Photoelectron extraction efficiency from a CsI photocathode and THGEM operation in He−CF4 and He−CH4 mixtures

International Nuclear Information System (INIS)

Coimbra, A.E.C.; Santos, J.M.F. dos; Israelashvili, I.

2016-01-01

This work presents the experimental measurements obtained for UV-induced photo-electron extraction efficiency from a CsI photocathode into He with CF 4 and CH 4 gas mixtures. A 1000Å CsI photocathode was deposited on a gold plated THGEM for photo-electron conversion. Charge-gain measurements were obtained with a Single-THGEM detector operating in these gas mixtures using a continuous UV lamp for the extraction of photo-electrons. Charge-gains in excess of 10 5 were obtained for gas mixtures containing percentages of quencher higher than 20% while photo-electron extraction efficiency achieved ∼ 50% for He/CF 4 and ∼ 30% for He/CH 4 . Single photon electron measurements were also performed to assess the maximal gains reached in this regime. A discussion for future GPM cryogenic applications is presented

X-ray detectors based on image sensors

International Nuclear Information System (INIS)

Costa, A.P.R.

1983-01-01

X-ray detectors based on image sensors are described and a comparison is made between the advantages and the disadvantages of such a kind of detectors with the position sensitive detectors. (L.C.) [pt

arXiv On the localization properties of an RPWELL gas-avalanche detector

CERN Document Server

Moleri, Luca; Coimbra, Artur E. C.; Breskin, Amos; Bressler, Shikma

2017-10-23

A study of the localization properties of a single-element Resistive Plate WELL (RPWELL) detector is presented. The detector comprises of a single-sided THick Gaseous Electron Multiplier (THGEM) coupled to a segmented readout anode through a doped silicate-glass plate of 10(10) Ω⋅cm bulk resistivity. Operated in ambient \

Radiation imaging with optically read out GEM-based detectors

Science.gov (United States)

Brunbauer, F. M.; Lupberger, M.; Oliveri, E.; Resnati, F.; Ropelewski, L.; Streli, C.; Thuiner, P.; van Stenis, M.

2018-02-01

Modern imaging sensors allow for high granularity optical readout of radiation detectors such as MicroPattern Gaseous Detectors (MPGDs). Taking advantage of the high signal amplification factors achievable by MPGD technologies such as Gaseous Electron Multipliers (GEMs), highly sensitive detectors can be realised and employing gas mixtures with strong scintillation yield in the visible wavelength regime, optical readout of such detectors can provide high-resolution event representations. Applications from X-ray imaging to fluoroscopy and tomography profit from the good spatial resolution of optical readout and the possibility to obtain images without the need for extensive reconstruction. Sensitivity to low-energy X-rays and energy resolution permit energy resolved imaging and material distinction in X-ray fluorescence measurements. Additionally, the low material budget of gaseous detectors and the possibility to couple scintillation light to imaging sensors via fibres or mirrors makes optically read out GEMs an ideal candidate for beam monitoring detectors in high energy physics as well as radiotherapy. We present applications and achievements of optically read out GEM-based detectors including high spatial resolution imaging and X-ray fluorescence measurements as an alternative readout approach for MPGDs. A detector concept for low intensity applications such as X-ray crystallography, which maximises detection efficiency with a thick conversion region but mitigates parallax-induced broadening is presented and beam monitoring capabilities of optical readout are explored. Augmenting high resolution 2D projections of particle tracks obtained with optical readout with timing information from fast photon detectors or transparent anodes for charge readout, 3D reconstruction of particle trajectories can be performed and permits the realisation of optically read out time projection chambers. Combining readily available high performance imaging sensors with compatible

The resistive plate WELL detector as a single stage thick gaseous multiplier detector

Energy Technology Data Exchange (ETDEWEB)

Bressler, Shikma; Breskin, Amos; Moleri, Luca; Kumar, Ashwini; Pitt, Michael [Department of Particle Physics and Astrophysics, Weizmann Institute of Science (WIS) (Israel); Kudella, Simon [Institut fuer Experimentelle Kernphysik (IEKP), KIT (Germany)

2015-07-01

Gaseous Electron Multiplier (GEM) detector use high electric fields inside the h ole of a foil to achieve a high charge multiplication. As a thicker version of G EMs based on printed circuit board (PCB) structures, Thick Gaseous Electron Multiplier (THGEM) detectors combine the high gain of a GEM foil with the robustness, stability and low production costs of a PCB and allow a large quantity of applications that require the coverage of a large area at low cost and moderate spatial resolution. One application the Weizmann Institute of Science (WIS) develops as a member of the RD51 framework is the Resistive Plate WELL (RPWELL) detector. This single stage detector allows a very stable, discharge free operation at high gain (10{sup 5}). The single stage operation allows a low total height and make s the RPWELL a candidate for the Digital Hadronic Calorimeter (DHCAL) of the International Large Detector (ILD) at the International Linear Collider (ILC). The talk gives an insight into the way the RPWELL works and shows results from the last test beam.

Development of a thick gas electron multiplier for microdosimetry

International Nuclear Information System (INIS)

Orchard, G.M.; Chin, K.; Prestwich, W.V.; Waker, A.J.; Byun, S.H.

2011-01-01

A new tissue-equivalent proportional counter based on a thick gas electron multiplier (THGEM) was developed and tested for microdosimetry. A systematic test was conducted at the McMaster Accelerator Laboratory to investigate the overall performance of the prototype detector. A mixed neutron-gamma-ray radiation field was generated using the 7 Li(p,n) reaction. The detector was operated at low voltage initially to test the stability and then the relative multiplication gain was measured as a function of the operating high voltage. A drift potential of 100 V and a THGEM bias of 727 V generated a multiplication gain sufficient for the detection of both neutron and gamma-ray radiation. A consistent microdosimetric pattern was observed between the THGEM detector and standard TEPC for microdosimetry.

Graphene-based ultrasonic detector for photoacoustic imaging

Science.gov (United States)

Yang, Fan; Song, Wei; Zhang, Chonglei; Fang, Hui; Min, Changjun; Yuan, Xiaocong

2018-03-01

Taking advantage of optical absorption imaging contrast, photoacoustic imaging technology is able to map the volumetric distribution of the optical absorption properties within biological tissues. Unfortunately, traditional piezoceramics-based transducers used in most photoacoustic imaging setups have inadequate frequency response, resulting in both poor depth resolution and inaccurate quantification of the optical absorption information. Instead of the piezoelectric ultrasonic transducer, we develop a graphene-based optical sensor for detecting photoacoustic pressure. The refractive index in the coupling medium is modulated due to photoacoustic pressure perturbation, which creates the variation of the polarization-sensitive optical absorption property of the graphene. As a result, the photoacoustic detection is realized through recording the reflectance intensity difference of polarization light. The graphene-based detector process an estimated noise-equivalentpressure (NEP) sensitivity of 550 Pa over 20-MHz bandwidth with a nearby linear pressure response from 11.0 kPa to 53.0 kPa. Further, a graphene-based photoacoustic microscopy is built, and non-invasively reveals the microvascular anatomy in mouse ears label-freely.

Development of a neutron imager based on superconducting detectors

Energy Technology Data Exchange (ETDEWEB)

Miyajima, Shigeyuki, E-mail: miyajima@nict.go.jp [Department of Physics and Engineering, Osaka Prefecture University (Japan); Institute for Nanofabrication Research, Osaka Prefecture University (Japan); Yamaguchi, Hiroyuki; Nakayama, Hirotaka; Shishido, Hiroaki [Department of Physics and Engineering, Osaka Prefecture University (Japan); Institute for Nanofabrication Research, Osaka Prefecture University (Japan); Fujimaki, Akira [Department of Quantum Engineering, Nagoya University (Japan); Hidaka, Mutsuo [National Institute of Advanced Industrial Science and Technology (Japan); Harada, Masahide; Oikawa, Kenichi; Oku, Takayuki; Arai, Masatoshi [J-PARC Center, Japan Atomic Energy Agency (Japan); Ishida, Takekazu [Department of Physics and Engineering, Osaka Prefecture University (Japan); Institute for Nanofabrication Research, Osaka Prefecture University (Japan)

2016-11-15

Highlights: • A neutron detector based on superconducting meander line is demonstrated. • Fast response time of a few tens ns is obtained. • Spatial resolution is 1 μm and can be improved to sub-μm scale. • The proposed neutron detector can operate under the γ-ray fields. - Abstract: We succeeded in demonstrating a neutron detector based on a Nb superconducting meander line with a {sup 10}B conversion layer for a neutron imager based on superconductor devices. We use a current-biased kinetic inductance detector (CB-KID), which is composed of a meander line, for detection of a neutron with high spatial resolution and fast response time. The thickness of Nb meander lines is 40 nm and the line width is narrower than 3 mu m. The area of 8 mm × 8 mm is covered by CB-KIDs, which are assembled at the center of the Si chip of the size 22 mm × 22 mm. The Nb CB-KIDs with a {sup 10}B conversion layer output the voltage by irradiating pulsed neutrons. We have investigated γ/n discrimination of a Nb-based CB-KID with {sup 10}B conversion layer using a Cd plate, which indicates that a CB-KID can operate as a neutron detector under the strong γ-ray fields.

Development of a neutron imager based on superconducting detectors

International Nuclear Information System (INIS)

Miyajima, Shigeyuki; Yamaguchi, Hiroyuki; Nakayama, Hirotaka; Shishido, Hiroaki; Fujimaki, Akira; Hidaka, Mutsuo; Harada, Masahide; Oikawa, Kenichi; Oku, Takayuki; Arai, Masatoshi; Ishida, Takekazu

2016-01-01

Highlights: • A neutron detector based on superconducting meander line is demonstrated. • Fast response time of a few tens ns is obtained. • Spatial resolution is 1 μm and can be improved to sub-μm scale. • The proposed neutron detector can operate under the γ-ray fields. - Abstract: We succeeded in demonstrating a neutron detector based on a Nb superconducting meander line with a "1"0B conversion layer for a neutron imager based on superconductor devices. We use a current-biased kinetic inductance detector (CB-KID), which is composed of a meander line, for detection of a neutron with high spatial resolution and fast response time. The thickness of Nb meander lines is 40 nm and the line width is narrower than 3 mu m. The area of 8 mm × 8 mm is covered by CB-KIDs, which are assembled at the center of the Si chip of the size 22 mm × 22 mm. The Nb CB-KIDs with a "1"0B conversion layer output the voltage by irradiating pulsed neutrons. We have investigated γ/n discrimination of a Nb-based CB-KID with "1"0B conversion layer using a Cd plate, which indicates that a CB-KID can operate as a neutron detector under the strong γ-ray fields.

Novel gaseous detectors for medical imaging

International Nuclear Information System (INIS)

Danielsson, M.; Fonte, P.; Francke, T.; Iacobaeus, C.; Ostling, J.; Peskov, V.

2004-01-01

We have developed and successfully tested prototypes of two new types of gaseous detectors for medical imaging purposes. The first one is called the Electronic Portal Imaging Device (EPID). It is oriented on monitoring and the precise alignment of the therapeutic cancer treatment beam (pulsed gamma radiation) with respect to the patient's tumor position. The latest will be determined from an X-ray image of the patient obtained in the time intervals between the gamma pulses. The detector is based on a 'sandwich' of hole-type gaseous detectors (GEM and glass microcapillary plates) with metallic gamma and X-ray converters coated with CsI layers. The second detector is an X-ray image scanner oriented on mammography and other radiographic applications. It is based on specially developed by us high rate RPCs that are able to operate at rates of 10 5 Hz/mm 2 with a position resolution better than 50 μm at 1 atm. The quality of the images obtained with the latest version of this device were in most cases more superior than those obtained from commercially available detectors

Characterization of LiF-based soft X-ray imaging detectors by confocal fluorescence microscopy

International Nuclear Information System (INIS)

Bonfigli, F; Gaudio, P; Lupelli, I; Nichelatti, E; Richetta, M; Vincenti, M A; Montereali, R M

2010-01-01

X-ray microscopy represents a powerful tool to obtain images of samples with very high spatial resolution. The main limitation of this technique is represented by the poor spatial resolution of standard imaging detectors. We proposed an innovative high-performance X-ray imaging detector based on the visible photoluminescence of colour centres in lithium fluoride. In this work, a confocal microscope in fluorescence mode was used to characterize LiF-based imaging detectors measuring CC integrated visible fluorescence signals of LiF crystals and films (grown on several kinds of substrates) irradiated by soft X-rays produced by a laser plasma source in different exposure conditions. The results are compared with the CC photoluminescence spectra measured on the same samples and discussed.

Polymer fiber detectors for photoacoustic imaging

Science.gov (United States)

Grün, Hubert; Berer, Thomas; Pühringer, Karoline; Nuster, Robert; Paltauf, Günther; Burgholzer, Peter

2010-02-01

Photoacoustic imaging is a novel imaging method for medical and biological applications, combining the advantages of Diffuse Optical Imaging (high contrast) and Ultrasonic Imaging (high spatial resolution). A short laser pulse hits the sample. The absorbed energy causes a thermoelastic expansion and thereby launches a broadband ultrasonic wave (photoacoustic signal). The distribution of absorbed energy density is reconstructed from measurements of the photoacoustic signals around the sample. For collecting photoacoustic signals either point like or extended, integrating detectors can be used. The latter integrate the pressure at least in one dimension, e.g. along a line. Thereby, the three dimensional imaging problem is reduced to a two dimensional problem. For a tomography device consisting of a scanning line detector and a rotating sample, fiber-based detectors made of polymer have been recently introduced. Fiber-based detectors are easy to use and possess a constant, high spatial resolution over their entire active length. Polymer fibers provide a better impedance matching and a better handling compared with glass fibers which were our first approach. First measurement results using polymer fiber detectors and some approaches for improving the performance are presented.

Space imaging measurement system based on fixed lens and moving detector

Science.gov (United States)

Akiyama, Akira; Doshida, Minoru; Mutoh, Eiichiro; Kumagai, Hideo; Yamada, Hirofumi; Ishii, Hiromitsu

2006-08-01

We have developed the Space Imaging Measurement System based on the fixed lens and fast moving detector to the control of the autonomous ground vehicle. The space measurement is the most important task in the development of the autonomous ground vehicle. In this study we move the detector back and forth along the optical axis at the fast rate to measure the three-dimensional image data. This system is just appropriate to the autonomous ground vehicle because this system does not send out any optical energy to measure the distance and keep the safety. And we use the digital camera of the visible ray range. Therefore it gives us the cost reduction of the three-dimensional image data acquisition with respect to the imaging laser system. We can combine many pieces of the narrow space imaging measurement data to construct the wide range three-dimensional data. This gives us the improvement of the image recognition with respect to the object space. To develop the fast movement of the detector, we build the counter mass balance in the mechanical crank system of the Space Imaging Measurement System. And then we set up the duct to prevent the optical noise due to the ray not coming through lens. The object distance is derived from the focus distance which related to the best focused image data. The best focused image data is selected from the image of the maximum standard deviation in the standard deviations of series images.

Intravascular imaging with a storage phosphor detector

Energy Technology Data Exchange (ETDEWEB)

Shikhaliev, Polad M; Petrek, Peter; Matthews, Kenneth L II; Fritz, Shannon G [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA (United States); Bujenovic, L Steven [PET Imaging Center, Our Lady of the Lake Medical Center, Baton Rouge, LA (United States); Xu Tong, E-mail: pshikhal@lsu.ed [Department of Physics, Carleton University, Ottawa (Canada)

2010-05-21

The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm{sup 3} volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 {mu}Ci cm{sup -3} activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm{sup -2} were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360{sup 0} circumference. Spatial

A Monte Carlo simulation of the microdosimetric response for thick gas electron multiplier

International Nuclear Information System (INIS)

Hanu, A.; Byun, S.H.; Prestwich, W.V.

2010-01-01

The neutron microdosimetric responses of the thick gas electron multiplier (THGEM) detector were simulated. The THGEM is a promising device for microdosimetry, particularly for measuring the dose spectra of intense radiation fields and for collecting two-dimensional microdosimetric distributions. To investigate the response of the prototype THGEM microdosimetric detector, a simulation was developed using the Geant4 Monte Carlo code. The simulation calculates the deposited energy in the detector sensitive volume for an incident neutron beam. Both neutron energy and angular responses were computed for various neutron beam conditions. The energy response was compared with the reported experimental microdosimetric spectra as well as the evaluated fluence-to-kerma conversion coefficients. The effects of using non-tissue equivalent materials were also investigated by comparing the THGEM detector response with the response of an ideal detector in identical neutron field conditions. The result of the angular response simulations revealed severe angular dependencies for neutron energies above 100 keV. The simulation of a modified detector design gave an angular response pattern close to the ideal case, showing a fluctuation of less than 10% over the entire angular range.

X-ray detectors in medical imaging

International Nuclear Information System (INIS)

Spahn, Martin

2013-01-01

Healthcare systems are subject to continuous adaptation, following trends such as the change of demographic structures, the rise of life-style related and chronic diseases, and the need for efficient and outcome-oriented procedures. This also influences the design of new imaging systems as well as their components. The applications of X-ray imaging in the medical field are manifold and have led to dedicated modalities supporting specific imaging requirements, for example in computed tomography (CT), radiography, angiography, surgery or mammography, delivering projection or volumetric imaging data. Depending on the clinical needs, some X-ray systems enable diagnostic imaging while others support interventional procedures. X-ray detector design requirements for the different medical applications can vary strongly with respect to size and shape, spatial resolution, frame rates and X-ray flux, among others. Today, integrating X-ray detectors are in common use. They are predominantly based on scintillators (e.g. CsI or Gd 2 O 2 S) and arrays of photodiodes made from crystalline silicon (Si) or amorphous silicon (a-Si) or they employ semiconductors (e.g. Se) with active a-Si readout matrices. Ongoing and future developments of X-ray detectors will include optimization of current state-of-the-art integrating detectors in terms of performance and cost, will enable the usage of large size CMOS-based detectors, and may facilitate photon counting techniques with the potential to further enhance performance characteristics and foster the prospect of new clinical applications

Design optimization of a breast imaging system based on silicon microstrip detectors

International Nuclear Information System (INIS)

Stres, S.; Mikuz, M.

2000-01-01

A mammographic imaging set-up using silicon microstrip detectors in edge-on geometry was simulated using the GEANT package. Deposited energy in tissue of various thicknesses was evaluated and shown to agree to within 10% with reference calculations. Optimal energies as well as spectra for mammography with silicon detectors were determined by maximizing the figure of merit of a realistic imaging set-up. The scattered to primary radiation ratio was studied for various detector geometries. It was found that fan-shaped detectors are needed to maintain the image quality for divergent photon beams. (author)

Amorphous selenium based detectors for medical imaging applications

Science.gov (United States)

Mandal, Krishna C.; Kang, Sung H.; Choi, Michael; Jellison, Gerald E., Jr.

2006-08-01

We have developed and characterized large volume amorphous (a-) selenium (Se) stabilized alloys for room temperature medical imaging devices and high-energy physics detectors. The synthesis and preparation of well-defined and high quality a-Se (B, As, Cl) alloy materials have been conducted using a specially designed alloying reactor at EIC and installed in an argon atmosphere glove box. The alloy composition has been precisely controlled and optimized to ensure good device performance. The synthesis of large volume boron (B) doped (natural and isotopic 10B) a-Se (As, Cl) alloys has been carried out by thoroughly mixing vacuum distilled and zone-refined (ZR) Se with previously synthesized Se-As master alloys, Se-Cl master alloys and B. The synthesized a-Se (B, As, Cl) alloys have been characterized by x-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infra-red spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectroscopy (ICP-MS), and detector testing. The a- Se alloys have shown high promise for x-ray detectors with its high dark resistivity (10 10-10 13 Ωcm), good charge transport properties, and cost-effective large area scalability. Details of various steps about detector fabrication and testing of these imaging devices are also presented.

Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

Science.gov (United States)

Cha, B. K.; Kim, J. Y.; Kim, Y. J.; Yun, S.; Cho, G.; Kim, H. K.; Seo, C.-W.; Jeon, S.; Huh, Y.

2012-04-01

In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator-based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm2 active area and a 48 μm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

New medical imaging systems exploiting the energy dispersive X-ray diffraction with spectrometric CdZnTe based detector

International Nuclear Information System (INIS)

Barbes, Damien

2016-01-01

This thesis studies the interest of measuring the coherent scattering of X-rays for breast diagnosis imaging. Nowadays, most of X-ray-based medical imaging techniques use the information of X-rays attenuation through the tissues. It is the case for mammography, the most common breast imaging modality. The recent emergence of energy resolved detectors (based on semiconductors in particular) allows to consider using another phenomenon: the coherent X-ray scattering. Measurement of diffracted spectra can provide new information related to the molecular structure of the examined tissues, in order to improve their characterization and therefore improve the final diagnosis. Two modalities are considered: the breast cancer detection in vivo, following a suspicious mammography result, or biopsy analysis. The coherent scattering measurement system developed during this thesis work uses energy-resolved CdZnTe-based detectors, these detectors combining performances (energy resolution, sensitivity, spatial resolution, and compactness) promising for clinical application. This system is also based on the detector pixelation, which allows to provide an imaging modality capable of characterizing analyzed materials or tissues in one direction without any translation or rotation. A complete study of the measurement system is proposed in this thesis, structured in three main parts: modeling and simulation of the system, development of the processing of the data measured by the detector in order to image and characterize the analyzed sample and finally, designing of a new and more complex experimental setup based on a whole detector and multi-slit collimation system. An experimental validation is proposed for each of these three parts. (author) [fr

18th International Workshop on Radiation Imaging Detectors

CERN Document Server

2016-01-01

The International Workshops on Radiation Imaging Detectors are held yearly and provide an international forum for discussing current research and developments in the area of position sensitive detectors for radiation imaging, including semiconductor detectors, gas and scintillator-based detectors. Topics include processing and characterization of detector materials, hybridization and interconnect technologies, design of counting or integrating electronics, readout and data acquisition systems, and applications in various scientific and industrial fields. The workshop will have plenary sessions with invited and contributed papers presented orally and in poster sessions. The invited talks will be chosen to review recent advances in different areas covered in the workshop.

GATE simulation of a LYSO-based SPECT imager: Validation and detector optimization

International Nuclear Information System (INIS)

Li, Suying; Zhang, Qiushi; Xie, Zhaoheng; Liu, Qi; Xu, Baixuan; Yang, Kun; Li, Changhui; Ren, Qiushi

2015-01-01

This paper presents a small animal SPECT system that is based on cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal, position sensitive photomultiplier tubes (PSPMTs) and parallel hole collimator. Spatial resolution test and animal experiment were performed to demonstrate the imaging performance of the detector. Preliminary results indicated a spatial resolution of 2.5 mm at FWHM that cannot meet our design requirement. Therefore, we simulated this gamma camera using GATE (GEANT 4 Application for Tomographic Emission) aiming to make detector spatial resolution less than 2 mm. First, the GATE simulation process was validated through comparison between simulated and experimental data. This also indicates the accuracy and effectiveness of GATE simulation for LYSO-based gamma camera. Then the different detector sampling methods (crystal size with 1.5, and 1 mm) and collimator design (collimator height with 30, 34.8, 38, and 43 mm) were studied to figure out an optimized parameter set. Detector sensitivity changes were also focused on with different parameters set that generated different spatial resolution results. Tradeoff curves of spatial resolution and sensitivity were plotted to determine the optimal collimator height with different sampling methods. Simulation results show that scintillation crystal size of 1 mm and collimator height of 38 mm, which can generate a spatial resolution of ∼1.8 mm and sensitivity of ∼0.065 cps/kBq, can be an ideal configuration for our SPECT imager design

A gamma-ray tracking detector for molecular imaging

International Nuclear Information System (INIS)

Hall, C.J.; Lewis, R.A.; Helsby, W.I.; Nolan, P.; Boston, A.

2003-01-01

A design for a gamma-ray detector for molecular imaging is presented. The system is based on solid-state strip detector technology. The advantages of position sensitivity coupled with fine spectral resolution are exploited to produce a tracking detector for use with a variety of isotopes in nuclear medicine. Current design concepts employ both silicon and germanium layers to provide an energy range from 60 keV to >1 MeV. This allows a reference X-ray image to be collected simultaneously with the gamma-ray image providing accurate anatomical registration. The tracking ability of the gamma-ray detector allows ambiguities in the data set to be resolved which would otherwise cause events to be rejected in standard non-tracking system. Efficiency improvements that high solid angle coverage and the use of a higher proportion of events make time resolved imaging and multi-isotope work possible. A modular detector system, designed for viewing small animals has been accepted for funding

Ultrafast secondary emission x-ray imaging detectors

International Nuclear Information System (INIS)

Akkerman, A.; Gibrekhterman, A.; Majewski, S.

1991-07-01

Fast high accuracy, x-ray imaging at high photon flux can be achieved when coupling thin solid convertors to gaseous electron multipliers, operating at low gas pressures. Secondary electron emitted from the convertor foil are multiplied in several successive amplification elements. The obvious advantage of solid x-ray detectors, as compared to gaseous conversion, are the production of parallax-free images and the fast (subnanoseconds) response. These x-ray detectors have many potential applications in basic and applied research. Of particular interest is the possibility of an efficient and ultrafast high resolution imaging of transition radiation,with a reduced dE/dx background. We present experimental results on the operation of the secondary emission x-ray (SEX) detectors, their detection efficiency, localization and time resolution. The experimental work is accompanied by mathematical modelling and computer simulation of transition radiation detectors based on CsI transition radiation convertors. (author)

The Resistive-Plate WELL with Argon mixtures - a robust gaseous radiation detector

CERN Document Server

Moleri, Luca; Arazi, Lior; Rocha Azevedo, Carlos Davide; Oliveri, Eraldo; Pitt, Michael; Schaarschmidt, Jana; Shaked-Renous, Dan; Marques Ferreira dos Santos, Joaquim; Veloso, Joao Filipe Calapez de Albuquerque; Breskin, Amos; Bressler, Shikma

2017-01-01

A thin single-element THGEM-based, Resistive-Plate WELL (RPWELL) detector was operated with 150 GeV/c muon and pion beams in Ne/(5%CH$_4$), Ar/(5%CH$_4$) and Ar/(7%CO$_2$); signals were recorded with 1 cm$^2$ square pads and SRS/APV25 electronics. Detection efficiency values greater than 98% were reached in all the gas mixtures, at average pad multiplicity of 1.2. The use of the 10$^9${\\Omega}cm resistive plate resulted in a completely discharge-free operation also in intense pion beams. The efficiency remained essentially constant at 98-99% up to fluxes of $\\sim$10$^4$Hz/cm$^2$, dropping by a few % when approaching 10$^5$ Hz/cm$^2$. These results pave the way towards cost-effective, robust, efficient, large-scale detectors for a variety of applications in future particle, astro-particle and applied fields. A potential target application is digital hadron calorimetry.

Neutron beam imaging with GEM detectors

International Nuclear Information System (INIS)

Albani, G.; Cazzaniga, C.; Rebai, M.; Gorini, G.; Croci, G.; Muraro, A.; Cippo, E. Perelli; Tardocchi, M.; Cavenago, M.; Murtas, F.; Claps, G.; Pasqualotto, R.

2015-01-01

Neutron GEM-based detectors represent a new frontier of devices in neutron physics applications where a very high neutron flux must be measured such as future fusion experiments (e.g. ITER Neutral beam Injector) and spallation sources (e.g. the European Spallation source). This kind of detectors can be properly adapted to be used both as beam monitors but also as neutron diffraction detectors that could represent a valid alternative for the 3 He detectors replacement. Fast neutron GEM detectors (nGEM) feature a cathode composed by one layer of polyethylene and one of aluminium (neutron scattering on hydrogen generates protons that are detected in the gas) while thermal neutron GEM detectors (bGEM) are equipped with a borated aluminium cathode (charged particles are generated through the 10 B(n,α) 7 Li reaction). GEM detectors can be realized in large area (1 m 2 ) and their readout can be pixelated. Three different prototypes of nGEM and one prototype of bGEM detectors of different areas and equipped with different types of readout have been built and tested. All the detectors have been used to measure the fast and thermal neutron 2D beam image at the ISIS-VESUVIO beamline. The different kinds of readout patterns (different areas of the pixels) have been compared in similar conditions. All the detectors measured a width of the beam profile consitent with the expected one. The imaging property of each detector was then tested by inserting samples of different material and shape in the beam. All the samples were correctly reconstructed and the definition of the reconstruction depends on the type of readout anode. The fast neutron beam profile reconstruction was then compared to the one obtained by diamond detectors positioned on the same beamline while the thermal neutron one was compared to the imaged obtained by cadmium-coupled x-rays films. Also efficiency and the gamma background rejection have been determined. These prototypes represent the first step towards

An X-ray imager based on silicon microstrip detector and coded mask

International Nuclear Information System (INIS)

Del Monte, E.; Costa, E.; Di Persio, G.; Donnarumma, I.; Evangelista, Y.; Feroci, M.; Frutti, M.; Lapshov, I.; Lazzarotto, F.; Mastropietro, M.; Morelli, E.; Pacciani, L.; Porrovecchio, G.; Rapisarda, M.; Rubini, A.; Soffitta, P.; Tavani, M.; Argan, A.

2007-01-01

SuperAGILE is the X-ray monitor of AGILE, a satellite mission for gamma-ray astronomy, and it is the first X-ray imaging instrument based on the technology of the silicon microstrip detectors combined with a coded aperture imaging technique. The SuperAGILE detection plane is composed of four 1-D silicon microstrip detector modules, mechanically coupled to tungsten coded mask units. The detector strips are separately and individually connected to the input analogue channels of the front-end electronics, composed of low-noise and low-power consumption VLSI ASIC chips. SuperAGILE can produce 1-D images with 6 arcmin angular resolution and ∼2-3 arcmin localisation capability, for intense sources, in a field of view composed of two orthogonal areas of 107 deg. x 68 deg. The time resolution is 2 μs, the overall dead time is ∼5 μs and the electronic noise is ∼7.5 keV full-width at half-maximum. The resulting instrument is very compact (40x40x14 cm 3 ), light (10 kg) and has low power consumption (12 W). AGILE is a mission of the Agenzia Spaziale Italiana and its launch is planned in 2007 in a low equatorial Earth orbit. In this contribution we present SuperAGILE and discuss its performance and scientific objectives

GPU based Monte Carlo for PET image reconstruction: detector modeling

International Nuclear Information System (INIS)

Légrády; Cserkaszky, Á; Lantos, J.; Patay, G.; Bükki, T.

2011-01-01

Monte Carlo (MC) calculations and Graphical Processing Units (GPUs) are almost like the dedicated hardware designed for the specific task given the similarities between visible light transport and neutral particle trajectories. A GPU based MC gamma transport code has been developed for Positron Emission Tomography iterative image reconstruction calculating the projection from unknowns to data at each iteration step taking into account the full physics of the system. This paper describes the simplified scintillation detector modeling and its effect on convergence. (author)

A Low-Noise Direct Incremental A/D Converter for FET-Based THz Imaging Detectors

Directory of Open Access Journals (Sweden)

Moustafa Khatib

2018-06-01

Full Text Available This paper presents the design, implementation and characterization results of a pixel-level readout chain integrated with a FET-based terahertz (THz detector for imaging applications. The readout chain is fabricated in a standard 150-nm CMOS technology and contains a cascade of a preamplification and noise reduction stage based on a parametric chopper amplifier and a direct analog-to-digital conversion by means of an incremental ΣΔ converter, performing a lock-in operation with modulated sources. The FET detector is integrated with an on-chip antenna operating in the frequency range of 325–375 GHz and compliant with all process design rules. The cascade of the FET THz detector and readout chain is evaluated in terms of responsivity and Noise Equivalent Power (NEP measurements. The measured readout input-referred noise of 1.6 μ V r m s allows preserving the FET detector sensitivity by achieving a minimum NEP of 376 pW/ Hz in the optimum bias condition, while directly providing a digital output. The integrated readout chain features 65-dB peak-SNR and 80-μ W power consumption from a 1.8-V supply. The area of the antenna-coupled FET detector and the readout chain fits a pixel pitch of 455 μm, which is suitable for pixel array implementation. The proposed THz pixel has been successfully applied for imaging of concealed objects in a paper envelope under continuous-wave illumination.

Correction method and software for image distortion and nonuniform response in charge-coupled device-based x-ray detectors utilizing x-ray image intensifier

International Nuclear Information System (INIS)

Ito, Kazuki; Kamikubo, Hironari; Yagi, Naoto; Amemiya, Yoshiyuki

2005-01-01

An on-site method of correcting the image distortion and nonuniform response of a charge-coupled device (CCD)-based X-ray detector was developed using the response of the imaging plate as a reference. The CCD-based X-ray detector consists of a beryllium-windowed X-ray image intensifier (Be-XRII) and a CCD as the image sensor. An image distortion of 29% was improved to less than 1% after the correction. In the correction of nonuniform response due to image distortion, subpixel approximation was performed for the redistribution of pixel values. The optimal number of subpixels was also discussed. In an experiment with polystyrene (PS) latex, it was verified that the correction of both image distortion and nonuniform response worked properly. The correction for the 'contrast reduction' problem was also demonstrated for an isotropic X-ray scattering pattern from the PS latex. (author)

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.

Si and gaas pixel detectors for medical imaging applications

International Nuclear Information System (INIS)

Bisogni, M. G.

2001-01-01

As the use of digital radiographic equipment in the morphological imaging field is becoming the more and more diffuse, the research of new and more performing devices from public institutions and industrial companies is in constant progress. Most of these devices are based on solid-state detectors as X-ray sensors. Semiconductor pixel detectors, originally developed in the high energy physics environment, have been then proposed as digital detector for medical imaging applications. In this paper a digital single photon counting device, based on silicon and GaAs pixel detector, is presented. The detector is a thin slab of semiconductor crystal where an array of 64 by 64 square pixels, 170- m side, has been built on one side. The data read-out is performed by a VLSI integrated circuit named Photon Counting Chip (PCC), developed within the MEDIPIX collaboration. Each chip cell geometrically matches the sensor pixel. It contains a charge preamplifier, a threshold comparator and a 15 bits pseudo-random counter and it is coupled to the detector by means of bump bonding. Most important advantages of such system, with respect to a traditional X-rays film/screen device, are the wider linear dynamic range (3x104) and the higher performance in terms of MTF and DQE. Besides the single photon counting architecture allows to detect image contrasts lower than 3%. Electronics read-out performance as well as imaging capabilities of the digital device will be presented. Images of mammographic phantoms acquired with a standard Mammographic tube will be compared with radiographs obtained with traditional film/screen systems

Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Larsson, Jakob C., E-mail: jakob.larsson@biox.kth.se; Lundström, Ulf; Hertz, Hans M. [Biomedical and X-ray Physics, Department of Applied Physics, KTH Royal Institute of Technology/Albanova, Stockholm 10691 (Sweden)

2016-06-15

Purpose: High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. Methods: The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency and effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. Results: There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28–38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. Conclusions: The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.

High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

Science.gov (United States)

Abu Anas, Emran Mohammad; Kim, Jae Gon; Lee, Soo Yeol; Kamrul Hasan, Md

2011-10-01

The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

International Nuclear Information System (INIS)

Anas, Emran Mohammad Abu; Hasan, Md Kamrul; Kim, Jae Gon; Lee, Soo Yeol

2011-01-01

The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

The pin pixel detector--X-ray imaging

CERN Document Server

Bateman, J E; Derbyshire, G E; Duxbury, D M; Marsh, A S; Simmons, J E; Stephenson, R

2002-01-01

The development and testing of a soft X-ray gas pixel detector, which uses connector pins for the anodes is reported. Based on a commercial 100 pin connector block, a prototype detector of aperture 25.4 mm centre dot 25.4 mm can be economically fabricated. The individual pin anodes all show the expected characteristics of small gas detectors capable of counting rates reaching 1 MHz per pin. A 2-dimensional resistive divide readout system has been developed to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics.

X-ray imaging with the PILATUS 100k detector

DEFF Research Database (Denmark)

Bech, Martin; Bunk, O.; David, C.

2008-01-01

We report on the application of the PILATUS 100K pixel detector for medical imaging. Experimental results are presented in the form of X-ray radiographs using standard X-ray absorption contrast and a recently developed phase contrast imaging method. The results obtained with the PILATUS detector...... are compared to results obtained with a conventional X-ray imaging system consisting of an X-ray scintillation screen, lens optics, and a charge coupled device. Finally, the results for both systems are discussed more quantitatively based on an image power spectrum analysis. Udgivelsesdato: April...

Musculoskeletal imaging with a prototype photon-counting detector.

Science.gov (United States)

Gruber, M; Homolka, P; Chmeissani, M; Uffmann, M; Pretterklieber, M; Kainberger, F

2012-01-01

To test a digital imaging X-ray device based on the direct capture of X-ray photons with pixel detectors, which are coupled with photon-counting readout electronics. The chip consists of a matrix of 256 × 256 pixels with a pixel pitch of 55 μm. A monolithic image of 11.2 cm × 7 cm was obtained by the consecutive displacement approach. Images of embalmed anatomical specimens of eight human hands were obtained at four different dose levels (skin dose 2.4, 6, 12, 25 μGy) with the new detector, as well as with a flat-panel detector. The overall rating scores for the evaluated anatomical regions ranged from 5.23 at the lowest dose level, 6.32 at approximately 6 μGy, 6.70 at 12 μGy, to 6.99 at the highest dose level with the photon-counting system. The corresponding rating scores for the flat-panel detector were 3.84, 5.39, 6.64, and 7.34. When images obtained at the same dose were compared, the new system outperformed the conventional DR system at the two lowest dose levels. At the higher dose levels, there were no significant differences between the two systems. The photon-counting detector has great potential to obtain musculoskeletal images of excellent quality at very low dose levels.

Improvement of an X-ray imaging detector based on a scintillating guides screen

CERN Document Server

Badel, X; Linnros, J; Kleimann, P; Froejdh, C; Petersson, C S

2002-01-01

An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achie...

CCD-based vertex detectors

CERN Document Server

Damerell, C J S

2005-01-01

Over the past 20 years, CCD-based vertex detectors have been used to construct some of the most precise 'tracking microscopes' in particle physics. They were initially used by the ACCMOR collaboration for fixed target experiments in CERN, where they enabled the lifetimes of some of the shortest-lived charm particles to be measured precisely. The migration to collider experiments was accomplished in the SLD experiment, where the original 120 Mpixel detector was later upgraded to one with 307 Mpixels. This detector was used in a range of physics studies which exceeded the capability of the LEP detectors, including the most precise limit to date on the Bs mixing parameter. This success, and the high background hit densities that will inevitably be encountered at the future TeV-scale linear collider, have established the need for a silicon pixel-based vertex detector at this machine. The technical options have now been broadened to include a wide range of possible silicon imaging technologies as well as CCDs (mon...

Solid-state, flat-panel, digital radiography detectors and their physical imaging characteristics

Energy Technology Data Exchange (ETDEWEB)

Cowen, A.R. [LXi Research, Academic Unit of Medical Physics, University of Leeds, West Yorkshire (United Kingdom)], E-mail: a.r.cowen@leeds.ac.uk; Kengyelics, S.M.; Davies, A.G. [LXi Research, Academic Unit of Medical Physics, University of Leeds, West Yorkshire (United Kingdom)

2008-05-15

Solid-state, digital radiography (DR) detectors, designed specifically for standard projection radiography, emerged just before the turn of the millennium. This new generation of digital image detector comprises a thin layer of x-ray absorptive material combined with an electronic active matrix array fabricated in a thin film of hydrogenated amorphous silicon (a-Si:H). DR detectors can offer both efficient (low-dose) x-ray image acquisition plus on-line readout of the latent image as electronic data. To date, solid-state, flat-panel, DR detectors have come in two principal designs, the indirect-conversion (x-ray scintillator-based) and the direct-conversion (x-ray photoconductor-based) types. This review describes the underlying principles and enabling technologies exploited by these designs of detector, and evaluates their physical imaging characteristics, comparing performance both against each other and computed radiography (CR). In standard projection radiography indirect conversion DR detectors currently offer superior physical image quality and dose efficiency compared with direct conversion DR and modern point-scan CR. These conclusions have been confirmed in the findings of clinical evaluations of DR detectors. Future trends in solid-state DR detector technologies are also briefly considered. Salient innovations include WiFi-enabled, portable DR detectors, improvements in x-ray absorber layers and developments in alternative electronic media to a-Si:H.

The design and imaging characteristics of dynamic, solid-state, flat-panel x-ray image detectors for digital fluoroscopy and fluorography

International Nuclear Information System (INIS)

Cowen, A.R.; Davies, A.G.; Sivananthan, M.U.

2008-01-01

Dynamic, flat-panel, solid-state, x-ray image detectors for use in digital fluoroscopy and fluorography emerged at the turn of the millennium. This new generation of dynamic detectors utilize a thin layer of x-ray absorptive material superimposed upon an electronic active matrix array fabricated in a film of hydrogenated amorphous silicon (a-Si:H). Dynamic solid-state detectors come in two basic designs, the indirect-conversion (x-ray scintillator based) and the direct-conversion (x-ray photoconductor based). This review explains the underlying principles and enabling technologies associated with these detector designs, and evaluates their physical imaging characteristics, comparing their performance against the long established x-ray image intensifier television (TV) system. Solid-state detectors afford a number of physical imaging benefits compared with the latter. These include zero geometrical distortion and vignetting, immunity from blooming at exposure highlights and negligible contrast loss (due to internal scatter). They also exhibit a wider dynamic range and maintain higher spatial resolution when imaging over larger fields of view. The detective quantum efficiency of indirect-conversion, dynamic, solid-state detectors is superior to that of both x-ray image intensifier TV systems and direct-conversion detectors. Dynamic solid-state detectors are playing a burgeoning role in fluoroscopy-guided diagnosis and intervention, leading to the displacement of x-ray image intensifier TV-based systems. Future trends in dynamic, solid-state, digital fluoroscopy detectors are also briefly considered. These include the growth in associated three-dimensional (3D) visualization techniques and potential improvements in dynamic detector design

Ghost imaging with a single detector

International Nuclear Information System (INIS)

Bromberg, Yaron; Katz, Ori; Silberberg, Yaron

2009-01-01

We experimentally demonstrate pseudothermal ghost imaging and ghost diffraction using only a single detector. We achieve this by replacing the high-resolution detector of the reference beam with a computation of the propagating field, following a recent proposal by Shapiro [Phys. Rev. A 78, 061802(R) (2008)]. Since only a single detector is used, this provides experimental evidence that pseudothermal ghost imaging does not rely on nonlocal quantum correlations. In addition, we show the depth-resolving capability of this ghost imaging technique.

Soucreless efficiency calibration for HPGe detector based on medical images

International Nuclear Information System (INIS)

Chen Chaobin; She Ruogu; Xiao Gang; Zuo Li

2012-01-01

Digital phantom of patient and region of interest (supposed to be filled with isotropy volume source) are built from medical CT images. They are used to calculate the detection efficiency of HPGe detectors located outside of human body by sourceless calibration method based on a fast integral technique and MCNP code respectively, and the results from two codes are in good accord besides a max difference about 5% at intermediate energy region. The software produced in this work are in better behavior than Monte Carlo code not only in time consume but also in complexity of problem to solve. (authors)

Autoradiography Imaging in Targeted Alpha Therapy with Timepix Detector

Directory of Open Access Journals (Sweden)

Ruqaya AL Darwish

2015-01-01

Full Text Available There is a lack of data related to activity uptake and particle track distribution in targeted alpha therapy. These data are required to estimate the absorbed dose on a cellular level as alpha particles have a limited range and traverse only a few cells. Tracking of individual alpha particles is possible using the Timepix semiconductor radiation detector. We investigated the feasibility of imaging alpha particle emissions in tumour sections from mice treated with Thorium-227 (using APOMAB, with and without prior chemotherapy and Timepix detector. Additionally, the sensitivity of the Timepix detector to monitor variations in tumour uptake based on the necrotic tissue volume was also studied. Compartmental analysis model was used, based on the obtained imaging data, to assess the Th-227 uptake. Results show that alpha particle, photon, electron, and muon tracks were detected and resolved by Timepix detector. The current study demonstrated that individual alpha particle emissions, resulting from targeted alpha therapy, can be visualised and quantified using Timepix detector. Furthermore, the variations in the uptake based on the tumour necrotic volume have been observed with four times higher uptake for tumours pretreated with chemotherapy than for those without chemotherapy.

A gas pixel detector for X-ray imaging

International Nuclear Information System (INIS)

Bateman, J.E.; Connolly, J.F.

1991-11-01

A simple, robust form of gas pixel detector is discussed which is based on the use of electronic connector pins as the gain elements. With a rate capability of >10 5 counts/s per pin, an X-ray imaging detector system capable of counting at global rates of the order of 10 10 counts/s is foreseen. (author)

Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging.

