LOR-interleaving image reconstruction for PET imaging with fractional-crystal collimation

International Nuclear Information System (INIS)

Li, Yusheng; Matej, Samuel; Karp, Joel S; Metzler, Scott D

2015-01-01

Positron emission tomography (PET) has become an important modality in medical and molecular imaging. However, in most PET applications, the resolution is still mainly limited by the physical crystal sizes or the detector’s intrinsic spatial resolution. To achieve images with better spatial resolution in a central region of interest (ROI), we have previously proposed using collimation in PET scanners. The collimator is designed to partially mask detector crystals to detect lines of response (LORs) within fractional crystals. A sequence of collimator-encoded LORs is measured with different collimation configurations. This novel collimated scanner geometry makes the reconstruction problem challenging, as both detector and collimator effects need to be modeled to reconstruct high-resolution images from collimated LORs. In this paper, we present a LOR-interleaving (LORI) algorithm, which incorporates these effects and has the advantage of reusing existing reconstruction software, to reconstruct high-resolution images for PET with fractional-crystal collimation. We also develop a 3D ray-tracing model incorporating both the collimator and crystal penetration for simulations and reconstructions of the collimated PET. By registering the collimator-encoded LORs with the collimator configurations, high-resolution LORs are restored based on the modeled transfer matrices using the non-negative least-squares method and EM algorithm. The resolution-enhanced images are then reconstructed from the high-resolution LORs using the MLEM or OSEM algorithm. For validation, we applied the LORI method to a small-animal PET scanner, A-PET, with a specially designed collimator. We demonstrate through simulated reconstructions with a hot-rod phantom and MOBY phantom that the LORI reconstructions can substantially improve spatial resolution and quantification compared to the uncollimated reconstructions. The LORI algorithm is crucial to improve overall image quality of collimated PET, which

Design and evaluation of the MAMMI dedicated breast PET

International Nuclear Information System (INIS)

Moliner, L.; González, A. J.; Soriano, A.; Sánchez, F.; Correcher, C.; Orero, A.; Carles, M.; Vidal, L. F.; Barberá, J.; Caballero, L.; Seimetz, M.; Vázquez, C.; Benlloch, J. M.

2012-01-01

Purpose: A breast dedicated positron emission tomography (PET) scanner has been developed based on monolithic LYSO crystals coupled to position sensitive photomultiplier tubes (PSPMTs). In this study, we describe the design of the PET system and report on its performance evaluation. Methods: MAMMI is a breast PET scanner based on monolithic LYSO crystals. It consists of 12 compact modules with a transaxial field of view (FOV) of 170 mm in diameter and 40 mm axial FOV that translates to cover up to 170 mm. The patient lies down in a prone position that facilitates maximum breast elongation. Quantitative performance analysis of the calculated method for the attenuation correction specifically developed for MAMMI, and based on PET image segmentation, has also been conducted in this evaluation. In order to fully determine the MAMMI prototype's performance, we have adapted the measurements suggested for National Electrical Manufacturers Association (NEMA) NU 2-2007 and NU 4-2008 protocol tests, as they are defined for whole-body and small animal PET scanners, respectively. Results: Spatial resolutions of 1.6, 1.8, and 1.9 mm were measured in the axial, radial, and tangential directions, respectively. A scatter fraction of 20.8% was obtained and the maximum NEC was determined to be 25 kcps at 44 MBq. The average sensitivity of the system was observed to be 1% for an energy window of (250 keV–750 keV) and a maximum absolute sensitivity of 1.8% was measured at the FOV center. Conclusions: The overall performance of the MAMMI reported on this evaluation quantifies its ability to produce high quality PET images. Spatial resolution values below 3 mm were measured in most of the FOV. Only the radial component of spatial resolution exceeds the 3 mm at radial positions larger than 60 mm. This study emphasizes the need for standardized testing methodologies for dedicated breast PET systems similar to NEMA standards for whole-body and small animal PET scanners.

Test beam measurement of the first prototype of the fast silicon pixel monolithic detector for the TT-PET project

Science.gov (United States)

Paolozzi, L.; Bandi, Y.; Benoit, M.; Cardarelli, R.; Débieux, S.; Forshaw, D.; Hayakawa, D.; Iacobucci, G.; Kaynak, M.; Miucci, A.; Nessi, M.; Ratib, O.; Ripiccini, E.; Rücker, H.; Valerio, P.; Weber, M.

2018-04-01

The TT-PET collaboration is developing a PET scanner for small animals with 30 ps time-of-flight resolution and sub-millimetre 3D detection granularity. The sensitive element of the scanner is a monolithic silicon pixel detector based on state-of-the-art SiGe BiCMOS technology. The first ASIC prototype for the TT-PET was produced and tested in the laboratory and with minimum ionizing particles. The electronics exhibit an equivalent noise charge below 600 e‑ RMS and a pulse rise time of less than 2 ns , in accordance with the simulations. The pixels with a capacitance of 0.8 pF were measured to have a detection efficiency greater than 99% and, although in the absence of the post-processing, a time resolution of approximately 200 ps .

Monolith electroplating process

Science.gov (United States)

Agarrwal, Rajev R.

2001-01-01

An electroplating process for preparing a monolith metal layer over a polycrystalline base metal and the plated monolith product. A monolith layer has a variable thickness of one crystal. The process is typically carried in molten salts electrolytes, such as the halide salts under an inert atmosphere at an elevated temperature, and over deposition time periods and film thickness sufficient to sinter and recrystallize completely the nucleating metal particles into one single crystal or crystals having very large grains. In the process, a close-packed film of submicron particle (20) is formed on a suitable substrate at an elevated temperature. The temperature has the significance of annealing particles as they are formed, and substrates on which the particles can populate are desirable. As the packed bed thickens, the submicron particles develop necks (21) and as they merge into each other shrinkage (22) occurs. Then as micropores also close (23) by surface tension, metal density is reached and the film consists of unstable metal grain (24) that at high enough temperature recrystallize (25) and recrystallized grains grow into an annealed single crystal over the electroplating time span. While cadmium was used in the experimental work, other soft metals may be used.

Implementation and analysis of list mode algorithm using tubes of response on a dedicated brain and breast PET

Science.gov (United States)

Moliner, L.; Correcher, C.; González, A. J.; Conde, P.; Hernández, L.; Orero, A.; Rodríguez-Álvarez, M. J.; Sánchez, F.; Soriano, A.; Vidal, L. F.; Benlloch, J. M.

2013-02-01

In this work we present an innovative algorithm for the reconstruction of PET images based on the List-Mode (LM) technique which improves their spatial resolution compared to results obtained with current MLEM algorithms. This study appears as a part of a large project with the aim of improving diagnosis in early Alzheimer disease stages by means of a newly developed hybrid PET-MR insert. At the present, Alzheimer is the most relevant neurodegenerative disease and the best way to apply an effective treatment is its early diagnosis. The PET device will consist of several monolithic LYSO crystals coupled to SiPM detectors. Monolithic crystals can reduce scanner costs with the advantage to enable implementation of very small virtual pixels in their geometry. This is especially useful for LM reconstruction algorithms, since they do not need a pre-calculated system matrix. We have developed an LM algorithm which has been initially tested with a large aperture (186 mm) breast PET system. Such an algorithm instead of using the common lines of response, incorporates a novel calculation of tubes of response. The new approach improves the volumetric spatial resolution about a factor 2 at the border of the field of view when compared with traditionally used MLEM algorithm. Moreover, it has also shown to decrease the image noise, thus increasing the image quality.

Implementation and analysis of list mode algorithm using tubes of response on a dedicated brain and breast PET

International Nuclear Information System (INIS)

Moliner, L.; Correcher, C.; González, A.J.; Conde, P.; Hernández, L.; Orero, A.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Soriano, A.; Vidal, L.F.; Benlloch, J.M.

2013-01-01

In this work we present an innovative algorithm for the reconstruction of PET images based on the List-Mode (LM) technique which improves their spatial resolution compared to results obtained with current MLEM algorithms. This study appears as a part of a large project with the aim of improving diagnosis in early Alzheimer disease stages by means of a newly developed hybrid PET-MR insert. At the present, Alzheimer is the most relevant neurodegenerative disease and the best way to apply an effective treatment is its early diagnosis. The PET device will consist of several monolithic LYSO crystals coupled to SiPM detectors. Monolithic crystals can reduce scanner costs with the advantage to enable implementation of very small virtual pixels in their geometry. This is especially useful for LM reconstruction algorithms, since they do not need a pre-calculated system matrix. We have developed an LM algorithm which has been initially tested with a large aperture (186 mm) breast PET system. Such an algorithm instead of using the common lines of response, incorporates a novel calculation of tubes of response. The new approach improves the volumetric spatial resolution about a factor 2 at the border of the field of view when compared with traditionally used MLEM algorithm. Moreover, it has also shown to decrease the image noise, thus increasing the image quality

Crystal timing offset calibration method for time of flight PET scanners

Science.gov (United States)

Ye, Jinghan; Song, Xiyun

2016-03-01

In time-of-flight (TOF) positron emission tomography (PET), precise calibration of the timing offset of each crystal of a PET scanner is essential. Conventionally this calibration requires a specially designed tool just for this purpose. In this study a method that uses a planar source to measure the crystal timing offsets (CTO) is developed. The method uses list mode acquisitions of a planar source placed at multiple orientations inside the PET scanner field-of-view (FOV). The placement of the planar source in each acquisition is automatically figured out from the measured data, so that a fixture for exactly placing the source is not required. The expected coincidence time difference for each detected list mode event can be found from the planar source placement and the detector geometry. A deviation of the measured time difference from the expected one is due to CTO of the two crystals. The least squared solution of the CTO is found iteratively using the list mode events. The effectiveness of the crystal timing calibration method is evidenced using phantom images generated by placing back each list mode event into the image space with the timing offset applied to each event. The zigzagged outlines of the phantoms in the images become smooth after the crystal timing calibration is applied. In conclusion, a crystal timing calibration method is developed. The method uses multiple list mode acquisitions of a planar source to find the least squared solution of crystal timing offsets.

Nonisothermal melt-crystallization kinetics for in situ prepared poly(ethylene terephthalate)/monmorilonite (PET/OMMT)

International Nuclear Information System (INIS)

Antoniadis, G.; Paraskevopoulos, K.M.; Vassiliou, A.A.; Papageorgiou, G.Z.; Bikiaris, D.; Chrissafis, K.

2011-01-01

Highlights: → The melting temperature of the nanocomposites was shifted slightly to higher temperatures. → OMMT can act as nucleating agent. → The samples present lower activation energy compared to that of neat PET. → They crystallized by mechanisms with different activation energies. - Abstract: Poly(ethylene terephthalate) (PET) montmorillonite nanocomposites were prepared by in situ polymerization containing 0.5, 1, 2 and 5 wt% of organically modified montmorillonite (OMMT). In order to prepare exfoliated nanocomposites a new thermally stable modifier for montmorillonite nanoparticles like chlorohexadecane triphenylphosphine (CHDTPP) was synthesized. The preparation of nanocomposites was carried out using the two-stage melt polycondensation method. As verified by TEM micrographs, the dispersion of OMMT nanoparticles into the PET matrix was homogeneous while these were dispersed in the exfoliated form, proving the effectiveness of the modifier. The influence of OMMT nanomaterials on the thermal behaviour of PET and its non-isothermal crystallization was studied. Furthermore, the crystallization kinetics of PET and its nanocomposites were investigated by DSC. The activation energy was calculated using the Friedman's method. The Avrami exponent was calculated and analyzed. The effect of OMMT nanoparticles on spherulite growth rate of PET in all nanocomposites was also evaluated using the modified Lauritzen-Hoffman equation. From all these results it was found that OMMT nanoparticles can act as nucleating agents enhancing the crystallization rate of PET. The dispersion of OMMT nanoparticles in exfoliate form plays also an important role.

Radio frequency regenerative oscillations in monolithic high-Q/V heterostructured photonic crystal cavities

International Nuclear Information System (INIS)

Yang, Jinghui; Gu, Tingyi; Zheng, Jiangjun; Wei Wong, Chee; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee

2014-01-01

We report temporal and spectral domain observation of regenerative oscillation in monolithic silicon heterostructured photonic crystals cavities with high quality factor to mode volume ratios (Q/V). The results are interpreted by nonlinear coupled mode theory (CMT) tracking the dynamics of photon, free carrier population, and temperature variations. We experimentally demonstrate effective tuning of the radio frequency tones by laser-cavity detuning and laser power levels, confirmed by the CMT simulations with sensitive input parameters

An inter-crystal scatter correction method for DOI PET image reconstruction

International Nuclear Information System (INIS)

Lam, Chih Fung; Hagiwara, Naoki; Obi, Takashi; Yamaguchi, Masahiro; Yamaya, Taiga; Murayama, Hideo

2006-01-01

New positron emission tomography (PET) scanners utilize depth-of-interaction (DOI) information to improve image resolution, particularly at the edge of field-of-view while maintaining high detector sensitivity. However, the inter-crystal scatter (ICS) effect cannot be neglected in DOI scanners due to the use of smaller crystals. ICS is the phenomenon wherein there are multiple scintillations for irradiation of a gamma photon due to Compton scatter in detecting crystals. In the case of ICS, only one scintillation position is approximated for detectors with Anger-type logic calculation. This causes an error in position detection and ICS worsens the image contrast, particularly for smaller hotspots. In this study, we propose to model an ICS probability by using a Monte Carlo simulator. The probability is given as a statistical relationship between the gamma photon first interaction crystal pair and the detected crystal pair. It is then used to improve the system matrix of a statistical image reconstruction algorithm, such as maximum likehood expectation maximization (ML-EM) in order to correct for the position error caused by ICS. We apply the proposed method to simulated data of the jPET-D4, which is a four-layer DOI PET being developed at the National Institute of Radiological Sciences. Our computer simulations show that image contrast is recovered successfully by the proposed method. (author)

Characterization studies of Silicon Photomultipliers and crystals matrices for a novel time of flight PET detector

CERN Document Server

Auffray, Etiennette; Cortinovis, Daniele; Doroud, Katayoun; Garutti, Erika; Lecoq, Paul; Liu, Zheng; Martinez, Rosana; Paganoni, Marco; Pizzichemi, Marco; Silenzi, Alessandro; Xu, Chen; Zvolský, Milan

2015-01-01

This paper describes the characterization of crystal matrices and silicon photomultiplier arrays for a novel Positron Emission Tomography (PET) detector, namely the external plate of the EndoTOFPET-US system. The EndoTOFPET-US collaboration aims to integrate Time-Of-Flight PET with ultrasound endoscopy in a novel multimodal device, capable to support the development of new biomarkers for prostate and pancreatic tumors. The detector consists in two parts: a PET head mounted on an ultrasound probe and an external PET plate. The challenging goal of 1 mm spatial resolution for the PET image requires a detector with small crystal size, and therefore high channel density: 4096 LYSO crystals individually readout by Silicon Photomultipliers (SiPM) make up the external plate. The quality and properties of these components must be assessed before the assembly. The dark count rate, gain, breakdown voltage and correlated noise of the SiPMs are measured, while the LYSO crystals are evaluated in terms of light yield and en...

arXiv Test beam measurement of the first prototype of the fast silicon pixel monolithic detector for the TT-PET project

CERN Document Server

Paolozzi, L.; Benoit, M.; Cardarelli, R.; Débieux, S.; Forshaw, D.; Hayakawa, D.; Iacobucci, G.; Kaynak, M.; Miucci, A.; Nessi, M.; Ratib, O.; Ripiccini, E.; Rücker, H.; Valerio, P.; Weber, M.

2018-04-12

The TT-PET collaboration is developing a PET scanner for small animals with  30 ps  time-of-flight resolution and sub-millimetre 3D detection granularity. The sensitive element of the scanner is a monolithic silicon pixel detector based on state-of-the-art SiGe BiCMOS technology. The first ASIC prototype for the TT-PET was produced and tested in the laboratory and with minimum ionizing particles. The electronics exhibit an equivalent noise charge below  600 e− RMS  and a pulse rise time of less than  2 ns , in accordance with the simulations. The pixels with a capacitance of  0.8 pF  were measured to have a detection efficiency greater than  99%  and, although in the absence of the post-processing, a time resolution of approximately  200 ps .

Imaging performance of a full-ring prototype PET-MRI system based on four-layer DOI-PET detectors integrated with a RF coil

Energy Technology Data Exchange (ETDEWEB)

Nishikido, Fumihiko; Tashima, Hideaki [National Institute of Radiological Sciences, Chiba (Japan); Suga, Mikio [Chiba University, Chiba (Japan); Inadama, Naoko; Eiji, Yoshida; Obata, Takayuki; Yamaya, Taiga [National Institute of Radiological Sciences, Chiba (Japan)

2015-05-18

We are developing a PET system integrated with a birdcage RF-coil for PET-MRI in order to realize both high sensitivity and high spatial resolution of the PET image by using the 4-layered depth-of-interaction (DOI) PET detector. We constructed a full-ring prototype system and evaluated performances, especially imaging performance, of the prototype system in simultaneous measurement. The prototype system consists of eight four-layer DOI-PET detectors and a prototype birdcage RF-coil developed for the proposed system. The PET detectors consist of six monolithic multi-pixel photon counter array (S11064-050P), a readout circuit, fourlayer DOI scintillator arrays and a shielding box made of 35 μm thick copper foil. The crystal array consists of 2.0 mm x 2.0 mm x 5.0 mm LYSO crystals arranged in 38 x 6 x 4 layer. The RF-coil has eight coil elements and the eight PET detectors are positioned at each element gap. The diameter of the RF-coil elements is 261 mm. We conducted performance tests of the prototype system with a 3.0 T MRI (MAGNETOM Verio). Only the PET detectors, the RF-coil and the cables were in an MRI room during measurements. A data acquisition system and power supplies for the MPPCs and preamplifiers were outside the MRI room and connected to all the detectors through a penetration panel. As a result, the spatial resolutions of a Na-22 point source in the PET image were lower than 1.6 mm in whole the FOV due to the DOI capability. In addition, the influence of the simultaneous measurements on the PET performance is negligible. On the other hand, the SNR of the phantom image in the magnitude images was degraded from 259.7 to 209.4 due to noise contamination from the power supplies.

Imaging performance of a full-ring prototype PET-MRI system based on four-layer DOI-PET detectors integrated with a RF coil

International Nuclear Information System (INIS)

Nishikido, Fumihiko; Tashima, Hideaki; Suga, Mikio; Inadama, Naoko; Eiji, Yoshida; Obata, Takayuki; Yamaya, Taiga

2015-01-01

We are developing a PET system integrated with a birdcage RF-coil for PET-MRI in order to realize both high sensitivity and high spatial resolution of the PET image by using the 4-layered depth-of-interaction (DOI) PET detector. We constructed a full-ring prototype system and evaluated performances, especially imaging performance, of the prototype system in simultaneous measurement. The prototype system consists of eight four-layer DOI-PET detectors and a prototype birdcage RF-coil developed for the proposed system. The PET detectors consist of six monolithic multi-pixel photon counter array (S11064-050P), a readout circuit, fourlayer DOI scintillator arrays and a shielding box made of 35 μm thick copper foil. The crystal array consists of 2.0 mm x 2.0 mm x 5.0 mm LYSO crystals arranged in 38 x 6 x 4 layer. The RF-coil has eight coil elements and the eight PET detectors are positioned at each element gap. The diameter of the RF-coil elements is 261 mm. We conducted performance tests of the prototype system with a 3.0 T MRI (MAGNETOM Verio). Only the PET detectors, the RF-coil and the cables were in an MRI room during measurements. A data acquisition system and power supplies for the MPPCs and preamplifiers were outside the MRI room and connected to all the detectors through a penetration panel. As a result, the spatial resolutions of a Na-22 point source in the PET image were lower than 1.6 mm in whole the FOV due to the DOI capability. In addition, the influence of the simultaneous measurements on the PET performance is negligible. On the other hand, the SNR of the phantom image in the magnitude images was degraded from 259.7 to 209.4 due to noise contamination from the power supplies.

Non-isothermal crystallization kinetic of poly(ethylene terephthalate)/fumed silica (PET/SiO2) prepared by in situ polymerization

International Nuclear Information System (INIS)

Antoniadis, G.; Paraskevopoulos, K.M.; Bikiaris, D.; Chrissafis, K.

2010-01-01

A number of poly(ethylene terephthalate) (PET) nanocomposites were prepared by in situ polymerization using different amounts (0.5, 1, 2, 3 and 4 wt%) of fumed silica (SiO 2 ). The polymerization of PET was carried out by the two-stage melt polycondensation method. From DSC studies it was found that the melting point of the nanocomposites was shifted slightly to higher temperatures by the addition of SiO 2 till 3 wt% while for PET-4 wt% SiO 2 nanocomposite the melting point was reduced. As the amount of SiO 2 was increased the crystallization became faster, and there was, also, a shifting of the temperature of the crystallization peak to higher values, this being evidence that SiO 2 can act as nucleating agent. At higher content (3 and 4 wt%) the temperature of the crystallization peak is lower than that of PET-2 wt% SiO 2 due to the formation of crosslinked macromolecules. The activation energy is calculated with the Friedman's method. PET/SiO 2 samples present lower activation energy compared to that of neat PET, except those of PET-4% SiO 2 , in which the activation energy have a maximum value for α = 0.8 probably due to the second crystallization peak. Extensive crystallization studies by using Avrami, Ozawa and Malek methods verified that PET and its nanocomposites must be crystallized by two mechanisms with different activation energies taking place in different degrees of crystallization.

High resolution detectors based on continuous crystals and SiPMs for small animal PET

International Nuclear Information System (INIS)

Cabello, J.; Barrillon, P.; Barrio, J.; Bisogni, M.G.; Del Guerra, A.; Lacasta, C.; Rafecas, M.; Saikouk, H.; Solaz, C.; Solevi, P.; La Taille, C. de; Llosá, G.

2013-01-01

Sensitivity and spatial resolution are the two main factors to maximize in emission imaging. The improvement of one factor deteriorates the other with pixelated crystals. In this work we combine SiPM matrices with monolithic crystals, using an accurate γ-ray interaction position determination algorithm that provides depth of interaction. Continuous crystals provide higher sensitivity than pixelated crystals, while an accurate interaction position determination does not degrade the spatial resolution. Monte Carlo simulations and experimental data show good agreement both demonstrating sub-millimetre intrinsic spatial resolution. A system consisting in two rotating detectors in coincidence is currently under operation already producing tomographic images

A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

Energy Technology Data Exchange (ETDEWEB)

Kato, T., E-mail: katou.frme.8180@asagi.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Yamamoto, S. [Kobe City College of Technology, 8-3, Gakuenhigashimati, Nishi-ku, Kobe-shi, Hyougo 651-2194 (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

2013-01-21

We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm{sup 2} and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×10{sup 5} at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu,Y){sub 2}(SiO{sub 4})O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm{sup 3} crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm{sup 2} pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a {sup 137}Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET). -- Highlights: ► We developed a newly designed large-area monolithic MPPC array. ► We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. ► We fabricated gamma-ray camera consisting of the MPPC array and submillimeter pixelized LYSO and GGAG scintillators. ► In

Characterization of highly multiplexed monolithic PET / gamma camera detector modules

Science.gov (United States)

Pierce, L. A.; Pedemonte, S.; DeWitt, D.; MacDonald, L.; Hunter, W. C. J.; Van Leemput, K.; Miyaoka, R.

2018-04-01

PET detectors use signal multiplexing to reduce the total number of electronics channels needed to cover a given area. Using measured thin-beam calibration data, we tested a principal component based multiplexing scheme for scintillation detectors. The highly-multiplexed detector signal is no longer amenable to standard calibration methodologies. In this study we report results of a prototype multiplexing circuit, and present a new method for calibrating the detector module with multiplexed data. A 50 × 50 × 10 mm3 LYSO scintillation crystal was affixed to a position-sensitive photomultiplier tube with 8 × 8 position-outputs and one channel that is the sum of the other 64. The 65-channel signal was multiplexed in a resistive circuit, with 65:5 or 65:7 multiplexing. A 0.9 mm beam of 511 keV photons was scanned across the face of the crystal in a 1.52 mm grid pattern in order to characterize the detector response. New methods are developed to reject scattered events and perform depth-estimation to characterize the detector response of the calibration data. Photon interaction position estimation of the testing data was performed using a Gaussian Maximum Likelihood estimator and the resolution and scatter-rejection capabilities of the detector were analyzed. We found that using a 7-channel multiplexing scheme (65:7 compression ratio) with 1.67 mm depth bins had the best performance with a beam-contour of 1.2 mm FWHM (from the 0.9 mm beam) near the center of the crystal and 1.9 mm FWHM near the edge of the crystal. The positioned events followed the expected Beer–Lambert depth distribution. The proposed calibration and positioning method exhibited a scattered photon rejection rate that was a 55% improvement over the summed signal energy-windowing method.

Simulation study of LYSO crystal pixels for In-Beam TOF-PET prototype

International Nuclear Information System (INIS)

Chen Ze; Hu Zhengguo; Chen Jinda; Zhang Xiuling

2014-01-01

In-beam TOF-PET is currently the only feasible method implemented for in-situ and noninvasive monitoring of the precision of the treatment in highly conformal ion radiotherapy. It ensures the safety of patient and accurate implementation of treatment plan. Therefore, we intent to carry out the development of In-beam TOF-PET prototype, which is made of LYSO crystal, for ion radiotherapy. LYSO crystal has perfect properties such as high light yield, fast decay time, good energy and time resolution, which makes it a good candidate. In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection and energy resolution is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte Carlo simulations play an important role in guiding research in detector designs and popular software such as Gate now include models of light transport in scintillators. This study uses Gate software to investigate the influence of crystal length and wrapping materials to the light collection. Accurate physical modeling of scintillation detection process, from scintillation light generation through detection, is devised and performed for varying detector attributes, such as the crystal pixel length, light yield, decay time, attenuation length and surface treatment. The dependence of light output and energy resolution is studied and compared with experiment results. The results show that LYSO pixel with length of 5 mm has better light yield and energy resolution, meanwhile prove that it is possible to accurately simulate the light output using Gate. (authors)

Experimental study of a depth-encoding PET detector inserting horizontal-striped glass between crystal layers

Science.gov (United States)

Yang, J.; Kim, K. B.; Choi, Y.; Kang, J.

2018-04-01

A depth-encoding positron emission tomography (PET) detector inserting a horizontal-striped glass between pixilated scintillation crystal layers was developed and experimentally evaluated. The detector consists of 2-layers of 4×4 LYSO array arranged with a 3.37 mm pitch. Horizontal-striped glasses with 1×4 array with different thickness of 3, 4 and 5 mm were inserted between top- and bottom-crystal layers. Bottom surface of bottom-layer was optically coupled to a 4×4 GAPD array. Sixteen output signals from DOI-PET detector were multiplexed by modified resistive charge division (RCD) networks and multiplexed signals were fed into custom-made charge-sensitive preamplifiers. The four amplified signals were digitized and recorded by the custom-made DAQ system based on FPGA. The four digitized outputs were post-processed and converted to flood histograms for each interaction event. Experimental results revealed that all crystal pixels were clearly identified on the 2D flood histogram without overlapping. Patterns of the 2D flood histogram were constituted with arrangements of [bottom–top–bottom–top–\\ldots–top–bottom–top–bottom] crystal responses in X-direction. These could be achieved by employing horizontal-striped glass that controlled the extent of light dispersion towards the X-direction in crystal layers for generation of a different position mapping for each layer and the modified RCD network that controls degree of charge sharing in readout electronics for reduction of identification error. This study demonstrated the proposed DOI-PET detector can extract the 3D γ-ray interaction position without considerable performance degradation of PET detector from the 2D flood histogram.

An investigation on continuous depth-of-interaction detection using a monolithic scintillator with single-ended readout

International Nuclear Information System (INIS)

Zhang, H; Zhou, R; Yang, C

2014-01-01

PET detectors with depth-of-interaction (DOI) capability have been studied to improve imaging resolution widely over the world. Since discrete DOI and continuous DOI detection with dual-ended readout technology have their respective limitations, we in this work focus on the continuous DOI detection with single-ended readout using a monolithic LSO scintillator and a multi-pixel photodetector. Based on a non-linear least squares data fitting method and Geant4 simulation, we studied the relationship between the spatial resolution of gamma positioning and the pixel number of photodetector. The results show that for a pixel number larger than 6x6, the positioning spatial resolution does not become significantly better when increasing the pixel number moreover. Another aspect studied is the effect of crystal thickness on the spatial resolution. Increasing the thickness of crystal leads to higher detection efficiency but lower spatial resolution

Time resolution deterioration with increasing crystal length in a TOF-PET system

CERN Document Server

Gundacker, S; Auffray, E; Jarron, P; Meyer, T; Lecoq, P

2014-01-01

Highest time resolution in scintillator based detectors is becoming more and more important. In medical detector physics L(Y)SO scintillators are commonly used for time of flight positron emission tomography (TOF-PET). Coincidence time resolutions (CTRs) smaller than 100 ps FWHM are desirable in order to improve the image signal to noise ratio and thus give benefit to the patient by shorter scanning times. Also in high energy physics there is the demand to improve the timing capabilities of calorimeters down to 10 ps. To achieve these goals it is important to study the whole chain, i.e. the high energy particle interaction in the crystal, the scintillation process itself, the scintillation light transfer in the crystal, the photodetector and the electronics. Time resolution measurements for a PET like system are performed with the time-over-threshold method in a coincidence setup utilizing the ultra-fast amplifier-discriminator NINO. With 2×2×3 mm3 LSO:Ce codoped 0.4%Ca crystals coupled to commercially avai...

Thermal oxidative degradation behaviours of flame-retardant thermotropic liquid crystal copolyester/PET blends

International Nuclear Information System (INIS)

Du Xiaohua; Zhao Chengshou; Wang Yuzhong; Zhou Qian; Deng Yi; Qu Minghai; Yang Bing

2006-01-01

The flame retardancy and the thermal oxidative degradation behaviors of the blend of poly(ethylene terephthalate) (PET) with a kind of phosphorus-containing thermotropic liquid crystal copolyester (TLCP) with high flame retardancy (limited oxygen index, 70%) have been investigated by oxygen index test (LOI), UL-94 rating and thermogravimetric analysis (TGA) in air. The results show that TLCP can dramatically improve the flame retardancy and the melt dripping behavior of PET. Moreover, the apparent activation energies of thermal oxidative degradation of the blends were evaluated using Kissinger and Flynn-Wall-Ozawa methods. It is found that addition of TLCP improve thermal stability and restrain thermal decomposition of PET in air, especially at the primary degradation stage. Py-GC/MS analysis shows that there are remarkable changes in the pyrolysis products when TLCP are blended into PET. The interaction between TLCP and PET has changed their thermal oxidative degradation mechanism

Geo-PET: A novel generic organ-pet for small animal organs and tissues

Science.gov (United States)

Sensoy, Levent

reconstruct tomographic images. Results demonstrate good agreement between the simulation and the prototype. Our detector system with pixelated crystals is able to separate small objects as close as 1.25 mm apart, whereas spatial resolution converges to the theoretical limit of 1.6 mm (half the size of the smallest detecting element), which is to comparable to the spatial resolution of the existing commercial small animal PET systems. Better system spatial resolution is achievable with new generation SiPM detector boards with 1 mm x 1 mm cell dimensions. We demonstrate through Monte Carlo simulations that it is possible to achieve sub-millimeter spatial image resolution (0.7 mm for our scanner) in complex objects using monolithic crystals and exploiting the light-sharing mechanism among the neighboring detector cells. Results also suggest that scanner (or object) rotation minimizes artifacts arising from poor angular sampling, which is even more significant in smaller PET designs as the gaps between the sensitive regions of the detector have a more exaggerated effect on the overall reconstructed image quality when the design is more compact. Sensitivity of the system, on the other hand, can be doubled by adding two additional detector heads resulting in a, fully closed, 4? geometry.

Crystal identification for a dual-layer-offset LYSO based PET system via Lu-176 background radiation and mean shift algorithm

Science.gov (United States)

Wei, Qingyang; Ma, Tianyu; Xu, Tianpeng; Zeng, Ming; Gu, Yu; Dai, Tiantian; Liu, Yaqiang

2018-01-01

Modern positron emission tomography (PET) detectors are made from pixelated scintillation crystal arrays and readout by Anger logic. The interaction position of the gamma-ray should be assigned to a crystal using a crystal position map or look-up table. Crystal identification is a critical procedure for pixelated PET systems. In this paper, we propose a novel crystal identification method for a dual-layer-offset LYSO based animal PET system via Lu-176 background radiation and mean shift algorithm. Single photon event data of the Lu-176 background radiation are acquired in list-mode for 3 h to generate a single photon flood map (SPFM). Coincidence events are obtained from the same data using time information to generate a coincidence flood map (CFM). The CFM is used to identify the peaks of the inner layer using the mean shift algorithm. The response of the inner layer is deducted from the SPFM by subtracting CFM. Then, the peaks of the outer layer are also identified using the mean shift algorithm. The automatically identified peaks are manually inspected by a graphical user interface program. Finally, a crystal position map is generated using a distance criterion based on these peaks. The proposed method is verified on the animal PET system with 48 detector blocks on a laptop with an Intel i7-5500U processor. The total runtime for whole system peak identification is 67.9 s. Results show that the automatic crystal identification has 99.98% and 99.09% accuracy for the peaks of the inner and outer layers of the whole system respectively. In conclusion, the proposed method is suitable for the dual-layer-offset lutetium based PET system to perform crystal identification instead of external radiation sources.

The melt growth of large LuAP single crystals for PET scanners

International Nuclear Information System (INIS)

Petrosyan, Ashot; Ovanesyan, Karine; Shirinyan, Grigory; Butaeva, Tatyana; Derdzyan, Marina; Pedrini, Christian; Dujardin, Christophe; Garnier, Nicolas; Kamenskikh, Irina

2005-01-01

Performance properties of LuAP, a material of highly promising potential for future PET scanners, are presented, as they relate to crystal growth and composition. The light yield measured in 2x2x10 mm 3 elements with 0.4-0.5% Ce and cut from large size crystals (100 mm long and 15 mm in diameter) grown by the Bridgman technique is improved to 40% LSO. The ratio between light yield measured in vertical and horizontal arrangements in the best crystals is near 90%. The role of chemical purity in respect to divalent impurities is studied

Monolithic all-PM femtosecond Yb-doped fiber laser using photonic bandgap fibers

DEFF Research Database (Denmark)

Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

2009-01-01

We present a monolithic Yb fiber laser, dispersion managed by an all-solid photonic bandgap fiber, and pulse compressed in a hollow-core photonic crystal fiber. The laser delivers 9 nJ, 275-fs long pulses at 1035 nm.......We present a monolithic Yb fiber laser, dispersion managed by an all-solid photonic bandgap fiber, and pulse compressed in a hollow-core photonic crystal fiber. The laser delivers 9 nJ, 275-fs long pulses at 1035 nm....

Development of a Single Detector Ring Micro Crystal Element Scanner: QuickPET II

Directory of Open Access Journals (Sweden)

Robert S. Miyaoka

2005-04-01

Full Text Available This article describes a single ring version of the micro crystal element scanner (MiCES and investigation of its spatial resolution imaging characteristics for mouse positron emission tomography (PET imaging. This single ring version of the MiCES system, referred to as QuickPET II, consists of 18 MiCE detector modules mounted as a single ring in a vertical gantry. The system has a 5.76-cm transverse field of view and a 1.98-cm axial field of view. In addition to the scanner and data acquisition system, we have developed an iterative reconstruction that includes a model of the system's detector response function. Evaluation images of line sources and mice have been acquired. Using filtered backprojection, the resolution for a reconstructed line source has been measured at 1.2 mm full width at half maximum. F-18-2-fluoro-2-deoxyglucose mouse PET images are provided. The result shows that QuickPET II has the imaging characteristics to support high-resolution, static mouse PET studies using 18-F labeled compounds.

AX-PET: A novel PET concept with G-APD readout

CERN Document Server

Heller, M; Casella, C; Chesi, E; De Leo, R; Dissertori, G; Fanti, V; Gillam, J E; Joram, C; Lustermann, W; Nappi, E; Oliver, J F; Pauss, F; Rafecas, M; Rudge, A; Ruotsalainen, U; Schinzel, D; Schneider, T; Seguinot, J; Solevi, P; Stapnes, S; Tuna, U; Weilhammer, P

2012-01-01

The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 key and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS strips are individually read out using Geiger-mode Avalanche Photo Diodes (G-APDs). The sensitivity of such a detector can be adjusted by changing the number of layers and the resolution is defined by the crystal and strip dimensions. Two AX-PET modules were built and fully characterized in dedicated test set-ups at CERN, with point-...

Molecular Weight and Crystallization Temperature Effects on Poly(ethylene terephthalate (PET Homopolymers, an Isothermal Crystallization Analysis

Directory of Open Access Journals (Sweden)

Leonardo A. Baldenegro-Perez

2014-02-01

Full Text Available The isothermal crystallization of poly(ethylene terephthalate (PET homopolymers with different molecular weight was studied in a wide temperature range (140–230 °C using different experimental techniques. Three different morphological regions, labeled r1, r2 and r3, were distinguished as a function of crystallization temperature (Tc. In r1 (low Tc crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals. In r2 (intermediate Tc samples showed medium size spherulites composed of two distinct crystalline families (thin and thick crystals. In this temperature range, the crystallization exhibited a maximum value and it was associated with a high content of secondary crystals. In r3 (high Tc, samples presented considerable amorphous zones and regions consisting of oversized spherulites containing only thick crystals. Time-resolved wide-angle X-ray diffraction measurements, using synchrotron radiation, indicated a rapid evolution of the crystalline degree within the second region, in contrast with the quite slow evolution observed in the third region. On the other hand, by small-angle X-ray scattering (SAXS and time-resolved SAXS experiment, it was found that the long period (L as well as the lamellar thickness (lc increase as a function of Tc, corroborating the formation of the thickest crystals in the third region. From all these observations, a morphological model was proposed for each region.

Monolithic I-Beam Crystal Monochromator

Energy Technology Data Exchange (ETDEWEB)

Bagnasco, John

2001-10-16

Curved crystal, focusing monochromators featuring cubed-root thickness profiles typically employ side-clamped cooling to reduce thermally induced overall bend deformation of the crystal. While performance is improved, residual bend deformation is often an important limiting factor in the monochromator performance. A slightly asymmetric ``I-beam'' crystal cross section with cubed-root flange profiles has been developed to further reduce this effect. Physical motivation, finite-element modeling evaluation and performance characteristics of this design are discussed. Reduction of high mounting stress at the fixed end of the crystal required the soldering of an Invar support fixture to the crystal. Detailed descriptions of this process along with its performance characteristics are also presented.

Monolithic stabilized Yb-fiber All-PM laser directly delivering nJ-level femtosecond pulses

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

2008-01-01

We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality.......We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality....

Experimental Validation of an Efficient Fan-Beam Calibration Procedure for k-Nearest Neighbor Position Estimation in Monolithic Scintillator Detectors

Science.gov (United States)

Borghi, Giacomo; Tabacchini, Valerio; Seifert, Stefan; Schaart, Dennis R.

2015-02-01

Monolithic scintillator detectors can achieve excellent spatial resolution and coincidence resolving time. However, their practical use for positron emission tomography (PET) and other applications in the medical imaging field is still limited due to drawbacks of the different methods used to estimate the position of interaction. Common statistical methods for example require the collection of an extensive dataset of reference events with a narrow pencil beam aimed at a fine grid of reference positions. Such procedures are time consuming and not straightforwardly implemented in systems composed of many detectors. Here, we experimentally demonstrate for the first time a new calibration procedure for k-nearest neighbor ( k-NN) position estimation that utilizes reference data acquired with a fan beam. The procedure is tested on two detectors consisting of 16 mm ×16 mm ×10 mm and 16 mm ×16 mm ×20 mm monolithic, Ca-codoped LSO:Ce crystals and digital photon counter (DPC) arrays. For both detectors, the spatial resolution and the bias obtained with the new method are found to be practically the same as those obtained with the previously used method based on pencil-beam irradiation, while the calibration time is reduced by a factor of 20. Specifically, a FWHM of 1.1 mm and a FWTM of 2.7 mm were obtained using the fan-beam method with the 10 mm crystal, whereas a FWHM of 1.5 mm and a FWTM of 6 mm were achieved with the 20 mm crystal. Using a fan beam made with a 4.5 MBq 22Na point-source and a tungsten slit collimator with 0.5 mm aperture, the total measurement time needed to acquire the reference dataset was 3 hours for the thinner crystal and 2 hours for the thicker one.

Silicon Photomultipliers and Monolithic Scintillators for Time-of-Flight PET

NARCIS (Netherlands)

Seifert, S.

2012-01-01

Positron emission tomography (PET) is a nuclear medical imaging modality. Its aim is to visualize the 3-dimensional distribution of a radiopharmaceutical (also called the tracer) within a patient (clinical PET) or test-animal (in case of preclinical investigations). The information that can be

Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

Energy Technology Data Exchange (ETDEWEB)

Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2014-11-17

We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

Paul Lecoq assembles a read head made with special crystals for a PET (positron emission tomography) scanner. He is the initiator of the Crystal Clear collaboration, which aims to transfer crystals developed at CERN to applications in medical imaging.

CERN Multimedia

Maximilien Brice

2004-01-01

Paul Lecoq assembles a read head made with special crystals for a PET (positron emission tomography) scanner. He is the initiator of the Crystal Clear collaboration, which aims to transfer crystals developed at CERN to applications in medical imaging.

Highly-stable monolithic femtosecond Yb-fiber laser system based on photonic crystal fibers

DEFF Research Database (Denmark)

Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

2010-01-01

in the oscillator cavity for dispersion balancing and nonlinear optical limiting, and another one is used for low nonlinearity final pulse recompression. The chirped-pulse amplification and recompression of the 232-fs, 45-pJ/pulse oscillator output yields a final direct fiber-end delivery of 7.3-nJ energy pulses......A self-starting, passively stabilized, monolithic all polarizationmaintaining femtosecond Yb-fiber master oscillator / power amplifier with very high operational and environmental stability is demonstrated. The system is based on the use of two different photonic crystal fibers. One is used...... of around 297 fs duration. Our laser shows exceptional stability. No Q-switched modelocking events were detected during 4-days long observation. An average fluctuation of only 7.85 · 10−4 over the mean output power was determined as a result of more than 6-hours long measurement. The laser is stable towards...

Exceptionally stable and hierarchically porous self-standing zeolite monolith based on a solution-mediated and solid-state transformation synergistic mechanism

Energy Technology Data Exchange (ETDEWEB)

Do, Manh Huy [Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Zhejiang University, Hangzhou 310027, Zhejiang (China); College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China); Institute of Chemical Technology, Vietnamese Academy of Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh (Viet Nam); Cheng, Dang-guo, E-mail: dgcheng@zju.edu.cn [College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China); Chen, Fengqiu [Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Zhejiang University, Hangzhou 310027, Zhejiang (China); College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhan, Xiaoli [College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang (China)

2015-11-15

Although many strategies exist for fabricating hierarchical zeolite monolith, it is still challenging to synthesize pure hierarchical zeolite monolith with intracrystalline meso-/macropores and stability suitable for industrial application in a general and efficient process. Here we describe a simple quasi-solid gel crystallization route to prepare hierarchical self-standing ZSM-5 zeolite monolith via the use of Na{sup +} and OH{sup −} as counterions to modify the breaking and remaking of T–O–T (T = Si or Al) bonds. X-ray diffraction (XRD), scanning electron microcopy (SEM), transmission electron microscopy (TEM), laser scan confocal microscopy (LSCM), N{sub 2} adsorption–desorption, mercury porosimetry, solid-state nuclear magnetic resonance (NMR), and compression mechanical testing were applied to elucidate the structure and mechanical stability of the obtained monolith. The self-standing monolith is composed of self-interconnected meso-/macroporous MFI crystals with tunable intracrystalline meso-/macropores and possesses an unusually mechanical stability with a crushing strength of 5.01 MPa. Combined with controllable structure of the defect-free membrane layer on the monolith top, the self-standing zeolite monolith should widen their potential applications. - Highlights: • Hierarchical self-standing MFI zeolite monoliths were synthesized via a facile method. • Na{sup +} and OH{sup −} are used as counterions for breaking and remaking of T–O–T (T = Si or Al) bonds. • Hierarchical self-standing MFI zeolite monoliths result from zeolite crystal intergrowth. • Self-standing zeolite monolith has an excellent mechanical stability with tunable intracrystalline meso-/macropores.

Model-Based Normalization of a Fractional-Crystal Collimator for Small-Animal PET Imaging.

Science.gov (United States)

Li, Yusheng; Matej, Samuel; Karp, Joel S; Metzler, Scott D

2017-05-01

Previously, we proposed to use a coincidence collimator to achieve fractional-crystal resolution in PET imaging. We have designed and fabricated a collimator prototype for a small-animal PET scanner, A-PET. To compensate for imperfections in the fabricated collimator prototype, collimator normalization, as well as scanner normalization, is required to reconstruct quantitative and artifact-free images. In this study, we develop a normalization method for the collimator prototype based on the A-PET normalization using a uniform cylinder phantom. We performed data acquisition without the collimator for scanner normalization first, and then with the collimator from eight different rotation views for collimator normalization. After a reconstruction without correction, we extracted the cylinder parameters from which we generated expected emission sinograms. Single scatter simulation was used to generate the scattered sinograms. We used the least-squares method to generate the normalization coefficient for each LOR based on measured, expected and scattered sinograms. The scanner and collimator normalization coefficients were factorized by performing two normalizations separately. The normalization methods were also verified using experimental data acquired from A-PET with and without the collimator. In summary, we developed a model-base collimator normalization that can significantly reduce variance and produce collimator normalization with adequate statistical quality within feasible scan time.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Compensation Methods for Non-uniform and Incomplete Data Sampling in High Resolution PET with Multiple Scintillation Crystal Layers

International Nuclear Information System (INIS)

Lee, Jae Sung; Kim, Soo Mee; Lee, Dong Soo; Hong, Jong Hong; Sim, Kwang Souk; Rhee, June Tak

2008-01-01

To establish the methods for sinogram formation and correction in order to appropriately apply the filtered backprojection (FBP) reconstruction algorithm to the data acquired using PET scanner with multiple scintillation crystal layers. Formation for raw PET data storage and conversion methods from listmode data to histogram and sinogram were optimized. To solve the various problems occurred while the raw histogram was converted into sinogram, optimal sampling strategy and sampling efficiency correction method were investigated. Gap compensation methods that is unique in this system were also investigated. All the sinogram data were reconstructed using 2D filtered backprojection algorithm and compared to estimate the improvements by the correction algorithms. Optimal radial sampling interval and number of angular samples in terms of the sampling theorem and sampling efficiency correction algorithm were pitch/2 and 120, respectively. By applying the sampling efficiency correction and gap compensation, artifacts and background noise on the reconstructed image could be reduced. Conversion method from the histogram to sinogram was investigated for the FBP reconstruction of data acquired using multiple scintillation crystal layers. This method will be useful for the fast 2D reconstruction of multiple crystal layer PET data

Properties of PET/PLA Electrospun Blends

Science.gov (United States)

Li, Kevin; Cebe, Peggy

2012-02-01

Electrospun membranes were fabricated from poly(ethylene terephthalate), PET, co-spun with poly(lactic acid), PLA. The PLA contained 2% of the D-isomer, which served to limit the overall degree of crystallinity. Membranes were deposited from blended solutions of PET/PLA in hexafluoroisopropanol. The PET/PLA composition ranged from 0/100, 75/25, 50/50, 25/75, and 100/0. Electrospun membranes were made using either a static flat plate or a rotating wheel as the counter electrode, yielding unoriented mats or highly oriented tapes, respectively. We report on our investigation of the crystallinity, crystal perfection, and mechanical properties of these materials using differential scanning calorimetry, wide and small angle X-ray scattering, and dynamic mechanical analysis. In particular, we study the ability of one blend component (PET) to crystallize in the presence of existing crystals of the second blend component (PLA) which crystallizes first and at a lower temperature than PET.

A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

Energy Technology Data Exchange (ETDEWEB)

Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D. [National Security Technologies, LLC, Livermore, California 94550 (United States); Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

2016-11-15

We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of R{sub I} at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous R{sub I} behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting R{sub I} for this range of curvature and spectral energies.

A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

International Nuclear Information System (INIS)

Haugh, M. J.; Jacoby, K. D.; Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B.

2016-01-01

We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of R I at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous R I behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting R I for this range of curvature and spectral energies.

Monolithic photonic crystals created by partial coalescence of core-shell particles.

Science.gov (United States)

Lee, Joon-Seok; Lim, Che Ho; Yang, Seung-Man; Kim, Shin-Hyun

2014-03-11

Colloidal crystals and their derivatives have been intensively studied and developed during the past two decades due to their unique photonic band gap properties. However, complex fabrication procedures and low mechanical stability severely limit their practical uses. Here, we report stable photonic structures created by using colloidal building blocks composed of an inorganic core and an organic shell. The core-shell particles are convectively assembled into an opal structure, which is then subjected to thermal annealing. During the heat treatment, the inorganic cores, which are insensitive to heat, retain their regular arrangement in a face-centered cubic lattice, while the organic shells are partially fused with their neighbors; this forms a monolithic structure with high mechanical stability. The interparticle distance and therefore stop band position are precisely controlled by the annealing time; the distance decreases and the stop band blue shifts during the annealing. The composite films can be further treated to give a high contrast in the refractive index. The inorganic cores are selectively removed from the composite by wet etching, thereby providing an organic film containing regular arrays of air cavities. The high refractive index contrast of the porous structure gives rise to pronounced structural colors and high reflectivity at the stop band position.

Modelling a multi-crystal detector block for PET

International Nuclear Information System (INIS)

Carroll, L.R.; Nutt, R.; Casey, M.

1985-01-01

A simple mathematical model describes the performance of a modular detector ''block'' which is a key component in an advanced, high-resolution PET Scanner. Each block contains 32 small bismuth germanate (BGO) crystals coupled to four photomultiplier tubes (PMTs) through a coded light pipe. AT each PMT cathode the charge released for 511 keV coincidence events may be characterized as Poisson random variables in which the variance grows as the mean of the observed current. Given the light from BGO, one must; arrange the best coding - the distribution of light to the four PMTs, specify an optimum decoding scheme for choosing the correct crystal location from a noisy ensemble of PMT currents, and estimate the average probability of error. The statistical fluctuation or ''noise'' becomes decoupled from the ''signal'' and can be regarded as independent, additive components with zero mean and unit variance. Moreover, the envelope of the transformed noise distribution approximates very closely a normal (Gaussian) distribution with variance = 1. Specifying the coding and decoding strategy becomes a problem of signalling through a channel corrupted by additive, white, Gaussian noise; a classic problem long since solved within the context of Communication Engineering using geometry: i.e. distance, volume, angle, inner product, etc., in a linear space of higher dimension

Sensitivity recovery for the AX-PET prototype using inter-crystal scattering events

CERN Document Server

Gillam, John E; Oliver, Josep F; Casella, Chiara; Heller, Matthieu; Joram, Christian; Rafecas, Magdalena

2014-01-01

The development of novel detection devices and systems such as the AX-positron emission tomography (PET) demonstrator often introduce or increase the measurement of atypical coincidence events such as inter-crystal scattering (ICS). In more standard systems, ICS events often go undetected and the small measured fraction may be ignored. As the measured quantity of such events in the data increases, so too does the importance of considering them during image reconstruction. Generally, treatment of ICS events will attempt to determine which of the possible candidate lines of response (LoRs) correctly determine the annihilation photon trajectory. However, methods of assessment often have low success rates or are computationally demanding. In this investigation alternative approaches are considered. Experimental data was taken using the AX-PET prototype and a NEMA phantom. Three methods of ICS treatment were assessed-each of which considered all possible candidate LoRs during image reconstruction. Maximum likeliho...

Simultaneous acquisition of multislice PET and MR images: initial results with a MR-compatible PET scanner.

Science.gov (United States)

Catana, Ciprian; Wu, Yibao; Judenhofer, Martin S; Qi, Jinyi; Pichler, Bernd J; Cherry, Simon R

2006-12-01

PET and MRI are powerful imaging techniques that are largely complementary in the information they provide. We have designed and built a MR-compatible PET scanner based on avalanche photodiode technology that allows simultaneous acquisition of PET and MR images in small animals. The PET scanner insert uses magnetic field-insensitive, position-sensitive avalanche photodiode (PSAPD) detectors coupled, via short lengths of optical fibers, to arrays of lutetium oxyorthosilicate (LSO) scintillator crystals. The optical fibers are used to minimize electromagnetic interference between the radiofrequency and gradient coils and the PET detector system. The PET detector module components and the complete PET insert assembly are described. PET data were acquired with and without MR sequences running, and detector flood histograms were compared with the ones generated from the data acquired outside the magnet. A uniform MR phantom was also imaged to assess the effect of the PET detector on the MR data acquisition. Simultaneous PET and MRI studies of a mouse were performed ex vivo. PSAPDs can be successfully used to read out large numbers of scintillator crystals coupled through optical fibers with acceptable performance in terms of energy and timing resolution and crystal identification. The PSAPD-LSO detector performs well in the 7-T magnet, and no visible artifacts are detected in the MR images using standard pulse sequences. The first images from the complete system have been successfully acquired and reconstructed, demonstrating that simultaneous PET and MRI studies are feasible and opening up interesting possibilities for dual-modality molecular imaging studies.

Development of compact DOI-measurable PET detectors for simultaneous PET/MR Imaging

Energy Technology Data Exchange (ETDEWEB)

Shao, Yiping; Sun, Xishan [University of Texas MD Anderson Cancer Center (United States); Lou, Kai [Rice University (United States)

2015-05-18

It is critically needed yet challenging to develop compact PET detectors with high sensitivity and uniform, high imaging resolution for improving the performance of simultaneous PET/MR imaging, particularly for an integrated/inserted small-bore system. Using the latest “edge-less” SiPM arrays for DOI measurement using the design of dual-ended-scintillator readout, we developed several compact PET detectors suited for PET/MR imaging. Each detector consists of one LYSO array with each end coupled to a SiPM array. Multiple detectors can be seamlessly tiled together along all sides to form a large detector panel. Detectors with 1.5x1.5 and 2.0x2.0 mm crystals at 20 or 30 mm lengths were studied. Readout of individual SiPM or capacitor-based signal multiplexing was used to transfer 3D interaction position-coded analog signals through flexible-print-circuit cables to dedicated ASIC frontend electronics to output digital timing pulses that encode interaction information. These digital pulses can be transferred to, through standard LVDS cables, and decoded by a FPGA-based data acquisition positioned outside the MRI scanner for coincidence event selection. Initial detector performance measurement shows excellent crystal identification even with 30 mm long crystals, ~18% and 2.8 ns energy and timing resolutions, and around 2-3 mm DOI resolution. A large size detector panel can be scaled up with these modular detectors and different PET systems can be flexibly configured with the scalable readout electronics and data acquisition, providing an important design advantage for different system and application requirements. It is expected that standard shielding of detectors, electronics and signal transfer lines can be applied for simultaneous PET/MR imaging applications, with desired DOI measurement capability to enhance the PET performance and image quality.

