Development of an attenuation correction method for direct x-ray fluorescence (XRF) imaging utilizing gold L-shell XRF photons

Md Foiez Ahmed; Selcuk Yasar; Sang Hyun Cho

doi:10.1002/mp.13234

Development of an attenuation correction method for direct x-ray fluorescence (XRF) imaging utilizing gold L-shell XRF photons

Md Foiez Ahmed, Selcuk Yasar, Sang Hyun Cho

Radiation Physics

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Purpose: This work proposes a semiempirical correction method for attenuation of x-ray fluorescence (XRF) photons and/or an excitation beam during direct XRF imaging (i.e., mapping) of gold nanoparticle (GNP) distribution utilizing gold L-shell XRF photons. Methods: The current method was first devised by finding the two following relationships: (a) ratio of gold XRF peak intensity (L_α at ~9.7 keV and L_β at ~11.4 keV) vs pathlength of XRF photons; (b) XRF photon counts produced (N_xrf) vs scattered photon counts produced (N_scat). Monte Carlo simulations were performed using the Geant4 tool kit to characterize the aforementioned relationships for different tissue-like media. The applicability of the method was tested experimentally by acquiring 2D L-shell XRF images of custom-made phantoms using an experimental benchtop x-ray fluorescence computed tomography setup. Results: The results show that the ratio of gold L-shell XRF peak intensities allowed an estimation of the pathlength of XRF photons, thus can be utilized to correct for attenuation of XRF photons after emission. The results also demonstrate that N_scat, through a proportionality (Formula presented.) where the exponent T depends on the energy of scattered photons, could be used to correct for attenuation of an excitation beam prior to producing XRF photons. The corrected XRF signal was found independent of the densities of tissue-like media present along the passage of an excitation beam or emitted XRF photons. Conclusions: The current results suggest that the developed attenuation correction method plays an essential role for the detection of GNPs on the order of parts-per-million, and also for the determination of GNP concentration/location within the imaging object made of tissue-like media, without any prior knowledge of the imaging object shape, under the conditions deemed relevant to biomedical applications of gold L-shell XRF-based imaging.

Original language	English (US)
Pages (from-to)	5543-5554
Number of pages	12
Journal	Medical physics
Volume	45
Issue number	12
DOIs	https://doi.org/10.1002/mp.13234
State	Published - Dec 2018

Keywords

Geant4
Monte Carlo
attenuation correction
gold nanoparticles
x-ray fluorescence imaging

ASJC Scopus subject areas

Biophysics
Radiology Nuclear Medicine and imaging

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10.1002/mp.13234

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@article{96646811a0a247daa126ddb3acc29590,

title = "Development of an attenuation correction method for direct x-ray fluorescence (XRF) imaging utilizing gold L-shell XRF photons",

abstract = "Purpose: This work proposes a semiempirical correction method for attenuation of x-ray fluorescence (XRF) photons and/or an excitation beam during direct XRF imaging (i.e., mapping) of gold nanoparticle (GNP) distribution utilizing gold L-shell XRF photons. Methods: The current method was first devised by finding the two following relationships: (a) ratio of gold XRF peak intensity (Lα at ~9.7 keV and Lβ at ~11.4 keV) vs pathlength of XRF photons; (b) XRF photon counts produced (Nxrf) vs scattered photon counts produced (Nscat). Monte Carlo simulations were performed using the Geant4 tool kit to characterize the aforementioned relationships for different tissue-like media. The applicability of the method was tested experimentally by acquiring 2D L-shell XRF images of custom-made phantoms using an experimental benchtop x-ray fluorescence computed tomography setup. Results: The results show that the ratio of gold L-shell XRF peak intensities allowed an estimation of the pathlength of XRF photons, thus can be utilized to correct for attenuation of XRF photons after emission. The results also demonstrate that Nscat, through a proportionality (Formula presented.) where the exponent T depends on the energy of scattered photons, could be used to correct for attenuation of an excitation beam prior to producing XRF photons. The corrected XRF signal was found independent of the densities of tissue-like media present along the passage of an excitation beam or emitted XRF photons. Conclusions: The current results suggest that the developed attenuation correction method plays an essential role for the detection of GNPs on the order of parts-per-million, and also for the determination of GNP concentration/location within the imaging object made of tissue-like media, without any prior knowledge of the imaging object shape, under the conditions deemed relevant to biomedical applications of gold L-shell XRF-based imaging.",

keywords = "Geant4, Monte Carlo, attenuation correction, gold nanoparticles, x-ray fluorescence imaging",

author = "Ahmed, {Md Foiez} and Selcuk Yasar and Cho, {Sang Hyun}",

note = "Funding Information: This investigation was supported by the NIH under the award number R01EB020658 and in part by the award number R01CA155446. The content is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health. Publisher Copyright: {\textcopyright} 2018 American Association of Physicists in Medicine",

year = "2018",

month = dec,

doi = "10.1002/mp.13234",

language = "English (US)",

volume = "45",

pages = "5543--5554",

journal = "Medical physics",

issn = "0094-2405",

publisher = "AAPM - American Association of Physicists in Medicine",

number = "12",

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TY - JOUR

T1 - Development of an attenuation correction method for direct x-ray fluorescence (XRF) imaging utilizing gold L-shell XRF photons