Science.gov (United States)

Iwanczyk, Jan S; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C; Hartsough, Neal E; Malakhov, Nail; Wessel, Jan C

2009-01-01

The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm(2)/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a (57)Co source. An output rate of 6×10(6) counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and

A DBN based anomaly targets detector for HSI

Science.gov (United States)

Ma, Ning; Wang, Shaojun; Yu, Jinxiang; Peng, Yu

2017-10-01

Due to the assumption that Hyperspectral image (HSI) should conform to Gaussian distribution, traditional Mahalanobis distance-based anomaly targets detectors perform poor because the assumption may not always hold. In order to solve those problems, a deep learning based detector, Deep Belief Network(DBN) anomaly detector(DBN-AD), was proposed to fit the unknown distribution of HSI by energy modeling, the reconstruction errors of this encode-decode processing are used for discriminating the anomaly targets. Experiments are implemented on real and synthesized HSI dataset which collection by Airborne Visible Infra-Red Imaging Spectrometer (AVIRIS). Comparing to classic anomaly detector, the proposed method shows better performance, it performs about 0.17 higher in Area Under ROC Curve (AUC) than that of Reed-Xiaoli detector(RXD) and Kernel-RXD (K-RXD).

Automatic analysis of quality of images from X-ray digital flat detectors

International Nuclear Information System (INIS)

Le Meur, Y.

2009-04-01

Since last decade, medical imaging has grown up with the development of new digital imaging techniques. In the field of X-ray radiography, new detectors replace progressively older techniques, based on film or x-ray intensifiers. These digital detectors offer a higher sensibility and reduced overall dimensions. This work has been prepared with Trixell, the world leading company in flat detectors for medical radiography. It deals with quality control on digital images stemming from these detectors. High quality standards of medical imaging impose a close analysis of the defects that can appear on the images. This work describes a complete process for quality analysis of such images. A particular focus is given on the detection task of the defects, thanks to methods well adapted to our context of spatially correlated defects in noise background. (author)

DIRC, the internally reflecting ring imaging Cherenkov detector for BABAR

International Nuclear Information System (INIS)

Adam, I.; Aston, D.

1997-11-01

The DIRC is a new type of Cherenkov imaging device that will be used for the first time in the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiator and light guide. The principles of the DIRC ring imaging Cherenkov technique are explained and results from the prototype program are presented. Its choice for the BABAR detector particle identification system is motivated, followed by a discussion of the quartz radiator properties and the detector design

Objective image characterization of a spectral CT scanner with dual-layer detector

Science.gov (United States)

Ozguner, Orhan; Dhanantwari, Amar; Halliburton, Sandra; Wen, Gezheng; Utrup, Steven; Jordan, David

2018-01-01

This work evaluated the performance of a detector-based spectral CT system by obtaining objective reference data, evaluating attenuation response of iodine and accuracy of iodine quantification, and comparing conventional CT and virtual monoenergetic images in three common phantoms. Scanning was performed using the hospital’s clinical adult body protocol. Modulation transfer function (MTF) was calculated for a tungsten wire and visual line pair targets were evaluated. Image noise power spectrum (NPS) and pixel standard deviation were calculated. MTF for monoenergetic images agreed with conventional images within 0.05 lp cm-1. NPS curves indicated that noise texture of 70 keV monoenergetic images is similar to conventional images. Standard deviation measurements showed monoenergetic images have lower noise except at 40 keV. Mean CT number and CNR agreed with conventional images at 75 keV. Measured iodine concentration agreed with true concentration within 6% for inserts at the center of the phantom. Performance of monoenergetic images at detector based spectral CT is the same as, or better than, that of conventional images. Spectral acquisition and reconstruction with a detector based platform represents the physical behaviour of iodine as expected and accurately quantifies the material concentration.

Space situational awareness satellites and ground based radiation counting and imaging detector technology

International Nuclear Information System (INIS)

Jansen, Frank; Behrens, Joerg; Pospisil, Stanislav; Kudela, Karel

2011-01-01

We review the current status from the scientific and technological point of view of solar energetic particles, solar and galactic cosmic ray measurements as well as high energy UV-, X- and gamma-ray imaging of the Sun. These particles and electromagnetic data are an important tool for space situational awareness (SSA) aspects like space weather storm predictions to avoid failures in space, air and ground based technological systems. Real time data acquisition, position and energy sensitive imaging are demanded by the international space weather forecast services. We present how newly developed, highly miniaturized radiation detectors can find application in space in view of future SSA related satellites as a novel space application due to their counting and imaging capabilities.

Space situational awareness satellites and ground based radiation counting and imaging detector technology

Energy Technology Data Exchange (ETDEWEB)

Jansen, Frank, E-mail: frank.jansen@dlr.de [DLR Institute of Space Systems, Robert-Hooke-Str. 7, 28359 Bremen (Germany); Behrens, Joerg [DLR Institute of Space Systems, Robert-Hooke-Str. 7, 28359 Bremen (Germany); Pospisil, Stanislav [Czech Technical University, IEAP, 12800 Prague 2, Horska 3a/22 (Czech Republic); Kudela, Karel [Slovak Academy of Sciences, IEP, 04001 Kosice, Watsonova 47 (Slovakia)

2011-05-15

We review the current status from the scientific and technological point of view of solar energetic particles, solar and galactic cosmic ray measurements as well as high energy UV-, X- and gamma-ray imaging of the Sun. These particles and electromagnetic data are an important tool for space situational awareness (SSA) aspects like space weather storm predictions to avoid failures in space, air and ground based technological systems. Real time data acquisition, position and energy sensitive imaging are demanded by the international space weather forecast services. We present how newly developed, highly miniaturized radiation detectors can find application in space in view of future SSA related satellites as a novel space application due to their counting and imaging capabilities.

Workshops on radiation imaging detectors

International Nuclear Information System (INIS)

Sochinskii, N.V.; Sun, G.C.; Kostamo, P.; Silenas, A.; Saynatjoki, A.; Grant, J.; Owens, A.; Kozorezov, A.G.; Noschis, E.; Van Eijk, C.; Nagarkar, V.; Sekiya, H.; Pribat, D.; Campbell, M.; Lundgren, J.; Arques, M.; Gabrielli, A.; Padmore, H.; Maiorino, M.; Volpert, M.; Lebrun, F.; Van der Putten, S.; Pickford, A.; Barnsley, R.; Anton, M.E.G.; Mitschke, M.; Gros d'Aillon, E.; Frojdh, C.; Norlin, B.; Marchal, J.; Quattrocchi, M.; Stohr, U.; Bethke, K.; Bronnimann, C.H.; Pouvesle, J.M.; Hoheisel, M.; Clemens, J.C.; Gallin-Martel, M.L.; Bergamaschi, A.; Redondo-Fernandez, I.; Gal, O.; Kwiatowski, K.; Montesi, M.C.; Smith, K.

2005-01-01

This document gathers the transparencies that were presented at the international workshop on radiation imaging detectors. 9 sessions were organized: 1) materials for detectors and detector structure, 2) front end electronics, 3) interconnected technologies, 4) space, fusion applications, 5) the physics of detection, 6) industrial applications, 7) synchrotron radiation, 8) X-ray sources, and 9) medical and other applications

Workshops on radiation imaging detectors

Energy Technology Data Exchange (ETDEWEB)

Sochinskii, N V; Sun, G C; Kostamo, P; Silenas, A; Saynatjoki, A; Grant, J; Owens, A; Kozorezov, A G; Noschis, E; Van Eijk, C; Nagarkar, V; Sekiya, H; Pribat, D; Campbell, M; Lundgren, J; Arques, M; Gabrielli, A; Padmore, H; Maiorino, M; Volpert, M; Lebrun, F; Van der Putten, S; Pickford, A; Barnsley, R; Anton, M E.G.; Mitschke, M; Gros d' Aillon, E; Frojdh, C; Norlin, B; Marchal, J; Quattrocchi, M; Stohr, U; Bethke, K; Bronnimann, C H; Pouvesle, J M; Hoheisel, M; Clemens, J C; Gallin-Martel, M L; Bergamaschi, A; Redondo-Fernandez, I; Gal, O; Kwiatowski, K; Montesi, M C; Smith, K

2005-07-01

This document gathers the transparencies that were presented at the international workshop on radiation imaging detectors. 9 sessions were organized: 1) materials for detectors and detector structure, 2) front end electronics, 3) interconnected technologies, 4) space, fusion applications, 5) the physics of detection, 6) industrial applications, 7) synchrotron radiation, 8) X-ray sources, and 9) medical and other applications.

Pixel Detectors for Particle Physics and Imaging Applications

CERN Document Server

Wermes, N

2003-01-01

Semiconductor pixel detectors offer features for the detection of radiation which are interesting for particle physics detectors as well as for imaging e.g. in biomedical applications (radiography, autoradiography, protein crystallography) or in Xray astronomy. At the present time hybrid pixel detectors are technologically mastered to a large extent and large scale particle detectors are being built. Although the physical requirements are often quite different, imaging applications are emerging and interesting prototype results are available. Monolithic detectors, however, offer interesting features for both fields in future applications. The state of development of hybrid and monolithic pixel detectors, excluding CCDs, and their different suitability for particle detection and imaging, is reviewed.

CFAR Edge Detector for Polarimetric SAR Images

DEFF Research Database (Denmark)

Schou, Jesper; Skriver, Henning; Nielsen, Allan Aasbjerg

2003-01-01

Finding the edges between different regions in an image is one of the fundamental steps of image analysis, and several edge detectors suitable for the special statistics of synthetic aperture radar (SAR) intensity images have previously been developed. In this paper, a new edge detector for polar...

A direct reflection OLVF debris detector based on dark-field imaging

Science.gov (United States)

Li, Bo; Xi, Yinhu; Feng, Song; Mao, Junhong; Xie, You-Bai

2018-06-01

To solve the problems of monitoring wear debris in black oil, a direct reflection online visual ferrograph (OLVF) debris detector is presented. In current OLVF detectors, a reflected light source is used. The emitted light is reflected by wear debris directly instead of passing through the lube oil. Therefore, the transparency of the lube oil ceases to matter. Two experiments were conducted to validate the wear debris imaging feasibility and effectiveness of the newly developed detector. The results show that the visual feature information of the wear debris can be reliably obtained from black oil by this detector, and it can also be used to track the fast-changing wear of tribopairs at different wear stages. To the best of our knowledge, to date there is no other report for solving this issue.

Recent developments in X-ray imaging detectors

CERN Document Server

Moy, J P

2000-01-01

The replacement of the radiographic film in medical imaging has been the driving force in X-ray imaging developments. It requires a approx 40 cm wide detector to cover all examinations, an equivalent noise level of 1-5 X-ray quanta per pixel, and spatial resolution in the range 100-150 mu m. The need for entirely electronic imaging equipments has fostered the development of many X-ray detectors, most of them based on an array of amorphous silicon pixels, which is the only technology capable to achieve such large areas. Essentially, two concepts have been implemented: - intermediate conversion of X-rays to light by a scintillator, detected by an array of light sensitive pixels, comprising a photodiode and a switching device, either a TFT or a diode. - conversion into electron-hole pairs in a photoconductor, collected by an array of electrodes and switches. In both cases, charge amplifiers read the generated charges line by line. Scintillator and photoconductor-based systems are now close to production. They ac...

Evaluation of imaging quality for flat-panel detector based low dose C-arm CT system

International Nuclear Information System (INIS)

Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Sungchae; Huh, Young

2015-01-01

The image quality associated with the extent of the angle of gantry rotation, the number of projection views, and the dose of X-ray radiation was investigated in flat-panel detector (FPD) based C-arm cone-beam computed tomography (CBCT) system for medical applications. A prototype CBCT system for the projection acquisition used the X-ray tube (A-132, Varian inc.) having rhenium-tungsten molybdenum target and flat panel a-Si X-ray detector (PaxScan 4030CB, Varian inc.) having a 397 x 298 mm active area with 388 μm pixel pitch and 1024 x 768 pixels in 2 by 2 binning mode. The performance comparison of X-ray imaging quality was carried out using the Feldkamp, Davis, and Kress (FDK) reconstruction algorithm between different conditions of projection acquisition. In this work, head-and-dental (75 kVp/20 mA) and chest (90 kVp/25 mA) phantoms were used to evaluate the image quality. The 361 (30 fps x 12 s) projection data during 360 deg. gantry rotation with 1 deg. interval for the 3D reconstruction were acquired. Parke weighting function were applied to handle redundant data and improve the reconstructed image quality in a mobile C-arm system with limited rotation angles. The reconstructed 3D images were investigated for comparison of qualitative image quality in terms of scan protocols (projection views, rotation angles and exposure dose). Furthermore, the performance evaluation in image quality will be investigated regarding X-ray dose and limited projection data for a FPD based mobile C-arm CBCT system. (authors)

MPGD-based counters of single photons developed for COMPASS RICH-1

Czech Academy of Sciences Publication Activity Database

Alexeev, M.; Birsa, R.; Bodlak, M.; Bradamante, F.; Bressan, A.; Büchele, M.; Chiosso, M.; Ciliberti, P.; Dalla Torre, S.; Dasgupta, S.; Denisov, O.; Duic, V.; Finger, M.; Finger jr., M.; Fischer, H.; Giorgi, M.; Gobbo, B.; Gregori, M.; Herrmann, F.; Königsmann, K.; Levorato, S.; Maggiora, A.; Martin, A.; Menon, G.; Nováková, Kateřina; Nový, J.; Panzieri, D.; Pereira, F.A.; Santos, C.A.; Sbrizzai, G.; Schiavon, P.; Schorb, S.; Slunečka, M.; Sozzi, F.; Steiger, Lukáš; Sulc, M.; Tessarotto, F.; Veloso, J.F.C.A.

2014-01-01

Roč. 9, č. 9 (2014), C09017-C09017 ISSN 1748-0221. [International Conference on Instrumentation for Colliding Beam Physics. Budker Inst Nucl Phys, Novosibirsk, 24.02.2014-01.03.2014] Institutional support: RVO:61389021 Keywords : Hybrid detectors * Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc) * Electron multipliers (gas) * visible and IR photons (gas) (gas-photocathodes, solid-photocathodes) * Photon detectors for UV Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.399, year: 2014 http://iopscience.iop.org/1748-0221/9/09/C09017/pdf/1748-0221_9_09_C09017.pdf

Fast-neutron and gamma-ray imaging with a capillary liquid xenon converter coupled to a gaseous photomultiplier

Science.gov (United States)

Israelashvili, I.; Coimbra, A. E. C.; Vartsky, D.; Arazi, L.; Shchemelinin, S.; Caspi, E. N.; Breskin, A.

2017-09-01

Gamma-ray and fast-neutron imaging was performed with a novel liquid xenon (LXe) scintillation detector read out by a Gaseous Photomultiplier (GPM). The 100 mm diameter detector prototype comprised a capillary-filled LXe converter/scintillator, coupled to a triple-THGEM imaging-GPM, with its first electrode coated by a CsI UV-photocathode, operated in Ne/5%CH4 at cryogenic temperatures. Radiation localization in 2D was derived from scintillation-induced photoelectron avalanches, measured on the GPM's segmented anode. The localization properties of 60Co gamma-rays and a mixed fast-neutron/gamma-ray field from an AmBe neutron source were derived from irradiation of a Pb edge absorber. Spatial resolutions of 12± 2 mm and 10± 2 mm (FWHM) were reached with 60Co and AmBe sources, respectively. The experimental results are in good agreement with GEANT4 simulations. The calculated ultimate expected resolutions for our application-relevant 4.4 and 15.1 MeV gamma-rays and 1-15 MeV neutrons are 2-4 mm and ~ 2 mm (FWHM), respectively. These results indicate the potential applicability of the new detector concept to Fast-Neutron Resonance Radiography (FNRR) and Dual-Discrete-Energy Gamma Radiography (DDEGR) of large objects.

A GaAs pixel detectors-based digital mammographic system: Performances and imaging tests results

International Nuclear Information System (INIS)

Annovazzi, A.; Amendolia, S.R.; Bigongiari, A.; Bisogni, M.G.; Catarsi, F.; Cesqui, F.; Cetronio, A.; Colombo, F.; Delogu, P.; Fantacci, M.E.; Gilberti, A.; Lanzieri, C.; Lavagna, S.; Novelli, M.; Passuello, G.; Paternoster, G.; Pieracci, M.; Poletti, M.; Quattrocchi, M.; Rosso, V.; Stefanini, A.; Testa, A.; Venturelli, L.

2007-01-01

The prototype presented in this paper is based on GaAs pixel detectors read-out by the PCC/MEDIPIX I circuit. The active area of a sensor is about 1 cm 2 therefore to cover the typical irradiation field used in mammography (18x24 cm 2 ), 18 GaAs detection units have been organized in two staggered rows of nine chips each and moved by a stepper motor in the orthogonal direction. The system is integrated in a mammographic equipment which comprehends the X-ray tube, the bias and data acquisition systems and the PC-based control system. The prototype has been developed in the framework of the Integrated Mammographic Imaging (IMI) project, an industrial research activity aiming to develop innovative instrumentation for morphologic and functional imaging. The project has been supported by the Italian Ministry of Education, University and Research (MIUR) and by five Italian High Tech companies, Alenia Marconi Systems (AMS), CAEN, Gilardoni, LABEN and Poli.Hi.Tech., in collaboration with the universities of Ferrara, Roma 'La Sapienza', Pisa and the Istituto Nazionale di Fisica Nucleare (INFN). In this paper, we report on the electrical characterization and the first imaging test results of the digital mammographic system. To assess the imaging capability of such a detector we have built a phantom, which simulates the breast tissue with malignancies. The radiographs of the phantom, obtained by delivering an entrance dose of 4.8 mGy, have shown particulars with a measured contrast below 1%

A GaAs pixel detectors-based digital mammographic system: Performances and imaging tests results

Science.gov (United States)

Annovazzi, A.; Amendolia, S. R.; Bigongiari, A.; Bisogni, M. G.; Catarsi, F.; Cesqui, F.; Cetronio, A.; Colombo, F.; Delogu, P.; Fantacci, M. E.; Gilberti, A.; Lanzieri, C.; Lavagna, S.; Novelli, M.; Passuello, G.; Paternoster, G.; Pieracci, M.; Poletti, M.; Quattrocchi, M.; Rosso, V.; Stefanini, A.; Testa, A.; Venturelli, L.

2007-06-01

The prototype presented in this paper is based on GaAs pixel detectors read-out by the PCC/MEDIPIX I circuit. The active area of a sensor is about 1 cm 2 therefore to cover the typical irradiation field used in mammography (18×24 cm 2), 18 GaAs detection units have been organized in two staggered rows of nine chips each and moved by a stepper motor in the orthogonal direction. The system is integrated in a mammographic equipment which comprehends the X-ray tube, the bias and data acquisition systems and the PC-based control system. The prototype has been developed in the framework of the Integrated Mammographic Imaging (IMI) project, an industrial research activity aiming to develop innovative instrumentation for morphologic and functional imaging. The project has been supported by the Italian Ministry of Education, University and Research (MIUR) and by five Italian High Tech companies, Alenia Marconi Systems (AMS), CAEN, Gilardoni, LABEN and Poli.Hi.Tech., in collaboration with the universities of Ferrara, Roma "La Sapienza", Pisa and the Istituto Nazionale di Fisica Nucleare (INFN). In this paper, we report on the electrical characterization and the first imaging test results of the digital mammographic system. To assess the imaging capability of such a detector we have built a phantom, which simulates the breast tissue with malignancies. The radiographs of the phantom, obtained by delivering an entrance dose of 4.8 mGy, have shown particulars with a measured contrast below 1%.

Recent Developments in GEM-Based Neutron Detectors

International Nuclear Information System (INIS)

Saenboonruang, K.

2014-01-01

The gas electron multiplier (GEM) detector is a relatively new gaseous detector that has been used for less than 20 years. Since the discovery in 1997 by F. Sauli, the GEM detector has shown excellent properties including high rate capability, excellent resolutions, low discharge probability, and excellent radiation hardness. These promising properties have led the GEM detector to gain popularity and attention amongst physicists and researchers. In particular, the GEM detector can also be modified to be used as a neutron detector by adding appropriate neutron converters. With properties stated above and the need to replace the expensive 3 He-based neutron detectors, the GEM-based neutron detector will be one of the most powerful and affordable neutron detectors. Applications of the GEM-based neutron detectors vary from researches in nuclear and particle physics, neutron imaging, and national security. Although several promising progresses and results have been shown and published in the past few years, further improvement is still needed in order to improve the low neutron detection efficiency (only a few percent) and to widen the possibilities for other uses.

A digital X-ray imaging system based on silicon strip detectors working in edge-on configuration

Energy Technology Data Exchange (ETDEWEB)

Bolanos, L. [CEADEN, Calle 30 502 e/ 5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Boscardin, M. [IRST, Fondazione Bruno Kessler, Via Sommarive 18, Povo, 38100 Trento (Italy); Cabal, A.E. [CEADEN, Calle 30 502 e/ 5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Diaz, M. [InSTEC, Ave. Salvador Allende esq. Luaces, Quinta de los Molinos, Ciudad Habana (Cuba); Grybos, P.; Maj, P. [Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Prino, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via P. Giuria 1, 10125 Torino (Italy); Ramello, L. [Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale, Via T. Michel 11, 15100 Alessandria (Italy)], E-mail: luciano.ramello@mfn.unipmn.it; Szczygiel, R. [Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland)

2009-09-21

We present the energy resolution and imaging performance of a digital X-ray imaging system based on a 512-strip silicon strip detector (SSD) working in the edge-on configuration. The SSDs tested in the system are 300 {mu}m thick with 1 or 2-cm-long strips and 100 {mu}m pitch. To ensure a very small dead area of the SSD working in edge-on configuration, the detector is cut perpendicular to the strips at a distance of only 20 {mu}m from the end of the strips. The 512-strip silicon detector is read out by eight 64-channel integrated circuits called DEDIX [Grybos et al., IEEE Trans. Nucl. Sci. NS-54 (2007) 1207]. The DEDIX IC operates in a single photon counting mode with two independent amplitude discriminators per channel. The readout electronic channel connected to a detector with effective input capacitance of about 2 pF has an average equivalent noise charge (ENC) of about 163 el. rms and is able to count 1 Mcps of average rate of input pulses. The system consisting of 512 channels has an excellent channel-to-channel uniformity-the effective threshold spread calculated to the charge-sensitive amplifier inputs is 12 el. rms (at one sigma level). With this system a few test images of a phantom have been taken in the 10-30 keV energy range.

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-05-18

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

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

International Nuclear Information System (INIS)

Shao, Yiping; Sun, Xishan; Lou, Kai

2015-01-01

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

Imaging performance of a Timepix detector based on semi-insulating GaAs

Science.gov (United States)

Zaťko, B.; Zápražný, Z.; Jakůbek, J.; Šagátová, A.; Boháček, P.; Sekáčová, M.; Korytár, D.; Nečas, V.; Žemlička, J.; Mora, Y.; Pichotka, M.

2018-01-01

This work focused on a Timepix chip [1] coupled with a bulk semi-insulating GaAs sensor. The sensor consisted of a matrix of 256 × 256 pixels with a pitch of 55 μm bump-bonded to a Timepix ASIC. The sensor was processed on a 350 μm-thick SI GaAs wafer. We carried out detector adjustment to optimize its performance. This included threshold equalization with setting up parameters of the Timepix chip, such as Ikrum, Pream, Vfbk, and so on. The energy calibration of the GaAs Timepix detector was realized using a 241Am radioisotope in two Timepix detector modes: time-over-threshold and threshold scan. An energy resolution of 4.4 keV in FWHM (Full Width at Half Maximum) was observed for 59.5 keV γ-photons using threshold scan mode. The X-ray imaging quality of the GaAs Timepix detector was tested using various samples irradiated by an X-ray source with a focal spot size smaller than 8 μm and accelerating voltage up to 80 kV. A 700 μm × 700 μm gold testing object (X-500-200-16Au with Siemens star) fabricated with high precision was used for the spatial resolution testing at different values of X-ray image magnification (up to 45). The measured spatial resolution of our X-ray imaging system was about 4 μm.

Review on the characteristics of radiation detectors for dosimetry and imaging

International Nuclear Information System (INIS)

Seco, Joao; Clasie, Ben; Partridge, Mike

2014-01-01

The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general

Feature Detector and Descriptor for Medical Images

Science.gov (United States)

Sargent, Dusty; Chen, Chao-I.; Tsai, Chang-Ming; Wang, Yuan-Fang; Koppel, Daniel

2009-02-01

The ability to detect and match features across multiple views of a scene is a crucial first step in many computer vision algorithms for dynamic scene analysis. State-of-the-art methods such as SIFT and SURF perform successfully when applied to typical images taken by a digital camera or camcorder. However, these methods often fail to generate an acceptable number of features when applied to medical images, because such images usually contain large homogeneous regions with little color and intensity variation. As a result, tasks like image registration and 3D structure recovery become difficult or impossible in the medical domain. This paper presents a scale, rotation and color/illumination invariant feature detector and descriptor for medical applications. The method incorporates elements of SIFT and SURF while optimizing their performance on medical data. Based on experiments with various types of medical images, we combined, adjusted, and built on methods and parameter settings employed in both algorithms. An approximate Hessian based detector is used to locate scale invariant keypoints and a dominant orientation is assigned to each keypoint using a gradient orientation histogram, providing rotation invariance. Finally, keypoints are described with an orientation-normalized distribution of gradient responses at the assigned scale, and the feature vector is normalized for contrast invariance. Experiments show that the algorithm detects and matches far more features than SIFT and SURF on medical images, with similar error levels.

A GaAs pixel detectors-based digital mammographic system: Performances and imaging tests results

Energy Technology Data Exchange (ETDEWEB)

Annovazzi, A. [LABEN S.p.A., Vimodrone-Milan (Italy); Amendolia, S.R. [Str. Dip. di Matematica e Fisica dell' Universita, Sassari and Sezione I.N.F.N., Pisa (Italy); Bigongiari, A. [CAEN S.p.A., Viareggio-Lucca (Italy); Bisogni, M.G. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Catarsi, F. [CAEN S.p.A., Viareggio-Lucca (Italy); Cesqui, F. [AMS S.p.A, Rome (Italy); Cetronio, A. [AMS S.p.A, Rome (Italy); Colombo, F. [LABEN S.p.A., Vimodrone-Milan (Italy); Delogu, P. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Fantacci, M.E. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Gilberti, A. [LABEN S.p.A., Vimodrone-Milan (Italy); Lanzieri, C. [AMS S.p.A, Rome (Italy); Lavagna, S. [AMS S.p.A, Rome (Italy); Novelli, M. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Passuello, G. [CAEN S.p.A., Viareggio-Lucca (Italy); Paternoster, G. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Pieracci, M. [CAEN S.p.A., Viareggio-Lucca (Italy); Poletti, M. [LABEN S.p.A., Vimodrone-Milan (Italy); Quattrocchi, M. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Rosso, V. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy); Stefanini, A. [Dipartimento di Fisica ' E. Fermi' dell' Universita and Sezione I.N.F.N., Pisa (Italy)]. E-mail: arnaldo.stefanini@pi.infn.it; Testa, A. [CAEN S.p.A., Viareggio-Lucca (Italy); Venturelli, L. [AMS S.p.A, Rome (Italy)

2007-06-11

The prototype presented in this paper is based on GaAs pixel detectors read-out by the PCC/MEDIPIX I circuit. The active area of a sensor is about 1 cm{sup 2} therefore to cover the typical irradiation field used in mammography (18x24 cm{sup 2}), 18 GaAs detection units have been organized in two staggered rows of nine chips each and moved by a stepper motor in the orthogonal direction. The system is integrated in a mammographic equipment which comprehends the X-ray tube, the bias and data acquisition systems and the PC-based control system. The prototype has been developed in the framework of the Integrated Mammographic Imaging (IMI) project, an industrial research activity aiming to develop innovative instrumentation for morphologic and functional imaging. The project has been supported by the Italian Ministry of Education, University and Research (MIUR) and by five Italian High Tech companies, Alenia Marconi Systems (AMS), CAEN, Gilardoni, LABEN and Poli.Hi.Tech., in collaboration with the universities of Ferrara, Roma 'La Sapienza', Pisa and the Istituto Nazionale di Fisica Nucleare (INFN). In this paper, we report on the electrical characterization and the first imaging test results of the digital mammographic system. To assess the imaging capability of such a detector we have built a phantom, which simulates the breast tissue with malignancies. The radiographs of the phantom, obtained by delivering an entrance dose of 4.8 mGy, have shown particulars with a measured contrast below 1%.

CCD-based X-ray detectors for X-ray diffraction studies

International Nuclear Information System (INIS)

Ito, K.; Amemiya, Y.

1999-01-01

CCD-based X-ray detectors are getting to be used for X-ray diffraction studies especially in the studies where real time (automated) measurements and time-resolved measurements are required. Principles and designs of two typical types of CCD-based detectors are described; one is ths system in which x-ray image intensifiers are coupled to maximize the detective quantum efficiency for time-resolved measurements, and the other is the system in which tapered optical fibers are coupled for the reduction of the image into the CCD, which is optimized for automated measurements for protein crystallography. These CCD-based X-ray detectors have an image distortion and non-uniformity of response to be corrected by software. Correction schemes which we have developed are also described. (author)

Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a muon tomography station based on GEM detectors

Energy Technology Data Exchange (ETDEWEB)

Gnanvo, Kondo, E-mail: kgnanvo@fit.edu [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Grasso, Leonard V.; Hohlmann, Marcus; Locke, Judson B.; Quintero, Amilkar [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Mitra, Debasis [Department of Computer Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)

2011-10-01

Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30 cmx30 cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes ({approx}0.03 L) using GEM-based Muon Tomography.

Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a muon tomography station based on GEM detectors

International Nuclear Information System (INIS)

Gnanvo, Kondo; Grasso, Leonard V.; Hohlmann, Marcus; Locke, Judson B.; Quintero, Amilkar; Mitra, Debasis

2011-01-01

Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30 cmx30 cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes (∼0.03 L) using GEM-based Muon Tomography.

Photoacoustic projection imaging using an all-optical detector array

Science.gov (United States)

Bauer-Marschallinger, J.; Felbermayer, K.; Berer, T.

2018-02-01

We present a prototype for all-optical photoacoustic projection imaging. By generating projection images, photoacoustic information of large volumes can be retrieved with less effort compared to common photoacoustic computed tomography where many detectors and/or multiple measurements are required. In our approach, an array of 60 integrating line detectors is used to acquire photoacoustic waves. The line detector array consists of fiber-optic MachZehnder interferometers, distributed on a cylindrical surface. From the measured variation of the optical path lengths of the interferometers, induced by photoacoustic waves, a photoacoustic projection image can be reconstructed. The resulting images represent the projection of the three-dimensional spatial light absorbance within the imaged object onto a two-dimensional plane, perpendicular to the line detector array. The fiber-optic detectors achieve a noise-equivalent pressure of 24 Pascal at a 10 MHz bandwidth. We present the operational principle, the structure of the array, and resulting images. The system can acquire high-resolution projection images of large volumes within a short period of time. Imaging large volumes at high frame rates facilitates monitoring of dynamic processes.

Advances in Gamma-Ray Imaging with Intensified Quantum-Imaging Detectors

Science.gov (United States)

Han, Ling

Nuclear medicine, an important branch of modern medical imaging, is an essential tool for both diagnosis and treatment of disease. As the fundamental element of nuclear medicine imaging, the gamma camera is able to detect gamma-ray photons emitted by radiotracers injected into a patient and form an image of the radiotracer distribution, reflecting biological functions of organs or tissues. Recently, an intensified CCD/CMOS-based quantum detector, called iQID, was developed in the Center for Gamma-Ray Imaging. Originally designed as a novel type of gamma camera, iQID demonstrated ultra-high spatial resolution (advancing this conceptually-proven gamma-ray imaging technology to make it ready for both preclinical and clinical applications. To start with, a Monte Carlo simulation of the key light-intensification device, i.e. the image intensifier, was developed, which revealed the dominating factor(s) that limit energy resolution performance of the iQID cameras. For preclinical imaging applications, a previously-developed iQID-based single-photon-emission computed-tomography (SPECT) system, called FastSPECT III, was fully advanced in terms of data acquisition software, system sensitivity and effective FOV by developing and adopting a new photon-counting algorithm, thicker columnar scintillation detectors, and system calibration method. Originally designed for mouse brain imaging, the system is now able to provide full-body mouse imaging with sub-350-micron spatial resolution. To further advance the iQID technology to include clinical imaging applications, a novel large-area iQID gamma camera, called LA-iQID, was developed from concept to prototype. Sub-mm system resolution in an effective FOV of 188 mm x 188 mm has been achieved. The camera architecture, system components, design and integration, data acquisition, camera calibration, and performance evaluation are presented in this work. Mounted on a castered counter-weighted clinical cart, the camera also features

Reducing image noise in computed tomography (CT) colonography: effect of an integrated circuit CT detector.

Science.gov (United States)

Liu, Yu; Leng, Shuai; Michalak, Gregory J; Vrieze, Thomas J; Duan, Xinhui; Qu, Mingliang; Shiung, Maria M; McCollough, Cynthia H; Fletcher, Joel G

2014-01-01

To investigate whether the integrated circuit (IC) detector results in reduced noise in computed tomography (CT) colonography (CTC). Three hundred sixty-six consecutive patients underwent clinically indicated CTC using the same CT scanner system, except for a difference in CT detectors (IC or conventional). Image noise, patient size, and scanner radiation output (volume CT dose index) were quantitatively compared between patient cohorts using each detector system, with separate comparisons for the abdomen and pelvis. For the abdomen and pelvis, despite significantly larger patient sizes in the IC detector cohort (both P 0.18). Based on the observed image noise reduction, radiation dose could alternatively be reduced by approximately 20% to result in similar levels of image noise. Computed tomography colonography images acquired using the IC detector had significantly lower noise than images acquired using the conventional detector. This noise reduction can permit further radiation dose reduction in CTC.

Implementation of an image acquisition and processing system based on FlexRIO, CameraLink and areaDetector

Energy Technology Data Exchange (ETDEWEB)

Esquembri, S.; Ruiz, M. [Instrumentation and Applied Acoustic Research Group, Technical University of Madrid (UPM), Madrid (Spain); Barrera, E., E-mail: eduardo.barrera@upm.es [Instrumentation and Applied Acoustic Research Group, Technical University of Madrid (UPM), Madrid (Spain); Sanz, D.; Bustos, A. [Instrumentation and Applied Acoustic Research Group, Technical University of Madrid (UPM), Madrid (Spain); Castro, R.; Vega, J. [National Fusion Laboratory, CIEMAT, Madrid (Spain)

2016-11-15

Highlights: • The system presented acquires and process images from any CameraLink compliant camera. • The frame grabber implanted with FlexRIO technology have image time stamping and preprocessing capabilities. • The system is integrated into EPICS using areaDetector for a flexible configuration of image the acquisition and processing chain. • Is fully compatible with the architecture of the ITER Fast Controllers. - Abstract: Image processing systems are commonly used in current physics experiments, such as nuclear fusion experiments. These experiments usually require multiple cameras with different resolutions, framerates and, frequently, different software drivers. The integration of heterogeneous types of cameras without a unified hardware and software interface increases the complexity of the acquisition system. This paper presents the implementation of a distributed image acquisition and processing system for CameraLink cameras. This system implements a camera frame grabber using Field Programmable Gate Arrays (FPGAs), a reconfigurable hardware platform that allows for image acquisition and real-time preprocessing. The frame grabber is integrated into Experimental Physics and Industrial Control System (EPICS) using the areaDetector EPICS software module, which offers a common interface shared among tens of cameras to configure the image acquisition and process these images in a distributed control system. The use of areaDetector also allows the image processing to be parallelized and concatenated using: multiple computers; areaDetector plugins; and the areaDetector standard type for data, NDArrays. The architecture developed is fully compatible with ITER Fast Controllers and the entire system has been validated using a camera hardware simulator that stream videos from fusion experiment databases.

Scintillating-fiber imaging detector for 14-MeV neutrons

International Nuclear Information System (INIS)

Ress, D.; Lerche, R.A.; Ellis, R.J.; Heaton, G.W.; Nelson, M.B.; Mant, G.; Lehr, D.E.

1994-01-01

The authors have created a detector to image the neutrons emitted by imploded inertial-confinement fusion targets. The 14-MeV neutrons, which are produced by deuterium-tritium fusion events in the target, pass through an aperture to create an image on the detector. The neutron radiation is converted to blue light (430 nm) with a 20-cm-square array of plastic scintillating fibers. Each fiber is 10-cm long with a 1-mm-square cross section; approximately 35-thousand fibers make up the array. The resulting blue-light image is reduced and amplified by a sequence of fiber-optic tapers and image intensifiers, then acquired by a CCD camera. The fiber-optic readout system was tested optically for overall throughput the resolution. The authors plan to characterize the scintillator array reusing an ion-beam neutron source as well as DT-fusion neutrons emitted by inertial confinement targets. Characterization experiments will measure the light-production efficiency, spatial resolution, and neutron scattering within the detector. Several neutron images of laser-fusion targets have been obtained with the detector. Several neutron images of laser-fusion targets have been obtained with the detector. They describe the detector and their characterization methods, present characterization results, and give examples of the neutron images

Recent advances with a hybrid micro-pattern gas detector operated in low pressure H2 and He, for AT-TPC applications

Directory of Open Access Journals (Sweden)

Cortesi Marco

2018-01-01

Full Text Available In view of a possible application as a charge-particle track readout for an Active-Target Time Projection Chamber (AT-TPC, the operational properties and performances of a hybrid Micro-Pattern Gaseous Detector (MPGD were investigated in pure low-pressure Hydrogen (H2 and Helium (He. The detector consists of a MICROMEsh GAseous Structure (MICROMEGAS coupled to a two-cascade THick Gaseous Electron Multiplier (THGEM as a pre-amplification stage. This study reports the effective gain dependence of the hybrid-MPGD at relevant pressure (in the range of 200-760 torr for different detector arrangements. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particularly for applications of MPGD end-cap readout for active-target Time Projection Chambers (TPC in the field of nuclear physics and nuclear astrophysics.

Characterizing the response of a scintillator-based detector to single electrons

International Nuclear Information System (INIS)

Sang, Xiahan; LeBeau, James M.

2016-01-01

Here we report the response of a high angle annular dark field scintillator-based detector to single electrons. We demonstrate that care must be taken when determining the single electron intensity as significant discrepancies can occur when quantifying STEM images with different methods. To account for the detector response, we first image the detector using very low beam currents (∼8 fA), and subsequently model the interval between consecutive single electrons events. We find that single electrons striking the detector present a wide distribution of intensities, which we show is not described by a simple function. Further, we present a method to accurately account for the electrons within the incident probe when conducting quantitative imaging. The role detector settings play on determining the single electron intensity is also explored. Finally, we extend our analysis to describe the response of the detector to multiple electron events within the dwell interval of each pixel. - Highlights: • We show that the statistical description of single electron response of scintillator based detectors can be measured using a combination of small beam currents and short dwell times. • The average intensity from the probability distribution function can be used to normalize STEM images regardless of beam current and contrast settings. • We obtain consistent QSTEM normalization results from the single electron method and the conventional detector scan method.

Ultra-thin infrared metamaterial detector for multicolor imaging applications.

Science.gov (United States)

Montoya, John A; Tian, Zhao-Bing; Krishna, Sanjay; Padilla, Willie J

2017-09-18

The next generation of infrared imaging systems requires control of fundamental electromagnetic processes - absorption, polarization, spectral bandwidth - at the pixel level to acquire desirable information about the environment with low system latency. Metamaterial absorbers have sparked interest in the infrared imaging community for their ability to enhance absorption of incoming radiation with color, polarization and/or phase information. However, most metamaterial-based sensors fail to focus incoming radiation into the active region of a ultra-thin detecting element, thus achieving poor detection metrics. Here our multifunctional metamaterial absorber is directly integrated with a novel mid-wave infrared (MWIR) and long-wave infrared (LWIR) detector with an ultra-thin (~λ/15) InAs/GaSb Type-II superlattice (T2SL) interband cascade detector. The deep sub-wavelength metamaterial detector architecture proposed and demonstrated here, thus significantly improves the detection quantum efficiency (QE) and absorption of incoming radiation in a regime typically dominated by Fabry-Perot etalons. Our work evinces the ability of multifunctional metamaterials to realize efficient wavelength selective detection across the infrared spectrum for enhanced multispectral infrared imaging applications.

Dynamic chest radiography: flat-panel detector (FPD) based functional X-ray imaging.

Science.gov (United States)

Tanaka, Rie

2016-07-01

Dynamic chest radiography is a flat-panel detector (FPD)-based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view (FOV) of FPDs permits real-time observation of the entire lungs and simultaneous right-and-left evaluation of diaphragm kinetics. Most importantly, dynamic chest radiography provides pulmonary ventilation and circulation findings as slight changes in pixel value even without the use of contrast media; the interpretation is challenging and crucial for a better understanding of pulmonary function. The basic concept was proposed in the 1980s; however, it was not realized until the 2010s because of technical limitations. Dynamic FPDs and advanced digital image processing played a key role for clinical application of dynamic chest radiography. Pulmonary ventilation and circulation can be quantified and visualized for the diagnosis of pulmonary diseases. Dynamic chest radiography can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. Here, we focus on the evaluation of pulmonary ventilation and circulation. This review article describes the basic mechanism of imaging findings according to pulmonary/circulation physiology, followed by imaging procedures, analysis method, and diagnostic performance of dynamic chest radiography.

A Thermal Imaging Instrument with Uncooled Detectors

Science.gov (United States)

Joseph, A. T.; Barrentine, E. M.; Brown, A. D.

2017-12-01

In this work, we perform an instrument concept study for sustainable thermal imaging over land with uncooled detectors. The National Research Council's Committee on Implementation of a Sustained Land Imaging Program has identified the inclusion of a thermal imager as critical for both current and future land imaging missions. Such an imaging instrument operating in two bands located at approximately 11 and 12 microns (for example, in Landsat 8, and also Landsat 9 when launched) will provide essential information for furthering our hydrologic understanding at scales of human influence, and produce field-scale moisture information through accurate retrievals of evapotranspiration (ET). Landsat 9 is slated to recycle the TIRS-2 instrument launched with Landsat 8 that uses cooled quantum well infrared photodetectors (QWIPs), hence requiring expensive and massive cryocooler technology to achieve its required spectral and spatial accuracies. Our goal is to conceptualize and develop a thermal imaging instrument which leverages recent and imminent technology advances in uncooled detectors. Such detector technology will offer the benefit of greatly reduced instrument cost, mass, and power at the expense of some acceptable loss in detector sensitivity. It would also allow a thermal imaging instrument to be fielded on board a low-cost platform, e.g., a CubeSat. Sustained and enhanced land imaging is crucial for providing high-quality science data on change in land use, forest health, crop status, environment, and climate. Accurate satellite mapping of ET at the agricultural field scale (the finest spatial scale of the environmental processes of interest) requires high-quality thermal data to produce the corresponding accurate land surface temperature (LST) retrievals used to drive an ET model. Such an imaging instrument would provide important information on the following: 1) the relationship between land-use and land/water management practices and water use dynamics; 2) the

X-ray imaging bilinear staggered GaAs detectors

Energy Technology Data Exchange (ETDEWEB)

Achmadullin, R.A.; Dvoryankin, V.F. E-mail: vfd217@ire216.msk.su; Dvoryankina, G.G.; Dikaev, Y.M.Yu.M.; Krikunov, A.I.; Kudryashov, A.A.; Panova, T.M.; Petrov, A.G.; Telegin, A.A

2004-09-21

The multichannel bilinear X-ray detector based on epitaxial GaAs structures is developed to obtain a digital X-ray image. Each detector operates in photovoltaic mode without reverse bias that enables almost complete elimination of detector noise arising due to leakage currents. The sensitivity range of the epitaxial GaAs photovoltaic X-ray detector covers the effective energies from 8 to 120 keV. A maximum response of the detector operating in the short-circuit mode was observed at an energy of 35 keV and amounted to 30 {mu}A min/(Gy cm{sup 2}). The multichannel detector was made of 1024 pixels with pitch of 0.8 mm. The spatial resolution of double staggered sensor row is twice as high as the resolution of that of single sensor row with the same pitch. Measured spatial resolution is 1.2 line-pairs/mm, contrast sensitivity not worse 1% and dynamic range defined as the ratio of maximum detectable X-ray signal to electronic noise level more than 2000 are received.

