“单光子探测器阵列”相关最新SCI收录(2)
时间: 2015-10-09   来源:   作者:   点击: 18
第 1 条,共 3 条
标题: Strategy for fitting source strength and reconstruction procedure in radioactive particle tracking
作者: Mosorov, V (Mosorov, Volodymyr)
来源出版物: APPLIED RADIATION AND ISOTOPES  卷: 103  页: 65-71  DOI: 10.1016/j.apradiso.2015.06.007  出版年: SEP 2015  
摘要: The Radioactive Particle Tracking (RPT) technique is widely applied to study the dynamic properties of flows inside a reactor. Usually, a single radioactive particle that is neutrally buoyant with respect to the phase is used as a tracker. The particle moves inside a 3D volume of interest, and its positions are determined by an array of scintillation detectors, which count the incoming photons. The particle position coordinates are calculated by using a reconstruction procedure that solves a minimization problem between the measured counts and calibration data. Although previous studies have described the influence of specified factors on the RPT resolution and sensitivities, the question of how to choose an appropriate source strength and reconstruction procedure for the given RPT setup remains an unsolved problem. This work describes and applies the original strategy for fitting both the source strength and the sampling time interval to a specified RPT setup to guarantee a required accuracy of measurements. Additionally, the measurement accuracy of an RP1' setup can be significantly increased by changing the reconstruction procedure. The results of the simulations, based on the Monte Carlo approach, have demonstrated that the proposed strategy allows for the successful implementation of the As Low As Reasonably Achievable (ALARA) principle when designing the RN' setup. The limitations and drawbacks of the proposed procedure are also presented. (C) 2015 Elsevier Ltd. All rights reserved.
入藏号: WOS:000360513900011
文献类型: Article
地址: Lodz Univ Technol, Inst Appl Comp Sci, Lodz, Poland.
通讯作者地址: Mosorov, V (通讯作者),Lodz Univ Technol, Inst Appl Comp Sci, Lodz, Poland.
电子邮件地址: volodymyr.mosorov@p.lodz.pl
ISSN: 0969-8043

第 2 条,共 3 条
标题: Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection
作者: Kontson, K (Kontson, Kimberly); Jennings, RJ (Jennings, Robert J.)
来源出版物: MEDICAL PHYSICS  卷: 42  期: 9  页: 5270-5277  DOI: 10.1118/1.4928476  出版年: SEP 2015  
摘要: Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. 
Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity, and scatter were investigated. 
Results: Analytical calculations with and without each bowtie filter show that some materials for a given design produce bowtie filters that are too large for implementation in breast CT scanners or too small to accurately manufacture. Results also demonstrate the ability to manipulate the energy fluence distribution (dynamic range) by using different materials, or different combinations of materials, for a given bowtie filter design. This feature is especially advantageous when using photon counting detector technology. Monte Carlo simulation results from PENELOPE. show that all studied material choices for bowtie design #2 achieve nearly uniform dose distribution, noise uniformity index less than 5%, and nearly uniform scatter-to-primary ratio. These same features can also be obtained using certain materials with bowtie designs #1 and #3. 
Conclusions: With the three bowtie filter designs used in this work, the selection of material is an important design consideration. An appropriate material choice can improve image quality, dose uniformity, and dynamic range. (C) 2015 American Association of Physicists in Medicine.
入藏号: WOS:000360645000027
文献类型: Article
地址: [Kontson, Kimberly] Univ Maryland, Dept Bioengn, College Pk, MD 20742 USA. 
US FDA, Div Imaging & Appl Math, Off Sci & Engn Labs, Ctr Devices & Radiol Hlth, Silver Spring, MD 20993 USA.
通讯作者地址: Kontson, K (通讯作者),Univ Maryland, Dept Bioengn, College Pk, MD 20742 USA.
电子邮件地址: Kimberly.Kontson@fda.hhs.gov
ISSN: 0094-2405

第 3 条,共 3 条
标题: Long-baseline optical intensity interferometry Laboratory demonstration of diffraction-limited imaging
作者: Dravins, D (Dravins, Dainis); Lagadec, T (Lagadec, Tiphaine); Nunez, PD (Nunez, Paul D.)
来源出版物: ASTRONOMY & ASTROPHYSICS  卷: 580  文献号: A99  DOI: 10.1051/0004-6361/201526334  出版年: AUG 2015  
摘要: Context. A long-held vision has been to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, and reveal interacting gas flows in binary systems. An opportunity is now opening up with the large telescope arrays primarily erected for measuring Cherenkov light in air induced by gamma rays. With suitable software, such telescopes could be electronically connected and also used for intensity interferometry. Second-order spatial coherence of light is obtained by cross correlating intensity fluctuations measured in different pairs of telescopes. With no optical links between them, the error budget is set by the electronic time resolution of a few nanoseconds. Corresponding light-travel distances are approximately one meter, making the method practically immune to atmospheric turbulence or optical imperfections, permitting both very long baselines and observing at short optical wavelengths. 
Aims. Previous theoretical modeling has shown that full images should be possible to retrieve from observations with such telescope arrays. This project aims at verifying diffraction-limited imaging experimentally with groups of detached and independent optical telescopes. 
Methods. In a large optics laboratory, artificial stars (single and double, round and elliptic) were observed by an array of small telescopes. Using high-speed photon-counting solid-state detectors and real-time electronics, intensity fluctuations were cross-correlated over up to 180 baselines between pairs of telescopes, producing coherence maps across the interferometric Fourier-transform plane. 
Results. These interferometric measurements were used to extract parameters about the simulated stars, and to reconstruct their two-dimensional images. As far as we are aware, these are the first diffraction-limited images obtained from an optical array only linked by electronic software, with no optical connections between the telescopes. 
Conclusions. These experiments serve to verify the concepts for long-baseline aperture synthesis in the optical, somewhat analogous to radio interferometry.
入藏号: WOS:000360020200099
文献类型: Article
地址: [Dravins, Dainis; Lagadec, Tiphaine] Lund Observ, S-22100 Lund, Sweden. 
[Nunez, Paul D.] Observ Cote Azur, Lab Lagrange, F-06304 Nice, France. 
[Nunez, Paul D.] Coll France, F-75005 Paris, France.
通讯作者地址: Dravins, D (通讯作者),Lund Observ, Box 43, S-22100 Lund, Sweden.
电子邮件地址: dainis@astro.lu.se; lagadec.tiphaine@gmail.com; paul.nunez@jpl.nasa.gov
ISSN: 0004-6361
eISSN: 1432-0746