نتایج جستجو برای: inhomogeneity correction
تعداد نتایج: 170481 فیلتر نتایج به سال:
In the frame of medical imaging, accurate segmentation of brain MR images is of interest for many brain disorders. However, due to several factors such noise, imaging artifacts, intrinsic tissue variation and partial volume effects, tissue segmentation remains a challenging task. So, in this paper, a full automatic framework for segmentation of brain MR images is presented. The framework consis...
Neutron activation analysis with an internal standard correction was applied to the determination of Cr and Co in a ceramics certified reference material (NMIJ CRM 8004-a silicon nitride powder). Cesium was used as an internal standard to compensate for any inhomogeneity of the neutron flux through an irradiation capsule and to improve the repeatability of gamma-ray measurements. It was found t...
A mathematical method has been developed by which the cerebral extraction fraction of oxygen (OEF) administered in a bolus can be quantitatively measured and compared with a previously established method by Mintun et al. Successive injection of three tracers are required: 15O-labeled O2 as a test tracer, a diffusible tracer as a reference tracer and also as a flow tracer, and a tracer for cereb...
Introduction Even though echo-planar-imaging (EPI) sequence is the fastest imaging method, EPI sequences (gradient-echo (GRE) or spin-echo (SE)) have limitations in application areas due to two major artifacts, Nyquist ghost artifact and geometric distortion. In order to reduce the ghost and geometric artifacts, nonlinear phase correction methods were developed [1]. However, the nonlinear phase...
Understanding the modification of the graphene's electronic structure upon doping is crucial for enlarging its potential applications. We present a study of nitrogen-doped graphene samples on SiC(000) combining angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy (XPS). The comparison between tunneling and angle-resolved ...
Intensity Modulated Radiation Therapy (IMRT) is an innovative, three-dimensional conformal radiation treatment that can deliver highly focused and precisely shaped radiation to a tumor site through the use of the Multi-Leaf Collimators (MLC). A crucial step in IMRT procedure is the verification of MLC positioning to assure the accuracy of radiation treatment delivery. In this paper, we have dev...
Tissue intensity standardization is an important preprocessing step in the study and analysis of Magnetic Resonance Images (MRI) of human brain. Sources of variations in the intensity ranges across different MRI volumes, even after intensity inhomogeneity correction, can result from heterogeneity of data due to difference in scanners, presence of Multiple Sclerosis (MS) lesions and the stage of...
We evaluate the accuracy and precision of different techniques for measuring brain volumes based on MRI. We compare two established software packages that offer an automated image analysis, EMS and SIENAX, and a third method, which we present. The latter is based on the Interactive Watershed Transform and a model based histogram analysis. All methods are evaluated with respect to noise, image i...
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