Extrapolation of linear attenuation coefficients of biological materials from diagnostic-energy x-ray levels to the megavoltage range

1977 ◽  
Vol 4 (6) ◽  
pp. 505-507 ◽  
Author(s):  
William H. Payne ◽  
William D. McDavid ◽  
Robert G. Waggener ◽  
Michael J. Dennis ◽  
Victor J. Sank
Keyword(s):  
Biological Materials ◽  
Attenuation Coefficients ◽  
X Ray

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Determination of LIII subshell photoelectric parameters of iridium

2017 ◽  
Vol 95 (5) ◽  
pp. 427-431
Author(s):  
Erhan Cengiz
Keyword(s):  
Form Factor ◽  
Cross Section ◽  
Narrow Beam ◽  
Attenuation Coefficients ◽  
X Ray ◽  
Beam Geometry ◽  
Mass Attenuation Coefficients ◽  
Photoelectric Cross Section ◽  
Mass Attenuation

The LIII subshell photoelectric cross section, jump ratio, jump factor, and Davisson–Kirchner ratio of iridium have been determined by mass attenuation coefficients. The measurements have been performed using the X-ray attenuation method in narrow beam geometry. The obtained results have been compared with the tabulated values of XCOM (Berger et al. XCOM: Photon cross section database (version 1.3). NIST. Available at http://physics.nist.gov/xcom . 2005) and FFAST (Chantler et al. X-ray form factor, attenuation and scattering tables (version 2.1). NIST. Available at http://physics.nist.gov/ffast . 2005).

Electron Density and Effective Atomic Number Measurement by Using a Newly Developing Photon Counting CT System

2020 ◽  
Vol 38 ◽  
pp. 93-99
Author(s):  
Hiroshi Sakurai ◽  
Kazushi Hoshi ◽  
Yosuke Harasawa ◽  
Daiki Ono ◽  
Kun Zhang ◽  
...  
Keyword(s):  
Electron Density ◽  
Atomic Number ◽  
Photon Counting ◽  
Effective Atomic Number ◽  
Image Data ◽  
Detector Response ◽  
Simple Method ◽  
Attenuation Coefficients ◽  
X Ray ◽  
Ct System

We developed the photon counting CT system by using a conventional laboratory X-ray source and a CdTe line sensor. Attenuation coefficients were obtained from the measured CT image data. Our suggested method for deriving the electron density and effective atomic number from the measured attenuation coefficients was tested experimentally. The accuracy of the electron densities and effective atomic numbers are about <5 % (the averages of absolute values are 2.6 % and 3.1 %, respectively) for material of 6< Z and Zeff <13. Our suggested simple method, in which we do not need the exact source X-ray spectrum and detector response function, achieves comparable accuracy to the previous reports.

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