Optimizing a three-stage Compton camera for measuring prompt gamma rays emitted during proton radiotherapy

PubMed Central

Peterson, S W; Robertson, D; Polf, J

2011-01-01

In this work, we investigate the use of a three-stage Compton camera to measure secondary prompt gamma rays emitted from patients treated with proton beam radiotherapy. The purpose of this study was (1) to develop an optimal three-stage Compton camera specifically designed to measure prompt gamma rays emitted from tissue and (2) to determine the feasibility of using this optimized Compton camera design to measure and image prompt gamma rays emitted during proton beam irradiation. The three-stage Compton camera was modeled in Geant4 as three high-purity germanium detector stages arranged in parallel-plane geometry. Initially, an isotropic gamma source ranging from 0 to 15 MeV was used to determine lateral width and thickness of the detector stages that provided the optimal detection efficiency. Then, the gamma source was replaced by a proton beam irradiating a tissue phantom to calculate the overall efficiency of the optimized camera for detecting emitted prompt gammas. The overall calculated efficiencies varied from ~10−6 to 10−3 prompt gammas detected per proton incident on the tissue phantom for several variations of the optimal camera design studied. Based on the overall efficiency results, we believe it feasible that a three-stage Compton camera could detect a sufficient number of prompt gammas to allow measurement and imaging of prompt gamma emission during proton radiotherapy. PMID:21048295

Lymphoscintigraphy

MedlinePlus

... The special camera and imaging techniques used in nuclear medicine include the gamma camera and single-photon emission-computed tomography (SPECT). The gamma camera, also called a scintillation camera, detects radioactive energy that is emitted from the patient's body and ...

Hepatobiliary

MedlinePlus

... The special camera and imaging techniques used in nuclear medicine include the gamma camera and single-photon emission-computed tomography (SPECT). The gamma camera, also called a scintillation camera, detects radioactive energy that is emitted from the patient's body and ...

[Results of testing of MINISKAN mobile gamma-ray camera and specific features of its design].

PubMed

Utkin, V M; Kumakhov, M A; Blinov, N N; Korsunskiĭ, V N; Fomin, D K; Kolesnikova, N V; Tultaev, A V; Nazarov, A A; Tararukhina, O B

2007-01-01

The main results of engineering, biomedical, and clinical testing of MINISKAN mobile gamma-ray camera are presented. Specific features of the camera hardware and software, as well as the main technical specifications, are described. The gamma-ray camera implements a new technology based on reconstructive tomography, aperture encoding, and digital processing of signals.

General Nuclear Medicine

MedlinePlus

... The special camera and imaging techniques used in nuclear medicine include the gamma camera and single-photon emission-computed tomography (SPECT). The gamma camera, also called a scintillation camera, detects radioactive energy that is emitted from the patient's body and ...

Neutron and gamma irradiation effects on power semiconductor switches

NASA Technical Reports Server (NTRS)

Schwarze, G. E.; Frasca, A. J.

1990-01-01

The performance characteristics of high-power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

Neutron and gamma irradiation effects on power semiconductor switches

NASA Technical Reports Server (NTRS)

Schwarze, G. E.; Frasca, A. J.

1990-01-01

The performance characteristics of high power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

Study on Effects of Gamma-Ray Irradiation on TlBr Semiconductor Detectors

NASA Astrophysics Data System (ADS)

Matsumura, Motohiro; Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira; Kimura, Norihisa; Nagano, Nobumichi; Hitomi, Keitaro

Radiation hardness of thallium bromide (TlBr) semiconductor detectors to 60Co gamma-ray irradiation was evaluated. The energy spectra and μτ products of electrons were measured to evaluate the irradiation effects. No significant degradation of spectroscopic performance of the TlBr detector for 137Cs gamma-rays was observed up to 45 kGy irradiation. Although the μτ products of electrons in the TlBr detector slightly decreased, position of the photo-peak was stable without significant degradation after the gamma-ray irradiation. We confirmed that the TlBr semiconductor detector has a high tolerance for gamma-ray irradiation at least up to 45 kGy.

Skeletal Scintigraphy (Bone Scan)

MedlinePlus

... The special camera and imaging techniques used in nuclear medicine include the gamma camera and single-photon emission-computed tomography (SPECT). The gamma camera, also called a scintillation camera, detects radioactive energy that is emitted from the patient's body and ...

Cameras for semiconductor process control

NASA Technical Reports Server (NTRS)

Porter, W. A.; Parker, D. L.

1977-01-01

The application of X-ray topography to semiconductor process control is described, considering the novel features of the high speed camera and the difficulties associated with this technique. The most significant results on the effects of material defects on device performance are presented, including results obtained using wafers processed entirely within this institute. Defects were identified using the X-ray camera and correlations made with probe data. Also included are temperature dependent effects of material defects. Recent applications and improvements of X-ray topographs of silicon-on-sapphire and gallium arsenide are presented with a description of a real time TV system prototype and of the most recent vacuum chuck design. Discussion is included of our promotion of the use of the camera by various semiconductor manufacturers.

Commissioning of a new SeHCAT detector and comparison with an uncollimated gamma camera.

PubMed

Taylor, Jonathan C; Hillel, Philip G; Himsworth, John M

2014-10-01

Measurements of SeHCAT (tauroselcholic [75selenium] acid) retention have been used to diagnose bile acid malabsorption for a number of years. In current UK practice the vast majority of centres calculate uptake using an uncollimated gamma camera. Because of ever-increasing demands on gamma camera time, a new 'probe' detector was designed, assembled and commissioned. To validate the system, nine patients were scanned at day 0 and day 7 with both the new probe detector and an uncollimated gamma camera. Commissioning results were largely in line with expectations. Spatial resolution (full-width 95% of maximum) at 1 m was 36.6 cm, the background count rate was 24.7 cps and sensitivity at 1 m was 720.8 cps/MBq. The patient comparison study showed a mean absolute difference in retention measurements of 0.8% between the probe and uncollimated gamma camera, and SD of ± 1.8%. The study demonstrated that it is possible to create a simple, reproducible SeHCAT measurement system using a commercially available scintillation detector. Retention results from the probe closely agreed with those from the uncollimated gamma camera.

X-ray topography as a process control tool in semiconductor and microcircuit manufacture

NASA Technical Reports Server (NTRS)

Parker, D. L.; Porter, W. A.

1977-01-01

A bent wafer camera, designed to identify crystal lattice defects in semiconductor materials, was investigated. The camera makes use of conventional X-ray topographs and an innovative slightly bent wafer which allows rays from the point source to strike all portions of the wafer simultaneously. In addition to being utilized in solving production process control problems, this camera design substantially reduces the cost per topograph.

Development of an all-in-one gamma camera/CCD system for safeguard verification

NASA Astrophysics Data System (ADS)

Kim, Hyun-Il; An, Su Jung; Chung, Yong Hyun; Kwak, Sung-Woo

2014-12-01

For the purpose of monitoring and verifying efforts at safeguarding radioactive materials in various fields, a new all-in-one gamma camera/charged coupled device (CCD) system was developed. This combined system consists of a gamma camera, which gathers energy and position information on gamma-ray sources, and a CCD camera, which identifies the specific location in a monitored area. Therefore, 2-D image information and quantitative information regarding gamma-ray sources can be obtained using fused images. A gamma camera consists of a diverging collimator, a 22 × 22 array CsI(Na) pixelated scintillation crystal with a pixel size of 2 × 2 × 6 mm3 and Hamamatsu H8500 position-sensitive photomultiplier tube (PSPMT). The Basler scA640-70gc CCD camera, which delivers 70 frames per second at video graphics array (VGA) resolution, was employed. Performance testing was performed using a Co-57 point source 30 cm from the detector. The measured spatial resolution and sensitivity were 4.77 mm full width at half maximum (FWHM) and 7.78 cps/MBq, respectively. The energy resolution was 18% at 122 keV. These results demonstrate that the combined system has considerable potential for radiation monitoring.

Solid-state framing camera with multiple time frames

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, K. L.; Stewart, R. E.; Steele, P. T.

2013-10-07

A high speed solid-state framing camera has been developed which can operate over a wide range of photon energies. This camera measures the two-dimensional spatial profile of the flux incident on a cadmium selenide semiconductor at multiple times. This multi-frame camera has been tested at 3.1 eV and 4.5 keV. The framing camera currently records two frames with a temporal separation between the frames of 5 ps but this separation can be varied between hundreds of femtoseconds up to nanoseconds and the number of frames can be increased by angularly multiplexing the probe beam onto the cadmium selenide semiconductor.

Color reproduction software for a digital still camera

NASA Astrophysics Data System (ADS)

Lee, Bong S.; Park, Du-Sik; Nam, Byung D.

1998-04-01

We have developed a color reproduction software for a digital still camera. The image taken by the camera was colorimetrically reproduced on the monitor after characterizing the camera and the monitor, and color matching between two devices. The reproduction was performed at three levels; level processing, gamma correction, and color transformation. The image contrast was increased after the level processing adjusting the level of dark and bright portions of the image. The relationship between the level processed digital values and the measured luminance values of test gray samples was calculated, and the gamma of the camera was obtained. The method for getting the unknown monitor gamma was proposed. As a result, the level processed values were adjusted by the look-up table created by the camera and the monitor gamma correction. For a color transformation matrix for the camera, 3 by 3 or 3 by 4 matrix was used, which was calculated by the regression between the gamma corrected values and the measured tristimulus values of each test color samples the various reproduced images were displayed on the dialogue box implemented in our software, which were generated according to four illuminations for the camera and three color temperatures for the monitor. An user can easily choose he best reproduced image comparing each others.

Performance evaluation for pinhole collimators of small gamma camera by MTF and NNPS analysis: Monte Carlo simulation study

NASA Astrophysics Data System (ADS)

Jeon, Hosang; Kim, Hyunduk; Cha, Bo Kyung; Kim, Jong Yul; Cho, Gyuseong; Chung, Yong Hyun; Yun, Jong-Il

2009-06-01

Presently, the gamma camera system is widely used in various medical diagnostic, industrial and environmental fields. Hence, the quantitative and effective evaluation of its imaging performance is essential for design and quality assurance. The National Electrical Manufacturers Association (NEMA) standards for gamma camera evaluation are insufficient to perform sensitive evaluation. In this study, modulation transfer function (MTF) and normalized noise power spectrum (NNPS) will be suggested to evaluate the performance of small gamma camera with changeable pinhole collimators using Monte Carlo simulation. We simulated the system with a cylinder and a disk source, and seven different pinhole collimators from 1- to 4-mm-diameter pinhole with lead. The MTF and NNPS data were obtained from output images and were compared with full-width at half-maximum (FWHM), sensitivity and differential uniformity. In the result, we found that MTF and NNPS are effective and novel standards to evaluate imaging performance of gamma cameras instead of conventional NEMA standards.

Online gamma-camera imaging of 103Pd seeds (OGIPS) for permanent breast seed implantation

NASA Astrophysics Data System (ADS)

Ravi, Ananth; Caldwell, Curtis B.; Keller, Brian M.; Reznik, Alla; Pignol, Jean-Philippe

2007-09-01

Permanent brachytherapy seed implantation is being investigated as a mode of accelerated partial breast irradiation for early stage breast cancer patients. Currently, the seeds are poorly visualized during the procedure making it difficult to perform a real-time correction of the implantation if required. The objective was to determine if a customized gamma-camera can accurately localize the seeds during implantation. Monte Carlo simulations of a CZT based gamma-camera were used to assess whether images of suitable quality could be derived by detecting the 21 keV photons emitted from 74 MBq 103Pd brachytherapy seeds. A hexagonal parallel hole collimator with a hole length of 38 mm, hole diameter of 1.2 mm and 0.2 mm septa, was modeled. The design of the gamma-camera was evaluated on a realistic model of the breast and three layers of the seed distribution (55 seeds) based on a pre-implantation CT treatment plan. The Monte Carlo simulations showed that the gamma-camera was able to localize the seeds with a maximum error of 2.0 mm, using only two views and 20 s of imaging. A gamma-camera can potentially be used as an intra-procedural image guidance system for quality assurance for permanent breast seed implantation.

Molecular breast imaging using a dedicated high-performance instrument

NASA Astrophysics Data System (ADS)

O'Connor, Michael K.; Wagenaar, Douglas; Hruska, Carrie B.; Phillips, Stephen; Caravaglia, Gina; Rhodes, Deborah

2006-08-01

In women with radiographically dense breasts, the sensitivity of mammography is less than 50%. With the increase in the percent of women with dense breasts, it is important to look at alternative screening techniques for this population. This article reviews the strengths and weaknesses of current imaging techniques and focuses on recent developments in semiconductor-based gamma camera systems that offer significant improvements in image quality over that achievable with single-crystal sodium iodide systems. We have developed a technique known as Molecular Breast Imaging (MBI) using small field of view Cadmium Zinc Telluride (CZT) gamma cameras that permits the breast to be imaged in a similar manner to mammography, using light pain-free compression. Computer simulations and experimental studies have shown that use of low-energy high sensitivity collimation coupled with the excellent energy resolution and intrinsic spatial resolution of CZT detectors provides optimum image quality for the detection of small breast lesions. Preliminary clinical studies with a prototype dual-detector system have demonstrated that Molecular Breast Imaging has a sensitivity of ~90% for the detection of breast tumors less than 10 mm in diameter. By comparison, conventional scintimammography only achieves a sensitivity of 50% in the detection of lesions < 10 mm. Because Molecular Breast Imaging is not affected by breast density, this technique may offer an important adjunct to mammography in the evaluation of women with dense breast parenchyma.

Hard X-ray and low-energy gamma-ray spectrometers

NASA Technical Reports Server (NTRS)

Gehrels, N.; Crannell, C. J.; Orwig, L. E.; Forrest, D. J.; Lin, R. P.; Starr, R.

1988-01-01

Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resoluton for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.

An evolution of technologies and applications of gamma imagers in the nuclear cycle industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalil, R. A.; Carrel, F.; Menaa, N.

The tracking of radiation contamination and distribution has become a high priority in the nuclear cycle industry in order to respect the ALARA principle which is a main challenge during decontamination and dismantling activities. To support this need, AREVA/CANBERRA and CEA LIST have been actively carrying out research and development on a gamma-radiation imager. In this paper we will present the new generation of gamma camera, called GAMPIX. This system is based on the Timepix chip, hybridized with a CdTe substrate. A coded mask could be used in order to increase the sensitivity of the camera. Moreover, due to themore » USB connection with a standard computer, this gamma camera is immediately operational and user-friendly. The final system is a very compact gamma camera (global weight is less than 1 kg without any shielding) which could be used as a hand-held device for radioprotection purposes. In this article, we present the main characteristics of this new generation of gamma camera and we expose experimental results obtained during in situ measurements. Even though we present preliminary results the final product is under industrialization phase to address various applications specifications. (authors)« less

Development of gamma-photon/Cerenkov-light hybrid system for simultaneous imaging of I-131 radionuclide

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Suzuki, Mayumi; Kato, Katsuhiko; Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Ogata, Yoshimune; Hatazawa, Jun

2016-09-01

Although iodine 131 (I-131) is used for radionuclide therapy, high resolution images are difficult to obtain with conventional gamma cameras because of the high energy of I-131 gamma photons (364 keV). Cerenkov-light imaging is a possible method for beta emitting radionuclides, and I-131 (606 MeV maximum beta energy) is a candidate to obtain high resolution images. We developed a high energy gamma camera system for I-131 radionuclide and combined it with a Cerenkov-light imaging system to form a gamma-photon/Cerenkov-light hybrid imaging system to compare the simultaneously measured images of these two modalities. The high energy gamma imaging detector used 0.85-mm×0.85-mm×10-mm thick GAGG scintillator pixels arranged in a 44×44 matrix with a 0.1-mm thick reflector and optical coupled to a Hamamatsu 2 in. square position sensitive photomultiplier tube (PSPMT: H12700 MOD). The gamma imaging detector was encased in a 2 cm thick tungsten shield, and a pinhole collimator was mounted on its top to form a gamma camera system. The Cerenkov-light imaging system was made of a high sensitivity cooled CCD camera. The Cerenkov-light imaging system was combined with the gamma camera using optical mirrors to image the same area of the subject. With this configuration, we simultaneously imaged the gamma photons and the Cerenkov-light from I-131 in the subjects. The spatial resolution and sensitivity of the gamma camera system for I-131 were respectively 3 mm FWHM and 10 cps/MBq for the high sensitivity collimator at 10 cm from the collimator surface. The spatial resolution of the Cerenkov-light imaging system was 0.64 mm FWHM at 10 cm from the system surface. Thyroid phantom and rat images were successfully obtained with the developed gamma-photon/Cerenkov-light hybrid imaging system, allowing direct comparison of these two modalities. Our developed gamma-photon/Cerenkov-light hybrid imaging system will be useful to evaluate the advantages and disadvantages of these two modalities.

Gate simulation of Compton Ar-Xe gamma-camera for radionuclide imaging in nuclear medicine

NASA Astrophysics Data System (ADS)

Dubov, L. Yu; Belyaev, V. N.; Berdnikova, A. K.; Bolozdynia, A. I.; Akmalova, Yu A.; Shtotsky, Yu V.

2017-01-01

Computer simulations of cylindrical Compton Ar-Xe gamma camera are described in the current report. Detection efficiency of cylindrical Ar-Xe Compton camera with internal diameter of 40 cm is estimated as1-3%that is 10-100 times higher than collimated Anger’s camera. It is shown that cylindrical Compton camera can image Tc-99m radiotracer distribution with uniform spatial resolution of 20 mm through the whole field of view.

Microchannel plate streak camera

DOEpatents

Wang, Ching L.

1989-01-01

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 KeV x-rays.

A novel fully integrated handheld gamma camera

NASA Astrophysics Data System (ADS)

Massari, R.; Ucci, A.; Campisi, C.; Scopinaro, F.; Soluri, A.

2016-10-01

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

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

NASA Astrophysics Data System (ADS)

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 (< 100 micron) and many other advantages over traditional gamma cameras. This work focuses on 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 portable and mobile capabilities for easy handling and on-site applications at remote locations where hospital facilities are not available.

Developments in mercuric iodide gamma ray imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patt, B.E.; Beyerle, A.G.; Dolin, R.C.

A mercuric iodide gamma-ray imaging array and camera system previously described has been characterized for spatial and energy resolution. Based on this data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criterion for the new camera will be presented. 2 refs., 7 figs.

Material efficiency studies for a Compton camera designed to measure characteristic prompt gamma rays emitted during proton beam radiotherapy

PubMed Central

Robertson, Daniel; Polf, Jerimy C; Peterson, Steve W; Gillin, Michael T; Beddar, Sam

2011-01-01

Prompt gamma rays emitted from biological tissues during proton irradiation carry dosimetric and spectroscopic information that can assist with treatment verification and provide an indication of the biological response of the irradiated tissues. Compton cameras are capable of determining the origin and energy of gamma rays. However, prompt gamma monitoring during proton therapy requires new Compton camera designs that perform well at the high gamma energies produced when tissues are bombarded with therapeutic protons. In this study we optimize the materials and geometry of a three-stage Compton camera for prompt gamma detection and calculate the theoretical efficiency of such a detector. The materials evaluated in this study include germanium, bismuth germanate (BGO), NaI, xenon, silicon and lanthanum bromide (LaBr3). For each material, the dimensions of each detector stage were optimized to produce the maximum number of relevant interactions. These results were used to predict the efficiency of various multi-material cameras. The theoretical detection efficiencies of the most promising multi-material cameras were then calculated for the photons emitted from a tissue-equivalent phantom irradiated by therapeutic proton beams ranging from 50 to 250 MeV. The optimized detector stages had a lateral extent of 10 × 10 cm2 with the thickness of the initial two stages dependent on the detector material. The thickness of the third stage was fixed at 10 cm regardless of material. The most efficient single-material cameras were composed of germanium (3 cm) and BGO (2.5 cm). These cameras exhibited efficiencies of 1.15 × 10−4 and 9.58 × 10−5 per incident proton, respectively. The most efficient multi-material camera design consisted of two initial stages of germanium (3 cm) and a final stage of BGO, resulting in a theoretical efficiency of 1.26 × 10−4 per incident proton. PMID:21508442

Prompt gamma imaging of proton pencil beams at clinical dose rate

NASA Astrophysics Data System (ADS)

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

2014-10-01

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

Feasibility study of a gamma camera for monitoring nuclear materials in the PRIDE facility

NASA Astrophysics Data System (ADS)

Jo, Woo Jin; Kim, Hyun-Il; An, Su Jung; Lee, Chae Young; Song, Han-Kyeol; Chung, Yong Hyun; Shin, Hee-Sung; Ahn, Seong-Kyu; Park, Se-Hwan

2014-05-01

The Korea Atomic Energy Research Institute (KAERI) has been developing pyroprocessing technology, in which actinides are recovered together with plutonium. There is no pure plutonium stream in the process, so it has an advantage of proliferation resistance. Tracking and monitoring of nuclear materials through the pyroprocess can significantly improve the transparency of the operation and safeguards. An inactive engineering-scale integrated pyroprocess facility, which is the PyRoprocess Integrated inactive DEmonstration (PRIDE) facility, was constructed to demonstrate engineering-scale processes and the integration of each unit process. the PRIDE facility may be a good test bed to investigate the feasibility of a nuclear material monitoring system. In this study, we designed a gamma camera system for nuclear material monitoring in the PRIDE facility by using a Monte Carlo simulation, and we validated the feasibility of this system. Two scenarios, according to locations of the gamma camera, were simulated using GATE (GEANT4 Application for Tomographic Emission) version 6. A prototype gamma camera with a diverging-slat collimator was developed, and the simulated and experimented results agreed well with each other. These results indicate that a gamma camera to monitor the nuclear material in the PRIDE facility can be developed.

A comparison between the use of a shadow shield whole body counter and an uncollimated gamma camera ain the assessment of the seven-day retention of SeHCAT.

PubMed

Hames, T K; Condon, B R; Fleming, J S; Phillips, G; Holdstock, G; Smith, C L; Howlett, P J; Ackery, D

1984-07-01

We have compared the 7-day retention of the radioisotope bile salt analogue SeHCAT (75Se-23-selena-25-homotaurocholate), by whole body counting and by uncollimated gamma camera measurement, in phantoms and in 25 patients with inflammatory bowel disease. The results correlate with a linear correlation coefficient of 0.96. An uncollimated gamma camera can be used to assess bile acid malabsorption when a whole body radioactivity monitor is not available.

Demonstration of in-vivo Multi-Probe Tracker Based on a Si/CdTe Semiconductor Compton Camera

NASA Astrophysics Data System (ADS)

Takeda, Shin'ichiro; Odaka, Hirokazu; Ishikawa, Shin-nosuke; Watanabe, Shin; Aono, Hiroyuki; Takahashi, Tadayuki; Kanayama, Yousuke; Hiromura, Makoto; Enomoto, Shuichi

2012-02-01

By using a prototype Compton camera consisting of silicon (Si) and cadmium telluride (CdTe) semiconductor detectors, originally developed for the ASTRO-H satellite mission, an experiment involving imaging multiple radiopharmaceuticals injected into a living mouse was conducted to study its feasibility for medical imaging. The accumulation of both iodinated (131I) methylnorcholestenol and 85Sr into the mouse's organs was simultaneously imaged by the prototype. This result implies that the Compton camera is expected to become a multi-probe tracker available in nuclear medicine and small animal imaging.

A novel Compton camera design featuring a rear-panel shield for substantial noise reduction in gamma-ray images

NASA Astrophysics Data System (ADS)

Nishiyama, T.; Kataoka, J.; Kishimoto, A.; Fujita, T.; Iwamoto, Y.; Taya, T.; Ohsuka, S.; Nakamura, S.; Hirayanagi, M.; Sakurai, N.; Adachi, S.; Uchiyama, T.

2014-12-01

After the Japanese nuclear disaster in 2011, large amounts of radioactive isotopes were released and still remain a serious problem in Japan. Consequently, various gamma cameras are being developed to help identify radiation hotspots and ensure effective decontamination operation. The Compton camera utilizes the kinematics of Compton scattering to contract images without using a mechanical collimator, and features a wide field of view. For instance, we have developed a novel Compton camera that features a small size (13 × 14 × 15 cm3) and light weight (1.9 kg), but which also achieves high sensitivity thanks to Ce:GAGG scintillators optically coupled wiith MPPC arrays. By definition, in such a Compton camera, gamma rays are expected to scatter in the ``scatterer'' and then be fully absorbed in the ``absorber'' (in what is called a forward-scattered event). However, high energy gamma rays often interact with the detector in the opposite direction - initially scattered in the absorber and then absorbed in the scatterer - in what is called a ``back-scattered'' event. Any contamination of such back-scattered events is known to substantially degrade the quality of gamma-ray images, but determining the order of gamma-ray interaction based solely on energy deposits in the scatterer and absorber is quite difficult. For this reason, we propose a novel yet simple Compton camera design that includes a rear-panel shield (a few mm thick) consisting of W or Pb located just behind the scatterer. Since the energy of scattered gamma rays in back-scattered events is much lower than that in forward-scattered events, we can effectively discriminate and reduce back-scattered events to improve the signal-to-noise ratio in the images. This paper presents our detailed optimization of the rear-panel shield using Geant4 simulation, and describes a demonstration test using our Compton camera.

Experimental setup for camera-based measurements of electrically and optically stimulated luminescence of silicon solar cells and wafers.

PubMed

Hinken, David; Schinke, Carsten; Herlufsen, Sandra; Schmidt, Arne; Bothe, Karsten; Brendel, Rolf

2011-03-01

We report in detail on the luminescence imaging setup developed within the last years in our laboratory. In this setup, the luminescence emission of silicon solar cells or silicon wafers is analyzed quantitatively. Charge carriers are excited electrically (electroluminescence) using a power supply for carrier injection or optically (photoluminescence) using a laser as illumination source. The luminescence emission arising from the radiative recombination of the stimulated charge carriers is measured spatially resolved using a camera. We give details of the various components including cameras, optical filters for electro- and photo-luminescence, the semiconductor laser and the four-quadrant power supply. We compare a silicon charged-coupled device (CCD) camera with a back-illuminated silicon CCD camera comprising an electron multiplier gain and a complementary metal oxide semiconductor indium gallium arsenide camera. For the detection of the luminescence emission of silicon we analyze the dominant noise sources along with the signal-to-noise ratio of all three cameras at different operation conditions.

Slant-hole collimator, dual mode sterotactic localization method

DOEpatents

Weisenberger, Andrew G.

2002-01-01

The use of a slant-hole collimator in the gamma camera of dual mode stereotactic localization apparatus allows the acquisition of a stereo pair of scintimammographic images without repositioning of the gamma camera between image acquisitions.

Comparison of myocardial perfusion imaging between the new high-speed gamma camera and the standard anger camera.

PubMed

Tanaka, Hirokazu; Chikamori, Taishiro; Hida, Satoshi; Uchida, Kenji; Igarashi, Yuko; Yokoyama, Tsuyoshi; Takahashi, Masaki; Shiba, Chie; Yoshimura, Mana; Tokuuye, Koichi; Yamashina, Akira

2013-01-01

Cadmium-zinc-telluride (CZT) solid-state detectors have been recently introduced into the field of myocardial perfusion imaging. The aim of this study was to prospectively compare the diagnostic performance of the CZT high-speed gamma camera (Discovery NM 530c) with that of the standard 3-head gamma camera in the same group of patients. The study group consisted of 150 consecutive patients who underwent a 1-day stress-rest (99m)Tc-sestamibi or tetrofosmin imaging protocol. Image acquisition was performed first on a standard gamma camera with a 15-min scan time each for stress and for rest. All scans were immediately repeated on a CZT camera with a 5-min scan time for stress and a 3-min scan time for rest, using list mode. The correlations between the CZT camera and the standard camera for perfusion and function analyses were strong within narrow Bland-Altman limits of agreement. Using list mode analysis, image quality for stress was rated as good or excellent in 97% of the 3-min scans, and in 100% of the ≥4-min scans. For CZT scans at rest, similarly, image quality was rated as good or excellent in 94% of the 1-min scans, and in 100% of the ≥2-min scans. The novel CZT camera provides excellent image quality, which is equivalent to standard myocardial single-photon emission computed tomography, despite a short scan time of less than half of the standard time.

Investigations of Au-198 as radiotracer in laboratory porous media using gamma camera: a preliminary study

NASA Astrophysics Data System (ADS)

Othman, N.; Kamal, W. H. B. Wan; Yusof, N. H.; Engku Chik, E. M. F.; Yunos, M. A. S.; Adnan, M. A. K.; Shari, M. R.

2018-01-01

Preliminary experiment has been carried out using irradiated Au-198 as radiotracer inside the laboratory porous media. The objectives are to check the compatibility of Au-198 as the radiotracer inside the porous media as well as to provide insights of fluid hydrodynamics inside the media using gamma camera.198Au is gamma emitter isotope with half-life of 2.7 days and energy of 0.41 MeV (99%). The porous media consists of fine sandstone with grain size 850μm, lubricant as the mimic of original oil in plant (OOIP) or trapped oil and a layer of cement on top of the rig as the bed rock. Gamma camera is arranged next to the porous media in order to capture the movement of radiotracer which has been set to 1minute per frame. Initially, the gold wire which has isotope of 197Au was irradiated inside the rotary rack of Reactor Triga PUSPATI (RTP) to produce 198Au. RTP is located in Nuclear Malaysia, Bangi has energy of 750kW and neutron flux of 5 × 102 n/cm2/s. 198Au, which is in liquid form, is injected inside the porous media and monitored and recorded by gamma camera. The gamma camera gives a quantitative determination of local fluid saturations over the area of observation.

A high-speed digital camera system for the observation of rapid H-alpha fluctuations in solar flares

NASA Technical Reports Server (NTRS)

Kiplinger, Alan L.; Dennis, Brian R.; Orwig, Larry E.

1989-01-01

Researchers developed a prototype digital camera system for obtaining H-alpha images of solar flares with 0.1 s time resolution. They intend to operate this system in conjunction with SMM's Hard X Ray Burst Spectrometer, with x ray instruments which will be available on the Gamma Ray Observatory and eventually with the Gamma Ray Imaging Device (GRID), and with the High Resolution Gamma-Ray and Hard X Ray Spectrometer (HIREGS) which are being developed for the Max '91 program. The digital camera has recently proven to be successful as a one camera system operating in the blue wing of H-alpha during the first Max '91 campaign. Construction and procurement of a second and possibly a third camera for simultaneous observations at other wavelengths are underway as are analyses of the campaign data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemaire, H.; Barat, E.; Carrel, F.

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

SU-G-IeP4-12: Performance of In-111 Coincident Gamma-Ray Counting: A Monte Carlo Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pahlka, R; Kappadath, S; Mawlawi, O

2016-06-15

Purpose: The decay of In-111 results in a non-isotropic gamma-ray cascade, which is normally imaged using a gamma camera. Creating images with a gamma camera using coincident gamma-rays from In-111 has not been previously studied. Our objective was to explore the feasibility of imaging this cascade as coincidence events and to determine the optimal timing resolution and source activity using Monte Carlo simulations. Methods: GEANT4 was used to simulate the decay of the In-111 nucleus and to model the gamma camera. Each photon emission was assigned a timestamp, and the time delay and angular separation for the second gamma-ray inmore » the cascade was consistent with the known intermediate state half-life of 85ns. The gamma-rays are transported through a model of a Siemens dual head Symbia “S” gamma camera with a 5/8-inch thick crystal and medium energy collimators. A true coincident event was defined as a single 171keV gamma-ray followed by a single 245keV gamma-ray within a specified time window (or vice versa). Several source activities (ranging from 10uCi to 5mCi) with and without incorporation of background counts were then simulated. Each simulation was analyzed using varying time windows to assess random events. The noise equivalent count rate (NECR) was computed based on the number of true and random counts for each combination of activity and time window. No scatter events were assumed since sources were simulated in air. Results: As expected, increasing the timing window increased the total number of observed coincidences albeit at the expense of true coincidences. A timing window range of 200–500ns maximizes the NECR at clinically-used source activities. The background rate did not significantly alter the maximum NECR. Conclusion: This work suggests coincident measurements of In-111 gamma-ray decay can be performed with commercial gamma cameras at clinically-relevant activities. Work is ongoing to assess useful clinical applications.« less

Gamma ray camera

DOEpatents

Perez-Mendez, V.

1997-01-21

A gamma ray camera is disclosed for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array. 6 figs.

Gamma ray camera

DOEpatents

Perez-Mendez, Victor

1997-01-01

A gamma ray camera for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array.

System to quantify gamma-ray radial energy deposition in semiconductor detectors

DOEpatents

Kammeraad, Judith E.; Blair, Jerome J.

2001-01-01

A system for measuring gamma-ray radial energy deposition is provided for use in conjunction with a semiconductor detector. The detector comprises two electrodes and a detector material, and defines a plurality of zones within the detecting material in parallel with the two electrodes. The detector produces a charge signal E(t) when a gamma-ray interacts with the detector. Digitizing means are provided for converting the charge signal E(t) into a digitized signal. A computational means receives the digitized signal and calculates in which of the plurality of zones the gamma-ray deposited energy when interacting with the detector. The computational means produces an output indicating the amount of energy deposited by the gamma-ray in each of the plurality of zones.

Neutron, gamma ray and post-irradiation thermal annealing effects on power semiconductor switches

NASA Technical Reports Server (NTRS)

Schwarze, G. E.; Frasca, A. J.

1991-01-01

The effects of neutron and gamma rays on the electrical and switching characteristics of power semiconductor switches must be known and understood by the designer of the power conditioning, control, and transmission subsystem of space nuclear power systems. The SP-100 radiation requirements at 25 m from the nuclear source are a neutron fluence of 10(exp 13) n/sq cm and a gamma dose of 0.5 Mrads. Experimental data showing the effects of neutrons and gamma rays on the performance characteristics of power-type NPN Bipolar Junction Transistors (BJTs), Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and Static Induction Transistors (SITs) are presented. These three types of devices were tested at radiation levels which met or exceeded the SP-100 requirements. For the SP-100 radiation requirements, the BJTs were found to be most sensitive to neutrons, the MOSFETs were most sensitive to gamma rays, and the SITs were only slightly sensitive to neutrons. Post-irradiation thermal anneals at 300 K and up to 425 K were done on these devices and the effectiveness of these anneals are also discussed.

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

PubMed

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

2015-06-01

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

Feasibility of a high-speed gamma-camera design using the high-yield-pileup-event-recovery method.

PubMed

Wong, W H; Li, H; Uribe, J; Baghaei, H; Wang, Y; Yokoyama, S

2001-04-01

Higher count-rate gamma cameras than are currently used are needed if the technology is to fulfill its promise in positron coincidence imaging, radionuclide therapy dosimetry imaging, and cardiac first-pass imaging. The present single-crystal design coupled with conventional detector electronics and the traditional Anger-positioning algorithm hinder higher count-rate imaging because of the pileup of gamma-ray signals in the detector and electronics. At an interaction rate of 2 million events per second, the fraction of nonpileup events is < 20% of the total incident events. Hence, the recovery of pileup events can significantly increase the count-rate capability, increase the yield of imaging photons, and minimize image artifacts associated with pileups. A new technology to significantly enhance the performance of gamma cameras in this area is introduced. We introduce a new electronic design called high-yield-pileup-event-recovery (HYPER) electronics for processing the detector signal in gamma cameras so that the individual gamma energies and positions of pileup events, including multiple pileups, can be resolved and recovered despite the mixing of signals. To illustrate the feasibility of the design concept, we have developed a small gamma-camera prototype with the HYPER-Anger electronics. The camera has a 10 x 10 x 1 cm NaI(Tl) crystal with four photomultipliers. Hot-spot and line sources with very high 99mTc activities were imaged. The phantoms were imaged continuously from 60,000 to 3,500,000 counts per second to illustrate the efficacy of the method as a function of counting rates. At 2-3 million events per second, all phantoms were imaged with little distortion, pileup, and dead-time loss. At these counting rates, multiple pileup events (> or = 3 events piling together) were the predominate occurrences, and the HYPER circuit functioned well to resolve and recover these events. The full width at half maximum of the line-spread function at 3,000,000 counts per second was 1.6 times that at 60,000 counts per second. This feasibility study showed that the HYPER electronic concept works; it can significantly increase the count-rate capability and dose efficiency of gamma cameras. In a larger clinical camera, multiple HYPER-Anger circuits may be implemented to further improve the imaging counting rates that we have shown by multiple times. This technology would facilitate the use of gamma cameras for radionuclide therapy dosimetry imaging, cardiac first-pass imaging, and positron coincidence imaging and the simultaneous acquisition of transmission and emission data using different isotopes with less cross-contamination between transmission and emission data.

Camera Concepts for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Nepomuk Otte, Adam

2009-05-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. Design goals are ten times better sensitivity, higher angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Each telescope is equipped with a camera that detects and records the Cherenkov-light flashes from air showers. The camera is comprised of a pixelated focal plane of blue sensitive and fast (nanosecond) photon detectors that detect the photon signal and convert it into an electrical one. The incorporation of trigger electronics and signal digitization into the camera are under study. Given the size of AGIS, the camera must be reliable, robust, and cost effective. We are investigating several directions that include innovative technologies such as Geiger-mode avalanche-photodiodes as a possible detector and switched capacitor arrays for the digitization.

Quality controls for gamma cameras and PET cameras: development of a free open-source ImageJ program

NASA Astrophysics Data System (ADS)

Carlier, Thomas; Ferrer, Ludovic; Berruchon, Jean B.; Cuissard, Regis; Martineau, Adeline; Loonis, Pierre; Couturier, Olivier

2005-04-01

Acquisition data and treatments for quality controls of gamma cameras and Positron Emission Tomography (PET) cameras are commonly performed with dedicated program packages, which are running only on manufactured computers and differ from each other, depending on camera company and program versions. The aim of this work was to develop a free open-source program (written in JAVA language) to analyze data for quality control of gamma cameras and PET cameras. The program is based on the free application software ImageJ and can be easily loaded on any computer operating system (OS) and thus on any type of computer in every nuclear medicine department. Based on standard parameters of quality control, this program includes 1) for gamma camera: a rotation center control (extracted from the American Association of Physics in Medicine, AAPM, norms) and two uniformity controls (extracted from the Institute of Physics and Engineering in Medicine, IPEM, and National Electronic Manufacturers Association, NEMA, norms). 2) For PET systems, three quality controls recently defined by the French Medical Physicist Society (SFPM), i.e. spatial resolution and uniformity in a reconstructed slice and scatter fraction, are included. The determination of spatial resolution (thanks to the Point Spread Function, PSF, acquisition) allows to compute the Modulation Transfer Function (MTF) in both modalities of cameras. All the control functions are included in a tool box which is a free ImageJ plugin and could be soon downloaded from Internet. Besides, this program offers the possibility to save on HTML format the uniformity quality control results and a warning can be set to automatically inform users in case of abnormal results. The architecture of the program allows users to easily add any other specific quality control program. Finally, this toolkit is an easy and robust tool to perform quality control on gamma cameras and PET cameras based on standard computation parameters, is free, run on any type of computer and will soon be downloadable from the net (http://rsb.info.nih.gov/ij/plugins or http://nucleartoolkit.free.fr).

Design and performance tests of the calorimetric tract of a Compton Camera for small-animals imaging

NASA Astrophysics Data System (ADS)

Rossi, P.; Baldazzi, G.; Battistella, A.; Bello, M.; Bollini, D.; Bonvicini, V.; Fontana, C. L.; Gennaro, G.; Moschini, G.; Navarria, F.; Rashevsky, A.; Uzunov, N.; Zampa, G.; Zampa, N.; Vacchi, A.

2011-02-01

The bio-distribution and targeting capability of pharmaceuticals may be assessed in small animals by imaging gamma-rays emitted from radio-isotope markers. Detectors that exploit the Compton concept allow higher gamma-ray efficiency compared to conventional Anger cameras employing collimators, and feature sub-millimeter spatial resolution and compact geometry. We are developing a Compton Camera that has to address several requirements: the high rates typical of the Compton concept; detection of gamma-rays of different energies that may range from 140 keV ( 99 mTc) to 511 keV ( β+ emitters); presence of gamma and beta radiation with energies up to 2 MeV in case of 188Re. The camera consists of a thin position-sensitive Tracker that scatters the gamma ray, and a second position-sensitive detection system to totally absorb the energy of the scattered photons (Calorimeter). In this paper we present the design and discuss the realization of the calorimetric tract, including the choice of scintillator crystal, pixel size, and detector geometry. Simulations of the gamma-ray trajectories from source to detectors have helped to assess the accuracy of the system and decide on camera design. Crystals of different materials, such as LaBr 3 GSO and YAP, and of different size, in continuous or segmented geometry, have been optically coupled to a multi-anode Hamamatsu H8500 detector, allowing measurements of spatial resolution and efficiency.

Optimization and verification of image reconstruction for a Compton camera towards application as an on-line monitor for particle therapy

NASA Astrophysics Data System (ADS)

Taya, T.; Kataoka, J.; Kishimoto, A.; Tagawa, L.; Mochizuki, S.; Toshito, T.; Kimura, M.; Nagao, Y.; Kurita, K.; Yamaguchi, M.; Kawachi, N.

2017-07-01

Particle therapy is an advanced cancer therapy that uses a feature known as the Bragg peak, in which particle beams suddenly lose their energy near the end of their range. The Bragg peak enables particle beams to damage tumors effectively. To achieve precise therapy, the demand for accurate and quantitative imaging of the beam irradiation region or dosage during therapy has increased. The most common method of particle range verification is imaging of annihilation gamma rays by positron emission tomography. Not only 511-keV gamma rays but also prompt gamma rays are generated during therapy; therefore, the Compton camera is expected to be used as an on-line monitor for particle therapy, as it can image these gamma rays in real time. Proton therapy, one of the most common particle therapies, uses a proton beam of approximately 200 MeV, which has a range of ~ 25 cm in water. As gamma rays are emitted along the path of the proton beam, quantitative evaluation of the reconstructed images of diffuse sources becomes crucial, but it is far from being fully developed for Compton camera imaging at present. In this study, we first quantitatively evaluated reconstructed Compton camera images of uniformly distributed diffuse sources, and then confirmed that our Compton camera obtained 3 %(1 σ) and 5 %(1 σ) uniformity for line and plane sources, respectively. Based on this quantitative study, we demonstrated on-line gamma imaging during proton irradiation. Through these studies, we show that the Compton camera is suitable for future use as an on-line monitor for particle therapy.

COMPUTER ANALYSIS OF PLANAR GAMMA CAMERA IMAGES

EPA Science Inventory

COMPUTER ANALYSIS OF PLANAR GAMMA CAMERA IMAGES

T Martonen1 and J Schroeter2

1Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. EPA, Research Triangle Park, NC 27711 USA and 2Curriculum in Toxicology, Unive...

21 CFR 892.1100 - Scintillation (gamma) camera.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Scintillation (gamma) camera. 892.1100 Section 892.1100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... analysis and display equipment, patient and equipment supports, radionuclide anatomical markers, component...

21 CFR 892.1100 - Scintillation (gamma) camera.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scintillation (gamma) camera. 892.1100 Section 892.1100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... analysis and display equipment, patient and equipment supports, radionuclide anatomical markers, component...

21 CFR 892.1100 - Scintillation (gamma) camera.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Scintillation (gamma) camera. 892.1100 Section 892.1100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... analysis and display equipment, patient and equipment supports, radionuclide anatomical markers, component...

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

NASA Astrophysics Data System (ADS)

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

2015-07-01

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

The Multidimensional Integrated Intelligent Imaging project (MI-3)

NASA Astrophysics Data System (ADS)

Allinson, N.; Anaxagoras, T.; Aveyard, J.; Arvanitis, C.; Bates, R.; Blue, A.; Bohndiek, S.; Cabello, J.; Chen, L.; Chen, S.; Clark, A.; Clayton, C.; Cook, E.; Cossins, A.; Crooks, J.; El-Gomati, M.; Evans, P. M.; Faruqi, W.; French, M.; Gow, J.; Greenshaw, T.; Greig, T.; Guerrini, N.; Harris, E. J.; Henderson, R.; Holland, A.; Jeyasundra, G.; Karadaglic, D.; Konstantinidis, A.; Liang, H. X.; Maini, K. M. S.; McMullen, G.; Olivo, A.; O'Shea, V.; Osmond, J.; Ott, R. J.; Prydderch, M.; Qiang, L.; Riley, G.; Royle, G.; Segneri, G.; Speller, R.; Symonds-Tayler, J. R. N.; Triger, S.; Turchetta, R.; Venanzi, C.; Wells, K.; Zha, X.; Zin, H.

2009-06-01

MI-3 is a consortium of 11 universities and research laboratories whose mission is to develop complementary metal-oxide semiconductor (CMOS) active pixel sensors (APS) and to apply these sensors to a range of imaging challenges. A range of sensors has been developed: On-Pixel Intelligent CMOS (OPIC)—designed for in-pixel intelligence; FPN—designed to develop novel techniques for reducing fixed pattern noise; HDR—designed to develop novel techniques for increasing dynamic range; Vanilla/PEAPS—with digital and analogue modes and regions of interest, which has also been back-thinned; Large Area Sensor (LAS)—a novel, stitched LAS; and eLeNA—which develops a range of low noise pixels. Applications being developed include autoradiography, a gamma camera system, radiotherapy verification, tissue diffraction imaging, X-ray phase-contrast imaging, DNA sequencing and electron microscopy.

A small field of view camera for hybrid gamma and optical imaging

NASA Astrophysics Data System (ADS)

Lees, J. E.; Bugby, S. L.; Bhatia, B. S.; Jambi, L. K.; Alqahtani, M. S.; McKnight, W. R.; Ng, A. H.; Perkins, A. C.

2014-12-01

The development of compact low profile gamma-ray detectors has allowed the production of small field of view, hand held imaging devices for use at the patient bedside and in operating theatres. The combination of an optical and a gamma camera, in a co-aligned configuration, offers high spatial resolution multi-modal imaging giving a superimposed scintigraphic and optical image. This innovative introduction of hybrid imaging offers new possibilities for assisting surgeons in localising the site of uptake in procedures such as sentinel node detection. Recent improvements to the camera system along with results of phantom and clinical imaging are reported.

Feasibility of SPECT myocardial perfusion imaging in the super-obese using a multi-head semiconductor camera with attenuation correction.

PubMed

DeCicco, Anthony E; Sokil, Alexis B; Marhefka, Gregary D; Reist, Kirk; Hansen, Christopher L

2015-04-01

Obesity is not only associated with an increased risk of coronary artery disease, but also decreases the accuracy of many diagnostic modalities pertinent to this disease. Advances in myocardial perfusion imaging (MPI) have mitigated somewhat the effects of obesity, although the feasibility of MPI in the super-obese (defined as a BMI > 50) is currently untested. We undertook this study to assess the practicality of MPI in the super-obese using a multi-headed solid-state gamma camera with attenuation correction. We retrospectively identified consecutive super-obese patients referred for MPI at our institution. The images were interpreted by 3 blinded, experienced readers and graded for quality and diagnosis, and subjectively evaluated the contribution of attenuation correction. Clinical follow-up was obtained from review of medical records. 72 consecutive super-obese patients were included. Their BMI ranged from 50 to 67 (55.7 ± 5.1). Stress image quality was considered good or excellent in 45 (63%), satisfactory in 24 (33%), poor in 3 (4%), and uninterpretable in 0 patients. Rest images were considered good or excellent in 34 (49%), satisfactory in 23 (33%), poor in 13 (19%), and uninterpretable in 0 patients. Attenuation correction changed the interpretation in 34 (47%) of studies. MPI is feasible and provides acceptable image quality for super-obese patients, although it may be camera and protocol dependent.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowe, M; Spiro, A; Vogel, R

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

Novel methods for estimating 3D distributions of radioactive isotopes in materials

NASA Astrophysics Data System (ADS)

Iwamoto, Y.; Kataoka, J.; Kishimoto, A.; Nishiyama, T.; Taya, T.; Okochi, H.; Ogata, H.; Yamamoto, S.

2016-09-01

In recent years, various gamma-ray visualization techniques, or gamma cameras, have been proposed. These techniques are extremely effective for identifying "hot spots" or regions where radioactive isotopes are accumulated. Examples of such would be nuclear-disaster-affected areas such as Fukushima or the vicinity of nuclear reactors. However, the images acquired with a gamma camera do not include distance information between radioactive isotopes and the camera, and hence are "degenerated" in the direction of the isotopes. Moreover, depth information in the images is lost when the isotopes are embedded in materials, such as water, sand, and concrete. Here, we propose two methods of obtaining depth information of radioactive isotopes embedded in materials by comparing (1) their spectra and (2) images of incident gamma rays scattered by the materials and direct gamma rays. In the first method, the spectra of radioactive isotopes and the ratios of scattered to direct gamma rays are obtained. We verify experimentally that the ratio increases with increasing depth, as predicted by simulations. Although the method using energy spectra has been studied for a long time, an advantage of our method is the use of low-energy (50-150 keV) photons as scattered gamma rays. In the second method, the spatial extent of images obtained for direct and scattered gamma rays is compared. By performing detailed Monte Carlo simulations using Geant4, we verify that the spatial extent of the position where gamma rays are scattered increases with increasing depth. To demonstrate this, we are developing various gamma cameras to compare low-energy (scattered) gamma-ray images with fully photo-absorbed gamma-ray images. We also demonstrate that the 3D reconstruction of isotopes/hotspots is possible with our proposed methods. These methods have potential applications in the medical fields, and in severe environments such as the nuclear-disaster-affected areas in Fukushima.

A versatile calibration procedure for portable coded aperture gamma cameras and RGB-D sensors

NASA Astrophysics Data System (ADS)

Paradiso, V.; Crivellaro, A.; Amgarou, K.; de Lanaute, N. Blanc; Fua, P.; Liénard, E.

2018-04-01

The present paper proposes a versatile procedure for the geometrical calibration of coded aperture gamma cameras and RGB-D depth sensors, using only one radioactive point source and a simple experimental set-up. Calibration data is then used for accurately aligning radiation images retrieved by means of the γ-camera with the respective depth images computed with the RGB-D sensor. The system resulting from such a combination is thus able to retrieve, automatically, the distance of radioactive hotspots by means of pixel-wise mapping between gamma and depth images. This procedure is of great interest for a wide number of applications, ranging from precise automatic estimation of the shape and distance of radioactive objects to Augmented Reality systems. Incidentally, the corresponding results validated the choice of a perspective design model for a coded aperture γ-camera.

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

PubMed Central

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

2017-01-01

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

Performance of the prototype LaBr3 spectrometer developed for the JET gamma-ray camera upgrade.

PubMed

Rigamonti, D; Muraro, A; Nocente, M; Perseo, V; Boltruczyk, G; Fernandes, A; Figueiredo, J; Giacomelli, L; Gorini, G; Gosk, M; Kiptily, V; Korolczuk, S; Mianowski, S; Murari, A; Pereira, R C; Cippo, E P; Zychor, I; Tardocchi, M

2016-11-01

In this work, we describe the solution developed by the gamma ray camera upgrade enhancement project to improve the spectroscopic properties of the existing JET γ-ray camera. Aim of the project is to enable gamma-ray spectroscopy in JET deuterium-tritium plasmas. A dedicated pilot spectrometer based on a LaBr 3 crystal coupled to a silicon photo-multiplier has been developed. A proper pole zero cancellation network able to shorten the output signal to a length of 120 ns has been implemented allowing for spectroscopy at MHz count rates. The system has been characterized in the laboratory and shows an energy resolution of 5.5% at E γ = 0.662 MeV, which extrapolates favorably in the energy range of interest for gamma-ray emission from fast ions in fusion plasmas.

Development of an omnidirectional gamma-ray imaging Compton camera for low-radiation-level environmental monitoring

NASA Astrophysics Data System (ADS)

Watanabe, Takara; Enomoto, Ryoji; Muraishi, Hiroshi; Katagiri, Hideaki; Kagaya, Mika; Fukushi, Masahiro; Kano, Daisuke; Satoh, Wataru; Takeda, Tohoru; Tanaka, Manobu M.; Tanaka, Souichi; Uchida, Tomohisa; Wada, Kiyoto; Wakamatsu, Ryo

2018-02-01

We have developed an omnidirectional gamma-ray imaging Compton camera for environmental monitoring at low levels of radiation. The camera consisted of only six CsI(Tl) scintillator cubes of 3.5 cm, each of which was readout by super-bialkali photo-multiplier tubes (PMTs). Our camera enables the visualization of the position of gamma-ray sources in all directions (∼4π sr) over a wide energy range between 300 and 1400 keV. The angular resolution (σ) was found to be ∼11°, which was realized using an image-sharpening technique. A high detection efficiency of 18 cps/(µSv/h) for 511 keV (1.6 cps/MBq at 1 m) was achieved, indicating the capability of this camera to visualize hotspots in areas with low-radiation-level contamination from the order of µSv/h to natural background levels. Our proposed technique can be easily used as a low-radiation-level imaging monitor in radiation control areas, such as medical and accelerator facilities.

Mini gamma camera, camera system and method of use

DOEpatents

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

2001-01-01

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

An airborne multispectral imaging system based on two consumer-grade cameras for agricultural remote sensing

USDA-ARS?s Scientific Manuscript database

This paper describes the design and evaluation of an airborne multispectral imaging system based on two identical consumer-grade cameras for agricultural remote sensing. The cameras are equipped with a full-frame complementary metal oxide semiconductor (CMOS) sensor with 5616 × 3744 pixels. One came...

Gamma-ray imaging system for real-time measurements in nuclear waste characterisation

NASA Astrophysics Data System (ADS)

Caballero, L.; Albiol Colomer, F.; Corbi Bellot, A.; Domingo-Pardo, C.; Leganés Nieto, J. L.; Agramunt Ros, J.; Contreras, P.; Monserrate, M.; Olleros Rodríguez, P.; Pérez Magán, D. L.

2018-03-01

A compact, portable and large field-of-view gamma camera that is able to identify, locate and quantify gamma-ray emitting radioisotopes in real-time has been developed. The device delivers spectroscopic and imaging capabilities that enable its use it in a variety of nuclear waste characterisation scenarios, such as radioactivity monitoring in nuclear power plants and more specifically for the decommissioning of nuclear facilities. The technical development of this apparatus and some examples of its application in field measurements are reported in this article. The performance of the presented gamma-camera is also benchmarked against other conventional techniques.

Photodetectors for the Advanced Gamma-ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, Robert G.; Advanced Gamma-ray Imaging System AGIS Collaboration

2010-03-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation very high energy gamma-ray observatory. Design goals include an order of magnitude better sensitivity, better angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Each telescope is equipped with a camera that detects and records the Cherenkov-light flashes from air showers. The camera is comprised of a pixelated focal plane of blue sensitive and fast (nanosecond) photon detectors that detect the photon signal and convert it into an electrical one. Given the scale of AGIS, the camera must be reliable and cost effective. The Schwarzschild-Couder optical design yields a smaller plate scale than present-day Cherenkov telescopes, enabling the use of more compact, multi-pixel devices, including multianode photomultipliers or Geiger avalanche photodiodes. We present the conceptual design of the focal plane for the camera and results from testing candidate! focal plane sensors.

Novel Drift Structures for Silicon and Compound Semiconductor X-Ray and Gamma-Ray Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley E. Patt; Jan S. Iwanczyk

Recently developed silicon- and compound-semiconductor-based drift detector structures have produced excellent performance for charged particles, X rays, and gamma rays and for low-signal visible light detection. The silicon drift detector (SDD) structures that we discuss relate to direct X-ray detectors and scintillation photon detectors coupled with scintillators for gamma rays. Recent designs include several novel features that ensure very low dark current (both bulk silicon dark current and surface dark current) and hence low noise. In addition, application of thin window technology ensures a very high quantum efficiency entrance window on the drift photodetector.

Slit-Slat Collimator Equipped Gamma Camera for Whole-Mouse SPECT-CT Imaging

NASA Astrophysics Data System (ADS)

Cao, Liji; Peter, Jörg

2012-06-01

A slit-slat collimator is developed for a gamma camera intended for small-animal imaging (mice). The tungsten housing of a roof-shaped collimator forms a slit opening, and the slats are made of lead foils separated by sparse polyurethane material. Alignment of the collimator with the camera's pixelated crystal is performed by adjusting a micrometer screw while monitoring a Co-57 point source for maximum signal intensity. For SPECT, the collimator forms a cylindrical field-of-view enabling whole mouse imaging with transaxial magnification and constant on-axis sensitivity over the entire axial direction. As the gamma camera is part of a multimodal imaging system incorporating also x-ray CT, five parameters corresponding to the geometric displacements of the collimator as well as to the mechanical co-alignment between the gamma camera and the CT subsystem are estimated by means of bimodal calibration sources. To illustrate the performance of the slit-slat collimator and to compare its performance to a single pinhole collimator, a Derenzo phantom study is performed. Transaxial resolution along the entire long axis is comparable to a pinhole collimator of same pinhole diameter. Axial resolution of the slit-slat collimator is comparable to that of a parallel beam collimator. Additionally, data from an in-vivo mouse study are presented.

Performance of the prototype LaBr{sub 3} spectrometer developed for the JET gamma-ray camera upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rigamonti, D., E-mail: davide.rigamonti@mib.infn.it; Nocente, M.; Gorini, G.

2016-11-15

In this work, we describe the solution developed by the gamma ray camera upgrade enhancement project to improve the spectroscopic properties of the existing JET γ-ray camera. Aim of the project is to enable gamma-ray spectroscopy in JET deuterium-tritium plasmas. A dedicated pilot spectrometer based on a LaBr{sub 3} crystal coupled to a silicon photo-multiplier has been developed. A proper pole zero cancellation network able to shorten the output signal to a length of 120 ns has been implemented allowing for spectroscopy at MHz count rates. The system has been characterized in the laboratory and shows an energy resolution ofmore » 5.5% at E{sub γ} = 0.662 MeV, which extrapolates favorably in the energy range of interest for gamma-ray emission from fast ions in fusion plasmas.« less

Semiconductor quantum dot scintillation under gamma-ray irradiation.

PubMed

Létant, S E; Wang, T-F

2006-12-01

We recently demonstrated the ability of semiconductor quantum dots to convert alpha radiation into visible photons. In this letter, we report on the scintillation of quantum dots under gamma irradiation and compare the energy resolution of the 59 keV line of americium-241 obtained with our quantum dot-glass nanocomposite to that of a standard sodium iodide scintillator. A factor 2 improvement is demonstrated experimentally and interpreted theoretically using a combination of energy-loss and photon-transport models.

Radiation evaluation study of LSI RAM technologies

NASA Astrophysics Data System (ADS)

Dinger, G. L.; Knoll, M. G.

1980-01-01

Five commercial LSI static random access memory technologies having a 1 kilobit capacity were radiation characterized. Arrays from the transistor-transistor-logic (TTL), Schottky TTL, n-channel metal oxide semiconductor, complementary metal oxide semiconductor (CMOS), and CMOS/silicon on sapphire families were evaluated. Radiation failure thresholds for gamma doserate logic upset, total gamma dose survivability, and neutron fluence survivability were determined. A brief analysis of the radiation failure mechanism for each of the logic families tested is included.

Novel Chalcogenide Materials for x ray and Gamma ray Detection

DTIC Science & Technology

2016-05-01

REPORT OF PROJECT: Novel chalcogenide materials for x - ray and - ray detection HDTRA1-09-1-0044 Mercouri Kanatzidis , PI Northwestern University...investigated semiconductor for hard radiation detection. The μτ products for electrons however are lower than those of CZT, the leading material for X - ray ...Formation of native defects in the gamma- ray detector material, Cs2Hg6S7 Semiconductor devices detecting hard radiation such as x - rays and

Image Sensors Enhance Camera Technologies

NASA Technical Reports Server (NTRS)

2010-01-01

In the 1990s, a Jet Propulsion Laboratory team led by Eric Fossum researched ways of improving complementary metal-oxide semiconductor (CMOS) image sensors in order to miniaturize cameras on spacecraft while maintaining scientific image quality. Fossum s team founded a company to commercialize the resulting CMOS active pixel sensor. Now called the Aptina Imaging Corporation, based in San Jose, California, the company has shipped over 1 billion sensors for use in applications such as digital cameras, camera phones, Web cameras, and automotive cameras. Today, one of every three cell phone cameras on the planet feature Aptina s sensor technology.

Process simulation in digital camera system

NASA Astrophysics Data System (ADS)

Toadere, Florin

2012-06-01

The goal of this paper is to simulate the functionality of a digital camera system. The simulations cover the conversion from light to numerical signal and the color processing and rendering. We consider the image acquisition system to be linear shift invariant and axial. The light propagation is orthogonal to the system. We use a spectral image processing algorithm in order to simulate the radiometric properties of a digital camera. In the algorithm we take into consideration the transmittances of the: light source, lenses, filters and the quantum efficiency of a CMOS (complementary metal oxide semiconductor) sensor. The optical part is characterized by a multiple convolution between the different points spread functions of the optical components. We use a Cooke triplet, the aperture, the light fall off and the optical part of the CMOS sensor. The electrical part consists of the: Bayer sampling, interpolation, signal to noise ratio, dynamic range, analog to digital conversion and JPG compression. We reconstruct the noisy blurred image by blending different light exposed images in order to reduce the photon shot noise, also we filter the fixed pattern noise and we sharpen the image. Then we have the color processing blocks: white balancing, color correction, gamma correction, and conversion from XYZ color space to RGB color space. For the reproduction of color we use an OLED (organic light emitting diode) monitor. The analysis can be useful to assist students and engineers in image quality evaluation and imaging system design. Many other configurations of blocks can be used in our analysis.

Neutron, gamma ray and post-irradiation thermal annealing effects on power semiconductor switches

NASA Technical Reports Server (NTRS)

Schwarze, G. E.; Frasca, A. J.

1991-01-01

Experimental data showing the effects of neutrons and gamma rays on the performance characteristics of power-type NPN bipolar junction transistors (BJTs), metal-oxide-semiconductor field effect transistors (MOSFETs), and static induction transistors (SITs) are given. These three types of devices were tested at radiation levels which met or exceeded the SP-100 requirements. For the SP-100 radiation requirements, the BJTs were found to be most sensitive to neutrons, the MOSFETs were most sensitive to gamma rays, and the SITs were only slightly sensitive to neutrons. Postirradiation thermal anneals at 300 K and up to 425 K were done on these devices and the effectiveness of these anneals are also discussed.

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

PubMed

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

2011-01-01

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

Development and calibration of a new gamma camera detector using large square Photomultiplier Tubes

NASA Astrophysics Data System (ADS)

Zeraatkar, N.; Sajedi, S.; Teimourian Fard, B.; Kaviani, S.; Akbarzadeh, A.; Farahani, M. H.; Sarkar, S.; Ay, M. R.

