WorldWideScience

Sample records for pixellated gamma-camera based

  1. A pixellated gamma-camera based on CdTe detectors clinical interests and performances

    CERN Document Server

    Chambron, J; Eclancher, B; Scheiber, C; Siffert, P; Hage-Ali, M; Regal, R; Kazandjian, A; Prat, V; Thomas, S; Warren, S; Matz, R; Jahnke, A; Karman, M; Pszota, A; Németh, L

    2000-01-01

    A mobile gamma camera dedicated to nuclear cardiology, based on a 15 cmx15 cm detection matrix of 2304 CdTe detector elements, 2.83 mmx2.83 mmx2 mm, has been developed with a European Community support to academic and industrial research centres. The intrinsic properties of the semiconductor crystals - low-ionisation energy, high-energy resolution, high attenuation coefficient - are potentially attractive to improve the gamma-camera performances. But their use as gamma detectors for medical imaging at high resolution requires production of high-grade materials and large quantities of sophisticated read-out electronics. The decision was taken to use CdTe rather than CdZnTe, because the manufacturer (Eurorad, France) has a large experience for producing high-grade materials, with a good homogeneity and stability and whose transport properties, characterised by the mobility-lifetime product, are at least 5 times greater than that of CdZnTe. The detector matrix is divided in 9 square units, each unit is composed ...

  2. Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors

    OpenAIRE

    Y Calderón; Chmeissani, M.; Kolstein, M.; De Lorenzo, G.

    2014-01-01

    A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm2 area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm3. The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(G...

  3. Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors.

    Science.gov (United States)

    Calderón, Y; Chmeissani, M; Kolstein, M; De Lorenzo, G

    2014-06-01

    A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm(2) area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm(3). The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(GAMOS) and the Origin Ensemble(OE) algorithm is used for the image reconstruction. The simulation shows that the camera can operate with up to 10(4) Bq source activities with equal efficiency and is completely saturated at 10(9) Bq. The efficiency of the system is evaluated using a simulated (18)F point source phantom in the center of the Field-of-View (FOV) achieving an intrinsic efficiency of 0.4 counts per second per kilobecquerel. The spatial resolution measured from the point spread function (PSF) shows a FWHM of 1.5 mm along the direction perpendicular to the scatterer, making it possible to distinguish two points at 3 mm separation with a peak-to-valley ratio of 8.

  4. Optimal configuration of a low-dose breast-specific gamma camera based on semiconductor CdZnTe pixelated detectors

    Science.gov (United States)

    Genocchi, B.; Pickford Scienti, O.; Darambara, DG

    2017-05-01

    Breast cancer is one of the most frequent tumours in women. During the ‘90s, the introduction of screening programmes allowed the detection of cancer before the palpable stage, reducing its mortality up to 50%. About 50% of the women aged between 30 and 50 years present dense breast parenchyma. This percentage decreases to 30% for women between 50 to 80 years. In these women, mammography has a sensitivity of around 30%, and small tumours are covered by the dense parenchyma and missed in the mammogram. Interestingly, breast-specific gamma-cameras based on semiconductor CdZnTe detectors have shown to be of great interest to early diagnosis. Infact, due to the high energy, spatial resolution, and high sensitivity of CdZnTe, molecular breast imaging has been shown to have a sensitivity of about 90% independently of the breast parenchyma. The aim of this work is to determine the optimal combination of the detector pixel size, hole shape, and collimator material in a low dose dual head breast specific gamma camera based on a CdZnTe pixelated detector at 140 keV, in order to achieve high count rate, and the best possible image spatial resolution. The optimal combination has been studied by modeling the system using the Monte Carlo code GATE. Six different pixel sizes from 0.85 mm to 1.6 mm, two hole shapes, hexagonal and square, and two different collimator materials, lead and tungsten were considered. It was demonstrated that the camera achieved higher count rates, and better signal-to-noise ratio when equipped with square hole, and large pixels (> 1.3 mm). In these configurations, the spatial resolution was worse than using small pixel sizes (< 1.3 mm), but remained under 3.6 mm in all cases.

  5. Development of Active Pixel Photodiode Sensors for Gamma Camera Application

    CERN Document Server

    Salahuddin, Nur Sultan; Heruseto, Brahmantyo; Parmentier, Michel

    2011-01-01

    We designed new photodiodes sensors including current mirror amplifiers. These photodiodes have been fabricated using a CMOS 0.6 micrometers process from Austria Micro System (AMS). The Photodiode areas are respectiveley 1mm x 1mm and 0.4mm x 0.4mm with fill factor 98 % and total chip area is 2 square millimetres. The sensor pixels show a logarithmic response in illumination and are capable of detecting very low blue light (less than 0.5 lux) . These results allow to use our sensor in new Gamma Camera solid-state concept.

  6. Physical characterization of a discrete pixel gamma camera; Caracterizacion fisica de una gammacamara de pixel discreto

    Energy Technology Data Exchange (ETDEWEB)

    Saldana Gutierrez, P.; Puchal Ane, R.

    2012-07-01

    The development of new semiconductor materials for the last twenty years has led to the appearance of compounds such as CdTe (Cadmium Telluride) or CZT (Cadmium-Zinc Telluride), which have application in c-ray detectors in nuclear medicine. These new semiconductors have, among other properties that make them interesting, an excellent spatial and energy resolution, can operate at room temperature and high efficiency. The aim of this work is the physical characterization of the CdTe based MINICAM 2 (EURORAD) portable semiconductor gamma camera, subjecting it to some of the NEMA standard tests. We studied the spatial and energy resolution, uniformity and sensitivity, using different radioisotopes. The obtained results showed a higher spatial and energy resolution of the camera compared to the NaI(Tl) scintillator crystals, while the performances were similar in uniformity and sensitivity tests. (Author)

  7. Study of performance of small gamma camera consisting of crystal pixel array and position sensitive photomultiplier tube

    Institute of Scientific and Technical Information of China (English)

    ZHU Jie; LIU Shi-Tao; LEI Xiao-Wen; YAN Tian-Xin; XU Zi-Zong; WANG Zhao-Min

    2005-01-01

    The performance of gamma camera with NaI(T1) array coupled with position sensitive photomultiplier tube (PSPMT) R2486 has been studied. The pixel size of NaI(T1) crystal is 2mm×2mm and the overall dimension of the array is 48.2mm×48.2mm×5mm. There are 484 pixels in a 22×22 matrix. Because each pixel can produce a much focused light spot and restrict the spread of photons, position resolution of the gamma camera is mainly determined by pixel size. It is shown that crystal array pixel can reduce shrinkage effect and improve intrinsic position resolution greatly via restricting the spread of photons. Experimental results demonstrate that its position resolution and linearity are much improved comparing with the gamma camera using planar crystals coupled with PSPMT.

  8. Small prototype gamma camera based on wavelength-shifting fibres

    Science.gov (United States)

    Castro, I. F.; Soares, A. J.; Moutinho, L. M.; Veloso, J. F. C. A.

    2012-01-01

    We are studying and developing a small field of view gamma camera based on wavelength-shifting optical fibres coupled to both sides of an inorganic scintillation crystal and using for the light readout highly sensitive photon detectors, namely silicon photomultipliers (SiPMs) and high efficiency multi-anode photomultiplier tubes (MaPMTs). The coupling of the fibres in orthogonal directions allows obtaining 2D position information, while the energy signal is provided by a PMT. A first prototype laboratory system has been developed using a custom-made 50 × 50 × 3 mm3 CsI(Na) crystal with embedded 1 mm diameter fibres and reading out the light from several fibres in each direction, both with individual SiPMs and with a MaPMT. Proof-of-concept studies and results obtained with these systems using 57Co are presented and compared. The application of optical fibres combined with highly sensitive SiPMs or MaPMTs as light sensors in a compact gamma camera has the potential to improve the spatial resolution to the 1-2 mm FWHM level, thus improving the sensitivity of typical scintigraphy techniques and making such camera clinically useful. Results demonstrate the feasibility and imaging capability of the system using both types of photon detectors for imaging. In the case of SiPMs, a temperature cooling system is necessary to improve the SNR and consequently achieve a better imaging performance. The development of larger prototypes with 10 × 10 cm2 and 12 × 12 cm2 is under way, using 1 mm2 SiPMs and 64 anode PMTs, respectively.

  9. Performance evaluation of a hand-held, semiconductor (CdZnTe)-based gamma camera

    CERN Document Server

    Abe, A; Lee, J; Oka, T; Shizukuishi, K; Kikuchi, T; Inoue, T; Jimbo, M; Ryuo, H; Bickel, C

    2003-01-01

    We have designed and developed a small field of view gamma camera, the eZ SCOPE, based on use of a CdZnTe semiconductor. This device utilises proprietary signal processing technology and an interface to a computer-based imaging system. The purpose of this study was to evaluate the performance of the eZ scope in comparison with currently employed gamma camera technology. The detector is a single wafer of 5-mm-thick CdZnTe that is divided into a 16 x 16 array (256 pixels). The sensitive area of the detector is a square of dimension 3.2 cm. Two parallel-hole collimators are provided with the system and have a matching (256 hole) pattern to the CdZnTe detector array: a low-energy, high-resolution parallel-hole (LEHR) collimator fabricated of lead and a low-energy, high-sensitivity parallel-hole (LEHS) collimator fabricated of tungsten. Performance measurements and the data analysis were done according to the procedures of the NEMA standard. We also studied the long-term stability of the system with continuous use...

  10. Optimization of a mini-gamma camera based on a 2x2 array of Hamamatsu H8500 PSPMTs

    Energy Technology Data Exchange (ETDEWEB)

    Majewski, Stan [Jefferson Laboratory, 12000 Jefferson Ave., Newport News, VA 23606 (United States); Popov, Vladimir [Jefferson Laboratory, 12000 Jefferson Ave., Newport News, VA 23606 (United States); Wojcik, Randolph [Jefferson Laboratory, 12000 Jefferson Ave., Newport News, VA 23606 (United States): Ray Visions, Inc., 317 Blacksmith Arch, Yorktown, VA 23693 (United States)]. E-mail: wojcik@jlab.org; Weisenberger, Andrew [Jefferson Laboratory, 12000 Jefferson Ave., Newport News, VA 23606 (United States)

    2006-12-20

    We present the results of a comparative study between several scintillation sensors with the goal of optimizing the spatial resolution of a practical mini-gamma camera based on a 2x2 array of Hamamatsu H8500 flat panel position sensitive photomultiplier tubes (PSPMTs) with 64 anode pads per PSPMT. The readout of this 256 pad imager was achieved by a special in-house designed and optimized pad-decoupling strip readout reducing the number of readout channels to 32. Pixellated NaI(Tl) and CsI(Tl) scintillator arrays, as well as thin continuous GSO, GSOZ, CsI(Na) and CsI(Tl) scintillator plates were coupled to this PSPMT array to form a compact mini-gamma camera. This round of tests, following extensive prior experience with this type of imager, was intended to investigate the possibility of achieving an intrinsic spatial resolution of under 1.0 mm FWHM across the whole surface of the mini-gamma camera. We confirmed the results of our previous studies that the best overall performance is achieved with pixellated NaI(Tl) arrays. The present resolution limit attainable with the H8500 PSPMT array is approaching 1.2 mm FWHM, which is equivalent to the smallest available pixel pitch of these arrays.

  11. Study of a new architecture of gamma cameras with Cd/ZnTe/CdTe semiconductors; Etude d'une nouvelle architecture de gamma camera a base de semi-conducteurs CdZnTe /CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Guerin, L

    2007-11-15

    This thesis studies new semi conductors for gammas cameras in order to improve the quality of image in nuclear medicine. The chapter 1 reminds the general principle of the imaging gamma, by describing the radiotracers, the channel of detection and the types of Anger gamma cameras acquisition. The physiological, physical and technological limits of the camera are then highlighted, to better identify the needs of future gamma cameras. The chapter 2 is dedicated to a bibliographical study. At first, semi-conductors used in imaging gamma are presented, and more particularly semi-conductors CDTE and CdZnTe, by distinguishing planar detectors and monolithic pixelated detectors. Secondly, the classic collimators of the gamma cameras, used in clinical routine for the most part of between them, are described. Their geometry is presented, as well as their characteristics, their advantages and their inconveniences. The chapter 3 is dedicated to a state of art of the simulation codes dedicated to the medical imaging and the methods of reconstruction in imaging gamma. These states of art allow to introduce the software of simulation and the methods of reconstruction used within the framework of this thesis. The chapter 4 presents the new architecture of gamma camera proposed during this work of thesis. It is structured in three parts. The first part justifies the use of semiconducting detectors CdZnTe, in particular the monolithic pixelated detectors, by bringing to light their advantages with regard to the detection modules based on scintillator. The second part presents gamma cameras to base of detectors CdZnTe (prototypes or commercial products) and their associated collimators, as well as the interest of an association of detectors CdZnTe in the classic collimators. Finally, the third part presents in detail the HiSens architecture. The chapter 5 describes both software of simulation used within the framework of this thesis to estimate the performances of the Hi

  12. Performance evaluation of a small CZT pixelated semiconductor gamma camera system with a newly designed stack-up parallel-hole collimator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin [Department of Radiological Science, College of Health Science, Eulji University, 553 Sanseong-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-713 (Korea, Republic of); Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr [Department of Radiological Science, College of Health Science, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 220-710 (Korea, Republic of)

    2015-09-11

    Gamma ray imaging techniques that use a cadmium zinc telluride (CZT) or cadmium telluride (CdTe) pixelated semiconductor detectors have rapidly gained popularity as a key tool for nuclear medicine research. By using a pinhole collimator with a pixelated semiconductor gamma camera system, better spatial resolution can be achieved. However, this improvement in spatial resolution is accomplished with a decrease in the sensitivity due to the small collimator hole diameter. Furthermore, few studies have been conducted for novel parallel-hole collimator geometric designs with pixelated semiconductor gamma camera systems. A gamma camera system which combines a CZT pixelated semiconductor detector with a newly designed stack-up parallel-hole collimator was developed and evaluated. The eValuator-2500 CZT pixelated semiconductor detector (eV product, Saxonburg, PA) was selected for the gamma camera system. This detector consisted of a row of four CZT crystals of 12.8 mm in length with 3 mm in thickness. The proposed parallel-hole collimator consists of two layers. The upper layer results in a fourfold increase in hole size compared to a matched square hole parallel-hole collimator with an equal hole and pixel size, while the lower layer also consisted of fourfold holes size and pretty acts as a matched square hole parallel-hole collimator. The overlap ratios of these collimators were 1:1, 1:2, 2:1, 1:5, and 5:1. These collimators were mounted on the eValuator-2500 CZT pixelated semiconductor detector. The basic performance of the imaging system was measured for a {sup 57}Co gamma source (122 keV). The measured averages of sensitivity and spatial resolution varied depending on the overlap ratios of the proposed parallel-hole collimator and source-to-collimator distances. One advantage of our system is the use of stacked collimators that can select the best combination of system sensitivity and spatial resolution. With low counts, we can select a high sensitivity collimator

  13. A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

    Directory of Open Access Journals (Sweden)

    J. Mejia

    2010-12-01

    Full Text Available The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target’s three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology.

  14. A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mejia, J.; Galvis-Alonso, O.Y., E-mail: mejia_famerp@yahoo.com.b [Faculdade de Medicina de Sao Jose do Rio Preto (FAMERP), SP (Brazil). Dept. de Biologia Molecular; Castro, A.A. de; Simoes, M.V. [Faculdade de Medicina de Sao Jose do Rio Preto (FAMERP), SP (Brazil). Dept. de Clinica Medica; Leite, J.P. [Universidade de Sao Paulo (FMRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Medicina. Dept. de Neurociencias e Ciencias do Comportamento; Braga, J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Astrofisica

    2010-11-15

    The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target's three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT) system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology. (author)

  15. Monte Carlo simulations of compact gamma cameras based on avalanche photodiodes.

    Science.gov (United States)

    Després, Philippe; Funk, Tobias; Shah, Kanai S; Hasegawa, Bruce H

    2007-06-07

    Avalanche photodiodes (APDs), and in particular position-sensitive avalanche photodiodes (PSAPDs), are an attractive alternative to photomultiplier tubes (PMTs) for reading out scintillators for PET and SPECT. These solid-state devices offer high gain and quantum efficiency, and can potentially lead to more compact and robust imaging systems with improved spatial and energy resolution. In order to evaluate this performance improvement, we have conducted Monte Carlo simulations of gamma cameras based on avalanche photodiodes. Specifically, we investigated the relative merit of discrete and PSAPDs in a simple continuous crystal gamma camera. The simulated camera was composed of either a 4 x 4 array of four channels 8 x 8 mm2 PSAPDs or an 8 x 8 array of 4 x 4 mm2 discrete APDs. These configurations, requiring 64 channels readout each, were used to read the scintillation light from a 6 mm thick continuous CsI:Tl crystal covering the entire 3.6 x 3.6 cm2 photodiode array. The simulations, conducted with GEANT4, accounted for the optical properties of the materials, the noise characteristics of the photodiodes and the nonlinear charge division in PSAPDs. The performance of the simulated camera was evaluated in terms of spatial resolution, energy resolution and spatial uniformity at 99mTc (140 keV) and 125I ( approximately 30 keV) energies. Intrinsic spatial resolutions of 1.0 and 0.9 mm were obtained for the APD- and PSAPD-based cameras respectively for 99mTc, and corresponding values of 1.2 and 1.3 mm FWHM for 125I. The simulations yielded maximal energy resolutions of 7% and 23% for 99mTc and 125I, respectively. PSAPDs also provided better spatial uniformity than APDs in the simple system studied. These results suggest that APDs constitute an attractive technology especially suitable to build compact, small field of view gamma cameras dedicated, for example, to small animal or organ imaging.

  16. Evaluation of list-mode ordered subset expectation maximization image reconstruction for pixelated solid-state compton gamma camera with large number of channels

    Science.gov (United States)

    Kolstein, M.; De Lorenzo, G.; Chmeissani, M.

    2014-04-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated solid-state technology for nuclear medicine applications. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). For Compton camera, especially with a large number of readout channels, image reconstruction presents a big challenge. In this work, results are presented for the List-Mode Ordered Subset Expectation Maximization (LM-OSEM) image reconstruction algorithm on simulated data with the VIP Compton camera design. For the simulation, all realistic contributions to the spatial resolution are taken into account, including the Doppler broadening effect. The results show that even with a straightforward implementation of LM-OSEM, good images can be obtained for the proposed Compton camera design. Results are shown for various phantoms, including extended sources and with a distance between the field of view and the first detector plane equal to 100 mm which corresponds to a realistic nuclear medicine environment.

  17. Imaging performance comparison between a LaBr3: Ce scintillator based and a CdTe semiconductor based photon counting compact gamma camera.

    Science.gov (United States)

    Russo, P; Mettivier, G; Pani, R; Pellegrini, R; Cinti, M N; Bennati, P

    2009-04-01

    The authors report on the performance of two small field of view, compact gamma cameras working in single photon counting in planar imaging tests at 122 and 140 keV. The first camera is based on a LaBr3: Ce scintillator continuous crystal (49 x 49 x 5 mm3) assembled with a flat panel multianode photomultiplier tube with parallel readout. The second one belongs to the class of semiconductor hybrid pixel detectors, specifically, a CdTe pixel detector (14 x 14 x 1 mm3) with 256 x 256 square pixels and a pitch of 55 microm, read out by a CMOS single photon counting integrated circuit of the Medipix2 series. The scintillation camera was operated with selectable energy window while the CdTe camera was operated with a single low-energy detection threshold of about 20 keV, i.e., without energy discrimination. The detectors were coupled to pinhole or parallel-hole high-resolution collimators. The evaluation of their overall performance in basic imaging tasks is presented through measurements of their detection efficiency, intrinsic spatial resolution, noise, image SNR, and contrast recovery. The scintillation and CdTe cameras showed, respectively, detection efficiencies at 122 keV of 83% and 45%, intrinsic spatial resolutions of 0.9 mm and 75 microm, and total background noises of 40.5 and 1.6 cps. Imaging tests with high-resolution parallel-hole and pinhole collimators are also reported.

  18. MO-AB-206-02: Testing Gamma Cameras Based On TG177 WG Report.

    Science.gov (United States)

    Halama, J

    2016-06-01

    This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described.

  19. Development and Characterization of a Round Hand-Held Silicon Photomultiplier Based Gamma Camera for Intraoperative Imaging

    Science.gov (United States)

    Popovic, Kosta; McKisson, Jack E.; Kross, Brian; Lee, Seungjoon; McKisson, John; Weisenberger, Andrew G.; Proffitt, James; Stolin, Alexander; Majewski, Stan; Williams, Mark B.

    2014-06-01

    This paper describes the development of a hand-held gamma camera for intraoperative surgical guidance that is based on silicon photomultiplier (SiPM) technology. The camera incorporates a cerium doped lanthanum bromide ( LaBr3:Ce) plate scintillator, an array of 80 SiPM photodetectors and a two-layer parallel-hole collimator. The field of view is circular with a 60 mm diameter. The disk-shaped camera housing is 75 mm in diameter, approximately 40.5 mm thick and has a mass of only 1.4 kg, permitting either hand-held or arm-mounted use. All camera components are integrated on a mobile cart that allows easy transport. The camera was developed for use in surgical procedures, including determination of the location and extent of primary carcinomas, detection of secondary lesions, and sentinel lymph node biopsy (SLNB). Here, we describe the camera design and its principal operating characteristics, including spatial resolution, energy resolution, sensitivity uniformity, and geometric linearity. The gamma camera has an intrinsic spatial resolution of 4.2 mm FWHM, an energy resolution of 21.1% FWHM at 140 keV, and a sensitivity of 481 and 73 cps/MBq when using the single- and double-layer collimators, respectively.

  20. Development and characterization of a round hand-held silicon photomultiplier based gamma camera for intraoperative imaging

    Science.gov (United States)

    Popovic, Kosta; McKisson, Jack E.; Kross, Brian; Lee, Seungjoon; McKisson, John; Weisenberger, Andrew G.; Proffitt, James; Stolin, Alexander; Majewski, Stan; Williams, Mark B.

    2017-01-01

    This paper describes the development of a hand-held gamma camera for intraoperative surgical guidance that is based on silicon photomultiplier (SiPM) technology. The camera incorporates a cerium doped lanthanum bromide (LaBr3:Ce) plate scintillator, an array of 80 SiPM photodetectors and a two-layer parallel-hole collimator. The field of view is circular with a 60 mm diameter. The disk-shaped camera housing is 75 mm in diameter, approximately 40.5 mm thick and has a mass of only 1.4 kg, permitting either hand-held or arm-mounted use. All camera components are integrated on a mobile cart that allows easy transport. The camera was developed for use in surgical procedures including determination of the location and extent of primary carcinomas, detection of secondary lesions and sentinel lymph node biopsy (SLNB). Here we describe the camera design and its principal operating characteristics, including spatial resolution, energy resolution, sensitivity uniformity, and geometric linearity. The gamma camera has an intrinsic spatial resolution of 4.2 mm FWHM, an energy resolution of 21.1 % FWHM at 140 keV, and a sensitivity of 481 and 73 cps/MBq when using the single- and double-layer collimators, respectively. PMID:28286345

  1. COMPACT CdZnTe-BASED GAMMA CAMERA FOR PROSTATE CANCER IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    CUI, Y.; LALL, T.; TSUI, B.; YU, J.; MAHLER, G.; BOLOTNIKOV, A.; VASKA, P.; DeGERONIMO, G.; O' CONNOR, P.; MEINKEN, G.; JOYAL, J.; BARRETT, J.; CAMARDA, G.; HOSSAIN, A.; KIM, K.H.; YANG, G.; POMPER, M.; CHO, S.; WEISMAN, K.; SEO, Y.; BABICH, J.; LaFRANCE, N.; AND JAMES, R.B.

    2011-10-23

    In this paper, we discuss the design of a compact gamma camera for high-resolution prostate cancer imaging using Cadmium Zinc Telluride (CdZnTe or CZT) radiation detectors. Prostate cancer is a common disease in men. Nowadays, a blood test measuring the level of prostate specific antigen (PSA) is widely used for screening for the disease in males over 50, followed by (ultrasound) imaging-guided biopsy. However, PSA tests have a high false-positive rate and ultrasound-guided biopsy has a high likelihood of missing small cancerous tissues. Commercial methods of nuclear medical imaging, e.g. PET and SPECT, can functionally image the organs, and potentially find cancer tissues at early stages, but their applications in diagnosing prostate cancer has been limited by the smallness of the prostate gland and the long working distance between the organ and the detectors comprising these imaging systems. CZT is a semiconductor material with wide band-gap and relatively high electron mobility, and thus can operate at room temperature without additional cooling. CZT detectors are photon-electron direct-conversion devices, thus offering high energy-resolution in detecting gamma rays, enabling energy-resolved imaging, and reducing the background of Compton-scattering events. In addition, CZT material has high stopping power for gamma rays; for medical imaging, a few-mm-thick CZT material provides adequate detection efficiency for many SPECT radiotracers. Because of these advantages, CZT detectors are becoming popular for several SPECT medical-imaging applications. Most recently, we designed a compact gamma camera using CZT detectors coupled to an application-specific-integrated-circuit (ASIC). This camera functions as a trans-rectal probe to image the prostate gland from a distance of only 1-5 cm, thus offering higher detection efficiency and higher spatial resolution. Hence, it potentially can detect prostate cancers at their early stages. The performance tests of this camera

  2. Compact CdZnTe-based gamma camera for prostate cancer imaging

    Science.gov (United States)

    Cui, Yonggang; Lall, Terry; Tsui, Benjamin; Yu, Jianhua; Mahler, George; Bolotnikov, Aleksey; Vaska, Paul; De Geronimo, Gianluigi; O'Connor, Paul; Meinken, George; Joyal, John; Barrett, John; Camarda, Giuseppe; Hossain, Anwar; Kim, Ki Hyun; Yang, Ge; Pomper, Marty; Cho, Steve; Weisman, Ken; Seo, Youngho; Babich, John; LaFrance, Norman; James, Ralph B.

    2011-06-01

    In this paper, we discuss the design of a compact gamma camera for high-resolution prostate cancer imaging using Cadmium Zinc Telluride (CdZnTe or CZT) radiation detectors. Prostate cancer is a common disease in men. Nowadays, a blood test measuring the level of prostate specific antigen (PSA) is widely used for screening for the disease in males over 50, followed by (ultrasound) imaging-guided biopsy. However, PSA tests have a high falsepositive rate and ultrasound-guided biopsy has a high likelihood of missing small cancerous tissues. Commercial methods of nuclear medical imaging, e.g. PET and SPECT, can functionally image the organs, and potentially find cancer tissues at early stages, but their applications in diagnosing prostate cancer has been limited by the smallness of the prostate gland and the long working distance between the organ and the detectors comprising these imaging systems. CZT is a semiconductor material with wide band-gap and relatively high electron mobility, and thus can operate at room temperature without additional cooling. CZT detectors are photon-electron direct-conversion devices, thus offering high energy-resolution in detecting gamma rays, enabling energy-resolved imaging, and reducing the background of Compton-scattering events. In addition, CZT material has high stopping power for gamma rays; for medical imaging, a few-mm-thick CZT material provides adequate detection efficiency for many SPECT radiotracers. Because of these advantages, CZT detectors are becoming popular for several SPECT medical-imaging applications. Most recently, we designed a compact gamma camera using CZT detectors coupled to an application-specific-integratedcircuit (ASIC). This camera functions as a trans-rectal probe to image the prostate gland from a distance of only 1-5 cm, thus offering higher detection efficiency and higher spatial resolution. Hence, it potentially can detect prostate cancers at their early stages. The performance tests of this camera

  3. Monitoring system for isolated limb perfusion based on a portable gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Orero, A.; Muxi, A.; Rubi, S.; Duch, J. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); Vidal-Sicart, S.; Pons, F. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); Inst. d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona (Spain); Red Tematica de Investigacion Cooperativa en Cancer (RTICC), Barcelona (Spain); Roe, N. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); CIBER de Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona (Spain); Rull, R. [Servei de Cirurgia, Hospital Clinic, Barcelona (Spain); Pavon, N. [Inst. de Fisica Corpuscular, CSIC - UV, Valencia (Spain); Pavia, J. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); Inst. d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona (Spain); CIBER de Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona (Spain)

    2009-07-01

    Background: The treatment of malignant melanoma or sarcomas on a limb using extremity perfusion with tumour necrosis factor (TNF-{alpha}) and melphalan can result in a high degree of systemic toxicity if there is any leakage from the isolated blood territory of the limb into the systemic vascular territory. Leakage is currently controlled by using radiotracers and heavy external probes in a procedure that requires continuous manual calculations. The aim of this work was to develop a light, easily transportable system to monitor limb perfusion leakage by controlling systemic blood pool radioactivity with a portable gamma camera adapted for intraoperative use as an external probe, and to initiate its application in the treatment of MM patients. Methods: A special collimator was built for maximal sensitivity. Software for acquisition and data processing in real time was developed. After testing the adequacy of the system, it was used to monitor limb perfusion leakage in 16 patients with malignant melanoma to be treated with perfusion of TNF-{alpha} and melphalan. Results: The field of view of the detector system was 13.8 cm, which is appropriate for the monitoring, since the area to be controlled was the precordial zone. The sensitivity of the system was 257 cps/MBq. When the percentage of leakage reaches 10% the associated absolute error is {+-}1%. After a mean follow-up period of 12 months, no patients have shown any significant or lasting side-effects. Partial or complete remission of lesions was seen in 9 out of 16 patients (56%) after HILP with TNF-{alpha} and melphalan. Conclusion: The detector system together with specially developed software provides a suitable automatic continuous monitoring system of any leakage that may occur during limb perfusion. This technique has been successfully implemented in patients for whom perfusion with TNF-{alpha} and melphalan has been indicated. (orig.)

  4. The influence of electron multiplication and internal X-ray fluorescence on the performance of a scintillator-based gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Hall, David J., E-mail: d.j.hall@open.ac.uk [e2v centre for electronic imaging, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Holland, Andrew; Soman, Matthew [e2v centre for electronic imaging, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2012-06-21

    When considering the 'standard' gamma-camera, one might picture an array of photo-multiplier tubes or a similar array of small-area detectors. This array of imaging detectors would be attached to a corresponding array of scintillator modules (or a solid layer of scintillator) in order to give a high detection efficiency in the energy region of interest, usually 8-140 keV. Over recent years, developments of gamma-cameras capable of achieving much higher spatial resolutions have led to a new range of systems based on Charge-Coupled Devices with some form of signal multiplication between the scintillator and the CCD in order for one to distinguish the light output from the scintillator above the CCD noise. The use of an Electron-Multiplying Charge-Coupled Device (EM-CCD) incorporates the gain process within the CCD through a form of 'impact ionisation', however, the gain process introduces an 'excess noise factor' due to the probabilistic nature of impact ionisation and this additional noise consequently has an impact on the spatial and spectral resolution of the detector. Internal fluorescence in the scintillator, producing K-shell X-ray fluorescence photons that can be detected alongside the incident gamma-rays, also has a major impact on the imaging capabilities of gamma-cameras. This impact varies dramatically from the low spatial resolution to high spatial resolution camera system. Through a process of simulation and experimental testing focussed on the high spatial resolution (EM-CCD based) variant, the factors affecting the performance of gamma-camera systems are discussed and the results lead to important conclusions to be considered for the development of future systems. This paper presents a study into the influence of the EM-CCD gain process and the internal X-ray fluorescence in the scintillator on the performance of scintillator-based gamma cameras (CCD-based or otherwise), making use of Monte Carlo simulations to demonstrate

  5. Development of event reconstruction algorithm for full-body gamma-camera based on SiPMs

    Science.gov (United States)

    Philippov, D. E.; Belyaev, V. N.; Buzhan, P. Zh; Ilyin, A. L.; Popova, E. V.; Stifutkin, A. A.

    2016-02-01

    The gamma-camera is the detector for nuclear medical imaging where the photomultiplier tubes (PMTs) could be replaced by the silicon photomultipliers (SiPMs). Common systems have the energy resolution about 10% and intrinsic spatial resolution about 3 mm (FWHM). In order to achieve the requirement energy and spatial resolution the classical Anger's logic should be modified. In case of a standard monolithic thallium activated sodium iodide scintillator (500x400x10 mm3) and SiPM readout it could be done with identification of the clusters. We show that this approach has a good results with the simulated data.

  6. A novel fully integrated handheld gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Massari, R.; Ucci, A.; Campisi, C. [Biostructure and Bioimaging Institute (IBB), National Research Council of Italy (CNR), Rome (Italy); Scopinaro, F. [University of Rome “La Sapienza”, S. Andrea Hospital, Rome (Italy); Soluri, A., E-mail: alessandro.soluri@ibb.cnr.it [Biostructure and Bioimaging Institute (IBB), National Research Council of Italy (CNR), Rome (Italy)

    2016-10-01

    In this paper, we present an innovative, fully integrated handheld gamma camera, namely designed to gather in the same device the gamma ray detector with the display and the embedded computing system. The low power consumption allows the prototype to be battery operated. To be useful in radioguided surgery, an intraoperative gamma camera must be very easy to handle since it must be moved to find a suitable view. Consequently, we have developed the first prototype of a fully integrated, compact and lightweight gamma camera for radiopharmaceuticals fast imaging. The device can operate without cables across the sterile field, so it may be easily used in the operating theater for radioguided surgery. The prototype proposed consists of a Silicon Photomultiplier (SiPM) array coupled with a proprietary scintillation structure based on CsI(Tl) crystals. To read the SiPM output signals, we have developed a very low power readout electronics and a dedicated analog to digital conversion system. One of the most critical aspects we faced designing the prototype was the low power consumption, which is mandatory to develop a battery operated device. We have applied this detection device in the lymphoscintigraphy technique (sentinel lymph node mapping) comparing the results obtained with those of a commercial gamma camera (Philips SKYLight). The results obtained confirm a rapid response of the device and an adequate spatial resolution for the use in the scintigraphic imaging. This work confirms the feasibility of a small gamma camera with an integrated display. This device is designed for radioguided surgery and small organ imaging, but it could be easily combined into surgical navigation systems.

  7. Spectroscopic gamma camera for use in high dose environments

    Science.gov (United States)

    Ueno, Yuichiro; Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi; Fujishima, Yasutake; Kometani, Yutaka; Suzuki, Yasuhiko; Umegaki, Kikuo

    2016-06-01

    We developed a pinhole gamma camera to measure distributions of radioactive material contaminants and to identify radionuclides in extraordinarily high dose regions (1000 mSv/h). The developed gamma camera is characterized by: (1) tolerance for high dose rate environments; (2) high spatial and spectral resolution for identifying unknown contaminating sources; and (3) good usability for being carried on a robot and remotely controlled. These are achieved by using a compact pixelated detector module with CdTe semiconductors, efficient shielding, and a fine resolution pinhole collimator. The gamma camera weighs less than 100 kg, and its field of view is an 8 m square in the case of a distance of 10 m and its image is divided into 256 (16×16) pixels. From the laboratory test, we found the energy resolution at the 662 keV photopeak was 2.3% FWHM, which is enough to identify the radionuclides. We found that the count rate per background dose rate was 220 cps h/mSv and the maximum count rate was 300 kcps, so the maximum dose rate of the environment where the gamma camera can be operated was calculated as 1400 mSv/h. We investigated the reactor building of Unit 1 at the Fukushima Dai-ichi Nuclear Power Plant using the gamma camera and could identify the unknown contaminating source in the dose rate environment that was as high as 659 mSv/h.

  8. Spectroscopic gamma camera for use in high dose environments

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Yuichiro, E-mail: yuichiro.ueno.bv@hitachi.com [Research and Development Group, Hitachi, Ltd., Hitachi-shi, Ibaraki-ken 319-1221 (Japan); Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi [Research and Development Group, Hitachi, Ltd., Hitachi-shi, Ibaraki-ken 319-1221 (Japan); Fujishima, Yasutake; Kometani, Yutaka [Hitachi Works, Hitachi-GE Nuclear Energy, Ltd., Hitachi-shi, Ibaraki-ken (Japan); Suzuki, Yasuhiko [Measuring Systems Engineering Dept., Hitachi Aloka Medical, Ltd., Ome-shi, Tokyo (Japan); Umegaki, Kikuo [Faculty of Engineering, Hokkaido University, Sapporo-shi, Hokkaido (Japan)

    2016-06-21

    We developed a pinhole gamma camera to measure distributions of radioactive material contaminants and to identify radionuclides in extraordinarily high dose regions (1000 mSv/h). The developed gamma camera is characterized by: (1) tolerance for high dose rate environments; (2) high spatial and spectral resolution for identifying unknown contaminating sources; and (3) good usability for being carried on a robot and remotely controlled. These are achieved by using a compact pixelated detector module with CdTe semiconductors, efficient shielding, and a fine resolution pinhole collimator. The gamma camera weighs less than 100 kg, and its field of view is an 8 m square in the case of a distance of 10 m and its image is divided into 256 (16×16) pixels. From the laboratory test, we found the energy resolution at the 662 keV photopeak was 2.3% FWHM, which is enough to identify the radionuclides. We found that the count rate per background dose rate was 220 cps h/mSv and the maximum count rate was 300 kcps, so the maximum dose rate of the environment where the gamma camera can be operated was calculated as 1400 mSv/h. We investigated the reactor building of Unit 1 at the Fukushima Dai-ichi Nuclear Power Plant using the gamma camera and could identify the unknown contaminating source in the dose rate environment that was as high as 659 mSv/h.

  9. Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

    Science.gov (United States)

    Dai, Qiu-Sheng; Zhao, Cui-Lan; Zhang, Hua-Lin; Qi, Yu-Jin

    2010-08-01

    The objective of this study is to investigate a high performance and lower cost compact gamma camera module for a multi-head small animal SPECT system. A compact camera module was developed using a thin Lutetium Oxyorthosilicate (LSO) scintillation crystal slice coupled to a Hamamatsu H8500 position sensitive photomultiplier tube (PSPMT). A two-stage charge division readout board based on a novel sub-tractive resistive readout with a truncated center-of-gravity (TCOG) positioning method was developed for the camera. The performance of the camera was evaluated using a flood 99mTc source with a four-quadrant bar-mask phantom. The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor. The response output area (ROA) of the camera shown in the flood image was improved up to 34%, and an intrinsic spatial resolution better than 2 mm of detector was achieved. In conclusion, the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.

  10. A new design for a high resolution, high efficiency CZT gamma camera detector

    Science.gov (United States)

    Mestais, C.; Baffert, N.; Bonnefoy, J. P.; Chapuis, A.; Koenig, A.; Monnet, O.; Ouvrier Buffet, P.; Rostaing, J. P.; Sauvage, F.; Verger, L.

    2001-02-01

    We have designed a CZT gamma camera detector that provides an array of CZT pixels and associated front-end electronics - including an ASIC - and permits gamma camera measurements using the method patented by CEA-LETI and reported by Verger et al. [1]. Electron response in each CZT pixel is registered by correcting pulse height for position of interaction based on fast rise-time information. This method brings advantages of high scatter rejection while allowing high detection efficiency. These techniques and the systems approach have been developed at CEA-LETI in an exclusive joint development with BICRON and CRISMATEC who in turn are commercializing the technology. The initial system is implemented in an array framework with 1920 pixels, approximately 180×215 mm 2 in dimension, but the system architecture expands readily to 4096 pixels, and these arrays can be ganged into groups of up to 8 for pixel planes totaling over 32 000 pixels without architecture changes. The overall system design is described and brain phantom images are presented that were obtained by scanning with a small number of pixels.

  11. Acceptance of gamma camera Philips bright view based in the protocol nema 2001; Aceptacion de gammacamara philips brightview basada en el protocolo nema 2001

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer Gracia, C.; Luquero Llopis, N.; Plaza Aparicio, R.; Huerga Cabrerizo, C.; Corredoira Silva, E.; Serrada Hierro, A.

    2013-07-01

    Recently a new Philips Bright View X gamma camera installed in the Nuclear Medicine Service. It is one gamma camera of nuclear medicine of variable angle with double detector that can be configured for cardiac SPECT, SPECT not circular, body full, dynamic planar and several acquisitions with a single detector. (Author)

  12. Evaluation of efficiency of a semiconductor gamma camera

    CERN Document Server

    Otake, H; Takeuchi, Y

    2002-01-01

    We evaluation basic characteristics of a compact type semiconductor gamma camera (eZ-SCOPE AN) of Cadmium Zinc Telluride (CdZnTe). This new compact gamma camera has 256 semiconductors representing the same number of pixels. Each semiconductor is 2 mm square and is located in 16 lines and rows on the surface of the detector. The specific performance characteristics were evaluated in the study referring to National Electrical Manufactures Association (NEMA) standards; intrinsic energy resolution, intrinsic count rate performance, integral uniformity, system planar sensitivity, system spatial resolution, and noise to the neighboring pixels. The intrinsic energy resolution measured 5.7% as full width half maximum (FWHM). The intrinsic count rate performance ranging from 17 kcps to 1,285 kcps was evaluated, but the highest intrinsic count rate was not observed. Twenty percents count loss was recognized at 1,021 kcps. The integral uniformity was 1.3% with high sensitivity collimator. The system planar sensitivity w...

  13. A scheme for assessing the performance characteristics of small field-of-view gamma cameras.

    Science.gov (United States)

    Bhatia, B S; Bugby, S L; Lees, J E; Perkins, A C

    2015-02-01

    Existing protocols for assessing the performance characteristics of large field-of-view (LFOV) gamma cameras can be inappropriate and require modification for use with small field-of-view (SFOV) gamma camera systems. This communication proposes a generic scheme suitable for evaluating the performance characteristics of SFOV gamma cameras, based on modifications to the standard procedures of NEMA NU1-2007. Key differences in methodology between tests for LFOV and SFOV gamma cameras are highlighted along with the rationale for these changes. It is envisaged that this scheme will provide more appropriate methods for equipment characterisation, ensuring quality and consistency for all SFOV cameras.

  14. Development of a high resolution gamma camera system using finely grooved GAGG scintillator

    Science.gov (United States)

    Yamamoto, Seiichi; Kataoka, Jun; Oshima, Tsubasa; Ogata, Yoshimune; Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Hatazawa, Jun

    2016-06-01

    High resolution gamma cameras require small pixel scintillator blocks with high light output. However, manufacturing a small pixel scintillator block is difficult when the pixel size becomes small. To solve this limitation, we developed a high resolution gamma camera system using a finely grooved Ce-doped Gd3Al2Ga3O12 (GAGG) plate. Our gamma camera's detector consists of a 1-mm-thick finely grooved GAGG plate that is optically coupled to a 1-in. position sensitive photomultiplier tube (PSPMT). The grooved GAGG plate has 0.2×0.2 mm pixels with 0.05-mm wide slits (between the pixels) that were manufactured using a dicing saw. We used a Hamamatsu PSPMT with a 1-in. square high quantum efficiency (HQE) PSPMT (R8900-100-C12). The energy resolution for the Co-57 gamma photons (122 keV) was 18.5% FWHM. The intrinsic spatial resolution was estimated to be 0.7-mm FWHM. With a 0.5-mm diameter pinhole collimator mounted to its front, we achieved a high resolution, small field-of-view gamma camera. The system spatial resolution for the Co-57 gamma photons was 1.0-mm FWHM, and the sensitivity was 0.0025%, 10 mm from the collimator surface. The Tc-99m HMDP administered mouse images showed the fine structures of the mouse body's parts. Our developed high resolution small pixel GAGG gamma camera is promising for such small animal imaging.

  15. Nuclear probes and intraoperative gamma cameras.

    Science.gov (United States)

    Heller, Sherman; Zanzonico, Pat

    2011-05-01

    Gamma probes are now an important, well-established technology in the management of cancer, particularly in the detection of sentinel lymph nodes. Intraoperative sentinel lymph node as well as tumor detection may be improved under some circumstances by the use of beta (negatron or positron), rather than gamma detection, because the very short range (∼ 1 mm or less) of such particulate radiations eliminates the contribution of confounding counts from activity other than in the immediate vicinity of the detector. This has led to the development of intraoperative beta probes. Gamma camera imaging also benefits from short source-to-detector distances and minimal overlying tissue, and intraoperative small field-of-view gamma cameras have therefore been developed as well. Radiation detectors for intraoperative probes can generally be characterized as either scintillation or ionization detectors. Scintillators used in scintillation-detector probes include thallium-doped sodium iodide, thallium- and sodium-doped cesium iodide, and cerium-doped lutecium orthooxysilicate. Alternatives to inorganic scintillators are plastic scintillators, solutions of organic scintillation compounds dissolved in an organic solvent that is subsequently polymerized to form a solid. Their combined high counting efficiency for beta particles and low counting efficiency for 511-keV annihilation γ-rays make plastic scintillators well-suited as intraoperative beta probes in general and positron probes in particular Semiconductors used in ionization-detector probes include cadmium telluride, cadmium zinc telluride, and mercuric iodide. Clinical studies directly comparing scintillation and semiconductor intraoperative probes have not provided a clear choice between scintillation and ionization detector-based probes. The earliest small field-of-view intraoperative gamma camera systems were hand-held devices having fields of view of only 1.5-2.5 cm in diameter that used conventional thallium

  16. Portable mini gamma camera for medical applications

    CERN Document Server

    Porras, E; Benlloch, J M; El-Djalil-Kadi-Hanifi, M; López, S; Pavon, N; Ruiz, J A; Sánchez, F; Sebastiá, A

    2002-01-01

    A small, portable and low-cost gamma camera for medical applications has been developed and clinically tested. This camera, based on a scintillator crystal and a Position Sensitive Photo-Multiplier Tube, has a useful field of view of 4.6 cm diameter and provides 2.2 mm of intrinsic spatial resolution. Its mobility and light weight allow to reach the patient from any desired direction. This camera images small organs with high efficiency and so addresses the demand for devices of specific clinical applications. In this paper, we present the camera and briefly describe the procedures that have led us to choose its configuration and the image reconstruction method. The clinical tests and diagnostic capability are also presented and discussed.

  17. Myocardial perfusion imaging with a cadmium zinc telluride-based gamma camera versus invasive fractional flow reserve

    Energy Technology Data Exchange (ETDEWEB)

    Mouden, Mohamed [Isala klinieken, Department of Cardiology, Zwolle (Netherlands); Isala klinieken, Department of Nuclear Medicine, Zwolle (Netherlands); Ottervanger, Jan Paul; Timmer, Jorik R. [Isala klinieken, Department of Cardiology, Zwolle (Netherlands); Knollema, Siert; Reiffers, Stoffer; Oostdijk, Ad H.J.; Jager, Pieter L. [Isala klinieken, Department of Nuclear Medicine, Zwolle (Netherlands); Boer, Menko-Jan de [University Medical Centre Nijmegen, Department of Cardiology, Nijmegen (Netherlands)

    2014-05-15

    Recently introduced ultrafast cardiac SPECT cameras with cadmium zinc telluride-based (CZT) detectors may provide superior image quality allowing faster acquisition with reduced radiation doses. Although the level of concordance between conventional SPECT and invasive fractional flow reserve (FFR) measurement has been studied, that between FFR and CZT-based SPECT is not yet known. Therefore, we aimed to assess the level of concordance between CZT SPECT and FFR in a large patient group with stable coronary artery disease. Both invasive FFR and myocardial perfusion imaging with a CZT-based SPECT camera, using Tc-tetrofosmin as tracer, were performed in 100 patients with stable angina and intermediate grade stenosis on invasive coronary angiography. A cut-off value of <0.75 was used to define abnormal FFR. The mean age of the patients was 64 ± 11 years, and 64 % were men. SPECT demonstrated ischaemia in 31 % of the patients, and 20 % had FFR <0.75. The concordance between CZT SPECT and FFR was 73 % on a per-patient basis and 79 % on a per-vessel basis. Discordant findings were more often seen in older patients and were mainly (19 %) the result of ischaemic SPECT findings in patients with FFR ≥0.75, whereas only 8 % had an abnormal FFR without ischaemia as demonstrated by CZT SPECT. Only 20 - 30 % of patients with intermediate coronary stenoses had significant ischaemia as assessed by CZT SPECT or invasive FFR. CZT SPECT showed a modest degree of concordance with FFR, which is comparable with previous results with conventional SPECT. Further investigations are particularly necessary in patients with normal SPECT and abnormal FFR, especially to determine whether these patients should undergo revascularization. (orig.)

  18. TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Marie-Paule, E-mail: marie-paule.garcia@univ-brest.fr; Villoing, Daphnée [UMR 1037 INSERM/UPS, CRCT, 133 Route de Narbonne, 31062 Toulouse (France); McKay, Erin [St George Hospital, Gray Street, Kogarah, New South Wales 2217 (Australia); Ferrer, Ludovic [ICO René Gauducheau, Boulevard Jacques Monod, St Herblain 44805 (France); Cremonesi, Marta; Botta, Francesca; Ferrari, Mahila [European Institute of Oncology, Via Ripamonti 435, Milano 20141 (Italy); Bardiès, Manuel [UMR 1037 INSERM/UPS, CRCT, 133 Route de Narbonne, Toulouse 31062 (France)

    2015-12-15

    Purpose: The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. Methods: The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of a given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit GATE offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on GATE to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user’s imaging requirements and generates automatically command files used as input for GATE. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant GATE input files are generated for the virtual patient model and associated pharmacokinetics. Results: Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body “step and shoot” acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry

  19. New gamma cameras in nuclear cardiology: D-SPECT; Les nouvelles gamma cameras en cardiologie nucleaire: D-Spect

    Energy Technology Data Exchange (ETDEWEB)

    Rouzet, F.; Bechara, T.; Ben Ali, K.; Nassar, P.; Grellier, J.F.; Burg, S.; Hyafil, F.; Le Guludec, D. [Service de medecine nucleaire, groupe hospitalier Bichat-Claude-Bernard, AP-HP, 75 - Paris (France)

    2010-08-15

    Over the past few years, advances in nuclear medicine aimed at decreasing both the duration and dosimetry of exams, without decreasing image quality. In this setting, Spectrum Dynamics (D-Spect) is a new generation gamma camera dedicated to cardiac scintigraphy. Its technology includes solid-state detectors based on pixelated semiconductors, region-centric (cardiac area) scanning, high-sensitivity collimators and resolution recovery. An additional particularity is the patient position during scanning. Phantom studies showed an improvement of sensitivity compared to conventional cameras, at the price of a loss in geometric resolution, which is compensated by resolution recovery. Semiconductors detectors provide a better energy resolution than conventional detectors suited to double isotope acquisitions, and a high count rate allowing dynamic acquisitions. Only few clinical studies are available so far, they suggest performances similar to that of conventional cameras obtained with acquisitions duration reduced to few minutes. The next step is to establish a trade-off between acquisition duration and dosimetry reduction. (authors)

  20. Initial evaluation of a modified dual-energy window scatter correction method for CZT-based gamma cameras for breast SPECT

    Science.gov (United States)

    Mann, Steve D.; Tornai, Martin P.

    2015-03-01

    Solid state Cadmium Zinc Telluride (CZT) gamma cameras for SPECT imaging offer significantly improved energy resolution compared to traditional scintillation detectors. However, the photopeak resolution is often asymmetric due to incomplete charge collection within the detector, resulting in many photopeak events incorrectly sorted into lower energy bins ("tailing"). These misplaced events contaminate the true scatter signal, which may negatively impact scatter correction methods that rely on estimates of scatter from the spectra. Additionally, because CZT detectors are organized into arrays, each individual detector element may exhibit different degrees of tailing. Here, we present a modified dualenergy window scatter correction method for emission detection and imaging that attempts to account for positiondependent effects of incomplete charge collection in the CZT gamma camera of our dedicated breast SPECT-CT system. Point source measurements and geometric phantoms were used to estimate the impact of tailing on the scatter signal and extract a better estimate of the ratio of scatter within two energy windows. To evaluate the method, cylindrical phantoms with and without a separate fillable chamber were scanned to determine the impact on quantification in hot, cold, and uniform background regions. Projections were reconstructed using OSEM, and the results for the traditional and modified scatter correction methods were compared. Results show that while modest reduced quantification accuracy was observed in hot and cold regions of the multi-chamber phantoms, the modified scatter correction method yields up to 8% improved quantification accuracy with 4% less added noise than the traditional DEW method within uniform background regions.

  1. Development of a high resolution gamma camera system using finely grooved GAGG scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Kataoka, Jun; Oshima, Tsubasa [Research Institute for Science and Engineering, Waseda University (Japan); Ogata, Yoshimune [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Hatazawa, Jun [Osaka University Graduate School of Medicine (Japan)

    2016-06-11

    High resolution gamma cameras require small pixel scintillator blocks with high light output. However, manufacturing a small pixel scintillator block is difficult when the pixel size becomes small. To solve this limitation, we developed a high resolution gamma camera system using a finely grooved Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (GAGG) plate. Our gamma camera's detector consists of a 1-mm-thick finely grooved GAGG plate that is optically coupled to a 1-in. position sensitive photomultiplier tube (PSPMT). The grooved GAGG plate has 0.2×0.2 mm pixels with 0.05-mm wide slits (between the pixels) that were manufactured using a dicing saw. We used a Hamamatsu PSPMT with a 1-in. square high quantum efficiency (HQE) PSPMT (R8900-100-C12). The energy resolution for the Co-57 gamma photons (122 keV) was 18.5% FWHM. The intrinsic spatial resolution was estimated to be 0.7-mm FWHM. With a 0.5-mm diameter pinhole collimator mounted to its front, we achieved a high resolution, small field-of-view gamma camera. The system spatial resolution for the Co-57 gamma photons was 1.0-mm FWHM, and the sensitivity was 0.0025%, 10 mm from the collimator surface. The Tc-99m HMDP administered mouse images showed the fine structures of the mouse body's parts. Our developed high resolution small pixel GAGG gamma camera is promising for such small animal imaging.

  2. 21 CFR 892.1100 - Scintillation (gamma) camera.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scintillation (gamma) camera. 892.1100 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1100 Scintillation (gamma) camera. (a) Identification. A scintillation (gamma) camera is a device intended to image the distribution of radionuclides...

  3. Gamma camera performance: technical assessment protocol

    Energy Technology Data Exchange (ETDEWEB)

    Bolster, A.A. [West Glasgow Hospitals NHS Trust, London (United Kingdom). Dept. of Clinical Physics; Waddington, W.A. [University College London Hospitals NHS Trust, London (United Kingdom). Inst. of Nuclear Medicine

    1996-12-31

    This protocol addresses the performance assessment of single and dual headed gamma cameras. No attempt is made to assess the performance of any associated computing systems. Evaluations are usually performed on a gamma camera commercially available within the United Kingdom and recently installed at a clinical site. In consultation with the manufacturer, GCAT selects the site and liaises with local staff to arrange a mutually convenient time for assessment. The manufacturer is encouraged to have a representative present during the evaluation. Three to four days are typically required for the evaluation team to perform the necessary measurements. When access time is limited, the team will modify the protocol to test the camera as thoroughly as possible. Data are acquired on the camera`s computer system and are subsequently transferred to the independent GCAT computer system for analysis. This transfer from site computer to the independent system is effected via a hardware interface and Interfile data transfer. (author).

  4. Heart imaging by cadmium telluride gamma camera European Program 'BIOMED' consortium

    CERN Document Server

    Scheiber, C; Chambron, J; Prat, V; Kazandjan, A; Jahnke, A; Matz, R; Thomas, S; Warren, S; Hage-Hali, M; Regal, R; Siffert, P; Karman, M

    1999-01-01

    Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3x3 mm, field of view: 15 cmx15 cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15 deg. tilt of the collimator with respect to the detector grid. A 16x16 CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16...

  5. Gamma camera calibration and validation for quantitative SPECT imaging with (177)Lu.

    Science.gov (United States)

    D'Arienzo, M; Cazzato, M; Cozzella, M L; Cox, M; D'Andrea, M; Fazio, A; Fenwick, A; Iaccarino, G; Johansson, L; Strigari, L; Ungania, S; De Felice, P

    2016-06-01

    Over the last years (177)Lu has received considerable attention from the clinical nuclear medicine community thanks to its wide range of applications in molecular radiotherapy, especially in peptide-receptor radionuclide therapy (PRRT). In addition to short-range beta particles, (177)Lu emits low energy gamma radiation of 113keV and 208keV that allows gamma camera quantitative imaging. Despite quantitative cancer imaging in molecular radiotherapy having been proven to be a key instrument for the assessment of therapeutic response, at present no general clinically accepted quantitative imaging protocol exists and absolute quantification studies are usually based on individual initiatives. The aim of this work was to develop and evaluate an approach to gamma camera calibration for absolute quantification in tomographic imaging with (177)Lu. We assessed the gamma camera calibration factors for a Philips IRIX and Philips AXIS gamma camera system using various reference geometries, both in air and in water. Images were corrected for the major effects that contribute to image degradation, i.e. attenuation, scatter and dead- time. We validated our method in non-reference geometry using an anthropomorphic torso phantom provided with the liver cavity uniformly filled with (177)LuCl3. Our results showed that calibration factors depend on the particular reference condition. In general, acquisitions performed with the IRIX gamma camera provided good results at 208keV, with agreement within 5% for all geometries. The use of a Jaszczak 16mL hollow sphere in water provided calibration factors capable of recovering the activity in anthropomorphic geometry within 1% for the 208keV peak, for both gamma cameras. The point source provided the poorest results, most likely because scatter and attenuation correction are not incorporated in the calibration factor. However, for both gamma cameras all geometries provided calibration factors capable of recovering the activity in

  6. Simulation of charge transport in pixelated CdTe

    OpenAIRE

    Kolstein, M.; G Ariño; Chmeissani, M.; De Lorenzo, G.

    2014-01-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated semiconductor technology for nuclear medicine applications to achieve an improved image reconstruction without efficiency loss. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). The design is based on the use of a pixelated CdTe Schottky detector to have op...

  7. Characterization of the count rate performance of modern gamma cameras

    Science.gov (United States)

    Silosky, M.; Johnson, V.; Beasley, C.; Cheenu Kappadath, S.

    2013-01-01

    Purpose: Evaluation of count rate performance (CRP) is an integral component of gamma camera quality assurance and system deadtime (τ) may be utilized for image correction in quantitative studies. This work characterizes the CRP of three modern gamma cameras and estimates τ using two established methods (decay and dual source) under a variety of experimental conditions. Methods: For the decay method, uncollimated detectors were exposed to a Tc-99m source of relatively high activity and count rates were sampled regularly over 48 h. Input count rate at each time point was based on the lowest observed count rate data point. The input count rate was plotted against the observed count rate and fit via least-squares to the paralyzable detector model (PDM) to estimate τ (rates method). A novel expression for observed counts as a function of measurement time interval was derived, taking into account the PDM and the presence of background but making no assumption regarding input count rate. The observed counts were fit via least-squares to this novel expression to estimate τ (counts method). Correlation and Bland-Altman analyses were performed to assess agreement in estimates of τ between the rates and counts methods. The dependence of τ on energy window definition and incident energy spectrum were characterized. The dual source method was also used to estimate τ and its agreement with estimates from the decay method under identical conditions was also investigated. The dependences of τ on the total activity and the ratio of source activities were characterized. Results: The observed CRP curves for each gamma camera agreed with the PDM at low count rates but deviated substantially from it at high count rates. The estimates of τ determined from the paralyzable portion of the CPR curve using the rates method and the counts method were found to be highly correlated (r = 0.999) but with a small (∼6%) difference. No statistically significant difference was observed

  8. Simulation of the functioning of a gamma camera using Monte Carlo method; Simulacion del funcionamiento de una camara gamma mediante metodo Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Oramas Polo, I.

    2014-07-01

    This paper presents the simulation of the gamma camera Park Isocam II by Monte Carlo code SIMIND. This simulation allows detailed assessment of the functioning of the gamma camera. The parameters evaluated by means of the simulation are: the intrinsic uniformity with different window amplitudes, the system uniformity, the extrinsic spatial resolution, the maximum rate of counts, the intrinsic sensitivity, the system sensitivity, the energy resolution and the pixel size. The results of the simulation are compared and evaluated against the specifications of the manufacturer of the gamma camera and taking into account the National Protocol for Quality Control of Nuclear Medicine Instruments of the Cuban Medical Equipment Control Center. The simulation reported here demonstrates the validity of the SIMIND Monte Carlo code to evaluate the performance of the gamma camera Park Isocam II and as result a computational model of the camera has been obtained. (Author)

  9. The use of a portable gamma camera for preoperative lymphatic mapping: a comparison with a conventional gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Vidal-Sicart, Sergi; Paredes, Pilar [Hospital Clinic Barcelona, Nuclear Medicine Department (CDIC), Barcelona (Spain); Institut d' Investigacio Biomedica Agusti Pi Sunyer (IDIBAPS), Barcelona (Spain); Vermeeren, Lenka; Valdes-Olmos, Renato A. [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital (NKI-AVL), Nuclear Medicine Department, Amsterdam (Netherlands); Sola, Oriol [Hospital Clinic Barcelona, Nuclear Medicine Department (CDIC), Barcelona (Spain)

    2011-04-15

    Planar lymphoscintigraphy is routinely used for preoperative sentinel node visualization, but large gamma cameras are not always available. We evaluated the reproducibility of lymphatic mapping with a smaller and portable gamma camera. In two centres, 52 patients with breast cancer received preoperative lymphoscintigraphy with a conventional gamma camera with a field of view of 40 x 40 cm. Static anterior and lateral images were performed at 15 min, 2 h and 4 h after injection of the radiotracer ({sup 99m}Tc-nanocolloid). At 2 h after injection, anterior and oblique images were also performed with a portable gamma camera (Sentinella, Oncovision) positioned to obtain a field of view of 20 x 20 cm. Visualization of lymphatic drainage on conventional images and images with the portable device were compared for number of nodes depicted, their intensity and localization of sentinel nodes. The images performed with the conventional gamma camera depicted sentinel nodes in 94%, while the portable gamma camera showed drainage in 73%. There was however no significant difference in visualization between the two devices when a lead shield was used to mask the injection area in 43 patients (95 vs 88%, p = 0.25). Second-echelon nodes were visualized in 62% of the patients with the conventional gamma camera and in 29% of the cases with the portable gamma camera. Preoperative imaging with a portable gamma camera fitted with a pinhole collimator to obtain a field of view of 20 x 20 cm is able to depict sentinel nodes in 88% of the cases, if a lead shield is used to mask the injection site. This device may be useful in centres without the possibility to perform a preoperative image. (orig.)

  10. Gamma camera based Positron Emission Tomography: a study of the viability on quantification; Tomografia por emissao de positrons com sistemas PET/SPECT: um estudo da viabilidade de quantifizacao

    Energy Technology Data Exchange (ETDEWEB)

    Pozzo, Lorena

    2005-07-01

    Positron Emission Tomography (PET) is a Nuclear Medicine imaging modality for diagnostic purposes. Pharmaceuticals labeled with positron emitters are used and images which represent the in vivo biochemical process within tissues can be obtained. The positron/electron annihilation photons are detected in coincidence and this information is used for object reconstruction. Presently, there are two types of systems available for this imaging modality: the dedicated systems and those based on gamma camera technology. In this work, we utilized PET/SPECT systems, which also allows for the traditional Nuclear Medicine studies based on single photon emitters. There are inherent difficulties which affect quantification of activity and other indices. They are related to the Poisson nature of radioactivity, to radiation interactions with patient body and detector, noise due to statistical nature of these interactions and to all the detection processes, as well as the patient acquisition protocols. Corrections are described in the literature and not all of them are implemented by the manufacturers: scatter, attenuation, random, decay, dead time, spatial resolution, and others related to the properties of each equipment. The goal of this work was to assess these methods adopted by two manufacturers, as well as the influence of some technical characteristics of PET/SPECT systems on the estimation of SUV. Data from a set of phantoms were collected in 3D mode by one camera and 2D, by the other. We concluded that quantification is viable in PET/SPECT systems, including the estimation of SUVs. This is only possible if, apart from the above mentioned corrections, the camera is well tuned and coefficients for sensitivity normalization and partial volume corrections are applied. We also verified that the shapes of the sources used for obtaining these factors play a role on the final results and should be delt with carefully in clinical quantification. Finally, the choice of the region

  11. First use of mini gamma cameras for intra-operative robotic SPECT reconstruction.

    Science.gov (United States)

    Matthies, Philipp; Sharma, Kanishka; Okur, Ash; Gardiazabal, José; Vogel, Jakob; Lasserl, Tobias; Navab, Nassir

    2013-01-01

    Different types of nuclear imaging systems have been used in the past, starting with pre-operative gantry-based SPECT systems and gamma cameras for 2D imaging of radioactive distributions. The main applications are concentrated on diagnostic imaging, since traditional SPECT systems and gamma cameras are bulky and heavy. With the development of compact gamma cameras with good resolution and high sensitivity, it is now possible to use them without a fixed imaging gantry. Mounting the camera onto a robot arm solves the weight issue, while also providing a highly repeatable and reliable acquisition platform. In this work we introduce a novel robotic setup performing scans with a mini gamma camera, along with the required calibration steps, and show the first SPECT reconstructions. The results are extremely promising, both in terms of image quality as well as reproducibility. In our experiments, the novel setup outperformed a commercial fhSPECT system, reaching accuracies comparable to state-of-the-art SPECT systems.

  12. Design and characterization of a low profile NaI(Tl) gamma camera for dedicated molecular breast tomosynthesis

    Science.gov (United States)

    Polemi, Andrew M.; Niestroy, Justin; Stolin, Alexander; Jaliparthi, Gangadhar; Wojcik, Randy; Majewski, Stan; Williams, Mark B.

    2016-10-01

    A new low profile gamma camera is being developed for use in a dual modality (x-ray transmission and gamma-ray emission) tomosynthesis system. Compared to the system's current gamma camera, the new camera has a larger field of view ( 20x25 cm) to better match the system's x-ray detector ( 23x29 cm), and is thinner (7.3 cm instead of 10.3 cm) permitting easier camera positioning near the top surface of the breast. It contains a pixelated NaI(Tl) array with a crystal pitch of 2.2 mm, which is optically coupled to a 4x5 array of Hamamatsu H8500C position sensitive photomultiplier tubes (PSPMTs). The manufacturer-provided connector board of each PSPMT was replaced with a custom designed board that a) reduces the 64 channel readout of the 8x8 electrode anode of the H8500C to 16 channels (8X and 8Y), b) performs gain non-uniformity correction, and c) reduces the height of the PSPMT-base assembly, 37.7 mm to 27.87 mm. The X and Y outputs of each module are connected in a lattice framework, and at two edges of this lattice, the X and Y outputs (32Y by 40X) are coupled to an amplifier/output board whose signals are fed via shielded ribbon cables to external ADCs. The camera uses parallel hole collimation. We describe the measured camera imaging performance, including intrinsic and extrinsic spatial resolution, detection sensitivity, uniformity of response, energy resolution for 140 keV gamma rays, and geometric linearity.

  13. Iterative reconstruction of detector response of an Anger gamma camera

    Science.gov (United States)

    Morozov, A.; Solovov, V.; Alves, F.; Domingos, V.; Martins, R.; Neves, F.; Chepel, V.

    2015-05-01

    Statistical event reconstruction techniques can give better results for gamma cameras than the traditional centroid method. However, implementation of such techniques requires detailed knowledge of the photomultiplier tube light-response functions. Here we describe an iterative method which allows one to obtain the response functions from flood irradiation data without imposing strict requirements on the spatial uniformity of the event distribution. A successful application of the method for medical gamma cameras is demonstrated using both simulated and experimental data. An implementation of the iterative reconstruction technique capable of operating in real time is presented. We show that this technique can also be used for monitoring photomultiplier gain variations.

  14. Maximum Likelihood Expectation-Maximization Algorithms Applied to Localization and Identification of Radioactive Sources with Recent Coded Mask Gamma Cameras

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, H.; Barat, E.; Carrel, F.; Dautremer, T.; Dubos, S.; Limousin, O.; Montagu, T.; Normand, S.; Schoepff, V. [CEA, Gif-sur-Yvette, F-91191 (France); Amgarou, K.; Menaa, N. [CANBERRA, 1, rue des Herons, Saint Quentin en Yvelines, F-78182 (France); Angelique, J.-C. [LPC, 6, boulevard du Marechal Juin, F-14050 (France); Patoz, A. [CANBERRA, 10, route de Vauzelles, Loches, F-37600 (France)

    2015-07-01

    In this work, we tested Maximum likelihood expectation-maximization (MLEM) algorithms optimized for gamma imaging applications on two recent coded mask gamma cameras. We respectively took advantage of the characteristics of the GAMPIX and Caliste HD-based gamma cameras: noise reduction thanks to mask/anti-mask procedure but limited energy resolution for GAMPIX, high energy resolution for Caliste HD. One of our short-term perspectives is the test of MAPEM algorithms integrating specific prior values for the data to reconstruct adapted to the gamma imaging topic. (authors)

  15. Determination of the detective quantum efficiency of gamma camera systems: a Monte Carlo study.

    Science.gov (United States)

    Eriksson, Ida; Starck, Sven-Ake; Båth, Magnus

    2010-01-01

    The purpose of the present work was to investigate the validity of using the Monte Carlo technique for determining the detective quantum efficiency (DQE) of a gamma camera system and to use this technique in investigating the DQE behaviour of a gamma camera system and its dependency on a number of relevant parameters. The Monte Carlo-based software SIMIND, simulating a complete gamma camera system, was used in the present study. The modulation transfer function (MTF) of the system was determined from simulated images of a point source of (99m)Tc, positioned at different depths in a water phantom. Simulations were performed using different collimators and energy windows. The MTF of the system was combined with the photon yield and the sensitivity, obtained from the simulations, to form the frequency-dependent DQE of the system. As figure-of-merit (FOM), the integral of the 2D DQE was used. The simulated DQE curves agreed well with published data. As expected, there was a strong dependency of the shape and magnitude of the DQE curve on the collimator, energy window and imaging position. The highest FOM was obtained for a lower energy threshold of 127 keV for objects close to the detector and 131 keV for objects deeper in the phantom, supporting an asymmetric window setting to reduce scatter. The Monte Carlo software SIMIND can be used to determine the DQE of a gamma camera system from a simulated point source alone. The optimal DQE results in the present study were obtained for parameter settings close to the clinically used settings.

