Effects of signal diffusion on x-ray phase contrast images

Ignatyev, K.; Munro, P. R. T.; Speller, R. D.; Olivo, A.
July 2011
Review of Scientific Instruments;Jul2011, Vol. 82 Issue 7, p073702
Academic Journal
We discuss the problem of signal diffusion among neighbouring pixels in x-ray phase contrast imaging (XPCi) specifically for coded-aperture (CA) XPCi, but many of the discussed observations are directly transferable to other XPCi modalities. CA XPCi exploits the principle of pixel edge illumination by means of two CA masks. The first mask, placed in contact with the detector, creates insensitive regions between adjacent pixels; the second one, placed immediately before the sample, creates individual beams impinging on the boundaries between sensitive and insensitive regions on the detector, as created by the detector mask. In this way, edge illumination is achieved for all pixels of an area detector illuminated by a divergent and polychromatic beam generated by a conventional source. As the detector mask redefines the resolution properties of the detector, sample dithering can be used to effectively increase the system spatial resolution, without having to apply any post-processing procedure (e.g., deconvolution). This however creates artifacts in the form of secondary fringes (which have nothing to do with phase-related secondary fringes) if there is signal diffusion between adjacent pixels. In non-dithered images, signal diffusion between adjacent pixels causes a reduction in image contrast. This effect is investigated both theoretically and experimentally, and its direct implications on image quality are discussed. The interplay with the sample positioning with respect to the detector pixel matrix, which also has an effect on the obtained image contrast, is also discussed.


Related Articles

  • Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose gadopentetate dimeglumine. Woodard, Pamela; Chenevert, Thomas; Dirk Sostman, H.; Jablonski, Kathleen; Stein, Paul; Goodman, Lawrence; Londy, Frank; Narra, Vamsidhar; Hales, Charles; Hull, Russell; Tapson, Victor; Weg, John // International Journal of Cardiovascular Imaging;Feb2012, Vol. 28 Issue 2, p295 

    During a recent multi-center trial assessing gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE), the Food and Drug Administration announced a risk of nephrogenic sclerosing fibrosis in patients with renal insufficiency who had received...

  • Voiding urosonography including urethrosonography: high-quality examinations with an optimised procedure using a second-generation US contrast agent. Duran, Carmina; Riego, Javier; Riera, Luis; Martin, Cesar; Serrano, Carlos; PalaƱa, Pau // Pediatric Radiology;Jun2012, Vol. 42 Issue 6, p660 

    Background: Voiding urosonography (VUS) is established as a technique for detecting vesicoureteral reflux in children. Objective: To evaluate the quality of images of the entire urinary tract when using a second-generation US contrast agent and a modified VUS technique. Materials and methods: We...

  • Novel contrast-injection protocol for coronary computed tomographic angiography: contrast-injection protocol customized according to the patient's time-attenuation response. Kidoh, Masafumi; Nakaura, Takeshi; Nakamura, Shinichi; Awai, Kazuo; Utsunomiya, Daisuke; Namimoto, Tomohiro; Harada, Kazunori; Yamashita, Yasuyuki // Heart & Vessels;Mar2014, Vol. 29 Issue 2, p149 

    We developed a new individually customized contrast-injection protocol for coronary computed tomography (CT) angiography based on the time-attenuation response in a test bolus, and investigated its clinical applicability. We scanned 60 patients with suspected coronary diseases using a...

  • Improving Diagnostic Viewing of Medical Images using Enhancement Algorithms. Ahmed, Hanan Saleh S.; Nordin, Jan // Journal of Computer Science;2011, Vol. 7 Issue 12, p1831 

    Problem statement: Various images are low quality and difficultly to detect and extract information. Therefore, the image has to get under a process called image enhancement which contains an aggregation of techniques that look for improving the visual aspect of an image. Medical images are one...

  • Synthetic MRI of the brain in a clinical setting. Blystad, I.; Warntjes, J. B. M.; Smedby, O.; Landtblom, A.-M.; Lundberg, P.; Larsson, E.-M. // Acta Radiologica;Dec2012, Vol. 53 Issue 10, p1158 

    Background: Conventional magnetic resonance imaging (MRI) has relatively long scan times for routine examinations, and the signal intensity of the images is related to the specific MR scanner settings. Due to scanner imperfections and automatic optimizations, it is impossible to compare images...

  • Intraindividual comparison of myocardial delayed enhancement MR imaging using gadobenate dimeglumine at 1.5 T and 3 T. Klumpp, Bernhard D.; Sandstede, Joern; Lodemann, Klaus P.; Seeger, Achim; Hoevelborn, Tobias; Fenchel, Michael; Kramer, Ulrich; Claussen, Claus D.; Miller, Stephan // European Radiology;May2009, Vol. 19 Issue 5, p1124 

    For contrast-enhanced imaging techniques relying on strong T1 weighting, 3 T provides increased contrast compared with 1.5 T. The aim of our study was the intraindividual comparison of delayed enhancement MR imaging at 1.5 T and at 3 T. Twenty patients with myocardial infarction were examined at...

  • PET/CT in lung cancer: Influence of contrast medium on quantitative and clinical assessment. Behrendt, Florian; Temur, Yavuz; Verburg, Frederik; Palmowski, Moritz; Krohn, Thomas; Pietsch, Hubertus; Kuhl, Christiane; Mottaghy, Felix // European Radiology;Nov2012, Vol. 22 Issue 11, p2458 

    Objectives: To evaluate the influence of intravenous contrast medium and different contrast medium phases on attenuation correction, PET image quality and clinical staging in combined PET/CT in patients with a suspicion of lung cancer. Methods: Sixty patients with a suspicion of lung cancer were...

  • X-ray phase contrast tomography; proof of principle for post-mortem imaging. ZAMIR, ANNA; ARTHURS, OWEN J.; HAGEN, CHARLOTTE K.; DIEMOZ, PAUL C.; BROCHARD, THIERRY; BRAVIN, ALBERTO; SEBIRE, NEIL J.; OLIVO, ALESSANDRO // British Journal of Radiology;Feb2016, Vol. 89 Issue 1058, p1 

    Objective: To demonstrate the feasibility of using X-ray phase-contrast tomography to assess internal organs in a post-mortem piglet model, as a possible non-invasive imaging autopsy technique. Methods: Tomographic images of a new-born piglet were obtained using a free-space propagation X-ray...

  • Image Quality Assessment Based on Inter-Patch and Intra-Patch Similarity. Zhou, Fei; Lu, Zongqing; Wang, Can; Sun, Wen; Xia, Shu-Tao; Liao, Qingmin // PLoS ONE;Mar2015, Vol. 10 Issue 3, p1 

    In this paper, we propose a full-reference (FR) image quality assessment (IQA) scheme, which evaluates image fidelity from two aspects: the inter-patch similarity and the intra-patch similarity. The scheme is performed in a patch-wise fashion so that a quality map can be obtained. On one hand,...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics