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Novel x-ray attenuation mechanism: Role of interatomic distance
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10.1118/1.2975151
/content/aapm/journal/medphys/35/10/10.1118/1.2975151
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/35/10/10.1118/1.2975151

Figures

Image of FIG. 1.
FIG. 1.

The aluminum phantom has four wells capable of holding samples of solution. The three smaller empty wells were used as controls between recordings.

Image of FIG. 2.
FIG. 2.

Calibration of wells removes interwell variability. (A) Representative x-ray images from the four wells demonstrates unequal absorbance properties per well. (B) Summary data demonstrate that empty wells 2, 3, and 4 (white bars) have significantly higher absorbance values than well 1 (, ). After calculating absorbance using Beer-Lambert’s law, there were no significant (n.s.) absorbance differences of iodomethane between wells (gray bars). (C) Absorbance for each well increased linearly as the concentration of iodomethane was increased. The inset provides the linear fit parameters, demonstrating that there was no significant difference between wells.

Image of FIG. 3.
FIG. 3.

Density and the mixture rule do not always explain absorbance differences. (A) Representative images of an empty well, iodomethane , , and iododecane . (B) Summary data demonstrates that iododecane absorbance was significantly greater than absorbance (#). Iododecane and absorbance was significantly greater than absorbance of iodomethane alone . However, iodomethane is denser than and iododecane (Table II).

Image of FIG. 4.
FIG. 4.

Diiodomethane absorbance was significantly greater than the absorbance of twice the concentration of iodomethane. (A) Representative images of an empty well, diiodomethane, iodomethane, and twice the concentration of iodomethane . (B) Summary data demonstrate that iodomethane and iodomethane absorbance was significantly less than diiodomethane absorbance .

Image of FIG. 5.
FIG. 5.

Increasing x-ray energy decreases absorbance, and beam hardening increases absorbance. Diiodomethane absorbance was significantly greater than the absorbance of equimolar iodomethane (Iodomethane) and twice the concentration of iodomethane ( Iodomethane) at tube voltages of 42, 44, and 46 (, ). With beam hardening, the same was true. Additionally, beam hardening significantly increased absorbance by all three samples. The relative absorbance differences between diiodomethane, iodomethane, and iodomethane decreased as tube voltage increased.

Image of FIG. 6.
FIG. 6.

Absorbance correlates with the harmonic error at low energies and density at high energies. The molecular sketch of each compound is shown above the absorbance (white bars) and measured density (black bars) of each compound. 1,3-diiodobenzene and 2,6 diiodo-4-nitroaniline absorbance was significantly greater than other compounds. Diiodomethane absorbance was significantly less than all other compounds.

Tables

Generic image for table
TABLE I.

Beam quality.

Generic image for table
TABLE II.

Solution density for all compounds dissolved in DMSO were estimated when the compound was liquid at room temperature. N/A refers to compounds solid at room temperature where density could not be estimated. Experimental density was measured as described in Sec. II.

Generic image for table
TABLE III.

Parameters for a linear model of absorbance as a function of harmonic error and density at different beam energies without beam hardening. The model includes both energy-dependent and energy-independent relationships of absorbance to and density. Linear model: .

Generic image for table
TABLE IV.

Parameters for a linear model of absorbance as a function of harmonic error and density at different beam energies with beam hardening. The model includes both energy-dependent and energy-independent relationships of absorbance to and density. Linear model: .

Generic image for table
TABLE V.

Parameters for a linear model of absorbance as a function of harmonic error at different beam energies with beam hardening. The model includes both energy-dependent and energy-independent relationships of absorbance to . Linear model:

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/content/aapm/journal/medphys/35/10/10.1118/1.2975151
2008-09-11
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Novel x-ray attenuation mechanism: Role of interatomic distance
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/35/10/10.1118/1.2975151
10.1118/1.2975151
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