X-ray imaging bilinear staggered GaAs detectors

International Nuclear Information System (INIS)

Achmadullin, R.A.; Dvoryankin, V.F.; Dvoryankina, G.G.; Dikaev, Y.M.Yu.M.; Krikunov, A.I.; Kudryashov, A.A.; Panova, T.M.; Petrov, A.G.; Telegin, A.A.

2004-01-01

The multichannel bilinear X-ray detector based on epitaxial GaAs structures is developed to obtain a digital X-ray image. Each detector operates in photovoltaic mode without reverse bias that enables almost complete elimination of detector noise arising due to leakage currents. The sensitivity range of the epitaxial GaAs photovoltaic X-ray detector covers the effective energies from 8 to 120 keV. A maximum response of the detector operating in the short-circuit mode was observed at an energy of 35 keV and amounted to 30 μA min/(Gy cm 2 ). The multichannel detector was made of 1024 pixels with pitch of 0.8 mm. The spatial resolution of double staggered sensor row is twice as high as the resolution of that of single sensor row with the same pitch. Measured spatial resolution is 1.2 line-pairs/mm, contrast sensitivity not worse 1% and dynamic range defined as the ratio of maximum detectable X-ray signal to electronic noise level more than 2000 are received

The Use of Radiation Detectors in Medicine: Radiation Detectors for Morphological Imaging (1/3)

CERN Multimedia

CERN. Geneva

2009-01-01

The development of radiation detectors in the field of nuclear and particle physics has had a terrific impact in medical imaging since this latter discipline took off in late ’70 with the invention of the CT scanners. The massive use in High Energy Physics of position sensitive gas detectors, of high Z and high density scintillators coupled to Photomultiplier (PMT) and Position Sensitive Photomultipliers (PSPMT), and of solid state detectors has triggered during the last 30 years a series of novel applications in Medical Imaging with ionizing radiation. The accelerated scientific progression in genetics and molecular biology has finally generated what it is now called Molecular Imaging. This field of research presents additional challenges not only in the technology of radiation detector, but more and more in the ASIC electronics, fast digital readout and parallel software. In this series of three lectures I will try to present how high energy physics and medical imaging development have both benefited by t...

The Use of Radiation Detectors in Medicine: Radiation Detectors for Functional Imaging (2/3)

CERN Multimedia

CERN. Geneva

2009-01-01

The development of radiation detectors in the field of nuclear and particle physics has had a terrific impact in medical imaging since this latter discipline took off in late ’70 with the invention of the CT scanners. The massive use in High Energy Physics of position sensitive gas detectors, of high Z and high density scintillators coupled to Photomultiplier (PMT) and Position Sensitive Photomultipliers (PSPMT), and of solid state detectors has triggered during the last 30 years a series of novel applications in Medical Imaging with ionizing radiation. The accelerated scientific progression in genetics and molecular biology has finally generated what it is now called Molecular Imaging. This field of research presents additional challenges not only in the technology of radiation detector, but more and more in the ASIC electronics, fast digital readout and parallel software. In this series of three lectures I will try to present how high energy physics and medical imaging development have both benefited by t...

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).

Design and evaluation of a SiPM-based large-area detector module for positron emission imaging

Science.gov (United States)

Alva-Sánchez, H.; Murrieta-Rodríguez, T.; Calva-Coraza, E.; Martínez-Dávalos, A.; Rodríguez-Villafuerte, M.

2018-03-01

The design and evaluation of a large-area detector module for positron emission imaging applications, is presented. The module features a SensL ArrayC-60035-64P-PCB solid state detector (8×8 array of tileable silicon photomultipliers by SensL, 7.2 mm pitch) covering a total area of 57.4×57.4 mm2. The detector module was formed using a pixelated array of 40×40 lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystal elements with 1.43 mm pitch. A 7 mm thick coupling light guide was used to allow light sharing between adjacent SiPM. A 16-channel symmetric charge division (SCD) readout board was designed to multiplex the number of signals from 64 to 16 (8 columns and 8 rows) and a center-of-gravity algorithm to identify the position. Data acquisition and digitization was accomplished using a custom-made system based on FPGAs boards. Crystal maps were obtained using 18F-positron sources and Voronoi diagrams were used to correct for geometric distortions and to generate a non-uniformity correction matrix. All measurements were taken at a controlled room temperature of 22oC. The crystal maps showed minor distortion, 90% of the 1600 total crystal elements could be identified, a mean peak-to-valley ratio of 4.3 was obtained and a 10.8% mean energy resolution for 511 keV annihilation photons was determined. The performance of the detector using our own readout board was compared to that using two different commercially readout boards using the same detector module arrangement. We show that these large-area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, excellent energy resolution and detector uniformity and thus, can be used for positron emission imaging applications.

Bio-medical X-ray imaging with spectroscopic pixel detectors

CERN Document Server

Butler, A P H; Tipples, R; Cook, N; Watts, R; Meyer, J; Bell, A J; Melzer, T R; Butler, P H

2008-01-01

The aim of this study is to review the clinical potential of spectroscopic X-ray detectors and to undertake a feasibility study using a novel detector in a clinical hospital setting. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allowing for routine use of spectroscopic bio-medical imaging. We have coined the term MARS (Medipix All Resolution System) for bio-medical images that provide spatial, temporal, and energy information. The full clinical significance of spectroscopic X-ray imaging is difficult to predict but insights can be gained by examining both image reconstruction artifacts and the current uses of dual-energy techniques. This paper reviews the known uses of energy information in vascular imaging and mammography, clinically important fields. It then presents initial results from using Medipix-2, to image human tissues within a clinical radiology department. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allo...

Development and characterisation of a visible light photon counting imaging detector system

CERN Document Server

Barnstedt, J

2002-01-01

We report on the development of a visible light photon counting imaging detector system. The detector concept is based on standard 25 mm diameter microchannel plate image intensifiers made by Proxitronic in Bensheim (Germany). Modifications applied to these image intensifiers are the use of three microchannel plates instead of two and a high resistance ceramics plate used instead of the standard phosphor output screen. A wedge and strip anode mounted directly behind the high resistance ceramics plate was used as a read out device. This wedge and strip anode picks up the image charge of electron clouds emerging from the microchannel plates. The charge pulses are fed into four charge amplifiers and subsequently into a digital position decoding electronics, achieving a position resolution of up to 1024x1024 pixels. Mounting the anode outside the detector tube is a new approach and has the great advantage of avoiding electrical feedthroughs from the anode so that the standard image intensifier fabrication process...

Application of position-sensitive detectors to positron imaging

International Nuclear Information System (INIS)

Yamashita, Takaji; Uchida, Hiroshi; Watanabe, Mitsuo; Omura, Tomohide

1994-01-01

Positron imaging including positron emission tomography (PET) is expected to be a promising tool for basic and clinical research, because it makes possible the study of regional chemistry within multiple organs of the body in living human beings and experimental animals. New schemes of high resolution block detectors have been developed to improve the performance of positron imaging systems, which employ small segments of bismuth germanate (BGO) arrays and position-sensitive photomultiplier tubes (PS-PMT). The coincidence detector resolution of less than 2.0 mm in full width at half maximum was achieved with the detectors, which is very close to the theoretical resolution limit in positron imaging. (author)

Evaluation of PET Imaging Resolution Using 350 mu{m} Pixelated CZT as a VP-PET Insert Detector

Science.gov (United States)

Yin, Yongzhi; Chen, Ximeng; Li, Chongzheng; Wu, Heyu; Komarov, Sergey; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2014-02-01

A cadmium-zinc-telluride (CZT) detector with 350 μm pitch pixels was studied in high-resolution positron emission tomography (PET) imaging applications. The PET imaging system was based on coincidence detection between a CZT detector and a lutetium oxyorthosilicate (LSO)-based Inveon PET detector in virtual-pinhole PET geometry. The LSO detector is a 20 ×20 array, with 1.6 mm pitches, and 10 mm thickness. The CZT detector uses ac 20 ×20 ×5 mm substrate, with 350 μm pitch pixelated anodes and a coplanar cathode. A NEMA NU4 Na-22 point source of 250 μm in diameter was imaged by this system. Experiments show that the image resolution of single-pixel photopeak events was 590 μm FWHM while the image resolution of double-pixel photopeak events was 640 μm FWHM. The inclusion of double-pixel full-energy events increased the sensitivity of the imaging system. To validate the imaging experiment, we conducted a Monte Carlo (MC) simulation for the same PET system in Geant4 Application for Emission Tomography. We defined LSO detectors as a scanner ring and 350 μm pixelated CZT detectors as an insert ring. GATE simulated coincidence data were sorted into an insert-scanner sinogram and reconstructed. The image resolution of MC-simulated data (which did not factor in positron range and acolinearity effect) was 460 μm at FWHM for single-pixel events. The image resolutions of experimental data, MC simulated data, and theoretical calculation are all close to 500 μm FWHM when the proposed 350 μm pixelated CZT detector is used as a PET insert. The interpolation algorithm for the charge sharing events was also investigated. The PET image that was reconstructed using the interpolation algorithm shows improved image resolution compared with the image resolution without interpolation algorithm.

Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

Energy Technology Data Exchange (ETDEWEB)

Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States)

2010-03-15

Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

International Nuclear Information System (INIS)

Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

2010-01-01

Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

The iQID camera: An ionizing-radiation quantum imaging detector

Energy Technology Data Exchange (ETDEWEB)

Miller, Brian W., E-mail: brian.miller@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); College of Optical Sciences, The University of Arizona, Tucson, AZ 85719 (United States); Gregory, Stephanie J.; Fuller, Erin S. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Barrett, Harrison H.; Bradford Barber, H.; Furenlid, Lars R. [Center for Gamma-Ray Imaging, The University of Arizona, Tucson, AZ 85719 (United States); College of Optical Sciences, The University of Arizona, Tucson, AZ 85719 (United States)

2014-12-11

We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detector's response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The confirmed response to this broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated by particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. The spatial location and energy of individual particles are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, excellent detection efficiency for charged particles, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discriminate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is real-time, single-particle digital autoradiography. We present the latest results and discuss potential applications.

Image feature detectors and descriptors foundations and applications

CERN Document Server

Hassaballah, Mahmoud

2016-01-01

This book provides readers with a selection of high-quality chapters that cover both theoretical concepts and practical applications of image feature detectors and descriptors. It serves as reference for researchers and practitioners by featuring survey chapters and research contributions on image feature detectors and descriptors. Additionally, it emphasizes several keywords in both theoretical and practical aspects of image feature extraction. The keywords include acceleration of feature detection and extraction, hardware implantations, image segmentation, evolutionary algorithm, ordinal measures, as well as visual speech recognition. .

An information-theoretical approach to image resolution applied to neutron imaging detectors based upon individual discriminator signals

International Nuclear Information System (INIS)

Clergeau, Jean-Francois; Ferraton, Matthieu; Guerard, Bruno; Khaplanov, Anton; Piscitelli, Francesco; Platz, Martin; Rigal, Jean-Marie; Van Esch, Patrick; Daulle, Thibault

2013-06-01

1D or 2D neutron imaging detectors with individual wire or strip readout using discriminators have the advantage of being able to treat several neutron impacts partially overlapping in time, hence reducing global dead time. A single neutron impact usually gives rise to several discriminator signals. In this paper, we introduce an information-theoretical definition of image resolution. Two point-like spots of neutron impacts with a given distance between them act as a source of information (each neutron hit belongs to one spot or the other), and the detector plus signal treatment is regarded as an imperfect communication channel that transmits this information. The maximal mutual information obtained from this channel as a function of the distance between the spots allows to define a calibration-independent measure of resolution. We then apply this measure to quantify the power of resolution of different algorithms treating these individual discriminator signals which can be implemented in firmware. The method is then applied to different detectors existing at the ILL. Center-of-gravity methods usually improve the resolution over best-wire algorithms which are the standard way of treating these signals. (authors)

An information-theoretical approach to image resolution applied to neutron imaging detectors based upon individual discriminator signals

Energy Technology Data Exchange (ETDEWEB)

Clergeau, Jean-Francois; Ferraton, Matthieu; Guerard, Bruno; Khaplanov, Anton; Piscitelli, Francesco; Platz, Martin; Rigal, Jean-Marie; Van Esch, Patrick [Institut Laue Langevin, Neutron Detector Service, Grenoble (France); Daulle, Thibault [PHELMA Grenoble - INP Grenoble (France)

2013-06-15

1D or 2D neutron imaging detectors with individual wire or strip readout using discriminators have the advantage of being able to treat several neutron impacts partially overlapping in time, hence reducing global dead time. A single neutron impact usually gives rise to several discriminator signals. In this paper, we introduce an information-theoretical definition of image resolution. Two point-like spots of neutron impacts with a given distance between them act as a source of information (each neutron hit belongs to one spot or the other), and the detector plus signal treatment is regarded as an imperfect communication channel that transmits this information. The maximal mutual information obtained from this channel as a function of the distance between the spots allows to define a calibration-independent measure of resolution. We then apply this measure to quantify the power of resolution of different algorithms treating these individual discriminator signals which can be implemented in firmware. The method is then applied to different detectors existing at the ILL. Center-of-gravity methods usually improve the resolution over best-wire algorithms which are the standard way of treating these signals. (authors)

Gamma-ray detectors for breast imaging

Science.gov (United States)

Williams, Mark B.; Goode, Allen R.; Majewski, Stan; Steinbach, Daniela; Weisenberger, Andrew G.; Wojcik, Randolph F.; Farzanpay, Farzin

1997-07-01

Breast cancer is the most common cancer of American women and is the leading cause of cancer-related death among women aged 15 - 54; however recent years have shown that early detection using x-ray mammography can lead to a high probability of cure. However, because of mammography's low positive predictive value, surgical or core biopsy is typically required for diagnosis. In addition, the low radiographic contrast of many nonpalpable breast masses, particularly among women with radiographically dense breasts, results in an overall rate of 10% to 25% for missed tumors. Nuclear imaging of the breast using single gamma emitters (scintimammography) such as (superscript 99m)Tc, or positron emitters such as F-18- fluorodeoxyglucose (FDG) for positron emission tomography (PET), can provide information on functional or metabolic tumor activity that is complementary to the structural information of x-ray mammography, thereby potentially reducing the number of unnecessary biopsies and missed cancers. This paper summarizes recent data on the efficacy of scintimammography using conventional gamma cameras, and describes the development of dedicated detectors for gamma emission breast imaging. The detectors use new, high density crystal scintillators and large area position sensitive photomultiplier tubes (PSPMTs). Detector design, imaging requirements, and preliminary measured imaging performance are discussed.

Design Studies of a CZT-based Detector Combined with a Pixel-Geometry-Matching Collimator for SPECT Imaging.

Science.gov (United States)

Weng, Fenghua; Bagchi, Srijeeta; Huang, Qiu; Seo, Youngho

2013-10-01

Single Photon Emission Computed Tomography (SPECT) suffers limited efficiency due to the need for collimators. Collimator properties largely decide the data statistics and image quality. Various materials and configurations of collimators have been investigated in many years. The main thrust of our study is to evaluate the design of pixel-geometry-matching collimators to investigate their potential performances using Geant4 Monte Carlo simulations. Here, a pixel-geometry-matching collimator is defined as a collimator which is divided into the same number of pixels as the detector's and the center of each pixel in the collimator is a one-to-one correspondence to that in the detector. The detector is made of Cadmium Zinc Telluride (CZT), which is one of the most promising materials for applications to detect hard X-rays and γ -rays due to its ability to obtain good energy resolution and high light output at room temperature. For our current project, we have designed a large-area, CZT-based gamma camera (20.192 cm×20.192 cm) with a small pixel pitch (1.60 mm). The detector is pixelated and hence the intrinsic resolution can be as small as the size of the pixel. Materials of collimator, collimator hole geometry, detection efficiency, and spatial resolution of the CZT detector combined with the pixel-matching collimator were calculated and analyzed under different conditions. From the simulation studies, we found that such a camera using rectangular holes has promising imaging characteristics in terms of spatial resolution, detection efficiency, and energy resolution.

Electronic noise in CT detectors: Impact on image noise and artifacts.

Science.gov (United States)

Duan, Xinhui; Wang, Jia; Leng, Shuai; Schmidt, Bernhard; Allmendinger, Thomas; Grant, Katharine; Flohr, Thomas; McCollough, Cynthia H

2013-10-01

The objective of our study was to evaluate in phantoms the differences in CT image noise and artifact level between two types of commercial CT detectors: one with distributed electronics (conventional) and one with integrated electronics intended to decrease system electronic noise. Cylindric water phantoms of 20, 30, and 40 cm in diameter were scanned using two CT scanners, one equipped with integrated detector electronics and one with distributed detector electronics. All other scanning parameters were identical. Scans were acquired at four tube potentials and 10 tube currents. Semianthropomorphic phantoms were scanned to mimic the shoulder and abdominal regions. Images of two patients were also selected to show the clinical values of the integrated detector. Reduction of image noise with the integrated detector depended on phantom size, tube potential, and tube current. Scans that had low detected signal had the greatest reductions in noise, up to 40% for a 30-cm phantom scanned using 80 kV. This noise reduction translated into up to 50% in dose reduction to achieve equivalent image noise. Streak artifacts through regions of high attenuation were reduced by up to 45% on scans obtained using the integrated detector. Patient images also showed superior image quality for the integrated detector. For the same applied radiation level, the use of integrated electronics in a CT detector showed a substantially reduced level of electronic noise, resulting in reductions in image noise and artifacts, compared with detectors having distributed electronics.

Spectroscopic Imaging Using Ge and CdTe Based Detector Systems for Hard X-ray Applications

Science.gov (United States)

Astromskas, Vytautas

Third generation synchrotron facilities such as the Diamond Light Source (DLS) have a wide range of experiments performed for a wide range of science fields. The DLS operates at energies up to 150 keV which introduces great challenges to radiation detector technology. This work focuses on the requirements that the detector technology faces for X-ray Absorption Fine Structure (XAFS) and powder diffraction experiments in I12 and I15 beam lines, respectively. A segmented HPGe demonstrator detector with in-built charge sensitive CUBE preamplifiers and a Schottky e- collection CdTe Medipix3RX detector systems were investigated to understand the underlying mechanisms that limit spectroscopic, imaging performances and stability and to find ways to overcome or minimise those limitations. The energy resolution and stability of the Ge demonstrator detector was found to have the required characteristics for XAFS measurements. Charge sharing was identified as a limiting factor to the resolution which is going to be addressed in the future development of a full detector system as well as reductions in electronic noise and cross-talk effects. The stability study of the Schottky CdTe Medipix3RX detector showed that polarization is highly dependent on temperature, irradiation duration and incoming flux. A new pixel behaviour called tri-phase (3-P) pixel was identified and a novel method for determining optimum operational conditions was developed. The use of the 3-P pixels as a criterion for depolarization resulted in a stable performance of the detector. Furthermore, the detector was applied in powder diffraction measurement at the I15 beam line and resulted in the detector diffraction pattern matching the simulated data. CdTe Medipix3RX and HEXITEC spectroscopic imaging detectors were applied in identification and discrimination of transitional metals for security application and K-edge subtraction for medical applications. The results showed that both detectors have potential

Cellular automaton-based position sensitive detector equalization

Energy Technology Data Exchange (ETDEWEB)

Ferrando, Nestor [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)], E-mail: nesferjo@upvnet.upv.es; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M. [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

2009-06-01

Indirect position detectors based on scintillator crystals lack of spacial uniformity in their response. This happens due to crystal inhomogeneities and gain differences among the photomultiplier anodes. In order to solve this, PESIC, an integrated front-end for multianode photomultiplier based nuclear imaging devices was created. One of its main features is the digitally programmable gain adjustment for every photomultiplier output. On another front, cellular automata have been proved to be a useful method for dynamic system modeling. In this paper, a cellular automaton which emulates the behavior of the scintillator crystal, the photomultiplier and the front-end is introduced. Thanks to this model, an automatic energy-based calibration of the detector can be done by configuring the cellular automaton with experimental data and making it evolve up to an stable state. This can be useful as a precalibration method of the detector.

Cellular automaton-based position sensitive detector equalization

International Nuclear Information System (INIS)

Ferrando, Nestor; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M.

2009-01-01

Indirect position detectors based on scintillator crystals lack of spacial uniformity in their response. This happens due to crystal inhomogeneities and gain differences among the photomultiplier anodes. In order to solve this, PESIC, an integrated front-end for multianode photomultiplier based nuclear imaging devices was created. One of its main features is the digitally programmable gain adjustment for every photomultiplier output. On another front, cellular automata have been proved to be a useful method for dynamic system modeling. In this paper, a cellular automaton which emulates the behavior of the scintillator crystal, the photomultiplier and the front-end is introduced. Thanks to this model, an automatic energy-based calibration of the detector can be done by configuring the cellular automaton with experimental data and making it evolve up to an stable state. This can be useful as a precalibration method of the detector.

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

International Nuclear Information System (INIS)

Visvikis, D.; Lefevre, T.; Lamare, F.; Kontaxakis, G.; Santos, A.; Darambara, D.

2006-01-01

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

Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam

International Nuclear Information System (INIS)

Silva, A.L.M.; Figueroa, R.; Jaramillo, A.; Carvalho, M.L.; Veloso, J.F.C.A.

2013-01-01

Energy dispersive X-ray fluorescence (EDXRF) imaging systems are of great interest in many applications of different areas, once they allow us to get images of the spatial elemental distribution in the samples. The detector system used in this study is based on a micro patterned gas detector, named Micro-Hole and Strip Plate. The full field of view system, with an active area of 28 × 28 mm 2 presents some important features for EDXRF imaging applications, such as a position resolution below 125 μm, an intrinsic energy resolution of about 14% full width at half maximum for 5.9 keV X-rays, and a counting rate capability of 0.5 MHz. In this work, analysis of human teeth treated by dental amalgam was performed by using the EDXRF imaging system mentioned above. The goal of the analysis is to evaluate the system capabilities in the biomedical field by measuring the drift of the major constituents of a dental amalgam, Zn and Hg, throughout the tooth structures. The elemental distribution pattern of these elements obtained during the analysis suggests diffusion of these elements from the amalgam to teeth tissues. - Highlights: • Demonstration of an EDXRF imaging system based on a 2D-MHSP detector for biological analysis • Evaluation of the drift of the dental amalgam constituents, throughout the teeth • Observation of Hg diffusion, due to hydroxyapatite crystal defects that compose the teeth tissues

Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam

Energy Technology Data Exchange (ETDEWEB)

Silva, A.L.M. [I3N, Physics Dept, University of Aveiro, 3810-193 Aveiro (Portugal); Figueroa, R.; Jaramillo, A. [Physics Department, Universidad de La Frontera, Temuco (Chile); Carvalho, M.L. [Atomic Physics Centre, University of Lisbon, 1649-03 Lisboa (Portugal); Veloso, J.F.C.A., E-mail: joao.veloso@ua.pt [I3N, Physics Dept, University of Aveiro, 3810-193 Aveiro (Portugal)

2013-08-01

Energy dispersive X-ray fluorescence (EDXRF) imaging systems are of great interest in many applications of different areas, once they allow us to get images of the spatial elemental distribution in the samples. The detector system used in this study is based on a micro patterned gas detector, named Micro-Hole and Strip Plate. The full field of view system, with an active area of 28 × 28 mm{sup 2} presents some important features for EDXRF imaging applications, such as a position resolution below 125 μm, an intrinsic energy resolution of about 14% full width at half maximum for 5.9 keV X-rays, and a counting rate capability of 0.5 MHz. In this work, analysis of human teeth treated by dental amalgam was performed by using the EDXRF imaging system mentioned above. The goal of the analysis is to evaluate the system capabilities in the biomedical field by measuring the drift of the major constituents of a dental amalgam, Zn and Hg, throughout the tooth structures. The elemental distribution pattern of these elements obtained during the analysis suggests diffusion of these elements from the amalgam to teeth tissues. - Highlights: • Demonstration of an EDXRF imaging system based on a 2D-MHSP detector for biological analysis • Evaluation of the drift of the dental amalgam constituents, throughout the teeth • Observation of Hg diffusion, due to hydroxyapatite crystal defects that compose the teeth tissues.

A prototype detector using the neutron image intensifier and multi-anode type photomultiplier tube for pulsed neutron imaging

International Nuclear Information System (INIS)

Ishikawa, Hirotaku; Sato, Hirotaka; Hara, Kaoru Y.; Kamiyama, Takashi

2016-01-01

We developed a neutron two-dimensional (2-D) detector for pulsed neutron imaging as a prototype detector, which was composed of a neutron image intensifier and a multi-anode type photomultiplier tube. A neutron transmission spectrum of α-Fe plate was measured by the prototype detector, and compared with the one measured by a typical neutron 2-D detector. The spectrum was in reasonable agreement with the one measured by the typical detector in the neutron wavelength region above 0.15 nm. In addition, a neutron transmission image of a cadmium indicator was obtained by the prototype detector. The usefulness of the prototype detector for pulsed neutron imaging was demonstrated. (author)

Comparison of Thermal Detector Arrays for Off-Axis THz Holography and Real-Time THz Imaging

Directory of Open Access Journals (Sweden)

Erwin Hack

2016-02-01

Full Text Available In terahertz (THz materials science, imaging by scanning prevails when low power THz sources are used. However, the application of array detectors operating with high power THz sources is increasingly reported. We compare the imaging properties of four different array detectors that are able to record THz radiation directly. Two micro-bolometer arrays are designed for infrared imaging in the 8–14 μm wavelength range, but are based on different absorber materials (i vanadium oxide; (ii amorphous silicon; (iii a micro-bolometer array optimized for recording THz radiation based on silicon nitride; and (iv a pyroelectric array detector for THz beam profile measurements. THz wavelengths of 96.5 μm, 118.8 μm, and 393.6 μm from a powerful far infrared laser were used to assess the technical performance in terms of signal to noise ratio, detector response and detectivity. The usefulness of the detectors for beam profiling and digital holography is assessed. Finally, the potential and limitation for real-time digital holography are discussed.

Comparison of Thermal Detector Arrays for Off-Axis THz Holography and Real-Time THz Imaging.

Science.gov (United States)

Hack, Erwin; Valzania, Lorenzo; Gäumann, Gregory; Shalaby, Mostafa; Hauri, Christoph P; Zolliker, Peter

2016-02-06

In terahertz (THz) materials science, imaging by scanning prevails when low power THz sources are used. However, the application of array detectors operating with high power THz sources is increasingly reported. We compare the imaging properties of four different array detectors that are able to record THz radiation directly. Two micro-bolometer arrays are designed for infrared imaging in the 8-14 μm wavelength range, but are based on different absorber materials (i) vanadium oxide; (ii) amorphous silicon; (iii) a micro-bolometer array optimized for recording THz radiation based on silicon nitride; and (iv) a pyroelectric array detector for THz beam profile measurements. THz wavelengths of 96.5 μm, 118.8 μm, and 393.6 μm from a powerful far infrared laser were used to assess the technical performance in terms of signal to noise ratio, detector response and detectivity. The usefulness of the detectors for beam profiling and digital holography is assessed. Finally, the potential and limitation for real-time digital holography are discussed.

Imaging detectors and electronics - A view of the future

International Nuclear Information System (INIS)

Spieler, Helmuth

2004-01-01

Imaging sensors and readout electronics have made tremendous strides in the past two decades. The application of modern semiconductor fabrication techniques and the introduction of customized monolithic integrated circuits have made large scale imaging systems routine in high energy physics. This technology is now finding its way into other areas, such as space missions, synchrotron light sources, and medical imaging. I review current developments and discuss the promise and limits of new technologies. Several detector systems are described as examples of future trends. The discussion emphasizes semiconductor detector systems, but I also include recent developments for large-scale superconducting detector arrays

Lorentz angle studies for the SLD endcap Cerenkov Ring Imaging Detector

International Nuclear Information System (INIS)

Coyle, P.; Cavalli-Sforza, M.; Coyne, D.

1987-11-01

The design of the endcap Cerenkov Ring Imaging Detectors for SLD requires a detailed understanding of how electrons drift in gases under the influence of crossed electric and magnetic fields. In this report, we present recent measurements of Lorentz angles and drift velocities in gases suitable for the endcap CRID photon detectors. We compare these measurements to predictions from a theoretical model; good agreement is observed. Based on our results we present a design for detectors operating in a 0.6 Tesla transverse magnetic field. 14 refs., 10 figs., 4 tabs

Image formation in track-etch detectors: Pt. 4

International Nuclear Information System (INIS)

Ilic, Radomir; Najzer, Mitja

1990-01-01

The radiographic performance of solid state nuclear track detectors was analysed with respect to image quality. Image quality is expressed in terms of three image quality factors: contrast or gradient of the detector, image unsharpness and detail discernment. Equations for the image quality factors were derived from the radiographic transfer function, taking into account image inhomogeneity caused by statistical fluctuations of track density. To find optimal radiographic conditions for a given application, a single quantity called the figure of radiographic merit was defined. It is expressed as the weighted product of the image quality factors. It was found that optimum image quality of a balanced image, characterized by equal importance of all three image quality factors, is obtained at an exposure value (defined as the product of the average visible track area and track density) of unity. (author)

A new gaseous imaging detector for the assay of lymphocyte cultures

International Nuclear Information System (INIS)

Bateman, J.E.; Joyce, A.; Knight, S.C.; Bedford, P.

1991-01-01

Tritium-labelled cell cultures used in studies of lymphocyte proliferation at the Clinical Research Centre are blotted in arrays of 10x6 spots spaced at 6 mm. An imaging detector based on the differential induction signals produced at a central amplifying electrode has been developed for the imaging and assay of these blots. A spatial resolution ≅ 2.5 mm FWHM attained over the aperture of 60 mmx36mm enables the individual spots to be reliably counted. Data is captured in a PC/AT at rates which permit an assay to be completed in typically 30-60 min. The simplicity of both the detector and the readout electronics leads to a low cost system. Images and assay results are presented. (orig.)

Positron annihilation imaging device using multiple offset rings of detectors

International Nuclear Information System (INIS)

Thompson, C.J.

1981-01-01

This patent application relates to a positron annihilation imaging device comprising two or more coaxial circular arrays of detectors (2,2'), with the detectors in one array angularly offset with respect to the detectors in the adjacent array to detect more than one tomographic image simultaneously through different cross-sections of a patient. (author)

A detector insert based on continuous scintillators for hybrid MR–PET imaging of the human brain

Energy Technology Data Exchange (ETDEWEB)

Rato Mendes, P., E-mail: pedro.rato@ciemat.es [CIEMAT, Avenida Complutense 40, 28040 Madrid (Spain); Cuerdo, R.; Sarasola, I.; García de Acilu, P.; Navarrete, J.; Vela, O.; Oller, J.C.; Cela, J.M. [CIEMAT, Avenida Complutense 40, 28040 Madrid (Spain); Núñez, L.; Pastrana, M. [Hospital Universitario Puerta de Hierro Majadahonda, Manuel de Falla 1, 28222 Majadahonda (Spain); Romero, L.; Willmott, C. [CIEMAT, Avenida Complutense 40, 28040 Madrid (Spain)

2013-02-21

We are developing a positron emission tomography (PET) insert for existing magnetic resonance (MR) equipment, aiming at hybrid MR–PET imaging. Our detector block design is based on trapezoid-shaped LYSO:Ce monolithic scintillators coupled to magnetically compatible Hamamatsu S8550-02 silicon avalanche photodiode (APD) matrices with a dedicated ASIC front-end readout from GammaMedica-Ideas (Fornebu, Norway). The detectors are position sensitive, capable of determining the incidence point of 511 keV gammas with an intrinsic spatial resolution on the order of 2 mm by means of supervised learning neural-network (NN) algorithms. These algorithms, apart from providing continuous coordinates, are also intrinsically corrected for depth of interaction effects and thus parallax-free. Recently we have implemented an advanced prototype featuring two heads with four detector blocks each and final front-end and readout electronics, improving the spatial resolution of reconstructed point source images down to 1.7 mm full width at half maximum (FWHM). Presently we are carrying out operational tests of components and systems under magnetic fields using a 3 T MR scanner. In this paper we present a description of our project, a summary of the results obtained with laboratory prototypes, and the strategy to build and install the complete system at the nuclear medicine department of a collaborating hospital.

A detector insert based on continuous scintillators for hybrid MR–PET imaging of the human brain

International Nuclear Information System (INIS)

Rato Mendes, P.; Cuerdo, R.; Sarasola, I.; García de Acilu, P.; Navarrete, J.; Vela, O.; Oller, J.C.; Cela, J.M.; Núñez, L.; Pastrana, M.; Romero, L.; Willmott, C.

2013-01-01

We are developing a positron emission tomography (PET) insert for existing magnetic resonance (MR) equipment, aiming at hybrid MR–PET imaging. Our detector block design is based on trapezoid-shaped LYSO:Ce monolithic scintillators coupled to magnetically compatible Hamamatsu S8550-02 silicon avalanche photodiode (APD) matrices with a dedicated ASIC front-end readout from GammaMedica-Ideas (Fornebu, Norway). The detectors are position sensitive, capable of determining the incidence point of 511 keV gammas with an intrinsic spatial resolution on the order of 2 mm by means of supervised learning neural-network (NN) algorithms. These algorithms, apart from providing continuous coordinates, are also intrinsically corrected for depth of interaction effects and thus parallax-free. Recently we have implemented an advanced prototype featuring two heads with four detector blocks each and final front-end and readout electronics, improving the spatial resolution of reconstructed point source images down to 1.7 mm full width at half maximum (FWHM). Presently we are carrying out operational tests of components and systems under magnetic fields using a 3 T MR scanner. In this paper we present a description of our project, a summary of the results obtained with laboratory prototypes, and the strategy to build and install the complete system at the nuclear medicine department of a collaborating hospital

Comparison of morphological and conventional edge detectors in medical imaging applications

Science.gov (United States)

Kaabi, Lotfi; Loloyan, Mansur; Huang, H. K.

1991-06-01

Recently, mathematical morphology has been used to develop efficient image analysis tools. This paper compares the performance of morphological and conventional edge detectors applied to radiological images. Two morphological edge detectors including the dilation residue found by subtracting the original signal from its dilation by a small structuring element, and the blur-minimization edge detector which is defined as the minimum of erosion and dilation residues of the blurred image version, are compared with the linear Laplacian and Sobel and the non-linear Robert edge detectors. Various structuring elements were used in this study: regular 2-dimensional, and 3-dimensional. We utilized two criterions for edge detector's performance classification: edge point connectivity and the sensitivity to the noise. CT/MR and chest radiograph images have been used as test data. Comparison results show that the blur-minimization edge detector, with a rolling ball-like structuring element outperforms other standard linear and nonlinear edge detectors. It is less noise sensitive, and performs the most closed contours.

Positron annihilation imaging device using multiple offset rings of detectors

International Nuclear Information System (INIS)

Thompson, C.J.

1982-01-01

A means is provided for recording more than one tomographic image simultaneously through different cross-sections of a patient, using positron emission tomography. Separate rings of detectors are used to construct every odd-numbered slice, and coincident events that occur between adjacent rings of detectors provide a center or even-numbered slice. Detector rings are offset with respect to one another by half the angular separation of the detectors, allowing an image to be reconstructed from the central slice without the necessity of physically rotating the detector array while accumulating data

Upgrade of the Detector for Imaging of Explosions

Science.gov (United States)

Shekhtman, L. I.; Aulchenko, V. M.; Kudryavtsev, V. N.; Kutovenko, V. D.; Titov, V. M.; Zhulanov, V. V.; Pruuel, E. L.; Ten, K. A.; Tolochko, B. P.

Methods of dynamic imaging of explosions at a synchrotron radiation (SR) beam and small-angle X-ray scattering experiments with exploding samples are being developed in the Siberian Synchrotron Radiation Center (SSRC) at the Budker Institute of Nuclear Physics for more than fifteen years. The detector for imaging of explosions (DIMEX) was developed for these purposes and successfully operating at the beam line 0 at the VEPP-3 storage ring and at the beam line 8 at the VEPP-4 M storage ring. The DIMEX is based on gas technology and allow to measure SR flux as a function of position and time with spatial resolution of ∼200 μm (FWHM), maximum frame rate of 2 MHz and time resolution of ∼80 ns. Maximum value of the SR flux that can be measured by the present detector corresponds to ∼5000 photons/(channel*bunch) (20 keV average energy, channel area 0.1x0.5 mm2, bunch revolution frequency 4 MHz). Maximum number of frames that can be stored in the present detector is 32 and the number of channels with 0.1 mm width is 512. In order to significantly improve the precision of data obtained by the DIMEX an upgrade of the detector has been started. The electronics of the gaseous version of the detector has been changed such that the new detector is able to operate with frame rate of 8 MHz and store data in up to 100 frames. A new ASIC was developed for this purpose called DMXG64A that includes 64 channels with low noise integrator and 100 analogue memory cells in each channel. Input charge can be stored to and read out from analogue cells with maximum frequency 10 MHz. This new version of the detector is called the DIMEX-G and is planned to be used at the VEPP-3 storage ring and for SAXS studies at the VEPP-4 M storage ring. For imaging of explosions at the beam line 8 at the VEPP-4 M storage ring, where SR flux is expected to be about 10-100 times higher than at the VEPP-3, a new detector based on Si micro-strip technology is being developed. Si micro-strip sensors with

First observation of Cherenkov ring images using hybrid photon detectors

International Nuclear Information System (INIS)

Albrecht, E.; Wilkinson, G.; Bibby, J.H.; Giles, R.; Harnew, N.; Smale, N.; Brook, N.H.; Halley, A.W.; O'Shea, V.; French, M.; Gibson, V.; Wotton, S.A.; Schomaker, R.

1998-01-01

A ring-imaging Cherenkov detector, equipped with hybrid photon detectors, has been operated in a charged-particle beam. Focussed ring images from various particle types were detected using silica aerogel, air and C 4 F 10 gas radiators. The detector, a prototype for the CERN LHC-B experiment, is described and first observations are reported. (orig.)

First observation of Cherenkov ring images using hybrid photon detectors

Energy Technology Data Exchange (ETDEWEB)

Albrecht, E.; Wilkinson, G. [European Organization for Nuclear Research, Geneva (Switzerland). Div. Particle Physics Experiments; Barber, G.; Duane, A.; John, M.; Miller, D.G.; Websdale, D. [Imperial College of Science Technology and Medicine, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Bibby, J.H.; Giles, R.; Harnew, N.; Smale, N. [University of Oxford, Department of Nuclear Physics, Keble Road, Oxford OX1 3RH (United Kingdom); Brook, N.H.; Halley, A.W.; O`Shea, V. [University of Glasgow, Department of Physics, Glasgow G12 8QQ (United Kingdom); French, M. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Gibson, V.; Wotton, S.A. [University of Cambridge, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE (United Kingdom); Schomaker, R. [Delft Electronic Products BV, 9300 AB Roden (Netherlands)

1998-07-11

A ring-imaging Cherenkov detector, equipped with hybrid photon detectors, has been operated in a charged-particle beam. Focussed ring images from various particle types were detected using silica aerogel, air and C{sub 4}F{sub 10} gas radiators. The detector, a prototype for the CERN LHC-B experiment, is described and first observations are reported. (orig.)

Image scanning microscopy using a SPAD detector array (Conference Presentation)

Science.gov (United States)

Castello, Marco; Tortarolo, Giorgio; Buttafava, Mauro; Tosi, Alberto; Sheppard, Colin J. R.; Diaspro, Alberto; Vicidomini, Giuseppe

2017-02-01

The use of an array of detectors can help overcoming the traditional limitation of confocal microscopy: the compromise between signal and theoretical resolution. Each element independently records a view of the sample and the final image can be reconstructed by pixel reassignment or by inverse filtering (e.g. deconvolution). In this work, we used a SPAD array of 25 detectors specifically designed for this goal and our scanning microscopy control system (Carma) to acquire the partial images and to perform online image processing. Further work will be devoted to optimize the image reconstruction step and to improve the fill-factor of the detector.

A comparison of interest point and region detectors on structured, range and texture images

DEFF Research Database (Denmark)

Kazmi, Wajahat; Andersen, Hans Jørgen

2015-01-01

)) and corner based detectors (such as Hessian and Harris with both Affine/Laplace variants, SURF with determinant of Hessian based corners and SIFT with difference of Gaussians) acquired more than 90% mean average precision, whereas on range images, homogeneous region detector did not work well. TLR offered...... and textured images. It is also shown that in a bi-channel approach, combining surface and edge regions (MSER and TLR) boosts the overall performance. Among the descriptors, SIFT and SURF generally offer higher performance but low dimensional descriptors such as Steerable Filters follow closely....

Laser system for testing radiation imaging detector circuits

Science.gov (United States)

Zubrzycka, Weronika; Kasinski, Krzysztof

2015-09-01

Performance and functionality of radiation imaging detector circuits in charge and position measurement systems need to meet tight requirements. It is therefore necessary to thoroughly test sensors as well as read-out electronics. The major disadvantages of using radioactive sources or particle beams for testing are high financial expenses and limited accessibility. As an alternative short pulses of well-focused laser beam are often used for preliminary tests. There are number of laser-based devices available on the market, but very often their applicability in this field is limited. This paper describes concept, design and validation of laser system for testing silicon sensor based radiation imaging detector circuits. The emphasis is put on keeping overall costs low while achieving all required goals: mobility, flexible parameters, remote control and possibility of carrying out automated tests. The main part of the developed device is an optical pick-up unit (OPU) used in optical disc drives. The hardware includes FPGA-controlled circuits for laser positioning in 2 dimensions (horizontal and vertical), precision timing (frequency and number) and amplitude (diode current) of short ns-scale (3.2 ns) light pulses. The system is controlled via USB interface by a dedicated LabVIEW-based application enabling full manual or semi-automated test procedures.

Transmission diamond imaging detector

Energy Technology Data Exchange (ETDEWEB)

Smedley, John, E-mail: smedley@bnl.gov; Pinelli, Don; Gaoweia, Mengjia [Brookhaven National Laboratory, Upton, NY (United States); Muller, Erik; Ding, Wenxiang; Zhou, Tianyi [Stony Brook University, Stony Brook, NY (United States); Bohon, Jen [Case Center for Synchrotron Biosciences, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH (United States)

2016-07-27

Many modern synchrotron techniques are trending toward use of high flux beams and/or beams which require enhanced stability and precise understanding of beam position and intensity from the front end of the beamline all the way to the sample. For high flux beams, major challenges include heat load management in optics (including the vacuum windows) and a mechanism of real-time volumetric measurement of beam properties such as flux, position, and morphology. For beam stability in these environments, feedback from such measurements directly to control systems for optical elements or to sample positioning stages would be invaluable. To address these challenges, we are developing diamond-based instrumented vacuum windows with integrated volumetric x-ray intensity, beam profile and beam-position monitoring capabilities. A 50 µm thick single crystal diamond has been lithographically patterned to produce 60 µm pixels, creating a >1kilopixel free-standing transmission imaging detector. This device, coupled with a custom, FPGA-based readout, has been used to image both white and monochromatic x-ray beams and capture the last x-ray photons at the National Synchrotron Light Source (NSLS). This technology will form the basis for the instrumented end-station window of the x-ray footprinting beamline (XFP) at NSLS-II.

Optimization of Proton CT Detector System and Image Reconstruction Algorithm for On-Line Proton Therapy.

Directory of Open Access Journals (Sweden)

Chae Young Lee

Full Text Available The purposes of this study were to optimize a proton computed tomography system (pCT for proton range verification and to confirm the pCT image reconstruction algorithm based on projection images generated with optimized parameters. For this purpose, we developed a new pCT scanner using the Geometry and Tracking (GEANT 4.9.6 simulation toolkit. GEANT4 simulations were performed to optimize the geometric parameters representing the detector thickness and the distance between the detectors for pCT. The system consisted of four silicon strip detectors for particle tracking and a calorimeter to measure the residual energies of the individual protons. The optimized pCT system design was then adjusted to ensure that the solution to a CS-based convex optimization problem would converge to yield the desired pCT images after a reasonable number of iterative corrections. In particular, we used a total variation-based formulation that has been useful in exploiting prior knowledge about the minimal variations of proton attenuation characteristics in the human body. Examinations performed using our CS algorithm showed that high-quality pCT images could be reconstructed using sets of 72 projections within 20 iterations and without any streaks or noise, which can be caused by under-sampling and proton starvation. Moreover, the images yielded by this CS algorithm were found to be of higher quality than those obtained using other reconstruction algorithms. The optimized pCT scanner system demonstrated the potential to perform high-quality pCT during on-line image-guided proton therapy, without increasing the imaging dose, by applying our CS based proton CT reconstruction algorithm. Further, we make our optimized detector system and CS-based proton CT reconstruction algorithm potentially useful in on-line proton therapy.

