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Winkelmann A, Nolze G, Cios G, Tokarski T, Bała P, Hourahine B, Trager-Cowan C. Kikuchi pattern simulations of backscattered and transmitted electrons. J Microsc 2021; 284:157-184. [PMID: 34275156 DOI: 10.1111/jmi.13051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/15/2021] [Indexed: 11/29/2022]
Abstract
We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness- and energy-dependent features which are observed in experimental Kikuchi diffraction patterns. Excess-deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two-beam approximation to dynamical electron diffraction, a phenomenological model of excess-deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre-calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKD can be affected by changes in the order of 10 - 3 - 10 - 2 if excess-deficiency features are not considered in the theoretical model underlying a best-fit pattern matching approach. Correspondingly, the absolute accuracy of simulation-based EBSD strain determination can suffer from biases of a similar order of magnitude if excess-deficiency effects are neglected in the simulation model.
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Affiliation(s)
- Aimo Winkelmann
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Kraków, Poland.,Department of Physics, SUPA, University of Strathclyde, Glasgow, UK
| | - Gert Nolze
- Federal Institute for Materials, Research and Testing (BAM), Berlin, Germany.,TU Bergakademie Freiberg, Institute for Mineralogy, Freiberg, Germany
| | - Grzegorz Cios
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Kraków, Poland
| | - Tomasz Tokarski
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Kraków, Poland
| | - Piotr Bała
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Kraków, Poland
| | - Ben Hourahine
- Department of Physics, SUPA, University of Strathclyde, Glasgow, UK
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Craven AJ, Valdreè U. Visibility Of Diffraction Patterns And Bend Contours In Thick Composite Amorphous-Crystalline Specimens Observed In Stem And Ctem. J Microsc 2011. [DOI: 10.1111/j.1365-2818.1979.tb00173.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Fourkal E, Li JS, Ding M, Tajima T, Ma CM. Particle selection for laser-accelerated proton therapy feasibility study. Med Phys 2003; 30:1660-70. [PMID: 12906183 DOI: 10.1118/1.1586268] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In this paper we present calculations for the design of a particle selection system for laser-accelerated proton therapy. Laser-accelerated protons coming from a thin high-density foil have broad energy and angular spectra leading to dose distributions that cannot be directly used for therapeutic applications. Our solution to this problem is a compact particle selection and collimation device that delivers small pencil beams of protons with desired energy spectra. We propose a spectrometer-like particle selection and beam modulation system in which the magnetic field will be used to spread the protons spatially according to their energies and emitting angles. Subsequently, an aperture will be used to select the protons within a therapeutic window of energy (energy modulation). It will be shown that for the effective proton spatial differentiation, the primary collimation device should be used, which will collimate protons to the desired angular distribution and limit the spatial mixing of different energy protons once they have traveled through the magnetic system. Due to the angular proton distribution, the spatial mixing of protons of different energies will always be present and it will result in a proton energy spread with the width depending on the energy. For 250 MeV protons, the width (from the maximum to the minimum energy) is found to be 50 MeV for the magnetic field configuration used in our calculations. As the proton energy decreases, its energy width decreases as well, and for 80 MeV protons it equals 9 MeV. The presence of the energy width in the proton energy distribution will modify the depth dose curves needed for the energy modulation calculation. The matching magnetic field setup will ensure the refocusing of the selected protons and the final beam will be collimated by the secondary collimator. The calculations presented in this article show that the dose rate that the selection system can yield is on the order of D=260 Gy/min for a field size of 1 x 1 cm2.
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Affiliation(s)
- E Fourkal
- Radiation Oncology Department, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
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Fourkal E, Shahine B, Ding M, Li JS, Tajima T, Ma CM. Particle in cell simulation of laser-accelerated proton beams for radiation therapy. Med Phys 2002; 29:2788-98. [PMID: 12512712 DOI: 10.1118/1.1521122] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In this article we present the results of particle in cell (PIC) simulations of laser plasma interaction for proton acceleration for radiation therapy treatments. We show that under optimal interaction conditions protons can be accelerated up to relativistic energies of 300 MeV by a petawatt laser field. The proton acceleration is due to the dragging Coulomb force arising from charge separation induced by the ponderomotive pressure (light pressure) of high-intensity laser. The proton energy and phase space distribution functions obtained from the PIC simulations are used in the calculations of dose distributions using the GEANT Monte Carlo simulation code. Because of the broad energy and angular spectra of the protons, a compact particle selection and beam collimation system will be needed to generate small beams of polyenergetic protons for intensity modulated proton therapy.