2017-09-01

Large area scintillation detectors applied in gamma cameras as well as Single Photon Computed Tomography (SPECT) systems, have a major role in in-vivo functional imaging. Most of the gamma detectors utilize hexagonal arrangement of Photomultiplier Tubes (PMTs). In this work we applied large square-shaped PMTs with row/column arrangement and positioning. The Use of large square PMTs reduces dead zones in the detector surface. However, the conventional center of gravity method for positioning may not introduce an acceptable result. Hence, the digital correlated signal enhancement (CSE) algorithm was optimized to obtain better linearity and spatial resolution in the developed detector. The performance of the developed detector was evaluated based on NEMA-NU1-2007 standard. The acquired images using this method showed acceptable uniformity and linearity comparing to three commercial gamma cameras. Also the intrinsic and extrinsic spatial resolutions with low-energy high-resolution (LEHR) collimator at 10 cm from surface of the detector were 3.7 mm and 7.5 mm, respectively. The energy resolution of the camera was measured 9.5%. The performance evaluation demonstrated that the developed detector maintains image quality with a reduced number of used PMTs relative to the detection area.

High-resolution ionization detector and array of such detectors

DOEpatents

McGregor, Douglas S [Ypsilanti, MI; Rojeski, Ronald A [Pleasanton, CA

2001-01-16

A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

Application of gamma imaging techniques for the characterisation of position sensitive gamma detectors

NASA Astrophysics Data System (ADS)

Habermann, T.; Didierjean, F.; Duchêne, G.; Filliger, M.; Gerl, J.; Kojouharov, I.; Li, G.; Pietralla, N.; Schaffner, H.; Sigward, M.-H.

2017-11-01

A device to characterize position-sensitive germanium detectors has been implemented at GSI. The main component of this so called scanning table is a gamma camera that is capable of producing online 2D images of the scanned detector by means of a PET technique. To calibrate the gamma camera Compton imaging is employed. The 2D data can be processed further offline to obtain depth information. Of main interest is the response of the scanned detector in terms of the digitized pulse shapes from the preamplifier. This is an important input for pulse-shape analysis algorithms as they are in use for gamma tracking arrays in gamma spectroscopy. To validate the scanning table, a comparison of its results with a second scanning table implemented at the IPHC Strasbourg is envisaged. For this purpose a pixelated germanium detector has been scanned.

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

PubMed

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

2013-01-01

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

Review: comparison of PET rubidium-82 with conventional SPECT myocardial perfusion imaging

PubMed Central

Ghotbi, Adam A; Kjær, Andreas; Hasbak, Philip

2014-01-01

Nuclear cardiology has for many years been focused on gamma camera technology. With ever improving cameras and software applications, this modality has developed into an important assessment tool for ischaemic heart disease. However, the development of new perfusion tracers has been scarce. While cardiac positron emission tomography (PET) so far largely has been limited to centres with on-site cyclotron, recent developments with generator produced perfusion tracers such as rubidium-82, as well as an increasing number of PET scanners installed, may enable a larger patient flow that may supersede that of gamma camera myocardial perfusion imaging. PMID:24028171

The spatial resolution of a rotating gamma camera tomographic facility.

PubMed

Webb, S; Flower, M A; Ott, R J; Leach, M O; Inamdar, R

1983-12-01

An important feature determining the spatial resolution in transverse sections reconstructed by convolution and back-projection is the frequency filter corresponding to the convolution kernel. Equations have been derived giving the theoretical spatial resolution, for a perfect detector and noise-free data, using four filter functions. Experiments have shown that physical constraints will always limit the resolution that can be achieved with a given system. The experiments indicate that the region of the frequency spectrum between KN/2 and KN where KN is the Nyquist frequency does not contribute significantly to resolution. In order to investigate the physical effect of these filter functions, the spatial resolution of reconstructed images obtained with a GE 400T rotating gamma camera has been measured. The results obtained serve as an aid to choosing appropriate reconstruction filters for use with a rotating gamma camera system.

Acquisition of gamma camera and physiological data by computer.

PubMed

Hack, S N; Chang, M; Line, B R; Cooper, J A; Robeson, G H

1986-11-01

We have designed, implemented, and tested a new Research Data Acquisition System (RDAS) that permits a general purpose digital computer to acquire signals from both gamma camera sources and physiological signal sources concurrently. This system overcomes the limited multi-source, high speed data acquisition capabilities found in most clinically oriented nuclear medicine computers. The RDAS can simultaneously input signals from up to four gamma camera sources with a throughput of 200 kHz per source and from up to eight physiological signal sources with an aggregate throughput of 50 kHz. Rigorous testing has found the RDAS to exhibit acceptable linearity and timing characteristics. In addition, flood images obtained by this system were compared with flood images acquired by a commercial nuclear medicine computer system. National Electrical Manufacturers Association performance standards of the flood images were found to be comparable.

Gamma ray imager on the DIII-D tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pace, D. C., E-mail: pacedc@fusion.gat.com; Taussig, D.; Eidietis, N. W.

2016-04-15

A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electronsmore » in the energy range of 1–60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.« less

Gamma ray imager on the DIII-D tokamak

DOE PAGES

Pace, D. C.; Cooper, C. M.; Taussig, D.; ...

2016-04-13

A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electronsmore » in the energy range of 1- 60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. In conclusion, first measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.« less

Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics.

PubMed

Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

2017-02-03

Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that "Electron Tracking Compton Camera" (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.

A didactic experiment showing the Compton scattering by means of a clinical gamma camera.

PubMed

Amato, Ernesto; Auditore, Lucrezia; Campennì, Alfredo; Minutoli, Fabio; Cucinotta, Mariapaola; Sindoni, Alessandro; Baldari, Sergio

2017-06-01

We describe a didactic approach aimed to explain the effect of Compton scattering in nuclear medicine imaging, exploiting the comparison of a didactic experiment with a gamma camera with the outcomes from a Monte Carlo simulation of the same experimental apparatus. We employed a 99m Tc source emitting 140.5keV photons, collimated in the upper direction through two pinholes, shielded by 6mm of lead. An aluminium cylinder was placed on the source at 50mm of distance. The energy of the scattered photons was measured on the spectra acquired by the gamma camera. We observed that the gamma ray energy measured at each step of rotation gradually decreased from the characteristic energy of 140.5keV at 0° to 102.5keV at 120°. A comparison between the obtained data and the expected results from the Compton formula and from the Monte Carlo simulation revealed a full agreement within the experimental error (relative errors between -0.56% and 1.19%), given by the energy resolution of the gamma camera. Also the electron rest mass has been evaluated satisfactorily. The experiment was found useful in explaining nuclear medicine residents the phenomenology of the Compton scattering and its importance in the nuclear medicine imaging, and it can be profitably proposed during the training of medical physics residents as well. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Characterization of a small CsI(Na)-WSF-SiPM gamma camera prototype using 99mTc

NASA Astrophysics Data System (ADS)

Castro, I. F.; Soares, A. J.; Moutinho, L. M.; Ferreira, M. A.; Ferreira, R.; Combo, A.; Muchacho, F.; Veloso, J. F. C. A.

2013-03-01

A small field of view gamma camera is being developed, aiming for applications in scintimammography, sentinel lymph node detection or small animal imaging and research. The proposed wavelength-shifting fibre (WSF) gamma camera consists of two perpendicular sets of WSFs covering both sides of a CsI(Na) crystal, such that the fibres positioned at the bottom of the crystal provide the x coordinate and the ones on top the y coordinate of the gamma photon interaction point. The 2D position is given by highly sensitive photodetectors reading out each WSF and the energy information is provided by PMTs that cover the full detector area. This concept has the advantage of using N+N instead of N × N photodetectors to cover an identical imaging area, and is being applied using for the first time SiPMs. Previous studies carried out with 57Co have proved the feasibility of this concept using SiPM readout. In this work, we present experimental results from true 2D image acquisitions with a 10+10 SiPMs prototype, i.e. 10 × 10 mm2, using a parallel-hole collimator and different samples filled with 99mTc solution. The performance of the small prototype in these conditions is evaluated through the characterization of different gamma camera parameters, such as energy and spatial resolution. Ongoing advances towards a larger prototype of 100+100 SiPMs (10 × 10 cm2) are also presented.

CMOS Camera Array With Onboard Memory

NASA Technical Reports Server (NTRS)

Gat, Nahum

2009-01-01

A compact CMOS (complementary metal oxide semiconductor) camera system has been developed with high resolution (1.3 Megapixels), a USB (universal serial bus) 2.0 interface, and an onboard memory. Exposure times, and other operating parameters, are sent from a control PC via the USB port. Data from the camera can be received via the USB port and the interface allows for simple control and data capture through a laptop computer.

Laser line scan underwater imaging by complementary metal-oxide-semiconductor camera

NASA Astrophysics Data System (ADS)

He, Zhiyi; Luo, Meixing; Song, Xiyu; Wang, Dundong; He, Ning

2017-12-01

This work employs the complementary metal-oxide-semiconductor (CMOS) camera to acquire images in a scanning manner for laser line scan (LLS) underwater imaging to alleviate backscatter impact of seawater. Two operating features of the CMOS camera, namely the region of interest (ROI) and rolling shutter, can be utilized to perform image scan without the difficulty of translating the receiver above the target as the traditional LLS imaging systems have. By the dynamically reconfigurable ROI of an industrial CMOS camera, we evenly divided the image into five subareas along the pixel rows and then scanned them by changing the ROI region automatically under the synchronous illumination by the fun beams of the lasers. Another scanning method was explored by the rolling shutter operation of the CMOS camera. The fun beam lasers were turned on/off to illuminate the narrow zones on the target in a good correspondence to the exposure lines during the rolling procedure of the camera's electronic shutter. The frame synchronization between the image scan and the laser beam sweep may be achieved by either the strobe lighting output pulse or the external triggering pulse of the industrial camera. Comparison between the scanning and nonscanning images shows that contrast of the underwater image can be improved by our LLS imaging techniques, with higher stability and feasibility than the mechanically controlled scanning method.

In-situ thermal annealing of on-membrane silicon-on-insulator semiconductor-based devices after high gamma dose irradiation.

PubMed

Amor, S; André, N; Kilchytska, V; Tounsi, F; Mezghani, B; Gérard, P; Ali, Z; Udrea, F; Flandre, D; Francis, L A

2017-05-05

In this paper, we investigate the recovery of some semiconductor-based components, such as N/P-type field-effect transistors (FETs) and a complementary metal-oxide-semiconductor (CMOS) inverter, after being exposed to a high total dose of gamma ray radiation. The employed method consists mainly of a rapid, low power and in situ annealing mitigation technique by silicon-on-insulator micro-hotplates. Due to the ionizing effect of the gamma irradiation, the threshold voltages showed an average shift of -580 mV for N-channel transistors, and -360 mV for P-MOSFETs. A 4 min double-cycle annealing of components with a heater temperature up to 465 °C, corresponding to a maximum power of 38 mW, ensured partial recovery but was not sufficient for full recovery. The degradation was completely recovered after the use of a built-in high temperature annealing process, up to 975 °C for 8 min corresponding to a maximum power of 112 mW, which restored the normal operating characteristics for all devices after their irradiation.

In-situ thermal annealing of on-membrane silicon-on-insulator semiconductor-based devices after high gamma dose irradiation

NASA Astrophysics Data System (ADS)

Amor, S.; André, N.; Kilchytska, V.; Tounsi, F.; Mezghani, B.; Gérard, P.; Ali, Z.; Udrea, F.; Flandre, D.; Francis, L. A.

2017-05-01

In this paper, we investigate the recovery of some semiconductor-based components, such as N/P-type field-effect transistors (FETs) and a complementary metal-oxide-semiconductor (CMOS) inverter, after being exposed to a high total dose of gamma ray radiation. The employed method consists mainly of a rapid, low power and in situ annealing mitigation technique by silicon-on-insulator micro-hotplates. Due to the ionizing effect of the gamma irradiation, the threshold voltages showed an average shift of -580 mV for N-channel transistors, and -360 mV for P-MOSFETs. A 4 min double-cycle annealing of components with a heater temperature up to 465 °C, corresponding to a maximum power of 38 mW, ensured partial recovery but was not sufficient for full recovery. The degradation was completely recovered after the use of a built-in high temperature annealing process, up to 975 °C for 8 min corresponding to a maximum power of 112 mW, which restored the normal operating characteristics for all devices after their irradiation.

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

NASA Astrophysics Data System (ADS)

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

2013-04-01

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

Performance Test Data Analysis of Scintillation Cameras

NASA Astrophysics Data System (ADS)

Demirkaya, Omer; Mazrou, Refaat Al

2007-10-01

In this paper, we present a set of image analysis tools to calculate the performance parameters of gamma camera systems from test data acquired according to the National Electrical Manufacturers Association NU 1-2001 guidelines. The calculation methods are either completely automated or require minimal user interaction; minimizing potential human errors. The developed methods are robust with respect to varying conditions under which these tests may be performed. The core algorithms have been validated for accuracy. They have been extensively tested on images acquired by the gamma cameras from different vendors. All the algorithms are incorporated into a graphical user interface that provides a convenient way to process the data and report the results. The entire application has been developed in MATLAB programming environment and is compiled to run as a stand-alone program. The developed image analysis tools provide an automated, convenient and accurate means to calculate the performance parameters of gamma cameras and SPECT systems. The developed application is available upon request for personal or non-commercial uses. The results of this study have been partially presented in Society of Nuclear Medicine Annual meeting as an InfoSNM presentation.

Assessment of right ventricular function with nonimaging first pass ventriculography and comparison of results with gamma camera studies.

PubMed

Zhang, Z; Liu, X J; Liu, Y Z; Lu, P; Crawley, J C; Lahiri, A

1990-08-01

A new technique has been developed for measuring right ventricular function by nonimaging first pass ventriculography. The right ventricular ejection fraction (RVEF) obtained by non-imaging first pass ventriculography was compared with that obtained by gamma camera first pass and equilibrium ventriculography. The data has demonstrated that the correlation of RVEFs obtained by the nonimaging nuclear cardiac probe and by gamma camera first pass ventriculography in 15 subjects was comparable (r = 0.93). There was also a good correlation between RVEFs obtained by the nonimaging nuclear probe and by equilibrium gated blood pool studies in 33 subjects (r = 0.89). RVEF was significantly reduced in 15 patients with right ventricular and/or inferior myocardial infarction compared to normal subjects (28 +/- 9% v. 45 +/- 9%). The data suggests that nonimaging probes may be used for assessing right ventricular function accurately.

Emission computerized axial tomography from multiple gamma-camera views using frequency filtering.

PubMed

Pelletier, J L; Milan, C; Touzery, C; Coitoux, P; Gailliard, P; Budinger, T F

1980-01-01

Emission computerized axial tomography is achievable in any nuclear medicine department from multiple gamma camera views. Data are collected by rotating the patient in front of the camera. A simple fast algorithm is implemented, known as the convolution technique: first the projection data are Fourier transformed and then an original filter designed for optimizing resolution and noise suppression is applied; finally the inverse transform of the latter operation is back-projected. This program, which can also take into account the attenuation for single photon events, was executed with good results on phantoms and patients. We think that it can be easily implemented for specific diagnostic problems.

The Advanced Gamma-ray Imaging System (AGIS) - Camera Electronics Development

NASA Astrophysics Data System (ADS)

Tajima, Hiroyasu; Bechtol, K.; Buehler, R.; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Hanna, D.; Horan, D.; Humensky, B.; Karlsson, N.; Kieda, D.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Mukherjee, R.; Ong, R.; Otte, N.; Quinn, J.; Schroedter, M.; Swordy, S.; Wagner, R.; Wakely, S.; Weinstein, A.; Williams, D.; Camera Working Group; AGIS Collaboration

2010-03-01

AGIS, a next-generation imaging atmospheric Cherenkov telescope (IACT) array, aims to achieve a sensitivity level of about one milliCrab for gamma-ray observations in the energy band of 50 GeV to 100 TeV. Achieving this level of performance will require on the order of 50 telescopes with perhaps as many as 1M total electronics channels. The larger scale of AGIS requires a very different approach from the currently operating IACTs, with lower-cost and lower-power electronics incorporated into camera modules designed for high reliability and easy maintenance. Here we present the concept and development status of the AGIS camera electronics.

Multi-spectral imaging with infrared sensitive organic light emitting diode

PubMed Central

Kim, Do Young; Lai, Tzung-Han; Lee, Jae Woong; Manders, Jesse R.; So, Franky

2014-01-01

Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions. PMID:25091589

Multi-spectral imaging with infrared sensitive organic light emitting diode

NASA Astrophysics Data System (ADS)

Kim, Do Young; Lai, Tzung-Han; Lee, Jae Woong; Manders, Jesse R.; So, Franky

2014-08-01

Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions.

Camera Development for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Moncada, Roberto Jose

2017-01-01

With the Cherenkov Telescope Array (CTA), the very-high-energy gamma-ray universe, between 30 GeV and 300 TeV, will be probed at an unprecedented resolution, allowing deeper studies of known gamma-ray emitters and the possible discovery of new ones. This exciting project could also confirm the particle nature of dark matter by looking for the gamma rays produced by self-annihilating weakly interacting massive particles (WIMPs). The telescopes will use the imaging atmospheric Cherenkov technique (IACT) to record Cherenkov photons that are produced by the gamma-ray induced extensive air shower. One telescope design features dual-mirror Schwarzschild-Couder (SC) optics that allows the light to be finely focused on the high-resolution silicon photomultipliers of the camera modules starting from a 9.5-meter primary mirror. Each camera module will consist of a focal plane module and front-end electronics, and will have four TeV Array Readout with GSa/s Sampling and Event Trigger (TARGET) chips, giving them 64 parallel input channels. The TARGET chip has a self-trigger functionality for readout that can be used in higher logic across camera modules as well as across individual telescopes, which will each have 177 camera modules. There will be two sites, one in the northern and the other in the southern hemisphere, for full sky coverage, each spanning at least one square kilometer. A prototype SC telescope is currently under construction at the Fred Lawrence Whipple Observatory in Arizona. This work was supported by the National Science Foundation's REU program through NSF award AST-1560016.

Effect of an external magnetic field on the mass attenuation coefficients of p-Si and n-Si

NASA Astrophysics Data System (ADS)

Yılmaz, D.; Önder, P.

2018-05-01

In this study, the mass attenuation coefficients of p-Si and n-Si semiconductor samples have been determined in an external magnetic field. The semiconductor samples were located to the external magnetic field of intensities 0.2 T, 0.4 T, 0.6 T and 0.8 T. The samples were bombarded by 59.5 keV, 80.1 keV, 121.8 keV and 244.7 keV gamma-rays emitted from Am241, Ba133 and Eu152 radioactive sources. The transmitted photons were detected by a CdTe detector. It was observed that the mass attenuation coefficients of p-Si and n-Si semiconductor samples decrease with increasing gamma-ray energy. Also, the mass attenuation coefficients of the samples increase with applying magnetic field intensity.

Sentinel node detection in early breast cancer with intraoperative portable gamma camera: UK experience.

PubMed

Ghosh, Debashis; Michalopoulos, Nikolaos V; Davidson, Timothy; Wickham, Fred; Williams, Norman R; Keshtgar, Mohammed R

2017-04-01

Access to nuclear medicine department for sentinel node imaging remains an issue in number of hospitals in the UK and many parts of the world. Sentinella ® is a portable imaging camera used intra-operatively to produce real time visual localisation of sentinel lymph nodes. Sentinella ® was tested in a controlled laboratory environment at our centre and we report our experience on the first use of this technology from UK. Moreover, preoperative scintigrams of the axilla were obtained in 144 patients undergoing sentinel node biopsy using conventional gamma camera. Sentinella ® scans were done intra-operatively to correlate with the pre-operative scintigram and to determine presence of any residual hot node after the axilla was deemed to be clear based on the silence of the hand held gamma probe. Sentinella ® detected significantly more nodes compared with CGC (p < 0.0001). Sentinella ® picked up extra nodes in 5/144 cases after the axilla was found silent using hand held gamma probe. In 2/144 cases, extra nodes detected by Sentinella ® confirmed presence of tumour cells that led to a complete axillary clearance. Sentinella ® is a reliable technique for intra-operative localisation of radioactive nodes. It provides increased nodal visualisation rates compared to static scintigram imaging and proves to be an important tool for harvesting all hot sentinel nodes. This portable gamma camera can definitely replace the use of conventional lymphoscintigrams saving time and money both for patients and the health system. Copyright © 2016 Elsevier Ltd. All rights reserved.

SeHCAT retention values as measured with a collimated and an uncollimated gamma camera: a method comparison study.

PubMed

Wright, James W; Lovell, Lesley A; Gemmell, Howard G; McKiddie, Fergus; Staff, Roger T

2013-07-01

TauroH-23-(Se) selena-25-homocholic acid retention values are used in the diagnosis of bile acid malabsorption. The standard method for measuring values is with an uncollimated gamma camera, which can create some logistic difficulties, with other background sources of activity, which are irrelevant when a collimator is used, becoming significant. In this study we compare the retention values obtained with a collimated and an uncollimated gamma camera in phantoms and in 23 patients. Bland-Altman plots were created using the data, which showed a mean bias in retention of 0.10% in the phantom study and 0.55% in the patient study between methods. A Wilcoxon signed-rank test with the null hypothesis of zero median difference between uncollimated and collimated methods was not statistically significant to P values less than 0.05 in the patient and phantom studies. In the patient study, on using a fixed boundary of retention (10%) between positive and negative status, the status of one patient was changed from negative (12%) to positive (9%). We conclude that measurement of retention with a collimated gamma camera is similar but not identical to that of uncollimated values. The clinical significance of this shift is unclear, as the threshold of significance and the method of integrating this measure with other clinical factors into management remain unclear.

Radiation dosimetry properties of smartphone CMOS sensors.

PubMed

Van Hoey, Olivier; Salavrakos, Alexia; Marques, Antonio; Nagao, Alexandre; Willems, Ruben; Vanhavere, Filip; Cauwels, Vanessa; Nascimento, Luana F

2016-03-01

During the past years, several smartphone applications have been developed for radiation detection. These applications measure radiation using the smartphone camera complementary metal-oxide-semiconductor sensor. They are potentially useful for data collection and personal dose assessment in case of a radiological incident. However, it is important to assess these applications. Six applications were tested by means of irradiations with calibrated X-ray and gamma sources. It was shown that the measurement stabilises only after at least 10-25 min. All applications exhibited a flat dose rate response in the studied ambient dose equivalent range from 2 to 1000 μSv h(-1). Most applications significantly over- or underestimate the dose rate or are not calibrated in terms of dose rate. A considerable energy dependence was observed below 100 keV but not for the higher energy range more relevant for incident scenarios. Photon impact angle variation gave a measured signal variation of only about 10 %. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Gallbladder radionuclide scan (image)

MedlinePlus

... gallbladder radionuclide scan is performed by injecting a tracer (radioactive chemical) into the bloodstream. A gamma camera ... detect the gamma rays being emitted from the tracer, and the image of where the tracer is ...

"Stereo Compton cameras" for the 3-D localization of radioisotopes

NASA Astrophysics Data System (ADS)

Takeuchi, K.; Kataoka, J.; Nishiyama, T.; Fujita, T.; Kishimoto, A.; Ohsuka, S.; Nakamura, S.; Adachi, S.; Hirayanagi, M.; Uchiyama, T.; Ishikawa, Y.; Kato, T.

2014-11-01

The Compton camera is a viable and convenient tool used to visualize the distribution of radioactive isotopes that emit gamma rays. After the nuclear disaster in Fukushima in 2011, there is a particularly urgent need to develop "gamma cameras", which can visualize the distribution of such radioisotopes. In response, we propose a portable Compton camera, which comprises 3-D position-sensitive GAGG scintillators coupled with thin monolithic MPPC arrays. The pulse-height ratio of two MPPC-arrays allocated at both ends of the scintillator block determines the depth of interaction (DOI), which dramatically improves the position resolution of the scintillation detectors. We report on the detailed optimization of the detector design, based on Geant4 simulation. The results indicate that detection efficiency reaches up to 0.54%, or more than 10 times that of other cameras being tested in Fukushima, along with a moderate angular resolution of 8.1° (FWHM). By applying the triangular surveying method, we also propose a new concept for the stereo measurement of gamma rays by using two Compton cameras, thus enabling the 3-D positional measurement of radioactive isotopes for the first time. From one point source simulation data, we ensured that the source position and the distance to the same could be determined typically to within 2 meters' accuracy and we also confirmed that more than two sources are clearly separated by the event selection from two point sources of simulation data.

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

PubMed

Agostini, Denis; Marie, Pierre-Yves; Ben-Haim, Simona; Rouzet, François; Songy, Bernard; Giordano, Alessandro; Gimelli, Alessia; Hyafil, Fabien; Sciagrà, Roberto; Bucerius, Jan; Verberne, Hein J; Slart, Riemer H J A; Lindner, Oliver; Übleis, Christopher; Hacker, Marcus

2016-12-01

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

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

PubMed

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

2014-01-01

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

Experimental comparison of high-density scintillators for EMCCD-based gamma ray imaging

NASA Astrophysics Data System (ADS)

Heemskerk, Jan W. T.; Kreuger, Rob; Goorden, Marlies C.; Korevaar, Marc A. N.; Salvador, Samuel; Seeley, Zachary M.; Cherepy, Nerine J.; van der Kolk, Erik; Payne, Stephen A.; Dorenbos, Pieter; Beekman, Freek J.

2012-07-01

Detection of x-rays and gamma rays with high spatial resolution can be achieved with scintillators that are optically coupled to electron-multiplying charge-coupled devices (EMCCDs). These can be operated at typical frame rates of 50 Hz with low noise. In such a set-up, scintillation light within each frame is integrated after which the frame is analyzed for the presence of scintillation events. This method allows for the use of scintillator materials with relatively long decay times of a few milliseconds, not previously considered for use in photon-counting gamma cameras, opening up an unexplored range of dense scintillators. In this paper, we test CdWO4 and transparent polycrystalline ceramics of Lu2O3:Eu and (Gd,Lu)2O3:Eu as alternatives to currently used CsI:Tl in order to improve the performance of EMCCD-based gamma cameras. The tested scintillators were selected for their significantly larger cross-sections at 140 keV (99mTc) compared to CsI:Tl combined with moderate to good light yield. A performance comparison based on gamma camera spatial and energy resolution was done with all tested scintillators having equal (66%) interaction probability at 140 keV. CdWO4, Lu2O3:Eu and (Gd,Lu)2O3:Eu all result in a significantly improved spatial resolution over CsI:Tl, albeit at the cost of reduced energy resolution. Lu2O3:Eu transparent ceramic gives the best spatial resolution: 65 µm full-width-at-half-maximum (FWHM) compared to 147 µm FWHM for CsI:Tl. In conclusion, these ‘slow’ dense scintillators open up new possibilities for improving the spatial resolution of EMCCD-based scintillation cameras.

Pulse-height defect due to electron interaction in dead layers of Ge/Li/ gamma-ray detectors

NASA Technical Reports Server (NTRS)

Larsen, R. N.; Strauss, M. G.

1969-01-01

Study shows the pulse-height degradation of gamma ray spectra in germanium/lithium detectors to be due to electron interaction in the dead layers that exist in all semiconductor detectors. A pulse shape discrimination technique identifies and eliminates these defective pulses.

Dual mode stereotactic localization method and application

DOEpatents

Keppel, Cynthia E.; Barbosa, Fernando Jorge; Majewski, Stanislaw

2002-01-01

The invention described herein combines the structural digital X-ray image provided by conventional stereotactic core biopsy instruments with the additional functional metabolic gamma imaging obtained with a dedicated compact gamma imaging mini-camera. Before the procedure, the patient is injected with an appropriate radiopharmaceutical. The radiopharmaceutical uptake distribution within the breast under compression in a conventional examination table expressed by the intensity of gamma emissions is obtained for comparison (co-registration) with the digital mammography (X-ray) image. This dual modality mode of operation greatly increases the functionality of existing stereotactic biopsy devices by yielding a much smaller number of false positives than would be produced using X-ray images alone. The ability to obtain both the X-ray mammographic image and the nuclear-based medicine gamma image using a single device is made possible largely through the use of a novel, small and movable gamma imaging camera that permits its incorporation into the same table or system as that currently utilized to obtain X-ray based mammographic images for localization of lesions.

Estimation of bone mineral content using gamma camera: A real possibility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levy, L.M.; Hoory, S.; Bandyopadhyay, D.

1985-05-01

Osteopenia and Osteoporosis are the diseases related to loss of bone minerals. At present, dual photon absorptiometry using a dedicated specially built scanner along with a very high source of Gd-153 is being used as a diagnostic tool for the early detection of bone loss. The present study was undertaken to explore the possibility that gamma cameras which are widely available in all Nuclear Medicine departments could be used successfully to evaluate bone mineral content. A Siemens LFOV gamma camera equipped with a converging collimator was used for this purpose. A fixed source (100 mCi) of Gd-153 was placed atmore » the focal point of the collimator. A series of calcium chloride solutions of varying concentrations in plastic vials were placed near the center of the collimator and imaged both in air and water. Both 44 Kev and 100 Kev images were digitized in 128 x 128 matrices and processed in a CD and A Delta system attached to a VAX 11-750 computer. Uniformity corrections for each field of view were applied and the attenuation coefficients of calcium chloride for both peaks of Gd-153 were evaluated. In addition, due to the high count rate, corrections for the dead time losses were also found to be essential. An excellent concordance between the estimated Calcium contents and that actually present were obtained by this technic. In conclusion, use of gamma camera for the routine evaluation of Osteoporosis appears to be highly promising and worth pursuing.« less

Fast Pb-glass neutron-to-light converter for ICF (Inertial Confinement Fusion) target burn history measurements

NASA Astrophysics Data System (ADS)

Lerche, R. A.; Cable, M. D.; Phillion, D. W.

1990-09-01

We are developing a streak camera based instrument to diagnose the fusion reaction rate (burn history) within laser-driven ICF targets filled with D-T fuel. Recently, we attempted measurements using the 16.7 MeV gamma ray emitted in the T(d,gamma)He(5) fusion reaction. Pb glass which has a large cross section for pair production acts as a gamma-ray-to-light converter. Gamma rays interact within the glass to form electron-positron pairs that produce large amounts (1000 photons/gamma ray) of prompt (less than 10 ps) Cerenkov light as they slow down. In our experimental instrument, an f/10 Cassegrain telescope optically couples light produced within the converter to a streak camera having 20-ps resolution. Experiments using high-yield (10(exp 13) D-T neutrons), direct-drive targets at Nova produced good signals with widths of 200 ps. Time-of-flight measurements show the signals to be induced by neutrons rather than gamma rays. The Pb glass appears to act as a fast neutron-to-light converter. We continue to study the interactions process and the possibility of using the 16.7 MeV gamma rays for burn time measurements.

Testing FLUKA on neutron activation of Si and Ge at nuclear research reactor using gamma spectroscopy

NASA Astrophysics Data System (ADS)

Bazo, J.; Rojas, J. M.; Best, S.; Bruna, R.; Endress, E.; Mendoza, P.; Poma, V.; Gago, A. M.

2018-03-01

Samples of two characteristic semiconductor sensor materials, silicon and germanium, have been irradiated with neutrons produced at the RP-10 Nuclear Research Reactor at 4.5 MW. Their radionuclides photon spectra have been measured with high resolution gamma spectroscopy, quantifying four radioisotopes (28Al, 29Al for Si and 75Ge and 77Ge for Ge). We have compared the radionuclides production and their emission spectrum data with Monte Carlo simulation results from FLUKA. Thus we have tested FLUKA's low energy neutron library (ENDF/B-VIIR) and decay photon scoring with respect to the activation of these semiconductors. We conclude that FLUKA is capable of predicting relative photon peak amplitudes, with gamma intensities greater than 1%, of produced radionuclides with an average uncertainty of 13%. This work allows us to estimate the corresponding systematic error on neutron activation simulation studies of these sensor materials.

Applications of iQID cameras

NASA Astrophysics Data System (ADS)

Han, Ling; Miller, Brian W.; Barrett, Harrison H.; Barber, H. Bradford; Furenlid, Lars R.

2017-09-01

iQID is an intensified quantum imaging detector developed in the Center for Gamma-Ray Imaging (CGRI). Originally called BazookaSPECT, iQID was designed for high-resolution gamma-ray imaging and preclinical gamma-ray single-photon emission computed tomography (SPECT). With the use of a columnar scintillator, an image intensifier and modern CCD/CMOS sensors, iQID cameras features outstanding intrinsic spatial resolution. In recent years, many advances have been achieved that greatly boost the performance of iQID, broadening its applications to cover nuclear and particle imaging for preclinical, clinical and homeland security settings. This paper presents an overview of the recent advances of iQID technology and its applications in preclinical and clinical scintigraphy, preclinical SPECT, particle imaging (alpha, neutron, beta, and fission fragment), and digital autoradiography.

A fast algorithm for computer aided collimation gamma camera (CACAO)

NASA Astrophysics Data System (ADS)

Jeanguillaume, C.; Begot, S.; Quartuccio, M.; Douiri, A.; Franck, D.; Pihet, P.; Ballongue, P.

2000-08-01

The computer aided collimation gamma camera is aimed at breaking down the resolution sensitivity trade-off of the conventional parallel hole collimator. It uses larger and longer holes, having an added linear movement at the acquisition sequence. A dedicated algorithm including shift and sum, deconvolution, parabolic filtering and rotation is described. Examples of reconstruction are given. This work shows that a simple and fast algorithm, based on a diagonal dominant approximation of the problem can be derived. Its gives a practical solution to the CACAO reconstruction problem.

Determination of uranium isotopes in food and environmental samples by different techniques: a comparison.

PubMed

Forte, M; Rusconi, R; Margini, C; Abbate, G; Maltese, S; Badalamenti, P; Bellinzona, S

2001-01-01

The uranium concentration in 59 samples of bottled and tap water, mainly from northern Italy, was measured by different techniques. Results obtained by inductively coupled plasma mass spectrometry (ICP-MS), semiconductor alpha spectrometry and low level liquid scintillation counting with alpha/beta discrimination (LSC) have been compared. High resolution gamma spectrometry and semiconductor alpha spectrometry have been used to analyse uranium in a variety of organic and inorganic samples. Isotopic secular equilibrium in the 238U series may be lacking or hidden by auto-absorption phenomena, so caution should be used in evaluating gamma spectrometry data. Alpha spectrometry has also been used to ascertain the possible pollution from depleted uranium in the environment.

SHOK—The First Russian Wide-Field Optical Camera in Space

NASA Astrophysics Data System (ADS)

Lipunov, V. M.; Gorbovskoy, E. S.; Kornilov, V. G.; Panasyuk, M. I.; Amelushkin, A. M.; Petrov, V. L.; Yashin, I. V.; Svertilov, S. I.; Vedenkin, N. N.

2018-02-01

Onboard the spacecraft Lomonosov is established two fast, fixed, very wide-field cameras SHOK. The main goal of this experiment is the observation of GRB optical emission before, synchronously, and after the gamma-ray emission. The field of view of each of the cameras is placed in the gamma-ray burst detection area of other devices located onboard the "Lomonosov" spacecraft. SHOK provides measurements of optical emissions with a magnitude limit of ˜ 9-10m on a single frame with an exposure of 0.2 seconds. The device is designed for continuous sky monitoring at optical wavelengths in the very wide field of view (1000 square degrees each camera), detection and localization of fast time-varying (transient) optical sources on the celestial sphere, including provisional and synchronous time recording of optical emissions from the gamma-ray burst error boxes, detected by the BDRG device and implemented by a control signal (alert trigger) from the BDRG. The Lomonosov spacecraft has two identical devices, SHOK1 and SHOK2. The core of each SHOK device is a fast-speed 11-Megapixel CCD. Each of the SHOK devices represents a monoblock, consisting of a node observations of optical emission, the electronics node, elements of the mechanical construction, and the body.

The Si/CdTe semiconductor camera of the ASTRO-H Hard X-ray Imager (HXI)

NASA Astrophysics Data System (ADS)

Sato, Goro; Hagino, Kouichi; Watanabe, Shin; Genba, Kei; Harayama, Atsushi; Kanematsu, Hironori; Kataoka, Jun; Katsuragawa, Miho; Kawaharada, Madoka; Kobayashi, Shogo; Kokubun, Motohide; Kuroda, Yoshikatsu; Makishima, Kazuo; Masukawa, Kazunori; Mimura, Taketo; Miyake, Katsuma; Murakami, Hiroaki; Nakano, Toshio; Nakazawa, Kazuhiro; Noda, Hirofumi; Odaka, Hirokazu; Onishi, Mitsunobu; Saito, Shinya; Sato, Rie; Sato, Tamotsu; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shin`ichiro; Yuasa, Takayuki

2016-09-01

The Hard X-ray Imager (HXI) is one of the instruments onboard the ASTRO-H mission [1-4] to be launched in early 2016. The HXI is the focal plane detector of the hard X-ray reflecting telescope that covers an energy range from 5 to 80 keV. It will execute observations of astronomical objects with a sensitivity for point sources as faint as 1/100,000 of the Crab nebula at > 10 keV. The HXI camera - the imaging part of the HXI - is realized by a hybrid semiconductor detector system that consists of silicon (Si) and cadmium telluride (CdTe) semiconductor detectors. Here, we present the final design of the HXI camera and report on the development of the flight model. The camera is composed of four layers of Double-sided Silicon Strip Detectors (DSSDs) and one layer of CdTe Double-sided Strip Detector (CdTe-DSD), each with an imaging area of 32 mm×32 mm. The strip pitch of the Si and CdTe sensors is 250 μm, and the signals from all 1280 strips are processed by 40 Application Specified Integrated Circuits (ASICs) developed for the HXI. The five layers of sensors are vertically stacked with a 4 mm spacing to increase the detection efficiency. The thickness of the sensors is 0.5 mm for the Si, and 0.75 mm for the CdTe. In this configuration, soft X-ray photons will be absorbed in the Si part, while hard X-ray photons will go through the Si part and will be detected in the CdTe part. The design of the sensor trays, peripheral circuits, power connections, and readout schemes are also described. The flight models of the HXI camera have been manufactured, tested and installed in the HXI instrument and then on the satellite.

Gamma Ray Burst Optical Counterpart Search Experiment (GROCSE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, H.S.; Ables, E.; Bionta, R.M.

GROCSE (Gamma-Ray Optical Counterpart Search Experiments) is a system of automated telescopes that search for simultaneous optical activity associated with gamma ray bursts in response to real-time burst notifications provided by the BATSE/BACODINE network. The first generation system, GROCSE 1, is sensitive down to Mv {approximately} 8.5 and requires an average of 12 seconds to obtain the first images of the gamma ray burst error box defined by the BACODINE trigger. The collaboration is now constructing a second generation system which has a 4 second slewing time and can reach Mv {approximately} 14 with a 5 second exposure. GROCSE 2more » consists of 4 cameras on a single mount. Each camera views the night sky through a commercial Canon lens (f/1.8, focal length 200 mm) and utilizes a 2K x 2K Loral CCD. Light weight and low noise custom readout electronics were designed and fabricated for these CCDs. The total field of view of the 4 cameras is 17.6 x 17.6 {degree}. GROCSE II will be operated by the end of 1995. In this paper, the authors present an overview of the GROCSE system and the results of measurements with a GROCSE 2 prototype unit.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halama, J.

2016-06-15

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Impact of intense x-ray pulses on a NaI(Tl)-based gamma camera

NASA Astrophysics Data System (ADS)

Koppert, W. J. C.; van der Velden, S.; Steenbergen, J. H. L.; de Jong, H. W. A. M.

2018-03-01

In SPECT/CT systems x-ray and γ-ray imaging is performed sequentially. Simultaneous acquisition may have advantages, for instance in interventional settings. However, this may expose a gamma camera to relatively high x-ray doses and deteriorate its functioning. We studied the NaI(Tl) response to x-ray pulses with a photodiode, PMT and gamma camera, respectively. First, we exposed a NaI(Tl)-photodiode assembly to x-ray pulses to investigate potential crystal afterglow. Next, we exposed a NaI(Tl)-PMT assembly to 10 ms LED pulses (mimicking x-ray pulses) and measured the response to flashing LED probe-pulses (mimicking γ-pulses). We then exposed the assembly to x-ray pulses, with detector entrance doses of up to 9 nGy/pulse, and analysed the response for γ-pulse variations. Finally, we studied the response of a Siemens Diacam gamma camera to γ-rays while exposed to x-ray pulses. X-ray exposure of the crystal, read out with a photodiode, revealed 15% afterglow fraction after 3 ms. The NaI(Tl)-PMT assembly showed disturbances up to 10 ms after 10 ms LED exposure. After x-ray exposure however, responses showed elevated baselines, with 60 ms decay-time. Both for x-ray and LED exposure and after baseline subtraction, probe-pulse analysis revealed disturbed pulse height measurements shortly after exposure. X-ray exposure of the Diacam corroborated the elementary experiments. Up to 50 ms after an x-ray pulse, no events are registered, followed by apparent energy elevations up to 100 ms after exposure. Limiting the dose to 0.02 nGy/pulse prevents detrimental effects. Conventional gamma cameras exhibit substantial dead-time and mis-registration of photon energies up to 100 ms after intense x-ray pulses. This is due PMT limitations and due to afterglow in the crystal. Using PMTs with modified circuitry, we show that deteriorative afterglow effects can be reduced without noticeable effects on the PMT performance, up to x-ray pulse doses of 1 nGy.

Total-dose radiation effects data for semiconductor devices (1989 supplement)

NASA Technical Reports Server (NTRS)

Martin, Keith E.; Coss, James R.; Goben, Charles A.; Shaw, David C.; Farmanesh, Sam; Davarpanah, Michael M.; Craft, Leroy H.; Price, William E.

1990-01-01

Steady state, total dose radiation test data are provided for electronic designers and other personnel using semiconductor devices in a radiation environment. The data are presented in graphic and narrative formats. Two primary radiation source types were used: Cobalt-60 gamma rays and a Dynamitron electron accelerator capable of delivering 2.5 MeV electrons at a steady rate.

High resolution scintillation detector with semiconductor readout

DOEpatents

Levin, Craig S.; Hoffman, Edward J.

2000-01-01

A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

Prompt-gamma monitoring in hadrontherapy: A review

NASA Astrophysics Data System (ADS)

Krimmer, J.; Dauvergne, D.; Létang, J. M.; Testa, É.

2018-01-01

Secondary radiation emission induced by nuclear reactions is correlated to the path of ions in matter. Therefore, such penetrating radiation can be used for in vivo control of hadrontherapy treatments, for which the primary beam is absorbed inside the patient. Among secondary radiations, prompt-gamma rays were proposed for real-time verification of ion range. Such a verification is a desired condition to reduce uncertainties in treatment planning. For more than a decade, efforts have been undertaken worldwide to promote prompt-gamma-based devices to be used in clinical conditions. Dedicated cameras are necessary to overcome the challenges of a broad- and high-energy distribution, a large background, high instantaneous count rates, and compatibility constraints with patient irradiation. Several types of prompt-gamma imaging devices have been proposed, that are either physically-collimated or electronically collimated (Compton cameras). Clinical tests are now undergoing. Meanwhile, other methods than direct prompt-gamma imaging were proposed, that are based on specific counting using either time-of-flight or photon energy measurements. In the present article, we make a review and discuss the state of the art for all techniques using prompt-gamma detection to improve the quality assurance in hadrontherapy.

New Technology CZT Detectors for High-Energy Flare Spectroscopy: The Room Temperature Semiconductor Spectrometer for JAWSAT

NASA Technical Reports Server (NTRS)

Vestrand, W. Thomas

1999-01-01

The goal of our Room Temperature Semiconductor Spectrometer (RTeSS) project is to develop a small high-energy solar flare spectrometer employing semiconductor detectors that do not require significant cooling when used as high-energy solar flare spectrometers. Specifically, the goal is to test Cadmium Zinc Telluride (CZT) detectors with coplanar grid electrodes as x-ray and gamma-ray spectrometers and to design an experiment that can be flown as a "piggy-back" payload on a satellite mission during the next solar maximum.

Application of imaging to the atmospheric Cherenkov technique

NASA Technical Reports Server (NTRS)

Cawley, M. F.; Fegan, D. J.; Gibbs, K.; Gorham, P. W.; Hillas, A. M.; Lamb, R. C.; Liebing, D. F.; Mackeown, P. K.; Porter, N. A.; Stenger, V. J.

1985-01-01

Turver and Weekes proposed using a system of phototubes in the focal plane of a large reflector to give an air Cherenkov camera for gamma ray astronomy. Preliminary results with a 19 element camera have been reported previously. In 1983 the camera was increased to 37 pixels; it has now been routinely operated for two years. A brief physical description of the camera, its mode of operation, and the data reduction procedures are presented. The Monte Carlo simultations on which these are based on also reviewed.

Performance and field tests of a handheld Compton camera using 3-D position-sensitive scintillators coupled to multi-pixel photon counter arrays

NASA Astrophysics Data System (ADS)

Kishimoto, A.; Kataoka, J.; Nishiyama, T.; Fujita, T.; Takeuchi, K.; Okochi, H.; Ogata, H.; Kuroshima, H.; Ohsuka, S.; Nakamura, S.; Hirayanagi, M.; Adachi, S.; Uchiyama, T.; Suzuki, H.

2014-11-01

After the nuclear disaster in Fukushima, radiation decontamination has become particularly urgent. To help identify radiation hotspots and ensure effective decontamination operation, we have developed a novel Compton camera based on Ce-doped Gd3Al2Ga3O12 scintillators and multi-pixel photon counter (MPPC) arrays. Even though its sensitivity is several times better than that of other cameras being tested in Fukushima, we introduce a depth-of-interaction (DOI) method to further improve the angular resolution. For gamma rays, the DOI information, in addition to 2-D position, is obtained by measuring the pulse-height ratio of the MPPC arrays coupled to ends of the scintillator. We present the detailed performance and results of various field tests conducted in Fukushima with the prototype 2-D and DOI Compton cameras. Moreover, we demonstrate stereo measurement of gamma rays that enables measurement of not only direction but also approximate distance to radioactive hotspots.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanov, Oleg P.; Semin, Ilya A.; Potapov, Victor N.

Gamma-ray imaging is the most important way to identify unknown gamma-ray emitting objects in decommissioning, security, overcoming accidents. Over the past two decades a system for producing of gamma images in these conditions became more or less portable devices. But in recent years these systems have become the hand-held devices. This is very important, especially in emergency situations, and measurements for safety reasons. We describe the first integrated hand-held instrument for emergency and security applications. The device is based on the coded aperture image formation, position sensitive gamma-ray (X-ray) detector Medipix2 (detectors produces by X-ray Imaging Europe) and tablet computer.more » The development was aimed at creating a very low weight system with high angular resolution. We present some sample gamma-ray images by camera. Main estimated parameters of the system are the following. The field of view video channel ∼ 490 deg. The field of view gamma channel ∼ 300 deg. The sensitivity of the system with a hexagonal mask for the source of Cs-137 (Eg = 662 keV), is in units of dose D ∼ 100 mR. This option is less then order of magnitude worse than for the heavy, non-hand-held systems (e.g., gamma-camera Cartogam, by Canberra.) The angular resolution of the gamma channel for the sources of Cs-137 (Eg = 662 keV) is about 1.20 deg. (authors)« less

Precision imaging of 4.4 MeV gamma rays using a 3-D position sensitive Compton camera.

PubMed

Koide, Ayako; Kataoka, Jun; Masuda, Takamitsu; Mochizuki, Saku; Taya, Takanori; Sueoka, Koki; Tagawa, Leo; Fujieda, Kazuya; Maruhashi, Takuya; Kurihara, Takuya; Inaniwa, Taku

2018-05-25

Imaging of nuclear gamma-ray lines in the 1-10 MeV range is far from being established in both medical and physical applications. In proton therapy, 4.4 MeV gamma rays are emitted from the excited nucleus of either 12 C* or 11 B* and are considered good indicators of dose delivery and/or range verification. Further, in gamma-ray astronomy, 4.4 MeV gamma rays are produced by cosmic ray interactions in the interstellar medium, and can thus be used to probe nucleothynthesis in the universe. In this paper, we present a high-precision image of 4.4 MeV gamma rays taken by newly developed 3-D position sensitive Compton camera (3D-PSCC). To mimic the situation in proton therapy, we first irradiated water, PMMA and Ca(OH)2 with a 70 MeV proton beam, then we identified various nuclear lines with the HPGe detector. The 4.4 MeV gamma rays constitute a broad peak, including single and double escape peaks. Thus, by setting an energy window of 3D-PSCC from 3 to 5 MeV, we show that a gamma ray image sharply concentrates near the Bragg peak, as expected from the minimum energy threshold and sharp peak profile in the cross section of 12 C(p,p) 12 C*.

Measurement of total-body cobalt-57 vitamin B12 absorption with a gamma camera.

PubMed

Cardarelli, J A; Slingerland, D W; Burrows, B A; Miller, A

1985-08-01

Previously described techniques for the measurement of the absorption of [57Co]vitamin B12 by total-body counting have required an iron room equipped with scanning or multiple detectors. The present study uses simplifying modifications which make the technique more available and include the use of static geometry, the measurement of body thickness to correct for attenuation, a simple formula to convert the capsule-in-air count to a 100% absorption count, and finally the use of an adequately shielded gamma camera obviating the need of an iron room.

Radiation hardness of β-Ga2O3 metal-oxide-semiconductor field-effect transistors against gamma-ray irradiation

NASA Astrophysics Data System (ADS)

Wong, Man Hoi; Takeyama, Akinori; Makino, Takahiro; Ohshima, Takeshi; Sasaki, Kohei; Kuramata, Akito; Yamakoshi, Shigenobu; Higashiwaki, Masataka

2018-01-01

The effects of ionizing radiation on β-Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated. A gamma-ray tolerance as high as 1.6 MGy(SiO2) was demonstrated for the bulk Ga2O3 channel by virtue of weak radiation effects on the MOSFETs' output current and threshold voltage. The MOSFETs remained functional with insignificant hysteresis in their transfer characteristics after exposure to the maximum cumulative dose. Despite the intrinsic radiation hardness of Ga2O3, radiation-induced gate leakage and drain current dispersion ascribed respectively to dielectric damage and interface charge trapping were found to limit the overall radiation hardness of these devices.

R&D 100, 2016: Ultrafast X-ray Imager

ScienceCinema

Porter, John; Claus, Liam; Sanchez, Marcos; Robertson, Gideon; Riley, Nathan; Rochau, Greg

2018-06-13

The Ultrafast X-ray Imager is a solid-state camera capable of capturing a sequence of images with user-selectable exposure times as short as 2 billionths of a second. Using 3D semiconductor integration techniques to form a hybrid chip, this camera was developed to enable scientists to study the heating and compression of fusion targets in the quest to harness the energy process that powers the stars.

R&D 100, 2016: Ultrafast X-ray Imager

DOE Office of Scientific and Technical Information (OSTI.GOV)

Porter, John; Claus, Liam; Sanchez, Marcos

The Ultrafast X-ray Imager is a solid-state camera capable of capturing a sequence of images with user-selectable exposure times as short as 2 billionths of a second. Using 3D semiconductor integration techniques to form a hybrid chip, this camera was developed to enable scientists to study the heating and compression of fusion targets in the quest to harness the energy process that powers the stars.

Flexible mini gamma camera reconstructions of extended sources using step and shoot and list mode.

PubMed

Gardiazabal, José; Matthies, Philipp; Vogel, Jakob; Frisch, Benjamin; Navab, Nassir; Ziegler, Sibylle; Lasser, Tobias

2016-12-01

Hand- and robot-guided mini gamma cameras have been introduced for the acquisition of single-photon emission computed tomography (SPECT) images. Less cumbersome than whole-body scanners, they allow for a fast acquisition of the radioactivity distribution, for example, to differentiate cancerous from hormonally hyperactive lesions inside the thyroid. This work compares acquisition protocols and reconstruction algorithms in an attempt to identify the most suitable approach for fast acquisition and efficient image reconstruction, suitable for localization of extended sources, such as lesions inside the thyroid. Our setup consists of a mini gamma camera with precise tracking information provided by a robotic arm, which also provides reproducible positioning for our experiments. Based on a realistic phantom of the thyroid including hot and cold nodules as well as background radioactivity, the authors compare "step and shoot" (SAS) and continuous data (CD) acquisition protocols in combination with two different statistical reconstruction methods: maximum-likelihood expectation-maximization (ML-EM) for time-integrated count values and list-mode expectation-maximization (LM-EM) for individually detected gamma rays. In addition, the authors simulate lower uptake values by statistically subsampling the experimental data in order to study the behavior of their approach without changing other aspects of the acquired data. All compared methods yield suitable results, resolving the hot nodules and the cold nodule from the background. However, the CD acquisition is twice as fast as the SAS acquisition, while yielding better coverage of the thyroid phantom, resulting in qualitatively more accurate reconstructions of the isthmus between the lobes. For CD acquisitions, the LM-EM reconstruction method is preferable, as it yields comparable image quality to ML-EM at significantly higher speeds, on average by an order of magnitude. This work identifies CD acquisition protocols combined with LM-EM reconstruction as a prime candidate for the wider introduction of SPECT imaging with flexible mini gamma cameras in the clinical practice.

AIRWAY IDENTIFICATION WITHIN PLANAR GAMMA CAMERA IMAGES USING COMPUTER MODELS OF LUNG MORPHOLOGY

EPA Science Inventory

The quantification of inhaled aerosols could be improved if a more comprehensive assessment of their spatial distribution patterns among lung airways were obtained. A common technique for quantifying particle deposition in human lungs is with planar gamma scintigraphy. However, t...

Affordable CZT SPECT with dose-time minimization (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hugg, James W.; Harris, Brian W.; Radley, Ian

2017-03-01

PURPOSE Pixelated CdZnTe (CZT) detector arrays are used in molecular imaging applications that can enable precision medicine, including small-animal SPECT, cardiac SPECT, molecular breast imaging (MBI), and general purpose SPECT. The interplay of gamma camera, collimator, gantry motion, and image reconstruction determines image quality and dose-time-FOV tradeoffs. Both dose and exam time can be minimized without compromising diagnostic content. METHODS Integration of pixelated CZT detectors with advanced ASICs and readout electronics improves system performance. Because historically CZT was expensive, the first clinical applications were limited to small FOV. Radiation doses were initially high and exam times long. Advances have significantly improved efficiency of CZT-based molecular imaging systems and the cost has steadily declined. We have built a general purpose SPECT system using our 40 cm x 53 cm CZT gamma camera with 2 mm pixel pitch and characterized system performance. RESULTS Compared to NaI scintillator gamma cameras: intrinsic spatial resolution improved from 3.8 mm to 2.0 mm; energy resolution improved from 9.8% to <4 % at 140 keV; maximum count rate is <1.5 times higher; non-detection camera edges are reduced 3-fold. Scattered photons are greatly reduced in the photopeak energy window; image contrast is improved; and the optimal FOV is increased to the entire camera area. CONCLUSION Continual improvements in CZT detector arrays for molecular imaging, coupled with optimal collimator and image reconstruction, result in minimized dose and exam time. With CZT cost improving, affordable whole-body CZT general purpose SPECT is expected to enable precision medicine applications.

Development of an LYSO based gamma camera for positron and scinti-mammography

NASA Astrophysics Data System (ADS)

Liang, H.-C.; Jan, M.-L.; Lin, W.-C.; Yu, S.-F.; Su, J.-L.; Shen, L.-H.

2009-08-01

In this research, characteristics of combination of PSPMTs (position sensitive photo-multiplier tube) to form a larger detection area is studied. A home-made linear divider circuit was built for merging signals and readout. Borosilicate glasses were chosen for the scintillation light sharing in the crossover region. Deterioration effect caused by the light guide was understood. The influences of light guide and crossover region on the separable crystal size were evaluated. According to the test results, a gamma camera with a crystal block of 90 × 90 mm2 covered area, composed of 2 mm LYSO crystal pixels, was designed and fabricated. Measured performances showed that this camera worked fine in both 511 keV and lower energy gammas. The light loss behaviour within the crossover region was analyzed and realized. Through count rate measurements, the 176Lu nature background didn't show severe influence on the single photon imaging and exhibited an amount of less than 1/3 of all the events acquired. These results show that with using light sharing techniques, combination of multiple PSPMTs in both X and Y directions to build a large area imaging detector is capable to be achieved. Also this camera design is feasible to keep both the abilities for positron and single photon breast imaging applications. Separable crystal size is 2 mm with 2 mm thick glass applied for the light sharing in current status.

Photon detector configured to employ the Gunn effect and method of use

DOEpatents

Cich, Michael J

2015-03-17

Embodiments disclosed herein relate to photon detectors configured to employ the Gunn effect for detecting high-energy photons (e.g., x-rays and gamma rays) and methods of use. In an embodiment, a photon detector for detecting high-energy photons is disclosed. The photon detector includes a p-i-n semiconductor diode having a p-type semiconductor region, an n-type semiconductor region, and a compensated i-region disposed between the p-type semiconductor region and the n-type semiconductor region. The compensated i-region and has a width of about 100 .mu.m to about 400 .mu.m and is configured to exhibit the Gunn effect when the p-i-n semiconductor diode is forward biased a sufficient amount. The compensated i-region is doped to include a free carrier concentration of less than about 10.sup.10 cm.sup.-3.

Measuring the activity of a {sup 51}Cr neutrino source based on the gamma-radiation spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorbachev, V. V., E-mail: vvgor-gfb1@mail.ru; Gavrin, V. N.; Ibragimova, T. V.

A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of {sup 51}Cr is presented.

Novel drift structures for silicon and compound semiconductor X-ray and gamma-ray detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patt, B.E.; Iwanczyk, J.S.

Recently developed silicon- and compound-semiconductor-based drift detector structures have produced excellent performance for charged particles, X-rays, and gamma rays and for low-signal visible light detection. The silicon drift detector (SDD) structures that the authors discuss relate to direct X-ray detectors and scintillation photon detectors coupled with scintillators for gamma rays. Recent designs include several novel features that ensure very low dark current and hence low noise. In addition, application of thin window technology ensures a very high quantum efficiency entrance window on the drift photodetector. The main features of the silicon drift structures for X rays and light detection aremore » very small anode capacitance independent of the overall detector size, low noise, and high throughput. To take advantage of the small detector capacitance, the first stage of the electronics needs to be integrated into the detector anode. In the gamma-ray application, factors other than electronic noise dominate, and there is no need to integrate the electronics into the anode. Thus, a different drift structure is needed in conjunction with a high-Z material. The main features in this case are large active detector volume and electron-only induced signal.« less

Broadband image sensor array based on graphene-CMOS integration

NASA Astrophysics Data System (ADS)

Goossens, Stijn; Navickaite, Gabriele; Monasterio, Carles; Gupta, Shuchi; Piqueras, Juan José; Pérez, Raúl; Burwell, Gregory; Nikitskiy, Ivan; Lasanta, Tania; Galán, Teresa; Puma, Eric; Centeno, Alba; Pesquera, Amaia; Zurutuza, Amaia; Konstantatos, Gerasimos; Koppens, Frank

2017-06-01

Integrated circuits based on complementary metal-oxide-semiconductors (CMOS) are at the heart of the technological revolution of the past 40 years, enabling compact and low-cost microelectronic circuits and imaging systems. However, the diversification of this platform into applications other than microcircuits and visible-light cameras has been impeded by the difficulty to combine semiconductors other than silicon with CMOS. Here, we report the monolithic integration of a CMOS integrated circuit with graphene, operating as a high-mobility phototransistor. We demonstrate a high-resolution, broadband image sensor and operate it as a digital camera that is sensitive to ultraviolet, visible and infrared light (300-2,000 nm). The demonstrated graphene-CMOS integration is pivotal for incorporating 2D materials into the next-generation microelectronics, sensor arrays, low-power integrated photonics and CMOS imaging systems covering visible, infrared and terahertz frequencies.

Tissue-equivalent TL sheet dosimetry system for X- and gamma-ray dose mapping.

PubMed

Nariyama, N; Konnai, A; Ohnishi, S; Odano, N; Yamaji, A; Ozasa, N; Ishikawa, Y

2006-01-01

To measure dose distribution for X- and gamma rays simply and accurately, a tissue-equivalent thermoluminescent (TL) sheet-type dosemeter and reader system were developed. The TL sheet is composed of LiF:Mg,Cu,P and ETFE polymer, and the thickness is 0.2 mm. For the TL reading, a square heating plate, 20 cm on each side, was developed, and the temperature distribution was measured with an infrared thermal imaging camera. As a result, linearity within 2% and the homogeneity within 3% were confirmed. The TL signal emitted is detected using a CCD camera and displayed as a spatial dose distribution. Irradiation using synchrotron radiation between 10 and 100 keV and (60)Co gamma rays showed that the TL sheet dosimetry system was promising for radiation dose mapping for various purposes.

Gamma radiation in ceramic capacitors: a study for space missions

NASA Astrophysics Data System (ADS)

dos Santos Ferreira, Eduardo; Sarango Souza, Juliana

2017-10-01

We studied the real time effects of the gamma radiation in ceramic capacitors, in order to evaluate the effects of cosmic radiation on these devices. Space missions have electronic circuits with various types of devices, many studies have been done on semiconductor devices exposed to gamma radiation, but almost no studies for passive components, in particular ceramic capacitors. Commercially sold ceramic capacitors were exposed to gamma radiation, and the capacitance was measured before and after exposure. The results clearly show that the capacitance decreases with exposure to gamma radiation. We confirmed this observation in a real time capacitance measurement, obtained using a data logging system developed by us using the open source Arduino platform.

SU-F-J-200: An Improved Method for Event Selection in Compton Camera Imaging for Particle Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackin, D; Beddar, S; Polf, J

2016-06-15

Purpose: The uncertainty in the beam range in particle therapy limits the conformality of the dose distributions. Compton scatter cameras (CC), which measure the prompt gamma rays produced by nuclear interactions in the patient tissue, can reduce this uncertainty by producing 3D images confirming the particle beam range and dose delivery. However, the high intensity and short time windows of the particle beams limit the number of gammas detected. We attempt to address this problem by developing a method for filtering gamma ray scattering events from the background by applying the known gamma ray spectrum. Methods: We used a 4more » stage Compton camera to record in list mode the energy deposition and scatter positions of gammas from a Co-60 source. Each CC stage contained a 4×4 array of CdZnTe crystal. To produce images, we used a back-projection algorithm and four filtering Methods: basic, energy windowing, delta energy (ΔE), or delta scattering angle (Δθ). Basic filtering requires events to be physically consistent. Energy windowing requires event energy to fall within a defined range. ΔE filtering selects events with the minimum difference between the measured and a known gamma energy (1.17 and 1.33 MeV for Co-60). Δθ filtering selects events with the minimum difference between the measured scattering angle and the angle corresponding to a known gamma energy. Results: Energy window filtering reduced the FWHM from 197.8 mm for basic filtering to 78.3 mm. ΔE and Δθ filtering achieved the best results, FWHMs of 64.3 and 55.6 mm, respectively. In general, Δθ filtering selected events with scattering angles < 40°, while ΔE filtering selected events with angles > 60°. Conclusion: Filtering CC events improved the quality and resolution of the corresponding images. ΔE and Δθ filtering produced similar results but each favored different events.« less

ProxiScan™: A Novel Camera for Imaging Prostate Cancer

ScienceCinema

Ralph James

2017-12-09

ProxiScan is a compact gamma camera suited for high-resolution imaging of prostate cancer. Developed by Brookhaven National Laboratory and Hybridyne Imaging Technologies, Inc., ProxiScan won a 2009 R&D 100 Award, sponsored by R&D Magazine to recognize t

High speed photography, videography, and photonics III; Proceedings of the Meeting, San Diego, CA, August 22, 23, 1985

NASA Technical Reports Server (NTRS)

Ponseggi, B. G. (Editor); Johnson, H. C. (Editor)

1985-01-01

Papers are presented on the picosecond electronic framing camera, photogrammetric techniques using high-speed cineradiography, picosecond semiconductor lasers for characterizing high-speed image shutters, the measurement of dynamic strain by high-speed moire photography, the fast framing camera with independent frame adjustments, design considerations for a data recording system, and nanosecond optical shutters. Consideration is given to boundary-layer transition detectors, holographic imaging, laser holographic interferometry in wind tunnels, heterodyne holographic interferometry, a multispectral video imaging and analysis system, a gated intensified camera, a charge-injection-device profile camera, a gated silicon-intensified-target streak tube and nanosecond-gated photoemissive shutter tubes. Topics discussed include high time-space resolved photography of lasers, time-resolved X-ray spectrographic instrumentation for laser studies, a time-resolving X-ray spectrometer, a femtosecond streak camera, streak tubes and cameras, and a short pulse X-ray diagnostic development facility.