  16. A compact gamma camera for biological imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, E L; Cella, J; Majewski, S; Popov, V; Qian, Jianguo; Saha, M S; Smith, M F; Weisenberger, A G; Welsh, R E

    2006-02-01

    A compact detector, sized particularly for imaging a mouse, is described. The active area of the detector is approximately 46 mm; spl times/ 96 mm. Two flat-panel Hamamatsu H8500 position-sensitive photomultiplier tubes (PSPMTs) are coupled to a pixellated NaI(Tl) scintillator which views the animal through a copper-beryllium (CuBe) parallel-hole collimator specially designed for {sup 125}I. Although the PSPMTs have insensitive areas at their edges and there is a physical gap, corrections for scintillation light collection at the junction between the two tubes results in a uniform response across the entire rectangular area of the detector. The system described has been developed to optimize both sensitivity and resolution for in-vivo imaging of small animals injected with iodinated compounds. We demonstrate an in-vivo application of this detector, particularly to SPECT, by imaging mice injected with approximately 10-15; spl mu/Ci of {sup 125}I.

  17. Implementation of test for quality assurance in nuclear medicine gamma camera

    Science.gov (United States)

    Moreno, A. Montoya; Laguna, A. Rodríguez; Zamudio, Flavio E. Trujillo

    2012-10-01

    In nuclear medicine (NM) over 90% of procedures are performed for diagnostic purposes. To ensure adequate diagnostic quality of images and the optimization of the doses received by patients originated from the radioactive material is essential for regular monitoring and equipment performance through a quality assurance program (QAP). The QAP consists of 15 proposed performance tomographic and not tomographic gamma camera (GC) tests, and is based on recommendations of international organizations. We describe some results of the performance parameters of QAP applied to a GC model e.cam Siemens, of the Department of NM of the National Cancer Institute of Mexico (INCan). The results were: (1) The average intrinsic spatial resolution (Rin) was 4.67 ± 0.25 mm at the limit of acceptance criterion of 4.4 mm. (2) The sensitivity extrinsic (Sext), with maximum variations of 1.8% (less than 2% which is the criterion of acceptance). (3) Rotational Uniformity (Urot), with values of integral uniformity (IU) in the useful field of view detector (UFOV), with maximum percentage change of 0.97% and monthly variations equal angles, ranging from 0.13 to 0.99% less than 1%. (4) The displacement of the center of rotation (DCOR), indicated a maximum deviation of 0.155 ± 0.039 mm less than 4.795 mm, an absolute deviation of less than 0.5 where pixel 0.085 pixel is suggested, the criteria are assigned to low-energy collimator high resolution. (5) In tomographic uniformity (Utomo), UI values (%) and percentage noise level (rms%) were 7.54 ± 1.53 and 4.18 ± 1.69 which are consistent with the limits of acceptance of 7.0-12.0% and 3.0-6.0% respectively. The smallest cold sphere has a diameter of 11.4 mm. The implementation of a QAP allows for high quality diagnostic images, optimization of the doses given to patients, a reduction of exposure to occupationally exposed workers (POE, by its Spanish acronym), and generally improves the productivity of the service. This proposal can be used to

  18. Implementation of test for quality assurance in nuclear medicine gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Montoya Moreno, A.; Rodriguez Laguna, A.; Trujillo Zamudio, Flavio E [Department of Nuclear Medicine, National Cancer Institute San Fernando Avenue No.22, Col. Section XVI (Mexico)

    2012-10-23

    In nuclear medicine (NM) over 90% of procedures are performed for diagnostic purposes. To ensure adequate diagnostic quality of images and the optimization of the doses received by patients originated from the radioactive material is essential for regular monitoring and equipment performance through a quality assurance program (QAP). The QAP consists of 15 proposed performance tomographic and not tomographic gamma camera (GC) tests, and is based on recommendations of international organizations. We describe some results of the performance parameters of QAP applied to a GC model e.cam Siemens, of the Department of NM of the National Cancer Institute of Mexico (INCan). The results were: (1) The average intrinsic spatial resolution (R{sub in}) was 4.67 {+-} 0.25 mm at the limit of acceptance criterion of 4.4 mm. (2) The sensitivity extrinsic (S{sub ext}), with maximum variations of 1.8% (less than 2% which is the criterion of acceptance). (3) Rotational Uniformity (U{sub rot}), with values of integral uniformity (IU) in the useful field of view detector (UFOV), with maximum percentage change of 0.97% and monthly variations equal angles, ranging from 0.13 to 0.99% less than 1%. (4) The displacement of the center of rotation (DCOR), indicated a maximum deviation of 0.155 {+-} 0.039 mm less than 4.795 mm, an absolute deviation of less than 0.5 where pixel 0.085 pixel is suggested, the criteria are assigned to low-energy collimator high resolution. (5) In tomographic uniformity (U{sub tomo}), UI values (%) and percentage noise level (rms%) were 7.54 {+-} 1.53 and 4.18 {+-} 1.69 which are consistent with the limits of acceptance of 7.0-12.0% and 3.0-6.0% respectively. The smallest cold sphere has a diameter of 11.4 mm. The implementation of a QAP allows for high quality diagnostic images, optimization of the doses given to patients, a reduction of exposure to occupationally exposed workers (POE, by its Spanish acronym), and generally improves the productivity of the

  19. Imaging of radiocesium uptake dynamics in a plant body using a newly developed high-resolution gamma camera for radiocesium

    Energy Technology Data Exchange (ETDEWEB)

    Kawachi, Naoki; Yin, Yong-Gen; Suzui, Nobuo; Ishii, Satomi; Fujimaki, Shu [Radiotracer Imaging Gr., Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Yoshihara, Toshihiro [Plant Molecular Biology, Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194 (Japan); Watabe, Hiroshi [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 (Japan); Yamamoto, Seiichi [Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya 461-8673 (Japan)

    2014-07-01

    Vast agricultural and forest areas around the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station in Japan were contaminated with radiocesium (Cs-134 and Cs-137) after the accident following the earthquake and tsunami in March 2011. A variety of agricultural studies, such as fertilizer management and plant breeding, have been undertaken intensively for reduction of radiocesium uptake in crops, or, enhancement of uptake in phyto-remediation. In this study, we newly developed a gamma camera specific for plant nutritional research, and performed quantitative analyses on uptake and partitioning of radiocesium in intact plant bodies. In general, gamma camera is a common technology in medical imaging, but it is not applicable to high-energy gamma rays such as emissions from Cs-137 (662 keV). Therefore, we designed our new gamma camera to prevent the penetration and scattering of the high-energy gamma rays. A single-crystal scintillator, Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG), was employed, which has a relatively high density, a large light output, no natural radioactivity and no hygroscopicity. A 44 x 44 matrix of the Ce:GAGG pixels, with dimensions of 0.85 mm x 0.85 mm x 10 mm for each pixel, was coupled to a high-quantum efficiency position sensitive photomultiplier tube. This gamma detector unit was encased in a 20-mm-thick tungsten container with a tungsten pinhole collimator on the front. By using this gamma camera, soybean plants (Glycine max), grown in hydroponic solutions and fed with 1-2 MBq of Cs-137, were imaged for 6.5 days in maximum to investigate and visualize the uptake dynamics into/within the areal part. As a result, radiocesium gradually appeared in the shoot several hours after feeding of Cs-137, and then accumulated intensively in the maturing pods and seeds in a characteristic pattern. Our results also demonstrated that this gamma-camera method enables quantitative evaluation of plant ability to absorb, transport

  20. Observed inter-camera variability of clinically relevant performance characteristics for Siemens Symbia gamma cameras.

    Science.gov (United States)

    Kappadath, S Cheenu; Erwin, William D; Wendt, Richard E

    2006-11-28

    We conducted an evaluation of the intercamera (i.e., between cameras) variability in clinically relevant performance characteristics for Symbia gamma cameras (Siemens Medical Solutions, Malvern, PA) based on measurements made using nine separate systems. The significance of the observed intercamera variability was determined by comparing it to the intracamera (i.e., within a single camera) variability. Measurements of performance characteristics were based on the standards of the National Electrical Manufacturers Association and reports 6, 9, 22, and 52 from the American Association of Physicists in Medicine. All measurements were performed using 99mTc (except 57Co used for extrinsic resolution) and low-energy, high-resolution collimation. Of the nine cameras, four have crystals 3/8 in. thick and five have crystals 5/8 in. thick. We evaluated intrinsic energy resolution, intrinsic and extrinsic spatial resolution, intrinsic integral and differential flood uniformity over the useful field-of-view, count rate at 20% count loss, planar sensitivity, single-photon emission computed tomography (SPECT) resolution, and SPECT integral uniformity. The intracamera variability was estimated by repeated measurements of the performance characteristics on a single system. The significance of the observed intercamera variability was evaluated using the two-tailed F distribution. The planar sensitivity of the gamma cameras tested was found be variable at the 99.8% confidence level for both the 3/8-in. and 5/8-in. crystal systems. The integral uniformity and energy resolution were found to be variable only for the 5/8-in. crystal systems at the 98% and 90% confidence level, respectively. All other performance characteristics tested exhibited no significant variability between camera systems. The measured variability reported here could perhaps be used to define nominal performance values of Symbia gamma cameras for planar and SPECT imaging.

  1. A 3D high-resolution gamma camera for radiopharmaceutical studies with small animals

    CERN Document Server

    Loudos, G K; Giokaris, N D; Styliaris, E; Archimandritis, S C; Varvarigou, A D; Papanicolas, C N; Majewski, S; Weisenberger, D; Pani, R; Scopinaro, F; Uzunoglu, N K; Maintas, D; Stefanis, K

    2003-01-01

    The results of studies conducted with a small field of view tomographic gamma camera based on a Position Sensitive Photomultiplier Tube are reported. The system has been used for the evaluation of radiopharmaceuticals in small animals. Phantom studies have shown a spatial resolution of 2 mm in planar and 2-3 mm in tomographic imaging. Imaging studies in mice have been carried out both in 2D and 3D. Conventional radiopharmaceuticals have been used and the results have been compared with images from a clinically used system.

  2. Mini gamma camera, camera system and method of use

    Science.gov (United States)

    Majewski, Stanislaw; Weisenberger, Andrew G.; Wojcik, Randolph F.

    2001-01-01

    A gamma camera comprising essentially and in order from the front outer or gamma ray impinging surface: 1) a collimator, 2) a scintillator layer, 3) a light guide, 4) an array of position sensitive, high resolution photomultiplier tubes, and 5) printed circuitry for receipt of the output of the photomultipliers. There is also described, a system wherein the output supplied by the high resolution, position sensitive photomultipiler tubes is communicated to: a) a digitizer and b) a computer where it is processed using advanced image processing techniques and a specific algorithm to calculate the center of gravity of any abnormality observed during imaging, and c) optional image display and telecommunications ports.

  3. Adaptive bad pixel correction algorithm for IRFPA based on PCNN

    Science.gov (United States)

    Leng, Hanbing; Zhou, Zuofeng; Cao, Jianzhong; Yi, Bo; Yan, Aqi; Zhang, Jian

    2013-10-01

    Bad pixels and response non-uniformity are the primary obstacles when IRFPA is used in different thermal imaging systems. The bad pixels of IRFPA include fixed bad pixels and random bad pixels. The former is caused by material or manufacture defect and their positions are always fixed, the latter is caused by temperature drift and their positions are always changing. Traditional radiometric calibration-based bad pixel detection and compensation algorithm is only valid to the fixed bad pixels. Scene-based bad pixel correction algorithm is the effective way to eliminate these two kinds of bad pixels. Currently, the most used scene-based bad pixel correction algorithm is based on adaptive median filter (AMF). In this algorithm, bad pixels are regarded as image noise and then be replaced by filtered value. However, missed correction and false correction often happens when AMF is used to handle complex infrared scenes. To solve this problem, a new adaptive bad pixel correction algorithm based on pulse coupled neural networks (PCNN) is proposed. Potential bad pixels are detected by PCNN in the first step, then image sequences are used periodically to confirm the real bad pixels and exclude the false one, finally bad pixels are replaced by the filtered result. With the real infrared images obtained from a camera, the experiment results show the effectiveness of the proposed algorithm.

  4. Region based elimination of noise pixels towards optimized classifier models for skin pixel detection

    Directory of Open Access Journals (Sweden)

    Gagandeep Kaur

    2015-03-01

    Full Text Available The extraction of the skin pixels in a human image and rejection of non-skin pixels is called the skin segmentation. Skin pixel detection is the process of extracting the skin pixels in a human image which is typically used as a pre-processing step to extract the face regions from human image. In past, there are several computer vision approaches and techniques have been developed for skin pixel detection. In the process of skin detection, given pixels are been transformed into an appropriate color space such as RGB, HSV etc. And then skin classifier model have been applied to label the pixel into skin or non-skin regions. Here in this research a “Region based elimination of noise pixels and performance analysis of classifier models for skin pixel detection applied on human images” would be performed which involve the process of image representation in color models, elimination of non-skin pixels in the image, and then pre-processing and cleansing of the collected data, feature selection of the human image and then building the model for classifier. In this research and implementation of skin pixels classifier models are proposed with their comparative performance analysis. The definition of the feature vector is simply the selection of skin pixels from the human image or stack of human images. The performance is evaluated by comparing and analysing skin colour segmentation algorithms. During the course of research implementation, efforts are iterative which help in selection of optimized skin classifier based on the machine learning algorithms and their performance analysis.

  5. SiPM arrays and miniaturized readout electronics for compact gamma camera

    Science.gov (United States)

    Dinu, N.; Imando, T. Ait; Nagai, A.; Pinot, L.; Puill, V.; Callier, S.; Janvier, B.; Esnault, C.; Verdier, M.-A.; Raux, L.; Vandenbussche, V.; Charon, Y.; Menard, L.

    2015-07-01

    This article reports on the design and features of a very compact and light gamma camera based on SiPM arrays and miniaturized readout electronics dedicated to tumor localization during radio-guided cancer surgery. This gamma camera, called MAGICS, is composed of four (2×2) photo-detection elementary modules coupled to an inorganic scintillator. The 256 channels photo-detection system covers a sensitive area of 54×53 m2. Each elementary module is based on four (2×2) SiPM monolithic arrays, each array consisting of 16 SiPM photo-sensors (4×4) with 3×3 mm2 sensitive area, coupled to a miniaturized readout electronics and a dedicated ASIC. The overall dimensions of the electronics fit the size of the detector, enabling to assemble side-by-side several elementary modules in a close-packed arrangement. The preliminary performances of the system are very encouraging, showing an energy resolution of 9.8% and a spatial resolution of less than 1 mm at 122 keV.

  6. SiPM arrays and miniaturized readout electronics for compact gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Dinu, N., E-mail: dinu@lal.in2p3.fr [Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay (France); Imando, T. Ait; Nagai, A. [Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay (France); Pinot, L. [Laboratory of Imaging and Modelisation in Neurobiology and Cancerology, IN2P3, CNRS, Orsay (France); Puill, V. [Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay (France); Callier, S. [Omega Microelectronics Group, CNRS, Palaiseau (France); Janvier, B.; Esnault, C.; Verdier, M.-A. [Laboratory of Imaging and Modelisation in Neurobiology and Cancerology, IN2P3, CNRS, Orsay (France); Raux, L. [Omega Microelectronics Group, CNRS, Palaiseau (France); Vandenbussche, V.; Charon, Y.; Menard, L. [Laboratory of Imaging and Modelisation in Neurobiology and Cancerology, IN2P3, CNRS, Orsay (France)

    2015-07-01

    This article reports on the design and features of a very compact and light gamma camera based on SiPM arrays and miniaturized readout electronics dedicated to tumor localization during radio-guided cancer surgery. This gamma camera, called MAGICS, is composed of four (2×2) photo-detection elementary modules coupled to an inorganic scintillator. The 256 channels photo-detection system covers a sensitive area of 54×53 m{sup 2}. Each elementary module is based on four (2×2) SiPM monolithic arrays, each array consisting of 16 SiPM photo-sensors (4×4) with 3×3 mm{sup 2} sensitive area, coupled to a miniaturized readout electronics and a dedicated ASIC. The overall dimensions of the electronics fit the size of the detector, enabling to assemble side-by-side several elementary modules in a close-packed arrangement. The preliminary performances of the system are very encouraging, showing an energy resolution of 9.8% and a spatial resolution of less than 1 mm at 122 keV.

  7. Eliminating spatial distortions in Anger-type gamma cameras

    Science.gov (United States)

    Leitner, Michael; Ceeh, Hubert; Weber, Josef-Andreas

    2012-12-01

    A procedure to quantify and correct the spatial distortions inherent to Anger-type gamma cameras is presented. It consists in imaging a pattern of regularly spaced holes, assigning to each pair of lattice indices the actual position on the detector and generating a look-up matrix describing the inverse mapping. This allows one to correct the position of the distinct events either during or after the measurement with minimal computational effort. The corrected spectrum is indistinguishable from a spectrum taken with an ideal detector in a statistical sense. The effect of the increased resolution on measurements of angular correlation of positron annihilation radiation is demonstrated. The presented scheme is applicable for all types of area detectors.

  8. Monte-Carlo simulation of pinhole collimator of a small field of view gamma camera for small animal imaging

    Institute of Scientific and Technical Information of China (English)

    ZHU Jie; MA Wenyan; ZHU Yufeng; MA Hongguang; WU Yuelei; HU Huasi; ZHANG Boping; HUO Yonggang; LIU Silu; JIAN Bin; WANG Zhaomin

    2009-01-01

    Needs in scintimammography applications,especially for small animal cardiac imaging,lead to develop a small field of view,high spatial resolution gamma camera with a pinhole collimator.However the ideal pinhole collimator must keep a compromise between spatial resolution and sensitivity.In order to design a pinhole collimator with an optimized sensitivity and spatial resolution,the spatial resolution and the geometric sensitivity response as a function of the source to collimator distance has been obtained by means of Monte-Carlo simulation for a small field of view gamma camera with a pinhole collimator of various-hole diameters.The results show that the camera with pinhole of 1 mm,1.5 mm and 2 mm diameter has respectively spatial resolution of 1.5 mm,2.25 mm and 3 mm and geometric sensitivity of 0.016%,0.022% and 0.036%,while the source to collimator distance is 3 cm.We chose the pinhole collimator with hole diameter size of 1.2 mm for our the gamma camera designed based on the wade-off between sensitivity and resolution.

  9. Analytical and experimental FWHM of a gamma camera: theoretical and practical issues

    Directory of Open Access Journals (Sweden)

    Diego Cecchin

    2015-02-01

    Full Text Available Introduction. It is well known that resolution on a gamma camera varies as a function of distance, scatter and the camera’s characteristics (collimator type, crystal thickness, intrinsic resolution etc. Manufacturers frequently provide only a few pre-calculated resolution values (using a line source in air, 10–15 cm from the collimator surface and without scattering. However, these are typically not obtained in situations resembling a clinical setting. From a diagnostic point of view, it is useful to know the expected resolution of a gamma camera at a given distance from the collimator surface for a particular setting in order to decide whether it is worth scanning patients with “small lesion” or not. When dealing with absolute quantification it is also mandatory to know precisely the expected resolution and its uncertainty in order to make appropriate corrections.Aim. Our aims are: to test a novel mathematical approach, the cubic spline interpolation, for the extraction of the full width at half maximum (FWHM from the acquisition of a line source (experimental resolution also considering measurement uncertainty; to compare it with the usually adopted methods such as the gaussian approach; to compare it with the theoretical resolution (analytical resolution of a gamma camera at different distances; to create a web-based educational program with which to test these theories.Methods. Three mathematical methods (direct calculation, global interpolation using gaussian and local interpolation using splines for calculating FWHM from a line source (planar scintigraphy were tested and compared. A NEMA Triple Line Source Phantom was used to obtain static images both in air and with different scattering levels. An advanced, open-source software (MATLAB/Octave and PHP based was created “ad hoc” to obtain and compare FWHM values and relative uncertainty.Results and Conclusion. Local interpolation using splines proved faster and more reliable

  10. FDG gamma camera PET equipped with one inch crystal and XCT. Assessment of myocardial viability

    Energy Technology Data Exchange (ETDEWEB)

    Beheshti, M. [Dept. of Nuclear Medicine, Medical Univ., General Hospital of Vienna (Austria); Dept. of Nuclear Medicine and Endocrinology, PET CT Centre, St. Vincent' s Hospital, Linz (Austria); Khorsand, A.; Graf, S. [Dept. of Cardiology, Medical Univ., General Hospital of Vienna (Austria); Dobrozemsky, G. [Dept. of Nuclear Medicine, Medical Univ. of Innsbruck (Austria); Oezer, S.; Kletter, K.; Dudczak, R. [Dept. of Nuclear Medicine, Medical Univ., General Hospital of Vienna (Austria); Pirich, C. [Dept. of Nuclear Medicine und Endocrinology, Paracelsus Private Medical Univ., SALK, Salzburg (Austria)

    2006-07-01

    Metabolic imaging with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) is actually considered as the best method to detect and quantitatively assess myocordial tissue viability. The aim of this study was to investigate the accuracy of FDG gamma camera positron emission tomography (GCPET) imaging equipped with one inch NaI crystals in comparison to FDG dedicated PET (dPET) imaging as a ''gold standard'' in phantom and clinical studies. Patients, methods: nineteen patients with coronary artery disease (CAD) underwent both imaging modalities. Phantom and clinical GCPET imaging were performed with a dual-headed, coincidence based gamma camera equipped with 1 inch thick NaI crystals and an X-ray tube (XCT) for attenuation correction (AC), as well as with a dedicated PET scanner with AC. {sup 99m}Tc tetrofosmin single-photon emission tomography (SPET) studies were performed for assessment of myocardial perfusion, with AC. Results: phantom studies showed a significant relation in segmental activity between FDG imaging with AC using GCPET and dPET (r = 0.91, p < 0.001). In clinical studies with AC correlation coefficients of mean segmental FDG uptake and regional defect size were r = 0.87 (p < 0.0001) and r = 0.83 (p < 0.0001), respectively. In regional analysis close agreement was even found in the most attenuated regions of the heart if AC was used in GCPET imaging. The overall agreement for detection of viable myocardium was 81% between FDG-dPET (AC) and FDG-GCPET (AC) and 74% between FDG-dPET (AC) and FDG-GCPET (NC). Conclusions: suggests that the assessment of myocardial metabolism by means of FDG is feasible with a coincidence based gamma camera equipped with 1 inch thick NaI crystal if AC is performed. The results reveal a close concordance and agreement between FDG-dPET (AC) and FDG-GCPET (AC) as compared to FDG-GCPET (NC). (orig.)

  11. PIXELS: Using field-based learning to investigate students' concepts of pixels and sense of scale

    Science.gov (United States)

    Pope, A.; Tinigin, L.; Petcovic, H. L.; Ormand, C. J.; LaDue, N.

    2015-12-01

    Empirical work over the past decade supports the notion that a high level of spatial thinking skill is critical to success in the geosciences. Spatial thinking incorporates a host of sub-skills such as mentally rotating an object, imagining the inside of a 3D object based on outside patterns, unfolding a landscape, and disembedding critical patterns from background noise. In this study, we focus on sense of scale, which refers to how an individual quantified space, and is thought to develop through kinesthetic experiences. Remote sensing data are increasingly being used for wide-reaching and high impact research. A sense of scale is critical to many areas of the geosciences, including understanding and interpreting remotely sensed imagery. In this exploratory study, students (N=17) attending the Juneau Icefield Research Program participated in a 3-hour exercise designed to study how a field-based activity might impact their sense of scale and their conceptions of pixels in remotely sensed imagery. Prior to the activity, students had an introductory remote sensing lecture and completed the Sense of Scale inventory. Students walked and/or skied the perimeter of several pixel types, including a 1 m square (representing a WorldView sensor's pixel), a 30 m square (a Landsat pixel) and a 500 m square (a MODIS pixel). The group took reflectance measurements using a field radiometer as they physically traced out the pixel. The exercise was repeated in two different areas, one with homogenous reflectance, and another with heterogeneous reflectance. After the exercise, students again completed the Sense of Scale instrument and a demographic survey. This presentation will share the effects and efficacy of the field-based intervention to teach remote sensing concepts and to investigate potential relationships between students' concepts of pixels and sense of scale.

  12. A PFM based digital pixel with off-pixel residue measurement for 15μm pitch MWIR FPAs

    Science.gov (United States)

    Abbasi, Shahbaz; Shafique, Atia; Galioglu, Arman; Ceylan, Omer; Yazici, Melik; Gurbuz, Yasar

    2016-05-01

    Digital pixels based on pulse frequency modulation (PFM) employ counting techniques to achieve very high charge handling capability compared to their analog counterparts. Moreover, extended counting methods making use of leftover charge (residue) on the integration capacitor help improve the noise performance of these pixels. However, medium wave infrared (MWIR) focal plane arrays (FPAs) having smaller pixel pitch are constrained in terms of pixel area which makes it difficult to add extended counting circuitry to the pixel. Thus, this paper investigates the performance of digital pixels employing off-pixel residue measurement. A circuit prototype of such a pixel has been designed for 15μm pixel pitch and fabricated in 90nm CMOS. The prototype is composed of a pixel front-end based on a PFM loop. The frontend is a modified version of conventional design providing a means for buffering the signal that needs to be converted to a digital value by an off-pixel ADC. The pixel has an integration phase and a residue measurement phase. Measured integration performance of the pixel has been reported in this paper for various detector currents and integration times.

  13. Pre-clinical and Clinical Evaluation of High Resolution, Mobile Gamma Camera and Positron Imaging Devices

    Science.gov (United States)

    2010-10-01

    S. Majewski, R. Wojcik, A.G. Weisenberger, B. Kross, V. Popov, “Correction for the Effects of Accidental Coincidences , Compton Scatter and Object... Coincidence Imaging with a Gamma Camera ”, IEEE Transactions on Nuclear Science, Vol. 48, No. 1, Feb. 2001, Pg. 98-105. [14] R.S. Miyaoka, S.K...Coleman, “Attenuation Effects in Gamma Camera Coincidence Imaging”, IEEE Transactions on Nuclear Science, Vol. 45, No. 6, Dec. 1998, Pg. 3115-3121

  14. The utility of intraoperative handheld gamma camera for detection of sentinel lymph nodes in melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Ozkan, Elgin; Eroglu, Aydan [Ankara University Medical School, Ankara (Turkmenistan)

    2015-12-15

    Accurate identification of the sentinel lymph node (SLN) is an important prognostic factor for melanoma. In a minority of cases drainage to interval nodal basins, such as the epitrochlear region, are possible. Intraoperative handheld gamma cameras have been used to detect SLNs which are located in different anatomical localizations. In this case we report the utility of an intraoperative handheld gamma camera in the localization of epitrochlear drainage of distal upper extremity melanoma and its impact on surgical procedure.

  15. Characterisation of a high resolution small field of view portable gamma camera.

    Science.gov (United States)

    Bugby, S L; Lees, J E; Bhatia, B S; Perkins, A C

    2014-05-01

    A handheld, high-resolution small field of view (SFOV) pinhole gamma camera has been characterised using a new set of protocols adapted from standards previously developed for large field of view (LFOV) systems. Parameters investigated include intrinsic and extrinsic spatial resolution, spatial linearity, uniformity, sensitivity, count rate capability and energy resolution. Camera characteristics are compared to some clinical LFOV gamma cameras and also to other SFOV cameras in development.

  16. Research on ionospheric tomography based on variable pixel height

    Science.gov (United States)

    Zheng, Dunyong; Li, Peiqing; He, Jie; Hu, Wusheng; Li, Chaokui

    2016-05-01

    A novel ionospheric tomography technique based on variable pixel height was developed for the tomographic reconstruction of the ionospheric electron density distribution. The method considers the height of each pixel as an unknown variable, which is retrieved during the inversion process together with the electron density values. In contrast to conventional computerized ionospheric tomography (CIT), which parameterizes the model with a fixed pixel height, the variable-pixel-height computerized ionospheric tomography (VHCIT) model applies a disturbance to the height of each pixel. In comparison with conventional CIT models, the VHCIT technique achieved superior results in a numerical simulation. A careful validation of the reliability and superiority of VHCIT was performed. According to the results of the statistical analysis of the average root mean square errors, the proposed model offers an improvement by 15% compared with conventional CIT models.

  17. Neural network based cluster creation in the ATLAS Pixel Detector

    CERN Document Server

    Andreazza, A; The ATLAS collaboration

    2012-01-01

    The read-out from individual pixels on planar semi-conductor sensors are grouped into clusters to reconstruct the location where a charged particle passed through the sensor. The resolution given by individual pixel sizes is significantly improved by using the information from the charge sharing be- tween pixels. Such analog cluster creation techniques have been used by the ATLAS experiment for many years to obtain an excellent performance. How- ever, in dense environments, such as those inside high-energy jets, clusters have an increased probability of merging the charge deposited by multiple particles. Recently, a neural network based algorithm which estimates both the cluster position and whether a cluster should be split has been developed for the ATLAS Pixel Detector. The algorithm significantly reduces ambigui- ties in the assignment of pixel detector measurement to tracks and improves the position accuracy with respect to standard techniques by taking into account the 2-dimensional charge distribution.

  18. Sub-pixel mapping method based on BP neural network

    Institute of Scientific and Technical Information of China (English)

    LI Jiao; WANG Li-guo; ZHANG Ye; GU Yan-feng

    2009-01-01

    A new sub-pixel mapping method based on BP neural network is proposed in order to determine the spatial distribution of class components in each mixed pixel. The network was used to train a model that describes the relationship between spatial distribution of target components in mixed pixel and its neighboring information. Then the sub-pixel scaled target could be predicted by the trained model. In order to improve the performance of BP network, BP learning algorithm with momentum was employed. The experiments were conducted both on synthetic images and on hyperspectral imagery (HSI). The results prove that this method is capable of estimating land covers fairly accurately and has a great superiority over some other sub-pixel mapping methods in terms of computational complexity.

  19. 131I activity quantification of gamma camera planar images

    Science.gov (United States)

    Barquero, Raquel; Garcia, Hugo P.; Incio, Monica G.; Minguez, Pablo; Cardenas, Alexander; Martínez, Daniel; Lassmann, Michael

    2017-02-01

    A procedure to estimate the activity in target tissues in patients during the therapeutic administration of 131I radiopharmaceutical treatment for thyroid conditions (hyperthyroidism and differentiated thyroid cancer) using a gamma camera (GC) with a high energy (HE) collimator, is proposed. Planar images are acquired for lesions of different sizes r, and at different distances d, in two HE GC systems. Defining a region of interest (ROI) on the image of size r, total counts n g are measured. Sensitivity S (cps MBq-1) in each acquisition is estimated as the product of the geometric G and the intrinsic efficiency η 0. The mean fluence of 364 keV photons arriving at the ROI per disintegration G, is calculated with the MCNPX code, simulating the entire GC and the HE collimator. Intrinsic efficiency η 0 is estimated from a calibration measurement of a plane reference source of 131I in air. Values of G and S for two GC systems—Philips Skylight and Siemens e-cam—are calculated. The total range of possible sensitivity values in thyroidal imaging in the e-cam and skylight GC measure from 7 cps MBq-1 to 35 cps MBq-1, and from 6 cps MBq-1 to 29 cps MBq-1, respectively. These sensitivity values have been verified with the SIMIND code, with good agreement between them. The results have been validated with experimental measurements in air, and in a medium with scatter and attenuation. The counts in the ROI can be produced by direct, scatter and penetration photons. The fluence value for direct photons is constant for any r and d values, but scatter and penetration photons show different values related to specific r and d values, resulting in the large sensitivity differences found. The sensitivity in thyroidal GC planar imaging is strongly dependent on uptake size, and distance from the GC. An individual value for the acquisition sensitivity of each lesion can significantly alleviate the level of uncertainty in the measurement of thyroid uptake activity for each patient.

  20. A study on the performance evaluation of small gamma camera collimators using detective quantun efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Ho Sang

    2008-02-15

    The anger-type gamma camera and novel marker compound using Tc-99m were firstly introduced in 1963. The gamma camera systems have being improved and applied to various fields, for example, medical, industrial, and environmental fields. Gamma camera is mainly composed of collimator, detector, and signal processor. And the radiative source is namely the imaging object. The collimator is essential component of gamma camera system because the imaging performance of system is mainly dependent on the collimator. The performance evaluation of collimators can be done by using evaluating factors. In this study, the novel factors for gamma camera evaluation are suggested. The established evaluating factors by NEMA are FWHM, sensitivity, and uniformity. They have some limitations in spite of their usefulness. Firstly, performance evaluation by those factors give insensitive and indirect results only. Secondly, the evaluation of noise property is ambiguous. Thirdly, there is no synthetic evaluation of system performance. Simulation with Monte Carlo code and experiment with a small camera camera were simultaenuously performed to verify novel evaluating factors. For the evaluation of spatial resolution, MTF was applied instead of FWHM. The MTF values presents excellent linear relationship with FWHM values. The NNPS was applied instead of uniformity and sensitivity for the evaluation of noise fluctuation. The NNPS values also presents linear relationship with sensitivity and unifomity. Moreover, these novel factors give quantities as the function of spatial frequencies. Finally, the DQE values were given by calculations with MTF, NNPS, and input SNR. DQE effectively presents the synthetic evaluation of gamma camera performance. It is the conclusion that MTF, NNPS, and DQE can be novel evaluating factors for gamma camera systems and the new factor for synthetic evaluation is derived.

  1. Modeling of a slanted-hole collimator in a compact endo-cavity gamma camera.

    Science.gov (United States)

    Kamuda, Mark; Cui, Yonggang; Lall, Terry; Ionson, Jim; Camarda, Giuseppe S.; Hossain, Anwar; Yang, Ge; Roy, Utpal N.; James, Ralph B.

    2013-09-01

    Having the ability to take an accurate 3D image of a tumor greatly helps doctors diagnose it and then create a treatment plan for a patient. One way to accomplish molecular imaging is to inject a radioactive tracer into a patient and then measure the gamma rays emitted from regions with high-uptake of the tracer, viz., the cancerous tissues. In large, expensive PET- or SPECT-imaging systems, the 3D imaging easily is accomplished by rotating the gamma-ray detectors and then employing software to reconstruct the 3D images from the multiple 2D projections at different angles of view. However, this method is impractical in a very compact imaging system due to anatomical considerations, e.g., the transrectal gamma camera under development at Brookhaven National Laboratory (BNL) for detection of intra-prostatic tumors. The camera uses pixilated cadmium zinc telluride (CdZnTe or CZT) detectors with matched parallel-hole collimator. Our research investigated the possibility of using a collimator with slanted holes to create 3D pictures of a radioactive source. The underlying concept is to take 2D projection images at different angles of view by adjusting the slant angle of the collimator, then using the 2D projection images to reconstruct the 3D image. To do this, we first simulated the response of a pixilated CZT detector to radiation sources placed in the field of view of the camera. Then, we formulated an algorithm to use the simulation results as prior knowledge and estimate the distribution of a shaped source from its 2D projection images. From the results of the simulation, we measured the spatial resolution of the camera as ~7-mm at a depth of 13.85-mm when using a detector with 2.46-mm pixel pitch and a collimator with 60° slant angle.

  2. Triple-head gamma camera PET: system overview and performance characteristics.

    Science.gov (United States)

    Grosev, D; Loncarić, S; Vandenberghe, S; Dodig, D

    2002-08-01

    Positron emission tomography (PET) is currently performed using either a dedicated PET scanner or scintillation gamma camera equipped with electronic circuitry for coincidence detection of 511 keV annihilation quanta (gamma camera PET system). Although the resolution limits of these two instruments are comparable, the sensitivity and count rate performance of the gamma camera PET system are several times lower than that of the PET scanner. Most gamma camera PET systems are manufactured as dual-detector systems capable of performing dual-head coincidence imaging. One possible step towards the improvement of the sensitivity of the gamma camera PET system is to add another detector head. This work investigates the characteristics of one such triple-head gamma camera PET system capable of performing triple-head coincidence imaging. The following performance characteristics of the system were assessed: spatial resolution, sensitivity, count rate performance. The spatial resolution, expressed as the full width at half-maximum (FWHM), at 1 cm radius is 5.9 mm; at 10 cm radius, the transverse radial resolution is 5.3 mm, whilst the transverse tangential and axial resolutions are 8.9 mm and 13.3 mm, respectively. The sensitivity for a standard cylindrical phantom is 255 counts.s(-1).MBq*(-1)), using a 30% width photopeak energy window. An increase of 35% in the PET sensitivity is achievable by opening an additional 30% width energy window in the Compton region. The count rate in coincidence mode, at the upper limit of the systems optimal performance, is 45 kc.s(-1) (kc=kilocounts) using the photopeak energy window only, and increases to 60 kc.s(-1) using the photopeak + Compton windows. Sensitivity results are compared with published data for a similar dual-head detector system.

  3. Implementation of TDI based digital pixel ROIC with 15μm pixel pitch

    Science.gov (United States)

    Ceylan, Omer; Shafique, Atia; Burak, A.; Caliskan, Can; Abbasi, Shahbaz; Yazici, Melik; Gurbuz, Yasar

    2016-05-01

    A 15um pixel pitch digital pixel for LWIR time delay integration (TDI) applications is implemented which occupies one fourth of pixel area compared to previous digital TDI implementation. TDI is implemented on 8 pixels with oversampling rate of 2. ROIC provides 16 bits output with 8 bits of MSB and 8 bits of LSB. Pixel can store 75 M electrons with a quantization noise of 500 electrons. Digital pixel TDI implementation is advantageous over analog counterparts considering power consumption, chip area and signal-to-noise ratio. Digital pixel TDI ROIC is fabricated with 0.18um CMOS process. In digital pixel TDI implementation photocurrent is integrated on a capacitor in pixel and converted to digital data in pixel. This digital data triggers the summation counters which implements TDI addition. After all pixels in a row contribute, the summed data is divided to the number of TDI pixels(N) to have the actual output which is square root of N improved version of a single pixel output in terms of signal-to-noise-ratio (SNR).

  4. Use of dual-head gamma camera in radionuclide internal contamination monitoring on radiation workers from a nuclear medicine department

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Laguna, A.; Brandan, M.E., E-mail: alejandro.rodriguez.laguna@gmail.com [Universidad Nacional Autonoma de Mexico, Mexico D.F. (Mexico). Instituto de Fisica; Trujillo-Zamudio, F.E.; Estrada-Lobato, E. [Instituto Nacional de Cancerologia, Mexico D.F. (Mexico)

    2008-07-01

    As a part of an internal dosimetry program that is performed at the Mexican National Institute of Cancerology - Nuclear Medicine Department, in the present work we suggest a procedure for the routinely monitoring of internal contamination on radiation workers and nuclear medicine staff. The procedure is based on the identification and quantification of contaminating radionuclides in human body by using a dual-head whole-body gamma camera. The results have shown that the procedures described in this study can be used to implement a method to quantify minimal accumulated activity in the main human organs to evaluate internal contamination with radionuclides. The high sensitivity of the uncollimated gamma camera is advantageous for the routinely detection and identification of small activities of internal contamination. But, the null spatial resolution makes impossible the definition of contaminated region of interest. Then, the use of collimators is necessary to the quantification of incorporated radionuclides activities in the main human organs and for the internal doses assessment. (author)

  5. An improved bit shuffling pixels-based image scrambling method

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hong; WANG Hong-xia; WANG Jin

    2011-01-01

    @@ Compared with the Arnold transform, the image scrambling method based on bit shuffling pixels is much more secure, and has higher efficiency and speed.However, the key space of this bit shuffling pixels based method is too small to resist exhaustive search attack.Therefore, an improved method based on chaos is proposed in this paper.The security of the improved scheme is enhanced by increasing the number of the keys.Theoretical analysis and experimental results show that the proposed method is effective and has higher security.

  6. Evaluation of the scattered radiation components produced in a gamma camera using Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Polo, Ivon Oramas, E-mail: ivonoramas67@gmail.com [Department of Nuclear Engineering, Faculty of Nuclear Sciences and Technologies, Higher Institute of Applied Science and Technology (InSTEC), La Habana (Cuba)

    2014-07-01

    Introduction: this paper presents a simulation for evaluation of the scattered radiation components produced in a gamma camera PARK using Monte Carlo code SIMIND. It simulates a whole body study with MDP (Methylene Diphosphonate) radiopharmaceutical based on Zubal anthropomorphic phantom, with some spinal lesions. Methods: the simulation was done by comparing 3 configurations for the detected photons. The corresponding energy spectra were obtained using Low Energy High Resolution collimator. The parameters related with the interactions and the fraction of events in the energy window, the simulated events of the spectrum and scatter events were calculated. Results: the simulation confirmed that the images without influence of scattering events have a higher number of valid recorded events and it improved the statistical quality of them. A comparison among different collimators was made. The parameters and detector energy spectrum were calculated for each simulation configuration with these collimators using {sup 99m}Tc. Conclusion: the simulation corroborated that LEHS collimator has higher sensitivity and HEHR collimator has lower sensitivity when they are used with low energy photons. (author)

  7. Level-1 pixel based tracking trigger algorithm for LHC upgrade

    Science.gov (United States)

    Moon, C.-S.; Savoy-Navarro, A.

    2015-10-01

    The Pixel Detector is the innermost detector of the tracking system of the Compact Muon Solenoid (CMS) experiment at CERN Large Hadron Collider (LHC) . It precisely determines the interaction point (primary vertex) of the events and the possible secondary vertexes due to heavy flavours (b and c quarks); it is part of the overall tracking system that allows reconstructing the tracks of the charged particles in the events and combined with the magnetic field to measure their momentum. The pixel detector allows measuring the tracks in the region closest to the interaction point. The Level-1 (real-time) pixel based tracking trigger is a novel trigger system that is currently being studied for the LHC upgrade. An important goal is developing real-time track reconstruction algorithms able to cope with very high rates and high flux of data in a very harsh environment. The pixel detector has an especially crucial role in precisely identifying the primary vertex of the rare physics events from the large pile-up (PU) of events. The goal of adding the pixel information already at the real-time level of the selection is to help reducing the total level-1 trigger rate while keeping an high selection capability. This is quite an innovative and challenging objective for the experiments upgrade for the High Luminosity LHC (HL-LHC) . The special case here addressed is the CMS experiment. This document describes exercises focusing on the development of a fast pixel track reconstruction where the pixel track matches with a Level-1 electron object using a ROOT-based simulation framework.

  8. Super pixel density based clustering automatic image classification method

    Science.gov (United States)

    Xu, Mingxing; Zhang, Chuan; Zhang, Tianxu

    2015-12-01

    The image classification is an important means of image segmentation and data mining, how to achieve rapid automated image classification has been the focus of research. In this paper, based on the super pixel density of cluster centers algorithm for automatic image classification and identify outlier. The use of the image pixel location coordinates and gray value computing density and distance, to achieve automatic image classification and outlier extraction. Due to the increased pixel dramatically increase the computational complexity, consider the method of ultra-pixel image preprocessing, divided into a small number of super-pixel sub-blocks after the density and distance calculations, while the design of a normalized density and distance discrimination law, to achieve automatic classification and clustering center selection, whereby the image automatically classify and identify outlier. After a lot of experiments, our method does not require human intervention, can automatically categorize images computing speed than the density clustering algorithm, the image can be effectively automated classification and outlier extraction.

  9. Monte Carlo Simulation and Experimental Characterization of a Dual Head Gamma Camera

    CERN Document Server

    Rodrigues, S; Abreu, M C; Santos, N; Rato-Mendes, P; Peralta, L

    2007-01-01

    The GEANT4 Monte Carlo simulation and experimental characterization of the Siemens E.Cam Dual Head gamma camera hosted in the Particular Hospital of Algarve have been done. Imaging tests of thyroid and other phantoms have been made "in situ" and compared with the results obtained with the Monte Carlo simulation.

  10. Portable gamma camera guidance in sentinel lymph node biopsy: prospective observational study of consecutive cases.

    Science.gov (United States)

    Peral Rubio, F; de La Riva, P; Moreno-Ramírez, D; Ferrándiz-Pulido, L

    2015-06-01

    Sentinel lymph node biopsy is the most important tool available for node staging in patients with melanoma. To analyze sentinel lymph node detection and dissection with radio guidance from a portable gamma camera. To assess the number of complications attributable to this biopsy technique. Prospective observational study of a consecutive series of patients undergoing radioguided sentinel lymph node biopsy. We analyzed agreement between nodes detected by presurgical lymphography, those detected by the gamma camera, and those finally dissected. A total of 29 patients (17 women [62.5%] and 12 men [37.5%]) were enrolled. The mean age was 52.6 years (range, 26-82 years). The sentinel node was dissected from all patients; secondary nodes were dissected from some. In 16 cases (55.2%), there was agreement between the number of nodes detected by lymphography, those detected by the gamma camera, and those finally dissected. The only complications observed were seromas (3.64%). No cases of wound dehiscence, infection, hematoma, or hemorrhage were observed. Portable gamma-camera radio guidance may be of use in improving the detection and dissection of sentinel lymph nodes and may also reduce complications. These goals are essential in a procedure whose purpose is melanoma staging. Copyright © 2014 Elsevier España, S.L.U. and AEDV. All rights reserved.

  11. A state-of-the-art report on the laser decontamination and gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chul Yong; Ahn, B. G.; Shim, J. B.; Won, H. J.; Lee, B. J.; Oh, W. Z

    1997-11-01

    Survey on the development status has been performed on the laser as the device of a radioactive surface decontamination and gamma camera as the device of a contamination measurement. The laser is directly applied to a radioactive contamination on the metal or the concrete surface, then the contamination is removed. Its method has the follow advantages; noncontact method, selective removal of contamination area, negligible amounts of additional waste generated. Laser cleaning process is completed at a cooling state before waste generated. Laser cleaning process is completed at a cooling state before the heat wave propagate to substrate and the contamination material is filtered by the suction device. The gamma camera show a contaminated nuclide and pattern with 2-dimension by remote measurement. The gamma camera is consist of 3 part; collimated radiation measurement part, CCTV image process part, distance measurement part. Therefore, if a radiation position and level are defined by the gamma camera and the laser device is used with remote control, it is very useful at decontamination and decommissioning of the nuclear facility. (author). 44 refs., 4 tabs., 34 figs

  12. Gamma camera imaging for studying intestinal absorption and whole-body distribution of selenomethionine

    DEFF Research Database (Denmark)

    Madsen, Jan L.; Sjögreen-Gleisner, Katarina; Elema, Dennis Ringkjøbing

    2014-01-01

    Se metabolism in humans is not well characterised. Currently, the estimates of Se absorption, whole-body retention and excretion are being obtained from balance and tracer studies. In the present study, we used gamma camera imaging to evaluate the whole-body retention and distribution of radiolab......Se metabolism in humans is not well characterised. Currently, the estimates of Se absorption, whole-body retention and excretion are being obtained from balance and tracer studies. In the present study, we used gamma camera imaging to evaluate the whole-body retention and distribution...... of radiolabelled selenomethionine (SeMet), the predominant form of Se present in foods. A total of eight healthy young men participated in the study. After consumption of a meal containing 4MBq [75Se]L-SeMet ([75Se]SeMet), whole-body gamma camera scanning was performed for 45 min every hour over a 6 h period......]SeMet was retained within the body after 7 d. In contrast, the measured excretion in urine and faeces for the 7 d period was 8•2 (SD 1•1)% of the activity. Time–activity curves were generated for the whole body, stomach, liver, abdomen (other than the stomach and the liver), brain and femoral muscles. Gamma camera...

  13. Split Renal Function in Patients with Suspected Renal Artery Stenosis: a Comparison between Gamma Camera Renography and Two Methods of Measurement with Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerkman, H.; Ekloef, H.; Wadstroem, J.; Andersson, L.G.; Nyman, R.; Magnusson, A. [Uppsala Univ. (Sweden). Depts. of Oncology, Radiology and Clinical Immunology

    2006-02-15

    Purpose: To validate a method for calculating split renal function from computed tomography (CT) compared with gamma camera renography, and to test a new method for the measurement based on a volume-rendering technique. Material and Methods: Thirty-eight patients, aged 65.7{+-}11.6 (range 37.8-82.1) years, who had undergone both CT angiography and gamma camera renography for a suspected renal artery stenosis were included in this study. Split renal function was calculated from the CT examinations by measuring area and mean attenuation in the image slices of the kidneys, and also by measuring volume and mean attenuation from a 3D reconstruction of the kidneys. Gamma camera renography with 99m Tc-MAG3 with or without captopril enhancement was used as a reference. Results: The 2D CT method had good correlation with renography (r = 0.93). Mean difference was 4.7{+-}3.6 (0-12) percentage points per kidney. There was also excellent correlation between the two CT methods (r = 1.00). Conclusion: CT is equivalent to renography in determining split renal function, and the measurement from the CT examination can be made more quickly and equally accurately with a 3D technique.

  14. First operation of a pixel imaging matrix based on DEPFET pixels

    CERN Document Server

    Fischer, P; Klein, P; Löcker, M; Lutz, Gerhard; Neeser, W; Strüder, L; Wermes, N

    2000-01-01

    In the DEPFET pixel concept the detected incident radiation is directly sensed and amplified by a JFET integrated in every pixel cell. While the DEPFET detector principle has already been demonstrated previously on single pixel structures, we present here the first successful operation of a large $32 \\times 32$ DEPFET pixel matrix as an imaging device. The matrix has been exposed to 60 keV gamma rays of a $^{241}$Am source and has been scanned using an IR laser. The principle of operation as well as the charge collection in the structure and possible improvements are discussed.

  15. Level-1 pixel based tracking trigger algorithm for LHC upgrade

    CERN Document Server

    Moon, Chang-Seong

    2015-01-01

    The Pixel Detector is the innermost detector of the tracking system of the Compact Muon Solenoid (CMS) experiment at CERN Large Hadron Collider (LHC). It precisely determines the interaction point (primary vertex) of the events and the possible secondary vertexes due to heavy flavours ($b$ and $c$ quarks); it is part of the overall tracking system that allows reconstructing the tracks of the charged particles in the events and combined with the magnetic field to measure their impulsion. The pixel detector allows measuring the tracks in the region closest to the interaction point. The Level-1 (real-time) pixel based tracking trigger is a novel trigger system that is currently being studied for the LHC upgrade. An important goal is developing real-time track reconstruction algorithms able to cope with very high rates and high flux of data in a very harsh environment. The pixel detector has an especially crucial role in precisely identifying the primary vertex of the rare physics events from the large pile-up (P...

  16. Hybrid Predictor and Field-Biased Context Pixel Selection Based on PPVO

    OpenAIRE

    Hongyin Xiang; Jinsha Yuan; Sizu Hou

    2016-01-01

    Most pixel-value-ordering (PVO) predictors generated prediction-errors including −1 and 1 in a block-by-block manner. Pixel-based PVO (PPVO) method provided a novel pixel scan strategy in a pixel-by-pixel way. Prediction-error bin 0 is expanded for embedding with the help of equalizing context pixels for prediction. In this paper, a PPVO-based hybrid predictor (HPPVO) is proposed as an extension. HPPVO predicts pixel in both positive and negative orientations. Assisted by expansion bins selec...

  17. Image Encryption based on the RGB PIXEL Transposition and Shuffling

    Directory of Open Access Journals (Sweden)

    Quist Aphetsi Kester

    2013-06-01

    Full Text Available Privacy is one of the key issues information Security addresses. Through encryption one can prevent a third party from understanding raw data during signal transmission. The encryption methods for enhancing the security of digital contents has gained high significance in the current era of breach of security and misuse of the confidential information intercepted and misused by the unauthorized parties. This paper sets out to contribute to the general body of knowledge in the area of cryptography application and by developing a cipher algorithm for image encryption of m*n size by shuffling the RGB pixel values. The algorithm ultimately makes it possible for encryption and decryption of the images based on the RGB pixel. The algorithm was implemented using MATLAB.

  18. Analytical and experimental FWHM of a gamma camera: theoretical and practical issues

    OpenAIRE

    Diego Cecchin; Davide Poggiali; Lucia Riccardi; Paolo Turco; Franco Bui; Stefano De Marchi

    2015-01-01

    Introduction. It is well known that resolution on a gamma camera varies as a function of distance, scatter and the camera?s characteristics (collimator type, crystal thickness, intrinsic resolution etc). Manufacturers frequently provide only a few pre-calculated resolution values (using a line source in air, 10?15 cm from the collimator surface and without scattering). However, these are typically not obtained in situations resembling a clinical setting. From a diagnostic point of view, it is...

  19. Algorithms of Coordinates Scintillations Calculation in the Gamma-Camera Detector

    Directory of Open Access Journals (Sweden)

    G.A. Polyakov

    2010-01-01

    Full Text Available The methods and algorithms of scintillation coordinates calculation in gamma-camera position-sensitive detector are considered in the paper. The results of numerical model experiments, which were carried out for clearing-up of relative operating speed of different coordinate calculation methods, are presented. The analysis of obtained results was carried out for determination of perspective for application algorithms and likelihood methods.

  20. SU-E-E-06: Teaching About the Gamma Camera and Ultrasound Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, M; Spiro, A [Loyola University Maryland, Baltimore, Maryland (United States); Vogel, R [Iowa Doppler Products, Iowa City, Iowa (United States); Donaldson, N; Gosselin, C [Rockhurst University, Kansas City, MO (United States)

    2015-06-15

    Purpose: Instructional modules on applications of physics in medicine are being developed. The target audience consists of students who have had an introductory undergraduate physics course. This presentation will concentrate on an active learning approach to teach the principles of the gamma camera. There will also be a description of an apparatus to teach ultrasound imaging. Methods: Since a real gamma camera is not feasible in the undergraduate classroom, we have developed two types of optical apparatus that teach the main principles. To understand the collimator, LEDS mimic gamma emitters in the body, and the photons pass through an array of tubes. The distance, spacing, diameter, and length of the tubes can be varied to understand the effect upon the resolution of the image. To determine the positions of the gamma emitters, a second apparatus uses a movable green laser, fluorescent plastic in lieu of the scintillation crystal, acrylic rods that mimic the PMTs, and a photodetector to measure the intensity. The position of the laser is calculated with a centroid algorithm.To teach the principles of ultrasound imaging, we are using the sound head and pulser box of an educational product, variable gain amplifier, rotation table, digital oscilloscope, Matlab software, and phantoms. Results: Gamma camera curriculum materials have been implemented in the classroom at Loyola in 2014 and 2015. Written work shows good knowledge retention and a more complete understanding of the material. Preliminary ultrasound imaging materials were run in 2015. Conclusion: Active learning methods add another dimension to descriptions in textbooks and are effective in keeping the students engaged during class time. The teaching apparatus for the gamma camera and ultrasound imaging can be expanded to include more cases, and could potentially improve students’ understanding of artifacts and distortions in the images.

  1. Calculation of renal depth by conjugate-view method using dual-head gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Mi; Suh, Tae Suk; Choe, Bo Young; Chung, Yong An; Kim, Sung Hoon; Chung, Soo Kyo; Lee, Hyoung Koo [College of Medicine, The Catholic Univ. of Korea, Seoul (Korea, Republic of)

    2001-12-01

    In this study, we developed a new method for the determination of renal depth with anterior and posterior renal scintigrams in a dual-head gamma camera, considering the attenuation factor e{sup -{mu}}{sup x} of the conjugate-view method. We developed abdomen and kidney phantoms to perform experiments using Technetium-99m dimercaptosuccinic acid ({sup 99m}Tc-DMSA). The phantom images were obtained by dual-head gamma camera equipped with low-energy, high-resolution, parallel-hole collimators (ICONf, Siemens). The equation was derived from the linear integration of emission {gamma}-ray considering attenuation from the posterior abdomen to the anterior abdomen phantom surface. The program for measurement was developed by Microsoft Visual C++ 6.0. Renal depths of the phantoms were derived from the derived equations and compared with the exact geometrical values. Differences between the measured and the calculated values were the range of 0.1 to 0.7 cm (0.029{+-} 0.15 cm, mean {+-}S. D.). The present study showed that the use of the derived equations for renal depth measurement, combined with quantitative planar imaging using duel-head gamma camera, could provide more accurate results for individual variation than the conventional method.

  2. Radioguided occult lesion localisation in breast cancer using an intraoperative portable gamma camera: first results

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, P. [Hospital Sant Pau, Nuclear Medicine Department, Barcelona (Spain); Vidal-Sicart, S.; Pavia, J.; Pons, F. [University of Barcelona, Nuclear Medicine Department, Hospital Clinic, Barcelona (Spain); Institut d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona (Spain); Zanon, G. [University of Barcelona, Obstetrics and Gynaecology Department, Hospital Clinic, Barcelona (Spain); Roe, N.; Rubi, S. [University of Barcelona, Nuclear Medicine Department, Hospital Clinic, Barcelona (Spain); Lafuente, S. [Hospital Joan XXIII, Nuclear Medicine Department, Tarragona (Spain)

    2008-02-15

    The role of the radioguided occult lesion localisation (ROLL) technique in breast cancer has been increasing in recent years. One of the important drawbacks of such a technique is radiotracer spillage within the mammary gland that makes the precise lesion resection difficult, and this requires the use of a hook-wire collocation to reach the lesion. The possibility of obtaining an intraoperative image of the specimen could help to confirm whether the lesion is correctly removed. Some types of portable gamma cameras have been designed, but up to now, intraoperative use has been confined to surgery of parathyroid adenomas and sentinel lymph node location. The aim of the study was to value the usefulness of an intraoperative gamma camera to assess the resection of non-palpable breast lesions. The study involved 42 women diagnosed with non-palpable early breast cancer. Lymphoscintigraphy was performed on the day before surgery by injection of {sup 99m}Tc-labelled nanocolloid. During surgery a gamma probe was used to guide the surgeon, and afterwards images of the surgical bed and the tumoral specimen were acquired by means of a portable gamma camera, fitted with a pinhole collimator. A {sup 99m}Tc pointer was used to draw an outline image around the specimen. On lymphoscintigraphy, radiotracer was concentrated in 31 cases. During surgery, all lesions were removed. In the images acquired by the portable gamma camera, the lesion was centred inside the surgical specimen in 23 of 42 cases, non-centred in 15 and in contact in 4 cases. Congruence of 60% was found between the intraoperative images and the histopathological results. The posterior margin was the most frequently involved. The whole acquisition time for the tumoral specimen with its margins was 5 min at most. The use of portable gamma cameras in theatre is in an early phase. The short period of time required during the surgical procedure will allow the surgical team to improve this technique until it can replace

  3. Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

    Energy Technology Data Exchange (ETDEWEB)

    Thil, Ch., E-mail: christophe.thil@ziti.uni-heidelberg.d [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Baron, A.Q.R. [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Fajardo, P. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France); Fischer, P. [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Graafsma, H. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Rueffer, R. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France)

    2011-02-01

    The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm{sup 2} active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280{mu}mx280{mu}m size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

  4. Pixel Based Off-line Signature Verification System

    Directory of Open Access Journals (Sweden)

    Anik Barua

    2015-01-01

    Full Text Available The verification of handwritten signatures is one of the oldest and the most popular authentication methods all around the world. As technology improved, different ways of comparing and analyzing signatures become more and more sophisticated. Since the early seventies, people have been exploring how computers can fully take over the task of signature verification and tried different methods. However, none of them is satisfactory enough and time consuming too. Therefore, our proposed pixel based offline signature verification system is one of the fastest and easiest ways to authenticate any handwritten signature we have ever found. For signature acquisition, we have used scanner. Then we have divided the signature image into 2D array and calculated the hexadecimal RGB value of each pixel. After that, we have calculated the total percentage of matching. If the percentage of matching is more than 90, the signature is considered as valid otherwise invalid. We have experimented on more than 35 signatures and the result of our experiment is quite impressive. We have made the whole system web based so that the signature can be verified from anywhere. The average execution time for signature verification is only 0.00003545 second only.

  5. Digital image restoration based on pixel simultaneous detection probabilities

    CERN Document Server

    Grabskii, V

    2008-01-01

    Here an image restoration on the basis of pixel simultaneous detection probabilities (PSDP) is proposed. These probabilities can be precisely determined by means of correlations measurement [NIMA 586 (2008) 314-326]. The proposed image restoration is based on the solution of matrix equation. Non-zero elements of Toeplitz block matrix with ones on the main diagonal, is determined using PSDP. The number of non zero descending diagonals depends on the detector construction and is not always smaller than 8. To solve the matrix equation, the Gaussian elimination algorithm is used. The proposed restoration algorithm is studied by means of the simulated images (with and without additive noise using PSDP for General Electric Senographe 2000D mammography device detector) and a small area (160x160 pixels) of real images acquired by the above mentioned device. The estimation errors of PSDP and the additive noise magnitude permits to restore images with the precision better than 2% for the above mentioned detector. The a...

  6. Single photon emission computed tomography of the brain with a rotating gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Biersack, H.J.; Knopp, R.; Winkler, C.; Wappenschmidt, J.

    1981-08-01

    In 471 patients SPECT of the brain was performed in addition to conventional serial brain scintigraphy using a rotating gamma camera (GAMMATOME T 9000). 23 patients had tumorous lesions, 26 had vascular lesions, and 422 patients revealed normal brain findings. 5 of the 23 patients with tumorous lesion and 5 of the 12 patients with vascular lesion (anamnesis shorter than 4 weeks) showed positive SPECT results but false negative conventional brain scans. Specificity could be improved up to 98% (412 out of 422 patients) using SPECT and conventional scintigraphy.

  7. Hydra phantom applicability for carrying out tests of field uniformity in gamma cameras; Aplicabilidade do fantoma hydra para realizacao dos testes de uniformidade de campo em gama camaras

    Energy Technology Data Exchange (ETDEWEB)

    Aragao Filho, Geraldo L., E-mail: geraldo_lemos10@hotmail.com [Centro de Medicina Nuclear de Pernambuco (CEMUPE), Recife, PE (Brazil); Oliveira, Alex C.H., E-mail: oliveira_ach@yahoo.com [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Lopes Filho, Ferdinand J.; Vieira, Jose W., E-mail: ferdinand.lopes@oi.com.br, E-mail: jose-wilson59@live.com [Instituto Federal de Pernambuco (IFPE), Recife, PE (Brazil)

    2014-07-01

    Nuclear Medicine is a medical modality that makes use of radioactive material 'in vivo' in humans, making them a temporary radioactive source. The radiation emitted by the patient's body is detected by a specific equipment, called a gamma camera, creates an image showing the spatial and temporal biodistribution of radioactive material administered to the patient. Therefore, it's of fundamental importance a number of specific measures to make sure that procedure be satisfactory, called quality control. To Nuclear Medicine, quality control of gamma camera has the purpose of ensuring accurate scintillographic imaging, truthful and reliable for the diagnosis, guaranteeing visibility and clarity of details of structures, and also to determine the frequency and the need for preventive maintenance of equipment. To ensure the quality control of the gamma camera it's necessary to use some simulators, called phantom, used in Nuclear Medicine to evaluate system performance, system calibration and simulation of injuries. The goal of this study was to validate a new simulator for nuclear medicine, the Hydra phantom. The phantom was initially built for construction of calibration curves used in radiotherapy planning and quality control in CT. It has similar characteristics to specific phantoms in nuclear medicine, containing inserts and water area. Those inserts are regionally sourced materials, many of them are already used in the literature and based on information about density and interaction of radiation with matter. To verify its efficiency in quality control in Nuclear Medicine, was performed a test for uniformity field, one of the main tests performed daily, so we can verify the ability of the gamma camera to reproduce a uniform distribution of the administered activity in the phantom, been analysed qualitatively, through the image, and quantitatively, through values established for Central Field Of View (CFOV) and Useful Field Of View (UFOV

  8. An operative gamma camera for sentinel lymph node procedure in case of breast cancer

    CERN Document Server

    Salvador, S; Mathelin, C; Guyonne, J; Huss, D

    2007-01-01

    Large field of view gamma cameras are widely used to perform lymphoscintigraphy in the sentinel lymph nodes (SLN) procedure in case of breast cancer. However, they are not specified for this application and their sizes do not enable their use in the operative room to control the excision of the all SLN. We present the results obtained with a prototype of a new mini gamma camera developed especially for the operative lymphoscintigraphy of the axillary area in case of breast cancer. This prototype is composed of 10 mm thick parallel lead collimator, a 2 mm thick GSO:Ce inorganic scintillating crystal from Hitachi and a Hamamatsu H8500 flat panel multianode (64 channels) photomultiplier tube (MAPMT) equipped with a dedicated electronics. Its actual field of view is 50 × 50mm2. The gamma interaction position in the GSO scintillating plate is obtained by calculating the center of gravity of the fired MAPMT channels. The measurements performed with this prototype demonstrate the usefulness of this mini gamma camer...

  9. Biodistribution of liposomal {sup 131}I-VIP in rat using gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Refai, Essam; Jonsson, Cathrine; Andersson, Mats; Jacobsson, Hans; Larsson, Stig; Kogner, Per; Hassan, Moustapha E-mail: hassan@algonet.se

    1999-11-01

    Vasoactive intestinal peptide (VIP), a 28 amino-acid peptide was labeled with {sup 131}I and encapsulated into liposomes. {sup 131}I-VIP or liposomal {sup 131}I -VIP was administered intravenously into the rats. The distribution was studied by a gamma camera and established by counting the radioactivity in the removed organs. The elimination half-life for the liposomal {sup 131}I-VIP in both blood and lungs was significantly longer (5.29 and 9.28 min, respectively) than that obtained after the administration of {sup 131}I-VIP (0.62 and 3.18 min, respectively). Dynamic scans using a gamma camera after the administration of liposomal {sup 131}I-VIP showed a higher uptake of the liposomal form into the lungs compared with {sup 131}I-VIP. The lack of VIP in asthmatics has been shown in previous studies. However, the clinical investigations using VIP were disappointing most probably due to the rapid degradation of the peptide in the bronchial tract. This in fact is supported by our previous study, in which we demonstrated that VIP had a half-life of 0.45 min in blood. We conclude that the encapsulation of VIP in liposomes prolongs its elimination half-life in plasma and enhances its uptake in lungs. This observation may increase the clinical use of VIP in both diagnostic and therapy.

  10. Object Based and Pixel Based Classification Using Rapideye Satellite Imager of ETI-OSA, Lagos, Nigeria

    OpenAIRE

    Esther Oluwafunmilayo Makinde; Ayobami Taofeek Salami; James Bolarinwa Olaleye; Oluwapelumi Comfort Okewusi

    2016-01-01

    Several studies have been carried out to find an appropriate method to classify the remote sensing data. Traditional classification approaches are all pixel-based, and do not utilize the spatial information within an object which is an important source of information to image classification. Thus, this study compared the pixel based and object based classification algorithms using RapidEye satellite image of Eti-Osa LGA, Lagos. In the object-oriented approach, the image was segmented to homog...

  11. Performance of cardiac cadmium-zinc-telluride gamma camera imaging in coronary artery disease: a review from the cardiovascular committee of the European Association of Nuclear Medicine (EANM)

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, Denis [CHU Caen and Normandy University, Department of Nuclear Medicine, Caen (France); Normandy University, Caen (France); Marie, Pierre-Yves [University of Lorraine, Faculty of Medicine, Nancyclotep Experimental Imaging Platform, Nancy (France); University of Lorraine, Faculty of Medicine, CHU Nancy, Department of Nuclear Medicine, Nancy (France); University of Lorraine, Faculty of Medicine, Nancy (France); Ben-Haim, Simona [University College London, University College Hospital, Institute of Nuclear Medicine, London (United Kingdom); Chaim Sheba Medical Center, Department of Nuclear Medicine, Ramat Gan (Israel); Rouzet, Francois [University Hospital of Paris-Bichat, UMR 1148, Inserm et Paris Diderot-Paris 7 University Paris, Department of Nuclear Medicine, Paris (France); UMR 1148, Inserm and Paris Diderot-Paris 7 University Paris, Paris (France); Songy, Bernard [Centre Cardiologique du Nord, Saint-Denis (France); Giordano, Alessandro [Institute of Nuclear Medicine, Catholic University of Sacred Heart, Largo A. Gemelli, Department of Bioimages and Radiological Sciences, Rome (Italy); Gimelli, Alessia [Fondazione Toscana Gabriele Monasterio, Pisa (Italy); Hyafil, Fabien [Bichat University Hospital, Assistance Publique - Hopitaux de Paris, UMR 1148, Inserm and Paris Diderot-Paris 7 University, Department of Nuclear Medicine, Paris (France); Sciagra, Roberto [University of Florence, Nuclear Medicine Unit, Department of Experimental and Clinical Biomedical Sciences, Florence (Italy); Bucerius, Jan [Maastricht University Medical Center, Maastricht University Medical Center, Department of Nuclear Medicine, Maastricht (Netherlands); Maastricht University Medical Center, Cardiovascular Research Institute Maastricht (CARIM), Maastricht (Netherlands); University Hospital RWTH Aachen, Department of Nuclear Medicine, Aachen (Germany); Verberne, Hein J. [Academic Medical Center, Department of Nuclear Medicine, Amsterdam (Netherlands); Slart, Riemer H.J.A. [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen (Netherlands); University of Twente, Faculty of Science and Technology, Department of Biomedical Photonic Imaging, Enschede (Netherlands); Lindner, Oliver [Institute of Radiology, Nuclear Medicine and Molecular Imaging, Heart and Diabetes Center NRW, Bad Oeynhausen (Germany); Collaboration: Cardiovascular Committee of the European Association of Nuclear Medicine (EANM)

    2016-12-15

    The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims (1) to identify the main acquisitions protocols; (2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally (3) to determine the impact of CZT on radiation exposure. (orig.)

  12. Amplifier based broadband pixel for sub-millimeter wave imaging

    Science.gov (United States)

    Sarkozy, Stephen; Drewes, Jonathan; Leong, Kevin M. K. H.; Lai, Richard; Mei, X. B. (Gerry); Yoshida, Wayne; Lange, Michael D.; Lee, Jane; Deal, William R.