Development of compact DOI-measurable PET detectors for simultaneous PET/MR Imaging

International Nuclear Information System (INIS)

Shao, Yiping; Sun, Xishan; Lou, Kai

2015-01-01

It is critically needed yet challenging to develop compact PET detectors with high sensitivity and uniform, high imaging resolution for improving the performance of simultaneous PET/MR imaging, particularly for an integrated/inserted small-bore system. Using the latest “edge-less” SiPM arrays for DOI measurement using the design of dual-ended-scintillator readout, we developed several compact PET detectors suited for PET/MR imaging. Each detector consists of one LYSO array with each end coupled to a SiPM array. Multiple detectors can be seamlessly tiled together along all sides to form a large detector panel. Detectors with 1.5x1.5 and 2.0x2.0 mm crystals at 20 or 30 mm lengths were studied. Readout of individual SiPM or capacitor-based signal multiplexing was used to transfer 3D interaction position-coded analog signals through flexible-print-circuit cables to dedicated ASIC frontend electronics to output digital timing pulses that encode interaction information. These digital pulses can be transferred to, through standard LVDS cables, and decoded by a FPGA-based data acquisition positioned outside the MRI scanner for coincidence event selection. Initial detector performance measurement shows excellent crystal identification even with 30 mm long crystals, ~18% and 2.8 ns energy and timing resolutions, and around 2-3 mm DOI resolution. A large size detector panel can be scaled up with these modular detectors and different PET systems can be flexibly configured with the scalable readout electronics and data acquisition, providing an important design advantage for different system and application requirements. It is expected that standard shielding of detectors, electronics and signal transfer lines can be applied for simultaneous PET/MR imaging applications, with desired DOI measurement capability to enhance the PET performance and image quality.

Monoliths in Bioprocess Technology

Directory of Open Access Journals (Sweden)

Vignesh Rajamanickam

2015-04-01

Full Text Available Monolithic columns are a special type of chromatography column, which can be used for the purification of different biomolecules. They have become popular due to their high mass transfer properties and short purification times. Several articles have already discussed monolith manufacturing, as well as monolith characteristics. In contrast, this review focuses on the applied aspect of monoliths and discusses the most relevant biomolecules that can be successfully purified by them. We describe success stories for viruses, nucleic acids and proteins and compare them to conventional purification methods. Furthermore, the advantages of monolithic columns over particle-based resins, as well as the limitations of monoliths are discussed. With a compilation of commercially available monolithic columns, this review aims at serving as a ‘yellow pages’ for bioprocess engineers who face the challenge of purifying a certain biomolecule using monoliths.

Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

Energy Technology Data Exchange (ETDEWEB)

Nishikido, Fumihiko, E-mail: funis@nirs.go.j [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Inadama, Naoko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Oda, Ichiro [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kitamura, Keishi [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Murayama, Hideo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2010-09-21

Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6x6x4 array of 1.46x1.46 mm{sup 2}x4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

International Nuclear Information System (INIS)

Nishikido, Fumihiko; Inadama, Naoko; Oda, Ichiro; Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga; Kitamura, Keishi; Murayama, Hideo

2010-01-01

Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6x6x4 array of 1.46x1.46 mm 2 x4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

Clinical applications of PET/CT

International Nuclear Information System (INIS)

Le Ngoc Ha

2011-01-01

The purpose of this article is to review the evolution of PET, PET/CT focusing on the technical aspects, PET radiopharmaceutical developments and current clinical applications as well. The newest technologic advances have been reviewed, including improved crystal design, acquisition modes, reconstruction algorithms, etc. These advancements will continue to improve contrast, decrease noise, and increase resolution. Combined PET/CT system provides faster attenuation correction and useful anatomic correlation to PET functional information. A number of new radiopharmaceuticals used for PET imaging have been developed, however, FDG have been considered as the principal PET radiotracer. The current clinical applications of PET and PET/CT are widespread and include oncology, cardiology and neurology. (author)

Thermal and tensile properties of alumina filled PET nanocomposites

Science.gov (United States)

Nikam, Pravin N.; Deshpande, Vineeta D.

2018-05-01

In the present investigation, nanocomposites of poly(ethylene terephathalate)(PET) with different content (0 to 5 wt.%) of alumina nanoparticles (n-Al2O3) were prepared by melt-extrusion technique. Morphological characterization of samples was examined by transmission electron microscopy (TEM). Morphological analysis revealed that degree of dispersion of alumina nanoparticles (ANPs) was increased at lower content (i.e. upto 2 wt.%), which observed by TEM. Thermal and tensile measurements were carried out using and differential scanning calorimetry (DSC) and universal testing machine (UTM). The thermal analysis showed that the glass transition termperature (Tg), melting temperature (Tm), crystallization temperature (Tc) of PET/alumina nanocomposites (PNCs) were higher than neat PET (PET0). The heat enthalpy (ΔHm) of crystallization for PNCs was increased compared to PET0, which indicates that degree of crystallinity of PNCs also increased compared to PET0. The half-time (t0.5) of crystallization of PNCs were decreased compared to PET0 which indicates that the incorporation of ANPs nucleate the PET molecular chains and allowing the easily crystallization during nonisothermal process. The tensile analysis revealed that the tensile elastic modulus (i.e. Young's modulus) of PNCs increased almost linearly with increasing the content of ANPs while tensile elongation at break decreased nonlinearly. The tensile strength of PNCs increased with a 1 wt.% of ANPs whereas the higher content of ANPs decreased the tensile strength.

The system of the designing for PET detectors

International Nuclear Information System (INIS)

Fang Zongliang

2006-01-01

PET stands for Positron Emission Tomography, a new nuclear medicine imaging device. PET detector is the key of PET. This paper introduces a system of the designing for PET detector. The system can be used to design various PET detector. A PET detector BLOCK with 8 x 8 crystals has been designed and built by this system. (authors)

The MINDView brain PET detector, feasibility study based on SiPM arrays

Energy Technology Data Exchange (ETDEWEB)

González, Antonio J., E-mail: agonzalez@i3m.upv.es [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Majewski, Stan [Radiology Research, Department of Radiology, University of Virginia, VA 22903 (United States); Sánchez, Filomeno [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Aussenhofer, Sebastian [NORAS MRI products GmbH, Hochberg (Germany); Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F. [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain); Pani, Roberto; Bettiol, Marco; Fabbri, Andrea [Department of Molecular Medicine, Sapienza University of Rome (Italy); Bert, Julien; Visvikis, Dimitris [Université de Bretagne Occidentale, Brest (France); Jackson, Carl; Murphy, John; O’Neill, Kevin [SensL Technologies, Cork (Ireland); Benlloch, Jose M. [Institute for Instrumentation in Molecular Imaging (I3M), 46022 Valencia (Spain)

2016-05-11

The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm{sup 2} active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

New developments in PET detector technology

International Nuclear Information System (INIS)

Niu Lingxin; Zhao Shujun; Zhang Bin; Liu Haojia

2010-01-01

The researches on PET detector are always active and innovative area. The research direction of PET detector includes improving performances of scintillator-based detectors, investigating new detectors suitable for multi-modality imaging (e.g. PET/CT and PET/MRI), meeting requirements of TOF and DOI technologies and boosting the development of the technologies. In this paper, new developments in PET detector technology about scintillation crystal, photodetector and semiconductor detector is introduced. (authors)

Performance of a PET detector module utilizing an array of silicon photodiodes to identify the crystal of interaction

International Nuclear Information System (INIS)

Moses, W.W.; Derenzo, S.E.; Nutt, R.; Digby, W.M.; Williams, C.W.; Andreaco, M.

1993-01-01

The authors initial performance results for a new multi-layer PET detector module consisting of an array of 3 mm square by 30 mm deep BGO crystals coupled on one end to a single photomultiplier tube and on the opposite end to an array of 3 mm square silicon photodiodes. The photomultiplier tube provides an accurate timing pulse and energy discrimination for all the crystals in the module, while the silicon photodiodes identify the crystal of interaction. When a single BGO crystal at +25 C is excited with 511 keV photons, the authors measure a photodiode signal centered at 700 electrons (e - ) with noise of 375 e - fwhm. When a four crystal/photodiode module is excited with a collimated line source of 511 keV photons, the crystal of interaction is correctly identified 82% of the time. The misidentification rate can be greatly reduced and an 8 x 8 crystal/photodiode module constructed by using thicker depletion layer photodiodes or cooling to 0 C

Imaging results and TOF studies with axial PET detectors

Science.gov (United States)

Joram, Christian

2013-12-01

We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the field of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations (PET concept making use of the novel digital SiPM detectors by Philips. After reproducing comparable energy and spatial resolution on a small digital AX-PET set-up with 100 mm long crystals, we demonstrated a coincidence resolving time of about 210 ps FWHM.

2D imaging simulations of a small animal PET scanner with DOI measurement. jPET-RD

International Nuclear Information System (INIS)

Yamaya, Taiga; Hagiwara, Naoki

2005-01-01

We present a preliminary study on the design of a high sensitivity small animal depth of interaction (DOI)-PET scanner: jPET-RD (for Rodents with DOI detectors), which will contribute to molecular imaging. The 4-layer DOI block detector for the jPET-RD that consists of scintillation crystals (1.4 mm x 1.4 mm x 4.5 mm) and a flat panel position-sensitive photomultiplier tube (52 mm x 52 mm) was previously proposed. In this paper, we investigate imaging performance of the jPET-RD through numerical simulations. The scanner has a hexagonal geometry with a small diameter and a large axial aperture. Therefore DOI information is expected to improve resolution uniformity in the whole field of view (FOV). We simulate the scanner for various parameters of the number of DOI channels and the crystal length. Simulated data are reconstructed using the maximum likelihood expectation maximization with accurate system modeling. The trade-off results between background noise and spatial resolution show that only shortening the length of crystal does not improve the trade-off at all, and that 4-layer DOI information improves uniformity of spatial resolution in the whole FOV. Excellent performance of the jPET-RD can be expected based on the numerical simulation results. (author)

Scanner calibration of a small animal PET camera based on continuous LSO crystals and flat panel PSPMTs

International Nuclear Information System (INIS)

Benlloch, J.M.; Carrilero, V.; Gonzalez, A.J.; Catret, J.; Lerche, Ch.W.; Abellan, D.; Garcia de Quiros, F.; Gimenez, M.; Modia, J.; Sanchez, F.; Pavon, N.; Ros, A.; Martinez, J.; Sebastia, A.

2007-01-01

We have constructed a small animal PET with four identical detector modules, each consisting of a continuous LYSO crystal attached to a Position Sensitive Photomultiplier Tube (PSPMT). The dimensions of the continuous crystal are 50x50 mm 2 and 10 mm thickness. The modules are separated 11 cm between each other in the scanner. In this paper we discuss the method used for the calibration of the camera for this special system with continuous detectors. We also present the preliminary values for the main performance parameters such as spatial and energy resolution, and sensitivity of the system

Development of scintillation materials for PET scanners

CERN Document Server

Korzhik, Mikhail; Annenkov, Alexander N; Borissevitch, Andrei; Dossovitski, Alexei; Missevitch, Oleg; Lecoq, Paul

2007-01-01

The growing demand on PET methodology for a variety of applications ranging from clinical use to fundamental studies triggers research and development of PET scanners providing better spatial resolution and sensitivity. These efforts are primarily focused on the development of advanced PET detector solutions and on the developments of new scintillation materials as well. However Lu containing scintillation materials introduced in the last century such as LSO, LYSO, LuAP, LuYAP crystals still remain the best PET species in spite of the recent developments of bright, fast but relatively low density lanthanum bromide scintillators. At the same time Lu based materials have several drawbacks which are high temperature of crystallization and relatively high cost compared to alkali-halide scintillation materials. Here we describe recent results in the development of new scintillation materials for PET application.

Role of the substrate in monolithic AlGaAs nonlinear nanoantennas

Directory of Open Access Journals (Sweden)

Gili Valerio Flavio

2017-06-01

Full Text Available We report the effect of the aluminum oxide substrate on the emission of monolithic AlGaAs-on-insulator nonlinear nanoantennas. By coupling nonlinear optical measurements with electron diffraction and microscopy observations, we find that the oxidation-induced stress causes negligible crystal deformation in the AlGaAs nanostructures and only plays a minor role in the polarization state of the harmonic field. This result highlights the reliability of the wet oxidation of thick AlGaAs optical substrates and further confirms the bulk χ(2 origin of second harmonic generation at 1.55 μm in these nanoantennas, paving the way for the development of AlGaAs-on-insulator monolithic metasurfaces.

Energy spectra analysis of the four-layer DOI detector for the brain PET scanner: jPET-D4

International Nuclear Information System (INIS)

Yoshida, Eiji; Kitamura, Keishi; Tsuda, Tomoaki; Shibuya, Kengo; Yamaya, Taiga; Inadama, Naoko; Hasegawa, Tomoyuki; Murayama, Hideo

2006-01-01

A depth of interaction (DOI) detector is being developed for the brain PET scanner, jPET-D4. We introduce a light output correction procedure to compensate for variations among the crystal elements in the DOI detector. Under uniform irradiation with 511 keV gamma rays, we estimate the light output of each crystal element by identifying each crystal element, and generate a look-up table (LUT) for light output correction. We evaluate the energy resolution of all crystal elements. The energy resolution of 16% is achieved after light output correction for all crystal elements. The DOI detector can correct light output variations that are related to the DOI. We analyze the crystal position dependence of the energy spectra due to inter-crystal scattering among the multiple crystal elements in the DOI detector. It is highly possible that gamma rays interacting with central crystal elements in the crystal array are absorbed by surrounding crystal elements and the Compton part of the energy spectrum is decreased. Inter-crystal scattering has less impact on the energy resolution of the DOI detector

Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

Science.gov (United States)

Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

2011-01-01

This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system. PMID:21335649

Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET.

Science.gov (United States)

Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

2011-03-21

This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ± 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ± 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ± 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes-as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

Dedicated brain PET system of PET/MR for brain research

International Nuclear Information System (INIS)

Cheng, Li; Liu, Yaqiang; Ma, Tianyu; Wang, Shi; Wei, Qingyang; Xu, Tianpeng

2015-01-01

This work is to replace PET ring in human brain PET/MR system with a dedicated wearable PET insert, aimed at improving both patient feasibility and system performance for brain imaging. The designed PET/MR system includes two parts: the inside parts, including a radio frequency (RF) coil and PET ring, are mounted on patient’s head, and the outside part, a MR imager, is dependent of patient. The RF coil is the innermost layer, surrounded by an outer PET-ring layer. They are supported by a MRcompatible structure. And both RF coil and PET detectors are placed inside a standard clinical 3-T MR imager. From the design of the system we can infer that some advantages can be achieved. First, high sensitivity will be achieved with the same amount crystals as the PET ring is more close to region-of-interest area, at a reduced cost. Second, by using a 2-layer depth of interaction (DOI) detector, the parallax effect can be minimized. The resolution will benefit from short positron range caused by magnetic field and smaller ring diameter will also reduce the effect of non-collinearity. Thirdly, as the PET ring is mounted on head, impact of patient motion will be reduced.

Dedicated brain PET system of PET/MR for brain research

Energy Technology Data Exchange (ETDEWEB)

Cheng, Li; Liu, Yaqiang; Ma, Tianyu; Wang, Shi; Wei, Qingyang; Xu, Tianpeng [Institute of Medical Physics, Department of Engineering Physics, Tsinghua University, Beijing (China)

2015-05-18

This work is to replace PET ring in human brain PET/MR system with a dedicated wearable PET insert, aimed at improving both patient feasibility and system performance for brain imaging. The designed PET/MR system includes two parts: the inside parts, including a radio frequency (RF) coil and PET ring, are mounted on patient’s head, and the outside part, a MR imager, is dependent of patient. The RF coil is the innermost layer, surrounded by an outer PET-ring layer. They are supported by a MRcompatible structure. And both RF coil and PET detectors are placed inside a standard clinical 3-T MR imager. From the design of the system we can infer that some advantages can be achieved. First, high sensitivity will be achieved with the same amount crystals as the PET ring is more close to region-of-interest area, at a reduced cost. Second, by using a 2-layer depth of interaction (DOI) detector, the parallax effect can be minimized. The resolution will benefit from short positron range caused by magnetic field and smaller ring diameter will also reduce the effect of non-collinearity. Thirdly, as the PET ring is mounted on head, impact of patient motion will be reduced.

Simultaneous PET and MR imaging

International Nuclear Information System (INIS)

Yiping Shao; Cherry, Simon R.; Meadors, Ken; Siegel, Stefan; Silverman, Robert W.; Farahani, Keyvan; Marsden, Paul K.

1997-01-01

We have developed a prototype PET detector which is compatible with a clinical MRI system to provide simultaneous PET and MR imaging. This single-slice PET system consists of 48 2x2x10mm 3 LSO crystals in a 38 mm diameter ring configuration that can be placed inside the receiver coil of the MRI system, coupled to three multi-channel photomultipliers housed outside the main magnetic field via 4 m long and 2 mm diameter optical fibres. The PET system exhibits 2 mm spatial resolution, 41% energy resolution at 511 keV and 20 ns timing resolution. Simultaneous PET and MR phantom images were successfully acquired. (author)

Spatial resolution evaluation with a pair of two four-layer DOI detectors for small animal PET scanner: jPET-RD

Energy Technology Data Exchange (ETDEWEB)

Nishikido, Fumihiko [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)], E-mail: funis@nirs.go.jp; Tsuda, Tomoaki [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Yoshida, Eiji; Inadama, Naoko; Shibuya, Kengo; Yamaya, Taiga [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Kitamura, Keishi [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Takahashi, Kei [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Graduate School of Science and Technology, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba-shi, Chiba 263-8522 (Japan); Ohmura, Atsushi [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Graduate School of Advanced Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555 (Japan); Murayama, Hideo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)

2008-01-01

We are developing a small animal PET scanner, 'jPET-RD' to achieve high sensitivity as well as high spatial resolution by using four-layer depth-of-interaction (DOI) detectors. The jPET-RD is designed with two detector rings. Each detector ring is composed of six DOI detectors arranged hexagonally. The diameter of the field-of-view (FOV) is 8.8 cm, which is smaller than typical small animal PET scanners on the market now. Each detector module consists of a crystal block and a 256-channel flat panel position-sensitive photomultiplier tube. The crystal block, consisting of 32x32x4 crystal (4096 crystals, each 1.46 mmx1.46 mmx4.5 mm) and a reflector, is mounted on the 256ch FP-PMT. In this study, we evaluated the spatial resolution of reconstructed images with the evaluation system of two four-layer DOI detectors which consist of 32x32x4 LYSO (Lu: 98%, Y: 2%) crystals coupled on the 256ch FP-PMT by using RTV rubber. The spatial resolution of 1.5 mm was obtained at the center of the FOV by the filtered back projection. The spatial resolution, better than 2 mm in the whole FOV, was also achieved with DOI while the spatial resolution without DOI was degraded to 3.3 mm.

Spatial resolution evaluation with a pair of two four-layer DOI detectors for small animal PET scanner: jPET-RD

International Nuclear Information System (INIS)

Nishikido, Fumihiko; Tsuda, Tomoaki; Yoshida, Eiji; Inadama, Naoko; Shibuya, Kengo; Yamaya, Taiga; Kitamura, Keishi; Takahashi, Kei; Ohmura, Atsushi; Murayama, Hideo

2008-01-01

We are developing a small animal PET scanner, 'jPET-RD' to achieve high sensitivity as well as high spatial resolution by using four-layer depth-of-interaction (DOI) detectors. The jPET-RD is designed with two detector rings. Each detector ring is composed of six DOI detectors arranged hexagonally. The diameter of the field-of-view (FOV) is 8.8 cm, which is smaller than typical small animal PET scanners on the market now. Each detector module consists of a crystal block and a 256-channel flat panel position-sensitive photomultiplier tube. The crystal block, consisting of 32x32x4 crystal (4096 crystals, each 1.46 mmx1.46 mmx4.5 mm) and a reflector, is mounted on the 256ch FP-PMT. In this study, we evaluated the spatial resolution of reconstructed images with the evaluation system of two four-layer DOI detectors which consist of 32x32x4 LYSO (Lu: 98%, Y: 2%) crystals coupled on the 256ch FP-PMT by using RTV rubber. The spatial resolution of 1.5 mm was obtained at the center of the FOV by the filtered back projection. The spatial resolution, better than 2 mm in the whole FOV, was also achieved with DOI while the spatial resolution without DOI was degraded to 3.3 mm

Low-loss polarization-maintaining fusion splicing of single-mode fibers and hollow-core photonic crystal fibers, relevant for monolithic fiber laser pulse compression

DEFF Research Database (Denmark)

Kristensen, Jesper Toft; Houmann, Andreas; Liu, Xiaomin

2008-01-01

of the splicing process. We also demonstrate that the higher splice loss compromises the PM properties of the splice. Our splicing technique was successfully applied to the realization of a low-loss, environmentally stable monolithic PM fiber laser pulse compressor, enabling direct end-of-the-fiber femtosecond......We report on highly reproducible low-loss fusion splicing of polarization-maintaining single-mode fibers (PM-SMFs) and hollow-core photonic crystal fibers (HC-PCFs). The PM-SMF-to-HC-PCF splices are characterized by the loss of 0.62 ± 0.24 dB, and polarization extinction ratio of 19 ± 0.68 d...... pulse delivery...

Performance characteristics of 3D GSO PET/CT scanner (Philips GEMINI PET/CT)

International Nuclear Information System (INIS)

Kim, Jin Su; Lee, Jae Sung; Lee, Byeong Il; Lee, Dong Soo; Chung, June Key; Lee, Myung Chul

2004-01-01

Philips GEMINI is a newly introduced whole-body GSO PET/CT scanner. In this study, performance of the scanner including spatial resolution, sensitivity, scatter fraction, noise equivalent count ratio (NECR) was measured utilizing NEMA NU2-2001 standard protocol and compared with performance of LSO, BGO crystal scanner. GEMINI is composed of the Philips ALLEGRO PET and MX8000 D multi-slice CT scanners. The PET scanner has 28 detector segments which have an array of 29 by 22 GSO crystals (4*6*20 mm), covering axial FOV of 18 cm. PET data to measure spatial resolution, sensitivity, scatter fraction, and NECR were acquired in 3D mode according to the NEMA NU2 protocols (coincidence window: 8 ns, energy window : 409∼664 keV). For the measurement of spatial resolution, images were reconstructed with FBP using ramp filter and an iterative reconstruction algorithm, 3D RAMLA. Data for sensitivity measurement were acquired using NEMA sensitivity phantom filled with F-18 solution and surrounded by 1∼5 aluminum sleeves after we confirmed that dead time loss did not exceed 1%. To measure NECR and scatter fraction, 1110 MBq of F-18 solution was injected into a NEMA scatter phantom with a length of 70 cm and dynamic scan with 20-min frame duration was acquired for 7 half-lives. Oblique sinograms were collapsed into transaxial slices using single slice rebinning method, and true to background (scatter + random) ratio for each slice and frame was estimated. Scatter fraction was determined by averaging the true to background ratio of last 3 frames in which the dead time loss was below 1%. Transverse and axial resolutions at 1 cm radius were (1) 5.3 and 6.5 mm (FBP), (2) 5.1 and 5.9 mm (3D RAMLA). Transverse radial, transverse tangential, and axial resolution at 10 cm were (1) 5.7, 5.7, and 7.0 mm (FBP), (2) 5.4, 5.4, and 6.4 mm (3D RAMLA). Attenuation free values of sensitivity were 3,620 counts/sec/MBq at the center of transaxial FOV and 4,324 counts/sec/MBq at 10 cm offset

Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

2008-01-01

. The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output pulse......We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror...

Scintillator studies for the HPD-PET concept

CERN Document Server

Braem, D; Ciocia, F; De Leo, R; Joram, C; Lagamba, L; Nappi, E; Séguinot, Jacques; Vilardi, I; Weilhammer, P

2007-01-01

The spatial, energy, and time resolutions of 10 cm long polished YAP:Ce and LYSO:Ce crystals have been measured. The work is part of the novel HPD-PET concept, based on a full three-dimensional, free of parallax errors, reconstruction of the γ-ray interaction point in 10–15 cm long scintillators. The effective light attenuation length, a key parameter of the HPD-PET concept, and the resolutions have been measured for various wrappings and coatings of the crystal lateral surfaces. Even if the final HPD-PET prototype could use scintillators and/or wrappings different from those tested, the results here presented prove the feasibility of the concept and provide hints on its potential capabilities.

A novel, SiPM-array-based, monolithic scintillator detector for PET

NARCIS (Netherlands)

Schaart, Dennis R.; van Dam, Herman T.; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Beekman, Freek J.; Löhner, H.

2009-01-01

Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e. g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as

Development of a PET Insert for simultaneously small animal PET/MRI

Energy Technology Data Exchange (ETDEWEB)

Wang, Yingjie; Zhang, Zhiming; Li, Daowu; Liu, Shuangquan; Wang, Peilin; Feng, Baotong; Chai, Pei; Wei, Long [Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049 (China); Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing, 100049 (China)

2015-05-18

PET/MR is a new multi-modality imaging system which provide both structural and functional information with good soft tissue imaging ability and no ionizing radiation. In recent years, PET/MR is under major progress because of the development of silicon photomultipliers (SiPM). The goal of this study is to develop a MRI compatible PET insert based on SiPM and LYSO scintillator. The PET system was constituted by the detector ring, electronics and software. The detector ring consists of 16 detector module. The inner diameter of the ring was 151 mm, the external diameter was 216 mm, which was big enough for small animal research, e.g. rat, rabbit and tupaia. The sensor of each module was 2*2 SensL SPMArraySL, coupled with an array of 14 x 14 LYSO crystals, each crystal measuring 2 mm x 2 mm 10 mm. The detector was encapsulated in a copper box for light and magnetic shielding. Resister charge multiplexing circuit was used in the front end electronics. Each detector output 8X and 8Y position signals. One summed timing signal was extracted from the common cathode of all 64 channels. All these signals were transmitted to digital electronic board by a 3 m long coaxial cable from inside of the MR to the outside. Each digital electronic board handled 8 detector modules based on FPGA to obtain the timing, position and energy information of a single event. And then these single events were sent to the coincidence processing board to produce coincidence packets which are prepared for further processing. A 0.2mCi 68Ge line source was used to do the preliminary imaging test. The image was reconstructed by 3D-OSEM algorithm. The initial result proved the system to be feasible as a PET. FDG phantom imaging and simultaneous PET/MR imaging are in progress.

Determination of the Interaction Position of Gamma Photons in Monolithic Scintillators Using Neural Network Fitting

Science.gov (United States)

Conde, P.; Iborra, A.; González, A. J.; Hernández, L.; Bellido, P.; Moliner, L.; Rigla, J. P.; Rodríguez-Álvarez, M. J.; Sánchez, F.; Seimetz, M.; Soriano, A.; Vidal, L. F.; Benlloch, J. M.

2016-02-01

In Positron Emission Tomography (PET) detectors based on monolithic scintillators, the photon interaction position needs to be estimated from the light distribution (LD) on the photodetector pixels. Due to the finite size of the scintillator volume, the symmetry of the LD is truncated everywhere except for the crystal center. This effect produces a poor estimation of the interaction positions towards the edges, an especially critical situation when linear algorithms, such as Center of Gravity (CoG), are used. When all the crystal faces are painted black, except the one in contact with the photodetector, the LD can be assumed to behave as the inverse square law, providing a simple theoretical model. Using this LD model, the interaction coordinates can be determined by means of fitting each event to a theoretical distribution. In that sense, the use of neural networks (NNs) has been shown to be an effective alternative to more traditional fitting techniques as nonlinear least squares (LS). The multilayer perceptron is one type of NN which can model non-linear functions well and can be trained to accurately generalize when presented with new data. In this work we have shown the capability of NNs to approximate the LD and provide the interaction coordinates of γ-photons with two different photodetector setups. One experimental setup was based on analog Silicon Photomultipliers (SiPMs) and a charge division diode network, whereas the second setup was based on digital SiPMs (dSiPMs). In both experiments NNs minimized border effects. Average spatial resolutions of 1.9 ±0.2 mm and 1.7 ±0.2 mm for the entire crystal surface were obtained for the analog and dSiPMs approaches, respectively.

New DOI identification approach for high-resolution PET detectors

International Nuclear Information System (INIS)

Choghadi, Amin; Takahashi, Hiroyuki; Shimazoe, Kenji

2016-01-01

Depth-of-interaction (DOI) Identification in positron emission tomography (PET) detectors is getting importance as it improves spatial resolution in both conventional and time-of-flight (TOF) PET, and coincidence time resolution (CTR) in TOF-PET. In both prototypes, spatial resolution is affected by parallax error caused by length of scintillator crystals. This long length also contributes substantial timing uncertainty to the time resolution of TOF-PET. Through DOI identification, both parallax error and the timing uncertainty caused by the length of crystal can be resolved. In this work, a novel approach to estimate DOI was investigated, enjoying the interference of absorbance spectrum of scintillator crystals with their emission spectrum. Because the absorption length is close to zero for shorter wavelengths of crystal emission spectrum, the counts in this range of spectrum highly depend on DOI; that is, higher counts corresponds to deeper interactions. The ratio of counts in this range to the total counts is a good measure to estimate DOI. In order to extract such ratio, two photodetectors for each crystal are used and an optical filter is mounted only on top of one of them. The ratio of filtered output to non-filtered output can be utilized as DOI estimator. For a 2×2×20 mm 3 GAGG:Ce scintillator, 8-mm DOI resolution achieved in our simulations. (author)

The AX-PET demonstrator-Design, construction and characterization

International Nuclear Information System (INIS)

Beltrame, P.; Bolle, E.; Braem, A.; Casella, C.; Chesi, E.; Clinthorne, N.; De Leo, R.; Dissertori, G.; Djambazov, L.; Fanti, V.; Heller, M.; Joram, C.; Kagan, H.; Lustermann, W.; Meddi, F.; Nappi, E.; Nessi-Tedaldi, F.; Oliver, J.F.; Pauss, F.; Rafecas, M.

2011-01-01

Axial PET is a novel geometrical concept for Positron Emission Tomography (PET), based on layers of long scintillating crystals axially aligned with the bore axis. The axial coordinate is obtained from arrays of wavelength shifting (WLS) plastic strips placed orthogonally to the crystals. This article describes the design, construction and performance evaluation of a demonstrator set-up which consists of two identical detector modules, used in coincidence. Each module comprises 48 LYSO crystals of 100 mm length and 156 WLS strips. Crystals and strips are readout by Geiger-mode Avalanche Photo Diodes (G-APDs). The signals from the two modules are processed by fully analog front-end electronics and recorded in coincidence by a VME-based data acquisition system. Measurements with point-like 22 Na sources, with the modules used both individually and in coincidence mode, allowed for a complete performance evaluation up to the focal plane reconstruction of point sources. The results obtained are in good agreement with expectations and proved the set-up to be ready for the next evaluation phase with PET phantoms filled with radiotracers.

Detector Position Estimation for PET Scanners.

Science.gov (United States)

Pierce, Larry; Miyaoka, Robert; Lewellen, Tom; Alessio, Adam; Kinahan, Paul

2012-06-11

Physical positioning of scintillation crystal detector blocks in Positron Emission Tomography (PET) scanners is not always exact. We test a proof of concept methodology for the determination of the six degrees of freedom for detector block positioning errors by utilizing a rotating point source over stepped axial intervals. To test our method, we created computer simulations of seven Micro Crystal Element Scanner (MiCES) PET systems with randomized positioning errors. The computer simulations show that our positioning algorithm can estimate the positions of the block detectors to an average of one-seventh of the crystal pitch tangentially, and one-third of the crystal pitch axially. Virtual acquisitions of a point source grid and a distributed phantom show that our algorithm improves both the quantitative and qualitative accuracy of the reconstructed objects. We believe this estimation algorithm is a practical and accurate method for determining the spatial positions of scintillation detector blocks.

Detector position estimation for PET scanners

International Nuclear Information System (INIS)

Pierce, Larry; Miyaoka, Robert; Lewellen, Tom; Alessio, Adam; Kinahan, Paul

2012-01-01

Physical positioning of scintillation crystal detector blocks in Positron Emission Tomography (PET) scanners is not always exact. We test a proof of concept methodology for the determination of the six degrees of freedom for detector block positioning errors by utilizing a rotating point source over stepped axial intervals. To test our method, we created computer simulations of seven Micro Crystal Element Scanner (MiCES) PET systems with randomized positioning errors. The computer simulations show that our positioning algorithm can estimate the positions of the block detectors to an average of one-seventh of the crystal pitch tangentially, and one-third of the crystal pitch axially. Virtual acquisitions of a point source grid and a distributed phantom show that our algorithm improves both the quantitative and qualitative accuracy of the reconstructed objects. We believe this estimation algorithm is a practical and accurate method for determining the spatial positions of scintillation detector blocks.

Spatial resolution limits for the isotropic-3D PET detector X’tal cube

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Eiji, E-mail: rush@nirs.go.jp; Tashima, Hideaki; Hirano, Yoshiyuki; Inadama, Naoko; Nishikido, Fumihiko; Murayama, Hideo; Yamaya, Taiga

2013-11-11

Positron emission tomography (PET) has become a popular imaging method in metabolism, neuroscience, and molecular imaging. For dedicated human brain and small animal PET scanners, high spatial resolution is needed to visualize small objects. To improve the spatial resolution, we are developing the X’tal cube, which is our new PET detector to achieve isotropic 3D positioning detectability. We have shown that the X’tal cube can achieve 1 mm{sup 3} uniform crystal identification performance with the Anger-type calculation even at the block edges. We plan to develop the X’tal cube with even smaller 3D grids for sub-millimeter crystal identification. In this work, we investigate spatial resolution of a PET scanner based on the X’tal cube using Monte Carlo simulations for predicting resolution performance in smaller 3D grids. For spatial resolution evaluation, a point source emitting 511 keV photons was simulated by GATE for all physical processes involved in emission and interaction of positrons. We simulated two types of animal PET scanners. The first PET scanner had a detector ring 14.6 cm in diameter composed of 18 detectors. The second PET scanner had a detector ring 7.8 cm in diameter composed of 12 detectors. After the GATE simulations, we converted the interacting 3D position information to digitalized positions for realistic segmented crystals. We simulated several X’tal cubes with cubic crystals from (0.5 mm){sup 3} to (2 mm){sup 3} in size. Also, for evaluating the effect of DOI resolution, we simulated several X’tal cubes with crystal thickness from (0.5 mm){sup 3} to (9 mm){sup 3}. We showed that sub-millimeter spatial resolution was possible using cubic crystals smaller than (1.0 mm){sup 3} even with the assumed physical processes. Also, the weighted average spatial resolutions of both PET scanners with (0.5 mm){sup 3} cubic crystals were 0.53 mm (14.6 cm ring diameter) and 0.48 mm (7.8 cm ring diameter). For the 7.8 cm ring diameter, spatial

Development and evaluation of a LOR-based image reconstruction with 3D system response modeling for a PET insert with dual-layer offset crystal design

International Nuclear Information System (INIS)

Zhang, Xuezhu; Thiessen, Jonathan D; Goertzen, Andrew L; Stortz, Greg; Sossi, Vesna; Thompson, Christopher J; Retière, Fabrice; Kozlowski, Piotr

2013-01-01

In this study we present a method of 3D system response calculation for analytical computer simulation and statistical image reconstruction for a magnetic resonance imaging (MRI) compatible positron emission tomography (PET) insert system that uses a dual-layer offset (DLO) crystal design. The general analytical system response functions (SRFs) for detector geometric and inter-crystal penetration of coincident crystal pairs are derived first. We implemented a 3D ray-tracing algorithm with 4π sampling for calculating the SRFs of coincident pairs of individual DLO crystals. The determination of which detector blocks are intersected by a gamma ray is made by calculating the intersection of the ray with virtual cylinders with radii just inside the inner surface and just outside the outer-edge of each crystal layer of the detector ring. For efficient ray-tracing computation, the detector block and ray to be traced are then rotated so that the crystals are aligned along the X-axis, facilitating calculation of ray/crystal boundary intersection points. This algorithm can be applied to any system geometry using either single-layer (SL) or multi-layer array design with or without offset crystals. For effective data organization, a direct lines of response (LOR)-based indexed histogram-mode method is also presented in this work. SRF calculation is performed on-the-fly in both forward and back projection procedures during each iteration of image reconstruction, with acceleration through use of eight-fold geometric symmetry and multi-threaded parallel computation. To validate the proposed methods, we performed a series of analytical and Monte Carlo computer simulations for different system geometry and detector designs. The full-width-at-half-maximum of the numerical SRFs in both radial and tangential directions are calculated and compared for various system designs. By inspecting the sinograms obtained for different detector geometries, it can be seen that the DLO crystal

X-ray crystal structure of the passenger domain of plasmid encoded toxin(Pet), an autotransporter enterotoxin from enteroaggregative Escherichia coli (EAEC)

Energy Technology Data Exchange (ETDEWEB)

Domingo Meza-Aguilar, J. [Departamento de Salud Pública Facultad de Medicina UNAM, Ciudad Universitaria Coyoacán 04510, D.F. (Mexico); Laboratorio de Patogenicidad Bacteriana, Unidad de Hemato Oncología e Investigación, Hospital Infantil de México Federico Gómez 06720, D.F. (Mexico); Fromme, Petra [Department of Chemistry and Biochemistry, Arizona State University, Physical Sciences BLDG D-102, Tempe, AZ 85287 (United States); Torres-Larios, Alfredo [Instituto de Fisiología Celular UNAM, Ciudad Universitaria Coyoacán 04510, D.F. (Mexico); Mendoza-Hernández, Guillermo [Instituto de Química UNAM, Ciudad Universitaria Coyoacán 04510, D.F (Mexico); Hernandez-Chiñas, Ulises [Departamento de Salud Pública Facultad de Medicina UNAM, Ciudad Universitaria Coyoacán 04510, D.F. (Mexico); Laboratorio de Patogenicidad Bacteriana, Unidad de Hemato Oncología e Investigación, Hospital Infantil de México Federico Gómez 06720, D.F. (Mexico); Arreguin-Espinosa de los Monteros, Roberto A. [Instituto de Química UNAM, Ciudad Universitaria Coyoacán 04510, D.F (Mexico); and others

2014-03-07

Highlights: • X-ray crystal structure of the passenger domain of Plasmid encoded toxin at 2.3 Å. • Structural differences between Pet passenger domain and EspP protein are described. • High flexibility of the C-terminal beta helix is structurally assigned. - Abstract: Autotransporters (ATs) represent a superfamily of proteins produced by a variety of pathogenic bacteria, which include the pathogenic groups of Escherichia coli (E. coli) associated with gastrointestinal and urinary tract infections. We present the first X-ray structure of the passenger domain from the Plasmid-encoded toxin (Pet) a 100 kDa protein at 2.3 Å resolution which is a cause of acute diarrhea in both developing and industrialized countries. Pet is a cytoskeleton-altering toxin that induces loss of actin stress fibers. While Pet (pdb code: 4OM9) shows only a sequence identity of 50% compared to the closest related protein sequence, extracellular serine protease plasmid (EspP) the structural features of both proteins are conserved. A closer structural look reveals that Pet contains a β-pleaded sheet at the sequence region of residues 181–190, the corresponding structural domain in EspP consists of a coiled loop. Secondary, the Pet passenger domain features a more pronounced beta sheet between residues 135 and 143 compared to the structure of EspP.

Poster - 01: LabPET II Pixelated APD-Based PET Scanner for High-Resolution Preclinical Imaging

Energy Technology Data Exchange (ETDEWEB)

Lecomte, Roger; Arpin, Louis; Beaudoin, Jean-François; Bergeron, Mélanie; Bouchard, Jonathan; Bouziri, Haithem; Cadorette, Jules; Gaudin, Émilie; Jürgensen, Nadia; Koua, Konin Calliste; Trépanier, Pierre-Yves Lauzier; Leroux, Jean-Daniel; Loignon-Houle, Francis; Njejimana, Larissa; Paillé, Maxime; Paulin, Caroline; Pepin, Catherine; Pratte, Jean-François; Samson, Arnaud; Thibaudeau, Christian [Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, Université de Sherbrooke, Université de Sherbrooke, 3IT, Université de Sherbrooke, Novalgo Inc., Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, 3IT, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, 3IT, Université de Sherbrooke (Canada); and others

2016-08-15

Purpose: LabPET II is a new generation APD-based PET scanner designed to achieve sub-mm spatial resolution using truly pixelated detectors and highly integrated parallel front-end processing electronics. Methods: The basic element uses a 4×8 array of 1.12×1.12 mm{sup 2} Lu{sub 1.9}Y{sub 0.1}SiO{sub 5}:Ce (LYSO) scintillator pixels with one-to-one coupling to a 4×8 pixelated monolithic APD array mounted on a ceramic carrier. Four detector arrays are mounted on a daughter board carrying two flip-chip, 64-channel, mixed-signal, application-specific integrated circuits (ASIC) on the backside interfacing to two detector arrays each. Fully parallel signal processing was implemented in silico by encoding time and energy information using a dual-threshold Time-over-Threshold (ToT) scheme. The self-contained 128-channel detector module was designed as a generic component for ultra-high resolution PET imaging of small to medium-size animals. Results: Energy and timing performance were optimized by carefully setting ToT thresholds to minimize the noise/slope ratio. ToT spectra clearly show resolved 511 keV photopeak and Compton edge with ToT resolution well below 10%. After correction for nonlinear ToT response, energy resolution is typically 24±2% FWHM. Coincidence time resolution between opposing 128-channel modules is below 4 ns FWHM. Initial imaging results demonstrate that 0.8 mm hot spots of a Derenzo phantom can be resolved. Conclusion: A new generation PET scanner featuring truly pixelated detectors was developed and shown to achieve a spatial resolution approaching the physical limit of PET. Future plans are to integrate a small-bore dedicated mouse version of the scanner within a PET/CT platform.

Effects of reflector and crystal surface on the performance of a depth-encoding PET detector with dual-ended readout

International Nuclear Information System (INIS)

Ren, Silin; Yang, Yongfeng; Cherry, Simon R.

2014-01-01

Purpose: Depth encoding detectors are required to improve the spatial resolution and spatial resolution uniformity of small animal positron emission tomography (PET) scanners, as well as dedicated breast and brain scanners. Depth of interaction (DOI) can be measured by using dual-ended readout of lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiodes. Inter-crystal reflectors and crystal surface treatments play important roles in determining the performance of dual-ended detectors. In this paper, the authors evaluated five LSO arrays made with three different intercrystal reflectors and with either polished or unpolished crystal surfaces. Methods: The crystal size in all arrays was 1.5 mm, which is typical of the detector size used in small animal and dedicated breast scanners. The LSO arrays were measured with dual-ended readout and were compared in terms of flood histogram, energy resolution, and DOI resolution performance. Results: The four arrays using enhanced specular reflector (ESR) and Toray reflector provided similar quality flood histograms and the array using Crystal Wrap reflector gave the worst flood histogram. The two arrays using ESR reflector provided the best energy resolution and the array using Crystal Wrap reflector yielded the worst energy resolution. All arrays except the polished ESR array provided good DOI resolution ranging from 1.9 mm to 2.9 mm. DOI resolution improved as the gradient in light collection efficiency with depth (GLCED) increased. The geometric mean energies were also calculated for these dual-ended readout detectors as an alternative to the conventional summed total energy. It was shown that the geometric mean energy is advantageous in that it provides more uniform photopeak amplitude at different depths for arrays with high GLCED, and is beneficial in event selection by allowing a fixed energy window independent of depth. A new method of DOI calculation that improved the linearity

TSD current investigations in pristine and 100 MeV Ni-ion irradiated PET/0.3 PHB polymer liquid crystal

International Nuclear Information System (INIS)

Quamara, J.K.; Singh, Nafa; Prabhavathi, T.; Sridharbabu, Y.

2002-01-01

The dielectric relaxations investigations have been carried out in pristine as well as 100 MeV 58 Ni ion irradiated (PELLETRON facility, Nuclear Science Center, New Delhi) PET/0.3 PHB PLC samples. Thermally stimulated depolarization current technique (TSDC) has been employed for this purpose. The plc samples were polarized at 180 deg C under the influence of various polarizing fields following the usual method. Three current maxima are observed around 35deg, 120deg and 155degC which are ascribed as β', β and α transitions. These transitions are mainly due to the fast reacting dipoles of PHB regions, dipolar character due to carbonyl groups in PET rich phase and to the cold crystallization of PET. The results confirm the biphasic nature of this plc. The high energy irradiation influences both β and α transitions. Increase in fluence shifts the β peak as well as α peak towards higher temperature. This confirms that high energy irradiation has not only affected the carbonyl groups but has created new phases. (author)

Estimation of position resolution for DOI-PET detector using diameter 0.2 mm WLS fibers [ANIMMA--2015-IO-x5

International Nuclear Information System (INIS)

Kaneko, Naomi; Ito, H.; Han, S.; Kawai, H.; Kodama, S.; Kobayashi, A.; Tabata, M.; Kamada, K.; Shoji, Y.; Yoshikawa, A.

2015-01-01

We have been developing a submillimeter resolution and low-cost DOI-PET detector using wavelength shifting fibers (WLSF), scintillating crystal plates and MPPCs (Hamamatsu Photonics). Conventional design of DOI-PET detectors had approximately mm 3 of resolution by using some scintillating blocks with a volume of 1 mm 3 , which detects gamma-ray. They are expensive due to difficulties in processing scintillating crystals and a large number of photo-detectors, and these technologies are likely to reach the limit of the resolution. Development of a lower cost DOI-PET detector with higher resolution is challenging to popularize the PET diagnosis. We propose two type of PET detector. One is a whole body PET system, and the other is a PET system for brain or small animals. Each PET system consists 6 blocks. The former consists of 6 layers of crystal plates with 300 mm x 300 mm x 4 mm. The latter consists of 16 crystal layers, forming 4 x 4 crystal arrays. The size of the crystal plate is 40 mm x 40 mm x 1 mm. Wavelength shifting fiber (WLSF) sheets are attached to above and up and down side of crystal planes. The whole PET system has 8 MPPCs attached on each side. For the brain PET detector, 9 WLSF fibers are attached on the each side. The expected position resolution would be less than 1 mm at the former system. We have performed an experimental performance estimation for the system component using 22 Na radioactive source. We achieved a collection efficiency of 10% using the WLSF sheet and Ce:Gd 3 (Al,Ga) 5 O 12 (GAGG) crystals at 511 keV. The linear relationship between reconstruction position and incident position was obtained, and a resolution of 0.7 mm (FWHM) for x-axis of DOI by the WLSF readout was achieved. (authors)

PET/CT: underlying physics, instrumentation, and advances.

Science.gov (United States)

Torres Espallardo, I

Since it was first introduced, the main goal of PET/CT has been to provide both PET and CT images with high clinical quality and to present them to radiologists and specialists in nuclear medicine as a fused, perfectly aligned image. The use of fused PET and CT images quickly became routine in clinical practice, showing the great potential of these hybrid scanners. Thanks to this success, manufacturers have gone beyond considering CT as a mere attenuation corrector for PET, concentrating instead on design high performance PET and CT scanners with more interesting features. Since the first commercial PET/CT scanner became available in 2001, both the PET component and the CT component have improved immensely. In the case of PET, faster scintillation crystals with high stopping power such as LYSO crystals have enabled more sensitive devices to be built, making it possible to reduce the number of undesired coincidence events and to use time of flight (TOF) techniques. All these advances have improved lesion detection, especially in situations with very noisy backgrounds. Iterative reconstruction methods, together with the corrections carried out during the reconstruction and the use of the point-spread function, have improved image quality. In parallel, CT instrumentation has also improved significantly, and 64- and 128-row detectors have been incorporated into the most modern PET/CT scanners. This makes it possible to obtain high quality diagnostic anatomic images in a few seconds that both enable the correction of PET attenuation and provide information for diagnosis. Furthermore, nowadays nearly all PET/CT scanners have a system that modulates the dose of radiation that the patient is exposed to in the CT study in function of the region scanned. This article reviews the underlying physics of PET and CT imaging separately, describes the changes in the instrumentation and standard protocols in a combined PET/CT system, and finally points out the most important

EFFECT OF INTERFACIAL ADHESION ON CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY (ETHYLENE TEREPHTHALATE)/GLASS BEAD COMPOSITES

Institute of Scientific and Technical Information of China (English)

OU Yuchun; YU Zhongzhen; ZHU Jin; LI Ge; ZHU Shanguang

1996-01-01

The interfacial adhesion between poly (ethylene terephthalate) (PET) and glass bead was investigated by scanning electron microscope and parallel-plate rheometer. Effect of interfacial adhesion on the crystallization and mechanical properties of PET/glass bead composites was also studied by differential scanning calorimeter and mechanical testers.The results obtained indicate that the glass bead has a heterogeneous nucleation effect on the PET crystallization. Although better interfacial adhesion is advantageous to the increase of the tensile strength of the composite, yet it is unfavorable to the crystallization of PET. It should be pointed out that the crystallization rate of filled PET is always higher than that of pure PET, regardless of the state of interfacial adhesion.

Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

Science.gov (United States)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

2016-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

Fibrous monolithic ceramics

International Nuclear Information System (INIS)

Kovar, D.; King, B.H.; Trice, R.W.; Halloran, J.W.

1997-01-01

Fibrous monolithic ceramics are an example of a laminate in which a controlled, three-dimensional structure has been introduced on a submillimeter scale. This unique structure allows this all-ceramic material to fail in a nonbrittle manner. Materials have been fabricated and tested with a variety of architectures. The influence on mechanical properties at room temperature and at high temperature of the structure of the constituent phases and the architecture in which they are arranged are discussed. The elastic properties of these materials can be effectively predicted using existing models. These models also can be extended to predict the strength of fibrous monoliths with an arbitrary orientation and architecture. However, the mechanisms that govern the energy absorption capacity of fibrous monoliths are unique, and experimental results do not follow existing models. Energy dissipation occurs through two dominant mechanisms--delamination of the weak interphases and then frictional sliding after cracking occurs. The properties of the constituent phases that maximize energy absorption are discussed. In this article, the authors examine the structure of Si 3 N 4 -BN fibrous monoliths from the submillimeter scale of the crack-deflecting cell-cell boundary features to the nanometer scale of the BN cell boundaries

Epitaxial Ge-crystal arrays for X-ray detection

International Nuclear Information System (INIS)

Kreiliger, T; Falub, C V; Müller, E; Känel, H von; Isa, F; Isella, G; Chrastina, D; Bergamaschini, R; Marzegalli, A; Miglio, L; Kaufmann, R; Niedermann, P; Neels, A; Dommann, A; Meduňa, M

2014-01-01

Monolithic integration of an X-ray absorber layer on a Si CMOS chip might be a potentially attractive way to improve detector performance at acceptable costs. In practice this requires, however, the epitaxial growth of highly mismatched layers on a Si-substrate, both in terms of lattice parameters and thermal expansion coefficients. The generation of extended crystal defects, wafer bowing and layer cracking have so far made it impossible to put the simple concept into practice. Here we present a way in which the difficulties of fabricating very thick, defect-free epitaxial layers may be overcome. It consists of an array of densely packed, three-dimensional Ge-crystals on a patterned Si(001) substrate. The finite gap between neighboring micron-sized crystals prevents layer cracking and substrate bowing, while extended defects are driven to the crystal sidewalls. We show that the Ge-crystals are indeed defect-free, despite the lattice misfit of 4.2%. The electrical characteristics of individual Ge/Si heterojunction diodes are obtained from in-situ measurements inside a scanning electron microscope. The fabrication of monolithically integrated detectors is shown to be compatible with Si-CMOS processing

Finite Element Modeling of Reheat Stretch Blow Molding of PET

Science.gov (United States)

Krishnan, Dwarak; Dupaix, Rebecca B.

2004-06-01

Poly (ethylene terephthalate) or PET is a polymer used as a packaging material for consumer products such as beverages, food or other liquids, and in other applications including drawn fibers and stretched films. Key features that make it widely used are its transparency, dimensional stability, gas impermeability, impact resistance, and high stiffness and strength in certain preferential directions. These commercially useful properties arise from the fact that PET crystallizes upon deformation above the glass transition temperature. Additionally, this strain-induced crystallization causes the deformation behavior of PET to be highly sensitive to processing conditions. It is thus crucial for engineers to be able to predict its performance at various process temperatures, strain rates and strain states so as to optimize the manufacturing process. In addressing these issues; a finite element analysis of the reheat blow molding process with PET has been carried out using ABAQUS. The simulation employed a constitutive model for PET developed by Dupaix and Boyce et al.. The model includes the combined effects of molecular orientation and strain-induced crystallization on strain hardening when the material is deformed above the glass transition temperature. The simulated bottles were also compared with actual blow molded bottles to evaluate the validity of the simulation.

A high resolution TOF-PET concept with axial geometry and digital SiPM readout

CERN Document Server

Casella, C; Joram, C; Schneider, T

2014-01-01

The axial arrangement of long scintillation crystals is a promising concept in PET instrumentation to address the need for optimized resolution and sensitivity. Individual crystal readout and arrays of wavelength shifter strips placed orthogonally to the crystals lead to a 3D-detection of the annihilations photons. A fully operational demonstrator scanner, developed by the AX-PET collaboration, proved the potential of this concept in terms of energy and spatial resolution as well as sensitivity. This paper describes a feasibility study, performed on axial prototype detector modules with 100 mm long LYSO crystals, read out by the novel digital Silicon Photomultipliers (dSiPM) from Philips. With their highly integrated readout electronics and excellent intrinsic time resolution, dSiPMs allow for compact, axial detector modules which may extend the potential of the axial PET concept by time of fl ight capabilities (TOF-PET). A coincidence time resolution of 211 ps (FWHM) was achieved in the coincidence of two ax...

Imaging results and TOF studies with axial PET detectors

CERN Document Server

Joram, Christian

2013-01-01

We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the held of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The Fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations ( <2 mm FWHM in all three coordinates over the complete held of view) and also demonstrated the ability to include Compton interactions (inter-cr...

Monolithic exploding foil initiator

Science.gov (United States)

Welle, Eric J; Vianco, Paul T; Headley, Paul S; Jarrell, Jason A; Garrity, J. Emmett; Shelton, Keegan P; Marley, Stephen K

2012-10-23

A monolithic exploding foil initiator (EFI) or slapper detonator and the method for making the monolithic EFI wherein the exploding bridge and the dielectric from which the flyer will be generated are integrated directly onto the header. In some embodiments, the barrel is directly integrated directly onto the header.

Demonstration of an Axial PET concept for brain and small animal imaging

CERN Document Server

Beltrame, P; Clinthorne, N; Meddi, F; Kagan, H; Braem, A; Pauss, F; Djambazov, L; Lustermann, W; Weilhammer, P; Nessi-Tedaldi, F; Dissertori, G; Renker, D; Schneider, T; Schinzel, D; De Leo, R; Bolle, E; Fanti, V; Rafecas, M; Rudge, A; Stapnes, S; Casella, C; Chesi, E; Seguinot, J; Solevi, P; Joram, C; Oliver, J F

2011-01-01

Standard Positron Emission Tomography (PET) cameras need to reach a compromise between spatial resolution and sensitivity. To overcome this limitation we developed a novel concept of PET. Our AX-PET demonstrator is made of LYSO crystals aligned along the z coordinate (patient's axis) and WLS strips orthogonally placed with respect to the crystals. This concept offers full 3D localization of the photon interaction inside the camera. Thus the spatial resolution and the sensitivity can be simultaneously improved and the reconstruction of Compton interactions inside the detector is also possible. Moreover, by means of G-APDs for reading out the photons, both from LYSO and WLS, the detector is insensitive to magnetic fields and it is then suitable to be used in a combined PET/MRI apparatus. A complete Monte Carlo simulation and dedicated reconstruction software have been developed. The two final modules, each composed of 48 crystals and 156 WLS strips, have been built and fully characterized in a dedicated test se...

