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Single-image phase retrieval using an edge illumination X-ray phase-contrast imaging setup.

Diemoz PC, Vittoria FA, Hagen CK, Endrizzi M, Coan P, Brun E, Wagner UH, Rau C, Robinson IK, Bravin A, Olivo A - J Synchrotron Radiat (2015)

Bottom Line: Furthermore, the fact that phase information is directly extracted, instead of its derivative, can enable a simpler image interpretation and be beneficial for subsequent processing such as segmentation.Quantitative accuracy in the case of homogeneous objects as well as enhanced image quality for the imaging of complex biological samples are demonstrated through experiments at two synchrotron radiation facilities.The large range of applicability, the robustness against noise and the need for only one input image suggest a high potential for investigations in various research subjects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK.

ABSTRACT
A method is proposed which enables the retrieval of the thickness or of the projected electron density of a sample from a single input image acquired with an edge illumination phase-contrast imaging setup. The method assumes the case of a quasi-homogeneous sample, i.e. a sample with a constant ratio between the real and imaginary parts of its complex refractive index. Compared with current methods based on combining two edge illumination images acquired in different configurations of the setup, this new approach presents advantages in terms of simplicity of acquisition procedure and shorter data collection time, which are very important especially for applications such as computed tomography and dynamical imaging. Furthermore, the fact that phase information is directly extracted, instead of its derivative, can enable a simpler image interpretation and be beneficial for subsequent processing such as segmentation. The method is first theoretically derived and its conditions of applicability defined. Quantitative accuracy in the case of homogeneous objects as well as enhanced image quality for the imaging of complex biological samples are demonstrated through experiments at two synchrotron radiation facilities. The large range of applicability, the robustness against noise and the need for only one input image suggest a high potential for investigations in various research subjects.

No MeSH data available.


(a) Mixed EI image, (b) retrieved thickness and (c) corresponding vertical profile for the 500 µm PET wire. (d) Mixed EI image, (e) retrieved thickness and (f) vertical profile of thickness for the 200 µm PEEK wire.
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fig2: (a) Mixed EI image, (b) retrieved thickness and (c) corresponding vertical profile for the 500 µm PET wire. (d) Mixed EI image, (e) retrieved thickness and (f) vertical profile of thickness for the 200 µm PEEK wire.

Mentions: The ‘raw’ images containing a mixture of attenuation and refraction contrast are shown in Figs. 2 ▸(a) and 2(d). The first wire is made of polyethylene terephthalate (PET) and has a diameter of 500 µm; the second is made of polyether ether ketone (PEEK) and has a diameter of 200 µm. It can be noted that the amplitude of the FSP signal is significantly smaller than that of the EI signal, due primarily to the relatively large pixel size, which blurs the FSP signal [cf. equation (2)]. For each of the two images, equation (6) was used to retrieve the object thickness map. The following nominal values were considered in the calculation: δ = 4.09 × 10−7 and β = 7.83 × 10−11 for PET, δ = 3.92 × 10−7 and β = 6.91 × 10−11 for PEEK (Dejus & Sanchez del Rio, 1996 ▸). The retrieved thickness maps for the PET and PEEK wires are shown in Figs. 2(b) and 2(e) ▸, respectively, and the corresponding vertical profiles in Figs. 2(c) and 2(f) ▸. The expected thickness profiles are also shown for comparison: they assume perfectly cylindrical wires with a diameter equal to the nominal one provided by the supplier.


Single-image phase retrieval using an edge illumination X-ray phase-contrast imaging setup.

Diemoz PC, Vittoria FA, Hagen CK, Endrizzi M, Coan P, Brun E, Wagner UH, Rau C, Robinson IK, Bravin A, Olivo A - J Synchrotron Radiat (2015)

(a) Mixed EI image, (b) retrieved thickness and (c) corresponding vertical profile for the 500 µm PET wire. (d) Mixed EI image, (e) retrieved thickness and (f) vertical profile of thickness for the 200 µm PEEK wire.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489537&req=5

fig2: (a) Mixed EI image, (b) retrieved thickness and (c) corresponding vertical profile for the 500 µm PET wire. (d) Mixed EI image, (e) retrieved thickness and (f) vertical profile of thickness for the 200 µm PEEK wire.
Mentions: The ‘raw’ images containing a mixture of attenuation and refraction contrast are shown in Figs. 2 ▸(a) and 2(d). The first wire is made of polyethylene terephthalate (PET) and has a diameter of 500 µm; the second is made of polyether ether ketone (PEEK) and has a diameter of 200 µm. It can be noted that the amplitude of the FSP signal is significantly smaller than that of the EI signal, due primarily to the relatively large pixel size, which blurs the FSP signal [cf. equation (2)]. For each of the two images, equation (6) was used to retrieve the object thickness map. The following nominal values were considered in the calculation: δ = 4.09 × 10−7 and β = 7.83 × 10−11 for PET, δ = 3.92 × 10−7 and β = 6.91 × 10−11 for PEEK (Dejus & Sanchez del Rio, 1996 ▸). The retrieved thickness maps for the PET and PEEK wires are shown in Figs. 2(b) and 2(e) ▸, respectively, and the corresponding vertical profiles in Figs. 2(c) and 2(f) ▸. The expected thickness profiles are also shown for comparison: they assume perfectly cylindrical wires with a diameter equal to the nominal one provided by the supplier.

Bottom Line: Furthermore, the fact that phase information is directly extracted, instead of its derivative, can enable a simpler image interpretation and be beneficial for subsequent processing such as segmentation.Quantitative accuracy in the case of homogeneous objects as well as enhanced image quality for the imaging of complex biological samples are demonstrated through experiments at two synchrotron radiation facilities.The large range of applicability, the robustness against noise and the need for only one input image suggest a high potential for investigations in various research subjects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medical Physics and Biomedical Engineering, University College London, London WC1 E6BT, UK.

ABSTRACT
A method is proposed which enables the retrieval of the thickness or of the projected electron density of a sample from a single input image acquired with an edge illumination phase-contrast imaging setup. The method assumes the case of a quasi-homogeneous sample, i.e. a sample with a constant ratio between the real and imaginary parts of its complex refractive index. Compared with current methods based on combining two edge illumination images acquired in different configurations of the setup, this new approach presents advantages in terms of simplicity of acquisition procedure and shorter data collection time, which are very important especially for applications such as computed tomography and dynamical imaging. Furthermore, the fact that phase information is directly extracted, instead of its derivative, can enable a simpler image interpretation and be beneficial for subsequent processing such as segmentation. The method is first theoretically derived and its conditions of applicability defined. Quantitative accuracy in the case of homogeneous objects as well as enhanced image quality for the imaging of complex biological samples are demonstrated through experiments at two synchrotron radiation facilities. The large range of applicability, the robustness against noise and the need for only one input image suggest a high potential for investigations in various research subjects.

No MeSH data available.