    2012-09-01

    Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter wave systems, sub-millimeter wave systems have been hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report a broadband pixel operating from 300 to 340 GHz, biased off a single 2 V power supply. Over this frequency range, the amplifiers provide > 40 dB gain and mobility transistor technology, based on a sub-50 nm gate and indium arsenide composite channel with a projected maximum oscillation frequency fmax>1.0 THz. The first sub-millimeter wave-based images using active amplification are demonstrated as part of the Joint Improvised Explosive Device Defeat Organization Longe Range Personnel Imager Program. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brownout problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.

  13. Object Based and Pixel Based Classification Using Rapideye Satellite Imager of ETI-OSA, Lagos, Nigeria

    Directory of Open Access Journals (Sweden)

    Esther Oluwafunmilayo Makinde

    2016-12-01

    Full Text Available Several studies have been carried out to find an appropriate method to classify the remote sensing data. Traditional classification approaches are all pixel-based, and do not utilize the spatial information within an object which is an important source of information to image classification. Thus, this study compared the pixel based and object based classification algorithms using RapidEye satellite image of Eti-Osa LGA, Lagos. In the object-oriented approach, the image was segmented to homogenous area by suitable parameters such as scale parameter, compactness, shape etc. Classification based on segments was done by a nearest neighbour classifier. In the pixel-based classification, the spectral angle mapper was used to classify the images. The user accuracy for each class using object based classification were 98.31% for waterbody, 92.31% for vegetation, 86.67% for bare soil and 90.57% for Built up while the user accuracy for the pixel based classification were 98.28% for waterbody, 84.06% for Vegetation 86.36% and 79.41% for Built up. These classification techniques were subjected to accuracy assessment and the overall accuracy of the Object based classification was 94.47%, while that of Pixel based classification yielded 86.64%. The result of classification and accuracy assessment show that the object-based approach gave more accurate and satisfying results

  14. Measurement of spleen size using gamma camera scintigraphy in essential thrombocythaemia

    Energy Technology Data Exchange (ETDEWEB)

    Revesz, P. (Department of Medicine, Oestra Hospital, University of Goeteborg, Goeteborg (Sweden)); Carneskog, J.; Wadenvik, H.; Kutti, J. (Haematology Section, Department of Medicine, Sahlgrenska Hospital, University of Goeteborg, Goeteborg (Sweden)); Jarneborn, L. (Department of Clinical Physiology, Oestra Hospital, University of Goeteborg, Goeteborg (Sweden))

    1993-09-01

    By using gamma camera imaging the spleen size was determined in 33 consecutive patients with essential thrombocythaemia (ET) and in 33 consecutive patients with reactive thrombocytosis (RT). All ET patients were newly diagnosed and had not received myelosuppressive treatment prior to study; they all fulfilled the criteria for ET as established by the Polycythemia Vera Study Group. In both posterior and lateral projections, the spleen area in the group of ET patients was significantly larger than in the RT patients. The present study has shown that 39% of ET patients at diagnosis have splenic enlargement. Evaluation of Spleen size is therefore a useful diagnostic test in patients presenting with unexplained thrombocytosis. (au) (15 refs.).

  15. Single-acquisition method for simultaneous determination of extrinsic gamma-camera sensitivity and spatial resolution

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J.A.M. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)], E-mail: a.miranda@portugalmail.pt; Sarmento, S. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Alves, P.; Torres, M.C. [Departamento de Fisica da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Bastos, A.L. [Servico de Medicina Nuclear, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Ponte, F. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)

    2008-01-15

    A new method for measuring simultaneously both the extrinsic sensitivity and spatial resolution of a gamma-camera in a single planar acquisition was implemented. A dual-purpose phantom (SR phantom; sensitivity/resolution) was developed, tested and the results compared with other conventional methods used for separate determination of these two important image quality parameters. The SR phantom yielded reproducible and accurate results, allowing an immediate visual inspection of the spatial resolution as well as the quantitative determination of the contrast for six different spatial frequencies. It also proved to be useful in the estimation of the modulation transfer function (MTF) of the image formation collimator/detector system at six different frequencies and can be used to estimate the spatial resolution as function of the direction relative to the digital matrix of the detector.

  16. Conjugate view gamma camera method for measuring activity in 131{sup I} treatments; Metodo de la imagen conjugada para la cuantificacion de la actividad en tratamientos de 131{sup I}

    Energy Technology Data Exchange (ETDEWEB)

    Barquero Sanz, R.; Placios, A. M.; Perez, D. M.; Tortosa Oliver, R.; Michel, R.

    2012-07-01

    A quantification method is developed to determine 131{sup I} activity and its associated uncertainty using regions of interest from gamma camera images. Inside a neck phantom, a known activity source is introduced to simulate thyroid remainders in thyroid differentiated cancer. The three parameters that define the accuracy of the method are: net count rates in ROI, the air calibration factor of the gamma camera and the attenuation correction factor. In order to obtain net count rates, four methods for background subtraction are tested. The best procedure to follow is based in two energy windows acquisitions, which gives an activity result of 47 {+-} 5 {mu}Ci Bq, in good agreement with the real activity value for the source, 46 {+-} 5 {mu}Ci. (Author) 12 refs.

  17. FDG scan on an ordinary coincidence gamma camera (CDET) -preliminary data in pulmonary or colorectal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Montravers, F.; Grahek, D.; Ghazzar, N.; Younsi, N.; Kerrou, K.; Talbot, J.N. [Hopital Tenon, 75 - Paris (France). Services de Medecine Nucleaire; Wartski, M.; Zerbib, E. [Hopital Marie Lannelongue Le Plessis Robinson (France); Lumbroso, J. [Institut Gustave Roussy Villejuif (France)

    1997-12-31

    Full text. The purpose of this study to evaluate the impact of FDG scan performed on an ordinary CDET gamma camera on the therapeutic management of patients with pulmonary nodules or with suspicion of recurrent colorectal carcinoma. Methods: two tomoscintigrams (thorax and abdomen) were acquired, using a PICKER Prism XP 2000 coincidence gamma camera, 45 m after i.v. injection of 100-150 MBq of {sup 18} F-FDG in fasting patients. The 21 pts were explored in July or August 1997. Preliminary results: among 12 patients with pulmonary nodules, the planed surgery was replaced by chemotherapy after visualization of unknown metastases accumulating FDG in 3 patients. In another one, the high uptake of FDG by a lung nodule which has been known for 6 years, led to surgery and objectivation of an adenocarcinoma. In one case, the absence of FDG uptake corresponded to an abscess (true negative result). In the other 7 patients, the indication of surgery was confirmed but the procedure was modified in 2 cases. In case of suspicion of recurrent colorectal carcinoma (9 patients), the finding of a single focus of FDG uptake whereas CT scan was negative or inconclusive let do the decision of surgery in 3 patients. In one patient with pelvic pain without increase of tumor markers levels and with normal CT scan, a normal FDG scan confirmed the physician`s hypothesis of pain due to the previous therapy but do not recurrence. In one patient, the finding of 3 foci of uptake of FDG whereas CT scan was inconclusive confirmed the indication of chemotherapy. In 2 patients with FDG abdominal foci without morphologic abnormalities, the therapeutic strategy is not yet decided in 2 patients, no foci could be found. In conclusion, these preliminary results show that FDG scan has provided a help to the physician indecision-making for therapeutic strategy in 8 patients on 21 (38%) and a help to the surgeon in 2 more cases (48% as a whole)

  18. Performance of a small CdTe gamma camera for radio-guided surgery

    Science.gov (United States)

    Tsuchimochi, Makoto; Sakahara, Harmui; Hayama, Kazuhide; Funaki, Minoru; Shirahata, T.; Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar

    2001-12-01

    Sentinel lymph node biopsy has been shown to be highly accurate for detecting metastatic diseases, such as melanoma and breast cancer. Gamma probes that measure only the relative presence of radioactivity are commonly used to identify sentinel lymph nodes. We have developed a small semiconductor gamma camera (SSGC) that allows the size, shape, and location of the target tissues to be visualized. The purpose of this study is to characterize the performance of the SSGC for radioguided surgery of metastatic lesions and for diagnosing other diseases amenable to the smaller- format associated with this prototype imaging system. Methods & Design: The detector head was comprised of a 32 x 32 Cadmium Telluride semiconductor array and application- specific integrated circuit (ASIC) with a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mm x 166 mm x 65 mm. The effective visual field was 44.8 mm x 44.8 mm. Two spherical 5 mm diameter Tc-99m radioactive sources having activities of 0.15 MBq and 100 MBq were used to simulate sentinel lymph nodes and injection site. The relative detectability of these foci was compared using the new detector and a conventional scintillation camera. Use of the prototype was also explored on patients in a variety of clinical applications. Results: the SSGC provided better spatial resolution on phantom studies than the conventional gamma camera control. Both foci could be visualized clearly by the SSGC using a 15 second acquisition time, whereas they could not be readily identified using the conventional system under comparable conditions. Preliminary clinical tests of the SSGC were found to be successful in imaging diseases in a variety of tissues including salivary and thyroid glands, temporomandibular joints, and sentinel lymph nodes. Conclusion: The SSGC has significant potential for use in diagnosing diseases and for facilitating subsequent radioguided surgery. (This project was supported by a Grant- in

  19. Simulation of charge transport in pixelated CdTe

    Science.gov (United States)

    Kolstein, M.; Ariño, G.; Chmeissani, M.; De Lorenzo, G.

    2014-12-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated semiconductor technology for nuclear medicine applications to achieve an improved image reconstruction without efficiency loss. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). The design is based on the use of a pixelated CdTe Schottky detector to have optimal energy and spatial resolution. An individual read-out channel is dedicated for each detector voxel of size 1 × 1 × 2 mm3 using an application-specific integrated circuit (ASIC) which the VIP project has designed, developed and is currently evaluating experimentally. The behaviour of the signal charge carriers in CdTe should be well understood because it has an impact on the performance of the readout channels. For this purpose the Finite Element Method (FEM) Multiphysics COMSOL software package has been used to simulate the behaviour of signal charge carriers in CdTe and extract values for the expected charge sharing depending on the impact point and bias voltage. The results on charge sharing obtained with COMSOL are combined with GAMOS, a Geant based particle tracking Monte Carlo software package, to get a full evaluation of the amount of charge sharing in pixelated CdTe for different gamma impact points.

  20. Minimum Distortion Direction Prediction-based Fast Half-pixel Motion Vector Search Algorithm

    Institute of Scientific and Technical Information of China (English)

    DONG Hai-yan; ZHANG Qi-shan

    2005-01-01

    A minimum distortion direction prediction-based novel fast half-pixel motion vector search algorithm is proposed, which can reduce considerably the computation load of half-pixel search. Based on the single valley characteristic of half-pixel error matching function inside search grid, the minimum distortion direction is predicted with the help of comparative results of sum of absolute difference(SAD) values of four integer-pixel points around integer-pixel motion vector. The experimental results reveal that, to all kinds of video sequences, the proposed algorithm can obtain almost the same video quality as that of the half-pixel full search algorithm with a decrease of computation cost by more than 66%.

  1. Data Mining Based Skin Pixel Detection Applied On Human Images: A Study Paper

    Directory of Open Access Journals (Sweden)

    Gagandeep Kaur

    2014-07-01

    Full Text Available Skin segmentation is the process of the identifying the skin pixels in a image in a particular color model and dividing the images into skin and non-skin pixels. It is the process of find the particular skin of the image or video in a color model. Finding the regions of the images in human images to say these pixel regions are part of the image or videos is typically a preprocessing step in skin detection in computer vision, face detection or multi-view face detection. Skin pixel detection model converts the images into appropriate format in a color space and then classification process is being used for labeling of the skin and non-skin pixels. A skin classifier identifies the boundary of the skin image in a skin color model based on the training dataset. Here in this paper, we present the survey of the skin pixel segmentation using the learning algorithms.

  2. Imaging of radiocesium uptake dynamics in a plant body by using a newly developed high-resolution gamma camera.

    Science.gov (United States)

    Kawachi, Naoki; Yin, Yong-Gen; Suzui, Nobuo; Ishii, Satomi; Yoshihara, Toshihiro; Watabe, Hiroshi; Yamamoto, Seiichi; Fujimaki, Shu

    2016-01-01

    We developed a new gamma camera specifically for plant nutritional research and successfully performed live imaging of the uptake and partitioning of (137)Cs in intact plants. The gamma camera was specially designed for high-energy gamma photons from (137)Cs (662 keV). To obtain reliable images, a pinhole collimator made of tungsten heavy alloy was used to reduce penetration and scattering of gamma photons. A single-crystal scintillator, Ce-doped Gd3Al2Ga3O12, with high sensitivity, no natural radioactivity, and no hygroscopicity was used. The array block of the scintillator was coupled to a high-quantum efficiency position sensitive photomultiplier tube to obtain accurate images. The completed gamma camera had a sensitivity of 0.83 count s(-1) MBq(-1) for (137)Cs with an energy window from 600 keV to 730 keV, and a spatial resolution of 23.5 mm. We used this gamma camera to study soybean plants that were hydroponically grown and fed with 2.0 MBq of (137)Cs for 6 days to visualize and investigate the transport dynamics in aerial plant parts. (137)Cs gradually appeared in the shoot several hours after feeding, and then accumulated preferentially and intensively in growing pods and seeds; very little accumulation was observed in mature leaves. Our results also suggested that this gamma-camera method may serve as a practical analyzing tool for breeding crops and improving cultivation techniques resulting in low accumulation of radiocesium into the consumable parts of plants.

  3. Intraoperative radioguidance with a portable gamma camera: a novel technique for laparoscopic sentinel node localisation in urological malignancies

    Energy Technology Data Exchange (ETDEWEB)

    Vermeeren, L.; Valdes Olmos, R.A.; Vogel, W.V.; Sivro, F.; Hoefnagel, C.A. [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Department of Nuclear Medicine, Amsterdam (Netherlands); Meinhardt, W.; Bex, A.; Poel, H.G. van der; Horenblas, S. [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Department of Urology, Amsterdam (Netherlands)

    2009-07-15

    Our aim was to assess the feasibility of intraoperative radioguidance with a portable gamma camera during laparoscopic sentinel node (SN) procedures in urological malignancies. We evaluated the use of the intraoperative portable gamma camera in 20 patients: 16 patients with prostate carcinoma (PCC), 2 patients with renal cell carcinoma (RC) and 2 patients with testicular cancer (TC). Intra/peritumoural injection of {sup 99m}Tc-nanocolloid ({sup 99m}Tc) was followed by planar lymphoscintigraphy, SPECT/CT and marking of SN levels. Before laparoscopy a {sup 125}I seed was fixed on the laparoscopic gamma probe as a pointer of SN seeking. The portable gamma camera was set to display the {sup 99m}Tc signal for SN localisation and the {sup 125}I signal for SN seeking. Matching of these signals on screen indicated exact SN localisation, and consequently this SN was removed. The mean injected dose was 218 MBq in PCC, 228 MBq in RC and 88 MBq in TC. Pelvic SN were visualised in all PCC patients, with uncommonly located SN in seven patients. SN metastases were found in seven patients (one in a uncommonly located SN). Both RC patients and TC patients had para-aortic SN, which were all tumour free. A total of 59 SN were removed. The portable gamma camera enabled real-time SN display/identification in 18 patients (90%). The use of a portable gamma camera in combination with a laparoscopic gamma probe incorporates intraoperative real-time imaging with improved SN identification in urological malignancies. This procedure might also be useful for SN identification of other deep draining malignancies. (orig.)

  4. Denoising of brain MRI images using modified PDE based on pixel similarity

    Science.gov (United States)

    Jin, Renchao; Song, Enmin; Zhang, Lijuan; Min, Zhifang; Xu, Xiangyang; Huang, Chih-Cheng

    2008-03-01

    Although various image denoising methods such as PDE-based algorithms have made remarkable progress in the past years, the trade-off between noise reduction and edge preservation is still an interesting and difficult problem in the field of image processing and analysis. A new image denoising algorithm, using a modified PDE model based on pixel similarity, is proposed to deal with the problem. The pixel similarity measures the similarity between two pixels. Then the neighboring consistency of the center pixel can be calculated. Informally, if a pixel is not consistent enough with its surrounding pixels, it can be considered as a noise, but an extremely strong inconsistency suggests an edge. The pixel similarity is a probability measure, its value is between 0 and 1. According to the neighboring consistency of the pixel, a diffusion control factor can be determined by a simple thresholding rule. The factor is combined into the primary partial differential equation as an adjusting factor for controlling the speed of diffusion for different type of pixels. An evaluation of the proposed algorithm on the simulated brain MRI images was carried out. The initial experimental results showed that the new algorithm can smooth the MRI images better while keeping the edges better and achieve higher peak signal to noise ratio (PSNR) comparing with several existing denoising algorithms.

  5. Hybrid Predictor and Field-Biased Context Pixel Selection Based on PPVO

    Directory of Open Access Journals (Sweden)

    Hongyin Xiang

    2016-01-01

    Full Text Available Most pixel-value-ordering (PVO predictors generated prediction-errors including −1 and 1 in a block-by-block manner. Pixel-based PVO (PPVO method provided a novel pixel scan strategy in a pixel-by-pixel way. Prediction-error bin 0 is expanded for embedding with the help of equalizing context pixels for prediction. In this paper, a PPVO-based hybrid predictor (HPPVO is proposed as an extension. HPPVO predicts pixel in both positive and negative orientations. Assisted by expansion bins selection technique, this hybrid predictor presents an optimized prediction-error expansion strategy including bin 0. Furthermore, a novel field-biased context pixel selection is already developed, with which detailed correlations of around pixels are better exploited more than equalizing scheme merely. Experiment results show that the proposed HPPVO improves embedding capacity and enhances marked image fidelity. It also outperforms some other state-of-the-art methods of reversible data hiding, especially for moderate and large payloads.

  6. CMOS integrator based lock-in pixel for heterodyne interferometry

    NARCIS (Netherlands)

    Soloviev, O.; Vdovin, G.

    2005-01-01

    This article presents a prototype of a CMOS phase sensor for high accuracy (1 Angstrom) heterodyne interferometry. Switched integrators realization of a lock-in pixel for 4-bucket phase detection algorithm is described and illustrated by experimental results. Factors that limit the accuracy of this

  7. Fast Contour-Tracing Algorithm Based on a Pixel-Following Method for Image Sensors.

    Science.gov (United States)

    Seo, Jonghoon; Chae, Seungho; Shim, Jinwook; Kim, Dongchul; Cheong, Cheolho; Han, Tack-Don

    2016-03-09

    Contour pixels distinguish objects from the background. Tracing and extracting contour pixels are widely used for smart/wearable image sensor devices, because these are simple and useful for detecting objects. In this paper, we present a novel contour-tracing algorithm for fast and accurate contour following. The proposed algorithm classifies the type of contour pixel, based on its local pattern. Then, it traces the next contour using the previous pixel's type. Therefore, it can classify the type of contour pixels as a straight line, inner corner, outer corner and inner-outer corner, and it can extract pixels of a specific contour type. Moreover, it can trace contour pixels rapidly because it can determine the local minimal path using the contour case. In addition, the proposed algorithm is capable of the compressing data of contour pixels using the representative points and inner-outer corner points, and it can accurately restore the contour image from the data. To compare the performance of the proposed algorithm to that of conventional techniques, we measure their processing time and accuracy. In the experimental results, the proposed algorithm shows better performance compared to the others. Furthermore, it can provide the compressed data of contour pixels and restore them accurately, including the inner-outer corner, which cannot be restored using conventional algorithms.

  8. A Global-Scale Image Lossless Compression Method Based on QTM Pixels

    Institute of Scientific and Technical Information of China (English)

    SUN Wen-bin; ZHAO Xue-sheng

    2006-01-01

    In this paper, a new predictive model, adapted to QTM (Quaternary Triangular Mesh) pixel compression, is introduced. Our approach starts with the principles of proposed predictive models based on available QTM neighbor pixels. An algorithm of ascertaining available QTM neighbors is also proposed. Then, the method for reducing space complexities in the procedure of predicting QTM pixel values is presented. Next, the structure for storing compressed QTM pixel is proposed. In the end, the experiment on comparing compression ratio of this method with other methods is carried out by using three wave bands data of 1 km resolution of NOAA images in China. The results indicate that: 1) the compression method performs better than any other, such as Run Length Coding, Arithmetic Coding, Huffman Coding, etc; 2) the average size of compressed three wave band data based on the neighbor QTM pixel predictive model is 31.58% of the origin space requirements and 67.5% of Arithmetic Coding without predictive model.

  9. Design Optimization of Pixel Structure for α-Si based Uncooled Infrared Detector

    Directory of Open Access Journals (Sweden)

    Sudha Gupta

    2013-11-01

    Full Text Available In this paper authors present the design and simulation results achieved for pixel structure of amorphous Si (α-Si based bolometer array. Most uncooled IR detectors in the world are based on VOx material. But this is not a standard material in IC technology and has many inherent disadvantages. The α-Si, an alternative material with high TCR is becoming as popular. However, large TCR values, in this material are achieved only in films of high resistivity. To achieve TCR value more than 2.5%/K, α-Si film resistivity is ~ 80 ohms-cm. This gives rise to very large pixel resistance of the order of 100 Mega ohms depending upon the design of the leg structure. This high pixel resistance causes very large noise and hence lower sensitivity. If leg width or membrane thickness is increased in order to reduce the pixel resistance, then this results in higher thermal conductance which also decreases sensitivity. To overcome this problem, pixel structure is so designed that within a pixel, only part of the electrical conduction is through α-Si and rest is through metal. Simulation using Coventorware software has been done to optimize pixel resistance as well as thermal conductance through legs so that maximum sensitivity could be obtained. Optimization is also carried out in order to reduce sensitivity of pixel resistance to variation in material resistivity.

  10. Pixel Detectors

    OpenAIRE

    Wermes, Norbert

    2005-01-01

    Pixel detectors for precise particle tracking in high energy physics have been developed to a level of maturity during the past decade. Three of the LHC detectors will use vertex detectors close to the interaction point based on the hybrid pixel technology which can be considered the state of the art in this field of instrumentation. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as the very harsh...

  11. Neural network based cluster creation in the ATLAS silicon Pixel Detector

    CERN Document Server

    Andreazza, A; The ATLAS collaboration

    2013-01-01

    The read-out from individual pixels on planar semi-conductor sensors are grouped into clusters to reconstruct the location where a charged particle passed through the sensor. The resolution given by individual pixel sizes is significantly improved by using the information from the charge sharing between pixels. Such analog cluster creation techniques have been used by the ATLAS experiment for many years to obtain an excellent performance. However, in dense environments, such as those inside high-energy jets, clusters have an increased probability of merging the charge deposited by multiple particles. Recently, a neural network based algorithm which estimates both the cluster position and whether a cluster should be split has been developed for the ATLAS Pixel Detector. The algorithm significantly reduces ambiguities in the assignment of pixel detector measurement to tracks within jets and improves the position accuracy with respect to standard interpolation techniques by taking into account the 2-dimensional ...

  12. Neural network based cluster creation in the ATLAS silicon Pixel Detector

    CERN Document Server

    Perez Cavalcanti, T; The ATLAS collaboration

    2012-01-01

    The hit signals read out from pixels on planar semi-conductor sensors are grouped into clusters, to reconstruct the location where a charged particle passed through. The resolution of the individual pixel sizes can be improved significantly using the information from the cluster of adjacent pixels. Such analog cluster creation techniques have been used by the ATLAS experiment for many years giving an excellent performance. However, in dense environments, such as those inside high-energy jets, is likely that the charge deposited by two or more close-by tracks merges into one single cluster. A new pattern recognition algorithm based on neural network methods has been developed for the ATLAS Pixel Detector. This can identify the shared clusters, split them if necessary, and estimate the positions of all particles traversing the cluster. The algorithm significantly reduces ambiguities in the assignment of pixel detector measurements to tracks within jets, and improves the positional accuracy with respect to stand...

  13. The review of myocardial positron emission computed tomography and positron imaging by gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Ohtake, Tohru [Tokyo Univ. (Japan). Faculty of Medicine

    1998-04-01

    To measure myocardial blood flow, Nitrogen-13 ammonia, Oxygen-15 water, Rubidium-82 and et al. are used. Each has merit and demerit. By measuring myocardial coronary flow reserve, the decrease of flow reserve during dipyridamole in patients with hypercholesterolemia or diabetes mellitus without significant coronary stenosis was observed. The possibility of early detection of atherosclerosis was showed. As to myocardial metabolism, glucose metabolism is measured by Fluorine-18 fluorodeoxyglucose (FDG), and it is considered as useful for the evaluation of myocardial viability. We are using FDG to evaluate insulin resistance during insulin clamp in patients with diabetes mellitus by measuring glucose utilization rate of myocardium and skeletal muscle. FFA metabolism has been measured by {sup 11}C-palmitate, but absolute quantification has not been performed. Recently the method for absolute quantification was reported, and new radiopharmaceutical {sup 18}F-FTHA was reported. Oxygen metabolism has been estimated by {sup 11}C-acetate. Myocardial viability, cardiac efficiency was evaluated by oxygen metabolism. As to receptor or sympathetic nerve end, cardiac insufficiency or cardiac transplantation was evaluated. Imaging of positron emitting radiopharmaceutical by gamma camera has been performed. Collimator method is clinically useful for cardiac imaging of viability study. (author). 54 refs.

  14. Is gamma-camera imaging of platelet deposition useful to assess the effectiveness of prostacyclin treatment?

    Science.gov (United States)

    Fitscha, P; Kaliman, J; Sinzinger, H

    1984-01-01

    Platelet labeling with 111-In-oxinesulfate allows visualization of platelet deposition in the vascular bed. Scintigraphic studies were performed in 6 patients with "active" (PUR greater than 1.20) and 8 patients with "inactive" (PUR less than 1.20) atherosclerotic lesions of the femoral artery. Platelet deposition was also studied in 11 patients with implanted prosthetic vascular grafts and in 21 patients with an abnormal aneurysm of the aorta. Infusing 5 ng/kg/min PGI2 during 6 hours for 5 days into patients with "active"-atherosclerosis and aneurysms of the aorta resulted in a significant decrease of platelet deposition even after having stopped the infusion. There was no influence of PGI2 on PUR in patients with "inactive" lesions. The group of patients with implanted prosthetic grafts demonstrated also a significant decrease of PUR values during the PGI2-infusion, but reached baseline values soon after stopping the infusion. When platelet deposition is increased gamma-camera imaging provides valuable date on the influence of any kind of therapy on the in-vivo platelet function.

  15. The use of detective quantum efficiency (DQE) in evaluating the performance of gamma camera systems

    Energy Technology Data Exchange (ETDEWEB)

    Starck, Sven-Ake [Department of Hospital Physics, County Hospital Ryhov, Joenkoeping (Sweden); Department of Radiation Physics, Goeteborg University, Goeteborg (Sweden); Baath, Magnus [Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Goeteborg (Sweden); Department of Radiation Physics, Goeteborg University, Goeteborg (Sweden); Carlsson, Sten [Department of Radiology, Uddevalla Hospital, Uddevalla (Sweden); Department of Radiation Physics, Goeteborg University, Goeteborg (Sweden)

    2005-04-07

    The imaging properties of an imaging system can be described by its detective quantum efficiency (DQE). Using the modulation transfer function calculated from measured line spread functions and the normalized noise power spectrum calculated from uniformity images, DQE was calculated with the number of photons emitted from a plane source as a measure for the incoming SNR{sup 2}. Measurements were made with {sup 99m}Tc, using three different pulse height windows at 2 cm and 12 cm depths in water with high resolution and all purpose collimators and with two different crystal thicknesses. The results indicated that at greater depths a 15% window is the best choice. The choice of collimator depends on the details in the organ being investigated. There is a break point at 0.5 cycles cm{sup -1} and 1.2 cycles cm{sup -1} at 12 cm and 2 cm depths, respectively. A difference was found in DQE between the two crystal thicknesses, with a slightly better result for the thick crystal for measurements at 12 cm depth. At 2 cm depth, the thinner crystal was slightly better for frequencies over 0.5 cm{sup -1}. The determination of DQE could be a method to optimize the parameters for different nuclear medicine investigations. The DQE could also be used in comparing different gamma camera systems with different collimators to obtain a figure of merit.

  16. Radioguided Parathyroidectomy with Portable Mini Gamma-Camera for the Treatment of Primary Hyperparathyroidism

    Directory of Open Access Journals (Sweden)

    Claudio Casella

    2015-01-01

    Full Text Available Background. A proper localisation of pathological parathyroid glands is essential for a minimally invasive approach in the surgical treatment of primary hyperparathyroidism (PHP. The recent introduction of portable mini gamma-cameras (pMGCs enabled intraoperative scintigraphic scanning. The aim of our study is to evaluate the efficacy of this new method and compare it with the preoperative localisation surveys. Methods. 20 patients were studied; they were evaluated preoperatively by neck ultrasound and Tc-sestaMIBI-scintigraphy and intraoperatively with the pMGC IP Guardian 2. The results obtained from the three evaluations were compared. Results. The pMGC presented a sensitivity of 95%, a specificity of 98.89%, and a diagnostic accuracy of 98.18%, which were higher than those of preoperative ultrasound (sensitivity 55%; specificity 95%; diagnostic accuracy 87% and scintigraphy with Tc-sestaMIBI (sensitivity 73.68%; specificity 96.05%; diagnostic accuracy 91.58%. Conclusions. The pMGC can be used effectively as an intraoperative method to find the correct location of the pathological parathyroid glands. The pMGC is more reliable than the currently used preoperative and intraoperative localisation techniques.

  17. Fast Contour-Tracing Algorithm Based on a Pixel-Following Method for Image Sensors

    Directory of Open Access Journals (Sweden)

    Jonghoon Seo

    2016-03-01

    Full Text Available Contour pixels distinguish objects from the background. Tracing and extracting contour pixels are widely used for smart/wearable image sensor devices, because these are simple and useful for detecting objects. In this paper, we present a novel contour-tracing algorithm for fast and accurate contour following. The proposed algorithm classifies the type of contour pixel, based on its local pattern. Then, it traces the next contour using the previous pixel’s type. Therefore, it can classify the type of contour pixels as a straight line, inner corner, outer corner and inner-outer corner, and it can extract pixels of a specific contour type. Moreover, it can trace contour pixels rapidly because it can determine the local minimal path using the contour case. In addition, the proposed algorithm is capable of the compressing data of contour pixels using the representative points and inner-outer corner points, and it can accurately restore the contour image from the data. To compare the performance of the proposed algorithm to that of conventional techniques, we measure their processing time and accuracy. In the experimental results, the proposed algorithm shows better performance compared to the others. Furthermore, it can provide the compressed data of contour pixels and restore them accurately, including the inner-outer corner, which cannot be restored using conventional algorithms.

  18. Redundant Discrete Wavelet Transform Based Super-Resolution Using Sub-Pixel Image Registration

    Science.gov (United States)

    2003-03-01

    AFIT/GE/ENG/03-18 REDUNDANT DISCRETE WAVELET TRANSFORM BASED SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION THESIS Daniel L. Ward Second...position of the United States Air Force, Department of Defense, or the United States Government. AFIT/GE/ENG/03-18 REDUNDANT DISCRETE WAVELET TRANSFORM BASED...O3-18 REDUNDANT DISCRETE WAVELET TRANSFORM BASED SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION THESIS Daniel Lee Ward, B.S.E.E. Second

  19. Developing a beta source based setup for pixel sensor characterization

    CERN Document Server

    Schouwenberg, Jeroen

    2014-01-01

    The main goal of this project is to provide mono-energetic minimum ionizing electrons from a $^{90}$Sr source using a magnetic monochromator, and thus provide a useful tool for in-lab sensor characterization. The monochromator is calibrated using a setup, with a heavy inorganic scintillator and a PMT, which has been calibrated with a $^{22}$Na gamma source. The average energy of the electrons as a function of the current in the monochromator coil is found to be $1.38\\pm0.01$ keV/mA, taking into consideration the effect of the magnetic field on the signal of the PMT. For integration into the pixel sensor test bench, scintillator-counters (a plastic scintillator connected to a PMT) are used. Their response to the electron energies is observed to follow a saturation curve, which leads to a more identical response for high energetic electrons. A preliminary pixel sensor test bench has been set up and properties such as voltage and discriminator settings have been studied as well as count rates for coincidence cou...

  20. In vivo animal demonstration of the effect of vasoactive drugs using /sup 195m/Au and gamma camera techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, P.; Bourgeois, F.; Lupo, P.; Vooren, J.P. van; Clercx, C.

    1987-08-01

    /sup 195m/Au, an ultrashort lived (physical half life = 30.5 s), generator produced, radionuclide, has been used in an animal model to study, by gamma camera techniques, the peripheral effects of the vasoactive drugs norepinephrine and sodium nitroprusside systemically administered or epinephrine intraarterially injected, at various concentrations. According to the results obtained by the analysis of time on the proximal and distal parts of the limbs, the well known hemodynamic changes induced by these drugs, vascoconstriction (resulting in a decrease of the distal acitvity recorded), or vasodilatation (shortening the time of radioactivity appearance), could be observed. It is concluded that gamma camera techniques using the ultrashort lived radionuclide /sup 195m/Au allow the in vivo study of the effects of vasoactive drugs in an animal model and potentially in clinical situations.

  1. Urban Image Classification: Per-Pixel Classifiers, Sub-Pixel Analysis, Object-Based Image Analysis, and Geospatial Methods. 10; Chapter

    Science.gov (United States)

    Myint, Soe W.; Mesev, Victor; Quattrochi, Dale; Wentz, Elizabeth A.

    2013-01-01

    Remote sensing methods used to generate base maps to analyze the urban environment rely predominantly on digital sensor data from space-borne platforms. This is due in part from new sources of high spatial resolution data covering the globe, a variety of multispectral and multitemporal sources, sophisticated statistical and geospatial methods, and compatibility with GIS data sources and methods. The goal of this chapter is to review the four groups of classification methods for digital sensor data from space-borne platforms; per-pixel, sub-pixel, object-based (spatial-based), and geospatial methods. Per-pixel methods are widely used methods that classify pixels into distinct categories based solely on the spectral and ancillary information within that pixel. They are used for simple calculations of environmental indices (e.g., NDVI) to sophisticated expert systems to assign urban land covers. Researchers recognize however, that even with the smallest pixel size the spectral information within a pixel is really a combination of multiple urban surfaces. Sub-pixel classification methods therefore aim to statistically quantify the mixture of surfaces to improve overall classification accuracy. While within pixel variations exist, there is also significant evidence that groups of nearby pixels have similar spectral information and therefore belong to the same classification category. Object-oriented methods have emerged that group pixels prior to classification based on spectral similarity and spatial proximity. Classification accuracy using object-based methods show significant success and promise for numerous urban 3 applications. Like the object-oriented methods that recognize the importance of spatial proximity, geospatial methods for urban mapping also utilize neighboring pixels in the classification process. The primary difference though is that geostatistical methods (e.g., spatial autocorrelation methods) are utilized during both the pre- and post

  2. SUB PIXEL IMAGE PROCESSING FOR DISTANCE MEASUREMENT ON THE BASE OF DIGITAL CAMERA

    Directory of Open Access Journals (Sweden)

    V. L. Kozlov

    2012-01-01

    Full Text Available The technique of sub pixel processing of the digital photographic images for precision distances and sizes measurements based on stereogram processing is offered. Experimental results of measuring equipment are presented.

  3. Data Mining Based Skin Pixel Detection Applied On Human Images: A Study Paper

    National Research Council Canada - National Science Library

    Gagandeep Kaur; Seema Pahwa

    2014-01-01

    .... A skin classifier identifies the boundary of the skin image in a skin color model based on the training dataset. Here in this paper, we present the survey of the skin pixel segmentation using the learning algorithms.

  4. Adapting clinical gamma cameras for body monitoring in the event of a large-scale radiological incident.

    Science.gov (United States)

    Scuffham, J W; Yip-Braidley, M; Shutt, A L; Hinton, P J; Nisbet, A; Bradley, D A

    2016-06-06

    After a release of radionuclides, accidental or otherwise, there will be an urgent need to identify members of the general public who have received a significant intake of radioactive material, sufficient to require medical treatment or further investigation. A large number of people could be contaminated in such an incident. For gamma-ray emitting radionuclides this screening could be carried out using gamma camera medical imaging systems, such as those that are present in many large UK hospital sites. By making a number of simple reversible changes such as removal of collimators, these cameras could be employed as useful additional screening instruments as well as an aid in contamination control. A study was carried out to investigate which systems were present in sufficient number to offer wide scale coverage of UK population centres. Nine gamma cameras (eight dual head and one single head) were assessed using point source and bottle mannequin (BOMAB) phantom measurements so that a mathematical model could be developed for use with the MCNPX Monte Carlo radiation transport code. The gamma camera models were assessed for practical seated and supine geometries to give calibration factors for a list of target radionuclides that could be released in a radiological incident. The minimum detectable activities (MDAs) that were achieved for a five minute measurement demonstrated that these systems are sufficiently sensitive to be used for screening of the general public and are comparable to other body monitoring facilities. While gamma cameras have on-board software that are designed for imaging and provide for a gamma-ray energy range suitable for radionuclides for diagnostic imaging (such as (99m)Tc), they are not as versatile as custom-built body monitoring systems.

  5. Change detection of built-up land: A framework of combining pixel-based detection and object-based recognition

    Science.gov (United States)

    Xiao, Pengfeng; Zhang, Xueliang; Wang, Dongguang; Yuan, Min; Feng, Xuezhi; Kelly, Maggi

    2016-09-01

    This study proposed a new framework that combines pixel-level change detection and object-level recognition to detect changes of built-up land from high-spatial resolution remote sensing images. First, an adaptive differencing method was designed to detect changes at the pixel level based on both spectral and textural features. Next, the changed pixels were subjected to a set of morphological operations to improve the completeness and to generate changed objects, achieving the transition of change detection from the pixel level to the object level. The changed objects were further recognised through the difference of morphological building index in two phases to indicate changed objects on built-up land. The transformation from changed pixels to changed objects makes the proposed framework distinct with both the pixel-based and the object-based change detection methods. Compared with the pixel-based methods, the proposed framework can improve the change detection capability through the transformation and successive recognition of objects. Compared with the object-based method, the proposed framework avoids the issue of multitemporal segmentation and can generate changed objects directly from changed pixels. The experimental results show the effectiveness of the transformation from changed pixels to changed objects and the successive object-based recognition on improving the detection accuracy, which justify the application potential of the proposed change detection framework.

  6. Modelling image profiles produced with a small field of view gamma camera with a single pinhole collimator

    Science.gov (United States)

    Bugby, S. L.; Lees, J. E.; Perkins, A. C.

    2012-11-01

    Gamma cameras making use of parallel-hole collimators have a long history in medical imaging. Pinhole collimators were used in the original gamma camera instruments and have been used more recently in dedicated organ specific systems, intraoperative instruments and for small animal imaging, providing higher resolution over a smaller field of view than the traditional large field of view systems. With the resurgence of interest in the use of pinhole collimators for small field of view (SOV) medical gamma cameras, it is important to be able to accurately determine their response under various conditions. Several analytical approaches to pinhole response have been reported in the literature including models of 3D pinhole imaging systems. Success has also been reported in the use of Monte Carlo simulations; however this approach can require significant time and computing power. This report describes a 2D model that was used to investigate some common problems in pinhole imaging, the variation in resolution over the field of view and the use of `point' sources for quantifying pinhole response.

  7. NOTE: Changes in the energy response of a dedicated gamma camera after exposure to a high-flux irradiation

    Science.gov (United States)

    Matheoud, Roberta; Zito, Felicia; Canzi, Cristina; Voltini, Franco; Gerundini, Paolo

    1999-06-01

    This work reports the effects of the gain variation of the photomultiplier tubes (PMTs) observed on a cardiac dedicated gamma camera after accidental high-flux irradiation. One detector of this dual-headed 90°-fixed gamma camera was accidentally left uncollimated during a quality assurance procedure on the other detector with a 57Co flood source (259 MBq) and received a non-uniform high flux of 1.9-0.6 Mcps over 25 000 mm2 areas for about 30 min. To evaluate the severity and the duration of the perturbation effect on the energy response of the detector, the photopeak position was monitored for about 1 month with a 99mTc point source. The 140 keV photopeak shifted to 158 keV soon after irradiation, reached the correct position after 9 days and moved to a stable value of 132 keV after 15 days. Afterwards, a new energy calibration reset the photopeak position at 140 keV and the correct energy response of the gamma camera. This experience suggests that particular care should be taken to avoid exposures to high radiation fluxes that induce persistent gain shifts on the PMTs of this system.

  8. A level-1 pixel based track trigger for the CMS HL-LHC upgrade

    CERN Document Server

    Moon, Chang-Seong

    2016-01-01

    We present feasibility studies to investigate the performance and interest of a Level-1 trigger based on pixels. The Level-1 (real-time) pixel based tracking trigger is a novel trigger system that is based on real-time track reconstruction algorithms able to cope with very high rates and high flux of data in a very harsh environment. The pixel detector has an especially crucial role in precisely identifying the primary vertex of rare physics events from the large pile-up of events. The goal of adding the pixel information already at the real-time level of the selection is to help reducing the total Level-1 trigger rate while keeping a high selection capability. This is quite an innovative and challenging objective for the upgrade of the experiments for the High Luminosity LHC.

  9. Toward Parts-Based Scene Understanding with Pixel-Support Parts-Sparse Pictorial Structures

    CERN Document Server

    Corso, Jason J

    2011-01-01

    Scene understanding remains a significant challenge in the computer vision community. The visual psychophysics literature has demonstrated the importance of interdependence among parts of the scene. Yet, the majority of methods in computer vision remain local. Pictorial structures have arisen as a fundamental parts-based model for some vision problems, such as articulated object detection. However, the form of classical pictorial structures limits their applicability for global problems, such as semantic pixel labeling. In this paper, we propose an extension of the pictorial structures approach, called pixel-support parts-sparse pictorial structures, or PS3, to overcome this limitation. Our model extends the classical form in two ways: first, it defines parts directly based on pixel-support rather than in a parametric form, and second, it specifies a space of plausible parts-based scene models and permits one to be used for inference on any given image. PS3 makes strides toward unifying object-level and pixel...

  10. A level-1 pixel based track trigger for the CMS HL-LHC upgrade

    CERN Document Server

    CMS Collaboration

    2016-01-01

    We present feasibility studies to investigate the performances and interest of a Level-1 trigger based on pixels. The Level-1 (real-time) pixel based tracking trigger is a novel trigger system that is based on the real-time track reconstruction algorithms able to cope with very high rates and high flux of data in a very harsh environment. The pixel detector has an especially crucial role in precisely identifying the primary vertex of the rare physics events from the large pile-up (PU) of events. The goal of adding the pixel information already at the real-time level of the selection is to help reducing the total level-1 trigger rate while keeping an high selection capability. This is quite an innovative and challenging objective for the experiments upgrade for the High Luminosity LHC (HL-LHC).

  11. Fast pixel-based optical proximity correction based on nonparametric kernel regression

    Science.gov (United States)

    Ma, Xu; Wu, Bingliang; Song, Zhiyang; Jiang, Shangliang; Li, Yanqiu

    2014-10-01

    Optical proximity correction (OPC) is a resolution enhancement technique extensively used in the semiconductor industry to improve the resolution and pattern fidelity of optical lithography. In pixel-based OPC (PBOPC), the layout is divided into small pixels, which are then iteratively modified until the simulated print image on the wafer matches the desired pattern. However, the increasing complexity and size of modern integrated circuits make PBOPC techniques quite computationally intensive. This paper focuses on developing a practical and efficient PBOPC algorithm based on a nonparametric kernel regression, a well-known technique in machine learning. Specifically, we estimate the OPC patterns based on the geometric characteristics of the original layout corresponding to the same region and a series of training examples. Experimental results on metal layers show that our proposed approach significantly improves the speed of a current professional PBOPC software by a factor of 2 to 3, and may further reduce the mask complexity.

  12. Potential role of a new hand-held miniature gamma camera in performing minimally invasive parathyroidectomy

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Joaquin; Lledo, Salvador [University of Valencia, Clinic University Hospital, Department of Surgery, Valencia (Spain); Ferrer-Rebolleda, Jose [Clinic University Hospital, Department of Nuclear Medicine, Valencia (Spain); Cassinello, Norberto [Clinic University Hospital, Unit of Endocrinologic and Bariatric Surgery, Valencia (Spain)

    2007-02-15

    Sestamibi scans have increased the use of minimally invasive parathyroidectomy (MIP) to treat primary hyperparathyroidism (PHPT) when caused by a parathyroid single adenoma. The greatest concern for surgeons remains the proper identification of pathological glands in a limited surgical field. We have studied the usefulness of a new hand-held miniature gamma camera (MGC) when used intraoperatively to locate parathyroid adenomas. To our knowledge this is the first report published on this subject in the scientific literature. Five patients with PHPT secondary to a single adenoma, positively diagnosed by preoperative sestamibi scans, underwent a MIP. A gamma probe for radioguided surgery and the new hand-held MGC were used consecutively to locate the pathological glands. This new MGC has a module composed of a high-resolution interchangeable collimator and a CsI(Na) scintillating crystal. It has dimensions of around 15 cm x 8 cm x 9 cm and weighs 1 kg. The intraoperative assay of PTH (ioPTH) was used to confirm the complete resection of pathological tissue. All cases were operated on successfully by a MIP. The ioPTH confirmed the excision of all pathological tissues. The MGC proved its usefulness in all patients, even in a difficult case in which the first attempt with the gamma probe failed. In all cases it offered real-time accurate intraoperative images. The hand-held MGC is a useful instrument in MIP for PHPT. It may be used to complement the standard tools used to date, or may even replace them, at least in selected cases of single adenomas. (orig.)

  13. High-speed real-time single-pixel microscopy based on Fourier sampling

    CERN Document Server

    Guo, Qiang; Wang, Yuxi; Guo, Yong; Liu, Peng; Zhu, Xiurui; Cheng, Zheng; Yu, Zhenming; Chen, Minghua; Yang, Sigang; Xie, Shizhong

    2016-01-01

    Single-pixel cameras based on the concepts of compressed sensing (CS) leverage the inherent structure of images to retrieve them with far fewer measurements and operate efficiently over a significantly broader spectral range than conventional silicon-based cameras. Recently, photonic time-stretch (PTS) technique facilitates the emergence of high-speed single-pixel cameras. A significant breakthrough in imaging speed of single-pixel cameras enables observation of fast dynamic phenomena. However, according to CS theory, image reconstruction is an iterative process that consumes enormous amounts of computational time and cannot be performed in real time. To address this challenge, we propose a novel single-pixel imaging technique that can produce high-quality images through rapid acquisition of their effective spatial Fourier spectrum. We employ phase-shifting sinusoidal structured illumination instead of random illumination for spectrum acquisition and apply inverse Fourier transform to the obtained spectrum fo...

  14. Image Mining in Remote Sensing for Coastal Wetlands Mapping: from Pixel Based to Object Based Approach

    Science.gov (United States)

    Farda, N. M.; Danoedoro, P.; Hartono; Harjoko, A.

    2016-11-01

    The availably of remote sensing image data is numerous now, and with a large amount of data it makes “knowledge gap” in extraction of selected information, especially coastal wetlands. Coastal wetlands provide ecosystem services essential to people and the environment. The aim of this research is to extract coastal wetlands information from satellite data using pixel based and object based image mining approach. Landsat MSS, Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 OLI images located in Segara Anakan lagoon are selected to represent data at various multi temporal images. The input for image mining are visible and near infrared bands, PCA band, invers PCA bands, mean shift segmentation bands, bare soil index, vegetation index, wetness index, elevation from SRTM and ASTER GDEM, and GLCM (Harralick) or variability texture. There is three methods were applied to extract coastal wetlands using image mining: pixel based - Decision Tree C4.5, pixel based - Back Propagation Neural Network, and object based - Mean Shift segmentation and Decision Tree C4.5. The results show that remote sensing image mining can be used to map coastal wetlands ecosystem. Decision Tree C4.5 can be mapped with highest accuracy (0.75 overall kappa). The availability of remote sensing image mining for mapping coastal wetlands is very important to provide better understanding about their spatiotemporal coastal wetlands dynamics distribution.

  15. Development of a phantom and assessment of (141)Ce as a surrogate radionuclide for flood field uniformity testing of gamma cameras.

    Science.gov (United States)

    Saxena, Sanjay Kumar; Kumar, Yogendra; Malpani, Basant; Rakshit, Sutapa; Dash, Ashutosh

    2016-06-01

    This paper describes an indigenous method for development and deployment of rechargeable liquid filled phantom with newly proposed radionuclide (141)Ce for determination of extrinsic uniformity of gamma cameras. Details about design of phantom, neutron irradiation of cerium targets, chemical processing of (141)Ce, charging of phantom with (141)Ce solution and their performance evaluation are presented. Suitability of (141)Ce in quality assurance of gamma cameras used in in-vivo diagnostic imaging procedures has been amply demonstrated.

  16. Single-pixel 3D imaging with time-based depth resolution

    CERN Document Server

    Sun, Ming-Jie; Gibson, Graham M; Sun, Baoqing; Radwell, Neal; Lamb, Robert; Padgett, Miles J

    2016-01-01

    Time-of-flight three dimensional imaging is an important tool for many applications, such as object recognition and remote sensing. Unlike conventional imaging approach using pixelated detector array, single-pixel imaging based on projected patterns, such as Hadamard patterns, utilises an alternative strategy to acquire information with sampling basis. Here we show a modified single-pixel camera using a pulsed illumination source and a high-speed photodiode, capable of reconstructing 128x128 pixel resolution 3D scenes to an accuracy of ~3 mm at a range of ~5 m. Furthermore, we demonstrate continuous real-time 3D video with a frame-rate up to 12 Hz. The simplicity of the system hardware could enable low-cost 3D imaging devices for precision ranging at wavelengths beyond the visible spectrum.

  17. Study of FPGA and GPU based pixel calibration for ATLAS IBL

    CERN Document Server

    Dopke, J; The ATLAS collaboration; Flick, T; Gabrielli, A; Grosse-Knetter, J; Krieger, N; Kugel, A; Polini, A; Schroer, N

    2010-01-01

    The insertable B-layer (IBL) is a new stage of the ATLAS pixel detector to be installed around 2014. 12 million pixel are attached to new FE-I4 readout ASICs, each controlling 26680 pixel. Compared to the existing FE-I3 based detector the new system features higher readout speed of 160Mbit/s per ASIC and simplified control. For calibration defined charges are applied to all pixels and the resulting time-over-threshold values are evaluated. In the present system multiple sets of two custom VME cards which employ a combination of FPGA and DSP technology are used for I/O interfacing, formatting and processing. The execution time of 51s to perform a threshold scan on a FE-I3 module of 46080 pixel is composed of 8s control, 29s transfer, 7.5s histogramming and 7s analysis. Extrapolating to FE-I4 the times per module of 53760 pixels are 12ms, 5.8s, 9.4s and 8.3s, a total of 23.5s. We present a proposal for a novel approach to the dominant tasks for FE-I4: histogramming and ananlysis. An FPGA-based histogramming uni...

  18. Design optimization of Pixel Structure for α-Si based uncooled Infrared detector

    Directory of Open Access Journals (Sweden)

    Sudha Gupta

    2013-12-01

    Full Text Available In this paper authors present the design and simulation results achieved for pixel structure of amorphous Si (α-Si based bolometer array. Most uncooled IR detectors in the world are based on VOx material. But this is not a standard material in IC technology and has many inherent disadvantages. The α-Si, an alternative material with high TCR is becoming as popular. However, large TCR values, in this material are achieved only in films of high resistivity. To achieve TCR value more than 2.5%/K, α-Si film resistivity is ~ 80 ohms-cm. This gives rise to very large pixel resistance of the order of 100 Mega ohms depending upon the design of the leg structure. This high pixel resistance causes very large noise and hence lower sensitivity. If leg width or membrane thickness is increased in order to reduce the pixel resistance, then this results in higher thermal conductance which also decreases sensitivity. To overcome this problem, pixel structure is so designed that within a pixel, only part of the electrical conduction is through α-Si and rest is through metal. Simulation using Coventorware software has been done to optimize pixel resistance as well as thermal conductance through legs so that maximum sensitivity could be obtained. Optimization is also carried out in order to reduce sensitivity of pixel resistance to variation in material resistivity.Defence Science Journal, 2013, 63(6, pp.581-588, DOI:http://dx.doi.org/10.14429/dsj.63.5758

  19. News in nuclear cardiology: A gamma camera with semiconductors dedicated to cardiac imaging;Nouveautes en cardiologie nucleaire: une gamma camera a semi-conducteurs dediee a l'imagerie cardiaque

    Energy Technology Data Exchange (ETDEWEB)

    Godbert, Y.; Bullier, E.; Riviere, A.L.; Laffon, E.; Guyot, M.; Bordenave, L.; Barat, J.L. [CHU de Bordeaux, Service de medecine nucleaire, hopital du Haut-Leveque, 33 - Pessac (France)

    2010-03-15

    During the last few years, cardiac imaging made important breakthroughs thanks to the development of various techniques allowing the risk stratification of patients with coronary artery disease. The well-established single photon emission computed tomography (SPECT) as a myocardial imaging technique made an important progress with the recent improvement of high-speed volume acquisition, using dedicated semi-conductor gamma camera. These cameras bring significant improvement to the image quality and the image acquisition time, which is now seven times lower. New type of artefacts is expected because of the geometry of detection, thus studies are still needed to assess the exact performance of this revolutionary technology. (authors)

  20. A pixellated γ-camera based on CdTe detectors clinical interests and performances

    Science.gov (United States)

    Chambron, J.; Arntz, Y.; Eclancher, B.; Scheiber, Ch; Siffert, P.; Hage Hali, M.; Regal, R.; Kazandjian, A.; Prat, V.; Thomas, S.; Warren, S.; Matz, R.; Jahnke, A.; Karman, M.; Pszota, A.; Nemeth, L.

    2000-07-01

    A mobile gamma camera dedicated to nuclear cardiology, based on a 15 cm×15 cm detection matrix of 2304 CdTe detector elements, 2.83 mm×2.83 mm×2 mm, has been developed with a European Community support to academic and industrial research centres. The intrinsic properties of the semiconductor crystals - low-ionisation energy, high-energy resolution, high attenuation coefficient - are potentially attractive to improve the γ-camera performances. But their use as γ detectors for medical imaging at high resolution requires production of high-grade materials and large quantities of sophisticated read-out electronics. The decision was taken to use CdTe rather than CdZnTe, because the manufacturer (Eurorad, France) has a large experience for producing high-grade materials, with a good homogeneity and stability and whose transport properties, characterised by the mobility-lifetime product, are at least 5 times greater than that of CdZnTe. The detector matrix is divided in 9 square units, each unit is composed of 256 detectors shared in 16 modules. Each module consists in a thin ceramic plate holding a line of 16 detectors, in four groups of four for an easy replacement, and holding a special 16 channels integrated circuit designed by CLRC (UK). A detection and acquisition logic based on a DSP card and a PC has been programmed by Eurorad for spectral and counting acquisition modes. Collimators LEAP and LEHR from commercial design, mobile gantry and clinical software were provided by Siemens (Germany). The γ-camera head housing, its general mounting and the electric connections were performed by Phase Laboratory (CNRS, France). The compactness of the γ-camera head, thin detectors matrix, electronic readout and collimator, facilitates the detection of close γ sources with the advantage of a high spatial resolution. Such an equipment is intended to bedside explorations. There is a growing clinical requirement in nuclear cardiology to early assess the extent of an

  1. Method of conjugate gamma camera image to determine tumor uptake in other thyroid treatments with I-131; Metodo de la imagen conjugada en Gammacamara para determinar la captacion en resto tumoral tiroideo en tratamientos con I-131

    Energy Technology Data Exchange (ETDEWEB)

    Barquero, R.; Sainz, A.; Tortosa, R.; Mari, A.

    2011-07-01

    The efficacy of ablation of thyroid remnants with 1-131 in the treatment of CDT depends on the activity captured in these remains, the optimal method for quantifying this activity is based on the gamma camera imaging with in the course of treatment. However, due to saturation of the image with high activities and time-cost optimization of machine, not usually get those images, except in a post-treatment scan. In our service MN tracking each patient is between 6 and 9 after administration. A method of quantification of the activity captured in other thyroid screening using this image.

  2. 3D position of radiation sources using an automated gamma camera and ML algorithm with energy-dependent response functions

    Science.gov (United States)

    Lee, Wonho; Wehe, David

    2004-09-01

    Portable γ-ray imaging systems operating from 100keV to 3MeV are used in nuclear medicine, astrophysics and industrial applications. 2D images of γ-rays are common in many fields using radiation-detection systems (Appl. Opt. 17 (3) (1978) 337; IEEE Trans. Nucl. Sci. Ns- 31 (1984) 771; IEEE Trans. Nucl. Sci. NS- 44 (3) (1997) 911). In this work, the 3D position of a radiation source is determined by a portable gamma-ray imaging system. 2D gamma-ray images were obtained from different positions of the gamma camera and the third dimension, the distance between the detector and the radiation source, was calculated using triangulation. The imaging system consists of a 4×4 array of CsI(Tl) detectors coupled to photodiode detectors that are mounted on an automated table which can precisely position the angular axis of the camera. Lead shields the detector array from the background radiation. Additionally, a CCD camera is attached to the top of the gamma camera and provides coincident 2D visual information. The inferred distances from the center of the two measurement points and a radiation source had less than a 3% error within a range of 3m. The radiation image from the gamma camera and the visual image from CCD camera are superimposed into one combined image using a maximum-likelihood (ML) algorithm to make the image more precise. The response functions for the ML algorithm depend on the energy of incident radiation, and are obtained from both experiments and simulations. The energy-dependent response functions are shown to yield better imaging performance compared with the fixed energy response function commonly used previously.

  3. Toward VIP-PIX: A Low Noise Readout ASIC for Pixelated CdTe Gamma-Ray Detectors for Use in the Next Generation of PET Scanners.

    Science.gov (United States)

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Puigdengoles, Carles; Lorenzo, Gianluca De; Martínez, Ricardo

    2013-08-01

    VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-triggered pixel which will be connected to a global time-to-digital converter (TDC) with 1 ns resolution will provide the event's time stamp. The analog part of the readout chain and the ADC have been fabricated with TSMC 0.25 μm mixed-signal CMOS technology and characterized with an external test pulse. The power consumption of these parts is 200 μW from a 2.5 V supply. It offers 4 switchable gains from ±10 mV/fC to ±40 mV/fC and an input charge dynamic range of up to ±70 fC for the minimum gain for both polarities. Based on noise measurements, the expected equivalent noise charge (ENC) is 65 e(-) RMS at room temperature.

  4. Skin Pixel Segmentation Using Learning Based Classification: Analysis and Performance Comparison

    Directory of Open Access Journals (Sweden)

    Rajandeep Sohal

    2014-05-01

    Full Text Available Skin detection or segmentation is employed in many tasks related to the detection and tracking of humans and human-body parts. The goal of skin pixel detection is locate the pixels of the skins and discard other non-related pixels from regions of the image. Skin area detection has been focus research area in human-computer interactions. Most of the research done in the fields of skin detection has been trained and tested on human images. The approach of this research is to make a comparative analysis of learning classification algorithms to identify the better classifier model for skin pixel detection. Our adopted procedure is based on skin segmentation and human face features which are so called knowledge based approach for skin pixel segmentation. Based on the feature selection of the classified, we found the good detection rate by using the various classification algorithms. We have got the detection rate of above 95.79% in case of J48 algorithm and 95.04% detection rate in case of SMO algorithm. The experiment result shows that, the algorithm gives hopeful results. At last, we concluded this paper and proposed future work.

  5. Category Decomposition Method Based on Matched Filter for Un-Mixing of Mixed Pixels Acquired with Spaceborne Based Hyperspectral Radiometers

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-06-01

    Full Text Available Category decomposition method based on matched filter for un-mixing of mixed pixels: mixels which are acquired with spaceborne based hyperspectral radiometers is proposed. Through simulation studies with simulated mixed pixels which are created with spectral reflectance data derived from USGS spectral library as well as actual airborne based hyperspectral radiometer imagery data, it is found that the proposed method works well with acceptable decomposition accuracy.

  6. The Analytic Hierarchy Method-Based Algorithm for Restoring Broken Pixels on the Noisy Images

    Directory of Open Access Journals (Sweden)

    S. V. Belim

    2014-01-01

    Full Text Available This article presents an algorithm for restoring broken pixels, which can appear in graphic files with statistical gaps. The suggested algorithm is based on the method of hierarchical analysis of the decision support theory. The choice of the broken pixel color depends on the nearest neighbors and their next neighbors. Three parameters inherent in each nearest neighbor are analysed. Firstly, it is the number of neighbors, which have the same color as the given nearest neighbor. Secondly, it is a deviation of the given pixel from the average value of its neighbors. Thirdly, it is a difference between the pixels being on the opposite sides of the broken pixel. Based on these three criteria, for each nearest neighbor of the broken pixel, a weight coefficient is defined. A hierarchical two-level tree for making decision is constructed. As a color of the broken pixel, its neighbor color with the maximum weight is chosen.A computer experiment to determine the effectiveness of the proposed method is conducted. The effectiveness of the proposed method was determined by comparing the similarity degree of the broken and restored images to the source image. To compare images Minkowski metric was used. To conduct experiments photographic and artificial images were used. The paper investigates a dependence of the proposed algorithm efficiency on the broken image amount. It was found out that the proposed algorithm has the advantage over the known algorithms for restoring broken pixels near the sharp edges. An image restored by our method has more sharply defined edges as compared to what the smoothing filters provide. The proposed method can be iteratively applied. As the experiments have shown, the first five iterations provide image enhancement.The proposed method together with the algorithms for detecting the broken pixels can be used to design filters of noisy images. The method efficiency enhancement can be achieved in case of taking into account the

  7. Compact SPAD-Based Pixel Architectures for Time-Resolved Image Sensors.

    Science.gov (United States)

    Perenzoni, Matteo; Pancheri, Lucio; Stoppa, David

    2016-05-23

    This paper reviews the state of the art of single-photon avalanche diode (SPAD) image sensors for time-resolved imaging. The focus of the paper is on pixel architectures featuring small pixel size (20%) as a key enabling technology for the successful implementation of high spatial resolution SPAD-based image sensors. A summary of the main CMOS SPAD implementations, their characteristics and integration challenges, is provided from the perspective of targeting large pixel arrays, where one of the key drivers is the spatial uniformity. The main analog techniques aimed at time-gated photon counting and photon timestamping suitable for compact and low-power pixels are critically discussed. The main features of these solutions are the adoption of analog counting techniques and time-to-analog conversion, in NMOS-only pixels. Reliable quantum-limited single-photon counting, self-referenced analog-to-digital conversion, time gating down to 0.75 ns and timestamping with 368 ps jitter are achieved.

  8. Compact SPAD-Based Pixel Architectures for Time-Resolved Image Sensors

    Directory of Open Access Journals (Sweden)

    Matteo Perenzoni

    2016-05-01

    Full Text Available This paper reviews the state of the art of single-photon avalanche diode (SPAD image sensors for time-resolved imaging. The focus of the paper is on pixel architectures featuring small pixel size (<25 μm and high fill factor (>20% as a key enabling technology for the successful implementation of high spatial resolution SPAD-based image sensors. A summary of the main CMOS SPAD implementations, their characteristics and integration challenges, is provided from the perspective of targeting large pixel arrays, where one of the key drivers is the spatial uniformity. The main analog techniques aimed at time-gated photon counting and photon timestamping suitable for compact and low-power pixels are critically discussed. The main features of these solutions are the adoption of analog counting techniques and time-to-analog conversion, in NMOS-only pixels. Reliable quantum-limited single-photon counting, self-referenced analog-to-digital conversion, time gating down to 0.75 ns and timestamping with 368 ps jitter are achieved.

  9. Optoelectronic multiplexer for digital data processing based on lipid crystal pixels and optical fiber elements

    Science.gov (United States)

    Pérez, I.; Pena, J. M. S.; Torres, J. C.; Manzanares, R.; Marcos, C.; Vázquez, C.

    2007-06-01

    In this work, we present an optoelectronic digital multiplexer 4:1 based on a multipixel nematic liquid crystal cell. This device uses two optical control signals to select one among four possible optical data inputs. These data signals are generated by four red LEDs, which are guided through plastic optical fiber towards liquid crystal pixels. For our purpose, only four pixels of the cell will be used to modulate the optical signal across them. Each pixel will be addressed by a square waveform coming from the conditioning circuit managed by a microcontroller system. The electronic control allows the multiplexer to work as as simple two input logical gates such as AND, NAND, OR, NOR, XOR and XNOR. The operation time of the device is limited by the response time of LC cell that is in the millisecond range.

  10. Steganalysis for LSB Matching Based on the Dependences Between Neighboring Pixels

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2012-10-01

    Full Text Available It is hard to detect LSB matching steganography, especially in low embedding rate. However there are still some chances to attack it since the data embedding alters the dependences between neighboring pixels.  Based on this fact, this paper proposes a novel steganalysis method by modeling the dependences. The neighboring pixels are divided into three groups: horizontal, vertical, and diagonal.  Then, the prediction errors of the central pixel are calculated by each group respectively. Finally, the empirical probability matrices among these prediction errors are computed and used as features for steganalysis. Experimental results show the proposed method has better performance than SPAM scheme, which currently is the most sensitive detector for LSB Matching. Furthermore, combined with the SPAM features, the method achieves the best accuracy.

  11. A Leakage Current-based Measurement of the Radiation Damage in the ATLAS Pixel Detector

    CERN Document Server

    Gorelov, Igor; The ATLAS collaboration

    2015-01-01

    A measurement has been made of the radiation damage incurred by the ATLAS Pixel Detector barrel silicon modules from the beginning of operations through the end of 2012. This translates to hadronic fluence received over the full period of operation at energies up to and including 8 TeV. The measurement is based on a per-module measurement of the silicon sensor leakage current. The results are presented as a function of integrated luminosity and compared to predictions by the Hamburg Model. This information can be used to predict limits on the lifetime of the Pixel Detector due to current, for various operating scenarios.

  12. Design and implementation of a quality assurance program for gamma cameras; Diseno e implementacion de un programa de aseguramiento de calidad para camaras gamma

    Energy Technology Data Exchange (ETDEWEB)

    Montoya M, A.; Rodriguez L, A. [Instituto Nacional de Cancerologia, Departamento de Medicina Nuclear, Av. San Fernando No. 22, Col. Seccion XVI, 14080 Mexico D. F. (Mexico); Trujillo Z, F. E., E-mail: montoya-moreno@hotmail.co [Hospital Regional de Alta Especialidad de Oaxaca, Area de Fisica Medica, Aldama s/n, Paraje El Tule, 71256 San Bartolo Coyotepec, Oaxaca (Mexico)

    2010-09-15

    In nuclear medicine more than 90% of the carried out procedures are diagnostic. To assure an appropriate diagnostic quality of the images and the doses optimization received by the patients originated in the radioactive material, it is indispensable the periodic surveillance of the operation and performance of the equipment s by means of quality assurance tests. This work presents a proposal of a quality assurance program for gamma cameras based on recommendations of the IAEA, the American Association of Medical Physics and the National Electrical Manufacturers Association. Some tests of the program were applied to an e.cam gamma camera (Siemens) of the Nuclear Medicine Department of the National Institute of Cancer. The intrinsic and extrinsic uniformity, the intrinsic spatial resolution and the extrinsic sensibility were verified. For intrinsic uniformity the average daily values of the integral uniformity and differential uniformity in the useful vision field were 2.61% and 1.58% respectively, the average monthly values of intrinsic uniformity for the integral and differential uniformity in the useful vision field were 4.10% and 1.66% respectively. The used acceptance criterions were respectively of 3.74% and 2.74%. The average values of extrinsic uniformity for the useful vision field were of 7.65% (intrinsic uniformity) and 2.69% (extrinsic uniformity), in this case the acceptance criterion is a value of 6.00%. The average value of intrinsic spatial resolution went 4.67 mm superior to 4.4. mm that is the acceptance limit. Finally, maximum variations of 1.8% were observed (minors than 2% that is the acceptance criterion) for the extrinsic sensibility measured in different regions of the detector. Significant variations of extrinsic sensibility were not observed among the monthly lectures. Of the realized measurements was concluded that the system requires of a maintenance service by part of the manufacturer, which one carries out later on to this work. The

  13. Pixel-based skin segmentation in psoriasis images.

    Science.gov (United States)

    George, Y; Aldeen, M; Garnavi, R

    2016-08-01

    In this paper, we present a detailed comparison study of skin segmentation methods for psoriasis images. Different techniques are modified and then applied to a set of psoriasis images acquired from the Royal Melbourne Hospital, Melbourne, Australia, with aim of finding the best technique suited for application to psoriasis images. We investigate the effect of different colour transformations on skin detection performance. In this respect, explicit skin thresholding is evaluated with three different decision boundaries (CbCr, HS and rgHSV). Histogram-based Bayesian classifier is applied to extract skin probability maps (SPMs) for different colour channels. This is then followed by using different approaches to find a binary skin map (SM) image from the SPMs. The approaches used include binary decision tree (DT) and Otsu's thresholding. Finally, a set of morphological operations are implemented to refine the resulted SM image. The paper provides detailed analysis and comparison of the performance of the Bayesian classifier in five different colour spaces (YCbCr, HSV, RGB, XYZ and CIELab). The results show that histogram-based Bayesian classifier is more effective than explicit thresholding, when applied to psoriasis images. It is also found that decision boundary CbCr outperforms HS and rgHSV. Another finding is that the SPMs of Cb, Cr, H and B-CIELab colour bands yield the best SMs for psoriasis images. In this study, we used a set of 100 psoriasis images for training and testing the presented methods. True Positive (TP) and True Negative (TN) are used as statistical evaluation measures.

  14. Low noise pixel detectors based on gated geiger mode avalanche photodiodes

    OpenAIRE

    Vilella Figueras, Eva; Comerma Montells, Albert; Alonso Casanovas, Oscar; Diéguez Barrientos, Àngel

    2011-01-01

    The gated operation is proposed as an effective method to reduce the noise in pixel detectors based on Geiger mode avalanche photodiodes. A prototype with the sensor and the front-end electronics monolithically integrated has been fabricated with a conventional HV-CMOS process. Experimental results demonstrate the increase of the dynamic range of the sensor by applying this technique.

