PURPOSE Presence of photon attenuation severely challenges quantitative accuracy in single-photon emission computed tomography (SPECT) imaging. Subsequently, various attenuation correction methods have been developed to compensate for this degradation. The present study aims to implement an attenuation correction method and then to evaluate quantification accuracy of attenuation correction in s...

This study examined the attenuation characteristics of five FM system sound delivery options for a group of 10 adults and 15 children (5-13 years). Sound delivery options included a tube-fitting, lightweight headphones, a CROS earmold with tubing, a CROS earmold with a snap-ring, and a standard snap-ring earmold with a vent. Attenuation was defined as the difference between probe-tube microphon...

The block medium is modeled by a discrete-periodic spatial lattice of masses connected elastic springs and viscous dampers. To describe the viscoelastic behavior interblock layers, rheological model internal friction with two Maxwell elements one Voigt element quality factor material as determining parameter proposed. Numerical experiments show that, within framework this interlayer model, it p...

In this paper, we propose a novel learning-based image restoration scheme for compressed images by suppressing compression artifacts and recovering high frequency (HF) components based upon the priors learnt from a training set of natural images. The JPEG compression process is simulated by a degradation model, represented by the signal attenuation and the Gaussian noise addition process. Based...

water quality assessment provides a scientific basis for water resources development and management. this case study proposes a factor analysis- hopfield neural network model (fhnn) based on factor analysis method and hopfield neural network method. the results showed that the factor analysis (fa) technique was introduced to identify important water quality parameters. results revealed that bio...

Background & Aims: Today, different imaging techniques have been studied in the reading of radiationsensitive polymer gels dosage. Due to limitations of imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT), ultrasound techniques are proposed for dose-dependent parameter extraction. In this study, using MAGIC-f (methacrylic and ascorbic acid in gelatin initiat...

In single photon emission computed tomography (SPECT), accurate attenuation maps are needed to perform essential attenuation compensation for high quality radioactivity estimation. Formulating the SPECT activity and attenuation reconstruction tasks as coupled signal estimation and system parameter identification problems, where the activity distribution and the attenuation parameter are treated...

Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve t...

Introduction: Nowadays, Imaging of the myocardial perfusion (MPI) using the single photon emission tomography (SPET) in the diagnosis of coronary artery disease, especially myocardial ischemia, is of great importance. In contrast to the coronary artery angiography, MPI is non-invasive, less expensive and more physiological. Unfortunately, this image is affected by the some artifacts. Thes...

For persistent infections of the mammalian host, African trypanosomes limit their population size by quorum sensing of the parasite-excreted stumpy induction factor (SIF), which induces development to the tsetse-infective stumpy stage. We found that besides this cell density-dependent mechanism, there exists a second path to the stumpy stage that is linked to antigenic variation, the main instr...