A non-invasive, low-powered, and portable electromagnetic (EM) head imaging system is presented using metamaterial (MTM) loaded compact directional 3D antenna. The antenna consists of two slotted dipole elements with 2×3 3×3 finite MTM array in top ground, respectively, folded parasitic that operate within the frequency range 1.12 GHz to 2.5 GHz. are optimized enhance overall performance regard...

Attenuation correction is very important for quantitative SPECT imaging. We designed an uncollimated non-uniform line array source (non-uniform LAS) for attenuation correction based on transmission computed tomography (TCT) using Tc-99m and compared its performance with an uncollimated uniform line array source (uniform LAS) in a thorax phantom study. This non-uniform LAS was attached to one ca...

The interaction of a helical antenna, mounted on a mobile handset, with a human head phantom is investigated in this paper. Using the Genetic Algorithms (GA) technique combined with the Method of Moments (MoM), an optimization of the antenna structure is achieved regarding the input impedance at the operating frequency. The Finite Difference Time Domain (FDTD) method is then applied to simulate...

For head computed tomography (CT), non-helical scanning has been recommended even in the widely used multi-slice CT (MSCT). Also, an acute stroke imaging standardization group has recommended the non-helical mode in Japan. However, no detailed comparison has been reported for current MSCT with more than 16 slices. In this study, we compared the non-helical and helical modes for head CT, focusin...

Annually, many people are irradiated for diagnostic and therapeutic purposes. Assessment of radiation dose and its related risks to patients are important issues in radiation protection dosimetry. The complex mathematical calculations of the absorbed and effective doses are now done with computers. The calculations are performed with the help of anthropomorphic computational models of human bod...

PURPOSE To introduce the concept of energy minimization-based inverse optimization for external beam radiotherapy. MATERIALS AND METHODS Mathematical formulation of energy minimization-based inverse optimization is presented. This mathematical representation is compared to the most commonly used dose-volume based formulation used in inverse optimization. A simple example on digitally created ...

A special acrylic phantom designed for both magnetic resonance imaging (MRI) and computed tomography (CT) was used to assess the geometric accuracy of MRI-based stereotactic localization with the Leksell stereotactic head frame and localizer system. The acrylic phantom was constructed in the shape of a cube, 164 mm in each dimension, with three perpendicular arrays of solid acrylic rods, 5 mm i...

*Corresponding author: Dr. Tayyeb Allahverdi Pourfallah, Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran. Fax: +98 21 88973653 E-mail: [email protected] Background: Polymer gel dosimetry is still the only dosimetry method for direct measuring of threedimensional dose distributions. MRI Polymer gel dosimeters are tissue equi...

In the past the operational quantity H(p)(3) has been defined for calibration purposes in a slab phantom. Recently, an additional phantom in the form of a cylinder was suggested for eye lens dosimetry as a cylinder much better approximates the shape of a head than a slab. Therefore, this work investigates whether the quantity H(p)(3), when defined in the respective calibration phantom, adequate...

Spatial reproduction in a conventional stereophonic audio system (e.g., stereo or 5.1 surround) works in a small area known as the ”sweet spot“. If the listener changes his position, the phantom source moves in the same direction and finally collapses into the nearer loudspeaker. A play-back system that adjusts the loudspeaker signals depending only on the listener’s position in real-time was e...