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https://www.readbyqxmd.com/read/29763446/detector-specific-correction-factors-in-radiosurgery-beams-and-their-impact-on-dose-distribution-calculations
#1
Olivia A García-Garduño, Manuel A Rodríguez-Ávila, José M Lárraga-Gutiérrez
Silicon-diode-based detectors are commonly used for the dosimetry of small radiotherapy beams due to their relatively small volumes and high sensitivity to ionizing radiation. Nevertheless, silicon-diode-based detectors tend to over-respond in small fields because of their high density relative to water. For that reason, detector-specific beam correction factors ([Formula: see text]) have been recommended not only to correct the total scatter factors but also to correct the tissue maximum and off-axis ratios...
2018: PloS One
https://www.readbyqxmd.com/read/29762136/evaluation-of-a-clinical-tof-pet-detector-design-that-achieves-%C3%A2-100-ps-coincidence-time-resolution
#2
Joshua W Cates, Craig S Levin
Commercially available clinical positron emission tomography (PET) detectors employ scintillation crystals that are long (20 mm length) and narrow (4-5 mm width) optically coupled on their narrow end to a photosensor. The aspect ratio of this traditional crystal rod conguration and 511 keV photon attenuation properties yield signicant variances in scintillation light collection efficiency and transit time to the photodetector, due to variations in the 511 keV photon interaction depth in the crystal. These variances contribute significantly to coincidence time resolution degradation...
May 15, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29762132/initial-performance-evaluation-of-a-preclinical-pet-scanner-available-as-a-clip-on-assembly-in-a-sequential-pet-mri-system
#3
Jean-Marc Vrigneaud, John McGrath, Alan Courteau, Rosie Pegg, Alberto Sanchez-Pastor Gomis, Angela Camacho, Gary Martin, Nils Schramm, François Brunotte
We evaluated the performance characteristics of a prototype preclinical PET scanner available as an easy clippable assembly that can dock to an MRI system. The single ring version of the PET system consists of 8 detectors, each of which comprises a 12 × 12 silicon photomultipliers (SiPMs) array coupled with a dual layer of offset scintillation crystals to measure depth of interaction. The crystal arrays have 29 × 29 (30 × 30 for the outer layer) 4 mm long LYSO crystals (6 mm for the outer layer). The ring diameter is 119...
May 15, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29760418/silicon-chip-based-mid-infrared-dual-comb-spectroscopy
#4
Mengjie Yu, Yoshitomo Okawachi, Austin G Griffith, Nathalie Picqué, Michal Lipson, Alexander L Gaeta
The development of a spectroscopy device on a chip that could realize real-time fingerprinting with label-free and high-throughput detection of trace molecules represents one of the big challenges in sensing. Dual-comb spectroscopy (DCS) in the mid-infrared is a powerful technique offering high acquisition rates and signal-to-noise ratios through use of only a single detector with no moving parts. Here, we present a nanophotonic silicon-on-insulator platform designed for mid-infrared (mid-IR) DCS. A single continuous-wave low-power pump source generates two mutually coherent mode-locked frequency combs spanning from 2...
May 14, 2018: Nature Communications
https://www.readbyqxmd.com/read/29737596/multifunction-interferometry-using-the-electron-mobility-visibility-and-mean-free-path-relationship
#5
N Pornsuwancharoen, P Youplao, I S Amiri, M S Aziz, Q L Tran, J Ali, P Yupapin, K T V Grattan
A conventional Michelson interferometer is modified and used to form the various types of interferometers. The basic system consists of a conventional Michelson interferometer with silicon-graphene-gold embedded between layers on the ports. When light from the monochromatic source is input into the system via the input port (silicon waveguide), the change in optical path difference (OPD) of light traveling in the stacked layers introduces the change in the optical phase, which affects to the electron mean free path within the gold layer, induces the change in the overall electron mobility can be seen by the interferometer output visibility...
May 8, 2018: Microscopy Research and Technique
https://www.readbyqxmd.com/read/29734479/task-based-design-of-a-synthetic-collimator-spect-system-used-for-small-animal-imaging
#6
Alexander Lin, Matthew A Kupinski, Todd E Peterson, Sepideh Shokouh, Lindsay C Johnson
PURPOSE: In traditional multi-pinhole SPECT systems, image multiplexing - the overlapping of pinhole projection images - may occur on the detector, which can inhibit quality image re-constructions due to photon-origin uncertainty. One proposed system to mitigate the effects of multiplexing is the synthetic-collimator SPECT system. In this system, two detectors, a silicon detector and a germanium detector, are placed at different distances behind the multi-pinhole aperture, allowing for image detection to occur at different magnifications and photon energies, resulting in higher overall sensitivity while maintaining high resolution...
May 7, 2018: Medical Physics
https://www.readbyqxmd.com/read/29727482/determination-of-the-active-volumes-of-solid-state-photon-beam-dosimetry-detectors-using-the-ptb-proton-microbeam
#7
D Poppinga, B Delfs, J Meyners, F Langner, U Giesen, D Harder, B Poppe, H K Looe
PURPOSE: 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...
