles in cancer therapy can be associated with distinct biological effects compared to X-rays. While heavy ions (densely ionizing radiation) are known to have an energy- and charge-dependent increased Relative Biological Effectiveness (RBE), protons should not be very different from sparsely ionizing photons. A slightly increased biological effectiveness is taken into account in proton treatment planning by assuming a fixed RBE of 1.1 for the whole radiation field. However, data emerging from recent studies suggest that, for several end points of clinical relevance, the biological response is differentially modulated by protons compared to photons. In parallel, research in the field of medical physics highlighted how variations in RBE that are currently neglected might actually result in deposition of significant doses in healthy organs. This seems to be relevant in particular for normal tissues in the entrance region and for organs at risk close behind the tumor. All these aspects will be considered and discussed in this review, highlighting how a re-discussion of the role of a variable RBE in proton therapy might be well-timed. PMID:25686476

Tommasino, Francesco; Durante, Marco

2015-01-01

165

Cosmic protons  

Microsoft Academic Search

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

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

2000-01-01

166

Proton geriatrics  

NASA Astrophysics Data System (ADS)

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

Kephart, Thomas W.; Nakagawa, Norio

1984-07-01

167

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

168

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

169

Design and construction of the 1st proton CT scanner  

NASA Astrophysics Data System (ADS)

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

Coutrakon, G.; Bashkirov, V.; Hurley, F.; Johnson, R.; Rykalin, V.; Sadrozinski, H.; Schulte, R.

2013-04-01

170

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

171

Proton Radiography Studies for Proton CT M. Petterson, N. Blumenkrantz, J. Feldt, J. Heimann, D. Lucia, A. Seiden, D. C. Williams, H. F.-W. Sadrozinski,  

E-print Network

. Randazzo, V. Sipala Abstract­We report the results of a beam experiment to develop proton Computed exploit the potentials of proton therapy because conversion of Hounsfield values measured with x tissues in the treatment room that could be minimized by using proton CT for image-guiding the proton beam

California at Santa Cruz, University of

172

Subauroral proton spots visualize the Pc1 source A. G. Yahnin,1  

E-print Network

, which is, most probably, due to pitch angle scattering of plasma sheet and outer radiation belt protonsSubauroral proton spots visualize the Pc1 source A. G. Yahnin,1 T. A. Yahnina,1 and H. U. Frey2 observations from the IMAGE spacecraft revealed a new type of proton aurora ­ subauroral proton spots, which

California at Berkeley, University of

173

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

174

Persistent global proton aurora caused by high solar wind dynamic pressure  

E-print Network

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

Bergen, Universitetet i

175

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

Microsoft Academic Search

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

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

2011-01-01

176

First results on proton radiography with nuclear emulsion detectors  

E-print Network

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

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

2010-01-01

177

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

178

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

179

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. PMID:20879574

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

2010-01-01

180

Proton Radioactivity Studies   

E-print Network

A search for new examples of proton emission from ground and low lying states was conducted at Argonne National Laboratory. Of particular interest were examples of proton emission from nuclei which were deformed or had an ...

Mahmud, Hassan A A

2002-01-01

181

New Proton Radioactivity   

E-print Network

A series of experiments were carried out at Argonne National Laboratory to search for examples of proton emission from ground and low­lying states in odd­Z nuclei at the proton drip­line. Recoils from fusion evaporation ...

Irvine, Richard J

1998-01-01

182

Proton pump inhibitors  

MedlinePLUS

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

183

What's In a Proton?  

ScienceCinema

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

Brookhaven Lab

2010-01-08

184

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

185

What's In a Proton?  

SciTech Connect

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

Brookhaven Lab

2009-07-08

186

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

187

Note: A new angle-resolved proton energy spectrometer  

SciTech Connect

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

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

2013-09-15

188

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. PMID:22178815

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

2011-01-01

189

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

PubMed

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

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

2014-10-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

191

Dynamic kine magnetic resonance imaging in whiplash patients and in age- and sex-matched controls.  

PubMed

The multitude of symptoms following a whiplash injury has given rise to much discussion because of the lack of objective radiological findings. The ligaments that stabilize the upper cervical spine can be injured. Dynamic kine magnetic resonance imaging (dMRI) may reveal the pathological motion patterns caused by injury to these ligaments. To compare the findings and motion patterns in the upper cervical spine, 25 whiplash trauma patients with longstanding pain, limb symptoms and loss of balance indicating a problem at the level of C0-C2, as well as matched healthy controls were imaged using dMRI. Imaging was performed with an Intera 1.5 T (Philips Healthcare, USA) magnet. A physiotherapist performed the bending and rotation of the upper cervical spine for the subjects to ensure that the movements were limited to the C0-C2 level. An oblique coronal T2- and proton density-weighted sequence and a balanced fast field echo axial sequence were used. The movements between C0-C2 and the signal from the alar ligaments were analyzed. Contact of the transverse ligament and the medulla in rotation was seen in two patients. The signal from the alar ligaments was abnormal in 92% of the patients and in 24% of the control subjects (P<0.0001). Abnormal movements at the level of C1-C2 were more common in patients than in controls (56% versus 20%, P=0.028). Whiplash patients with longstanding symptoms had both more abnormal signals from the alar ligaments and more abnormal movements on dMRI at the C0-C2 level than controls. PMID:20011712

Lindgren, Karl-August; Kettunen, J A; Paatelma, M; Mikkonen, R H M

2009-01-01

192

Images  

Cancer.gov

Images can be a powerful and direct means of communicating ideas and feelings about an organization and can create a personal connection with an audience. Imagery used for the main NCI website has been selected to give a consistent look throughout the site. Here are some recommended attributes for NCI website imagery.

193

High Power Proton Accelerators: Capabilities and  

E-print Network

neutron/fission 180 MeV/neutron Higher average neutron density. Spallation no chain reaction pulsed operation 30 neutrons/proton 30 Mev/neutron Higher peak neutron density. Getting Neutrons ­ Two Ways #12, CEMNET workshop 2007 Non-destructive analysis of a steel armed concrete block with neutron imaging and X

Tennessee, University of

194

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

195

Technical Note: evaluation of the uncertainties in (choline?+?creatine)/citrate ratios measured by proton MR spectroscopic imaging in patients suspicious for prostate cancer.  

PubMed

The presented evaluation of the relative uncertainty (?'CCC) of the (choline?+?creatine)/citrate (CC/C) ratios can provide objective information about the quality and diagnostic value of prostate MR spectroscopic imaging data. This information can be combined with the numeric values of CC/C ratios and provides metabolic-quality maps enabling accurate cancer detection and user-independent data evaluation. In addition, the prostate areas suffering most from the low precision of CC/C ratios (e.?g., prostate base) were identified. PMID:24940925

Zbý?, Š; Krššák, M; Memarsadeghi, M; Gholami, B; Haitel, A; Weber, M; Helbich, T H; Trattnig, S; Moser, E; Gruber, S

2014-07-01

196

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

SciTech Connect

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

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

2013-04-19

197

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

E-print Network

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

California at Berkeley, University of

198

UNIVERSITY of CALIFORNIA ENERGY LOSS OF PROTONS IN SILICON STRIP DETECTORS  

E-print Network

for their proton therapy patients. Researchers at the Santa Cruz Institute for Particle Physics have been commissioned to design and implement a prototype imaging solution that uses protons from the treatment beam Dedication vii Acknowledgements viii 1 Introduction 1 1.1 Characteristics of Proton Therapy

Belanger, David P.

199

A Detector for Proton Computed Tomography  

SciTech Connect

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

Blazey, G.; et al.,

2013-12-06

200

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

201

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

202

Single-proton spin detection by diamond magnetometry.  

PubMed

Extending magnetic resonance imaging to the atomic scale has been a long-standing aspiration, driven by the prospect of directly mapping atomic positions in molecules with three-dimensional spatial resolution. We report detection of individual, isolated proton spins by a nitrogen-vacancy (NV) center in a diamond chip covered by an inorganic salt. The single-proton identity was confirmed by the Zeeman effect and by a quantum coherent rotation of the weakly coupled nuclear spin. Using the hyperfine field of the NV center as an imaging gradient, we determined proton-NV distances of less than 1 nm. PMID:25323696

Loretz, M; Rosskopf, T; Boss, J M; Pezzagna, S; Meijer, J; Degen, C L

2014-10-16

203

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

PubMed Central

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

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

2014-01-01

204

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

PubMed

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

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

2014-04-01

205

Investigation of Proton Focusing and Conversion Efficiency for Proton Fast Ignition  

NASA Astrophysics Data System (ADS)

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

Bartal, Teresa Jean

206

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

207

Medical Applications: Proton Radiotherapy  

NASA Astrophysics Data System (ADS)

Proton therapy is a highly advanced and precise form of radiation treatment for cancer. Due to the characteristic Bragg peak associated with ion energy deposition, proton therapy provides the radiation oncologist with an improved method of treatment localization within a patient, as compared with conventional radiation therapy using X-rays or electrons. Controlling disease and minimizing side effects are the twin aims of radiation treatment. Proton beams enhance the opportunity for both by facilitating maximal dose to tumor and minimal dose to surrounding tissue. In the United States, five proton radiotherapy centers currently treat cancer patients, with more in the construction phase. New facilities and enabling technologies abound. An overview of the treatment modality generally, as well as of the capabilities and research planned for the field and for the Hampton University Proton Therapy Institute in particular, will be presented.

Keppel, Cynthia

2009-05-01

208

Electron-proton spectrometer  

NASA Technical Reports Server (NTRS)

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

Winckler, J. R.

1973-01-01

209

Proton-proton colliding beam facility ISABELLE  

SciTech Connect

This paper attempts to present the status of the ISABELLE construction project, which has the objective of building a 400 + 400 GeV proton colliding beam facility. The major technical features of the superconducting accelerators with their projected performance are described. Progress made so far, difficulties encountered, and the program until completion in 1986 is briefly reviewed.

Hahn, H

1980-01-01

210

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

E-print Network

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

California at Berkeley, University of

211

Proton magnetic resonance spectroscopy in multiple sclerosis  

SciTech Connect

Regional in vivo proton magnetic resonance spectroscopy provides quantitative data on selected chemical constituents of brain. We imaged 16 volunteers with clinically definite multiple sclerosis on a 1.5 tesla magnetic resonance scanner to define plaque-containing volumes of interest, and obtained localized water-suppressed proton spectra using a stimulated echo sequence. Twenty-five of 40 plaque-containing regions provided spectra of adequate quality. Of these, 8 spectra from 6 subjects were consistent with the presence of cholesterol or fatty acids; the remainder were similar to those obtained from white matter of normal volunteers. This early experience with regional proton spectroscopy suggests that individual plaques are distinct. These differences likely reflect dynamic stages of the evolution of the demyelinative process not previously accessible to in vivo investigation.

Wolinsky, J.S.; Narayana, P.A.; Fenstermacher, M.J. (Univ. of Texas Health Science Center, Houston (USA))

1990-11-01

212

Abstract --Advantages of proton computed tomography (pCT) have been recognized in the past. However, the quality of a pCT  

E-print Network

of the current tedious procedures for proton therapy, including xCT imaging, mapping of xCT numbers to protonCT utilizes a high energy (100-250 MeV) proton beam that penetrates the object. It is important of a conceptual pCT system. The proton pencil beam and detectors remain stationary while the object moves

Mueller, Klaus

213

Optimising the verification of patient positioning in proton beam therapy  

Microsoft Academic Search

A new patient positioning system incorporating a robotic arm is currently being designed for proton beam therapy. This requires aligning a treatment image with a pre-defined reference image. This is achieved by the alignment of the radiation and reference field boundaries, followed by registering the patient's anatomy relative to the boundary. This paper compares and tests methods for both field

T. M. Ransome; D. M. Rubin; T. Marwala; E. A. de Kock

2005-01-01

214

PROTON GYROMAGNETIC RATIO  

Microsoft Academic Search

The proton precession frequency has been measured in a 12-gauss magnetic ; field supplied by a precision solenoid. For protons in water the preliminary ; result obtained in terms of the NBS electrical standards is gamma \\/sub p\\/ = ; 2.67515 plus or minus 0.00001) x 10⁴ gauss⁻¹sec⁻¹, Benzene ; was found to give a result 1.9 plus or minus

R. L. Driscoll; P. L. Bender

1958-01-01

215

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

216

Feasibility of pulsed proton acoustics for 3D dosimetry  

NASA Astrophysics Data System (ADS)

Proton therapy has the potential to deposit its energy in tissue with high conformity to the tumor and significantly reduced integral dose to normal tissue compared to conventional radiation, such as x-rays. As a result, local control can be enhanced while reducing side-effects and secondary cancers. This is due to the way charged Particles deposit their energy or dose, where protons form a Bragg peak and establish a well-defined distal edge as a function of depth (range). To date, the dose delivered to a patient from proton therapy remains uncertain, in particular the positioning of the distal edge of the Bragg peak and the lateral displacement of the beam. The need for quality assurance methods to monitor the delivered dose during proton therapy, in particular intensity modulated proton therapy (IMPT) is critical. We propose to measure the acoustic signal generated from the deposited energy from ionizing radiation, in particular a proton beam; and to investigate the feasibility of ultrasound tomographic imaging to map the three dimensional dose (3D) dose from a proton pencil beam. A pulsed proton beam in water was simulated using Monte Carlo (MC) methods, and the pressure signal resulting from the deposited dose was simulated based on the thermoacoustics wave. A cylindrical scanner design with 71 ultrasound transducers focused to a centeral point within the scanner was utilized. Finally, a 3-D filtered backprojection algorithm was developed to reconstruct computed tomographic images of the deposited dose. The MC dose profile was compared to the radioacoustic reconstructed images, and the dependency of the proton pulse sequence parameters, pulse width (tPW) and rise time ( Delta t), on sensitivity were investigated. Based on simulated data, the reconstructed radioacoustic image intensity was within 2%, on average, of the MC generated dose within the Bragg peak, and the location of the distal edge was within 0.5mm. The simulated pressure signal for different tPW and Delta t for the same number of protons (1.8x107) demonstrated that compressing the protons in a shorter period of time significantly increased the thermoacoustic signal and thus sensitivity. This study demonstrates that computed tomographic scanner based on ionizing radiation induced acoustics can be used to verify dose distribution and proton range. Realizing this technology into the clinic will have significant impact on treatment verification during particle beam therapy and image guided techniques.

Alsanea, Fahed M.

