Limits...
Flexible retrospective phase stepping in x-ray scatter correction and phase contrast imaging using structured illumination.

Wen H, Miao H, Bennett EE, Adamo NM, Chen L - PLoS ONE (2013)

Bottom Line: The development of phase contrast methods for diagnostic x-ray imaging is inspired by the potential of seeing the internal structures of the human body without the need to deposit any harmful radiation.However, in practical conditions the actual phase intervals can vary from step to step and also spatially.With this ability, grating-based x-ray imaging becomes more adaptable and robust for broader applications.

View Article: PubMed Central - PubMed

Affiliation: Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
The development of phase contrast methods for diagnostic x-ray imaging is inspired by the potential of seeing the internal structures of the human body without the need to deposit any harmful radiation. An efficient class of x-ray phase contrast imaging and scatter correction methods share the idea of using structured illumination in the form of a periodic fringe pattern created with gratings or grids. They measure the scatter and distortion of the x-ray wavefront through the attenuation and deformation of the fringe pattern via a phase stepping process. Phase stepping describes image acquisition at regular phase intervals by shifting a grating in uniform steps. However, in practical conditions the actual phase intervals can vary from step to step and also spatially. Particularly with the advent of electromagnetic phase stepping without physical movement of a grating, the phase intervals are dependent upon the focal plane of interest. We describe a demodulation algorithm for phase stepping at arbitrary and position-dependent (APD) phase intervals without assuming a priori knowledge of the phase steps. The algorithm retrospectively determines the spatial distribution of the phase intervals by a Fourier transform method. With this ability, grating-based x-ray imaging becomes more adaptable and robust for broader applications.

Show MeSH

Related in: MedlinePlus

Retrieved images of the head region of a mouse.The body of the mouse was fixed in formalin and then immersed in water in a plastic tube. Sagittal projections of the head and thorax area were taken. The arbitrary and position dependent phase stepping algorithm was used to analyze an electromagnetically phase stepped set of images. The results are (A) the differential phase contrast, (B) the dark-field (scatter), (C) the intensity attenuation and (D) the phase-contrast enhanced images (defined in Fig. 3). The beak-like structures in the top left are the upper and lower jaws and teeth of the mouse. The front legs can be seen below the skull. The bright rectangular object is a metallic ID tag. Phase contrast brings forth soft tissue details that are missing in the attenuation image. The scalebar in (C) is 3 mm long.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3814970&req=5

pone-0078276-g004: Retrieved images of the head region of a mouse.The body of the mouse was fixed in formalin and then immersed in water in a plastic tube. Sagittal projections of the head and thorax area were taken. The arbitrary and position dependent phase stepping algorithm was used to analyze an electromagnetically phase stepped set of images. The results are (A) the differential phase contrast, (B) the dark-field (scatter), (C) the intensity attenuation and (D) the phase-contrast enhanced images (defined in Fig. 3). The beak-like structures in the top left are the upper and lower jaws and teeth of the mouse. The front legs can be seen below the skull. The bright rectangular object is a metallic ID tag. Phase contrast brings forth soft tissue details that are missing in the attenuation image. The scalebar in (C) is 3 mm long.

Mentions: A further example of a biological application was an imaging study of a formalin fixed body of a mouse under an institutional IACUC approved protocol (C57BL/6 wild-type, 5 year old male). A sagittal projection of the head and chest region of the mouse was acquired. The three types of contrasts along with the phase-contrast enhanced image are shown in Fig. 4. The value of phase contrast lies in the enhanced high-spatial-frequency details that are visible in the differential phase contrast and the phase-contrast enhanced images but are either absent or less visible in the conventional attenuation image.


Flexible retrospective phase stepping in x-ray scatter correction and phase contrast imaging using structured illumination.

Wen H, Miao H, Bennett EE, Adamo NM, Chen L - PLoS ONE (2013)

Retrieved images of the head region of a mouse.The body of the mouse was fixed in formalin and then immersed in water in a plastic tube. Sagittal projections of the head and thorax area were taken. The arbitrary and position dependent phase stepping algorithm was used to analyze an electromagnetically phase stepped set of images. The results are (A) the differential phase contrast, (B) the dark-field (scatter), (C) the intensity attenuation and (D) the phase-contrast enhanced images (defined in Fig. 3). The beak-like structures in the top left are the upper and lower jaws and teeth of the mouse. The front legs can be seen below the skull. The bright rectangular object is a metallic ID tag. Phase contrast brings forth soft tissue details that are missing in the attenuation image. The scalebar in (C) is 3 mm long.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814970&req=5

pone-0078276-g004: Retrieved images of the head region of a mouse.The body of the mouse was fixed in formalin and then immersed in water in a plastic tube. Sagittal projections of the head and thorax area were taken. The arbitrary and position dependent phase stepping algorithm was used to analyze an electromagnetically phase stepped set of images. The results are (A) the differential phase contrast, (B) the dark-field (scatter), (C) the intensity attenuation and (D) the phase-contrast enhanced images (defined in Fig. 3). The beak-like structures in the top left are the upper and lower jaws and teeth of the mouse. The front legs can be seen below the skull. The bright rectangular object is a metallic ID tag. Phase contrast brings forth soft tissue details that are missing in the attenuation image. The scalebar in (C) is 3 mm long.
Mentions: A further example of a biological application was an imaging study of a formalin fixed body of a mouse under an institutional IACUC approved protocol (C57BL/6 wild-type, 5 year old male). A sagittal projection of the head and chest region of the mouse was acquired. The three types of contrasts along with the phase-contrast enhanced image are shown in Fig. 4. The value of phase contrast lies in the enhanced high-spatial-frequency details that are visible in the differential phase contrast and the phase-contrast enhanced images but are either absent or less visible in the conventional attenuation image.

Bottom Line: The development of phase contrast methods for diagnostic x-ray imaging is inspired by the potential of seeing the internal structures of the human body without the need to deposit any harmful radiation.However, in practical conditions the actual phase intervals can vary from step to step and also spatially.With this ability, grating-based x-ray imaging becomes more adaptable and robust for broader applications.

View Article: PubMed Central - PubMed

Affiliation: Imaging Physics Laboratory, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
The development of phase contrast methods for diagnostic x-ray imaging is inspired by the potential of seeing the internal structures of the human body without the need to deposit any harmful radiation. An efficient class of x-ray phase contrast imaging and scatter correction methods share the idea of using structured illumination in the form of a periodic fringe pattern created with gratings or grids. They measure the scatter and distortion of the x-ray wavefront through the attenuation and deformation of the fringe pattern via a phase stepping process. Phase stepping describes image acquisition at regular phase intervals by shifting a grating in uniform steps. However, in practical conditions the actual phase intervals can vary from step to step and also spatially. Particularly with the advent of electromagnetic phase stepping without physical movement of a grating, the phase intervals are dependent upon the focal plane of interest. We describe a demodulation algorithm for phase stepping at arbitrary and position-dependent (APD) phase intervals without assuming a priori knowledge of the phase steps. The algorithm retrospectively determines the spatial distribution of the phase intervals by a Fourier transform method. With this ability, grating-based x-ray imaging becomes more adaptable and robust for broader applications.

Show MeSH
Related in: MedlinePlus