May 4, 2018: Medical Physics
https://www.readbyqxmd.com/read/29716361/a-novel-flow-sensor-based-on-resonant-sensing-with-two-stage-microleverage-mechanism
#8
B Yang, X Guo, Q H Wang, C F Lu, D Hu
The design, simulation, fabrication, and experiments of a novel flow sensor based on resonant sensing with a two-stage microleverage mechanism are presented in this paper. Different from the conventional detection methods for flow sensors, two differential resonators are adopted to implement air flow rate transformation through two-stage leverage magnification. The proposed flow sensor has a high sensitivity since the adopted two-stage microleverage mechanism possesses a higher amplification factor than a single-stage microleverage mechanism...
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29715776/timing-resolution-studies-of-the-optical-part-of-the-afp-time-of-flight-detector
#9
L Chytka, G Avoni, A Brandt, E Cavallaro, P M Davis, F Förster, M Hrabovsky, Y Huang, K Jirakova, M Kocian, T Komarek, K Korcyl, J Lange, V Michalek, L Nozka, I Lopez Paz, M Rijssenbeek, P Schovanek, T Sykora, V Urbasek
We present results of the timing performance studies of the optical part and front-end electronics of the time-of-flight subdetector prototype for the ATLAS Forward Proton (AFP) detector obtained during the test campaigns at the CERN-SPS test-beam facility (120 GeV π+ particles) in July 2016 and October 2016. The time-of-flight (ToF) detector in conjunction with a 3D silicon pixel tracker will tag and measure protons originating in central exclusive interactions p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions...
April 2, 2018: Optics Express
https://www.readbyqxmd.com/read/29661973/quasi-monolithic-mirror-suspensions-in-ground-based-gravitational-wave-detectors-an-overview-and-look-to-the-future
#10
REVIEW
Anna-Maria A van Veggel
At the commencement of a new era in astrophysics, with added information from direct detections of gravitational-wave (GW) signals, this paper is a testament to the quasi-monolithic suspensions of the test masses of the GW detectors that have enabled the opening of a new window on the universe. The quasi-monolithic suspensions are the final stages in the seismic isolation of the test masses in GW detectors, and are specifically designed to introduce as little thermal noise as possible. The history of the development of the fused-silica quasi-monolithic suspensions, which have been so essential for the first detections of GWs, is outlined and a glimpse into the status of research towards quasi-monolithic suspensions made of sapphire and silicon is given...
May 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29658493/novel-inter-crystal-scattering-event-identification-method-for-pet-detectors
#11
Min Sun Lee, Seung Kwan Kang, Jae Sung Lee
Here, we proposed a novel method to identify inter-crystal scattering (ICS) events from a PET detector that is even applicable to light sharing designs. In the proposed method, the detector observation was considered as a linear problem and ICS events were identified by solving the linear problem. Three ICS identification methods were suggested to solve the linear problem 1) maximum peak detection, 2) pseudoinverse matrix calculation, and 3) convex constrained optimization. The proposed method was evaluated based on simulation and experimental studies...
April 16, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29604781/scalable-gamma-ray-camera-for-wide-area-search-based-on-silicon-photomultipliers-array
#12
Manhee Jeong, Benjamin Van, Byron T Wells, Lawrence J D'Aries, Mark D Hammig
Portable coded-aperture imaging systems based on scintillators and semiconductors have found use in a variety of radiological applications. For stand-off detection of weakly emitting materials, large volume detectors can facilitate the rapid localization of emitting materials. We describe a scalable coded-aperture imaging system based on 5.02 × 5.02 cm2 CsI(Tl) scintillator modules, each partitioned into 4 × 4 × 20 mm3 pixels that are optically coupled to 12 × 12 pixel silicon photo-multiplier (SiPM) arrays...
March 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29564367/subpixel-x-ray-imaging-with-an-energy-resolving-detector
#13
Mats Persson, Staffan Holmin, Staffan Karlsson, Hans Bornefalk, Mats Danielsson
The detector pixel size can be a severe limitation in x-ray imaging of fine details in the human body. We demonstrate a method of using spectral x-ray measurements to image the spatial distribution of the linear attenuation coefficient on a length scale smaller than one pixel, based on the fact that interfaces parallel to the x-ray beam have a unique spectral response, which distinguishes them from homogeneous materials. We evaluate the method in a simulation study by simulating projection imaging of the border of an iodine insert with [Formula: see text] in a soft tissue phantom...
January 2018: Journal of Medical Imaging
https://www.readbyqxmd.com/read/29543246/stimulated-raman-spectroscopy-of-analytes-evanescently-probed-by-a-silicon-nitride-photonic-integrated-waveguide
#14
Haolan Zhao, Stéphane Clemmen, Ali Raza, Roel Baets
We report, to the best of our knowledge, the first demonstration of stimulated Raman spectroscopy enhanced by a nanophotonic integrated circuit. The Raman response of low-concentration dimethyl sulfoxide is evanescently probed via centimeter-long wire waveguides. A signal enhancement of close to five orders of magnitude, as compared to the case of on-chip spontaneous Raman scattering, is demonstrated. This significant enhancement factor allows for the use of continuous-wave lasers with milliwatt-level power and uncooled detectors and, therefore, sets the basis of future all-on-a-chip Raman spectrometers suitable for both gas and liquid detection...
