Abstract ID: 242 Simulation of a Fast Timing Micro-Pattern Gaseous Detector for TOF-PET.

PubMed

Radogna, Raffaella; Verwilligen, Piet

2018-01-01

Micro-Pattern Gas Detectors (MPGDs) are a new generation of gaseous detectors that have been developed thanks to advances in micro-structure technology. The main features of the MPGDs are: high rate capability (>50 MHz/cm 2 ); excellent spatial resolution (down to 50 μm); good time resolution (down to 3 ns); reduced radiation length, affordable costs, and possible flexible geometries. A new detector layout has been recently proposed that aims at combining both the high spatial resolution and high rate capability (100 MHz/cm 2 ) of the current state-of-the-art MPGDs with a high time resolution. This new type of MPGD is named the Fast Timing MPGD (FTM) detector [1,2]. The FTM developed for detecting charged particles can potentially reach sub-millimeter spatial resolution and 100 ps time resolution. This contribution introduces a Fast Timing MPGD technology optimized to detect photons, as an innovative PET imaging detector concept and emphases the importance of full detector simulation to guide the design of the detector geometry. The design and development of a new FTM, combining excellent time and spatial resolution, while exploiting the advantages of a reasonable energy resolution, will be a boost for the design of affordable TOF-PET scanner with improved image contrast. The use of such an affordable gas detector allows to instrument large areas in a cost-effective way, and to increase in image contrast for shorter scanning times (lowering the risk for the patient) and better diagnosis of the disease. In this report a dedicated simulation study is performed to optimize the detector design in the contest of the INFN project MPGD-Fatima. Results are obtained with ANSYS, COMSOL, GARFIELD++ and GEANT4 simulation tools. The final detector layout will be trade-off between fast time and good energy resolution. Copyright © 2017.

High resolution micro-CT of low attenuating organic materials using large area photon-counting detector

NASA Astrophysics Data System (ADS)

Kumpová, I.; Vavřík, D.; Fíla, T.; Koudelka, P.; Jandejsek, I.; Jakůbek, J.; Kytýř, D.; Zlámal, P.; Vopálenský, M.; Gantar, A.

2016-02-01

To overcome certain limitations of contemporary materials used for bone tissue engineering, such as inflammatory response after implantation, a whole new class of materials based on polysaccharide compounds is being developed. Here, nanoparticulate bioactive glass reinforced gelan-gum (GG-BAG) has recently been proposed for the production of bone scaffolds. This material offers promising biocompatibility properties, including bioactivity and biodegradability, with the possibility of producing scaffolds with directly controlled microgeometry. However, to utilize such a scaffold with application-optimized properties, large sets of complex numerical simulations using the real microgeometry of the material have to be carried out during the development process. Because the GG-BAG is a material with intrinsically very low attenuation to X-rays, its radiographical imaging, including tomographical scanning and reconstructions, with resolution required by numerical simulations might be a very challenging task. In this paper, we present a study on X-ray imaging of GG-BAG samples. High-resolution volumetric images of investigated specimens were generated on the basis of micro-CT measurements using a large area flat-panel detector and a large area photon-counting detector. The photon-counting detector was composed of a 010× 1 matrix of Timepix edgeless silicon pixelated detectors with tiling based on overlaying rows (i.e. assembled so that no gap is present between individual rows of detectors). We compare the results from both detectors with the scanning electron microscopy on selected slices in transversal plane. It has been shown that the photon counting detector can provide approx. 3× better resolution of the details in low-attenuating materials than the integrating flat panel detectors. We demonstrate that employment of a large area photon counting detector is a good choice for imaging of low attenuating materials with the resolution sufficient for numerical simulations.

Development of a combined microSPECT/CT system for small animal imaging

NASA Astrophysics Data System (ADS)

Sun, Mingshan

Modern advances in the biomedical sciences have placed increased attention on small animals such as mice and rats as models of human biology and disease in biological research and pharmaceutical development. Their small size and fast breeding rate, their physiologic similarity to human, and, more importantly, the availability of sophisticated genetic manipulations, all have made mice and rats the laboratory mammals of choice in these experimental studies. However, the increased use of small animals in biomedical research also calls for new instruments that can measure the anatomic and metabolic information noninvasively with adequate spatial resolution and measurement sensitivity to facilitate these studies. This dissertation describes the engineering development of a combined single photon emission computed tomography (SPECT) and X-ray computed tomography (CT) system dedicated for small animals imaging. The system aims to obtain both the anatomic and metabolic images with submillimeter spatial resolution in a way that the data can be correlated to provide improved image quality and to offer more complete biological evaluation for biomedical studies involving small animals. The project requires development of complete microSPECT and microCT subsystems. Both subsystems are configured with a shared gantry and animal bed with integrated instrumentation for data acquisition and system control. The microCT employs a microfocus X-ray tube and a CCD-based detector for low noise, high resolution imaging. The microSPECT utilizes three semiconductor detectors coupled with pinhole collimators. A significant contribution of this dissertation project is the development of iterative algorithms with geometrical compensation that allows radionuclide images to be reconstructed at submillimeter spatial resolution, but with significantly higher detection efficiency than conventional methods. Both subsystems are capable of helical scans, offering lengthened field of view and improved axial resolution. System performance of both modalities is characterized with phantoms and animals. The microSPECT shows 0.6 mm resolution and 60 cps/MBq detection efficiency for imaging mice with 0.5 mm pinholes. The microCT achieves 120 mum spatial resolution on detector but with a relatively low detective quantum efficiency of 0.2 at the zero frequency. The combined system demonstrates a flexible platform for instrumentation development and a valuable tool for biomedical research. In summary, this dissertation describes the development of a combined SPECT/CT system for imaging the physiological function and anatomical structure in small animals.

High-contrast X-ray micro-radiography and micro-CT of ex-vivo soft tissue murine organs utilizing ethanol fixation and large area photon-counting detector

PubMed Central

Dudak, Jan; Zemlicka, Jan; Karch, Jakub; Patzelt, Matej; Mrzilkova, Jana; Zach, Petr; Hermanova, Zuzana; Kvacek, Jiri; Krejci, Frantisek

2016-01-01

Using dedicated contrast agents high-quality X-ray imaging of soft tissue structures with isotropic micrometre resolution has become feasible. This technique is frequently titled as virtual histology as it allows production of slices of tissue without destroying the sample. The use of contrast agents is, however, often an irreversible time-consuming procedure and despite the non-destructive principle of X-ray imaging, the sample is usually no longer usable for other research methods. In this work we present the application of recently developed large-area photon counting detector for high resolution X-ray micro-radiography and micro-tomography of whole ex-vivo ethanol-preserved mouse organs. The photon counting detectors provide dark-current-free quantum-counting operation enabling acquisition of data with virtually unlimited contrast-to-noise ratio (CNR). Thanks to the very high CNR even ethanol-only preserved soft-tissue samples without addition of any contrast agent can be visualized in great detail. As ethanol preservation is one of the standard steps of tissue fixation for histology, the presented method can open a way for widespread use of micro-CT with all its advantages for routine 3D non-destructive soft-tissue visualisation. PMID:27461900

Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination

NASA Astrophysics Data System (ADS)

Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

2014-12-01

A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 μm and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

Device and Method of Scintillating Quantum Dots for Radiation Imaging

NASA Technical Reports Server (NTRS)

Burke, Eric R. (Inventor); DeHaven, Stanton L. (Inventor); Williams, Phillip A. (Inventor)

2017-01-01

A radiation imaging device includes a radiation source and a micro structured detector comprising a material defining a surface that faces the radiation source. The material includes a plurality of discreet cavities having openings in the surface. The detector also includes a plurality of quantum dots disclosed in the cavities. The quantum dots are configured to interact with radiation from the radiation source, and to emit visible photons that indicate the presence of radiation. A digital camera and optics may be used to capture images formed by the detector in response to exposure to radiation.

High Resolution PET with 250 micrometer LSO Detectors and Adaptive Zoom

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

Cherry, Simon R.; Qi, Jinyi

2012-01-08

There have been impressive improvements in the performance of small-animal positron emission tomography (PET) systems since their first development in the mid 1990s, both in terms of spatial resolution and sensitivity, which have directly contributed to the increasing adoption of this technology for a wide range of biomedical applications. Nonetheless, current systems still are largely dominated by the size of the scintillator elements used in the detector. Our research predicts that developing scintillator arrays with an element size of 250 {micro}m or smaller will lead to an image resolution of 500 {micro}m when using 18F- or 64Cu-labeled radiotracers, giving amore » factor of 4-8 improvement in volumetric resolution over the highest resolution research systems currently in existence. This proposal had two main objectives: (i) To develop and evaluate much higher resolution and efficiency scintillator arrays that can be used in the future as the basis for detectors in a small-animal PET scanner where the spatial resolution is dominated by decay and interaction physics rather than detector size. (ii) To optimize one such high resolution, high sensitivity detector and adaptively integrate it into the existing microPET II small animal PET scanner as a 'zoom-in' detector that provides higher spatial resolution and sensitivity in a limited region close to the detector face. The knowledge gained from this project will provide valuable information for building future PET systems with a complete ring of very high-resolution detector arrays and also lay the foundations for utilizing high-resolution detectors in combination with existing PET systems for localized high-resolution imaging.« less

Image analysis of pulmonary nodules using micro CT

NASA Astrophysics Data System (ADS)

Niki, Noboru; Kawata, Yoshiki; Fujii, Masashi; Kakinuma, Ryutaro; Moriyama, Noriyuki; Tateno, Yukio; Matsui, Eisuke

2001-07-01

We are developing a micro-computed tomography (micro CT) system for imaging pulmonary nodules. The purpose is to enhance the physician performance in accessing the micro- architecture of the nodule for classification between malignant and benign nodules. The basic components of the micro CT system consist of microfocus X-ray source, a specimen manipulator, and an image intensifier detector coupled to charge-coupled device (CCD) camera. 3D image reconstruction was performed by the slice. A standard fan- beam convolution and backprojection algorithm was used to reconstruct the center plane intersecting the X-ray source. The preprocessing of the 3D image reconstruction included the correction of the geometrical distortions and the shading artifact introduced by the image intensifier. The main advantage of the system is to obtain a high spatial resolution which ranges between b micrometers and 25 micrometers . In this work we report on preliminary studies performed with the micro CT for imaging resected tissues of normal and abnormal lung. Experimental results reveal micro architecture of lung tissues, such as alveolar wall, septal wall of pulmonary lobule, and bronchiole. From the results, the micro CT system is expected to have interesting potentials for high confidential differential diagnosis.

High-contrast X-ray micro-tomography of low attenuation samples using large area hybrid semiconductor pixel detector array of 10 × 5 Timepix chips

NASA Astrophysics Data System (ADS)

Karch, J.; Krejci, F.; Bartl, B.; Dudak, J.; Kuba, J.; Kvacek, J.; Zemlicka, J.

2016-01-01

State-of-the-art hybrid pixel semiconductor detectors provide excellent imaging properties such as unlimited dynamic range, high spatial resolution, high frame rate and energy sensitivity. Nevertheless, a limitation in the use of these devices for imaging has been the small sensitive area of a few square centimetres. In the field of microtomography we make use of a large area pixel detector assembled from 50 Timepix edgeless chips providing fully sensitive area of 14.3 × 7.15 cm2. We have successfully demonstrated that the enlargement of the sensitive area enables high-quality tomographic measurements of whole objects with high geometrical magnification without any significant degradation in resulting reconstructions related to the chip tilling and edgeless sensor technology properties. The technique of micro-tomography with the newly developed large area detector is applied for samples formed by low attenuation, low contrast materials such a seed from Phacelia tanacetifolia, a charcoalified wood sample and a beeswax seal sample.

Region-of-interest image reconstruction in circular cone-beam microCT

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

Cho, Seungryong; Bian, Junguo; Pelizzari, Charles A.

2007-12-15

Cone-beam microcomputed tomography (microCT) is one of the most popular choices for small animal imaging which is becoming an important tool for studying animal models with transplanted diseases. Region-of-interest (ROI) imaging techniques in CT, which can reconstruct an ROI image from the projection data set of the ROI, can be used not only for reducing imaging-radiation exposure to the subject and scatters to the detector but also for potentially increasing spatial resolution of the reconstructed images. Increasing spatial resolution in microCT images can facilitate improved accuracy in many assessment tasks. A method proposed previously for increasing CT image spatial resolutionmore » entails the exploitation of the geometric magnification in cone-beam CT. Due to finite detector size, however, this method can lead to data truncation for a large geometric magnification. The Feldkamp-Davis-Kress (FDK) algorithm yields images with artifacts when truncated data are used, whereas the recently developed backprojection filtration (BPF) algorithm is capable of reconstructing ROI images without truncation artifacts from truncated cone-beam data. We apply the BPF algorithm to reconstructing ROI images from truncated data of three different objects acquired by our circular cone-beam microCT system. Reconstructed images by use of the FDK and BPF algorithms from both truncated and nontruncated cone-beam data are compared. The results of the experimental studies demonstrate that, from certain truncated data, the BPF algorithm can reconstruct ROI images with quality comparable to that reconstructed from nontruncated data. In contrast, the FDK algorithm yields ROI images with truncation artifacts. Therefore, an implication of the studies is that, when truncated data are acquired with a configuration of a large geometric magnification, the BPF algorithm can be used for effective enhancement of the spatial resolution of a ROI image.« less

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

NASA Astrophysics Data System (ADS)

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

2013-08-01

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

TU-F-CAMPUS-I-05: Investigation of An EMCCD Detector with Variable Gain in a Micro-CT System

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

Krishnakumar, S Bysani; Ionita, C; Rudin, S

Purpose: To investigate the performance of a newly built Electron Multiplying Charged Coupled Device (EMCCD) based Micro-CT system, with variable detector gain, using a phantom containing contrast agent of different concentrations. Methods: We built a micro- CT system with an EMCCD having 8 microns pixels and on-chip variable gain. We tested the system using a phantom containing five tubes filled with different iodine contrast solutions (30% to 70%). First, we scanned the phantom using various x-ray exposures values at 40 kVp and constant detector gain. Next, for the same tube currents, the detector gain was increased to maintain the airmore » value of the projection image constant. A standard FDK algorithm was used to reconstruct the data. Performance was analyzed by comparing the signal-to-noise ratio (SNR) measurements for increased gain with those for the low constant gain at each exposure. Results: The high detector gain reconstructed data SNR was always greater than the low gain data SNR for all x-ray settings and for all iodine features. The largest increases were observed for low contrast features, 30% iodine concentration, where the SNR improvement approached 2. Conclusion: One of the first implementations of an EMCCD based micro- CT system was presented and used to image a phantom with various iodine solution concentrations. The analysis of the reconstructed volumes showed a significant improvement of the SNR especially for low contrast features. The unique on-chip gain feature is a substantial benefit allowing the use of the system at very low x-ray exposures per frame.Partial support: NIH grant R01EB002873 and Toshiba Medical Systems Corp. Partial support: NIH grant R01EB002873 and Toshiba Medical Systems Corp.« less

Status of the Micro-X Sounding Rocket X-Ray Spectrometer

NASA Technical Reports Server (NTRS)

Goldfinger, D. C.; Adams, J. S.; Baker, R.; Bandler, S. R.; Danowski, M. E.; Doriese, W. B.; Eckart, M. E.; Figueroa-Feliciano, E.; Hilton, G. C.; Hubbard, A. J. F.;

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

X-ray micro-CT and neutron CT as complementary imaging tools for non-destructive 3D imaging of rare silicified fossil plants

NASA Astrophysics Data System (ADS)

Karch, J.; Dudák, J.; Žemlička, J.; Vavřík, D.; Kumpová, I.; Kvaček, J.; Heřmanová, Z.; Šoltés, J.; Viererbl, L.; Morgano, M.; Kaestner, A.; Trtík, P.

2017-12-01

Computed tomography provides 3D information of inner structures of investigated objects. The obtained information is, however, strongly dependent on the used radiation type. It is known that as X-rays interact with electron cloud and neutrons with atomic nucleus, the obtained data often provide different contrast of sample structures. In this work we present a set of comparative radiographic and CT measurements of rare fossil plant samples using X-rays and thermal neutrons. The X-ray measurements were performed using large area photon counting detectors Timepix at IEAP CTU in Prague and Perkin Elmer flat-panel detector at Center of Excellence Telč. The neutron CT measurement was carried out at Paul Scherrer Institute using BOA beam-line. Furthermore, neutron radiography of fossil samples, provided by National Museum, were performed using a large-area Timepix detector with a neutron-sensitive converting 6LiF layer at Research Centre Rez, Czech Republic. The obtained results show different capabilities of both imaging approaches. While X-ray micro-CT provides very high resolution and enables visualization of fine cracks or small cavities in the samples neutron imaging provides high contrast of morphological structures of fossil plant samples, where X-ray imaging provides insufficient contrast.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD).

PubMed

Russ, M; Shankar, A; Jain, A; Setlur Nagesh, S V; Ionita, C N; Scott, C; Karim, K S; Bednarek, D R; Rudin, S

2016-02-27

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25 μ m pixel pitch, and 1000 μ m thick a-Se layer operating at 10V/ μ m bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

NASA Astrophysics Data System (ADS)

Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

2016-03-01

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-pre-whitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal- spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide break- through abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD)

PubMed Central

Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

2017-01-01

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices. PMID:28615795

Digitized neutron imaging with high spatial resolution at a low power research reactor: I. Analysis of detector performance

NASA Astrophysics Data System (ADS)

Zawisky, M.; Hameed, F.; Dyrnjaja, E.; Springer, J.

2008-03-01

Imaging techniques provide an indispensable tool for investigation of materials. Neutrons, due to their specific properties, offer a unique probe for many aspects of condensed matter. Neutron imaging techniques present a challenging experimental task, especially at a low power research reactor. The Atomic Institute with a 250 kW TRIGA MARK II reactor looks back at a long tradition in neutron imaging. Here we report on the advantages gained in a recent upgrade of the imaging instrument including the acquisition of a thin-plate scintillation detector, a single counting micro-channel plate detector, and an imaging plate detector in combination with a high resolution scanner. We analyze the strengths and limitations of each detector in the field of neutron radiography and tomography, and demonstrate that high resolution digitized imaging down to the 50 μm scale can be accomplished with weak beam intensities of 1.3×10 5 n/cm 2 s, if appropriate measures are taken for the inevitable extension of measurement times. In a separate paper we will present some promising first results from the fields of engineering and geology.

Velocity map imaging using an in-vacuum pixel detector.

PubMed

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan; Jungmann, Julia; Visschers, Jan; Vrakking, Marc J J

2009-10-01

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256 x 256 square pixels, 55 x 55 microm2) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 micros. Results of the first time application of the Medipix2 detector to VMI are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.

Live small-animal X-ray lung velocimetry and lung micro-tomography at the Australian Synchrotron Imaging and Medical Beamline.

PubMed

Murrie, Rhiannon P; Morgan, Kaye S; Maksimenko, Anton; Fouras, Andreas; Paganin, David M; Hall, Chris; Siu, Karen K W; Parsons, David W; Donnelley, Martin

2015-07-01

The high flux and coherence produced at long synchrotron beamlines makes them well suited to performing phase-contrast X-ray imaging of the airways and lungs of live small animals. Here, findings of the first live-animal imaging on the Imaging and Medical Beamline (IMBL) at the Australian Synchrotron are reported, demonstrating the feasibility of performing dynamic lung motion measurement and high-resolution micro-tomography. Live anaesthetized mice were imaged using 30 keV monochromatic X-rays at a range of sample-to-detector propagation distances. A frame rate of 100 frames s(-1) allowed lung motion to be determined using X-ray velocimetry. A separate group of humanely killed mice and rats were imaged by computed tomography at high resolution. Images were reconstructed and rendered to demonstrate the capacity for detailed, user-directed display of relevant respiratory anatomy. The ability to perform X-ray velocimetry on live mice at the IMBL was successfully demonstrated. High-quality renderings of the head and lungs visualized both large structures and fine details of the nasal and respiratory anatomy. The effect of sample-to-detector propagation distance on contrast and resolution was also investigated, demonstrating that soft tissue contrast increases, and resolution decreases, with increasing propagation distance. This new capability to perform live-animal imaging and high-resolution micro-tomography at the IMBL enhances the capability for investigation of respiratory diseases and the acceleration of treatment development in Australia.

A Novel Multi-Aperture Based Sun Sensor Based on a Fast Multi-Point MEANSHIFT (FMMS) Algorithm

PubMed Central

You, Zheng; Sun, Jian; Xing, Fei; Zhang, Gao-Fei

2011-01-01

With the current increased widespread interest in the development and applications of micro/nanosatellites, it was found that we needed to design a small high accuracy satellite attitude determination system, because the star trackers widely used in large satellites are large and heavy, and therefore not suitable for installation on micro/nanosatellites. A Sun sensor + magnetometer is proven to be a better alternative, but the conventional sun sensor has low accuracy, and cannot meet the requirements of the attitude determination systems of micro/nanosatellites, so the development of a small high accuracy sun sensor with high reliability is very significant. This paper presents a multi-aperture based sun sensor, which is composed of a micro-electro-mechanical system (MEMS) mask with 36 apertures and an active pixels sensor (APS) CMOS placed below the mask at a certain distance. A novel fast multi-point MEANSHIFT (FMMS) algorithm is proposed to improve the accuracy and reliability, the two key performance features, of an APS sun sensor. When the sunlight illuminates the sensor, a sun spot array image is formed on the APS detector. Then the sun angles can be derived by analyzing the aperture image location on the detector via the FMMS algorithm. With this system, the centroid accuracy of the sun image can reach 0.01 pixels, without increasing the weight and power consumption, even when some missing apertures and bad pixels appear on the detector due to aging of the devices and operation in a harsh space environment, while the pointing accuracy of the single-aperture sun sensor using the conventional correlation algorithm is only 0.05 pixels. PMID:22163770

X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

NASA Astrophysics Data System (ADS)

Dudak, J.; Karch, J.; Holcova, K.; Zemlicka, J.

2017-12-01

As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer.

In vivo small animal micro-CT using nanoparticle contrast agents

PubMed Central

Ashton, Jeffrey R.; West, Jennifer L.; Badea, Cristian T.

2015-01-01

Computed tomography (CT) is one of the most valuable modalities for in vivo imaging because it is fast, high-resolution, cost-effective, and non-invasive. Moreover, CT is heavily used not only in the clinic (for both diagnostics and treatment planning) but also in preclinical research as micro-CT. Although CT is inherently effective for lung and bone imaging, soft tissue imaging requires the use of contrast agents. For small animal micro-CT, nanoparticle contrast agents are used in order to avoid rapid renal clearance. A variety of nanoparticles have been used for micro-CT imaging, but the majority of research has focused on the use of iodine-containing nanoparticles and gold nanoparticles. Both nanoparticle types can act as highly effective blood pool contrast agents or can be targeted using a wide variety of targeting mechanisms. CT imaging can be further enhanced by adding spectral capabilities to separate multiple co-injected nanoparticles in vivo. Spectral CT, using both energy-integrating and energy-resolving detectors, has been used with multiple contrast agents to enable functional and molecular imaging. This review focuses on new developments for in vivo small animal micro-CT using novel nanoparticle probes applied in preclinical research. PMID:26581654

THCOBRA X-ray imaging detector operating in pure Kr

NASA Astrophysics Data System (ADS)

Carramate, L. F. N. D.; Silva, A. L. M.; Azevedo, C. D. R.; Fortes, I.; Monteiro, S. G.; Sousa, S.; Ribeiro, F. M.; De Francesco, S.; Covita, D. S.; Veloso, J. F. C. A.

2017-05-01

MicroPattern Gaseous Detectors (MPGD) have been explored for X-ray imaging, namely for photon counting imaging which allows the improvement of image quality and the collection of more information than the conventional commercial systems. A 2D-THCOBRA based detector was developed, studied and used to acquire X-ray transmission images. The 2D-THCOBRA structure used has an active area of 2.8 × 2.8 cm2 and allows obtaining the position and energy information of each single photon that interacts with the detector. It is filled with pure Kr at 1 bar operating in a sealed mode. Within this work the performance of the detector is evaluated in terms of charge gain, count rate, time stability, energy and spatial resolutions. The detector presents a charge gain of 2 × 104 and an energy resolution of 23% for 5.9 keV, showing gain stability along time for a count rate of about 1 × 105 Hz/mm2. It presents a spatial resolution of 600 μm (σ = 255 μm) and 500 μm (σ = 213 μm) for x and y directions, respectively, and, considering energy bins about 650 μm (σ = 277 μm) for approximately 16.5 keV. X-ray transmission images of some samples presented here show good prospects for X-ray imaging applications.

Radiation dose reduction in chest radiography using a flat-panel amorphous silicon detector.

PubMed

Hosch, W P; Fink, C; Radeleff, B; kampschulte a, A; Kauffmann, G W; Hansmann, J

2002-10-01

The aim of this study was to evaluate the image quality and the potential for radiation dose reduction with a digital flat-panel amorphous silicon detector radiography system. Using flat-panel technology, radiographs of an anthropomorphic thorax phantom were taken with a range of technical parameters (125kV, 200mA and 5, 4, 3.2, 2, 1, 0.5, and 0.25mAs) which were equivalent to a radiation dose of 332, 263, 209, 127, 58.7, 29, and 14 microGy, respectively. These images were compared to radiographs obtained by a conventional film-screen radiography system at 125kV, 200mA and 5mAs (equivalent to 252 microGy) which served as reference. Three observers evaluated independently the visibility of simulated rounded lesions and anatomical structures, comparing printed films from the flat-panel amorphous silicon detector and conventional x-ray system films. With flat-panel technology, the visibility of rounded lesions and normal anatomical structures at 5, 4, and 3.2mAs was superior compared to the conventional film-screen radiography system. (P< or =0.0001). At 2mAs, improvement was only marginal (P=0.19). At 1.0, 0.5 and 0.25mAs, the visibility of simulated rounded lesions was worse (P< or =0.004). Comparing fine lung parenchymal structures, the flat-panel amorphous silicon detector showed improvement for all exposure levels down to 2mAs and equality at 1mAs. Compared to a conventional x-ray film system, the flat-panel amorphous silicon detector demonstrated improved image quality and the possibility for a reduction of the radiation dose by 50% without loss in image quality.

A machine vision system for micro-EDM based on linux

NASA Astrophysics Data System (ADS)

Guo, Rui; Zhao, Wansheng; Li, Gang; Li, Zhiyong; Zhang, Yong

2006-11-01

Due to the high precision and good surface quality that it can give, Electrical Discharge Machining (EDM) is potentially an important process for the fabrication of micro-tools and micro-components. However, a number of issues remain unsolved before micro-EDM becomes a reliable process with repeatable results. To deal with the difficulties in micro electrodes on-line fabrication and tool wear compensation, a micro-EDM machine vision system is developed with a Charge Coupled Device (CCD) camera, with an optical resolution of 1.61μm and an overall magnification of 113~729. Based on the Linux operating system, an image capturing program is developed with the V4L2 API, and an image processing program is exploited by using OpenCV. The contour of micro electrodes can be extracted by means of the Canny edge detector. Through the system calibration, the micro electrodes diameter can be measured on-line. Experiments have been carried out to prove its performance, and the reasons of measurement error are also analyzed.

SU-F-T-68: Characterizes of Microdetectors in Electron Beam Dosimetry

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

Das, I; Andersen, A; Akino, Y

Purpose: Electron beam dosimetry requires high resolution data due to finite range that can be accomplished with small volume detectors. The small-field used in advance technologies in photon beam has created a market for microdetectors, however characteristics are significantly variable in photon beams and relatively unknown in electron beam that is investigated in this study. Methods: Among nearly 2 dozen microdetectors that have been investigated in small fields of photon beam, two popular detectors (microDiamond 60019 (PTW)) and W1 plastic scintillator detector (Standard Imaging)) that are tissue equivalent and have very small sensitive volume are selected. Electron beams from Varianmore » linear accelerators were used to investigate dose linearity dose rate dependence, energy dependence, depth dose and profiles in a reference condition in a water phantom. For W1 that has its own Supermax electrometer point by point measurements were performed. For microDiamond, a PTW-scanning tank was used for both scanning and point dose measurements. Results: W1 detector showed excellent dose linearity (r{sup 2} =1.0) from 5–500 MU either with variation of dose rate or beam energy. Similar findings were also observed for microdiamond with r{sup 2}=1.0. Percent variations in dose/MU for W1 and microDiamond were 0.2–1.1% and 0.4–1.2%, respectively among dose rate and beam energy. This variation was random for microDiamond, whereas it decreased with beam energy and dose rate for W1. The depth dose and profiles were within ±1 mm for both detectors. Both detectors did not show any energy dependence in electron beams. Conclusion: Both microDiamond and W1 detectors provided superior characteristics of beam parameters in electron beam including dose, dose rate linearity and energy independence. Both can be used in electron beam except W1 require point by point measurements and microdiamond requires 1500 MU for initial quenching.« less

Design considerations for a new, high resolution Micro-Angiographic Fluoroscope based on a CMOS sensor (MAF-CMOS).

PubMed

Loughran, Brendan; Swetadri Vasan, S N; Singh, Vivek; Ionita, Ciprian N; Jain, Amit; Bednarek, Daniel R; Titus, Albert; Rudin, Stephen

2013-03-06

The detectors that are used for endovascular image-guided interventions (EIGI), particularly for neurovascular interventions, do not provide clinicians with adequate visualization to ensure the best possible treatment outcomes. Developing an improved x-ray imaging detector requires the determination of estimated clinical x-ray entrance exposures to the detector. The range of exposures to the detector in clinical studies was found for the three modes of operation: fluoroscopic mode, high frame-rate digital angiographic mode (HD fluoroscopic mode), and DSA mode. Using these estimated detector exposure ranges and available CMOS detector technical specifications, design requirements were developed to pursue a quantum limited, high resolution, dynamic x-ray detector based on a CMOS sensor with 50 μm pixel size. For the proposed MAF-CMOS, the estimated charge collected within the full exposure range was found to be within the estimated full well capacity of the pixels. Expected instrumentation noise for the proposed detector was estimated to be 50-1,300 electrons. Adding a gain stage such as a light image intensifier would minimize the effect of the estimated instrumentation noise on total image noise but may not be necessary to ensure quantum limited detector operation at low exposure levels. A recursive temporal filter may decrease the effective total noise by 2 to 3 times, allowing for the improved signal to noise ratios at the lowest estimated exposures despite consequent loss in temporal resolution. This work can serve as a guide for further development of dynamic x-ray imaging prototypes or improvements for existing dynamic x-ray imaging systems.

Medipix-based Spectral Micro-CT.

PubMed

Yu, Hengyong; Xu, Qiong; He, Peng; Bennett, James; Amir, Raja; Dobbs, Bruce; Mou, Xuanqin; Wei, Biao; Butler, Anthony; Butler, Phillip; Wang, Ge

2012-12-01

Since Hounsfield's Nobel Prize winning breakthrough decades ago, X-ray CT has been widely applied in the clinical and preclinical applications - producing a huge number of tomographic gray-scale images. However, these images are often insufficient to distinguish crucial differences needed for diagnosis. They have poor soft tissue contrast due to inherent photon-count issues, involving high radiation dose. By physics, the X-ray spectrum is polychromatic, and it is now feasible to obtain multi-energy, spectral, or true-color, CT images. Such spectral images promise powerful new diagnostic information. The emerging Medipix technology promises energy-sensitive, high-resolution, accurate and rapid X-ray detection. In this paper, we will review the recent progress of Medipix-based spectral micro-CT with the emphasis on the results obtained by our team. It includes the state- of-the-art Medipix detector, the system and method of a commercial MARS (Medipix All Resolution System) spectral micro-CT, and the design and color diffusion of a hybrid spectral micro-CT.

The Detector and Readout Systems of the Micro-X High Resolution Microcalorimeter X-Ray Imaging Rocket

NASA Astrophysics Data System (ADS)

Wikus, P.; Doriese, W. B.; Eckart, M. E.; Adams, J. S.; Bandler, S. R.; Brekosky, R. P.; Chervenak, J. A.; Ewin, A. J.; Figueroa-Feliciano, E.; Finkbeiner, F. M.; Galeazzi, M.; Hilton, G.; Irwin, K. D.; Kelley, R. L.; Kilbourne, C. A.; Leman, S. W.; McCammon, D.; Porter, F. S.; Reintsema, C. D.; Rutherford, J. M.; Trowbridge, S. N.

2009-12-01

The Micro-X sounding rocket experiment will deploy an imaging transition-edge-sensor (TES) microcalorimeter spectrometer to observe astrophysical sources in the 0.2-3.0 keV band. The instrument has been designed at a systems level, and the first items of flight hardware are presently being built. In the first flight, planned for January 2011, the spectrometer will observe a recently discovered Silicon knot in the Puppis-A supernova remnant. Here we describe the design of the Micro-X science instrument, focusing on the instrument's detector and detector assembly. The current design of the 2-dimensional spectrometer array contains 128 close-packed pixels with a pitch of 600 μm. The conically approximated Wolter-1 mirror will map each of these pixels to a 0.95 arcmin region on the sky; the field of view will be 11.4 arcmin. Targeted energy resolution of the TESs is about 2 eV over the full observing band. A SQUID time-division multiplexer (TDM) will read out the array. The detector time constants will be engineered to approximately 2 ms to match the TDM, which samples each pixel at 32.6 kHz, limited only by the telemetry system of the rocket. The detector array and two SQUID stages of the TDM readout system are accommodated in a lightweight Mg enclosure, which is mounted to the 50 mK stage of an adiabatic demagnetization refrigerator. A third SQUID amplification stage is located on the 1.6 K liquid He stage of the cryostat. An on-board 55-Fe source will fluoresce a Ca target, providing 3.69 and 4.01 keV calibration lines that will not interfere with the scientifically interesting energy band.

X-ray fluorescence imaging system for fast mapping of pigment distributions in cultural heritage paintings

NASA Astrophysics Data System (ADS)

Zielińska, A.; Dąbrowski, W.; Fiutowski, T.; Mindur, B.; Wiącek, P.; Wróbel, P.

2013-10-01

Conventional X-ray fluorescence imaging technique uses a focused X-ray beam to scan through the sample and an X-ray detector with high energy resolution but no spatial resolution. The spatial resolution of the image is then determined by the size of the exciting beam, which can be obtained either from a synchrotron source or from an X-ray tube with a micro-capillary lens. Such a technique based on a pixel-by-pixel measurement is very slow and not suitable for imaging large area samples. The goal of this work is to develop a system capable of simultaneous imaging of large area samples by using a wide field uniform excitation X-ray beam and a position sensitive and energy dispersive detector. The development is driven by possible application of such a system to imaging of distributions of hidden pigments containing specific elements in cultural heritage paintings, which is of great interest for the cultural heritage research. The fluorescence radiation from the area of 10 × 10 cm2 is projected through a pinhole camera on the Gas Electron Multiplier detector of the same area. The detector is equipped with two sets of orthogonal readout strips. The strips are read out by the GEMROC Application Specific Integrated Circuits (ASIC)s, which deliver time and amplitude information for each hit. This ASIC architecture combined with a Field Programmable Gate Array (FPGA) based readout system allows us to reconstruct the position and the total energy of each detected photon for high count rates up to 5 × 106 cps. Energy resolution better than 20% FWHM for the 5.9 keV line and spatial resolution of 1 mm FWHM have been achieved for the prototype system. Although the energy resolution of the Gas Electron Multiplier (GEM) detector is, by principle, not competitive with that of specialised high energy resolution semiconductor detectors, it is sufficient for a number of applications. Compared to conventional micro-XRF techniques the developed system allows shortening of the measurement time by 2-3 orders of magnitude.

Technological aspects of GEM detector design and assembling for soft x-ray application

NASA Astrophysics Data System (ADS)

Kowalska-Strzeciwilk, E.; Chernyshova, M.

2016-09-01

Various types of Micro Pattern Gas Detectors (MPGDs) found applications as tracking detectors in high energy particle physics experiments and as well as imaging detectors, especially for soft X-rays. These detectors offer several advantages like high count rate capability, good spatial and energy resolution, low cost and possibility of constructing large area detectors with very small dead area. Construction, like the triple Gas Electron Multiplier (GEM) detector has become a standard detector, which is widely used for different imaging applications. Some examples of such applications are: monitoring the impurity in plasma, imaging system for mapping of some parameters like pigment distributions using X-ray fluorescence technique[1], proton range radiography system for quality assurance in hadron therapy. Measuring of the Soft X-Ray (SXR) radiation of magnetic fusion plasma is a standard way of accessing valuable information, for example, about particle transport and MHD. The paper is focused on the design of GEM based soft Xray radiation detecting system which is under development. It is dedicated to study soft X-ray emission of plasma radiation with focus on tungsten emission lines energy region. The paper presents the designing, construction and assembling of a prototype of two triple-GEM detectors for soft-X ray application on the WEST device.

Evaluation of a photon counting Medipix3RX CZT spectral x-ray detector

PubMed Central

Jorgensen, Steven M.; Vercnocke, Andrew J.; Rundle, David S.; Butler, Philip H.; McCollough, Cynthia H.; Ritman, Erik L.

2016-01-01

We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels. Pixel response curves were created by imaging a range of x-ray intensities by varying x-ray tube current and by varying the exposure time with fixed x-ray current. Photon energy-related assessments were made by flooding the detector with the tin foil filtered emission of an I-125 radioisotope brachytherapy seed and sweeping the energy threshold of each of the four charge-summed counters of each pixel in 1 keV steps. Long term stability assessments were made by repeating exposures over the course of one hour. The high properly-functioning pixel yield (99%), long term stability (linear regression of whole-chip response over one hour of acquisitions: y = −0.0038x + 2284; standard deviation: 3.7 counts) and energy resolution (2.5 keV FWHM (single pixel), 3.7 keV FWHM across the full image) make this device suitable for spectral micro-CT. The charge summing performance effectively reduced the measurement corruption caused by charge sharing which, when unaccounted for, shifts the photon energy assignment to lower energies, degrading both count and energy accuracy. Effective charge summing greatly improves the potential for calibrated, energy-specific material decomposition and K edge difference imaging approaches. PMID:27795606

Evaluation of a photon counting Medipix3RX CZT spectral x-ray detector.

PubMed

Jorgensen, Steven M; Vercnocke, Andrew J; Rundle, David S; Butler, Philip H; McCollough, Cynthia H; Ritman, Erik L

2016-08-28

We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels. Pixel response curves were created by imaging a range of x-ray intensities by varying x-ray tube current and by varying the exposure time with fixed x-ray current. Photon energy-related assessments were made by flooding the detector with the tin foil filtered emission of an I-125 radioisotope brachytherapy seed and sweeping the energy threshold of each of the four charge-summed counters of each pixel in 1 keV steps. Long term stability assessments were made by repeating exposures over the course of one hour. The high properly-functioning pixel yield (99%), long term stability (linear regression of whole-chip response over one hour of acquisitions: y = -0.0038x + 2284; standard deviation: 3.7 counts) and energy resolution (2.5 keV FWHM (single pixel), 3.7 keV FWHM across the full image) make this device suitable for spectral micro-CT. The charge summing performance effectively reduced the measurement corruption caused by charge sharing which, when unaccounted for, shifts the photon energy assignment to lower energies, degrading both count and energy accuracy. Effective charge summing greatly improves the potential for calibrated, energy-specific material decomposition and K edge difference imaging approaches.

Design and performance evaluation of a high resolution IRI-microPET preclinical scanner

NASA Astrophysics Data System (ADS)

Islami rad, S. Z.; Peyvandi, R. Gholipour; lehdarboni, M. Askari; Ghafari, A. A.

2015-05-01

PET for small animal, IRI-microPET, was designed and built at the NSTRI. The scanner is made of four detectors positioned on a rotating gantry at a distance 50 mm from the center. Each detector consists of a 10×10 crystal matrix of 2×2×10 mm3 directly coupled to a PS-PMT. A position encoding circuit for specific PS-PMT has been designed, built and tested with a PD-MFS-2MS/s-8/14 data acquisition board. After implementing reconstruction algorithms (FBP, MLEM and SART) on sinograms, images quality and system performance were evaluated by energy resolution, timing resolution, spatial resolution, scatter fraction, sensitivity, RMS contrast and SNR parameters. The energy spectra were obtained for the crystals with an energy window of 300-700 keV. The energy resolution in 511 keV averaged over all modules, detectors, and crystals, was 23.5%. A timing resolution of 2.4 ns FWHM obtained by coincidence timing spectrum was measured with crystal LYSO. The radial and tangential resolutions for 18F (1.15-mm inner diameter) at the center of the field of view were 1.81 mm and 1.90 mm, respectively. At a radial offset of 5 mm, the FWHM values were 1.96 and 2.06 mm. The system scatter fraction was 7.1% for the mouse phantom. The sensitivity was measured for different energy windows, leading to a sensitivity of 1.74% at the center of FOV. Also, images quality was evaluated by RMS contrast and SNR factors, and the results show that the reconstructed images by MLEM algorithm have the best RMS contrast, and SNR. The IRI-microPET presents high image resolution, low scatter fraction values and improved SNR for animal studies.

Integrated ultrasonic particle positioning and low excitation light fluorescence imaging

NASA Astrophysics Data System (ADS)

Bernassau, A. L.; Al-Rawhani, M.; Beeley, J.; Cumming, D. R. S.

2013-12-01

A compact hybrid system has been developed to position and detect fluorescent micro-particles by combining a Single Photon Avalanche Diode (SPAD) imager with an acoustic manipulator. The detector comprises a SPAD array, light-emitting diode (LED), lenses, and optical filters. The acoustic device is formed of multiple transducers surrounding an octagonal cavity. By stimulating pairs of transducers simultaneously, an acoustic landscape is created causing fluorescent micro-particles to agglomerate into lines. The fluorescent pattern is excited by a low power LED and detected by the SPAD imager. Our technique combines particle manipulation and visualization in a compact, low power, portable setup.

Evaluation of sample holders designed for long-lasting X-ray micro-tomographic scans of ex-vivo soft tissue samples

NASA Astrophysics Data System (ADS)

Dudak, J.; Zemlicka, J.; Krejci, F.; Karch, J.; Patzelt, M.; Zach, P.; Sykora, V.; Mrzilkova, J.

2016-03-01

X-ray microradiography and microtomography are imaging techniques with increasing applicability in the field of biomedical and preclinical research. Application of hybrid pixel detector Timepix enables to obtain very high contrast of low attenuating materials such as soft biological tissue. However X-ray imaging of ex-vivo soft tissue samples is a difficult task due to its structural instability. Ex-vivo biological tissue is prone to fast drying-out which is connected with undesired changes of sample size and shape producing later on artefacts within the tomographic reconstruction. In this work we present the optimization of our Timepix equipped micro-CT system aiming to maintain soft tissue sample in stable condition. Thanks to the suggested approach higher contrast of tomographic reconstructions can be achieved while also large samples that require detector scanning can be easily measured.

Reduced As Components in Highly Oxidized Environments: Evidence from Full Spectral XANES Imaging using the Maia Massively Parallel Detector

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

Etschmann, B.; Ryan, C; Brugger, J

2010-01-01

Synchrotron X-ray fluorescence (SXRF) and X-ray absorption spectroscopy (XAS) have become standard tools to measure element concentration, distribution at micrometer- to nanometer-scale, and speciation (e.g., nature of host phase; oxidation state) in inhomogeneous geomaterials. The new Maia X-ray detector system provides a quantum leap for the method in terms of data acquisition rate. It is now possible to rapidly collect fully quantitative maps of the distribution of major and trace elements at micrometer spatial resolution over areas as large as 1 x 5 cm{sup 2}. Fast data acquisition rates also open the way to X-ray absorption near-edge structure (XANES) imaging,more » in which spectroscopic information is available at each pixel in the map. These capabilities are critical for studying inhomogeneous Earth materials. Using a 96-element prototype Maia detector, we imaged thin sections of an oxidized pisolitic regolith (2 x 4.5 mm{sup 2} at 2.5 x 2.5 {micro}m{sup 2} pixel size) and a metamorphosed, sedimentary exhalative Mn-Fe ore (3.3 x 4 mm{sup 2} at 1.25 x 5 {micro}m{sup 2}). In both cases, As K-edge XANES imaging reveals localized occurrence of reduced As in parts of these oxidized samples, which would have been difficult to recognize using traditional approaches.« less

Implementation of material decomposition using an EMCCD and CMOS-based micro-CT system.

PubMed

Podgorsak, Alexander R; Nagesh, Sv Setlur; Bednarek, Daniel R; Rudin, Stephen; Ionita, Ciprian N

2017-02-11

This project assessed the effectiveness of using two different detectors to obtain dual-energy (DE) micro-CT data for the carrying out of material decomposition. A micro-CT coupled to either a complementary metal-oxide semiconductor (CMOS) or an electron multiplying CCD (EMCCD) detector was used to acquire image data of a 3D-printed phantom with channels filled with different materials. At any instance, materials such as iohexol contrast agent, water, and platinum were selected to make up the scanned object. DE micro-CT data was acquired, and slices of the scanned object were differentiated by material makeup. The success of the decomposition was assessed quantitatively through the computation of percentage normalized root-mean-square error (%NRMSE). Our results indicate a successful decomposition of iohexol for both detectors (%NRMSE values of 1.8 for EMCCD, 2.4 for CMOS), as well as platinum (%NRMSE value of 4.7). The CMOS detector performed material decomposition on air and water on average with 7 times more %NRMSE, possibly due to the decreased sensitivity of the CMOS system. Material decomposition showed the potential to differentiate between materials such as the iohexol and platinum, perhaps opening the door for its use in the neurovascular anatomical region. Work supported by Toshiba America Medical Systems, and partially supported by NIH grant 2R01EB002873.

Implementation of material decomposition using an EMCCD and CMOS-based micro-CT system

NASA Astrophysics Data System (ADS)

Podgorsak, Alexander R.; Nagesh, S. V. Setlur; Bednarek, Daniel R.; Rudin, Stephen; Ionita, Ciprian N.

2017-03-01

This project assessed the effectiveness of using two different detectors to obtain dual-energy (DE) micro-CT data for the carrying out of material decomposition. A micro-CT coupled to either a complementary metal-oxide semiconductor (CMOS) or an electron multiplying CCD (EMCCD) detector was used to acquire image data of a 3D-printed phantom with channels filled with different materials. At any instance, materials such as iohexol contrast agent, water, and platinum were selected to make up the scanned object. DE micro-CT data was acquired, and slices of the scanned object were differentiated by material makeup. The success of the decomposition was assessed quantitatively through the computation of percentage normalized root-mean-square error (%NRMSE). Our results indicate a successful decomposition of iohexol for both detectors (%NRMSE values of 1.8 for EMCCD, 2.4 for CMOS), as well as platinum (%NRMSE value of 4.7). The CMOS detector performed material decomposition on air and water on average with 7 times more %NRMSE, possibly due to the decreased sensitivity of the CMOS system. Material decomposition showed the potential to differentiate between materials such as the iohexol and platinum, perhaps opening the door for its use in the neurovascular anatomical region. Work supported by Toshiba America Medical Systems, and partially supported by NIH grant 2R01EB002873.

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

NASA Astrophysics Data System (ADS)

Fast, J.; Belle II Barrel Particle Identification Group

2017-12-01

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

Dual-energy micro-CT with a dual-layer, dual-color, single-crystal scintillator.

PubMed

Maier, Daniel Simon; Schock, Jonathan; Pfeiffer, Franz

2017-03-20

A wide range of X-ray imaging applications demand micrometer spatial resolution. In material science and biology especially, there is a great interest in material determination and material separation methods. Here we present a new detector design that allows the recording of a low- and a high-energy radiography image simultaneously with micrometer spatial resolution. The detector system is composed of a layered scintillator stack, two CCDs and an optical system to image the scintillator responses onto the CCDs. We used the detector system with a standard laboratory microfocus X-ray tube to prove the working principle of the system and derive important design characteristics. With the recorded and registered dual-energy data set, the material separation and determination could be shown at an X-ray tube peak energy of up to 160 keV with a spatial resolution of 12 μm. The detector design shows a great potential for further development and a wide range of possible applications.

X-ray Polarimetry with a Micro-Pattern Gas Detector

NASA Technical Reports Server (NTRS)

Hill, Joe

2005-01-01

Topics covered include: Science drivers for X-ray polarimetry; Previous X-ray polarimetry designs; The photoelectric effect and imaging tracks; Micro-pattern gas polarimeter design concept. Further work includes: Verify results against simulator; Optimize pressure and characterize different gases for a given energy band; Optimize voltages for resolution and sensitivity; Test meshes with 80 micron pitch; Characterize ASIC operation; and Quantify quantum efficiency for optimum polarization sensitivity.

Vibration Isolation Design for the Micro-X Rocket Payload

NASA Technical Reports Server (NTRS)

Heine, S. N. T.; Figueroa-Feliciano, E.; Rutherford, J. M.; Wikus, P.; Oakley, P.; Porter, Frederick S.; McCammon, D.

2014-01-01

Micro-X is a NASA-funded, sounding rocket-borne X-ray imaging spectrometer that will allow high precision measurements of velocity structure, ionization state and elemental composition of extended astrophysical systems. One of the biggest challenges in payload design is to maintain the temperature of the detectors during launch. There are several vibration damping stages to prevent energy transmission from the rocket skin to the detector stage, which causes heating during launch. Each stage should be more rigid than the outer stages to achieve vibrational isolation. We describe a major design effort to tune the resonance frequencies of these vibration isolation stages to reduce heating problems prior to the projected launch in the summer of 2014.

Radiation imaging with optically read out GEM-based detectors

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

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

Manohar, N; Cho, S; Reynoso, F

Purpose: To make benchtop x-ray fluorescence computed tomography (XFCT) practical for routine preclinical imaging tasks with gold nanoparticles (GNPs) by deploying, integrating, and characterizing a dedicated high-performance x-ray source and addition of simultaneous micro-CT functionality. Methods: Considerable research effort is currently under way to develop a polychromatic benchtop cone-beam XFCT system capable of imaging GNPs by stimulation and detection of gold K-shell x-ray fluorescence (XRF) photons. Recently, an ad hoc high-power x-ray source was incorporated and used to image the biodistribution of GNPs within a mouse, postmortem. In the current work, a dedicated x-ray source system featuring a liquid-cooled tungsten-targetmore » x-ray tube (max 160 kVp, ∼3 kW power) was deployed. The source was operated at 125 kVp, 24 mA. The tube’s compact dimensions allowed greater flexibility for optimizing both the irradiation and detection geometries. Incident x-rays were shaped by a conical collimator and filtered by 2 mm of tin. A compact “OEM” cadmium-telluride x-ray detector was implemented for detecting XRF/scatter spectra. Additionally, a flat panel detector was installed to allow simultaneous transmission CT imaging. The performance of the system was characterized by determining the detection limit (10-second acquisition time) for inserts filled with water/GNPs at various concentrations (0 and 0.010–1.0 wt%) and embedded in a small-animal-sized phantom. The phantom was loaded with 0.5, 0.3, and 0.1 wt% inserts and imaged using XFCT and simultaneous micro-CT. Results: An unprecedented detection limit of 0.030 wt% was experimentally demonstrated, with a 33% reduction in acquisition time. The reconstructed XFCT image accurately localized the imaging inserts. Micro-CT imaging did not provide enough contrast to distinguish imaging inserts from the phantom under the current conditions. Conclusion: The system is immediately capable of in vivo preclinical XFCT imaging with GNPs. Micro-CT imaging will require optimization of irradiation parameters to improve contrast. Supported by NIH/NCI grant R01CA155446; This investigation was supported by NIH/NCI grant R01CA155446.« less

A quality assurance phantom for the performance evaluation of volumetric micro-CT systems

NASA Astrophysics Data System (ADS)

Du, Louise Y.; Umoh, Joseph; Nikolov, Hristo N.; Pollmann, Steven I.; Lee, Ting-Yim; Holdsworth, David W.

2007-12-01

Small-animal imaging has recently become an area of increased interest because more human diseases can be modeled in transgenic and knockout rodents. As a result, micro-computed tomography (micro-CT) systems are becoming more common in research laboratories, due to their ability to achieve spatial resolution as high as 10 µm, giving highly detailed anatomical information. Most recently, a volumetric cone-beam micro-CT system using a flat-panel detector (eXplore Ultra, GE Healthcare, London, ON) has been developed that combines the high resolution of micro-CT and the fast scanning speed of clinical CT, so that dynamic perfusion imaging can be performed in mice and rats, providing functional physiological information in addition to anatomical information. This and other commercially available micro-CT systems all promise to deliver precise and accurate high-resolution measurements in small animals. However, no comprehensive quality assurance phantom has been developed to evaluate the performance of these micro-CT systems on a routine basis. We have designed and fabricated a single comprehensive device for the purpose of performance evaluation of micro-CT systems. This quality assurance phantom was applied to assess multiple image-quality parameters of a current flat-panel cone-beam micro-CT system accurately and quantitatively, in terms of spatial resolution, geometric accuracy, CT number accuracy, linearity, noise and image uniformity. Our investigations show that 3D images can be obtained with a limiting spatial resolution of 2.5 mm-1 and noise of ±35 HU, using an acquisition interval of 8 s at an entrance dose of 6.4 cGy.

A Concept for a High-Energy Gamma-ray Polarimeter

NASA Technical Reports Server (NTRS)

Bloser, P. F.; Hunter, S. D.; Depaola, G. O.; Longo, F.

2003-01-01

We present a concept for an imaging gamma-ray polarimeter operating from approx. 50 MeV to approx. 1 GeV. Such an instrument would be valuable for the study of high-energy pulsars, active galactic nuclei, supernova remnants, and gamma-ray bursts. The concept makes use of pixelized gas micro-well detectors, under development at Goddard Space Flight Center, to record the electron-positron tracks from pair-production events in a large gas volume. Pixelized micro-well detectors have the potential to form large-volume 3-D track imagers with approx. 100 micron (rms) position resolution at moderate cost. The combination of high spatial resolution and a continuous low-density gas medium permits many thousands of measurements per radiation length, allowing the particle tracks to be imaged accurately before multiple scattering masks their original directions. The polarization of the incoming radiation may then be determined from the azimuthal distribution of the electron-positron pairs. We have performed Geant4 simulations of these processes to estimate the polarization sensitivity as a function of instrument parameters and event selection criteria.

Clinical radiation therapy measurements with a new commercial synthetic single crystal diamond detector

PubMed Central

Crilly, Richard

2014-01-01

A commercial version of a synthetic single crystal diamond detector (SCDD) in a Schottky diode configuration was recently released as the new type 60019 microDiamond detector (PTW‐Freiburg, Germany). In this study we investigate the dosimetric properties of this detector to independently confirm that findings from the developing group of the SCDDs still hold true for the commercial version of the SCDDs. We further explore if the use of the microDiamond detector can be expanded to high‐energy photon beams of up to 15 MV and to large field measurements. Measurements were performed with an Elekta Synergy linear accelerator delivering 6, 10, and 15 MV X‐rays, as well as 6, 9, 12, 15, and 20 MeV electron beams. The dependence of the microdiamond detector response on absorbed dose after connecting the detector was investigated. Furthermore, the dark current of the diamond detector was observed after irradiation. Results are compared to similar results from measurements with a diamond detector type 60003. Energy dependency was investigated, as well. Photon depth‐dose curves were measured for field sizes 3×3,10×10, and 30×30cm2. PDDs were measured with the Semiflex type 31010 detector, microLion type 31018 detector, P Diode type 60016, SRS Diode type 60018, and the microDiamond type 60019 detector (all PTW‐Freiburg). Photon profiles were measured at a depth of 10 cm. Electron depth‐dose curves normalized to the dose maximum were measured with the 14×14cm2 electron cone. PDDs were measured with a Markus chamber type 23343, an E Diode type 60017 and the microDiamond type 60019 detector (all PTW‐Freiburg). Profiles were measured with the E Diode and microDiamond at half of D90,D90,D70, and D50 depths and for electron cone sizes of 6×6cm2, 14×14cm2, and 20×20cm2. Within a tolerance of 0.5% detector response of the investigated detector was stable without any preirradiation. After preirradition with approximately 250 cGy the detector response was stable within 0.1%. A dark current after irradiation was not observed. The microDiamond detector shows no energy dependence in high energy photon or electron dosimetry. Electron PDD measurements with the E Diode and microDiamond are in good agreement. However, compared to E Diode measurements, dose values in the bremsstrahlungs region are about 0.5% lower when measured with the microDiamond detector. Markus detector measurements agree with E Diode measurements in the bremsstrahlungs region. For depths larger than dmax, depth‐dose curves of photon beams measured with the microDiamond detector are in close agreement to those measured with the microLion detector for small fields and with those measured with a Semiflex 0.125 cc ionization chamber for large fields. Differences are in the range of 0.25% and less. For profile measurements, microDiamond detector measurements agree well with microLion and P Diode measurements in the high‐dose region of the profile and the penumbra region. For areas outside the open field, P Diode measurements are about 0.5%–1.0% higher than microDiamond and microLion measurements. Thus it becomes evident that the investigated diamond detector (type 60019) is suitable for a wide range of applications in high‐energy photon and electron dosimetry and is interesting for relative, as well as absolute, dosimetry. PACS numbers: 00.06, 80.87 PMID:25493512

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

Loughran, B; Singh, V; Jain, A

Purpose: Although generalized linear system analytic metrics such as GMTF and GDQE can evaluate performance of the whole imaging system including detector, scatter and focal-spot, a simplified task-specific measured metric may help to better compare detector systems. Methods: Low quantum-noise images of a neuro-vascular stent with a modified ANSI head phantom were obtained from the average of many exposures taken with the high-resolution Micro-Angiographic Fluoroscope (MAF) and with a Flat Panel Detector (FPD). The square of the Fourier Transform of each averaged image, equivalent to the measured product of the system GMTF and the object function in spatial-frequency space, wasmore » then divided by the normalized noise power spectra (NNPS) for each respective system to obtain a task-specific generalized signal-to-noise ratio. A generalized measured relative object detectability (GM-ROD) was obtained by taking the ratio of the integral of the resulting expressions for each detector system to give an overall metric that enables a realistic systems comparison for the given detection task. Results: The GM-ROD provides comparison of relative performance of detector systems from actual measurements of the object function as imaged by those detector systems. This metric includes noise correlations and spatial frequencies relevant to the specific object. Additionally, the integration bounds for the GM-ROD can be selected to emphasis the higher frequency band of each detector if high-resolution image details are to be evaluated. Examples of this new metric are discussed with a comparison of the MAF to the FPD for neuro-vascular interventional imaging. Conclusion: The GM-ROD is a new direct-measured task-specific metric that can provide clinically relevant comparison of the relative performance of imaging systems. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.« less

Micro-CT images reconstruction and 3D visualization for small animal studying

NASA Astrophysics Data System (ADS)

Gong, Hui; Liu, Qian; Zhong, Aijun; Ju, Shan; Fang, Quan; Fang, Zheng

2005-01-01

A small-animal x-ray micro computed tomography (micro-CT) system has been constructed to screen laboratory small animals and organs. The micro-CT system consists of dual fiber-optic taper-coupled CCD detectors with a field-of-view of 25x50 mm2, a microfocus x-ray source, a rotational subject holder. For accurate localization of rotation center, coincidence between the axis of rotation and centre of image was studied by calibration with a polymethylmethacrylate cylinder. Feldkamp"s filtered back-projection cone-beam algorithm is adopted for three-dimensional reconstruction on account of the effective corn-beam angle is 5.67° of the micro-CT system. 200x1024x1024 matrix data of micro-CT is obtained with the magnification of 1.77 and pixel size of 31x31μm2. In our reconstruction software, output image size of micro-CT slices data, magnification factor and rotation sample degree can be modified in the condition of different computational efficiency and reconstruction region. The reconstructed image matrix data is processed and visualization by Visualization Toolkit (VTK). Data parallelism of VTK is performed in surface rendering of reconstructed data in order to improve computing speed. Computing time of processing a 512x512x512 matrix datasets is about 1/20 compared with serial program when 30 CPU is used. The voxel size is 54x54x108 μm3. The reconstruction and 3-D visualization images of laboratory rat ear are presented.

Theoretical performance analysis for CMOS based high resolution detectors.

PubMed

Jain, Amit; Bednarek, Daniel R; Rudin, Stephen

2013-03-06

High resolution imaging capabilities are essential for accurately guiding successful endovascular interventional procedures. Present x-ray imaging detectors are not always adequate due to their inherent limitations. The newly-developed high-resolution micro-angiographic fluoroscope (MAF-CCD) detector has demonstrated excellent clinical image quality; however, further improvement in performance and physical design may be possible using CMOS sensors. We have thus calculated the theoretical performance of two proposed CMOS detectors which may be used as a successor to the MAF. The proposed detectors have a 300 μm thick HL-type CsI phosphor, a 50 μm-pixel CMOS sensor with and without a variable gain light image intensifier (LII), and are designated MAF-CMOS-LII and MAF-CMOS, respectively. For the performance evaluation, linear cascade modeling was used. The detector imaging chains were divided into individual stages characterized by one of the basic processes (quantum gain, binomial selection, stochastic and deterministic blurring, additive noise). Ranges of readout noise and exposure were used to calculate the detectors' MTF and DQE. The MAF-CMOS showed slightly better MTF than the MAF-CMOS-LII, but the MAF-CMOS-LII showed far better DQE, especially for lower exposures. The proposed detectors can have improved MTF and DQE compared with the present high resolution MAF detector. The performance of the MAF-CMOS is excellent for the angiography exposure range; however it is limited at fluoroscopic levels due to additive instrumentation noise. The MAF-CMOS-LII, having the advantage of the variable LII gain, can overcome the noise limitation and hence may perform exceptionally for the full range of required exposures; however, it is more complex and hence more expensive.

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT-CT scanners

PubMed Central

DiFilippo, Frank P.

2008-01-01

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners. PMID:18635899

Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT CT scanners

NASA Astrophysics Data System (ADS)

Di Filippo, Frank P.

2008-08-01

A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high-resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners.

A synchrotron radiation microtomography system for the analysis of trabecular bone samples.

PubMed

Salomé, M; Peyrin, F; Cloetens, P; Odet, C; Laval-Jeantet, A M; Baruchel, J; Spanne, P

1999-10-01

X-ray computed microtomography is particularly well suited for studying trabecular bone architecture, which requires three-dimensional (3-D) images with high spatial resolution. For this purpose, we describe a three-dimensional computed microtomography (microCT) system using synchrotron radiation, developed at ESRF. Since synchrotron radiation provides a monochromatic and high photon flux x-ray beam, it allows high resolution and a high signal-to-noise ratio imaging. The principle of the system is based on truly three-dimensional parallel tomographic acquisition. It uses a two-dimensional (2-D) CCD-based detector to record 2-D radiographs of the transmitted beam through the sample under different angles of view. The 3-D tomographic reconstruction, performed by an exact 3-D filtered backprojection algorithm, yields 3-D images with cubic voxels. The spatial resolution of the detector was experimentally measured. For the application to bone investigation, the voxel size was set to 6.65 microm, and the experimental spatial resolution was found to be 11 microm. The reconstructed linear attenuation coefficient was calibrated from hydroxyapatite phantoms. Image processing tools are being developed to extract structural parameters quantifying trabecular bone architecture from the 3-D microCT images. First results on human trabecular bone samples are presented.

[The optimizing design and experiment for a MOEMS micro-mirror spectrometer].

PubMed

Mo, Xiang-xia; Wen, Zhi-yu; Zhang, Zhi-hai; Guo, Yuan-jun

2011-12-01

A MOEMS micro-mirror spectrometer, which uses micro-mirror as a light switch so that spectrum can be detected by a single detector, has the advantages of transforming DC into AC, applying Hadamard transform optics without additional template, high pixel resolution and low cost. In this spectrometer, the vital problem is the conflict between the scales of slit and the light intensity. Hence, in order to improve the resolution of this spectrometer, the present paper gives the analysis of the new effects caused by micro structure, and optimal values of the key factors. Firstly, the effects of diffraction limitation, spatial sample rate and curved slit image on the resolution of the spectrum were proposed. Then, the results were simulated; the key values were tested on the micro mirror spectrometer. Finally, taking all these three effects into account, this micro system was optimized. With a scale of 70 mm x 130 mm, decreasing the height of the image at the plane of micro mirror can not diminish the influence of curved slit image in the spectrum; under the demand of spatial sample rate, the resolution must be twice over the pixel resolution; only if the width of the slit is 1.818 microm and the pixel resolution is 2.2786 microm can the spectrometer have the best performance.

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

Acciarri, R.; Adams, C.; An, R.

Here, we present several studies of convolutional neural networks applied to data coming from the MicroBooNE detector, a liquid argon time projection chamber (LArTPC). The algorithms studied include the classification of single particle images, the localization of single particle and neutrino interactions in an image, and the detection of a simulated neutrino event overlaid with cosmic ray backgrounds taken from real detector data. These studies demonstrate the potential of convolutional neural networks for particle identification or event detection on simulated neutrino interactions. Lastly, we also address technical issues that arise when applying this technique to data from a large LArTPCmore » at or near ground level.« less

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

Acciarri, R.; Adams, C.; An, R.

We present several studies of convolutional neural networks applied to data coming from the MicroBooNE detector, a liquid argon time projection chamber (LArTPC). The algorithms studied include the classification of single particle images, the localization of single particle and neutrino interactions in an image, and the detection of a simulated neutrino event overlaid with cosmic ray backgrounds taken from real detector data. These studies demonstrate the potential of convolutional neural networks for particle identification or event detection on simulated neutrino interactions. We also address technical issues that arise when applying this technique to data from a large LArTPC at ormore » near ground level.« less

A focal plane metrology system and PSF centroiding experiment

NASA Astrophysics Data System (ADS)

Li, Haitao; Li, Baoquan; Cao, Yang; Li, Ligang

2016-10-01

In this paper, we present an overview of a detector array equipment metrology testbed and a micro-pixel centroiding experiment currently under development at the National Space Science Center, Chinese Academy of Sciences. We discuss on-going development efforts aimed at calibrating the intra-/inter-pixel quantum efficiency and pixel positions for scientific grade CMOS detector, and review significant progress in achieving higher precision differential centroiding for pseudo star images in large area back-illuminated CMOS detector. Without calibration of pixel positions and intrapixel response, we have demonstrated that the standard deviation of differential centroiding is below 2.0e-3 pixels.

SU-F-T-180: Evaluation of a Scintillating Screen Detector for Proton Beam QA and Acceptance Testing

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

Ghebremedhin, A; Taber, M; Koss, P

2016-06-15

Purpose: To test the performance of a commercial scintillating screen detector for acceptance testing and Quality Assurance of a proton pencil beam scanning system. Method: The detector (Lexitek DRD 400) has 40cm × 40cm field, uses a thin scintillator imaged onto a 16-bit scientific CCD with ∼0.5mm resolution. A grid target and LED illuminators are provided for spatial calibration and relative gain correction. The detector mounts to the nozzle with micron precision. Tools are provided for image processing and analysis of single or multiple Gaussian spots. Results: The bias and gain of the detector were studied to measure repeatability andmore » accuracy. Gain measurements were taken with the LED illuminators to measure repeatability and variation of the lens-CCD pair as a function with f-stop. Overall system gain was measured with a passive scattering (broad) beam whose shape is calibrated with EDR film placed in front of the scintillator. To create a large uniform field, overlapping small fields were recorded with the detector translated laterally and stitched together to cover the full field. Due to the long exposures required to obtain multiple spills of the synchrotron and very high detector sensitivity, borated polyethylene shielding was added to reduce direct radiation events hitting the CCD. Measurements with a micro ion chamber were compared to the detector’s spot profile. Software was developed to process arrays of Gaussian spots and to correct for radiation events. Conclusion: The detector background has a fixed bias, a small component linear in time, and is easily corrected. The gain correction method was validated with 2% accuracy. The detector spot profile matches the micro ion chamber data over 4 orders of magnitude. The multiple spot analyses can be easily used with plan data for measuring pencil beam uniformity and for regular QA comparison.« less

Micro-attenuated total reflection spectral imaging in archaeology: application to Maya paint and plaster wall decorations.

PubMed

Goodall, Rosemary A; Hall, Jay; Sharer, Robert J; Traxler, Loa; Rintoul, Llew; Fredericks, Peter M

2008-01-01

Fourier transform infrared (FT-IR) attenuated total reflection (ATR) imaging has been successfully used to identify individual mineral components of ancient Maya paint. The high spatial resolution of a micro FT-IR-ATR system in combination with a focal plane array detector has allowed individual particles in the paint to be resolved and identified from their spectra. This system has been used in combination with micro-Raman spectroscopy to characterize the paint, which was found to be a mixture of hematite and silicate particles with minor amounts of calcite, carbon, and magnetite particles in a sub-micrometer hematite and calcite matrix. The underlying stucco was also investigated and found to be a combination of calcite with fine carbon particles, making a dark sub-ground for the paint.

MicroPET II: design, development and initial performance of an improved microPET scanner for small-animal imaging

NASA Astrophysics Data System (ADS)

Tai, Yuan-Chuan; Chatziioannou, Arion F.; Yang, Yongfeng; Silverman, Robert W.; Meadors, Ken; Siegel, Stefan; Newport, Danny F.; Stickel, Jennifer R.; Cherry, Simon R.

2003-06-01

MicroPET II is a second-generation animal PET scanner designed for high-resolution imaging of small laboratory rodents. The system consists of 90 scintillation detector modules arranged in three contiguous axial rings with a ring diameter of 16.0 cm and an axial length of 4.9 cm. Each detector module consists of a 14 × 14 array of lutetium oxyorthosilicate (LSO) crystals coupled to a multi-channel photomultiplier tube (MC-PMT) through a coherent optical fibre bundle. Each LSO crystal element measures 0.975 mm × 0.975 mm in cross section by 12.5 mm in length. A barium sulphate reflector material was used between LSO elements leading to a detector pitch of 1.15 mm in both axial and transverse directions. Fused optical fibre bundles were made from 90 µm diameter glass fibres with a numerical aperture of 0.56. Interstitial extramural absorber was added between the fibres to reduce optical cross talk. A charge-division readout circuit was implemented on printed circuit boards to decode the 196 crystals in each array from the outputs of the 64 anode signals of the MC-PMT. Electronics from Concorde Microsystems Inc. (Knoxville, TN) were used for signal amplification, digitization, event qualification, coincidence processing and data capture. Coincidence data were passed to a host PC that recorded events in list mode. Following acquisition, data were sorted into sinograms and reconstructed using Fourier rebinning and filtered backprojection algorithms. Basic evaluation of the system has been completed. The absolute sensitivity of the microPET II scanner was 2.26% at the centre of the field of view (CFOV) for an energy window of 250-750 keV and a timing window of 10 ns. The intrinsic spatial resolution of the detectors in the system averaged 1.21 mm full width at half maximum (FWHM) when measured with a 22Na point source 0.5 mm in diameter. Reconstructed image resolution ranged from 0.83 mm FWHM at the CFOV to 1.47 mm FWHM in the radial direction, 1.17 mm FWHM in the tangential direction and 1.42 mm FWHM in the axial direction at 1 cm offset from the CFOV. These values represent highly significant improvements over our earlier microPET scanner (approximately fourfold sensitivity increase and 25-35% improvement in linear spatial resolution under equivalent operating conditions) and are expected to be further improved when the system is fully optimized. This work was originally conducted at UCLA, Crump Institute for Molecular Imaging, and was continued and completed at UC Davis, Department of Biomedical Engineering.

Micro-optics for simultaneous multi-spectral imaging applied to chemical/biological and IED detection

NASA Astrophysics Data System (ADS)

Hinnrichs, Michele

2012-06-01

Using diffractive micro-lenses configured in an array and placed in close proximity to the focal plane array will enable a small compact simultaneous multispectral imaging camera. This approach can be applied to spectral regions from the ultraviolet (UV) to the long-wave infrared (LWIR). The number of simultaneously imaged spectral bands is determined by the number of individually configured diffractive optical micro-lenses (lenslet) in the array. Each lenslet images at a different wavelength determined by the blaze and set at the time of manufacturing based on application. In addition, modulation of the focal length of the lenslet array with piezoelectric or electro-static actuation will enable spectral band fill-in allowing hyperspectral imaging. Using the lenslet array with dual-band detectors will increase the number of simultaneous spectral images by a factor of two when utilizing multiple diffraction orders. Configurations and concept designs will be presented for detection application for biological/chemical agents, buried IED's and reconnaissance. The simultaneous detection of multiple spectral images in a single frame of data enhances the image processing capability by eliminating temporal differences between colors and enabling a handheld instrument that is insensitive to motion.

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

DOE PAGES

Fast, J.

2017-02-16

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

A Muon Tomography Station with GEM Detectors for Nuclear Threat Detection

NASA Astrophysics Data System (ADS)

Staib, Michael; Gnanvo, Kondo; Grasso, Leonard; Hohlmann, Marcus; Locke, Judson; Costa, Filippo; Martoiu, Sorin; Muller, Hans

2011-10-01

Muon tomography for homeland security aims at detecting well-shielded nuclear contraband in cargo and imaging it in 3D. The technique exploits multiple scattering of atmospheric cosmic ray muons, which is stronger in dense, high-Z nuclear materials, e.g. enriched uranium, than in low-Z and medium-Z shielding materials. We have constructed and operated a compact Muon Tomography Station (MTS) that tracks muons with six to ten 30 cm x 30 cm Triple Gas Electron Multiplier (GEM) detectors placed on the sides of a 27-liter cubic imaging volume. The 2D strip readouts of the GEMs achieve a spatial resolution of ˜130 μm in both dimensions and the station is operated at a muon trigger rate of ˜20 Hz. The 1,536 strips per GEM detector are read out with the first medium-size implementation of the Scalable Readout System (SRS) developed specifically for Micro-Pattern Gas Detectors by the RD51 collaboration at CERN. We discuss the performance of this MTS prototype and present experimental results on tomographic imaging of high-Z objects with and without shielding.

Development of a Timepix based detector for the NanoXCT project

NASA Astrophysics Data System (ADS)

Nachtrab, F.; Hofmann, T.; Speier, C.; Lučić, J.; Firsching, M.; Uhlmann, N.; Takman, P.; Heinzl, C.; Holmberg, A.; Krumm, M.; Sauerwein, C.

2015-11-01

The NanoXCT EU FP7 project [1] aims at developing a laboratory, i.e. bench top sized X-ray nano-CT system with a large field-of-view (FOV) for non-destructive testing needs in the micro- and nano-technology sector. The targeted voxel size is 50 nm at 0.175 mm FOV, the maximum FOV is 1 mm at 285 nm voxel size. Within the project a suitable X-ray source, detector and manipulation system have been developed. The system concept [2] omits the use of X-ray optics, to be able to provide a large FOV of up to 1 mm and to preserve the flexibility of state-of-the-art micro-CT systems. The targeted resolution will be reached via direct geometric magnification made possible by the development of a specialized high-flux nano-focus transmission X-ray tube. The end-user's demand for elemental analysis will be covered by energy-resolved measurement techniques, in particular a K-edge imaging method. Timepix [3] modules were chosen as the basis for the detector system, since a photon counting detector is advantageous for the long exposure times that come with very small focal spot sizes. Additional advantages are the small pixel size and adjustable energy threshold. To fulfill the requirements on field-of-view, a detector width 0> 300 pixels was needed. The NanoXCT detector consists of four Hexa modules with 500 μm silicon sensors supplied by X-ray Imaging Europe. An adapter board was developed to connect all four modules to one Fitpix3 readout. The final detector has an active area of 3072 × 512 pixels or approximately 17 × 3 cm2.In this contribution we present the development of the Timepix based NanoXCT detector, it's application in the NanoXCT project for CT and material specific measurements and the current status of results.

Development of high energy micro-tomography system at SPring-8

NASA Astrophysics Data System (ADS)

Uesugi, Kentaro; Hoshino, Masato

2017-09-01

A high energy X-ray micro-tomography system has been developed at BL20B2 in SPring-8. The available range of the energy is between 20keV and 113keV with a Si (511) double crystal monochromator. The system enables us to image large or heavy materials such as fossils and metals. The X-ray image detector consists of visible light conversion system and sCMOS camera. The effective pixel size is variable by changing a tandem lens between 6.5 μm/pixel and 25.5 μm/pixel discretely. The format of the camera is 2048 pixels x 2048 pixels. As a demonstration of the system, alkaline battery and a nodule from Bolivia were imaged. A detail of the structure of the battery and a female mold Trilobite were successfully imaged without breaking those fossils.

Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications

NASA Astrophysics Data System (ADS)

Wei, Qingyang; Wang, Shi; Ma, Tianyu; Wu, Jing; Liu, Hui; Xu, Tianpeng; Xia, Yan; Fan, Peng; Lyu, Zhenlei; Liu, Yaqiang

2015-06-01

PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted on the system and inserted into the detector ring in SPECT imaging mode. A cone-beam CT consisting of a micro focus X-ray tube and a CMOS detector is implemented. The detailed design and the performance evaluations are reported in this paper. In PET imaging mode, the measured NEMA based spatial resolution is 2.12 mm (FWHM), and the sensitivity at the central field of view (CFOV) is 3.2%. The FOV size is 50 mm (∅)×100 mm (L). The SPECT has a spatial resolution of 1.32 mm (FWHM) and an average sensitivity of 0.031% at the center axial, and a 30 mm (∅)×90 mm (L) FOV. The CT spatial resolution is 8.32 lp/mm @10%MTF, and the contrast discrimination function value is 2.06% with 1.5 mm size cubic box object. In conclusion, a compact, tri-modality PET/SPECT/CT system was successfully built with low cost and high performance.

Synchrotron radiation microimaging in rabbit models of cancer for preclinical testing

NASA Astrophysics Data System (ADS)

Umetani, Keiji; Uesugi, Kentaro; Kobatake, Makito; Yamamoto, Akira; Yamashita, Takenori; Imai, Shigeki

2009-10-01

Preclinical laboratory animal imaging modalities such as microangiography and micro-computed tomography (micro-CT) have been developed at the SPring-8 BL20B2 bending magnet beamline. The objective of this paper is to demonstrate the usefulness of microangiography systems for physiological examinations of live animals and micro-CT systems for postmortem morphological examinations. Synchrotron radiation microangiography and micro-CT with contrast agents present the main advantageous capability of depicting the anatomy of small blood vessels with tens of micrometers' diameter. This paper reports two imaging instrument types and their respective applications to preclinical imaging of tumor angiogenic blood vessels in tumor-bearing rabbits, where tumor angiogenesis is characterized morphologically by an increased number of blood vessels. A microangiography system with spatial resolution around 10 μm has been used for therapeutically evaluating angiogenic vessels in a rabbit model of cancer for evaluating embolization materials in transcatheter arterial embolization and for radiation therapy. After an iodine contrast agent was injected into an artery, in vivo imaging was carried out using a high-resolution real-time detector incorporating an X-ray direct-conversion-type SATICON pickup tube. On the other hand, a micro-CT system capably performed three-dimensional visualization of tumor angiogenic blood vessels using tumor-transplanted rabbit specimens with a barium sulfate contrast agent injected into the blood vessels. For specimen imaging, a large-field high-resolution micro-CT system based on a 10-megapixel CCD camera was developed to study tumor-associated alterations in angioarchitecture. Evidence of increased vascularity by tumor angiogenesis and decreased vascularity by tumor treatments was achieved by physiological evaluation of angiogenic small blood vessels in microangiographic imaging and by morphological assessment in micro-CT imaging. These results demonstrate the accuracy and usefulness of microangiography and micro-CT systems for quantitative examination of animals' angioarchitecture, respectively, during live and postmortem examinations.

A 90GHz Bolometer Camera Detector System for the Green Bank Telescope

NASA Technical Reports Server (NTRS)

Benford, Dominic J.; Allen, Christine A.; Buchanan, Ernest D.; Chen, Tina C.; Chervenak, James A.; Devlin, Mark J.; Dicker, Simon R.; Forgione, Joshua B.

2004-01-01

We describe a close-packed, two-dimensional imaging detector system for operation at 90GHz (3.3mm) for the 100 m Green Bank Telescope (GBT) This system will provide high sensitivity (<1mjy in 1s rapid imaging (15'x15' to 250 microJy in 1 hr) at the world's largest steerable aperture. The heart of this camera is an 8x8 close packed, Nyquist-sampled array of superconducting transition edge sensor bolometers. We have designed and are producing a functional superconducting bolometer array system using a monolithic planar architecture and high-speed multiplexed readout electronics. With an NEP of approx. 2.10(exp 17) W/square root Hz, the TES bolometers will provide fast linear sensitive response for high performance imaging. The detectors are read out by and 8x8 time domain SQUID multiplexer. A digital/analog electronics system has been designed to enable read out by SQUID multiplexers. First light for this instrument on the GBT is expected within a year.

Convolutional neural networks applied to neutrino events in a liquid argon time projection chamber

NASA Astrophysics Data System (ADS)

Acciarri, R.; Adams, C.; An, R.; Asaadi, J.; Auger, M.; Bagby, L.; Baller, B.; Barr, G.; Bass, M.; Bay, F.; Bishai, M.; Blake, A.; Bolton, T.; Bugel, L.; Camilleri, L.; Caratelli, D.; Carls, B.; Castillo Fernandez, R.; Cavanna, F.; Chen, H.; Church, E.; Cianci, D.; Collin, G. H.; Conrad, J. M.; Convery, M.; Crespo-Anadón, J. I.; Del Tutto, M.; Devitt, D.; Dytman, S.; Eberly, B.; Ereditato, A.; Escudero Sanchez, L.; Esquivel, J.; Fleming, B. T.; Foreman, W.; Furmanski, A. P.; Garvey, G. T.; Genty, V.; Goeldi, D.; Gollapinni, S.; Graf, N.; Gramellini, E.; Greenlee, H.; Grosso, R.; Guenette, R.; Hackenburg, A.; Hamilton, P.; Hen, O.; Hewes, J.; Hill, C.; Ho, J.; Horton-Smith, G.; James, C.; de Vries, J. Jan; Jen, C.-M.; Jiang, L.; Johnson, R. A.; Jones, B. J. P.; Joshi, J.; Jostlein, H.; Kaleko, D.; Karagiorgi, G.; Ketchum, W.; Kirby, B.; Kirby, M.; Kobilarcik, T.; Kreslo, I.; Laube, A.; Li, Y.; Lister, A.; Littlejohn, B. R.; Lockwitz, S.; Lorca, D.; Louis, W. C.; Luethi, M.; Lundberg, B.; Luo, X.; Marchionni, A.; Mariani, C.; Marshall, J.; Martinez Caicedo, D. A.; Meddage, V.; Miceli, T.; Mills, G. B.; Moon, J.; Mooney, M.; Moore, C. D.; Mousseau, J.; Murrells, R.; Naples, D.; Nienaber, P.; Nowak, J.; Palamara, O.; Paolone, V.; Papavassiliou, V.; Pate, S. F.; Pavlovic, Z.; Porzio, D.; Pulliam, G.; Qian, X.; Raaf, J. L.; Rafique, A.; Rochester, L.; von Rohr, C. Rudolf; Russell, B.; Schmitz, D. W.; Schukraft, A.; Seligman, W.; Shaevitz, M. H.; Sinclair, J.; Snider, E. L.; Soderberg, M.; Söldner-Rembold, S.; Soleti, S. R.; Spentzouris, P.; Spitz, J.; St. John, J.; Strauss, T.; Szelc, A. M.; Tagg, N.; Terao, K.; Thomson, M.; Toups, M.; Tsai, Y.-T.; Tufanli, S.; Usher, T.; Van de Water, R. G.; Viren, B.; Weber, M.; Weston, J.; Wickremasinghe, D. A.; Wolbers, S.; Wongjirad, T.; Woodruff, K.; Yang, T.; Zeller, G. P.; Zennamo, J.; Zhang, C.

2017-03-01

We present several studies of convolutional neural networks applied to data coming from the MicroBooNE detector, a liquid argon time projection chamber (LArTPC). The algorithms studied include the classification of single particle images, the localization of single particle and neutrino interactions in an image, and the detection of a simulated neutrino event overlaid with cosmic ray backgrounds taken from real detector data. These studies demonstrate the potential of convolutional neural networks for particle identification or event detection on simulated neutrino interactions. We also address technical issues that arise when applying this technique to data from a large LArTPC at or near ground level.

Optimisation of a propagation-based x-ray phase-contrast micro-CT system

NASA Astrophysics Data System (ADS)

Nesterets, Yakov I.; Gureyev, Timur E.; Dimmock, Matthew R.

2018-03-01

Micro-CT scanners find applications in many areas ranging from biomedical research to material sciences. In order to provide spatial resolution on a micron scale, these scanners are usually equipped with micro-focus, low-power x-ray sources and hence require long scanning times to produce high resolution 3D images of the object with acceptable contrast-to-noise. Propagation-based phase-contrast tomography (PB-PCT) has the potential to significantly improve the contrast-to-noise ratio (CNR) or, alternatively, reduce the image acquisition time while preserving the CNR and the spatial resolution. We propose a general approach for the optimisation of the PB-PCT imaging system. When applied to an imaging system with fixed parameters of the source and detector this approach requires optimisation of only two independent geometrical parameters of the imaging system, i.e. the source-to-object distance R 1 and geometrical magnification M, in order to produce the best spatial resolution and CNR. If, in addition to R 1 and M, the system parameter space also includes the source size and the anode potential this approach allows one to find a unique configuration of the imaging system that produces the required spatial resolution and the best CNR.

A large area high resolution imaging detector for fast atom diffraction

NASA Astrophysics Data System (ADS)

Lupone, Sylvain; Soulisse, Pierre; Roncin, Philippe

2018-07-01

We describe a high resolution imaging detector based on a single 80 mm micro-channel-plate (MCP) and a phosphor screen mounted on a UHV flange of only 100 mm inner diameter. It relies on standard components and we describe its performance with one or two MCPs. A resolution of 80 μm rms is observed on the beam profile. At low count rate, individual impact can be pinpointed with few μm accuracy but the resolution is probably limited by the MCP channel diameter. The detector has been used to record the diffraction of fast atoms at grazing incidence on crystal surfaces (GIFAD), a technique probing the electronic density of the topmost layer only. The detector was also used to record the scattering profile during azimuthal scan of the crystal to produce triangulation curves revealing the surface crystallographic directions of molecular layers. It should also be compatible with reflection high energy electron (RHEED) experiment when fragile surfaces require a low exposure to the electron beam. The discussions on the mode of operation specific to diffraction experiments apply also to commercial detectors.

Micro- and nano-imaging at the diamond beamline I13L-imaging and coherence

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

Rau, C., E-mail: Christoph.rau@diamond.ac.uk; University of Manchester, School of Materials Grosvenor St., Manchester, M1 7HS; Northwestern University School of Medicine, 303 E. Chicago Avenue, Chicago, IL 60611-3008

2016-07-27

The Diamond Beamline I13L is dedicated to imaging on the micron- and nano-lengthscale, operating in the energy range between 6 and 30 keV. For this purpose two independent stations have been built. The imaging branch is fully operational for micro-tomography and in-line phase contrast imaging with micrometer resolution. Currently a full-field microscope providing 50nm spatial resolution over a field of view of 100 µm is being tested. On the coherence branch, coherent diffraction imaging techniques such as ptychography and coherent X-ray Bragg diffraction are currently developed. The beamline contains a number of unique features. The machine layout has been modifiedmore » to the so-called mini-beta scheme, providing significantly increased flux from the two canted undulators. New instrumental designs such as a robot arm for the detector in diffraction experiments have been employed. The imaging branch is operated in collaboration with Manchester University, called therefore the Diamond-Manchester Branchline.« less

Preliminary experimental results from a MARS Micro-CT system.

PubMed

He, Peng; Yu, Hengyong; Thayer, Patrick; Jin, Xin; Xu, Qiong; Bennett, James; Tappenden, Rachael; Wei, Biao; Goldstein, Aaron; Renaud, Peter; Butler, Anthony; Butler, Phillip; Wang, Ge

2012-01-01

The Medipix All Resolution System (MARS) system is a commercial spectral/multi-energy micro-CT scanner designed and assembled by the MARS Bioimaging, Ltd. in New Zealand. This system utilizes the state-of-the-art Medipix photon-counting, energy-discriminating detector technology developed by a collaboration at European Organization for Nuclear Research (CERN). In this paper, we report our preliminary experimental results using this system, including geometrical alignment, photon energy characterization, protocol optimization, and spectral image reconstruction. We produced our scan datasets with a multi-material phantom, and then applied ordered subset-simultaneous algebraic reconstruction technique (OS-SART) to reconstruct images in different energy ranges and principal component analysis (PCA) to evaluate spectral deviation among the energy ranges.

Micro-Imagers for Spaceborne Cell-Growth Experiments

NASA Technical Reports Server (NTRS)

Behar, Alberto; Matthews, Janet; SaintAnge, Beverly; Tanabe, Helen

2006-01-01

A document discusses selected aspects of a continuing effort to develop five micro-imagers for both still and video monitoring of cell cultures to be grown aboard the International Space Station. The approach taken in this effort is to modify and augment pre-existing electronic micro-cameras. Each such camera includes an image-detector integrated-circuit chip, signal-conditioning and image-compression circuitry, and connections for receiving power from, and exchanging data with, external electronic equipment. Four white and four multicolor light-emitting diodes are to be added to each camera for illuminating the specimens to be monitored. The lens used in the original version of each camera is to be replaced with a shorter-focal-length, more-compact singlet lens to make it possible to fit the camera into the limited space allocated to it. Initially, the lenses in the five cameras are to have different focal lengths: the focal lengths are to be 1, 1.5, 2, 2.5, and 3 cm. Once one of the focal lengths is determined to be the most nearly optimum, the remaining four cameras are to be fitted with lenses of that focal length.

A novel x-ray detector design with higher DQE and reduced aliasing: Theoretical analysis of x-ray reabsoprtion in detector converter material

NASA Astrophysics Data System (ADS)

Nano, Tomi; Escartin, Terenz; Karim, Karim S.; Cunningham, Ian A.

2016-03-01

The ability to improve visualization of structural information in digital radiography without increasing radiation exposures requires improved image quality across all spatial frequencies, especially at high frequencies. The detective quantum efficiency (DQE) as a function of spatial frequency quantifies image quality given by an x-ray detector. We present a method of increasing DQE at high spatial frequencies by improving the modulation transfer function (MTF) and reducing noise aliasing. The Apodized Aperature Pixel (AAP) design uses a detector with micro-elements to synthesize desired pixels and provide higher DQE than conventional detector designs. A cascaded system analysis (CSA) that incorporates x-ray interactions is used for comparison of the theoretical MTF, noise power spectrum (NPS), and DQE. Signal and noise transfer through the converter material is shown to consist of correlated an uncorrelated terms. The AAP design was shown to improve the DQE of both material types that have predominantly correlated transfer (such as CsI) and predominantly uncorrelated transfer (such as Se). Improvement in the MTF by 50% and the DQE by 100% at the sampling cut-off frequency is obtained when uncorrelated transfer is prevalent through the converter material. Optimizing high-frequency DQE results in improved image contrast and visualization of small structures and fine-detail.

THERMAP : a mid-infrared spectro-imager for the Marco Polo R mission

NASA Astrophysics Data System (ADS)

Groussin, O.; Brageot, E.; Reynaud, J.-L.; Lamy, P.; Jorda, L.; Licandro, J.; Helbert, J.; Knollenberg, J.; Kührt, E.; Delbó, M.

2012-09-01

We present THERMAP, a mid-infrared (8-16 μm) spectro-imager based on uncooled micro-bolometer detector arrays. Due to the recent technological development of these detectors, which have undergone significant improvements in the last decade, we wanted to test their performances for a space mission to small bodies in the inner Solar System. THERMAP was selected by ESA in January 2012 for a one year assessment study, in the framework of a call for declaration of interest in science instrumentation for the Marco Polo R Cosmic Vision mission. In this paper, we present some results of this study and in particular demonstrate that the new generation of uncooled micro-bolometer detectors has all the imaging and spectroscopic capabilities to fulfill the scientific objectives of the Marco Polo R mission. THERMAP scientific objectives - The midinfrared instrument of the Marco Polo R mission must be able i) to determine the surface temperature by mapping the entire surface with an absolute accuracy of at least 5 K (goal 1 K) above 200 K, ii) to determine the thermal inertia with an accuracy of 10% and iii) to determine the surface composition by mapping the entire surface with a spectral resolution of 70 between 8 and 16 μm. The above mappings should be performed with a spatial resolution of 10 m for the entire surface (global characterization) and 10 cm for the sampling sites (local characterization). THERMAP imaging capabilities - In order to test the imaging capabilities of the THERMAP uncooled microbolometer detector, we set up an experiment based on a 640x480 ULIS micro-bolometer array, a germanium objective and a black body. Using the results of this experiment, we show that calibrated radiometric images can be obtained down to at least 258 K (lower limit of our experiment), and that two calibration points are sufficient to determine the absolute scene temperature with an accuracy better than 1.5 K. An extrapolation to lower temperatures provides an accuracy of about 5 K at 180 K, the lowest temperature the detector can measure. THERMAP spectroscopic capabilites - In order to test the spectroscopic performances of the detector, we added flux attenuating neutral density mid-infrared filters (transmittance: 50%, 10%, 1%) to our experiment. Our results show that we can perform spectroscopic measurements with a spectral resolution R=40-80 in the wavelength range 8-16 μm for a scene temperature larger than 300 K, the typical surface temperature of a Near Earth Asteroid at 1 AU from the Sun. THERMAP preliminary design - From the above results, we defined a preliminary design for the instrument. THERMAP is a mid-infrared (8-16 μm) spectro-imager based on two uncooled microbolometer arrays. It is composed of two channels, one for imaging and one for spectroscopy. A flip mirror allows switching between the two channels. Calibration is performed using deep space and two black bodies at known temperature. The design of the THERMAP instrument has a strong heritage from the MERTIS instrument on board Bepi-Colombo [1], which guarantees its feasibility and reliability. Our design is very flexible in term of operations, which is fundamental for a mission to a binary asteroid system (1996 FG3). The THERMAP instrument will be proposed for Marco Polo R and any future space missions to small bodies in the inner solar system.

Cochlear Implant Electrode Localization Using an Ultra-High Resolution Scan Mode on Conventional 64-Slice and New Generation 192-Slice Multi-Detector Computed Tomography.

PubMed

Carlson, Matthew L; Leng, Shuai; Diehn, Felix E; Witte, Robert J; Krecke, Karl N; Grimes, Josh; Koeller, Kelly K; Bruesewitz, Michael R; McCollough, Cynthia H; Lane, John I

2017-08-01

A new generation 192-slice multi-detector computed tomography (MDCT) clinical scanner provides enhanced image quality and superior electrode localization over conventional MDCT. Currently, accurate and reliable cochlear implant electrode localization using conventional MDCT scanners remains elusive. Eight fresh-frozen cadaveric temporal bones were implanted with full-length cochlear implant electrodes. Specimens were subsequently scanned with conventional 64-slice and new generation 192-slice MDCT scanners utilizing ultra-high resolution modes. Additionally, all specimens were scanned with micro-CT to provide a reference criterion for electrode position. Images were reconstructed according to routine temporal bone clinical protocols. Three neuroradiologists, blinded to scanner type, reviewed images independently to assess resolution of individual electrodes, scalar localization, and severity of image artifact. Serving as the reference standard, micro-CT identified scalar crossover in one specimen; imaging of all remaining cochleae demonstrated complete scala tympani insertions. The 192-slice MDCT scanner exhibited improved resolution of individual electrodes (p < 0.01), superior scalar localization (p < 0.01), and reduced blooming artifact (p < 0.05), compared with conventional 64-slice MDCT. There was no significant difference between platforms when comparing streak or ring artifact. The new generation 192-slice MDCT scanner offers several notable advantages for cochlear implant imaging compared with conventional MDCT. This technology provides important feedback regarding electrode position and course, which may help in future optimization of surgical technique and electrode design.

Designing an Active Target Test Projection Chamber

NASA Astrophysics Data System (ADS)

Koci, James; Tan Ahn Collaboration, Dr.; Nicolas Dixneuf Collaboration

2015-10-01

The development of instrumentation in nuclear physics is crucial for advancing our ability to measure the properties of exotic nuclei. One limitation of the use of exotic nuclei in experiment is their very low production intensities. Recently, detectors, called active-target dectectors, have been developed to address this issue. Active-target detectors use a gas medium to image charged-particle tracks that are emitted in nuclear reactions. Last semester, I designed a vacuum chamber to be used in developing Micro-Pattern Gas detectors that will upgrade the capabilities of an active-target detector called the Prototype AT-TPC. With the exterior of the chamber complete, I have now been using an electric field modeling program, Garfield, developed by CERN to design a field cage to be placed within the vacuum chamber. The field cage will be a box-like apparatus consisting of two parallel metal plates connected with a resistor chain and attached to wires wrapped between them. The cage will provide a uniform electric field within the chamber to drift electrons from nuclear reactions down to the detector in the bottom of the chamber. These signals are then amplified by a proportional counter, and the data is sent to a computer. For the long term, we would like to incorporate a Micro-Pattern Gas Detectors in the interior of the chamber and eventually use the AT-TPC to examine various nuclei. Dr. Ahn is my advising professor.

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.

Assessment of a New High-Performance Small-Animal X-Ray Tomograph

NASA Astrophysics Data System (ADS)

Vaquero, J. J.; Redondo, S.; Lage, E.; Abella, M.; Sisniega, A.; Tapias, G.; Montenegro, M. L. Soto; Desco, M.

2008-06-01

We have developed a new X-ray cone-beam tomograph for in vivo small-animal imaging using a flat panel detector (CMOS technology with a microcolumnar CsI scintillator plate) and a microfocus X-ray source. The geometrical configuration was designed to achieve a spatial resolution of about 12 lpmm with a field of view appropriate for laboratory rodents. In order to achieve high performance with regard to per-animal screening time and cost, the acquisition software takes advantage of the highest frame rate of the detector and performs on-the-fly corrections on the detector raw data. These corrections include geometrical misalignments, sensor non-uniformities, and defective elements. The resulting image is then converted to attenuation values. We measured detector modulation transfer function (MTF), detector stability, system resolution, quality of the reconstructed tomographic images and radiated dose. The system resolution was measured following the standard test method ASTM E 1695 -95. For image quality evaluation, we assessed signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as a function of the radiated dose. Dose studies for different imaging protocols were performed by introducing TLD dosimeters in representative organs of euthanized laboratory rats. Noise figure, measured as standard deviation, was 50 HU for a dose of 10 cGy. Effective dose with standard research protocols is below 200 mGy, confirming that the system is appropriate for in vivo imaging. Maximum spatial resolution achieved was better than 50 micron. Our experimental results obtained with image quality phantoms as well as with in-vivo studies show that the proposed configuration based on a CMOS flat panel detector and a small micro-focus X-ray tube leads to a compact design that provides good image quality and low radiated dose, and it could be used as an add-on for existing PET or SPECT scanners.

Scout-view Assisted Interior Micro-CT

PubMed Central

Sen Sharma, Kriti; Holzner, Christian; Vasilescu, Dragoş M.; Jin, Xin; Narayanan, Shree; Agah, Masoud; Hoffman, Eric A.; Yu, Hengyong; Wang, Ge

2013-01-01

Micro computed tomography (micro-CT) is a widely-used imaging technique. A challenge of micro-CT is to quantitatively reconstruct a sample larger than the field-of-view (FOV) of the detector. This scenario is characterized by truncated projections and associated image artifacts. However, for such truncated scans, a low resolution scout scan with an increased FOV is frequently acquired so as to position the sample properly. This study shows that the otherwise discarded scout scans can provide sufficient additional information to uniquely and stably reconstruct the interior region of interest. Two interior reconstruction methods are designed to utilize the multi-resolution data without a significant computational overhead. While most previous studies used numerically truncated global projections as interior data, this study uses truly hybrid scans where global and interior scans were carried out at different resolutions. Additionally, owing to the lack of standard interior micro-CT phantoms, we designed and fabricated novel interior micro-CT phantoms for this study to provide means of validation for our algorithms. Finally, two characteristic samples from separate studies were scanned to show the effect of our reconstructions. The presented methods show significant improvements over existing reconstruction algorithms. PMID:23732478

Nano-Computed Tomography: Technique and Applications.

PubMed

Kampschulte, M; Langheinirch, A C; Sender, J; Litzlbauer, H D; Althöhn, U; Schwab, J D; Alejandre-Lafont, E; Martels, G; Krombach, G A

2016-02-01

Nano-computed tomography (nano-CT) is an emerging, high-resolution cross-sectional imaging technique and represents a technical advancement of the established micro-CT technology. Based on the application of a transmission target X-ray tube, the focal spot size can be decreased down to diameters less than 400 nanometers (nm). Together with specific detectors and examination protocols, a superior spatial resolution up to 400 nm (10 % MTF) can be achieved, thereby exceeding the resolution capacity of typical micro-CT systems. The technical concept of nano-CT imaging as well as the basics of specimen preparation are demonstrated exemplarily. Characteristics of atherosclerotic plaques (intraplaque hemorrhage and calcifications) in a murine model of atherosclerosis (ApoE (-/-)/LDLR(-/-) double knockout mouse) are demonstrated in the context of superior spatial resolution in comparison to micro-CT. Furthermore, this article presents the application of nano-CT for imaging cerebral microcirculation (murine), lung structures (porcine), and trabecular microstructure (ovine) in contrast to micro-CT imaging. This review shows the potential of nano-CT as a radiological method in biomedical basic research and discusses the application of experimental, high resolution CT techniques in consideration of other high resolution cross-sectional imaging techniques. Nano-computed tomography is a high resolution CT-technology for 3D imaging at sub-micrometer resolution. The technical concept bases on a further development of the established ex-vivo-micro-CT technology. By improvement of the spatial resolution, structures at a cellular level become visible (e.g. osteocyte lacunae). © Georg Thieme Verlag KG Stuttgart · New York.

Biological object recognition in μ-radiography images

NASA Astrophysics Data System (ADS)

Prochazka, A.; Dammer, J.; Weyda, F.; Sopko, V.; Benes, J.; Zeman, J.; Jandejsek, I.

2015-03-01

This study presents an applicability of real-time microradiography to biological objects, namely to horse chestnut leafminer, Cameraria ohridella (Insecta: Lepidoptera, Gracillariidae) and following image processing focusing on image segmentation and object recognition. The microradiography of insects (such as horse chestnut leafminer) provides a non-invasive imaging that leaves the organisms alive. The imaging requires a high spatial resolution (micrometer scale) radiographic system. Our radiographic system consists of a micro-focus X-ray tube and two types of detectors. The first is a charge integrating detector (Hamamatsu flat panel), the second is a pixel semiconductor detector (Medipix2 detector). The latter allows detection of single quantum photon of ionizing radiation. We obtained numerous horse chestnuts leafminer pupae in several microradiography images easy recognizable in automatic mode using the image processing methods. We implemented an algorithm that is able to count a number of dead and alive pupae in images. The algorithm was based on two methods: 1) noise reduction using mathematical morphology filters, 2) Canny edge detection. The accuracy of the algorithm is higher for the Medipix2 (average recall for detection of alive pupae =0.99, average recall for detection of dead pupae =0.83), than for the flat panel (average recall for detection of alive pupae =0.99, average recall for detection of dead pupae =0.77). Therefore, we conclude that Medipix2 has lower noise and better displays contours (edges) of biological objects. Our method allows automatic selection and calculation of dead and alive chestnut leafminer pupae. It leads to faster monitoring of the population of one of the world's important insect pest.

Fast frame rate rodent cardiac x-ray imaging using scintillator lens coupled to CMOS camera

NASA Astrophysics Data System (ADS)

Swathi Lakshmi, B.; Sai Varsha, M. K. N.; Kumar, N. Ashwin; Dixit, Madhulika; Krishnamurthi, Ganapathy

2017-03-01

Micro-Computed Tomography (MCT) systems for small animal imaging plays a critical role for monitoring disease progression and therapy evaluation. In this work, an in-house built micro-CT system equipped with a X-ray scintillator lens coupled to a commercial CMOS camera was used to test the feasibility of its application to Digital Subtraction Angiography (DSA). Literature has reported such studies being done with clinical X-ray tubes that can be pulsed rapidly or with rotating gantry systems, thus increasing the cost and infrastructural requirements.The feasibility of DSA was evaluated by injected Iodinated contrast agent (ICA) through the tail vein of a mouse. Projection images of the heart were acquired pre and post contrast using the high frame rate X-ray detector and processing done to visualize transit of ICA through the heart.

Convolutional neural networks applied to neutrino events in a liquid argon time projection chamber

DOE PAGES

Acciarri, R.; Adams, C.; An, R.; ...

2017-03-14

Here, we present several studies of convolutional neural networks applied to data coming from the MicroBooNE detector, a liquid argon time projection chamber (LArTPC). The algorithms studied include the classification of single particle images, the localization of single particle and neutrino interactions in an image, and the detection of a simulated neutrino event overlaid with cosmic ray backgrounds taken from real detector data. These studies demonstrate the potential of convolutional neural networks for particle identification or event detection on simulated neutrino interactions. Lastly, we also address technical issues that arise when applying this technique to data from a large LArTPCmore » at or near ground level.« less

Ambient and Cryogenic Alignment Verification and Performance of the Infrared Multi-Object Spectrometer

NASA Technical Reports Server (NTRS)

Connelly, Joseph A.; Ohl, Raymond G.; Mink, Ronald G.; Mentzell, J. Eric; Saha, Timo T.; Tveekrem, June L.; Hylan, Jason E.; Sparr, Leroy M.; Chambers, V. John; Hagopian, John G.

2003-01-01

The Infrared Multi-Object Spectrometer (IRMOS) is a facility instrument for the Kitt Peak National Observatory 4 and 2.1 meter telescopes. IRMOS is a near-IR (0.8 - 2.5 micron) spectrometer with low- to mid-resolving power (R = 300 - 3000). IRMOS produces simultaneous spectra of approximately 100 objects in its 2.8 x 2.0 arc-min field of view using a commercial Micro Electro-Mechanical Systems (MEMS) Digital Micro-mirror Device (DMD) from Texas Instruments. The IRMOS optical design consists of two imaging subsystems. The focal reducer images the focal plane of the telescope onto the DMD field stop, and the spectrograph images the DMD onto the detector. We describe ambient breadboard subsystem alignment and imaging performance of each stage independently, and the ambient and cryogenic imaging performance of the fully assembled instrument. Interferometric measurements of subsystem wavefront error serve to venfy alignment, and are accomplished using a commercial, modified Twyman-Green laser unequal path interferometer. Image testing provides further verification of the optomechanical alignment method and a measurement of near-angle scattered light due to mirror small-scale surface error. Image testing is performed at multiple field points. A mercury-argon pencil lamp provides spectral lines at 546.1 nm and 1550 nm, and a CCD camera and IR camera are used as detectors. We use commercial optical modeling software to predict the point-spread function and its effect on instrument slit transmission and resolution. Our breadboard test results validate this prediction. We conclude with an instrument performance prediction for first light.

Implementation of real-time nonuniformity correction with multiple NUC tables using FPGA in an uncooled imaging system

NASA Astrophysics Data System (ADS)

Oh, Gyong Jin; Kim, Lyang-June; Sheen, Sue-Ho; Koo, Gyou-Phyo; Jin, Sang-Hun; Yeo, Bo-Yeon; Lee, Jong-Ho

2009-05-01

This paper presents a real time implementation of Non Uniformity Correction (NUC). Two point correction and one point correction with shutter were carried out in an uncooled imaging system which will be applied to a missile application. To design a small, light weight and high speed imaging system for a missile system, SoPC (System On a Programmable Chip) which comprises of FPGA and soft core (Micro-blaze) was used. Real time NUC and generation of control signals are implemented using FPGA. Also, three different NUC tables were made to make the operating time shorter and to reduce the power consumption in a large range of environment temperature. The imaging system consists of optics and four electronics boards which are detector interface board, Analog to Digital converter board, Detector signal generation board and Power supply board. To evaluate the imaging system, NETD was measured. The NETD was less than 160mK in three different environment temperatures.

SU-E-I-25: Performance Evaluation of a Proposed CMOS-Based X-Ray Detector Using Linear Cascade Model Analysis.

PubMed

Jain, A; Bednarek, D; Rudin, S

2012-06-01

The need for high-resolution, dynamic x-ray imaging capability for neurovascular applications has put an ever increasing demand on x-ray detector technology. Present state-of-the-art detectors such as flat panels have limited resolution and noise performance. A linear cascade model analysis was used to estimate the theoretical performance for a proposed CMOS-based detector. The proposed CMOS-based detector was assumed to have a 300-micron thick HL type CsI phosphor, 35-micron pixels, a variable gain light image intensifier (LU), and 400 electron readout noise. The proposed detector has a CMOS sensor coupled to an LII which views the output of the CsI phosphor. For the analysis the whole imaging chain was divided into individual stages characterized by one of the basic processes (stochastic/deterministic blurring, binomial selection, quantum gain, additive noise). Standard linear cascade modeling was used for the propagation of signal and noise through the stages and an RQA5 spectrum was assumed. The gain, blurring or transmission of different stages was either measured or taken from manufacturer's specifications. The theoretically calculated MTF and DQE for the proposed detector were compared with a high-resolution, high-sensitive Micro-Angio Fluoroscope (MAF), predecessor of the proposed detector. Signal and noise for each of the 19 stages in the complete imaging chain were calculated and showed improved performance. For example, at 5 cycles/mm the MTF and DQE were 0.08 and 0.28, respectively, for the CMOS detector compared to 0.05 and 0.07 for the MAF detector. The proposed detector will have improved MTF and DQE and slimmer physical dimension due to the elimination of the large fiber-optic taper used in the MAF. Once operational, the proposed CMOS detector will serve as a further improvement over standard flat panel detectors compared to the MAF which is already receiving a very positive reception by neuro-vascular interventionalists. (Support:NIH-Grant R01EB002873) NIH Grants R01- EB008425, R01-EB002873 and an equipment grant from Toshiba Medical Systems Corp. © 2012 American Association of Physicists in Medicine.

Arcsecond and Sub-arcsedond Imaging with X-ray Multi-Image Interferometer and Imager for (very) small sattelites

NASA Astrophysics Data System (ADS)

Hayashida, K.; Kawabata, T.; Nakajima, H.; Inoue, S.; Tsunemi, H.

2017-10-01

The best angular resolution of 0.5 arcsec is realized with the X-ray mirror onborad the Chandra satellite. Nevertheless, further better or comparable resolution is anticipated to be difficult in near future. In fact, the goal of ATHENA telescope is 5 arcsec in the angular resolution. We propose a new type of X-ray interferometer consisting simply of an X-ray absorption grating and an X-ray spectral imaging detector, such as X-ray CCDs or new generation CMOS detectors, by stacking the multi images created with the Talbot interferenece (Hayashida et al. 2016). This system, now we call Multi Image X-ray Interferometer Module (MIXIM) enables arcseconds resolution with very small satellites of 50cm size, and sub-arcseconds resolution with small sattellites. We have performed ground experiments, in which a micro-focus X-ray source, grating with pitch of 4.8μm, and 30 μm pixel detector placed about 1m from the source. We obtained the self-image (interferometirc fringe) of the grating for wide band pass around 10keV. This result corresponds to about 2 arcsec resolution for parrallel beam incidence. The MIXIM is usefull for high angular resolution imaging of relatively bright sources. Search for super massive black holes and resolving AGN torus would be the targets of this system.

SU-D-204-05: Quantitative Comparison of a High Resolution Micro-Angiographic Fluoroscopic (MAF) Detector with a Standard Flat Panel Detector (FPD) Using the New Metric of Generalized Measured Relative Object Detectability (GM-ROD)

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

Russ, M; Ionita, C; Bednarek, D

Purpose: In endovascular image-guided neuro-interventions, visualization of fine detail is paramount. For example, the ability of the interventionist to visualize the stent struts depends heavily on the x-ray imaging detector performance. Methods: A study to examine the relative performance of the high resolution MAF-CMOS (pixel size 75µm, Nyquist frequency 6.6 cycles/mm) and a standard Flat Panel Detector (pixel size 194µm, Nyquist frequency 2.5 cycles/mm) detectors in imaging a neuro stent was done using the Generalized Measured Relative Object Detectability (GM-ROD) metric. Low quantum noise images of a deployed stent were obtained by averaging 95 frames obtained by both detectors withoutmore » changing other exposure or geometric parameters. The square of the Fourier transform of each image is taken and divided by the generalized normalized noise power spectrum to give an effective measured task-specific signal-to-noise ratio. This expression is then integrated from 0 to each of the detector’s Nyquist frequencies, and the GM-ROD value is determined by taking a ratio of the integrals for the MAF-CMOS to that of the FPD. The lower bound of integration can be varied to emphasize high frequencies in the detector comparisons. Results: The MAF-CMOS detector exhibits vastly superior performance over the FPD when integrating over all frequencies, yielding a GM-ROD value of 63.1. The lower bound of integration was stepped up in increments of 0.5 cycles/mm for higher frequency comparisons. As the lower bound increased, the GM-ROD value was augmented, reflecting the superior performance of the MAF-CMOS in the high frequency regime. Conclusion: GM-ROD is a versatile metric that can provide quantitative detector and task dependent comparisons that can be used as a basis for detector selection. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.« less

GEM detector performance with innovative micro-TPC readout in high magnetic field

NASA Astrophysics Data System (ADS)

Garzia, I.; Alexeev, M.; Amoroso, A.; Baldini Ferroli, R.; Bertani, M.; Bettoni, D.; Bianchi, F.; Calcaterra, A.; Canale, N.; Capodiferro, M.; Cassariti, V.; Cerioni, S.; Chai, J. Y.; Chiozzi, S.; Cibinetto, G.; Cossio, F.; Cotta Ramusino, A.; De Mori, F.; Destefanis, M.; Dong, J.; Evangelisti, F.; Evangelisti, F.; Farinelli, R.; Fava, L.; Felici, G.; Fioravanti, E.; Gatta, M.; Greco, M.; Lavezzi, L.; Leng, C. Y.; Li, H.; Maggiora, M.; Malaguti, R.; Marcello, S.; Melchiorri, M.; Mezzadri, G.; Mignone, M.; Morello, G.; Pacetti, S.; Patteri, P.; Pellegrino, J.; Pelosi, A.; Rivetti, A.; Rolo, M. D.; Savrié, M.; Scodeggio, M.; Soldani, E.; Sosio, S.; Spataro, S.; Tskhadadze, E.; Verma, S.; Wheadon, R.; Yan, L.

2018-01-01

Gas detector development is one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detector (MPGD), allowed to overcome several problems related to other types of commonly used detectors, like drift chamber and micro strips detectors, reducing the rate of discharges and providing better radiation tolerance. Among the most used MPGDs are the Gas Electron Multipliers (GEMs). Invented by Sauli in 1997, nowadays GEMs have become an important reality for particle detectors in high energy physics. Commonly deployed as fast timing detectors and triggers, their fast response, high rate capability and high radiation hardness make them also suitable as tracking detectors. The readout scheme is one of the most important features in tracking technology. Analog readout based on the calculation of the center of gravity technique allows to overcome the limit imposed by digital pads, whose spatial resolution is limited by the pitch dimensions. However, the presence of high external magnetic fields can distort the electronic cloud and affect the performance. The development of the micro-TPC reconstruction method brings GEM detectors into a new prospective, improving significantly the spatial resolutionin presence of high magnetic fields. This innovative technique allows to reconstruct the 3-dimensional particle position, as Time Projection Chamber, but within a drift gap of a few millimeters. In these report, the charge centroid and micro-TPC methods are described in details. We discuss the results of several test beams performed with planar chambers in magnetic field. These results are one of the first developments of micro-TPC technique for GEM detectors, which allows to reach unprecedented performance in a high magnetic field of 1 T.

Design, construction, and evaluation of new high resolution medical imaging detector/systems

NASA Astrophysics Data System (ADS)

Jain, Amit

Increasing need of minimally invasive endovascular image guided interventional procedures (EIGI) for accurate and successful treatment of vascular disease has set a quest for better image quality. Current state of the art detectors are not up to the mark for these complex procedures due to their inherent limitations. Our group has been actively working on the design and construction of a high resolution, region of interest CCD-based X-ray imager for some time. As a part of that endeavor, a Micro-angiographic fluoroscope (MAF) was developed to serve as a high resolution, ROI X-ray imaging detector in conjunction with large lower resolution full field of view (FOV) state-of-the-art x-ray detectors. The newly developed MAF is an indirect x-ray imaging detector capable of providing real-time images with high resolution, high sensitivity, no lag and low instrumentation noise. It consists of a CCD camera coupled to a light image intensifier (LII) through a fiber optic taper. The CsI(Tl) phosphor serving as the front end is coupled to the LII. For this work, the MAF was designed and constructed. The linear system cascade theory was used to evaluate the performance theoretically. Linear system metrics such as MTF and DQE were used to gauge the detector performance experimentally. The capabilities of the MAF as a complete system were tested using generalized linear system metrics. With generalized linear system metrics the effects of finite size focal spot, geometric magnification and the presence of scatter are included in the analysis and study. To minimize the effect of scatter, an anti-scatter grid specially designed for the MAF was also studied. The MAF was compared with the flat panel detector using signal-to-noise ratio and the two dimensional linear system metrics. The signal-to-noise comparison was carried out to point out the effect of pixel size and Point Spread Function of the detector. The two dimensional linear system metrics were used to investigate the comparative performance of both the detectors in similar simulated clinical neuro-vascular conditions. The last part of this work presents a unique quality of the MAF: operation in single photon mode. The successful operation of the MAF was demonstrated with considerable improvement in spatial and contrast resolution over conventional energy integrating mode. The work presented shows the evolution of a high resolution, high sensitivity, and region of interest x-ray imaging detector as an attractive and capable x-ray imager for the betterment of complex EIGI procedures. The capability of single photon counting mode imaging provides the potential for additional uses of the MAF including the possibility of use in dual modality imaging with radionuclide sources as well as x-rays.

Micro-machined thermo-conductivity detector

DOEpatents

Yu, Conrad

2003-01-01

A micro-machined thermal conductivity detector for a portable gas chromatograph. The detector is highly sensitive and has fast response time to enable detection of the small size gas samples in a portable gas chromatograph which are in the order of nanoliters. The high sensitivity and fast response time are achieved through micro-machined devices composed of a nickel wire, for example, on a silicon nitride window formed in a silicon member and about a millimeter square in size. In addition to operating as a thermal conductivity detector, the silicon nitride window with a micro-machined wire therein of the device can be utilized for a fast response heater for PCR applications.

Bolometric detectors for the high frequency instrument on the Planck surveyor

NASA Technical Reports Server (NTRS)

Koch, T. C.; Paine, C.; Husted, L.; Yun, M.; Lange, A.; Bock, J.; Jones, B.; Ade, P.; Sudiwala, R.

2002-01-01

The High Frequency Instrument (HFI) on Planck will obtain all-sky images of the Cosmic Microwave Background (CMB) and other astrophysical sources of emission with resolution of 9 arcniin at 100 GHz, 7 arcmin at 143 GHz and 5 arcniin at 217, 353, 545 and 857 GHz. The HFI focal plane will contain 48 silicon nitride micromesh bolometric detectors operating from a 100 mK heat sink. Four detectors in each of the 6 bands will detect the sum of the power in both linear polarizations. An additional 4 pair of detectors will provide sensitivity to linear polarization of emission at 143, 217 and 353 GHz. We report on the development of these detectors, which are being produced at the JPL Micro Devices Laboratory, packaged at JPL Electronics Packaging, characterized at 100 mK before delivery to our HFI consortium partners at the UWCC, UK.

Initial studies using the RatCAP conscious animal PET tomograph

NASA Astrophysics Data System (ADS)

Woody, C.; Vaska, P.; Schlyer, D.; Pratte, J.-F.; Junnarkar, S.; Park, S.-J.; Stoll, S.; Purschke, M.; Southekal, S.; Kriplani, A.; Krishnamoorthy, S.; Maramraju, S.; Lee, D.; Schiffer, W.; Dewey, S.; Neill, J.; Kandasamy, A.; O'Connor, P.; Radeka, V.; Fontaine, R.; Lecomte, R.

2007-02-01

The RatCAP is a small, head-mounted PET tomograph designed to image the brain of a conscious rat without the use of anesthesia. The detector is a complete, high-performance 3D tomograph consisting of a 3.8 cm inside-diameter ring containing 12 block detectors, each of which is comprised of a 4×8 array of 2.2×2.2×5 mm 3 LSO crystals readout with a matching APD array and custom ASIC, and has a 1.8 cm axial field of view. Construction of the first working prototype detector has been completed and its performance characteristics have been measured. The results show an intrinsic spatial resolution of 2.1 mm, a time resolution of ˜14 ns FWHM, and a sensitivity of 0.7% at an energy threshold of 150 keV. First preliminary images have been obtained using 18F-FDG and 11C-methamphetamine, which show comparable image quality to those obtained from a commercial MicroPET R4 scanner. Initial studies have also been carried out to study stress levels in rats wearing the RatCAP.

Spectroscopic micro-tomography of metallic-organic composites by means of photon-counting detectors

NASA Astrophysics Data System (ADS)

Pichotka, M.; Jakubek, J.; Vavrik, D.

2015-12-01

The presumed capabilities of photon counting detectors have aroused major expectations in several fields of research. In the field of nuclear imaging ample benefits over standard detectors are to be expected from photon counting devices. First of all a very high contrast, as has by now been verified in numerous experiments. The spectroscopic capabilities of photon counting detectors further allow material decomposition in computed tomography and therefore inherently adequate beam hardening correction. For these reasons measurement setups featuring standard X-ray tubes combined with photon counting detectors constitute a possible replacement of the much more cost intensive tomographic setups at synchrotron light-sources. The actual application of photon counting detectors in radiographic setups in recent years has been impeded by a number of practical issues, above all by restrictions in the detectors size. Currently two tomographic setups in Czech Republic feature photon counting large-area detectors (LAD) fabricated in Prague. The employed large area hybrid pixel-detector assemblies [1] consisting of 10×10/10×5 Timepix devices have a surface area of 143×143 mm2 / 143×71,5 mm2 respectively, suitable for micro-tomographic applications. In the near future LAD devices featuring the Medipix3 readout chip as well as heavy sensors (CdTe, GaAs) will become available. Data analysis is obtained by a number of in house software tools including iterative multi-energy volume reconstruction.In this paper tomographic analysis of of metallic-organic composites is employed to illustrate the capabilities of our technology. Other than successful material decomposition by spectroscopic tomography we present a method to suppress metal artefacts under certain conditions.

The Pandora multi-algorithm approach to automated pattern recognition of cosmic-ray muon and neutrino events in the MicroBooNE detector

NASA Astrophysics Data System (ADS)

Acciarri, R.; Adams, C.; An, R.; Anthony, J.; Asaadi, J.; Auger, M.; Bagby, L.; Balasubramanian, S.; Baller, B.; Barnes, C.; Barr, G.; Bass, M.; Bay, F.; Bishai, M.; Blake, A.; Bolton, T.; Camilleri, L.; Caratelli, D.; Carls, B.; Castillo Fernandez, R.; Cavanna, F.; Chen, H.; Church, E.; Cianci, D.; Cohen, E.; Collin, G. H.; Conrad, J. M.; Convery, M.; Crespo-Anadón, J. I.; Del Tutto, M.; Devitt, D.; Dytman, S.; Eberly, B.; Ereditato, A.; Escudero Sanchez, L.; Esquivel, J.; Fadeeva, A. A.; Fleming, B. T.; Foreman, W.; Furmanski, A. P.; Garcia-Gamez, D.; Garvey, G. T.; Genty, V.; Goeldi, D.; Gollapinni, S.; Graf, N.; Gramellini, E.; Greenlee, H.; Grosso, R.; Guenette, R.; Hackenburg, A.; Hamilton, P.; Hen, O.; Hewes, J.; Hill, C.; Ho, J.; Horton-Smith, G.; Hourlier, A.; Huang, E.-C.; James, C.; Jan de Vries, J.; Jen, C.-M.; Jiang, L.; Johnson, R. A.; Joshi, J.; Jostlein, H.; Kaleko, D.; Karagiorgi, G.; Ketchum, W.; Kirby, B.; Kirby, M.; Kobilarcik, T.; Kreslo, I.; Laube, A.; Li, Y.; Lister, A.; Littlejohn, B. R.; Lockwitz, S.; Lorca, D.; Louis, W. C.; Luethi, M.; Lundberg, B.; Luo, X.; Marchionni, A.; Mariani, C.; Marshall, J.; Martinez Caicedo, D. A.; Meddage, V.; Miceli, T.; Mills, G. B.; Moon, J.; Mooney, M.; Moore, C. D.; Mousseau, J.; Murrells, R.; Naples, D.; Nienaber, P.; Nowak, J.; Palamara, O.; Paolone, V.; Papavassiliou, V.; Pate, S. F.; Pavlovic, Z.; Piasetzky, E.; Porzio, D.; Pulliam, G.; Qian, X.; Raaf, J. L.; Rafique, A.; Rochester, L.; Rudolf von Rohr, C.; Russell, B.; Schmitz, D. W.; Schukraft, A.; Seligman, W.; Shaevitz, M. H.; Sinclair, J.; Smith, A.; Snider, E. L.; Soderberg, M.; Söldner-Rembold, S.; Soleti, S. R.; Spentzouris, P.; Spitz, J.; St. John, J.; Strauss, T.; Szelc, A. M.; Tagg, N.; Terao, K.; Thomson, M.; Toups, M.; Tsai, Y.-T.; Tufanli, S.; Usher, T.; Van De Pontseele, W.; Van de Water, R. G.; Viren, B.; Weber, M.; Wickremasinghe, D. A.; Wolbers, S.; Wongjirad, T.; Woodruff, K.; Yang, T.; Yates, L.; Zeller, G. P.; Zennamo, J.; Zhang, C.

2018-01-01

The development and operation of liquid-argon time-projection chambers for neutrino physics has created a need for new approaches to pattern recognition in order to fully exploit the imaging capabilities offered by this technology. Whereas the human brain can excel at identifying features in the recorded events, it is a significant challenge to develop an automated, algorithmic solution. The Pandora Software Development Kit provides functionality to aid the design and implementation of pattern-recognition algorithms. It promotes the use of a multi-algorithm approach to pattern recognition, in which individual algorithms each address a specific task in a particular topology. Many tens of algorithms then carefully build up a picture of the event and, together, provide a robust automated pattern-recognition solution. This paper describes details of the chain of over one hundred Pandora algorithms and tools used to reconstruct cosmic-ray muon and neutrino events in the MicroBooNE detector. Metrics that assess the current pattern-recognition performance are presented for simulated MicroBooNE events, using a selection of final-state event topologies.

Simultaneous determination of chlorinated organic compounds from environmental samples using gas chromatography coupled with a micro electron capture detector and micro-plasma atomic emission detector

NASA Astrophysics Data System (ADS)

Quan, Xie; Chen, Shuo; Platzer, Bernhard; Chen, Jingwen; Gfrerer, Marion

2002-01-01

Water and sediment samples were screened simultaneously for the presence of polychlorinated organic compounds using gas chromatography (GC) coupled with an micro electron capture detector (μ-ECD) and a newly developed helium plasma based on a micro-atomic emission detector (μ-AED). The GC column effluent was split 15:85 between two detectors. In this way, two chromatograms, one obtained by μ-ECD and another by μ-AED, were recorded simultaneously. α-, β-hexachlorocyclohexane and p, p'-DDE were detected. RSDs of the monitoring results from the two detection methods were <20% for the three compounds. A detection limit of 8.5 pg and at least 3 orders of magnitude of linear range for μ-AED was observed.

Large area silicon drift detectors for x-rays -- New results

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

Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.

Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range 75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detectormore » response over the entire active area (measured using 560 nm light) was < 0.5%.« less

Simulations of a micro-PET system based on liquid xenon

NASA Astrophysics Data System (ADS)

Miceli, A.; Glister, J.; Andreyev, A.; Bryman, D.; Kurchaninov, L.; Lu, P.; Muennich, A.; Retiere, F.; Sossi, V.

2012-03-01

The imaging performance of a high-resolution preclinical micro-positron emission tomography (micro-PET) system employing liquid xenon (LXe) as the gamma-ray detection medium was simulated. The arrangement comprises a ring of detectors consisting of trapezoidal LXe time projection ionization chambers and two arrays of large area avalanche photodiodes for the measurement of ionization charge and scintillation light. A key feature of the LXePET system is the ability to identify individual photon interactions with high energy resolution and high spatial resolution in three dimensions and determine the correct interaction sequence using Compton reconstruction algorithms. The simulated LXePET imaging performance was evaluated by computing the noise equivalent count rate, the sensitivity and point spread function for a point source according to the NEMA-NU4 standard. The image quality was studied with a micro-Derenzo phantom. Results of these simulation studies included noise equivalent count rate peaking at 1326 kcps at 188 MBq (705 kcps at 184 MBq) for an energy window of 450-600 keV and a coincidence window of 1 ns for mouse (rat) phantoms. The absolute sensitivity at the center of the field of view was 12.6%. Radial, tangential and axial resolutions of 22Na point sources reconstructed with a list-mode maximum likelihood expectation maximization algorithm were ⩽0.8 mm (full-width at half-maximum) throughout the field of view. Hot-rod inserts of <0.8 mm diameter were resolvable in the transaxial image of a micro-Derenzo phantom. The simulations show that a LXe system would provide new capabilities for significantly enhancing PET images.

LabVIEW Graphical User Interface for a New High Sensitivity, High Resolution Micro-Angio-Fluoroscopic and ROI-CBCT System

PubMed Central

Keleshis, C; Ionita, CN; Yadava, G; Patel, V; Bednarek, DR; Hoffmann, KR; Verevkin, A; Rudin, S

2008-01-01

A graphical user interface based on LabVIEW software was developed to enable clinical evaluation of a new High-Sensitivity Micro-Angio-Fluoroscopic (HSMAF) system for real-time acquisition, display and rapid frame transfer of high-resolution region-of-interest images. The HSMAF detector consists of a CsI(Tl) phosphor, a light image intensifier (LII), and a fiber-optic taper coupled to a progressive scan, frame-transfer, charged-coupled device (CCD) camera which provides real-time 12 bit, 1k × 1k images capable of greater than 10 lp/mm resolution. Images can be captured in continuous or triggered mode, and the camera can be programmed by a computer using Camera Link serial communication. A graphical user interface was developed to control the camera modes such as gain and pixel binning as well as to acquire, store, display, and process the images. The program, written in LabVIEW, has the following capabilities: camera initialization, synchronized image acquisition with the x-ray pulses, roadmap and digital subtraction angiography acquisition (DSA), flat field correction, brightness and contrast control, last frame hold in fluoroscopy, looped playback of the acquired images in angiography, recursive temporal filtering and LII gain control. Frame rates can be up to 30 fps in full-resolution mode. The user friendly implementation of the interface along with the high framerate acquisition and display for this unique high-resolution detector should provide angiographers and interventionalists with a new capability for visualizing details of small vessels and endovascular devices such as stents and hence enable more accurate diagnoses and image guided interventions. (Support: NIH Grants R01NS43924, R01EB002873) PMID:18836570

LabVIEW Graphical User Interface for a New High Sensitivity, High Resolution Micro-Angio-Fluoroscopic and ROI-CBCT System.

PubMed

Keleshis, C; Ionita, Cn; Yadava, G; Patel, V; Bednarek, Dr; Hoffmann, Kr; Verevkin, A; Rudin, S

2008-01-01

A graphical user interface based on LabVIEW software was developed to enable clinical evaluation of a new High-Sensitivity Micro-Angio-Fluoroscopic (HSMAF) system for real-time acquisition, display and rapid frame transfer of high-resolution region-of-interest images. The HSMAF detector consists of a CsI(Tl) phosphor, a light image intensifier (LII), and a fiber-optic taper coupled to a progressive scan, frame-transfer, charged-coupled device (CCD) camera which provides real-time 12 bit, 1k × 1k images capable of greater than 10 lp/mm resolution. Images can be captured in continuous or triggered mode, and the camera can be programmed by a computer using Camera Link serial communication. A graphical user interface was developed to control the camera modes such as gain and pixel binning as well as to acquire, store, display, and process the images. The program, written in LabVIEW, has the following capabilities: camera initialization, synchronized image acquisition with the x-ray pulses, roadmap and digital subtraction angiography acquisition (DSA), flat field correction, brightness and contrast control, last frame hold in fluoroscopy, looped playback of the acquired images in angiography, recursive temporal filtering and LII gain control. Frame rates can be up to 30 fps in full-resolution mode. The user friendly implementation of the interface along with the high framerate acquisition and display for this unique high-resolution detector should provide angiographers and interventionalists with a new capability for visualizing details of small vessels and endovascular devices such as stents and hence enable more accurate diagnoses and image guided interventions. (Support: NIH Grants R01NS43924, R01EB002873).

MicroBooNE Detector Move

ScienceCinema

Flemming, Bonnie; Rameika, Gina

2018-05-18

On Monday, June 23, 2014 the MicroBooNE detector -- a 30-ton vessel that will be used to study ghostly particles called neutrinos -- was transported three miles across the Fermilab site and gently lowered into the laboratory's Liquid-Argon Test Facility. This video documents that move, some taken with time-lapse camerad, and shows the process of getting the MicroBooNE detector to its new home.

Advantages of phase retrieval for fast x-ray tomographic microscopy

NASA Astrophysics Data System (ADS)

Mokso, R.; Marone, F.; Irvine, S.; Nyvlt, M.; Schwyn, D.; Mader, K.; Taylor, G. K.; Krapp, H. G.; Skeren, M.; Stampanoni, M.

2013-12-01

In near-field imaging with partially coherent x-rays, the phase shifting properties of the sample are encoded in the diffraction fringes that appear as an additional intensity modulation in the x-ray projection images. These Fresnel fringes are often regarded as purely an enhancement of the visibility at the interfaces. We show that retrieving the phase information contained in these patterns significantly advances the developments in fast micro-tomography. Improving temporal resolution without intensifying radiation damage implies a shortening of the exposure time rather than increasing the photon flux on the sample. Phase retrieval, to a large extent, compensates the consequent photon count moderation in the images, by fully exploiting the stronger refraction effect as compared with absorption. Two single-distance phase retrieval methods are evaluated for the case of an in situ 3 Hz micro-tomography of a rapidly evolving liquid foam, and an in vivo 6 Hz micro-tomography of a blowfly. A new dual-detector setup is introduced for simultaneous acquisition of two near-field diffraction patterns. Our goal is to couple high temporal, spatial and density resolution in a single imaging system in a dose-efficient manner, opening further options for dynamic four-dimensional studies.

Sub-micro-liter Electrochemical Single-Nucleotide-Polymorphism Detector for Lab-on-a-Chip System

NASA Astrophysics Data System (ADS)

Tanaka, Hiroyuki; Fiorini, Paolo; Peeters, Sara; Majeed, Bivragh; Sterken, Tom; de Beeck, Maaike Op; Hayashi, Miho; Yaku, Hidenobu; Yamashita, Ichiro

2012-04-01

A sub-micro-liter single-nucleotide-polymorphism (SNP) detector for lab-on-a-chip applications is developed. This detector enables a fast, sensitive, and selective SNP detection directly from human blood. The detector is fabricated on a Si substrate by a standard complementary metal oxide semiconductor/micro electro mechanical systems (CMOS/MEMS) process and Polydimethylsiloxane (PDMS) molding. Stable and reproducible measurements are obtained by implementing an on-chip Ag/AgCl electrode and encapsulating the detector. The detector senses the presence of SNPs by measuring the concentration of pyrophosphoric acid generated during selective DNA amplification. A 0.5-µL-volume detector enabled the successful performance of the typing of a SNP within the ABO gene using human blood. The measured sensitivity is 566 pA/µM.

Large area silicon drift detectors for x-rays -- New results

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

Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.

Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range {minus}75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detectormore » response over the entire active area (measured using 560 nm light) was <0.5%.« less

Reconstructing Michel Electrons in the MicroBooNE Detector

NASA Astrophysics Data System (ADS)

Caratelli, David

2016-03-01

MicroBooNE is a Liquid Argon Time Projection Chamber (LArTPC) neutrino detector located in the Booster Neutrino Beamline at Fermilab which began collecting neutrino data in October 2015. MicroBooNE aims to explore the low-energy excess in the νe spectrum reported by MiniBooNE as well as perform ν-Ar cross-section measurements. In this talk, we present the current status of reconstructing Michel electrons from cosmic ray muons in the MicroBooNE detector. These Michel electrons are distributed uniformly inside the detector, and serve as a natural and powerful calibration source to study the detector's response for low energy (10s of MeV) interactions as a function of position. We have developed a reconstruction software tool to successfully identify such Michel electrons which could be of benefit to LArTPC experiments generically.

Atomic force microscope based on vertical silicon probes

NASA Astrophysics Data System (ADS)

Walter, Benjamin; Mairiaux, Estelle; Faucher, Marc

2017-06-01

A family of silicon micro-sensors for Atomic Force Microscope (AFM) is presented that allows to operate with integrated transducers from medium to high frequencies together with moderate stiffness constants. The sensors are based on Micro-Electro-Mechanical-Systems technology. The vertical design specifically enables a long tip to oscillate perpendicularly to the surface to be imaged. The tip is part of a resonator including quasi-flexural composite beams, and symmetrical transducers that can be used as piezoresistive detector and/or electro-thermal actuator. Two vertical probes (Vprobes) were operated up to 4.3 MHz with stiffness constants 150 N/m to 500 N/m and the capability to oscillate from 10 pm to 90 nm. AFM images of several samples both in amplitude modulation (tapping-mode) and in frequency modulation were obtained.

Alignment and Performance of the Infrared Multi-Object Spectrometer

NASA Technical Reports Server (NTRS)

Connelly, Joseph A.; Ohl, Raymond G.; Mentzell, J. Eric; Madison, Timothy J.; Hylan, Jason E.; Mink, Ronald G.; Saha, Timo T.; Tveekrem, June L.; Sparr, Leroy M.; Chambers, V. John;

Multicenter evaluation of a synthetic single-crystal diamond detector for CyberKnife small field size output factors.

PubMed

Russo, Serenella; Masi, Laura; Francescon, Paolo; Frassanito, Maria Cristina; Fumagalli, Maria Luisa; Marinelli, Marco; Falco, Maria Daniela; Martinotti, Anna Stefania; Pimpinella, Maria; Reggiori, Giacomo; Verona Rinati, Gianluca; Vigorito, Sabrina; Mancosu, Pietro

2016-04-01

The aim of the present work was to evaluate small field size output factors (OFs) using the latest diamond detector commercially available, PTW-60019 microDiamond, over different CyberKnife systems. OFs were measured also by silicon detectors routinely used by each center, considered as reference. Five Italian CyberKnife centers performed OFs measurements for field sizes ranging from 5 to 60mm, defined by fixed circular collimators (5 centers) and by Iris(™) variable aperture collimator (4 centers). Setup conditions were: 80cm source to detector distance, and 1.5cm depth in water. To speed up measurements two diamond detectors were used and their equivalence was evaluated. MonteCarlo (MC) correction factors for silicon detectors were used for comparing the OF measurements. Considering OFs values averaged over all centers, diamond data resulted lower than uncorrected silicon diode ones. The agreement between diamond and MC corrected silicon values was within 0.6% for all fixed circular collimators. Relative differences between microDiamond and MC corrected silicon diodes data for Iris(™) collimator were lower than 1.0% for all apertures in the totality of centers. The two microDiamond detectors showed similar characteristics, in agreement with the technical specifications. Excellent agreement between microDiamond and MC corrected silicon diode detectors OFs was obtained for both collimation systems fixed cones and Iris(™), demonstrating the microDiamond could be a suitable detector for CyberKnife commissioning and routine checks. These results obtained in five centers suggest that for CyberKnife systems microDiamond can be used without corrections even at the smallest field size. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Terahertz holography for imaging amplitude and phase objects.

PubMed

Hack, Erwin; Zolliker, Peter

2014-06-30

A non-monochromatic THz Quantum Cascade Laser and an uncooled micro-bolometer array detector with VGA resolution are used in a beam-splitter free holographic set-up to measure amplitude and phase objects in transmission. Phase maps of the diffraction pattern are retrieved using the Fourier transform carrier fringe method; while a Fresnel-Kirchhoff back propagation algorithm is used to reconstruct the complex object image. A lateral resolution of 280 µm and a relative phase sensitivity of about 0.5 rad are estimated from reconstructed images of a metallic Siemens star and a polypropylene test structure, respectively. Simulations corroborate the experimental results.

Time-of-flight camera via a single-pixel correlation image sensor

NASA Astrophysics Data System (ADS)

Mao, Tianyi; Chen, Qian; He, Weiji; Dai, Huidong; Ye, Ling; Gu, Guohua

2018-04-01

A time-of-flight imager based on single-pixel correlation image sensors is proposed for noise-free depth map acquisition in presence of ambient light. Digital micro-mirror device and time-modulated IR-laser provide spatial and temporal illumination on the unknown object. Compressed sensing and ‘four bucket principle’ method are combined to reconstruct the depth map from a sequence of measurements at a low sampling rate. Second-order correlation transform is also introduced to reduce the noise from the detector itself and direct ambient light. Computer simulations are presented to validate the computational models and improvement of reconstructions.

Study on a two-dimensional scanning micro-mirror and its application in a MOEMS target detector.

PubMed

Zhang, Chi; You, Zheng; Huang, Hu; Li, Guanhua

2010-01-01

A two-dimensional (2D) scanning micro-mirror for target detection and measurement has been developed. This new micro-mirror is used in a MOEMS target detector to replace the conventional scanning detector. The micro-mirror is fabricated by MEMS process and actuated by a piezoelectric actuator. To achieve large deflection angles, the micro-mirror is excited in the resonance modes. It has two degrees of freedom and changes the direction of the emitted laser beam for a regional 2D scanning. For the deflection angles measurement, piezoresistors are integrated in the micro-mirror and the deflection angles of each direction can be detected independently and precisely. Based on the scanning micro-mirror and the phase-shift ranging technology, a MOEMS target detector has been developed in a size of 90 mm × 35 mm × 50 mm. The experiment shows that the target can be detected in the scanning field and the relative range and orientation can be measured by the MOEMS target detector. For the target distance up to 3 m with a field of view about 20° × 20°, the measurement resolution is about 10.2 cm in range, 0.15° in the horizontal direction and 0.22° in the vertical direction for orientation.

Study on a Two-Dimensional Scanning Micro-Mirror and Its Application in a MOEMS Target Detector

PubMed Central

Zhang, Chi; You, Zheng; Huang, Hu; Li, Guanhua

2010-01-01

A two-dimensional (2D) scanning micro-mirror for target detection and measurement has been developed. This new micro-mirror is used in a MOEMS target detector to replace the conventional scanning detector. The micro-mirror is fabricated by MEMS process and actuated by a piezoelectric actuator. To achieve large deflection angles, the micro-mirror is excited in the resonance modes. It has two degrees of freedom and changes the direction of the emitted laser beam for a regional 2D scanning. For the deflection angles measurement, piezoresistors are integrated in the micro-mirror and the deflection angles of each direction can be detected independently and precisely. Based on the scanning micro-mirror and the phase-shift ranging technology, a MOEMS target detector has been developed in a size of 90 mm × 35 mm × 50 mm. The experiment shows that the target can be detected in the scanning field and the relative range and orientation can be measured by the MOEMS target detector. For the target distance up to 3 m with a field of view about 20° × 20°, the measurement resolution is about 10.2 cm in range, 0.15° in the horizontal direction and 0.22° in the vertical direction for orientation. PMID:22163580

Automatic detection of recoil-proton tracks and background rejection criteria in liquid scintillator-micro-capillary-array fast neutron spectrometer

NASA Astrophysics Data System (ADS)

Mor, Ilan; Vartsky, David; Dangendorf, Volker; Tittelmeier, Kai.; Weierganz, Mathias; Goldberg, Mark Benjamin; Bar, Doron; Brandis, Michal

2018-06-01

We describe an analysis procedure for automatic unambiguous detection of fast-neutron-induced recoil proton tracks in a micro-capillary array filled with organic liquid scintillator. The detector is viewed by an intensified CCD camera. This imaging neutron detector possesses the capability to perform high position-resolution (few tens of μm), energy-dispersive transmission-imaging using ns-pulsed beams. However, when operated with CW or DC beams, it also features medium-quality spectroscopic capabilities for incident neutrons in the energy range 2-20 MeV. In addition to the recoil proton events which display a continuous extended track structure, the raw images exhibit complex ion-tracks from nuclear interactions of fast-neutrons in the scintillator, capillaries quartz-matrix and CCD. Moreover, as expected, one also observes a multitude of isolated scintillation spots of varying intensity (henceforth denoted "blobs") that originate from several different sources, such as: fragmented proton tracks, gamma-rays, heavy-ion reactions as well as events and noise that occur in the image-intensifier and CCD. In order to identify the continuous-track recoil proton events and distinguish them from all these background events, a rapid, computerized and automatic track-recognition-procedure was developed. Based on an appropriately weighted analysis of track parameters such as: length, width, area and overall light intensity, the method is capable of distinguishing a single continuous-track recoil proton from typically surrounding several thousands of background events that are found in each CCD frame.

