The Experts below are selected from a list of 34101 Experts worldwide ranked by ideXlab platform
Jun Hatazawa - One of the best experts on this subject based on the ideXlab platform.
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development of a pixelated gso gamma camera system with tungsten parallel hole collimator for Single Photon Imaging
Medical Physics, 2012Co-Authors: Seiichi Yamamoto, Hiroshi Watabe, Yasukazu Kanai, Eku Shimosegawa, Jun HatazawaAbstract:Purpose: In small animal Imaging using a Single Photon emitting radionuclide, a high resolution gamma camera is required. Recently, position sensitive photomultiplier tubes (PSPMTs) with high quantum efficiency have been developed. By combining these with nonhygroscopic scintillators with a relatively low light output, a high resolution gamma camera can become useful for low energy gamma Photons. Therefore, the authors developed a gamma camera by combining a pixelated Ce-doped Gd{sub 2}SiO{sub 5} (GSO) block with a high quantum efficiency PSPMT. Methods: GSO was selected for the scintillator, because it is not hygroscopic and does not contain any natural radioactivity. An array of 1.9 mm x 1.9 mm x 7 mm individual GSO crystal elements was constructed. These GSOs were combined with a 0.1-mm thick reflector to form a 22 x 22 matrix and optically coupled to a high quantum efficiency PSPMT (H8500C-100 MOD8). The GSO gamma camera was encased in a tungsten gamma-ray shield with tungsten pixelated parallel hole collimator, and the basic performance was measured for Co-57 gamma Photons (122 keV). Results: In a two-dimensional position histogram, all pixels were clearly resolved. The energy resolution was {approx}15% FWHM. With the 20-mm thick tungsten pixelated collimator, the spatial resolution was 4.4-mmmore » FWHM 40 mm from the collimator surface, and the sensitivity was {approx}0.05%. Phantom and small animal images were successfully obtained with our developed gamma camera. Conclusions: These results confirmed that the developed pixelated GSO gamma camera has potential as an effective instrument for low energy gamma Photon Imaging.« less
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development of a high resolution si pm based gamma camera system
Physics in Medicine and Biology, 2011Co-Authors: Hiroshi Watabe, Yasukazu Kanai, Masao Imaizumi, Tadashi Watabe, Eku Shimosegawa, Jun HatazawaAbstract:A silicon photomultiplier (Si-PM) is a promising photodetector for PET, especially for PET/MRI combined systems, due to its high gain, small size, and lower sensitivity to static magnetic fields. However, these properties are also promising for gamma camera systems for Single-Photon Imaging. We developed an ultra-high-resolution Si-PM-based compact gamma camera system for small animals. Y2SiO5:Ce (YSO) was selected as scintillators because of its high light output and no natural radioactivity. The gamma camera consists of 0.6 mm × 0.6 mm × 6 mm YSO pixels combined with a 0.1 mm thick reflector to form a 17 × 17 matrix that was optically coupled to a Si-PM array (Hamamatsu multi-pixel Photon counter S11064-050P) with a 2 mm thick light guide. The YSO block size was 12 mm × 12 mm. The YSO gamma camera was encased in a 5 mm thick gamma shield, and a parallel hole collimator was mounted in front of the camera (0.5 mm hole, 0.7 mm separation, 5 mm thick). The two-dimensional distribution for the Co-57 gamma Photons (122 keV) was almost resolved. The energy resolution was 24.4% full-width at half-maximum (FWHM) for the Co-57 gamma Photons. The spatial resolution at 1.5 mm from the collimator surface was 1.25 mm FWHM measured using a 1 mm diameter Co-57 point source. Phantom and small animal images were successfully obtained. We conclude that a Si-PM-based gamma camera is promising for molecular Imaging research.
S H Moseley - One of the best experts on this subject based on the ideXlab platform.