217

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

218

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

NASA Astrophysics Data System (ADS)

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

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

2003-11-01

219

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

PubMed Central

Background Drought is a common stressor in many regions of the world and current climatic global circulation models predict further increases in warming and drought in the coming decades in several of these regions, such as the Mediterranean basin. The changes in leaf water content, distribution and dynamics in plant tissues under different soil water availabilities are not well known. In order to fill this gap, in the present report we describe our study withholding the irrigation of the seedlings of Quercus ilex, the dominant tree species in the evergreen forests of many areas of the Mediterranean Basin. We have monitored the gradual changes in water content in the different leaf areas, in vivo and non-invasively, by 1H magnetic resonance imaging (MRI) using proton density weighted (?w) images and spin-spin relaxation time (T2) maps. Results ?w images showed that the distal leaf area lost water faster than the basal area and that after four weeks of similar losses, the water reduction was greater in leaf veins than in leaf parenchyma areas and also in distal than in basal leaf area. There was a similar tendency in all different areas and tissues, of increasing T2 values during the drought period. This indicates an increase in the dynamics of free water, suggesting a decrease of cell membranes permeability. Conclusions The results indicate a non homogeneous leaf response to stress with a differentiated capacity to mobilize water between its different parts and tissues. This study shows that the MRI technique can be a useful tool to follow non-intrusively the in vivo water content changes in the different parts of the leaves during drought stress. It opens up new possibilities to better characterize the associated physiological changes and provides important information about the different responses of the different leaf areas what should be taken into account when conducting physiological and metabolic drought stress studies in different parts of the leaves during drought stress. PMID:20735815

2010-01-01

220

Jet energy measurement with the ATLAS detector in proton-proton collisions at sqrt(s) = 7 TeV  

E-print Network

The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of sqrt(s) = 7 TeV corresponding to an integrated luminosity of 38 inverse pb. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0.4 or R=0.6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pt > 20 GeV and pseudorapidities etajets with 60 jets with pt > 50 GeV after a dedicated correction for this effect. The JES is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pt, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pt jets recoiling against a high-pt jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, providing an improved jet energy resolution and a reduced flavour dependence of the jet response. The JES systematic uncertainty determined from a combination of in situ techniques are 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-pt jets.

ATLAS Collaboration

2011-12-29

221

High Temperature Protonic Conductors  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

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

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

224

Proton femtoscopy in STAR  

NASA Astrophysics Data System (ADS)

Two-particle femtoscopy allows one to study the properties of matter created in heavy ion collisions. It makes the study of space-time evolution of the source possible and may be applied to many different combinations of hadron pairs. Two-proton femtoscopy enables to extract the radii of produced sources which, compared to those obtained from pion studies, provide additional information about source characteristics. In this paper we present the correlation functions obtained for protons and antiprotons for Au + Au collisions at ?sNN = 200 GeV.

Zbroszczyk, Hanna

2014-04-01

225

Proton irradiation and endometriosis  

SciTech Connect

It was found that 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 determined to be 7 years after the proton exposure. The doses and energies of the radiation received by the experimental animals were within the range that could be received by an aircrew member in near-earth orbit during a random solar flare event. It is concluded that endometriosis should be a consideration in assessing the risk of delayed radiation effects in female crew members. 15 references.

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

1983-08-01

226

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

PubMed

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

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

2013-11-21

227

Predictions of diffractive cross sections in proton-proton collisions  

SciTech Connect

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

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

2013-04-15

228

Three new defined proton affinities for polybasic molecules in the gas-phase: Proton microaffinity, proton macroaffinity and proton overallaffinity  

NASA Astrophysics Data System (ADS)

A theoretical study on complete protonation of a series of tetrabasic molecules with general formula N[(CH 2) nNH 2][(CH 2) mNH 2][(CH 2) pNH 2] (tren, pee, ppe, tpt, epb and ppb) is reported. For first time, three kinds of gas-phase proton affinities for each polybasic molecule are defined as: 'proton microaffinity (PA n, i)', 'proton macroaffinity (PA)' and 'proton overall affinity ( PA)'. The variations of calculated logPA in the series of these molecules is very similar to that of their measured log Kn. There is also a good correlation between the calculated gas-phase proton macroaffinities and proton overallaffinities with corresponding equilibrium macroconstants and overall protonation constants in solution.

Salehzadeh, Sadegh; Bayat, Mehdi

2006-08-01

229

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

230

Spinning Electrons and Protons  

Microsoft Academic Search

THE remarkable results obtained within the past fifteen months by employing the spinning electron in Bohr's atomic model suggest the question whether it may not be necessary to suppose that the proton also is capable of a quantised spin. Although the analytical difficulties in applying the new quantum mechanics to this problem may be considerable, they may not be too

H. S. Allen

1927-01-01

231

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

232

The proton (nuclear) microprobe  

Microsoft Academic Search

The scanning proton microprobe (SPMP) is closely related to the scanning electron microprobe (SEMP) or scanning electron microscope (SEM) with X-ray detector. Though the much greater elemental sensitivity of the SPMP is inherent in the physics, the generally inferior spatial resolution of the SPMP is not inherent and big improvements are possible, As its alternative name would imply, the SPMP

G. J. F. Legge

1989-01-01

233

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

234

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

235

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

2013-10-21

236

Folding model analysis of proton radioactivity of spherical proton emitters  

E-print Network

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

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

2005-11-17

237

An empirical determination of proton auroral far ultraviolet emission efficiencies using a new nonclimatological proton flux extrapolation method  

NASA Astrophysics Data System (ADS)

Model-derived electron and proton auroral FUV emission efficiencies of relevance to auroral FUV remote sensing methods are evaluated using coincident observations by Special Sensor Ultraviolet Spectrographic Imager (SSUSI) and Special Sensor J/5 (SSJ/5), both on board the Defense Meteorological Satellite Program (DMSP) satellite F16. This follows earlier work by Knight et al. (2008), which reported higher than expected proton Lyman-Birge-Hopfield (LBH) emission efficiencies based on F16 SSUSI and SSJ/5 comparisons, and Correira et al. (2011), which suggested a downward revision in the proton LBH efficiencies from Knight et al. (2008). These proton efficiency results rely on proton extrapolation methods to supply the unmeasured proton flux above 30 keV (the upper limit of SSJ/5). Correira et al. (2011) determined that there was a bias in the proton extrapolation method used by Knight et al. (2008) that was caused by column emission rate (CER) thresholding in the coincident SSUSI and SSJ/5 sets. In the latest work, a more robust proton flux extrapolation method is introduced which does not have the problem of CER threshold dependence. The new extrapolation method uses coincident SSUSI Lyman alpha observations to constrain the extrapolated proton flux above 30 keV in such a way that unknown Lyman alpha model yield errors and SSUSI and SSJ/5 calibration errors drop out without biasing the extrapolation. With the latest extrapolation method, SSUSI-SSJ/5 comparisons indicate that proton aurora is typically a factor of ˜4.5 more efficient per unit of energy flux in producing LBH than electron aurora.

Knight, H. K.; Strickland, D. J.; Correira, J.; Hecht, J. H.; Straus, P. R.

2012-11-01

238

Three new defined proton affinities for polybasic molecules in the gas-phase: Proton microaffinity, proton macroaffinity and proton overallaffinity  

Microsoft Academic Search

A theoretical study on complete protonation of a series of tetrabasic molecules with general formula N[(CH2)nNH2][(CH2)mNH2][(CH2)pNH2] (tren, pee, ppe, tpt, epb and ppb) is reported. For first time, three kinds of gas-phase proton affinities for each polybasic molecule are defined as: ‘proton microaffinity (PAn,i)’, ‘proton macroaffinity (PA¯n)’ and ‘proton overall affinity (PA¯ov)’. The variations of calculated logPA¯n in the series

Sadegh Salehzadeh; Mehdi Bayat

2006-01-01

239

Study of 1 Megaton water Cherenkov detectors for the future proton decay search  

E-print Network

Study of 1 Megaton water Cherenkov detectors for the future proton decay search M. Shiozawa #3­1205, JAPAN Abstract. The sensitivity of a possible future 1 Megaton water Cherenkov detector for proton decay is a ring imaging Cherenkov detector with a target of water; Kamiokande, IMB, and Super­Kamiokande (SK

Tokyo, University of

240

Study of 1 Megaton water Cherenkov detectors for the future proton decay search  

E-print Network

Study of 1 Megaton water Cherenkov detectors for the future proton decay search M. Shiozawa-1205, JAPAN Abstract. The sensitivity of a possible future 1 Megaton water Cherenkov detector for proton decay imaging Cherenkov detector with a target of water; Kamiokande, IMB, and Super-Kamiokande (SK), and another

Tokyo, University of

241

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

Microsoft Academic Search

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

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

2007-01-01

242

The Eindhoven proton microbeam  

NASA Astrophysics Data System (ADS)

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

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

1981-03-01

243

Proton therapy for sarcomas.  

PubMed

Sarcomas are a heterogeneous group of tumors that can occur in a wide array of anatomic sites and age ranges with varying histologies. Proton beam therapy, as compared with advanced x-ray radiation therapy techniques, can substantially lower dose to nontarget tissues. This dosimetric advantage can potentially allow for improvement of the therapeutic ratio in the treatment of many of the sarcomas by either increasing the local control, via increased dose to the target, or by decreasing the normal tissue complications, via lowered dose to the avoidance structures. This article reviews the key dosimetric studies and clinical outcomes published to date documenting the potential role proton beam therapy may play in the treatment of sarcomas. PMID:25415687

Keole, Sameer; Ashman, Jonathan B; Daniels, Thomas B

2014-01-01

244

Ocular Proton Therapy Centers  

NASA Astrophysics Data System (ADS)

This chapter describes a review of proton therapy (PT) centers and the techniques used for the treatment of ocular lesions. The role of ion beam therapy (IBT) for eye treatments, principally choroidal melanomas, has become well established among the competing treatment modalities. More national centers now offer PT for these lesions, but not necessarily in a hospital environment. Significant improvements in eye treatment planning, patient positioning, and QA dosimetry have been realized, to the benefit of treatment efficiency and accuracy of dose delivery.

Kacperek, Andrzej

245

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

NASA Technical Reports Server (NTRS)

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

Norbury, John W.; Blattnig, Steve R.

2008-01-01

246

"Decoupled" Proton NMR Spectra  

NASA Astrophysics Data System (ADS)

High-resolution proton NMR spectra are recorded in a new form where all resonances are singlets at the chemical-shift frequencies, with no spin-spin splittings. These "decoupled" proton spectra are derived from two-dimensional J spectra after real Fourier transformation (without frequency discrimination in F1) so that each spin multiplet lies along both the 45° and the 135° diagonal, forming a pattern similar to St. Andrew's cross, with C 4 symmetry. The chemical shifts are located by searching for these centers of symmetry with a postacquisition data-processing algorithm. This is designed to facilitate the separation of overlapping and interpenetrating spin multiplets. The method is illustrated with applications to the 400 MHz high-resolution proton spectra of dehydrotestosterone and 4-androsten-3,17-dione. It is also possible to separate the spectra of components in a mixture and this is illustrated by breaking down the spectrum of an aqueous solution of D-glucose into subspectra from the ? and ? anomers, in order to follow the time evolution of the mutarotation.

Woodley, M.; Freeman, R.

247

Ionospherically reflected proton whistlers  

NASA Astrophysics Data System (ADS)

We present experimental observations and detailed investigation of the variety of proton whistlers that includes transequatorial and ionospherically reflected proton whistlers. The latter have previously been indicated from numerical modeling of spectrograms. The study is based on six-component ELF wave data from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite which permits to obtain not only spectrograms displaying the power spectral density but also such wave properties as the polarization, wave normal angle, wave refractive index, and normalized parallel component of the Poynting vector. The explanation of various types of proton whistlers is based on the properties of ion cyclotron wave propagation in a multicomponent magnetoplasma, with special consideration of the effect of ion hybrid resonance reflection. Analysis of experimental data is supplemented by numerical modeling of spectrograms that reproduces the main features of experimental ones. As a self-contained result, we provide conclusive experimental evidences that the region illuminated by a lightning stroke in the Earth-ionosphere waveguide may spread over a distance of 4000 km in both hemispheres.

Vavilov, D. I.; Shklyar, D. R.

2014-12-01

248

Differential Cross Sections for Proton-Proton Elastic Scattering  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

249

Structural Investigation of Protonated Azidothymidine and Protonated Dimer  

NASA Astrophysics Data System (ADS)

Infrared multiple photon dissociation (IRMPD) spectroscopy experiments and quantum chemical calculations have been used to explore the possible structures of protonated azidothymidine and the corresponding protonated dimer. Many interesting differences between the protonated and neutral forms of azidothymidine were found, particularly associated with keto-enol tautomerization. Comparison of computational vibrational and the experimental IMRPD spectra show good agreement and give confidence that the dominant protonated species has been identified. The protonated dimer of azidothymidine exhibits three intramolecular hydrogen bonds. The IRMPD spectrum of the protonated dimer is consistent with the spectrum of the most stable computational structure. This work brings to light interesting keto-enol tautomerization and exocyclic hydrogen bonding involving azidothymidine and its protonated dimer. The fact that one dominant protonated species is observed in the gas phase, despite both the keto and enol structures being similar in energy, is proposed to be the direct result of the electrospray ionization process in which the dominant protonated dimer structure dissociates in the most energetically favorable way.

Ziegler, Blake E.; Marta, Rick A.; Burt, Michael B.; Martens, Sabrina M.; Martens, Jonathan K.; McMahon, Terry B.

2013-12-01

250

Structural investigation of protonated azidothymidine and protonated dimer.  

PubMed

Infrared multiple photon dissociation (IRMPD) spectroscopy experiments and quantum chemical calculations have been used to explore the possible structures of protonated azidothymidine and the corresponding protonated dimer. Many interesting differences between the protonated and neutral forms of azidothymidine were found, particularly associated with keto-enol tautomerization. Comparison of computational vibrational and the experimental IMRPD spectra show good agreement and give confidence that the dominant protonated species has been identified. The protonated dimer of azidothymidine exhibits three intramolecular hydrogen bonds. The IRMPD spectrum of the protonated dimer is consistent with the spectrum of the most stable computational structure. This work brings to light interesting keto-enol tautomerization and exocyclic hydrogen bonding involving azidothymidine and its protonated dimer. The fact that one dominant protonated species is observed in the gas phase, despite both the keto and enol structures being similar in energy, is proposed to be the direct result of the electrospray ionization process in which the dominant protonated dimer structure dissociates in the most energetically favorable way. PMID:24306778

Ziegler, Blake E; Marta, Rick A; Burt, Michael B; Martens, Sabrina M; Martens, Jonathan K; McMahon, Terry B

2014-02-01

251

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

PubMed

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

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

2013-11-01

252

Proton irradiation and endometriosis  

SciTech Connect

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.