The role of a microDiamond detector in the dosimetry of proton pencil beams.

PubMed

Gomà, Carles; Marinelli, Marco; Safai, Sairos; Verona-Rinati, Gianluca; Würfel, Jan

2016-03-01

In this work, the performance of a microDiamond detector in a scanned proton beam is studied and its potential role in the dosimetric characterization of proton pencil beams is assessed. The linearity of the detector response with the absorbed dose and the dependence on the dose-rate were tested. The depth-dose curve and the lateral dose profiles of a proton pencil beam were measured and compared to reference data. The feasibility of calibrating the beam monitor chamber with a microDiamond detector was also studied. It was found the detector reading is linear with the absorbed dose to water (down to few cGy) and the detector response is independent of both the dose-rate (up to few Gy/s) and the proton beam energy (within the whole clinically-relevant energy range). The detector showed a good performance in depth-dose curve and lateral dose profile measurements; and it might even be used to calibrate the beam monitor chambers-provided it is cross-calibrated against a reference ionization chamber. In conclusion, the microDiamond detector was proved capable of performing an accurate dosimetric characterization of proton pencil beams. Copyright © 2015. Published by Elsevier GmbH.

Dosimetric characterization of a microDiamond detector in clinical scanned carbon ion beams.

PubMed

Marinelli, Marco; Prestopino, G; Verona, C; Verona-Rinati, G; Ciocca, M; Mirandola, A; Mairani, A; Raffaele, L; Magro, G

2015-04-01

To investigate for the first time the dosimetric properties of a new commercial synthetic diamond detector (PTW microDiamond) in high-energy scanned clinical carbon ion beams generated by a synchrotron at the CNAO facility. The detector response was evaluated in a water phantom with actively scanned carbon ion beams ranging from 115 to 380 MeV/u (30-250 mm Bragg peak depth in water). Homogeneous square fields of 3 × 3 and 6 × 6 cm(2) were used. Short- and medium-term (2 months) detector response stability, dependence on beam energy as well as ion type (carbon ions and protons), linearity with dose, and directional and dose-rate dependence were investigated. The depth dose curve of a 280 MeV/u carbon ion beam, scanned over a 3 × 3 cm(2) area, was measured with the microDiamond detector and compared to that measured using a PTW Advanced Markus ionization chamber, and also simulated using fluka Monte Carlo code. The detector response in two spread-out-Bragg-peaks (SOBPs), respectively, centered at 9 and 21 cm depths in water and calculated using the treatment planning system (TPS) used at CNAO, was measured. A negligible drift of detector sensitivity within the experimental session was seen, indicating that no detector preirradiation was needed. Short-term response reproducibility around 1% (1 standard deviation) was found. Only 2% maximum variation of microDiamond sensitivity was observed among all the evaluated proton and carbon ion beam energies. The detector response showed a good linear behavior. Detector sensitivity was found to be dose-rate independent, with a variation below 1.3% in the evaluated dose-rate range. A very good agreement between measured and simulated Bragg curves with both microDiamond and Advanced Markus chamber was found, showing a negligible LET dependence of the tested detector. A depth dose curve was also measured by positioning the microDiamond with its main axis oriented orthogonally to the beam direction. A strong distortion in Bragg peak measurement was observed, confirming manufacturer recommendation on avoiding such configuration. Very good results were obtained for SOBP measurements, with a difference below 1% between measured and TPS-calculated doses. The stability of detector sensitivity in the observation period was within the experimental uncertainty. Dosimetric characterization of a PTW microDiamond detector in high-energy scanned carbon ion beams was performed. The results of the present study showed that this detector is suitable for dosimetry of clinical carbon ion beams, with a negligible LET and dose-rate dependence.

Geometric correction methods for Timepix based large area detectors

NASA Astrophysics Data System (ADS)

Zemlicka, J.; Dudak, J.; Karch, J.; Krejci, F.

2017-01-01

X-ray micro radiography with the hybrid pixel detectors provides versatile tool for the object inspection in various fields of science. It has proven itself especially suitable for the samples with low intrinsic attenuation contrast (e.g. soft tissue in biology, plastics in material sciences, thin paint layers in cultural heritage, etc.). The limited size of single Medipix type detector (1.96 cm2) was recently overcome by the construction of large area detectors WidePIX assembled of Timepix chips equipped with edgeless silicon sensors. The largest already built device consists of 100 chips and provides fully sensitive area of 14.3 × 14.3 cm2 without any physical gaps between sensors. The pixel resolution of this device is 2560 × 2560 pixels (6.5 Mpix). The unique modular detector layout requires special processing of acquired data to avoid occurring image distortions. It is necessary to use several geometric compensations after standard corrections methods typical for this type of pixel detectors (i.e. flat-field, beam hardening correction). The proposed geometric compensations cover both concept features and particular detector assembly misalignment of individual chip rows of large area detectors based on Timepix assemblies. The former deals with larger border pixels in individual edgeless sensors and their behaviour while the latter grapple with shifts, tilts and steps between detector rows. The real position of all pixels is defined in Cartesian coordinate system and together with non-binary reliability mask it is used for the final image interpolation. The results of geometric corrections for test wire phantoms and paleo botanic material are presented in this article.

Upconversion single-microbelt photodetector via two-photon absorption simultaneous

NASA Astrophysics Data System (ADS)

Lou, Guanlin; Wu, Yanyan; Zhu, Hai; Li, Jinyu; Chen, Anqi; Chen, Zhiyang; Liang, Yunfeng; Ren, Yuhao; Gui, Xuchun; Zhong, Dingyong; Qiu, Zhiren; Tang, Zikang; Su, Shi C.

2018-05-01

Single microbelt (MB) photodetectors with metal–semiconductor-metal structure have been demonstrated and characterized comprehensively. For single-photon absorption, the maximum responsivity of ZnO-MB photodetector can reach as high as 1.4  ×  105 A W‑1 at 20 V bias. The results about photoresponse of MB-detector reveals that two relaxation mechanisms contribute to the carrier decay time. Moreover, the two-photon absorption upconversion photoresponsivity in the single-MB detector has also been realized, which is the first report about the two-photon absorption detector to the best of our knowledge. The excellent two-photon absorption photoresponsivity characteristic of the MB device can be available not only for detector but also for solar cell and biomedical imaging. The above results present a significant step towards future fabrication of single micro/nano-structure based multiphoton excitation optoelectronic devices.

Novel instrumentation of multispectral imaging technology for detecting tissue abnormity

NASA Astrophysics Data System (ADS)

Yi, Dingrong; Kong, Linghua

2012-10-01

Multispectral imaging is becoming a powerful tool in a wide range of biological and clinical studies by adding spectral, spatial and temporal dimensions to visualize tissue abnormity and the underlying biological processes. A conventional spectral imaging system includes two physically separated major components: a band-passing selection device (such as liquid crystal tunable filter and diffraction grating) and a scientific-grade monochromatic camera, and is expensive and bulky. Recently micro-arrayed narrow-band optical mosaic filter was invented and successfully fabricated to reduce the size and cost of multispectral imaging devices in order to meet the clinical requirement for medical diagnostic imaging applications. However the challenging issue of how to integrate and place the micro filter mosaic chip to the targeting focal plane, i.e., the imaging sensor, of an off-shelf CMOS/CCD camera is not reported anywhere. This paper presents the methods and results of integrating such a miniaturized filter with off-shelf CMOS imaging sensors to produce handheld real-time multispectral imaging devices for the application of early stage pressure ulcer (ESPU) detection. Unlike conventional multispectral imaging devices which are bulky and expensive, the resulting handheld real-time multispectral ESPU detector can produce multiple images at different center wavelengths with a single shot, therefore eliminates the image registration procedure required by traditional multispectral imaging technologies.

Isometric multimodal photoacoustic microscopy based on optically transparent micro-ring ultrasonic detection.

PubMed

Dong, Biqin; Li, Hao; Zhang, Zhen; Zhang, Kevin; Chen, Siyu; Sun, Cheng; Zhang, Hao F

2015-01-01

Photoacoustic microscopy (PAM) is an attractive imaging tool complementary to established optical microscopic modalities by providing additional molecular specificities through imaging optical absorption contrast. While the development of optical resolution photoacoustic microscopy (ORPAM) offers high lateral resolution, the acoustically-determined axial resolution is limited due to the constraint in ultrasonic detection bandwidth. ORPAM with isometric spatial resolution along both axial and lateral direction is yet to be developed. Although recently developed sophisticated optical illumination and reconstruction methods offer improved axial resolution in ORPAM, the image acquisition procedures are rather complicated, limiting their capabilities for high-speed imaging and being easily integrated with established optical microscopic modalities. Here we report an isometric ORPAM based on an optically transparent micro-ring resonator ultrasonic detector and a commercial inverted microscope platform. Owing to the superior spatial resolution and the ease of integrating our ORPAM with established microscopic modalities, single cell imaging with extrinsic fluorescence staining, intrinsic autofluorescence, and optical absorption can be achieved simultaneously. This technique holds promise to greatly improve the accessibility of PAM to the broader biomedical researchers.

OSMOSIS: a new joint laboratory between SOFRADIR and ONERA for the development of advanced DDCA with integrated optics

NASA Astrophysics Data System (ADS)

Druart, Guillaume; Matallah, Noura; Guerineau, Nicolas; Magli, Serge; Chambon, Mathieu; Jenouvrier, Pierre; Mallet, Eric; Reibel, Yann

2014-06-01

Today, both military and civilian applications require miniaturized optical systems in order to give an imagery function to vehicles with small payload capacity. After the development of megapixel focal plane arrays (FPA) with micro-sized pixels, this miniaturization will become feasible with the integration of optical functions in the detector area. In the field of cooled infrared imaging systems, the detector area is the Detector-Dewar-Cooler Assembly (DDCA). SOFRADIR and ONERA have launched a new research and innovation partnership, called OSMOSIS, to develop disruptive technologies for DDCA to improve the performance and compactness of optronic systems. With this collaboration, we will break down the technological barriers of DDCA, a sealed and cooled environment dedicated to the infrared detectors, to explore Dewar-level integration of optics. This technological breakthrough will bring more compact multipurpose thermal imaging products, as well as new thermal capabilities such as 3D imagery or multispectral imagery. Previous developments will be recalled (SOIE and FISBI cameras) and new developments will be presented. In particular, we will focus on a dual-band MWIR-LWIR camera and a multichannel camera.

Hot-Electron Gallium Nitride Two Dimensional Electron Gas Nano-bolometers For Advanced THz Spectroscopy

NASA Astrophysics Data System (ADS)

Ramaswamy, Rahul

Two-dimensional electron gas (2DEG) in semiconductor heterostructures was identified as a promising medium for hot-electron bolometers (HEB) in the early 90s. Up until now all research based on 2DEG HEBs is done using high mobility AlGaAs/GaAs heterostructures. These systems have demonstrated very good performance, but only in the sub terahertz (THz) range. However, above ˜0.5 THz the performance of AlGaAs/GaAs detectors drastically deteriorates. It is currently understood, that detectors fabricated from standard AlGaAs/GaAs heterostructures do not allow for reasonable coupling to THz radiation while maintaining high conversion efficiency. In this work we have developed 2DEG HEBs based on disordered Gallium Nitride (GaN) semiconductor, that operate at frequencies beyond 1THz at room temperature. We observe strong free carrier absorption at THz frequencies in our disordered 2DEG film due to Drude absorption. We show the design and fabrication procedures of novel micro-bolometers having ultra-low heat capacities. In this work the mechanism of 2DEG response to THz radiation is clearly identified as bolometric effect through our direct detection measurements. With optimal doping and detector geometry, impedances of 10--100 O have been achieved, which allow integration of these devices with standard THz antennas. We also demonstrate performance of the antennas used in this work in effectively coupling THz radiation to the micro-bolometers through polarization dependence and far field measurements. Finally heterodyne mixing due to hot electrons in the 2DEG micro-bolometer has been performed at sub terahertz frequencies and a mixing bandwidth greater than 3GHz has been achieved. This indicates that the characteristic cooling time in our detectors is fast, less than 50ps. Due to the ultra-low heat capacity; these detectors can be used in a heterodyne system with a quantum cascade laser (QCL) as a local oscillator (LO) which typically provides output powers in the micro watt range. Our studies suggest that such room temperature detectors from GaN semiconductor, with reasonable bandwidth, low LO power requirements and high sensitivity have numerous applications, ranging from precise identification of complex molecules, environmental monitoring of critical substances, remote detection of various pollutants in the atmosphere, and noninvasive medical imaging as well as a variety of applications for defense and homeland security.

Synchronous-digitization for Video Rate Polarization Modulated Beam Scanning Second Harmonic Generation Microscopy.

PubMed

Sullivan, Shane Z; DeWalt, Emma L; Schmitt, Paul D; Muir, Ryan M; Simpson, Garth J

2015-03-09

Fast beam-scanning non-linear optical microscopy, coupled with fast (8 MHz) polarization modulation and analytical modeling have enabled simultaneous nonlinear optical Stokes ellipsometry (NOSE) and linear Stokes ellipsometry imaging at video rate (15 Hz). NOSE enables recovery of the complex-valued Jones tensor that describes the polarization-dependent observables, in contrast to polarimetry, in which the polarization stated of the exciting beam is recorded. Each data acquisition consists of 30 images (10 for each detector, with three detectors operating in parallel), each of which corresponds to polarization-dependent results. Processing of this image set by linear fitting contracts down each set of 10 images to a set of 5 parameters for each detector in second harmonic generation (SHG) and three parameters for the transmittance of the fundamental laser beam. Using these parameters, it is possible to recover the Jones tensor elements of the sample at video rate. Video rate imaging is enabled by performing synchronous digitization (SD), in which a PCIe digital oscilloscope card is synchronized to the laser (the laser is the master clock.) Fast polarization modulation was achieved by modulating an electro-optic modulator synchronously with the laser and digitizer, with a simple sine-wave at 1/10th the period of the laser, producing a repeating pattern of 10 polarization states. This approach was validated using Z-cut quartz, and NOSE microscopy was performed for micro-crystals of naproxen.

Synchronous-digitization for video rate polarization modulated beam scanning second harmonic generation microscopy

NASA Astrophysics Data System (ADS)

Sullivan, Shane Z.; DeWalt, Emma L.; Schmitt, Paul D.; Muir, Ryan D.; Simpson, Garth J.

2015-03-01

Fast beam-scanning non-linear optical microscopy, coupled with fast (8 MHz) polarization modulation and analytical modeling have enabled simultaneous nonlinear optical Stokes ellipsometry (NOSE) and linear Stokes ellipsometry imaging at video rate (15 Hz). NOSE enables recovery of the complex-valued Jones tensor that describes the polarization-dependent observables, in contrast to polarimetry, in which the polarization stated of the exciting beam is recorded. Each data acquisition consists of 30 images (10 for each detector, with three detectors operating in parallel), each of which corresponds to polarization-dependent results. Processing of this image set by linear fitting contracts down each set of 10 images to a set of 5 parameters for each detector in second harmonic generation (SHG) and three parameters for the transmittance of the fundamental laser beam. Using these parameters, it is possible to recover the Jones tensor elements of the sample at video rate. Video rate imaging is enabled by performing synchronous digitization (SD), in which a PCIe digital oscilloscope card is synchronized to the laser (the laser is the master clock.) Fast polarization modulation was achieved by modulating an electro-optic modulator synchronously with the laser and digitizer, with a simple sine-wave at 1/10th the period of the laser, producing a repeating pattern of 10 polarization states. This approach was validated using Z-cut quartz, and NOSE microscopy was performed for micro-crystals of naproxen.

Image quality assessment of a pre-clinical flat-panel volumetric micro-CT scanner

NASA Astrophysics Data System (ADS)

Du, Louise Y.; Lee, Ting-Yim; Holdsworth, David W.

2006-03-01

Small animal imaging has recently become an area of increased interest because more human diseases can be modeled in transgenic and knockout rodents. Current micro-CT systems are capable of achieving spatial resolution on the order of 10 μm, giving highly detailed anatomical information. However, the speed of data acquisition of these systems is relatively slow, when compared with clinical CT systems. Dynamic CT perfusion imaging has proven to be a powerful tool clinically in detecting and diagnosing cancer, stroke, pulmonary and ischemic heart diseases. In order to perform this technique in mice and rats, quantitative CT images must be acquired at a rate of at least 1 Hz. Recently, a research pre-clinical CT scanner (eXplore Ultra, GE Healthcare) has been designed specifically for dynamic perfusion imaging in small animals. Using an amorphous silicon flat-panel detector and a clinical slip-ring gantry, this system is capable of acquiring volumetric image data at a rate of 1 Hz, with in-plane resolution of 150 μm, while covering the entire thoracic region of a mouse or whole organs of a rat. The purpose of this study was to evaluate the principal imaging performance of the micro-CT system, in terms of spatial resolution, image uniformity, linearity, dose and voxel noise for the feasibility of imaging mice and rats. Our investigations show that 3D images can be obtained with a limiting spatial resolution of 2.7 line pairs per mm and noise of 42 HU, using an acquisition interval of 8 seconds at an entrance dose of 6.4 cGy.

The Pandora multi-algorithm approach to automated pattern recognition of cosmic-ray muon and neutrino events in the MicroBooNE detector

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

Acciarri, R.; Adams, C.; An, R.

The development and operation of Liquid-Argon Time-Projection Chambers for neutrino physics has created a need for new approaches to pattern recognition in order to fully exploit the imaging capabilities offered by this technology. Whereas the human brain can excel at identifying features in the recorded events, it is a significant challenge to develop an automated, algorithmic solution. The Pandora Software Development Kit provides functionality to aid the design and implementation of pattern-recognition algorithms. It promotes the use of a multi-algorithm approach to pattern recognition, in which individual algorithms each address a specific task in a particular topology. Many tens ofmore » algorithms then carefully build up a picture of the event and, together, provide a robust automated pattern-recognition solution. This paper describes details of the chain of over one hundred Pandora algorithms and tools used to reconstruct cosmic-ray muon and neutrino events in the MicroBooNE detector. Metrics that assess the current pattern-recognition performance are presented for simulated MicroBooNE events, using a selection of final-state event topologies.« less

The Pandora multi-algorithm approach to automated pattern recognition of cosmic-ray muon and neutrino events in the MicroBooNE detector

DOE PAGES

Acciarri, R.; Adams, C.; An, R.; ...

2018-01-29

The development and operation of Liquid-Argon Time-Projection Chambers for neutrino physics has created a need for new approaches to pattern recognition in order to fully exploit the imaging capabilities offered by this technology. Whereas the human brain can excel at identifying features in the recorded events, it is a significant challenge to develop an automated, algorithmic solution. The Pandora Software Development Kit provides functionality to aid the design and implementation of pattern-recognition algorithms. It promotes the use of a multi-algorithm approach to pattern recognition, in which individual algorithms each address a specific task in a particular topology. Many tens ofmore » algorithms then carefully build up a picture of the event and, together, provide a robust automated pattern-recognition solution. This paper describes details of the chain of over one hundred Pandora algorithms and tools used to reconstruct cosmic-ray muon and neutrino events in the MicroBooNE detector. Metrics that assess the current pattern-recognition performance are presented for simulated MicroBooNE events, using a selection of final-state event topologies.« less

Microminiature rotary Stirling cryocooler for compact, lightweight, and low-power thermal imaging systems

NASA Astrophysics Data System (ADS)

Filis, Avishai; Bar Haim, Zvi; Pundak, Nachman; Broyde, Ramon

2009-05-01

Novel compact and low power consuming cooled infrared thermal imagers as used in gyro-stabilized payloads of miniature unmanned aerial vehicles, Thermal small arms sights and tactical night vision goggles often rely on integral rotary micro-miniature closed cycle Stirling cryogenic engines. Development of EPI Antimonides technology and optimization of MCT technology allowed decreasing in order of magnitudes the level of dark current in infrared detectors thus enabling an increase in the optimal focal plane temperature in excess of 95K while keeping the same radiometric performances as achieved at 77K using regular technologies. Maintaining focal plane temperature in the range of 95K to 110K instead of 77K improves the efficiency of Stirling thermodynamic cycle thus enlarging cooling power and enabling the development of a mini micro cooler similar to RICOR's K562S model which is three times smaller, lighter and more compact than a standard tactical cryocooler like RICOR's K508 model. This cooler also features a new type of ball bearings and internal components which were optimized to fit tight bulk constraints and maintain the required life span, while keeping a low level of vibration and noise signature. Further, the functions of management the brushless DC motor and temperature stabilization are delivered by the newly developed high performance sensorless digital controller. By reducing Dewar Detector thermal losses and increasing the focal plane temperature, longer life time operation is expected as was proved with RICOR's K508 model. Resulting from this development, the RICOR K562S model cryogenic engine consumes 1.2 - 3.0 WDC while operating in the closed loop mode and maintaining the typical focal plane arrays at 200-100K. This makes it compatible with very compact battery packages allowing further reduction of the overall thermal imager weight thus making it comparable with the compatible uncooled infrared thermal imager relying on a microbolometer detector in terms of power consumption and bulk.

Demonstration of iodine K-edge imaging by use of an energy-discrimination X-ray computed tomography system with a cadmium telluride detector.

PubMed

Abudurexiti, Abulajiang; Kameda, Masashi; Sato, Eiichi; Abderyim, Purkhet; Enomoto, Toshiyuki; Watanabe, Manabu; Hitomi, Keitaro; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Takahashi, Kiyomi; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2010-07-01

An energy-discrimination K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region by utilizing contrast media. The CT system has a cadmium telluride (CdTe) detector, and a projection curve is obtained by linear scanning with use of the CdTe detector in conjunction with an X-stage. An object is rotated by a rotation step angle with use of a turntable between the linear scans. Thus, CT is carried out by repetition of the linear scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced with use of charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. For performing energy discrimination, a low-dose-rate X-ray generator for photon counting was developed; the maximum tube voltage and the minimum tube current were 110 kV and 1.0 microA, respectively. In energy-discrimination CT, the tube voltage and the current were 60 kV and 20.0 microA, respectively, and the X-ray intensity was 0.735 microGy/s at 1.0 m from the source and with a tube voltage of 60 kV. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selection of photons with energies just beyond the iodine K-edge energy of 33.2 keV.

Recent micro-CT scanner developments at UGCT

NASA Astrophysics Data System (ADS)

Dierick, Manuel; Van Loo, Denis; Masschaele, Bert; Van den Bulcke, Jan; Van Acker, Joris; Cnudde, Veerle; Van Hoorebeke, Luc

2014-04-01

This paper describes two X-ray micro-CT scanners which were recently developed to extend the experimental possibilities of microtomography research at the Centre for X-ray Tomography (www.ugct.ugent.be) of the Ghent University (Belgium). The first scanner, called Nanowood, is a wide-range CT scanner with two X-ray sources (160 kVmax) and two detectors, resolving features down to 0.4 μm in small samples, but allowing samples up to 35 cm to be scanned. This is a sample size range of 3 orders of magnitude, making this scanner well suited for imaging multi-scale materials such as wood, stone, etc. Besides the traditional cone-beam acquisition, Nanowood supports helical acquisition, and it can generate images with significant phase-contrast contributions. The second scanner, known as the Environmental micro-CT scanner (EMCT), is a gantry based micro-CT scanner with variable magnification for scanning objects which are not easy to rotate in a standard micro-CT scanner, for example because they are physically connected to external experimental hardware such as sensor wiring, tubing or others. This scanner resolves 5 μm features, covers a field-of-view of about 12 cm wide with an 80 cm vertical travel range. Both scanners will be extensively described and characterized, and their potential will be demonstrated with some key application results.

Large Area and High Efficiency Photon Counting Imaging Detectors with High Time and Spatial Resolution for Night Time Sensing and Astronomy

NASA Astrophysics Data System (ADS)

Siegmund, O.; Vallerga, J.; Tremsin, A.; McPhate, J.; Frisch, H.; Elam, J.; Mane, A.; Wagner, R.; Varner, G.

2012-09-01

The development of large area photon counting, imaging, timing detectors with high performance has significance for applications in astronomy (such as our sensor on the SAAO SALT 10m telescope), night time remote reconnaissance, airborne/space situational awareness, and high-speed adaptive optics. Sealed tube configurations for optical/IR sensing also have applications in detection of Cherenkov light (RICH), biological single-molecule fluorescence lifetime imaging microscopy and neutron imaging applications. In open faced configurations these devices are important for UV and particle detection in space astrophysics, mass spectroscopy and many time-of flight applications. Currently available devices are limited to sizes of about 5 cm and use either conventional microchannel plates, or dynode multipliers for amplification, coupled coarse pad array readouts. Extension of these schemes to devices as large as 20 cm with high spatial resolution presents significant problems and potentially considerable cost. A collaboration (Large Area Picosecond Photon Detector) of the U. Chicago, Argonne National Laboratory, U.C. Berkeley, U. Hawaii and a number of other institutions has developed novel technologies to realize 20 cm format detectors in open face or sealed tube configurations. One critical component of this development is novel microchannel plates employing borosilicate micro-capillary arrays. The microchannel plates are based on a novel concept where the substrate is constructed from a borosilicate micro-capillary array that is made to function as a microchannel plate by deposition of resistive and secondary emissive layers using atomic layer deposition. The process is relatively inexpensive compared with conventional microchannel plates and allows very large microchannel plates to be produced with pore sizes as small as 10 microns. These provide many performance characteristics typical of conventional microchannel plates, but have been made in sizes up to 20 cm, have low intrinsic background (<0.1 events/sq-cm/sec) and high stability with no observed gain degradation behavior over at least 5 Coul/sq-cm of charge extraction. Initial tests in a 20 cm detector with a cross strip electronic readout have achieved 4k x 4k pixel imaging with single photon sub-ns timing and MHz event rates. In concert with this effort we have made stable, uniform 20 cm bialkali photocathodes with >20% quantum efficiency on borosilicate windows compatible with a large sealed tube device. Other related efforts have also produced small sealed tubes with 30% quantum efficiency GaAs sealed tubes with high resolution imaging and timing that are immediately applicable to current applications, and opaque GaN UV photocathodes directly deposited onto these novel microchannel plates. We will discuss the details and implications of these novel microchannel plates with respect to the realization of novel detectors up to 20 cm format with reasonable cost and performance, robust construction, high flexibility of format and readout, reduction of fabrication effort, dramatically increased lifetime and stability, and their potential applications.

Third-generation imaging sensor system concepts

NASA Astrophysics Data System (ADS)

Reago, Donald A.; Horn, Stuart B.; Campbell, James, Jr.; Vollmerhausen, Richard H.

1999-07-01

Second generation forward looking infrared sensors, based on either parallel scanning, long wave (8 - 12 um) time delay and integration HgCdTe detectors or mid wave (3 - 5 um), medium format staring (640 X 480 pixels) InSb detectors, are being fielded. The science and technology community is now turning its attention toward the definition of a future third generation of FLIR sensors, based on emerging research and development efforts. Modeled third generation sensor performance demonstrates a significant improvement in performance over second generation, resulting in enhanced lethality and survivability on the future battlefield. In this paper we present the current thinking on what third generation sensors systems will be and the resulting requirements for third generation focal plane array detectors. Three classes of sensors have been identified. The high performance sensor will contain a megapixel or larger array with at least two colors. Higher operating temperatures will also be the goal here so that power and weight can be reduced. A high performance uncooled sensor is also envisioned that will perform somewhere between first and second generation cooled detectors, but at significantly lower cost, weight, and power. The final third generation sensor is a very low cost micro sensor. This sensor can open up a whole new IR market because of its small size, weight, and cost. Future unattended throwaway sensors, micro UAVs, and helmet mounted IR cameras will be the result of this new class.

Neutron Imaging Developments at LANSCE

NASA Astrophysics Data System (ADS)

Nelson, Ron; Hunter, James; Schirato, Richard; Vogel, Sven; Swift, Alicia; Ickes, Tim; Ward, Bill; Losko, Adrian; Tremsin, Anton

2015-10-01

Neutron imaging is complementary to x-ray imaging because of its sensitivity to light elements and greater penetration of high-Z materials. Energy-resolved neutron imaging can provide contrast enhancements for elements and isotopes due to the variations with energy in scattering cross sections due to nuclear resonances. These cross section differences exist due to compound nuclear resonances that are characteristic of each element and isotope, as well as broader resonances at higher energies. In addition, multi-probe imaging, such as combined photon and neutron imaging, is a powerful tool for discerning properties and features in materials that cannot be observed with a single probe. Recently, we have demonstrated neutron imaging, both radiography and computed tomography, using the moderated (Lujan Center) and high-energy (WNR facility) neutron sources at LANSCE. Flat panel x-ray detectors with suitable scintillator-converter screens provide good sensitivity for both low and high neutron energies. Micro-Channel-Plate detectors and iCCD scintillator camera systems that provide the fast time gating needed for energy-resolved imaging have been demonstrated as well. Examples of recent work will be shown including fluid flow in plants and imaging through dense thick objects. This work is funded by the US Department of Energy, National Nuclear Security Administration, and performed by Los Alamos National Security LLC under Contract DE-AC52-06NA25396.

Histogram-driven cupping correction (HDCC) in CT

NASA Astrophysics Data System (ADS)

Kyriakou, Y.; Meyer, M.; Lapp, R.; Kalender, W. A.

2010-04-01

Typical cupping correction methods are pre-processing methods which require either pre-calibration measurements or simulations of standard objects to approximate and correct for beam hardening and scatter. Some of them require the knowledge of spectra, detector characteristics, etc. The aim of this work was to develop a practical histogram-driven cupping correction (HDCC) method to post-process the reconstructed images. We use a polynomial representation of the raw-data generated by forward projection of the reconstructed images; forward and backprojection are performed on graphics processing units (GPU). The coefficients of the polynomial are optimized using a simplex minimization of the joint entropy of the CT image and its gradient. The algorithm was evaluated using simulations and measurements of homogeneous and inhomogeneous phantoms. For the measurements a C-arm flat-detector CT (FD-CT) system with a 30×40 cm2 detector, a kilovoltage on board imager (radiation therapy simulator) and a micro-CT system were used. The algorithm reduced cupping artifacts both in simulations and measurements using a fourth-order polynomial and was in good agreement to the reference. The minimization algorithm required less than 70 iterations to adjust the coefficients only performing a linear combination of basis images, thus executing without time consuming operations. HDCC reduced cupping artifacts without the necessity of pre-calibration or other scan information enabling a retrospective improvement of CT image homogeneity. However, the method can work with other cupping correction algorithms or in a calibration manner, as well.

Chinese Manned Space Utility Project

NASA Astrophysics Data System (ADS)

Gu, Y.

Since 1992 China has been carrying out a conspicuous manned space mission A utility project has been defined and created during the same period The Utility Project of the Chinese Manned Space Mission involves wide science areas such as earth observation life science micro-gravity fluid physics and material science astronomy space environment etc In the earth observation area it is focused on the changes of global environments and relevant exploration technologies A Middle Revolution Image Spectrometer and a Multi-model Micro-wave Remote Sensor have been developed The detectors for cirrostratus distribution solar constant earth emission budget earth-atmosphere ultra-violet spectrum and flux have been manufactured and tested All of above equipment was engaged in orbital experiments on-board the Shenzhou series spacecrafts Space life science biotechnologies and micro-gravity science were much concerned with the project A series of experiments has been made both in ground laboratories and spacecraft capsules The environmental effect in different biological bodies in space protein crystallization electrical cell-fusion animal cells cultural research on separation by using free-low electrophoresis a liquid drop Marangoni migration experiment under micro-gravity as well as a set of crystal growth and metal processing was successfully operated in space The Gamma-ray burst and high-energy emission from solar flares have been explored A set of particle detectors and a mass spectrometer measured

Micro-XRF for In Situ Geological Exploration of Other Planets

NASA Technical Reports Server (NTRS)

Wade, Lawrence A.; Hodyss, Robert P.; Allwood, Abigail C.; Gao, Ning; Kozaczek, Kris

2013-01-01

In situ analysis of rock chemistry is a fundamental tool for exploration of planets. To meet this need, a high-spatial-resolution micro x-ray fluorescence (Micro-XRF) instrument was developed that is capable of determining the elemental composition of rocks (elements Na U) with 100 microns spatial resolution, thus providing insight to the composition of features as small as sand grains and individual laminae. The resulting excitation beam is of sufficient intensity that high signal-to-noise punctual spectra are acquired in seconds to a few minutes using an Amptek Silicon Drift Detector (SDD). The instrument features a tightly focused x-ray tube and HVPS developed by Moxtek that provides up to 200 micro-A at 10 to 50 keV, with a custom polycapillary optic developed by XOS Inc. and integrated into a breadboard Micro-XRF (see figure). The total mass of the complete breadboard instrument is 2.76 kg, including mounting hardware, mounting plate, camera, laser, etc. A flight version of this instrument would require less than 5W nominal power and 1.5 kg mass. The instrument includes an Amptek SDD that draws 2.5 W and has a resolution of 135 to 155 eV FWHM at 5.9 keV. It weighs 180 g, including the preamplifier, digital pulse processor, multichannel analyzer, detector and preamp power supplies, and packaging. Rock samples are positioned relative to the instrument by a three-axis arm whose position is controlled by closed-loop translators (mimicking the robotic arm of a rover). The distance from the source to the detector is calculated from the position of a focused laser beam on the sample as imaged by the camera. The instrument enables quick scans of major elements in only 1 second, and rapid acquisition (30 s) of data with excellent signal-to-noise and energy resolution for trace element analysis

Lensfree microscopy on a cellphone

PubMed Central

Tseng, Derek; Mudanyali, Onur; Oztoprak, Cetin; Isikman, Serhan O.; Sencan, Ikbal; Yaglidere, Oguzhan; Ozcan, Aydogan

2010-01-01

We demonstrate lensfree digital microscopy on a cellphone. This compact and light-weight holographic microscope installed on a cellphone does not utilize any lenses, lasers or other bulky optical components and it may offer a cost-effective tool for telemedicine applications to address various global health challenges. Weighing ~38 grams (<1.4 ounces), this lensfree imaging platform can be mechanically attached to the camera unit of a cellphone where the samples are loaded from the side, and are vertically illuminated by a simple light-emitting diode (LED). This incoherent LED light is then scattered from each micro-object to coherently interfere with the background light, creating the lensfree hologram of each object on the detector array of the cellphone. These holographic signatures captured by the cellphone permit reconstruction of microscopic images of the objects through rapid digital processing. We report the performance of this lensfree cellphone microscope by imaging various sized micro-particles, as well as red blood cells, white blood cells, platelets and a waterborne parasite (Giardia lamblia). PMID:20445943

Thermal and hydrodynamic studies for micro-channel cooling for large area silicon sensors in high energy physics experiments

NASA Astrophysics Data System (ADS)

Flaschel, Nils; Ariza, Dario; Díez, Sergio; Gerboles, Marta; Gregor, Ingrid-Maria; Jorda, Xavier; Mas, Roser; Quirion, David; Tackmann, Kerstin; Ullan, Miguel

2017-08-01

Micro-channel cooling initially aiming at small-sized high-power integrated circuits is being transferred to the field of high energy physics. Today's prospects of micro-fabricating silicon opens a door to a more direct cooling of detector modules. The challenge in high energy physics is to save material in the detector construction and to cool large areas. In this paper, we are investigating micro-channel cooling as a candidate for a future cooling system for silicon detectors in a generic research and development approach. The work presented in this paper includes the production and the hydrodynamic and thermal testing of a micro-channel equipped prototype optimized to achieve a homogeneous flow distribution. Furthermore, the device was simulated using finite element methods.

3D sensors and micro-fabricated detector systems

NASA Astrophysics Data System (ADS)

Da Vià, Cinzia

2014-11-01

Micro-systems based on the Micro Electro Mechanical Systems (MEMS) technology have been used in miniaturized low power and low mass smart structures in medicine, biology and space applications. Recently similar features found their way inside high energy physics with applications in vertex detectors for high-luminosity LHC Upgrades, with 3D sensors, 3D integration and efficient power management using silicon micro-channel cooling. This paper reports on the state of this development.

A highly accurate wireless digital sun sensor based on profile detecting and detector multiplexing technologies

NASA Astrophysics Data System (ADS)

Wei, Minsong; Xing, Fei; You, Zheng

2017-01-01

The advancing growth of micro- and nano-satellites requires miniaturized sun sensors which could be conveniently applied in the attitude determination subsystem. In this work, a profile detecting technology based high accurate wireless digital sun sensor was proposed, which could transform a two-dimensional image into two-linear profile output so that it can realize a high update rate under a very low power consumption. A multiple spots recovery approach with an asymmetric mask pattern design principle was introduced to fit the multiplexing image detector method for accuracy improvement of the sun sensor within a large Field of View (FOV). A FOV determination principle based on the concept of FOV region was also proposed to facilitate both sub-FOV analysis and the whole FOV determination. A RF MCU, together with solar cells, was utilized to achieve the wireless and self-powered functionality. The prototype of the sun sensor is approximately 10 times lower in size and weight compared with the conventional digital sun sensor (DSS). Test results indicated that the accuracy of the prototype was 0.01° within a cone FOV of 100°. Such an autonomous DSS could be equipped flexibly on a micro- or nano-satellite, especially for highly accurate remote sensing applications.

Fabrication and Testing of a Modular Micro-Pocket Fission Detector Instrumentation System for Test Nuclear Reactors

NASA Astrophysics Data System (ADS)

Reichenberger, Michael A.; Nichols, Daniel M.; Stevenson, Sarah R.; Swope, Tanner M.; Hilger, Caden W.; Roberts, Jeremy A.; Unruh, Troy C.; McGregor, Douglas S.

2018-01-01

Advancements in nuclear reactor core modeling and computational capability have encouraged further development of in-core neutron sensors. Measurement of the neutron-flux distribution within the reactor core provides a more complete understanding of the operating conditions in the reactor than typical ex-core sensors. Micro-Pocket Fission Detectors have been developed and tested previously but have been limited to single-node operation and have utilized highly specialized designs. The development of a widely deployable, multi-node Micro-Pocket Fission Detector assembly will enhance nuclear research capabilities. A modular, four-node Micro-Pocket Fission Detector array was designed, fabricated, and tested at Kansas State University. The array was constructed from materials that do not significantly perturb the neutron flux in the reactor core. All four sensor nodes were equally spaced axially in the array to span the fuel-region of the reactor core. The array was filled with neon gas, serving as an ionization medium in the small cavities of the Micro-Pocket Fission Detectors. The modular design of the instrument facilitates the testing and deployment of numerous sensor arrays. The unified design drastically improved device ruggedness and simplified construction from previous designs. Five 8-mm penetrations in the upper grid plate of the Kansas State University TRIGA Mk. II research nuclear reactor were utilized to deploy the array between fuel elements in the core. The Micro-Pocket Fission Detector array was coupled to an electronic support system which has been specially developed to support pulse-mode operation. The Micro-Pocket Fission Detector array composed of four sensors was used to monitor local neutron flux at a constant reactor power of 100 kWth at different axial locations simultaneously. The array was positioned at five different radial locations within the core to emulate the deployment of multiple arrays and develop a 2-dimensional measurement of neutron flux in the reactor core.

Depth-of-interaction estimates in pixelated scintillator sensors using Monte Carlo techniques

NASA Astrophysics Data System (ADS)

Sharma, Diksha; Sze, Christina; Bhandari, Harish; Nagarkar, Vivek; Badano, Aldo

2017-01-01

Image quality in thick scintillator detectors can be improved by minimizing parallax errors through depth-of-interaction (DOI) estimation. A novel sensor for low-energy single photon imaging having a thick, transparent, crystalline pixelated micro-columnar CsI:Tl scintillator structure has been described, with possible future application in small-animal single photon emission computed tomography (SPECT) imaging when using thicker structures under development. In order to understand the fundamental limits of this new structure, we introduce cartesianDETECT2, an open-source optical transport package that uses Monte Carlo methods to obtain estimates of DOI for improving spatial resolution of nuclear imaging applications. Optical photon paths are calculated as a function of varying simulation parameters such as columnar surface roughness, bulk, and top-surface absorption. We use scanning electron microscope images to estimate appropriate surface roughness coefficients. Simulation results are analyzed to model and establish patterns between DOI and photon scattering. The effect of varying starting locations of optical photons on the spatial response is studied. Bulk and top-surface absorption fractions were varied to investigate their effect on spatial response as a function of DOI. We investigated the accuracy of our DOI estimation model for a particular screen with various training and testing sets, and for all cases the percent error between the estimated and actual DOI over the majority of the detector thickness was ±5% with a maximum error of up to ±10% at deeper DOIs. In addition, we found that cartesianDETECT2 is computationally five times more efficient than MANTIS. Findings indicate that DOI estimates can be extracted from a double-Gaussian model of the detector response. We observed that our model predicts DOI in pixelated scintillator detectors reasonably well.

Micro-Hall devices for magnetic, electric and photo-detection

NASA Astrophysics Data System (ADS)

Gilbertson, A.; Sadeghi, H.; Panchal, V.; Kazakova, O.; Lambert, C. J.; Solin, S. A.; Cohen, L. F.

Multifunctional mesoscopic sensors capable of detecting local magnetic (B) , electric (E) , and optical fields can greatly facilitate image capture in nano-arrays that address a multitude of disciplines. The use of micro-Hall devices as B-field sensors and, more recently as E-field sensors is well established. Here we report the real-space voltage response of InSb/AlInSb micro-Hall devices to not only local E-, and B-fields but also to photo-excitation using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local E-fields. Our experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. At room temperature, samples exhibit a magnetic sensitivity of >500 nT/ √Hz, an optical noise equivalent power of >20 pW/ √Hz (λ = 635 nm) comparable to commercial photoconductive detectors, and charge sensitivity of >0.04 e/ √Hz comparable to that of single electron transistors. Work done while on sabbatical from Washington University. Co-founder of PixelEXX, a start-up whose focus is imaging nano-arrays.

Energy-Discriminative Performance of a Spectral Micro-CT System

PubMed Central

He, Peng; Yu, Hengyong; Bennett, James; Ronaldson, Paul; Zainon, Rafidah; Butler, Anthony; Butler, Phil; Wei, Biao; Wang, Ge

2013-01-01

Experiments were performed to evaluate the energy-discriminative performance of a spectral (multi-energy) micro-CT system. The system, designed by MARS (Medipix All Resolution System) Bio-Imaging Ltd. (Christchurch, New Zealand), employs a photon-counting energy-discriminative detector technology developed by CERN (European Organization for Nuclear Research). We used the K-edge attenuation characteristic of some known materials to calibrate the detector’s photon energy discrimination. For tomographic analysis, we used the compressed sensing (CS) based ordered-subset simultaneous algebraic reconstruction techniques (OS-SART) to reconstruct sample images, which is effective to reduce noise and suppress artifacts. Unlike conventional CT, the principal component analysis (PCA) method can be applied to extract and quantify additional attenuation information from a spectral CT dataset. Our results show that the spectral CT has a good energy-discriminative performance and provides more attenuation information than the conventional CT. PMID:24004864

Maia Mapper: high definition XRF imaging in the lab

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

Ryan, Chris G.; Kirkham, R.; Moorhead, G. F.

Here, Maia Mapper is a laboratory μXRF mapping system for efficient elemental imaging of drill core sections serving minerals research and industrial applications. It targets intermediate spatial scales, with imaging of up to ~80 M pixels over a 500×150 mm 2 sample area. It brings together (i) the Maia detector and imaging system, with its large solid-angle, event-mode operation, millisecond pixel transit times in fly-scan mode and real-time spectral deconvolution and imaging, (ii) the high brightness MetalJet D2 liquid metal micro-focus X-ray source from Excillum, and (iii) an efficient XOS polycapillary lens with a flux gain ~15,900 at 21 keVmore » into a ~32 μm focus, and (iv) a sample scanning stage engineered for standard drill-core sections. Count-rates up to ~3 M/s are observed on drill core samples with low dead-time up to ~1.5%. Automated scans are executed in sequence with display of deconvoluted element component images accumulated in real-time in the Maia detector. Application images on drill core and polished rock slabs illustrate Maia Mapper capabilities as part of the analytical workflow of the Advanced Resource Characterisation Facility, which spans spatial dimensions from ore deposit to atomic scales.« less

Maia Mapper: high definition XRF imaging in the lab

DOE PAGES

Ryan, Chris G.; Kirkham, R.; Moorhead, G. F.; ...

2018-03-13

Here, Maia Mapper is a laboratory μXRF mapping system for efficient elemental imaging of drill core sections serving minerals research and industrial applications. It targets intermediate spatial scales, with imaging of up to ~80 M pixels over a 500×150 mm 2 sample area. It brings together (i) the Maia detector and imaging system, with its large solid-angle, event-mode operation, millisecond pixel transit times in fly-scan mode and real-time spectral deconvolution and imaging, (ii) the high brightness MetalJet D2 liquid metal micro-focus X-ray source from Excillum, and (iii) an efficient XOS polycapillary lens with a flux gain ~15,900 at 21 keVmore » into a ~32 μm focus, and (iv) a sample scanning stage engineered for standard drill-core sections. Count-rates up to ~3 M/s are observed on drill core samples with low dead-time up to ~1.5%. Automated scans are executed in sequence with display of deconvoluted element component images accumulated in real-time in the Maia detector. Application images on drill core and polished rock slabs illustrate Maia Mapper capabilities as part of the analytical workflow of the Advanced Resource Characterisation Facility, which spans spatial dimensions from ore deposit to atomic scales.« less

Maia Mapper: high definition XRF imaging in the lab

NASA Astrophysics Data System (ADS)

Ryan, C. G.; Kirkham, R.; Moorhead, G. F.; Parry, D.; Jensen, M.; Faulks, A.; Hogan, S.; Dunn, P. A.; Dodanwela, R.; Fisher, L. A.; Pearce, M.; Siddons, D. P.; Kuczewski, A.; Lundström, U.; Trolliet, A.; Gao, N.

2018-03-01

Maia Mapper is a laboratory μXRF mapping system for efficient elemental imaging of drill core sections serving minerals research and industrial applications. It targets intermediate spatial scales, with imaging of up to ~80 M pixels over a 500×150 mm2 sample area. It brings together (i) the Maia detector and imaging system, with its large solid-angle, event-mode operation, millisecond pixel transit times in fly-scan mode and real-time spectral deconvolution and imaging, (ii) the high brightness MetalJet D2 liquid metal micro-focus X-ray source from Excillum, and (iii) an efficient XOS polycapillary lens with a flux gain ~15,900 at 21 keV into a ~32 μm focus, and (iv) a sample scanning stage engineered for standard drill-core sections. Count-rates up to ~3 M/s are observed on drill core samples with low dead-time up to ~1.5%. Automated scans are executed in sequence with display of deconvoluted element component images accumulated in real-time in the Maia detector. Application images on drill core and polished rock slabs illustrate Maia Mapper capabilities as part of the analytical workflow of the Advanced Resource Characterisation Facility, which spans spatial dimensions from ore deposit to atomic scales.

The Fermilab Short-Baseline Program: MicroBooNE

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

Schukraft, Anne

2016-01-01

The MicroBooNE experiment is the first of three detectors of the Fermilab short-baseline neutrino program that started operation in the Booster Neutrino Beamline in October 2015 [1]. When completed, the three-detector lineup will explore short-baseline neutrino oscillations and will be sensitive to sterile neutrino scenarios. MicroBooNE in itself is now starting its own physics program, with the measurement of neutrino-argon cross sections in the ~1GeV range being one of its main physics goals. These proceedings describe the status of the detector, the start of operation, and the automated reconstruction of the first neutrino events observed with MicroBooNE. Prospects for upcomingmore » cross section measurements are also given.« less

A Wide Dynamic Range Tapped Linear Array Image Sensor

NASA Astrophysics Data System (ADS)

Washkurak, William D.; Chamberlain, Savvas G.; Prince, N. Daryl

1988-08-01

Detectors for acousto-optic signal processing applications require fast transient response as well as wide dynamic range. There are two major choices of detectors: conductive or integration mode. Conductive mode detectors have an initial transient period before they reach then' i equilibrium state. The duration of 1 his period is dependent on light level as well as detector capacitance. At low light levels a conductive mode detector is very slow; response time is typically on the order of milliseconds. Generally. to obtain fast transient response an integrating mode detector is preferred. With integrating mode detectors. the dynamic range is determined by the charge storage capability of the tran-sport shift registers and the noise level of the image sensor. The conventional net hod used to improve dynamic range is to increase the shift register charge storage capability. To achieve a dynamic range of fifty thousand assuming two hundred noise equivalent electrons, a charge storage capability of ten million electrons would be required. In order to accommodate this amount of charge. unrealistic shift registers widths would be required. Therefore, with an integrating mode detector it is difficult to achieve a dynamic range of over four orders of magnitude of input light intensity. Another alternative is to solve the problem at the photodetector aml not the shift, register. DALSA's wide dynamic range detector utilizes an optimized, ion implant doped, profiled MOSFET photodetector specifically designed for wide dynamic range. When this new detector operates at high speed and at low light levels the photons are collected and stored in an integrating fashion. However. at bright light levels where transient periods are short, the detector switches into a conductive mode. The light intensity is logarithmically compressed into small charge packets, easily carried by the CCD shift register. As a result of the logarithmic conversion, dynamic ranges of over six orders of magnitide are obtained. To achieve the short integration times necessary in acousto-optic applications. t he wide dynamic range detector has been implemented into a tapped array architecture with eight outputs and 256 photoelements. Operation of each 01)1,1)111 at 16 MHz yields detector integration times of 2 micro-seconds. Buried channel two phase CCD shift register technology is utilized to minimize image sensor noise improve video output rates and increase ease of operation.

Towards Quantum Experiments with Human Eyes as Detectors Based on Cloning via Stimulated Emission

NASA Astrophysics Data System (ADS)

Sekatski, Pavel; Brunner, Nicolas; Branciard, Cyril; Gisin, Nicolas; Simon, Christoph

2009-09-01

We show theoretically that a large Bell inequality violation can be obtained with human eyes as detectors, in a “micro-macro” experiment where one photon from an entangled pair is greatly amplified via stimulated emission. The violation is robust under photon loss. This leads to an apparent paradox, which we resolve by noting that the violation proves the existence of entanglement before the amplification. The same is true for the micro-macro experiments performed so far with conventional detectors. However, we also prove that there is genuine micro-macro entanglement even for high loss.

Experimental study of the rigidity and transparency to ionizing radiation of composite materials used in the enclosure under pressure of the Micromegas detector

NASA Astrophysics Data System (ADS)

Harbaoui, Imen; Besbes, Hatem; Chafra, Moez

Innovation in the field of nuclear imaging is necessarily followed by a radical change in the detection principle. The gas detector Micromegas (Mesh Micro Structure Gaseous) could be an interesting option, thanks to the stability and robustness of such a detector. Thus, it was necessary to study the implementation of the detector enclosure in composite materials. The focus of the present study was the robustness and gamma rays transparency of a set of composites. The studied composites were reinforced with vegetable fibers (alfa), and synthetic fibers. The mechanical properties of all composites specimen were evaluated by three-point bending test, whereas, gamma ray transparency was evaluated by the exposition of composites specimen to a mono-energetic gamma ray beam emitted by a Technetium 99-m source. Findings revealed that the biocomposite materials using alfa fiber and Polymethyl Methacrylate matrix are very promising as long as they present good robustness and high gamma ray transparency in diagnostic range.

Recent Developments in Transition-Edge Strip Detectors for Solar X-Rays

NASA Technical Reports Server (NTRS)

Rausch, Adam J.; Deiker, Steven W.; Hilton, Gene; Irwin, Kent D.; Martinez-Galarce, Dennis S.; Shing, Lawrence; Stern, Robert A.; Ullom, Joel N.; Vale, Leila R.

2008-01-01

LMSAL and NIST are developing position-sensitive x-ray strip detectors based on Transition Edge Sensor (TES) microcalorimeters optimized for solar physics. By combining high spectral (E/ delta E approximately equals 1600) and temporal (single photon delta t approximately equals 10 micro s) resolutions with imaging capabilities, these devices will be able to study high-temperature (>l0 MK) x-ray lines as never before. Diagnostics from these lines should provide significant new insight into the physics of both microflares and the early stages of flares. Previously, the large size of traditional TESs, along with the heat loads associated with wiring large arrays, presented obstacles to using these cryogenic detectors for solar missions. Implementing strip detector technology at small scales, however, addresses both issues: here, a line of substantially smaller effective pixels requires only two TESs, decreasing both the total array size and the wiring requirements for the same spatial resolution. Early results show energy resolutions of delta E(sub fwhm) approximately equals 30 eV and spatial resolutions of approximately 10-15 micron, suggesting the strip-detector concept is viable.

Improving Technology for Vascular Imaging

NASA Astrophysics Data System (ADS)

Rana, Raman

Neuro-endovascular image guided interventions (Neuro-EIGIs) is a minimally invasive procedure that require micro catheters and endovascular devices be inserted into the vasculature via an incision near the femoral artery and guided under low dose fluoroscopy to the vasculature of the head and neck. However, the endovascular devices used for the purpose are of very small size (stents are of the order of 50mum to 100mum) and the success of these EIGIs depends a lot on the accurate placement of these devices. In order to accurately place these devices inside the patient, the interventionalist should be able to see them clearly. Hence, high resolution capabilities are of immense importance in neuro-EIGIs. The high-resolution detectors, MAF-CCD and MAF-CMOS, at the Toshiba Stroke and Vascular Research Center at the University at Buffalo are capable of presenting improved images for better patient care. Focal spot of an x-ray tube plays an important role in performance of these high resolution detectors. The finite size of the focal spot results into the blurriness around the edges of the image of the object resulting in reduced spatial resolution. Hence, knowledge of accurate size of the focal spot of the x-ray tube is very essential for the evaluation of the total system performance. Importance of magnification and image detector blur deconvolution was demonstrated to carry out the more accurate measurement of x-ray focal spot using a pinhole camera. A 30 micron pinhole was used to obtain the focal spot images using flat panel detector (FPD) and different source to image distances (SIDs) were used to achieve different magnifications (3.16, 2.66 and 2.16). These focal spot images were deconvolved with a 2-D modulation transfer function (MTF), obtained using noise response (NR) method, to remove the detector blur present in the images. Using these corrected images, the accurate size of all the three focal spots were obtained and it was also established that effect of detector blur can be reduced significantly by using a higher magnification. As discussed earlier, interventionalist need higher resolution capabilities during EIGIs for more confident and successful treatment of the patient. An experimental MAF-CCD enabled with a Control, Acquisition, Processing, Image Display and Storage (CAPIDS) system was installed and aligned on a detector changer attached to the C-arm of a clinical angiographic unit. The CAPIDS system was developed and implemented using LabVIEW software and provides a user-friendly interface that enables control of several clinical radiographic imaging modes of the MAF including: fluoroscopy, roadmap, radiography, and digital-subtraction-angiography (DSA). Whenever the higher resolution is needed, the MAD-CCD detector can be moved in front of the FPD. A particular set of steps were needed to deploy the MAF in front of the FPD and to transfer the controls to CAPIDS from the Toshiba Systems. In order to minimize any possible negative impact of using two different detectors during a procedure, a well-designed workflow was developed that enables smooth deployment of the MAF at critical stages of clinical procedures. The images obtained using MAF-CCD detector demonstrated the advantages the high resolution imagers have over FPDs. Scatter is inevitable in x-ray imaging as it reduces the image quality. The benefit of removing the scatter is that it improves contrast and also increases the signal-to-Noise (SNR). There are various scatter reduction methods like air-gap techniques, collimation, moving anti-scatter grids, stationary anti-scatter grids. Stationary anti-scatter grids is a preferred choice in dynamic imaging because of its compact design and ease to use. However, when these anti-scatter grids are used with high resolution detector, there will be anti-scatter grid-line pattern present in the image, as structure noise. Because of presence of this anti-scatter grid artifact, the contrast-to-Noise (CNR) of the image decreases when grid is used with high resolution detector. In order to address this issue, grid-line artifact minimization method for high resolution detectors is developed. (Abstract shortened by ProQuest.).

Investigation of Very Fast Light Detectors: Silicon Photomultiplier and Micro PMT for a Cosmic Ray Array

NASA Astrophysics Data System (ADS)

Cervantes, Omar; Reyes, Liliana; Hooks, Tyler; Perez, Luis; Ritt, Stefan

2016-03-01

To construct a cosmic detector array using 4 scintillation detectors, we investigated 2 recent light sensor technologies from Hamamatsu, as possible readout detectors. First, we investigated several homemade versions of the multipixel photon counter (MPPC) light sensors. These detectors were either biased with internal or external high voltage power supplies. We made extensive measurements to confirm for the coincidence of the MPPC devices. Each sensor is coupled to a wavelength shifting fiber (WSF) that is embedded along a plastic scintillator sheet (30cmx60cmx1/4''). Using energetic cosmic rays, we evaluated several of these homemade detector modules placed above one another in a light proof enclosure. Next, we assembled 2 miniaturized micro photomultiplier (micro PMT), a device recently marketed by Hamamatsu. These sensors showed very fast response times. With 3 WSF embedded in scintillator sheets, we performed coincidence experiments. The detector waveforms were captured using the 5GS/sec domino ring sampler, the DRS4 and our workflow using the CERN PAW package and data analysis results would be presented. Title V Grant.

Graphics Processing Unit (GPU) implementation of image processing algorithms to improve system performance of the Control, Acquisition, Processing, and Image Display System (CAPIDS) of the Micro-Angiographic Fluoroscope (MAF).

PubMed

Vasan, S N Swetadri; Ionita, Ciprian N; Titus, A H; Cartwright, A N; Bednarek, D R; Rudin, S

2012-02-23

We present the image processing upgrades implemented on a Graphics Processing Unit (GPU) in the Control, Acquisition, Processing, and Image Display System (CAPIDS) for the custom Micro-Angiographic Fluoroscope (MAF) detector. Most of the image processing currently implemented in the CAPIDS system is pixel independent; that is, the operation on each pixel is the same and the operation on one does not depend upon the result from the operation on the other, allowing the entire image to be processed in parallel. GPU hardware was developed for this kind of massive parallel processing implementation. Thus for an algorithm which has a high amount of parallelism, a GPU implementation is much faster than a CPU implementation. The image processing algorithm upgrades implemented on the CAPIDS system include flat field correction, temporal filtering, image subtraction, roadmap mask generation and display window and leveling. A comparison between the previous and the upgraded version of CAPIDS has been presented, to demonstrate how the improvement is achieved. By performing the image processing on a GPU, significant improvements (with respect to timing or frame rate) have been achieved, including stable operation of the system at 30 fps during a fluoroscopy run, a DSA run, a roadmap procedure and automatic image windowing and leveling during each frame.

Performance of s-192 (hg,cd)te arrays.

PubMed

Aldrich, N C; Beck, J D

1972-10-01

Very high performance (Hg,Cd)Te photoconductive detectors have been fabricated for use on the S-192 experiment, which is a multispectral scanner being built by Honeywell for the NASA Manned Space Center's Skylab. The S-192 will scan the earth from Skylab and record data in twelve near ir spectral bands and one long wavelength band. The near ir bands range from 0.4 micro to 2.35 micro. At 87 K with a 90 degrees FOV, we have consistently produced arrays with specific detectivities at 2.35 micro close to or greater than 8 x 10(11) cm Hz((1/2))/W and with detective time constants less than 1 microsec. These detectors demonstrate good uniformity in performance across an array. State-of-the-art fabrication techniques have been used to make detectors with good definition that are 5-10 micro thick with 25-micro spacing between elements.

Performance Evaluation of the microPET®—FOCUS-F120

NASA Astrophysics Data System (ADS)

Laforest, Richard; Longford, Desmond; Siegel, Stefan; Newport, Danny F.; Yap, Jeffrey

2007-02-01

microPETreg-Focus-F120 is the latest model of dedicated small animal PET scanners from CTI-Concorde Microsystems LLC, (Knoxville, TN). This scanner, based on the geometry of the microPET-R4, takes advantage of several detector modifications to the coincidence processing electronics that improve the image resolution, sensitivity, and counting rate performance as compared to the predecessor models. This work evaluates the performance of the Focus-F120 system and shows its improvement over the earlier models. In particular, the spatial resolution is shown to improve from 2.32 to 1.69 mm at 5 mm radial distance and the peak absolute sensitivity increases from 4.1% to 7.1% compared to the microPET-R4. The counting rate capability, expressed in noise equivalent counting rate (NEC-1R), was shown to peak at over 800 kcps at 88 MBq for both systems using a mouse phantom. For this small phantom, the NECR counting rate is limited by the data transmission bandwidth between the scanner and the acquisition console. The rat-like phantom showed peak NEC-1R value at 300 kcps at 140 MBq. Evaluation of image quality and quantitation accuracy was also performed using specially designed phantoms and animal experiments

Design and construction of the MicroBooNE detector

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

Acciarri, R.; Adams, C.; An, R.

This paper describes the design and construction of the MicroBooNE liquid argon time projection chamber and associated systems. MicroBooNE is the first phase of the Short Baseline Neutrino program, located at Fermilab, and will utilize the capabilities of liquid argon detectors to examine a rich assortment of physics topics. In this document details of design specifications, assembly procedures, and acceptance tests are reported.

Design and construction of the MicroBooNE detector

DOE PAGES

Acciarri, R.; Adams, C.; An, R.; ...

2017-02-01

This paper describes the design and construction of the MicroBooNE liquid argon time projection chamber and associated systems. MicroBooNE is the first phase of the Short Baseline Neutrino program, located at Fermilab, and will utilize the capabilities of liquid argon detectors to examine a rich assortment of physics topics. In this document details of design specifications, assembly procedures, and acceptance tests are reported.

Study of Electromagnetic Interactions with the MicroBooNE Detector

NASA Astrophysics Data System (ADS)

Caratelli, David; MicroBooNE Collaboration

2017-01-01

MicroBooNE is an experiment which employs the Liquid Argon Time Projection Chamber (LArTPC) detector technology to study neutrinos produced with the Fermilab Booster Neutrino Beam. As for any accelerator-based detector interested in studying neutrino oscillations, it is essential to be able to identify and reconstruct the kinematic properties of electrons and photons produced in μν and νe interactions. We report current progress in reconstructing electron and photon electromagnetic (EM) showers using data from the MicroBooNE LArTPC. These studies cover EM showers in the tens to hundreds of MeV energy range; they lay the foundation for MicroBooNE's investigation of the excess of low-energy EM events reported by MiniBooNE, and are of interest to the wider LArTPC neutrino community.

TU-H-CAMPUS-TeP2-03: High Sensitivity and High Resolution Fiber Based Micro-Detector for Sub-Millimeter Preclinical Dosimetry

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

Izaguirre, E; Pokhrel, S; Knewtson, T

2016-06-15

Purpose: Current precision of small animal and cell micro-irradiators has continuously increased during the past years. Currently, preclinical irradiators can deliver sub-millimeter fields with micrometric precision but there are no water equivalent dosimeters to determine small field profiles and dose in the orthovoltage range of energies with micrometric resolution and precision. We have developed a fiber based micro-dosimeter with the resolution and dosimetric accuracy required for radiobiological research. Methods: We constructed two prototypes of micro-dosimeters based on different compositions of fiber scintillators to study the spatial resolution and dosimetric precision of small animal and cell micro-irradiators. The first has greenmore » output and the second has blue output. The blue output dosimeter has the highest sensitivity because it matches the spectral sensitivity of silicon photomultipliers. A blue detector with 500um cross section was built and tested respect to a CC01 ion chamber, film, and the 1500um green output detector. Orthovoltage fields from 1×1mm2 to 5×5mm2 were used for detector characteristics comparison. Results: The blue fiber dosimeter shows great agreement with films and matches dose measurements with the gold-standard ion chamber for 5×5mm2 fields. The detector has the appropriate sensitivity to measure fields from 1×1mm2 to larger sizes with a 1% dosimetric accuracy. The spatial resolution is in the sub-millimeter range and the spectral matching with the photomultiplier allows reducing the sensor cross section even further than the presented prototype. These results suggest that scintillating fibers combined with silicon photomultipliers is the appropriate technology to pursue micro-dosimetry for small animals and disperse cell samples. Conclusion: The constructed detectors establish a new landmark for the resolution and sensitivity of fiber based microdetectors. The validation of the detector in our small animal and cell irradiator shows that they are appropriate for preclinical and micro single cell irradiation quality assurance and dosimetry.« less

SYMPOSIUM ON MULTIMODALITY CARDIOVASCULAR MOLECULAR IMAGING IMAGING TECHNOLOGY - PART 2

PubMed Central

de Kemp, Robert A.; Epstein, Frederick H.; Catana, Ciprian; Tsui, Benjamin M.W.; Ritman, Erik L.

2013-01-01

Rationale The ability to trace or identify specific molecules within a specific anatomic location provides insight into metabolic pathways, tissue components and tracing of solute transport mechanisms. With the increasing use of small animals for research such imaging must have sufficiently high spatial resolution to allow anatomic localization as well as sufficient specificity and sensitivity to provide an accurate description of the molecular distribution and concentration. Methods Imaging methods based on electromagnetic radiation, such as PET, SPECT, MRI and CT, are increasingly applicable due to recent advances in novel scanner hardware, image reconstruction software and availability of novel molecules which have enhanced sensitivity in these methodologies. Results Micro-PET has been advanced by development of detector arrays that provide higher resolution and positron emitting elements that allow new molecular tracers to be labeled. Micro-MRI has been improved in terms of spatial resolution and sensitivity by increased magnet field strength and development of special purpose coils and associated scan protocols. Of particular interest is the associated ability to image local mechanical function and solute transport processes which can be directly related to the molecular information. This is further strengthened by the synergistic integration of the PET with MRI. Micro-SPECT has been improved by use of coded aperture imaging approaches as well as image reconstruction algorithms which can better deal with the photon limited scan data. The limited spatial resolution can be partially overcome by integrating the SPECT with CT. Micro-CT by itself provides exquisite spatial resolution of anatomy, but recent developments of high spatial resolution photon counting and spectrally-sensitive imaging arrays, combined with x-ray optical devices, have promise for actual molecular identification by virtue of the chemical bond lengths of molecules, especially of bio-polymers. Conclusion With the increasing use of small animals for evaluating new clinical imaging techniques as well as providing increased insights into patho-physiological phenomena, the availability of improved detection systems, scanning protocols and associated software, the repertoire of molecular imaging is greatly increased in sensitivity and specificity. PMID:20457793

Small field output factors evaluation with a microDiamond detector over 30 Italian centers.

PubMed

Russo, Serenella; Reggiori, Giacomo; Cagni, Elisabetta; Clemente, Stefania; Esposito, Marco; Falco, Maria Daniela; Fiandra, Christian; Giglioli, Francesca Romana; Marinelli, Marco; Marino, Carmelo; Masi, Laura; Pimpinella, Maria; Stasi, Michele; Strigari, Lidia; Talamonti, Cinzia; Villaggi, Elena; Mancosu, Pietro

2016-12-01

The aim of the study was a multicenter evaluation of MLC&jaws-defined small field output factors (OF) for different linear accelerator manufacturers and for different beam energies using the latest synthetic single crystal diamond detector commercially available. The feasibility of providing an experimental OF data set, useful for on-site measurements validation, was also evaluated. This work was performed in the framework of the Italian Association of Medical Physics (AIFM) SBRT working group. The project was subdivided in two phases: in the first phase each center measured OFs using their own routine detector for nominal field sizes ranging from 10×10cm 2 to 0.6×0.6cm 2 . In the second phase, the measurements were repeated in all centers using the PTW 60019 microDiamond detector. The project enrolled 30 Italian centers. Micro-ion chambers and silicon diodes were used for OF measurements in 24 and 6 centers respectively. Gafchromic films and TLDs were used for very small field OFs in 3 and 1 centers. Regarding the measurements performed with the user's detectors, OF standard deviations (SD) for field sizes down to 2×2cm 2 were in all cases <2.7%. In the second phase, a reduction of around 50% of the SD was obtained using the microDiamond detector. The measured values presented in this multicenter study provide a consistent dataset for OFs that could be a useful tool for improving dosimetric procedures in centers. The microDiamond data present a small variation among the centers confirming that this detector can contribute to improve overall accuracy in radiotherapy. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Classification of ring artifacts for their effective removal using type adaptive correction schemes.

PubMed

Anas, Emran Mohammad Abu; Lee, Soo Yeol; Hasan, Kamrul

2011-06-01

High resolution tomographic images acquired with a digital X-ray detector are often degraded by the so called ring artifacts. In this paper, a detail analysis including the classification, detection and correction of these ring artifacts is presented. At first, a novel idea for classifying rings into two categories, namely type I and type II rings, is proposed based on their statistical characteristics. The defective detector elements and the dusty scintillator screens result in type I ring and the mis-calibrated detector elements lead to type II ring. Unlike conventional approaches, we emphasize here on the separate detection and correction schemes for each type of rings for their effective removal. For the detection of type I ring, the histogram of the responses of the detector elements is used and a modified fast image inpainting algorithm is adopted to correct the responses of the defective pixels. On the other hand, to detect the type II ring, first a simple filtering scheme is presented based on the fast Fourier transform (FFT) to smooth the sum curve derived form the type I ring corrected projection data. The difference between the sum curve and its smoothed version is then used to detect their positions. Then, to remove the constant bias suffered by the responses of the mis-calibrated detector elements with view angle, an estimated dc shift is subtracted from them. The performance of the proposed algorithm is evaluated using real micro-CT images and is compared with three recently reported algorithms. Simulation results demonstrate superior performance of the proposed technique as compared to the techniques reported in the literature. Copyright © 2011 Elsevier Ltd. All rights reserved.

Performance analysis of a CsI-based flat panel detector in a cone beam variable resolution x-ray system

NASA Astrophysics Data System (ADS)

Dahi, Bahram; Keyes, Gary S.; Rendon, David A.; DiBianca, Frank A.

2007-03-01

A new Cone-Beam CT (CBCT) system is introduced that uses the concept of Variable Resolution X-ray (VRX) detection, which has previously been demonstrated to significantly increase spatial resolution for small objects. An amorphous silicon Flat Panel Detector (FPD) with a CsI scintillator (PaxScan 2020, Varian, Salt Lake City, UT) is coupled with a micro-focus x-ray tube (35 - 80 kVp, 10 - 250 μA) to form a CBCT. The FPD is installed on a rotating arm that can be adjusted to any angle θ, called the VRX angle, between 90° and 0° with respect to the x-ray direction. A VRX angle of 90° for the detector corresponds to a conventional CBCT whereas a VRX angle of 30° means that the detector is tilted 90° - 30° = 60° from its perpendicular position. Tilting the FPD in this manner reduces both the line-spread function width and the sampling distance by a factor of sin(θ), thereby increasing detector spatial resolution proportionately. An in-house phantom is used to measure the MTF of the reconstructed CT images using different VRX angles. An increase by a factor of 1.67 +/- 0.007 is observed in the MTF cutoff frequency at 30° compared to 90° in images acquired at 75 kVp. Expected theoretical value for this case is 2.0. The new Cone-Beam Variable Resolution X-ray (CB-VRX) CT system is expected to significantly improve the images acquired from small objects - such as small animals - while exploiting the opportunities offered by a conventional CBCT.

