Accurate reconstruction of cross-section images from limited-angular-range data in human-limb imaging

Author(s):  
Zheng Zhang ◽  
Buxin Chen ◽  
Dan Xia ◽  
Emil Y. Sidky ◽  
Xiaochuan Pan
2021 ◽  
pp. 102030
Author(s):  
Zheng Zhang ◽  
Buxin Chen ◽  
Dan Xia ◽  
Emil Y. Sidky ◽  
Xiaochuan Pan

2021 ◽  
Vol 23 (1) ◽  
pp. 21
Author(s):  
Jelena Vukalović ◽  
Jelena B. Maljković ◽  
Francisco Blanco ◽  
Gustavo García ◽  
Branko Predojević ◽  
...  

We report the results of the measurements and calculations of the absolute differential elastic electron scattering cross-sections (DCSs) from sevoflurane molecule (C4H3F7O). The experimental absolute DCSs for elastic electron scattering were obtained for the incident electron energies from 50 eV to 300 eV, and for scattering angles from 25° to 125° using a crossed electron/target beams setup and the relative flow technique for calibration to the absolute scale. For the calculations, we have used the IAM-SCAR+I method (independent atom model (IAM) applying the screened additivity rule (SCAR) with interference terms included (I)). The molecular cross-sections were obtained from the atomic data by using the SCAR procedure, incorporating interference term corrections, by summing all the relevant atomic amplitudes, including the phase coefficients. In this approach, we obtain the molecular differential scattering cross-section (DCS), which, integrated over the scattered electron angular range, gives the integral scattering cross-section (ICS). Calculated cross-sections agree very well with experimental results, in the whole energy and angular range.


2011 ◽  
Vol 26 (03n04) ◽  
pp. 668-670
Author(s):  
◽  
PAVEL K. KURILKIN

Preliminary results on the differential cross section in dp elastic scattering has been obtained at 1.25 GeV/u with HADES within a large angular range in the center of mass system. The obtained data correspond to large transverse momenta, where a sensitivity to the 2 N and 3 N short range correlations is expected.


1980 ◽  
Vol 58 (10) ◽  
pp. 1496-1499 ◽  
Author(s):  
W. Del Bianco ◽  
G. Kajrys

The differential cross section of the 3H(p,γ)4He reaction has been measured at the proton energies Ep = 0.46, 0.50, 0.62, 0.77, and 0.93 MeV. A thin 3H–Ti target has been used and the γ-rays have been detected by a 12.7 cm diameter × 15.2 cm long NaI(Tl) crystal rotating over the angular range θL = 0 to 135°. The 3H(p,γ)4He reaction is found to proceed through E1, M1, and E2 transitions, E1 transitions being predominant. The ratio of the γ-ray flux at θL = 0 and 90° is energy dependent and decreases from 0.017 ± 0.003 at Ep = 0.46 MeV to 0.0078 ± 0.006 at Ep = 0.93 MeV.


PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1512 ◽  
Author(s):  
Matt A. White ◽  
Phil R. Bell ◽  
Alex G. Cook ◽  
Stephen F. Poropat ◽  
David A. Elliott

Megaraptorid theropods were an enigmatic group of medium-sized predatory dinosaurs, infamous for the hypertrophied claw on the first manual digit. Megaraptorid dentition is largely restricted to isolated teeth found in association with skeletal parts; however, thein situmaxillary dentition ofMegaraptorwas recently described. A newly discovered right dentary pertaining to theAustralovenatorholotype preservesin situdentition, permitting unambiguous characterisation of the dentary tooth morphology. The new jaw is virtually complete, with an overall elongate, shallow profile, and fifteen visiblein situteeth at varying stages of eruption.In situteeth confirmAustralovenatorexhibited modest pseudoheterodonty, recurved lateral teeth with a serrate distal carina and reduced mesial carina, similar to other megaraptorids.Australovenatoralso combines of figure-of-eight basal cross-section with a lanceolate shape due to the presence of labial and lingual depressions and the lingual twist of the distal carina. Computed tomography and three-dimensional imagery provided superior characterisation of the dentary morphology and enabled an accurate reconstruction to a pre-fossilised state. The newly established dental morphology also afforded re-evaluation of isolated theropod teeth discovered at theAustralovenatorholotype locality and from several additional Winton Formation localities. The isolated Winton teeth are qualitatively and quantitatively similar to thein situdentary teeth ofAustralovenator, but are also morphometrically similar to Abelisauridae, Allosauridae, Coelophysoidea, Megalosauridae and basal Tyrannosauroidea. Qualitative characters, however, clearly distinguish the teeth ofAustralovenatorand the isolated Winton teeth from all other theropods. Evidence from teeth suggests megaraptorids were the dominant predators in the Winton Formation, which contrasts with other penecontemporaneous Gondwanan ecosystems.


1992 ◽  
Vol 36 ◽  
pp. 263-271
Author(s):  
Horst Ebel ◽  
Maria F. Ebel ◽  
Robert Svagera ◽  
Martin Heller ◽  
Roland Kaitna

AbstractDepth profiling is performed by monochromatic primary excitation using variable incidence and take-off angles, A proper choice of the photon energy and the angular range of incident radiation allows depth profiling of layered structures without comparison to reference samples. The method has been verified for two different systems. Thin Al(x)Ga(1-x)As-layers on GaAs substrates are characterized by thickness D and atomic ratio x. For an excitation of AlKα-radiation by SiKα-radiation from a secondary target, the lower limit of measurement is layer thicknesses of 40 to 80 nm at x=0.6 to 0.4. Zn-coatings on steel have been investigated with CuKα radiation for selective excitation of FeKα-radiation from the substrate and with GeKα radiation for the excitation of ZnKα radiation from the layer. The scatter of the results required a measurement of the lateral homogeneity of the coating thickness. These experiments have been performed by step scanning in steps of 1 mm under fixed incidence and take-off geometry over an area of 30mm*30mm and excitation with unfiltered radiation from a Cu target diffraction tube with a beam cross section of less than 1 mm2. The obtained thickness distribution of ±20% has been confirmed by electron micrographs.


2001 ◽  
Vol 16 (16) ◽  
pp. 1027-1034 ◽  
Author(s):  
L. F. CANTO ◽  
R. DONANGELO ◽  
M. S. HUSSEIN

It is pointed out that the cross-section for the scattering of identical charged bosons is isotropic over a broad angular range around 90° when the Sommerfeld parameter has a critical value, which depends exclusively on the spin of the particle. This effect is not limited to either Coulomb scattering or bosons, and, as illustrated in the shadow scattering of identical hadrons, may lead to interesting physical effects.


Using the methods of a previous joint paper, the calculation of the scattering and polarizetion of electrons with energies between 5·4 and 1060 keV is extended to the whole angular range for the atomic field of gold. It is found that even at the highest energies the angular distribution of the scattering does not exhibit a monotonic fall with increasing angle, and that the asymmetry in double scattering reaches a maximum value which is quite large at angles greater than 90°. The variation of the total elastic cross-section with energy is also mvestigated. A simple closed formula for the scattering is obtained by transforming Dirac’s equations into a single differential equation of the same form as Schrodinger’s equation but with a modified ‘scattering potential’, and then using this potential in Born’s approximation. The resulting formula gives angular distributions to which the exact values of the scattering appear to approach more and more closely as the energy of the electrons increases. In connexion with the discrepancies between the results of various observers for the scattering and the polarization at 90°, it is shown that if a long-range repulsive field is added to the field of the atom so as appreciably to reduce the scattering, the asymmetry in double scattering is reduced by a larger factor.


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