Development of Camera Electronics for the Advanced Gamma-ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Tajima, Hiroyasu

2009-05-01

AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. We have developed test systems for some of these concepts and are testing their performance. Here we present test results of the test systems.

The gamma-ray Cherenkov telescope for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Tibaldo, L.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Franco, A.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jankowsky, D.; Jegouzo, I.; Jogler, T.; Kraus, M.; Lapington, J. S.; Laporte, P.; Lefaucheur, J.; Markoff, S.; Melse, T.; Mohrmann, L.; Molyneux, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Trichard, C.; Vink, J.; Watson, J. J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

2017-01-01

The Cherenkov Telescope Array (CTA) is a forthcoming ground-based observatory for very-high-energy gamma rays. CTA will consist of two arrays of imaging atmospheric Cherenkov telescopes in the Northern and Southern hemispheres, and will combine telescopes of different types to achieve unprecedented performance and energy coverage. The Gamma-ray Cherenkov Telescope (GCT) is one of the small-sized telescopes proposed for CTA to explore the energy range from a few TeV to hundreds of TeV with a field of view ≳ 8° and angular resolution of a few arcminutes. The GCT design features dual-mirror Schwarzschild-Couder optics and a compact camera based on densely-pixelated photodetectors as well as custom electronics. In this contribution we provide an overview of the GCT project with focus on prototype development and testing that is currently ongoing. We present results obtained during the first on-telescope campaign in late 2015 at the Observatoire de Paris-Meudon, during which we recorded the first Cherenkov images from atmospheric showers with the GCT multi-anode photomultiplier camera prototype. We also discuss the development of a second GCT camera prototype with silicon photomultipliers as photosensors, and plans toward a contribution to the realisation of CTA.

Improved neutron-gamma discrimination for a {sup 6}Li-glass neutron detector using digital signal analysis methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, C. L., E-mail: wangc@ornl.gov; Riedel, R. A.

2016-01-15

A {sup 6}Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10{sup 4}. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a{sub 1}, b{submore » 0}) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods.« less

Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics

PubMed Central

Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D.; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

2017-01-01

Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that “Electron Tracking Compton Camera” (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics. PMID:28155870

Visible scintillation photodetector device incorporating chalcopyrite semiconductor crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stowe, Ashley C.; Burger, Arnold

2017-04-04

A photodetector device, including: a scintillator material operable for receiving incident radiation and emitting photons in response; a photodetector material coupled to the scintillator material operable for receiving the photons emitted by the scintillator material and generating a current in response, wherein the photodetector material includes a chalcopyrite semiconductor crystal; and a circuit coupled to the photodetector material operable for characterizing the incident radiation based on the current generated by the photodetector material. Optionally, the scintillator material includes a gamma scintillator material and the incident radiation received includes gamma rays. Optionally, the photodetector material is further operable for receiving thermalmore » neutrons and generating a current in response. The circuit is further operable for characterizing the thermal neutrons based on the current generated by the photodetector material.« less

Camera-on-a-Chip

NASA Technical Reports Server (NTRS)

1999-01-01

Jet Propulsion Laboratory's research on a second generation, solid-state image sensor technology has resulted in the Complementary Metal- Oxide Semiconductor Active Pixel Sensor (CMOS), establishing an alternative to the Charged Coupled Device (CCD). Photobit Corporation, the leading supplier of CMOS image sensors, has commercialized two products of their own based on this technology: the PB-100 and PB-300. These devices are cameras on a chip, combining all camera functions. CMOS "active-pixel" digital image sensors offer several advantages over CCDs, a technology used in video and still-camera applications for 30 years. The CMOS sensors draw less energy, they use the same manufacturing platform as most microprocessors and memory chips, and they allow on-chip programming of frame size, exposure, and other parameters.

Ultraviolet Imaging with Low Cost Smartphone Sensors: Development and Application of a Raspberry Pi-Based UV Camera.

PubMed

Wilkes, Thomas C; McGonigle, Andrew J S; Pering, Tom D; Taggart, Angus J; White, Benjamin S; Bryant, Robert G; Willmott, Jon R

2016-10-06

Here, we report, for what we believe to be the first time, on the modification of a low cost sensor, designed for the smartphone camera market, to develop an ultraviolet (UV) camera system. This was achieved via adaptation of Raspberry Pi cameras, which are based on back-illuminated complementary metal-oxide semiconductor (CMOS) sensors, and we demonstrated the utility of these devices for applications at wavelengths as low as 310 nm, by remotely sensing power station smokestack emissions in this spectral region. Given the very low cost of these units, ≈ USD 25, they are suitable for widespread proliferation in a variety of UV imaging applications, e.g., in atmospheric science, volcanology, forensics and surface smoothness measurements.

An Acoustic Charge Transport Imager for High Definition Television

NASA Technical Reports Server (NTRS)

Hunt, William D.; Brennan, Kevin; May, Gary; Glenn, William E.; Richardson, Mike; Solomon, Richard

1999-01-01

This project, over its term, included funding to a variety of companies and organizations. In addition to Georgia Tech these included Florida Atlantic University with Dr. William E. Glenn as the P.I., Kodak with Mr. Mike Richardson as the P.I. and M.I.T./Polaroid with Dr. Richard Solomon as the P.I. The focus of the work conducted by these organizations was the development of camera hardware for High Definition Television (HDTV). The focus of the research at Georgia Tech was the development of new semiconductor technology to achieve a next generation solid state imager chip that would operate at a high frame rate (I 70 frames per second), operate at low light levels (via the use of avalanche photodiodes as the detector element) and contain 2 million pixels. The actual cost required to create this new semiconductor technology was probably at least 5 or 6 times the investment made under this program and hence we fell short of achieving this rather grand goal. We did, however, produce a number of spin-off technologies as a result of our efforts. These include, among others, improved avalanche photodiode structures, significant advancement of the state of understanding of ZnO/GaAs structures and significant contributions to the analysis of general GaAs semiconductor devices and the design of Surface Acoustic Wave resonator filters for wireless communication. More of these will be described in the report. The work conducted at the partner sites resulted in the development of 4 prototype HDTV cameras. The HDTV camera developed by Kodak uses the Kodak KAI-2091M high- definition monochrome image sensor. This progressively-scanned charge-coupled device (CCD) can operate at video frame rates and has 9 gm square pixels. The photosensitive area has a 16:9 aspect ratio and is consistent with the "Common Image Format" (CIF). It features an active image area of 1928 horizontal by 1084 vertical pixels and has a 55% fill factor. The camera is designed to operate in continuous mode with an output data rate of 5MHz, which gives a maximum frame rate of 4 frames per second. The MIT/Polaroid group developed two cameras under this program. The cameras have effectively four times the current video spatial resolution and at 60 frames per second are double the normal video frame rate.

Renal Scintigraphy

MedlinePlus

... in your hand or arm. When it is time for the imaging to begin, the gamma camera will take a series of images. The camera may rotate around you or it may stay in one position and you will be asked to change positions in ... to remain still for brief periods of time. You may be asked to sit or lie ...

Molecular Imaging in the College of Optical Sciences – An Overview of Two Decades of Instrumentation Development

PubMed Central

Furenlid, Lars R.; Barrett, Harrison H.; Barber, H. Bradford; Clarkson, Eric W.; Kupinski, Matthew A.; Liu, Zhonglin; Stevenson, Gail D.; Woolfenden, James M.

2015-01-01

During the past two decades, researchers at the University of Arizona’s Center for Gamma-Ray Imaging (CGRI) have explored a variety of approaches to gamma-ray detection, including scintillation cameras, solid-state detectors, and hybrids such as the intensified Quantum Imaging Device (iQID) configuration where a scintillator is followed by optical gain and a fast CCD or CMOS camera. We have combined these detectors with a variety of collimation schemes, including single and multiple pinholes, parallel-hole collimators, synthetic apertures, and anamorphic crossed slits, to build a large number of preclinical molecular-imaging systems that perform Single-Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET), and X-Ray Computed Tomography (CT). In this paper, we discuss the themes and methods we have developed over the years to record and fully use the information content carried by every detected gamma-ray photon. PMID:26236069

MONICA: A Compact, Portable Dual Gamma Camera System for Mouse Whole-Body Imaging

PubMed Central

Xi, Wenze; Seidel, Jurgen; Karkareka, John W.; Pohida, Thomas J.; Milenic, Diane E.; Proffitt, James; Majewski, Stan; Weisenberger, Andrew G.; Green, Michael V.; Choyke, Peter L.

2009-01-01

Introduction We describe a compact, portable dual-gamma camera system (named “MONICA” for MObile Nuclear Imaging CAmeras) for visualizing and analyzing the whole-body biodistribution of putative diagnostic and therapeutic single photon emitting radiotracers in animals the size of mice. Methods Two identical, miniature pixelated NaI(Tl) gamma cameras were fabricated and installed “looking up” through the tabletop of a compact portable cart. Mice are placed directly on the tabletop for imaging. Camera imaging performance was evaluated with phantoms and field performance was evaluated in a weeklong In-111 imaging study performed in a mouse tumor xenograft model. Results Tc-99m performance measurements, using a photopeak energy window of 140 keV ± 10%, yielded the following results: spatial resolution (FWHM at 1-cm), 2.2-mm; sensitivity, 149 cps/MBq (5.5 cps/μCi); energy resolution (FWHM), 10.8%; count rate linearity (count rate vs. activity), r2 = 0.99 for 0–185 MBq (0–5 mCi) in the field-of-view (FOV); spatial uniformity, < 3% count rate variation across the FOV. Tumor and whole-body distributions of the In-111 agent were well visualized in all animals in 5-minute images acquired throughout the 168-hour study period. Conclusion Performance measurements indicate that MONICA is well suited to whole-body single photon mouse imaging. The field study suggests that inter-device communications and user-oriented interfaces included in the MONICA design facilitate use of the system in practice. We believe that MONICA may be particularly useful early in the (cancer) drug development cycle where basic whole-body biodistribution data can direct future development of the agent under study and where logistical factors, e.g. limited imaging space, portability, and, potentially, cost are important. PMID:20346864

Inspection and Gamma-Ray Dose Rate Measurements of the Annulus of the VSC-17 Concrete Spent Nuclear Fuel Storage Cask

DOE Office of Scientific and Technical Information (OSTI.GOV)

P. L. Winston

2007-09-01

The air cooling annulus of the Ventilated Storage Cask (VSC)-17 spent fuel storage cask was inspected using a Toshiba 7 mm (1/4”) CCD video camera. The dose rates observed in the annular space were measured to provide a reference for the activity to which the camera(s) being tested were being exposed. No gross degradation, pitting, or general corrosion was observed.

High-Resolution Scintimammography: A Pilot Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rachel F. Brem; Joelle M. Schoonjans; Douglas A. Kieper

2002-07-01

This study evaluated a novel high-resolution breast-specific gamma camera (HRBGC) for the detection of suggestive breast lesions. Methods: Fifty patients (with 58 breast lesions) for whom a scintimammogram was clinically indicated were prospectively evaluated with a general-purpose gamma camera and a novel HRBGC prototype. The results of conventional and high-resolution nuclear studies were prospectively classified as negative (normal or benign) or positive (suggestive or malignant) by 2 radiologists who were unaware of the mammographic and histologic results. All of the included lesions were confirmed by pathology. Results: There were 30 benign and 28 malignant lesions. The sensitivity for detection ofmore » breast cancer was 64.3% (18/28) with the conventional camera and 78.6% (22/28) with the HRBGC. The specificity with both systems was 93.3% (28/30). For the 18 nonpalpable lesions, sensitivity was 55.5% (10/18) and 72.2% (13/18) with the general-purpose camera and the HRBGC, respectively. For lesions 1 cm, 7 of 15 were detected with the general-purpose camera and 10 of 15 with the HRBGC. Four lesions (median size, 8.5 mm) were detected only with the HRBGC and were missed by the conventional camera. Conclusion: Evaluation of indeterminate breast lesions with an HRBGC results in improved sensitivity for the detection of cancer, with greater improvement shown for nonpalpable and 1-cm lesions.« less

Temporal Imaging CeBr3 Compton Camera: A New Concept for Nuclear Decommissioning and Nuclear Waste Management

NASA Astrophysics Data System (ADS)

Iltis, A.; Snoussi, H.; Magalhaes, L. Rodrigues de; Hmissi, M. Z.; Zafiarifety, C. Tata; Tadonkeng, G. Zeufack; Morel, C.

2018-01-01

During nuclear decommissioning or waste management operations, a camera that could make an image of the contamination field and identify and quantify the contaminants would be a great progress. Compton cameras have been proposed, but their limited efficiency for high energy gamma rays and their cost have severely limited their application. Our objective is to promote a Compton camera for the energy range (200 keV - 2 MeV) that uses fast scintillating crystals and a new concept for locating scintillation event: Temporal Imaging. Temporal Imaging uses monolithic plates of fast scintillators and measures photons time of arrival distribution in order to locate each gamma ray with a high precision in space (X,Y,Z), time (T) and energy (E). This provides a native estimation of the depth of interaction (Z) of every detected gamma ray. This also allows a time correction for the propagation time of scintillation photons inside the crystal, therefore resulting in excellent time resolution. The high temporal resolution of the system makes it possible to veto quite efficiently background by using narrow time coincidence (< 300 ps). It is also possible to reconstruct the direction of propagation of the photons inside the detector using timing constraints. The sensitivity of our system is better than 1 nSv/h in a 60 s acquisition with a 22Na source. The project TEMPORAL is funded by the ANDRA/PAI under the grant No. RTSCNADAA160019.

Design of Dual-Road Transportable Portal Monitoring System for Visible Light and Gamma-Ray Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karnowski, Thomas Paul; Cunningham, Mark F; Goddard Jr, James Samuel

2010-01-01

The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they entermore » and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third alignment camera for motion compensation and are mounted on a 50 deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.« less

Design of dual-road transportable portal monitoring system for visible light and gamma-ray imaging

NASA Astrophysics Data System (ADS)

Karnowski, Thomas P.; Cunningham, Mark F.; Goddard, James S.; Cheriyadat, Anil M.; Hornback, Donald E.; Fabris, Lorenzo; Kerekes, Ryan A.; Ziock, Klaus-Peter; Bradley, E. Craig; Chesser, J.; Marchant, W.

2010-04-01

The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they enter and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third "alignment" camera for motion compensation and are mounted on a 50' deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.

Video approach to chemiluminescence detection using a low-cost complementary metal oxide semiconductor (CMOS)-based camera: determination of paracetamol in pharmaceutical formulations.

PubMed

Lahuerta-Zamora, Luis; Mellado-Romero, Ana M

2017-06-01

A new system for continuous flow chemiluminescence detection, based on the use of a simple and low-priced lens-free digital camera (with complementary metal oxide semiconductor technology) as a detector, is proposed for the quantitative determination of paracetamol in commercial pharmaceutical formulations. Through the camera software, AVI video files of the chemiluminescence emission are captured and then, using friendly ImageJ public domain software (from National Institutes for Health), properly processed in order to extract the analytical information. The calibration graph was found to be linear over the range 0.01-0.10 mg L -1 and over the range 1.0-100.0 mg L -1 of paracetamol, the limit of detection being 10 μg L -1 . No significative interferences were found. Paracetamol was determined in three different pharmaceutical formulations: Termalgin®, Efferalgan® and Gelocatil®. The obtained results compared well with those declared on the formulation label and with those obtained through the official analytical method of British Pharmacopoeia. Graphical abstract Abbreviated scheme of the new chemiluminescence detection system proposed in this paper.

Novel Chalcogenide Materials for X-ray and Gamma-ray Detection

DTIC Science & Technology

2016-05-01

53 Novel Chalcogenide Materials for x-ray and y-ray Detection Distribution Statement A. Approved for public release; distribution is unlimited. 0...TITLE AND SUBTITLE Sa. CONTRACT NUMBER Novel Chalcogenide Materials for x-ray and y-ray Detection Sb. GRANT NUMBER HDTRA 1-09-1-0044 Sc. PROGRAM...heavy atom chalcogenide family of semiconductors for room temperature gamma radiation detection . Its goal was to accelerate nuclear detector material

Advances in TlBr detector development

NASA Astrophysics Data System (ADS)

Hitomi, Keitaro; Shoji, Tadayoshi; Ishii, Keizo

2013-09-01

Thallium bromide (TlBr) is a promising compound semiconductor for fabrication of gamma-ray detectors. The attractive physical properties of TlBr lie in its high photon stopping power, high resistivity and good charge transport properties. Gamma-ray detectors fabricated from TlBr crystals have exhibited excellent spectroscopic performance. In this paper, advances in TlBr radiation detector development are reviewed with emphasis on crystal growth, detector fabrication, physical properties and detector performance.

High resolution bone mineral densitometry with a gamma camera

NASA Technical Reports Server (NTRS)

Leblanc, A.; Evans, H.; Jhingran, S.; Johnson, P.

1983-01-01

A technique by which the regional distribution of bone mineral can be determined in bone samples from small animals is described. The technique employs an Anger camera interfaced to a medical computer. High resolution imaging is possible by producing magnified images of the bone samples. Regional densitometry of femurs from oophorectomised and bone mineral loss.

Real-time proton beam range monitoring by means of prompt-gamma detection with a collimated camera

NASA Astrophysics Data System (ADS)

Roellinghoff, F.; Benilov, A.; Dauvergne, D.; Dedes, G.; Freud, N.; Janssens, G.; Krimmer, J.; Létang, J. M.; Pinto, M.; Prieels, D.; Ray, C.; Smeets, J.; Stichelbaut, F.; Testa, E.

2014-03-01

Prompt-gamma profile was measured at WPE-Essen using 160 MeV protons impinging a movable PMMA target. A single collimated detector was used with time-of-flight (TOF) to reduce the background due to neutrons. The target entrance rise and the Bragg peak falloff retrieval precision was determined as a function of incident proton number by a fitting procedure using independent data sets. Assuming improved sensitivity of this camera design by using a greater number of detectors, retrieval precisions of 1 to 2 mm (rms) are expected for a clinical pencil beam. TOF improves the contrast-to-noise ratio and the performance of the method significantly.

GCT, the Gamma-ray Cherenkov Telescope for multi-TeV science with the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Sol, H.; Dournaux, J.-L.; Laporte, P.

2016-12-01

GCT is a gamma-ray telescope proposed for the high-energy section of the Cherenkov Telescope Array (CTA). A GCT prototype telescope has been designed, built and installed at the Observatoire de Paris in Meudon. Equipped with the first GCT prototype camera developed by an international collaboration, the complete GCT prototype was inaugurated in December 2015, after getting its first Cherenkov light on the night sky in November. The phase of tests, assessment, and optimisation is now coming to an end. Pre-production of the first GCT telescopes and cameras should start in 2017, for an installation on the Chilean site of CTA in 2018.

Non-flickering 100 m RGB visible light communication transmission based on a CMOS image sensor.

PubMed

Chow, Chi-Wai; Shiu, Ruei-Jie; Liu, Yen-Chun; Liu, Yang; Yeh, Chien-Hung

2018-03-19

We demonstrate a non-flickering 100 m long-distance RGB visible light communication (VLC) transmission based on a complementary-metal-oxide-semiconductor (CMOS) camera. Experimental bit-error rate (BER) measurements under different camera ISO values and different transmission distances are evaluated. Here, we also experimentally reveal that the rolling shutter effect- (RSE) based VLC system cannot work at long distance transmission, and the under-sampled modulation- (USM) based VLC system is a good choice.

Wafer-fused semiconductor radiation detector

DOEpatents

Lee, Edwin Y.; James, Ralph B.

2002-01-01

Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

Ultraviolet Imaging with Low Cost Smartphone Sensors: Development and Application of a Raspberry Pi-Based UV Camera

PubMed Central

Wilkes, Thomas C.; McGonigle, Andrew J. S.; Pering, Tom D.; Taggart, Angus J.; White, Benjamin S.; Bryant, Robert G.; Willmott, Jon R.

2016-01-01

Here, we report, for what we believe to be the first time, on the modification of a low cost sensor, designed for the smartphone camera market, to develop an ultraviolet (UV) camera system. This was achieved via adaptation of Raspberry Pi cameras, which are based on back-illuminated complementary metal-oxide semiconductor (CMOS) sensors, and we demonstrated the utility of these devices for applications at wavelengths as low as 310 nm, by remotely sensing power station smokestack emissions in this spectral region. Given the very low cost of these units, ≈ USD 25, they are suitable for widespread proliferation in a variety of UV imaging applications, e.g., in atmospheric science, volcanology, forensics and surface smoothness measurements. PMID:27782054

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

NASA Astrophysics Data System (ADS)

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

2000-07-01

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

Coincidence ion imaging with a fast frame camera

NASA Astrophysics Data System (ADS)

Lee, Suk Kyoung; Cudry, Fadia; Lin, Yun Fei; Lingenfelter, Steven; Winney, Alexander H.; Fan, Lin; Li, Wen

2014-12-01

A new time- and position-sensitive particle detection system based on a fast frame CMOS (complementary metal-oxide semiconductors) camera is developed for coincidence ion imaging. The system is composed of four major components: a conventional microchannel plate/phosphor screen ion imager, a fast frame CMOS camera, a single anode photomultiplier tube (PMT), and a high-speed digitizer. The system collects the positional information of ions from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of a PMT processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum of a PMT. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide.

Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera

PubMed Central

Feng, Wei; Zhang, Fumin; Qu, Xinghua; Zheng, Shiwei

2016-01-01

High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD) camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second) gain in temporal resolution by using a 25 fps camera. PMID:26959023

Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera.

PubMed

Feng, Wei; Zhang, Fumin; Qu, Xinghua; Zheng, Shiwei

2016-03-04

High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD) camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second) gain in temporal resolution by using a 25 fps camera.

Lensless imaging for wide field of view

NASA Astrophysics Data System (ADS)

Nagahara, Hajime; Yagi, Yasushi

2015-02-01

It is desirable to engineer a small camera with a wide field of view (FOV) because of current developments in the field of wearable cameras and computing products, such as action cameras and Google Glass. However, typical approaches for achieving wide FOV, such as attaching a fisheye lens and convex mirrors, require a trade-off between optics size and the FOV. We propose camera optics that achieve a wide FOV, and are at the same time small and lightweight. The proposed optics are a completely lensless and catoptric design. They contain four mirrors, two for wide viewing, and two for focusing the image on the camera sensor. The proposed optics are simple and can be simply miniaturized, since we use only mirrors for the proposed optics and the optics are not susceptible to chromatic aberration. We have implemented the prototype optics of our lensless concept. We have attached the optics to commercial charge-coupled device/complementary metal oxide semiconductor cameras and conducted experiments to evaluate the feasibility of our proposed optics.

Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

DOE PAGES

Wang, Cai -Lin; Riedel, Richard A.

2016-01-14

A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at SNS. Traditional pulse-height analysis (PHA) for neutron-gamma discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10 4. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, five digital signal analysis methods of individual waveforms from PMTs were proposed using: i). pulse-amplitude histogram; ii). power spectrum analysis combined with the maximum pulse amplitude; iii). two event parameters (a 1, b 0) obtained from Wiener filter; iv). anmore » effective amplitude (m) obtained from an adaptive least-mean-square (LMS) filter; and v). a cross-correlation (CC) coefficient between an individual waveform and a reference. The NGD ratios can be 1-102 times those from traditional PHA method. A brighter scintillator GS2 has better NGD ratio than GS20, but lower neutron detection efficiency. The ultimate NGD ratio is related to the ambient, high-energy background events. Moreover, our results indicate the NGD capability of neutron Anger cameras can be improved using digital signal analysis methods and brighter neutron scintillators.« less

Code CUGEL: A code to unfold Ge(Li) spectrometer polyenergetic gamma photon experimental distributions

NASA Technical Reports Server (NTRS)

Steyn, J. J.; Born, U.

1970-01-01

A FORTRAN code was developed for the Univac 1108 digital computer to unfold lithium-drifted germanium semiconductor spectrometers, polyenergetic gamma photon experimental distributions. It was designed to analyze the combination continuous and monoenergetic gamma radiation field of radioisotope volumetric sources. The code generates the detector system response matrix function and applies it to monoenergetic spectral components discretely and to the continuum iteratively. It corrects for system drift, source decay, background, and detection efficiency. Results are presented in digital form for differential and integrated photon number and energy distributions, and for exposure dose.

SU-C-201-03: Coded Aperture Gamma-Ray Imaging Using Pixelated Semiconductor Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, S; Kaye, W; Jaworski, J

2015-06-15

Purpose: Improved localization of gamma-ray emissions from radiotracers is essential to the progress of nuclear medicine. Polaris is a portable, room-temperature operated gamma-ray imaging spectrometer composed of two 3×3 arrays of thick CdZnTe (CZT) detectors, which detect gammas between 30keV and 3MeV with energy resolution of <1% FWHM at 662keV. Compton imaging is used to map out source distributions in 4-pi space; however, is only effective above 300keV where Compton scatter is dominant. This work extends imaging to photoelectric energies (<300keV) using coded aperture imaging (CAI), which is essential for localization of Tc-99m (140keV). Methods: CAI, similar to the pinholemore » camera, relies on an attenuating mask, with open/closed elements, placed between the source and position-sensitive detectors. Partial attenuation of the source results in a “shadow” or count distribution that closely matches a portion of the mask pattern. Ideally, each source direction corresponds to a unique count distribution. Using backprojection reconstruction, the source direction is determined within the field of view. The knowledge of 3D position of interaction results in improved image quality. Results: Using a single array of detectors, a coded aperture mask, and multiple Co-57 (122keV) point sources, image reconstruction is performed in real-time, on an event-by-event basis, resulting in images with an angular resolution of ∼6 degrees. Although material nonuniformities contribute to image degradation, the superposition of images from individual detectors results in improved SNR. CAI was integrated with Compton imaging for a seamless transition between energy regimes. Conclusion: For the first time, CAI has been applied to thick, 3D position sensitive CZT detectors. Real-time, combined CAI and Compton imaging is performed using two 3×3 detector arrays, resulting in a source distribution in space. This system has been commercialized by H3D, Inc. and is being acquired for various applications worldwide, including proton therapy imaging R&D.« less

The upgrade of the H.E.S.S. cameras

NASA Astrophysics Data System (ADS)

Giavitto, Gianluca; Ashton, Terry; Balzer, Arnim; Berge, David; Brun, Francois; Chaminade, Thomas; Delagnes, Eric; Fontaine, Gerard; Füßling, Matthias; Giebels, Berrie; Glicenstein, Jean-Francois; Gräber, Tobias; Hinton, Jim; Jahnke, Albert; Klepser, Stefan; Kossatz, Marko; Kretzschmann, Axel; Lefranc, Valentin; Leich, Holger; Lüdecke, Hartmut; Lypova, Iryna; Manigot, Pascal; Marandon, Vincent; Moulin, Emmanuel; Naurois, Mathieu de; Nayman, Patrick; Ohm, Stefan; Penno, Marek; Ross, Duncan; Salek, David; Schade, Markus; Schwab, Thomas; Simoni, Rachel; Stegmann, Christian; Steppa, Constantin; Thornhill, Julian; Toussnel, Francois

2017-12-01

The High Energy Stereoscopic System (HESS) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in the Khomas highland in Namibia. It was built to detect Very High Energy (VHE > 100 GeV) cosmic gamma rays. Since 2003, HESS has discovered the majority of the known astrophysical VHE gamma-ray sources, opening a new observational window on the extreme non-thermal processes at work in our universe. HESS consists of four 12-m diameter Cherenkov telescopes (CT1-4), which started data taking in 2002, and a larger 28-m telescope (CT5), built in 2012, which lowers the energy threshold of the array to 30 GeV . The cameras of CT1-4 are currently undergoing an extensive upgrade, with the goals of reducing their failure rate, reducing their readout dead time and improving the overall performance of the array. The entire camera electronics has been renewed from ground-up, as well as the power, ventilation and pneumatics systems, and the control and data acquisition software. Only the PMTs and their HV supplies have been kept from the original cameras. Novel technical solutions have been introduced, which will find their way into some of the Cherenkov cameras foreseen for the next-generation Cherenkov Telescope Array (CTA) observatory. In particular, the camera readout system is the first large-scale system based on the analog memory chip NECTAr, which was designed for CTA cameras. The camera control subsystems and the control software framework also pursue an innovative design, exploiting cutting-edge hardware and software solutions which excel in performance, robustness and flexibility. The CT1 camera has been upgraded in July 2015 and is currently taking data; CT2-4 have been upgraded in fall 2016. Together they will assure continuous operation of HESS at its full sensitivity until and possibly beyond the advent of CTA. This contribution describes the design, the testing and the in-lab and on-site performance of all components of the newly upgraded HESS camera.

The GCT camera for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Lapington, J. S.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Bose, R.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Buckley, J.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Franco, A.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jankowsky, D.; Jegouzo, I.; Jogler, T.; Kawashima, T.; Kraus, M.; Laporte, P.; Leach, S.; Lefaucheur, J.; Markoff, S.; Melse, T.; Minaya, I. A.; Mohrmann, L.; Molyneux, P.; Moore, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayede, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Varner, G.; Vink, J.; Watson, J. J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

2017-12-01

The Gamma Cherenkov Telescope (GCT) is one of the designs proposed for the Small Sized Telescope (SST) section of the Cherenkov Telescope Array (CTA). The GCT uses dual-mirror optics, resulting in a compact telescope with good image quality and a large field of view with a smaller, more economical, camera than is achievable with conventional single mirror solutions. The photon counting GCT camera is designed to record the flashes of atmospheric Cherenkov light from gamma and cosmic ray initiated cascades, which last only a few tens of nanoseconds. The GCT optics require that the camera detectors follow a convex surface with a radius of curvature of 1 m and a diameter of 35 cm, which is approximated by tiling the focal plane with 32 modules. The first camera prototype is equipped with multi-anode photomultipliers, each comprising an 8×8 array of 6×6 mm2 pixels to provide the required angular scale, adding up to 2048 pixels in total. Detector signals are shaped, amplified and digitised by electronics based on custom ASICs that provide digitisation at 1 GSample/s. The camera is self-triggering, retaining images where the focal plane light distribution matches predefined spatial and temporal criteria. The electronics are housed in the liquid-cooled, sealed camera enclosure. LED flashers at the corners of the focal plane provide a calibration source via reflection from the secondary mirror. The first GCT camera prototype underwent preliminary laboratory tests last year. In November 2015, the camera was installed on a prototype GCT telescope (SST-GATE) in Paris and was used to successfully record the first Cherenkov light of any CTA prototype, and the first Cherenkov light seen with such a dual-mirror optical system. A second full-camera prototype based on Silicon Photomultipliers is under construction. Up to 35 GCTs are envisaged for CTA.

SU-F-J-182: Investigation of Systems for Improved Accuracy in Clinical Y-90 Percent Delivered Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

McBeth, R; Elder, D; Kesner, A

2016-06-15

Purpose: Y-90 Selective Internal Radiation Therapy (SIRT) is used to treat liver tumors, and by nature has variability in the percent of the intended dose that is actually delivered. To determine the quality of the administration, pre and post activity measurements are taken, and used to infer percent delivered. Vendor specifications indicate the use of an ion chamber to take these measurements. In our work, we investigated the accuracy of ion chambers, and compared them to other detector systems. Methods: We have built phantoms, phantom holders, and protocols, which allow us to measure our Y90 doses with varying apparatuses: amore » dose calibrator, a Geiger-counter, an ion chamber, a crystal based thyroid probe, and a gamma camera. We have set up a system that has enabled us to gather data by measuring clinical Y90 doses as they are used in the clinic using all of the instrumental methods. Five initial doses (25 measurements/acquisitions) have been taken at the time of this abstract submission. Results: Our initial results show that measurements acquired using scintillation based detectors (thyroid probe and gamma camera) correlate better with the gold standard (i.e. the dose calibrator). Pearson correlations between the dose calibrator measurements and the GM counter, Ion chamber, thyroid probe, and gamma camera were found to be 0.88, 0.83, 0.98, 0.99, respectively. More acquisitions and analysis are planned to determine the precision of the systems, as well as optimal energy window settings. Conclusion: It is likely that current standard practice can be improved using scintillation crystal based detectors. Such systems are more sensitive, can integrate signal, and can use energy discrimination. Furthermore, phantoms can be built to integrate with probe and gamma camera systems that are robust and provide reproducibility. Future work will include expanded acquisition and analysis.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turkington, T.

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

TU-H-206-01: An Automated Approach for Identifying Geometric Distortions in Gamma Cameras

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mann, S; Nelson, J; Samei, E

2016-06-15

Purpose: To develop a clinically-deployable, automated process for detecting artifacts in routine nuclear medicine (NM) quality assurance (QA) bar phantom images. Methods: An artifact detection algorithm was created to analyze bar phantom images as part of an ongoing QA program. A low noise, high resolution reference image was acquired from an x-ray of the bar phantom with a Philips Digital Diagnost system utilizing image stitching. NM bar images, acquired for 5 million counts over a 512×512 matrix, were registered to the template image by maximizing mutual information (MI). The MI index was used as an initial test for artifacts; lowmore » values indicate an overall presence of distortions regardless of their spatial location. Images with low MI scores were further analyzed for bar linearity, periodicity, alignment, and compression to locate differences with respect to the template. Findings from each test were spatially correlated and locations failing multiple tests were flagged as potential artifacts requiring additional visual analysis. The algorithm was initially deployed for GE Discovery 670 and Infinia Hawkeye gamma cameras. Results: The algorithm successfully identified clinically relevant artifacts from both systems previously unnoticed by technologists performing the QA. Average MI indices for artifact-free images are 0.55. Images with MI indices < 0.50 have shown 100% sensitivity and specificity for artifact detection when compared with a thorough visual analysis. Correlation of geometric tests confirms the ability to spatially locate the most likely image regions containing an artifact regardless of initial phantom orientation. Conclusion: The algorithm shows the potential to detect gamma camera artifacts that may be missed by routine technologist inspections. Detection and subsequent correction of artifacts ensures maximum image quality and may help to identify failing hardware before it impacts clinical workflow. Going forward, the algorithm is being deployed to monitor data from all gamma cameras within our health system.« less

Simulation based evaluation of the designs of the Advanced Gamma-ray Imageing System (AGIS)

NASA Astrophysics Data System (ADS)

Bugaev, Slava; Buckley, James; Digel, Seth; Funk, Stephen; Konopelko, Alex; Krawczynski, Henric; Lebohec, Steohan; Maier, Gernot; Vassiliev, Vladimir

2009-05-01

The AGIS project under design study, is a large array of imaging atmospheric Cherenkov telescopes for gamma-rays astronomy between 40GeV and 100 TeV. In this paper we present the ongoing simulation effort to model the considered design approaches as a function of the main parameters such as array geometry, telescope optics and camera design in such a way the gamma ray observation capabilities can be optimized against the overall project cost.

Progress in the Development of CdZnTe Unipolar Detectors for Different Anode Geometries and Data Corrections

PubMed Central

Zhang, Qiushi; Zhang, Congzhe; Lu, Yanye; Yang, Kun; Ren, Qiushi

2013-01-01

CdZnTe detectors have been under development for the past two decades, providing good stopping power for gamma rays, lightweight camera heads and improved energy resolution. However, the performance of this type of detector is limited primarily by incomplete charge collection problems resulting from charge carriers trapping. This paper is a review of the progress in the development of CdZnTe unipolar detectors with some data correction techniques for improving performance of the detectors. We will first briefly review the relevant theories. Thereafter, two aspects of the techniques for overcoming the hole trapping issue are summarized, including irradiation direction configuration and pulse shape correction methods. CdZnTe detectors of different geometries are discussed in detail, covering the principal of the electrode geometry design, the design and performance characteristics, some detector prototypes development and special correction techniques to improve the energy resolution. Finally, the state of art development of 3-D position sensing and Compton imaging technique are also discussed. Spectroscopic performance of CdZnTe semiconductor detector will be greatly improved even to approach the statistical limit on energy resolution with the combination of some of these techniques. PMID:23429509

Video-rate nanoscopy enabled by sCMOS camera-specific single-molecule localization algorithms

PubMed Central

Huang, Fang; Hartwich, Tobias M. P.; Rivera-Molina, Felix E.; Lin, Yu; Duim, Whitney C.; Long, Jane J.; Uchil, Pradeep D.; Myers, Jordan R.; Baird, Michelle A.; Mothes, Walther; Davidson, Michael W.; Toomre, Derek; Bewersdorf, Joerg

2013-01-01

Newly developed scientific complementary metal–oxide–semiconductor (sCMOS) cameras have the potential to dramatically accelerate data acquisition in single-molecule switching nanoscopy (SMSN) while simultaneously increasing the effective quantum efficiency. However, sCMOS-intrinsic pixel-dependent readout noise substantially reduces the localization precision and introduces localization artifacts. Here we present algorithms that overcome these limitations and provide unbiased, precise localization of single molecules at the theoretical limit. In combination with a multi-emitter fitting algorithm, we demonstrate single-molecule localization super-resolution imaging at up to 32 reconstructed images/second (recorded at 1,600–3,200 camera frames/second) in both fixed and living cells. PMID:23708387

Inversion of the conical Radon transform with vertices on a surface of revolution arising in an application of a Compton camera

NASA Astrophysics Data System (ADS)

Moon, Sunghwan

2017-06-01

A Compton camera has been introduced for use in single photon emission computed tomography to improve the low efficiency of a conventional gamma camera. In general, a Compton camera brings about the conical Radon transform. Here we consider a conical Radon transform with the vertices on a rotation symmetric set with respect to a coordinate axis. We show that this conical Radon transform can be decomposed into two transforms: the spherical sectional transform and the weighted fan beam transform. After finding inversion formulas for these two transforms, we provide an inversion formula for the conical Radon transform.

Effects of strain on phonon interactions and phase nucleation in several semiconductor and nano particle systems

NASA Astrophysics Data System (ADS)

Tallman, Robert E.

Raman scattering is utilized to explore the effects of applied pressure and strain on anharmonic phonon interactions and nucleation of structural transitions in several bulk and nanoparticle semiconductor systems. The systems investigated are bulk ZnS and ZnSe in several isotopic compositions, InP/CdS core/shell nanoparticles exhibiting confined and surface optical Raman modes, and amorphous selenium films undergoing photo-induced crystallization. The anharmonic decay of long-wavelength optical modes into two-phonon acoustic combinations modes is studied in 64Zn32S, 64Zn34S, natZnatS bulk crystals by measuring the TO(Gamma) Raman line-shape as a function of applied hydrostatic pressure. The experiments are carried out at room temperature and 16K for pressures up to 150 kbars using diamond-anvil cells. The most striking effects occur in 68Zn32S where the TO(Gamma) peak narrows by a factor of 10 and increases in intensity at pressures for which the TO(Gamma) frequency has been tuned into a gap in the two-phonon density of states (DOS). In all the isotopic compositions, the observed phonon decay processes can be adequately explained by a second order perturbation treatment of the anharmonic coupling between TO(Gamma) and TA + LA combinations at various critical points, combined with an adiabatic bond-charge model for the phonon DOS and the known mode Gruneisen parameters. Bulk ZnSe crystals exhibit very different behavior. Here we find that anharmonic decay alone can not explain the excessive (˜ 60 cm-1 ) broadening in the TO(Gamma) Raman peak observed as the pressure approaches to within 50kbar of the ZB -> B1 phase transition (at P ˜ 137 kbar). Rather the broadening appears to arise from antecedent nucleation of structural changes within nanoscopic domains, with the mechanism for line-shape changes being mode mixing via localization and disorder instead of anharmonicity. To sort out these contributions, pressure experiments on natural ZnSe and on isotopically pure 68Zn76Se are compared. Again we use an appropriate bond-charge model to obtain the phonon DOS. It is concluded that the antecedent nucleation mechanism is much more important in ZnSe than in ZnS. In order to further investigate interactions of vibrational modes in spatially confined systems, pressure-Raman experiments are carried out on InP/CdS core/shell nanoparticles. This system differs from most other core/shell nanoparticles systems, in that the near degeneracy of the bulk InP TO(Gamma) and CdS LO(Gamma) phonons leads to possible cross-interface mode coupling. Different confined and surface (or interface) optical modes are studied as a function of pressure up 65 kbar at 373 and 230 K. The results are compared with the predictions of dielectric continuum theory using a phenomenological macroscopic approach (PMA) to include the pressure dependence. Three different pressure media are employed, and the effects on the surface modes of their different static dielectric constants are investigated. The pressure-shifts of the observed confined and surface modes are well accounted for without the need to include cross-interface coupling. We conclude that the conventional boundary condition, of vanishing phonon amplitude at the heterointerface, remains valid in the InP/CdS nanoparticle system, in spite of the near degeneracy of the bulk optical phonons. Photo-induced crystallization in amorphous selenium (a-Se) was also explored in this dissertation, as another example of a nanoscopic nucleation process influenced by strain, in this case internal strain. In order to observe photo-crystallization, the Raman spectra of commercial a-Se films used as targets in high-gain avalanche rushing photodetectors (HARP) cameras was studied at temperatures in the range 260 - 330 K. We find a rich temperature behavior that reflects the competition of changes in viscosity and strain, and defines four distinct regimes. These results are in qualitative accord with a theory by R.B.Stephens treating the effects of local strain on the secondary growth of crystalline nuclei in a-Se. We were able to conclude that the growth of trigonal selenium is driven by local strain, and that the relaxation of this strain field around the glass transition temperature suppresses crystalline growth until thermally assisted processes accelerate the photo-crystallization at higher temperatures. The observed nucleation kinetics was also found to be relevant to understanding the formation of blemishes in the output images of advanced HARP video cameras.

[Radioactive cesium analysis in radiation-tainted beef by gamma-ray spectrometry with germanium semiconductor detector].

PubMed

Minatani, Tomiaki; Nagai, Hiroyuki; Nakamura, Masashi; Otsuka, Kimihito; Sakai, Yoshimichi

2012-01-01

The detection limit and precision of radioactive cesium measurement in beef by gamma-ray spectrometry with a germanium semiconductor detector were evaluated. Measurement for 2,000 seconds using a U-8 container (100 mL) provided a detection limit of radioactive cesium (the sum of 134Cs and 137Cs) of around 20 Bq/kg. The 99% confidence interval of the measurement of provisional maximum residue limit level (491 Bq/kg) samples ranged from 447 to 535 Bq/kg. Beef is heterogeneous, containing muscle and complex fat layers. Depending on the sampled parts, the measurement value is variable. It was found that radioactive cesium content of the muscle layer was clearly different from that of fat, and slight differences were observed among parts of the sample (SD=16.9 Bq/kg), even though the same region (neck block) of beef sample was analyzed.

Radionuclides in Diagnosis.

ERIC Educational Resources Information Center

Williams, E. D.

1989-01-01

Discussed is a radionuclide imaging technique, including the gamma camera, image analysis computer, radiopharmaceuticals, and positron emission tomography. Several pictures showing the use of this technique are presented. (YP)

Characterization of CdTe and (CdZn)Te detectors with different metal contacts

NASA Astrophysics Data System (ADS)

Pekárek, J.; Belas, E.; Grill, R.; Uxa, Å.; James, R. B.

2013-09-01

In the present work we studied an influence of different types of surface etching and surface passivation of high resistivity CdZnTe-based semiconductor detector material. The aim was to find the optimal conditions to improve the properties of metal-semiconductor contact. The main effort was to reduce the leakage current and thus get better X-ray and gamma-ray spectrum, i.e. to create a detector operating at room temperature based on this semiconductor material with sufficient energy resolution and the maximum charge collection efficiency. Individual surface treatments were characterized by I-V characteristics, spectral analysis and by determination of the profile of the internal electric field.

Impact of an external radiation field on handheld XRF measurements for nuclear forensics applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steeb, Jennifer L.; Mertz, Carol J.; Finck, Martha R.

X-ray fluorescence (XRF) is an attractive technique for nuclear forensics applications. We evaluated a handheld, portable XRF device by applying an external radiation field (10 mR/h to 17 R/h) using two types of radiography sources: a 60Co radiography camera to observe effects from high-energy gamma emissions and an 192Ir radiography camera to observe effects from several low-energy gamma (0.604, 0.468, and 0.317 MeV) and decay daughter x-ray emissions. External radiation tests proved that radiation, in general, has a significant effect on the dead time or background at dose rates over 1 R/hr for both the 192Ir and 60Co sources.

Studies on a silicon-photomultiplier-based camera for Imaging Atmospheric Cherenkov Telescopes

NASA Astrophysics Data System (ADS)

Arcaro, C.; Corti, D.; De Angelis, A.; Doro, M.; Manea, C.; Mariotti, M.; Rando, R.; Reichardt, I.; Tescaro, D.

2017-12-01

Imaging Atmospheric Cherenkov Telescopes (IACTs) represent a class of instruments which are dedicated to the ground-based observation of cosmic VHE gamma ray emission based on the detection of the Cherenkov radiation produced in the interaction of gamma rays with the Earth atmosphere. One of the key elements of such instruments is a pixelized focal-plane camera consisting of photodetectors. To date, photomultiplier tubes (PMTs) have been the common choice given their high photon detection efficiency (PDE) and fast time response. Recently, silicon photomultipliers (SiPMs) are emerging as an alternative. This rapidly evolving technology has strong potential to become superior to that based on PMTs in terms of PDE, which would further improve the sensitivity of IACTs, and see a price reduction per square millimeter of detector area. We are working to develop a SiPM-based module for the focal-plane cameras of the MAGIC telescopes to probe this technology for IACTs with large focal plane cameras of an area of few square meters. We will describe the solutions we are exploring in order to balance a competitive performance with a minimal impact on the overall MAGIC camera design using ray tracing simulations. We further present a comparative study of the overall light throughput based on Monte Carlo simulations and considering the properties of the major hardware elements of an IACT.

NEUTRON RADIATION DAMAGE IN CCD CAMERAS AT JOINT EUROPEAN TORUS (JET).

PubMed

Milocco, Alberto; Conroy, Sean; Popovichev, Sergey; Sergienko, Gennady; Huber, Alexander

2017-10-26

The neutron and gamma radiations in large fusion reactors are responsible for damage to charged couple device (CCD) cameras deployed for applied diagnostics. Based on the ASTM guide E722-09, the 'equivalent 1 MeV neutron fluence in silicon' was calculated for a set of CCD cameras at the Joint European Torus. Such evaluations would be useful to good practice in the operation of the video systems. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

An analog gamma correction scheme for high dynamic range CMOS logarithmic image sensors.

PubMed

Cao, Yuan; Pan, Xiaofang; Zhao, Xiaojin; Wu, Huisi

2014-12-15

In this paper, a novel analog gamma correction scheme with a logarithmic image sensor dedicated to minimize the quantization noise of the high dynamic applications is presented. The proposed implementation exploits a non-linear voltage-controlled-oscillator (VCO) based analog-to-digital converter (ADC) to perform the gamma correction during the analog-to-digital conversion. As a result, the quantization noise does not increase while the same high dynamic range of logarithmic image sensor is preserved. Moreover, by combining the gamma correction with the analog-to-digital conversion, the silicon area and overall power consumption can be greatly reduced. The proposed gamma correction scheme is validated by the reported simulation results and the experimental results measured for our designed test structure, which is fabricated with 0.35 μm standard complementary-metal-oxide-semiconductor (CMOS) process.

An Analog Gamma Correction Scheme for High Dynamic Range CMOS Logarithmic Image Sensors

PubMed Central

Cao, Yuan; Pan, Xiaofang; Zhao, Xiaojin; Wu, Huisi

2014-01-01

In this paper, a novel analog gamma correction scheme with a logarithmic image sensor dedicated to minimize the quantization noise of the high dynamic applications is presented. The proposed implementation exploits a non-linear voltage-controlled-oscillator (VCO) based analog-to-digital converter (ADC) to perform the gamma correction during the analog-to-digital conversion. As a result, the quantization noise does not increase while the same high dynamic range of logarithmic image sensor is preserved. Moreover, by combining the gamma correction with the analog-to-digital conversion, the silicon area and overall power consumption can be greatly reduced. The proposed gamma correction scheme is validated by the reported simulation results and the experimental results measured for our designed test structure, which is fabricated with 0.35 μm standard complementary-metal-oxide-semiconductor (CMOS) process. PMID:25517692

Compton camera study for high efficiency SPECT and benchmark with Anger system

NASA Astrophysics Data System (ADS)

Fontana, M.; Dauvergne, D.; Létang, J. M.; Ley, J.-L.; Testa, É.

2017-12-01

Single photon emission computed tomography (SPECT) is at present one of the major techniques for non-invasive diagnostics in nuclear medicine. The clinical routine is mostly based on collimated cameras, originally proposed by Hal Anger. Due to the presence of mechanical collimation, detection efficiency and energy acceptance are limited and fixed by the system’s geometrical features. In order to overcome these limitations, the application of Compton cameras for SPECT has been investigated for several years. In this study we compare a commercial SPECT-Anger device, the General Electric HealthCare Infinia system with a High Energy General Purpose (HEGP) collimator, and the Compton camera prototype under development by the French collaboration CLaRyS, through Monte Carlo simulations (GATE—GEANT4 Application for Tomographic Emission—version 7.1 and GEANT4 version 9.6, respectively). Given the possible introduction of new radio-emitters at higher energies intrinsically allowed by the Compton camera detection principle, the two detectors are exposed to point-like sources at increasing primary gamma energies, from actual isotopes already suggested for nuclear medicine applications. The Compton camera prototype is first characterized for SPECT application by studying the main parameters affecting its imaging performance: detector energy resolution and random coincidence rate. The two detector performances are then compared in terms of radial event distribution, detection efficiency and final image, obtained by gamma transmission analysis for the Anger system, and with an iterative List Mode-Maximum Likelihood Expectation Maximization (LM-MLEM) algorithm for the Compton reconstruction. The results show for the Compton camera a detection efficiency increased by a factor larger than an order of magnitude with respect to the Anger camera, associated with an enhanced spatial resolution for energies beyond 500 keV. We discuss the advantages of Compton camera application for SPECT if compared to present commercial Anger systems, with particular focus on dose delivered to the patient, examination time, and spatial uncertainties.

Nanotribology Investigations of Solid and Liquid Lubricants Using Scanned Probe Microscopies

DTIC Science & Technology

2000-01-28

Kai Rose, postdoctoral fellow (external fellowship support; supplies on AFOSR) 7. Ernesto Joselevich, postdoctoral fellow (external fellowship...scale friction measurements", European Semiconductor, July/August 1997. 2. I. Amato , "Candid Cameras for the Nanoworld," Science 276, 1982-1985 (1997

Note: A disposable x-ray camera based on mass produced complementary metal-oxide-semiconductor sensors and single-board computers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoidn, Oliver R.; Seidler, Gerald T., E-mail: seidler@uw.edu

We have integrated mass-produced commercial complementary metal-oxide-semiconductor (CMOS) image sensors and off-the-shelf single-board computers into an x-ray camera platform optimized for acquisition of x-ray spectra and radiographs at energies of 2–6 keV. The CMOS sensor and single-board computer are complemented by custom mounting and interface hardware that can be easily acquired from rapid prototyping services. For single-pixel detection events, i.e., events where the deposited energy from one photon is substantially localized in a single pixel, we establish ∼20% quantum efficiency at 2.6 keV with ∼190 eV resolution and a 100 kHz maximum detection rate. The detector platform’s useful intrinsic energymore » resolution, 5-μm pixel size, ease of use, and obvious potential for parallelization make it a promising candidate for many applications at synchrotron facilities, in laser-heating plasma physics studies, and in laboratory-based x-ray spectrometry.« less

Directional Unfolded Source Term (DUST) for Compton Cameras.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Dean J.; Horne, Steven M.; O'Brien, Sean

2018-03-01

A Directional Unfolded Source Term (DUST) algorithm was developed to enable improved spectral analysis capabilities using data collected by Compton cameras. Achieving this objective required modification of the detector response function in the Gamma Detector Response and Analysis Software (GADRAS). Experimental data that were collected in support of this work include measurements of calibration sources at a range of separation distances and cylindrical depleted uranium castings.

Gamma ray detector modules

NASA Technical Reports Server (NTRS)

Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

2009-01-01

A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.

Electron gas grid semiconductor radiation detectors

DOEpatents

Lee, Edwin Y.; James, Ralph B.

2002-01-01

An electron gas grid semiconductor radiation detector (EGGSRAD) useful for gamma-ray and x-ray spectrometers and imaging systems is described. The radiation detector employs doping of the semiconductor and variation of the semiconductor detector material to form a two-dimensional electron gas, and to allow transistor action within the detector. This radiation detector provides superior energy resolution and radiation detection sensitivity over the conventional semiconductor radiation detector and the "electron-only" semiconductor radiation detectors which utilize a grid electrode near the anode. In a first embodiment, the EGGSRAD incorporates delta-doped layers adjacent the anode which produce an internal free electron grid well to which an external grid electrode can be attached. In a second embodiment, a quantum well is formed between two of the delta-doped layers, and the quantum well forms the internal free electron gas grid to which an external grid electrode can be attached. Two other embodiments which are similar to the first and second embodiment involve a graded bandgap formed by changing the composition of the semiconductor material near the first and last of the delta-doped layers to increase or decrease the conduction band energy adjacent to the delta-doped layers.

IR observations in gamma-ray blazars

NASA Technical Reports Server (NTRS)

Mahoney, W. A.; Gautier, T. N.; Ressler, M. E.; Wallyn, P.; Durouchoux, P.; Higdon, J. C.

1997-01-01

The infrared photometric and spectral observation of five gamma ray blazars in coordination with the energetic gamma ray experiment telescope (EGRET) onboard the Compton Gamma Ray Observatory is reported. The infrared measurements were made with a Cassegrain infrared camera and the mid-infrared large well imager at the Mt. Palomar 5 m telescope. The emphasis is on the three blazars observed simultaneously by EGRET and the ground-based telescope during viewing period 519. In addition to the acquisition of broadband spectral measurements for direct correlation with the 100 MeV EGRET observations, near infrared images were obtained, enabling a search for intra-day variability to be carried out.

Toward Simultaneous Real-Time Fluoroscopic and Nuclear Imaging in the Intervention Room.

PubMed

Beijst, Casper; Elschot, Mattijs; Viergever, Max A; de Jong, Hugo W A M

2016-01-01

To investigate the technical feasibility of hybrid simultaneous fluoroscopic and nuclear imaging. An x-ray tube, an x-ray detector, and a gamma camera were positioned in one line, enabling imaging of the same field of view. Since a straightforward combination of these elements would block the lines of view, a gamma camera setup was developed to be able to view around the x-ray tube. A prototype was built by using a mobile C-arm and a gamma camera with a four-pinhole collimator. By using the prototype, test images were acquired and sensitivity, resolution, and coregistration error were analyzed. Nuclear images (two frames per second) were acquired simultaneously with fluoroscopic images. Depending on the distance from point source to detector, the system resolution was 1.5-1.9-cm full width at half maximum, the sensitivity was (0.6-1.5) × 10(-5) counts per decay, and the coregistration error was -0.13 to 0.15 cm. With good spatial and temporal alignment of both modalities throughout the field of view, fluoroscopic images can be shown in grayscale and corresponding nuclear images in color overlay. Measurements obtained with the hybrid imaging prototype device that combines simultaneous fluoroscopic and nuclear imaging of the same field of view have demonstrated the feasibility of real-time simultaneous hybrid imaging in the intervention room. © RSNA, 2015

Intraoperative Imaging Guidance for Sentinel Node Biopsy in Melanoma Using a Mobile Gamma Camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dengel, Lynn T; Judy, Patricia G; Petroni, Gina R

2011-04-01

The objective is to evaluate the sensitivity and clinical utility of intraoperative mobile gamma camera (MGC) imaging in sentinel lymph node biopsy (SLNB) in melanoma. The false-negative rate for SLNB for melanoma is approximately 17%, for which failure to identify the sentinel lymph node (SLN) is a major cause. Intraoperative imaging may aid in detection of SLN near the primary site, in ambiguous locations, and after excision of each SLN. The present pilot study reports outcomes with a prototype MGC designed for rapid intraoperative image acquisition. We hypothesized that intraoperative use of the MGC would be feasible and that sensitivitymore » would be at least 90%. From April to September 2008, 20 patients underwent Tc99 sulfur colloid lymphoscintigraphy, and SLNB was performed with use of a conventional fixed gamma camera (FGC), and gamma probe followed by intraoperative MGC imaging. Sensitivity was calculated for each detection method. Intraoperative logistical challenges were scored. Cases in which MGC provided clinical benefit were recorded. Sensitivity for detecting SLN basins was 97% for the FGC and 90% for the MGC. A total of 46 SLN were identified: 32 (70%) were identified as distinct hot spots by preoperative FGC imaging, 31 (67%) by preoperative MGC imaging, and 43 (93%) by MGC imaging pre- or intraoperatively. The gamma probe identified 44 (96%) independent of MGC imaging. The MGC provided defined clinical benefit as an addition to standard practice in 5 (25%) of 20 patients. Mean score for MGC logistic feasibility was 2 on a scale of 1-9 (1 = best). Intraoperative MGC imaging provides additional information when standard techniques fail or are ambiguous. Sensitivity is 90% and can be increased. This pilot study has identified ways to improve the usefulness of an MGC for intraoperative imaging, which holds promise for reducing false negatives of SLNB for melanoma.« less

Septal penetration correction in I-131 imaging following thyroid cancer treatment

NASA Astrophysics Data System (ADS)

Barrack, Fiona; Scuffham, James; McQuaid, Sarah

2018-04-01

Whole body gamma camera images acquired after I-131 treatment for thyroid cancer can suffer from collimator septal penetration artefacts because of the high energy of the gamma photons. This results in the appearance of ‘spoke’ artefacts, emanating from regions of high activity concentration, caused by the non-isotropic attenuation of the collimator. Deconvolution has the potential to reduce such artefacts, by taking into account the non-Gaussian point-spread-function (PSF) of the system. A Richardson–Lucy deconvolution algorithm, with and without prior scatter-correction was tested as a method of reducing septal penetration in planar gamma camera images. Phantom images (hot spheres within a warm background) were acquired and deconvolution using a measured PSF was applied. The results were evaluated through region-of-interest and line profile analysis to determine the success of artefact reduction and the optimal number of deconvolution iterations and damping parameter (λ). Without scatter-correction, the optimal results were obtained with 15 iterations and λ  =  0.01, with the counts in the spokes reduced to 20% of the original value, indicating a substantial decrease in their prominence. When a triple-energy-window scatter-correction was applied prior to deconvolution, the optimal results were obtained with six iterations and λ  =  0.02, which reduced the spoke counts to 3% of the original value. The prior application of scatter-correction therefore produced the best results, with a marked change in the appearance of the images. The optimal settings were then applied to six patient datasets, to demonstrate its utility in the clinical setting. In all datasets, spoke artefacts were substantially reduced after the application of scatter-correction and deconvolution, with the mean spoke count being reduced to 10% of the original value. This indicates that deconvolution is a promising technique for septal penetration artefact reduction that could potentially improve the diagnostic accuracy of I-131 imaging. Novelty and significance This work has demonstrated that scatter correction combined with deconvolution can be used to substantially reduce the appearance of septal penetration artefacts in I-131 phantom and patient gamma camera planar images, enable improved visualisation of the I-131 distribution. Deconvolution with symmetric PSF has previously been used to reduce artefacts in gamma camera images however this work details the novel use of an asymmetric PSF to remove the angularly dependent septal penetration artefacts.

Coincidence ion imaging with a fast frame camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Suk Kyoung; Cudry, Fadia; Lin, Yun Fei

2014-12-15

A new time- and position-sensitive particle detection system based on a fast frame CMOS (complementary metal-oxide semiconductors) camera is developed for coincidence ion imaging. The system is composed of four major components: a conventional microchannel plate/phosphor screen ion imager, a fast frame CMOS camera, a single anode photomultiplier tube (PMT), and a high-speed digitizer. The system collects the positional information of ions from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of a PMT processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of ion spots onmore » each camera frame with the peak heights on the corresponding time-of-flight spectrum of a PMT. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide.« less

Our solution for fusion of simultaneusly acquired whole body scintigrams and optical images, as usesful tool in clinical practice in patients with differentiated thyroid carcinomas after radioiodine therapy. A useful tool in clinical practice.

PubMed

Matovic, Milovan; Jankovic, Milica; Barjaktarovic, Marko; Jeremic, Marija

2017-01-01

After radioiodine therapy of differentiated thyroid cancer (DTC) patients, whole body scintigraphy (WBS) is standard procedure before releasing the patient from the hospital. A common problem is the precise localization of regions where the iod-avide tissue is located. Sometimes is practically impossible to perform precise topographic localization of such regions. In order to face this problem, we have developed a low-cost Vision-Fusion system for web-camera image acquisition simultaneously with routine scintigraphic whole body acquisition including the algorithm for fusion of images given from both cameras. For image acquisition in the gamma part of the spectra we used e.cam dual head gamma camera (Siemens, Erlangen, Germany) in WBS modality, with matrix size of 256×1024 pixels and bed speed of 6cm/min, equipped with high energy collimator. For optical image acquisition in visible part of spectra we have used web-camera model C905 (Logitech, USA) with Carl Zeiss® optics, native resolution 1600×1200 pixels, 34 o field of view, 30g weight, with autofocus option turned "off" and auto white balance turned "on". Web camera is connected to upper head of gamma camera (GC) by a holder of lightweight aluminum rod and a plexiglas adapter. Our own Vision-Fusion software for image acquisition and coregistration was developed using NI LabVIEW programming environment 2015 (National Instruments, Texas, USA) and two additional LabVIEW modules: NI Vision Acquisition Software (VAS) and NI Vision Development Module (VDM). Vision acquisition software enables communication and control between laptop computer and web-camera. Vision development module is image processing library used for image preprocessing and fusion. Software starts the web-camera image acquisition before starting image acquisition on GC and stops it when GC completes the acquisition. Web-camera is in continuous acquisition mode with frame rate f depending on speed of patient bed movement v (f=v/∆ cm , where ∆ cm is a displacement step that can be changed in Settings option of Vision-Fusion software; by default, ∆ cm is set to 1cm corresponding to ∆ p =15 pixels). All images captured while patient's bed is moving are processed. Movement of patient's bed is checked using cross-correlation of two successive images. After each image capturing, algorithm extracts the central region of interest (ROI) of the image, with the same width as captured image (1600 pixels) and the height that is equal to the ∆ p displacement in pixels. All extracted central ROI are placed next to each other in the overall whole-body image. Stacking of narrow central ROI introduces negligible distortion in the overall whole-body image. The first step for fusion of the scintigram and the optical image was determination of spatial transformation between them. We have made an experiment with two markers (point radioactivity sources of 99m Tc pertechnetate 1MBq) visible in both images (WBS and optical) to find transformation of coordinates between images. The distance between point markers is used for spatial coregistration of the gamma and optical images. At the end of coregistration process, gamma image is rescaled in spatial domain and added to the optical image (green or red channel, amplification changeable from user interface). We tested our system for 10 patients with DTC who received radioiodine therapy (8 women and two men, with average age of 50.10±12.26 years). Five patients received 5.55Gbq, three 3.70GBq and two 1.85GBq. Whole-body scintigraphy and optical image acquisition were performed 72 hours after application of radioiodine therapy. Based on our first results during clinical testing of our system, we can conclude that our system can improve diagnostic possibility of whole body scintigraphy to detect thyroid remnant tissue in patients with DTC after radioiodine therapy.