Integrated Micro-Chip Amino Acid Chirality Detector for MOD

NASA Technical Reports Server (NTRS)

Glavin, D. P.; Bada, J. L.; Botta, O.; Kminek, G.; Grunthaner, F.; Mathies, R.

2001-01-01

Integration of a micro-chip capillary electrophoresis analyzer with a sublimation-based extraction technique, as used in the Mars Organic Detector (MOD), for the in-situ detection of amino acids and their enantiomers on solar system bodies. Additional information is contained in the original extended abstract.

The MPGD-based photon detectors for the upgrade of COMPASS RICH-1

NASA Astrophysics Data System (ADS)

Alexeev, M.; Azevedo, C. D. R.; Birsa, R.; Bradamante, F.; Bressan, A.; Büchele, M.; Chiosso, M.; Ciliberti, P.; Dalla Torre, S.; Dasgupta, S.; Denisov, O.; Finger, M.; Finger, M.; Fischer, H.; Gobbo, B.; Gregori, M.; Hamar, G.; Herrmann, F.; Levorato, S.; Maggiora, A.; Makke, A.; Martin, A.; Menon, G.; Steiger, K.; Novy, J.; Panzieri, D.; Pereira, F. A. B.; Santos, C. A.; Sbrizzai, G.; Schopferer, S.; Slunecka, M.; Steiger, L.; Sulc, M.; Tessarotto, F.; Veloso, J. F. C. A.

2017-12-01

The RICH-1 Detector of the COMPASS experiment at CERN SPS has undergone an important upgrade for the 2016 physics run. Four new photon detectors, based on Micro Pattern Gaseous Detector technology and covering a total active area larger than 1.2 m2 have replaced the previously used MWPC-based photon detectors. The upgrade answers the challenging efficiency and stability quest for the new phase of the COMPASS spectrometer physics programme. The new detector architecture consists in a hybrid MPGD combination of two Thick Gas Electron Multipliers and a MicroMegas stage. Signals, extracted from the anode pad by capacitive coupling, are read-out by analog F-E based on the APV25 chip. The main aspects of the COMPASS RICH-1 photon detectors upgrade are presented focussing on detector design, engineering aspects, mass production, the quality assessment and assembly challenges of the MPGD components. The status of the detector commissioning is also presented.

Direct tests of micro channel plates as the active element of a new shower maximum detector

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

Ronzhin, A.; Los, S.; Ramberg, E.

2015-05-22

We continue the study of micro channel plates (MCP) as the active element of a shower maximum (SM) detector. We present below test beam results obtained with MCPs detecting directly secondary particles of an electromagnetic shower. The MCP efficiency to shower particles is close to 100%. Furthermore, the time resolution obtained for this new type of the SM detector is at the level of 40 ps.

Note: A timing micro-channel plate detector with backside fast preamplifier

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

Wang, Wei; University of Chinese Academy of Sciences, Beijing 100049; School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000

2014-03-15

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a {sup 241}Am α-source and a rise time of ∼2 ns with an output background noise of 4 mV{sub rms} was achieved.

Titanium bone implants with superimposed micro/nano-scale porosity and antibacterial capability

NASA Astrophysics Data System (ADS)

Necula, B. S.; Apachitei, I.; Fratila-Apachitei, L. E.; van Langelaan, E. J.; Duszczyk, J.

2013-05-01

This study aimed at producing a multifunctional layer with micro/nano-interconnected porosity and antibacterial capability on a rough macro-porous plasma sprayed titanium surface using the plasma electrolytic oxidation process. The layers were electrochemically formed in electrolytes based on calcium acetate and calcium glycerophosphate salts bearing dispersed Ag nanoparticles. They were characterized with respect to surface morphology and chemical composition using a scanning electron microscope equipped with the energy dispersive spectroscopy and back scattering detectors. Scanning electron microscopy images showed the formation of a micro/nano-scale porous layer, comprised of TiO2 bearing Ca and P species and Ag nanoparticles, following accurately the surface topography of the plasma sprayed titanium coating. The Ca/P atomic ratio was found to be close to that of bone apatite. Ag nanoparticles were incorporated on both on top and inside the porous structure of the TiO2 layer.

High throughput dual-wavelength temperature distribution imaging via compressive imaging

NASA Astrophysics Data System (ADS)

Yao, Xu-Ri; Lan, Ruo-Ming; Liu, Xue-Feng; Zhu, Ge; Zheng, Fu; Yu, Wen-Kai; Zhai, Guang-Jie

2018-03-01

Thermal imaging is an essential tool in a wide variety of research areas. In this work we demonstrate high-throughput double-wavelength temperature distribution imaging using a modified single-pixel camera without the requirement of a beam splitter (BS). A digital micro-mirror device (DMD) is utilized to display binary masks and split the incident radiation, which eliminates the necessity of a BS. Because the spatial resolution is dictated by the DMD, this thermal imaging system has the advantage of perfect spatial registration between the two images, which limits the need for the pixel registration and fine adjustments. Two bucket detectors, which measures the total light intensity reflected from the DMD, are employed in this system and yield an improvement in the detection efficiency of the narrow-band radiation. A compressive imaging algorithm is utilized to achieve under-sampling recovery. A proof-of-principle experiment was presented to demonstrate the feasibility of this structure.

WE-G-204-05: Relative Object Detectability Evaluation of a New High Resolution A-Se Direct Detection System Compared to Indirect Micro-Angiographic Fluoroscopic (MAF) Detectors

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

Russ, M; Nagesh, S Setlur; Ionita, C

2015-06-15

Purpose: To evaluate the task specific imaging performance of a new 25µm pixel pitch, 1000µm thick amorphous selenium direct detection system with CMOS readout for typical angiographic exposure parameters using the relative object detectability (ROD) metric. Methods: The ROD metric uses a simulated object function weighted at each spatial frequency by the detectors’ detective quantum efficiency (DQE), which is an intrinsic performance metric. For this study, the simulated objects were aluminum spheres of varying diameter (0.05–0.6mm). The weighted object function is then integrated over the full range of detectable frequencies inherent to each detector, and a ratio is taken ofmore » the resulting value for two detectors. The DQE for the 25µm detector was obtained from a simulation of a proposed a-Se detector using an exposure of 200µR for a 50keV x-ray beam. This a-Se detector was compared to two microangiographic fluoroscope (MAF) detectors [the MAF-CCD with pixel size of 35µm and Nyquist frequency of 14.2 cycles/mm and the MAF-CMOS with pixel size of 75µm and Nyquist frequency of 6.6 cycles/mm] and a standard flat-panel detector (FPD with pixel size of 194µm and Nyquist frequency of 2.5cycles/mm). Results: ROD calculations indicated vastly superior performance by the a-Se detector in imaging small aluminum spheres. For the 50µm diameter sphere, the ROD values for the a-Se detector compared to the MAF-CCD, the MAF-CMOS, and the FPD were 7.3, 9.3 and 58, respectively. Detector performance in the low frequency regime was dictated by each detector’s DQE(0) value. Conclusion: The a-Se with CMOS readout is unique and appears to have distinctive advantages of incomparable high resolution, low noise, no readout lag, and expandable design. The a-Se direct detection system will be a powerful imaging tool in angiography, with potential break-through applications in diagnosis and treatment of neuro-vascular disease. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.« less

Dosimetric characterization of a single crystal diamond detector in X-ray beams for preclinical research.

PubMed

Kampfer, Severin; Cho, Nathan; Combs, Stephanie E; Wilkens, Jan J

2018-05-29

The aim of this study was to investigate a single crystal diamond detector, the microDiamond detector from PTW (PTW-Freiburg, Freiburg, Germany), concerning the particular requirements in the set-up and energy range used in small animal radiotherapy (RT) research (around 220kV). We tested it to find out the minimal required pre-irradiation dose, the dose linearity, dose rate dependency and the angular response as well as usability in the small animal radiation research platform, SARRP (Xstrahl Ltd., Camberley, UK). For a stable signal in the range of energies used in the study, we found a required pre-irradiation dose of 10Gy. The dose linearity and dose rate dependence measurements showed a very good performance of the microDiamond detector. Regarding the effect of angular dependency, the variation of the response signal is less than 0.5% within the first 15° of the polar angle. In the azimuthal angle, however, there are differences in detector response up to 20%, depending on the range of energies used in the study. In addition, we compared the detector to a radiosensitive film for a profile measurement of a 5×5mm 2 irradiation field. Both methods showed a good accordance with the field size, however, the film has a steeper dose gradient in the penumbra region but also a higher noise than the microDiamond detector. We demonstrated that the microDiamond detector is a useful measurement tool for small animal RT research due to its small size. Nevertheless, it seems to be very important to verify the response of the detector in the given set-up and energy range. Copyright © 2018. Published by Elsevier GmbH.

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

Pal, Sambit Bikas; Haldar, Arijit; Roy, Basudev

A photonic force microscope comprises of an optically trapped micro-probe and a position detection system to track the motion of the probe. Signal collection for motion detection is often carried out using the backscattered light off the probe-however, this mode has problems of low S/N due to the small backscattering cross sections of the micro-probes typically used. The position sensors often used in these cases are quadrant photodetectors. To ensure maximum sensitivity of such detectors, it would help if the detector size matched with the detection beam radius after the condenser lens (which for backscattered detection would be the trappingmore » objective itself). To suit this condition, we have used a miniature displacement sensor whose dimensions makes it ideal to work with 1:1 images of micrometer-sized trapped probes in the backscattering detection mode. The detector is based on the quadrant photo-integrated chip in the optical pick-up head of a compact disc player. Using this detector, we measured absolute displacements of an optically trapped 1.1 {mu}m probe with a resolution of {approx}10 nm for a bandwidth of 10 Hz at 95% significance without any sample or laser stabilization. We characterized our optical trap for different sized probes by measuring the power spectrum for each probe to 1% accuracy, and found that for 1.1 {mu}m diameter probes, the noise in our position measurement matched the thermal resolution limit for averaging times up to 10 ms. We also achieved a linear response range of around 385 nm with cross talk between axes {approx_equal}4% for 1.1 {mu}m diameter probes. The detector has extremely high bandwidth (few MHz) and low optical power threshold-other factors that can lead to its widespread use in photonic force microscopy.« less

Integrated focal plane arrays for millimeter-wave astronomy

NASA Astrophysics Data System (ADS)

Bock, James J.; Goldin, Alexey; Hunt, Cynthia; Lange, Andrew E.; Leduc, Henry G.; Day, Peter K.; Vayonakis, Anastasios; Zmuidzinas, Jonas

2002-02-01

We are developing focal plane arrays of bolometric detectors for sub-millimeter and millimeter-wave astrophysics. We propose a flexible array architecture using arrays of slot antennae coupled via low-loss superconducting Nb transmission line to microstrip filters and antenna-coupled bolometers. By combining imaging and filtering functions with transmission line, we are able to realize unique structures such as a multi-band polarimeter and a planar, dispersive spectrometer. Micro-strip bolometers have significantly smaller active volume than standard detectors with extended absorbers, and can realize higher sensitivity and speed of response. The integrated array has natural immunity to stray radiation or spectral leaks, and minimizes the suspended mass operating at 0.1-0.3 K. We also discuss future space-borne spectroscopy and polarimetry applications. .

LPE grown LSO:Tb scintillator films for high-resolution X-ray imaging applications at synchrotron light sources

NASA Astrophysics Data System (ADS)

Cecilia, A.; Rack, A.; Douissard, P.-A.; Martin, T.; Dos Santos Rolo, T.; Vagovič, P.; Hamann, E.; van de Kamp, T.; Riedel, A.; Fiederle, M.; Baumbach, T.

2011-08-01

Within the project ScinTAX of the 6th framework program (FP6) of the European Commission (SCINTAX—STRP 033 427) we have developed a new thin single crystal scintillator for high-resolution X-ray imaging. The scintillator is based on a Tb-doped Lu2SiO5 (LSO) film epitaxially grown on an adapted substrate. The high density, effective atomic number and light yield of the scintillating LSO significantly improves the efficiency of the X-ray imaging detectors currently used in synchrotron micro-imaging applications. In this work we present the characterization of the scintillating LSO films in terms of their spatial resolution performance and we provide two examples of high spatial and high temporal resolution applications.

Mechanical studies towards a silicon micro-strip super module for the ATLAS inner detector upgrade at the high luminosity LHC

NASA Astrophysics Data System (ADS)

Barbier, G.; Cadoux, F.; Clark, A.; Endo, M.; Favre, Y.; Ferrere, D.; Gonzalez-Sevilla, S.; Hanagaki, K.; Hara, K.; Iacobucci, G.; Ikegami, Y.; Jinnouchi, O.; La Marra, D.; Nakamura, K.; Nishimura, R.; Perrin, E.; Seez, W.; Takubo, Y.; Takashima, R.; Terada, S.; Todome, K.; Unno, Y.; Weber, M.

2014-04-01

It is expected that after several years of data-taking, the Large Hadron Collider (LHC) physics programme will be extended to the so-called High-Luminosity LHC, where the instantaneous luminosity will be increased up to 5 × 1034 cm-2 s-1. For the general-purpose ATLAS experiment at the LHC, a complete replacement of its internal tracking detector will be necessary, as the existing detector will not provide the required performance due to the cumulated radiation damage and the increase in the detector occupancy. The baseline layout for the new ATLAS tracker is an all-silicon-based detector, with pixel sensors in the inner layers and silicon micro-strip detectors at intermediate and outer radii. The super-module (SM) is an integration concept proposed for the barrel strip region of the future ATLAS tracker, where double-sided stereo silicon micro-strip modules (DSM) are assembled into a low-mass local support (LS) structure. Mechanical aspects of the proposed LS structure are described.

Imaging and Rapid-Scanning Ion Mass Spectrometer (IRM) for the CASSIOPE e-POP Mission

NASA Astrophysics Data System (ADS)

Yau, Andrew W.; Howarth, Andrew; White, Andrew; Enno, Greg; Amerl, Peter

2015-06-01

The imaging and rapid-scanning ion mass spectrometer (IRM) is part of the Enhanced Polar Outflow Probe (e-POP) instrument suite on the Canadian CASSIOPE small satellite. Designed to measure the composition and detailed velocity distributions of ions in the ˜1-100 eV/q range on a non-spinning spacecraft, the IRM sensor consists of a planar entrance aperture, a pair of electrostatic deflectors, a time-of-flight (TOF) gate, a hemispherical electrostatic analyzer, and a micro-channel plate (MCP) detector. The TOF gate measures the transit time of each detected ion inside the sensor. The hemispherical analyzer disperses incident ions by their energy-per-charge and azimuth in the aperture plane onto the detector. The two electrostatic deflectors may be optionally programmed to step through a sequence of deflector voltages, to deflect ions of different incident elevation out of the aperture plane and energy-per-charge into the sensor aperture for sampling. The position and time of arrival of each detected ion at the detector are measured, to produce an image of 2-dimensional (2D), mass-resolved ion velocity distribution up to 100 times per second, or to construct a composite 3D velocity distribution by combining successive images in a deflector voltage sequence. The measured distributions are then used to investigate ion composition, density, drift velocity and temperature in polar ion outflows and related acceleration and transport processes in the topside ionosphere.

Cross delay line sensor characterization

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

Owens, Israel J; Remelius, Dennis K; Tiee, Joe J

There exists a wealth of information in the scientific literature on the physical properties and device characterization procedures for complementary metal oxide semiconductor (CMOS), charge coupled device (CCD) and avalanche photodiode (APD) format detectors. Numerous papers and books have also treated photocathode operation in the context of photomultiplier tube (PMT) operation for either non imaging applications or limited night vision capability. However, much less information has been reported in the literature about the characterization procedures and properties of photocathode detectors with novel cross delay line (XDL) anode structures. These allow one to detect single photons and create images by recordingmore » space and time coordinate (X, Y & T) information. In this paper, we report on the physical characteristics and performance of a cross delay line anode sensor with an enhanced near infrared wavelength response photocathode and high dynamic range micro channel plate (MCP) gain (> 10{sup 6}) multiplier stage. Measurement procedures and results including the device dark event rate (DER), pulse height distribution, quantum and electronic device efficiency (QE & DQE) and spatial resolution per effective pixel region in a 25 mm sensor array are presented. The overall knowledge and information obtained from XDL sensor characterization allow us to optimize device performance and assess capability. These device performance properties and capabilities make XDL detectors ideal for remote sensing field applications that require single photon detection, imaging, sub nano-second timing response, high spatial resolution (10's of microns) and large effective image format.« less

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

Cho, H; Ding, H; Molloi, S

Purpose: To investigate the feasibility of micro-calcification (μCa) detectability by using an energy-resolved photon-counting Si strip detector for spectral breast computed tomography (CT). Methods: A bench-top CT system was constructed using a tungsten anode x-ray source with a focal spot size of 0.8 mm and a single line 256-pixel Si strip photon counting detector with a pixel pitch of 100 μm. The slice thickness was 0.5 mm. Five different size groups of calcium carbonate grains, from 105 to 215 μm in diameter, were embedded in a cylindrical resin phantom with a diameter of 16 mm to simulate μCas. The phantomsmore » were imaged at 65 kVp with an Entrance Skin Air Kerma (ESAK) of 1.2, 3, 6, and 8 mGy. The images were reconstructed using a standard filtered back projection (FBP) with a ramp filter. A total of 200 μCa images (5 different sizes of μCas × 4 different doses × 10 images for each setting) were combined with another 200 control images without μCas, to ultimately form 400 images for the reader study. The images were displayed in random order to three blinded observers, who were asked to give a binary score on each image regarding the presence of μCas. The μCa detectability for each image was evaluated in terms of binary decision theory metrics. The sensitivity, specificity, and accuracy were calculated to study the size and dose-dependence for μCa detectability. Additionally, the influence of the partial volume effect on the μCa detectability was investigated by simulation. Results: For a μCa larger than 140 μm in diameter, detection accuracy of above 90 % was achieved with the investigated prototype spectral CT system at ESAK of 1.2 mGy. Conclusion: The proposed Si strip detector is expected to offer superior image quality with the capability to detect μCas for low dose breast imaging.« less

Large Area Flat Panel Imaging Detectors for Astronomy and Night Time Sensing

NASA Astrophysics Data System (ADS)

Siegmund, O.; McPhate, J.; Frisch, H.; Elam, J.; Mane, A.; Wagner, R.; Varner, G.

2013-09-01

Sealed tube photo-sensing detectors for optical/IR detection have applications in astronomy, nighttime remote reconnaissance, and airborne/space situational awareness. The potential development of large area photon counting, imaging, timing detectors has significance for these applications and a number of other areas (High energy particle detection (RICH), biological single-molecule fluorescence lifetime imaging microscopy, neutron imaging, time of flight mass spectroscopy, diffraction imaging). We will present details of progress towards the development of a 20 cm sealed tube optical detector with nanoengineered microchannel plates for photon counting, imaging and sub-ns event time stamping. In the operational scheme of the photodetector incoming light passes through an entrance window and interacts with a semitransparent photocathode on the inside of the window. The photoelectrons emitted are accelerated across a proximity gap and are detected by an MCP pair. The pair of novel borosilicate substrate MCPs are functionalized by atomic layer deposition (ALD), and amplify the signal and the resulting electron cloud is detected by a conductive strip line anode for determination of the event positions and the time of arrival. The physical package is ~ 25 x 25 cm but only 1.5 cm thick. Development of such a device in a square 20 cm format presents challenges: hermetic sealing to a large entrance window, a 20 cm semitransparent photocathode with good efficiency and uniformity, 20 cm MCPs with reasonable cost and performance, robust construction to preserve high vacuum and withstand an atmosphere pressure differential. We will discuss the schemes developed to address these issues and present the results for the first test devices. The novel microchannel plates employing borosilicate micro-capillary arrays provide many performance characteristics typical of conventional MCPs, but have been made in sizes up to 20 cm, have low intrinsic background (0.08 events cm2 s-1) and have very stable gain behavior over > 7 C cm2 of charge extracted. They are high temperature compatible and have minimal outgassing, which shortens and simplifies the sealed tube production process and should improve overall lifetimes. Bialkali (NaKSb) semitransparent photocathodes with > 20% quantum efficiency have also been made on 20 cm borosilicate windows compatible with the window seals for the large sealed tube device. The photocathodes have good response uniformity and have been stable for > 5 months in testing. Tests with a 20 cm detector with a cross delay line readout have achieved ~50µm FWHM imaging with single photon sub-ns timing and MHz event rates, and tests with a 10 x 10cm detector with cross strip readout has achieved ~20µm FWHM imaging with >4 MHz event rates with ~10% deadtime. We will discuss the details and implications of these novel detector implementations and their potential applications.

MicroCT imaging dose to mouse organs using a validated Monte Carlo model of the small animal radiation research platform (SARRP)

NASA Astrophysics Data System (ADS)

Johnstone, Christopher Daniel; Bazalova-Carter, Magdalena

2018-06-01

The goal of this work was to establish imaging dose to mouse organs with a validated Monte Carlo (MC) model of the image-guided Small Animal Radiation Research Platform (SARRP) and to investigate the effect of scatter from the internal walls on animal therapy dose determination. A MC model of the SARRP was built in the BEAMnrc code and validated with a series of homogeneous and heterogeneous phantom measurements. A segmented microCT scan of a mouse was used in DOSXYZnrc to determine mouse organ microCT imaging doses to 15–35 g mice for the SARRP pancake (mouse lying on couch) and standard (mouse standing on couch) imaging geometries for 40–80 kVp tube voltages. Imaging dose for off-center positioning shifts and maintaining image noise across tube voltages were also calculated. Half-value layer (HVL) measurements for the 220 kVp therapy beam in the presence of the SARRP shielding cabinet were modeled in BEAMnrc and compared to the 100 cm source-to-detector distance (SDD) in the scatter free, narrow-beam geometry recommended by the American Association of Physicists in Medicine Task Group 61 (AAPM TG-61). For a 60 kVp, 0.8 mA, and 60 s scan protocol, maximum mean organ imaging doses to boney and non-boney structures were 10.5 cGy and 3.5 cGy, respectively, for an average size 20 g mouse. Current-exposure combinations above 323, 203, 147, 116, and 95 mAs for 40–80 kVp tube voltages, respectively, will increase body doses above 10 cGy. MicroCT mean body dose was 18% lower in pancake compared to standard imaging geometry. An 11% difference in measured HVL at a 50 cm SDD was found compared to MC simulated HVL for the AAPM TG-61 recommended scatter free geometry at a 100 cm SDD. This change in HVL resulted in a 0.5% change in absorbed dose to water calculations for the treatment beam.

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

Gao, Lan; Hill, K. W.; Bitter, M.

Here, a high spatial resolution of a few μm is often required for probing small-scale high-energy-density plasmas using high resolution x-ray imaging spectroscopy. This resolution can be achieved by adjusting system magnification to overcome the inherent limitation of the detector pixel size. Laboratory experiments on investigating the relation between spatial resolution and system magnification for a spherical crystal spectrometer are presented. Tungsten Lβ 2 rays from a tungsten-target micro-focus x-ray tube were diffracted by a Ge 440 crystal, which was spherically bent to a radius of 223 mm, and imaged onto an x-ray CCD with 13-μm pixel size. The source-to-crystalmore » (p) and crystal-to-detector (q) distances were varied to produce spatial magnifications ( M = q/p) ranging from 2 to 10. The inferred instrumental spatial width reduces with increasing system magnification M. However, the experimental measurement at each M is larger than the theoretical value of pixel size divided by M. Future work will focus on investigating possible broadening mechanisms that limit the spatial resolution.« less

A study on the suitability of the PTW microDiamond detector for kilovoltage x-ray beam dosimetry.

PubMed

Damodar, Joshita; Odgers, David; Pope, Dane; Hill, Robin

2018-05-01

Kilovoltage x-ray beams are widely used in treating skin cancers and in biological irradiators. In this work, we have evaluated four dosimeters (ionization chambers and solid state detectors) in their suitability for relative dosimetry of kilovoltage x-ray beams in the energy range of 50 - 280kVp. The solid state detectors, which have not been investigated with low energy x-rays, were the PTW 60019 microDiamond synthetic diamond detector and the PTW 60012 diode. The two ionization chambers used were the PTW Advanced Markus parallel plate chamber and the PTW PinPoint small volume chamber. For each of the dosimeters, percentage depth doses were measured in water over the full range of x-ray beams and for field sizes ranging from 2cm diameter to 12 × 12cm. In addition, depth doses were measured for a narrow aperture (7mm diameter) using the PTW microDiamond detector. For comparison, the measured data was compared with Monte Carlo calculated doses using the EGSnrc Monte Carlo package. The depth dose results indicate that the Advanced Markus parallel plate and PinPoint ionization chambers were suitable for depth dose measurements in the beam quality range with an uncertainty of less than 3%, including in the regions closer to the surface of the water as compared with Monte Carlo depth dose data for all six energy beams. The response of the PTW Diode E detector was accurate to within 4% for all field sizes in the energy range of 50-125kVp but showed larger variations for higher energies of up to 12% with the 12 × 12cm field size. In comparison, the microDiamond detector had good agreement over all energies for both smaller and larger field sizes generally within 1% as compared to the Advanced Markus chamber field and Monte Carlo calculations. The only exceptions were in measuring the dose at the surface of the water phantom where larger differences were found. For the 7mm diameter field, the agreement between the microDiamond detector and Monte Carlo calculations was good being better than 1% except at the surface. Based on these results, the PTW microDiamond detector has shown to be a suitable detector for relative dosimetry of low energy x-ray beams over a wide range of x-ray beam energies. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Britton, C.L.; Jagadish, U.; Bryan, W.L.

An Integrated Circuit (IC) readout chip with four channels arranged so as to receive input charge from the corners of the chip was designed for use with 5- to 7-mm pixel detectors. This Application Specific IC (ASIC) can be used for cold neutron imaging, for study of structural order in materials using cold neutron scattering or for particle physics experiments. The ASIC is fabricated in a 0.5-{micro}m n-well AMI process. The design of the ASIC and the test measurements made is reported. Noise measurements are also reported.

A dedicated breast-PET/CT scanner: Evaluation of basic performance characteristics.

PubMed

Raylman, Raymond R; Van Kampen, Will; Stolin, Alexander V; Gong, Wenbo; Jaliparthi, Gangadhar; Martone, Peter F; Smith, Mark F; Sarment, David; Clinthorne, Neal H; Perna, Mark

2018-04-01

Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve detection of breast cancer. Unfortunately, both modalities have challenges in the detection of some lesions. The combination of the two techniques, however, could potentially lead to an overall improvement in diagnostic breast imaging. The purpose of this investigation is to test the basic performance of a new dedicated breast-PET/CT. The PET component consists of a rotating pair of detectors. Its performance was evaluated using the NEMA NU4-2008 protocols. The CT component utilizes a pulsed x ray source and flat panel detector mounted on the same gantry as the PET scanner. Its performance was assessed using specialized phantoms. The radiation dose to a breast during CT imaging was explored by the measurement of free-in-air kerma and air kerma measured at the center of a 16 cm-diameter PMMA cylinder. Finally, the combined capabilities of the system were demonstrated by imaging of a micro-hot-rod phantom. Overall, performance of the PET component is comparable to many pre-clinical and other dedicated breast-PET scanners. Its spatial resolution is 2.2 mm, 5 mm from the center of the scanner using images created with the single-sliced-filtered-backprojection algorithm. Peak NECR is 24.6 kcps; peak sensitivity is 1.36%; the scatter fraction is 27%. Spatial resolution of the CT scanner is 1.1 lp/mm at 10% MTF. The free-in-air kerma is 2.33 mGy, while the PMMA-air kerma is 1.24 mGy. Finally, combined imaging of a micro-hot-rod phantom illustrated the potential utility of the dual-modality images produced by the system. The basic performance characteristics of a new dedicated breast-PET/CT scanner are good, demonstrating that its performance is similar to current dedicated PET and CT scanners. The potential value of this system is the capability to produce combined duality-modality images that could improve detection of breast disease. The next stage in development of this system is testing with more advanced phantoms and human subjects. © 2018 American Association of Physicists in Medicine.

Cone-beam micro computed tomography dedicated to the breast.

PubMed

Sarno, Antonio; Mettivier, Giovanni; Di Lillo, Francesca; Cesarelli, Mario; Bifulco, Paolo; Russo, Paolo

2016-12-01

We developed a scanner for micro computed tomography dedicated to the breast (BµCT) with a high resolution flat-panel detector and a microfocus X-ray tube. We evaluated the system spatial resolution via the 3D modulation transfer function (MTF). In addition to conventional absorption-based X-ray imaging, such a prototype showed capabilities for propagation-based phase-contrast and related edge enhancement effects in 3D imaging. The system limiting spatial resolution is 6.2mm -1 (MTF at 10%) in the vertical direction and 3.8mm -1 in the radial direction, values which compare favorably with the spatial resolution reached by mini focus breast CT scanners of other groups. The BµCT scanner was able to detect both microcalcification clusters and masses in an anthropomorphic breast phantom at a dose comparable to that of two-view mammography. The use of a breast holder is proposed in order to have 1-2min long scan times without breast motion artifacts. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

The μ-RWELL: A compact, spark protected, single amplification-stage MPGD

NASA Astrophysics Data System (ADS)

Poli Lener, M.; Bencivenni, G.; de Olivera, R.; Felici, G.; Franchino, S.; Gatta, M.; Maggi, M.; Morello, G.; Sharma, A.

2016-07-01

In this work we present two innovative architectures of resistive MPGDs based on the WELL-amplification concept: - the micro-Resistive WELL (μ-RWELL) is a compact spark-protected single amplification-stage Micro-Pattern Gas Detector (MPGD). The amplification stage, realized with a structure very similar to a GEM foil (called WELL), is embedded through a resistive layer in the readout board. A cathode electrode, defining the gas conversion/drift gap, completes the detector mechanics. The new architecture, showing an excellent space resolution, 50 μm, is a very compact device, robust against discharges and exhibiting a large gain (>104), simple to construct and easy for engineering and then suitable for large area tracking devices as well as digital calorimeters. - the Fast Timing Micro-pattern (FTM): a new device with an architecture based on a stack of several coupled full-resistive layers where drift and multiplication stages (WELL type) alternate in the structure. The signals from each multiplication stage can be read out from any external readout boards through the capacitive couplings, providing a signal with a gain of 104-105. The main advantage of this new device is the improvement of the timing provided by the competition of the ionization processes in the different drift regions, which can be exploited for fast timing at the high luminosity accelerators (e.g. HL-LHC upgrade) as well as for applications like medical imaging.

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

NASA Astrophysics Data System (ADS)

Acciarri, R.; Adams, C.; An, R.; Anthony, J.; Asaadi, J.; Auger, M.; Bagby, L.; Balasubramanian, S.; Baller, B.; Barnes, C.; Barr, G.; Bass, M.; Bay, F.; Bishai, M.; Blake, A.; Bolton, T.; Camilleri, L.; Caratelli, D.; Carls, B.; Castillo Fernandez, R.; Cavanna, F.; Chen, H.; Church, E.; Cianci, D.; Cohen, E.; Collin, G. H.; Conrad, J. M.; Convery, M.; Crespo-Anadón, J. I.; Del Tutto, M.; Devitt, D.; Dytman, S.; Eberly, B.; Ereditato, A.; Escudero Sanchez, L.; Esquivel, J.; Fadeeva, A. A.; Fleming, B. T.; Foreman, W.; Furmanski, A. P.; Garcia-Gamez, D.; Garvey, G. T.; Genty, V.; Goeldi, D.; Gollapinni, S.; Graf, N.; Gramellini, E.; Greenlee, H.; Grosso, R.; Guenette, R.; Hackenburg, A.; Hamilton, P.; Hen, O.; Hewes, J.; Hill, C.; Ho, J.; Horton-Smith, G.; Hourlier, A.; Huang, E.-C.; James, C.; de Vries, J. Jan; Jen, C.-M.; Jiang, L.; Johnson, R. A.; Joshi, J.; Jostlein, H.; Kaleko, D.; Kalousis, L. N.; Karagiorgi, G.; Ketchum, W.; Kirby, B.; Kirby, M.; Kobilarcik, T.; Kreslo, I.; Lange, G.; Laube, A.; Li, Y.; Lister, A.; Littlejohn, B. R.; Lockwitz, S.; Lorca, D.; Louis, W. C.; Luethi, M.; Lundberg, B.; Luo, X.; Marchionni, A.; Mariani, C.; Marshall, J.; Martinez Caicedo, D. A.; Meddage, V.; Miceli, T.; Mills, G. B.; Moon, J.; Mooney, M.; Moore, C. D.; Mousseau, J.; Murrells, R.; Naples, D.; Nienaber, P.; Nowak, J.; Palamara, O.; Paolone, V.; Papavassiliou, V.; Pate, S. F.; Pavlovic, Z.; Pelkey, R.; Piasetzky, E.; Porzio, D.; Pulliam, G.; Qian, X.; Raaf, J. L.; Rafique, A.; Rochester, L.; von Rohr, C. Rudolf; Russell, B.; Schmitz, D. W.; Schukraft, A.; Seligman, W.; Shaevitz, M. H.; Sinclair, J.; Smith, A.; Snider, E. L.; Soderberg, M.; Söldner-Rembold, S.; Soleti, S. R.; Spentzouris, P.; Spitz, J.; John, J. St.; Strauss, T.; Szelc, A. M.; Tagg, N.; Terao, K.; Thomson, M.; Toups, M.; Tsai, Y.-T.; Tufanli, S.; Usher, T.; Van De Pontseele, W.; Van de Water, R. G.; Viren, B.; Weber, M.; Wickremasinghe, D. A.; Wolbers, S.; Wongjirad, T.; Woodruff, K.; Yang, T.; Yates, L.; Zeller, G. P.; Zennamo, J.; Zhang, C.

2017-12-01

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. We present a method of using an external 0.5 m (L) × 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersecting different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to be epsilondata=(97.1±0.1 (stat) ± 1.4 (sys))%, in good agreement with the Monte Carlo reconstruction efficiency epsilonMC = (97.4±0.1)%. This analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag ≈80% of the cosmic rays passing through the MicroBooNE detector.

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

DOE PAGES

Acciarri, R.; Adams, C.; An, R.; ...

2017-12-01

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. We present a method of using an external 0.5 m (L) x 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersecting different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to bemore » $$\\epsilon_{\\mathrm{data}}=(97.1\\pm0.1~(\\mathrm{stat}) \\pm 1.4~(\\mathrm{sys}))\\%$$, in good agreement with the Monte Carlo reconstruction efficiency $$\\epsilon_{\\mathrm{MC}} = (97.4\\pm0.1)\\%$$. This analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag $$\\approx80\\%$$ of the cosmic rays passing through the MicroBooNE detector.« less

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

DOE PAGES

Acciarri, R.; Adams, C.; An, R.; ...

2017-12-20

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. In this paper, we present a method of using an external 0.5 m (L) × 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersectingmore » different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to be ϵ data=(97.1±0.1 (stat) ± 1.4 (sys))%, in good agreement with the Monte Carlo reconstruction efficiency ϵ MC = (97.4±0.1)%. In conclusion, this analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag ≈80% of the cosmic rays passing through the MicroBooNE detector.« less

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

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

Acciarri, R.; Adams, C.; An, R.

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. In this paper, we present a method of using an external 0.5 m (L) × 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersectingmore » different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to be ϵ data=(97.1±0.1 (stat) ± 1.4 (sys))%, in good agreement with the Monte Carlo reconstruction efficiency ϵ MC = (97.4±0.1)%. In conclusion, this analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag ≈80% of the cosmic rays passing through the MicroBooNE detector.« less

Measurement of cosmic-ray reconstruction efficiencies in the MicroBooNE LArTPC using a small external cosmic-ray counter

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

Acciarri, R.; et al.

2017-07-31

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. We present a method of using an external 0.5 m (L) x 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersecting different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to bemore » $$\\epsilon_{\\mathrm{data}}=(97.1\\pm0.1~(\\mathrm{stat}) \\pm 1.4~(\\mathrm{sys}))\\%$$, in good agreement with the Monte Carlo reconstruction efficiency $$\\epsilon_{\\mathrm{MC}} = (97.4\\pm0.1)\\%$$. This analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag $$\\approx80\\%$$ of the cosmic rays passing through the MicroBooNE detector.« less

Three-dimensional rotational micro-angiography

NASA Astrophysics Data System (ADS)

Patel, Vikas

Computed tomography (CT) is state-of-the-art for 3D imaging in which images are acquired about the patient and are used to reconstruct the data. But the commercial CT systems suffer from low spatial resolution (0.5-2 lp/mm). Micro-CT (microCT) systems have high resolution 3D reconstruction (>10 lp/mm), but are currently limited to small objects, e.g., small animals. To achieve artifact free reconstructions, geometric calibration of the rotating-object cone-beam microCT (CBmicroCT) system is performed using new techniques that use only the projection images of the object, i.e., no calibration objects are required. Translations (up to 0.2 mm) occurring during the acquisition in the horizontal direction are detected, quantified, and corrected based on sinogram analysis. The parameters describing the physical axis of rotation determined using our image-based method (aligning anti-posed images) agree well (within 0.1 mm and 0.3 degrees) with those determined using other techniques that use calibration objects. Geometric calibrations of the rotational angiography (RA) systems (clinical cone-beam CT systems with fluoroscopic capabilities provided by flat-panel detectors (FPD)) are performed using a simple single projection technique (SPT), which aligns a known 3D model of a calibration phantom with the projection data. The calibration parameters obtained by the SPT are found to be reproducible (angles within 0.2° and x- and y-translations less than 2 mm) for over 7 months. The spatial resolution of the RA systems is found to be virtually unaffected by such small geometric variations. Finally, using our understanding of the geometric calibrations, we have developed methods to combine relatively low-resolution RA acquisitions (2-3 lp/mm) with high resolution microCT acquisitions (using a high-resolution micro-angiographic fluoroscope (MAF) attached to the RA gantry) to produce the first-ever 3D rotational micro-angiography (3D-RmicroA) system on a clinical gantry. Images of a rabbit with a coronary stent placed in an artery were obtained and reconstructed. To eliminate artifacts due to image truncation, lower-dose (compared to the MAF acquisition) full-FOV (FFOV) FPD RA sequences are also obtained. To ensure high-quality high-resolution reconstruction, the high-resolution images from the MAF are aligned spatially with the lower-dose FPD images (average correlation coefficient before and after alignment: 0.65 and 0.97 respectively), and the pixel values in the FPD image data are scaled (using linear regression) to match those of the MAF. Greater details without any visible truncation artifacts are seen in 3D RmicroA (MAF-FPD) images than in those of the FPD alone. The FWHM of line profiles of stent struts (100 micron diameter) are approximately 192 +/- 21 and 313 +/- 38 microns for the 3D RmicroA and FPD data, respectively. Thus, with the RmicroA system, we have essentially developed a high resolution CBmicroCT system for clinical use.

Under-response of a PTW-60019 microDiamond detector in the Bragg peak of a 62 MeV/n carbon ion beam

NASA Astrophysics Data System (ADS)

Rossomme, S.; Hopfgartner, J.; Vynckier, S.; Palmans, H.

2016-06-01

To investigate the linear energy transfer (LET) dependence of the response of a PTW-60019 Freiburg microDiamond detector, its response was compared to the response of a plane-parallel Markus chamber in a 62 MeV/n mono-energetic carbon ion beam. Results obtained with two different experimental setups are in agreement. As recommended by IAEA TRS-398, the response of the Markus chamber was corrected for temperature, pressure, polarity effects and ion recombination. No correction was applied to the response of the microDiamond detector. The ratio of the response of the Markus chamber to the response of the microDiamond is close to unity in the plateau region. In the Bragg peak region, a significant increase of the ratio is observed, which increases to 1.2 in the distal edge region. Results indicate a correlation between the under-response of the microDiamond detector and high LET values. The combined relative standard uncertainty of the results is estimated to be 2.38% in the plateau region and 12% in the distal edge region. These values are dominated by the uncertainty of alignment in the non-uniform beam and the uncertainty of range determination.

Interfacing Issues in Microcooling of Optical Detectors in Space Applications

NASA Astrophysics Data System (ADS)

Derking, J. H.; ter Brake, H. J. M.; Linder, M.; Rogalla, H.

2010-04-01

Miniature Joule-Thomson coolers were developed at the University of Twente and are able to cool to 100 K with a typical cooling power of 10 to 20 mW. These coolers have a high potential for space applications in cooling small optical detectors for future earth observation and science missions. Under contract of the European Space Agency, we investigate on-chip detector cooling for the temperature range 70 K-250 K. To identify the detectors that can be cooled by a JT microcooler, a literature survey was performed. Following this survey, we selected a micro digital CMOS image sensor. A conceptual design of this cooler-sensor system is made. Among various techniques, indium soldering and silver paint are chosen for the bonding of the silicon sensor to the glass microcooler. Electrical connections from the sensor to the outside will be realized by structuring them in a thin layer of gold that is sputtered on the outside of the cooler to minimize the radiative heat load. For the electrical connections between the sensor and the structured leads, aluminum or gold bond wires will be used.

Determination of output factor for 6 MV small photon beam: comparison between Monte Carlo simulation technique and microDiamond detector

NASA Astrophysics Data System (ADS)

Krongkietlearts, K.; Tangboonduangjit, P.; Paisangittisakul, N.

2016-03-01

In order to improve the life's quality for a cancer patient, the radiation techniques are constantly evolving. Especially, the two modern techniques which are intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are quite promising. They comprise of many small beam sizes (beamlets) with various intensities to achieve the intended radiation dose to the tumor and minimal dose to the nearby normal tissue. The study investigates whether the microDiamond detector (PTW manufacturer), a synthetic single crystal diamond detector, is suitable for small field output factor measurement. The results were compared with those measured by the stereotactic field detector (SFD) and the Monte Carlo simulation (EGSnrc/BEAMnrc/DOSXYZ). The calibration of Monte Carlo simulation was done using the percentage depth dose and dose profile measured by the photon field detector (PFD) of the 10×10 cm2 field size with 100 cm SSD. Comparison of the values obtained from the calculations and measurements are consistent, no more than 1% difference. The output factors obtained from the microDiamond detector have been compared with those of SFD and Monte Carlo simulation, the results demonstrate the percentage difference of less than 2%.

Generalized two-dimensional (2D) linear system analysis metrics (GMTF, GDQE) for digital radiography systems including the effect of focal spot, magnification, scatter, and detector characteristics.

PubMed

Jain, Amit; Kuhls-Gilcrist, Andrew T; Gupta, Sandesh K; Bednarek, Daniel R; Rudin, Stephen

2010-03-01

The MTF, NNPS, and DQE are standard linear system metrics used to characterize intrinsic detector performance. To evaluate total system performance for actual clinical conditions, generalized linear system metrics (GMTF, GNNPS and GDQE) that include the effect of the focal spot distribution, scattered radiation, and geometric unsharpness are more meaningful and appropriate. In this study, a two-dimensional (2D) generalized linear system analysis was carried out for a standard flat panel detector (FPD) (194-micron pixel pitch and 600-micron thick CsI) and a newly-developed, high-resolution, micro-angiographic fluoroscope (MAF) (35-micron pixel pitch and 300-micron thick CsI). Realistic clinical parameters and x-ray spectra were used. The 2D detector MTFs were calculated using the new Noise Response method and slanted edge method and 2D focal spot distribution measurements were done using a pin-hole assembly. The scatter fraction, generated for a uniform head equivalent phantom, was measured and the scatter MTF was simulated with a theoretical model. Different magnifications and scatter fractions were used to estimate the 2D GMTF, GNNPS and GDQE for both detectors. Results show spatial non-isotropy for the 2D generalized metrics which provide a quantitative description of the performance of the complete imaging system for both detectors. This generalized analysis demonstrated that the MAF and FPD have similar capabilities at lower spatial frequencies, but that the MAF has superior performance over the FPD at higher frequencies even when considering focal spot blurring and scatter. This 2D generalized performance analysis is a valuable tool to evaluate total system capabilities and to enable optimized design for specific imaging tasks.

Demonstration of the CDMA-mode CAOS smart camera.

PubMed

Riza, Nabeel A; Mazhar, Mohsin A

2017-12-11

Demonstrated is the code division multiple access (CDMA)-mode coded access optical sensor (CAOS) smart camera suited for bright target scenarios. Deploying a silicon CMOS sensor and a silicon point detector within a digital micro-mirror device (DMD)-based spatially isolating hybrid camera design, this smart imager first engages the DMD starring mode with a controlled factor of 200 high optical attenuation of the scene irradiance to provide a classic unsaturated CMOS sensor-based image for target intelligence gathering. Next, this CMOS sensor provided image data is used to acquire a focused zone more robust un-attenuated true target image using the time-modulated CDMA-mode of the CAOS camera. Using four different bright light test target scenes, successfully demonstrated is a proof-of-concept visible band CAOS smart camera operating in the CDMA-mode using up-to 4096 bits length Walsh design CAOS pixel codes with a maximum 10 KHz code bit rate giving a 0.4096 seconds CAOS frame acquisition time. A 16-bit analog-to-digital converter (ADC) with time domain correlation digital signal processing (DSP) generates the CDMA-mode images with a 3600 CAOS pixel count and a best spatial resolution of one micro-mirror square pixel size of 13.68 μm side. The CDMA-mode of the CAOS smart camera is suited for applications where robust high dynamic range (DR) imaging is needed for un-attenuated un-spoiled bright light spectrally diverse targets.

Ionization Electron Signal Processing in Single Phase LArTPCs II. Data/Simulation Comparison and Performance in MicroBooNE

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

Adams, C.; et al.

The single-phase liquid argon time projection chamber (LArTPC) provides a large amount of detailed information in the form of fine-grained drifted ionization charge from particle traces. To fully utilize this information, the deposited charge must be accurately extracted from the raw digitized waveforms via a robust signal processing chain. Enabled by the ultra-low noise levels associated with cryogenic electronics in the MicroBooNE detector, the precise extraction of ionization charge from the induction wire planes in a single-phase LArTPC is qualitatively demonstrated on MicroBooNE data with event display images, and quantitatively demonstrated via waveform-level and track-level metrics. Improved performance of inductionmore » plane calorimetry is demonstrated through the agreement of extracted ionization charge measurements across different wire planes for various event topologies. In addition to the comprehensive waveform-level comparison of data and simulation, a calibration of the cryogenic electronics response is presented and solutions to various MicroBooNE-specific TPC issues are discussed. This work presents an important improvement in LArTPC signal processing, the foundation of reconstruction and therefore physics analyses in MicroBooNE.« less

Dosimetry of cone-defined stereotactic radiosurgery fields with a commercial synthetic diamond detector.

PubMed

Morales, Johnny E; Crowe, Scott B; Hill, Robin; Freeman, Nigel; Trapp, J V

2014-11-01

Small field x-ray beam dosimetry is difficult due to lack of lateral electronic equilibrium, source occlusion, high dose gradients, and detector volume averaging. Currently, there is no single definitive detector recommended for small field dosimetry. The objective of this work was to evaluate the performance of a new commercial synthetic diamond detector, namely, the PTW 60019 microDiamond, for the dosimetry of small x-ray fields as used in stereotactic radiosurgery (SRS). Small field sizes were defined by BrainLAB circular cones (4-30 mm diameter) on a Novalis Trilogy linear accelerator and using the 6 MV SRS x-ray beam mode for all measurements. Percentage depth doses (PDDs) were measured and compared to an IBA SFD and a PTW 60012 E diode. Cross profiles were measured and compared to an IBA SFD diode. Field factors, ΩQclin,Qmsr (fclin,fmsr) , were calculated by Monte Carlo methods using BEAMnrc and correction factors, kQclin,Qmsr (fclin,fmsr) , were derived for the PTW 60019 microDiamond detector. For the small fields of 4-30 mm diameter, there were dose differences in the PDDs of up to 1.5% when compared to an IBA SFD and PTW 60012 E diode detector. For the cross profile measurements the penumbra values varied, depending upon the orientation of the detector. The field factors, ΩQclin,Qmsr (fclin,fmsr) , were calculated for these field diameters at a depth of 1.4 cm in water and they were within 2.7% of published values for a similar linear accelerator. The corrections factors, kQclin,Qmsr (fclin,fmsr) , were derived for the PTW 60019 microDiamond detector. The authors conclude that the new PTW 60019 microDiamond detector is generally suitable for relative dosimetry in small 6 MV SRS beams for a Novalis Trilogy linear equipped with circular cones.

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

Leng, Shuai; Yu, Lifeng; Wang, Jia

Purpose: Our purpose was to reduce image noise in spectral CT by exploiting data redundancies in the energy domain to allow flexible selection of the number, width, and location of the energy bins. Methods: Using a variety of spectral CT imaging methods, conventional filtered backprojection (FBP) reconstructions were performed and resulting images were compared to those processed using a Local HighlY constrained backPRojection Reconstruction (HYPR-LR) algorithm. The mean and standard deviation of CT numbers were measured within regions of interest (ROIs), and results were compared between FBP and HYPR-LR. For these comparisons, the following spectral CT imaging methods were used:(i)more » numerical simulations based on a photon-counting, detector-based CT system, (ii) a photon-counting, detector-based micro CT system using rubidium and potassium chloride solutions, (iii) a commercial CT system equipped with integrating detectors utilizing tube potentials of 80, 100, 120, and 140 kV, and (iv) a clinical dual-energy CT examination. The effects of tube energy and energy bin width were evaluated appropriate to each CT system. Results: The mean CT number in each ROI was unchanged between FBP and HYPR-LR images for each of the spectral CT imaging scenarios, irrespective of bin width or tube potential. However, image noise, as represented by the standard deviation of CT numbers in each ROI, was reduced by 36%-76%. In all scenarios, image noise after HYPR-LR algorithm was similar to that of composite images, which used all available photons. No difference in spatial resolution was observed between HYPR-LR processing and FBP. Dual energy patient data processed using HYPR-LR demonstrated reduced noise in the individual, low- and high-energy images, as well as in the material-specific basis images. Conclusions: Noise reduction can be accomplished for spectral CT by exploiting data redundancies in the energy domain. HYPR-LR is a robust method for reducing image noise in a variety of spectral CT imaging systems without losing spatial resolution or CT number accuracy. This method improves the flexibility to select energy bins in the manner that optimizes material identification and separation without paying the penalty of increased image noise or its corollary, increased patient dose.« less

Physical characterization of a scanning photon counting digital mammography system based on Si-strip detectors.

PubMed

Aslund, Magnus; Cederström, Björn; Lundqvist, Mats; Danielsson, Mats

2007-06-01

The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 microm and the field of view 24 x 26 cm2. The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 microGy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anode-filter combination with an added 2 mm Al filtration.

Enhanced infrared transmission through subwavelength hole arrays in a thin gold film mounted with dielectric micro-domes

NASA Astrophysics Data System (ADS)

Kumar, Raghwendra; Ramakrishna, S. Anantha

2018-04-01

Dielectric micro-domes were mounted on the subwavelength holes of a periodically perforated gold film such that a lens-like micro-dome covers each hole. In comparison to the extraordinary transmission through an array of bare holes in the gold film, this structure showed a further enhanced transmission over a larger range of incident angles with much larger bandwidth at mid-wave infrared wavelengths (3-4.5~μ m). The structure was fabricated using laser interference lithography, a novel back-exposure with an ultra-violet laser, and lift-off process that left behind the micro-domes of SU-8, covering each of the holes in the gold film. The measured transmittance of these perforated gold films, with and without the micro-domes, was verified by electromagnetic wave simulations. The enhanced transmittance arises from the scattered electromagnetic fields of the micro-domes, which couple the incident light efficiently via the scattered near-fields into the waveguide modes of holes in the plasmonic film. The increased transmittance and the highly enhanced and localized near-fields can be used to enhance the photo-response of infrared detectors over relevant bands, for example, the 3-4.5~μ m band that is used for thermal imaging applications.

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

Barrett, J C; Karmanos Cancer Institute McLaren-Macomb, Clinton Township, MI; Knill, C

Purpose: To determine small field correction factors for PTW’s microDiamond detector in Elekta’s Gamma Knife Model-C unit. These factors allow the microDiamond to be used in QA measurements of output factors in the Gamma Knife Model-C; additionally, the results also contribute to the discussion on the water equivalence of the relatively-new microDiamond detector and its overall effectiveness in small field applications. Methods: The small field correction factors were calculated as k correction factors according to the Alfonso formalism. An MC model of the Gamma Knife and microDiamond was built with the EGSnrc code system, using BEAMnrc and DOSRZnrc user codes.more » Validation of the model was accomplished by simulating field output factors and measurement ratios for an available ABS plastic phantom and then comparing simulated results to film measurements, detector measurements, and treatment planning system (TPS) data. Once validated, the final k factors were determined by applying the model to a more waterlike solid water phantom. Results: During validation, all MC methods agreed with experiment within the stated uncertainties: MC determined field output factors agreed within 0.6% of the TPS and 1.4% of film; and MC simulated measurement ratios matched physically measured ratios within 1%. The final k correction factors for the PTW microDiamond in the solid water phantom approached unity to within 0.4%±1.7% for all the helmet sizes except the 4 mm; the 4 mm helmet size over-responded by 3.2%±1.7%, resulting in a k factor of 0.969. Conclusion: Similar to what has been found in the Gamma Knife Perfexion, the PTW microDiamond requires little to no corrections except for the smallest 4 mm field. The over-response can be corrected via the Alfonso formalism using the correction factors determined in this work. Using the MC calculated correction factors, the PTW microDiamond detector is an effective dosimeter in all available helmet sizes. The authors would like to thank PTW (Friedberg, Germany) for providing the PTW microDiamond detector for this research.« less

A time-based front-end ASIC for the silicon micro strip sensors of the bar PANDA Micro Vertex Detector

NASA Astrophysics Data System (ADS)

Di Pietro, V.; Brinkmann, K.-Th.; Riccardi, A.; Ritman, J.; Rivetti, A.; Rolo, M. D.; Stockmanns, T.; Zambanini, A.

2016-03-01

The bar PANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (bar PANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

WE-AB-207A-01: BEST IN PHYSICS (IMAGING): High-Resolution Cone-Beam CT of the Extremities and Cancellous Bone Architecture with a CMOS Detector

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

Cao, Q; Brehler, M; Sisniega, A

Purpose: Extremity cone-beam CT (CBCT) with an amorphous silicon (aSi) flat-panel detector (FPD) provides low-dose volumetric imaging with high spatial resolution. We investigate the performance of the newer complementary metal-oxide semiconductor (CMOS) detectors to enhance resolution of extremities CBCT to ∼0.1 mm, enabling morphological analysis of trabecular bone. Quantitative in-vivo imaging of bone microarchitecture could present an important advance for osteoporosis and osteoarthritis diagnosis and therapy assessment. Methods: Cascaded systems models of CMOS- and FPD-based extremities CBCT were implemented. Performance was compared for a range of pixel sizes (0.05–0.4 mm), focal spot sizes (0.3–0.6 FS), and x-ray techniques (0.05–0.8 mAs/projection)more » using detectability of high-, low-, and all-frequency tasks for a nonprewhitening observer. Test-bench implementation of CMOS-based extremity CBCT involved a Teledyne DALSA Xineos3030HR detector with 0.099 mm pixels and a compact rotating anode x-ray source with 0.3 FS (IMD RTM37). Metrics of bone morphology obtained using CMOS-based CBCT were compared in cadaveric specimens to FPD-based system using a Varian PaxScan4030 (0.194 mm pixels). Results: Finer pixel size and reduced electronic noise for CMOS (136 e compared to 2000 e for FPD) resulted in ∼1.9× increase in detectability for high-frequency tasks and ∼1.1× increase for all-frequency tasks. Incorporation of the new x-ray source with reduced focal spot size (0.3 FS vs. 0.5 FS used on current extremities CBCT) improved detectability for CMOS-based CBCT by ∼1.7× for high-frequency tasks. Compared to FPD CBCT, the CMOS detector yielded improved agreement with micro-CT in measurements of trabecular thickness (∼1.7× reduction in relative error), bone volume (∼1.5× reduction), and trabecular spacing (∼3.5× reduction). Conclusion: Imaging performance modelling and experimentation indicate substantial improvements for high-frequency imaging tasks through adoption of the CMOS detector and small FS x-ray source, motivating the use of these components in a new system for quantitative in-vivo imaging of trabecular bone. Financial Support: US NIH grant R01EB018896. Qian Cao is a Howard Hughes Medical Institute International Student Research Fellow. Disclosures: W Zbijewski, J Siewerdsen and A Sisniega receive research funding from Carestream Health.« less

Innovative optronics for the new PUMA tank

NASA Astrophysics Data System (ADS)

Fritze, J.; Münzberg, M.; Schlemmer, H.

2010-04-01

The new PUMA tank is equipped with a fully stabilized 360° periscope. The thermal imager in the periscope is identical to the imager in the gunner sight. All optronic images of the cameras can be fed on every electronic display within the tank. The thermal imagers operate with a long wave 384x288 MCT starring focal plane array. The high quantum efficiency of MCT provides low NETD values at short integration times. The thermal imager has an image resolution of 768x576 pixels by means of a micro scanner. The MCT detector operates at high temperatures above 75K with high stability in noise and correctibility and offers high reliability (MTTF) values for the complete camera in a very compact design. The paper discusses the principle and functionality of the optronic combination of direct view optical channel, thermal imager and visible camera and discusses in detail the performances of the subcomponents with respect to demands for new tank applications.

SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

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

Vijayan, S; Rana, V; Nagesh, S Setlur

Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detectormore » was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873.« less

Programmable spectral engine design of hyperspectral image projectors based on digital micro-mirror device (DMD)

NASA Astrophysics Data System (ADS)

Wang, Xicheng; Gao, Jiaobo; Wu, Jianghui; Li, Jianjun; Cheng, Hongliang

2017-02-01

Recently, hyperspectral image projectors (HIP) have been developed in the field of remote sensing. For the advanced performance of system-level validation, target detection and hyperspectral image calibration, HIP has great possibility of development in military, medicine, commercial and so on. HIP is based on the digital micro-mirror device (DMD) and projection technology, which is capable to project arbitrary programmable spectra (controlled by PC) into the each pixel of the IUT1 (instrument under test), such that the projected image could simulate realistic scenes that hyperspectral image could be measured during its use and enable system-level performance testing and validation. In this paper, we built a visible hyperspectral image projector also called the visible target simulator with double DMDs, which the first DMD is used to product the selected monochromatic light from the wavelength of 410 to 720 um, and the light come to the other one. Then we use computer to load image of realistic scenes to the second DMD, so that the target condition and background could be project by the second DMD with the selected monochromatic light. The target condition can be simulated and the experiment could be controlled and repeated in the lab, making the detector instrument could be tested in the lab. For the moment, we make the focus on the spectral engine design include the optical system, research of DMD programmable spectrum and the spectral resolution of the selected spectrum. The detail is shown.

Scatter and beam hardening reduction in industrial computed tomography using photon counting detectors

NASA Astrophysics Data System (ADS)

Schumacher, David; Sharma, Ravi; Grager, Jan-Carl; Schrapp, Michael

2018-07-01

Photon counting detectors (PCD) offer new possibilities for x-ray micro computed tomography (CT) in the field of non-destructive testing. For large and/or dense objects with high atomic numbers the problem of scattered radiation and beam hardening severely influences the image quality. This work shows that using an energy discriminating PCD based on CdTe allows to address these problems by intrinsically reducing both the influence of scattering and beam hardening. Based on 2D-radiographic measurements it is shown that by energy thresholding the influence of scattered radiation can be reduced by up to in case of a PCD compared to a conventional energy-integrating detector (EID). To demonstrate the capabilities of a PCD in reducing beam hardening, cupping artefacts are analyzed quantitatively. The PCD results show that the higher the energy threshold is set, the lower the cupping effect emerges. But since numerous beam hardening correction algorithms exist, the results of the PCD are compared to EID results corrected by common techniques. Nevertheless, the highest energy thresholds yield lower cupping artefacts than any of the applied correction algorithms. As an example of a potential industrial CT application, a turbine blade is investigated by CT. The inner structure of the turbine blade allows for comparing the image quality between PCD and EID in terms of absolute contrast, as well as normalized signal-to-noise and contrast-to-noise ratio. Where the absolute contrast can be improved by raising the energy thresholds of the PCD, it is found that due to lower statistics the normalized contrast-to-noise-ratio could not be improved compared to the EID. These results might change to the contrary when discarding pre-filtering of the x-ray spectra and thus allowing more low-energy photons to reach the detectors. Despite still being in the early phase in technological progress, PCDs already allow to improve CT image quality compared to conventional detectors in terms of scatter and beam hardening reduction.

Development of the micro pixel chamber based on MEMS technology

NASA Astrophysics Data System (ADS)

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

2018-02-01

Micro pixel chambers (μ-PIC) are gaseous two-dimensional imaging detectors originally manufactured using printed circuit board (PCB) technology. They are used in MeV gamma-ray astronomy, medicalimaging, neutron imaging, the search for dark matter, and dose monitoring. The position resolution of the present μ-PIC is approximately 120 μm (RMS), however some applications require a fine position resolution of less than 100 μm. To this end, we have started to develop a μ-PIC based on micro electro mechanical system (MEMS) technology, which provides better manufacturing accuracy than PCB technology. Our simulation predicted the gains of MEMS μ-PICs to be twice those of PCB μ-PICs at the same anode voltage. We manufactured two MEMS μ-PICs and tested them to study their behavior. In these experiments, we successfully operated the fabricatedMEMS μ-PICs and we achieved a maximum gain of approximately 7×103 and collected their energy spectra under irradiation of X-rays from 55Fe. However, the measured gains of the MEMS μ-PICs were less than half of the values predicted in the simulations. We postulated that the gains of the MEMS μ-PICs are diminished by the effect of the silicon used as a semiconducting substrate.

SCAPS, a two-dimensional ion detector for mass spectrometer

NASA Astrophysics Data System (ADS)

Yurimoto, Hisayoshi

2014-05-01

Faraday Cup (FC) and electron multiplier (EM) are of the most popular ion detector for mass spectrometer. FC is used for high-count-rate ion measurements and EM can detect from single ion. However, FC is difficult to detect lower intensities less than kilo-cps, and EM loses ion counts higher than Mega-cps. Thus, FC and EM are used complementary each other, but they both belong to zero-dimensional detector. On the other hand, micro channel plate (MCP) is a popular ion signal amplifier with two-dimensional capability, but additional detection system must be attached to detect the amplified signals. Two-dimensional readout for the MCP signals, however, have not achieve the level of FC and EM systems. A stacked CMOS active pixel sensor (SCAPS) has been developed to detect two-dimensional ion variations for a spatial area using semiconductor technology [1-8]. The SCAPS is an integrated type multi-detector, which is different from EM and FC, and is composed of more than 500×500 pixels (micro-detectors) for imaging of cm-area with a pixel of less than 20 µm in square. The SCAPS can be detected from single ion to 100 kilo-count ions per one pixel. Thus, SCAPS can be accumulated up to several giga-count ions for total pixels, i.e. for total imaging area. The SCAPS has been applied to stigmatic ion optics of secondary ion mass spectrometer, as a detector of isotope microscope [9]. The isotope microscope has capabilities of quantitative isotope images of hundred-micrometer area on a sample with sub-micrometer resolution and permil precision, and of two-dimensional mass spectrum on cm-scale of mass dispersion plane of a sector magnet with ten-micrometer resolution. The performance has been applied to two-dimensional isotope spatial distribution for mainly hydrogen, carbon, nitrogen and oxygen of natural (extra-terrestrial and terrestrial) samples and samples simulated natural processes [e.g. 10-17]. References: [1] Matsumoto, K., et al. (1993) IEEE Trans. Electron Dev. 40, 82-85. [2] Takayanagi et al. (1999) Proc. 1999 IEEE workshop on Charge-Coupled Devices and Advanced Image Sensors, 159-162. [3] Kunihiro et al. (2001) Nucl. Instrum. Methods Phys. Res. Sec. A 470, 512-519. [4] Nagashima et al. (2001) Surface Interface Anal. 31, 131-137. [5] Takayanagi et al. (2003) IEEE Trans. Electron Dev. 50, 70- 76. [6] Sakamoto and Yurimoto (2006) Surface Interface Anal. 38, 1760-1762. [7] Yamamoto et al. (2010) Surface Interface Anal. 42, 1603-1605. [8] Sakamoto et al. (2012) Jpn. J. Appl. Phys. 51, 076701. [9] Yurimoto et al. (2003) Appl. Surf. Sci. 203-204, 793-797. [10] Nagashima et al. (2004) Nature 428, 921-924. [11] Kunihiro et al. (2005) Geochim. Cosmochim. Acta 69, 763-773. [12] Nakamura et al. (2005) Geology 33, 829-832. [13] Sakamoto et al. (2007) Science 317, 231-233. [14] Greenwood et al. (2008) Geophys. Res. Lett., 35, L05203. [15] Greenwood et al. (2011) Nature Geoscience 4, 79-82. [16] Park et al. (2012) Meteorit. Planet. Sci. 47, 2070-2083. [17] Hashiguchi et al. (2013) Geochim. Cosmochim. Acta. 122, 306-323.

Renal stone characterization using high resolution imaging mode on a photon counting detector CT system

NASA Astrophysics Data System (ADS)

Ferrero, A.; Gutjahr, R.; Henning, A.; Kappler, S.; Halaweish, A.; Abdurakhimova, D.; Peterson, Z.; Montoya, J.; Leng, S.; McCollough, C.

2017-03-01

In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm x 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same subelements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

Renal Stone Characterization using High Resolution Imaging Mode on a Photon Counting Detector CT System.

PubMed

Ferrero, A; Gutjahr, R; Henning, A; Kappler, S; Halaweish, A; Abdurakhimova, D; Peterson, Z; Montoya, J; Leng, S; McCollough, C

2017-03-09

In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm × 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same sub-elements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

A prototype table-top inverse-geometry volumetric CT system.

PubMed

Schmidt, Taly Gilat; Star-Lack, Josh; Bennett, N Robert; Mazin, Samuel R; Solomon, Edward G; Fahrig, Rebecca; Pelc, Norbert J

2006-06-01

A table-top volumetric CT system has been implemented that is able to image a 5-cm-thick volume in one circular scan with no cone-beam artifacts. The prototype inverse-geometry CT (IGCT) scanner consists of a large-area, scanned x-ray source and a detector array that is smaller in the transverse direction. The IGCT geometry provides sufficient volumetric sampling because the source and detector have the same axial, or slice direction, extent. This paper describes the implementation of the table-top IGCT scanner, which is based on the NexRay Scanning-Beam Digital X-ray system (NexRay, Inc., Los Gatos, CA) and an investigation of the system performance. The alignment and flat-field calibration procedures are described, along with a summary of the reconstruction algorithm. The resolution and noise performance of the prototype IGCT system are studied through experiments and further supported by analytical predictions and simulations. To study the presence of cone-beam artifacts, a "Defrise" phantom was scanned on both the prototype IGCT scanner and a micro CT system with a +/-5 cone angle for a 4.5-cm volume thickness. Images of inner ear specimens are presented and compared to those from clinical CT systems. Results showed that the prototype IGCT system has a 0.25-mm isotropic resolution and that noise comparable to that from a clinical scanner with equivalent spatial resolution is achievable. The measured MTF and noise values agreed reasonably well with theoretical predictions and computer simulations. The IGCT system was able to faithfully reconstruct the laminated pattern of the Defrise phantom while the micro CT system suffered severe cone-beam artifacts for the same object. The inner ear acquisition verified that the IGCT system can image a complex anatomical object, and the resulting images exhibited more high-resolution details than the clinical CT acquisition. Overall, the successful implementation of the prototype system supports the IGCT concept for single-rotation volumetric scanning free from cone-beam artifacts.

Performance of a PTW 60019 microDiamond detector in a 1.5 T MRI-linac

NASA Astrophysics Data System (ADS)

Woodings, S. J.; Wolthaus, J. W. H.; van Asselen, B.; de Vries, J. H. W.; Kok, J. G. M.; Lagendijk, J. J. W.; Raaymakers, B. W.

2018-03-01

Accurate small-field dosimetry is critical for a magnetic resonance linac (MRI-linac). The PTW 60019 microDiamond is close to an ideal detector for small field dosimetry due to its small physical size, high signal-to-noise ratio and approximate water equivalence. It is important to fully characterise the performance of the detector in a 1.5 T magnetic field prior to its use for MRI-linac commissioning and quality assurance. Standard techniques of detector testing have been implemented, or adapted where necessary to suit the capabilities of the MRI-linac. Detector warmup, constancy, dose linearity, dose rate linearity, field size dependence and leakage were within tolerance. Measurements with the detector were consistent with ion chamber measurements for medium sized fields. The effective point of measurement of the detector when used within a 1.5 T magnetic field was determined to be 0.80 ± 0.23 mm below the top surface of the device, consistent with the existing vendor recommendation and alignment mark at 1.0 mm. The angular dependence was assessed. Variations of up to 9.7% were observed, which are significantly greater than in a 0 T environment. Within the expected range of use, the maximum effect is approximately 0.6% which is within tolerance. However for large beams within a magnetic field, the divergence and consequent variation in angle of photon incidence means that the microDiamond would not be ideal for characterising the profiles and it would not be suitable for determining large-field beam parameters such as symmetry. It would also require a correction factor prior to use for patient-specific QA measurements where radiation is delivered from different gantry angles. The results of this study demonstrate that the PTW 60019 microDiamond detector is suitable for measuring small radiation fields within a 1.5 T magnetic field and thus is suitable for use in MRI-linac commissioning and quality assurance.

Performance of a PTW 60019 microDiamond detector in a 1.5 T MRI-linac.

PubMed

Woodings, S J; Wolthaus, J W H; van Asselen, B; de Vries, J H W; Kok, J G M; Lagendijk, J J W; Raaymakers, B W

2018-03-08

Accurate small-field dosimetry is critical for a magnetic resonance linac (MRI-linac). The PTW 60019 microDiamond is close to an ideal detector for small field dosimetry due to its small physical size, high signal-to-noise ratio and approximate water equivalence. It is important to fully characterise the performance of the detector in a 1.5 T magnetic field prior to its use for MRI-linac commissioning and quality assurance. Standard techniques of detector testing have been implemented, or adapted where necessary to suit the capabilities of the MRI-linac. Detector warmup, constancy, dose linearity, dose rate linearity, field size dependence and leakage were within tolerance. Measurements with the detector were consistent with ion chamber measurements for medium sized fields. The effective point of measurement of the detector when used within a 1.5 T magnetic field was determined to be 0.80 ± 0.23 mm below the top surface of the device, consistent with the existing vendor recommendation and alignment mark at 1.0 mm. The angular dependence was assessed. Variations of up to 9.7% were observed, which are significantly greater than in a 0 T environment. Within the expected range of use, the maximum effect is approximately 0.6% which is within tolerance. However for large beams within a magnetic field, the divergence and consequent variation in angle of photon incidence means that the microDiamond would not be ideal for characterising the profiles and it would not be suitable for determining large-field beam parameters such as symmetry. It would also require a correction factor prior to use for patient-specific QA measurements where radiation is delivered from different gantry angles. The results of this study demonstrate that the PTW 60019 microDiamond detector is suitable for measuring small radiation fields within a 1.5 T magnetic field and thus is suitable for use in MRI-linac commissioning and quality assurance.

Optical MEMS for Earth observation

NASA Astrophysics Data System (ADS)

Liotard, Arnaud; Viard, Thierry; Noell, Wilfried; Zamkotsian, Frédéric; Freire, Marco; Guldimann, Benedikt; Kraft, Stefan

2017-11-01

Due to the relatively large number of optical Earth Observation missions at ESA, this area is interesting for new space technology developments. In addition to their compactness, scalability and specific task customization, optical MEMS could generate new functions not available with current technologies and are thus candidates for the design of future space instruments. Most mature components for space applications are the digital mirror arrays, the micro-deformable mirrors, the programmable micro diffraction gratings and tiltable micromirrors. A first selection of market-pull and techno-push concepts is done. In addition, some concepts are coming from outside Earth Observation. Finally two concepts are more deeply analyzed. The first concept is a programmable slit for straylight control for space spectro-imagers. This instrument is a push-broom spectroimager for which some images cannot be exploited because of bright sources in the field-of-view. The proposed concept consists in replacing the current entrance spectrometer slit by an active row of micro-mirrors. The MEMS will permit to dynamically remove the bright sources and then to obtain a field-of-view with an optically enhanced signal-to-noise ratio. The second concept is a push-broom imager for which the acquired spectrum can be tuned by optical MEMS. This system is composed of two diffractive elements and a digital mirror array. The first diffractive element spreads the spectrum. A micromirror array is set at the location of the spectral focal plane. By putting the micro-mirrors ON or OFF, we can select parts of field-of-view or spectrum. The second diffractive element then recombines the light on a push-broom detector. Dichroics filters, strip filter, band-pass filter could be replaced by a unique instrument.

Engineering and performance (NEMA and animal) of a lower-cost higher-resolution animal PET/CT scanner using photomultiplier-quadrant-sharing detectors.

PubMed

Wong, Wai-Hoi; Li, Hongdi; Baghaei, Hossain; Zhang, Yuxuan; Ramirez, Rocio A; Liu, Shitao; Wang, Chao; An, Shaohui

2012-11-01

The dedicated murine PET (MuPET) scanner is a high-resolution, high-sensitivity, and low-cost preclinical PET camera designed and manufactured at our laboratory. In this article, we report its performance according to the NU 4-2008 standards of the National Electrical Manufacturers Association (NEMA). We also report the results of additional phantom and mouse studies. The MuPET scanner, which is integrated with a CT camera, is based on the photomultiplier-quadrant-sharing concept and comprises 180 blocks of 13 × 13 lutetium yttrium oxyorthosilicate crystals (1.24 × 1.4 × 9.5 mm(3)) and 210 low-cost 19-mm photomultipliers. The camera has 78 detector rings, with an 11.6-cm axial field of view and a ring diameter of 16.6 cm. We measured the energy resolution, scatter fraction, sensitivity, spatial resolution, and counting rate performance of the scanner. In addition, we scanned the NEMA image-quality phantom, Micro Deluxe and Ultra-Micro Hot Spot phantoms, and 2 healthy mice. The system average energy resolution was 14% at 511 keV. The average spatial resolution at the center of the field of view was about 1.2 mm, improving to 0.8 mm and remaining below 1.2 mm in the central 6-cm field of view when a resolution-recovery method was used. The absolute sensitivity of the camera was 6.38% for an energy window of 350-650 keV and a coincidence timing window of 3.4 ns. The system scatter fraction was 11.9% for the NEMA mouselike phantom and 28% for the ratlike phantom. The maximum noise-equivalent counting rate was 1,100 at 57 MBq for the mouselike phantom and 352 kcps at 65 MBq for the ratlike phantom. The 1-mm fillable rod was clearly observable using the NEMA image-quality phantom. The images of the Ultra-Micro Hot Spot phantom also showed the 1-mm hot rods. In the mouse studies, both the left and right ventricle walls were clearly observable, as were the Harderian glands. The MuPET camera has excellent resolution, sensitivity, counting rate, and imaging performance. The data show it is a powerful scanner for preclinical animal study and pharmaceutical development.

Absolute detection efficiency of a microchannel plate detector to X rays in the 1-100 KeV energy range

NASA Astrophysics Data System (ADS)

Burginyon, Gary A.; Jacoby, Barry A.; Wobser, James K.; Ernst, Richard; Ancheta, Dione S.; Tirsell, Kenneth G.

1993-02-01

There is little information in the literature on the performance of working micro-channel plate (MCP) detectors at high x-ray energies. We have measured the absolute efficiency of a microchannel-plate-intensified, subnanosecond, one dimensional imaging x-ray detector developed at LLNL in the 1 to 100 keV range and at 1.25 MeV. The detector consists of a gold photocathode deposited on the front surface of the MCP (optimized for Ni K(subscript (alpha) ) x rays) to convert x rays to electrons, an MCP to amplify the electrons, and a fast In:CdS phosphor that converts the electron's kinetic energy to light. The phosphor is coated on a fiber-optic faceplate to transmit the light out of the vacuum system. Electrostatic focusing electrodes compress the electron current out of the MCP in one dimension while preserving spatial resolution in the other. The calibration geometry, dictated by a recent experiment, required grazing incidence x rays (15.6 degree(s)) onto the MCP detector in order to maximize deliverable current. The experiment also used a second detector made up of 0.071 in. thick BC422 plastic scintillator material from the Bicron Corporation. We compare the absolute efficiencies of these two detectors in units of optical W/cm(superscript 2) into 4 (pi) per x ray W/cm(superscript 2) incident. At 7.47 keV and 900 volts MCP bias, the MCP detector delivers approximately 1400 times more light than the scintillator detector.

LYRA, solar uv radiometer on the technology demonstration platform PROBA-2

NASA Astrophysics Data System (ADS)

Stockman, Y.; Hochedez, J.-F.; Schmutz, W.; BenMoussa, A.; Defise, J.-M.; Denis, F.; D'Olieslaeger, M.; Dominique, M.; Haenen, K.; Halain, J.-P.; Koller, S.; Koizumi, S.; Mortet, V.; Rochus, P.; Schühle, U.; Soltani, A.; Theissen, A.

2017-11-01

LYRA is a solar radiometer part of the PROBA 2 micro satellite payload. LYRA will monitor the solar irradiance in four soft X-Ray - VUV passbands. They have been chosen for their relevance to Solar Physics, Aeronomy and SpaceWeather: 1/ Lyman Alpha channel, 2/ Herzberg continuum range, 3/ Aluminium filter channel (including He II at 30.4 nm) and 4/ Zirconium filter channel. The radiometric calibration is traceable to synchrotron source standards. The stability will be monitored by on-board calibration sources (LEDs), which allow us to distinguish between potential degradations of the detectors and filters. Additionally, a redundancy strategy maximizes the accuracy and the stability of the measurements. LYRA will benefit from wide bandgap detectors based on diamond: it will be the first space assessment of revolutionary UV detectors. Diamond sensors make the instruments radiation-hard and solar-blind (insensitive to visible light) and therefore, make dispensable visible light blocking filters. To correlate the data of this new detector technology, well known technology, such as Si detectors are also embarked. The SWAP EUV imaging telescope will operate next to LYRA on PROBA-2. Together, they will provide a high performance solar monitor for operational space weather nowcasting and research. LYRA demonstrates technologies important for future missions such as the ESA Solar Orbiter.

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

Acciarri, R.; Adams, C.; An, R.

The MicroBooNE detector is a liquid argon time projection chamber at Fermilab designed to study short-baseline neutrino oscillations and neutrino-argon interaction cross-section. Due to its location near the surface, a good understanding of cosmic muons as a source of backgrounds is of fundamental importance for the experiment. We present a method of using an external 0.5 m (L) x 0.5 m (W) muon counter stack, installed above the main detector, to determine the cosmic-ray reconstruction efficiency in MicroBooNE. Data are acquired with this external muon counter stack placed in three different positions, corresponding to cosmic rays intersecting different parts of the detector. The data reconstruction efficiency of tracks in the detector is found to bemore » $$\\epsilon_{\\mathrm{data}}=(97.1\\pm0.1~(\\mathrm{stat}) \\pm 1.4~(\\mathrm{sys}))\\%$$, in good agreement with the Monte Carlo reconstruction efficiency $$\\epsilon_{\\mathrm{MC}} = (97.4\\pm0.1)\\%$$. This analysis represents a small-scale demonstration of the method that can be used with future data coming from a recently installed cosmic-ray tagger system, which will be able to tag $$\\approx80\\%$$ of the cosmic rays passing through the MicroBooNE detector.« less

MPGD for breast cancer prevention: a high resolution and low dose radiation medical imaging

NASA Astrophysics Data System (ADS)

Gutierrez, R. M.; Cerquera, E. A.; Mañana, G.

2012-07-01

Early detection of small calcifications in mammograms is considered the best preventive tool of breast cancer. However, existing digital mammography with relatively low radiation skin exposure has limited accessibility and insufficient spatial resolution for small calcification detection. Micro Pattern Gaseous Detectors (MPGD) and associated technologies, increasingly provide new information useful to generate images of microscopic structures and make more accessible cutting edge technology for medical imaging and many other applications. In this work we foresee and develop an application for the new information provided by a MPGD camera in the form of highly controlled images with high dynamical resolution. We present a new Super Detail Image (S-DI) that efficiently profits of this new information provided by the MPGD camera to obtain very high spatial resolution images. Therefore, the method presented in this work shows that the MPGD camera with SD-I, can produce mammograms with the necessary spatial resolution to detect microcalcifications. It would substantially increase efficiency and accessibility of screening mammography to highly improve breast cancer prevention.

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

Gao, Lan, E-mail: lgao@pppl.gov; Hill, K. W.; Bitter, M.

A high spatial resolution of a few μm is often required for probing small-scale high-energy-density plasmas using high resolution x-ray imaging spectroscopy. This resolution can be achieved by adjusting system magnification to overcome the inherent limitation of the detector pixel size. Laboratory experiments on investigating the relation between spatial resolution and system magnification for a spherical crystal spectrometer are presented. Tungsten Lβ{sub 2} rays from a tungsten-target micro-focus x-ray tube were diffracted by a Ge 440 crystal, which was spherically bent to a radius of 223 mm, and imaged onto an x-ray CCD with 13-μm pixel size. The source-to-crystal (p)more » and crystal-to-detector (q) distances were varied to produce spatial magnifications (M = q/p) ranging from 2 to 10. The inferred instrumental spatial width reduces with increasing system magnification M. However, the experimental measurement at each M is larger than the theoretical value of pixel size divided by M. Future work will focus on investigating possible broadening mechanisms that limit the spatial resolution.« less

Spatial resolution of a spherical x-ray crystal spectrometer at various magnifications

DOE PAGES

Gao, Lan; Hill, K. W.; Bitter, M.; ...

2016-08-23

Here, a high spatial resolution of a few μm is often required for probing small-scale high-energy-density plasmas using high resolution x-ray imaging spectroscopy. This resolution can be achieved by adjusting system magnification to overcome the inherent limitation of the detector pixel size. Laboratory experiments on investigating the relation between spatial resolution and system magnification for a spherical crystal spectrometer are presented. Tungsten Lβ 2 rays from a tungsten-target micro-focus x-ray tube were diffracted by a Ge 440 crystal, which was spherically bent to a radius of 223 mm, and imaged onto an x-ray CCD with 13-μm pixel size. The source-to-crystalmore » (p) and crystal-to-detector (q) distances were varied to produce spatial magnifications ( M = q/p) ranging from 2 to 10. The inferred instrumental spatial width reduces with increasing system magnification M. However, the experimental measurement at each M is larger than the theoretical value of pixel size divided by M. Future work will focus on investigating possible broadening mechanisms that limit the spatial resolution.« less

USB 3.0 readout and time-walk correction method for Timepix3 detector

NASA Astrophysics Data System (ADS)

Turecek, D.; Jakubek, J.; Soukup, P.

2016-12-01

The hybrid particle counting pixel detectors of Medipix family are well known. In this contribution we present new USB 3.0 based interface AdvaDAQ for Timepix3 detector. The AdvaDAQ interface is designed with a maximal emphasis to the flexibility. It is successor of FitPIX interface developed in IEAP CTU in Prague. Its modular architecture supports all Medipix/Timepix chips and all their different readout modes: Medipix2, Timepix (serial and parallel), Medipix3 and Timepix3. The high bandwidth of USB 3.0 permits readout of 1700 full frames per second with Timepix or 8 channel data acquisition from Timepix3 at frequency of 320 MHz. The control and data acquisition is integrated in a multiplatform PiXet software (MS Windows, Mac OS, Linux). In the second part of the publication a new method for correction of the time-walk effect in Timepix3 is described. Moreover, a fully spectroscopic X-ray imaging with Timepix3 detector operated in the ToT mode (Time-over-Threshold) is presented. It is shown that the AdvaDAQ's readout speed is sufficient to perform spectroscopic measurement at full intensity of radiographic setups equipped with nano- or micro-focus X-ray tubes.

The photomultiplier tube calibration system of the MicroBooNE experiment

DOE PAGES

Conrad, J.; Jones, B. J. P.; Moss, Z.; ...

2015-06-03

Here, we report on the design and construction of a LED-based fiber calibration system for large liquid argon time projection detectors. This system was developed to calibrate the optical systems of the MicroBooNE experiment. As well as detailing the materials and installation procedure, we provide technical drawings and specifications so that the system may be easily replicated in future LArTPC detectors.

LabVIEW control software for scanning micro-beam X-ray fluorescence spectrometer.

PubMed

Wrobel, Pawel; Czyzycki, Mateusz; Furman, Leszek; Kolasinski, Krzysztof; Lankosz, Marek; Mrenca, Alina; Samek, Lucyna; Wegrzynek, Dariusz

2012-05-15

Confocal micro-beam X-ray fluorescence microscope was constructed. The system was assembled from commercially available components - a low power X-ray tube source, polycapillary X-ray optics and silicon drift detector - controlled by an in-house developed LabVIEW software. A video camera coupled to optical microscope was utilized to display the area excited by X-ray beam. The camera image calibration and scan area definition software were also based entirely on LabVIEW code. Presently, the main area of application of the newly constructed spectrometer is 2-dimensional mapping of element distribution in environmental, biological and geological samples with micrometer spatial resolution. The hardware and the developed software can already handle volumetric 3-D confocal scans. In this work, a front panel graphical user interface as well as communication protocols between hardware components were described. Two applications of the spectrometer, to homogeneity testing of titanium layers and to imaging of various types of grains in air particulate matter collected on membrane filters, were presented. Copyright © 2012 Elsevier B.V. All rights reserved.

Adaptive optical filter

DOEpatents

Whittemore, Stephen Richard

2013-09-10

Imaging systems include a detector and a spatial light modulator (SLM) that is coupled so as to control image intensity at the detector based on predetermined detector limits. By iteratively adjusting SLM element values, image intensity at one or all detector elements or portions of an imaging detector can be controlled to be within limits. The SLM can be secured to the detector at a spacing such that the SLM is effectively at an image focal plane. In some applications, the SLM can be adjusted to impart visible or hidden watermarks to images or to reduce image intensity at one or a selected set of detector elements so as to reduce detector blooming

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

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

Narayan, Amrendra

2015-05-01

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scatteredmore » photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (?1 GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.« less

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

NASA Astrophysics Data System (ADS)

Narayan, Amrendra

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (~1GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.

Development of High-Speed Fluorescent X-Ray Micro-Computed Tomography

NASA Astrophysics Data System (ADS)

Takeda, T.; Tsuchiya, Y.; Kuroe, T.; Zeniya, T.; Wu, J.; Lwin, Thet-Thet; Yashiro, T.; Yuasa, T.; Hyodo, K.; Matsumura, K.; Dilmanian, F. A.; Itai, Y.; Akatsuka, T.

2004-05-01

A high-speed fluorescent x-ray CT (FXCT) system using monochromatic synchrotron x rays was developed to detect very low concentration of medium-Z elements for biomedical use. The system is equipped two types of high purity germanium detectors, and fast electronics and software. Preliminary images of a 10mm diameter plastic phantom containing channels field with iodine solutions of different concentrations showed a minimum detection level of 0.002 mg I/ml at an in-plane spatial resolution of 100μm. Furthermore, the acquisition time was reduced about 1/2 comparing to previous system. The results indicate that FXCT is a highly sensitive imaging modality capable of detecting very low concentration of iodine, and that the method has potential in biomedical applications.

Commercialization of Micro-fabrication of Antenna-Coupled Transition Edge Sensor Bolometer Detectors for Studies of the Cosmic Microwave Background

NASA Astrophysics Data System (ADS)

Suzuki, Aritoki; Bebek, Chris; Garcia-Sciveres, Maurice; Holland, Stephen; Kusaka, Akito; Lee, Adrian T.; Palaio, Nicholas; Roe, Natalie; Steinmetz, Leo

2018-04-01

We report on the development of commercially fabricated multichroic antenna-coupled transition edge sensor (TES) bolometer arrays for cosmic microwave background (CMB) polarimetry experiments. CMB polarimetry experiments have deployed instruments in stages. Stage II experiments deployed with O(1000) detectors and reported successful detection of B-mode (divergence-free) polarization pattern in the CMB. Stage III experiments have recently started observing with O(10,000) detectors with wider frequency coverage. A concept for a stage IV experiment, CMB-S4, is emerging to make a definitive measurement of CMB polarization from the ground with O(400,000) detectors. The orders of magnitude increase in detector count for CMB-S4 require a new approach in detector fabrication to increase fabrication throughput and reduce the cost. We report on collaborative efforts with two commercial micro-fabrication foundries to fabricate antenna-coupled TES bolometer detectors. The detector design is based on the sinuous antenna-coupled dichroic detector from the POLARBEAR-2 experiment. The TES bolometers showed the expected I-V response, and the RF performance agrees with the simulation. We will discuss the motivation, design consideration, fabrication processes, test results, and how industrial detector fabrication could be a path to fabricate hundreds of detector wafers for future CMB polarimetry experiments.

Uncooled Micro-Cantilever Infrared Imager Optimization

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

Panagiotis, Datskos G.

2008-02-05

We report on the development, fabrication and characterization of microcantilever based uncooled focal plane array (FPA) for infrared imaging. By combining a streamlined design of microcantilever thermal transducers with a highly efficient optical readout, we minimized the fabrication complexity while achieving a competitive level of imaging performance. The microcantilever FPAs were fabricated using a straightforward fabrication process that involved only three photolithographic steps (i.e. three masks). A designed and constructed prototype of an IR imager employed a simple optical readout based on a noncoherent low-power light source. The main figures of merit of the IR imager were found to bemore » comparable to those of uncooled MEMS infrared detectors with substantially higher degree of fabrication complexity. In particular, the NETD and the response time of the implemented MEMS IR detector were measured to be as low as 0.5K and 6 ms, respectively. The potential of the implemented designs can also be concluded from the fact that the constructed prototype enabled IR imaging of close to room temperature objects without the use of any advanced data processing. The most unique and practically valuable feature of the implemented FPAs, however, is their scalability to high resolution formats, such as 2000 x 2000, without progressively growing device complexity and cost. The overall technical objective of the proposed work was to develop uncooled infrared arrays based on micromechanical sensors. Currently used miniature sensors use a number of different readout techniques to accomplish the sensing. The use of optical readout techniques sensing require the deposition of thin coatings on the surface of micromechanical thermal detectors. Oak Ridge National Laboratory (ORNL) is uniquely qualified to perform the required research and development (R&D) services that will assist our ongoing activities. Over the past decade ORNL has developed a number of unique methods and techniques that led to improved sensors using a number of different approaches.« less

Study of a Large Prototype TPC for the ILC using Micro-Pattern Gas Detectors

NASA Astrophysics Data System (ADS)

Münnich, A.; LCTPC Collaboration

2016-04-01

In the last decade, R&D for detectors for the future International Linear Collider (ILC) has been performed by the community. The International Large Detector (ILD) is one of two detector concepts at the ILC. Its tracking system consists of a Si vertex detector, forward tracking disks and a large volume Time Projection Chamber (TPC). Within the LCTPC collaboration, a Large Prototype (LP) TPC has been built as a demonstrator. Its endplate is able to house up to seven identical modules with Micro-Pattern Gas Detectors (MPGD) amplification. Recently, the LP has been equipped with resistive anode Micromegas (MM) or Gas Electron Multiplier (GEM) modules. Both the MM and GEM technologies have been studied with an electron beam up to 6 GeV in a 1 Tesla solenoid magnet. After introducing the current R&D status, recent results will be presented including field distortions, ion gating and spatial resolution as well as future plans of the LCTPC R&D.

Noise reduction in spectral CT: reducing dose and breaking the trade-off between image noise and energy bin selection.

PubMed

Leng, Shuai; Yu, Lifeng; Wang, Jia; Fletcher, Joel G; Mistretta, Charles A; McCollough, Cynthia H

2011-09-01

Our purpose was to reduce image noise in spectral CT by exploiting data redundancies in the energy domain to allow flexible selection of the number, width, and location of the energy bins. Using a variety of spectral CT imaging methods, conventional filtered backprojection (FBP) reconstructions were performed and resulting images were compared to those processed using a Local HighlY constrained backPRojection Reconstruction (HYPR-LR) algorithm. The mean and standard deviation of CT numbers were measured within regions of interest (ROIs), and results were compared between FBP and HYPR-LR. For these comparisons, the following spectral CT imaging methods were used:(i) numerical simulations based on a photon-counting, detector-based CT system, (ii) a photon-counting, detector-based micro CT system using rubidium and potassium chloride solutions, (iii) a commercial CT system equipped with integrating detectors utilizing tube potentials of 80, 100, 120, and 140 kV, and (iv) a clinical dual-energy CT examination. The effects of tube energy and energy bin width were evaluated appropriate to each CT system. The mean CT number in each ROI was unchanged between FBP and HYPR-LR images for each of the spectral CT imaging scenarios, irrespective of bin width or tube potential. However, image noise, as represented by the standard deviation of CT numbers in each ROI, was reduced by 36%-76%. In all scenarios, image noise after HYPR-LR algorithm was similar to that of composite images, which used all available photons. No difference in spatial resolution was observed between HYPR-LR processing and FBP. Dual energy patient data processed using HYPR-LR demonstrated reduced noise in the individual, low- and high-energy images, as well as in the material-specific basis images. Noise reduction can be accomplished for spectral CT by exploiting data redundancies in the energy domain. HYPR-LR is a robust method for reducing image noise in a variety of spectral CT imaging systems without losing spatial resolution or CT number accuracy. This method improves the flexibility to select energy bins in the manner that optimizes material identification and separation without paying the penalty of increased image noise or its corollary, increased patient dose.

Diamond detector in absorbed dose measurements in high-energy linear accelerator photon and electron beams.

PubMed

Ravichandran, Ramamoorthy; Binukumar, John Pichy; Al Amri, Iqbal; Davis, Cheriyathmanjiyil Antony

2016-03-08

Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue-equivalent properties. We investigated a commercially available 'microdiamond' detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1mm, thickness 1 x10(-3) mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17% (1 SD) (n = 11). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stop-ping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long-term stability and reproducibility. Based on micro-dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance.

Co-visualization of DNA damage and ion traversals in live mammalian cells using a fluorescent nuclear track detector

PubMed Central

Kodaira, Satoshi; Konishi, Teruaki; Kobayashi, Alisa; Maeda, Takeshi; Ahmad, Tengku Ahbrizal Farizal Tengku; Yang, Gen; Akselrod, Mark S.; Furusawa, Yoshiya; Uchihori, Yukio

2015-01-01

Abstract The geometric locations of ion traversals in mammalian cells constitute important information in the study of heavy ion-induced biological effect. Single ion traversal through a cellular nucleus produces complex and massive DNA damage at a nanometer level, leading to cell inactivation, mutations and transformation. We present a novel approach that uses a fluorescent nuclear track detector (FNTD) for the simultaneous detection of the geometrical images of ion traversals and DNA damage in single cells using confocal microscopy. HT1080 or HT1080–53BP1-GFP cells were cultured on the surface of a FNTD and exposed to 5.1-MeV/n neon ions. The positions of the ion traversals were obtained as fluorescent images of a FNTD. Localized DNA damage in cells was identified as fluorescent spots of γ-H2AX or 53BP1-GFP. These track images and images of damaged DNA were obtained in a short time using a confocal laser scanning microscope. The geometrical distribution of DNA damage indicated by fluorescent γ-H2AX spots in fixed cells or fluorescent 53BP1-GFP spots in living cells was found to correlate well with the distribution of the ion traversals. This method will be useful for evaluating the number of ion hits on individual cells, not only for micro-beam but also for random-beam experiments. PMID:25324538

Imaging model for the scintillator and its application to digital radiography image enhancement.

PubMed

Wang, Qian; Zhu, Yining; Li, Hongwei

2015-12-28

Digital Radiography (DR) images obtained by OCD-based (optical coupling detector) Micro-CT system usually suffer from low contrast. In this paper, a mathematical model is proposed to describe the image formation process in scintillator. By solving the correlative inverse problem, the quality of DR images is improved, i.e. higher contrast and spatial resolution. By analyzing the radiative transfer process of visible light in scintillator, scattering is recognized as the main factor leading to low contrast. Moreover, involved blurring effect is also concerned and described as point spread function (PSF). Based on these physical processes, the scintillator imaging model is then established. When solving the inverse problem, pre-correction to the intensity of x-rays, dark channel prior based haze removing technique, and an effective blind deblurring approach are employed. Experiments on a variety of DR images show that the proposed approach could improve the contrast of DR images dramatically as well as eliminate the blurring vision effectively. Compared with traditional contrast enhancement methods, such as CLAHE, our method could preserve the relative absorption values well.

Non-invasive characterization and quality assurance of silicon micro-strip detectors using pulsed infrared laser

NASA Astrophysics Data System (ADS)

Ghosh, P.

2016-01-01

The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of roughly 1300 double sided silicon micro-strip detectors of 3 different dimensions. For the quality assurance of prototype micro-strip detectors a non-invasive detector charaterization is developed. The test system is using a pulsed infrared laser for charge injection and characterization, called Laser Test System (LTS). The system is aimed to develop a set of characterization procedures which are non-invasive (non-destructive) in nature and could be used for quality assurances of several silicon micro-strip detectors in an efficient, reliable and reproducible way. The procedures developed (as reported here) uses the LTS to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype detector modules which are tested with the LTS so far have 1024 strips with a pitch of 58 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm, wavelength = 1060 nm). The pulse with a duration of ≈ 10 ns and power ≈ 5 mW of the laser pulse is selected such, that the absorption of the laser light in the 300 μm thick silicon sensor produces ≈ 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. The laser scans different prototype sensors and various non-invasive techniques to determine characteristics of the detector modules for the quality assurance is reported.

Bio-inspired multi-mode optic flow sensors for micro air vehicles

NASA Astrophysics Data System (ADS)

Park, Seokjun; Choi, Jaehyuk; Cho, Jihyun; Yoon, Euisik

2013-06-01

Monitoring wide-field surrounding information is essential for vision-based autonomous navigation in micro-air-vehicles (MAV). Our image-cube (iCube) module, which consists of multiple sensors that are facing different angles in 3-D space, can be applied to the wide-field of view optic flows estimation (μ-Compound eyes) and to attitude control (μ- Ocelli) in the Micro Autonomous Systems and Technology (MAST) platforms. In this paper, we report an analog/digital (A/D) mixed-mode optic-flow sensor, which generates both optic flows and normal images in different modes for μ- Compound eyes and μ-Ocelli applications. The sensor employs a time-stamp based optic flow algorithm which is modified from the conventional EMD (Elementary Motion Detector) algorithm to give an optimum partitioning of hardware blocks in analog and digital domains as well as adequate allocation of pixel-level, column-parallel, and chip-level signal processing. Temporal filtering, which may require huge hardware resources if implemented in digital domain, is remained in a pixel-level analog processing unit. The rest of the blocks, including feature detection and timestamp latching, are implemented using digital circuits in a column-parallel processing unit. Finally, time-stamp information is decoded into velocity from look-up tables, multiplications, and simple subtraction circuits in a chip-level processing unit, thus significantly reducing core digital processing power consumption. In the normal image mode, the sensor generates 8-b digital images using single slope ADCs in the column unit. In the optic flow mode, the sensor estimates 8-b 1-D optic flows from the integrated mixed-mode algorithm core and 2-D optic flows with an external timestamp processing, respectively.

Identification and Quantification of Microplastics in Wastewater Using Focal Plane Array-Based Reflectance Micro-FT-IR Imaging.

PubMed

Tagg, Alexander S; Sapp, Melanie; Harrison, Jesse P; Ojeda, Jesús J

2015-06-16

Microplastics (<5 mm) have been documented in environmental samples on a global scale. While these pollutants may enter aquatic environments via wastewater treatment facilities, the abundance of microplastics in these matrices has not been investigated. Although efficient methods for the analysis of microplastics in sediment samples and marine organisms have been published, no methods have been developed for detecting these pollutants within organic-rich wastewater samples. In addition, there is no standardized method for analyzing microplastics isolated from environmental samples. In many cases, part of the identification protocol relies on visual selection before analysis, which is open to bias. In order to address this, a new method for the analysis of microplastics in wastewater was developed. A pretreatment step using 30% hydrogen peroxide (H2O2) was employed to remove biogenic material, and focal plane array (FPA)-based reflectance micro-Fourier-transform (FT-IR) imaging was shown to successfully image and identify different microplastic types (polyethylene, polypropylene, nylon-6, polyvinyl chloride, polystyrene). Microplastic-spiked wastewater samples were used to validate the methodology, resulting in a robust protocol which was nonselective and reproducible (the overall success identification rate was 98.33%). The use of FPA-based micro-FT-IR spectroscopy also provides a considerable reduction in analysis time compared with previous methods, since samples that could take several days to be mapped using a single-element detector can now be imaged in less than 9 h (circular filter with a diameter of 47 mm). This method for identifying and quantifying microplastics in wastewater is likely to provide an essential tool for further research into the pathways by which microplastics enter the environment.

Angular resolution of the gaseous micro-pixel detector Gossip

NASA Astrophysics Data System (ADS)

Bilevych, Y.; Blanco Carballo, V.; van Dijk, M.; Fransen, M.; van der Graaf, H.; Hartjes, F.; Hessey, N.; Koppert, W.; Nauta, S.; Rogers, M.; Romaniouk, A.; Veenhof, R.

2011-06-01

Gossip is a gaseous micro-pixel detector with a very thin drift gap intended for a high rate environment like at the pixel layers of ATLAS at the sLHC. The detector outputs not only the crossing point of a traversing MIP, but also the angle of the track, thus greatly simplifying track reconstruction. In this paper we describe a testbeam experiment to examine the angular resolution of the reconstructed track segments in Gossip. We used here the low diffusion gas mixture DME/CO 2 50/50. An angular resolution of 20 mrad for perpendicular tracks could be obtained from a 1.5 mm thin drift volume. However, for the prototype detector used at the testbeam experiment, the resolution of slanting tracks was worsened by poor time resolution of the pixel chip used.

Evolution of miniature detectors and focal plane arrays for infrared sensors

NASA Astrophysics Data System (ADS)

Watts, Louis A.

1993-06-01

Sensors that are sensitive in the infrared spectral region have been under continuous development since the WW2 era. A quest for the military advantage of 'seeing in the dark' has pushed thermal imaging technology toward high spatial and temporal resolution for night vision equipment, fire control, search track, and seeker 'homing' guidance sensing devices. Similarly, scientific applications have pushed spectral resolution for chemical analysis, remote sensing of earth resources, and astronomical exploration applications. As a result of these developments, focal plane arrays (FPA) are now available with sufficient sensitivity for both high spatial and narrow bandwidth spectral resolution imaging over large fields of view. Such devices combined with emerging opto-electronic developments in integrated FPA data processing techniques can yield miniature sensors capable of imaging reflected sunlight in the near IR and emitted thermal energy in the Mid-wave (MWIR) and longwave (LWIR) IR spectral regions. Robotic space sensors equipped with advanced versions of these FPA's will provide high resolution 'pictures' of their surroundings, perform remote analysis of solid, liquid, and gas matter, or selectively look for 'signatures' of specific objects. Evolutionary trends and projections of future low power micro detector FPA developments for day/night operation or use in adverse viewing conditions are presented in the following test.

Evolution of miniature detectors and focal plane arrays for infrared sensors

NASA Technical Reports Server (NTRS)

Watts, Louis A.

1993-01-01

Sensors that are sensitive in the infrared spectral region have been under continuous development since the WW2 era. A quest for the military advantage of 'seeing in the dark' has pushed thermal imaging technology toward high spatial and temporal resolution for night vision equipment, fire control, search track, and seeker 'homing' guidance sensing devices. Similarly, scientific applications have pushed spectral resolution for chemical analysis, remote sensing of earth resources, and astronomical exploration applications. As a result of these developments, focal plane arrays (FPA) are now available with sufficient sensitivity for both high spatial and narrow bandwidth spectral resolution imaging over large fields of view. Such devices combined with emerging opto-electronic developments in integrated FPA data processing techniques can yield miniature sensors capable of imaging reflected sunlight in the near IR and emitted thermal energy in the Mid-wave (MWIR) and longwave (LWIR) IR spectral regions. Robotic space sensors equipped with advanced versions of these FPA's will provide high resolution 'pictures' of their surroundings, perform remote analysis of solid, liquid, and gas matter, or selectively look for 'signatures' of specific objects. Evolutionary trends and projections of future low power micro detector FPA developments for day/night operation or use in adverse viewing conditions are presented in the following test.

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

PubMed

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

2003-06-21

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

Cherenkov light imaging tests with state-of-the-art solid state photon counter for the CLAS12 RICH detector

NASA Astrophysics Data System (ADS)

Balossino, Ilaria; Barion, L.; Contalbrigo, M.; Lenisa, P.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Movsisyan, A.; Squerzanti, S.; Turisini, M.

2017-12-01

A large area ring-imaging Cherenkov detector will be operated for hadron identification in the 3 GeV / c to 8 GeV / c momentum range at the CLAS12 experiment at the upgraded continuous electron beam accelerator facility of Jefferson Lab. The detector, consisting of aerogel radiator, composite mirrors and photon counters, will be built with a hybrid optics design to allow the detection of Cherenkov light for both forward and large angle hadron tracks. The active area has to be densely packed and highly segmented, covering about 1m2 with pixels of 6mm2 , and to allow a time resolution of 1 ns. A technology that can offer a cost-effective solution and low material budget could be Silicon Photomultipliers (SiPM) thanks to their high gain at low bias voltage, fast timing, good single-photoelectron resolution and insensitivity to magnetic fields. An investigation is ongoing on samples of 3 × 3mm2 SiPM of different micro-cell size to assess the single photon detection capability in the presence of high dark count rate due to thermal generation effects, after-pulses or optical cross-talk and to study the response to the moderate radiation damage expected at CLAS12. In this work, a brief review of the latest and most interesting results from these studies will be shown.

Analysis of axial spatial resolution in a variable resolution x-ray cone beam CT (VRX-CBCT) system

NASA Astrophysics Data System (ADS)

Dahi, Bahram; Keyes, Gary S.; Rendon, David A.; DiBianca, Frank A.

2008-03-01

The Variable Resolution X-ray (VRX) technique has been successfully used in a Cone-Beam CT (CBCT) system to increase the spatial resolution of CT images in the transverse plane. This was achieved by tilting the Flat Panel Detector (FPD) to smaller vrx y angles in a VRX Cone Beam CT (VRX-CBCT) system. In this paper, the effect on the axial spatial resolution of CT images created by the VRX-CBCT system is examined at different vrx x angles, where vrx x is the tilting angle of the FPD about its x-axis. An amorphous silicon FPD with a CsI scintillator is coupled with a micro-focus x-ray tube to form a CBCT. The FPD is installed on a rotating frame that allows rotation of up to 90° about x and y axes of the FPD. There is no rotation about the z-axis (i.e. normal to the imaging surface). Tilting the FPD about its x-axis (i.e. decreasing the vrx x angle) reduces both the width of the line-spread function and the sampling distance by a factor of sin vrx x, thereby increasing the theoretical detector pre-sampling spatial resolution proportionately. This results in thinner CT slices that in turn help increase the axial spatial resolution of the CT images. An in-house phantom is used to measure the MTF of the reconstructed CT images at different vrx x angles.

Formation Control of the MAXIM L2 Libration Orbit Mission

NASA Technical Reports Server (NTRS)

Folta, David; Hartman, Kate; Howell, Kathleen; Marchand, Belinda

2004-01-01

The Micro-Arcsecond X-ray Imaging Mission (MAXIM), a proposed concept for the Structure and Evolution of the Universe (SEU) Black Hole Imager mission, is designed to make a ten million-fold improvement in X-ray image clarity of celestial objects by providing better than 0.1 micro-arcsecond imaging. Currently the mission architecture comprises 25 spacecraft, 24 as optics modules and one as the detector, which will form sparse sub-apertures of a grazing incidence X-ray interferometer covering the 0.3-10 keV bandpass. This formation must allow for long duration continuous science observations and also for reconfiguration that permits re-pointing of the formation. To achieve these mission goals, the formation is required to cooperatively point at desired targets. Once pointed, the individual elements of the MAXIM formation must remain stable, maintaining their relative positions and attitudes below a critical threshold. These pointing and formation stability requirements impact the control and design of the formation. In this paper, we provide analysis of control efforts that are dependent upon the stability and the configuration and dimensions of the MAXIM formation. We emphasize the utilization of natural motions in the Lagrangian regions to minimize the control efforts and we address continuous control via input feedback linearization (IFL). Results provide control cost, configuration options, and capabilities as guidelines for the development of this complex mission.

Evaluation of accelerated iterative x-ray CT image reconstruction using floating point graphics hardware.

PubMed

Kole, J S; Beekman, F J

2006-02-21

Statistical reconstruction methods offer possibilities to improve image quality as compared with analytical methods, but current reconstruction times prohibit routine application in clinical and micro-CT. In particular, for cone-beam x-ray CT, the use of graphics hardware has been proposed to accelerate the forward and back-projection operations, in order to reduce reconstruction times. In the past, wide application of this texture hardware mapping approach was hampered owing to limited intrinsic accuracy. Recently, however, floating point precision has become available in the latest generation commodity graphics cards. In this paper, we utilize this feature to construct a graphics hardware accelerated version of the ordered subset convex reconstruction algorithm. The aims of this paper are (i) to study the impact of using graphics hardware acceleration for statistical reconstruction on the reconstructed image accuracy and (ii) to measure the speed increase one can obtain by using graphics hardware acceleration. We compare the unaccelerated algorithm with the graphics hardware accelerated version, and for the latter we consider two different interpolation techniques. A simulation study of a micro-CT scanner with a mathematical phantom shows that at almost preserved reconstructed image accuracy, speed-ups of a factor 40 to 222 can be achieved, compared with the unaccelerated algorithm, and depending on the phantom and detector sizes. Reconstruction from physical phantom data reconfirms the usability of the accelerated algorithm for practical cases.

Characterization of a detector chain using a FPGA-based time-to-digital converter to reconstruct the three-dimensional coordinates of single particles at high flux

NASA Astrophysics Data System (ADS)

Nogrette, F.; Heurteau, D.; Chang, R.; Bouton, Q.; Westbrook, C. I.; Sellem, R.; Clément, D.

2015-11-01

We report on the development of a novel FPGA-based time-to-digital converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of micro-channel plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1 × 106 s-1 and three-dimensional reconstruction of the coordinates up to 3.2 × 106 particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of the detector to be 140(20) μm at a flux of 3 × 105 particles per second. In addition, we analyze a method to estimate the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work apply to the detection of other kinds of particles.

Four-dimensional positron age-momentum correlation

NASA Astrophysics Data System (ADS)

Ackermann, Ulrich; Löwe, Benjamin; Dickmann, Marcel; Mitteneder, Johannes; Sperr, Peter; Egger, Werner; Reiner, Markus; Dollinger, Günther

2016-11-01

We have performed first four-dimensional age-momentum correlation (4D-AMOC) measurements at a pulsed high intensity positron micro beam and determined the absolute value of the three-dimensional momentum of the electrons annihilating with the positrons in coincidence with the positron age in the sample material. We operated two position sensitive detectors in coincidence to measure the annihilation radiation: a pixelated HPGe-detector and a microchannel plate image intensifier with a CeBr3 scintillator pixel array. The transversal momentum resolution of the 4D-AMOC setup was measured to be about 17 × 10-3 {m}0c (FWHM) and was circa 3.5 times larger than the longitudinal momentum resolution. The total time resolution was 540 ps (FWHM). We measured two samples: a gold foil and a carbon tape at a positron implantation energy of 2 keV. For each sample discrete electron momentum states and their respective positron lifetimes were extracted.

Time and position sensitive single photon detector for scintillator read-out

NASA Astrophysics Data System (ADS)

Schössler, S.; Bromberger, B.; Brandis, M.; Schmidt, L. Ph H.; Tittelmeier, K.; Czasch, A.; Dangendorf, V.; Jagutzki, O.

2012-02-01

We have developed a photon counting detector system for combined neutron and γ radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy γ radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate γ energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).

Performance evaluation of a high-resolution brain PET scanner using four-layer MPPC DOI detectors.

PubMed

Watanabe, Mitsuo; Saito, Akinori; Isobe, Takashi; Ote, Kibo; Yamada, Ryoko; Moriya, Takahiro; Omura, Tomohide

2017-08-18

A high-resolution positron emission tomography (PET) scanner, dedicated to brain studies, was developed and its performance was evaluated. A four-layer depth of interaction detector was designed containing five detector units axially lined up per layer board. Each of the detector units consists of a finely segmented (1.2 mm) LYSO scintillator array and an 8  ×  8 array of multi-pixel photon counters. Each detector layer has independent front-end and signal processing circuits, and the four detector layers are assembled as a detector module. The new scanner was designed to form a detector ring of 430 mm diameter with 32 detector modules and 168 detector rings with a 1.2 mm pitch. The total crystal number is 655 360. The transaxial and axial field of views (FOVs) are 330 mm in diameter and 201.6 mm, respectively, which are sufficient to measure a whole human brain. The single-event data generated at each detector module were transferred to the data acquisition servers through optical fiber cables. The single-event data from all detector modules were merged and processed to create coincidence event data in on-the-fly software in the data acquisition servers. For image reconstruction, the high-resolution mode (HR-mode) used a 1.2 mm 2 crystal segment size and the high-speed mode (HS-mode) used a 4.8 mm 2 size by collecting 16 crystal segments of 1.2 mm each to reduce the computational cost. The performance of the brain PET scanner was evaluated. For the intrinsic spatial resolution of the detector module, coincidence response functions of the detector module pair, which faced each other at various angles, were measured by scanning a 0.25 mm diameter 22 Na point source. The intrinsic resolutions were obtained with 1.08 mm full width at half-maximum (FWHM) and 1.25 mm FWHM on average at 0 and 22.5 degrees in the first layer pair, respectively. The system spatial resolutions were less than 1.0 mm FWHM throughout the whole FOV, using a list-mode dynamic RAMLA (LM-DRAMA). The system sensitivity was 21.4 cps kBq -1 as measured using an 18 F line source aligned with the center of the transaxial FOV. High count rate capability was evaluated using a cylindrical phantom (20 cm diameter  ×  70 cm length), resulting in 249 kcps in true and 27.9 kcps at 11.9 kBq ml -1 at the peak count in a noise equivalent count rate (NECR_2R). Single-event data acquisition and on-the-fly software coincidence detection performed well, exceeding 25 Mcps and 2.3 Mcps for single and coincidence count rates, respectively. Using phantom studies, we also demonstrated its imaging capabilities by means of a 3D Hoffman brain phantom and an ultra-micro hot-spot phantom. The images obtained were of acceptable quality for high-resolution determination. As clinical and pre-clinical studies, we imaged brains of a human and of small animals.

Performance evaluation of a high-resolution brain PET scanner using four-layer MPPC DOI detectors

NASA Astrophysics Data System (ADS)

Watanabe, Mitsuo; Saito, Akinori; Isobe, Takashi; Ote, Kibo; Yamada, Ryoko; Moriya, Takahiro; Omura, Tomohide

2017-09-01

A high-resolution positron emission tomography (PET) scanner, dedicated to brain studies, was developed and its performance was evaluated. A four-layer depth of interaction detector was designed containing five detector units axially lined up per layer board. Each of the detector units consists of a finely segmented (1.2 mm) LYSO scintillator array and an 8  ×  8 array of multi-pixel photon counters. Each detector layer has independent front-end and signal processing circuits, and the four detector layers are assembled as a detector module. The new scanner was designed to form a detector ring of 430 mm diameter with 32 detector modules and 168 detector rings with a 1.2 mm pitch. The total crystal number is 655 360. The transaxial and axial field of views (FOVs) are 330 mm in diameter and 201.6 mm, respectively, which are sufficient to measure a whole human brain. The single-event data generated at each detector module were transferred to the data acquisition servers through optical fiber cables. The single-event data from all detector modules were merged and processed to create coincidence event data in on-the-fly software in the data acquisition servers. For image reconstruction, the high-resolution mode (HR-mode) used a 1.2 mm2 crystal segment size and the high-speed mode (HS-mode) used a 4.8 mm2 size by collecting 16 crystal segments of 1.2 mm each to reduce the computational cost. The performance of the brain PET scanner was evaluated. For the intrinsic spatial resolution of the detector module, coincidence response functions of the detector module pair, which faced each other at various angles, were measured by scanning a 0.25 mm diameter 22Na point source. The intrinsic resolutions were obtained with 1.08 mm full width at half-maximum (FWHM) and 1.25 mm FWHM on average at 0 and 22.5 degrees in the first layer pair, respectively. The system spatial resolutions were less than 1.0 mm FWHM throughout the whole FOV, using a list-mode dynamic RAMLA (LM-DRAMA). The system sensitivity was 21.4 cps kBq-1 as measured using an 18F line source aligned with the center of the transaxial FOV. High count rate capability was evaluated using a cylindrical phantom (20 cm diameter  ×  70 cm length), resulting in 249 kcps in true and 27.9 kcps at 11.9 kBq ml-1 at the peak count in a noise equivalent count rate (NECR_2R). Single-event data acquisition and on-the-fly software coincidence detection performed well, exceeding 25 Mcps and 2.3 Mcps for single and coincidence count rates, respectively. Using phantom studies, we also demonstrated its imaging capabilities by means of a 3D Hoffman brain phantom and an ultra-micro hot-spot phantom. The images obtained were of acceptable quality for high-resolution determination. As clinical and pre-clinical studies, we imaged brains of a human and of small animals.

Design and development of a ferroelectric micro photo detector for the bionic eye

NASA Astrophysics Data System (ADS)

Song, Yang

Driven by no effective therapy for Retinitis Pigmentosa and Age Related Macular Degeneration, artificial vision through the development of an artificial retina that can be implanted into the human eye, is being addressed by the Bionic Eye. This dissertation focuses on the study of a photoferroelectric micro photo detector as an implantable retinal prosthesis for vision restoration in patients with above disorders. This implant uses an electrical signal to trigger the appropriate ocular cells of the vision system without resorting to wiring or electrode implantation. The research work includes fabrication of photoferroelectric thin film micro detectors, characterization of these photoferroelectric micro devices as photovoltaic cells, and Finite Element Method (FEM) modeling of the photoferroelectrics and their device-neuron interface. A ferroelectric micro detector exhibiting the photovoltaic effect (PVE) directly adds electrical potential to the neuron membrane outer wall at the focal adhesion regions. The electrical potential then generates a retinal cell membrane potential deflection through a newly developed Direct-Electric-Field-Coupling (DEFC) model. This model is quite different from the traditional electric current model because instead of current directly working on the cell membrane, the PVE current is used to generate a localized high electric potential in the focal adhesion region by working together with the anisotropic high internal impedance of ferroelectric thin films. General electrodes and silicon photodetectors do not have such anisotropy and high impedance, and thus they cannot generate DEFC. This mechanism investigation is very valuable, because it clearly shows that our artificial retina works in a way that is totally different from the traditional current stimulation methods.

Estudio de un microcable de par trenzado para la comunicacion y lectura del modulo de pixeles del experimento CMS

NASA Astrophysics Data System (ADS)

Oliveros Tautiva, Sandra Jimena

The Compact Muon Solenoid (CMS) is one of the two most important experiments at the Large Hadron Collider (LHC). The pixel detector is the component closest to the collision in CMS and it receives large doses of radiation which will affect its performance. The pixel detector will be replaced by a new one after four years. The aim is to reduce material in the sensitive zone of the new pixel detector, which leads to the implementation of a type of micro twisted pair cable that will replace the existing kapton cables and some connections will be eliminated. The purpose of this work was to study the viability of using these micro twisted pair cables in the existing 40 MHz analog readout. The electrical parameters of micro cables were determined, and operational tests were performed in a module using these cables for communicating and reading. Three different lengths of micro cables were used, 1.0, 1.5 and 2.0 m, in order to compare test results with those obtained using the kapton cable. It was found that the use of these cables does not affect the programming and reading of the pixels in one module, so the micro cables are viable to be used in place of the kapton cables.

Slit-scanning differential phase-contrast mammography: first experimental results

NASA Astrophysics Data System (ADS)

Roessl, Ewald; Daerr, Heiner; Koehler, Thomas; Martens, Gerhard; van Stevendaal, Udo

2014-03-01

The demands for a large field-of-view (FOV) and the stringent requirements for a stable acquisition geometry rank among the major obstacles for the translation of grating-based, differential phase-contrast techniques from the laboratory to clinical applications. While for state-of-the-art Full-Field-Digital Mammography (FFDM) FOVs of 24 cm x 30 cm are common practice, the specifications for mechanical stability are naturally derived from the detector pixel size which ranges between 50 and 100 μm. However, in grating-based, phasecontrast imaging, the relative placement of the gratings in the interferometer must be guaranteed to within micro-meter precision. In this work we report on first experimental results on a phase-contrast x-ray imaging system based on the Philips MicroDose L30 mammography unit. With the proposed approach we achieve a FOV of about 65 mm x 175 mm by the use of the slit-scanning technique. The demand for mechanical stability on a micrometer scale was relaxed by the specific interferometer design, i.e., a rigid, actuator-free mount of the phase-grating G1 with respect to the analyzer-grating G2 onto a common steel frame. The image acquisition and formation processes are described and first phase-contrast images of a test object are presented. A brief discussion of the shortcomings of the current approach is given, including the level of remaining image artifacts and the relatively inefficient usage of the total available x-ray source output.

Gaseous Electron Multiplier (GEM) Detectors

NASA Astrophysics Data System (ADS)

Gnanvo, Kondo

2017-09-01

Gaseous detectors have played a pivotal role as tracking devices in the field of particle physics experiments for the last fifty years. Recent advances in photolithography and micro processing techniques have enabled the transition from Multi Wire Proportional Chambers (MWPCs) and Drift Chambers to a new family of gaseous detectors refer to as Micro Pattern Gaseous Detectors (MPGDs). MPGDs combine the basic gas amplification principle with micro-structure printed circuits to provide detectors with excellent spatial and time resolution, high rate capability, low material budget and high radiation tolerance. Gas Electron Multiplier (GEMs) is a well-established MPGD technology invented by F. Sauli at CERN in 1997 and deployed various high energy physics (HEP) and nuclear NP experiment for tracking systems of current and future NP experiments. GEM detector combines an exceptional high rate capability (1 MHz / mm2) and robustness against harsh radiation environment with excellent position and timing resolution performances. Recent breakthroughs over the past decade have allowed the possibility for large area GEMs, making them cost effective and high-performance detector candidates to play pivotal role in current and future particle physics experiments. After a brief introduction of the basic principle of GEM technology, I will give a brief overview of the GEM detectors used in particle physics experiments over the past decades and especially in the NP community at Thomas Jefferson National Laboratory (JLab) and Brookhaven National Laboratory (BNL). I will follow by a review of state of the art of the new GEM development for the next generation of colliders such as Electron Ion Collider (EIC) or High Luminosity LHC and future Nuclear Physics experiments. I will conclude with a presentation of the CERN-based RD51 collaboration established in 2008 and its major achievements regarding technological developments and applications of MPGDs.

Efficient single-pixel multispectral imaging via non-mechanical spatio-spectral modulation.

PubMed

Li, Ziwei; Suo, Jinli; Hu, Xuemei; Deng, Chao; Fan, Jingtao; Dai, Qionghai

2017-01-27

Combining spectral imaging with compressive sensing (CS) enables efficient data acquisition by fully utilizing the intrinsic redundancies in natural images. Current compressive multispectral imagers, which are mostly based on array sensors (e.g, CCD or CMOS), suffer from limited spectral range and relatively low photon efficiency. To address these issues, this paper reports a multispectral imaging scheme with a single-pixel detector. Inspired by the spatial resolution redundancy of current spatial light modulators (SLMs) relative to the target reconstruction, we design an all-optical spectral splitting device to spatially split the light emitted from the object into several counterparts with different spectrums. Separated spectral channels are spatially modulated simultaneously with individual codes by an SLM. This no-moving-part modulation ensures a stable and fast system, and the spatial multiplexing ensures an efficient acquisition. A proof-of-concept setup is built and validated for 8-channel multispectral imaging within 420~720 nm wavelength range on both macro and micro objects, showing a potential for efficient multispectral imager in macroscopic and biomedical applications.

[New methods for the evaluation of bone quality. Assessment of bone structural property using imaging.

PubMed

Ito, Masako

Structural property of bone includes micro- or nano-structural property of the trabecular and cortical bone, and macroscopic geometry. Radiological technique is useful to analyze the bone structural property;multi-detector row CT(MDCT)or high-resolution peripheral QCT(HR-pQCT)is available to analyze human bone in vivo . For the analysis of hip geometry, CT-based hip structure analysis(HSA)is available as well as DXA-based HSA. These structural parameters are related to biomechanical property, and these assessment tools provide information of pathological changes or the effects of anti-osteoporotic agents on bone.

Thermal Design for the Micro-X Rocket Payload

NASA Astrophysics Data System (ADS)

Goldfinger, D. C.; Figueroa-Feliciano, E.; Danowski, M.; Heine, S. N. T.

2016-08-01

Micro-X is a NASA funded, rocket borne X-ray imaging spectrometer that uses transition edge sensors (TESs) to do high-resolution microcalorimetry. The TESs are cooled by an adiabatic demagnetization refrigerator, whose salt pill functions as a heat sink for the detectors. We have made a thermal model of the cryostat with SPICE for the purposes of understanding its behavior at low temperatures. Implementing modifications based on this model has further allowed us to cool the system down to a lower temperature than had previously been accessible and to improve its low-temperature hold time. These modifications include a variety of schemes for power through heat sinks and tweaking the conductance between the cold baths and the refrigerated hardware. We present an overview of the model and its constituent parameters, information about thermal modifications, and a summary of results from thermal tests of the entire system.

Towards high-resolution neutron imaging on IMAT

NASA Astrophysics Data System (ADS)

Minniti, T.; Tremsin, A. S.; Vitucci, G.; Kockelmann, W.

2018-01-01

IMAT is a new cold-neutron imaging facility at the neutron spallation source ISIS at the Rutherford Appleton Laboratory, U.K.. The ISIS pulsed source enables energy-selective and energy-resolved neutron imaging via time-of-flight (TOF) techniques, which are available in addition to the white-beam neutron radiography and tomography options. A spatial resolution of about 50 μm for white-beam neutron radiography was achieved early in the IMAT commissioning phase. In this work we have made the first steps towards achieving higher spatial resolution. A white-beam radiography with 18 μm spatial resolution was achieved in this experiment. This result was possible by using the event counting neutron pixel detector based on micro-channel plates (MCP) coupled with a Timepix readout chip with 55 μm sized pixels, and by employing an event centroiding technique. The prospects for energy-selective neutron radiography for this centroiding mode are discussed.

THE ADIABATIC DEMAGNETIZATION REFRIGERATOR FOR THE MICRO-X SOUNDING ROCKET TELESCOPE

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

Wikus, P.; Bagdasarova, Y.; Figueroa-Feliciano, E.

2010-04-09

The Micro-X Imaging X-ray Spectrometer is a sounding rocket payload slated for launch in 2011. An array of Transition Edge Sensors, which is operated at a bath temperature of 50 mK, will be used to obtain a high resolution spectrum of the Puppis-A supernova remnant. An Adiabatic Demagnetization Refrigerator (ADR) with a 75 gram Ferric Ammonium Alum (FAA) salt pill in the bore of a 4 T superconducting magnet provides a stable heat sink for the detector array only a few seconds after burnout of the rocket motors. This requires a cold stage design with very short thermal time constants.more » A suspension made from Kevlar strings holds the 255 gram cold stage in place. It is capable of withstanding loads in excess of 200 g. Stable operation of the TES array in proximity to the ADR magnet is ensured by a three-stage magnetic shielding system which consists of a superconducting can, a high-permeability shield and a bucking coil. The development and testing of the Micro-X payload is well underway.« less

Multifunctional semiconductor micro-Hall devices for magnetic, electric, and photo-detection

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

Gilbertson, A. M.; Cohen, L. F.; Sadeghi, Hatef

2015-12-07

We report the real-space voltage response of InSb/AlInSb micro-Hall devices to local photo-excitation, electric, and magnetic fields at room temperature using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local electric fields. Experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. The magnetic, photo, and charge sensitivity of a 2 μm wide probe are evaluated at a 10 μA bias current in the Johnson noise limit (valid at measurement frequencies > 10 kHz) to be, respectively, 500 nT/√Hz; 20 pW/√Hz (λ = 635 nm) comparable to commercial photoconductive detectors;more » and 0.05 e/√Hz comparable to that of single electron transistors. These results demonstrate the remarkably versatile sensing attributes of simple semiconductor micro-Hall devices that can be applied to a host of imaging and sensing applications.« less

Intercomparison of radiation measurements on STS-63.

PubMed

Badhwar, G D; Atwell, W; Cash, B; Weyland, M; Petrov, V M; Tchernykh, I V; Akatov YuA; Shurshakov, V A; Arkhangelsky, V V; Kushin, V V; Klyachin, N A; Benton, E V; Frank, A L; Benton, E R; Frigo, L A; Dudkin, V E; Potapov YuV; Vana, N; Schoner, W; Fugger, M

1996-11-01

A joint NASA Russia study of the radiation environment inside the Space Shuttle was performed on STS-63. This was the second flight under the Shuttle-Mir Science Program (Phase 1). The Shuttle was launched on 2 February 1995, in a 51.65 degrees inclination orbit and landed at Kennedy Space Center on 11 February 1995, for a total flight duration of 8.27 days. The Shuttle carried a complement of both passive and active detectors distributed throughout the Shuttle volume. The crew exposure varied from 1962 to 2790 microGy with an average of 2265.8 microGy or 273.98 microGy/day. Crew exposures varied by a factor of 1.4, which is higher than usual for STS mission. The flight altitude varied from 314 to 395 km and provided a unique opportunity to obtain dose variation with altitude. Measurements of the average east-west dose variation were made using two active solid state detectors. The dose rate in the Spacehab locker, measured using a tissue equivalent proportional counter (TEPC), was 413.3 microGy/day, consistent with measurements made using thermoluminescent detectors (TLDs) in the same locker. The average quality factor was 2.33, and although it was higher than model calculations, it was consistent with values derived from high temperature peaks in TLDs. The dose rate due to galactic cosmic radiation was 110.6 microGy/day and agreed with model calculations. The dose rate from trapped particles was 302.7 microGy/day, nearly a factor of 2 lower than the prediction of the AP8 model. The neutrons in the intermediate energy range of 1-20 MeV contributed 13 microGy/day and 156 microSv/day, respectively. Analysis of data from the charged particle spectrometer has not yet been completed.

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

PubMed

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

2018-07-01

To evaluate the impact of digital detector, dose level and post-processing on neonatal chest phantom X-ray image quality (IQ). A neonatal phantom was imaged using four different detectors: a CR powder phosphor (PIP), a CR needle phosphor (NIP) and two wireless CsI DR detectors (DXD and DRX). Five different dose levels were studied for each detector and two post-processing algorithms evaluated for each vendor. Three paediatric radiologists scored the images using European quality criteria plus additional questions on vascular lines, noise and disease simulation. Visual grading characteristics and ordinal regression statistics were used to evaluate the effect of detector type, post-processing and dose on VGA score (VGAS). No significant differences were found between the NIP, DXD and CRX detectors (p>0.05) whereas the PIP detector had significantly lower VGAS (p< 0.0001). Processing did not influence VGAS (p=0.819). Increasing dose resulted in significantly higher VGAS (p<0.0001). Visual grading analysis (VGA) identified a detector air kerma/image (DAK/image) of ~2.4 μGy as an ideal working point for NIP, DXD and DRX detectors. VGAS tracked IQ differences between detectors and dose levels but not image post-processing changes. VGA showed a DAK/image value above which perceived IQ did not improve, potentially useful for commissioning. • A VGA study detects IQ differences between detectors and dose levels. • The NIP detector matched the VGAS of the CsI DR detectors. • VGA data are useful in setting initial detector air kerma level. • Differences in NNPS were consistent with changes in VGAS.

Neutron dosimetry in low-earth orbit using passive detectors

NASA Technical Reports Server (NTRS)

Benton, E. R.; Benton, E. V.; Frank, A. L.

2001-01-01

This paper summarizes neutron dosimetry measurements made by the USF Physics Research Laboratory aboard US and Russian LEO spacecraft over the past 20 years using two types of passive detector. Thermal/resonance neutron detectors exploiting the 6Li(n,T) alpha reaction were used to measure neutrons of energies <1 MeV. Fission foil neutron detectors were used to measure neutrons of energies above 1 MeV. While originally analysed in terms of dose equivalent using the NCRP-38 definition of quality factor, for the purposes of this paper the measured neutron data have been reanalyzed and are presented in terms of ambient dose equivalent. Dose equivalent rate for neutrons <1 MeV ranged from 0.80 microSv/d on the low altitude, low inclination STS-41B mission to 22.0 microSv/d measured in the Shuttle's cargo bay on the highly inclined STS-51F Spacelab-2 mission. In one particular instance a detector embedded within a large hydrogenous mass on STS-61 (in the ECT experiment) measured 34.6 microSv/d. Dose equivalent rate measurements of neutrons >1 MeV ranged from 4.5 microSv/d on the low altitude STS-3 mission to 172 microSv/d on the 6 year LDEF mission. Thermal neutrons (<0.3 eV) were observed to make a negligible contribution to neutron dose equivalent in all cases. The major fraction of neutron dose equivalent was found to be from neutrons >1 MeV and, on LDEF, neutrons >1 MeV are responsible for over 98% of the total neutron dose equivalent. Estimates of the neutron contribution to the total dose equivalent are somewhat lower than model estimates, ranging from 5.7% at a location under low shielding on LDEF to 18.4% on the highly inclined (82.3 degrees) Biocosmos-2044 mission. c2001 Elsevier Science Ltd. All rights reserved.

Search for Bs0 --> micro+ micro- and B0 --> micro+ micro- decays with 2 fb-1 of pp collisions.

PubMed

Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'orso, M; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Giagu, S; Giakoumopolou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyria, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S

2008-03-14

We have performed a search for B(s)(0) --> micro(+) micro(-) and B(0) --> micro(+) micro(-) decays in pp collisions at square root s = 1.96 TeV using 2 fb(-1) of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron Collider. The observed number of B(s)(0) and B0 candidates is consistent with background expectations. The resulting upper limits on the branching fractions are B(B(s)0) --> micro(+) micro(-)) <5.8 x 10(-8) and B(B(0) --> micro(+) micro(-))<1.8 x 10(-8) at 95% C.L.

Multi-channel infrared thermometer

DOEpatents

Ulrickson, Michael A.

1986-01-01

A device for measuring the two-dimensional temperature profile of a surface comprises imaging optics for generating an image of the light radiating from the surface; an infrared detector array having a plurality of detectors; and a light pipe array positioned between the imaging optics and the detector array for sampling, transmitting, and distributing the image over the detector surfaces. The light pipe array includes one light pipe for each detector in the detector array.

Using a flat-panel detector in high resolution cone beam CT for dental imaging.

PubMed

Baba, R; Ueda, K; Okabe, M

2004-09-01

Cone beam CT (CBCT) requires a two-dimensional X-ray detector. In the several CBCT systems developed for dental imaging, detection has been by the combination of an X-ray image intensifier and charge-coupled device (CCD) camera. In this paper, we propose a new CBCT system in which the detector is of the flat-panel type and evaluate its performance in dental imaging. We developed a prototype CBCT that has a flat-panel-type detector. The detector consists of a CsI scintillator screen and a photosensor array. First, the flat panel detector and image intensifier detector were compared in terms of the signal-to-noise ratio (SNR) of projected images. We then used these data and a theoretical formula to evaluate noise in reconstructed images. Second, reconstructed images of a bar pattern phantom were obtained as a way of evaluating the spatial resolution. Then, reconstructed images of a skull phantom were obtained. The SNR of the developed system was 1.6 times as high as that of a system with an image intensifier detector of equal detector pitch. The system was capable of resolving a 0.35 mm pattern and its field of view almost completely encompassed that of an image intensifier detector which is used in dentomaxillofacial imaging. The fine spatial resolution of the detector led to images in which the structural details of a skull phantom were clearly visible. The system's isotropically fine resolution will lead to improved precision in dental diagnosis and surgery. The next stage of our research will be the development of a flat panel detector system with a high frame acquisition rate.

Modeling and simulation of blazed grating based on MEMS scanning micro-mirror for NIR micro-spectrometer

NASA Astrophysics Data System (ADS)

Zhou, Ying; Wen, Zhiyu; Yang, Tingyan; Lei, Hongjie

2015-11-01

Near infrared micro-spectrometer (NIRMS) as a vital detection equipment for various elements has been investigated over the last few years. Traditional MEMS NIRMS employs CCD array detectors for NIR spectrum collection and this leads to higher fabrication cost. In this paper, to ensure the higher diffraction efficiency as well as lower fabrication cost, a novel blazed grating based on MEMS scanning micro-mirror (SMM) is proposed. By our design method, the NIRMS needs only one single InGaAs detector photo diode to collect NIR spectrum and ensure the high diffraction efficiency. Our results show that the diffraction efficiency of the blazed grating is almost 50% and the peak value reaches to 90% in the range of 900-2,100 nm while the optical scanning angle is 14.2°.

Latest generation of ASICs for photodetector readout

NASA Astrophysics Data System (ADS)

Seguin-Moreau, N.

2013-08-01

The OMEGA microelectronics group has designed a new generation of multichannel integrated circuits, the "ROC" family, in AustrianMicroSystem (AMS) SiGe 0.35 μm technology to read out signals from various families of photodetectors. The chip named MAROC (standing for Multi Anode ReadOut Chip) has been designed to read out MultiAnode Photomultipliers (MAPMT), Photomultiplier ARray In SiGe ReadOut Chip (PARISROC) to read out Photomultipliers (PMTs) and SiPM Integrated ReadOut Chip (SPIROC) to readout Silicon PhotoMultiplier (SiPM) detectors and which was the first ASIC to do so. The three of them fulfill the stringent requirements of the future photodetectors, in particular in terms of low noise, radiation hardness, large dynamic range, high density and high speed while keeping low power thanks to the SiGe technology. These multi-channel ASICs are real System on Chip (SoC) as they provide charge, time and photon-counting information which are digitized internally. Their complexity and versatility enable innovative frontier detectors and also cover spin off of these detectors in adjacent fields such as medical or material imaging as well as smart detectors. In this presentation, the three ASIC architectures and test results will be described to give a general panorama of the "ROC" chips.

The readout chain for the bar PANDA MVD strip detector

NASA Astrophysics Data System (ADS)

Schnell, R.; Brinkmann, K.-Th.; Di Pietro, V.; Kleines, H.; Goerres, A.; Riccardi, A.; Rivetti, A.; Rolo, M. D.; Sohlbach, H.; Zaunick, H.-G.

2015-02-01

The bar PANDA (antiProton ANnihilation at DArmstadt) experiment will study the strong interaction in annihilation reactions between an antiproton beam and a stationary gas jet target. The detector will comprise different sub-detectors for tracking, particle identification and calorimetry. The Micro-Vertex Detector (MVD) as the innermost part of the tracking system will allow precise tracking and detection of secondary vertices. For the readout of the double-sided silicon strip sensors a custom-made ASIC is being developed, employing the Time-over-Threshold (ToT) technique for digitization and utilize time-to-digital converters (TDC) to provide a high-precision time stamp of the hit. A custom-made Module Data Concentrator ASIC (MDC) will multiplex the data of all front-ends of one sensor towards the CERN-developed GBT chip set (GigaBit Transceiver). The MicroTCA-based MVD Multiplexer Board (MMB) at the off-detector site will receive and concentrate the data from the GBT links and transfer it to FPGA-based compute nodes for global event building.

Multi-channel infrared thermometer

DOEpatents

Ulrickson, M.A.

A device for measuring the two-dimensional temperature profile of a surface comprises imaging optics for generating an image of the light radiating from the surface; an infrared detector array having a plurality of detectors; and optical means positioned between the imaging optics and the detector array for sampling, transmitting, and distributing the image over the detector surfaces. The optical means may be a light pipe array having one light pipe for each detector in the detector array.

Elemental mapping and microimaging by x-ray capillary optics.

PubMed

Hampai, D; Dabagov, S B; Cappuccio, G; Longoni, A; Frizzi, T; Cibin, G; Guglielmotti, V; Sala, M

2008-12-01

Recently, many experiments have highlighted the advantage of using polycapillary optics for x-ray fluorescence studies. We have developed a special confocal scheme for micro x-ray fluorescence measurements that enables us to obtain not only elemental mapping of the sample but also simultaneously its own x-ray imaging. We have designed the prototype of a compact x-ray spectrometer characterized by a spatial resolution of less than 100 microm for fluorescence and less than 10 microm for imaging. A couple of polycapillary lenses in a confocal configuration together with a silicon drift detector allow elemental studies of extended samples (approximately 3 mm) to be performed, while a CCD camera makes it possible to record an image of the same samples with 6 microm spatial resolution, which is limited only by the pixel size of the camera. By inserting a compound refractive lens between the sample and the CCD camera, we hope to develop an x-ray microscope for more enlarged images of the samples under test.

A high resolution prototype small-animal PET scanner dedicated to mouse brain imaging

PubMed Central

Yang, Yongfeng; Bec, Julien; Zhou, Jian; Zhang, Mengxi; Judenhofer, Martin S; Bai, Xiaowei; Di, Kun; Wu, Yibao; Rodriguez, Mercedes; Dokhale, Purushottam; Shah, Kanai S.; Farrell, Richard; Qi, Jinyi; Cherry, Simon R.

2017-01-01

A prototype small-animal PET scanner was developed based on depth-encoding detectors using dual-ended readout of very small scintillator elements to produce high and uniform spatial resolution suitable for imaging the mouse brain. Methods The scanner consists of 16 tapered dual-ended readout detectors arranged in a ring of diameter 61 mm. The axial field of view is 7 mm and the transaxial field of view is 30 mm. The scintillator arrays consist of 14×14 lutetium oxyorthosilicate (LSO) elements, with a crystal size of 0.43×0.43 mm2 at the front end and 0.80×0.43 mm2 at the back end, and the crystal elements are 13 mm long. The arrays are read out by 8×8 mm2 and a 13×8 mm2 position-sensitive avalanche photodiodes (PSAPDs) placed at opposite ends of the array. Standard nuclear instrumentation module (NIM) electronics and a custom designed multiplexer are used for signal processing. Results The detector performance was measured and all except the very edge crystals could be clearly resolved. The average detector intrinsic spatial resolution in the axial direction was 0.61 mm. A depth of interaction resolution of 1.7 mm was achieved. The sensitivity of the scanner at center of the field of view was 1.02% for a lower energy threshold of 150 keV and 0.68% for a lower energy threshold of 250 keV. The spatial resolution within a field of view that can accommodate the entire mouse brain was ~0.6 mm using a 3D Maximum Likelihood-Expectation Maximization (ML-EM) reconstruction algorithm. Images of a micro hot-rod phantom showed that rods with diameter down to 0.5 mm could be resolved. First in vivo studies were obtained using 18F-fluoride and confirmed that 0.6 mm resolution can be achieved in the mouse head in vivo. Brain imaging studies with 18F-fluorodeoxyglucose were also acquired. Conclusion A prototype PET scanner achieving a spatial resolution approaching the physical limits for a small-bore PET scanner set by positron range and acolinearity was developed. Future plans are to add more detector rings to extend the axial field of view of the scanner and increase sensitivity. PMID:27013696

Performance evaluation of G8, a high sensitivity benchtop preclinical PET/CT tomograph.