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

1983-08-01

253

Proton Upset Monte Carlo Simulation  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

254

Proton Beam Focusing and Heating in Petawatt Laser-Solid Interactions  

SciTech Connect

It has recently been demonstrated that femtosecond-laser generated proton beams may be focused. These protons, following expansion of the Debye sheath, emit off the inner concave surface of hemispherical shell targets irradiated at their outer convex pole. The sheath normal expansion produces a rapidly converging proton beam. Such focused proton beams provide a new and powerful means to achieve isochoric heating to high temperatures. They are potentially important for measuring the equation of state of materials at high energy density and may provide an alternative route to fast ignition. We present the first results of proton focusing and heating experiments performed at the Petawatt power level at the Gekko XII Laser Facility at ILE Osaka Japan. Solid density Aluminum slabs are placed in the proton focal region at various lengths. The degree of proton focusing is measured via XUV imaging of Planckian emission of the heated zone. Simultaneous with the XUV measurement a streaked optical imaging technique, HISAK, gave temporal optical emission images of the focal region. Results indicate excellent coupling between the laser-proton conversion and subsequent heating.

Snavely, R A; Gu, P; King, J; Hey, D; Akli, K; Zhang, B B; Freeman, R; Hatchett, S; Key, M H; Koch, J; Langdon, A B; Lasinsky, B; MacKinnon, A; Patel, P; Town, R; Wilks, S; Stephens, R; Tsutsumi, T; Chen, Z; Yabuuchi, T; Kurahashi, T; Sato, T; Adumi, K; Toyama, Y; Zheng, J; Kodama, R; Tanaka, K A; Yamanaka, T

2003-08-13

255

First tests for an online treatment monitoring system with in-beam PET for proton therapy  

E-print Network

PET imaging is a non-invasive technique for particle range verification in proton therapy. It is based on measuring the beta+ annihilations caused by nuclear interactions of the protons in the patient. In this work we present measurements for proton range verification in phantoms, performed at the CNAO particle therapy treatment center in Pavia, Italy, with our 10 x 10 cm^2 planar PET prototype DoPET. PMMA phantoms were irradiated with mono-energetic proton beams and clinical treatment plans, and PET data were acquired during and shortly after proton irradiation. We created 1-D profiles of the beta+ activity along the proton beam-axis, and evaluated the difference between the proximal rise and the distal fall-off position of the activity distribution. A good agreement with FLUKA Monte Carlo predictions was obtained. We also assessed the system response when the PMMA phantom contained an air cavity. The system was able to detect these cavities quickly after irradiation.

Kraan, Aafke C; Belcari, N; Camarlinghi, N; Cappucci, F; Ciocca, M; Ferrari, A; Ferretti, S; Mairani, A; Molinelli, S; Pullia, M; Retico, A; Sala, P; Sportelli, G; Del Guerra, A; Rosso, V

2014-01-01

256

First tests for an online treatment monitoring system with in-beam PET for proton therapy  

NASA Astrophysics Data System (ADS)

PET imaging is a non-invasive technique for particle range verification in proton therapy. It is based on measuring the ?+ annihilations caused by nuclear interactions of the protons in the patient. In this work we present measurements for proton range verification in phantoms, performed at the CNAO particle therapy treatment center in Pavia, Italy, with our 10 × 10 cm2 planar PET prototype DoPET. PMMA phantoms were irradiated with mono-energetic proton beams and clinical treatment plans, and PET data were acquired during and shortly after proton irradiation. We created 1-D profiles of the ?+ activity along the proton beam-axis, and evaluated the difference between the proximal rise and the distal fall-off position of the activity distribution. A good agreement with FLUKA Monte Carlo predictions was obtained. We also assessed the system response when the PMMA phantom contained an air cavity. The system was able to detect these cavities quickly after irradiation.

Kraan, A. C.; Battistoni, G.; Belcari, N.; Camarlinghi, N.; Cappucci, F.; Ciocca, M.; Ferrari, A.; Ferretti, S.; Mairani, A.; Molinelli, S.; Pullia, M.; Retico, A.; Sala, P.; Sportelli, G.; Del Guerra, A.; Rosso, V.

2015-01-01

257

The Rate of the Proton-Proton Reaction  

E-print Network

We re-evaluate the matrix element for the proton-proton reaction which is important for stellar-evolution calculations and for the solar-neutrino problem. We self-consistently determine the effect of vacuum polarization on the matrix element by first correcting the low-energy scattering data to account for vacuum polarization. We then calculate the proton-proton wave function by integrating the Schrodinger equation with vacuum polarization included. We use improved data for proton-proton scattering and for the deuteron wave function. We evaluate the uncertainties that are due to experimental error and estimate those that are due to theoretical inadequacies. We estimate the theoretical uncertainty by using six different deuteron potentials and five different proton-proton potentials. Vacuum polarization decreases the calculated value by $0.6_{-0.4}^{+0.1}$\\%. The complete result is $\\Lambda^2=6.92\\times(1\\pm0.002^{+0.014}_{-0.009})$ where the first uncertainty is due to experimental errors and the second uncertainty is due to theoretical uncertainties. Our value of $\\Lambda^2$ is 2\\% smaller than the value obtained in 1969 by Bahcall and May. The improved calculations of the rate of the $pp$ reaction described here increase slightly the predicted event rates for the chlorine and the Kamiokande solar-neutrino experiments.

Marc Kamionkowski; John N. Bahcall

1993-06-24

258

Proton in SRF Niobium  

SciTech Connect

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

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

2011-03-31

259

Parameterizations of Inclusive Cross Sections for Kaon, Proton, and Antiproton Production in Proton-Proton Collisions  

NASA Astrophysics Data System (ADS)

Inclusive kaon, proton, and antiproton production from high-energy proton-proton collisions is studied. Various available parameterizations of Lorentz-invariant, differential cross sections, as a function of transverse momentum and rapidity, are compared with experimental data. This paper shows that the Badhwar parameterization provides the best fit for charged kaon production. For proton production, the Alper parameterization is best and for antiproton production the Carey parameterization works best. The formulae for these cross sections are suitable for use in high-energy cosmic ray transport codes.

Norbury, John W.

2009-05-01

260

Electron-screening correction for the proton-proton reaction John N. Bahcall*  

E-print Network

Electron-screening correction for the proton-proton reaction John N. Bahcall* School of Natural screening of the solar proton-proton fusion reaction by solving numerically the relevant Schro-Huckel screening potential, for the fundamental proton-proton (pp) reaction. The unscreened rate of this reaction

Bahcall, John

261

Proton Radiography Peers into Metal Solidification  

PubMed Central

Historically, metals are cut up and polished to see the structure and to infer how processing influences the evolution. We can now peer into a metal during processing without destroying it using proton radiography. Understanding the link between processing and structure is important because structure profoundly affects the properties of engineering materials. Synchrotron x-ray radiography has enabled real-time glimpses into metal solidification. However, x-ray energies favor the examination of small volumes and low density metals. Here we use high energy proton radiography for the first time to image a large metal volume (>10,000?mm3) during melting and solidification. We also show complementary x-ray results from a small volume (<1?mm3), bridging four orders of magnitude. Real-time imaging will enable efficient process development and the control of structure evolution to make materials with intended properties; it will also permit the development of experimentally informed, predictive structure and process models. PMID:23779063

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

2013-01-01

262

Proton Collimators for Fusion Reactors  

NASA Technical Reports Server (NTRS)

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

Miley, George H.; Momota, Hiromu

2003-01-01

263

Quark spin in the proton  

E-print Network

The proton spin puzzle has challenged our understanding of QCD for the last 20 years. We survey new developments in theory and experiment. The proton spin puzzle seems to be telling us about the interplay of valence quarks with chiral dynamics and the complex vacuum structure of QCD.

Bass, Steven D

2010-01-01

264

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

265

CANCER IMAGING: Instrumentation and Application. Volume 2. Edited by M.A. Hayat. Page 3-16. ELSEVIER: Academic Press is an imprint of Elsevier, New York, 2008 1 of 39  

E-print Network

to be imaged. The potential of pCT in medicine relies mainly on its role in improving proton beam therapy. Proton beams have distinct advantages compared to other radiation therapy options, such as X- rays photons and protons, which partially obviates the advantage of proton therapy. Using proton beam

266

The proton (nuclear) microprobe  

NASA Astrophysics Data System (ADS)

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

Legge, G. J. F.

1989-04-01

267

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

E-print Network

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

Kok, Trina

2012-01-01

268

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

269

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

270

Mapping the Proton's Fluctuating Waistline  

E-print Network

We discuss a mechanism for the apparently universal scaling in the high-multiplicity tail of charged particle distributions for high energy nuclear collisions. We argue that this scaling behavior originates from rare fluctuations of the nucleon density. We discuss a pair of simple models of proton shape fluctuations. A "fat" proton with a size of 3 fm occurs with observable frequency. In light of this result, collective flow behavior in the ensuing nuclear interaction seems feasible. We discuss the influence of these models on the large $x$ structure of the proton and the likely influences on the distribution of initial state spatial eccentricities $\\epsilon_{n}$.

Coleman-Smith, Christopher E

2014-01-01

271

Proton and Neutrino Extragalactic Astronomy  

E-print Network

The study of extragalactic sources of high energy radiation via the direct measurement of the proton and neutrino fluxes that they are likely to emit is one of the main goals for the future observations of the recently developed air showers detectors and neutrino telescopes. In this work we discuss the relation between the inclusive proton and neutrino signals from the ensemble of all sources in the universe, and the resolved signals from the closest and brightest objects. We also compare the sensitivities of proton and neutrino telescopes and comment on the relation between these two new astronomies.

Paolo Lipari

2008-08-04

272

Protonation effect on drug affinity.  

PubMed

Pharmacologic ligand-macromolecule interactions are commonly characterized by affinity (dissociation) constants such as K(d) or K(i) without regard to the protonation effect of the buffer used in the measurement. The protonation effect is demonstrated here using isothermal titration microcalorimetry measurements of the competitive inhibitor binding of cytidine 2'-monophosphate (2'-CMP) to RNase-A as a model system in buffers of different ionization Delta H(buffer). The results demonstrate the importance of protonation in measures of affinity. PMID:14729124

Raffa, Robert B; Stagliano, Gregory W; Spencer, Shawn D

2004-01-12

273

RHIC Polarized proton operation  

SciTech Connect

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

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

2011-03-28

274

Eta Meson Production in Proton-Proton and Nuclear Collisions  

NASA Technical Reports Server (NTRS)

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

Norbury, John W.; Dick, Frank

2008-01-01

275

Testing of radiation detectors by IBIC imaging  

Microsoft Academic Search

The nuclear microprobe technique IBIC (Ion Beam Induced Charge) was used for tests of different radiation detectors. By using a 2–6 MeV proton microbeam with a current of less than 1000 protons per second, images and profiles of charge collection efficiency in radiation detectors can be produced. This application of the IBIC technique provides results that can be used to

M. JaksiC; I. Bogdanovi?; M. Bogovac; S. Fazini?; S. Galassini; K. Kova?evi?; C. Manfredotti; E. Vittone

1996-01-01

276

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

277

Fetal imaging by nuclear magnetic resonance: a study in goats: work in progress  

SciTech Connect

Nuclear magnetic resonance proton imaging was used to obtain images of goat fetuses in utero. The long T1 relaxation time of amniotic fluid makes it appear black on proton density images when examined using the Aberdeen imager, and so allows very good discrimination of the position and structure of the fetus. Some fetal internal tissues can be seen on T1 images. These findings suggest that NMR imaging has great potential in pregnancy studies.

Foster, M.A. (Univ. of Aberdeen, Scotland); Knight, C.H.; Rimmington, J.E.; Mallard, J.R.

1983-10-01

278

The physics of Cerenkov light production during proton therapy  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

279

The physics of Cerenkov light production during proton therapy.  

PubMed

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

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

2014-12-01

280

Emerging technologies in proton therapy.  

PubMed

An increasing number of proton therapy facilities are being planned and built at hospital based centers. Most facilities are employing traditional dose delivery methods. A second generation of dose application techniques, based on pencil beam scanning, is slowly being introduced into the commercially available proton therapy systems. New developments in accelerator physics are needed to accommodate and fully exploit these new techniques. At the same time new developments such as the development of small cyclotrons, Dielectric Wall Accelerator (DWA) and laser driven systems, aim for smaller, single room treatment units. In general the benefits of proton therapy could be exploited optimally when achieving a higher level in accuracy, beam energy, beam intensity, safety and system reliability. In this review an overview of the current developments will be given followed by a discussion of upcoming new technologies and needs, like increase of energy, on-line MRI and proton beam splitting for independent uses of treatment rooms. PMID:21767183

Schippers, Jacobus M; Lomax, Antony J

2011-08-01

281

High-energy solar protons  

NASA Astrophysics Data System (ADS)

Evidence is presented for a second particle acceleration phase following the explosive phase of a solar flare. Cerenkov and scintillation counters were employed on the Prognoz satellite to detect the arrival of protons with energies greater than 100 MeV or 500 MeV, respectively. Delays of several minutes to several tens of minutes were observed for the arrival of protons from radiobursts in the cm range and X ray bursts during solar flare activity. A similar delay was recorded on the Proton-3 satellite during a burst event of Nov. 22, 1977, using the same measurement techniques. The existence of a second acceleration phase, when protons are accelerated to high energies and electrons up to relativistic energies, is noted to not contradict a model of the explosive phase of the flare as a process of disappearance and break of the current layer in the region of a highly dense plasma

Volodichev, N. N.; Savenko, I. A.

282

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

283

Curvature Radiation by Ultrarelativistic Protons  

E-print Network

We study pion curvature radiation by a proton, i.e. pion emission by a proton moving along a curved trajectory. We suggest an approximate semiclassical solution and the exact solution for which we assume that a proton moves in a fictitious magnetic field with the Larmor radius equal to the curvature radius of the real trajectory. As possible application we consider the pion radiation by ultrahigh energy protons moving along curved magnetic field lines. Such situation can occur in the magnetosphere of a young pulsar, in the magnetosphere of the accretion disk around a black hole, and in the vicinity of a superconducting cosmic string. The decay products of these pions, such as high energy photons or neutrinos, can give the observable consequences of the considered mechanism.