Europe's space camera unmasks a cosmic gamma-ray machine

NASA Astrophysics Data System (ADS)

1996-11-01

The new-found neutron star is the visible counterpart of a pulsating radio source, Pulsar 1055-52. It is a mere 20 kilometres wide. Although the neutron star is very hot, at about a million degrees C, very little of its radiant energy takes the form of visible light. It emits mainly gamma-rays, an extremely energetic form of radiation. By examining it at visible wavelengths, astronomers hope to figure out why Pulsar 1055-52 is the most efficient generator of gamma-rays known so far, anywhere the Universe. The Faint Object Camera found Pulsar 1055-52 in near ultraviolet light at 3400 angstroms, a little shorter in wavelength than the violet light at the extremity of the human visual range. Roberto Mignani, Patrizia Caraveo and Giovanni Bignami of the Istituto di Fisica Cosmica in Milan, Italy, report its optical identification in a forthcoming issue of Astrophysical Journal Letters (1 January 1997). The formal name of the object is PSR 1055-52. Evading the glare of an adjacent star The Italian team had tried since 1988 to spot Pulsar 1055-52 with two of the most powerful ground-based optical telescopes in the Southern Hemisphere. These were the 3.6-metre Telescope and the 3.5-metre New Technology Telescope of the European Southern Observatory at La Silla, Chile. Unfortunately an ordinary star 100,000 times brighter lay in almost the same direction in the sky, separated from the neutron star by only a thousandth of a degree. The Earth's atmosphere defocused the star's light sufficiently to mask the glimmer from Pulsar 1055-52. The astronomers therefore needed an instrument in space. The Faint Object Camera offered the best precision and sensitivity to continue the hunt. Devised by European astronomers to complement the American wide field camera in the Hubble Space Telescope, the Faint Object Camera has a relatively narrow field of view. It intensifies the image of a faint object by repeatedly accelerating electrons from photo-electric films, so as to produce brighter flashes when the electrons hit a phosphor screen. Since Hubble's launch in 1990, the Faint Object Camera has examined many different kinds of cosmic objects, from the moons of Jupiter to remote galaxies and quasars. When the space telescope's optics were corrected at the end of 1993 the Faint Object Camera immediately celebrated the event with the discovery of primeval helium in intergalactic gas. In their search for Pulsar 1055-52, the astronomers chose a near-ultraviolet filter to sharpen the Faint Object Camera's vision and reduce the adjacent star's huge advantage in intensity. In May 1996, the Hubble Space Telescope operators aimed at the spot which radio astronomers had indicated, as the source of the radio pulsations of Pulsar 1055-52. The neutron star appeared precisely in the centre of the field of view, and it was clearly separated from the glare of the adjacent star. At magnitude 24.9, Pulsar 1055-52 was comfortably within the power of the Faint Object Camera, which can see stars 20 times fainter still. "The Faint Object Camera is the instrument of choice for looking for neutron stars," says Giovanni Bignami, speaking on behalf of the Italian team. "Whenever it points to a judiciously selected neutron star it detects the corresponding visible or ultraviolet light. The Faint Object Camera has now identified three neutron stars in that way, including Pulsar 1055-52, and it has examined a few that were first detected by other instruments." Mysteries of the neutron stars The importance of the new result can be gauged by the tally of only eight neutron stars seen so far at optical wavelengths, compared with about 760 known from their radio pulsations, and about 21 seen emitting X-rays. Since the first pulsar was detected by radio astronomers in Cambridge, England, nearly 30 years ago, theorists have come to recognize neutron stars as fantastic objects. They are veritable cosmic laboratories in which Nature reveals the behaviour of matter under extreme stress, just one step short of a black hole. A neutron star is created by the force of a supernova explosion in a large star, which crushes the star's core to an unimaginable density. A mass greater than the Sun's is squeezed into a ball no wider than a city. The gravity and magnetic fields are billions of times stronger than the Earth's. The neutron star revolves rapidly, which causes it to wink like a cosmic lighthouse as it swivels its magnetic poles towards and away from the Earth. Pulsar 1055-52 spins at five revolutions per second. At its formation in a supernova explosion, a neutron star is endowed with two main forms of energy. One is heat, at temperatures of millions of degrees, which the neutron star radiates mainly as X-rays, with only a small proportion emerging as visible light. The other power supply for the neutron star comes from its high rate of spin and a gradual slowing of the rotation. By a variety of processes involving the magnetic field and accelerated particles in the neutron star's vicinity, the spin energy of the neutron star is converted into radiation at many different wavelengths, from radio waves to gamma-rays. The exceptional gamma-ray intensity of Pulsar 1055-52 was first appreciated in observations by NASA's Compton Gamma Ray Observatory. The team in Milan recently used the Hubble Space Telescope to find the distance of the peculiar neutron star Geminga, which is not detectable by radio pulses but is a strong source of gamma-rays (see ESA Information Note 04-96, 28 March 1996). Pulsar 1055-52 is even more powerful in that respect. About 50 per cent of its radiant energy is gamma-rays, compared with 15 per cent from Geminga and 0.1 per cent from the famous Crab Pulsar, the first neutron star seen by visible light. Making the gamma-rays requires the acceleration of electrons through billions of volts. The magnetic environment of Pulsar 1055-52 fashions a natural gamma-ray machine of amazing power. The orientation of the neutron star's magnetic field with respect to the Earth may contribute to its brightness in gamma-rays. Geminga, Pulsar 1055-52 and another object, Pulsar 0656+14, make a trio that the Milanese astronomers call the Three Musketeers. All have been observed with the Faint Object Camera. They are isolated, elderly neutron stars, some hundreds of thousands of years old, contrasting with the 942 year-old Crab Pulsar which is still surrounded by dispersing debris of a supernova seen by Chinese astronomers in the 11th Century. The mysteries of the neutron stars will keep astronomers busy for years to come, and the Faint Object Camera in the Hubble Space Telescope will remain the best instrument for spotting their faint visible light. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Maryland. Note to editors: An image is available of (i) PSR 1055-52 seen by ESA's Faint Object Camera in the Hubble Space Telescope, and (ii) the same region of the sky seen by the European Southern Observatory's New Technology Telescope, with the position of PSR 1055-52 indicated. The image is available on the World Wide Web at http://ecf.hq.eso.org/stecf-pubrel.html http://www.estec.esa.nl/spdwww/h2000/html/snlmain.htm

The effect of guar gum and fiber-enriched wheat bran on gastric emptying of a semisolid meal in healthy subjects.

PubMed

Rydning, A; Berstad, A; Berstad, T; Hertzenberg, L

1985-04-01

The effect of physiological doses of guar gum (Guarem), 5 g, and fiber-enriched wheat bran (Fiberform), 10.5 g, on gastric emptying was studied by two different methods in healthy subjects: by a simple isotope localization monitor placed over the upper part of the abdomen and by gamma camera. The fiber preparations were added to a semisolid meal consisting of wheatmeal porridge and juice, using technetium-99 DTPA as a marker. The gamma camera showed no effect of fiber on gastric emptying. The isotope localization monitor, however, indicated that Fiberform prevented a postprandial accumulation of the meal within the upper part of the stomach. The simple isotope localization monitor cannot be recommended for measurements of gastric emptying.

Impact of New Camera Technologies on Discoveries in Cell Biology.

PubMed

Stuurman, Nico; Vale, Ronald D

2016-08-01

New technologies can make previously invisible phenomena visible. Nowhere is this more obvious than in the field of light microscopy. Beginning with the observation of "animalcules" by Antonie van Leeuwenhoek, when he figured out how to achieve high magnification by shaping lenses, microscopy has advanced to this day by a continued march of discoveries driven by technical innovations. Recent advances in single-molecule-based technologies have achieved unprecedented resolution, and were the basis of the Nobel prize in Chemistry in 2014. In this article, we focus on developments in camera technologies and associated image processing that have been a major driver of technical innovations in light microscopy. We describe five types of developments in camera technology: video-based analog contrast enhancement, charge-coupled devices (CCDs), intensified sensors, electron multiplying gain, and scientific complementary metal-oxide-semiconductor cameras, which, together, have had major impacts in light microscopy. © 2016 Marine Biological Laboratory.

[Results of the EGRET Detector Program

NASA Technical Reports Server (NTRS)

Carter-Lewis, D. A.

1998-01-01

This NASA grant has funded studies of cosmic objects observed by both the EGRET detector aboard the Compton Gamma-ray Observatory and Whipple Gamma-ray imaging telescope. The former has sensitivity up to a few GeV and latter has sensitivity starting at about 200 GeV extending up to beyond 10 TeV. Thus these instruments probe some of the most energetic phenomena in the universe. This program has been in place for several years and led to important results referred to below. The Whipple Observatory Imaging Cherenkov Telescope consists of a 10-meter reflector with a nanosecond photomultiplier-tube camera at the focal plane. During the time period covered by this grant, it had either 109 pixels or 151 pixels on a 1/4 degree hexagonal pattern. As a TeV gamma ray enters the atmosphere, it produces an electron/positron pair initiating an extensive air shower. Cherenkov light from the electrons and positrons in the shower form an image of the shower at the phototube camera. The shape and intensity of this image is used to distinguish gamma-ray initiated showers from cosmic-ray (largely proton and alpha-particle) background showers and to derive an energy estimate for the primary gamma-ray. The Whipple Observatory gamma-ray collaboration pioneered this imaging technique which normally rejects over 99 percent of the cosmic-ray background while keeping over 70 percent of the gamma-ray signal. One of its key features is 2 large collection area which can exceed 50,000 meters. This grant covered primarily correlated observations of Markarian 421 and observations of the Cygnus region. The former resulted in a multiwavelength campaign showing correlations in several wavebands. The TeV data showed dramatic variability with the emission characterized by day-scale flickering and with now well defined steady component.

SiPM detectors for the ASTRI project in the framework of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Billotta, Sergio; Marano, Davide; Bonanno, Giovanni; Belluso, Massimiliano; Grillo, Alessandro; Garozzo, Salvatore; Romeo, Giuseppe; Timpanaro, Maria Cristina; Maccarone, Maria Concetta C.; Catalano, Osvaldo; La Rosa, Giovanni; Sottile, Giuseppe; Impiombato, Domenico; Gargano, Carmelo; Giarrusso, Salavtore

2014-07-01

The Cherenkov Telescope Array (CTA) is a worldwide new generation project aimed at realizing an array of a hundred ground based gamma-ray telescopes. ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is the Italian project whose primary target is the development of an end-to-end prototype, named ASTRI SST-2M, of the CTA small size class of telescopes devoted to investigation of the highest energy region, from 1 to 100 TeV. Next target is the implementation of an ASTRI/CTA mini-array based on seven identical telescopes. Silicon Photo-Multipliers (SiPMs) are the semiconductor photosensor devices designated to constitute the camera detection system at the focal plane of the ASTRI telescopes. SiPM photosensors are suitable for the detection of the Cherenkov flashes, since they are very fast and sensitive to the light in the 300-700nm wavelength spectrum. Their drawbacks compared to the traditional photomultiplier tubes are high dark count rates, after-pulsing and optical cross-talk contributions, and intrinsic gains strongly dependent on temperature. Nonetheless, for a single pixel, the dark count rate is well below the Night Sky Background, the effects of cross-talk and afterpulses are typically lower than 20%, and the gain can be kept stable against temperature variations by means of adequate bias voltage compensation strategies. This work presents and discusses some experimental results from a large set of measurements performed on the SiPM sensors to be used for the ASTRI SST-2M prototype camera and on recently developed detectors demonstrating outstanding performance for the future evolution of the project in the ASTRI/CTA mini-array.

Positron emission particle tracking using a modular positron camera

NASA Astrophysics Data System (ADS)

Parker, D. J.; Leadbeater, T. W.; Fan, X.; Hausard, M. N.; Ingram, A.; Yang, Z.

2009-06-01

The technique of positron emission particle tracking (PEPT), developed at Birmingham in the early 1990s, enables a radioactively labelled tracer particle to be accurately tracked as it moves between the detectors of a "positron camera". In 1999 the original Birmingham positron camera, which consisted of a pair of MWPCs, was replaced by a system comprising two NaI(Tl) gamma camera heads operating in coincidence. This system has been successfully used for PEPT studies of a wide range of granular and fluid flow processes. More recently a modular positron camera has been developed using a number of the bismuth germanate (BGO) block detectors from standard PET scanners (CTI ECAT 930 and 950 series). This camera has flexible geometry, is transportable, and is capable of delivering high data rates. This paper presents simple models of its performance, and initial experience of its use in a range of geometries and applications.

Design and realization of an AEC&AGC system for the CCD aerial camera

NASA Astrophysics Data System (ADS)

Liu, Hai ying; Feng, Bing; Wang, Peng; Li, Yan; Wei, Hao yun

2015-08-01

An AEC and AGC(Automatic Exposure Control and Automatic Gain Control) system was designed for a CCD aerial camera with fixed aperture and electronic shutter. The normal AEC and AGE algorithm is not suitable to the aerial camera since the camera always takes high-resolution photographs in high-speed moving. The AEC and AGE system adjusts electronic shutter and camera gain automatically according to the target brightness and the moving speed of the aircraft. An automatic Gamma correction is used before the image is output so that the image is better for watching and analyzing by human eyes. The AEC and AGC system could avoid underexposure, overexposure, or image blurring caused by fast moving or environment vibration. A series of tests proved that the system meet the requirements of the camera system with its fast adjusting speed, high adaptability, high reliability in severe complex environment.

Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

DOEpatents

Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

2014-12-30

A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

Handheld dual thermal neutron detector and gamma-ray spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stowe, Ashley C.; Burger, Arnold; Bhattacharya, Pijush

2017-05-02

A combined thermal neutron detector and gamma-ray spectrometer system, including: a first detection medium including a lithium chalcopyrite crystal operable for detecting neutrons; a gamma ray shielding material disposed adjacent to the first detection medium; a second detection medium including one of a doped metal halide, an elpasolite, and a high Z semiconductor scintillator crystal operable for detecting gamma rays; a neutron shielding material disposed adjacent to the second detection medium; and a photodetector coupled to the second detection medium also operable for detecting the gamma rays; wherein the first detection medium and the second detection medium do not overlapmore » in an orthogonal plane to a radiation flux. Optionally, the first detection medium includes a .sup.6LiInSe.sub.2 crystal. Optionally, the second detection medium includes a SrI.sub.2(Eu) scintillation crystal.« less

The High Definition Earth Viewing (HDEV) Payload

NASA Technical Reports Server (NTRS)

Muri, Paul; Runco, Susan; Fontanot, Carlos; Getteau, Chris

2017-01-01

The High Definition Earth Viewing (HDEV) payload enables long-term experimentation of four, commercial-of-the-shelf (COTS) high definition video, cameras mounted on the exterior of the International Space Station. The payload enables testing of cameras in the space environment. The HDEV cameras transmit imagery continuously to an encoder that then sends the video signal via Ethernet through the space station for downlink. The encoder, cameras, and other electronics are enclosed in a box pressurized to approximately one atmosphere, containing dry nitrogen, to provide a level of protection to the electronics from the space environment. The encoded video format supports streaming live video of Earth for viewing online. Camera sensor types include charge-coupled device and complementary metal-oxide semiconductor. Received imagery data is analyzed on the ground to evaluate camera sensor performance. Since payload deployment, minimal degradation to imagery quality has been observed. The HDEV payload continues to operate by live streaming and analyzing imagery. Results from the experiment reduce risk in the selection of cameras that could be considered for future use on the International Space Station and other spacecraft. This paper discusses the payload development, end-to- end architecture, experiment operation, resulting image analysis, and future work.

Layered semiconductor neutron detectors

DOEpatents

Mao, Samuel S; Perry, Dale L

2013-12-10

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Simulation study of the second-generation MR-compatible SPECT system based on the inverted compound-eye gamma camera design

NASA Astrophysics Data System (ADS)

Lai, Xiaochun; Meng, Ling-Jian

2018-02-01

In this paper, we present simulation studies for the second-generation MRI compatible SPECT system, MRC-SPECT-II, based on an inverted compound eye (ICE) gamma camera concept. The MRC-SPECT-II system consists of a total of 1536 independent micro-pinhole-camera-elements (MCEs) distributed in a ring with an inner diameter of 6 cm. This system provides a FOV of 1 cm diameter and a peak geometrical efficiency of approximately 1.3% (the typical levels of 0.1%-0.01% found in modern pre-clinical SPECT instrumentations), while maintaining a sub-500 μm spatial resolution. Compared to the first-generation MRC-SPECT system (MRC-SPECT-I) (Cai 2014 Nucl. Instrum. Methods Phys. Res. A 734 147-51) developed in our lab, the MRC-SPECT-II system offers a similar resolution with dramatically improved sensitivity and greatly reduced physical dimension. The latter should allow the system to be placed inside most clinical and pre-clinical MRI scanners for high-performance simultaneous MRI and SPECT imaging.

Dual-modality imaging with a ultrasound-gamma device for oncology

NASA Astrophysics Data System (ADS)

Polito, C.; Pellegrini, R.; Cinti, M. N.; De Vincentis, G.; Lo Meo, S.; Fabbri, A.; Bennati, P.; Cencelli, V. Orsolini; Pani, R.

2018-06-01

Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping oncological or surgical treatments. Moreover, due to the growing interest in handheld detectors for preclinical trials or small animal imaging, in this work a new dual modality integrated device, based on a Ultrasounds probe and a small Field of View Single Photon Emission gamma camera, is proposed.

Gamma-Ray Imaging for Explosives Detection

NASA Technical Reports Server (NTRS)

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

2008-01-01

We describe a gamma-ray imaging camera (GIC) for active interrogation of explosives being developed by NASA/GSFC and NSWCICarderock. The GIC is based on the Three-dimensional Track Imager (3-DTI) technology developed at GSFC for gamma-ray astrophysics. The 3-DTI, a large volume time-projection chamber, provides accurate, approx.0.4 mm resolution, 3-D tracking of charged particles. The incident direction of gamma rays, E, > 6 MeV, are reconstructed from the momenta and energies of the electron-positron pair resulting from interactions in the 3-DTI volume. The optimization of the 3-DTI technology for this specific application and the performance of the GIC from laboratory tests is presented.

Breathing synchronized assessment of the chest hemodynamics: application to gamma and MR angiography

NASA Astrophysics Data System (ADS)

Eclancher, Bernard; Demangeat, Jean-Louis; Germain, Philippe; Baruthio, Joseph

2003-05-01

The project was to assess by gamma and MR angiography the bulk variations of chest blood volume related to deep and slow breathing movements. The acquisitions were performed at constant intervals on the widely moving system, without cardiac gating. Two fast enough modalities were used: a gamma-stethoscope working at 30 msec intervals for bulk volumic detection (of 99Tc labelled red cells), and MR imaging at 0.5 sec intervals well depicting displacements but not yet performing true angiography. The third modality yielding quantitative imaging was the scintillation gamma camera, but which required 30 sec signal acquisitions for each image. Frames were acquired at 1 sec intervals for up to 30 breathing cycles, and later sorted with double (inspiration and expiration) synchronization for the reconstruction of an average breathing cycle. Convergent results were obtained from the three angiographic modalities, confirming that the deep breathing movements produced inspiratory increases in bulk blood volume and caudal-median displacement of heart and great vessels, and expiratory decreases in blood volume and cranial-left displacement of heart and great vessels. Deep and slow breathing contributed effectively to thoracic blood pumping. The design of a 64x64 channels collimator has been undertaken to speed up the scintillation camera imaging acquisitions.

High-resolution CdTe detectors with application to various fields (Conference Presentation)

NASA Astrophysics Data System (ADS)

Takeda, Shin'ichiro; Orita, Tadashi; Arai, Yasuo; Sugawara, Hirotaka; Tomaru, Ryota; Katsuragawa, Miho; Sato, Goro; Watanabe, Shin; Ikeda, Hirokazu; Takahashi, Tadayuki; Furenlid, Lars R.; Barber, H. Bradford

2016-10-01

High-quality CdTe semiconductor detectors with both fine position resolution and high energy resolution hold great promise to improve measurement in various hard X-ray and gamma-ray imaging fields. ISAS/JAXA has been developing CdTe imaging detectors to meet scientific demands in latest celestial observation and severe environmental limitation (power consumption, vibration, radiation) in space for over 15 years. The energy resolution of imaging detectors with a CdTe Schottky diode of In/CdTe/Pt or Al/CdTe/Pt contact is a highlight of our development. We can extremely reduce a leakage current of devises, meaning it allows us to supply higher bias voltage to collect charges. The 3.2cm-wide and 0.75mm-thick CdTe double-sided strip detector with a strip pitch of 250 µm has been successfully established and was mounted in the latest Japanese X-ray satellite. The energy resolution measured in the test on ground was 2.1 keV (FWHM) at 59.5 keV. The detector with much finer resolution of 60 µm is ready, and it was actually used in the FOXSI rocket mission to observe hard X-ray from the sun. In this talk, we will focus on our research activities to apply space sensor technologies to such various imaging fields as medical imaging. Recent development of CdTe detectors, imaging module with pinhole and coded-mask collimators, and experimental study of response to hard X-rays and gamma-rays are presented. The talk also includes research of the Compton camera which has a configuration of accumulated Si and CdTe imaging detectors.

MO-AB-206-00: Nuclear Medicine Physics and Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Concept of a photon-counting camera based on a diffraction-addressed Gray-code mask

NASA Astrophysics Data System (ADS)

Morel, Sébastien

2004-09-01

A new concept of photon counting camera for fast and low-light-level imaging applications is introduced. The possible spectrum covered by this camera ranges from visible light to gamma rays, depending on the device used to transform an incoming photon into a burst of visible photons (photo-event spot) localized in an (x,y) image plane. It is actually an evolution of the existing "PAPA" (Precision Analog Photon Address) Camera that was designed for visible photons. This improvement comes from a simplified optics. The new camera transforms, by diffraction, each photo-event spot from an image intensifier or a scintillator into a cross-shaped pattern, which is projected onto a specific Gray code mask. The photo-event position is then extracted from the signal given by an array of avalanche photodiodes (or photomultiplier tubes, alternatively) downstream of the mask. After a detailed explanation of this camera concept that we have called "DIAMICON" (DIffraction Addressed Mask ICONographer), we briefly discuss about technical solutions to build such a camera.

Test apparatus to monitor time-domain signals from semiconductor-detector pixel arrays

NASA Astrophysics Data System (ADS)

Haston, Kyle; Barber, H. Bradford; Furenlid, Lars R.; Salçin, Esen; Bora, Vaibhav

2011-10-01

Pixellated semiconductor detectors, such as CdZnTe, CdTe, or TlBr, are used for gamma-ray imaging in medicine and astronomy. Data analysis for these detectors typically estimates the position (x, y, z) and energy (E) of each interacting gamma ray from a set of detector signals {Si} corresponding to completed charge transport on the hit pixel and any of its neighbors that take part in charge sharing, plus the cathode. However, it is clear from an analysis of signal induction, that there are transient signal on all pixel electrodes during the charge transport and, when there is charge trapping, small negative residual signals on all electrodes. If we wish to optimally obtain the event parameters, we should take all these signals into account. We wish to estimate x,y,z and E from the set of all electrode signals, {Si(t)}, including time dependence, using maximum-likelihood techniques[1]. To do this, we need to determine the probability of the electrode signals, given the event parameters {x, y, z, E}, i.e. Pr( {Si(t)} | {x, y, z, E} ). Thus we need to map the detector response of all pixels, {Si(t)}, for a large number of events with known x,y,z and E.In this paper we demonstrate the existence of the transient signals and residual signals and determine their magnitudes. They are typically 50-100 times smaller than the hit-pixel signals. We then describe development of an apparatus to measure the response of a 16-pixel semiconductor detector and show some preliminary results. We also discuss techniques for measuring the event parameters for individual gamma-ray interactions, a requirement for determining Pr( {Si(t)} | {x, y, z, E}).

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Otte, A. N.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Horan, D.; Mukherjee, R.; Smith, A.; Tajima, H.; Wagner, R. G.; Williams, D. A.

2008-12-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. Design goals are ten times better sensitivity, higher angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel diameter is reduced to the order of 0.05 deg, i.e. two to three times smaller than the pixel diameter of current Cherenkov telescope cameras. At these dimensions, photon detectors with smaller physical dimensions can be attractive alternatives to the classical photomultiplier tube (PMT). Furthermore, the operation of an experiment with the size of AGIS requires photon detectors that are among other things more reliable, more durable, and possibly higher efficiency photon detectors. Alternative photon detectors we are considering for AGIS include both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Here we present results from laboratory testing of MAPMTs and SiPMs along with results from the first incorporation of these devices into cameras on test bed Cherenkov telescopes.

A compact neutron scatter camera for field deployment

DOE PAGES

Goldsmith, John E. M.; Gerling, Mark D.; Brennan, James S.

2016-08-23

Here, we describe a very compact (0.9 m high, 0.4 m diameter, 40 kg) battery operable neutron scatter camera designed for field deployment. Unlike most other systems, the configuration of the sixteen liquid-scintillator detection cells are arranged to provide omnidirectional (4π) imaging with sensitivity comparable to a conventional two-plane system. Although designed primarily to operate as a neutron scatter camera for localizing energetic neutron sources, it also functions as a Compton camera for localizing gamma sources. In addition to describing the radionuclide source localization capabilities of this system, we demonstrate how it provides neutron spectra that can distinguish plutonium metalmore » from plutonium oxide sources, in addition to the easier task of distinguishing AmBe from fission sources.« less

Tomographic Small-Animal Imaging Using a High-Resolution Semiconductor Camera

PubMed Central

Kastis, GA; Wu, MC; Balzer, SJ; Wilson, DW; Furenlid, LR; Stevenson, G; Barber, HB; Barrett, HH; Woolfenden, JM; Kelly, P; Appleby, M

2015-01-01

We have developed a high-resolution, compact semiconductor camera for nuclear medicine applications. The modular unit has been used to obtain tomographic images of phantoms and mice. The system consists of a 64 x 64 CdZnTe detector array and a parallel-hole tungsten collimator mounted inside a 17 cm x 5.3 cm x 3.7 cm tungsten-aluminum housing. The detector is a 2.5 cm x 2.5 cm x 0.15 cm slab of CdZnTe connected to a 64 x 64 multiplexer readout via indium-bump bonding. The collimator is 7 mm thick, with a 0.38 mm pitch that matches the detector pixel pitch. We obtained a series of projections by rotating the object in front of the camera. The axis of rotation was vertical and about 1.5 cm away from the collimator face. Mouse holders were made out of acrylic plastic tubing to facilitate rotation and the administration of gas anesthetic. Acquisition times were varied from 60 sec to 90 sec per image for a total of 60 projections at an equal spacing of 6 degrees between projections. We present tomographic images of a line phantom and mouse bone scan and assess the properties of the system. The reconstructed images demonstrate spatial resolution on the order of 1–2 mm. PMID:26568676

Coded-aperture Compton camera for gamma-ray imaging

NASA Astrophysics Data System (ADS)

Farber, Aaron M.

This dissertation describes the development of a novel gamma-ray imaging system concept and presents results from Monte Carlo simulations of the new design. Current designs for large field-of-view gamma cameras suitable for homeland security applications implement either a coded aperture or a Compton scattering geometry to image a gamma-ray source. Both of these systems require large, expensive position-sensitive detectors in order to work effectively. By combining characteristics of both of these systems, a new design can be implemented that does not require such expensive detectors and that can be scaled down to a portable size. This new system has significant promise in homeland security, astronomy, botany and other fields, while future iterations may prove useful in medical imaging, other biological sciences and other areas, such as non-destructive testing. A proof-of-principle study of the new gamma-ray imaging system has been performed by Monte Carlo simulation. Various reconstruction methods have been explored and compared. General-Purpose Graphics-Processor-Unit (GPGPU) computation has also been incorporated. The resulting code is a primary design tool for exploring variables such as detector spacing, material selection and thickness and pixel geometry. The advancement of the system from a simple 1-dimensional simulation to a full 3-dimensional model is described. Methods of image reconstruction are discussed and results of simulations consisting of both a 4 x 4 and a 16 x 16 object space mesh have been presented. A discussion of the limitations and potential areas of further study is also presented.

Radiation imaging with a new scintillator and a CMOS camera

NASA Astrophysics Data System (ADS)

Kurosawa, S.; Shoji, Y.; Pejchal, J.; Yokota, Y.; Yoshikawa, A.

2014-07-01

A new imaging system consisting of a high-sensitivity complementary metal-oxide semiconductor (CMOS) sensor, a microscope and a new scintillator, Ce-doped Gd3(Al,Ga)5O12 (Ce:GAGG) grown by the Czochralski process, has been developed. The noise, the dark current and the sensitivity of the CMOS camera (ORCA-Flash4.0, Hamamatsu) was revised and compared to a conventional CMOS, whose sensitivity is at the same level as that of a charge coupled device (CCD) camera. Without the scintillator, this system had a good position resolution of 2.1 ± 0.4 μm and we succeeded in obtaining the alpha-ray images using 1-mm thick Ce:GAGG crystal. This system can be applied for example to high energy X-ray beam profile monitor, etc.

The Advanced Gamma-ray Imaging System (AGIS): Camera Electronics Designs

NASA Astrophysics Data System (ADS)

Tajima, H.; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Holder, J.; Horan, D.; Krawczynski, H.; Ong, R.; Swordy, S.; Wagner, R.; Williams, D.

2008-04-01

AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. These design concepts include systems based on multi-channel waveform sampling ASIC optimized for AGIS, a system based on IIT (image intensifier tube) for large channel (order of 1 million channels) readout as well as a multiplexed FADC system based on the current VERITAS readout design. Here we present trade-off in the studies of these design concepts.

The Advanced Gamma-ray Imaging System (AGIS): Camera Electronics Designs

NASA Astrophysics Data System (ADS)

Tajima, Hiroyasu; Buckley, J.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Holder, J.; Horan, D.; Krawczynski, H.; Ong, R.; Swordy, S.; Wagner, R.; Wakely, S.; Williams, D.; Camera Electronics Working Group; AGIS Collaboration

2008-03-01

AGIS, a next generation of atmospheric Cherenkov telescope arrays, aims to achieve a sensitivity level of a milliCrab for gamma-ray observations in in the energy band of 40 GeV to 100 TeV. Such improvement requires cost reduction of individual components with high reliability in order to equip the order of 100 telescopes necessary to achieve the sensitivity goal. We are exploring several design concepts to reduce the cost of camera electronics while improving their performance. These design concepts include systems based on multi-channel waveform sampling ASIC optimized for AGIS, a system based on IIT (image intensifier tube) for large channel (order of 1 million channels) readout as well as a multiplexed FADC system based on the current VERITAS readout design. Here we present trade-off studies of these design concepts.

Liver phantom for quality control and training in nuclear medicine

NASA Astrophysics Data System (ADS)

Lima Ferreira, Fernanda Carla; Souza, Divanizia do Nascimento

2011-10-01

In nuclear medicine, liver scintigraphy aims to verify organ function based on the radionuclide concentration in the liver and bile flow and is also used to detect tumors. Therefore it is necessary to perform quality control tests in the gamma camera before running the exam to prevent false results. Quality control tests of the gamma camera should thus be performed before running the exam to prevent false results. Such tests generally use radioactive material inside phantoms for evaluation of gamma camera parameters in quality control procedures. Phantoms can also be useful for training doctors and technicians in nuclear medicine procedures. The phantom proposed here has artifacts that simulate nodules; it may take on different quantities, locations and sizes and it may also be mounted without the introduction of nodules. Thus, its images may show hot or cold nodules or no nodules. The phantom consists of acrylic plates hollowed out in the centre, with the geometry of an adult liver. Images for analyses of simulated liver scintigraphy were obtained with the detector device at 5 cm from the anterior surface of the phantom. These simulations showed that this object is suitable for quality control in nuclear medicine because it was possible to visualize artifacts larger than 7.9 mm using a 256×256 matrix and 1000 kcpm. The phantom constructed in this work will also be useful for training practitioners and technicians in order to prevent patients from repeat testing caused by error during examinations.

Neutron and gamma-ray energy reconstruction for characterization of special nuclear material

DOE PAGES

Clarke, Shaun D.; Hamel, Michael C.; Di fulvio, Angela; ...

2017-06-30

Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for 252Cf and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-offlight kinematics can be used. With this system, energy spectra can also be obtained as a function of position.more » Finally, spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.« less

Thermal neutron detector and gamma-ray spectrometer utilizing a single material

DOEpatents

Stowe, Ashley; Burger, Arnold; Lukosi, Eric

2017-05-02

A combined thermal neutron detector and gamma-ray spectrometer system, including: a detection medium including a lithium chalcopyrite crystal operable for detecting thermal neutrons in a semiconductor mode and gamma-rays in a scintillator mode; and a photodetector coupled to the detection medium also operable for detecting the gamma rays. Optionally, the detection medium includes a .sup.6LiInSe.sub.2 crystal. Optionally, the detection medium comprises a compound formed by the process of: melting a Group III element; adding a Group I element to the melted Group III element at a rate that allows the Group I and Group III elements to react thereby providing a single phase I-III compound; and adding a Group VI element to the single phase I-III compound and heating; wherein the Group I element includes lithium.

Neutron and gamma-ray energy reconstruction for characterization of special nuclear material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clarke, Shaun D.; Hamel, Michael C.; Di fulvio, Angela

Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for 252Cf and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-offlight kinematics can be used. With this system, energy spectra can also be obtained as a function of position.more » Finally, spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.« less

Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

DOEpatents

Horn, Kevin M.

2013-07-09

A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1972-01-01

Significant accomplishments include development of a procedure to correct for the substantial differences of transistor delay time as measured with different instruments or with the same instrument at different frequencies; association of infrared response spectra of poor quality germanium gamma ray detectors with spectra of detectors fabricated from portions of a good crystal that had been degraded in known ways; and confirmation of the excellent quality and cosmetic appearance of ultrasonic bonds made with aluminum ribbon wire. Work is continuing on measurement of resistivity of semiconductor crystals; study of gold-doped silicon, development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.

Infrared Applications of Semiconductors II: Symposium Held in Boston, Massachusetts on December 1-4, 1997

DTIC Science & Technology

1997-12-01

James (Academic Press, San Diego, CA 1995) pp. 335-381. 2. J. R. Heffelfinger, D. L. Medlin, H. Yoon, H. Hermon and R. B. James, in Hard X - ray and...J. P. Cozzatti and J. P. Schomer, in Hard X - ray and Gamma-rav Detector Physics. Optics and Application, edited by R. B. Hoover and F. P. Doty (SPIE...resolution compared to the best previous instrumentation in hard x - ray and gamma ray astronomy. Previous work has shown the good imaging and

Apparatus for use in examining the lattice of a semiconductor wafer by X-ray diffraction

NASA Technical Reports Server (NTRS)

Parker, D. L.; Porter, W. A. (Inventor)

1978-01-01

An improved apparatus for examining the crystal lattice of a semiconductor wafer utilizing X-ray diffraction techniques was presented. The apparatus is employed in a method which includes the step of recording the image of a wafer supported in a bent configuration conforming to a compound curve, produced through the use of a vacuum chuck provided for an X-ray camera. The entire surface thereof is illuminated simultaneously by a beam of incident X-rays which are projected from a distant point-source and satisfy conditions of the Bragg Law for all points on the surface of the water.

A feasibility study of an integrated NIR/gamma/visible imaging system for endoscopic sentinel lymph node mapping.

PubMed

Kang, Han Gyu; Lee, Ho-Young; Kim, Kyeong Min; Song, Seong-Hyun; Hong, Gun Chul; Hong, Seong Jong

2017-01-01

The aim of this study is to integrate NIR, gamma, and visible imaging tools into a single endoscopic system to overcome the limitation of NIR using gamma imaging and to demonstrate the feasibility of endoscopic NIR/gamma/visible fusion imaging for sentinel lymph node (SLN) mapping with a small animal. The endoscopic NIR/gamma/visible imaging system consists of a tungsten pinhole collimator, a plastic focusing lens, a BGO crystal (11 × 11 × 2 mm 3 ), a fiber-optic taper (front = 11 × 11 mm 2 , end = 4 × 4 mm 2 ), a 122-cm long endoscopic fiber bundle, an NIR emission filter, a relay lens, and a CCD camera. A custom-made Derenzo-like phantom filled with a mixture of 99m Tc and indocyanine green (ICG) was used to assess the spatial resolution of the NIR and gamma images. The ICG fluorophore was excited using a light-emitting diode (LED) with an excitation filter (723-758 nm), and the emitted fluorescence photons were detected with an emission filter (780-820 nm) for a duration of 100 ms. Subsequently, the 99m Tc distribution in the phantom was imaged for 3 min. The feasibility of in vivo SLN mapping with a mouse was investigated by injecting a mixture of 99m Tc-antimony sulfur colloid (12 MBq) and ICG (0.1 mL) into the right paw of the mouse (C57/B6) subcutaneously. After one hour, NIR, gamma, and visible images were acquired sequentially. Subsequently, the dissected SLN was imaged in the same way as the in vivo SLN mapping. The NIR, gamma, and visible images of the Derenzo-like phantom can be obtained with the proposed endoscopic imaging system. The NIR/gamma/visible fusion image of the SLN showed a good correlation among the NIR, gamma, and visible images both for the in vivo and ex vivo imaging. We demonstrated the feasibility of the integrated NIR/gamma/visible imaging system using a single endoscopic fiber bundle. In future, we plan to investigate miniaturization of the endoscope head and simultaneous NIR/gamma/visible imaging with dichroic mirrors and three CCD cameras. © 2016 American Association of Physicists in Medicine.

MeV gamma-ray observation with a well-defined point spread function based on electron tracking

NASA Astrophysics Data System (ADS)

Takada, A.; Tanimori, T.; Kubo, H.; Mizumoto, T.; Mizumura, Y.; Komura, S.; Kishimoto, T.; Takemura, T.; Yoshikawa, K.; Nakamasu, Y.; Matsuoka, Y.; Oda, M.; Miyamoto, S.; Sonoda, S.; Tomono, D.; Miuchi, K.; Kurosawa, S.; Sawano, T.

2016-07-01

The field of MeV gamma-ray astronomy has not opened up until recently owing to imaging difficulties. Compton telescopes and coded-aperture imaging cameras are used as conventional MeV gamma-ray telescopes; however their observations are obstructed by huge background, leading to uncertainty of the point spread function (PSF). Conventional MeV gamma-ray telescopes imaging utilize optimizing algorithms such as the ML-EM method, making it difficult to define the correct PSF, which is the uncertainty of a gamma-ray image on the celestial sphere. Recently, we have defined and evaluated the PSF of an electron-tracking Compton camera (ETCC) and a conventional Compton telescope, and thereby obtained an important result: The PSF strongly depends on the precision of the recoil direction of electron (scatter plane deviation, SPD) and is not equal to the angular resolution measure (ARM). Now, we are constructing a 30 cm-cubic ETCC for a second balloon experiment, Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment: SMILE-II. The current ETCC has an effective area of 1 cm2 at 300 keV, a PSF of 10° at FWHM for 662 keV, and a large field of view of 3 sr. We will upgrade this ETCC to have an effective area of several cm2 and a PSF of 5° using a CF4-based gas. Using the upgraded ETCC, our observation plan for SMILE-II is to map of the electron-positron annihilation line and the 1.8 MeV line from 26Al. In this paper, we will report on the current performance of the ETCC and on our observation plan.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ginsz, M.; Duchene, G.; Didierjean, F.

The state-of-the art gamma-ray spectrometers such as AGATA and GRETA are using position sensitive multi-segmented HPGe crystals. Pulse-shape analysis (PSA) allows to retrieve the localisation of the gamma interactions and to perform gamma-ray tracking within germanium. The precision of the localisation depends on the quality of the pulse-shape database used for comparison. The IPHC laboratory developed a new fast scanning table allowing to measure experimental pulse shapes in the whole volume of any crystal. The results of the scan of an AGATA 36-fold segmented tapered coaxial detector are shown here, 48580 experimental pulse shapes are extracted within 2 weeks ofmore » scanning. These data will contribute to AGATA PSA performances, but have also applications for gamma cameras or Compton-suppressed detectors. (authors)« less

Background simulations of the wide-field coded-mask camera for X-/Gamma-ray of the French-Chinese mission SVOM

NASA Astrophysics Data System (ADS)

Godet, Olivier; Barret, Didier; Paul, Jacques; Sizun, Patrick; Mandrou, Pierre; Cordier, Bertrand

SVOM (Space Variable Object Monitor) is a French-Chinese mission dedicated to the study of high-redshift GRBs, which is expected to be launched in 2012. The anti-Sun pointing strategy of SVOM along with a strong and integrated ground segment consisting of two wide-field robotic telescopes covering the near-IR and optical will optimise the ground-based GRB follow-ups by the largest telescopes and thus the measurements of spectroscopic redshifts. The central instrument of the science payload will be an innovative wide-field coded-mask camera for X- /Gamma-rays (4-250 keV) responsible for triggering and localising GRBs with an accuracy better than 10 arc-minutes. Such an instrument will be background-dominated so it is essential to estimate the background level expected once in orbit during the early phase of the instrument design in order to ensure good science performance. We present our Monte-Carlo simulator enabling us to compute the background spectrum taking into account the mass model of the camera and the main components of the space environment encountered in orbit by the satellite. From that computation, we show that the current design of the camera CXG will be more sensitive to high-redshift GRBs than the Swift-BAT thanks to its low-energy threshold of 4 keV.

Semiconductor quantum dot scintillation under gamma-ray irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Letant, S E; Wang, T

2006-08-23

We recently demonstrated the ability of semiconductor quantum dots to convert alpha radiation into visible photons. In this letter, we report on the scintillation of quantum dots under gamma-ray irradiation, and compare the energy resolution of the 59 keV line of Americium 241 obtained with our quantum dot-glass nanocomposite material to that of a standard sodium iodide scintillator. A factor 2 improvement is demonstrated experimentally and interpreted theoretically using a combination of energy-loss and photon transport models. These results demonstrate the potential of quantum dots for room-temperature gamma-ray detection, which has applications in medical imaging, environmental monitoring, as well asmore » security and defense. Present technology in gamma radiation detection suffers from flexibility and scalability issues. For example, bulk Germanium provides fine energy resolution (0.2% energy resolution at 1.33 MeV) but requires operation at liquid nitrogen temperature. On the other hand, Cadmium-Zinc-Telluride is a good room temperature detector ( 1% at 662 keV) but the size of the crystals that can be grown is limited to a few centimeters in each direction. Finally, the most commonly used scintillator, Sodium Iodide (NaI), can be grown as large crystals but suffers from a lack of energy resolution (7% energy resolution at 662 keV). Recent advancements in nanotechnology6-10 have provided the possibility of controlling materials synthesis at the molecular level. Both morphology and chemical composition can now be manipulated, leading to radically new material properties due to a combination of quantum confinement and surface to volume ratio effects. One of the main consequences of reducing the size of semiconductors down to nanometer dimensions is to increase the energy band gap, leading to visible luminescence, which suggests that these materials could be used as scintillators. The visible band gap of quantum dots would also ensure both efficient photon counting (better coupling with photomultipliers optimized for the visible region), and high photon output (smaller individual photon energy results in more photons produced) at room temperature, which is essential for effective Poisson counting (the energy resolution {Delta}E/E is inversely proportional to the square root of the number of photons collected).« less

Performance verification of the FlashCam prototype camera for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Werner, F.; Bauer, C.; Bernhard, S.; Capasso, M.; Diebold, S.; Eisenkolb, F.; Eschbach, S.; Florin, D.; Föhr, C.; Funk, S.; Gadola, A.; Garrecht, F.; Hermann, G.; Jung, I.; Kalekin, O.; Kalkuhl, C.; Kasperek, J.; Kihm, T.; Lahmann, R.; Marszalek, A.; Pfeifer, M.; Principe, G.; Pühlhofer, G.; Pürckhauer, S.; Rajda, P. J.; Reimer, O.; Santangelo, A.; Schanz, T.; Schwab, T.; Steiner, S.; Straumann, U.; Tenzer, C.; Vollhardt, A.; Wolf, D.; Zietara, K.; CTA Consortium

2017-12-01

The Cherenkov Telescope Array (CTA) is a future gamma-ray observatory that is planned to significantly improve upon the sensitivity and precision of the current generation of Cherenkov telescopes. The observatory will consist of several dozens of telescopes with different sizes and equipped with different types of cameras. Of these, the FlashCam camera system is the first to implement a fully digital signal processing chain which allows for a traceable, configurable trigger scheme and flexible signal reconstruction. As of autumn 2016, a prototype FlashCam camera for the medium-sized telescopes of CTA nears completion. First results of the ongoing system tests demonstrate that the signal chain and the readout system surpass CTA requirements. The stability of the system is shown using long-term temperature cycling.

The effects of gamma irradiation on electrical characteristics of Zn/ZnO/n-Si/Au-Sb structure

NASA Astrophysics Data System (ADS)

Salari, M. Abdolahpour; Güzeldir, B.; Saǧlam, M.

2018-02-01

In this research, we have investigated the electrical characteristics of Zn/ZnO/n-Si/Au-Sb structure before and after 60Co gamma (γ)-ray source irradiation with the total dose range of 0-500 kGy at room temperature. Electrical measurements of this structure have been performed using current-voltage (I-V) and capacitance-voltage (C-V) techniques. Experimental results show that the values of the ideality factor obtained from I-V measurements increased and the values of the barrier height obtained from reverse-bias C-V measurements decreased after gamma-irradiation. The results show that the main effect of the radiation is the generation of laterally inhomogeneous defects near the semiconductor surface.

Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam

NASA Astrophysics Data System (ADS)

Hueso-González, F.; Golnik, C.; Berthel, M.; Dreyer, A.; Enghardt, W.; Fiedler, F.; Heidel, K.; Kormoll, T.; Rohling, H.; Schöne, S.; Schwengner, R.; Wagner, A.; Pausch, G.

2014-05-01

In the context of ion beam therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density map, which is correlated with the dose distribution. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a Compton camera setup is being developed consisting of two scatter planes: two CdZnTe (CZT) cross strip detectors, and an absorber consisting of one Lu2SiO5 (LSO) block detector. The data acquisition is based on VME electronics and handled by software developed on the ROOT framework. The setup has been tested at the linear electron accelerator ELBE at HZDR, which is used in this experiment to produce bunched bremsstrahlung photons with up to 12.5 MeV energy and a repetition rate of 13 MHz. Their spectrum has similarities with the shape expected from prompt gamma rays in the clinical environment, and the flux is also bunched with the accelerator frequency. The charge sharing effect of the CZT detector is studied qualitatively for different energy ranges. The LSO detector pixel discrimination resolution is analyzed and it shows a trend to improve for high energy depositions. The time correlation between the pulsed prompt photons and the measured detector signals, to be used for background suppression, exhibits a time resolution of 3 ns FWHM for the CZT detector and of 2 ns for the LSO detector. A time walk correction and pixel-wise calibration is applied for the LSO detector, whose resolution improves up to 630 ps. In conclusion, the detector setup is suitable for time-resolved background suppression in pulsed clinical particle accelerators. Ongoing tasks are the quantitative comparison with simulations and the test of imaging algorithms. Experiments at proton accelerators have also been performed and are currently under analysis.

Practical target location and accuracy indicator in digital close range photogrammetry using consumer grade cameras

NASA Astrophysics Data System (ADS)

Moriya, Gentaro; Chikatsu, Hirofumi

2011-07-01

Recently, pixel numbers and functions of consumer grade digital camera are amazingly increasing by modern semiconductor and digital technology, and there are many low-priced consumer grade digital cameras which have more than 10 mega pixels on the market in Japan. In these circumstances, digital photogrammetry using consumer grade cameras is enormously expected in various application fields. There is a large body of literature on calibration of consumer grade digital cameras and circular target location. Target location with subpixel accuracy had been investigated as a star tracker issue, and many target location algorithms have been carried out. It is widely accepted that the least squares models with ellipse fitting is the most accurate algorithm. However, there are still problems for efficient digital close range photogrammetry. These problems are reconfirmation of the target location algorithms with subpixel accuracy for consumer grade digital cameras, relationship between number of edge points along target boundary and accuracy, and an indicator for estimating the accuracy of normal digital close range photogrammetry using consumer grade cameras. With this motive, an empirical testing of several algorithms for target location with subpixel accuracy and an indicator for estimating the accuracy are investigated in this paper using real data which were acquired indoors using 7 consumer grade digital cameras which have 7.2 mega pixels to 14.7 mega pixels.

Two-modality γ detection of blood volume by camera imaging and nonimaging stethoscope for kinetic studies of cardiovascular control in nuclear medicine

NASA Astrophysics Data System (ADS)

Eclancher, Bernard; Chambron, Jacques; Dumitresco, Barbu; Karman, Miklos; Pszota, Agnes; Simon, Atilla; Didon-Poncelet, Anna; Demangeat, Jean

2002-04-01

The quantification of rapid hemodynamic reactions to wide and slow breathing movements has been performed, by two modalities (gamma) -left ventriculography of 99mTc-labeled blood volume, in anterior oblique incidence on standing and even exercising healthy volunteers and cardiac patients. A highly sensitive stethoscope delivered whole (gamma) -counts acquired at 30 msec intervals in a square field of view including the left ventricle, in a one dimensional low resolution imaging mode for beat to beat analysis. A planar 2D (gamma) -camera imaging of the same cardiac area was then performed without cardiac gating for alternate acquisitions during deep inspiration and deep expiration, completed by a 3D MRI assessment of the stethoscope detection field. Young healthy volunteers displayed wide variations of diastolic times and stroke volumes, as a result of enhanced baroreflex control, together with +/- 16% variations of the stethoscope's background blood volume counts. Any of the components of these responses were shifted, abolished or even inverted as a result of either obesity, hypertension, aging or cardiac pathologies. The assessment of breathing control of the cardiovascular system by the beat to beat (gamma) -ventriculography combined with nuclear 2D and 3D MRI imaging is a kinetic method allowing the detection of functional anomalies in still ambulatory patients.

Determination of in vivo behavior of mitomycin C-loaded o/w soybean oil microemulsion and mitomycin C solution via gamma camera imaging.

PubMed

Kotmakçı, Mustafa; Kantarcı, Gülten; Aşıkoğlu, Makbule; Ozkılıç, Hayal; Ertan, Gökhan

2013-09-01

In this study, a microemulsion system was evaluated for delivery of mitomycin C (MMC). To track the distribution of the formulated drug after intravenous administration, radiochemical labeling and gamma scintigraphy imaging were used. The aim was to evaluate a microemulsion system for intravenous delivery of MMC and to compare its in vivo behavior with that of the MMC solution. For microemulsion formulation, soybean oil was used as the oil phase. Lecithin and Tween 80 were surfactants and ethanol was the cosurfactant. To understand the whole body localization of MMC-loaded microemulsion, MMC was labeled with radioactive technetium and gamma scintigraphy was applied for visualization of drug distribution. Radioactivity in the bladder 30 minutes after injection of the MMC solution was observed, according to static gamma camera images. This shows that urinary excretion of the latter starts very soon. On the other hand, no radioactivity appeared in the urinary bladder during the 90 minutes following the administration of MMC-loaded microemulsion. The unabated radioactivity in the liver during the experiment shows that the localization of microemulsion formulation in the liver is stable. In the light of the foregoing, it is suggested that this microemulsion formulation may be an appropriate carrier system for anticancer agents by intravenous delivery in hepatic cancer chemotherapy.

The soft gamma-ray detector (SGD) onboard ASTRO-H

NASA Astrophysics Data System (ADS)

Watanabe, Shin; Tajima, Hiroyasu; Fukazawa, Yasushi; Blandford, Roger; Enoto, Teruaki; Goldwurm, Andrea; Hagino, Kouichi; Hayashi, Katsuhiro; Ichinohe, Yuto; Kataoka, Jun; Katsuta, Junichiro; Kitaguchi, Takao; Kokubun, Motohide; Laurent, Philippe; Lebrun, François; Limousin, Olivier; Madejski, Grzegorz M.; Makishima, Kazuo; Mizuno, Tsunefumi; Mori, Kunishiro; Nakamori, Takeshi; Nakano, Toshio; Nakazawa, Kazuhiro; Noda, Hirofumu; Odaka, Hirokazu; Ohno, Masanori; Ohta, Masayuki; Saito, Shinya; Sato, Goro; Sato, Rie; Takeda, Shin'ichiro; Takahashi, Hiromitsu; Takahashi, Tadayuki; Tanaka, Takaaki; Tanaka, Yasuyuki; Terada, Yukikatsu; Uchiyama, Hideki; Uchiyama, Yasunobu; Yamaoka, Kazutaka; Yatsu, Yoichi; Yonetoku, Daisuke; Yuasa, Takayuki

2016-07-01

The Soft Gamma-ray Detector (SGD) is one of science instruments onboard ASTRO-H (Hitomi) and features a wide energy band of 60{600 keV with low backgrounds. SGD is an instrument with a novel concept of "Narrow field-of-view" Compton camera where Compton kinematics is utilized to reject backgrounds which are inconsistent with the field-of-view defined by the active shield. After several years of developments, the flight hardware was fabricated and subjected to subsystem tests and satellite system tests. After a successful ASTRO-H (Hitomi) launch on February 17, 2016 and a critical phase operation of satellite and SGD in-orbit commissioning, the SGD operation was moved to the nominal observation mode on March 24, 2016. The Compton cameras and BGO-APD shields of SGD worked properly as designed. On March 25, 2016, the Crab nebula observation was performed, and, the observation data was successfully obtained.

Inauguration and first light of the GCT-M prototype for the Cherenkov telescope array

NASA Astrophysics Data System (ADS)

Watson, J. J.; De Franco, A.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jegouzo, I.; Jogler, T.; Kraus, M.; Lapington, J. S.; Laporte, P.; Lefaucheur, J.; Markoff, S.; Melse, T.; Mohrmann, L.; Molyneux, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Vink, J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

2017-01-01

The Gamma-ray Cherenkov Telescope (GCT) is a candidate for the Small Size Telescopes (SSTs) of the Cherenkov Telescope Array (CTA). Its purpose is to extend the sensitivity of CTA to gamma-ray energies reaching 300 TeV. Its dual-mirror optical design and curved focal plane enables the use of a compact camera of 0.4 m diameter, while achieving a field of view of above 8 degrees. Through the use of the digitising TARGET ASICs, the Cherenkov flash is sampled once per nanosecond contin-uously and then digitised when triggering conditions are met within the analogue outputs of the photosensors. Entire waveforms (typically covering 96 ns) for all 2048 pixels are then stored for analysis, allowing for a broad spectrum of investigations to be performed on the data. Two prototypes of the GCT camera are under development, with differing photosensors: Multi-Anode Photomultipliers (MAPMs) and Silicon Photomultipliers (SiPMs). During November 2015, the GCT MAPM (GCT-M) prototype camera was integrated onto the GCT structure at the Observatoire de Paris-Meudon, where it observed the first Cherenkov light detected by a prototype instrument for CTA.

Nuclear Science Symposium, 23rd, Scintillation and Semiconductor Counter Symposium, 15th, and Nuclear Power Systems Symposium, 8th, New Orleans, La., October 20-22, 1976, Proceedings

NASA Technical Reports Server (NTRS)

Wagner, L. J.

1977-01-01

The volume includes papers on semiconductor radiation detectors of various types, components of radiation detection and dosimetric systems, digital and microprocessor equipment in nuclear industry and science, and a wide variety of applications of nuclear radiation detectors. Semiconductor detectors of X-rays, gamma radiation, heavy ions, neutrons, and other nuclear particles, plastic scintillator arrays, drift chambers, spark wire chambers, and radiation dosimeter systems are reported on. Digital and analog conversion systems, digital data and control systems, microprocessors, and their uses in scientific research and nuclear power plants are discussed. Large-area imaging and biomedical nucleonic instrumentation, nuclear power plant safeguards, reactor instrumentation, nuclear power plant instrumentation, space instrumentation, and environmental instrumentation are dealt with. Individual items are announced in this issue.

Characterization and commissioning of the SST-1M camera for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Bilnik, W.; Błocki, J.; Bogacz, L.; Borkowski, J.; Bulik, T.; Cadoux, F.; Christov, A.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Heller, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Kasperek, J.; Lalik, K.; Lyard, E.; Mach, E.; Mandat, D.; Marszałek, A.; Medina Miranda, L. D.; Michałowski, J.; Moderski, R.; Montaruli, T.; Neronov, A.; Niemiec, J.; Ostrowski, M.; Paśko, P.; Pech, M.; Porcelli, A.; Prandini, E.; Rajda, P.; Rameez, M.; Schioppa, E., Jr.; Schovanek, P.; Seweryn, K.; Skowron, K.; Sliusar, V.; Sowiński, M.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Toscano, S.; Troyano Pujadas, I.; Walter, R.; Wiȩcek, M.; Zagdański, A.; Ziȩtara, K.; Żychowski, P.

2017-02-01

The Cherenkov Telescope Array (CTA), the next generation very high energy gamma-rays observatory, will consist of three types of telescopes: large (LST), medium (MST) and small (SST) size telescopes. The SSTs are dedicated to the observation of gamma-rays with energy between a few TeV and a few hundreds of TeV. The SST array is expected to have 70 telescopes of different designs. The single-mirror small size telescope (SST-1 M) is one of the proposed telescope designs under consideration for the SST array. It will be equipped with a 4 m diameter segmented mirror dish and with an innovative camera based on silicon photomultipliers (SiPMs). The challenge is not only to build a telescope with exceptional performance but to do it foreseeing its mass production. To address both of these challenges, the camera adopts innovative solutions both for the optical system and readout. The Photo-Detection Plane (PDP) of the camera is composed of 1296 pixels, each made of a hollow, hexagonal light guide coupled to a hexagonal SiPM designed by the University of Geneva and Hamamatsu. As no commercial ASIC would satisfy the CTA requirements when coupled to such a large sensor, dedicated preamplifier electronics have been designed. The readout electronics also use an innovative approach in gamma-ray astronomy by adopting a fully digital approach. All signals coming from the PDP are digitized in a 250 MHz Fast ADC and stored in ring buffers waiting for a trigger decision to send them to the pre-processing server where calibration and higher level triggers will decide whether the data are stored. The latest generation of FPGAs is used to achieve high data rates and also to exploit all the flexibility of the system. As an example each event can be flagged according to its trigger pattern. All of these features have been demonstrated in laboratory measurements on realistic elements and the results of these measurements will be presented in this contribution.

SU-C-9A-02: Structured Noise Index as An Automated Quality Control for Nuclear Medicine: A Two Year Experience

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, J; Christianson, O; Samei, E

Purpose: Flood-field uniformity evaluation is an essential element in the assessment of nuclear medicine (NM) gamma cameras. It serves as the central element of the quality control (QC) program, acquired and analyzed on a daily basis prior to clinical imaging. Uniformity images are traditionally analyzed using pixel value-based metrics which often fail to capture subtle structure and patterns caused by changes in gamma camera performance requiring additional visual inspection which is subjective and time demanding. The goal of this project was to develop and implement a robust QC metrology for NM that is effective in identifying non-uniformity issues, reporting issuesmore » in a timely manner for efficient correction prior to clinical involvement, all incorporated into an automated effortless workflow, and to characterize the program over a two year period. Methods: A new quantitative uniformity analysis metric was developed based on 2D noise power spectrum metrology and confirmed based on expert observer visual analysis. The metric, termed Structured Noise Index (SNI) was then integrated into an automated program to analyze, archive, and report on daily NM QC uniformity images. The effectiveness of the program was evaluated over a period of 2 years. Results: The SNI metric successfully identified visually apparent non-uniformities overlooked by the pixel valuebased analysis methods. Implementation of the program has resulted in nonuniformity identification in about 12% of daily flood images. In addition, due to the vigilance of staff response, the percentage of days exceeding trigger value shows a decline over time. Conclusion: The SNI provides a robust quantification of the NM performance of gamma camera uniformity. It operates seamlessly across a fleet of multiple camera models. The automated process provides effective workflow within the NM spectra between physicist, technologist, and clinical engineer. The reliability of this process has made it the preferred platform for NM uniformity analysis.« less

Electron-tracking Compton gamma-ray camera for small animal and phantom imaging

NASA Astrophysics Data System (ADS)

Kabuki, Shigeto; Kimura, Hiroyuki; Amano, Hiroo; Nakamoto, Yuji; Kubo, Hidetoshi; Miuchi, Kentaro; Kurosawa, Shunsuke; Takahashi, Michiaki; Kawashima, Hidekazu; Ueda, Masashi; Okada, Tomohisa; Kubo, Atsushi; Kunieda, Etuso; Nakahara, Tadaki; Kohara, Ryota; Miyazaki, Osamu; Nakazawa, Tetsuo; Shirahata, Takashi; Yamamoto, Etsuji; Ogawa, Koichi; Togashi, Kaori; Saji, Hideo; Tanimori, Toru

2010-11-01

We have developed an electron-tracking Compton camera (ETCC) for medical use. Our ETCC has a wide energy dynamic range (200-1300 keV) and wide field of view (3 sr), and thus has potential for advanced medical use. To evaluate the ETCC, we imaged the head (brain) and bladder of mice that had been administered with F-18-FDG. We also imaged the head and thyroid gland of mice using double tracers of F-18-FDG and I-131 ions.