  15. Development of pixelated scintillator-based compact radio-TLC

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Sang June; Kim, Kyeong Min; Kim, Jong Guk [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2016-05-15

    The radio-TLC system generally shows as a graph of counting gamma radioactivity, emitting by radiopharmaceutical including a specific radioisotope. it makes guarantee quantitative accuracy and reproducibility for chemically stability and change of a targeting radiopharmaceutical. In present the radio-TLC produced by a few companies use a gas-filled proportional counter with high cost, and it has limitations of both gas diffusion and ion density. Recently, Ce:GAGG has been developed and presented as promising scintillators for PET and SPECT due to high density, high light yield (- 46,000-51,000 photon/MeV), and fast decay time. We have adapted GAGG scintillation crystal array to radio-TLC detector. We developed the GAGG crystal array based radio-TLC RT-102. The RT-102 has several advantages such as the compact size, the no-gas usage, and the lower cost in comparison with commercial radio-TLC scanner. In order to verify the performance of RT-102, we compared RT-102 with AR-2000. We scanned and compared Tc-99m and F-18 solution spotted samples in the same conditions. The ROI counts ratio and position detecting performances of RT-102 are approximately same with AR-2000. The results indicate the RT-102 has enough resolution and sensitivity to be used in the measurement of radiochemical purity test in radio-TLC devices.

  16. Localization of the placenta in the 3 trimester of gestation with the use of a gamma-camera and radioactive sup(113m)In indium isotope

    Energy Technology Data Exchange (ETDEWEB)

    Brudnik, A.; Chromy, G.; Ulfik, A.; Bielawski, J.; Wasylewski, A. (Slaska Akademia Medyczna, Katowice (Poland))

    1980-01-01

    In 56 women, treated because of uterine bleedings in the 3 trimester of gestation the localization of the placenta was looked for with use of a gamma camera (Toshiba Co.) and indium radioisotope 113-In. The methodic procedures were elaborated for the application of the gamma-camera and the utilization of radioactive marker /sup 125/Sb in the anatomic reference areas. Full conformity of results with findings at cesarean section was met. Isotope placentography with the application of gamma camera gives a high percentage of adequate diagnoses, least dose of exposition, uncomplicated procedures. The negative diagnosis in suspected cases of placenta previa permitted to decrease the time of hospital stay in a number of cases observed because of uterine bleedings in the 3 trimester of pregnancy.

  17. Tumor dosimetry for I-131 trastuzumab therapy in a Her2+ NCI N87 xenograft mouse model using the Siemens SYMBIA E gamma camera with a pinhole collimator

    Science.gov (United States)

    Lee, Young Sub; Kim, Jin Su; Deuk Cho, Kyung; Kang, Joo Hyun; Moo Lim, Sang

    2015-07-01

    We performed imaging and therapy using I-131 trastuzumab and a pinhole collimator attached to a conventional gamma camera for human use in a mouse model. The conventional clinical gamma camera with a 2-mm radius-sized pinhole collimator was used for monitoring the animal model after administration of I-131 trastuzumab The highest and lowest radiation-received organs were osteogenic cells (0.349 mSv/MBq) and skin (0.137 mSv/MBq), respectively. The mean coefficients of variation (%CV) of the effective dose equivalent and effective dose were 0.091 and 0.093 mSv/MBq respectively. We showed the feasibility of the pinholeattached conventional gamma camera for human use for the assessment of dosimetry. Mouse dosimetry and prediction of human dosimetry could be used to provide data for the safety and efficacy of newly developed therapeutic schemes.

  18. Autonomous Sub-Pixel Satellite Track Endpoint Determination for Space Based Images

    Energy Technology Data Exchange (ETDEWEB)

    Simms, L M

    2011-03-07

    An algorithm for determining satellite track endpoints with sub-pixel resolution in spaced-based images is presented. The algorithm allows for significant curvature in the imaged track due to rotation of the spacecraft capturing the image. The motivation behind the subpixel endpoint determination is first presented, followed by a description of the methodology used. Results from running the algorithm on real ground-based and simulated spaced-based images are shown to highlight its effectiveness.

  19. Adaptive Multi-Objective Sub-Pixel Mapping Framework Based on Memetic Algorithm for Hyperspectral Remote Sensing Imagery

    Science.gov (United States)

    Zhong, Y.; Zhang, L.

    2012-07-01

    Sub-pixel mapping technique can specify the location of each class within the pixels based on the assumption of spatial dependence. Traditional sub-pixel mapping algorithms only consider the spatial dependence at the pixel level. The spatial dependence of each sub-pixel is ignored and sub-pixel spatial relation is lost. In this paper, a novel multi-objective sub-pixel mapping framework based on memetic algorithm, namely MSMF, is proposed. In MSMF, the sub-pixel mapping is transformed to a multi-objective optimization problem, which maximizing the spatial dependence index (SDI) and Moran's I, synchronously. Memetic algorithm is utilized to solve the multi-objective problem, which combines global search strategies with local search heuristics. In this framework, the sub-pixel mapping problem can be solved using different evolutionary algorithms and local algorithms. In this paper, memetic algorithm based on clonal selection algorithm (CSA) and random swapping as an example is designed and applied simultaneously in the proposed MSMF. In MSMF, CSA inherits the biologic properties of human immune systems, i.e. clone, mutation, memory, to search the possible sub-pixel mapping solution in the global space. After the exploration based on CSA, the local search based on random swapping is employed to dynamically decide which neighbourhood should be selected to stress exploitation in each generation. In addition, a solution set is used in MSMF to hold and update the obtained non-dominated solutions for multi-objective problem. Experimental results demonstrate that the proposed approach outperform traditional sub-pixel mapping algorithms, and hence provide an effective option for sub-pixel mapping of hyperspectral remote sensing imagery.

  20. Data concentrator with FPGA-based track reconstruction for the Belle II DEPFET pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Schnell, Michael; Dingfelder, Jochen; Marinas, Carlos [Physikalisches Institut, Universitaet Bonn (Germany)

    2013-07-01

    The innermost two layers of the Belle II vertex detector at the KEK facility in Tsukuba, Japan, will be covered by high-granularity DEPFET pixel sensors. The large number of pixels leads to a high data rate of around 60 Gbps, which has to be significantly reduced by the Data Acquisition System. For the data reduction the hit information of the surrounding Silicon strip Vertex Detector (SVD) is utilized to define so-called Regions of Interest (ROI). Only hit information of the pixels located inside these ROIs are saved. The ROIs for the Pixel Detector (PXD) are computed by reconstructing track segments from SVD data and back extrapolation to the PXD. A data reduction of up to a factor of 10 is intended to be achieved by this design. All the necessary processing stages, the receiving and multiplexing of the data from the SVD on 48 optical fibers, the track reconstruction and the definition of the ROIs, will be performed by the Data Concentrator. The planned hardware design is based on a distributed set of Advanced Mezzanine Cards (AMC) each equipped with a Field Programmable Gate Array (FPGA) chip and 4 optical transceivers. In this talk, the hardware and the FPGA-based tracking algorithm is introduced with some preliminary simulation results. In addition, the acquisition and pre-processing of the SVD data are discussed. The presentation concludes with an outlook on a distributed tracking design.

  1. An enhanced high-resolution EMCCD-based gamma camera using SiPM side detection

    NARCIS (Netherlands)

    Heemskerk, J.W.T.; Korevaar, M.A.N.; Huizenga, J.; Kreuger, R.; Schaart, D.R.; Goorden, M.C.; Beekman, F.J.

    2010-01-01

    To improve multi-pinhole single photon emission computed tomography (SPECT) devices we are developing a high-resolution gamma detector consisting of a 3-mm-thick scintillation crystal that converts gamma photons to light, on top of an optically coupled high-resolution, high-sensitivity light sensor

  2. An enhanced high-resolution EMCCD-based gamma camera using SiPM side detection

    NARCIS (Netherlands)

    Heemskerk, J.W.T.; Korevaar, M.A.N.; Huizenga, J.; Kreuger, R.; Schaart, D.R.; Goorden, M.C.; Beekman, F.J.

    2010-01-01

    To improve multi-pinhole single photon emission computed tomography (SPECT) devices we are developing a high-resolution gamma detector consisting of a 3-mm-thick scintillation crystal that converts gamma photons to light, on top of an optically coupled high-resolution, high-sensitivity light sensor

  3. The HURRA filter: An easy method to eliminate collimator artifacts in high-energy gamma camera images.

    Science.gov (United States)

    Perez-Garcia, H; Barquero, R

    The correct determination and delineation of tumor/organ size is crucial in 2-D imaging in (131)I therapy. These images are usually obtained using a system composed of a Gamma camera and high-energy collimator, although the system can produce artifacts in the image. This article analyses these artifacts and describes a correction filter that can eliminate those collimator artifacts. Using free software, ImageJ, a central profile in the image is obtained and analyzed. Two components can be seen in the fluctuation of the profile: one associated with the stochastic nature of the radiation, plus electronic noise and the other periodically across the position in space due to the collimator. These frequencies are analytically obtained and compared with the frequencies in the Fourier transform of the profile. A specially developed filter removes the artifacts in the 2D Fourier transform of the DICOM image. This filter is tested using a 15-cm-diameter Petri dish with (131)I radioactive water (big object size) image, a (131)I clinical pill (small object size) image, and an image of the remainder of the lesion of two patients treated with 3.7GBq (100mCi), and 4.44GBq (120mCi) of (131)I, respectively, after thyroidectomy. The artifact is due to the hexagonal periodic structure of the collimator. The use of the filter on large-sized images reduces the fluctuation by 5.8-3.5%. In small-sized images, the FWHM can be determined in the filtered image, while this is impossible in the unfiltered image. The definition of tumor boundary and the visualization of the activity distribution inside patient lesions improve drastically when the filter is applied to the corresponding images obtained with HE gamma camera. The HURRA filter removes the artifact of high-energy collimator artifacts in planar images obtained with a Gamma camera without reducing the image resolution. It can be applied in any study of patient quantification because the number of counts remains invariant. The filter

  4. Rapid radiotracer washout from the heart: effect on image quality in SPECT performed with a single-headed gamma camera system.

    Science.gov (United States)

    O'Connor, M K; Cho, D S

    1992-06-01

    Technetium-99m-teboroxime demonstrates high extraction and rapid washout from the myocardium. To evaluate the feasibility of performing SPECT with this agent using a single-headed gamma camera system, a series of phantom studies were performed that simulated varying degrees of washout from normal and "ischemic" regions of the myocardium. In the absence of ischemic regions, short axis profiles were relatively unaffected by washout of less than 50% of activity over the duration of a SPECT acquisition. However, significant corruption of the SPECT data was observed when large (greater than a factor of 2) differences existed in the washout of activity from normal and "ischemic" myocardium. This corruption was observed with 30%-40% washout of activity from normal regions of the heart. Based on published washout rates, these results indicate that clinical studies with 99mTc-teboroxime may need to be completed within 2-4 min to order to prevent degradation of image quality due to differential washout effects.

  5. DEM-Based SAR Pixel Area Estimation For Enhanced Geocoding Refinement And Radiometric Normalization

    Science.gov (United States)

    Frey, Othmar; Santoro, Maurizio; Werner, Charles L.; Wegmuller, Urs

    2012-01-01

    Precise terrain-corrected georeferencing of SAR images and derived products in range-Doppler coordinates is important with respect to several aspects, such as data interpretation, combination with other geodata products, and transformation of, e.g., terrain heights into SAR geometry as used in DInSAR applications. For georeferencing a look-up table is calculated and refined based on a coregistration of the actual SAR image to a simulated SAR image. The impact of using two different implementations of such a simulator of topography-induced radar brightness, an approach based on angular relationships and a pixel-area based method are discussed in this paper. It is found that the pixel-area-based method leads to considerable improvements with regard to the robustness of georeferencing and also with regard to radiometric normalization in layover- affected areas.

  6. An Improved Image Steganography Method Based on LSB Technique with Random Pixel Selection

    Directory of Open Access Journals (Sweden)

    Marwa M. Emam

    2016-03-01

    Full Text Available with the rapid advance in digital network, information technology, digital libraries, and particularly World Wide Web services, many kinds of information could be retrieved any time. Thus, the security issue has become one of the most significant problems for distributing new information. It is necessary to protect this information while passing over insecure channels. Steganography introduces a strongly approach to hide the secret data in an appropriate media carriers such as images, audio files, text files, and video files. In this paper, a new image steganography method based on spatial domain is proposed. According to the proposed method, the secret message is embedded randomly in the pixel location of the cover image using Pseudo Random Number Generator (PRNG of each pixel value of the cover image instead of embedding sequentially in the pixels of the cover image. This randomization is expected to increase the security of the system. The proposed method works with two layers (Blue and Green, as (2-1-2 layer, and the byte of the message will be embedded in three pixels only in this form (3-2-3. From the experimental results, it has found that the proposed method achieves a very high Maximum Hiding Capacity (MHC, and higher visual quality as indicated by the Peak Signal-to- Noise Ratio (PSNR.

  7. An RGB colour image steganography scheme using overlapping block-based pixel-value differencing.

    Science.gov (United States)

    Prasad, Shiv; Pal, Arup Kumar

    2017-04-01

    This paper presents a steganographic scheme based on the RGB colour cover image. The secret message bits are embedded into each colour pixel sequentially by the pixel-value differencing (PVD) technique. PVD basically works on two consecutive non-overlapping components; as a result, the straightforward conventional PVD technique is not applicable to embed the secret message bits into a colour pixel, since a colour pixel consists of three colour components, i.e. red, green and blue. Hence, in the proposed scheme, initially the three colour components are represented into two overlapping blocks like the combination of red and green colour components, while another one is the combination of green and blue colour components, respectively. Later, the PVD technique is employed on each block independently to embed the secret data. The two overlapping blocks are readjusted to attain the modified three colour components. The notion of overlapping blocks has improved the embedding capacity of the cover image. The scheme has been tested on a set of colour images and satisfactory results have been achieved in terms of embedding capacity and upholding the acceptable visual quality of the stego-image.

  8. Spatial and vertex resolution studies on the ATLAS Pixel Detector based on Combined Testbeam 2004 data

    CERN Document Server

    Reisinger, Ingo; Klingenberg, Reiner

    2006-01-01

    This diploma thesis deals with spatial and vertex resolution studies on the ATLAS Pixel detector based on real data taken during the Combined Testbeam period 2004 (17th May - 15th November). For the Combined Testbeam a barrel segment of the ATLAS Detector was build up and tested under real experimental conditions. Several data sets, being recorded during that time, are reconstructed by the ATLAS control framework called ATHENA. The input information for the reconstruction of the particle tracks through the Pixel Detector are the so-called spacepoints. Their uncertainty affects the resolution of the reconstructed particle tracks and thus, also the accuracy of the vertex reconstruction. Since traversing particles deposite their charge mostly (but not compellingly) within more than one pixel, all pixels corresponding to one hit have to be grouped together to a cluster. To compute the spacepoint from the cluster information two different strategies can be performed. The first one is a digital clustering, w...

  9. ORIS: the Oak Ridge Imaging System program listings. [Nuclear medicine imaging with rectilinear scanner and gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Bell, P. R.; Dougherty, J. M.

    1978-04-01

    The Oak Ridge Imaging System (ORIS) is a general purpose access, storage, processing and display system for nuclear medicine imaging with rectilinear scanner and gamma camera. This volume contains listings of the PDP-8/E version of ORIS Version 2. The system is designed to run under the Digital Equipment Corporation's OS/8 monitor in 16K or more words of core. System and image file mass storage is on RK8E disk; longer-time image file storage is provided on DECtape. Another version of this program exists for use with the RF08 disk, and a more limited version is for DECtape only. This latter version is intended for non-medical imaging.

  10. Results of optical Monte Carlo simulations of a compact {gamma} camera for the detection of sentinel lymph nodes

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, Dean; Truman, Andrew E-mail: atruman@bccancer.bc.ca; Kwok, Harry; Bergman, Alanah

    2001-07-11

    Breast cancer is most often treatable when detected in the early stages, before the primary disease spreads to sentinel lymph nodes in the axilla and supraclavicular region. A sentinel lymph node is the closest adjacent lymph node to receive lymphatic drainage from a primary breast tumour. It is from these nodes that cancer cells metastasise throughout the lymphatic system, spreading the disease. This work details the optical Monte Carlo modelling of an ultra compact, nuclear medicine {gamma} camera that will be used intra-operatively to detect malignant sentinel lymph nodes. This development will improve the identification and localisation of these sentinel nodes, thereby facilitating improved techniques for axillary lymph node dissection, and sentinel lymph node biopsy.

  11. Gamma camera energy windows for Tc-99m bone scintigraphy: effect of asymmetry on contrast resolution. Work in progress

    Energy Technology Data Exchange (ETDEWEB)

    Collier, B.D.; Palmer, D.W.; Knobel, J.; Isitman, A.T.; Hellman, R.S.; Zielonka, J.S.

    1984-05-01

    By raising the lower threshold of the Tc-99m energy window, rejection of scattered photons can be made more efficient. Unfortunately, with most gamma cameras significant nonuniformities are produced when the window is changed to an asymmetric setting. Recently introduced designs with gain stabilization of the photomultiplier tubes and improved energy correction maintain field uniformity even for an asymmetric window. To assess the impact of an asymmetric energy window on clinical images, 33 Tc-99m-MDP scintigrams of the lumbar spine were taken with symmetrical (126-154 keV) and asymmetric windows (135-154 keV). Bone:soft tissue ratios improved with the asymmetric window, and the resulting images were preferred by the physicians.

  12. Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera

    CERN Document Server

    Morozov, A; Marcos, J; Martins, R; Pereira, L; Solovov, V; Chepel, V

    2016-01-01

    Compact gamma cameras with a square-shaped monolithic scintillator crystal and an array of silicon photomultipliers (SiPMs) are actively being developed for applications in areas such as small animal imaging, cancer diagnostics and radiotracer guided surgery. Statistical methods of position reconstruction, which are potentially superior to the traditional centroid method, require accurate knowledge of the spatial response of each photomultiplier. Using both Monte Carlo simulations and experimental data obtained with a camera prototype, we show that the spatial response of all photomultipliers (light response functions) can be parameterized with axially symmetric functions obtained iteratively from flood field irradiation data. The study was performed with a camera prototype equipped with a 30 x 30 x 2 mm3 LYSO crystal and an 8 x 8 array of SiPMs for 140 keV gamma rays. The simulations demonstrate that the images, reconstructed with the maximum likelihood method using the response obtained with the iterative a...

  13. Imaging system for cardiac planar imaging using a dedicated dual-head gamma camera

    Science.gov (United States)

    Majewski, Stanislaw; Umeno, Marc M.

    2011-09-13

    A cardiac imaging system employing dual gamma imaging heads co-registered with one another to provide two dynamic simultaneous views of the heart sector of a patient torso. A first gamma imaging head is positioned in a first orientation with respect to the heart sector and a second gamma imaging head is positioned in a second orientation with respect to the heart sector. An adjustment arrangement is capable of adjusting the distance between the separate imaging heads and the angle between the heads. With the angle between the imaging heads set to 180 degrees and operating in a range of 140-159 keV and at a rate of up to 500kHz, the imaging heads are co-registered to produce simultaneous dynamic recording of two stereotactic views of the heart. The use of co-registered imaging heads maximizes the uniformity of detection sensitivity of blood flow in and around the heart over the whole heart volume and minimizes radiation absorption effects. A normalization/image fusion technique is implemented pixel-by-corresponding pixel to increase signal for any cardiac region viewed in two images obtained from the two opposed detector heads for the same time bin. The imaging system is capable of producing enhanced first pass studies, bloodpool studies including planar, gated and non-gated EKG studies, planar EKG perfusion studies, and planar hot spot imaging.

  14. Hyperspectral Data for Mangrove Species Mapping: A Comparison of Pixel-Based and Object-Based Approach

    Directory of Open Access Journals (Sweden)

    Muhammad Kamal

    2011-10-01

    Full Text Available Visual image interpretation and digital image classification have been used to map and monitor mangrove extent and composition for decades. The presence of a high-spatial resolution hyperspectral sensor can potentially improve our ability to differentiate mangrove species. However, little research has explored the use of pixel-based and object-based approaches on high-spatial hyperspectral datasets for this purpose. This study assessed the ability of CASI-2 data for mangrove species mapping using pixel-based and object-based approaches at the mouth of the Brisbane River area, southeast Queensland, Australia. Three mapping techniques used in this study: spectral angle mapper (SAM and linear spectral unmixing (LSU for the pixel-based approaches, and multi-scale segmentation for the object-based image analysis (OBIA. The endmembers for the pixel-based approach were collected based on existing vegetation community map. Nine targeted classes were mapped in the study area from each approach, including three mangrove species: Avicennia marina, Rhizophora stylosa, and Ceriops australis. The mapping results showed that SAM produced accurate class polygons with only few unclassified pixels (overall accuracy 69%, Kappa 0.57, the LSU resulted in a patchy polygon pattern with many unclassified pixels (overall accuracy 56%, Kappa 0.41, and the object-based mapping produced the most accurate results (overall accuracy 76%, Kappa 0.67. Our results demonstrated that the object-based approach, which combined a rule-based and nearest-neighbor classification method, was the best classifier to map mangrove species and its adjacent environments.

  15. Ultrafast nuclear myocardial perfusion imaging on a new gamma camera with semiconductor detector technique: first clinical validation

    Energy Technology Data Exchange (ETDEWEB)

    Buechel, Ronny R.; Herzog, Bernhard A.; Husmann, Lars; Burger, Irene A.; Pazhenkottil, Aju P.; Treyer, Valerie; Valenta, Ines; Schulthess, Patrick von; Nkoulou, Rene; Wyss, Christophe A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University of Zurich, Zurich Center for Integrative Human Physiology (ZIHP), Zurich (Switzerland)

    2010-04-15

    To assess the diagnostic performance of a novel ultrafast cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors for nuclear myocardial perfusion imaging (MPI). The study group comprised 75 consecutive patients (55 men, BMI range 19-45 kg/m{sup 2}) who underwent a 1-day {sup 99m}Tc-tetrofosmin adenosine-stress/rest imaging protocol. Scanning was performed first on a conventional dual-detector SPECT gamma camera (Ventri, GE Healthcare) with a 15-min acquisition time each for stress and rest. All scans were immediately repeated on an ultrafast CZT camera (Discovery 530 NMc, GE Healthcare) with a 3-min scan time for stress and a 2-min scan time for rest. Clinical agreement (normal, ischaemia, scar) between CZT and SPECT was assessed for each patient and for each coronary territory using SPECT MPI as the reference standard. Segmental myocardial tracer uptake values (percent of maximum) using a 20-segment model and left ventricular ejection fraction (EF) values obtained using CZT were compared with those obtained using conventional SPECT by intraclass correlation and by calculating Bland-Altman limits of agreement. There was excellent clinical agreement between CZT and conventional SPECT on a per-patient basis (96.0%) and on a per-vessel territory basis (96.4%) as shown by a highly significant correlation between segmental tracer uptake values (r=0.901, p<0.001). Similarly, EF values for both scanners were highly correlated (r=0.976, p<0.001) with narrow Bland-Altman limits of agreement (-5.5-10.6%). The novel CZT camera allows a more than fivefold reduction in scan time and provides clinical information equivalent to conventional standard SPECT MPI. (orig.)

  16. In vivo quantification of {sup 177}Lu with planar whole-body and SPECT/CT gamma camera imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Dale L. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Faculty of Health Sciences, University of Sydney, Cumberland, NSW (Australia); Sydney Medical School, University of Sydney, Camperdown, NSW (Australia); NETwork, Sydney Vital, St Leonards, Sydney, NSW (Australia); Hennessy, Thomas M.; Willowson, Kathy P.; Henry, E. Courtney [Institute of Medical Physics, University of Sydney, Camperdown, NSW (Australia); Chan, David L.H. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); NETwork, Sydney Vital, St Leonards, Sydney, NSW (Australia); Aslani, Alireza [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Roach, Paul J. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Sydney Medical School, University of Sydney, Camperdown, NSW (Australia)

    2015-09-17

    Advances in gamma camera technology and the emergence of a number of new theranostic radiopharmaceutical pairings have re-awakened interest in in vivo quantification with single-photon-emitting radionuclides. We have implemented and validated methodology to provide quantitative imaging of {sup 177}Lu for 2D whole-body planar studies and for 3D tomographic imaging with single-photon emission computed tomography (SPECT)/CT. Whole-body planar scans were performed on subjects to whom a known amount of [{sup 177}Lu]-DOTA-octreotate had been administered for therapy. The total radioactivity estimated from the images was compared with the known amount of the radionuclide therapy administered. In separate studies, venous blood samples were withdrawn from subjects after administration of [{sup 177}Lu]-DOTA-octreotate while a SPECT acquisition was in progress and the concentration of the radionuclide in the venous blood sample compared with that estimated from large blood pool structures in the SPECT reconstruction. The total radioactivity contained within an internal SPECT calibration standard was also assessed. In the whole-body planar scans (n = 28), the estimated total body radioactivity was accurate to within +4.6 ± 5.9 % (range −17.1 to +11.2 %) of the correct value. In the SPECT reconstructions (n = 12), the radioactivity concentration in the cardiac blood pool was accurate to within −4.0 ± 7.8 % (range −16.1 to +7.5 %) of the true value and the internal standard measurements (n = 89) were within 2.0 ± 8.5 % (range −16.3 to +24.2 %) of the known amount of radioactivity contained. In our hands, state-of-the-art hybrid SPECT/CT gamma cameras were able to provide accurate estimates of in vivo radioactivity to better than, on average, ±10 % for use in biodistribution and radionuclide dosimetry calculations.

  17. A 2D 4×4 Channel Readout ASIC for Pixelated CdTe Detectors for Medical Imaging Applications

    OpenAIRE

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Martínez, Ricardo; Puigdengoles, Carles

    2015-01-01

    We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The 4 × 4 pixel array ROIC is the proof of concept of the 10 × 10 pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to dig...

  18. Estimation of the Embedding Capacity in Pixel-pair based Watermarking Schemes

    CERN Document Server

    Iyer, Rishabh; Shah, Ronak; Chaudhuri, Subhasis

    2011-01-01

    Estimation of the Embedding capacity is an important problem specifically in reversible multi-pass watermarking and is required for analysis before any image can be watermarked. In this paper, we propose an efficient method for estimating the embedding capacity of a given cover image under multi-pass embedding, without actually embedding the watermark. We demonstrate this for a class of reversible watermarking schemes which operate on a disjoint group of pixels, specifically for pixel pairs. The proposed algorithm iteratively updates the co-occurrence matrix at every stage, to estimate the multi-pass embedding capacity, and is much more efficient vis-a-vis actual watermarking. We also suggest an extremely efficient, pre-computable tree based implementation which is conceptually similar to the co-occurrence based method, but provides the estimates in a single iteration, requiring a complexity akin to that of single pass capacity estimation. We also provide bounds on the embedding capacity. We finally show how ...

  19. Statistical and systematic uncertainties in pixel-based source reconstruction algorithms for gravitational lensing

    CERN Document Server

    Tagore, Amitpal

    2014-01-01

    Gravitational lens modeling of spatially resolved sources is a challenging inverse problem with many observational constraints and model parameters. We examine established pixel-based source reconstruction algorithms for de-lensing the source and constraining lens model parameters. Using test data for four canonical lens configurations, we explore statistical and systematic uncertainties associated with gridding, source regularisation, interpolation errors, noise, and telescope pointing. Specifically, we compare two gridding schemes in the source plane: a fully adaptive grid that follows the lens mapping but is irregular, and an adaptive Cartesian grid. We also consider regularisation schemes that minimise derivatives of the source (using two finite difference methods) and introduce a scheme that minimises deviations from an analytic source profile. Careful choice of gridding and regularisation can reduce "discreteness noise" in the $\\chi^2$ surface that is inherent in the pixel-based methodology. With a grid...

  20. Comparison of Pixel-Based and Object-Oriented Land Cover Change Detection Methods

    Science.gov (United States)

    Xie, Zhenlei; Shi, Ruoming; Zhu, Ling; Peng, Shu; Chen, Xu

    2016-06-01

    Change detection method is an efficient way in the aim of land cover product updating on the basis of the existing products, and at the same time saving lots of cost and time. Considering the object-oriented change detection method for 30m resolution Landsat image, analysis of effect of different segmentation scales on the method of the object-oriented is firstly carried out. On the other hand, for analysing the effectiveness and availability of pixel-based change method, the two indices which complement each other are the differenced Normalized Difference Vegetation Index (dNDVI), the Change Vector (CV) were used. To demonstrate the performance of pixel-based and object-oriented, accuracy assessment of these two change detection results will be conducted by four indicators which include overall accuracy, omission error, commission error and Kappa coefficient.

  1. Fully integrated system-on-chip for pixel-based 3D depth and scene mapping

    Science.gov (United States)

    Popp, Martin; De Coi, Beat; Thalmann, Markus; Gancarz, Radoslav; Ferrat, Pascal; Dürmüller, Martin; Britt, Florian; Annese, Marco; Ledergerber, Markus; Catregn, Gion-Pol

    2012-03-01

    We present for the first time a fully integrated system-on-chip (SoC) for pixel-based 3D range detection suited for commercial applications. It is based on the time-of-flight (ToF) principle, i.e. measuring the phase difference of a reflected pulse train. The product epc600 is fabricated using a dedicated process flow, called Espros Photonic CMOS. This integration makes it possible to achieve a Quantum Efficiency (QE) of >80% in the full wavelength band from 520nm up to 900nm as well as very high timing precision in the sub-ns range which is needed for exact detection of the phase delay. The SoC features 8x8 pixels and includes all necessary sub-components such as ToF pixel array, voltage generation and regulation, non-volatile memory for configuration, LED driver for active illumination, digital SPI interface for easy communication, column based 12bit ADC converters, PLL and digital data processing with temporary data storage. The system can be operated at up to 100 frames per second.

  2. A study of a matching pixel by pixel (MPP) algorithm to establish an empirical model of water quality mapping, as based on unmanned aerial vehicle (UAV) images

    Science.gov (United States)

    Su, Tung-Ching

    2017-06-01

    Linear regression models are a popular choice for the relationships between water quality parameters and bands (or band ratios) of remote sensing data. However, this research regards the phenomena of mixed pixels, specular reflection, and water fluidity as the challenges to establish a robust regression model. Based on the data of measurements in situ and remote sensing data, this study presents an enumeration-based algorithm, called matching pixel by pixel (MPP), and tests its performance in an empirical model of water quality mapping. Four small reservoirs, which cover a mere several hundred-thousand m2, in Kinmen, Taiwan, are selected as the study sites. The multispectral sensors, carried on an unmanned aerial vehicle (UAV), are adopted to acquire remote sensing data regarding water quality parameters, including chlorophyll-a (Chl-a), Secchi disk depth (SDD), and turbidity in the reservoirs. The experimental results indicate that, while MPP can reduce the influence of specular reflection on regression model establishment, specular reflection does hamper the correction of thematic map production. Due to water fluidity, sampling in situ should be followed by UAV imaging as soon as possible. Excluding turbidity, the obtained estimation accuracy can satisfy the national standard.

  3. POLYNOMIAL MODEL BASED FAST FRACTIONAL PIXEL SEARCH ALGORITHM FOR H.264/AVC

    Institute of Scientific and Technical Information of China (English)

    Xi Yinglai; Hao Chongyang; Lai Changcai

    2006-01-01

    This paper proposed a novel fast fractional pixel search algorithm based on polynomial model.With the analysis of distribution characteristics of motion compensation error surface inside fractional pixel searching window, the matching error is fitted with parabola along horizontal and vertical direction respectively. The proposed searching strategy needs to check only 6 points rather than 16 or 24 points, which are used in the Hierarchical Fractional Pel Search algorithm (HFPS) for 1/4-pel and 1/8-pel Motion Estimation (ME). The experimental results show that the proposed algorithm shows very good capability in keeping the rate distortion performance while reduces computation load to a large extent compared with HFPS algorithm.

  4. A Medipix2-based imaging system for digital mammography with silicon pixel detectors

    CERN Document Server

    Bisogni, M G; Fantacci, M E; Mettivier, G; Montesi, M C; Novelli, M; Quattrocchi, M; Rosso, V; Russo, P; Stefanini, A

    2004-01-01

    In this paper we present the first tests of a digital imaging system based on a silicon pixel detector bump-bonded to an integrated circuit operating in single photon counting mode. The X-rays sensor is a 300 mu m thick silicon, 14 by 14 mm/sup 2/, upon which a matrix of 256 * 256 pixels has been built. The read-out chip, named MEDIPIX2, has been developed at CERN within the MEDIPIX2 Collaboration and it is composed by a matrix of 256 * 256 cells, 55 * 55 mu m/sup 2/. The spatial resolution properties of the system have been assessed by measuring the square wave resolution function (SWRF) and first images of a standard mammographic phantom were acquired using a radiographic tube in the clinical irradiation condition. (5 refs).

  5. Detailed study of the column-based priority logic readout of Topmetal-II- CMOS pixel direct charge sensor

    CERN Document Server

    An, Mangmang; Gao, Chaosong; Han, Mikyung; Huang, Guangming; Ji, Rong; Li, Xiaoting; Mei, Yuan; Pei, Hua; Sun, Quan; Sun, Xiangming; Wang, Kai; Xiao, Le; Yang, Ping; Zhang, Wei; Zhou, Wei

    2016-01-01

    We present the detailed study of the digital readout of Topmetal-II- CMOS pixel direct charge sensor. Topmetal-II- is an integrated sensor with an array of 72X72 pixels each capable of directly collecting external charge through exposed metal electrodes in the topmost metal layer. In addition to the time-shared multiplexing readout of the analog output from Charge Sensitive Amplifiers in each pixel, hits are also generated through comparators with individually DAC settable thresholds in each pixel. The hits are read out via a column-based priority logic structure, retaining both hit location and time information. The in-array column-based priority logic is fully combinational hence there is no clock distributed in the pixel array. Sequential logic and clock are placed on the peripheral of the array. We studied the detailed working behavior and performance of this readout, and demonstrated its potential in imaging applications.

  6. Online data reduction with FPGA-based track reconstruction for the Belle II DEPFET pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Deschamps, Bruno; Wessel, Christian; Marinas, Carlos; Dingfelder, Jochen [Physikalisches Institut, Universitaet Bonn (Germany)

    2016-07-01

    The innermost two layers of the Belle II vertex detector at the KEK facility in Tsukuba, Japan, will be covered by high-granularity DEPFET pixel sensors (PXD). The large number of pixels leads to a maximum data rate of 256 Gbps, which has to be significantly reduced by the Data Acquisition System (DATCON). For the data reduction the hit information of the surrounding Silicon strip Vertex Detector (SVD) is utilized to define so-called Regions of Interest (ROI). Only hit information of the pixels located inside these ROIs are saved. The ROIs for the PXD are computed by reconstructing track segments from SVD data and extrapolation to the PXD. The goal is to achieve a data reduction of at least a factor of 10 with this ROI selection. All the necessary processing stages, the receiving, decoding and multiplexing of SVD data on 48 optical fibers, the track reconstruction and the definition of the ROIs, will be performed by the presented system. The planned hardware design is based on a distributed set of Advanced Mezzanine Cards (AMC) each equipped with a Field Programmable Gate Array (FPGA) and 4 optical transceivers. In this talk, the status and plans for the DATCON prototype and the FPGA-based tracking algorithm are introduced as well as the plans for their test in the upcoming test beam at DESY.

  7. Low-power coprocessor for Haar-like feature extraction with pixel-based pipelined architecture

    Science.gov (United States)

    Luo, Aiwen; An, Fengwei; Fujita, Yuki; Zhang, Xiangyu; Chen, Lei; Jürgen Mattausch, Hans

    2017-04-01

    Intelligent analysis of image and video data requires image-feature extraction as an important processing capability for machine-vision realization. A coprocessor with pixel-based pipeline (CFEPP) architecture is developed for real-time Haar-like cell-based feature extraction. Synchronization with the image sensor’s pixel frequency and immediate usage of each input pixel for the feature-construction process avoids the dependence on memory-intensive conventional strategies like integral-image construction or frame buffers. One 180 nm CMOS prototype can extract the 1680-dimensional Haar-like feature vectors, applied in the speeded up robust features (SURF) scheme, using an on-chip memory of only 96 kb (kilobit). Additionally, a low power dissipation of only 43.45 mW at 1.8 V supply voltage is achieved during VGA video procession at 120 MHz frequency with more than 325 fps. The Haar-like feature-extraction coprocessor is further evaluated by the practical application of vehicle recognition, achieving the expected high accuracy which is comparable to previous work.

  8. Online data reduction with FPGA-based track reconstruction for the Belle II DEPFET pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Schnell, Michael; Deschamps, Bruno; Dingfelder, Jochen; Marinas, Carlos [University of Bonn (Germany); Collaboration: Belle II-Collaboration

    2015-07-01

    The innermost two layers of the Belle II vertex detector at the KEK facility in Tsukuba, Japan, will be covered by high-granularity DEPFET pixel sensors (PXD). The large number of pixels leads to a maximum data rate of 256 Gbps, which has to be significantly reduced by the Data Acquisition System. For the data reduction the hit information of the surrounding Silicon strip Vertex Detector (SVD) is utilized to define so-called Regions of Interest (ROI). Only hit information of the pixels located inside these ROIs are saved. The ROIs for the PXD are computed by reconstructing track segments from SVD data and extrapolation to the PXD. The goal is to achieve a data reduction of up to a factor of 10 with this ROI selection. All the necessary processing stages, the receiving, decoding and multiplexing of SVD data on 48 optical fibers, the track reconstruction and the definition of the ROIs, will be performed by the presented system. The planned hardware design is based on a distributed set of Advanced Mezzanine Cards (AMC) each equipped with a Field Programmable Gate Array (FPGA) and 4 optical transceivers. In this talk, the hardware and the FPGA-based tracking algorithm is introduced with some recent performance results from simulation and the latest test beam campaigns.

  9. Toward VIP-PIX: A Low Noise Readout ASIC for Pixelated CdTe Gamma-Ray Detectors for Use in the Next Generation of PET Scanners

    OpenAIRE

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Puigdengoles, Carles; Lorenzo, Gianluca De; Martínez, Ricardo

    2013-01-01

    VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-...

  10. A robust sub-pixel edge detection method of infrared image based on tremor-based retinal receptive field model

    Science.gov (United States)

    Gao, Kun; Yang, Hu; Chen, Xiaomei; Ni, Guoqiang

    2008-03-01

    Because of complex thermal objects in an infrared image, the prevalent image edge detection operators are often suitable for a certain scene and extract too wide edges sometimes. From a biological point of view, the image edge detection operators work reliably when assuming a convolution-based receptive field architecture. A DoG (Difference-of- Gaussians) model filter based on ON-center retinal ganglion cell receptive field architecture with artificial eye tremors introduced is proposed for the image contour detection. Aiming at the blurred edges of an infrared image, the subsequent orthogonal polynomial interpolation and sub-pixel level edge detection in rough edge pixel neighborhood is adopted to locate the foregoing rough edges in sub-pixel level. Numerical simulations show that this method can locate the target edge accurately and robustly.

  11. Hybrid Pixel-Based Method for Cardiac Ultrasound Fusion Based on Integration of PCA and DWT

    Directory of Open Access Journals (Sweden)

    Samaneh Mazaheri

    2015-01-01

    Full Text Available Medical image fusion is the procedure of combining several images from one or multiple imaging modalities. In spite of numerous attempts in direction of automation ventricle segmentation and tracking in echocardiography, due to low quality images with missing anatomical details or speckle noises and restricted field of view, this problem is a challenging task. This paper presents a fusion method which particularly intends to increase the segment-ability of echocardiography features such as endocardial and improving the image contrast. In addition, it tries to expand the field of view, decreasing impact of noise and artifacts and enhancing the signal to noise ratio of the echo images. The proposed algorithm weights the image information regarding an integration feature between all the overlapping images, by using a combination of principal component analysis and discrete wavelet transform. For evaluation, a comparison has been done between results of some well-known techniques and the proposed method. Also, different metrics are implemented to evaluate the performance of proposed algorithm. It has been concluded that the presented pixel-based method based on the integration of PCA and DWT has the best result for the segment-ability of cardiac ultrasound images and better performance in all metrics.

  12. A pixel-based color image segmentation using support vector machine and fuzzy C-means.

    Science.gov (United States)

    Wang, Xiang-Yang; Zhang, Xian-Jin; Yang, Hong-Ying; Bu, Juan

    2012-09-01

    Image segmentation is an important tool in image processing and can serve as an efficient front end to sophisticated algorithms and thereby simplify subsequent processing. In this paper, we present a pixel-based color image segmentation using Support Vector Machine (SVM) and Fuzzy C-Means (FCM). Firstly, the pixel-level color feature and texture feature of the image, which is used as input of the SVM model (classifier), are extracted via the local spatial similarity measure model and Steerable filter. Then, the SVM model (classifier) is trained by using FCM with the extracted pixel-level features. Finally, the color image is segmented with the trained SVM model (classifier). This image segmentation can not only take full advantage of the local information of the color image but also the ability of the SVM classifier. Experimental evidence shows that the proposed method has a very effective computational behavior and effectiveness, and decreases the time and increases the quality of color image segmentation in comparison with the state-of-the-art segmentation methods recently proposed in the literature.

  13. a Novel Sub-Pixel Matching Algorithm Based on Phase Correlation Using Peak Calculation

    Science.gov (United States)

    Xie, Junfeng; Mo, Fan; Yang, Chao; Li, Pin; Tian, Shiqiang

    2016-06-01

    The matching accuracy of homonymy points of stereo images is a key point in the development of photogrammetry, which influences the geometrical accuracy of the image products. This paper presents a novel sub-pixel matching method phase correlation using peak calculation to improve the matching accuracy. The peak theoretic centre that means to sub-pixel deviation can be acquired by Peak Calculation (PC) according to inherent geometrical relationship, which is generated by inverse normalized cross-power spectrum, and the mismatching points are rejected by two strategies: window constraint, which is designed by matching window and geometric constraint, and correlation coefficient, which is effective for satellite images used for mismatching points removing. After above, a lot of high-precise homonymy points can be left. Lastly, three experiments are taken to verify the accuracy and efficiency of the presented method. Excellent results show that the presented method is better than traditional phase correlation matching methods based on surface fitting in these aspects of accuracy and efficiency, and the accuracy of the proposed phase correlation matching algorithm can reach 0.1 pixel with a higher calculation efficiency.

  14. Single-pixel three-dimensional imaging with time-based depth resolution

    Science.gov (United States)

    Sun, Ming-Jie; Edgar, Matthew P.; Gibson, Graham M.; Sun, Baoqing; Radwell, Neal; Lamb, Robert; Padgett, Miles J.

    2016-07-01

    Time-of-flight three-dimensional imaging is an important tool for applications such as object recognition and remote sensing. Conventional time-of-flight three-dimensional imaging systems frequently use a raster scanned laser to measure the range of each pixel in the scene sequentially. Here we show a modified time-of-flight three-dimensional imaging system, which can use compressed sensing techniques to reduce acquisition times, whilst distributing the optical illumination over the full field of view. Our system is based on a single-pixel camera using short-pulsed structured illumination and a high-speed photodiode, and is capable of reconstructing 128 × 128-pixel resolution three-dimensional scenes to an accuracy of ~3 mm at a range of ~5 m. Furthermore, by using a compressive sampling strategy, we demonstrate continuous real-time three-dimensional video with a frame-rate up to 12 Hz. The simplicity of the system hardware could enable low-cost three-dimensional imaging devices for precision ranging at wavelengths beyond the visible spectrum.

  15. Dependence of the appearance-based perception of criminality, suggestibility, and trustworthiness on the level of pixelation of facial images.

    Science.gov (United States)

    Nurmoja, Merle; Eamets, Triin; Härma, Hanne-Loore; Bachmann, Talis

    2012-10-01

    While the dependence of face identification on the level of pixelation-transform of the images of faces has been well studied, similar research on face-based trait perception is underdeveloped. Because depiction formats used for hiding individual identity in visual media and evidential material recorded by surveillance cameras often consist of pixelized images, knowing the effects of pixelation on person perception has practical relevance. Here, the results of two experiments are presented showing the effect of facial image pixelation on the perception of criminality, trustworthiness, and suggestibility. It appears that individuals (N = 46, M age = 21.5 yr., SD = 3.1 for criminality ratings; N = 94, M age = 27.4 yr., SD = 10.1 for other ratings) have the ability to discriminate between facial cues ndicative of these perceived traits from the coarse level of image pixelation (10-12 pixels per face horizontally) and that the discriminability increases with a decrease in the coarseness of pixelation. Perceived criminality and trustworthiness appear to be better carried by the pixelized images than perceived suggestibility.

  16. Examining Multi-Legend Change Detection in Amazon with Pixel and Region Based Methods

    Directory of Open Access Journals (Sweden)

    Mariane S. Reis

    2017-01-01

    Full Text Available Post-classification comparison is one of the most widely used change detection methods. However, it presents several operational problems that are often ignored, such as the occurrence of impossible transitions, difficulties in accuracy assessment and results not accurate enough for the purpose. This work aims to evaluate post-classification comparison change detection results obtained from LANDSAT5/TM data in a region of the Brazilian Amazon, using three legends in different levels of detail and both pixel wise and region based classifiers. A distinctive characteristic of the used approach is that each change mapping is the result of the combination of 100 land cover classifications for each date, obtained using varied training samples. This approach allowed to account for the training samples choice into the methodology, as well as the construction of confidence mappings. We presented and discussed different approaches for evaluating change results, such as the likelihood of land cover transitions occurring within the study area and time gap, the use of rectangular matrices to incorporate the occurrence of impossible or non evaluable changes and classification uncertainty. In general, change mappings obtained from region based classifications showed better results than the ones obtained from pixel based classifications. Globally, the use of region based approaches, in contrast to pixel based ones, led to an increase in accuracy of 15.5% for the change mapping from the most detailed legend, 7.8% for the one with the legend with intermediate level of detail and 3.6% for the less detailed one. In addition, individual transitions between land cover classes were better identified using region based approaches, with the exception of transitions from a non agriculture class to an agricultural one. The proposed quality mappings are useful to help to evaluate the change mappings, mainly in legend levels with higher level of detail and if reference

  17. GEM400: A front-end chip based on capacitor-switch array for pixel-based GEM detector

    Science.gov (United States)

    Li, H. S.; Jiang, X. S.; Liu, G.; Wang, N.; Sheng, H. Y.; Zhuang, B. A.; Zhao, J. W.

    2012-03-01

    The upgrade of Beijing Synchrotron Radiation Facility (BSRF) needs two-dimensional position-sensitive detection equipment to improve the experimental performance. Gas Electron Multiplier (GEM) detector, in particular, pixel-based GEM detector has good application prospects in the domain of synchrotron radiation. The read-out of larger scale pixel-based GEM detector is difficult for the high density of the pixels (PAD for collecting electrons). In order to reduce the number of cables, this paper presents a read-out scheme for pixel-based GEM detector, which is based on System-in-Package technology and ASIC technology. We proposed a circuit structure based on capacitor switch array circuit, and design a chip GEM400, which is a 400 channels ASIC. The proposed circuit can achieve good stability and low power dissipation. The chip is implemented in a 0.35μm CMOS process. The basic functional circuitry in ths chip includes analog switch, analog buffer, voltage amplifier, bandgap and control logic block, and the layout of this chip takes 5mm × 5mm area. The simulation results show that the chip can allow the maximum amount of input charge 70pC on the condition of 100pF external integrator capacitor. Besides, the chip has good channel uniformity (INL is better than 0.1%) and lower power dissipation.

  18. Connotations of pixel-based scale effect in remote sensing and the modified fractal-based analysis method

    Science.gov (United States)

    Feng, Guixiang; Ming, Dongping; Wang, Min; Yang, Jianyu

    2017-06-01

    Scale problems are a major source of concern in the field of remote sensing. Since the remote sensing is a complex technology system, there is a lack of enough cognition on the connotation of scale and scale effect in remote sensing. Thus, this paper first introduces the connotations of pixel-based scale and summarizes the general understanding of pixel-based scale effect. Pixel-based scale effect analysis is essentially important for choosing the appropriate remote sensing data and the proper processing parameters. Fractal dimension is a useful measurement to analysis pixel-based scale. However in traditional fractal dimension calculation, the impact of spatial resolution is not considered, which leads that the scale effect change with spatial resolution can't be clearly reflected. Therefore, this paper proposes to use spatial resolution as the modified scale parameter of two fractal methods to further analyze the pixel-based scale effect. To verify the results of two modified methods (MFBM (Modified Windowed Fractal Brownian Motion Based on the Surface Area) and MDBM (Modified Windowed Double Blanket Method)); the existing scale effect analysis method (information entropy method) is used to evaluate. And six sub-regions of building areas and farmland areas were cut out from QuickBird images to be used as the experimental data. The results of the experiment show that both the fractal dimension and information entropy present the same trend with the decrease of spatial resolution, and some inflection points appear at the same feature scales. Further analysis shows that these feature scales (corresponding to the inflection points) are related to the actual sizes of the geo-object, which results in fewer mixed pixels in the image, and these inflection points are significantly indicative of the observed features. Therefore, the experiment results indicate that the modified fractal methods are effective to reflect the pixel-based scale effect existing in remote sensing

  19. An Algorithm of Image Contrast Enhancement Based on Pixels Neighborhood’s Local Feature

    Directory of Open Access Journals (Sweden)

    Chen Yan

    2013-12-01

    Full Text Available In this study, we proposed an algorithm of Image Contrast enhancement based on local feature to acquire edge information of image, remove Ray Imaging noise and overcome edge blurry and other defects. This method can extract edge features and finish contrast enhancement in varying degrees for pixels neighborhood with different characteristics by using neighborhood local variance and complexity function, which can achieve local features enhancement. The stimulation shows that the method can not only enhance the contrast of the entire image, but also effectively preserves image edge information and improve image quality.

  20. Study of micro pixel photon counters for a high granularity scintillator-based hadron calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    D' Ascenzo, N. [Hamburg Univ. (Germany)]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Eggemann, A.; Garutti, E. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2007-11-15

    A new Geiger mode avalanche photodiode, the Micro Pixel Photon Counter (MPPC), was recently released by Hamamatsu. It has a high photo-detection efficiency in the 420 nm spectral region. This product can represent an elegant candidate for the design of a high granularity scintillator based hadron calorimeter for the International Linear Collider. In fact, the direct readout of the blue scintillation photons with a MPPC is a feasible techological solution. The readout of a plastic scintillator by a MPPC, both mediated by the traditional wavelength shifting fiber, and directly coupled, has been systematically studied. (orig.)

  1. Methods for Quantifying and Characterizing Errors in Pixel-Based 3D Rendering.

    Science.gov (United States)

    Hagedorn, John G; Terrill, Judith E; Peskin, Adele P; Filliben, James J

    2008-01-01

    We present methods for measuring errors in the rendering of three-dimensional points, line segments, and polygons in pixel-based computer graphics systems. We present error metrics for each of these three cases. These methods are applied to rendering with OpenGL on two common hardware platforms under several rendering conditions. Results are presented and differences in measured errors are analyzed and characterized. We discuss possible extensions of this error analysis approach to other aspects of the process of generating visual representations of synthetic scenes.

  2. Inverse log polar transformation algorithm based on sub-pixel interpolation

    Institute of Scientific and Technical Information of China (English)

    WANG Qi; LI Yan-jun; ZHANG Ke; XIONG Xian-ze

    2006-01-01

    Log polar transformation is an important algorithm of space-variant vision theory.It well depicts the retino-cortical mapping.Due to the logarithmic and the arctangent operation in the transformation,the log polar coordinate of an image is mostly a decimal fraction and the range is quite narrow.Aiming at solving these problems,this paper puts forward an inverse log polar transformation based on sub-pixel interpolation.The acquired log polar image of the new algorithm has no mosaic phenomenon,meanwhile it is a better simulation of retina-cortical mapping.

  3. A New Adaptive Diffusive Function for Magnetic Resonance Imaging Denoising Based on Pixel Similarity.

    Science.gov (United States)

    Heydari, Mostafa; Karami, Mohammad Reza

    2015-01-01

    Although there are many methods for image denoising, but partial differential equation (PDE) based denoising attracted much attention in the field of medical image processing such as magnetic resonance imaging (MRI). The main advantage of PDE-based denoising approach is laid in its ability to smooth image in a nonlinear way, which effectively removes the noise, as well as preserving edge through anisotropic diffusion controlled by the diffusive function. This function was first introduced by Perona and Malik (P-M) in their model. They proposed two functions that are most frequently used in PDE-based methods. Since these functions consider only the gradient information of a diffused pixel, they cannot remove noise in noisy images with low signal-to-noise (SNR). In this paper we propose a modified diffusive function with fractional power that is based on pixel similarity to improve P-M model for low SNR. We also will show that our proposed function will stabilize the P-M method. As experimental results show, our proposed function that is modified version of P-M function effectively improves the SNR and preserves edges more than P-M functions in low SNR.

  4. Intraoperative Scintigraphy Using a Large Field-of-View Portable Gamma Camera for Primary Hyperparathyroidism: Initial Experience

    Directory of Open Access Journals (Sweden)

    Nathan C. Hall

    2015-01-01

    Full Text Available Background. We investigated a novel technique, intraoperative 99 mTc-Sestamibi (MIBI imaging (neck and excised specimen (ES, using a large field-of-view portable gamma camera (LFOVGC, for expediting confirmation of MIBI-avid parathyroid adenoma removal. Methods. Twenty patients with MIBI-avid parathyroid adenomas were preoperatively administered MIBI and intraoperatively imaged prior to incision (neck and immediately following resection (neck and/or ES. Preoperative and intraoperative serum parathyroid hormone monitoring (IOPTH and pathology (path were also performed. Results. MIBI neck activity was absent and specimen activity was present in 13/20 with imaging after initial ES removal. In the remaining 7/20 cases, residual neck activity and/or absent ES activity prompted excision of additional tissue, ultimately leading to complete hyperfunctioning tissue excision. Postexcision LFOVGC ES imaging confirmed parathyroid adenoma resection 100% when postresection imaging qualitatively had activity (ES and/or no activity (neck. The mean ± SEM time saving using intraoperative LFOVGC data to confirm resection versus first IOPTH or path result would have been 22.0 ± 2 minutes (specimen imaging and 26.0 ± 3 minutes (neck imaging. Conclusion. Utilization of a novel real-time intraoperative LFOVGC imaging approach can provide confirmation of MIBI-avid parathyroid adenoma removal appreciably faster than IOPTH and/or path and may provide a valuable adjunct to parathyroid surgery.

  5. Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera.

    Science.gov (United States)

    Morozov, A; Alves, F; Marcos, J; Martins, R; Pereira, L; Solovov, V; Chepel, V

    2017-02-13

    Compact gamma cameras with a square-shaped monolithic scintillator crystal and an array of silicon photomultipliers (SiPMs) are actively being developed for applications in areas such as small animal imaging, cancer diagnostics and radiotracer guided surgery. Statistical methods of position reconstruction, which are potentially superior to the traditional centroid method, require accurate knowledge of the spatial response of each photomultiplier. Using both Monte Carlo simulations and experimental data obtained with a camera prototype, we show that the spatial response of all photomultipliers (light response functions) can be parameterized with axially symmetric functions obtained iteratively from flood field irradiation data. The study was performed with a camera prototype equipped with a 30  ×  30  ×  2 mm(3) LYSO crystal and an 8  ×  8 array of SiPMs for 140 keV gamma rays. The simulations demonstrate that the images, reconstructed with the maximum likelihood method using the response obtained with the iterative approach, exhibit only minor distortions: the average difference between the reconstructed and the true positions in X and Y directions does not exceed 0.2 mm in the central area of 22  ×  22 mm(2) and 0.4 mm at the periphery of the camera. A similar level of image distortions is shown experimentally with the camera prototype.

  6. Assessment of spleen size using gamma camera scintigraphy in newly diagnosed patients with essential thrombocythaemia and polycythaemia vera

    Energy Technology Data Exchange (ETDEWEB)

    Carneskog, J.; Wadenvik, H.; Kutti, J. [Univ. of Goeteborg, Sahlgrenska Univ. Hospital, Dept. of Medicine, Haematology Section, Goeteborg (Sweden); Fjaeelling, M. [Univ. of Goeteborg, Sahlgrenska Univ. Hospital, Dept. of Clinical Physiology, Section of Nuclear Med., Goeteborg (Sweden)

    1996-03-01

    By using gamma camera imaging the spleen size was assessed in 18 consecutive patients with essential thrombocythaemia (ET) and in 18 consecutive patients with polycythaemia vera (PV). All ET and PV patients were newly diagnosed and had not received any myelosuppressive therapy prior to study. The spleen areas in both posterior and left lateral projections were determined. Eighteen consecutive patients with idiopathic thrombocytopenic purpura (ITP) served as a control group since by definition they do not present with splenic enlargement; in these latter subjects the mean posterior and left lateral splenic areas were almost identical (48 {+-} 15 and 47 {+-} 17 cm{sup 2}, respectively). In comparison with this control group patients with ET an dPV had significantly larger spleens. In both ET and in PV patients the left lateral spleen scan area exceeded the posterior one. Patients with PV had larger splenic areas in both projections than did patients with ET, but the differences were not statistically significant. Compared to the ITP patients it was found that at least 50% of the ET patients and at least 61% of the PV patients at diagnosis presented with splenomegaly. (au) 35 refs.

  7. Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera

    Science.gov (United States)

    Morozov, A.; Alves, F.; Marcos, J.; Martins, R.; Pereira, L.; Solovov, V.; Chepel, V.

    2017-05-01

    Compact gamma cameras with a square-shaped monolithic scintillator crystal and an array of silicon photomultipliers (SiPMs) are actively being developed for applications in areas such as small animal imaging, cancer diagnostics and radiotracer guided surgery. Statistical methods of position reconstruction, which are potentially superior to the traditional centroid method, require accurate knowledge of the spatial response of each photomultiplier. Using both Monte Carlo simulations and experimental data obtained with a camera prototype, we show that the spatial response of all photomultipliers (light response functions) can be parameterized with axially symmetric functions obtained iteratively from flood field irradiation data. The study was performed with a camera prototype equipped with a 30  ×  30  ×  2 mm3 LYSO crystal and an 8  ×  8 array of SiPMs for 140 keV gamma rays. The simulations demonstrate that the images, reconstructed with the maximum likelihood method using the response obtained with the iterative approach, exhibit only minor distortions: the average difference between the reconstructed and the true positions in X and Y directions does not exceed 0.2 mm in the central area of 22  ×  22 mm2 and 0.4 mm at the periphery of the camera. A similar level of image distortions is shown experimentally with the camera prototype.

  8. Pixel Vertex Detectors

    OpenAIRE

    Wermes, Norbert

    2006-01-01

    Pixel vertex detectors are THE instrument of choice for the tracking of charged particles close to the interaction point at the LHC. Hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as ...

  9. Controlling bridging and pinching with pixel-based mask for inverse lithography

    Science.gov (United States)

    Kobelkov, Sergey; Tritchkov, Alexander; Han, JiWan

    2016-03-01

    Inverse Lithography Technology (ILT) has become a viable computational lithography candidate in recent years as it can produce mask output that results in process latitude and CD control in the fab that is hard to match with conventional OPC/SRAF insertion approaches. An approach to solving the inverse lithography problem as a nonlinear, constrained minimization problem over a domain mask pixels was suggested in the paper by Y. Granik "Fast pixel-based mask optimization for inverse lithography" in 2006. The present paper extends this method to satisfy bridging and pinching constraints imposed on print contours. Namely, there are suggested objective functions expressing penalty for constraints violations, and their minimization with gradient descent methods is considered. This approach has been tested with an ILT-based Local Printability Enhancement (LPTM) tool in an automated flow to eliminate hotspots that can be present on the full chip after conventional SRAF placement/OPC and has been applied in 14nm, 10nm node production, single and multiple-patterning flows.

  10. New mannequin for the measurement of the resolution time in gamma cameras; Nuevo manique para la medida de la resolucion temporal en gammacamaras

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-torres, M.; Torres, J.; Vega, J. M. de la; Ramirez, J. C.; Guirado, D.

    2015-07-01

    The assessment of the resolution temporary is a of the testing recommended on the control of quality of a gamma camera, usually is made by the method of the two sources using the mannequin of Adams, that has thickness of PMMA different to the sides of the sources the that not allows measure simultaneously in the same conditions in gamma cameras of double head. Is simple, not however, build a mannequin economic that this the same configuration of the sources to the two sides, of way that is can measuring the time dead of two heads simultaneously. The goal of East work is set the dimensions and way, of a mannequin of new design of such way that produce the same spectrum that the of Adams. (Author)

  11. The detective quantum efficiency (DQE) for evaluating the performance of a small gamma camera system with a uniformly redundant array (URA) collimator

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Hosang [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Cho, Gyuseong [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)], E-mail: gscho@kaist.ac.kr

    2008-06-11

    Presently, the gamma scintillation camera is widely used in various industrial, environmental and medical diagnostic fields. Hence, the objective and quantitative evaluation of its imaging performance is required for imaging quality assurance and excessive exposures prevention. In this study, the detective quantum efficiency (DQE) of a small gamma camera with three pinholes (1, 2, and 4 mm in hole diameter) and one-coded aperture (uniformly redundant array (URA); 286 holes, hole diameter 2 mm) collimator was determined using modulation transfer function (MTF), normalized noise power spectrum (NNPS), and incoming signal-to-noise ratio (SNR). We found that the resolution of URA was a little lower than that of the pinhole, 2 mm in hole diameter, and the noise of URA was prominently lower than that of all pinholes. Thus, the DQE of URA was higher than that of the pinhole. We found that the determination of DQE could be a quantitative and effective method to evaluate gamma camera systems performances.

  12. Use of calibration methodology of gamma cameras for the workers surveillance using a thyroid simulator; Uso de una metodologia de calibracion de camaras gamma para la vigilancia de trabajadores usando un simulador de tiroides

    Energy Technology Data Exchange (ETDEWEB)

    Alfaro, M.; Molina, G.; Vazquez, R.; Garcia, O., E-mail: mercedes.alfaro@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2010-09-15

    In Mexico there are a significant number of nuclear medicine centers in operation. For what the accidents risk related to the transport and manipulation of open sources used in nuclear medicine can exist. The National Institute of Nuclear Research (ININ) has as objective to establish a simple and feasible methodology for the workers surveillance related with the field of the nuclear medicine. This radiological surveillance can also be applied to the public in the event of a radiological accident. To achieve this it intends to use the available equipment s in the nuclear medicine centers, together with the neck-thyroid simulators elaborated by the ININ to calibrate the gamma cameras. The gamma cameras have among their component elements that conform spectrometric systems like the employees in the evaluation of the internal incorporation for direct measurements, reason why, besides their use for diagnostic for image, they can be calibrated with anthropomorphic simulators and also with punctual sources for the quantification of the radionuclides activity distributed homogeneously in the human body, or located in specific organs. Inside the project IAEA-ARCAL-RLA/9/049-LXXVIII -Procedures harmonization of internal dosimetry- where 9 countries intervened (Argentina, Brazil, Colombia, Cuba, Chile, Mexico, Peru, Uruguay and Spain). It was developed a protocol of cameras gamma calibration for the determination in vivo of radionuclides. The protocol is the base to establish and integrated network in Latin America to attend in response to emergencies, using nuclear medicine centers of public hospitals of the region. The objective is to achieve the appropriate radiological protection of the workers, essential for the sure and acceptable radiation use, the radioactive materials and the nuclear energy. (Author)

  13. [Evaluation of the efficacy of sentinel node detection in breast cancer: chronological course and influence of the incorporation of an intra-operative portable gamma camera].

    Science.gov (United States)

    Goñi Gironés, E; Vicente García, F; Serra Arbeloa, P; Estébanez Estébanez, C; Calvo Benito, A; Rodrigo Rincón, I; Camarero Salazar, A; Martínez Lozano, M E

    2013-01-01

    To define the sentinel node identification rate in breast cancer, the chronological evolution of this parameter and the influence of the introduction of a portable gamma camera. A retrospective study was conducted using a prospective database of 754 patients who had undergone a sentinel lymph node biopsy between January 2003 and December 2011. The technique was mixed in the starting period and subsequently was performed with radiotracer intra-peritumorally administered the day before of the surgery. Until October 2009, excision of the sentinel node was guided by a probe. After that date, a portable gamma camera was introduced for intrasurgical detection. The SN was biopsied in 725 out of the 754 patients studied. The resulting technique global effectiveness was 96.2%. In accordance with the year of the surgical intervention, the identification percentage was 93.5% in 2003, 88.7% in 2004, 94.3% in 2005, 95.7% in 2006, 93.3% in 2007, 98.8% in 2008, 97.1% in 2009 and 99.1% in 2010 and 2011. There was a significant difference in the proportion of identification before and after the incorporation of the portable gamma camera of 4.6% (95% CI of the difference 2-7.2%, P = 0.0037). The percentage of global identification exceeds the recommended level following the current guidelines. Chronologically, the improvement for this parameter during the study period has been observed. These data suggest that the incorporation of a portable gamma camera had an important role. Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.

  14. Performance of the Insertable B-Layer for the ATLAS Pixel Detector during Quality Assurance and a Novel Pixel Detector Readout Concept based on PCIe

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00356268; Pernegger, Heinz

    2016-07-27

    During the first long shutdown of the LHC the Pixel detector has been upgraded with a new 4th innermost layer, the Insertable B-Layer (IBL). The IBL will increase the tracking performance and help with higher than nominal luminosity the LHC will produce. The IBL is made up of 14 staves and in total 20 staves have been produced for the IBL. This thesis presents the results of the final quality tests performed on these staves in an detector-like environment, in order to select the 14 best of the 20 staves for integration onto the detector. The test setup as well as the testing procedure is introduced and typical results of each testing stage are shown and discussed. The overall performance of all staves is presented in regards to: tuning performance, radioactive source measurements, and number of failing pixels. Other measurement, which did not directly impact the selection of staves, but will be important for the operation of the detector or production of a future detector, are included. Based on the experienc...

  15. Fusion of Pixel-based and Object-based Features for Road Centerline Extraction from High-resolution Satellite Imagery

    Directory of Open Access Journals (Sweden)

    CAO Yungang

    2016-10-01

    Full Text Available A novel approach for road centerline extraction from high spatial resolution satellite imagery is proposed by fusing both pixel-based and object-based features. Firstly, texture and shape features are extracted at the pixel level, and spectral features are extracted at the object level based on multi-scale image segmentation maps. Then, extracted multiple features are utilized in the fusion framework of Dempster-Shafer evidence theory to roughly identify the road network regions. Finally, an automatic noise removing algorithm combined with the tensor voting strategy is presented to accurately extract the road centerline. Experimental results using high-resolution satellite imageries with different scenes and spatial resolutions showed that the proposed approach compared favorably with the traditional methods, particularly in the aspect of eliminating the salt noise and conglutination phenomenon.

  16. Monte Carlo based performance assessment of different animal PET architectures using pixellated CZT detectors

    Energy Technology Data Exchange (ETDEWEB)

    Visvikis, D. [INSERM U650, LaTIM, University Hospital Medical School, F-29609 Brest (France)]. E-mail: Visvikis.Dimitris@univ-brest.fr; Lefevre, T. [INSERM U650, LaTIM, University Hospital Medical School, F-29609 Brest (France); Lamare, F. [INSERM U650, LaTIM, University Hospital Medical School, F-29609 Brest (France); Kontaxakis, G. [ETSI Telecomunicacion Universidad Politecnica de Madrid, Ciudad Universitaria, s/n 28040, Madrid (Spain); Santos, A. [ETSI Telecomunicacion Universidad Politecnica de Madrid, Ciudad Universitaria, s/n 28040, Madrid (Spain); Darambara, D. [Department of Physics, School of Engineering and Physical Sciences, University of Surrey, Guildford (United Kingdom)

    2006-12-20

    The majority of present position emission tomography (PET) animal systems are based on the coupling of high-density scintillators and light detectors. A disadvantage of these detector configurations is the compromise between image resolution, sensitivity and energy resolution. In addition, current combined imaging devices are based on simply placing back-to-back and in axial alignment different apparatus without any significant level of software or hardware integration. The use of semiconductor CdZnTe (CZT) detectors is a promising alternative to scintillators for gamma-ray imaging systems. At the same time CZT detectors have the potential properties necessary for the construction of a truly integrated imaging device (PET/SPECT/CT). The aims of this study was to assess the performance of different small animal PET scanner architectures based on CZT pixellated detectors and compare their performance with that of state of the art existing PET animal scanners. Different scanner architectures were modelled using GATE (Geant4 Application for Tomographic Emission). Particular scanner design characteristics included an overall cylindrical scanner format of 8 and 24 cm in axial and transaxial field of view, respectively, and a temporal coincidence window of 8 ns. Different individual detector modules were investigated, considering pixel pitch down to 0.625 mm and detector thickness from 1 to 5 mm. Modified NEMA NU2-2001 protocols were used in order to simulate performance based on mouse, rat and monkey imaging conditions. These protocols allowed us to directly compare the performance of the proposed geometries with the latest generation of current small animal systems. Results attained demonstrate the potential for higher NECR with CZT based scanners in comparison to scintillator based animal systems.

  17. [Evaluation of crossing calibration of (123)I-MIBG H/M ration, with the IDW scatter correction method, on different gamma camera systems].