V. Berezinsky; A. Dolgov; M. Kachelriess

1995-04-05

284

3, 17331752, 2003 Solar proton  

E-print Network

; Jackman et al., 1990, 2001). They also have nucleonic effects by which they can almost instantaneously (mainly from high energy protons) forms the basis for the widely applied radiocarbon dating (Libby, 1952

Paris-Sud XI, Université de

285

Proton Radiotherapy for Pediatric Sarcoma  

PubMed Central

Pediatric sarcomas represent a distinct group of pathologies, with approximately 900 new cases per year in the United States alone. Radiotherapy plays an integral role in the local control of these tumors, which often arise adjacent to critical structures and growing organs. The physical properties of proton beam radiotherapy provide a distinct advantage over standard photon radiation by eliminating excess dose deposited beyond the target volume, thereby reducing both the dose of radiation delivered to non-target structures as well as the total radiation dose delivered to a patient. Dosimetric studies comparing proton plans to IMRT and 3D conformal radiation have demonstrated the superiority of protons in numerous pediatric malignancies and data on long-term clinical outcomes and toxicity is emerging. In this article, we review the existing clinical and dosimetric data regarding the use of proton beam radiation in malignant bone and soft tissue sarcomas. PMID:24424260

Ladra, Matthew M.; Yock, Torunn I.

2014-01-01

286

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

287

Diffusion across proton collecting surfaces Noam Agmon *  

E-print Network

­Kimball ``radiation boundary condition" [19]. Proton collecting sites which are saturable. To achieveDiffusion across proton collecting surfaces Noam Agmon * The Fritz Haber Research Center, Institute: Diffusion Proton collecting surface Steady-state rate a b s t r a c t A model for a proton collecting

Agmon, Noam

288

Computing proton dose to irregularly moving targets  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

289

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

290

Voltage-gated Proton Channels  

PubMed Central

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

DeCoursey, Thomas E.

2014-01-01

291

Recent Solar-Proton Fluxes  

NASA Technical Reports Server (NTRS)

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

Reedy, R. C.

2005-01-01

292

Proton aurora and substorm intensifications  

Microsoft Academic Search

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

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

1992-01-01

293

Proton beam monitor chamber calibration.  

PubMed

The first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic proton beam. For the latter, this paper also compares two independent dosimetry techniques to calibrate the beam monitor chambers: absolute dosimetry (of the number of protons exiting the nozzle) with a Faraday cup and reference dosimetry (i.e. determination of the absorbed dose to water under IAEA TRS-398 reference conditions) with an ionization chamber. To compare the two techniques, Monte Carlo simulations were performed to convert dose-to-water to proton fluence. A good agreement was found between the Faraday cup technique and the reference dosimetry with a plane-parallel ionization chamber. The differences-of the order of 3%-were found to be within the uncertainty of the comparison. For cylindrical ionization chambers, however, the agreement was only possible when positioning the effective point of measurement of the chamber at the reference measurement depth-i.e. not complying with IAEA TRS-398 recommendations. In conclusion, for cylindrical ionization chambers, IAEA TRS-398 reference conditions for monoenergetic proton beams led to a systematic error in the determination of the absorbed dose to water, especially relevant for low-energy proton beams. To overcome this problem, the effective point of measurement of cylindrical ionization chambers should be taken into account when positioning the reference point of the chamber. Within the current IAEA TRS-398 recommendations, it seems advisable to use plane-parallel ionization chambers-rather than cylindrical chambers-for the reference dosimetry of pseudo-monoenergetic proton beams. PMID:25109620

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

2014-09-01

294

Proton beam monitor chamber calibration  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

295

Generation of proton aurora by magnetosonic waves.  

PubMed

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

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

2014-01-01

296

Generation of proton aurora by magnetosonic waves  

PubMed Central

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

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

2014-01-01

297

Generation of proton aurora by magnetosonic waves  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

298

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

299

Heteronuclear proton assisted recoupling.  

PubMed

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

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

2011-03-01

300

Far Ultraviolet Imaging from the Image Spacecraft  

NASA Technical Reports Server (NTRS)

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora. The IMAGE satellite instrument complement includes three Far Ultraviolet (FUV) instruments. The Wideband Imaging Camera (WIC) will provide broad band ultraviolet images of the aurora for maximum spatial and temporal resolution by imaging the LBH N2 bands of the aurora. The Spectrographic Imager (SI), a novel form of monochromatic imager, will image the aurora, filtered by wavelength. The proton-induced component of the aurora will be imaged separately by measuring the Doppler-shifted Lyman-a. Finally, the GEO instrument will observe the distribution of the geocoronal emission to obtain the neutral background density source for charge exchange in the magnetosphere. The FUV instrument complement looks radially outward from the rotating IMAGE satellite and, therefore, it spends only a short time observing the aurora and the Earth during each spin. To maximize photon collection efficiency and use efficiently the short time available for exposures the FUV auroral imagers WIC and SI both have wide fields of view and take data continuously as the auroral region proceeds through the field of view. To minimize data volume, the set of multiple images are electronically co-added by suitably shifting each image to compensate for the spacecraft rotation. In order to minimize resolution loss, the images have to be distort ion-corrected in real time. The distortion correction is accomplished using high speed look up tables that are pre-generated by least square fitting to polynomial functions by the on-orbit processor. The instruments were calibrated individually while on stationary platforms, mostly in vacuum chambers. Extensive ground-based testing was performed with visible and near UV simulators mounted on a rotating platform to emulate their performance on a rotating spacecraft.

Mende, S. B.; Heetderks, H.; Frey, H. U.; Lampton, M.; Geller, S. P.; Stock, J. M.; Abiad, R.; Siegmund, O. H. W.; Tremsin, A. S.; Habraken, S.

2000-01-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

302

Clinical cell therapy imaging using a perfluorocarbon tracer and fluorine-19 MRI  

PubMed Central

Purpose Cellular therapeutics are emerging as a treatment option for a host of serious human diseases. To accelerate clinical translation, noninvasive imaging of cell grafts in clinical trials can potentially be used to assess the initial delivery and behavior of cells. Methods The use of a perfluorocarbon (PFC) tracer agent for clinical fluorine-19 (19F) MRI cell detection is described. This technology was used to detect immunotherapeutic dendritic cells (DCs) delivered to colorectal adenocarcinoma patients. Autologous DC vaccines were labeled with a PFC MRI agent ex vivo. Patients received DCs intradermally, and 19F spin-density-weighted MRI at 3 Tesla (T) was used to observe cells. Results Spin-density-weighted 19F images at the injection site displayed DCs as background-free “hot-spot” images. 19F images were acquired in clinically relevant scan times (<10 min). Apparent DC numbers could be quantified in two patients from the 19F hot-spots and were observed to decrease by ?50% at injection site by 24 h. From 3T phantom studies, the sensitivity limit for DC detection is estimated to be on the order of ?105 cells/voxel in this study. Conclusion These results help to establish a clinically applicable means to track a broad range of cell types used in cell therapy. Magn Reson Med 72:1696–1701, 2014. © 2014 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance. PMID:25241945

Ahrens, Eric T; Helfer, Brooke M; O'Hanlon, Charles F; Schirda, Claudiu

2014-01-01

303

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

PubMed

In order to investigate the intense laser propagation and channel formation in dense plasma, we conducted an experiment with proton deflectometry on the OMEGA EP Laser facility. The proton image was analyzed by tracing the trajectory of mono-energetic protons, which provides understanding the electric and magnetic fields that were generated around the channel. The estimated field strengths (E ? 10(11) V/m and B ? 10(8) G) agree with the predictions from 2D-Particle-in-cell (PIC) simulations, indicating the feasibility of the proton deflectometry technique for over-critical density plasma. PMID:25430358

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

2014-11-01

304

Locating protonated amines in clathrates.  

PubMed

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

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

2013-10-01

305

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

306

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

307

Transient Electrostatic Fields and Related Energetic Proton Generation with a Plasma Fiber  

SciTech Connect

We observe a hollow structure and a fine ring in the proton images from a petawatt scale laser interaction with a 'cone-fiber' target. The protons related to the hollow structure are accelerated from the cone-tip surface and deflected later by a radial electric field surrounding the fiber. Those associated with the fine ring are accelerated from the fiber surface by this radial electric field. This field is found to decay exponentially within 3 ps from about 5x10{sup 12} V/m. Two-dimensional particle-in-cell simulations produce similar proton angular distributions.

Chen, Z.L.; Kumar, G.R.; Matsuoka, T.; Tampo, M. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Sheng, Z.M. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Sentoku, Y. [Department of Physics, University of Nevada, 5625 Fox Avenue, Reno, Nevada 89506 (United States); Tanaka, K.A.; Kodama, R. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Tsutsumi, T.; Yabuuchi, T. [Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2006-03-03

308

Proton-proton Scattering Above 3 GeV/c  

SciTech Connect

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

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

2010-01-01

309

Exclusive meson pair production in proton-proton collisions  

NASA Astrophysics Data System (ADS)

We present a study of the exclusive production of meson pairs in the four-body pp ? pp?+?-, ppK+K- reactions at high energies which constitute an irreducible background to resonance states (e.g. ?, f2(1270), f0(1500), f'2(1525), ?c0). We consider central diffractive contribution mediated by Pomeron and Reggeon exchanges and new diffractive mechanism of emission of pions/kaons from the proton lines. We include absorption effects due to proton-proton interaction and pion/kaon rescattering. Predictions for the total cross section and differential distributions in pion/kaon rapidity and transverse momentum as well as two-pion/kaon invariant mass are presented for the RHIC, Tevatron and LHC colliders. Finally we consider a measurement of exclusive production of a scalar ?c0 meson via ?c0 ? ?+?-, K+K- decay.

Lebiedowicz, Piotr; Szczurek, Antoni

2012-12-01

310

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

311

Proton irradiation effect on SCDs  

E-print Network

The Low Energy X-ray Telescope is a main payload on the Hard X-ray Modulation Telescope satellite. The swept charge device is selected for the Low Energy X-ray Telescope. As swept charge devices are sensitive to proton irradiation, irradiation test was carried out on the HI-13 accelerator at the China Institute of Atomic Energy. The beam energy was measured to be 10 MeV at the SCD. The proton fluence delivered to the SCD was $3\\times10^{8}\\mathrm{protons}/\\mathrm{cm}^{2}$ over two hours. It is concluded that the proton irradiation affects both the dark current and the charge transfer inefficiency of the SCD through comparing the performance both before and after the irradiation. The energy resolution of the proton-irradiated SCD is 212 eV@5.9 keV at $-60\\,^{\\circ}\\mathrm{C}$, while it before irradiated is 134 eV. Moreover, better performance can be reached by lowering the operating temperature of the SCD on orbit.

Yan-Ji Yang; Jing-Bin Lu; Yu-Sa Wang; Yong Chen; Yu-Peng Xu; Wei-Wei Cui; Wei Li; Zheng-Wei Li; Mao-Shun Li; Xiao-Yan Liu; Juan Wang; Da-Wei Han; Tian-Xiang Chen; Cheng-Kui Li; Jia Huo; Wei Hu; Yi Zhang; Bo Lu; Yue Zhu; Ke-Yan Ma; Di Wu; Yan Liu; Zi-Liang Zhang; Guo-He Yin; Yu Wang

2014-04-19

312

Analysis of proton transport experiments  

SciTech Connect

Intense 1-MeV proton beams, produced with the GAMBLE II generator at the Naval Research Laboratory, have been transported efficiently over a distance of one meter in a wall-stabilized, current carrying plasma channel. Ion beams from a pinch-reflex-diode were ballistically focused in a neutral-gas background so that a current-neutralized beam was injected into the plasma channel. Channels with diameters of 1.6 cm and 4.5 cm have been studied for gas pressures ranging from 0.1 to 1.5 Torr. Proton currents in the channels were diagnosed with absolutely calibrated prompt-gamma detectors using the /sup 19/F(p,..cap alpha gamma..)/sup 16/O reaction. Temporal measurements are compared with calculated prompt-gamma responses to provide proton energy losses, proton currents and transport efficiencies. For the small diameter channel, poor transport was observed. For the large diameter channel, efficient transport (33% to 100%) was deduced for peak proton currents of approx. 0.3 MA and for energy losses of a few hundred keV.

Young, F.C.; Sandel, F.L.; Stephanakis, S.J.; Blauner, P.G.; Cooperstein, G.; Goldstein, S.A.; Mosher, D.

1980-09-05

313

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

314

Proton-proton fusion in lattice effective field theory  

E-print Network

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

Gautam Rupak; Pranaam Ravi

2014-11-10

315

Proton-proton fusion in lattice effective field theory  

E-print Network

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

Rupak, Gautam

2014-01-01

316

COMPARISON OF PARTICLE-TRACKING FEATURES IN GEANT4 AND MCNPX CODES FOR APPLICATIONS IN MAPPING OF PROTON RANGE UNCERTAINTY  

PubMed Central

The accuracy of proton therapy is partially limited by uncertainties that result from changing pathological conditions in the patient such as tumor motion and shrinkage. These uncertainties can be minimized with the help of a time-resolved range telescope. Monte Carlo methods can help improve the performance of range telescopes by tracking proton interactions on a particle-by-particle basis thus broadening our understanding on the behavior of protons within the patient and the detector. This paper compared the proton multiple coulomb scattering algorithms in the Monte Carlo codes MCNPX and Geant4 to well-established scattering theories. We focus only on beam energies associated with proton imaging. Despite slight discrepancies between scattering algorithms, both codes appear to be capable of providing useful particle-tracking information for applications such as the proton range telescope. PMID:22389531

BEDNARZ, BRYAN; CHEN, GTY; PAGANETTI, HARALD; HAN, BIN; DING, AIPING; XU, X. GEORGE

2012-01-01

317

Proton Mass Shift in Muonic Hydrogen Atom  

E-print Network

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

Aiichi Iwazaki

2014-08-11

318

Polarized Proton Beams in Rhic  

NASA Astrophysics Data System (ADS)

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

Zelenski, A.

2011-01-01

319

Polarized proton beams in RHIC  

SciTech Connect

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

Zelenski, A.