Thermal Neutron Tomography for Cultural Heritage at INR

NASA Astrophysics Data System (ADS)

Dinca, Marin; Mandescu, Dragos

The neutron and gamma imaging facility placed at the tangential channel of the TRIGA-ACPR from INR was used for tomography investigations on a test object with good results and shortly followed its involvement for tomography investigations on prehistoric statues of clay from the Arges County Museum. This activity was performed in connection with a research contract with IAEA with title ;The neutron and gamma imaging method combined with neutron-based analytical methods for cultural heritage research;, in the frame of a current CRP, that helps curators to reveal the internal structure and composition of the objects. The detector system has been developed based on two interchangeable scintillators, one for thermal neutrons and the other one for gamma radiations, a mirror of float glass coated with aluminum and two interchangeable CCD cameras. Experiments of tomography imaging for two prehistoric statues of clay with CCD STARLIGHT XPRESS SXV-H9 camera with XD-4 type image intensifier are presented in this paper. The tomography reconstructions with Octopus software have shown the potential of good results even for 100 projections/1800. This was a good opportunity for the dissemination of the investigation methods based on neutrons for cultural heritage and beyond this area.

Effect of different thickness of material filter on Tc-99m spectra and performance parameters of gamma camera

NASA Astrophysics Data System (ADS)

Nazifah, A.; Norhanna, S.; Shah, S. I.; Zakaria, A.

2014-11-01

This study aimed to investigate the effects of material filter technique on Tc-99m spectra and performance parameters of Philip ADAC forte dual head gamma camera. Thickness of material filter was selected on the basis of percentage attenuation of various gamma ray energies by different thicknesses of zinc material. A cylindrical source tank of NEMA single photon emission computed tomography (SPECT) Triple Line Source Phantom filled with water and Tc-99m radionuclide injected was used for spectra, uniformity and sensitivity measurements. Vinyl plastic tube was used as a line source for spatial resolution. Images for uniformity were reconstructed by filtered back projection method. Butterworth filter of order 5 and cut off frequency 0.35 cycles/cm was selected. Chang's attenuation correction method was applied by selecting 0.13/cm linear attenuation coefficient. Count rate was decreased with material filter from the compton region of Tc-99m energy spectrum, also from the photopeak region. Spatial resolution was improved. However, uniformity of tomographic image was equivocal, and system volume sensitivity was reduced by material filter. Material filter improved system's spatial resolution. Therefore, the technique may be used for phantom studies to improve the image quality.

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, Robert G.; AGIS Photodetector Group; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Horan, D.; Mukherjee, R.; Tajima, H.; Williams, D.

2008-03-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. It is being designed to achieve a significant improvement in sensitivity compared to current Imaging Air Cherenkov Telescope (IACT) Arrays. One of the main requirements in order that AGIS fulfill this goal will be to achieve higher angular resolution than current IACTs. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel size is reduced to less than 0.05 deg, i.e. two to three times smaller than the pixel size of current IACT cameras. With finer pixelation and the plan to deploy on the order of 100 telescopes in the AGIS array, the channel count will exceed 1,000,000 imaging pixels. High uniformity and long mean time-to-failure will be important aspects of a successful photodetector technology choice. Here we present alternatives being considered for AGIS, including both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Results from laboratory testing of MAPMTs and SiPMs are presented along with results from the first incorporation of these devices in cameras on test bed Cherenkov telescopes.

Cross sections for production of the 15.10 MeV and other astrophysically significant gamma-ray lines through excitation and spallation of sup 12 C and sup 16 O with protons

NASA Technical Reports Server (NTRS)

Lang, F. L.; Werntz, C. W.; Crannell, C. J.; Trombka, J. I.; Chang, C. C.

1986-01-01

The ratio of the flux of 15.10-MeV gamma rays to the flux of 4.438-MeV gamma rays resulting from excitation of the corresponding states in C-12 as a sensitive measure of the spectrum of the exciting particles produced in solar flares and other cosmic sources. These gamma rays are produced predominantly by interactions with C-12 and O-16, both of which are relatively abundant in the solar photosphere. Gamma ray production cross sections for proton interactions have been reported previously for all important channels except for the production of 15.10-MeV gamma rays from O-16. The first reported measurement of the 15.10-MeV gamma ray production cross section from p + O-16 is presented here. The University of Maryland cyclotron was employed to produce 40-, 65-, and 86-MeV protons which interacted with CH2 and BeO targets. The resultant gamma ray spectra were measured with a high-purity germanium semiconductor detector at 70, 90, 110, 125, and 140 degrees relative to the direction of the incident beam for each proton energy. Other gamma ray lines resulting from direct excitation and spallation reactions with C-12 and 0-16 were observed as well, and their gamma ray production cross sections described.

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

PubMed

Perez-Garcia, H; Barquero, R

The correct determination and delineation of tumor/organ size is crucial in 2-D imaging in 131 I therapy. These images are usually obtained using a system composed of a Gamma camera and high-energy collimator, although the system can produce artifacts in the image. This article analyses these artifacts and describes a correction filter that can eliminate those collimator artifacts. Using free software, ImageJ, a central profile in the image is obtained and analyzed. Two components can be seen in the fluctuation of the profile: one associated with the stochastic nature of the radiation, plus electronic noise and the other periodically across the position in space due to the collimator. These frequencies are analytically obtained and compared with the frequencies in the Fourier transform of the profile. A specially developed filter removes the artifacts in the 2D Fourier transform of the DICOM image. This filter is tested using a 15-cm-diameter Petri dish with 131 I radioactive water (big object size) image, a 131 I clinical pill (small object size) image, and an image of the remainder of the lesion of two patients treated with 3.7GBq (100mCi), and 4.44GBq (120mCi) of 131 I, respectively, after thyroidectomy. The artifact is due to the hexagonal periodic structure of the collimator. The use of the filter on large-sized images reduces the fluctuation by 5.8-3.5%. In small-sized images, the FWHM can be determined in the filtered image, while this is impossible in the unfiltered image. The definition of tumor boundary and the visualization of the activity distribution inside patient lesions improve drastically when the filter is applied to the corresponding images obtained with HE gamma camera. The HURRA filter removes the artifact of high-energy collimator artifacts in planar images obtained with a Gamma camera without reducing the image resolution. It can be applied in any study of patient quantification because the number of counts remains invariant. The filter makes possible the definition and delimitation of small uptakes, such as those presented in treatments with 131 I. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Performance and Calibration of H2RG Detectors and SIDECAR ASICs for the RATIR Camera

NASA Technical Reports Server (NTRS)

Fox, Ori D.; Kutyrev, Alexander S.; Rapchun, David A.; Klein, Christopher R.; Butler, Nathaniel R.; Bloom, Josh; de Diego, Jos A.; Simn Farah, Alejandro D.; Gehrels, Neil A.; Georgiev, Leonid;

Nuclear medicine imaging system

DOEpatents

Bennett, G.W.; Brill, A.B.; Bizais, Y.J.C.; Rowe, R.W.; Zubal, I.G.

1983-03-11

It is an object of this invention to provide a nuclear imaging system having the versatility to do positron annihilation studies, rotating single or opposed camera gamma emission studies, and orthogonal gamma emission studies. It is a further object of this invention to provide an imaging system having the capability for orthogonal dual multipinhole tomography. It is another object of this invention to provide a nuclear imaging system in which all available energy data, as well as patient physiological data, are acquired simultaneously in list mode.

Optical photometric monitoring of gamma -ray loud blazars. II. Observations from November 1995 to June 1996

NASA Astrophysics Data System (ADS)

Raiteri, C. M.; Ghisellini, G.; Villata, M.; de Francesco, G.; Lanteri, L.; Chiaberge, M.; Peila, A.; Antico, G.

1998-02-01

New data from the optical monitoring of gamma -ray loud blazars at the Torino Astronomical Observatory are presented. Observations have been taken in the Johnson's B, V, and Cousins' R bands with the 1.05m REOSC telescope equipped with a 1242x1152 pixel CCD camera. Many of the 22 monitored sources presented here show noticeable magnitude variations. Periods corresponding to pointings of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) satellite are indicated on the light curves. The comparison of our data with those taken by CGRO in the gamma -ray band will contribute to better understand the mechanism of the gamma -ray emission. We finally show intranight light curves of 3C 66A and OJ 287, where microvariability was detected. Tables 2--21 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

The Use of Gamma-Ray Imaging to Improve Portal Monitor Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziock, Klaus-Peter; Collins, Jeff; Fabris, Lorenzo

2008-01-01

We have constructed a prototype, rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. Our Roadside Tracker uses automated target acquisition and tracking (TAT) software to identify and track vehicles in visible light images. The field of view of the visible camera overlaps with and is calibrated to that of a one-dimensional gamma-ray imager. The TAT code passes information on when vehicles enter and exit the system field of view and when they cross gamma-ray pixel boundaries. Based on this in-formation, the gamma-ray imager "harvests"more » the gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. In this fashion we are able to generate vehicle-specific radiation signatures and avoid source confusion problems that plague nonimaging approaches to the same problem.« less

A balloon-borne high-resolution spectrometer for observations of gamma-ray emission from solar flares

NASA Technical Reports Server (NTRS)

Crannell, C. J.; Starr, R.; Stottlemyre, A. R.; Trombka, J. I.

1984-01-01

The design, development, and balloon-flight verification of a payload for observations of gamma-ray emission from solar flares are reported. The payload incorporates a high-purity germanium semiconductor detector, standard NIM and CAMAC electronics modules, a thermally stabilized pressure housing, and regulated battery power supplies. The flight system is supported on the ground with interactive data-handling equipment comprised of similar electronics hardware. The modularity and flexibility of the payload, together with the resolution and stability obtained throughout a 30-hour flight, make it readily adaptable for high-sensitivity, long-duration balloon fight applications.

Recent Improvement of Measurement Instrumentation to Supervise Nuclear Operations and to Contribute Input Data to 3D Simulation Code - 13289

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahe, Charly; Chabal, Caroline

2013-07-01

The CEA has developed many compact characterization tools to follow sensitive operations in a nuclear environment. Usually, these devices are made to carry out radiological inventories, to prepare nuclear interventions or to supervise some special operations. These in situ measurement techniques mainly take place at different stages of clean-up operations and decommissioning projects, but they are also in use to supervise sensitive operations when the nuclear plant is still operating. In addition to this, such tools are often associated with robots to access very highly radioactive areas, and thus can be used in accident situations. Last but not least, themore » radiological data collected can be entered in 3D calculation codes used to simulate the doses absorbed by workers in real time during operations in a nuclear environment. Faced with these ever-greater needs, nuclear measurement instrumentation always has to involve on-going improvement processes. Firstly, this paper will describe the latest developments and results obtained in both gamma and alpha imaging techniques. The gamma camera has been used by the CEA since the 1990's and several changes have made this device more sensitive, more compact and more competitive for nuclear plant operations. It is used to quickly identify hot spots, locating irradiating sources from 50 keV to 1500 keV. Several examples from a wide field of applications will be presented, together with the very latest developments. The alpha camera is a new camera used to see invisible alpha contamination on several kinds of surfaces. The latest results obtained allow real time supervision of a glove box cleaning operation (for {sup 241}Am contamination). The detection principle as well as the main trials and results obtained will be presented. Secondly, this paper will focus on in situ gamma spectrometry methods developed by the CEA with compact gamma spectrometry probes (CdZnTe, LaBr{sub 3}, NaI, etc.). The radiological data collected is used to quantify the activity of hot spots and can also then be entered in 3D models of nuclear plants to simulate intervention scenarios. Recent developments and results will be presented regarding this. Finally, thanks to a large amount of feedback, the interest of using complementary measurements will be discussed. In fact, the recent use of 3D simulation codes requires very accurate knowledge of nuclear plant radiological data. The use of coupled devices such as imaging devices, (gamma and alpha cameras), gamma spectrometry, dose rate mapping, collimated / un-collimated measurements and many other physical values gives an approach to the radiological knowledge of a process or plant with the lowest possible uncertainty. In line with this, the paper will conclude with the future developments and trials that could be assessed in that field of application. (authors)« less

Heart Imaging System

NASA Technical Reports Server (NTRS)

1993-01-01

Johnson Space Flight Center's device to test astronauts' heart function in microgravity has led to the MultiWire Gamma Camera, which images heart conditions six times faster than conventional devices. Dr. Jeffrey Lacy, who developed the technology as a NASA researcher, later formed Proportional Technologies, Inc. to develop a commercially viable process that would enable use of Tantalum-178 (Ta-178), a radio-pharmaceutical. His company supplies the generator for the radioactive Ta-178 to Xenos Medical Systems, which markets the camera. Ta-178 can only be optimally imaged with the camera. Because the body is subjected to it for only nine minutes, the radiation dose is significantly reduced and the technique can be used more frequently. Ta-178 also enables the camera to be used on pediatric patients who are rarely studied with conventional isotopes because of the high radiation dosage.

Experimental Comparison of Knife-Edge and Multi-Parallel Slit Collimators for Prompt Gamma Imaging of Proton Pencil Beams.

PubMed

Smeets, Julien; Roellinghoff, Frauke; Janssens, Guillaume; Perali, Irene; Celani, Andrea; Fiorini, Carlo; Freud, Nicolas; Testa, Etienne; Prieels, Damien

2016-01-01

More and more camera concepts are being investigated to try and seize the opportunity of instantaneous range verification of proton therapy treatments offered by prompt gammas emitted along the proton tracks. Focusing on one-dimensional imaging with a passive collimator, the present study experimentally compared in combination with the first, clinically compatible, dedicated camera device the performances of instances of the two main options: a knife-edge slit (KES) and a multi-parallel slit (MPS) design. These two options were experimentally assessed in this specific context as they were previously demonstrated through analytical and numerical studies to allow similar performances in terms of Bragg peak retrieval precision and spatial resolution in a general context. Both collimators were prototyped according to the conclusions of Monte Carlo optimization studies under constraints of equal weight (40 mm tungsten alloy equivalent thickness) and of the specificities of the camera device under consideration (in particular 4 mm segmentation along beam axis and no time-of-flight discrimination, both of which less favorable to the MPS performance than to the KES one). Acquisitions of proton pencil beams of 100, 160, and 230 MeV in a PMMA target revealed that, in order to reach a given level of statistical precision on Bragg peak depth retrieval, the KES collimator requires only half the dose the present MPS collimator needs, making the KES collimator a preferred option for a compact camera device aimed at imaging only the Bragg peak position. On the other hand, the present MPS collimator proves more effective at retrieving the entrance of the beam in the target in the context of an extended camera device aimed at imaging the whole proton track within the patient.

Development of a single-photon-counting camera with use of a triple-stacked micro-channel plate.

PubMed

Yasuda, Naruomi; Suzuki, Hitoshi; Katafuchi, Tetsuro

2016-01-01

At the quantum-mechanical level, all substances (not merely electromagnetic waves such as light and X-rays) exhibit wave–particle duality. Whereas students of radiation science can easily understand the wave nature of electromagnetic waves, the particle (photon) nature may elude them. Therefore, to assist students in understanding the wave–particle duality of electromagnetic waves, we have developed a photon-counting camera that captures single photons in two-dimensional images. As an image intensifier, this camera has a triple-stacked micro-channel plate (MCP) with an amplification factor of 10(6). The ultra-low light of a single photon entering the camera is first converted to an electron through the photoelectric effect on the photocathode. The electron is intensified by the triple-stacked MCP and then converted to a visible light distribution, which is measured by a high-sensitivity complementary metal oxide semiconductor image sensor. Because it detects individual photons, the photon-counting camera is expected to provide students with a complete understanding of the particle nature of electromagnetic waves. Moreover, it measures ultra-weak light that cannot be detected by ordinary low-sensitivity cameras. Therefore, it is suitable for experimental research on scintillator luminescence, biophoton detection, and similar topics.

High-speed line-scan camera with digital time delay integration

NASA Astrophysics Data System (ADS)

Bodenstorfer, Ernst; Fürtler, Johannes; Brodersen, Jörg; Mayer, Konrad J.; Eckel, Christian; Gravogl, Klaus; Nachtnebel, Herbert

2007-02-01

Dealing with high-speed image acquisition and processing systems, the speed of operation is often limited by the amount of available light, due to short exposure times. Therefore, high-speed applications often use line-scan cameras, based on charge-coupled device (CCD) sensors with time delayed integration (TDI). Synchronous shift and accumulation of photoelectric charges on the CCD chip - according to the objects' movement - result in a longer effective exposure time without introducing additional motion blur. This paper presents a high-speed color line-scan camera based on a commercial complementary metal oxide semiconductor (CMOS) area image sensor with a Bayer filter matrix and a field programmable gate array (FPGA). The camera implements a digital equivalent to the TDI effect exploited with CCD cameras. The proposed design benefits from the high frame rates of CMOS sensors and from the possibility of arbitrarily addressing the rows of the sensor's pixel array. For the digital TDI just a small number of rows are read out from the area sensor which are then shifted and accumulated according to the movement of the inspected objects. This paper gives a detailed description of the digital TDI algorithm implemented on the FPGA. Relevant aspects for the practical application are discussed and key features of the camera are listed.

Note: Operation of gamma-ray microcalorimeters at elevated count rates using filters with constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alpert, B. K.; Horansky, R. D.; Bennett, D. A.

Microcalorimeter sensors operated near 0.1 K can measure the energy of individual x- and gamma-ray photons with significantly more precision than conventional semiconductor technologies. Both microcalorimeter arrays and higher per pixel count rates are desirable to increase the total throughput of spectrometers based on these devices. The millisecond recovery time of gamma-ray microcalorimeters and the resulting pulse pileup are significant obstacles to high per pixel count rates. Here, we demonstrate operation of a microcalorimeter detector at elevated count rates by use of convolution filters designed to be orthogonal to the exponential tail of a preceding pulse. These filters allow operationmore » at 50% higher count rates than conventional filters while largely preserving sensor energy resolution.« less

Electrical Characterization of Semiconductor Materials and Devices

NASA Astrophysics Data System (ADS)

Deen, M.; Pascal, Fabien

Semiconductor materials and devices continue to occupy a preeminent technological position due to their importance when building integrated electronic systems used in a wide range of applications from computers, cell-phones, personal digital assistants, digital cameras and electronic entertainment systems, to electronic instrumentation for medical diagnositics and environmental monitoring. Key ingredients of this technological dominance have been the rapid advances made in the quality and processing of materials - semiconductors, conductors and dielectrics - which have given metal oxide semiconductor device technology its important characteristics of negligible standby power dissipation, good input-output isolation, surface potential control and reliable operation. However, when assessing material quality and device reliability, it is important to have fast, nondestructive, accurate and easy-to-use electrical characterization techniques available, so that important parameters such as carrier doping density, type and mobility of carriers, interface quality, oxide trap density, semiconductor bulk defect density, contact and other parasitic resistances and oxide electrical integrity can be determined. This chapter describes some of the more widely employed and popular techniques that are used to determine these important parameters. The techniques presented in this chapter range in both complexity and test structure requirements from simple current-voltage measurements to more sophisticated low-frequency noise, charge pumping and deep-level transient spectroscopy techniques.

Field-deployable gamma-radiation detectors for DHS use

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Sanjoy

2007-09-01

Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS' requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER TM, which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack TM that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field1. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant spectral data and software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

Touch And Go Camera System (TAGCAMS) for the OSIRIS-REx Asteroid Sample Return Mission

NASA Astrophysics Data System (ADS)

Bos, B. J.; Ravine, M. A.; Caplinger, M.; Schaffner, J. A.; Ladewig, J. V.; Olds, R. D.; Norman, C. D.; Huish, D.; Hughes, M.; Anderson, S. K.; Lorenz, D. A.; May, A.; Jackman, C. D.; Nelson, D.; Moreau, M.; Kubitschek, D.; Getzandanner, K.; Gordon, K. E.; Eberhardt, A.; Lauretta, D. S.

2018-02-01

NASA's OSIRIS-REx asteroid sample return mission spacecraft includes the Touch And Go Camera System (TAGCAMS) three camera-head instrument. The purpose of TAGCAMS is to provide imagery during the mission to facilitate navigation to the target asteroid, confirm acquisition of the asteroid sample, and document asteroid sample stowage. The cameras were designed and constructed by Malin Space Science Systems (MSSS) based on requirements developed by Lockheed Martin and NASA. All three of the cameras are mounted to the spacecraft nadir deck and provide images in the visible part of the spectrum, 400-700 nm. Two of the TAGCAMS cameras, NavCam 1 and NavCam 2, serve as fully redundant navigation cameras to support optical navigation and natural feature tracking. Their boresights are aligned in the nadir direction with small angular offsets for operational convenience. The third TAGCAMS camera, StowCam, provides imagery to assist with and confirm proper stowage of the asteroid sample. Its boresight is pointed at the OSIRIS-REx sample return capsule located on the spacecraft deck. All three cameras have at their heart a 2592 × 1944 pixel complementary metal oxide semiconductor (CMOS) detector array that provides up to 12-bit pixel depth. All cameras also share the same lens design and a camera field of view of roughly 44° × 32° with a pixel scale of 0.28 mrad/pixel. The StowCam lens is focused to image features on the spacecraft deck, while both NavCam lens focus positions are optimized for imaging at infinity. A brief description of the TAGCAMS instrument and how it is used to support critical OSIRIS-REx operations is provided.

Wobbly strings: calculating the capture rate of a webcam using the rolling shutter effect in a guitar

NASA Astrophysics Data System (ADS)

Cunnah, David

2014-07-01

In this paper I propose a method of calculating the time between line captures in a standard complementary metal-oxide-semiconductor (CMOS) webcam using the rolling shutter effect when filming a guitar. The exercise links the concepts of wavelength and frequency, while outlining the basic operation of a CMOS camera through vertical line capture.

Wobbly Strings: Calculating the Capture Rate of a Webcam Using the Rolling Shutter Effect in a Guitar

ERIC Educational Resources Information Center

Cunnah, David

2014-01-01

In this paper I propose a method of calculating the time between line captures in a standard complementary metal-oxide-semiconductor (CMOS) webcam using the rolling shutter effect when filming a guitar. The exercise links the concepts of wavelength and frequency, while outlining the basic operation of a CMOS camera through vertical line capture.

In vitro near-infrared imaging of occlusal dental caries using a germanium-enhanced CMOS camera

NASA Astrophysics Data System (ADS)

Lee, Chulsung; Darling, Cynthia L.; Fried, Daniel

2010-02-01

The high transparency of dental enamel in the near-infrared (NIR) at 1310-nm can be exploited for imaging dental caries without the use of ionizing radiation. The objective of this study was to determine whether the lesion contrast derived from NIR transillumination can be used to estimate lesion severity. Another aim was to compare the performance of a new Ge enhanced complementary metal-oxide-semiconductor (CMOS) based NIR imaging camera with the InGaAs focal plane array (FPA). Extracted human teeth (n=52) with natural occlusal caries were imaged with both cameras at 1310-nm and the image contrast between sound and carious regions was calculated. After NIR imaging, teeth were sectioned and examined using more established methods, namely polarized light microscopy (PLM) and transverse microradiography (TMR) to calculate lesion severity. Lesions were then classified into 4 categories according to the lesion severity. Lesion contrast increased significantly with lesion severity for both cameras (p<0.05). The Ge enhanced CMOS camera equipped with the larger array and smaller pixels yielded higher contrast values compared with the smaller InGaAs FPA (p<0.01). Results demonstrate that NIR lesion contrast can be used to estimate lesion severity.

In vitro near-infrared imaging of occlusal dental caries using germanium enhanced CMOS camera.

PubMed

Lee, Chulsung; Darling, Cynthia L; Fried, Daniel

2010-03-01

The high transparency of dental enamel in the near-infrared (NIR) at 1310-nm can be exploited for imaging dental caries without the use of ionizing radiation. The objective of this study was to determine whether the lesion contrast derived from NIR transillumination can be used to estimate lesion severity. Another aim was to compare the performance of a new Ge enhanced complementary metal-oxide-semiconductor (CMOS) based NIR imaging camera with the InGaAs focal plane array (FPA). Extracted human teeth (n=52) with natural occlusal caries were imaged with both cameras at 1310-nm and the image contrast between sound and carious regions was calculated. After NIR imaging, teeth were sectioned and examined using more established methods, namely polarized light microscopy (PLM) and transverse microradiography (TMR) to calculate lesion severity. Lesions were then classified into 4 categories according to the lesion severity. Lesion contrast increased significantly with lesion severity for both cameras (p<0.05). The Ge enhanced CMOS camera equipped with the larger array and smaller pixels yielded higher contrast values compared with the smaller InGaAs FPA (p<0.01). Results demonstrate that NIR lesion contrast can be used to estimate lesion severity.

Photometric Calibration and Image Stitching for a Large Field of View Multi-Camera System

PubMed Central

Lu, Yu; Wang, Keyi; Fan, Gongshu

2016-01-01

A new compact large field of view (FOV) multi-camera system is introduced. The camera is based on seven tiny complementary metal-oxide-semiconductor sensor modules covering over 160° × 160° FOV. Although image stitching has been studied extensively, sensor and lens differences have not been considered in previous multi-camera devices. In this study, we have calibrated the photometric characteristics of the multi-camera device. Lenses were not mounted on the sensor in the process of radiometric response calibration to eliminate the influence of the focusing effect of uniform light from an integrating sphere. Linearity range of the radiometric response, non-linearity response characteristics, sensitivity, and dark current of the camera response function are presented. The R, G, and B channels have different responses for the same illuminance. Vignetting artifact patterns have been tested. The actual luminance of the object is retrieved by sensor calibration results, and is used to blend images to make panoramas reflect the objective luminance more objectively. This compensates for the limitation of stitching images that are more realistic only through the smoothing method. The dynamic range limitation of can be resolved by using multiple cameras that cover a large field of view instead of a single image sensor with a wide-angle lens. The dynamic range is expanded by 48-fold in this system. We can obtain seven images in one shot with this multi-camera system, at 13 frames per second. PMID:27077857

MOXE: An X-ray all-sky monitor for Soviet Spectrum-X-Gamma Mission

NASA Technical Reports Server (NTRS)

Priedhorsky, W.; Fenimore, E. E.; Moss, C. E.; Kelley, R. L.; Holt, S. S.

1989-01-01

A Monitoring Monitoring X-Ray Equipment (MOXE) is being developed for the Soviet Spectrum-X-Gamma Mission. MOXE is an X-ray all-sky monitor based on array of pinhole cameras, to be provided via a collaboration between Goddard Space Flight Center and Los Alamos National Laboratory. The objectives are to alert other observers on Spectrum-X-Gamma and other platforms of interesting transient activity, and to synoptically monitor the X-ray sky and study long-term changes in X-ray binaries. MOXE will be sensitive to sources as faint as 2 milliCrab (5 sigma) in 1 day, and cover the 2 to 20 KeV band.

Elemental abundances of the B and A stars Gamma Geminorum, 7 Sextantis, HR 4817, and HR 5780

NASA Technical Reports Server (NTRS)

Adelman, Saul J.; Philip, A. G. D.

1992-01-01

Fine analyses of the B and A stars, Gamma Geminorum, 7 Sextantis, HR 4817, and HR 5780 are performed. Although the data cover rather limited spectral regions, still useful results were obtained. The data were mostly obtained at the KPNO coude feed telescope with CCD TI No. 3, camera 5, and grating A. The He/H ratio of HR 4817 confirms the similarity of many abundance values with those of the peculiar Mn star 53 Tauri. For the most part Gamma Gem, 7 Sex, and HR 5780 have derived abundances similar to those of other normal sharp-lined stars of similar effective temperature.

Aging of electronics with application to nuclear power plant instrumentation. [PWR; BWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Jr, R T; Thome, F V; Craft, C M

1983-01-01

A survey to identify areas of needed research to understand aging mechanisms for electronics in nuclear power plant instrumentation has been completed. The emphasis was on electronic components such as semiconductors, capacitors, and resistors used in safety-related instrumentation in the reactor containment area. The environmental and operational stress factors which may produce degradation during long-term operation were identified. Some attention was also given to humidity effects as related to seals and encapsulants, and failures in printed circuit boards and bonds and solder joints. Results suggest that neutron as well as gamma irradiations should be considered in simulating the aging environmentmore » for electronic components. Radiation dose-rate effects in semiconductor devices and organic capacitors need to be further investigated, as well as radiation-voltage bias synergistic effects in semiconductor devices and leakage and permeation of moisture through seals in electronics packages.« less

A machine learning method for fast and accurate characterization of depth-of-interaction gamma cameras

NASA Astrophysics Data System (ADS)

Pedemonte, Stefano; Pierce, Larry; Van Leemput, Koen

2017-11-01

Measuring the depth-of-interaction (DOI) of gamma photons enables increasing the resolution of emission imaging systems. Several design variants of DOI-sensitive detectors have been recently introduced to improve the performance of scanners for positron emission tomography (PET). However, the accurate characterization of the response of DOI detectors, necessary to accurately measure the DOI, remains an unsolved problem. Numerical simulations are, at the state of the art, imprecise, while measuring directly the characteristics of DOI detectors experimentally is hindered by the impossibility to impose the depth-of-interaction in an experimental set-up. In this article we introduce a machine learning approach for extracting accurate forward models of gamma imaging devices from simple pencil-beam measurements, using a nonlinear dimensionality reduction technique in combination with a finite mixture model. The method is purely data-driven, not requiring simulations, and is applicable to a wide range of detector types. The proposed method was evaluated both in a simulation study and with data acquired using a monolithic gamma camera designed for PET (the cMiCE detector), demonstrating the accurate recovery of the DOI characteristics. The combination of the proposed calibration technique with maximum- a posteriori estimation of the coordinates of interaction provided a depth resolution of  ≈1.14 mm for the simulated PET detector and  ≈1.74 mm for the cMiCE detector. The software and experimental data are made available at http://occiput.mgh.harvard.edu/depthembedding/.

The research of adaptive-exposure on spot-detecting camera in ATP system

NASA Astrophysics Data System (ADS)

Qian, Feng; Jia, Jian-jun; Zhang, Liang; Wang, Jian-Yu

2013-08-01

High precision acquisition, tracking, pointing (ATP) system is one of the key techniques of laser communication. The spot-detecting camera is used to detect the direction of beacon in laser communication link, so that it can get the position information of communication terminal for ATP system. The positioning accuracy of camera decides the capability of laser communication system directly. So the spot-detecting camera in satellite-to-earth laser communication ATP systems needs high precision on target detection. The positioning accuracy of cameras should be better than +/-1μ rad . The spot-detecting cameras usually adopt centroid algorithm to get the position information of light spot on detectors. When the intensity of beacon is moderate, calculation results of centroid algorithm will be precise. But the intensity of beacon changes greatly during communication for distance, atmospheric scintillation, weather etc. The output signal of detector will be insufficient when the camera underexposes to beacon because of low light intensity. On the other hand, the output signal of detector will be saturated when the camera overexposes to beacon because of high light intensity. The calculation accuracy of centroid algorithm becomes worse if the spot-detecting camera underexposes or overexposes, and then the positioning accuracy of camera will be reduced obviously. In order to improve the accuracy, space-based cameras should regulate exposure time in real time according to light intensity. The algorithm of adaptive-exposure technique for spot-detecting camera based on metal-oxide-semiconductor (CMOS) detector is analyzed. According to analytic results, a CMOS camera in space-based laser communication system is described, which utilizes the algorithm of adaptive-exposure to adapting exposure time. Test results from imaging experiment system formed verify the design. Experimental results prove that this design can restrain the reduction of positioning accuracy for the change of light intensity. So the camera can keep stable and high positioning accuracy during communication.

Single-view 3D reconstruction of correlated gamma-neutron sources

DOE PAGES

Monterial, Mateusz; Marleau, Peter; Pozzi, Sara A.

2017-01-05

We describe a new method of 3D image reconstruction of neutron sources that emit correlated gammas (e.g. Cf- 252, Am-Be). This category includes a vast majority of neutron sources important in nuclear threat search, safeguards and non-proliferation. Rather than requiring multiple views of the source this technique relies on the source’s intrinsic property of coincidence gamma and neutron emission. As a result only a single-view measurement of the source is required to perform the 3D reconstruction. In principle, any scatter camera sensitive to gammas and neutrons with adequate timing and interaction location resolution can perform this reconstruction. Using a neutronmore » double scatter technique, we can calculate a conical surface of possible source locations. By including the time to a correlated gamma we further constrain the source location in three-dimensions by solving for the source-to-detector distance along the surface of said cone. As a proof of concept we applied these reconstruction techniques on measurements taken with the the Mobile Imager of Neutrons for Emergency Responders (MINER). Two Cf-252 sources measured at 50 and 60 cm from the center of the detector were resolved in their varying depth with average radial distance relative resolution of 26%. To demonstrate the technique’s potential with an optimized system we simulated the measurement in MCNPX-PoliMi assuming timing resolution of 200 ps (from 2 ns in the current system) and source interaction location resolution of 5 mm (from 3 cm). Furthermore, these simulated improvements in scatter camera performance resulted in radial distance relative resolution decreasing to an average of 11%.« less

Single-view 3D reconstruction of correlated gamma-neutron sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monterial, Mateusz; Marleau, Peter; Pozzi, Sara A.

We describe a new method of 3D image reconstruction of neutron sources that emit correlated gammas (e.g. Cf- 252, Am-Be). This category includes a vast majority of neutron sources important in nuclear threat search, safeguards and non-proliferation. Rather than requiring multiple views of the source this technique relies on the source’s intrinsic property of coincidence gamma and neutron emission. As a result only a single-view measurement of the source is required to perform the 3D reconstruction. In principle, any scatter camera sensitive to gammas and neutrons with adequate timing and interaction location resolution can perform this reconstruction. Using a neutronmore » double scatter technique, we can calculate a conical surface of possible source locations. By including the time to a correlated gamma we further constrain the source location in three-dimensions by solving for the source-to-detector distance along the surface of said cone. As a proof of concept we applied these reconstruction techniques on measurements taken with the the Mobile Imager of Neutrons for Emergency Responders (MINER). Two Cf-252 sources measured at 50 and 60 cm from the center of the detector were resolved in their varying depth with average radial distance relative resolution of 26%. To demonstrate the technique’s potential with an optimized system we simulated the measurement in MCNPX-PoliMi assuming timing resolution of 200 ps (from 2 ns in the current system) and source interaction location resolution of 5 mm (from 3 cm). Furthermore, these simulated improvements in scatter camera performance resulted in radial distance relative resolution decreasing to an average of 11%.« less

Bright and ultra-fast scintillation from a semiconductor?

PubMed Central

Derenzo, Stephen E.; Bourret-Courshesne, Edith; Bizarri, Gregory; Canning, Andrew

2015-01-01

Semiconductor scintillators are worth studying because they include both the highest luminosities and shortest decay times of all known scintillators. Moreover, many semiconductors have the heaviest stable elements (Tl, Hg, Pb, Bi) as a major constituent and a high ion pair yield that is proportional to the energy deposited. We review the scintillation properties of semiconductors activated by native defects, isoelectronic impurities, donors and acceptors with special emphasis on those that have exceptionally high luminosities (e.g. ZnO:Zn, ZnS:Ag,Cl, CdS:Ag,Cl) and those that have ultra-fast decay times (e.g. ZnO:Ga; CdS:In). We discuss underlying mechanisms that are consistent with these properties and the possibilities for achieving (1) 200,000 photons/MeV and 1% fwhm energy resolution for 662 keV gamma rays, (2) ultra-fast (ns) decay times and coincident resolving times of 30 ps fwhm for time-of-flight positron emission tomography, and (3) both a high luminosity and an ultra-fast decay time from the same scintillator at cryogenic temperatures. PMID:26855462

Time-dependent spatial intensity profiles of near-infrared idler pulses from nanosecond optical parametric oscillators

NASA Astrophysics Data System (ADS)

Olafsen, L. J.; Olafsen, J. S.; Eaves, I. K.

2018-06-01

We report on an experimental investigation of the time-dependent spatial intensity distribution of near-infrared idler pulses from an optical parametric oscillator measured using an infrared (IR) camera, in contrast to beam profiles obtained using traditional knife-edge techniques. Comparisons show the information gained by utilizing the thermal camera provides more detail than the spatially- or time-averaged measurements from a knife-edge profile. Synchronization, averaging, and thresholding techniques are applied to enhance the images acquired. The additional information obtained can improve the process by which semiconductor devices and other IR lasers are characterized for their beam quality and output response and thereby result in IR devices with higher performance.

Practical aspects of modern interferometry for optical manufacturing quality control: Part 2

NASA Astrophysics Data System (ADS)

Smythe, Robert

2012-07-01

Modern phase shifting interferometers enable the manufacture of optical systems that drive the global economy. Semiconductor chips, solid-state cameras, cell phone cameras, infrared imaging systems, space based satellite imaging and DVD and Blu-Ray disks are all enabled by phase shifting interferometers. Theoretical treatments of data analysis and instrument design advance the technology but often are not helpful towards the practical use of interferometers. An understanding of the parameters that drive system performance is critical to produce useful results. Any interferometer will produce a data map and results; this paper, in three parts, reviews some of the key issues to minimize error sources in that data and provide a valid measurement.

Practical aspects of modern interferometry for optical manufacturing quality control, Part 3

NASA Astrophysics Data System (ADS)

Smythe, Robert A.

2012-09-01

Modern phase shifting interferometers enable the manufacture of optical systems that drive the global economy. Semiconductor chips, solid-state cameras, cell phone cameras, infrared imaging systems, space-based satellite imaging, and DVD and Blu-Ray disks are all enabled by phase-shifting interferometers. Theoretical treatments of data analysis and instrument design advance the technology but often are not helpful toward the practical use of interferometers. An understanding of the parameters that drive the system performance is critical to produce useful results. Any interferometer will produce a data map and results; this paper, in three parts, reviews some of the key issues to minimize error sources in that data and provide a valid measurement.

Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild-Couder telescope prototype for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Dournaux, J. L.; De Franco, A.; Laporte, P.; White, R.; Greenshaw, T.; Sol, H.; Abchiche, A.; Allan, D.; Amans, J. P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J. J.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M.; De Frondat, F.; Dumas, D.; Ernenwein, J. P.; Fasola, G.; Funk, S.; Gaudemard, J.; Graham, J. A.; Gironnet, J.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J. M.; Jégouzo, I.; Jogler, T.; Kawashima, T.; Kraus, M.; Lapington, J. S.; Lefaucheur, J.; Markoff, S.; Melse, T.; Morhrmann, L.; Molnyeux, P.; Nolan, S. J.; Okumura, A.; Parsons, R. D.; Ross, D.; Rowell, G.; Sato, Y.; Sayède, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Vink, J.; Watson, J.; Yamane, N.; Zech, A.; Zink, A.; CTA Consortium

2017-02-01

The Cherenkov Telescope Array (CTA) consortium aims to build the next-generation ground-based very-high-energy gamma-ray observatory. The array will feature different sizes of telescopes allowing it to cover a wide gamma-ray energy band from about 20 GeV to above 100 TeV. The highest energies, above 5 TeV, will be covered by a large number of Small-Sized Telescopes (SSTs) with a field-of-view of around 9°. The Gamma-ray Cherenkov Telescope (GCT), based on Schwarzschild-Couder dual-mirror optics, is one of the three proposed SST designs. The GCT is described in this contribution and the first images of Cherenkov showers obtained using the telescope and its camera are presented. These were obtained in November 2015 in Meudon,

Thyroid Scan and Uptake

MedlinePlus

... minutes prior to the test. When it is time for the imaging to begin, you will lie down on a moveable examination table with your head tipped backward and neck extended. The gamma camera will then take a series of images, capturing images of the thyroid gland ...

Gamma-camera 18F-FDG PET in diagnosis and staging of patients presenting with suspected lung cancer and comparison with dedicated PET.

PubMed

Oturai, Peter S; Mortensen, Jann; Enevoldsen, Henriette; Eigtved, Annika; Backer, Vibeke; Olesen, Knud P; Nielsen, Henrik W; Hansen, Hanne; Stentoft, Poul; Friberg, Lars

2004-08-01

It is not clear whether high-quality coincidence gamma-PET (gPET) cameras can provide clinical data comparable with data obtained with dedicated PET (dPET) cameras in the primary diagnostic work-up of patients with suspected lung cancer. This study focuses on 2 main issues: direct comparison between foci resolved with the 2 different PET scanners and the diagnostic accuracy compared with final diagnosis determined by the combined information from all other investigations and clinical follow-up. Eighty-six patients were recruited to this study through a routine diagnostic program. They all had changes on their chest radiographs, suggesting malignant lung tumor. In addition to the standard diagnostic program, each patient had 2 PET scans that were performed on the same day. After administration of 419 MBq (range = 305-547 MBq) (18)F-FDG, patients were scanned in a dedicated PET scanner about 1 h after FDG administration and in a dual-head coincidence gamma-camera about 3 h after tracer injection. Images from the 2 scans were evaluated in a blinded set-up and compared with the final outcome. Malignant intrathoracic disease was found in 52 patients, and 47 patients had primary lung cancers. dPET detected all patients as having malignancies (sensitivity, 100%; specificity, 50%), whereas gPET missed one patient (sensitivity, 98%; specificity, 56%). For evaluating regional lymph node involvement, sensitivity and specificity rates were 78% and 84% for dPET and 61% and 90% for gPET, respectively. When comparing the 2 PET techniques with clinical tumor stage (TNM), full agreement was obtained in 64% of the patients (Cohen's kappa = 0.56). Comparing categorization of the patients into clinical relevant stages (no malignancy/malignancy suitable for treatment with curative intent/nontreatable malignancy), resulted in full agreement in 81% (Cohen's kappa = 0.71) of patients. Comparing results from a recent generation of gPET cameras obtained about 2 h later than those of dPET, there was a fairly good agreement with regard to detecting primary lung tumors but slightly reduced sensitivity in detecting smaller malignant lesions such as lymph nodes. Depending on the population to be investigated, and if dPET is not available, gPET might provide significant diagnostic information in patients in whom lung cancer is suspected.

Neutron Imaging Camera

NASA Technical Reports Server (NTRS)

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

2008-01-01

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

Development of a Compton camera for medical applications based on silicon strip and scintillation detectors

NASA Astrophysics Data System (ADS)

Krimmer, J.; Ley, J.-L.; Abellan, C.; Cachemiche, J.-P.; Caponetto, L.; Chen, X.; Dahoumane, M.; Dauvergne, D.; Freud, N.; Joly, B.; Lambert, D.; Lestand, L.; Létang, J. M.; Magne, M.; Mathez, H.; Maxim, V.; Montarou, G.; Morel, C.; Pinto, M.; Ray, C.; Reithinger, V.; Testa, E.; Zoccarato, Y.

2015-07-01

A Compton camera is being developed for the purpose of ion-range monitoring during hadrontherapy via the detection of prompt-gamma rays. The system consists of a scintillating fiber beam tagging hodoscope, a stack of double sided silicon strip detectors (90×90×2 mm3, 2×64 strips) as scatter detectors, as well as bismuth germanate (BGO) scintillation detectors (38×35×30 mm3, 100 blocks) as absorbers. The individual components will be described, together with the status of their characterization.

A panoramic coded aperture gamma camera for radioactive hotspots localization

NASA Astrophysics Data System (ADS)

Paradiso, V.; Amgarou, K.; Blanc De Lanaute, N.; Schoepff, V.; Amoyal, G.; Mahe, C.; Beltramello, O.; Liénard, E.

2017-11-01

A known disadvantage of the coded aperture imaging approach is its limited field-of-view (FOV), which often results insufficient when analysing complex dismantling scenes such as post-accidental scenarios, where multiple measurements are needed to fully characterize the scene. In order to overcome this limitation, a panoramic coded aperture γ-camera prototype has been developed. The system is based on a 1 mm thick CdTe detector directly bump-bonded to a Timepix readout chip, developed by the Medipix2 collaboration (256 × 256 pixels, 55 μm pitch, 14.08 × 14.08 mm2 sensitive area). A MURA pattern coded aperture is used, allowing for background subtraction without the use of heavy shielding. Such system is then combined with a USB color camera. The output of each measurement is a semi-spherical image covering a FOV of 360 degrees horizontally and 80 degrees vertically, rendered in spherical coordinates (θ,phi). The geometrical shapes of the radiation-emitting objects are preserved by first registering and stitching the optical images captured by the prototype, and applying, subsequently, the same transformations to their corresponding radiation images. Panoramic gamma images generated by using the technique proposed in this paper are described and discussed, along with the main experimental results obtained in laboratories campaigns.

A neutron camera system for MAST.

PubMed

Cecconello, M; Turnyanskiy, M; Conroy, S; Ericsson, G; Ronchi, E; Sangaroon, S; Akers, R; Fitzgerald, I; Cullen, A; Weiszflog, M

2010-10-01

A prototype neutron camera has been developed and installed at MAST as part of a feasibility study for a multichord neutron camera system with the aim to measure the spatial and time resolved 2.45 MeV neutron emissivity profile. Liquid scintillators coupled to a fast digitizer are used for neutron/gamma ray digital pulse shape discrimination. The preliminary results obtained clearly show the capability of this diagnostic to measure neutron emissivity profiles with sufficient time resolution to study the effect of fast ion loss and redistribution due to magnetohydrodynamic activity. A minimum time resolution of 2 ms has been achieved with a modest 1.5 MW of neutral beam injection heating with a measured neutron count rate of a few 100 kHz.

Hybrid radioguided occult lesion localization (hybrid ROLL) of (18)F-FDG-avid lesions using the hybrid tracer indocyanine green-(99m)Tc-nanocolloid.

PubMed

KleinJan, G H; Brouwer, O R; Mathéron, H M; Rietbergen, D D D; Valdés Olmos, R A; Wouters, M W; van den Berg, N S; van Leeuwen, F W B

2016-01-01

To assess if combined fluorescence- and radio-guided occult lesion localization (hybrid ROLL) is feasible in patients scheduled for surgical resection of non-palpable (18)F-FDG-avid lesions on PET/CT. Four patients with (18)F-FDG-avid lesions on follow-up PET/CT that were not palpable during physical examination but were suspected to harbor metastasis were enrolled. Guided by ultrasound, the hybrid tracer indocyanine green (ICG)-(99m)Tc-nanocolloid was injected centrally in the target lesion. SPECT/CT imaging was used to confirm tracer deposition. Intraoperatively, lesions were localized using a hand-held gamma ray detection probe, a portable gamma camera, and a fluorescence camera. After excision, the gamma camera was used to check the wound bed for residual activity. A total of six (18)F-FDG-avid lymph nodes were identified and scheduled for hybrid ROLL. Comparison of the PET/CT images with the acquired SPECT/CT after hybrid tracer injection confirmed accurate tracer deposition. No side effects were observed. Combined radio- and fluorescence-guidance enabled localization and excision of the target lesion in all patients. Five of the six excised lesions proved tumor-positive at histopathology. The hybrid ROLL approach appears to be feasible and can facilitate the intraoperative localization and excision of non-palpable lesions suspected to harbor tumor metastases. In addition to the initial radioguided detection, the fluorescence component of the hybrid tracer enables high-resolution intraoperative visualization of the target lesion. The procedure needs further evaluation in a larger cohort and wider range of malignancies to substantiate these preliminary findings. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Design of optimal collimation for dedicated molecular breast imaging systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinmann, Amanda L.; Hruska, Carrie B.; O'Connor, Michael K.

2009-03-15

Molecular breast imaging (MBI) is a functional imaging technique that uses specialized small field-of-view gamma cameras to detect the preferential uptake of a radiotracer in breast lesions. MBI has potential to be a useful adjunct method to screening mammography for the detection of occult breast cancer. However, a current limitation of MBI is the high radiation dose (a factor of 7-10 times that of screening mammography) associated with current technology. The purpose of this study was to optimize the gamma camera collimation with the aim of improving sensitivity while retaining adequate resolution for the detection of sub-10-mm lesions. Square-hole collimatorsmore » with holes matched to the pixilated cadmium zinc telluride detector elements of the MBI system were designed. Data from MBI patient studies and parameters of existing dual-head MBI systems were used to guide the range of desired collimator resolutions, source-to-collimator distances, pixel sizes, and collimator materials that were examined. General equations describing collimator performance for a conventional gamma camera were used in the design process along with several important adjustments to account for the specialized imaging geometry of the MBI system. Both theoretical calculations and a Monte Carlo model were used to measure the geometric efficiency (or sensitivity) and resolution of each designed collimator. Results showed that through optimal collimation, collimator sensitivity could be improved by factors of 1.5-3.2, while maintaining a collimator resolution of either {<=}5 or {<=}7.5 mm at a distance of 3 cm from the collimator face. These gains in collimator sensitivity permit an inversely proportional drop in the required dose to perform MBI.« less

Development of an intraoperative gamma camera based on a 256-pixel mercuric iodide detector array

NASA Astrophysics Data System (ADS)

Patt, B. E.; Tornai, M. P.; Iwanczyk, J. S.; Levin, C. S.; Hoffman, E. J.

1997-06-01

A 256-element mercuric iodide (HgI/sub 2/) detector array has been developed which is intended for use as an intraoperative gamma camera (IOGC). The camera is specifically designed for use in imaging gamma-emitting radiopharmaceuticals (such as 99m-Tc labeled Sestamibi) incorporated into brain tumors in the intraoperative surgical environment. The system is intended to improve the success of tumor removal surgeries by allowing more complete removal of subclinical tumor cells without removal of excessive normal tissue. The use of HgI/sub 2/ detector arrays in this application facilitates construction of an imaging head that is very compact and has a high SNR. The detector is configured as a cross-grid array. Pixel dimensions are 1.25 mm squares separated by 0.25 mm. The overall dimension of the detector is 23.75 mm on a side. The detector thickness is 1 mm which corresponds to over 60% stopping at 140 keV. The array has good uniformity with average energy resolution of 5.2/spl plusmn/2.9% FWHM at 140 keV (best resolution was 1.9% FWHM). Response uniformity (/spl plusmn//spl sigma/) was 7.9%. A study utilizing realistic tumor phantoms (uptake ratio varied from 2:1 to 100:1) in background (1 mCi/l) was conducted. SNRs for the reasonably achievable uptake ratio of 50:1 were 5.61 /spl sigma/ with 1 cm of background depth ("normal tissue") and 2.74 /spl sigma/ with 4 cm of background for a 6.3 /spl mu/l tumor phantom (/spl sim/270 nCi at the time of the measurement).

Continuous on-line monitoring of left ventricular function with a new nonimaging detector:validation and clinical use in the evaluation of patients post angioplasty.

PubMed

Breisblatt, W M; Schulman, D S; Follansbee, W P

1991-06-01

A new miniaturized nonimaging radionuclide detector (Cardioscint, Oxford, England) was evaluated for the continuous on-line assessment of left ventricular function. This cesium iodide probe can be placed on the patient's chest and can be interfaced to an IBM compatible personal computer conveniently placed at the patient's bedside. This system can provide a beat-to-beat or gated determination of left ventricular ejection fraction and ST segment analysis. In 28 patients this miniaturized probe was correlated against a high resolution gamma camera study. Over a wide range of ejection fraction (31% to 76%) in patients with and without regional wall motion abnormalities, the correlation between the Cardioscint detector and the gamma camera was excellent (r = 0.94, SEE +/- 2.1). This detector system has high temporal (10 msec) resolution, and comparison of peak filling rate (PFR) and time to peak filling (TPFR) also showed close agreement with the gamma camera (PFR, r = 0.94, SEE +/- 0.17; TPFR, r = 0.92, SEE +/- 6.8). In 18 patients on bed rest the long-term stability of this system for measuring ejection fraction and ST segments was verified. During the monitoring period (108 +/- 28 minutes) only minor changes in ejection fraction occurred (coefficient of variation 0.035 +/- 0.016) and ST segment analysis showed no significant change from baseline. To determine whether continuous on-line measurement of ejection fraction would be useful after coronary angioplasty, 12 patients who had undergone a successful procedure were evaluated for 280 +/- 35 minutes with the Cardioscint system.(ABSTRACT TRUNCATED AT 250 WORDS)

Compact Autonomous Hemispheric Vision System

NASA Technical Reports Server (NTRS)

Pingree, Paula J.; Cunningham, Thomas J.; Werne, Thomas A.; Eastwood, Michael L.; Walch, Marc J.; Staehle, Robert L.

2012-01-01

Solar System Exploration camera implementations to date have involved either single cameras with wide field-of-view (FOV) and consequently coarser spatial resolution, cameras on a movable mast, or single cameras necessitating rotation of the host vehicle to afford visibility outside a relatively narrow FOV. These cameras require detailed commanding from the ground or separate onboard computers to operate properly, and are incapable of making decisions based on image content that control pointing and downlink strategy. For color, a filter wheel having selectable positions was often added, which added moving parts, size, mass, power, and reduced reliability. A system was developed based on a general-purpose miniature visible-light camera using advanced CMOS (complementary metal oxide semiconductor) imager technology. The baseline camera has a 92 FOV and six cameras are arranged in an angled-up carousel fashion, with FOV overlaps such that the system has a 360 FOV (azimuth). A seventh camera, also with a FOV of 92 , is installed normal to the plane of the other 6 cameras giving the system a > 90 FOV in elevation and completing the hemispheric vision system. A central unit houses the common electronics box (CEB) controlling the system (power conversion, data processing, memory, and control software). Stereo is achieved by adding a second system on a baseline, and color is achieved by stacking two more systems (for a total of three, each system equipped with its own filter.) Two connectors on the bottom of the CEB provide a connection to a carrier (rover, spacecraft, balloon, etc.) for telemetry, commands, and power. This system has no moving parts. The system's onboard software (SW) supports autonomous operations such as pattern recognition and tracking.

An HDR imaging method with DTDI technology for push-broom cameras

NASA Astrophysics Data System (ADS)

Sun, Wu; Han, Chengshan; Xue, Xucheng; Lv, Hengyi; Shi, Junxia; Hu, Changhong; Li, Xiangzhi; Fu, Yao; Jiang, Xiaonan; Huang, Liang; Han, Hongyin

2018-03-01

Conventionally, high dynamic-range (HDR) imaging is based on taking two or more pictures of the same scene with different exposure. However, due to a high-speed relative motion between the camera and the scene, it is hard for this technique to be applied to push-broom remote sensing cameras. For the sake of HDR imaging in push-broom remote sensing applications, the present paper proposes an innovative method which can generate HDR images without redundant image sensors or optical components. Specifically, this paper adopts an area array CMOS (complementary metal oxide semiconductor) with the digital domain time-delay-integration (DTDI) technology for imaging, instead of adopting more than one row of image sensors, thereby taking more than one picture with different exposure. And then a new HDR image by fusing two original images with a simple algorithm can be achieved. By conducting the experiment, the dynamic range (DR) of the image increases by 26.02 dB. The proposed method is proved to be effective and has potential in other imaging applications where there is a relative motion between the cameras and scenes.

Positron Annihilation Induced Auger and Gamma Spectroscopy of Catalytically Important Surfaces

NASA Astrophysics Data System (ADS)

Weiss, A. H.; Nadesalingam, M. P.; Sundaramoorthy, R.; Mukherjee, S.; Fazleev, N. G.

2006-10-01

The annihilation of positrons with core electrons results in unique signatures in the spectra of Auger-electron and annihilation-gamma rays that can be used to make clear chemical identification of atoms at the surface. Because positrons implanted at low energies are trapped with high efficiency in the image-correlation well where they are localized just outside the surface it is possible to use annihilation induced Auger and Gamma signals to probe the surfaces of solids with single atomic layer depth resolution. In this talk we will report recent applications of Positron Annihilation Induced Auger Electron Spectroscopy (PAES) and Auger-Gamma Coincidence Spectroscopy (AGCS) to the study of surface structure and surface chemistry. Our research has demonstrated that PAES spectra can provide new information regarding the composition of the top-most atomic layer. Applications of PAES to the study of catalytically important surfaces of oxides and wide band-gap semiconductors including TiO2, SiO2,Cu2O, and SiC will be presented. We conclude with a discussion of the use of Auger-Gamma and Gamma-Gamma coincidence spectroscopy for the study of surfaces at pressures closer to those found in practical chemical reactors. Research supported by the Welch Foundation Grant Number Y-1100.

The next evolution in radioguided surgery: breast cancer related sentinel node localization using a freehandSPECT-mobile gamma camera combination

PubMed Central

Engelen, Thijs; Winkel, Beatrice MF; Rietbergen, Daphne DD; KleinJan, Gijs H; Vidal-Sicart, Sergi; Olmos, Renato A Valdés; van den Berg, Nynke S; van Leeuwen, Fijs WB

2015-01-01

Accurate pre- and intraoperative identification of the sentinel node (SN) forms the basis of the SN biopsy procedure. Gamma tracing technologies such as a gamma probe (GP), a 2D mobile gamma camera (MGC) or 3D freehandSPECT (FHS) can be used to provide the surgeon with radioguidance to the SN(s). We reasoned that integrated use of these technologies results in the generation of a “hybrid” modality that combines the best that the individual radioguidance technologies have to offer. The sensitivity and resolvability of both 2D-MGC and 3D-FHS-MGC were studied in a phantom setup (at various source-detector depths and using varying injection site-to-SN distances), and in ten breast cancer patients scheduled for SN biopsy. Acquired 3D-FHS-MGC images were overlaid with the position of the phantom/patient. This augmented-reality overview image was then used for navigation to the hotspot/SN in virtual-reality using the GP. Obtained results were compared to conventional gamma camera lymphoscintigrams. Resolution of 3D-FHS-MGC allowed identification of the SNs at a minimum injection site (100 MBq)-to-node (1 MBq; 1%) distance of 20 mm, up to a source-detector depth of 36 mm in 2D-MGC and up to 24 mm in 3D-FHS-MGC. A clinically relevant dose of approximately 1 MBq was clearly detectable up to a depth of 60 mm in 2D-MGC and 48 mm in 3D-FHS-MGC. In all ten patients at least one SN was visualized on the lymphoscintigrams with a total of 12 SNs visualized. 3D-FHS-MGC identified 11 of 12 SNs and allowed navigation to all these visualized SNs; in one patient with two axillary SNs located closely to each other (11 mm), 3D-FHS-MGC was not able to distinguish the two SNs. In conclusion, high sensitivity detection of SNs at an injection site-to-node distance of 20 mm-and-up was possible using 3D-FHS-MGC. In patients, 3D-FHS-MGC showed highly reproducible images as compared to the conventional lymphoscintigrams. PMID:26069857

Scalable gamma-ray camera for wide-area search based on silicon photomultipliers array

NASA Astrophysics Data System (ADS)

Jeong, Manhee; Van, Benjamin; Wells, Byron T.; D'Aries, Lawrence J.; Hammig, Mark D.

2018-03-01

Portable coded-aperture imaging systems based on scintillators and semiconductors have found use in a variety of radiological applications. For stand-off detection of weakly emitting materials, large volume detectors can facilitate the rapid localization of emitting materials. We describe a scalable coded-aperture imaging system based on 5.02 × 5.02 cm2 CsI(Tl) scintillator modules, each partitioned into 4 × 4 × 20 mm3 pixels that are optically coupled to 12 × 12 pixel silicon photo-multiplier (SiPM) arrays. The 144 pixels per module are read-out with a resistor-based charge-division circuit that reduces the readout outputs from 144 to four signals per module, from which the interaction position and total deposited energy can be extracted. All 144 CsI(Tl) pixels are readily distinguishable with an average energy resolution, at 662 keV, of 13.7% FWHM, a peak-to-valley ratio of 8.2, and a peak-to-Compton ratio of 2.9. The detector module is composed of a SiPM array coupled with a 2 cm thick scintillator and modified uniformly redundant array mask. For the image reconstruction, cross correlation and maximum likelihood expectation maximization methods are used. The system shows a field of view of 45° and an angular resolution of 4.7° FWHM.

Potential clinical impact of radionuclide imaging technologies: highlights of the ITBS 2003 meeting

NASA Astrophysics Data System (ADS)

Itti, Roland

2004-07-01

Radiopharmaceuticals are major determinants of progress in Nuclear Medicine. Besides 18FDG, the most common PET tracer, several other molecules are under evaluation, such as 18F-fluoride for bone studies, numerous ligands for neurotransmission, 18F-DOPA for neuro-endocrine tumors or generator produced 68Ga-peptides for various cancers. Nuclear medicine gradually changes for "molecular imaging" and medical imaging, which was at the beginning mainly anatomic, has progressed in the direction of functional and metabolic imaging. The present challenge is to achieve some degree of "in vivo" biochemistry or even histology or genetics. The importance of anatomic/functional image fusion justifies the development of combined PET-CT instrumentation, whose objectives have to be discussed in terms of anatomical landmarks and/or additional clinical information. The question of "hard" or "soft" image co-registration remains open, involving not only CT, but also SPECT or MRI. Development of dedicated imaging devices, whether single photon or positron, is of major interest for breast imaging, allowing optimal imaging conditions, with results definitely superior to classical gamma-cameras or PET. The patient population concerned with scintimammography is still controversial, as well as the imaging modalities: FDG or sestaMIBI, planar or tomographic, scintillators or semi-conductors, and the research field remains open. This is also valid for external or per-operative probe systems for tumor or lymph nodes localization.

Localization and spectral isolation of special nuclear material using stochastic image reconstruction

NASA Astrophysics Data System (ADS)

Hamel, M. C.; Polack, J. K.; Poitrasson-Rivière, A.; Clarke, S. D.; Pozzi, S. A.

2017-01-01

In this work we present a technique for isolating the gamma-ray and neutron energy spectra from multiple radioactive sources localized in an image. Image reconstruction algorithms for radiation scatter cameras typically focus on improving image quality. However, with scatter cameras being developed for non-proliferation applications, there is a need for not only source localization but also source identification. This work outlines a modified stochastic origin ensembles algorithm that provides localized spectra for all pixels in the image. We demonstrated the technique by performing three experiments with a dual-particle imager that measured various gamma-ray and neutron sources simultaneously. We showed that we could isolate the peaks from 22Na and 137Cs and that the energy resolution is maintained in the isolated spectra. To evaluate the spectral isolation of neutrons, a 252Cf source and a PuBe source were measured simultaneously and the reconstruction showed that the isolated PuBe spectrum had a higher average energy and a greater fraction of neutrons at higher energies than the 252Cf. Finally, spectrum isolation was used for an experiment with weapons grade plutonium, 252Cf, and AmBe. The resulting neutron and gamma-ray spectra showed the expected characteristics that could then be used to identify the sources.

Atomically thin noble metal dichalcogenide: a broadband mid-infrared semiconductor.

PubMed

Yu, Xuechao; Yu, Peng; Wu, Di; Singh, Bahadur; Zeng, Qingsheng; Lin, Hsin; Zhou, Wu; Lin, Junhao; Suenaga, Kazu; Liu, Zheng; Wang, Qi Jie

2018-04-18

The interest in mid-infrared technologies surrounds plenty of important optoelectronic applications ranging from optical communications, biomedical imaging to night vision cameras, and so on. Although narrow bandgap semiconductors, such as Mercury Cadmium Telluride and Indium Antimonide, and quantum superlattices based on inter-subband transitions in wide bandgap semiconductors, have been employed for mid-infrared applications, it remains a daunting challenge to search for other materials that possess suitable bandgaps in this wavelength range. Here, we demonstrate experimentally for the first time that two-dimensional (2D) atomically thin PtSe 2 has a variable bandgap in the mid-infrared via layer and defect engineering. Here, we show that bilayer PtSe 2 combined with defects modulation possesses strong light absorption in the mid-infrared region, and we realize a mid-infrared photoconductive detector operating in a broadband mid-infrared range. Our results pave the way for atomically thin 2D noble metal dichalcogenides to be employed in high-performance mid-infrared optoelectronic devices.