    Science.gov (United States)

    Kittaka, Daisuke; Takase, Tadashi; Akiyama, Masayuki; Nakazawa, Yasuo; Shinozuka, Akira; Shirai, Muneaki

    2011-01-01

    (123)I-MIBG Heart-to-Mediastinum activity ratio (H/M) is commonly used as an indicator of relative myocardial (123)I-MIBG uptake. H/M ratios reflect myocardial sympathetic nerve function, therefore it is a useful parameter to assess regional myocardial sympathetic denervation in various cardiac diseases. However, H/M ratio values differ by site, gamma camera system, position and size of region of interest (ROI), and collimator. In addition to these factors, 529 keV scatter component may also affect (123)I-MIBG H/M ratio. In this study, we examined whether the H/M ratio shows correlation between two different gamma camera systems and that sought for H/M ratio calculation formula. Moreover, we assessed the feasibility of (123)I Dual Window (IDW) method, which is a scatter correction method, and compared H/M ratios with and without IDW method. H/M ratio displayed a good correlation between two gamma camera systems. Additionally, we were able to create a new H/M calculation formula. These results indicated that the IDW method is a useful scatter correction method for calculating (123)I-MIBG H/M ratios.

  18. Pixel Experiments

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Augustesen, Christina

    2015-01-01

    Pixel Experiments The term pixel is traditionally defined as any of the minute elements that together constitute a larger context or image. A pixel has its own form and is the smallest unit seen within a larger structure. In working with the potentials of LED technology in architectural lighting...... design it became relevant to investigate the use of LEDs as the physical equivalent of a pixel as a design approach. In this book our interest has been in identifying how the qualities of LEDs can be used in lighting applications. With experiences in the planning and implementation of architectural...... elucidate and exemplify already well-known problems in relation to the experience of vertical and horizontal lighting. Pixel Experiments exist as a synergy between speculative test setups and lighting design in practice. This book is one of four books that is published in connection with the research...

  19. Pixelated CdTe detectors to overcome intrinsic limitations of crystal based positron emission mammographs

    Science.gov (United States)

    De Lorenzo, G.; Chmeissani, M.; Uzun, D.; Kolstein, M.; Ozsahin, I.; Mikhaylova, E.; Arce, P.; Cañadas, M.; Ariño, G.; Calderón, Y.

    2013-01-01

    A positron emission mammograph (PEM) is an organ dedicated positron emission tomography (PET) scanner for breast cancer detection. State-of-the-art PEMs employing scintillating crystals as detection medium can provide metabolic images of the breast with significantly higher sensitivity and specificity with respect to standard whole body PET scanners. Over the past few years, crystal PEMs have dramatically increased their importance in the diagnosis and treatment of early stage breast cancer. Nevertheless, designs based on scintillators are characterized by an intrinsic deficiency of the depth of interaction (DOI) information from relatively thick crystals constraining the size of the smallest detectable tumor. This work shows how to overcome such intrinsic limitation by substituting scintillating crystals with pixelated CdTe detectors. The proposed novel design is developed within the Voxel Imaging PET (VIP) Pathfinder project and evaluated via Monte Carlo simulation. The volumetric spatial resolution of the VIP-PEM is expected to be up to 6 times better than standard commercial devices with a point spread function of 1 mm full width at half maximum (FWHM) in all directions. Pixelated CdTe detectors can also provide an energy resolution as low as 1.5% FWHM at 511 keV for a virtually pure signal with negligible contribution from scattered events.

  20. A kilo-pixel imaging system for future space based far-infrared observatories using microwave kinetic inductance detectors

    Science.gov (United States)

    Baselmans, J. J. A.; Bueno, J.; Yates, S. J. C.; Yurduseven, O.; Llombart, N.; Karatsu, K.; Baryshev, A. M.; Ferrari, L.; Endo, A.; Thoen, D. J.; de Visser, P. J.; Janssen, R. M. J.; Murugesan, V.; Driessen, E. F. C.; Coiffard, G.; Martin-Pintado, J.; Hargrave, P.; Griffin, M.

    2017-05-01

    Aims: Future astrophysics and cosmic microwave background space missions operating in the far-infrared to millimetre part of the spectrum will require very large arrays of ultra-sensitive detectors in combination with high multiplexing factors and efficient low-noise and low-power readout systems. We have developed a demonstrator system suitable for such applications. Methods: The system combines a 961 pixel imaging array based upon Microwave Kinetic Inductance Detectors (MKIDs) with a readout system capable of reading out all pixels simultaneously with only one readout cable pair and a single cryogenic amplifier. We evaluate, in a representative environment, the system performance in terms of sensitivity, dynamic range, optical efficiency, cosmic ray rejection, pixel-pixel crosstalk and overall yield at an observation centre frequency of 850 GHz and 20% fractional bandwidth. Results: The overall system has an excellent sensitivity, with an average detector sensitivity =3×10-19 WHz measured using a thermal calibration source. At a loading power per pixel of 50 fW we demonstrate white, photon noise limited detector noise down to 300 mHz. The dynamic range would allow the detection of 1 Jy bright sources within the field of view without tuning the readout of the detectors. The expected dead time due to cosmic ray interactions, when operated in an L2 or a similar far-Earth orbit, is found to be <4%. Additionally, the achieved pixel yield is 83% and the crosstalk between the pixels is <-30 dB. Conclusions: This demonstrates that MKID technology can provide multiplexing ratios on the order of a 1000 with state-of-the-art single pixel performance, and that the technology is now mature enough to be considered for future space based observatories and experiments.

  1. Compressive Video Recovery Using Block Match Multi-Frame Motion Estimation Based on Single Pixel Cameras

    Directory of Open Access Journals (Sweden)

    Sheng Bi

    2016-03-01

    Full Text Available Compressive sensing (CS theory has opened up new paths for the development of signal processing applications. Based on this theory, a novel single pixel camera architecture has been introduced to overcome the current limitations and challenges of traditional focal plane arrays. However, video quality based on this method is limited by existing acquisition and recovery methods, and the method also suffers from being time-consuming. In this paper, a multi-frame motion estimation algorithm is proposed in CS video to enhance the video quality. The proposed algorithm uses multiple frames to implement motion estimation. Experimental results show that using multi-frame motion estimation can improve the quality of recovered videos. To further reduce the motion estimation time, a block match algorithm is used to process motion estimation. Experiments demonstrate that using the block match algorithm can reduce motion estimation time by 30%.

  2. Calibration of gamma camera systems for a multicentre European {sup 123}I-FP-CIT SPECT normal database

    Energy Technology Data Exchange (ETDEWEB)

    Tossici-Bolt, Livia [Southampton Univ. Hospitals NHS Trust, Dept. of Medical Physics and Bioengineering, Southampton (United Kingdom); Dickson, John C. [UCLH NHS Foundation Trust and Univ. College London, Institute of Nuclear Medicine, London (United Kingdom); Sera, Terez [Univ. of Szeged, Dept. of Nuclear Medicine and Euromedic Szeged, Szeged (Hungary); Nijs, Robin de [Rigshospitalet and Univ. of Copenhagen, Neurobiology Research Unit, Copenhagen (Denmark); Bagnara, Maria Claudia [Az. Ospedaliera Universitaria S. Martino, Medical Physics Unit, Genoa (Italy); Jonsson, Cathrine [Karolinska Univ. Hospital, Dept. of Nuclear Medicine, Medical Physics, Stockholm (Sweden); Scheepers, Egon [Univ. of Amsterdam, Dept. of Nuclear Medicine, Academic Medical Centre, Amsterdam (Netherlands); Zito, Felicia [Fondazione IRCCS Granda, Ospedale Maggiore Policlinico, Dept. of Nuclear Medicine, Milan (Italy); Seese, Anita [Univ. of Leipzig, Dept. of Nuclear Medicine, Leipzig (Germany); Koulibaly, Pierre Malick [Univ. of Nice-Sophia Antipolis, Nuclear Medicine Dept., Centre Antoine Lacassagne, Nice (France); Kapucu, Ozlem L. [Gazi Univ., Faculty of Medicine, Dept. of Nuclear Medicine, Ankara (Turkey); Koole, Michel [Univ. Hospital and K.U. Leuven, Nuclear Medicine, Leuven (Belgium); Raith, Maria [Medical Univ. of Vienna, Dept. of Nuclear Medicine, Vienna (Austria); George, Jean [Univ. Catholique Louvain, Nuclear Medicine Division, Mont-Godinne Medical Center, Mont-Godinne (Belgium); Lonsdale, Markus Nowak [Bispebjerg Univ. Hospital, Dept. of Clinical Physiology and Nuclear Medicine, Copenhagen (Denmark); Muenzing, Wolfgang [Univ. of Munich, Dept. of Nuclear Medicine, Munich (Germany); Tatsch, Klaus [Univ. of Munich, Dept. of Nuclear Medicine, Munich (Germany); Municipal Hospital of Karlsruhe Inc., Dept. of Nuclear Medicine, Karlsruhe (Germany); Varrone, Andrea [Center for Psychiatric Research, Karolinska Inst., Dept. of Clinical Neuroscience, Stockholm (Sweden)

    2011-08-15

    A joint initiative of the European Association of Nuclear Medicine (EANM) Neuroimaging Committee and EANM Research Ltd. aimed to generate a European database of [{sup 123}I]FP-CIT single photon emission computed tomography (SPECT) scans of healthy controls. This study describes the characterization and harmonization of the imaging equipment of the institutions involved. {sup 123}I SPECT images of a striatal phantom filled with striatal to background ratios between 10:1 and 1:1 were acquired on all the gamma cameras with absolute ratios measured from aliquots. The images were reconstructed by a core lab using ordered subset expectation maximization (OSEM) without corrections (NC), with attenuation correction only (AC) and additional scatter and septal penetration correction (ACSC) using the triple energy window method. A quantitative parameter, the simulated specific binding ratio (sSBR), was measured using the ''Southampton'' methodology that accounts for the partial volume effect and compared against the actual values obtained from the aliquots. Camera-specific recovery coefficients were derived from linear regression and the error of the measurements was evaluated using the coefficient of variation (COV). The relationship between measured and actual sSBRs was linear across all systems. Variability was observed between different manufacturers and, to a lesser extent, between cameras of the same type. The NC and AC measurements were found to underestimate systematically the actual sSBRs, while the ACSC measurements resulted in recovery coefficients close to 100% for all cameras (AC range 69-89%, ACSC range 87-116%). The COV improved from 46% (NC) to 32% (AC) and to 14% (ACSC) (p < 0.001). A satisfactory linear response was observed across all cameras. Quantitative measurements depend upon the characteristics of the SPECT systems and their calibration is a necessary prerequisite for data pooling. Together with accounting for partial volume, the

  3. A comparison of region-based and pixel-based CEUS kinetics parameters in the assessment of arthritis

    Science.gov (United States)

    Grisan, E.; Raffeiner, B.; Coran, A.; Rizzo, G.; Ciprian, L.; Stramare, R.

    2014-03-01

    Inflammatory rheumatic diseases are leading causes of disability and constitute a frequent medical disorder, leading to inability to work, high comorbidity and increased mortality. The gold-standard for diagnosing and differentiating arthritis is based on patient conditions and radiographic findings, as joint erosions or decalcification. However, early signs of arthritis are joint effusion, hypervascularization and synovial hypertrophy. In particular, vascularization has been shown to correlate with arthritis' destructive behavior, more than clinical assessment. Contrast Enhanced Ultrasound (CEUS) examination of the small joints is emerging as a sensitive tool for assessing vascularization and disease activity. The evaluation of perfusion pattern rely on subjective semi-quantitative scales, that are able to capture the macroscopic degree of vascularization, but are unable to detect the subtler differences in kinetics perfusion parameters that might lead to a deeper understanding of disease progression and a better management of patients. Quantitative assessment is mostly performed by means of the Qontrast software package, that requires the user to define a region of interest, whose mean intensity curve is fitted with an exponential function. We show that using a more physiologically motivated perfusion curve, and by estimating the kinetics parameters separately pixel per pixel, the quantitative information gathered is able to differentiate more effectively different perfusion patterns. In particular, we will show that a pixel-based analysis is able to provide significant markers differentiating rheumatoid arthritis from simil-rheumatoid psoriatic arthritis, that have non-significant differences in clinical evaluation (DAS28), serological markers, or region-based parameters.

  4. No-reference pixel based video quality assessment for HEVC decoded video

    DEFF Research Database (Denmark)

    Huang, Xin; Søgaard, Jacob; Forchhammer, Søren

    2017-01-01

    This paper proposes a No-Reference (NR) Video Quality Assessment (VQA) method for videos subject to the distortion given by the High Efficiency Video Coding (HEVC) scheme. The assessment is performed without access to the bitstream. The proposed analysis is based on the transform coefficients...... estimated from the decoded video pixels, which is used to estimate the level of quantization. The information from this analysis is exploited to assess the video quality. HEVC transform coefficients are modeled with a joint-Cauchy probability density function in the proposed method. To generate VQA features...... at different bitrates and spanning a wide range of content. The results show that the quality scores computed by the proposed method are highly correlated with the mean subjective assessments. (C) 2017 Elsevier Inc. All rights reserved....

  5. Neutron imaging detector based on the muPIC micro-pixel chamber

    CERN Document Server

    Parker, J D; Fujioka, H; Harada, M; Iwaki, S; Kabuki, S; Kishimoto, Y; Kubo, H; Kurosawa, S; Miuchi, K; Nagae, T; Nishimura, H; Oku, T; Sawano, T; Shinohara, T; Suzuki, J; Takada, A; Tanimori, T; Ueno, K

    2012-01-01

    We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349 +/- 36 microns was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10^-12 or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6 microseconds.

  6. An Image Encryption Algorithm Based on Balanced Pixel and Chaotic Map

    Directory of Open Access Journals (Sweden)

    Jian Zhang

    2014-01-01

    Full Text Available Image encryption technology has been applied in many fields and is becoming the main way of protecting the image information security. There are also many ways of image encryption. However, the existing encryption algorithms, in order to obtain a better effect of encryption, always need encrypting several times. There is not an effective method to decide the number of encryption times, generally determined by the human eyes. The paper proposes an image encryption algorithm based on chaos and simultaneously proposes a balanced pixel algorithm to determine the times of image encryption. Many simulation experiments have been done including encryption effect and security analysis. Experimental results show that the proposed method is feasible and effective.

  7. Pixel Intensity Based Cumulative Features for Moving Object Tracking (MOT) in Darkness

    Science.gov (United States)

    Saba, Tanzila

    2016-06-01

    Moving Object Tracking (MOT) is one of the frequent used tasks in computer vision systems and on the same time a challenging issue particularly in darkness. Vehicle tracking involves finding new position of vehicles in consecutive frames. This paper presents MOT algorithm that is developed for advanced driver safety applications like automatic high beam control, forward collision warning. Accordingly, the proposed approach targets vehicle tracking in the dark environment. Hence, a camera is mounted on the host vehicle to capture video frames of the traffic ahead. The scope involves tracking of both oncoming and preceding vehicles. The vehicles are tracked in consecutive frames using grayscale information and robust structure features. The features representation of the vehicle region is based on cumulative pixel intensity information. The implementation for feature extraction is optimized by using a dynamic programming approach to meet the constraints of a real time application. Simulation results thus obtained are promising in state of the art.

  8. 直线生成的像素行算法%Straight line generation algorithm based on pixel line

    Institute of Scientific and Technical Information of China (English)

    厉玉蓉; 董付国; 刘岩; 牛翠霞

    2011-01-01

    On the basis of Bresenham algorithm and other fast algorithms based on multi-pixel incremental generation method, we proposes and implements a new algorithm based on pixel line, considering that the increment between adjacent pixels is determined by the line slope. We take full advantage of the relativity between pixels in the same line, generating all pixels in a pixel line once. The new algorithm guarantees the same line precision as the Bresenham algorithm, using only integer operation and shift operations, which can give a higher speed and can easily be implemented in hardware. The smaller the angle between the line and the coordination axis is, the more efficiency this algorithm can obtain. This algorithm based on pixel line is of great significance.%在Bresenham算法基础上,采用多点画线法的思想,设计并实现了直线快速生成的像素行算法.根据相邻像素之间的增量取决于直线斜率这一特点,该算法一次生成一个像素行中所有像素点坐标.算法分析与大量实验结果均表明,在保证直线精确度与Bresenham算法相同的情况下,像素行算法减少了大量计算,提高了直线生成效率,直线与x或y坐标轴夹角α越小,算法速度就越快,提高倍数接近于1/tanα,具有较大的理论价值和实际意义.

  9. EGS5 simulations to design a Ce:GAGG scintillator based Compton camera.

    Science.gov (United States)

    Malik, Azhar H; Shimazoe, Kenji; Takahashi, Hiroyuki

    2013-01-01

    Ce(+3): Gd3Al2Ga3O12 (Ce:GAGG) is expected to be promising scintillator for PET, SPECT, and gamma camera applications because of its attractive properties. We designed a Compton camera based on Ce:GAGG, both as scatterer and absorber, for imaging and radioactivity measurement of point sources. The two important parameters sensitivity and spatial resolution are determined for 4 × 4 pixels, each pixel of size 1 × 1 cm(2), for both scatterer and absorber. Our main focus in this paper is to image a distant source for which sensitivity is of prime importance. High sensitivity and light weight are two important advantages of Compton camera for distant source imaging and the availability of Ce:GAGG 3 × 3 mm(2) pixel size is expected to give a spatial resolution of ~ 5 mm for medical applications as well.

  10. Development and characterization of high-resolution neutron pixel detectors based on Timepix read-out chips

    Science.gov (United States)

    Krejci, F.; Zemlicka, J.; Jakubek, J.; Dudak, J.; Vavrik, D.; Köster, U.; Atkins, D.; Kaestner, A.; Soltes, J.; Viererbl, L.; Vacik, J.; Tomandl, I.

    2016-12-01

    Using a suitable isotope such as 6Li and 10B semiconductor hybrid pixel detectors can be successfully adapted for position sensitive detection of thermal and cold neutrons via conversion into energetic light ions. The adapted devices then typically provides spatial resolution at the level comparable to the pixel pitch (55 μm) and sensitive area of about few cm2. In this contribution, we describe further progress in neutron imaging performance based on the development of a large-area hybrid pixel detector providing practically continuous neutron sensitive area of 71 × 57 mm2. The measurements characterising the detector performance at the cold neutron imaging instrument ICON at PSI and high-flux imaging beam-line Neutrograph at ILL are presented. At both facilities, high-resolution high-contrast neutron radiography with the newly developed detector has been successfully applied for objects which imaging were previously difficult with hybrid pixel technology (such as various composite materials, objects of cultural heritage etc.). Further, a significant improvement in the spatial resolution of neutron radiography with hybrid semiconductor pixel detector based on the fast read-out Timepix-based detector is presented. The system is equipped with a thin planar 6LiF convertor operated effectively in the event-by-event mode enabling position sensitive detection with spatial resolution better than 10 μm.

  11. Characterization of the column-based priority logic readout of Topmetal-II‑ CMOS pixel direct charge sensor

    Science.gov (United States)

    An, M.; Zhang, W.; Xiao, L.; Gao, C.; Chen, C.; Han, M.; Huang, G.; Ji, R.; Li, X.; Liu, J.; Mei, Y.; Pei, H.; Sun, Q.; Sun, X.; Wang, K.; Yang, P.; Zhou, W.

    2017-03-01

    We present the detailed study of the digital readout of Topmetal-II- CMOS pixel direct charge sensor. Topmetal-II- is an integrated sensor with an array of 72×72 pixels each capable of directly collecting external charge through exposed metal electrodes in the topmost metal layer. In addition to the time-shared multiplexing readout of the analog output from Charge Sensitive Amplifiers in each pixel, hits are also generated through comparators in each pixel with individually adjustable thresholds. The hits are read out via a column-based priority logic structure, retaining both hit location and time information. The in-array column-based priority logic features with a full clock-less circuitry hence there is no continuously running clock distributed in the pixel and matrix logic. These characteristics enable its use as the charge readout device in future Time Projection Chambers without gaseous gain mechanism, which has unique advantages in low background and low rate-density experiments. We studied the detailed working behavior and performance of this readout, and demonstrated its functional validity and potential in imaging applications.

  12. NOTE: First images of a digital autoradiography system based on a Medipix2 hybrid silicon pixel detector

    Science.gov (United States)

    Mettivier, Giovanni; Montesi, Maria Cristina; Russo, Paolo

    2003-06-01

    We present the first images of beta autoradiography obtained with the high-resolution hybrid pixel detector consisting of the Medipix2 single photon counting read-out chip bump-bonded to a 300 µm thick silicon pixel detector. This room temperature system has 256 × 256 square pixels of 55 µm pitch (total sensitive area of 14 × 14 mm2), with a double threshold discriminator and a 13-bit counter in each pixel. It is read out via a dedicated electronic interface and control software, also developed in the framework of the European Medipix2 Collaboration. Digital beta autoradiograms of 14C microscale standard strips (containing separate bands of increasing specific activity in the range 0.0038-32.9 kBq g-1) indicate system linearity down to a total background noise of 1.8 × 10-3 counts mm-2 s-1. The minimum detectable activity is estimated to be 0.012 Bq for 36 000 s exposure and 0.023 Bq for 10 800 s exposure. The measured minimum detection threshold is less than 1600 electrons (equivalent to about 6 keV Si). This real-time system for beta autoradiography offers lower pixel pitch and higher sensitive area than the previous Medipix1-based system. It has a 14C sensitivity better than that of micro channel plate based systems, which, however, shows higher spatial resolution and sensitive area.

  13. On scalable lossless video coding based on sub-pixel accurate MCTF

    Science.gov (United States)

    Yea, Sehoon; Pearlman, William A.

    2006-01-01

    We propose two approaches to scalable lossless coding of motion video. They achieve SNR-scalable bitstream up to lossless reconstruction based upon the subpixel-accurate MCTF-based wavelet video coding. The first approach is based upon a two-stage encoding strategy where a lossy reconstruction layer is augmented by a following residual layer in order to obtain (nearly) lossless reconstruction. The key advantages of our approach include an 'on-the-fly' determination of bit budget distribution between the lossy and the residual layers, freedom to use almost any progressive lossy video coding scheme as the first layer and an added feature of near-lossless compression. The second approach capitalizes on the fact that we can maintain the invertibility of MCTF with an arbitrary sub-pixel accuracy even in the presence of an extra truncation step for lossless reconstruction thanks to the lifting implementation. Experimental results show that the proposed schemes achieve compression ratios not obtainable by intra-frame coders such as Motion JPEG-2000 thanks to their inter-frame coding nature. Also they are shown to outperform the state-of-the-art non-scalable inter-frame coder H.264 (JM) lossless mode, with the added benefit of bitstream embeddedness.

  14. A noiseless kilohertz frame rate imaging detector based on microchannel plates read out with the Medipix2 CMOS pixel chip

    CERN Document Server

    Mikulec, Bettina; Ferrère, Didier; La Marra, Daniel; McPhate, J B; Tremsin, A S; Siegmund, O H W; Vallerga, J V; Clement, J; Ponchut, C; Rigal, J M; CERN. Geneva

    2006-01-01

    A new hybrid optical imaging detector is described that is being developed for the next generation adaptive optics (AO) wavefront sensors (WFS) for ground-based telescopes. The detector consists of a photocathode and proximity focused microchannel plates (MCPs) read out by the Medipix2 CMOS pixel ASIC. Each pixel of the Medipix2 device measures 55x55 um2 and comprises pre-amplifier, a window discriminator and a 14-bit counter. The 256x256 Medipix2 array can be read out noiselessly in 287 us. The readout can be electronically shuttered down to a temporal window of a few us. The Medipix2 is buttable on 3 sides to produce 512x(n*256) pixel devices. Measurements with ultraviolet light yield a spatial resolution of the detector at the Nyquist limit. Sub-pixel resolution can be achieved using centroiding algorithms. For the AO application, very high continuous frame rates of the order of 1 kHz are required for a matrix of 512x512 pixels. The design concepts of a parallel readout board are presented that will allow ...

  15. Full-Color Computational Imaging with Single-Pixel Detectors Based on a 2D Discrete Cosine Transform

    CERN Document Server

    Liu, Bao-Lei; Wu, Ling-An

    2016-01-01

    We propose and demonstrate a computational imaging technique that uses structured illumination based on a two-dimensional discrete cosine transform to perform imaging with a single-pixel detector. A scene is illuminated by a projector with two sets of orthogonal patterns, then by applying an inverse cosine transform to the spectra obtained from the single-pixel detector a full-color image is retrieved. This technique can retrieve an image from sub-Nyquist measurements, and the background noise is easily canceled to give excellent image quality. Moreover, the experimental setup is very simple.

  16. Component temperatures inversion for remote sensing pixel based on directional thermal radiation model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    When the remote sensing pixel is composed of multiple components and a non-isothermal surface,its directional signature of thermal-infrared radiation is mainly determined by the 3D structure of the pixel.In this paper,we present our simple directional thermal radiation model to describe the relation between the pixel thermal emission and the pixel's component parameters,and invert the model to get the component temperatures.For the inversion algorithm,we focus on how to use the information of given observations in a more effective way.The information content in data space and parameter space is defined,and the transferring of information content in inversion procedure is studied.Our forward model and inversion method are validated using indoor directional measurement data.

  17. Uncertainties in pixel-based source reconstruction for gravitationally lensed objects and applications to lensed galaxies

    Science.gov (United States)

    Tagore, Amitpal Singh

    Gravitational lens modeling of spatially resolved sources is a challenging inverse problem that can involve many observational constraints and model parameters. I present a new software package, pixsrc, that works in conjunction with the lensmodel software and builds on established pixel-based source reconstruction (PBSR) algorithms for de-lensing a source and constraining lens model parameters. Using test data, I explore statistical and systematic uncertainties associated with gridding, source regularization, interpolation errors, noise, and telescope pointing. I compare two gridding schemes in the source plane: a fully adaptive grid and an adaptive Cartesian grid. I also consider regularization schemes that minimize derivatives of the source and introduce a scheme that minimizes deviations from an analytic source profile. Careful choice of gridding and regularization can reduce "discreteness noise" in the chi2 surface that is inherent in the pixel-based methodology. With a gridded source, errors due to interpolation need to be taken into account (especially for high S/N data). Different realizations of noise and telescope pointing lead to slightly different values for lens model parameters, and the scatter between different "observations" can be comparable to or larger than the model uncertainties themselves. The same effects create scatter in the lensing magnification at the level of a few percent for a peak S/N of 10. I then apply pixsrc to observations of lensed, high-redshift galaxies. SDSS J0901+1814, is an ultraluminous infrared galaxy at z=2.26 that is also UV-bright, and it is lensed by a foreground group of galaxies at z=0.35. I constrain the lens model using maps of CO(3-2) rotational line emission and optical imaging and apply the lens model to observations of CO(1-0), H-alpha, and [NII] line emission as well. Using the de-lensed images, I calculate properties of the source, such as the gas mass fraction and dynamical mass. Finally, I examine a

  18. Spectral-spatial hyperspectral image classification using super-pixel-based spatial pyramid representation

    Science.gov (United States)

    Fan, Jiayuan; Tan, Hui Li; Toomik, Maria; Lu, Shijian

    2016-10-01

    Spatial pyramid matching has demonstrated its power for image recognition task by pooling features from spatially increasingly fine sub-regions. Motivated by the concept of feature pooling at multiple pyramid levels, we propose a novel spectral-spatial hyperspectral image classification approach using superpixel-based spatial pyramid representation. This technique first generates multiple superpixel maps by decreasing the superpixel number gradually along with the increased spatial regions for labelled samples. By using every superpixel map, sparse representation of pixels within every spatial region is then computed through local max pooling. Finally, features learned from training samples are aggregated and trained by a support vector machine (SVM) classifier. The proposed spectral-spatial hyperspectral image classification technique has been evaluated on two public hyperspectral datasets, including the Indian Pines image containing 16 different agricultural scene categories with a 20m resolution acquired by AVIRIS and the University of Pavia image containing 9 land-use categories with a 1.3m spatial resolution acquired by the ROSIS-03 sensor. Experimental results show significantly improved performance compared with the state-of-the-art works. The major contributions of this proposed technique include (1) a new spectral-spatial classification approach to generate feature representation for hyperspectral image, (2) a complementary yet effective feature pooling approach, i.e. the superpixel-based spatial pyramid representation that is used for the spatial correlation study, (3) evaluation on two public hyperspectral image datasets with superior image classification performance.

  19. Memory based active contour algorithm using pixel-level classified images for colon crypt segmentation.

    Science.gov (United States)

    Cohen, Assaf; Rivlin, Ehud; Shimshoni, Ilan; Sabo, Edmond

    2015-07-01

    In this paper, we introduce a novel method for detection and segmentation of crypts in colon biopsies. Most of the approaches proposed in the literature try to segment the crypts using only the biopsy image without understanding the meaning of each pixel. The proposed method differs in that we segment the crypts using an automatically generated pixel-level classification image of the original biopsy image and handle the artifacts due to the sectioning process and variance in color, shape and size of the crypts. The biopsy image pixels are classified to nuclei, immune system, lumen, cytoplasm, stroma and goblet cells. The crypts are then segmented using a novel active contour approach, where the external force is determined by the semantics of each pixel and the model of the crypt. The active contour is applied for every lumen candidate detected using the pixel-level classification. Finally, a false positive crypt elimination process is performed to remove segmentation errors. This is done by measuring their adherence to the crypt model using the pixel level classification results. The method was tested on 54 biopsy images containing 4944 healthy and 2236 cancerous crypts, resulting in 87% detection of the crypts with 9% of false positive segments (segments that do not represent a crypt). The segmentation accuracy of the true positive segments is 96%.

  20. Efficient reversible watermarking based on adaptive prediction-error expansion and pixel selection.

    Science.gov (United States)

    Li, Xiaolong; Yang, Bin; Zeng, Tieyong

    2011-12-01

    Prediction-error expansion (PEE) is an important technique of reversible watermarking which can embed large payloads into digital images with low distortion. In this paper, the PEE technique is further investigated and an efficient reversible watermarking scheme is proposed, by incorporating in PEE two new strategies, namely, adaptive embedding and pixel selection. Unlike conventional PEE which embeds data uniformly, we propose to adaptively embed 1 or 2 bits into expandable pixel according to the local complexity. This avoids expanding pixels with large prediction-errors, and thus, it reduces embedding impact by decreasing the maximum modification to pixel values. Meanwhile, adaptive PEE allows very large payload in a single embedding pass, and it improves the capacity limit of conventional PEE. We also propose to select pixels of smooth area for data embedding and leave rough pixels unchanged. In this way, compared with conventional PEE, a more sharply distributed prediction-error histogram is obtained and a better visual quality of watermarked image is observed. With these improvements, our method outperforms conventional PEE. Its superiority over other state-of-the-art methods is also demonstrated experimentally.

  1. Synchrotron beam test of a photon counting pixel prototype based on Double-SOI technology

    Science.gov (United States)

    Zhou, Y.; Lu, Y.; Hashimoto, R.; Nishimura, R.; Kishimoto, S.; Arai, Y.; Ouyang, Q.

    2017-01-01

    The overall noise performances and first synchrotron beam measurement results of CPIXETEG3b, the first counting type Silicon-On-Insulator (SOI) pixel sensor prototype without crosstalk issue, are reported. The prototype includes a 64 × 64 pixel matrix with 50 μm pitch size. Each pixel consists of an N-in-P charge collection diode, a charge sensitive preamplifier, a shaper, a discriminator with thresholds adjustable by an in-pixel 4-bit DAC, and a 6-bit counter. The study was performed using the beam line 14A at KEK Photon Factory (KEK-PF) . The homogeneous response of the prototype, including charging-sharing effects between pixels were studied. 16 keV and 8 keV monochromatic small size (~ 10 μm diameter) X-ray beams were used for the charge sharing study, and a flat-field was added for homogenous response investigation. The overall detector homogeneity and the influence of basic detector parameters on charge sharing between pixels has been investigated.

  2. Development of the set of corrections for a gamma camera dedicated to research; Desarrollo del conjunto de correcciones para una gammacamara dedicada a investigacion

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez Insua, M.; Ambroa Rey, E. M.; Vazquez Vazquez, R.; Sanchez Garcia, M.; Luna Vega, V.; Mosquera Sueiro, J.; Otero Martinez, C.; Lobato Busto, R.; Pombar Camean, M.

    2013-07-01

    As part of a project for animal research, replaced electronics one of the gamma-cameras (GC) of the service that was out of use, with the aim of using it for SPECT. The implementation is therefore required of the corrections that allow image quality enough for SPECT from raw data supplied by the team. This has been developed software that enables to perform correction of power, uniform and linearity on the acquired data. For validation, change in several parameters indicative of the image quality has been evaluated. (Author)

  3. 3D reconstructions with pixel-based images are made possible by digitally clearing plant and animal tissue

    Science.gov (United States)

    Reconstruction of 3D images from a series of 2D images has been restricted by the limited capacity to decrease the opacity of surrounding tissue. Commercial software that allows color-keying and manipulation of 2D images in true 3D space allowed us to produce 3D reconstructions from pixel based imag...

  4. Dual-mode optical microscope based on single-pixel imaging

    Science.gov (United States)

    Rodríguez, A. D.; Clemente, P.; Tajahuerce, E.; Lancis, J.

    2016-07-01

    We demonstrate an inverted microscope that can image specimens in both reflection and transmission modes simultaneously with a single light source. The microscope utilizes a digital micromirror device (DMD) for patterned illumination altogether with two single-pixel photosensors for efficient light detection. The system, a scan-less device with no moving parts, works by sequential projection of a set of binary intensity patterns onto the sample that are codified onto a modified commercial DMD. Data to be displayed are geometrically transformed before written into a memory cell to cancel optical artifacts coming from the diamond-like shaped structure of the micromirror array. The 24-bit color depth of the display is fully exploited to increase the frame rate by a factor of 24, which makes the technique practicable for real samples. Our commercial DMD-based LED-illumination is cost effective and can be easily coupled as an add-on module for already existing inverted microscopes. The reflection and transmission information provided by our dual microscope complement each other and can be useful for imaging non-uniform samples and to prevent self-shadowing effects.

  5. Multi-Scale Pixel-Based Image Fusion Using Multivariate Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    Naveed ur Rehman

    2015-05-01

    Full Text Available A novel scheme to perform the fusion of multiple images using the multivariate empirical mode decomposition (MEMD algorithm is proposed. Standard multi-scale fusion techniques make a priori assumptions regarding input data, whereas standard univariate empirical mode decomposition (EMD-based fusion techniques suffer from inherent mode mixing and mode misalignment issues, characterized respectively by either a single intrinsic mode function (IMF containing multiple scales or the same indexed IMFs corresponding to multiple input images carrying different frequency information. We show that MEMD overcomes these problems by being fully data adaptive and by aligning common frequency scales from multiple channels, thus enabling their comparison at a pixel level and subsequent fusion at multiple data scales. We then demonstrate the potential of the proposed scheme on a large dataset of real-world multi-exposure and multi-focus images and compare the results against those obtained from standard fusion algorithms, including the principal component analysis (PCA, discrete wavelet transform (DWT and non-subsampled contourlet transform (NCT. A variety of image fusion quality measures are employed for the objective evaluation of the proposed method. We also report the results of a hypothesis testing approach on our large image dataset to identify statistically-significant performance differences.

  6. A Statistical Definition of Image Resolution Based on the Correlation of Pixels

    CERN Document Server

    Zhou, Jian-Feng

    2015-01-01

    Resolution, usually defined by the Rayleigh criterion or the Full Width at Half Maximum of a Point Spread Function, is a basic property of an image. Here, we present a new statistical definition of image resolution based on the cross-correlation properties of the pixels in an image. It is shown that the new definition of image resolution depends not only on the PSF of an imaging device, but also on the signal-to-noise ratio of the data and on the structures of an object. In an image, the resolution does not have to be uniform. Our new definition is also suitable for the interpretation of the result of a deconvolution. We illustrate this, in this paper, with a Wiener deconvolution. It is found that weak structures can be extracted from low signal-to-noise ratio data, but with low resolution; a high-resolution image was obtained from high signal-to-noise ratio data after a Wiener deconvolution. The new definition can also be used to compare various deconvolution algorithms on their processing effects, such as r...

  7. Neutron imaging detector based on the {mu}PIC micro-pixel chamber

    Energy Technology Data Exchange (ETDEWEB)

    Parker, J.D., E-mail: jparker@cr.scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Hattori, K.; Fujioka, H. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Harada, M. [Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Iwaki, S.; Kabuki, S.; Kishimoto, Y.; Kubo, H.; Kurosawa, S.; Miuchi, K.; Nagae, T.; Nishimura, H. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Oku, T. [Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Sawano, T. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Shinohara, T.; Suzuki, J. [Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Takada, A.; Tanimori, T.; Ueno, K. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan)

    2013-01-01

    We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber ({mu}PIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10 Multiplication-Sign 10 cm{sup 2} and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and three-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349{+-}36{mu}m was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10{sup -12} or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6{mu}s.

  8. From pixels to patches: a cloud classification method based on bag of micro-structures

    Directory of Open Access Journals (Sweden)

    Q. Li

    2015-10-01

    Full Text Available Automatic cloud classification has attracted more and more attention with the increasing development of whole sky imagers, but it is still in progress for ground-based cloud observation. This paper proposes a new cloud classification method, named bag of micro-structures (BoMS. This method treats an all-sky image as a collection of micro-structures mapped from image patches, rather than a collection of pixels. And then it constructs an image representation with a weighted histogram of micro-structures. Lastly, a support vector machine (SVM classifier is applied on the image representation because SVM is appealing for sparse and high dimensional feature space. Five different sky conditions are identified: cirriform, cumuliform, stratiform, clear sky and mixed cloudiness that often appears in all-sky images but is seldom addressed in literature. BoMS is evaluated on a large dataset, which contains 5000 all-sky images that are captured by a total-sky cloud imager located in Tibet (29.25° N, 88.88° E. BoMS achieves an accuracy of 90.9 % for 10 fold cross-validation, and it outperforms the state-of-the-art method with an increase of about 19 %. Furthermore, influence of key parameters in BoMS are investigated to verify their robustness.

  9. A Sub-pixel Image Processing Algorithm of a Detector Based on Staring Focal Plane Array

    Institute of Scientific and Technical Information of China (English)

    LI Ya-qiong; JIN Wei-qi; XU Chao; WANG Xia

    2008-01-01

    Optical micro-scanning technology can be used to increase spatial resolution of many optical imaging systems, especially thermal imaging system. One of its key issues is relevant image processing algorithm. A fast reconstruction algo-rithm is proposed for two dimensional 2×2 micro-scanning based on the sub-pixel imaging and reconstruction principle of two-dimensional stating focal plane arrays (FPA). Specifically, three initialization methods are presented and implemented with the simulated data, their performances are compared according to image quality index . Experiment results show that, by the first initialization approach, tirnely over-sampled image can be accurately recovered, although special field diaphragm is needed. In the second initialization, the extrapolation approximation in obtaining reconstruction results is better than either bilinear interpolation or over-sampling reconstruction, without requiting any special process on system. The proposed algorithm has simple structure, low computational cost and can be realized in real-time. A high-resolution image can be obtained by low-resolution detectors. So, the algorithm has potential applications in visible light and infrared imaging area.

  10. Parcels versus pixels: modeling agricultural land use across broad geographic regions using parcel-based field boundaries

    Science.gov (United States)

    Sohl, Terry L.; Dornbierer, Jordan; Wika, Steve; Sayler, Kristi L.; Quenzer, Robert

    2017-01-01

    Land use and land cover (LULC) change occurs at a local level within contiguous ownership and management units (parcels), yet LULC models primarily use pixel-based spatial frameworks. The few parcel-based models being used overwhelmingly focus on small geographic areas, limiting the ability to assess LULC change impacts at regional to national scales. We developed a modified version of the Forecasting Scenarios of land use change model to project parcel-based agricultural change across a large region in the United States Great Plains. A scenario representing an agricultural biofuel scenario was modeled from 2012 to 2030, using real parcel boundaries based on contiguous ownership and land management units. The resulting LULC projection provides a vastly improved representation of landscape pattern over existing pixel-based models, while simultaneously providing an unprecedented combination of thematic detail and broad geographic extent. The conceptual approach is practical and scalable, with potential use for national-scale projections.

  11. Dealing with heterogeneous landslide information for landslide susceptibility assessment: comparing a pixel-based and slope unit-based approach

    Science.gov (United States)

    Jacobs, Liesbet; Kervyn, Matthieu; Poesen, Jean; Reichenbach, Paola; Rossi, Mauro; Marchesini, Ivan; Alvioli, Massimiliano; Dewitte, Olivier

    2017-04-01

    In the Rwenzori Mountains, various multi-disciplinary data collection initiatives have resulted in a heterogeneous database counting 247 fully characterized landslides with known size and shape (polygon dataset) and 307 landslides represented as single points taken at an unknown location within the landslide body (point dataset). While the polygon dataset covers only 9% of the inhabited highlands, the point dataset extends the total inventoried area to 18% of the entire inhabited highland region. A regional susceptibility model for the total area should therefore include both information from polygon- as well as point datasets. This involves two distinct methodological challenges with regard to the use of points and polygons respectively. Firstly, the point dataset, where the location of the point within the landslide body is unknown, may not be fully representative for the spatial conditions under which the landslides occurred. Here we aim to identify a robust approach, to limit this uncertainty and maximize the point location representativeness. For this purpose, a pixel-based approach is tested and compared to a slope unit-based approach. To mimic the uncertainty related to the localization of the points, 50 random samplings of single points within each landslide were performed and then fed into a logistic regression model. The model was thus run 50 times using both the slope unit-based and the pixel-based approach. The results show that the slope unit-based alternative has an overall better performance than the pixel-based with comparable stability over the runs. Based on these results, the slope unit seems a more appropriate mapping unit for a susceptibility model based on point-data. A second significant methodological issue, when using polygon-based models, concerns the decision on when a slope unit is considered to be landslide-prone. A threshold representing the fraction of the slope unit affected by landslides above which a slope unit is assigned to be

  12. Component temperatures inversion for remote sensing pixel based on directional thermal radiation model

    Institute of Scientific and Technical Information of China (English)

    王锦地; 李小文; 孙晓敏; 刘强

    2000-01-01

    When the remote sensing pixel is composed of multiple components and a non-isothermal surface, its directional signature of thermal-infrared radiation is mainly determined by the 3D structure of the pixel. In this paper, we present our simple directional thermal radiation model to describe the relation between the pixel thermal emission and the pixel’s component parameters, and invert the model to get the component temperatures. For the inversion algorithm, we focus on how to use the information of given observations in a more effective way. The information content in data space and parameter space is defined, and the transferring of information content in inversion procedure is studied. Our forward model and inversion method are validated using indoor directional measurement data.

  13. The added value of a portable gamma camera for intraoperative detection of sentinel lymph node in squamous cell carcinoma of the oral cavity: A case report.

    Science.gov (United States)

    Mayoral, M; Paredes, P; Sieira, R; Vidal-Sicart, S; Marti, C; Pons, F

    2014-01-01

    The use of sentinel lymph node biopsy in squamous cell carcinoma of the oral cavity is still subject to debate although some studies have reported its feasibility. The main reason for this debate is probably due to the high false-negative rate for floor-of-mouth tumors per se. We report the case of a 54-year-old man with a T1N0 floor-of-mouth squamous cell carcinoma who underwent the sentinel lymph node procedure. Lymphoscintigraphy and SPECT/CT imaging were performed for lymphatic mapping with a conventional gamma camera. Sentinel lymph nodes were identified at right Ib, left IIa and Ia levels. However, these sentinel lymph nodes were difficult to detect intraoperatively with a gamma probe owing to the activity originating from the injection site. The use of a portable gamma camera made it possible to localize and excise all the sentinel lymph nodes. This case demonstrates the usefulness of this tool to improve sentinel lymph node detecting in floor-of-mouth tumors, especially those close to the injection area. Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.

  14. Imaging properties of small-pixel spectroscopic x-ray detectors based on cadmium telluride sensors.

    Science.gov (United States)

    Koenig, Thomas; Schulze, Julia; Zuber, Marcus; Rink, Kristian; Butzer, Jochen; Hamann, Elias; Cecilia, Angelica; Zwerger, Andreas; Fauler, Alex; Fiederle, Michael; Oelfke, Uwe

    2012-11-07

    Spectroscopic x-ray imaging by means of photon counting detectors has received growing interest during the past years. Critical to the image quality of such devices is their pixel pitch and the sensor material employed. This paper describes the imaging properties of Medipix2 MXR multi-chip assemblies bump bonded to 1 mm thick CdTe sensors. Two systems were investigated with pixel pitches of 110 and 165 μm, which are in the order of the mean free path lengths of the characteristic x-rays produced in their sensors. Peak widths were found to be almost constant across the energy range of 10 to 60 keV, with values of 2.3 and 2.2 keV (FWHM) for the two pixel pitches. The average number of pixels responding to a single incoming photon are about 1.85 and 1.45 at 60 keV, amounting to detective quantum efficiencies of 0.77 and 0.84 at a spatial frequency of zero. Energy selective CT acquisitions are presented, and the two pixel pitches' abilities to discriminate between iodine and gadolinium contrast agents are examined. It is shown that the choice of the pixel pitch translates into a minimum contrast agent concentration for which material discrimination is still possible. We finally investigate saturation effects at high x-ray fluxes and conclude with the finding that higher maximum count rates come at the cost of a reduced energy resolution.

  15. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  16. Optical image encryption based on binary Fourier transform computer-generated hologram and pixel scrambling technology

    Science.gov (United States)

    Wang, Yong-Ying; Wang, Yu-Rong; Wang, Yong; Li, Hui-Juan; Sun, Wen-Jia

    2007-07-01

    A new method of optical image encryption with binary Fourier transform computer-generated hologram (CGH) and pixel-scrambling technology is presented. In this method, the orders of the pixel scrambling, as well as the encrypted image, are used as the keys to decrypt the original image. Therefore, higher security is achieved. Furthermore, the encrypted image is binary, so it is easy to be fabricated and robust against noise and distortion. Computer simulation results are given to verify the feasibility of this method and its robustness against occlusion and additional noise.

  17. A Pixel Domain Video Coding based on Turbo code and Arithmetic code

    Directory of Open Access Journals (Sweden)

    Cyrine Lahsini

    2012-05-01

    Full Text Available In recent years, with emerging applications such as multimedia sensors networks, wirelesslow-power surveillance and mobile camera phones, the traditional video coding architecture in beingchallenged. In fact, these applications have different requirements than those of the broadcast videodelivery systems: a low power consumption at the encoder side is essential.In this context, we propose a pixel-domain video coding scheme which fits well in these senarios.In this system, both the arithmetic and turbo codes are used to encode the video sequence's frames.Simulations results show significant gains over Pixel-domain Wyner-Ziv video codeingr.

  18. A real-time autostereoscopic display method based on partial sub-pixel by general GPU processing

    Science.gov (United States)

    Chen, Duo; Sang, Xinzhu; Cai, Yuanfa

    2013-08-01

    With the progress of 3D technology, the huge computing capacity for the real-time autostereoscopic display is required. Because of complicated sub-pixel allocating, masks providing arranged sub-pixels are fabricated to reduce real-time computation. However, the binary mask has inherent drawbacks. In order to solve these problems, weighted masks are used in displaying based on partial sub-pixel. Nevertheless, the corresponding computations will be tremendously growing and unbearable for CPU. To improve calculating speed, Graphics Processing Unit (GPU) processing with parallel computing ability is adopted. Here the principle of partial sub-pixel is presented, and the texture array of Direct3D 10 is used to increase the number of computable textures. When dealing with a HD display and multi-viewpoints, a low level GPU is still able to permit a fluent real time displaying, while the performance of high level CPU is really not acceptable. Meanwhile, after using texture array, the performance of D3D10 could be double, and sometimes be triple faster than D3D9. There are several distinguishing features for the proposed method, such as the good portability, less overhead and good stability. The GPU display system could also be used for the future Ultra HD autostereoscopic display.

  19. iPixel: a visual content-based and semantic search engine for retrieving digitized mammograms by using collective intelligence.

    Science.gov (United States)

    Alor-Hernández, Giner; Pérez-Gallardo, Yuliana; Posada-Gómez, Rubén; Cortes-Robles, Guillermo; Rodríguez-González, Alejandro; Aguilar-Laserre, Alberto A

    2012-09-01

    Nowadays, traditional search engines such as Google, Yahoo and Bing facilitate the retrieval of information in the format of images, but the results are not always useful for the users. This is mainly due to two problems: (1) the semantic keywords are not taken into consideration and (2) it is not always possible to establish a query using the image features. This issue has been covered in different domains in order to develop content-based image retrieval (CBIR) systems. The expert community has focussed their attention on the healthcare domain, where a lot of visual information for medical analysis is available. This paper provides a solution called iPixel Visual Search Engine, which involves semantics and content issues in order to search for digitized mammograms. iPixel offers the possibility of retrieving mammogram features using collective intelligence and implementing a CBIR algorithm. Our proposal compares not only features with similar semantic meaning, but also visual features. In this sense, the comparisons are made in different ways: by the number of regions per image, by maximum and minimum size of regions per image and by average intensity level of each region. iPixel Visual Search Engine supports the medical community in differential diagnoses related to the diseases of the breast. The iPixel Visual Search Engine has been validated by experts in the healthcare domain, such as radiologists, in addition to experts in digital image analysis.

  20. Design of a current based readout chip and development of a DEPFET pixel prototype system for the ILC vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Trimpl, M.

    2005-12-15

    The future TeV-scale linear collider ILC (International Linear Collider) offers a large variety of precision measurements complementary to the discovery potential of the LHC (Large Hadron Collider). To fully exploit its physics potential, a vertex detector with unprecedented performance is needed. One proposed technology for the ILC vertex detector is the DEPFET active pixel sensor. The DEPFET sensor offers particle detection with in-pixel amplification by incorporating a field effect transistor into a fully depleted high-ohmic silicon substrate. The device provides an excellent signal-to-noise ratio and a good spatial resolution at the same time. To establish a very fast readout of a DEPFET pixel matrix with row rates of 20 MHz and more, the 128 channel CURO II ASIC has been designed and fabricated. The architecture of the chip is completely based on current mode techniques (SI) perfectly adapted to the current signal of the sensor. For the ILC vertex detector a prototype system with a 64 x 128 DEPFET pixel matrix read out by the CURO II chip has been developed. The design issues and the standalone performance of the readout chip as well as first results with the prototype system will be presented. (orig.)

  1. A kilo-pixel imaging system for future space based far-infrared observatories using microwave kinetic inductance detectors

    CERN Document Server

    Baselmans, J J A; Yates, S J C; Yurduseven, O; Llombart, N; Karatsu, K; Baryshev, A M; Ferrari, L; Endo, A; Thoen, D J; de Visser, P J; Janssen, R M J; Murugesan, V; Driessen, E F C; Coiffard, G; Martin-Pintado, J; Hargrave, P; Griffin, M

    2016-01-01

    Future astrophysics and cosmic microwave background space missions operating in the far-infrared to millimetre part of the spectrum will require very large arrays of ultra-sensitive detectors in combination with high multiplexing factors and efficient low- noise and low-power readout systems. We have developed a demonstrator system suitable for such applications. The system combines a 961 pixel imaging array based upon Microwave Kinetic Inductance Detectors (MKIDs) with a readout system capable of reading out all pixels simultaneously with only one readout cable pair and a single cryogenic amplifier. We evaluate, in a representative environment, the system performance in terms of sensitivity, dynamic range, optical efficiency, cosmic ray rejection, pixel-pixel crosstalk and overall yield at an observation frequency of 850 GHz. The overall system has an excellent sensitivity, with an average detector sensitivity NEP=2.8 +- 0.8 x 10^-19 W/rt(Hz) measured using a thermal calibration source. The dynamic range wou...

  2. Monitoring of the internal contamination of occupationally exposure personnel in services of nuclear medicine through the use of gamma cameras; Monitoreo de la contaminacion interna de personal ocupacionalmente expuesto en servicios de medicina nuclear mediante el uso de gamma camaras

    Energy Technology Data Exchange (ETDEWEB)

    Teran, M.; Paolino, A.; Savio, E. [Catedra de Radioquimica, Facultad de Quimica, Montevideo (Uruguay); Hermida, J.C. [Centro de Medicina Nuclear, Hospital de Clinicas, Facultad de Medicina, Montevideo (Uruguay); Dantas, B.M. [Laboratorio de Medidas In vivo, Instituto da Radioprotecao e Dosimetria, Rio de Janeiro (Brazil)

    2006-07-01

    The radionuclides incorporation can happen as a result of diverse activities; these include the work associated with the different stadiums of the nuclear fuel cycle, the use of radioactive sources in medicine, the scientific research, the agriculture and the industry. In Uruguay the main activities linked to the manipulation of open sources correspond those of Nuclear Medicine and from 2004, in the mark of the Project Arcal RLA 049 and being based on the Safety Guides of the IAEA it is implementing a program of internal monitoring in combined form the Nuclear Medicine Center of the Hospital of and the Radiochemistry class of the Faculty of Chemistry. In accordance with the publication of the ICRP 75 the emphasis of any monitoring program should be in the formal study of the doses in the workers to who are considered commendable of to receive in routine form an outstanding fraction of the dose limits or who work in areas where the exposures can be significant in the accident event. From April 2004, to the date has started a pilot plan by means of in that were established appropriate conditions of procedures and of safety in a reduced group of workers of the Nuclear Medicine area. In that period the first work limits, equipment adjustment, calibrations and registration systems were determined. The monitoring system implemented until the moment is carried out with a thyroid caption equipment. However these measurements are carried out in the university hospital embracing 40% of the involved workers of our country, with the purpose of reaching the covering of the biggest quantity of occupationally exposed personnel of private clinics. Also it was developed a new work proposal that allows to have an alternative measure method, in the event of not having the equipment habitually used. Among the conclusions of this work are that for the before exposed are considered the measure conditions but appropriate the following ones: Gamma Camera without collimator; Measurement

  3. A Neural Network Based Hybrid Mixture Model to Extract Information from Non-linear Mixed Pixels

    Directory of Open Access Journals (Sweden)

    Uttam Kumar

    2012-09-01

    Full Text Available Signals acquired by sensors in the real world are non-linear combinations, requiring non-linear mixture models to describe the resultant mixture spectra for the endmember’s (pure pixel’s distribution. This communication discusses inferring class fraction through a novel hybrid mixture model (HMM. HMM is a three-step process, where the endmembers are first derived from the images themselves using the N-FINDR algorithm. These endmembers are used by the linear mixture model (LMM in the second step that provides an abundance estimation in a linear fashion. Finally, the abundance values along with the training samples representing the actual ground proportions are fed into neural network based multi-layer perceptron (MLP architecture as input to train the neurons. The neural output further refines the abundance estimates to account for the non-linear nature of the mixing classes of interest. HMM is first implemented and validated on simulated hyper spectral data of 200 bands and subsequently on real time MODIS data with a spatial resolution of 250 m. The results on computer simulated data show that the method gives acceptable results for unmixing pixels with an overall RMSE of 0.0089 ± 0.0022 with LMM and 0.0030 ± 0.0001 with the HMM when compared to actual class proportions. The unmixed MODIS images showed overall RMSE with HMM as 0.0191 ± 0.022 as compared to the LMM output considered alone that had an overall RMSE of 0.2005 ± 0.41, indicating that individual class abundances obtained from HMM are very close to the real observations.

  4. Comparison Between Linear and Nonlinear Models of Mixed Pixels in Remote Sensing Satellite Images Based on Cierniewski Surface BRDF Model by Means of Monte Carlo Ray Tracing Simulation

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-04-01

    Full Text Available Comparative study on linear and nonlinear mixed pixel models of which pixels in remote sensing satellite images is composed with plural ground cover materials mixed together, is conducted for remote sensing satellite image analysis. The mixed pixel models are based on Cierniewski of ground surface reflectance model. The comparative study is conducted by using of Monte Carlo Ray Tracing: MCRT simulations. Through simulation study, the difference between linear and nonlinear mixed pixel models is clarified. Also it is found that the simulation model is validated.

  5. Comparison Effectiveness of Pixel Based Classification and Object Based Classification Using High Resolution Image In Floristic Composition Mapping (Study Case: Gunung Tidar Magelang City)

    Science.gov (United States)

    Ardha Aryaguna, Prama; Danoedoro, Projo

    2016-11-01

    Developments of analysis remote sensing have same way with development of technology especially in sensor and plane. Now, a lot of image have high spatial and radiometric resolution, that's why a lot information. Vegetation object analysis such floristic composition got a lot advantage of that development. Floristic composition can be interpreted using a lot of method such pixel based classification and object based classification. The problems for pixel based method on high spatial resolution image are salt and paper who appear in result of classification. The purpose of this research are compare effectiveness between pixel based classification and object based classification for composition vegetation mapping on high resolution image Worldview-2. The results show that pixel based classification using majority 5×5 kernel windows give the highest accuracy between another classifications. The highest accuracy is 73.32% from image Worldview-2 are being radiometric corrected level surface reflectance, but for overall accuracy in every class, object based are the best between another methods. Reviewed from effectiveness aspect, pixel based are more effective then object based for vegetation composition mapping in Tidar forest.

  6. A DC-DC converter based powering scheme for the upgrade of the CMS pixel detector

    Science.gov (United States)

    Feld, L.; Karpinski, W.; Klein, K.; Merz, J.; Sammet, J.; Wlochal, M.

    2011-11-01

    Around 2016, the pixel detector of the CMS experiment will be upgraded. The amount of current that has to be provided to the front-end electronics is expected to increase by a factor of two. Since the space available for cables is limited, this would imply unacceptable power losses in the currently installed supply cables. Therefore it is foreseen to place DC-DC converters close to the front-end electronics, allowing the provision of power at higher voltages, thereby facilitating the supply of the required currents with the present cable plant. This conference report introduces the foreseen powering scheme of the pixel upgrade. For the first time, system tests have been conducted with pixel barrel sensor modules, radiation tolerant DC-DC converters and the full power supply chain of the pixel detector. In addition, studies of the stability of different powering schemes under various conditions are summarized. In particular the impact of large and fast load variations, which are related to the bunch structure of the LHC beam, has been studied.

  7. Simulations of a silicon pixel based on MOS Deep Trapping Gate Principle

    CERN Document Server

    Fourches, Nicolas T

    2016-01-01

    The concept of the deep trapping gate device was introduced fairly recently on the basis of technological and transport simulations currently used in the field of classical electron devices. The concept of a buried gate containing localized deep level centers for holes (Deep Trapping Gate or DTG) renders possible the operation of this field effect pixel detector. One alternative to Deep Level introduction is the use of a quantum box, which is a hole quantum-well and an electron barrier. In all of these cases the buried gate modulates the drain-source current. This principle was formerly evaluated with realistic simulations parameters and this shows that a measurable signal is obtained for an energy deposition of a minimum-ionizing particle within a limited silicon thickness. In this work a quantitative study of the response of such a pixel to Minimum Ionizing Particles. The influence of some parameters such as the thickness of the pixel and its lateral dimensions, on the operation of the pixel is studied here...

  8. Research on rice acreage estimation in fragmented area based on decomposition of mixed pixels

    Science.gov (United States)

    Zhang, H.; Li, Q. Z.; Lei, F.; Du, X.; Wei, J. D.

    2015-04-01

    Rice acreage estimation is a key aspect to guarantee food security and also important to support government agricultural subsidy system. In this paper, we explored a sophisticated method to improve rice estimation accuracy at county scale and we developed our approach with China Environment Satellite HJ-1A/B data in Hunan Province, a fragmented area with complex rice cropping patterns. Our approach improved the estimation accuracy by combing supervised and unsupervised classification upon decomposition of mixed pixels model, and the rice estimation results, validated by ground survey data, showed a close relationship (RMSE~3.40) with survey figures, the estimated accuracy (EA) reached 83.74% at county level according to the sub-pixel method, and the accuracy can be increased about 12% compared to the pure-pixel method. The results suggest that decomposition of mixed pixels method has great significance to the improvement of rice acreage estimation accuracy, and can be used in mountainous and broken planting area.

  9. A hyper-chaos-based image encryption algorithm using pixel-level permutation and bit-level permutation

    Science.gov (United States)

    Li, Yueping; Wang, Chunhua; Chen, Hua

    2017-03-01

    Recently, a number of chaos-based image encryption algorithms that use low-dimensional chaotic map and permutation-diffusion architecture have been proposed. However, low-dimensional chaotic map is less safe than high-dimensional chaotic system. And permutation process is independent of plaintext and diffusion process. Therefore, they cannot resist efficiently the chosen-plaintext attack and chosen-ciphertext attack. In this paper, we propose a hyper-chaos-based image encryption algorithm. The algorithm adopts a 5-D multi-wing hyper-chaotic system, and the key stream generated by hyper-chaotic system is related to the original image. Then, pixel-level permutation and bit-level permutation are employed to strengthen security of the cryptosystem. Finally, a diffusion operation is employed to change pixels. Theoretical analysis and numerical simulations demonstrate that the proposed algorithm is secure and reliable for image encryption.

  10. P.I.X.S.C.A.N.: a micro-CT scanner for small animal based on hybrid pixel detectors; PIXSCAN: micro-tomodensitrometre a pixels hybrides pour le petit animal

    Energy Technology Data Exchange (ETDEWEB)

    Khoury, R

    2008-03-15

    Since more than a dozen years, efforts were led in the field of X-ray tomography for small animals, principally for the improvement of spatial resolution and the diminution of the absorbed dose. The C.P.P.M. developed the micro-CT P.I.X.S.C.A.N. based on the hybrid pixel detector X.P.A.D.2. In this context, my thesis work consists in studying the demonstrator P.I.X.S.C.A.N./X.P.A.D.2 and the contribution of the hybrid pixels in the imaging of small animals. A fast analytical simulation, FastSimu, was developed. An extrapolation of the performance of the demonstrator P.I.X.S.C.A.N, as well as the validation of the results obtained with the measured data, were led by means of the analytical simulator FastSimu. The demonstrator P.I.X.S.C.A.N./X.P.A.D.2 allowed to obtain reconstructed images with a rather good quality for a relatively weak absorbed dose. Its spatial resolution is degraded by the high number of defective pixels of the detector X.P.A.D.2. Beyond this study, a new version of the demonstrator P.I.X.S.C.A.N./X.P.A.D.2 is under construction. This latter, characterized by two and a half times smaller pixels and about no defective pixels will bring a considerable improvement on spatial resolution. (author)

  11. The optimisation of the laser-induced forward transfer process for fabrication of polyfluorene-based organic light-emitting diode pixels

    Energy Technology Data Exchange (ETDEWEB)

    Shaw-Stewart, James, E-mail: james.shaw-stewart@ed.ac.uk [Materials Group, General Energies Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Laboratory for Functional Polymers, Empa Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Mattle, Thomas [Materials Group, General Energies Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Lippert, Thomas, E-mail: thomas.lippert@psi.ch [Materials Group, General Energies Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Nagel, Matthias [Laboratory for Functional Polymers, Empa Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Nüesch, Frank, E-mail: frank.nueesch@empa.ch [Laboratory for Functional Polymers, Empa Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Section de science et génie des matériaux, EPFL, CH-1015 Lausanne (Switzerland); Wokaun, Alexander [Materials Group, General Energies Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland)

    2013-08-01

    Laser-induced forward transfer (LIFT) has already been used to fabricate various types of organic light-emitting diodes (OLEDs), and the process itself has been optimised and refined considerably since OLED pixels were first demonstrated. In particular, a dynamic release layer (DRL) of triazene polymer has been used, the environmental pressure has been reduced down to a medium vacuum, and the donor receiver gap has been controlled with the use of spacers. Insight into the LIFT process's effect upon OLED pixel performance is presented here, obtained through optimisation of three-colour polyfluorene-based OLEDs. A marked dependence of the pixel morphology quality on the cathode metal is observed, and the laser transfer fluence dependence is also analysed. The pixel device performances are compared to conventionally fabricated devices, and cathode effects have been looked at in detail. The silver cathode pixels show more heterogeneous pixel morphologies, and a correspondingly poorer efficiency characteristics. The aluminium cathode pixels have greater green electroluminescent emission than both the silver cathode pixels and the conventionally fabricated aluminium devices, and the green emission has a fluence dependence for silver cathode pixels.

  12. Comparison of Advanced Pixel Based (ANN and SVM) and Object-Oriented Classification Approaches Using Landsat-7 Etm+ Data

    OpenAIRE

    Prasun Kumar Gupta; Gaurav Kalidas Pakhale

    2010-01-01

    In this study, the pixel-based and object-oriented image classification approaches were used for identifying different land use types in Karnal district. Imagery from Landsat-7 ETM with 6 spectral bands was used to perform the image classification.Ground truth data were collected from the available maps, personal knowledge and communication with the local people. In order to prepare land use map different approaches: Artificial Neural Network(ANN) and Support Vector Machine (SVM) were used. F...

  13. Classification of Urban Aerial Data Based on Pixel Labelling with Deep Convolutional Neural Networks and Logistic Regression

    Science.gov (United States)

    Yao, W.; Poleswki, P.; Krzystek, P.

    2016-06-01

    The recent success of deep convolutional neural networks (CNN) on a large number of applications can be attributed to large amounts of available training data and increasing computing power. In this paper, a semantic pixel labelling scheme for urban areas using multi-resolution CNN and hand-crafted spatial-spectral features of airborne remotely sensed data is presented. Both CNN and hand-crafted features are applied to image/DSM patches to produce per-pixel class probabilities with a L1-norm regularized logistical regression classifier. The evidence theory infers a degree of belief for pixel labelling from different sources to smooth regions by handling the conflicts present in the both classifiers while reducing the uncertainty. The aerial data used in this study were provided by ISPRS as benchmark datasets for 2D semantic labelling tasks in urban areas, which consists of two data sources from LiDAR and color infrared camera. The test sites are parts of a city in Germany which is assumed to consist of typical object classes including impervious surfaces, trees, buildings, low vegetation, vehicles and clutter. The evaluation is based on the computation of pixel-based confusion matrices by random sampling. The performance of the strategy with respect to scene characteristics and method combination strategies is analyzed and discussed. The competitive classification accuracy could be not only explained by the nature of input data sources: e.g. the above-ground height of nDSM highlight the vertical dimension of houses, trees even cars and the nearinfrared spectrum indicates vegetation, but also attributed to decision-level fusion of CNN's texture-based approach with multichannel spatial-spectral hand-crafted features based on the evidence combination theory.

  14. The use of airborne laser scanning to develop a pixel-based stratification for a verified carbon offset project

    Science.gov (United States)

    2011-01-01

    Background The voluntary carbon market is a new and growing market that is increasingly important to consider in managing forestland. Monitoring, reporting, and verifying carbon stocks and fluxes at a project level is the single largest direct cost of a forest carbon offset project. There are now many methods for estimating forest stocks with high accuracy that use both Airborne Laser Scanning (ALS) and high-resolution optical remote sensing data. However, many of these methods are not appropriate for use under existing carbon offset standards and most have not been field tested. Results This paper presents a pixel-based forest stratification method that uses both ALS and optical remote sensing data to optimally partition the variability across an ~10,000 ha forest ownership in Mendocino County, CA, USA. This new stratification approach improved the accuracy of the forest inventory, reduced the cost of field-based inventory, and provides a powerful tool for future management planning. This approach also details a method of determining the optimum pixel size to best partition a forest. Conclusions The use of ALS and optical remote sensing data can help reduce the cost of field inventory and can help to locate areas that need the most intensive inventory effort. This pixel-based stratification method may provide a cost-effective approach to reducing inventory costs over larger areas when the remote sensing data acquisition costs can be kept low on a per acre basis. PMID:22004847

  15. A memristor-based pixel implementing light-to-resistance conversion

    Science.gov (United States)

    Olumodeji, Olufemi A.; Bramanti, Alessandro P.; Gottardi, Massimo; Iannotta, Salvatore

    2016-02-01

    This letter reports a pixel architecture that implements a light-to-resistance encoder exploiting the properties of a memristor. A light-to-frequency (L2F) converter is adopted to drive a memristor with pulses, thus changing its resistance according with the light intensity. In a conventional L2F implementation, a binary counter is needed to store the number of pulses generated within the exposure time (Ti). In the proposed circuit, the binary counter has been replaced with an analog counterpart, made of a single memristor. This turns into a smaller pixel pitch, compared with an all-CMOS solution and analog nonvolatile characteristics. The proposed circuit has been simulated in a 3.3 V, 0.35 μm CMOS process, while the memristor behavior relies on the HP model.

  16. Fully Pipelined Parallel Architecture for Candidate Block and Pixel-Subsampling-Based Motion Estimation

    Directory of Open Access Journals (Sweden)

    Reeba Korah

    2008-01-01

    Full Text Available This paper presents a low power and high speed architecture for motion estimation with Candidate Block and Pixel Subsampling (CBPS Algorithm. Coarse-to-fine search approach is employed to find the motion vector so that the local minima problem is totally eliminated. Pixel subsampling is performed in the selected candidate blocks which significantly reduces computational cost with low quality degradation. The architecture developed is a fully pipelined parallel design with 9 processing elements. Two different methods are deployed to reduce the power consumption, parallel and pipelined implementation and parallel accessing to memory. For processing 30 CIF frames per second our architecture requires a clock frequency of 4.5 MHz.

  17. A VME MXI-II Based Setup for Testing ALICE Pixel Readout Prototypes

    CERN Document Server

    Chochula, P; CERN. Geneva

    2000-01-01

    Abstract One of the possible readout scenarios for ALICE ITS pixel layers counts on in- situ zero suppression, performed by Pilot control chip. Preprocessed event will be then serialized and sent out via about 50 m long copper cable for further processing. The VME prototypes of Pilot chip and link (called "SHORTLINK") were developed in the frames of Alice collaboration. Here we describe the VME test system, developed to test the modules.

  18. Performance improvement in amorphous silicon based uncooled microbolometers through pixel design and materials development

    Science.gov (United States)

    Ajmera, Sameer; Brady, John; Hanson, Charles; Schimert, Tom; Syllaios, A. J.; Taylor, Michael

    2011-06-01

    Uncooled amorphous silicon microbolometers have been established as a field-worthy technology for a broad range of applications where performance and form factor are paramount, such as soldier-borne systems. Recent developments in both bolometer materials and pixel design at L-3 in the 17μm pixel node have further advanced the state-of-the-art. Increasing the a-Si material temperature coefficient of resistance (TCR) has the impact of improving NETD sensitivity without increasing thermal time constant (TTC), leading to an improvement in the NETD×TTC product. By tuning the amorphous silicon thin-film microstructure using hydrogen dilution during deposition, films with high TCR have been developed. The electrical properties of these films have been shown to be stable even after thermal cycling to temperatures greater than 300oC enabling wafer-level vacuum packaging currently performed at L-3 to reduce the size and weight of the vacuum packaged unit. Through appropriate selection of conditions during deposition, amorphous silicon of ~3.4% TCR has been integrated into the L-3 microbolometer manufacturing flow. By combining pixel design enhancements with improvements to amorphous silicon thin-film technology, L-3's amorphous silicon microbolometer technology will continue to provide the performance required to meet the needs to tomorrow's war-fighter.

