نتایج جستجو برای: radiographic contrast

تعداد نتایج: 419377  

Journal: :Physics in medicine and biology 2015
Thibaut Frachon Loriane Weber Bernhard Hesse Simon Rit Pei Dong Cecile Olivier Françoise Peyrin Max Langer

Phase sensitive x-ray imaging expands the applicability of standard attenuation based techniques by offering several orders of magnitude of increase in sensitivity. Due to the short wavelength, x-ray phase is not directly measurable, but has to be put in evidence by the use of phase contrast techniques. The phase can then be reconstructed from one or several phase contrast images. In this study...

Journal: :Physics in medicine and biology 2006
Gocha Khelashvili Jovan G Brankov Dean Chapman Mark A Anastasio Yongyi Yang Zhong Zhong Miles N Wernick

We recently proposed a phase-sensitive x-ray imaging method called multiple-image radiography (MIR), which is an improvement on the diffraction-enhanced imaging technique. MIR simultaneously produces three images, depicting separately the effects of absorption, refraction and ultra-small-angle scattering of x-rays, and all three MIR images are virtually immune to degradation caused by scatterin...

Journal: :Medical physics 2011
Guang-Hong Chen Joseph Zambelli Ke Li Nicholas Bevins Zhihua Qi

PURPOSE The noise variance versus spatial resolution relationship in differential phase contrast (DPC) projection imaging and computed tomography (CT) are derived and compared to conventional absorption-based x-ray projection imaging and CT. METHODS The scaling law for DPC-CT is theoretically derived and subsequently validated with phantom results from an experimental Talbot-Lau interferomete...

Journal: :Medical physics 2012
Y Yue P Nguyen J Rottmann R Berbeco

PURPOSE To track prostate motion during clinical arc radiotherapy using a novel statistical motion tracking algorithm in both phantom and patient systems. METHODS For the phantom study, a dynamic phantom with a custom tumor model and radiopaque fiducials was used. For the patient study, the clinical data from two prostate patients were acquired during volumetric modulated arc therapy (VMAT). ...

2015
Hongchang Wang Sebastien Berujon Julia Herzen Robert Atwood David Laundy Alexander Hipp Kawal Sawhney

X-ray imaging techniques that capture variations in the x-ray phase can yield higher contrast images with lower x-ray dose than is possible with conventional absorption radiography. However, the extraction of phase information is often more difficult than the extraction of absorption information and requires a more sophisticated experimental arrangement. We here report a method for three-dimens...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Yunzhe Zhao Emmanuel Brun Paola Coan Zhifeng Huang Aniko Sztrókay Paul Claude Diemoz Susanne Liebhardt Alberto Mittone Sergei Gasilov Jianwei Miao Alberto Bravin

Mammography is the primary imaging tool for screening and diagnosis of human breast cancers, but ~10-20% of palpable tumors are not detectable on mammograms and only about 40% of biopsied lesions are malignant. Here we report a high-resolution, low-dose phase contrast X-ray tomographic method for 3D diagnosis of human breast cancers. By combining phase contrast X-ray imaging with an image recon...

2007
T. Tuohimaa H. M. Hertz

Phase-contrast methods increase contrast, detail, and selectivity in x-ray imaging. Present compact x-ray sources do not provide the necessary spatial coherence with sufficient power to allow the laboratory-scale high-resolution phase-contrast imaging with adequate exposure times. In this letter, the authors demonstrate phase-contrast imaging with few-micron detail employing a compact 6.5 m spo...

2006
Erik L. Ritman

Biomedical x-ray imaging has proven to be an indispensable component of many medical diagnostic and treatment techniques. Major technical advances over the years, culminating in helical scanning, multi slice, x-ray computed tomography, can now provide ∼ 0.5 mm resolution 3D images of the spatial distribution of tissue attenuation coefficients of an entire adult human thorax or abdomen. The util...

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