Method for making a single-step etch mask for 3D monolithic nanostructures

International Nuclear Information System (INIS)

Grishina, D A; Harteveld, C A M; Vos, W L; Woldering, L A

2015-01-01

Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to etch three-dimensional monolithic nanostructures using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in a single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realized, namely cubic, tetragonal, orthorhombic, monoclinic and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns on the different surfaces can be completely independently structured and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures. (paper)

Aperture scaling effects with monolithic periodically poled lithium niobate optical parametric oscillators and generators.

Science.gov (United States)

Missey, M; Dominic, V; Powers, P; Schepler, K L

2000-02-15

We used elliptical beams to demonstrate aperture scaling effects in nanosecond single-grating and multigrating periodically poled lithium niobate (PPLN) monolithic optical parametric oscillators and generators. Increasing the cavity Fresnel number in single-grating crystals broadened both the beam divergence and the spectral bandwidth. Both effects are explained in terms of the phase-matching geometry. These effects are suppressed when a multigrating PPLN crystal is used because the individual gratings provide small effective subapertures. A flood-pumped multigrating optical parametric generator displayed a low output beam divergence and contained 19 pairs of signal and idler frequencies.

The MiniPET: a didactic PET system

International Nuclear Information System (INIS)

Pedro, R; Silva, J; Maio, A; Gurriana, L; Silva, J M; Augusto, J Soares

2013-01-01

The MiniPET project aims to design and build a small PET system. It consists of two 4 × 4 matrices of 16 LYSO scintillator crystals and two PMTs with 16 channels resulting in a low cost system with the essential functionality of a clinical PET instrument. It is designed to illustrate the physics of the PET technique and to provide a didactic platform for the training of students and nuclear imaging professionals as well as for scientific outreach. The PET modules can be configured to test for the coincidence of 511 keV gamma rays. The model has a flexible mechanical setup [1] and can simulate 14 diferent ring geometries, from a configuration with as few as 18 detectors per ring (ring radius φ=51 mm), up to a geometry with 70 detectors per ring (φ=200 mm). A second version of the electronic system [2] allowed measurement and recording of the energy deposited in 4 detector channels by photons from a 137 Cs radioactive source and by photons resulting of the annihilation of positrons from a 22 Na radioactive source. These energy spectra are used for detector performance studies, as well as angular dependency studies. In this paper, the mechanical setup, the front-end high-speed analog electronics, the digital acquisition and control electronics implemented in a FPGA, as well as the data-transfer interface between the FPGA board and a host PC are described. Recent preliminary results obtained with the 4 active channels in the prototype are also presented.

Monolithic Ytterbium All-single-mode Fiber Laser with Direct Fiber-end Delivery of nJ-level Femtosecond Pulses

DEFF Research Database (Denmark)

Turchinovich, Dmitry

2008-01-01

We demonstrate a monolithic, i.e. without any free-space coupling, all-single-mode passively modelocked Yb-fiber laser, with direct fiber-end delivery of 364−405 fs pulses of 4 nJ pulse energy using a low-loss hollow-core photonic crystal fiber compression....

Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

Energy Technology Data Exchange (ETDEWEB)

Zuo, Biao, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com; Xu, Jianquan; Sun, Shuzheng; Liu, Yue; Yang, Juping; Zhang, Li; Wang, Xinping, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com [Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

2016-06-21

Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.

The performance characteristics of the Philips Gemini PET/CT scanner

International Nuclear Information System (INIS)

O'Keefe, G.J.; Papenfuss, A.T.; Scott, A.M.; Rowe, C.C.

2002-01-01

Full text: The Department of Nuclear Medicine, Centre for PET at the ARMC is commissioning a next generation PET/CT scanner based on gadolinium silicic dioxide (GSO) crystal technology to replace the BGO crystal PET scanner that has been in operation since 1992. The Gemini PET/CT scanner is a fully 3D PET system which offers significantly increased resolution and sensitivity allowing wholebody scans in under 30 minutes. Until the late 90's, PET scanners were largely used with septa for neurological imaging and the performance characteristics of PET scanners were presented according to the NEMA-NU2-94 standard which specifically addresses the performance of PET scanners for neurological applications. PET is now largely used without septa for oncological imaging and as such, the NEMA-NU2-94 standard does not adequately reflect performance. The NEMA-NU2-2001 standard was designed to incorporate the effects of out-of-FOV activity and its contribution to performance by virtue of the increased scatter and randoms that result when performing wholebody scans without the use of septa. As part of the acceptance program of the Allegro/Gemini systems, the NEMA-NU2-2001 standard will be used to characterise the spatial resolution, sensitivity, randoms and scatter contributions and the Noise Equivalent Count rate (NECr). These results will be presented and compared with the ECAT 951/31R performance characteristics. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

PET performance evaluation of MADPET4: a small animal PET insert for a 7 T MRI scanner

Science.gov (United States)

Omidvari, Negar; Cabello, Jorge; Topping, Geoffrey; Schneider, Florian R.; Paul, Stephan; Schwaiger, Markus; Ziegler, Sibylle I.

2017-11-01

MADPET4 is the first small animal PET insert with two layers of individually read out crystals in combination with silicon photomultiplier technology. It has a novel detector arrangement, in which all crystals face the center of field of view transaxially. In this work, the PET performance of MADPET4 was evaluated and compared to other preclinical PET scanners using the NEMA NU 4 measurements, followed by imaging a mouse-size hot-rod resolution phantom and two in vivo simultaneous PET/MRI scans in a 7 T MRI scanner. The insert had a peak sensitivity of 0.49%, using an energy threshold of 350 keV. A uniform transaxial resolution was obtained up to 15 mm radial offset from the axial center, using filtered back-projection with single-slice rebinning. The measured average radial and tangential resolutions (FWHM) were 1.38 mm and 1.39 mm, respectively. The 1.2 mm rods were separable in the hot-rod phantom using an iterative image reconstruction algorithm. The scatter fraction was 7.3% and peak noise equivalent count rate was 15.5 kcps at 65.1 MBq of activity. The FDG uptake in a mouse heart and brain were visible in the two in vivo simultaneous PET/MRI scans without applying image corrections. In conclusion, the insert demonstrated a good overall performance and can be used for small animal multi-modal research applications.

Oxygen Barrier Properties and Melt Crystallization Behavior of Poly(ethylene terephthalate/Graphene Oxide Nanocomposites

Directory of Open Access Journals (Sweden)

Anna Szymczyk

2015-01-01

Full Text Available Poly(ethylene terephthalate nanocomposites with low loading (0.1–0.5 wt% of graphene oxide (GO have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for PET nanocomposite films over the neat PET is approximately factors of 2–3.3. DSC study on the nonisothermal crystallization behaviors proves that GO acts as a nucleating agent to accelerate the crystallization of PET matrix. The evolution of the lamellar nanostructure of nanocomposite and neat PET was monitored by SAXS during nonisothermal crystallization from the melt. It was found that unfilled PET and nanocomposite with the highest concentration of GO (0.5 wt% showed almost similar values of the long period (L=11.4 nm for neat PET and L=11.5 nm for PET/0.5GO.

Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding

Energy Technology Data Exchange (ETDEWEB)

Kolb, A., E-mail: armin.kolb@med.uni-tuebingen.de; Parl, C.; Liu, C. C.; Pichler, B. J. [Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, 72076 Tübingen (Germany); Mantlik, F. [Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, 72076 Tübingen, Germany and Department of Empirical Inference, Max Planck Institute for Intelligent Systems, 72076 Tübingen (Germany); Lorenz, E. [Max Planck Institute for Physics, Föhringer Ring 6, 80805 München (Germany); Renker, D. [Department of Physics, Technische Universität München, 85748 Garching (Germany)

2014-08-15

Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated {sup 18}F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 �

High-Q/V Monolithic Diamond Microdisks Fabricated with Quasi-isotropic Etching.

Science.gov (United States)

Khanaliloo, Behzad; Mitchell, Matthew; Hryciw, Aaron C; Barclay, Paul E

2015-08-12

Optical microcavities enhance light-matter interactions and are essential for many experiments in solid state quantum optics, optomechanics, and nonlinear optics. Single crystal diamond microcavities are particularly sought after for applications involving diamond quantum emitters, such as nitrogen vacancy centers, and for experiments that benefit from diamond's excellent optical and mechanical properties. Light-matter coupling rates in experiments involving microcavities typically scale with Q/V, where Q and V are the microcavity quality-factor and mode-volume, respectively. Here we demonstrate that microdisk whispering gallery mode cavities with high Q/V can be fabricated directly from bulk single crystal diamond. By using a quasi-isotropic oxygen plasma to etch along diamond crystal planes and undercut passivated diamond structures, we create monolithic diamond microdisks. Fiber taper based measurements show that these devices support TE- and TM-like optical modes with Q > 1.1 × 10(5) and V < 11(λ/n) (3) at a wavelength of 1.5 μm.

PeneloPET, a Monte Carlo PET simulation tool based on PENELOPE: features and validation

Energy Technology Data Exchange (ETDEWEB)

Espana, S; Herraiz, J L; Vicente, E; Udias, J M [Grupo de Fisica Nuclear, Departmento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid (Spain); Vaquero, J J; Desco, M [Unidad de Medicina y CirugIa Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain)], E-mail: jose@nuc2.fis.ucm.es

2009-03-21

Monte Carlo simulations play an important role in positron emission tomography (PET) imaging, as an essential tool for the research and development of new scanners and for advanced image reconstruction. PeneloPET, a PET-dedicated Monte Carlo tool, is presented and validated in this work. PeneloPET is based on PENELOPE, a Monte Carlo code for the simulation of the transport in matter of electrons, positrons and photons, with energies from a few hundred eV to 1 GeV. PENELOPE is robust, fast and very accurate, but it may be unfriendly to people not acquainted with the FORTRAN programming language. PeneloPET is an easy-to-use application which allows comprehensive simulations of PET systems within PENELOPE. Complex and realistic simulations can be set by modifying a few simple input text files. Different levels of output data are available for analysis, from sinogram and lines-of-response (LORs) histogramming to fully detailed list mode. These data can be further exploited with the preferred programming language, including ROOT. PeneloPET simulates PET systems based on crystal array blocks coupled to photodetectors and allows the user to define radioactive sources, detectors, shielding and other parts of the scanner. The acquisition chain is simulated in high level detail; for instance, the electronic processing can include pile-up rejection mechanisms and time stamping of events, if desired. This paper describes PeneloPET and shows the results of extensive validations and comparisons of simulations against real measurements from commercial acquisition systems. PeneloPET is being extensively employed to improve the image quality of commercial PET systems and for the development of new ones.

PeneloPET, a Monte Carlo PET simulation tool based on PENELOPE: features and validation

International Nuclear Information System (INIS)

Espana, S; Herraiz, J L; Vicente, E; Udias, J M; Vaquero, J J; Desco, M

2009-01-01

Monte Carlo simulations play an important role in positron emission tomography (PET) imaging, as an essential tool for the research and development of new scanners and for advanced image reconstruction. PeneloPET, a PET-dedicated Monte Carlo tool, is presented and validated in this work. PeneloPET is based on PENELOPE, a Monte Carlo code for the simulation of the transport in matter of electrons, positrons and photons, with energies from a few hundred eV to 1 GeV. PENELOPE is robust, fast and very accurate, but it may be unfriendly to people not acquainted with the FORTRAN programming language. PeneloPET is an easy-to-use application which allows comprehensive simulations of PET systems within PENELOPE. Complex and realistic simulations can be set by modifying a few simple input text files. Different levels of output data are available for analysis, from sinogram and lines-of-response (LORs) histogramming to fully detailed list mode. These data can be further exploited with the preferred programming language, including ROOT. PeneloPET simulates PET systems based on crystal array blocks coupled to photodetectors and allows the user to define radioactive sources, detectors, shielding and other parts of the scanner. The acquisition chain is simulated in high level detail; for instance, the electronic processing can include pile-up rejection mechanisms and time stamping of events, if desired. This paper describes PeneloPET and shows the results of extensive validations and comparisons of simulations against real measurements from commercial acquisition systems. PeneloPET is being extensively employed to improve the image quality of commercial PET systems and for the development of new ones.

Microfluidic devices and methods including porous polymer monoliths

Science.gov (United States)

Hatch, Anson V; Sommer, Gregory J; Singh, Anup K; Wang, Ying-Chih; Abhyankar, Vinay V

2014-04-22

Microfluidic devices and methods including porous polymer monoliths are described. Polymerization techniques may be used to generate porous polymer monoliths having pores defined by a liquid component of a fluid mixture. The fluid mixture may contain iniferters and the resulting porous polymer monolith may include surfaces terminated with iniferter species. Capture molecules may then be grafted to the monolith pores.

National Electrical Manufacturers Association NU-4 performance evaluation of the PET component of the NanoPET/CT preclinical PET/CT scanner.

Science.gov (United States)

Szanda, Istvan; Mackewn, Jane; Patay, Gergely; Major, Peter; Sunassee, Kavitha; Mullen, Gregory E; Nemeth, Gabor; Haemisch, York; Blower, Philip J; Marsden, Paul K

2011-11-01

The NanoPET/CT represents the latest generation of commercial preclinical PET/CT systems. This article presents a performance evaluation of the PET component of the system according to the National Electrical Manufacturers Association (NEMA) NU-4 2008 standard. The NanoPET/CT consists of 12 lutetium yttrium orthosilicate:cerium modular detectors forming 1 ring, with 9.5-cm axial coverage and a 16-cm animal port. Each detector crystal is 1.12 × 1.12 × 13 mm, and 1 module contains 81 × 39 of these crystals. An optical light guide transmits the scintillation light to the flat-panel multianode position-sensitive photomultiplier tubes. Analog-to-digital converter cards and a field-programmable gate array-based data-collecting card provide the readout. Spatial resolution, sensitivity, counting rate capabilities, and image quality were evaluated in accordance with the NEMA NU-4 standard. Energy and temporal resolution measurements and a mouse imaging study were performed in addition to the standard. Energy resolution was 19% at 511 keV. The spatial resolution, measured as full width at half maximum on single-slice rebinning/filtered backprojection-reconstructed images, approached 1 mm on the axis and remained below 2.5 mm in the central 5-cm transaxial region both in the axial center and at one-quarter field of view. The maximum absolute sensitivity for a point source at the center of the field of view was 7.7%. The maximum noise equivalent counting rates were 430 kcps at 36 MBq and 130 kcps at 27 MBq for the mouse- and rat-sized phantoms, respectively. The uniformity and recovery coefficients were measured with the image-quality phantom, giving good-quality images. In a mouse study with an (18)F-labeled thyroid-specific tracer, the 2 lobes of the thyroid were clearly distinguishable, despite the small size of this organ. The flexible readout system allowed experiments to be performed in an efficient manner, and the system remained stable throughout. The large number

Fully integrated monolithic opoelectronic transducer for real.time protein and DNA detection

DEFF Research Database (Denmark)

Misiakos, Konstatinos; S. Petrou, Panagiota; E. Kakabakos, Sotirios

2010-01-01

The development and testing of a portable bioanalytical device which was capable for real-time monitoring of binding assays was demonstrated. The device was based on arrays of nine optoelectronic transducers monolithically integrated on silicon chips. The optocouplers consisted of nine silicon av...... by exploiting wavelength filtering on photonic crystal engineered waveguides. The proposed miniaturized sensing device with proper packaging and accompanied by a portable instrument can find wide application as a platform for reliable and cost effective point-of-care diagnosis....

High spatial resolution measurement of depth-of-interaction of a PET LSO crystal

International Nuclear Information System (INIS)

Simon, A.; Kalinka, G.; Novak, D.; Sipos, A.; Vegh, J.; Molnar, J.

2004-01-01

Complete text of publication follows. A new type of experimental technique to investigate the depth-of-interaction (DOI) dependence in small scintillator elements designed for high-resolution animal PET [1] has been introduced at our institute, recently. A lutetium oxyorthosilicate (LSO) crystal (2x2x10 mm 3 ) was irradiated with a highly focused 2 MeV He + beam at the ATOMKI nuclear microprobe laboratory. Pulse height spectra from a photomultiplier (PMT) attached to one end of the LSO crystal were collected in list mode. Sequential scans of 1000x1000 μm 2 areas along the 10 mm long crystal were made to get high lateral resolution images of pulse height spectra at different distances from the window of the PMT. A mean pulse height algorithm was applied to each pixel to generate two dimensional intensity images and the corresponding spectra of 100 μmx1 mm areas. Representative pulse height spectra are shown in Fig. 1 for different distances between the position of irradiation and the PMT. The mean value of the pulse height spectrum describing the position of the full energy peak is a way to measure DOI effects. It is seen that the closer the DOI to the PMT-end of the crystal the higher the energy of the peak. The centre of the detected peak varies about 30 % along the lateral side of the crystal. This effect is due to the increasing number of reflections with associated loss of light when the distance between the DOI position and the light collecting PMT grows. Further these results, no difference in the light intensity was found depending on which position across (perpendicular to the length of) the crystal was irradiated with the microbeam. The obtained results of the overall DOI dependence confirm previous measurements on LSO crystals with similar geometry and wrapping but based on collimated gamma-ray irradiation. Since the present experimental setup allows obtaining data with several orders of magnitude better spatial resolution (from μm up to mm) than with

Monolithic spectrometer

Energy Technology Data Exchange (ETDEWEB)

Rajic, Slobodan (Knoxville, TN); Egert, Charles M. (Oak Ridge, TN); Kahl, William K. (Knoxville, TN); Snyder, Jr., William B. (Knoxville, TN); Evans, III, Boyd M. (Oak Ridge, TN); Marlar, Troy A. (Knoxville, TN); Cunningham, Joseph P. (Oak Ridge, TN)

1998-01-01

A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

CYBPET: a cylindrical PET system for breast imaging

Energy Technology Data Exchange (ETDEWEB)

Karimian, A. [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of) and Nuclear Research Center for Agriculture and Medicine (NRCAM-AEOI), P.O. BOX. (31485-498), Karaj, Iran, Islamic Republic of and Department of Experimental Medicine and Pathology, University of Rome, La Sapienza, Rome (Italy)]. E-mail: akarimian@nrcam.org; Thompson, C.J. [Montreal Neurological Institute, McGill University, Montreal QC (Canada); Sarkar, S. [Medical physics Department of Tehran University of Medical Sciences and (RCSTIM), Tehran (Iran, Islamic Republic of); Raisali, G. [Nuclear Research Center for Agriculture and Medicine (NRCAM-AEOI), P.O. BOX. (31485-498), Karaj (Iran, Islamic Republic of); Pani, R. [Department of Experimental Medicine and Pathology, University of Rome La Sapienza, Rome (Italy); Davilu, H. [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sardari, D. [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

2005-06-11

We propose a Cylindrical Breast PET (CYBPET) system for breast imaging with patients in the prone position. An individual pendulous breast is covered by thin plastic to provide reduced pressure fixation and surrounded by the crystals inside the CYBPET ring. Each breast is imaged separately. The rest of the body is shielded properly to minimize the contribution of scattered photons from the other breast and the rest of the body. To compare the CYBPET with whole-body PET (WB-PET) the simulations of CYBPET and a WB-PET (GE-Advance) for a 10 mm tumor inside the breast with a lesion to background (breast) activity concentration of 6 to 1 were made. The noise effective count rate (NECR) of CYBPET is about twice that of WB-PET at activity concentrations less than 3.1 {mu}Ci/cc. The spatial resolution of CYBPET is better by 25% than the WB-PET.

CYBPET: a cylindrical PET system for breast imaging

International Nuclear Information System (INIS)

Karimian, A.; Thompson, C.J.; Sarkar, S.; Raisali, G.; Pani, R.; Davilu, H.; Sardari, D.

2005-01-01

We propose a Cylindrical Breast PET (CYBPET) system for breast imaging with patients in the prone position. An individual pendulous breast is covered by thin plastic to provide reduced pressure fixation and surrounded by the crystals inside the CYBPET ring. Each breast is imaged separately. The rest of the body is shielded properly to minimize the contribution of scattered photons from the other breast and the rest of the body. To compare the CYBPET with whole-body PET (WB-PET) the simulations of CYBPET and a WB-PET (GE-Advance) for a 10 mm tumor inside the breast with a lesion to background (breast) activity concentration of 6 to 1 were made. The noise effective count rate (NECR) of CYBPET is about twice that of WB-PET at activity concentrations less than 3.1 μCi/cc. The spatial resolution of CYBPET is better by 25% than the WB-PET

Activated Carbon Fiber Monoliths as Supercapacitor Electrodes

Directory of Open Access Journals (Sweden)

Gelines Moreno-Fernandez

2017-01-01

Full Text Available Activated carbon fibers (ACF are interesting candidates for electrodes in electrochemical energy storage devices; however, one major drawback for practical application is their low density. In the present work, monoliths were synthesized from two different ACFs, reaching 3 times higher densities than the original ACFs’ apparent densities. The porosity of the monoliths was only slightly decreased with respect to the pristine ACFs, the employed PVDC binder developing additional porosity upon carbonization. The ACF monoliths are essentially microporous and reach BET surface areas of up to 1838 m2 g−1. SEM analysis reveals that the ACFs are well embedded into the monolith structure and that their length was significantly reduced due to the monolith preparation process. The carbonized monoliths were studied as supercapacitor electrodes in two- and three-electrode cells having 2 M H2SO4 as electrolyte. Maximum capacitances of around 200 F g−1 were reached. The results confirm that the capacitance of the bisulfate anions essentially originates from the double layer, while hydronium cations contribute with a mixture of both, double layer capacitance and pseudocapacitance.

Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study

International Nuclear Information System (INIS)

González, A.J.; Conde, P.; Iborra, A.; Aguilar, A.; Bellido, P.; García-Olcina, R.; Hernández, L.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A.; Torres, J.; Vidal, L.F.; Benlloch, J.M.

2015-01-01

We have developed a detector block composed by a monolithic LYSO scintillator coupled to a custom made 12×12 SiPMs array. The design is mainly focused to applications such as Positron Emission Tomography. The readout electronics is based on 3 identical and scalable Application Specific Integrated Circuits (ASIC). We have determined the main performance of the detector block namely spatial, energy, and time resolution but also the system capability to determine the photon depth of interaction, for different crystal surface treatments. Intrinsic detector spatial resolution values as good as 1.7 mm FWHM and energies of 15% for black painted crystals were measured

Monolithic solid-state lasers for spaceflight

Science.gov (United States)

Krainak, Michael A.; Yu, Anthony W.; Stephen, Mark A.; Merritt, Scott; Glebov, Leonid; Glebova, Larissa; Ryasnyanskiy, Aleksandr; Smirnov, Vadim; Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth

2015-02-01

A new solution for building high power, solid state lasers for space flight is to fabricate the whole laser resonator in a single (monolithic) structure or alternatively to build a contiguous diffusion bonded or welded structure. Monolithic lasers provide numerous advantages for space flight solid-state lasers by minimizing misalignment concerns. The closed cavity is immune to contamination. The number of components is minimized thus increasing reliability. Bragg mirrors serve as the high reflector and output coupler thus minimizing optical coatings and coating damage. The Bragg mirrors also provide spectral and spatial mode selection for high fidelity. The monolithic structure allows short cavities resulting in short pulses. Passive saturable absorber Q-switches provide a soft aperture for spatial mode filtering and improved pointing stability. We will review our recent commercial and in-house developments toward fully monolithic solid-state lasers.

Methacrylate monolithic columns functionalized with epinephrine for capillary electrochromatography applications.

Science.gov (United States)

Carrasco-Correa, Enrique Javier; Ramis-Ramos, Guillermo; Herrero-Martínez, José Manuel

2013-07-12

Epinephrine-bonded polymeric monoliths for capillary electrochromatography (CEC) were developed by nucleophilic substitution reaction of epoxide groups of poly(glycidyl-methacrylate-co-ethylenedimethacrylate) (poly(GMA-co-EDMA)) monoliths using epinephrine as nucleophilic reagent. The ring opening reaction under dynamic conditions was optimized. Successful chemical modification of the monolith surface was ascertained by in situ Raman spectroscopy characterization. In addition, the amount of epinephrine groups that was bound to the monolith surface was evaluated by oxidation of the catechol groups with Ce(IV), followed by spectrophotometric measurement of unreacted Ce(IV). About 9% of all theoretical epoxide groups of the parent monolith were bonded to epinephrine. The chromatographic behavior of the epinephrine-bonded monolith in CEC conditions was assessed with test mixtures of alkyl benzenes, aniline derivatives and substituted phenols. In comparison to the poly(GMA-co-EDMA) monoliths, the epinephrine-bonded monoliths exhibited a much higher retention and slight differences in selectivity. The epinephrine-bonded monolith was further modified by oxidation with a Ce(IV) solution and compared with the epinephrine-bonded monoliths. The resulting monolithic stationary phases were evaluated in terms of reproducibility, giving RSD values below 9% in the parameters investigated. Copyright © 2013 Elsevier B.V. All rights reserved.

Peculiarities of forming diffusion bimetallic joints of aluminum foam with a monolithic magnesium alloy

Directory of Open Access Journals (Sweden)

M. Khokhlov

2016-12-01

Full Text Available The work is carried out to determine an optimal method to obtain the welded bimetallic joints of monolithic Mg-alloy with porous Al-alloy using gallium as chemical activator and heating up to 300 °C by two different methods: long-term in vacuum oven and short-term without vacuum by passing of low voltage current. There is no microstructure change in Al-foam but indentation test records the negligible reduction of the mechanical properties. SEM showed the crystallization of two types of Mg5Ga2 and Mg2Ga inter-metallic phases in the wavy uneven diffusion zone on Mg-alloy side with significant increase of micro-hardness and Young's modulus. The narrow depth of the diffusion zone takes place in joints by short-term heating, so this method is more applicable for welding of monolithic and porous alloys at chemical activation using gallium.

PET performance and MRI compatibility evaluation of a digital, ToF-capable PET/MRI insert equipped with clinical scintillators

International Nuclear Information System (INIS)

Schug, David; Wehner, Jakob; Dueppenbecker, Peter Michael; Weissler, Bjoern; Goldschmidt, Benjamin; Schulz, Volkmar; Gebhardt, Pierre; Salomon, Andre; Kiessling, Fabian

2015-01-01

We evaluate the MR compatibility of the Hyperion-II D positron emission tomography (PET) insert, which allows simultaneous operation in a clinical magnetic resonance imaging (MRI) scanner. In contrast to previous investigations, this work aims at the evaluation of a clinical crystal configuration. An imaging-capable demonstrator with an axial field-of-view of 32 mm and a crystal-to-crystal spacing of 217.6 mm was equipped with LYSO scintillators with a pitch of 4 mm which were read out in a one-to-one coupling scheme by sensor tiles composed of digital silicon photomultipliers from Philips Digital Photon Counting (DPC 3200-22). The PET performance degradation (energy resolution and coincidence resolution time (CRT)) was evaluated during simultaneous operation of the MRI scanner. We used clinically motivated imaging sequences as well as synthetic gradient stress test sequences. Without activity of the MRI scanner, we measured for trigger scheme 1 (first photon trigger) an energy resolution of 11.4% and a CRT of 213 ps for a narrow energy (NE) window using five 22 Na point-like sources. When applying the synthetic gradient sequences, we found worst-case relative degradations of the energy resolution by 5.1% and of the CRT by 33.9%. After identifying the origin of the degradations and implementing a fix to the read-out hardware, the same evaluation revealed no degradation of the PET performance anymore even when the most demanding gradient stress tests were applied. The PET performance of the insert was initially evaluated using the point sources, a high-activity phantom and hot-rod phantoms in order to assess the spatial resolution. Trigger schemes 2–4 delivered an energy resolution of 11.4% as well and CRTs of 279 ps, 333 ps and 557 ps for the NE window, respectively. An isocenter sensitivity of 0.41% using the NE window and 0.71% with a wide energy window was measured. Using a hot-rod phantom, a spatial resolution in the order of 2 mm was demonstrated and

PET performance and MRI compatibility evaluation of a digital, ToF-capable PET/MRI insert equipped with clinical scintillators

Science.gov (United States)

Schug, David; Wehner, Jakob; Dueppenbecker, Peter Michael; Weissler, Bjoern; Gebhardt, Pierre; Goldschmidt, Benjamin; Salomon, Andre; Kiessling, Fabian; Schulz, Volkmar

2015-09-01

We evaluate the MR compatibility of the Hyperion-IID positron emission tomography (PET) insert, which allows simultaneous operation in a clinical magnetic resonance imaging (MRI) scanner. In contrast to previous investigations, this work aims at the evaluation of a clinical crystal configuration. An imaging-capable demonstrator with an axial field-of-view of 32 mm and a crystal-to-crystal spacing of 217.6 mm was equipped with LYSO scintillators with a pitch of 4 mm which were read out in a one-to-one coupling scheme by sensor tiles composed of digital silicon photomultipliers from Philips Digital Photon Counting (DPC 3200-22). The PET performance degradation (energy resolution and coincidence resolution time (CRT)) was evaluated during simultaneous operation of the MRI scanner. We used clinically motivated imaging sequences as well as synthetic gradient stress test sequences. Without activity of the MRI scanner, we measured for trigger scheme 1 (first photon trigger) an energy resolution of 11.4% and a CRT of 213 ps for a narrow energy (NE) window using five 22Na point-like sources. When applying the synthetic gradient sequences, we found worst-case relative degradations of the energy resolution by 5.1% and of the CRT by 33.9%. After identifying the origin of the degradations and implementing a fix to the read-out hardware, the same evaluation revealed no degradation of the PET performance anymore even when the most demanding gradient stress tests were applied. The PET performance of the insert was initially evaluated using the point sources, a high-activity phantom and hot-rod phantoms in order to assess the spatial resolution. Trigger schemes 2-4 delivered an energy resolution of 11.4% as well and CRTs of 279 ps, 333 ps and 557 ps for the NE window, respectively. An isocenter sensitivity of 0.41% using the NE window and 0.71% with a wide energy window was measured. Using a hot-rod phantom, a spatial resolution in the order of 2 mm was demonstrated and the

Mechanically stable, hierarchically porous Cu3(btc)2 (HKUST-1) monoliths via direct conversion of copper(II) hydroxide-based monoliths.

Science.gov (United States)

Moitra, Nirmalya; Fukumoto, Shotaro; Reboul, Julien; Sumida, Kenji; Zhu, Yang; Nakanishi, Kazuki; Furukawa, Shuhei; Kitagawa, Susumu; Kanamori, Kazuyoshi

2015-02-28

The synthesis of highly crystalline macro-meso-microporous monolithic Cu3(btc)2 (HKUST-1; btc(3-) = benzene-1,3,5-tricarboxylate) is demonstrated by direct conversion of Cu(OH)2-based monoliths while preserving the characteristic macroporous structure. The high mechanical strength of the monoliths is promising for possible applications to continuous flow reactors.

Crystallization of poly(ethyleneterephthalate) modified with codiols

NARCIS (Netherlands)

Bouma, K.; Regelink, Marc; Gaymans, R.J.

2001-01-01

The nucleation of poly(ethylene terephthalate) (PET) by codiols and olefinic segments was studied. The codiols 1,5-pentanediol, 1,8-octanediol, 2,5-hexanediol, and 1,3-dihydroxymethyl benzene were copolymerized into PET in a concentration range of 0-10 mol %. The melting (Tm), crystallization (Tc),

Evaluation of static physics performance of the jPET-D4 by Monte Carlo simulations

Energy Technology Data Exchange (ETDEWEB)

Hasegawa, Tomoyuki [Allied Health Sciences, Kitasato University, Kitasato 1-15-1, Sagamihara, Kanagawa, 228-8555 (Japan); Yoshida, Eiji [Molecular Imaging Centre, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba, 263-8555 (Japan); Kobayashi, Ayako [Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa, Tokyo, 116-8551 (Japan); Shibuya, Kengo [Molecular Imaging Centre, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba, 263-8555 (Japan); Nishikido, Fumihiko [Molecular Imaging Centre, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba, 263-8555 (Japan); Kobayashi, Tetsuya [Graduate School of Science and Technology, Chiba University, 1-33 Yayoi, Inage, Chiba, 263-8522 (Japan); Suga, Mikio [Graduate School of Science and Technology, Chiba University, 1-33 Yayoi, Inage, Chiba, 263-8522 (Japan); Yamaya, Taiga [Molecular Imaging Centre, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba, 263-8555 (Japan); Kitamura, Keishi [Shimadzu Corporation, 1 Nishinokyo-kuwabara-cho, Nakagyo-ku, Kyoto, 604-8511 (Japan); Maruyama, Koichi [Allied Health Sciences, Kitasato University, Kitasato 1-15-1, Sagamihara, Kanagawa, 228-8555 (Japan); Murayama, Hideo [Molecular Imaging Centre, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba, 263-8555 (Japan)

2007-01-07

The jPET-D4 is the first PET scanner to introduce a unique four-layer depth-of-interaction (DOI) detector scheme in order to achieve high sensitivity and uniform high spatial resolution. This paper compares measurement and Monte Carlo simulation results of the static physics performance of this prototype research PET scanner. Measurement results include single and coincidence energy spectra, point and line source sensitivities, axial sensitivity profile (slice profile) and scatter fraction. We use GATE (Geant4 application for tomographic emission) as a Monte Carlo radiation transport model. Experimental results are reproduced well by the simulation model with reasonable assumptions on characteristic responses of the DOI detectors. In a previous study, the jPET-D4 was shown to provide a uniform spatial resolution as good as 3 mm (FHWM). In the present study, we demonstrate that a high sensitivity, 11.3 {+-} 0.5%, is provided at the FOV centre. However, about three-fourths of this sensitivity is related to multiple-crystal events, for which some misidentification of the crystal cannot be avoided. Therefore, it is crucial to develop a more efficient way to identify the crystal of interaction and to reduce misidentification in order to make use of these high performance values simultaneously. We expect that effective sensitivity can be improved by replacing the GSO crystals with more absorptive crystals such as BGO and LSO. The results we describe here are essential to take full advantage of the next generation PET systems that have DOI recognition capability.

Synthesis of Porous Carbon Monoliths Using Hard Templates.

Science.gov (United States)

Klepel, Olaf; Danneberg, Nina; Dräger, Matti; Erlitz, Marcel; Taubert, Michael

2016-03-21

The preparation of porous carbon monoliths with a defined shape via template-assisted routes is reported. Monoliths made from porous concrete and zeolite were each used as the template. The porous concrete-derived carbon monoliths exhibited high gravimetric specific surface areas up to 2000 m²·g -1 . The pore system comprised macro-, meso-, and micropores. These pores were hierarchically arranged. The pore system was created by the complex interplay of the actions of both the template and the activating agent as well. On the other hand, zeolite-made template shapes allowed for the preparation of microporous carbon monoliths with a high volumetric specific surface area. This feature could be beneficial if carbon monoliths must be integrated into technical systems under space-limited conditions.

A depth-of-interaction PET detector using mutual gain-equalized silicon photomultiplier

International Nuclear Information System (INIS)

Xi, W.; Weisenberger, A.G.; Dong, H.; Kross, Brian; Lee, S.; McKisson, J.; Zorn, Carl

2012-01-01

We developed a prototype high resolution, high efficiency depth-encoding detector for PET applications based on dual-ended readout of LYSO array with two silicon photomultipliers (SiPMs). Flood images, energy resolution, and depth-of-interaction (DOI) resolution were measured for a LYSO array - 0.7 mm in crystal pitch and 10 mm in thickness - with four unpolished parallel sides. Flood images were obtained such that individual crystal element in the array is resolved. The energy resolution of the entire array was measured to be 33%, while individual crystal pixel elements utilizing the signal from both sides ranged from 23.3% to 27%. By applying a mutual-gain equalization method, a DOI resolution of 2 mm for the crystal array was obtained in the experiments while simulations indicate ∼1 mm DOI resolution could possibly be achieved. The experimental DOI resolution can be further improved by obtaining revised detector supporting electronics with better energy resolutions. This study provides a detailed detector calibration and DOI response characterization of the dual-ended readout SiPM-based PET detectors, which will be important in the design and calibration of a PET scanner in the future.

Study of continuous DOI positioning for solid-state PET detectors

International Nuclear Information System (INIS)

Lee, Chae Hun

2007-02-01

PET is a nuclear imaging technique that measures the spatial and temporal distribution of compounds labeled with a positron emitting radionuclide introduced into a subject to be determined non-invasively. Spatial resolution degradation occurs at the edge of Field Of View (FOV) due to parallax error. To improve spatial resolution at the edge of FOV, Depth-Of-Interaction (DOI) PET has been investigated and there are several methods for DOI positioning. Among DOI positioning methods, sharing scintillation light output is the cost-effective and accurate method while solid-state photosensors such as Avalanche Photodiodes have been well developed. Avalanche photodiodes have internal gain by impact ionizations in high electric field. High gain and low noise are good characteristics for use in PET. In this thesis, DOI-PET detector using two APD with LSO scintillation crystal was designed and evaluated, and parameter to affect DOI positioning was investigated. Energy resolution of the designed detector was 12 % in 662 keV photopeak. Comparing photopeak channels of two APD output, DOI position was measured. DOI positioning error was ±2.5 mm. DOI resolution in current DOI-PET systems is still ∼ cm. Minimum 4 step positions can be obtained with 2 cm long LSO crystal in this result

Characterization of highly multiplexed monolithic PET / gamma camera detector modules

DEFF Research Database (Denmark)

Pierce, L. A.; Pedemonte, Stefano; Dewitt, Sharon

2018-01-01

tube with 8 × 8 position-outputs and one channel that is the sum of the other 64. The 65-channel signal was multiplexed in a resistive circuit, with 65:5 or 65:7 multiplexing. A 0.9 mm beam of 511 keV photons was scanned across the face of the crystal in a 1.52 mm grid pattern in order to characterize...... and scatter-rejection capabilities of the detector were analyzed. We found that using a 7-channel multiplexing scheme (65:7 compression ratio) with 1.67 mm depth bins had the best performance with a beam-contour of 1.2 mm FWHM (from the 0.9 mm beam) near the center of the crystal and 1.9 mm FWHM near the edge...... the detector response. New methods are developed to reject scattered events and perform depthestimation to characterize the detector response of the calibration data. Photon interaction position estimation of the testing data was performed using a Gaussian Maximum Likelihood estimator and the resolution...

Phase Field Modeling Using PetIGA

KAUST Repository

Vignal, Philippe; Collier, Nathan; Calo, Victor M.

2013-01-01

, and having a highly efficient and parallel framework to solve them is necessary. In this work, a brief review on phase field models is given, followed by a short analysis of the Phase Field Crystal Model solved with Isogeometric Analysis us- ing PetIGA. We

Evaluation of New Inorganic Scintillators for Application in a Prototype Small Animal PET Scanner

CERN Document Server

Kuntner, C

2003-01-01

In the study of new pharmaceuticals as well as brain and genetic research, Positron Emission Tomography (PET) is a useful method. It has also recently entered the clinical domain in cardiology and particularly in oncology. Small animals such as mice, are often used to validate sophisticated models of human disease. High spatial resolution PET instrumentation is therefore necessary due to the reduced dimensions of the organs. Inorganic scintillators are employed in most of the diagnostic imaging devices. The ultimate performance of the PET scanner is tightly bound to the scintillation properties of the crystals. In the last years there has been an effort to develop new scintillating materials characterized by high light output, high detection efficiency and fast decay time. The most studied systems are mainly Ce3+-doped crystals such as LSO:Ce, YAP:Ce, LuAP:Ce, and recently also mixed Lux(RE3+)1-xAlO3:Ce crystals. These crystals are very attractive for medical application because of their high density (with th...

Nano-Doped Monolithic Materials for Molecular Separation

Directory of Open Access Journals (Sweden)

Caleb Acquah

2017-01-01

Full Text Available Monoliths are continuous adsorbents that can easily be synthesised to possess tuneable meso-/macropores, convective fluid transport, and a plethora of chemistries for ligand immobilisation. They are grouped into three main classes: organic, inorganic, and hybrid, based on their chemical composition. These classes may also be differentiated by their unique morphological and physicochemical properties which are significantly relevant to their specific separation applications. The potential applications of monoliths for molecular separation have created the need to enhance their characteristic properties including mechanical strength, electrical conductivity, and chemical and thermal stability. An effective approach towards monolith enhancement has been the doping and/or hybridization with miniaturized molecular species of desirable functionalities and characteristics. Nanoparticles are usually preferred as dopants due to their high solid phase dispersion features which are associated with improved intermolecular adsorptive interactions. Examples of such nanomaterials include, but are not limited to, carbon-based, silica-based, gold-based, and alumina nanoparticles. The incorporation of these nanoparticles into monoliths via in situ polymerisation and/or post-modification enhances surface adsorption for activation and ligand immobilisation. Herein, insights into the performance enhancement of monoliths as chromatographic supports by nanoparticles doping are presented. In addition, the potential and characteristics of less common nanoparticle materials such as hydroxyapatite, ceria, hafnia, and germania are discussed. The advantages and challenges of nanoparticle doping of monoliths are also discussed.

Simulation study comparing the helmet-chin PET with a cylindrical PET of the same number of detectors

Science.gov (United States)

Ahmed, Abdella M.; Tashima, Hideaki; Yoshida, Eiji; Nishikido, Fumihiko; Yamaya, Taiga

2017-06-01

There is a growing interest in developing brain PET scanners with high sensitivity and high spatial resolution for early diagnosis of neurodegenerative diseases and studies of brain functions. Sensitivity of the PET scanner can be improved by increasing the solid angle. However, conventional PET scanners are designed based on a cylindrical geometry, which may not be the most efficient design for brain imaging in terms of the balance between sensitivity and cost. We proposed a dedicated brain PET scanner based on a hemispheric shape detector and a chin detector (referred to as the helmet-chin PET), which is designed to maximize the solid angle by increasing the number of lines-of-response in the hemisphere. The parallax error, which PET scanners with a large solid angle tend to have, can be suppressed by the use of depth-of-interaction detectors. In this study, we carry out a realistic evaluation of the helmet-chin PET using Monte Carlo simulation based on the 4-layer GSO detector which consists of a 16  ×  16  ×  4 array of crystals with dimensions of 2.8  ×  2.8  ×  7.5 mm3. The purpose of this simulation is to show the gain in imaging performance of the helmet-chin PET compared with the cylindrical PET using the same number of detectors in each configuration. The sensitivity of the helmet-chin PET evaluated with a cylindrical phantom has a significant increase, especially at the top of the (field-of-view) FOV. The peak-NECR of the helmet-chin PET is 1.4 times higher compared to the cylindrical PET. The helmet-chin PET provides relatively low noise images throughout the FOV compared to the cylindrical PET which exhibits enhanced noise at the peripheral regions. The results show the helmet-chin PET can significantly improve the sensitivity and reduce the noise in the reconstructed images.

Translucency and Strength of High-Translucency Monolithic Zirconium-Oxide Materials

Science.gov (United States)

2016-05-12

Capt Todd D. Church APPROVED: Translucency and Strength of High-Translucency Monolithic Zirconium -Oxide Materials C~t) Kraig/[ Vandewalle Date...copyrighted material in the thesis/dissertation manuscript entitled: "Translucency arid Strength of High-Translucency Monolithic Zirconium -Oxide...Translucency Monolithic Zirconium -Oxide Materials Abstract Dental materials manufacturers have developed more translucent monolithic zirconium oxide

High-Resolution PET Detector. Final report

International Nuclear Information System (INIS)

Karp, Joel

2014-01-01

The objective of this project was to develop an understanding of the limits of performance for a high resolution PET detector using an approach based on continuous scintillation crystals rather than pixelated crystals. The overall goal was to design a high-resolution detector, which requires both high spatial resolution and high sensitivity for 511 keV gammas. Continuous scintillation detectors (Anger cameras) have been used extensively for both single-photon and PET scanners, however, these instruments were based on NaI(Tl) scintillators using relatively large, individual photo-multipliers. In this project we investigated the potential of this type of detector technology to achieve higher spatial resolution through the use of improved scintillator materials and photo-sensors, and modification of the detector surface to optimize the light response function.We achieved an average spatial resolution of 3-mm for a 25-mm thick, LYSO continuous detector using a maximum likelihood position algorithm and shallow slots cut into the entrance surface

Impact of event positioning algorithm on performance of a whole-body PET scanner using one-to-one coupled detectors

Science.gov (United States)

Surti, S.; Karp, J. S.

2018-03-01

The advent of silicon photomultipliers (SiPMs) has introduced the possibility of increased detector performance in commercial whole-body PET scanners. The primary advantage of these photodetectors is the ability to couple a single SiPM channel directly to a single pixel of PET scintillator that is typically 4 mm wide (one-to-one coupled detector design). We performed simulation studies to evaluate the impact of three different event positioning algorithms in such detectors: (i) a weighted energy centroid positioning (Anger logic), (ii) identifying the crystal with maximum energy deposition (1st max crystal), and (iii) identifying the crystal with the second highest energy deposition (2nd max crystal). Detector simulations performed with LSO crystals indicate reduced positioning errors when using the 2nd max crystal positioning algorithm. These studies are performed over a range of crystal cross-sections varying from 1  ×  1 mm2 to 4  ×  4 mm2 as well as crystal thickness of 1 cm to 3 cm. System simulations were performed for a whole-body PET scanner (85 cm ring diameter) with a long axial FOV (70 cm long) and show an improvement in reconstructed spatial resolution for a point source when using the 2nd max crystal positioning algorithm. Finally, we observe a 30-40% gain in contrast recovery coefficient values for 1 and 0.5 cm diameter spheres when using the 2nd max crystal positioning algorithm compared to the 1st max crystal positioning algorithm. These results show that there is an advantage to implementing the 2nd max crystal positioning algorithm in a new generation of PET scanners using one-to-one coupled detector design with lutetium based crystals, including LSO, LYSO or scintillators that have similar density and effective atomic number as LSO.

Preliminary results of a prototype C-shaped PET designed for an in-beam PET system

International Nuclear Information System (INIS)

Kim, Hyun-Il; Chung, Yong Hyun; Lee, Kisung; Kim, Kyeong Min; Kim, Yongkwon; Joung, Jinhun

2016-01-01

Positron emission tomography (PET) can be utilized in particle beam therapy to verify the dose distribution of the target volume as well as the accuracy of the treatment. We present an in-beam PET scanner that can be integrated into a particle beam therapy system. The proposed PET scanner consisted of 14 detector modules arranged in a C-shape to avoid blockage of the particle beam line by the detector modules. Each detector module was composed of a 9×9 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals optically coupled to four 29-mm-diameter PMTs using the photomultiplier-quadrant-sharing (PQS) technique. In this study, a Geant4 Application for Tomographic Emission (GATE) simulation study was conducted to design a C-shaped PET scanner and then experimental evaluation of the proposed design was performed. The spatial resolution and sensitivity were measured according to NEMA NU2-2007 standards and were 6.1 mm and 5.61 cps/kBq, respectively, which is in good agreement with our simulation, with an error rate of 12.0%. Taken together, our results demonstrate the feasibility of the proposed C-shaped in-beam PET system, which we expect will be useful for measuring dose distribution in particle therapy.

Selective oxidation of cyclohexene through gold functionalized silica monolith microreactors

Science.gov (United States)

Alotaibi, Mohammed T.; Taylor, Martin J.; Liu, Dan; Beaumont, Simon K.; Kyriakou, Georgios

2016-04-01

Two simple, reproducible methods of preparing evenly distributed Au nanoparticle containing mesoporous silica monoliths are investigated. These Au nanoparticle containing monoliths are subsequently investigated as flow reactors for the selective oxidation of cyclohexene. In the first strategy, the silica monolith was directly impregnated with Au nanoparticles during the formation of the monolith. The second approach was to pre-functionalize the monolith with thiol groups tethered within the silica mesostructure. These can act as evenly distributed anchors for the Au nanoparticles to be incorporated by flowing a Au nanoparticle solution through the thiol functionalized monolith. Both methods led to successfully achieving even distribution of Au nanoparticles along the length of the monolith as demonstrated by ICP-OES. However, the impregnation method led to strong agglomeration of the Au nanoparticles during subsequent heating steps while the thiol anchoring procedure maintained the nanoparticles in the range of 6.8 ± 1.4 nm. Both Au nanoparticle containing monoliths as well as samples with no Au incorporated were tested for the selective oxidation of cyclohexene under constant flow at 30 °C. The Au free materials were found to be catalytically inactive with Au being the minimum necessary requirement for the reaction to proceed. The impregnated Au-containing monolith was found to be less active than the thiol functionalized Au-containing material, attributable to the low metal surface area of the Au nanoparticles. The reaction on the thiol functionalized Au-containing monolith was found to depend strongly on the type of oxidant used: tert-butyl hydroperoxide (TBHP) was more active than H2O2, likely due to the thiol induced hydrophobicity in the monolith.

Preparation of polyhedral oligomeric silsesquioxane based imprinted monolith.

Science.gov (United States)

Li, Fang; Chen, Xiu-Xiu; Huang, Yan-Ping; Liu, Zhao-Sheng

2015-12-18

Polyhedral oligomeric silsesquioxane (POSS) was successfully applied, for the first time, to prepare imprinted monolithic column with high porosity and good permeability. The imprinted monolithic column was synthesized with a mixture of PSS-(1-Propylmethacrylate)-heptaisobutyl substituted (MA 0702), naproxon (template), 4-vinylpyridine, and ethylene glycol dimethacrylate, in ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4). The influence of synthesis parameters on the retention factor and imprinting effect, including the amount of MA 0702, the ratio of template to monomer, and the ratio of monomer to crosslinker, was investigated. The greatest imprinting factor on the imprinted monolithic column prepared with MA 0702 was 22, about 10 times higher than that prepared in absence of POSS. The comparisons between MIP monoliths synthesized with POSS and without POSS were made in terms of permeability, column efficiency, surface morphology and pore size distribution. In addition, thermodynamic and Van Deemter analysis were used to evaluate the POSS-based MIP monolith. Copyright © 2015 Elsevier B.V. All rights reserved.

Solid state polymerization: its action on thermal and rheological properties of PET/PC reactive blends

Directory of Open Access Journals (Sweden)

Luis C. Mendes

2013-01-01

Full Text Available The solid state polymerization (SSP of PET/PC reactive extrusion blends - with and without cobalt catalyst - at different polymer ratios was studied. Thermal and rheological evaluations were performed. DSC results showed changes in the PET's Tg, Tch, Tm and Xc.. The melt flow rate (MFR decreased for PET and the blends. The intrinsic viscosity increased. The variation in calorimetric and rheological properties might be attributed to the PET's chain extension reactions - esterification and transesterification. These reactions led to an increase in the PET's molar mass, consequently shifting the PET's Tg to lower temperature and PET's crystallization, besides reducing the blend miscibility and flowability.

Protective Skins for Aerogel Monoliths

Science.gov (United States)

Leventis, Nicholas; Johnston, James C.; Kuczmarski, Maria A.; Meador, Ann B.

2007-01-01

A method of imparting relatively hard protective outer skins to aerogel monoliths has been developed. Even more than aerogel beads, aerogel monoliths are attractive as thermal-insulation materials, but the commercial utilization of aerogel monoliths in thermal-insulation panels has been inhibited by their fragility and the consequent difficulty of handling them. Therefore, there is a need to afford sufficient protection to aerogel monoliths to facilitate handling, without compromising the attractive bulk properties (low density, high porosity, low thermal conductivity, high surface area, and low permittivity) of aerogel materials. The present method was devised to satisfy this need. The essence of the present method is to coat an aerogel monolith with an outer polymeric skin, by painting or spraying. Apparently, the reason spraying and painting were not attempted until now is that it is well known in the aerogel industry that aerogels collapse in contact with liquids. In the present method, one prevents such collapse through the proper choice of coating liquid and process conditions: In particular, one uses a viscous polymer precursor liquid and (a) carefully controls the amount of liquid applied and/or (b) causes the liquid to become cured to the desired hard polymeric layer rapidly enough that there is not sufficient time for the liquid to percolate into the aerogel bulk. The method has been demonstrated by use of isocyanates, which, upon exposure to atmospheric moisture, become cured to polyurethane/polyurea-type coats. The method has also been demonstrated by use of commercial epoxy resins. The method could also be implemented by use of a variety of other resins, including polyimide precursors (for forming high-temperature-resistant protective skins) or perfluorinated monomers (for forming coats that impart hydrophobicity and some increase in strength).

Validation of a simultaneous PET/MR system model for PET simulation using GATE

International Nuclear Information System (INIS)

Monnier, Florian; Fayad, Hadi; Bert, Julien; Schmidt, Holger; Visvikis, Dimitris

2015-01-01

Simultaneous PET/MR acquisition shows promise in a range of applications. Simulation using GATE is an essential tool that allows obtaining the ground truth for such acquisitions and therefore helping in the development and the validation of innovative processing methods such as PET image reconstruction, attenuation correction and motion correction. The purpose of this work is to validate the GATE simulation of the Siemens Biograph mMR PET/MR system. A model of the Siemens Biograph mMR was developed. This model includes the geometry and spatial positioning of the crystals inside the scanner and the characteristics of the detection process. The accuracy of the model was tested by comparing, on a real physical phantom study, GATE simulated results to reconstructed PET images using measured results obtained from a Siemens Biograph mMR system. The same parameters such as the acquisition time and phantom position inside the scanner were fixed for our simulations. List-mode outputs were recovered in both cases and reconstructed using the OPL-EM algorithm. Several parameters were used to compare the two reconstructed images such as profile comparison, signal-to-noise ratio and activity contrast analysis. Finally patient acquired MR images were segmented and used for the simulation of corresponding PET images. The simulated and acquired sets of reconstructed phantom images showed close emission values in regions of interest with relative differences lower than 5%. The scatter fraction was within a <3% agreement. Close matching of profiles and contrast indices were obtained between simulated and corresponding acquired PET images. Our results indicate that the GATE developed Biograph mMR model is accurate in comparison to the real scanner performance and can be used for evaluating innovative processing methods for applications in clinical PET/MR protocols.

Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

Science.gov (United States)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

2015-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

Advanced Gasification Mercury/Trace Metal Control with Monolith Traps

Energy Technology Data Exchange (ETDEWEB)

Musich, Mark; Swanson, Michael; Dunham, Grant; Stanislowski, Joshua

2010-10-05

Two Corning monoliths and a non-carbon-based material have been identified as potential additives for mercury capture in syngas at temperatures above 400°F and pressure of 600 psig. A new Corning monolith formulation, GR-F1-2189, described as an active sample appeared to be the best monolith tested to date. The Corning SR Liquid monolith concept continues to be a strong candidate for mercury capture. Both monolith types allowed mercury reduction to below 5-μg/m{sup 3} (~5 ppb), a current U.S. Department of Energy (DOE) goal for trace metal control. Preparation methods for formulating the SR Liquid monolith impacted the ability of the monolith to capture mercury. The Energy & Environmental Research Center (EERC)-prepared Noncarbon Sorbents 1 and 2 appeared to offer potential for sustained and significant reduction of mercury concentration in the simulated fuel gas. The Noncarbon Sorbent 1 allowed sustained mercury reduction to below 5-μg/m{sup 3} (~5 ppb). The non-carbon-based sorbent appeared to offer the potential for regeneration, that is, desorption of mercury by temperature swing (using nitrogen and steam at temperatures above where adsorption takes place). A Corning cordierite monolith treated with a Group IB metal offered limited potential as a mercury sorbent. However, a Corning carbon-based monolith containing prereduced metallic species similar to those found on the noncarbon sorbents did not exhibit significant or sustained mercury reduction. EERC sorbents prepared with Group IB and IIB selenide appeared to have some promise for mercury capture. Unfortunately, these sorbents also released Se, as was evidenced by the measurement of H2Se in the effluent gas. All sorbents tested with arsine or hydrogen selenide, including Corning monoliths and the Group IB and IIB metal-based materials, showed an ability to capture arsine or hydrogen selenide at 400°F and 600 psig. Based on current testing, the noncarbon metal-based sorbents appear to be the most

ADVANCED GASIFICATION MERCURY/TRACE METAL CONTROL WITH MONOLITH TRAPS

Energy Technology Data Exchange (ETDEWEB)

Mark A. Musich; Michael L. Swanson; Grant E. Dunham; Joshua J. Stanislowski

2010-07-31

Two Corning monoliths and a non-carbon-based material have been identified as potential additives for mercury capture in syngas at temperatures above 400°F and pressure of 600 psig. A new Corning monolith formulation, GR-F1-2189, described as an active sample appeared to be the best monolith tested to date. The Corning SR Liquid monolith concept continues to be a strong candidate for mercury capture. Both monolith types allowed mercury reduction to below 5-μg/m3 (~5 ppb), a current U.S. Department of Energy (DOE) goal for trace metal control. Preparation methods for formulating the SR Liquid monolith impacted the ability of the monolith to capture mercury. The Energy & Environmental Research Center (EERC)-prepared Noncarbon Sorbents 1 and 2 appeared to offer potential for sustained and significant reduction of mercury concentration in the simulated fuel gas. The Noncarbon Sorbent 1 allowed sustained mercury reduction to below 5-μg/m3 (~5 ppb). The non-carbon-based sorbent appeared to offer the potential for regeneration, that is, desorption of mercury by temperature swing (using nitrogen and steam at temperatures above where adsorption takes place). A Corning cordierite monolith treated with a Group IB metal offered limited potential as a mercury sorbent. However, a Corning carbon-based monolith containing prereduced metallic species similar to those found on the noncarbon sorbents did not exhibit significant or sustained mercury reduction. EERC sorbents prepared with Group IB and IIB selenide appeared to have some promise for mercury capture. Unfortunately, these sorbents also released Se, as was evidenced by the measurement of H2Se in the effluent gas. All sorbents tested with arsine or hydrogen selenide, including Corning monoliths and the Group IB and IIB metal-based materials, showed an ability to capture arsine or hydrogen selenide at 400°F and 600 psig. Based on current testing, the noncarbon metal-based sorbents appear to be the most effective arsine

Design and development of 1 mm resolution PET detectors with position-sensitive PMTs

CERN Document Server

Shao, Y; Chatziioannou, A F

2002-01-01

We report our investigation of a positron emission tomography (PET) detector with 1 m spatial resolution. The prototype detector consists of a 9x9 array of 1x1x10 mm sup 3 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to Hamamatsu R5900-M64 or R5900-C12 position sensitive PMT by either optical fibers or an optical fiber bundle. With a 511 eV gamma source, the intrinsic spatial resolution of this detector was measured to be 0.92 mm. All crystals were well resolved in the flood source histogram. The measured energy and coincidence timing resolutions were around 26% and 4 ns, respectively, demonstrating that sufficient light can be extracted from these small crystals for PET applications.

Detector normalization and scatter correction for the jPET-D4: A 4-layer depth-of-interaction PET scanner

Energy Technology Data Exchange (ETDEWEB)

Kitamura, Keishi [Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan)]. E-mail: kitam@shimadzu.co.jp; Ishikawa, Akihiro [Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Mizuta, Tetsuro [Shimadzu Corporation, 1 Nishinokyo-Kuwabaracho, Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Yamaya, Taiga [National Institute of Radiological Sciences, 9-1 Anagawa-4, Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Yoshida, Eiji [National Institute of Radiological Sciences, 9-1 Anagawa-4, Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Murayama, Hideo [National Institute of Radiological Sciences, 9-1 Anagawa-4, Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)

2007-02-01

The jPET-D4 is a brain positron emission tomography (PET) scanner composed of 4-layer depth-of-interaction (DOI) detectors with a large number of GSO crystals, which achieves both high spatial resolution and high scanner sensitivity. Since the sensitivity of each crystal element is highly dependent on DOI layer depth and incidental {gamma} ray energy, it is difficult to estimate normalization factors and scatter components with high statistical accuracy. In this work, we implemented a hybrid scatter correction method combined with component-based normalization, which estimates scatter components with a dual energy acquisition using a convolution subtraction-method for an estimation of trues from an upper energy window. In order to reduce statistical noise in sinograms, the implemented scheme uses the DOI compression (DOIC) method, that combines deep pairs of DOI layers into the nearest shallow pairs of DOI layers with natural detector samplings. Since the compressed data preserve the block detector configuration, as if the data are acquired using 'virtual' detectors with high {gamma}-ray stopping power, these correction methods can be applied directly to DOIC sinograms. The proposed method provides high-quality corrected images with low statistical noise, even for a multi-layer DOI-PET.

Dopamine-imprinted monolithic column for capillary electrochromatography.

Science.gov (United States)

Aşır, Süleyman; Sarı, Duygu; Derazshamshir, Ali; Yılmaz, Fatma; Şarkaya, Koray; Denizli, Adil

2017-11-01

A dopamine-imprinted monolithic column was prepared and used in capillary electrochromatography as stationary phase for the first time. Dopamine was selectively separated from aqueous solution containing the competitor molecule norepinephrine, which is similar in size and shape to the template molecule. Morphology of the dopamine-imprinted column was observed by scanning electron microscopy. The influence of the organic solvent content of mobile phase, applied pressure and pH of the mobile phase on the recognition of dopamine by the imprinted monolithic column has been evaluated, and the imprinting effect in the dopamine-imprinted monolithic polymer was verified. Developed dopamine-imprinted monolithic column resulted in excellent separation of dopamine from structurally related competitor molecule, norepinephrine. Separation was achieved in a short period of 10 min, with the electrophoretic mobility of 5.81 × 10 -5  m 2 V -1 s -1 at pH 5.0 and 500 mbar pressure. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Algebraic 2D PET image reconstruction using depth-of-interaction information

International Nuclear Information System (INIS)

Yamaya, Taiga; Obi, Takashi; Yamaguchi, Masahiro; Kita, Kouichi

2001-01-01

Recently a high-performance PET scanner, which measures depth-of-interaction (DOI) information, is being developed for molecular imaging. DOI measurement of multi-layered thin crystals can improve spatial resolution and scanner sensitivity simultaneously. In this paper, we apply an algebraic image reconstruction method to 2-dimensional (2D) DOI-PET scanners using accurate system modeling, in order to evaluate the effects of using DOI information on PET image quality. Algebraic image reconstruction methods have been successfully used to improve PET image quality, compared with the conventional filtered backprojection method. The proposed method is applied to simulated data for a small 2D DOI-PET scanner. The results show that accurate system modeling improves spatial resolution without noise emphasis, and that DOI information improves uniformity of spatial resolution. (author)

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

NARCIS (Netherlands)

Brunner, S.E.K.; Schaart, D.R.

2017-01-01

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times

Biomimetic small peptide functionalized affinity monoliths for monoclonal antibody purification.

Science.gov (United States)

Wang, Xiangyu; Xia, Donghai; Han, Hai; Peng, Kun; Zhu, Peijie; Crommen, Jacques; Wang, Qiqin; Jiang, Zhengjin

2018-08-09

The rapid development of monoclonal antibodies (mAbs) in therapeutic and diagnostic applications has necessitated the advancement of mAbs purification technologies. In this study, a biomimetic small peptide ligand 3,5-di-tert-butyl-4-hydroxybenzoic acid-Arg-Arg-Gly (DAAG) functionalized monolith was fabricated through a metal ion chelation-based multi-step approach. The resulting monolith showed good chromatographic performance. Compared with the Ni 2+ based IMAC monolith, the DAAG functionalized monolith exhibited not only excellent specificity but also higher dynamic binding capacity (DBC). The 10% DBC and 50% DBC for hIgG reached as high values as 26.0 and 34.6 mg/mL, respectively, at a ligand density of 8.8 μmol/mL, due to the high porosity and accessibility of the monolithic matrix. Moreover, the stability of the DAAG functionalized monolith in successive breakthrough experiments indicates that it has a promising potential for long-term use in mAbs purification. Finally, the DAAG functionalized monolith was successfully applied to the purification of trastuzumab or human immunoglobulin G (hIgG) from biological samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Single-frequency, fully integrated, miniature DPSS laser based on monolithic resonator

Science.gov (United States)

Dudzik, G.; Sotor, J.; Krzempek, K.; Soboń, G.; Abramski, K. M.

2014-02-01

We present a single frequency, stable, narrow linewidth, miniature laser sources operating at 532 nm (or 1064 nm) based on a monolithic resonators. Such resonators utilize birefringent filters formed by YVO4 beam displacer and KTP or YVO4 crystals to force single frequency operation at 532 nm or 1064 nm, respectively. In both configurations Nd:YVO4 gain crystal is used. The resonators dimensions are 1x1x10.5 mm3 and 1x1x8.5 mm3 for green and infrared configurations, respectively. Presented laser devices, with total dimensions of 40x52x120 mm3, are fully equipped with driving electronics, pump diode, optical and mechanical components. The highly integrated (36x15x65 mm3) low noise driving electronics with implemented digital PID controller was designed. It provides pump current and resonator temperature stability of ±30 μA@650 mA and ±0,003ºC, respectively. The laser parameters can be set and monitored via the USB interface by external application. The developed laser construction is universal. Hence, the other wavelengths can be obtained only by replacing the monolithic resonator. The optical output powers in single frequency regime was at the level of 42 mW@532 nm and 0.5 W@1064 nm with the long-term fluctuations of ±0.85 %. The linewidth and the passive frequency stability under the free running conditions were Δν < 100 kHz and 3ṡ10-9@1 s integration time, respectively. The total electrical power supply consumption of laser module was only 4 W. Presented compact, single frequency laser operating at 532 nm and 1064 nm may be used as an excellent source for laser vibrometry, interferometry or seed laser for fiber amplifiers.

An improved multicrystal 2-D BGO detector for PET

International Nuclear Information System (INIS)

Rogers, J.G.; Taylor, A.J.; Rahimi, M.F.; Nutt, R.; Andreaco, M.; Williams, C.W.

1992-01-01

In this paper, the authors evaluate and compare two new 2-D array detectors for PET. Both consist of an 8 x 8 array of small BGO crystals coupled to a 2 x 2 array of photomultiplier tubes. The depth of the crystals is 3 cm in one detector and 2 cm in the other. The 2 cm detector is obviously superior in terms of material costs, but is also superior in energy resolution per crystal, and in its ability to clearly identify the crystal containing the primary interaction. The authors present a flexible and robust algorithm for crystal identification in such array detectors. The prospect of obtaining still better spatial resolution from such block detectors, with increased numbers of crystals, is discussed

Monolithic, High-Speed Fiber-Optic Switching Array for Lidar

Science.gov (United States)

Suckow, Will; Roberts, Tony; Switzer, Gregg; Terwilliger, Chelle

2011-01-01

Current fiber switch technologies use mechanical means to redirect light beams, resulting in slow switch time, as well as poor reliability due to moving parts wearing out quickly at high speeds. A non-mechanical ability to switch laser output into one of multiple fibers within a fiber array can provide significant power, weight, and costs savings to an all-fiber system. This invention uses an array of crystals that act as miniature prisms to redirect light as an electric voltage changes the prism s properties. At the heart of the electro-optic fiber-optic switch is an electro- optic crystal patterned with tiny prisms that can deflect the beam from the input fiber into any one of the receiving fibers arranged in a linear array when a voltage is applied across the crystal. Prism boundaries are defined by a net dipole moment in the crystal lattice that has been poled opposite to the surrounding lattice fabricated using patterned, removable microelectrodes. When a voltage is applied across the crystal, the resulting electric field changes the index of refraction within the prism boundaries relative to the surrounding substrate, causing light to deflect slightly according to Snell s Law. There are several materials that can host the necessary monolithic poled pattern (including, but not limited to, SLT, KTP, LiNbO3, and Mg:LiNbO3). Be cause this is a solid-state system without moving parts, it is very fast, and does not wear down easily. This invention is applicable to all fiber networks, as well as industries that use such networks. The unit comes in a compact package, can handle both low and high voltages, and has a high reliability (100,000 hours without maintenance).

Collection of scintillation light from small BGO crystals

International Nuclear Information System (INIS)

Cherry, S.R.; Shao, Y.; Tornai, M.P.; Siegel, S.; Ricci, A.R.; Phelps, M.E.

1995-01-01

The authors propose to develop a high resolution positron emission tomography (PET) detector designed for animal imaging. The detector consists of a 2-D array of small bismuth germanate (BGO) crystals coupled via optical fibers to a multi-channel photomultiplier tube (MC-PMT). Though this approach offers several advantages over the conventional BGO block design, it does require that a sufficient number of scintillation photons be transported from the crystal, down the fiber and into the PMT. In this study the authors use simulations and experimental data to determine how to maximize the signal reaching the PMT. This involves investigating factors such as crystal geometry, crystal surface treatment, the use of reflectors, choice of optical fiber, coupling of crystals to the optical fiber and optical fiber properties. Their results indicate that using 2 x 2 x 10 mm BGO crystals coupled to 30 cm of clad optical fiber, roughly 50 photoelectrons are produced at the PMT photocathode for a 511 keV interaction. This is sufficient to clearly visualize the photopeak and provide adequate timing resolution for PET. Based on these encouraging results, a prototype detector will now be constructed

Aspartic acid incorporated monolithic columns for affinity glycoprotein purification.

Science.gov (United States)

Armutcu, Canan; Bereli, Nilay; Bayram, Engin; Uzun, Lokman; Say, Rıdvan; Denizli, Adil

2014-02-01

Novel aspartic acid incorporated monolithic columns were prepared to efficiently affinity purify immunoglobulin G (IgG) from human plasma. The monolithic columns were synthesised in a stainless steel HPLC column (20 cm × 5 mm id) by in situ bulk polymerisation of N-methacryloyl-L-aspartic acid (MAAsp), a polymerisable derivative of L-aspartic acid, and 2-hydroxyethyl methacrylate (HEMA). Monolithic columns [poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid) (PHEMAsp)] were characterised by swelling studies, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The monolithic columns were used for IgG adsorption/desorption from aqueous solutions and human plasma. The IgG adsorption depended on the buffer type, and the maximum IgG adsorption from aqueous solution in phosphate buffer was 0.085 mg/g at pH 6.0. The monolithic columns allowed for one-step IgG purification with a negligible capacity decrease after ten adsorption-desorption cycles. Copyright © 2013 Elsevier B.V. All rights reserved.

Study and development of a PET device dedicated to cancer monitoring

International Nuclear Information System (INIS)

Vandenbussche, Vincent

2014-01-01

Medical imaging first began at the end of the 19. century with the discover of X-rays by Roentgen. Then, numerous imaging modalities have been developed and are used now for a wide range of cases. Positron Emission Tomography (PET) has a high sensitivity, is functional and quantitative, thus being of high interest in cancer monitoring. Nevertheless, PET is not as much spread in hospitals as magnetic resonance imaging and scanner. In this context, this work aims to prove the feasibility of PET dedicated for cancer monitoring. Thanks to instrumental developments such as light sharing in scintillating crystals, use of Silicon Photomultipliers, and an original geometry, cost is expected to be reduced while having same performances as commercial devices. An extensive study of light sharing within scintillating barrels has been made, through many parameters (crystal length, coating, data analysis...). An intrinsic spatial resolution of 4 mm has been measured over a 75 mm long crystal of LYSO, coated with teflon. From such a configuration, a first image has been reconstructed using two modules in coincidence. A spatial resolution of 5 mm has been measured in the image. Finally, Monte Carlo simulations has been made with experimental data as input, in order to measure the performances of the final PET device. Thanks to NEMA standard protocol, performances has been measured and compared to other systems. A spatial resolution of 4 mm has been reached, for a sensitivity of 2.5 cps/kBq. Quantification problem has been assessed, providing results similar to existing devices. (author) [fr

Fire resistance of prefabricated monolithic slab

Directory of Open Access Journals (Sweden)

Gravit Marina

2017-01-01

Full Text Available A prefabricated monolithic slab (PMS has a number of valuable advantages, they allow to significantly decrease the weight of construction keeping the necessary structural-load capacity, to speed up and cheapen work conduction, to increase the heat isolating properties of an enclosure structure [1]. In order to create a design method of prefabricated monolithic slab fire-resistance, it's necessary to perform a series of PMS testing, one of which is being described in this article. Subjected to the test is a fragment of prefabricated monolithic slab with polystyrene concrete inserts along the beams with bent metal profile 250 mm thick, with a 2.7 m span loaded with evenly spread load equal to 600 kg/m2. After 3 hour testing for fire-resistance [2] no signs of construction ultimate behavior were detected.

Extended Leach Testing of Simulated LAW Cast Stone Monoliths

Energy Technology Data Exchange (ETDEWEB)

Serne, R. Jeffrey [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westsik, Joseph H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Williams, Benjamin D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jung, H. B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Guohui [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-07-09

This report describes the results from long-term laboratory leach tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate the release of key constituents from monoliths of Cast Stone prepared with four simulated low-activity waste (LAW) liquid waste streams. Specific objectives of the Cast Stone long-term leach tests described in this report focused on four activities: 1. Extending the leaching times for selected ongoing EPA-1315 tests on monoliths made with LAW simulants beyond the conventional 63-day time period up to 609 days reported herein (with some tests continuing that will be documented later) in an effort to evaluate long-term leaching properties of Cast Stone to support future performance assessment activities. 2. Starting new EPA-1315 leach tests on archived Cast Stone monoliths made with four LAW simulants using two leachants (deionized water [DIW] and simulated Hanford Integrated Disposal Facility (IDF) Site vadose zone pore water [VZP]). 3. Evaluating the impacts of varying the iodide loading (starting iodide concentrations) in one LAW simulant (7.8 M Na Hanford Tank Waste Operations Simulator (HTWOS) Average) by manufacturing new Cast Stone monoliths and repeating the EPA-1315 leach tests using DIW and the VZP leachants. 4. Evaluating the impacts of using a non-pertechnetate form of Tc that is present in some Hanford tanks. In this activity one LAW simulant (7.8 M Na HTWOS Average) was spiked with a Tc(I)-tricarbonyl gluconate species and then solidified into Cast Stone monoliths. Cured monoliths were leached using the EPA-1315 leach protocol with DIW and VZP. The leach results for the Tc-Gluconate Cast Stone monoliths were compared to Cast Stone monoliths pertechnetate.

Validation of GEANT3 simulation studies with a dual-head PMT ClearPET TM prototype

CERN Document Server

Ziemons, K; Streun, M; Pietrzyk, U

2004-01-01

The ClearPET TM project is proposed by working groups of the Crystal Clear Collaboration (CCC) to develop a 2/sup nd/ generation high performance small animal positron emission tomograph (PET). High sensitivity and high spatial resolution is foreseen for the ClearPET TM camera by using a phoswich arrangement combining mixed lutetium yttrium aluminum perovskite (LuYAP:Ce) and lutetium oxyorthosilicate (LSO) scintillating crystals. Design optimizations for the first photomultiplier tube (PMT) based ClearPET camera are done with a Monte-Carlo simulation package implemented on GEANT3 (CERN, Geneva, Switzerland). A dual-head prototype has been built to test the frontend electronics and was used to validate the implementation of the GEANT3 simulation tool. Multiple simulations were performed following the experimental protocols to measure the intrinsic resolution and the sensitivity profile in axial and radial direction. Including a mean energy resolution of about 27.0% the simulated intrinsic resolution is about (...

Development of high-throughput analysis system using highly-functional organic polymer monoliths

International Nuclear Information System (INIS)

Umemura, Tomonari; Kojima, Norihisa; Ueki, Yuji

2008-01-01

The growing demand for high-throughput analysis in the current competitive life sciences and industries has promoted the development of high-speed HPLC techniques and tools. As one of such tools, monolithic columns have attracted increasing attention and interest in the last decade due to the low flow-resistance and excellent mass transfer, allowing for rapid separations and reactions at high flow rates with minimal loss of column efficiency. Monolithic materials are classified into two main groups: silica- and organic polymer-based monoliths, each with their own advantages and disadvantages. Organic polymer monoliths have several distinct advantages in life-science research, including wide pH stability, less irreversible adsorption, facile preparation and modification. Thus, we have so far tried to develop organic polymer monoliths for various chemical operations, such as separation, extraction, preconcentration, and reaction. In the present paper, recent progress in the development of organic polymer monoliths is discussed. Especially, the procedure for the preparation of methacrylate-based monoliths with various functional groups is described, where the influence of different compositional and processing parameters on the monolithic structure is also addressed. Furthermore, the performance of the produced monoliths is demonstrated through the results for (1) rapid separations of alklybenzenes at high flow rates, (2) flow-through enzymatic digestion of cytochrome c on a trypsin-immobilized monolithic column, and (3) separation of the tryptic digest on a reversed-phase monolithic column. The flexibility and versatility of organic polymer monoliths will be beneficial for further enhancing analytical performance, and will open the way for new applications and opportunities both in scientific and industrial research. (author)

Influence of different carbon monolith preparation parameters on pesticide adsorption

Directory of Open Access Journals (Sweden)

Vukčević Marija

2013-01-01

Full Text Available The capacity of carbon monolith for pesticide removal from water, and the mechanism of pesticide interaction with carbon surface were examined. Different carbon monolith samples were obtained by varying the carbonization and activation parameters. In order to examine the role of surface oxygen groups in pesticide adsorption, carbon monolith surface was functionalized by chemical treatment in HNO3, H2O2 and KOH. The surface properties of the obtained samples were investigated by BET surface area, pore size distribution and temperature-programmed desorption. Adsorption of pesticides from aqueous solution onto activated carbon monolith samples was studied by using five pesticides belonging to different chemical groups (acetamiprid, dimethoate, nicosulfuron, carbofuran and atrazine. Presented results show that higher temperature of carbonization and the amount of activating agent allow obtaining microporous carbon monolith with higher amount of surface functional groups. Adsorption properties of the activated carbon monolith were more readily affected by the amount of the surface functional groups than by specific surface area. Results obtained by carbon monolith functionalisation showed that π-π interactions were the main force for adsorption of pesticides with aromatic structure, while acidic groups play an important role in adsorption of pesticides with no aromatic ring in the chemical structure.

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure.

Science.gov (United States)

Sun, Xiaoxia; Uyama, Hiroshi

2013-10-04

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields.

A SiPM-based isotropic-3D PET detector X'tal cube with a three-dimensional array of 1 mm{sup 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Yamaya, Taiga; Mitsuhashi, Takayuki; Inadama, Naoko; Nishikido, Fumihiko; Yoshida, Eiji; Murayama, Hideo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Matsumoto, Takahiro; Kawai, Hideyuki; Suga, Mikio [Chiba University, 1-33 Yayoicho, Inage-ku, Chiba 263-8522 (Japan); Watanabe, Mitsuo, E-mail: taiga@nirs.go.jp [Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu 434-8601 (Japan)

2011-11-07

We are developing a novel, general purpose isotropic-3D PET detector X'tal cube which has high spatial resolution in all three dimensions. The research challenge for this detector is implementing effective detection of scintillation photons by covering six faces of a segmented crystal block with silicon photomultipliers (SiPMs). In this paper, we developed the second prototype of the X'tal cube for a proof-of-concept. We aimed at realizing an ultimate detector with 1.0 mm{sup 3} cubic crystals, in contrast to our previous development using 3.0 mm{sup 3} cubic crystals. The crystal block was composed of a 16 x 16 x 16 array of lutetium gadolinium oxyorthosilicate (LGSO) crystals 0.993 x 0.993 x 0.993 mm{sup 3} in size. The crystals were optically glued together without inserting any reflector inside and 96 multi-pixel photon counters (MPPCs, S10931-50P, i.e. six faces each with a 4 x 4 array of MPPCs), each having a sensitive area of 3.0 x 3.0 mm{sup 2}, were optically coupled to the surfaces of the crystal block. Almost all 4096 crystals were identified through Anger-type calculation due to the finely adjusted reflector sheets inserted between the crystal block and light guides. The reflector sheets, which formed a belt of 0.5 mm width, were placed to cover half of the crystals of the second rows from the edges in order to improve identification performance of the crystals near the edges. Energy resolution of 12.7% was obtained at 511 keV with almost uniform light output for all crystal segments thanks to the effective detection of the scintillation photons.

Depth of interaction calibration for PET detectors with dual-ended readout by PSAPDs

International Nuclear Information System (INIS)

Yang Yongfeng; Qi Jinyi; Wu Yibao; St James, Sara; Cherry, Simon R; Farrell, Richard; Dokhale, Purushottam A; Shah, Kanai S

2009-01-01

Many laboratories develop depth-encoding detectors to improve the trade-off between spatial resolution and sensitivity in positron emission tomography (PET) scanners. One challenge in implementing these detectors is the need to calibrate the depth of interaction (DOI) response for the large numbers of detector elements in a scanner. In this work, we evaluate two different methods, a linear detector calibration and a linear crystal calibration, for determining DOI calibration parameters. Both methods can use measurements from any source distribution and location, or even the intrinsic lutetium oxyorthosilicate (LSO) background activity, and are therefore well suited for use in a depth-encoding PET scanner. The methods were evaluated by measuring detector and crystal DOI responses for all eight detectors in a prototype depth-encoding PET scanner. The detectors utilize dual-ended readout of LSO scintillator arrays with position-sensitive avalanche photodiodes (PSAPDs). The LSO arrays have 7 x 7 elements, with a crystal size of 0.92 x 0.92 x 20 mm 3 and pitch of 1.0 mm. The arrays are read out by two 8 x 8 mm 2 area PSAPDs placed at opposite ends of the arrays. DOI is measured by the ratio of the amplitude of the total energy signals measured by the two PSAPDs. Small variations were observed in the DOI responses of different crystals within an array as well as DOI responses for different arrays. A slightly nonlinear dependence of the DOI ratio on depth was observed and the nonlinearity was larger for the corner and edge crystals. The DOI calibration parameters were obtained from the DOI responses measured in a singles mode. The average error between the calibrated DOI and the known DOI was 0.8 mm if a linear detector DOI calibration was used and 0.5 mm if a linear crystal DOI calibration was used. A line source phantom and a hot rod phantom were scanned on the prototype PET scanner. DOI measurement significantly improved the image spatial resolution no matter which DOI

Development of an MR-compatible DOI-PET detector module

Energy Technology Data Exchange (ETDEWEB)

Wei, Qingyang [Department of Electrical Engineering, Tsinghua University, Beijing (China); Key Laboratory of Particle and Radiation Imaging, Ministry of Education (Tsinghua University), Beijing (China); Wang, Shi; Xu, Tianpeng; Gao, Yunpeng; Liu, Yaqiang; Ma, Tianyu [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle and Radiation Imaging, Ministry of Education (Tsinghua University), Beijing (China)

2015-05-18

Silicon Photomultiplier (SiPM) is a promising sensor for MR-compatible PET systems. In this paper, we developed a compact 2-layer DOI-PET detector. The top layer is a 15×15 LYSO array, and the crystal size is 2x2x7mm{sup 3}. The bottom layer is a 16×16 array with the same size crystals. There is half-crystal offset between two layers in both transverse directions. The detector is coupled to an 8×8 SiPM array (MicroFB-30035-SMT, Sensl). Sixty-four channels of SiPMs are read out by an ASIC chip with in-chip multiplexing resistor networks in the form of two position and one energy analog signals, and are then converted to wave-form digital signals with 80 MHz 12-bit ADC chips. The energy is calculated by averaging the 3 points around the peak of the pulse. Flood images with two 22Na point sources irradiated on the top and at the bottom of the detector module were acquired. The results show that the detector module achieves good crystal identification capability in both layers with an average energy resolution of 17.1% at 511 keV.

Development of an MR-compatible DOI-PET detector module

International Nuclear Information System (INIS)

Wei, Qingyang; Wang, Shi; Xu, Tianpeng; Gao, Yunpeng; Liu, Yaqiang; Ma, Tianyu

2015-01-01

Silicon Photomultiplier (SiPM) is a promising sensor for MR-compatible PET systems. In this paper, we developed a compact 2-layer DOI-PET detector. The top layer is a 15×15 LYSO array, and the crystal size is 2x2x7mm 3 . The bottom layer is a 16×16 array with the same size crystals. There is half-crystal offset between two layers in both transverse directions. The detector is coupled to an 8×8 SiPM array (MicroFB-30035-SMT, Sensl). Sixty-four channels of SiPMs are read out by an ASIC chip with in-chip multiplexing resistor networks in the form of two position and one energy analog signals, and are then converted to wave-form digital signals with 80 MHz 12-bit ADC chips. The energy is calculated by averaging the 3 points around the peak of the pulse. Flood images with two 22Na point sources irradiated on the top and at the bottom of the detector module were acquired. The results show that the detector module achieves good crystal identification capability in both layers with an average energy resolution of 17.1% at 511 keV.

Crystallization-induced plasticity of Cu-Zr containing bulk amorphous alloys

International Nuclear Information System (INIS)

Lee, Seok-Woo; Huh, Moo-Young; Fleury, Eric; Lee, Jae-Chul

2006-01-01

This study examined the parameter governing the plasticity observed in various Cu-Zr containing monolithic amorphous alloys. All the alloys were fully amorphous in their as-cast condition but exhibited different plastic strains. Microscopic observations of the quasi-statically compressed alloys showed abundant nanocrystallites in the amorphous matrices in the alloys that exhibited pronounced plasticity. On the other hand, insignificant changes in the microstructure were observed in the alloy that did not show plasticity. The mechanism for the formation of these deformation-induced nanocrystallites was examined from the viewpoints of thermodynamics and kinetics. The role of the deformation-induced nanocrystallites on the plasticity of the amorphous alloy was examined using high-resolution transmission electron microscopy. The results demonstrate that compressive loading facilitates nanocrystallization in monolithic Cu-Zr containing amorphous alloys, resulting in plasticity. The parameter governing the plasticity in these monolithic Cu-Zr containing amorphous alloys lies in the activation energy for the overall crystallization process

Acoustic of monolithic dome structures

Directory of Open Access Journals (Sweden)

Mostafa Refat Ismail

2018-03-01

The interior of monolithic domes have perfect, concave shapes to ensure that sound travels through the dome and perfectly collected at different vocal points. These dome structures are utilized for domestic use because the scale allows the focal points to be positioned across daily life activities, thereby affecting the sonic comfort of the internal space. This study examines the various acoustic treatments and parametric configurations of monolithic dome sizes. A geometric relationship of acoustic treatment and dome radius is established to provide architects guidelines on the correct selection of absorption needed to maintain the acoustic comfort of these special spaces.

Media Presentation Synchronisation for Non-monolithic Rendering Architectures

NARCIS (Netherlands)

I. Vaishnavi (Ishan); D.C.A. Bulterman (Dick); P.S. Cesar Garcia (Pablo Santiago); B. Gao (Bo)

2007-01-01

htmlabstractNon-monolithic renderers are physically distributed media playback engines. Non-monolithic renderers may use a number of different underlying network connection types to transmit media items belonging to a presentation. There is therefore a need for a media based and inter-network- type

Edge chipping and flexural resistance of monolithic ceramics☆

Science.gov (United States)

Zhang, Yu; Lee, James J.-W.; Srikanth, Ramanathan; Lawn, Brian R.

2014-01-01

Objective Test the hypothesis that monolithic ceramics can be developed with combined esthetics and superior fracture resistance to circumvent processing and performance drawbacks of traditional all-ceramic crowns and fixed-dental-prostheses consisting of a hard and strong core with an esthetic porcelain veneer. Specifically, to demonstrate that monolithic prostheses can be produced with a much reduced susceptibility to fracture. Methods Protocols were applied for quantifying resistance to chipping as well as resistance to flexural failure in two classes of dental ceramic, microstructurally-modified zirconias and lithium disilicate glass–ceramics. A sharp indenter was used to induce chips near the edges of flat-layer specimens, and the results compared with predictions from a critical load equation. The critical loads required to produce cementation surface failure in monolithic specimens bonded to dentin were computed from established flexural strength relations and the predictions validated with experimental data. Results Monolithic zirconias have superior chipping and flexural fracture resistance relative to their veneered counterparts. While they have superior esthetics, glass–ceramics exhibit lower strength but higher chip fracture resistance relative to porcelain-veneered zirconias. Significance The study suggests a promising future for new and improved monolithic ceramic restorations, with combined durability and acceptable esthetics. PMID:24139756

Noise and physical limits to maximum resolution of PET images

Energy Technology Data Exchange (ETDEWEB)

Herraiz, J.L.; Espana, S. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Vicente, E.; Vaquero, J.J.; Desco, M. [Unidad de Medicina y Cirugia Experimental, Hospital GU ' Gregorio Maranon' , E-28007 Madrid (Spain); Udias, J.M. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)], E-mail: jose@nuc2.fis.ucm.es

2007-10-01

In this work we show that there is a limit for the maximum resolution achievable with a high resolution PET scanner, as well as for the best signal-to-noise ratio, which are ultimately related to the physical effects involved in the emission and detection of the radiation and thus they cannot be overcome with any particular reconstruction method. These effects prevent the spatial high frequency components of the imaged structures to be recorded by the scanner. Therefore, the information encoded in these high frequencies cannot be recovered by any reconstruction technique. Within this framework, we have determined the maximum resolution achievable for a given acquisition as a function of data statistics and scanner parameters, like the size of the crystals or the inter-crystal scatter. In particular, the noise level in the data as a limitation factor to yield high-resolution images in tomographs with small crystal sizes is outlined. These results have implications regarding how to decide the optimal number of voxels of the reconstructed image or how to design better PET scanners.

Noise and physical limits to maximum resolution of PET images

International Nuclear Information System (INIS)

Herraiz, J.L.; Espana, S.; Vicente, E.; Vaquero, J.J.; Desco, M.; Udias, J.M.

2007-01-01

In this work we show that there is a limit for the maximum resolution achievable with a high resolution PET scanner, as well as for the best signal-to-noise ratio, which are ultimately related to the physical effects involved in the emission and detection of the radiation and thus they cannot be overcome with any particular reconstruction method. These effects prevent the spatial high frequency components of the imaged structures to be recorded by the scanner. Therefore, the information encoded in these high frequencies cannot be recovered by any reconstruction technique. Within this framework, we have determined the maximum resolution achievable for a given acquisition as a function of data statistics and scanner parameters, like the size of the crystals or the inter-crystal scatter. In particular, the noise level in the data as a limitation factor to yield high-resolution images in tomographs with small crystal sizes is outlined. These results have implications regarding how to decide the optimal number of voxels of the reconstructed image or how to design better PET scanners

Monte Carlo simulation of a four-layer DOI detector with relative offset in animal PET

International Nuclear Information System (INIS)

Chung, Yong Hyun; Hwang, Ji Yeon; Baek, Cheol-Ha; Lee, Seung-Jae; Ito, Mikiko; Lee, Jae Sung; Hong, Seong Jong

2011-01-01

We have built a four-layer detector to obtain depth of interaction (DOI) information in which all four layers have a relative offset of half a crystal pitch with each other. The main characteristics of the detector, especially the energy and spatial resolutions, strongly depend on the crystal surface treatments. As a part of the development of an animal PET, we have investigated the effect of crystal surface treatment on detector performances using Monte Carlo simulations in order to optimize the surface conditions of crystals composing a four-layer detector. The proposed detector consists of four LYSO layers with crystal dimensions of 1.5x1.5x7.0 and 1.5x1.5x5.0 mm 3 . A simulation tool (DETECT2000) was used and validated against the experimental results; flood images were acquired by a prototype module. Flood images were simulated by varying the surface treatment of the crystals. The optimal surface conditions of the four-layer crystals were derived for a small animal PET with a view towards achieving high sensitivity, as well as high and uniform radial resolution.

Creating deep soil core monoliths: Beyond the solum

Science.gov (United States)

Soil monoliths serve as useful teaching aids in the study of the Earth’s critical zone where rock, soil, water, air, and organisms interact. Typical monolith preparation has so far been confined to the 1 to 2-m depth of the solum. Critical ecosystem services provided by soils include materials from ...

New scintillating crystals for PET scanners

CERN Document Server

Lecoq, P

2002-01-01

Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for a new generation of medical imaging devices with increased resolution and sensitivity. The first important requirement for a scintillator to be used in medical imaging devices is the stopping power for the given energy range of X and gamma rays to be considered, and more precisely the conversion efficiency. A high light yield is also mandatory to improve the energy resolution, which is essentially limited by the photostatistics and the electronic noise at these energies. A short scintillation decay time allows to reduce the dead time and therefore to increase the limiting counting rate. When all these requirements are fulfilled the sensitivity and image contrast are increased for a given patient dose, or the dose can be reduced. Examples of new materials under development by the Crystal Clear Collabor...

Evaluation of PET performance and MR compatibility of a preclinical PET/MR insert with digital silicon photomultiplier technology

Energy Technology Data Exchange (ETDEWEB)

Hallen, Patrick; Schug, David; Wehner, Jakob [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany); Weissler, Bjorn [Department of Chemical Application Research, Philips Research (Germany); Gebhardt, Pierre [Division of Imaging Sciences and Biomedical Engineering, King’s College London (United Kingdom); Goldschmidt, Benjamin [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany); Salomon, Andre [Department of Oncology Solutions, Philips Research (Germany); Duppenbecker, Peter [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany); Kiessling, Fabian [Institute for Experimental Molecular Imaging, RWTH Aachen University (Germany); Schultz, Volkmar [Department of Physics of Molecular Imaging Systems, RWTH Aachen University (Germany)

2015-05-18

In this work we present detailed characterizations of our preclinical high resolution PET/MR insert based on the Hyperion-IID platform. The PET/MR insert consists of a ring of 10 singles detection modules, each comprising 2x3 scintillation detector stacks. Each detector stack features a 30x30 pixelated LYSO crystal array with a height of 12 mm and a pitch of 1 mm, coupled via a slit 2 mm light guide to a digital SiPM tile. The PET performance is stable under a wide range of operating points. The spatial resolution is below 1Ä,mm and the CRT reaches 260 or 450 ps depending on trigger settings. The energy resolution is 12.6% FWHM. The characterization of the MR compatibility showed no relevant degradation in PET performance during MRI operation. On the MRI side, we observe a degradation in B0 homogeneity from a VRMS of 0.03 ppm to 0.08 ppm with active shimming, while observing only minor degradations in the B0 field. The noise floor is slightly increased by 2-15% without any observable dependence on the activity. The Z gradients induces an observable eddy current inside the PET inserts which can lead to ghosting artifacts for EPI sequences. However, we don't observe any visible image degradation for widely used anatomical imaging sequences such as gradient echo and turbo spin echo sequences. To prove the viability of our PET/MR insert for in vivo small animal studies, we successfully performed a longitudinal mouse study with subcutaneously injected tumor model cells. The simultaneously acquired PET/MR images provide a high level of anatomical information and soft tissue contrast in the MR layer together with a high resolution image of the FDG tracer distribution in the PET layer.

FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

International Nuclear Information System (INIS)

Jantzen, C

2006-01-01

Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO 2 and steam, and nitrate/nitrite components, if any, to N 2 . The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO 4 , I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the 2 durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form

Plant oil-based shape memory polymer using acrylic monolith

Directory of Open Access Journals (Sweden)

T. Tsujimoto

2015-09-01

Full Text Available This article deals with the synthesis of a plant oil-based material using acrylic monolith. An acrylic monolith bearing oxirane groups was prepared via simple technique that involved the dissolution of poly(glycidyl methacrylate-comethyl methacrylate (PGMA in ethanolic – aqueous solution by heating and subsequent cooling. The PGMA monolith had topologically porous structure, which was attributed to the phase separation of the polymer solution. The PGMA monolith was impregnated by epoxidized soybean oil (ESO containing thermally-latent catalyst, and the subsequent curing produced a crosslinked material with relatively good transparency. The Young’s modulus and the tensile strength of polyESO/PGMA increased compared with the ESO homopolymer. The strain at break of polyESO/PGMA was larger than that of the ESO homopolymer and crosslinked PGMA. Furthermore, polyESO/PGMA exhibited good shape memory-recovery behavior.

Feasibility of a novel design of high resolution parallax-free Compton enhanced PET scanner dedicated to brain research

CERN Document Server

Braem, André; Chesi, Enrico Guido; Correia, J G; Garibaldi, F; Joram, C; Mathot, S; Nappi, E; Ribeiro da Silva, M; Schoenahl, F; Séguinot, Jacques; Weilhammer, P; Zaidi, H

2004-01-01

A novel concept for a positron emission tomography (PET) camera module is proposed, which provides full 3D reconstruction with high resolution over the total detector volume, free of parallax errors. The key components are a matrix of long scintillator crystals and hybrid photon detectors (HPDs) with matched segmentation and integrated readout electronics. The HPDs read out the two ends of the scintillator package. Both excellent spatial (x, y, z) and energy resolution are obtained. The concept allows enhancing the detection efficiency by reconstructing a significant fraction of events which underwent Compton scattering in the crystals. The proof of concept will first be demonstrated with yttrium orthoaluminate perovskite (YAP):Ce crystals, but the final design will rely on other scintillators more adequate for PET applications (e.g. LSO:Ce or LaBr /sub 3/:Ce). A promising application of the proposed camera module, which is currently under development, is a high resolution 3D brain PET camera with an axial fi...

Data quality objectives summary report for the 105-N monolith off-gas issue

International Nuclear Information System (INIS)

Pisarcik, D.J.

1997-01-01

The 105-N Basin hardware waste with radiation exposure rates high enough to make above-water handling and packaging impractical has been designated high exposure rate hardware (HERH) waste. This material, consisting primarily of irradiated reactor components, is packaged underwater for subsequent disposal as a grout-encapsulated solid monolith. The third HERH waste package that was created (Monolith No. 3) was not immediately removed from the basin because of administrative delays. During a routine facility walkdown, Monolith No. 3 was observed to be emitting bubbles. Mass spectroscopic analysis of a gas sample from Monolith No. 3 indicated that the gas was 85.2% hydrogen along with a trace of fission gases (stable isotopes of xenon). Gamma energy analysis of a gas sample from Monolith No. 3 also identified trace quantities of 85 Kr. The monolith off-gas Data Quality Objective (DQO) process concluded the following: Monolith No. 3 and similar monoliths can be safely transported following installation of spacers between the lids of the L3-181 transport cask to vent the hydrogen gas; The 85 Kr does not challenge personnel or environmental safety; Fumaroles in the surface of gassing monoliths renders them incompatible with Hanford Site Solid Waste Acceptance Criteria requirements unless placed in a qualified high integrity container overpack; and Gassing monoliths do meet Environmental Restoration Disposal Facility Waste Acceptance Criteria requirements. This DQO Summary Report is both an account of the Monolith Off-Gas DQO Process and a means of documenting the concurrence of each of the stakeholder organizations

Next generation PET data acquisition architectures

Science.gov (United States)

Jones, W. F.; Reed, J. H.; Everman, J. L.; Young, J. W.; Seese, R. D.

1997-06-01

New architectures for higher performance data acquisition in PET are proposed. Improvements are demanded primarily by three areas of advancing PET state of the art. First, larger detector arrays such as the Hammersmith ECAT/sup (R/) EXACT HR/sup ++/ exceed the addressing capacity of 32 bit coincidence event words. Second, better scintillators (LSO) make depth-of interaction (DOI) and time-of-flight (TOF) operation more practical. Third, fully optimized single photon attenuation correction requires higher rates of data collection. New technologies which enable the proposed third generation Real Time Sorter (RTS III) include: (1) 80 Mbyte/sec Fibre Channel RAID disk systems, (2) PowerPC on both VMEbus and PCI Local bus, and (3) quadruple interleaved DRAM controller designs. Data acquisition flexibility is enhanced through a wider 64 bit coincidence event word. PET methodology support includes DOI (6 bits), TOF (6 bits), multiple energy windows (6 bits), 512/spl times/512 sinogram indexes (18 bits), and 256 crystal rings (16 bits). Throughput of 10 M events/sec is expected for list-mode data collection as well as both on-line and replay histogramming. Fully efficient list-mode storage for each PET application is provided by real-time bit packing of only the active event word bits. Real-time circuits provide DOI rebinning.

Next generation PET data acquisition architectures

International Nuclear Information System (INIS)

Jones, W.F.; Reed, J.H.; Everman, J.L.

1996-01-01

New architectures for higher performance data acquisition in PET are proposed. Improvements are demanded primarily by three areas of advancing PET state of the art. First, larger detector arrays such as the Hammersmith ECAT reg-sign EXACT HR ++ exceed the addressing capacity of 32 bit coincidence event words. Second, better scintillators (LSO) make depth-of-interaction (DOI) and time-of-flight (TOF) operation more practical. Third, fully optimized single photon attenuation correction requires higher rates of data collection. New technologies which enable the proposed third generation Real Time Sorter (RTS III) include: (1) 80 M byte/sec Fibre Channel RAID disk systems, (2) PowerPC on both VMEbus and PCI Local bus, and (3) quadruple interleaved DRAM controller designs. Data acquisition flexibility is enhanced through a wider 64 bit coincidence event word. PET methodology support includes DOI (6 bits), TOF (6 bits), multiple energy windows (6 bits), 512 x 512 sinogram indexes (18 bits), and 256 crystal rings (16 bits). Throughput of 10 M events/sec is expected for list-mode data collection as well as both on-line and replay histogramming. Fully efficient list-mode storage for each PET application is provided by real-time bit packing of only the active event word bits. Real-time circuits provide DOI rebinning

AX-PET A novel PET detector concept with full 3D reconstruction

CERN Document Server

Braem, A; Séguinot, J; Dissertori, G; Djambazov, L; Lustermann, W; Nessi-Tedaldi, F; Pauss, F; Schinzel, D; Solevi, P; Lacasta, C; Oliver, J F; Rafecas, M; De Leo, R; Nappi, E; Vilardi, I; Chesi, E; Cochran, E; Honscheid, K; Kagan, H; Rudge, A; Smith, S; Weilhammer, P; Johnson, I; Renker, D; Clinthorne, N; Huh, S; Bolle, E; Stapnes, S; Meddi, F

2009-01-01

We describe the concept and first experimental tests of a novel 3D axial Positron Emission Tomography (PET) geometry. It allows for a new way of measuring the interaction point in the detector with very high precision. It is based on a matrix of long Lutetium-Yttrium OxyorthoSilicate (LYSO) crystals oriented in the axial direction, each coupled to one Geiger Mode Avalanche Photodiode (G-APD) array. To derive the axial coordinate, Wave Length Shifter (WLS) strips are mounted orthogonally and interleaved between the crystals. The light from the WLS strips is read by custom-made G-APDs. The weighted mean of the signals in the WLS strips has proven to give very precise axial resolution. The achievable resolution along the three axes is mainly driven by the dimensions of the LYSO crystals and WLS strips. This concept is inherently free of parallax errors. Furthermore, it will allow identification of Compton interactions in the detector and for reconstruction of a fraction of them, which is expected to enhance imag...

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure

OpenAIRE

Sun, Xiaoxia; Uyama, Hiroshi

2013-01-01

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructu...

Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders

NARCIS (Netherlands)

De Kanter, J.L.C.G.

2006-01-01

Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based

In situ prepared PET nanocomposites: Effect of organically modified montmorillonite and fumed silica nanoparticles on PET physical properties and thermal degradation kinetics

International Nuclear Information System (INIS)

Vassiliou, A.A.; Chrissafis, K.; Bikiaris, D.N.

2010-01-01

In the present study a series of PET nanocomposites were prepared by in situ polymerization using different amounts of organically modified montmorillonite (OMMT) with a triphenylphosphine compound and fumed silica nanoparticles (SiO 2 ). As verified by TEM micrographs, the dispersion of both nanoparticles into the PET matrix was homogeneous while montmorillonite was dispersed in the exfoliated form. The intrinsic viscosities of the prepared nanocomposites were affected by the addition of the nanoparticles and in both cases a slight increase was observed. Tensile strength was also increased by increasing nanoparticles content while both types of nanoparticles act as nucleating agents, enhancing the crystallization rates of PET. From the thermogravimetric curves it was concluded that PET and the samples with different nanoparticles presented good thermostability, since no remarkable mass loss occurred up to 320 o C ( 2 2 wt.% nanocomposites was almost identical (222.1 kJ/mol). However, PET/OMMT 2 wt.% nanocomposites exhibited a higher activation energy (228.3 kJ/mol), indicating that OMMT incurred a stabilizing effect upon the decomposition of the matrix. The form of the conversion function for all the studied samples obtained by fitting was the mechanism of n th -order auto-catalysis.

Development of double chain phosphatidylcholine functionalized polymeric monoliths for immobilized artificial membrane chromatography.

Science.gov (United States)

Wang, Qiqin; Peng, Kun; Chen, Weijia; Cao, Zhen; Zhu, Peijie; Zhao, Yumei; Wang, Yuqiang; Zhou, Haibo; Jiang, Zhengjin

2017-01-06

This study described a simple synthetic methodology for preparing biomembrane mimicking monolithic column. The suggested approach not only simplifies the preparation procedure but also improves the stability of double chain phosphatidylcholine (PC) functionalized monolithic column. The physicochemical properties of the optimized monolithic column were characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and nano-LC. Satisfactory column permeability, efficiency, stability and reproducibility were obtained on this double chain PC functionalized monolithic column. It is worth noting that the resulting polymeric monolith exhibits great potential as a useful alternative of commercial immobilized artificial membrane (IAM) columns for in vitro predication of drug-membrane interactions. Furthermore, the comparative study of both double chain and single chain PC functionalized monoliths indicates that the presence or absence of glycerol backbone and the number of acyl chains are not decisive for the predictive ability of IAM monoliths on drug-membrane interactions. This novel PC functionalized monolithic column also exhibited good selectivity for a protein mixture and a set of pharmaceutical compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

Initial performance evaluation of a preclinical PET scanner available as a clip-on assembly in a sequential PET/MRI system.

Science.gov (United States)

Vrigneaud, Jean-Marc; McGrath, John; Courteau, Alan; Pegg, Rosie; Sanchez-Pastor Gomis, Alberto; Camacho, Angela; Martin, Gary; Schramm, Nils; Brunotte, François

2018-05-15

We evaluated the performance characteristics of a prototype preclinical PET scanner available as an easy clippable assembly that can dock to an MRI system. The single ring version of the PET system consists of 8 detectors, each of which comprises a 12 × 12 silicon photomultipliers (SiPMs) array coupled with a dual layer of offset scintillation crystals to measure depth of interaction. The crystal arrays have 29 × 29 (30 × 30 for the outer layer) 4 mm long LYSO crystals (6 mm for the outer layer). The ring diameter is 119.2 mm and the axial field of view is 50.4 mm. The NEMA NU-4-2008 protocol was followed for studying the PET performance. Temperature stability of SiPMs was also investigated. The peak system absolute sensitivity was 4.70% with an energy window of 250-750 keV. The spatial resolution was 1.28/1.88/1.85 mm FWHM (radial/tangential/axial) at a distance of 5 mm from the center. Peak noise equivalent counting rate (NECR) and scatter fraction for mouse phantom were 61.9 kcps at 14.9 MBq and 21.0%, respectively. The uniformity was 6.3% and the spill-over ratios in the images of the water- and air-filled chambers were 0.07 and 0.17, respectively. Recovery coefficients ranged from 0.13 to 0.96. Change in sensitivity as a function of ambient temperature was 0.3%/°C. These first results indicate excellent spatial resolution performance for use with animal studies. Moreover, the clippable assembly can be upgraded to accept a second ring of SiPMs modules, leading to improved sensitivity and axial coverage. © 2018 Institute of Physics and Engineering in Medicine.

Solvent-Induced Crystallization in Poly(Ethylene Terephthalate) during Mass Transport

Science.gov (United States)

Ouyang, Hao

2001-03-01

The solvent transport in poly(ethylene terephthalate) (PET) and related phase transformation were investigated. The data of mass sorption were analyzed according to Harmon¡¦s model for Case I (Fickian), Case II (swelling) and anomalous transport. This transport process in PET is accompanied by the induced crystallization of the original amorphous state. The transformation was studied by wide angle x-ray scattering (WAXS), small angle x-ray scattering (SAXS), Differential Scanning Calorimeter (DSC), density gradient column, and Fourier Transform Infra-Red (FTIR). During this process, the matrix is under a compressive strain that causes different kinetic path of crystallization as compared to that by thermal annealing. This state of strain will assist the development of the solvent-induced crystallization. It also can be explained in terms of the principle of Le Chatelier if the local equilibrium is assumed. The model regarding the crystallization was proposed in terms of the study of long period L, the crystal thickness lc and the thickness of amorphous layer la, obtained from the linear correlation function and interface distribution function.

Synthesis of poly(ethylene furandicarboxylate) polyester using monomers derived from renewable resources: thermal behavior comparison with PET and PEN.

Science.gov (United States)

Papageorgiou, George Z; Tsanaktsis, Vasilios; Bikiaris, Dimitrios N

2014-05-07

Poly(ethylene-2,5-furandicarboxylate) (PEF) is a new alipharomatic polyester that can be prepared from monomers derived from renewable resources like furfural and hydroxymethylfurfural. For this reason it has gained high interest recently. In the present work it was synthesized from the dimethylester of 2,5-furandicarboxylic acid and ethylene glycol by applying the two-stage melt polycondensation method. The thermal behavior of PEF was studied in comparison to its terephthalate and naphthalate homologues poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN), which were also synthesized following the same procedure. The equilibrium melting point of PEF was found to be 265 °C while the heat of fusion for the pure crystalline PEF was estimated to be about 137 J g(-1). The crystallization kinetics was analyzed using various models. PET showed faster crystallization rates than PEN and this in turn showed faster crystallization than PEF, under both isothermal and non-isothermal conditions. The spherulitic morphology of PEF during isothermal crystallization was investigated by polarized light microscopy (PLM). A large nucleation density and a small spherulite size were observed for PEF even at low supercoolings, in contrast to PET or PEN. Thermogravimetric analysis indicated that PEF is thermally stable up to 325 °C and the temperature for the maximum degradation rate was 438 °C. These values were a little lower than those for PET or PEN.

Evaluation of algorithms for photon depth of interaction estimation for the TRIMAGE PET component

Energy Technology Data Exchange (ETDEWEB)

Camarlinghi, Niccolo; Belcari, Nicola [University of Pisa (Italy); Cerello, Piergiorgio [University of Torino (Italy); Sportelli, Giancarlo [University of Pisa (Italy); Pennazio, Francesco [University of Torino (Italy); Zaccario, Emanuele; Del Guerra, Alberto [University of Pisa (Italy)

2015-05-18

The TRIMAGE consortium aims to develop a multimodal PET/MR/EEG brain scanner dedicated to the early diagnosis of schizophrenia and other mental health disorders. The PET component features a full ring made of 18 detectors, each one consisting of twelve 8x8 Silicon PhotoMultipliers (SiPMs) tiles coupled to two segmented LYSO crystal matrices with staggered layers. In each module, the crystals belonging to the bottom layer are coupled one to one to the SiPMs, while each crystal of the top layer is coupled to four crystals of the bottom layer. This configuration allows to increase the crystal thickness while reducing the depth of interaction uncertainty, as photons interacting in different layers are expected to produce different light patterns on the SiPMs. The PET scanner will implement the pixel/layer identification on a front-end FPGA. This will allow increasing the effective bandwidth, setting at the same time restrictions on the complexity of the algorithms to be implemented. In this work two algorithms whose implementation is feasible directly on an FPGA are presented and evaluated. The first algorithm implements a method based on adaptive thresholding, while the other uses a linear Support Vector Machine (SVM) trained to distinguish the light pattern coming from two different layers. The validation of the algorithm performance is carried out by using simulated data generated with the GAMOS Monte Carlo. The obtained results show that the achieved accuracy in layer and pixel identification is above the 90% for both the proposed approaches.

Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

Science.gov (United States)

Wang, Daojing [Daly City, CA; Yang, Peidong [Kensington, CA; Kim, Woong [Seoul, KR; Fan, Rong [Pasadena, CA

2011-09-20

Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

Decomposition of monolithic web application to microservices

OpenAIRE

Zaymus, Mikulas

2017-01-01

Solteq Oyj has an internal Wellbeing project for massage reservations. The task of this thesis was to transform the monolithic architecture of this application to microservices. The thesis starts with a detailed comparison between microservices and monolithic application. It points out the benefits and disadvantages microservice architecture can bring to the project. Next, it describes the theory and possible strategies that can be used in the process of decomposition of an existing monoli...

Simulation study of a depth-encoding positron emission tomography detector inserting horizontal-striped glass between crystal layers

Science.gov (United States)

Kim, Kyu Bom; Choi, Yong; Kang, Jihoon

2017-10-01

This study introduces a depth-encoding positron emission tomography (PET) detector inserting a horizontal-striped glass between the pixilated scintillation crystal layers. This design allows light spreading so that scintillation photons can travel only through the X direction and allows alteration in the light distribution so that it can generate a unique pattern diagram of the two-dimensional (2-D) flood histogram that identifies depth position as well as X-Y position of γ-ray interaction. A Monte Carlo simulation was conducted for the assessment of the depth of interaction (DOI)-PET detector. The traced light distribution for each event was converted into the 2-D flood histogram. Light loss caused by inserting the horizontal-striped glass between the crystal layers was estimated. Applicable weighting factors were examined for each DOI-PET detector. No considerable degradation of light loss was observed. The flood histogram, without overlapping of each crystal position, can be generated for the DOI detector based on each crystal block by inserting the horizontal-striped glass with a thickness of >1 mm and the modified resistive charge division networks with applicable weighting factors. This study demonstrated that the proposed DOI-PET detector can extract the three-dimensional γ-ray interaction position without considerable performance degradations of the PET detector from the 2-D flood histogram.

Comparison of single and dual layer detector blocks for pre-clinical MRI–PET

International Nuclear Information System (INIS)

Thompson, Christopher; Stortz, Greg; Goertzen, Andrew; Berg, Eric; Retière, Fabrice; Kozlowski, Piotr; Ryner, Lawrence; Sossi, Vesna; Zhang, Xuezhu

2013-01-01

Dual or multi-layer crystal blocks have been proposed to minimise the radial blurring effect in PET scanners with small ring diameters. We measured two potential PET detector blocks' performance in a configuration which would allow 16 blocks in a ring which could be inserted in a small animal 7T MRI scanner. Two crystal sizes, 1.60×1.60 mm 2 and 1.20×1.20 mm 2 , were investigated. Single layer blocks had 10 or 12 mm deep crystals, the dual layer blocks had 4 mm deep crystals on the top layer and 6 mm deep crystals on the bottom layer. The crystals in the dual layer blocks are offset by ½ of the crystal pitch to allow for purely geometric crystal identification. Both were read out with SensL 4×4 SiPM arrays. The software identifies 64 crystals in the single layer and either 85 or 113 crystals in the dual layer array, (either 49 or 64 in the lower layers and 36 or 49 in the upper layers). All the crystals were clearly visible in the crystal identification images and their resolvability indexes (average FWHM/crystal separation) were shown to range from 0.29 for the best single layer block to 0.33 for the densest dual layer block. The best coincidence response FWHM was 0.95 mm for the densest block at the centre of the field. This degraded to 1.83 mm at a simulated radial offset of 16 mm from the centre, while the single layer crystals blurred this result to 3.4 mm. The energy resolution was 16.4±2.2% averaged over the 113 crystals of the densest block

Fracture-resistant monolithic dental crowns.

Science.gov (United States)

Zhang, Yu; Mai, Zhisong; Barani, Amir; Bush, Mark; Lawn, Brian

2016-03-01

To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns. Fracture experiments were conducted on anatomically-correct monolithic crown structures cemented to standard dental composite dies, by axial loading of a hard sphere placed between the cusps. The structures were observed in situ during fracture testing, and critical loads to split the structures were measured. Extended finite element modeling (XFEM), with provision for step-by-step extension of embedded cracks, was employed to simulate full failure evolution. Experimental measurements and XFEM predictions were self-consistent within data scatter. In conjunction with a fracture mechanics equation for critical splitting load, the data were used to predict load-sustaining capacity for crowns on actual dentin substrates and for loading with a sphere of different size. Stages of crack propagation within the crown and support substrate were quantified. Zirconia crowns showed the highest fracture loads, lithium disilicate intermediate, and dental nanocomposite lowest. Dental nanocomposite crowns have comparable fracture resistance to natural enamel. The results confirm that monolithic crowns are able to sustain high bite forces. The analysis indicates what material and geometrical properties are important in optimizing crown performance and longevity. Copyright © 2015 Academy of Dental Materials. All rights reserved.

Characterization of SOI monolithic detector system

Science.gov (United States)

Álvarez-Rengifo, P. L.; Soung Yee, L.; Martin, E.; Cortina, E.; Ferrer, C.

2013-12-01

A monolithic active pixel sensor for charged particle tracking was developed. This research is performed within the framework of an R&D project called TRAPPISTe (Tracking Particles for Physics Instrumentation in SOI Technology) whose aim is to evaluate the feasibility of developing a Monolithic Active Pixel Sensor (MAPS) with Silicon-on-Insulator (SOI) technology. Two chips were fabricated: TRAPPISTe-1 and TRAPPISTe-2. TRAPPISTe-1 was produced at the WINFAB facility at the Université catholique de Louvain (UCL), Belgium, in a 2 μm fully depleted (FD-SOI) CMOS process. TRAPPISTe-2 was fabricated with the LAPIS 0.2 μm FD-SOI CMOS process. The electrical characterization on single transistor test structures and of the electronic readout for the TRAPPISTe series of monolithic pixel detectors was carried out. The behavior of the prototypes’ electronics as a function of the back voltage was studied. Results showed that both readout circuits exhibited sensitivity to the back voltage. Despite this unwanted secondary effect, the responses of TRAPPISTe-2 amplifiers can be improved by a variation in the circuit parameters.

A High Resolution Clinical PET with Breast and Whole Body Transfigurations

Science.gov (United States)

2006-08-01

random (acci- dental ) coincidence events were measured using a second de- layed coincidence window and then subtracted from the sino- grams measured in the...limits the coincidence timing resolution. For a PET camera with bismuth germinate crystals (BGO), like our HOTPET, the relatively wide timing gate is... germinate crystal) and a new synchronization process must also be set up between the delayed trigger and the energy/position signals before being passed

Evaluation of pulmonary nodules and lung cancer with one-inch crystal gamma coincidence positron emission tomography/CT versus dedicated positron emission tomography/CT

International Nuclear Information System (INIS)

Moodie, K.; Lau, E.; Hicks, R. J.; Cherk, M. H.; Turlakow, A.; Skinner, S.; Kelly, M. J.; Kalff, V.

2009-01-01

Full text: Dedicated positron emission tomography (PET)/CT scanners using BGO and related detectors (d-PET) have become standard imaging instruments in many malignancies. Hybrid gamma camera systems using Nal detectors in coincidence mode (g-PET) have been compared to d-PET but reported usefulness has been variable when gamma cameras with half-inch to three-fourth-inch thick crystals have been used without CT. Our aim was to compare g-PET with a 1-in.-thick crystal and inbuilt CT for lesion localization and attenuation correction (g-PET/CT) and d-PET/CT in patients presenting with potential and confirmed lung malignancies. One hour after 18F-fluorodeoxyglucose (FDG), patients underwent BGO d-PET/CT from jaw to proximal thigh. This was followed by one to two bed position g-PET/CT 194 + 27 min after FDG. Each study pair was independently analysed with concurrent CT. d-PET/CT was interpreted by a radiologist experienced in both PET and CT, and g-PET/CT by consensus reading of an experienced PET physician and an experienced CT radiologist, A TNM score was assigned and studies were then unblinded and compared. Fifty-seven patients underwent 58 scan pairs over 2 years. Eighty-nine percent concordance was shown between g-PET/CT and d-PET/CT for the assessment of I intrapulmonary lesions, with 100% concordance for intrapulmonary lesions I >10 mm (36 of 36). Eighty-eight per cent (51 of 58) concordance was shown between g-PET/CTand d-PET/CTforTNM staging. Coincidence imaging usingan optimized dual-head 1-in.-thick crystal gamma camera with inbuilt CT compares reasonably well with dedicated PET/CT for evaluation of indeterminate pulmonary lesions and staging of pulmonary malignancies and may be of some] value when d-PET/CT is not readily available.

Agglomerated polymer monoliths with bimetallic nano-particles as flow-through micro-reactors

International Nuclear Information System (INIS)

Floris, P.; Twamley, B.; Nesterenko, P.N.; Paull, B.; Connolly, D.

2012-01-01

Polymer monoliths in capillary format have been prepared as solid supports for the immobilisation of platinum/palladium bimetallic nano-flowers. Optimum surface coverage of nano-flowers was realised by photografting the monoliths with vinyl azlactone followed by amination with ethylenediamine prior to nano-particle immobilisation. Field emission SEM imaging was used as a characterisation tool for evaluating nano-particle coverage, together with BET surface area analysis to probe the effect of nano-particle immobilisation upon monolith morphology. Ion exchange chromatography was also used to confirm the nature of the covalent attachment of nano-flowers on the monolithic surface. In addition, EDX and ICP analyses were used to quantify platinum and palladium on modified polymer monoliths. Finally the catalytic properties of immobilised bimetallic Pd/Pt nano-flowers were evaluated in flow-through mode, exploiting the porous interconnected flow-paths present in the prepared monoliths (pore diameter ∼ 1-2 μm). Specifically, the reduction of Fe (III) to Fe (II) and the oxidation of NADH to NAD+ were selected as model redox reactions. The use of a porous polymer monolith as an immobilisation substrate (rather than aminated micro-spheres) eliminated the need for a centrifugation step after the reaction. (author)

Imaging performance of LabPET APD-based digital PET scanners for pre-clinical research

International Nuclear Information System (INIS)

Bergeron, Mélanie; Cadorette, Jules; Beaudoin, Jean-François; Lecomte, Roger; Tétrault, Marc-André; Leroux, Jean-Daniel; Fontaine, Réjean

2014-01-01

The LabPET is an avalanche photodiode (APD) based digital PET scanner with quasi-individual detector read-out and highly parallel electronic architecture for high-performance in vivo molecular imaging of small animals. The scanner is based on LYSO and LGSO scintillation crystals (2×2×12/14 mm 3 ), assembled side-by-side in phoswich pairs read out by an APD. High spatial resolution is achieved through the individual and independent read-out of an individual APD detector for recording impinging annihilation photons. The LabPET exists in three versions, LabPET4 (3.75 cm axial length), LabPET8 (7.5 cm axial length) and LabPET12 (11.4 cm axial length). This paper focuses on the systematic characterization of the three LabPET versions using two different energy window settings to implement a high-efficiency mode (250–650 keV) and a high-resolution mode (350–650 keV) in the most suitable operating conditions. Prior to measurements, a global timing alignment of the scanners and optimization of the APD operating bias have been carried out. Characteristics such as spatial resolution, absolute sensitivity, count rate performance and image quality have been thoroughly investigated following the NEMA NU 4-2008 protocol. Phantom and small animal images were acquired to assess the scanners' suitability for the most demanding imaging tasks in preclinical biomedical research. The three systems achieve the same radial FBP spatial resolution at 5 mm from the field-of-view center: 1.65/3.40 mm (FWHM/FWTM) for an energy threshold of 250 keV and 1.51/2.97 mm for an energy threshold of 350 keV. The absolute sensitivity for an energy window of 250–650 keV is 1.4%/2.6%/4.3% for LabPET4/8/12, respectively. The best count rate performance peaking at 362 kcps is achieved by the LabPET12 with an energy window of 250–650 keV and a mouse phantom (2.5 cm diameter) at an activity of 2.4 MBq ml −1 . With the same phantom, the scatter fraction for all scanners is about

Imaging and PET - PET/CT imaging

International Nuclear Information System (INIS)

Von Schulthess, G.K.; Hany, Th.F.

2008-01-01

PET/CT has grown because the lack of anatomic landmarks in PET makes 'hardware-fusion' to anatomic cross-sectional data extremely useful. Addition of CT to PET improves specificity, but also sensitivity, and adding PET to CT adds sensitivity and specificity in tumor imaging. The synergistic advantage of adding CT is that the attenuation correction needed for PET data can also be derived from the CT data. This makes PET-CT 25-30% faster than PET alone, leading to higher patient throughput and a more comfortable examination for patients typically lasting 20 minutes or less. FDG-PET-CT appears to provide relevant information in the staging and therapy monitoring of many tumors, such as lung carcinoma, colorectal cancer, lymphoma, gynaecological cancers, melanoma and many others, with the notable exception of prostatic cancer. for this cancer, choline derivatives may possibly become useful radiopharmaceuticals. The published literature on the applications of FDG-PET-CT in oncology is still limited but several designed studies have demonstrated the benefits of PET-CT. (authors)

Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests.

Science.gov (United States)

Demir, Mustafa; Toklu, Türkay; Abuqbeitah, Mohammad; Çetin, Hüseyin; Sezgin, H Sezer; Yeyin, Nami; Sönmezoğlu, Kerim

2018-02-01

The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor. According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated aspects were spatial resolution, sensitivity, scatter fraction, count rate performance, image quality, count loss and random events correction accuracy. The findings of this study demonstrated superior sensitivity (~ 4 folds) of PET scanner in PET/MR compared to PET/CT system. Image quality test exhibited higher contrast in PET/MR (~ 9%) compared with PET/CT. The scatter fraction of PET/MR was 43.4% at noise equivalent count rate (NECR) peak of 218 kcps and the corresponding activity concentration was 17.7 kBq/cc. Whereas the scatter fraction of PET/CT was found as 39.2% at NECR peak of 72 kcps and activity concentration of 24.3 kBq/cc. The percentage error of the random event correction accuracy was 3.4% and 3.1% in PET/MR and PET/CT, respectively. It was concluded that PET/MR system is about 4 times more sensitive than PET/CT, and the contrast of hot lesions in PET/MR was ~ 9% higher than PET/CT. These outcomes also emphasize the possibility to achieve excellent clinical PET images with low administered dose and/or a short acquisition time in PET/MR.

FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

Energy Technology Data Exchange (ETDEWEB)

Jantzen, C

2006-12-22

Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form.

Immobilisation of shredded soft waste in cement monolith

International Nuclear Information System (INIS)

Brown, D.J.; Dalton, M.J.; Smith, D.L.

1983-04-01

A grouting process for the immobilisation of shredded contaminated laboratory waste in a cement monolith is being developed at the Atomic Energy Establishment Winfrith. The objective is to produce a 'monolithic' type package which is acceptable both for sea and land disposal. The work carried out on this project in the period April 1982 - March 1983 is summarised in this report. (author)

Preparation of organic monolithic columns in polytetrafluoroethylene tubes for reversed-phase liquid chromatography

International Nuclear Information System (INIS)

Catalá-Icardo, M.; Torres-Cartas, S.; Meseguer-Lloret, S.; Gómez-Benito, C.; Carrasco-Correa, E.; Simó-Alfonso, E.F.; Ramis-Ramos, G.; Herrero-Martínez, J.M.

2017-01-01

In this work, a method for the preparation and anchoring of polymeric monoliths in a polytetrafluoroethylene (PTFE) tubing as a column housing for microbore HPLC is described. In order to assure a covalent attachment of the monolith to the inner wall of the PTFE tube, a two-step procedure was developed. Two surface etching reagents, a commercial sodium naphthalene solution (Fluoroetch"®), or mixtures of H_2O_2 and H_2SO_4, were tried and compared. Then, the obtained hydroxyl groups on the PTFE surface were modified by methacryloylation. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the successful modification of the tubing wall and the stable anchorage of monolith to the wall, respectively. Special emphasis was also put on the reduction of the unwanted effects of shrinking of monolith during polymerization, by using an external proper mold and by selecting the adequate monomers in order to increase the flexibility of the polymer. Poly(glycidyl methacrylate-co-divinylbenzene) monoliths were in situ synthesized by thermal polymerization within the confines of surface-vinylized PTFE tubes. The modified PTFE tubing tightly held the monolith, and the monolithic column exhibited good pressure resistance up to 20 MPa. The column performance was also evaluated via the isocratic separation of a series of alkylbenzenes in the reversed-phase mode. The optimized monolithic columns gave plate heights ranged between 70 and 80 μm. The resulting monoliths were also satisfactorily applied to the separation of proteins. - Highlights: • Successful surface etching of PTFE inner wall tubing was done. • The modified PTFE support was next methacryloylated with GMA. • Organic polymeric monolith was in situ prepared in the functionalized PTFE tube. • The monolithic columns gave suitable pressure resistance and separation of proteins.

Preparation of organic monolithic columns in polytetrafluoroethylene tubes for reversed-phase liquid chromatography

Energy Technology Data Exchange (ETDEWEB)

Catalá-Icardo, M., E-mail: mocaic@qim.upv.es [Research Institute for Integrated Management of Coastal Areas, Universitat Politècnica de València, Paranimf 1, 46730, Grao de Gandía, Valencia (Spain); Torres-Cartas, S.; Meseguer-Lloret, S.; Gómez-Benito, C. [Research Institute for Integrated Management of Coastal Areas, Universitat Politècnica de València, Paranimf 1, 46730, Grao de Gandía, Valencia (Spain); Carrasco-Correa, E.; Simó-Alfonso, E.F.; Ramis-Ramos, G. [Department of Analytical Chemistry, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Valencia (Spain); Herrero-Martínez, J.M., E-mail: jmherrer@uv.es [Department of Analytical Chemistry, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Valencia (Spain)

2017-04-01

In this work, a method for the preparation and anchoring of polymeric monoliths in a polytetrafluoroethylene (PTFE) tubing as a column housing for microbore HPLC is described. In order to assure a covalent attachment of the monolith to the inner wall of the PTFE tube, a two-step procedure was developed. Two surface etching reagents, a commercial sodium naphthalene solution (Fluoroetch{sup ®}), or mixtures of H{sub 2}O{sub 2} and H{sub 2}SO{sub 4}, were tried and compared. Then, the obtained hydroxyl groups on the PTFE surface were modified by methacryloylation. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the successful modification of the tubing wall and the stable anchorage of monolith to the wall, respectively. Special emphasis was also put on the reduction of the unwanted effects of shrinking of monolith during polymerization, by using an external proper mold and by selecting the adequate monomers in order to increase the flexibility of the polymer. Poly(glycidyl methacrylate-co-divinylbenzene) monoliths were in situ synthesized by thermal polymerization within the confines of surface-vinylized PTFE tubes. The modified PTFE tubing tightly held the monolith, and the monolithic column exhibited good pressure resistance up to 20 MPa. The column performance was also evaluated via the isocratic separation of a series of alkylbenzenes in the reversed-phase mode. The optimized monolithic columns gave plate heights ranged between 70 and 80 μm. The resulting monoliths were also satisfactorily applied to the separation of proteins. - Highlights: • Successful surface etching of PTFE inner wall tubing was done. • The modified PTFE support was next methacryloylated with GMA. • Organic polymeric monolith was in situ prepared in the functionalized PTFE tube. • The monolithic columns gave suitable pressure resistance and separation of proteins.

Increased thermal conductivity monolithic zeolite structures

Science.gov (United States)

Klett, James; Klett, Lynn; Kaufman, Jonathan

2008-11-25

A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

Development and characterization of methacrylate-based hydrazide monoliths for oriented immobilization of antibodies.

Science.gov (United States)

Brne, P; Lim, Y-P; Podgornik, A; Barut, M; Pihlar, B; Strancar, A

2009-03-27

Convective interaction media (CIM; BIA Separations) monoliths are attractive stationary phases for use in affinity chromatography because they enable fast affinity binding, which is a consequence of convectively enhanced mass transport. This work focuses on the development of novel CIM hydrazide (HZ) monoliths for the oriented immobilization of antibodies. Adipic acid dihydrazide (AADH) was covalently bound to CIM epoxy monoliths to gain hydrazide groups on the monolith surface. Two different antibodies were afterwards immobilized to hydrazide functionalized monolithic columns and prepared columns were tested for their selectivity. One column was further tested for the dynamic binding capacity.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

Science.gov (United States)

Brunner, S. E.; Schaart, D. R.

2017-06-01

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ˜10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ˜2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET.

Science.gov (United States)

Brunner, S E; Schaart, D R

2017-06-07

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ∼10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ∼2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm 3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite

Simulation of time curves in small animal PET using GATE

International Nuclear Information System (INIS)

Simon, Luc; Strul, Daniel; Santin, Giovanni; Krieguer, Magalie; Morel, Christian

2004-01-01

The ClearPET project of the Crystal Clear Collaboration (CCC) is building spin-off technology for high resolution small animal Positron Emission Tomography (PET). Monte Carlo simulation is essential for optimizing the specifications of these systems with regards to their most important characteristics, such as spatial resolution, sensitivity, or count rate performance. GATE, the Geant4 Application for Tomographic Emission simulates the passing of time during real acquisitions, allowing to handle dynamic systems such as decaying source distributions or moving detectors. GATE output is analyzed on an event-by-event basis. The time associated with each single event allows to sort coincidences and to model dead-time. This leads to the study of time curves for a prospective small animal PET scanner design. The count rates of true, and random coincidences are discussed together with the corresponding Noise Equivalent Count (NEC) rates as a function of some PET scanner specifications such as detector dead time, or coincidence time window

A Monolithically-Integrated μGC Chemical Sensor System

Directory of Open Access Journals (Sweden)

Davor Copic

2011-06-01

Full Text Available Gas chromatography (GC is used for organic and inorganic gas detection with a range of applications including screening for chemical warfare agents (CWA, breath analysis for diagnostics or law enforcement purposes, and air pollutants/indoor air quality monitoring of homes and commercial buildings. A field-portable, light weight, low power, rapid response, micro-gas chromatography (μGC system is essential for such applications. We describe the design, fabrication and packaging of mGC on monolithically-integrated Si dies, comprised of a preconcentrator (PC, μGC column, detector and coatings for each of these components. An important feature of our system is that the same mechanical micro resonator design is used for the PC and detector. We demonstrate system performance by detecting four different CWA simulants within 2 min. We present theoretical analyses for cost/power comparisons of monolithic versus hybrid μGC systems. We discuss thermal isolation in monolithic systems to improve overall performance. Our monolithically-integrated μGC, relative to its hybrid cousin, will afford equal or slightly lower cost, a footprint that is 1/2 to 1/3 the size and an improved resolution of 4 to 25%.

A novel photocatalytic monolith reactor for multiphase heterogeneous photocatalysis

NARCIS (Netherlands)

Du, P.; Carneiro, J.T.; Moulijn, J.A.; Mul, Guido

2008-01-01

A novel reactor for multi-phase photocatalysis is presented, the so-called internally illuminated monolith reactor (IIMR). In the concept of the IIMR, side light emitting fibers are placed inside the channels of a ceramic monolith, equipped with a TiO2 photocatalyst coated on the wall of each

Development of a SiPM-based PET imaging system for small animals

International Nuclear Information System (INIS)

Lu, Yanye; Yang, Kun; Zhou, Kedi; Zhang, Qiushi; Pang, Bo; Ren, Qiushi

2014-01-01

Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development

Development of a SiPM-based PET imaging system for small animals

Energy Technology Data Exchange (ETDEWEB)

Lu, Yanye [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Yang, Kun, E-mail: yangkun9999@hotmail.com [Department of Control Technology and Instrumentation, College of Quality and Technical Supervision, Hebei University, Baoding, 071000 (China); Zhou, Kedi; Zhang, Qiushi; Pang, Bo [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Ren, Qiushi, E-mail: renqsh@coe.pku.edu.cn [Department of Biomedicine and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

2014-04-11

Advances in small animal positron emission tomography (PET) imaging have been accelerated by many new technologies such as the successful incorporation of silicon photomultiplier (SiPM). In this paper, we have developed a compact, lightweight PET imaging system that is based on SiPM detectors for small animals imaging, which could be integrated into a multi-modality imaging system. This PET imaging system consists of a stationary detector gantry, a motor-controlled animal bed module, electronics modules, and power supply modules. The PET detector, which was designed as a multi-slice circular ring geometry of 27 discrete block detectors, is composed of a cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal and SiPM arrays. The system has a 60 mm transaxial field of view (FOV) and a 26 mm axial FOV. Performance tests (e.g. spatial resolution, energy resolution, and sensitivity) and phantom and animal imaging studies were performed to evaluate the imaging performance of the PET imaging system. The performance tests and animal imaging results demonstrate the feasibility of an animal PET system based on SiPM detectors and indicate that SiPM detectors can be promising photodetectors in animal PET instrumentation development.

Monolithic JFET preamplifier for ionization chamber calorimeter

International Nuclear Information System (INIS)

Radeka, V.; Rescia, S.; Manfredi, P.F.; Speziali, V.

1990-10-01

A monolithic charge sensitive preamplifier using exclusively n-channel diffused JFETs has been designed and is now being fabricated by INTERFET Corp. by means of a dielectrically isolated process which allows preserving as much as possible the technology upon which discrete JFETs are based. A first prototype built by means of junction isolated process has been delivered. The characteristics of monolithically integrated JFETs compare favorably with discrete devices. First results of tests of a preamplifier which uses these devices are reported. 4 refs

ClearPEM: prototype PET device dedicated to breast imaging

CERN Multimedia

Joao Varela

2009-01-01

Clinical trials have begun in Portugal on a new breast imaging system (ClearPEM) using positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

Progress on photonic crystals

CERN Document Server

Lecoq, P; Gundacker, S; Hillemanns, H; Jarron, P; Knapitsch, A; Leclercq, J L; Letartre, X; Meyer, T; Pauwels, K; Powolny, F; Seassal, C

2010-01-01

The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well ...

An overview of monolithic zirconia in dentistry

Directory of Open Access Journals (Sweden)

Özlem Malkondu

2016-07-01

Full Text Available Zirconia restorations have been used successfully for years in dentistry owing to their biocompatibility and good mechanical properties. Because of their lack of translucency, zirconia cores are generally veneered with porcelain, which makes restorations weaker due to failure of the adhesion between the two materials. In recent years, all-ceramic zirconia restorations have been introduced in the dental sector with the intent to solve this problem. Besides the elimination of chipping, the reduced occlusal space requirement seems to be a clear advantage of monolithic zirconia restorations. However, scientific evidence is needed to recommend this relatively new application for clinical use. This mini-review discusses the current scientific literature on monolithic zirconia restorations. The results of in vitro studies suggested that monolithic zirconia may be the best choice for posterior fixed partial dentures in the presence of high occlusal loads and minimal occlusal restoration space. The results should be supported with much more in vitro and particularly in vivo studies to obtain a final conclusion.

Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns

Directory of Open Access Journals (Sweden)

Deborah Pacheco Lameira

2015-01-01

Full Text Available The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP crowns in monolithic (1.5 mm thickness and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n=10: Polished monolithic zirconia crowns (PM; Glazed monolithic zirconia crowns (GM; Bi-layer crowns (BL. Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37°C, and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey’s test (P=.05 indicated that monolithic zirconia crowns presented similar fracture strength (PM=3476.2 N ± 791.7; GM=3561.5 N ± 991.6, which was higher than bilayer crowns (2060.4 N ± 810.6. There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.

Timing Calibration for Time-of-Flight PET Using Positron-Emitting Isotopes and Annihilation Targets

Science.gov (United States)

Li, Xiaoli; Burr, Kent C.; Wang, Gin-Chung; Du, Huini; Gagnon, Daniel

2016-06-01

Adding time-of-flight (TOF) technology has been proven to improve image quality in positron emission tomography (PET). In order for TOF information to significantly reduce the statistical noise in reconstructed PET images, good timing resolution is needed across the scanner field of view (FOV). This work proposes an accurate, robust, and practical crystal-based timing calibration method using 18F - FDG positron-emitting sources together with a spatially separated annihilation target. We calibrated a prototype Toshiba TOF PET scanner using this method and then assessed its timing resolution at different locations in the scanner FOV.

Development and evaluation of an ultra-fast ASIC for future PET scanners using TOF-capable MPPC array detectors

International Nuclear Information System (INIS)

Ambe, T.; Ikeda, H.; Kataoka, J.; Matsuda, H.; Kato, T.

2015-01-01

We developed a front-end ASIC for future PET scanners with Time-Of-Flight (TOF) capability to be coupled with 4×4 Multi-Pixel Photon Counter (MPPC) arrays. The ASIC is designed based on the open-IP project proposed by JAXA and realized in TSMC 0.35 μm CMOS technology. The circuit comprises 16-channel, low impedance current conveyors for effectively acquiring fast MPPC signals. For precise measurement of the coincidence timing of 511-keV gamma rays, the leading-edge method was used to discriminate the signals. We first tested the time response of the ASIC by illuminating each channel of a MPPC array device 3×3 mm 2 in size with a Pico-second Light Pulsar with a light emission peak of 655 nm and pulse duration of 54 ps (FWHM). We obtained 105 ps (FWHM) on average for each channel in time jitter measurements. Moreover, we compensated for the time lag of each channel with inner delay circuits and succeeded in suppressing about a 700-ps lag to only 15 ps. This paper reports TOF measurements using back-to-back 511-keV signals, and suggests that the ASIC can be a promising device for future TOF-PET scanners based on the MPPC array. - Highlights: • We developed a newly designed large-area monolithic MPPC array. • We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. • We fabricated gamma-ray camera consisting of the MPPC array and the submillimeter pixelized LYSO and GGAG scintillators. • In the flood images, each crystal of scintillator matrices was clearly resolved. • Good energy resolutions for 662 keV gamma-rays for each LYSO and GGAG scintillator matrices were obtained

Tannin-based monoliths from emulsion-templating

International Nuclear Information System (INIS)

Szczurek, A.; Martinez de Yuso, A.; Fierro, V.; Pizzi, A.; Celzard, A.

2015-01-01

Highlights: • Efficient preparation procedures are presented for new and “green” tannin-based organic polyHIPEs. • Highest homogeneity and strength are obtained at an oil fraction near the close-packing value. • Structural and mechanical properties abruptly change above such critical value. - Abstract: Highly porous monoliths prepared by emulsion-templating, frequently called polymerised High Internal Phase Emulsions (polyHIPEs) in the literature, were prepared from “green” precursors such as Mimosa bark extract, sunflower oil and ethoxylated castor oil. Various oil fractions, ranging from 43 to 80 vol.%, were used and shown to have a dramatic impact on the resultant porous structure. A critical oil fraction around 70 vol.% was found to exist, close to the theoretical values of 64% and 74% for random and compact sphere packing, respectively, at which the properties of both emulsions and derived porous monoliths changed. Such change of behaviour was observed by many different techniques such as viscosity, electron microscopy, mercury intrusion, and mechanical studies. We show and explain why this critical oil fraction is the one leading to the strongest and most homogeneous porous monoliths

submitter A new method for depth of interaction determination in PET detectors

CERN Document Server

Pizzichemi, M; Niknejad, T; Liu, Z; Lecoq, P; Tavernier, S; Varela, J; Paganoni, M; Auffray, E

2016-01-01

A new method for obtaining depth of interaction (DOI) information in PET detectors is presented in this study, based on sharing and redirection of scintillation light among multiple detectors, together with attenuation of light over the length of the crystals. The aim is to obtain continuous DOI encoding with single side readout, and at the same time without the need for one-toone coupling between scintillators and detectors, allowing the development of a PET scanner with good spatial, energy and timing resolutions while keeping the complexity of the system low. A prototype module has been produced and characterized to test the proposed method, coupling a LYSO scintillator matrix to a commercial SiPMs array. Excellent crystal separation is obtained for all the scintillators in the array, light loss due to depolishing is found to be negligible, energy resolution is shown to be on average 12.7% FWHM. The mean DOI resolution achieved is 4.1mm FWHM on a 15mm long crystal and preliminary coincidence time resolutio...

Design of the PET–MR system for head imaging of the DREAM Project

International Nuclear Information System (INIS)

González, A.J.; Conde, P.; Hernández, L.; Herrero, V.; Moliner, L.; Monzó, J.M.; Orero, A.; Peiró, A.; Rodríguez-Álvarez, M.J.; Ros, A.; Sánchez, F.; Soriano, A.; Vidal, L.F.; Benlloch, J.M.

2013-01-01

In this paper we describe the overall design of a PET–MR system for head imaging within the framework of the DREAM Project as well as the first detector module tests. The PET system design consists of 4 rings of 16 detector modules each and it is expected to be integrated in a head dedicated radio frequency coil of an MR scanner. The PET modules are based on monolithic LYSO crystals coupled by means of optical devices to an array of 256 Silicon Photomultipliers. These types of crystals allow to preserve the scintillation light distribution and, thus, to recover the exact photon impact position with the proper characterization of such a distribution. Every module contains 4 Application Specific Integrated Circuits (ASICs) which return detailed information of several light statistical momenta. The preliminary tests carried out on this design and controlled by means of ASICs have shown promising results towards the suitability of hybrid PET–MR systems

Relevancies of multiple-interaction events and signal-to-noise ratio for Anger-logic based PET detector designs

Science.gov (United States)

Peng, Hao

2015-10-01

A fundamental challenge for PET block detector designs is to deploy finer crystal elements while limiting the number of readout channels. The standard Anger-logic scheme including light sharing (an 8 by 8 crystal array coupled to a 2×2 photodetector array with an optical diffuser, multiplexing ratio: 16:1) has been widely used to address such a challenge. Our work proposes a generalized model to study the impacts of two critical parameters on spatial resolution performance of a PET block detector: multiple interaction events and signal-to-noise ratio (SNR). The study consists of the following three parts: (1) studying light output profile and multiple interactions of 511 keV photons within crystal arrays of different crystal widths (from 4 mm down to 1 mm, constant height: 20 mm); (2) applying the Anger-logic positioning algorithm to investigate positioning/decoding uncertainties (i.e., "block effect") in terms of peak-to-valley ratio (PVR), with light sharing, multiple interactions and photodetector SNR taken into account; and (3) studying the dependency of spatial resolution on SNR in the context of modulation transfer function (MTF). The proposed model can be used to guide the development and evaluation of a standard Anger-logic based PET block detector including: (1) selecting/optimizing the configuration of crystal elements for a given photodetector SNR; and (2) predicting to what extent additional electronic multiplexing may be implemented to further reduce the number of readout channels.

Crystal Clear - New crystals for LHC experiments help to improve PET scanners Exhibition LEPFest 2000

CERN Multimedia

2000-01-01

Better resolution through smaller crystals Better images through higher light yieldHigh efficiency, stability and gain by using avalanche photodiodes and low noise electronics Reduced cost of crystals (1/10) through mass production

Fabrication of mesoporous polymer monolith: a template-free approach.

Science.gov (United States)

Okada, Keisuke; Nandi, Mahasweta; Maruyama, Jun; Oka, Tatsuya; Tsujimoto, Takashi; Kondoh, Katsuyoshi; Uyama, Hiroshi

2011-07-14

Mesoporous polyacrylonitrile (PAN) monolith has been fabricated by a template-free approach using the unique affinity of PAN towards a water/dimethyl sulfoxide (DMSO) mixture. A newly developed Thermally Induced Phase Separation Technique (TIPS) has been used to obtain the polymer monoliths and their microstructures have been controlled by optimizing the concentration and cooling temperature.

Electroacoustic polymer microchip as an alternative to quartz crystal microbalance for biosensor development.

Science.gov (United States)

Gamby, Jean; Lazerges, Mathieu; Girault, Hubert H; Deslouis, Claude; Gabrielli, Claude; Perrot, Hubert; Tribollet, Bernard

2008-12-01

Laser photoablation of poly(ethylene terephthalate) (PET), a flexible dielectric organic polymer, was used to design an acoustic miniaturized DNA biosensor. The microchip device includes a 100-microm-thick PET layer, with two microband electrodes patterned in photoablated microchannels on one side and a depressed photoablated disk decorated by gold sputtered layer on the other side. Upon application of an electric signal between the two electrodes, an electroacoustic resonance phenomenon at approximately 30 MHz was established through the microelectrodes/PET/ gold layer interface. The electroacoustic resonance response was fitted with a series RLC motional arm in parallel with a static Co arm of a Buttlerworth-Van Dyke equivalent circuit: admittance spectra recorded after successive cycles of DNA hybridization on the gold surface showed reproducible changes on R, L, and C parameters. The same hybridizations runs were performed concomitantly on a 27-MHz (9 MHz, third overtone) quartz crystal microbalance in order to validate the PET device developed for bioanalysis applications. The electroacoustic PET device, approximately 100 times smaller than a microbalance quartz crystal, is interesting for the large-scale integration of acoustic sensors in biochips.

Investigation of the optimal detector arrangement for the helmet-chin PET – A simulation study

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Abdella M., E-mail: abdellanur@gmail.com; Tashima, Hideaki; Yoshida, Eiji; Yamaya, Taiga, E-mail: yamaya.taiga@qst.go.jp

2017-06-21

High sensitivity and high spatial resolution dedicated brain PET scanners are in high demand for early diagnosis of neurodegenerative diseases and studies of brain functions. To meet the demand, we have proposed the helmet-chin PET geometry which has a helmet detector and a chin detector. Our first prototype scanner used 54 4-layer depth-of-interaction (DOI) detectors. The helmet detector of the scanner had three detector rings with different radii arranged on a surface of a hemisphere (with a radius of 126.5 mm) and a top cover detector. Therefore, in this study, for our next development, we propose a spherical arrangement, in which the central axis of each detector points toward the center of the hemisphere, and we optimize the size of the detector crystal block to be arranged on the helmet detector. We simulate the spherical arrangement with the optimized crystal block size and compare its imaging performance with the multi-ring arrangement, which has a similar detector arrangement to that of our first prototype. We conduct Monte Carlo simulation to model the scanners having the 4-layer DOI detectors which consist of LYSO crystals. A dead space of 2 mm is assumed on each side of the crystal blocks such as for wrapping. The size of the crystal block is varied from 4×4 mm{sup 2} to 54×54 mm{sup 2} while fixing the thickness of the crystal block to 20 mm. We find that the crystal block sized at 42×42 mm{sup 2} has the highest sensitivity for a hemispherical phantom. The comparison of the two arrangements with the optimized crystal blocks show that, for the same number of crystal blocks, the spherical arrangement has 17% higher sensitivity for the hemispherical phantom than the multi-ring arrangement. We conclude that the helmet-chin PET with the spherical arrangement constructed from the crystal block sized at 42×42×20 mm{sup 3} has better imaging performance especially at the upper part of the brain compared to the multi-ring arrangement while keeping similar

Recent advances in the preparation and application of monolithic capillary columns in separation science

Energy Technology Data Exchange (ETDEWEB)

Hong, Tingting; Yang, Xi; Xu, Yujing [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing, 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing, 210009 (China); Ji, Yibing, E-mail: jiyibing@msn.com [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing, 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing, 210009 (China)

2016-08-10

Novel column technologies involving various materials and efficient reactions have been investigated for the fabrication of monolithic capillary columns in the field of analytical chemistry. In addition to the development of these miniaturized systems, a variety of microscale separation applications have achieved noteworthy results, providing a stepping stone for new types of chromatographic columns with improved efficiency and selectivity. Three novel strategies for the preparation of capillary monoliths, including ionic liquid-based approaches, nanoparticle-based approaches and “click chemistry”, are highlighted in this review. Furthermore, we present the employment of state-of-the-art capillary monolithic stationary phases for enantioseparation, solid-phase microextraction, mixed-mode separation and immobilized enzyme reactors. The review concludes with recommendations for future studies and improvements in this field of research. - Highlights: • Preparation of novel monolithic capillary columns have shown powerful potential in analytical chemistry field. • Various materials including ionic liquids and nanoparticles involved into capillary monolithic micro-devices are concluded. • Click chemistry strategy applied for preparing monolithic capillary columns is reviewed. • Recent strategies utilized in constructing different capillary monoliths for enantiomeric separation are summarized. • Advancement of capillary monoliths for complex samples analysis is comprehensively described.

Recent advances in the preparation and application of monolithic capillary columns in separation science

International Nuclear Information System (INIS)

Hong, Tingting; Yang, Xi; Xu, Yujing; Ji, Yibing

2016-01-01

Novel column technologies involving various materials and efficient reactions have been investigated for the fabrication of monolithic capillary columns in the field of analytical chemistry. In addition to the development of these miniaturized systems, a variety of microscale separation applications have achieved noteworthy results, providing a stepping stone for new types of chromatographic columns with improved efficiency and selectivity. Three novel strategies for the preparation of capillary monoliths, including ionic liquid-based approaches, nanoparticle-based approaches and “click chemistry”, are highlighted in this review. Furthermore, we present the employment of state-of-the-art capillary monolithic stationary phases for enantioseparation, solid-phase microextraction, mixed-mode separation and immobilized enzyme reactors. The review concludes with recommendations for future studies and improvements in this field of research. - Highlights: • Preparation of novel monolithic capillary columns have shown powerful potential in analytical chemistry field. • Various materials including ionic liquids and nanoparticles involved into capillary monolithic micro-devices are concluded. • Click chemistry strategy applied for preparing monolithic capillary columns is reviewed. • Recent strategies utilized in constructing different capillary monoliths for enantiomeric separation are summarized. • Advancement of capillary monoliths for complex samples analysis is comprehensively described.

Shear bond strength of indirect composite material to monolithic zirconia.

Science.gov (United States)

Sari, Fatih; Secilmis, Asli; Simsek, Irfan; Ozsevik, Semih

2016-08-01

This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05). Bond strength was significantly lower in untreated specimens than in sandblasted specimens (Pcomposite material and monolithic zirconia.

Technology development for SOI monolithic pixel detectors

International Nuclear Information System (INIS)

Marczewski, J.; Domanski, K.; Grabiec, P.; Grodner, M.; Jaroszewicz, B.; Kociubinski, A.; Kucharski, K.; Tomaszewski, D.; Caccia, M.; Kucewicz, W.; Niemiec, H.

2006-01-01

A monolithic detector of ionizing radiation has been manufactured using silicon on insulator (SOI) wafers with a high-resistivity substrate. In our paper the integration of a standard 3 μm CMOS technology, originally designed for bulk devices, with fabrication of pixels in the bottom wafer of a SOI substrate is described. Both technological sequences have been merged minimizing thermal budget and providing suitable properties of all the technological layers. The achieved performance proves that fully depleted monolithic active pixel matrix might be a viable option for a wide spectrum of future applications

Crystals against cancer

CERN Multimedia

2009-01-01

This is a remarkable example of direct technology transfer from particle physics to medicine. Clinical trials have begun in Portugal on a new medical imaging system for the diagnosis of breast cancer, which uses positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

Novel crystal timing calibration method based on total variation

Science.gov (United States)

Yu, Xingjian; Isobe, Takashi; Watanabe, Mitsuo; Liu, Huafeng

2016-11-01

A novel crystal timing calibration method based on total variation (TV), abbreviated as ‘TV merge’, has been developed for a high-resolution positron emission tomography (PET) system. The proposed method was developed for a system with a large number of crystals, it can provide timing calibration at the crystal level. In the proposed method, the timing calibration process was formulated as a linear problem. To robustly optimize the timing resolution, a TV constraint was added to the linear equation. Moreover, to solve the computer memory problem associated with the calculation of the timing calibration factors for systems with a large number of crystals, the merge component was used for obtaining the crystal level timing calibration values. Compared with other conventional methods, the data measured from a standard cylindrical phantom filled with a radioisotope solution was sufficient for performing a high-precision crystal-level timing calibration. In this paper, both simulation and experimental studies were performed to demonstrate the effectiveness and robustness of the TV merge method. We compare the timing resolutions of a 22Na point source, which was located in the field of view (FOV) of the brain PET system, with various calibration techniques. After implementing the TV merge method, the timing resolution improved from 3.34 ns at full width at half maximum (FWHM) to 2.31 ns FWHM.

Monolithic Chip-Integrated Absorption Spectrometer from 3-5 microns, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A monolithically integrated indium phosphide (InP) to silicon-on-sapphire (SoS) platform is being proposed for a monolithic portable or handheld spectrometer between...

Comparison of PET/CT with Sequential PET/MRI Using an MR-Compatible Mobile PET System.

Science.gov (United States)

Nakamoto, Ryusuke; Nakamoto, Yuji; Ishimori, Takayoshi; Fushimi, Yasutaka; Kido, Aki; Togashi, Kaori

2018-05-01

The current study tested a newly developed flexible PET (fxPET) scanner prototype. This fxPET system involves dual arc-shaped detectors based on silicon photomultipliers that are designed to fit existing MRI devices, allowing us to obtain fused PET and MR images by sequential PET and MR scanning. This prospective study sought to evaluate the image quality, lesion detection rate, and quantitative values of fxPET in comparison with conventional whole-body (WB) PET and to assess the accuracy of registration. Methods: Seventeen patients with suspected or known malignant tumors were analyzed. Approximately 1 h after intravenous injection of 18 F-FDG, WB PET/CT was performed, followed by fxPET and MRI. For reconstruction of fxPET images, MRI-based attenuation correction was applied. The quality of fxPET images was visually assessed, and the number of detected lesions was compared between the 2 imaging methods. SUV max and maximum average SUV within a 1 cm 3 spheric volume (SUV peak ) of lesions were also compared. In addition, the magnitude of misregistration between fxPET and MR images was evaluated. Results: The image quality of fxPET was acceptable for diagnosis of malignant tumors. There was no significant difference in detectability of malignant lesions between fxPET and WB PET ( P > 0.05). However, the fxPET system did not exhibit superior performance to the WB PET system. There were strong positive correlations between the 2 imaging modalities in SUV max (ρ = 0.88) and SUV peak (ρ = 0.81). SUV max and SUV peak measured with fxPET were approximately 1.1-fold greater than measured with WB PET. The average misregistration between fxPET and MR images was 5.5 ± 3.4 mm. Conclusion: Our preliminary data indicate that running an fxPET scanner near an existing MRI system provides visually and quantitatively acceptable fused PET/MR images for diagnosis of malignant lesions. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

Surface characteristics and antibacterial activity of a silver-doped carbon monolith

Directory of Open Access Journals (Sweden)

Marija Vukčević et al

2008-01-01

Full Text Available A carbon monolith with a silver coating was prepared and its antimicrobial behaviour in a flow system was examined. The functional groups on the surface of the carbon monolith were determined by temperature-programmed desorption and Boehm's method, and the point of zero charge was determined by mass titration. The specific surface area was examined by N2 adsorption using the Brunauer, Emmett and Teller (BET method. As a test for the surface activity, the deposition of silver from an aqueous solution of a silver salt was used. The morphology and structure of the silver coatings were characterized by scanning electron microscopy and x-ray diffraction. The resistance to the attrition of the silver deposited on the carbon monolith was tested. The antimicrobial activity of the carbon monolith with a silver coating was determined using standard microbiological methods. Carbon monolith samples with a silver coating showed good antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans, and are therefore suitable for water purification, particularly as personal disposable water filters with a limited capacity.

Comparison between PET/MR and PET/CT in evaluation of oncological patients%PET/MR与PET/CT的对比研究

Institute of Scientific and Technical Information of China (English)

徐白萱; 富丽萍; 关志伟; 尹大一; 刘家金; 杨晖; 张锦明; 陈英茂; 安宁豫

2014-01-01

Objective To verify the feasibility of the integrated PET/MR for oncological applications by comparing PET/MR with PET/CT in terms of lesion detection and quantitative measurement.Methods A total of 277 patients (165 males,112 females,average age (52.9± 12.6) years) voluntarily participated in this same-day PET/CT and PET/MR comparative study.The time interval between the two studies was 15-35 min.PET/CT images were acquired and reconstructed following standard protocols.PET/MR covered the body trunk with a sequence combination of transverse T1 weighted imaging (WI) 3D-volumetric interpolated breath-hold,T2WI turbo spin echo with fat saturation,diffusion-weighted imaging,and simultaneous PET acquisition.PET images were reconstructed by vender-provided attenuation correction methods.The results of PET/CT and PET/MR were regarded as positive if any modality (CT,PET or MRI) was positive.SUVmax was obtained by the manually drawn ROI.Detection rates were compared with x2 test and SUVmax from the two modalities was analyzed with Spearman correlation analysis.Results A total of 353 lesions were detected in 220 patients.Compared to PET/CT,PET/MR revealed 30 additional true-positive lesions,while missed 6.The detection rates between PET/CT and PET/MR were significantly different (P＜0.05).The lesion-based and patient-based consistency was 89.8％ (317/353) and 85.9％ (189/220),respectively.There were significant correlations of SUVmax between PET/MR and PET/CT for lesions(rs =0.91,P＜0.01) and for normal tissues(rs =0.62-0.76,all P＜0.01).Conclusions With reference to PET/CT,integrated PET/MR may provide comparable semi-quantitative measurements of pathological lesions as well as normal tissues.Integrated PET/MR may be more effective to detect lesions in abdomen and pelvis.%目的 通过与PET/CT在病灶检测及定量分析方面的比较,论证PET/MR一体机应用于临床的可行性.方法 2012年5月至2013年2月共300例患者同天间隔15 ～ 35 min行PET/CT和PET

Molecularly Imprinted Porous Monolithic Materials from Melamine-Formaldehyde for Selective Trapping of Phosphopeptides

DEFF Research Database (Denmark)

Liu, Mingquan; Tran, Tri Minh; Abbas Elhaj, Ahmed Awad

2017-01-01

monoliths, chosen based on the combination of meso- and macropores providing optimal percolative flow and accessible surface area, was synthesized in the presence of N-Fmoc and O-Et protected phosphoserine and phosphotyrosine to prepare molecularly imprinted monoliths with surface layers selective...... for phosphopeptides. These imprinted monoliths were characterized alongside nonimprinted monoliths by a variety of techniques and finally evaluated by liquid chromatography-mass spectrometry in the capillary format to assess their abilities to trap and release phosphorylated amino acids and peptides from partly...

Pet Problems at Home: Pet Problems in the Community.

Science.gov (United States)

Soltow, Willow

1984-01-01

Discusses problems of pets in the community, examining the community's role related to disruptive pets and pet overpopulation. Also discusses pet problems at home, offering advice on selecting a pet, meeting a pet's needs, and disciplining pets. Includes a list of books, films/filmstrips, teaching materials, and various instructional strategies.…

Photoinitiated grafting of porous polymer monoliths and thermoplastic polymers for microfluidic devices

Science.gov (United States)

Frechet, Jean M. J. [Oakland, CA; Svec, Frantisek [Alameda, CA; Rohr, Thomas [Leiden, NL

2008-10-07

A microfluidic device preferably made of a thermoplastic polymer that includes a channel or a multiplicity of channels whose surfaces are modified by photografting. The device further includes a porous polymer monolith prepared via UV initiated polymerization within the channel, and functionalization of the pore surface of the monolith using photografting. Processes for making such surface modifications of thermoplastic polymers and porous polymer monoliths are set forth.

Digital signal processing applied to crystal identification in Positron Emission Tomography dedicated to small animals

International Nuclear Information System (INIS)

Fontaine, Rejean; Viscogliosi, Nicolas; Semmaoui, Hicham; Belanger, Francois; Lemieux, Francois; Tetrault, Marc-Andre; Michaud, Jean-Baptiste; Berard, Philippe; Cadorette, Jules; Pepin, Catherine M.; Lecomte, Roger

2007-01-01

The recent introduction of all-digital electronic architecture in Positron Emission Tomography (PET) scanners, enables new paradigms to be explored for extracting relevant information from the detector signals, such as energy, time and crystal identification. The LabPET TM small animal scanner, which implements free-running 45-MHz sampling directly at the output of the charge sensitive preamplifiers, provides an excellent platform to test such advanced digital algorithms. A real-time identification method, based on an Auto-Regressive Moving-Average (ARMA) scheme, was tested for discriminating between LYSO (t r ∼40 ns) and LGSO (t r ∼65 ns) scintillators in phoswich detectors, coupled to a single Avalanche Photodiode (APD). Even with a low energy threshold of 250 keV applied individually, error rates 10%, typically with conventional analog pulse shape discrimination techniques. Such digital crystal identification techniques can be readily implemented with phoswich detectors for improving spatial resolution in PET, either by increasing crystal pixellization or by mitigating parallax errors through depth-of-interaction determination. It also allows to reduce the event rate presented to the real-time coincidence engine by applying a low energy limit at the crystal granularity and rejecting more Compton photons

Metal oxide nanorod arrays on monolithic substrates

Energy Technology Data Exchange (ETDEWEB)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

2018-01-02

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

Fine-grain concrete from mining waste for monolithic construction

Science.gov (United States)

Lesovik, R. V.; Ageeva, M. S.; Lesovik, G. A.; Sopin, D. M.; Kazlitina, O. V.; Mitrokhin, A. A.

2018-03-01

The technology of a monolithic construction is a well-established practice among most Russian real estate developers. The strong points of the technology are low cost of materials and lower demand for qualified workers. The monolithic construction uses various types of reinforced slabs and foamed concrete, since they are easy to use and highly durable; they also need practically no additional treatment.

CHARACTERIZATION OF MONOLITHIC FUEL FOIL PROPERTIES AND BOND STRENGTH

International Nuclear Information System (INIS)

D E Burkes; D D Keiser; D M Wachs; J S Larson; M D Chapple

2007-01-01

Understanding fuel foil mechanical properties, and fuel/cladding bond quality and strength in monolithic plates is an important area of investigation and quantification. Specifically, what constitutes an acceptable monolithic fuel--cladding bond, how are the properties of the bond measured and determined, and what is the impact of fabrication process or change in parameters on the level of bonding? Currently, non-bond areas are quantified employing ultrasonic determinations that are challenging to interpret and understand in terms of irradiation impact. Thus, determining mechanical properties of the fuel foil and what constitutes fuel/cladding non-bonds is essential to successful qualification of monolithic fuel plates. Capabilities and tests related to determination of these properties have been implemented at the INL and are discussed, along with preliminary results

Growth of rare-earth doped single crystal yttrium aluminum garnet fibers

Science.gov (United States)

Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Cheng, Long; Rand, Stephen C.; Li, Yuan; Johnson, Eric G.

2018-02-01

Rare-earth doped single crystal (SC) yttrium aluminum garnet (YAG) fibers have great potential as high-power laser gain media. SC fibers combine the superior material properties of crystals with the advantages of a fiber geometry. Improving processing techniques, growth of low-loss YAG SC fibers have been reported. A low-cost technique that allows for the growth of optical quality Ho:YAG single crystal (SC) fibers with different dopant concentrations have been developed and discussed. This technique is a low-cost sol-gel based method which offers greater flexibility in terms of dopant concentration. Self-segregation of Nd ions in YAG SC fibers have been observed. Such a phenomenon can be utilized to fabricate monolithic SC fibers with graded index.

Controlling retention, selectivity and magnitude of EOF by segmented monolithic columns consisting of octadecyl and naphthyl monolithic segments--applications to RP-CEC of both neutral and charged solutes.