  19. Efficient Processing of a Rainfall Simulation Watershed on an FPGA-Based Architecture with Fast Access to Neighbourhood Pixels

    Directory of Open Access Journals (Sweden)

    Yeong LeeSeng

    2009-01-01

    Full Text Available This paper describes a hardware architecture to implement the watershed algorithm using rainfall simulation. The speed of the architecture is increased by utilizing a multiple memory bank approach to allow parallel access to the neighbourhood pixel values. In a single read cycle, the architecture is able to obtain all five values of the centre and four neighbours for a 4-connectivity watershed transform. The storage requirement of the multiple bank implementation is the same as a single bank implementation by using a graph-based memory bank addressing scheme. The proposed rainfall watershed architecture consists of two parts. The first part performs the arrowing operation and the second part assigns each pixel to its associated catchment basin. The paper describes the architecture datapath and control logic in detail and concludes with an implementation on a Xilinx Spartan-3 FPGA.

  20. Efficient Processing of a Rainfall Simulation Watershed on an FPGA-Based Architecture with Fast Access to Neighbourhood Pixels

    Directory of Open Access Journals (Sweden)

    Kah Phooi Seng

    2009-01-01

    Full Text Available This paper describes a hardware architecture to implement the watershed algorithm using rainfall simulation. The speed of the architecture is increased by utilizing a multiple memory bank approach to allow parallel access to the neighbourhood pixel values. In a single read cycle, the architecture is able to obtain all five values of the centre and four neighbours for a 4-connectivity watershed transform. The storage requirement of the multiple bank implementation is the same as a single bank implementation by using a graph-based memory bank addressing scheme. The proposed rainfall watershed architecture consists of two parts. The first part performs the arrowing operation and the second part assigns each pixel to its associated catchment basin. The paper describes the architecture datapath and control logic in detail and concludes with an implementation on a Xilinx Spartan-3 FPGA.

  1. Towards a deep characterization of a 64-fold-pixelated position sensitive detector for a new {gamma}-scanning system of HPGe segmented detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Prieto, A.; Quintana, B. [Laboratorio de Radiaciones Ionizantes, Univ. of Salamanca, 37007 (Spain)

    2011-07-01

    Characterization of the electrical response of the HPGe segmented detectors is one of the current goals for the Nuclear Physics community in order to perform {gamma}-ray tracking or even imaging with these detectors. For this purpose, scanning devices have to be developed to achieve the signal-position association with the highest precision. In this laboratory, a new scanning system, SALSA (Salamanca Lyso-based Scanning Array), consisting on a high spatial resolution {gamma} camera, is a under development. In this work the whole scanning system is presented and first results for the characterization of the {gamma} camera are shown. (authors)

  2. Breast Imaging Utilizing Dedicated Gamma Camera and (99m)Tc-MIBI: Experience at the Tel Aviv Medical Center and Review of the Literature Breast Imaging.

    Science.gov (United States)

    Even-Sapir, Einat; Golan, Orit; Menes, Tehillah; Weinstein, Yuliana; Lerman, Hedva

    2016-07-01

    The scope of the current article is the clinical role of gamma cameras dedicated for breast imaging and (99m)Tc-MIBI tumor-seeking tracer, as both a screening modality among a healthy population and as a diagnostic modality in patients with breast cancer. Such cameras are now commercially available. The technology utilizing a camera composed of a NaI (Tl) detector is termed breast-specific gamma imaging. The technology of dual-headed camera composed of semiconductor cadmium zinc telluride detectors that directly converts gamma-ray energy into electronic signals is termed molecular breast imaging. Molecular breast imaging system has been installed at the Department of Nuclear medicine at the Tel Aviv Sourasky Medical Center, Tel Aviv in 2009. The article reviews the literature well as our own experience. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Uteroplacental blood flow in pre-eclampsia measurements with /sup 113 m/In and a computer-linked gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Lunell, N.O.; Nylund, L.E.; Lewander, R.; Sarby, B.

    1982-01-01

    Uteroplacental blood flow was measured with a computer-linked gamma camera after intravenous injection of 1 mCi /sup 113/In. Results of the measurements from 32 pre-eclamptic pregnancies and 37 normal controls are compared. The uteroplacental blood flow was measured as an index calculated from the rise time and maximum activity of the isotope accumulation curve. The uteroplacental blood flow was reduced with 50% in pre-eclampsia. In severe pre-eclampsia it was more compromised than in mild pre-eclampsia. A diminished uteroplacental blood flow was found in pre-eclampsia even in the absence of intrauterine growth retardation. The maternal placental circulation in the supine position was reduced with one third compared to that in the left lateral recumbent position.

  4. Evaluation of Origin Ensemble algorithm for image reconstruction for pixelated solid-state detectors with large number of channels

    Science.gov (United States)

    Kolstein, M.; De Lorenzo, G.; Mikhaylova, E.; Chmeissani, M.; Ariño, G.; Calderón, Y.; Ozsahin, I.; Uzun, D.

    2013-04-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated solid-state technology for nuclear medicine applications. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). For PET scanners, conventional algorithms like Filtered Back-Projection (FBP) and Ordered Subset Expectation Maximization (OSEM) are straightforward to use and give good results. However, FBP presents difficulties for detectors with limited angular coverage like PEM and Compton gamma cameras, whereas OSEM has an impractically large time and memory consumption for a Compton gamma camera with a large number of channels. In this article, the Origin Ensemble (OE) algorithm is evaluated as an alternative algorithm for image reconstruction. Monte Carlo simulations of the PET design are used to compare the performance of OE, FBP and OSEM in terms of the bias, variance and average mean squared error (MSE) image quality metrics. For the PEM and Compton camera designs, results obtained with OE are presented.

  5. Theoretical investigation of the noise performance of active pixel imaging arrays based on polycrystalline silicon thin film transistors.

    Science.gov (United States)

    Koniczek, Martin; Antonuk, Larry E; El-Mohri, Youcef; Liang, Albert K; Zhao, Qihua

    2017-07-01

    Active matrix flat-panel imagers, which typically incorporate a pixelated array with one a-Si:H thin-film transistor (TFT) per pixel, have become ubiquitous by virtue of many advantages, including large monolithic construction, radiation tolerance, and high DQE. However, at low exposures such as those encountered in fluoroscopy, digital breast tomosynthesis and breast computed tomography, DQE is degraded due to the modest average signal generated per interacting x-ray relative to electronic additive noise levels of ~1000 e, or greater. A promising strategy for overcoming this limitation is to introduce an amplifier into each pixel, referred to as the active pixel (AP) concept. Such circuits provide in-pixel amplification prior to readout as well as facilitate correlated multiple sampling, enhancing signal-to-noise and restoring DQE at low exposures. In this study, a methodology for theoretically investigating the signal and noise performance of imaging array designs is introduced and applied to the case of AP circuits based on low-temperature polycrystalline silicon (poly-Si), a semiconductor suited to manufacture of large area, radiation tolerant arrays. Computer simulations employing an analog circuit simulator and performed in the temporal domain were used to investigate signal characteristics and major sources of electronic additive noise for various pixel amplifier designs. The noise sources include photodiode shot noise and resistor thermal noise, as well as TFT thermal and flicker noise. TFT signal behavior and flicker noise were parameterized from fits to measurements performed on individual poly-Si test TFTs. The performance of three single-stage and three two-stage pixel amplifier designs were investigated under conditions relevant to fluoroscopy. The study assumes a 20 × 20 cm(2) , 150 μm pitch array operated at 30 fps and coupled to a CsI:Tl x-ray converter. Noise simulations were performed as a function of operating conditions, including

  6. Real-time breath-hold triggering of myocardial perfusion imaging with a novel cadmium-zinc-telluride detector gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Buechel, Ronny R.; Pazhenkottil, Aju P.; Herzog, Bernhard A.; Husmann, Lars; Nkoulou, Rene N.; Burger, Irene A.; Valenta, Ines; Wyss, Christophe A.; Ghadri, Jelena R. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University of Zurich, Zurich Center for Integrative Human Physiology (ZIHP), Zurich (Switzerland)

    2010-10-15

    The aim of this study was to assess the ability of real-time breath-hold-triggered myocardial perfusion imaging (MPI) using a novel cadmium-zinc-telluride (CZT) gamma camera to discriminate artefacts from true perfusion defects. A group of 40 patients underwent a 1-day {sup 99m}Tc-tetrofosmin pharmacological stress/rest imaging protocol on a conventional dual detector SPECT gamma camera with and without attenuation correction (AC), immediately followed by scanning on an ultrafast CZT camera with and without real-time breath-hold triggering (instead of AC) by intermittent scanning confined to breath-hold at deep inspiration (using list mode acquisition). We studied the use of breath-hold triggering on the CZT camera and its ability to discriminate artefacts from true perfusion defects using AC SPECT MPI as the reference standard. Myocardial tracer uptake (percent of maximum) from CZT was compared to AC SPECT MPI by intraclass correlation and by calculating Bland-Altman limits of agreement. AC of SPECT MPI identified 19 apparent perfusion defects as artefacts. Of these, 13 were correctly identified and 4 were partially unmasked (decrease in extent and/or severity) by breath-hold triggering of the CZT scan. All perfusion defects verified by SPECT MPI with AC were appropriately documented by CZT with and without breath-hold triggering. This was supported by the quantitative analysis, as the correlation (r) of myocardial tracer uptake between CZT and AC SPECT improved significantly from 0.81 to 0.90 (p<0.001) when applying breath-hold triggering. Similarly, Bland-Altman limits of agreement were narrower for CZT scans with breath-hold triggering. This novel CZT camera allows real-time breath-hold triggering as a potential alternative to AC to assist in the discrimination of artefacts from true perfusion defects. (orig.)

  7. The intraoperative use of the mini-gamma camera (MGC) in the surgical treatment of primary hyperparathyroidism: Technical reports and immediate results from the initial experience.

    Science.gov (United States)

    Scerrino, Gregorio; Castorina, Serena; Melfa, Giuseppina Irene; Lo Piccolo, Clotilde; Raspanti, Cristina; Richiusa, Pierina; Costa, Renato Patrizio; Gulotta, Gaspare

    2015-01-01

    Il trattamento dell’iperparatiroidismo primario è quasi esclusivamente chirurgico e consiste nell’esplorazione sistematica delle quattro ghiandole con asportazione di quella( e) patologica(e). Le più moderne tecniche di diagnosi (ecotomografia, scintigrafia 99 mTc sestamibi), migliorando le possibilità di individuare la ghiandola responsabile della malattia, consentono l’esecuzione di tecniche miniinvasive quando vi è concordanza tra i risultati delle due tecniche, ma la sensibilità di tali indagini è inficiata dalle ectopie ghiandolari, da paratiroidi intratiroidee, da malattia multighiandolare o dalla contemporanea presenza di malattie tiroidee. Il presente studio illustra una nuova tecnica di imaging scintigrafico intraoperatorio ed indaga sulla sua possibilità di migliorare la localizzazione intraoperatoria della paratiroide patologica. A tal fine, 5 pazienti sono state sottoposte a tale metodica, tutte trattate con paratiroidectomia previa esplorazione completa delle quattro ghiandole con tecnica tradizionale, con monitoraggio intraoperatorio del paratormone. Alla tecnica convenzionale è stato aggiunto l’impiego della gamma camera intraoperatoria. Abbiamo valutato la concordanza dei risultati di tale esame con i dati dell’esplorazione chirurgica e con il dosaggio intraoperatorio del paratormone. In tutte e 5 le pazienti si è osservata una perfetta concordanza tra la localizzazione della ghiandola patologica con la scintigrafia intraoperatoria e l’esplorazione chirurgica, ed il dosaggio intraoperatorio del paratormone ha confermato i dati. Anche il follow-up ad un mese ha confermato l’eradicazione della malattia. La gamma camera intraoperatoria sembra quindi poter migliorare le possibilità di localizzazione della ghiandola responsabile dell’iperparati-roidismo primario, favorendo l’impiego di tecniche mini-invasive e migliorando i risultati dinanzi a casi “difficili”.

  8. Dynamic phase measurements based on a polarization Michelson interferometer employing a pixelated polarization camera

    Science.gov (United States)

    Serrano-Garcia, David I.; Otani, Yukitoshi

    2017-02-01

    We implemented an interferometric configuration capable of following a phase variation in time. By using a pixelated polarization camera, the system is able to retrieve the phase information instantaneously avoiding the usage of moving components and the necessity of an extra replication method attached at the output of the interferometer. Taking into account the temporal stability obtained from the system, a spatial-temporal phase demodulation algorithm can be implemented on frequency domain for the dynamic phase measurement. Spatial resolution is analyzed experimentally using a USAF pattern, and dynamic phase measurements were done on air and water medium variations due to a jet flame and a living fish as a biological sample, respectively.

  9. Optimizing land cover change detection using combined pixel-based and object-based image classification in a mountainous area in Mexico

    NARCIS (Netherlands)

    Aguirre Gutiérrez, J.; Seijmonsbergen, A.C.; Duivenvoorden, J.; Epiphanio, J.C.N.; Galvão, L.S.; dos Campos, S.J.

    2011-01-01

    Inventories of past and present land cover changes form the basis for future conservation strategies and landscape management. In this study Landsat images of a mountainous area in Mexico are used in an object-based and pixel-based image classification. The land cover categories with the highest

  10. Porous media microstructure reconstruction using pixel-based and object-based simulated annealing: comparison with other reconstruction methods

    Energy Technology Data Exchange (ETDEWEB)

    Diogenes, Alysson N.; Santos, Luis O.E. dos; Fernandes, Celso P. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil); Appoloni, Carlos R. [Universidade Estadual de Londrina (UEL), PR (Brazil)

    2008-07-01

    The reservoir rocks physical properties are usually obtained in laboratory, through standard experiments. These experiments are often very expensive and time-consuming. Hence, the digital image analysis techniques are a very fast and low cost methodology for physical properties prediction, knowing only geometrical parameters measured from the rock microstructure thin sections. This research analyzes two methods for porous media reconstruction using the relaxation method simulated annealing. Using geometrical parameters measured from rock thin sections, it is possible to construct a three-dimensional (3D) model of the microstructure. We assume statistical homogeneity and isotropy and the 3D model maintains porosity spatial correlation, chord size distribution and d 3-4 distance transform distribution for a pixel-based reconstruction and spatial correlation for an object-based reconstruction. The 2D and 3D preliminary results are compared with microstructures reconstructed by truncated Gaussian methods. As this research is in its beginning, only the 2D results will be presented. (author)

  11. Hyperspectral time-resolved wide-field fluorescence molecular tomography based on structured light and single-pixel detection.

    Science.gov (United States)

    Pian, Qi; Yao, Ruoyang; Zhao, Lingling; Intes, Xavier

    2015-02-01

    We present a time-resolved fluorescence diffuse optical tomography platform that is based on wide-field structured illumination, single-pixel detection, and hyperspectral acquisition. Two spatial light modulators (digital micro-mirror devices) are employed to generate independently wide-field illumination and detection patterns, coupled with a 16-channel spectrophotometer detection module to capture hyperspectral time-resolved tomographic data sets. The main system characteristics are reported, and we demonstrate the feasibility of acquiring dense 4D tomographic data sets (space, time, spectra) for time domain 3D quantitative multiplexed fluorophore concentration mapping in turbid media.

  12. A highly pixelated CdZnTe detector based on \\textit{Topmetal-${II}^-$} sensor

    CERN Document Server

    Zou, Shuguang; Sun, Xiangming; Huang, Guangming; Pei, Hua; Wang, Zhen; Liu, Jun; Yang, Ping; Wang, Dong

    2016-01-01

    \\textit{Topmetal-${II}^-$} is a low noise CMOS pixel direct charge sensor with a pitch of 83$\\mu m$. CdZnTe is an excellent semiconductor material for radiation detection. The combination of CdZnTe and the sensor makes it possible to build a detector with high spatial resolution. In our experiments, an epoxy adhesive is used as the conductive medium to connect the sensor and CdZnTe. The diffusion coefficient and charge efficiency of electrons are measured at a low bias voltage of -2 Volts, and the image of a single alpha is clear with a reasonable spatial resolution. The detector of such structure has the potential to be applied in X-ray imaging systems with a further improvements of the sensor.

  13. Characterization and performance studies of high-voltage CMOS based pixel sensors

    CERN Document Server

    Smaranda, Dumitru Dan

    2015-01-01

    The high luminosity upgrade of the LHC will push the limits for detectors, specially the silicon trackers which are closest to the interaction point. The ATLAS CMOS Sensor R&D efort is investigating a new technology using high-voltage CMOS processes for producing pixel and strip sensors. In contrast to the currently used technology these devices implement active electronics on the sensor itself, offering a multitude of tuning parameters for achieving the best performance. My summer project revolved around characterising existing samples along with assembling and debugging hardware required for their improvement and functionality. Other tasks involved writing communication protocols using pyBAR to remotely control injection circuitry on a GPAC card, and helping various members of the group with data collection and analysis. Through the summer student programme I have had the opportunity to be part of a vibrant scientic community at the forefront of research, to create bonds with fellow students from univ...

  14. Silicon MOS Pixel Based on the Deep Trapping Gate Principle: Design and Material Science Challenges

    CERN Document Server

    Fourches, Nicolas T

    2014-01-01

    The concept of the deep trapping gate device was introduced fairly recently on the basis of technological and transport simulations currently used in the field of classical electron devices. The concept of a buried gate containing localized deep level centers (Deep Trapping Gate or DTG) renders possible the operation of this field effect pixel detector. The deep centers can be deep defects or localized states in a quantum dot. This gate modulates the drain-source current. This principle was formerly evaluated with realistic simulations parameters and this shows that a measurable signal is obtained for an energy deposition of a minimum ionizing particle within a limited silicon thickness. We will study here the potential techniques usable for the fabrication of the device with their drawbacks, advantages and limits. The first technique introduced is impurity implantation, followed by annealing. The problems related to the control of the defects in the DTG will be examined in the light of recent work on ion imp...

  15. Performance and track-based alignment of the Phase-1 upgraded CMS pixel detector

    CERN Document Server

    Botta, Valeria

    2017-01-01

    The Compact Muon Solenoid (CMS) detector is a multi-purpose detector constructed in order to study high-energy particle collisions at the Large Hadron Collider (LHC) at CERN. The all-silicon design of the tracking system of the CMS experiment provided excellent resolution for charged tracks and an efficient tagging of jets during Run 1 and Run 2 of the LHC. After the pixel detector of the CMS experiment was upgraded and installed during the shutdown in the beginning of 2017, the positions and orientations of the tracker modules needed to be determined with a precision of several micrometers. The alignment also needs to be quickly recalculated each time the state of the CMS magnet is changed between 0 T and 3.8 T. The latest results of the CMS tracker performance in the 2017 run are presented, with a special focus on alignment and resolution performance using several million reconstructed tracks from cosmic rays and collision data.

  16. Signal and noise transfer properties of CMOS based active pixel flat panel imager coupled to structured CsI:Tl.

    Science.gov (United States)

    Arvanitis, C D; Bohndiek, S E; Blakesley, J; Olivo, A; Speller, R D

    2009-01-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors can be optically coupled to CsI:Tl phosphors forming a indirect active pixel flat panel imager (APFPI) for high performance medical imaging. The aim of this work is to determine the x-ray imaging capabilities of CMOS-based APFPI and study the signal and noise transfer properties of CsI:Tl phosphors. Three different CsI:Tl phosphors from two different vendors have been used to produce three system configurations. The performance of each system configuration has been studied in terms of the modulation transfer function (MTF), noise power spectra, and detective quantum efficiency (DQE) in the mammographic energy range. A simple method to determine quantum limited systems in this energy range is also presented. In addition, with aid of monochromatic synchrotron radiation, the effect of iodine characteristic x-rays of the CsI:Tl on the MTF has been determined. A Monte Carlo simulation of the signal transfer properties of the imager is also presented in order to study the stages that degrade the spatial resolution of our current system. The effect of using substrate patterning during the growth of CsI:Tl columnar structure was also studied, along with the effect of CsI:Tl fixed pattern noise due to local variations in the scintillation light. CsI:Tl fixed pattern noise appears to limit the performance of our current system configurations. All the system configurations are quantum limited at 0.23 microC/kg with two of them having DQE (0) equal to 0.57. Active pixel flat panel imagers are shown to be digital x-ray imagers with almost constant DQE throughout a significant part of their dynamic range and in particular at very low exposures.

  17. Land Cover and Land Use Classification with TWOPAC: towards Automated Processing for Pixel- and Object-Based Image Classification

    Directory of Open Access Journals (Sweden)

    Stefan Dech

    2012-09-01

    Full Text Available We present a novel and innovative automated processing environment for the derivation of land cover (LC and land use (LU information. This processing framework named TWOPAC (TWinned Object and Pixel based Automated classification Chain enables the standardized, independent, user-friendly, and comparable derivation of LC and LU information, with minimized manual classification labor. TWOPAC allows classification of multi-spectral and multi-temporal remote sensing imagery from different sensor types. TWOPAC enables not only pixel-based classification, but also allows classification based on object-based characteristics. Classification is based on a Decision Tree approach (DT for which the well-known C5.0 code has been implemented, which builds decision trees based on the concept of information entropy. TWOPAC enables automatic generation of the decision tree classifier based on a C5.0-retrieved ascii-file, as well as fully automatic validation of the classification output via sample based accuracy assessment.Envisaging the automated generation of standardized land cover products, as well as area-wide classification of large amounts of data in preferably a short processing time, standardized interfaces for process control, Web Processing Services (WPS, as introduced by the Open Geospatial Consortium (OGC, are utilized. TWOPAC’s functionality to process geospatial raster or vector data via web resources (server, network enables TWOPAC’s usability independent of any commercial client or desktop software and allows for large scale data processing on servers. Furthermore, the components of TWOPAC were built-up using open source code components and are implemented as a plug-in for Quantum GIS software for easy handling of the classification process from the user’s perspective.

  18. Occult Breast Cancer: Scintimammography with High-Resolution Breast-specific Gamma Camera in Women at High Risk for Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Rachel F. Brem; Jocelyn A. Rapelyea; , Gilat Zisman; Kevin Mohtashemi; Joyce Raub; Christine B. Teal; Stan Majewski; Benjamin L. Welch

    2005-08-01

    To prospectively evaluate a high-resolution breast-specific gamma camera for depicting occult breast cancer in women at high risk for breast cancer but with normal mammographic and physical examination findings. MATERIALS AND METHODS: Institutional Review Board approval and informed consent were obtained. The study was HIPAA compliant. Ninety-four high-risk women (age range, 36-78 years; mean, 55 years) with normal mammographic (Breast Imaging Reporting and Data System [BI-RADS] 1 or 2) and physical examination findings were evaluated with scintimammography. After injection with 25-30 mCi (925-1110 MBq) of technetium 99m sestamibi, patients were imaged with a high-resolution small-field-of-view breast-specific gamma camera in craniocaudal and mediolateral oblique projections. Scintimammograms were prospectively classified according to focal radiotracer uptake as normal (score of 1), with no focal or diffuse uptake; benign (score of 2), with minimal patchy uptake; probably benign (score of 3), with scattered patchy uptake; probably abnormal (score of 4), with mild focal radiotracer uptake; and abnormal (score of 5), with marked focal radiotracer uptake. Mammographic breast density was categorized according to BI-RADS criteria. Patients with normal scintimammograms (scores of 1, 2, or 3) were followed up for 1 year with an annual mammogram, physical examination, and repeat scintimammography. Patients with abnormal scintimammograms (scores of 4 or 5) underwent ultrasonography (US), and those with focal hypoechoic lesions underwent biopsy. If no lesion was found during US, patients were followed up with scintimammography. Specific pathologic findings were compared with scintimammographic findings. RESULTS: Of 94 women, 78 (83%) had normal scintimammograms (score of 1, 2, or 3) at initial examination and 16 (17%) had abnormal scintimammograms (score of 4 or 5). Fourteen (88%) of the 16 patients had either benign findings at biopsy or no focal abnormality at US; in two

  19. Supervised Classification of Benthic Reflectance in Shallow Subtropical Waters Using a Generalized Pixel-Based Classifier across a Time Series

    Directory of Open Access Journals (Sweden)

    Tara Blakey

    2015-04-01

    Full Text Available We tested a supervised classification approach with Landsat 5 Thematic Mapper (TM data for time-series mapping of seagrass in a subtropical lagoon. Seagrass meadows are an integral link between marine and inland ecosystems and are at risk from upstream processes such as runoff and erosion. Despite the prevalence of image-specific approaches, the classification accuracies we achieved show that pixel-based spectral classes may be generalized and applied to a time series of images that were not included in the classifier training. We employed in-situ data on seagrass abundance from 2007 to 2011 to train and validate a classification model. We created depth-invariant bands from TM bands 1, 2, and 3 to correct for variations in water column depth prior to building the classification model. In-situ data showed mean total seagrass cover remained relatively stable over the study area and period, with seagrass cover generally denser in the west than the east. Our approach achieved mapping accuracies (67% and 76% for two validation years comparable with those attained using spectral libraries, but was simpler to implement. We produced a series of annual maps illustrating inter-annual variability in seagrass occurrence. Accuracies may be improved in future work by better addressing the spatial mismatch between pixel size of remotely sensed data and footprint of field data and by employing atmospheric correction techniques that normalize reflectances across images.

  20. Pixel-Based Land Cover Classification by Fusing Hyperspectral and LIDAR Data

    Science.gov (United States)

    Jahan, F.; Awrangjeb, M.

    2017-09-01

    Land cover classification has many applications like forest management, urban planning, land use change identification and environment change analysis. The passive sensing of hyperspectral systems can be effective in describing the phenomenology of the observed area over hundreds of (narrow) spectral bands. On the other hand, the active sensing of LiDAR (Light Detection and Ranging) systems can be exploited for characterising topographical information of the area. As a result, the joint use of hyperspectral and LiDAR data provides a source of complementary information, which can greatly assist in the classification of complex classes. In this study, we fuse hyperspectral and LiDAR data for land cover classification. We do a pixel-wise classification on a disjoint set of training and testing samples for five different classes. We propose a new feature combination by fusing features from both hyperspectral and LiDAR, which achieves competent classification accuracy with low feature dimension, while the existing method requires high dimensional feature vector to achieve similar classification result. Also, for the reduction of the dimension of the feature vector, Principal Component Analysis (PCA) is used as it captures the variance of the samples with a limited number of Principal Components (PCs). We tested our classification method using PCA applied on hyperspectral bands only and combined hyperspectral and LiDAR features. Classification with support vector machine (SVM) and decision tree shows that our feature combination achieves better classification accuracy compared to the existing feature combination, while keeping the similar number of PCs. The experimental results also show that decision tree performs better than SVM and requires less execution time.

  1. Comparison of uteroplacental blood flow in normal and pre-eclamptic patients measurement with technetium-99m and a computer-linked gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S.H.; Moon, H.; Kim, D.S.; Cho, S.S.

    1985-05-01

    Uteroplacental blood flow studies in preeclampsia are of special interest since the vascular changes reported in this disease might constitute a structural basis for a reduction of blood flow. Evidence has also been given for a decreased uteroplacental blood flow in preeclampsia. Among the various methods to estimate the maternal placental blood flow, the one most frequently reported in the literature during the last years has been the time activity analysis of short lived radiotracer such as technetium-99m or indium-113m injected intravenously. Only few studies with the above mentioned technique comparing normal and preeclampsia cases have been undertaken. In clinical practice we frequently experience difficuly in finding the optimal time to get the delivery in preeclampsia patients. The aim of this study was first to measure uteroplacental blood flow in preeclamptic pregnancies using a computer-linked gamma camera method for the time-activity analysis of technetium-99m and second to discuss the possibility of clinical application of these measurements for determination of fetal well-being and the timing of the delivery in these patients. Uteroplacental blood flow was measured from 13 preeclamptic patients and 19 pregnancies without any complication after 35 completed weeks of gestation from Jan. 1983 to Sep. 1983 at Obstetrics department of Hanyang University Hospital. (Author).

  2. A variation pixels identification method based on kernel spatial attraction model and local entropy for robust endmember extraction

    Institute of Scientific and Technical Information of China (English)

    赵春晖; 田明华; 齐滨; 王玉磊

    2016-01-01

    A variation pixels identification method was proposed aiming at depressing the effect of variation pixels, which dilates the theoretical hyperspectral data simplex and misguides volume evaluation of the simplex. With integration of both spatial and spectral information, this method quantitatively defines a variation index for every pixel. The variation index is proportional to pixels local entropy but inversely proportional to pixels kernel spatial attraction. The number of pixels removed was modulated by an artificial threshold factorα. Two real hyperspectral data sets were employed to examine the endmember extraction results. The reconstruction errors of preprocessing data as opposed to the result of original data were compared. The experimental results show that the number of distinct endmembers extracted has increased and the reconstruction error is greatly reduced. 100% is an optional value for the threshold factorα when dealing with no prior knowledge hyperspectral data.

  3. Development of a pixel sensor with fine space-time resolution based on SOI technology for the ILC vertex detector

    Science.gov (United States)

    Ono, Shun; Togawa, Manabu; Tsuji, Ryoji; Mori, Teppei; Yamada, Miho; Arai, Yasuo; Tsuboyama, Toru; Hanagaki, Kazunori

    2017-02-01

    We have been developing a new monolithic pixel sensor with silicon-on-insulator (SOI) technology for the International Linear Collider (ILC) vertex detector system. The SOI monolithic pixel detector is realized using standard CMOS circuits fabricated on a fully depleted sensor layer. The new SOI sensor SOFIST can store both the position and timing information of charged particles in each 20×20 μm2 pixel. The position resolution is further improved by the position weighted with the charges spread to multiple pixels. The pixel also records the hit timing with an embedded time-stamp circuit. The sensor chip has column-parallel analog-to-digital conversion (ADC) circuits and zero-suppression logic for high-speed data readout. We are designing and evaluating some prototype sensor chips for optimizing and minimizing the pixel circuit.

  4. CMOS digital pixel sensors: technology and applications

    Science.gov (United States)

    Skorka, Orit; Joseph, Dileepan

    2014-04-01

    CMOS active pixel sensor technology, which is widely used these days for digital imaging, is based on analog pixels. Transition to digital pixel sensors can boost signal-to-noise ratios and enhance image quality, but can increase pixel area to dimensions that are impractical for the high-volume market of consumer electronic devices. There are two main approaches to digital pixel design. The first uses digitization methods that largely rely on photodetector properties and so are unique to imaging. The second is based on adaptation of a classical analog-to-digital converter (ADC) for in-pixel data conversion. Imaging systems for medical, industrial, and security applications are emerging lower-volume markets that can benefit from these in-pixel ADCs. With these applications, larger pixels are typically acceptable, and imaging may be done in invisible spectral bands.

  5. Development of a Time-resolved Neutron Imaging Detector Based on the {\\mu}PIC Micro-Pixel Chamber

    CERN Document Server

    Parker, Joseph D; Hattori, Kaori; Iwaki, Satoru; Kabuki, Shigeto; Kishimoto, Yuji; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nishimura, Hironobu; Oku, Takayuki; Sawano, Tatsuya; Shinohara, Takenao; Suzuki, Jun-ichi; Takada, Atsushi; Tanimori, Toru; Ueno, Kazuki; Ikeno, Masahiro; Tanaka, Manobu; Uchida, Tomohisa

    2013-01-01

    We have developed a prototype time-resolved neutron imaging detector employing a micro-pattern gaseous detector known as the micro-pixel chamber ({\\mu}PIC) coupled with a field-programmable-gate-array-based data acquisition system. Our detector system combines 100{\\mu}m-level spatial and sub-{\\mu}s time resolutions with a low gamma sensitivity of less than 10^-12 and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. In the present paper, we introduce the detector system and present several test measurements performed at NOBORU (BL10), J-PARC to demonstrate the capabilities of our prototype. We also discuss future improvements to the spatial resolution and rate performance.

  6. Alpine Pixel Detector Layout

    CERN Document Server

    Delebecque, P; The ATLAS collaboration; Geffroy, N; Massol, N; Rambure, T; Todorov, T

    2013-01-01

    A description of an optimized layout of pixel sensors based on a stave that combines both barrel and endcap module orientations. The mechanical stiffness of the structure is provided by carbon fiber shells spaced by carbon foam. The cooling of the modules is provided by two-phase $CO_{2}$ flowing in a thin titanium pipe glued inside the carbon fiber foam. The electrical services of all modules are provided by a single stave flex. This layout eliminates the need for separate barrel and endcap detector structures, and therefore the barrel services material in front of the endcap. The transition from barrel to endcap module orientation is optimized separately for each layer in order to minimize the active pixel area and the traversed material. The sparse module spacing in the endcap part of the stave allows for multiple fixation points, and for a stiff overall structure composed only of staves interconnected by stiff disks.

  7. Imaging of moving fiducial markers during radiotherapy using a fast, efficient active pixel sensor based EPID

    Energy Technology Data Exchange (ETDEWEB)

    Osmond, John P. F.; Zin, Hafiz M.; Harris, Emma J.; Lupica, Giovanni; Allinson, Nigel M.; Evans, Philip M. [Joint Department of Physics, Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey, SM2 5PT (United Kingdom); Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom); Lincoln School of Computer Science, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS (United Kingdom); Joint Department of Physics, Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey, SM2 5PT (United Kingdom)

    2011-11-15

    Purpose: The purpose of this work was to investigate the use of an experimental complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) for tracking of moving fiducial markers during radiotherapy. Methods: The APS has an active area of 5.4 x 5.4 cm and maximum full frame read-out rate of 20 frame s{sup -1}, with the option to read out a region-of-interest (ROI) at an increased rate. It was coupled to a 4 mm thick ZnWO4 scintillator which provided a quantum efficiency (QE) of 8% for a 6 MV x-ray treatment beam. The APS was compared with a standard iViewGT flat panel amorphous Silicon (a-Si) electronic portal imaging device (EPID), with a QE of 0.34% and a frame-rate of 2.5 frame s{sup -1}. To investigate the ability of the two systems to image markers, four gold cylinders of length 8 mm and diameter 0.8, 1.2, 1.6, and 2 mm were placed on a motion-platform. Images of the stationary markers were acquired using the APS at a frame-rate of 20 frame s{sup -1}, and a dose-rate of 143 MU min{sup -1} to avoid saturation. EPID images were acquired at the maximum frame-rate of 2.5 frame s{sup -1}, and a reduced dose-rate of 19 MU min{sup -1} to provide a similar dose per frame to the APS. Signal-to-noise ratio (SNR) of the background signal and contrast-to-noise ratio (CNR) of the marker signal relative to the background were evaluated for both imagers at doses of 0.125 to 2 MU. Results: Image quality and marker visibility was found to be greater in the APS with SNR {approx}5 times greater than in the EPID and CNR up to an order of magnitude greater for all four markers. To investigate the ability to image and track moving markers the motion-platform was moved to simulate a breathing cycle with period 6 s, amplitude 20 mm and maximum speed 13.2 mm s{sup -1}. At the minimum integration time of 50 ms a tracking algorithm applied to the APS data found all four markers with a success rate of {>=}92% and positional error {<=}90 {mu}m. At an integration time of 400

  8. Imaging of Ra-223 with a small-pixel CdTe detector

    Science.gov (United States)

    Scuffham, J. W.; Pani, S.; Seller, P.; Sellin, P. J.; Veale, M. C.; Wilson, M. D.; Cernik, R. J.

    2015-01-01

    Ra-223 Dichloride (Xofigo™) is a promising new radiopharmaceutical offering survival benefit and palliation of painful bone metastases in patients with hormone-refractory prostate cancer [1]. The response to radionuclide therapy and toxicity are directly linked to the absorbed radiation doses to the tumour and organs at risk respectively. Accurate dosimetry necessitates quantitative imaging of the biodistribution and kinetics of the radiopharmaceutical. Although primarily an alpha-emitter, Ra-223 also has some low-abundance X-ray and gamma emissions, which enable imaging of the biodistribution in the patient. However, the low spectral resolution of conventional gamma camera detectors makes in-vivo imaging of Ra-223 challenging. In this work, we present spectra and image data of anthropomorphic phantoms containing Ra-223 acquired with a small-pixel CdTe detector (HEXITEC) [2] with a pinhole collimator. Comparison is made with similar data acquired using a clinical gamma camera. The results demonstrate the advantages of the solid state detector in terms of scatter rejection and quantitative accuracy of the images. However, optimised collimation is needed in order for the sensitivity to rival current clinical systems. As different dosage levels and administration regimens for this drug are explored in current clinical trials, there is a clear need to develop improved imaging technologies that will enable personalised treatments to be designed for patients.

  9. Fast atmospheric correction algorithm based on the darkest pixel approach for retrieving the aerosol optical thickness: comparison with in-situ AOT measurements

    Science.gov (United States)

    Themistocleous, Kyriacos; Hadjimitsis, Diofantos G.; Alexakis, Dimitrios

    2011-11-01

    Darkest pixel atmospheric correction is the simplest and fully image-based correction method. This paper presents an overview of a proposed 'fast atmospheric correction algorithm' developed at MATLAB based on the RT equation basics and the darkest pixel approach. The task is to retrieve the aerosol optical thickness (AOT) from the application of this atmospheric correction. The effectiveness of this algorithm is performed by comparing the AOT values from the algorithm with those measured in-situ both from MICROTOPS II hand-held sunphotometer and the CIMEL sunphotometer (AERONET).

  10. Comparison of computation time and image quality between full-parallax 4G-pixels CGHs calculated by the point cloud and polygon-based method

    Science.gov (United States)

    Nakatsuji, Noriaki; Matsushima, Kyoji

    2017-03-01

    Full-parallax high-definition CGHs composed of more than billion pixels were so far created only by the polygon-based method because of its high performance. However, GPUs recently allow us to generate CGHs much faster by the point cloud. In this paper, we measure computation time of object fields for full-parallax high-definition CGHs, which are composed of 4 billion pixels and reconstruct the same scene, by using the point cloud with GPU and the polygon-based method with CPU. In addition, we compare the optical and simulated reconstructions between CGHs created by these techniques to verify the image quality.

  11. Object-based method outperforms per-pixel method for land cover classification in a protected area of the Brazilian Atlantic rainforest region

    NARCIS (Netherlands)

    Francischinelli Rittl, T.; Cooper, M.; Heck, R.J.; Ballester, V.R.

    2013-01-01

    Conventional image classification based on pixels hinders the possibilities to obtain information contained in images, while modern object-based classification methods increase the acquisition of information about the object and the context in which it is inserted in the image. The objective of this

  12. Measurement results of a 12 μm pixel size microbolometer array based on a novel thermally isolating structure using a 17 μm ROIC

    Science.gov (United States)

    Muckensturm, K.-M.; Weiler, D.; Hochschulz, F.; Busch, C.; Geruschke, T.; Wall, S.; Heß, J.; Würfel, D.; Lerch, R.; Vogt, H.

    2016-05-01

    In this paper a novel concept for the fabrication of highly sensitive uncooled microbolometers is presented. The approach is based on the realization of thermal isolation and simultaneous electrical contacting of the microbolometers by means of sufficiently long and thin coated nanotubes, which can be fabricated by post processing on top of CMOS wafers comprising the ROIC. Thus, the effective area of the absorption layer is maximized at a given pixel size, as lateral legs, which have been the main component of the thermal isolation commonly, are completely omitted. The resulting thermal conductivity can be tuned independently from the pixel size by varying the geometry and structuring of the nanotubes. Based on test structures the nanotube microbolometers are characterized with respect to electro-optical and mechanical properties. The focus in this paper is on nanotube microbolometers with a pixel size of 12 μm.

  13. Seismic zonation of Port-Au-Prince using pixel- and object-based imaging analysis methods on ASTER GDEM

    Science.gov (United States)

    Yong, Alan; Hough, Susan E.; Cox, Brady R.; Rathje, Ellen M.; Bachhuber, Jeff; Dulberg, Ranon; Hulslander, David; Christiansen, Lisa; and Abrams, Michael J.

    2011-01-01

    We report about a preliminary study to evaluate the use of semi-automated imaging analysis of remotely-sensed DEM and field geophysical measurements to develop a seismic-zonation map of Port-au-Prince, Haiti. For in situ data, VS30 values are derived from the MASW technique deployed in and around the city. For satellite imagery, we use an ASTER GDEM of Hispaniola. We apply both pixel- and object-based imaging methods on the ASTER GDEM to explore local topography (absolute elevation values) and classify terrain types such as mountains, alluvial fans and basins/near-shore regions. We assign NEHRP seismic site class ranges based on available VS30 values. A comparison of results from imagery-based methods to results from traditional geologic-based approaches reveals good overall correspondence. We conclude that image analysis of RS data provides reliable first-order site characterization results in the absence of local data and can be useful to refine detailed site maps with sparse local data.

  14. Seismic-zonation of Port-au-Prince using pixel- and object-based imaging analysis methods on ASTER GDEM

    Science.gov (United States)

    Yong, A.; Hough, S.E.; Cox, B.R.; Rathje, E.M.; Bachhuber, J.; Dulberg, R.; Hulslander, D.; Christiansen, L.; Abrams, M.J.

    2011-01-01

    We report about a preliminary study to evaluate the use of semi-automated imaging analysis of remotely-sensed DEM and field geophysical measurements to develop a seismic-zonation map of Port-au-Prince, Haiti. For in situ data, Vs30 values are derived from the MASW technique deployed in and around the city. For satellite imagery, we use an ASTER GDEM of Hispaniola. We apply both pixel- and object-based imaging methods on the ASTER GDEM to explore local topography (absolute elevation values) and classify terrain types such as mountains, alluvial fans and basins/near-shore regions. We assign NEHRP seismic site class ranges based on available Vs30 values. A comparison of results from imagery-based methods to results from traditional geologic-based approaches reveals good overall correspondence. We conclude that image analysis of RS data provides reliable first-order site characterization results in the absence of local data and can be useful to refine detailed site maps with sparse local data. ?? 2011 American Society for Photogrammetry and Remote Sensing.

  15. A compact 64-pixel CsI(T1)/Si PIN photodiode imaging module with IC readout

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Gregory J.; Choong, Woon-Seng; Moses, William W.; Derenzo, Stephen E.; Holland, Stephen E.; Pedrali-Noy, Marzio; Krieger, Brad; Mandelli, Emanuele; Meddeler, Gerrit; Wang, Nadine W.

    2001-08-09

    We characterize the performance of a complete 64-pixel compact gamma camera imaging module consisting of optically isolated 3 mm 3 mm 5 mm CsI(Tl) crystals coupled to a custom array of low-noise Si PIN photodiodes read out by a custom IC. At 50 V bias the custom 64-pixel photodiode arrays demonstrate an average leakage current of 28 pA per 3 mm 3 mm pixel, a 98.5 percent yield of pixels with <100 pA leakage, and a quantum efficiency of about 80 percent for 540 nm CsI(Tl) scintillation photons. The custom 64-channel readout IC uses low-noise preamplifiers, shaper amplifiers, and a winner-take-all (WTA) multiplexer. The IC demonstrates maximum gain of 120 mV / 1000 e-, the ability to select the largest input signal in less than 150 ns, and low electronic noise at 8 ms peaking time ranging from 25 e- rms (unloaded) to an estimated 180 e- rms (photodiode load of 3 pF, 50 pA). At room temperature a complete 64-pixel detector module employing a custom photodiode array and readout IC demonstrates an average energy resolution of 23.4 percent fwhm and an intrinsic spatial resolution of 3.3 mm fwhm for the 140 keV emissions of 99mTc. Construction of an array of such imaging modules is straightforward, hence this technology shows strong potential for numerous compact gamma camera applications, including scintimammography.

  16. [Estimation of sparse vegetation coverage in arid region based on hyperspectral mixed pixel decomposition].

    Science.gov (United States)

    Li, Xiao-Song; Gao, Zhi-Hai; Li, Zeng-Yuan; Bai, Li-Na; Wang, Beng-Yu

    2010-01-01

    Based on Hyperion hyperspectral image data, the image-derived shifting sand, false-Gobi spectra, and field-measured sparse vegetation spectra were taken as endmembers, and the sparse vegetation coverage (linear spectral mixture model (LSMM) and non-constrained LSMM, respectively. The results showed that the sparse vegetation fraction based on fully constrained LSMM described the actual sparse vegetation distribution. The differences between sparse vegetation fraction and field-measured vegetation coverage were less than 5% for all samples, and the RMSE was 3.0681. However, the sparse vegetation fraction based on non-constrained LSMM was lower than the field-measured vegetation coverage obviously, and the correlation between them was poor, with a low R2 of 0.5855. Compared with McGwire's corresponding research, the sparse vegetation coverage estimation in this study was more accurate and reliable, having expansive prospect for application in the future.

  17. A pixel based regeneration index using time series similarity and spatial context

    NARCIS (Netherlands)

    Lhermitte, S.; Verbesselt, J.; Verstraeten, W.W.; Coppin, P.

    2010-01-01

    Although the regeneration index based on control plots provides a valuable tool to quantify fire impact and subsequent vegetation regrowth, the practical implementation at large scale levels remains limited due to the need for detailed reference maps. The objective of this research therefore was the

  18. A high resolution, high frame rate detector based on a microchannel plate read out with the Medipix2 counting CMOS pixel chip.

    CERN Document Server

    Mikulec, Bettina; McPhate, J B; Tremsin, A S; Siegmund, O H W; Clark, Allan G; CERN. Geneva

    2005-01-01

    The future of ground-based optical astronomy lies with advancements in adaptive optics (AO) to overcome the limitations that the atmosphere places on high resolution imaging. A key technology for AO systems on future very large telescopes are the wavefront sensors (WFS) which detect the optical phase error and send corrections to deformable mirrors. Telescopes with >30 m diameters will require WFS detectors that have large pixel formats (512x512), low noise (<3 e-/pixel) and very high frame rates (~1 kHz). These requirements have led to the idea of a bare CMOS active pixel device (the Medipix2 chip) functioning in counting mode as an anode with noiseless readout for a microchannel plate (MCP) detector and at 1 kHz continuous frame rate. First measurement results obtained with this novel detector are presented both for UV photons and beta particles.

  19. Evaluation of pixel-wise geometric constraint-based phase-unwrapping method for low signal-to-noise-ratio (SNR) phase

    Science.gov (United States)

    An, Yatong; Liu, Ziping; Zhang, Song

    2016-12-01

    This paper evaluates the robustness of our recently proposed geometric constraint-based phase-unwrapping method to unwrap a low-signal-to-noise ratio (SNR) phase. Instead of capturing additional images for absolute phase unwrapping, the new phase-unwrapping algorithm uses geometric constraints of the digital fringe projection (DFP) system to create a virtual reference phase map to unwrap the phase pixel by pixel. Both simulation and experimental results demonstrate that this new phase-unwrapping method can even successfully unwrap low-SNR phase maps that bring difficulties for conventional multi-frequency phase-unwrapping methods.

  20. Radiation-hard Active Pixel Sensors for HL-LHC Detector Upgrades based on HV-CMOS Technology

    CERN Document Server

    Miucci, A; Hemperek, T.; Hügging, F.; Krüger, H.; Obermann, T.; Wermes, N.; Garcia-Sciveres, M.; Backhaus, M.; Capeans, M.; Feigl, S.; Nessi, M.; Pernegger, H.; Ristic, B.; Gonzalez-Sevilla, S.; Ferrere, D.; Iacobucci, G.; Rosa, A.La; Muenstermann, D.; George, M.; Grosse-Knetter, J.; Quadt, A.; Rieger, J.; Weingarten, J.; Bates, R.; Blue, A.; Buttar, C.; Hynds, D.; Kreidl, C.; Peric, I.; Breugnon, P.; Pangaud, P.; Godiot-Basolo, S.; Fougeron, D.; Bompard, F.; Clemens, J.C.; Liu, J; Barbero, M.; Rozanov, A

    2014-01-01

    Luminosity upgrades are discussed for the LHC (HL-LHC) which would make updates to the detectors necessary, requiring in particular new, even more radiation-hard and granular, sensors for the inner detector region. 1Corresponding author. c CERN 2014, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl. Any further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation and DOI. doi:10.1088/1748-0221/9/05/C050642014 JINST 9 C05064 A proposal for the next generation of inner detectors is based on HV-CMOS: a new family of silicon sensors based on commercial high-voltage CMOS technology, which enables the fabrication of part of the pixel electronics inside the silicon substrate itself. The main advantages of this technology with respect to the standard silicon sensor technology are: low material budget, fast charge collection time, high radiation tolerance, low cost and operation a...

  1. Object-Based Classification as an Alternative Approach to the Traditional Pixel-Based Classification to Identify Potential Habitat of the Grasshopper Sparrow

    Science.gov (United States)

    Jobin, Benoît; Labrecque, Sandra; Grenier, Marcelle; Falardeau, Gilles

    2008-01-01

    The traditional method of identifying wildlife habitat distribution over large regions consists of pixel-based classification of satellite images into a suite of habitat classes used to select suitable habitat patches. Object-based classification is a new method that can achieve the same objective based on the segmentation of spectral bands of the image creating homogeneous polygons with regard to spatial or spectral characteristics. The segmentation algorithm does not solely rely on the single pixel value, but also on shape, texture, and pixel spatial continuity. The object-based classification is a knowledge base process where an interpretation key is developed using ground control points and objects are assigned to specific classes according to threshold values of determined spectral and/or spatial attributes. We developed a model using the eCognition software to identify suitable habitats for the Grasshopper Sparrow, a rare and declining species found in southwestern Québec. The model was developed in a region with known breeding sites and applied on other images covering adjacent regions where potential breeding habitats may be present. We were successful in locating potential habitats in areas where dairy farming prevailed but failed in an adjacent region covered by a distinct Landsat scene and dominated by annual crops. We discuss the added value of this method, such as the possibility to use the contextual information associated to objects and the ability to eliminate unsuitable areas in the segmentation and land cover classification processes, as well as technical and logistical constraints. A series of recommendations on the use of this method and on conservation issues of Grasshopper Sparrow habitat is also provided.

  2. Traditional gamma cameras are preferred.

    Science.gov (United States)

    DePuey, E Gordon

    2016-08-01

    Although the new solid-state dedicated cardiac cameras provide excellent spatial and energy resolution and allow for markedly reduced SPECT acquisition times and/or injected radiopharmaceutical activity, they have some distinct disadvantages compared to traditional sodium iodide SPECT cameras. They are expensive. Attenuation correction is not available. Cardio-focused collimation, advantageous to increase depth-dependent resolution and myocardial count density, accentuates diaphragmatic attenuation and scatter from subdiaphragmatic structures. Although supplemental prone imaging is therefore routinely advised, many patients cannot tolerate it. Moreover, very large patients cannot be accommodated in the solid-state camera gantries. Since data are acquired simultaneously with an arc of solid-state detectors around the chest, no temporally dependent "rotating" projection images are obtained. Therefore, patient motion can be neither detected nor corrected. In contrast, traditional sodium iodide SPECT cameras provide rotating projection images to allow technologists and physicians to detect and correct patient motion and to accurately detect the position of soft tissue attenuators and to anticipate associated artifacts. Very large patients are easily accommodated. Low-dose x-ray attenuation correction is widely available. Also, relatively inexpensive low-count density software is provided by many vendors, allowing shorter SPECT acquisition times and reduced injected activity approaching that achievable with solid-state cameras.

  3. Spatial clustering of pixels of a multispectral image

    Energy Technology Data Exchange (ETDEWEB)

    Conger, James Lynn

    2014-08-19

    A method and system for clustering the pixels of a multispectral image is provided. A clustering system computes a maximum spectral similarity score for each pixel that indicates the similarity between that pixel and the most similar neighboring. To determine the maximum similarity score for a pixel, the clustering system generates a similarity score between that pixel and each of its neighboring pixels and then selects the similarity score that represents the highest similarity as the maximum similarity score. The clustering system may apply a filtering criterion based on the maximum similarity score so that pixels with similarity scores below a minimum threshold are not clustered. The clustering system changes the current pixel values of the pixels in a cluster based on an averaging of the original pixel values of the pixels in the cluster.

  4. Spatial clustering of pixels of a multispectral image

    Science.gov (United States)

    Conger, James Lynn

    2014-08-19

    A method and system for clustering the pixels of a multispectral image is provided. A clustering system computes a maximum spectral similarity score for each pixel that indicates the similarity between that pixel and the most similar neighboring. To determine the maximum similarity score for a pixel, the clustering system generates a similarity score between that pixel and each of its neighboring pixels and then selects the similarity score that represents the highest similarity as the maximum similarity score. The clustering system may apply a filtering criterion based on the maximum similarity score so that pixels with similarity scores below a minimum threshold are not clustered. The clustering system changes the current pixel values of the pixels in a cluster based on an averaging of the original pixel values of the pixels in the cluster.

  5. Development of SOI pixel detector in Cracow

    CERN Document Server

    Bugiel, Szymon; Glab, Sebastian; Idzik, Marek; Moron, Jakub; Kapusta, Piotr Julian; Kucewicz, Wojciech; Turala, Michal

    2015-01-01

    This paper presents the design of a new monolithic Silicon-On-Insulator pixel sensor in $200~nm$ SOI CMOS technology. The main application of the proposed pixel detector is the spectroscopy, but it can also be used for the minimum ionizing particle (MIP) tracking in particle physics experiments. For this reason few different versions of pixel cells are developed: a source-follower based pixel for tracking, a low noise pixel with preamplifier for spectroscopy, and a self-triggering pixel for time and amplitude measurements. In addition the design of a Successive Approximation Register Analog-to-Digital Converter (SAR ADC) is also presented. A 10-bit SAR ADC is developed for spectroscopic measurements and a lower resolution 6-bit SAR ADC is integrated in the pixel matrix as a column ADC, for tracking applications.

  6. Biodistribution and planar gamma camera imaging of {sup 123}I- and {sup 131}I-labeled F(ab'){sub 2} and Fab fragments of monoclonal antibody 14C5 in nude mice bearing an A549 lung tumor

    Energy Technology Data Exchange (ETDEWEB)

    Burvenich, Ingrid J.G. [Laboratory of Radiopharmacy, University of Ghent, B-9000 Ghent (Belgium)]. E-mail: ingrid.burvenich@ugent.be; Schoonooghe, Steve [Department of Biomedical Research, Flanders Institute of Biotechnology (VIB), University of Ghent, B-9000 Ghent (Belgium); Blanckaert, Peter [Laboratory of Radiopharmacy, University of Ghent, B-9000 Ghent (Belgium); Bacher, Klaus [Department of Medical Physics and Radiation Protection, Ghent University, B-9000 Ghent (Belgium); Vervoort, Liesbet [Laboratory of Radiopharmacy, University of Ghent, B-9000 Ghent (Belgium); Coene, Elisabeth [N. Goormaghtigh Institute of Pathology, Ghent University, B-9000 Ghent (Belgium); Mertens, Nico [Department of Biomedical Research, Flanders Institute of Biotechnology (VIB), University of Ghent, B-9000 Ghent (Belgium); Vos, Filip de [Laboratory of Radiopharmacy, University of Ghent, B-9000 Ghent (Belgium); Slegers, Guido [Laboratory of Radiopharmacy, University of Ghent, B-9000 Ghent (Belgium)

    2007-04-15

    Detection of antigen 14C5, involved in substrate adhesion and highly expressed on the membrane of many carcinomas, including lung cancer, provides important diagnostic information that can influence patient management. The aim of this study was to evaluate the biodistribution and planar gamma camera imaging characteristics of radioiodinated F(ab'){sub 2} and Fab fragments of monoclonal antibody (mAb) 14C5 in tumor-bearing mice. Methods: F(ab'){sub 2} and Fab 14C5 fragments were radioiodinated using the Iodo-Gen method. In vitro stability, binding specificity and affinity of {sup 125}I-labeled 14C5 fragments were studied in A549 lung carcinoma cells. Biodistribution, blood clearance and tumor-targeting characteristics of {sup 131}I-labeled 14C5 fragments and intact mAb 14C5 were studied in Swiss nu/nu mice bearing A549 lung carcinoma tumors. Planar gamma imaging illustrated the potential use of these {sup 123}I-labeled 14C5 fragments for radioimmunodetection (RID). Results: Saturation binding experiments showed highest affinity for {sup 125}I-labeled F(ab'){sub 2} fragments (K {sub d}=0.37{+-}0.10 nmol/L) and lowest affinity for {sup 125}I-labeled Fab fragments (K {sub d}=2.25{+-}0.44 nmol/L). Blood clearance studies showed that the alpha half-life (t1/2{alpha}) value for Fab, F(ab'){sub 2} and mAb 14C5 was 14.9, 21 and 118 min, respectively. The beta half-life t1/2{beta} value for Fab, F(ab'){sub 2} and mAb 14C5 was 439, 627 and 4067 min, respectively. {sup 131}I-Fab fragments showed highest tumor uptake 3 h after injection (2.4{+-}0.8 %ID/g), {sup 131}I-labeled F(ab'){sub 2} showed highest tumor uptake 6 h after injection (4.7{+-}0.7 %ID/g) and for {sup 131}I-labeled mAb highest tumor uptake was observed at 24 h (10.7{+-}2.3 %ID/g). In planar gamma imaging, both labeled fragments gave better tumor-to-background contrast than {sup 123}I-mAb 14C5. Conclusion: Fab and F(ab'){sub 2} fragments derived from intact mAb 14C5 have

  7. Comparison of Advanced Pixel Based (ANN and SVM and Object-Oriented Classification Approaches Using Landsat-7 Etm+ Data

    Directory of Open Access Journals (Sweden)

    Prasun Kumar Gupta

    2010-08-01

    Full Text Available In this study, the pixel-based and object-oriented image classification approaches were used for identifying different land use types in Karnal district. Imagery from Landsat-7 ETM with 6 spectral bands was used to perform the image classification.Ground truth data were collected from the available maps, personal knowledge and communication with the local people. In order to prepare land use map different approaches: Artificial Neural Network(ANN and Support Vector Machine (SVM were used. For performing object oriented classification eCognition software was used. During the object oriented classification, in first step several differentsets of parameters were used for image segmentation and in second step nearest neighbor classifier was used for classification. Outcome from the classification works show that the object-oriented approach gave more accurate results (including higher producer’s and user’s accuracy for most of the land cover classes than those achieved by pixelbased classification algorithms. It is also observed that ANN performed better as compared to SVM classification approach.

  8. Multistep Lattice-Voxel method utilizing lattice function for Monte-Carlo treatment planning with pixel based voxel model.

    Science.gov (United States)

    Kumada, H; Saito, K; Nakamura, T; Sakae, T; Sakurai, H; Matsumura, A; Ono, K

    2011-12-01

    Treatment planning for boron neutron capture therapy generally utilizes Monte-Carlo methods for calculation of the dose distribution. The new treatment planning system JCDS-FX employs the multi-purpose Monte-Carlo code PHITS to calculate the dose distribution. JCDS-FX allows to build a precise voxel model consisting of pixel based voxel cells in the scale of 0.4×0.4×2.0 mm(3) voxel in order to perform high-accuracy dose estimation, e.g. for the purpose of calculating the dose distribution in a human body. However, the miniaturization of the voxel size increases calculation time considerably. The aim of this study is to investigate sophisticated modeling methods which can perform Monte-Carlo calculations for human geometry efficiently. Thus, we devised a new voxel modeling method "Multistep Lattice-Voxel method," which can configure a voxel model that combines different voxel sizes by utilizing the lattice function over and over. To verify the performance of the calculation with the modeling method, several calculations for human geometry were carried out. The results demonstrated that the Multistep Lattice-Voxel method enabled the precise voxel model to reduce calculation time substantially while keeping the high-accuracy of dose estimation.

  9. Mapping trees outside forests using high-resolution aerial imagery: a comparison of pixel- and object-based classification approaches.

    Science.gov (United States)

    Meneguzzo, Dacia M; Liknes, Greg C; Nelson, Mark D

    2013-08-01

    Discrete trees and small groups of trees in nonforest settings are considered an essential resource around the world and are collectively referred to as trees outside forests (ToF). ToF provide important functions across the landscape, such as protecting soil and water resources, providing wildlife habitat, and improving farmstead energy efficiency and aesthetics. Despite the significance of ToF, forest and other natural resource inventory programs and geospatial land cover datasets that are available at a national scale do not include comprehensive information regarding ToF in the United States. Additional ground-based data collection and acquisition of specialized imagery to inventory these resources are expensive alternatives. As a potential solution, we identified two remote sensing-based approaches that use free high-resolution aerial imagery from the National Agriculture Imagery Program (NAIP) to map all tree cover in an agriculturally dominant landscape. We compared the results obtained using an unsupervised per-pixel classifier (independent component analysis-[ICA]) and an object-based image analysis (OBIA) procedure in Steele County, Minnesota, USA. Three types of accuracy assessments were used to evaluate how each method performed in terms of: (1) producing a county-level estimate of total tree-covered area, (2) correctly locating tree cover on the ground, and (3) how tree cover patch metrics computed from the classified outputs compared to those delineated by a human photo interpreter. Both approaches were found to be viable for mapping tree cover over a broad spatial extent and could serve to supplement ground-based inventory data. The ICA approach produced an estimate of total tree cover more similar to the photo-interpreted result, but the output from the OBIA method was more realistic in terms of describing the actual observed spatial pattern of tree cover.

  10. ATLAS IBL Pixel Upgrade

    CERN Document Server

    La Rosa, A

    2011-01-01

    The upgrade for ATLAS detector will undergo different phase towards super-LHC. The first upgrade for the Pixel detector will consist of the construction of a new pixel layer which will be installed during the first shutdown of the LHC machine (LHC phase-I upgrade). The new detector, called Insertable B-Layer (IBL), will be inserted between the existing pixel detector and a new (smaller radius) beam-pipe at a radius of 3.3 cm. The IBL will require the development of several new technologies to cope with increase of radiation or pixel occupancy and also to improve the physics performance which will be achieved by reducing the pixel size and of the material budget. Three different promising sensor technologies (planar-Si, 3D-Si and diamond) are currently under investigation for the pixel detector. An overview of the project with particular emphasis on pixel module is presented in this paper

  11. Novel WLL Architecture Based on Color Pixel Multiple Access Implemented on a Terrestrial Video Network as the Overlay

    DEFF Research Database (Denmark)

    Sanyal, Rajarshi; Cianca, Ernestina; Prasad, Ramjee

    2013-01-01

    for conveying data symbols from one end to other. The big question is: Is it feasible to implement color synthesized by the video systems for the purpose of telecommunications? In this paper we propose the ‘Color Pixel Multiple Access’ scheme for the radio access network and Color Pixel Multiplexing for core...... network, by implementing electronic color as a tool for addressing and bearing data overhead. The present day video systems that can generate millions of colors, in its electronic form have been utilized to set up a wireless network, serving mobile stations or computers as its nodes. The state of the art...

  12. Adaptive pseudo-color enhancement method of weld radiographic images based on HSI color space and self-transformation of pixels

    Science.gov (United States)

    Jiang, Hongquan; Zhao, Yalin; Gao, Jianmin; Gao, Zhiyong

    2017-06-01

    The radiographic testing (RT) image of a steam turbine manufacturing enterprise has the characteristics of low gray level, low contrast, and blurriness, which lead to a substandard image quality. Moreover, it is not conducive for human eyes to detect and evaluate defects. This study proposes an adaptive pseudo-color enhancement method for weld radiographic images based on the hue, saturation, and intensity (HSI) color space and the self-transformation of pixels to solve these problems. First, the pixel's self-transformation is performed to the pixel value of the original RT image. The function value after the pixel's self-transformation is assigned to the HSI components in the HSI color space. Thereafter, the average intensity of the enhanced image is adaptively adjusted to 0.5 according to the intensity of the original image. Moreover, the hue range and interval can be adjusted according to personal habits. Finally, the HSI components after the adaptive adjustment can be transformed to display in the red, green, and blue color space. Numerous weld radiographic images from a steam turbine manufacturing enterprise are used to validate the proposed method. The experimental results show that the proposed pseudo-color enhancement method can improve image definition and make the target and background areas distinct in weld radiographic images. The enhanced images will be more conducive for defect recognition. Moreover, the image enhanced using the proposed method conforms to the human eye visual properties, and the effectiveness of defect recognition and evaluation can be ensured.

  13. Penrose Pixels for Super-Resolution.

    Science.gov (United States)

    Ben-Ezra, M; Lin, Zhouchen; Wilburn, Bennett; Zhang, Wei

    2011-07-01

    We present a novel approach to reconstruction-based super-resolution that uses aperiodic pixel tilings, such as a Penrose tiling or a biological retina, for improved performance. To this aim, we develop a new variant of the well-known error back projection super-resolution algorithm that makes use of the exact detector model in its back projection operator for better accuracy. Pixels in our model can vary in shape and size, and there may be gaps between adjacent pixels. The algorithm applies equally well to periodic or aperiodic pixel tilings. We present analysis and extensive tests using synthetic and real images to show that our approach using aperiodic layouts substantially outperforms existing reconstruction-based algorithms for regular pixel arrays. We close with a discussion of the feasibility of manufacturing CMOS or CCD chips with pixels arranged in Penrose tilings.

  14. Dead pixel replacement in LWIR microgrid polarimeters.

    Science.gov (United States)

    Ratliff, Bradley M; Tyo, J Scott; Boger, James K; Black, Wiley T; Bowers, David L; Fetrow, Matthew P

    2007-06-11

    LWIR imaging arrays are often affected by nonresponsive pixels, or "dead pixels." These dead pixels can severely degrade the quality of imagery and often have to be replaced before subsequent image processing and display of the imagery data. For LWIR arrays that are integrated with arrays of micropolarizers, the problem of dead pixels is amplified. Conventional dead pixel replacement (DPR) strategies cannot be employed since neighboring pixels are of different polarizations. In this paper we present two DPR schemes. The first is a modified nearest-neighbor replacement method. The second is a method based on redundancy in the polarization measurements.We find that the redundancy-based DPR scheme provides an order-of-magnitude better performance for typical LWIR polarimetric data.

  15. Evaluation of Sub-Pixel Cloud Noises on MODIS Daily Spectral Indices Based on in situ Measurements

    Directory of Open Access Journals (Sweden)

    Kenlo Nishida Nasahara

    2011-08-01

    Full Text Available Cloud contamination is one of the severest problems for the time-series analysis of optical remote sensing data such as vegetation phenology detection. Sub-pixel clouds are especially difficult to identify and remove. It is important for accuracy improvement in various terrestrial remote sensing applications to clarify the influence of these residual clouds on spectral vegetation indices. This study investigated the noises caused by residual sub-pixel clouds on several frequently-used spectral indices (NDVI, EVI, EVI2, NDWI, and NDII by using in situ spectral data and sky photographs at the satellite overpass time. We conducted in situ continuous observation at a Japanese deciduous forest for over a year and compared the MODIS spectral indices with the cloud-free in situ spectral indices. Our results revealed that residual sub-pixel clouds potentially contaminated about 40% of the MODIS data after cloud screening by the state flag of MOD09 product. These residual clouds significantly decreased NDVI values during the leaf growing season. However, such noises did not appear in the other indices. This result was thought to be caused by the different combination of wavelengths among spectral indices. Our results suggested that the noises by residual sub-pixel clouds can be reduced by using EVI, NDWI, or NDII in place of NDVI.

  16. Object-Based Method Outperforms Per-Pixel Method for Land Cover Classification in a Protected Area of the Brazilian Atlantic Rainforest Region

    Institute of Scientific and Technical Information of China (English)

    T.RITTL; M.COOPER; R.J.HECK; M.V.R.BALLESTER

    2013-01-01

    Conventional image classification based on pixels hinders the possibilities to obtain information contained in images,while modern object-based classification methods increase the acquisition of information about the object and the context in which it is inserted in the image.The objective of this study was to investigate the performance of different classification methods for land cover mapping in the vicinity of the Alto Ribeira Tourist State Park,a Brazilian Atlantic rainforest area.Two classification methods were tested,including i) a hybrid per-pixel classification using the image processing software ERDAS Imagine version 9.1 and ii) an object-based classification using the software eCognition version 5.In the first method,six different classes were established,while in the second method,another two classes were established in addition to the six classes in the first method.Accuracy assessment of the classification results presented showed that the object-based classification with a Kappa index value of 0.8687 outperformed the per-pixel classification with a Kappa index value of 0.2224.Application of the user's knowledge during the object-based classification process achieved the desired quality;therefore,the use of inter-relationships between objects,superclasses,subclasses,and neighboring classes were critical to improving the efficiency of land cover classification.

  17. Serial Pixel Analog-to-Digital Converter

    Energy Technology Data Exchange (ETDEWEB)

    Larson, E D

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and “one-hot” counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  18. Evaluation of 320x240 pixel LEC GaAs Schottky barrier X-ray imaging arrays, hybridized to CMOS readout circuit based on charge integration

    CERN Document Server

    Irsigler, R; Alverbro, J; Borglind, J; Froejdh, C; Helander, P; Manolopoulos, S; O'Shea, V; Smith, K

    1999-01-01

    320x240 pixels GaAs Schottky barrier detector arrays were fabricated, hybridized to silicon readout circuits, and subsequently evaluated. The detector chip was based on semi-insulating LEC GaAs material. The square shaped pixel detector elements were of the Schottky barrier type and had a pitch of 38 mu m. The GaAs wafers were thinned down prior to the fabrication of the ohmic back contact. After dicing, the chips were indium bump, flip-chip bonded to CMOS readout circuits based on charge integration, and finally evaluated. A bias voltage between 50 and 100 V was sufficient to operate the detector. Results on I-V characteristics, noise behaviour and response to X-ray radiation are presented. Images of various objects and slit patterns were acquired by using a standard dental imaging X-ray source. The work done was a part of the XIMAGE project financed by the European Community (Brite-Euram). (author)

  19. Rapid-acquisition myocardial perfusion scintigraphy (MPS) on a novel gamma camera using multipinhole collimation and miniaturized cadmium-zinc-telluride (CZT) detectors: prognostic value and diagnostic accuracy in a 'real-world' nuclear cardiology service.