2D dose distribution images of a hybrid low field MRI-γ detector

Energy Technology Data Exchange (ETDEWEB)

Abril, A., E-mail: ajabrilf@unal.edu.co; Agulles-Pedrós, L., E-mail: lagullesp@unal.edu.co [Medical Physics Group, Physics department, Universidad Nacional de Colombia, Bogotá (Colombia)

2016-07-07

The proposed hybrid system is a combination of a low field MRI and dosimetric gel as a γ detector. The readout system is based on the polymerization process induced by the gel radiation. A gel dose map is obtained which represents the functional part of hybrid image alongside with the anatomical MRI one. Both images should be taken while the patient with a radiopharmaceutical is located inside the MRI system with a gel detector matrix. A relevant aspect of this proposal is that the dosimetric gel has never been used to acquire medical images. The results presented show the interaction of the {sup 99m}Tc source with the dosimetric gel simulated in Geant4. The purpose was to obtain the planar γ 2D-image. The different source configurations are studied to explore the ability of the gel as radiation detector through the following parameters; resolution, shape definition and radio-pharmaceutical concentration.

2D dose distribution images of a hybrid low field MRI-γ detector

International Nuclear Information System (INIS)

Abril, A.; Agulles-Pedrós, L.

2016-01-01

The proposed hybrid system is a combination of a low field MRI and dosimetric gel as a γ detector. The readout system is based on the polymerization process induced by the gel radiation. A gel dose map is obtained which represents the functional part of hybrid image alongside with the anatomical MRI one. Both images should be taken while the patient with a radiopharmaceutical is located inside the MRI system with a gel detector matrix. A relevant aspect of this proposal is that the dosimetric gel has never been used to acquire medical images. The results presented show the interaction of the "9"9"mTc source with the dosimetric gel simulated in Geant4. The purpose was to obtain the planar γ 2D-image. The different source configurations are studied to explore the ability of the gel as radiation detector through the following parameters; resolution, shape definition and radio-pharmaceutical concentration.

2D dose distribution images of a hybrid low field MRI-γ detector

Science.gov (United States)

Abril, A.; Agulles-Pedrós, L.

2016-07-01

The proposed hybrid system is a combination of a low field MRI and dosimetric gel as a γ detector. The readout system is based on the polymerization process induced by the gel radiation. A gel dose map is obtained which represents the functional part of hybrid image alongside with the anatomical MRI one. Both images should be taken while the patient with a radiopharmaceutical is located inside the MRI system with a gel detector matrix. A relevant aspect of this proposal is that the dosimetric gel has never been used to acquire medical images. The results presented show the interaction of the 99mTc source with the dosimetric gel simulated in Geant4. The purpose was to obtain the planar γ 2D-image. The different source configurations are studied to explore the ability of the gel as radiation detector through the following parameters; resolution, shape definition and radio-pharmaceutical concentration.

SU-E-I-51: Quantitative Assessment of X-Ray Imaging Detector Performance in a Clinical Setting - a Simple Approach Using a Commercial Instrument

Energy Technology Data Exchange (ETDEWEB)

Sjoeberg, J; Bujila, R; Omar, A; Nowik, P; Mobini-Kesheh, S; Lindstroem, J [Karolinska University Hospital, Solna (Sweden)

2015-06-15

Purpose: To measure and compare the performance of X-ray imaging detectors in a clinical setting using a dedicated instrument for the quantitative determination of detector performance. Methods: The DQEPro (DQE Instruments Inc., London, Ontario Canada) was used to determine the MTF, NPS and DQE using an IEC compliant methodology for three different imaging modalities: conventional radiography (CsI-based detector), general-purpose radioscopy (CsI-based detector), and mammography (a-Se based detector). The radiation qualities (IEC) RQA-5 and RQA-M-2 were used for the CsI-based and a-Se-based detectors, respectively. The DQEPro alleviates some of the difficulties associated with DQE measurements by automatically positioning test devices over the detector, guiding the user through the image acquisition process and providing software for calculations. Results: A comparison of the NPS showed that the image noise of the a-Se detector was less correlated than the CsI detectors. A consistently higher performance was observed for the a-Se detector at all spatial frequencies (MTF: 0.97@0.25 cy/mm, DQE: 0.72@0.25 cy/mm) and the DQE drops off slower than for the CsI detectors. The CsI detector used for conventional radiography displayed a higher performance at low spatial frequencies compared to the CsI detector used for radioscopy (DQE: 0.65 vs 0.60@0.25 cy/mm). However, at spatial frequencies above 1.3 cy/mm, the radioscopy detector displayed better performance than the conventional radiography detector (DQE: 0.35 vs 0.24@2.00 cy/mm). Conclusion: The difference in the MTF, NPS and DQE that was observed for the two different CsI detectors and the a-Se detector reflect the imaging tasks that the different detector types are intended for. The DQEPro has made the determination and calculation of quantitative metrics of X-ray imaging detector performance substantially more convenient and accessible to undertake in a clinical setting.

Detector for imaging and dosimetry of laser-driven epithermal neutrons by alpha conversion

Science.gov (United States)

Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Wilson, L. A.; Ansell, S.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Notley, M.; Raspino, D.; Rusby, D. R.; Borghesi, M.; Rhodes, N. J.; McKenna, P.; Neely, D.; Brenner, C. M.; Kar, S.

2016-10-01

An epithermal neutron imager based on detecting alpha particles created via boron neutron capture mechanism is discussed. The diagnostic mainly consists of a mm thick Boron Nitride (BN) sheet (as an alpha converter) in contact with a non-borated cellulose nitride film (LR115 type-II) detector. While the BN absorbs the neutrons in the thermal and epithermal ranges, the fast neutrons register insignificantly on the detector due to their low neutron capture and recoil cross-sections. The use of solid-state nuclear track detectors (SSNTD), unlike image plates, micro-channel plates and scintillators, provide safeguard from the x-rays, gamma-rays and electrons. The diagnostic was tested on a proof-of-principle basis, in front of a laser driven source of moderated neutrons, which suggests the potential of using this diagnostic (BN+SSNTD) for dosimetry and imaging applications.

Analysis and operation of DePFET X-ray imaging detectors

International Nuclear Information System (INIS)

Lauf, Thomas

2011-01-01

The latest active pixel sensor for X-ray imaging spectroscopy developed at the Max-Planck-Halbleiterlabor (HLL) is the Depleted P-channel Field Effect Transistor (DePFET). This detector type unites detector and first stage amplification and has excellent energy resolution, low noise readout at high speed and low power consumption. This is combined with the possibility of random accessibility of pixels and on-demand readout. In addition it possesses all advantages of a sidewards depleted device, i.e. 100% fill factor and very good quantum efficiency. In the course of the development of DePFET detectors the need of a data analysis software for DePFET devices became apparent. A new tool was developed within the scope of this thesis, which should enable scientists to analyze DePFET data, but also be flexible enough so it can be adapted to new device variants and analysis challenges. A modular concept was thus implemented: a base program running an analysis by individual steps encapsulating algorithms, which can be interchanged. The result is a flexible, adaptable, and expandable analysis software. The software was used to investigate and qualify different structural variants of DePFET detectors. Algorithms to examine detector effects and methods to correct them were developed and integrated into the software. This way, a standard analysis suite for DePFET data was built up which is used at the HLL. Beside the planned use as detector for the wide field imager in the space X-ray observatory IXO, DePFET matrices will be used as focal plane array on the Mercury Imaging X-ray Spectrometer on board the Mercury probe BepiColombo which is scheduled for launch in 2014. The developed analysis software was used in the detector development for this mission to qualify test structures, analyze detector effects and study experimental results. In the course of this development, detector prototypes were studied in respect of linearity, charge collection and detection efficiency in an

Analysis and operation of DePFET X-ray imaging detectors

Energy Technology Data Exchange (ETDEWEB)

Lauf, Thomas

2011-04-28

The latest active pixel sensor for X-ray imaging spectroscopy developed at the Max-Planck-Halbleiterlabor (HLL) is the Depleted P-channel Field Effect Transistor (DePFET). This detector type unites detector and first stage amplification and has excellent energy resolution, low noise readout at high speed and low power consumption. This is combined with the possibility of random accessibility of pixels and on-demand readout. In addition it possesses all advantages of a sidewards depleted device, i.e. 100% fill factor and very good quantum efficiency. In the course of the development of DePFET detectors the need of a data analysis software for DePFET devices became apparent. A new tool was developed within the scope of this thesis, which should enable scientists to analyze DePFET data, but also be flexible enough so it can be adapted to new device variants and analysis challenges. A modular concept was thus implemented: a base program running an analysis by individual steps encapsulating algorithms, which can be interchanged. The result is a flexible, adaptable, and expandable analysis software. The software was used to investigate and qualify different structural variants of DePFET detectors. Algorithms to examine detector effects and methods to correct them were developed and integrated into the software. This way, a standard analysis suite for DePFET data was built up which is used at the HLL. Beside the planned use as detector for the wide field imager in the space X-ray observatory IXO, DePFET matrices will be used as focal plane array on the Mercury Imaging X-ray Spectrometer on board the Mercury probe BepiColombo which is scheduled for launch in 2014. The developed analysis software was used in the detector development for this mission to qualify test structures, analyze detector effects and study experimental results. In the course of this development, detector prototypes were studied in respect of linearity, charge collection and detection efficiency in an

NEW LENSLET BASED IFS WITH HIGH DETECTOR PIXEL EFFICIENCY

Science.gov (United States)

Gong, Qian

2018-01-01

Three IFS types currently used for optical design are: lenslet array, imager slicer, and lenslet array and fiber combined. Lenslet array based Integral Field Spectroscopy (IFS) is very popular for many astrophysics applications due to its compactness, simplicity, as well as cost and mass savings. The disadvantage of lenslet based IFS is its low detector pixel efficiency. Enough spacing is needed between adjacent spectral traces in cross dispersion direction to avoid wavelength cross-talk, because the same wavelength is not aligned to the same column on detector. Such as on a recent exoplanet coronagraph instrument study to support the coming astrophysics decadal survey (LUVOIR), to cover a 45 λ/D Field of View (FOV) with a spectral resolving power of 200 at shortest wavelength, a 4k x 4k detector array is needed. This large format EMCCD pushes the detector into technology development area with a low TRL. Besides the future mission, it will help WFIRST coronagraph IFS by packing all spectra into a smaller area on detector, which will reduce the chance for electrons to be trapped in pixels, and slow the detector degradation during the mission.The innovation we propose here is to increase the detector packing efficiency by grouping a number of lenslets together to form many mini slits. In other words, a number of spots (Point Spread Function at lenslet focus) are aligned into a line to resemble a mini slit. Therefore, wavelength cross-talk is no longer a concern anymore. This combines the advantage of lenslet array and imager slicer together. The isolation rows between spectral traces in cross dispersion direction can be reduced or removed. So the packing efficiency is greatly increased. Furthermore, the today’s microlithography and etching technique is capable of making such a lenslet array, which will relax the detector demand significantly. It will finally contribute to the habitable exoplanets study to analyzing their spectra from direct images. Detailed theory

Visual grading analysis of digital neonatal chest phantom X-ray images: Impact of detector type, dose and image processing on image quality.

Science.gov (United States)

Smet, M H; Breysem, L; Mussen, E; Bosmans, H; Marshall, N W; Cockmartin, L

2018-07-01

To evaluate the impact of digital detector, dose level and post-processing on neonatal chest phantom X-ray image quality (IQ). A neonatal phantom was imaged using four different detectors: a CR powder phosphor (PIP), a CR needle phosphor (NIP) and two wireless CsI DR detectors (DXD and DRX). Five different dose levels were studied for each detector and two post-processing algorithms evaluated for each vendor. Three paediatric radiologists scored the images using European quality criteria plus additional questions on vascular lines, noise and disease simulation. Visual grading characteristics and ordinal regression statistics were used to evaluate the effect of detector type, post-processing and dose on VGA score (VGAS). No significant differences were found between the NIP, DXD and CRX detectors (p>0.05) whereas the PIP detector had significantly lower VGAS (pProcessing did not influence VGAS (p=0.819). Increasing dose resulted in significantly higher VGAS (plevels but not image post-processing changes. VGA showed a DAK/image value above which perceived IQ did not improve, potentially useful for commissioning. • A VGA study detects IQ differences between detectors and dose levels. • The NIP detector matched the VGAS of the CsI DR detectors. • VGA data are useful in setting initial detector air kerma level. • Differences in NNPS were consistent with changes in VGAS.

High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

International Nuclear Information System (INIS)

Tian, Y.; Shimazoe, K.; Yan, X.; Ueda, O.; Ishikura, T.; Fujiwara, T.; Uesaka, M.; Ohno, M.; Tomita, H.; Yoshihara, Y.; Takahashi, H.

2016-01-01

A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Tian, Y., E-mail: cycjty@sophie.q.t.u-tokyo.ac.jp [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimazoe, K.; Yan, X. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ueda, O.; Ishikura, T. [Fuji Electric Co., Ltd., Fuji, Hino, Tokyo 191-8502 (Japan); Fujiwara, T. [National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Uesaka, M.; Ohno, M. [Nuclear Professional School, the University of Tokyo, 2-22 Shirakata-shirane, Tokai, Ibaraki 319-1188 (Japan); Tomita, H. [Department of Quantum Engineering, Nagoya University, Furo, Chikusa, Nagoya 464-8603 (Japan); Yoshihara, Y. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takahashi, H. [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2016-09-11

A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

The imaging pin detector - a simple and effective new imaging device for soft x-rays and soft beta emissions

International Nuclear Information System (INIS)

Bateman, J.E.

1984-01-01

The development of a new bidimensional imaging detector system for soft X and beta radiations is reported. Based on the detection of the differential induction signals on pickup electrodes placed around a point anode in a gas avalanche detector, the system described has achieved a spatial resolution of better than 1mm fwhm over a field of 30mm diameter while preserving excellent pulse height resolution. The present device offers considerable potential as a cheap and robust imaging system for applications in X-ray diffraction and autoradiography. (author)

In-line X-ray lensless imaging with lithium fluoride film detectors

International Nuclear Information System (INIS)

Bonfigli, F.; Cecilia, A.; Bateni, S. Heidari; Nichelatti, E.; Pelliccia, D.; Somma, F.; Vagovic, P.; Vincenti, M.A.; Baumbach, T.; Montereali, R.M.

2013-01-01

In this work, we present preliminary in-line X-ray lensless projection imaging results at a synchrotron facility by using novel solid-state detectors based on non-destructive readout of photoluminescent colour centres in lithium fluoride thin films. The peculiarities of LiF radiation detectors are high spatial resolution on a large field of view, wide dynamic range, versatility and simplicity of use. These properties offered the opportunity to test a broadband X-ray synchrotron source for lensless projection imaging experiments at the TopoTomo beamline of the ANKA synchrotron facility by using a white beam spectrum (3–40 keV). Edge-enhancement effects were observed for the first time on a test object; they are discussed and compared with simulations, on the basis of the colour centre photoluminescence linear response found in the investigated irradiation conditions. -- Highlights: ► We performed broadband X-ray imaging at synchrotron by novel LiF imaging detectors. ► X-ray phase contrast experiments on LiF crystals and thin films were performed. ► Photoluminescent high-quality X-images on a LiF film only 1 μm thick were obtained. ► Edge-enhancement effects were detected and compared with simulations. ► A linearity of colour centre fluorescence response of LiF film was found

The Cerenkov ring-imaging detector recent progress and future development

CERN Document Server

Ekelöf, T J C; Tocqueville, J; Ypsilantis, Thomas

1981-01-01

Results are reported on measurements of Cerenkov ring images using a multistage MWPC with an argon-TEA gas mixture. A specific detector response of N/sub 0/=56 cm/sup -1/ was obtained. It is shown that with some minor modifications to the detector, this value can be raised to N/sub 0/=90 cm/sup -1/. Using an argon-methane-TEA mixture in the MWPC, it is shown that efficient single-photoelectron detection can be achieved with proportional wire amplification without preamplification. A design of a new type of drift chamber (TPC) detector for two-dimensional measurement of the ring image is described. The use of the Cerenkov ring-imaging technique in high- energy physics experimentation is discussed, and in particular a full solid-angle detector for LEP is suggested. (10 refs).

A High-Performance FPGA-Based Image Feature Detector and Matcher Based on the FAST and BRIEF Algorithms

Directory of Open Access Journals (Sweden)

Michał Fularz

2015-10-01

Full Text Available Image feature detection and matching is a fundamental operation in image processing. As the detected and matched features are used as input data for high-level computer vision algorithms, the matching accuracy directly influences the quality of the results of the whole computer vision system. Moreover, as the algorithms are frequently used as a part of a real-time processing pipeline, the speed at which the input image data are handled is also a concern. The paper proposes an embedded system architecture for feature detection and matching. The architecture implements the FAST feature detector and the BRIEF feature descriptor and is capable of establishing key point correspondences in the input image data stream coming from either an external sensor or memory at a speed of hundreds of frames per second, so that it can cope with most demanding applications. Moreover, the proposed design is highly flexible and configurable, and facilitates the trade-off between the processing speed and programmable logic resource utilization. All the designed hardware blocks are designed to use standard, widely adopted hardware interfaces based on the AMBA AXI4 interface protocol and are connected using an underlying direct memory access (DMA architecture, enabling bottleneck-free inter-component data transfers.

New detectors technology for radiology imaging

International Nuclear Information System (INIS)

Cuzin, M.; Peyret, O.

1998-01-01

We summarize the main parameters which describes the radiological image at first and the advantages of pixel detectors. All detectors converts X-rays in charges either with an intermediate step with light or directly in a semi-conductor media. That is true for tomography which is the first domain where digital processing have been taken in account and for radiology where flat panel are now proposed to radiologists. Nevertheless, luminescent stimulated screens are a good way to prepare users with digital radiography. As such technique is not valuable for dynamic acquisition, we describe systems which used standard luminescent screens with CCD cameras or with IIR. Some description and comparison of flat panel independent pixel detectors are given. (authors)

Imaging gaseous detectors and their applications

CERN Document Server

Nappi, Eugenio

2013-01-01

Covers the detector and imaging technology and their numerous applications in nuclear and high energy physics, astrophysics, medicine and radiation measurements Foreword from G. Charpak, awarded the Nobel Prize in Physics for this invention.

Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: Image quality and potential for dose reduction in comparison with screen-film radiography

International Nuclear Information System (INIS)

Volk, M.; Strotzer, M.; Holzkneckt, N.; Manke, C.; Lenhart, M.; Gmeinwieser, J.; Link, J.; Reiser, M.; Feuerback, S.

2000-01-01

AIM: The purpose of this study was to evaluate a large-area, flat-panel X-ray detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si) with respect to skeletal radiography. Conventional images were compared with digital radiographs using identical and reduced radiation doses. MATERIALS AND METHODS: Thirty consecutive patients were studied prospectively using conventional screen-film radiography (SFR; detector dose 2.5 μGy). Digital images were taken from the same patients with detector doses of 2.5, 1.25 and 0.625 μGy, respectively. The active-matrix detector had a panel size of 43 x 43 cm, a matrix of 3 x 3K, and a pixel size of 143 μm. All hard copies were presented in a random order to eight independent observers, who rated image quality according to subjective quality criteria. Results were assessed for significance using the Student's t -test (confidence level 95%). RESULTS: A statistically significant preference for digital over conventional images was revealed for all quality criteria, except for over-exposure (detector dose 2.5 μGy). Digital images with a 50% dose showed a small, statistically not significant, inferiority compared with SFR. The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cortex and trabecula, contrast and overall impression. No statistically significant differences were found with regard to over- and under-exposure and soft tissue presentation. CONCLUSION: Amorphous silicon-based digital radiography yields good image quality. The potential for dose reduction depends on the clinical query. Volk, M. (2000)

State-of-the-art radiation detectors for medical imaging: Demands and trends

International Nuclear Information System (INIS)

Darambara, Dimitra G.

2006-01-01

Over the last half-century a variety of significant technical advances in several scientific fields has been pointing to an exploding growth in the field of medical imaging leading to a better interpretation of more specific anatomical, biochemical and molecular pathways. In particular, the development of novel imaging detectors and readout electronics has been critical to the advancement of medical imaging allowing the invention of breakthrough platforms for simultaneous acquisition of multi-modality images at molecular level. The present paper presents a review of the challenges, demands and constraints on radiation imaging detectors imposed by the nature of the modality and the physics of the imaging source. This is followed by a concise review and perspective on various types of state-of-the-art detector technologies that have been developed to meet these requirements. Trends, prospects and new concepts for future imaging detectors are also highlighted

State-of-the-art radiation detectors for medical imaging: Demands and trends

Energy Technology Data Exchange (ETDEWEB)

Darambara, Dimitra G. [Joint Department of Physics, Royal Marsden Foundation Trust and Institute of Cancer Research, Fulham Road, London SW3 6JJ (United Kingdom)]. E-mail: dimitra.darambara@icr.ac.uk

2006-12-20

Over the last half-century a variety of significant technical advances in several scientific fields has been pointing to an exploding growth in the field of medical imaging leading to a better interpretation of more specific anatomical, biochemical and molecular pathways. In particular, the development of novel imaging detectors and readout electronics has been critical to the advancement of medical imaging allowing the invention of breakthrough platforms for simultaneous acquisition of multi-modality images at molecular level. The present paper presents a review of the challenges, demands and constraints on radiation imaging detectors imposed by the nature of the modality and the physics of the imaging source. This is followed by a concise review and perspective on various types of state-of-the-art detector technologies that have been developed to meet these requirements. Trends, prospects and new concepts for future imaging detectors are also highlighted.

High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

Science.gov (United States)

Callas, J. L.; Mahoney, W. A.; Varnell, L. S.; Wheaton, W. A.

1993-01-01

Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

A tilted fiber-optic plate coupled CCD detector for high resolution neutron imaging

Energy Technology Data Exchange (ETDEWEB)

Kim, Jongyul; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Jongyul; Hwy, Limchang; Kim, Taejoo; Lee, Kyehong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Seungwook [Pusan National Univ., Pusan (Korea, Republic of)

2013-05-15

One of these efforts is that a tilted scintillator geometry and lens coupled CCD detector for neutron imaging system were used to improve spatial resolution in one dimension. The increased spatial resolution in one dimension was applied to fuel cell study. However, a lens coupled CCD detector has lower sensitivity than a fiber-optic plate coupled CCD detector due to light loss. In this research, a tilted detector using fiber-optic plate coupled CCD detector was developed to improve resolution and sensitivity. In addition, a tilted detector can prevent an image sensor from direct radiation damage. Neutron imaging has been used for fuel cell study, lithium ion battery study, and many scientific applications. High quality neutron imaging is demanded for more detailed studies of applications, and spatial resolution should be considered to get high quality neutron imaging. Therefore, there were many efforts to improve spatial resolution.

A possible role for silicon microstrip detectors in nuclear medicine Compton imaging of positron emitters

CERN Document Server

Scannavini, M G; Royle, G J; Cullum, I; Raymond, M; Hall, G; Iles, G

2002-01-01

Collimation of gamma-rays based on Compton scatter could provide in principle high resolution and high sensitivity, thus becoming an advantageous method for the imaging of radioisotopes of clinical interest. A small laboratory prototype of a Compton camera is being constructed in order to initiate studies aimed at assessing the feasibility of Compton imaging of positron emitters. The design of the camera is based on the use of a silicon collimator consisting of a stack of double-sided, AC-coupled microstrip detectors (area 6x6 cm sup 2 , 500 mu m thickness, 128 channels/side). Two APV6 chips are employed for signal readout on opposite planes of each detector. This work presents the first results on the noise performance of the silicon strip detectors. Measurements of the electrical characteristics of the detector are also reported. On the basis of the measured noise, an angular resolution of approximately 5 deg. is predicted for the Compton collimator.

Cherenkov detectors for spatial imaging applications using discrete-energy photons

Energy Technology Data Exchange (ETDEWEB)

Rose, Paul B.; Erickson, Anna S., E-mail: erickson@gatech.edu [Georgia Institute of Technology, Nuclear and Radiological Engineering, G.W. Woodruff School of Mechanical Engineering, 770 State St., Atlanta, Georgia 30332 (United States)

2016-08-14

Cherenkov detectors can offer a significant advantage in spatial imaging applications when excellent timing response, low noise and cross talk, large area coverage, and the ability to operate in magnetic fields are required. We show that an array of Cherenkov detectors with crude energy resolution coupled with monochromatic photons resulting from a low-energy nuclear reaction can be used to produce a sharp image of material while providing large and inexpensive detector coverage. The analysis of the detector response to relative transmission of photons with various energies allows for reconstruction of material's effective atomic number further aiding in high-Z material identification.

Parallel detecting super-resolution microscopy using correlation based image restoration

Science.gov (United States)

Yu, Zhongzhi; Liu, Shaocong; Zhu, Dazhao; Kuang, Cuifang; Liu, Xu

2017-12-01

A novel approach to achieve the image restoration is proposed in which each detector's relative position in the detector array is no longer a necessity. We can identify each detector's relative location by extracting a certain area from one of the detector's image and scanning it on other detectors' images. According to this location, we can generate the point spread functions (PSF) for each detector and perform deconvolution for image restoration. Equipped with this method, the microscope with discretionally designed detector array can be easily constructed without the concern of exact relative locations of detectors. The simulated results and experimental results show the total improvement in resolution with a factor of 1.7 compared to conventional confocal fluorescence microscopy. With the significant enhancement in resolution and easiness for application of this method, this novel method should have potential for a wide range of application in fluorescence microscopy based on parallel detecting.

Pixel detectors for x-ray imaging spectroscopy in space

International Nuclear Information System (INIS)

Treis, J; Andritschke, R; Hartmann, R; Herrmann, S; Holl, P; Lauf, T; Lechner, P; Lutz, G; Meidinger, N; Porro, M; Richter, R H; Schopper, F; Soltau, H; Strueder, L

2009-01-01

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 x 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

Pixel detectors for x-ray imaging spectroscopy in space

Science.gov (United States)

Treis, J.; Andritschke, R.; Hartmann, R.; Herrmann, S.; Holl, P.; Lauf, T.; Lechner, P.; Lutz, G.; Meidinger, N.; Porro, M.; Richter, R. H.; Schopper, F.; Soltau, H.; Strüder, L.

2009-03-01

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 × 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

Pixel detectors for x-ray imaging spectroscopy in space

Energy Technology Data Exchange (ETDEWEB)

Treis, J; Andritschke, R; Hartmann, R; Herrmann, S; Holl, P; Lauf, T; Lechner, P; Lutz, G; Meidinger, N; Porro, M; Richter, R H; Schopper, F; Soltau, H; Strueder, L [MPI Semiconductor Laboratory, Otto-Hahn-Ring 6, D-81739 Munich (Germany)], E-mail: jft@hll.mpg.de

2009-03-15

Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 x 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

Large-area imaging micro-well detectors for high-energy astrophysics

CERN Document Server

Deines-Jones, P; Hunter, S D; Jahoda, K; Owens, S M

2002-01-01

Micro-well detectors are pixelized imaging sensors that can be inexpensively fabricated in very large arrays. Owing to their intrinsic gain and operation at room temperature, they can be instrumented at very low power, per unit area, making them valuable for a variety of space-flight applications where wide-angle X-ray imaging or large-area particle tracking is required. For example, micro-well detectors have been chosen as the focal plane imager for Lobster-ISS, a proposed soft X-ray all-sky monitor. We have fabricated detectors which image X-rays with 200 mu m FWHM resolution at 3 keV. In agreement with other groups using similar geometries, we find nominal proportional counter energy resolution (20% at 6 keV in P-10), and stable operation at gas gains up to 30,000.

Defective pixel map creation based on wavelet analysis in digital radiography detectors

International Nuclear Information System (INIS)

Park, Chun Joo; Lee, Hyoung Koo; Song, William Y.; Achterkirchen, Thorsten Graeve; Kim, Ho Kyung

2011-01-01

The application of digital radiography detectors has attracted increasing attention in both medicine and industry. Since the imaging detectors are fabricated by semiconductor manufacturing process over large areas, defective pixels in the detectors are unavoidable. Moreover, the radiation damage due to the routine use of the detectors progressively increases the density of defective pixels. In this study, we present a method of identifying defective pixels in digital radiography detectors based on wavelet analysis. Artifacts generated due to wavelet transformations have been prevented by an additional local threshold method. The proposed method was applied to a sample digital radiography and the result was promising. The proposed method uses a single pair of dark and white images and does not require them to be corrected in gain-and-offset properties. This method will be helpful for the reliable use of digital radiography detectors through the working lifetime.

Cherenkov Ring Imaging Detector front-end electronics

International Nuclear Information System (INIS)

Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Marshall, D.; Muller, D.; Nagamine, T.; Oxoby, G.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Suekane, F.; Toge, N.; Va'Vra, J.; Williams, S.; Wilson, R.J.; Whitaker, J.S.; Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Morrison, R.; Witherell, M.; Yellin, S.; Coyle, P.; Coyne, D.; Spencer, E.; d'Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Shoup, A.; Stockdale, I.; Jacques, P.; Plano, R.; Stamer, P.; Abe, K.; Hasegawa, K.; Yuta, H.

1990-10-01

The SLD Cherenkov Ring Imaging Detector use a proportional wire detector for which a single channel hybrid has been developed. It consists of a preamplifier, gain selectable amplifier, load driver amplifier, power switching, and precision calibrator. For this hybrid, a bipolar, semicustom integrated circuit has been designed which includes video operational amplifiers for two of the gain stages. This approach allows maximization of the detector volume, allows DC coupling, and enables gain selection. System tests show good noise performance, calibration precision, system linearity, and signal shape uniformity over the full dynamic range. 10 refs., 8 figs

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-04-11

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

Applications of 'edge-on' illuminated porous plate detectors for diagnostic X-ray imaging

CERN Document Server

Shikhaliev, P M

2002-01-01

Scanning X-ray imaging systems for non-invasive diagnostics have several advantages over conventional imaging systems using area detectors. They significantly reduce the detected scatter radiation, cover large areas and potentially provide high spatial resolution. Applications of one-dimensional gaseous detectors and 'edge-on' illuminated silicon strip detectors for scanning imaging systems are currently under intensive investigation. The purpose of this work is to investigate 'edge-on' illuminated Porous Plate (PP) detectors for applications in diagnostic X-ray imaging. MicroChannel Plate (MCP), which is a common type of PP, has previously been investigated as a detector in surface-on illumination mode for medical X-ray imaging. However, its detection efficiency was too low for medical imaging applications. In the present study, the PP are used in the 'edge-on' illumination mode. Furthermore, the structural parameters of different PP types are optimized to improve the detection efficiency in the diagnostic X...

Recent state of CdTe-based radiation detectors

International Nuclear Information System (INIS)

Ohno, R.

2004-01-01

Recent state for development of CdTe-based radiation detectors is reviewed. The progress of the technologies such as the crystal growth of CdTe and CdZnTe, the deposition of electrodes on the crystal, the design of read out ASIC, and the bonding between crystal and ASIC, opened the way for the development of imaging devices for practical uses. A X-ray imager for non destructive inspections and a gamma ray imager for small animal radioisotope experiments or nuclear medicine are presented as examples. (author)

A simple algorithm for estimation of source-to-detector distance in Compton imaging

International Nuclear Information System (INIS)

Rawool-Sullivan, Mohini W.; Sullivan, John P.; Tornga, Shawn R.; Brumby, Steven P.

2008-01-01

Compton imaging is used to predict the location of gamma-emitting radiation sources. The X and Y coordinates of the source can be obtained using a back-projected image and a two-dimensional peak-finding algorithm. The emphasis of this work is to estimate the source-to-detector distance (Z). The algorithm presented uses the solid angle subtended by the reconstructed image at various source-to-detector distances. This algorithm was validated using both measured data from the prototype Compton imager (PCI) constructed at the Los Alamos National Laboratory and simulated data of the same imager. Results show this method can be applied successfully to estimate Z, and it provides a way of determining Z without prior knowledge of the source location. This method is faster than the methods that employ maximum likelihood method because it is based on simple back projections of Compton scatter data

Cerenkov ring imaging detector development at SLAC

International Nuclear Information System (INIS)

Williams, S.H.

1984-06-01

The imaging of Cerenkov light on to photosensitive detectors promises to be a powerful technique for identifying particles in colliding beam spectrometers. Toward this end two and three dimensional imaging photon detectors are being developed at SLAC. The present techniques involve photon conversion using easily ionized exotic chemicals like tetrakisdimethyl-amino-ethylene (TMAE) in a drift and amplifying gas mixture of methane and isobutane. Single photoelectrons from Cerenkov light are currently being drifted 20 cm and a new device under study will be used to study drifting up to 80 cm along a magnetic field. A short description of a large device currently being designed for the SLD spectrometer at the Stanford Linear Collider will be given

Microsecond-scale X-ray imaging with Controlled-Drift Detectors

International Nuclear Information System (INIS)

Castoldi, A.; Galimberti, A.; Guazzoni, C.; Rehak, P.; Strueder, L.

2006-01-01

The Controlled-Drift Detector is a fully-depleted silicon detector that allows 2-D position sensing and energy spectroscopy of X-rays in the range 0.5-20keV with excellent time resolution (few tens of μs) and limited readout channels. In this paper we review the Controlled-Drift Detector operating principle and we present the X-ray imaging and spectroscopic capabilities of Controlled Drift Detectors in microsecond-scale experiments and the more relevant applications fields

Polarization effect of CdZnTe imaging detector based on high energy γ source

International Nuclear Information System (INIS)

Li Miao; Xiao Shali; Wang Xi; Shen Min; Zhang Liuqiang; Cao Yulin; Chen Yuxiao

2011-01-01

The inner electric potential distribution of CdZnTe detector was derived by applying poisson equation with the first type boundary condition, and the polarization effect of CdZnTe pixellated detector for imaging 137 Cs γ source was investigated. The results of numerical calculation and experiment indicate that electric potential distribution is mainly influenced by applied bias for low charge density in CdZnTe crystal and, in turn, there is linear relationship between electric potential distribution and applied bias that induces uniform electric field under low irradiated flux. However, the electric potential appears polarization phenomenon, and the electric field in CdZnTe crystal is distorted when CdZnTe detector is under high irradiated flux. Consequently, charge carriers in CdZnTe crystal drift towards the edge pixels of irradiated region, and hence, the shut-off central pixels are surrounded by a ring of low counting pixels. The polarization effect indeed deteriorates the performance of CdZnTe detector severely and the event counts of edge pixels for irradiated region reduce about 70%. (authors)

Advances in indirect detector systems for ultra high-speed hard X-ray imaging with synchrotron light

Science.gov (United States)

Olbinado, M. P.; Grenzer, J.; Pradel, P.; De Resseguier, T.; Vagovic, P.; Zdora, M.-C.; Guzenko, V. A.; David, C.; Rack, A.

2018-04-01

We report on indirect X-ray detector systems for various full-field, ultra high-speed X-ray imaging methodologies, such as X-ray phase-contrast radiography, diffraction topography, grating interferometry and speckle-based imaging performed at the hard X-ray imaging beamline ID19 of the European Synchrotron—ESRF. Our work highlights the versatility of indirect X-ray detectors to multiple goals such as single synchrotron pulse isolation, multiple-frame recording up to millions frames per second, high efficiency, and high spatial resolution. Besides the technical advancements, potential applications are briefly introduced and discussed.

Dark-field image contrast in transmission scanning electron microscopy: Effects of substrate thickness and detector collection angle

Energy Technology Data Exchange (ETDEWEB)

Woehl, Taylor, E-mail: tjwoehl@umd.edu; Keller, Robert

2016-12-15

An annular dark field (ADF) detector was placed beneath a specimen in a field emission scanning electron microscope operated at 30 kV to calibrate detector response to incident beam current, and to create transmission images of gold nanoparticles on silicon nitride (SiN) substrates of various thicknesses. Based on the linear response of the ADF detector diodes to beam current, we developed a method that allowed for direct determination of the percentage of that beam current forward scattered to the ADF detector from the sample, i.e. the transmitted electron (TE) yield. Collection angles for the ADF detector region were defined using a masking aperture above the detector and were systematically varied by changing the sample to detector distance. We found the contrast of the nanoparticles, relative to the SiN substrate, decreased monotonically with decreasing inner exclusion angle and increasing substrate thickness. We also performed Monte Carlo electron scattering simulations, which showed quantitative agreement with experimental contrast associated with the nanoparticles. Together, the experiments and Monte Carlo simulations revealed that the decrease in contrast with decreasing inner exclusion angle was due to a rapid increase in the TE yield of the low atomic number substrate. Nanoparticles imaged at low inner exclusion angles (<150 mrad) and on thick substrates (>50 nm) showed low image contrast in their centers surrounded by a bright high-contrast halo on their edges. This complex image contrast was predicted by Monte Carlo simulations, which we interpreted in terms of mixing of the nominally bright field (BF) and ADF electron signals. Our systematic investigation of inner exclusion angle and substrate thickness effects on ADF t-SEM imaging provides fundamental understanding of the contrast mechanisms for image formation, which in turn suggest practical limitations and optimal imaging conditions for different substrate thicknesses. - Highlights: • Developed a

Tests of innovative photon detectors and integrated electronics for the large-area CLAS12 ring-imaging Cherenkov detector

Energy Technology Data Exchange (ETDEWEB)

Contalbrigo, M., E-mail: contalbrigo@fe.infn.it

2015-07-01

A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab. Its aim is to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and a densely packed and highly segmented photon detector. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). Extensive tests have been performed on Hamamatsu H8500 and novel flat multi-anode photomultipliers under development and on various types of silicon photomultipliers. A large scale prototype based on 28 H8500 MA-PMTs has been realized and tested with few GeV/c hadron beams at the T9 test-beam facility of CERN. In addition a small prototype was used to study the response of customized SiPM matrices within a temperature interval ranging from 25 down to −25 °C. The preliminary results of the individual photon detector tests and of the prototype performance at the test-beams are here reported.

Image-based deep learning for classification of noise transients in gravitational wave detectors

Science.gov (United States)

Razzano, Massimiliano; Cuoco, Elena

2018-05-01

The detection of gravitational waves has inaugurated the era of gravitational astronomy and opened new avenues for the multimessenger study of cosmic sources. Thanks to their sensitivity, the Advanced LIGO and Advanced Virgo interferometers will probe a much larger volume of space and expand the capability of discovering new gravitational wave emitters. The characterization of these detectors is a primary task in order to recognize the main sources of noise and optimize the sensitivity of interferometers. Glitches are transient noise events that can impact the data quality of the interferometers and their classification is an important task for detector characterization. Deep learning techniques are a promising tool for the recognition and classification of glitches. We present a classification pipeline that exploits convolutional neural networks to classify glitches starting from their time-frequency evolution represented as images. We evaluated the classification accuracy on simulated glitches, showing that the proposed algorithm can automatically classify glitches on very fast timescales and with high accuracy, thus providing a promising tool for online detector characterization.

Beam Studies of the Segmented Resistive WELL: a Potential Thin Sampling Element for Digital Hadron Calorimetry

CERN Document Server

Arazi, Lior; Breskin, Amos; Bressler, Shikma; Moleri, Luca; Natal da Luz, Hugo; Oliveri, Eraldo; Pitt, Michael; Rubin, Adam; Marques Ferreira dos Santos, Joaquim; Calapez Albuquerque Veloso, João Filipe; White, Andrew Paul

2013-01-01

Thick Gas Electron Multipliers (THGEMs) have the potential of constituting thin, robust sampling elements in Digital Hadron Calorimetry (DHCAL) in future colliders. We report on recent beam studies of new single- and double-THGEM-like structures; the multiplier is a Segmented Resistive WELL (SRWELL) - a single-faced THGEM in contact with a segmented resistive layer inductively coupled to readout pads. Several 10$\\times$10 cm$^2$ configurations with a total thickness of 5-6 mm (excluding electronics) with 1 cm$^2$ pads coupled to APV-SRS readout were investigated with muons and pions. Detection efficiencies in the 98$%$ range were recorded with average pad-multiplicity of $\\sim$1.1. The resistive anode resulted in efficient discharge damping, with potential drops of a few volts; discharge probabilities were $\\sim10^{-7}$ for muons and $\\sim10^{-6}$ for pions in the double-stage configuration, at rates of a few kHz/cm$^2$. Further optimization work and research on larger detectors are underway.

The forward ring imaging Cherenkov detector of DELPHI

International Nuclear Information System (INIS)

Adam, W.; Albrecht, E.; Ambec, I.; Augustinus, A.; Barnoux, C.; Bostjancic, B.; Botner, O.; Budziak, A.P.; Caloba, L.P.; Carecchio, P.; Cavalli, P.; Ceelie, L.; Cereseto, R.; Cerutti, G.; Dahl-Jensen, E.; Dam, P.; Damgaard, G.; Koning, N. de; De la Vega, A.S.; Dimitriou, N.; Dulinski, W.; Eek, L.O.; Ekeloef, T.; Erikson, J.; Florek, A.; Florek, B.; Fontanelli, F.; Fontenille, A.; Galuszka, K.; Garcia, J.; Gracco, V.; Hallgren, A.; Hao, W.; Henkes, T.; Isenhower, D.; Johansson, H.; Karvelas, E.; Kindblom, P.; Koene, B.; Korporaal, A.; Kostarakis, P.; Lenzen, G.; Lindqvist, L.E.; Lorenz, P.; Loukas, D.; Lund-Jensen, B.; Maltezos, A.; Markou, A.; Mattsson, L.; Medbo, J.; Michalowski, J.; Montano, F.; Nielsen, B.S.; Ostler, J.M.; Pakonski, K.; Perdikis, C.; Polok, G.; Robohm, A.; Sajot, G.; Sannino, M.; Saragas, E.; Schyns, E.; Squarcia, S.; Stavropoulos, G.; Stodulski, M.; Stopa, Z.; Thadome, J.; Theodosiou, G.E.; Traspedini, L.; Turala, M.; Ullaland, O.; Waerm, A.; Werner, J.; Xyroutsikos, S.; Zavrtanik, M.; Zevgolatakos, E.

1994-01-01

The Forward Ring Imaging Cherenkov detector of the DELPHI experiment at LEP provides hadron identification at polar angles 15 6 F 14 and a volume of gaseous C 4 F 10 , in combination provide coverage of momenta up to 40 GeV/c. A single array of photosensitive Time Projection Chambers registers the impact points of ultraviolet photons from both radiators. The design of the detector and of its readout system is described. First results obtained with a partly installed detector are reported. (orig.)

Taheri-Saramad x-ray detector (TSXD): a novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane.

Science.gov (United States)

Taheri, A; Saramad, S; Ghalenoei, S; Setayeshi, S

2014-01-01

A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 μm, respectively.

Taheri-Saramad x-ray detector (TSXD): A novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane

Energy Technology Data Exchange (ETDEWEB)

Taheri, A., E-mail: at1361@aut.ac.ir; Saramad, S.; Ghalenoei, S.; Setayeshi, S. [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran 15875-4413 (Iran, Islamic Republic of)

2014-01-15

A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 μm, respectively.

Preliminary results from a novel CVD diamond detector system for molecular imaging applications

International Nuclear Information System (INIS)

Mahon, A.R.

1996-01-01

A novel biomolecular imaging system incorporating a Chemical Vapour Deposition diamond detector is in development. The synthetic diamond is used as a UV detector to image nucleic acids in electrophoresis gels. The microstrip diamond detector currently has a spatial resolution of 30 μm. Preliminary results are presented which include: QE measurements of diamond detectors, detector time response, detector UV response and current detection limits of biomolecules in gel. The potential applications of the technology, and its significant advantages in speed and sensitivity over the current systems are discussed

Simulation of image detectors in radiology for determination of scatter-to-primary ratios using Monte Carlo radiation transport code MCNP/MCNPX.

Science.gov (United States)

Smans, Kristien; Zoetelief, Johannes; Verbrugge, Beatrijs; Haeck, Wim; Struelens, Lara; Vanhavere, Filip; Bosmans, Hilde

2010-05-01

The purpose of this study was to compare and validate three methods to simulate radiographic image detectors with the Monte Carlo software MCNP/MCNPX in a time efficient way. The first detector model was the standard semideterministic radiography tally, which has been used in previous image simulation studies. Next to the radiography tally two alternative stochastic detector models were developed: A perfect energy integrating detector and a detector based on the energy absorbed in the detector material. Validation of three image detector models was performed by comparing calculated scatter-to-primary ratios (SPRs) with the published and experimentally acquired SPR values. For mammographic applications, SPRs computed with the radiography tally were up to 44% larger than the published results, while the SPRs computed with the perfect energy integrating detectors and the blur-free absorbed energy detector model were, on the average, 0.3% (ranging from -3% to 3%) and 0.4% (ranging from -5% to 5%) lower, respectively. For general radiography applications, the radiography tally overestimated the measured SPR by as much as 46%. The SPRs calculated with the perfect energy integrating detectors were, on the average, 4.7% (ranging from -5.3% to -4%) lower than the measured SPRs, whereas for the blur-free absorbed energy detector model, the calculated SPRs were, on the average, 1.3% (ranging from -0.1% to 2.4%) larger than the measured SPRs. For mammographic applications, both the perfect energy integrating detector model and the blur-free energy absorbing detector model can be used to simulate image detectors, whereas for conventional x-ray imaging using higher energies, the blur-free energy absorbing detector model is the most appropriate image detector model. The radiography tally overestimates the scattered part and should therefore not be used to simulate radiographic image detectors.