PubMed

Gu, Zheng; Taschereau, Richard; Vu, Nam; Prout, David L; Silverman, Robert W; Lee, Jason; Chatziioannou, Arion F

2018-06-14

G8 is a bench top integrated PET/CT scanner dedicated to high sensitivity and high resolution imaging of mice. This work characterizes its National Electrical Manufacturers Association (NEMA) NU4-2008 performance where applicable and also provides an assessment of the basic imaging performance of the CT subsystem. Methods: The PET subsystem in G8 consists of four flat-panel type detectors arranged in a box like geometry. Each panel consists of two modules of a 26 × 26 pixelated bismuth germanate (BGO) scintillator array with individual crystals measuring 1.75 × 1.75 × 7.2 mm. The crystal arrays are coupled to multichannel photomultiplier tubes via a tapered, pixelated glass lightguide. A cone-beam CT consisting of a micro focus X-ray source and a Complementary Metal Oxide Semiconductor (CMOS) detector provides anatomical information. Sensitivity, spatial resolution, energy resolution, scatter fraction, count-rate performance and the capability of phantom and mouse imaging were evaluated for the PET subsystem. Noise, dose level, contrast and resolution were evaluated for the CT subsystem. Results: With an energy window of 350-650 keV, the peak sensitivity was measured to be 9.0% near the center of the field of view (CFOV). The crystal energy resolution ranged from 15.0% to 69.6% full width at half maximum (FWHM), with a mean of 19.3 ± 3.7%. The average detector intrinsic spatial resolution was 1.30 mm and 1.38 mm FWHM in the transverse and axial directions. The maximum likelihood expectation maximization (ML-EM) reconstructed image of a point source in air, averaged 0.81 ± 0.11 mm FWHM. The peak noise equivalent count rate (NECR) for the mouse-sized phantom was 44 kcps for a total activity of 2.9 MBq (78 µCi) and the scatter fraction was 11%. For the CT subsystem, the value of the modulation transfer function (MTF) at 10% was 2.05 cycles/mm. Conclusion: The overall performance demonstrates that the G8 can produce high quality images for molecular imaging based biomedical research. Copyright © 2018 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Fabrication and Calibration of FORTIS

NASA Technical Reports Server (NTRS)

Fleming, Brian T.; McCandliss, Stephan R.; Kaiser, Mary Elizabeth; Kruk, Jeffery; Feldman, Paul D.; Kutyrev, Alexander S.; Li, Mary J.; Rapchun, David A.; Lyness, Eric; Moseley, S. H.;

Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

NASA Astrophysics Data System (ADS)

Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc

2016-03-01

We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.

Image reconstruction in cone-beam CT with a spherical detector using the BPF algorithm

NASA Astrophysics Data System (ADS)

Zuo, Nianming; Zou, Yu; Jiang, Tianzi; Pan, Xiaochuan

2006-03-01

Both flat-panel detectors and cylindrical detectors have been used in CT systems for data acquisition. The cylindrical detector generally offers a sampling of a transverse image plane more uniformly than does a flat-panel detector. However, in the longitudinal dimension, the cylindrical and flat-panel detectors offer similar sampling of the image space. In this work, we investigate a detector of spherical shape, which can yield uniform sampling of the 3D image space because the solid angle subtended by each individual detector bin remains unchanged. We have extended the backprojection-filtration (BPF) algorithm, which we have developed previously for cone-beam CT, to reconstruct images in cone-beam CT with a spherical detector. We also conduct computer-simulation studies to validate the extended BPF algorithm. Quantitative results in these numerical studies indicate that accurate images can be obtained from data acquired with a spherical detector by use of our extended BPF cone-beam algorithms.

Dosimetry in small-animal CT using Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Lee, C.-L.; Park, S.-J.; Jeon, P.-H.; Jo, B.-D.; Kim, H.-J.

2016-01-01

Small-animal computed tomography (micro-CT) imaging devices are increasingly being used in biological research. While investigators are mainly interested in high-contrast, low-noise, and high-resolution anatomical images, relatively large radiation doses are required, and there is also growing concern over the radiological risk from preclinical experiments. This study was conducted to determine the radiation dose in a mouse model for dosimetric estimates using the GEANT4 application for tomographic emission simulations (GATE) and to extend its techniques to various small-animal CT applications. Radiation dose simulations were performed with the same parameters as those for the measured micro-CT data, using the MOBY phantom, a pencil ion chamber and an electrometer with a CT detector. For physical validation of radiation dose, absorbed dose of brain and liver in mouse were evaluated to compare simulated results with physically measured data using thermoluminescent dosimeters (TLDs). The mean difference between simulated and measured data was less than 2.9% at 50 kVp X-ray source. The absorbed doses of 37 brain tissues and major organs of the mouse were evaluated according to kVp changes. The absorbed dose over all of the measurements in the brain (37 types of tissues) consistently increased and ranged from 42.4 to 104.0 mGy. Among the brain tissues, the absorbed dose of the hypothalamus (157.8-414.30 mGy) was the highest for the beams at 50-80 kVp, and that of the corpus callosum (11.2-26.6 mGy) was the lowest. These results can be used as a dosimetric database to control mouse doses and preclinical targeted radiotherapy experiments. In addition, to accurately calculate the mouse-absorbed dose, the X-ray spectrum, detector alignment, and uncertainty in the elemental composition of the simulated materials must be accurately modeled.

Spatial response of synthetic microDiamond and diode detectors measured with kilovoltage synchrotron radiation.

PubMed

Butler, Duncan J; Beveridge, Toby; Lehmann, Joerg; Oliver, Christopher P; Stevenson, Andrew W; Livingstone, Jayde

2018-02-01

To map the spatial response of four solid-state radiation detectors of types commonly used for radiotherapy dosimetry. PTW model 60016 Diode P, 60017 Diode E, 60018 Diode SRS, and 60019 microDiamond detectors were radiographed using a high resolution conventional X-ray system. Their spatial response was then investigated using a 0.1 mm diameter beam of 95 keV average energy photons generated by a synchrotron. The detectors were scanned through the beam while their signal was recorded as a function of position, to map the response. These 2D response maps were created in both the end-on and side-on orientations. The results show the location and size of the active region. End-on, the active area was determined to be centrally located and within 0.2 mm of the manufacturer's specified diameter. The active areas of the 60016 Diode P, 60017 Diode E, 60018 Diode SRS detectors are uniform to within approximately 5%. The 60019 microDiamond showed local variations up to 30%. The extra-cameral signal in the microDiamond was calculated from the side-on scan to be approximately 8% of the signal from the active element. The spatial response of four solid-state detectors has been measured. The technique yielded information about the location and uniformity of the active area, and the extra-cameral signal, for the beam quality used. © 2017 Commonwealth of Australia. Medical Physics © 2017 American Association of Physicists in Medicine. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced without prior written permission. Requests and enquiries concerning reproduction and rights should be directed in the first instance to John Wiley & Sons Ltd of The Atrium, Southern Gate, Chichester, West Sussex P019 8SQ UNITED KINGDOM; alternatively to ARPANSA.

Demonstration of motionless Knudsen pump based micro-gas chromatography featuring micro-fabricated columns and on-column detectors.

PubMed

Liu, Jing; Gupta, Naveen K; Wise, Kensall D; Gianchandani, Yogesh B; Fan, Xudong

2011-10-21

This paper reports the investigation of a micro-gas chromatography (μGC) system that utilizes an array of miniaturized motionless Knudsen pumps (KPs) as well as microfabricated separation columns and optical detectors. A prototype system was built to achieve a flow rate of 1 mL min(-1) and 0.26 mL min(-1) for helium and dry air, respectively, when they were used as carrier gas. This system was then employed to evaluate GC performance compromises and demonstrate the ability to separate and detect gas mixtures containing analytes of different volatilities and polarities. Furthermore, the use of pressure programming of the KP array was demonstrated to significantly shorten the analysis time while maintaining a high detection resolution. Using this method, we obtained a high resolution detection of 5 alkanes of different volatilities within 5 min. Finally, we successfully detected gas mixtures of various polarities using a tandem-column μGC configuration by installing two on-column optical detectors to obtain complementary chromatograms.

Computerized methodology for micro-CT and histological data inflation using an IVUS based translation map.

PubMed

Athanasiou, Lambros S; Rigas, George A; Sakellarios, Antonis I; Exarchos, Themis P; Siogkas, Panagiotis K; Naka, Katerina K; Panetta, Daniele; Pelosi, Gualtiero; Vozzi, Federico; Michalis, Lampros K; Parodi, Oberdan; Fotiadis, Dimitrios I

2015-10-01

A framework for the inflation of micro-CT and histology data using intravascular ultrasound (IVUS) images, is presented. The proposed methodology consists of three steps. In the first step the micro-CT/histological images are manually co-registered with IVUS by experts using fiducial points as landmarks. In the second step the lumen of both the micro-CT/histological images and IVUS images are automatically segmented. Finally, in the third step the micro-CT/histological images are inflated by applying a transformation method on each image. The transformation method is based on the IVUS and micro-CT/histological contour difference. In order to validate the proposed image inflation methodology, plaque areas in the inflated micro-CT and histological images are compared with the ones in the IVUS images. The proposed methodology for inflating micro-CT/histological images increases the sensitivity of plaque area matching between the inflated and the IVUS images (7% and 22% in histological and micro-CT images, respectively). Copyright © 2015 Elsevier Ltd. All rights reserved.

Frequency selective infrared optical filters for micro-bolometers

NASA Astrophysics Data System (ADS)

Creazzo, Timothy A.; Zablocki, Mathew J.; Zaman, Lenin; Sharkawy, Ahmed; Mirotznik, Mark S.; Prather, Dennis W.

2017-05-01

Current micro-bolometers are broadband detectors and tend to absorb a broad window of the IR spectrum for thermal imaging. Such systems are limited due to their lack of sensitivity to blackbody radiation, as well as the inability to spectrally discern multiple wavelengths in the field of view for hyperspectral imaging (HSI). As a result, many important applications such as low concentration chemical detection cannot be performed. One solution to this problem is to employ a system with thermoelectrically cooled or liquid nitrogen cooled sensors, which can lead to higher sensitivity in detection. However, one major drawback of these systems is the size, weight and power (SWaP) issue as they tend to be rather bulky and cumbersome, which largely challenges their use in unmanned aerial vehicles. Further, spectral filtering is commonly performed with large hardware and moving gratings, greatly increasing the SWaP of the system. To this point, Lumilant's effort is to develop wavelength selective uncooled IR filters that can be integrated onto a microbolometer, to exceed the sensitivity imposed by the blackbody radiation limit. We have demonstrated narrowband absorbers and electrically tunable filters addressing the need for low-SWaP platforms.

A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves.

PubMed

Wu, Heyu; Tai, Yuan-Chuan

2011-09-07

To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

Microscope mode secondary ion mass spectrometry imaging with a Timepix detector.

PubMed

Kiss, Andras; Jungmann, Julia H; Smith, Donald F; Heeren, Ron M A

2013-01-01

In-vacuum active pixel detectors enable high sensitivity, highly parallel time- and space-resolved detection of ions from complex surfaces. For the first time, a Timepix detector assembly was combined with a secondary ion mass spectrometer for microscope mode secondary ion mass spectrometry (SIMS) imaging. Time resolved images from various benchmark samples demonstrate the imaging capabilities of the detector system. The main advantages of the active pixel detector are the higher signal-to-noise ratio and parallel acquisition of arrival time and position. Microscope mode SIMS imaging of biomolecules is demonstrated from tissue sections with the Timepix detector.

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

NASA Astrophysics Data System (ADS)

Harsha Maramraju, Sri; Smith, S. David; Junnarkar, Sachin S.; Schulz, Daniela; Stoll, Sean; Ravindranath, Bosky; Purschke, Martin L.; Rescia, Sergio; Southekal, Sudeepti; Pratte, Jean-François; Vaska, Paul; Woody, Craig L.; Schlyer, David J.

2011-04-01

We developed a non-magnetic positron-emission tomography (PET) device based on the rat conscious animal PET that operates in a small-animal magnetic resonance imaging (MRI) scanner, thereby enabling us to carry out simultaneous PET/MRI studies. The PET detector comprises 12 detector blocks, each being a 4 × 8 array of lutetium oxyorthosilicate crystals (2.22 × 2.22 × 5 mm3) coupled to a matching non-magnetic avalanche photodiode array. The detector blocks, housed in a plastic case, form a 38 mm inner diameter ring with an 18 mm axial extent. Custom-built MRI coils fit inside the positron-emission tomography (PET) device, operating in transceiver mode. The PET insert is integrated with a Bruker 9.4 T 210 mm clear-bore diameter MRI scanner. We acquired simultaneous PET/MR images of phantoms, of in vivo rat brain, and of cardiac-gated mouse heart using [11C]raclopride and 2-deoxy-2-[18F]fluoro-d-glucose PET radiotracers. There was minor interference between the PET electronics and the MRI during simultaneous operation, and small effects on the signal-to-noise ratio in the MR images in the presence of the PET, but no noticeable visual artifacts. Gradient echo and high-duty-cycle spin echo radio frequency (RF) pulses resulted in a 7% and a 28% loss in PET counts, respectively, due to high PET counts during the RF pulses that had to be gated out. The calibration of the activity concentration of PET data during MR pulsing is reproducible within less than 6%. Our initial results demonstrate the feasibility of performing simultaneous PET and MRI studies in adult rats and mice using the same PET insert in a small-bore 9.4 T MRI.

Investigation of OPET Performance Using GATE, a Geant4-Based Simulation Software.

PubMed

Rannou, Fernando R; Kohli, Vandana; Prout, David L; Chatziioannou, Arion F

2004-10-01

A combined optical positron emission tomography (OPET) system is capable of both optical and PET imaging in the same setting, and it can provide information/interpretation not possible in single-mode imaging. The scintillator array here serves the dual function of coupling the optical signal from bioluminescence/fluorescence to the photodetector and also of channeling optical scintillations from the gamma rays. We report simulation results of the PET part of OPET using GATE, a Geant4 simulation package. The purpose of this investigation is the definition of the geometric parameters of the OPET tomograph. OPET is composed of six detector blocks arranged in a hexagonal ring-shaped pattern with an inner radius of 15.6 mm. Each detector consists of a two-dimensional array of 8 × 8 scintillator crystals each measuring 2 × 2 × 10 mm(3). Monte Carlo simulations were performed using the GATE software to measure absolute sensitivity, depth of interaction, and spatial resolution for two ring configurations, with and without gantry rotations, two crystal materials, and several crystal lengths. Images were reconstructed with filtered backprojection after angular interleaving and transverse one-dimensional interpolation of the sinogram. We report absolute sensitivities nearly seven times that of the prototype microPET at the center of field of view and 2.0 mm tangential and 2.3 mm radial resolutions with gantry rotations up to an 8.0 mm radial offset. These performance parameters indicate that the imaging spatial resolution and sensitivity of the OPET system will be suitable for high-resolution and high-sensitivity small-animal PET imaging.

Determination of small field synthetic single-crystal diamond detector correction factors for CyberKnife, Leksell Gamma Knife Perfexion and linear accelerator.

PubMed

Veselsky, T; Novotny, J; Pastykova, V; Koniarova, I

2017-12-01

The aim of this study was to determine small field correction factors for a synthetic single-crystal diamond detector (PTW microDiamond) for routine use in clinical dosimetric measurements. Correction factors following small field Alfonso formalism were calculated by comparison of PTW microDiamond measured ratio M Qclin fclin /M Qmsr fmsr with Monte Carlo (MC) based field output factors Ω Qclin,Qmsr fclin,fmsr determined using Dosimetry Diode E or with MC simulation itself. Diode measurements were used for the CyberKnife and Varian Clinac 2100C/D linear accelerator. PTW microDiamond correction factors for Leksell Gamma Knife (LGK) were derived using MC simulated reference values from the manufacturer. PTW microDiamond correction factors for CyberKnife field sizes 25-5 mm were mostly smaller than 1% (except for 2.9% for 5 mm Iris field and 1.4% for 7.5 mm fixed cone field). The correction of 0.1% and 2.0% for 8 mm and 4 mm collimators, respectively, needed to be applied to PTW microDiamond measurements for LGK Perfexion. Finally, PTW microDiamond M Qclin fclin /M Qmsr fmsr for the linear accelerator varied from MC corrected Dosimetry Diode data by less than 0.5% (except for 1 × 1 cm 2 field size with 1.3% deviation). Regarding low resulting correction factor values, the PTW microDiamond detector may be considered an almost ideal tool for relative small field dosimetry in a large variety of stereotactic and radiosurgery treatment devices. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

High accuracy position response calibration method for a micro-channel plate ion detector

NASA Astrophysics Data System (ADS)

Hong, R.; Leredde, A.; Bagdasarova, Y.; Fléchard, X.; García, A.; Müller, P.; Knecht, A.; Liénard, E.; Kossin, M.; Sternberg, M. G.; Swanson, H. E.; Zumwalt, D. W.

2016-11-01

We have developed a position response calibration method for a micro-channel plate (MCP) detector with a delay-line anode position readout scheme. Using an in situ calibration mask, an accuracy of 8 μm and a resolution of 85 μm (FWHM) have been achieved for MeV-scale α particles and ions with energies of ∼10 keV. At this level of accuracy, the difference between the MCP position responses to high-energy α particles and low-energy ions is significant. The improved performance of the MCP detector can find applications in many fields of AMO and nuclear physics. In our case, it helps reducing systematic uncertainties in a high-precision nuclear β-decay experiment.

Detection and differentiation of biological species using microcalorimetric spectroscopy.

PubMed

Arakawa, E T; Lavrik, N V; Rajic, S; Datskos, P G

2003-01-01

We report on the application of infrared (IR) microcalorimetric spectroscopy ( micro -CalSpec) to the identification and detection of trace amounts of biological species. Our approach combines principles of photothermal IR spectroscopy with ultrasensitive microcantilever (MC) thermal detectors. We have obtained photothermal IR spectra for DNA and RNA bases and for Bacillus Cereus (an anthrax simulant) in the wavelength range of 2.5-14.5 micro m (4000-690 cm(-1)). The measurements are accomplished by absorbing biological materials directly on a MC thermal detector. The main advantage of the developed micro -CalSpec is its unprecedented sensitivity as compared to any of the previously explored IR techniques, including FTIR and photothermal FTIR methods. Our results demonstrate that <10(-9)g of a biological sample is sufficient to obtain its characteristic micro -CalSpec spectrum that contains information-rich chemical (vibrational) signatures. This opens up a new opportunity to create inexpensive high-throughput analytical systems for biochemical detection.

Micro spectrometer for parallel light and method of use

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2011-01-01

A spectrometer system includes an optical assembly for collimating light, a micro-ring grating assembly having a plurality of coaxially-aligned ring gratings, an aperture device defining an aperture circumscribing a target focal point, and a photon detector. An electro-optical layer of the grating assembly may be electrically connected to an energy supply to change the refractive index of the electro-optical layer. Alternately, the gratings may be electrically connected to the energy supply and energized, e.g., with alternating voltages, to change the refractive index. A data recorder may record the predetermined spectral characteristic. A method of detecting a spectral characteristic of a predetermined wavelength of source light includes generating collimated light using an optical assembly, directing the collimated light onto the micro-ring grating assembly, and selectively energizing the micro-ring grating assembly to diffract the predetermined wavelength onto the target focal point, and detecting the spectral characteristic using a photon detector.

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

PubMed

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

2010-05-01

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

A new imaging method for understanding chemical dynamics: efficient slice imaging using an in-vacuum pixel detector.

PubMed

Jungmann, J H; Gijsbertsen, A; Visser, J; Visschers, J; Heeren, R M A; Vrakking, M J J

2010-10-01

The implementation of the Timepix complementary metal oxide semiconductor pixel detector in velocity map slice imaging is presented. This new detector approach eliminates the need for gating the imaging detector. In time-of-flight mode, the detector returns the impact position and the time-of-flight of charged particles with 12.5 ns resolution and a dynamic range of about 100 μs. The implementation of the Timepix detector in combination with a microchannel plate additionally allows for high spatial resolution information via center-of-mass centroiding. Here, the detector was applied to study the photodissociation of NO(2) at 452 nm. The energy resolution observed in the experiment was ΔE/E=0.05 and is limited by the experimental setup rather than by the detector assembly. All together, this new compact detector assembly is well-suited for slice imaging and is a promising tool for imaging studies in atomic and molecular physics research.

A Performance Comparison for Two Versions of the Vulcan Photometer

NASA Technical Reports Server (NTRS)

Borucki, W. J.; Caldwell, D. A.; Koch, D. G.; Jenkins, J. M.; Showen, R. L.

2001-01-01

Analysis of the images produced by the first version (V1) of the Vulcan photometer indicated that two major sources of noise were sky brightness and image motion. To reduce the effect of the sky brightness, a second version (V2) with a longer focal length and a larger format detector was developed and tested. The first version consisted of 15-centimeter (cm) focal length, F/1.5 Aerojet Delft reconnaissance lens, and a 2048 x 2048 format front-illuminated charged coupled device (CCD) with 9 microns micropixels (Mpixels). The second version used a 30-cm focal length, F/2.5 Kodak AeroEktar lens, and a 4096 x 4096 format CCD with 9 micro pixels. Both have a 49-square-degree field of view (FOV) but the area of the sky subtended by each pixel in the V2 version is one-fourth that of the V1 version. This modification substantially reduces the shot noise due to the sky background and allows fainter stars to be monitored for planetary transits. To remove the data gap and consequent signal-level change caused by flipping the photometer around the declination axis and to reduce image movement on the detector, several other modifications were incorporated. These include modifying the mount and stiffening the photometer and autoguider structures to reduce flexure. This paper compares the performance characteristics of each photometer and discusses tests to identify sources of systematic noise.

Imaging characteristics of the Extreme Ultraviolet Explorer microchannel plate detectors

NASA Technical Reports Server (NTRS)

Vallerga, J. V.; Kaplan, G. C.; Siegmund, O. H. W.; Lampton, M.; Malina, R. F.

1989-01-01

The Extreme Ultraviolet Explorer (EUVE) satellite will conduct an all-sky survey over the wavelength range from 70 A to 760 A using four grazing-incidence telescopes and seven microchannel-plate (MCP) detectors. The imaging photon-counting MCP detectors have active areas of 19.6 cm2. Photon arrival position is determined using a wedge-and-strip anode and associated pulse-encoding electronics. The imaging characteristics of the EUVE flight detectors are presented including image distortion, flat-field response, and spatial differential nonlinearity. Also included is a detailed discussion of image distortions due to the detector mechanical assembly, the wedge-and-strip anode, and the electronics. Model predictions of these distortions are compared to preflight calibration images which show distortions less than 1.3 percent rms of the detector diameter of 50 mm before correction. The plans for correcting these residual detector image distortions to less than 0.1 percent rms are also presented.

Systems, computer-implemented methods, and tangible computer-readable storage media for wide-field interferometry

NASA Technical Reports Server (NTRS)

Lyon, Richard G. (Inventor); Leisawitz, David T. (Inventor); Rinehart, Stephen A. (Inventor); Memarsadeghi, Nargess (Inventor)

2012-01-01

Disclosed herein are systems, computer-implemented methods, and tangible computer-readable storage media for wide field imaging interferometry. The method includes for each point in a two dimensional detector array over a field of view of an image: gathering a first interferogram from a first detector and a second interferogram from a second detector, modulating a path-length for a signal from an image associated with the first interferogram in the first detector, overlaying first data from the modulated first detector and second data from the second detector, and tracking the modulating at every point in a two dimensional detector array comprising the first detector and the second detector over a field of view for the image. The method then generates a wide-field data cube based on the overlaid first data and second data for each point. The method can generate an image from the wide-field data cube.

Documentation of the ISA Micro Computed Tomography System

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

Brown, William D.; Smith, Jerel A.

2013-12-18

This document is intended to provide information on the ISA Micro Computed Tomography (MicroCT) system that will be installed in Yavne, Israel. X-ray source, detector, and motion control hardware are specified as well as specimen platforms, containers, and reference material types. Most of the details on the system are derived from Reference 1 and 2.

Layout and first results of the nanotomography endstation at the P05 beamline at PETRA III

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

Ogurreck, M.; Greving, I.; Beckmann, F.

The Helmholtz-Zentrum Geesthacht operates the P05 Imaging Beamline at the DESY storage ring PETRA III. This beamline is dedicated to micro- and nanotomography with two endstations. This paper will present the nanotomography endstation layout and first results obtained from commissioning and test experiments. First tests have been performed with CRLs as X-ray objectives and newly developed rolled X-ray prism lenses as condenser optics. This setup allows a resolution of 100 nm half period with an effective detector pixel size of 15nm. A first tomograph of a photonic glass sample was measured in early 2014.

High Spectral Resolution, High Cadence, Imaging X-Ray Microcalorimeters for Solar Physics

NASA Technical Reports Server (NTRS)

Bandler, Simon R.; Bailey, Catherine N.; Bookbinder, Jay A.; DeLuca, Edward E.; Chervenak, Jay A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Daniel P.; Kelley, Richard L.; Kilbourne, Caroline A.;

Multi-wavelength observations of the solar atmosphere from the August 21, 2017 total solar eclipse

NASA Astrophysics Data System (ADS)

Tomczyk, S.; Boll, A.; Bryans, P.; Burkepile, J.; Casini, R.; DeLuca, E.; Gibson, K. L.; Judge, P. G.; McIntosh, S. W.; Samra, J.; Sewell, S. D.

2017-12-01

We will conduct three experiments at the August 21, 2017 total solar eclipse that we call the Rosetta Stone experiments. First, we will obtain narrow-bandpass images at infrared wavelengths of the magnetically sensitive coronal emission lines of Fe IX 2855 nm, Mg VIII 3028 nm and Si IX 3935 nm with a FLIR thermal imager. Information on the brightness of these lines is important for identifying the optimal lines for coronal magnetometry. These images will also serve as context images for the airborne AirSpec IR coronal spectroscopy experiment (Samra et al). Second, we will obtain linear polarization images of the visible emission lines of Fe X 637 nm and Fe XI 789 nm as well as the continuum polarization near 735 nm. These will be obtained with a novel detector with an integral array of linear micro-polarizers oriented at four different angles that enable polarization images without the need for liquid crystals or rotating elements. These measurements will provide information on the orientation of magnetic fields in the corona and serve to demonstrate the new detector technology. Lastly, we will obtain high cadence spectra as the moon covers and uncovers the chromosphere immediately after 2nd contact and before third contact. This so-called flash spectrum will be used to obtain information about chromospheric structure at a spatial resolution higher than is possible by other means. In this talk, we will describe the instrumentation used in these experiments and present initial results obtained with them. This work is supported by a grant from NASA, through NSF base funding of HAO/NCAR and by generous loans of equipment from our corporate partners, FLIR, 4D Technologies and Avantes.

Locating trace plutonium in contaminated soil using micro-XRF imaging

DOE PAGES

Worley, Christopher G.; Spencer, Khalil J.; Boukhalfa, Hakim; ...

2014-06-01

Micro-X-ray fluorescence (MXRF) was used to locate minute quantities of plutonium in contaminated soil. Because the specimen had previously been prepared for analysis by scanning electron microscopy, it was coated with gold to eliminate electron beam charging. However, this significantly hindered efforts to detect plutonium by MXRF. The gold L peak series present in all spectra increased background counts. Plutonium signal attenuation by the gold coating and severe peak overlap from potassium in the soil prevented detection of trace plutonium using the Pu Mα peak. However, the 14.3 keV Pu Lα peak sensitivity was not optimal due to poor transmissionmore » efficiency through the source polycapillary optic, and the instrument silicon drift detector sensitivity quickly declines for peaks with energies above ~10 keV. Instrumental parameters were optimized (eg. using appropriate source filters) in order to detect plutonium. An X-ray beam aperture was initially used to image a majority of the specimen with low spatial resolution. A small region that appeared to contain plutonium was then imaged at high spatial resolution using a polycapillary optic. Small areas containing plutonium were observed on a soil particle, and iron was co-located with the plutonium. Zinc and titanium also appeared to be correlated with the plutonium, and these elemental correlations provided useful plutonium chemical state information that helped to better understand its environmental transport properties.« less

Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography

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

Hall, G. N.; Izumi, N.; Landen, O. L.

2016-08-03

Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments, and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro channel plate) to provide gating and high DQE at the 40–200keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Here, experiments were performed atmore » energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.« less

Integrated infrared and visible image sensors

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Pain, Bedabrata (Inventor)

2000-01-01

Semiconductor imaging devices integrating an array of visible detectors and another array of infrared detectors into a single module to simultaneously detect both the visible and infrared radiation of an input image. The visible detectors and the infrared detectors may be formed either on two separate substrates or on the same substrate by interleaving visible and infrared detectors.

Modular reconfigurable matched spectral filter spectrometer

NASA Astrophysics Data System (ADS)

Schundler, Elizabeth; Engel, James R.; Gruber, Thomas; Vaillancourt, Robert; Benedict-Gill, Ryan; Mansur, David J.; Dixon, John; Potter, Kevin; Newbry, Scott

2015-06-01

OPTRA is currently developing a modular, reconfigurable matched spectral filter (RMSF) spectrometer for the monitoring of greenhouse gases. The heart of this spectrometer will be the RMSF core, which is a dispersive spectrometer that images the sample spectrum from 2000 - 3333 cm-1 onto a digital micro-mirror device (DMD) such that different columns correspond to different wavebands. By applying masks to this DMD, a matched spectral filter can be applied in hardware. The core can then be paired with different fore-optics or detector modules to achieve active in situ or passive remote detection of the chemicals of interest. This results in a highly flexible system that can address a wide variety of chemicals by updating the DMD masks and a wide variety of applications by swapping out fore-optic and detector modules. In either configuration, the signal on the detector is effectively a dot-product between the applied mask and the sample spectrum that can be used to make detection and quantification determinations. Using this approach significantly reduces the required data bandwidth of the sensor without reducing the information content, therefore making it ideal for remote, unattended systems. This paper will focus on the design of the RMSF core.

Characterization of a detector chain using a FPGA-based time-to-digital converter to reconstruct the three-dimensional coordinates of single particles at high flux

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

Nogrette, F.; Chang, R.; Bouton, Q.

We report on the development of a novel FPGA-based time-to-digital converter and its implementation in a detection chain that records the coordinates of single particles along three dimensions. The detector is composed of micro-channel plates mounted on top of a cross delay line and connected to fast electronics. We demonstrate continuous recording of the timing signals from the cross delay line at rates up to 4.1 × 10{sup 6} s{sup −1} and three-dimensional reconstruction of the coordinates up to 3.2 × 10{sup 6} particles per second. From the imaging of a calibrated structure we measure the in-plane resolution of themore » detector to be 140(20) μm at a flux of 3 × 10{sup 5} particles per second. In addition, we analyze a method to estimate the resolution without placing any structure under vacuum, a significant practical improvement. While we use UV photons here, the results of this work apply to the detection of other kinds of particles.« less

Designing a compact high performance brain PET scanner—simulation study

NASA Astrophysics Data System (ADS)

Gong, Kuang; Majewski, Stan; Kinahan, Paul E.; Harrison, Robert L.; Elston, Brian F.; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V.; Brefczynski-Lewis, Julie A.; Qi, Jinyi

2016-05-01

The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér-Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact ‘helmet’ design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging.

Designing a compact high performance brain PET scanner—simulation study

PubMed Central

Gong, Kuang; Majewski, Stan; Kinahan, Paul E; Harrison, Robert L; Elston, Brian F; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V; Brefczynski-Lewis, Julie A; Qi, Jinyi

2016-01-01

The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér–Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of- interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact ‘helmet’ design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging. PMID:27081753

Evaluation of a ''CMOS'' Imager for Shadow Mask Hard X-ray Telescope

NASA Technical Reports Server (NTRS)

Desai, Upendra D.; Orwig, Larry E.; Oergerle, William R. (Technical Monitor)

2002-01-01

We have developed a hard x-ray coder that provides high angular resolution imaging capability using a coarse position sensitive image plane detector. The coder consists of two Fresnel zone plates. (FZP) Two such 'FZP's generate Moire fringe patterns whose frequency and orientation define the arrival direction of a beam with respect to telescope axis. The image plane detector needs to resolve the Moire fringe pattern. Pixilated detectors can be used as an image plane detector. The recently available 'CMOS' imager could provide a very low power large area image plane detector for hard x-rays. We have looked into a unit made by Rad-Icon Imaging Corp. The Shadow-Box 1024 x-ray camera is a high resolution 1024xl024 pixel detector of 50x50 mm area. It is a very low power, stand alone camera. We present some preliminary results of our investigation of evaluation of such camera.

Radiography by selective detection of scatter field velocity components

NASA Technical Reports Server (NTRS)

Dugan, Edward T. (Inventor); Jacobs, Alan M. (Inventor); Shedlock, Daniel (Inventor)

2007-01-01

A reconfigurable collimated radiation detector, system and related method includes at least one collimated radiation detector. The detector has an adjustable collimator assembly including at least one feature, such as a fin, optically coupled thereto. Adjustments to the adjustable collimator selects particular directions of travel of scattered radiation emitted from an irradiated object which reach the detector. The collimated detector is preferably a collimated detector array, where the collimators are independently adjustable. The independent motion capability provides the capability to focus the image by selection of the desired scatter field components. When an array of reconfigurable collimated detectors is provided, separate image data can be obtained from each of the detectors and the respective images cross-correlated and combined to form an enhanced image.

Hardware, software, and scanning issues encountered during small animal imaging of photodynamic therapy in the athymic nude rat

NASA Astrophysics Data System (ADS)

Cross, Nathan; Sharma, Rahul; Varghai, Davood; Spring-Robinson, Chandra; Oleinick, Nancy L.; Muzic, Raymond F., Jr.; Dean, David

2007-02-01

Small animal imaging devices are now commonly used to study gene activation and model the effects of potential therapies. We are attempting to develop a protocol that non-invasively tracks the affect of Pc 4-mediated photodynamic therapy (PDT) in a human glioma model using structural image data from micro-CT and/or micro-MR scanning and functional data from 18F-fluorodeoxy-glucose (18F-FDG) micro-PET imaging. Methods: Athymic nude rat U87-derived glioma was imaged by micro-PET and either micro-CT or micro-MR prior to Pc 4-PDT. Difficulty insuring animal anesthesia and anatomic position during the micro-PET, micro-CT, and micro-MR scans required adaptation of the scanning bed hardware. Following Pc 4-PDT the animals were again 18F-FDG micro-PET scanned, euthanized one day later, and their brains were explanted and prepared for H&E histology. Histology provided the gold standard for tumor location and necrosis. The tumor and surrounding brain functional and structural image data were then isolated and coregistered. Results: Surprisingly, both the non-PDT and PDT groups showed an increase in tumor functional activity when we expected this signal to disappear in the group receiving PDT. Co-registration of the functional and structural image data was done manually. Discussion: As expected, micro-MR imaging provided better structural discrimination of the brain tumor than micro-CT. Contrary to expectations, in our preliminary analysis 18F-FDG micro-PET imaging does not readily discriminate the U87 tumors that received Pc 4-PDT. We continue to investigate the utility of micro-PET and other methods of functional imaging to remotely detect the specificity and sensitivity of Pc 4-PDT in deeply placed tumors.

Heteronuclear Micro-Helmholtz Coil Facilitates µm-Range Spatial and Sub-Hz Spectral Resolution NMR of nL-Volume Samples on Customisable Microfluidic Chips

PubMed Central

Spengler, Nils; Höfflin, Jens; Moazenzadeh, Ali; Mager, Dario; MacKinnon, Neil; Badilita, Vlad; Wallrabe, Ulrike; Korvink, Jan G.

2016-01-01

We present a completely revised generation of a modular micro-NMR detector, featuring an active sample volume of ∼ 100 nL, and an improvement of 87% in probe efficiency. The detector is capable of rapidly screening different samples using exchangeable, application-specific, MEMS-fabricated, microfluidic sample containers. In contrast to our previous design, the sample holder chips can be simply sealed with adhesive tape, with excellent adhesion due to the smooth surfaces surrounding the fluidic ports, and so withstand pressures of ∼2.5 bar, while simultaneously enabling high spectral resolution up to 0.62 Hz for H2O, due to its optimised geometry. We have additionally reworked the coil design and fabrication processes, replacing liquid photoresists by dry film stock, whose final thickness does not depend on accurate volume dispensing or precise levelling during curing. We further introduced mechanical alignment structures to avoid time-intensive optical alignment of the chip stacks during assembly, while we exchanged the laser-cut, PMMA spacers by diced glass spacers, which are not susceptible to melting during cutting. Doing so led to an overall simplification of the entire fabrication chain, while simultaneously increasing the yield, due to an improved uniformity of thickness of the individual layers, and in addition, due to more accurate vertical positioning of the wirebonded coils, now delimited by a post base plateau. We demonstrate the capability of the design by acquiring a 1H spectrum of ∼ 11 nmol sucrose dissolved in D2O, where we achieved a linewidth of 1.25 Hz for the TSP reference peak. Chemical shift imaging experiments were further recorded from voxel volumes of only ∼ 1.5nL, which corresponded to amounts of just 1.5 nmol per voxel for a 1 M concentration. To extend the micro-detector to other nuclei of interest, we have implemented a trap circuit, enabling heteronuclear spectroscopy, demonstrated by two 1H/13C 2D HSQC experiments. PMID:26730968

Parallel detecting super-resolution microscopy using correlation based image restoration

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Antenna-coupled transition-edge hot-electron microbolometers

NASA Astrophysics Data System (ADS)

Ali, Shafinaz; Timbie, Peter T.; Malu, Siddharth; McCammon, Dan; Nelms, Kari L.; Pathak, Rashmi; van der Weide, Daniel W.; Allen, Christine A.; Abrahams, J.; Chervenak, James A.; Hsieh, Wen-Ting; Miller, Timothy M.; Moseley, S. H., Jr.; Stevenson, Thomas R.; Wollack, Edward J.

2004-10-01

We are developing a new type of detector for observational cosmology and astrophysical research. Incoming radiation from the sky is coupled to a superconducting microstrip transmission line that terminates in a thin film absorber. At sub-Kelvin temperature, the thermal isolation between the electrons and the lattice makes it possible for the electrons in the small absorber (100's of cubic micro-meter) and superconducting bilayer (Transition Edge Sensor) to heat up by the radiation absorbed by the electrons of the normal absorbing layer. We call this detector a Transition-edge Hot-electron Micro-bolometer (THM). THMs can be fabricated by photo lithography, so it is relatively easy to make matched detectors for a large focal plane array telescope. We report on the thermal properties of Mo/Au THMs with Bi/Au absorbers.

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

PubMed

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

2014-01-01

To investigate whether the integrated circuit (IC) detector results in reduced noise in computed tomography (CT) colonography (CTC). Three hundred sixty-six consecutive patients underwent clinically indicated CTC using the same CT scanner system, except for a difference in CT detectors (IC or conventional). Image noise, patient size, and scanner radiation output (volume CT dose index) were quantitatively compared between patient cohorts using each detector system, with separate comparisons for the abdomen and pelvis. For the abdomen and pelvis, despite significantly larger patient sizes in the IC detector cohort (both P < 0.001), image noise was significantly lower (both P < 0.001), whereas volume CT dose index was unchanged (both P > 0.18). Based on the observed image noise reduction, radiation dose could alternatively be reduced by approximately 20% to result in similar levels of image noise. Computed tomography colonography images acquired using the IC detector had significantly lower noise than images acquired using the conventional detector. This noise reduction can permit further radiation dose reduction in CTC.

Theoretical and Monte Carlo optimization of a stacked three-layer flat-panel x-ray imager for applications in multi-spectral diagnostic medical imaging

NASA Astrophysics Data System (ADS)

Lopez Maurino, Sebastian; Badano, Aldo; Cunningham, Ian A.; Karim, Karim S.

2016-03-01

We propose a new design of a stacked three-layer flat-panel x-ray detector for dual-energy (DE) imaging. Each layer consists of its own scintillator of individual thickness and an underlying thin-film-transistor-based flat-panel. Three images are obtained simultaneously in the detector during the same x-ray exposure, thereby eliminating any motion artifacts. The detector operation is two-fold: a conventional radiography image can be obtained by combining all three layers' images, while a DE subtraction image can be obtained from the front and back layers' images, where the middle layer acts as a mid-filter that helps achieve spectral separation. We proceed to optimize the detector parameters for two sample imaging tasks that could particularly benefit from this new detector by obtaining the best possible signal to noise ratio per root entrance exposure using well-established theoretical models adapted to fit our new design. These results are compared to a conventional DE temporal subtraction detector and a single-shot DE subtraction detector with a copper mid-filter, both of which underwent the same theoretical optimization. The findings are then validated using advanced Monte Carlo simulations for all optimized detector setups. Given the performance expected from initial results and the recent decrease in price for digital x-ray detectors, the simplicity of the three-layer stacked imager approach appears promising to usher in a new generation of multi-spectral digital x-ray diagnostics.

Development of ultrahigh resolution alpha particle imaging detector using 1 mm channel size Si-PM array

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Kawaguchi, Wataru

2018-06-01

For precise distribution measurements of alpha particles, a high-resolution alpha particle imaging detector is required. Although combining a thin scintillator with a silicon photomultiplier (Si-PM) array is a promising method for achieving high resolution, the spatial resolution is limited. Reducing the size of the Si-PM array is a possible approach to improving the spatial resolution of the alpha particle imaging detector. Consequently, we employed a 1 mm channel size Si-PM array combined with a thin ZnS(Ag) sheet to form an alpha particle imaging detector and evaluated the performance. For the developed alpha particle imaging detector, an Si-PM array with 1 mm x 1 mm channel size arranged 8 x 8 was optically coupled to a ZnS(Ag) sheet with a 1-mm-thick light guide between them. The size of the alpha particle imaging detector was 9.5 mm x 9.5 mm. The spatial resolution of the developed alpha particle imaging detector was 0.14 mm FWHM, and the energy resolution was 74% FWHM for 5.5 MeV alpha particles. The uniformity of the imaging detector at the central part of the field of view (FOV) was ±4.7%. The background count rate was 0.06 counts/min. We obtained various high-resolution phantom images for alpha particles with the developed system. We conclude that the developed imaging detector is promising for high-resolution distribution measurements of alpha particles.

The Far Ultra-Violet Imager on the Icon Mission

NASA Astrophysics Data System (ADS)

Mende, S. B.; Frey, H. U.; Rider, K.; Chou, C.; Harris, S. E.; Siegmund, O. H. W.; England, S. L.; Wilkins, C.; Craig, W.; Immel, T. J.; Turin, P.; Darling, N.; Loicq, J.; Blain, P.; Syrstad, E.; Thompson, B.; Burt, R.; Champagne, J.; Sevilla, P.; Ellis, S.

2017-10-01

ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N2 ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of O+ ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a Czerny-Turner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to overcome the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON FUV meets its design requirements and is ready to be launched on the ICON spacecraft.

Reconstruction of color images via Haar wavelet based on digital micromirror device

NASA Astrophysics Data System (ADS)

Liu, Xingjiong; He, Weiji; Gu, Guohua

2015-10-01

A digital micro mirror device( DMD) is introduced to form Haar wavelet basis , projecting on the color target image by making use of structured illumination, including red, green and blue light. The light intensity signals reflected from the target image are received synchronously by the bucket detector which has no spatial resolution, converted into voltage signals and then transferred into PC[1] .To reach the aim of synchronization, several synchronization processes are added during data acquisition. In the data collection process, according to the wavelet tree structure, the locations of significant coefficients at the finer scale are predicted by comparing the coefficients sampled at the coarsest scale with the threshold. The monochrome grayscale images are obtained under red , green and blue structured illumination by using Haar wavelet inverse transform algorithm, respectively. The color fusion algorithm is carried on the three monochrome grayscale images to obtain the final color image. According to the imaging principle, the experimental demonstration device is assembled. The letter "K" and the X-rite Color Checker Passport are projected and reconstructed as target images, and the final reconstructed color images have good qualities. This article makes use of the method of Haar wavelet reconstruction, reducing the sampling rate considerably. It provides color information without compromising the resolution of the final image.

Design and Operation of A Setup with A Camera and Adjustable Mirror to Inspect the Sense-Wire Planes of the Time Projection Chamber Inside the MicroBooNE Cryostat

DOE PAGES

Carls, Benjamin; Horton-Smith, Glenn; James, Catherine C.; ...

2015-08-26

Detectors in particle physics, particularly when including cryogenic components, are often enclosed in vessels that do not provide any physical or visual access to the detectors themselves after installation. However, it can be desirable for experiments to visually investigate the inside of the vessel. The MicroBooNE cryostat hosts a TPC with sense-wire planes, which had to be inspected for damage such as breakage or sagging. This inspection was performed after the transportation of the vessel with the enclosed detector to its final location, but before filling with liquid argon. Our paper describes an approach to view the inside of themore » MicroBooNE cryostat with a setup of a camera and a mirror through one of its cryogenic service nozzles. The paper also describes the camera and mirror chosen for the operation, the illumination, and the mechanical structure of the setup. It explains how the system was operated and demonstrates its performance.« less

The CosmicWatch Desktop Muon Detector: a self-contained, pocket sized particle detector

NASA Astrophysics Data System (ADS)

Axani, S. N.; Frankiewicz, K.; Conrad, J. M.

2018-03-01

The CosmicWatch Desktop Muon Detector is a self-contained, hand-held cosmic ray muon detector that is valuable for astro/particle physics research applications and outreach. The material cost of each detector is under 100 and it takes a novice student approximately four hours to build their first detector. The detectors are powered via a USB connection and the data can either be recorded directly to a computer or to a microSD card. Arduino- and Python-based software is provided to operate the detector and an online application to plot the data in real-time. In this paper, we describe the various design features, evaluate the performance, and illustrate the detectors capabilities by providing several example measurements.

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

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

Sjoeberg, J; Bujila, R; Omar, A

2015-06-15

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

Dual Functional Roles of Molecular Beacon as a MicroRNA Detector and Inhibitor*

PubMed Central

Li, Wai Ming; Chan, Ching-Man; Miller, Andrew L.; Lee, Chow H.

2017-01-01

MicroRNAs are essential in many cellular processes. The ability to detect microRNAs is important for understanding its function and biogenesis. This study is aimed at using a molecular beacon to detect miR-430 in developing zebrafish embryos as a proof of principle. miR-430 is crucial for the clearance of maternal mRNA during maternal zygotic transition in embryonic development. Despite its known function, the temporal and spatial expression of miR-430 remains unclear. We used various imaging techniques, including laser scanning confocal microscopy, spinning disk, and lightsheet microscopy, to study the localization of miR-430 and any developmental defects possibly caused by the molecular beacon. Our results show that miR-430 is expressed early in development and is localized in distinct cytoplasmic granules where its target mRNA can be detected. We also show that the designed molecular beacon can inhibit the function of miR-430 and cause developmental defect in the brain, notochord, heart, and kidney, depending on the delivery site within the embryo, suggesting that miR-430 plays a diverse role in embryonic morphogenesis. When compared with morpholino, molecular beacon is 2 orders of magnitude more potent in inhibiting miR-430. Thus, our results reveal that in addition to being used as a valuable tool for the detection of microRNAs in vivo, molecular beacons can also be employed to inhibit microRNAs in a specific manner. PMID:28100783

Development of Individually Addressable Micro-Mirror-Arrays for Space Applications

NASA Technical Reports Server (NTRS)

Dutta, Sanghamitra B.; Ewin, Audrey J.; Jhabvala, Murzy; Kotecki, Carl A.; Kuhn, Jonathan L.; Mott, D. Brent

2000-01-01

We have been developing a 32 x 32 prototype array of individually addressable Micro-Mirrors capable of operating at cryogenic temperature for Earth and Space Science applications. Micro-Mirror-Array technology has the potential to revolutionize imaging and spectroscopy systems for NASA's missions of the 21st century. They can be used as programmable slits for the Next Generation Space Telescope, as smart sensors for a steerable spectrometer, as neutral density filters for bright scene attenuation etc. The, entire fabrication process is carried out in the Detector Development Laboratory at NASA, GSFC. The fabrication process is low temperature compatible and involves integration of conventional CMOS technology and surface micro-machining used in MEMS. Aluminum is used as the mirror material and is built on a silicon substrate containing the CMOS address circuit. The mirrors are 100 microns x l00 microns in area and deflect by +/- 10 deg induced by electrostatic actuation between two parallel plate capacitors. A pair of thin aluminum torsion straps allow the mirrors to tilt. Finite-element-analysis and closed form solutions using electrostatic and mechanical torque for mirror operation were developed and the results were compared with laboratory performance. The results agree well both at room temperature and at cryogenic temperature. The development demonstrates the first cryogenic operation of two-dimensional Micro-Mirrors with bi-state operation. Larger arrays will be developed meeting requirements for different science applications. Theoretical analysis, fabrication process, laboratory test results and different science applications will be described in detail.

Chip-based device for parallel sorting, amplification, detection, and identification of nucleic acid subsequences

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

Beer, Neil Reginald; Colston, Jr, Billy W.

An apparatus for chip-based sorting, amplification, detection, and identification of a sample having a planar substrate. The planar substrate is divided into cells. The cells are arranged on the planar substrate in rows and columns. Electrodes are located in the cells. A micro-reactor maker produces micro-reactors containing the sample. The micro-reactor maker is positioned to deliver the micro-reactors to the planar substrate. A microprocessor is connected to the electrodes for manipulating the micro-reactors on the planar substrate. A detector is positioned to interrogate the sample contained in the micro-reactors.

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

PubMed

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

2013-10-01

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

A micro GC detector array based on chemiresistors employing various surface functionalized monolayer-protected gold nanoparticles.

PubMed

Jian, Rih-Sheng; Huang, Rui-Xuan; Lu, Chia-Jung

2012-01-15

Aspects of the design, fabrication, and characterization of a chemiresistor type of microdetector for use in conjunction with gas chromatograph are described. The detector was manufactured on silicon chips using microelectromechanical systems (MEMS) technology. Detection was based on measuring changes in resistance across a film comprised of monolayer-protected gold nanoclusters (MPCs). When chromatographic separated molecules entered the detector cell, the MPC film absorbed vapor and undergoes swelling, then the resistance changes accordingly. Thiolates were used as ligand shells to encapsulate the nano-gold core and to manipulate the selectivity of the detector array. The dimensions of the μ-detector array were 14(L)×3.9(W)×1.2(H)mm. Mixtures of eight volatile organic compounds with different functional groups and volatility were tested to characterize the selectivity of the μ-detector array. The detector responses were rapid, reversible, and linear for all of the tested compounds. The detection limits ranged from 2 to 111ng, and were related to both the compound volatility and the selectivity of the surface ligands on the gold nanoparticles. Design and operation parameters such as flow rate, detector temperature, and width of the micro-fluidic channel were investigated. Reduction of the detector temperature resulted in improved sensitivity due to increased absorption. When a wider flow channel was used, the signal-to-noise ratio was improved due to the larger sensing area. The extremely low power consumption and small size makes this μ-detector array potentially useful for the development of integrated μ-GC. Copyright © 2011 Elsevier B.V. All rights reserved.

Raman microspectroscopy of optically trapped micro- and nanoobjects

NASA Astrophysics Data System (ADS)

Jonáš, Alexandr; Ježek, Jan; Šerý, Mojmír; Zemánek, Pavel

2008-12-01

We describe and characterize an experimental system for Raman microspectroscopy of micro- and nanoobjects optically trapped in aqueous suspensions with the use of a single-beam gradient optical trap (Raman tweezers). This system features two separate lasers providing light for the optical trapping and excitation of the Raman scattering spectra from the trapped specimen, respectively. Using independent laser beams for trapping and spectroscopy enables optimizing the parameters of both beams for their respective purposes. Moreover, it is possible to modulate the position of the trapped object relative to the Raman beam focus for maximizing the detected Raman signal and obtaining spatially resolved images of the trapped specimen. Using this experimental system, we have obtained Raman scattering spectra of individual optically confined micron and sub-micron sized polystyrene beads and baker's yeast cells. Sufficiently high signal-to-noise ratio of the spectra could be achieved using a few tens of milliwatts of the Raman beam power and detector integration times on the order of seconds.

A junction-level optoelectronic characterization of etching-induced damage for third-generation HgCdTe infrared focal-plane array photodetectors

NASA Astrophysics Data System (ADS)

Wang, Peng; Wang, Yueming; Wu, Mingzai; Ye, Zhenhua

2018-06-01

Third-generation HgCdTe-based infrared focal plane arrays require high aspect ratio trenches with admissible etch induced damage at the surface and sidewalls for effectively isolating the pixels. In this paper, the high-density inductively coupled plasma enhanced reaction ion etching technique has been used for micro-mesa delineation of HgCdTe for third-generation infrared focal-plane array detectors. A nondestructive junction-level optoelectronic characterization method called laser beam induced current (LBIC) is used to evaluate the lateral junction extent of HgCdTe etch-induced damage scanning electron microscopy. It is found that the LBIC profiles exhibit evident double peaks and valleys phenomena. The lateral extent of etch induced mesa damage of ∼2.4 μm is obtained by comparing the LBIC profile and the scanning electron microscopy image of etched sample. This finding will guide us to nondestructively identify the distributions of the etching damages in large scale HgCdTe micro-mesa.

Recent developments in photodetection for medical applications

NASA Astrophysics Data System (ADS)

Llosá, Gabriela

2015-07-01

The use of the most advanced technology in medical imaging results in the development of high performance detectors that can significantly improve the performance of the medical devices employed in hospitals. Scintillator crystals coupled to photodetectors remain to be essential detectors in terms of performance and cost for medical imaging applications in different imaging modalities. Recent advances in photodetectors result in an increase of the performance of the medical scanners. Solid state detectors can provide substantial performance improvement, but are more complex to integrate into clinical detectors due mainly to their higher cost. Solid state photodetectors (APDs, SiPMs) have made new detector concepts possible and have led to improvements in different imaging modalities. Recent advances in detectors for medical imaging are revised.

UDCM Operating Procedure (Limited Functionality prototype)

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

Newell, Matthew R.

2016-06-14

The UDCM is a two channel low current measurement device designed to record sub-nano-amp to micro-amp currents from radiation detectors. The UDCM incorporates a Commercial-Off-The- Shelf (COTS) processor enabling both serial over USB as well as Ethernet communications. The instrument includes microSD and USB flash memory for data storage as well as a programmable High Voltage (HV) power supply for detector bias. The UDCM incorporates a unique TTL output feature first used in the LANL Current to Pulse Converter (CPC). Two SMA connectors on the UDCM provide TTL pulses at a frequency proportional to the input currents.

Large scale infrared imaging of tissue micro arrays (TMAs) using a tunable Quantum Cascade Laser (QCL) based microscope.

PubMed

Bassan, Paul; Weida, Miles J; Rowlette, Jeremy; Gardner, Peter

2014-08-21

Chemical imaging in the field of vibrational spectroscopy is developing into a promising tool to complement digital histopathology. Applications include screening of biopsy tissue via automated recognition of tissue/cell type and disease state based on the chemical information from the spectrum. For integration into clinical practice, data acquisition needs to be speeded up to implement a rack based system where specimens are rapidly imaged to compete with current visible scanners where 100's of slides can be scanned overnight. Current Fourier transform infrared (FTIR) imaging with focal plane array (FPA) detectors are currently the state-of-the-art instrumentation for infrared absorption chemical imaging, however recent development in broadly tunable lasers in the mid-IR range is considered the most promising potential candidate for next generation microscopes. In this paper we test a prototype quantum cascade laser (QCL) based spectral imaging microscope with a focus on discrete frequency chemical imaging. We demonstrate how a protein chemical image of the amide I band (1655 cm(-1)) of a 2 × 2.4 cm(2) breast tissue microarray (TMA) containing over 200 cores can be measured in 9 min. This result indicates that applications requiring chemical images from a few key wavelengths would be ideally served by laser-based microscopes.

Measurements with Si and GaAs pixel detectors bonded to photon counting readout chips

NASA Astrophysics Data System (ADS)

Schwarz, C.; Campbell, M.; Goeppert, R.; Ludwig, J.; Mikulec, B.; Runge, K.; Smith, K. M.; Snoeys, W.

2001-06-01

Detectors fabricated with SI-GaAs and Si bulk material were bonded to Photon Counting Chips (PCC), developed in the framework of the MEDIPIX Collaboration. The PCC consists of a matrix of 64×64 identical square pixels (170 μm×170 μm) with a 15-bit counter in each cell. We investigated the imaging properties of these detector systems under exposure of a dental X-ray tube at room temperature. The image homogeneity and the mean count rate were determined via flood exposure images and compared. Exposures for GaAs detectors exhibit a 3 times larger spread in count rate per image in comparison to Si detectors. This also results in a 3 times worse signal to noise ratio. IV-characteristics and X-ray images at different values of the detectors bias voltage were also taken and show a 30 times higher leakage current for GaAs. The Si detector is fully active beginning from 70 V, whereas the GaAs detector does not reach full charge collection. The presampling modulation transfer function of both assembly types was measured via slit images and gives a spatial resolution of 4.3 lp/mm for both detector systems.

Method for growing a back surface contact on an imaging detector used in conjunction with back illumination

NASA Technical Reports Server (NTRS)

Blacksberg, Jordana (Inventor); Hoenk, Michael Eugene (Inventor); Nikzad, Shouleh (Inventor)

2010-01-01

A method is provided for growing a back surface contact on an imaging detector used in conjunction with back illumination. In operation, an imaging detector is provided. Additionally, a back surface contact (e.g. a delta-doped layer, etc.) is grown on the imaging detector utilizing a process that is performed at a temperature less than 450 degrees Celsius.

Determination of the KQclinfclin,Qmsr fmsr correction factors for detectors used with an 800 MU/min CyberKnife(®) system equipped with fixed collimators and a study of detector response to small photon beams using a Monte Carlo method.

PubMed

Moignier, C; Huet, C; Makovicka, L

2014-07-01

In a previous work, output ratio (ORdet) measurements were performed for the 800 MU/min CyberKnife(®) at the Oscar Lambret Center (COL, France) using several commercially available detectors as well as using two passive dosimeters (EBT2 radiochromic film and micro-LiF TLD-700). The primary aim of the present work was to determine by Monte Carlo calculations the output factor in water (OFMC,w) and the [Formula: see text] correction factors. The secondary aim was to study the detector response in small beams using Monte Carlo simulation. The LINAC head of the CyberKnife(®) was modeled using the PENELOPE Monte Carlo code system. The primary electron beam was modeled using a monoenergetic source with a radial gaussian distribution. The model was adjusted by comparisons between calculated and measured lateral profiles and tissue-phantom ratios obtained with the largest field. In addition, the PTW 60016 and 60017 diodes, PTW 60003 diamond, and micro-LiF were modeled. Output ratios with modeled detectors (ORMC,det) and OFMC,w were calculated and compared to measurements, in order to validate the model for smallest fields and to calculate [Formula: see text] correction factors, respectively. For the study of the influence of detector characteristics on their response in small beams; first, the impact of the atomic composition and the mass density of silicon, LiF, and diamond materials were investigated; second, the material, the volume averaging, and the coating effects of detecting material on the detector responses were estimated. Finally, the influence of the size of silicon chip on diode response was investigated. Looking at measurement ratios (uncorrected output factors) compared to the OFMC,w, the PTW 60016, 60017 and Sun Nuclear EDGE diodes systematically over-responded (about +6% for the 5 mm field), whereas the PTW 31014 Pinpoint chamber systematically under-responded (about -12% for the 5 mm field). ORdet measured with the SFD diode and PTW 60003 diamond detectors were in good agreement with OFMC,w except for the 5 mm field size (about -7.5% for the diamond and +3% for the SFD). A good agreement with OFMC,w was obtained with the EBT2 film and micro-LiF dosimeters (deviation less than 1.4% for all fields investigated). [Formula: see text] correction factors for several detectors used in this work have been calculated. The impact of atomic composition on the dosimetric response of detectors was found to be insignificant, unlike the mass density and size of the detecting material. The results obtained with the passive dosimeters showed that they can be used for small beam OF measurements without correction factors. The study of detector response showed that ORdet is depending on the mass density, the volume averaging, and the coating effects of the detecting material. Each effect was quantified for the PTW 60016 and 60017 diodes, the micro-LiF, and the PTW 60003 diamond detectors. None of the active detectors used in this work can be recommended as a reference for small field dosimetry, but an improved diode detector with a smaller silicon chip coated with tissue-equivalent material is anticipated (by simulation) to be a reliable small field dosimetric detector in a nonequilibrium field.

Determination of the active volumes of solid-state photon-beam dosimetry detectors using the PTB proton microbeam.

PubMed

Poppinga, Daniela; Delfs, Bjoern; Meyners, Jutta; Langner, Frank; Giesen, Ulrich; Harder, Dietrich; Poppe, Bjoern; Looe, Hui K

2018-05-04

This study aims at the experimental determination of the diameters and thicknesses of the active volumes of solid-state photon-beam detectors for clinical dosimetry. The 10 MeV proton microbeam of the PTB (Physikalisch-Technische Bundesanstalt, Braunschweig) was used to examine two synthetic diamond detectors, type microDiamond (PTW Freiburg, Germany), and the silicon detectors Diode E (PTW Freiburg, Germany) and Razor Diode (Iba Dosimetry, Germany). The knowledge of the dimensions of their active volumes is essential for their Monte Carlo simulation and their applications in small-field photon-beam dosimetry. The diameter of the active detector volume was determined from the detector current profile recorded by radially scanning the proton microbeam across the detector. The thickness of the active detector volume was determined from the detector's electrical current, the number of protons incident per time interval and their mean stopping power in the active volume. The mean energy of the protons entering this volume was assessed by comparing the measured and the simulated influence of the thickness of a stack of aluminum preabsorber foils on the detector signal. For all detector types investigated, the diameters measured for the active volume closely agreed with the manufacturers' data. For the silicon Diode E detector, the thickness determined for the active volume agreed with the manufacturer's data, while for the microDiamond detectors and the Razor Diode, the thicknesses measured slightly exceeded those stated by the manufacturers. The PTB microbeam facility was used to analyze the diameters and thicknesses of the active volumes of photon dosimetry detectors for the first time. A new method of determining the thickness values with an uncertainty of ±10% was applied. The results appear useful for further consolidating detailed geometrical knowledge of the solid-state detectors investigated, which are used in clinical small-field photon-beam dosimetry. © 2018 American Association of Physicists in Medicine.

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

Russ, M; Shankar, A; Lau, A

Purpose: Demonstrate and quantify the augmented resolution due to focalspot size decrease in images acquired on the anode side of the field, for both small and medium (0.3 and 0.6mm) focal-spot sizes using the experimental task-based GM-ROD metric. Theoretical calculations have shown that a medium focal-spot can achieve the resolution of a small focal-spot if acquired with a tilted anode, effectively providing a higher-output small focal-spot. Methods: The MAF-CMOS (micro-angiographic fluoroscopic complementary-metal-oxide semiconductor) detector (75µm pixel pitch) imaged two copper wire segments of different diameter and a pipeline stent at the central axis and on the anode side of themore » beam, achieved by tilting the x-ray C-arm (Toshiba Infinix) to 6° and realigning the detector with the perpendicular ray to correct for x-ray obliquity. The relative gain in resolution was determined using the GM-ROD metric, which compares images on the basis of the Fourier transform of the image and the measured NNPS. To emphasize the geometric unsharpness, images were acquired at a magnification of two. Results: Images acquired on the anode side were compared to those acquired on the central axis with the same target-area focal-spot to consider the effect of an angled tube, and for all three objects the advantage of the smaller effective focal-spot was clear, showing a maximum improvement of 36% in GM-ROD. The images obtained with the small focal-spot at the central axis were compared to those of the medium focal-spot at the anode side and, for all objects, the relative performance was comparable. Conclusion: For three objects, the GM-ROD demonstrated the advantage of the anode side focal-spot. The comparable performance of the medium focal-spot on the anode side will allow for a high-output small focal-spot; a necessity in endovascular image-guided interventions. Partial support from an NIH grant R01EB002873 and an equipment grant from Toshiba Medical Systems Corp.« less

Comparison of morphological and conventional edge detectors in medical imaging applications

NASA Astrophysics Data System (ADS)

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

1991-06-01

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

Methods for increasing the sensitivity of gamma-ray imagers

DOEpatents

Mihailescu, Lucian [Pleasanton, CA; Vetter, Kai M [Alameda, CA; Chivers, Daniel H [Fremont, CA

2012-02-07

Methods are presented that increase the position resolution and granularity of double sided segmented semiconductor detectors. These methods increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

New Thermal Infrared Hyperspectral Imagers

DTIC Science & Technology

2009-10-01

involve imaging systems based on both MCT and microbolometer detector . All the systems base on push-broom imaging spectrograph with transmission grating...application requirements. The studies involve imaging systems based on both MCT and microbolometer detector . All the systems base on push-broom...remote sensing imager utilizes MCT detector combined with BMC-technique (background monitoring on-chip), background suppression and temperature

Systems for increasing the sensitivity of gamma-ray imagers

DOEpatents

Mihailescu, Lucian; Vetter, Kai M.; Chivers, Daniel H.

2012-12-11

Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

Low dark current MCT-based focal plane detector arrays for the LWIR and VLWIR developed at AIM

NASA Astrophysics Data System (ADS)

Gassmann, Kai Uwe; Eich, Detlef; Fick, Wolfgang; Figgemeier, Heinrich; Hanna, Stefan; Thöt, Richard

2015-10-01

For nearly 40 years AIM develops, manufactures and delivers photo-voltaic and photo-conductive infrared sensors and associated cryogenic coolers which are mainly used for military applications like pilotage, weapon sights, UAVs or vehicle platforms. In 2005 AIM started to provide the competences also for space applications like IR detector units for the SLSTR instrument on board of the Sentinel 3 satellite, the hyperspectral SWIR Imager for EnMAP or pushbroom detectors for high resolution Earth observation satellites. Meanwhile AIM delivered more than 25 Flight Models for several customers. The first European pulse-tube cooler ever operating on-board of a satellite is made by AIM. AIM homes the required infrared core capabilities such as design and manufacturing of focal plane assemblies, detector housing technologies, development and manufacturing of cryocoolers and also data processing for thermal IR cameras under one roof which enables high flexibility to react to customer needs and assures economical solutions. Cryogenically cooled Hg(1-x)CdxTe (MCT) quantum detectors are unequalled for applications requiring high imaging as well as high radiometric performance in the infrared spectral range. Compared with other technologies, they provide several advantages, such as the highest quantum efficiency, lower power dissipation compared to photoconductive devices and fast response times, hence outperforming micro-bolometer arrays. However, achieving an excellent MCT detector performance at long (LWIR) and very long (VLWIR) infrared wavelengths is challenging due to the exponential increase in the thermally generated photodiode dark current with increasing cut-off wavelength and / or operating temperature. Dark current is a critical design driver, especially for LWIR / VLWIR multi-spectral imagers with moderate signal levels or hyper-spectral Fourier spectrometers operating deep into the VLWIR spectral region. Consequently, low dark current (LDC) technologies are the prerequisite for future scientific space and earth observation missions. Aiming, for example at exoplanet or earth atmospheric spectral analysis, significant improvement in LWIR / VLWIR detector material performance is mandatory. LDC material optimization can target different directions of impact: (i) reduction of dark current for a given operational temperature to increase SNR and reduce thermally induced signal offset variations. (ii) operation at elevated temperatures at a given dark current level to reduce mass and power budget of the required cryocooler and to reduce cryostat complexity. (iii) increase the accessible cut-off wavelength at constant detector temperature and dark current level. This paper presents AIM's latest results on n-on-p as well as p-on-n low dark current planar MCT photodiode focal plane detector arrays at cut-off wavelengths >11 μm at 80 K. Dark current densities below Tennant's `Rule07'1 have been demonstrated for n-on-p and p-on-n devices. This work has been carried out under ESA contract ESTEC 4000107414/13/NL/SFe².

Photoacoustic projection imaging using an all-optical detector array

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Tomographic imaging using poissonian detector data

DOEpatents

Aspelmeier, Timo; Ebel, Gernot; Hoeschen, Christoph

2013-10-15

An image reconstruction method for reconstructing a tomographic image (f.sub.j) of a region of investigation within an object (1), comprises the steps of providing detector data (y.sub.i) comprising Poisson random values measured at an i-th of a plurality of different positions, e.g. i=(k,l) with pixel index k on a detector device and angular index l referring to both the angular position (.alpha..sub.l) and the rotation radius (r.sub.l) of the detector device (10) relative to the object (1), providing a predetermined system matrix A.sub.ij assigning a j-th voxel of the object (1) to the i-th detector data (y.sub.i), and reconstructing the tomographic image (f.sub.j) based on the detector data (y.sub.i), said reconstructing step including a procedure of minimizing a functional F(f) depending on the detector data (y.sub.i) and the system matrix A.sub.ij and additionally including a sparse or compressive representation of the object (1) in an orthobasis T, wherein the tomographic image (f.sub.j) represents the global minimum of the functional F(f). Furthermore, an imaging method and an imaging device using the image reconstruction method are described.

Region-of-interest cone beam computed tomography (ROI CBCT) with a high resolution CMOS detector.

PubMed

Jain, A; Takemoto, H; Silver, M D; Nagesh, S V S; Ionita, C N; Bednarek, D R; Rudin, S

Cone beam computed tomography (CBCT) systems with rotational gantries that have standard flat panel detectors (FPD) are widely used for the 3D rendering of vascular structures using Feldkamp cone beam reconstruction algorithms. One of the inherent limitations of these systems is limited resolution (<3 lp/mm). There are systems available with higher resolution but their small FOV limits them to small animal imaging only. In this work, we report on region-of-interest (ROI) CBCT with a high resolution CMOS detector (75 μm pixels, 600 μm HR-CsI) mounted with motorized detector changer on a commercial FPD-based C-arm angiography gantry (194 μm pixels, 600 μm HL-CsI). A cylindrical CT phantom and neuro stents were imaged with both detectors. For each detector a total of 209 images were acquired in a rotational protocol. The technique parameters chosen for the FPD by the imaging system were used for the CMOS detector. The anti-scatter grid was removed and the incident scatter was kept the same for both detectors with identical collimator settings. The FPD images were reconstructed for the 10 cm x10 cm FOV and the CMOS images were reconstructed for a 3.84 cm × 3.84 cm FOV. Although the reconstructed images from the CMOS detector demonstrated comparable contrast to the FPD images, the reconstructed 3D images of the neuro stent clearly showed that the CMOS detector improved delineation of smaller objects such as the stent struts (~70 μm) compared to the FPD. Further development and the potential for substantial clinical impact are suggested.

The Micro-X Imaging X-Ray Microcalorimeter Sounding Rocket Payload: Final Design and Performance Tests

NASA Astrophysics Data System (ADS)

Rutherford, John; Micro-X Collaboration

2011-09-01

The first operating set of transition edge sensors (TES) microcalorimeters in space will launch on a sounding rocket carrying the Micro-X imaging X-ray telescope in 2012. We present the final instrument flight design, as well as the results from initial performance tests. A spectral resolution of 2 eV is targeted across the science band of 0.3-2.5 keV. The 12x12 spectrometer array contains 128 active pixels on a 600 micron pitch, consisting of Au/Bi absorbers and Mo/Au bilayer TESs with a transition temperature of 100 mK. A SQUID time-division multiplexer will read out the array at 30 kHz, which is limited by the rocket telemetry. The TESs have been engineered with a 2 ms time constant to match the multiplexer. The detector array and two SQUID stages of the TDM readout system are accommodated in a lightweight Mg enclosure, which is mounted to the 50 mK stage of an adiabatic demagnetization refrigerator. A third SQUID amplification stage is located on the 1.6 K liquid He stage of the cryostat. An on-board 55-Fe source will fluoresce a Ca target, providing 3.7 and 4.0 keV calibration lines that will not interfere with the scientifically interesting energy band.

Application of atomic layer deposited microchannel plates to imaging photodetectors with high time resolution

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

Siegmund, O. H. W.; McPhate, J. B.; Tremsin, A. S.