Science.gov (United States)

Karenga, Samuel; El Rassi, Ziad

2011-04-01

Monolithic capillaries made of two adjoining segments each filled with a different monolith were introduced for the control and manipulation of the electroosmotic flow (EOF), retention and selectivity in reversed phase-capillary electrochromatography (RP-CEC). These columns were called segmented monolithic columns (SMCs) where one segment was filled with a naphthyl methacrylate monolith (NMM) to provide hydrophobic and π-interactions, while the other segment was filled with an octadecyl acrylate monolith (ODM) to provide solely hydrophobic interaction. The ODM segment not only provided hydrophobic interactions but also functioned as the EOF accelerator segment. The average EOF of the SMC increased linearly with increasing the fractional length of the ODM segment. The neutral SMC provided a convenient way for tuning EOF, selectivity and retention in the absence of annoying electrostatic interactions and irreversible solute adsorption. The SMCs allowed the separation of a wide range of neutral solutes including polycyclic aromatic hydrocarbons (PAHs) that are difficult to separate using conventional alkyl-bonded stationary phases. In all cases, the k' of a given solute was a linear function of the fractional length of the ODM or NMM segment in the SMCs, thus facilitating the tailoring of a given SMC to solve a given separation problem. At some ODM fractional length, the fabricated SMC allowed the separation of charged solutes such as peptides and proteins that could not otherwise be achieved on a monolithic column made from NMM as an isotropic stationary phase due to the lower EOF exhibited by this monolith. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of a Cherenkov TOF-PET module

Science.gov (United States)

Korpar, S.; Dolenec, R.; Križan, P.; Pestotnik, R.; Stanovnik, A.

2013-12-01

An apparatus, consisting of two PbF2 crystals, each coupled to a multichannel plate photomultiplier (MCP-PMT), has been constructed in order to measure the time-of-flight (TOF) of the two 511 keV annihilation photons produced in positron emission tomography (PET). Excellent timing is achieved by detecting the prompt Cherenkov photons produced by the absorption of the 511 keV gamma photons. The present work describes the measurement and image reconstruction of two 22Na point sources. In addition, the influence of the radiator thickness and the Cherenkov light absorption cut-off of the crystal on the efficiency and the timing resolution have been studied by Monte Carlo simulation.

A phoswich detector design for improved spatial sampling in PET

Science.gov (United States)

Thiessen, Jonathan D.; Koschan, Merry A.; Melcher, Charles L.; Meng, Fang; Schellenberg, Graham; Goertzen, Andrew L.

2018-02-01

Block detector designs, utilizing a pixelated scintillator array coupled to a photosensor array in a light-sharing design, are commonly used for positron emission tomography (PET) imaging applications. In practice, the spatial sampling of these designs is limited by the crystal pitch, which must be large enough for individual crystals to be resolved in the detector flood image. Replacing the conventional 2D scintillator array with an array of phoswich elements, each consisting of an optically coupled side-by-side scintillator pair, may improve spatial sampling in one direction of the array without requiring resolving smaller crystal elements. To test the feasibility of this design, a 4 × 4 phoswich array was constructed, with each phoswich element consisting of two optically coupled, 3 . 17 × 1 . 58 × 10mm3 LSO crystals co-doped with cerium and calcium. The amount of calcium doping was varied to create a 'fast' LSO crystal with decay time of 32.9 ns and a 'slow' LSO crystal with decay time of 41.2 ns. Using a Hamamatsu R8900U-00-C12 position-sensitive photomultiplier tube (PS-PMT) and a CAEN V1720 250 MS/s waveform digitizer, we were able to show effective discrimination of the fast and slow LSO crystals in the phoswich array. Although a side-by-side phoswich array is feasible, reflections at the crystal boundary due to a mismatch between the refractive index of the optical adhesive (n = 1 . 5) and LSO (n = 1 . 82) caused it to behave optically as an 8 × 4 array rather than a 4 × 4 array. Direct coupling of each phoswich element to individual photodetector elements may be necessary with the current phoswich array design. Alternatively, in order to implement this phoswich design with a conventional light sharing PET block detector, a high refractive index optical adhesive is necessary to closely match the refractive index of LSO.

Novel design of a parallax free Compton enhanced PET scanner

International Nuclear Information System (INIS)

Braem, A.; Chamizo, M.; Chesi, E.; Colonna, N.; Cusanno, F.; De Leo, R.; Garibaldi, F.; Joram, C.; Marrone, S.; Mathot, S.; Nappi, E.; Schoenahl, F.; Seguinot, J.; Weilhammer, P.; Zaidi, H.

2004-01-01

Molecular imaging by PET is a powerful tool in modern clinical practice for cancer diagnosis. Nevertheless, improvements are needed with respect to the spatial resolution and sensitivity of the technique for its application to specific human organs (breast, prostate, brain, etc.), and to small animals. Presently, commercial PET scanners do not detect the depth of interaction of photons in scintillators, which results in a not negligible parallax error. We describe here a novel concept of PET scanner design that provides full three-dimensional (3D) gamma reconstruction with high spatial resolution over the total detector volume, free of parallax errors. It uses matrices of long scintillators read at both ends by hybrid photon detectors. This so-called 3D axial concept also enhances the gamma detection efficiency since it allows one to reconstruct a significant fraction of Compton scattered events. In this note, we describe the concept, a possible design and the expected performance of this new PET device. We also report about first characterization measurements of 10 cm long YAP:Ce scintillation crystals

Methacrylate-bonded covalent-organic framework monolithic columns for high performance liquid chromatography.

Science.gov (United States)

Liu, Li-Hua; Yang, Cheng-Xiong; Yan, Xiu-Ping

2017-01-06

Covalent-organic frameworks (COFs) are a newfangled class of intriguing microporous materials. Considering their unique properties, COFs should be promising as packing materials for high performance liquid chromatography (HPLC). However, the irregular shape and sub-micrometer size of COFs synthesized via the traditional methods render the main obstacles for the application of COFs in HPLC. Herein, we report the preparation of methacrylate-bonded COF monolithic columns for HPLC to overcome the above obstacles. The prepared COF bonded monolithic columns not only show good homogeneity and permeability, but also give high column efficiency, good resolution and precision for HPLC separation of small molecules including polycyclic aromatic hydrocarbons, phenols, anilines, nonsteroidal anti-inflammatory drugs and benzothiophenes. Compared with the bare polymer monolithic column, the COF bonded monolithic columns show enhanced hydrophobic, π-π and hydrogen bond interactions in reverse phase HPLC. The results reveal the great potential of COF bonded monoliths for HPLC and COFs in separation sciences. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests

OpenAIRE

Mustafa Demir; Türkay Toklu; Mohammad Abuqbeitah; Hüseyin Çetin; H. Sezer Sezgin; Nami Yeyin; Kerim Sönmezoğlu

2018-01-01

Objective: The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor. Methods: According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated...

Evaluation of PET Scanner Performance in PET/MR and PET/CT Systems: NEMA Tests

OpenAIRE

Demir, Mustafa; Toklu, Türkay; Abuqbeitah, Mohammad; Çetin, Hüseyin; Sezgin, H. Sezer; Yeyin, Nami; Sönmezoğlu, Kerim

2018-01-01

Objective: The aim of the present study was to compare the performance of positron emission tomography (PET) component of PET/computed tomography (CT) with new emerging PET/magnetic resonance (MR) of the same vendor. Methods: According to National Electrical Manufacturers Association NU2-07, five separate experimental tests were performed to evaluate the performance of PET scanner of General Electric GE company; SIGNATM model PET/MR and GE Discovery 710 model PET/CT. The main investigated asp...

Two-dimensional thermal analysis of radial heat transfer of monoliths in small-scale steam methane reforming

DEFF Research Database (Denmark)

Cui, Xiaoti; Kær, Søren Knudsen

2018-01-01

Monolithic catalysts have received increasing attention for application in the small-scale steam methane reforming process. The radial heat transfer behaviors of monolith reformers were analyzed by two-dimensional computational fluid dynamic (CFD) modeling. A parameter study was conducted...... by a large number of simulations focusing on the thermal conductivity of the monolith substrate, washcoat layer, wall gap, radiation heat transfer and the geometric parameters (cell density, porosity and diameter of monolith). The effective radial thermal conductivity of the monolith structure, kr......,eff, showed good agreement with predictions made by the pseudo-continuous symmetric model. This influence of the radiation heat transfer is low for highly conductive monoliths. A simplified model has been developed to evaluate the importance of radiation for monolithic reformers under different conditions...

A novel surface modification technique for forming porous polymer monoliths in poly(dimethylsiloxane).

Science.gov (United States)

Burke, Jeffrey M; Smela, Elisabeth

2012-03-01

A new method of surface modification is described for enabling the in situ formation of homogenous porous polymer monoliths (PPMs) within poly(dimethylsiloxane) (PDMS) microfluidic channels that uses 365 nm UV illumination for polymerization. Porous polymer monolith formation in PDMS can be challenging because PDMS readily absorbs the monomers and solvents, changing the final monolith morphology, and because PDMS absorbs oxygen, which inhibits free-radical polymerization. The new approach is based on sequentially absorbing a non-hydrogen-abstracting photoinitiator and the monomers methyl methacrylate and ethylene diacrylate within the walls of the microchannel, and then polymerizing the surface treatment polymer within the PDMS, entangled with it but not covalently bound. Four different monolith compositions were tested, all of which yielded monoliths that were securely anchored and could withstand pressures exceeding the bonding strength of PDMS (40 psi) without dislodging. One was a recipe that was optimized to give a larger average pore size, required for low back pressure. This monolith was used to concentrate and subsequently mechanical lyse B lymphocytes.

Large microwave tunability of GaAs-based multiferroic heterostructure for applications in monolithic microwave integrated circuits

International Nuclear Information System (INIS)

Chen Yajie; Gao Jinsheng; Vittoria, C; Harris, V G; Heiman, D

2010-01-01

Microwave magnetoelectric coupling in a ferroelectric/ferromagnetic/semiconductor multiferroic (MF) heterostructure, consisting of a Co 2 MnAl epitaxial film grown on a GaAs substrate bonded to a lead magnesium niobate-lead titanate (PMN-PT) crystal, is reported. Ferromagnetic resonance measurements were carried out at X-band under the application of electric fields. Results indicate a frequency tuning of 125 MHz for electric field strength of 8 kV cm -1 resulting in a magnetoelectric coupling coefficient of 3.4 Oe cm kV -1 . This work explores the potential of electronically controlled MF devices for use in future monolithic microwave integrated circuits.

Affinity monolith chromatography: A review of principles and recent analytical applications

Science.gov (United States)

Pfaunmiller, Erika L.; Paulemond, Marie Laura; Dupper, Courtney M.; Hage, David S.

2012-01-01

Affinity monolith chromatography (AMC) is a type of liquid chromatography that uses a monolithic support and a biologically-related binding agent as a stationary phase. AMC is a powerful method for the selective separation, analysis or studies of specific target compounds in a sample. This review discusses the basic principles of AMC and recent developments or applications of this method, with particular emphasis being given to work that has appeared in the last five years. Various materials that have been used to prepare columns for AMC are examined, including organic monoliths, silica monoliths, agarose monoliths and cryogels. These supports have been used in AMC for formats that have ranged from traditional columns to disks, microcolumns and capillaries. Many binding agents have also been employed in AMC, such as antibodies, enzymes, proteins, lectins, immobilized metal-ions and dyes. Some applications that have been reported with these binding agents in AMC are bioaffinity chromatography, immunoaffinity chromatography or immunoextraction, immobilized metal-ion affinity chromatography, dye-ligand affinity chromatography, chiral separations and biointeraction studies. Examples are presented from fields that include analytical chemistry, pharmaceutical analysis, clinical testing and biotechnology. Current trends and possible future directions in AMC are also discussed. PMID:23187827

Preparation of porous polymer monoliths featuring enhanced surface coverage with gold nanoparticles

KAUST Repository

Lv, Yongqin

2012-10-01

A new approach to the preparation of porous polymer monoliths with enhanced coverage of pore surface with gold nanoparticles has been developed. First, a generic poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was reacted with cystamine followed by the cleavage of its disulfide bonds with tris(2-carboxylethyl)phosphine, which liberated the desired thiol groups. Dispersions of gold nanoparticles with sizes varying from 5 to 40. nm were then pumped through the functionalized monoliths. The materials were then analyzed using both energy dispersive X-ray spectroscopy and thermogravimetric analysis. We found that the quantity of attached gold was dependent on the size of nanoparticles, with the maximum attachment of more than 60. wt% being achieved with 40. nm nanoparticles. Scanning electron micrographs of the cross sections of all the monoliths revealed the formation of a non-aggregated, homogenous monolayer of nanoparticles. The surface of the bound gold was functionalized with 1-octanethiol and 1-octadecanethiol, and these monolithic columns were used successfully for the separations of proteins in reversed phase mode. The best separations were obtained using monoliths modified with 15, 20, and 30. nm nanoparticles since these sizes produced the most dense coverage of pore surface with gold. © 2012 Elsevier B.V.

MO-F-CAMPUS-J-03: Development of a Human Brain PET for On-Line Proton Beam-Range Verification

Energy Technology Data Exchange (ETDEWEB)

Shao, Yiping [Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: To develop a prototype PET for verifying proton beam-range before each fractionated therapy that will enable on-line re-planning proton therapy. Methods: Latest “edge-less” silicon photomultiplier arrays and customized ASIC readout electronics were used to develop PET detectors with depth-of-interaction (DOI) measurement capability. Each detector consists of one LYSO array with each end coupled to a SiPM array. Multiple detectors can be seamlessly tiled together to form a large detector panel. Detectors with 1.5×1.5 and 2.0×2.0 mm crystals at 20 or 30 mm lengths were studied. Readout of individual SiPM or signal multiplexing was used to transfer 3D interaction position-coded analog signals through flexible-print-circuit cables or PCB board to dedicated ASIC front-end electronics to output digital timing pulses that encode interaction information. These digital pulses can be transferred to, through standard LVDS cables, and decoded by a FPGA-based data acquisition of coincidence events and data transfer. The modular detector and scalable electronics/data acquisition will enable flexible PET system configuration for different imaging geometry. Results: Initial detector performance measurement shows excellent crystal identification even with 30 mm long crystals, ∼18% and 2.8 ns energy and timing resolutions, and around 2–3 mm DOI resolution. A small prototype PET scanner with one detector ring has been built and evaluated, validating the technology and design. A large size detector panel has been fabricated by scaling up from modular detectors. Different designs of resistor and capacitor based signal multiplexing boards were tested and selected based on optimal crystal identification and timing performance. Stackable readout electronics boards and FPGA-based data acquisition boards were developed and tested. A brain PET is under construction. Conclusion: Technology of large-size DOI detector based on SiPM array and advanced readout has been

Microwaves integrated circuits: hybrids and monolithics - fabrication technology

International Nuclear Information System (INIS)

Cunha Pinto, J.K. da

1983-01-01

Several types of microwave integrated circuits are presented together with comments about technologies and fabrication processes; advantages and disadvantages in their utilization are analysed. Basic structures, propagation modes, materials used and major steps in the construction of hybrid thin film and monolithic microwave integrated circuits are described. Important technological applications are revised and main activities of the microelectronics lab. of the University of Sao Paulo (Brazil) in the field of hybrid and monolithic microwave integrated circuits are summarized. (C.L.B.) [pt

Design and simulation of a novel method for determining depth-of-interaction in a PET scintillation crystal array using a single-ended readout by a multi-anode PMT

International Nuclear Information System (INIS)

Ito, Mikiko; Sim, Kwang-Souk; Lee, Jae Sung; Park, Min-Jae; Hong, Seong Jong

2010-01-01

PET detectors with depth-of-interaction (DOI) encoding capability allow high spatial resolution and high sensitivity to be achieved simultaneously. To obtain DOI information from a mono-layer array of scintillation crystals using a single-ended readout, the authors devised a method based on light spreading within a crystal array and performed Monte Carlo simulations with individual scintillation photon tracking to prove the concept. A scintillation crystal array model was constructed using a grid method. Conventional grids are constructed using comb-shaped reflector strips with rectangular teeth to isolate scintillation crystals optically. However, the authors propose the use of triangularly shaped teeth, such that scintillation photons spread only in the x-direction in the upper halves of crystals and in the y-direction in lower halves. DOI positions can be estimated by considering the extent of two-dimensional light dispersion, which can be determined from the multiple anode outputs of a position-sensitive PMT placed under the crystal array. In the main simulation, a crystal block consisting of a 29 x 29 array of 1.5 mm x 1.5 mm x 20 mm crystals and a multi-anode PMT with 16 x 16 pixels were used. The effects of crystal size and non-uniform PMT output gain were also explored by simulation. The DOI resolution estimated for 1.5 x 1.5 x 20 mm 3 crystals was 2.16 mm on average. Although the flood map was depth dependent, each crystal was well identified at all depths when a corner of the crystal array was irradiated with 511 keV gamma rays (peak-to-valley ratio ∼9:1). DOI resolution was better than 3 mm up to a crystal length of 28 mm with a 1.5 x 1.5 mm 2 or 2.0 x 2.0 mm 2 crystal surface area. The devised light-sharing method allowed excellent DOI resolutions to be obtained without the use of dual-ended readout or multiple crystal arrays.

Ordered macro-microporous metal-organic framework single crystals

KAUST Repository

Shen, Kui

2018-01-16

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Ordered macro-microporous metal-organic framework single crystals

Science.gov (United States)

Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

2018-01-01

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional–ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent–induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Ordered macro-microporous metal-organic framework single crystals

KAUST Repository

Shen, Kui; Zhang, Lei; Chen, Xiaodong; Liu, Lingmei; Zhang, Daliang; Han, Yu; Chen, Junying; Long, Jilan; Luque, Rafael; Li, Yingwei; Chen, Banglin

2018-01-01

We constructed highly oriented and ordered macropores within metal-organic framework (MOF) single crystals, opening up the area of three-dimensional-ordered macro-microporous materials (that is, materials containing both macro- and micropores) in single-crystalline form. Our methodology relies on the strong shaping effects of a polystyrene nanosphere monolith template and a double-solvent-induced heterogeneous nucleation approach. This process synergistically enabled the in situ growth of MOFs within ordered voids, rendering a single crystal with oriented and ordered macro-microporous structure. The improved mass diffusion properties of such hierarchical frameworks, together with their robust single-crystalline nature, endow them with superior catalytic activity and recyclability for bulky-molecule reactions, as compared with conventional, polycrystalline hollow, and disordered macroporous ZIF-8.

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Eiji [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)]. E-mail: rush@nirs.go.jp; Kitamura, Keishi [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Kimura, Yuichi [Tokyo Metropolitan Institute of Gerontology, Nakamachi 1-1 Itabashi-ku, Tokyo 173-0022 (Japan); Nishikido, Fumihiko [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Shibuya, Kengo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Yamaya, Taiga [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Murayama, Hideo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)

2007-02-01

In a conventional positron emission tomography (PET) detector, detected events are projected onto a 2D position histogram by an Anger calculation for crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in the entire detector. Peaks which are projected for each crystal in the histogram are blurred, and this causes ICS mispositioning. A depth-of-interaction (DOI) detector has been developed for the small animal PET scanner jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) which was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm{sup 3}. The FP-PMT has a large detective area (49x49 mm{sup 2}) and a small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident {gamma} rays in the crystals including ICS event. We, therefore, propose a novel method for ICS estimation using a statistical pattern recognition algorithm based on a support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using a Monte Carlo calculation. The success rate for ICS event identification is about 78% for non-training data. The SVM can achieve a true subtraction of ICS events from measured events, and it is also useful for random correction in PET.

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal positron emission tomography

International Nuclear Information System (INIS)

Yoshida, Eiji; Kitamura, Keishi; Kimura, Yuichi; Nishikido, Fumihiko; Shibuya, Kengo; Yamaya, Taiga; Murayama, Hideo

2007-01-01

In a conventional positron emission tomography (PET) detector, detected events are projected onto a 2D position histogram by an Anger calculation for crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in the entire detector. Peaks which are projected for each crystal in the histogram are blurred, and this causes ICS mispositioning. A depth-of-interaction (DOI) detector has been developed for the small animal PET scanner jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) which was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm 3 . The FP-PMT has a large detective area (49x49 mm 2 ) and a small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident γ rays in the crystals including ICS event. We, therefore, propose a novel method for ICS estimation using a statistical pattern recognition algorithm based on a support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using a Monte Carlo calculation. The success rate for ICS event identification is about 78% for non-training data. The SVM can achieve a true subtraction of ICS events from measured events, and it is also useful for random correction in PET

Preparation of a zeolite-modified polymer monolith for identification of synthetic colorants in lipsticks

Energy Technology Data Exchange (ETDEWEB)

Wang, Huiqi; Li, Zheng [College of Chemistry, Jilin University, Changchun 130012 (China); Niu, Qian [Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062 (China); Ma, Jiutong [College of Chemistry, Jilin University, Changchun 130012 (China); Jia, Qiong, E-mail: jiaqiong@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

2015-10-30

Graphical abstract: Poly(methacrylic acid-ethylene dimethacrylate) monolithic column embedded with zeolites was prepared and employed for the polymer monolith microextraction of colorants combined with HPLC. - Highlights: • Zeolite, as a kind of mesoporous material, was firstly combined with PMME. • Zeolite@poly(MAA-EDMA) monolith columns were prepared for the enrichment of colorants. • Zeolite@poly(MAA-EDMA) monolith columns demonstrated relatively high extraction capacity. - Abstract: A novel zeolite-modified poly(methacrylic acid-ethylenedimethacrylate) (zeolite@poly(MAA-EDMA)) monolithic column was prepared with the in situ polymerization method and employed in polymer monolith microextraction for the separation and preconcentration of synthetic colorants combined with high performance liquid chromatography. The polymer was characterized by scanning electronmicroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermo-gravimetric analysis. Various parameters affecting the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. The method was applied to the determination of synthetic colorants in lipsticks with recoveries ranged from 70.7% to 109.7%. Compared with conventional methacrylic acid-based monoliths, the developed monolith exhibited high enrichment capacity because of the introduction of zeolites into the preparation process. The extraction efficiency followed the order: zeolite@poly(MAA-EDMA) > poly(MAA-EDMA) > direct HPLC analysis.

High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

Science.gov (United States)

Kato, T.; Kataoka, J.; Nakamori, T.; Kishimoto, A.; Yamamoto, S.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N.; Ikeda, H.; Kamada, K.

2013-05-01

We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 105 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

Evaluation of moderately cooled pure NaI as a scintillator for position-sensitive PET detectors

International Nuclear Information System (INIS)

Wear, J.A.; Karp, J.S.; Haigh, A.T.; Freifelder, R.

1996-01-01

A new evaluation of pure NaI has been performed to determine if moderate cooling would lead to better performance than that of existing, activated NaI(Tl) position-sensitive detectors, particularly at high countrates. Using a freezer, an initial effort was performed to cool the crystal assembly to -90 C (183 K). At this temperature, pure NaI has a decay constant of 35 nsec, a light output which is about 20% that of room temperature NaI(Tl), and an energy resolution of 15%. For the PET applications the signal of room temperature (25 C) NaI(Tl) is normally pulse clipped, reducing the light output to 40% of the unclipped signal and yielding an energy resolution of 10.5%. Since the long decay of NaI(Tl) causes it to suffer more significantly than pure NaI from pre-pulse pileup, the difference in energy resolution between the two crystals at high countrates will be reduced. Also, a significantly shorter trigger deadtime with pure NaI will lead to a reduction in coincidence deadtime losses in PET. Computer simulations of large-area crystals operating at high countrates have been performed to quantify their trigger deadtime behavior and position resolution as a function of light output and pulse decay time. Having gained experience with the practical issues of cooling large crystals, measurements of position resolution have been performed with a NaI bar detector of similar geometry to the NaI(Tl) detectors in use in the PENN-PET scanner

Performance studies towards a TOF-PET sensor using Compton scattering at plastic scintillators

Science.gov (United States)

Kuramoto, M.; Nakamori, T.; Gunji, S.; Kamada, K.; Shoji, Y.; Yoshikawa, A.; Aoki, T.

2018-01-01

We have developed a sensor head for a time-of-flight (TOF) PET scanner using plastic scintillators that have a very fast timing property. Given the very small cross section of photoelectric absorption in plastic scintillators at 511 keV, we use Compton scattering in order to compensate for detection efficiency. The detector will consist of two layers of scatterers and absorbers which are made of plastic and inorganic scintillators such as GAGG:Ce, respectively. Signals are read by monolithic Multi Pixel Photon Counters, and with energy deposits and interaction time stamps are being acquired. The scintillators are built to be capable of resolving interaction position in three dimensions, so that our system has also a function of depth-of-interaction (DOI) PET scanners. TOF resolution of ~ 200 ps (FWHM) is achieved in both cases of using the leading-edge discriminator and time-walk correction and using a configuration sensitive to DOI. Both the position resolution and spectroscopy are demonstrated using the prototype data acquisition system, with Compton scattering events subsequently being obtained. We also demonstrated that the background rejection technique using the Compton cone constraint could be valid with our system.

Comparison of the imaging performances for recently developed monolithic scintillators: CRY018 and CRY019 for dual isotope gamma ray imaging applications

International Nuclear Information System (INIS)

Polito, C.; Pani, R.; Trigila, C.; Cinti, M.N.; Fabbri, A.; Pellegrini, R.; Frantellizzi, V.; Vincentis, G. De; Pani, R.

2017-01-01

The growing interest for new scintillation crystals with outstanding imaging performances (i.e. resolution and efficiency) has suggested the study of recently discovered scintillators named CRY018 and CRY019 . The crystals under investigation are monolithic and have shown enhanced characteristics both for gamma ray spectrometry and for Nuclear Medicine imaging applications such as the dual isotope imaging. Moreover, the non-hygroscopic nature and the absence of afterglow make these scintillators even more attractive for the potential improvement in a wide range of applications. These scintillation crystals show a high energy resolution in the energy range involved in Nuclear Medicine, allowing the discrimination between very close energy values. Moreover, in order to prove their suitability of being powerful imaging systems, the imaging performances like the position linearity and the intrinsic spatial resolution have been evaluated obtaining satisfactory results thanks to the implementation of an optimized algorithm for the images reconstruction.

Comparison of the imaging performances for recently developed monolithic scintillators: CRY018 and CRY019 for dual isotope gamma ray imaging applications

Science.gov (United States)

Polito, C.; Pani, R.; Trigila, C.; Cinti, M. N.; Fabbri, A.; Frantellizzi, V.; De Vincentis, G.; Pellegrini, R.; Pani, R.

2017-01-01

The growing interest for new scintillation crystals with outstanding imaging performances (i.e. resolution and efficiency) has suggested the study of recently discovered scintillators named CRY018 and CRY019. The crystals under investigation are monolithic and have shown enhanced characteristics both for gamma ray spectrometry and for Nuclear Medicine imaging applications such as the dual isotope imaging. Moreover, the non-hygroscopic nature and the absence of afterglow make these scintillators even more attractive for the potential improvement in a wide range of applications. These scintillation crystals show a high energy resolution in the energy range involved in Nuclear Medicine, allowing the discrimination between very close energy values. Moreover, in order to prove their suitability of being powerful imaging systems, the imaging performances like the position linearity and the intrinsic spatial resolution have been evaluated obtaining satisfactory results thanks to the implementation of an optimized algorithm for the images reconstruction.

A Monolithic Perovskite Structure for Use as a Magnetic Regenerator

DEFF Research Database (Denmark)

Pryds, Nini; Clemens, Frank; Menon, Mohan

2011-01-01

A La0.67Ca0.26Sr0.07Mn1.05O3 (LCSM) perovskite was prepared for the first time as a ceramic monolithic regenerator used in a regenerative magnetic refrigeration device. The parameters influencing the extrusion process and the performance of the regenerator, such as the nature of the monolith paste...

A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

Science.gov (United States)

Kamińska, D.; Gajos, A.; Czerwiński, E.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Korcyl, G.; Kowalski, P.; Krzemień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Pawlik-Niedźwiecka, M.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wieczorek, A.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

2016-08-01

We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the { o-Ps }→ 3γ decays with angular and energy resolution equal to σ (θ ) ≈ {0.4°} and σ (E) ≈ 4.1 {keV}, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities.

The Road to the Common PET/CT Detector

Science.gov (United States)

Nassalski, Antoni; Moszynski, Marek; Szczesniak, Tomasz; Wolski, Dariusz; Batsch, Tadeusz

2007-10-01

Growing interest in the development of dual modality positron emission/X-rays tomography (PET/CT) systems prompts researchers to face a new challenge: to acquire both the anatomical and functional information in the same measurement, simultaneously using the same detection system and electronics. The aim of this work was to study a detector consisting of LaBr3, LSO or LYSO pixel crystals coupled to an avalanche photodiode (APD). The measurements covered tests of the detectors in PET and CT modes, respectively. The measurements included the determination of light output, energy resolution, the non-proportionality of the light yield and the time resolution for 511 keV annihilation quanta; analysis also included characterizing the PET detector, and determining the dependence of counting rate versus mean current of the APD in the X-ray detection. In the present experiment, the use of counting and current modes in the CT detection increases the dynamic range of the measured dose of X-rays by a factor of 20, compared to the counting mode alone.

Characterization of Ca co-doped LSO:Ce scintillators coupled to SiPM for PET applications

International Nuclear Information System (INIS)

Bisogni, M.G.; Collazuol, G.M.; Marcatili, S.; Melcher, C.L.; Del Guerra, A.

2011-01-01

Scintillators suitable for PET applications must be characterized by a high efficiency for gamma-ray detection, determined by a high density and atomic number of the crystal; a fast light signal that allows to achieve a good time resolution and to cope with high counting rates; a high light yield for a good energy and time resolution; a good linearity of the light output as a function of the energy to preserve the intrinsic energy resolution of the scintillator. Recently developed LSO:Ce scintillators, co-doped with Ca, have been produced by the University of Tennessee group. They are characterized by the improved performance of most the above-mentioned characteristics. The crystals, initially tested with PMTs, showed a higher light output, faster light pulse, improved energy resolution and reduced afterglow, as compared to the standard LSO:Ce crystals. Even though the PMTs still represent the gold standard photodetectors, the recently available SiPMs are now valid candidate to replace PMTs in the next generation of PET scanners thanks to their compactness, high spatial resolution performances, low bias operating voltage and, most important for combined PET/MRI systems, insensitivity to static and RF fields. In this work we present the performance of Ca co-doped LSO:Ce samples coupled to SiPMs and PMTs. In particular we have assessed their performances by evaluating the energy and time resolution.

Comparative timing measurements of LYSO and LFS-3 to achieve the best time resolution for TOF-PET

CERN Document Server

Doroud, K; Zichichi, A; Zuyeuski, R

2015-01-01

The best Coincidence Time Resolution (CTR) obtained so far – with very short crystals of 3–5 mm in length – reach values between 100 and 150 ps. Such crystals are not really practical for a TOF PET imaging device, since the sensitivity is quite small for the detection of the 511 keV gammas resulting from a positron annihilation. We present our setup and measurements using 15 mm length crystals; a length we regard as reasonable for a TOF-PET scanner. We have used a new series of Silicon Photo-Multipliers (SiPM) manufactured by Hamamatsu. These are the High Fill Factor (HFF) and Low Cross-Talk (LCT) Multi-Pixel Photon Counters (MPPC). We have compared three different crystals, LFS-3 (supplied by Zecotek) and two samples of LYSO (manufactured by Saint Gobain and CPI). We have obtained an excellent value of 148 ps for the Coincidence Time Resolution (CTR) with two LFS-3 crystals (15 mm long) mounted on each side of a 22Na radioactive source with the HFF-MPPCs at 3.3 V over-voltage. Our results are148 ps obt...

Cholesterol-imprinted macroporous monoliths: Preparation and characterization.

Science.gov (United States)

Stepanova, Mariia А; Kinziabulatova, Lilia R; Nikitina, Anna A; Korzhikova-Vlakh, Evgenia G; Tennikova, Tatiana B

2017-11-01

The development of sorbents for selective binding of cholesterol, which is a risk factor for cardiovascular disease, has a great importance for analytical science and medicine. In this work, two series of macroporous cholesterol-imprinted monolithic sorbents differing in the composition of functional monomers (methacrylic acid, butyl methacrylate, 2-hydroxyethyl methacrylate and ethylene dimethacrylate), amount of a template (4, 6 and 8 mol%) used for molecular imprinting, as well as mean pore size were synthesized by in situ free-radical process in stainless steel housing of 50 mm × 4.6 mm i.d. All prepared materials were characterized regarding to their hydrodynamic permeability and porous properties, as well as examined by BET and SEM methods. Imprinting factors, apparent dynamic dissociation constants, the maximum binding capacity, the number of theoretical plates and the height equivalent to a theoretical palate of MIP monoliths at different mobile phase flow rates were determined. The separation of a mixture of structural analogues, namely, cholesterol and prednisolone, was demonstrated. Additionally, the possibility of using the developed monoliths for cholesterol solid-phase extraction from simulated biological solution was shown. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strength of normal sections of NPP composite monolithic constructions with ribbed reinforced panels

International Nuclear Information System (INIS)

Klyashitskij, V.I.; Kirillov, A.P.

1980-01-01

Strength characteristics and recommendations on designing composite-monolytic structures of NPP with ribbed reinforced panels are considered. Ribbed reinforced panel consists of a system of cross ribs joined with a comparatively thin (25 mm thick) plate. The investigations were carried on using models representing columns symmetrically reinforced with reinforced panels with a low percent of reinforcing. The monolithic structures consisting of ribbed reinforced panels and cast concrete for making monoliths as well as monolithic having analogous strength characteristics of extended and compressed zones have similar strengths. It is shown that calculation of supporting power of composite-monolithic structures is performed according to techniques developed for monolithic structures. Necessity of structural transverse fittings no longer arises in case of corresponding calculational substitution of stability of compressed parts of fittings. Supporting power of a structure decreases not more than by 10% in the presence of cracks in the reinforced panels of the compressed zone. Application of composite-monolithic structures during the construction of the Kursk, Smolensk and Chernobylskaya NPPs permitted to decrease labour content and reduce periods of accomplishment of these works which saves over 6 million roubles

Multiple-hit parameter estimation in monolithic detectors.

Science.gov (United States)

Hunter, William C J; Barrett, Harrison H; Lewellen, Tom K; Miyaoka, Robert S

2013-02-01

We examine a maximum-a-posteriori method for estimating the primary interaction position of gamma rays with multiple interaction sites (hits) in a monolithic detector. In assessing the performance of a multiple-hit estimator over that of a conventional one-hit estimator, we consider a few different detector and readout configurations of a 50-mm-wide square cerium-doped lutetium oxyorthosilicate block. For this study, we use simulated data from SCOUT, a Monte-Carlo tool for photon tracking and modeling scintillation- camera output. With this tool, we determine estimate bias and variance for a multiple-hit estimator and compare these with similar metrics for a one-hit maximum-likelihood estimator, which assumes full energy deposition in one hit. We also examine the effect of event filtering on these metrics; for this purpose, we use a likelihood threshold to reject signals that are not likely to have been produced under the assumed likelihood model. Depending on detector design, we observe a 1%-12% improvement of intrinsic resolution for a 1-or-2-hit estimator as compared with a 1-hit estimator. We also observe improved differentiation of photopeak events using a 1-or-2-hit estimator as compared with the 1-hit estimator; more than 6% of photopeak events that were rejected by likelihood filtering for the 1-hit estimator were accurately identified as photopeak events and positioned without loss of resolution by a 1-or-2-hit estimator; for PET, this equates to at least a 12% improvement in coincidence-detection efficiency with likelihood filtering applied.

High density fuels using dispersion and monolithic fuel

Energy Technology Data Exchange (ETDEWEB)

Gomes, Daniel S.; Silva, Antonio T.; Abe, Alfredo Y.; Muniz, Rafael O.R.; Giovedi, Claudia, E-mail: dsgomes@ipen.br, E-mail: teixeira@ipen.br, E-mail: alfredo@ctmsp.mar.mil.br, E-mail: rafael.orm@gmail.com, E-mail: claudia.giovedi@ctmsp.mar.mil.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Universidade de São Paulo (USP), SP (Brazil). Departamento de Engenharia Naval e Oceânica

2017-07-01

Fuel plates used in high-performance research reactors need to be converted to low-enrichment uranium fuel; the fuel option based on a monolithic formulation requires alloys to contain 6 - 10 wt% Mo. In this case, the fuel plates are composed of the metallic alloy U-10Mo surrounded by a thin zirconium layer encapsulated in aluminum cladding. This study reviewed the physical properties of monolithic forms. The constraints produced during the manufacturing process were analyzed and compared to those of dispersed fuel. The bonding process used for dispersion fuels differs from the techniques applied to foil bonding used for pure alloys. The quality of monolithic plates depends on the fabrication method, which usually involves hot isostatic pressing and the thermal annealing effect of residual stress, which degrades the uranium cubic phase. The preservation of the metastable phase has considerable influence on fuel performance. The physical properties of the foil fuel under irradiation are superior to those of aluminum-dispersed fuels. The fuel meat, using zirconium as the diffusion barrier, prevents the interaction layer from becoming excessively thick. The problem with dispersed fuel is breakaway swelling with a medium fission rate. It has been observed that the fuel dispersed in aluminum was minimized in monolithic forms. The pure alloys exhibited a suitable response from a rate at least twice as much as the fission rate of dispersions. The foils can support fissile material concentration combined with a reduced swelling rate. (author)

High density fuels using dispersion and monolithic fuel

International Nuclear Information System (INIS)

Gomes, Daniel S.; Silva, Antonio T.; Abe, Alfredo Y.; Muniz, Rafael O.R.; Giovedi, Claudia; Universidade de São Paulo

2017-01-01

Fuel plates used in high-performance research reactors need to be converted to low-enrichment uranium fuel; the fuel option based on a monolithic formulation requires alloys to contain 6 - 10 wt% Mo. In this case, the fuel plates are composed of the metallic alloy U-10Mo surrounded by a thin zirconium layer encapsulated in aluminum cladding. This study reviewed the physical properties of monolithic forms. The constraints produced during the manufacturing process were analyzed and compared to those of dispersed fuel. The bonding process used for dispersion fuels differs from the techniques applied to foil bonding used for pure alloys. The quality of monolithic plates depends on the fabrication method, which usually involves hot isostatic pressing and the thermal annealing effect of residual stress, which degrades the uranium cubic phase. The preservation of the metastable phase has considerable influence on fuel performance. The physical properties of the foil fuel under irradiation are superior to those of aluminum-dispersed fuels. The fuel meat, using zirconium as the diffusion barrier, prevents the interaction layer from becoming excessively thick. The problem with dispersed fuel is breakaway swelling with a medium fission rate. It has been observed that the fuel dispersed in aluminum was minimized in monolithic forms. The pure alloys exhibited a suitable response from a rate at least twice as much as the fission rate of dispersions. The foils can support fissile material concentration combined with a reduced swelling rate. (author)

Development of the fast and efficient gamma detector using Cherenkov light for TOF-PET

Science.gov (United States)

Canot, C.; Alokhina, M.; Abbon, P.; Bard, J. P.; Tauzin, G.; Yvon, D.; Sharyy, V.

2017-12-01

In this paper we present two configurations of innovative gamma detectors using Cherenkov light for time-of-flight—Positron Emission Tomography (PET). The first uses heavy crystals as a Cherenkov radiator to develop a demonstrator for a whole body PET scanner with high detection efficiency. We demonstrated a 30% detection efficiency and a 180 ps (FWHM) time resolution, mainly limited by the time transit spread of the photomultiplier. The second configuration uses an innovative liquid, the TriMethyl Bismuth, to develop a high precision brain-scanning PET device with time-of-flight capability. According to Geant4 simulation, we expect to reach a precision of 150 ps (FWHM) and an efficiency of about 25%.

A new DOI detector design using discrete crystal array with depth-dependent reflector patterns and single-ended readout

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung-Jae; Lee, Chaeyeong [Department of Radiological Science, Yonsei University, Wonju 26493 (Korea, Republic of); Kang, Jihoon, E-mail: ray.jihoon.kang@gmail.com [Department of Biomedical Engineering, Chonnam National University, 50 Daehak-ro, Yeosu, Jeonnam 59626 (Korea, Republic of); Chung, Yong Hyun, E-mail: ychung@yonsei.ac.kr [Department of Radiological Science, Yonsei University, Wonju 26493 (Korea, Republic of)

2017-01-21

We developed a depth of interaction (DOI) positron emission tomography (PET) detector using depth-dependent reflector patterns in a discrete crystal array. Due to the different reflector patterns at depth, light distribution was changed relative to depth. As a preliminary experiment, we measured DOI detector module crystal identification performance. The crystal consisted of a 9×9 array of 2 mmx2 mmx20 mm lutetium-yttrium oxyorthosilicate (LYSO) crystals. The crystal array was optically coupled to a 64-channel position-sensitive photomultiplier tube with a 2 mmx2 mm anode size and an 18.1 mmx18.1 mm effective area. We obtained the flood image with an Anger-type calculation. DOI layers and 9×9 pixels were well distinguished in the obtained images. Preclinical PET scanners based on this detector design offer the prospect of high and uniform spatial resolution.

A new DOI detector design using discrete crystal array with depth-dependent reflector patterns and single-ended readout

International Nuclear Information System (INIS)

Lee, Seung-Jae; Lee, Chaeyeong; Kang, Jihoon; Chung, Yong Hyun

2017-01-01

We developed a depth of interaction (DOI) positron emission tomography (PET) detector using depth-dependent reflector patterns in a discrete crystal array. Due to the different reflector patterns at depth, light distribution was changed relative to depth. As a preliminary experiment, we measured DOI detector module crystal identification performance. The crystal consisted of a 9×9 array of 2 mmx2 mmx20 mm lutetium-yttrium oxyorthosilicate (LYSO) crystals. The crystal array was optically coupled to a 64-channel position-sensitive photomultiplier tube with a 2 mmx2 mm anode size and an 18.1 mmx18.1 mm effective area. We obtained the flood image with an Anger-type calculation. DOI layers and 9×9 pixels were well distinguished in the obtained images. Preclinical PET scanners based on this detector design offer the prospect of high and uniform spatial resolution.

Sensitivity booster for DOI-PET scanner by utilizing Compton scattering events between detector blocks

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Eiji, E-mail: rush@nirs.go.jp; Tashima, Hideaki; Yamaya, Taiga

2014-11-01

In a conventional PET scanner, coincidence events are measured with a limited energy window for detection of photoelectric events in order to reject Compton scatter events that occur in a patient, but Compton scatter events caused in detector crystals are also rejected. Scatter events within the patient causes scatter coincidences, but inter crystal scattering (ICS) events have useful information for determining an activity distribution. Some researchers have reported the feasibility of PET scanners based on a Compton camera for tracing ICS into the detector. However, these scanners require expensive semiconductor detectors for high-energy resolution. In the Anger-type block detector, single photons interacting with multiple detectors can be obtained for each interacting position and complete information can be gotten just as for photoelectric events in the single detector. ICS events in the single detector have been used to get coincidence, but single photons interacting with multiple detectors have not been used to get coincidence. In this work, we evaluated effect of sensitivity improvement using Compton kinetics in several types of DOI-PET scanners. The proposed method promises to improve the sensitivity using coincidence events of single photons interacting with multiple detectors, which are identified as the first interaction (FI). FI estimation accuracy can be improved to determine FI validity from the correlation between Compton scatter angles calculated on the coincidence line-of-response. We simulated an animal PET scanner consisting of 42 detectors. Each detector block consists of three types of scintillator crystals (LSO, GSO and GAGG). After the simulation, coincidence events are added as information for several depth-of-interaction (DOI) resolutions. From the simulation results, we concluded the proposed method promises to improve the sensitivity considerably when effective atomic number of a scintillator is low. Also, we showed that FI estimate

On-chip steering of entangled photons in nonlinear photonic crystals.

Science.gov (United States)

Leng, H Y; Yu, X Q; Gong, Y X; Xu, P; Xie, Z D; Jin, H; Zhang, C; Zhu, S N

2011-08-16

One promising technique for working toward practical photonic quantum technologies is to implement multiple operations on a monolithic chip, thereby improving stability, scalability and miniaturization. The on-chip spatial control of entangled photons will certainly benefit numerous applications, including quantum imaging, quantum lithography, quantum metrology and quantum computation. However, external optical elements are usually required to spatially control the entangled photons. Here we present the first experimental demonstration of on-chip spatial control of entangled photons, based on a domain-engineered nonlinear photonic crystal. We manipulate the entangled photons using the inherent properties of the crystal during the parametric downconversion, demonstrating two-photon focusing and beam-splitting from a periodically poled lithium tantalate crystal with a parabolic phase profile. These experimental results indicate that versatile and precise spatial control of entangled photons is achievable. Because they may be operated independent of any bulk optical elements, domain-engineered nonlinear photonic crystals may prove to be a valuable ingredient in on-chip integrated quantum optics.

Depth-of-interaction measurement in a single-layer crystal array with a single-ended readout using digital silicon photomultiplier

International Nuclear Information System (INIS)

Lee, Min Sun; Lee, Jae Sung

2015-01-01

We present the first experimental evaluation of a depth-of-interaction (DOI) positron emission tomography (PET) detector using a digital silicon photomultiplier (dSiPM). To measure DOI information from a mono-layer array of scintillation crystals with a single-ended readout, our group has previously proposed and developed a new method based on light spread using triangular reflectors. Since this method relies on measurement of the light distribution, dSiPM, which has a fully digital interface, has several merits for our DOI measurement. The DOI PET detector comprised of a dSiPM sensor (DPC-3200-22-44) coupled with a 14   ×   14 array of 2 mm  ×  2 mm  ×  20 mm unpolished LGSO crystals. All crystals were covered with triangular reflectors. To obtain a good performance of the DOI PET detector, several parameters of detector were selected as a preliminary experiment. Detector performance was evaluated with the selected parameters and the optimal experimental setup, and a DOI measurement was conducted by irradiating the crystal block at five DOI positions spaced at intervals of 4 mm. Maximum-likelihood estimation was employed for DOI positioning and the optimal DOI estimation scheme was also investigated in this study. As a result, the DOI PET detector showed clear crystal identification. The energy resolution (full-width at half-maximum (FWHM)) averaged over all depths was 10.21%  ±  0.15% at 511 keV, and time resolution averaged over all depths was 1198.61   ±   39.70 ps FWHM. The average DOI positioning accuracy for all depths was 74.22%  ±  6.77%, which equates to DOI resolution of 4.67 mm. Energy and DOI resolutions were uniform over all crystal positions except for the back parts of the array. Furthermore, additional simulation studies were conducted to verify the results of our DOI measurement method that is combined with dSiPM technology. In conclusion, our continuous DOI PET detector

Digital signal processing applied to crystal identification in Positron Emission Tomography dedicated to small animals

Energy Technology Data Exchange (ETDEWEB)

Fontaine, Rejean [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada)]. E-mail: Rejean.Fontaine@Usherbrooke.ca; Viscogliosi, Nicolas [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Semmaoui, Hicham [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Belanger, Francois [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Lemieux, Francois [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Tetrault, Marc-Andre [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Michaud, Jean-Baptiste [Department of Electrical and Computer Engineering, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Berard, Philippe [Department of Nuclear Medicine and Radiobiology, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Cadorette, Jules [Department of Nuclear Medicine and Radiobiology, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Pepin, Catherine M. [Department of Nuclear Medicine and Radiobiology, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada); Lecomte, Roger [Department of Nuclear Medicine and Radiobiology, Universite de Sherbrooke, 2500 Boul. Universite, Sherbrooke, Que., J1 K 2R1 (Canada)

2007-02-01

The recent introduction of all-digital electronic architecture in Positron Emission Tomography (PET) scanners, enables new paradigms to be explored for extracting relevant information from the detector signals, such as energy, time and crystal identification. The LabPET{sup TM} small animal scanner, which implements free-running 45-MHz sampling directly at the output of the charge sensitive preamplifiers, provides an excellent platform to test such advanced digital algorithms. A real-time identification method, based on an Auto-Regressive Moving-Average (ARMA) scheme, was tested for discriminating between LYSO (t{sub r}{approx}40 ns) and LGSO (t{sub r}{approx}65 ns) scintillators in phoswich detectors, coupled to a single Avalanche Photodiode (APD). Even with a low energy threshold of 250 keV applied individually, error rates<4% can be achieved, as compared to >10%, typically with conventional analog pulse shape discrimination techniques. Such digital crystal identification techniques can be readily implemented with phoswich detectors for improving spatial resolution in PET, either by increasing crystal pixellization or by mitigating parallax errors through depth-of-interaction determination. It also allows to reduce the event rate presented to the real-time coincidence engine by applying a low energy limit at the crystal granularity and rejecting more Compton photons.

Paladin Enterprises: Monolithic particle physics models global climate.

CERN Multimedia

2002-01-01

Paladin Enterprises presents a monolithic particle model of the universe which will be used by them to build an economical fusion energy system. The model is an extension of the work done by James Clerk Maxwell. Essentially, gravity is unified with electro-magnetic forces and shown to be a product of a closed loop current system, i.e. a particle - monolithic or sub atomic. This discovery explains rapid global climate changes which are evident in the geological record and also provides an explanation for recent changes in the global climate.

Comparison of lesion detection and quantitation of tracer uptake between PET from a simultaneously acquiring whole-body PET/MR hybrid scanner and PET from PET/CT

International Nuclear Information System (INIS)

Wiesmueller, Marco; Schmidt, Daniela; Beck, Michael; Kuwert, Torsten; Gall, Carl C. von; Quick, Harald H.; Navalpakkam, Bharath; Lell, Michael M.; Uder, Michael; Ritt, Philipp

2013-01-01

PET/MR hybrid scanners have recently been introduced, but not yet validated. The aim of this study was to compare the PET components of a PET/CT hybrid system and of a simultaneous whole-body PET/MR hybrid system with regard to reproducibility of lesion detection and quantitation of tracer uptake. A total of 46 patients underwent a whole-body PET/CT scan 1 h after injection and an average of 88 min later a second scan using a hybrid PET/MR system. The radioactive tracers used were 18 F-deoxyglucose (FDG), 18 F-ethylcholine (FEC) and 68 Ga-DOTATATE (Ga-DOTATATE). The PET images from PET/CT (PET CT ) and from PET/MR (PET MR ) were analysed for tracer-positive lesions. Regional tracer uptake in these foci was quantified using volumes of interest, and maximal and average standardized uptake values (SUV max and SUV avg , respectively) were calculated. Of the 46 patients, 43 were eligible for comparison and statistical analysis. All lesions except one identified by PET CT were identified by PET MR (99.2 %). In 38 patients (88.4 %), the same number of foci were identified by PET CT and by PET MR . In four patients, more lesions were identified by PET MR than by PET CT , in one patient PET CT revealed an additional focus compared to PET MR . The mean SUV max and SUV avg of all lesions determined by PET MR were by 21 % and 11 % lower, respectively, than the values determined by PET CT (p CT and PET MR were minor, but statistically significant. Nevertheless, a more detailed study of the quantitative accuracy of PET MR and the factors governing it is needed to ultimately assess its accuracy in measuring tissue tracer concentrations. (orig.)

Broadband EM Performance Characteristics of Single Square Loop FSS Embedded Monolithic Radome

Directory of Open Access Journals (Sweden)

Raveendranath U. Nair

2013-01-01

Full Text Available A monolithic half-wave radome panel, centrally loaded with aperture-type single square loop frequency selective surface (SSL-FSS, is proposed here for broadband airborne radome applications. Equivalent transmission line method in conjunction with equivalent circuit model (ECM is used for modeling the SSL-FSS embedded monolithic half-wave radome panel and evaluating radome performance parameters. The design parameters of the SSL-FSS are optimized at different angles of incidence such that the new radome wall configuration offers superior EM performance from L-band to X-band as compared to the conventional monolithic half-wave slab of identical material and thickness. The superior EM performance of SSL-FSS embedded monolithic radome wall makes it suitable for the design of normal incidence and streamlined airborne radomes.

Small animal simultaneous PET/MRI: initial experiences in a 9.4 T microMRI

Energy Technology Data Exchange (ETDEWEB)

Maramraju, Sri Harsha; Ravindranath, Bosky; Vaska, Paul; Schlyer, David J [Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY (United States); Smith, S David; Schulz, Daniela [Medical Department, Brookhaven National Laboratory, Upton, NY (United States); Junnarkar, Sachin S; Rescia, Sergio [Instrumentation Division, Brookhaven National Laboratory, Upton, NY (United States); Stoll, Sean; Purschke, Martin L; Woody, Craig L [Physics Department, Brookhaven National Laboratory, Upton, NY (United States); Southekal, Sudeepti [Brigham and Women' s Hospital, Boston, MA (United States); Pratte, Jean-Francois, E-mail: schlyer@bnl.gov [Universite de Sherbrooke, Sherbrooke, Quebec (Canada)

2011-04-21

We developed a non-magnetic positron-emission tomography (PET) device based on the rat conscious animal PET that operates in a small-animal magnetic resonance imaging (MRI) scanner, thereby enabling us to carry out simultaneous PET/MRI studies. The PET detector comprises 12 detector blocks, each being a 4 x 8 array of lutetium oxyorthosilicate crystals (2.22 x 2.22 x 5 mm{sup 3}) coupled to a matching non-magnetic avalanche photodiode array. The detector blocks, housed in a plastic case, form a 38 mm inner diameter ring with an 18 mm axial extent. Custom-built MRI coils fit inside the positron-emission tomography (PET) device, operating in transceiver mode. The PET insert is integrated with a Bruker 9.4 T 210 mm clear-bore diameter MRI scanner. We acquired simultaneous PET/MR images of phantoms, of in vivo rat brain, and of cardiac-gated mouse heart using [{sup 11}C]raclopride and 2-deoxy-2-[{sup 18}F]fluoro-d-glucose PET radiotracers. There was minor interference between the PET electronics and the MRI during simultaneous operation, and small effects on the signal-to-noise ratio in the MR images in the presence of the PET, but no noticeable visual artifacts. Gradient echo and high-duty-cycle spin echo radio frequency (RF) pulses resulted in a 7% and a 28% loss in PET counts, respectively, due to high PET counts during the RF pulses that had to be gated out. The calibration of the activity concentration of PET data during MR pulsing is reproducible within less than 6%. Our initial results demonstrate the feasibility of performing simultaneous PET and MRI studies in adult rats and mice using the same PET insert in a small-bore 9.4 T MRI.

Fabrication of interfacial functionalized porous polymer monolith and its adsorption properties of copper ions

International Nuclear Information System (INIS)

Han, Jiaxi; Du, Zhongjie; Zou, Wei; Li, Hangquan; Zhang, Chen

2014-01-01

Highlights: • Interface functionalized PGMA porous monolith was fabricated. • The adsorption capacity of Cu 2+ was 35.3 mg/g. • The effects of porous structure on the adsorption of Cu 2+ were studied. • The adsorption behaviors of porous monolith were studied. - Abstract: The interfacial functionalized poly (glycidyl methacrylate) (PGMA) porous monolith was fabricated and applied as a novel porous adsorbent for copper ions (Cu 2+ ). PGMA porous material with highly interconnected pore network was prepared by concentrated emulsion polymerization template. Then polyacrylic acid (PAA) was grafted onto the interface of the porous monolith by the reaction between the epoxy group on PGMA and a carboxyl group on PAA. Finally, the porous monolith was interfacial functionalized by rich amount of carboxyl groups and could adsorb copper ions effectively. The chemical structure and porous morphology of the porous monolith were measured by Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the effects of pore size distribution, pH value, co-existing ions, contacting time, and initial concentrations of copper ions on the adsorption capacity of the porous adsorbents were studied

Study of pulse shapes in Ge detectors with PET

Energy Technology Data Exchange (ETDEWEB)

Grabmayr, Peter; Hegai, Alexander; Jochum, Josef; Schmitt, Christopher; Schuetz, Ann-Kathrin [Eberhard Karls Univeritaet Tuebingen (Germany); Collaboration: GERDA-Collaboration

2016-07-01

The Gerda collaboration aims to determine the half life of the neutrinoless double beta decay (0νββ) of {sup 76}Ge. For Phase II Gerda wants to reduce the background contribution significantly by active background-suppression techniques. One of such techniques is the pulse shape analysis of signals induced by the interaction of radiation with the detector. The pulse shapes depend not only on the energy of the interacting gamma, the geometry and field configuration but also on the location of interaction in the crystal. The waveform and the location of the interaction in the germanium can be determined by positron-emission-tomography (PET). First results of this novel pulse shape study with the PET will be presented in this talk.