Low energy electron microscopy imaging using Medipix2 detector

International Nuclear Information System (INIS)

Sikharulidze, I.; Gastel, R. van; Schramm, S.; Abrahams, J.P.; Poelsema, B.; Tromp, R.M.; Molen, S.J. van der

2011-01-01

Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

Low energy electron microscopy imaging using Medipix2 detector

Energy Technology Data Exchange (ETDEWEB)

Sikharulidze, I., E-mail: irakli@chem.leidenuniv.nl [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Gastel, R. van [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Schramm, S. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); Abrahams, J.P. [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Poelsema, B. [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Tromp, R.M. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Molen, S.J. van der [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands)

2011-05-15

Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

A Thermal Imaging Instrument with Uncooled Detectors

Data.gov (United States)

National Aeronautics and Space Administration — In this proposed work, we will perform an instrument concept study for sustainable thermal imaging over land with uncooled detectors. We will define the science and...

FPGA-Based Flexible Hardware Architecture for Image Interest Point Detection

Directory of Open Access Journals (Sweden)

Ana Hernandez-Lopez

2015-07-01

Full Text Available An important challenge in computer vision is the implementation of fast and accurate feature detectors, as they are the basis for high-level image processing analysis and understanding. However, image feature detectors cannot be easily applied in embedded scenarios, mainly due to the fact that they are time consuming and require a significant amount of processing power. Although some feature detectors have been implemented in hardware, most implementations target a single detector under very specific constraints. This paper proposes a flexible hardware implementation approach for computing interest point extraction from grey-level images based on two different detectors, Harris and SUSAN, suitable for robotic applications. The design is based on parallel and configurable processing elements for window operators and a buffering strategy to support a coarse-grain pipeline scheme for operator sequencing. When targeted to a Virtex-6 FPGA, a throughput of 49.45 Mpixel/s (processing rate of 161 frames per second of VGA image resolution is achieved at a clock frequency of 50 MHz.

Detector design issues for compact nuclear emission cameras dedicated to breast imaging

International Nuclear Information System (INIS)

Levin, Craig S.

2003-01-01

Certain gamma ray and positron emitting radiotracers have shown great promise for use in the detection, diagnosis and staging of breast cancer. Unfortunately, standard nuclear emission cameras (SPECT, PET) found in the clinic are not practical for breast imaging of these emissions due to inadequate spatial and energy resolutions and sensitivity, large and awkward size, and relatively high cost per study. High spatial and energy resolutions and sensitivity are needed for good lesion detectability. Due to these limitations of standard cameras, there has been recent research into the development of small, compact nuclear emission imagers dedicated for close-proximity breast imaging. The small detector head size means a variety of exotic detectors or collimators may be implemented to improve spatial and energy resolution and sensitivity performances at a reasonable cost. In this paper, we will present some of the compact gamma ray and annihilation photon imaging detector designs that have been proposed and/or developed for dedicated breast imaging. We will review the physics and discuss the advantages and disadvantages of various detector configurations. Finally we will estimate the fundamental spatial resolution potential available with close-proximity nuclear emission imaging and discuss how one may approach those limits through proper detector design

High resolution X radiography imaging detector-micro gap chamber

International Nuclear Information System (INIS)

Long Huqiang; Wang Yun; Xu Dong; Xie Kuanzhong; Bian Jianjiang

2007-01-01

Micro gap chamber (MGC) is a new type of Two-Dimensional position sensitive detector having excellent properties on the space and time resolution, counting rate, 2D compact structure and the flexible of application. It will become a candidate of a new tracking detector for high energy physics experiment. The basic structure and properties of MGC as well as its main research subjects are presented in this paper. Furthermore, the feasibility and validity of utilizing diamond films as the MGC gap material were also discussed in detail. So, a potential radiography imaging detector is provided in order to realize X image and X ray diffraction experiment having very good spatial and time resolution in the 3rd Generation of Synchrotron Radiation Facility. (authors)

Detector response restoration in image reconstruction of high resolution positron emission tomography

International Nuclear Information System (INIS)

Liang, Z.

1994-01-01

A mathematical method was studied to model the detector response of high spatial-resolution positron emission tomography systems consisting of close-packed small crystals, and to restore the resolution deteriorated due to crystal penetration and/or nonuniform sampling across the field-of-view (FOV). The simulated detector system had 600 bismuth germanate crystals of 3.14 mm width and 30 mm length packed on a single ring of 60 cm diameter. The space between crystal was filled up with lead. Each crystal was in coincidence with 200 opposite crystals so that the FOV had a radius of 30 cm. The detector response was modeled based on the attenuating properties of the crystals and the septa, as well as the geometry of the detector system. The modeled detector-response function was used to restore the projections from the sinogram of the ring-detector system. The restored projections had a uniform sampling of 1.57 mm across the FOV. The crystal penetration and/or the nonuniform sampling were compensated in the projections. A penalized maximum-likelihood algorithm was employed to accomplish the restoration. The restored projections were then filtered and backprojected to reconstruct the image. A chest phantom with a few small circular ''cold'' objects located at the center and near the periphery of FOV was computer generated and used to test the restoration. The reconstructed images from the restored projections demonstrated resolution improvement off the FOV center, while preserving the resolution near the center

Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam

Science.gov (United States)

Silva, A. L. M.; Figueroa, R.; Jaramillo, A.; Carvalho, M. L.; Veloso, J. F. C. A.

2013-08-01

Energy dispersive X-ray fluorescence (EDXRF) imaging systems are of great interest in many applications of different areas, once they allow us to get images of the spatial elemental distribution in the samples. The detector system used in this study is based on a micro patterned gas detector, named Micro-Hole and Strip Plate. The full field of view system, with an active area of 28 × 28 mm2 presents some important features for EDXRF imaging applications, such as a position resolution below 125 μm, an intrinsic energy resolution of about 14% full width at half maximum for 5.9 keV X-rays, and a counting rate capability of 0.5 MHz. In this work, analysis of human teeth treated by dental amalgam was performed by using the EDXRF imaging system mentioned above. The goal of the analysis is to evaluate the system capabilities in the biomedical field by measuring the drift of the major constituents of a dental amalgam, Zn and Hg, throughout the tooth structures. The elemental distribution pattern of these elements obtained during the analysis suggests diffusion of these elements from the amalgam to teeth tissues.

The Edge Detectors Suitable for Retinal OCT Image Segmentation

Directory of Open Access Journals (Sweden)

Su Luo

2017-01-01

Full Text Available Retinal layer thickness measurement offers important information for reliable diagnosis of retinal diseases and for the evaluation of disease development and medical treatment responses. This task critically depends on the accurate edge detection of the retinal layers in OCT images. Here, we intended to search for the most suitable edge detectors for the retinal OCT image segmentation task. The three most promising edge detection algorithms were identified in the related literature: Canny edge detector, the two-pass method, and the EdgeFlow technique. The quantitative evaluation results show that the two-pass method outperforms consistently the Canny detector and the EdgeFlow technique in delineating the retinal layer boundaries in the OCT images. In addition, the mean localization deviation metrics show that the two-pass method caused the smallest edge shifting problem. These findings suggest that the two-pass method is the best among the three algorithms for detecting retinal layer boundaries. The overall better performance of Canny and two-pass methods over EdgeFlow technique implies that the OCT images contain more intensity gradient information than texture changes along the retinal layer boundaries. The results will guide our future efforts in the quantitative analysis of retinal OCT images for the effective use of OCT technologies in the field of ophthalmology.

A Ring Imaging Cerenkov detector for the CERN OMEGA spectrometer

International Nuclear Information System (INIS)

Apsimon, R.J.; Cowell, J.; Flower, P.S.

1984-12-01

A large acceptance Ring Imaging Cerenkov detector has been constructed for use at the CERN Omega Spectrometer. The design of the detector is discussed, with attention paid to its principal components, and preliminary results are given which show that the detector is capable of identifying pions and protons at 100 GeV/c. (author)

Imaging plate, a new type of x-ray area detector

International Nuclear Information System (INIS)

Kamiya, Nobuo; Amemiya, Yoshiyuki; Miyahara, Junji.

1986-01-01

In respective fields of X-ray crystallography, for the purpose of the efficient collection of reciprocal space information, two-dimensional X-ray detectors such as multiwire proportional chambers and X-ray television sets have been used together with conventional X-ray films. X-ray films are characterized by uniform sensitivity and high positional resolution over a wide area, but the sensitivity is low, and the range of action and the linearity of the sensitivity is problematic. They require the development process, accordingly lack promptitude. The MWPCs and X-ray television sets are superior in the sensitivity, its linearity, the range of action and promptitude, but interior in the uniformity and resolution to the films. Imaging plate is a new X-ray area detector developed by Fuji Photo Film Co., Ltd., for digital X-ray medical image diagnosis. This detector is superior in all the above mentioned performances, and it seems very useful also for X-ray crystallography. In this paper, the system composed of an imaging plate and its reader is described, and the basic performance as an X-ray area detector and the results of having recorded the diffraction images of protein crystals as the example of applying it to X-ray crystallography are reported. The imaging plate is that the crystalline fluorescent powder of BaFBr doped with Eu 2+ ions is applied on plastic films. (Kako, I.)

Development of a reader for track etch detectors based on a commercially available slide scanner

CERN Document Server

Steele, J D; Tanner, R J; Bartlett, D T

1999-01-01

NRPB has operated a routine neutron personal dosimetry service based on the electrochemical etch of PADC elements since 1986. Since its inception it has used an automated reader based on a video camera and real time analysis. A new and more powerful replacement system has been developed using a commercially available photographic slide scanner. This permits a complete image of the dosemeter to be grabbed in a single scan, generating a 2592x3888 pixel file which is saved for subsequent analysis. This gives an effective pixel size of 10x10 mu m with an image of the entire dosemeter in one field of view. Custom written software subsequently analyses the image to assess the number of etched pits on the dosemeter and read the detector identification number (code). Batch scanning of up to 40 detectors is also possible using an autofeed attachment. The system can be used for electrochemically etched tracks for neutron detectors and chemically etched tracks for radon detectors.

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector

Energy Technology Data Exchange (ETDEWEB)

Giewekemeyer, Klaus, E-mail: klaus.giewekemeyer@xfel.eu [European XFEL GmbH, Hamburg (Germany); Philipp, Hugh T. [Cornell University, Ithaca, NY (United States); Wilke, Robin N. [Georg-August-Universität Göttingen, Göttingen (Germany); Aquila, Andrew [European XFEL GmbH, Hamburg (Germany); Osterhoff, Markus [Georg-August-Universität Göttingen, Göttingen (Germany); Tate, Mark W.; Shanks, Katherine S. [Cornell University, Ithaca, NY (United States); Zozulya, Alexey V. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Salditt, Tim [Georg-August-Universität Göttingen, Göttingen (Germany); Gruner, Sol M. [Cornell University, Ithaca, NY (United States); Cornell University, Ithaca, NY (United States); Kavli Institute of Cornell for Nanoscience, Ithaca, NY (United States); Mancuso, Adrian P. [European XFEL GmbH, Hamburg (Germany)

2014-08-07

The advantages of a novel wide dynamic range hard X-ray detector are demonstrated for (ptychographic) coherent X-ray diffractive imaging. Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 10{sup 8} 8-keV photons pixel{sup −1} s{sup −1}, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 10{sup 10} photons µm{sup −2} s{sup −1} within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while ‘still’ images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described.

A ring image Cerenkov detector for the CERN Omega Spectrometer

International Nuclear Information System (INIS)

Davenport, M.; Deol, R.S.; Flower, P.S.

1983-05-01

A development program has been undertaken to produce a large ring image Cerenkov detector (RICH) for use at the CERN Omega Spectrometer. A prototype Cerenkov counter has been constructed and successfully operated in a high energy particle beam, Cerenkov rings having been observed in an experimental time projection chamber (TPC) using the photoionising agents Triethylamine (TEA) and Tetrakis (dimethylamine) ethylene (TMAE). Systematic measurements have been made of the optical properties of window materials and reflecting surfaces in the vacuum ultraviolet region. Results of these tests are presented, and the design of the large detector based on these experiences together with Monte Carlo simulations of the events expected in the WA69 experiment, is discussed. (author)

Properties of GaAs:Cr-based Timepix detectors

Science.gov (United States)

Smolyanskiy, P.; Bergmann, B.; Chelkov, G.; Kotov, S.; Kruchonak, U.; Kozhevnikov, D.; Mora Sierra, Y.; Stekl, I.; Zhemchugov, A.

2018-02-01

The hybrid pixel detector technology brought to the X-ray imaging a low noise level at a high spatial resolution, thanks to the single photon counting. However, silicon as the most widespread detector material is marginally sensitive to photons with energies above 30 keV. Therefore, the high-Z alternatives to silicon such as gallium arsenide and cadmium telluride are increasingly attracting attention of the community for the development of X-ray imaging systems. The results of our investigations of the Timepix detectors bump bonded to sensors made of gallium arsenide compensated by chromium (GaAs:Cr) are presented in this work. The following properties are most important from the practical point of view: the IV characteristics, the charge transport characteristics, photon detection efficiency, operational stability, homogeneity, temperature dependence, as well as energy and spatial resolution are considered. The applicability of these detectors for spectroscopic X-ray imaging is discussed.

High spatial resolution gamma imaging detector based on a 5 inch diameter R3292 Hamamatsu PSPMT

International Nuclear Information System (INIS)

Wojcik, R.; Majewski, S.; Kross, B.; Weisenberger, A.G.; Steinbach, D.

1998-01-01

High resolution imaging gamma-ray detectors were developed using Hamamatsu's 5 inch diameter R3292 position sensitive PMT (PSPMT) and a variety of crystal scintillator arrays. Special readout techniques were used to maximize the active imaging area while reducing the number of readout channels. Spatial resolutions approaching 1 mm were obtained in a broad energy range from 20 to 511 keV. Results are also presented of coupling the scintillator arrays to the PMT via imaging light guides consisting of acrylic optical fibers

Energy dispersive detector for white beam synchrotron x-ray fluorescence imaging

Energy Technology Data Exchange (ETDEWEB)

Wilson, Matthew D., E-mail: Matt.Wilson@stfc.ac.uk; Seller, Paul; Veale, Matthew C. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus,UK (United Kingdom); Connolley, Thomas [Diamond Light Source, I12 Beamline, Harwell Campus, Didcot, Oxfordshire (United Kingdom); Dolbnya, Igor P.; Malandain, Andrew; Sawhney, Kawal [Diamond Light Source, B16 Beamline, Harwell Campus, Didcot, Oxfordshire (United Kingdom); Grant, Patrick S.; Liotti, Enzo; Lui, Andrew [Department of Materials, University of Oxford Parks Road, Oxford (United Kingdom)

2016-07-27

A novel, “single-shot” fluorescence imaging technique has been demonstrated on the B16 beamline at the Diamond Light Source synchrotron using the HEXITEC energy dispersive imaging detector. A custom made furnace with 200µm thick metal alloy samples was positioned in a white X-ray beam with a hole made in the furnace walls to allow the transmitted beam to be imaged with a conventional X-ray imaging camera consisting of a 500 µm thick single crystal LYSO scintillator, mirror and lens coupled to an AVT Manta G125B CCD sensor. The samples were positioned 45° to the incident beam to enable simultaneous transmission and fluorescence imaging. The HEXITEC detector was positioned at 90° to the sample with a 50 µm pinhole 13 cm from the sample and the detector positioned 2.3m from pinhole. The geometric magnification provided a field of view of 1.1×1.1mm{sup 2} with one of the 80×80 pixels imaging an area equivalent to 13µm{sup 2}. Al-Cu alloys doped with Zr, Ag and Mo were imaged in transmission and fluorescence mode. The fluorescence images showed that the dopant metals could be simultaneously imaged with sufficient counts on all 80x80 pixels within 60 s, with the X-ray flux limiting the fluorescence imaging rate. This technique demonstrated that it is possible to simultaneously image and identify multiple elements on a spatial resolution scale ~10µm or higher without the time consuming need to scan monochromatic energies or raster scan a focused beam of X-rays. Moving to high flux beamlines and using an array of detectors could improve the imaging speed of the technique with element specific imaging estimated to be on a 1 s timescale.

Energy dispersive detector for white beam synchrotron x-ray fluorescence imaging

International Nuclear Information System (INIS)

Wilson, Matthew D.; Seller, Paul; Veale, Matthew C.; Connolley, Thomas; Dolbnya, Igor P.; Malandain, Andrew; Sawhney, Kawal; Grant, Patrick S.; Liotti, Enzo; Lui, Andrew

2016-01-01

A novel, “single-shot” fluorescence imaging technique has been demonstrated on the B16 beamline at the Diamond Light Source synchrotron using the HEXITEC energy dispersive imaging detector. A custom made furnace with 200µm thick metal alloy samples was positioned in a white X-ray beam with a hole made in the furnace walls to allow the transmitted beam to be imaged with a conventional X-ray imaging camera consisting of a 500 µm thick single crystal LYSO scintillator, mirror and lens coupled to an AVT Manta G125B CCD sensor. The samples were positioned 45° to the incident beam to enable simultaneous transmission and fluorescence imaging. The HEXITEC detector was positioned at 90° to the sample with a 50 µm pinhole 13 cm from the sample and the detector positioned 2.3m from pinhole. The geometric magnification provided a field of view of 1.1×1.1mm"2 with one of the 80×80 pixels imaging an area equivalent to 13µm"2. Al-Cu alloys doped with Zr, Ag and Mo were imaged in transmission and fluorescence mode. The fluorescence images showed that the dopant metals could be simultaneously imaged with sufficient counts on all 80x80 pixels within 60 s, with the X-ray flux limiting the fluorescence imaging rate. This technique demonstrated that it is possible to simultaneously image and identify multiple elements on a spatial resolution scale ~10µm or higher without the time consuming need to scan monochromatic energies or raster scan a focused beam of X-rays. Moving to high flux beamlines and using an array of detectors could improve the imaging speed of the technique with element specific imaging estimated to be on a 1 s timescale.

LISe pixel detector for neutron imaging

Energy Technology Data Exchange (ETDEWEB)

Herrera, Elan; Hamm, Daniel [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Wiggins, Brenden [Technology Development, Y-12 National Security Complex, Oak Ridge, TN (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Milburn, Rob [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Burger, Arnold [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Department of Life and Physical Sciences, Fisk University, Nashville, TN (United States); Bilheux, Hassina [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Santodonato, Louis [Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Chvala, Ondrej [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Stowe, Ashley [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States); Technology Development, Y-12 National Security Complex, Oak Ridge, TN (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, TN (United States); Lukosi, Eric, E-mail: elukosi@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN (United States)

2016-10-11

Semiconducting lithium indium diselenide, {sup 6}LiInSe{sub 2} or LISe, has promising characteristics for neutron detection applications. The 95% isotopic enrichment of {sup 6}Li results in a highly efficient thermal neutron-sensitive material. In this study, we report on a proof-of-principle investigation of a semiconducting LISe pixel detector to demonstrate its potential as an efficient neutron imager. The LISe pixel detector had a 4×4 of pixels with a 550 µm pitch on a 5×5×0.56 mm{sup 3} LISe substrate. An experimentally verified spatial resolution of 300 µm was observed utilizing a super-sampling technique.

Comparison of radiation dose estimates, image noise, and scan duration in pediatric body imaging for volumetric and helical modes on 320-detector CT and helical mode on 64-detector CT

International Nuclear Information System (INIS)

Johnston, Jennifer H.; Podberesky, Daniel J.; Larson, David B.; Alsip, Christopher; Yoshizumi, Terry T.; Angel, Erin; Barelli, Alessandra; Toncheva, Greta; Egelhoff, John C.; Anderson-Evans, Colin; Nguyen, Giao B.; Frush, Donald P.; Salisbury, Shelia R.

2013-01-01

Advanced multidetector CT systems facilitate volumetric image acquisition, which offers theoretic dose savings over helical acquisition with shorter scan times. Compare effective dose (ED), scan duration and image noise using 320- and 64-detector CT scanners in various acquisition modes for clinical chest, abdomen and pelvis protocols. ED and scan durations were determined for 64-detector helical, 160-detector helical and volume modes under chest, abdomen and pelvis protocols on 320-detector CT with adaptive collimation and 64-detector helical mode on 64-detector CT without adaptive collimation in a phantom representing a 5-year-old child. Noise was measured as standard deviation of Hounsfield units. Compared to 64-detector helical CT, all acquisition modes on 320-detector CT resulted in lower ED and scan durations. Dose savings were greater for chest (27-46%) than abdomen/pelvis (18-28%) and chest/abdomen/pelvis imaging (8-14%). Noise was similar across scanning modes, although some protocols on 320-detector CT produced slightly higher noise. Dose savings can be achieved for chest, abdomen/pelvis and chest/abdomen/pelvis examinations on 320-detector CT compared to helical acquisition on 64-detector CT, with shorter scan durations. Although noise differences between some modes reached statistical significance, this is of doubtful diagnostic significance and will be studied further in a clinical setting. (orig.)

Modelling of scintillator based flat-panel detectors with Monte-Carlo simulations

International Nuclear Information System (INIS)

Reims, N; Sukowski, F; Uhlmann, N

2011-01-01

Scintillator based flat panel detectors are state of the art in the field of industrial X-ray imaging applications. Choosing the proper system and setup parameters for the vast range of different applications can be a time consuming task, especially when developing new detector systems. Since the system behaviour cannot always be foreseen easily, Monte-Carlo (MC) simulations are keys to gain further knowledge of system components and their behaviour for different imaging conditions. In this work we used two Monte-Carlo based models to examine an indirect converting flat panel detector, specifically the Hamamatsu C9312SK. We focused on the signal generation in the scintillation layer and its influence on the spatial resolution of the whole system. The models differ significantly in their level of complexity. The first model gives a global description of the detector based on different parameters characterizing the spatial resolution. With relatively small effort a simulation model can be developed which equates the real detector regarding signal transfer. The second model allows a more detailed insight of the system. It is based on the well established cascade theory, i.e. describing the detector as a cascade of elemental gain and scattering stages, which represent the built in components and their signal transfer behaviour. In comparison to the first model the influence of single components especially the important light spread behaviour in the scintillator can be analysed in a more differentiated way. Although the implementation of the second model is more time consuming both models have in common that a relatively small amount of system manufacturer parameters are needed. The results of both models were in good agreement with the measured parameters of the real system.

Detection and Imaging of High-Z Materials with a Muon Tomography Station Using GEM Detectors

CERN Document Server

Gnanvo, K; Bittner, W; Costa, F; Grasso, L; Hohlmann, M; Locke, J B; Martoiu, S; Muller, H; Staib, M; Tarazona, A; Toledo, J

2010-01-01

Muon tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons is a promising technique for detecting and imaging heavily shielded high-Z nuclear materials such as enriched uranium. This technique could complement standard radiation detection portals currently deployed at international borders and ports, which are not very sensitive to heavily shielded nuclear materials. We image small targets in 3D using $2\\times 2 \\times 2$ mm^3 voxels with a minimal muon tomography station prototype that tracks muons with Gas Electron Multiplier (GEM) detectors read out in 2D with x-y microstrips of 400 micron pitch. With preliminary electronics, the GEM detectors achieve a spatial resolution of 130 microns in both dimensions. With the next GEM-based prototype station we plan to probe an active volume of ~27 liters. We present first results on reading out all 1536 microstrips of a $30 \\times 30$ cm^2 GEM detector for the next muon tomography prototype with final frontend electronics and DAQ...

Investigation of photon counting pixel detectors for X-ray spectroscopy and imaging

Energy Technology Data Exchange (ETDEWEB)

Talla, Patrick Takoukam

2011-04-07

The Medipix2 and Medipix3 detectors are hybrid pixelated photon counting detectors with a pixel pitch of 55 {mu}m. The sensor material used in this thesis was silicon. Because of their small pixel size they suffer from charge sharing i.e. an incoming photon can be registered by more than one pixel. In order to correct for charge sharing due to lateral diffusion of charge carriers, the Medipix3 detector was developed: with its Charge Summing Mode, the charge collected in a cluster of 2 x 2 pixel is added up and attributed to only one pixel whose counter is incremented. The adjustable threshold of the detectors allows to count the photons and to gain information on their energy. The main purposes of the thesis are to investigate spectral and imaging properties of pixelated photon counting detectors from the Medipix family such as Medipix2 and Medipix3. The investigations are based on simulations and measurements. In order to investigate the spectral properties of the detectors measurements were performed using fluorescence lines of materials such as molybdenum, silver but also some radioactive sources such as Am-241 or Cd-109. From the measured data, parameters like the threshold dispersion and the gain variation from pixel-to-pixel were extracted and used as input in the Monte Carlo code ROSI to model the responses of the detector to monoenergetic photons. The measured data are well described by the simulations for Medipix2 and for Medipix3 operating in Charge Summing Mode. Due to charge sharing and due to the energy dependence of attenuation processes in silicon and to Compton scattering the incoming and the measured spectrum differ substantially from each other. Since the responses to monoenergetic photons are known, a deconvolution was performed to determine the true incoming spectrum. Several direct and iterative methods were successfully applied on measured and simulated data of an X-ray tube and radioactive sources. The knowledge of the X-ray spectrum is

Investigation of photon counting pixel detectors for X-ray spectroscopy and imaging

International Nuclear Information System (INIS)

Talla, Patrick Takoukam

2011-01-01

The Medipix2 and Medipix3 detectors are hybrid pixelated photon counting detectors with a pixel pitch of 55 μm. The sensor material used in this thesis was silicon. Because of their small pixel size they suffer from charge sharing i.e. an incoming photon can be registered by more than one pixel. In order to correct for charge sharing due to lateral diffusion of charge carriers, the Medipix3 detector was developed: with its Charge Summing Mode, the charge collected in a cluster of 2 x 2 pixel is added up and attributed to only one pixel whose counter is incremented. The adjustable threshold of the detectors allows to count the photons and to gain information on their energy. The main purposes of the thesis are to investigate spectral and imaging properties of pixelated photon counting detectors from the Medipix family such as Medipix2 and Medipix3. The investigations are based on simulations and measurements. In order to investigate the spectral properties of the detectors measurements were performed using fluorescence lines of materials such as molybdenum, silver but also some radioactive sources such as Am-241 or Cd-109. From the measured data, parameters like the threshold dispersion and the gain variation from pixel-to-pixel were extracted and used as input in the Monte Carlo code ROSI to model the responses of the detector to monoenergetic photons. The measured data are well described by the simulations for Medipix2 and for Medipix3 operating in Charge Summing Mode. Due to charge sharing and due to the energy dependence of attenuation processes in silicon and to Compton scattering the incoming and the measured spectrum differ substantially from each other. Since the responses to monoenergetic photons are known, a deconvolution was performed to determine the true incoming spectrum. Several direct and iterative methods were successfully applied on measured and simulated data of an X-ray tube and radioactive sources. The knowledge of the X-ray spectrum is

Compton imaging with a highly-segmented, position-sensitive HPGe detector

Energy Technology Data Exchange (ETDEWEB)

Steinbach, T.; Hirsch, R.; Reiter, P.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Hess, H.; Lewandowski, L. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Gernhaeuser, R.; Maier, L.; Schlarb, M.; Weiler, B.; Winkel, M. [Technische Universitaet Muenchen, Physik Department, Garching (Germany)

2017-02-15

A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8 {sup circle} and 19.1 {sup circle}, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6 {sup circle} was determined for the same γ-ray energy. (orig.)

EUV high resolution imager on-board solar orbiter: optical design and detector performances

Science.gov (United States)

Halain, J. P.; Mazzoli, A.; Rochus, P.; Renotte, E.; Stockman, Y.; Berghmans, D.; BenMoussa, A.; Auchère, F.

2017-11-01

The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric layers at 17.4 nm wavelength with a 200 km resolution. The HRI channel is based on a compact two mirrors off-axis design. The spectral selection is obtained by a multilayer coating deposited on the mirrors and by redundant Aluminum filters rejecting the visible and infrared light. The detector is a 2k x 2k array back-thinned silicon CMOS-APS with 10 μm pixel pitch, sensitive in the EUV wavelength range. Due to the instrument compactness and the constraints on the optical design, the channel performance is very sensitive to the manufacturing, alignments and settling errors. A trade-off between two optical layouts was therefore performed to select the final optical design and to improve the mirror mounts. The effect of diffraction by the filter mesh support and by the mirror diffusion has been included in the overall error budget. Manufacturing of mirror and mounts has started and will result in thermo-mechanical validation on the EUI instrument structural and thermal model (STM). Because of the limited channel entrance aperture and consequently the low input flux, the channel performance also relies on the detector EUV sensitivity, readout noise and dynamic range. Based on the characterization of a CMOS-APS back-side detector prototype, showing promising results, the EUI detector has been specified and is under development. These detectors will undergo a qualification program before being tested and integrated on the EUI instrument.

Rapid portal imaging with a high-efficiency, large field-of-view detector.

Science.gov (United States)

Mosleh-Shirazi, M A; Evans, P M; Swindell, W; Symonds-Tayler, J R; Webb, S; Partridge, M

1998-12-01

The design, construction, and performance evaluation of an electronic portal imaging device (EPID) are described. The EPID has the same imaging geometry as the current mirror-based systems except for the x-ray detection stage, where a two-dimensional (2D) array of 1 cm thick CsI(Tl) detector elements are utilized. The approximately 18% x-ray quantum efficiency of the scintillation detector and its 30 x 40 cm2 field-of-view at the isocenter are greater than other area-imaging EPIDs. The imaging issues addressed are theoretical and measured signal-to-noise ratio, linearity of the imaging chain, influence of frame-summing on image quality and image calibration. Portal images of test objects and a humanoid phantom are used to measure the performance of the system. An image quality similar to the current devices is achieved but with a lower dose. With approximately 1 cGy dose delivered by a 6 MV beam, a 2 mm diam structure of 1.3% contrast and an 18 mm diam object of 0.125% contrast can be resolved without using image-enhancement methods. A spatial resolution of about 2 mm at the isocenter is demonstrated. The capability of the system to perform fast sequential imaging, synchronized with the radiation pulses, makes it suitable for patient motion studies and verification of intensity-modulated beams as well as its application in cone-beam megavoltage computed tomography.

Active terahertz imaging with Ne indicator lamp detector arrays

Science.gov (United States)

Kopeika, N. S.; Abramovich, A.; Yadid-Pecht, O.; Yitzhaky, Y.

2009-08-01

The advantages of terahertz (THz) imaging are well known. They penetrate well most non-conducting media and there are no known biological hazards, This makes such imaging systems important for homeland security, as they can be used to image concealed objects and often into rooms or buildings from the outside. There are also biomedical applications that are arising. Unfortunately, THz imaging is quite expensive, especially for real time systems, largely because of the price of the detector. Bolometers and pyroelectric detectors can each easily cost at least hundreds of dollars if not more, thus making focal plane arrays of them quite expensive. We have found that common miniature commercial neon indicator lamps costing typically about 30 cents each exhibit high sensitivity to THz radiation [1-3], with microsecond order rise times, thus making them excellent candidates for such focal plane arrays. NEP is on the order of 10-10 W/Hz1/2. Significant improvement of detection performance is expected when heterodyne detection is used Efforts are being made to develop focal plane array imagers using such devices at 300 GHz. Indeed, preliminary images using 4x4 arrays have already been obtained. An 8x8 VLSI board has been developed and is presently being tested. Since no similar imaging systems have been developed previously, there are many new problems to be solved with such a novel and unconventional imaging system. These devices act as square law detectors, with detected signal proportional to THz power. This allows them to act as mixers in heterodyne detection, thus allowing NEP to be reduced further by almost two orders of magnitude. Plans are to expand the arrays to larger sizes, and to employ super resolution techniques to improve image quality beyond that ordinarily obtainable at THz frequencies.

Iterative image reconstruction for positron emission tomography based on a detector response function estimated from point source measurements

International Nuclear Information System (INIS)

Tohme, Michel S; Qi Jinyi

2009-01-01

The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of a sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can easily be applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3 x 3 line phantom, an ultra-micro resolution phantom and a 22 Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

Simulation of scintillating fiber gamma ray detectors for medical imaging

International Nuclear Information System (INIS)

Chaney, R.C.; Fenyves, E.J.; Antich, P.P.

1990-01-01

This paper reports on plastic scintillating fibers which have been shown to be effective for high spatial and time resolution of gamma rays. They may be expected to significantly improve the resolution of current medical imaging systems such as PET and SPECT. Monte Carlo simulation of imaging systems using these detectors, provides a means to optimize their performance in this application, as well as demonstrate their resolution and efficiency. Monte Carlo results are presented for PET and SPECT systems constructed using these detectors

Ion-ion coincidence imaging at high event rate using an in-vacuum pixel detector

Science.gov (United States)

Long, Jingming; Furch, Federico J.; Durá, Judith; Tremsin, Anton S.; Vallerga, John; Schulz, Claus Peter; Rouzée, Arnaud; Vrakking, Marc J. J.

2017-07-01

A new ion-ion coincidence imaging spectrometer based on a pixelated complementary metal-oxide-semiconductor detector has been developed for the investigation of molecular ionization and fragmentation processes in strong laser fields. Used as a part of a velocity map imaging spectrometer, the detection system is comprised of a set of microchannel plates and a Timepix detector. A fast time-to-digital converter (TDC) is used to enhance the ion time-of-flight resolution by correlating timestamps registered separately by the Timepix detector and the TDC. In addition, sub-pixel spatial resolution (principle experiment on strong field dissociative double ionization of carbon dioxide molecules (CO2), using a 400 kHz repetition rate laser system. The experimental results demonstrate that the spectrometer can detect multiple ions in coincidence, making it a valuable tool for studying the fragmentation dynamics of molecules in strong laser fields.

Coded aperture detector: an image sensor with sub 20-nm pixel resolution.

Science.gov (United States)

Miyakawa, Ryan; Mayer, Rafael; Wojdyla, Antoine; Vannier, Nicolas; Lesser, Ian; Aron-Dine, Shifrah; Naulleau, Patrick

2014-08-11

We describe the coded aperture detector, a novel image sensor based on uniformly redundant arrays (URAs) with customizable pixel size, resolution, and operating photon energy regime. In this sensor, a coded aperture is scanned laterally at the image plane of an optical system, and the transmitted intensity is measured by a photodiode. The image intensity is then digitally reconstructed using a simple convolution. We present results from a proof-of-principle optical prototype, demonstrating high-fidelity image sensing comparable to a CCD. A 20-nm half-pitch URA fabricated by the Center for X-ray Optics (CXRO) nano-fabrication laboratory is presented that is suitable for high-resolution image sensing at EUV and soft X-ray wavelengths.

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

Science.gov (United States)

Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

2014-02-01

Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

Multi-channel imaging cytometry with a single detector

Science.gov (United States)

Locknar, Sarah; Barton, John; Entwistle, Mark; Carver, Gary; Johnson, Robert

2018-02-01

Multi-channel microscopy and multi-channel flow cytometry generate high bit data streams. Multiple channels (both spectral and spatial) are important in diagnosing diseased tissue and identifying individual cells. Omega Optical has developed techniques for mapping multiple channels into the time domain for detection by a single high gain, high bandwidth detector. This approach is based on pulsed laser excitation and a serial array of optical fibers coated with spectral reflectors such that up to 15 wavelength bins are sequentially detected by a single-element detector within 2.5 μs. Our multichannel microscopy system uses firmware running on dedicated DSP and FPGA chips to synchronize the laser, scanning mirrors, and sampling clock. The signals are digitized by an NI board into 14 bits at 60MHz - allowing for 232 by 174 pixel fields in up to 15 channels with 10x over sampling. Our multi-channel imaging cytometry design adds channels for forward scattering and back scattering to the fluorescence spectral channels. All channels are detected within the 2.5 μs - which is compatible with fast cytometry. Going forward, we plan to digitize at 16 bits with an A-toD chip attached to a custom board. Processing these digital signals in custom firmware would allow an on-board graphics processing unit to display imaging flow cytometry data over configurable scanning line lengths. The scatter channels can be used to trigger data buffering when a cell is present in the beam. This approach enables a low cost mechanically robust imaging cytometer.

Spectral detector CT-derived virtual non-contrast images: comparison of attenuation values with unenhanced CT.

Science.gov (United States)

Ananthakrishnan, Lakshmi; Rajiah, Prabhakar; Ahn, Richard; Rassouli, Negin; Xi, Yin; Soesbe, Todd C; Lewis, Matthew A; Lenkinski, Robert E; Leyendecker, John R; Abbara, Suhny

2017-03-01

To assess virtual non-contrast (VNC) images obtained on a detection-based spectral detector CT scanner and determine how attenuation on VNC images derived from various phases of enhanced CT compare to those obtained from true unenhanced images. In this HIPAA compliant, IRB approved prospective multi-institutional study, 46 patients underwent pre- and post-contrast imaging on a prototype dual-layer spectral detector CT between October 2013 and November 2015, yielding 84 unenhanced and VNC pairs (25 arterial, 39 portal venous/nephrographic, 20 urographic). Mean attenuation was measured by one of three readers in the liver, spleen, kidneys, psoas muscle, abdominal aorta, and subcutaneous fat. Equivalence testing was used to determine if the mean difference between unenhanced and VNC attenuation was less than 5, 10, or 15 HU. VNC image quality was assessed on a 5 point scale. Mean difference between unenhanced and VNC attenuation was VNC attenuation were equivalent in all tissues except fat using a threshold of VNC overestimated the HU relative to unenhanced images. VNC image quality was rated as excellent or good in 84% of arterial phase and 85% of nephrographic phase cases, but only 40% of urographic phase. VNC images derived from novel dual layer spectral detector CT demonstrate attenuation values similar to unenhanced images in all tissues evaluated except for subcutaneous fat. Further study is needed to determine if attenuation thresholds currently used clinically for common pathology should be adjusted, particularly for lesions containing fat.

Smile detectors correlation

Science.gov (United States)

Yuksel, Kivanc; Chang, Xin; Skarbek, Władysław

2017-08-01

The novel smile recognition algorithm is presented based on extraction of 68 facial salient points (fp68) using the ensemble of regression trees. The smile detector exploits the Support Vector Machine linear model. It is trained with few hundreds exemplar images by SVM algorithm working in 136 dimensional space. It is shown by the strict statistical data analysis that such geometric detector strongly depends on the geometry of mouth opening area, measured by triangulation of outer lip contour. To this goal two Bayesian detectors were developed and compared with SVM detector. The first uses the mouth area in 2D image, while the second refers to the mouth area in 3D animated face model. The 3D modeling is based on Candide-3 model and it is performed in real time along with three smile detectors and statistics estimators. The mouth area/Bayesian detectors exhibit high correlation with fp68/SVM detector in a range [0:8; 1:0], depending mainly on light conditions and individual features with advantage of 3D technique, especially in hard light conditions.

Multiline digital radiographic imager study with synchronization to detector gas ion drift

International Nuclear Information System (INIS)

Peyret, O.

1985-01-01

This direct digital radiographic imager is based on X-ray detection in high pressure rare gas ionization chamber. This linear multidetector, from which scanning radiography is realized, records many lines together. Spatial resolution performance in scanning direction are made sure by scanning synchronization with ion drift in detector. After a physical study and a potential evaluation of its performances on mock-up, a 128 cell prototype has been realized. The first images give validation and limits of such a radiographic process [fr

Modeling the impact of preflushing on CTE in proton irradiated CCD-based detectors

Science.gov (United States)

Philbrick, R. H.

2002-04-01

A software model is described that performs a "real world" simulation of the operation of several types of charge-coupled device (CCD)-based detectors in order to accurately predict the impact that high-energy proton radiation has on image distortion and modulation transfer function (MTF). The model was written primarily to predict the effectiveness of vertical preflushing on the custom full frame CCD-based detectors intended for use on the proposed Kepler Discovery mission, but it is capable of simulating many other types of CCD detectors and operating modes as well. The model keeps track of the occupancy of all phosphorous-silicon (P-V), divacancy (V-V) and oxygen-silicon (O-V) defect centers under every CCD electrode over the entire detector area. The integrated image is read out by simulating every electrode-to-electrode charge transfer in both the vertical and horizontal CCD registers. A signal level dependency on the capture and emission of signal is included and the current state of each electrode (e.g., barrier or storage) is considered when distributing integrated and emitted signal. Options for performing preflushing, preflashing, and including mini-channels are available on both the vertical and horizontal CCD registers. In addition, dark signal generation and image transfer smear can be selectively enabled or disabled. A comparison of the charge transfer efficiency (CTE) data measured on the Hubble space telescope imaging spectrometer (STIS) CCD with the CTE extracted from model simulations of the STIS CCD show good agreement.

A new design of the gaseous imaging detector: Micro Pixel Chamber

CERN Document Server

Ochi, A; Koishi, S; Tanimori, T; Nagae, T; Nakamura, M

2001-01-01

The novel gaseous detector 'Micro Pixel Chamber (Micro PIC)' has been developed for X-ray, gamma-ray and charged particle imaging. This detector consists of double sided printing circuit board (PCB). The stable operation of Micro PIC is realized by thick substrate and wide anode strips. One of the most outstanding feature is the process of production and the cost. The base technology of producing Micro PIC is same as producing PCB, then detector with large detection area (more than 10 cmx10 cm) can be made by present technology. Our first tests were performed using a 3 cmx3 cm detection area with a readout of 0.4 mm pitch. The gas gain and stability were measured in these tests. The gas gain of 10 sup 4 was obtained using argon ethane (8:2) gas mixture. Also, there was no discharge between anodes and cathodes in the gain of 10 sup 3 during two days of continuous operation. Although some discharges occurred in the higher gain (approximately 10 sup 4), no critical damage on the detector was found.

X-ray Imaging Using a Hybrid Photon Counting GaAs Pixel Detector

CERN Document Server

Schwarz, C; Göppert, R; Heijne, Erik H M; Ludwig, J; Meddeler, G; Mikulec, B; Pernigotti, E; Rogalla, M; Runge, K; Smith, K M; Snoeys, W; Söldner-Rembold, S; Watt, J

1999-01-01

The performance of hybrid GaAs pixel detectors as X-ray imaging sensors were investigated at room temperature. These hybrids consist of 300 mu-m thick GaAs pixel detectors, flip-chip bonded to a CMOS Single Photon Counting Chip (PCC). This chip consists of a matrix of 64 x 64 identical square pixels (170 mu-m x 170 mu-m) and covers a total area of 1.2 cm**2. The electronics in each cell comprises a preamplifier, a discriminator with a 3-bit threshold adjust and a 15-bit counter. The detector is realized by an array of Schottky diodes processed on semi-insulating LEC-GaAs bulk material. An IV-charcteristic and a detector bias voltage scan showed that the detector can be operated with voltages around 200 V. Images of various objects were taken by using a standard X-ray tube for dental diagnostics. The signal to noise ratio (SNR) was also determined. The applications of these imaging systems range from medical applications like digital mammography or dental X-ray diagnostics to non destructive material testing (...

Scintillator Based Coded-Aperture Imaging for Neutron Detection

International Nuclear Information System (INIS)

Hayes, Sean-C.; Gamage, Kelum-A-A.

2013-06-01

In this paper we are going to assess the variations of neutron images using a series of Monte Carlo simulations. We are going to study neutron images of the same neutron source with different source locations, using a scintillator based coded-aperture system. The Monte Carlo simulations have been conducted making use of the EJ-426 neutron scintillator detector. This type of detector has a low sensitivity to gamma rays and is therefore of particular use in a system with a source that emits a mixed radiation field. From the use of different source locations, several neutron images have been produced, compared both qualitatively and quantitatively for each case. This allows conclusions to be drawn on how suited the scintillator based coded-aperture neutron imaging system is to detecting various neutron source locations. This type of neutron imaging system can be easily used to identify and locate nuclear materials precisely. (authors)

Development of CRID [Cerenkov Ring Imaging Detector] single electron wire detector

International Nuclear Information System (INIS)

Aston, D.; Bean, A.; Bienz, T.