    Science.gov (United States)

    Chowdhury, F U; Vaidyanathan, S; Bould, M; Marsh, J; Trickett, C; Dodds, K; Clark, T P R; Sapsford, R J; Dickinson, C J; Patel, C N; Thorley, P J

    2014-03-01

    To study the prognostic value of rapid-acquisition adenosine stress-rest myocardial perfusion scintigraphy (MPS) on a gamma camera using multipinhole collimation and cadmium-zinc-telluride (CZT) detectors. The secondary aim was to assess the diagnostic accuracy of the technique compared with invasive coronary angiography. Retrospective analysis of 1109 consecutive patients undergoing MPS in a routine clinical setting on a high-efficiency multipinhole gamma camera. MPS acquisition, performed with a standard injection of 550 MBq of (99m)Tc-tetrofosmin, required a mean (±SD) scanning time of 322 ± 51 s. The hard cardiac event rate at a median (inter-quartile range) follow-up of 624 (552-699) days was 0.4% (95% CI 0.1-1.1) in patients with no significant perfusion abnormality versus 6.8% (95% CI 4.3-10.7%, P MPS of 84% (95% CI 74-91), 79% (95% CI 68-87), 82% (95% CI 72-89), 81% (95% CI 70-89), and 82% (95% CI 73-89), respectively. MPS performed on a CZT solid-state detector camera with multipinhole collimation is an evolutionary development that provides reliable prognostic and diagnostic information, while significantly reducing image acquisition time.

  20. Soil erosion and its correlation with vegetation cover: An assesment using multispectral imagery and pixel-based geographic information system in Gesing Sub-Watershed, Central Java, Indonesia

    Science.gov (United States)

    Dirda Gupita, Diwyacitta; Sigit Heru Murti, B. S.

    2017-01-01

    Soil erosion in caused by five factors: rainfall erosivity, soil erodibility, slope and slope length, crop management, and land conservation practices. In theory, vegetation as one of the affecting factors has inversed correlation with soil erosion. This research is aimed to: (1) model RUSLE using pixel-based GIS, and (2) prove whether or not vegetation really has the said correlation with the soil erosion that occurs in Gesing Watershed. The method used in this research is divided into two: the use of RUSLE to estimate the soil erosion rate; and the use of fractional vegetation cover (FVC) formula to estimate the vegetation density in the area. Both methods used Landsat-8 OLI imagery, which is used to extract the RUSLE parameters as well as to derive the vegetation density through NDVI, and pixel-based GIS. The mapping of soil erosion rate distribution done in this research demonstrated that pixel-based modeling is able to represent a much more detailed and logical distribution of a phenomenon. The distribution of soil erosion rate in Gesing Watershed showed that the erosion rate in this area is relatively minor. About 1425.99 hectares and 1587.57 hectares of the total area have erosion rate of 0 – 15 tons/ha/yr (very mild) and 15 – 60 tons/ha/yr (mild) respectively.

  1. SPECT and {sup 123}I-Iodolisuride ({sup 123}-I-ILIS) in extra-pyramidal syndromes. The use of different models of {gamma}-cameras; TEMP a l'{sup 123}I-Iodolisuride chez des patients presentant un syndrome extrapyramidal. Utilisation de differents modeles {gamma}-camera

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M.J.; Jannuario, C.; Santos, A.C.; Cunha, L.; Pedroso de Lima, J.J. [FMC Coimbra (Portugal); Prunier-Levilion, C.; Autret, A.; Guilloteau, D.; Besnard, J.C.; Baulieu, J.L. [Centre Hospitalier Universitaire, 37 - Tours (France); Chassat, F.; Bekhechi, D.; Marchand, J.; Mauclaire, L. [CIS bio international, CEA Saclay, 91 - Gif-sur-Yvette (France); Catela, L. [ITN, Sacavem (Portugal)

    1999-06-01

    The aim of this work was to evaluate {sup 123}I-ILIS as a radioligand of dopamine receptors in patients with extra-pyramidal diseases by using different cameras in two different centers. 45 patients were included and divided in 2 groups: group I (n=28): idiopathic Parkinson disease, group II (n=17): other extra-pyramidal syndrome. {sup 123}I-ILIS, 1.7 to 2.8 MBq/kg, was injected after informed consent. Imaging was performed with a single head camera, a dual head camera, a triple head camera and a brain dedicated annular detector. The pattern of the transverse slices containing the basal ganglia was classified according to 3 types: type 1: visible basal ganglia and invisible cortex, type 2: invisible basal ganglia and visible cortex, type 3: visible basal ganglia and cortex. Striatal/frontal cortex ratio (S/FC) was calculated from standardized, geometrical ROI's. No patient showed any undesirable effect. All SPECT images were interpretable. In group 1, 45/45 scintigraphic pattern were type 1 or 3, in group II 18/23 scintigraphic patterns were type 2 or 3. S/FC was significantly lower in group II than in group I patients. We conclude that {sup 123}I-ILIS SPECT can be performed with any conventional {gamma}-camera. It provides functional informations about the striatal dopaminergic synapse in patients with extra-pyramidal degenerative disease, and could be useful in the differential diagnosis between Parkinson disease and other extra-pyramidal syndromes. (author)

  2. Advances in Small Pixel TES-Based X-Ray Microcalorimeter Arrays for Solar Physics and Astrophysics

    Science.gov (United States)

    Bandler, S. R.; Adams, J. S.; Bailey, C. N.; Busch, S. E.; Chervenak, J. A.; Eckart, M. E.; Ewin, A. E.; Finkbeiner, F. M.; Kelley, R. L.; Kelly, D. P.; Kilbourne, C. A.; Porst, J.-P.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Wassell, E. J.

    2012-01-01

    We are developing small-pixel transition-edge-sensor (TES) for solar physics and astrophysics applications. These large format close-packed arrays are fabricated on solid silicon substrates and are designed to accommodate count-rates of up to a few hundred counts/pixel/second at a FWHM energy resolution approximately 2 eV at 6 keV. We have fabricated versions that utilize narrow-line planar and stripline wiring. We present measurements of the performance and uniformity of kilo-pixel arrays, incorporating TESs with single 65-micron absorbers on a 7s-micron pitch, as well as versions with more than one absorber attached to the TES, 4-absorber and 9-absorber "Hydras". We have also fabricated a version of this detector optimized for lower energies and lower count-rate applications. These devices have a lower superconducting transition temperature and are operated just above the 40mK heat sink temperature. This results in a lower heat capacity and low thermal conductance to the heat sink. With individual single pixels of this type we have achieved a FWHM energy resolution of 0.9 eV with 1.5 keV Al K x-rays, to our knowledge the first x-ray microcalorimeter with sub-eV energy resolution. The 4-absorber and 9-absorber versions of this type achieved FWHM energy resolutions of 1.4 eV and 2.1 eV at 1.5 keV respectively. We will discuss the application of these devices for new astrophysics mission concepts.

  3. Simulation of the expected performance of a seamless scanner for brain PET based on highly pixelated CdTe detectors.

    Science.gov (United States)

    Mikhaylova, Ekaterina; De Lorenzo, Gianluca; Chmeissani, Mokhtar; Kolstein, Machiel; Cañadas, Mario; Arce, Pedro; Calderón, Yonatan; Uzun, Dilber; Ariño, Gerard; Macias-Montero, José Gabriel; Martinez, Ricardo; Puigdengoles, Carles; Cabruja, Enric

    2014-02-01

    The aim of this work is the evaluation of the design for a nonconventional PET scanner, the voxel imaging PET (VIP), based on pixelated room-temperature CdTe detectors yielding a true 3-D impact point with a density of 450 channels/cm(3), for a total 6 336 000 channels in a seamless ring shaped volume. The system is simulated and evaluated following the prescriptions of the NEMA NU 2-2001 and the NEMA NU 4-2008 standards. Results show that the excellent energy resolution of the CdTe detectors (1.6% for 511 keV photons), together with the small voxel pitch (1 × 1 × 2 mm(3)), and the crack-free ring geometry, give the design the potential to overcome the current limitations of PET scanners and to approach the intrinsic image resolution limits set by physics. The VIP is expected to reach a competitive sensitivity and a superior signal purity with respect to values commonly quoted for state-of-the-art scintillating crystal PETs. The system can provide 14 cps/kBq with a scatter fraction of 3.95% and 21 cps/kBq with a scatter fraction of 0.73% according to NEMA NU 2-2001 and NEMA NU 4-2008, respectively. The calculated NEC curve has a peak value of 122 kcps at 5.3 kBq/mL for NEMA NU 2-2001 and 908 kcps at 1.6 MBq/mL for NEMA NU 4-2008. The proposed scanner can achieve an image resolution of ~ 1 mm full-width at half-maximum in all directions. The virtually noise-free data sample leads to direct positive impact on the quality of the reconstructed images. As a consequence, high-quality high-resolution images can be obtained with significantly lower number of events compared to conventional scanners. Overall, simulation results suggest the VIP scanner can be operated either at normal dose for fast scanning and high patient throughput, or at low dose to decrease the patient radioactivity exposure. The design evaluation presented in this work is driving the development and the optimization of a fully operative prototype to prove the feasibility of the VIP concept.

  4. Hard-X and gamma-ray imaging detector for astrophysics based on pixelated CdTe semiconductors

    Science.gov (United States)

    Gálvez, J.-L.; Hernanz, M.; Álvarez, L.; Artigues, B.; Ullán, M.; Lozano, M.; Pellegrini, G.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2016-01-01

    Stellar explosions are astrophysical phenomena of great importance and interest. Instruments with high sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators. In order to achieve the needed performance, a hard-X and gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. We present a detector module which consists of a single CdTe crystal of 12.5 × 12.5mm 2 and 2mm thick with a planar cathode and with the anode segmented in an 11x11 pixel array with a pixel pitch of 1 mm attached to the readout chip. Two possible detector module configurations are considered: the so-called Planar Transverse Field (PTF) and the Parallel Planar Field (PPF). The combination of several modules in PTF or PPF configuration will achieve the desired performance of the imaging detector. The sum energy resolution of all pixels of the CdTe module measured at 122 keV and 356 keV is 3.8% and 2% respectively, in the following operating conditions: PPF irradiation, bias voltage -500 V and temperature -10̂ C.

  5. A novel phase-unwrapping method based on pixel clustering and local surface fitting with application to Dixon water-fat MRI.

    Science.gov (United States)

    Cheng, Junying; Mei, Yingjie; Liu, Biaoshui; Guan, Jijing; Liu, Xiaoyun; Wu, Ed X; Feng, Qianjin; Chen, Wufan; Feng, Yanqiu

    2017-03-01

    To develop and evaluate a novel 2D phase-unwrapping method that works robustly in the presence of severe noise, rapid phase changes, and disconnected regions. The MR phase map usually varies rapidly in regions adjacent to wraps. In contrast, the phasors can vary slowly, especially in regions distant from tissue boundaries. Based on this observation, this paper develops a phase-unwrapping method by using a pixel clustering and local surface fitting (CLOSE) approach to exploit different local variation characteristics between the phase and phasor data. The CLOSE approach classifies pixels into easy-to-unwrap blocks and difficult-to-unwrap residual pixels first, and then sequentially performs intrablock, interblock, and residual-pixel phase unwrapping by a region-growing surface-fitting method. The CLOSE method was evaluated on simulation and in vivo water-fat Dixon data, and was compared with phase region expanding labeler for unwrapping discrete estimates (PRELUDE). In the simulation experiment, the mean error ratio by CLOSE was less than 1.50%, even in areas with signal-to-noise ratio equal to 0.5, phase changes larger than π, and disconnected regions. For 350 in vivo knee and ankle images, the water-fat swap ratio of CLOSE was 4.29%, whereas that of PRELUDE was 25.71%. The CLOSE approach can correctly unwrap phase with high robustness, and benefit MRI applications that require phase unwrapping. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  6. The pixelated detector

    CERN Multimedia

    Sutton, C

    1990-01-01

    "Collecting data as patterns of light or subatomic particles is vitally important in all the sciences. The new generation of solid-state detectors called pixel devices could transform experimental research at all levels" (4 pages).

  7. Comparison of FDG PET and positron coincidence detection imaging using a dual-head gamma camera with 5/8-inch NaI(Tl) crystals in patients with suspected body malignancies.

    Science.gov (United States)

    Boren, E L; Delbeke, D; Patton, J A; Sandler, M P

    1999-04-01

    The purpose of this study was to compare the diagnostic accuracy of fluorine-18 fluorodeoxyglucose (FDG) images obtained with (a) a dual-head coincidence gamma camera (DHC) equipped with 5/8-inch-thick NaI(Tl) crystals and parallel slit collimators and (b) a dedicated positron emission tomograph (PET) in a series of 28 patients with known or suspected malignancies. Twenty-eight patients with known or suspected malignancies underwent whole-body FDG PET imaging (Siemens, ECAT 933) after injection of approximately 10 mCi of 18F-FDG. FDG DHC images were then acquired for 30 min over the regions of interest using a dual-head gamma camera (VariCam, Elscint). The images were reconstructed in the normal mode, using photopeak/photopeak, photopeak/Compton, and Compton/photopeak coincidence events. FDG PET imaging found 45 lesions ranging in size from 1 cm to 7 cm in 28 patients. FDG DHC imaging detected 35/45 (78%) of these lesions. Among the ten lesions not seen with FDG DHC imaging, eight were less than 1.5 cm in size, and two were located centrally within the abdomen suffering from marked attenuation effects. The lesions were classified into three categories: thorax (n=24), liver (n=12), and extrahepatic abdominal (n=9). FDG DHC imaging identified 100% of lesions above 1.5 cm in the thorax group and 78% of those below 1.5 cm, for an overall total of 83%. FDG DHC imaging identified 100% of lesions above 1.5 cm, in the liver and 43% of lesions below 1.5 cm, for an overall total of 67%. FDG DHC imaging identified 78% of lesions above 1.5 cm in the extrahepatic abdominal group. There were no lesions below 1.5 cm in this group. FDG coincidence imaging using a dual-head gamma camera detected 90% of lesions greater than 1.5 cm. These data suggest that DHC imaging can be used clinically in well-defined diagnostic situations to differentiate benign from malignant lesions.

  8. Pixel-level Matching Based Multi-hypothesis Error Concealment Modes for Wireless 3D H.264/MVC Communication

    Science.gov (United States)

    El-Shafai, Walid

    2015-09-01

    3D multi-view video (MVV) is multiple video streams shot by several cameras around a single scene simultaneously. Therefore it is an urgent task to achieve high 3D MVV compression to meet future bandwidth constraints while maintaining a high reception quality. 3D MVV coded bit-streams that are transmitted over wireless network can suffer from error propagation in the space, time and view domains. Error concealment (EC) algorithms have the advantage of improving the received 3D video quality without any modifications in the transmission rate or in the encoder hardware or software. To improve the quality of reconstructed 3D MVV, we propose an efficient adaptive EC algorithm with multi-hypothesis modes to conceal the erroneous Macro-Blocks (MBs) of intra-coded and inter-coded frames by exploiting the spatial, temporal and inter-view correlations between frames and views. Our proposed algorithm adapts to 3D MVV motion features and to the error locations. The lost MBs are optimally recovered by utilizing motion and disparity matching between frames and views on pixel-by-pixel matching basis. Our simulation results show that the proposed adaptive multi-hypothesis EC algorithm can significantly improve the objective and subjective 3D MVV quality.

  9. SIFT-based dense pixel tracking on 0.35 T cine-MR images acquired during image-guided radiation therapy with application to gating optimization

    Energy Technology Data Exchange (ETDEWEB)

    Mazur, Thomas R., E-mail: tmazur@radonc.wustl.edu, E-mail: hli@radonc.wustl.edu; Fischer-Valuck, Benjamin W.; Wang, Yuhe; Yang, Deshan; Mutic, Sasa; Li, H. Harold, E-mail: tmazur@radonc.wustl.edu, E-mail: hli@radonc.wustl.edu [Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States)

    2016-01-15

    Purpose: To first demonstrate the viability of applying an image processing technique for tracking regions on low-contrast cine-MR images acquired during image-guided radiation therapy, and then outline a scheme that uses tracking data for optimizing gating results in a patient-specific manner. Methods: A first-generation MR-IGRT system—treating patients since January 2014—integrates a 0.35 T MR scanner into an annular gantry consisting of three independent Co-60 sources. Obtaining adequate frame rates for capturing relevant patient motion across large fields-of-view currently requires coarse in-plane spatial resolution. This study initially (1) investigate the feasibility of rapidly tracking dense pixel correspondences across single, sagittal plane images (with both moderate signal-to-noise and spatial resolution) using a matching objective for highly descriptive vectors called scale-invariant feature transform (SIFT) descriptors associated to all pixels that describe intensity gradients in local regions around each pixel. To more accurately track features, (2) harmonic analysis was then applied to all pixel trajectories within a region-of-interest across a short training period. In particular, the procedure adjusts the motion of outlying trajectories whose relative spectral power within a frequency bandwidth consistent with respiration (or another form of periodic motion) does not exceed a threshold value that is manually specified following the training period. To evaluate the tracking reliability after applying this correction, conventional metrics—including Dice similarity coefficients (DSCs), mean tracking errors (MTEs), and Hausdorff distances (HD)—were used to compare target segmentations obtained via tracking to manually delineated segmentations. Upon confirming the viability of this descriptor-based procedure for reliably tracking features, the study (3) outlines a scheme for optimizing gating parameters—including relative target position and a

  10. SIFT-based dense pixel tracking on 0.35 T cine-MR images acquired during image-guided radiation therapy with application to gating optimization.

    Science.gov (United States)

    Mazur, Thomas R; Fischer-Valuck, Benjamin W; Wang, Yuhe; Yang, Deshan; Mutic, Sasa; Li, H Harold

    2016-01-01

    To first demonstrate the viability of applying an image processing technique for tracking regions on low-contrast cine-MR images acquired during image-guided radiation therapy, and then outline a scheme that uses tracking data for optimizing gating results in a patient-specific manner. A first-generation MR-IGRT system-treating patients since January 2014-integrates a 0.35 T MR scanner into an annular gantry consisting of three independent Co-60 sources. Obtaining adequate frame rates for capturing relevant patient motion across large fields-of-view currently requires coarse in-plane spatial resolution. This study initially (1) investigate the feasibility of rapidly tracking dense pixel correspondences across single, sagittal plane images (with both moderate signal-to-noise and spatial resolution) using a matching objective for highly descriptive vectors called scale-invariant feature transform (SIFT) descriptors associated to all pixels that describe intensity gradients in local regions around each pixel. To more accurately track features, (2) harmonic analysis was then applied to all pixel trajectories within a region-of-interest across a short training period. In particular, the procedure adjusts the motion of outlying trajectories whose relative spectral power within a frequency bandwidth consistent with respiration (or another form of periodic motion) does not exceed a threshold value that is manually specified following the training period. To evaluate the tracking reliability after applying this correction, conventional metrics-including Dice similarity coefficients (DSCs), mean tracking errors (MTEs), and Hausdorff distances (HD)-were used to compare target segmentations obtained via tracking to manually delineated segmentations. Upon confirming the viability of this descriptor-based procedure for reliably tracking features, the study (3) outlines a scheme for optimizing gating parameters-including relative target position and a tolerable margin about this

  11. DESIGN OF DYADIC-INTEGER-COEFFICIENTS BASED BI-ORTHOGONAL WAVELET FILTERS FOR IMAGE SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION

    Directory of Open Access Journals (Sweden)

    P.B. Chopade

    2014-05-01

    Full Text Available This paper presents image super-resolution scheme based on sub-pixel image registration by the design of a specific class of dyadic-integer-coefficient based wavelet filters derived from the construction of a half-band polynomial. First, the integer-coefficient based half-band polynomial is designed by the splitting approach. Next, this designed half-band polynomial is factorized and assigned specific number of vanishing moments and roots to obtain the dyadic-integer coefficients low-pass analysis and synthesis filters. The possibility of these dyadic-integer coefficients based wavelet filters is explored in the field of image super-resolution using sub-pixel image registration. The two-resolution frames are registered at a specific shift from one another to restore the resolution lost by CCD array of camera. The discrete wavelet transform (DWT obtained from the designed coefficients is applied on these two low-resolution images to obtain the high resolution image. The developed approach is validated by comparing the quality metrics with existing filter banks.

  12. A New Image Steganography Method Based on Pixel Neighbors and 6 Most Significant Bit(MSB Compare

    Directory of Open Access Journals (Sweden)

    Mashallah Abbasi Dezfouli

    2013-11-01

    Full Text Available Today, steganography is known as an effective way to convey secret data. A wide range of techniques has been developed in this context, each seeking to improve certain problems of their own. The current paper presents a method by which, when comparing three color values at each pixel to the corresponding ones from all its eight neighbors, it is attempted to embed message bits into the two least significant bits of a color component of an image that an acceptable color difference has happened in. Due to the mechanism proposed, this method makes the message difficult to be discovered. However, since message detection does not need to insert additional data to identify the colors containing message bits, changes in image is less and the imperceptibility is higher.

  13. A data parallel digitizer for a time-based simulation of CMOS Monolithic Active Pixel Sensors with FairRoot

    Science.gov (United States)

    Sitzmann, P.; Amar-Youcef, S.; Doering, D.; Deveaux, M.; Fröhlich, I.; Koziel, M.; Krebs, E.; Linnik, B.; Michel, J.; Milanovic, B.; Müntz, C.; Li, Q.; Stroth, J.; Tischler, T.

    2014-06-01

    CMOS Monolithic Active Pixel Sensors (MAPS) demonstrated excellent performances in the field of charged particle tracking. They feature an excellent single point resolution of few μm, a light material budget of 0.05% Xo in combination with a good radiation tolerance and time resolution. This makes the sensors a valuable technology for micro vertex detectors (MVD) of various experiments in heavy ion and particle physics like STAR and CBM. State of the art MAPS are equipped with a rolling shutter readout. Therefore, the data of one individual event is typically found in more than one data train generated by the sensor. This paper presents a concept to introduce this feature in both simulation and data analysis, taking profit of the sensor topology of the MVD. This topology allows to use for massive parallel data streaming and handling strategies within the FairRoot framework.

  14. A Tracker for the Mu3e Experiment based on High-Voltage Monolithic Active Pixel Sensors

    CERN Document Server

    Berger, Niklaus; Bachmann, Sebastian; Kiehn, Moritz; Perić, Ivan; Perrevoort, Ann-Kathrin; Philipp, Raphael; Schöning, André; Stumpf, Kevin; Wiedner, Dirk; Windelband, Bernd; Zimmermann, Marco

    2013-01-01

    The Mu3e experiment searches for the lepton flavour violating decay mu+ -> e+e-e+, aiming for a branching fraction sensitivity of 10^-16. This requires an excellent momentum resolution for low energy electrons, high rate capability and a large acceptance. In order to minimize multiple scattering, the amount of material has to be as small as possible. These challenges can be met with a tracker built from high-voltage monolithic active pixel sensors (HV-MAPS), which can be thinned to 50 um and which incorporate the complete read-out electronics on the sensor chip. To further minimise material, the sensors are supported by a mechanical structure built from 25 um thick Kapton foil and cooled with gaseous helium.

  15. Simulation studies and spectroscopic measurements of a position sensitive detector based on pixelated CdTe crystals

    CERN Document Server

    Karafasoulis, K; Seferlis, S; Kaissas, I; Lambropoulos, C; Loukas, D; Potiriadis, C

    2010-01-01

    Simulation studies and spectroscopic measurements are presented regarding the development of a pixel multilayer CdTe detector under development in the context of the COCAE project. The instrument will be used for the localization and identification of radioactive sources and radioactively contaminated spots. For the localization task the Compton effect is exploited. The detector response under different radiation fields as well as the overall efficiency of the detector has been evaluated. Spectroscopic measurements have been performed to evaluate the energy resolution of the detector. The efficiency of the event reconstruction has been studied in a wide range of initial photon energies by exploiting the detector's angular resolution measure distribution. Furthermore, the ability of the COCAE detector to localize radioactive sources has been investigated.

  16. A tracker for the Mu3e experiment based on high-voltage monolithic active pixel sensors

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Niklaus, E-mail: nberger@physi.uni-heidelberg.de [Physikalisches Institut, Heidelberg University, Heidelberg (Germany); Augustin, Heiko; Bachmann, Sebastian; Kiehn, Moritz [Physikalisches Institut, Heidelberg University, Heidelberg (Germany); Perić, Ivan [Zentralinstitut für technische Informatik, Heidelberg University, Mannheim (Germany); Perrevoort, Ann-Kathrin; Philipp, Raphael; Schöning, André; Stumpf, Kevin; Wiedner, Dirk; Windelband, Bernd; Zimmermann, Marco [Physikalisches Institut, Heidelberg University, Heidelberg (Germany)

    2013-12-21

    The Mu3e experiment searches for the lepton flavour violating decay μ{sup +}→e{sup +}e{sup −}e{sup +}, aiming for a branching fraction sensitivity of 10{sup −16}. This requires an excellent momentum resolution for low energy electrons, high rate capability and a large acceptance. In order to minimise multiple scattering, the amount of material has to be as small as possible. These challenges can be met with a tracker built from high-voltage monolithic active pixel sensors (HV-MAPS), which can be thinned to 50μm and which incorporate the complete read-out electronics on the sensor chip. To further minimise material, the sensors are supported by a mechanical structure built from 25μm thick Kapton foil and cooled with gaseous helium.

  17. A Framework Based on 2-D Taylor Expansion for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method

    Science.gov (United States)

    Zhang, Z.; Werner, F.; Cho, H. -M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

    2016-01-01

    The bi-spectral method retrieves cloud optical thickness and cloud droplet effective radius simultaneously from a pair of cloud reflectance observations, one in a visible or near-infrared (VISNIR) band and the other in a shortwave infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved and re. In the literature, the retrievals of and re are often assumed to be independent and considered separately when investigating the impact of sub-pixel cloud reflectance variations on the bi-spectral method. As a result, the impact on is contributed only by the sub-pixel variation of VISNIR band reflectance and the impact on re only by the sub-pixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VISNIR and SWIR cloud reflectances and their covariance on the and re retrievals. This framework takes into account the fact that the retrievals are determined by both VISNIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VISNIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from Moderate Resolution Imaging Spectroradiometer. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used

  18. Comparison of two position sensitive gamma-ray detectors based on continuous YAP and pixellated NaI(TI) for nuclear medical imaging applications

    Science.gov (United States)

    Zhu, Jie; Ma, Hong-Guang; Ma, Wen-Yan; Zeng, Hui; Wang, Zhao-Min; Xu, Zi-Zhong

    2008-11-01

    Dedicated position sensitive gamma-ray detectors based on position sensitive photomultiplier tubes (PSPMTs) coupled to scintillation crystals, have been used for the construction of compact gamma-ray imaging systems, suitable for nuclear medical imaging applications such as small animal imaging and single organ imaging and scintimammography. In this work, the performance of two gamma-ray detectors: a continuous YAP scintillation crystal coupled to a Hamamastu R2486 PSPMT and a pixellated NaI(TI) scintillation array crystal coupled to the same PSPMT, is compared. The results show that the gamma-ray detector based on a pixellated NaI(TI) scintillation array crystal is a promising candidate for nuclear medical imaging applications, since their performance in terms of position linearity, spatial resolution and effective field of view (FOV) is superior than that of the gamma-ray detector based on a continuous YAP scintillation crystal. However, a better photodetector (Hamamatau H8500 Flat Panel PMT, for example) coupled to the continuous crystal is also likely a good selection for nuclear medicine imaging applications. Supported by National Nature Science Foundation of China (10275063)

  19. Comparison of two position sensitive gamma-ray detectors based on continuous YAP and pixellated NaI(TI) for nuclear medical imaging applications

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Dedicated position sensitive gamma-ray detectors based on position sensitive photomultiplier tubes (PSPMTs) coupled to scintillation crystals, have been used for the construction of compact gamma-ray imaging systems, suitable for nuclear medical imaging applications such as small animal imaging and single organ imaging and scintimammography. In this work, the performance of two gamma-ray detectors: a continuous YAP scintillation crystal coupled to a Hamamastu R2486 PSPMT and a pixellated NaI(TI) scintillation array crystal coupled to the same PSPMT, is compared. The results show that the gamma-ray detector based on a pixellated NaI(TI) scintillation array crystal is a promising candidate for nuclear medical imaging applications,since their performance in terms of position linearity, spatial resolution and effective field of view (FOV) is superior than that of the gamma-ray detector based on a continuous YAP scintillation crystal. However, a better photodetector (Hamamatau H8500 Flat Panel PMT, for example) coupled to the continuous crystal is also likely a good selection for nuclear medicine imaging applications.

  20. 基于相邻像素结构的信息隐藏算法%An Extended Structured Steganography Based on Adjacency Pixel

    Institute of Scientific and Technical Information of China (English)

    唐明伟; 宋文

    2012-01-01

    An extened structured steganography based on adjacency pixel (ESSA) was proposed by analyzing the SPA algorithm and SIHA algorithm. ESSA can be used to analyze some properties of the image fixel pairs. Based on the properties, a monotonous sequence of restoration was found. The sequence can keep the statistic properties of the pair unchanged. The experiment results show that the method can resist the attack of SPA and its performance is better than that of others in the efficiency and hiding capacity of information hiding.%通过对SPA方法和SIHA算法的分析,提出了一种扩展结构化的LSB信息隐藏算法(an extened structured steganography based on adjacency pixel,ESSA).通过分析图像相邻像素结构体,找到相似的相邻像素结构体,根据这些相邻像素结构体的统计性质变化来隐藏信息.实验证明:该算法不仅能够有效的抵抗SPA统计分析方法,而且实现简单、计算量小,隐藏优于其他算法.

  1. Myocardial blood flow rate and capillary permeability for 99mTc-DTPA in patients with angiographically normal coronary arteries. Evaluation of the single-injection, residue detection method with intracoronary indicator bolus injection and the use of a mobile gamma camera

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Kelbaek, H; Efsen, F

    1994-01-01

    The aims of the present study were to quantitate myocardial perfusion and capillary permeability in the human heart by means of the single-injection, residue detection method using a mobile gamma camera. With this method, the intravascular mean transit time and the capillary extraction fraction (E...

  2. Characterization of Pixel Sensors

    CERN Document Server

    Oliveira, Felipe Ferraz

    2017-01-01

    It was commissioned at CERN ATLAS pixel group a fluorescence setup for characterization of pixel sensors. The idea is to measure the energies of different targets to calibrate your sensor. It was measured four matrices (80, 95, 98 and 106) of the Investigator1 sensor with different deep PW using copper, iron and titanium as target materials. The matrix 80 has a higher gain (0.065 ± 0.002) and matrix 106 has a better energy resolution (0.05 ± 0.04). The noise of the setup is around 3.6 mV .

  3. Extraction and Analysis of Mega Cities’ Impervious Surface on Pixel-based and Object-oriented Support Vector Machine Classification Technology: A case of Bombay

    Science.gov (United States)

    Yu, S. S.; Sun, Z. C.; Sun, L.; Wu, M. F.

    2017-02-01

    The object of this paper is to study the impervious surface extraction method using remote sensing imagery and monitor the spatiotemporal changing patterns of mega cities. Megacity Bombay was selected as the interesting area. Firstly, the pixel-based and object-oriented support vector machine (SVM) classification methods were used to acquire the land use/land cover (LULC) products of Bombay in 2010. Consequently, the overall accuracy (OA) and overall Kappa (OK) of the pixel-based method were 94.97% and 0.96 with a running time of 78 minutes, the OA and OK of the object-oriented method were 93.72% and 0.94 with a running time of only 17s. Additionally, OA and OK of the object-oriented method after a post-classification were improved up to 95.8% and 0.94. Then, the dynamic impervious surfaces of Bombay in the period 1973-2015 were extracted and the urbanization pattern of Bombay was analysed. Results told that both the two SVM classification methods could accomplish the impervious surface extraction, but the object-oriented method should be a better choice. Urbanization of Bombay experienced a fast extending during the past 42 years, implying a dramatically urban sprawl of mega cities in the developing countries along the One Belt and One Road (OBOR).

  4. Automatic detection and segmentation of vascular structures in dermoscopy images using a novel vesselness measure based on pixel redness and tubularness

    Science.gov (United States)

    Kharazmi, Pegah; Lui, Harvey; Stoecker, William V.; Lee, Tim

    2015-03-01

    Vascular structures are one of the most important features in the diagnosis and assessment of skin disorders. The presence and clinical appearance of vascular structures in skin lesions is a discriminating factor among different skin diseases. In this paper, we address the problem of segmentation of vascular patterns in dermoscopy images. Our proposed method is composed of three parts. First, based on biological properties of human skin, we decompose the skin to melanin and hemoglobin component using independent component analysis of skin color images. The relative quantities and pure color densities of each component were then estimated. Subsequently, we obtain three reference vectors of the mean RGB values for normal skin, pigmented skin and blood vessels from the hemoglobin component by averaging over 100000 pixels of each group outlined by an expert. Based on the Euclidean distance thresholding, we generate a mask image that extracts the red regions of the skin. Finally, Frangi measure was applied to the extracted red areas to segment the tubular structures. Finally, Otsu's thresholding was applied to segment the vascular structures and get a binary vessel mask image. The algorithm was implemented on a set of 50 dermoscopy images. In order to evaluate the performance of our method, we have artificially extended some of the existing vessels in our dermoscopy data set and evaluated the performance of the algorithm to segment the newly added vessel pixels. A sensitivity of 95% and specificity of 87% were achieved.

  5. A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter

    Directory of Open Access Journals (Sweden)

    Assim Boukhayma

    2016-03-01

    Full Text Available This paper presents the first low noise complementary metal oxide semiconductor (CMOS terahertz (THz imager based on source modulation and in-pixel high-Q filtering. The 31 × 31 focal plane array has been fully integrated in a 0 . 13 μ m standard CMOS process. The sensitivity has been improved significantly by modulating the active THz source that lights the scene and performing on-chip high-Q filtering. Each pixel encompass a broadband bow tie antenna coupled to an N-type metal-oxide-semiconductor (NMOS detector that shifts the THz radiation, a low noise adjustable gain amplifier and a high-Q filter centered at the modulation frequency. The filter is based on a passive switched-capacitor (SC N-path filter combined with a continuous-time broad-band Gm-C filter. A simplified analysis that helps in designing and tuning the passive SC N-path filter is provided. The characterization of the readout chain shows that a Q factor of 100 has been achieved for the filter with a good matching between the analytical calculation and the measurement results. An input-referred noise of 0 . 2 μ V RMS has been measured. Characterization of the chip with different THz wavelengths confirms the broadband feature of the antenna and shows that this THz imager reaches a total noise equivalent power of 0 . 6 nW at 270 GHz and 0 . 8 nW at 600 GHz.

  6. A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter.

    Science.gov (United States)

    Boukhayma, Assim; Dupret, Antoine; Rostaing, Jean-Pierre; Enz, Christian

    2016-03-03

    This paper presents the first low noise complementary metal oxide semiconductor (CMOS) deletedCMOS terahertz (THz) imager based on source modulation and in-pixel high-Q filtering. The 31 × 31 focal plane array has been fully integrated in a 0 . 13 μ m standard CMOS process. The sensitivity has been improved significantly by modulating the active THz source that lights the scene and performing on-chip high-Q filtering. Each pixel encompass a broadband bow tie antenna coupled to an N-type metal-oxide-semiconductor (NMOS) detector that shifts the THz radiation, a low noise adjustable gain amplifier and a high-Q filter centered at the modulation frequency. The filter is based on a passive switched-capacitor (SC) N-path filter combined with a continuous-time broad-band Gm-C filter. A simplified analysis that helps in designing and tuning the passive SC N-path filter is provided. The characterization of the readout chain shows that a Q factor of 100 has been achieved for the filter with a good matching between the analytical calculation and the measurement results. An input-referred noise of 0 . 2 μ V RMS has been measured. Characterization of the chip with different THz wavelengths confirms the broadband feature of the antenna and shows that this THz imager reaches a total noise equivalent power of 0 . 6 nW at 270 GHz and 0 . 8 nW at 600 GHz.

  7. 基于超像素的人工神经网络图像分类%Artificial Neural Network Image Classification Based on Super-pixel

    Institute of Scientific and Technical Information of China (English)

    饶倩; 文红; 喻文; 毛祺琦; 苏伟伟

    2013-01-01

    基于人工神经网络对图像标签分类,为简化后续数据处理,先用Normalized Cut将图像分割为超像素,提取特征向量,通过输入训练样本集,对网络进行训练,在最小均方误差意义下得到网络参数,最后在Matlab的仿真实验中基于不同隐藏层节点,使用BP神经网络模型对图像超像素进行分类。%This paper describes the classification of image labeling based on artificial neural network .For simplifying the data processing , obtaining the super-pixel as a result of image segmentation , we took the extracted feature vectors as input for network , obtained the parameters of network in the sense of minimum mean square error after training the network with training samples .At last, in the simulation experiments of Matlab , we classified the super-pixel of image based on BP neural network model for all hidden neurons .

  8. A comparison of change detection measurements using object-based and pixel-based classification methods on western juniper dominated woodlands in eastern Oregon

    Directory of Open Access Journals (Sweden)

    Ryan G. Howell

    2017-03-01

    Full Text Available Encroachment of pinyon (Pinus spp and juniper (Juniperus spp. woodlands in western North America is considered detrimental due to its effects on ecohydrology, plant community structure, and soil stability. Management plans at the federal, state, and private level often include juniper removal for improving habitat of sensitive species and maintaining sustainable ecosystem processes. Remote sensing has become a useful tool in determining changes in juniper woodland structure because of its uses in comparing archived historic imagery with newly available multispectral images to provide information on changes that are no longer detectable by field measurements. Change in western juniper (J. occidentalis cover was detected following juniper removal treatments between 1995 and 2011 using panchromatic 1-meter NAIP and 4-band 1-meter NAIP imagery, respectively. Image classification was conducted using remotely sensed images taken at the Roaring Springs Ranch in southeastern Oregon. Feature Analyst for ArcGIS (object-based extraction and a supervised classification with ENVI 5.2 (pixel-based extraction were used to delineate juniper canopy cover. Image classification accuracy was calculated using an Accuracy Assessment and Kappa Statistic. Both methods showed approximately a 76% decrease in western juniper cover, although differing in total canopy cover area, with object-based classification being more accurate. Classification results for the 2011 imagery were much more accurate (0.99 Kappa statistic because of its low juniper density and the presence of an infrared band. The development of methods for detecting change in juniper cover can lead to more accurate and efficient data acquisition and subsequently improved land management and monitoring practices. These data can subsequently be used to assess and quantify juniper invasion and succession, potential ecological impacts, and plant community resilience.

  9. Pixel detectors from fundamentals to applications

    CERN Document Server

    Rossi, Leonardo; Rohe, Tilman; Wermes, Norbert

    2006-01-01

    Pixel detectors are a particularly important class of particle and radiation detection devices. They have an extremely broad spectrum of applications, ranging from high-energy physics to the photo cameras of everyday life. This book is a general purpose introduction into the fundamental principles of pixel detector technology and semiconductor-based hybrid pixel devices. Although these devices were developed for high-energy ionizing particles and radiation beyond visible light, they are finding new applications in many other areas. This book will therefore benefit all scientists and engineers working in any laboratory involved in developing or using particle detection.

  10. Pixel detector insertion

    CERN Multimedia

    CMS

    2015-01-01

    Insertion of the Pixel Tracker, the 66-million-channel device used to pinpoint the vertex of each colliding proton pair, located at the heart of the detector. The geometry of CMS is a cylinder lying on its side (22 meters long and 15 meters high in dia

  11. Pixel detector readout chip

    CERN Multimedia

    1991-01-01

    Close-up of a pixel detector readout chip. The photograph shows an aera of 1 mm x 2 mm containing 12 separate readout channels. The entire chip contains 1000 readout channels (around 80 000 transistors) covering a sensitive area of 8 mm x 5 mm. The chip has been mounted on a silicon detector to detect high energy particles.

  12. ALICE Silicon Pixel Detector

    CERN Multimedia

    Manzari, V

    2013-01-01

    The Silicon Pixel Detector (SPD) forms the innermost two layers of the 6-layer barrel Inner Tracking System (ITS). The SPD plays a key role in the determination of the position of the primary collision and in the reconstruction of the secondary vertices from particle decays.

  13. Monitoring of Oil Exploitation Infrastructure by Combining Unsupervised Pixel-Based Classification of Polarimetric SAR and Object-Based Image Analysis

    Directory of Open Access Journals (Sweden)

    Simon Plank

    2014-12-01

    Full Text Available In developing countries, there is a high correlation between the dependence of oil exports and violent conflicts. Furthermore, even in countries which experienced a peaceful development of their oil industry, land use and environmental issues occur. Therefore, independent monitoring of oil field infrastructure may support problem solving. Earth observation data enables fast monitoring of large areas which allows comparing the real amount of land used by the oil exploitation and the companies’ contractual obligations. The target feature of this monitoring is the infrastructure of the oil exploitation, oil well pads—rectangular features of bare land covering an area of approximately 50–60 m × 100 m. This article presents an automated feature extraction procedure based on the combination of a pixel-based unsupervised classification of polarimetric synthetic aperture radar data (PolSAR and an object-based post-classification. The method is developed and tested using dual-polarimetric TerraSAR-X imagery acquired over the Doba basin in south Chad. The advantages of PolSAR are independence of the cloud coverage (vs. optical imagery and the possibility of detailed land use classification (vs. single-pol SAR. The PolSAR classification uses the polarimetric Wishart probability density function based on the anisotropy/entropy/alpha decomposition. The object-based post-classification refinement, based on properties of the feature targets such as shape and area, increases the user’s accuracy of the methodology by an order of a magnitude. The final achieved user’s and producer’s accuracy is 59%–71% in each case (area based accuracy assessment. Considering only the numbers of correctly/falsely detected oil well pads, the user’s and producer’s accuracies increase to even 74%–89%. In an iterative training procedure the best suited polarimetric speckle filter and processing parameters of the developed feature extraction procedure are

  14. Upgrades of the ATLAS Pixel Detector

    CERN Document Server

    Hügging, F; The ATLAS collaboration

    2013-01-01

    The upgrade for the ATLAS detector will undergo different phases towards HL-LHC. The first upgrade for the Pixel Detector (Phase 1) consists in the construction of a new pixel layer, which will be installed during the 1st long shutdown of the LHC machine (LS1) in 2013/14. The new detector, called Insertable B-Layer (IBL), will be inserted between the existing pixel detector and a new (smaller radius) beam-pipe at a radius of about 3.2 cm. The IBL requires the development of several new technologies to cope with the increase of radiation and pixel occupancy as well as to improve the physics performance of the existing pixel detector. The pixel size is reduced and the material budget is minimized by using new lightweight mechanical support materials and a CO2 based cooling system. For Phase 2 upgrade of LHC a complete new 4-layer pixel system is planned as part of a new all silicon Inner Detector. The increase in luminosity to about $5\\cdot 10^{34}$cm$^{-2}$s$^{-1}$ together with a total expected lifetime of ab...

  15. Design and characterization of a 256 x 64-pixel single-photon imager in CMOS for a MEMS-based laser scanning time-of-flight sensor.

    Science.gov (United States)

    Niclass, Cristiano; Ito, Kota; Soga, Mineki; Matsubara, Hiroyuki; Aoyagi, Isao; Kato, Satoru; Kagami, Manabu

    2012-05-21

    We introduce an optical time-of-flight image sensor taking advantage of a MEMS-based laser scanning device. Unlike previous approaches, our concept benefits from the high timing resolution and the digital signal flexibility of single-photon pixels in CMOS to allow for a nearly ideal cooperation between the image sensor and the scanning device. This technique enables a high signal-to-background light ratio to be obtained, while simultaneously relaxing the constraint on size of the MEMS mirror. These conditions are critical for devising practical and low-cost depth sensors intended to operate in uncontrolled environments, such as outdoors. A proof-of-concept prototype capable of operating in real-time was implemented. This paper focuses on the design and characterization of a 256 x 64-pixel image sensor, which also comprises an event-driven readout circuit, an array of 64 row-level high-throughput time-to-digital converters, and a 16 Gbit/s global readout circuit. Quantitative evaluation of the sensor under 2 klux of background light revealed a repeatability error of 13.5 cm throughout the distance range of 20 meters.

  16. Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

    Science.gov (United States)

    Kolstein, M.; Chmeissani, M.

    2016-01-01

    The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

  17. Design of a CZT Gamma-Camera for GRB and Fast Transient Follow-up: a Wide-Field-Monitor for the EDGE Mission

    CERN Document Server

    Natalucci, L; Quadrini, E; Ubertini, P; Piro, L; Herder, J W den; Barret, D; Amati, L; Budtz-Jorgensen, C; Caroli, E; Di Cosimo, S; Frutti, M; Labanti, C; Monzani, F; Poulsen, J M; Nicolini, L; Stevoli, A

    2008-01-01

    The success of the SWIFT/BAT and INTEGRAL missions has definitely opened a new window for follow-up and deep study of the transient gamma-ray sky. This now appears as the access key to important progresses in the area of cosmological research and deep understanding of the physics of compact objects. To detect in near real-time explosive events like Gamma-Ray bursts, thermonuclear flashes from Neutron Stars and other types of X-ray outbursts we have developed a concept for a wide-field gamma-ray coded mask instrument working in the range 8-200 keV, having a sensitivity of 0.4 ph cm-2 s-1 in 1s (15-150 keV) and arcmin location accuracy over a sky region as wide as 3sr. This scientific requirement can be achieved by means of two large area, high spatial resolution CZT detection planes made of arrays of relatively large (~1cm2) crystals, which are in turn read out as matrices of smaller pixels. To achieve such a wide Field-Of-View the two units can be placed at the sides of a S/C platform serving a payload with a...

  18. ATLAS ITk Pixel detector

    CERN Document Server

    Gemme, Claudia; The ATLAS collaboration

    2016-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenge to the ATLAS tracker. The current inner detector will be replaced with a whole silicon tracker which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation level are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the HL-LHC ATLA Pixel detector developments as well as the various layout options will be reviewed.

  19. Fast Sub-Pixel Motion Estimation Algorithm For H.264

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel fast sub-pixel search algorithm is proposed to accelerate sub-pixel search. Based on the features of predicted motion vector (PMV) and texture direction observed, the proposed method effectively filters out impossible points and thus decreases 11 searched points in average during the sub-pixel search stage. A threshold is also adopted to early terminate the sub-pixel search. Simulation results show that the proposed method can achieve up to 4.8 times faster than full sub-pixel motion search scheme (FSPS) with less than 0.025 dB PSNR losses and 2.2% bitlength increases.

  20. Simulation study of pixel detector charge digitization

    Science.gov (United States)

    Wang, Fuyue; Nachman, Benjamin; Sciveres, Maurice; Lawrence Berkeley National Laboratory Team

    2017-01-01

    Reconstruction of tracks from nearly overlapping particles, called Tracking in Dense Environments (TIDE), is an increasingly important component of many physics analyses at the Large Hadron Collider as signatures involving highly boosted jets are investigated. TIDE makes use of the charge distribution inside a pixel cluster to resolve tracks that share one of more of their pixel detector hits. In practice, the pixel charge is discretized using the Time-over-Threshold (ToT) technique. More charge information is better for discrimination, but more challenging for designing and operating the detector. A model of the silicon pixels has been developed in order to study the impact of the precision of the digitized charge distribution on distinguishing multi-particle clusters. The output of the GEANT4-based simulation is used to train neutral networks that predict the multiplicity and location of particles depositing energy inside one cluster of pixels. By studying the multi-particle cluster identification efficiency and position resolution, we quantify the trade-off between the number of ToT bits and low-level tracking inputs. As both ATLAS and CMS are designing upgraded detectors, this work provides guidance for the pixel module designs to meet TIDE needs. Work funded by the China Scholarship Council and the Office of High Energy Physics of the U.S. Department of Energy under contract DE-AC02-05CH11231.

  1. 基于亚像素的埋弧焊焊缝图像处理%SAW edge detection of image based on sub-pixel

    Institute of Scientific and Technical Information of China (English)

    张姝; 张文明; 王滨

    2011-01-01

    Submerged arc welding is one of the widespread welding technology.It has high efficiency,good weld quality.no arc radiation, etc.It is more and more important/To improve the submerged arc welding process automatic and intelligent, increasing demands for precision tracking technology.In order to improve the accuracy of submerged arc welding, a sub-pixel location based on B Spline transform was put forward for welding line and dibided edge.The algorithm is conducting a Marr-Hildreth edge detection and a sub-pixel location.Field tests,achieved standard error less than 255.The traditional edge detection was low in precision,but the problem is constraining by using the transform.%埋弧焊是普遍使用的熔焊方法之一,具有生产效率高、焊缝成形好、没有弧光辐射等诸多优点,应用前景广阔.为了提高埋弧焊焊接过程的自动化和智能化,对埋弧焊精密跟踪技术的要求不断提高,需对焊缝间隙和坡口边缘进行精密检测.在此提出了一种基于B样条变换的亚像素定位算法,该算法是在对图像进行一次Marr-Hildreth边缘检测后再进行亚像素二次提取.通过现场试验,实现了检测标准误差小于255E/μm,克服了传统边缘检测精度低的问题.

  2. Development of an Ultrahigh Resolution Block Detector Based on 0.4 mm Pixel Ce:GAGG Scintillators and a Silicon Photomultiplier Array

    Science.gov (United States)

    Yamamoto, Seiichi; Yeom, Jung Yeol; Kamada, Kei; Endo, Takanori; Levin, Craig S.

    2013-12-01

    Ce doped Gd3Al2Ga3O12 (Ce:GAGG) is a newly developed single-crystal scintillator which has a large light output and longer emission light wavelength. The longer wavelength of the scintillation photons will produce a larger signal when coupled to typical silicon photomultiplier (Si-PM) as the quantum efficiency of semiconductor based photodetector is generally higher for light with longer wavelength. A block detector with higher spatial resolution may thus be realized by combining Ce:GAGG with Si-PM arrays. To achieve the highest possible spatial resolution for PET and SPECT detectors, we developed an ultrahigh resolution block detector using 0.4 mm × 0.4 mm × 5 mm Ce:GAGG pixels assembled to form a 24 × 24 matrix that is coupled to an Si-PM array and evaluated the performance. All Ce:GAGG pixels were separated in the 2-dimensional position histograms for Cs-137 (662 keV) gamma photons with an average peak-to-valley (P/V) ratio of 2.4. The energy resolution was 21.6% FWHM for Cs-137 (662 keV) and 23.8% for Co-57 (122 keV) gamma photons. Since Ce:GAGG does not contain naturally occurring radioisotope (Lu), beta-gamma true coincidences can be avoided and randoms are reduced when used for PET detectors. Furthermore, this property, together with its high light output and good intrinsic energy resolution, make the scintillator suited for SPECT detectors. An ultrahigh resolution PET/SPECT hybrid system might be an interesting application using Ce:GAGG/Si-PM block detectors.

  3. Use of a tantalum-178 generator and a multiwire gamma camera to study the effect of the Mueller maneuver on left ventricular performance: comparison to hemodynamics and single photon emission computed tomography perfusion patterns.

    Science.gov (United States)

    Gioia, G; Lin, B; Katz, R; DiMarino, A J; Ogilby, J D; Cassel, D; DePace, N L; Heo, J; Iskandrian, A S

    1995-11-01

    During the Mueller maneuver, there is a decrease in intrathoracic pressure and an increase in transmural left ventricular pressure. The changes in loading conditions cause transient left ventricular dysfunction. This study examined the effects of the Mueller maneuver on left ventricular performance using tantalum (Ta)-178 (half-life 9.3 min) and a multiwire gamma camera. First-pass radionuclide angiograms were obtained at baseline and during Mueller maneuver in 41 patients aged 58 +/- 10 years. In 34 patients, stress single photon emission computed tomography (SPECT) myocardial perfusion imaging with thallium-201 or sestamibi was also performed. Hemodynamic measurements during the Mueller maneuver (n = 10) showed a decrease in systemic pressure (139 +/- 25 mm Hg vs 123 +/- 24 mm Hg, p or = 5%) in 17 patients (group 2) (55% +/- 13% vs 40% +/- 16%, p = 0.001). The stress SPECT images showed no or only fixed defects in 11 (65%) patients in group 1 and 3 (18%) patients in group 2 (p = 0.02), and reversible defects in 6 (35%) patients in group 1 and 14 (82%) patients in group 2 (p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Pixelated neutron image plates

    Science.gov (United States)

    Schlapp, M.; Conrad, H.; von Seggern, H.

    2004-09-01

    Neutron image plates (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image plate can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image plates in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image plate for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image plate. However, this reduction in resolution can be restricted by a novel image plate concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image plate. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image plate material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image plates for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.

  5. The Kepler Pixel Response Function

    CERN Document Server

    Bryson, Stephen T; Jenkins, Jon M; Chandrasekaran, Hema; Klaus, Todd; Caldwell, Douglas A; Gilliland, Ronald L; Haas, Michael R; Dotson, Jessie L; Koch, David G; Borucki, William J

    2010-01-01

    Kepler seeks to detect sequences of transits of Earth-size exoplanets orbiting Solar-like stars. Such transit signals are on the order of 100 ppm. The high photometric precision demanded by Kepler requires detailed knowledge of how the Kepler pixels respond to starlight during a nominal observation. This information is provided by the Kepler pixel response function (PRF), defined as the composite of Kepler's optical point spread function, integrated spacecraft pointing jitter during a nominal cadence and other systematic effects. To provide sub-pixel resolution, the PRF is represented as a piecewise-continuous polynomial on a sub-pixel mesh. This continuous representation allows the prediction of a star's flux value on any pixel given the star's pixel position. The advantages and difficulties of this polynomial representation are discussed, including characterization of spatial variation in the PRF and the smoothing of discontinuities between sub-pixel polynomial patches. On-orbit super-resolution measurement...

  6. ATLAS-IBL Pixel Upgrade

    CERN Document Server

    LaRosa, A; The ATLAS collaboration

    2010-01-01

    The upgrade for the ATLAS detector will undergo different phase towards Super-LHC. The first upgrade for the Pixel Detector will consist in the construction of a new pixel layer which will be installed during the first shutdown of the LHC machine (SLHC Phase I). The new detector, called Insertable B-Layer (IBL), will be inserted between the existing pixel detector and a new (smaller radius) beam-pipe at a radius of 3.2 cm. The IBL will require the development of several new technologies to cope with increase of radiation or pixel occupancy and also to improve the physics performance which will be achieved by reduction of the pixel size and of the material budget. Three different promising sensor technologies (Planar-Si, 3D-Si and Diamond) are currently under investigation for the pixel detector. An overview of the project with particular emphasis on pixel module studies, irradiation and beam test plans will be presented.

  7. Comparison of ultra-high-resolution parallel-hole collimator materials based on the CdTe pixelated semiconductor SPECT system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Jin; Ryu, Hyun-Ju; Lee, Seung-Wan; Park, Su-Jin; Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr

    2013-06-11

    Recently, many studies have sought to improve the sensitivity and spatial resolution of pixelated semiconductor detectors. Spatial resolution can be improved by using a pinhole or pixelated parallel-hole collimator with equal hole and pixel sizes. We compared a pinhole to a pixelated parallel-hole collimator and found that the pixelated parallel-hole collimator had higher sensitivity. Additionally, collimator materials with high absorption efficiency are often used because of their high spatial resolution. The purpose of this study was to compare the quality of images generated using a pixelated semiconductor single photon emission computed tomography (SPECT) system simulated with pixelated parallel-hole collimators of lead, tungsten, gold, and depleted uranium. We performed a simulation study of the PID 350 (Ajat Oy Ltd., Finland) CdTe pixelated semiconductor detector, which consists of small pixels (0.35×0.35 mm{sup 2}), using a Geant4 Application for Tomographic Emission (GATE) simulation. Sensitivities and spatial resolutions were measured for the four collimator materials. To evaluate overall image performance, a hot-rod phantom was designed using GATE simulation. The results showed that with lead, sensitivity was 4.25%, 6.53%, and 10.28% higher than with tungsten, gold, and depleted uranium, respectively. Spatial resolution using depleted uranium was 3.19%, 4.19%, and 8.01% better than that of gold, tungsten, and lead, respectively. Sensitivity and spatial resolution showed little difference among the four types of collimator materials tested. It was difficult to visually distinguish between the reconstructed images of the hot-rod phantom for different collimator materials. The results are promising for notable cost reductions in collimator manufacturing while avoiding impractical and rare materials.

  8. Modelling semiconductor pixel detectors

    CERN Document Server

    Mathieson, K

    2001-01-01

    expected after 200 ps in most cases. The effect of reducing the charge carrier lifetime and examining the charge collection efficiency has been utilised to explore how these detectors would respond in a harsh radiation environment. It is predicted that over critical carrier lifetimes (10 ps to 0.1 ns) an improvement of 40 % over conventional detectors can be expected. This also has positive implications for fabricating detectors, in this geometry, from materials which might otherwise be considered substandard. An analysis of charge transport in CdZnTe pixel detectors has been performed. The analysis starts with simulation studies into the formation of contacts and their influence on the internal electric field of planar detectors. The models include a number of well known defect states and these are balanced to give an agreement with a typical experimental I-V curve. The charge transport study extends to the development of a method for studying the effect of charge sharing in highly pixellated detectors. The ...

  9. Comparison of region-of-interest-averaged and pixel-averaged analysis of DCE-MRI data based on simulations and pre-clinical experiments

    Science.gov (United States)

    He, Dianning; Zamora, Marta; Oto, Aytekin; Karczmar, Gregory S.; Fan, Xiaobing

    2017-09-01

    Differences between region-of-interest (ROI) and pixel-by-pixel analysis of dynamic contrast enhanced (DCE) MRI data were investigated in this study with computer simulations and pre-clinical experiments. ROIs were simulated with 10, 50, 100, 200, 400, and 800 different pixels. For each pixel, a contrast agent concentration as a function of time, C(t), was calculated using the Tofts DCE-MRI model with randomly generated physiological parameters (K trans and v e) and the Parker population arterial input function. The average C(t) for each ROI was calculated and then K trans and v e for the ROI was extracted. The simulations were run 100 times for each ROI with new K trans and v e generated. In addition, white Gaussian noise was added to C(t) with 3, 6, and 12 dB signal-to-noise ratios to each C(t). For pre-clinical experiments, Copenhagen rats (n  =  6) with implanted prostate tumors in the hind limb were used in this study. The DCE-MRI data were acquired with a temporal resolution of ~5 s in a 4.7 T animal scanner, before, during, and after a bolus injection (over the entire ROI, and (ii) by averaging C(t) over the entire ROI, and then fitting averaged C(t) to extract K trans and v e. The simulation results showed that in heterogeneous ROIs, the pixel-by-pixel averaged K trans was ~25% to ~50% larger (p  <  0.01) than the ROI-averaged K trans. At higher noise levels, the pixel-averaged K trans was greater than the ‘true’ K trans, but the ROI-averaged K trans was lower than the ‘true’ K trans. The ROI-averaged K trans was closer to the true K trans than pixel-averaged K trans for high noise levels. In pre-clinical experiments, the pixel-by-pixel averaged K trans was ~15% larger than the ROI-averaged K trans. Overall, with the Tofts model, the extracted physiological parameters from the pixel-by-pixel averages were larger than the ROI averages. These differences were dependent on the heterogeneity of the ROI.

  10. A Framework for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method.

    Science.gov (United States)

    Zhang, Z; Werner, F.; Cho, H. -M.; Wind, Galina; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

    2017-01-01

    The so-called bi-spectral method retrieves cloud optical thickness (t) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved t and re. In this study, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the t and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the t and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval.

  11. A Framework for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method.

    Science.gov (United States)

    Zhang, Z; Werner, F.; Cho, H. -M.; Wind, Galina; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

    2017-01-01

    The so-called bi-spectral method retrieves cloud optical thickness (t) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved t and re. In this study, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the t and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the t and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval.

  12. Pixels simultaneous detection probabilities and spatial resolution determination of pixelized detectors by means of correlation measurements

    CERN Document Server

    Grabskii, V

    2007-01-01

    A novel method to estimate the pixels simultaneous detection probability and the spatial resolution of pixelized detectors is proposed, which is based on the determination of the statistical correlations between detector neighbor pixels. The correlations are determined by means of noise variance measurement for a isolated pixels and the difference between neighbor pixels. The method is validated using images from the two different GE Senographe 2000D mammographic units. The pixelized detector has been irradiated using x-rays along its entire surface. It is shown that the pixel simultaneous detection probabilities can be estimated within accuracy 0.001 - 0.003, where the systematic error is estimated to be smaller than 0.005. The presampled two-dimensional point-spread function (PSF0) is determined using a single Gaussian and a sum of two Gaussian approximations. The obtained results for the presampled PSF0 show that the single Gaussian approximation is not appropriate, and the sum of two Gaussian approximatio...

  13. From Hybrid to CMOS Pixels ... a possibility for LHC's pixel future?

    CERN Document Server

    Wermes, Norbert

    2015-01-01

    Hybrid pixel detectors have been invented for the LHC to make tracking and vertexing possible at all in LHC's radiation intense environment. The LHC pixel detectors have meanwhile very successfully fulfilled their promises and R\\&D for the planned HL-LHC upgrade is in full swing, targeting even higher ionising doses and non-ionising fluences. In terms of rate and radiation tolerance hybrid pixels are unrivaled. But they have disadvantages as well, most notably material thickness, production complexity, and cost. Meanwhile also active pixel sensors (DEPFET, MAPS) have become real pixel detectors but they would by far not stand the rates and radiation faced from HL-LHC. New MAPS developments, so-called DMAPS (depleted MAPS) which are full CMOS-pixel structures with charge collection in a depleted region have come in the R\\&D focus for pixels at high rate/radiation levels. This goal can perhaps be realised exploiting HV technologies, high ohmic substrates and/or SOI based technologies. The paper covers t...

  14. The ALICE pixel detector upgrade

    Science.gov (United States)

    Reidt, F.

    2016-12-01

    The ALICE experiment at the CERN LHC is designed to study the physics of strongly interacting matter, and in particular the properties of the Quark-Gluon Plasma, using proton-proton, proton-nucleus and nucleus-nucleus collisions. The ALICE collaboration is preparing a major upgrade of the experimental apparatus to be installed during the second long LHC shutdown in the years 2019-2020. A key element of the ALICE upgrade is the new, ultra-light, high-resolution Inner Tracking System. With respect to the current detector, the new Inner Tracking System will significantly enhance the pointing resolution, the tracking efficiency at low transverse momenta, and the read-out rate capabilities. This will be obtained by seven concentric detector layers based on a Monolithic Active Pixel Sensor with a pixel pitch of about 30×30 μm2. A key feature of the new Inner Tracking System, which is optimised for high tracking accuracy at low transverse momenta, is the very low mass of the three innermost layers, which feature a material budget of 0.3% X0 per layer. This contribution presents the design goals and layout of the upgraded ALICE Inner Tracking System, summarises the R&D activities focussing on the technical implementation of the main detector components, and the projected detector performance.

  15. Background and muon counting rates in underground muon measurements with a plastic scintillator counter based on a wavelength shifting fibre and a multi-pixel avalanche photodiode readout

    National Research Council Canada - National Science Library

    Volchenko, Vladimir I; Akhrameev, Evgeniy V; Bezrukov, Leonid B; Dzaparova, Irina M; Davitashvili, Irakliy Sh; Enqvist, Timo; Fynbo, Hans; Guliev, Zhamal Sh; Inzhechik, Lev V; Izmaylov, Alexander O; Joutsenvaara, Jari; Khabibullin, Marat M; Khotjantsev, Alexey N; Kudenko, Yuri G; Kuusiniemi, Pasi; Lubsandorzhiev, Bayarto K; Lubsandorzhiev, Nima B; Mineev, Oleg V; Olanterä, Lauri; Petkov, Valeriy B; Poleshuk, Roman V; Räihä, Tomi; Shaibonov, Bator A. M; Sarkamo, Juho; Shaykhiev, Alexey T; Trzaska, Wladyslaw; Volchenko, Galina V; Yanin, Alexey F; Yershov, Nikolay V

    2010-01-01

    ...×3.0 cm3 size scintillator counter with a wavelength shifting fibre and a multi-pixel Geiger mode avalanche photodiode readout in the Baksan underground laboratory at a depth of 200 metres of water equivalent...

  16. Extensive simulation studies on the reconstructed image resolution of a position sensitive detector based on pixelated CdTe crystals

    CERN Document Server

    Zachariadou, K; Kaissas, I; Seferlis, S; Lambropoulos, C; Loukas, D; Potiriadis, C

    2011-01-01

    We present results on the reconstructed image resolution of a position sensitive radiation instrument (COCAE) based on extensive simulation studies. The reconstructed image resolution has been investigated in a wide range of incident photon energies emitted by point-like sources located at different source-to-detector distances on and off the detector's symmetry axis. The ability of the detector to distinguish multiple radioactive sources observed simultaneously is investigating by simulating point-like sources of different energies located on and off the detector's symmetry axis and at different positions

  17. Frequency-domain fluorescence lifetime imaging system (pco.flim) based on a in-pixel dual tap control CMOS image sensor

    Science.gov (United States)

    Franke, Robert; Holst, Gerhard A.

    2015-03-01

    The luminescence lifetime as a beneficial analytical parameter is known for many years and is well described by a large variety of publications. Many instruments including 2D measuring systems with cameras have been developed and applied in the past years. However, since the current instrumentation to perform either time- or frequency-domain lifetime measurements is rather complex, new developments in CMOS image sensor technology have achieved to create new image sensors, which can efficiently be integrated into easier-to-handle luminescence lifetime measuring systems. The principle of these modulatable CMOS image sensors, while initially being designed for distance measurements, shows a clear analogy to frequency-domain FLIM measurements, which was proven by researchers [1, 2]. Based on this principle a new CMOS image sensor has been developed, integrated into a camera system and has been investigated within a research project. The image sensor has a resolution of 1024 × 1024 pixels with a 5.6 μm pitch and can be modulated up to 50 MHz. First measurements show an effective dynamic range of larger than 1:1024 (corresponding to 10 bit dynamic). The maximum frame rate is in the range of 90 frames/s in dual-tap mode, resulting in an effective lifetime image frame rate for realistic measurements of approximately 22 frames/s. The camera system pco.flim, featuring that image sensor, generates all required modulation signals from 5 kHz to 50 MHz (sinusoidal and rectangular). It performs advanced pixel correction to generate linear and high-quality images, while the basic lifetime image processing is done in the computer. The modulation frequency can be freely adjusted within the specified range. The characteristics of the camera systems are presented, and first results are discussed using different representations of the data like for example the phasor approach [3], which has been established to provide a more global view to pixelwise fluorescence lifetime data and

  18. Improving Estimates of Grassland Fractional Vegetation Cover Based on a Pixel Dichotomy Model: A Case Study in Inner Mongolia, China

    Directory of Open Access Journals (Sweden)

    Fei Li

    2014-05-01

    Full Text Available Linear spectral mixture analysis (SMA is commonly used to infer fractional vegetation cover (FVC, especially for pixel dichotomy models. However, several sources of uncertainty including normalized difference vegetation index (NDVI saturation and selection of endmembers inhibit the effectiveness of SMA for the estimation of FVC. In this study, Moderate-resolution Imaging Spectroradiometer (MODIS and Landsat 8/Operational Land Imager (OLI remote sensing data for the early growing season and in situ measurement of spectral reflectance are used to determine the value of endmembers including VIsoil and VIveg, with equally weighted RVI and NDVI measures used in combination to minimize the inherent biases in pure NDVI-based FVC. Their ability to improve estimates of grassland FVC is analyzed at different resolutions. These are shown to improve FVC estimates over NDVI-based SMA models using fixed values for the endmembers. Grassland FVC changes for Inner Mongolia, China from 2000 to 2013 are then monitored using the MODIS data. The results show that changes in most grassland areas are not significant, but in parts of Hulunbeier, south Tongliao, middle Xilin Gol and Erdos, grassland FVC has increased significantly.

  19. Seasonal Separation of African Savanna Components Using Worldview-2 Imagery: A Comparison of Pixel- and Object-Based Approaches and Selected Classification Algorithms

    Directory of Open Access Journals (Sweden)

    Żaneta Kaszta

    2016-09-01

    Full Text Available Separation of savanna land cover components is challenging due to the high heterogeneity of this landscape and spectral similarity of compositionally different vegetation types. In this study, we tested the usability of very high spatial and spectral resolution WorldView-2 (WV-2 imagery to classify land cover components of African savanna in wet and dry season. We compared the performance of Object-Based Image Analysis (OBIA and pixel-based approach with several algorithms: k-nearest neighbor (k-NN, maximum likelihood (ML, random forests (RF, classification and regression trees (CART and support vector machines (SVM. Results showed that classifications of WV-2 imagery produce high accuracy results (>77% regardless of the applied classification approach. However, OBIA had a significantly higher accuracy for almost every classifier with the highest overall accuracy score of 93%. Amongst tested classifiers, SVM and RF provided highest accuracies. Overall classifications of the wet season image provided better results with 93% for RF. However, considering woody leaf-off conditions, the dry season classification also performed well with overall accuracy of 83% (SVM and high producer accuracy for the tree cover (91%. Our findings demonstrate the potential of imagery like WorldView-2 with OBIA and advanced supervised machine-learning algorithms in seasonal fine-scale land cover classification of African savanna.

  20. The ALICE pixel detector

    CERN Document Server

    Mercado Perez, J

    2002-01-01

    The present document is a brief summary of the performed activities during the 2001 Summer Student Programme at CERN under the Scientific Summer at Foreign Laboratories Program organized by the Particles and Fields Division of the Mexican Physical Society (Sociedad Mexicana de Fisica). In this case, the activities were related with the ALICE Pixel Group of the EP-AIT Division, under the supervision of Jeroen van Hunen, research fellow in this group. First, I give an introduction and overview to the ALICE experiment; followed by a description of wafer probing. A brief summary of the test beam that we had from July 13th to July 25th is given as well. (3 refs).

