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Silicon detector

Alexander M Grant, Brian J Lee, Chen-Ming Chang, Craig S Levin
PURPOSE: A brain sized radio frequency (RF)-penetrable PET insert has been designed for simultaneous operation with MRI systems. This system takes advantage of electro-optical coupling and battery power to electrically float the PET insert relative to the MRI ground, permitting RF signals to be transmitted through small gaps between the modules that form the PET ring. This design facilitates the use of the built-in body coil for RF transmission and thus could be inserted into any existing MR site wishing to achieve simultaneous PET/MR imaging...
January 2017: Medical Physics
J Martínez Ortega, N Gómez González, P Castro Tejero, M Pinto Monedero, N B Tolani, L Núñez Martín, R Sánchez Montero
PURPOSE: Amorphous silicon electronical portal imaging devices (EPIDs) are widely used for dosimetric measurements in Radiation Therapy. The purpose of this work was to determine if a portal dose prediction method can be utilized for dose map calculations based on the linear accelerator model within a commercial treatment planning system (Pinnacle(3) v8.0 m). METHODS: The method was developed for a 6 MV photon beam on the Varian Clinac 21-EX, at a nominal dose rate of 400 MU/min...
January 2017: Medical Physics
Rhys M Preston, James R Tickner
With the rise of the Silicon Photomultiplier (SiPM), it is now practical to build compact scintillation detectors well suited to portable use. A prototype survey meter for fast-neutrons and gamma-rays, based around an EJ-299-34 plastic scintillator with SiPM readout, has been developed and tested. A custom digital pulse processor was used to perform pulse shape discrimination on-the-fly. Ambient dose equivalent H*(10) was calculated by means of two energy-dependent 'G-functions'. The sensitivity was calculated to be between 0...
January 17, 2017: Radiation Protection Dosimetry
Guen Bae Ko, Jae Sung Lee
We propose a novel single transmission-line readout method for whole-body time-of-flight positron emission tomography applications, without compromising on performance. The basic idea of the proposed multiplexing method is the addition of a specially prepared tag signal ahead of the scintillation pulse. The tag signal is a square pulse that encodes photon arrival time and channel information. The two-dimensional position of a silicon photomultiplier (SiPM) array is encoded by the specific width and height of the tag signal...
January 18, 2017: Physics in Medicine and Biology
Alexander V Stolin, Peter F Martone, Gangadhar Jaliparthi, Raymond R Raylman
Positron emission tomography (PET) scanners designed for imaging of small animals have transformed translational research by reducing the necessity to invasively monitor physiology and disease progression. Virtually all of these scanners are based on the use of pixelated detector modules arranged in rings. This design, while generally successful, has some limitations. Specifically, use of discrete detector modules to construct PET scanners reduces detection sensitivity and can introduce artifacts in reconstructed images, requiring the use of correction methods...
January 2017: Journal of Medical Imaging
Valentina Giacometti, Vladimir A Bashkirov, Pierluigi Piersimoni, Susanna Guatelli, Tia E Plautz, Hartmut F-W Sadrozinski, Robert P Johnson, Andriy Zatserklyaniy, Thomas Tessonnier, Katia Parodi, Anatoly B Rosenfeld, Reinhard W Schulte
PURPOSE: Proton computed tomography (pCT) is a promising imaging technique to substitute or at least complement x-ray CT for more accurate proton therapy treatment planning as it allows calculating directly proton relative stopping power from proton energy loss measurements. A proton CT scanner with a silicon-based particle tracking system and a 5 stage scintillating energy detector has been completed. In parallel a modular software platform was developed to characterize the performance of the proposed pCT...
January 17, 2017: Medical Physics
Chumin Zhao, Nikita Vassiljev, Anastasios Konstantinidis, Robert Speller, Jerzy Kanicki
High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 ��m pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30��...
January 10, 2017: Physics in Medicine and Biology
Dongdong Dong, Hui Deng, Chao Hu, Huaibing Song, Keke Qiao, Xiaokun Yang, Jian Zhang, Fensha Cai, Jiang Tang, Haisheng Song
To date, all the lead halide based full-inorganic or organic-inorganic hybrid perovskites have been synthesized from organic solvent, such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), by a solution method. Herein, water has been utilized as a 'green' solvent to develop an efficient synthetic route to grow various kinds of lead halide perovskite nanowires (NWs). By controlling the proportion of the hybrid cations, Csx(CH3NH3)1-xPbI3 perovskite NWs were successfully synthesized. Every Csx(CH3NH3)1-xPbI3 perovskite NW demonstrated single crystal characteristics with uniform stoichiometric element distribution...
January 9, 2017: Nanoscale
Guangwei Cong, Morifumi Ohno, Yuriko Maegami, Makoto Okano, Koji Yamada
Optical autocorrelation accuracy was for the first time analyzed for the silicon waveguide based autocorrelators utilizing two-photon absorption (TPA) under various short pulse conditions by numerical simulation. As for autocorrelation operation in the sub-μm silicon p-i-n rib waveguides on the 220 nm SOI (silicon on insulator) wafers, the autocorrelation error of pulse width measurement gradually increases with the increase of the peak power for both Gaussian and hyperbolic secant pulses due to the influence of free-carrier absorption (FCA)...