2010-10-04

320

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

PubMed Central

Purpose: Monte Carlo methods are used to simulate and optimize a time-resolved proton range telescope (TRRT) in localization of intrafractional and interfractional motions of lung tumor and in quantification of proton range variations. Methods: The Monte Carlo N-Particle eXtended (MCNPX) code with a particle tracking feature was employed to evaluate the TRRT performance, especially in visualizing and quantifying proton range variations during respiration. Protons of 230 MeV were tracked one by one as they pass through position detectors, patient 4DCT phantom, and finally scintillator detectors that measured residual ranges. The energy response of the scintillator telescope was investigated. Mass density and elemental composition of tissues were defined for 4DCT data. Results: Proton water equivalent length (WEL) was deduced by a reconstruction algorithm that incorporates linear proton track and lateral spatial discrimination to improve the image quality. 4DCT data for three patients were used to visualize and measure tumor motion and WEL variations. The tumor trajectories extracted from the WEL map were found to be within ?1 mm agreement with direct 4DCT measurement. Quantitative WEL variation studies showed that the proton radiograph is a good representation of WEL changes from entrance to distal of the target. Conclusions:MCNPX simulation results showed that TRRT can accurately track the motion of the tumor and detect the WEL variations. Image quality was optimized by choosing proton energy, testing parameters of image reconstruction algorithm, and comparing to ground truth 4DCT. The future study will demonstrate the feasibility of using the time resolved proton radiography as an imaging tool for proton treatments of lung tumors. PMID:21626923

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

2011-01-01

321

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

322

Proton aurora and substorm intensifications  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

323

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 substorms intensifications is formed within a region of intense proton precipitation that is well equatorward (about 4-6 deg) of the nightside open-closed field line boundary. The precipitating protons are from a population that is energized via Earthward convection from the magnetotail into the dipolar region of the magnetosphere and may play an important role in the formation of the electron arcs leading to substorm intensifications on dipolelike field lines. 12 refs.

Samson, J.C.; Lyons, L.R.; Newell, P.T.; Creutzberg, F.; Xu, B. (Alberta Univ., Edmonton (Canada) Aerospace Corp., Space and Environmental Technology Center, Los Angeles, CA (United States) Johns Hopkins Univ., Laurel, MD (United States) National Research Council of Canada, Herzberg Inst. of Astrophysics, Ottawa (Canada) Canadian Network for Space Research, Edmonton (Canada))

1992-11-01

324

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

325

Proton aurora and substorm intensifications  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

326

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

327

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

328

Imaging of brain metastases  

PubMed Central

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

Fink, Kathleen R.; Fink, James R.

2013-01-01

329

Vision 20/20: Proton therapy  

SciTech Connect

The first patients were treated with proton beams in 1955 at the Lawrence Berkeley Laboratory in California. In 1970, proton beams began to be used in research facilities to treat cancer patients using fractionated treatment regimens. It was not until 1990 that proton treatments were carried out in hospital-based facilities using technology and techniques that were comparable to those for modern photon therapy. Clinical data strongly support the conclusion that proton therapy is superior to conventional radiation therapy in a number of disease sites. Treatment planning studies have shown that proton dose distributions are superior to those for photons in a wide range of disease sites indicating that additional clinical gains can be achieved if these treatment plans can be reliably delivered to patients. Optimum proton dose distributions can be achieved with intensity modulated protons (IMPT), but very few patients have received this advanced form of treatment. It is anticipated widespread implementation of IMPT would provide additional improvements in clinical outcomes. Advances in the last decade have led to an increased interest in proton therapy. Currently, proton therapy is undergoing transitions that will move it into the mainstream of cancer treatment. For example, proton therapy is now reimbursed, there has been rapid development in proton therapy technology, and many new options are available for equipment, facility configuration, and financing. During the next decade, new developments will increase the efficiency and accuracy of proton therapy and enhance our ability to verify treatment planning calculations and perform quality assurance for proton therapy delivery. With the implementation of new multi-institution clinical studies and the routine availability of IMPT, it may be possible, within the next decade, to quantify the clinical gains obtained from optimized proton therapy. During this same period several new proton therapy facilities will be built and the cost of proton therapy is expected to decrease, making proton therapy routinely available to a larger population of cancer patients.

Smith, Alfred R. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

2009-02-15

330

Fast nosologic imaging of the brain M. De Vos a,*, T. Laudadio a  

E-print Network

, to choose the most appropriate therapy and to perform therapy follow- up. With single voxel proton MRS­7]. Although single voxel proton MRS is a relatively fast method to characterise the metabolic signature. This information can be obtained with multivoxel proton MRSI, in combination with high-quality anatomical MR images

331

Fast neutron production from lithium converters and laser driven protons  

SciTech Connect

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

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

2013-05-15

332

Recent advances in chirally pure proton pump inhibitors.  

PubMed

Chirality is a ubiquitous natural phenomenon resulting because of a differential spatial orientation of molecules around its chiral centre. This leads to the existence of two or more spatially dissimilar forms, known as stereoisomers or enantiomers, which are non-superimposable images of each other and may significantly differ from each other with respect to pharmacokinetic and pharmacodynamic properties and molecular interaction. Thus one isomer may offer significant pharmacokinetic and therapeutic advantages as compared to the other isomer or the racemic mixture (mixture containing both enantiomers). Proton pump inhibitors are a class of drugs which have been very effective in the management of acid-related disorders. The proton pumps currently available in the market including omeprazole, pantoprazole, rabeprazole and lansoprazole are racemic mixtures of the S and R isomers. Chirally pure forms of proton pump inhibitors show a superior metabolic and pharmacokinetic profile as compared to their racemates. The therapeutic efficacy is also superior to the parent racemate. This has been clearly demonstrated with the development of esomeprazole- the S-isomer of omeprazole. S-pantoprazole and dexrabeprazole also offer therapeutic advantages as compared to racemic pantoprazole and racemic rabeprazole respectively. This article reviews the chiral developments in the proton pump inhibitors and their clinical applications. PMID:18236913

Pai, Vikas; Pai, Nitin

2007-08-01

333

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.; Belancourt, P.; Snyder, J.; Chowdhury, E.; Bang, W.; Gaul, E.; Dyer, G.; Ditmire, T.; Freeman, R. R.; Akli, K.

2013-05-01

334

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

SciTech Connect

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

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

2011-10-01

335

Long-range azimuthal correlations in proton-proton and proton-nucleus collisions from the incoherent scattering of partons  

NASA Astrophysics Data System (ADS)

We show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton-parton cross-section of ? = 1.5- 3 mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton-proton and proton-nucleus collisions at the Large Hadron Collider.

Ma, Guo-Liang; Bzdak, Adam

2014-12-01

336

Long-range azimuthal correlations in proton-proton and proton-nucleus collisions from the incoherent scattering of partons  

E-print Network

We show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton-parton cross-section of $\\sigma=1.5 - 3$ mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton-proton and proton-nucleus collisions at the Large Hadron Collider.

Guo-Liang Ma; Adam Bzdak

2014-11-13

337

Model for Solar Proton Risk Assessment  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

338

Determining the mechanism of cusp proton aurora  

PubMed Central

Earth's cusp proton aurora occurs near the prenoon and is primarily produced by the precipitation of solar energetic (2–10?keV) protons. Cusp auroral precipitation provides a direct source of energy for the high-latitude dayside upper atmosphere, contributing to chemical composition change and global climate variability. Previous studies have indicated that magnetic reconnection allows solar energetic protons to cross the magnetopause and enter the cusp region, producing cusp auroral precipitation. However, energetic protons are easily trapped in the cusp region due to a minimum magnetic field existing there. Hence, the mechanism of cusp proton aurora has remained a significant challenge for tens of years. Based on the satellite data and calculations of diffusion equation, we demonstrate that EMIC waves can yield the trapped proton scattering that causes cusp proton aurora. This moves forward a step toward identifying the generation mechanism of cusp proton aurora. PMID:23575366

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

2013-01-01

339

A photon-proton marriage  

E-print Network

The shapes of invariant differential cross section for charged hadron production as function of hadron's transverse momentum and rapidity in ep collisions at HERA machine are considered. The particle spectra shapes observed in pp and gamma-gamma collisions before have shown very different properties. This difference could be directly measured in the "mixed" type collisions of photon and proton at HERA experiments.

A. A. Bylinkin; A. A. Rostovtsev

2013-11-22

340

Alpha proton x ray spectrometer  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

341

Proton-transfer reaction dynamics  

Microsoft Academic Search

In this article we discuss the progress made in understanding intermolecular and intermolecular reactions of proton (or hydrogen-atom) transfer. Femtosecond real-time probing, together with spectroscopic studies, in molecular beams are presented with selected examples of reactions. Reaction rates, tunneling dynamics and the nature of the reaction coordinate are examined and related to two-state multidimensional potential energy surfaces.

Abderrazzak Douhal; Françoise Lahmani; Ahmed H. Zewail

1996-01-01

342

Proton structure and tensor gluons  

E-print Network

We consider a possibility that inside the proton and, more generally, inside the hadrons there are additional partons - tensor-gluons, which can carry a part of the proton momentum. The tensor-gluons have zero electric charge, like gluons, but have a larger spin. Inside the proton a nonzero density of the tensor-gluons can be generated by the emission of tensor-gluons by gluons. The last mechanism is typical for non-Abelian tensor gauge theories, in which there exists a gluon-tensor-tensor vertex of order g. Therefore the number of gluons changes not only because a quark may radiate a gluon or because a gluon may split into a quark-antiquark pair or into two gluons, but also because a gluon can split into two tensor-gluons. The process of gluon splitting suggests that part of the proton momentum which was carried by neutral partons is shared between vector and tensor gluons. We derive evolution equations for the parton distribution functions which take into account these new processes. The momentum sum rule allows to find the tensor-gluons contribution to the Callan-Simanzik beta function and to calculate the corresponding anomalous dimensions. This contribution changes the behavior of the structure functions, and the logarithmic correction to the Bjorken scaling becomes more mild. This also influences the unification scale at which the coupling constants of the Standard Model merge, shifting its value to lower energies of order of 40 TeV.

George Savvidy

2014-07-31

343

LATEST DEVELOPMENTS IN PROTON THERAPY  

Microsoft Academic Search

The intent of this review is to give insight in the present status and on the prospective future of proton therapy. The major point of reference is conventional therapy with photons. Traditional radiotherapy is showing nowadays a very rapid progress using advanced dynamic beam delivery techniques and sophisticated computer algorithms for treatment planning. The new fashionable concepts in medical physics

E. Pedroni

2000-01-01

344

Proton circulation in Vibrio costicola.  

PubMed Central

The importance of proton movements was assessed in the moderate halophile Vibrio costicola. When anaerobic cells in acidic buffer (pH 6.5) were given an O2 pulse, protons were extruded regardless of the presence of Na+. At pH 8.5, however, V. costicola produced an acidic response to an O2 pulse in the absence of Na+ and an alkaline response when Na+ was present. An Na+/H+ antiport activity was confirmed at pH 8.5. All of these effects were prevented by protonophores or butanol treatment. Growth in complex medium at pH 8.5 was prevented by a high concentration (50 microM) of carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) or a low concentration (5 microM) of another protonophore, 3,3',4',5-tetrachlorosalicylanilide (TCS). The relative ineffectiveness of the former protonophore was caused by the proteose peptone and tryptone ingredients of the complex medium, since 5 microM completely prevented growth in their absence. The results are explained by a primary respiratory-linked proton efflux coupled to a secondary Na+/H+ antiport operating at alkaline pH. Evidence was seen for a role of Na+ in stimulating proton influx at alkaline pH, presumably via the pH homeostasis mechanism. PMID:2981820

Hamaide, F; Kushner, D J; Sprott, G D

1985-01-01

345

The size of the proton  

NASA Astrophysics Data System (ADS)

The root-mean-square (rms) charge radius r p of the proton has so far been known only with a surprisingly low precision of about 1% from both electron scattering and precision spectroscopy of hydrogen. We have recently determined r p by means of laser spectroscopy of the Lamb shift in the exotic "muonic hydrogen" atom. Here, the muon, which is the 200 times heavier cousin of the electron, orbits the proton with a 200 times smaller Bohr radius. This enhances the sensitivity to the proton's finite size tremendously. Our new value r p = 0.84184 (67) fm is ten times more precise than the generally accepted CODATA-value, but it differs by 5 standard deviations from it. A lively discussion about possible solutions to the "proton size puzzle" has started. Our measurement, together with precise measurements of the 1S-2S transition in regular hydrogen and deuterium, also yields improved values of the Rydberg constant, R ? = 10,973,731.568160 (16) m - 1.

Nebel, T.; Antognini, A.; Amaro, F. D.; Biraben, F.; Cardoso, J. M. R.; Covita, D. S.; Dax, A.; Dhawan, S.; Fernandes, L. M. P.; Giesen, A.; Graf, T.; Hänsch, T. W.; Indelicato, P.; Julien, L.; Kao, C.-Y.; Knowles, P.; Kottmann, F.; Le Bigot, E.; Liu, Y.-W.; Lopes, J. A. M.; Ludhova, L.; Monteiro, C. M. B.; Mulhauser, F.; Nez, F.; Rabinowitz, P.; dos Santos, J. M. F.; Schaller, L. A.; Schuhmann, K.; Schwob, C.; Taqqu, D.; Veloso, J. F. C. A.; Pohl, R.

346

Regulation of immune responses by proton channels.  

PubMed

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

Capasso, Melania

2014-10-01

347

Proton Emission Times in Spectator Fragmentation  

E-print Network

Proton-proton correlations from spectator decays following Au + Au collisions at 1000 AMeV have been measured with an highly efficient detector hodoscope. The constructed correlation functions indicate a moderate expansion and low breakup densities similar to assumptions made in statistical multifragmentation models. In agreement with a volume breakup rather short time scales were deduced employing directional cuts in proton-proton correlations.

C. Schwarz; for the ALADIN collaboration

2000-09-05

348

Low-Energy Proton Testing Methodology  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

349

Sensitivity and Source of Amine Proton EXchange (APEX) and Amide Proton Transfer (APT) MRI in Cerebral Ischemia  

PubMed Central

Purpose Amide proton transfer (APT) and amine-water proton exchange (APEX) 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), ADC, T2 and T1 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 one hour post-occlusion, APEXw and APTw maps showed hyperintensity (3.1% of M0) and hypointensity (?1.8%), respectively, in regions with decreased ADC. Ischemia increased lactate and gamma aminobutyric acid (GABA) concentrations, but decreased glutamate and taurine concentrations. Over time, the APEXw contrast decreased with glutamate, taurine and creatine, while 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, while at decreased pH, GABA 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 amine-water proton exchange processes. Conclusion Positive APEXw contrast is more sensitive to ischemia than negative APTw contrast. They may provide complementary tissue metabolic information. PMID:23401310

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

2013-01-01

350

Do we see change of phase in proton-proton collisions at the Large Hadron Collider?  