1989-02-01

We describe the R and D effort to define the design parameters, method of construction and experimental results from the single electron wire detectors. These detectors will be used for particle identification using the Cerenkov Ring Imaging techniques in the SLD experiment at SLAC. We present measurements of pulse heights for several gases as a function of gas gain, charge division performance on a single electron signal using both 7 μm and 33 μm diameter carbon wires, photon feedback in TMAE laden gas, average pulse shape, and its comparison with the predicted shape and cross-talk. In addition, we present results of wire aging tests, and other tests associated with construction of this unusual type of wire chamber. 12 refs., 9 figs

High-Resolution Gamma-Ray Imaging Measurements Using Externally Segmented Germanium Detectors

Science.gov (United States)

Callas, J.; Mahoney, W.; Skelton, R.; Varnell, L.; Wheaton, W.

1994-01-01

Fully two-dimensional gamma-ray imaging with simultaneous high-resolution spectroscopy has been demonstrated using an externally segmented germanium sensor. The system employs a single high-purity coaxial detector with its outer electrode segmented into 5 distinct charge collection regions and a lead coded aperture with a uniformly redundant array (URA) pattern. A series of one-dimensional responses was collected around 511 keV while the system was rotated in steps through 180 degrees. A non-negative, linear least-squares algorithm was then employed to reconstruct a 2-dimensional image. Corrections for multiple scattering in the detector, and the finite distance of source and detector are made in the reconstruction process.

Evaluation of XRI-UNO CdTe detector for nuclear medical imaging

International Nuclear Information System (INIS)

Jambi, L.K.; Lees, J.E.; Bugby, S.L.; Alqahtani, M.S.; Tipper, S.; Perkins, A.C.

2015-01-01

Over the last two decades advances in semiconductor detector technology have reached the point where they are sufficiently sensitive to become an alternative to scintillators for high energy gamma ray detection for application in fields such as medical imaging. This paper assessed the Cadmium-Telluride (CdTe) XRI-UNO semiconductor detector produced by X-RAY Imatek for photon energies of interest in nuclear imaging. The XRI-UNO detector was found to have an intrinsic spatial resolution of <0.5mm and a high incident count rate capability up to at least 1680cps. The system spatial resolution, uniformity and sensitivity characteristics are also reported

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

International Nuclear Information System (INIS)

Kim, Joshua; Zhang, Tiezhi; Lu, Weiguo

2014-01-01

Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source–dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10–15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source–dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented. (paper)

Quantitative SPECT brain imaging: Effects of attenuation and detector response

International Nuclear Information System (INIS)

Gilland, D.R.; Jaszczak, R.J.; Bowsher, J.E.; Turkington, T.G.; Liang, Z.; Greer, K.L.; Coleman, R.E.

1993-01-01

Two physical factors that substantially degrade quantitative accuracy in SPECT imaging of the brain are attenuation and detector response. In addition to the physical factors, random noise in the reconstructed image can greatly affect the quantitative measurement. The purpose of this work was to implement two reconstruction methods that compensate for attenuation and detector response, a 3D maximum likelihood-EM method (ML) and a filtered backprojection method (FB) with Metz filter and Chang attenuation compensation, and compare the methods in terms of quantitative accuracy and image noise. The methods were tested on simulated data of the 3D Hoffman brain phantom. The simulation incorporated attenuation and distance-dependent detector response. Bias and standard deviation of reconstructed voxel intensities were measured in the gray and white matter regions. The results with ML showed that in both the gray and white matter regions as the number of iterations increased, bias decreased and standard deviation increased. Similar results were observed with FB as the Metz filter power increased. In both regions, ML had smaller standard deviation than FB for a given bias. Reconstruction times for the ML method have been greatly reduced through efficient coding, limited source support, and by computing attenuation factors only along rays perpendicular to the detector

Preliminary test of an imaging probe for nuclear medicine using hybrid pixel detectors

International Nuclear Information System (INIS)

Bertolucci, E.; Maiorino, M.; Mettivier, G.; Montesi, M.C.; Russo, P.

2002-01-01

We are investigating the feasibility of an intraoperative imaging probe for lymphoscintigraphy with Tc-99m tracer, for sentinel node radioguided surgery, using the Medipix series of hybrid detectors coupled to a collimator. These detectors are pixelated semiconductor detectors bump-bonded to the Medipix1 photon counting read-out chip (64x64 pixel, 170 μm pitch) or to the Medipix2 chip (256x256 pixel, 55 μm pitch), developed by the European Medipix collaboration. The pixel detector we plan to use in the final version of the probe is a semi-insulating GaAs detector or a 1-2 mm thick CdZnTe detector. For the preliminary tests presented here, we used 300-μm thick silicon detectors, hybridized via bump-bonding to the Medipix1 chip. We used a tungsten parallel-hole collimator (7 mm thick, matrix array of 64x64 100 μm circular holes with 170 μm pitch), and a 22, 60 and 122 keV point-like (1 mm diameter) radioactive sources, placed at various distances from the detector. These tests were conducted in order to investigate the general feasibility of this imaging probe and its resolving power. Measurements show the high resolution but low efficiency performance of the detector-collimator set, which is able to image the 122 keV source with <1 mm FWHM resolution

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-05-18

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

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Microstructured boron foil scintillating G-GEM detector for neutron imaging

Energy Technology Data Exchange (ETDEWEB)

Fujiwara, Takeshi, E-mail: fujiwara-t@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan); Center for Advanced Photonics, Neutron Beam Technology Team, RIKEN, Saitama (Japan); Bautista, Unico [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo (Japan); Philippine Nuclear Research Institute-Department of Science and Technology (PNRI-DOST), Commonwealth Avenue, Diliman, Quezon City (Philippines); Mitsuya, Yuki [Nuclear Professional School, The University of Tokyo, Tokai-mura, Naka-gun, Ibaraki (Japan); Takahashi, Hiroyuki [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo (Japan); Yamada, Norifumi L. [Neutron Science Laboratory, Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK) (Japan); Otake, Yoshie; Taketani, Atsushi [Center for Advanced Photonics, Neutron Beam Technology Team, RIKEN, Saitama (Japan); Uesaka, Mitsuru [Nuclear Professional School, The University of Tokyo, Tokai-mura, Naka-gun, Ibaraki (Japan); Toyokawa, Hiroyuki [Research Institute for Measurement and Analytical Instrumentation, Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan)

2016-12-01

In this study, a new simple neutron imaging gaseous detector was successfully developed by combining a micro-structured {sup 10}B foil, a glass gas electron multiplier (G-GEM), and a mirror–lens–charge-coupled device (CCD)–camera system. The neutron imaging system consists of a chamber filled with Ar/CF{sub 4} scintillating gas mixture. Inside this system, the G-GEM is mounted for gas multiplication. The neutron detection in this system is based on the reaction between {sup 10}B and neutrons. A micro-structured {sup 10}B is developed to overcome the issue of low detection efficiency. Secondary electrons excite Ar/CF{sub 4} gas molecules, and high-yield visible photons are emitted from those excited gas molecules during the gas electron multiplication process in the G-GEM holes. These photons are easily detected by a mirror–lens–CCD–camera system. A neutron radiograph is then simply formed. We obtain the neutron images of different materials with a compact accelerator-driven neutron source. We confirm that the new scintillating G-GEM-based neutron imager works properly with low gamma ray sensitivity and exhibits a good performance as a new simple digital neutron imaging device.

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

2003-06-21

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 microm thick silicon pixel detector. This room temperature system has 256 x 256 square pixels of 55 microm pitch (total sensitive area of 14 x 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 x 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.

Trends in the development of large area photon detectors for Cherenkov light imaging applications

CERN Document Server

Nappi, E

2003-01-01

Since the successful operations of hi-tech devices at OMEGA, DELPHI and SLD, the technique of Cherenkov light imaging has gone through an impressive and fruitful evolution driven by the conception of novel large area photon detectors. The well-assessed potentialities of thin CsI films, employed as reflective photoconverters in gas counters operated at atmospheric pressure, will be compared with the promising features of hybrid and multianode vacuum photomultipliers. Recently proposed single-photon gaseous detectors based on GEMs will also be reviewed.

Image simulation of high-speed imaging by high-pressure gas ionization detector

International Nuclear Information System (INIS)

Miao Jichen; Liu Ximing; Wu Zhifang

2005-01-01

The signal of the neighbor pixels is cumulated in Freight Train Inspection System because data fetch time is shorter than ion excursion time. This paper analyzes the pertinency of neighbor pixels and designs computer simulation method to generate some emulate images such as indicator image. The result indicates the high-pressure gas ionization detector can be used in high-speed digital radiography field. (authors)

X-ray imaging with photon counting hybrid semiconductor pixel detectors

CERN Document Server

Manolopoulos, S; Campbell, M; Snoeys, W; Heijne, Erik H M; Pernigotti, E; Raine, C; Smith, K; Watt, J; O'Shea, V; Ludwig, J; Schwarz, C

1999-01-01

Semiconductor pixel detectors, originally developed for particle physics experiments, have been studied as X-ray imaging devices. The performance of devices using the OMEGA 3 read-out chip bump-bonded to pixellated silicon semiconductor detectors is characterised in terms of their signal-to-noise ratio when exposed to 60 kVp X-rays. Although parts of the devices achieve values of this ratio compatible with the noise being photon statistics limited, this is not found to hold for the whole pixel matrix, resulting in the global signal-to-noise ratio being compromised. First results are presented of X-ray images taken with a gallium arsenide pixel detector bump-bonded to a new read-out chip, (MEDIPIX), which is a single photon counting read-out chip incorporating a 15-bit counter in every pixel. (author)

Application of a-Si:H radiation detectors in medical imaging

International Nuclear Information System (INIS)

Lee, Hyoung-Koo.

1995-06-01

Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 ∼ 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered γ-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at -26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the γ-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays

ST Spot Detector: a web-based application for automatic spot and tissue detection for Spatial Transcriptomics image data sets.

Science.gov (United States)

Wong, Kim; Fernández Navarro, José; Bergenstråhle, Ludvig; Ståhl, Patrik L; Lundeberg, Joakim

2018-01-17

Spatial transcriptomics (ST) is a method which combines high resolution tissue imaging with high throughput transcriptome sequencing data. This data must be aligned with the images for correct visualisation, a process that involves several manual steps. Here we present ST Spot Detector, a web tool that automates and facilitates this alignment through a user friendly interface. Open source under the MIT license, available from https://github.com/SpatialTranscriptomicsResearch/st_spot_detector. jose.fernandez.navarro@scilifelab.se. Supplementary data are available at Bioinformatics online. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

Terahertz detectors for long wavelength multi-spectral imaging.

Energy Technology Data Exchange (ETDEWEB)

Lyo, Sungkwun Kenneth; Wanke, Michael Clement; Reno, John Louis; Shaner, Eric Arthur; Grine, Albert D.

2007-10-01

The purpose of this work was to develop a wavelength tunable detector for Terahertz spectroscopy and imaging. Our approach was to utilize plasmons in the channel of a specially designed field-effect transistor called the grating-gate detector. Grating-gate detectors exhibit narrow-linewidth, broad spectral tunability through application of a gate bias, and no angular dependence in their photoresponse. As such, if suitable sensitivity can be attained, they are viable candidates for Terahertz multi-spectral focal plane arrays. When this work began, grating-gate gate detectors, while having many promising characteristics, had a noise-equivalent power (NEP) of only 10{sup -5} W/{radical}Hz. Over the duration of this project, we have obtained a true NEP of 10{sup -8} W/{radical}Hz and a scaled NEP of 10{sup -9}W/{radical}Hz. The ultimate goal for these detectors is to reach a NEP in the 10{sup -9{yields}-10}W/{radical}Hz range; we have not yet seen a roadblock to continued improvement.

Paediatric interventional cardiology: flat detector versus image intensifier using a test object

Science.gov (United States)

Vano, E.; Ubeda, C.; Martinez, L. C.; Leyton, F.; Miranda, P.

2010-12-01

Entrance surface air kerma (ESAK) values and image quality parameters were measured and compared for two biplane angiography x-ray systems dedicated to paediatric interventional cardiology, one equipped with image intensifiers (II) and the other one with dynamic flat detectors (FDs). Polymethyl methacrylate phantoms of different thicknesses, ranging from 8 to 16 cm, and a Leeds TOR 18-FG test object were used. The parameters of the image quality evaluated were noise, signal-difference-to-noise ratio (SdNR), high contrast spatial resolution (HCSR) and three figures of merit combining entrance doses and signal-to-noise ratios or HCSR. The comparisons showed a better behaviour of the II-based system in the low contrast region over the whole interval of thicknesses. The FD-based system showed a better performance in HCSR. The FD system evaluated would need around two times more dose than the II system evaluated to reach a given value of SdNR; moreover, a better spatial resolution was measured (and perceived in conventional monitors) for the system equipped with flat detectors. According to the results of this paper, the use of dynamic FD systems does not lead to an automatic reduction in ESAK or to an automatic improvement in image quality by comparison with II systems. Any improvement also depends on the setting of the x-ray systems and it should still be possible to refine these settings for some of the dynamic FDs used in paediatric cardiology.

Paediatric interventional cardiology: flat detector versus image intensifier using a test object

Energy Technology Data Exchange (ETDEWEB)

Vano, E [Radiology Department, Medicine School, Complutense University and San Carlos University Hospital, 28040 Madrid (Spain); Ubeda, C [Clinical Sciences Department, Faculty of the Science of Health and CIHDE, Tarapaca University, 18 de Septiembre 2222, Arica (Chile); Martinez, L C [Medical Physics and Radiation Protection Service, 12 de Octubre University Hospital, Madrid (Spain); Leyton, F [Institute of Public Health of Chile, Marathon 1000, Nunoa, Santiago (Chile); Miranda, P, E-mail: eliseov@med.ucm.e [Hemodynamic Department, Cardiovascular Service, Luis Calvo Mackenna Hospital, Avenida Antonio Varaas 360, Providencia, Santiago (Chile)

2010-12-07

Entrance surface air kerma (ESAK) values and image quality parameters were measured and compared for two biplane angiography x-ray systems dedicated to paediatric interventional cardiology, one equipped with image intensifiers (II) and the other one with dynamic flat detectors (FDs). Polymethyl methacrylate phantoms of different thicknesses, ranging from 8 to 16 cm, and a Leeds TOR 18-FG test object were used. The parameters of the image quality evaluated were noise, signal-difference-to-noise ratio (SdNR), high contrast spatial resolution (HCSR) and three figures of merit combining entrance doses and signal-to-noise ratios or HCSR. The comparisons showed a better behaviour of the II-based system in the low contrast region over the whole interval of thicknesses. The FD-based system showed a better performance in HCSR. The FD system evaluated would need around two times more dose than the II system evaluated to reach a given value of SdNR; moreover, a better spatial resolution was measured (and perceived in conventional monitors) for the system equipped with flat detectors. According to the results of this paper, the use of dynamic FD systems does not lead to an automatic reduction in ESAK or to an automatic improvement in image quality by comparison with II systems. Any improvement also depends on the setting of the x-ray systems and it should still be possible to refine these settings for some of the dynamic FDs used in paediatric cardiology.

A simulation study of high-resolution x-ray computed tomography imaging using irregular sampling with a photon-counting detector

International Nuclear Information System (INIS)

Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

2013-01-01

The purpose of this study was to improve the spatial resolution for the x-ray computed tomography (CT) imaging with a photon-counting detector using an irregular sampling method. The geometric shift-model of detector was proposed to produce the irregular sampling pattern and increase the number of samplings in the radial direction. The conventional micro-x-ray CT system and the novel system with the geometric shift-model of detector were simulated using analytic and Monte Carlo simulations. The projections were reconstructed using filtered back-projection (FBP), algebraic reconstruction technique (ART), and total variation (TV) minimization algorithms, and the reconstructed images were compared in terms of normalized root-mean-square error (NRMSE), full-width at half-maximum (FWHM), and coefficient-of-variation (COV). The results showed that the image quality improved in the novel system with the geometric shift-model of detector, and the NRMSE, FWHM, and COV were lower for the images reconstructed using the TV minimization technique in the novel system with the geometric shift-model of detector. The irregular sampling method produced by the geometric shift-model of detector can improve the spatial resolution and reduce artifacts and noise for reconstructed images obtained from an x-ray CT system with a photon-counting detector. -- Highlights: • We proposed a novel sampling method based on a spiral pattern to improve the spatial resolution. • The novel sampling method increased the number of samplings in the radial direction. • The spatial resolution was improved by the novel sampling method

Development of high quantum efficiency, flat panel, thick detectors for megavoltage x-ray imaging: An experimental study of a single-pixel prototype

International Nuclear Information System (INIS)

Mei, X.; Pang, G.

2005-01-01

Our overall goal is to develop a new generation of electronic portal imaging devices (EPIDs) with a quantum efficiency (QE) more than an order of magnitude higher and a spatial resolution equivalent to that of EPIDs currently used for portal imaging. A novel design of such a high QE flat-panel based EPID was introduced recently and its feasibility was investigated theoretically [see Pang and Rowlands, Med. Phys. 31, 3004 (2004)]. In this work, we constructed a prototype single-pixel detector based on the novel design. Some fundamental imaging properties including the QE, spatial resolution, and sensitivity of the prototype detector were measured with a 6 MV beam. It has been shown that the experimental results agree well with theoretical predictions and further development based on the novel design including the construction of a prototype area detector is warranted

Image timing and detector performance of a matrix ion-chamber electronic portal imaging device

International Nuclear Information System (INIS)

Greer, P.

1996-01-01

The Oncology Centre of Auckland Hospital recently purchased a Varian PortalVision TM electronic portal imaging device (EPID). Image acquisition times, input-output characteristics and contrast-detail curves of this matrix liquid ion-chamber EPID have been measured to examine the variation in imaging performance with acquisition mode. The variation in detector performance with acquisition mode has been examined. The HV cycle time can be increased to improve image quality. Consideration should be given to the acquisition mode and HV cycle time used when imaging to ensure adequate imaging performance with reasonable imaging time. (author)

A novel disk-type X-ray area imaging detector using radiophotoluminescence in silver-activated phosphate glass

International Nuclear Information System (INIS)

Kurobori, Toshio; Nakamura, Shoichi

2012-01-01

We report a novel two- and three-dimensional (2-D, 3-D) imaging detector based on the radiophotoluminescence (RPL) phenomenon in silver-activated phosphate glass (PG:Ag) and evaluate its dosimetric characteristics. A compact disk-type PG:Ag detector with a diameter of 80 mm was rotated at a rate of 400 rpm to read out the accumulated dose information and then remove the images for reuse. After X-ray exposure, three RPL dosimeter processes, i.e., preheating, reading, and erasing, were carried out with only a UV laser at 375 nm by adjusting the stepwise output levels. The 3-D images and dose distributions were rapidly reconstructed with a high spatial resolution of 1 μm and a sensitivity of 1 mGy.

The SUMO Ship Detector Algorithm for Satellite Radar Images

Directory of Open Access Journals (Sweden)

Harm Greidanus

2017-03-01

Full Text Available Search for Unidentified Maritime Objects (SUMO is an algorithm for ship detection in satellite Synthetic Aperture Radar (SAR images. It has been developed over the course of more than 15 years, using a large amount of SAR images from almost all available SAR satellites operating in L-, C- and X-band. As validated by benchmark tests, it performs very well on a wide range of SAR image modes (from Spotlight to ScanSAR and resolutions (from 1–100 m and for all types and sizes of ships, within the physical limits imposed by the radar imaging. This paper describes, in detail, the algorithmic approach in all of the steps of the ship detection: land masking, clutter estimation, detection thresholding, target clustering, ship attribute estimation and false alarm suppression. SUMO is a pixel-based CFAR (Constant False Alarm Rate detector for multi-look radar images. It assumes a K distribution for the sea clutter, corrected however for deviations of the actual sea clutter from this distribution, implementing a fast and robust method for the clutter background estimation. The clustering of detected pixels into targets (ships uses several thresholds to deal with the typically irregular distribution of the radar backscatter over a ship. In a multi-polarization image, the different channels are fused. Azimuth ambiguities, a common source of false alarms in ship detection, are removed. A reliability indicator is computed for each target. In post-processing, using the results of a series of images, additional false alarms from recurrent (fixed targets including range ambiguities are also removed. SUMO can run in semi-automatic mode, where an operator can verify each detected target. It can also run in fully automatic mode, where batches of over 10,000 images have successfully been processed in less than two hours. The number of satellite SAR systems keeps increasing, as does their application to maritime surveillance. The open data policy of the EU�

Comparison of dose and image quality of a Flat-panel detector and an image intensifier

International Nuclear Information System (INIS)

Lazzaro, M.; Friedrich, B.Q.; Luz, R.M. da; Silva, A.M.M. da

2016-01-01

With the development of new technologies, have emerged new conversion methods of X-ray image, such as flat panel detectors. The aim of this work is the comparison of entrance surface air kerma (ESAK) and image quality between an image intensifier type of detector (A) and a flat panel (B). The ESAK was obtained by placing a ionization chamber under PMMA simulators of 10, 20 and 30 cm and the image quality was obtained by using the TOR "1"8FG simulator. The ESAK to the equipment A is higher when compared to the equipment B. The high contrast resolution is better for the equipment A for all thicknesses of simulators. The equipment A has low contrast resolution with a better viewing threshold for thicknesses of 10 and 20 cm, and a worse performance for 30 cm. It is concluded that the equipment B has ESAK smaller and despite having lower resolution, in almost all cases, have appropriate image quality for diagnosis. (author)

3D reconstruction based on compressed-sensing (CS)-based framework by using a dental panoramic detector.

Science.gov (United States)

Je, U K; Cho, H M; Hong, D K; Cho, H S; Park, Y O; Park, C K; Kim, K S; Lim, H W; Kim, G A; Park, S Y; Woo, T H; Cho, S I

2016-01-01

In this work, we propose a practical method that can combine the two functionalities of dental panoramic and cone-beam CT (CBCT) features in one by using a single panoramic detector. We implemented a CS-based reconstruction algorithm for the proposed method and performed a systematic simulation to demonstrate its viability for 3D dental X-ray imaging. We successfully reconstructed volumetric images of considerably high accuracy by using a panoramic detector having an active area of 198.4 mm × 6.4 mm and evaluated the reconstruction quality as a function of the pitch (p) and the angle step (Δθ). Our simulation results indicate that the CS-based reconstruction almost completely recovered the phantom structures, as in CBCT, for p≤2.0 and θ≤6°, indicating that it seems very promising for accurate image reconstruction even for large-pitch and few-view data. We expect the proposed method to be applicable to developing a cost-effective, volumetric dental X-ray imaging system. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A new position-sensitive transmission detector for epithermal neutron imaging

International Nuclear Information System (INIS)

Schooneveld, E M; Kockelmann, W; Rhodes, N; Tardocchi, M; Gorini, G; Perelli Cippo, E; Nakamura, T; Postma, H; Schillebeeckx, P

2009-01-01

A new neutron resonant transmission (NRT) detector for epithermal neutron imaging has been designed and built for the ANCIENT CHARM project, which is developing a set of complementary neutron imaging methods for analysis of cultural heritage objects. One of the techniques being exploited is NRT with the aim of performing bulk elemental analysis. The 16-pixel prototype NRT detector consists of independent crystals of 2 x 2 mm pixel size, which allow for 2D position-sensitive transmission measurements with epithermal neutrons. First results obtained at the ISIS pulsed spallation neutron source are presented. (fast track communication)

Time-Resolved Diffuse Optical Spectroscopy and Imaging Using Solid-State Detectors: Characteristics, Present Status, and Research Challenges.

Science.gov (United States)

Alayed, Mrwan; Deen, M Jamal

2017-09-14

Diffuse optical spectroscopy (DOS) and diffuse optical imaging (DOI) are emerging non-invasive imaging modalities that have wide spread potential applications in many fields, particularly for structural and functional imaging in medicine. In this article, we review time-resolved diffuse optical imaging (TR-DOI) systems using solid-state detectors with a special focus on Single-Photon Avalanche Diodes (SPADs) and Silicon Photomultipliers (SiPMs). These TR-DOI systems can be categorized into two types based on the operation mode of the detector (free-running or time-gated). For the TR-DOI prototypes, the physical concepts, main components, figures-of-merit of detectors, and evaluation parameters are described. The performance of TR-DOI prototypes is evaluated according to the parameters used in common protocols to test DOI systems particularly basic instrumental performance (BIP). In addition, the potential features of SPADs and SiPMs to improve TR-DOI systems and expand their applications in the foreseeable future are discussed. Lastly, research challenges and future developments for TR-DOI are discussed for each component in the prototype separately and also for the entire system.

The HERMES dual-radiator ring imaging Cherenkov detector

CERN Document Server

Akopov, N; Bailey, K; Bernreuther, S; Bianchi, N; Capitani, G P; Carter, P; Cisbani, E; De Leo, R; De Sanctis, E; De Schepper, D; Dzhordzhadze, V; Filippone, B W; Frullani, S; Garibaldi, F; Hansen, J O; Hommez, B; Iodice, M; Jackson, H E; Jung, P; Kaiser, R; Kanesaka, J; Kowalczyk, R; Lagamba, L; Maas, A; Muccifora, V; Nappi, E; Negodaeva, K; Nowak, Wolf-Dieter; O'Connor, T; O'Neill, T G; Potterveld, D H; Ryckbosch, D; Sakemi, Y; Sato, F; Schwind, A; Shibata, T A; Suetsugu, K; Thomas, E; Tytgat, M; Urciuoli, G M; Van De Kerckhove, K; Van De Vyver, R; Yoneyama, S; Zhang, L F; Zohrabyan, H G

2002-01-01

The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV, which is essential to these studies. The instrument uses two radiators, C sub 4 F sub 1 sub 0 , a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes (PMT) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.

Instrumentation for Kinetic-Inductance-Detector-Based Submillimeter Radio Astronomy

Science.gov (United States)

Duan, Ran

A substantial amount of important scientific information is contained within astronomical data at the submillimeter and far-infrared (FIR) wavelengths, including information regarding dusty galaxies, galaxy clusters, and star-forming regions; however, these wavelengths are among the least-explored fields in astronomy because of the technological difficulties involved in such research. Over the past 20 years, considerable efforts have been devoted to developing submillimeter- and millimeter-wavelength astronomical instruments and telescopes. The number of detectors is an important property of such instruments and is the subject of the current study. Future telescopes will require as many as hundreds of thousands of detectors to meet the necessary requirements in terms of the field of view, scan speed, and resolution. A large pixel count is one benefit of the development of multiplexable detectors that use kinetic inductance detector (KID) technology. This dissertation presents the development of a KID-based instrument including a portion of the millimeter-wave bandpass filters and all aspects of the readout electronics, which together enabled one of the largest detector counts achieved to date in submillimeter-/millimeter-wavelength imaging arrays: a total of 2304 detectors. The work presented in this dissertation has been implemented in the MUltiwavelength Submillimeter Inductance Camera (MUSIC), a new instrument for the Caltech Submillimeter Observatory (CSO).

Medical imaging: Material change for X-ray detectors

Science.gov (United States)

Rowlands, John A.

2017-10-01

The X-ray sensitivity of radiology instruments is limited by the materials used in their detectors. A material from the perovskite family of semiconductors could allow lower doses of X-rays to be used for medical imaging. See Letter p.87

CdTe and CdZnTe gamma ray detectors for medical and industrial imaging systems

International Nuclear Information System (INIS)

Eisen, Y.; Shor, A.; Mardor, I.

1999-01-01

CdTe and CdZnTe X-ray and gamma ray detectors in the form of single elements or as segmented monolithic detectors have been shown to be useful in medical and industrial imaging systems. These detectors possess inherently better energy resolution than scintillators coupled to either photodiodes or photomultipliers, and together with application specific integrated circuits they lead to compact imaging systems of enhanced spatial resolution and better contrast resolution. Photopeak efficiencies of these detectors is greatly affected by a relatively low hole mobility-lifetime product. Utilizing these detectors as highly efficient good spectrometers, demands use of techniques to improve their charge collection properties, i.e., correct for variations in charge losses at different depths of interaction in the detector. The corrections for the large hole trapping are made either by applying electronic techniques or by fabricating detector or electrical contacts configurations which differ from the commonly used planar detectors. The following review paper is divided into three parts: The first part discusses detector contact configurations for enhancing photopeak efficiencies and the single carrier collection approach which leads to improved energy resolutions and photopeak efficiencies at high gamma ray energies. The second part demonstrates excellent spectroscopic results using thick CdZnTe segmented monolithic pad and strip detectors showing energy resolutions less than 2% FWHM at 356 keV gamma rays. The third part discusses advantages and disadvantages of CdTe and CdZnTe detectors in imaging systems and describes new developments for medical diagnostics imaging systems

A Divergence Median-based Geometric Detector with A Weighted Averaging Filter

Science.gov (United States)

Hua, Xiaoqiang; Cheng, Yongqiang; Li, Yubo; Wang, Hongqiang; Qin, Yuliang

2018-01-01

To overcome the performance degradation of the classical fast Fourier transform (FFT)-based constant false alarm rate detector with the limited sample data, a divergence median-based geometric detector on the Riemannian manifold of Heimitian positive definite matrices is proposed in this paper. In particular, an autocorrelation matrix is used to model the correlation of sample data. This method of the modeling can avoid the poor Doppler resolution as well as the energy spread of the Doppler filter banks result from the FFT. Moreover, a weighted averaging filter, conceived from the philosophy of the bilateral filtering in image denoising, is proposed and combined within the geometric detection framework. As the weighted averaging filter acts as the clutter suppression, the performance of the geometric detector is improved. Numerical experiments are given to validate the effectiveness of our proposed method.

Numerical simulation and optimal design of Segmented Planar Imaging Detector for Electro-Optical Reconnaissance

Science.gov (United States)

Chu, Qiuhui; Shen, Yijie; Yuan, Meng; Gong, Mali

2017-12-01

Segmented Planar Imaging Detector for Electro-Optical Reconnaissance (SPIDER) is a cutting-edge electro-optical imaging technology to realize miniaturization and complanation of imaging systems. In this paper, the principle of SPIDER has been numerically demonstrated based on the partially coherent light theory, and a novel concept of adjustable baseline pairing SPIDER system has further been proposed. Based on the results of simulation, it is verified that the imaging quality could be effectively improved by adjusting the Nyquist sampling density, optimizing the baseline pairing method and increasing the spectral channel of demultiplexer. Therefore, an adjustable baseline pairing algorithm is established for further enhancing the image quality, and the optimal design procedure in SPIDER for arbitrary targets is also summarized. The SPIDER system with adjustable baseline pairing method can broaden its application and reduce cost under the same imaging quality.

Flat detectors and their clinical applications

International Nuclear Information System (INIS)

Spahn, Martin

2005-01-01

Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray conversion process, using cesium iodide scintillators. It offers considerable advantages in radiography, angiography and fluoroscopy. The other method employs a direct converter such as selenium which is particularly suitable for mammography. Both flat detector technologies are based on amorphous silicon active pixel matrices. Flat detectors facilitate the clinical workflow in radiographic rooms, foster improved image quality and provide the potential to reduce dose. This added value is based on their large dynamic range, their high sensitivity to X-rays and the instant availability of the image. Advanced image processing is instrumental in these improvements and expand the range of conventional diagnostic methods. In angiography and fluoroscopy the transition from image intensifiers to flat detectors is facilitated by ample advantages they offer, such as distortion-free images, excellent coarse contrast, large dynamic range and high X-ray sensitivity. These characteristics and their compatibility with strong magnetic fields are the basis for improved diagnostic methods and innovative interventional applications. (orig.)

Dose energy dependence in proton imaging with thin detector

Energy Technology Data Exchange (ETDEWEB)

Denyak, V.V., E-mail: denyak@gmail.com [National Science Centre Kharkov Institute of Physics and Technology, St. Akademicheskaya 1, Kharkov 61108 (Ukraine); Federal University of Technology - Parana, Av. Sete de Setembro 3165, Curitiba 80230-901 (Brazil); Schelin, H.R. [Pele Pequeno Principe Research Institute, Av. Silva Jardim 1632, Curitiba 80250-200 (Brazil); Federal University of Technology - Parana, Av. Sete de Setembro 3165, Curitiba 80230-901 (Brazil); Silva, R.C.L.; Kozuki, C.; Paschuk, S.A.; Milhoretto, E. [Federal University of Technology - Parana, Av. Sete de Setembro 3165, Curitiba 80230-901 (Brazil)

2012-07-15

Since the earliest works proposing the use of protons for imaging, the main advantage of protons over X-rays was expected to be a result of the specific property of the proton flux dropping off very steeply at the end of the particle range. This idea was declared but was not checked. In the present work, this assumption was investigated using the Monte Carlo simulation for the case of registration of protons with a thin detector. - Highlights: Black-Right-Pointing-Pointer Principal idea of proton imaging 'to work at the end of the range' was tested. Black-Right-Pointing-Pointer The case of thin detector was investigated. Black-Right-Pointing-Pointer The dose energy dependence was calculated using computer simulation.

Aging of imaging properties of a CMOS flat-panel detector for dental cone-beam computed tomography

Science.gov (United States)

Kim, D. W.; Han, J. C.; Yun, S.; Kim, H. K.

2017-01-01

We have experimentally investigated the long-term stability of imaging properties of a flat-panel detector in conditions used for dental x-ray imaging. The detector consists of a CsI:Tl layer and CMOS photodiode pixel arrays. Aging simulations were carried out using an 80-kVp x-ray beam at an air-kerma rate of approximately 5 mGy s-1 at the entrance surface of the detector with a total air kerma of up to 0.6 kGy. Dark and flood-field images were periodically obtained during irradiation, and the mean signal and noise levels were evaluated for each image. We also evaluated the modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). The aging simulation showed a decrease in both the signal and noise of the gain-offset-corrected images, but there was negligible change in the signal-to-noise performance as a function of the accumulated dose. The gain-offset correction for analyzing images resulted in negligible changes in MTF, NPS, and DQE results over the total dose. Continuous x-ray exposure to a detector can cause degradation in the physical performance factors such the detector sensitivity, but linear analysis of the gain-offset-corrected images can assure integrity of the imaging properties of a detector during its lifetime.

Image plane detector spectrophotometer - Application to O2 atmospheric band nightglow

Science.gov (United States)

Luo, Mingzhao; Yee, Jeng-Hwa; Hays, Paul B.

1988-01-01

A new variety of low resolution spectrometer is described. This device, an image plane detector spectrophotometer, has high sensitivity and modest resolution sufficient to determine the rotational temperature and brightness of molecular band emissions. It uses an interference filter as a dispersive element and a multichannel image plane detector as the photon collecting device. The data analysis technqiue used to recover the temperature of the emitter and the emission brightness is presented. The atmospheric band of molecular oxygen is used to illustrate the use of the device.

Neutron diffractometer for bio-crystallography (BIX) with an imaging plate neutron detector

Energy Technology Data Exchange (ETDEWEB)

Niimura, Nobuo [Japan Atomic Energy Research Inst., Ibaraki-ken (Japan)

1994-12-31

We have constructed a dedicated diffractometer for neutron crystallography in biology (BIX) on the JRR-3M reactor at JAERI (Japan Atomic Energy Research Institute). The diffraction intensity from a protein crystal is weaker than that from most inorganic materials. In order to overcome the intensity problem, an elastically bent silicon monochromator and a large area detector system were specially designed. A preliminary result of diffraction experiment using BIX has been reported. An imaging plate neutron detector has been developed and a feasibility experiment was carried out on BIX. Results are reported. An imaging plate neutron detector has been developed and a feasibility test was carried out using BIX.

Optimizing detector thickness in dual-shot dual-energy x-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Woon; Kam, Soohwa; Youn, Hanbean; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of)

2015-05-15

As a result, there exist apparent limitations in the conventional two-dimensional (2D) radiography: One is that the contrast between the structure of interest and the background in a radiograph is much less than the intrinsic subject contrast (i.e. the difference between their attenuation coefficients; Another is that the superimposed anatomical structures in the 2D radiograph results in an anatomical background clutter that may decrease the conspicuity of subtle underlying features. These limitations in spatial and material discrimination are important motivations for the recent development of 3D (e.g. tomosynthesis) and dual energy imaging (DEI) systems. DEI technique uses a combination of two images obtained at two different energies in successive x-ray exposures by rapidly switching the kilovolage (kV) applied to the x-ray tube. Commercial DEI systems usually employ a 'single' of flat-panel detector (FPD) to obtain two different kV images. However, we have a doubt in the use of the same detector for acquiring two different projections for the low- and high-kV setups because it is typically known that there exists an optimal detector thickness regarding specific imaging tasks or energies used.

A piecewise-focused high DQE detector for MV imaging.

Science.gov (United States)

Star-Lack, Josh; Shedlock, Daniel; Swahn, Dennis; Humber, Dave; Wang, Adam; Hirsh, Hayley; Zentai, George; Sawkey, Daren; Kruger, Isaac; Sun, Mingshan; Abel, Eric; Virshup, Gary; Shin, Mihye; Fahrig, Rebecca

2015-09-01

lightweight edge phantom to generate MTF measurements at MV energies and shows its functional equivalence to the more cumbersome slit-based method. Measured and simulated DQE(0)'s of the pixelated CWO detector were 22% and 26%, respectively. The average measured and simulated ratios of CWO DQE(f) to Cu-GOS DQE(f) across the frequency range of 0.0-0.62 mm(-1) were 23 and 29, respectively. 2D and 3D imaging studies confirmed the large dose efficiency improvement and that focus was maintained across the field of view. In the CWO CBCT images, the measured spatial resolution was 7 lp/cm. The contrast-to-noise ratio was dramatically improved reflecting a 22 × sensitivity increase relative to Cu-GOS. The CWO scintillator material showed significantly higher stability and light yield than the BGO material. An efficient piecewise-focused pixelated strip scintillator for MV imaging is described that offers more than a 20-fold dose efficiency improvement over Cu-GOS.

Electrical characteristics of hybrid detector based Gd2O2S:Tb-Selenium for digital radiation imaging

International Nuclear Information System (INIS)

Kang, Sang-Sik; Park, Ji-Koon; Choi, Jang-Yong; Cha, Byung-Yul; Cho, Sung-Ho; Nam, Sang-Hee

2005-01-01

Fine Gd 2 O 2 S:Tb powders were synthesized by using a solution-combustion method for a high-resolution digital X-ray imaging detector. The PL spectrum showed that the phosphor was fully crystallized and that the Tb 3+ ions substituted well for the Gd 3+ sites. To investigate the X-ray response of the phosphor, a uniform Gd 2 O 2 S:Tb film was grown using a screen-printing method. The X-ray sensitivities of the 100 μm-Gd 2 O 2 S:Tb/30 μm -Se and 200 μm -Se detector were 470 and 420 pC/cm 2 /mR, respectively, at an electric field of 10 V/μm. The results of the study suggest that the hybrid detector has a significant potential in the application of digital radiography and fluoroscopy systems

A study on characteristics of X-ray detector for CCD-based EPID

International Nuclear Information System (INIS)

Chung, Yong Hyun

1999-02-01

The combination of the metal plate/phosphor screen as a x-ray detector with a CCD camera is the most popular detector system among various electronic portal imaging devices (EPIDs). There is a need to optimize the thickness of the metal plate/phosphor screen with high detection efficiency and high spatial resolution for effective transferring of anatomical information. In this study, the thickness dependency on the detection efficiency and the spatial resolution of the metal plate/phosphor screen was investigated by calculation and measurement. The result can be used to determine the optimal thickness of the metal plate as well as of the phosphor screen for the x-ray detector design of therapeutic x-ray imaging and for any specific application. Bremsstrahlung spectrum was calculated by Monte Carlo simulation and by Schiff formula. The detection efficiency was calculated from the total absorbed energy in the phosphor screen using the Monte Carlo simulation and the light output was measured. The spatial resolution, which was defined from the spatial distribution of the absorbed energy, was also calculated and the edge spread function was measured. It was found that the detection efficiency and the spatial resolution were mainly determined by the thickness of metal plate and phosphor screen, respectively. It was also revealed that the detection efficiency and the spatial resolution have trade-off in term of the thickness of the phosphor screen. As the phosphor thickness increases, the detection efficiency increases but the spatial resolution decreases. The curve illustrating the trade-off between the detection efficiency and the spatial resolution of the metal plate/phosphor screen detector is obtained as a function of the phosphor thickness. Based on the calculations, prototype CCD-based EPID was developed and then tested by acquiring phantom images for 6 MV x-ray beam. While, among the captured images, each frame suffered from quantum noise, the frame averaging

High-Resolution Detector For X-Ray Diffraction

Science.gov (United States)

Carter, Daniel C.; Withrow, William K.; Pusey, Marc L.; Yost, Vaughn H.

1988-01-01

Proposed x-ray-sensitive imaging detector offers superior spatial resolution, counting-rate capacity, and dynamic range. Instrument based on laser-stimulated luminescence and reusable x-ray-sensitive film. Detector scans x-ray film line by line. Extracts latent image in film and simultaneously erases film for reuse. Used primarily for protein crystallography. Principle adapted to imaging detectors for electron microscopy and fluorescence spectroscopy and general use in astronomy, engineering, and medicine.

The Belle II imaging Time-of-Propagation (iTOP) detector

Science.gov (United States)

Fast, J.; Belle II Barrel Particle Identification Group

2017-12-01

High precision flavor physics measurements are an essential complement to the direct searches for new physics at the LHC ATLAS and CMS experiments. Such measurements will be performed using the upgraded Belle II detector that will take data at the SuperKEKB accelerator. With 40x the luminosity of KEKB, the detector systems must operate efficiently at much higher rates than the original Belle detector. A central element of the upgrade is the barrel particle identification system. Belle II has built and installed an imaging-Time-of-Propagation (iTOP) detector. The iTOP uses quartz optics as Cherenkov radiators. The photons are transported down the quartz bars via total internal reflection with a spherical mirror at the forward end to reflect photons to the backward end where they are imaged onto an array of segmented Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMTs). The system is read out using giga-samples per second waveform sampling Application-Specific Integrated Circuits (ASICs). The combined timing and spatial distribution of the photons for each event are used to determine particle species. This paper provides an overview of the iTOP system.

HIGH SPATIAL RESOLUTION IMAGING OF INERTIAL FUSION TARGET PLASMAS USING BUBBLE NEUTRON DETECTORS

International Nuclear Information System (INIS)

FISHER, R.K.

2003-01-01

OAK B202 HIGH SPATIAL RESOLUTION IMAGING OF INERTIAL FUSION TARGET PLASMAS USING BUBBLE NEUTRON DETECTORS. Bubble detectors, which can detect neutrons with a spatial 5 to 30 (micro), are the most promising approach to imaging NIF target plasmas with the desired 5 (micro) spatial resolution in the target plane. Gel bubble detectors are being tested to record neutron images of ICF implosions in OMEGA experiments. By improving the noise reduction techniques used in analyzing the data taken in June 2000, we have been able to image the neutron emission from 6 · 10 13 yield DT target plasmas with a target plane spatial resolution of ∼ 140 (micro). As expected, the spatial resolution was limited by counting statistics as a result of the low neutron detection efficiency of the easy-to-use gel bubble detectors. The results have been submitted for publication and will be the subject of an invited talk at the October 2001 Meeting of the Division of Plasma Physics of the American Physical Society. To improve the counting statistics, data was taken in May 2001 using a stack of four gel detectors and integrated over a series of up to seven high-yield DT shots. Analysis of the 2001 data is still in its early stages. Gel detectors were chosen for these initial tests since the bubbles can be photographed several hours after the neutron exposure. They consist of ∼ 5000 drops (∼ 100 (micro) in diameter) of bubble detector liquid/cm 3 suspended in an inactive support gel that occupies ∼ 99% of the detector volume. Using a liquid bubble chamber detector and a light scattering system to record the bubble locations a few microseconds after the neutron exposure when the bubbles are ∼ 10 (micro) in diameter, should result in ∼ 1000 times higher neutron detection efficiency and a target plane resolution on OMEGA of ∼ 10 to 50 (micro)

The spatial resolution of silicon-based electron detectors in beta-autoradiography.

Science.gov (United States)

Cabello, Jorge; Wells, Kevin

2010-03-21

Thin tissue autoradiography is an imaging modality where ex-vivo tissue sections are placed in direct contact with autoradiographic film. These tissue sections contain a radiolabelled ligand bound to a specific biomolecule under study. This radioligand emits beta - or beta+ particles ionizing silver halide crystals in the film. High spatial resolution autoradiograms are obtained using low energy radioisotopes, such as (3)H where an intrinsic 0.1-1 microm spatial resolution can be achieved. Several digital alternatives have been presented over the past few years to replace conventional film but their spatial resolution has yet to equal film, although silicon-based imaging technologies have demonstrated higher sensitivity compared to conventional film. It will be shown in this work how pixel size is a critical parameter for achieving high spatial resolution for low energy uncollimated beta imaging. In this work we also examine the confounding factors impeding silicon-based technologies with respect to spatial resolution. The study considers charge diffusion in silicon and detector noise, and this is applied to a range of radioisotopes typically used in autoradiography. Finally an optimal detector geometry to obtain the best possible spatial resolution for a specific technology and a specific radioisotope is suggested.