Detector optimization for hand-held CsI(Tl)/HgI{sub 2} gamma-ray scintillation spectrometer applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Y.J.; Patt, B.E.; Iwanczyk, J.S.

Gamma-ray spectrometers using mercuric iodide (HgI{sub 2}) photodetectors (PDs) coupled with CsI(Tl) scintillators have shown excellent energy resolutions and high detection efficiency at room temperature. Additionally HgI{sub 2} semiconductor PDs allow for extreme miniaturization of the detector packaging compared with photomultiplier tube (PMT) based detectors. These advantages make possible the construction of a new generation of hand-held gamma-ray spectrometers. Studies of detector optimization for this application have been undertaken. Several contact materials including hydrogen and semi-transparent metal films have been evaluated and compared for their performances and long term stability. In order to provide higher gamma-ray detection efficiency (i.e., largermore » scintillator volume), but without causing significant degradation of the excellent response achieved with the matched scintillator/PD interface, the scintillator/PD configuration has been studied. A Monte Carlo simulation model has been developed so that the spectral shape can be predicted for various scintillator shapes and surface treatments.« less

[Diagnostic use of positron emission tomography in France: from the coincidence gamma-camera to mobile hybrid PET/CT devices].

PubMed

Talbot, Jean-Noël

2010-11-01

Positron emission tomography (PET) is a well-established medical imaging method. PET is increasingly used for diagnostic purposes, especially in oncology. The most widely used radiopharmaceutical is FDG, a glucose analogue. Other radiopharmaceuticals have recently been registered or are in development. We outline technical improvements of PET machines during more than a decade of clinical use in France. Even though image quality has improved considerably and PET-CT hybrid machines have emerged, spending per examination has remained remarkably constant. Replacement and maintenance costs have remained in the range of 170-190 Euros per examination since 1997, whether early CDET gamma cameras or the latest time-of-flight PET/CT devices are used. This is mainly due to shorter acquisition times and more efficient use of FDG New reimbursement rates for PET/CT are needed in France in order to favor regular acquisition of state-of-the-art devices. One major development is the coupling of PET and MR imaging.

Evaluation of a gamma camera system for the RITS-6 accelerator using the self-magnetic pinch diode

NASA Astrophysics Data System (ADS)

Webb, Timothy J.; Kiefer, Mark L.; Gignac, Raymond; Baker, Stuart A.

2015-08-01

The self-magnetic pinch (SMP) diode is an intense radiographic source fielded on the Radiographic Integrated Test Stand (RITS-6) accelerator at Sandia National Laboratories in Albuquerque, NM. The accelerator is an inductive voltage adder (IVA) that can operate from 2-10 MV with currents up to 160 kA (at 7 MV). The SMP diode consists of an annular cathode separated from a flat anode, holding the bremsstrahlung conversion target, by a vacuum gap. Until recently the primary imaging diagnostic utilized image plates (storage phosphors) which has generally low DQE at these photon energies along with other problems. The benefits of using image plates include a high-dynamic range, good spatial resolution, and ease of use. A scintillator-based X-ray imaging system or "gamma camera" has been fielded in front of RITS and the SMP diode which has been able to provide vastly superior images in terms of signal-to-noise with similar resolution and acceptable dynamic range.

System of Programmed Modules for Measuring Photographs with a Gamma-Telescope

NASA Technical Reports Server (NTRS)

Averin, S. A.; Veselova, G. V.; Navasardyan, G. V.

1978-01-01

Physical experiments using tracking cameras resulted in hundreds of thousands of stereo photographs of events being received. To process such a large volume of information, automatic and semiautomatic measuring systems are required. At the Institute of Space Research of the Academy of Science of the USSR, a system for processing film information from the spark gamma-telescope was developed. The system is based on a BPS-75 projector in line with the minicomputer Elektronika 1001. The report describes this system. The various computer programs available to the operators are discussed.

A Robotic arm for optical and gamma radwaste inspection

NASA Astrophysics Data System (ADS)

Russo, L.; Cosentino, L.; Pappalardo, A.; Piscopo, M.; Scirè, C.; Scirè, S.; Vecchio, G.; Muscato, G.; Finocchiaro, P.

2014-12-01

We propose Radibot, a simple and cheap robotic arm for remote inspection, which interacts with the radwaste environment by means of a scintillation gamma detector and a video camera representing its light (< 1 kg) payload. It moves vertically thanks to a crane, while the other three degrees of freedom are obtained by means of revolute joints. A dedicated algorithm allows to automatically choose the best kinematics in order to reach a graphically selected position, while still allowing to fully drive the arm by means of a standard videogame joypad.

Comment on 'Imaging of prompt gamma rays emitted during delivery of clinical proton beams with a Compton camera: feasibility studies for range verification'.

PubMed

Sitek, Arkadiusz

2016-12-21

The origin ensemble (OE) algorithm is a new method used for image reconstruction from nuclear tomographic data. The main advantage of this algorithm is the ease of implementation for complex tomographic models and the sound statistical theory. In this comment, the author provides the basics of the statistical interpretation of OE and gives suggestions for the improvement of the algorithm in the application to prompt gamma imaging as described in Polf et al (2015 Phys. Med. Biol. 60 7085).

Comment on ‘Imaging of prompt gamma rays emitted during delivery of clinical proton beams with a Compton camera: feasibility studies for range verification’

NASA Astrophysics Data System (ADS)

Sitek, Arkadiusz

2016-12-01

The origin ensemble (OE) algorithm is a new method used for image reconstruction from nuclear tomographic data. The main advantage of this algorithm is the ease of implementation for complex tomographic models and the sound statistical theory. In this comment, the author provides the basics of the statistical interpretation of OE and gives suggestions for the improvement of the algorithm in the application to prompt gamma imaging as described in Polf et al (2015 Phys. Med. Biol. 60 7085).

Inherent overload protection for the series resonant converter

NASA Technical Reports Server (NTRS)

King, R. J.; Stuart, T. A.

1983-01-01

The overload characteristics of the full bridge series resonant power converter are considered. This includes analyses of the two most common control methods presently in use. The first of these uses a current zero crossing detector to synchronize the control signals and is referred to as the alpha controller. The second is driven by a voltage controlled oscillator and is referred to as the gamma controller. It is shown that the gamma controller has certain reliability advantages in that it can be designed with inherent short circuit protection. Experimental results are included for an 86 kHz converter using power metal-oxide-semiconductor field-effect transistors (MOSFETs).

Harsh-Environment Solid-State Gamma Detector for Down-hole Gas and Oil Exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peter Sandvik; Stanislav Soloviev; Emad Andarawis

2007-08-10

The goal of this program was to develop a revolutionary solid-state gamma-ray detector suitable for use in down-hole gas and oil exploration. This advanced detector would employ wide-bandgap semiconductor technology to extend the gamma sensor's temperature capability up to 200 C as well as extended reliability, which significantly exceeds current designs based on photomultiplier tubes. In Phase II, project tasks were focused on optimization of the final APD design, growing and characterizing the full scintillator crystals of the selected composition, arranging the APD device packaging, developing the needed optical coupling between scintillator and APD, and characterizing the combined elements asmore » a full detector system preparing for commercialization. What follows is a summary report from the second 18-month phase of this program.« less

Radiation tolerant 1 micron CMOS technology

NASA Astrophysics Data System (ADS)

Crevel, P.; Rodde, K.

1991-03-01

Starting from a standard one micron Complementary Metal Oxide Semiconductor (CMOS) for high density, low power memory applications, the degree of radiation tolerance of the baseline process is evaluated. Implemented process modifications to improve latchup sensitivity under heavy ion irradiation as well as total dose effects without changing layout rules are described. By changing doping profiles in Metal Nitride Oxide Semiconductors (MNOS) and P-channel MOS (PMOS) device regions, it is possible to guarantee data sheet specification of a 64 K low power static RAM for total gamma dose up to 35 krad (Si) (and even higher values for the gate array family) without latch up for Linear Energy Transfer LET up to 115 MeV/(mg/cm squared).

Monitoring the distribution of prompt gamma rays in boron neutron capture therapy using a multiple-scattering Compton camera: A Monte Carlo simulation study

NASA Astrophysics Data System (ADS)

Lee, Taewoong; Lee, Hyounggun; Lee, Wonho

2015-10-01

This study evaluated the use of Compton imaging technology to monitor prompt gamma rays emitted by 10B in boron neutron capture therapy (BNCT) applied to a computerized human phantom. The Monte Carlo method, including particle-tracking techniques, was used for simulation. The distribution of prompt gamma rays emitted by the phantom during irradiation with neutron beams is closely associated with the distribution of the boron in the phantom. Maximum likelihood expectation maximization (MLEM) method was applied to the information obtained from the detected prompt gamma rays to reconstruct the distribution of the tumor including the boron uptake regions (BURs). The reconstructed Compton images of the prompt gamma rays were combined with the cross-sectional images of the human phantom. Quantitative analysis of the intensity curves showed that all combined images matched the predetermined conditions of the simulation. The tumors including the BURs were distinguishable if they were more than 2 cm apart.

Investigation to optimize the energy resolution and efficiency of cadmium(zinc)telluride for photon measurements

NASA Astrophysics Data System (ADS)

Kim, Hadong

While the investigations of the Cd(Zn)Te characteristics were completed, a new method to make arbitrary anode shapes, without the troublesome shadow mask technique, was found. With this technique, the two-anode geometry Cd(Zn)Te detector was introduced and tested. The semiconductor performance of the two-anode geometry detectors for the incoming gamma rays of 241Am, 57Co, and 137Cs were compared to the responses of the planar device. The very promising photon energy resolutions of 9.3 and 5.4% FWHM were obtained with the two-anode geometry detector for the gamma rays energies of 122 keV and 662 keV, respectively, while no discernible full energy peaks were apparent with the planar detector. Several simulation programs that are very easy to handle were developed as useful tools for investigating the complicated gamma ray pulse height distributions, which were due to the energy deposition events inside the semiconductors. Comparisons to the known values and with the results from other application programs, validated the information obtained from the simulation programs, which were developed during this research effort. A graphical user interface (GUI) was designed for the user's convenience in order to enter the required input parameters for the specific requirements of each simulation programs. The idealized noise free spectra for the planar detector and for the small pixel geometry detector were successfully obtained by applying Monte Carlo techniques.

Deep-Sea Video Cameras Without Pressure Housings

NASA Technical Reports Server (NTRS)

Cunningham, Thomas

2004-01-01

Underwater video cameras of a proposed type (and, optionally, their light sources) would not be housed in pressure vessels. Conventional underwater cameras and their light sources are housed in pods that keep the contents dry and maintain interior pressures of about 1 atmosphere (.0.1 MPa). Pods strong enough to withstand the pressures at great ocean depths are bulky, heavy, and expensive. Elimination of the pods would make it possible to build camera/light-source units that would be significantly smaller, lighter, and less expensive. The depth ratings of the proposed camera/light source units would be essentially unlimited because the strengths of their housings would no longer be an issue. A camera according to the proposal would contain an active-pixel image sensor and readout circuits, all in the form of a single silicon-based complementary metal oxide/semiconductor (CMOS) integrated- circuit chip. As long as none of the circuitry and none of the electrical leads were exposed to seawater, which is electrically conductive, silicon integrated- circuit chips could withstand the hydrostatic pressure of even the deepest ocean. The pressure would change the semiconductor band gap by only a slight amount . not enough to degrade imaging performance significantly. Electrical contact with seawater would be prevented by potting the integrated-circuit chip in a transparent plastic case. The electrical leads for supplying power to the chip and extracting the video signal would also be potted, though not necessarily in the same transparent plastic. The hydrostatic pressure would tend to compress the plastic case and the chip equally on all sides; there would be no need for great strength because there would be no need to hold back high pressure on one side against low pressure on the other side. A light source suitable for use with the camera could consist of light-emitting diodes (LEDs). Like integrated- circuit chips, LEDs can withstand very large hydrostatic pressures. If power-supply regulators or filter capacitors were needed, these could be attached in chip form directly onto the back of, and potted with, the imager chip. Because CMOS imagers dissipate little power, the potting would not result in overheating. To minimize the cost of the camera, a fixed lens could be fabricated as part of the plastic case. For improved optical performance at greater cost, an adjustable glass achromatic lens would be mounted in a reservoir that would be filled with transparent oil and subject to the full hydrostatic pressure, and the reservoir would be mounted on the case to position the lens in front of the image sensor. The lens would by adjusted for focus by use of a motor inside the reservoir (oil-filled motors already exist).

Highlights of recent results from the VERITAS gamma-ray observatory

NASA Astrophysics Data System (ADS)

Fortson, Lucy; VERITAS Collaboration

2016-05-01

VERITAS is a major ground-based gamma-ray observatory comprising an array of four 12 meter air Cherenkov telescopes operating at the Fred Lawrence Whipple Observatory near Tucson, Arizona. Data taking has continued from 2007 with a major camera upgrade completed in 2012 resulting in the current sensitivity to very-high-energy (VHE) gamma rays between 85 GeV and 30 TeV. VERITAS has detected 54 sources (half of which have been discoveries) leading to many significant contributions to the field of VHE astronomy. These proceedings highlight some of the more recent VERITAS results from the blazar and galactic observing programs as well as measurements of the cosmic-ray electron spectrum, constraints on dark matter and a follow-up program for astrophysical neutrinos.

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, R. G.; Byrum, K.; Drake, G.; Funk, S.; Otte, N.; Smith, A.; Tajima, H.; Williams, D.

2009-05-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. It is being designed to achieve a significant improvement in sensitivity compared to current Imaging Air Cherenkov Telescope (IACT) Arrays. One of the main requirements in order that AGIS fulfills this goal will be to achieve higher angular resolution than current IACTs. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel size is reduced to 0.05 deg, i.e. two to three times smaller than for current IACT cameras. Here we present results from testing of alternatives being considered for AGIS, including both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs).

High-performance camera module for fast quality inspection in industrial printing applications

NASA Astrophysics Data System (ADS)

Fürtler, Johannes; Bodenstorfer, Ernst; Mayer, Konrad J.; Brodersen, Jörg; Heiss, Dorothea; Penz, Harald; Eckel, Christian; Gravogl, Klaus; Nachtnebel, Herbert

2007-02-01

Today, printing products which must meet highest quality standards, e.g., banknotes, stamps, or vouchers, are automatically checked by optical inspection systems. Typically, the examination of fine details of the print or security features demands images taken from various perspectives, with different spectral sensitivity (visible, infrared, ultraviolet), and with high resolution. Consequently, the inspection system is equipped with several cameras and has to cope with an enormous data rate to be processed in real-time. Hence, it is desirable to move image processing tasks into the camera to reduce the amount of data which has to be transferred to the (central) image processing system. The idea is to transfer relevant information only, i.e., features of the image instead of the raw image data from the sensor. These features are then further processed. In this paper a color line-scan camera for line rates up to 100 kHz is presented. The camera is based on a commercial CMOS (complementary metal oxide semiconductor) area image sensor and a field programmable gate array (FPGA). It implements extraction of image features which are well suited to detect print flaws like blotches of ink, color smears, splashes, spots and scratches. The camera design and several image processing methods implemented on the FPGA are described, including flat field correction, compensation of geometric distortions, color transformation, as well as decimation and neighborhood operations.

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerología Department of Nuclear Medicine

NASA Astrophysics Data System (ADS)

Ávila, O.; Torres-Ulloa, C. L.; Medina, L. A.; Trujillo-Zamudio, F. E.; de Buen, I. Gamboa; Buenfil, A. E.; Brandan, M. E.

2010-12-01

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerología, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with 137Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrología, to known 137Cs gamma radiation air kerma. Radionuclides considered for this study are 131I, 18F, 67Ga, 99mTc, 111In, 201Tl and 137Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placed during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with 131I and 137Cs. High dose values were found at the waste storage room, outside corridor of 137Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the 137Cs brachytherapy corridor is equal to (18.51±0.02)×10-3 mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05±0.03)×10-3 mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).

Development of compact Compton camera for 3D image reconstruction of radioactive contamination

NASA Astrophysics Data System (ADS)

Sato, Y.; Terasaka, Y.; Ozawa, S.; Nakamura Miyamura, H.; Kaburagi, M.; Tanifuji, Y.; Kawabata, K.; Torii, T.

2017-11-01

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the large tsunami caused by the Great East Japan Earthquake of March 11, 2011. Very large amounts of radionuclides were released from the damaged plant. Radiation distribution measurements inside FDNPS buildings are indispensable to execute decommissioning tasks in the reactor buildings. We have developed a compact Compton camera to measure the distribution of radioactive contamination inside the FDNPS buildings three-dimensionally (3D). The total weight of the Compton camera is lower than 1.0 kg. The gamma-ray sensor of the Compton camera employs Ce-doped GAGG (Gd3Al2Ga3O12) scintillators coupled with a multi-pixel photon counter. Angular correction of the detection efficiency of the Compton camera was conducted. Moreover, we developed a 3D back-projection method using the multi-angle data measured with the Compton camera. We successfully observed 3D radiation images resulting from the two 137Cs radioactive sources, and the image of the 9.2 MBq source appeared stronger than that of the 2.7 MBq source.

STS-37 Breakfast / Ingress / Launch & ISO Camera Views

NASA Technical Reports Server (NTRS)

1991-01-01

The primary objective of the STS-37 mission was to deploy the Gamma Ray Observatory. The mission was launched at 9:22:44 am on April 5, 1991, onboard the space shuttle Atlantis. The mission was led by Commander Steven Nagel. The crew was Pilot Kenneth Cameron and Mission Specialists Jerry Ross, Jay Apt, and Linda Godwing. This videotape shows the crew having breakfast on the launch day, with the narrator introducing them. It then shows the crew's final preparations and the entry into the shuttle, while the narrator gives information about each of the crew members. The countdown and launch is shown including the shuttle separation from the solid rocket boosters. The launch is reshown from 17 different camera views. Some of the other camera views were in black and white.

A data acquisition system for coincidence imaging using a conventional dual head gamma camera

NASA Astrophysics Data System (ADS)

Lewellen, T. K.; Miyaoka, R. S.; Jansen, F.; Kaplan, M. S.

1997-06-01

A low cost data acquisition system (DAS) was developed to acquire coincidence data from an unmodified General Electric Maxxus dual head scintillation camera. A high impedance pick-off circuit provides position and energy signals to the DAS without interfering with normal camera operation. The signals are pulse-clipped to reduce pileup effects. Coincidence is determined with fast timing signals derived from constant fraction discriminators. A charge-integrating FERA 16 channel ADC feeds position and energy data to two CAMAC FERA memories operated as ping-pong buffers. A Macintosh PowerPC running Labview controls the system and reads the CAMAC memories. A CAMAC 12-channel scaler records singles and coincidence rate data. The system dead-time is approximately 10% at a coincidence rate of 4.0 kHz.

Model analysis for the MAGIC telescope

NASA Astrophysics Data System (ADS)

Mazin, D.; Bigongiari, C.; Goebel, F.; Moralejo, A.; Wittek, W.

The MAGIC Collaboration operates the 17m imaging Cherenkov telescope on the Canary island La Palma. The main goal of the experiment is an energy threshold below 100 GeV for primary gamma rays. The new analysis technique (model analysis) takes advantage of the high resolution (both in space and time) camera by fitting the averaged expected templates of the shower development to the measured shower images in the camera. This approach allows to recognize and reconstruct images just above the level of the night sky background light fluctuations. Progress and preliminary results of the model analysis technique will be presented.

AIRWAY RETENTION OF MATERIALS OF DIFFERENT SOLUBILITY FOLLOWING LOCAL INTRABRONCHIAL DEPOSITION IN DOGS

EPA Science Inventory

We used a gamma camera to monitor the retention and clearance of radiolabeled human serum albumin (HSA), a water-soluble material with molecular weight of 66,000 Daltons, and radiolabeled sulfur colloid (SC), an insoluble submicron (0.22 microm) particle, following localized depo...

Low Noise Double-Sided Silicon Strip Detector for Multiple-Compton Gamma-ray Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tajima, Hiroyasu

2002-12-03

A Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in an energy band 0.1-20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of the SMCT is the high energy resolution that is crucial for high angular resolution and high background rejection capability. We have developed prototype modules for a low noise Double-sided Silicon Strip Detector (DSSD) system which is an essential element of the SMCT. The geometry of the DSSD is optimized to achieve the lowest noise possible. A new front-end VLSI device optimized for low noise operationmore » is also developed. We report on the design and test results of the prototype system. We have reached an energy resolution of 1.3 keV (FWHM) for 60 keV and 122 keV at 0 C.« less

Improving the radiation hardness of graphene field effect transistors

DOE PAGES

Alexandrou, Konstantinos; Masurkar, Amrita; Edrees, Hassan; ...

2016-10-11

Ionizing radiation poses a significant challenge to the operation and reliability of conventional silicon-based devices. In this paper, we report the effects of gamma radiation on graphene field-effect transistors (GFETs), along with a method to mitigate those effects by developing a radiation-hardened version of our back-gated GFETs. We demonstrate that activated atmospheric oxygen from the gamma ray interaction with air damages the semiconductor device, and damage to the substrate contributes additional threshold voltage instability. Our radiation-hardened devices, which have protection against these two effects, exhibit minimal performance degradation, improved stability, and significantly reduced hysteresis after prolonged gamma radiation exposure. Finally,more » we believe this work provides an insight into graphene's interactions with ionizing radiation that could enable future graphene-based electronic devices to be used for space, military, and other radiation-sensitive applications.« less

Improving the radiation hardness of graphene field effect transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexandrou, Konstantinos; Masurkar, Amrita; Edrees, Hassan

Ionizing radiation poses a significant challenge to the operation and reliability of conventional silicon-based devices. In this paper, we report the effects of gamma radiation on graphene field-effect transistors (GFETs), along with a method to mitigate those effects by developing a radiation-hardened version of our back-gated GFETs. We demonstrate that activated atmospheric oxygen from the gamma ray interaction with air damages the semiconductor device, and damage to the substrate contributes additional threshold voltage instability. Our radiation-hardened devices, which have protection against these two effects, exhibit minimal performance degradation, improved stability, and significantly reduced hysteresis after prolonged gamma radiation exposure. Finally,more » we believe this work provides an insight into graphene's interactions with ionizing radiation that could enable future graphene-based electronic devices to be used for space, military, and other radiation-sensitive applications.« less

Induced radioactivity in the forward shielding and semiconductor tracker of the ATLAS detector.

PubMed

Bĕdajánek, I; Linhart, V; Stekl, I; Pospísil, S; Kolros, A; Kovalenko, V

2005-01-01

The radioactivity induced in the forward shielding, copper collimator and semiconductor tracker modules of the ATLAS detector has been studied. The ATLAS detector is a long-term experiment which, during operation, will require to have service and access to all of its parts and components. The radioactivity induced in the forward shielding was calculated by Monte Carlo methods based on GEANT3 software tool. The results show that the equivalent dose rates on the outer surface of the forward shielding are very low (at most 0.038 microSv h(-1)). On the other hand, the equivalent dose rates are significantly higher on the inner surface of the forward shielding (up to 661 microSv h(-1)) and, especially, at the copper collimator close to the beampipe (up to 60 mSv h(-1)). The radioactivity induced in the semiconductor tracker modules was studied experimentally. The module was activated by neutrons in a training nuclear reactor and the delayed gamma ray spectra were measured. From these measurements, the equivalent dose rate on the surface of the semiconductor tracker module was estimated to be < 100 microSv h(-1) after 100 d of Large Hadron Collider (LHC) operation and 10 d of cooling.

Superficial vessel reconstruction with a multiview camera system

PubMed Central

Marreiros, Filipe M. M.; Rossitti, Sandro; Karlsson, Per M.; Wang, Chunliang; Gustafsson, Torbjörn; Carleberg, Per; Smedby, Örjan

2016-01-01

Abstract. We aim at reconstructing superficial vessels of the brain. Ultimately, they will serve to guide the deformation methods to compensate for the brain shift. A pipeline for three-dimensional (3-D) vessel reconstruction using three mono-complementary metal-oxide semiconductor cameras has been developed. Vessel centerlines are manually selected in the images. Using the properties of the Hessian matrix, the centerline points are assigned direction information. For correspondence matching, a combination of methods was used. The process starts with epipolar and spatial coherence constraints (geometrical constraints), followed by relaxation labeling and an iterative filtering where the 3-D points are compared to surfaces obtained using the thin-plate spline with decreasing relaxation parameter. Finally, the points are shifted to their local centroid position. Evaluation in virtual, phantom, and experimental images, including intraoperative data from patient experiments, shows that, with appropriate camera positions, the error estimates (root-mean square error and mean error) are ∼1  mm. PMID:26759814

Design criteria for a high energy Compton Camera and possible application to targeted cancer therapy

NASA Astrophysics Data System (ADS)

Conka Nurdan, T.; Nurdan, K.; Brill, A. B.; Walenta, A. H.

2015-07-01

The proposed research focuses on the design criteria for a Compton Camera with high spatial resolution and sensitivity, operating at high gamma energies and its possible application for molecular imaging. This application is mainly on the detection and visualization of the pharmacokinetics of tumor targeting substances specific for particular cancer sites. Expected high resolution (< 0.5 mm) permits monitoring the pharmacokinetics of labeled gene constructs in vivo in small animals with a human tumor xenograft which is one of the first steps in evaluating the potential utility of a candidate gene. The additional benefit of high sensitivity detection will be improved cancer treatment strategies in patients based on the use of specific molecules binding to cancer sites for early detection of tumors and identifying metastasis, monitoring drug delivery and radionuclide therapy for optimum cell killing at the tumor site. This new technology can provide high resolution, high sensitivity imaging of a wide range of gamma energies and will significantly extend the range of radiotracers that can be investigated and used clinically. The small and compact construction of the proposed camera system allows flexible application which will be particularly useful for monitoring residual tumor around the resection site during surgery. It is also envisaged as able to test the performance of new drug/gene-based therapies in vitro and in vivo for tumor targeting efficacy using automatic large scale screening methods.

Evaluation of gamma dose effect on PIN photodiode using analytical model

NASA Astrophysics Data System (ADS)

Jafari, H.; Feghhi, S. A. H.; Boorboor, S.

2018-03-01

The PIN silicon photodiodes are widely used in the applications which may be found in radiation environment such as space mission, medical imaging and non-destructive testing. Radiation-induced damage in these devices causes to degrade the photodiode parameters. In this work, we have used new approach to evaluate gamma dose effects on a commercial PIN photodiode (BPX65) based on an analytical model. In this approach, the NIEL parameter has been calculated for gamma rays from a 60Co source by GEANT4. The radiation damage mechanisms have been considered by solving numerically the Poisson and continuity equations with the appropriate boundary conditions, parameters and physical models. Defects caused by radiation in silicon have been formulated in terms of the damage coefficient for the minority carriers' lifetime. The gamma induced degradation parameters of the silicon PIN photodiode have been analyzed in detail and the results were compared with experimental measurements and as well as the results of ATLAS semiconductor simulator to verify and parameterize the analytical model calculations. The results showed reasonable agreement between them for BPX65 silicon photodiode irradiated by 60Co gamma source at total doses up to 5 kGy under different reverse voltages.

Total-dose radiation effects data for semiconductor devices. 1985 Supplement. Volume 2, part B

NASA Technical Reports Server (NTRS)

Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

1986-01-01

Steady-state, total-dose radiation test data are provided in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. The document is in two volumes: Volume 1 provides data on diodes, bipolar transistors, field effect transistors, and miscellaneous semiconductor types, and Volume 2 (Parts A and B) provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done steady-state 2.5-MeV electron beam. However, some radiation exposures were made with a Cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose. All data were generated in support of NASA space programs by the JPL Radiation Effects and Testing Group (514).

Gamma-ray detector guidance of breast cancer therapy

NASA Astrophysics Data System (ADS)

Ravi, Ananth

2009-12-01

Breast cancer is the most common form of cancer in women. Over 75% of breast cancer patients are eligible for breast conserving therapy. Breast conserving therapy involves a lumpectomy to excise the gross tumour, followed by adjuvant radiation therapy to eradicate residual microscopic disease. Recent advances in the understanding of breast cancer biology and recurrence have presented the opportunity to improve breast conserving therapy techniques. This thesis has explored the potential of gamma-ray detecting technology to improve guidance of both surgical and adjuvant radiation therapy aspects of breast conserving therapy. The task of accurately excising the gross tumour during breast conserving surgery (BCS) is challenging, due to the limited guidance currently available to surgeons. Radioimmuno guided surgery (RIGS) has been investigated to determine its potential to delineate the gross tumour intraoperatively. The effects of varying a set of user controllable parameters on the ability of RIGS to detect and delineate model breast tumours was determined. The parameters studied were: Radioisotope, blood activity concentration, collimator height and energy threshold. The most sensitive combination of parameters was determined to be an 111Indium labelled radiopharmaceutical with a gamma-ray detecting probe collimated to a height of 5 mm and an energy threshold at the Compton backscatter peak. Using these parameters it was found that, for the breast tumour model used, the minimum tumour-to-background ratio required to delineate the tumour edge accurately was 5.2+/-0.4 at a blood activity concentration of 5 kBq/ml. Permanent breast seed implantation (PBSI) is a form of accelerated partial breast irradiation that dramatically reduces the treatment burden of adjuvant radiation therapy on patients. Unfortunately, it is currently difficult to localize the implanted brachytherapy seeds, making it difficult to perform a correction in the event that seeds have been misplaced. One method to provide intraoperative seed localization is through the use of a gamma-camera system. Monte Carlo simulations were conducted of a Cadmium Zinc Telluride (CZT) gamma-camera system and a realistic model of a breast with 3 layers of seeds distributed according to the pre-implant treatment plan of a typical patient. The simulations showed that a gamma-camera was able to localize the seeds with a maximum error of 2.0 mm within 20 seconds. An experimental prototype was designed and constructed to validate these promising Monte Carlo results. Using a 64 pixel linear array CZT detector fitted with a custom built brass collimator, images were acquired of a physical phantom similar to the model used in the Monte Carlo simulations. The experimental prototype was able to reliably detect the seeds within 30 seconds with a median error in localization of 1 mm. The results from this thesis suggest that gamma-ray detecting technology may be able to provide significant improvements in guidance of breast cancer therapies and, thus, potentially improved therapeutic outcomes.

Gamma-ray detector employing scintillators coupled to semiconductor drift photodetectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwanczyk, Jan S.; Patt, Bradley E.

Radiation detectors according to one embodiment of the invention are implemented using scintillators combined with a semiconductor drift photodetectors wherein the components are specifically constructed in terms of their geometry, dimensions, and arrangement so that the scintillator decay time and drift time in the photodetector pairs are matched in order to achieve a greater signal-to-noise ratio. The detectors may include electronics for amplification of electrical signals produced by the silicon drift photodetector, the amplification having a shaping time optimized with respect to the decay time of the scintillator and time spread of the signal in the silicon drift photodetector tomore » substantially maximize the ratio of the signal to the electronic noise.« less

Long-term changes in open field activity of male mice irradiated with low levels of gamma rays at late stage of development.

PubMed

Minamisawa, T; Hirokaga, K

1996-06-01

The open field activity of first generation (F1) hybrid male C57BL/6 x C3H mice irradiated with gamma-rays on the 14th day of gestation was studied at the following ages: 6-7 months, 12-13 months and 19-20 months. Doses were 0.1 Gy or 0.2 Gy. Open field activity was recorded with a camera. The camera output signal was recorded every sec through an A/D converter to a personal computer. The field was divided into 25 units of 8 cm square. All recordings were continuous for 60 min. The time which the 0.2-Gy group recorded at 6-7 months, spent in the 4 squares in the corner fields was high in comparison with the control group at the same age. The walking distance of the 0.1-Gy group recorded at 12-13 months was longer than that for the age matched control group. No effect of radiation was found on any of the behaviors observed and recorded at 19-20 months. The results demonstrate that exposure to low levels of gamma-rays on the 14th day of gestation results in behavioral changes, which occur at 6-7 and 12-13 months but not 19-20 months.

Multiple-frame IR photo-recorder KIT-3M

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roos, E; Wilkins, P; Nebeker, N

2006-05-15

This paper reports the experimental results of a high-speed multi-frame infrared camera which has been developed in Sarov at VNIIEF. Earlier [1] we discussed the possibility of creation of the multi-frame infrared radiation photo-recorder with framing frequency about 1 MHz. The basis of the photo-recorder is a semiconductor ionization camera [2, 3], which converts IR radiation of spectral range 1-10 micrometers into a visible image. Several sequential thermal images are registered by using the IR converter in conjunction with a multi-frame electron-optical camera. In the present report we discuss the performance characteristics of a prototype commercial 9-frame high-speed IR photo-recorder.more » The image converter records infrared images of thermal fields corresponding to temperatures ranging from 300 C to 2000 C with an exposure time of 1-20 {micro}s at a frame frequency up to 500 KHz. The IR-photo-recorder camera is useful for recording the time evolution of thermal fields in fast processes such as gas dynamics, ballistics, pulsed welding, thermal processing, automotive industry, aircraft construction, in pulsed-power electric experiments, and for the measurement of spatial mode characteristics of IR-laser radiation.« less

Measuring the circular motion of small objects using laser stroboscopic images.

PubMed

Wang, Hairong; Fu, Y; Du, R

2008-01-01

Measuring the circular motion of a small object, including its displacement, speed, and acceleration, is a challenging task. This paper presents a new method for measuring repetitive and/or nonrepetitive, constant speed and/or variable speed circular motion using laser stroboscopic images. Under stroboscopic illumination, each image taken by an ordinary camera records multioutlines of an object in motion; hence, processing the stroboscopic image will be able to extract the motion information. We built an experiment apparatus consisting of a laser as the light source, a stereomicroscope to magnify the image, and a normal complementary metal oxide semiconductor camera to record the image. As the object is in motion, the stroboscopic illumination generates a speckle pattern on the object that can be recorded by the camera and analyzed by a computer. Experimental results indicate that the stroboscopic imaging is stable under various conditions. Moreover, the characteristics of the motion, including the displacement, the velocity, and the acceleration can be calculated based on the width of speckle marks, the illumination intensity, the duty cycle, and the sampling frequency. Compared with the popular high-speed camera method, the presented method may achieve the same measuring accuracy, but with much reduced cost and complexity.

Performance analysis and enhancement for visible light communication using CMOS sensors

NASA Astrophysics Data System (ADS)

Guan, Weipeng; Wu, Yuxiang; Xie, Canyu; Fang, Liangtao; Liu, Xiaowei; Chen, Yingcong

2018-03-01

Complementary Metal-Oxide-Semiconductor (CMOS) sensors are widely used in mobile-phone and cameras. Hence, it is attractive if these camera can be used as the receivers of visible light communication (VLC). Using the rolling shutter mechanism can increase the data rate of VLC based on CMOS camera, and different techniques have been proposed to improve the demodulation of the rolling shutter mechanism. However, these techniques are too complexity. In this work, we demonstrate and analyze the performance of the VLC link using CMOS camera for different LED luminaires for the first time in our knowledge. Experimental evaluation to compare their bit-error-rate (BER) performances and demodulation are also performed, and it can be summarized that just need to change the LED luminaire with more uniformity light output, the blooming effect would not exist; which not only can reduce the complexity of the demodulation but also enhance the communication quality. In addition, we propose and demonstrate to use contrast limited adaptive histogram equalization to extend the transmission distance and mitigate the influence of the background noise. And the experimental results show that the BER can be decreased by an order of magnitude by using the proposed method.

Camera-Based Lock-in and Heterodyne Carrierographic Photoluminescence Imaging of Crystalline Silicon Wafers

NASA Astrophysics Data System (ADS)

Sun, Q. M.; Melnikov, A.; Mandelis, A.

2015-06-01

Carrierographic (spectrally gated photoluminescence) imaging of a crystalline silicon wafer using an InGaAs camera and two spread super-bandgap illumination laser beams is introduced in both low-frequency lock-in and high-frequency heterodyne modes. Lock-in carrierographic images of the wafer up to 400 Hz modulation frequency are presented. To overcome the frame rate and exposure time limitations of the camera, a heterodyne method is employed for high-frequency carrierographic imaging which results in high-resolution near-subsurface information. The feasibility of the method is guaranteed by the typical superlinearity behavior of photoluminescence, which allows one to construct a slow enough beat frequency component from nonlinear mixing of two high frequencies. Intensity-scan measurements were carried out with a conventional single-element InGaAs detector photocarrier radiometry system, and the nonlinearity exponent of the wafer was found to be around 1.7. Heterodyne images of the wafer up to 4 kHz have been obtained and qualitatively analyzed. With the help of the complementary lock-in and heterodyne modes, camera-based carrierographic imaging in a wide frequency range has been realized for fundamental research and industrial applications toward in-line nondestructive testing of semiconductor materials and devices.

Nondestructive assessment of the severity of occlusal caries lesions with near-infrared imaging at 1310 nm.

PubMed

Lee, Chulsung; Lee, Dustin; Darling, Cynthia L; Fried, Daniel

2010-01-01

The high transparency of dental enamel in the near-infrared (NIR) at 1310 nm can be exploited for imaging dental caries without the use of ionizing radiation. The objective of this study is to determine whether the lesion contrast derived from NIR imaging in both transmission and reflectance can be used to estimate lesion severity. Two NIR imaging detector technologies are investigated: a new Ge-enhanced complementary metal-oxide-semiconductor (CMOS)-based NIR imaging camera, and an InGaAs focal plane array (FPA). Natural occlusal caries lesions are imaged with both cameras at 1310 nm, and the image contrast between sound and carious regions is calculated. After NIR imaging, teeth are sectioned and examined using polarized light microscopy (PLM) and transverse microradiography (TMR) to determine lesion severity. Lesions are then classified into four categories according to lesion severity. Lesion contrast increases significantly with lesion severity for both cameras (p<0.05). The Ge-enhanced CMOS camera equipped with the larger array and smaller pixels yields higher contrast values compared with the smaller InGaAs FPA (p<0.01). Results demonstrate that NIR lesion contrast can be used to estimate lesion severity.

Nondestructive assessment of the severity of occlusal caries lesions with near-infrared imaging at 1310 nm

PubMed Central

Lee, Chulsung; Lee, Dustin; Darling, Cynthia L.; Fried, Daniel

2010-01-01

The high transparency of dental enamel in the near-infrared (NIR) at 1310 nm can be exploited for imaging dental caries without the use of ionizing radiation. The objective of this study is to determine whether the lesion contrast derived from NIR imaging in both transmission and reflectance can be used to estimate lesion severity. Two NIR imaging detector technologies are investigated: a new Ge-enhanced complementary metal-oxide-semiconductor (CMOS)-based NIR imaging camera, and an InGaAs focal plane array (FPA). Natural occlusal caries lesions are imaged with both cameras at 1310 nm, and the image contrast between sound and carious regions is calculated. After NIR imaging, teeth are sectioned and examined using polarized light microscopy (PLM) and transverse microradiography (TMR) to determine lesion severity. Lesions are then classified into four categories according to lesion severity. Lesion contrast increases significantly with lesion severity for both cameras (p<0.05). The Ge-enhanced CMOS camera equipped with the larger array and smaller pixels yields higher contrast values compared with the smaller InGaAs FPA (p<0.01). Results demonstrate that NIR lesion contrast can be used to estimate lesion severity. PMID:20799842

Nondestructive assessment of the severity of occlusal caries lesions with near-infrared imaging at 1310 nm

NASA Astrophysics Data System (ADS)

Lee, Chulsung; Lee, Dustin; Darling, Cynthia L.; Fried, Daniel

2010-07-01

The high transparency of dental enamel in the near-infrared (NIR) at 1310 nm can be exploited for imaging dental caries without the use of ionizing radiation. The objective of this study is to determine whether the lesion contrast derived from NIR imaging in both transmission and reflectance can be used to estimate lesion severity. Two NIR imaging detector technologies are investigated: a new Ge-enhanced complementary metal-oxide-semiconductor (CMOS)-based NIR imaging camera, and an InGaAs focal plane array (FPA). Natural occlusal caries lesions are imaged with both cameras at 1310 nm, and the image contrast between sound and carious regions is calculated. After NIR imaging, teeth are sectioned and examined using polarized light microscopy (PLM) and transverse microradiography (TMR) to determine lesion severity. Lesions are then classified into four categories according to lesion severity. Lesion contrast increases significantly with lesion severity for both cameras (p<0.05). The Ge-enhanced CMOS camera equipped with the larger array and smaller pixels yields higher contrast values compared with the smaller InGaAs FPA (p<0.01). Results demonstrate that NIR lesion contrast can be used to estimate lesion severity.

Thermoelectric Properties of Lanthanum Sulfide

NASA Technical Reports Server (NTRS)

Wood, C.; Lockwood, R.; Parker, J. B.; Zoltan, A.; Zoltan, L. D.; Danielson, L.; Raag, V.

1987-01-01

Report describes measurement of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall effect in gamma-phase lanthanum sulfide with composition of La3-x S4. Results of study, part of search for high-temperature thermoelectric energy-conversion materials, indicate this sulfide behaves like extrinsic semiconductor over temperature range of 300 to 1,400 K, with degenerate carrier concentration controlled by stoichiometric ratio of La to S.

Analysis of a Statistical Relationship Between Dose and Error Tallies in Semiconductor Digital Integrated Circuits for Application to Radiation Monitoring Over a Wireless Sensor Network

NASA Astrophysics Data System (ADS)

Colins, Karen; Li, Liqian; Liu, Yu

2017-05-01

Mass production of widely used semiconductor digital integrated circuits (ICs) has lowered unit costs to the level of ordinary daily consumables of a few dollars. It is therefore reasonable to contemplate the idea of an engineered system that consumes unshielded low-cost ICs for the purpose of measuring gamma radiation dose. Underlying the idea is the premise of a measurable correlation between an observable property of ICs and radiation dose. Accumulation of radiation-damage-induced state changes or error events is such a property. If correct, the premise could make possible low-cost wide-area radiation dose measurement systems, instantiated as wireless sensor networks (WSNs) with unshielded consumable ICs as nodes, communicating error events to a remote base station. The premise has been investigated quantitatively for the first time in laboratory experiments and related analyses performed at the Canadian Nuclear Laboratories. State changes or error events were recorded in real time during irradiation of samples of ICs of different types in a 60Co gamma cell. From the error-event sequences, empirical distribution functions of dose were generated. The distribution functions were inverted and probabilities scaled by total error events, to yield plots of the relationship between dose and error tallies. Positive correlation was observed, and discrete functional dependence of dose quantiles on error tallies was measured, demonstrating the correctness of the premise. The idea of an engineered system that consumes unshielded low-cost ICs in a WSN, for the purpose of measuring gamma radiation dose over wide areas, is therefore tenable.

Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation

NASA Astrophysics Data System (ADS)

Abdullah, J.; Yahya, R.

2007-05-01

Corrosion under insulation (CUI) on the external wall of steel pipes is a common problem in many types of industrial plants. This is mainly due to the presence of moisture or water in the insulation materials. This type of corrosion can cause failures in areas that are not normally of a primary concern to an inspection program. The failures are often the result of localised corrosion and not general wasting over a large area. These failures can tee catastrophic in nature or at least have an adverse economic effect in terms of downtime and repairs. There are a number of techniques used today for CUI investigations. The main ones are profile radiography, pulse eddy current, ultrasonic spot readings and insulation removal. A new system now available is portable Pipe-CUI-Profiler. The nucleonic system is based on dual-beam gamma-ray absorption technique using Cadmium Zinc Telluride (CdZnTe) semiconductor detectors. The Pipe-CUI-Profiler is designed to inspect pipes of internal diameter 50, 65, 80, 90, 100, 125 and 150 mm. Pipeline of these sizes with aluminium or thin steel sheathing, containing fibreglass or calcium silicate insulation to thickness of 25, 40 and 50 mm can be inspected. The system has proven to be a safe, fast and effective method of inspecting pipe in industrial plant operations. This paper describes the application of gamma-ray techniques and CdZnTe semiconductor detectors in the development of Pipe-CUI-Profiler for non-destructive imaging of corrosion under insulation of steel pipes. Some results of actual pipe testing in large-scale industrial plant will be presented.

Copper crystal lens for medical imaging: first results

NASA Astrophysics Data System (ADS)

Roa, Dante E.; Smither, Robert K.

2001-06-01

A copper crystal lens designed to focus gamma ray energies of 100 to 200 keV has been assembled at Argonne National Laboratory. In particular, the lens has been optimized to focus the 140.6 keV gamma rays from technetium-99 m typically used in radioactive tracers. This new approach to medical imaging relies on crystal diffraction to focus incoming gamma rays in a manner similar to a simple convex lens focusing visible light. The lens is envisioned to be part of an array of lenses that can be used as a complementary technique to gamma cameras for localized scans of suspected tumor regions in the body. In addition, a 2- lens array can be used to scan a woman's breast in search of tumors with no discomfort to the patient. The incoming gamma rays are diffracted by a set of 828 copper crystal cubes arranged in 13 concentric rings, which focus the gamma rays into a very small area on a well-shielded NaI detector. Experiments performance with technetium-99 m and cobalt 57 radioactive sources indicate that a 6-lens array should be capable of detecting sources with (mu) Ci strength.

X-ray shout echoing through space

NASA Astrophysics Data System (ADS)

2004-01-01

a flash of X-rays hi-res Size hi-res: 3991 Kb Credits: ESA, S. Vaughan (University of Leicester) EPIC camera shows the expanding rings caused by a flash of X-rays XMM-Newton's X-ray EPIC camera shows the expanding rings caused by a flash of X-rays scattered by dust in our Galaxy. The X-rays were produced by a powerful gamma-ray burst that took place on 3 December 2003. The slowly fading afterglow of the gamma-ray burst is at the centre of the expanding rings. Other, unrelated, X-ray sources can also be seen. The time since the gamma-ray explosion is shown in each panel in hours. At their largest size, the rings would appear in the sky about five times smaller than the full moon. a flash of X-rays hi-res Size hi-res: 2153 Kb Credits: ESA, S. Vaughan (University of Leicester) EPIC camera shows the expanding rings caused by a flash of X-rays (Please choose "hi-res" version for animation) XMM-Newton's X-ray EPIC camera shows the expanding rings caused by a flash of X-rays scattered by dust in our Galaxy. The X-rays were produced by a powerful gamma-ray burst that took place on 3 December 2003. The slowly fading afterglow of the gamma-ray burst is at the centre of the expanding rings. Other, unrelated, X-ray sources can also be seen. The time since the gamma-ray explosion is shown in each panel in seconds. At their largest size, the rings would appear in the sky about five times smaller than the full moon. This echo forms when the powerful radiation of a gamma-ray burst, coming from far away, crosses a slab of dust in our Galaxy and is scattered by it, like the beam of a lighthouse in clouds. Using the expanding rings to precisely pin-point the location of this dust, astronomers can identify places where new stars and planets are likely to form. On 3 December 2003 ESA's observatory, Integral, detected a burst of gamma rays, lasting about 30 seconds, from the direction of a distant galaxy. Within minutes of the detection, thanks to a sophisticated alert network, many observatories around the world were pointing their instruments at this mysterious source in the sky, named GRB 031203, in the attempt to decipher its nature. Also ESA's X-ray observatory, XMM-Newton, joined the hunt and observed the source in detail, using its on-board European Photon Imaging Camera (EPIC). The fading X-ray emission from GRB 031203 - called the `afterglow' - is clearly seen in XMM-Newton's images. But much more stunning are the two rings, centred on the afterglow, which appear to expand thousand times faster than the speed of light. Dr. Simon Vaughan, of the University of Leicester, United Kingdom, leads an international team of scientists studying GRB 031203. He explains that these rings are what astronomers call an `echo'. They form when the X-rays from the distant gamma-ray burst shine on a layer of dust in our own Galaxy. "The dust scatters some of the X-rays, causing XMM-Newton to observe these rings, much in the same way as fog scatters the light from a car's headlights," said Vaughan. Although the afterglow is the brightest feature seen in XMM-Newton's images, the expanding echo is much more spectacular. "It is like a shout in a cathedral," Vaughan said. "The shout of the gamma-ray burst is louder, but the Galactic reverberation, seen as the rings, is much more beautiful." The rings seem to expand because the X-rays scattered by dust farther from the direction of GRB 031203 take longer to reach us than those hitting the dust closer to the line of sight. However, nothing can move faster than light. "This is precisely what we expect because of the finite speed of light," said Vaughan. "The rate of expansion that we see is just a visual effect." He and his colleagues explain that we see two rings because there are two thin sheets of dust between the source of the gamma-ray burst and Earth, one closer to us creating the wider ring and one further away where the smaller ring is formed. Since they know precisely at what speed the X-ray light travels in space, the team in Leicester have determined accurately the distance to the dust sheets by measuring the size of the expanding rings. The nearest dust sheet is located 2900 light years away and is probably part of the Gum nebula, a bubble of hot gas resulting from many supernova explosions. The other dust layer is about 4500 light years away. Understanding how dust is distributed in our Galaxy is important because dust favours the collapse of cool gas clouds, which can then form stars and planets. Knowing where dust is located helps astronomers to determine where star and planet formation is likely to occur. Expanding X-ray dust scattering rings, such as those around GRB 031203, have never been seen before. Slower-moving rings, caused by a similar effect, have been seen in visible light around a very few exploding stars, mostly supernovae. The expanding rings also provide much needed information on the gamma-ray burst itself. Gamma-ray bursts are the most powerful explosive events in the Universe, but astronomers are still trying to understand the mystery that surrounds their origin. Some occur with the supernova explosion of a massive star when it has used up all of its fuel, although only stars which have lost their outer layers and which collapse to make a black hole seem able to make a gamma-ray burst. The delayed X-rays from the echo of GRB 031203 are very useful because they tell astronomers how bright the burst was in the X-ray spectrum when it went off on 3 December. The only direct data available from that moment are those obtained by ESA's Integral observatory in the gamma-ray range. "XMM-Newton's measurements are thus crucial to better understand the nature of the burst," said Dr. Fred Jansen, XMM-Newton's project scientist. "The more details we gather of the burst, the more we can learn on how black holes are made." Today, ESA's Integral and XMM-Newton observatories provide astronomers with their most powerful facilities for studying gamma-ray bursts. In 2004 a new gamma-ray satellite, called `Swift', will be launched as part of a collaboration between the USA, United Kingdom and Italy. Swift will add to the flotilla of satellites providing fast and accurate locations of gamma-ray bursts on the sky, which can then be followed with XMM-Newton. This will provide even more opportunities for new discoveries in this cutting-edge field. Notes to editors A scientific paper describing this discovery by Dr. Simon Vaughan and his collaborators has been accepted for publication in ``The Astrophysical Journal'' (see http://arxiv.org/abs/astro-ph/0312603). The other members in Vaughan's team are R. Willingale, P. O'Brien, J. Osborne, A. Levan, M. Watson and J. Tedds from the University of Leicester, United Kingdom; J. Reeves from NASA's Goddard Space Flight Center in Greenbelt, USA; D. Watson from the Neils Bohr Institute for Astronomy in Copenhagen, Denmark; M. Santos-Lleo, P. Rodriguez-Pascual and N. Schartel from ESA's XMM-Newton Science Operations Centre in Villafranca, Spain. Figure caption XMM-Newton's X-ray EPIC camera shows the expanding rings caused by a flash of X-rays scattered by dust in our Galaxy. The X-rays were produced by a powerful gamma-ray burst that took place on 3 December 2003. The slowly fading afterglow of the gamma-ray burst is at the centre of the expanding rings. Other, unrelated, X-ray sources can also be seen. The time since the gamma-ray explosion is shown in each panel in hours. At their largest size, the rings would appear in the sky about five times smaller than the full moon. Credit: ESA, S. Vaughan (University of Leicester) Video caption XMM-Newton's X-ray EPIC camera shows the expanding rings caused by a flash of X-rays scattered by dust in our Galaxy. The X-rays were produced by a powerful gamma-ray burst that took place on 3 December 2003. The slowly fading afterglow of the gamma-ray burst is at the centre of the expanding rings. Other, unrelated, X-ray sources can also be seen. The time since the gamma-ray explosion is shown in each panel in seconds. At their largest size, the rings would appear in the sky about five times smaller than the full moon. Credit: ESA, S. Vaughan (University of Leicester) More about XMM-Newton XMM-Newton can detect more X-ray sources than any previous satellite and is helping to solve many cosmic mysteries of the violent Universe, from black holes to the formation of galaxies. It was launched on 10 December 1999, using an Ariane-5 rocket from French Guiana. It is expected to return data for a decade. XMM-Newton's high-tech design uses over 170 wafer-thin cylindrical mirrors spread over three telescopes. Its orbit takes it almost a third of the way to the Moon, so that astronomers can enjoy long, uninterrupted views of celestial objects.

Pulse Mode Light Sensing Using Four-Layer Semiconductor Structures and Their Application in Neural Networks

DTIC Science & Technology

2008-12-01

However, the visual sensation was found to occur in retinal areas distant from the implant [10]. Since the current generated under normal light...electronics could limit the use of the microphotodetector array in retinal stimulation. Alternatively, a thin array, containing 64 electrodes...that passes through the skull and skin. Outside the skull, the device is similar to the retinal stimulators, with a television camera mounted on

Flexible nuclear medicine camera and method of using

DOEpatents

Dilmanian, F.A.; Packer, S.; Slatkin, D.N.

1996-12-10

A nuclear medicine camera and method of use photographically record radioactive decay particles emitted from a source, for example a small, previously undetectable breast cancer, inside a patient. The camera includes a flexible frame containing a window, a photographic film, and a scintillation screen, with or without a gamma-ray collimator. The frame flexes for following the contour of the examination site on the patient, with the window being disposed in substantially abutting contact with the skin of the patient for reducing the distance between the film and the radiation source inside the patient. The frame is removably affixed to the patient at the examination site for allowing the patient mobility to wear the frame for a predetermined exposure time period. The exposure time may be several days for obtaining early qualitative detection of small malignant neoplasms. 11 figs.

View of Scientific Instrument Module to be flown on Apollo 15

NASA Image and Video Library

1971-06-27

S71-2250X (June 1971) --- A close-up view of the Scientific Instrument Module (SIM) to be flown for the first time on the Apollo 15 lunar landing mission. Mounted in a previously vacant sector of the Apollo Service Module (SM), the SIM carries specialized cameras and instrumentation for gathering lunar orbit scientific data. SIM equipment includes a laser altimeter for accurate measurement of height above the lunar surface; a large-format panoramic camera for mapping, correlated with a metric camera and the laser altimeter for surface mapping; a gamma ray spectrometer on a 25-feet extendible boom; a mass spectrometer on a 21-feet extendible boom; X-ray and alpha particle spectrometers; and a subsatellite which will be injected into lunar orbit carrying a particle and magnetometer, and the S-Band transponder.

A gamma beam profile imager for ELI-NP Gamma Beam System

NASA Astrophysics Data System (ADS)

Cardarelli, P.; Paternò, G.; Di Domenico, G.; Consoli, E.; Marziani, M.; Andreotti, M.; Evangelisti, F.; Squerzanti, S.; Gambaccini, M.; Albergo, S.; Cappello, G.; Tricomi, A.; Veltri, M.; Adriani, O.; Borgheresi, R.; Graziani, G.; Passaleva, G.; Serban, A.; Starodubtsev, O.; Variola, A.; Palumbo, L.

2018-06-01

The Gamma Beam System of ELI-Nuclear Physics is a high brilliance monochromatic gamma source based on the inverse Compton interaction between an intense high power laser and a bright electron beam with tunable energy. The source, currently being assembled in Magurele (Romania), is designed to provide a beam with tunable average energy ranging from 0.2 to 19.5 MeV, rms energy bandwidth down to 0.5% and flux of about 108 photons/s. The system includes a set of detectors for the diagnostic and complete characterization of the gamma beam. To evaluate the spatial distribution of the beam a gamma beam profile imager is required. For this purpose, a detector based on a scintillator target coupled to a CCD camera was designed and a prototype was tested at INFN-Ferrara laboratories. A set of analytical calculations and Monte Carlo simulations were carried out to optimize the imager design and evaluate the performance expected with ELI-NP gamma beam. In this work the design of the imager is described in detail, as well as the simulation tools used and the results obtained. The simulation parameters were tuned and cross-checked with the experimental measurements carried out on the assembled prototype using the beam from an x-ray tube.

Development of neutron/gamma generators and a polymer semiconductor detector for homeland security applications

NASA Astrophysics Data System (ADS)

King, Michael Joseph

Instrumentation development is essential to the advancement and success of homeland security systems. Active interrogation techniques that scan luggage and cargo containers for shielded special nuclear materials or explosives hold great potential in halting further terrorist attacks. The development of more economical, compact and efficient source and radiation detection devices will facilitate scanning of all containers and luggage while maintaining high-throughput and low-false alarms Innovative ion sources were developed for two novel, specialized neutron generating devices and initial generator tests were performed. In addition, a low-energy acceleration gamma generator was developed and its performance characterized. Finally, an organic semiconductor was investigated for direct fast neutron detection. A main part of the thesis work was the development of ion sources, crucial components of the neutron/gamma generator development. The use of an externally-driven radio-frequency antenna allows the ion source to generate high beam currents with high, mono-atomic species fractions while maintaining low operating pressures, advantageous parameters for neutron generators. A dual "S" shaped induction antenna was developed to satisfy the high current and large extraction area requirements of the high-intensity neutron generator. The dual antenna arrangement generated a suitable current density of 28 mA/cm2 at practical RF power levels. The stringent requirements of the Pulsed Fast Neutron Transmission Spectroscopy neutron generator necessitated the development of a specialized ten window ion source of toroidal shape with a narrow neutron production target at its center. An innovative ten antenna arrangement with parallel capacitors was developed for driving the multi-antenna arrangement and uniform coupling of RF power to all ten antennas was achieved. To address the desire for low-impact, low-radiation dose active interrogation systems, research was performed on mono-energetic gamma generators that operate at low-acceleration energies and leverage neutron generator technologies. The dissertation focused on the experimental characterization of the generator performance and involved MCNPX simulations to evaluate and analyze the experimental results. The emission of the 11.7 MeV gamma-rays was observed to be slightly anisotropic and the gamma yield was measured to be 2.0*105 gamma/s-mA. The lanthanum hexaboride target suffered beam damage from a high power density beam; however, this may be overcome by sweeping the beam across a larger target area. The efficient detection of fast neutrons is vital to active interrogation techniques for the detection of both SNM and explosives. Novel organic semiconductors are air-stable, low-cost materials that demonstrate direct electronic particle detection. As part of the development of a pi-conjugated organic polymer for fast neutron detection, charge generation and collection properties were investigated. By devising a dual, thin-film detector test arrangement, charge collection was measured for high energy protons traversing the dual detector arrangement that allowed the creation of variable track lengths by tilting the detector. The results demonstrated that an increase in track length resulted in a decreased signal collection. This can be understood by assuming charge carrier transport along the track instead of along the field lines, which was made possible by the filling of traps. However, this charge collection mechanism may be insufficient to generate a useful signal. This dissertation has explored the viability of a new generation of radiation sources and detectors, where the newly developed ion source technologies and prototype generators will further enhance the capabilities of existing threat detection systems and promote the development of cutting-edge detection technologies.

VERITAS: status c.2005

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weekes, T. C.; Atkins, R. W.; Badran, H. M.

2006-07-11

VERITAS (Very Energetic Radiation Imaging Telescope Array System), is one of a new generation of TeV gamma-ray observatories. The current status of its construction is described here. The first two telescopes and cameras have been completed and meet the design specifications; the full array of four telescopes could be operational by the end of 2006.

Phantom feet on digital radionuclide images and other scary computer tales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freitas, J.E.; Dworkin, H.J.; Dees, S.M.

1989-09-01

Malfunction of a computer-assisted digital gamma camera is reported. Despite what appeared to be adequate acceptance testing, an error in the system gave rise to switching of images and identification text. A suggestion is made for using a hot marker, which would avoid the potential error of misinterpretation of patient images.

An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras.

PubMed

Bolotnikov, A E; Ackley, K; Camarda, G S; Cherches, C; Cui, Y; De Geronimo, G; Fried, J; Hodges, D; Hossain, A; Lee, W; Mahler, G; Maritato, M; Petryk, M; Roy, U; Salwen, C; Vernon, E; Yang, G; James, R B

2015-07-01

We developed a robust and low-cost array of virtual Frisch-grid CdZnTe detectors coupled to a front-end readout application-specific integrated circuit (ASIC) for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6 × 6 × 15 mm(3) detectors grouped into 3 × 3 sub-arrays of 2 × 2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics. The further enhancement of the arrays' performance and reduction of their cost are possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.

Absorbed radiation dose in adults from iodine-131 and iodine-123 orthoiodohippurate and technetium-99m DTPA renography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlsen, O.

1988-03-01

A mathematic model for evaluation of absorbed dose in radionuclide renography has been developed and programmed for automatic calculation in the computer. Input data to the model are readily available from the results of the renography and, hence, the method described is suitable for individual dose determinations in adults. Apart from the situation with very considerable outflow obstructions (/sup 131/I)OIH single probe renography involves a 15-20 times smaller dose to radiation sensitive organs than (/sup 123/I)OIH gamma camera renography. Further, the latter examination results in a 2-10 times smaller dose than (/sup 99m/Tc)DTPA gamma camera renography under normal outflow conditions.more » Absorbed renal dose is large, approximately 70 mGy, in the three renographies in the borderline case with total outflow obstructions. For comparison, i.v. pyelography, which is the x-ray examination often used instead of radionuclide renography, involves an absorbed dose to ovaries 10-1000 times larger than in radionuclide renography« less

An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

DOE PAGES

Bolotnikov, A. E.; Ackley, K.; Camarda, G. S.; ...

2015-07-28

We developed a robust and low-cost array of virtual Frisch-grid CdZnTe (CZT) detectors coupled to a front-end readout ASIC for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6x6x15 mm 3 detectors grouped into 3x3 sub-arrays of 2x2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readoutmore » electronics. The further enhancement of the arrays’ performance and reduction of their cost are made possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.« less

Metabolic cardiac imaging in severe coronary disease: assessment of viability with iodine-123-iodophenylpentadecanoic acid and multicrystal gamma camera, and correlation with biopsy.

PubMed

Murray, G; Schad, N; Ladd, W; Allie, D; vander Zwagg, R; Avet, P; Rockett, J

1992-07-01

Fifteen patients with coronary disease and resting left ventricular ejection fractions of less than or equal to 0.35 underwent resting metabolic cardiac imaging utilizing 1 mCi [123I]iodophenylpentadecanoic acid (IPPA) intravenously and a multicrystal gamma camera. Parametric images of regional rates of IPPA clearance and accumulation were generated. Forty-two vascular territories (22 infarcted) were evaluated by metabolic imaging as well as transmural myocardial biopsy. Despite resting akinesis or dyskinesis in 20/22 (91%) infarcted territories, 16/22 (73%) of these territories were metabolically viable. Transmural myocardial biopsies in all patients (43 sites, 42 vascular territories) during coronary bypass surgery confirmed IPPA results in 39/43 patients (91%). When compared to biopsy, scan sensitivity for viability was 33/36 (92%) with a specificity of 6/7 (86%). Eighty percent of bypassed, infarcted but IPPA viable segments demonstrated improved regional systolic wall motion postoperatively as assessed by exercise radionuclide angiography. We conclude resting IPPA imaging identifies viable myocardium, thereby providing a safe, cost-effective technique for myocardial viability assessment.

