Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients
ABSTRACT This page provided by the National Institute of Standards and Technology (NIST) presents tables and graphs of the photon mass attenuation coefficient and the mass energy-absorption coefficient for all of the elements Z = 1 to 92, and for 48 compounds and mixtures of radiological interest. The tables cover energies of the photon (x-ray, gamma ray, bremsstrahlung) from 1 keV to 20 MeV. The compilation is intended to be used as reference data in radiation shielding and dosimetry computations.
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- "This attenuation compares well to that provided by the iodine in conventional diagnostic x-ray applications (Miles et al 2007). The linear attenuation coefficient of the QD material is estimated to be 13 times greater than that of PFOB under the x-ray beam conditions in the study (Hubbell and Seltzer 2004, Boone et al 1997). However, at 20 μM, their concentration is very low and the dissolved QDs only displace a volume fraction of PFOB equivalent to about 7.9 × 10 −5 of a unit volume (spherical QDs assumed). "
ABSTRACT: Contrast-enhanced digital mammography (CEDM) can provide improved breast cancer detection and characterization compared to conventional mammography by imaging the effects of tumour angiogenesis. Current small-molecule contrast agents used for CEDM are limited by a short plasma half-life and rapid extravasation into tissue interstitial space. To address these limitations, nanoscale agents that can remain intravascular except at sites of tumour angiogenesis can be used. For CEDM, this agent must be both biocompatible and strongly attenuate mammographic energy x-rays. Nanoscale perfluorooctylbromide (PFOB) droplets have good x-ray attenuation and have been used in patients for other applications. However, the macroscopic scale of x-ray imaging (50-100 µm) is inadequate for direct verification that PFOB droplets localize at sites of breast tumour angiogenesis. For efficient pre-clinical optimization for CEDM, we integrated an optical marker into PFOB droplets for microscopic assessment (≪50 µm). To develop PFOB droplets as a new nanoscale mammographic contrast agent, PFOB droplets were labelled with fluorescent quantum dots (QDs). The droplets had mean diameters of 160 nm, fluoresced at 635 nm and attenuated x-ray spectra at 30.5 keV mean energy with a relative attenuation of 5.6 ± 0.3 Hounsfield units (HU) mg(-1) mL(-1) QD-PFOB. With the agent loaded into tissue phantoms, good correlation between x-ray attenuation and optical fluorescence was found (R(2) = 0.96), confirming co-localization of the QDs with PFOB for quantitative assessment using x-ray or optical methods. Furthermore, the QDs can be removed from the PFOB agent without affecting its x-ray attenuation or structural properties for expedited translation of optimized PFOB droplet formulations into patients.Physics in Medicine and Biology 07/2013; 58(15):5215-5235. DOI:10.1088/0031-9155/58/15/5215 · 2.92 Impact Factor
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- "Fitting provided by Eq. 4 to tabulated data on µ w from  "
ABSTRACT: X-ray attenuation measurements are commonly used as a non-destructive method to monitor internal concentration changes of moisture (i.e., moisture content) and other chemical compounds in porous building materials. The technique provides direct measurements of moisture content changes through analysis with a composite model consisting of a dry porous material and a thickness of water equivalent to the moisture content of the material. The current formulation of this composite model relies on certain assumptions, including a monochromatic X-ray photon beam source (i.e., X-ray photons of a single, consistent energy) and that interactions between the X-ray photons and the materials (water and porous material) are independent. However, X-ray sources typically used by researchers in this field of study produce X-ray photon beams over a spectrum of energy levels, or polychromatic X-ray photons. Implications of this inconsistency are introduced and discussed. This paper presents both an overview of fundamental descriptions of the X-ray attenuation measurement technique and results from a parametric experimental study of various porous construction materials, including calcium silicate board, aerated autoclaved concrete, clay brick, cementitious materials, and wood. Results from the parametric investigation indicate the attenuation coefficient of water is dependent on the type and thickness of the porous material.Construction and Building Materials 11/2012; 36:419–429. DOI:10.1016/j.conbuildmat.2012.04.126 · 2.27 Impact Factor
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- "above the iodine Ka edge at 33.169 keV). Data for this figure come from transformed (Zhou & Brahme, 2008) X-ray mass-attenuation coefficients (Hubbell & Seltzer, 2004). "
ABSTRACT: Leaf venation networks mediate many plant resource fluxes and are therefore of broad interest to research questions in plant physiology, systematics, paleoecology, and physics. However, the study of these networks is limited by slow and destructive imaging methods. X-ray imaging of leaf veins is potentially rapid, of high resolution, and nondestructive. Here, we have developed theory for absorption- and phase-contrast X-ray imaging. We then experimentally test these approaches using a synchrotron light source and two commercially available X-ray instruments. Using synchrotron light, we found that major veins could be consistently visualized using absorption-contrast imaging with X-ray energies < 10 keV, while both major and minor veins could be consistently visualized with the use of an iodine contrast agent at an X-ray energy of 33.269 keV. Phase-contrast imaging at a range of energies provided high resolution but highlighted individual cell walls more than veins. Both approaches allowed several hundred samples to be processed per d. Commercial X-ray instruments were able to resolve major veins and some minor veins using absorption contrast. These results show that both commercial and synchrotron X-ray imaging can be successfully applied to leaf venation networks, facilitating research in multiple fields.New Phytologist 10/2012; 196(4). DOI:10.1111/j.1469-8137.2012.04355.x · 6.55 Impact Factor