Uniform competency-based local feature extraction for remote sensing images

Science.gov (United States)

Sedaghat, Amin; Mohammadi, Nazila

2018-01-01

Local feature detectors are widely used in many photogrammetry and remote sensing applications. The quantity and distribution of the local features play a critical role in the quality of the image matching process, particularly for multi-sensor high resolution remote sensing image registration. However, conventional local feature detectors cannot extract desirable matched features either in terms of the number of correct matches or the spatial and scale distribution in multi-sensor remote sensing images. To address this problem, this paper proposes a novel method for uniform and robust local feature extraction for remote sensing images, which is based on a novel competency criterion and scale and location distribution constraints. The proposed method, called uniform competency (UC) local feature extraction, can be easily applied to any local feature detector for various kinds of applications. The proposed competency criterion is based on a weighted ranking process using three quality measures, including robustness, spatial saliency and scale parameters, which is performed in a multi-layer gridding schema. For evaluation, five state-of-the-art local feature detector approaches, namely, scale-invariant feature transform (SIFT), speeded up robust features (SURF), scale-invariant feature operator (SFOP), maximally stable extremal region (MSER) and hessian-affine, are used. The proposed UC-based feature extraction algorithms were successfully applied to match various synthetic and real satellite image pairs, and the results demonstrate its capability to increase matching performance and to improve the spatial distribution. The code to carry out the UC feature extraction is available from href="https://www.researchgate.net/publication/317956777_UC-Feature_Extraction.

Time-of-flight mass spectrometer using an imaging detector and a rotating electric field

International Nuclear Information System (INIS)

Katayama, Atsushi; Kameo, Yutaka; Nakashima, Mikio

2008-01-01

A new technique for minor isotope analysis that uses a rotating electric field and an imaging detector is described. The rotating electric field is generated by six cylindrically arranged plane electrodes with multi-phase sinusoidal wave voltage. When ion packets that are discriminated by time-of-flight enter the rotating electric field, they are circularly deflected, rendering a spiral image on the fluorescent screen of the detector. This spiral image represents m/z values of ions as the position and abundance of ions as brightness. For minor isotopes analyses, the micro channel plate detector under gate control operation is used to eliminate the influence of high intensity of major isotopes. (author)

Adaptive differential correspondence imaging based on sorting technique

Directory of Open Access Journals (Sweden)

Heng Wu

2017-04-01

Full Text Available We develop an adaptive differential correspondence imaging (CI method using a sorting technique. Different from the conventional CI schemes, the bucket detector signals (BDS are first processed by a differential technique, and then sorted in a descending (or ascending order. Subsequently, according to the front and last several frames of the sorted BDS, the positive and negative subsets (PNS are created by selecting the relative frames from the reference detector signals. Finally, the object image is recovered from the PNS. Besides, an adaptive method based on two-step iteration is designed to select the optimum number of frames. To verify the proposed method, a single-detector computational ghost imaging (GI setup is constructed. We experimentally and numerically compare the performance of the proposed method with different GI algorithms. The results show that our method can improve the reconstruction quality and reduce the computation cost by using fewer measurement data.

Electron imaging with Medipix2 hybrid pixel detector

CERN Document Server

McMullan, G; Chen, S; Henderson, R; Llopart, X; Summerfield, C; Tlustos, L; Faruqi, A R

2007-01-01

The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 μm×55 μm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 μm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach 35% of that expected for a perfect detector (4/π2). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/π). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected v...

The Use of Radiation Detectors in Medicine: The Future of Molecular Imaging and Multimodality Imaging: Advantages and Technological Challenges (3/3)

CERN Multimedia

CERN. Geneva

2009-01-01

The development of radiation detectors in the field of nuclear and particle physics has had a terrific impact in medical imaging since this latter discipline took off in late ’70 with the invention of the CT scanners. The massive use in High Energy Physics of position sensitive gas detectors, of high Z and high density scintillators coupled to Photomultiplier (PMT) and Position Sensitive Photomultipliers (PSPMT), and of solid state detectors has triggered during the last 30 years a series of novel applications in Medical Imaging with ionizing radiation. The accelerated scientific progression in genetics and molecular biology has finally generated what it is now called Molecular Imaging. This field of research presents additional challenges not only in the technology of radiation detector, but more and more in the ASIC electronics, fast digital readout and parallel software. In this series of three lectures I will try to present how high energy physics and medical imaging development have both benefited by t...

High resolution imaging detectors and applications

CERN Document Server

Saha, Swapan K

2015-01-01

Interferometric observations need snapshots of very high time resolution of the order of (i) frame integration of about 100 Hz or (ii) photon-recording rates of several megahertz (MHz). Detectors play a key role in astronomical observations, and since the explanation of the photoelectric effect by Albert Einstein, the technology has evolved rather fast. The present-day technology has made it possible to develop large-format complementary metal oxide–semiconductor (CMOS) and charge-coupled device (CCD) array mosaics, orthogonal transfer CCDs, electron-multiplication CCDs, electron-avalanche photodiode arrays, and quantum-well infrared (IR) photon detectors. The requirements to develop artifact-free photon shot noise-limited images are higher sensitivity and quantum efficiency, reduced noise that includes dark current, read-out and amplifier noise, smaller point-spread functions, and higher spectral bandwidth. This book aims to address such systems, technologies and design, evaluation and calibration, control...

Speckle imaging with the PAPA detector. [Precision Analog Photon Address

Science.gov (United States)

Papaliolios, C.; Nisenson, P.; Ebstein, S.

1985-01-01

A new 2-D photon-counting camera, the PAPA (precision analog photon address) detector has been built, tested, and used successfully for the acquisition of speckle imaging data. The camera has 512 x 512 pixels and operates at count rates of at least 200,000/sec. In this paper, technical details on the camera are presented and some of the laboratory and astronomical results are included which demonstrate the detector's capabilities.

Multiple event 2D image intensifier scintillation detector

International Nuclear Information System (INIS)

Thieberger, P.; Wegner, H.E.; Lee, R.C.

1981-01-01

An image intensifier scintillation detector has been developed for the simultaneous detection of multiple light or heavy ions down to very low energies. The relative X-Y positions of each ion are read out by digitization of a television image of the light amplified scintillations. The maximum data rate is limited by the present television scan speed to 15 multiple events per second and to about one event second by the microcomputer presently used to store and process the data. (orig.)

TSV last for hybrid pixel detectors: Application to particle physics and imaging experiments

CERN Document Server

Henry, D; Berthelot, A; Cuchet, R; Chantre, C; Campbell, M

Hybrid pixel detectors are now widely used in particle physics experiments and at synchrotron light sources. They have also stimulated growing interest in other fields and, in particular, in medical imaging. Through the continuous pursuit of miniaturization in CMOS it has been possible to increase the functionality per pixel while maintaining or even shrinking pixel dimensions. The main constraint on the more extensive use of the technology in all fields is the cost of module building and the difficulty of covering large areas seamlessly [1]. On another hand, in the field of electronic component integration, a new approach has been developed in the last years, called 3D Integration. This concept, based on using the vertical axis for component integration, allows improving the global performance of complex systems. Thanks to this technology, the cost and the form factor of components could be decreased and the performance of the global system could be enhanced. In the field of radiation imaging detectors the a...

Modelling of the small pixel effect in gallium arsenide X-ray imaging detectors

CERN Document Server

Sellin, P J

1999-01-01

A Monte Carlo simulation has been carried out to investigate the small pixel effect in highly pixellated X-ray imaging detectors fabricated from semi-insulating gallium arsenide. The presence of highly non-uniform weighting fields in detectors with a small pixel geometry causes the majority of the induced signal to be generated when the moving charges are close to the pixellated contacts. The response of GaAs X-ray imaging detectors is further complicated by the presence of charge trapping, particularly of electrons. In this work detectors are modelled with a pixel pitch of 40 and 150 mu m, and with thicknesses of 300 and 500 mu m. Pulses induced in devices with 40 mu m pixels are due almost totally to the movement of the lightly-trapped holes and can exhibit significantly higher charge collection efficiencies than detectors with large electrodes, in which electron trapping is significant. Details of the charge collection efficiencies as a function of interaction depth in the detector and of the incident phot...

Quantitative image quality evaluation of pixel-binning in a flat-panel detector for x-ray fluoroscopy

International Nuclear Information System (INIS)

Srinivas, Yogesh; Wilson, David L.

2004-01-01

X-ray fluoroscopy places stringent design requirements on new flat-panel (FP) detectors, requiring both low-noise electronics and high data transfer rates. Pixel-binning, wherein data from more that one detector pixel are collected simultaneously, not only lowers the data transfer rate but also increases x-ray counts and pixel signal-to-noise ratio (SNR). In this study, we quantitatively assessed image quality of image sequences from four acquisition methods; no-binning and three types of binning; in synthetic images using a clinically relevant task of detecting an extended guidewire in a four-alternative forced-choice paradigm. Binning methods were conventional data-line (D) and gate-line (G) binning, and a novel method in which alternate frames in an image sequence used D and G binning. Two detector orientations placed the data lines either parallel or perpendicular to the guide wire. At a low exposure of 0.6 μR (1.548x10 -10 C/kg) per frame, irrespective of detector orientation, D binning with its reduced electronic noise was significantly (p -10 C/kg) per frame, with data lines parallel to the guidewire, detection with D binning was significantly (p<0.1) better than G binning. However, with data lines perpendicular to the guidewire, G binning was significantly (p<0.1) better than D binning because the partial area effect was reduced. Alternate binning was the best binning method when results were averaged over both orientations, and it was as good as the best binning method at either orientation. In addition, at low and high exposures, alternate binning gave a temporally fused image with a smooth guidewire, an important image quality feature not assessed in a detection experiment. While at high exposure, detection with no binning was as good, or better, than the best binning method, it might be impractical at fluoroscopy imaging rates. A computational observer model based on signal detection theory successfully fit data and was used to predict effects of

DUNBID, the Delft University neutron backscattering imaging detector

International Nuclear Information System (INIS)

Bom, V.R.; Eijk, C.W.E. van; Ali, M.A.

2005-01-01

In the search for low-metallic land mines, the neutron backscattering technique may be applied if the soil is sufficiently dry. An advantage of this method is the speed of detection: the scanning speed may be made comparable to that of a metal detector. A two-dimensional position sensitive detector is tested to obtain an image of the back scattered thermal neutron radiation. Results of experiments using a radionuclide neutron source are presented. The on-mine to no-mine signal ratio can be improved by the application of a window on the neutron time-of-flight. Results using a pulsed neutron generator are also presented

Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

Energy Technology Data Exchange (ETDEWEB)

Zvolsky, Milan

2017-12-15

In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

International Nuclear Information System (INIS)

Zvolsky, Milan

2017-12-01

In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

Development of a Gamma-Ray Detector for Z-Selective Radiographic Imaging

International Nuclear Information System (INIS)

Brandis, Michal

2013-11-01

Dual-Discrete Energy Gamma-Radiography (DDEGR) is a method for Special Nuclear Materials (SNM) detection. DDEGR utilizes 15.11 and 4.43 MeV gamma-rays produced in the 11B(d,n)12C reaction, in contrast to the conventional use of continuous Bremsstrahlung radiation. The clean and well separated gamma-rays result in high contrast sensitivity, enabling detection of small quantities of SNM. The most important aspects of a DDEGR system were discussed, simulated, measured and demonstrated. An experimental measurement of gamma-ray yields from the 11B(d,n)12C reaction showed that the yields from deuterons with 3{12 MeV energy are 2{201010 N/sr/mC 4.4 MeV gamma- rays and 2{5109 N/sr/mC 15.1 MeV gamma-rays. The measured neutron yields show that the neutron energies extend to 15-23 MeV for the same deuteron energy range. A simplied inspection system was simulated with GEANT4, showing that the ect of scattering on the signal measured in the detector is acceptable. Considering the reaction gamma yields, 1.8 mA deuteron current is required for separation of high-Z materials from medium- and low-Z materials and a 4.5 mA current is required for the additional capability of separating benign high-Z materials from SNM. The main part of the work was development of a detector suitable for a DDEGR system | Time Resolved Event Counting Optical Radiation (TRECOR) detector. TRECOR detector is a novel spectroscopic imaging detector for gamma-rays within the MeV energy range that uses an event counting image intensier with gamma-rays for the rst time. Neutrons that accompany the gamma radiation enable to implement, in parallel, Fast Neutron Resonance Radiography (FNRR), a method for explosives detection. A second generation detector, TRECOR-II, is capable of detecting gamma-rays and neutrons in parallel, separating them to create particle-specic images and energy-specic images for each particle, thus enabling simultaneous implementation of the two detection methods. A full DDEGR laboratory

Positron emission tomography with additional γ-ray detectors for multiple-tracer imaging.

Science.gov (United States)

Fukuchi, Tomonori; Okauchi, Takashi; Shigeta, Mika; Yamamoto, Seiichi; Watanabe, Yasuyoshi; Enomoto, Shuichi

2017-06-01

Positron emission tomography (PET) is a useful imaging modality that quantifies the physiological distributions of radiolabeled tracers in vivo in humans and animals. However, this technique is unsuitable for multiple-tracer imaging because the annihilation photons used for PET imaging have a fixed energy regardless of the selection of the radionuclide tracer. This study developed a multi-isotope PET (MI-PET) system and evaluated its imaging performance. Our MI-PET system is composed of a PET system and additional γ-ray detectors. The PET system consists of pixelized gadolinium orthosilicate (GSO) scintillation detectors and has a ring geometry that is 95 mm in diameter with an axial field of view of 37.5 mm. The additional detectors are eight bismuth germanium oxide (BGO) scintillation detectors, each of which is 50 × 50 × 30 mm 3 , arranged into two rings mounted on each side of the PET ring with a 92-mm-inner diameter. This system can distinguish between different tracers using the additional γ-ray detectors to observe prompt γ-rays, which are emitted after positron emission and have an energy intrinsic to each radionuclide. Our system can simultaneously acquire double- (two annihilation photons) and triple- (two annihilation photons and a prompt γ-ray) coincidence events. The system's efficiency for detecting prompt de-excitation γ-rays was measured using a positron-γ emitter, 22 Na. Dual-radionuclide ( 18 F and 22 Na) imaging of a rod phantom and a mouse was performed to demonstrate the performance of the developed system. Our system's basic performance was evaluated by reconstructing two images, one containing both tracers and the other containing just the second tracer, from list-mode data sets that were categorized by the presence or absence of the prompt γ-ray. The maximum detection efficiency for 1275 keV γ-rays emitted from 22 Na was approximately 7% at the scanner's center, and the minimum detection efficiency was 5.1% at the edge of

High-resolution brain SPECT imaging by combination of parallel and tilted detector heads.

Science.gov (United States)

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Morimoto, Yuichi; Kobashi, Keiji; Ueno, Yuichiro

2015-10-01

To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations. In the simulation study, the tilt angle of the detector heads relative to the axis was 45°. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The ordered-subsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison. The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The cold-rod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT. PT-SPECT provides improved image resolution at not only upper but also at

An investigation of the performance of a coaxial HPGe detector operating in a magnetic resonance imaging field

Energy Technology Data Exchange (ETDEWEB)

Harkness, L.J., E-mail: ljh@ns.ph.liv.ac.u [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Boston, A.J.; Boston, H.C.; Cole, P.; Cresswell, J.R.; Filmer, F.; Jones, M.; Judson, D.S.; Nolan, P.J.; Oxley, D.C.; Sampson, J.A.; Scraggs, D.P.; Slee, M.J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Bimson, W.E.; Kemp, G.J. [MARIARC, University of Liverpool, Liverpool L69 3GE (United Kingdom); Groves, J.; Headspith, J.; Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Cooper, R.J. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States)

2011-05-11

Nuclear medical imaging modalities such as positron emission tomography and single photon emission computed tomography are used to probe physiological functions of the body by detecting gamma rays emitted from biologically targeted radiopharmaceuticals. A system which is capable of simultaneous data acquisition for nuclear medical imaging and magnetic resonance imaging is highly sought after by the medical imaging community. Such a device could provide a more complete medical insight into the functions of the body within a well-defined structural context. However, acquiring simultaneous nuclear/MRI sequences are technically challenging due to the conventional photomultiplier tube readout employed by most existing scintillator detector systems. A promising solution is a nuclear imaging device composed of semiconductor detectors that can be operated with a standard MRI scanner. However, the influence of placing a semiconductor detector such as high purity germanium (HPGe) within or close to the bore of an MRI scanner, where high magnetic fields are present, is not well understood. In this paper, the performance of a HPGe detector operating in a high strength static (B{sub S}) MRI field along with fast switching gradient fields and radiofrequency from the MRI system has been assessed. The influence of the B{sub S} field on the energy resolution of the detector has been investigated for various positions and orientations of the detector within the magnetic field. The results have then been interpreted in terms of the influence of the B{sub S} field on the charge collection properties. MRI images have been acquired with the detector situated at the entrance of the MRI bore to investigate the effects of simultaneous data acquisition on detector performance and MRI imaging.

Development of a circular shape Si-PM-based detector ring for breast-dedicated PET system

Science.gov (United States)

Nakanishi, Kouhei; Yamamoto, Seiichi; Watabe, Hiroshi; Abe, Shinji; Fujita, Naotoshi; Kato, Katsuhiko

2018-02-01

In clinical situations, various breast-dedicated positron emission tomography (PET) systems have been used. However, clinical breast-dedicated PET systems have polygonal detector ring. Polygonal detector ring sometimes causes image artifact, so complicated reconstruction algorithm is needed to reduce artifact. Consequently, we developed a circular detector ring for breast-dedicated PET to obtain images without artifact using a simple reconstruction algorithm. We used Lu1.9Gd0.1SiO5 (LGSO) scintillator block which was made of 1.5 x 1.9 x 15 mm pixels that were arranged in an 8 x 24 matrix. As photodetectors, we used silicon photomultiplier (Si-PM) arrays whose channel size was 3 x 3 mm. A detector unit was composed of four scintillator blocks, 16 Si-PM arrays and a light guide. The developed detector unit had angled configuration since the light guide was bending. A detector unit had three gaps with an angle of 5.625° between scintillator blocks. With these configurations, we could arrange 64 scintillator blocks in nearly circular shape (regular 64-sided polygon) using 16 detector units. The use of the smaller number of detector units could reduce the size of the front-end electronics circuits. The inner diameter of the developed detector ring was 260 mm. This size was similar to those of brain PET systems, so our breast-dedicated PET detector ring can measure not only breast but also brain. Measured radial, tangential and axial spatial resolution of the detector ring reconstructed by the filtered back-projection (FBP) algorithm were 2.1 mm FWHM, 2.0 mm FWHM and 1.7 mm FWHM at center of field of view (FOV), respectively. The sensitivity was 2.0% at center of the axial FOV. With the developed detector ring, we could obtain high resolution image of the breast phantom and the brain phantom. We conclude that our developed Si-PM-based detector ring is promising for a high resolution breast-dedicated PET system that can also be used for brain PET system.

Research of optical coherence tomography microscope based on CCD detector

Science.gov (United States)

Zhang, Hua; Xu, Zhongbao; Zhang, Shuomo

2008-12-01

The reference wave phase was modulated with a sinusoidal vibrating mirror attached to a Piezoelectric Transducer (PZT), the integration was performed by a CCD, and the charge storage period of the CCD image sensor was one-quarter period of the sinusoidal phase modulation. With the frequency- synchronous detection technique, four images (four frames of interference pattern) were recorded during one period of the phase modulation. In order to obtain the optimum modulation parameter, the values of amplitude and phase of the sinusoidal phase modulation were determined by considering the measurement error caused by the additive noise contained in the detected values. The PZT oscillation was controlled by a closed loop control system based on PID controller. An ideal discrete digital sine function at 50Hz with adjustable amplitude was used to adjust the vibrating of PZT, and a digital phase shift techniques was used to adjust vibrating phase of PZT so that the phase of the modulation could reach their optimum values. The CCD detector was triggered with software at 200Hz. Based on work above a small coherent signal masked by the preponderant incoherent background with a CCD detector was obtained.

Psychophysical evaluation of the image quality of a dynamic flat-panel digital x-ray image detector using the threshold contrast detail detectability (TCDD) technique

Science.gov (United States)

Davies, Andrew G.; Cowen, Arnold R.; Bruijns, Tom J. C.

1999-05-01

manner to the DSF systems for the TCDD comparisons. This would suggest that FDXD would therefore perform adequately in a clinical fluoroscopic environment and our initial clinical experiences support this. Noise reduction processing of the fluoroscopic data acquired on FDXD was also found to further improve TCDD performance for FDXD. FDXD therefore combines acceptable fluoroscopic performance with excellent radiographic (snap shot) imaging fidelity, allowing the possibility of a universal x-ray detector to be developed, based on FDXD's technology. It is also envisaged that fluoroscopic performance will be improved by the development of digital image enhancement techniques specifically tailored to the characteristics of the FDXD detector.

Control of the neutron detector count rate by optical imaging

International Nuclear Information System (INIS)

Roquemore, A.L.; Johnson, L.C.

1992-01-01

The signal processing electronics used for the NE451 detectors on the TFTR multichannel neutron collimator are presently showing saturation effects at high counting rates equivalent to neutron yields of ∼10 16 n/s. While nonlinearity due to pulse pileup can be corrected for in most present TFTR experiments, additional steps are required for neutron source strengths above ∼3x10 16 n/s. These pulse pileup effects could be reduced by inserting sleeves in the collimator shielding to reduce the neutron flux in the vicinity of the detectors or by reducing the volume of detector exposed to the flux. We describe a novel method of avoiding saturation by optically controlling the number neutron events processed by the detector electronics. Because of the optical opacity of the ZnS-plastic detectors such as NE451, photons from a proton-recoil scintillation arise from a spatially localized area of the detector. By imaging a selected portion of the detector onto a photomultiplier, we reduce the effective volume of the detector in a controllable, reversible way. A prototype system, consisting of a focusing lens, a field lens, and a variable aperture, has been constructed. Results of laboratory feasibility tests are presented

Timing and position response of a block detector for fast neutron time-of-flight imaging

Energy Technology Data Exchange (ETDEWEB)

Laubach, M.A., E-mail: mlaubach@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Hayward, J.P., E-mail: jhayward@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Zhang, X., E-mail: xzhang39@utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Cates, J.W., E-mail: jcates7@vols.utk.edu [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

2014-11-01

Our research effort seeks to improve the spatial and timing performance of a block detector made of a pixilated plastic scintillator (EJ-200), first demonstrated as part of Oak Ridge National Laboratory's Advanced Portable Neutron Imaging System. Improvement of the position and time response is necessary to achieve better resolution and contrast in the images of shielded special nuclear material. Time-of-flight is used to differentiate between gamma and different sources of neutrons (e.g., transmission and fission neutrons). Factors limiting the timing and position performance of the neutron detector have been revealed through simulations and measurements. Simulations have suggested that the degradation in the ability to resolve pixels in the neutron detector is due to those interactions occurring near the light guide. The energy deposition within the neutron detector is shown to affect position performance and imaging efficiency. This examination details how energy cuts improve the position performance and degrade the imaging efficiency. Measurements have shown the neutron detector to have a timing resolution of σ=238 ps. The majority of this timing uncertainty is from the depth-of-interaction (DOI) of the neutron which is confirmed by simulations and analytical calculations.

WE-DE-207B-01: Optimization for Contrast-Enhanced Spectral Mammography Based On Photon-Counting Detectors

Energy Technology Data Exchange (ETDEWEB)

Ding, H; Molloi, S [University of California, Irvine, CA (United States)

2016-06-15

Purpose: To investigate the feasibility of optimizing the imaging parameters for contrast-enhanced spectral mammography based on Si strip photon-counting detectors. Methods: A computer simulation model using polyenergetic spectra from a tungsten anode x-ray tube and a Si-based photon-counting detector was evaluated for contrast-enhanced spectral mammography. The simulation traces the emission of photons from the x-ray source, attenuation through the breast and subsequent absorption in the detector. The breast was modeled as a mixture of adipose and mammary gland tissues with a breast density of 30%. A 4 mm iodine signal with a concentration of 4 mg/ml was used to simulate the enhancement of a lesion. Quantum efficiency of the detector was calculated based on the effective attenuation length in the Si strips. The figure-of-merit (FOM), which was defined as the decomposed iodine signal-to-noise ratio (SNR) with respect to the square root of the mean glandular dose (MGD), was chosen to optimize the imaging parameters, in terms of beam energy, splitting energy, and pre-filtrations for breast of various thicknesses and densities. Results: The optimal imaging parameters, which lead to the highest FOM, were found at a beam energy of 45 kVp with a splitting energy at 34 keV for an averaged breast thickness of 4 cm with a standard 0.75 mm Al pre-filtration. The optimal tube voltage varied slightly from 46 to 44 kVp as the breast thickness increases from 2 to 8 cm. The optimal tube voltage decreased to 42 kVp when the Al pre-filtration was increased to 3 mm. Conclusion: This simulation study predicted the optimal imaging parameters for application of photon-counting spectral mammography to contrast-enhanced imaging. The simulation results laid the ground work for future phantom and clinical studies. Grant funding from Philips Medical Systems.

Electron imaging with Medipix2 hybrid pixel detector

International Nuclear Information System (INIS)

McMullan, G.; Cattermole, D.M.; Chen, S.; Henderson, R.; Llopart, X.; Summerfield, C.; Tlustos, L.; Faruqi, A.R.

2007-01-01

The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 μmx55 μm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 μm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach ∼85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach ∼35% of that expected for a perfect detector (4/π 2 ). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/π). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses

Electron imaging with Medipix2 hybrid pixel detector.

Science.gov (United States)

McMullan, G; Cattermole, D M; Chen, S; Henderson, R; Llopart, X; Summerfield, C; Tlustos, L; Faruqi, A R

2007-01-01

The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 microm x 55 microm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 microm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach approximately 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach approximately 35% of that expected for a perfect detector (4/pi(2)). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/pi). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses.

TU-E-BRA-05: Reverse Geometry Imaging with MV Detector for Improved Image Resolution.

Science.gov (United States)

Ganguly, A; Abel, E; Sun, M; Fahrig, R; Virshup, G; Star-Lack, J

2012-06-01

Thick pixilated scintillators can offer significant improvements in quantum efficiency over phosphor screen megavoltage (MV) detectors. However spatial resolution can be compromised due to the spreading of light across pixels within septa. Of particular interest are the lower energy x-ray photons and associated light photons that produce higher image contrast but are stopped near the scintillator entrance surface. They suffer the most scattering in the scintillator prior to detection in the photodiodes. Reversing the detector geometry, so that the incident x-ray beam passes through the photodiode array into the scintillator, allows the light to scatter less prior to detection. This also reduces the Swank noise since now higher and lower energy x-ray photons tend to produce similar electronic signals. In this work, we present simulations and measurements of detector MTF for the conventional/forward and reverse geometries to demonstrate this phenomenon. A tabletop system consisting of a Varian CX1 1MeV linear accelerator and a modified Varian Paxscan4030 with the readout electronics moved away from the incident the beam was used. A special holder was used to press a 2.5W×5.0L×2.0Hcm 3 pixellated Cesium Iodide (CsI:Tl) scintillator array on to the detector glass. The CsI array had a pitch of 0.784mm with plastic septa between pixels and the photodiode array pitch was 0.192 mm. The MTF in the forward and reverse geometries was measured using a 0.5mm thick Tantalum slanted edge. Geant4-based Monte Carlo simulations were performed for comparison. The measured and simulated MTFs matched to within 3.4(±3.7)% in the forward and 4.4(±1.5)% in reverse geometries. The reverse geometry MTF was higher than the forward geometry MTF at all spatial frequencies and doubled to .25 at 0.3lp/mm. A novel method of improving the image resolution at MV energies was demonstrated. The improvements should be more pronounced with increased scintillator thickness. Funding support provided

Maximum likelihood positioning for gamma-ray imaging detectors with depth of interaction measurement

International Nuclear Information System (INIS)

Lerche, Ch.W.; Ros, A.; Monzo, J.M.; Aliaga, R.J.; Ferrando, N.; Martinez, J.D.; Herrero, V.; Esteve, R.; Gadea, R.; Colom, R.J.; Toledo, J.; Mateo, F.; Sebastia, A.; Sanchez, F.; Benlloch, J.M.

2009-01-01

The center of gravity algorithm leads to strong artifacts for gamma-ray imaging detectors that are based on monolithic scintillation crystals and position sensitive photo-detectors. This is a consequence of using the centroids as position estimates. The fact that charge division circuits can also be used to compute the standard deviation of the scintillation light distribution opens a way out of this drawback. We studied the feasibility of maximum likelihood estimation for computing the true gamma-ray photo-conversion position from the centroids and the standard deviation of the light distribution. The method was evaluated on a test detector that consists of the position sensitive photomultiplier tube H8500 and a monolithic LSO crystal (42mmx42mmx10mm). Spatial resolution was measured for the centroids and the maximum likelihood estimates. The results suggest that the maximum likelihood positioning is feasible and partially removes the strong artifacts of the center of gravity algorithm.

Maximum likelihood positioning for gamma-ray imaging detectors with depth of interaction measurement

Energy Technology Data Exchange (ETDEWEB)

Lerche, Ch.W. [Grupo de Sistemas Digitales, ITACA, Universidad Politecnica de Valencia, 46022 Valencia (Spain)], E-mail: lerche@ific.uv.es; Ros, A. [Grupo de Fisica Medica Nuclear, IFIC, Universidad de Valencia-Consejo Superior de Investigaciones Cientificas, 46980 Paterna (Spain); Monzo, J.M.; Aliaga, R.J.; Ferrando, N.; Martinez, J.D.; Herrero, V.; Esteve, R.; Gadea, R.; Colom, R.J.; Toledo, J.; Mateo, F.; Sebastia, A. [Grupo de Sistemas Digitales, ITACA, Universidad Politecnica de Valencia, 46022 Valencia (Spain); Sanchez, F.; Benlloch, J.M. [Grupo de Fisica Medica Nuclear, IFIC, Universidad de Valencia-Consejo Superior de Investigaciones Cientificas, 46980 Paterna (Spain)

2009-06-01

The center of gravity algorithm leads to strong artifacts for gamma-ray imaging detectors that are based on monolithic scintillation crystals and position sensitive photo-detectors. This is a consequence of using the centroids as position estimates. The fact that charge division circuits can also be used to compute the standard deviation of the scintillation light distribution opens a way out of this drawback. We studied the feasibility of maximum likelihood estimation for computing the true gamma-ray photo-conversion position from the centroids and the standard deviation of the light distribution. The method was evaluated on a test detector that consists of the position sensitive photomultiplier tube H8500 and a monolithic LSO crystal (42mmx42mmx10mm). Spatial resolution was measured for the centroids and the maximum likelihood estimates. The results suggest that the maximum likelihood positioning is feasible and partially removes the strong artifacts of the center of gravity algorithm.

Evaluation of scintillators and semiconductor detectors to image three-photon positron annihilation for positron emission tomography

International Nuclear Information System (INIS)

Abuelhia, E.; Spyrou, N.M.; Kacperski, K.; College University, Middlesex Hospital, London

2008-01-01

Positron emission tomography (PET) is rapidly becoming the main nuclear imaging modality of the present century. The future of PET instrumentation relies on semiconductor detectors because of their excellent characteristics. Three-photon positron annihilation has been recently investigated as a novel imaging modality, which demands the crucial high energy resolution of semiconductor detector. In this work the evaluation of the NaI(Tl) scintillator and HPGe and CdZTe semiconductor detectors, to construct a simple three-photon positron annihilation scanner has been explored. The effect of detector and scanner size on spatial resolution (FWHM) is discussed. The characteristics: energy resolution versus count rate and point-spread function of the three-photon positron annihilation image profile from triple coincidence measurements were investigated. (author)

Trade off study on different envelope detectors for B-mode imaging

DEFF Research Database (Denmark)

Schlaikjer, Malene; Bagge, J. P.; Jensen, Jørgen Arendt

2003-01-01

sum of the real and imaginary signals. The four detectors were evaluated on in-vivo data acquired with a B-K Medical 2102 scanner interfaced to the sampling system RASMINE. Three data sets were acquired with three different center frequencies. Hundred images were acquired as the transducer was moved......Generation of B-mode images involves envelope detection of the RF-signals. Various detection algorithms are available. A trade off between performance, price, and complexity determines the choice of algorithm in an ultrasound system. A Hilbert Transform (HT) and a subsequent computation...... of the magnitude give the ideal envelope, but the approach (IDE) is expensive and complex. A rectifier (REC) is a simple, low-cost solution, but the performance is severely degraded (especially in dynamic imaging). This study has investigated the possibility of providing a detector with a complexity and cost close...

3-D Spatial Resolution of 350 μm Pitch Pixelated CdZnTe Detectors for Imaging Applications.

Science.gov (United States)

Yin, Yongzhi; Chen, Ximeng; Wu, Heyu; Komarov, Sergey; Garson, Alfred; Li, Qiang; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2013-02-01

We are currently investigating the feasibility of using highly pixelated Cadmium Zinc Telluride (CdZnTe) detectors for sub-500 μ m resolution PET imaging applications. A 20 mm × 20 mm × 5 mm CdZnTe substrate was fabricated with 350 μ m pitch pixels (250 μ m anode pixels with 100 μ m gap) and coplanar cathode. Charge sharing among the pixels of a 350 μ m pitch detector was studied using collimated 122 keV and 511 keV gamma ray sources. For a 350 μ m pitch CdZnTe detector, scatter plots of the charge signal of two neighboring pixels clearly show more charge sharing when the collimated beam hits the gap between adjacent pixels. Using collimated Co-57 and Ge-68 sources, we measured the count profiles and estimated the intrinsic spatial resolution of 350 μ m pitch detector biased at -1000 V. Depth of interaction was analyzed based on two methods, i.e., cathode/anode ratio and electron drift time, in both 122 keV and 511 keV measurements. For single-pixel photopeak events, a linear correlation between cathode/anode ratio and electron drift time was shown, which would be useful for estimating the DOI information and preserving image resolution in CdZnTe PET imaging applications.

Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

Science.gov (United States)

Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

2014-01-01

Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

New developments in PET detector technology

International Nuclear Information System (INIS)

Niu Lingxin; Zhao Shujun; Zhang Bin; Liu Haojia

2010-01-01

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

Modeling and design of X-rays bidimensional detectors; Modelagem e projeto de detectores bidimensionais para radiacao-X

Energy Technology Data Exchange (ETDEWEB)

Quisbert, Elmer Paz Alcon

2000-03-01

In this work has been developed the scintillating fiber optic and semiconductor devices based 2-D detector design, modeling and performance evaluation using Monte Carlo methods, for high X-ray energy range (10-140 kV) radiography and tomography applications. These processes allowed us, also, the imaging system parameters and components optimization and appropriate detector design. The model estimated the detectors performance parameters (DQE, MTF and SNR), and radiation risk (in terms of mean absorbed dose in the patient) and to show up how the sequence of physical processes in X-ray detection influence the performance of this imaging PFOC detectors. In this way, the modeling of the detector includes the statistics of the spatial distribution of absorbed X-rays and of X-ray to light conversion, its transmission, and the light quanta conversion into electrons. Also contributions to noise from the detection system chain is included, mainly the CCD detector ambient noise. Performance prediction, based on calculation taken from simulations, illustrates how such detectors meet the exacting requirements of some medical and industrial applications. Also, it is envisaged that our modeling procedure of the imaging system will be suitable not only for investigating how the system components should be best designed but for CT and RD system performance prediction. The powerful techniques would enable us to give advice for future development, in this field, in search of more dose-efficient imaging systems. (author)

Edge-based compression of cartoon-like images with homogeneous diffusion

DEFF Research Database (Denmark)

Mainberger, Markus; Bruhn, Andrés; Weickert, Joachim

2011-01-01

Edges provide semantically important image features. In this paper a lossy compression method for cartoon-like images is presented, which is based on edge information. Edges together with some adjacent grey/colour values are extracted and encoded using a classical edge detector, binary compressio...

Radiography imaging by 64 and 128 micro-strips crystalline detectors at different X-ray energies

International Nuclear Information System (INIS)

Leyva, A.; Cabal, A.; Montano, L. M.; Fontaine, M.; Mora, R. de la; Padilla, F.

2006-01-01

This paper summarizes some results obtained in the evaluation of the performance of position sensitive detectors in track reconstruction in particle physics experiments. Crystalline silicon micro-strips detectors with 64 and 128 channels and 100 μm pitch were used to obtain radiographic digital images of different objects. The more relevant figures for spectrometry applications were measured and reported. Two-dimensional images were obtained by scanning the object with a collimated beam using different source-target-detector positioning and three sources of X-rays (8.04, 18.55 and 22.16 keV). The counts acquired by each strip correspond to a particular collimator position during the scan, thus serving to reconstruct the image of the exposed to X-ray object and to reveal its internal structure. The use of some techniques for image processing allow the further improvement of the radiography quality. The preliminary results obtained using in-house made and accreditation mammography phantoms allow to infer that such detectors can be successfully introduced in the digital mammography practice. (Author)

Mercuric iodide room-temperature array detectors for gamma-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Patt, B. [Xsirius, Inc, Camarillo, CA (United States)

1994-11-15

Significant progress has been made recently in the development of mercuric iodide detector arrays for gamma-ray imaging, making real the possibility of constructing high-performance small, light-weight, portable gamma-ray imaging systems. New techniques have been applied in detector fabrication and then low noise electronics which have produced pixel arrays with high-energy resolution, high spatial resolution, high gamma stopping efficiency. Measurements of the energy resolution capability have been made on a 19-element protypical array. Pixel energy resolutions of 2.98% fwhm and 3.88% fwhm were obtained at 59 keV (241-Am) and 140-keV (99m-Tc), respectively. The pixel spectra for a 14-element section of the data is shown together with the composition of the overlapped individual pixel spectra. These techniques are now being applied to fabricate much larger arrays with thousands of pixels. Extension of these principles to imaging scenarios involving gamma-ray energies up to several hundred keV is also possible. This would enable imaging of the 208 keV and 375-414 keV 239-Pu and 240-Pu structures, as well as the 186 keV line of 235-U.

Calibration of Cherenkov detectors for monoenergetic photon imaging in active interrogation applications

Energy Technology Data Exchange (ETDEWEB)

Rose, P.B., E-mail: prose6@gatech.edu; Erickson, A.S., E-mail: anna.erickson@me.gatech.edu

2015-11-01

Active interrogation of cargo containers using monoenergetic photons offers a rapid and low-dose approach to search for shielded special nuclear materials. Cherenkov detectors can be used for imaging of the cargo provided that gamma ray energies used in interrogation are well resolved, as the case in {sup 11}B(d,n-γ){sup 12}C reaction resulting in 4.4 MeV and 15.1 MeV photons. While an array of Cherenkov threshold detectors reduces low energy background from scatter while providing the ability of high contrast transmission imaging, thus confirming the presence of high-Z materials, these detectors require a special approach to energy calibration due to the lack of resolution. In this paper, we discuss the utility of Cherenkov detectors for active interrogation with monoenergetic photons as well as the results of computational and experimental studies of their energy calibration. The results of the studies with sources emitting monoenergetic photons as well as complex gamma ray spectrum sources, for example {sup 232}Th, show that calibration is possible as long as the energies of photons of interest are distinct.

A digital data acquisition scheme for SPECT and PET small animal imaging detectors for Theranostic applications

Science.gov (United States)

Georgiou, M.; Fysikopoulos, E.; Loudos, G.

2017-11-01

Nanoparticle based drug delivery is considered as a new, promising technology for the efficient treatment of various diseases. When nanoparticles are radiolabelled it is possible to image them, using molecular imaging techniques. The use of magnetic nanoparticles in hyperthermia is one of the most promising nanomedicine directions and requires the accurate, non-invasive, monitoring of temperature increase and drug release. The combination of imaging and therapy has opened the very promising Theranostics domain. In this work, we present a digital data acquisition scheme for nuclear medicine dedicated detectors for Theranostic applications.

Gas scintillation glass GEM detector for high-resolution X-ray imaging and CT

Energy Technology Data Exchange (ETDEWEB)

Fujiwara, T., E-mail: fujiwara-t@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Mitsuya, Y. [Nuclear Professional School, The University of Tokyo, Tokai, Naka, Ibaraki 319-1188 (Japan); Fushie, T. [Radiment Lab. Inc., Setagaya, Tokyo 156-0044 (Japan); Murata, K.; Kawamura, A.; Koishikawa, A. [XIT Co., Naruse, Machida, Tokyo 194-0045 (Japan); Toyokawa, H. [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Takahashi, H. [Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8654 (Japan)

2017-04-01

A high-spatial-resolution X-ray-imaging gaseous detector has been developed with a single high-gas-gain glass gas electron multiplier (G-GEM), scintillation gas, and optical camera. High-resolution X-ray imaging of soft elements is performed with a spatial resolution of 281 µm rms and an effective area of 100×100 mm. In addition, high-resolution X-ray 3D computed tomography (CT) is successfully demonstrated with the gaseous detector. It shows high sensitivity to low-energy X-rays, which results in high-contrast radiographs of objects containing elements with low atomic numbers. In addition, the high yield of scintillation light enables fast X-ray imaging, which is an advantage for constructing CT images with low-energy X-rays.

Assessment of array scintillation detector for follicle thyroid 2-d image acquisition using Monte Carlo simulation

International Nuclear Information System (INIS)

Silva, Carlos Borges da; Braz, Delson

2008-01-01

Full text: This work presents an innovative study to find out the adequate scintillation inorganic detector array to be used coupled to a specific light photo sensor, a charge coupled device (CCD), through a fiber optic plate. The goal is to choose the type of detector that fits a 2-dimensional imaging acquisition of a cell thyroid tissue application with high resolution and detection efficiency in order to map a follicle image using gamma radiation emission. A point or volumetric source-detector simulation by using a MCNP4B general code, considering different source energies, detector materials and geometry including pixel sizes and reflector types was performed. In this study, simulations were performed for 7 x 7, 31 x 31 and 127 x 127 arrays using CsI(Tl), BGO, CdWO 4 , LSO, GOS and GSO scintillation detectors with pixel dimensions ranging from 1 x 1 cm 2 to 10 x 10 μm 2 and radiation thickness ranging from 1 mm to 10 mm. The effect of all these parameters was investigated to find the best source-detector system that results in an image with the best contrast details. The results showed that it is possible to design a specific imaging system that allows searching for in-vitro studies, specifically in radiobiology applied to endocrine physiology. A 2D image of two thyroid follicles simulated by using MCNP4B code is shown

Electrically-cooled HPGe detector for advanced x-ray spectroscopy and imaging

Energy Technology Data Exchange (ETDEWEB)

Marian, V.; Clauss, J.; Pirard, B.; Quirin, P.; Flamanc, J.; Lampert, M.O. [CANBERRA France, Parc des Tanneries, 1, chemin de la roseraie, 67380 Lingolsheim (France)

2015-07-01

High Purity Germanium (HPGe) detectors are used for high-resolution x- and gamma-ray spectroscopy. For their operation, the necessary cryogenic cooling is performed with liquid nitrogen or with electromechanical coolers. Although mature and industrialized solutions, most of HPGe detectors integrating electrical coolers present a limited spectroscopic performance due to the generated mechanical vibration and electromagnetic interference. This paper describes a novel HPGe detector, specifically designed to address the challenges of ultimate x-ray spectroscopy and imaging applications. Due to the stringent demands associated with nano-scale imaging in synchrotron applications, a custom-designed cryostat was built around a Canberra CP5-Plus electrical cooler featuring extremely low vibration levels and high cooling power. The heat generated by the cryo-cooler itself, as well as the electronics, is evacuated via an original liquid cooling circuit. This architecture can also be used to address high ambient temperature, which does not allow conventional cryo-coolers to work properly. The multichannel detector head can consist of a segmented monolithic HPGe sensor, or several closely packed sensors. Each sensor channel is read out by state-of-the-art pulse-reset preamplifiers in order to achieve excellent energy resolution for count rates in excess of 1 Mcps. The sensitive electronics are located in EMI-proof housings to avoid any interference from other devices on a beam-line. The front-end of the detector is built using selected high-purity materials and alloys to avoid any fluorescence effects. We present a detailed description of the detector design and we report on its performance. A discussion is also given on the use of electrically cooled HPGe detectors for applications requiring ultimate energy resolution, such as synchrotron, medicine or nuclear industry. (authors)

Web-based, GPU-accelerated, Monte Carlo simulation and visualization of indirect radiation imaging detector performance.