Observation of runaway electron beams by visible color camera in the Experimental Advanced Superconducting Tokamak

NASA Astrophysics Data System (ADS)

Shi, Yuejiang; Fu, Jia; Li, Jiahong; Yang, Yu; Wang, Fudi; Li, Yingying; Zhang, Wei; Wan, Baonian; Chen, Zhongyong

2010-03-01

The synchrotron radiation originated from the energetic runaway electrons has been measured by a visible complementary metal oxide semiconductor camera working in the wavelength ranges of 380-750 nm in the Experimental Advanced Superconducting Tokamak [H. Q. Liu et al., Plasma Phys. Contr. Fusion 49, 995 (2007)]. With a tangential viewing into the plasma in the direction of electron approach on the equatorial plane, the synchrotron radiation from the energetic runaway electrons was measured in full poloidal cross section. The synchrotron radiation diagnostics provides a direct pattern of the runaway beam inside the plasma. The energy and pitch angle of runaway electrons have been obtained according to the synchrotron radiation pattern. A stable shell shape of synchrotron radiation has been observed in a few runaway discharges.

Multimodal US-gamma imaging using collaborative robotics for cancer staging biopsies.

PubMed

Esposito, Marco; Busam, Benjamin; Hennersperger, Christoph; Rackerseder, Julia; Navab, Nassir; Frisch, Benjamin

2016-09-01

The staging of female breast cancer requires detailed information about the level of cancer spread through the lymphatic system. Common practice to obtain this information for patients with early-stage cancer is sentinel lymph node (SLN) biopsy, where LNs are radioactively identified for surgical removal and subsequent histological analysis. Punch needle biopsy is a less invasive approach but suffers from the lack of combined anatomical and nuclear information. We present and evaluate a system that introduces live collaborative robotic 2D gamma imaging in addition to live 2D ultrasound to identify SLNs in the surrounding anatomy. The system consists of a robotic arm equipped with both a gamma camera and a stereoscopic tracking system that monitors the position of an ultrasound probe operated by the physician. The arm cooperatively places the gamma camera parallel to the ultrasound imaging plane to provide live multimodal visualization and guidance. We validate the system by evaluating the target registration errors between fused nuclear and US image data in a phantom consisting of two spheres, one of which is filled with radioactivity. Medical experts perform punch biopsies on agar-gelatine phantoms with complex configurations of hot and cold lesions to provide a qualitative and quantitative evaluation of the system. The average point registration error for the overlay is [Formula: see text] mm. The time of the entire procedure was reduced by 36 %, with 80v of the biopsies being successful. The users' feedback was very positive, and the system was deemed to be very intuitive, with handling similar to classic US-guided needle biopsy. We present and evaluate the first medical collaborative robotic imaging system. Feedback from potential users for SLN punch needle biopsy is encouraging. Ongoing work investigates the clinical feasibility with more complex and realistic phantoms.

Imaging Polarimeter for a Sub-MeV Gamma-Ray All-sky Survey Using an Electron-tracking Compton Camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komura, S.; Takada, A.; Mizumura, Y.

2017-04-10

X-ray and gamma-ray polarimetry is a promising tool to study the geometry and the magnetic configuration of various celestial objects, such as binary black holes or gamma-ray bursts (GRBs). However, statistically significant polarizations have been detected in few of the brightest objects. Even though future polarimeters using X-ray telescopes are expected to observe weak persistent sources, there are no effective approaches to survey transient and serendipitous sources with a wide field of view (FoV). Here we present an electron-tracking Compton camera (ETCC) as a highly sensitive gamma-ray imaging polarimeter. The ETCC provides powerful background rejection and a high modulation factormore » over an FoV of up to 2 π sr thanks to its excellent imaging based on a well-defined point-spread function. Importantly, we demonstrated for the first time the stability of the modulation factor under realistic conditions of off-axis incidence and huge backgrounds using the SPring-8 polarized X-ray beam. The measured modulation factor of the ETCC was 0.65 ± 0.01 at 150 keV for an off-axis incidence with an oblique angle of 30° and was not degraded compared to the 0.58 ± 0.02 at 130 keV for on-axis incidence. These measured results are consistent with the simulation results. Consequently, we found that the satellite-ETCC proposed in Tanimori et al. would provide all-sky surveys of weak persistent sources of 13 mCrab with 10% polarization for a 10{sup 7} s exposure and over 20 GRBs down to a 6 × 10{sup −6} erg cm{sup −2} fluence and 10% polarization during a one-year observation.« less

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerologia Department of Nuclear Medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avila, O.; Torres-Ulloa, C. L.; Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, AP 70-542, 04510, DF

2010-12-07

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerologia, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with {sup 137}Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrologia, to known {sup 137}Cs gamma radiation air kerma. Radionuclides considered for this study are {sup 131}I, {sup 18}F, {sup 67}Ga, {sup 99m}Tc, {sup 111}In, {sup 201}Tl and {sup 137}Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placedmore » during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with {sup 131}I and {sup 137}Cs. High dose values were found at the waste storage room, outside corridor of {sup 137}Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the {sup 137}Cs brachytherapy corridor is equal to (18.51{+-}0.02)x10{sup -3} mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05{+-}0.03)x10{sup -3} mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).« less

Imaging Polarimeter for a Sub-MeV Gamma-Ray All-sky Survey Using an Electron-tracking Compton Camera

NASA Astrophysics Data System (ADS)

Komura, S.; Takada, A.; Mizumura, Y.; Miyamoto, S.; Takemura, T.; Kishimoto, T.; Kubo, H.; Kurosawa, S.; Matsuoka, Y.; Miuchi, K.; Mizumoto, T.; Nakamasu, Y.; Nakamura, K.; Oda, M.; Parker, J. D.; Sawano, T.; Sonoda, S.; Tanimori, T.; Tomono, D.; Yoshikawa, K.

2017-04-01

X-ray and gamma-ray polarimetry is a promising tool to study the geometry and the magnetic configuration of various celestial objects, such as binary black holes or gamma-ray bursts (GRBs). However, statistically significant polarizations have been detected in few of the brightest objects. Even though future polarimeters using X-ray telescopes are expected to observe weak persistent sources, there are no effective approaches to survey transient and serendipitous sources with a wide field of view (FoV). Here we present an electron-tracking Compton camera (ETCC) as a highly sensitive gamma-ray imaging polarimeter. The ETCC provides powerful background rejection and a high modulation factor over an FoV of up to 2π sr thanks to its excellent imaging based on a well-defined point-spread function. Importantly, we demonstrated for the first time the stability of the modulation factor under realistic conditions of off-axis incidence and huge backgrounds using the SPring-8 polarized X-ray beam. The measured modulation factor of the ETCC was 0.65 ± 0.01 at 150 keV for an off-axis incidence with an oblique angle of 30° and was not degraded compared to the 0.58 ± 0.02 at 130 keV for on-axis incidence. These measured results are consistent with the simulation results. Consequently, we found that the satellite-ETCC proposed in Tanimori et al. would provide all-sky surveys of weak persistent sources of 13 mCrab with 10% polarization for a 107 s exposure and over 20 GRBs down to a 6 × 10-6 erg cm-2 fluence and 10% polarization during a one-year observation.

Single photon emission tomography in neurological studies: Instrumentation and clinical applications

NASA Astrophysics Data System (ADS)

Nikkinen, Paivi Helena

One triple head and two single head gamma camera systems were used for single photon emission tomography (SPET) imaging of both patients and brain phantoms. Studies with an anatomical brain phantom were performed for evaluation of reconstruction and correction methods in brain perfusion SPET studies. The use of the triple head gamma camera system resulted in a significant increase in image contrast and resolution. This was mainly due to better imaging geometry and the use of a high resolution collimator. The conventional Chang attenuation correction was found suitable for the brain perfusion studies. In the brain perfusion studies region of interest (ROI) based semiquantitation methods were used. A ROI map based on anatomical areas was used in 70 elderly persons (age range 55-85 years) without neurological diseases and in patients suffering from encephalitis or having had a cardiac arrest. Semiquantitative reference values are presented. For the 14 patients with encephalitis the right-to-left side differences were calculated. Defect volume indexes were calculated for 64 patients with brain infarcts. For the 30 cardiac arrest patients the defect percentages and the anteroposterior ratios were used for semiquantitation. It is concluded that different semiquantitation methods are needed for the various patient groups. Age-related reference values will improve the interpretation of SPET data. For validation of the basal ganglia receptor studies measurements were performed using a cylindrical and an anatomical striatal phantom. In these measurements conventional and transmission imaging based non-uniform attenuation corrections were compared. A calibration curve was calculated for the determination of the specific receptor uptake ratio. In the phantom studies using the triple head camera the uptake ratio obtained from simultaneous transmission-emission protocol (STEP) acquisition and iterative reconstruction was closest to the true activity ratio. Conventional acquisition and uniform Chang attenuation correction gave 40% lower values. The effect of dual window scatter correction was also measured. In conventional reconstruction dual window scatter correction increased the uptake ratios when using a single head camera, but when using the triple head camera this correction did not have a significant effect on the ratios. Semiquantitative values for striatal 123I-labelled β-carbomethoxy-3β- (4-iodophenyl)tropane (123I-βCIT) dopamine transporter uptake in 20 adults (mean age 52 +/- 15 years) are presented. The mean basal ganglia to cerebellum ratio was 6.5 +/- 0.9 and the mean caudatus to putamen ratio was 1.2. The registration of brain SPET and magnetic resonance (MR) studies provides the necessary anatomical information for determination of the ROIs. A procedure for registration and simultaneous display of brain SPET and MR images based on six external skin markers is presented. The usefulness of this method was demonstrated in selected patients. The registration accuracy was determined for single and triple head gamma camera systems using brain phantom and simulation studies. The registration residual for three internal test markers was calculated using 4 to 13 external markers in the registration. For 6 external markers, as used in the registration in the patient studies, the mean RMS residuals of the test markers for the single head camera and the triple head camera were 3.5 mm and 3.2 mm, respectively. According to the simulation studies the largest inaccuracy is due mainly to the spatial resolution of SPET. The use of six markers, as in the patient studies, is adequate for accurate registration.

X-ray emission from high temperature plasmas

NASA Technical Reports Server (NTRS)

Harries, W. L.

1974-01-01

X-rays from a 25-hJ plasma focus apparatus were observed with pinhole cameras. The cameras consist of 0.4 mm diameter pinholes in 2 cm thick lead housing enclosing an X-ray intensifying screen at the image plane. Pictures recorded through thin aluminum foils or plastic sheets for X-ray energies sub gamma smaller than 15 keV show distributed X-ray emissions from the focussed plasma and from the anode surface. However, when thick absorbers are used, radial filamentary structure in the X-ray emission from the anode surface is revealed. Occasionally larger structures are observed in addition to the filaments. Possible mechanisms for the filamentary structure are discussed.

Using a smart phone application to measure high-energy radiation from thunderstorms

NASA Astrophysics Data System (ADS)

Bowers, G. S.; Smith, D. M.; Rexroad, W. Z.; Kelley, N. A.; Martinez-Mckinney, F.; Rubenstein, E. P.; Drukier, G.; Benes, G. N.

2013-12-01

Commercial airline flights and developing cell phone technologies present a burgeoning opportunity for the public to help investigate radiation from thunderstorms, including terrestrial gamma-ray flashes (TGFs), longer-lived gamma-ray glows, x-rays from lightning stepped leaders, and possible high-energy radiation, never yet observed, from blue jets, gigantic jets, and blue starters. GammaPix is a smartphone application from Image Insight, Inc. that uses the camera's CCD or CMOS sensor to identify and qualitatively assess threats related to gamma radioactivity, e.g., those caused by accidental exposure to radioactive material, high-altitude air travel, or acts of terrorism. A science-oriented version of the app is under development that will be publicized for use aboard commercial airline flights and on the ground in regions (like Japan in the wintertime) where thunderstorm charge centers come close to the ground. The primary goal of the project is to learn whether TGFs close to passenger aircraft and population centers on the ground occur often enough to create concern about radiation risk.

Pixel detectors for x-ray imaging spectroscopy in space

NASA Astrophysics Data System (ADS)

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.

Simultaneous fluoroscopic and nuclear imaging: impact of collimator choice on nuclear image quality.

PubMed

van der Velden, Sandra; Beijst, Casper; Viergever, Max A; de Jong, Hugo W A M

2017-01-01

X-ray-guided oncological interventions could benefit from the availability of simultaneously acquired nuclear images during the procedure. To this end, a real-time, hybrid fluoroscopic and nuclear imaging device, consisting of an X-ray c-arm combined with gamma imaging capability, is currently being developed (Beijst C, Elschot M, Viergever MA, de Jong HW. Radiol. 2015;278:232-238). The setup comprises four gamma cameras placed adjacent to the X-ray tube. The four camera views are used to reconstruct an intermediate three-dimensional image, which is subsequently converted to a virtual nuclear projection image that overlaps with the X-ray image. The purpose of the present simulation study is to evaluate the impact of gamma camera collimator choice (parallel hole versus pinhole) on the quality of the virtual nuclear image. Simulation studies were performed with a digital image quality phantom including realistic noise and resolution effects, with a dynamic frame acquisition time of 1 s and a total activity of 150 MBq. Projections were simulated for 3, 5, and 7 mm pinholes and for three parallel hole collimators (low-energy all-purpose (LEAP), low-energy high-resolution (LEHR) and low-energy ultra-high-resolution (LEUHR)). Intermediate reconstruction was performed with maximum likelihood expectation-maximization (MLEM) with point spread function (PSF) modeling. In the virtual projection derived therefrom, contrast, noise level, and detectability were determined and compared with the ideal projection, that is, as if a gamma camera were located at the position of the X-ray detector. Furthermore, image deformations and spatial resolution were quantified. Additionally, simultaneous fluoroscopic and nuclear images of a sphere phantom were acquired with a physical prototype system and compared with the simulations. For small hot spots, contrast is comparable for all simulated collimators. Noise levels are, however, 3 to 8 times higher in pinhole geometries than in parallel hole geometries. This results in higher contrast-to-noise ratios for parallel hole geometries. Smaller spheres can thus be detected with parallel hole collimators than with pinhole collimators (17 mm vs 28 mm). Pinhole geometries show larger image deformations than parallel hole geometries. Spatial resolution varied between 1.25 cm for the 3 mm pinhole and 4 cm for the LEAP collimator. The simulation method was successfully validated by the experiments with the physical prototype. A real-time hybrid fluoroscopic and nuclear imaging device is currently being developed. Image quality of nuclear images obtained with different collimators was compared in terms of contrast, noise, and detectability. Parallel hole collimators showed lower noise and better detectability than pinhole collimators. © 2016 American Association of Physicists in Medicine.

The effects of Doppler broadening and detector resolution on the performance of three-stage Compton cameras

PubMed Central

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

2013-01-01

Purpose: The authors investigated how the characteristics of the detectors used in a three-stage Compton camera (CC) affect the CC's ability to accurately measure the emission distribution and energy spectrum of prompt gammas (PG) emitted by nuclear de-excitations during proton therapy. The detector characteristics they studied included the material (high-purity germanium [HPGe] and cadmium zinc telluride [CZT]), Doppler broadening (DB), and resolution (lateral, depth, and energy). Methods: The authors simulated three-stage HPGe and CZT CCs of various configurations, detecting gammas from point sources with energies ranging from 0.511 to 7.12 MeV. They also simulated a proton pencil beam irradiating a tissue target to study how the detector characteristics affect the PG data measured by CCs in a clinical proton therapy setting. They used three figures of merit: the distance of closest approach (DCA) and the point of closest approach (PCA) between the measured and actual position of the PG emission origin, and the calculated energy resolution. Results: For CCs with HPGe detectors, DB caused the DCA to be greater than 3 mm for 14% of the 6.13 MeV gammas and 20% of the 0.511 MeV gammas. For CCs with CZT detectors, DB caused the DCA to be greater than 3 mm for 18% of the 6.13 MeV gammas and 25% of the 0.511 MeV gammas. The full width at half maximum (FWHM) of the PCA in the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\hat z\\end{equation*} \\end{document}z^ direction for HPGe and CZT detectors ranged from 1.3 to 0.4 mm for gammas with incident energy ranging from 0.511 to 7.12 MeV. For CCs composed of HPGe detectors, the resolution of incident gamma energy calculated by the CC ranged from 6% to 1% for gammas with true incident energies from 0.511 to 7.12 MeV. For CCs composed of CZT detectors, the resolution of gamma energy calculated by the CC ranged from 10% to 1% for gammas with true incident energies from 0.511 to 7.12 MeV. For HPGe and CZT CCs in which all detector effect were included, the DCA was less than 3 mm for 75% and 68% of the detected gammas, respectively, and restricting gammas to those having energy greater than 2.0 MeV increased these percentages to 83% and 77% for HPGe and CZT, respectively. Distributions of the true gamma origins and the PCA after detector characteristics had been included showed good agreement on beam range and some loss of resolution for the lateral profile of the PG emission. Characteristic energy lines were evident in the calculated gamma energy spectrum. Conclusions: The authors found the following: (1) DB is the dominant source of spatial and energy resolution loss in the CCs at all energy levels; (2) the largest difference in the spatial resolution of HPGe and CZT CCs is that the spatial resolution distributions of CZT have broader tails. The differences in the FWHM of these distributions are small; (3) the energy resolution of both HPGe and CZT three-stage CCs is adequate for PG spectroscopy; and (4) restricting the gammas to those having energy greater than 2.0 MeV can improve the achievable image resolution. PMID:23298111

Low Statistics Reconstruction of the Compton Camera Point Spread Function in 3D Prompt-γ Imaging of Ion Beam Therapy

NASA Astrophysics Data System (ADS)

Lojacono, Xavier; Richard, Marie-Hélène; Ley, Jean-Luc; Testa, Etienne; Ray, Cédric; Freud, Nicolas; Létang, Jean Michel; Dauvergne, Denis; Maxim, Voichiţa; Prost, Rémy

2013-10-01

The Compton camera is a relevant imaging device for the detection of prompt photons produced by nuclear fragmentation in hadrontherapy. It may allow an improvement in detection efficiency compared to a standard gamma-camera but requires more sophisticated image reconstruction techniques. In this work, we simulate low statistics acquisitions from a point source having a broad energy spectrum compatible with hadrontherapy. We then reconstruct the image of the source with a recently developed filtered backprojection algorithm, a line-cone approach and an iterative List Mode Maximum Likelihood Expectation Maximization algorithm. Simulated data come from a Compton camera prototype designed for hadrontherapy online monitoring. Results indicate that the achievable resolution in directions parallel to the detector, that may include the beam direction, is compatible with the quality control requirements. With the prototype under study, the reconstructed image is elongated in the direction orthogonal to the detector. However this direction is of less interest in hadrontherapy where the first requirement is to determine the penetration depth of the beam in the patient. Additionally, the resolution may be recovered using a second camera.

Elemental abundances of the B and A stars. 2: Gamma Geminorum, HD 60825, 7 Sextantis, HR 4817, and HR 5780

NASA Technical Reports Server (NTRS)

Adelman, Saul J.; Philip, A. G. Davis

1994-01-01

We extend fine analyses of the B and A stars, gamma Geminorum, 7 Sextantis, HR 4817, and HR 5780 using additional spectroscopic data from the Kitt Peak National Observatory (KPNO) coude feed telescope with a TI CCD, camera 5, and grating A, and ATLAS9 model atmospheres. In addition we study HD 60825, which had colors similar to the FHB A stars, but was found to be a Population I star. HD 60825, as is gamma Gem, is a sharp-lined early-A star with nearly solar derived abundances. HR 5780 and 7 Sex are also examples of stars which for the most part have solar abundances. The newly derived abundances for HR 4817 reveal important differences with respect to 53 Tau, a somewhat similar HgMn star.

Total-dose radiation effects data for semiconductor devices, volume 2

NASA Technical Reports Server (NTRS)

Price, W. E.; Martin, K. E.; Nichols, D. K.; Gauthier, M. K.; Brown, S. F.

1981-01-01

Total ionizing dose radiation test data on integrated circuits are analyzed. Tests were performed with the electron accelerator (Dynamitron) that provides a steady state 2.5 MeV electron beam. Some radiation exposures were made with a Cobalt-60 gamma ray source. The results obtained with the Cobalt-60 source are considered an approximate measure of the radiation damage that would be incurred by an equivalent dose of electrons.

Neutron detection with LiInSe2

NASA Astrophysics Data System (ADS)

Bell, Zane W.; Burger, A.; Matei, Liviu; Groza, Michael; Stowe, Ashley; Tower, Joshua; Kargar, Alireza; Hong, Huicong

2015-08-01

The detection of thermal neutrons has traditionally been accomplished with 3He-tubes, but with the recent shortage of 3He, much research has gone into finding suitable replacements. Both relatively inefficient 10B- and 6LiF-coated silicon diodes and HgI2 have been known for many years, and engineered structures in Si that have been filled with 10B and 6LiF have shown promise. These devices are intended to realize an optimal juxtaposition of neutron-sensitive material and semiconductor and thereby simulate a semiconductor containing B or Li. Such material has been realized for the first time in the form of 6LiInSe2 in which collectable charge from the 6Li(n,t) reaction indicates a neutron event. In this paper we report neutron and gamma responses of 6LiInSe2, we show pulse height spectra from pure gamma sources and from a thermal neutron source, and we derive the μτ product from the position of spectral features as a function of bias voltage. In addition, we demonstrate the observation of the beta decay of 116mIn in samples exposed to thermal neutrons. This feature of the response serves as an additional confirmation of exposure to neutrons.

Monte Carlo simulation to calculate the rate of 137Cs gamma rays dispersion in gallium arsenide compound

NASA Astrophysics Data System (ADS)

Haider, F. A.; Chee, F. P.; Abu Hassan, H.; Saafie, S.

2017-01-01

Radiation effects on Gallium Arsenide (GaAs) have been tested by exposing samples to Cesium-137 (137Cs) gamma rays. Gallium Arsenide is a basic photonic material for most of the space technology communication, and, therefore, lends itself for applications where this is of concern. Monte Carlo simulations of interaction between direct ionizing radiation and GaAs structure have been performed in TRIM software, being part of SRIM 2011 programming package. An adverse results shows that energy dose does not govern the displacement of atoms and is dependent on the changes of incident angles and thickness of the GaAs target element. At certain thickness of GaAs and incident angle of 137Cs ion, the displacement damage is at its highest value. From the simulation result, it is found that if the thickness of the GaAs semiconductor material is small compared to the projected range at that particular incident energy, the energy loss in the target GaAs will be small. Hence, when the depth of semiconductor material is reduced, the range of damage in the target also decreased. However, the other factors such as quantum size effect, the energy gap between the conduction and valence band must also be taken into consideration when the dimension of the device is diminished.

Growth of Bulk Wide Bandgap Semiconductor Crystals and Their Potential Applications

NASA Technical Reports Server (NTRS)

Chen, Kuo-Tong; Shi, Detang; Morgan, S. H.; Collins, W. Eugene; Burger, Arnold

1997-01-01

Developments in bulk crystal growth research for electro-optical devices in the Center for Photonic Materials and Devices since its establishment have been reviewed. Purification processes and single crystal growth systems employing physical vapor transport and Bridgman methods were assembled and used to produce high purity and superior quality wide bandgap materials such as heavy metal halides and II-VI compound semiconductors. Comprehensive material characterization techniques have been employed to reveal the optical, electrical and thermodynamic properties of crystals, and the results were used to establish improved material processing procedures. Postgrowth treatments such as passivation, oxidation, chemical etching and metal contacting during the X-ray and gamma-ray device fabrication process have also been investigated and low noise threshold with improved energy resolution has been achieved.

Total-dose radiation effects data for semiconductor devices. 1985 supplement. Volume 2, part A

NASA Technical Reports Server (NTRS)

Martin, K. E.; Gauthier, M. K.; Coss, J. R.; Dantas, A. R. V.; Price, W. E.

1986-01-01

Steady-state, total-dose radiation test data, are provided in graphic format for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. This volume provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done using the JPL or Boeing electron accelerator (Dynamitron) which provides a steady-state 2.5 MeV electron beam. However, some radiation exposures were made with a Cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose.

Fracture-resistant lanthanide scintillators

DOEpatents

Doty, F Patrick [Livermore, CA

2011-01-04

Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (<3% FWHM energy resolutions at 662 keV). However brittle fracture of these materials upon cooling hinders the growth of large volume crystals. Efforts to improve the strength through non-lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

Evaluation of the applicability of the SeHCAT test in the investigation of patients with diarrhoea.

PubMed

Orholm, M; Pedersen, J O; Arnfred, T; Rødbro, P; Thaysen, E H

1988-01-01

For the assessment of ileal bile acid conservation the retention of orally administered 75Se-23-selena-25-homotaurocholic acid (SeHCAT), a gamma-ray-emitting radioisotope-labelled synthetic bile acid, was measured by an uncollimated abdominal gamma camera in 89 patients with various gastrointestinal disorders and in 20 persons without gastrointestinal complaints. A significant differences in retention was observed between patients with and without previously detected ileal disease. However, it was not possible by use of the test to differentiate between the various types of diarrhoea. Hence the test is not recommended in the routine investigation of patients with diarrhoea.

Fabricating High-Resolution X-Ray Collimators

NASA Technical Reports Server (NTRS)

Appleby, Michael; Atkinson, James E.; Fraser, Iain; Klinger, Jill

2008-01-01

A process and method for fabricating multi-grid, high-resolution rotating modulation collimators for arcsecond and sub-arcsecond x-ray and gamma-ray imaging involves photochemical machining and precision stack lamination. The special fixturing and etching techniques that have been developed are used for the fabrication of multiple high-resolution grids on a single array substrate. This technology has application in solar and astrophysics and in a number of medical imaging applications including mammography, computed tomography (CT), single photon emission computed tomography (SPECT), and gamma cameras used in nuclear medicine. This collimator improvement can also be used in non-destructive testing, hydrodynamic weapons testing, and microbeam radiation therapy.

Collimator-free photon tomography

DOEpatents

Dilmanian, F. Avraham; Barbour, Randall L.

1998-10-06

A method of uncollimated single photon emission computed tomography includes administering a radioisotope to a patient for producing gamma ray photons from a source inside the patient. Emissivity of the photons is measured externally of the patient with an uncollimated gamma camera at a plurality of measurement positions surrounding the patient for obtaining corresponding energy spectrums thereat. Photon emissivity at the plurality of measurement positions is predicted using an initial prediction of an image of the source. The predicted and measured photon emissivities are compared to obtain differences therebetween. Prediction and comparison is iterated by updating the image prediction until the differences are below a threshold for obtaining a final prediction of the source image.

A comparison of imaging methods for use in an array biosensor

NASA Technical Reports Server (NTRS)

Golden, Joel P.; Ligler, Frances S.

2002-01-01

An array biosensor has been developed which uses an actively-cooled, charge-coupled device (CCD) imager. In an effort to save money and space, a complementary metal-oxide semiconductor (CMOS) camera and photodiode were tested as replacements for the cooled CCD imager. Different concentrations of CY5 fluorescent dye in glycerol were imaged using the three different detection systems with the same imaging optics. Signal discrimination above noise was compared for each of the three systems.

Photon statistics in scintillation crystals

NASA Astrophysics Data System (ADS)

Bora, Vaibhav Joga Singh

Scintillation based gamma-ray detectors are widely used in medical imaging, high-energy physics, astronomy and national security. Scintillation gamma-ray detectors are eld-tested, relatively inexpensive, and have good detection eciency. Semi-conductor detectors are gaining popularity because of their superior capability to resolve gamma-ray energies. However, they are relatively hard to manufacture and therefore, at this time, not available in as large formats and much more expensive than scintillation gamma-ray detectors. Scintillation gamma-ray detectors consist of: a scintillator, a material that emits optical (scintillation) photons when it interacts with ionization radiation, and an optical detector that detects the emitted scintillation photons and converts them into an electrical signal. Compared to semiconductor gamma-ray detectors, scintillation gamma-ray detectors have relatively poor capability to resolve gamma-ray energies. This is in large part attributed to the "statistical limit" on the number of scintillation photons. The origin of this statistical limit is the assumption that scintillation photons are either Poisson distributed or super-Poisson distributed. This statistical limit is often dened by the Fano factor. The Fano factor of an integer-valued random process is dened as the ratio of its variance to its mean. Therefore, a Poisson process has a Fano factor of one. The classical theory of light limits the Fano factor of the number of photons to a value greater than or equal to one (Poisson case). However, the quantum theory of light allows for Fano factors to be less than one. We used two methods to look at the correlations between two detectors looking at same scintillation pulse to estimate the Fano factor of the scintillation photons. The relationship between the Fano factor and the correlation between the integral of the two signals detected was analytically derived, and the Fano factor was estimated using the measurements for SrI2:Eu, YAP:Ce and CsI:Na. We also found an empirical relationship between the Fano factor and the covariance as a function of time between two detectors looking at the same scintillation pulse. This empirical model was used to estimate the Fano factor of LaBr3:Ce and YAP:Ce using the experimentally measured timing-covariance. The estimates of the Fano factor from the time-covariance results were consistent with the estimates of the correlation between the integral signals. We found scintillation light from some scintillators to be sub-Poisson. For the same mean number of total scintillation photons, sub-Poisson light has lower noise. We then conducted a simulation study to investigate whether this low-noise sub-Poisson light can be used to improve spatial resolution. We calculated the Cramer-Rao bound for dierent detector geometries, position of interactions and Fano factors. The Cramer-Rao calculations were veried by generating simulated data and estimating the variance of the maximum likelihood estimator. We found that the Fano factor has no impact on the spatial resolution in gamma-ray imaging systems.

SU-D-BRC-07: System Design for a 3D Volumetric Scintillation Detector Using SCMOS Cameras

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darne, C; Robertson, D; Alsanea, F

2016-06-15

Purpose: The purpose of this project is to build a volumetric scintillation detector for quantitative imaging of 3D dose distributions of proton beams accurately in near real-time. Methods: The liquid scintillator (LS) detector consists of a transparent acrylic tank (20×20×20 cm{sup 3}) filled with a liquid scintillator that when irradiated with protons generates scintillation light. To track rapid spatial and dose variations in spot scanning proton beams we used three scientific-complementary metal-oxide semiconductor (sCMOS) imagers (2560×2160 pixels). The cameras collect optical signal from three orthogonal projections. To reduce system footprint two mirrors oriented at 45° to the tank surfaces redirectmore » scintillation light to cameras for capturing top and right views. Selection of fixed focal length objective lenses for these cameras was based on their ability to provide large depth of field (DoF) and required field of view (FoV). Multiple cross-hairs imprinted on the tank surfaces allow for image corrections arising from camera perspective and refraction. Results: We determined that by setting sCMOS to 16-bit dynamic range, truncating its FoV (1100×1100 pixels) to image the entire volume of the LS detector, and using 5.6 msec integration time imaging rate can be ramped up to 88 frames per second (fps). 20 mm focal length lens provides a 20 cm imaging DoF and 0.24 mm/pixel resolution. Master-slave camera configuration enable the slaves to initiate image acquisition instantly (within 2 µsec) after receiving a trigger signal. A computer with 128 GB RAM was used for spooling images from the cameras and can sustain a maximum recording time of 2 min per camera at 75 fps. Conclusion: The three sCMOS cameras are capable of high speed imaging. They can therefore be used for quick, high-resolution, and precise mapping of dose distributions from scanned spot proton beams in three dimensions.« less

Development of a Compton camera for prompt-gamma medical imaging

NASA Astrophysics Data System (ADS)

Aldawood, S.; Thirolf, P. G.; Miani, A.; Böhmer, M.; Dedes, G.; Gernhäuser, R.; Lang, C.; Liprandi, S.; Maier, L.; Marinšek, T.; Mayerhofer, M.; Schaart, D. R.; Lozano, I. Valencia; Parodi, K.

2017-11-01

A Compton camera-based detector system for photon detection from nuclear reactions induced by proton (or heavier ion) beams is under development at LMU Munich, targeting the online range verification of the particle beam in hadron therapy via prompt-gamma imaging. The detector is designed to be capable to reconstruct the photon source origin not only from the Compton scattering kinematics of the primary photon, but also to allow for tracking of the secondary Compton-scattered electrons, thus enabling a γ-source reconstruction also from incompletely absorbed photon events. The Compton camera consists of a monolithic LaBr3:Ce scintillation crystal, read out by a multi-anode PMT acting as absorber, preceded by a stacked array of 6 double-sided silicon strip detectors as scatterers. The detector components have been characterized both under offline and online conditions. The LaBr3:Ce crystal exhibits an excellent time and energy resolution. Using intense collimated 137Cs and 60Co sources, the monolithic scintillator was scanned on a fine 2D grid to generate a reference library of light amplitude distributions that allows for reconstructing the photon interaction position using a k-Nearest Neighbour (k-NN) algorithm. Systematic studies were performed to investigate the performance of the reconstruction algorithm, revealing an improvement of the spatial resolution with increasing photon energy to an optimum value of 3.7(1)mm at 1.33 MeV, achieved with the Categorical Average Pattern (CAP) modification of the k-NN algorithm.

Precision of FLEET Velocimetry Using High-speed CMOS Camera Systems

NASA Technical Reports Server (NTRS)

Peters, Christopher J.; Danehy, Paul M.; Bathel, Brett F.; Jiang, Naibo; Calvert, Nathan D.; Miles, Richard B.

2015-01-01

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 micro sec, precisions of 0.5 m/s in air and 0.2 m/s in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision High Speed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

Measurement of the Shape of the Optical-IR Spectrum of Prompt Emission from Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Grossan, Bruce; Kistaubayev, M.; Smoot, G.; Scherr, L.

2017-06-01

While the afterglow phase of gamma-ray bursts (GRBs) has been extensively measured, detections of prompt emission (i.e. during bright X-gamma emission) are more limited. Some prompt optical measurements are regularly made, but these are typically in a single wide band, with limited time resolution, and no measurement of spectral shape. Some models predict a synchrotron self-absorption spectral break somewhere in the IR-optical region. Measurement of the absorption frequency would give extensive information on each burst, including the electron Lorentz factor, the radius of emission, and more (Shen & Zhang 2008). Thus far the best prompt observations have been explained invoking a variety of models, but often with a non-unique interpretation. To understand this apparently heterogeneous behavior, and to reduce the number of possible models, it is critical to add data on the optical - IR spectral shape.Long GRB prompt X-gamma emission typically lasts ~40-80 s. The Swift BAT instrument rapidly measures GRB positions to within a few arc minutes and communicates them via the internet within a few seconds. We have measured the time for a fast-moving D=700 mm telescope to point and settle to be less than 9 s anywhere on the observable sky. Therefore, the majority of prompt optical-IR emission can be measured responding to BAT positions with this telescope. In this presentation, we describe our observing and science programs, and give our design for the Burst Simultaneous Three-channel Instrument (BSTI), which uses dichroics to send eparate bands to 3 cameras. Two EMCCD cameras, give high-time resolution in B and V; a third camera with a HgCdTe sensor covers H band, allowing us to study extinguished bursts. For a total exposure time of 10 s, we find a 5 sigma sensitivity of 21.3 and 20.3 mag in B and R for 1" seeing and Kitt Peak sky brightness, much fainter than typical previous prompt detections. We estimate 5 sigma H-band sensitivity for an IR optimized telescope to be ~16.9 mag in 20 s. With three channels broadly separated in wavelength, two separate slopes would be measured, or if present between our bands, the absorption frequency would be determined, a brand-new window into GRB physics.

Flexible nuclear medicine camera and method of using

DOEpatents

Dilmanian, F. Avraham; Packer, Samuel; Slatkin, Daniel N.

1996-12-10

A nuclear medicine camera 10 and method of use photographically record radioactive decay particles emitted from a source, for example a small, previously undetectable breast cancer, inside a patient. The camera 10 includes a flexible frame 20 containing a window 22, a photographic film 24, and a scintillation screen 26, with or without a gamma-ray collimator 34. The frame 20 flexes for following the contour of the examination site on the patient, with the window 22 being disposed in substantially abutting contact with the skin of the patient for reducing the distance between the film 24 and the radiation source inside the patient. The frame 20 is removably affixed to the patient at the examination site for allowing the patient mobility to wear the frame 20 for a predetermined exposure time period. The exposure time may be several days for obtaining early qualitative detection of small malignant neoplasms.

Long-term effects of prenatal exposure to low levels of gamma rays on open-field activity in male mice.

PubMed

Minamisawa, T; Hirokaga, K

1995-11-01

The open-field activity of first-generation (F1) hybrid male C57BL/6 x C3H mice irradiated with gamma rays on day 14 of gestation was studied at the following ages: 6-7 months (young), 12-13 months (adult) and 19-20 months (old). Doses were 0.5 Gy or 1.0 Gy. Open-field activity was recorded with a camera. The camera output signal was recorded every second through an A/D converter to a personal computer. The field was divided into 25 8-cm2 units. All recordings were continuous for 60 min. The walking speed of the 1.0-Gy group recorded at 19-20 months was higher than that for the comparably aged control group. The time which the irradiated group, recorded at 19-20 months, spent in the corner fields was high in comparison with the control group at the same age. Conversely, the time spent by the irradiated group in the middle fields when recorded at 19-20 months was shorter than in the comparably aged control group. No effect of radiation was shown for any of the behaviors observed and recorded at 6-7 and 12-13 months. The results demonstrate that such exposure to gamma rays on day 14 of gestation results in behavioral changes which occur at 19-20 months but not at 6-7 or 12-13 months.

A new variable parallel holes collimator for scintigraphic device with validation method based on Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Trinci, G.; Massari, R.; Scandellari, M.; Boccalini, S.; Costantini, S.; Di Sero, R.; Basso, A.; Sala, R.; Scopinaro, F.; Soluri, A.

2010-09-01

The aim of this work is to show a new scintigraphic device able to change automatically the length of its collimator in order to adapt the spatial resolution value to gamma source distance. This patented technique replaces the need for collimator change that standard gamma cameras still feature. Monte Carlo simulations represent the best tool in searching new technological solutions for such an innovative collimation structure. They also provide a valid analysis on response of gamma cameras performances as well as on advantages and limits of this new solution. Specifically, Monte Carlo simulations are realized with GEANT4 (GEometry ANd Tracking) framework and the specific simulation object is a collimation method based on separate blocks that can be brought closer and farther, in order to reach and maintain specific spatial resolution values for all source-detector distances. To verify the accuracy and the faithfulness of these simulations, we have realized experimental measurements with identical setup and conditions. This confirms the power of the simulation as an extremely useful tool, especially where new technological solutions need to be studied, tested and analyzed before their practical realization. The final aim of this new collimation system is the improvement of the SPECT techniques, with the real control of the spatial resolution value during tomographic acquisitions. This principle did allow us to simulate a tomographic acquisition of two capillaries of radioactive solution, in order to verify the possibility to clearly distinguish them.

Caliste 64, a new CdTe micro-camera for hard X-ray spectro-imaging

NASA Astrophysics Data System (ADS)

Meuris, A.; Limousin, O.; Lugiez, F.; Gevin, O.; Blondel, C.; Pinsard, F.; Vassal, M. C.; Soufflet, F.; Le Mer, I.

2009-10-01

In the frame of the Simbol-X mission of hard X-ray astrophysics, a prototype of micro-camera with 64 pixels called Caliste 64 has been designed and several samples have been tested. The device integrates ultra-low-noise IDeF-X V1.1 ASICs from CEA and a 1 cm 2 Al Schottky CdTe detector from Acrorad because of its high uniformity and spectroscopic performance. The process of hybridization, mastered by the 3D Plus company, respects space applications standards. The camera is a spectro-imager with time-tagging capability. Each photon interacting in the semiconductor is tagged with a time, a position and an energy. Time resolution is better than 100 ns rms for energy deposits greater than 20 keV, taking into account electronic noise and technological dispersal of the front-end electronics. The spectrum summed across the 64 pixels results in an energy resolution of 664 eV fwhm at 13.94 keV and 842 eV fwhm at 59.54 keV, when the detector is cooled down to -10 °C and biased at -500 V.

Hyperspectral Image-Based Night-Time Vehicle Light Detection Using Spectral Normalization and Distance Mapper for Intelligent Headlight Control.

PubMed

Kim, Heekang; Kwon, Soon; Kim, Sungho

2016-07-08

This paper proposes a vehicle light detection method using a hyperspectral camera instead of a Charge-Coupled Device (CCD) or Complementary metal-Oxide-Semiconductor (CMOS) camera for adaptive car headlamp control. To apply Intelligent Headlight Control (IHC), the vehicle headlights need to be detected. Headlights are comprised from a variety of lighting sources, such as Light Emitting Diodes (LEDs), High-intensity discharge (HID), and halogen lamps. In addition, rear lamps are made of LED and halogen lamp. This paper refers to the recent research in IHC. Some problems exist in the detection of headlights, such as erroneous detection of street lights or sign lights and the reflection plate of ego-car from CCD or CMOS images. To solve these problems, this study uses hyperspectral images because they have hundreds of bands and provide more information than a CCD or CMOS camera. Recent methods to detect headlights used the Spectral Angle Mapper (SAM), Spectral Correlation Mapper (SCM), and Euclidean Distance Mapper (EDM). The experimental results highlight the feasibility of the proposed method in three types of lights (LED, HID, and halogen).

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

NASA Astrophysics Data System (ADS)

Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

2016-11-01

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited).

PubMed

Cooper, C M; Pace, D C; Paz-Soldan, C; Commaux, N; Eidietis, N W; Hollmann, E M; Shiraki, D

2016-11-01

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

DOE PAGES

Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; ...

2016-08-30

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20,000 pulses permore » second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Furthermore, magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.« less

Design optimisation of a TOF-based collimated camera prototype for online hadrontherapy monitoring

NASA Astrophysics Data System (ADS)

Pinto, M.; Dauvergne, D.; Freud, N.; Krimmer, J.; Letang, J. M.; Ray, C.; Roellinghoff, F.; Testa, E.

2014-12-01

Hadrontherapy is an innovative radiation therapy modality for which one of the main key advantages is the target conformality allowed by the physical properties of ion species. However, in order to maximise the exploitation of its potentialities, online monitoring is required in order to assert the treatment quality, namely monitoring devices relying on the detection of secondary radiations. Herein is presented a method based on Monte Carlo simulations to optimise a multi-slit collimated camera employing time-of-flight selection of prompt-gamma rays to be used in a clinical scenario. In addition, an analytical tool is developed based on the Monte Carlo data to predict the expected precision for a given geometrical configuration. Such a method follows the clinical workflow requirements to simultaneously have a solution that is relatively accurate and fast. Two different camera designs are proposed, considering different endpoints based on the trade-off between camera detection efficiency and spatial resolution to be used in a proton therapy treatment with active dose delivery and assuming a homogeneous target.

Upgraded cameras for the HESS imaging atmospheric Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Giavitto, Gianluca; Ashton, Terry; Balzer, Arnim; Berge, David; Brun, Francois; Chaminade, Thomas; Delagnes, Eric; Fontaine, Gérard; Füßling, Matthias; Giebels, Berrie; Glicenstein, Jean-François; Gräber, Tobias; Hinton, James; Jahnke, Albert; Klepser, Stefan; Kossatz, Marko; Kretzschmann, Axel; Lefranc, Valentin; Leich, Holger; Lüdecke, Hartmut; Lypova, Iryna; Manigot, Pascal; Marandon, Vincent; Moulin, Emmanuel; de Naurois, Mathieu; Nayman, Patrick; Penno, Marek; Ross, Duncan; Salek, David; Schade, Markus; Schwab, Thomas; Simoni, Rachel; Stegmann, Christian; Steppa, Constantin; Thornhill, Julian; Toussnel, François

2016-08-01

The High Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov telescopes, sensitive to cosmic gamma rays of energies between 30 GeV and several tens of TeV. Four of them started operations in 2003 and their photomultiplier tube (PMT) cameras are currently undergoing a major upgrade, with the goals of improving the overall performance of the array and reducing the failure rate of the ageing systems. With the exception of the 960 PMTs, all components inside the camera have been replaced: these include the readout and trigger electronics, the power, ventilation and pneumatic systems and the control and data acquisition software. New designs and technical solutions have been introduced: the readout makes use of the NECTAr analog memory chip, which samples and stores the PMT signals and was developed for the Cherenkov Telescope Array (CTA). The control of all hardware subsystems is carried out by an FPGA coupled to an embedded ARM computer, a modular design which has proven to be very fast and reliable. The new camera software is based on modern C++ libraries such as Apache Thrift, ØMQ and Protocol buffers, offering very good performance, robustness, flexibility and ease of development. The first camera was upgraded in 2015, the other three cameras are foreseen to follow in fall 2016. We describe the design, the performance, the results of the tests and the lessons learned from the first upgraded H.E.S.S. camera.

Waste inspection tomography (WIT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernardi, R.T.

1996-12-31

WIT is a self-sufficient mobile semitrailer for nondestructive evaluation and nondestructive assay of nuclear waste drums using x-ray and gamma-ray tomography. The recently completed Phase I included the design, fabrication, and initial testing of all WIT subsystems installed on-board the trailer. Initial test results include 2 MeV digital radiography, computed tomography, Anger camera imaging, single photon emission computed tomography, gamma-ray spectroscopy, collimated gamma scanning, and active and passive computed tomography using a 1.4 mCi source of {sup 166}Ho. These techniques were initially demonstrated on a 55-gallon phantom drum with 3 simulated waste matrices of combustibles, heterogeneous metals, and cement usingmore » check sources of gamma active isotopes such as {sup 137}Cs and {sup 133}Ba with 9-250 {mu}Ci activities. Waste matrix identification, isotopic identification, and attenuation-corrected gamma activity determination were demonstrated nondestructively and noninvasively in Phase I. Currently ongoing Phase II involves DOE site field test demonstrations at LLNL, RFETS, and INEL with real nuclear waste drums. Current WIT experience includes 55 gallon drums of cement, graphite, sludge, glass, metals, and combustibles. Thus far WIT has inspected drums with 0-20 gms of {sup 239}Pu.« less

The Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Otte, Nepomuk

The Advanced Gamma-ray Imaging System (AGIS) is a concept for the next generation of imag-ing atmospheric Cherenkov telescope arrays. It has the goal of providing an order of magnitude increase in sensitivity for Very High Energy Gamma-ray ( 100 GeV to 100 TeV) astronomy compared to currently operating arrays such as CANGAROO, HESS, MAGIC, and VERITAS. After an overview of the science such an array would enable, we discuss the development of the components of the telescope system that are required to achieve the sensitivity goal. AGIS stresses improvements in several areas of IACT technology including component reliability as well as exploring cost reduction possibilities in order to achieve its goal. We discuss alterna-tives for the telescopes and positioners: a novel Schwarzschild-Couder telescope offering a wide field of view with a relatively smaller plate scale, and possibilities for rapid slewing in order to address the search for and/or study of Gamma-ray Bursts in the VHE gamma-ray regime. We also discuss options for a high pixel count camera system providing the necessary finer solid angle per pixel and possibilities for a fast topological trigger that would offer improved realtime background rejection and lower energy thresholds.

Silicon-Based Examination of Gamma-Ray and Neutron Interactions with Solid State Materials

DTIC Science & Technology

2018-05-02

The objective of the research was to develop a fundamental understanding of the processes by which charge carriers interact in semiconductor...materials in order to aid in the development of advanced radiation detection materials. During the first three years of the research, our focus was primarily...the contact behavior and affect the charge transport. That information has been applied to single-crystal cadmium-zinc-telluride (CZT) and lead

Ultra-wide Range Gamma Detector System for Search and Locate Operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odell, D. Mackenzie Odell; Harpring, Larry J.; Moore, Frank S. Jr.

2005-10-26

Collecting debris samples following a nuclear event requires that operations be conducted from a considerable stand-off distance. An ultra-wide range gamma detector system has been constructed to accomplish both long range radiation search and close range hot sample collection functions. Constructed and tested on a REMOTEC Andros platform, the system has demonstrated reliable operation over six orders of magnitude of gamma dose from 100's of uR/hr to over 100 R/hr. Functional elements include a remotely controlled variable collimator assembly, a NaI(Tl)/photomultiplier tube detector, a proprietary digital radiation instrument, a coaxially mounted video camera, a digital compass, and both local andmore » remote control computers with a user interface designed for long range operations. Long range sensitivity and target location, as well as close range sample selection performance are presented.« less

Buried Quasars in Ultraluminous Infrared Galaxies

NASA Technical Reports Server (NTRS)

Sanders, David B.

2004-01-01

We were awarded l00OkS of INTEGRAL spacecraft time (Priority A) to observe the ultraluminous infrared galaxy (ULIG) Mrk 2273 in order io measure the integrated flux of the 20-1003 KeV gamma-Ray emission, and to use this information to search for the presence of an highly obscured active galactic nucleus (AGN). With this observation we hope to be able to better assess the role of AGN in the complete class of ULIGs and therefore to better constrain their contribution to the hard X-ray and soft gamma-ray backgrounds. Our Priority A 100 kS observation of Mrk 273 was successfully carried out during revolution #73 using 4 separate exposures with the IBIS camera during May, 2003. Our IBIS observations of Mrk 273 were successfully executed, and the source was properly centered in the Field-of-view of the detectors. We are still in the process of interpreting the IBIS gamma-ray data.

Buried Quasars in Ultra-luminous Infrared Galaxies

NASA Technical Reports Server (NTRS)

2004-01-01

We were awarded l00kS of INTEGRAL spacecraft time (Priority A) to observe the ultraluminous infrared galaxy (ULIG) Mrk 2273 in order to measure the integrated flux of the 20-1003 KeV gamma-Ray emission, and to use this information to search for the presence of an highly obscured active galactic nucleus (AGN). With this observation we hope to be able to better assess the role of AGN in the complete class of ULIGs and therefore to better constrain their contribution to the hard X-ray and soft gamma-ray backgrounds. Our Priority A 100 kS observation of Mrk 273 was successfully carried out during revolution #73 using 4 separate exposures with the IBIS camera during May, 2003. Our IBIS observations of Mrk 273 were successfully executed, and the source was properly centered in the Field-of-view of the detectors. We are still in the process of interpreting the IBIS gamma-ray data.

The Advanced Gamma-ray Imaging System (AGIS): Telescope Mechanical Designs

NASA Astrophysics Data System (ADS)

Guarino, V.; Buckley, J.; Byrum, K.; Falcone, A.; Fegan, S.; Finley, J.; Hanna, D.; Horan, D.; Kaaret, P.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Wagner, R.; Woods, M.; Vassiliev, V.

2008-04-01

The concept of a future ground-based gamma-ray observatory, AGIS, in the energy range 40 GeV-100 TeV is based on an array of sim 100 imaging atmospheric Cherenkov telescopes (IACTs). The anticipated improvements of AGIS sensitivity, angular resolution and reliability of operation impose demanding technological and cost requirements on the design of IACTs. The relatively inexpensive Davies-Cotton telescope design has been used in ground-based gamma-ray astronomy for almost fifty years and is an excellent option. We are also exploring alternative designs and in this submission we focus on the recent mechanical design of a two-mirror telescope with a Schwarzschild-Couder (SC) optical system. The mechanical structure provides support points for mirrors and camera. The design was driven by the requirement of minimizing the deflections of the mirror support structures. The structure is also designed to be able to slew in elevation and azimuth at 10 degrees/sec.

Gamma-ray spectroscopy at MHz counting rates with a compact LaBr3 detector and silicon photomultipliers for fusion plasma applications.

PubMed

Nocente, M; Rigamonti, D; Perseo, V; Tardocchi, M; Boltruczyk, G; Broslawski, A; Cremona, A; Croci, G; Gosk, M; Kiptily, V; Korolczuk, S; Mazzocco, M; Muraro, A; Strano, E; Zychor, I; Gorini, G

2016-11-01

Gamma-ray spectroscopy measurements at MHz counting rates have been carried out, for the first time, with a compact spectrometer based on a LaBr 3 scintillator and silicon photomultipliers. The instrument, which is also insensitive to magnetic fields, has been developed in view of the upgrade of the gamma-ray camera diagnostic for α particle measurements in deuterium-tritium plasmas of the Joint European Torus. Spectra were measured up to 2.9 MHz with a projected energy resolution of 3%-4% in the 3-5 MeV range, of interest for fast ion physics studies in fusion plasmas. The results reported here pave the way to first time measurements of the confined α particle profile in high power plasmas of the next deuterium-tritium campaign at the Joint European Torus.

The core of the nearby S0 galaxy NGC 7457 imaged with the HST planetary camera

NASA Technical Reports Server (NTRS)

Lauer, Tod R.; Faber, S. M.; Holtzman, Jon A.; Baum, William A.; Currie, Douglas G.; Ewald, S. P.; Groth, Edward J.; Hester, J. Jeff; Kelsall, T.

1991-01-01

A brief analysis is presented of images of the nearby S0 galaxy NGC 7457 obtained with the HST Planetary Camera. While the galaxy remains unresolved with the HST, the images reveal that any core most likely has r(c) less than 0.052 arcsec. The light distribution is consistent with a gamma = -1.0 power law inward to the resolution limit, with a possible stellar nucleus with luminosity of 10 million solar. This result represents the first observation outside the Local Group of a galaxy nucleus at this spatial resolution, and it suggests that such small, high surface brightness cores may be common.

Enhanced gamma ray sensitivity in bismuth triiodide sensors through volumetric defect control

DOE PAGES

Johns, Paul M.; Baciak, James E.; Nino, Juan C.

2016-09-02

In some of the more attractive semiconducting compounds for ambient temperature radiation detector applications are impacted by low charge collection efficiency due to the presence of point and volumetric defects. This has been particularly true in the case of BiI 3, which features very attractive properties (density, atomic number, band gap, etc.) to serve as a gamma ray detector, but has yet to demonstrate its full potential. Here, we show that by applying growth techniques tailored to reduce defects, the spectral performance of this promising semiconductor can be realized. Gamma ray spectra from >100 keV source emissions are now obtainedmore » from high quality Sb:BiI 3 bulk crystals with limited concentrations of defects (point and extended). The spectra acquired in these high quality crystals feature photopeaks with resolution of 2.2% at 662 keV. Infrared microscopy is used to compare the local microstructure between radiation sensitive and non-responsive crystals. Our work demonstrates that BiI 3 can be prepared in melt-grown detector-grade samples with superior quality and can acquire the spectra from a variety of gamma ray sources.« less

BiI 3 Crystals for High Energy Resolution Gamma-Ray Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nino, Juan C.; Baciak, James; Johns, Paul

2017-04-12

BiI 3 had been investigated for its unique properties as a layered compound semiconductor for many decades. However, despite the exceptional atomic, physical, and electronic properties of this material, good resolution gamma ray spectra had never been reported for BiI 3. The shortcomings that previously prevented BiI 3 from reaching success as a gamma ray sensor were, through this project, identified and suppressed to unlock the performance of this promising compound. Included in this work were studies on a number of methods which have, for the first time, enabled BiI 3 to exhibit spectral performance rivaling many other candidate semiconductorsmore » for room temperature gamma ray sensors. New approaches to crystal growth were explored that allow BiI 3 spectrometers to be fabricated with up to 2.2% spectral resolution at 662 keV. Fundamental studies on trap states, dopant incorporation, and polarization were performed to enhance performance of this compound. Additionally, advanced detection techniques were applied to display the capabilities of high quality BiI 3 spectrometers. Overall, through this work, BiI 3 has been revealed as a potentially transformative material for nuclear security and radiation detection sciences.« less

Wafer defect detection by a polarization-insensitive external differential interference contrast module.

PubMed

Nativ, Amit; Feldman, Haim; Shaked, Natan T

2018-05-01

We present a system that is based on a new external, polarization-insensitive differential interference contrast (DIC) module specifically adapted for detecting defects in semiconductor wafers. We obtained defect signal enhancement relative to the surrounding wafer pattern when compared with bright-field imaging. The new DIC module proposed is based on a shearing interferometer that connects externally at the output port of an optical microscope and enables imaging thin samples, such as wafer defects. This module does not require polarization optics (such as Wollaston or Nomarski prisms) and is insensitive to polarization, unlike traditional DIC techniques. In addition, it provides full control of the DIC shear and orientation, which allows obtaining a differential phase image directly on the camera (with no further digital processing) while enhancing defect detection capabilities, even if the size of the defect is smaller than the resolution limit. Our technique has the potential of future integration into semiconductor production lines.

Psychophysical Calibration of Mobile Touch-Screens for Vision Testing in the Field

NASA Technical Reports Server (NTRS)

Mulligan, Jeffrey B.

2015-01-01

The now ubiquitous nature of touch-screen displays in cell phones and tablet computers makes them an attractive option for vision testing outside of the laboratory or clinic. Accurate measurement of parameters such as contrast sensitivity, however, requires precise control of absolute and relative screen luminances. The nonlinearity of the display response (gamma) can be measured or checked using a minimum motion technique similar to that developed by Anstis and Cavanagh (1983) for the determination of isoluminance. While the relative luminances of the color primaries vary between subjects (due to factors such as individual differences in pre-retinal pigment densities), the gamma nonlinearity can be checked in the lab using a photometer. Here we compare results obtained using the psychophysical method with physical measurements for a number of different devices. In addition, we present a novel physical method using the device's built-in front-facing camera in conjunction with a mirror to jointly calibrate the camera and display. A high degree of consistency between devices is found, but some departures from ideal performance are observed. In spite of this, the effects of calibration errors and display artifacts on estimates of contrast sensitivity are found to be small.

Uncertainty propagation for SPECT/CT-based renal dosimetry in 177Lu peptide receptor radionuclide therapy

NASA Astrophysics Data System (ADS)

Gustafsson, Johan; Brolin, Gustav; Cox, Maurice; Ljungberg, Michael; Johansson, Lena; Sjögreen Gleisner, Katarina

2015-11-01

A computer model of a patient-specific clinical 177Lu-DOTATATE therapy dosimetry system is constructed and used for investigating the variability of renal absorbed dose and biologically effective dose (BED) estimates. As patient models, three anthropomorphic computer phantoms coupled to a pharmacokinetic model of 177Lu-DOTATATE are used. Aspects included in the dosimetry-process model are the gamma-camera calibration via measurement of the system sensitivity, selection of imaging time points, generation of mass-density maps from CT, SPECT imaging, volume-of-interest delineation, calculation of absorbed-dose rate via a combination of local energy deposition for electrons and Monte Carlo simulations of photons, curve fitting and integration to absorbed dose and BED. By introducing variabilities in these steps the combined uncertainty in the output quantity is determined. The importance of different sources of uncertainty is assessed by observing the decrease in standard deviation when removing a particular source. The obtained absorbed dose and BED standard deviations are approximately 6% and slightly higher if considering the root mean square error. The most important sources of variability are the compensation for partial volume effects via a recovery coefficient and the gamma-camera calibration via the system sensitivity.

SONTRAC: A High Efficiency Solar Neutron Telescope

NASA Astrophysics Data System (ADS)

Wunderer, C. B.; Macri, J.; McConnell, M. L.; Ryan, J. M.; Baltgalvis, J.; Holslin, D.; Polichar, A.; Jenkins, T.

1997-05-01

Solar flare neutron emission between 20 and 100 MeV comes from a portion of the energetic proton spectrum that is poorly sampled by both nuclear-line and pion- decay gamma rays. SONTRAC is a new generation solar neutron telescope/spectrometer consisting of densely packed, alternating orthogonal layers of scintillating plastic fibers. The fibers in both dimensions are viewed by image intensifiers and CCD cameras. Incident neutrons scatter off hydrogen in the plastic scintillator. The resulting ionizing proton tracks can be reconstructed in three dimensions using the two planar CCD track images. Two neutron-proton scatters provide sufficient information to reconstruct the energy and direction of the incident neutron. Photomultiplier tubes view the other sides of the fiber scintillator array. The signals from the PMTs are used to give an additional measure of the proton energies and to provide a trigger for the CCD cameras. Recent technological advances have allowed us to construct an affordable working prototype instrument that consists of all the essential technical elements mentioned above. We will present images of tracks produced by minimum ionizing muons and energetic neutrons. We will also present efficiency estimates for SONTRAC's ability to detect and measure gamma rays above 10 MeV.

Lithium and boron based semiconductors for thermal neutron counting

NASA Astrophysics Data System (ADS)

Kargar, Alireza; Tower, Joshua; Hong, Huicong; Cirignano, Leonard; Higgins, William; Shah, Kanai

2011-09-01

Thermal neutron detectors in planar configuration were fabricated from LiInSe2 and B2Se3 crystals grown at RMD Inc. All fabricated semiconductor devices were characterized for the current-voltage (I-V) characteristic and neutron counting measurement. Pulse height spectra were collected from 241AmBe (neutron source on all samples), as well as 137Cs and 60Co gamma ray sources. In this study, the resistivity of all crystals is reported and the collected pulse height spectra are presented for fabricated devices. Note that, the 241AmBe neutron source was custom designed with polyethylene around the source as the neutron moderator, mainly to thermalize the fast neutrons before reaching the detectors. Both LiInSe2 and B2Se3 devices showed response to thermal neutrons of the 241AmBe source.

Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector.

PubMed

Pöllänen, R; Siiskonen, T

2014-08-01

The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum. Copyright © 2014 Elsevier Ltd. All rights reserved.

An integrated radiation physics computer code system.

NASA Technical Reports Server (NTRS)

Steyn, J. J.; Harris, D. W.

1972-01-01

An integrated computer code system for the semi-automatic and rapid analysis of experimental and analytic problems in gamma photon and fast neutron radiation physics is presented. Such problems as the design of optimum radiation shields and radioisotope power source configurations may be studied. The system codes allow for the unfolding of complex neutron and gamma photon experimental spectra. Monte Carlo and analytic techniques are used for the theoretical prediction of radiation transport. The system includes a multichannel pulse-height analyzer scintillation and semiconductor spectrometer coupled to an on-line digital computer with appropriate peripheral equipment. The system is geometry generalized as well as self-contained with respect to material nuclear cross sections and the determination of the spectrometer response functions. Input data may be either analytic or experimental.

Power monitoring in space nuclear reactors using silicon carbide radiation detectors

NASA Technical Reports Server (NTRS)

Ruddy, Frank H.; Patel, Jagdish U.; Williams, John G.

2005-01-01

Space reactor power monitors based on silicon carbide (SiC) semiconductor neutron detectors are proposed. Detection of fast leakage neutrons using SiC detectors in ex-core locations could be used to determine reactor power: Neutron fluxes, gamma-ray dose rates and ambient temperatures have been calculated as a function of distance from the reactor core, and the feasibility of power monitoring with SiC detectors has been evaluated at several ex-core locations. Arrays of SiC diodes can be configured to provide the required count rates to monitor reactor power from startup to full power Due to their resistance to temperature and the effects of neutron and gamma-ray exposure, SiC detectors can be expected to provide power monitoring information for the fill mission of a space reactor.

Collimator-free photon tomography

DOEpatents

Dilmanian, F.A.; Barbour, R.L.