Preparation and characterization of poly-(methacrylatoethyl trimethylammonium chloride-co-vinylbenzyl chloride-co-ethylene dimethacrylate monolith

Directory of Open Access Journals (Sweden)

Eko Malis

2015-05-01

Full Text Available A polymer monolithic column, poly-(methacrylatoethyltrimethylammonium chloride-co-vinylbenzyl chloride-co-ethylene dimethacrylate or poly-(MATE-co-VBC-co-EDMA was successfully prepared in the current study by one-step thermally initiated in situ polymerization, confined in a steel tubing of 0.5 mm i.d. and 1/16” o.d. The monoliths were prepared from methacrylatoethyltrimethylammonium chloride (MATE and vinylbenzyl chloride (VBC as monomer and ethylene dimethacrylate (EDMA as crosslinker using a binary porogen system of 1-propanol and 1,4-butanediol. The inner wall of steel tubing was pretreated with 3-methacryloxypropyl-trimethoxysilane (MAPS. In order to obtain monolith with adequate column efficiency and low flow resistance, some parameters such as total monomer concentration (%T and crosslinker concentration (%C were optimized. The morphology of this monolith was assessed by scanning electron microscopy (SEM. The properties of the monolithic column, such as permeability, binding capacity, and pore size distribution were also characterized in detail. From the results of the characterization of all monolith variation, monolith with %T 30 %C 50 and %T 35 %C 50 give the best characteristic. These monoliths have high permeability, adequate molecular recognition sites (represented with binding capacity value of over 20 mg/mL, and have over 80% flow through pores in their pore structure contribute to low flow resistance. The resulted monolithic columns have promising potential for dual mode liquid chromatography. MATE may contribute for anion-exchange while VBC may responsible for reversed-phase liquid chromatography.

Performance evaluation of SiPM photodetectors for PET imaging in the presence of magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Espana, S., E-mail: samuel@nuclear.fis.ucm.e [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Fraile, L.M.; Herraiz, J.L.; Udias, J.M. [Grupo de Fisica Nuclear, Dpto. Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Desco, M.; Vaquero, J.J. [Unidad de Medicina y Cirugia Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain)

2010-02-01

The multi-pixel photon counter (MPPC) or silicon photomultiplier (SiPM), recently introduced as a solid-state photodetector, consists of an array of Geiger-mode photodiodes (microcells). It is a promising device for PET due to its potential for high photon detection efficiency (PDE) and its foreseeable immunity to magnetic fields. It is also easy to use with simple read-outs, has a high gain and a small size. In this work we evaluate the in field performance of three 1x1 mm{sup 2} (with 100, 400 and 1600 microcells, respectively) and one 6x6 mm{sup 2} (arranged as a 2x2 array) Hamamatsu MPPCs for their use in PET imaging. We examine the dependence of the energy resolution and the gain of these devices on the temperature and reverse bias voltage, when coupled to LYSO scintillator crystals under conditions that one would find in a PET system. We find that the 400 and 1600 microcells models and the 2x2 array are suitable for small-size crystals, like those employed in high resolution small animal scanners. We have confirmed the good performance of these devices up to magnetic fields of 7 T as well as their suitability for performing PET acquisitions in the presence of fast switching gradients and high duty radiofrequency MRI sequences.

Digital silicon photomultiplier readout of a new fast and bright scintillation crystal (Ce:GFAG)

Energy Technology Data Exchange (ETDEWEB)

Lee, Yong-Seok [Department of Bio-convergence Engineering, Korea University, Seoul (Korea, Republic of); Leem, Hyun-Tae [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Yamamoto, Seiichi [Department of Medical Technology, Nagoya University Graduate School of Medicine, Nagoya (Japan); Choi, Yong, E-mail: ychoi@sogang.ac.kr [Molecular Imaging Research & Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Kamada, Kei [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); C& A corporation, Sendai (Japan); Yoshikawa, Akira [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai (Japan); C& A corporation, Sendai (Japan); Institute for Material Research, Tohoku University, Sendai (Japan); Park, Sang-Geon [Department of Electrical & Electronics, Silla University, Pusan (Korea, Republic of); Yeom, Jung-Yeol, E-mail: jungyeol@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul (Korea, Republic of); School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of)

2016-10-01

A new Gadolinium Fine Aluminum Gallate (Ce:GFAG) scintillation crystal with both high energy resolution and fast timing properties has successfully been grown. Compared to Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG), this new inorganic scintillation crystal has a high luminosity similar to and a faster decay time. In this paper, we report on the timing and energy performance results of the new GFAG scintillation crystal read out with digital silicon photomultipliers (dSiPM) for positron emission tomography (PET) application. The best coincidence resolving time (FWHM) of polished 3×3×5 mm{sup 3} crystals was 223±6 ps for GFAG crystals compared to 396±28 ps for GAGG crystals and 131±3 ps for LYSO crystals respectively. An energy resolution (511 keV peak of Na-22) of 10.9±0.2% was attained with GFAG coupled to dSiPM after correcting for saturation effect, compared to 9.5±0.3% for Ce:GAGG crystals and 11.9±0.4% for LYSO crystals respectively. It is expected that this new scintillator may be competitive in terms of overall properties such as energy resolution, timing resolution and growing (raw material) cost, compared to existing scintillators for positron emission tomography (PET).

Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

Directory of Open Access Journals (Sweden)

Cheng Chuantong

2017-07-01

Full Text Available Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

Science.gov (United States)

Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

2017-07-01

Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs) in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

Dual jaw treatment of edentulism using implant-supported monolithic zirconia fixed prostheses.

Science.gov (United States)

Altarawneh, Sandra; Limmer, Bryan; Reside, Glenn J; Cooper, Lyndon

2015-01-01

This case report describes restoration of the edentulous maxilla and mandible with implant supported fixed prostheses using monolithic zirconia, where the incisal edges and occluding surfaces were made of monolithic zirconia. Edentulism is a debilitating condition that can be treated with either a removable or fixed dental prosthesis. The most common type of implant-supported fixed prosthesis is the metal acrylic (hybrid), with ceramo-metal prostheses being used less commonly in complete edentulism. However, both of these prostheses designs are associated with reported complications of screw loosening or fracture and chipping of acrylic resin and porcelain. Monolithic zirconia implant-supported fixed prostheses have the potential for reduction of such complications. In this case, the CAD/CAM concept was utilized in fabrication of maxillary and mandibular screw-retained implant-supported fixed prostheses using monolithic zirconia. Proper treatment planning and execution coupled with utilizing advanced technologies contributes to highly esthetic results. However, long-term studies are required to guarantee a satisfactory long-term outcome of this modality of treatment. This case report describes the clinical and technical procedures involved in fabrication of maxillary and mandibular implant-supported fixed prostheses using monolithic zirconia as a treatment of edentulism, and proposes the possible advantages associated with using monolithic zirconia in eliminating dissimilar interfaces in such prostheses that are accountable for the most commonly occurring technical complication for these prostheses being chipping and fracture of the veneering material. © 2015 Wiley Periodicals, Inc.

The journey: from X-rays to PET-MRI

International Nuclear Information System (INIS)

Sheikh, Tariq Hussain

2010-01-01

has a common patient palette (bed), which travels from the CT gantry to the PET gantry. These advancements have led to better image registration and higher patient throughput. With further developments in crystal design, time of flight processing, CT based partial volume correction, multi-detector CT, short breath holding times, respiratory gating and newer reconstruction algorithms. PET-CTs of today have reached an unprecedented resolution reaching 2 mm across the field of view in the PET component with sub millimeter resolutions in CT. In short we have reached a long way over the last century, from X-Rays to the inception of PET-MRI, the only hindrance is the availability and high cost which we hope will improve in the days to come

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

International Nuclear Information System (INIS)

Song, Tae Yong; Wu Heyu; Komarov, Sergey; Tai, Yuan-Chuan; Siegel, Stefan B

2010-01-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm 3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

Monolitni katalizatori i reaktori: osnovne značajke, priprava i primjena (Monolith catalysts and reactors: preparation and applications

Directory of Open Access Journals (Sweden)

Tomašić, V.

2004-12-01

Full Text Available Monolithic (honeycomb catalysts are continuous unitary structures containing many narrow, parallel and usually straight channels (or passages. Catalytically active components are dispersed uniformly over the whole porous ceramic monolith structure (so-called incorporated monolithic catalysts or are in a layer of porous material that is deposited on the walls of channels in the monolith's structure (washcoated monolithic catalysts. The material of the main monolithic construction is not limited to ceramics but includes metals, as well. Monolithic catalysts are commonly used in gas phase catalytic processes, such as treatment of automotive exhaust gases, selective catalytic reduction of nitrogen oxides, catalytic removal of volatile organic compounds from industrial processes, etc. Monoliths continue to be the preferred support for environmental applications due to their high geometric surface area, different design options, low pressure drop, high temperature durability, mechanical strength, ease of orientation in a reactor and effectiveness as a support for a catalytic washcoat. As known, monolithic catalysts belong to the class of the structured catalysts and/or reactors (in some cases the distinction between "catalyst" and "reactor" has vanished. Structured catalysts can greatly intensify chemical processes, resulting in smaller, safer, cleaner and more energy efficient technologies. Monolith reactors can be considered as multifunctional reactors, in which chemical conversion is advantageously integrated with another unit operation, such as separation, heat exchange, a secondary reaction, etc. Finally, structured catalysts and/or reactors appear to be one of the most significant and promising developments in the field of heterogeneous catalysis and chemical engineering of the recent years. This paper gives a description of the background and perspectives for application and development of monolithic materials. Different methods and techniques

Detection of Cancer with PET and PET/CT in Asymptomatic Volunteers

International Nuclear Information System (INIS)

Chung, Ji In; Choi, Joon Young; Lee, Kyung Han; Kim, Byung Tae; Choi, Yoon Ho; Cho, Han Byoul; Shim, Jae Yong

2009-01-01

We retrospectively investigated the diagnostic performance of 18 F-fluorodeoxyglucose positron emission tomography (PET) and PET/CT for cancer detection in asymptomatic health-check examinees. This study consisted of 5091 PET or PET/CT conducted as part of annual health examination at one hospital from March 1998 to February 2008. To find the incidence of cancers, medical records of the subjects were thoroughly reviewed for a follow-up period of one year. The patterns of formal readings of PET and PET/CT were analyzed to assess the sensitivity and specificity for cancer detection. The histopathology and stage of the cancers were evaluated in relation to the results of PET. Eighty-six cancers (1.7%) were diagnosed within one year after PET or PET/CT. When PET and PET/CT results were combined, the sensitivity was 48.8% and specificity was 81.1% for cancer detection. PET only had a sensitivity of 46.2% and a specificity of 81.4%, and PET/CT only had a sensitivity of 75.0% and a specificity of 78.5% respectively. There were no significant differences in cancer site, stage and histopathology between PET positive and PET negative cancers. In 19.3% of formal readings of PET and PET/CT, further evaluation to exclude malignancy or significant disease was recommended. Head and neck area and upper gastrointestinal tract were commonly recommended sites for further evaluation. PET and PET/CT showed moderate performance for detecting cancers in asymptomatic adults in this study. More experience and further investigation are needed to overcome limitations of PET and PET/CT for cancer screening

Stanley Kubrick and B.F. Skinner : Is a Teaching Machine a Monolith ?

OpenAIRE

浜野, 保樹; ハマノ, ヤスキ; Yasuki, Hamano

1990-01-01

The teaching machine invented by B.F. Skinner was recog-nized as one of few clear achievements of scientific pedagogy and even appeared in SF. Arthur C. Clarke who wrote the script of the SF movie "2001: A Space Odyssey" with Stanley Kubrick wanted to scientifically define a monolith to be a God who had given intelligence to our ancestors. In other words, he wanted to describe a monolith as a teaching machine as well as a God. However Kubrick did not want to make clear about what a monolith i...

III–Vs on Si for photonic applications—A monolithic approach

International Nuclear Information System (INIS)

Wang, Zhechao; Junesand, Carl; Metaferia, Wondwosen; Hu, Chen; Wosinski, Lech; Lourdudoss, Sebastian

2012-01-01

Highlights: ► Monolithic evanescently coupled silicon laser (MECSL) structure treated. ► Optical mode profiles and thermal resistivity of MECSL optimized by simulation. ► MECSL through epitaxial lateral overgrowth (ELOG) of InP on Si exemplified. ► Passive waveguide in MECSL also acts as the defect filtering mask in ELOG. ► Growth of dislocation free thin InP layer on Si by ELOG for MECSL demonstrated. - Abstract: Epitaxial lateral overgrowth (ELOG) technology is demonstrated as a viable technology to realize monolithic integration of III-Vs on silicon. As an alternative to wafer-to-wafer bonding and die-to-wafer bonding, ELOG provides an attractive platform for fabricating discrete and integrated components in high volume at low cost. A possible route for monolithic integration of III–Vs on silicon for silicon photonics is exemplified by the case of a monolithic evanescently coupled silicon laser (MECSL) by combining InP on Si/SiO 2 through ELOG. Passive waveguide in MECSL also acts as the defect filtering mask in ELOG. The structural design of a monolithic evanescently coupled silicon laser (MECSL) and its thermal resistivity are established through simulations. Material studies to realize the above laser through ELOG are undertaken by studying appropriate ELOG pattern designs to achieve InP on narrow regions of silicon. We show that defect-free InP can be obtained on SiO 2 as the first step which paves the way for realizing active photonic devices on Si/SiO 2 waveguides, e.g. an MECSL.

The KFA TierPET: Performance characteristics and measurements

International Nuclear Information System (INIS)

Weber, S.; Herzog, H.; Mueller-Gaertner, H.W.

1996-01-01

We will present first results of the KFA Tier-PET, a positron emission tomograph with flexible geometry dedicated to in vivo studies of small animals. The flexible geometry allows us to change between measurements with high spatial resolution and measurements with increased sensitivity at the cost of resolution. The detectors consist of yttrium aluminum perovskit scintillator arrays which are glued together from 20 x 20 optically isolated crystals, coupled to position sensitive photomultiplier tubes. The fundamental design features concerning crystal dimensions and detector arrangement have been simulated. Based on this data, the definite dimensional outline of the crystals was determined. The YAP:Ce matrix in combination with a position sensitive photomultiplier leads to a detector block with a high spatial resolution. In first measurements a system sensitivity of 1.8 kcps/μCi/ml has been evaluated for a detector-to-detector distance of 16 cm

Investigation of a whole-body DOI-PET system

International Nuclear Information System (INIS)

Ohi, Junichi; Tonami, Hiromichi

2007-01-01

In this study, we were conducting basic research on a whole-body depth of gamma-ray interaction (DOI) positron emission tomography system which provides spatial resolution that is both high and uniform, and also minimizes costs. The detectors consist of double-layer 9x10 GSO/GSO phoswich crystal blocks, a light guide and two rectangular PMTs. Individual crystal sizes are 2.45x5.1x15 mm 3 , and each layer of crystal blocks has a different decay time. Many of the circuit boards used in our current conventional PET system (SET-3000G SHIMADZU Japan) have been optimized for DOI acquisition. The detectors are arranged to form a 332.5 mm radius detection ring, and spatial resolution is obtained from the center to the edge of the 250 mm radius field of view. The effect of DOI was confirmed using a comparison with the non-DOI systems

Translucency and Strength of High Translucency Monolithic Zirconium Oxide Materials

Science.gov (United States)

2016-05-17

Zirconium -Oxide Materials presented at/published to the Journal of General Dentistry with MDWI 41-108, and has been assigned local file #16208. 2...Zirconia-Oxide Materials 6. TITLE OF MATERIAL TO BE PUBLISHED OR PRESENTED: Translucency and Strength of High-Translucency Monolithic Zirconium -Oxide...OBSOLETE 48. DATE Page 3 of 3 Pages Translucency and Strength of High-Translucency Monolithic Zirconium -Oxide Materials Abstract Dental materials

PET

DEFF Research Database (Denmark)

Mariager, Rasmus Mølgaard; Schmidt, Regin; Heiberg, Morten Rievers

PET handler om den hemmelige tjenestes arbejde under den kolde krig 1945-1989. Her fortæller Regin Schmidt, Rasmus Mariager og Morten Heiberg om de mest dramatiske og interessante sager fra PET's arkiv. PET er på flere måder en udemokratisk institution, der er sat til at vogte over demokratiet....... Dens virksomhed er skjult for offentligheden, den overvåger borgernes aktiviteter, og den registrerer følsomme personoplysninger. Historien om PET rejser spørgsmålet om, hvad man skal gøre, når befolkningen i et demokrati er kritisk indstillet over for overvågningen af lovlige politiske aktiviteter......, mens myndighederne mener, at det er nødvendigt for at beskytte demokratiet. PET er på en gang en fortælling om konkrete aktioner og begivenheder i PET's arbejde og et stykke Danmarkshistorie. Det handler om overvågning, spioner, politisk ekstremisme og international terrorisme.  ...

Observations on dual-ended readout of 100 mm long LYSO crystals

Energy Technology Data Exchange (ETDEWEB)

Ur-Rehman, Fazal, E-mail: Fazal@physics.umanitoba.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg (Canada); McIntosh, Bryan [Department of Physics and Astronomy, University of Manitoba, Winnipeg (Canada); Goertzen, Andrew L. [Department of Physics and Astronomy, University of Manitoba, Winnipeg (Canada); Department of Radiology, University of Manitoba, Winnipeg (Canada)

2011-10-01

We are investigating using dual-ended readout of axially oriented long thin scintillator crystals in detectors for a compact geometry, small ring diameter animal PET system. The axial position of interaction is determined from the light sharing between two photodetectors at opposite ends of the crystal. We examine the light output, energy resolution and axial spatial resolution of 1.5-5x2x100 mm{sup 3} polished LYSO crystals by irradiating with an electronically collimated beam of 511 keV photons oriented perpendicular to the long axis and read out at either end by position sensitive photomultiplier tubes (PSPMTs). Three reflector materials, namely Teflon, 3 M enhanced specular reflector (ESR) and black paint are examined for the 2x2x100 mm{sup 3} crystal size. The light output increases and energy resolution improves with the crystal cross-section. Generally, the spatial resolution worsens with increase in crystal cross-section. For the 2x2x100 mm{sup 3} crystal size, the mean energy resolutions of the photopeak over the nine irradiation positions were 14.4{+-}0.4%, 16.0{+-}1.2% and 28.3{+-}2.1% with mean spatial resolutions of 7.0{+-}1.0, 9.4{+-}3.3 and 26.0{+-}5.0 mm using ESR, Teflon and black paint, respectively. ESR reflector gave the best light output, energy and axial spatial resolutions. These characterization results of PSPMT-based dual-ended long LYSO crystals will be useful in the design of detector modules for a highly compact geometry preclinical PET system using this detector technology.

Kinetic analysis of dynamic PET data

Energy Technology Data Exchange (ETDEWEB)

Knittel, B.

1983-12-01

Our goal is to quantify regional physiological processes such as blood flow and metabolism by means of tracer kinetic modeling and positron emission tomography (PET). Compartmental models are one way of characterizing the behavior of tracers in physiological systems. This paper describes a general method of estimating compartmental model rate constants from measurements of the concentration of tracers in blood and tissue, taken at multiple time intervals. A computer program which applies the method is described, and examples are shown for simulated and actual data acquired from the Donner 280-Crystal Positron Tomograph.

Kinetic analysis of dynamic PET data

International Nuclear Information System (INIS)

Knittel, B.

1983-12-01

Our goal is to quantify regional physiological processes such as blood flow and metabolism by means of tracer kinetic modeling and positron emission tomography (PET). Compartmental models are one way of characterizing the behavior of tracers in physiological systems. This paper describes a general method of estimating compartmental model rate constants from measurements of the concentration of tracers in blood and tissue, taken at multiple time intervals. A computer program which applies the method is described, and examples are shown for simulated and actual data acquired from the Donner 280-Crystal Positron Tomograph

A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

International Nuclear Information System (INIS)

Kaminska, D.; Gajos, A.; Czerwinski, E.; Alfs, D.; Bednarski, T.; Bialas, P.; Dulski, K.; Glowacz, B.; Gupta-Sharma, N.; Korcyl, G.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedzwiecki, Sz.; Pawlik-Niedzwiecka, M.; Rudy, Z.; Wieczorek, A.; Zielinski, M.; Moskal, P.; Curceanu, C.; Silarski, M.; Gorgol, M.; Jasinska, B.; Zgardzinska, B.; Hiesmayr, B.C.; Kowalski, P.; Raczynski, L.; Wislicki, W.; Krzemien, W.

2016-01-01

We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the o-Ps → 3γ decays with angular and energy resolution equal to σ(θ) ∼ 0.4 circle and σ(E) ∼ 4.1 keV, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities. (orig.)

A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

Energy Technology Data Exchange (ETDEWEB)

Kaminska, D.; Gajos, A.; Czerwinski, E.; Alfs, D.; Bednarski, T.; Bialas, P.; Dulski, K.; Glowacz, B.; Gupta-Sharma, N.; Korcyl, G.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedzwiecki, Sz.; Pawlik-Niedzwiecka, M.; Rudy, Z.; Wieczorek, A.; Zielinski, M.; Moskal, P. [Jagiellonian University, Faculty of Physics, Astronomy and Applied Computer Science, Krakow (Poland); Curceanu, C.; Silarski, M. [INFN, Laboratori Nazionali di Frascati, CP 13, Frascati (Italy); Gorgol, M.; Jasinska, B.; Zgardzinska, B. [Maria Curie-Sklodowska University, Department of Nuclear Methods, Institute of Physics, Lublin (Poland); Hiesmayr, B.C. [University of Vienna, Faculty of Physics, Vienna (Austria); Kowalski, P.; Raczynski, L.; Wislicki, W. [Swierk Computing Centre, National Centre for Nuclear Research, Otwock-Swierk (Poland); Krzemien, W. [National Centre for Nuclear Research, High Energy Department, Otwock-Swierk (Poland)

2016-08-15

We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the o-Ps → 3γ decays with angular and energy resolution equal to σ(θ) ∼ 0.4 {sup circle} and σ(E) ∼ 4.1 keV, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities. (orig.)

Readout and characterisation of new silicon pixel photodiode array for use in PET

International Nuclear Information System (INIS)

Hooper, P.; Ward, G.; Lerch, R.; Rozenfeld, A.

2002-01-01

Full text: Positron emission tomography (PET) is a functional imaging tool, which is able to quantify physiological, and biochemical processes in vivo using short-lived cyclotron-produced radiotracers. The main physical principle of PET is the simultaneous measurement of two 511 keV photons which are emitted in opposite directions following the annihilation of a positron in tissue. The accuracy of tracking these photons determines the accuracy of localising the radiotracer in the body, which is referred to as the spatial resolution of the system. Compared with conventional single photon imaging with gamma cameras, PET provides superior spatial resolution and sensitivity. However, compared with anatomical imaging techniques, the spatial resolution remains relatively poor at approximately 4-6 mm full width at half maximum (FWHM), compared with 1 mm FWHM for MRI. The Centre for Medical Radiation Physics at the University of Wollongong is developing a new Positron Emission Tomography (PET) detection sub-module that will significantly improve the spatial resolution of PET. The new sub-module design is simple and robust to minimise module assembly complications and is completely independent of photomultiplier tubes. The new sub-module has also been designed to maximise its flexibility for easy sub-module coupling so as to form a complete, customised, detection module to be used in PET scanners dedicated to human brain and breast, and small animal studies. A new computer controlled gantry allows the system to be used for PET and SPECT applications. Silicon 8x8 detector arrays have been developed by CMRP and will be optically coupled scintillation crystals and readout using the VIKING tM hybrid preamplifier chip to form the basis of the new module Characterisation of the pixel photodiode array has been performed to check the uniformity of the response of the array. This characterisation has been done using a pulsed, near infra-red laser diode system and alpha particles

The effect of charged groups on hydrophilic monolithic stationary phases on their chromatographic properties.

Science.gov (United States)

Li, Haibin; Liu, Chusheng; Wang, Qiqin; Zhou, Haibo; Jiang, Zhengjin

2016-10-21

In order to investigate the effect of charged groups present in hydrophilic monolithic stationary phases on their chromatographic properties, three charged hydrophilic monomers, i.e. N,N-dimethyl-N-acryloyloxyethyl-N-(3-sulfopropyl)ammonium betaine (SPDA), [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETA), and 3-sulfopropyl acrylate potassium salt (SPA) were co-polymerized with the crosslinker N,N'-methylenebisacrylamide (MBA), respectively. The physicochemical properties of the three resulting charged hydrophilic monolithic columns were evaluated using scanning electron microscopy, ζ-potential analysis and micro-HPLC. High column efficiency was obtained on the three monolithic columns at a linear velocity of 1mm/s using thiourea as test compound. Comparative characterization of the three charged HILIC phases was then carried out using a set of model compounds, including nucleobases, nucleosides, benzoic acid derivatives, phenols, β-blockers and small peptides. Depending on the combination of stationary phase/mobile phase/solute, both hydrophilic interaction and other potential secondary interactions, including electrostatic interaction, hydrogen-bonding interaction, molecular shape selectivity, could contribute to the over-all retention of the analytes. Because of the strong electrostatic interaction provided by the quaternary ammonium groups in the poly (AETA-co-MBA) monolith, this cationic HILIC monolith exhibited the strongest retention for benzoic acid derivatives and small peptides with distorted peak shapes and the weakest retention for basic β-blockers. The sulfonyl groups on the poly (SPA-co-MBA) hydrophilic monolith could provide strong electrostatic attraction and hydrogen bonding for positively charged analytes and hydrogen-donor/acceptor containing analytes, respectively. Therefore, basic drugs, nucleobases and nucleotides exhibited the strongest retention on this anionic monolith. Because of the weak but distinct cation exchange properties of

Clinical usefulness of PET in the management of oral cancer. Comparison between FDG-PET and MET-PET

International Nuclear Information System (INIS)

Kitagawa, Yoshimasa; Saitoh, Masaaki; Nakamura, Mikiko

2007-01-01

Inductive chemoradiotherapy has played an important role in preserving organs and functions in patients with oral squamous cell carcinoma (SCC). To determine whether a reduced form of surgery should be performed after chemoradiotherapy, accurate evaluation of residual tumor cells is essential. We investigated the clinical value of positron emission tomography with 18 F labeled fluorodeoxyglucose (FDG-PET) in the management of oral SCCs. Forty-five patients underwent two FDG-PET studies, one prior to and one at 6 weeks after the chemoradiotherapy. Pretreatment FDG-PET was useful in predicting the response to treatment. Posttreatment FDG-PET could evaluate residual viable cells and prognosis. Organ preservation may be feasible based on PET evaluation. Hence FDG-PET is a valuable tool in the treatment of oral cancer. 11 C-Methionine (MET) is another promising tracer for PET that can be used to assess metabolic demand for amino acids in cancer cells. A MET-PET and FDG-PET study was performed during the same period to investigate diagnostic accuracy in 40 oral malignancies. Sensitivity and positive predictive value of MET-PET were 95% and 100%, respectively, and were comparable with those of FDG-PET. Further study is required to determine the diagnostic significance of MET-PET in evaluating response to chemoradiotherapy. (author)

Development of PET/MRI with insertable PET for simultaneous PET and MR imaging of human brain

International Nuclear Information System (INIS)

Jung, Jin Ho; Choi, Yong; Jung, Jiwoong; Kim, Sangsu; Lim, Hyun Keong; Im, Ki Chun; Oh, Chang Hyun; Park, Hyun-wook; Kim, Kyung Min; Kim, Jong Guk

2015-01-01

Purpose: The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain. Methods: The PET detector block was composed of a 4 × 4 matrix of detector modules, each consisting of a 4 × 4 array LYSO coupled to a 4 × 4 Geiger-mode avalanche photodiode (GAPD) array. The PET insert consisted of 18 detector blocks, circularly mounted on a custom-made plastic base to form a ring with an inner diameter of 390 mm and axial length of 60 mm. The PET gantry was shielded with gold-plated conductive fabric tapes with a thickness of 0.1 mm. The charge signals of PET detector transferred via 4 m long flat cables were fed into the position decoder circuit. The flat cables were shielded with a mesh-type aluminum sheet with a thickness of 0.24 mm. The position decoder circuit and field programmable gate array-embedded DAQ modules were enclosed in an aluminum box with a thickness of 10 mm and located at the rear of the MR bore inside the MRI room. A 3-T human MRI system with a Larmor frequency of 123.7 MHz and inner bore diameter of 60 cm was used as the PET/MRI hybrid system. A custom-made radio frequency (RF) coil with an inner diameter of 25 cm was fabricated. The PET was positioned between gradient and the RF coils. PET performance was measured outside and inside the MRI scanner using echo planar imaging, spin echo, turbo spin echo, and gradient echo sequences. MRI performance was also evaluated with and without the PET insert. The stability of the newly developed PET insert was evaluated and simultaneous PET and MR images of a brain phantom were acquired. Results: No significant degradation of the PET performance caused by MR was observed when the PET was operated using various MR imaging sequences. The signal-to-noise ratio of MR images was slightly degraded due to the PET insert installed inside the MR bore while the homogeneity was

Development of PET/MRI with insertable PET for simultaneous PET and MR imaging of human brain

Energy Technology Data Exchange (ETDEWEB)

Jung, Jin Ho; Choi, Yong, E-mail: ychoi.image@gmail.com; Jung, Jiwoong; Kim, Sangsu; Lim, Hyun Keong; Im, Ki Chun [Department of Electronic Engineering, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 121-742 (Korea, Republic of); Oh, Chang Hyun; Park, Hyun-wook [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Kyung Min; Kim, Jong Guk [Korea Institute of Radiological and Medical Science, 75 Nowon-ro, Nowon-gu, Seoul 139-709 (Korea, Republic of)

2015-05-15

Purpose: The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain. Methods: The PET detector block was composed of a 4 × 4 matrix of detector modules, each consisting of a 4 × 4 array LYSO coupled to a 4 × 4 Geiger-mode avalanche photodiode (GAPD) array. The PET insert consisted of 18 detector blocks, circularly mounted on a custom-made plastic base to form a ring with an inner diameter of 390 mm and axial length of 60 mm. The PET gantry was shielded with gold-plated conductive fabric tapes with a thickness of 0.1 mm. The charge signals of PET detector transferred via 4 m long flat cables were fed into the position decoder circuit. The flat cables were shielded with a mesh-type aluminum sheet with a thickness of 0.24 mm. The position decoder circuit and field programmable gate array-embedded DAQ modules were enclosed in an aluminum box with a thickness of 10 mm and located at the rear of the MR bore inside the MRI room. A 3-T human MRI system with a Larmor frequency of 123.7 MHz and inner bore diameter of 60 cm was used as the PET/MRI hybrid system. A custom-made radio frequency (RF) coil with an inner diameter of 25 cm was fabricated. The PET was positioned between gradient and the RF coils. PET performance was measured outside and inside the MRI scanner using echo planar imaging, spin echo, turbo spin echo, and gradient echo sequences. MRI performance was also evaluated with and without the PET insert. The stability of the newly developed PET insert was evaluated and simultaneous PET and MR images of a brain phantom were acquired. Results: No significant degradation of the PET performance caused by MR was observed when the PET was operated using various MR imaging sequences. The signal-to-noise ratio of MR images was slightly degraded due to the PET insert installed inside the MR bore while the homogeneity was

Fabrication of interfacial functionalized porous polymer monolith and its adsorption properties of copper ions

Energy Technology Data Exchange (ETDEWEB)

Han, Jiaxi; Du, Zhongjie; Zou, Wei; Li, Hangquan; Zhang, Chen, E-mail: zhangch@mail.buct.edu.cn

2014-07-15

Highlights: • Interface functionalized PGMA porous monolith was fabricated. • The adsorption capacity of Cu{sup 2+} was 35.3 mg/g. • The effects of porous structure on the adsorption of Cu{sup 2+} were studied. • The adsorption behaviors of porous monolith were studied. - Abstract: The interfacial functionalized poly (glycidyl methacrylate) (PGMA) porous monolith was fabricated and applied as a novel porous adsorbent for copper ions (Cu{sup 2+}). PGMA porous material with highly interconnected pore network was prepared by concentrated emulsion polymerization template. Then polyacrylic acid (PAA) was grafted onto the interface of the porous monolith by the reaction between the epoxy group on PGMA and a carboxyl group on PAA. Finally, the porous monolith was interfacial functionalized by rich amount of carboxyl groups and could adsorb copper ions effectively. The chemical structure and porous morphology of the porous monolith were measured by Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the effects of pore size distribution, pH value, co-existing ions, contacting time, and initial concentrations of copper ions on the adsorption capacity of the porous adsorbents were studied.

Evaluation of attenuation correction in cardiac PET using PET/MR.

Science.gov (United States)

Lau, Jeffrey M C; Laforest, R; Sotoudeh, H; Nie, X; Sharma, S; McConathy, J; Novak, E; Priatna, A; Gropler, R J; Woodard, P K

2017-06-01

Simultaneous acquisition Positron emission tomography/magnetic resonance (PET/MR) is a new technology that has potential as a tool both in research and clinical diagnosis. However, cardiac PET acquisition has not yet been validated using MR imaging for attenuation correction (AC). The goal of this study is to evaluate the feasibility of PET imaging using a standard 2-point Dixon volume interpolated breathhold examination (VIBE) MR sequence for AC. Evaluation was performed in both phantom and patient data. A chest phantom containing heart, lungs, and a lesion insert was scanned by both PET/MR and PET/CT. In addition, 30 patients underwent whole-body 18 F-fluorodeoxyglucose PET/CT followed by simultaneous cardiac PET/MR. Phantom study showed 3% reduction of activity values in the myocardium due to the non-inclusion of the phased array coil in the AC. In patient scans, average standardized uptake values (SUVs) obtained by PET/CT and PET/MR showed no significant difference (n = 30, 4.6 ± 3.5 vs 4.7 ± 2.8, P = 0.47). There was excellent per patient correlation between the values acquired by PET/CT and PET/MR (R 2  = 0.97). Myocardial SUVs PET imaging using MR for AC shows excellent correlation with myocardial SUVs obtained by standard PET/CT imaging. The 2-point Dixon VIBE MR technique can be used for AC in simultaneous PET/MR data acquisition.

Depth of interaction resolution measurements for a high resolution PET detector using position sensitive avalanche photodiodes

International Nuclear Information System (INIS)

Yang Yongfeng; Dokhale, Purushottam A; Silverman, Robert W; Shah, Kanai S; McClish, Mickel A; Farrell, Richard; Entine, Gerald; Cherry, Simon R

2006-01-01

We explore dual-ended read out of LSO arrays with two position sensitive avalanche photodiodes (PSAPDs) as a high resolution, high efficiency depth-encoding detector for PET applications. Flood histograms, energy resolution and depth of interaction (DOI) resolution were measured for unpolished LSO arrays with individual crystal sizes of 1.0, 1.3 and 1.5 mm, and for a polished LSO array with 1.3 mm pixels. The thickness of the crystal arrays was 20 mm. Good flood histograms were obtained for all four arrays, and crystals in all four arrays can be clearly resolved. Although the amplitude of each PSAPD signal decreases as the interaction depth moves further from the PSAPD, the sum of the two PSAPD signals is essentially constant with irradiation depth for all four arrays. The energy resolutions were similar for all four arrays, ranging from 14.7% to 15.4%. A DOI resolution of 3-4 mm (including the width of the irradiation band which is ∼2 mm) was obtained for all the unpolished arrays. The best DOI resolution was achieved with the unpolished 1 mm array (average 3.5 mm). The DOI resolution for the 1.3 mm and 1.5 mm unpolished arrays was 3.7 and 4.0 mm respectively. For the polished array, the DOI resolution was only 16.5 mm. Summing the DOI profiles across all crystals for the 1 mm array only degraded the DOI resolution from 3.5 mm to 3.9 mm, indicating that it may not be necessary to calibrate the DOI response separately for each crystal within an array. The DOI response of individual crystals in the array confirms this finding. These results provide a detailed characterization of the DOI response of these PSAPD-based PET detectors which will be important in the design and calibration of a PET scanner making use of this detector approach

Covalent attachment of polymeric monolith to polyether ether ketone (PEEK) tubing.

Science.gov (United States)

Lv, Chunguang; Heiter, Jaana; Haljasorg, Tõiv; Leito, Ivo

2016-08-17

A new method of reproducible preparation of vinylic polymeric monolithic columns with a key step of covalently anchoring the monolith to PEEK surface is described. In order to chemically attach the polymer monolith to the tube wall, methacrylate functional groups were introduced onto PEEK surface by a three-step procedure, including surface etching, surface reduction and surface methacryloylation. The chemical state of the modified tubing surface was characterized by attenuated total reflectance infrared (ATR-IR) spectroscopy. It was found that the etching step is the key to successfully modifying the PEEK tubing surface. Poly(styrene-co-divinylbenzene) monoliths were in situ synthesized by thermally initiated free radical copolymerization within the confines of surface-vinylized PEEK tubings of dimensions close to ones conventionally used in HPLC and UHPLC (1.6 mm internal diameter, 10.0-12.5 cm length). Adhesion test was done by measuring the operating pressure drop, which the prepared stationary phases can withstand. Good pressure resistance, up to 140 bar/10 cm (flow rate 0.5 mL min(-1), acetonitrile as a mobile phase), indicates strong bonding of monolith to the tubing wall. The monolithic material was proven to have a permeability of 1.7 × 10 (-14) m(2), applying acetonitrile-water 70:30 (v/v) as a mobile phase. The column performance was reproducible from column to column and was evaluated via the isocratic separation of a series of alkylbenzenes in the reversed-phase mode (acetonitrile-water 70:30, v/v). The numbers of plates per meter at optimal flow rate were found to be between 26 000 and 32 000 for the different analytes. Copyright © 2016 Elsevier B.V. All rights reserved.

Time of flight measurements based on FPGA using a breast dedicated PET

International Nuclear Information System (INIS)

Aguilar, A; García-Olcina, R; Martos, J; Soret, J; Torres, J; Benlloch, J M; González, A J; Sánchez, F

2014-01-01

In this work the implementation of a Time-to-Digital Converter (TDC) using a Nutt delay line FPGA-based and applied on a Positron Emission Tomography (PET) device is going to be presented in order to check the system's suitability for Time of Flight (TOF) measurements. In recent years, FPGAs have shown great advantages for precise time measurements in PET. The architecture employed for these measurements is described in detail. The system developed was tested on a dedicated breast PET prototype, composed of LYSO crystals and Positive Sensitive Photomultipliers (PSPMTs). Two distinct experiments were carried out for this purpose. In the first test, system linearity was evaluated in order to calibrate the time measurements, providing a linearity error of less than 2% and an average time resolution of 1.4 ns FWHM. The second set of measurements tested system resolution, resulting in a FWHM as good as 1.35 ns. The results suggest that the coincidence window for the current PET can be reduced in order to minimize the random events and thus, achieve better image quality

Highly crosslinked polymeric monoliths for reversed-phase capillary liquid chromatography of small molecules.

Science.gov (United States)

Liu, Kun; Tolley, H Dennis; Lee, Milton L

2012-03-02

Seven crosslinking monomers, i.e., 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA), neopentyl glycol dimethacrylate (NPGDMA), 1,5-pentanediol dimethacrylate (1,5-PDDMA), 1,6-hexanediol dimethacrylate (1,6-HDDMA), 1,10-decanediol dimethacrylate (1,10-DDDMA), and 1,12-dodecanediol dimethacrylate (1,12-DoDDMA), were used to synthesize highly cross-linked monolithic capillary columns for reversed-phase liquid chromatography (RPLC) of small molecules. Dodecanol and methanol were chosen as "good" and "poor" porogenic solvents, respectively, for these monoliths, and were investigated in detail to provide insight into the selection of porogen concentration using 1,12-DoDDMA. Isocratic elution of alkylbenzenes at a flow rate of 300 nL/min was conducted for all of the monoliths. Gradient elution of alkylbenzenes and alkylparabens provided high resolution separations. Optimized monoliths synthesized from all seven crosslinking monomers showed high permeability. Several of the monoliths demonstrated column efficiencies in excess of 50,000 plates/m. Monoliths with longer alkyl-bridging chains showed very little shrinking or swelling in solvents of different polarities. Column preparation was highly reproducible; the relative standard deviation (RSD) values (n=3) for run-to-run and column-to-column were less than 0.25% and 1.20%, respectively, based on retention times of alkylbenzenes. Copyright © 2012 Elsevier B.V. All rights reserved.

An ASIC implementation of digital front-end electronics for a high resolution PET scanner

International Nuclear Information System (INIS)

Newport, D.F.; Young, J.W.

1993-01-01

AN Application Specific Integrated Circuit (ASIC) has been designed and fabricated which implements many of the current functions found in the digital front-end electronics for a high resolution Positron Emission Tomography (PET) scanner. The ASIC performs crystal selection, energy qualification, time correction, and event counting functions for block technology high resolution PET scanners. Digitized x and y position, event energy, and time information are used by the ASIC to determine block crystal number, qualify the event based on energy, and correct the event time. In addition, event counting and block dead time calculations are performed for system dead time corrections. A loadable sequencer for controlling the analog front-end electronics is also implemented. The ASIC is implemented in a 37,000 gate, 1.0 micron CMOS gate-array and is capable of handling 4 million events/second while reducing parts count, cost, and power consumption over current board-level designs

18F-FDG PET and PET/CT in Burkitt's lymphoma

International Nuclear Information System (INIS)

Karantanis, Dimitrios; Durski, Jolanta M.; Lowe, Val J.; Nathan, Mark A.; Mullan, Brian P.; Georgiou, Evangelos; Johnston, Patrick B.; Wiseman, Gregory A.

2010-01-01

Objective: To explore the value of 18 F fluorodeoxy-glucose (FDG) positron emission tomography (PET) in Burkitt's lymphoma. Methods: All Burkitt's lymphoma patients referred for FDG PET or FDG PET/computed tomography (CT) exams at our institution from June 2003 to June 2006 were included. Selected patients were followed and clinical information was reviewed retrospectively. Results from FDG PET-PET/CT, as blindly reviewed by a consensus of two experienced readers, were compared with the status of the disease as determined by other laboratory, clinical and imaging exams and clinical follow-up. FDG PET-PET/CT results were classified as true positive or negative and false positive or negative. The degree of FDG uptake in the positive lesions was semiquantified as maximum standard uptake value (SUVmax). Results: Fifty-seven FDG PET-PET/CT exams were done in 15 patients. Seven exams were done for initial staging, 8 during and 14 after the completion of therapy, and 28 for disease surveillance. For nodal disease FDG PET-PET/CT was true positive in 8, true negative in 47 and false positive in 2 exams (sensitivity 100%, specificity 96%). For extranodal disease FDG PET-PET/CT was true positive in 6, true negative in 48 and false positive in 3 exams (sensitivity 100%, specificity 94%). The mean SUVmax for the positive nodal lesions was 15.7 (range 6.9-21.7, median 18.5) and for extranodal lesions was 14.2 (range 6.2-24.3, median 12.4). Conclusions: FDG PET-PET/CT is sensitive for the detection of viable disease in Burkitt's lymphoma. Affected areas demonstrated high degree of uptake that was reversible upon successful implementation of treatment.

Neutral Guest Capture via Lewis Acid/Base Molecular Square Receptors. X-ray Crystal Structure of {Cyclobis[(cis-(dppp)Pt(4-ethynylpyridyl)(2))(cis- (PEt(3))(2)Pt)]Ag(2)}(+6)(phenazine)- ((-)OSO(2)CF(3))(6).

Science.gov (United States)

Whiteford, Jeffery A.; Stang, Peter J.; Huang, Songping D.

1998-10-19

Interaction of {cyclobis[(cis-(dppp)Pt(4-ethynylpyridyl)(2))(cis-(L)M)]Ag(2)}(+6)((-)OSO(2)CF(3))(6), where M = Pt(II) or Pd(II) and L = dppp or 2PEt(3), with pyridine, pyrazine, phenazine, or 4,4'-dipyridyl ketone results in coordination Lewis acid/base host-guest assemblies via the "pi-tweezer effect" and mono or bis neutral guest coordination. All host-guest complexes are air stable microcrystalline solids with decomposition points greater than 170 degrees C. The homometallic Pt(II) receptors are more stable than the heteroaromatic Pt(II)-Pd(II) receptors toward heteratom-containing aromatic guests. The X-ray crystal structure of the host-guest complex {cyclobis[(cis-(dppp)Pt(4-ethynylpyridyl)(2))(cis-(PEt(3))(2)Pt)]Ag(2)}(+6)(phenazine)((-)OSO(2)CF(3))(6) is reported. The crystals with the empirical formula C(62)H(68)AgF(9)N(3)O(9)P(4)Pt(2)S(3) are triclinic P&onemacr; with a = 12.3919(8) Å, b = 17.160(1) Å, c = 18.932(1) Å, alpha = 90.892(1) degrees, beta = 97.127(1) degrees, gamma = 89.969(1) degrees, and Z = 2.

PET or PET-CT with cancer screening

International Nuclear Information System (INIS)

Wang Taisong; Zhao Jinhua; Song Jianhua

2007-01-01

At present, cancer screening remains a lot of debate in contemporary medical practice. Many constitutes have done a lot of experiments in cancer screening. The same version is that recommendations and decisions regarding cancer screening should be based on reliable data, not self- approbation. Now, some institutes advocate 18 F-FDG PET or 18 F-FDG PET-CT for cancer screening, here, discussed status quo, potential financial, radiation safety and statistical data in 18 F-FDG PET or 18 F-FDG PET- CT cancer screening. (authors)

PET / MRI vs. PET / CT. Indications Oncology

International Nuclear Information System (INIS)

Oliva González, Juan P.

2016-01-01

Hybrid techniques in Nuclear Medicine is currently a field in full development for diagnosis and treatment of various medical conditions. With the recent advent of PET / MRI much it speculated about whether or not it is superior to PET / CT especially in oncology. The Conference seeks to clarify this situation by dealing issues such as: State of the art technology PET / MRI; Indications Oncology; Some clinical cases. It concludes by explaining the oncological indications of both the real and current situation of the PET / MRI. (author)

Application of PET and PET/CT imaging for cancer screening

International Nuclear Information System (INIS)

Chen Yenkung; Hu Fenglan; Shen Yehyou; Liao, A.C.; Hung, T.Z.; Su, Chentau; Chen Liangkuang

2004-01-01

The aim of this study was to evaluate the potential application of 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) and PET/CT for cancer screening in asymptomatic individuals. Methods: The subjects consisted of 3631 physical check up examinees (1947 men, 1684 women; mean age ±SD, 52.1±8.2 y) with non-specific medical histories. Whole-body FDG PET (or PET/CT), ultrasound and tumor markers were performed on all patients. Focal hypermetabolic areas with intensities equal to or exceeding the level of FDG uptake in the brain and bladder were considered abnormal and interpreted as neoplasia. Follow-up periods were longer than one year. Results: Among the 3631 FDG PET (including 1687 PET/CT), ultrasound and tumor markers examinations, malignant tumors were discovered in 47 examinees (1.29%). PET findings were true-positive in 38 of the 47 cancers (80.9%). In addition, 32 of the 47 cancers were performed with the PET-CT scan. PET detected cancer lesions in 28 of the 32 examinees. However, the CT detected cancer lesions in only 15 of 32 examinees. Conclusion: The sensitivity of FDG PET in the detection of a wide variety of cancers is high. Most cancer can be detected with FDG PET in a resectable stage. CT of the PET/CT for localization and characteristics of the lesion shows an increased specificity of the PET scan. Using ultrasound and tumor markers may complement the PET scan in cancer screening for hepatic and urologic neoplasms. (authors)

PET/CT in lymphoma patients; PET-CT bei Lymphompatienten

Energy Technology Data Exchange (ETDEWEB)

Steinert, H.C. [Universitaetsspital Zuerich, Klinik und Poliklinik fuer Nuklearmedizin (Switzerland)

2004-11-01

First results of PET/CT in Hodgkin's disease (HD) and aggressive non-Hodgkin's lymphoma (NHL) are reported. From March 2001 to August 2004 822 PET/CT were performed at our clinic in lymphoma patients for primary staging, restaging after therapy, and diagnosis of recurrence. For coregistration non contrast-enhanced low-dose CT were used. Due to the exact anatomic localization of {sup 18}F-FDG accumulating lesions equivocal or false positive PET findings are avoided. In comparison to contrast enhanced CT, PET/CT has a higher sensitivity and specificity in patients with HD and aggressive NHL. Integration of PET/CT in treatment planning of radiation therapy optimizes the field volume. Even in the initial phase of clinical evaluation, PET/CT has proven useful in staging and restaging of lymphoma. The exact anatomic localization of the PET findings is essential for a precise report, for treatment planning of radiation therapy, and for planning surgical biopsy. (orig.) [German] Erste Ergebnisse der PET-CT bei Morbus Hodgkin (HD) und den aggressiven Non-Hodgkin-Lymphomen (NHL) werden beschrieben. Von Maerz 2001 bis August 2004 wurden 822 PET-CT bei Lymphompatienten zum primaeren Staging, zum Restaging nach Therapie und zur Rezidivdiagnostik an unserer Klinik durchgefuehrt. Fuer die Koregistration wurde ein Low-dose-CT ohne i.v.-Kontrastmittel verwendet. Durch die exakte anatomische Zuordnung der {sup 18}F-FDG aufnehmenden Laesionen wurden unklare oder falsch-positive PET-Befunde vermieden. Die PET-CT erzielte im Vergleich zur KM-verstaerkten CT eine hoehere Sensitivitaet und Spezifitaet bei Patienten mit HD und aggressiven NHL. Die Integration der PET-CT in die Planung der Strahlentherapie fuehrte zu einer Optimierung der Feldgrenzen. Die PET-CT hat sich bereits in der Phase der initialen klinischen Evaluation als wertvoll beim Staging und Restaging von Lymphomen erwiesen. Die exakte anatomische Zuordnung der PET-Informationen ist fuer eine sichere Befundung

III-Vs on Si for photonic applications-A monolithic approach

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhechao, E-mail: Zhechao.Wang@intec.ugent.be [School of ICT, Royal Institute of Technology, Electrum 229, Isafjordsgatan 22, 164 40 Kista (Sweden); Junesand, Carl; Metaferia, Wondwosen; Hu, Chen; Wosinski, Lech [School of ICT, Royal Institute of Technology, Electrum 229, Isafjordsgatan 22, 164 40 Kista (Sweden); Lourdudoss, Sebastian, E-mail: slo@kth.se [School of ICT, Royal Institute of Technology, Electrum 229, Isafjordsgatan 22, 164 40 Kista (Sweden)

2012-10-01

Highlights: Black-Right-Pointing-Pointer Monolithic evanescently coupled silicon laser (MECSL) structure treated. Black-Right-Pointing-Pointer Optical mode profiles and thermal resistivity of MECSL optimized by simulation. Black-Right-Pointing-Pointer MECSL through epitaxial lateral overgrowth (ELOG) of InP on Si exemplified. Black-Right-Pointing-Pointer Passive waveguide in MECSL also acts as the defect filtering mask in ELOG. Black-Right-Pointing-Pointer Growth of dislocation free thin InP layer on Si by ELOG for MECSL demonstrated. - Abstract: Epitaxial lateral overgrowth (ELOG) technology is demonstrated as a viable technology to realize monolithic integration of III-Vs on silicon. As an alternative to wafer-to-wafer bonding and die-to-wafer bonding, ELOG provides an attractive platform for fabricating discrete and integrated components in high volume at low cost. A possible route for monolithic integration of III-Vs on silicon for silicon photonics is exemplified by the case of a monolithic evanescently coupled silicon laser (MECSL) by combining InP on Si/SiO{sub 2} through ELOG. Passive waveguide in MECSL also acts as the defect filtering mask in ELOG. The structural design of a monolithic evanescently coupled silicon laser (MECSL) and its thermal resistivity are established through simulations. Material studies to realize the above laser through ELOG are undertaken by studying appropriate ELOG pattern designs to achieve InP on narrow regions of silicon. We show that defect-free InP can be obtained on SiO{sub 2} as the first step which paves the way for realizing active photonic devices on Si/SiO{sub 2} waveguides, e.g. an MECSL.

Do carotid MR surface coils affect PET quantification in PET/MR imaging?

International Nuclear Information System (INIS)

Willemink, Martin J; Eldib, Mootaz; Leiner, Tim; Fayad, Zahi A; Mani, Venkatesh

2015-01-01

To evaluate the effect of surface coils for carotid MR imaging on PET quantification in a clinical simultaneous whole-body PET/MR scanner. A cylindrical phantom was filled with a homogeneous 2L water-FDG mixture at a starting dose of 301.2MBq. Clinical PET/MR and PET/CT systems were used to acquire PET-data without a coil (reference standard) and with two carotid MRI coils (Siemens Special Purpose 8-Channel and Machnet 4-Channel Phased Array). PET-signal attenuation was evaluated with Osirix using 51 (PET/MR) and 37 (PET/CT) circular ROIs. Mean and maximum standardized uptake values (SUVs) were quantified for each ROI. Furthermore, SUVs of PET/MR and PET/CT were compared. For validation, a patient was scanned with an injected dose of 407.7MBq on both a PET/CT and a PET/MR system without a coil and with both coils. PET/MR underestimations were -2.2% (Siemens) and -7.8% (Machnet) for SUVmean, and -1.2% (Siemens) and -3.3% (Machnet) for SUVmax, respectively. For PET/CT, underestimations were -1.3% (Siemens) and -1.4% (Machnet) for SUVmean and -0.5% (both Siemens and Machnet) for SUVmax, respectively using no coil data as reference. Except for PET/CT SUVmax values all differences were significant. SUVs differed significantly between PET/MR and PET/CT with SUVmean values of 0.51-0.55 for PET/MR and 0.68-0.69 for PET/CT, respectively. The patient examination showed that median SUVmean values measured in the carotid arteries decreased from 0.97 without a coil to 0.96 (Siemens) and 0.88 (Machnet). Carotid surface coils do affect attenuation correction in both PET/MR and PET/CT imaging. Furthermore, SUVs differed significantly between PET/MR and PET/CT.

Porous polymer monolithic col

Directory of Open Access Journals (Sweden)

Lydia Terborg

2015-05-01

Full Text Available A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance. The amount of attached gold nanoparticles according to thermal gravimetric analysis was 44.8 wt.%. This value together with results of frontal elution enabled calculation of surface coverage with the alkanethiol and mercaptoalkanoic acid ligands. Interestingly, alkanethiols coverage in a range of 4.46–4.51 molecules/nm2 significantly exceeded that of mercaptoalkanoic acids with 2.39–2.45 molecules/nm2. The mixed mode character of these monolithic stationary phases was for the first time demonstrated in the separations of proteins that could be achieved in the same column using gradient elution conditions typical of reverse phase (using gradient of acetonitrile in water and ion exchange chromatographic modes (applying gradient of salt in water, respectively.