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Affiliation(s)
- E Fourkal
- Radiation Oncology Department, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
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Sauer OA. Dosisverteilungen an Material-Grenzflächen bei energiereichen Röntgenstrahlen* *Dieser Artikel enthält Teile einer bei der Fakultät für Physik und Astronomie der Universität Würzburg eingereichten Dissertation. Z Med Phys 1995. [DOI: 10.1016/s0939-3889(15)70600-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Marthinsen K, Holmestad R, Høier R. Analytical filtering of low-angle inelastic scattering contributions toCBED contrast. Ultramicroscopy 1994. [DOI: 10.1016/0304-3991(94)90061-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Backe H, Gampert S, Grendel A, Hartmann HJ, Lauth W, Weinheimer C, Zahn R, Buskirk FR, Euteneuer H, Kaiser KH, Stephan G, Walcher T. Resonant transition radiation in the X-ray region from a low emittance 855 MeV electron beam. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf01296337] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Su DS, Zeitler E. Background problem in electron-energy-loss spectroscopy. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:14734-14740. [PMID: 10005846 DOI: 10.1103/physrevb.47.14734] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Reimer L, Rennekamp R, Fromm I, Langenfeld M. Contrast in the electron spectroscopic imaging mode of a TEM. IV. Thick specimens imaged by the most-probable energy loss. J Microsc 1991; 162:3-14. [PMID: 1870112 DOI: 10.1111/j.1365-2818.1991.tb03111.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
When the zero-loss transmission falls below 10(-3) for biological sections of mass-thickness greater than 70 micrograms/cm2, the energy window in the electron spectroscopic imaging (ESI) mode of an energy-filtering electron microscope (EFEM) can be shifted to the most-probable energy loss of the electron energy-loss spectrum. This enables mass-thicknesses up to 150 micrograms/cm2 or thicknesses of 1.5 microns to be examined. Electron energy-loss spectra of thick carbon films calculated by a Fourier method agree with experimental spectra. Measurements of the electron energy-loss spectroscopy and ESI image intensities with an additional platinum film confirm a scattering model for the calculation of the image intensity. This model considers the angular broadening at the most-probable energy loss by introducing an effective illumination aperture of the order of the full-width at half-maximum of the angular distribution.
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Affiliation(s)
- L Reimer
- Physikalisches Institut, Universität Münster, Germany
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Monte Carlo calculations of elastic and inelastic electron scattering in biological and plastic materials. Ultramicroscopy 1984. [DOI: 10.1016/0304-3991(84)90206-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Varley B, Kitching J, Leo W, Miskin J, Moore R, Wunsch K, Decker R, Wollnik H, Siegert G. Investigations of the response of germanium detectors to monoenergetic electron, positron and gamma ray beams. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/0029-554x(81)90955-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lauterwasser BD, Kramer EJ. Microscopic mechanisms and mechanics of craze growth and fracture. ACTA ACUST UNITED AC 1979. [DOI: 10.1080/01418617908239285] [Citation(s) in RCA: 206] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Measurement of the absolute cross section for the elementary process of atomic field bremsstrahlung. ACTA ACUST UNITED AC 1977. [DOI: 10.1007/bf01408838] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Lamvik MK, Groves T. Minimization of dose as a criterion for the selection of imaging modes in electron microscopy of amorphous specimens. Ultramicroscopy 1976; 2:69-75. [PMID: 1028210 DOI: 10.1016/s0304-3991(76)90467-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A fundamental limitation in electron microscopy of organic specimens is radiation damage by the electron beam. To minimize damage it is necessary to have maximum information collection for a given dose. Various modes of operation of conventional and scanning transmission microscopes are compared with respect to their ability to detect small changes in specimen thickness or density with a given signal to noise ratio. Incoherent imaging is assumed, and this is expected to apply to amorphous specimens under a variety of microscope conditions. For either very thin or very thick specimens, the scanning transmission microscope is found to require nearly 10 times less dose than a conventional microscope for the same signal to noise ratio in the image. For specimens of intermediate thickness, scanning and conventional transmission electron microscopes are roughly equivalent.
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Absolute electron impactK-ionization cross sections of titanium and nickel (?50 keV). ACTA ACUST UNITED AC 1975. [DOI: 10.1007/bf01434021] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
A theory of resolution and image formation is presented for thick amorphous specimens in transmission electron microscopes. Eight modes of operation are considered, four in the scanning transmission electron microscope (STEM) and four in the conventional electron microscope (CEM). A thick specimen is defined here as one in which the resolution of detail is limited by plural scattering of the electron beam. In practice this includes films on the order of a micron in thickness. An analytic theory of plural incoherent scattering is developed which is general with respect to material and beam voltage. The theory gives the distribution of elastically scattered electrons as a function of transverse coordinate and angles, and is directly applicable to optical systems. The theory applies to all thicknesses normally encountered, and includes thin specimens as well as thick specimens. Criteria are proposed for evaluation of the quality of microscope images, and the modulation transfer function is applied to determine some practical estimates of picture quality. The STEM is found to have distinct advantages over the CEM for thick specimens. For a carbon specimen one micron thick a STEM operating in bright field at 90 keV produces an image which is roughly equivalent to that of a CEM operating in bright field at 1 MeV. Improvement can be obtained in the CEM by filtering out eneryg-loss electrons which degrade resolution due to chromatic aberration. This results in a reduction in signal intensity and usable thickness, however.
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Finger U, Gärtner K, Koch HD, Trippensee W. Computer program for the calculation of radiation damage distribution from the energy spectrum of backscattered ions. J Radioanal Nucl Chem 1975. [DOI: 10.1007/bf02516862] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Eisen FH, Welch B. Flux and fluence dependence of disorder produced during implantation of11B in silicon. ACTA ACUST UNITED AC 1971. [DOI: 10.1080/00337577108232575] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Chadderton LT, Eisen FH. On the annealing of damage produced by boron ion implantation of silicon single crystals. ACTA ACUST UNITED AC 1971. [DOI: 10.1080/00337577108232573] [Citation(s) in RCA: 50] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Oms J, Chédin P. L'effet photoélectrique à 279 keV dans le plomb : distribution angulaire et diffusion des photoélectrons k. ACTA ACUST UNITED AC 1967. [DOI: 10.1051/jphys:01967002803-4028100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Marton L, Simpson JA, Fowler HA, Swanson N. Plural Scattering of 20-kev Electrons in Aluminum. ACTA ACUST UNITED AC 1962. [DOI: 10.1103/physrev.126.182] [Citation(s) in RCA: 83] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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