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improved energy resolution of x ray Single Photon Imaging spectrometers using superconducting tunnel junctions
Journal of Applied Physics, 2001Co-Authors: Luigi Frunzio, C M Wilson, D E Prober, Andrew Szymkowiak, S H MoseleyAbstract:We present measurements of the energy resolution of improved Single-Photon Imaging x-ray spectrometers based on superconducting tunnel junctions. The devices have a Ta film absorber with an Al/AlOx/Al tunnel junction on each end. Recent device designs optimized for better quasiparticle cooling in the Al trap obtain an energy resolution of 13 eV full width at half maximum for a Photon energy E=5.9 keV, an improvement of a factor of two over earlier devices. We also determined that the niobium contact used in previous devices degraded the energy resolution in the center section of the absorber. With a different contact configuration, we have eliminated this spatial broadening.
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Single Photon Imaging x ray spectrometers
IEEE Transactions on Applied Superconductivity, 1999Co-Authors: K Segall, Michael C Gaidis, C M Wilson, D E Prober, Andrew Szymkowiak, A K Davies, Richard E Lathrop, S H MoseleyAbstract:We have developed superconducting, Single-Photon Imaging X-ray detectors with an energy resolution of 26 eV FWHM at 6 keV and a spatial resolution of 0.5 /spl mu/m over an effective area of 18 /spl mu/m/spl times/100 /spl mu/m. The energy resolution is among the best reported for this kind of detector and is within a factor of /spl ap/4 of its theoretical limit. The calculated absorption efficiency of the detector is 28%. Scaling to larger areas and higher quantum efficiency appear possible. We discuss the device design and readout along with possible sources of resolution broadening.
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Single Photon Imaging x ray spectrometers using low noise current preamplifiers with dc voltage bias
IEEE Transactions on Applied Superconductivity, 1997Co-Authors: S Friedrich, K Segall, Michael C Gaidis, C M Wilson, D E Prober, P J Kindlmann, Andrew Szymkowiak, S H MoseleyAbstract:We have developed superconducting Single-Photon Imaging X-ray detectors with an energy resolution of 54 eV at 6 keV and a spatial resolution of 1 /spl mu/m over an effective length of 40 /spl mu/m. They utilize a current-sensitive low-noise preamplifier with a dc voltage bias. It has a signal bandwidth of 300 kHz, current noise of i/sub n/=0.26 pA//spl radic/(Hz) and voltage noise of e/sub n/=0.5 nV//spl radic/(Hz) with an input capacitance of 200 pF under operating conditions. Injected pulses with a charge Q=3.7/spl middot/10/sup 6/ electrons have been measured with a standard deviation /spl sigma/Q=3400 electrons, corresponding to an electronic noise of 13 eV at 6 keV.
Hiroshi Watabe - One of the best experts on this subject based on the ideXlab platform.
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development of a pixelated gso gamma camera system with tungsten parallel hole collimator for Single Photon Imaging
Medical Physics, 2012Co-Authors: Seiichi Yamamoto, Hiroshi Watabe, Yasukazu Kanai, Eku Shimosegawa, Jun HatazawaAbstract:Purpose: In small animal Imaging using a Single Photon emitting radionuclide, a high resolution gamma camera is required. Recently, position sensitive photomultiplier tubes (PSPMTs) with high quantum efficiency have been developed. By combining these with nonhygroscopic scintillators with a relatively low light output, a high resolution gamma camera can become useful for low energy gamma Photons. Therefore, the authors developed a gamma camera by combining a pixelated Ce-doped Gd{sub 2}SiO{sub 5} (GSO) block with a high quantum efficiency PSPMT. Methods: GSO was selected for the scintillator, because it is not hygroscopic and does not contain any natural radioactivity. An array of 1.9 mm x 1.9 mm x 7 mm individual GSO crystal elements was constructed. These GSOs were combined with a 0.1-mm thick reflector to form a 22 x 22 matrix and optically coupled to a high quantum efficiency PSPMT (H8500C-100 MOD8). The GSO gamma camera was encased in a tungsten gamma-ray shield with tungsten pixelated parallel hole collimator, and the basic performance was measured for Co-57 gamma Photons (122 keV). Results: In a two-dimensional position histogram, all pixels were clearly resolved. The energy resolution was {approx}15% FWHM. With the 20-mm thick tungsten pixelated collimator, the spatial resolution was 4.4-mmmore » FWHM 40 mm from the collimator surface, and the sensitivity was {approx}0.05%. Phantom and small animal images were successfully obtained with our developed gamma camera. Conclusions: These results confirmed that the developed pixelated GSO gamma camera has potential as an effective instrument for low energy gamma Photon Imaging.