Photon attenuation in tissues is the primary physical degrading factor limiting both visual qualitative interpretation and quantitative analysis capabilities of reconstructed Positron Emission Tomography (PET) images. This study investigates the implementation and applicability of transmission atlas-guided attenuation correction in cerebral 3D PET imaging, thus eliminating the need for acquisit...

The electrical properties of oligopthiophene-based hybrid gold–graphene junctions were measured with the STM- I ( s ) method to determine attenuation factor and effect specific anchoring groups. It shows that graphene is an effective contact in forming nano-junctions.

In this paper, we develop viscoacoustic asymptotic waveform inversion to estimate velocity and attenuation factor of a medium. Then, we present an application to laboratory ultrasonic data. Viscoacoustic asymptotic waveform inversion is performed using an optimization approach based on the iterative minimization of the mismatch between the seismic data and the computed response. To obtain a fas...

A general purpose Gamma Box Counter is a large scale, high-resolution segmented gamma-ray nondestructive assay system for the assay of nuclear waste containers covering a wide range of composition, mass, and geometry. In order to accurately quantify the activity of the radionuclides in a waste container, a correction for the gamma-ray self-attenuation in the waste matrix must be estimated and a...

The blast vibration attenuation will change as the tunnel cut hole is blasted to create a new free surface. To guarantee safe construction and optimize design parameters, it crucial understand impact of surface on attenuation. Previous studies have often only qualitatively evaluated effect vibration, failing quantify these impacts In this paper, by analyzing decay law velocity under different s...

In this study, we evaluate the attenuation of the dose due to barium-impregnation in the region between the surface of an electronic brachytherapy (EBT) balloon applicator for accelerated partial breast irradiation (APBI) and the prescription point at 1 cm depth in tissue. To perform the study, depth dose curves were calculated using a general purpose multi-particle transport code (FLUKA) for a...

Accurate prediction of rain attenuation is critical for the design terrestrial line-of-sight link systems above 5 GHz, particularly millimetre-wave frequency. Anomalous behaviour in adjustment factor existing models significantly greater than 1 at short distances and has been reported. To solve this problem improve accuracy, a model links proposed. The total described accounts contributions wet...

Obstacles arranged into a pre-fractal shape (Sierpinski carpet) were tested for their blast attenuation abilities using 250 g PE4 at three different scaled distances ( Z = 1.87, 2.24, 2.99 m/kg 1/3 ). Three iterations tested, as well free-field tests comparative purposes. Reductions in peak overpressure up to 26% and specific impulse 19% observed, attributed mechanism known ‘trapping’. This is ...

Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany Despite promising advances, attenuation correction of PET data remains challenging in PET/MRI. Known approaches to estimating attenuation maps from PET emission data take into account only true coincidences and fail to completely determine the attenuation map...

BACKGROUND Dogs with congenital portosystemic shunts (CPSS) have hypoplasia of the intrahepatic portal veins. Surgical CPSS attenuation results in the development of the intrahepatic portal vasculature, the precise mechanism for which is unknown, although new vessel formation by angiogenesis is suspected. HYPOTHESIS That the degree of portal vascular development and the increase in portal vas...