نتایج جستجو برای: phantom scatter factor

تعداد نتایج: 870740  

Journal: :Medical physics 2009
Lei Zhu Jing Wang Lei Xing

Scatter correction is crucial to the quality of reconstructed images in x-ray cone-beam computed tomography (CBCT). Most of existing scatter correction methods assume smooth scatter distributions. The high-frequency scatter noise remains in the projection images even after a perfect scatter correction. In this paper, using a clinical CBCT system and a measurement-based scatter correction, the a...

Afshin Akbarzadeh Hossein Ghadiri, Mohammad Rreza Ay, Saied Sarkar

Introduction: One of the most important parameters in x-ray CT imaging is the noise induced by detected scattered radiation. The detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. The magnitude and spatial distribution of the scattered radiation in x-ray CT should be quantified for development of robust scatter...

Journal: :Medical physics 2006
J H Siewerdsen M J Daly B Bakhtiar D J Moseley S Richard H Keller D A Jaffray

X-ray scatter poses a significant limitation to image quality in cone-beam CT (CBCT), resulting in contrast reduction, image artifacts, and lack of CT number accuracy. We report the performance of a simple scatter correction method in which scatter fluence is estimated directly in each projection from pixel values near the edge of the detector behind the collimator leaves. The algorithm operate...

2013
Xue Dong Michael Petrongolo Tianye Niu Lei Zhu

Excessive imaging dose from repeated scans and poor image quality mainly due to scatter contamination are the two bottlenecks of cone-beam CT (CBCT) imaging. Compressed sensing (CS) reconstruction algorithms show promises in recovering faithful signals from low-dose projection data but do not serve well the needs of accurate CBCT imaging if effective scatter correction is not in place. Scatter ...

Journal: :Nihon Hoshasen Gijutsu Gakkai zasshi 2012
Takahide Hayakawa Takumi Yamada Hironori Sakai Toshifumi Kasahara Tomio Inoue Michio Miyakawa

This study proposes a method to accurately estimate the phantom scatter factor (Sp) of arbitrary rectangular fields. We measured output doses in water and air; these measured values were based on square fields and a limited number of symmetric rectangular fields using 4 MV and 10 MV X-rays of a Varian Clinac-iX. We calculated Sp from these measured values. Then, using these Sp values, we estima...

2007
K. Y. T. Seet P. Blazkiewicz P. Meredith A. V. Zvyagin

An approach reported recently by Alexandrov et al. 1 on optical scatter imaging, termed digital Fourier microscopy (DFM), represents an adaptation of digital Fourier holography to selective imaging of biological matter. Holographic mode of recording of the sample optical scatter enables reconstruction of the sample image. Form-factor of the sample constituents provides a basis for discriminatio...

2016
Ching-Ching Yang

PURPOSE Scatter is a very important artifact causing factor in dental cone-beam CT (CBCT), which has a major influence on the detectability of details within images. This work aimed to improve the image quality of dental CBCT through scatter correction. METHODS Scatter was estimated in the projection domain from the low frequency component of the difference between the raw CBCT projection and...

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