E-print Network

High multiplicity events in proton-proton collisions at the Large Hadron Collider exhibit features resembling those found in relativistic nuclear collisions, indicating formation of medium of similar nature. Analyzing the proton-proton collision data, we find a clear signal of occurrence of change in phase between thermalized partonic matter and hadronic one as has been predicted by the lattice quantum chromodynamics.

Premomoy Ghosh; Sanjib Muhuri

2014-06-23

351

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

352

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

353

Protonation reactions and their coupling in bacteriorhodopsin  

Microsoft Academic Search

Light-induced changes of the proton affinities of amino acid side groups are the driving force for proton translocation in bacteriorhodopsin. Recent progress in obtaining structures of bacteriorhodopsin and its intermediates with an increasingly higher resolution, together with functional studies utilizing mutant pigments and spectroscopic methods, have provided important information on the molecular architecture of the proton transfer pathways and the

Sergei P. Balashov

2000-01-01

354

High-energy proton radiation belt  

Microsoft Academic Search

The experiments and theories to explain the high-energy protons trapped ; in the Earth's radiation belt are reviewed. The theory of cosmic-ray albedo ; neutron decay injection of protons into the radiation belt is discussed. Radial ; diffusion and change in the Earth's dipole moment are included along with losses ; of protons by ionization and nuclear collision. It is

R. Stephen White

1973-01-01

355

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

356

Depth dose perturbation by a hydrogel fiducial marker in a proton beam.  

PubMed

The purpose of this study was to evaluate proton depth dose perturbation caused by a radio-opaque hydrogel fiducial marker. Electronic proton stopping powers in the hydrogel were calculated for energies 0.5-250 MeV, and Monte Carlo simulations were generated of hydrogel vs. gold markers placed at various water phantom depths in a generic proton beam. Across the studied energy range, the gel/water stopping power ratio was 1.0146 to 1.0160. In the Monte Carlo simulation, the hydrogel marker caused no discernible perturbation of the proton percent depth-dose (PDD) curve. In contrast, the gold marker caused dose reductions of as much as 20% and dose shadowing regions as long as 6.5 cm. In contrast to gold markers, the radio-opaque hydrogel marker causes negligible proton depth dose perturbation. This factor may be taken into consideration for image-guided proton therapy at facilities with suitable imaging modalities. PMID:25679167

Zhang, Miao; Reyhan, Meral; Kim, Leonard H

2015-01-01

357

Spin asymmetries in lepton-proton and proton-proton diffractive reactions  

E-print Network

It is shown that the longitudinal double spin asymmetry $A_{ll}$ in polarized diffractive $Q \\bar Q$ production depends strongly on the spin structure of the quark-pomeron vertex. Relevant experiments will be possible at HERA with a polarized proton beam.

S. V. Goloskokov

1995-09-06

358

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

359

Proton-proton elastic scattering excitation functions at intermediate energies  

SciTech Connect

Polarized and unpolarized proton-proton elastic scattering is investigated with the EDDA-experiment at the Cooler Synchrotron COSY at Juelich 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 CH{sub 2} 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. [Institut fuer Strahlen- und Keruphysik. Universitaet Bonn, D-53115 Bonn (Germany)

1998-05-29

360

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

361

Proton conduction in biopolymer exopolysaccharide succinoglycan  

SciTech Connect

Protonic currents play a vital role in electrical signalling in living systems. It has been suggested that succinoglycan plays a specific role in alfalfa root nodule development, presumably acting as the signaling molecules. In this regard, charge transport and proton dynamics in the biopolymer exopolysaccharide succinoglycan have been studied by means of electrical measurements and nuclear magnetic resonance (NMR) spectroscopy. In particular, a dielectric dispersion in the system has revealed that the electrical conduction is protonic rather electronic. Besides, our laboratory- and rotating-frame {sup 1}H NMR measurements have elucidated the nature of the protonic conduction, activation of the protonic motion being associated with a glass transition.

Kweon, Jin Jung [Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of); National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Lee, Kyu Won; Kim, Hyojung; Lee, Cheol Eui, E-mail: rscel@korea.ac.kr [Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of); Jung, Seunho [Department of Bioscience and Biotechnology and UBITA, Konkuk University, Seoul 143-701 (Korea, Republic of); Kwon, Chanho [Naraebio Research Laboratories, 177 Dangha-ri, Bongdam-eup, Hawseong-si 445-892 (Korea, Republic of)

2014-07-07

362

Proton radiation damage in optical filter glass  

NASA Technical Reports Server (NTRS)

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

Grillot, Patrick N.; Rosenberg, William J.

1989-01-01

363

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

364

Proton-Proton Weak Capture in Chiral Effective Field Theory  

SciTech Connect

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 (LEC's) 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 $\\beta$ 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 $S(0)=(4.030 \\pm 0.006)\\times 10^{-23}$ MeV fm$^2$, with a $P$-wave contribution of $0.020\\times 10^{-23}$ MeV fm$^2$. The theoretical uncertainty is due to the fitting procedure of the LEC's and to the cutoff dependence. It is shown that polynomial fits to parametrize the energy dependence of the $S$-factor are inherently unstable.

Marcucci, Laura Elisa [Pisa U., INFN-Pisa; Schiavilla, Rocco [Old Dominion U., JLAB; Viviani, MIchele [INFN-Pisa

2013-05-01

365

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

366

Neutron Imaging Camera  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

367

Magnetic Resonance Detection of Individual Proton Spins Using Quantum Reporters  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

368

Very energetic protons in Saturn's radiation belt  

NASA Technical Reports Server (NTRS)

Very energetic protons are trapped in the inner Saturnian radiation belt. The University of California at San Diego instrument on Pioneer 11 has definitely identified protons of energy greater than 80 MeV on channel M3 and has tentatively detected protons of energy greater than 600 MeV on channel C3. The spatial distribution of the protons is distinct from that of the trapped electrons, the main difference being that the protons are strongly absorbed by the innermost moons and that the electrons are not. The source strength for injecting protons by the decay of cosmic ray albedo neutrons generated in the rings of Saturn has been estimated. The required proton lifetime is approximately 20 years.

Fillius, W.; Mcilwain, C.

1980-01-01

369

Proton emission from triaxial nuclei  

SciTech Connect

Proton decay from triaxially deformed nuclei is investigated. The deformation parameters corresponding to the mother nucleus are determined microscopically and the calculated decay widths are used to probe the mean-field wave function. The proton wave function in the mother nucleus is described as a resonant state in a coupled-channel formalism. The decay width, as well as the angular distribution of the decaying particle, are evaluated and their dependence upon the triaxial deformation parameters is studied in the decay of {sup 161}Re and {sup 185}Bi. It is found that the decay width is very sensitive to the parameters defining the triaxial deformation while the angular distribution is a universal function which does not depend upon details of the nuclear structure.

Delion, D.S.; Wyss, R.; Karlgren, D.; Liotta, R.J. [National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest-Magurele (Romania); KTH, Alba Nova University Center, SE-10691 Stockholm (Sweden)

2004-12-01

370

Proton radius from Bayesian inference  

NASA Astrophysics Data System (ADS)

The methods of Bayesian statistics are used to extract the value of the proton radius from the elastic e p scattering data in a model-independent way. To achieve that goal a large number of parametrizations (equivalent to neural network schemes) are considered and ranked by their conditional probability P (parametrization |data ) instead of using the minimal error criterion. As a result the most probable proton radii values (rEp=0.899 ±0.003 fm, rMp=0.879 ±0.007 fm) are obtained and systematic error due to freedom in the choice of parametrization is estimated. Correcting the data for the two-photon-exchange effect leads to smaller differences between the extracted values of rEp and rMp. The results disagree with recent muonic atom measurements.

Graczyk, Krzysztof M.; Juszczak, Cezary

2014-11-01

371

Proton synchrotrons for cancer therapy  

NASA Astrophysics Data System (ADS)

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 exclusive choice among particle accelerators. In this paper, four synchrotrons designed for dedicated therapy facilities are reviewed and performance data are discussed.

Coutrakon, George B.

2001-07-01

372

Protons in near earth orbit  

Microsoft Academic Search

The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at equatorial latitudes with a flux

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

2000-01-01

373

Proton synchrotron radiation at Fermilab  

SciTech Connect

While protons are not generally associated with synchrotron radiation, they do emit visible light at high enough energies. This paper presents an overview of the use of synchrotron radiation in the Tevatron to measure transverse emittances and to monitor the amount of beam in the abort gap. The latter is necessary to ensure a clean abort and prevent quenches of the superconducting magnets and damage to the silicon detectors of the collider experiments.

Thurman-Keup, Randy; /Fermilab

2006-05-01

374

Proton Resonance Spectroscopy -- Final Report  

SciTech Connect

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

Shriner, Jr, J F

2009-07-27

375

Solid-state proton conductors  

SciTech Connect

The purpose of this program was to survey the field of solid-state proton conductors (SSPC), identify conductors that could be used to develop solid-state fuel cells suitable for use with coal derived fuel gases, and begin the experimental research required for the development of these fuel cells. This document covers the following topics: the history of developments and current status of the SSPC, including a review of proton conducting electrolyte structures, the current status of the medium temperature SSPC development, electrodes for moderate temperature (SSPC) fuel cell, basic material and measurement techniques applicable for SSPC development, modeling and optimization studies. Correlation and optimization studies, to include correlation studies on proton conduction and oxide cathode optimization for the SSPC fuel cell. Experiments with the SSPC fuel cells including the fabrication of the electrolyte disks, apparatus for conducting measurements, the strontium-cerium based electrolyte, the barium-cerium based electrolyte with solid foil electrodes, the barium-cerium based electrolyte with porous electrodes, and conduction mechanisms. 164 refs., 27 figs., 13 tabs.

Jewulski, J.R.; Osif, T.L.; Remick, R.J.

1990-12-01

376

High-Intensity Proton Accelerator  

SciTech Connect

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

Jay L. Hirshfield

2011-12-27

377

Family symmetries and proton decay  

SciTech Connect

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 from the dimension five operator (Q{sub 1}Q{sub 1}Q{sub 2}L{sub 1,2}), where Q{sub i} and L{sub i} are i{sup th} generation quark and lepton superfields respectively. Such an operator is not generated at observable levels due to gauge or Higgs boson exchange in a minimal GUT. However in theories that explain the fermion mass hierarchy, it may be generated at the Planck scale with a strength such that the decays p {yields} K{sup 0}{ell}{sup +} are both compatible with the proton lifetime and visible at Super-Kamiokande. Observable proton decay can even occur in theories without unification.

Murayama, Hitoshi [Lawrence Berkeley Lab., CA (United States)]|[Tohoku Univ., Sendai (Japan); Kaplan, D.B. [Univ. of Washington, Seattle, WA (United States)

1994-08-01

378

Correlation-Peak Imaging  

NASA Astrophysics Data System (ADS)

Identification and quantitation in conventional 1H spectroscopic imaging in vivois often hampered by the small chemical-shift range. To improve the spectral resolution of spectroscopic imaging, homonuclear two-dimensional correlation spectroscopy has been combined with phase encoding of the spatial dimensions. From the theoretical description of the coherence-transfer signal in the Fourier-transform domain, a comprehensive acquisition and processing strategy is presented that includes optimization of the width and the position of the acquisition windows, matched filtering of the signal envelope, and graphical presentation of the cross peak of interest. The procedure has been applied to image the spatial distribution of the correlation peaks from specific spin systems in the hypocotyl of castor bean ( Ricinus communis) seedlings. Despite the overlap of many resonances, correlation-peak imaging made it possible to observe a number of proton resonances, such as those of sucrose, ?-glucose, glutamine/glutamate, lysine, and arginine.

Ziegler, A.; Metzler, A.; Köckenberger, W.; Izquierdo, M.; Komor, E.; Haase, A.; Décorps, M.; von Kienlin, M.

379

Infrared-Activated Proton Transfer in Aqueous Nafion Proton-Exchange-Membrane Nanochannels  

NASA Astrophysics Data System (ADS)

We report on the observation of a strong reorganization of the proton hydration structure in hydrated Nafion membranes following single-quantum excitation of a proton vibration with ˜4 ?m light pulses. The reorganization takes place with a time constant of 170±20 fs and leads to a strong red shift of the excited proton vibration and the rise of new waterlike O-H stretch absorption bands. These observations can be explained from a vibrational-excitation-induced change of the proton-hydration structure that involves transfer of the proton charge. The results are consistent with recent quantum molecular dynamics simulations of proton transfer in Nafion membranes.

Liu, Liyuan; Bakker, Huib J.

2014-06-01

380

Infrared-activated proton transfer in aqueous nafion proton-exchange-membrane nanochannels.  

PubMed

We report on the observation of a strong reorganization of the proton hydration structure in hydrated Nafion membranes following single-quantum excitation of a proton vibration with ?4??m light pulses. The reorganization takes place with a time constant of 170 ± 20??fs and leads to a strong red shift of the excited proton vibration and the rise of new waterlike O-H stretch absorption bands. These observations can be explained from a vibrational-excitation-induced change of the proton-hydration structure that involves transfer of the proton charge. The results are consistent with recent quantum molecular dynamics simulations of proton transfer in Nafion membranes. PMID:25014832

Liu, Liyuan; Bakker, Huib J

2014-06-27

381

Proton transport via the membrane surface.  