  1. Pixelated gamma detector

    Energy Technology Data Exchange (ETDEWEB)

    Dolinsky, Sergei Ivanovich; Yanoff, Brian David; Guida, Renato; Ivan, Adrian

    2016-12-27

    A pixelated gamma detector includes a scintillator column assembly having scintillator crystals and optical transparent elements alternating along a longitudinal axis, a collimator assembly having longitudinal walls separated by collimator septum, the collimator septum spaced apart to form collimator channels, the scintillator column assembly positioned adjacent to the collimator assembly so that the respective ones of the scintillator crystal are positioned adjacent to respective ones of the collimator channels, the respective ones of the optical transparent element are positioned adjacent to respective ones of the collimator septum, and a first photosensor and a second photosensor, the first and the second photosensor each connected to an opposing end of the scintillator column assembly. A system and a method for inspecting and/or detecting defects in an interior of an object are also disclosed.

  2. An Evaluation of Pixel-Based Methods for the Detection of Floating Objects on the Sea Surface

    Directory of Open Access Journals (Sweden)

    Barnich Olivier

    2010-01-01

    Full Text Available Ship-based automatic detection of small floating objects on an agitated sea surface remains a hard problem. Our main concern is the detection of floating mines, which proved a real threat to shipping in confined waterways during the first Gulf War, but applications include salvaging, search-and-rescue operation, perimeter, or harbour defense. Detection in infrared (IR is challenging because a rough sea is seen as a dynamic background of moving objects with size order, shape, and temperature similar to those of the floating mine. In this paper we have applied a selection of background subtraction algorithms to the problem, and we show that the recent algorithms such as ViBe and behaviour subtraction, which take into account spatial and temporal correlations within the dynamic scene, significantly outperform the more conventional parametric techniques, with only little prior assumptions about the physical properties of the scene.

  3. Fast pixelated sensors for radiation detection and imaging based on quantum confined structures in III/V semiconductors

    Science.gov (United States)

    Tortora, M.; Biasiol, G.; Cautero, G.; Menk, R. H.; Plaisier, J. R.; Antonelli, M.

    2017-03-01

    In order to improve the characterisation of the delivered beams in many types of photon sources, innovative beam profilers based on III/V semiconductor materials (InGaAs/InAlAs) have been deeply investigated. Owing to a tunable and direct band gap these devices allow radiation detection in a wide spectral range. In order to increase the sensitivity of the device in radiation detection charge amplification on the sensor level is implemented. This is obtained by exploiting In0.75Ga0.25As/In0.75Al0.25As quantum wells (QW) hosting a two-dimensional electron gas (2DEG) through molecular beam epitaxy (MBE). Internal charge-amplification mechanism can be achieved for very low applied voltages, while the high carrier mobility allows the design of very fast photon detectors with sub-nanosecond response times. This technology has been preliminarily exploited to fabricate prototype beam profilers with a strip geometry (with 50-μm-wide strips). Tests were carried out both with conventional X-ray tubes and at the Elettra synchrotron facility. The results testify how these profilers are capable of reconstructing the shape of the beam, as well as estimating the position of the beam centroid with a precision of about 400 nm. Further measurements with different samples of decreasing thickness have shown how this precision could be further improved by an optimised microfabrication. For this reason a new design, based on a membrane-photodetector, is proposed. Results regarding the spatial resolution as function of the sensor thickness will be presented and discussed.

  4. A method for the dynamic range extension of a pixelated Silicon detector beam profilometer based on the incomplete reset mechanism

    Science.gov (United States)

    Caccia, M.; Santoro, R.; Antonello, M.

    2017-03-01

    The SUCIMA collaboration, within a project supported by the European Commission in the Fifth Framework Program, developed a sensor for non-disruptive real-time beam profilometry for hadron therapy centres. The sensor, named MIMOTERA, has been used at different European facilities, imaging beams by direct impact on the sensor and by the detection of secondary electrons emitted by thin targets. In 2015, the detector has been thinned to 50 μm, integrated in a high vacuum and cryogenic temperature compliant assembly and successfully commissioned as antiproton beam monitor for the AEbar gIS experiment at CERN. The detector contributed to the optimisation of the experiment functionality providing the shape and position of the beam on a spill-by-spill basis. However, it failed in measuring the fluctuations of the beam intensity because the deposited energy exceeded the full well capacity and saturated the output signal. In order to recover this information, a method was developed based on the persistence of the signal in a series of frames that follows the one corresponding to the beam impact, due to the incomplete sensor reset. A laboratory test that makes use of a laser with tuneable intensity was designed and the method was qualified. This paper reports the description of the procedure and the main outcomes.

  5. Serial pixel analog-to-digital converter (ADC)

    Science.gov (United States)

    Larson, Eric D.

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and "one-hot" counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  6. Planar Pixelations and Image Recognition

    CERN Document Server

    Rowekamp, Brandon

    2011-01-01

    Any subset of the plane can be approximated by a set of square pixels. This transition from a shape to its pixelation is rather brutal since it destroys geometric and topological information about the shape. Using a technique inspired by Morse Theory, we algorithmically produce a PL approximation of the original shape using only information from its pixelation. This approximation converges to the original shape in a very strong sense: as the size of the pixels goes to zero we can recover important geometric and topological invariants of the original shape such as Betti numbers, area, perimeter and curvature measures.

  7. Steganography on quantum pixel images using Shannon entropy

    Science.gov (United States)

    Laurel, Carlos Ortega; Dong, Shi-Hai; Cruz-Irisson, M.

    2016-07-01

    This paper presents a steganographical algorithm based on least significant bit (LSB) from the most significant bit information (MSBI) and the equivalence of a bit pixel image to a quantum pixel image, which permits to make the information communicate secretly onto quantum pixel images for its secure transmission through insecure channels. This algorithm offers higher security since it exploits the Shannon entropy for an image.

  8. Characterization of a mammographic system based on single photon counting pixel arrays coupled to GaAs x-ray detectors.

    Science.gov (United States)

    Amendolia, S R; Bisogni, M G; Delogu, P; Fantacci, M E; Paternoster, G; Rosso, V; Stefanini, A

    2009-04-01

    The authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power spectrum, and the detective quantum efficiency (DQE) have been measured following the guidelines of the IEC 62220-1-2 protocol. The transfer function analysis has shown the high spatial resolution capabilities of the GaAs detectors. The MTF calculated at the Nyquist frequency (2.94 cycles/mm) is indeed 60%. The DQE, measured with a standard mammographic beam setup (Mo/Mo, 28 kVp, with 4 mm Al added filter) and calculated at zero frequency, is 46%. Aiming to further improve the system's image quality, the authors investigate the DQE limiting factors and show that they are mainly related to system engineering. For example, the authors show that optimization of the image equalization procedure increases the DQE(0) up to 74%, which is better than the DQE(0) of most clinical mammographic systems. The authors show how the high detection efficiency of GaAs detectors and the noise discrimination associated with the SPC technology allow optimizing the image quality in mammography. In conclusion, the authors propose technological solutions to exploit to the utmost the potentiality of GaAs detectors coupled to SPC electronics.

  9. A SPAD-based 3D imager with in-pixel TDC for 145ps-accuracy ToF measurement

    Science.gov (United States)

    Vornicu, I.; Carmona-Galán, R.; Rodríguez-Vázquez, Á.

    2015-03-01

    The design and measurements of a CMOS 64 × 64 Single-Photon Avalanche-Diode (SPAD) array with in-pixel Time-to-Digital Converter (TDC) are presented. This paper thoroughly describes the imager at architectural and circuit level with particular emphasis on the characterization of the SPAD-detector ensemble. It is aimed to 2D imaging and 3D image reconstruction in low light environments. It has been fabricated in a standard 0.18μm CMOS process, i. e. without high voltage or low noise features. In these circumstances, we are facing a high number of dark counts and low photon detection efficiency. Several techniques have been applied to ensure proper functionality, namely: i) time-gated SPAD front-end with fast active-quenching/recharge circuit featuring tunable dead-time, ii) reverse start-stop scheme, iii) programmable time resolution of the TDC based on a novel pseudo-differential voltage controlled ring oscillator with fast start-up, iv) a global calibration scheme against temperature and process variation. Measurements results of individual SPAD-TDC ensemble jitter, array uniformity and time resolution programmability are also provided.

  10. High-flux ptychographic imaging using the new 55 µm-pixel detector ‘Lambda’ based on the Medipix3 readout chip

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, R. N., E-mail: rwilke@gwdg.de; Wallentin, J.; Osterhoff, M. [University of Göttingen, Institute for X-ray Physics, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Pennicard, D.; Zozulya, A.; Sprung, M. [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg (Germany); Salditt, T. [University of Göttingen, Institute for X-ray Physics, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2014-11-01

    The Large Area Medipix-Based Detector Array (Lambda) has been used in a ptychographic imaging experiment on solar-cell nanowires. By using a semi-transparent central stop, the high flux density provided by nano-focusing Kirkpatrick–Baez mirrors can be fully exploited for high-resolution phase reconstructions. Suitable detection systems that are capable of recording high photon count rates with single-photon detection are instrumental for coherent X-ray imaging. The new single-photon-counting pixel detector ‘Lambda’ has been tested in a ptychographic imaging experiment on solar-cell nanowires using Kirkpatrick–Baez-focused 13.8 keV X-rays. Taking advantage of the high count rate of the Lambda and dynamic range expansion by the semi-transparent central stop, a high-dynamic-range diffraction signal covering more than seven orders of magnitude has been recorded, which corresponds to a photon flux density of about 10{sup 5} photons nm{sup −2} s{sup −1} or a flux of ∼10{sup 10} photons s{sup −1} on the sample. By comparison with data taken without the semi-transparent central stop, an increase in resolution by a factor of 3–4 is determined: from about 125 nm to about 38 nm for the nanowire and from about 83 nm to about 21 nm for the illuminating wavefield.

  11. The pin pixel detector--neutron imaging

    CERN Document Server

    Bateman, J E; Derbyshire, G E; Duxbury, D M; Marsh, A S; Rhodes, N J; Schooneveld, E M; Simmons, J E; Stephenson, R

    2002-01-01

    The development and testing of a neutron gas pixel detector intended for application in neutron diffraction studies is reported. Using standard electrical connector pins as point anodes, the detector is based on a commercial 100 pin connector block. A prototype detector of aperture 25.4 mmx25.4 mm has been fabricated, giving a pixel size of 2.54 mm which matches well to the spatial resolution typically required in a neutron diffractometer. A 2-Dimensional resistive divide readout system has been adapted to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics. The timing properties of the device match well to the requirements of the ISIS-pulsed neutron source.

  12. Per-Pixel Lighting Data Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Inanici, Mehlika

    2005-08-01

    This report presents a framework for per-pixel analysis of the qualitative and quantitative aspects of luminous environments. Recognizing the need for better lighting analysis capabilities and appreciating the new measurement abilities developed within the LBNL Lighting Measurement and Simulation Toolbox, ''Per-pixel Lighting Data Analysis'' project demonstrates several techniques for analyzing luminance distribution patterns, luminance ratios, adaptation luminance and glare assessment. The techniques are the syntheses of the current practices in lighting design and the unique practices that can be done with per-pixel data availability. Demonstrated analysis techniques are applicable to both computer-generated and digitally captured images (physically-based renderings and High Dynamic Range photographs).

  13. Realization and study of spectral properties of the ISGRI gamma-ray camera; Mise en oeuvre et etude des proprietes spectrales de la gamma-camera ISGRI

    Energy Technology Data Exchange (ETDEWEB)

    Limousin, O

    2001-11-01

    This work evaluates spectroscopic and physical properties of CdTe detectors in view of assembling a large number on a new generation spectro-imager for space gamma-ray astronomy. Study, optimization, realization and calibration of modular detection units of the ISGRI camera are described. After a description of the experimental context of the INTEGRAL program and a review of the physical processes involved in gamma-ray photon detectors, we present an analysis of the properties of CdTe detectors attempting to be so exhaustive as possible. We propose the base point of a global model, which relates charge transport properties, spectral response and possible instabilities in the detectors. We propose a new formulation of the Hecht relation that describes charge loss as a function of the detector charge transport properties. We discuss at length the method of charge loss correction and its consequences on the associated integrated electronics definition. Finally, we illustrate our instrument capabilities using as an example the observation of titanium 44 lines in historical supernovae. (author)

  14. Diamond pixel modules

    CERN Document Server

    Gan, K K; Robichaud, A; Potenza, R; Kuleshov, S; Kagan, H; Kass, R; Wermes, N; Dulinski, W; Eremin, V; Smith, S; Sopko, B; Olivero, P; Gorisek, A; Chren, D; Kramberger, G; Schnetzer, S; Weilhammer, P; Martemyanov, A; Hugging, F; Pernegger, H; Lagomarsino, S; Manfredotti, C; Mishina, M; Trischuk, W; Dobos, D; Cindro, V; Belyaev, V; Duris, J; Claus, G; Wallny, R; Furgeri, A; Tuve, C; Goldstein, J; Sciortino, S; Sutera, C; Asner, D; Mikuz, M; Lo Giudice, A; Velthuis, J; Hits, D; Griesmayer, E; Oakham, G; Frais-Kolbl, H; Bellini, V; D'Alessandro, R; Cristinziani, M; Barbero, M; Schaffner, D; Costa, S; Goffe, M; La Rosa, A; Bruzzi, M; Schreiner, T; de Boer, W; Parrini, G; Roe, S; Randrianarivony, K; Dolenc, I; Moss, J; Brom, J M; Golubev, A; Mathes, M; Eusebi, R; Grigoriev, E; Tsung, J W; Mueller, S; Mandic, I; Stone, R; Menichelli, D

    2011-01-01

    With the commissioning of the LHC in 2010 and upgrades expected in 2015, ATLAS and CMS are planning to upgrade their innermost tracking layers with radiation hard technologies. Chemical Vapor Deposition diamond has been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. This material is now being considered as a sensor material for use very close to the interaction region where the most extreme radiation conditions exist Recently the RD42 collaboration constructed, irradiated and tested polycrystalline and single-crystal chemical vapor deposition diamond sensors to the highest fluences expected at the super-LHC. We present beam test results of chemical vapor deposition diamond up to fluences of 1.8 x 10(16) protons/cm(2) illustrating that both polycrystalline and single-crystal chemical vapor deposition diamonds follow a single damage curve. We also present beam test results of irradiated complete diamond pixel m...

  15. Noiseless, kilohertz-frame-rate, imaging detector based on micro-channel plates readout with the Medipix2 CMOS pixel chip

    CERN Document Server

    McPhate, J; Tremsin, A; Siegmund, O; Mikulec, Bettina; Clark, Allan G; CERN. Geneva

    2005-01-01

    A new hybrid imaging detector is described that is being developed for the next generation adaptive optics (AO) wavefront sensors. The detector consists of proximity focused microchannel plates (MCPs) read out by pixelated CMOS application specific integrated circuit (ASIC) chips developed at CERN ("Medipix2"). Each Medipix2 pixel has an amplifier, lower and upper charge discriminators, and a 14-bit chounter. The 256x256 array can be read out noiselessly (photon counting) in 286 us. The Medipix2 is buttable on 3 sides to produce 512x(n*256) pixel devices. The readout can be electronically shuttered down to a terporal window of a few microseconds with an accuracy of 10 ns. Good quantum efficiencies can be achieved from the x-ray (open faced with opaque photocathodes) to the optical (sealed tube with multialkali or GaAs photocathode).

  16. From Pixels to Planets

    Science.gov (United States)

    Brownston, Lee; Jenkins, Jon M.

    2015-01-01

    The Kepler Mission was launched in 2009 as NASAs first mission capable of finding Earth-size planets in the habitable zone of Sun-like stars. Its telescope consists of a 1.5-m primary mirror and a 0.95-m aperture. The 42 charge-coupled devices in its focal plane are read out every half hour, compressed, and then downlinked monthly. After four years, the second of four reaction wheels failed, ending the original mission. Back on earth, the Science Operations Center developed the Science Pipeline to analyze about 200,000 target stars in Keplers field of view, looking for evidence of periodic dimming suggesting that one or more planets had crossed the face of its host star. The Pipeline comprises several steps, from pixel-level calibration, through noise and artifact removal, to detection of transit-like signals and the construction of a suite of diagnostic tests to guard against false positives. The Kepler Science Pipeline consists of a pipeline infrastructure written in the Java programming language, which marshals data input to and output from MATLAB applications that are executed as external processes. The pipeline modules, which underwent continuous development and refinement even after data started arriving, employ several analytic techniques, many developed for the Kepler Project. Because of the large number of targets, the large amount of data per target and the complexity of the pipeline algorithms, the processing demands are daunting. Some pipeline modules require days to weeks to process all of their targets, even when run on NASA's 128-node Pleiades supercomputer. The software developers are still seeking ways to increase the throughput. To date, the Kepler project has discovered more than 4000 planetary candidates, of which more than 1000 have been independently confirmed or validated to be exoplanets. Funding for this mission is provided by NASAs Science Mission Directorate.

  17. An Introduction to ATLAS Pixel Detector DAQ and Calibration Software Based on a Year's Work at CERN for the Upgrade from 8 to 13 TeV

    CERN Document Server

    Dreyer, Nicholas David

    An overview is presented of the ATLAS pixel detector Data Acquisition (DAQ) system obtained by the author during a year-long opportunity to work on calibration software for the 2015-16 Layer‑2 upgrade. It is hoped the document will function more generally as an easy entry point for future work on ATLAS pixel detector calibration systems. To begin with, the overall place of ATLAS pixel DAQ within the CERN Large Hadron Collider (LHC), the purpose of the Layer-2 upgrade and the fundamentals of pixel calibration are outlined. This is followed by a brief look at the high level structure and key features of the calibration software. The paper concludes by discussing some difficulties encountered in the upgrade project and how these led to unforeseen alternative enhancements, such as development of calibration “simulation” software allowing the soundness of the ongoing upgrade work to be verified while not all of the actual readout hardware was available for the most comprehensive testing.

  18. Bump bonding of pixel systems

    Energy Technology Data Exchange (ETDEWEB)

    Lozano, M. E-mail: manuel.lozano@cnm.es; Cabruja, E.; Collado, A.; Santander, J.; Ullan, M

    2001-11-01

    A pixel detector consists of an array of radiation sensing elements which is connected to an electronic read-out unit. Many different ways of making this connection between these two different devices are currently being used or considered to be used in the next future. Bonding techniques such as flip chip technology can present real advantages because they allow very fine pitch and a high number of I/Os. This paper presents a review of the different flip chip technologies available and their suitability for manufacturing pixel detectors. The particular problems concerning testing of pixel detectors and thermal issues related to them are pointed out.

  19. Bump bonding of pixel systems

    CERN Document Server

    Lozano, M; Collado, A; Santander, J; Ullán, M

    2001-01-01

    A pixel detector consists of an array of radiation sensing elements which is connected to an electronic read-out unit. Many different ways of making this connection between these two different devices are currently being used or considered to be used in the next future. Bonding techniques such as flip chip technology can present real advantages because they allow very fine pitch and a high number of I/Os. This paper presents a review of the different flip chip technologies available and their suitability for manufacturing pixel detectors. The particular problems concerning testing of pixel detectors and thermal issues related to them are pointed out.

  20. CMS Barrel Pixel Detector Overview

    CERN Document Server

    Kästli, H C; Erdmann, W; Gabathuler, K; Hörmann, C; Horisberger, Roland Paul; König, S; Kotlinski, D; Meier, B; Robmann, P; Rohe, T; Streuli, S

    2007-01-01

    The pixel detector is the innermost tracking device of the CMS experiment at the LHC. It is built from two independent sub devices, the pixel barrel and the end disks. The barrel consists of three concentric layers around the beam pipe with mean radii of 4.4, 7.3 and 10.2 cm. There are two end disks on each side of the interaction point at 34.5 cm and 46.5 cm. This article gives an overview of the pixel barrel detector, its mechanical support structure, electronics components, services and its expected performance.

  1. Efficient segmentation by sparse pixel classification

    DEFF Research Database (Denmark)

    Dam, Erik B; Loog, Marco

    2008-01-01

    Segmentation methods based on pixel classification are powerful but often slow. We introduce two general algorithms, based on sparse classification, for optimizing the computation while still obtaining accurate segmentations. The computational costs of the algorithms are derived......, and they are demonstrated on real 3-D magnetic resonance imaging and 2-D radiograph data. We show that each algorithm is optimal for specific tasks, and that both algorithms allow a speedup of one or more orders of magnitude on typical segmentation tasks....

  2. 基于局部像素特征分类的图像分割算法%Image segmentation based on local pixel features classification

    Institute of Scientific and Technical Information of China (English)

    王向阳; 孙炜玮; 杨红颖; 王钦琰; 刘阳成; 王爱龙

    2014-01-01

    图像分割是模式识别、计算机视觉等领域的重要研究内容,也是图像信息处理的难点和热点之一。以孪生支持向量机(TSVM )与极坐标复指数变换(PCET )理论为基础,提出了一种基于局部像素特征分类的图像分割算法。该算法首先对局部像素窗口进行PCET ,并将PCET系数幅值作为图像的像素级特征;然后利用指数交叉熵阈值技术确定训练样本,并进一步训练出TSVM 分类模型;最后利用已获得的 TSVM 分类模型对原图像像素进行分类处理,从而获得图像的最终分割结果。实验结果表明,该算法可以获得较好的图像分割结果。%Image segmentation is a classic inverse problem w hich consists of achieving a compact re‐gion‐based description of the image scene by decomposing it into meaningful or spatially coherent re‐gions sharing similar attributes .Image segmentation is of great importance in the field of image pro‐cessing .In this paper ,we present an effective image segmentation approach based on local pixel fea‐tures classification .Firstly ,the pixel‐level image feature is extracted via Polar Complex Exponential Transform (PCET) .Then ,the pixel‐level image feature is used as input of twin support vector ma‐chine (TSVM ) model (classifier) ,and the TSVM model (classifier) is trained by selecting the train‐ing samples with the exponential cross entropy thresholding .Finally ,the image is segmented with the trained TSVM model (classifier) .This image segmentation not only can fully take advantage of the local information of image ,but also the ability of TSVM classifier .Experimental evidence shows that the proposed method has very effective segmentation results in comparison with the state‐of‐the‐art segmentation methods proposed in the literature .

  3. Sub-pixel mapping in farming area remote sensing image based on improved spatial gravity model%基于改进空间引力模型的农作区遥感影像亚像元定位

    Institute of Scientific and Technical Information of China (English)

    吴尚蓉; 刘佳; 杨鹏

    2013-01-01

    Due to the limitation of the sensor spatial resolution and the complexity and diversity of objects, mixed image pixels generally exist in remote sensing images. Pixel unmixing can only get the composition ratio of each endmember in the pixel, rather than the spatial distribution of each endmember. Sub-pixel mapping was proposed to solve above-mentioned problem. Spatial gravity model is an iterative solution of sub-pixel mapping which is based on the sub-pixel scale, the spatial correlation is expressed by gravitational relationship between sub-pixels and neighboring mixed pixels. This model does not require complicated parameters and its calculation is relatively simple, so it has the advantages of iterative solution and has the potential to improve mapping accuracy and speed. From the discussion above, this paper proposes a sub-pixel mapping method based on improved spatial gravity model for farming area remote sensing image. Firstly, this paper analyses the initialization algorithm and optimization algorithm of original spatial gravity model. The original initialization algorithm uses random assignment, which affects the calculation accuracy of neighboring mixed pixel gravity values, decreases the mapping accuracy, increases the number of iterations of the whole model, and decreases the overall speed of the model; Based on original initialization algorithm, the original optimization algorithm also affect the model accuracy and speed to a certain extent. Secondly, this paper improves the initialization algorithm and optimization algorithm of spatial gravity model. Improved initialization algorithm enables the model to combine the advantages of direct solution and iterative solution, after initialization data have more spatial correlation, the initialization accuracy and speed are improved compared with random assignment; Improved optimization algorithm optimizes data on the basis of initialization, greatly reduces the number of iterations and improves the speed

  4. Readout Architecture for Hybrid Pixel Readout Chips

    CERN Document Server

    AUTHOR|(SzGeCERN)694170; Westerlund, Tomi; Wyllie, Ken

    The original contribution of this thesis to knowledge are novel digital readout architectures for hybrid pixel readout chips. The thesis presents asynchronous bus-based architecture, a data-node based column architecture and a network-based pixel matrix architecture for data transportation. It is shown that the data-node architecture achieves readout efficiency 99 % with half the output rate as a bus-based system. The network-based solution avoids ``broken'' columns due to some manufacturing errors, and it distributes internal data traffic more evenly across the pixel matrix than column-based architectures. An improvement of $>$ 10 % to the efficiency is achieved with uniform and non-uniform hit occupancies. Architectural design has been done using transaction level modeling ($TLM$) and sequential high-level design techniques for reducing the design and simulation time. It has been possible to simulate tens of column and full chip architectures using the high-level techniques. A decrease of $>$ 10 in run-time...

  5. Readout electronics for low dark count pixel detectors based on Geiger mode avalanche photodiodes fabricated in conventional CMOS technologies for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Vilella, E., E-mail: evilella@el.ub.es [Department of Electronics, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Arbat, A. [Department of Electronics, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Comerma, A.; Trenado, J. [Department of Structure and Constituents of Matter, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Alonso, O. [Department of Electronics, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Gascon, D. [Department of Structure and Constituents of Matter, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Vila, A. [Department of Electronics, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Garrido, L. [Department of Structure and Constituents of Matter, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain); Dieguez, A. [Department of Electronics, University of Barcelona (UB), Marti i Franques 1, 08028 Barcelona (Spain)

    2011-09-11

    High sensitivity and excellent timing accuracy of the Geiger mode avalanche photodiodes make them ideal sensors as pixel detectors for particle tracking in high energy physics experiments to be performed in future linear colliders. Nevertheless, it is well known that these sensors suffer from dark counts and afterpulsing noise, which induce false hits (indistinguishable from event detection) as well as an increase in the necessary area of the readout system. In this work, we present a comparison between APDs fabricated in a high voltage 0.35 {mu}m and a high integration 0.13 {mu}m commercially available CMOS technologies that has been performed to determine which of them best fits the particle collider requirements. In addition, a readout circuit that allows low noise operation is introduced. Experimental characterization of the proposed pixel is also presented in this work.

  6. The test of intrinsic uniformity is one of the basic tests to check the status of the detectors of gamma cameras, and as such is contained in RD 1 841/1997 Quality Control in Nuclear Medicine; Protocolo NEMA para el calculo de la uniformidad intrinsica en gamma-camaras: aplicacion y comparacion con el software del fabricante

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Soto, X. L.; Gonzalez Ruiz, C.; Lopez-Boto, M. A.; Polo Cezon, R.

    2015-07-01

    Spanish Protocol Quality Control Instrumentation in Nuclear Medicine provides guidelines for conducting this test, similar to those established in the NEMA protocol NEMA Protocol for the calculation of the uniformity intrinsic in GAMMA cameras: application and comparison with the SQFTWARE of the manufacturer. it is advisable to conduct a study to ensure that the results for the test of intrinsic uniformity of the software provided by the equipment manufacturer are equivalent to those obtained by applying the protocol recommended by the SEFM before using this software for performing quality control. (Author)

  7. Multi-scale feature learning on pixels and super-pixels for seminal vesicles MRI segmentation

    Science.gov (United States)

    Gao, Qinquan; Asthana, Akshay; Tong, Tong; Rueckert, Daniel; Edwards, Philip "Eddie"

    2014-03-01

    We propose a learning-based approach to segment the seminal vesicles (SV) via random forest classifiers. The proposed discriminative approach relies on the decision forest using high-dimensional multi-scale context-aware spatial, textual and descriptor-based features at both pixel and super-pixel level. After affine transformation to a template space, the relevant high-dimensional multi-scale features are extracted and random forest classifiers are learned based on the masked region of the seminal vesicles from the most similar atlases. Using these classifiers, an intermediate probabilistic segmentation is obtained for the test images. Then, a graph-cut based refinement is applied to this intermediate probabilistic representation of each voxel to get the final segmentation. We apply this approach to segment the seminal vesicles from 30 MRI T2 training images of the prostate, which presents a particularly challenging segmentation task. The results show that the multi-scale approach and the augmentation of the pixel based features with the super-pixel based features enhances the discriminative power of the learnt classifier which leads to a better quality segmentation in some very difficult cases. The results are compared to the radiologist labeled ground truth using leave-one-out cross-validation. Overall, the Dice metric of 0:7249 and Hausdorff surface distance of 7:0803 mm are achieved for this difficult task.

  8. 基于四原色像素结构的节能LED显示系统%Energy Saving LED Display System Based on Four Original Color Pixel Structure

    Institute of Scientific and Technical Information of China (English)

    屈朝辉

    2012-01-01

    This paper explains the pixel structure of LED display system by the principle of CIE chromaticity. Adopt the mixed color theory of the LED display system, design the LED display system circuit based on four primary colors RGBW pixel structure, and proved the circuit in high energy efficiency, reduce light pollution, and other aspects of the advantage.%本文从CIE色度原理解释了LED显示系统的像素结构,利用LED显示系统混色理论,设计出基于四原色RGBW像素结构的LED显示系统电路,并论证了该电路在高效节能、减少光污染等方面的优势。

  9. ORIGAMIX, a CdTe-based spectro-imager development for nuclear applications

    CERN Document Server

    Dubos, S; Schanne, S; Limousin, O; Carrel, F; Schoepff, V; Blondel, C

    2015-01-01

    The Astrophysics Division of CEA Saclay has a long history in the development of CdTe based pixelated detection planes for X and gamma-ray astronomy, with time-resolved imaging and spectrometric capabilities. The last generation, named Caliste HD, is an all-in-one modular instrument that fulfills requirements for space applications. Its full-custom front-end electronics is designed to work over a large energy range from 2 keV to 1 MeV with excellent spectroscopic performances, in particular between 10 and 100 keV (0.56 keV FWHM and 0.67 keV FWHM at 13.9 and 59.5 keV). In the frame of the ORIGAMIX project, a consortium based on research laboratories and industrials has been settled in order to develop a new generation of gamma camera. The aim is to develop a system based on the Caliste architecture for post-accidental interventions or homeland security, but integrating new properties (advanced spectrometry, hybrid working mode) and suitable for industry. A first prototype was designed and tested to acquire fee...

  10. Efficient defect pixel cluster detection and correction for Bayer CFA image sequences

    Science.gov (United States)

    Tajbakhsh, Touraj

    2011-01-01

    Image sensor arrays may have defect pixels, either originating from manufacturing or being developed over the lifetime of the image sensor array. Continuous defect pixel detection and correction performing during camera runtime is desirable. On-the-fly detection and correction is challenging since edges and high-frequency image content might get identified as defect pixel regions and intact pixels become corrupted during defect pixel replacement. We propose a table-based detection and correction method which by and by fills the non-volatile table during normal camera operation. In this work we model defect pixels and pixel clusters to be stuck to fixed values or at least fixed to a narrow value range whereas the local neighborhood of these pixels indicate a normal behavior. The idea is to temporally observe the value ranges of small group of pixels (e.g. 4x4 pixel blocks) and to decide about their defective condition depending on their variability with respect to their neighbor pixels. Our method is computationally efficient, requires no frame buffer, requires modest memory, and therefore is appropriate to operate in line-buffer based image signal processing (ISP) systems. Our results indicate high reliability in terms of detection rates and robustness against high-frequency image content. As part of the defect pixel replacement system we also propose a simple and efficient defect pixel correction method based on the mean of medians operating on the Bayer CFA image domain.

  11. Fabrication and Test of Pixelated CZT Detectors with Different Pixel Pitches and Thicknesses

    CERN Document Server

    Li, Q; Dowkontt, P; Martín, J; Beilicke, M; Jung, I; Groza, M; Bürger, A; De Geronimo, G; Krawczynski, H

    2008-01-01

    The main methods grown Cadmium Zinc Telluride (CZT) crystals with high yield and excellent homogeneity are Modified Horizontal Bridgman (MHB) and High Pressure Bridgman (HPB) processes, respectively. In this contribution, the readout system based on two 32-channel NCI-ASICs for pixellated CZT detector arrays has been developed and tested. The CZT detectors supplied by Orbotech (MHB) and eV products (HPB) are tested by NCI-ASIC readout system. The CZT detectors have an array of 8x8 or 11x11 pixel anodes fabricated on the anode surface with the area up to 2 cm x2 cm and the thickness of CZT detectors ranges from 0.5 cm to 1 cm. Energy spectra resolution and electron mobility-lifetime products of 8x8 pixels CZT detector with different thicknesses have been investigated.

  12. 面向对象的航空高光谱图像混合分类方法%A Hybrid of Object-based and Pixel-based Classification Method with Airborne Hyperspectral Imagery

    Institute of Scientific and Technical Information of China (English)

    李雪轲; 王晋年; 张立福; 杨杭; 刘凯

    2014-01-01

    Hyperspectral imagery generally contains hundreds of contiguous narrow bands, which could provide detailed spectral information for target detection and image classification. Traditional hyperspectral classification fails to generate expected results since it simply considers spectral or textural properties at the pixel scale in the context of natural complexity. In this article, a hybrid classification method was proposed which takes full advan-tages of spectral and spatial features by fusing object-based segmentation results with traditional per-pixel classi-fication results. Based on this concept, two specific hybrid classification approaches were employed:(1) the mix-ture of multi-scale segmentation and SVM classification and (2) the mixture of multi-band watershed segmenta-tion and SVM classification. In the first proposed method, spectral variations were attenuated by converting them into homogenous image objects at multiple scales;while, the latter method aggregates spatial information and morphological profiles into the segmented objects to achieve the homogeneous classification. The two classi-fication algorithms were applied to airborne hyperspectral imagery and the results show that the overall accuracy based on traditional pixel-wise classification reaches about 82.49%, relatively lower compared with the hybrid object-based classification methods, which are 92.63%(Method 1) and 96.13%(Method 2) respectively. In addi-tion, Method 2 performs better than Method 1 since it produced a smoother boundary, partly because Method 2 needs less user-defined parameters, and the iterative“trial-and-error”of which may affect the classification re-sults. In conclusion, this study demonstrates that the hybrid of object-based classification is a significantly more robust approach than the traditional per-pixel classifier. The proposed method overcomes the spectral confusion, solves the problem of land fragmentation, and provides a solution to map complex environments

  13. Small-Scale Readout Systems Prototype for the STAR PIXEL Detector

    Energy Technology Data Exchange (ETDEWEB)

    Szelezniak, Michal A.; Besson, Auguste; Colledani, Claude; Dorokhov, Andrei; Dulinski, Wojciech; Greiner, Leo C.; Himmi, Abdelkader; Hu, Christine; Matis, Howard S.; Ritter, Hans Georg; Rose, Andrew; Shabetai, Alexandre; Stezelberger, Thorsten; Sun, Xiangming; Thomas, Jim H.; Valin, Isabelle; Vu, Chinh Q.; Wieman, Howard H.; Winter, Marc

    2008-10-01

    A prototype readout system for the STAR PIXEL detector in the Heavy Flavor Tracker (HFT) vertex detector upgrade is presented. The PIXEL detector is a Monolithic Active Pixel Sensor (MAPS) based silicon pixel vertex detector fabricated in a commercial CMOS process that integrates the detector and front-end electronics layers in one silicon die. Two generations ofMAPS prototypes designed specifically for the PIXEL are discussed. We have constructed a prototype telescope system consisting of three small MAPS sensors arranged in three parallel and coaxial planes with a readout system based on the readout architecture for PIXEL. This proposed readout architecture is simple and scales to the size required to readout the final detector. The real-time hit finding algorithm necessary for data rate reduction in the 400 million pixel detector is described, and aspects of the PIXEL system integration into the existing STAR framework are addressed. The complete system has been recently tested and shown to be fully functional.

  14. Comparing three spaceborne optical sensors via fine scale pixel ...

    African Journals Online (AJOL)

    User @

    Pixel-based Urban Land Cover Classification Products ... operational VHR spaceborne measurement systems such as those envisaged under ...... zone correlated vegetation stratification in the Kruger National Park, South Africa', Physics and.

  15. 积雪混合像元光谱特征观测及解混方法比较%Observations of Snow Mixed Pixel Spectral Characteristics Using a Ground-Based Spectral Radiometer and Comparing with Unmixing Algorithms

    Institute of Scientific and Technical Information of China (English)

    郝晓华; 王杰; 王建; 黄晓东; 李弘毅; 刘艳

    2012-01-01

    The unmixing algorithms of mixed snow pixels and the fractional snow cover products are an important research direc-tion for snow remote sensing. In the present study, we first designed the mixed snow pixels of different snow fraction/proportion in Northern Xinjiang, China as ground truth. Then, a SVC HR-1024 ground-based spectral radiometer was used for measuring the spectral property of this designed pixel for different snow fractions and different underlying surfaces. Finally, using the measured spectral data, the four mixed-pixel decomposition models were validated and evaluated for their performance in terms of accuracy and computational efficiency. The results showed that the reflectivity does not decline linearly with the reduction of snow ratio in the pixel, and that the unmixing accuracy inversely depends on the scales of the observation. Further, the comparison of the above mentioned unmixing algotihms showed that the linear regression method has the worst accuracy, especially when the snow proportion is less than 50%; the accuracy of sparse regression algorithm and non-negative matrix factorization were slightly higher than the full constrained linear mixed-pixel decomposition; however, full constrained linear mixed-pixel decomposition method had higher computational efficiency than the other two methods; the sparse regression algorithm has lowest computational efficiency. With unmixing remote sensing images, due to the large data volumes, we must consider the algorithms' computational efficiency. This study would promote quantitative researches on snow mixed pixel decomposition, and provide a theoretical basis for accurately extracting the snow coverage of interest area using remote sensing images.%积雪混合像元分解方法研究及积雪比例产品的发展是积雪遥感的重要研究方向.在我国北疆地区利用SVC HR-1024野外便携式光谱仪观测了已知积雪比例的混合像元光谱特征并进行系统分析,同时,采用四

  16. Noise in a CMOS digital pixel sensor

    Institute of Scientific and Technical Information of China (English)

    Zhang Chi; Yao Suying; Xu Jiangtao

    2011-01-01

    Based on the study of noise performance in CMOS digital pixel sensor (DPS),a mathematical model of noise is established with the pulse-width-modulation (PWM) principle.Compared with traditional CMOS image sensors,the integration time is different and A/D conversion is implemented in each PWM DPS pixel.Then,the quantitative calculating formula of system noise is derived.It is found that dark current shot noise is the dominant noise source in low light region while photodiode shot noise becomes significantly important in the bright region.In this model,photodiode shot noise does not vary with luminance,but dark current shot noise does.According to increasing photodiode capacitance and the comparator's reference voltage or optimizing the mismatch in the comparator,the total noise can be reduced.These results serve as a guideline for the design of PWM DPS.

  17. Content Progressive Coding of Limited Bits/pixel Images

    DEFF Research Database (Denmark)

    Jensen, Ole Riis; Forchhammer, Søren

    1999-01-01

    A new lossless context based method for content progressive coding of limited bits/pixel images is proposed. Progressive coding is achieved by separating the image into contelnt layers. Digital maps are compressed up to 3 times better than GIF.......A new lossless context based method for content progressive coding of limited bits/pixel images is proposed. Progressive coding is achieved by separating the image into contelnt layers. Digital maps are compressed up to 3 times better than GIF....

  18. A Fast quarter-pixel motion estimation algorithm for H.264/AVC

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A fast quarter-pixel motion estimation algorithm is proposed in this paper. The proposed algorithm based on mathematical models of the motion compensated prediction errors. Unlike conventional quarter-pixel accurate motion estimation algorithm,proposed algorithm can avoid fractional-pixel interpolation and subsequent fractional-pixel search after integer-precision motion estimation. Experiments show that the proposed algorithm greatly reduces the computational complexity of quarterpixel motion estimation, while keeping the nearly equal quality of the image.

  19. Saliency Detection via Combining Region-Level and Pixel-Level Predictions with CNNs

    OpenAIRE

    Tang, Youbao; Wu, Xiangqian

    2016-01-01

    This paper proposes a novel saliency detection method by combining region-level saliency estimation and pixel-level saliency prediction with CNNs (denoted as CRPSD). For pixel-level saliency prediction, a fully convolutional neural network (called pixel-level CNN) is constructed by modifying the VGGNet architecture to perform multi-scale feature learning, based on which an image-to-image prediction is conducted to accomplish the pixel-level saliency detection. For region-level saliency estima...

  20. Synthesis Classification of Remote Sensing Image Based on Improved Pixel-level and Object-level Methods%基于改进的像素级和对象级的遥感影像合成分类

    Institute of Scientific and Technical Information of China (English)

    李刚; 万幼川

    2012-01-01

    The pixel- and object-level classification methods are investigated separately, while the hybrid of them has not been explored. This paper tries exploration on the hybrid of pixel- and object-level classification, and proposes synthesis classification method for remote sensing image based on improved pixel- and object-level classification. Firstly, an improved RBF neural network classifier is proposed to obtain the pixel-level classification result, and a hierarchy classification model based on improved fuzzy support vector machines and decision tree is utilized to obtain the object-level classification result. Then a specific synthesis algorithm ofpixel- and object-level classification is proposed to obtain the synthesis classification result. The experiments show the synthesis classifi- cation method can improve the accuracy of classification result effectively and provide more accurate classification result than single pixel- or object-level method.%像素级和对象级的分类研究分别作为两个独立的方向开展,二者的结合与优势互补还没有引起关注。对像素级和对象级分类方法的结合进行探索,提出基于改进的像素级和对象级的遥感影像合成分类方法。首先,以一种改进的RBF神经网络分类器进行像素级分类、以一种基于改进模糊支持向量机和决策树的层次分类模型进行对象级分类,获得多层次分类结果。然后,提出具体的像素级分类与对象级分类的合成算法,对多层次分类结果进行合成。试验表明,合成分类方法能有效地提高分类结果的精度,提供比单一像素级方法或对象级方法更准确的分类结果。

  1. MediSPECT: Single photon emission computed tomography system for small field of view small animal imaging based on a CdTe hybrid pixel detector

    Science.gov (United States)

    Accorsi, R.; Autiero, M.; Celentano, L.; Chmeissani, M.; Cozzolino, R.; Curion, A. S.; Frallicciardi, P.; Laccetti, P.; Lanza, R. C.; Lauria, A.; Maiorino, M.; Marotta, M.; Mettivier, G.; Montesi, M. C.; Riccio, P.; Roberti, G.; Russo, P.

    2007-02-01

    We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies on small animals with a small field of view (FOV) and high spatial resolution. The CdTe pixel detector (a 256×256 matrix of 55 μm square pixels) operating in single photon counting for detection of gamma-rays with low and medium energy (e.g. 125I, 27-35 keV, 99mTc, 140 keV), is bump bonded to the Medipix2 readout chip. The FOV of the MediSPECT scanner with a coded aperture mask collimator ranges from 6.3 mm (system spatial resolution 110 μm at 27-35 keV) to 24.3 mm. With a 0.30 mm pinhole the FOV ranges from 2.4 to 29 mm (where the system spatial resolution is 1.0 mm at 27-35 keV and 2.0 mm at 140 keV). MediSPECT will be used for in vivo imaging of small organs or tissue structures in mouse, e.g., brain, thyroid, heart or tumor.

  2. WFC3 Pixel Area Maps

    Science.gov (United States)

    Kalirai, J. S.; Cox, C.; Dressel, L.; Fruchter, A.; Hack, W.; Kozhurina-Platais, V.; Mack, J.

    2010-04-01

    We present the pixel area maps (PAMs) for the WFC3/UVIS and WFC3/IR detectors, and discuss the normalization of these images. HST processed flt images suffer from geometric distortion and therefore have pixel areas that vary on the sky. The counts (electrons) measured for a source on these images depends on the position of the source on the detector, an effect that is implicitly corrected when these images are multidrizzled into drz files. The flt images can be multiplied by the PAMs to yield correct and uniform counts for a given source irrespective of its location on the image. To ensure consistency between the count rate measured for sources in drz images and near the center of flt images, we set the normalization of the PAMs to unity at a reference pixel near the center of the UVIS mosaic and IR detector, and set the SCALE in the IDCTAB equal to the square root of the area of this reference pixel. The implications of this choice for photometric measurements are discussed.

  3. VNR CMS Pixel detector replacement

    CERN Document Server

    2017-01-01

    Joel Butler, spokesperson of the CMS collaboration explains how a team from many different partner institutes installed a new detector in CMS. This detector is the silicon pixel detector and they’ve been working on it for about five years, to replace one of our existing detectors. This detectors measures particles closer to the beam than any of the other components of this huge detector behind me. It gives us the most precise picture of tracks as they come out of the collisions and expand and travel through the detector. This particular device has twice as many pixels, 120 million, as opposed to about 68 million in the old detector and it can take data faster and pump it out to the analysis more quickly. 00’53’’ Images of the descent, insertion and installation of first piece of the Pixel detector on Tue Feb 28. Images of the descent, insertion and installation of second piece of the Pixel and the two cylinders being joined.

  4. Diamond and silicon pixel detectors in high radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Tsung, Jieh-Wen

    2012-10-15

    Diamond pixel detector is a promising candidate for tracking of collider experiments because of the good radiation tolerance of diamond. The diamond pixel detector must withstand the radiation damage from 10{sup 16} particles per cm{sup 2}, which is the expected total fluence in High Luminosity Large Hadron Collider. The performance of diamond and silicon pixel detectors are evaluated in this research in terms of the signal-to-noise ratio (SNR). Single-crystal diamond pixel detectors with the most recent readout chip ATLAS FE-I4 are produced and characterized. Based on the results of the measurement, the SNR of diamond pixel detector is evaluated as a function of radiation fluence, and compared to that of planar-silicon ones. The deterioration of signal due to radiation damage is formulated using the mean free path of charge carriers in the sensor. The noise from the pixel readout circuit is simulated and calculated with leakage current and input capacitance to the amplifier as important parameters. The measured SNR shows good agreement with the calculated and simulated results, proving that the performance of diamond pixel detectors can exceed the silicon ones if the particle fluence is more than 10{sup 15} particles per cm{sup 2}.

  5. Pixels Intensity Evolution to Describe the Plastic Films Deformation

    Directory of Open Access Journals (Sweden)

    Juan C. Briñez-De León

    2013-11-01

    Full Text Available This work proposes an approach for mechanical behavior description in the plastic film deformation using techniques for the images analysis, which are based on the intensities evolution of fixed pixels applied to an images sequence acquired through polarizing optical assembly implemented around the platform of the plastic film deformation. The pixels intensities evolution graphs, and mechanical behavior graphic of the deformation has dynamic behaviors zones which could be associated together.

  6. Status of the ATLAS pixel detector

    CERN Document Server

    Saavedra Aldo, F

    2005-01-01

    The ATLAS pixel detector is currently being constructed and will be installed in 2006 to be ready for commissioning at the Large Hadron Collider. The complete pixel detector is composed of three concentric barrels and six disks that are populated by 1744 ATLAS Pixel modules. The main components of the pixel module are the readout electronics and the silicon sensor whose active region is instrumented with rectangular pixels. The module has been designed to be able to survive 10 years of operation within the ATLAS detector. A brief description of the pixel detector will be presented with results and problems encountered during the production stage.

  7. A method for multifocus image fusion in NSCT domain based on pixel clarity%一种基于像素清晰度的NSCT域多聚焦图像融合方法

    Institute of Scientific and Technical Information of China (English)

    时海亮; 黄海洋; 李刚

    2012-01-01

    Considering the problem that NSCT-based multiresolution fusion methods may change the reliable information during the process of decomposition and reconstruction, a multifocus image fusion method based on a new pixel clarity measure and NSCT in spatial domain was proposed. According to the characteristics of the human visual system ( HVS) of frequency and direction selectivity, and the distribution difference between the image' s salient features and the noise in NSCT domain, the conception of local directional contrast and directional vector is introduced in the measurement of pixel clarity. Finally based on pixel clarity of the corresponding pixels of the source images, a selection principle is put forward for fusion. Experimental results demonstrated that the proposed method could not only extract more important visual information from source images, but also effectively avoid the introduction of artificial information. It significantly outperforms the traditional image fusion methods.%针对非下采样Contourlet变换等多分辨率方法在图像融合过程中需要对源图像进行分解和重构,有可能改变源图像可靠信息等问题,提出了一种基于像素清晰度的NSCT的空域多聚焦图像融合方法.该方法根据HVS对局部对比度的敏感性和方向选择性,以及有用信息和噪声在NSCT域中的分布特点,引入局部方向对比度和方向向量的概念,用于衡量像素清晰度;然后通过比较多聚焦图像相应位置像素的清晰度,以选择模式决定融合图像的像素取自哪幅源图像.实验结果表明,该方法不仅能够从源图像中提取更多的有用信息,而且能够避免人为信息或高频噪声的引入,图像融合效果优于传统方法.

  8. Effect of Pixel's Spatial Characteristics on Recognition of Isolated Pixelized Chinese Character.

    Science.gov (United States)

    Yang, Kun; Liu, Shuang; Wang, Hong; Liu, Wei; Wu, Yaowei

    2015-01-01

    The influence of pixel's spatial characteristics on recognition of isolated Chinese character was investigated using simulated prosthestic vision. The accuracy of Chinese character recognition with 4 kinds of pixel number (6*6, 8*8, 10*10, and 12*12 pixel array) and 3 kinds of pixel shape (Square, Dot and Gaussian) and different pixel spacing were tested through head-mounted display (HMD). A captured image of Chinese characters in font style of Hei were pixelized with Square, Dot and Gaussian pixel. Results showed that pixel number was the most important factor which could affect the recognition of isolated pixelized Chinese Chartars and the accuracy of recognition increased with the addition of pixel number. 10*10 pixel array could provide enough information for people to recognize an isolated Chinese character. At low resolution (6*6 and 8*8 pixel array), there were little difference of recognition accuracy between different pixel shape and different pixel spacing. While as for high resolution (10*10 and 12*12 pixel array), the fluctuation of pixel shape and pixel spacing could not affect the performance of recognition of isolated pixelized Chinese Character.

  9. HISTOGRAM TECHNIQUE WITH PIXEL INDICATOR FOR HIGH FIDELITY STEGANOGRAPHY

    Directory of Open Access Journals (Sweden)

    V.Meiamai

    2013-06-01

    Full Text Available In this current world of increasing technology trends and the “internet age”, the security of our personal information has become more important than it has ever been there are media reports ofidentity theft and fraud and the numbers of innocent victims are increasing exponentially. Steganography plays an important role in preventing such information destruction by implementing a principle ofimperceptible secret sharing. By this security can be established by clearly embedding data in such a way that the quality of the image is not affected. The existing methodology prevailing now is based on pixel indicator and number of data to be embedded is by pixel value differencing technique. A limitation in this methodology is that the pixel indicator channel is manually selected. The proposed methodology uses pixel indicator channel which is decided using histogram technique and the secret message file has to be embedded in the plane which has the highest color intensity.

  10. Two-dimensional pixel array image sensor for protein crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Beuville, E.; Beche, J.-F.; Cork, C. [and others

    1996-07-01

    A 2D pixel array image sensor module has been designed for time resolved Protein Crystallography. This smart pixels detector significantly enhances time resolved Laue Protein crystallography by two to three orders of magnitude compared to existing sensors like films or phosphor screens coupled to CCDs. The resolution in time and dynamic range of this type of detector will allow one to study the evolution of structural changes that occur within the protein as a function of time. This detector will also considerably accelerate data collection in static Laue or monochromatic crystallography and make better use of the intense beam delivered by synchrotron light sources. The event driven pixel array detectors, based on the column Architecture, can provide multiparameter information (energy discrimination, time), with sparse and frameless readout without significant dead time. The prototype module consists of a 16x16 pixel diode array bump-bonded to the integrated circuit. The detection area is 150x150 square microns.

  11. The ATLAS Silicon Pixel Sensors

    CERN Document Server

    Alam, M S; Einsweiler, K F; Emes, J; Gilchriese, M G D; Joshi, A; Kleinfelder, S A; Marchesini, R; McCormack, F; Milgrome, O; Palaio, N; Pengg, F; Richardson, J; Zizka, G; Ackers, M; Andreazza, A; Comes, G; Fischer, P; Keil, M; Klasen, V; Kühl, T; Meuser, S; Ockenfels, W; Raith, B; Treis, J; Wermes, N; Gössling, C; Hügging, F G; Wüstenfeld, J; Wunstorf, R; Barberis, D; Beccherle, R; Darbo, G; Gagliardi, G; Gemme, C; Morettini, P; Musico, P; Osculati, B; Parodi, F; Rossi, L; Blanquart, L; Breugnon, P; Calvet, D; Clemens, J-C; Delpierre, P A; Hallewell, G D; Laugier, D; Mouthuy, T; Rozanov, A; Valin, I; Aleppo, M; Caccia, M; Ragusa, F; Troncon, C; Lutz, Gerhard; Richter, R H; Rohe, T; Brandl, A; Gorfine, G; Hoeferkamp, M; Seidel, SC; Boyd, GR; Skubic, P L; Sícho, P; Tomasek, L; Vrba, V; Holder, M; Ziolkowski, M; D'Auria, S; del Papa, C; Charles, E; Fasching, D; Becks, K H; Lenzen, G; Linder, C

    2001-01-01

    Prototype sensors for the ATLAS silicon pixel detector have been developed. The design of the sensors is guided by the need to operate them in the severe LHC radiation environment at up to several hundred volts while maintaining a good signal-to-noise ratio, small cell size, and minimal multiple scattering. The ability to be operated under full bias for electrical characterization prior to the attachment of the readout integrated circuit electronics is also desired.

  12. SAR Image Complex Pixel Representations

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Complex pixel values for Synthetic Aperture Radar (SAR) images of uniform distributed clutter can be represented as either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values. Generally, these component values are integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  13. An adaptive regression method for infrared blind-pixel compensation

    Science.gov (United States)

    Chen, Suting; Meng, Hao; Pei, Tao; Zhang, Yanyan

    2017-09-01

    Blind pixel compensation is an ill-posed inverse problem of infrared imaging systems and image restoration. The performance of a blind pixel compensation algorithm depends on the accuracy of estimation for the underlying true infrared images. We propose an adaptive regression method (ARM) for blind pixel compensation that integrates the multi-scale framework with a regression model. A blind-pixel is restored by exploiting the intra-scale properties through the nonparametric regressive estimation and the inter-scale characteristics via parametric regression for continuous learning. Combining the respective strengths of a parametric model and a nonparametric model, ARM establishes a set of multi-scale blind-pixel compensation method to correct the non-uniformity based on key frame extraction. Therefore, it is essentially different from the traditional frameworks for blind pixel compensation which are based on filtering and interpolation. Experimental results on some challenging cases of blind compensation show that the proposed algorithm outperforms existing methods by a significant margin in both isolated blind restoration and clustered blind restoration.

  14. PK-SVD Filter for Impulse Noise Based on Non-noisy Pixel Reconstruction%基于非噪声像素重构的PK-SVD脉冲噪声滤波

    Institute of Scientific and Technical Information of China (English)

    黄宴委; 祁冰露

    2014-01-01

    An improved K-SVD method based on non-noisy pixel reconstruction ( PK-SVD) is proposed to filter impulse noise. In the phase of image reconstruction, non-noisy pixels are applied in the construction of optimal function to obtain the reconstructed image and improve the filtering performance, and the optimal function is solved by integrating the hierarchical property into the OMP algorithm. In the phase of dictionary training, PK-SVD uses the iterant K-singular value decomposition to renovate both atoms and their coefficients rather than fixes the coefficients. The simulation results show that compared with the other three methods, PK-SVD obtains the sparsest dictionary and the clearest image with higher peak signal to noise ratio.%提出一种基于非噪声像素重构的K-SVD( Pixel K-SVD)脉冲噪声滤波方法。在图像重构阶段,以非噪声点像素值为优化目标,利用分层重构改进OMP算法求解优化函数,获得重构图像以提高恢复图像质量;在字典训练阶段,PK-SVD不再固定原子的系数,而是使用重复奇异值分解同时更新原子和系数。将PK-SVD与其他3种方法进行比较,实验结果表明,PK-SVD能得到最稀疏化的字典,较好地抑制脉冲噪声,使得滤波图像较清晰且具有较高的峰值信噪比。

  15. Optical Cloud Pixel Recovery via Machine Learning

    Directory of Open Access Journals (Sweden)

    Subrina Tahsin

    2017-05-01

    Full Text Available Remote sensing derived Normalized Difference Vegetation Index (NDVI is a widely used index to monitor vegetation and land use change. NDVI can be retrieved from publicly available data repositories of optical sensors such as Landsat, Moderate Resolution Imaging Spectro-radiometer (MODIS and several commercial satellites. Studies that are heavily dependent on optical sensors are subject to data loss due to cloud coverage. Specifically, cloud contamination is a hindrance to long-term environmental assessment when using information from satellite imagery retrieved from visible and infrared spectral ranges. Landsat has an ongoing high-resolution NDVI record starting from 1984. Unfortunately, this long time series NDVI data suffers from the cloud contamination issue. Though both simple and complex computational methods for data interpolation have been applied to recover cloudy data, all the techniques have limitations. In this paper, a novel Optical Cloud Pixel Recovery (OCPR method is proposed to repair cloudy pixels from the time-space-spectrum continuum using a Random Forest (RF trained and tested with multi-parameter hydrologic data. The RF-based OCPR model is compared with a linear regression model to demonstrate the capability of OCPR. A case study in Apalachicola Bay is presented to evaluate the performance of OCPR to repair cloudy NDVI reflectance. The RF-based OCPR method achieves a root mean squared error of 0.016 between predicted and observed NDVI reflectance values. The linear regression model achieves a root mean squared error of 0.126. Our findings suggest that the RF-based OCPR method is effective to repair cloudy pixels and provides continuous and quantitatively reliable imagery for long-term environmental analysis.

  16. The Dexela 2923 CMOS X-ray detector: A flat panel detector based on CMOS active pixel sensors for medical imaging applications

    Science.gov (United States)

    Konstantinidis, Anastasios C.; Szafraniec, Magdalena B.; Speller, Robert D.; Olivo, Alessandro

    2012-10-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors (APS) have been introduced recently in many scientific applications. This work reports on the performance (in terms of signal and noise transfer) of an X-ray detector that uses a novel CMOS APS which was developed for medical X-ray imaging applications. For a full evaluation of the detector's performance, electro-optical and X-ray characterizations were carried out. The former included measuring read noise, full well capacity and dynamic range. The latter, which included measuring X-ray sensitivity, presampling modulation transfer function (pMTF), noise power spectrum (NPS) and the resulting detective quantum efficiency (DQE), was assessed under three beam qualities (28 kV, 50 kV (RQA3) and 70 kV (RQA5) using W/Al) all in accordance with the IEC standard. The detector features an in-pixel option for switching the full well capacity between two distinct modes, high full well (HFW) and low full well (LFW). Two structured CsI:Tl scintillators of different thickness (a “thin” one for high resolution and a thicker one for high light efficiency) were optically coupled to the sensor array to optimize the performance of the system for different medical applications. The electro-optical performance evaluation of the sensor results in relatively high read noise (∼360 e-), high full well capacity (∼1.5×106 e-) and wide dynamic range (∼73 dB) under HFW mode operation. When the LFW mode is used, the read noise is lower (∼165) at the expense of a reduced full well capacity (∼0.5×106 e-) and dynamic range (∼69 dB). The maximum DQE values at low frequencies (i.e. 0.5 lp/mm) are high for both HFW (0.69 for 28 kV, 0.71 for 50 kV and 0.75 for 70 kV) and LFW (0.69 for 28 kV and 0.7 for 50 kV) modes. The X-ray performance of the studied detector compares well to that of other mammography and general radiography systems, obtained under similar experimental conditions. This demonstrates the suitability

  17. Mapping Electrical Crosstalk in Pixelated Sensor Arrays

    Science.gov (United States)

    Seshadri, Suresh (Inventor); Cole, David (Inventor); Smith, Roger M (Inventor); Hancock, Bruce R. (Inventor)

    2013-01-01

    The effects of inter pixel capacitance in a pixilated array may be measured by first resetting all pixels in the array to a first voltage, where a first image is read out, followed by resetting only a subset of pixels in the array to a second voltage, where a second image is read out, where the difference in the first and second images provide information about the inter pixel capacitance. Other embodiments are described and claimed.

  18. Mapping Electrical Crosstalk in Pixelated Sensor Arrays

    Science.gov (United States)

    Seshadri, Suresh (Inventor); Cole, David (Inventor); Smith, Roger M. (Inventor); Hancock, Bruce R. (Inventor)

    2017-01-01

    The effects of inter pixel capacitance in a pixilated array may be measured by first resetting all pixels in the array to a first voltage, where a first image is read out, followed by resetting only a subset of pixels in the array to a second voltage, where a second image is read out, where the difference in the first and second images provide information about the inter pixel capacitance. Other embodiments are described and claimed.

  19. 碲锌镉面元辐射探测器堆积载流子屏蔽效应%Accumulated-carrier screening effect based investigation for pixellated CdZnTe radiation detector

    Institute of Scientific and Technical Information of China (English)

    肖沙里; 黎淼; 王玺; 曹玉琳; 陈宇晓; 聂玲; 张流强

    2011-01-01

    Using the pixellated CdZnTe detector, the radiation imaging experiment for the Rh target X-ray source was accomplished. The experimental results indicate that the response signals of the anode pixels, which distribute over the center irradiated area, are completely shut-off when the tube voltage is 45 kV and the tube current increases to 20 μA. Moreover, the non-response pixel area expands with the increase of the tube current, and the total event count of the CdZnTe detector reduces obviously. Furthermore, the inner electric potential and electric field distributions of the pixellated CdZnTe detector were simulated based on the Poisson equation. The simulation results reveal that the accumulation of the hole carriers, which results from the extremely low drift ability of the hole carrier, leads to a relatively high space-charge-density area in the CdZnTe bulk when the irradiated photon flux increases to 5× 105 mm-2 · s-1. And thus, the induced signal screen effect of the anode pixels in the center irradiated area is mainly attributed to the distorted electric field which makes electron carriers drift toward the high potential area in the CdZnTe crystal instead of the pixel anodes.%采用铑(Rh)靶45 kV X射线源进行了碲锌镉(CdZnTe)面元像素阵列探测器成像实验.实验结果表明:在探测距离1 mm,管电压45 kV条件下,管电流增大至20μA时,辐照中心区域像素单元信号丢失,出现围绕辐照中心区域的边缘高事件计数环形探测图像.随着管电流的增大,无响应像素区域扩大,探测器总体事件计数明显降低.进一步根据泊松方程建立了CdZnTe晶体内部电势分布模型,仿真结果表明:单位面积光子通量为5×105 mm-2·s-1时,由于CdZnTe晶体较低的空穴迁移率,晶体内部存在堆积空穴载流子形成的高空间电荷密度分布区域.晶体内部电场产生扭曲,电子载流子无法迁移至对应阳极位置,导致辐照中心区域产生信号屏蔽效应.

  20. 基于混合像元分解的天山典型地区冰雪变化监测%Monitoring of Snow Cover Changes in Tianshan Mountains Based on Mixed Pixel Decomposition

    Institute of Scientific and Technical Information of China (English)

    金鑫; 柯长青

    2012-01-01

    针对中低分辨率遥感图像中存在大量混合像元,而传统的图像分类方法存在只能将某个像元归到某一类中,不能正确反映混合像元实际情况的问题.以新疆天山典型冰川覆盖区为例,根据TM/ETM+遥感图像的光谱特征,结合天山地区地表覆盖特点,在线性混合像元分解方法基础上,设计一种符合冰川地区特点的“冰雪-植被-裸露山体-阴影”端元组分模型.通过选择合适的端元并将其反射率值代入改进后的且满足约束条件的线性混合像元分解模型,得到各端元组分丰度图,进而精确提取出冰雪信息并计算其面积.1989年TM和2000年ETM+遥感图像冰雪信息提取结果表明,运用线性混合像元分解模型能很好地监测实验区的冰雪覆盖变化情况.%Mixed pixels are abundant in medium - low resolution images, but the traditional methods for image classification could only assign pixels to one class,with the ignorance of the mixed pixels. To tackle this problem, the authors selected the typical area in Tianshan Glacier of Xinjiang as an experimental area. Based on the theory of mixed pixel decomposition and the principle of the linear model and taking into account the spectral characteristics of TM/ETM + image as well as the land cover characteristics of Tianshan area, the authors developed an end -member composition model suitable for the glacier area,i. e. , Snow - Vegetation - Rock - Shade model. After the appropriate end - members were selected and the reflectance values were substituted into the improved linear mixed pixel decomposition model, which satisfied the constraints, the abundance image of individual end - member was calculated and the snow cover information was easily and precisely extracted. The extraction results of snow cover in 1989 and 2000 demonstrate that the mixed pixel decomposition and the linear model could be used to monitor the snow cover changes in the glacier area.

  1. An Unsupervised Classification of Hyperspectral Images Based on Pixels Reduction with Spatial Coherence Property%一种基于空间一致性降元的高光谱图像非监督分类

    Institute of Scientific and Technical Information of China (English)

    岳江; 张毅; 徐杭威; 柏连发

    2012-01-01

    为了提高分类精度和边缘辨识性,该文引入图像空间一致性降元(pixels reduction with spatial coherence property,PRSCP)及线性回归分析,提出了一种基于空间一致性降元的非监督分类.该方法从像元光谱相似性出发,利用像元最小关联窗口合并相邻相似像元为像块完成降元.使用线性关系建模像块内像元的光谱向量,并利用F检验判断像块数据的线性显著性.利用一元线性回归(one dimensional linear regression,ODLR)估计出像块的基准向量,根据基准向最合并相似(同类)像块完成分类.利用AVIRIS数据评估了该方法性能,实验结果表明:与K-MEANS和ISODATA方法相比,该方法精度高、边缘辨识度好及鲁棒性强.%In order to improve classification and edge accuracy, PRSCP and linear regression analysis are introduced; a new algorithm of unsupervised classification based on PRSCP is proposed. The algorithm procedure starts with the similarity of pixel spectral, and then makes use of minimum related window to combine similar pixels spatially adjacent into a block. Linear expression is applied to model the spectral vector of pixels in the same block, and significance of the linear expression is verified by F-statistic. The basic vector of block is estimated via ODLR, and blocks with similar basic vectors are combined into the same class. AVIRIS data is used to evaluate the performance of the proposed algorithm, which is also compared with K-MEANS and ISODATA. Experimental results show that the proposed algorithm outperforms K-MEANS and ISODATA in terms of classification accuracy, edge and robustness.

  2. CVD diamond pixel detectors for LHC experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wedenig, R.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knoepfle, K.T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L.S.; Palmieri, V.G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A.M.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M.; Blanquart, L.; Breugnion, P.; Charles, E.; Ciocio, A.; Clemens, J.C.; Dao, K.; Einsweiler, K.; Fasching, D.; Fischer, P.; Joshi, A.; Keil, M.; Klasen, V.; Kleinfelder, S.; Laugier, D.; Meuser, S.; Milgrome, O.; Mouthuy, T.; Richardson, J.; Sinervo, P.; Treis, J.; Wermes, N

    1999-08-01

    This paper reviews the development of CVD diamond pixel detectors. The preparation of the diamond pixel sensors for bump-bonding to the pixel readout electronics for the LHC and the results from beam tests carried out at CERN are described.

  3. CMS has a heart of pixels

    CERN Multimedia

    2003-01-01

    In the immediate vicinity of the collision point, CMS will be equipped with pixel detectors consisting of no fewer than 50 million pixels measuring 150 microns along each side. Each of the pixels, which receive the signal, is connected to its own electronic circuit by a tiny sphere (seen here in the electron microscope image) measuring 15 to 20 microns in diameter.

  4. A Novel Sensor Based on a Single-Pixel Microwave Radiometer for Warm Object Counting: Concept Validation and IoT Perspectives

    Directory of Open Access Journals (Sweden)

    Federico Alimenti

    2017-06-01

    Full Text Available Controlled measurements by a low-cost single-pixel microwave radiometer operating at 12.65 GHz were carried out to assess the detection and counting capability for targets warmer than the surroundings. The adopted reference test targets were pre-warmed water and oil; and a hand, both naked and wearing a glove. The results showed the reliability of microwave radiometry for counting operations under controlled conditions, and its effectiveness at detecting even warm targets masked by unheated dielectric layers. An electromagnetic model describing the scenario sensed by the radiometer antenna is proposed, and comparison with the experimental observations shows a good agreement. The measurements prove that reliable counting is enabled by an antenna temperature increment, for each target sample added, of around 1 K. Starting from this value, an analysis of the antenna filling factor was performed to provide an instrument useful for evaluating real applicability in many practical situations. This study also allows the direct people counting problem to be addressed, providing preliminary operational indications, reference numbers and experimental validation.

  5. A Novel Sensor Based on a Single-Pixel Microwave Radiometer for Warm Object Counting: Concept Validation and IoT Perspectives.

    Science.gov (United States)

    Alimenti, Federico; Bonafoni, Stefania; Roselli, Luca

    2017-06-14

    Controlled measurements by a low-cost single-pixel microwave radiometer operating at 12.65 GHz were carried out to assess the detection and counting capability for targets warmer than the surroundings. The adopted reference test targets were pre-warmed water and oil; and a hand, both naked and wearing a glove. The results showed the reliability of microwave radiometry for counting operations under controlled conditions, and its effectiveness at detecting even warm targets masked by unheated dielectric layers. An electromagnetic model describing the scenario sensed by the radiometer antenna is proposed, and comparison with the experimental observations shows a good agreement. The measurements prove that reliable counting is enabled by an antenna temperature increment, for each target sample added, of around 1 K. Starting from this value, an analysis of the antenna filling factor was performed to provide an instrument useful for evaluating real applicability in many practical situations. This study also allows the direct people counting problem to be addressed, providing preliminary operational indications, reference numbers and experimental validation.