Novel microchannel plates have been constructed using borosilicate glass micro-capillary array substrates with 20 mu m and 10 mu m pores and coated with resistive, and secondary electron emissive, layers by atomic layer deposition. Microchannel plates in 33 mm, 50 mm and 20 cm square formats have been made and tested. Although their amplification, imaging, and timing properties are comparable to standard glass microchannel plates, the background rates and lifetime characteristics are considerably improved. Sealed tube detectors based on the Planacon tube, and a 25 mm cross delay line readout tube with a GaN(Mg) opaque photocathode deposited on borosilicate microchannelmore » plates have been fabricated. Considerable progress has also been made with 20 cm microchannel plates for a 20 cm format sealed tube sensor with strip-line readout that is being developed for Cherenkov light detection.« less

Small field detector correction factors kQclin,Qmsr (fclin,fmsr) for silicon-diode and diamond detectors with circular 6 MV fields derived using both empirical and numerical methods.

PubMed

O'Brien, D J; León-Vintró, L; McClean, B

2016-01-01

The use of radiotherapy fields smaller than 3 cm in diameter has resulted in the need for accurate detector correction factors for small field dosimetry. However, published factors do not always agree and errors introduced by biased reference detectors, inaccurate Monte Carlo models, or experimental errors can be difficult to distinguish. The aim of this study was to provide a robust set of detector-correction factors for a range of detectors using numerical, empirical, and semiempirical techniques under the same conditions and to examine the consistency of these factors between techniques. Empirical detector correction factors were derived based on small field output factor measurements for circular field sizes from 3.1 to 0.3 cm in diameter performed with a 6 MV beam. A PTW 60019 microDiamond detector was used as the reference dosimeter. Numerical detector correction factors for the same fields were derived based on calculations from a geant4 Monte Carlo model of the detectors and the Linac treatment head. Semiempirical detector correction factors were derived from the empirical output factors and the numerical dose-to-water calculations. The PTW 60019 microDiamond was found to over-respond at small field sizes resulting in a bias in the empirical detector correction factors. The over-response was similar in magnitude to that of the unshielded diode. Good agreement was generally found between semiempirical and numerical detector correction factors except for the PTW 60016 Diode P, where the numerical values showed a greater over-response than the semiempirical values by a factor of 3.7% for a 1.1 cm diameter field and higher for smaller fields. Detector correction factors based solely on empirical measurement or numerical calculation are subject to potential bias. A semiempirical approach, combining both empirical and numerical data, provided the most reliable results.

Cadmium Telluride Semiconductor Detector for Improved Spatial and Energy Resolution Radioisotopic Imaging

PubMed Central

Abbaspour, Samira; Mahmoudian, Babak; Islamian, Jalil Pirayesh

2017-01-01

The detector in single-photon emission computed tomography has played a key role in the quality of the images. Over the past few decades, developments in semiconductor detector technology provided an appropriate substitution for scintillation detectors in terms of high sensitivity, better energy resolution, and also high spatial resolution. One of the considered detectors is cadmium telluride (CdTe). The purpose of this paper is to review the CdTe semiconductor detector used in preclinical studies, small organ and small animal imaging, also research in nuclear medicine and other medical imaging modalities by a complete inspect on the material characteristics, irradiation principles, applications, and epitaxial growth method. PMID:28553175

Compressive hyperspectral sensor for LWIR gas detection

NASA Astrophysics Data System (ADS)

Russell, Thomas A.; McMackin, Lenore; Bridge, Bob; Baraniuk, Richard

2012-06-01

Focal plane arrays with associated electronics and cooling are a substantial portion of the cost, complexity, size, weight, and power requirements of Long-Wave IR (LWIR) imagers. Hyperspectral LWIR imagers add significant data volume burden as they collect a high-resolution spectrum at each pixel. We report here on a LWIR Hyperspectral Sensor that applies Compressive Sensing (CS) in order to achieve benefits in these areas. The sensor applies single-pixel detection technology demonstrated by Rice University. The single-pixel approach uses a Digital Micro-mirror Device (DMD) to reflect and multiplex the light from a random assortment of pixels onto the detector. This is repeated for a number of measurements much less than the total number of scene pixels. We have extended this architecture to hyperspectral LWIR sensing by inserting a Fabry-Perot spectrometer in the optical path. This compressive hyperspectral imager collects all three dimensions on a single detection element, greatly reducing the size, weight and power requirements of the system relative to traditional approaches, while also reducing data volume. The CS architecture also supports innovative adaptive approaches to sensing, as the DMD device allows control over the selection of spatial scene pixels to be multiplexed on the detector. We are applying this advantage to the detection of plume gases, by adaptively locating and concentrating target energy. A key challenge in this system is the diffraction loss produce by the DMD in the LWIR. We report the results of testing DMD operation in the LWIR, as well as system spatial and spectral performance.

Method for position emission mammography image reconstruction

DOEpatents

Smith, Mark Frederick

2004-10-12

An image reconstruction method comprising accepting coincidence datat from either a data file or in real time from a pair of detector heads, culling event data that is outside a desired energy range, optionally saving the desired data for each detector position or for each pair of detector pixels on the two detector heads, and then reconstructing the image either by backprojection image reconstruction or by iterative image reconstruction. In the backprojection image reconstruction mode, rays are traced between centers of lines of response (LOR's), counts are then either allocated by nearest pixel interpolation or allocated by an overlap method and then corrected for geometric effects and attenuation and the data file updated. If the iterative image reconstruction option is selected, one implementation is to compute a grid Siddon retracing, and to perform maximum likelihood expectation maiximization (MLEM) computed by either: a) tracing parallel rays between subpixels on opposite detector heads; or b) tracing rays between randomized endpoint locations on opposite detector heads.

High Resolution Energetic X-ray Imager (HREXI)

NASA Astrophysics Data System (ADS)

Grindlay, Jonathan

We propose to design and build the first imaging hard X-ray detector system that incorporates 3D stacking of closely packed detector readouts in finely-spaced imaging arrays with their required data processing and control electronics. In virtually all imaging astronomical detectors, detector readout is done with flex connectors or connections that are not vertical but rather horizontal , requiring loss of focal plane area. For high resolution pixel detectors needed for high speed event-based X-ray imaging, from low energy applications (CMOS) with focusing X-ray telescopes, to hard X-ray applications with pixelated CZT for large area coded aperture telescopes, this new detector development offers great promise. We propose to extend our previous and current APRA supported ProtoEXIST program that has developed the first large area imaging CZT detectors and demonstrated their astrophysical capabilities on two successful balloon flight to a next generation High Resolution Energetic X-ray Imager (HREXI), which would incorporate microvia technology for the first time to connect the readout ASIC on each CZT crystal directly to its control and data processing system. This 3-dimensional stacking of detector and readout/control system means that large area (>2m2) imaging detector planes for a High Resolution Wide-field hard X-ray telescope can be built with initially greatly reduced detector gaps and ultimately with no gaps. This increases detector area, efficiency, and simplicity of detector integration. Thus higher sensitivity wide-field imagers will be possible at lower cost. HREXI will enable a post-Swift NASA mission such as the EREXS concept proposed to PCOS to be conducted as a future MIDEX mission. This mission would conduct a high resolution (<2 arcmin) , broad band (5 200 keV) hard X-ray survey of black holes on all scales with ~10X higher sensitivity than Swift. In the current era of Time Domain Astrophysics, such a survey capability, in conjunction with a nIR telescope in spece, will enable GRBs to be used as probes of the formation of the first stars and structure in the Universe. HREXI on its own, with broad bandwidth and high spectral and spatial resolution, will extend both Galactic surveys for obscured young supernova remnants (44Ti sources) and for transients, black holes and flaring AGN and TDEs well at greatly increased sensitivity and spatial/spectral resolution than has been done with Swift or INTEGRAL. If the HREXI-1 technology is developed in the first year of this proposed effort, it could be used on the upcoming Brazil-US MIRAX telescope on the Lattes satellite, scheduled for a 2018 launch with imaging detector planes to be provided (under contract) by our group. Finally, the 3D stacking technology development proposed here for imaging detector arrays has broad application to Wide Field soft X-ray imaging, to CMB polarization mode (B mode) imaging detectors with very high detector-pixel count, and to Homeland Security.

Direct imaging detectors for electron microscopy

NASA Astrophysics Data System (ADS)

Faruqi, A. R.; McMullan, G.

2018-01-01

Electronic detectors used for imaging in electron microscopy are reviewed in this paper. Much of the detector technology is based on the developments in microelectronics, which have allowed the design of direct detectors with fine pixels, fast readout and which are sufficiently radiation hard for practical use. Detectors included in this review are hybrid pixel detectors, monolithic active pixel sensors based on CMOS technology and pnCCDs, which share one important feature: they are all direct imaging detectors, relying on directly converting energy in a semiconductor. Traditional methods of recording images in the electron microscope such as film and CCDs, are mentioned briefly along with a more detailed description of direct electronic detectors. Many applications benefit from the use of direct electron detectors and a few examples are mentioned in the text. In recent years one of the most dramatic advances in structural biology has been in the deployment of the new backthinned CMOS direct detectors to attain near-atomic resolution molecular structures with electron cryo-microscopy (cryo-EM). The development of direct detectors, along with a number of other parallel advances, has seen a very significant amount of new information being recorded in the images, which was not previously possible-and this forms the main emphasis of the review.

Performance of SEM scintillation detector evaluated by modulation transfer function and detective quantum efficiency function.

PubMed

Bok, Jan; Schauer, Petr

2014-01-01

In the paper, the SEM detector is evaluated by the modulation transfer function (MTF) which expresses the detector's influence on the SEM image contrast. This is a novel approach, since the MTF was used previously to describe only the area imaging detectors, or whole imaging systems. The measurement technique and calculation of the MTF for the SEM detector are presented. In addition, the measurement and calculation of the detective quantum efficiency (DQE) as a function of the spatial frequency for the SEM detector are described. In this technique, the time modulated e-beam is used in order to create well-defined input signal for the detector. The MTF and DQE measurements are demonstrated on the Everhart-Thornley scintillation detector. This detector was alternated using the YAG:Ce, YAP:Ce, and CRY18 single-crystal scintillators. The presented MTF and DQE characteristics show good imaging properties of the detectors with the YAP:Ce or CRY18 scintillator, especially for a specific type of the e-beam scan. The results demonstrate the great benefit of the description of SEM detectors using the MTF and DQE. In addition, point-by-point and continual-sweep e-beam scans in SEM were discussed and their influence on the image quality was revealed using the MTF. © 2013 Wiley Periodicals, Inc.

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

PubMed

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

2016-06-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-02-01

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

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

NASA Astrophysics Data System (ADS)

Darambara, Dimitra G.

2006-12-01

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

235U enrichment determination on UF6 cylinders with CZT detectors

NASA Astrophysics Data System (ADS)

Berndt, Reinhard; Mortreau, Patricia

2018-04-01

Measurements of uranium enrichment in UF6 transit cylinders are an important nuclear safeguards verification task, which is performed using a non-destructive assay method, the traditional enrichment meter, which involves measuring the count rate of the 186 keV gamma ray. This provides a direct measure of the 235U enrichment. Measurements are typically performed using either high-resolution detectors (Germanium) with e-cooling and battery operation, or portable devices equipped with low resolution detectors (NaI). Despite good results being achieved when measuring Low Enriched Uranium in 30B type cylinders and natural uranium in 48Y type containers using both detector systems, there are situations, which preclude the use of one or both of these systems. The focus of this work is to address some of the recognized limitations in relation to the current use of the above detector systems by considering the feasibility of an inspection instrument for 235U enrichment measurements on UF6 cylinders using the compact and light Cadmium Zinc Telluride (CZT) detectors. In the present work, test measurements were carried out, under field conditions and on full-size objects, with different CZT detectors, in particular for situations where existing systems cannot be used e.g. for stacks of 48Y type containers with depleted uranium. The main result of this study shows that the CZT detectors, actually a cluster of four μCZT1500 micro spectrometers provide as good results as the germanium detector in the ORTEC Micro-trans SPEC HPGe Portable spectrometer, and most importantly in particular for natural and depleted uranium in 48Y cylinders.

A Vibrating Wire System For Quadrupole Fiducialization

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

Wolf, Zachary

2010-12-13

A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization stepmore » of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire position detectors. The tooling balls on the wire position detectors are finally related to tooling balls on the quadrupole to perform the fiducialization. The total 25 {micro}m fiducialization error must be divided between these three steps. The wire must be positioned onto the quadrupole magnetic axis to within 10 {micro}m, the wire position must be measured relative to tooling balls on the wire position detectors to within 15 {micro}m, and tooling balls on the wire position detectors must be related to tooling balls on the quadrupole to within 10 {micro}m. The techniques used in these three steps will be discussed. The note begins by discussing various quadrupole fiducialization techniques used in the past and discusses why the vibrating wire technique is our method of choice. We then give an overview of the measurement system showing how the vibrating wire is positioned onto the quadrupole axis, how the wire position detectors locate the wire relative to tooling balls without touching the wire, and how the tooling ball positions are all measured. The novel feature of this system is the vibrating wire which we discuss in depth. We analyze the wire dynamics and calculate the expected sensitivity of the system. The note should be an aid in debugging the system by providing calculations to compare measurements to.« less

Measurements of LET distribution and dose equivalent onboard the Space Shuttle IML-2 (STS-65) and S/MM#4 (STS-79).

PubMed

Hayashi, T; Doke, T; Kikuchi, J; Sakaguchi, T; Takeuchi, R; Takashima, T; Kobayashi, M; Terasawa, K; Takahashi, K; Watanabe, A; Kyan, A; Hasebe, N; Kashiwagi, T; Ogura, K; Nagaoka, S; Kato, M; Nakano, T; Takahashi, S; Yamanaka, H; Yamaguchi, K; Badhwar, G D

1997-12-01

Space radiation dosimetry measurements have been made onboard the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2: 28.5 degrees x 300 km: 14.68 days) and the STS-79 in the 4th Shuttle MIR mission (S/MM#4: 51.6 degrees x 300-400km: 10.2 days). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD-I for IML-2 and RRMD-II with improved triggering system for S/MM#4)" utilizing silicon semi-conductor detectors and the other detectors are conventional passive detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. The main contribution to dose equivalent for particles with LET > 5.0 keV/micrometer (IML-2) and LET > 3.5 keV/micrometer (S/MM#4) is seen to be due to galactic cosmic rays (GCRs) and the contribution of the South Atlantic Anomaly (SAA) is less than 5% (IML-2: 28.5 degrees x 300 km) and 15% (S/MM#4: 51.6 degrees x 400 km) in the above RRMD LET detection conditions. For the whole LET range (> 0.2 kev/micrometer) obtained by TLDs and CR-39 in these two typical orbits (a small inclination x low altitude and a large inclination x high altitude), absorbed dose rates range from 94 to 114 microGy/day, dose equivalent rates from 186 to 207 microSv/day and average quality factors from 1.82 to 2.00 depending on the locations and directions of detectors inside the Spacelab at the highly protected IML-2 orbit (28.5 degrees x 300 km), and also, absorbed dose rates range from 290 to 367 microGy/day, dose equivalent rates from 582 to 651 microSv/day and average quality factors from 1.78 to 2.01 depending on the dosimeter packages around the RRMD-II "Detector Unit" at the S/MM#4 orbit (5l.6 degrees x 400km). In general, it is seen that absorbed doses depend on the orbit altitude (SAA trapped particles contribution dominant) and dose equivalents on the orbit inclination (GCR contribution dominant). The LET distributions obtained by two different types of active and passive detectors, RRMDs and CR-39, are in good agreement for LET of 15 - 200 kev/micrometer and difference of these distributions in the regions of LET < 15 kev/micrometer and LET > 200 kev/micrometer can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks and chemical etching conditions.

Measurements of LET distribution and dose equivalent onboard the Space Shuttle IML-2 (STS-65) and S/MM#4 (STS-79)

NASA Technical Reports Server (NTRS)

Hayashi, T.; Doke, T.; Kikuchi, J.; Sakaguchi, T.; Takeuchi, R.; Takashima, T.; Kobayashi, M.; Terasawa, K.; Takahashi, K.; Watanabe, A.;

A novel three-dimensional image reconstruction method for near-field coded aperture single photon emission computerized tomography

PubMed Central

Mu, Zhiping; Hong, Baoming; Li, Shimin; Liu, Yi-Hwa

2009-01-01

Coded aperture imaging for two-dimensional (2D) planar objects has been investigated extensively in the past, whereas little success has been achieved in imaging 3D objects using this technique. In this article, the authors present a novel method of 3D single photon emission computerized tomography (SPECT) reconstruction for near-field coded aperture imaging. Multiangular coded aperture projections are acquired and a stack of 2D images is reconstructed separately from each of the projections. Secondary projections are subsequently generated from the reconstructed image stacks based on the geometry of parallel-hole collimation and the variable magnification of near-field coded aperture imaging. Sinograms of cross-sectional slices of 3D objects are assembled from the secondary projections, and the ordered subset expectation and maximization algorithm is employed to reconstruct the cross-sectional image slices from the sinograms. Experiments were conducted using a customized capillary tube phantom and a micro hot rod phantom. Imaged at approximately 50 cm from the detector, hot rods in the phantom with diameters as small as 2.4 mm could be discerned in the reconstructed SPECT images. These results have demonstrated the feasibility of the authors’ 3D coded aperture image reconstruction algorithm for SPECT, representing an important step in their effort to develop a high sensitivity and high resolution SPECT imaging system. PMID:19544769

High-energy X-ray diffraction using the Pixium 4700 flat-panel detector.

PubMed

Daniels, J E; Drakopoulos, M

2009-07-01

The Pixium 4700 detector represents a significant step forward in detector technology for high-energy X-ray diffraction. The detector design is based on digital flat-panel technology, combining an amorphous Si panel with a CsI scintillator. The detector has a useful pixel array of 1910 x 2480 pixels with a pixel size of 154 microm x 154 microm, and thus it covers an effective area of 294 mm x 379 mm. Designed for medical imaging, the detector has good efficiency at high X-ray energies. Furthermore, it is capable of acquiring sequences of images at 7.5 frames per second in full image mode, and up to 60 frames per second in binned region of interest modes. Here, the basic properties of this detector applied to high-energy X-ray diffraction are presented. Quantitative comparisons with a widespread high-energy detector, the MAR345 image plate scanner, are shown. Other properties of the Pixium 4700 detector, including a narrow point-spread function and distortion-free image, allows for the acquisition of high-quality diffraction data at high X-ray energies. In addition, high frame rates and shutterless operation open new experimental possibilities. Also provided are the necessary data for the correction of images collected using the Pixium 4700 for diffraction purposes.

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

PubMed Central

Giewekemeyer, Klaus; Philipp, Hugh T.; Wilke, Robin N.; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W.; Shanks, Katherine S.; Zozulya, Alexey V.; Salditt, Tim; Gruner, Sol M.; Mancuso, Adrian P.

2014-01-01

Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 108 8-keV photons pixel−1 s−1, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 1010 photons µm−2 s−1 within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while ‘still’ images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described. PMID:25178008

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

PubMed

Giewekemeyer, Klaus; Philipp, Hugh T; Wilke, Robin N; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W; Shanks, Katherine S; Zozulya, Alexey V; Salditt, Tim; Gruner, Sol M; Mancuso, Adrian P

2014-09-01

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

MO-G-17A-01: Innovative High-Performance PET Imaging System for Preclinical Imaging and Translational Researches

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

Sun, X; Lou, K; Rice University, Houston, TX

Purpose: To develop a practical and compact preclinical PET with innovative technologies for substantially improved imaging performance required for the advanced imaging applications. Methods: Several key components of detector, readout electronics and data acquisition have been developed and evaluated for achieving leapfrogged imaging performance over a prototype animal PET we had developed. The new detector module consists of an 8×8 array of 1.5×1.5×30 mm{sup 3} LYSO scintillators with each end coupled to a latest 4×4 array of 3×3 mm{sup 2} Silicon Photomultipliers (with ∼0.2 mm insensitive gap between pixels) through a 2.0 mm thick transparent light spreader. Scintillator surface andmore » reflector/coupling were designed and fabricated to reserve air-gap to achieve higher depth-of-interaction (DOI) resolution and other detector performance. Front-end readout electronics with upgraded 16-ch ASIC was newly developed and tested, so as the compact and high density FPGA based data acquisition and transfer system targeting 10M/s coincidence counting rate with low power consumption. The new detector module performance of energy, timing and DOI resolutions with the data acquisition system were evaluated. Initial Na-22 point source image was acquired with 2 rotating detectors to assess the system imaging capability. Results: No insensitive gaps at the detector edge and thus it is capable for tiling to a large-scale detector panel. All 64 crystals inside the detector were clearly separated from a flood-source image. Measured energy, timing, and DOI resolutions are around 17%, 2.7 ns and 1.96 mm (mean value). Point source image is acquired successfully without detector/electronics calibration and data correction. Conclusion: Newly developed advanced detector and readout electronics will be enable achieving targeted scalable and compact PET system in stationary configuration with >15% sensitivity, ∼1.3 mm uniform imaging resolution, and fast acquisition counting rate capability for substantially improved imaging and quantification performance for small animal imaging and image-guided radiotherapy applications. This work was supported by a research award RP120326 from Cancer Prevention and Research Institute of Texas.« less

Study of a new design of p-N semiconductor detector array for nuclear medicine imaging by monte carlo simulation codes.

PubMed

Hajizadeh-Safar, M; Ghorbani, M; Khoshkharam, S; Ashrafi, Z

2014-07-01

Gamma camera is an important apparatus in nuclear medicine imaging. Its detection part is consists of a scintillation detector with a heavy collimator. Substitution of semiconductor detectors instead of scintillator in these cameras has been effectively studied. In this study, it is aimed to introduce a new design of P-N semiconductor detector array for nuclear medicine imaging. A P-N semiconductor detector composed of N-SnO2 :F, and P-NiO:Li, has been introduced through simulating with MCNPX monte carlo codes. Its sensitivity with different factors such as thickness, dimension, and direction of emission photons were investigated. It is then used to configure a new design of an array in one-dimension and study its spatial resolution for nuclear medicine imaging. One-dimension array with 39 detectors was simulated to measure a predefined linear distribution of Tc(99_m) activity and its spatial resolution. The activity distribution was calculated from detector responses through mathematical linear optimization using LINPROG code on MATLAB software. Three different configurations of one-dimension detector array, horizontal, vertical one sided, and vertical double-sided were simulated. In all of these configurations, the energy windows of the photopeak were ± 1%. The results show that the detector response increases with an increase of dimension and thickness of the detector with the highest sensitivity for emission photons 15-30° above the surface. Horizontal configuration array of detectors is not suitable for imaging of line activity sources. The measured activity distribution with vertical configuration array, double-side detectors, has no similarity with emission sources and hence is not suitable for imaging purposes. Measured activity distribution using vertical configuration array, single side detectors has a good similarity with sources. Therefore, it could be introduced as a suitable configuration for nuclear medicine imaging. It has been shown that using semiconductor P-N detectors such as P-NiO:Li, N-SnO2 :F for gamma detection could be possibly applicable for design of a one dimension array configuration with suitable spatial resolution of 2.7 mm for nuclear medicine imaging.

Improving depiction of temporal bone anatomy with low-radiation dose CT by an integrated circuit detector in pediatric patients: a preliminary study.

PubMed

He, Jingzhen; Zu, Yuliang; Wang, Qing; Ma, Xiangxing

2014-12-01

The purpose of this study was to determine the performance of low-dose computed tomography (CT) scanning with integrated circuit (IC) detector in defining fine structures of temporal bone in children by comparing with the conventional detector. The study was performed with the approval of our institutional review board and the patients' anonymity was maintained. A total of 86 children<3 years of age underwent imaging of temporal bone with low-dose CT (80 kV/150 mAs) equipped with either IC detector or conventional discrete circuit (DC) detector. The image noise was measured for quantitative analysis. Thirty-five structures of temporal bone were further assessed and rated by 2 radiologists for qualitative analysis. κ Statistics were performed to determine the agreement reached between the 2 radiologists on each image. Mann-Whitney U test was used to determine the difference in image quality between the 2 detector systems. Objective analysis showed that the image noise was significantly lower (P<0.001) with the IC detector than with the DC detector. The κ values for qualitative assessment of the 35 fine anatomical structures revealed high interobserver agreement. The delineation for 30 of the 35 landmarks (86%) with the IC detector was superior to that with the conventional DC detector (P<0.05) although there were no differences in the delineation of the remaining 5 structures (P>0.05). The low-dose CT images acquired with the IC detector provide better depiction of fine osseous structures of temporal bone than that with the conventional DC detector.

New micro-beam beamline at SPring-8, targeting at protein micro-crystallography

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

Hirata, Kunio; Ueno, Go; Nisawa, Atsushi

2010-06-23

A new protein micro-crystallography beamline BL32XU at SPring-8 is under construction and scheduled to start operation in 2010. The beamline is designed to provide the stabilized and brilliant micro-beam to collect high-quality data from micro-crystals. The beamline consists of a hybrid in-vacuum undulator, a liquid-nitrogen cooled double crystal monochromator, and K-B focusing mirrors with large magnification factor. Development of data acquisition system and end station consists of high-precision diffractometer, high-efficiency area detector, sample auto-changer etc. are also in progress.

Ageing Studies on the First Resistive-MicroMeGaS Quadruplet at GIF++ Preliminary Results

NASA Astrophysics Data System (ADS)

Alvarez Gonzalez, B.; Bianco, M.; Farina, E.; Iengo, P.; Kuger, F.; Lin, T.; Longo, L.; Sekhniaidze, G.; Sidiropoulou, O.; Schott, M.; Valderanis, C.; Wotschack, J.

2018-02-01

A resistive-MicroMeGaS quadruplet built at CERN has been installed at the new CERN Gamma Irradiation Facility (GIF++) with the aim of carrying out a long-term ageing study. Two smaller resistive bulk-MicroMeGaS produced at the CERN PCB workshop have also been installed at GIF++ in order to provide a comparison of the ageing behavior with the MicroMeGaS quadruplet. We give an overview of the ongoing tests at GIF++ in terms of particle rate, integrated charge and spatial resolution of the MicroMeGaS detectors.

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.

Development of a Coded Aperture X-Ray Backscatter Imager for Explosive Device Detection

NASA Astrophysics Data System (ADS)

Faust, Anthony A.; Rothschild, Richard E.; Leblanc, Philippe; McFee, John Elton

2009-02-01

Defence R&D Canada has an active research and development program on detection of explosive devices using nuclear methods. One system under development is a coded aperture-based X-ray backscatter imaging detector designed to provide sufficient speed, contrast and spatial resolution to detect antipersonnel landmines and improvised explosive devices. The successful development of a hand-held imaging detector requires, among other things, a light-weight, ruggedized detector with low power requirements, supplying high spatial resolution. The University of California, San Diego-designed HEXIS detector provides a modern, large area, high-temperature CZT imaging surface, robustly packaged in a light-weight housing with sound mechanical properties. Based on the potential for the HEXIS detector to be incorporated as the detection element of a hand-held imaging detector, the authors initiated a collaborative effort to demonstrate the capability of a coded aperture-based X-ray backscatter imaging detector. This paper will discuss the landmine and IED detection problem and review the coded aperture technique. Results from initial proof-of-principle experiments will then be reported.

Integrated circuit detector technology in abdominal CT: added value in obese patients.

PubMed

Morsbach, Fabian; Bickelhaupt, Sebastian; Rätzer, Susan; Schmidt, Bernhard; Alkadhi, Hatem

2014-02-01

The purpose of this article was to assess the effect of an integrated circuit (IC) detector for abdominal CT on image quality. In the first study part, an abdominal phantom was scanned with various extension rings using a CT scanner equipped with a conventional discrete circuit (DC) detector and on the same scanner with an IC detector (120 kVp, 150 effective mAs, and 75 effective mAs). In the second study part, 20 patients were included who underwent abdominal CT both with the IC detector and previously at similar protocol parameters (120 kVp tube current-time product and 150 reference mAs using automated tube current modulation) with the DC detector. Images were reconstructed with filtered back projection. Image quality in the phantom was higher for images acquired with the IC compared with the DC detector. There was a gradually increasing noise reduction with increasing phantom sizes, with the highest (37% in the largest phantom) at 75 effective mAs (p < 0.001). In patients, noise was overall significantly (p = 0.025) reduced by 6.4% using the IC detector. Similar to the phantom, there was a gradual increase in noise reduction to 7.9% in patients with a body mass index of 25 kg/m(2) or lower (p = 0.008). Significant correlation was found in patients between noise and abdominal diameter in DC detector images (r = 0.604, p = 0.005), whereas no such correlation was found for the IC detector (r = 0.427, p = 0.060). Use of an IC detector in abdominal CT improves image quality and reduces image noise, particularly in overweight and obese patients. This noise reduction has the potential for dose reduction in abdominal CT.

Scintillator-fiber charged-particle track-imaging detector

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

Line trace micro-opto-electro-device

NASA Astrophysics Data System (ADS)

Yi, Deer; Lu, Si; Yan, Yingbai; Pang, Lin; Jin, Guofan

2001-05-01

Since micro robot has merits on small size and flexible movements, it could be used under many situations. A lot of novel designs of micro-robot have been developed recently. However, as miniaturizing the size of the micro-robot, the number of its sensor gets restricted. Then the information from the detectors becomes lack. This makes the micro robot difficult to acquire its status. A micro robot tracing a line has been designed in our lab. With the help of optoelectronic detection and logical algorithm, the micro robot could follow a black line printed on the white ground exactly. The micro robot's intelligence is realized through the program in its microprocessor. The technical details of the micro robot are as follows: dimensions: 30mm*25mm*35**; velocity: 60mm/s.

Design and simulation of a planar micro-optic free-space receiver

NASA Astrophysics Data System (ADS)

Nadler, Brett R.; Hallas, Justin M.; Karp, Jason H.; Ford, Joseph E.

2017-11-01

We propose a compact directional optical receiver for free-space communications, where a microlens array and micro-optic structures selectively couple light from a narrow incidence angle into a thin slab waveguide and then to an edge-mounted detector. A small lateral translation of the lenslet array controls the coupled input angle, enabling the receiver to select the transmitter source direction. We present the optical design and simulation of a 10mm x 10mm aperture receiver using a 30μm thick silicon waveguide able to couple up to 2.5Gbps modulated input to a 10mm x 30μm wide detector.

MCNP6 simulated performance of Micro-Pocket Fission Detectors (MPFDs) in the Transient REActor Test (TREAT) Facility

DOE PAGES

Reichenberger, Michael A.; Patel, Vishal K.; Roberts, Jeremy A.; ...

2017-03-03

Here, Micro-Pocket Fission Detectors (MPFDs) are under development for in-core neutron flux measurements at the Transient REActor Test facility (TREAT) and in other experiments at Idaho National Laboratory (INL). The sensitivity of MPFDs to the energy dependent neutron flux at TREAT has been determined for 0.0300-μm thick active material coatings of 242Pu, 232Th, natural uranium, and 93% enriched 235U. Self-shielding effects in the active material of the MPFD was also confirmed to be negligible. Finally, fission fragment energy deposition was found to be in conformance with previously reported results.

Multi-class geospatial object detection and geographic image classification based on collection of part detectors

NASA Astrophysics Data System (ADS)

Cheng, Gong; Han, Junwei; Zhou, Peicheng; Guo, Lei

2014-12-01

The rapid development of remote sensing technology has facilitated us the acquisition of remote sensing images with higher and higher spatial resolution, but how to automatically understand the image contents is still a big challenge. In this paper, we develop a practical and rotation-invariant framework for multi-class geospatial object detection and geographic image classification based on collection of part detectors (COPD). The COPD is composed of a set of representative and discriminative part detectors, where each part detector is a linear support vector machine (SVM) classifier used for the detection of objects or recurring spatial patterns within a certain range of orientation. Specifically, when performing multi-class geospatial object detection, we learn a set of seed-based part detectors where each part detector corresponds to a particular viewpoint of an object class, so the collection of them provides a solution for rotation-invariant detection of multi-class objects. When performing geographic image classification, we utilize a large number of pre-trained part detectors to discovery distinctive visual parts from images and use them as attributes to represent the images. Comprehensive evaluations on two remote sensing image databases and comparisons with some state-of-the-art approaches demonstrate the effectiveness and superiority of the developed framework.

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.

Detection systems for mass spectrometry imaging: a perspective on novel developments with a focus on active pixel detectors.

PubMed

Jungmann, Julia H; Heeren, Ron M A

2013-01-15

Instrumental developments for imaging and individual particle detection for biomolecular mass spectrometry (imaging) and fundamental atomic and molecular physics studies are reviewed. Ion-counting detectors, array detection systems and high mass detectors for mass spectrometry (imaging) are treated. State-of-the-art detection systems for multi-dimensional ion, electron and photon detection are highlighted. Their application and performance in three different imaging modes--integrated, selected and spectral image detection--are described. Electro-optical and microchannel-plate-based systems are contrasted. The analytical capabilities of solid-state pixel detectors--both charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS) chips--are introduced. The Medipix/Timepix detector family is described as an example of a CMOS hybrid active pixel sensor. Alternative imaging methods for particle detection and their potential for future applications are investigated. Copyright © 2012 John Wiley & Sons, Ltd.

Physics of cardiac imaging with multiple-row detector CT.

PubMed

Mahesh, Mahadevappa; Cody, Dianna D

2007-01-01

Cardiac imaging with multiple-row detector computed tomography (CT) has become possible due to rapid advances in CT technologies. Images with high temporal and spatial resolution can be obtained with multiple-row detector CT scanners; however, the radiation dose associated with cardiac imaging is high. Understanding the physics of cardiac imaging with multiple-row detector CT scanners allows optimization of cardiac CT protocols in terms of image quality and radiation dose. Knowledge of the trade-offs between various scan parameters that affect image quality--such as temporal resolution, spatial resolution, and pitch--is the key to optimized cardiac CT protocols, which can minimize the radiation risks associated with these studies. Factors affecting temporal resolution include gantry rotation time, acquisition mode, and reconstruction method; factors affecting spatial resolution include detector size and reconstruction interval. Cardiac CT has the potential to become a reliable tool for noninvasive diagnosis and prevention of cardiac and coronary artery disease. (c) RSNA, 2007.

Stacked Metal Silicide/Silicon Far-Infrared Detectors

NASA Technical Reports Server (NTRS)

Maserjian, Joseph

1988-01-01

Selective doping of silicon in proposed metal silicide/silicon Schottky-barrier infrared photodetector increases maximum detectable wavelength. Stacking layers to form multiple Schottky barriers increases quantum efficiency of detector. Detectors of new type enhance capabilities of far-infrared imaging arrays. Grows by molecular-beam epitaxy on silicon waferscontaining very-large-scale integrated circuits. Imaging arrays of detectors made in monolithic units with image-preprocessing circuitry.

Dual-energy micro-CT imaging of pulmonary airway obstruction: correlation with micro-SPECT

NASA Astrophysics Data System (ADS)

Badea, C. T.; Befera, N.; Clark, D.; Qi, Y.; Johnson, G. A.

2014-03-01

To match recent clinical dual energy (DE) CT studies focusing on the lung, similar developments for DE micro-CT of the rodent lung are required. Our group has been actively engaged in designing pulmonary gating techniques for micro- CT, and has also introduced the first DE micro-CT imaging method of the rodent lung. The aim of this study was to assess the feasibility of DE micro-CT imaging for the evaluation of airway obstruction in mice, and to compare the method with micro single photon emission computed tomography (micro-SPECT) using technetium-99m labeled macroaggregated albumin (99mTc-MAA). The results suggest that the induced pulmonary airway obstruction causes either atelectasis, or air-trapping similar to asthma or chronic bronchitis. Atelectasis could only be detected at early time points in DE micro-CT images, and is associated with a large increase in blood fraction and decrease in air fraction. Air trapping had an opposite effect with larger air fraction and decreased blood fraction shown by DE micro-CT. The decrease in perfusion to the hypoventilated lung (hypoxic vasoconstriction) is also seen in micro-SPECT. The proposed DE micro-CT technique for imaging localized airway obstruction performed well in our evaluation, and provides a higher resolution compared to micro-SPECT. Both DE micro-CT and micro-SPECT provide critical, quantitative lung biomarkers for image-based anatomical and functional information in the small animal. The methods are readily linked to clinical methods allowing direct comparison of preclinical and clinical results.

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Accurate and efficient modeling of the detector response in small animal multi-head PET systems.

PubMed

Cecchetti, Matteo; Moehrs, Sascha; Belcari, Nicola; Del Guerra, Alberto

2013-10-07

In fully three-dimensional PET imaging, iterative image reconstruction techniques usually outperform analytical algorithms in terms of image quality provided that an appropriate system model is used. In this study we concentrate on the calculation of an accurate system model for the YAP-(S)PET II small animal scanner, with the aim to obtain fully resolution- and contrast-recovered images at low levels of image roughness. For this purpose we calculate the system model by decomposing it into a product of five matrices: (1) a detector response component obtained via Monte Carlo simulations, (2) a geometric component which describes the scanner geometry and which is calculated via a multi-ray method, (3) a detector normalization component derived from the acquisition of a planar source, (4) a photon attenuation component calculated from x-ray computed tomography data, and finally, (5) a positron range component is formally included. This system model factorization allows the optimization of each component in terms of computation time, storage requirements and accuracy. The main contribution of this work is a new, efficient way to calculate the detector response component for rotating, planar detectors, that consists of a GEANT4 based simulation of a subset of lines of flight (LOFs) for a single detector head whereas the missing LOFs are obtained by using intrinsic detector symmetries. Additionally, we introduce and analyze a probability threshold for matrix elements of the detector component to optimize the trade-off between the matrix size in terms of non-zero elements and the resulting quality of the reconstructed images. In order to evaluate our proposed system model we reconstructed various images of objects, acquired according to the NEMA NU 4-2008 standard, and we compared them to the images reconstructed with two other system models: a model that does not include any detector response component and a model that approximates analytically the depth of interaction as detector response component. The comparisons confirm previous research results, showing that the usage of an accurate system model with a realistic detector response leads to reconstructed images with better resolution and contrast recovery at low levels of image roughness.

Accurate and efficient modeling of the detector response in small animal multi-head PET systems

NASA Astrophysics Data System (ADS)

Cecchetti, Matteo; Moehrs, Sascha; Belcari, Nicola; Del Guerra, Alberto

2013-10-01

In fully three-dimensional PET imaging, iterative image reconstruction techniques usually outperform analytical algorithms in terms of image quality provided that an appropriate system model is used. In this study we concentrate on the calculation of an accurate system model for the YAP-(S)PET II small animal scanner, with the aim to obtain fully resolution- and contrast-recovered images at low levels of image roughness. For this purpose we calculate the system model by decomposing it into a product of five matrices: (1) a detector response component obtained via Monte Carlo simulations, (2) a geometric component which describes the scanner geometry and which is calculated via a multi-ray method, (3) a detector normalization component derived from the acquisition of a planar source, (4) a photon attenuation component calculated from x-ray computed tomography data, and finally, (5) a positron range component is formally included. This system model factorization allows the optimization of each component in terms of computation time, storage requirements and accuracy. The main contribution of this work is a new, efficient way to calculate the detector response component for rotating, planar detectors, that consists of a GEANT4 based simulation of a subset of lines of flight (LOFs) for a single detector head whereas the missing LOFs are obtained by using intrinsic detector symmetries. Additionally, we introduce and analyze a probability threshold for matrix elements of the detector component to optimize the trade-off between the matrix size in terms of non-zero elements and the resulting quality of the reconstructed images. In order to evaluate our proposed system model we reconstructed various images of objects, acquired according to the NEMA NU 4-2008 standard, and we compared them to the images reconstructed with two other system models: a model that does not include any detector response component and a model that approximates analytically the depth of interaction as detector response component. The comparisons confirm previous research results, showing that the usage of an accurate system model with a realistic detector response leads to reconstructed images with better resolution and contrast recovery at low levels of image roughness.

The Silicon Tracking System of the CBM experiment at FAIR

NASA Astrophysics Data System (ADS)

Teklishyn, Maksym

2018-03-01

The Silicon Tracking System (STS) is the central detector in the Compressed Baryonic Matter (CBM) experiment at FAIR. Operating in the 1Tm dipole magnetic field, the STS will enable pile-up free detection and momentum measurement of the charged particles originating from beam-target nuclear interactions at rates up to 10 MHz. The STS consists of 8 tracking stations based on double-sided silicon micro-strip sensors equipped with fast, self-triggering read-out electronics. With about two million read-out channels, the STS will deliver a high-rate stream of time-stamped data that is transferred to a computing farm for on-line event determination and analysis. The functional building block is a detector module consisting of a sensor, micro-cables and two front-end electronics boards. In this contribution, the development status of the STS components and the system integration is discussed and an outlook on the detector construction is given.

The prototype of the Micro Vertex Detector of the CBM Experiment

NASA Astrophysics Data System (ADS)

Koziel, Michal; Amar-Youcef, Samir; Bialas, Norbert; Deveaux, Michael; Fröhlich, Ingo; Li, Qiyan; Michel, Jan; Milanović, Borislav; Müntz, Christian; Neumann, Bertram; Schrader, Christoph; Stroth, Joachim; Tischler, Tobias; Weirich, Roland; Wiebusch, Michael

2013-12-01

The Compressed Baryonic Matter (CBM) Experiment is one of the core experiments of the future FAIR facility at Darmstadt, Germany. This fixed-target experiment will explore the phase diagram of strongly interacting matter in the regime of highest net baryon densities with numerous probes, among them open charm. Reconstructing those short lived particles requires a vacuum compatible Micro Vertex Detector (MVD) with unprecedented properties. Its sensor technology has to feature a spatial resolution of <5 μm, a non-ionizing radiation tolerance of >1013 neq/cm2, an ionizing radiation tolerance of >3 Mrad and a time resolution of a few 10 μs. The MVD-prototype project aimed to study the integration the CMOS Monolithic Active Pixel Sensors foreseen for the MVD into an ultra light (0.3% X0) and a vacuum compatible detector system based on a cooling support made of CVD-diamond.

Performance of μ-RWELL detector vs resistivity of the resistive stage

NASA Astrophysics Data System (ADS)

Bencivenni, G.; De Oliveira, R.; Felici, G.; Gatta, M.; Morello, G.; Ochi, A.; Lener, M. Poli; Tskhadadze, E.

2018-04-01

The μ-RWELL is a compact spark-protected single amplification stage Micro-Pattern-Gaseous-Detector (MPGD). The detector amplification stage is realized with a polyimide structure, micro-patterned with a dense matrix of blind-holes, integrated into the readout structure. The anode is formed by a thin Diamond Like Carbon (DLC) resistive layer separated by an insulating glue layer from the readout strips. The introduction of the resistive layer strongly suppressing the transition from streamer to spark gives the possibility to achieve large gains (> 104), without significantly affecting the capability to be efficiently operated in high particle fluxes. In this work we present the results of a systematic study of the μ-RWELL performance as a function of the DLC resistivity. The tests have been performed either with collimated 5.9 keV X-rays or with pion and muon beams at the SPS Secondary Beamline H4 and H8 at CERN.

Peripheral Quantitative CT (pQCT) Using a Dedicated Extremity Cone-Beam CT Scanner

PubMed Central

Muhit, A. A.; Arora, S.; Ogawa, M.; Ding, Y.; Zbijewski, W.; Stayman, J. W.; Thawait, G.; Packard, N.; Senn, R.; Yang, D.; Yorkston, J.; Bingham, C.O.; Means, K.; Carrino, J. A.; Siewerdsen, J. H.

2014-01-01

Purpose We describe the initial assessment of the peripheral quantitative CT (pQCT) imaging capabilities of a cone-beam CT (CBCT) scanner dedicated to musculoskeletal extremity imaging. The aim is to accurately measure and quantify bone and joint morphology using information automatically acquired with each CBCT scan, thereby reducing the need for a separate pQCT exam. Methods A prototype CBCT scanner providing isotropic, sub-millimeter spatial resolution and soft-tissue contrast resolution comparable or superior to standard multi-detector CT (MDCT) has been developed for extremity imaging, including the capability for weight-bearing exams and multi-mode (radiography, fluoroscopy, and volumetric) imaging. Assessment of pQCT performance included measurement of bone mineral density (BMD), morphometric parameters of subchondral bone architecture, and joint space analysis. Measurements employed phantoms, cadavers, and patients from an ongoing pilot study imaged with the CBCT prototype (at various acquisition, calibration, and reconstruction techniques) in comparison to MDCT (using pQCT protocols for analysis of BMD) and micro-CT (for analysis of subchondral morphometry). Results The CBCT extremity scanner yielded BMD measurement within ±2–3% error in both phantom studies and cadaver extremity specimens. Subchondral bone architecture (bone volume fraction, trabecular thickness, degree of anisotropy, and structure model index) exhibited good correlation with gold standard micro-CT (error ~5%), surpassing the conventional limitations of spatial resolution in clinical MDCT scanners. Joint space analysis demonstrated the potential for sensitive 3D joint space mapping beyond that of qualitative radiographic scores in application to non-weight-bearing versus weight-bearing lower extremities and assessment of phalangeal joint space integrity in the upper extremities. Conclusion The CBCT extremity scanner demonstrated promising initial results in accurate pQCT analysis from images acquired with each CBCT scan. Future studies will include improved x-ray scatter correction and image reconstruction techniques to further improve accuracy and to correlate pQCT metrics with known pathology. PMID:25076823

Development of a software based automatic exposure control system for use in image guided radiation therapy

NASA Astrophysics Data System (ADS)

Morton, Daniel R.

Modern image guided radiation therapy involves the use of an isocentrically mounted imaging system to take radiographs of a patient's position before the start of each treatment. Image guidance helps to minimize errors associated with a patients setup, but the radiation dose received by patients from imaging must be managed to ensure no additional risks. The Varian On-Board Imager (OBI) (Varian Medical Systems, Inc., Palo Alto, CA) does not have an automatic exposure control system and therefore requires exposure factors to be manually selected. Without patient specific exposure factors, images may become saturated and require multiple unnecessary exposures. A software based automatic exposure control system has been developed to predict optimal, patient specific exposure factors. The OBI system was modelled in terms of the x-ray tube output and detector response in order to calculate the level of detector saturation for any exposure situation. Digitally reconstructed radiographs are produced via ray-tracing through the patients' volumetric datasets that are acquired for treatment planning. The ray-trace determines the attenuation of the patient and subsequent x-ray spectra incident on the imaging detector. The resulting spectra are used in the detector response model to determine the exposure levels required to minimize detector saturation. Images calculated for various phantoms showed good agreement with the images that were acquired on the OBI. Overall, regions of detector saturation were accurately predicted and the detector response for non-saturated regions in images of an anthropomorphic phantom were calculated to generally be within 5 to 10 % of the measured values. Calculations were performed on patient data and found similar results as the phantom images, with the calculated images being able to determine detector saturation with close agreement to images that were acquired during treatment. Overall, it was shown that the system model and calculation method could potentially be used to predict patients' exposure factors before their treatment begins, thus preventing the need for multiple exposures.

A Thermal Imaging Instrument with Uncooled Detectors

NASA Technical Reports Server (NTRS)

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

2018-01-01

In this work, we performed an instrument concept study for sustainable thermal imaging over land with uncooled detectors. We evaluated two different uncooled detector technologies uncooled microbolometers and thermopiles. We have also evaluated materials for use in in a uncooled thermopile detector concept.

Vibration Isolation System for Cryocoolers of Soft X-Ray Spectrometer (SXS) Onboard ASTRO-H (Hitomi)

NASA Technical Reports Server (NTRS)

Takei, Yoh; Yasuda, Susumu; Ishimura, Kosei; Iwata, Naoko; Okamoto, Atsushi; Sato, Yoichi; Ogawa, Mina; Sawada, Makoto; Kawano, Taro; Obara, Shingo;

Experimental study on the 3D image reconstruction in a truncated Archimedean-like spiral geometry with a long-rectangular detector and its image characteristics

NASA Astrophysics Data System (ADS)

Hong, Daeki; Cho, Heemoon; Cho, Hyosung; Choi, Sungil; Je, Uikyu; Park, Yeonok; Park, Chulkyu; Lim, Hyunwoo; Park, Soyoung; Woo, Taeho

2015-11-01

In this work, we performed a feasibility study on the three-dimensional (3D) image reconstruction in a truncated Archimedean-like spiral geometry with a long-rectangular detector for application to high-accurate, cost-effective dental x-ray imaging. Here an x-ray tube and a detector rotate together around the rotational axis several times and, concurrently, the detector moves horizontally in the detector coordinate at a constant speed to cover the whole imaging volume during the projection data acquisition. We established a table-top setup which mainly consists of an x-ray tube (60 kVp, 5 mA), a narrow CMOS-type detector (198-μm pixel resolution, 184 (W)×1176 (H) pixel dimension), and a rotational stage for sample mounting and performed a systematic experiment to demonstrate the viability of the proposed approach to volumetric dental imaging. For the image reconstruction, we employed a compressed-sensing (CS)-based algorithm, rather than a common filtered-backprojection (FBP) one, for more accurate reconstruction. We successfully reconstructed 3D images of considerably high quality and investigated the image characteristics in terms of the image value profile, the contrast-to-noise ratio (CNR), and the spatial resolution.

Dual Functional Roles of Molecular Beacon as a MicroRNA Detector and Inhibitor.

PubMed

Li, Wai Ming; Chan, Ching-Man; Miller, Andrew L; Lee, Chow H

2017-03-03

MicroRNAs are essential in many cellular processes. The ability to detect microRNAs is important for understanding its function and biogenesis. This study is aimed at using a molecular beacon to detect miR-430 in developing zebrafish embryos as a proof of principle. miR-430 is crucial for the clearance of maternal mRNA during maternal zygotic transition in embryonic development. Despite its known function, the temporal and spatial expression of miR-430 remains unclear. We used various imaging techniques, including laser scanning confocal microscopy, spinning disk, and lightsheet microscopy, to study the localization of miR-430 and any developmental defects possibly caused by the molecular beacon. Our results show that miR-430 is expressed early in development and is localized in distinct cytoplasmic granules where its target mRNA can be detected. We also show that the designed molecular beacon can inhibit the function of miR-430 and cause developmental defect in the brain, notochord, heart, and kidney, depending on the delivery site within the embryo, suggesting that miR-430 plays a diverse role in embryonic morphogenesis. When compared with morpholino, molecular beacon is 2 orders of magnitude more potent in inhibiting miR-430. Thus, our results reveal that in addition to being used as a valuable tool for the detection of microRNAs in vivo , molecular beacons can also be employed to inhibit microRNAs in a specific manner. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Detector motion method to increase spatial resolution in photon-counting detectors

NASA Astrophysics Data System (ADS)

Lee, Daehee; Park, Kyeongjin; Lim, Kyung Taek; Cho, Gyuseong

2017-03-01

Medical imaging requires high spatial resolution of an image to identify fine lesions. Photon-counting detectors in medical imaging have recently been rapidly replacing energy-integrating detectors due to the former`s high spatial resolution, high efficiency and low noise. Spatial resolution in a photon counting image is determined by the pixel size. Therefore, the smaller the pixel size, the higher the spatial resolution that can be obtained in an image. However, detector redesigning is required to reduce pixel size, and an expensive fine process is required to integrate a signal processing unit with reduced pixel size. Furthermore, as the pixel size decreases, charge sharing severely deteriorates spatial resolution. To increase spatial resolution, we propose a detector motion method using a large pixel detector that is less affected by charge sharing. To verify the proposed method, we utilized a UNO-XRI photon-counting detector (1-mm CdTe, Timepix chip) at the maximum X-ray tube voltage of 80 kVp. A similar spatial resolution of a 55- μm-pixel image was achieved by application of the proposed method to a 110- μm-pixel detector with a higher signal-to-noise ratio. The proposed method could be a way to increase spatial resolution without a pixel redesign when pixels severely suffer from charge sharing as pixel size is reduced.

High voltage testing for the Majorana Demonstrator

DOE PAGES

Abgrall, N.; Arnquist, I. J.; Avignone, III, F. T.; ...

2016-04-04

The Majorana Collaboration is constructing the Majorana Demonstrator, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in 76Ge. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of the Majorana Demonstrator. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of themore » high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the Majorana Demonstrator was characterized and the micro-discharge effects during the Majorana Demonstrator commissioning phase were studied. Furthermore, a stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge.« less

High voltage testing for the Majorana Demonstrator

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

Abgrall, N.; Arnquist, Isaac J.; Avignone, F. T.

2016-07-01

The Majorana Collaboration is constructing theMajorana Demonstrator, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in 76Ge. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of theMajorana Demonstrator. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of the high-voltage path,more » including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the Majorana Demonstrator was characterized and the micro-discharge effects during theMajorana Demonstrator commissioning phase were studied. A stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge.« less

Using the Wiener estimator to determine optimal imaging parameters in a synthetic-collimator SPECT system used for small animal imaging

NASA Astrophysics Data System (ADS)

Lin, Alexander; Johnson, Lindsay C.; Shokouhi, Sepideh; Peterson, Todd E.; Kupinski, Matthew A.

2015-03-01

In synthetic-collimator SPECT imaging, two detectors are placed at different distances behind a multi-pinhole aperture. This configuration allows for image detection at different magnifications and photon energies, resulting in higher overall sensitivity while maintaining high resolution. Image multiplexing the undesired overlapping between images due to photon origin uncertainty may occur in both detector planes and is often present in the second detector plane due to greater magnification. However, artifact-free image reconstruction is possible by combining data from both the front detector (little to no multiplexing) and the back detector (noticeable multiplexing). When the two detectors are used in tandem, spatial resolution is increased, allowing for a higher sensitivity-to-detector-area ratio. Due to variability in detector distances and pinhole spacings found in synthetic-collimator SPECT systems, a large parameter space must be examined to determine optimal imaging configurations. We chose to assess image quality based on the task of estimating activity in various regions of a mouse brain. Phantom objects were simulated using mouse brain data from the Magnetic Resonance Microimaging Neurological Atlas (MRM NeAt) and projected at different angles through models of a synthetic-collimator SPECT system, which was developed by collaborators at Vanderbilt University. Uptake in the different brain regions was modeled as being normally distributed about predetermined means and variances. We computed the performance of the Wiener estimator for the task of estimating activity in different regions of the mouse brain. Our results demonstrate the utility of the method for optimizing synthetic-collimator system design.

PREFACE: 22nd International Congress on X-Ray Optics and Microanalysis

NASA Astrophysics Data System (ADS)

Falkenberg, Gerald; Schroer, Christian G.

2014-04-01

ICXOM22 The 22nd edition of the International Congress on X-ray Optics and Microanalysis (ICXOM 22) was held from 2-6 September 2013, in Hamburg, Germany. The congress was organized by scientists from DESY in collaboration with TU Dresden and Helmholtz-Zentrum Geesthacht, who also formed the scientific advisory board. The congress was hosted in the historical lecture hall building of the University of Hamburg located in the city center. ICXOM22 was attended by about 210 registered participants, including 67 students, and was open for listeners. The attendance was split between 26 countries (Germany 120, rest of Europe 57, America 20, Asia 8, Australia 6). The ICXOM series is a forum for the discussion of new developments in instrumentation, methods and applications in the fields of micro- and nano-analysis by means of X-ray beams. Following the trend of the last 10 years, the conference focusses more and more on synchrotron radiation rather than X-ray laboratory sources. Besides micro-beam X-ray fluorescence and absorption spectroscopy, different methods based on diffraction and full-field imaging were covered. Newly introduced to the ICXOM series was scanning coherent X-ray diffraction imaging, which was shown to evolve into a mature method for the imaging of nanostructures, defects and strain fields. New developments on fast X-ray detectors were discussed (Lambda, Maia) and advances in X-ray optics — like the generation of a sub 5nm point focus by Multilayer Zone plates — were presented. Talks on micro- and nano-analysis applications were distributed in special sessions on bio-imaging, Earth and environmental sciences, and Cultural heritage. The congress featured nine keynote and ten plenary talks, 56 talks in 14 parallel sessions and about 120 posters in three afternoon sessions. Seventeen commercial exhibitors exposed related X-ray instrumentation products, and two luncheon seminars on detector electronics were given. This allowed us to keep the student fees low and to distribute eight student travel grants. The Wednesday was devoted to an outing to DESY with guided tours to PETRA III and FLASH experiments and to the European XFEL construction site. A lecture was given by Henry Chapman introducing to structural imaging at X-ray free-electron lasers. Talks highlighting the current status and future of nanoanalysis at the leading synchrotron facilities APS (J Maser), ESRF (P Cloetens) and SPRing8 (Ishikawa) were given in the DESY auditorium offering other DESY scientists the opportunity to follow the talks. Participants A higher quality version of this image is available in supplementary data Further information about ICXOM22, including a detailed program and electronic abstract book, can be found on the congress website www.icxom22.de. We thank all the participants of ICXOM22, everybody who helped in the organization and are looking forward to hearing about further progress during ICXOM23, which will be organized by Brookhaven National Laboratory in Uptown, New York. Gerald Falkenberg ICXOM22 conference chair Christian Schroer ICXOM22 co-chair

Non-streaming high-efficiency perforated semiconductor neutron detectors, methods of making same and measuring wand and detector modules utilizing same

DOEpatents

McGregor, Douglas S.; Shultis, John K.; Rice, Blake B.; McNeil, Walter J.; Solomon, Clell J.; Patterson, Eric L.; Bellinger, Steven L.

2010-12-21

Non-streaming high-efficiency perforated semiconductor neutron detectors, method of making same and measuring wands and detector modules utilizing same are disclosed. The detectors have improved mechanical structure, flattened angular detector responses, and reduced leakage current. A plurality of such detectors can be assembled into imaging arrays, and can be used for neutron radiography, remote neutron sensing, cold neutron imaging, SNM monitoring, and various other applications.

Realization of 10 GHz minus 30dB on-chip micro-optical links with Si-Ge RF bi-polar technology

NASA Astrophysics Data System (ADS)

Ogudo, Kingsley A.; Snyman, Lukas W.; Polleux, Jean-Luc; Viana, Carlos; Tegegne, Zerihun

2014-06-01

Si Avalanche based LEDs technology has been developed in the 650 -850nm wavelength regime [1, 2]. Correspondingly, small micro-dimensioned detectors with pW/μm2 sensitivity have been developed for the same wavelength range utilizing Si-Ge detector technology with detection efficiencies of up to 0.85, and with a transition frequencies of up to 80 GHz [3] A series of on-chip optical links of 50 micron length, utilizing 650 - 850 nm propagation wavelength have been designed and realized, utilizing a Si Ge radio frequency bipolar process. Micron dimensioned optical sources, waveguides and detectors were all integrated on the same chip to form a complete optical link on-chip. Avalanche based Si LEDs (Si Av LEDs), Schottky contacting, TEOS densification strategies, silicon nitride based waveguides, and state of the art Si-Ge bipolar detector technologies were used as key design strategies. Best performances show optical coupling from source to detector of up to 10GHz and - 40dBm total optical link budget loss with a potential transition frequency coupling of up to 40GHz utilizing Si Ge based LEDs. The technology is particularly suitable for application as on-chip optical links, optical MEMS and MOEMS, as well as for optical interconnects utilizing low loss, side surface, waveguide- to-optical fiber coupling. Most particularly is one of our designed waveguide which have a good core axis alignment with the optical source and yield 10GHz -30dB on-chip micro-optical links as shown in Fig 9 (c). The technology as developed has been appropriately IP protected.

High-Resolution Detector For X-Ray Diffraction

NASA Technical Reports Server (NTRS)

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

1988-01-01

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

Development and investigation of a magnetic resonance imaging-compatible microlens-based optical detector

NASA Astrophysics Data System (ADS)

Paar, Steffen; Umathum, Reiner; Jiang, Xiaoming; Majer, Charles L.; Peter, Jörg

2015-09-01

A noncontact optical detector for in vivo imaging has been developed that is compatible with magnetic resonance imaging (MRI). The optical detector employs microlens arrays and might be classified as a plenoptic camera. As a resulting of its design, the detector possesses a slim thickness and is self-shielding against radio frequency (RF) pulses. For experimental investigation, a total of six optical detectors were arranged in a cylindrical fashion, with the imaged object positioned in the center of this assembly. A purposely designed RF volume resonator coil has been developed and is incorporated within the optical imaging system. The whole assembly was placed into the bore of a 1.5 T patient-sized MRI scanner. Simple-geometry phantom studies were performed to assess compatibility and performance characteristics regarding both optical and MR imaging systems. A bimodal ex vivo nude mouse measurement was conducted. From the MRI data, the subject surface was extracted. Optical images were projected on this surface by means of an inverse mapping algorithm. Simultaneous measurements did not reveal influences from the magnetic field and RF pulses onto optical detector performance (spatial resolution, sensitivity). No significant influence of the optical imaging system onto MRI performance was detectable.

Development and investigation of a magnetic resonance imaging-compatible microlens-based optical detector.

PubMed

Paar, Steffen; Umathum, Reiner; Jiang, Xiaoming; Majer, Charles L; Peter, Jörg

2015-09-01

A noncontact optical detector for in vivo imaging has been developed that is compatible with magnetic resonance imaging (MRI). The optical detector employs microlens arrays and might be classified as a plenoptic camera. As a resulting of its design, the detector possesses a slim thickness and is self-shielding against radio frequency (RF) pulses. For experimental investigation, a total of six optical detectors were arranged in a cylindrical fashion, with the imaged object positioned in the center of this assembly. A purposely designed RF volume resonator coil has been developed and is incorporated within the optical imaging system. The whole assembly was placed into the bore of a 1.5 T patient-sized MRI scanner. Simple-geometry phantom studies were performed to assess compatibility and performance characteristics regarding both optical and MR imaging systems. A bimodal ex vivo nude mouse measurement was conducted. From the MRI data, the subject surface was extracted. Optical images were projected on this surface by means of an inverse mapping algorithm. Simultaneous measurements did not reveal influences from the magnetic field and RF pulses onto optical detector performance (spatial resolution, sensitivity). No significant influence of the optical imaging system onto MRI performance was detectable.

X-ray imaging detectors for synchrotron and XFEL sources

PubMed Central

Hatsui, Takaki; Graafsma, Heinz

2015-01-01

Current trends for X-ray imaging detectors based on hybrid and monolithic detector technologies are reviewed. Hybrid detectors with photon-counting pixels have proven to be very powerful tools at synchrotrons. Recent developments continue to improve their performance, especially for higher spatial resolution at higher count rates with higher frame rates. Recent developments for X-ray free-electron laser (XFEL) experiments provide high-frame-rate integrating detectors with both high sensitivity and high peak signal. Similar performance improvements are sought in monolithic detectors. The monolithic approach also offers a lower noise floor, which is required for the detection of soft X-ray photons. The link between technology development and detector performance is described briefly in the context of potential future capabilities for X-ray imaging detectors. PMID:25995846

Atise: a miniature Fourier-transform spectro-imaging concept for surveying auroras and airglow monitoring from a 6/12u cubesat

NASA Astrophysics Data System (ADS)

Le Courer, E.; Barthelemy, M.; Vialatte, A.; Prugniaux, M.; Bourdarot, G.; Sequies, T.; Monsinjon, P.; Puget, R.; Guerineau, N.

2017-09-01

The nanosatellite ATISE is a mission dedicated to the observation of the emission spectra of the upper atmosphere (i.e. Airglow and Auroras) mainly related to both the solar UV flux and the precipitation of suprathermal particles coming from the solar wind through the magnetosphere. ATISE will measure specifically the auroral emissions, and the airglow (day- and night) in the spectral range between 380 and 900 nm at altitudes between 100 and 350 km. The exposure time will be 1 second in auroral region and 20 s at low latitude regions. The 5 year expected lifetime of this mission should cover almost a half of solar cycle (2 years nominal). This instrument concept is based on an innovative miniaturized Fourier-transform spectrometer (FTS) allowing simultaneous 1 Rayleigh sensitivity detection along six 1.5°x1° limb lines of sight. This 1-2kg payload instrument is hosted in a 12U cubeSat where 6U are allocated to the payload and 6U to the plateform subsystems. This represents a miniaturisation by a factor of 500 on weight and volume compared to previous Arizona-GLO instrument for equivalent performances in the visible. The instrument is based on microSPOC concept developed by ONERA and IPAG using one Fizeau interferometer per line of sight directly glued on top of the half of a very sensitive CMOS Pyxalis HDPYX detector. Three detectors are necessary with a total electrical consumption compatible with a 6U nanoSat. Each interferometer occupies a 1.4 M pixel part of detector, each is placed on an image of the entrance pupil corresponding to a unique direction of the six lines of sight, this in order to have a uniform illumination permitting good spectral Fourier reconstruction from fringes created between the Fizeau plate and the detector itself. Despite a limited 8x6 cm telescope, this configuration takes advantage of FTS multiplex effect and permits us to maximize the throughput and to integrate very faint emission lines over a wide field of view even if the 1 second integrated signal is comparable to the detector noise.

Statistical relative gain calculation for Landsat 8

NASA Astrophysics Data System (ADS)

Anderson, Cody; Helder, Dennis L.; Jeno, Drake

2017-09-01

The Landsat 8 Operational Land Imager (OLI) is an optical multispectral push-broom sensor with a focal plane consisting of over 7000 detectors per spectral band. Each of the individual imaging detectors contributes one column of pixels to an image. Any difference in the response between neighboring detectors may result in a visible stripe or band in the imagery. An accurate estimate of each detector's relative gain is needed to account for any differences between detector responses. This paper describes a procedure for estimating relative gains which uses normally acquired Earth viewing statistics.

Estimate of the effect of micro-vibration on the performance of the Algerian satellite (Alsat-1B) imager

NASA Astrophysics Data System (ADS)

Serief, Chahira

2017-11-01

Alsat-1B, launched into a 670 km sun-synchronous orbit on board the PSLV launch vehicle from the Sriharikota launch site in India on 26 September 2016, is a medium resolution Earth Observation satellite with a mass of 100 kg. Alsat-1B will be used for agricultural and resource monitoring, disaster management, land use mapping and urban planning. It is based on the SSTL-100 platform, and flies a 24 m multispectral imager and a 12 m panchromatic imager delivering images with a swath width of 140 km. One of the main factors affecting the performance of satellite-borne optical imaging systems is micro-vibration. Micro-vibration is a low level mechanical disturbance inevitably generated from moving parts on a satellite and exceptionally difficult to be controlled by the attitude and orbital control system (AOCS) of a spacecraft. Micro-vibration usually causes problems for optical imaging systems onboard Earth Observation satellites. The major effect of micro-vibration is the excitation of the support structures for the optical elements during imaging operations which can result in severe degradation of image quality by smearing and distortion. Quantitative characterization of image degradation caused by micro-vibration is thus quite useful and important as part of system level analysis which can help preventing micro-vibration influence by proper design and restoring the degraded image. The aim of this work is to provide quantitative estimates of the effect of micro-vibration on the performance of Alsat-1B imager, which may be experienced operationally, in terms of the modulation transfer function (MTF) and based on ground micro-vibration tests results.

Spectral X-Ray Diffraction using a 6 Megapixel Photon Counting Array Detector.

PubMed

Muir, Ryan D; Pogranichniy, Nicholas R; Muir, J Lewis; Sullivan, Shane Z; Battaile, Kevin P; Mulichak, Anne M; Toth, Scott J; Keefe, Lisa J; Simpson, Garth J

2015-03-12

Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

Spectral x-ray diffraction using a 6 megapixel photon counting array detector

NASA Astrophysics Data System (ADS)

Muir, Ryan D.; Pogranichniy, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

2015-03-01

Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

WE-F-16A-04: Micro-Irradiator Treatment Verification with High-Resolution 3D-Printed Rodent-Morphic Dosimeters

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

Bache, S; Belley, M; Benning, R

2014-06-15

Purpose: Pre-clinical micro-radiation therapy studies often utilize very small beams (∼0.5-5mm), and require accurate dose delivery in order to effectively investigate treatment efficacy. Here we present a novel high-resolution absolute 3D dosimetry procedure, capable of ∼100-micron isotopic dosimetry in anatomically accurate rodent-morphic phantoms Methods: Anatomically accurate rat-shaped 3D dosimeters were made using 3D printing techniques from outer body contours and spinal contours outlined on CT. The dosimeters were made from a radiochromic plastic material PRESAGE, and incorporated high-Z PRESASGE inserts mimicking the spine. A simulated 180-degree spinal arc treatment was delivered through a 2 step process: (i) cone-beam-CT image-guided positioningmore » was performed to precisely position the rat-dosimeter for treatment on the XRad225 small animal irradiator, then (ii) treatment was delivered with a simulated spine-treatment with a 180-degree arc with 20mm x 10mm cone at 225 kVp. Dose distribution was determined from the optical density change using a high-resolution in-house optical-CT system. Absolute dosimetry was enabled through calibration against a novel nano-particle scintillation detector positioned in a channel in the center of the distribution. Results: Sufficient contrast between regular PRESAGE (tissue equivalent) and high-Z PRESAGE (spinal insert) was observed to enable highly accurate image-guided alignment and targeting. The PRESAGE was found to have linear optical density (OD) change sensitivity with respect to dose (R{sup 2} = 0.9993). Absolute dose for 360-second irradiation at isocenter was found to be 9.21Gy when measured with OD change, and 9.4Gy with nano-particle detector- an agreement within 2%. The 3D dose distribution was measured at 500-micron resolution Conclusion: This work demonstrates for the first time, the feasibility of accurate absolute 3D dose measurement in anatomically accurate rat phantoms containing variable density PRESAGE material (tissue equivalent and bone equivalent). This method enables precise treatment verification of micro-radiation therapies, and enhances the robustness of tumor radio-response studies. This work was supported by NIH R01CA100835.« less

X-ray tests of a microchannel plate detector and amorphous silicon pixel array readout for neutron radiography

NASA Astrophysics Data System (ADS)

Ambrosi, R. M.; Street, R.; Feller, B.; Fraser, G. W.; Watterson, J. I. W.; Lanza, R. C.; Dowson, J.; Ross, D.; Martindale, A.; Abbey, A. F.; Vernon, D.

2007-03-01

High-performance large area imaging detectors for fast neutrons in the 5-14 MeV energy range do not exist at present. The aim of this project is to combine microchannel plates or MCPs (or similar electron multiplication structures) traditionally used in image intensifiers and X-ray detectors with amorphous silicon (a-Si) pixel arrays to produce a composite converter and intensifier position sensitive imaging system. This detector will provide an order of magnitude improvement in image resolution when compared with current millimetre resolution limits obtained using phosphor or scintillator-based hydrogen rich converters. In this study we present the results of the initial experimental evaluation of the prototype system. This study was carried out using a medical X-ray source for the proof of concept tests, the next phase will involve neutron imaging tests. The hybrid detector described in this study is a unique development and paves the way for large area position sensitive detectors consisting of MCP or microsphere plate detectors and a-Si or polysilicon pixel arrays. Applications include neutron and X-ray imaging for terrestrial applications. The technology could be extended to space instrumentation for X-ray astronomy.

Edge detection and localization with edge pattern analysis and inflection characterization

NASA Astrophysics Data System (ADS)

Jiang, Bo

2012-05-01

In general edges are considered to be abrupt changes or discontinuities in two dimensional image signal intensity distributions. The accuracy of front-end edge detection methods in image processing impacts the eventual success of higher level pattern analysis downstream. To generalize edge detectors designed from a simple ideal step function model to real distortions in natural images, research on one dimensional edge pattern analysis to improve the accuracy of edge detection and localization proposes an edge detection algorithm, which is composed by three basic edge patterns, such as ramp, impulse, and step. After mathematical analysis, general rules for edge representation based upon the classification of edge types into three categories-ramp, impulse, and step (RIS) are developed to reduce detection and localization errors, especially reducing "double edge" effect that is one important drawback to the derivative method. But, when applying one dimensional edge pattern in two dimensional image processing, a new issue is naturally raised that the edge detector should correct marking inflections or junctions of edges. Research on human visual perception of objects and information theory pointed out that a pattern lexicon of "inflection micro-patterns" has larger information than a straight line. Also, research on scene perception gave an idea that contours have larger information are more important factor to determine the success of scene categorization. Therefore, inflections or junctions are extremely useful features, whose accurate description and reconstruction are significant in solving correspondence problems in computer vision. Therefore, aside from adoption of edge pattern analysis, inflection or junction characterization is also utilized to extend traditional derivative edge detection algorithm. Experiments were conducted to test my propositions about edge detection and localization accuracy improvements. The results support the idea that these edge detection method improvements are effective in enhancing the accuracy of edge detection and localization.

