The application of harmonic techniques to enhance resolution in mesh-based x-ray phase imaging

He, Congxiao; Sun, Weiyuan; MacDonald, Carolyn A.; Petruccelli, Jonathan C.

doi:10.1063/1.5094167

Cited by 13 publications

(11 citation statements)

References 20 publications

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“…The window in Fourier space is limited by the separation of the harmonics on detector, and the resolution of the computed image would be limited to the projected mesh period for this experiment. 18 The differential phase contrast (DPC) and dark field (DF) images can be found from the higher order harmonics. For example, the phase derivative in the vertical direction (the y axis here),…”

Section: Methodsmentioning

confidence: 99%

Dark field signal maximization in mesh-based x-ray imaging

Pyakurel

MacDonald

Petruccelli

2023

Computational Imaging VII

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Small angle x-ray scatter from microstructure too small to resolve in conventional imaging can provide an additional "dark field" signal that is complementary to attenuation and phase. Unfortunately, the low spatial coherence of clinical sources reduces dark field contrast. Focusing polycapillary optics are employed to allow for the use of high-power primary sources by increasing the phase signal after the focus. The method for this system is to structure the beam with a low-cost wire mesh that further relaxes the coherence requirement on the source. However, the coarseness of the mesh reduces the strength of the dark field signal compared with grating-based techniques, so optimization of the signal is important.

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Section: Methodsmentioning

confidence: 99%

Dark field signal maximization in mesh-based x-ray imaging

Pyakurel

MacDonald

Petruccelli

2023

Computational Imaging VII

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“…To reduce the artifacts, four images were acquired while shifting the position of the mesh by half a period. An appropriate combination of these images allows suppression of all but one of the harmonics, 36,37 as shown in Figure 4, hence suppression of the artifacts. To reduce the required dose, it is possible to use only two images to suppress the zeroth harmonic, which is the strongest harmonic and therefore the source of most artifacts when captured.…”

Section: Methodsmentioning

confidence: 99%

Phase and dark‐field imaging with mesh‐based structured illumination and polycapillary optics

et al. 2021

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Purpose: X-ray phase and dark-field (DF) imaging have been shown to improve the diagnostic capabilities of X-ray systems. However, these methods have found limited clinical use due to the need for multiple precision gratings with limited field of view or requirements on X-ray coherence that may not be easily translated to clinical practice. This work aims to develop a practicable X-ray phase and DF imaging system that could be translated and practiced in the clinic. Methods: This work employs a conventional source to create structured illumination with a simple wire mesh. A mesh-shifting algorithm is used to allow wider Fourier windowing to enhance resolution. Deconvolution of the source spot width and camera resolution improves accuracy. Polycapillary optics are employed to enhance coherence.The effects of incorporating optics with two different focal lengths are compared.Information apparent in enhanced absorption images, phase images, and DF images of fat embedded phantoms were compared and subjected to a limited receiver operator characteristic (ROC) study. The DF images of the moist and dry porous object (sponges) were compared. Results:The mesh-based phase and DF imaging system constructs images with three different information types:scatter-free absorption images,differential phase images,and scatter magnitude/DF images,simultaneously from the same original image. The polycapillary optic enhances the coherence of the beam. The deblurring technique corrects the phase signal error due to geometrical blur and the limitation of the camera modulation transfer function (MTF) and removes image artifacts to improve the resolution in a single shot. The meshshifting method allows the use of a wider Fourier processing window, which gives even higher resolution, at the expense of an increased dose. The limited ROC study confirms the efficacy of the system over the conventional system. DF images of moist and dry porous object show the significance of the system in the imaging of lung infections. Conclusion:The mesh-based X-ray phase and DF imaging system is an inexpensive and easy setup in terms of alignment and data acquisition and can produce phase and DF images in a single shot with wide field of view. The system shows significant potential for use in diagnostic imaging in a clinical setting. K E Y W O R D Simage processing, mammography, radiography, X-ray dark-field imaging, X-ray phase imaging 6642

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“…Therefore, techniques which utilize only a single image [16] are considered a more achievable way to realize quantitative phase retrieval for propagation-based phase-contrast imaging. In mesh-based x-ray phasecontrast imaging [17,18], the mesh provides an initial reference image, which can be acquired once during system calibration, and the second image used to produce object phase is obtained with both the mesh and object in the beam path so that only a single image of the object is necessary to reconstruct phase. Because of the periodicity of the mesh, differential phase contrast (DPC) images, proportional to directional first derivatives of the phase, can be achieved by windowing the mesh harmonics in the frequency domain.…”

Section: Quantitative Phase Reconstruction With a Wire Meshmentioning

confidence: 99%

“…The phase retrieval presented here relies on meshbased x-ray phase-contrast imaging [17,[19][20][21][22], illustrated in figure 1. Instead of a precision grating, a simple, low cost, coarse metallic wire mesh has been utilized to structure the beam.…”

Section: Mesh-based Propagation X-ray Phase-contrast Imagingmentioning

confidence: 99%

Grating-free quantitative phase retrieval for x-ray phase-contrast imaging with conventional sources

Sun¹,

Pyakurel²,

MacDonald³

et al. 2022

Biomed. Phys. Eng. Express

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X-ray phase-contrast imaging can display subtle differences in low-density materials (e.g. soft tissues) more readily than conventional x-ray imaging. However, producing x-ray phase images requires significant spatial coherence of the beam which in turn requires highly specialized sources such as synchrotrons, small and low power microfocus sources, or complex procedures, such as multiple exposures with several carefully stepped precision gratings. To find appropriate approaches for producing x-ray phase-contrast imaging in a clinically meaningful way, we employed a grating-free method that utilized a low-cost, coarse wire mesh and simple processing. This method relaxes the spatial coherence constraint and allows quantitative phase retrieval for not only monochromatic but also polychromatic beams. We also combined the mesh-based system with polycapillary optics to significantly improve the accuracy of quantitative phase retrieval.

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The application of harmonic techniques to enhance resolution in mesh-based x-ray phase imaging

Cited by 13 publications

References 20 publications

Dark field signal maximization in mesh-based x-ray imaging

Dark field signal maximization in mesh-based x-ray imaging

Phase and dark‐field imaging with mesh‐based structured illumination and polycapillary optics

Grating-free quantitative phase retrieval for x-ray phase-contrast imaging with conventional sources

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