March 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29543242/mid-ir-broadband-supercontinuum-generation-from-a-suspended-silicon-waveguide
#15
Rai Kou, Taiki Hatakeyama, Jason Horng, Ji-Hun Kang, Yuan Wang, Xiang Zhang, Feng Wang
Mid-infrared light provides numerous unexpected opportunities in scientific discoveries because this wavelength region covers the fingerprints of various molecular vibrational resonances. However, the light generation efficiency and bandwidth have been a long-standing bottleneck which has limited the development so far. Moreover, the light source that can be integrated with other components such as wavelength filters, detectors, and electronics, will be the key factor toward the future practical applications...
March 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29501153/a-compact-and-low-cost-laser-induced-fluorescence-detector-with-silicon-based-photodetector-assembly-for-capillary-flow-systems
#16
Xuhui Geng, Meng Shi, Haijing Ning, Chunbo Feng, Yafeng Guan
A compact and low-cost laser induced fluorescence (LIF) detector based on confocal structure for capillary flow systems was developed and applied for analysis of Her2 protein on single Hela cells. A low-power and low-cost 450 nm laser diode (LD) instead of a high quality laser was used as excitation light source. A compact optical design together with shortened optical path length improved the optical efficiency and detection sensitivity. A superior silicon based photodetector assembly was used for fluorescence detection instead of a photomultiplier (PMT)...
May 15, 2018: Talanta
https://www.readbyqxmd.com/read/29488928/energy-dependent-dead-time-correction-in-digital-pulse-processors-applied-to-silicon-drift-detector-s-x-ray-spectra
#17
Suelen F Barros, Vito R Vanin, Alexandre A Malafronte, Nora L Maidana, Marcos N Martins
Dead-time effects in X-ray spectra taken with a digital pulse processor and a silicon drift detector were investigated when the number of events at the low-energy end of the spectrum was more than half of the total, at counting rates up to 56 kHz. It was found that dead-time losses in the spectra are energy dependent and an analytical correction for this effect, which takes into account pulse pile-up, is proposed. This and the usual models have been applied to experimental measurements, evaluating the dead-time fraction either from the calculations or using the value given by the detector acquisition system...
March 1, 2018: Journal of Synchrotron Radiation
https://www.readbyqxmd.com/read/29472075/a-novel-high-resolution-2d-silicon-array-detector-for-small-field-dosimetry-with-fff-photon-beams
#18
G Biasi, M Petasecca, S Guatelli, N Hardcastle, M Carolan, V Perevertaylo, T Kron, A B Rosenfeld
PURPOSE: Flattening filter free (FFF) beams are increasingly being considered for stereotactic radiotherapy (SRT). For the first time, the performance of a monolithic silicon array detector under 6 and 10 MV FFF beams was evaluated. The dosimeter, named "Octa" and designed by the Centre for Medical Radiation Physics (CMRP), was tested also under flattened beams for comparison. METHODS: Output factors (OFs), percentage depth-dose (PDD), dose profiles (DPs) and dose per pulse (DPP) dependence were investigated...
January 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29469886/study-on-the-inversion-of-doped-concentration-induced-by-millisecond-pulsed-laser-irradiation-silicon-based-avalanche-photodiode
#19
Dong Yuan, Wang Di, Wei Zhi, Fu Tai Ran
In this paper, an experimental study of silicon-based avalanche photodiode (Si-APD) with millisecond pulse laser irradiation was carried out, and the C-V curve of Si-APD was obtained by using a semiconductor analyzer. Based on the single-side abrupt junction character of n+p, combined with the corresponding theoretical derivation, the doping concentration varying with the axial depth of damaged Si-APD was obtained by inverse computation. The lattice dislocation and junction reduction were the fundamental causes of the reduced doping concentration...
February 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29461845/wide-spectral-photoresponse-of-layered-platinum-diselenide-based-photodiodes
#20
Chanyoung Yim, Niall McEvoy, Sarah Riazimehr, Daniel S Schneider, Farzan Gity, Scott Monaghan, Paul K Hurley, Max C Lemme, Georg S Duesberg
Platinum diselenide (PtSe2 ) is a group-10 transition metal dichalcogenide (TMD) that has unique electronic properties, in particular a semimetal-to-semiconductor transition when going from bulk to monolayer form. We report on vertical hybrid Schottky barrier diodes (SBDs) of two-dimensional (2D) PtSe2 thin films on crystalline n-type silicon. The diodes have been fabricated by transferring large-scale layered PtSe2 films, synthesized by thermally assisted conversion of predeposited Pt films at back-end-of-the-line CMOS compatible temperatures, onto SiO2 /Si substrates...
March 14, 2018: Nano Letters
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