Scintillator-fiber charged particle track-imaging detector

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

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

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

[Design of longitudinal auto-tracking of the detector on X-ray in digital radiography].

PubMed

Yu, Xiaomin; Jiang, Tianhao; Liu, Zhihong; Zhao, Xu

2018-04-01

One algorithm is designed to implement longitudinal auto-tracking of the the detector on X-ray in the digital radiography system (DR) with manual collimator. In this study, when the longitudinal length of field of view (LFOV) on the detector is coincided with the longitudinal effective imaging size of the detector, the collimator half open angle ( Ψ ), the maximum centric distance ( e max ) between the center of X-ray field of view and the projection center of the focal spot, and the detector moving distance for auto-traking can be calculated automatically. When LFOV is smaller than the longitudinal effective imaging size of the detector by reducing Ψ , the e max can still be used to calculate the detector moving distance. Using this auto-tracking algorithm in DR with manual collimator, the tested results show that the X-ray projection is totally covered by the effective imaging area of the detector, although the center of the field of view is not aligned with the center of the effective imaging area of the detector. As a simple and low-cost design, the algorithm can be used for longitudinal auto-tracking of the detector on X-ray in the manual collimator DR.

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

PubMed

Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

2014-02-07

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

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

NASA Astrophysics Data System (ADS)

Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

2014-02-01

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

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

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

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

2010-03-15

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

Tunable Fabry-Perot etalon-based long-wavelength infrared imaging spectroradiometer.

PubMed

Marinelli, W J; Gittins, C M; Gelb, A H; Green, B D

1999-04-20

Imaging spectrometry enables passive, stand-off detection and analysis of the chemical composition of gas plumes and surfaces over wide geographic areas. We describe the use of a long-wavelength infrared imaging spectroradiometer, comprised of a low-order tunable Fabry-Perot etalon coupled to a HgCdTe detector array, to perform multispectral detection of chemical vapor plumes. The tunable Fabry-Perot etalon used in this research provides coverage of the 9.5-14-microm spectral region with a resolution of 7-9 cm(-1). The etalon-based imaging system provides the opportunity to image a scene at only those wavelengths needed for chemical species identification and quantification and thereby minimize the data volume necessary for selective species detection. We present initial results using a brassboard imaging system for stand-off detection and quantification of chemical vapor plumes against near-ambient-temperature backgrounds. These data show detection limits of 22 parts per million by volume times meter (ppmv x m) and 0.6 ppmv x m for dimethyl methyphosphonate and SF6, respectively, for a gas/background DeltaT of 6 K. The system noise-equivalent spectral radiance is approximately 2 microW cm(-2) sr(-1) microm(-1). Model calculations are presented comparing the measured sensitivity of the sensor to the anticipated signal levels for two chemical release scenarios.

Imaging responses of on-site CsI and Gd2O2S flat-panel detectors: Dependence on the tube voltage

NASA Astrophysics Data System (ADS)

Jeon, Hosang; Chung, Myung Jin; Youn, Seungman; Nam, Jiho; Lee, Jayoung; Park, Dahl; Kim, Wontaek; Ki, Yongkan; Kim, Ho Kyung

2015-07-01

One of the emerging issues in radiography is low-dose imaging to minimize patient's exposure. The scintillating materials employed in most indirect flat-panel detectors show a drastic change of X-ray photon absorption efficiency around their K-edge energies that consequently affects image quality. Using various tube voltages, we investigated the imaging performance of most popular scintillators: cesium iodide (CsI) and gadolinium oxysulfide (Gd2O2S). The integrated detective quantum efficiencies (iDQE) of four detectors installed in the same hospital were evaluated according to the standardized procedure IEC 62220-1 at tube voltages of 40 - 120 kVp. The iDQE values of the Gd2O2S detectors were normalized by those of CsI detectors to exclude the effects of image postprocessing. The contrast-to-noise ratios (CNR) were also evaluated by using an anthropomorphic chest phantom. The iDQE of the CsI detector outperformed that of the Gd2O2S detector over all tube voltages. Moreover, we noted that the iDQE of the Gd2O2S detectors quickly rolled off with decreasing tube voltage under 70 kVp. The CNRs of the two scintillators were similar at 120 kVp. At 60 kVp, however, the CNR of Gd2O2S was about half that of CsI. Compared to the Gd2O2S detectors, variations in the DQE performance of the CsI detectors were relatively immune to variations in the applied tube voltages. Therefore, we claim that Gd2O2S detectors are inappropriate for use in low-tube-voltage imaging (e.g., extremities and pediatrics) with low patient exposure.

Influence of detector collimation and beam pitch for identification and image quality of ground-glass attenuation and nodules on 16- and 64-detector row CT systems: experimental study using chest phantom.

PubMed

Ohno, Yoshiharu; Koyama, Hisanobu; Kono, Astushi; Terada, Mari; Inokawa, Hiroyasu; Matsumoto, Sumiaki; Sugimura, Kazuro

2007-12-01

The purpose of the present study was to determine the influence of detector collimation and beam pitch for identification and image quality of ground-glass attenuation (GGA) and nodules on 16- and 64-detector row CTs, by using a commercially available chest phantom. A chest CT phantom including simulated GGAs and nodules was scanned with different detector collimations, beam pitches and tube currents. The probability and image quality of each simulated abnormality was visually assessed with a five-point scoring system. ROC-analysis and ANOVA were then performed to compare the identification and image quality of either protocol with standard values. Detection rates of low-dose CTs were significantly reduced when tube currents were set at 40mA or less by using detector collimation 16 and 64x0.5mm and 16 and 32mmx1.0mm for low pitch, and at 100mA or less by using detector collimation 16 and 64x0.5mm and 16 and 32mmx1.0mm for high pitch (p<0.05). Image qualities of low-dose CTs deteriorated significantly when tube current was set at 100mA or less by using detector collimation 16 and 64x0.5mm and 16 and 32x1.0mm for low pitch, and at 150mA or less by using detector collimation 16 and 64x0.5mm and 16 and 32x1.0mm for high pitch (p<0.05). Detector collimation and beam pitch were important factors for the image quality and identification of GGA and nodules by 16- and 64-detector row CT.

High Sensitivity Detection of Broadband Acoustic Vibration Using Optical Demodulation Method

NASA Astrophysics Data System (ADS)

Zhang, Zhen

Measuring the high frequency acoustic vibrations represents the fundamental interest in revealing the intrinsic dynamic characteristic of board range of systems, such as the growth of the fetus, blood flow in human palms, and vibrations of carbon nanotube. However, the acoustic wave detection capability is limited by the detection bandwidth and sensitivity of the commonly used piezoelectric based ultrasound detectors. To overcome these limitations, this thesis focuses on exploring the optical demodulation method for highly sensitive detection of broadband acoustic vibration. First, a transparent optical ultrasonic detector has been developed using micro-ring resonator (MRR) made of soft polymeric materials. It outperforms the traditional piezoelectric detectors with broader detection bandwidth, miniaturized size and wide angular sensitivity. Its ease of integration into photoacoustic microscopy system has resulted in the great improvement of the imaging resolution. A theoretic framework has been developed to establish the quantitative understanding of its unique distance and angular dependent detection characteristics and was subsequently validated experimentally. The developed theoretic framework provides a guideline to fully accounts for the trade-offs between axial and lateral resolution, working distance, and the field of view in developing optimal imaging performance for a wide range of biological and clinical applications. MRR-based ultrasonic detector is further integrated into confocal fluorescence microscopy to realize the simultaneous imaging of fluorescence and optical absorption of retinal pigment epithelium, achieving multi-contrast imaging at sub-cellular level. The needs to resolve the fine details of the biological specimen with the resolution beyond the diffraction limit further motivate the development of optical demodulated ultrasonic detection method based on near-field scanning optical microscopy (NSOM). The nano-focusing probe was developed for adiabatic focusing of surface plasmon polaritons to the probe apex with high energy efficiency and the suppression of the background noise was accomplished through the implementation of the harmonic demodulation technique. Collectively, this system is capable of delivering intense near-field illumination source while effectively suppressing the background signal due to the far-field scattering and thus, allows for quantitative mapping of local evanescent field with enhanced contrast and improved resolutions. The performance of the developed NSOM system has been validated through the experimental measurements of the surface plasmon polariton mode. This new NSOM system enables optical demodulated ultrasound detection at nanoscale spatial resolution. Using it to detect the ultrasound signal within the acoustic near-field has led to the successful experimental demonstration of the sub-surface photoacoustic imaging of buried objects with sub-diffraction-limited resolution and high sensitivity. Such a new ultrasound detection method holds promising potential for super-resolution ultrasound imaging.

Performance Testing of the Astro-H Flight Model 3-Stage ADR

NASA Technical Reports Server (NTRS)

Shirron, Peter J.; Kimball, Mark Oliver; DiPirro, Michael; Bialas, Tom G.

2014-01-01

The Soft X-ray Spectrometer (SXS) is one of four instruments that will be flown on the Japanese Astro-H satellite, planned for launch in late 2015early 2016. The SXS will perform imaging spectroscopy in the soft x-ray band using a 6x6 array of silicon micro calorimeters operated at 50 mK, cooled by an adiabatic demagnetization refrigerator (ADR). NASAGSFC is providing the detector array and ADR, and Sumitomo Heavy Industries, Inc. is providing the remainder of the cryogenic system (superfluid helium dewar (1.3 K), Stirling cryocoolers and a 4.5 K Joule-Thomson (JT) cryocooler). The ADR is unique in that it is designed to use both the liquid helium and the JT cryocooler as it heat sink. The flight detector and ADR assembly have successfully undergone vibration and performance testing at GSFC, and have now undergone initial performance testing with the flight dewar at Sumitomo Heavy Industries, Inc. in Japan. This presentation summarizes the performance of the flight ADR in both cryogen-based and cryogen-free operating modes.

A GPU-Based Architecture for Real-Time Data Assessment at Synchrotron Experiments

NASA Astrophysics Data System (ADS)

Chilingaryan, Suren; Mirone, Alessandro; Hammersley, Andrew; Ferrero, Claudio; Helfen, Lukas; Kopmann, Andreas; Rolo, Tomy dos Santos; Vagovic, Patrik

2011-08-01

Advances in digital detector technology leads presently to rapidly increasing data rates in imaging experiments. Using fast two-dimensional detectors in computed tomography, the data acquisition can be much faster than the reconstruction if no adequate measures are taken, especially when a high photon flux at synchrotron sources is used. We have optimized the reconstruction software employed at the micro-tomography beamlines of our synchrotron facilities to use the computational power of modern graphic cards. The main paradigm of our approach is the full utilization of all system resources. We use a pipelined architecture, where the GPUs are used as compute coprocessors to reconstruct slices, while the CPUs are preparing the next ones. Special attention is devoted to minimize data transfers between the host and GPU memory and to execute memory transfers in parallel with the computations. We were able to reduce the reconstruction time by a factor 30 and process a typical data set of 20 GB in 40 seconds. The time needed for the first evaluation of the reconstructed sample is reduced significantly and quasi real-time visualization is now possible.

X-ray fluorescence microscopy artefacts in elemental maps of topologically complex samples: Analytical observations, simulation and a map correction method

NASA Astrophysics Data System (ADS)

Billè, Fulvio; Kourousias, George; Luchinat, Enrico; Kiskinova, Maya; Gianoncelli, Alessandra

2016-08-01

XRF spectroscopy is among the most widely used non-destructive techniques for elemental analysis. Despite the known angular dependence of X-ray fluorescence (XRF), topological artefacts remain an unresolved issue when using X-ray micro- or nano-probes. In this work we investigate the origin of the artefacts in XRF imaging of topologically complex samples, which are unresolved problems in studies of organic matter due to the limited travel distances of low energy XRF emission from the light elements. In particular we mapped Human Embryonic Kidney (HEK293T) cells. The exemplary results with biological samples, obtained with a soft X-ray scanning microscope installed at a synchrotron facility were used for testing a mathematical model based on detector response simulations, and for proposing an artefact correction method based on directional derivatives. Despite the peculiar and specific application, the methodology can be easily extended to hard X-rays and to set-ups with multi-array detector systems when the dimensions of surface reliefs are in the order of the probing beam size.

Evaluation and Comparison of High-Resolution (HR) and High-Light (HL) Phosphors in the Micro-Angiographic Fluoroscope (MAF) using Generalized Linear Systems Analyses (GMTF, GDQE) that include the Effect of Scatter, Magnification and Detector Characteristics.

PubMed

Gupta, Sandesh K; Jain, Amit; Bednarek, Daniel R; Rudin, Stephen

2011-01-01

In this study, we evaluated the imaging characteristics of the high-resolution, high-sensitivity micro-angiographic fluoroscope (MAF) with 35-micron pixel-pitch when used with different commercially-available 300 micron thick phosphors: the high resolution (HR) and high light (HL) from Hamamatsu. The purpose of this evaluation was to see if the HL phosphor with its higher screen efficiency could be replaced with the HR phosphor to achieve improved resolution without an increase in noise resulting from the HR's decreased light-photon yield. We designated the detectors MAF-HR and MAF-HL and compared them with a standard flat panel detector (FPD) (194 micron pixel pitch and 600 micron thick CsI(Tl)). For this comparison, we used the generalized linear-system metrics of GMTF, GNNPS and GDQE which are more realistic measures of total system performance since they include the effect of scattered radiation, focal spot distribution, and geometric un-sharpness. Magnifications (1.05-1.15) and scatter fractions (0.28 and 0.33) characteristic of a standard head phantom were used. The MAF-HR performed significantly better than the MAF-HL at high spatial frequencies. The ratio of GMTF and GDQE of the MAF-HR compared to the MAF-HL at 3(6) cycles/mm was 1.45(2.42) and 1.23(2.89), respectively. Despite significant degradation by inclusion of scatter and object magnification, both MAF-HR and MAF-HL provide superior performance over the FPD at higher spatial frequencies with similar performance up to the FPD's Nyquist frequency of 2.5 cycles/mm. Both substantially higher resolution and improved GDQE can be achieved with the MAF using the HR phosphor instead of the HL phosphor.

Noise, fluctuation, and HADAMARD-transform spectrometry

NASA Astrophysics Data System (ADS)

Nitzsche, Guenter; Riesenberg, Rainer

2003-05-01

The HADAMARD principle is known in optics as a multiplex technique. It describes the mode with the most advantageous increase of the signal-to-noise ratio (SNR) in terms of scanning (Fellget advantage). The maximum increase of SNR, we call it gain, is (n+1)/(2On), where n is the number of multiplexing. It is valid in the case of pure detector noise. The multiplex encoding Hadamard pattern in case of n = 7 is 1110100, whereby 1 stands for a switched on channel performed by a field selector. The signals of all (switched on) channels are detected by a single detector. n measurement steps with a cyclic change of the pattern is necessary to perform the Hadamard transformation and to get the result of each individual channel. In case of n = 7 the theoretical gain is 1.51. For all possible multiplex pattern (1100000, 1110000 and so on) the gain is theoretically investigated. A multiplexing advantage (gain > 1) is reached only by the Hadamard pattern, the inverse Hadamard pattern and for (0111111)-pattern (gain=1.08). Most of the multiplex pattern are disadvantageous. The reason for maximum gain of the HADAMARD transformation is analysed theoretically. Signal fluctuations during the measurement caused by fluctuations of the illumination or by the object under test, reduce the multiplex gain, too. So the limits for realizing a gain are estimated theoretically. Essential is the transformation procedure and its influence on the error propagation. The results could be verified by experiments with array spectrometeres. Requirements are derived by numerical simulation concerning the stability of the signals to be multiplexed. It is simulated the needed stability of the signals with increasing order of multiplexing. So the increase of the multiplex gain is limited by signal fluctuations. A realized 96 channel spectral reader is presented as a modern application of an optical multiplexing arrangement. ! M. Harvid, N. J. A. Sloane, Hadamard Transform Optics, Academic Press, 1979 ! R.A. De Verse, R.M. Hammaker, W. G. Fately, J.A.Graham, J.D.Tate, "Spectrometry and imaging using a digital micromirror array" American Laboratory, Vol. 30, 21, pp. 112-120, 1998 ! R. Riesenberg, A. Wuttig, B. Harnisch, "Optical MEMS Technology for Multiplexing in High-End Micro-Scpectrometers", Proc. SPIE 4928, 6-14, 2002 ! A. Wuttig, R. Riesenberg, "Hyperspectral imager with a facile MEMS", Proc. SPIE 4881A, 2002, to be published ! R. Riesenberg, G. Nitzsche, W. Voigt, 'HADAMARD Encoding and other optical Multiplexing', VDI-Berichte 1694, pp. 345-350, 2002 ! A. Wuttig, R. Riesenberg, G. Nitzsche, "Subpixel Analysis of Double Array Grating Spectrometer", Proc. SPIE 4480, pp. 334-344, 2002 ! A. Wuttig, R. Riesenberg, G. Nitzsche, "Integral Field and Multi Object Spectrometry with MEMS", Proc. SPIE 4480, pp. 367-376, 2002 ! R. Riesenberg, G. Nitzsche, A. Wuttig, B. Harnisch, "Micro Spectrometer and MEMS for Space" in "Smaller Satellites: Bigger Business?", edited by M. Rycroft, N. Crosby, Kluwer Academic Publisher, pp. 403-406, 2002 ! R. Riesenberg, A. Wuttig, "Optical sensors with MEMS, slit masks and micromechanical devices", Proc. SPIE 4561, pp. 315-322, 2001 ! R. Riesenberg, "MicroMechanical Slit Positioning System as a transmissive spatial Light Modulator", Proc. SPIE 4457, pp.197-203, 2001 ! R. Riesenberg, J. Lonschinski, "HADAMARD-Minispectrometer made by a Micro Device", Proc. "3rd Round Table on Micro/NanoTechnologies for Space", ESTEC, Noordwijk, The Netherlands, pp. 291 - 297, 2000 ! R. Riesenberg, U. Dillner, "HADAMARD Imaging Spectrometers", Proc. SPIE 3753, pp. 203-213, 1999 ! R. Riesenberg, Th. Seifert, "Design of spatial Light Modulator Microdevices - Micro Slit Arrays", Proc. SPIE 3680, Part One, pp. 406-414, 1999 ! R. Riesenberg, W. Voigt, J. Schoneich, "Compact Spectrometers made by Micro System Technology", Sensor 97, Proc. Vol. 2, pp. 145-150,1997

From macro-scale to micro-scale computational anatomy: a perspective on the next 20 years.

PubMed

Mori, Kensaku

2016-10-01

This paper gives our perspective on the next two decades of computational anatomy, which has made great strides in the recognition and understanding of human anatomy from conventional clinical images. The results from this field are now used in a variety of medical applications, including quantitative analysis of organ shapes, interventional assistance, surgical navigation, and population analysis. Several anatomical models have also been used in computational anatomy, and these mainly target millimeter-scale shapes. For example, liver-shape models are almost completely modeled at the millimeter scale, and shape variations are described at such scales. Most clinical 3D scanning devices have had just under 1 or 0.5 mm per voxel resolution for over 25 years, and this resolution has not changed drastically in that time. Although Z-axis (head-to-tail direction) resolution has been drastically improved by the introduction of multi-detector CT scanning devices, in-plane resolutions have not changed very much either. When we look at human anatomy, we can see different anatomical structures at different scales. For example, pulmonary blood vessels and lung lobes can be observed in millimeter-scale images. If we take 10-µm-scale images of a lung specimen, the alveoli and bronchiole regions can be located in them. Most work in millimeter-scale computational anatomy has been done by the medical-image analysis community. In the next two decades, we encourage our community to focus on micro-scale computational anatomy. In this perspective paper, we briefly review the achievements of computational anatomy and its impacts on clinical applications; furthermore, we show several possibilities from the viewpoint of microscopic computational anatomy by discussing experimental results from our recent research activities. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of a metal artifacts reduction algorithm applied to postinterventional flat panel detector CT imaging.

PubMed

Stidd, D A; Theessen, H; Deng, Y; Li, Y; Scholz, B; Rohkohl, C; Jhaveri, M D; Moftakhar, R; Chen, M; Lopes, D K

2014-01-01

Flat panel detector CT images are degraded by streak artifacts caused by radiodense implanted materials such as coils or clips. A new metal artifacts reduction prototype algorithm has been used to minimize these artifacts. The application of this new metal artifacts reduction algorithm was evaluated for flat panel detector CT imaging performed in a routine clinical setting. Flat panel detector CT images were obtained from 59 patients immediately following cerebral endovascular procedures or as surveillance imaging for cerebral endovascular or surgical procedures previously performed. The images were independently evaluated by 7 physicians for metal artifacts reduction on a 3-point scale at 2 locations: immediately adjacent to the metallic implant and 3 cm away from it. The number of visible vessels before and after metal artifacts reduction correction was also evaluated within a 3-cm radius around the metallic implant. The metal artifacts reduction algorithm was applied to the 59 flat panel detector CT datasets without complications. The metal artifacts in the reduction-corrected flat panel detector CT images were significantly reduced in the area immediately adjacent to the implanted metal object (P = .05) and in the area 3 cm away from the metal object (P = .03). The average number of visible vessel segments increased from 4.07 to 5.29 (P = .1235) after application of the metal artifacts reduction algorithm to the flat panel detector CT images. Metal artifacts reduction is an effective method to improve flat panel detector CT images degraded by metal artifacts. Metal artifacts are significantly decreased by the metal artifacts reduction algorithm, and there was a trend toward increased vessel-segment visualization. © 2014 by American Journal of Neuroradiology.

Evaluation of flow with dynamic x-ray imaging for aneurysms

NASA Astrophysics Data System (ADS)

Dohatcu, Andreea Cristina

The main goal of this thesis is to evaluate blood flow inside cerebrovascular aneurysms using dynamic x-ray imaging. X-ray contrast substance (dye) was auto injected in elastomer aneurysm models placed in a flow loop (for in-vitro studies) to trace flow passing through aneurysms. More specifically, an improved Time-Density Curves (TDC) Roentgen-videodensitometric tracking technique, that included looking to designated regions (R) within an aneurysm rather than focusing on the entire aneurysm, was employed to get information about blood flow using cine-angiographic sequences. It is the first time R-TDC technique has been used. In complex real-time interventions on patients, 2D/3D angiographic analysis of contrast media flow is the only reliable and rapid source of information that we have in order to assess the seriousness of the disease, suggest the treatment, and verify the result of the treatment. The present study focused on finding a "correlation metric" to quantitatively describe the flow behavior within the aneurysms and examine the hemodynamic implications of several treatments using flow modulating devices applied to saccular and bifurcation geometries aneurysms. The main idea in treatment of an aneurysm is rapid reduction of the risk of rupture. This is usually done endovascularly now by totally occluding the aneurysm by packing it with mechanical or chemical agents. Our research, however, involves a new method of blocking the neck using various types of asymmetric vascular stents (AVS). We proposed and analyzed, using R-TDCs, the feasibility of a new modified endovascular method of treatment based on alteration of blood flow through the aneurysm by partial occlusion only. In-vitro studies using aneurysm phantoms with patient-specific aneurysm models were performed. Also, for the first time the new methods were used in in-vivo studies as well, on rabbit-model experimental data, in an attempt to correlate thrombogenic response of a living organism to flow characteristics as a result of interaction with an AVS. A comparison with optical-dye-dilution data and 3D Computational Fluid Dynamics virtual angiography (CFD) data in similar conditions was also performed. Task oriented optimization of x-ray system parameters with regard to the needs of obtaining TDCs so as to obtain more accurate information of contrast media flow into aneurysms from angiographic images, were done. This includes a comparison between a commercial x-ray Flat Panel Detector (FPD) and an in-house new x-ray micro detector prototype, the Micro-Angiographic Fluoroscope (MAF). X-ray dose levels given in clinical procedures similar in length and complexity to aneurysm treatments, were studied on a statistical representative batch. It was concluded that there is a need for reduction of radiation-induced skin injuries to patients following interventional procedures. Hence, we developed and assessed a method to evaluate the variation of image quality (which impacts the success of TDC analysis) and dose with the acquisition mode operation logic and the automatic-brightness-control (ABC); this method was applied to two clinical interventional fluoroscopic imaging systems: one with an Image Intensifier (II) and the other with a Flat Panel Detector (FPD). The resultant ABC tracking curves obtained for the various imaging modes available on a given system can then be used for proper selection of technique to achieve the needed contrast signal to noise ratio to acquire adequate data for TDC evaluation, while controlling the patient dose.

Elemental X-ray Imaging Using the Maia Detector Array: The Benefits and Challenges of Large Solid-Angle

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

Ryan, C.G.; De Geronimo, G.; Kirkham, R.

2009-11-13

The fundamental parameter method for quantitative SXRF and PIXE analysis and imaging using the dynamic analysis method is extended to model the changing X-ray yields and detector sensitivity with angle across large detector arrays. The method is implemented in the GeoPIXE software and applied to cope with the large solid-angle of the new Maia 384 detector array and its 96 detector prototype developed by CSIRO and BNL for SXRF imaging applications at the Australian and NSLS synchrotrons. Peak-to-background is controlled by mitigating charge-sharing between detectors through careful optimization of a patterned molybdenum absorber mask. A geological application demonstrates the capabilitymore » of the method to produce high definition elemental images up to {approx}100 M pixels in size.« less

Towards an Optimal Interest Point Detector for Measurements in Ultrasound Images

NASA Astrophysics Data System (ADS)

Zukal, Martin; Beneš, Radek; Číka, Petr; Říha, Kamil

2013-12-01

This paper focuses on the comparison of different interest point detectors and their utilization for measurements in ultrasound (US) images. Certain medical examinations are based on speckle tracking which strongly relies on features that can be reliably tracked frame to frame. Only significant features (interest points) resistant to noise and brightness changes within US images are suitable for accurate long-lasting tracking. We compare three interest point detectors - Harris-Laplace, Difference of Gaussian (DoG) and Fast Hessian - and identify the most suitable one for use in US images on the basis of an objective criterion. Repeatability rate is assumed to be an objective quality measure for comparison. We have measured repeatability in images corrupted by different types of noise (speckle noise, Gaussian noise) and for changes in brightness. The Harris-Laplace detector outperformed its competitors and seems to be a sound option when choosing a suitable interest point detector for US images. However, it has to be noted that Fast Hessian and DoG detectors achieved better results in terms of processing speed.

Design and Construction of Detector and Data Acquisition Elements for Proton Computed Tomography

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

Fermi Research Alliance; Northern Illinois University

2015-07-15

Proton computed tomography (pCT) offers an alternative to x-ray imaging with potential for three-dimensional imaging, reduced radiation exposure, and in-situ imaging. Northern Illinois University (NIU) is developing a second-generation proton computed tomography system with a goal of demonstrating the feasibility of three-dimensional imaging within clinically realistic imaging times. The second-generation pCT system is comprised of a tracking system, a calorimeter, data acquisition, a computing farm, and software algorithms. The proton beam encounters the upstream tracking detectors, the patient or phantom, the downstream tracking detectors, and a calorimeter. The schematic layout of the PCT system is shown. The data acquisition sendsmore » the proton scattering information to an offline computing farm. Major innovations of the second generation pCT project involve an increased data acquisition rate ( MHz range) and development of three-dimensional imaging algorithms. The Fermilab Particle Physics Division and Northern Illinois Center for Accelerator and Detector Development at Northern Illinois University worked together to design and construct the tracking detectors, calorimeter, readout electronics and detector mounting system.« less

Design of an Image Fusion Phantom for a Small Animal microPET/CT Scanner Prototype

NASA Astrophysics Data System (ADS)

Nava-García, Dante; Alva-Sánchez, Héctor; Murrieta-Rodríguez, Tirso; Martínez-Dávalos, Arnulfo; Rodríguez-Villafuerte, Mercedes

2010-12-01

Two separate microtomography systems recently developed at Instituto de Física, UNAM, produce anatomical (microCT) and physiological images (microPET) of small animals. In this work, the development and initial tests of an image fusion method based on fiducial markers for image registration between the two modalities are presented. A modular Helix/Line-Sources phantom was designed and constructed; this phantom contains fiducial markers that can be visualized in both imaging systems. The registration was carried out by solving the rigid body alignment problem of Procrustes to obtain rotation and translation matrices required to align the two sets of images. The microCT/microPET image fusion of the Helix/Line-Sources phantom shows excellent visual coincidence between different structures, showing a calculated target-registration-error of 0.32 mm.

Compact Micro-Imaging Spectrometer (CMIS): Investigation of Imaging Spectroscopy and Its Application to Mars Geology and Astrobiology

NASA Technical Reports Server (NTRS)

Staten, Paul W.

2005-01-01

Future missions to Mars will attempt to answer questions about Mars' geological and biological history. The goal of the CMIS project is to design, construct, and test a capable, multi-spectral micro-imaging spectrometer use in such missions. A breadboard instrument has been constructed with a micro-imaging camera and Several multi-wavelength LED illumination rings. Test samples have been chosen for their interest to spectroscopists, geologists and astrobiologists. Preliminary analysis has demonstrated the advantages of isotropic illumination and micro-imaging spectroscopy over spot spectroscopy.

Real-time single-molecule imaging of quantum interference.

PubMed

Juffmann, Thomas; Milic, Adriana; Müllneritsch, Michael; Asenbaum, Peter; Tsukernik, Alexander; Tüxen, Jens; Mayor, Marcel; Cheshnovsky, Ori; Arndt, Markus

2012-03-25

The observation of interference patterns in double-slit experiments with massive particles is generally regarded as the ultimate demonstration of the quantum nature of these objects. Such matter-wave interference has been observed for electrons, neutrons, atoms and molecules and, in contrast to classical physics, quantum interference can be observed when single particles arrive at the detector one by one. The build-up of such patterns in experiments with electrons has been described as the "most beautiful experiment in physics". Here, we show how a combination of nanofabrication and nano-imaging allows us to record the full two-dimensional build-up of quantum interference patterns in real time for phthalocyanine molecules and for derivatives of phthalocyanine molecules, which have masses of 514 AMU and 1,298 AMU respectively. A laser-controlled micro-evaporation source was used to produce a beam of molecules with the required intensity and coherence, and the gratings were machined in 10-nm-thick silicon nitride membranes to reduce the effect of van der Waals forces. Wide-field fluorescence microscopy detected the position of each molecule with an accuracy of 10 nm and revealed the build-up of a deterministic ensemble interference pattern from single molecules that arrived stochastically at the detector. In addition to providing this particularly clear demonstration of wave-particle duality, our approach could also be used to study larger molecules and explore the boundary between quantum and classical physics.

Real-time single-molecule imaging of quantum interference

NASA Astrophysics Data System (ADS)

Juffmann, Thomas; Milic, Adriana; Müllneritsch, Michael; Asenbaum, Peter; Tsukernik, Alexander; Tüxen, Jens; Mayor, Marcel; Cheshnovsky, Ori; Arndt, Markus

2012-05-01

The observation of interference patterns in double-slit experiments with massive particles is generally regarded as the ultimate demonstration of the quantum nature of these objects. Such matter-wave interference has been observed for electrons, neutrons, atoms and molecules and, in contrast to classical physics, quantum interference can be observed when single particles arrive at the detector one by one. The build-up of such patterns in experiments with electrons has been described as the ``most beautiful experiment in physics''. Here, we show how a combination of nanofabrication and nano-imaging allows us to record the full two-dimensional build-up of quantum interference patterns in real time for phthalocyanine molecules and for derivatives of phthalocyanine molecules, which have masses of 514 AMU and 1,298 AMU respectively. A laser-controlled micro-evaporation source was used to produce a beam of molecules with the required intensity and coherence, and the gratings were machined in 10-nm-thick silicon nitride membranes to reduce the effect of van der Waals forces. Wide-field fluorescence microscopy detected the position of each molecule with an accuracy of 10 nm and revealed the build-up of a deterministic ensemble interference pattern from single molecules that arrived stochastically at the detector. In addition to providing this particularly clear demonstration of wave-particle duality, our approach could also be used to study larger molecules and explore the boundary between quantum and classical physics.

Conversion of mammographic images to appear with the noise and sharpness characteristics of a different detector and x-ray system.

PubMed

Mackenzie, Alistair; Dance, David R; Workman, Adam; Yip, Mary; Wells, Kevin; Young, Kenneth C

2012-05-01

Undertaking observer studies to compare imaging technology using clinical radiological images is challenging due to patient variability. To achieve a significant result, a large number of patients would be required to compare cancer detection rates for different image detectors and systems. The aim of this work was to create a methodology where only one set of images is collected on one particular imaging system. These images are then converted to appear as if they had been acquired on a different detector and x-ray system. Therefore, the effect of a wide range of digital detectors on cancer detection or diagnosis can be examined without the need for multiple patient exposures. Three detectors and x-ray systems [Hologic Selenia (ASE), GE Essential (CSI), Carestream CR (CR)] were characterized in terms of signal transfer properties, noise power spectra (NPS), modulation transfer function, and grid properties. The contributions of the three noise sources (electronic, quantum, and structure noise) to the NPS were calculated by fitting a quadratic polynomial at each spatial frequency of the NPS against air kerma. A methodology was developed to degrade the images to have the characteristics of a different (target) imaging system. The simulated images were created by first linearizing the original images such that the pixel values were equivalent to the air kerma incident at the detector. The linearized image was then blurred to match the sharpness characteristics of the target detector. Noise was then added to the blurred image to correct for differences between the detectors and any required change in dose. The electronic, quantum, and structure noise were added appropriate to the air kerma selected for the simulated image and thus ensuring that the noise in the simulated image had the same magnitude and correlation as the target image. A correction was also made for differences in primary grid transmission, scatter, and veiling glare. The method was validated by acquiring images of a CDMAM contrast detail test object (Artinis, The Netherlands) at five different doses for the three systems. The ASE CDMAM images were then converted to appear with the imaging characteristics of target CR and CSI detectors. The measured threshold gold thicknesses of the simulated and target CDMAM images were closely matched at normal dose level and the average differences across the range of detail diameters were -4% and 0% for the CR and CSI systems, respectively. The conversion was successful for images acquired over a wide dose range. The average difference between simulated and target images for a given dose was a maximum of 11%. The validation shows that the image quality of a digital mammography image obtained with a particular system can be degraded, in terms of noise magnitude and color, sharpness, and contrast to account for differences in the detector and antiscatter grid. Potentially, this is a powerful tool for observer studies, as a range of image qualities can be examined by modifying an image set obtained at a single (better) image quality thus removing the patient variability when comparing systems.

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

Hall, G. N., E-mail: hall98@llnl.gov; Izumi, N.; Landen, O. L.

Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro-channel plate) to provide gating and high DQE at the 40–200 keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Experiments were performed at energiesmore » relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.« less

CCD imaging system for the EUV solar telescope

NASA Astrophysics Data System (ADS)

Gong, Yan; Song, Qian; Ye, Bing-Xun

2006-01-01

In order to develop the detector adapted to the space solar telescope, we have built a CCD camera system capable of working in the extra ultraviolet (EUV) band, which is composed of one phosphor screen, one intensified system using a photocathode/micro-channel plate(MCP)/ phosphor, one optical taper and one chip of front-illuminated (FI) CCD without screen windows. All of them were stuck one by one with optical glue. The working principle of the camera system is presented; moreover we have employed the mesh experiment to calibrate and test the CCD camera system in 15~24nm, the position resolution of about 19 μm is obtained at the wavelength of 17.1nm and 19.5nm.

The High Energy Detector of Simbol-X

NASA Astrophysics Data System (ADS)

Meuris, A.; Limousin, O.; Lugiez, F.; Gevin, O.; Blondel, C.; Le Mer, I.; Pinsard, F.; Cara, C.; Goetschy, A.; Martignac, J.; Tauzin, G.; Hervé, S.; Laurent, P.; Chipaux, R.; Rio, Y.; Fontignie, J.; Horeau, B.; Authier, M.; Ferrando, P.

2009-05-01

The High Energy Detector (HED) is one of the three detection units on board the Simbol-X detector spacecraft. It is placed below the Low Energy Detector so as to collect focused photons in the energy range from 8 to 80 keV. It consists of a mosaic of 64 independent cameras, divided in 8 sectors. Each elementary detection unit, called Caliste, is the hybridization of a 256-pixel Cadmium Telluride (CdTe) detector with full custom front-end electronics into a unique component. The status of the HED design will be reported. The promising results obtained from the first micro-camera prototypes called Caliste 64 and Caliste 256 will be presented to illustrate the expected performance of the instrument.

Physical characteristics of GE Senographe Essential and DS digital mammography detectors.

PubMed

Ghetti, Caterina; Borrini, Adriano; Ortenzia, Ornella; Rossi, Raffaella; Ordóñez, Pedro L

2008-02-01

The purpose of this study was to investigate physical characteristics of two full field digital mammography (FFDM) systems (GE Senographe Essential and DS). Both are indirect conversion (x ray to light) alpha-Si flat panels coupled with a CsI(Tl) scintillator. The examined systems have the same pixel size (100 microm) but a different field of view: a conventional size 23 x 19.2 cm2 and a large field 24 X 30.7 cm2, specifically designed to image large breasts. In the GE Senographe Essential model relevant improvements in flat panel design were implemented and new deposition tools for metal, alpha-Si, and CsI(Tl) were introduced by GE. These changes in detector design are expected to be beneficial for advanced applications such as breast tomosynthesis. The presampling modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were measured for a wide range of exposure (25-240 microGy) with a RQA-M2 technique (28 kVp with a Mo/Mo target/filter combination and 2 mm of additional aluminum filtration). At 1, 2, and at 4 lp/mm MTF is equal to 0.9, 0.76, and 0.46 for the conventional field detector and to 0.85, 0.59, and 0.24 for the large field detector. The latter detector exhibits an improved NNPS due to a lower electronic noise and a better DQE that reaches 60%. In addition a contrast-detail analysis was performed with CDMAM 3.4 phantom and CDCOM software: GE Senographe DS showed statistically significant poorer detection ability in comparison with the GE Senographe Essential. These results could have been expected, at least qualitatively, considering the relative DQE of the two systems.

Photon-Counting H33D Detector for Biological Fluorescence Imaging

PubMed Central

Michalet, X.; Siegmund, O.H.W.; Vallerga, J.V.; Jelinsky, P.; Millaud, J.E.; Weiss, S.

2010-01-01

We have developed a photon-counting High-temporal and High-spatial resolution, High-throughput 3-Dimensional detector (H33D) for biological imaging of fluorescent samples. The design is based on a 25 mm diameter S20 photocathode followed by a 3-microchannel plate stack, and a cross delay line anode. We describe the bench performance of the H33D detector, as well as preliminary imaging results obtained with fluorescent beads, quantum dots and live cells and discuss applications of future generation detectors for single-molecule imaging and high-throughput study of biomolecular interactions. PMID:20151021

Imaging detectors and electronics—a view of the future

NASA Astrophysics Data System (ADS)

Spieler, Helmuth

2004-09-01

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

A PET system based on 2-18FDG production with a low energy electrostatic proton accelerator and a dual headed PET scanner.

PubMed

Sandell, A; Ohlsson, T; Erlandsson, K; Hellborg, R; Strand, S E

1992-01-01

We have developed a comparatively inexpensive PET system, based on a rotating scanner with two scintillation camera heads, and a nearby low energy electrostatic proton accelerator for production of short-lived radionuclides. Using a 6 MeV proton beam of 5 microA, and by optimization of the target geometry for the 18O(p,n)18F reaction, 750 MBq of 2-18FDG can be obtained. The PET scanner shows a spatial resolution of 6 mm (FWHM) and a sensitivity of 80 s-1kBq-1ml-1 (3 kcps/microCi/ml). Various corrections are included in the imaging process, to compensate for spatial and temporal response variations in the detector system. Both filtered backprojection and iterative reconstruction methods are employed. Clinical studies have been performed with acquisition times of 30-40 min. The system will be used for clinical experimental research with short- as well as long-lived positron emitters. Also the possibility of true 3D reconstruction is under evaluation.

Ultraviolet micro-Raman spectrograph for the detection of small numbers of bacterial cells

NASA Astrophysics Data System (ADS)

Chadha, S.; Nelson, W. H.; Sperry, J. F.

1993-11-01

The construction of a practical UV micro-Raman spectrograph capable of selective excitation of bacterial cells and other microscopic samples has been described. A reflective objective is used to focus cw laser light on a sample and at the same time collect the scattered light at 180°. With the aid of a quartz lens the image produced is focused on the slits of a spectrograph equipped with a single 2400 grooves/mm grating optimized for 250 nm. Spectra were detected by means of a blue-intensified diode array detector. Resonance Raman spectra of Bacillus subtilis and Flavobacterium capsulatum excited by the 257.2 nm output of a cw laser were recorded in the 900-1800 cm-1 region. Bacterial cells were immobilized on a quartz plate by means of polylysine and were counted visually. Cooling was required to retard sample degradation. Sample sizes ranged from 1 to 50 cells with excitation times varying from 15 to 180 s. Excellent spectra have been obtained from 20 cells in 15 s using a spectrograph having only 3% throughput.

Color camera computed tomography imaging spectrometer for improved spatial-spectral image accuracy

NASA Technical Reports Server (NTRS)

Wilson, Daniel W. (Inventor); Bearman, Gregory H. (Inventor); Johnson, William R. (Inventor)

2011-01-01

Computed tomography imaging spectrometers ("CTIS"s) having color focal plane array detectors are provided. The color FPA detector may comprise a digital color camera including a digital image sensor, such as a Foveon X3.RTM. digital image sensor or a Bayer color filter mosaic. In another embodiment, the CTIS includes a pattern imposed either directly on the object scene being imaged or at the field stop aperture. The use of a color FPA detector and the pattern improves the accuracy of the captured spatial and spectral information.

Investigation of ultra low-dose scans in the context of quantum-counting clinical CT

NASA Astrophysics Data System (ADS)

Weidinger, T.; Buzug, T. M.; Flohr, T.; Fung, G. S. K.; Kappler, S.; Stierstorfer, K.; Tsui, B. M. W.

2012-03-01

In clinical computed tomography (CT), images from patient examinations taken with conventional scanners exhibit noise characteristics governed by electronics noise, when scanning strongly attenuating obese patients or with an ultra-low X-ray dose. Unlike CT systems based on energy integrating detectors, a system with a quantum counting detector does not suffer from this drawback. Instead, the noise from the electronics mainly affects the spectral resolution of these detectors. Therefore, it does not contribute to the image noise in spectrally non-resolved CT images. This promises improved image quality due to image noise reduction in scans obtained from clinical CT examinations with lowest X-ray tube currents or obese patients. To quantify the benefits of quantum counting detectors in clinical CT we have carried out an extensive simulation study of the complete scanning and reconstruction process for both kinds of detectors. The simulation chain encompasses modeling of the X-ray source, beam attenuation in the patient, and calculation of the detector response. Moreover, in each case the subsequent image preprocessing and reconstruction is modeled as well. The simulation-based, theoretical evaluation is validated by experiments with a novel prototype quantum counting system and a Siemens Definition Flash scanner with a conventional energy integrating CT detector. We demonstrate and quantify the improvement from image noise reduction achievable with quantum counting techniques in CT examinations with ultra-low X-ray dose and strong attenuation.

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

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

[Near infrared spectroscopy system structure with MOEMS scanning mirror array].

PubMed

Luo, Biao; Wen, Zhi-Yu; Wen, Zhong-Quan; Chen, Li; Qian, Rong-Rong

2011-11-01

A method which uses MOEMS mirror array optical structure to reduce the high cost of infrared spectrometer is given in the present paper. This method resolved the problem that MOEMS mirror array can not be used in simple infrared spectrometer because the problem of imaging irregularity in infrared spectroscopy and a new structure for spectral imaging was designed. According to the requirements of imaging spot, this method used optical design software ZEMAX and standard-specific aberrations of the optimization algorithm, designed and optimized the optical structure. It works from 900 to 1 400 nm. The results of design analysis showed that with the light source slit width of 50 microm, the spectrophotometric system is superior to the theoretical resolution of 6 nm, and the size of the available spot is 0.042 mm x 0.08 mm. Verification examples show that the design meets the requirements of the imaging regularity, and can be used for MOEMS mirror reflectance scan. And it was also verified that the use of a new MOEMS mirror array spectrometer model is feasible. Finally, analyze the relationship between the location of the detector and the maximum deflection angle of micro-mirror was analyzed.

Performance modelling of miniaturized flash-imaging lidars for future mars exploration missions

NASA Astrophysics Data System (ADS)

Mitev, V.; Pollini, A.; Haesler, J.; Pereira do Carmo, João.

2017-11-01

Future planetary exploration missions require the support of 3D vision in the GN&C during key spacecraft's proximity phases, namely: i) spacecraft precision and soft Landing on the planet's surface; ii) Rendezvous and Docking (RVD) between a Sample Canister (SC) and an orbiter spacecraft; iii) Rover Navigation (RN) on planetary surface. The imaging LiDARs are among the best candidate for such tasks [1-3]. The combination of measurement requirements and environmental conditions seems to find its optimum in the flash 3D LiDAR architecture. Here we present key steps is the evaluation of novelty light detectors and MOEMS (Micro-Opto- Electro-Mechanical Systems) technologies with respect to LiDAR system performance and miniaturization. The objectives of the project MILS (Miniaturized Imaging LiDAR System, Phase 1) concentrated on the evaluation of novel detection and scanning technologies for the miniaturization of 3D LiDARs intended for planetary mission. Preliminary designs for an elegant breadboard (EBB) for the three tasks stated above (Landing, RVD and RN) were proposed, based on results obtained with a numerical model developed in the project and providing the performances evaluation of imaging LiDARs.

Synthesis and quality control of fluorodeoxyglucose and performance assessment of Siemens MicroFocus 220 small animal PET scanner

NASA Astrophysics Data System (ADS)

Phaterpekar, Siddhesh Nitin

The scope of this article is to cover the synthesis and quality control procedures involved in production of Fludeoxyglucose (18F--FDG). The article also describes the cyclotron production of 18F radioisotope and gives a brief overview on operations and working of a fixed energy medical cyclotron. The quality control procedures for FDG involve radiochemical and radionuclidic purity tests, pH tests, chemical purity tests, sterility tests, endotoxin tests. Each of these procedures were carried out for multiple batches of FDG with a passing rate of 95% among 20 batches. The article also covers the quality assurance steps for the Siemens MicroPET Focus 220 Scanner using a Jaszczak phantom. We have carried out spatial resolution tests on the scanner, with an average transaxial resolution of 1.775mm with 2-3mm offset. Tests involved detector efficiency, blank scan sinograms and transmission sinograms. A series of radioactivity distribution tests are also carried out on a uniform phantom, denoting the variations in radioactivity and uniformity by using cylindrical ROIs in the transverse region of the final image. The purpose of these quality control tests is to make sure the manufactured FDG is biocompatible with the human body. Quality assurance tests are carried on PET scanners for efficient performance, and to make sure the quality of images acquired is according to the radioactivity distribution in the subject of interest.

Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays

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

Sathishkumar, P.; Punyabrahma, P.; Sri Muthu Mrinalini, R.

A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array.

Mid-Infrared Tunable Resonant Cavity Enhanced Detectors

PubMed Central

Quack, Niels; Blunier, Stefan; Dual, Jurg; Felder, Ferdinand; Arnold, Martin; Zogg, Hans

2008-01-01

Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED) principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed by two mirrors. The active layer is grown onto one mirror, while the second mirror can be displaced. This changes the cavity length thus shifting the resonances where the detector is sensitive. Using electrostatically actuated MEMS micromirrors, a very compact tunable detector system has been fabricated. Mirror movements of more than 3 μm at 30V are obtained. With these mirrors, detectors with a wavelength tuning range of about 0.7 μm have been realized. Single detectors can be used in mid-infrared micro spectrometers, while a detector arrangement in an array makes it possible to realize Adaptive Focal Plane Arrays (AFPA). PMID:27873824

Synthesis of nanostructured barium phosphate and its application in micro-computed tomography of mouse brain vessels in ex vivo

NASA Astrophysics Data System (ADS)

Zhu, Bangshang; Yuan, Falei; Yuan, Xiaoya; Bo, Yang; Wang, Yongting; Yang, Guo-Yuan; Drummen, Gregor P. C.; Zhu, Xinyuan

2014-02-01

Micro-computed tomography (micro-CT) is a powerful tool for visualizing the vascular systems of tissues, organs, or entire small animals. Vascular contrast agents play a vital role in micro-CT imaging in order to obtain clear and high-quality images. In this study, a new kind of nanostructured barium phosphate was fabricated and used as a contrast agent for ex vivo micro-CT imaging of blood vessels in the mouse brain. Nanostructured barium phosphate was synthesized through a simple wet precipitation method using Ba(NO3)2, and (NH4)2HPO4 as starting materials. The physiochemical properties of barium phosphate were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis. Furthermore, the impact of the produced nanostructures on cell viability was evaluated via the MTT assay, which generally showed low to moderate cytotoxicity. Finally, the animal test images demonstrated that the use of nanostructured barium phosphate as a contrast agent in Micro-CT imaging produced sharp images with excellent contrast. Both major vessels and the microvasculature were clearly observable in the imaged mouse brain. Overall, the results indicate that nanostructured barium phosphate is a potential and useful vascular contrast agent for micro-CT imaging.

A MAPS Based Micro-Vertex Detector for the STAR Experiment

DOE PAGES

Schambach, Joachim; Anderssen, Eric; Contin, Giacomo; ...

2015-06-18

For the 2014 heavy ion run of RHIC a new micro-vertex detector called the Heavy Flavor Tracker (HFT) was installed in the STAR experiment. The HFT consists of three detector subsystems with various silicon technologies arranged in 4 approximately concentric cylinders close to the STAR interaction point designed to improve the STAR detector’s vertex resolution and extend its measurement capabilities in the heavy flavor domain. The two innermost HFT layers are placed at radii of 2.8 cm and 8 cm from the beam line. These layers are constructed with 400 high resolution sensors based on CMOS Monolithic Active Pixel Sensormore » (MAPS) technology arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors to cover a total silicon area of 0.16 m 2. Each sensor of this PiXeL (“PXL”) sub-detector combines a pixel array of 928 rows and 960 columns with a 20.7 μm pixel pitch together with front-end electronics and zero-suppression circuitry in one silicon die providing a sensitive area of ~3.8 cm 2. This sensor architecture features 185.6 μs readout time and 170 mW/cm 2 power dissipation. This low power dissipation allows the PXL detector to be air-cooled, and with the sensors thinned down to 50 μm results in a global material budget of only 0.4% radiation length per layer. A novel mechanical approach to detector insertion allows us to effectively install and integrate the PXL sub-detector within a 12 hour period during an on-going multi-month data taking period. The detector requirements, architecture and design, as well as the performance after installation, are presented in this paper.« less

Extracting alveolar structure of human lung tissue specimens based on surface skeleton representation from 3D micro-CT images

NASA Astrophysics Data System (ADS)

Ishimori, Hiroyuki; Kawata, Yoshiki; Niki, Noboru; Nakaya, Yoshihiro; Ohmatsu, Hironobu; Matsui, Eisuke; Fujii, Masashi; Moriyama, Noriyuki

2007-03-01

We have developed a Micro CT system for understanding lung function at a high resolution of the micrometer order (up to 5µm in spatial resolution). Micro CT system enables the removal specimen of lungs to be observed at micro level, has expected a big contribution for micro internal organs morphology and the image diagnosis study. In this research, we develop system to visualize lung microstructures in three dimensions from micro CT images and analyze them. They characterize in that high CT value of the noise area is, and the difficulty of only using threshold processing to extract the alveolar wall of micro CT images. Thus, we are developing a method of extracting the alveolar wall with surface thinning algorithm. In this report, we propose the method which reduces the excessive degeneracy of figure which caused by surface thinning process. And, we apply this algorithm to the micro CT image of the actual pulmonary specimen. It is shown that the extraction of the alveolus wall becomes possible in the high precision.

Multispectral computational ghost imaging with multiplexed illumination

NASA Astrophysics Data System (ADS)

Huang, Jian; Shi, Dongfeng

2017-07-01

Computational ghost imaging has attracted wide attention from researchers in many fields over the last two decades. Multispectral imaging as one application of computational ghost imaging possesses spatial and spectral resolving abilities, and is very useful for surveying scenes and extracting detailed information. Existing multispectral imagers mostly utilize narrow band filters or dispersive optical devices to separate light of different wavelengths, and then use multiple bucket detectors or an array detector to record them separately. Here, we propose a novel multispectral ghost imaging method that uses one single bucket detector with multiplexed illumination to produce a colored image. The multiplexed illumination patterns are produced by three binary encoded matrices (corresponding to the red, green and blue colored information, respectively) and random patterns. The results of the simulation and experiment have verified that our method can be effective in recovering the colored object. Multispectral images are produced simultaneously by one single-pixel detector, which significantly reduces the amount of data acquisition.

Detectors for Particle Radiation

NASA Astrophysics Data System (ADS)

Kleinknecht, Konrad

1999-01-01

This textbook provides a clear, concise and comprehensive review of the physical principles behind the devices used to detect charged particles and gamma rays, and the construction and performance of these many different types of detectors. Detectors for high-energy particles and radiation are used in many areas of science, especially particle physics and nuclear physics experiments, nuclear medicine, cosmic ray measurements, space sciences and geological exploration. This second edition includes all the latest developments in detector technology, including several new chapters covering micro-strip gas chambers, silicion strip detectors and CCDs, scintillating fibers, shower detectors using noble liquid gases, and compensating calorimeters for hadronic showers. This well-illustrated textbook contains examples from the many areas in science in which these detectors are used. It provides both a coursebook for students in physics, and a useful introduction for researchers in other fields.

Saliency image of feature building for image quality assessment

NASA Astrophysics Data System (ADS)

Ju, Xinuo; Sun, Jiyin; Wang, Peng

2011-11-01

The purpose and method of image quality assessment are quite different for automatic target recognition (ATR) and traditional application. Local invariant feature detectors, mainly including corner detectors, blob detectors and region detectors etc., are widely applied for ATR. A saliency model of feature was proposed to evaluate feasibility of ATR in this paper. The first step consisted of computing the first-order derivatives on horizontal orientation and vertical orientation, and computing DoG maps in different scales respectively. Next, saliency images of feature were built based auto-correlation matrix in different scale. Then, saliency images of feature of different scales amalgamated. Experiment were performed on a large test set, including infrared images and optical images, and the result showed that the salient regions computed by this model were consistent with real feature regions computed by mostly local invariant feature extraction algorithms.

Imaging arrangement and microscope

DOEpatents

Pertsinidis, Alexandros; Chu, Steven

2015-12-15

An embodiment of the present invention is an imaging arrangement that includes imaging optics, a fiducial light source, and a control system. In operation, the imaging optics separate light into first and second tight by wavelength and project the first and second light onto first and second areas within first and second detector regions, respectively. The imaging optics separate fiducial light from the fiducial light source into first and second fiducial light and project the first and second fiducial light onto third and fourth areas within the first and second detector regions, respectively. The control system adjusts alignment of the imaging optics so that the first and second fiducial light projected onto the first and second detector regions maintain relatively constant positions within the first and second detector regions, respectively. Another embodiment of the present invention is a microscope that includes the imaging arrangement.

Results from the First Beam-Induced Reconstructed Tracks in the LHCb Vertex Locator

NASA Astrophysics Data System (ADS)

Rodrigues, E.

2010-04-01

LHCb is a dedicated experiment at the LHC to study CP violation and rare b decays. The vertex locator (VELO) is a silicon strip detector designed to measure precisely the production and decay vertices of B-mesons. The detector is positioned at 8 mm of the LHC beams and will operate in an extremely harsh radiation environment. The VELO consists of two retractable detector halves with 21 silicon micro-strip tracking modules each. A module is composed of two n+-on-n 300 μm thick half disc sensors with R and Φ micro-strip geometry. The detectors are operated in vacuum and a bi-phase CO2 cooling system is used. The full system has been operated since June 2008 and its commissioning experience will be reported. During the LHC synchronization tests in August and September 2008, and June 2009 the LHCb detectors measured secondary particles produced by the interaction of the LHC primary beam on a beam dump. About 50,000 tracks were reconstructed in the VELO and they were used to derive the relative timing alignment between the sensors and for the first evaluation of the spatial alignment. Using this track sample the VELO has been aligned to an accuracy of 5 μm. A single hit resolution of 10 μm was obtained at the smallest pitch for tracks of perpendicular incidence. The design and the main components of the detector system are introduced. The commissioning of the detector is reported and the talk will focus on the results obtained using the first beam-induced reconstructed tracks.

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

Vandervoort, E.; Szanto, J.; Christiansen, E.

Plastic scintillation dosimeters (PSDs) have favourable characteristics for small and composite field dosimetry in radiosurgery, however, imperfect corrections for the Cerenkov radiation contamination could limit their accuracy for complex deliveries. In this work, we characterize the dose and dose-rate linearity, directional dependence, and compare output factors with other stereotactic detectors for a new commercially available PSD (Exradin W1). We provide some preliminary comparisons of planned and measured dose for composite fields delivered clinically by a Cyberknife radiosurgery system. The W1 detector shows good linearity with dose (<0.5%) and dose rate (<0.8%) relative to the signal obtained using an ion chambermore » under the same conditions. A maximum difference of 2% was observed depending on the detector's angular orientation. Output factors for all detectors agree within a range of ±3.2% and ±1.5% for the 5 and 7.5 mm collimators, respectively, provided Monte-Carlo corrections for detector effects are applied to diode and ion chambers (without corrections the range is ±5.5% and ±3.1% for these two collimators). For clinical beam deliveries using 5 and 7.5 mm collimators, four of the six patients showed better agreement with planned dose for the PSD detector compared to a micro ion chamber. Two of the six patients investigated, however, showed 5% differences between PSD and planned dose, film measurements and the ratio of PSD and micro ion chamber signal suggest that further investigation is warranted for these plans. The W1 detector is a promising tool for stereotactic plan verification under the challenging dosimetric conditions of stereotactic radiosurgery.« less

Method and apparatus for enhanced sensitivity filmless medical x-ray imaging, including three-dimensional imaging

DOEpatents

Parker, S.

1995-10-24

A filmless X-ray imaging system includes at least one X-ray source, upper and lower collimators, and a solid-state detector array, and can provide three-dimensional imaging capability. The X-ray source plane is distance z{sub 1} above upper collimator plane, distance z{sub 2} above the lower collimator plane, and distance z{sub 3} above the plane of the detector array. The object to be X-rayed is located between the upper and lower collimator planes. The upper and lower collimators and the detector array are moved horizontally with scanning velocities v{sub 1}, v{sub 2}, v{sub 3} proportional to z{sub 1}, z{sub 2} and z{sub 3}, respectively. The pattern and size of openings in the collimators, and between detector positions is proportional such that similar triangles are always defined relative to the location of the X-ray source. X-rays that pass through openings in the upper collimator will always pass through corresponding and similar openings in the lower collimator, and thence to a corresponding detector in the underlying detector array. Substantially 100% of the X-rays irradiating the object (and neither absorbed nor scattered) pass through the lower collimator openings and are detected, which promotes enhanced sensitivity. A computer system coordinates repositioning of the collimators and detector array, and X-ray source locations. The computer system can store detector array output, and can associate a known X-ray source location with detector array output data, to provide three-dimensional imaging. Detector output may be viewed instantly, stored digitally, and/or transmitted electronically for image viewing at a remote site. 5 figs.

Method and apparatus for enhanced sensitivity filmless medical x-ray imaging, including three-dimensional imaging

DOEpatents

Parker, Sherwood

1995-01-01

A filmless X-ray imaging system includes at least one X-ray source, upper and lower collimators, and a solid-state detector array, and can provide three-dimensional imaging capability. The X-ray source plane is distance z.sub.1 above upper collimator plane, distance z.sub.2 above the lower collimator plane, and distance z.sub.3 above the plane of the detector array. The object to be X-rayed is located between the upper and lower collimator planes. The upper and lower collimators and the detector array are moved horizontally with scanning velocities v.sub.1, v.sub.2, v.sub.3 proportional to z.sub.1, z.sub.2 and z.sub.3, respectively. The pattern and size of openings in the collimators, and between detector positions is proportional such that similar triangles are always defined relative to the location of the X-ray source. X-rays that pass through openings in the upper collimator will always pass through corresponding and similar openings in the lower collimator, and thence to a corresponding detector in the underlying detector array. Substantially 100% of the X-rays irradiating the object (and neither absorbed nor scattered) pass through the lower collimator openings and are detected, which promotes enhanced sensitivity. A computer system coordinates repositioning of the collimators and detector array, and X-ray source locations. The computer system can store detector array output, and can associate a known X-ray source location with detector array output data, to provide three-dimensional imaging. Detector output may be viewed instantly, stored digitally, and/or transmitted electronically for image viewing at a remote site.

TU-E-217BCD-06: Cone Beam Breast CT with a High Resolution Flat Panel Detector-Improvement of Calcification Visibility.

PubMed

Shen, Y; Zhong, Y; Lai, C; Wang, T; Shaw, C

2012-06-01

To investigate the advantage of a high resolution flat panel detector for improving the visibility of microcalcifications (MCs) in cone beam breast CT Methods: A paraffin cylinder was used to simulate a 100% adipose breast. Calcium carbonate grains, ranging from 125-140 μm to 224 - 250 μm in size, were used to simulate the MCs. Groups of 25 same size MCs were embedded at the phantom center. The phantom was scanned with a bench-top CBCT system at various exposure levels. A 75μm pitch flat panel detector (Dexela 2923, Perkin Elmer) with 500μm thick CsI scintillator plate was used as the high resolution detector. A 194 μm pitch detector (Paxscan 4030CB, Varian Medical Systems) was used for reference. 300 projection images were acquired over 360° and reconstructed. The images were reviewed by 6 readers. The MC visibility was quantified as the fraction of visible MCs and averaged for comparison. The visibility was plotted as a function of the estimated dose level for various MC sizes and detectors. The MTFs and DQEs were measured and compared. For imaging small (200 μm and smaller) MCs, the visibility achieved with the 75μm pitch detector was found to be significantly higher than those achieved with the 194μm pitch detector. For imaging larger MCs, there was little advantage in using the 75μm pitch detector. Using the 75μm pitch detector, MCs as small as 180 μm could be imaged to achieve a visibility of 78% with an isocenter tissue dose of ∼20 mGys versus 62% achieved with the 194 μm pitch detector at the same dose level. It was found that a high pitch flat panel detector had the advantages of extending its imaging capability to higher frequencies thus helping improve the visibility when used to image small MCs. This work was supported in part by grants CA104759, CA13852 and CA124585 from NIH-NCI, a grant EB00117 from NIH-NIBIB, and a subcontract from NIST-ATP. © 2012 American Association of Physicists in Medicine.

A novel dual-detector micro-spectrometer

NASA Astrophysics Data System (ADS)

Otto, Thomas; Saupe, Ray; Stock, Volker; Bruch, Reinhard; Gruska, Bernd; Gessner, Thomas

2005-01-01

Infrared analysis is a well-established tool for measuring composition and purity of various materials in industrial-, medical- and environmental applications. Traditional spectrometers, for example Fourier Transform Infrared (FTIR) Instruments are mainly designed for laboratory use and are generally, too large, heavy, costly and delicate to handle for remote applications. With important advances in the miniaturization, ruggedness and cost efficiency we have designed and created a new type of a micromirror spectrometer that can operate in harsh temperature and vibrating environments This device is ideally suited for environmental monitoring, chemical and biological applications as well as detection of biological warfare agents and sensing in important security locations In order to realize such compact, portable and field-deployable spectrometers we have applied MOEMS technology. Thus our novel dual detector micro mirror system is composed of a scanning micro mirror combined with a diffraction grating and other essential optical components in order to miniaturize the basic modular set-up. Especially it periodically disperses polychromatic radiation into its spectral components, which are measured by a combination of a visible (VIS) and near infrared (NIR) single element detector. By means of integrated preamplifiers high-precise measurements over a wide dynamic wavelength range are possible. In addition the spectrometer, including the radiation source, detectors and electronics can be coupled to a minimum-volume liquid or gas-flow cell. Furthermore a SMA connector as a fiber optical input allows easy attachment of fiber based probes. By utilizing rapid prototyping techniques, where all components are directly integrated, the micro mirror spectrometer is manufactured for the 700-1700 nm spectral range. In this work the advanced optical design and integration of the electronic interface will be reviewed. Furthermore we will demonstrate the performance of the system and present characteristic measurement results. Finally advanced packaging issues and test results of the device will be discussed.

Advances in photo-thermal infrared imaging microspectroscopy

NASA Astrophysics Data System (ADS)

Furstenberg, Robert; Kendziora, Chris; Papantonakis, Michael; Nguyen, Viet; McGill, Andrew

2013-05-01

There is a growing need for chemical imaging techniques in many fields of science and technology: forensics, materials science, pharmaceutical and chemical industries, just to name a few. While FTIR micro-spectroscopy is commonly used, its practical resolution limit of about 20 microns or more is often insufficient. Raman micro-spectroscopy provides better spatial resolution (~1 micron), but is not always practical because of samples exhibiting fluorescence or low Raman scattering efficiency. We are developing a non-contact and non-destructive technique we call photo-thermal infrared imaging spectroscopy (PT-IRIS). It involves photo-thermal heating of the sample with a tunable quantum cascade laser and measuring the resulting increase in thermal emission with an infrared detector. Photo-thermal emission spectra resemble FTIR absorbance spectra and can be acquired in both stand-off and microscopy configurations. Furthermore, PT-IRIS allows the acquisition of absorbance-like photo-thermal spectra in a reflected geometry, suitable for field applications and for in-situ study of samples on optically IR-opaque substrates (metals, fabrics, paint, glass etc.). Conventional FTIR microscopes in reflection mode measure the reflectance spectra which are different from absorbance spectra and are usually not catalogued in FTIR spectral libraries. In this paper, we continue developing this new technique. We perform a series of numerical simulations of the laser heating of samples during photo-thermal microscopy. We develop parameterized formulas to help the user pick the appropriate laser illumination power. We also examine the influence of sample geometry on spectral signatures. Finally, we measure and compare photo-thermal and reflectance spectra for two test samples.

Characterization of a hybrid energy-resolving photon-counting detector

NASA Astrophysics Data System (ADS)

Zang, A.; Pelzer, G.; Anton, G.; Ballabriga Sune, R.; Bisello, F.; Campbell, M.; Fauler, A.; Fiederle, M.; Llopart Cudie, X.; Ritter, I.; Tennert, F.; Wölfel, S.; Wong, W. S.; Michel, T.

2014-03-01

Photon-counting detectors in medical x-ray imaging provide a higher dose efficiency than integrating detectors. Even further possibilities for imaging applications arise, if the energy of each photon counted is measured, as for example K-edge-imaging or optimizing image quality by applying energy weighting factors. In this contribution, we show results of the characterization of the Dosepix detector. This hybrid photon- counting pixel detector allows energy resolved measurements with a novel concept of energy binning included in the pixel electronics. Based on ideas of the Medipix detector family, it provides three different modes of operation: An integration mode, a photon-counting mode, and an energy-binning mode. In energy-binning mode, it is possible to set 16 energy thresholds in each pixel individually to derive a binned energy spectrum in every pixel in one acquisition. The hybrid setup allows using different sensor materials. For the measurements 300 μm Si and 1 mm CdTe were used. The detector matrix consists of 16 x 16 square pixels for CdTe (16 x 12 for Si) with a pixel pitch of 220 μm. The Dosepix was originally intended for applications in the field of radiation measurement. Therefore it is not optimized towards medical imaging. The detector concept itself still promises potential as an imaging detector. We present spectra measured in one single pixel as well as in the whole pixel matrix in energy-binning mode with a conventional x-ray tube. In addition, results concerning the count rate linearity for the different sensor materials are shown as well as measurements regarding energy resolution.

Applications of penetrating radiation for small animal imaging

NASA Astrophysics Data System (ADS)

Hasegawa, Bruce H.; Wu, Max C.; Iwata, Koji; Hwang, Andrew B.; Wong, Kenneth H.; Barber, William C.; Dae, Michael W.; Sakdinawat, Anne E.

2002-11-01

Researchers long have relied on research involving small animals to unravel scientific mysteries in the biological sciences, and to develop new diagnostic and therapeutic techniques in the medical and health sciences. Within the past 2 decades, new techniques have been developed to manipulate the genome of the mouse, allowing the development of transgenic and knockout models of mammalian and human disease, development, and physiology. Traditionally, much biological research involving small animals has relied on the use of invasive methods such as organ harvesting, tissue sampling, and autoradiography during which the animal was sacrificed to perform a single measurement. More recently, imaging techniques have been developed that assess anatomy and physiology in the intact animal, in a way that allows the investigator to follow the progression of disease, or to monitor the response to therapeutic interventions. Imaging techniques that use penetrating radiation at millimeter or submillimeter levels to image small animals include x-ray computed tomography (microCT), single-photon emission computed tomography (microSPECT), and imaging positron emission computed tomography (microPET). MicroCT generates cross-sectional slices which reveal the structure of the object with spatial resolution in the range of 50 to 100 microns. MicroSPECT and microPET are radionuclide imaging techniques in which a radiopharmaceutical is injected into the animal that is accumulated to metabolism, blood flow, bone remodeling, tumor growth, or other biological processes. Both microSPECT and microPET offer spatial resolutions in the range of 1-2 millimeters. However, microPET records annihilation photons produced by a positron-emitting radiopharmaceutical using electronic coincidence, and has a sensitivity approximately two orders of magnitude better than microSPECT, while microSPECT is compatible with gamma-ray emitting radiopharmaceuticals that are less expensive and more readily available than those used with microPET. High-resolution dual-modality imaging systems now are being developed that combine microPET or microSPECT with microCT in a way that facilitates more direct correlation of anatomy and physiology in the same animal. Small animal imaging allows researchers to perform experiments that are not possible with conventional invasive techniques, and thereby are becoming increasingly important tools for discovery of fundamental biological information, and development of new diagnostic and therapeutic techniques in the biomedical sciences.

Optimized Detector Angular Configuration Increases the Sensitivity of X-ray Fluorescence Computed Tomography (XFCT).

PubMed

Ahmad, Moiz; Bazalova-Carter, Magdalena; Fahrig, Rebecca; Xing, Lei

2015-05-01

In this work, we demonstrated that an optimized detector angular configuration based on the anisotropic energy distribution of background scattered X-rays improves X-ray fluorescence computed tomography (XFCT) detection sensitivity. We built an XFCT imaging system composed of a bench-top fluoroscopy X-ray source, a CdTe X-ray detector, and a phantom motion stage. We imaged a 6.4-cm-diameter phantom containing different concentrations of gold solution and investigated the effect of detector angular configuration on XFCT image quality. Based on our previous theoretical study, three detector angles were considered. The X-ray fluorescence detector was first placed at 145 (°) (approximating back-scatter) to minimize scatter X-rays. XFCT image quality was compared to images acquired with the detector at 60 (°) (forward-scatter) and 90 (°) (side-scatter). The datasets for the three different detector positions were also combined to approximate an isotropically arranged detector. The sensitivity was optimized with detector in the 145 (°) back-scatter configuration counting the 78-keV gold Kβ1 X-rays. The improvement arose from the reduced energy of scattered X-ray at the 145 (°) position and the large energy separation from gold K β1 X-rays. The lowest detected concentration in this configuration was 2.5 mgAu/mL (or 0.25% Au with SNR = 4.3). This concentration could not be detected with the 60 (°) , 90 (°) , or isotropic configurations (SNRs = 1.3, 0, 2.3, respectively). XFCT imaging dose of 14 mGy was in the range of typical clinical X-ray CT imaging doses. To our knowledge, the sensitivity achieved in this experiment is the highest in any XFCT experiment using an ordinary bench-top X-ray source in a phantom larger than a mouse ( > 3 cm).