December 26, 2016: Optics Express
Rui Li, Lingyan Du, Fei Tang, Yadong Jiang, Zhiming Wu
Microstructured Te-doped silicon is prepared via a femtosecond laser irradiating Si coated with Si-Te bilayer films, and photodiodes are successfully fabricated from this material. The samples are thermally annealed at 773 K for three different time durations. The effects of annealing time on microstructures, infrared absorptance, and photosensitivity of Te-doped silicon are investigated. From the scanning electronic microscope images and the optical absorptance spectra, the results show that the infrared absorptance decreases with the increase of annealing time durations, while the infrared photoresponse follows an opposite tendency...
December 20, 2016: Applied Optics
Maria Navas-Moreno, James W Chan
We demonstrate the compatibility of a Hadamard-coded multifocal array approach with a 1064 nm dispersive Raman microscope for improving the imaging speed. The system uses a galvomirror to generate a one-dimensional (1-D) multifocal array at the sample, and the Raman signals from the multiple foci are simultaneously detected by an InGaAs linear detector array. The superimposed spectra are deconvolved to retrieve the individual spectra at each focus. Using a silicon wafer as a test sample, we demonstrate that the method is ideal for the high noise detection conditions encountered when using 1064 nm excitation, InGaAs detectors, and high readout rates...
January 1, 2017: Optics Letters
Tia E Plautz, R P Johnson, H F-W Sadrozinski, A Zatserklyaniy, V Bashkirov, R F Hurley, R W Schulte, P Piersimoni, V Giacometti
PURPOSE: To characterize the modulation transfer function (MTF) of the pre-clinical (phase II) head scanner developed for proton computed tomography (pCT) by the pCT collaboration. To evaluate the spatial resolution achievable by this system. METHODS: Our phase II proton CT scanner prototype consists of two silicon telescopes that track individual protons upstream and downstream from a phantom, and a 5-stage scintillation detector that measures a combination of the residual energy and range of the proton...
June 2016: Medical Physics
A K Liang, M Koniczek, L E Antonuk, Y El-Mohri, Q Zhao
PURPOSE: Photon counting arrays (PCAs) offer several advantages over conventional, fluence-integrating x-ray imagers, such as improved contrast by means of energy windowing. For that reason, we are exploring the feasibility and performance of PCA pixel circuitry based on polycrystalline silicon. This material, unlike the crystalline silicon commonly used in photon counting detectors, lends itself toward the economic manufacture of radiation tolerant, monolithic large area (e.g., ∼43×43 cm2) devices...
June 2016: Medical Physics
A Syme, H Lin, J Rubio-Sanchez, D Perepichka
PURPOSE: To fabricate organic field effect transistors (OFETs) and evaluate their performance before and after exposure to ionizing radiation. To determine if OFETs have potential to function as radiation dosimeters. METHODS: OFETs were fabricated on both Si/SiO2 wafers and flexible polymer substrates using standard processing techniques. Pentacene was used as the organic semiconductor material and the devices were fabricated in a bottom gate configuration. Devices were irradiated using an orthovoltage treatment unit (120 kVp x-rays)...
June 2016: Medical Physics
M Bach, J Wulff
PURPOSE: Interference of dose application in scanned beam particle therapy and organ motion may lead to interplay effects with distorted dose to target volumes. Interplay effects depend on the speed and direction of the scanning beam, leading to fringed field edges (scanning parallel to organ motion direction) or over- and under-dosed regions (both directions are orthogonal). Current repainting methods can mitigate interplay effects, but are susceptible to artefacts when only a limited number of repaints are applied...
June 2016: Medical Physics
E Izaguirre, S Pokhrel, S Hedrick, T Knewtson
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...
June 2016: Medical Physics
Q Cao, M Brehler, A Sisniega, E Marinetto, A Zyazin, I Peters, J Stayman, J Yorkston, J Siewerdsen, W Zbijewski
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...
June 2016: Medical Physics
B Han, L Xing, L Wang
PURPOSE: To systematically investigate an ultra-high spatial-resolution amorphous silicon flat-panel electronic portal imaging device (EPID) for MLC-based full-body robotic radiosurgery geometric and dosimetric quality assurance (QA). METHODS: The high frame-rate and ultra-high spatial resolution EPID is an outstanding detector for measuring profiles, MLC-shaped radiosurgery field aperture verification, and small field dosimetry. A Monte Carlo based technique with a robotic linac specific response and calibration is developed to convert a raw EPID-measured image of a radiosurgery field into water-based dose distribution...
June 2016: Medical Physics
D Vernekohl, M Ahmad, G Chinn, L Xing
PURPOSE: The application of Compton cameras (CC) is a novel approach translating XFCT to a practical modality realized with clinical CT systems without the restriction of pencil beams. The dual modality design offers additional information without extra patient dose. The purpose of this work is to investigate the feasibility and efficacy of using CCs for volumetric x-ray fluorescence (XF) imaging by Monte Carlo (MC) simulations and statistical image reconstruction. METHODS: The feasibility of a CC for imaging x-ray fluorescence emitted from targeted lesions is examined by MC simulations...
June 2016: Medical Physics
P Wang, J Cammin, F Bisello, T Solberg, J McDonough, T Zhu, D Menichelli, B Teo
PURPOSE: Proton radiography and proton computed tomography (PCT) can be used to measure proton stopping power directly. However, practical and cost effective proton imaging detectors are not widely available. In this study, the authors investigated the feasibility of proton imaging using a silicon diode array. METHODS: A one-dimensional silicon-diode detector array (1DSDA) was aligned with the central axis (CAX) of the proton beam. Polymethyl methacrylate (PMMA) slabs were used to find the correspondence between the water equivalent thickness (WET) and 1DSDA channel number...
June 2016: Medical Physics
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