Science.gov (United States)

Dong, Han; Sharma, Diksha; Badano, Aldo

2014-12-01

Monte Carlo simulations play a vital role in the understanding of the fundamental limitations, design, and optimization of existing and emerging medical imaging systems. Efforts in this area have resulted in the development of a wide variety of open-source software packages. One such package, hybridmantis, uses a novel hybrid concept to model indirect scintillator detectors by balancing the computational load using dual CPU and graphics processing unit (GPU) processors, obtaining computational efficiency with reasonable accuracy. In this work, the authors describe two open-source visualization interfaces, webmantis and visualmantis to facilitate the setup of computational experiments via hybridmantis. The visualization tools visualmantis and webmantis enable the user to control simulation properties through a user interface. In the case of webmantis, control via a web browser allows access through mobile devices such as smartphones or tablets. webmantis acts as a server back-end and communicates with an NVIDIA GPU computing cluster that can support multiuser environments where users can execute different experiments in parallel. The output consists of point response and pulse-height spectrum, and optical transport statistics generated by hybridmantis. The users can download the output images and statistics through a zip file for future reference. In addition, webmantis provides a visualization window that displays a few selected optical photon path as they get transported through the detector columns and allows the user to trace the history of the optical photons. The visualization tools visualmantis and webmantis provide features such as on the fly generation of pulse-height spectra and response functions for microcolumnar x-ray imagers while allowing users to save simulation parameters and results from prior experiments. The graphical interfaces simplify the simulation setup and allow the user to go directly from specifying input parameters to receiving visual

Bolometric kinetic inductance detector technology for sub-millimeter radiometric imaging

Science.gov (United States)

Hassel, Juha; Timofeev, Andrey V.; Vesterinen, Visa; Sipola, Hannu; Helistö, Panu; Aikio, Mika; Mäyrä, Aki; Grönberg, Leif; Luukanen, Arttu

2015-10-01

Radiometric sub-millimeter imaging is a candidate technology especially in security screening applications utilizing the property of radiation in the band of 0.2 - 1.0 THz to penetrate through dielectric substances such as clothing. The challenge of the passive technology is the fact that the irradiance corresponding to the blackbody radiation is very weak in this spectral band: about two orders of magnitude below that of the infrared band. Therefore the role of the detector technology is of ultimate importance to achieve sufficient sensitivity. In this paper we present results related to our technology relying on superconducting kinetic inductance detectors operating in a thermal (bolometric) mode. The detector technology is motivated by the fact that it is naturally suitable for scalable multiplexed readout systems, and operates with relatively simple cryogenics. We will review the basic concepts of the detectors, and provide experimental figures of merit. Furthermore, we will discuss the issues related to the scale-up of our detector technology into large 2D focal plane arrays.

Position sensitive detector with semiconductor and image electron tube comprising such a detector

International Nuclear Information System (INIS)

Roziere, Guy.

1977-01-01

This invention concerns a position sensitive detector comprising a semiconducting substrate. It also concerns the electron tubes in which the detector may be incorporated in order to obtain an image formed at the tube input by an incident flux of particles or radiation. When a charged particle or group of such particles, electrons in particular, enter the space charge region of an inversely biased semiconductor diode, the energy supplied by these particles releases in the diode a certain number of electron-hole pairs which move in the field existing in the area towards the diode contacts. A corresponding current arises in the connections of this diode which constitutes the signal corresponding to the incident energy. Such a tube or chain of tubes is employed in nuclear medicine for observing parts of the human body, particularly by gamma radiation [fr

Semiconductor detectors with proximity signal readout

International Nuclear Information System (INIS)

Asztalos, Stephen J.

2012-01-01

Semiconductor-based radiation detectors are routinely used for the detection, imaging, and spectroscopy of x-rays, gamma rays, and charged particles for applications in the areas of nuclear and medical physics, astrophysics, environmental remediation, nuclear nonproliferation, and homeland security. Detectors used for imaging and particle tracking are more complex in that they typically must also measure the location of the radiation interaction in addition to the deposited energy. In such detectors, the position measurement is often achieved by dividing or segmenting the electrodes into many strips or pixels and then reading out the signals from all of the electrode segments. Fine electrode segmentation is problematic for many of the standard semiconductor detector technologies. Clearly there is a need for a semiconductor-based radiation detector technology that can achieve fine position resolution while maintaining the excellent energy resolution intrinsic to semiconductor detectors, can be fabricated through simple processes, does not require complex electrical interconnections to the detector, and can reduce the number of required channels of readout electronics. Proximity electrode signal readout (PESR), in which the electrodes are not in physical contact with the detector surface, satisfies this need

Sparse Detector Imaging Sensor with Two-Class Silhouette Classification

Directory of Open Access Journals (Sweden)

David Russomanno

2008-12-01

Full Text Available This paper presents the design and test of a simple active near-infrared sparse detector imaging sensor. The prototype of the sensor is novel in that it can capture remarkable silhouettes or profiles of a wide-variety of moving objects, including humans, animals, and vehicles using a sparse detector array comprised of only sixteen sensing elements deployed in a vertical configuration. The prototype sensor was built to collect silhouettes for a variety of objects and to evaluate several algorithms for classifying the data obtained from the sensor into two classes: human versus non-human. Initial tests show that the classification of individually sensed objects into two classes can be achieved with accuracy greater than ninety-nine percent (99% with a subset of the sixteen detectors using a representative dataset consisting of 512 signatures. The prototype also includes a Webservice interface such that the sensor can be tasked in a network-centric environment. The sensor appears to be a low-cost alternative to traditional, high-resolution focal plane array imaging sensors for some applications. After a power optimization study, appropriate packaging, and testing with more extensive datasets, the sensor may be a good candidate for deployment in vast geographic regions for a myriad of intelligent electronic fence and persistent surveillance applications, including perimeter security scenarios.

Fluorescence decay time imaging using an imaging photon detector with a radio frequency photon correlation system

Science.gov (United States)

Morgan, Christopher G.; Mitchell, A. C.; Murray, J. G.

1990-05-01

An imaging photon detector has been modified to incorporate fast timing electronics coupled to a custom built photon correlator interfaced to a RISC computer. Using excitation with intensity- muodulated light, fluorescence images can be readily obtained where contrast is determined by the decay time of emission, rather than by intensity. This technology is readily extended to multifrequency phase/demodulation fluorescence imaging or to differential polarised phase fluorometry. The potential use of the correlator for confocal imaging with a laser scanner is also briefly discussed.

Properties of thick GEM in low-pressure deuterium

International Nuclear Information System (INIS)

Lee, C S; Ota, S; Tokieda, H; Kojima, R; Watanabe, Y N; Uesaka, T

2014-01-01

Deuteron inelastic scattering (d, d') provides a promising spectroscopic tool to study nuclear incompressibility. In studies of deuteron inelastic scattering of unstable nuclei, measurements of low-energy recoiled particles is very important. In order to perform these measurements, we are developing a GEM-TPC based gaseous active target, called CAT (Center for nuclear study Active Target), operated with pure deuterium gas. The CAT has been tested with deuterium gas at 1 atm and 100-μm-thick GEMs. The low-pressure operation of CAT is planned in order to improve the detection capability for lower-energy recoil particles. A 400 μm-thick gas electron multiplier (THGEM) was chosen for the low-pressure operation of CAT. However, the properties of THGEM in low-pressure deuterium are currently undocumented. In this work, the performance of THGEM with low-pressure pure deuterium gas has been investigated. The effective gas gain of THGEM has been measured in various conditions using a 5.5-MeV 241 Am alpha source. The effective gas gain was measured for 0.2-, 0.3- and 0.4-atm deuterium gas and a gas gain of about 10 3 was achieved by a double THGEM structure at 0.2 atm. The maximum achieved gain decreased with increasing gas pressure. The dependences of the effective gas gain on the electric field strengths of the drift, transfer and induction regions were investigated. The gain stability as a function of time in hydrogen gas was also tested and a relaxation time of THGEM of about 60 hours was observed with a continuous irradiation of alpha particles, which is significantly longer than previous studies have reported. We have tried to evaluate the gas gain of THGEM in deuterium gas by considering only the Townsend ionization process; however, it turned out that more phenomenological aspects, such as transfer efficiency, should be included in the evaluation. The basic properties of THGEM in low-pressure deuterium have been investigated for the first time

Properties of thick GEM in low-pressure deuterium

Science.gov (United States)

Lee, C. S.; Ota, S.; Tokieda, H.; Kojima, R.; Watanabe, Y. N.; Uesaka, T.

2014-05-01

Deuteron inelastic scattering (d, d') provides a promising spectroscopic tool to study nuclear incompressibility. In studies of deuteron inelastic scattering of unstable nuclei, measurements of low-energy recoiled particles is very important. In order to perform these measurements, we are developing a GEM-TPC based gaseous active target, called CAT (Center for nuclear study Active Target), operated with pure deuterium gas. The CAT has been tested with deuterium gas at 1 atm and 100-μm-thick GEMs. The low-pressure operation of CAT is planned in order to improve the detection capability for lower-energy recoil particles. A 400 μm-thick gas electron multiplier (THGEM) was chosen for the low-pressure operation of CAT. However, the properties of THGEM in low-pressure deuterium are currently undocumented. In this work, the performance of THGEM with low-pressure pure deuterium gas has been investigated. The effective gas gain of THGEM has been measured in various conditions using a 5.5-MeV 241Am alpha source. The effective gas gain was measured for 0.2-, 0.3- and 0.4-atm deuterium gas and a gas gain of about 103 was achieved by a double THGEM structure at 0.2 atm. The maximum achieved gain decreased with increasing gas pressure. The dependences of the effective gas gain on the electric field strengths of the drift, transfer and induction regions were investigated. The gain stability as a function of time in hydrogen gas was also tested and a relaxation time of THGEM of about 60 hours was observed with a continuous irradiation of alpha particles, which is significantly longer than previous studies have reported. We have tried to evaluate the gas gain of THGEM in deuterium gas by considering only the Townsend ionization process; however, it turned out that more phenomenological aspects, such as transfer efficiency, should be included in the evaluation. The basic properties of THGEM in low-pressure deuterium have been investigated for the first time.

Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging

International Nuclear Information System (INIS)

Schmidgunst, C.; Ritter, D.; Lang, E.

2007-01-01

The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology

High-resolution 3D laser imaging based on tunable fiber array link

Science.gov (United States)

Zhao, Sisi; Ruan, Ningjuan; Yang, Song

2017-10-01

Airborne photoelectric reconnaissance system with the bore sight down to the ground is an important battlefield situational awareness system, which can be used for reconnaissance and surveillance of complex ground scene. Airborne 3D imaging Lidar system is recognized as the most potential candidates for target detection under the complex background, and is progressing in the directions of high resolution, long distance detection, high sensitivity, low power consumption, high reliability, eye safe and multi-functional. However, the traditional 3D laser imaging system has the disadvantages of lower imaging resolutions because of the small size of the existing detector, and large volume. This paper proposes a high resolution laser 3D imaging technology based on the tunable optical fiber array link. The echo signal is modulated by a tunable optical fiber array link and then transmitted to the focal plane detector. The detector converts the optical signal into electrical signals which is given to the computer. Then, the computer accomplishes the signal calculation and image restoration based on modulation information, and then reconstructs the target image. This paper establishes the mathematical model of tunable optical fiber array signal receiving link, and proposes the simulation and analysis of the affect factors on high density multidimensional point cloud reconstruction.

Added value of integrated circuit detector in head CT: objective and subjective image quality in comparison to conventional detector design.

Science.gov (United States)

Korn, Andreas; Bender, Benjamin; Spira, Daniel; Schabel, Christoph; Bhadelia, Rafeeque; Claussen, Claus; Ernemann, Ulrike; Brodoefel, Harald

2014-12-01

A new computed tomography (CT) detector with integrated electric components and shorter conducting pathways has recently been introduced to decrease system inherent electronic noise. The purpose of this study was to assess the potential benefit of such integrated circuit detector (ICD) in head CT by comparing objective and subjective image quality in low-dose examinations with a conventional detector design. Using a conventional detector, reduced-dose noncontrast head CT (255 mAs; effective dose, 1.7 mSv) was performed in 25 consecutive patients. Following transition to ICD, 25 consecutive patients were scanned using identical imaging parameters. Images in both groups were reconstructed with iterative reconstruction (IR) and filtered back projection (FBP) and assessed in terms of quantitative and qualitative image quality. Acquisition of head CT using ICD increased signal-to-noise ratio of gray and white matter by 14% (10.0 ± 1.6 vs. 11.4 ± 2.5; P = .02) and 17% (8.2 ± 0.8 vs. 9.6 ± 1.5; P = .000). The associated improvement in contrast-to-noise ratio was 12% (2.0 ± 0.5 vs. 2.2 ± 0.6; P = .121). In addition, there was a 51% increase in objective image sharpness (582 ± 85 vs. 884.5 ± 191; change in HU/Pixel; P < .000). Compared to standard acquisitions, subjective grading of noise and overall image quality scores were significantly improved with ICD (2.1 ± 0.3 vs. 1.6 ± 0.3; P < .000; 2.0 ± 0.5 vs. 1.6 ± 0.3; P = .001). Moreover, streak artifacts in the posterior fossa were substantially reduced (2.3 ± 0.7 vs. 1.7 ± 0.5; P = .004). At the same radiation level, acquisition of head CT with ICD achieves superior objective and subjective image quality and provides potential for significant dose reduction. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

Performance of a thermal imager employing a hybrid pyroelectric detector array with MOSFET readout

International Nuclear Information System (INIS)

Watton, R.; Mansi, M.V.

1988-01-01

A thermal imager employing a two-dimensional hybrid array of pyroelectric detectors with MOSFET readout has been built. The design and theoretical performance of the detector are discussed, and the results of performance measurements are presented. 8 references

Current status of multi-detector row helical CT in imaging of adult ...

African Journals Online (AJOL)

Current status of multi-detector row helical CT in imaging of adult acquired pancreatic diseases and assessing surgical neoplastic resectability. ... The presence of inflammation, masses, and vascular invasion was evaluated and interpreted images were obtained during each phase. Results were compared with surgery, ...

Basis material decomposition method for material discrimination with a new spectrometric X-ray imaging detector

Science.gov (United States)

Brambilla, A.; Gorecki, A.; Potop, A.; Paulus, C.; Verger, L.

2017-08-01

Energy sensitive photon counting X-ray detectors provide energy dependent information which can be exploited for material identification. The attenuation of an X-ray beam as a function of energy depends on the effective atomic number Zeff and the density. However, the measured attenuation is degraded by the imperfections of the detector response such as charge sharing or pile-up. These imperfections lead to non-linearities that limit the benefits of energy resolved imaging. This work aims to implement a basis material decomposition method which overcomes these problems. Basis material decomposition is based on the fact that the attenuation of any material or complex object can be accurately reproduced by a combination of equivalent thicknesses of basis materials. Our method is based on a calibration phase to learn the response of the detector for different combinations of thicknesses of the basis materials. The decomposition algorithm finds the thicknesses of basis material whose spectrum is closest to the measurement, using a maximum likelihood criterion assuming a Poisson law distribution of photon counts for each energy bin. The method was used with a ME100 linear array spectrometric X-ray imager to decompose different plastic materials on a Polyethylene and Polyvinyl Chloride base. The resulting equivalent thicknesses were used to estimate the effective atomic number Zeff. The results are in good agreement with the theoretical Zeff, regardless of the plastic sample thickness. The linear behaviour of the equivalent lengths makes it possible to process overlapped materials. Moreover, the method was tested with a 3 materials base by adding gadolinium, whose K-edge is not taken into account by the other two materials. The proposed method has the advantage that it can be used with any number of energy channels, taking full advantage of the high energy resolution of the ME100 detector. Although in principle two channels are sufficient, experimental measurements show

Compton scatter in germanium and its effect on imaging with gamma-ray position-sensitive detectors

International Nuclear Information System (INIS)

Sherman, I.S.; Strauss, M.G.; Brenner, R.

1978-01-01

The spatial spread due to Compton scatter in Ge was measured to study the reduction in image contrast and signal-to-noise ratio (S/N) resulting from erroneous readout in Ge position-sensitive detectors. The step response revealing this spread was obtained by scanning with a 122 keV γ-ray beam across a boundary of two sectors of a slotted coaxial Ge(Li) detector that is 40 mm diameter by 22 mm long. The derived line-spread function at 140 keV (/sup 99m/Tc) exhibits much shorter but thicker tails than those due to scatter in tissue as observed with a NaI detector through 5.5 cm of scattering material. Convolutions of rectangular profiles of voids with the Ge(Li) line-spread function show marked deterioration in contrast for voids less than 10 mm across, which in turn results in even greater deterioration of the S/N. As a result, the contrast for voids in Ge images is only 20 to 30 percent higher than that in NaI and the S/N is only comparable for equal detector areas. The degradation in image contrast due to scatter in Ge detectors can be greatly reduced by either using thin detectors (approximately 5 mm), where scatter virtually does not exist, or by using thicker detectors and rejecting scatter electronically. To reduce the effects of scatter on the S/N as well as on contrast, the erroneous position readouts must actually be corrected. A more realizable approach to achieving the ultimate potential of Ge detectors may be a scanning array of discrete detectors (not position sensitive) in which readout is not affected by scatter

Automatic luminous reflections detector using global threshold with increased luminosity contrast in images

Science.gov (United States)

Silva, Ricardo Petri; Naozuka, Gustavo Taiji; Mastelini, Saulo Martiello; Felinto, Alan Salvany

2018-01-01

The incidence of luminous reflections (LR) in captured images can interfere with the color of the affected regions. These regions tend to oversaturate, becoming whitish and, consequently, losing the original color information of the scene. Decision processes that employ images acquired from digital cameras can be impaired by the LR incidence. Such applications include real-time video surgeries, facial, and ocular recognition. This work proposes an algorithm called contrast enhancement of potential LR regions, which is a preprocessing to increase the contrast of potential LR regions, in order to improve the performance of automatic LR detectors. In addition, three automatic detectors were compared with and without the employment of our preprocessing method. The first one is a technique already consolidated in the literature called the Chang-Tseng threshold. We propose two automatic detectors called adapted histogram peak and global threshold. We employed four performance metrics to evaluate the detectors, namely, accuracy, precision, exactitude, and root mean square error. The exactitude metric is developed by this work. Thus, a manually defined reference model was created. The global threshold detector combined with our preprocessing method presented the best results, with an average exactitude rate of 82.47%.

Real-time imaging systems for superconducting nanowire single-photon detector arrays

Energy Technology Data Exchange (ETDEWEB)

Hofherr, Matthias

2014-07-01

Superconducting nanowire singe-photon detectors (SNSPD) are promising detectors in the field of applications, where single-photon resolution is required like in quantum optics, spectroscopy or astronomy. These cryogenic detectors gain from a broad spectrum in the optical and infrared range and deliver low dark counts and low jitter. This work provides a piece of deeper physical understanding of detector functionality in combination with highly engineered readout development. A detailed analysis focuses on the intrinsic detection mechanism of SNSPDs related to the detection in the infrared regime and the evolution of dark counts. With this fundamental knowledge, the next step is the development of a multi-pixel readout at cryogenic conditions. It is demonstrated, how two auspicious multi-pixel readout concepts can be realized, which enables statistical framing like in imaging applications using RSFQ electronics with fast framing rates and the readout of a detector array with continuous real-time single-photon resolution.

Development of the microstrip silicon detector for imaging of fast processes at a synchrotron radiation beam

Energy Technology Data Exchange (ETDEWEB)

Aulchenko, V. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk, Russian Federtion (Russian Federation); Pruuel, E. [Lavrentiev Institute of Hydrodynamics, 630090 Novosibirsk, Russian Federtion (Russian Federation); Novosibirsk State University, 630090 Novosibirsk, Russian Federtion (Russian Federation); Shekhtman, L. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk, Russian Federtion (Russian Federation); Ten, K. [Lavrentiev Institute of Hydrodynamics, 630090 Novosibirsk, Russian Federtion (Russian Federation); Tolochko, B. [Institute of Solid State chemistry and Mechanochemistry, 630090 Novosibirsk, Russian Federtion (Russian Federation); Novosibirsk State University, 630090 Novosibirsk, Russian Federtion (Russian Federation); Zhulanov, V. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk, Russian Federtion (Russian Federation)

2017-02-11

In situ imaging of explosions allows to study material properties under very high pressures and temperatures. Synchrotron radiation (SR) is a powerful tool for such studies because of its unique time structure. Flashes of X-rays from individual bunches in a storage ring are so short that an object under study does not move more than 1–10 μm during exposure. If a detector is able to store images synchronously with bunches of an SR source the time resolution of such method will be determined by the duration of SR flash from individual bunch. New beam line at the VEPP-4M storage ring will allow to get X-Ray flux from each bunch close to 10{sup 6} photons/channel where channel area is 0.05×0.5 mm{sup 2} and average beam energy is about 30 keV. Bunches in the machine can be grouped into trains with 20 ns time gap. In order to meet these requirements a new detector development was started based on Si microstrip technology. The detector with a new dedicated front-end chip will be able to record images with maximum signal equivalent to 10{sup 6} photons/channel, with signal to noise ratio of ∼10{sup 3}, spatial resolution of 50 μm and maximum frame rate of 50 MHz. The detector has to drive very high peak and average currents without affecting the front-end chip, therefore a specific design of Si sensor should be developed. The front-end chip has to provide signal measurements with the dynamic range of about 10{sup 4} or more and recording of the signal to an analogue memory with the rate of 50 MHz. The concept of such detector is discussed in the paper. The results of the simulations of the main detector parameters and the results of the first measurements with the prototype sensors are presented.

Imaging with SiPMs in noble-gas detectors

International Nuclear Information System (INIS)

Yahlali, N; González, K; Fernandes, L M P; Garcia, A N C; Soriano, A

2013-01-01

Silicon photomultipliers (SiPMs) are photosensors widely used for imaging in a variety of high energy and nuclear physics experiments. In noble-gas detectors for double-beta decay and dark matter experiments, SiPMs are attractive photosensors for imaging. However they are insensitive to the VUV scintillation emitted by the noble gases (xenon and argon). This difficulty is overcome in the NEXT experiment by coating the SiPMs with tetraphenyl butadiene (TPB) to convert the VUV light into visible light. TPB requires stringent storage and operational conditions to prevent its degradation by environmental agents. The development of UV sensitive SiPMs is thus of utmost interest for experiments using electroluminescence of noble-gas detectors. It is in particular an important issue for a robust and background free ββ0ν experiment with xenon gas aimed by NEXT. The photon detection efficiency (PDE) of UV-enhanced SiPMs provided by Hamamatsu was determined for light in the range 250–500 nm. The PDE of standard SiPMs of the same model (S10362-33-50C), coated and non-coated with TPB, was also determined for comparison. In the UV range 250–350 nm, the PDE of the standard SiPM is shown to decrease strongly, down to about 3%. The UV-enhanced SiPM without window is shown to have the maximum PDE of 44% at 325 nm and 30% at 250 nm. The PDE of the UV-enhanced SiPM with silicon resin window has a similar trend in the UV range, although it is about 30% lower. The TPB-coated SiPM has shown to have about 6 times higher PDE than the non-coated SiPM in the range 250–315 nm. This is however below the performance of the UV-enhanced prototypes in the same wavelength range. Imaging in noble-gas detectors using UV-enhanced SiPMs is discussed.

Evaluation of In-Vacuum Imaging Plate Detector for X-Ray Diffraction Microscopy

International Nuclear Information System (INIS)

Nishino, Yoshinori; Takahashi, Yukio; Yamamoto, Masaki; Ishikawa, Tetsuya

2007-01-01

We performed evaluation tests of a newly developed in-vacuum imaging plate (IP) detector for x-ray diffraction microscopy. IP detectors have advantages over direct x-ray detection charge-coupled device (CCD) detectors, which have been commonly used in x-ray diffraction microscopy experiments, in the capabilities for a high photon count and for a wide area. The detector system contains two IPs to make measurement efficient by recording data with the one while reading or erasing the other. We compared speckled diffraction patterns of single particles taken with the IP and a direct x-ray detection CCD. The IP was inferior to the CCD in spatial resolution and in signal-to-noise ratio at a low photon count

ARIADNE: Beam Time and Resources Request - Addendum

CERN Document Server

Hollywood, D; Mavrokoridis, K; McCormick, KJ; Philippou, B; Roberts, A; Stavrakis, G; Touramanis, C; Vann, J

2017-01-01

This addendum provides additional information and clarification requested by the SPS Committee in response to our previously submitted Beam Time Request (CERN-SPSC-2017-031 [SPSC-P-356]). The ARIADNE research programme is based around developing an optical readout system for use in LAr TPC detectors, which could potentially have a number of benefits over the currently used segmented anode planes - particularly in matters of scalability for future kilo-tonne scale detectors, ease of installation, use and maintenance, and reconstruction resolution. As detailed in our previously submitted Letter of Intent (CERN-SPSC-2016-008 [SPSC-I-244]), ARIADNE itself is a 1-tonne, two-phase LAr TPC detector, designed and built at the University of Liverpool, which uses an array of EMCCD cameras as its optical readout system, alongside PMTs for scintillation light observation and a segmented THGEM for charge readout.

High-speed X-ray imaging pixel array detector for synchrotron bunch isolation.

Science.gov (United States)

Philipp, Hugh T; Tate, Mark W; Purohit, Prafull; Shanks, Katherine S; Weiss, Joel T; Gruner, Sol M

2016-03-01

A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8-12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10-100 ps) and intense X-ray pulses at megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. The characteristics, operation, testing and application of the detector are detailed.

The Omega Ring Imaging Cerenkov Detector readout system user's guide

International Nuclear Information System (INIS)

Hallewell, G.

1984-11-01

The manual describes the electronic readout system of the Ring Imaging Cerenkov Detector at the CERN Omega Spectrometer. The system is described in its configuration of September 1984 after the Rich readout system had been used in two Omega experiments. (U.K.)

Tiled Array of Pixelated CZT Imaging Detectors for ProtoEXIST2 and MIRAX-HXI

Science.gov (United States)

Hong, Jaesub; Allen, Branden; Grindlay, Jonathan; Rodrigues, Barbara; Ellis, Jon Robert; Baker, Robert; Barthelmy, Scott; Mao, Peter; Miyasaka, Hiromasa; Apple, Jeff

2013-12-01

We have assembled a tiled array (220 cm2) of fine pixel (0.6 mm) imaging CZT detectors for a balloon borne wide-field hard X-ray telescope, ProtoEXIST2. ProtoEXIST2 is a prototype experiment for a next generation hard X-ray imager MIRAX-HXI on board Lattes, a spacecraft from the Agencia Espacial Brasilieira. MIRAX will survey the 5 to 200 keV sky of Galactic bulge, adjoining southern Galactic plane and the extragalactic sky with 6 ' angular resolution. This survey will open a vast discovery space in timing studies of accretion neutron stars and black holes. The ProtoEXIST2 CZT detector plane consists of 64 of 5 mm thick 2 cm × 2 cm CZT crystals tiled with a minimal gap. MIRAX will consist of 4 such detector planes, each of which will be imaged with its own coded-aperture mask. We present the packaging architecture and assembly procedure of the ProtoEXIST2 detector. On 2012, Oct 10, we conducted a successful high altitude balloon experiment of the ProtoEXIST1 and 2 telescopes, which demonstrates their technology readiness for space application. During the flight both telescopes performed as well as on the ground. We report the results of ground calibration and the initial results for the detector performance in the balloon flight.

MHz rate X-Ray imaging with GaAs:Cr sensors using the LPD detector system

Science.gov (United States)

Veale, M. C.; Booker, P.; Cline, B.; Coughlan, J.; Hart, M.; Nicholls, T.; Schneider, A.; Seller, P.; Pape, I.; Sawhney, K.; Lozinskaya, A. D.; Novikov, V. A.; Tolbanov, O. P.; Tyazhev, A.; Zarubin, A. N.

2017-02-01

The STFC Rutherford Appleton Laboratory (U.K.) and Tomsk State University (Russia) have been working together to develop and characterise detector systems based on chromium-compensated gallium arsenide (GaAs:Cr) semiconductor material for high frame rate X-ray imaging. Previous work has demonstrated the spectroscopic performance of the material and its resistance to damage induced by high fluxes of X-rays. In this paper, recent results from experiments at the Diamond Light Source Synchrotron have demonstrated X-ray imaging with GaAs:Cr sensors at a frame rate of 3.7 MHz using the Large Pixel Detector (LPD) ASIC, developed by STFC for the European XFEL. Measurements have been made using a monochromatic 20 keV X-ray beam delivered in a single hybrid pulse with an instantenous flux of up to ~ 1 × 1010 photons s-1 mm-2. The response of 500 μm GaAs:Cr sensors is compared to that of the standard 500 μm thick LPD Si sensors.

16-slice multi-detector row CT coronary angiography: image quality and optimization of the image reconstruction window

International Nuclear Information System (INIS)

Kim, Yoo Kyung; Shim, Sung Shine; Lim, Soo Mee; Hwang, Ji Young; Kim, Yoon Kyung

2005-01-01

The purpose of this experiment is to investigate the image quality of CT coronary angiography using a 16-slice multi-detector row CT and to determine the optimal image reconstruction window. CT coronary angiography was obtained in 36 nonsymptomatic volunteers using a 16-slice multi-detector row CT (SOMATOM Sensation, Siemens Medical System). The mean heart rates were 70 beats per minute (bpm) or less in 18 persons and more than 70 bpm in 18 persons. Eleven data sets were obtained for each patient (reconstructed at 30%-80% of the cardiac cycle with an increment of 5%). Image quality of the eight coronary segments [left main coronary artery (LM), proximal and middle segments of left anterior descending artery (p-LAD, m-LAN) and left circumflex coronary artery (p-LCx, m-LCx) and proximal, middle and distal segments of right coronary artery (p-RCA, m-RCA, d-RCA)] was assessed. The optimal reconstruction windows in the cardiac cycle for the best image quality were 60-70% for the segments of the LM, LAD, and LC arteries in two groups (bpm 70) and 55-65% (bpm 70) for the segments of the RCA. On the best dataset for each coronary segment, the following diagnostic image quality was achieved in the two groups: LM: 100%, 83%; p-LAD: 100%, 88% m-LAD: 100%, 72%; p-LCx: 100%, 72%; m-LCx: 100%, 72%; p-RCA: 94%, 72%; m-RCA: 61%, 50%; d-RCA: 100%, 80%. The 16 slice multi-detector row CT scan provided visualization of the coronary arteries with high resolution. Especially in the group with a mean heart rate of 70 bpm or less, all the coronary segments except the RCA showed diagnostic image quality. Optimal image quality was achieved with a 60-70% trigger delay for all coronary arterial segments, but the best images of RCA were achieved in the earlier cardiac phase in the patients with a mean heart rate of more than 70 bpm

Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

International Nuclear Information System (INIS)

Siewerdsen, Jeffrey H.

2011-01-01

The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions-for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in surgical

Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

Energy Technology Data Exchange (ETDEWEB)

Siewerdsen, Jeffrey H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Traylor Building, Room 718, 720 Rutland Avenue, Baltimore, MD 21205 (United States)

2011-08-21

The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions-for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in surgical

Simultaneous Scanning Electron Microscope Imaging of Topographical and Chemical Contrast Using In-Lens, In-Column, and Everhart-Thornley Detector Systems.

Science.gov (United States)

Zhang, Xinming; Cen, Xi; Ravichandran, Rijuta; Hughes, Lauren A; van Benthem, Klaus

2016-06-01

The scanning electron microscope provides a platform for subnanometer resolution characterization of material morphology with excellent topographic and chemical contrast dependent on the used detectors. For imaging applications, the predominantly utilized signals are secondary electrons (SEs) and backscattered electrons (BSEs) that are emitted from the sample surface. Recent advances in detector technology beyond the traditional Everhart-Thornley geometry have enabled the simultaneous acquisition and discrimination of SE and BSE signals. This study demonstrates the imaging capabilities of a recently introduced new detector system that consists of the combination of two in-lens (I-L) detectors and one in-column (I-C) detector. Coupled with biasing the sample stage to reduce electron-specimen interaction volumes, this trinity of detector geometry allows simultaneous acquisition of signals to distinguish chemical contrast from topographical changes of the sample, including the identification of surface contamination. The I-C detector provides 4× improved topography, whereas the I-L detector closest to the sample offers excellent simultaneous chemical contrast imaging while not limiting the minimization of working distance to obtain optimal lateral resolution. Imaging capabilities and contrast mechanisms for all three detectors are discussed quantitatively in direct comparison to each other and the conventional Everhart-Thornley detector.

Molecular imaging: High-resolution detectors for early diagnosis and therapy monitoring of breast cancer

Energy Technology Data Exchange (ETDEWEB)

Garibaldi, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy)]. E-mail: Franco.garibaldi@iss.infn.it; Cisbani, E. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Colilli, S. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Cusanno, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Fratoni, R. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Giuliani, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Gricia, M. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Lucentini, M. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Fratoni, R. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Lo Meo, S. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Magliozzi, M.L. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Santanvenere, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Cinti, M.N. [University La Sapienza, Rome (Italy); Pani, R. [University La Sapienza, Rome (Italy); Pellegrini, R. [University La Sapienza, Rome (Italy); Simonetti, G. [University Tor Vergata, Rome (Italy); Schillaci, O. [University Tor Vergata, Rome (Italy); Del Vecchio, S. [CNR Napoli, Naples (Italy); Salvatore, M. [CNR Napoli, Naples (Italy); Majewski, S. [Jefferson Lab, Newport News, VA (United States); Lanza, R.C. [Massachusetts Institute of Technology, Cambridge, MA (United States); De Vincentis, G. [University La Sapienza, Rome (Italy); Scopinaro, F. [University La Sapienza, Rome (Italy)

2006-12-20

Dedicated high-resolution detectors are required for detection of small cancerous breast tumours by molecular imaging with radionuclides. Absorptive collimation is normally applied in imaging single photon emitters, but it results in a strong reduction in detection efficiency. Systems based on electronic collimation are complex and expensive. For these reasons simulations and measurements have been performed to design optimised dedicated high-resolution mini gamma camera. Critical parameters are contrast and signal-to-noise ratio (SNR). Intrinsic performance (spatial resolution, pixel identification, and response linearity and uniformity) were first optimised. Pixellated scintillator arrays (NaI(Tl)) of different pixel size were coupled to arrays of PSPMTs with different anode pad dimensions (6x6 mm{sup 2} and 3x3 mm{sup 2}). Detectors having a field of view (FOV) of 100x100 mm{sup 2} and 150x200 mm{sup 2} were designed and built. The electronic system allows read out of all the anode pad signals. The collimation technique was then considered and limits of coded aperture option were studied. Preliminary results are presented.

Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications.

Science.gov (United States)

Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew; Shi, Linxi; Gounis, Matthew J; Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo

2016-05-01

High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54 μm. After resampling to 54 �

A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization

International Nuclear Information System (INIS)

Legoupil, S.

1999-01-01

We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system. This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

The effect of dose reduction on image quality in digital radiography using a flat-panel detector: experimental study in rabbits

International Nuclear Information System (INIS)

Jung, Sung Il; Goo, Jin Mo; Lee, Hyun Ju; Moon, Woo Kyung; Lim, Kun Young; Cho, Gyung Goo; Kim, Ji Hoon; Im, Jung Gi; Choi, Jang Yong; Nam, Sang Hee

2005-01-01

To evaluate the effect of dose reduction on image quality in digital radiography using a flat-panel detector. Digital radiographs of 30 rabbits were obtained at two different dose levels (33.23 μGY for the standard dose group and 20.09 μGY for the reduced dose group). The amorphous selenium-based flat-panel detector system had a panel size of 7 x 8.5 inches, a matrix of 1280 x 1536 (pixels?), and a pixel pitch of 138 μm. Four observers evaluated the soft-copy images on a high-resolution video monitor (2560 x 2048 x 8 bits) in random order. The observers rated the visibility of 13 different anatomic structures on a 5-point scale, viz, the retrocardiac lung, subdiaphragmatic lung, heart border, diaphragmatic border, proximal airway, unobscured lung, liver border, kidney border, bowel gas, flank stripe, ribs, and vertebrae in the mediastinal and abdominal regions. Statistical significance was determined using Wilcoxon's signed rank test. There was no statistically significant difference in the visibility of the anatomic structures on digital radiography between the standard and reduced dose groups. Digital radiography using an amorphous selenium-based flat-panel detector can preserve the image quality, though the dose is reduced to 40% of the standard level

The effect of dose reduction on image quality in digital radiography using a flat-panel detector: experimental study in rabbits

Energy Technology Data Exchange (ETDEWEB)

Jung, Sung Il; Goo, Jin Mo; Lee, Hyun Ju; Moon, Woo Kyung; Lim, Kun Young; Cho, Gyung Goo; Kim, Ji Hoon; Im, Jung Gi [Seoul National College of Medicine, Seoul (Korea, Republic of); Choi, Jang Yong; Nam, Sang Hee [Inje University, Seoul (Korea, Republic of)

2005-07-15

To evaluate the effect of dose reduction on image quality in digital radiography using a flat-panel detector. Digital radiographs of 30 rabbits were obtained at two different dose levels (33.23 {mu}GY for the standard dose group and 20.09 {mu}GY for the reduced dose group). The amorphous selenium-based flat-panel detector system had a panel size of 7 x 8.5 inches, a matrix of 1280 x 1536 (pixels?), and a pixel pitch of 138 {mu}m. Four observers evaluated the soft-copy images on a high-resolution video monitor (2560 x 2048 x 8 bits) in random order. The observers rated the visibility of 13 different anatomic structures on a 5-point scale, viz, the retrocardiac lung, subdiaphragmatic lung, heart border, diaphragmatic border, proximal airway, unobscured lung, liver border, kidney border, bowel gas, flank stripe, ribs, and vertebrae in the mediastinal and abdominal regions. Statistical significance was determined using Wilcoxon's signed rank test. There was no statistically significant difference in the visibility of the anatomic structures on digital radiography between the standard and reduced dose groups. Digital radiography using an amorphous selenium-based flat-panel detector can preserve the image quality, though the dose is reduced to 40% of the standard level.

Observation of meander pattern in signals from superconducting MgB{sub 2} detector by scanning pulsed laser imaging

Energy Technology Data Exchange (ETDEWEB)

Ishida, Takekazu, E-mail: ishida@center.osakafu-u.ac.jp [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Yagi, Ikutaro; Yoshioka, Naohito; Huy, Ho Thanh [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Yotsuya, Tsutomu [Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, 2-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Shimakage, Hisashi [Department of Electrical and Electronic Engineering, College of Engineering, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Miki, Shigehito [Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho, Nishi-ku, Kobe, Hyogo 651-2429 (Japan); Wang, Zhen [Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho, Nishi-ku, Kobe, Hyogo 651-2429 (Japan)

2013-01-15

Highlights: ► We fabricate a superconducting MgB{sub 2} meander detector as a solid-state neutron detector. ► MgB{sub 2} detector uses XYZ stage, optical fiber and focused lens to scan as a microscope. ► The 6 μm line-and-space in meandering pattern can be resolved in signals against pulsed laser. -- Abstract: Superconducting MgB{sub 2} meander detector has been imaged by scanning a spot of 1.5-μm focused pulsed laser. The superconducting detector using high-quality {sup 10}B-enriched MgB{sub 2} thin films at higher operating temperatures has been fabricated to utilize a resistance change induced by the nuclear energy of {sup 10}B and neutron. The MgB{sub 2} detector consists of a 200-nm-thick MgB{sub 2} thin-film meander line, a 300-nm-thick SiO protective layer, and 150-nm-thick Nb electrodes with 1-μm MgB{sub 2} wires. The devices were placed in a 4 K refrigerator to control at a certain temperature below T{sub c}. A scanning laser spot can be used by the combination of the XYZ piezo-drive stage and an optical fibre with an aspheric focused lens. The measurement system is fully controlled by LabVIEW based software. We succeeded in observing a line-and-space image of a meandering pattern by analysing response signals.

SU-F-I-08: CT Image Ring Artifact Reduction Based On Prior Image

Energy Technology Data Exchange (ETDEWEB)

Yuan, C; Qi, H; Chen, Z; Wu, S; Xu, Y; Zhou, L [Southern Medical University, Guangzhou, Guangdong (China)

2016-06-15

Purpose: In computed tomography (CT) system, CT images with ring artifacts will be reconstructed when some adjacent bins of detector don’t work. The ring artifacts severely degrade CT image quality. We present a useful CT ring artifacts reduction based on projection data correction, aiming at estimating the missing data of projection data accurately, thus removing the ring artifacts of CT images. Methods: The method consists of ten steps: 1) Identification of abnormal pixel line in projection sinogram; 2) Linear interpolation within the pixel line of projection sinogram; 3) FBP reconstruction using interpolated projection data; 4) Filtering FBP image using mean filter; 5) Forwarding projection of filtered FBP image; 6) Subtraction forwarded projection from original projection; 7) Linear interpolation of abnormal pixel line area in the subtraction projection; 8) Adding the interpolated subtraction projection on the forwarded projection; 9) FBP reconstruction using corrected projection data; 10) Return to step 4 until the pre-set iteration number is reached. The method is validated on simulated and real data to restore missing projection data and reconstruct ring artifact-free CT images. Results: We have studied impact of amount of dead bins of CT detector on the accuracy of missing data estimation in projection sinogram. For the simulated case with a resolution of 256 by 256 Shepp-Logan phantom, three iterations are sufficient to restore projection data and reconstruct ring artifact-free images when the dead bins rating is under 30%. The dead-bin-induced artifacts are substantially reduced. More iteration number is needed to reconstruct satisfactory images while the rating of dead bins increases. Similar results were found for a real head phantom case. Conclusion: A practical CT image ring artifact correction scheme based on projection data is developed. This method can produce ring artifact-free CT images feasibly and effectively.

SU-F-I-08: CT Image Ring Artifact Reduction Based On Prior Image

International Nuclear Information System (INIS)

Yuan, C; Qi, H; Chen, Z; Wu, S; Xu, Y; Zhou, L

2016-01-01

Purpose: In computed tomography (CT) system, CT images with ring artifacts will be reconstructed when some adjacent bins of detector don’t work. The ring artifacts severely degrade CT image quality. We present a useful CT ring artifacts reduction based on projection data correction, aiming at estimating the missing data of projection data accurately, thus removing the ring artifacts of CT images. Methods: The method consists of ten steps: 1) Identification of abnormal pixel line in projection sinogram; 2) Linear interpolation within the pixel line of projection sinogram; 3) FBP reconstruction using interpolated projection data; 4) Filtering FBP image using mean filter; 5) Forwarding projection of filtered FBP image; 6) Subtraction forwarded projection from original projection; 7) Linear interpolation of abnormal pixel line area in the subtraction projection; 8) Adding the interpolated subtraction projection on the forwarded projection; 9) FBP reconstruction using corrected projection data; 10) Return to step 4 until the pre-set iteration number is reached. The method is validated on simulated and real data to restore missing projection data and reconstruct ring artifact-free CT images. Results: We have studied impact of amount of dead bins of CT detector on the accuracy of missing data estimation in projection sinogram. For the simulated case with a resolution of 256 by 256 Shepp-Logan phantom, three iterations are sufficient to restore projection data and reconstruct ring artifact-free images when the dead bins rating is under 30%. The dead-bin-induced artifacts are substantially reduced. More iteration number is needed to reconstruct satisfactory images while the rating of dead bins increases. Similar results were found for a real head phantom case. Conclusion: A practical CT image ring artifact correction scheme based on projection data is developed. This method can produce ring artifact-free CT images feasibly and effectively.

Comparison of dose and image quality of a Flat-panel detector and an image intensifier; Comparacao da dose e qualidade da imagem de um detector Flatpanel e um intensificador de imagem

Energy Technology Data Exchange (ETDEWEB)

Lazzaro, M.; Friedrich, B.Q.; Luz, R.M. da; Silva, A.M.M. da, E-mail: marcos.lazzaro@acad.pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil)

2016-07-01

With the development of new technologies, have emerged new conversion methods of X-ray image, such as flat panel detectors. The aim of this work is the comparison of entrance surface air kerma (ESAK) and image quality between an image intensifier type of detector (A) and a flat panel (B). The ESAK was obtained by placing a ionization chamber under PMMA simulators of 10, 20 and 30 cm and the image quality was obtained by using the TOR {sup 18}FG simulator. The ESAK to the equipment A is higher when compared to the equipment B. The high contrast resolution is better for the equipment A for all thicknesses of simulators. The equipment A has low contrast resolution with a better viewing threshold for thicknesses of 10 and 20 cm, and a worse performance for 30 cm. It is concluded that the equipment B has ESAK smaller and despite having lower resolution, in almost all cases, have appropriate image quality for diagnosis. (author)

Material specific X-ray imaging using an energy-dispersive pixel detector