« less
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development of a high resolution si pm based gamma camera system
Physics in Medicine and Biology, 2011Co-Authors: Hiroshi Watabe, Yasukazu Kanai, Masao Imaizumi, Tadashi Watabe, Eku Shimosegawa, Jun HatazawaAbstract:A silicon photomultiplier (Si-PM) is a promising photodetector for PET, especially for PET/MRI combined systems, due to its high gain, small size, and lower sensitivity to static magnetic fields. However, these properties are also promising for gamma camera systems for Single-Photon Imaging. We developed an ultra-high-resolution Si-PM-based compact gamma camera system for small animals. Y2SiO5:Ce (YSO) was selected as scintillators because of its high light output and no natural radioactivity. The gamma camera consists of 0.6 mm × 0.6 mm × 6 mm YSO pixels combined with a 0.1 mm thick reflector to form a 17 × 17 matrix that was optically coupled to a Si-PM array (Hamamatsu multi-pixel Photon counter S11064-050P) with a 2 mm thick light guide. The YSO block size was 12 mm × 12 mm. The YSO gamma camera was encased in a 5 mm thick gamma shield, and a parallel hole collimator was mounted in front of the camera (0.5 mm hole, 0.7 mm separation, 5 mm thick). The two-dimensional distribution for the Co-57 gamma Photons (122 keV) was almost resolved. The energy resolution was 24.4% full-width at half-maximum (FWHM) for the Co-57 gamma Photons. The spatial resolution at 1.5 mm from the collimator surface was 1.25 mm FWHM measured using a 1 mm diameter Co-57 point source. Phantom and small animal images were successfully obtained. We conclude that a Si-PM-based gamma camera is promising for molecular Imaging research.
Franco Zappa - One of the best experts on this subject based on the ideXlab platform.
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Smart-pixel for 3D ranging imagers based on Single-Photon avalanche diode and time-to-digital converter
Proc. SPIE 8033 Advanced Photon Counting Techniques V, 2011Co-Authors: Branko Marković, Simone Tisa, Alberto Tosi, Franco ZappaAbstract:We present a “smart-pixel” suitable for implementation of monolithic Single-Photon Imaging arrays aimed at 3D ranging applications by means of the direct time-of-flight detection (like LIDAR systems), but also for Photon timing applications (like FLIM, FCS, FRET). The pixel includes a Single-Photon Avalanche Diode (SPAD) and a Time-to-Digital Converter (TDC) monolithically designed and manufactured in the same chip, and it is able to detect Single Photons and to measure in-pixel the time delay between a START signal (e.g. laser excitation, LIDAR flash) and a Photon detection (e.g. back reflection from a target object). In order to provide both wide dynamic range, high time resolution and very high linearity, we devised a TDC architecture based on an interpolation technique. A “coarse” counter counts the number of reference-clock rising-edges between START and STOP, while high resolution is achieved by means of two interpolators, which measure the time elapsed between START (and STOP) signal and a successive clock edge. In an array with many pixels, multiple STOP channels are needed while just one START channel is necessary if the START event is common to all channels. We report on the design and characterization of prototype circuits, fabricated in a 0.35 μm standard CMOS technology containing complete conversion channels (i.e. 20-μm active-area diameter SPAD, quenching circuitry, and TDC). With a 100 MHz reference clock, the TDC provides a time resolution of 10 ps, a dynamic range of 160 ns and DNL < 1% LSB rms.