Solid State Characterizations of Long-Term Leached Cast Stone Monoliths

Energy Technology Data Exchange (ETDEWEB)

Asmussen, Robert M.; Pearce, Carolyn I.; Parker, Kent E.; Miller, Brian W.; Lee, Brady D.; Buck, Edgar C.; Washton, Nancy M.; Bowden, Mark E.; Lawter, Amanda R.; McElroy, Erin M.; Serne, R Jeffrey

2016-09-30

This report describes the results from the solid phase characterization of six Cast Stone monoliths from the extended leach tests recently reported on (Serne et al. 2016),that were selected for characterization using multiple state-of-the-art approaches. The Cast Stone samples investigated were leached for > 590 d in the EPA Method 1315 test then archived for > 390 d in their final leachate. After reporting the long term leach behavior of the monoliths (containing radioactive ⁹⁹Tc and stable ¹²⁷I spikes and for original Westsik et al. 2013 fabricated monoliths, ²³⁸U), it was suggested that physical changes to the waste forms and a depleting inventory of contaminants of potential concern may mean that effective diffusivity calculations past 63 d should not be used to accurately represent long-term waste form behavior. These novel investigations, in both length of leaching time and application of solid state techniques, provide an initial arsenal of techniques which can be utilized to perform such Cast Stone solid phase characterization work, which in turn can support upcoming performance assessment maintenance. The work was performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to characterize several properties of the long- term leached Cast Stone monolith samples.

A depth-encoding PET detector that uses light sharing and single-ended readout with silicon photomultipliers

Science.gov (United States)

Kuang, Zhonghua; Yang, Qian; Wang, Xiaohui; Fu, Xin; Ren, Ning; Sang, Ziru; Wu, San; Zheng, Yunfei; Zhang, Xianming; Hu, Zhanli; Du, Junwei; Liang, Dong; Liu, Xin; Zheng, Hairong; Yang, Yongfeng

2018-02-01

Detectors with depth-encoding capability and good timing resolution are required to develop high-performance whole-body or total-body PET scanners. In this work, depth-encoding PET detectors that use light sharing between two discrete crystals and single-ended readout with silicon photomultipliers (SiPMs) were manufactured and evaluated. The detectors consisted of two unpolished 3  ×  3  ×  20 mm3 LYSO crystals with different coupling materials between them and were read out by Hamamatsu 3  ×  3 mm2 SiPMs with one-to-one coupling. The ratio of the energy of one SiPM to the total energy of two SiPMs was used to measure the depth of interaction (DOI). Detectors with different coupling materials in-between the crystals were measured in the singles mode in an effort to obtain detectors that can provide good DOI resolution. The DOI resolution and energy resolution of three types of detector were measured and the timing resolution was measured for the detector with the best DOI and energy resolution. The optimum detector, with 5 mm optical glue, a 9 mm triangular ESR and a 6 mm rectangular ESR in-between the unpolished crystals, provides a DOI resolution of 2.65 mm, an energy resolution of 10.0% and a timing resolution of 427 ps for events of E  >  400 keV. The detectors simultaneously provide good DOI and timing resolution, and show great promise for the development of high-performance whole-body and total-body PET scanners.

Development of large-area silicon photomultiplier detectors for PET applications at FBK

Energy Technology Data Exchange (ETDEWEB)

Zorzi, Nicola, E-mail: zorzi@fbk.eu [Fondazione Bruno Kessler (FBK), Via Sommarive 18, I-38123 Trento Povo (Italy); Melchiorri, Mirko; Piazza, Alessandro; Piemonte, Claudio; Tarolli, Alessandro [Fondazione Bruno Kessler (FBK), Via Sommarive 18, I-38123 Trento Povo (Italy)

2011-04-21

This paper reports on the development of large-area silicon photomultiplier (SiPM) detectors specifically designed for positron emission tomography (PET) instruments. The sensors under study are monolithic arrays of two different types: a 2x2 array of {approx}4x4 mm{sup 2} elements and an 8x8 array of 1.5x1.5 mm{sup 2} pixels. These devices are characterized at wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. The tests allowed selection of functioning devices and evaluation of the uniformity of basic parameters. Results of the electrical characterization are reported showing that acceptable values of yield together with rather uniform distribution of parameters have been obtained. Reliability of produced SiPMs has been proved by long-term accelerated stress tests.

Development of large-area silicon photomultiplier detectors for PET applications at FBK

International Nuclear Information System (INIS)

Zorzi, Nicola; Melchiorri, Mirko; Piazza, Alessandro; Piemonte, Claudio; Tarolli, Alessandro

2011-01-01

This paper reports on the development of large-area silicon photomultiplier (SiPM) detectors specifically designed for positron emission tomography (PET) instruments. The sensors under study are monolithic arrays of two different types: a 2x2 array of ∼4x4 mm 2 elements and an 8x8 array of 1.5x1.5 mm 2 pixels. These devices are characterized at wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. The tests allowed selection of functioning devices and evaluation of the uniformity of basic parameters. Results of the electrical characterization are reported showing that acceptable values of yield together with rather uniform distribution of parameters have been obtained. Reliability of produced SiPMs has been proved by long-term accelerated stress tests.

Evaluation of the PET component of simultaneous [18F]choline PET/MRI in prostate cancer: comparison with [18F]choline PET/CT

International Nuclear Information System (INIS)

Wetter, Axel; Lipponer, Christine; Nensa, Felix; Altenbernd, Jens-Christian; Schlosser, Thomas; Lauenstein, Thomas; Heusch, Philipp; Ruebben, Herbert; Bockisch, Andreas; Poeppel, Thorsten; Nagarajah, James

2014-01-01

The aim of this study was to evaluate the positron emission tomography (PET) component of [ 18 F]choline PET/MRI and compare it with the PET component of [ 18 F]choline PET/CT in patients with histologically proven prostate cancer and suspected recurrent prostate cancer. Thirty-six patients were examined with simultaneous [ 18 F]choline PET/MRI following combined [ 18 F]choline PET/CT. Fifty-eight PET-positive lesions in PET/CT and PET/MRI were evaluated by measuring the maximum and mean standardized uptake values (SUV max and SUV mean ) using volume of interest (VOI) analysis. A scoring system was applied to determine the quality of the PET images of both PET/CT and PET/MRI. Agreement between PET/CT and PET/MRI regarding SUV max and SUV mean was tested using Pearson's product-moment correlation and Bland-Altman analysis. All PET-positive lesions that were visible on PET/CT were also detectable on PET/MRI. The quality of the PET images was comparable in both groups. Median SUV max and SUV mean of all lesions were significantly lower in PET/MRI than in PET/CT (5.2 vs 6.1, p max of PET/CT and PET/MRI (R = 0.86, p mean of PET/CT and PET/MRI (R = 0.81, p max of PET/CT vs PET/MRI and -1.12 to +2.23 between SUV mean of PET/CT vs PET/MRI. PET image quality of PET/MRI was comparable to that of PET/CT. A highly significant correlation between SUV max and SUV mean was found. Both SUV max and SUV mean were significantly lower in [ 18 F]choline PET/MRI than in [ 18 F]choline PET/CT. Differences of SUV max and SUV mean might be caused by different techniques of attenuation correction. Furthermore, differences in biodistribution and biokinetics of [ 18 F]choline between the subsequent examinations and in the respective organ systems have to be taken into account. (orig.)

Fabrication and Characterisation of Low-noise Monolithic Mode-locked Lasers

DEFF Research Database (Denmark)

Larsson, David

2007-01-01

This thesis deals with the fabrication and characterisation of monolithic semiconductor mode-locked lasers for use in optical communication systems. Other foreseeable applications may be as sources in microwave photonics and optical sampling. The thesis also deals with the design and fabrication...... of intracavity monolithically integrated filters. The common dnominator among the diffrent parts of the thesis is how to achieve and measure the lowest possible noise. Achieving low noise has been pinpointed as one of the most important and difficult challenges for semiconductor mode-locked lasers. The main...... result of this thesis are a fabrication process of a monolithic and deeply etched distributed Bragg reflector and a characterisation system for measurement of quantum limitid timing noise at high repetition rates. The Bragg reflector is a key component in achieving transform limited pulses with low noise...

Recent progress in low-temperature-process monolithic three dimension technology

Science.gov (United States)

Yang, Chih-Chao; Hsieh, Tung-Ying; Huang, Wen-Hsien; Shen, Chang-Hong; Shieh, Jia-Min; Yeh, Wen-Kuan; Wu, Meng-Chyi

2018-04-01

Monolithic three-dimension (3D) integration is an ultimate alternative method of fabricating high density, high performance, and multi-functional integrated circuits. It offers the promise of being a new approach to increase system performance. How to manage the thermal impact of multi-tiered processes, such as dopant activation, source/drain silicidation, and channel formation, and to prevent the degradation of pre-existing devices/circuits become key challenges. In this paper, we provide updates on several important monolithic 3D works, particularly in sequentially stackable channels, and our recent achievements in monolithic 3D integrated circuit (3D-IC). These results indicate that the advanced 3D architecture with novel design tools enables ultrahigh-density stackable circuits to have superior performance and low power consumption for future artificial intelligence (AI) and internet of things (IoTs) application.

Luminescent and laser properties of Yb Er:GdCa4O(BO3)3: a new crystal for eye-safe 1.5-μm lasers

Science.gov (United States)

Denker, B.; Galagan, B.; Ivleva, L.; Osiko, V.; Sverchkov, S.; Voronina, I.; Hellstrom, J. E.; Karlsson, G.; Laurell, F.

2004-09-01

We present for the first time 1.5-μm laser emission in Yb Er:GdCa4O(BO3)3 (GdCOB). The crystals were grown by the Czochralski method from platinum crucibles. Spectroscopic and laser tests of the crystals are described. A continuous-wave output power of 80 mW was achieved in a monolithic microchip cavity under laser-diode pumping.

Monolithic fiber optic sensor assembly

Science.gov (United States)

Sanders, Scott

2015-02-10

A remote sensor element for spectrographic measurements employs a monolithic assembly of one or two fiber optics to two optical elements separated by a supporting structure to allow the flow of gases or particulates therebetween. In a preferred embodiment, the sensor element components are fused ceramic to resist high temperatures and failure from large temperature changes.

Towards a Technique for Extracting Microservices from Monolithic Enterprise Systems

OpenAIRE

Levcovitz, Alessandra; Terra, Ricardo; Valente, Marco Tulio

2016-01-01

The idea behind microservices architecture is to develop a single large, complex application as a suite of small, cohesive, independent services. On the other way, monolithic systems get larger over the time, deviating from the intended architecture, and becoming risky and expensive to evolve. This paper describes a technique to identify and define microservices on monolithic enterprise systems. As the major contribution, our evaluation shows that our approach was able to identify relevant ca...

[Principles of PET].

Science.gov (United States)

Beuthien-Baumann, B

2018-05-01

Positron emission tomography (PET) is a procedure in nuclear medicine, which is applied predominantly in oncological diagnostics. In the form of modern hybrid machines, such as PET computed tomography (PET/CT) and PET magnetic resonance imaging (PET/MRI) it has found wide acceptance and availability. The PET procedure is more than just another imaging technique, but a functional method with the capability for quantification in addition to the distribution pattern of the radiopharmaceutical, the results of which are used for therapeutic decisions. A profound knowledge of the principles of PET including the correct indications, patient preparation, and possible artifacts is mandatory for the correct interpretation of PET results.

Evaluation of Dixon Sequence on Hybrid PET/MR Compared with Contrast-Enhanced PET/CT for PET-Positive Lesions

International Nuclear Information System (INIS)

Jeong, Ju Hye; Cho, Ihn Ho; Kong, Eun Jung; Chun, Kyung Ah

2014-01-01

Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases. Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85±13 min after 18 F-FDG injection of 403± 45 MBq) and then (125±19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison. Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64± 0.70; in-phase, 1.29±1.01; opposed-phase, 1.29±1.15; water-weighted, 1.71±1.07; fat weighted, 0.56±1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63±1.62; SUVmax, 4.30±2.88) and contrast-enhanced PET

Evaluation of Dixon Sequence on Hybrid PET/MR Compared with Contrast-Enhanced PET/CT for PET-Positive Lesions

Energy Technology Data Exchange (ETDEWEB)

Jeong, Ju Hye; Cho, Ihn Ho; Kong, Eun Jung; Chun, Kyung Ah [Yeungnam Univ. Hospital, Daegu (Korea, Republic of)

2014-03-15

Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases. Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85±13 min after {sup 18}F-FDG injection of 403± 45 MBq) and then (125±19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison. Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64± 0.70; in-phase, 1.29±1.01; opposed-phase, 1.29±1.15; water-weighted, 1.71±1.07; fat weighted, 0.56±1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63±1.62; SUVmax, 4.30±2.88) and contrast

Evaluation of a timing integrated circuit architecture for continuous crystal and SiPM based PET systems

OpenAIRE

Monzó Ferrer, José María; Ros García, Ana; Herrero Bosch, Vicente; Perino Vicentini, Ivan Virgilio; Aliaga Varea, Ramón José; Gadea Gironés, Rafael; Colom Palero, Ricardo José

2013-01-01

Improving timing resolution in positron emission tomography (PET), thus having fine time information of the detected pulses, is important to increase the reconstructed images signal to noise ratio (SNR) [1]. In the present work, an integrated circuit topology for time extraction of the incoming pulses is evaluated. An accurate simulation including the detector physics and the electronics with different configurations has been developed. The selected architecture is intended for a PET sys...

The origin and reduction of spurious extrahepatic counts observed in 90Y non-TOF PET imaging post radioembolization

Science.gov (United States)

Walrand, Stephan; Hesse, Michel; Jamar, François; Lhommel, Renaud

2018-04-01

Our literature survey revealed a physical effect unknown to the nuclear medicine community, i.e. internal bremsstrahlung emission, and also the existence of long energy resolution tails in crystal scintillation. None of these effects has ever been modelled in PET Monte Carlo (MC) simulations. This study investigates whether these two effects could be at the origin of two unexplained observations in 90Y imaging by PET: the increasing tails in the radial profile of true coincidences, and the presence of spurious extrahepatic counts post radioembolization in non-TOF PET and their absence in TOF PET. These spurious extrahepatic counts hamper the microsphere delivery check in liver radioembolization. An acquisition of a 32P vial was performed on a GSO PET system. This is the ideal setup to study the impact of bremsstrahlung x-rays on the true coincidence rate when no positron emission and no crystal radioactivity are present. A MC simulation of the acquisition was performed using Gate-Geant4. MC simulations of non-TOF PET and TOF-PET imaging of a synthetic 90Y human liver radioembolization phantom were also performed. Internal bremsstrahlung and long energy resolution tails inclusion in MC simulations quantitatively predict the increasing tails in the radial profile. In addition, internal bremsstrahlung explains the discrepancy previously observed in bremsstrahlung SPECT between the measure of the 90Y bremsstrahlung spectrum and its simulation with Gate-Geant4. However the spurious extrahepatic counts in non-TOF PET mainly result from the failure of conventional random correction methods in such low count rate studies and poor robustness versus emission-transmission inconsistency. A novel proposed random correction method succeeds in cleaning the spurious extrahepatic counts in non-TOF PET. Two physical effects not considered up to now in nuclear medicine were identified to be at the origin of the unusual 90Y true coincidences radial profile. TOF reconstruction removing

Observations on dual-ended readout of 100 mm long LYSO crystals

International Nuclear Information System (INIS)

Ur-Rehman, Fazal; McIntosh, Bryan; Goertzen, Andrew L.

2011-01-01

We are investigating using dual-ended readout of axially oriented long thin scintillator crystals in detectors for a compact geometry, small ring diameter animal PET system. The axial position of interaction is determined from the light sharing between two photodetectors at opposite ends of the crystal. We examine the light output, energy resolution and axial spatial resolution of 1.5-5x2x100 mm 3 polished LYSO crystals by irradiating with an electronically collimated beam of 511 keV photons oriented perpendicular to the long axis and read out at either end by position sensitive photomultiplier tubes (PSPMTs). Three reflector materials, namely Teflon, 3 M enhanced specular reflector (ESR) and black paint are examined for the 2x2x100 mm 3 crystal size. The light output increases and energy resolution improves with the crystal cross-section. Generally, the spatial resolution worsens with increase in crystal cross-section. For the 2x2x100 mm 3 crystal size, the mean energy resolutions of the photopeak over the nine irradiation positions were 14.4±0.4%, 16.0±1.2% and 28.3±2.1% with mean spatial resolutions of 7.0±1.0, 9.4±3.3 and 26.0±5.0 mm using ESR, Teflon and black paint, respectively. ESR reflector gave the best light output, energy and axial spatial resolutions. These characterization results of PSPMT-based dual-ended long LYSO crystals will be useful in the design of detector modules for a highly compact geometry preclinical PET system using this detector technology.

Lung PET scan

Science.gov (United States)

... Chest PET scan; Lung positron emission tomography; PET - chest; PET - lung; PET - tumor imaging; ... Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging . 6th ed. Philadelphia, ...

Stable polarization short pulse passively Q-switched monolithic microchip laser with [110] cut Cr4+:YAG

International Nuclear Information System (INIS)

Wang, Y; Gong, M; Yan, P; Huang, L; Li, D

2009-01-01

A monolithic Nd:YAG microchip laser with [110] cut Cr 4+ :YAG is presented. The output beam is linearly polarized with polarization ratio higher than 100:1. The polarization direction is stable, independent of pump power, crystal temperature, LD temperature. In single longitudinal mode operation, stable 259 ps pulses at 2.5 kHz with 82 kW peak power and diffraction limited beam mode are output. With a simple and compact one-pass Nd:YVO 4 amplifier, 144 kW peak power is achieved. Single longitudinal and fundamental transverse mode is kept after passing through the amplifier stage. The microchip laser can be operated in two longitudinal modes with two sets of output pulses by increasing the pump power

CERN crystals used in medical imaging

CERN Multimedia

Maximilien Brice

2004-01-01

This crystal is a type of material known as a scintillator. When a high energy charged particle or photon passes through a scintillator it glows. These materials are widely used in particle physics for particle detection, but their uses are being realized in further fields, such as Positron Emission Tomography (PET), an area of medical imaging that monitors the regions of energy use in the body.

Antagonist wear of monolithic zirconia crowns after 2 years.

Science.gov (United States)

Lohbauer, Ulrich; Reich, Sven

2017-05-01

The aim of this study was to evaluate the amount of wear on the antagonist occlusal surfaces of clinically placed monolithic zirconia premolar and molar crowns (LAVA Plus, 3M ESPE). Fourteen in situ monolithic zirconia crowns and their opposing antagonists (n = 26) are the subject of an ongoing clinical trial and have been clinically examined at baseline and after 24 months. Silicone impressions were taken and epoxy replicas produced for qualitative SEM analysis and quantitative analysis using optical profilometry. Based on the baseline replicas, the follow-up situation has been scanned and digitally matched with the initial topography in order to calculate the mean volume loss (in mm 3 ) as well as the mean maximum vertical loss (in mm) after 2 years in service. The mean volume loss for enamel antagonist contacts (n = 7) was measured to 0.361 mm 3 and the mean of the maximum vertical loss to 0.204 mm. The mean volume loss for pure ceramic contacts (n = 10) was measured to 0.333 mm 3 and the mean of the maximum vertical loss to 0.145 mm. The wear rates on enamel contacts were not significantly different from those measured on ceramic antagonists. Based on the limitations of this study, it can be concluded for the monolithic zirconia material LAVA Plus that the measured wear rates are in consensus with other in vivo studies on ceramic restorations. Further, that no significant difference was found between natural enamel antagonists and ceramic restorations as antagonists. The monolithic zirconia restorations do not seem to be affected by wear within the first 2 years. The monolithic zirconia crowns (LAVA Plus) show acceptable antagonist wear rates after 2 years in situ, regardless of natural enamel or ceramics as antagonist materials.

Simultaneous PET/MRI with 13C magnetic resonance spectroscopic imaging (hyperPET): phantom-based evaluation of PET quantification

DEFF Research Database (Denmark)

Hansen, Adam E.; Andersen, Flemming L.; Henriksen, Sarah T.

2016-01-01

Background: Integrated PET/MRI with hyperpolarized 13C magnetic resonance spectroscopic imaging (13C-MRSI) offers simultaneous, dual-modality metabolic imaging. A prerequisite for the use of simultaneous imaging is the absence of interference between the two modalities. This has been documented...... for a clinical whole-body system using simultaneous 1 H-MRI and PET but never for 13C-MRSI and PET. Here, the feasibility of simultaneous PET and 13C-MRSI as well as hyperpolarized 13C-MRSI in an integrated whole-body PET/MRI hybrid scanner is evaluated using phantom experiments. Methods: Combined PET and 13C......-MRSI phantoms including a NEMA [18F]-FDG phantom, 13C-acetate and 13C-urea sources, and hyperpolarized 13C-pyruvate were imaged repeatedly with PET and/or 13C-MRSI. Measurements evaluated for interference effects included PET activity values in the largest sphere and a background region; total number of PET...

Positron Emission Tomography (PET)

International Nuclear Information System (INIS)

Welch, M.J.

1990-01-01

Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs

Positron Emission Tomography (PET)

Science.gov (United States)

Welch, M. J.

1990-01-01

Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET.

Positron Emission Tomography (PET)

Energy Technology Data Exchange (ETDEWEB)

Welch, M.J.

1990-01-01

Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

A monolithic integrated photonic microwave filter

Science.gov (United States)

Fandiño, Javier S.; Muñoz, Pascual; Doménech, David; Capmany, José

2017-02-01

Meeting the increasing demand for capacity in wireless networks requires the harnessing of higher regions in the radiofrequency spectrum, reducing cell size, as well as more compact, agile and power-efficient base stations that are capable of smoothly interfacing the radio and fibre segments. Fully functional microwave photonic chips are promising candidates in attempts to meet these goals. In recent years, many integrated microwave photonic chips have been reported in different technologies. To the best of our knowledge, none has monolithically integrated all the main active and passive optoelectronic components. Here, we report the first demonstration of a tunable microwave photonics filter that is monolithically integrated into an indium phosphide chip. The reconfigurable radiofrequency photonic filter includes all the necessary elements (for example, lasers, modulators and photodetectors), and its response can be tuned by means of control electric currents. This is an important step in demonstrating the feasibility of integrated and programmable microwave photonic processors.

Monolithically integrated 8-channel WDM reflective modulator

NARCIS (Netherlands)

Stopinski, S.T.; Malinowski, M.; Piramidowicz, R.; Smit, M.K.; Leijtens, X.J.M.

2013-01-01

In this work the design and characterization of a monolithically integrated photonic circuit acting as a reflective modulator for eight WDM channels is presented. The chip was designed and fabricated in a generic integration technology

Evaluation of a timing integrated circuit architecture for continuous crystal and SiPM based PET systems

International Nuclear Information System (INIS)

Monzo, J M; Ros, A; Herrero-Bosch, V; Perino, I V; Aliaga, R J; Gadea-Girones, R; Colom-Palero, R J

2013-01-01

Improving timing resolution in positron emission tomography (PET), thus having fine time information of the detected pulses, is important to increase the reconstructed images signal to noise ratio (SNR) [1]. In the present work, an integrated circuit topology for time extraction of the incoming pulses is evaluated. An accurate simulation including the detector physics and the electronics with different configurations has been developed. The selected architecture is intended for a PET system based on a continuous scintillation crystal attached to a SiPM array. The integrated circuit extracts the time stamp from the first few photons generated when the gamma-ray interacts with the scintillator, thus obtaining the best time resolution. To get the time stamp from the detected pulses, a time to digital converter (TDC) array based architecture has been proposed as in [2] or [3]. The TDC input stage uses a current comparator to transform the analog signal into a digital signal. Individually configurable trigger levels allow us to avoid false triggers due to signal noise. Using a TDC per SiPM configuration results in a very area consuming integrated circuit. One solution to this problem is to join several SiPM outputs to one TDC. This reduces the number of TDCs but, on the other hand, the first photons will be more difficult to be detected. For this reason, it is important to simulate how the time resolution is degraded when the number of TDCs is reduced. Following this criteria, the best configuration will be selected considering the trade-off between achievable time resolution and the cost per chip. A simulation is presented that uses Geant4 for simulation of the physics process and, for the electronic blocks, spice and Matlab. The Geant4 stage simulates the gamma-ray interaction with the scintillator, the photon shower generation and the first stages of the SiPM. The electronics simulation includes an electrical model of the SiPM array and all the integrated circuitry

Monolithic Integrated Ceramic Waveguide Filters

OpenAIRE

Hunter, IC; Sandhu, MY

2014-01-01

Design techniques for a new class of integrated monolithic high permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled TEM filters with the same unloaded Q-Factor. Designs for both chebyshev and asymmetric generalized chebyshev filter are presented, with experimental results for an 1800 MHz chebyshev filter showing excellent agreement with theory.

Indeterminate findings on oncologic PET/CT: What difference dose PET/MRI make?

Energy Technology Data Exchange (ETDEWEB)

Fraum, Tyler J.; Fowler, Kathryn J.; McConathy, Jonathan; Dehdashti, Farokh [Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis (United States)

2016-12-15

Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-[{sup 18}F]fluoro-D-glucose (FDG) has become the standard of care for the initial staging and subsequent treatment response assessment of many different malignancies. Despite this success, PET/CT is often supplemented by MRI to improve assessment of local tumor invasion and to facilitate detection of lesions in organs with high background FDG uptake. Consequently, PET/MRI has the potential to expand the clinical value of PET examinations by increasing reader certainty and reducing the need for subsequent imaging. This study evaluates the ability of FDG-PET/MRI to clarify findings initially deemed indeterminate on clinical FDG-PET/CT studies. A total of 190 oncology patients underwent whole-body PET/CT, immediately followed by PET/MRI utilizing the same FDG administration. Each PET/CT was interpreted by our institution's nuclear medicine service as a standard-of-care clinical examination. Review of these PET/CT reports identified 31 patients (16 %) with indeterminate findings. Two readers evaluated all 31 PET/CT studies, followed by the corresponding PET/MRI studies. A consensus was reached for each case, and changes in interpretation directly resulting from PET/MRI review were recorded. Interpretations were then correlated with follow-up imaging, pathology results, and other diagnostic studies. In 18 of 31 cases with indeterminate findings on PET/CT, PET/MRI resulted in a more definitive interpretation by facilitating the differentiation of infection/inflammation from malignancy (15/18), the accurate localization of FDG-avid lesions (2/18), and the characterization of incidental non-FDG-avid solid organ lesions (1/18). Explanations for improved reader certainty with PET/MRI included the superior soft tissue contrast of MRI and the ability to assess cellular density with diffusion-weighted imaging. The majority (12/18) of such cases had an appropriate standard of reference; in all 12 cases

Indeterminate findings on oncologic PET/CT: What difference dose PET/MRI make?

International Nuclear Information System (INIS)

Fraum, Tyler J.; Fowler, Kathryn J.; McConathy, Jonathan; Dehdashti, Farokh

2016-01-01

Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-["1"8F]fluoro-D-glucose (FDG) has become the standard of care for the initial staging and subsequent treatment response assessment of many different malignancies. Despite this success, PET/CT is often supplemented by MRI to improve assessment of local tumor invasion and to facilitate detection of lesions in organs with high background FDG uptake. Consequently, PET/MRI has the potential to expand the clinical value of PET examinations by increasing reader certainty and reducing the need for subsequent imaging. This study evaluates the ability of FDG-PET/MRI to clarify findings initially deemed indeterminate on clinical FDG-PET/CT studies. A total of 190 oncology patients underwent whole-body PET/CT, immediately followed by PET/MRI utilizing the same FDG administration. Each PET/CT was interpreted by our institution's nuclear medicine service as a standard-of-care clinical examination. Review of these PET/CT reports identified 31 patients (16 %) with indeterminate findings. Two readers evaluated all 31 PET/CT studies, followed by the corresponding PET/MRI studies. A consensus was reached for each case, and changes in interpretation directly resulting from PET/MRI review were recorded. Interpretations were then correlated with follow-up imaging, pathology results, and other diagnostic studies. In 18 of 31 cases with indeterminate findings on PET/CT, PET/MRI resulted in a more definitive interpretation by facilitating the differentiation of infection/inflammation from malignancy (15/18), the accurate localization of FDG-avid lesions (2/18), and the characterization of incidental non-FDG-avid solid organ lesions (1/18). Explanations for improved reader certainty with PET/MRI included the superior soft tissue contrast of MRI and the ability to assess cellular density with diffusion-weighted imaging. The majority (12/18) of such cases had an appropriate standard of reference; in all 12 cases, the

PET and PET/CT in tumour of undetermined origin; PET y PET/CT en tumor de origen indeterminado

Energy Technology Data Exchange (ETDEWEB)

Garcia O, J R [Nuclear Medicine and Molecular Imaging, PET/CT, Centro Medico ABC, Mexico D.F. (Mexico)

2007-07-01

In this presentation the following conclusions were obtained regarding the use of PET and PET/CT in patient with cancer of unknown primary: 1. Detection of the primary one in 1/3 at 1/2 of patient. 2. It detects metastases in other places in 50%. 3. It changes the initial therapy planned in 1/3 at 1/2 of patient. 4. Useful in initial phases of protocol study to limit the other procedures. After standard evaluation. Before advanced protocol. 5. PET/CT study increases the % of primary detection, although in a non significant way vs. PET. 6. They are required more studies to value their utility to a more objective manner. (Author)

Environmentally Benign Production of Stretchable and Robust Superhydrophobic Silicone Monoliths.

Science.gov (United States)

Davis, Alexander; Surdo, Salvatore; Caputo, Gianvito; Bayer, Ilker S; Athanassiou, Athanassia

2018-01-24

Superhydrophobic materials hold an enormous potential in sectors as important as aerospace, food industries, or biomedicine. Despite this great promise, the lack of environmentally friendly production methods and limited robustness remain the two most pertinent barriers to the scalability, large-area production, and widespread use of superhydrophobic materials. In this work, highly robust superhydrophobic silicone monoliths are produced through a scalable and environmentally friendly emulsion technique. It is first found that stable and surfactantless water-in-polydimethylsiloxane (PDMS) emulsions can be formed through mechanical mixing. Increasing the internal phase fraction of the precursor emulsion is found to increase porosity and microtexture of the final monoliths, rendering them superhydrophobic. Silica nanoparticles can also be dispersed in the aqueous internal phase to create micro/nanotextured monoliths, giving further improvements in superhydrophobicity. Due to the elastomeric nature of PDMS, superhydrophobicity can be maintained even while the material is mechanically strained or compressed. In addition, because of their self-similarity, the monoliths show outstanding robustness to knife-scratch, tape-peel, and finger-wipe tests, as well as rigorous sandpaper abrasion. Superhydrophobicity was also unchanged when exposed to adverse environmental conditions including corrosive solutions, UV light, extreme temperatures, and high-energy droplet impact. Finally, important properties for eventual adoption in real-world applications including self-cleaning, stain-repellence, and blood-repellence are demonstrated.

Optical properties of pre-colored dental monolithic zirconia ceramics.

Science.gov (United States)

Kim, Hee-Kyung; Kim, Sung-Hun

2016-12-01

The purposes of this study were to evaluate the optical properties of recently marketed pre-colored monolithic zirconia ceramics and to compare with those of veneered zirconia and lithium disilicate glass ceramics. Various shades of pre-colored monolithic zirconia, veneered zirconia, and lithium disilicate glass ceramic specimens were tested (17.0×17.0×1.5mm, n=5). CIELab color coordinates were obtained against white, black, and grey backgrounds with a spectrophotometer. Color differences of the specimen pairs were calculated by using the CIEDE2000 (ΔE 00 ) formula. The translucency parameter (TP) was derived from ΔE 00 of the specimen against a white and a black background. X-ray diffraction was used to determine the crystalline phases of monolithic zirconia specimens. Data were analyzed with 1-way ANOVA, Scheffé post hoc, and Pearson correlation testing (α=0.05). For different shades of the same ceramic brand, there were significant differences in L * , a * , b * , and TP values in most ceramic brands. With the same nominal shade (A2), statistically significant differences were observed in L * , a * , b * , and TP values among different ceramic brands and systems (Pceramics of the corresponding nominal shades ranged beyond the acceptability threshold. Due to the high L * values and low a * and b * values, pre-colored monolithic zirconia ceramics can be used with additional staining to match neighboring restorations or natural teeth. Due to their high value and low chroma, unacceptable color mismatch with adjacent ceramic restorations might be expected. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous PET/MRI with (13)C magnetic resonance spectroscopic imaging (hyperPET): phantom-based evaluation of PET quantification.

Science.gov (United States)

Hansen, Adam E; Andersen, Flemming L; Henriksen, Sarah T; Vignaud, Alexandre; Ardenkjaer-Larsen, Jan H; Højgaard, Liselotte; Kjaer, Andreas; Klausen, Thomas L

2016-12-01

Integrated PET/MRI with hyperpolarized (13)C magnetic resonance spectroscopic imaging ((13)C-MRSI) offers simultaneous, dual-modality metabolic imaging. A prerequisite for the use of simultaneous imaging is the absence of interference between the two modalities. This has been documented for a clinical whole-body system using simultaneous (1)H-MRI and PET but never for (13)C-MRSI and PET. Here, the feasibility of simultaneous PET and (13)C-MRSI as well as hyperpolarized (13)C-MRSI in an integrated whole-body PET/MRI hybrid scanner is evaluated using phantom experiments. Combined PET and (13)C-MRSI phantoms including a NEMA [(18)F]-FDG phantom, (13)C-acetate and (13)C-urea sources, and hyperpolarized (13)C-pyruvate were imaged repeatedly with PET and/or (13)C-MRSI. Measurements evaluated for interference effects included PET activity values in the largest sphere and a background region; total number of PET trues; and (13)C-MRSI signal-to-noise ratio (SNR) for urea and acetate phantoms. Differences between measurement conditions were evaluated using t tests. PET and (13)C-MRSI data acquisition could be performed simultaneously without any discernible artifacts. The average difference in PET activity between acquisitions with and without simultaneous (13)C-MRSI was 0.83 (largest sphere) and -0.76 % (background). The average difference in net trues was -0.01 %. The average difference in (13)C-MRSI SNR between acquisitions with and without simultaneous PET ranged from -2.28 to 1.21 % for all phantoms and measurement conditions. No differences were significant. The system was capable of (13)C-MRSI of hyperpolarized (13)C-pyruvate. Simultaneous PET and (13)C-MRSI in an integrated whole-body PET/MRI hybrid scanner is feasible. Phantom experiments showed that possible interference effects introduced by acquiring data from the two modalities simultaneously are small and non-significant. Further experiments can now investigate the benefits of simultaneous PET and

Large Area 2D and 3D Colloidal Photonic Crystals Fabricated by a Roll-to-Roll Langmuir-Blodgett Method.

Science.gov (United States)

Parchine, Mikhail; McGrath, Joe; Bardosova, Maria; Pemble, Martyn E

2016-06-14

We present our results on the fabrication of large area colloidal photonic crystals on flexible poly(ethylene terephthalate) (PET) film using a roll-to-roll Langmuir-Blodgett technique. Two-dimensional (2D) and three-dimensional (3D) colloidal photonic crystals from silica nanospheres (250 and 550 nm diameter) with a total area of up to 340 cm(2) have been fabricated in a continuous manner compatible with high volume manufacturing. In addition, the antireflective properties and structural integrity of the films have been enhanced via the use of a second roll-to-roll process, employing a slot-die coating of an optical adhesive over the photonic crystal films. Scanning electron microscopy images, atomic force microscopy images, and UV-vis optical transmission and reflection spectra of the fabricated photonic crystals are analyzed. This analysis confirms the high quality of the 2D and 3D photonic crystals fabricated by the roll-to-roll LB technique. Potential device applications of the large area 2D and 3D colloidal photonic crystals on flexible PET film are briefly reviewed.

New 'monolithic' templates and improved protocols for soft lithography and microchip fabrication

International Nuclear Information System (INIS)

Pallandre, Antoine; Pal, Debjani; Lambert, Bertrand de; Viovy, Jean-Louis; Fuetterer, Claus

2006-01-01

We report a new method for fast prototyping and fabrication of polydimethylsiloxane (PDMS) and plastic microfluidic chips. These methods share in common the preparation of monolithic masters which includes the fabrication of the planar support, the 'negative pattern' of the microchannels and the fluidic connectors. The monolithic templates are extremely robust compared to conventional ones made of silicon and SU-8, and easier to produce and cheaper than all-silicon or electroplated templates. In contrast to the above-mentioned methods, our process allows one to cast both micrometre- (e.g. the microchannel) and millimetre-sized structures (e.g. the fluidic connection to the outer world) in a single fabrication step. The 'monolithic template' strategy can be used to fabricate both elastomeric (e.g. poly(dimethyl siloxane (PDMS)) polyester thermoset masters and glassy polymeric (e.g. cyclic olefin copolymer (COC)) devices. In this study we also report on one step fabrication of elastomer chips and on surface modifications of the above mentioned monolithically fabricated masters in order to improve separation of the chip from the template

A small animal PET prototype based on Silicon Photomultipliers

International Nuclear Information System (INIS)

Marcatili, S; Belcari, N.; Bisogni, M.G.; Del Guerra, A.; Collazuol, G.; Pedreschi, E.; Spinella, F.; Sportelli, G.; Marzocca, C.

2011-01-01

Next generation PET scanners should full fill very high requirements in terms of spatial, energy and timing resolution. Modern scanner performances are inherently limited by the use of standard photomultiplier tubes. The use of Silicon Photomultiplier (Si P M) matrices is proposed for the construction of a small animal PET system consisting of two detector heads based on Lyso continuos crystals. The use of large area multi-pixel Silicon Photomultiplier (Si P M) detectors requires the development of a multichannel Digital Acquisition system (DAQ) as well as of a dedicated front-end in order not to degrade the intrinsic detector capabilities. At the University of Pisa and INFN Pisa we developed a DAQ board for the read-out of 2 64-pixel Si P M matrices in time coincidence for Positron Emission Tomography (PET) applications. The proof of principles is based on 64-pixel detectors, but the whole system has been conceived to be easily scalable to a higher number of channels. Here we describe the Group-V INFN DASi P M 2 (Development and Application of Si P M) project and related results.

Failure analysis of various monolithic posterior aesthetic dental crowns using finite element method

Science.gov (United States)

Porojan, Liliana; Topală, Florin

2017-08-01

The aim of the study was to assess the effect of material stiffness and load on the biomechanical performance of the monolithic full-coverage posterior aesthetic dental crowns using finite element analysis. Three restorative materials for monolithic dental crowns were selected for the study: zirconia; lithium disilicate glass-ceramic, and resin-based composite. Stresses were calculated in the crowns for all materials and in the teeth structures, under different load values. The experiments show that dental crowns made from all this new aesthetic materials processed by CAD/CAM technologies would be indicated as monolithic dental crowns for posterior areas.

Effect of pore size on performance of monolithic tube chromatography of large biomolecules.

Science.gov (United States)

Podgornik, Ales; Hamachi, Masataka; Isakari, Yu; Yoshimoto, Noriko; Yamamoto, Shuichi

2017-11-01

Effect of pore size on the performance of ion-exchange monolith tube chromatography of large biomolecules was investigated. Radial flow 1 mL polymer based monolith tubes of different pore sizes (1.5, 2, and 6 μm) were tested with model samples such as 20 mer poly T-DNA, basic proteins, and acidic proteins (molecular weight 14 000-670 000). Pressure drop, pH transient, the number of binding site, dynamic binding capacity, and peak width were examined. Pressure drop-flow rate curves and dynamic binding capacity values were well correlated with the nominal pore size. While duration of the pH transient curves depends on the pore size, it was found that pH duration normalized on estimated surface area was constant, indicating that the ligand density is the same. This was also confirmed by the constant number of binding site values being independent of pore size. The peak width values were similar to those for axial flow monolith chromatography. These results showed that it is easy to scale up axial flow monolith chromatography to radial flow monolith tube chromatography by choosing the right pore size in terms of the pressure drop and capacity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Monolithic pixels on moderate resistivity substrate and sparsifying readout architecture

CERN Document Server

Giubilato, P; Snoeys, W; Bisello, D; Marchioro, A; Battaglia, M; Demaria, L; Mansuy, S C; Pantano, D; Rousset, J; Mattiazzo, S; Kloukinas, K; Potenza, A; Ikemoto, Y; Rivetti, A; Chalmet, P; Mugnier, H; Silvestrin, L

2013-01-01

The LePix projects aim realizing a new generation monolithic pixel detectors with improved performances at lesser cost with respect to both current state of the art monolithic and hybrid pixel sensors. The detector is built in a 90 nm CMOS process on a substrate of moderate resistivity. This allows charge collection by drift while maintaining the other advantages usually offered by MAPS, like having a single piece detector and using a standard CMOS production line. The collection by drift mechanism, coupled to the low capacitance design of the collecting node made possible by the monolithic approach, provides an excellent signal to noise ratio straight at the pixel cell together with a radiation tolerance far superior to conventional un-depleted MAPS. The excellent signal-to-noise performance is demonstrated by the device ability to separate the 6 keV Fe-55 double peak at room temperature. To achieve high granularity (10-20 mu m pitch pixels) over large detector areas maintaining high readout speed, a complet...

Pet Allergy Quiz

Science.gov (United States)

... Treatments ▸ Allergies ▸ Pet Allergy ▸ Pet Allergy Quiz Share | Pet Allergy Quiz More than half of U.S. households ... cat family. Yet, millions of people suffer from pet allergies. Take this quiz to test your knowledge ...

THE CHANGE IN DEFORMATION CHARACTERISTICS OF CONCRETE MONOLITHIC HIGH-RISE BUILDINGS

Directory of Open Access Journals (Sweden)

V. V. Punahin

2009-03-01

Full Text Available In the article results of studies of deformation features of concrete on actuate cement for monolithic high-altitude buildings are presented. It is shown that in construction of the high-altitude monolithic buildings in a summer period of a year one should take into account the character of changing the concrete elasticity and plasticity in time, which differs from the same indices for the concrete of normal hardening.

Colorectal cancer staging: comparison of whole-body PET/CT and PET/MR.

Science.gov (United States)

Catalano, Onofrio A; Coutinho, Artur M; Sahani, Dushyant V; Vangel, Mark G; Gee, Michael S; Hahn, Peter F; Witzel, Thomas; Soricelli, Andrea; Salvatore, Marco; Catana, Ciprian; Mahmood, Umar; Rosen, Bruce R; Gervais, Debra

2017-04-01

Correct staging is imperative for colorectal cancer (CRC) since it influences both prognosis and management. Several imaging methods are used for this purpose, with variable performance. Positron emission tomography-magnetic resonance (PET/MR) is an innovative imaging technique recently employed for clinical application. The present study was undertaken to compare the staging accuracy of whole-body positron emission tomography-computed tomography (PET/CT) with whole-body PET/MR in patients with both newly diagnosed and treated colorectal cancer. Twenty-six patients, who underwent same day whole-body (WB) PET/CT and WB-PET/MR, were evaluated. PET/CT and PET/MR studies were interpreted by consensus by a radiologist and a nuclear medicine physician. Correlations with prior imaging and follow-up studies were used as the reference standard. Correct staging was compared between methods using McNemar's Chi square test. The two methods were in agreement and correct for 18/26 (69%) patients, and in agreement and incorrect for one patient (3.8%). PET/MR and PET/CT stages for the remaining 7/26 patients (27%) were discordant, with PET/MR staging being correct in all seven cases. PET/MR significantly outperformed PET/CT overall for accurate staging (P = 0.02). PET/MR outperformed PET/CT in CRC staging. PET/MR might allow accurate local and distant staging of CRC patients during both at the time of diagnosis and during follow-up.

Preparation of polymer monolithic column functionalized by arsonic acid groups for mixed-mode capillary liquid chromatography.

Science.gov (United States)

Qin, Zhang-Na; Yu, Qiong-Wei; Wang, Ren-Qi; Feng, Yu-Qi

2018-04-27

A mixed-mode polymer monolithic column functionalized by arsonic acid groups was prepared by single-step in situ copolymerization of monomers p-methacryloylaminophenylarsonic acid (p-MAPHA) and pentaerythritol triacrylate (PETA). The prepared poly(p-MAPHA-co-PETA) monolithic column has a homogeneous monolithic structure with good permeability and mechanical stability. Zeta potential measurements reveal that the monolithic stationary phase holds a negative surface charge when the mobile phase resides in the pH range of 3.0-8.0. The retention mechanisms of prepared monolithic column are explored by the separation of selected polycyclic aromatic hydrocarbons (PAHs), nucleosides, and three basic compounds. The results indicate that the column functions in three different separation modes associated with reversed-phase chromatography based on hydrophobic interaction, hydrophilic interaction chromatography, and cation-exchange chromatography. The column efficiency of prepared monolithic column is estimated to be 70,000 and 76,000 theoretical plates/m for thiourea and naphthalene, respectively, at a linear flow velocity of 0.85 mm/s using acetonitrile/H 2 O (85/15, v/v) as the mobile phase. Furthermore, an analysis of the retention factors obtained for the PAHs indicates that the prepared monolithic column exhibits good reproducibility with relative standard deviations of 2.9%, 4.0%, and 4.7% based on run-to-run injections, column-to-column preparation, and batch-to-batch preparation, respectively. Finally, we investigate the separation performance of the proposed monolithic column for select phenols, sulfonamides, nucleobases and nucleosides. Copyright © 2018 Elsevier B.V. All rights reserved.

High-precision position estimation in PET using artificial neural networks

Energy Technology Data Exchange (ETDEWEB)

Mateo, F. [Digital Systems Design Group (DSD), Instituto de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas (ITACA), Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)], E-mail: fermaji@upvnet.upv.es; Aliaga, R.J.; Ferrando, N.; Martinez, J.D.; Herrero, V.; Lerche, Ch.W.; Colom, R.J.; Monzo, J.M.; Sebastia, A.; Gadea, R. [Digital Systems Design Group (DSD), Instituto de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas (ITACA), Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

2009-06-01

Traditionally, the most popular technique to predict the impact position of gamma photons on a PET detector has been Anger's logic. However, it introduces nonlinearities that compress the light distribution, reducing the useful field of view and the spatial resolution, especially at the edges of the scintillator crystal. In this work, we make use of neural networks to address a bias-corrected position estimation from real stimulus obtained from a 2D PET system setup. The preprocessing and data acquisition were performed by separate custom boards, especially designed for this application. The results show that neural networks yield a more uniform field of view while improving the systematic error and the spatial resolution. Therefore, they stand as a better performing and readily available alternative to classic positioning methods.

High-precision position estimation in PET using artificial neural networks

International Nuclear Information System (INIS)

Mateo, F.; Aliaga, R.J.; Ferrando, N.; Martinez, J.D.; Herrero, V.; Lerche, Ch.W.; Colom, R.J.; Monzo, J.M.; Sebastia, A.; Gadea, R.

2009-01-01

Traditionally, the most popular technique to predict the impact position of gamma photons on a PET detector has been Anger's logic. However, it introduces nonlinearities that compress the light distribution, reducing the useful field of view and the spatial resolution, especially at the edges of the scintillator crystal. In this work, we make use of neural networks to address a bias-corrected position estimation from real stimulus obtained from a 2D PET system setup. The preprocessing and data acquisition were performed by separate custom boards, especially designed for this application. The results show that neural networks yield a more uniform field of view while improving the systematic error and the spatial resolution. Therefore, they stand as a better performing and readily available alternative to classic positioning methods.

Review on recent and advanced applications of monoliths and related porous polymer gels in micro-fluidic devices

International Nuclear Information System (INIS)

Vazquez, Mercedes; Paull, Brett

2010-01-01

This review critically summarises recent novel and advanced achievements in the application of monolithic materials and related porous polymer gels in micro-fluidic devices appearing within the literature over the period of the last 5 years (2005-2010). The range of monolithic materials has developed rapidly over the past decade, with a diverse and highly versatile class of materials now available, with each exhibiting distinct porosities, pore sizes, and a wide variety of surface functionalities. A major advantage of these materials is their ease of preparation in micro-fluidic channels by in situ polymerisation, leading to monolithic materials being increasingly utilised for a larger variety of purposes in micro-fluidic platforms. Applications of porous polymer monoliths, silica-based monoliths and related homogeneous porous polymer gels in the preparation of separation columns, ion-permeable membranes, preconcentrators, extractors, electrospray emitters, micro-valves, electrokinetic pumps, micro-reactors and micro-mixers in micro-fluidic devices are discussed herein. Procedures used in the preparation of monolithic materials in micro-channels, as well as some practical aspects of the micro-fluidic chip fabrication are addressed. Recent analytical/bioanalytical and catalytic applications of the final micro-fluidic devices incorporating monolithic materials are also reviewed.

TOF-PET/MR和TOF-PET/CT在体部恶性肿瘤SUVmax值的比较%Comparision of SUVmax of TOF-PET/MR and TOF-PET/CT in body malignant tumor

Institute of Scientific and Technical Information of China (English)

宋天彬; 卢洁; 崔碧霄; 马杰; 杨宏伟; 马蕾; 梁志刚

2017-01-01

目的 探讨时间飞行(TOF)技术PET/CT和PET/MR检查体部恶性病变SUVmax值的一致性.方法 回顾性分析接受TOF-PET/CT和TOF-PET/MR检查的体部恶性肿瘤患者20例,分为先PET/CT后PET/MR组和先PET/MR后PET/CT组,每组10例.采用Bland-Altma图评价两次检查病灶SUVmax值的一致性,采用多因素方差分析评价扫描顺序和机器类型对病灶的SUVmax测量值的影响.结果 TOF-PET/CT与TOF-PET/MR检查病灶的SUVmax值有较好的一致性[先PET/CT后PET/MR组:均值差为3.06,95％CI(-7.5,13.6),先PET/MR后PET/CT组:均值差3.0,95％CI(-2.4,8.3)].扫描顺序对于恶性病灶的SUVmax有影响(F=46.00,P＜0.001),而机器类型对恶性病灶的SUVmax值无影响(F=0.005,P=0.95).结论 TOF-PET/MR和TOF-PET/CT在体部恶性病变SUVmax值测量方面具有相当的诊断价值,且延迟显像SUVmax的增加与采集时间有关,而与检查机器类型无关.%Objective To explore the consistency of time-of-flight (TOF) technology of PET/MRI and PET/CT for max standardized uptake value (SUVmax) of body malignant tumors.Methods A retrospective analysis of TOF-PET/CT and TOF-PET/MR imaging data about twenty patients with body malignant tumors was performed.Patients were divided into two groups (each n=10),including PET/CT first and sequentially PET/MR group and PET/MR first and sequentially PET/CT group.Bland-Altman figure was used to evaluate consistency of SUVmax of malignant lesions between TOF-PET/CT and TOF-PET/MR.Multi-way ANOVA was used to analysis effect of machine type and exam order on SUVmaxof malignant lesions in TOF-PET/CT and TOF-PET/MR.Results SUVmax of malignant lesions in TOF-PET/CT and TOF-PET/MR had good consistency in two groups (PET/CT first and sequentially PET/MR group:Mean difference was 3.06,95％CI was [-7.5,13.6];PET/MR first and sequentially PET/CT group:Mean difference was 3.0,95％CI was [-2.4,8.3]).SUVmax was not influenced by machine type (F=0.005,P=0.95),but exam order (F=46.00,P＜0

Monolithic millimeter-wave and picosecond electronic technologies

International Nuclear Information System (INIS)

Talley, W.K.; Luhmann, N.C.

1996-01-01

Theoretical and experimental studies into monolithic millimeter-wave and picosecond electronic technologies have been undertaken as a collaborative project between the Lawrence Livermore National Laboratory (LLNL) and the University of California Department of Applied Science Coherent Millimeter-Wave Group under the auspices of the Laboratory Directed Research and Development Program at LLNL. The work involves the design and fabrication of monolithic frequency multiplier, beam control, and imaging arrays for millimeter-wave imaging and radar, as well as the development of high speed nonlinear transmission lines for ultra-wideband radar imaging, time domain materials characterization and magnetic fusion plasma applications. In addition, the Coherent Millimeter-Wave Group is involved in the fabrication of a state-of-the-art X-band (∼8-11 GHz) RF photoinjector source aimed at producing psec high brightness electron bunches for advanced accelerator and coherent radiation generation studies

Silicon monolithic microchannel-cooled laser diode array

International Nuclear Information System (INIS)

Skidmore, J. A.; Freitas, B. L.; Crawford, J.; Satariano, J.; Utterback, E.; DiMercurio, L.; Cutter, K.; Sutton, S.

2000-01-01

A monolithic microchannel-cooled laser diode array is demonstrated that allows multiple diode-bar mounting with negligible thermal cross talk. The heat sink comprises two main components: a wet-etched Si layer that is anodically bonded to a machined glass block. The continuous wave (cw) thermal resistance of the 10 bar diode array is 0.032 degree sign C/W, which matches the performance of discrete microchannel-cooled arrays. Up to 1.5 kW/cm 2 is achieved cw at an emission wavelength of ∼808 nm. Collimation of a diode array using a monolithic lens frame produced a 7.5 mrad divergence angle by a single active alignment. This diode array offers high average power/brightness in a simple, rugged, scalable architecture that is suitable for large two-dimensional areas. (c) 2000 American Institute of Physics

Carprofen-imprinted monolith prepared by reversible addition-fragmentation chain transfer polymerization in room temperature ionic liquids.

Science.gov (United States)

Ban, Lu; Han, Xu; Wang, Xian-Hua; Huang, Yan-Ping; Liu, Zhao-Sheng

2013-10-01

To obtain fast separation, ionic liquids were used as porogens first in combination with reversible addition-fragmentation chain transfer (RAFT) polymerization to prepare a new type of molecularly imprinted polymer (MIP) monolith. The imprinted monolithic column was synthesized using a mixture of carprofen (template), 4-vinylpyridine, ethylene glycol dimethacrylate, [BMIM]BF4, and chain transfer agent (CTA). Some polymerization factors, such as template-monomer molar ratio, the degree of crosslinking, the composition of the porogen, and the content of CTA, on the column efficiency and imprinting effect of the resulting MIP monolith were systematically investigated. Affinity screening of structurally similar compounds with the template can be achieved in 200 s on the MIP monolith due to high column efficiency (up to 12,070 plates/m) and good column permeability. Recognition mechanism of the imprinted monolith was also investigated.

Monoliths of activated carbon from coconut shell and impregnation with nickel and copper

International Nuclear Information System (INIS)

Giraldo, Liliana; Moreno, Juan

2008-01-01

A series of different monoliths of activated carbon were prepared from coconut shell By means of chemical activation with phosphoric acid at different concentrations Without using binders or plastics. The monolith that developed the biggest surface area was impregnated by humidic route with solutions of Ni and Cu at different molar relations. The structures were characterized by N2 adsorption at 77 K, and the morphology was explored by means of scanning electron microscopy. The carbonaceous materials obtained, Nickel-Copper-Monolith, were analyzed by Thermal Programmed Reduction (TPR). The experimental results indicated that the activation with the acid generated a micro porosity, with micropores volume between 0.40 and 0.81 cm 3 g-1 and surface areas between 703 and 1450 m 2 g-1, and a good mechanical properties. It shows that, both the copper and the nickel, are fixed to the monolith and TPR's results are interpreted when these molar relation are modified.

Poly(ethylenimine)-Functionalized Monolithic Alumina Honeycomb Adsorbents for CO2 Capture from Air.

Science.gov (United States)

Sakwa-Novak, Miles A; Yoo, Chun-Jae; Tan, Shuai; Rashidi, Fereshteh; Jones, Christopher W

2016-07-21