AU - Ahmed, Md Foiez

AU - Yasar, Selcuk

AU - Cho, Sang Hyun

N1 - Funding Information: This investigation was supported by the NIH under the award number R01EB020658 and in part by the award number R01CA155446. The content is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health. Publisher Copyright: © 2018 American Association of Physicists in Medicine

PY - 2018/12

Y1 - 2018/12

N2 - Purpose: This work proposes a semiempirical correction method for attenuation of x-ray fluorescence (XRF) photons and/or an excitation beam during direct XRF imaging (i.e., mapping) of gold nanoparticle (GNP) distribution utilizing gold L-shell XRF photons. Methods: The current method was first devised by finding the two following relationships: (a) ratio of gold XRF peak intensity (Lα at ~9.7 keV and Lβ at ~11.4 keV) vs pathlength of XRF photons; (b) XRF photon counts produced (Nxrf) vs scattered photon counts produced (Nscat). Monte Carlo simulations were performed using the Geant4 tool kit to characterize the aforementioned relationships for different tissue-like media. The applicability of the method was tested experimentally by acquiring 2D L-shell XRF images of custom-made phantoms using an experimental benchtop x-ray fluorescence computed tomography setup. Results: The results show that the ratio of gold L-shell XRF peak intensities allowed an estimation of the pathlength of XRF photons, thus can be utilized to correct for attenuation of XRF photons after emission. The results also demonstrate that Nscat, through a proportionality (Formula presented.) where the exponent T depends on the energy of scattered photons, could be used to correct for attenuation of an excitation beam prior to producing XRF photons. The corrected XRF signal was found independent of the densities of tissue-like media present along the passage of an excitation beam or emitted XRF photons. Conclusions: The current results suggest that the developed attenuation correction method plays an essential role for the detection of GNPs on the order of parts-per-million, and also for the determination of GNP concentration/location within the imaging object made of tissue-like media, without any prior knowledge of the imaging object shape, under the conditions deemed relevant to biomedical applications of gold L-shell XRF-based imaging.

AB - Purpose: This work proposes a semiempirical correction method for attenuation of x-ray fluorescence (XRF) photons and/or an excitation beam during direct XRF imaging (i.e., mapping) of gold nanoparticle (GNP) distribution utilizing gold L-shell XRF photons. Methods: The current method was first devised by finding the two following relationships: (a) ratio of gold XRF peak intensity (Lα at ~9.7 keV and Lβ at ~11.4 keV) vs pathlength of XRF photons; (b) XRF photon counts produced (Nxrf) vs scattered photon counts produced (Nscat). Monte Carlo simulations were performed using the Geant4 tool kit to characterize the aforementioned relationships for different tissue-like media. The applicability of the method was tested experimentally by acquiring 2D L-shell XRF images of custom-made phantoms using an experimental benchtop x-ray fluorescence computed tomography setup. Results: The results show that the ratio of gold L-shell XRF peak intensities allowed an estimation of the pathlength of XRF photons, thus can be utilized to correct for attenuation of XRF photons after emission. The results also demonstrate that Nscat, through a proportionality (Formula presented.) where the exponent T depends on the energy of scattered photons, could be used to correct for attenuation of an excitation beam prior to producing XRF photons. The corrected XRF signal was found independent of the densities of tissue-like media present along the passage of an excitation beam or emitted XRF photons. Conclusions: The current results suggest that the developed attenuation correction method plays an essential role for the detection of GNPs on the order of parts-per-million, and also for the determination of GNP concentration/location within the imaging object made of tissue-like media, without any prior knowledge of the imaging object shape, under the conditions deemed relevant to biomedical applications of gold L-shell XRF-based imaging.

KW - Geant4

KW - Monte Carlo

KW - attenuation correction

KW - gold nanoparticles

KW - x-ray fluorescence imaging

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JF - Medical physics

IS - 12

ER -

Development of an attenuation correction method for direct x-ray fluorescence (XRF) imaging utilizing gold L-shell XRF photons

Abstract

Keywords

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