PubMed Central

Some proton pumps, such as cytochrome c oxidase (C(c)O), translocate protons across biological membranes at a rate that considerably exceeds the rate of proton transport to the entrance of the proton-conducting channel via bulk diffusion. This effect is usually ascribed to a proton-collecting antenna surrounding the channel entrance. In this paper, we consider a realistic phenomenological model of such an antenna. In our model, a homogeneous membrane surface, which can mediate proton diffusion toward the channel entrance, is populated with protolytic groups that are in dynamic equilibrium with the solution. Equations that describe coupled surface-bulk proton diffusion are derived and analyzed. A general expression for the rate constant of proton transport via such a coupled surface-bulk diffusion mechanism is obtained. A rigorous criterion is formulated of when proton diffusion along the surface enhances the transport. The enhancement factor is found to depend on the ratio of the surface and bulk diffusional constants, pK(a) values of surface protolytic groups, and their concentration. A capture radius for a proton on the surface and an effective size of the antenna are found. The theory also predicts the effective distance that a proton can migrate on the membrane surface between a source (such as CcO) and a sink (such as ATP synthase) without fully equilibrating with the bulk. In pure aqueous solutions, protons can travel over long distances (microns). In buffered solutions, the travel distance is much shorter (nanometers); still the enhancement effect of the surface diffusion on the proton flow to a target on the surface can be tens to hundreds at physiological buffer concentrations. These results are discussed in a general context of chemiosmotic theory. PMID:12023208

Georgievskii, Yuri; Medvedev, Emile S; Stuchebrukhov, Alexei A

2002-01-01

382

The role of proton precipitation in the excitation of auroral FUV emissions  

Microsoft Academic Search

Far ultraviolet remote sensing from a high-altitude satellite is extensively used to image the global aurora, derive its energetics, and follow its dynamical morphology. It is generally assumed that the observed emissions are dominated by the interaction of the precipitated electrons with the thermospheric constituents. A model to calculate far ultraviolet emissions excited by auroral electrons and protons and the

B. Hubert; J.-C. Gérard; D. V. Bisikalo; V. I. Shematovich; S. C. Solomon

2001-01-01

383

Developing a 3D neutron tomography method for proton exchange membrane fuel cells  

Microsoft Academic Search

Fuel cell visualization is an ongoing challenge in the world of hydrogen-based research. Neutron tomography is a powerful tool for acquiring otherwise unattainable information about the inner workings of a proton exchange membrane fuel cell. Advanced neutron imaging methods allow for validation of both cell design and run methods. The tomography techniques discussed in this paper show how 3D visualization

Hong-Yue Tang; Anthony Santamaria; Jonathan Kurniawan; Jae Wan Park; Tae-Hyun Yang; Young-Jun Sohn

2010-01-01

384

New techniques for predicting solar proton fluences for radiation effects applications  

Microsoft Academic Search

At geosynchronous altitudes, solar proton events can be a significant source of radiation exposure for devices such as optical imagers, memories and solar cells. These events appear to occur randomly with respect to time and magnitude during the active period of each solar cycle. New probabilistic descriptions, including extreme value theory, are given in forms applicable to assessing mission risks

M. A. Xapsos; G. P. Summers; P. Shapiro; E. A. Burke

1996-01-01

385

Proton MR Spectroscopy at 7 Tesla in the Macaque monkey J. Pfeuffer1  

E-print Network

Proton MR Spectroscopy at 7 Tesla in the Macaque monkey J. Pfeuffer1 , C. Juchem1 , H. Merkle2 , N/NINDS, Bethesda, MD, United States First MR spectroscopy results in the anaesthetized and the awake trained monkey-designed for MR imaging and spectroscopy of monkeys in upright position and simultaneous electrophysiological

Jegelka, Stefanie

386

Research Papers Abnormal brain chemistry in chronic back pain: an in vivo proton  

E-print Network

Research Papers Abnormal brain chemistry in chronic back pain: an in vivo proton magnetic resonance April 2000; accepted 2 May 2000 Abstract The neurobiology of chronic pain, including chronic back pain, is unknown. Structural imaging studies of the spine cannot explain all cases of chronic back pain. Functional

Apkarian, A. Vania

387

Ion-induced fluorescence imaging of endosomes  

NASA Astrophysics Data System (ADS)

Imaging laboratories at Jyväskylä and Singapore are collaborating on the development of fluorescence imaging of cytoplasmic endosomes using a combination of proton induced fluorescence (PIF) with direct Scanning Transmission Ion Microscopy (direct-STIM) for sub-cellular structural imaging. A549 lung carcinoma cells were cultivated and stained for epidermal growth factor receptor (EGFR) and receptor ?2?1 integrin. In this paper, we demonstrate that cells can be imaged at sub-150 nm resolution using the PIF technique. In addition, the same target cell was imaged at 50 and 25 nm resolution by using proton and He-STIM, respectively. The combination of both techniques offer a powerful tool to improve fluorescence imaging beyond optical diffraction limits.

Norarat, R.; Marjomäki, V.; Chen, X.; Zhaohong, M.; Minqin, R.; Chen, C.-B.; Bettiol, A. A.; Whitlow, H. J.; Watt, F.

2013-07-01

388

Proton-proton correlations observed in two-proton decay of {sup 19}Mg and {sup 16}Ne  

SciTech Connect

Proton-proton correlations were observed for the two-proton decays of the ground states of {sup 19}Mg and {sup 16}Ne. The trajectories of the respective decay products, {sup 17}Ne+p+p and {sup 14}O+p+p, were measured by using a tracking technique with microstrip detectors. These data were used to reconstruct the angular correlations of fragments projected on planes transverse to the precursor momenta. The measured three-particle correlations reflect a genuine three-body decay mechanism and allowed us to obtain spectroscopic information on the precursors with valence protons in the sd shell.

Mukha, I. [Universidad de Sevilla, E-41012 Seville (Spain); RRC Kurchatov Institute, RU-123184 Moscow (Russian Federation); Grigorenko, L. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Gesellschaft fuer Schwerionenforschung, D-64291 Darmstadt (Germany); Suemmerer, K.; Chatillon, A.; Geissel, H.; Hofmann, J.; Kurz, N.; Litvinov, Yu.; Nociforo, C.; Ott, W.; Roeckl, E.; Weick, H. [Gesellschaft fuer Schwerionenforschung, D-64291 Darmstadt (Germany); Acosta, L.; Garcia-Ramos, J. E.; Martel, I. [Universidad de Huelva, E-21071 Huelva (Spain); Alvarez, M. A. G.; Espino, J. M.; Gomez-Camacho, J. [Universidad de Sevilla, E-41012 Seville (Spain); Casarejos, E.; Cortina-Gil, D. [Universidade de Santiago de Compostela, E-15782 Santiago de Compostela (Spain)] (and others)

2008-06-15

389

High-energy proton radiation belt.  

NASA Technical Reports Server (NTRS)

The experiments and theories to explain the high-energy protons trapped in the earth's radiation belt are reviewed. The theory of cosmic ray albedo neutron decay injection of protons into the radiation belt is discussed. Radial diffusion and change in the earth's dipole moment are considered along with losses of protons by ionization and nuclear collision. It is found that the measured albedo neutron escape current is sufficient to supply trapped protons above 30 MeV. The theoretical calculations of the trapped protons are in agreement with the measurements for L less than or equal to 1.7 both on and off the equator. For L greater than or equal to 1.7, additional trapped proton differential energy measurements should be made before the theory can be adequately tested. It appears that an additional loss mechanism such as pitch angle scattering may be required.

White, R. S.

1973-01-01

390

The design and implementation of decision support tools of proton beam therapy treatment planning of brain cancer patients  

Microsoft Academic Search

Last year, we presented methodology to perform knowledge-based medical imaging informatics research on specific clinical scenarios where brain tumor patients are treated with Proton Beam Therapy (PT). In this presentation, we demonstrate the design and implementation of quantification and visualization tools to develop the knowledge base for therapy treatment planning based on DICOM-RT-ION objects. Proton Beam Therapy (PT) is a

Anh Le; Jorge Documet; Anika Joseph; Reinhard Schulte; Brent Liu

2008-01-01

391

Proton-cone-beam-computed-tomography  

Microsoft Academic Search

A prototype proton-cone-beam-computed-tomography (PCB-CT) system utilizing a proton radiatiotherapy beam has been developed. The system acquires CT data in the cone-beam geometry. The cone-beam is produced by scattering a 158.6 MeV narrow parallel proton beam on a range modifier in the form of a linear modulating wheel. The wheel is a PMMA propeller of variable thickness that rotates about its

Piotr Zygmanski

1998-01-01

392

Molecular mechanisms for generating transmembrane proton gradients  

PubMed Central

Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side. PMID:23507617

Gunner, M.R.; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

2013-01-01

393

Molecular Mechanism of Biological Proton Transport  

SciTech Connect

Proton transport across lipid membranes is a fundamental aspect of biological energy transduction (metabolism). This function is mediated by a Grotthuss mechanism involving proton hopping along hydrogen-bonded networks embedded in membrane-spanning proteins. Using molecular simulations, the authors have explored the structural, dynamic, and thermodynamic properties giving rise to long-range proton translocation in hydrogen-bonded networks involving water molecules, or water wires, which are emerging as ubiquitous H{sup +}-transport devices in biological systems.

Pomes, R.

1998-09-01

394

Superparamagnetic iron oxide nanoparticles Proton Nuclear Magnetic Resonance Dispersion curves  

NASA Astrophysics Data System (ADS)

Superparamagnetic nanoparticles are widely used as contrast agents for magnetic resonance imaging. We present the Proton Nuclear Magnetic Resonance Dispersion curves for colloidal suspension of iron oxide nanoparticles used as contrast agents. The systems studied are composed of iron oxide nanoparticles of two different sizes, 80 150nm dextran coated and 300 400nm silicon coated. Previous studies show that the longitudinal relaxation time dispersion as a function of the proton Larmor frequency is not easily obtained for the aqueous colloidal suspension of 300 400nm diameter nanoparticles. We obtained this system longitudinal relaxation time dispersion over a broad range of magnetic fields in a viscous medium. A theoretical model that accounts for the relaxation rate of water protons under the influence of such colloidal superparamagnetic nanoparticles was fitted to the experimental data of both systems. The fit allows access to characteristic parameters of superparamagnetic nanoparticles such as the Néel relaxation time, the nanoparticle radius, particle's magnetic moment and translational correlation time, important parameters for the contrast agent efficiency.

Taborda, A.; Carvalho, A.

2008-08-01

395

The Study of Solar Energetic Protons Associated with EUV Waves  

NASA Astrophysics Data System (ADS)

We studied the relationship between solar energetic protons (SEPs) and extreme ultraviolet (EUV) wave properties between 2010 August and 2013 May observed by STEREO, SOHO and SDO. We determined the onset times, peak times and peak fluxes of the SEPs in SOHO ERNE and STEREO LET proton channel (6 - 10 MeV). Full Sun heliographic images created by combining STB 195Å, SDO 193Å, and STA 195Å were used for the analysis of the EUV waves. EUV wave arrival times at the spacecraft connecting points and their speed on the low corona were determined by space-time plots. It is noted that there is a significant correlation between the EUV wave arrival times and SEP onset times (r=0.73) but no SEP peak times. SEP peak fluxes increase with EUV wave speed (r=0.69) and the power law spectral index become harder with the EUV wave speed. This suggests that energetic protons are strongly associated with EUV waves, which is considered as the signature of CME shock in the low corona.

Park, Jinhye; Innes, Davina; Bucik, Radoslav; Moon, Yong-Jae; Kahler, Stephen W.

2014-06-01

396

Mean transverse mass of hadrons in proton-proton reactions  

E-print Network

An energy dependence of the mean transverse mass $\\langle m_T\\rangle$ at mid-rapidity in proton-proton ($p+p$) reactions is studied within the ultra-relativistic quantum molecular dynamics (UrQMD). The UrQMD model predicts a nonmonotonous dependence of $\\langle m_T\\rangle$ on collision energy for several hadron species: for $\\pi^+$, $p$, $K^+$, and $\\Lambda$ the mean transverse mass has a maximum at the center of mass energy region $5\\le \\sqrt{s}\\le 8$ GeV. These results are a consequence of an interplay of two contributions: 1) excitations and decays of the baryonic resonances $N^*$ and $\\Delta$; 2) excitations and decays of the baryonic strings. The UrQMD results do not show any nonmonotonous dependence of $\\langle m_T\\rangle$ on $\\sqrt{s}$ for $\\pi^-$, $K^{-}$, and antiprotons. Whether a nonmonotonous dependence of $\\langle m_T\\rangle$ at mid-rapidity on the collision energy for $\\pi^+$, $p$, $K^+$, and $\\Lambda$ is relevant for real $p+p$ interactions will be soon checked experimentally by the NA61/SHINE Collaboration.

V. Yu. Vovchenko; D. V. Anchishkin; M. I. Gorenstein

2014-08-23

397

Mean transverse mass of hadrons in proton-proton reactions  

E-print Network

An energy dependence of the mean transverse mass $\\langle m_T\\rangle$ at mid-rapidity in proton-proton ($p+p$) reactions is studied within the ultra-relativistic quantum molecular dynamics (UrQMD). The UrQMD model predicts a nonmonotonous dependence of $\\langle m_T\\rangle$ on collision energy for several hadron species: for $\\pi^+$, $p$, $K^+$, and $\\Lambda$ the mean transverse mass has a maximum at the center of mass energy region $5\\le \\sqrt{s}\\le 8$ GeV. These results are a consequence of an interplay of two contributions: 1) excitations and decays of the baryonic resonances $N^*$ and $\\Delta$; 2) excitations and decays of the baryonic strings. The UrQMD results do not show any nonmonotonous dependence of $\\langle m_T\\rangle$ on $\\sqrt{s}$ for $\\pi^-$, $K^{-}$, and antiprotons. Whether a nonmonotonous dependence of $\\langle m_T\\rangle$ at mid-rapidity on the collision energy for $\\pi^+$, $p$, $K^+$, and $\\Lambda$ is relevant for real $p+p$ interactions will be soon checked experimentally by the NA61/SHINE ...

Vovchenko, V Yu; Gorenstein, M I

2014-01-01

398

Open charm production in high multiplicity proton-proton events at the LHC  

E-print Network

We present the dependence of $D$ production on the charged particle multiplicity in proton-proton collisions at LHC energies. We show that, in a framework of source coherence, the open charm production exhibits a growth with the multiplicity which is stronger than linear in the high density domain. This departure from linearity was previously observed in the $J/\\psi$ inclusive data from proton-proton collisions at 7 TeV and was successfully described in our approach. Our assumption, the existence of coherence effects present in proton-proton collisions at high energy, applies for high multiplicity proton-proton collisions in the central rapidity region and should affect any hard observable.