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principles and features of Single Photon avalanche diode arrays
Sensors and Actuators A-physical, 2007Co-Authors: Franco Zappa, Simone Tisa, Alberto Tosi, S CovaAbstract:This is the first of two serial papers dealing on Single-Photon avalanche diode (SPAD) topics. Aim of the series is to discuss in depth the design and fabrication of our SPAD-A array system for two-dimensional Single-Photon Imaging, able to count and time-tag Single Photons by means of a monolithic array sensor. This paper deals with the device structure and characterization. The second paper will present the developed fast electronics and will show the overall performance reached in passive, active, and gated regimes. In this first paper we review the working principle and the features of Single-Photon detector pixels, with particular attention to the monolithic array integration. Then we discuss design criteria, trade-offs, and how to chose operating conditions to attain best performances out of individual pixels. Finally, experimental data will be thoroughly discussed.
Eku Shimosegawa - One of the best experts on this subject based on the ideXlab platform.
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development of a pixelated gso gamma camera system with tungsten parallel hole collimator for Single Photon Imaging
Medical Physics, 2012Co-Authors: Seiichi Yamamoto, Hiroshi Watabe, Yasukazu Kanai, Eku Shimosegawa, Jun HatazawaAbstract:Purpose: In small animal Imaging using a Single Photon emitting radionuclide, a high resolution gamma camera is required. Recently, position sensitive photomultiplier tubes (PSPMTs) with high quantum efficiency have been developed. By combining these with nonhygroscopic scintillators with a relatively low light output, a high resolution gamma camera can become useful for low energy gamma Photons. Therefore, the authors developed a gamma camera by combining a pixelated Ce-doped Gd{sub 2}SiO{sub 5} (GSO) block with a high quantum efficiency PSPMT. Methods: GSO was selected for the scintillator, because it is not hygroscopic and does not contain any natural radioactivity. An array of 1.9 mm x 1.9 mm x 7 mm individual GSO crystal elements was constructed. These GSOs were combined with a 0.1-mm thick reflector to form a 22 x 22 matrix and optically coupled to a high quantum efficiency PSPMT (H8500C-100 MOD8). The GSO gamma camera was encased in a tungsten gamma-ray shield with tungsten pixelated parallel hole collimator, and the basic performance was measured for Co-57 gamma Photons (122 keV). Results: In a two-dimensional position histogram, all pixels were clearly resolved. The energy resolution was {approx}15% FWHM. With the 20-mm thick tungsten pixelated collimator, the spatial resolution was 4.4-mmmore » FWHM 40 mm from the collimator surface, and the sensitivity was {approx}0.05%. Phantom and small animal images were successfully obtained with our developed gamma camera. Conclusions: These results confirmed that the developed pixelated GSO gamma camera has potential as an effective instrument for low energy gamma Photon Imaging.« less
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development of a high resolution si pm based gamma camera system
Physics in Medicine and Biology, 2011Co-Authors: Hiroshi Watabe, Yasukazu Kanai, Masao Imaizumi, Tadashi Watabe, Eku Shimosegawa, Jun HatazawaAbstract:A silicon photomultiplier (Si-PM) is a promising photodetector for PET, especially for PET/MRI combined systems, due to its high gain, small size, and lower sensitivity to static magnetic fields. However, these properties are also promising for gamma camera systems for Single-Photon Imaging. We developed an ultra-high-resolution Si-PM-based compact gamma camera system for small animals. Y2SiO5:Ce (YSO) was selected as scintillators because of its high light output and no natural radioactivity. The gamma camera consists of 0.6 mm × 0.6 mm × 6 mm YSO pixels combined with a 0.1 mm thick reflector to form a 17 × 17 matrix that was optically coupled to a Si-PM array (Hamamatsu multi-pixel Photon counter S11064-050P) with a 2 mm thick light guide. The YSO block size was 12 mm × 12 mm. The YSO gamma camera was encased in a 5 mm thick gamma shield, and a parallel hole collimator was mounted in front of the camera (0.5 mm hole, 0.7 mm separation, 5 mm thick). The two-dimensional distribution for the Co-57 gamma Photons (122 keV) was almost resolved. The energy resolution was 24.4% full-width at half-maximum (FWHM) for the Co-57 gamma Photons. The spatial resolution at 1.5 mm from the collimator surface was 1.25 mm FWHM measured using a 1 mm diameter Co-57 point source. Phantom and small animal images were successfully obtained. We conclude that a Si-PM-based gamma camera is promising for molecular Imaging research.