We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region at present time t = 0 across the barrier w = −1 into the phantom region in the late universe. The phantom barrier is accordingly not a sharp mathematical divi...

The present paper describes the results of experimentation, carried out on intra-lipid phantom to study the optical clearing properties of glucose. For this intra lipid phantom with different concentration of dextrose levels have been used and the measurement based on selected mathematical parameters have been obtained using indigenously designed amplitude modulated ultrasound & infrared system...

Introduction: Geometric distortion, an important parameter in neurology and oncology. The current study aimed to design and construct a new three-dimensional (3D) phantom using a 3D printer in order to measure geometric distortion and its 3D reproducibility. Material and Methods: In this study, a new phantom ...

We review various folding problems arising in the physics of membranes and polymers. These are (1) the phantom folding of tethered membranes, i.e. the two-dimensional lattice folding; (2) the phantom folding of fluid membranes, i.e. the folding of tessellations of arbitrary genus; (3) the self-avoiding folding of polymers, i.e. the meander problem. All three problems are found to be related to ...

Introduction: In radiation therapy with high-energy photon beams (E > 7 MeV) neutrons are generated mainly in LINACs head thorough (γ, n) interactions. These neutrons affect the shielding requirements in radiation therapy rooms. According to the protocol TG-34, photon absorbed dose of 10Gy can cause permanent damage to the pacemaker and the dose of 2Gy can make minor changes in...

introduction polymer gel dosimeters offer a practical solution to 3d dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. in this study, egsnrc calculated and pagat polymer gel dosimeter measured dose profiles from single shot irradiation with 18 mm collimator of gamma knife in homogeneous and inhomogeneous phantoms were compared with eac...

In this paper, we present a novel implementation of a dose calculation application, based on the GEANT4 Monte Carlo toolkit. Validation studies were performed with an homogeneous water phantom and an Alderson-Rando anthropomorphic phantom both irradiated with high-energy photon beams produced by a clinical linear accelerator. As input, this tool requires computer tomography images for automatic...

In computed tomography, analytical fan-beam (FB) and cone-beam (CB) image reconstruction often involves a view-dependent data differentiation. The implementation of this differentiation step is critical in terms of resolution and image quality. In this work, we present a new differentiation scheme that is robust to changes in the data acquisition geometry and to coarse view sampling. Our scheme...

Purpose: Patients treated with intensity-modulated radiation therapy (IMRT) for head-and-neck cancer are often positioned supine on a carbon fibre board to which a thermoplastic mask is attached to immobilise the head and shoulders. For patients unable to tolerate a supine position, we developed a tilting board that accommodates a full-scale head-and-shoulder mask. Materials and methods: Phanto...

INTRODUCTION The calibration of whole-body counter (WBC), that means the determination of the body burden of radionuclides, is generally carried out by comparing the measurements between the human body and the standard calibration phantom. The measured counting efficiency is affected by the deference of size, shape and distribution of radioactivity between them. Therefore, if the standard phant...