Ferreiro, E G

2015-01-01

399

1H Chemical Shift Magnetic Resonance Imaging Probes with High Sensitivity for Multiplex Imaging  

PubMed Central

Proton-based chemical shift imaging (CSI) probes were encapsulated inside nano-carriers to increase the sensivitity of the reporters. Co-encapsulation with a relaxation agent results in improved sensitivity and suppresses background signals. Simultaneous imaging of different chemical shift reporters allows multiplexed detection. PMID:22434641

Yang, Yan; Schühle, Daniel T.; Dai, Guangping; Alford, Jamu

2012-01-01

400

Proton beam therapy control system  

DOEpatents

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

Baumann, Michael A. (Riverside, CA); Beloussov, Alexandre V. (Bernardino, CA); Bakir, Julide (Alta Loma, CA); Armon, Deganit (Redlands, CA); Olsen, Howard B. (Colton, CA); Salem, Dana (Riverside, CA)

2008-07-08

401

Proton beam therapy control system  

DOEpatents

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

Baumann, Michael A. (Riverside, CA); Beloussov, Alexandre V. (San Bernardino, CA); Bakir, Julide (Alta Loma, CA); Armon, Deganit (Longmeadow, MA); Olsen, Howard B. (Irvine, CA); Salem, Dana (Riverside, CA)

2010-09-21

402

Linear energy transfer of proton clusters  

NASA Astrophysics Data System (ADS)

In conventional particle accelerators, protons are produced in long pulses, in which the average inter-proton distance is in the order of tens of centimeters or more. Therefore, the radiobiology of conventionally accelerated protons is primarily governed by the interaction of a single proton with the cell. In a laser-plasma interaction scheme, the accelerated protons come as a single bunch of particles (less than 1 ps in duration) with inter particle distances that are many orders of magnitude shorter than those in conventional particle accelerators. As laser-accelerated protons traverse the medium, they not only interact with each other, but also with the host medium. It is shown that when the average distance between protons in a cluster is less than or equal to their velocity divided by the characteristic frequency of the collective excitations supported by the medium, the cluster's linear stopping power increases and can reach several times that of sparsely distributed protons. As a result, the elevated radio biological effectiveness of the proton cluster may take place and conditions for its experimental observation are presented.

Fourkal, E.; Velchev, I.; Ma, C.-M.; Fan, J.

2011-05-01

403

Proton radioactivity half lives with Skyrme interactions  

E-print Network

The potential barrier impeding the spontaneous emission of protons in the proton radioactive nuclei is calculated as the sum of nuclear, Coulomb and centrifugal contributions. The nuclear part of the proton-nucleus interaction potential is obtained in the energy density formalism using Skyrme effective interaction that results into a simple algebraic expression. The half-lives of the proton emitters are calculated for the different Skyrme sets within the improved WKB framework. The results are found to be in reasonable agreement with the earlier results obtained for more complicated calculations involving finite range interactions.

T. R. Routray; Abhishek Mishra; S. K. Tripathy; B. Behera; D. N. Basu

2012-05-31

404

Evaluation of a metal artifact reduction algorithm in CT studies used for proton radiotherapy treatment planning.  

PubMed

Metal objects in the body such as hip prostheses cause artifacts in CT images. When CT images degraded by artifacts are used for treatment planning of radiotherapy, the artifacts can yield inaccurate dose calculations and, for particle beams, erroneous penetration depths. A metal artifact reduction software (O-MAR) installed on a Philips Brilliance Big Bore CT has been tested for applications in treatment planning of proton radiotherapy. Hip prostheses mounted in a water phantom were used as test objects. Images without metal objects were acquired and used as reference data for the analysis of artifact-affected regions outside of the metal objects in both the O-MAR corrected and the uncorrected images. Water equivalent thicknesses (WET) based on proton stopping power data were calculated to quantify differences in the calculated proton beam penetration for the different image sets. The WET to a selected point of interest between the hip prostheses was calculated for several beam directions of clinical relevance. The results show that the calculated differences in WET relative to the reference case were decreased when the O-MAR algorithm was applied. WET differences up to 2.0 cm were seen in the uncorrected case while, for the O-MAR corrected case, the maximum difference was decreased to 0.4 cm. The O-MAR algorithm can significantly improve the accuracy in proton range calculations. However, there are some residual effects, and the use of proton beam directions along artifact streaks should only be used with caution and appropriate margins. PMID:25207572

Andersson, Karin M; Ahnesjö, Anders; Vallhagen Dahlgren, Christina

2014-01-01

405

Monte Carlo and Analytical Calculation of Lateral Deflection of Proton Beams in Homogeneous Targets  

SciTech Connect

Proton radiation therapy is a precise form of radiation therapy, but the avoidance of damage to critical normal tissues and the prevention of geographical tumor misses require accurate knowledge of the dose delivered to the patient and the verification of his position demand a precise imaging technique. In proton therapy facilities, the X-ray Computed Tomography (xCT) is the preferred technique for the planning treatment of patients. This situation has been changing nowadays with the development of proton accelerators for health care and the increase in the number of treated patients. In fact, protons could be more efficient than xCT for this task. One essential difficulty in pCT image reconstruction systems came from the scattering of the protons inside the target due to the numerous small-angle deflections by nuclear Coulomb fields. The purpose of this study is the comparison of an analytical formulation for the determination of beam lateral deflection, based on Moliere's theory and Rutherford scattering with Monte Carlo calculations by SRIM 2008 and MCNPX codes.

Pazianotto, Mauricio T.; Inocente, Guilherme F.; Silva, Danilo Anacleto A. d; Hormaza, Joel M. [Departamento de Fisica e Biofisica-Instituto de Biociencias, Universidade Estadual Paulista 'Julio de Mesquita Filho'-Botucatu-SP, Brasil and Distrito de Rubiao Junior s/no 18608-000 Botucatu, SP (Brazil)

2010-05-21

406

Benchmarking of Proton Transport in Super Monte Carlo Simulation Program  

NASA Astrophysics Data System (ADS)

The Monte Carlo (MC) method has been traditionally applied in nuclear design and analysis due to its capability of dealing with complicated geometries and multi-dimensional physics problems as well as obtaining accurate results. The Super Monte Carlo Simulation Program (SuperMC) is developed by FDS Team in China for fusion, fission, and other nuclear applications. The simulations of radiation transport, isotope burn-up, material activation, radiation dose, and biology damage could be performed using SuperMC. Complicated geometries and the whole physical process of various types of particles in broad energy scale can be well handled. Bi-directional automatic conversion between general CAD models and full-formed input files of SuperMC is supported by MCAM, which is a CAD/image-based automatic modeling program for neutronics and radiation transport simulation. Mixed visualization of dynamical 3D dataset and geometry model is supported by RVIS, which is a nuclear radiation virtual simulation and assessment system. Continuous-energy cross section data from hybrid evaluated nuclear data library HENDL are utilized to support simulation. Neutronic fixed source and critical design parameters calculates for reactors of complex geometry and material distribution based on the transport of neutron and photon have been achieved in our former version of SuperMC. Recently, the proton transport has also been intergrated in SuperMC in the energy region up to 10 GeV. The physical processes considered for proton transport include electromagnetic processes and hadronic processes. The electromagnetic processes include ionization, multiple scattering, bremsstrahlung, and pair production processes. Public evaluated data from HENDL are used in some electromagnetic processes. In hadronic physics, the Bertini intra-nuclear cascade model with exitons, preequilibrium model, nucleus explosion model, fission model, and evaporation model are incorporated to treat the intermediate energy nuclear reactions for proton. Some other hadronic models are also being developed now. The benchmarking of proton transport in SuperMC has been performed according to Accelerator Driven subcritical System (ADS) benchmark data and model released by IAEA from IAEA's Cooperation Research Plan (CRP). The incident proton energy is 1.0 GeV. The neutron flux and energy deposition were calculated. The results simulated using SupeMC and FLUKA are in agreement within the statistical uncertainty inherent in the Monte Carlo method. The proton transport in SuperMC has also been applied in China Lead-Alloy cooled Reactor (CLEAR), which is designed by FDS Team for the calculation of spallation reaction in the target.

Wang, Yongfeng; Li, Gui; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Wu, Yican

2014-06-01

407

Proton aurora related to intervals of pulsations of diminishing periods  

E-print Network

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

California at Berkeley, University of

408

Incremental chemical etching of CR-39 detectors for nondispersive proton spectroscopy with high resolution  

NASA Astrophysics Data System (ADS)

Experiments on shock wave proton acceleration in a hydrogen gas plasma using multi-terawatt CO2 laser have produced ˜20MeV proton beams with a narrow energy spread [D.Haberberger et al, Proceedings of PAC2011, New York, Paper TuOBN6]. The laser-accelerated proton beam is detected by a stack of 1 mm thick CR-39 with a 100x100 mm^2 area. This nondispersive imaging spectrometer, located at 150 mm from the plasma,provided a superb spatial resolution but its spectral resolution was limited due to the 1 mm CR-39 thickness. In order to increase the spectral resolution, the incremental layer etching technique has been developed and tested using a computer control system for proton pits counting and analysis. Using this etching technique we reached spectral resolution <=60KeV per etching step and confirmed the generation of mono-energetic proton beam centered around 20MeV with an energy spread dE/E around 1%. Results on bulk etching rate and proton related track size evolution as well as limitations of this method will be presented.

Gong, Chao; Tochitsky, Sergei; Haberberger, Dan; Joshi, Chan

2011-11-01

409

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

SciTech Connect

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

Stephen Pordes et al.

2003-06-04

410

Evaluated Gas Phase Basicities and Proton Affinities of Molecules; Heats of Formation of Protonated Molecules  

Microsoft Academic Search

The available data on gas phase basicities and proton affinities of molecules are compiled and evaluated. Tables giving the molecules ordered (1) according to proton affinity and (2) according to empirical formula, sorted alphabetically are provided. The heats of formation of the molecules and the corresponding protonated species are also listed.

Sharon G. Lias; Joel F. Liebman; Rhoda D. Levin

1984-01-01

411

Charge Delocalization in Proton Channels, I: The Aquaporin Channels and Proton Blockage  

Microsoft Academic Search

The explicit contribution to the free energy barrier and proton conductance from the delocalized nature of the excess proton is examined in aquaporin channels using an accurate all-atom molecular dynamics computer simulation model. In particular, the channel permeation free energy profiles are calculated and compared for both a delocalized (fully Grotthuss shuttling) proton and a classical (nonshuttling) hydronium ion along

Hanning Chen; Boaz Ilan; Yujie Wu; Fangqiang Zhu; Klaus Schulten; Gregory A. Voth

2007-01-01

412

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

Microsoft Academic Search

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

Anton Burykin; Arieh Warshel

2003-01-01

413

Parameterization of spectral distributions for pion and kaon production in proton-proton collisions  

NASA Technical Reports Server (NTRS)

Accurate semi-empirical parameterizations of the energy-differential cross sections for charged pion and kaon production from proton-proton collisions are presented at energies relevant to cosmic rays. The parameterizations depend on the outgoing meson momentum and also the proton energy, and are able to be reduced to very simple analytical formulas suitable for cosmic-ray transport.

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

1995-01-01

414

PROTONATED POLYCYCLIC AROMATIC HYDROCARBONS REVISITED  

SciTech Connect

We reconsider the contribution that singly protonated polycyclic aromatic hydrocarbons (PAHs; HPAH{sup +}s) might make to the Class A component of the 6.2 {mu}m interstellar emission feature in light of the recent experimental measurements of protonated naphthalene and coronene. Our calculations on the small HPAH{sup +}s have a band near 6.2 {mu}m, as found in experiment. While the larger HPAH{sup +}s still have emission near 6.2 {mu}m, the much larger intensity of the band near 6.3 {mu}m overwhelms the weaker band at 6.2 {mu}m, so that the 6.2 {mu}m band is barely visible. Since the large PAHs are more representative of those in the interstellar medium, our work suggests that large HPAH{sup +}s cannot be major contributors to the observed emission at 6.2 {mu}m (i.e., Class A species). Saturating large PAH cations with hydrogen atoms retains the 6.2 {mu}m Class A band position, but the rest of the spectrum is inconsistent with observed spectra.

Ricca, Alessandra [Carl Sagan Center, SETI Institute, 189 N. Bernardo Ave., Suite 100, Mountain View, CA 94043 (United States); Bauschlicher, Charles W. Jr [Entry Systems and Technology Division, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Allamandola, Louis J., E-mail: Alessandra.Ricca-1@nasa.gov, E-mail: Charles.W.Bauschlicher@nasa.gov [Space Science Division, Mail Stop 245-6, NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2011-02-01

415

Fast protonic conducting solid electrolytes  

NASA Astrophysics Data System (ADS)

Theoretical and experimental research on glassy and crystalline solid electrolytes materials has been pursued. In lithium aluminum silicate we found that the presence of disorder in the aluminosilicate framework can exert substantial effects on the conductivity of the lithium ion; in particular the activation energy for ionic motion is substantially lower in the glassy phase than in the crystalline one, despite the greater disorder in the glass. This was explained in terms of reduced effects of interionic correlation in the disordered material compared to the rigidly alternating crystal. This substantial reduction in the localizing effects of ionic correlations should be operative in all glasses, and may account for enhancements of conductivity in stoichiometric glass compositions at relatively low temperatures. Complex impedance spectroscopy, magnetic resonance, vibrational spectroscopy and differential anomalous scattering techniques have been used to study local structures in silver selenide-germanium selenide glasses. The data seems to show the coexistence of well-defined local order with typical glassy randomness. Diffusion measurements on both uranyl phosphate and beta alumina protonic electrolytes were completed using nuclear magnetic resonance spectroscopy. The results strongly suggest that the Grotthus mechanism is not operative here. A detailed study of the transport properties of the proton conducting hydrogen-uranyl-periodate-water glasses was made.

Ratner, Mark A.; Whitmore, Donald H.

416

New interplanetary proton fluence model  

NASA Technical Reports Server (NTRS)

A new predictive engineering model for the interplanetary fluence of protons with above 10 MeV and above 30 MeV is described. The data set used is a combination of observations made from the earth's surface and from above the atmosphere between 1956 and 1963 and observations made from spacecraft in the vicinity of earth between 1963 and 1985. The data cover a time period three times as long as the period used in earlier models. With the use of this data set the distinction between 'ordinary proton events' and 'anomalously large events' made in earlier work disappears. This permitted the use of statistical analysis methods developed for 'ordinary events' on the entire data set. The greater than 10 MeV fluences at 1 AU calculated with the new model are about twice those expected on the basis of models now in use. At energies above 30 MeV, the old and new models agree. In contrast to earlier models, the results do not depend critically on the fluence from any one event and are independent of sunspot number. Mission probability curves derived from the fluence distribution are presented.

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

1990-01-01

417

Photoinduced processes in protonated tryptamine  

NASA Astrophysics Data System (ADS)

The electronic excited state dynamics of protonated tryptamine ions generated by an electrospray source have been studied by means of photoinduced dissociation technique on the femtosecond time scale. The result is that the initially excited state decays very quickly within 250fs. The photoinduced