1998-10-06

A method of uncollimated single photon emission computed tomography includes administering a radioisotope to a patient for producing gamma ray photons from a source inside the patient. Emissivity of the photons is measured externally of the patient with an uncollimated gamma camera at a plurality of measurement positions surrounding the patient for obtaining corresponding energy spectrums thereat. Photon emissivity at the plurality of measurement positions is predicted using an initial prediction of an image of the source. The predicted and measured photon emissivities are compared to obtain differences therebetween. Prediction and comparison is iterated by updating the image prediction until the differences are below a threshold for obtaining a final prediction of the source image. 6 figs.

Photo-guided sentinel node mapping in breast cancer using marker-free photo-gamma fusion lymphoscintigraphy.

PubMed

Lee, Eun Seong; Chun, In Kook; Ha, Seunggyun; Yoon, Hai-Jeon; Jung, So-Youn; Lee, Seeyoun; Kim, Seok Won; Lee, Eun Sook; Kim, Taeyoon; Kim, Kwang Gi; Lee, Byung Il; Kim, Tae Sung; Kim, Seok-Ki

2013-03-01

Photo-gamma fusion lymphoscintigraphy (PGFLS) was developed by overlying a conventional planar gamma image on a photograph for the guidance of sentinel node biopsy. The feasibility and accuracy of PGFLS was assessed in breast cancer patients. A digital camera and a gamma camera were coordinated to obtain photograph and gamma images from the same angle. Using the distance to the object and calibration acquisition with a flat phantom and radioactive markers, PGFLS was performed both in phantom and in patients without fiducial markers. Marker-free PGFLS was verified using flat phantom, anthropomorphic phantom with markers simulating sentinel nodes and breast cancer patients. In addition, the depth of the radioactive marker or sentinel node was calculated using two gamma images taken at right angles. The feasibility and accuracy of PGFLS were assessed in terms of mismatch errors of co-registration and depth with reference to the data from SPECT/CT. The mismatch error was less than 6 mm in the flat phantom image at a distance from 50 to 62 cm without misalignment. In the anthropomorphic phantom study, co-registration error was 0.42 ± 0.29 cm; depth error was 0.51 ± 0.37 cm, which was well correlated with the reference value on SPECT/CT (x scale: R(2) = 0.99, p < 0.01; y scale: R(2) = 0.99, p < 0.01; depth: R(2) = 0.99, p < 0.01). In ten patients with breast cancer referred for lympho-SPECT/CT, PGFSL enabled photo-guided sentinel lymph node mapping with acceptable accuracy (co-registration error, 0.47 ± 0.24 cm; depth error, 1.20 ±0.41 cm). The results from PGFSL showed close correlation with those from SPECT/CT (x scale: R(2) = 0.99, p < 0.01; y scale: R(2) = 0.98, p < 0.01; depth: R(2) = 0.77, p < 0.01). The novel and convenient PGFLS technique is clinically feasible, showing acceptable accuracy and providing additional visual and quantitative information for sentinel lymph node mapping. This approach will facilitate photo-guided sentinel lymph node dissection in breast cancer.

Very High-Speed Digital Video Capability for In-Flight Use

NASA Technical Reports Server (NTRS)

Corda, Stephen; Tseng, Ting; Reaves, Matthew; Mauldin, Kendall; Whiteman, Donald

2006-01-01

digital video camera system has been qualified for use in flight on the NASA supersonic F-15B Research Testbed aircraft. This system is capable of very-high-speed color digital imaging at flight speeds up to Mach 2. The components of this system have been ruggedized and shock-mounted in the aircraft to survive the severe pressure, temperature, and vibration of the flight environment. The system includes two synchronized camera subsystems installed in fuselage-mounted camera pods (see Figure 1). Each camera subsystem comprises a camera controller/recorder unit and a camera head. The two camera subsystems are synchronized by use of an MHub(TradeMark) synchronization unit. Each camera subsystem is capable of recording at a rate up to 10,000 pictures per second (pps). A state-of-the-art complementary metal oxide/semiconductor (CMOS) sensor in the camera head has a maximum resolution of 1,280 1,024 pixels at 1,000 pps. Exposure times of the electronic shutter of the camera range from 1/200,000 of a second to full open. The recorded images are captured in a dynamic random-access memory (DRAM) and can be downloaded directly to a personal computer or saved on a compact flash memory card. In addition to the high-rate recording of images, the system can display images in real time at 30 pps. Inter Range Instrumentation Group (IRIG) time code can be inserted into the individual camera controllers or into the M-Hub unit. The video data could also be used to obtain quantitative, three-dimensional trajectory information. The first use of this system was in support of the Space Shuttle Return to Flight effort. Data were needed to help in understanding how thermally insulating foam is shed from a space shuttle external fuel tank during launch. The cameras captured images of simulated external tank debris ejected from a fixture mounted under the centerline of the F-15B aircraft. Digital video was obtained at subsonic and supersonic flight conditions, including speeds up to Mach 2 and altitudes up to 50,000 ft (15.24 km). The digital video was used to determine the structural survivability of the debris in a real flight environment and quantify the aerodynamic trajectories of the debris.

A new gamma ray imaging diagnostic for runaway electron studies at DIII-D

NASA Astrophysics Data System (ADS)

Cooper, C. M.; Pace, D. C.; Eidietis, N. W.; Paz-Soldan, C.; Commaux, N.; Shiraki, D.; Hollmann, E. M.; Moyer, R. A.; Risov, V.

2015-11-01

A new Gamma Ray Imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at DIII-D. The diagnostic is sensitive to 0.5 - 50 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE dissipation from pellet injection. The GRI consists of a lead ``pinhole camera'' mounted on the midplane with 11x11 counter-current tangential chords 20 cm wide that span the vessel. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE Bremsstrahlung radiation. Detectors operate in current saturation mode at 10 MHz, or the flux is attenuated for Pulse Height Analysis (PHA) capable of discriminating up to ~10k pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. Work supported by the US DOE under DE-AC05-00OR22725, DE-FG02-07ER54917 & DE-FC02-04ER54698.

FAST OPTICAL VARIABILITY OF A NAKED-EYE BURST-MANIFESTATION OF THE PERIODIC ACTIVITY OF AN INTERNAL ENGINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beskin, G.; Karpov, S.; Bondar, S.

We imaged the position of the naked-eye burst, GRB080319B, before, during, and after its gamma-ray activity with sub-second temporal resolution using the TORTORA wide-field camera. The burst optical prompt emission, which reached 5.3 mag, has been detected, and its periodic optical variability has been discovered in the form of four equidistant flashes with a duration of several seconds. We also detected a strong correlation (r {approx} 0.82) between optical and gamma-ray light curves with a 2 s delay of the optical emission with respect to the gamma-ray emission. The revealed temporal structure of the optical light curve in comparison withmore » the gamma-ray light curve can be interpreted in the framework of the model of shell collisions in the ejecta containing a significant neutron component. All observed emission features reflect the non-stationary behavior of the burst internal engine-supposedly, a hyperaccreting solar-mass black hole formed in the collapse of a massive stellar core.« less

A novel silicon array designed for intraoperative charged particle imaging.

PubMed

Tornai, Martin P; Patt, Bradley E; Iwanczyk, Jan S; Tull, Carolyn R; MacDonald, Lawrence R; Hoffman, Edward J

2002-11-01

A novel Si-PIN imaging array is under investigation for a charged particle (beta, positron, or alpha) sensitive intraoperative camera to be used for (residual) tumor identification during surgery. This class of collimator-less nuclear imaging device has a higher signal response for direct interactions than its scintillator-optical detector-based counterparts. Monte Carlo simulations with 635 keV betas were performed, yielding maximum and projected ranges of 1.64 and 0.55 mm in Si. Up to 90% of these betas were completely absorbed in the first 0.30 mm. Based on these results, 300 microm thick prototype Si detector arrays were designed in a 16 x 16 crossed-grid arrangement with 0.8 mm wide orthogonal strips on 1.0 mm pitch. A NIM- and CAMAC-based high-density data acquisition and processing system was used to collect the list mode data. The system was calibrated by comparisons of measured spectra to energy deposition simulations or by direct measurement of various >100 keV conversion electron or beta emitters. Mean electronic noise per strip was <3.6 keV FWHM at room temperature. When detecting positrons, which have an accompanying 511 keV annihilation background, the flood irradiated beta/gamma ratio was approximately 40, indicating that beta images could be made without the use of background rejection techniques. The intrinsic spatial resolution corresponds to the 1 x 1 mm2 pixel size, and measurements of beta emitting point and line sources yielded FWHM resolutions of 1.5 (lateral) and 2.5 mm (diagonal), respectively, with the larger widths due to particle range blurting effects. Deconvolution of the finite source size yielded intrinsic resolutions that corresponded to the image pixel size. Transmission images of circle and line phantoms with various hole sizes and pitch were resolved with either pure beta or positron irradiation without a background correction. This novel semiconductor imaging device facilitates high charged particle and low gamma sensitivity, high signal/noise ratio, and allows for compact design to potentially aid surgical guidance by providing in situ images of clinical relevance.

Single-shot pulse duration and intensity diagnostic for 10-ps MeV gamma pulses based on interferometry

NASA Astrophysics Data System (ADS)

Peng, Bo-dong; Hei, Dong-wei; Song, Yan; Liu, Jun; Zhao, Jun

2018-04-01

To measure the temporal width and the intensity evolution versus time of a MeV gamma pulse generated by a Compton Scatter Source, a time-space conversion method is proposed. This design is based on the consideration that the temporal length of the MeV pulse is proportional to the spatial length of the pulse in a certain semiconductor. The spatial length and the intensity evolution versus time of the MeV pulse can be obtained by recording the region of the refractive index change that is induced by the MeV pulse. The simulation suggests that the equivalent temporal spread of a mono-energy MeV δ pulse in a bulk semiconductor is on the order of picoseconds and does not vary significantly with photon energy and material type. According to our analysis, the excess carrier generation time, excess carrier diffusion and recombination do not significantly influence the temporal resolution of this method. The temporal response of the refractive index change to a MeV pulse is also fast enough to meet the measurement requirements. The signal generation process for measuring a 10-ps MeV pulse with a 200-fs probe beam is analyzed, revealing that the transverse size of the MeV pulse does not influence the temporal resolution of this method.

Integrated semiconductor quantum dot scintillation detector: Ultimate limit for speed and light yield

DOE PAGES

Oktyabrsky, Serge; Yakimov, Michael; Tokranov, Vadim; ...

2016-03-30

Here, a picosecond-range timing of charged particles and photons is a long-standing challenge for many high-energy physics, biophysics, medical and security applications. We present a design, technological pathway and challenges, and some properties important for realization of an ultrafast high-efficient room-temperature semiconductor scintillator based on self-assembled InAs quantum dots (QD) embedded in a GaAs matrix. Low QD density (<; 10 15 cm -3), fast (~5 ps) electron capture, luminescence peak redshifted by 0.2-0.3 eV from GaAs absorption edge with fast decay time (0.5-1 ns) along with the efficient energy transfer in the GaAs matrix (4.2 eV/pair) allows for fabrication ofmore » a semiconductor scintillator with the unsurpassed performance parameters. The major technological challenge is fabrication of a large volume (> 1 cm 3 ) of epitaxial QD medium. This requires multiple film separation and bonding, likely using separate epitaxial films as waveguides for improved light coupling. Compared to traditional inorganic scintillators, the semiconductor-QD based scintillators could have about 5x higher light yield and 20x faster decay time, opening a way to gamma detectors with the energy resolution better than 1% and sustaining counting rates MHz. Picosecond-scale timing requires segmented low-capacitance photodiodes integrated with the scintillator. For photons, the proposed detector inherently provides the depth-of-interaction information.« less

Terahertz Real-Time Imaging Uncooled Arrays Based on Antenna-Coupled Bolometers or FET Developed at CEA-Leti

NASA Astrophysics Data System (ADS)

Simoens, François; Meilhan, Jérôme; Nicolas, Jean-Alain

2015-10-01

Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz (THz) imaging are required for many application fields, such as non-destructive testing (NDT), security, quality control of food, and agricultural products industry. Two technologies of uncooled THz arrays that are being studied at CEA-Leti, i.e., bolometer and complementary metal oxide semiconductor (CMOS) field effect transistors (FET), are able to meet these requirements. This paper reminds the followed technological approaches and focuses on the latest modeling and performance analysis. The capabilities of application of these arrays to NDT and security are then demonstrated with experimental tests. In particular, high technological maturity of the THz bolometer camera is illustrated with fast scanning of large field of view of opaque scenes achieved in a complete body scanner prototype.

Protection performance evaluation regarding imaging sensors hardened against laser dazzling

NASA Astrophysics Data System (ADS)

Ritt, Gunnar; Koerber, Michael; Forster, Daniel; Eberle, Bernd

2015-05-01

Electro-optical imaging sensors are widely distributed and used for many different purposes, including civil security and military operations. However, laser irradiation can easily disturb their operational capability. Thus, an adequate protection mechanism for electro-optical sensors against dazzling and damaging is highly desirable. Different protection technologies exist now, but none of them satisfies the operational requirements without any constraints. In order to evaluate the performance of various laser protection measures, we present two different approaches based on triangle orientation discrimination on the one hand and structural similarity on the other hand. For both approaches, image analysis algorithms are applied to images taken of a standard test scene with triangular test patterns which is superimposed by dazzling laser light of various irradiance levels. The evaluation methods are applied to three different sensors: a standard complementary metal oxide semiconductor camera, a high dynamic range camera with a nonlinear response curve, and a sensor hardened against laser dazzling.

Colorimetric calibration of wound photography with off-the-shelf devices

NASA Astrophysics Data System (ADS)

Bala, Subhankar; Sirazitdinova, Ekaterina; Deserno, Thomas M.

2017-03-01

Digital cameras are often used in recent days for photographic documentation in medical sciences. However, color reproducibility of same objects suffers from different illuminations and lighting conditions. This variation in color representation is problematic when the images are used for segmentation and measurements based on color thresholds. In this paper, motivated by photographic follow-up of chronic wounds, we assess the impact of (i) gamma correction, (ii) white balancing, (iii) background unification, and (iv) reference card-based color correction. Automatic gamma correction and white balancing are applied to support the calibration procedure, where gamma correction is a nonlinear color transform. For unevenly illuminated images, non- uniform illumination correction is applied. In the last step, we apply colorimetric calibration using a reference color card of 24 patches with known colors. A lattice detection algorithm is used for locating the card. The least squares algorithm is applied for affine color calibration in the RGB model. We have tested the algorithm on images with seven different types of illumination: with and without flash using three different off-the-shelf cameras including smartphones. We analyzed the spread of resulting color value of selected color patch before and after applying the calibration. Additionally, we checked the individual contribution of different steps of the whole calibration process. Using all steps, we were able to achieve a maximum of 81% reduction in standard deviation of color patch values in resulting images comparing to the original images. That supports manual as well as automatic quantitative wound assessments with off-the-shelf devices.

Characterization of scintillator crystals for usage as prompt gamma monitors in particle therapy

NASA Astrophysics Data System (ADS)

Roemer, K.; Pausch, G.; Bemmerer, D.; Berthel, M.; Dreyer, A.; Golnik, C.; Hueso-González, F.; Kormoll, T.; Petzoldt, J.; Rohling, H.; Thirolf, P.; Wagner, A.; Wagner, L.; Weinberger, D.; Fiedler, F.

2015-10-01

Particle therapy in oncology is advantageous compared to classical radiotherapy due to its well-defined penetration depth. In the so-called Bragg peak, the highest dose is deposited; the tissue behind the cancerous area is not exposed. Different factors influence the range of the particle and thus the target area, e.g. organ motion, mispositioning of the patient or anatomical changes. In order to avoid over-exposure of healthy tissue and under-dosage of cancerous regions, the penetration depth of the particle has to be monitored, preferably already during the ongoing therapy session. The verification of the ion range can be performed using prompt gamma emissions, which are produced by interactions between projectile and tissue, and originate from the same location and time of the nuclear reaction. The prompt gamma emission profile and the clinically relevant penetration depth are correlated. Various imaging concepts based on the detection of prompt gamma rays are currently discussed: collimated systems with counting detectors, Compton cameras with (at least) two detector planes, or the prompt gamma timing method, utilizing the particle time-of-flight within the body. For each concept, the detection system must meet special requirements regarding energy, time, and spatial resolution. Nonetheless, the prerequisites remain the same: the gamma energy region (2 to 10 MeV), high counting rates and the stability in strong background radiation fields. The aim of this work is the comparison of different scintillation crystals regarding energy and time resolution for optimized prompt gamma detection.

A Major Upgrade of the H.E.S.S. Cherenkov Cameras

NASA Astrophysics Data System (ADS)

Lypova, Iryna; Giavitto, Gianluca; Ashton, Terry; Balzer, Arnim; Berge, David; Brun, Francois; Chaminade, Thomas; Delagnes, Eric; Fontaine, Gerard; Füßling, Matthias; Giebels, Berrie; Glicenstein, Jean-Francois; Gräber, Tobias; Hinton, Jim; Jahnke, Albert; Klepser, Stefan; Kossatz, Marko; Kretzschmann, Axel; Lefranc, Valentin; Leich, Holger; Lüdecke, Hartmut; Manigot, Pascal; Marandon, Vincent; Moulin, Emmanuel; de Naurois, Mathieu; Nayman, Patrick; Ohm, Stefan; Penno, Marek; Ross, Duncan; Salek, David; Schade, Markus; Schwab, Thomas; Simoni, Rachel; Stegmann, Christian; Steppa, Constantin; Thornhill, Julian; Toussnel, Francois

2017-03-01

The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in Namibia. It was built to detect Very High Energy (VHE, >100 GeV) cosmic gamma rays, and consists of four 12 m diameter Cherenkov telescopes (CT1-4), built in 2003, and a larger 28 m telescope (CT5), built in 2012. The larger mirror surface of CT5 permits to lower the energy threshold of the array down to 30 GeV. The cameras of CT1-4 are currently undergoing an extensive upgrade, with the goals of reducing their failure rate, reducing their readout dead time and improving the overall performance of the array. The entire camera electronics has been renewed from ground-up, as well as the power, ventilation and pneumatics systems, and the control and data acquisition software. Technical solutions forseen for the next-generation Cherenkov Telescope Array (CTA) observatory have been introduced, most notably the readout is based on the NECTAr analog memory chip. The camera control subsystems and the control software framework also pursue an innovative design, increasing the camera performance, robustness and flexibility. The CT1 camera has been upgraded in July 2015 and is currently taking data; CT2-4 will upgraded in Fall 2016. Together they will assure continuous operation of H.E.S.S at its full sensitivity until and possibly beyond the advent of CTA. This contribution describes the design, the testing and the in-lab and on-site performance of all components of the newly upgraded H.E.S.S. camera.

Occult Breast Cancer: Scintimammography with High-Resolution Breast-specific Gamma Camera in Women at High Risk for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rachel F. Brem; Jocelyn A. Rapelyea; , Gilat Zisman

2005-08-01

To prospectively evaluate a high-resolution breast-specific gamma camera for depicting occult breast cancer in women at high risk for breast cancer but with normal mammographic and physical examination findings. MATERIALS AND METHODS: Institutional Review Board approval and informed consent were obtained. The study was HIPAA compliant. Ninety-four high-risk women (age range, 36-78 years; mean, 55 years) with normal mammographic (Breast Imaging Reporting and Data System [BI-RADS] 1 or 2) and physical examination findings were evaluated with scintimammography. After injection with 25-30 mCi (925-1110 MBq) of technetium 99m sestamibi, patients were imaged with a high-resolution small-field-of-view breast-specific gamma camera in craniocaudalmore » and mediolateral oblique projections. Scintimammograms were prospectively classified according to focal radiotracer uptake as normal (score of 1), with no focal or diffuse uptake; benign (score of 2), with minimal patchy uptake; probably benign (score of 3), with scattered patchy uptake; probably abnormal (score of 4), with mild focal radiotracer uptake; and abnormal (score of 5), with marked focal radiotracer uptake. Mammographic breast density was categorized according to BI-RADS criteria. Patients with normal scintimammograms (scores of 1, 2, or 3) were followed up for 1 year with an annual mammogram, physical examination, and repeat scintimammography. Patients with abnormal scintimammograms (scores of 4 or 5) underwent ultrasonography (US), and those with focal hypoechoic lesions underwent biopsy. If no lesion was found during US, patients were followed up with scintimammography. Specific pathologic findings were compared with scintimammographic findings. RESULTS: Of 94 women, 78 (83%) had normal scintimammograms (score of 1, 2, or 3) at initial examination and 16 (17%) had abnormal scintimammograms (score of 4 or 5). Fourteen (88%) of the 16 patients had either benign findings at biopsy or no focal abnormality at US; in two (12%) patients, invasive carcinoma was diagnosed at US-guided biopsy (9 mm each at pathologic examination). CONCLUSION: High-resolution breast-specific scintimammography can depict small (<1-cm), mammographically occult, nonpalpable lesions in women at increased risk for breast cancer not otherwise identified at mammography or physical examination.« less

Nuclear medicine image registration by spatially noncoherent interferometry.

PubMed

Scheiber, C; Malet, Y; Sirat, G; Grucker, D

2000-02-01

This article introduces a technique for obtaining high-resolution body contour data in the same coordinate frame as that of a rotating gamma camera, using a miniature range finder, the conoscope, mounted on the camera gantry. One potential application of the technique is accurate coregistration in longitudinal brain SPECT studies, using the face of the patient (or "mask"), instead of SPECT slices, to coregister subsequent acquisitions involving the brain. Conoscopic holography is an interferometry technique that relies on spatially incoherent light interference in birefringent crystals. In this study, the conoscope was used to measure the absolute distance (Z) between a light source reflected from the skin and its observation plane. This light was emitted by a 0.2-mW laser diode. A scanning system was used to image the face during SPECT acquisition. The system consisted of a motor-driven mirror (Y axis) and the gamma-camera gantry (1 profile was obtained for each rotation step, X axis). The system was calibrated to place the conoscopic measurements and SPECT slices in the same coordinate frame. Through a simple and robust calibration of the system, the SE for measurements performed on geometric shapes was less than 2 mm, i.e., less than the actual pixel size of the SPECT data. Biometric measurements of an anthropomorphic brain phantom were within 3%-5% of actual values. The mask data were used to register images of a brain phantom and of a volunteer's brain, respectively. The rigid transformation that allowed the merging of masks by visual inspection was applied to the 2 sets of SPECT slices to perform the fusion of the data. At the cost of an additional low-cost setup integrated into the gamma-camera gantry, real-time data about the surface of the head were obtained. As in all other surface-based techniques (as opposed to volume-based techniques), this method allows the match of data independently from the dataset of interest and facilitates further registration of data from any other source. The main advantage of this technique compared with other optically based methods is the robustness of the calibration procedure and the compactness of the sensor as a result of the colinearity of the projected beam and the reflected (diffused) beams of the conoscope. Taking into account the experimental nature of this preliminary work, significant improvements in the accuracy and speed of measurements (up to 1000 points/s) are expected.

Explosive Transient Camera (ETC) Program

NASA Technical Reports Server (NTRS)

Ricker, George

1991-01-01

Since the inception of the ETC program, a wide range of new technologies was developed to support this astronomical instrument. The prototype unit was installed at ETC Site 1. The first partially automated observations were made and some major renovations were later added to the ETC hardware. The ETC was outfitted with new thermoelectrically-cooled CCD cameras and a sophisticated vacuum manifold, which, together, made the ETC a much more reliable unit than the prototype. The ETC instrumentation and building were placed under full computer control, allowing the ETC to operate as an automated, autonomous instrument with virtually no human intervention necessary. The first fully-automated operation of the ETC was performed, during which the ETC monitored the error region of the repeating soft gamma-ray burster SGR 1806-21.

ETR AND MTR COMPLEXES IN CONTEXT. CAMERA FACING NORTHERLY. FROM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ETR AND MTR COMPLEXES IN CONTEXT. CAMERA FACING NORTHERLY. FROM BOTTOM TO TOP: ETR COOLING TOWER, ELECTRICAL BUILDING AND LOW-BAY SECTION OF ETR BUILDING, HEAT EXCHANGER BUILDING (WITH U SHAPED YARD), COMPRESSOR BUILDING. MTR REACTOR SERVICES BUILDING IS ATTACHED TO SOUTH WALL OF MTR. WING A IS ATTACHED TO BALCONY FLOOR OF MTR. NEAR UPPER RIGHT CORNER OF VIEW IS MTR PROCESS WATER BUILDING. WING B IS AT FAR WEST END OF COMPLEX. NEAR MAIN GATE IS GAMMA FACILITY, WITH "COLD" BUILDINGS BEYOND: RAW WATER STORAGE TANKS, STEAM PLANT, MTR COOLING TOWER PUMP HOUSE AND COOLING TOWER. INL NEGATIVE NO. 56-4101. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

Design and Fabrication of Two-Dimensional Semiconducting Bolometer Arrays for the High Resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC-II)

NASA Technical Reports Server (NTRS)

Voellmer, George M.; Allen, Christine A.; Amato, Michael J.; Babu, Sachidananda R.; Bartels, Arlin E.; Benford, Dominic J.; Derro, Rebecca J.; Dowell, C. Darren; Harper, D. Al; Jhabvala, Murzy D.;

Design and Fabrication of Two-Dimensional Semiconducting Bolometer Arrays for the High Resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC-II)

NASA Technical Reports Server (NTRS)

Voellmer, George M.; Allen, Christine A.; Amato, Michael J.; Babu, Sachidananda R.; Bartels, Arlin E.; Benford, Dominic J.; Derro, Rebecca J.; Dowell, C. Darren; Harper, D. Al; Jhabvala, Murzy D.

2002-01-01

The High resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC II) will use almost identical versions of an ion-implanted silicon bolometer array developed at the National Aeronautics and Space Administration's Goddard Space Flight Center (GSFC). The GSFC 'Pop-up' Detectors (PUD's) use a unique folding technique to enable a 12 x 32-element close-packed array of bolometers with a filling factor greater than 95 percent. A kinematic Kevlar(trademark) suspension system isolates the 200 mK bolometers from the helium bath temperature, and GSFC - developed silicon bridge chips make electrical connection to the bolometers, while maintaining thermal isolation. The JFET preamps operate at 120 K. Providing good thermal heat sinking for these, and keeping their conduction and radiation from reaching the nearby bolometers, is one of the principal design challenges encountered. Another interesting challenge is the preparation of the silicon bolometers. They are manufactured in 32-element, planar rows using Micro Electro Mechanical Systems (MEMS) semiconductor etching techniques, and then cut and folded onto a ceramic bar. Optical alignment using specialized jigs ensures their uniformity and correct placement. The rows are then stacked to create the 12 x 32-element array. Engineering results from the first light run of SHARC II at the Caltech Submillimeter Observatory (CSO) are presented.

Evaluation of Timepix3 based CdTe photon counting detector for fully spectroscopic small animal SPECT imaging

NASA Astrophysics Data System (ADS)

Trojanova, E.; Jakubek, J.; Turecek, D.; Sykora, V.; Francova, P.; Kolarova, V.; Sefc, L.

2018-01-01

The imaging method of SPECT (Single Photon Emission Computed Tomography) is used in nuclear medicine for diagnostics of various diseases or organs malfunctions. The distribution of medically injected, inhaled, or ingested radionuclides (radiotracers) in the patient body is imaged using gamma-ray sensitive camera with suitable imaging collimator. The 3D image is then calculated by combining many images taken from different observation angles. Most of SPECT systems use scintillator based cameras. These cameras do not provide good energy resolution and do not allow efficient suppression of unwanted signals such as those caused by Compton scattering. The main goal of this work is evaluation of Timepix3 detector properties for SPECT method for functional imaging of small animals during preclinical studies. Advantageous Timepix3 properties such as energy and spatial resolution are exploited for significant image quality improvement. Preliminary measurements were performed on specially prepared plastic phantom with cavities filled by radioisotopes and then repeated with in vivo mouse sample.

ARC-1986-A86-7011

NASA Image and Video Library

1986-01-14

Range : 2.52 million miles (1.56 million miles) P-29481B/W Voyager 2 returned this photograph with all nine known Uranus rings visible from a 15 sec. exposure through the narrow angle camera. The rings are quite dark and very narrow. The most prominent and outermost of the nine, Epsilon, is seen at top. The next three in toward Uranus, called Delta, Gamma, and Eta, are much fainter and more narrow than Epsilon ring. Then come Beta and Alpha rings, and finally, the innermost grouping, known simply as the 4,5, & 6 rings. The last three are very faint and are at the limit of detection for the Voyager camera. Uranus' rings range in width from about 100 km. (60 mi.) at the widest part of the Epsilon ring, to only a few kilometers for most of the others. this iamge was processed to enhance narrow features; the bright dots are imperfections on the camera detector. The resolution scale is about 50 km. (30 mi.)

Radiation Hardening of Digital Color CMOS Camera-on-a-Chip Building Blocks for Multi-MGy Total Ionizing Dose Environments

NASA Astrophysics Data System (ADS)

Goiffon, Vincent; Rolando, Sébastien; Corbière, Franck; Rizzolo, Serena; Chabane, Aziouz; Girard, Sylvain; Baer, Jérémy; Estribeau, Magali; Magnan, Pierre; Paillet, Philippe; Van Uffelen, Marco; Mont Casellas, Laura; Scott, Robin; Gaillardin, Marc; Marcandella, Claude; Marcelot, Olivier; Allanche, Timothé

2017-01-01

The Total Ionizing Dose (TID) hardness of digital color Camera-on-a-Chip (CoC) building blocks is explored in the Multi-MGy range using 60Co gamma-ray irradiations. The performances of the following CoC subcomponents are studied: radiation hardened (RH) pixel and photodiode designs, RH readout chain, Color Filter Arrays (CFA) and column RH Analog-to-Digital Converters (ADC). Several radiation hardness improvements are reported (on the readout chain and on dark current). CFAs and ADCs degradations appear to be very weak at the maximum TID of 6 MGy(SiO2), 600 Mrad. In the end, this study demonstrates the feasibility of a MGy rad-hard CMOS color digital camera-on-a-chip, illustrated by a color image captured after 6 MGy(SiO2) with no obvious degradation. An original dark current reduction mechanism in irradiated CMOS Image Sensors is also reported and discussed.

Mary, a Pipeline to Aid Discovery of Optical Transients

NASA Astrophysics Data System (ADS)

Andreoni, I.; Jacobs, C.; Hegarty, S.; Pritchard, T.; Cooke, J.; Ryder, S.

2017-09-01

The ability to quickly detect transient sources in optical images and trigger multi-wavelength follow up is key for the discovery of fast transients. These include events rare and difficult to detect such as kilonovae, supernova shock breakout, and `orphan' Gamma-ray Burst afterglows. We present the Mary pipeline, a (mostly) automated tool to discover transients during high-cadenced observations with the Dark Energy Camera at Cerro Tololo Inter-American Observatory (CTIO). The observations are part of the `Deeper Wider Faster' programme, a multi-facility, multi-wavelength programme designed to discover fast transients, including counterparts to Fast Radio Bursts and gravitational waves. Our tests of the Mary pipeline on Dark Energy Camera images return a false positive rate of 2.2% and a missed fraction of 3.4% obtained in less than 2 min, which proves the pipeline to be suitable for rapid and high-quality transient searches. The pipeline can be adapted to search for transients in data obtained with imagers other than Dark Energy Camera.

Clinical trials of the prototype Rutherford Appleton Laboratory MWPC positron camera at the Royal Marsden Hospital

NASA Astrophysics Data System (ADS)

Flower, M. A.; Ott, R. J.; Webb, S.; Leach, M. O.; Marsden, P. K.; Clack, R.; Khan, O.; Batty, V.; McCready, V. R.; Bateman, J. E.

1988-06-01

Two clinical trials of the prototype RAL multiwire proportional chamber (MWPC) positron camera were carried out prior to the development of a clinical system with large-area detectors. During the first clinical trial, the patient studies included skeletal imaging using 18F, imaging of brain glucose metabolism using 18F FDG, bone marrow imaging using 52Fe citrate and thyroid imaging with Na 124I. Longitudinal tomograms were produced from the limited-angle data acquisition from the static detectors. During the second clinical trial, transaxial, coronal and sagittal images were produced from the multiview data acquisition. A more detailed thyroid study was performed in which the volume of the functioning thyroid tissue was obtained from the 3D PET image and this volume was used in estimating the radiation dose achieved during radioiodine therapy of patients with thyrotoxicosis. Despite the small field of view of the prototype camera, and the use of smaller than usual amounts of activity administered, the PET images were in most cases comparable with, and in a few cases visually better than, the equivalent planar view using a state-of-the-art gamma camera with a large field of view and routine radiopharmaceuticals.

Progress in the Development of CdTe and CdZnTe Semiconductor Radiation Detectors for Astrophysical and Medical Applications

PubMed Central

Sordo, Stefano Del; Abbene, Leonardo; Caroli, Ezio; Mancini, Anna Maria; Zappettini, Andrea; Ubertini, Pietro

2009-01-01

Over the last decade, cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) wide band gap semiconductors have attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon (Si) and germanium (Ge), CdTe and CdZnTe detectors show high detection efficiency and good room temperature performance and are well suited for the development of compact and reliable detection systems. In this paper, we review the current status of research in the development of CdTe and CdZnTe detectors by a comprehensive survey on the material properties, the device characteristics, the different techniques for improving the overall detector performance and some major applications. Astrophysical and medical applications are discussed, pointing out the ongoing Italian research activities on the development of these detectors. PMID:22412323

Improved scintillation detector performance via a method of enhanced layered coatings

DOE PAGES

Wakeford, Daniel Tyler; Tornga, Shawn Robert; Adams, Jillian Cathleen; ...

2016-11-16

Increasing demand for better detection performance with a simultaneous reduction in size, weight and power consumption has motivated the use of compact semiconductors as photo-converters for many gamma-ray and neutron scintillators. The spectral response of devices such as silicon avalanche photodiodes (APDs) is poorly matched to many common high-performance scintillators. We have developed a generalized analytical method that utilizes an optical reference database to match scintillator luminescence to the excitation spectrum of high quantum efficiency semiconductor detectors. This is accomplished by the fabrication and application of a series of high quantum yield, short fluorescence lifetime, wavelengthshifting coatings. Furthermore, we showmore » here a 22% increase in photoelectron collection and a 10% improvement in energy resolution when applying a layered coating to an APD-coupled, cerium-doped, yttrium oxyorthosilicate (YSO:Ce) scintillator. Wavelength-shifted radioluminescence emission and rise time analysis are also discussed.« less

Probing the defects in nano-semiconductors using positrons

NASA Astrophysics Data System (ADS)

Nambissan, P. M. G.

2011-01-01

Positron annihilation spectroscopy (PAS) is a very useful tool to study the defect properties of nanoscale materials. The ability of thermalized positrons to diffuse over to the surfaces of nanocrystallites prior to annihilation helps to explore the disordered atomic arrangement over there and is very useful in understanding the structure and properties of nanomaterials. As examples, the results of studies on FeS2 nanorods and ZnS nanoparticles are presented. In semiconductor nanoparticles, there are positron trapping sites within the grains also and these are characterised by using appropriate models on the measured positron lifetimes. We have observed vivid changes in the measured positron lifetimes and Doppler broadened gamma ray spectral lineshapes during structural transformations prompted by substitutional effects in Mn2+-doped ZnS nanorods. Interestingly, the nanoparticles did not exhibit the transformation, implying the morphologies of the nanosystems playing a decisive role. Quantum confinement effect in CdS nanoparticles was another phenomenon that could be seen through positron annihilation experiments. Coincidence Doppler broadening measurements have been useful to identify the elemental environment around the vacancy clusters that trap positrons. Recent studies on nanocrystalline oxide and sulphide semiconductors are also discussed.

Coated semiconductor devices for neutron detection

DOEpatents

Klann, Raymond T.; McGregor, Douglas S.

2002-01-01

A device for detecting neutrons includes a semi-insulated bulk semiconductor substrate having opposed polished surfaces. A blocking Schottky contact comprised of a series of metals such as Ti, Pt, Au, Ge, Pd, and Ni is formed on a first polished surface of the semiconductor substrate, while a low resistivity ("ohmic") contact comprised of metals such as Au, Ge, and Ni is formed on a second, opposed polished surface of the substrate. In one embodiment, n-type low resistivity pinout contacts comprised of an Au/Ge based eutectic alloy or multi-layered Pd/Ge/Ti/Au are also formed on the opposed polished surfaces and in contact with the Schottky and ohmic contacts. Disposed on the Schottky contact is a neutron reactive film, or coating, for detecting neutrons. The coating is comprised of a hydrogen rich polymer, such as a polyolefin or paraffin; lithium or lithium fluoride; or a heavy metal fissionable material. By varying the coating thickness and electrical settings, neutrons at specific energies can be detected. The coated neutron detector is capable of performing real-time neutron radiography in high gamma fields, digital fast neutron radiography, fissile material identification, and basic neutron detection particularly in high radiation fields.

Hard X-ray and gamma-ray imaging spectroscopy for the next solar maximum

NASA Technical Reports Server (NTRS)

Hudson, H. S.; Crannell, C. J.; Dennis, B. R.; Spicer, D. S.; Davis, J. M.; Hurford, G. J.; Lin, R. P.

1990-01-01

The objectives and principles are described of a single spectroscopic imaging package that can provide effective imaging in the hard X- and gamma-ray ranges. Called the High-Energy Solar Physics (HESP) mission instrument for solar investigation, the device is based on rotating modulation collimators with germanium semiconductor spectrometers. The instrument is planned to incorporate thick modulation plates, and the range of coverage is discussed. The optics permit the coverage of high-contrast hard X-ray images from small- and medium-sized flares with large signal-to-noise ratios. The detectors allow angular resolution of less than 1 arcsec, time resolution of less than 1 arcsec, and spectral resolution of about 1 keV. The HESP package is considered an effective and important instrument for investigating the high-energy solar events of the near-term future efficiently.

Measuring the continuity of diffusion barriers on porous films using {gamma}-ray energy spectra of escaping positronium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu Jun; Mills, Allen P. Jr.; Case, Carlye

2005-08-01

Diffusion barriers for capping porous low dielectric constant films are important for preventing metal migration into a semiconductor circuit. Using the fact that positrons implanted into a porous dielectric form ortho-positronium (o-Ps) copiously, Gidley et al. [D. W. Gidley, W. F. Frieze, T. L. Dull, J. Sun, A. F. Yee, C. V. Nguyen, and D. Y. Yoon, Appl. Phys. Lett. 76, 1282 (2000)], have been able to measure open area fractions as low as 10{sup -5} in porous dielectric film barrier layers from the increase in the ortho-positronium lifetime and intensity associated with positronium escape into vacuum. We demonstrate thatmore » it is possible to obtain comparable sensitivities by measuring the gamma-ray energy spectrum of the escaping positronium.« less

Diffraction-based optical sensor detection system for capture-restricted environments

NASA Astrophysics Data System (ADS)

Khandekar, Rahul M.; Nikulin, Vladimir V.

2008-04-01

The use of digital cameras and camcorders in prohibited areas presents a growing problem. Piracy in the movie theaters results in huge revenue loss to the motion picture industry every year, but still image and video capture may present even a bigger threat if performed in high-security locations. While several attempts are being made to address this issue, an effective solution is yet to be found. We propose to approach this problem using a very commonly observed optical phenomenon. Cameras and camcorders use CCD and CMOS sensors, which include a number of photosensitive elements/pixels arranged in a certain fashion. Those are photosites in CCD sensors and semiconductor elements in CMOS sensors. They are known to reflect a small fraction of incident light, but could also act as a diffraction grating, resulting in the optical response that could be utilized to identify the presence of such a sensor. A laser-based detection system is proposed that accounts for the elements in the optical train of the camera, as well as the eye-safety of the people who could be exposed to optical beam radiation. This paper presents preliminary experimental data, as well as the proof-of-concept simulation results.

Hyperspectral Image-Based Night-Time Vehicle Light Detection Using Spectral Normalization and Distance Mapper for Intelligent Headlight Control

PubMed Central

Kim, Heekang; Kwon, Soon; Kim, Sungho

2016-01-01

This paper proposes a vehicle light detection method using a hyperspectral camera instead of a Charge-Coupled Device (CCD) or Complementary metal-Oxide-Semiconductor (CMOS) camera for adaptive car headlamp control. To apply Intelligent Headlight Control (IHC), the vehicle headlights need to be detected. Headlights are comprised from a variety of lighting sources, such as Light Emitting Diodes (LEDs), High-intensity discharge (HID), and halogen lamps. In addition, rear lamps are made of LED and halogen lamp. This paper refers to the recent research in IHC. Some problems exist in the detection of headlights, such as erroneous detection of street lights or sign lights and the reflection plate of ego-car from CCD or CMOS images. To solve these problems, this study uses hyperspectral images because they have hundreds of bands and provide more information than a CCD or CMOS camera. Recent methods to detect headlights used the Spectral Angle Mapper (SAM), Spectral Correlation Mapper (SCM), and Euclidean Distance Mapper (EDM). The experimental results highlight the feasibility of the proposed method in three types of lights (LED, HID, and halogen). PMID:27399720

Precision of FLEET Velocimetry Using High-Speed CMOS Camera Systems

NASA Technical Reports Server (NTRS)

Peters, Christopher J.; Danehy, Paul M.; Bathel, Brett F.; Jiang, Naibo; Calvert, Nathan D.; Miles, Richard B.

2015-01-01

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 microseconds, precisions of 0.5 meters per second in air and 0.2 meters per second in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision HighSpeed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

Semiconductor neutron detectors

NASA Astrophysics Data System (ADS)

Gueorguiev, Andrey; Hong, Huicong; Tower, Joshua; Kim, Hadong; Cirignano, Leonard; Burger, Arnold; Shah, Kanai

2016-09-01

Lithium Indium Selenide (LiInSe2) has been under development in RMD Inc. and Fisk University for room temperature thermal neutron detection due to a number of promising properties. The recent advances of the crystal growth, material processing, and detector fabrication technologies allowed us to fabricate large detectors with 100 mm2 active area. The thermal neutron detection sensitivity and gamma rejection ratio (GRR) were comparable to 3He tube with 10 atm gas pressure at comparable dimensions. The synthesis, crystal growth, detector fabrication, and characterization are reported in this paper.

Bibliography of Soviet Laser Developments, Number 48 July-August 1980.

DTIC Science & Technology

1981-07-01

equilibrium and thermodvnamic properties of alloys of erbium with tellurium in the solid state. Moskovskiv Cli. Vestnik. Khimiva, no. 4, 1980, 339-344. 3...processes in a gamma laser. Sb 12, 147-163. (RZhF, 7/80, 7DI140) 292. Vysotskiy, V.I., and R.N. Kuz’min (51,2). Focusing and channeling of neutrons and...metal-nitride- oxide - semiconductor structure and a laser CRT. KE, no. 7, 1980, 1585-1588. 55 359. Soroka, S.1., and S.I. Ratnikov (0). Hologram

Semiconductor neutron detector

DOEpatents

Ianakiev, Kiril D [Los Alamos, NM; Littlewood, Peter B [Cambridge, GB; Blagoev, Krastan B [Arlington, VA; Swinhoe, Martyn T [Los Alamos, NM; Smith, James L [Los Alamos, NM; Sullivan, Clair J [Los Alamos, NM; Alexandrov, Boian S [Los Alamos, NM; Lashley, Jason Charles [Santa Fe, NM

2011-03-08

A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

Ballistic-electron-emission spectroscopy of Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures: Conduction-band offsets, transport mechanisms, and band-structure effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

OShea, J.J.; Brazel, E.G.; Rubin, M.E.

1997-07-01

We report an extensive investigation of semiconductor band-structure effects in single-barrier Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures using ballistic-electron-emission spectroscopy (BEES). The transport mechanisms in these single-barrier structures were studied systematically as a function of temperature and Al composition over the full compositional range (0{le}x{le}1). The initial ({Gamma}) BEES thresholds for Al{sub x}Ga{sub 1{minus}x}As single barriers with 0{le}x{le}0.42 were extracted using a model which includes the complete transmission probability of the metal-semiconductor interface and the semiconductor heterostructure. Band offsets measured by BEES are in good agreement with previous measurements by other techniques which demonstrates the accuracy of this technique. BEES measurements atmore » 77 K give the same band-offset values as at room temperature. When a reverse bias is applied to the heterostructures, the BEES thresholds shift to lower voltages in good agreement with the expected bias-induced band-bending. In the indirect band-gap regime ({ital x}{gt}0.45), spectra show a weak ballistic-electron-emission microscopy current contribution due to intervalley scattering through Al{sub x}Ga{sub 1{minus}x}As {ital X} valley states. Low-temperature spectra show a marked reduction in this intervalley current component, indicating that intervalley phonon scattering at the GaAs/Al{sub x}Ga{sub 1{minus}x}As interface produces a significant fraction of this{ital X} valley current. A comparison of the BEES thresholds with the expected composition dependence of the Al{sub x}Ga{sub 1{minus}x}As {Gamma}, {ital L}, and {ital X} points yields good agreement over the entire composition range. {copyright} {ital 1997} {ital The American Physical Society}« less

Photon counting readout pixel array in 0.18-μm CMOS technology for on-line gamma-ray imaging of 103palladium seeds for permanent breast seed implant (PBSI) brachytherapy

NASA Astrophysics Data System (ADS)

Goldan, A. H.; Karim, K. S.; Reznik, A.; Caldwell, C. B.; Rowlands, J. A.

2008-03-01

Permanent breast seed implant (PBSI) brachytherapy technique was recently introduced as an alternative to high dose rate (HDR) brachytherapy and involves the permanent implantation of radioactive 103Palladium seeds into the surgical cavity of the breast for cancer treatment. To enable accurate seed implantation, this research introduces a gamma camera based on a hybrid amorphous selenium detector and CMOS readout pixel architecture for real-time imaging of 103Palladium seeds during the PBSI procedure. A prototype chip was designed and fabricated in 0.18-μm n-well CMOS process. We present the experimental results obtained from this integrated photon counting readout pixel.

A comprehensive experimental characterization of the iPIX gamma imager

NASA Astrophysics Data System (ADS)

Amgarou, K.; Paradiso, V.; Patoz, A.; Bonnet, F.; Handley, J.; Couturier, P.; Becker, F.; Menaa, N.

2016-08-01

The results of more than 280 different experiments aimed at exploring the main features and performances of a newly developed gamma imager, called iPIX, are summarized in this paper. iPIX is designed to quickly localize radioactive sources while estimating the ambient dose equivalent rate at the measurement point. It integrates a 1 mm thick CdTe detector directly bump-bonded to a Timepix chip, a tungsten coded-aperture mask, and a mini RGB camera. It also represents a major technological breakthrough in terms of lightness, compactness, usability, response sensitivity, and angular resolution. As an example of its key strengths, an 241Am source with a dose rate of only few nSv/h can be localized in less than one minute.

Neutron flux measurements using scintillator-photodiode-preamplifier system and new types of scintillators

NASA Astrophysics Data System (ADS)

Ryzhikov, Vladimir D.; Burachas, S. F.; Volkov, V. G.; Danshin, Evgeniy A.; Lisetskaya, Elena K.; Piven, L. A.; Svishch, Vladimir M.; Chernikov, Vyacheslav V.; Filimonov, A. E.

1997-02-01

After the Chernobyl catastrophe among the problems of current concern a question arose of detection of 'hot' particles formed from plutonium alloys with carbon, nitrogen, silicon, etc. For this purpose, the instruments are needed, which would be able to detect not only alpha- particles and low energy gamma-radiation, but also neutrons and high energy gamma-quanta from ((alpha) , n(gamma) ) - reactions. At present for each kind of radiation detectors of different types are used. A general drawback of all these instruments is their narrow dynamic range of dose rates and energies, and especially impossibility to registrate n-flux in condition large background activity gamma-rays nuclei, which makes each of them applicable only under certain specific conditions. For detection of 'hot' particles, oxide and semiconductor scintillators were used, which contained elements with large capture cross section for thermal neutrons. In this paper we try to determine possibilities and limitations of solid-state neutron detectors based on CdS(Te), ZnSe(Te), CdWO4 (CWO), Gd2SiO5 (GSO) scintillators developed and produced by the Science and Technology Center for Radiation Instruments of the Institute for Single Crystals. The instruments developed by Center are based preferable on a very promising system 'scintillator- photodiode-preamplifier' matched with modern computer data processing techniques.

Potential of SeHCAT retention as an indicator of terminal ileal involvement in inflammatory bowel disease.

PubMed

Holdstock, G; Phillips, G; Hames, T K; Condon, B R; Fleming, J S; Smith, C L; Ackery, D M

1985-01-01

The absorption of 75Se-23-selena-25-homotaurocholate (SeHCAT) was compared with vitamin-B12 absorption and conventional radiography in 44 patients with inflammatory bowel disease. The retention of SeHCAT was normal in 11 patients with ulcerative colitis but was abnormally low in 9 patients with terminal-ileal resection, 9 out of 14 patients with small-bowel Crohn's disease and in 2 out of 10 patients with Crohn's colitis. The 5 patients with small-bowel Crohn's disease and normal retention had either inactive disease or no radiological evidence of terminal ileal involvement. Measurements of the absorption of vitamin B12 did not discriminate between these groups, and there was very poor correlation between B12 and SeHCAT absorption (r = 0.506, P less than 0.05). There was extremely good correlation of SeHCAT retention measured using a wholebody counter with that measured using an uncollimated gamma camera (r = 0.96, P less than 0.001). The results suggest that SeHCAT retention may prove complementary to conventional methods of assessing small-bowel disease in patients with inflammatory bowel disease. As measurement by gamma camera is feasible, this test can be used in most departments of nuclear medicine.

Compton Camera and Prompt Gamma Ray Timing: Two Methods for In Vivo Range Assessment in Proton Therapy

PubMed Central

Hueso-González, Fernando; Fiedler, Fine; Golnik, Christian; Kormoll, Thomas; Pausch, Guntram; Petzoldt, Johannes; Römer, Katja E.; Enghardt, Wolfgang

2016-01-01

Proton beams are promising means for treating tumors. Such charged particles stop at a defined depth, where the ionization density is maximum. As the dose deposit beyond this distal edge is very low, proton therapy minimizes the damage to normal tissue compared to photon therapy. Nevertheless, inherent range uncertainties cast doubts on the irradiation of tumors close to organs at risk and lead to the application of conservative safety margins. This constrains significantly the potential benefits of protons over photons. In this context, several research groups are developing experimental tools for range verification based on the detection of prompt gammas, a nuclear by-product of the proton irradiation. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf, detector components have been characterized in realistic radiation environments as a step toward a clinical Compton camera. On the one hand, corresponding experimental methods and results obtained during the ENTERVISION training network are reviewed. On the other hand, a novel method based on timing spectroscopy has been proposed as an alternative to collimated imaging systems. The first tests of the timing method at a clinical proton accelerator are summarized, its applicability in a clinical environment for challenging the current safety margins is assessed, and the factors limiting its precision are discussed. PMID:27148473

Optical artefact characterization and correction in volumetric scintillation dosimetry

PubMed Central

Robertson, Daniel; Hui, Cheukkai; Archambault, Louis; Mohan, Radhe; Beddar, Sam

2014-01-01

The goals of this study were (1) to characterize the optical artefacts affecting measurement accuracy in a volumetric liquid scintillation detector, and (2) to develop methods to correct for these artefacts. The optical artefacts addressed were photon scattering, refraction, camera perspective, vignetting, lens distortion, the lens point spread function, stray radiation, and noise in the camera. These artefacts were evaluated by theoretical and experimental means, and specific correction strategies were developed for each artefact. The effectiveness of the correction methods was evaluated by comparing raw and corrected images of the scintillation light from proton pencil beams against validated Monte Carlo calculations. Blurring due to the lens and refraction at the scintillator tank-air interface were found to have the largest effect on the measured light distribution, and lens aberrations and vignetting were important primarily at the image edges. Photon scatter in the scintillator was not found to be a significant source of artefacts. The correction methods effectively mitigated the artefacts, increasing the average gamma analysis pass rate from 66% to 98% for gamma criteria of 2% dose difference and 2 mm distance to agreement. We conclude that optical artefacts cause clinically meaningful errors in the measured light distribution, and we have demonstrated effective strategies for correcting these optical artefacts. PMID:24321820

3D tomographic imaging with the γ-eye planar scintigraphic gamma camera

NASA Astrophysics Data System (ADS)

Tunnicliffe, H.; Georgiou, M.; Loudos, G. K.; Simcox, A.; Tsoumpas, C.

2017-11-01

γ-eye is a desktop planar scintigraphic gamma camera (100 mm × 50 mm field of view) designed by BET Solutions as an affordable tool for dynamic, whole body, small-animal imaging. This investigation tests the viability of using γ-eye for the collection of tomographic data for 3D SPECT reconstruction. Two software packages, QSPECT and STIR (software for tomographic image reconstruction), have been compared. Reconstructions have been performed using QSPECT’s implementation of the OSEM algorithm and STIR’s OSMAPOSL (Ordered Subset Maximum A Posteriori One Step Late) and OSSPS (Ordered Subsets Separable Paraboloidal Surrogate) algorithms. Reconstructed images of phantom and mouse data have been assessed in terms of spatial resolution, sensitivity to varying activity levels and uniformity. The effect of varying the number of iterations, the voxel size (1.25 mm default voxel size reduced to 0.625 mm and 0.3125 mm), the point spread function correction and the weight of prior terms were explored. While QSPECT demonstrated faster reconstructions, STIR outperformed it in terms of resolution (as low as 1 mm versus 3 mm), particularly when smaller voxel sizes were used, and in terms of uniformity, particularly when prior terms were used. Little difference in terms of sensitivity was seen throughout.

Organic-on-silicon complementary metal-oxide-semiconductor colour image sensors.

PubMed

Lim, Seon-Jeong; Leem, Dong-Seok; Park, Kyung-Bae; Kim, Kyu-Sik; Sul, Sangchul; Na, Kyoungwon; Lee, Gae Hwang; Heo, Chul-Joon; Lee, Kwang-Hee; Bulliard, Xavier; Satoh, Ryu-Ichi; Yagi, Tadao; Ro, Takkyun; Im, Dongmo; Jung, Jungkyu; Lee, Myungwon; Lee, Tae-Yon; Han, Moon Gyu; Jin, Yong Wan; Lee, Sangyoon

2015-01-12

Complementary metal-oxide-semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor.

Organic-on-silicon complementary metal–oxide–semiconductor colour image sensors

PubMed Central

Lim, Seon-Jeong; Leem, Dong-Seok; Park, Kyung-Bae; Kim, Kyu-Sik; Sul, Sangchul; Na, Kyoungwon; Lee, Gae Hwang; Heo, Chul-Joon; Lee, Kwang-Hee; Bulliard, Xavier; Satoh, Ryu-Ichi; Yagi, Tadao; Ro, Takkyun; Im, Dongmo; Jung, Jungkyu; Lee, Myungwon; Lee, Tae-Yon; Han, Moon Gyu; Jin, Yong Wan; Lee, Sangyoon

2015-01-01

Complementary metal–oxide–semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor. PMID:25578322

Exploration of the Townsend regime by discharge light emission in a gas discharge device

NASA Astrophysics Data System (ADS)

Hilal Yucel, Kurt

2014-01-01

The Townsend discharge mechanism has been explored in a planar microelectronic gas discharge device (MGDD) with different applied voltages U and interelectrode distance d under various pressures in air. The anode and the cathode of the MGDD are formed by a transparent SnO2 covered glass and a GaAs semiconductor, respectively. In the experiments, the discharge is found to be unstable just below the breakdown voltage Ub, whereas the discharge passes through a homogeneous stable Townsend mode beyond the breakdown voltage. The measurements are made by an electrical circuit and a CCD camera by recording the currents and light emission (LE) intensities. The intensity profiles, which are converted from the 3D light emission images along the semiconductor diameter, have been analysed for different system parameters. Different instantaneous conductivity σt regimes are found below and beyond the Townsend region. These regimes govern the current and spatio-temporal LE stabilities in the plasma system. It has been proven that the stable LE region increases up to 550 Torr as a function of pressure for small d. If the active area of the semiconductor becomes larger and the interlectrode distance d becomes smaller, the stable LE region stays nearly constant with pressure.

Development of a 32-detector CdTe matrix for the SVOM ECLAIRs x/gamma camera: tests results of first flight models

NASA Astrophysics Data System (ADS)

Lacombe, K.; Dezalay, J.-P.; Houret, B.; Amoros, C.; Atteia, J.-L.; Aubaret, K.; Billot, M.; Bordon, S.; Cordier, B.; Delaigue, S.; Galliano, M.; Gevin, O.; Godet, O.; Gonzalez, F.; Guillemot, Ph.; Limousin, O.; Mercier, K.; Nasser, G.; Pons, R.; Rambaud, D.; Ramon, P.; Waegebaert, V.

2016-07-01

ECLAIRs, a 2-D coded-mask imaging camera on-board the Sino-French SVOM space mission, will detect and locate gamma-ray bursts in near real time in the 4 - 150 keV energy band in a large field of view. The design of ECLAIRs has been driven by the objective to reach an unprecedented low-energy threshold of 4 keV. The detection plane is an assembly of 6400 Schottky CdTe detectors of size 4x4x1 mm3, biased from -200V to -500V and operated at -20°C. The low-energy threshold is achieved thanks to an innovative hybrid module composed of a thick film ceramic holding 32 CdTe detectors ("Detectors Ceramics"), associated to an HTCC ceramic housing a low-noise 32-channel ASIC ("ASIC Ceramics"). We manage the coupling between Detectors Ceramics and ASIC Ceramics in order to achieve the best performance and ensure the uniformity of the detection plane. In this paper, we describe the complete hybrid XRDPIX, of which 50 flight models have been manufactured by the SAGEM company. Afterwards, we show test results obtained on Detectors Ceramics, on ASIC Ceramics and on the modules once assembled. Then, we compare and confront detectors leakage currents and ASIC ENC with the energy threshold values and FWHM measured on XRDPIX modules at the temperature of -20°C by using a calibrated radioactive source of 241Am. Finally, we study the homogeneity of the spectral properties of the 32-detector hybrid matrices and we conclude on general performance of more than 1000 detection channels which may reach the lowenergy threshold of 4 keV required for the future ECLAIRs space camera.

Light-Trap: a SiPM upgrade for VHE astronomy and beyond

NASA Astrophysics Data System (ADS)

Ward, J. E.; Cortina, J.; Guberman, D.

2016-11-01

Ground-based gamma-ray astronomy in the Very High Energy (VHE, E > 100 GeV) regime has fast become one of the most interesting and productive sub-fields of astrophysics today. Utilizing the Imaging Atmospheric Cherenkov Technique (IACT) to reconstruct the energy and direction of incoming gamma-ray photons from the universe, several source-classes have been revealed by previous and current generations of IACT telescopes (e.g. Whipple, MAGIC, HESS and VERITAS). The next generation pointing IACT experiment, the Cherenkov Telescope Array (CTA), will provide increased sensitivity across a wider energy range and with better angular resolution. With the development of CTA, the future of IACT pointing arrays is being directed towards having more and more telescopes (and hence cameras), and therefore the need to develop low-cost pixels with acceptable light-collection efficiency is clear. One of the primary paths to the above goal is to replace Photomultiplier Tubes (PMTs) with Silicon-PMs (SiPMs) as the pixels in IACT telescope cameras. However SiPMs are not yet mature enough to replace PMTs for several reasons: sensitivity to unwanted longer wavelengths while lacking sensitivity at short wavelengths, small physical area, high cost, optical cross-talk and dark rates. Here we propose a novel method to build relatively low-cost SiPM-based pixels utilising a disk of wavelength-shifting material, which overcomes some of these drawbacks by collecting light over a larger area than standard SiPMs and improving sensitivity to shorter wavelengths while reducing background. We aim to optimise the design of such pixels, integrating them into an actual 7-pixel cluster which will be inserted into a MAGIC camera and tested during real observations. Results of simulations, laboratory measurements and the current status of the cluster design and development will be presented.

Study on the Spatial Resolution of Single and Multiple Coincidences Compton Camera

NASA Astrophysics Data System (ADS)

Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

2012-10-01

In this paper we study the image resolution that can be obtained from the Multiple Coincidences Compton Camera (MCCC). The principle of MCCC is based on a simultaneous acquisition of several gamma-rays emitted in cascade from a single nucleus. Contrary to a standard Compton camera, MCCC can theoretically provide the exact location of a radioactive source (based only on the identification of the intersection point of three cones created by a single decay), without complicated tomographic reconstruction. However, practical implementation of the MCCC approach encounters several problems, such as low detection sensitivities result in very low probability of coincident triple gamma-ray detection, which is necessary for the source localization. It is also important to evaluate how the detection uncertainties (finite energy and spatial resolution) influence identification of the intersection of three cones, thus the resulting image quality. In this study we investigate how the spatial resolution of the reconstructed images using the triple-cone reconstruction (TCR) approach compares to images reconstructed from the same data using standard iterative method based on single-cone. Results show, that FWHM for the point source reconstructed with TCR was 20-30% higher than the one obtained from the standard iterative reconstruction based on expectation maximization (EM) algorithm and conventional single-cone Compton imaging. Finite energy and spatial resolutions of the MCCC detectors lead to errors in conical surfaces definitions (“thick” conical surfaces) which only amplify in image reconstruction when intersection of three cones is being sought. Our investigations show that, in spite of being conceptually appealing, the identification of triple cone intersection constitutes yet another restriction of the multiple coincidence approach which limits the image resolution that can be obtained with MCCC and TCR algorithm.

Nuclear Radiation Degradation Study on HD Camera Based on CMOS Image Sensor at Different Dose Rates.

PubMed

Wang, Congzheng; Hu, Song; Gao, Chunming; Feng, Chang

2018-02-08

In this work, we irradiated a high-definition (HD) industrial camera based on a commercial-off-the-shelf (COTS) CMOS image sensor (CIS) with Cobalt-60 gamma-rays. All components of the camera under test were fabricated without radiation hardening, except for the lens. The irradiation experiments of the HD camera under biased conditions were carried out at 1.0, 10.0, 20.0, 50.0 and 100.0 Gy/h. During the experiment, we found that the tested camera showed a remarkable degradation after irradiation and differed in the dose rates. With the increase of dose rate, the same target images become brighter. Under the same dose rate, the radiation effect in bright area is lower than that in dark area. Under different dose rates, the higher the dose rate is, the worse the radiation effect will be in both bright and dark areas. And the standard deviations of bright and dark areas become greater. Furthermore, through the progressive degradation analysis of the captured image, experimental results demonstrate that the attenuation of signal to noise ratio (SNR) versus radiation time is not obvious at the same dose rate, and the degradation is more and more serious with increasing dose rate. Additionally, the decrease rate of SNR at 20.0, 50.0 and 100.0 Gy/h is far greater than that at 1.0 and 10.0 Gy/h. Even so, we confirm that the HD industrial camera is still working at 10.0 Gy/h during the 8 h of measurements, with a moderate decrease of the SNR (5 dB). The work is valuable and can provide suggestion for camera users in the radiation field.